Salmonella typhimurium

J Bacteriol, 1989 Apr, 171(4), 2049 - 55
An alkyl hydroperoxide reductase induced by oxidative stress in Salmonella typhimurium and Escherichia coli: genetic characterization and cloning of ahp; Storz G et al.; The ahp genes encoding the two proteins (F52a and C22) that make up an alkyl hydroperoxide reductase were mapped and cloned from Salmonella typhimurium and Escherichia coli . Two classes of oxidant-resistant ahp mutants which overexpress the two proteins were isolated . ahp-1 was isolated in a wild-type background and is dependent on oxyR, a positive regulator of defenses against oxidative stress . ahp-2 was isolated in an oxyR deletion background and is oxyR independent . Transposons linked to ahp-1 and ahp-2 or inserted in ahp mapped the genes to 13 min on the S . typhimurium chromosome, 59% linked to ent . Deletions of ahp obtained in both S . typhimurium and E . coli resulted in hypersensitivity to killing by cumene hydroperoxide (an alkyl hydroperoxide) and elimination of the proteins F52a and C22 from two-dimensional gels and immunoblots . ahp clones isolated from both S . typhimurium and E . coli complemented the cumene hydroperoxide sensitivity of the ahp deletion strains and restored expression of the F52a and C22 proteins . A cis-acting element required for oxyR-dependent, rpoH-independent heat shock induction of the F52a protein was present at the S . typhimurium but not the E . coli ahp locus.

Carcinogenesis, 1989 Apr, 10(4), 733 - 6
Mutagenicity and carcinogenicity of smoked meat from Nagaland, a region of India prone to a high incidence of nasopharyngeal cancer; Sarkar S et al.; The incidence of nasopharyngeal cancer (NPC) in the northeastern part of India is reported to be high . A possible correlation between consumption of smoked meat by the tribal people and high suceptibility to NPC has been postulated . The charred portion of smoked beef and meat of other animals was collected from this area, extracted with acetone and the extract (SME) was tested using the Ames test as well as for chromosomal aberration in mouse bone marrow cells and carcinogenicity using Swiss bare mice . It was observed that SME was mutagenic in all five strains of Salmonella typhimurium (TA98, TA1538, TA100, TA1535 and TA1537), with or without S9 mix, and was clastogenic in a mammalian test system . SME also has the potential to induce skin papilloma as well as systemic tumours in Swiss bare mice . Chemical analysis of SME revealed the presence of low concentrations of volatile nitrosamines.

Arch Biochem Biophys, 1989 Apr, 270(1), 77 - 83
Effect of spermidine on the development of bacteriophage SP6; Verma M; Bacteriophage SP6 is a virulent phage of Salmonella typhimurium which behaves differently than other phages of the same host . The effect of spermidine on SP6 infection of S . typhimurium has been found to depend on the time of addition of spermidine with respect to the time of addition of the phage and also on the composition of the growth medium . If spermidine was added prior to or within a short time after infection, the cells survived . Under this condition the invading DNA appeared to remain trapped in the cell membrane, and there was no expression of the phage genome . If spermidine was added after the initiation of the infection process, the replication of the phage was inhibited but the cells did not survive . Furthermore, if spermidine was added after DNA synthesis was over, there was no effect of spermidine on phage multiplication . Spermidine was found to affect phage DNA synthesis but not host DNA synthesis.

Cancer Res, 1989 Apr 1, 49(7), 1778 - 82
Influence of the alkyl substituent on mutagenicity and covalent DNA binding of bay region diol-epoxides of 7-methyl- and 7-ethylbenz(a)anthracene in Salmonella and V79 Chinese hamster cells; Glatt H et al.; The anti-isomers of the bay region diol-epoxides of the strong carcinogen 7-methylbenz(a)anthracene and of the weak carcinogen 7-ethylbenz(a)anthracene were investigated for mutagenicity in Salmonella typhimurium (reversion of the his - strains TA98 and TA100 to prototrophy) and V79 Chinese hamster cells (acquisition of resistance to 6-thioguanine and ouabain; formation of micronuclei) . In addition, in the V79 cells, the levels of the DNA adducts formed were determined by 32P-postlabeling analysis . In terms of mutations per nmol compound administered, the methyl derivative was four to 10 times more potent, depending on the genetic endpoint, than its ethyl congener . However, when the results were expressed as mutations per adduct, the difference between the two diol-epoxides was small . Therefore, a higher level of DNA modification appears to be the major reason for the stronger mutagenicity of the methyl derivative . However, both diol-epoxides had similar half-lives (about 9 min) in physiological buffer, as determined from the decline in mutagenic activity after preincubation of the test compound . These results suggest that the effect of the 7-alkyl group on the extent of reaction with DNA is more a result of steric factors than of a change in the intrinsic chemical reactivity of the diol-epoxides.

J Gen Microbiol, 1989 Apr, 135 ( Pt 4), 1017 - 25
Chemical and biological properties of lipopolysaccharide, lipid A and degraded polysaccharide from Wolinella recta ATCC 33238; Kumada H et al.; Lipopolysaccharide (LPS) was isolated and purified from Wolinella recta ATCC 33238 by the phenol-water procedure and RNAase treatment . The sugar components of the LPS were rhamnose, mannose, glucose, heptose, 2-keto-3-deoxyoctonate (KDO) (3-deoxy-D-manno-octulosonate) and glucosamine . The degraded polysaccharide prepared from LPS by mild acid hydrolysis was fractionated by Sephadex G-50 gel chromatography into three fractions: (1) a high-molecular-mass fraction, eluting just behind the void volume, consisting of a long chain of rhamnose (22 mols per 3 mols of heptose residue) with attached core oligosaccharide; (2) a core oligosaccharide containing heptose, glucose and KDO, substituted with a short side chain of rhamnose; (3) a low-molecular-mass fraction containing KDO and phosphate . The main fatty acids of the lipid A were C12:0, C14:0, 3-OH-C14:0 and 3-OH-C16:0 . The biological activities of the LPS were similar to those of Salmonella typhimurium LPS in activation of the clotting enzyme of Limulus amoebocytes, the Schwartzman reaction and mitogenicity for murine lymphocytes, although all the biological activities of lipid A were lower than those of intact LPS.

Genetics, 1989 Apr, 121(4), 635 - 49
The isolation and sequence of missense and nonsense mutations in the cloned bacteriophage P22 tailspike protein gene; Schwarz JJ et al.; Twenty-seven new mutations in the structural gene for the Salmonella typhimurium bacteriophage P22 tailspike protein have been isolated, mapped using a powerful plasmid-based genetic system and their DNA sequence changes determined . The mutations were generated by hydroxylamine treatment of the cloned gene on a plasmid expression vector . Assaying the activity of the tailspike protein produced from this plasmid and screening for plasmid mutants were accomplished by the in situ complementation of P22 capsids imbedded in soft agar to produce infectious phage . Deletion mutations in the cloned gene have been constructed by a two step procedure involving oligonucleotide linker insertion and in vitro deletion by restriction endonuclease digestion . The deletions, whose physical endpoints were determined by DNA sequencing, define 12 genetic and physical intervals into which the new mutations were mapped by marker rescue experiments . These deletions were transferred to phage P22 by recombination and used to map mutations carried on plasmids . Following mapping, the nucleotide change for each of the mutations was determined by DNA sequencing . The majority were absolute missense mutations although both amber and ochre nonsense mutations were also identified in the protein coding portion of the gene . The suppression pattern of the nonsense mutations was determined on several nonsense suppressors . Four of the mutations cause severely depressed levels of tailspike protein expression from both the cloned gene on the plasmid expression vector and from P22 phage carrying these mutations . These mutations were identified as nucleotide changes in what is probably the P22 late operon transcription terminator which immediately follows the tailspike protein coding sequence.

FEMS Microbiol Immunol, 1989 Apr, 1(5), 279 - 84
Susceptibility of Salmonella typhimurium and Salmonella typhi to oxygen metabolites; Ishibashi Y et al.; The susceptibility of Salmonella typhimurium LT2 and S . typhi 1079 to oxygen metabolites were compared . S . typhimurium LT2 and S . typhi 1079 were killed to an equal extent (about 40%) by the xanthine-xanthine oxidase (200 mU/ml) system . Among the various scavengers of oxygen metabolites, catalase alone inhibited the killing of S . typhimurium LT2 and S . typhi 1079 by the xanthine-xanthine oxidase system, indicating that hydrogen peroxide contributed to the killing of Salmonellae . The respiratory burst of murine macrophages was efficiently triggered by the ingestion of S . typhimurium LT2, S . typhimurium SL1102, and S . typhi 1079 and all to the same extent . However, in the range of the concentration of hydrogen peroxide produced by murine macrophages, neither S . typhimurium LT2 nor S . typhi 1079 were killed . Only S . typhimurium SL1102, a rough mutant of S . typhimurium LT2, was markedly susceptible under these conditions . The findings suggest that both S . typhimurium LT2 and S . typhi 1079 are resistant to oxygen-dependent killing mechanisms.

Mol Gen Genet, 1989 Apr, 216(2-3), 517 - 25
The PEP: fructose phosphotransferase system in Salmonella typhimurium: FPr combines enzyme IIIFru and pseudo-HPr activities; Geerse RH et al.; We have cloned the fru operon of Salmonella typhimurium, coding for the enzymes of the phosphoenolpyruvate: fructose phosphotransferase system (Fructose PTS) . The fruFKA operon consists of three genes: fruF coding for FPr, fruK for fructose 1-phosphate kinase and fruA for Enzyme IIFru . Insertions of Tn5 in the different genes were isolated and the activities of the gene products were measured . Expression of the plasmid-encoded fru operon in the maxicell system resulted in the synthesis of three proteins with molecular weights of 47 kDa (fruA), 39 kDa (fruF) and 32 kDa (fruK) . We have sequenced the fruF gene and the regulatory region of the fru operon . In contrast to previously published results, we have found that the fruF gene codes for a 39 kDa protein, FPr, that combines Enzyme IIIFru and pseudo-HPr activities . The N-terminal part of FPr is homologous to the cytoplasmic domain of the Escherichia coli Enzyme IIMtl, as well as several Enzymes IIIMtl from gram-positive bacteria . The C-terminal domain shows homology to HPr of E . coli and several gram-positive organisms . The fru operon is regulated by a repressor, FruR . We have constructed an operon fusion between fru and the galK gene and shown that regulation of the fru operon by FruR takes place at the level of transcription.

Mol Gen Genet, 1989 Apr, 216(2-3), 210 - 6
Absence of insertions among spontaneous mutants of Salmonella typhimurium; Casadesus J et al.; While insertion sequences (IS) in Escherichia coli transpose frequently to generate spontaneous insertion mutants, such mutations are rare in Salmonella typhimurium: the only documented insertion mutation is a hisD mutation caused by the Salmonella-specific IS element IS200 . To obtain more examples of IS200 insertion mutations and to seek additional types of IS elements in Salmonella, we selected and characterized 422 independent, spontaneous His- mutants and some 2100 additional mutants that are not necessarily independent . None of the mutants showed the absolute polar effect characteristic of insertion mutations or the reversion properties characteristic of insertions (low spontaneous reversion frequency and no reversion induction by chemical mutagens) . A few mutants, showing a high spontaneous reversion frequency, were screened physically . No insertion mutations were found . Thus insertion mutations appear to be rare in S . typhimurium, in strong contrast to E . coli and despite the possession in Salmonella of at least one type of insertion element (IS200) . These results suggest that in Salmonella transposition of the endogenous elements has been controlled . The transposition ability of the elements may have been reduced or favored target sites removed from the host genome.

Mol Gen Genet, 1989 Apr, 216(2-3), 204 - 9
Transcriptional occlusion of transposon targets; Casadesus J et al.; In Salmonella typhimurium, insertion of transposons Tn5, Tn10 and bacteriophage Mu is inhibited by transcription of some target sequences . The transcription effects on Tn5 are large when the lac operon is a target but are limited to a slight effect on the hisG gene of the his operon . The Tn10 element shows target occlusion in both operons . Phage Mu has been shown previously to be inhibited for insertion into the lac operon . In the his operon Mu is only inhibited for insertion into the hisG gene . The variability of the inhibition effect from one sequence to another suggests site or regional specificity for transcription effects . Reducing the probability of insertion into transcribed sequences may be of selective importance to transposons since it reduces the risk of killing the host while maintaining the ability to transpose.

Mutat Res, 1989 Apr, 211(2), 291 - 9
Modulation of mutagenesis involving precise excision of transposon Tn10; Hafner LM et al.; Precise excision of transposon Tn10 results in reversion of the Trp- phenotype to Trp+ in a trp-1014::Tn10 strain of Salmonella typhimurium, and also occurs at a markedly higher frequency in a strain carrying the temperature-sensitive polA7 allele . The frequency with which precise excision events occurs can be modified by the plating medium, results indicating that the great majority of mutants which arise on broth-supplemented or tryptophan-supplemented minimal media actually arise on the selective plating medium . Trp+ revertants (1000) arising from excision of Tn10 were purified by re-streaking for single colonies; none were found to retain the Tn10 encoded resistance to tetracycline . Yields of Trp+ revertants of the polA7 strain were consistently higher when glycerol rather than glucose was used as sole carbon source in the selective medium . Clean excision of Tn10 can also be increased by ultraviolet irradiation in (R) plasmid-free strains, and is further increased in strains carrying an N-group plasmid (R205, R46 or pKM101) . Ultraviolet-induced precise excision of Tn10 also occurs at a much enhanced frequency in a strain with a deletion through the uvrB gene; in this case, however, the addition of plasmid pKM101 leads to a decrease in yields of ultraviolet-induced precise excision events.

Zhongguo Yi Xue Ke Xue Yuan Xue Bao, 1989 Apr, 11(2), 97 - 101
{Preliminary study on mutagenicity of MeIQ and extracts of fried fish and antimutagenicity of some dietary factors}; Liu XL; 2-amino-3,4-dimethylimidazo (4,5-f) quinoline (MeIQ) and extracts of fried fish showed a strong mutagenicity as reflected backward mutation in Salmonella typhimurium . Significant inhibitory effects on mutagenicity induced by MeIQ or extracts of fried fish were found by simultaneous treatment with extracts of fresh vegetables, fruits and especially green tea antioxidants . The results indicated that some mutagens and/or carcinogens might be produced during high temperature cooking of some animal meats . The frequent intake of fresh vegetables, fruits and green tea might be beneficial in the prevention of human cancer.

Biochimie, 1989 Apr, 71(4), 477 - 89
L-Histidinol phosphate aminotransferase from Salmonella typhimurium . Kinetic behavior and sequence at the pyridoxal-P binding site; Hsu LC et al.; A coupled assay with alpha-hydroxyglutarate dehydrogenase was used to analyze the kinetic behavior of histidinol phosphate aminotransferase from Salmonella typhymurium . Data obtained from studies of initial velocity, inhibition by products or substrate analogues, isotope exchange rates, and the determination of the equilibrium constant were consistent only with a Ping-Pong Bi Bi mechanism . Variations in inhibition patterns by different substrate analogues indicate that the microenvironment about the pyridoxal phosphate and the pyridoxamine phosphate forms of histidinol phosphate amino-transferase are different, and favor the presence of one active site with partially overlapping substrate-binding subsites for these 2 forms of the enzyme . Histidinol phosphate aminotransferase also catalyzes decomposition of beta-chloro-L-alanine to pyruvate, NH3 and Cl-; no transamination of this substrate occurs and inactivation of the enzyme accompanies this reaction . After reduction of histidinol-P aminotransferase with {3H}NaBH4, carboxymethylation, and tryptic digestion, one major radioactive peptide absorbing at 325 nm was isolated . Its primary structure was determined to be TLSK*AFALAGLR, where K* is the P-pyridoxyllysine residue . Although this peptide is only 30-40% homologous with the corresponding segment reported for other transaminases, all of these peptides are similar in placement of an hydroxyamino acid residue three residues upstream from the lysine residue, and in the cluster of hydrophobic amino acid residues immediately following the lysine residue.

Appl Environ Microbiol, 1989 Apr, 55(4), 832 - 6
Cell surface charge characteristics and their relationship to bacterial attachment to meat surfaces; Dickson JS et al.; Cell surface charge and hydrophobicity of Bacillus subtilis, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium, Serratia marcescens, Staphylococcus aureus, and Staphylococcus epidermidis were determined by hydrocarbon adherence, hydrophobic interaction, and electrostatic interaction chromatography . Surface charge and hydrophobicity were compared with the initial attachment values and rates of attachment of the bacteria to meat surfaces . There was a linear correlation between the relative negative charge on the bacterial cell surface and initial attachment to lean beef muscle (r2 = 0.885) and fat tissue (r2 = 0.777) . Hydrophobicity correlated well with attachment to fat tissue only . The relative hydrophobicity of each bacterium was dependent on the specific method of determination, with wide variations noted between methods.

Mutat Res, 1989 Apr, 222(4), 403 - 7
Modifying role of dietary factors on the mutagenicity of aflatoxin B1: in vitro effect of sulphur-containing amino acids; Shetty TK et al.; Sulphur-containing amino acids including some derivatives have been tested for their effectiveness in suppressing the mutagenic activity of aflatoxin B1 in Salmonella typhimurium strains provided with a rat liver activation system . Cysteine and N-acetylcysteine have been found to be most effective in the 2 strains tested (TA100 and TA98) . Glutathione (oxidised and reduced forms) has shown partial activity, while cystine and methionine are found to be partially effective only in strain TA100 . Inhibition of mutagenicity may be due to interaction of these substances with microsomal enzymes resulting in interference with the formation of ultimate mutagenic species.

Mutat Res, 1989 Apr, 222(4), 393 - 401
Modifying role of dietary factors on the mutagenicity of aflatoxin B1: in vitro effect of plant flavonoids; Francis AR et al.; Eighteen flavonoids have been tested for their ability to inhibit the mutagenicity of aflatoxin B1 (AFB1) towards strains TA100 and TA98 of Salmonella typhimurium provided with a rat liver activation system . These flavonoids belong to 5 different groups: flavone, isoflavone, flavanone, flavanol and flavonol, and many individual members are natural products present in edible portions of a variety of food plants . Several flavonoids exhibited significant inhibitory ability in both strains . Flavonols in general are more active in this regard, while flavanones show a strain-specific response . The flavanol group of compounds did not display any activity . Among the most effective flavonoids are kaempferol, morin, fisetin, biochanin A and the glycoside rutin, all of which exhibit a dose-dependent inhibition pattern . Kaempferol and rutin, in particular, show exceptional activity inasmuch as, on a molar basis, only a 10-fold excess dose of each can inhibit the mutagenic activity of AFB1 in strain TA98 by 50% . The action of flavonoids is possibly mediated through interaction with microsomal activating enzymes . Previous evidence from this laboratory about their inhibitory action on DNA-adduct formation and metabolic activation together with the present results suggests that certain flavonoids, notably polyhydroxylated flavonols, may have potential anticarcinogenic activity against AFB1.

Mutat Res, 1989 Apr, 222(4), 343 - 50
Dimethylglycine and chemically related amines tested for mutagenicity under potential nitrosation conditions; Hoorn AJ; Dimethylglycine (DMG) and the chemically related amino acids glycine, sarcosine (monomethylglycine) and betaine (trimethylglycine) were tested in Salmonella typhimurium strain TA100 after treatment with sodium nitrite under acidic conditions using a modified Ames Salmonella/microsome assay as reported by Colman et al . (1980) . The increase in the number of revertants observed both with and without metabolic activation was also induced in the control mixtures without adding the amines . From the subsequent testing of the individual components of the mixtures, we concluded that non-consumed nitrite was responsible for the mutagenic responses observed in the different reaction mixtures, and not the amines themselves . There were no consistent indications of mutagenic activity of the DMG test mixture as compared to the control mixture which exhibited both consistent mutagenic activity and a toxic effect which was not increased by the addition of DMG . In fact, DMG seemed to decrease the toxicity of the control reaction solution to the Salmonella which was clearly observed at the higher doses . DMG cannot be considered mutagenic under the test conditions employed . The same can be said of the other amino acids as well.

J Biol Chem, 1989 Mar 25, 264(9), 5006 - 14
Reconstitution of the histidine periplasmic transport system in membrane vesicles . Energy coupling and interaction between the binding protein and the membrane complex; Prossnitz E et al.; The periplasmic histidine transport system of Salmonella typhimurium has been reconstituted in isolated right-side-out membrane vesicles . The reconstituted system is entirely dependent on both the periplasmic protein, HisJ, and the membrane-bound complex, composed of proteins HisQ, HisM, and HisP . Transport is also dependent on the presence of ascorbate and phenazine methosulfate, which provide the energy for transport . Ascorbate oxidation generates a proton-motive-force, which allows ATP synthesis . ATP (or a cogenerated molecule) appears to be the immediate energy donor . Dissipation of the proton-motive-force or reduction of the level of ATP by a variety of treatments results in inhibition of transport . Vanadate inhibits transport, indicating that ATP utilization is necessary to energize transport . The interaction between liganded HisJ and the membrane complex has been measured directly: it displays Michaelis-Menten type kinetics, with a K1/2 of approximately 65 microM . The significance of this finding in terms of transport properties of whole cells is discussed.

J Biol Chem, 1989 Mar 5, 264(7), 3998 - 4002
Reconstitution of periplasmic transport in inside-out membrane vesicles . Energization by ATP; Ames GF et al.; The periplasmic histidine permease of Salmonella typhimurium has been reconstituted in inside-out vesicles (IOV) of Escherichia coli by disrupting the cells with a French press in the presence of a high concentration of the periplasmic histidine-binding protein, HisJ . Efflux from IOV, which is equivalent to uptake in whole cells, is induced by ATP . The reconstituted system depends on the presence of the membrane-bound permease proteins, HisQ, HisM, and HisP, and does not function if reconstitution is performed in the presence of a mutant HisJ protein, HisJ5625, that can bind histidine normally but can't interact properly with the membrane complex . Efflux is not induced by the nonhydrolyzable ATP analog, adenyl-5'-yl imidodiphosphate, supporting the contention that ATP hydrolysis is necessary . 8-Azido ATP inactivates IOV, indicating that the ATP effect occurs through the HisP protein, which has previously been shown to be modified by 8-azido ATP (Hobson, A., Weatherwax, R., and Ames, G.F.-L . (1984) Proc . Natl . Acad . Sci . U . S . A . 81, 733-7337) . The estimated Km of the vesicles for ATP is about 200 microM . Vanadate, an inhibitor of phosphohydrolase enzymes, inhibits ATP-induced efflux . We conclude that ATP is likely to be the proximal energy source for periplasmic permeases.

J Biol Chem, 1989 Mar 5, 264(7), 3794 - 8
In vitro use of monoclonal antibodies in Escherichia coli S-30 extracts to determine the RNA polymerase sigma subunit required by a promoter; Jovanovich SB et al.; RNA polymerase requires one of a family of sigma subunits for specific promoter recognition and initiation . We have developed an in vitro method to define the RNA polymerase sigma subunit required by a promoter . Mouse monoclonal antibodies specific for either Escherichia coli sigma 70 or sigma 32 or Salmonella typhimurium sigma 54 were added to an E . coli coupled transcription-translation S-30 extract programed with a DNA template containing the promoter of interest . Using the representative lacUV5, glnAP2, and rpoDHS promoters as controls, we found that monoclonal antibodies to a given sigma subunit strongly inhibited transcription from cognate promoters which utilized that sigma subunit, but had little effect on transcription from noncognate promoters which used other sigma subunits . Supplementation of the S-30 extract with purified sigma 70, sigma 54, or RNA polymerase sigma 32-holoenzyme stimulated expression from the cognate promoters and inhibited noncognate promoters . These two tests, addition of monoclonal antibodies and addition of sigma subunits, provide a rapid means of identifying whether the sigma subunit required by any promoter expressed in the S-30 extract is sigma 70, sigma 54, or sigma 32 . We suggest that this method may provide a systematic approach for identifying promoters which use as yet uncharacterized sigma subunits.

Carcinogenesis, 1989 Mar, 10(3), 483 - 7
The mouse-skin carcinogenicity of a mutagenic fraction from beech wood dusts; Mohtashamipur E et al.; A life-time mouse-skin carcinogenicity assay was conducted using female NMRI mice to evaluate the possible direct carcinogenic activity of a mutagenic fraction isolated from beech wood dusts . The samples of untreated beech wood dusts were extracted with methanol at pH3 and were purified from the inhibitory compounds toxic to bacteria, using silica-gel column chromatography . The fraction obtained after passing through the column was tested for mutagenicity in the Ames assay employing Salmonella typhimurium TA100 in the presence of Aroclor-treated rat-liver-S9 . Using acetone as the vehicle, this mutagenic fraction was tested for carcinogenicity on an area of 1-1.5 cm shaved skin of mice on the lower back . The mice were treated with half of each dose, twice a week, for only 3 months . The total doses applied per week were 2.5, 5, 7.5 or 10 g equivalent dust/mouse . No substance was used as promoter . No statistically significant difference was found when the life spans of treated and untreated animals were compared . The observed carcinogenic effect was based on tumours and lesions found only on the site of application of the test material . Of 210 mice (effective number, 129) serving as the negative controls, three developed skin lesions but no tumours . Of 280 treated animals (effective number, 188) 34 developed different types of tumours and 20 had a uniform type of precancerous skin lesion . Of 34 tumours observed 21 were originated from the skin, 12 from the mammary glands beneath the site of application, and one was a lymphoma . Comparing the negative controls with the treated animals, the overall carcinogenic effect observed was dose-dependent and statistically significant . Excluding the mammary tumours and a lymphoma found beneath the site of treatment, the overall induction of skin tumours was still significant . However, the dose-dependent increase in the number of skin tumours alone was not statistically significant . These results suggest that beech wood dust contains mutagenic and carcinogenic constituent(s).

Carcinogenesis, 1989 Mar, 10(3), 461 - 9
Comparison of the in vitro metabolisms and mutagenicities of dibenzo{a,c}anthracene, dibenzo{a,h}anthracene and dibenzo{a,j}anthracene: influence of norharman; Lecoq S et al.; The comparison of the behaviour of three dibenzoanthracene (DBA) isomers, dibenzo{a,c}anthracene (DB{a,c}A), dibenzo{a,h}anthracene (DB{a,h}A) and dibenzo{a,j}anthracene (DB{a,j}A), polycyclic aromatic hydrocarbons (PAHs), whose carcinogenicity varies from very potent to apparently inactive, has been carried out . Influence of norharman (NH; 9H-pyrido{3,4-b}indol) was investigated for mutagenicity (reversion of histidine prototrophy) on Salmonella typhimurium TA 100, using 3-methylcholanthrene (3-MC)-induced rat liver microsomes or S9 (post-mitochondrial fractions) . A correlation with its influence, on the in vitro metabolism of radiolabelled molecules by the same enzymatic systems, was carried out . NH enhances the mutagenicities of DB{a,c}A and DB{a,h}A which are very well known mutagenic and carcinogenic PAHs . Contrary to its two isomers, the mutagenic potency of DB{a,j}A, which is considered as a weak mutagen and not a carcinogen, is strongly inhibited by NH . The balance sheets of the in vitro metabolism by microsomal enzymes, where the conjugation is excluded, were reported with or without NH . In the presence of the latter, the amounts of remaining DBAs slightly decreased while the metabolites covalently bound to microsomal proteins strongly decreased and the amount of hydrophobic metabolites highly increased . At the same time, the HPLC elution profiles of the metabolism pathways of the three DBAs are found to be modified in a similar way by NH: some of the metabolites are highly enhanced, and for all three DBAs, a tetraol, not detectable in the absence of NH, emerges . The results are discussed with regard to possible effects of NH.

Mutat Res, 1989 Mar, 222(3), 223 - 35
DNA adduct formation, metabolism, and morphological transforming activity of aceanthrylene in C3H10T1/2CL8 cells; Nesnow S et al.; Aceanthrylene (ACE), a cyclopenta-fused polycyclic aromatic hydrocarbon (CP-PAH) related to anthracene, has been studied for its ability to be metabolized, to form DNA adducts, and to morphologically transform C3H10T1/2CL8 mouse embryo fibroblasts in culture . Although ACE has been previously shown to be a strong mutagen in Salmonella typhimurium strains TA89 and TA100, it did not transform C3H10T1/2 cells (0.4-16 micrograms/ml) under 2 treatment protocols: treatment (for 24 h) 1 day after seeding the cells; treatment (for 24 h) 5 days after seeding the cells . Both protocols are effective in detecting the morphological transforming activity of PAH and CP-PAH and the latter protocol has been shown to be effective in detecting chemicals which are active in the first protocol only with the additional treatment of the cells with a tumor promoter . ACE is metabolized by C3H10T1/2 cells to ACE-1,2-dihydrodiol (the cyclopenta-ring dihydrodiol) at a rate of 450 pmoles ACE-1,2-dihydrodiol formed/h/10(6) cells . ACE-7,8-dihydrodiol and ACE-9,10-dihydrodiol, identified as major Aroclor-1254-induced rat liver microsomal metabolites from their UV, NMR, and mass spectral data, were not identified in incubations of C3H10T1/2 cells with ACE . ACE-DNA adducts in C3H10T1/2 cells were isolated, separated, identified, and quantitated using the 32P-postlabeling method . ACE forms 4 major adducts and each was identified as an ACE-1,2-oxide/2'-deoxyguanosine adduct . The level of adduction was 2.18 pmoles ACE adducts/mg DNA after a 24-h incubation of ACE (16 micrograms/ml) with C3H10T1/2 cells . ACE-DNA adduct persistence and repair were evaluated in C3H10T1/2 cells using a hydroxyurea block after ACE treatment . ACE-DNA adducts were not repaired under the conditions used in the morphological transformation studies . Thus, ACE provides an interesting example of a mutagenic PAH which is metabolized by C3H10T1/2 cells to active intermediates, forms relatively stable and persistent 2'-deoxyguanosine adducts in C3H10T1/2 cells, and yet induces no detectable morphological transforming activity under the experimental conditions used.

Mutat Res, 1989 Mar, 222(3), 155 - 60
The release of mutagens from airborne particles in the presence of physiological fluids; van Houdt JJ et al.; Airborne particulates collected indoors in residences and outdoors were extracted by soxhlet extraction and sonication with methanol . In a comparative study in which mutagenic activity was evaluated in the Salmonella typhimurium reversion assay both soxhlet extraction and sonication proved to be suitable extraction methods . First, the residue, obtained by sonication of loaded filters with methanol followed by evaporation to dryness (tar), was sonicated with newborn calf serum and lung lavage fluid from pigs . All serum extracts of the tar were mutagenic to Salmonella typhimurium TA98, and contained direct- and indirect-acting mutagens . However, the mutagenic activity recovered by serum was only about half of the total mutagenic activity of the tar . The other part of the mutagenic activity remained in the tar . Lung lavage fluid was only able to remove 5-10% of direct-acting mutagens from the tar of all samples . About 20% of indirect-acting mutagens from indoor air were recovered in lung lavage fluid, while the lung lavage fluid extract from outdoor air did not show indirect mutagenic activity . Second, mutagenic activity recovered by direct sonication of the filters with physiological fluids was comparable with the recovery obtained by sonication of the tar . However, after sonication of the filter with lung lavage fluid hardly any mutagenic activity remained on the filter, whereas after sonication of the tar a clear mutagenic activity was observed in the non-soluble residue.

Cancer Res, 1989 Mar 1, 49(5), 1187 - 92
Human and rat kidney cell metabolism of 2-acetylaminofluorene and benzo(a)pyrene; Rudo KM et al.; The metabolism and mutagenic activation of the model carcinogens benzo(a)pyrene {B(a)P} and 2-acetylaminofluorene (AAF) by human and rat kidney cells were measured . A slicing technique followed by enzyme digestion was utilized to obtain the kidney cells . Although levels of total metabolism of B(a)P by rat and human kidney cells were similar, analysis of specific metabolites of B(a)P indicated that species differences existed . Human kidney cells produced the organic-soluble metabolites B(a)P-9,10-diol, B(a)P-4,5-diol, B(a)P-7,8-diol, B(a)P-3,6-quinone, and B(a)P-9-phenol . Rat kidney cells produced organic-soluble B(a)P-pre-9,10-diols, B(a)P-9,10-diol, B(a)P-4,5-diol, and B(a)P-6,12-quinone . Both species produced sulfate and glucuronide conjugates of all products . For AAF, kidney cells from some human tissues produced up to four times the level of total metabolites compared to rat kidney cells . Organic-soluble metabolites were qualitatively similar between the species and consisted of 2-aminofluorene (AF), N-hydroxy-AAF and ring-hydroxylated products at the 1, 3, 5/9, 7, and 8 positions . Sulfate and glucuronide conjugates of these metabolites were also detected . Human interindividual variation with kidney cells was about 2.5-fold for total AAF metabolism and up to 6-fold for individual AAF metabolites . For B(a)P metabolism, human interindividual variation in total metabolism was low while for specific metabolites there was up to a 4-fold variation . Levels of AAF and AF cell-mediated Salmonella typhimurium mutagenesis were significantly higher with human cells as compared to rat kidney cells . It appears that the differences between human and rodent kidney cell metabolism of chemical carcinogens vary with the chemical class and understanding these differences will be necessary in the extrapolation of rodent carcinogenesis data to humans.

Indian J Exp Biol, 1989 Mar, 27(3), 207 - 9
Effect of Emblica officinalis Gaertn . (Indian gooseberry) fruit extract on sodium azide and 4-nitro-o-phenylenediamine induced mutagenesis in Salmonella typhimurium; Grover IS et al.; Water, acetone and chloroform extracts of E . officinalis fruit reduced sodium azide and NPD induced his+ revertants significantly in TA100 and TA97 a strains respectively of S . typhimurium . The chloroform extract was less active as compared to water and acetone extracts . Autoclaving of water extract for 15 min did not reduce its activity . The enhanced inhibitory activity of the extracts on pre-incubation suggests the possibility of desmutagens in the extracts . Besides ascorbic acid, a constituent of the extract, the role of other antimutagenic factors in the extract cannot be ruled out.

Biofactors, 1989 Mar, 2(1), 35 - 44
Biochemical and genetic analysis of Salmonella typhimurium and Escherichia coli mutants defective in specific incorporation of selenium into formate dehydrogenase and tRNAs; Stadtman TC et al.; Mutation of a single gene, referred to as selA1 in Salmonella typhimurium and as selD in Escherichia coli, results in the inability of these organisms to insert selenium specifically into the selenopolypeptides of formate dehydrogenase and into the 2-selenouridine residues of tRNAs . The mutation does not involve transport of selenite into the cell or reduction of selenite to selenide since both mutant strains synthesize selenocysteine and selenomethionine from added selenite and incorporate these selenoamino acids non-specifically into numerous proteins of the bacterial cells . Complementation of the mutation in S . typhimurium with the selD gene from E . coli indicates functional identity of the selA1 and selD genes . Although the selA1 gene maps at approximately 21 min on the S . typhimurium chromosome and the selD gene at approximately 38 min on the E . coli chromosome, only a single gene in wild-type S . typhimurium hybridized to the E . coli selD gene probe . Transformation of the mutant Salmonella strain with a plasmid bearing the E . coli selD gene restored formate dehydrogenase activity, 75Se incorporation into formate dehydrogenase seleno-polypeptides and {75Se}seleno-tRNA synthesis . Transformation with an additional plasmid carrying an E . coli formate dehydrogenase selenopolypeptide-lacZ gene fusion showed that the selD gene allowed readthrough of the UGA codon and synthesis of beta-galactosidase in the Salmonella mutant.

Biokhimiia, 1989 Mar, 54(3), 434 - 9
{Effect of lipopolysaccharide toxin on lipid and protein composition of human serum low density lipoproteins}; Viktorov AV et al.; Complexes of lipopolysaccharide (LPS) B of Salmonella typhimurium with human low density lipoproteins (LDL) formed during in vitro coincubation via spontaneous incorporation of LPS (complex LDL-LPS) or through the incorporation stimulated by the serum protein fraction (LPS/LDL complex) were studied . The LPS/LDL complex was shown to maximally bind 0.24 mg of LPS per 1 mg of LDL protein, whereas the LDL-LPS complex contained only 0.07 mg of LPS per 1 mg of LDL protein . The observed incorporation of LPS into LDL particles was not possibly associated with a transfer of lipids or proteins from high density lipoproteins to LDL . The insertion of LPS was probably accompanied by the expulsion of a small portion of phosphatidylcholine molecules from the outer monolayer of LDL into the aqueous medium and by an increase in the phosphatidylethanolamine concentration in LDL . Simultaneously, the level of esterified cholesterol in the LPS/LDL complex decreased, and the concentrations of free cholesterol and triacylglycerols showed a rise . The level of free fatty acids in the LPS/LDL complex increased more than twofold compared with intact LDL . The enhancement of LPS incorporation did not result in the insertion of any serum proteins into LDL, in which apoB-100 remained the major apolipoprotein (ca . 90%); apoB-100 fragments made up to 5-7%, whereas apoE and apoC contained altogether ca . 3-5% . It is suggested that the LPS/LDL complex obtained can bind to three types of cell receptors, i.e., apoB/E receptors, LPS receptors and scavenger receptors of macrophages (monocytes); the increased level of free fatty acids in the LPS/LDL complex may accelerate its subsequent catabolism.

Mol Gen Genet, 1989 Mar, 216(1), 164 - 9
DNA sequence of the metC gene and its flanking regions from Salmonella typhimurium LT2 and homology with the corresponding sequence of Escherichia coli; Park YM et al.; The DNA sequence of the Salmonella typhimurium metC gene and its flanking regions was determined . The metC gene contains an open reading frame of 1185 nucleotides encoding a polypeptide of 395 amino acids with a predicted molecular weight of 42,874 daltons . S1 nuclease mapping experiments located the transcription start site of the metC gene . The nucleotide sequence and the deduced amino acid sequence for the metC genes of S . typhimurium and Escherichia coli were compared . Although there are 279 nucleotide replacements, most do not change the amino acid sequence . Nucleotide sequence analysis of the flanking regions of the S . typhimurium metC gene shows that there is an open reading frame upstream and an open reading frame downstream of the gene . The existence of the divergently transcribed upstream open reading frame (designated ORF1) was confirmed by the construction of an ORF1-lacZ fusion . The transcription start site of ORF1 was determined by S1 nuclease mapping.

Mutagenesis, 1989 Mar, 4(2), 126 - 32
A study of the heterogeneity of bacterial fluctuation-test data and the effects of auxotrophic-growth enhancement; Bosworth D et al.; Microtitre fluctuation tests using Salmonella typhimurium TA100 and TA98 and Escherichia coli WP2uvrApKM101 were performed to determine the heterogeneity of spontaneous mutagenicity data and how this affects interpretation of results . Assays were performed in the absence and presence of additional amino acids to simulate the effects of the auxotrophic growth enhancement characteristic of tests of complex biological mixtures . The results indicate that the heterogeneity of the data did not depart significantly from that expected from binomial theory and that two criteria must be satisfied in order to define a positive result: (i) a net increase which significantly exceeds the background mutation and which takes account of its heterogeneity; and (ii) a statistically significant dose response.

Mutagenesis, 1989 Mar, 4(2), 115 - 25
Evaluation of the mutagenicity of azo dyes in Salmonella typhimurium: a study of structure-activity relationships; Shahin MM; In order to explore structure-activity relationships, 4,4'-diaminoazobenzene and four structurally related azo dyes were tested for their ability to induce gene mutations in Salmonella typhimurium strains TA1535, TA100, TA1537, TA1538, and TA98 . Only 4,4'-diaminoazobenzene and 4,4'-N(beta-hydroxyethylamino)azobenzene were found to be active in the two frameshift strains TA1538 and TA98 . Further tests were performed in strain TA98, both in the presence and in the absence of Aroclor 1254-induced rat or hamster liver S9 preparations . The amount of S9 used per plate was 50, 100, 150 or 300 microliters, which corresponds to 10, 20, 30 or 60% of S9 in S9 mix . 4,4'-Diaminoazobenzene was found to be mutagenic, and its mutagenicity depended on the percentage of S9 in S9 mix and the type of S9 fraction used . 4,4'-N-(beta-Hydroxyethylamino)azobenzene was less mutagenic than 4,4'-diaminoazobenzene, indicating a reduction in mutagenicity associated with the beta-hydroxyalkyl substituents . The other three azo dyes {4'-methyl-4-N,N-di(beta-hydroxyethylamino) azobenzene; 4'-amino-6-methyl-4-N,N-di(beta-hydroxyethylamino)azobenzene; and 4'-N(beta-hydroxyethyl-amino)4-N,N-di(beta-hydroxyethylamino)azobe nzene} were inactive, both in the presence and in the absence of the metabolic activation system . The use of the preincubation test did not alter the observed positive or negative response of these compounds . The importance of this finding is that the non-mutagenicity or decreased mutagenicity of these four compounds is predictable on the basis of their chemical structures . These azo dyes, like the non-mutagenic members of series of monocyclic aromatic amines, contain large substituents on one or both of the amino groups of the parent compound, in this case 4,4'-diaminoazobenzene . From our earlier data and the experiments discussed in this paper, we conclude that the study of structure--activity relationships can provide useful information for the prediction and interpretation of mutagenic responses.

FEMS Microbiol Lett, 1989 Mar, 49(1), 49 - 54
Occurrence of Salmonella typhimurium virulence plasmid-specific sequences in different serovars of Salmonella; Korpela K et al.; We have subcloned the 96-kilobasepair (kb) virulence plasmid, pLT2, of Salmonella typhimurium line LT2 into 7 subfragments . Using these subclones as probes, 35 independent Salmonella isolates were tested for complementary DNA sequences Sequences homologous to pLT2 were present in 15 of the isolates . All of these contained sequences homologous to at least one specific probe representing 15 kb of pLT2 . The traT gene from pLT2 was absent in 6 of these 15 isolates . Three strains reported to be cured of the plasmid were shown to harbour some sequences with homology to the pLT2 plasmid . Seven isolates were shown to contain homologous sequences with pBR322 but not with the pLT2 plasmid.

Eur J Biochem, 1989 Mar 1, 180(1), 23 - 32
Purification and characterization of a methionine-specific aminopeptidase from Salmonella typhimurium; Wingfield P et al.; An aminopeptidase specific for methionine (peptidase M) has been purified from wild-type and mutant Salmonella typhimurium strains . Recombinant peptidase M was also purified from Escherichia coli . These preparations were characterized with respect to their physicochemical properties using analytical ultracentrifugation, SDS/PAGE, isoelectric focusing, titration curve analysis, amino acid analysis, N-and C-terminal sequencing and various spectroscopic methods . Peptidase M activity is stimulated by Co2+, in agreement with previous studies using crude extracts of Salmonella . The purified preparations did not contain significant amounts of any metal . Enzymically important metal is loosely associated and lost during enzyme purification . Peptidase M was shown to contain seven free sulphydryl residues none of which are involved in either intra-or inter-molecular disulphide bonds . Most appear solvent-accessible as evidenced by their reactivity under native conditions . Limited modification of the sulphydryl residues with either iodoacetamide or 5,5'-dithiobis(2-nitrobenzoic acid) led to inactivation . Several cysteines were shown to be labelled to various degrees by peptide mapping of inactivated S-{14C}carboxymethylated protein . Whether cysteine modification affects enzymic activity directly (blocking an active site) or indirectly (by causing conformational change) remains to be established.

Eur J Biochem, 1989 Mar 1, 180(1), 133 - 41
Identification and localization of the membrane-associated, ATP-binding subunit of the oligopeptide permease of Salmonella typhimurium; Gallagher MP et al.; The OppF protein, a component of the oligopeptide permease of Salmonella typhimurium, is an ATP-binding protein and is believed to couple ATP hydrolysis to the transport process . This protein is an example of a large family of closely related proteins which couple ATP to a variety of different biological processes . The oppF gene has been cloned and sequenced . In order to identify and characterize its protein product we overproduced the protein from the cloned gene . Anti-OppF antibodies were raised against a synthetic peptide . Using these antibodies as a probe we identified OppF in wild-type and overproducing strains . Protease accessibility studies showed the protein to be a peripheral membrane protein located on the cytoplasmic side of the inner membrane . These findings have general implications for the organization and function of this class of prokaryotic and eukaryotic transport system.

Res Vet Sci, 1989 Mar, 46(2), 153 - 9
Relative importance of Salmonella-specific antibody isotypes in phagocytosis of Salmonella typhimurium by ovine mammary neutrophils; Mukkur TK et al.; The comparative opsonic efficiency of ovine salmonella-specific antibody isotypes was determined by measurement of specific phagocytic uptake of opsonised virulent Salmonella typhimurium by ovine mammary neutrophils . An in vitro phagocytosis assay revealed that IgM was superior to IgG2 in promoting the phagocytosis of opsonised virulent organisms . IgG1, on the other hand, was non-opsonic . Superiority of the IgM isotype over IgG2 as an opsonin was also evident in studies on the viability of opsonised S typhimurium upon phagocytosis . It was revealed that the percentage of organisms killed was appreciably greater when opsonisation was carried out with the IgM than with the IgG2 isotype, although after ingestion by neutrophils there was essentially no difference in the efficiency with which the ingested organisms were killed.

Mutat Res, 1989 Mar, 225(3), 75 - 82
Mutagenicity of nitro- and amino-substituted phenazines in Salmonella typhimurium; Watanabe T et al.; The nitro- and amino-substituted phenazines were synthesized and assayed for their mutagenicity in Salmonella typhimurium strains TA98 and TA98NR . Of 7 tested nitrophenazines, 4 were mutagenic in the absence of a microsomal metabolic activation system (S9 mix) and were more mutagenic in TA98 than in TA98NR . The order of mutagenicity of nitrophenazines in TA98 is 1.7- less than 2- less than 2.8- less than 2.7-substituted phenazine . Of 7 tested amino derivatives, 4 exhibited mutagenic activity with S9 mix in TA98 . 1-Nitro-, 1-amino, 1.6-dinitro-, 1.9-dinitro-, 1.6-diamino- and 1.9-diamino-phenazine were not mutagenic . As regards the relationship between mutagenic potency and chemical structure of the phenazines, the results suggested that structural requirements favoring mutagenic activity were the presence of substituents at the 2 and/or 7 position . Furthermore, 2.7-disubstituted phenazines were extremely mutagenic, 2.7-dinitrophenazine and 2.7-diaminophenazine induced 36,450 and 12,110 rev./nmole, respectively . In the preliminary study, 2.7-diaminophenazine was identified by gas chromatography/mass spectrometry from the reaction mixture of m-phenylenediamine and hydrogen peroxide.

Mutat Res, 1989 Mar, 222(3), 237 - 44
Genotoxicity and genotoxic enhancing effect of tetrandrine in Salmonella typhimurium; Whong WZ et al.; Tetrandrine has been used for the treatment of silicosis in China . The potential genotoxic and carcinogenic hazards of this drug were studied using the Salmonella/histidine reversion assay and the SOS/Umu test . The results show that tetrandrine was weakly mutagenic to Salmonella typhimurium TA98 with metabolic activation and did not induce SOS response . However, tetrandrine increased the mutagenic activity of benzo{alpha}pyrene, trinitrofluorenone (TNF), 2-aminoanthracene (2AA), diesel emission particles, airborne particles, and cigarette smoke condensate by more than 100%; the activity of aflatoxin B1 and fried beef was increased by over 75% . It also increased the 2AA and TNF-induced SOS response by more than 300% . These results indicated that tetrandrine was a weak promutagen inducing frameshift mutations and was a potent genotoxic enhancer . The mechanism for the genotoxic enhancement is not known . However, the fact that the increase in mutagenicity was noted only in TA98 and not in TA1538 suggested that the enhancement of genotoxicity by tetrandrine may result from an increase in error-prone DNA repair.

Mutat Res, 1989 Mar, 222(3), 161 - 6
Influence of the Uvr repair system on the mutagenicity of antiparasitic drugs; Espinosa-Aguirre JJ et al.; One amebicide (chloroquine diphosphate) and 2 anthelmintic compounds (niclosamide and pyrvinium pamoate) were found to be mutagenic for Salmonella typhimurium TA1537, TA1538, TA100 and TA98 Uvr- strains respectively . Drugs tested on homologous Uvr+ strains (TA1977, TA1978, UTH8414 and UTH8413) showed decreased mutagenic activity of the compounds . This indicates that premutational damage induced by the drugs was totally or partially repaired . Furthermore, results obtained in the present study suggest that niclosamide and pyrvinium pamoate induce premutational lesions by adduct formation, and that chloroquine diphosphate, known as an intercalating agent, behaves as an adduct-forming compound as regards its effects on Uvr- and Uvr+ S . typhimurium strains.

Mutat Res, 1989 Mar, 222(3), 141 - 8
Antimutagenicity of some citrus fruits in Salmonella typhimurium; Bala S et al.; The antimutagenic effect of 10 citrus fruit juices was observed against the mutagenicity of N-nitro-o-phenylenediamine (NPD) in TA97a and sodium azide in TA100 tester strains of Salmonella typhimurium using the Ames test . It was noticed that the juices of all these fruits reduced significantly the NPD and sodium azide induced revertant colonies . The inhibitory activity was enhanced if the mutagen and juice were co-incubated for about 30 min at 37 degrees C prior to performing the mutagenicity assay . Dilution with distilled water led to the reduction in the inhibitory activity . The antimutagenic activity of synthetic ascorbic acid or citric acid or combined ascorbic acid and citric acid was also seen . But the results with fruit juices tempted us to believe that in addition to ascorbic acid and citric acid, the presence of other factor(s) possessing antimutagenic properties cannot be ruled out.

Biochim Biophys Acta, 1989 Mar 1, 1007(2), 196 - 202
Immunochemical identification of a tRNA-independent cytokinin-like compound in Salmonella typhimurium; Blum PH et al.; Chemical and immunological characterization of Salmonella typhimurium cell extracts indicates that this organism produces a molecule which closely resembles the plant growth regulator, cytokinin . Alcohol-soluble cationic ultraviolet-absorbing material was fractionated by reverse-phase HPLC using gradient conditions optimized previously for modified nucleoside separation . A single hydrophobic compound was identified in the cytokinin region of the gradient, and limited quantities of the compound were prepared by HPLC fractionation of crude extracts . The compound demonstrated significant activity in a radioimmunoassay for cytokinins which detects N6-isopentenylated adenine derivatives . Boronate affinity chromatography indicated the compound is likely to be ribosylated and therefore a nucleoside . These and other tests indicate the compound has the most notable structural characteristics of a cytokinin . Spectral analysis and chromatographic comparison with cytokinin standards indicate the compound also has some unique structural features . Presence of the compound in extracts of an S . typhimurium mutant blocked for synthesis of tRNA-derived cytokinins excluded tRNA as a source for the compound and implicates existence of a tRNA-independent pathway for cytokinin biosynthesis in this bacterial species.

Infect Immun, 1989 Mar, 57(3), 850 - 7
Sequence analysis of rsk, a portion of the 95-kilobase plasmid of Salmonella typhimurium associated with resistance to the bactericidal activity of serum; Vandenbosch JL et al.; Increased sensitivity to killing by human serum complement occurs in Salmonella typhimurium strains in which the 95-kilobase virulence plasmid is integrated into the chromosome . This phenotypic change appears to be due to alterations in plasmid gene expression and is reversed by the presence of an autonomous plasmid bearing a cloned region of the virulence plasmid . Accordingly, this region has been termed rsk for reduced serum killing . Sequence analysis of the region reveals that rsk is composed of a series of direct 10-base-pair (bp) repeats with a 21-nucleotide periodicity . Two adjacent repeats are identical, but increasing loss of conservation is apparent with increased distance both 5' and 3' of these highly conserved 10-mers . The smallest isolated sequence which restores the serum-resistant phenotype is only 66 bp long and contains the two identical 10-mers and one degenerate 10-mer (8 of 10 bp conserved) 3' of these . The minimal rsk region of 66 bp does not appear to contain a coding sequence, or a promoter, for a structural gene . It is proposed that the minimal rsk is an isolated regulatory site involved in the regulation of the serum resistance of S . typhimurium . Integration of the 95-kilobase plasmid disrupts the normal regulation of virulence plasmid genes, resulting in an increase in the killing of the bacteria by complement activated by the classical pathway . The introduction of the minimal rsk on a multiple-copy plasmid restores resistance to serum killing, possibly through the titration of a trans-acting regulatory factor.

Kanagawa Shigaku, 1989 Mar, 23(4), 568 - 86
{The roles of macrophage on the mechanism of development of periapical lesion . The response of macrophage stimulated with bacteria isolated from infected root canals}; Tominaga N; It has been proposed that bacteria in infected root canals are most important agents to pathogenesis of the periapical lesion . The aim of the present study was to examine the roles of macrophage on the mechanism of development of periapical lesion . Therefore the influences of bacteria isolated from infected root canals to macrophage functions and the effects of products from macrophage stimulated with bacterial components to periodontal tissue were investigated . In this study, sonic extracts prepared from Bacteroides buccae predominantly isolated from root canals were tested for its capacity of induction of chemotaxis and production of prostaglandin E2 and collagenase from human peripheral monocyte . Furthermore prostaglandin E2, collagenase production and alkaline phosphatase activity of fibroblasts from human periodontal ligament (HPLF), pulp (HPF) and gingiva (Gin 1) stimulated with macrophage conditioned medium (MCM) stimulated with B . buccae sonic extracts were examined . The results obtained were as follows . The sonic extract of B . buccae showed capacity to induce macrophage chemotaxis directly and by activation of serum complement, and the serum activated with sonic extract of B . buccae was more active than the serum activated with LPS of Salmonella typhimurium . Prostaglandin E2 production of macrophage was increased when the cells were stimulated by sonic extracts of B . buccae, but collagenase activity . toas not increased . MCM stimulated with sonic extracts of B . buccae fot 48 hours strongly induced PGE2 and collagenase production from HPLF and HPF, at the same time sonic extract showed the similar capacity of induction of the PGE2 production of MCM . But, HPF stimulated with sonic extract showed the low activity of induction of the PGE2 production . On the other hand, Gin 1 cell produced a few amount of the PGE2 when it was stimulated with MCM, but not produced collagenase . Alkaline phosphatase activity of HPLF and HPF had been inhibited by addition of MCM stimulated with B . buccae sonic extract.

Kanagawa Shigaku, 1989 Mar, 23(4), 451 - 68
{Bacteriological and immunological studies on the mechanism of development of periapical lesion . Immunobiological activities and localization in periapical lesion of the cellular components from Bacteroides buccae}; Tani N; It has been strongly suggested that the periapical lesion develop as a result of immunopathological response to continuous antigenic stimulation . Bacteria from root canal systems might be most important pathogenesis capable of inducing immunological reactions in periapical tissue . The purpose of this study, therefore, was clarify the immunological potentials of Bacteroides buccae (B . buccae) which was frequently isolated from root canals with chronic periapical lesion . Biological activities of B . buccae cellular components, such as lipopolysaccharides (LPS) and cellular protein were investigated on the enhancement of monocytes migration induction of interleukin 1 (IL-1) production, mitogenicity and polyclonal B cell activation . The localization of immunocompetent cells and B . buccae in human chronic periapical lesions were examined by biotin-avidin-horseradish peroxidase method, and peroxidase antiperoxidase methods using monoclonal antibodies . Following results were obtained . 1 . On the lymulus lysafe clotting activity and Shwarzman activity of B . buccae LPS were about half of Salmonella typhimurium (S . typhimurium) . 2 . Both LPS and 38K protein preparations from B . buccae enhanced the activity of human peripheral monocytes migration and induced IL-1 production . 3 . It was found that mitogenicity of LPS from B . buccae on splenocytes of BALB/c and BALB/c nu/nu mice was weaker than that of 38K protein, however mitogenicity on thymocytes were not shown in both preparations . 4 . The polyclonal B cell activation on splenocytes of BALB/c nu/nu mice by B . buccae were remarkably induced by 38K protein, but LPS showed less activity elicit than 38K protein . 5 . It might be suggested that the both LPS and 38K protein of B . buccae may depend on the activities of macrophage and lymphocytes . 6 . Antigenic substance of B . buccae were found most commonly engulfed materials within macrophage and intercellular space in connective tissue . 7 . Dense accumulation of T and B lymphocytes were observed gathering around the phagocytic macrophage (foam cell), the number of B lymphocytes around the macrophage was greater than that of T lymphocytes . 8 . These findings indicated that both LPS and 38K protein from B . buccae have a wide regulation function of immunobiologic responses . Therefore, it was suggested that both LPS and 38K protein from B . buccae may play significant roles in the pathogenesis of periapical lesion.

FEMS Microbiol Immunol, 1989 Mar, 1(4), 229 - 35
Oral vaccination of rats with live avirulent Salmonella derivatives expressing adhesive fimbrial antigens of uropathogenic Escherichia coli; Schmidt G et al.; The avirulent Salmonella typhimurium F885 was transformed with a plasmid carrying the cloned S fimbriae genes of a uropathogenic Escherichia coli . The resulting transformant (F885-1) produced efficiently E . coli S fimbriae and was used for live oral vaccination of rats . For comparison rats were immunized subcutaneously with isolated S fimbriae . Both routes of vaccination resulted in a significant IgG antibody response to S fimbriae . In addition live oral vaccination induced a serum IgA response against S fimbriae . After transurethral infection of rats with a S fimbriae producing E . coli a 10-fold reduction of bacterial counts in the kidney was observed in rats orally vaccinated with F885-1 as compared to unvaccinated controls . This study suggests that the avirulent Salmonella F885 may be used as a fimbrial antigen carrier for oral vaccination against renal infections.

Mutagenesis, 1989 Mar, 4(2), 90 - 4
Studies of error-prone DNA repair in Escherichia coli K-12 and Ames Salmonella typhimurium strains using a model alkylating agent; Little CA et al.; 4-Acetoxy-3-acetoxymethyl acetophenone (AAMAP) is mutagenic in Ames Salmonella typhimurium tester strains TA100 and TA98, which carry plasmid pKM101, but not in the isogenic plasmid-less strains TA1535 and TA1538 . Similarly, no AAMAP-induced reversion of the his-4 allele is detectable in Escherichia coli K-12 umuC strains in the absence of the plasmid, even when the strains are treated with ethylene-diaminetetraacetate to increase permeability, or when the uvrB allele is introduced to increase error-prone DNA repair . AAMAP is, however, mutagenic in umuC+ strains or in umuC strains in which plasmid pKM101 has been introduced, suggesting that the plasmid-encoded MucAB or the chromosomally determined UmuDC proteins are required for mutagenesis . Mutation frequencies are higher in E . coli umuC (pKM101) strains, which resemble Ames tester strains of S . typhimurium, than in E . coli umuC+ or even umuC+ (pKM101) strains . Therefore, providing that the recommended pKM101-containing tester strains are used, the apparent absence of Umu-like protein activity in S . typhimurium may actually increase the sensitivity of the Ames test for the detection of mutagens that require error-prone DNA repair for activity.

Immunopharmacology, 1989 Mar-Apr, 17(2), 107 - 18
Murine macrophage activation with resorcyclic acid lactones (RALs): comparison with diethylstilbestrol and 17 beta-estradiol; Edwards CK 3rd et al.; Zearalane, a resorcyclic acid lactone (RAL) derivative, activates murine macrophages (M phi) in vivo and in vitro . Mouse M phi incubated in vitro with different concentrations of zearalane released superoxide anion (O2-) on stimulation with either opsonized zymosan (Op-zym), phorbol myristate acetate (PMA), or Salmonella typhimurium . The levels of O2- released were similar to those released from M phi incubated in vitro with supernatants enriched in macrophage-activating factors from concanavalin A-stimulated mouse spleen cells . In contrast, 17 beta-estradiol (E2) or diethylstilbestrol (DES) induced little or no enhancement of O2- release . Zearalane, dideoxyzearalane, DES and E2 were tested for induction of host resistance to S . typhimurium infection in mice . Treatment of mice with zearalane (9 mg/kg) resulted in at least 65% survival 4 days post-infection, compared to 10% survival of mice with vehicle alone, DES, or E2 . Peritoneal and alveolar M phi from the zearalane-treated mice released up to six times as much O2- on stimulation with Op-zym as M phi from the other treatment groups . M phi activation was observed for up to 7 days after intraperitoneal or subcutaneous administration of zearalane in either aqueous or organic vehicles . These results suggest that zearalane may enhance resistance to infection by increasing bactericidal activity due to increased release of toxic oxygen radicals by M phi and mononuclear phagocytes . These effects differ from the immunosuppressive effects reported for DES and E2.

Proc Natl Acad Sci U S A, 1989 Mar, 86(6), 1949 - 53
A region of a cyanobacterial genome required for sulfate transport; Green LS et al.; Using the cysA locus of Salmonella typhimurium as a heterologous probe, we have cloned a region of the Anacystis nidulans R2 (Synechococcus PCC 7942) genome involved in sulfate assimilation . The 8.3-kilobase-pair region encodes at least five transcripts that cannot be detected unless the cells are deprived of sulfur . One of the genes in this region has been sequenced, and the protein that it encodes is homologous to a polypeptide component of other permease systems of Escherichia coli and Salmonella . Insertional inactivation of the putative sulfate permease gene, designated cysA, as well as of other genes within this region, results in cysteine auxotrophy, reduced sulfate uptake, and altered expression of soluble and cytoplasmic-membrane polypeptides associated with sulfur starvation.

J Periodontal Res, 1989 Mar, 24(2), 88 - 95
LPS-elicited secretory responses in monocytes: altered release of PGE2 but not IL-1 beta in patients with adult periodontitis; Garrison SW et al.; Lipopolysaccharide responsiveness in human subjects was assessed through the examination of LPS-stimulated PGE2 and IL-1 beta release from counterflow isolated monocytes from patients with varying levels of periodontal destruction . This study was performed in order to investigate a possible relationship between LPS-mediated secretory responses in monocytes and susceptibility to periodontal destruction in humans . Subjects were chosen based on apparent resistance or susceptibility to disease as measured by little or no periodontal destruction versus generalized severe destruction, respectively . Because IFN-gamma can influence LPS-stimulated responses, the effect of IFN-gamma on the LPS-stimulated release of PGE2 and IL-1 beta was also assessed . Peripheral blood monocytes were separated by counterflow centrifugation and cultured (10(6)/ml/well) with control medium or medium containing LPS from Bacteroides gingivalis, B . intermedius, Actinobacillus actinomycetemcomitans, or Salmonella typhimurium, with or without 10 Units/ml recombinant IFN-gamma . Media were exchanged at 24 and 48 hours and culture supernatants assayed for both PGE2 and IL-1 beta by RIA . Patients classified as Susceptible to periodontitis demonstrated 2- to 3-fold greater PGE2 release than Resistant patients . This difference was observed with all LPS preparations over both the 0-24 hour and 24-48 h culture periods . IL-1 beta release, however, was not significantly different between patient groups . IFN-gamma did not affect the LPS-stimulated release of PGE2 but significantly enhanced the release of IL-1 beta . The IFN-gamma effects were similar for both patient groups . These findings indicate that LPS-stimulated PGE2 release from peripheral blood monocytes may correlate with susceptibility to periodontitis in human subjects.

Chem Res Toxicol, 1989 Mar-Apr, 2(2), 114 - 2
Comparison of rates of enzymatic oxidation of aflatoxin B1, aflatoxin G1, and sterigmatocystin and activities of the epoxides in forming guanyl-N7 adducts and inducing different genetic responses; Baertschi SW et al.; The genotoxicity of the dihydrofurans aflatoxin B1 (AFB1), aflatoxin G1 (AFG1), and sterigmatocystin (STG) was examined in a bacterial system in which the induction of SOS repair is monitored with the umuC gene linked to a lacZ reporter gene in plasmid pSK1002 . Human liver microsomal cytochrome P-450NF oxidized the dihydrofurans (in the presence of calf thymus DNA) to give guanyl-N7 adducts in the order AFB1 greater than STG greater than AFG1 . The order of the umu response seen was STG greater than AFB1 greater than AFG1, when either the dihydrofurans were activated enzymatically or the synthetic epoxides of the dihydrofurans were added directly to the bacteria . Thus, the umu response per molecule of guanyl-N7 DNA adduct follows the order STG greater than AFB1 greater than AFG1 . A similar pattern has been reported in the literature for Salmonella typhimurium base substitution dependent his reversions, but the pattern AFB1 greater than STG greater than AFG1 has been found for bacterial frame-shift-dependent mutagenesis and hepatocarcinogenesis . The guanyl-N7 adduct derived from AFG1 has considerably less of all of these biological activities per molecule . Neither guanine imidazole ring opening nor apurinic site formation appears to be a factor involved in the differential biological responses seen with the three guanyl-N7 adducts . These findings indicate that these structurally related guanyl-N7 DNA adducts have intrinsic differences which give rise to divergent biological responses.

Mutat Res, 1989 Mar, 211(1), 139 - 45
Effects of prototypic PCBs on benzo{a}pyrene mutagenic activity related to vitamin A intake; Grolier P et al.; The effects of vitamin A dietary intake (2 and 20 IU */g of food) on the mutagenic activity of benzo{a}pyrene (B(a)P) toward Salmonella typhimurium (TA98) were studied either in control rats or in animals treated by the PCB congeners 2,4,5,2',4',5'-hexachlorobiphenyl {2,4,5)2Cl) and 3,4,3',4'-tetrachlorobiphenyl {3,4)2Cl) . (3,4)2Cl (a planar compound) strongly increased B(a)P monooxygenase (B(a)PMO) activity and glutathione transferase, (2,4,5)2Cl (a non-planar PCB) was a strong inducer of epoxide hydrolase and a weak inducer of B(a)PMO . Enzyme induction was not modified by changes in vitamin A dietary intake . A higher mutagenic effect was observed in the (3,4)2Cl group than in the (2,4,5)2Cl one . This could be related to the specific form of cytochrome P-450 induced by (3,4)2Cl . In the untreated animals, the activation of B(a)P was higher in the 2-IU group than in the 20-IU one . Conversely, in PCB-treated rats the mutagenic activity of B(a)P was higher in the 20-IU group than in the 2-IU one . PCB induction increased the liver content of vitamin C in both the 2-IU and the 20-IU groups but only increased the glutathione levels in the 2-IU groups . This suggests that glutathione content in cellular fractions may be one of the determining parameters for the mutagenic activity of B(a)P.

Clin Exp Immunol, 1989 Mar, 75(3), 365 - 70
Response of synovial fluid T cell clones to Yersinia enterocolitica antigens in patients with reactive Yersinia arthritis; Hermann E et al.; From synovial fluids of two patients with reactive arthritis following Yersinia enterocolitica infection, T lymphocyte clones were obtained that showed proliferative responses to Y . enterocolitica . The responses required autologous T-cell-depleted peripheral blood mononuclear cells as antigen presenting cells . Three clones were studied in detail; two of them showed a marked and specific response to Yersinia antigens alone, the other one recognized both Yersinia and Salmonella typhimurium antigens . The antigen-specific proliferation of the clones could be completely blocked by monoclonal antibodies to HLA-DR . These experiments show that synovial T lymphocytes presumably involved in the in situ immune response to microbial antigens triggering reactive arthritis can be cloned directly from the site of inflammation.

Science, 1989 Feb 24, 243(4894 Pt 1), 1059 - 62
A Salmonella locus that controls resistance to microbicidal proteins from phagocytic cells; Fields PI et al.; Facultative intracellular pathogens pose an important health problem because they circumvent a primary defense mechanism of the host: killing and degradation by professional phagocytic cells . A gene of the intracellular pathogen Salmonella typhimurium that is required for virulence and intracellular survival was identified and shown to have a role in resistance to defensins and possibly to other microbicidal mechanisms of the phagocyte . This gene may prove to be a regulatory element in the expression of virulence functions.

Nature, 1989 Feb 23, 337(6209), 745 - 9
Three-dimensional structure of CheY, the response regulator of bacterial chemotaxis; Stock AM et al.; Homologies among bacterial signal transduction proteins suggest that a common mechanism mediates processes such as chemotaxis, osmoregulation, sporulation, virulence, and responses to nitrogen, phosphorous and oxygen deprivation . A common kinase-mediated phosphotransfer reaction has recently been identified in chemotaxis, nitrogen regulation, and osmoregulation . In chemotaxis, the CheA kinase passes a phosphoryl group to the cytoplasmic protein CheY, which functions as a phosphorylation-activated switch that interacts with flagellar components to regulate motility . We report here the X-ray crystal structure of the Salmonella typhimurium CheY protein . The determination of the structure was facilitated by the use of site-specific mutagenesis to engineer heavy-atom binding sites . CheY is a single-domain protein composed of a doubly wound five-stranded parallel beta-sheet . The phosphoacceptor site in CheY is probably a cluster of aspartic-acid side chains near the C-terminal edge of the beta-sheet . The pattern of sequence similarity of CheY with components of other regulatory systems can be interpreted in the light of the CheY structure and supports the view that this family of proteins have a common structural motif and active site.

Biochemistry, 1989 Feb 21, 28(4), 1814 - 9
Relationship between guanosine tetraphosphate and accuracy of translation in Salmonella typhimurium; Negre D et al.; In bacteria a high level of mistranslation is observed in amino acid starved rel-, but not rel+, strains, and mistranslation can be studied qualitatively by means of "stuttering" experiments in two-dimensional protein gels . It has been suggested that the low level of mistranslation that occurs in rel+ strains is assured by guanosine 5'-diphosphate 3'-diphosphate (ppGpp), a nucleotide whose intracellular concentration greatly increases in rel+ cells under amino acid starvation . In the present study the relationship between level of ppGpp and mistranslation was analyzed by performing stuttering experiments in amino acid starved bacteria that contained either high or low levels of ppGpp . Three strains of Salmonella typhimurium were used in these experiments: a relA+ hisT+ strain (TA997), a relA+ hisT strain (TA1001), and a relA hisT strain (PD2) . These strains were first characterized with respect to macromolecular syntheses and ppGpp levels under exponential growth and under amino acid starvation . Both rel+ strains exhibited stringent control over RNA synthesis . ppGpp accumulated to high levels when TA997 was starved for either of three amino acids . Starvation of TA1001 for histidine did not cause accumulation of ppGpp, whereas starvation for lysine and arginine produced high levels of ppGpp . Extracts from the three strains, obtained either under exponential growth or under amino acid starvation, were then subjected to two-dimensional electrophoretic anaylsis: mistranslation was observed whenever ppGpp was absent . In particular, starvation of TA1001 for histidine resulted in high mistranslation frequencies, while under lysine and arginine starvation mistranslation was undetectable, regardless of whether the cells were rel+ or rel-.(ABSTRACT TRUNCATED AT 250 WORDS)

Arch Biochem Biophys, 1989 Feb 15, 269(1), 25 - 31
Dichlorobenzidine-DNA binding catalyzed by peroxidative activation in Salmonella typhimurium; DeBruin LS et al.; Peroxidative oxidation of dichlorobenzidine in vitro results in covalent binding to exogenous DNA . In a modified Ames assay, mutagenicity is observed in S . typhimurium strain TA98 following the incubation of dichlorobenzidine, bacteria, and hydrogen peroxide . In this paper, we demonstrate that {14C}dichlorobenzidine becomes covalently bound to S . typhimurium macromolecules, including DNA, when exogenous hydrogen peroxide is supplied . We compared the levels of binding in a pair of otherwise isogenic strains with wild-type (oxyR+) versus constitutive (oxyR1) expression of the hydrogen peroxide stress-induced regulon . Binding was approximately twofold higher in TA4124 (oxyR1) than in TA4123 (oxyR+) . Bacterial hydroperoxidases may catalyze the activation of dichlorobenzidine to mutagenic and DNA binding species in this system.

Cancer Res, 1989 Feb 15, 49(4), 853 - 6
Prostaglandin H synthase-dependent mutagenic activation of benzidine in a Salmonella typhimurium Ames tester strain possessing elevated N-acetyltransferase levels; Josephy PD et al.; Watanabe and colleagues (Biochem . Biophys . Res . Commun . 147: 974-979, 1987) have constructed plasmid-containing derivatives of Salmonella typhimurium Ames tester strain TA1538 with high levels of acetyltransferase activities . In this paper, we describe the mutagenic response of one of these strains, TA1538/1,8-DNP6 (pYG 121), to the bladder carcinogen benzidine and other arylamines . Strain TA1538/1,8-DNP6 (pYG 121) was far more sensitive to benzidine than any previous tester strain, following metabolism of the aromatic amine by hamster hepatic S9, ram seminal vesicle microsomal preparation (RSVM), or purified prostaglandin synthase . Therefore, bacterial acetyltransferase-dependent metabolism of a proximate mutagen is implicated in each of these systems . The mechanism of RSVM-dependent activation of benzidine was examined further . The arachidonic acid-independence and indomethacin insensitivity previously noted with strain TA98 were also observed with the new tester strain . We confirmed that prostaglandin H synthase is the enzyme activity responsible for activation of benzidine by RSVM . Purified prostaglandin H synthase holoenzyme, or apoenzyme reconstituted with heme, supported benzidine activation . However, apoenzyme reconstituted with manganese protoporphyrin IX, which yields enzyme having cyclooxygenase activity but not peroxidase activity, was inactive . Addition of catalase inhibited, and addition of exogenous hydrogen peroxide increased, RSVM-mediated benzidine mutagenicity . We propose that hydrogen peroxide released by the tester strain bacteria (rather than arachidonic acid-derived peroxide) is the oxidizing agent which supports prostaglandin H synthase peroxidase activity in Ames test systems.

J Mol Biol, 1989 Feb 5, 205(3), 519 - 28
Image reconstruction of the flagellar basal body of Salmonella typhimurium; Stallmeyer MJ et al.; The basal body is thought to be a part of the rotary motor of the bacterial flagellum . It consists of a central rod coaxial with a set of four rings, which are associated with the cell envelope . We used single-particle averaging methods to analyze images of negatively stained basal bodies of Salmonella typhimurium . Several averages were computed, so that the reliability of features could be assessed . We carried out the same analysis on electron micrographs of isolated, negatively stained L-P rings . In order to interpret the averages in terms of a three-dimensional structure, we carried out image reconstruction on them . The resulting three-dimensional map corresponds to the cylindrically averaged structure of the basal body . To show that the reconstruction procedure is legitimate, we demonstrate it on model data . The results of the modelling show that features very near to the axis of the reconstruction are not reliable but that broader, off-axis features are represented faithfully . The L ring is L-shaped, with the long arm of the L parallel to the axis of the rod, and the short arm pointing away from the rod . The P ring, on the other hand, appears to be a ring or disk . The position of the L-P ring complex on the rod seems to vary somewhat, consistent with its putative role as a bushing . The cross-sectional shape of the S ring is that of a frustum rather than a disk . The M ring, which is oval in cross section, sits atop the S ring, making contact with it at an outer radius . The S ring appears to make contact with the rod, whereas the M ring does not . This situation, if true, is difficult to reconcile with the common notion that the S ring is stationary and the M ring rotates . It seems more likely that the S ring and rod rotate as a unit.

J Natl Cancer Inst, 1989 Feb 1, 81(3), 223 - 7
Selective mutagenic activation by cytochrome P3-450 of carcinogenic arylamines found in foods; Snyderwine EG et al.; Heterocyclic arylamines found in cooked foods including fish and beef are potent mutagens and carcinogens . The purpose of this investigation was to determine the specificity of cytochromes P1-450 and P3-450 toward the metabolic activation of these arylamines . We used a novel mutagenicity test system which combined human cells expressing either recombinant cytochrome P1-450 or P3-450 with Salmonella typhimurium to score mutants . Cytochrome P3-450, a single isoform of the cytochrome P-450 supergene family, bioactivated these food mutagens . Cytochrome P1-450 showed little or no activation of these arylamines but was the isoform predominantly responsible for the activation of the aromatic hydrocarbon benzo{a}pyrene-7,8-diol . This assay system should serve to define the specificities of individual cytochromes P-450 in the metabolic activation of carcinogens.

Acta Ophthalmol (Copenh), 1989 Feb, 67(1), 69 - 74
Early morphological changes of intracellular bacteria in Salmonella typhimurium infection of the guinea pig conjunctival epithelium; Latkovic S et al.; Conjunctival epithelium of the guinea pig was incubated with a virulent strain of Salmonella typhimurium 395 MS for 1 h . Intracellular bacteria were observed in superficial and intermediate cell layers, but not in basal cells . The majority of the bacteria were located within primary or secondary phagosomes; a few were seen free in the cytoplasm . A number of intraphagosomal bacteria showed morphological signs of degradation . Ultrastructurally, the initial phases of Salmonella typhimurium infection of the guinea pig conjunctival epithelium appear to be consistent with endocytic uptake of bacteria by the epithelial cells, followed by their degradation in secondary phagosomes . The conjunctival epithelial cells seem able to inactivate a certain number of virulent bacteria and thus, to a degree, to control the infection in its early phase with defence mechanisms pertaining to the cells themselves, without support from the professional phagocytic cells.

Antimicrob Agents Chemother, 1989 Feb, 33(2), 192 - 7
Escherichia coli susceptible to glycopeptide antibiotics; Shlaes DM et al.; Mutants of Escherichia coli susceptible to vancomycin were isolated after mutagenesis with nitrosoguanidine . One such mutant was studied extensively . Multiple regression analysis of the relationship between physical properties of 20 glycopeptides and their in vitro activities against the vancomycin-susceptible mutant revealed a significant correlation with molecular mass (P = 0.007) . pI, hydrophobicity, and affinity of the glycopeptide for the pentapeptide target were not as important for activity . This suggested that a block of access of the antibiotic to its target could be the major factor determining activity . Outer membrane proteins of the vancomycin-susceptible mutant, resistant parent, and revertant strains appeared normal . The mutant exhibited increased susceptibility to both erythromycin and fusidic acid which was lost in single-step revertants to vancomycin resistance . Polymyxin B nonapeptide was synergistic with erythromycin and fusidic acid against the parent and revertant but not against the susceptible mutant . Analysis of the susceptibilities of control strains of E . coli and Salmonella typhimurium with known defects in lipopolysaccharide (LPS) synthesis revealed that core LPS mutants (Re chemotype) were phenotypically similar to the E . coli mutant under study . However, the LPS core of the mutant migrated slightly less rapidly on sodium dodecyl sulfate-polyacrylamide gel electrophoresis than wild-type or revertant core LPS and did not resemble Re chemotype LPS core obtained from Salmonella rfaC and rfaD mutants . These data suggest that defects in LPS core structure other than loss of heptose moieties may also be important in loss of resistance to large, hydrophilic molecules such as glycopeptides.

J Trop Pediatr, 1989 Feb, 35(1), 35 - 9
Salmonella septicaemias in Kenyan children; Nesbitt A et al.; In a 5-month study of Salmonella septicaemias in Kenyan children carried out during the annual peak infection period, Salmonella typhimurium septicaemias occurred seven times more frequently than typhoid or other non-typhoid infections . Salmonella typhimurium infections were predominantly community acquired, malnourished infants from rural malaria endemic areas with poor water supply were especially vulnerable . Typical clinical features of fever, diarrhoea, and severe anaemia resembled P . falciparum malaria which often co-existed . Mortality was 18 per cent . Isolates exhibited a wide range of multidrug resistance . Typhoid affected older children, was less severe and drug sensitive.

J Appl Bacteriol, 1989 Feb, 66(2), 127 - 35
An improved ELISA method for the detection of Salmonella typhimurium; Prusak-Sochaczewski E et al.; The applicability of enzyme-linked immunosorbent assay (ELISA) for the detection of salmonellas in foodstuffs was investigated . Several factors affecting the sensitivity of the ELISA, such as the type of protein used for plate post-coating, the method of antibody labelling, and accelerators for antigen-antibody and enzyme-substrate reactions, were studied . Labelling of the antibody with horseradish peroxidase and the use of o-phenylenediamine as substrate in the detection system were demonstrated to be most suitable for the enzyme assay . Based on these findings, an improved ELISA method was developed for the detection of Salmonella typhimurium . The improved technique was able to detect as few as 5 x 10(4)-10(5) cell/ml of salmonellas, and about 24 h were required to enrich the bacteria in food samples and to perform the test . With some modifications, the ELISA assay could reach a very high level of sensitivity and provide excellent reproducibility.

Eur J Cancer Clin Oncol, 1989 Feb, 25(2), 255 - 61
Mutagenicity profiles of newer amsacrine analogues with activity against solid tumours: comparison of microbial and mammalian systems; Ferguson LR et al.; Amsacrine, an acridine derivative used clinically in the treatment of acute leukaemia, has formed the basis for the development of further compounds with high activity against experimental solid tumours, one of which is currently in clinical trial . We have compared the ability of these drugs to cause point mutations in bacteria, 'petite' mutations in yeast and mutations in mammalian cells . Several of the compounds are frameshift mutagens in Salmonella typhimurium TA1537 while some cause 'petite' mutagenesis in Saccharomyces cerevisiae . All are highly clastogenic and have significant mutagenic activity at the 6-thioguanine locus in cultured V79 Chinese hamster fibroblasts following 1 h drug exposures . None are mutagenic at the ouabain locus of these cells . The relationship between different indicators of mutagenicity has been studied using an additional set of amsacrine analogues, some of which are mutagenic in S . typhimurium TA98 . There is a highly significant relationship between mutation frequency (measured as resistance to 6-thioguanine) and either cytotoxicity (D37 values in a clonogenic assay) or clastogenicity (ability to induce micronuclei) . However, there is no correlation with mutagenicity in microbial systems . The results suggest that the cytotoxicity, clastogenicity and mutagenic activity of the amsacrine analogues is mediated by similar mechanisms, probably involving the enzyme DNA topoisomerase II.

Cancer Lett, 1989 Feb, 44(2), 109 - 16
Characterization and mutagenicity of 1-nitrosotryptophol and 6-nitrotryptophol possible genotoxic substances associated with smoking and alcohol consumption; Tanaka K et al.; Tryptophol (Typ) is a minor product of tryptophane metabolism in humans which is increased with alcohol consumption . Typ can react rapidly with nitrite at pH 3.0 to form 1-nitrosotryptophol (NO-Typ) in high yield . This product is also formed in various organic solvents by the reaction of NO/NO2 mixtures with Typ . Under similar conditions, NO2 in the absence of NO will react with Typ to form 6-nitrotryptophol (NO2-Typ) . Both products, NO-Typ and NO2-Typ, are mutagenic when tested in the absence of rat liver microsomes with a variety of Salmonella typhimurium tester strains.

Mutat Res, 1989 Feb, 216(1), 27 - 33
Azidoalanine mutagenicity in Salmonella: effect of homologation and alpha-methyl substitution; Mangold JB et al.; Azide mutagenicity in susceptible non-mammalian systems involves the requisite formation of L-azidoalanine, a novel mutagenic amino acid . The biochemical mechanism(s) of azidoalanine-induced mutagenesis, however, is not known . Previous studies of the structural requirements for azidoalanine mutagenicity suggested the importance of free L-amino acid character, and that bioactivation of azidoalanine to the ultimate mutagenic species is required . To gain more insight into possible enzymatic processing, the alpha-methyl analogue, alpha-methyl-azidoalanine, and the homologue, 2-amino-4-azidobutanoic acid, were synthesized and tested for mutagenic potency in Salmonella typhimurium strain TA1530 . In addition, azidoacetic acid, a possible azidoalanine metabolite, was prepared and tested . The results show that alpha-methyl substitution effectively blocks the mutagenic effects of azidoalanine with alpha-methyl-azidoalanine being nearly devoid of mutagenic activity . In contrast, homologation of azidoalanine to yield 2-amino-4-azidobutanoic acid produces a marked increase in molar mutagenic potency . As with azidoalanine, the mutagenic activity of this homologue is associated with the L-isomer . Azidoacetic acid, however, was only very weakly mutagenic when tested as either the free acid or ethyl ester . This low mutagenic potency may indicate that bioactivation does not involve the entry of azide-containing azidoalanine catabolite into the Kreb's cycle . The high potency of 2-amino-4-azidobutanoic acid may be indicative of more efficient bioactivation and/or greater intrinsic activity . Importantly, the latter finding clearly shows that potent azido-amino acid mutagenicity is not limited to azidoalanine alone.

Epidemiol Infect, 1989 Feb, 102(1), 113 - 8
Persistent and transient clones of Salmonella typhimurium of phage type 141 recognized by biotyping; Old DC et al.; Among the 81 cultures of Salmonella typhimurium of phage type 141 examined, 72 had been isolated from Sheffield incidents in 1984-5 and 9 were Scottish isolates from 1986-7 . All of these cultures from diverse sources belonged to primary biotype 31; 79 were of full biotype 31beg and 2 anaerogenic cultures were of full biotype 31begj . This is the first known occasion on which an epidemic strain of S . typhimurium of phage type/biotype 141/31beg has been implicated in outbreaks of human or animal infection in the UK . Because previous epidemic strains of S . typhimurium of phage type 141 in the UK belonged to biotypes 1f and 9f which are phylogenetically unrelated to biotype 31beg, the likely origin of this most recent epidemic S . typhimurium strain of phage type/biotype 141/31beg is discussed.

J Clin Microbiol, 1989 Feb, 27(2), 261 - 5
Detection of enterotoxigenic Escherichia coli after polymerase chain reaction amplification with a thermostable DNA polymerase; Olive DM; The direct identification of enterotoxigenic Escherichia coli from clinical specimens was examined by using the polymerase chain reaction (PCR) for amplifying the heat-labile toxin (LT) gene . Two synthetic primers, each of which was 20 bases in length, were used with the thermostable DNA polymerase from Thermus aquaticus to amplify the LT gene . The amplified PCR products were detected by either gel electrophoresis or hybridization to a 24-base synthetic oligonucleotide probe conjugated to alkaline phosphatase . The PCR method detected LT-positive bacteria but did not react with E . coli producing the heat-stable toxin, enteroinvasive E . coli, Salmonella typhi, Salmonella typhimurium, or Shigella dysenteriae . By the PCR method, a single bacterium could be detected following 30 cycles of amplification . The T . aquaticus DNA polymerase was inhibited by more than 10(3) organisms in the amplification reaction mixture . A group of 40 clinical specimens consisting of 16 LT bioassay-positive and 24 LT bioassay-negative stool specimens were tested by PCR for the presence of toxigenic E . coli . The total DNA from 100 microliters of stool specimen was extracted and partially purified with a commercially available ion-exchange column . All 16 of the bioassay-positive stool specimens were positive by PCR . In addition, one stool specimen which was bioassay negative for LT but positive for LT in a previous hybridization assay with a different LT probe was also positive by PCR . This may indicate that the LT gene is present but either is not expressed or is expressed below detectable levels . Amplification of specific DNA sequences by PCR provides a highly sensitive and specific tool for the detection of pathogenic microorganisms directly from clinical specimens without the need for prior isolation . This technique may find wide application in the detection of other organisms in addition to enterotoxigenic E.coli.

J Bacteriol, 1989 Feb, 171(2), 1028 - 34
Genetic characterization of frameshift suppressors with new decoding properties; Hughes D et al.; Suppressor mutants that cause ribosomes to shift reading frame at specific and new sequences are described . Suppressors for trpE91, the only known suppressible -1 frameshift mutant, have been isolated in Escherichia coli and in Salmonella typhimurium . E . coli hopR acts on trpE91 within the 9-base-pair sequence GGA GUG UGA, is dominant, and is located at min 52 on the chromosome . Its Salmonella homolog maps at an equivalent position and arises as a rarer class in that organism as compared with E . coli . The Salmonella suppressor, hopE, believed to be in a duplicate copy of the same gene, maps at min 17 . The +1 suppressor, sufT, acts at the nonmonotonous sequence CCGU, is dominant, and maps at min 59 on the Salmonella chromosome.

Carcinogenesis, 1989 Feb, 10(2), 335 - 41
Photolysis of arylazides and generation of highly electrophilic DNA-binding and mutagenic intermediates; Wild D et al.; Photolysis of arylazides with long wavelength ultraviolet (NUV) light in an aqueous medium produces short-lived reactive chemical species which bind to DNA and deoxynucleoside 3'-phosphates and induce reversion mutations in frameshift tester strains of Salmonella typhimurium . Nitrenes are known reactive products of azide photolysis, so the DNA-binding and mutagenic species is either a nitrene or a nitrene-derivative . An N-hydroxyarylamine intermediate, potentially formed from a nitrene and water, can be excluded because the mutagenic potencies of the reactive species in TA98 and in the hydroxylamine-resistant TA98/1,8-DNP6 are of the same order, and because the life-time of this species is very short . The mutagenic potency of the arylazide photolysis products decreases in the order azido-IQ greater than 1-azidopyrene greater than azido-MeIQx greater than 6-azidochrysene greater than 2-azidofluorene greater than 4-azidobiphenyl greater than 2-azido-naphthalene greater than 1-azido-naphthalene . This potency sequence correlates with that of the corresponding arylamines . Furthermore, their DNA binding products are chromatographically identical with those obtained in cellular, metabolizing systems from nitroarenes and arylamines . Therefore, the reactive, electrophilic azide photolysis product is very likely a nitrenium ion formed by protonation of a nitrene . Nitrenium ions are also the ultimate mutagens/carcinogens formed from nitroarenes and arylamines . Arylazides can therefore be considered as stabilized forms of arylnitrenium ions . The arylazide-nitrene technique reported here is new and simple and provides ready access to presumed nitrenium ions which are otherwise difficult to obtain.

Mutat Res, 1989 Feb, 210(2), 263 - 9
Mutagenicity of the phenolic microsomal metabolites of 3-nitrofluoranthene and 1-nitropyrene in strains of Salmonella typhimurium; Consolo MC et al.; The environmental pollutant 3-nitrofluoranthene is metabolized in vitro and in vivo to several products including the phenolic metabolites 3-nitrofluoranthen-6-ol (3NF-6-ol), 3-nitrofluoranthen-8-ol (3NF-8-ol), and 3-nitrofluoranthen-9-ol (3NF-9-ol) . Similarly, 1-nitropyrene is metabolized to the phenolic metabolites 1-nitropyren-3-ol (1NP-3-ol), 1-nitropyren-6-ol (1NP-6-ol), and 1-nitropyren-8-ol (1NP-8-ol) . The mutagenicity of these compounds was investigated using strains of Salmonella typhimurium deficient in either certain nitroreductases or the aryl hydroxylamine O-esterificase . In TA98, 3-nitrofluoranthene and 3NF-8-ol were equally mutagenic at approximately 10(3) revertants/nmole while 3NF-6-ol and 3NF-9-ol were 10-fold less mutagenic . 1-Nitropyrene and 1NP-3-ol likewise were equally mutagenic at approximately 700 revertants/nmole and 1NP-6-ol and 1NP-8-ol were 100-fold less mutagenic . The mutagenicity of 1-nitropyrene was dependent on the 'classical nitroreductase' which is absent in TA98NR, and that of 3-nitrofluoranthene, 3NF-8-ol, and 1NP-3-ol was less dependent on this nitroreductase . Using TA98/1,8DNP6, it was determined that the mutagenicity of 3-nitrofluoranthene, 3NF-8-ol, and 1NP-3-ol but not 1-nitropyrene was dependent on the presence of the O-esterificase . 3-Nitrofluoranthene and 3NF-8-ol were mutagenic in TA100, while 3NF-6-ol and 3NF-9-ol were considerably less mutagenic . 3-Nitrofluoranthene was not mutagenic in TA100NR nor in TA100-Tn5-1,8DNP1012 . None of the phenolic metabolites of 3-nitrofluoranthene were mutagenic in TA100-TN5-1,8DNP1012 indicating a strong dependence for mutagenicity on the O-esterificase or the 1,8-dinitropyrene nitroreductase which is absent in this strain . These results are discussed in view of possible mechanisms for the differences in the mutagenicity of the phenolic metabolites of these two nitrated arenes.

Mol Microbiol, 1989 Feb, 3(2), 177 - 86
Isolation, molecular characterization and expression of the ushB gene of Salmonella typhimurium which encodes a membrane-bound UDP-sugar hydrolase; Garrett AR et al.; The UDP-sugar hydrolase of Salmonella typhimurium has previously been reported to be located in both the inner and the outer membrane . We have cloned the gene, designated ushB, encoding this enzyme and determined its nucleotide sequence . No significant sequence homology with the periplasmic UDP-sugar hydrolase of Escherichia coli was found at either the DNA or protein level . However, a sequence is detectable, in the E . coli genome, which weakly hybridizes with a specific ushB probe . Polypeptide analysis has allowed the identification of the Salmonella hydrolase which has an Mr of 28,349 as compared to an Mr of 60,767 for the E . coli hydrolase . Most of the protein (approximately 90%) is located in the inner membrane . Two independent membrane fractionation procedures indicate that the remainder may be associated with the outer membrane . The deduced primary structure indicates the presence of an N-terminal signal peptide, although certain features of the region surrounding the putative processing site indicate that processing may be inefficient, or may not occur . Experiments with several inhibitors of signal peptidase function fail to demonstrate the appearance of a precursor form.

Microb Pathog, 1989 Feb, 6(2), 81 - 91
Modulation of resistance to Salmonella typhimurium infection in mice by mouse hepatitis virus (MHV); Fallon MT et al.; Prior infection of mice with a field strain of mouse hepatitis virus (MHV) increased the early resistance of euthymic mice to virulent Salmonella typhimurium strain SR-11 infections (as defined by significantly fewer salmonella colony-forming units (cfu) present in spleens and livers 4 days after salmonella infection) . This increase in salmonella resistance was observed when the interval between MHV and salmonella infections was 6 days, but not at 3, 10, or 14 day intervals . The mouse Ity locus, which controls the number of intracellular salmonella, had a significant effect on the ability of MHV to induce resistance to salmonella . MHV caused an increase in resistance to salmonella in Itys (salmonella susceptible) mice at all doses of salmonella tested (100 to 10,000 cfu) . In the Ityr (salmonella resistant) mice tested the beneficial effect of MHV on salmonella resistance was small and when observed, was only present at salmonella doses of 10,000 cfu or greater . Neither the Lpsd nor Xid mutations affected the ability of MHV to increase resistance to salmonella infection . In contrast to euthymic mice, MHV infection greatly decreased the resistance of athymic (nude) mice to salmonella infection . Since the Nu locus does not affect the resistance of mice to salmonella (at 4 days post salmonella infection), these results indicate that MHV infection and the nude phenotype interact to increase susceptibility to salmonella . These findings re-emphasize the importance of keeping laboratory mice used in research free of MHV and other immunomodulatory pathogens.

Microb Pathog, 1989 Feb, 6(2), 153 - 8
Localization by insertion mutagenesis of a virulence-associated region on the Salmonella typhimurium 96 kilobase pair plasmid; Rhen M et al.; The virulence-associated plasmid pEX102 of Salmonella typhimurium line TML R66 was tagged with the transposon Tn5 and the virulence of the mutants obtained was assayed in the mouse salmonellosis model . Out of 36 independent insertion mutants tested two isolates had clearly reduced virulence in (CBA x C57B1/6)F1 mice . The corresponding Tn5 elements were positioned on the restriction endonuclease map of pEX102 and found to be some 4 kilobases apart (kb) on the 96 kb virulence plasmid.

Zentralbl Veterinarmed A, 1989 Feb, 36(2), 90 - 103
Clinical, endocrinological and spermatological studies after endotoxin in the ram; Wallgren M et al.; Eight rams were injected intravenously with endotoxin from Salmonella typhimurium . Blood plasma was analysed for the contents of 15-ketodihydro-PGF2 alpha, LH, testosterone, calcium and total amount of white blood cells . Semen was examined for motility, concentration, volume and morphological appearance . After castration at 4 or 16 weeks the testes were examined histologically . The total white blood cells and the calcium levels as well as LH and testosterone decreased and the levels of 15-ketodihydro-PGF2 alpha rose after the endotoxin administration . The examination of the semen showed a significant decrease in motility and a significant increase in abnormal sperm heads . The histological examination showed a slight degeneration in the seminiferous epithelium in the rams castrated at 4 weeks after the endotoxin administration; this degeneration was not seen in the rams castrated at 16 weeks . The present results indicate that endotoxin seems to exert a negative effect on the genital functions of the ram; the changes in LH and testosterone are very similar to those seen after heat induced stress . The histological changes indicate a short-lasting mild degeneration in the seminiferous epithelium.

Jpn J Cancer Res, 1989 Feb, 80(2), 126 - 31
Changes in the quantity and activity of cytochrome P-450 isozymes in primary cultured rat hepatocytes; Namiki M et al.; Hepatocytes from male Sprague-Dawley rats pretreated with a cytochrome P-450 inducer, 3-methoxy-4-aminoazobenzene (3-MeO-AAB), 3-methylcholanthrene (MC) or phenobarbital (PB), were cultured in vitro, and changes in the quantity and activity of microsomal cytochrome P-450 isozymes in the cells were determined by means of immunochemical methods and a bacterial mutation test, respectively . The results of enzyme-linked immunosorbent assay using monoclonal antibodies against rat P-450 isozymes revealed that the amount of cytochrome P-450d induced by 3-MeO-AAB or MC declined rapidly during culture and fell to 10 to 15% of the initial value after 24 h . A similar tendency was observed with PB-induced cytochrome P-450b/e . By contrast, cytochrome P-450c in MC-induced hepatocytes declined more slowly than cytochrome P-450d and remained at 45 to 60% of the initial value after 24 h . Similar quantitative changes of the individual cytochrome P-450 isozymes in culture were also observed by immunoblotting using the anti-cytochrome P-450 monoclonal antibodies . Changes in the activities of individual cytochrome P-450 isozymes in hepatocytes by culture were in accordance with the quantitative changes of the cytochromes, as determined by a mutation test using Salmonella typhimurium TA 98 and carcinogenic aromatic amines . These results indicate that microsomal cytochrome P-450c in primary cultured rat hepatocytes is more stable in culture, in terms of both quantity and activity, than cytochrome P-450d and P-450b/e.

Zentralbl Bakteriol Mikrobiol Hyg {B}, 1989 Feb, 187(3), 230 - 43
{The mutagenicity of organic microcontamination in the environment . II . The mutagenicity of volatile organic halogens in the Salmonella microsome test (Ames Test) with regard to the contamination of groundwater and drinking water}; Mersch-Sundermann V; To determine the sensitivity and specificity of microbial shortterm-tests for the registration of the mutagenic potency of halogenated hydrocarbons (OHV) 18 pure substances out of the groups of halomethanes, -ethanes and -ethylenes were examined with different laboratory methods (classical Ames-Test, Spot-Testing, Preincubation-Procedure) of the Salmonella-Microsome-Test (Ames-Test) . The Salmonella typhimurium- strains TA97, TA98, TA100 und TA102 were used with and without metabolic activation of Arochlor 1254 induced rat-liver microsomes . Mutagenicity with one or several procedures shows 1,1,2,2-tetrachloroethane, hexachloroethane, trichloroethylene, bromdichloromethane and bromoform without metabolic activation and dichloromethane, tetrachloromethane, 1,1,2,2-tetrachloroethane, hexachloroethane, 1,1-dichloroethylene, trans-1,2-dichloroethylene, tetrachloroethylene and bromdichloromethane with metabolic activation . The range of sensitivity amounted from microgram to nanogram values of OHV's per plate, so that the Ames-test can be a sensitive screening method sufficient for detection of mutagenic effects by several OHV's in high contaminated environmental samples even without extraction procedures.

J Bacteriol, 1989 Feb, 171(2), 737 - 43
Correlation between histidine operon expression and guanosine 5'-diphosphate-3'-diphosphate levels during amino acid downshift in stringent and relaxed strains of Salmonella typhimurium; Shand RF et al.; We have analyzed the correlation of attenuator-independent expression of the Salmonella typhimurium histidine operon in vivo with levels of the "alarmone" guanosine 5'-diphosphate 3'-diphosphate . Amino acid downshift caused by serine hydroxamate addition increased his expression in a relA+ strain and decreased his expression in a relA mutant, whereas levels of guanosine 5'-diphosphate-3'-diphosphate varied in parallel with the changes in his expression in the two strains . In several experiments, overall variations in his expression ranged from 20- to 60-fold after downshift . The mild downshift allowed growth of the cultures to continue at near-preshift rates . Serine hydroxamate addition was also used to analyze the effect of amino acid downshift on induced expression of wild-type and mutant lac promoters . There was a 12-fold difference in lac expression when a relA+-relA1 pair was subjected to mild starvation but only a 3-fold difference when the strains carried the lacZpL8UV5 promoter mutation . These results suggest that guanosine 5'-diphosphate-3'-diphosphate stimulates gene expression in vivo at the level of transcription initiation.

Infect Immun, 1989 Feb, 57(2), 609 - 15
Capacity of recombinant gamma interferon to activate macrophages for Salmonella-killing activity; Kagaya K et al.; The ability of recombinant gamma interferon (rIFN-gamma) to activate macrophages for Salmonella-killing activity was kinetically examined in relation to phagosome-lysosome fusion and H2O2 generation . Resident peritoneal macrophages of BALB/c mice incubated with 10(2) to 10(3) U of rIFN-gamma per ml for 12 h exhibited enhanced bactericidal activity against Salmonella typhimurium, although H2O2 generation was unaltered . In contrast, macrophages incubated with equal doses of rIFN-gamma for 48 h showed both an enhanced Salmonella-killing activity and an increased generation of H2O2 . To evaluate Salmonella-killing activities of macrophages, intracellular bacteria were assayed at 0, 2, and 8 h after infection . During the initial 2 h of infection, 12-h-activated macrophages, as well as the unstimulated control macrophages, showed a decline in bacterial population at the same rate . Over the next 6 h of infection, however, the number of viable bacteria in activated macrophages remained unchanged, whereas the number of bacteria in control macrophages significantly (P less than 0.05) increased . Similar results were obtained in 48-h-activated macrophages . On the other hand, macrophages incubated with 10 to 10(3) U of rIFN-gamma exhibited enhanced fusion of lysosomes to Salmonella-containing phagosomes in both the 12-h- and 48-h-stimulated stages . Moreover, when 48-h-activated macrophages were incubated concomitantly with superoxide dismutase and catalase, Salmonella-killing activity was not affected . These results indicate that rIFN-gamma per se is able to activate peritoneal macrophages to induce Salmonella-killing activity and suggest that increased phagosome-lysosome fusion followed by an oxygen-independent killing mechanism is primarily responsible for the enhanced Salmonella-killing activity in rIFN-gamma-activated macrophages.

Infect Immun, 1989 Feb, 57(2), 432 - 7
Altered expression of the Salmonella typhimurium-specific B-cell repertoire in mice chronically treated with antibodies to immunoglobulin D; Fultz MJ et al.; Using a modification of the splenic focus assay, we analyzed the Salmonella typhimurium-specific B-cell repertoire in salmonella-susceptible BALB/c mice . Although these mice normally succumbed to salmonella infection before antibody was produced, they appeared to have splenic S . typhimurium-specific B-cell precursors that could be activated to differentiate and secrete antibody in a manner which was quantitatively and qualitatively identical to that of salmonella-resistant mouse strains . We also analyzed the primary S . typhimurium-specific B-cell repertoire in BALB/c mice that had been chronically treated with antibodies to immunoglobulin D (IgD) and therefore had no surface IgD-positive B cells . Although the frequency of S . typhimurium-specific precursors in these mice was similar to that of control mice, there was an apparent alteration in the isotype distribution pattern in anti-IgD-treated mice . Control mice generated a significantly greater proportion of IgG-secreting clones than did anti-IgD-treated mice . In addition, a greater proportion of S . typhimurium-specific clones from control mice secreted IgG2 than secreted IgG1, and those clones that secreted IgG2 but not IgM, IgG3, or IgG1 were greater than 20-fold more common in control than in anti-IgD-treated mice . Finally, we analyzed the immune response of control and anti-IgD-treated mice to a live avirulent vaccine, S . typhimurium SL3235 . Although both groups were protected after challenge with a live virulent S . typhimurium strain, only the control mice made serum antibodies to this vaccine . Taken together, these results show that (i) salmonella-susceptible BALB/c mice have S . typhimurium-specific B cells, (ii) the S . typhimurium-specific B cells in anti-IgD-treated mice may have a restricted capacity to switch heavy-chain classes, (iii) the similarity observed in the frequency of the S . typhimurium-specific precursors for these two groups of BALB/c mice is not reflected in the serum, and (iv) the failure of anti-IgD-treated mice to generate a serum antibody response to SL3235 in the face of complete protection suggests that this model may be used to study cell-mediated immune mechanisms in the apparent absence of humoral immunity.

J Biol Chem, 1989 Jan 25, 264(3), 1488 - 96
An alkyl hydroperoxide reductase from Salmonella typhimurium involved in the defense of DNA against oxidative damage . Purification and properties; Jacobson FS et al.; A peroxide reductase (peroxidase) which converts lipid hydroperoxides and other alkyl hydroperoxides to the corresponding alcohols, using either NADH or NADPH as the reducing agent, has been identified in both Salmonella typhimurium and Escherichia coli . This enzyme is shown to play a role in protecting against alkyl hydroperoxide mutagenesis . To our knowledge this work represents the first description of an NAD(P)H peroxidase in enteric bacteria and the first reported bacterial peroxidase to exhibit high activity toward alkyl hydroperoxides . A high performance liquid chromatography-based assay for the alkyl hydroperoxide reductase has been developed by monitoring the reduction of cumene hydroperoxide, a model alkyl hydroperoxide . By using this assay, the enzyme has been purified from a S . typhimurium regulatory mutant, oxyR1, which overexpresses a number of proteins involved in defenses against oxidative damage, and which contains 20-fold more of the alkyl hydroperoxide reductase than the wild-type strain . The purified activity requires the presence of two separable components having subunit molecular weights of 22,000 and 57,000 . The 57-kDa protein contains a bound FAD cofactor and can use either NADH or NADPH as an electron donor for the direct reduction of redox dyes, or of alkyl hydroperoxides when combined with the 22-kDa protein . This enzyme may thus serve as a prokaryotic equivalent to the glutathione reductase/glutathione peroxidase system in eukaryotes.

Biochemistry, 1989 Jan 24, 28(2), 431 - 7
Mechanism of inactivation of alanine racemase by beta, beta, beta-trifluoroalanine; Faraci WS et al.; The alanine racemases are a group of PLP-dependent bacterial enzymes that catalyze the racemization of alanine, providing D-alanine for cell wall synthesis . Inactivation of the alanine racemases from the Gram-negative organism Salmonella typhimurium and Gram-positive organism Bacillus stearothermophilus with beta, beta, beta-trifluoroalanine has been studied . The inactivation occurs with the same rate constant as that for formation of a broad 460-490-nm chromophore . Loss of two fluoride ions per mole of inactivated enzyme and retention of {1-14C}trifluoroalanine label accompany inhibition, suggesting a monofluoro enzyme adduct . Partial denaturation (1 M guanidine) leads to rapid return of the initial 420-nm chromophore, followed by a slower (t1/2 approximately 30 min-1 h) loss of the fluoride ion and 14CO2 release . At this point, reduction by NaB3H4 and tryptic digestion yield a single radiolabeled peptide . Purification and sequencing of the peptide reveals that lysine-38 is covalently attached to the PLP cofactor . A mechanism for enzyme inactivation by trifluoroalanine is proposed and contrasted with earlier results on monohaloalanines, in which nucleophilic attack of released aminoacrylate on the PLP aldimine leads to enzyme inactivation . For trifluoroalanine inactivation, nucleophilic attack of lysine-38 on the electrophilic beta-difluoro-alpha, beta-unsaturated imine provides an alternative mode of inhibition for these enzymes.

J Mol Biol, 1989 Jan 20, 205(2), 461 - 3
D-alanine-D-alanine ligase (ADP) from Salmonella typhimurium . Overproduction, purification, crystallization and preliminary X-ray analysis; Knox JR et al.; The ddlA gene from Salmonella typhimurium coding for D-alanine-D-alanine ligase (ADP-forming) has been subcloned behind the tac promotor in the plasmid pKK223-3, with expression in Escherichia coli JM105 . The overexpression system yields 58 mg of active enzyme from 12 g of wet cell paste after 40-fold purification to homogeneity . 5,5'-Dithiobis-(2-nitrobenzoic acid) titrations indicate that all four cysteine residues exist as free thiols . Two crystal forms of the 39,300 Mr enzyme have been produced . A tetragonal form grows at 21 degrees C from 10 to 15% (w/v) polyethylene glycol 8000 in space group P4(1)2(1)2, with two molecules in the asymmetric unit; it has cell constants a = b = 83.8 A, c = 220.0 A, and diffracts to 2.9 A . A monoclinic form grows from 30% (w/v) ammonium sulfate in space group P2(1), with two molecules in the asymmetric unit; it has cell constants a = 60.4 A, b = 102.1 A, c = 64.3 A, beta = 115.7 degrees, and diffracts to 2.2 A resolution.

J Immunol, 1989 Jan 15, 142(2), 381 - 7
Late events in B cell activation . Expression of membrane alkaline phosphatase activity; Burg DL et al.; Alkaline phosphatase (APase) has been previously described as a membrane marker correlating with B cell proliferation after stimulation by selected B cell mitogens . We have found, however, that the appearance of B cell membrane APase correlates more closely with differentiation than with proliferation . This conclusion has been drawn from the following observations: 1) APase activity appears well after peak B cell thymidine uptake, 2) mitogens which stimulate only B cell proliferation (Salmonella typhimurium mitogen) fail to induce expression of the enzyme, and 3) when proliferation of mitogen-activated B cells is inhibited, APase activity is not suppressed and may even be augmented . In addition to membrane expression, APase is also spontaneously shed into the surrounding milieu, perhaps as a result of endogenous phospholipase activity . By using a group of well-characterized inhibitors, the APase activity was shown to belong to class I (similar to the bone/liver/kidney class) . Because APase always appears in differentiating but not proliferating cells, we would propose that the enzyme appearance is a late marker of B cell activation, associated with cell progression to differentiation and consequent IgM synthesis.

J Biol Chem, 1989 Jan 15, 264(2), 1224 - 31
Overlapping transcription and termination of the convergent ilvA and ilvY genes of Escherichia coli; Sameshima JH et al.; The ilvY gene of Escherichia coli is transcribed in a direction opposite to the ilvGMEDA operon, and the translational stop codons of the ilvA and ilvY genes are only 52 base pairs (bp) apart . We have employed galK transcriptional analyses, in vitro transcription assays, and S1 nuclease mapping to show that the converging transcripts of the ilvGMEDA operon and the ilvY gene overlap . The ilvGMEDA transcript terminates at two sites in the distal amino acid coding region of the ilvY gene: a rho-independent termination site 116 bp downstream of the ilvA translational stop codon, ilvA t, and a 62-bp-long rho-dependent termination site, ilvA t', beginning 70 bp beyond the ilvA t site . This tt' termination pattern at the distal end of the ilvGMEDA operon is similar to that of the trp operon of E . coli and the leu operon of Salmonella typhimurium . Termination of ilvY transcription occurs over a broad stretch of DNA several hundred base pairs downstream of the ilvY translational stop codon in the middle of the amino acid coding region of the ilvA gene . These experiments demonstrate that the converging transcripts from the ilvA and ilvY genes terminate in the coding region of the opposing gene.

BMJ, 1989 Jan 14, 298(6666), 99 - 101
Large outbreak of food poisoning caused by Salmonella typhimurium definitive type 49 in mayonnaise; Mitchell E et al.; An investigation was conducted to determine the vehicle of infection of an outbreak of food poisoning in a large metropolitan building early in 1988 . A questionnaire was distributed to 700 people who had eaten in the building during the week of the outbreak, and attack rates for specific food were calculated . Food and stool samples, environmental samples, and eggs and environmental swabs from the egg suppliers were examined microbiologically . Altogether 474 questionnaires were returned, 120 people reporting gastrointestinal illness . The illness was significantly associated with foods containing mayonnaise . Salmonella typhimurium definitive type 49 was isolated from 76 of the 84 stool samples containing salmonella and from five of the eight samples taken from the chicken house of the main egg supplier . Mayonnaise was probably the vehicle of infection, which was caused by S typhimurium definitive type 49.

Cancer Res, 1989 Jan 1, 49(1), 20 - 4
Mutagenicity and tumorigenicity of dihydrodiols, diol epoxides, and other derivatives of benzo(f)quinoline and benzo(h)quinoline; Kumar S et al.; The mutagenic activities of benzo{f}quinoline, benzo{h}quinoline, and a number of their derivatives, including dihydrodiols, K-region oxides, diol epoxides, and tetrahydroepoxides, were assessed in strain TA 100 of Salmonella typhimurium . The dihydrodiol derivatives of benzo{f}quinoline and benzo{h}quinoline were also tested for tumorigenic activity in newborn mice . Benzo{f}quinoline was metabolically activated in the presence of rat liver S-9 preparation to products mutagenic to the bacterial system to a greater extent than was benzo{h}quinoline . However, trans-7,8-dihydro-7,8-dihydroxybenzo{f}quinoline was less mutagenic compared to trans-7,8-dihydroxy-7,8-dihydrobenzo{h}quinoline in the presence of rat liver homogenate . The data on the mutagenic activity of the dihydrodiol derivatives of benzoquinolines were consistent with the intrinsic mutagenicity of the corresponding epoxide derivatives, in that the bay-region diol epoxides and tetrahydroepoxide of benzo{h}quinoline exhibited considerably higher mutagenic activities compared to those of the corresponding derivatives of benzo{f}quinoline at equivalent doses . The K-region oxides of benzo{f}quinoline and benzo{h}quinoline were significantly less mutagenic than their corresponding bay-region diol epoxide and tetrahydroepoxide derivatives . The demonstration that benzo{f}quinoline is significantly more mutagenic than trans-7,8-dihydro-7,8-dihydroxybenzo{f}quinoline, a precursor to the weakly mutagenic bay-region diol epoxide, suggests that the bay-region diol epoxide formation is not the principal pathway for the metabolic activation of benzo{f}quinoline to a mutagen . On the other hand, the isomeric benzo{h}quinoline appears to exert its mutagenic effect via the formation of its bay-region diol epoxide . These results indicate that the position of a nitrogen heteroatom in phenanthrene (the analogous carbocyclic aromatic hydrocarbon) not only has a marked effect on the mutagenic activities of the diol epoxide derivatives, but also can alter the metabolic activation pathways of the parent hydrocarbon . Benzo{f}quinoline, benzo{h}quinoline, and their dihydrodiol derivatives were not tumorigenic in newborn mice.

Vopr Onkol, 1989, 35(7), 837 - 42
{Identification of trihalomethanes in drinking water and assessment of their toxicity, mutagenicity and carcinogenicity}; Khudolei VV et al.; Dichlorobromomethane (DCMB) and dibromochloromethane (DBCM) isolated from chlorinated drinking water were tested for toxicity, mutagenicity and carcinogenicity . Both agents proved mutagenic in a "dessicator" modification of the Ames test using Salmonella typhimurium TA98 and TA100 in the presence of exogenous metabolic activation . In aquarium Danio rerio fish tests, LD50/30 was 250 mg/l for both compounds . Both agents induced hepatocellular carcinoma in fish: DCMB--in 11 out of 29 animals (at 16.5 weeks) and DBCM--in 3 out of 16 (at 26.5 weeks) . These data merit further investigation of the agents' carcinogenicity in chronic experiments in rodents.

Dermatol Monatsschr, 1989, 175(5), 261 - 7
{The cytotoxic and antimutagenic effect of dithranol}; Bernd A et al.; The anti-psoriatic compound anthralin (dithranol, cignolin) was determined to exhibit a strong cytostatic activity on HeLa-Koln cells; an ED50 concentration of 1.2 microM was determined for the cells . These growth-inhibition data were confirmed by thymidine-uptake experiments . The drug anthralin was determined to be neither direct a mutagen nor a premutagen in the Ames test using Salmonella typhimurium strain TA 100 (anthralin-concentration = 5 microM) . Moreover, this compound was a strong inhibitor of benzo(a)pyrene monooxygenase, an enzyme which causes the metabolic conversion of premutagens to mutagens . These data demonstrate anthralin to be an antipsoriatic compound devoid of mutagenic property in vitro with regard to base-pair substitutions and provided at least with some antimutagenic potential.

J Bacteriol, 1989 Jan, 171(1), 130 - 40
Molecular characterization of the cysJIH promoters of Salmonella typhimurium and Escherichia coli: regulation by cysB protein and N-acetyl-L-serine; Ostrowski J et al.; The cysJIH promoter regions from Salmonella typhimurium LT7 and Escherichia coli B were cloned and sequenced . Primer extension analyses showed that the major in vivo transcription initiation site in S . typhimurium is located 171 nucleotides upstream of the cysJ start codon . Minor start sites were found 8 and 9 nucleotides downstream of the major site . In vivo transcription initiation in E . coli was found to occur at a single site 66 nucleotides upstream of the cysJ start codon . Primer extension studies also indicated that chromosomal cysJIH transcription is stimulated by sulfur limitation and repressed by growth on L-cystine . Paradoxically, in strains carrying plasmids containing the S . typhimurium cysJIH region, the highest levels of primer extension products were found with RNA from cells grown on L-cystine, even though levels of the proteins encoded by cysJ and cysI were normally repressed . In vitro transcription runoff studies with DNA template from the S . typhimurium cysJIH promoter region showed synthesis of a product originating at the major in vivo start site, which was dependent on the presence of purified cysB protein and either O-acetyl-L-serine or N-acetyl-L-serine . N-Acetyl-L-serine was 10- to 30-fold more active than O-acetyl-L-serine as an in vitro inducer of cysJIH transcription.

Braz J Med Biol Res, 1989, 22(11), 1389 - 92
Intragastric infection of germfree and conventional mice with Salmonella typhimurium; Nardi RM et al.; The present study investigates the lethality of intragastric Salmonella typhimurium infection of germfree (GF) and conventional (CV, not germfree) mice . The introduction of only 10 viable S . typhimurium into the gastrointestinal tract of GF mice resulted in death of all animals within 8 days of inoculation . In contrast, the 50% lethal dose for CV mice was 4.7 x 10(3) viable organisms . The results demonstrate that resident microbes protect mice from the pathogenic effect of S . typhimurium infection.

Eisei Shikenjo Hokoku, 1989, (107), 83 - 7
{Mutagenicity of steviol: an analytical approach using the Southern blotting system}; Matsui M et al.; Steviol is the aglycone of stevioside, which is a non-caloric sugar substitute commonly used in Japan . Our previous studies and Pezzuto et al . have demonstrated that steviol is mutagenic after metabolic activation in the forward mutation assay using Salmonella typhimurium TM677 (TM677), whereas it is non-mutagenic in the reverse mutation assay (Ames test) using S . typhimurium TA 100, TA98, TA102 and TA97 . There is the possibility, therefore, that activated steviol selectively induces a deletion or insertion of more than one base pair which cannot be detected by strains commonly used in the Ames test . In this study, we confirmed first that the 8-azaguanine (8-AG) resistance of the TM677 mutants appears to reside in the chromosomal gpt gene, since it can be complemented by the gpt gene of E . coli (Ecogpt) . The chromosomal DNA of TM677 and TM677 mutants were digested by several restriction enzymes: BamHI, Sau3AI, AluI, TaqI, HaeIII, HpaII and RsaI, and analyzed by the Southern blot hybridization technique with a probe to the gpt gene DNA of E . coli . No significant differences in DNA fragment length, however, were formed between the wild type and spontaneous or steviol-induced mutants.

Acta Vet Scand, 1989, 30(3), 295 - 300
The influence of flunixin on the response to Salmonella typhimurium endotoxin in calves; Luthman J et al.; The effects of intravenous injection of 0.5 microgram/kg body weight of Salmonella typhimurium endotoxin were studied in calves . The injection was followed by ruminal stasis and general dullness . The clinical signs disappeared within 24 hours . The injection was followed by a tremendous increase in the plasma level of 15-ketodihydro-PGF2 alpha, the main metabolite of PGF2 alpha . The injection was also associated with a profound leukopenia and significant decreases in the serum levels of iron, zinc and calcium . In order to study the role of prostaglandin (PG) for the development of endotoxin-induced changes a group of calves was pretreated with flunixin, a potent cyclo-oxygenase inhibitor, at a dose of 2.2 mg/kg body weight . Flunixin inhibited the PG release completely, but did not influence the other responses to endotoxin . The pyrogenic response to endotoxin was very moderate and it was suggested that fever is not the most suitable parameter for monitoring endotoxin effects in calves . The studied blood parameters (15-ketodihydro-PGF2 alpha, iron, zinc, calcium and the number of leukocytes) appeared to be much more sensitive.

Acta Vet Hung, 1989, 37(3), 219 - 26
Immunization of calves with live and inactivated whole-cell vaccines against Salmonella typhimurium infection; Mikula I et al.; Eight calves were immunized with live auxotrophic Salmonella typhimurium mutants (aro -SL 1479, gal E 3821) and twelve calves with phenol-killed whole-cell S . typhimurium vaccine, respectively . The clinical status of the animals was followed and serial reisolation of vaccine and challenge strains from faeces was attempted . The immunization of calves with the live aro- auxotrophic S . typhimurium SL 1479 mutant proved to be unsuitable due to the death of calves after revaccination . The calves immunized with live auxotrophic gal E S . typhimurium CCM 3821 mutant proved to be protected against challenge with virulent S . typhimurium 4/5 strain administered orally at a dose of 10(6) colony forming units (CFU) . The postvaccination complications showed serious shortcomings . The immunization of calves with three doses of whole-cell inactivated vaccine containing 5 strains of S . typhimurium was effective against oral challenge with virulent S . typhimurium 4/5 at a dose of 10(6) CFU.

Mol Toxicol, 1989 Winter, 2(1), 53 - 65
Aromatic amines and acetamides in Salmonella typhimurium TA98 and TA100: a quantitative structure-activity relation study; Trieff NM et al.; The mutagenicity of a series of 19 aromatic amines had been previously measured in Salmonella typhimurium strains TA98 (frame-shift) and TA100 (base-pair) with the addition of S9 from Aroclor 1254-induced rat liver . A quantitative structure-activity relation (QSAR) study using multiple regression analysis points out the influence of three factors on mutagenicity: lipophilic character, position of the amine group, and whether it is free or acetylated, as expressed by log P and two indicator variables I1 and I2, respectively . The multiple regression equations explain 78 and 88% of the variance in log mutagenicity in TA98 and TA100, respectively . First of all, mutagenicity was shown to increase with lipophilicity . On the other hand, mutagenicity is reduced when the amine or acetamido position is ortho to the juncture because of steric hindrance in its biotransformation compared with a non-ortho isomer . It is decreased also by the acetylation of the amine group, probably because the acetyl group needs to be first split off prior to oxidation of the amine group to -NHOH.

Arch Microbiol, 1989, 153(1), 19 - 25
UTP/CTP ratio, an important regulatory parameter for ATCase expression; O'Donovan GA et al.; Intracellular nucleotides of Salmonella typhimurium were separated and quantified by high performance liquid chromatography (HPLC) . Wild type and specially constructed strains of S . typhimurium, in which uridine and cytidine nucleotides could be manipulated independently, were used in this study . By varying growth conditions it was possible to create different concentrations of uridine and cytidine nucleotides in the cell . The specific activity of ATCase was determined for each condition . Generally, a direct correlation was found: at high nucleotide (UTP) concentrations, maximal repression of ATCase was usually seen; at low nucleotide (UTP) concentrations ATCase was derepressed . However, it was the ratio of the concentrations of UTP-to-CTP rather than either the concentration of UTP or CTP alone that best determined the extent of ATCase expression . This applied to all conditions in the present work as well as to all conditions in work hitherto reported by others . The ratio of UTP/CTP is proposed as a key regulatory parameter for pyr enzyme expression.

Environ Mol Mutagen, 1989, 14(3), 146 - 8
Crotonaldehyde is mutagenic in Salmonella typhimurium TA100; Neudecker T et al.; The mutagenicity of crotonaldehyde in Salmonella typhimurium TA100 cannot be demonstrated in the standard plate incorporation assay . However, as reported earlier by our group, this alpha, beta-unsaturated aldehyde is clearly mutagenic in the liquid assay modification of this testing procedure . Carried out because of the doubts recently expressed by Cooper et al . (Environ Mutagen 9:289-295, 1987) concerning the observed mutagenicity of crotonaldehyde in S . typhimurium TA100, this study confirms that this compound is clearly a direct (without activation by mammalian microsomes)-acting mutagen in S . typhimurium TA100 under appropriate conditions in the preincubation assay . The observed mutagenicity is increased by extended preincubation time and increased bacterial cell densities.

Drugs Exp Clin Res, 1989, 15(4), 145 - 50
Characterization of a plasmid coding for resistance to broad-spectrum cephalosporins in Salmonella typhimurium; Garbarg-Chenon A et al.; Five strains of Salmonella typhimurium isolated from faeces of infants hospitalized at Trousseau Hospital in Paris have been found to be resistant to third-generation cephalosporins . This resistance is by a transferable plasmid-mediated mechanism . The beta-lactamase gene which encodes for an enzyme similar to SHV-2 has been cloned into plasmid pBR322 and expressed in Escherichia coli RR1.

Zentralbl Mikrobiol, 1989, 144(3), 197 - 202
Mutagenicity assay with Salmonella typhimurium revealing biotransformation of antiphytoviral substances by cell-free plant extract; el-Tarras A et al.; The mutagenic activity of four antiphytoviral substances was tested in reversion mutagenicity assays with a set of histidine auxotrophic strains of Salmonella typhimurium by means of the preincubation method . A possible metabolic activation of the substances by cell free fractions from maize seedlings (S-14-fraction) and for comparison from mouse liver (S-9 mix) was examined . None of the guanidine, phenyl urea and thiadiazole compounds exerted mutagenic activity in the bacterial strains in experiments without metabolic activation . Cyanoguanidine and N-phenyl-N-carboxyphenylurea became mutagenic for Salmonella strain TA98 after metabolic activation by the S-14 plant fraction . Both substances were not mutagenic in the presence of S-9 mix made from mouse liver . The promutagen cyclophosphamide proved highly mutagenic in experiments with S-14 mediated plant metabolic activation . This kind of bacterial mutagenicity assay is valuable in investigations of potential agrochemicals, as the examples have shown.

Zentralbl Mikrobiol, 1989, 144(3), 191 - 6
Mutagenicity of antiviral substances of nucleobase analogue type in Salmonella typhimurium employing metabolic activation by mouse liver homogenate or cell-free plant extracts; el-Tarras A et al.; Five nucleobase analogues with antiviral properties were tested for their mutagenic activity in his mutant strains TA 1535, TA 1537, TA 1538, TA98, and TA 100 of S . typhimurium by means of preincubation tests with and without metabolic activation by cell free fractions from mouse liver (S-9) and maize seedlings (S-14) . In one bacterial strain 6-azathymine increased the revertant counts in the absence of metabolic activation systems . In the presence of S-9 mix, the same substance became mutagenic for another tester strain . Metabolic activation by S-14 resulted in weak mutagenicity of 5-azadihydrouracil in high concentrations . 6-Azauracil, 5-azauracil, and 5-azadihydro-1,3-diacetyluracil were without mutagenic activity in all Salmonella-strains used . Cyclophosphamide, like other standard promutagens, was shown to become mutagenic in the presence of S-14 plant fraction . Thus S-14 activation system besides the S-9 liver system can be employed in mutagenicity testing with microbial systems.

Blood Cells, 1989, 15(2), 371 - 85
Lactoferrin stimulates colony stimulating factor production in vitro and in vivo; Sawatzki G et al.; A physiologic role for lactoferrin (Lf) has been implicated by (1) its antibacterial effect and (2) its involvement as a negative-feedback regulator for colony stimulating factor (CSF) and, therefore, granulocyte production . The isolation and purification of endotoxin-free, species-specific mouse and human Lf have enabled a study of the role of Lf both in vitro and in vivo . Injection of Salmonella typhimurium or LPS into mice resulted in a dose-dependent increase in plasma Lf . Treating normal and neutropenic mice with LPS showed that the plasma Lf level was directly related to the number of granulocytes found in the peripheral blood . The effect of neutropenia did not inhibit release of Lf . By incubating mouse bone marrow and adherent peritoneal cells with 0.1 microM mouse or human Lf in the absence or presence of the prostaglandin synthesis inhibitor, indomethacin (1.0 microM), no evidence could be obtained in support of a negative-feedback regulation of CSF . In fact, rather than an inhibition of CSF, the production of the latter was found to be stimulated from both cell types . Injection of endotoxin-free, mouse Lf (2 mg/animal) into mice at concentrations in the same order of magnitude as that found during bacterial infection, resulted in an increase in CSF production by 12 hours and prior to the increase in bone marrow granulocyte-macrophage progenitor cells (GM-CFC) at 48 hours . The results do not support a negative-feedback regulation of CSF by macrophages . Instead, they can be incorporated into a "demand signal" model for CSF production by macrophages.

Xenobiotica, 1989 Jan, 19(1), 43 - 50
Host-mediated bacterial mutagenesis and enterohepatic circulation of benzidine-derived mutagenic metabolites in rodents; Chipman JK et al.; 1 . Administration of benzidine (100 mg/kg, i.p.) to bile duct-cannulated rats led to a sustained excretion of metabolites in bile which, following glucuronide hydrolysis, were mutagenic to Salmonella typhimurium strain TA98 . 2 . When the biliary metabolites were re-infused into the duodena of a further group of rats, enterohepatic circulation of mutagens was indicated by extensive re-excretion of biliary mutagens in the recipients . 3 . Furthermore, in mouse host-mediated mutagenicity assays, both i.p . injection of benzidine (100 mg/kg) and intracaecal administration of rat biliary metabolites of benzidine produced a mutagenic response in Salmonella typhimurium strain TA98 cells isolated from the liver . 4 . The results indicate that enterohepatic circulation adds to the biological persistence of reactive metabolites of benzidine and may contribute to the carcinogenicity of this aromatic amine.

Med Pr, 1989, 40(1), 28 - 37
{Methods used in evaluating mutagenic and genotoxic properties of chemical compounds . II . The Ames test (an abridged version)}; Janik-Spiechowicz E; The paper presents in vitro the technique developed by Ames et al (1.5), applied in screening tests for evaluations of mutagenic effects of chemical substances . As the experimental model in the test use histidine-dependent bacterial cells of Salmonella typhimurium series TA strains . Chemical substances biotransformation is carried out in the presence of microsomal activating system (fraction S9), mostly obtained from rat's liver . Mutagenic activity of chemical substances is measured by an induction of his- mutation reversion in S . typhimurium strains, expressed as number His+ of revertant colonies, as compared to number His+ of spontaneous revertant colonies of a given strain on Petri dishes containing minimal glucose agar after 48-72 hr incubation at 37 degrees C.

Environ Mol Mutagen, 1989, 13(4), 357 - 65
Studies on the antimutagenic activities of garlic extract; Knasmuller S et al.; Experiments with Salmonella tester strains indicated that aqueous garlic extract possesses antimutagenic properties toward ionizing radiation, peroxides, adriamycin, and N-methyl-N'-nitro-nitrosoguanidine . The assumption that radical scavenging garlic constituents, i.e., molecules with sulfur moieties, might be responsible for the inhibitory effect of aqueous extract toward mutagenesis induced by radiation and radiomimetic compounds was confirmed by the results of subsequent experiments; 1) garlic extract attenuated the lethal effects of gamma-rays on repair-deficient E . coli strains; 2) the garlic constituent allicin (thio-2-propene-1-sulfinic acid S-allyl ester) is partly responsible for the reduced radiation-induced mutagenesis in Salmonella typhimurium TA 102 . No such inhibitory effects were detected with alliin (S-allyl-L-cysteine sulfoxide) or cysteine; 3) aqueous garlic extract inhibited hydrogen-peroxide-induced lipid peroxidation . Results obtained in preliminary experiments with Chinese hamster ovary cells suggest that the antimutagenic properties of garlic extract are not restricted to procaryotic cells.

Immunol Invest, 1989 Jan-May, 18(1-4), 583 - 96
Recombinant avirulent Salmonella vaccine strains with stable maintenance and high level expression of cloned genes in vivo; Curtiss R 3rd et al.; Salmonella typhimurium strains with deletion (delta) of the adenylate cyclase (cya) and cyclic AMP receptor protein (crp) genes are avirulent for mice and induce a high level of protective immunity to oral challenge with up to 10,000 times what would be a lethal dose of wild-type virulent S . typhimurium cells . This immunity begins as early as seven days after immunization and lasts for at least four months . S . typhimurium delta cya delta crp mutants stably maintain plasmids and give high-level expression of cloned gene products; in this they appear superior to other avirulent S . typhimurium strains . S . typhimurium delta cya delta crp strains with a delta asd mutation (abolishing production of aspartate beta-semialdehyde dehydrogenase), have an obligate requirement for diaminopimelic acid (DAP) . This strain can be used in conjunction with plasmid vectors lacking antibiotic resistance markers but having the wild-type asd+ gene from Streptococcus mutans to complement the delta asd chromosomal mutation . The Asd+ plasmid vector can be used to express a diversity of colonization and virulence antigens from other pathogens . In the delta cya delta crp delta asd S . typhimurium vaccine strain, the plasmid is completely stable in the absence of any exogenous selective pressure either in vitro or in vivo.

Environ Mol Mutagen, 1989, 14 Suppl 16, 39 - 45
Early years of the Salmonella mutagen tester strains: lessons from hycanthone; Hartman PE; The 1960s witnessed detailed studies on the genetic properties of a large number of histidine-requiring mutants of Salmonella typhimurium . The early 1970s saw development of selected strains, the Ames strains, for use in rapid, cheap, sensitive, and manipulable tests of chemicals and chemical mixtures for genotoxic activities . Our contribution during this latter period was an investigation into the mutagenicity of hycanthone and some of its analogues . Some lessons that this study provided are enumerated . Hycanthone is definitely a liver carcinogen in rodents predisposed by hepatic hyperplasia . Between 1969 and 1975, an estimated total of 100 kg of hycanthone was injected into some 1,000,000 humans with liver hyperplasia caused by infections with parasites . It may now be possible to assess directly the long-term impacts of hycanthone in man.

Environ Mol Mutagen, 1989, 14 Suppl 16, 35 - 8
Development of bacterial mutagenicity tests: a view from afar; MacPhee DG; A brief (and subjective) history of the progressive development of bacterial mutagenicity assays with Salmonella typhimurium and Escherichia coli is presented, with emphasis on the need to view such assays as being capable of detecting genetically active substances rather than being dedicated to the detection of carcinogenic chemicals . The role of mutation-enhancing plasmids in the improvement of Salmonella tester strains and the need for batteries of tests to allow the detection of genetic endpoints that cannot be detected with bacteria (e.g., aneuploidy) are also discussed.

Proc Natl Sci Counc Repub China B, 1989 Jan, 13(1), 56 - 63
Mutagenicity of dipyridyls and their methylated derivatives in Salmonella typhimurium/rat liver microsome system; Lin JK et al.; The Salmonella/microsome assay with strains TA97, TA98, TA100, TA1535, TA1537 and TA1538 was used to examine the potential mutagenicity of 5 dipyridyls, 1 tripyridyl, 3 dipyridinium diiodides and 2 pyridinium monoiodides . The widely used herbicide paraquat (1,1-dimethyl-4,4'-dipyridinium diiodide) and its precursor 4,4'-dipyridyl gave weak and marginal mutagenic activity to Salmonella typhimurium TA1535 and TA1538 in the presence of S9-mix . Significantly high mutagenicity was obtained with 2,2'-, 3,3'-, 2,3'-, and 2,4'-dipyridyls, 2,2',2"-tripyridyl, and 5 pyridinium salts under the same conditions . The positive mutagenic response of 2,2',2"-tripyridyl suggests that higher polymers of pyridine contaminating paraquat preparations might be mutagenic . The dose-response curves of 1,1-dimethyl-3,3'-dipyridinium diiodide and 1,1'-dimethyl-2,2'-dipyridinium diiodide revealed an exponential relationship between the number of induced revertants and the compound concentrations . The results suggested that the mechanism of mutation induced by these two compounds might be attributed to the chain reactions of their free-radicals with molecular oxygen.

Microbiologica, 1989 Jan, 12(1), 43 - 7
An enteric infection by Salmonella typhimurium: a multiple typing study; Nastasi A et al.; A multiple typing analysis was carried out on 14 apparently heterogeneous Salmonella typhimurium strains recovered during a 3 week period from an enteritis case . Conjugational transfer of resistance determinants and restriction endonuclease fingerprinting of plasmids allowed the different isolates of S . typhimurium to be attributed to a single clone.

Mutagenesis, 1989 Jan, 4(1), 45 - 50
Mutagenicity testing of rutacridone epoxide and rutacridone, alkaloids in Ruta graveolens L., using the Salmonella/microsome assay; Paulini H et al.; The mutagenicity of rutacridone and rutacridone epoxide was investigated using Salmonella typhimurium without as well as with different metabolic activation systems . Rutacridone epoxide was found to be a direct acting mutagen in S . typhimurium strains TA98, TA100 and TA1538; addition of rat liver preparations resulted in a marked decrease of mutagenicity . In contrast, rutacridone required metabolic conversion to exhibit mutagenic activity . Neither of the compounds had any effect on tester strain TA1978 . S9 mixes as well as microsomal and cytosolic preparations from untreated, phenobarbital-treated and 3-methylcholanthrene-treated rats were used to study the activation and deactivation capacities of the enzyme mixtures . In addition, the influence of enzyme inhibitors on the activation and deactivation of the furoacridones were tested . Evidence is presented that rutacridone is metabolized by rat liver enzymes to the corresponding epoxide as the ultimate mutagen.

Environ Mol Mutagen, 1989, 13(3), 263 - 70
Genotoxicity of azidoalanine in mammalian cells; Arenaz P et al.; Sodium azide mutagenesis is mediated through a metabolic intermediate in bacteria and plant species . However, very little is known about the interaction of this intermediate with nucleic acids, its genotoxic potential, or its mechanism of action, especially in mammalian cells . Chinese hamster cells and normal human skin fibroblasts were treated with extracts from Salmonella typhimurium or Hordeum vulgare (barley) containing a crude mutagenic metabolite, as well as with synthetically produced azidoalanine . The cells were evaluated for the induction of sister chromatid exchanges and the ability to perform unscheduled DNA synthesis . With the purified azidoalanine and the azide-treated extracts from Hordeum vulgare, there was a statistically significant increase in the frequency of sister chromatid exchanges observed in both Chinese hamster cells and human fibroblasts . This increase was about twofold, as compared with the control . On the other hand, there was no detectable genotoxic response when cells were exposed to azide-treated extract from Salmonella typhimurium . The results imply that azidoalanine and the crude mutagenic metabolite from Hordeum vulgare are weakly genotoxic in mammalian cells.

Environ Mol Mutagen, 1989, 13(3), 203 - 10
Role of nitroreduction in the synergistic mutational response induced by mixtures of 1- and 3-nitrobenzo{a}pyrene in Salmonella typhimurium; Thornton-Manning JR et al.; Previous studies showed that binary mixtures of the environmental pollutants 1- and 3-nitrobenzo{a}pyrene produced a synergistic mutational response in the Salmonella reversion assay . Since nitroreduction is believed to mediate the direct-acting mutagenicity of the individual compounds, we have examined the role of nitroreduction in the mutagenicity of mixtures of 1- and 3-nitrobenzo{a}pyrene in the Salmonella plate incorporation assay . While mixtures of 1- and 3-nitrobenzo{a}pyrene induced up to 183% more revertants in strain TA98 than produced by equivalent amounts of the individual compounds, in the nitroreductase-deficient strain TA98NR the same mixtures only induced up to 57% more revertants than the individual compounds . Analysis of mixtures of 1- and 3-nitrosobenzo{a}pyrene (the two-electron reduction products of 1- and 3-nitrobenzo{a}pyrene) for mutation induction in TA98 yielded no evidence of a synergistic effect between the compounds . The mutagenicity of the mixtures was dependent upon the amount of the more mutagenic component . Salmonella cultures were also incubated with mixtures of 1- and 3-nitrobenzo{a}pyrene, as well as with equivalent amounts of the individual compounds . In two experiments, nitroreductive ability, as measured by the amount of 1-nitropyrene metabolized to 1-aminopyrene in 1 hr, was increased 9 to 105% in cultures pretreated with the mixtures as compared with cultures pretreated with the individual compounds . The results of this study support the hypothesis that nitroreduction is a major factor in the synergistic mutational response induced by 1- and 3-nitrobenzo{a}pyrene in Salmonella typhimurium.

Environ Mol Mutagen, 1989, 13(3), 197 - 202
Conditions affecting the mutagenicity of trichloroethylene in Salmonella; McGregor DB et al.; Trichloroethylene (TCE) is a high production volume chemical frequently stabilized with oxiranes . These oxiranes may be responsible for the mutagenic activity of TCE in Salmonella, which has been occasionally, but not consistently, reported . High purity and oxirane-stabilized TCE samples were tested for their mutagenic potential in Salmonella typhimurium strains TA 1535, TA 98, and TA 100 . Stabilized TCE was tested using a preincubation protocol up to a dose level of 10,000 micrograms per plate, but no mutagenic response was observed in either the presence or absence of a supplementary metabolic activation system (S9 mix) derived from Aroclor 1254-induced male rat liver . TCE without oxirane stabilizers also was nonmutagenic when tested in a vapor delivery system at nominal concentrations of up to 20% and using S9 mix derived from either rat or hamster . TCE containing 0.5-0.6% 1,2-epoxybutane did induce mutagenic responses from strains TA 1535 and TA 100 in the presence and absence of S9 mix . The lowest effective dose was about 0.63% in TA 1535 in the absence of S9 mix . Vapor-phase tests with 1,2-epoxybutane showed that an atmospheric concentration of 0.009% could induce 12-fold and 3-fold increases, respectively, in strains TA 1535 and TA 100 . These increases would account for the mutagenic activity of the stabilized TCE sample . Epichlorohydrin (another commonly used stabilizer) induced similar increases in mutant numbers at an atmospheric concentration of 0.0009% . The absence of a significant response caused by unstabilized TCE in the presence of S9 mix is probably due to a lack of assay sensitivity, since chloral, a metabolite of TCE, is a mutagen in TA 100 {Haworth et al.: Environ Mutagen {Supplement 1} 5:3-142, 1983}.

Acta Otolaryngol Suppl, 1989, 457, 100 - 15
Endotoxin permeability through the round window; Kawauchi H et al.; The permeability of the round window membrane to Salmonella typhimurium derived endotoxin was examined using a total of 17 chinchillas . One mg of endotoxin was instilled into the tympanic cavity via the superior bulla . Endotoxin activity in middle ear effusions (MEEs), perilymph (both inoculated and non-inoculated side), and sera was determined by Limulus lysate assay after 12, 24, 48, 72, and 120 h following endotoxin instillation . Endotoxin was detected in perilymph on the inoculated side by 12 h after endotoxin instillation and persisted for 5 days during the present measurement period . Endotoxin level peaked at 24-48 h post-instillation, and steadily declined afterwards . This result suggests that the maximum penetration occurred during the active inflammatory stage . Histologic investigation revealed marked pathological changes in the inner ear, including bleeding and inflammatory cell recruitment, mostly in the perilymphatic spaces (e.g . scalae tympani and vestibuli, spiral ligament), strial swelling, and sensory cell degeneration . These results suggest that endotoxin, when introduced into the middle ear, can permeate through the round window membrane and can cause inner ear tissue damage in this animal model.

J Pineal Res, 1989, 6(1), 73 - 6
A study of the mutagenicity of melatonin and 6-hydroxymelatonin; Neville S et al.; The mutagenicity of melatonin and its major metabolite 6-hydroxymelatonin were evaluated using the Ames test and three strains of Salmonella typhimurium--TA 97, TA 98, and TA 100 . Neither compound exhibited mutagenicity whether in the presence or absence of an activation system derived from rats induced with Aroclor 1254 . Positive controls were employed throughout and gave the expected response . We conclude that melatonin, 6-hydroxymelatonin, and their microsomal metabolites are not mutagenic in the Ames test.

Am J Vet Res, 1989 Jan, 50(1), 22 - 8
Comparative effects of cholera toxin, Salmonella typhimurium culture lysate, and viable Salmonella typhimurium in isolated colon segments in ponies; Murray MJ et al.; Isolated segments of left dorsal colon and a side-to-side colocolostomy (between the left ventral colon and left dorsal colon) were surgically created in 6 adult ponies . Four segments, each separated by an empty segment, were inoculated (20 ml) with 1 of the following 4 solutions: phosphate buffered saline solution (PBSS)/1% polyethylene glycol (PEG); purified cholera toxin in PBSS/1% PEG (5 micrograms cholera toxin/ml of PBSS/1% PEG); lyophilized Salmonella typhimurium UCD 1755 culture lysate, reconstituted in PBSS/1% PEG; and viable S typhimurium UCD 1755 (10(8) organisms/ml of PBSS/1% PEG) . Twenty hours following inoculation of the treatment solutions into the isolated colon segments, the ponies were reanesthetized . Fluid accumulation in the isolated segments was measured, and tissue samples from isolated segments were taken for examination by light microscopy and electron microscopy, and for measurement of mucosal cyclic adenosine monophosphate levels . There was fluid accumulation in segments inoculated with cholera toxin in 4 ponies (29.5 +/- 12.7 ml), and in segments inoculated with S typhimurium UCD 1755 culture lysate in 3 ponies (14.0 +/- 8.7 ml) . There was no fluid accumulation in segments inoculated with either the control solution (PBSS/1% PEG) or viable S typhimurium UCD 1755 . There was significantly (P less than 0.05) less cyclic adenosine monophosphate in segments inoculated with cholera toxin, Salmonella lysate, and viable Salmonella, compared with control segments . Histologically, there were minimal changes in control segments, consisting of mild to moderate submucosal edema and capillary congestion.(ABSTRACT TRUNCATED AT 250 WORDS)

Environ Mol Mutagen, 1989, 13(2), 116 - 27
Mutagenicity of nitro compounds in Salmonella typhimurium in the presence of flavin mononucleotide in a preincubation assay; Dellarco VL et al.; A series of nitro compounds (18 aromatic and one aliphatic) was evaluated using a modification of the standard Salmonella typhimurium mutagenicity assay . A preincubation protocol was used with flavin mononucleotide (FMN) incorporated into the assay mixture to facilitate nitro reduction . Several aromatic nitro compounds (m-nitroaniline, p-nitroaniline, 2,6-dinitrotoluene, 2,4-dinitrotoluene,2,3-dinitrotoluene,1,8-dinitronaphthalene), which were negative or only weakly mutagenic when tested in the standard plate incorporation assay, showed FMN-dependent mutagenic responses with this procedure . For some nitro compounds, the addition of FMN was not needed for the detection of mutagenicity in the modified protocol . Not all nitro compounds were positive using the preincubation procedure with FMN . The lack of mutagenicity, however, does not appear to be the result of the inability of the modified method to reduce nitro compounds, since it was found that reduction does occur under the assay conditions for the two nonmutagens evaluated for nitro reduction (nitrobenzene and p-nitrophenol) . It is suggested that the modified protocol may be useful for evaluating the mutagenicity of many nitro compounds.

J Bacteriol, 1989 Jan, 171(1), 612 - 5
recB and recC genes of Salmonella typhimurium; Mahan MJ et al.; We have investigated the genetic organization of the recB (exonuclease V) and recC (exonuclease V) genes of Salmonella typhimurium . A detailed genetic map is constructed that includes the relative order in the chromosome, P22 cotransduction frequencies, and the orientation of transcription of the recB and recC genes . In addition, the isolation and characterization of Mu dJ insertion mutations in recB and recC are discussed.

J Bacteriol, 1989 Jan, 171(1), 538 - 46
Gene replacement and retrieval with recombinant M13mp bacteriophages; Blum P et al.; We have developed an allele exchange system for shuttling sequences of DNA to and from their original chromosomal loci . Cloned segments of the histidine operon of Salmonella typhimurium and the lactose operon of Escherichia coli served as target sequences and were used to develop the system . Replacement and retrieval of target sequences used the phage M13mp vectors and proceeded through an M13 lysogen intermediate . The intermediates and products of allele exchange were characterized by genetic and hybridization analyses . Several unique properties of M13 lysogens were exploited to devise positive selections to detect integration and excision . These positive selections were used to manipulate phenotypically silent alleles.

J Bacteriol, 1989 Jan, 171(1), 254 - 62
Homology between virF, the transcriptional activator of the Yersinia virulence regulon, and AraC, the Escherichia coli arabinose operon regulator; Cornelis G et al.; Virulent yersiniae (Yersinia pestis, Y . pseudotuberculosis, and Y . enterocolitica) restrict their growth at 37 degrees C in rich medium deprived of calcium . This property, called calcium dependency, correlates with the secretion of Yersinia outer membrane proteins (Yops) and with pathogenicity . It is mediated by a 70-kilobase plasmid called pYV . The structural genes of the Yops (yop genes), as well as genes involved in the control of their expression (vir genes), have been localized on pYV . In this communication we show that virF encodes a transcriptional activator controlling the yop regulon . This activator is a 30,879-dalton protein related to AraC, the regulator of the Escherichia coli and Salmonella typhimurium arabinose operons . We also show in this paper that transcription of virF is thermodependent and presumably autoregulated . virF is thus responsible for the effect of temperature on the production of the Yops . Finally, we show that virF activates transcription of the yop genes independently of the presence of calcium ions . The role of calcium therefore remains unaccounted for.

Can J Vet Res, 1989 Jan, 53(1), 84 - 6
Survival of Salmonella typhimurium and Staphylococcus aureus in Genoa salami of varying salt concentration; Messier S et al.; Genoa salami prepared using three different salt concentrations (2.0, 2.75 and 3.3%) were inoculated with 2.0 x 10(3) and 1.1 x 10(3) bacteria/g of Salmonella typhimurium and Staphylococcus aureus respectively . Over a period of 74 days samples were taken and analyzed for water activity and pH, counts of S . aureus and presence of Salmonella . After 11 days of dry-curing Salmonella could no longer be detected by preenrichment followed by selective enrichment procedures . Viable S . aureus were still found after 74 days of dry-curing . The results of this study would suggest that water activity and pH measurements are useful in evaluating the safety of dry-cured products.

Mutat Res, 1989 Jan-Feb, 225(1-2), 15 - 9
Studies on the oxidation products from 2,4-diaminotoluene by hydrogen peroxide and their mutagenicities . II; Watanabe T et al.; 2,4-Diaminotoluene (DAT) was reacted with hydrogen peroxide at room temperature for 2 days, and the resulting red precipitates were separated into 5 fractions on silica gel column chromatography . On the gas chromatographic (GC) study, the first fraction (Fr . 1), which is mutagenic (1425 and 1391 revertants/micrograms in the absence and presence of S9 respectively) in Salmonella typhimurium TA98, contained several peaks . Fr . 1 was further separated into 4 subfractions (Fr . 1-I-Fr . 1-IV) by silica gel column chromatography . The red crystals were separated from Fr . 1-III and the structure of the compound was determined to be 1,8-diamino-2,7-dimethylphenazine from physicochemical and chemical evidence . Further, o-nitro-p-toluidine, p-nitro-o-toluidine, 3,3'-diamino-4,4'-dimethylazobenzene and 3,3'-diamino-4,4'-dimethylazoxybenzene were identified with authentic and synthesized samples by gas chromatography/mass spectrometry . These compounds without nitrotoluidines were mutagenic, and phenazine, azo and azoxy compounds induced 49, 301 and 245 revertants/nmole in Salmonella typhimurium TA98 with 25 microliters S9 per plate, respectively.

Mutat Res, 1989 Jan, 222(1), 9 - 18
Activation of two environmental mixtures by plant S9; Shane BS et al.; Nitrated and ozonized pyrene mixtures were assayed for their mutagenic activity in the presence or absence of pea S9 using Salmonella typhimurium TA98 as the indicator organism . The plant enzymes increased the mutagenic response of these mixtures above that obtained in the absence of S9 . The optimum S9 protein concentration for the activation of the nitrated pyrene mixture at 0.1 microgram was 3.9 mg/plate whereas that for the ozonized pyrene mixture at 33.3 micrograms was 3.2 mg protein/plate . BSA could not replace S9, and NADPH was a required co-factor in the activation of both mixtures by pea S9 . Although the nitrated pyrene mixture was determined to consist of approximately 90% 1-nitropyrene, the mutagenic response due to this compound ranged from 30 to 50% of that of the mixture.

Mutat Res, 1989 Jan, 222(1), 53 - 61
Mutagenicity studies on fenitrothion in bacteria and mammalian cells; Hara M et al.; The mutagenicity of fenitrothion was determined in strains of Salmonella typhimurium and Escherichia coli . Fenitrothion was found to be non-mutagenic in Salmonella typhimurium strains of TA98, TA1535 and TA1537 and in Escherichia coli WP2uvrA both with and without S9 mix, while weak mutagenicity was observed only in Salmonella typhimurium TA100 and enhanced by the addition of S9 mix . The mutagenicity observed in the TA100 strain was not expressed in a nitroreductase-deficient strain, TA100 NR, and decreased in a transacetylase-deficient strain, TA100 1,8-DNP6 . The mutagenicity of fenitrothion was also examined by a gene mutation assay using the gene for hypoxanthine-guanine phosphoribosyltransferase (hgprt) in V79 Chinese hamster lung cells . Fenitrothion did not induce any increment of 6-thioguanine-resistant mutant cells at doses ranging from 0.01 to 0.3 mM regardless of the presence or absence of S9 mix . These results suggest that reduction of fenitrothion by a bacterial nitroreductase of TA100 to an active form is essential for the expression of the mutagenicity of fenitrothion in TA100 and that a bacterial transacetylase of TA100 also has an important role in the process of mutagenic activation.

Mutat Res, 1989 Jan, 222(1), 19 - 25
Comparative antimutagenicity of 5 compounds against 5 mutagenic complex mixtures in Salmonella typhimurium strain TA98; Ong T et al.; Using the Ames Salmonella/microsome assay, we compared the antimutagenic activities of chlorophyllin, retinol, beta-carotene, vitamin C, and vitamin E against solvent extracts of coal dust, diesel emission particles, airborne particles, fried beef, and tobacco snuff . The results show that chlorophyllin inhibited 69% of the mutagenic activity of tobacco snuff and over 90% of that of the other 4 complex mixtures . Retinol inhibited 29-48% of the mutagenic activity of all 5 complex mixtures . beta-Carotene, vitamin C, and vitamin E inhibited, if any, less than 39% of the activity of the complex mixtures studied . Vitamin C enhanced the mutagenicity of airborne particles . These results indicate that for these dietary and environmental complex mixtures chlorophyllin is a more effective antimutagen than retinol, beta-carotene, vitamin C, and vitamin E.

Environ Mol Mutagen, 1989, 13(1), 1 - 24
Reevaluation of the mutagenicity and carcinogenicity of chemicals previously identified as "false positives" in the Salmonella typhimurium mutagenicity assay; Prival MJ et al.; An accurate determination of the correlation between the carcinogenicity and the mutagenicity of chemicals has been hampered by the lack of a well-documented list of noncarcinogens . To overcome this problem, Shelby and Stasiewicz (Environ Mutagen 6:871-878, 1984) published a list of 70 chemicals that showed no evidence of carcinogenicity in the National Cancer Institute (NCI) or National Toxicology Program (NTP) rodent carcinogenesis bioassays . More recently, Tennant et al . (Science 236:933-941, 1987) published a list of chemicals, including 29 noncarcinogens, that had been adequately tested for carcinogenicity by the NTP . Of the chemicals listed by Shelby and Stasiewicz or by Tennant and co-workers as noncarcinogenic, the NTP has evaluated 25 as mutagenic in Salmonella typhimurium; 48 of the noncarcinogens were evaluated as nonmutagenic . Thus, of the 73 noncarcinogens that have been evaluated as either positive or negative for mutagenicity, 34% (25/73) were "false positives" (mutagenic noncarcinogens) in the S . typhimurium assay . We re-evaluated the same mutagenicity and carcinogenicity data to determine whether the frequency of "false positives" is really as high as it appears to be . Our reevaluation of the mutagenicity data used more stringent criteria for calling a compound mutagenic than those used by the NTP, resulting in a substantial reduction in the frequency of "false positives" in the S . typhimurium mutagenicity assay . However, application of these same stringent criteria also substantially reduced the frequency of "true positives" (mutagenic carcinogens) . Thus, it is concluded that modification of the evaluation criteria for the mutagenicity test can increase the specificity of the assay for the detection of carcinogens, but only at the cost of a corresponding reduction in sensitivity . We also performed a separate reevaluation of the NCI/NTP carcinogenicity data for the 25 S . typhimurium "false positives," assuming that the NTP evaluations of the mutagenicity data were correct . These reevaluations were based on the methodologies and findings of Griesemer and Cueto (In Montesano R, Bartsch H, Tomatis L (eds): Molecular and Cellular Aspects of Carcinogen Screening Tests.(ABSTRACT TRUNCATED AT 400 WORDS)

Carcinogenesis, 1989 Jan, 10(1), 87 - 90
Application of an immunoassay for cyclic acrolein deoxyguanosine adducts to assess their formation in DNA of Salmonella typhimurium under conditions of mutation induction by acrolein; Foiles PG et al.; Acrolein has been shown to form cyclic deoxyguanosine adducts when it reacts with DNA in vitro . In this study, we have used a recently developed immunoassay for these adducts to study their formation in DNA from Salmonella typhimurium exposed to acrolein . Acrolein--deoxyguanosine adducts were formed in a dose-dependent fashion in Salmonella tester strains TA100 and TA104, reaching levels as high as 5 mumol adduct per mol deoxyguanosine . Using the liquid pre-incubation assay, acrolein-induced mutations were also found in strains TA100 and TA104 . The correlation between acrolein--deoxyguanosine adduct concentration and acrolein-induced mutations in TA100, which contains GC base pairs at the site of reversion, suggests that the acrolein--deoxyguanosine adduct is a promutagenic lesion . That mutations are also seen in TA104 which contains AT base pairs at the site of reversion suggest that adducts of bases other than deoxyguanosine may also be important in the mutagenic activity of acrolein.

Carcinogenesis, 1989 Jan, 10(1), 49 - 54
Different mechanisms are involved in DNA damage, bacterial mutagenicity and cytotoxicity induced by 1,2-dibromo-3-chloropropane in suspensions of rat liver cells; Holme JA et al.; 1,2-Dibromo-3-chloropropane (DBCP) induced DNA damage, measured by an automated alkaline elution method, in suspensions of rat liver parenchymal cells at low concentrations (1-10 microM) . At much higher concentrations (0.5-2.5 mM), DBCP was metabolized to products that were mutagenic to Salmonella typhimurium TA100 co-incubated with the liver cells . At these higher concentrations a marked depletion of cellular glutathione was seen and at 2.5 mM DBCP was cytotoxic . Perdeuterated DBCP (D5-DBCP) caused less DNA damage in the liver cells than DBCP, most likely because of decrease in cytochrome P-450 dependent metabolism . A more pronounced decrease in mutagenicity occurred with D5-DBCP compared to DBCP, whereas the two compounds were equally cytotoxic . Preincubation of the liver cells with diethylmaleate or buthionine sulfoximine, to lower cellular levels of glutathione, decreased DBCP induced DNA damage . The decrease in DNA damage was proportional to the decrease in cellular glutathione levels . In contrast, diethylmaleate enhanced DBCP-induced bacterial mutagenicity and cellular cytotoxicity . The cytotoxic effect could be partly blocked by addition of ascorbate . From the data presented we suggest that: (i) cytochrome P-450 dependent oxidation as well as glutathione conjugation are involved in DBCP induced DNA damage, (ii) cytochrome P-450 dependent oxidation leads to formation of products mutagenic to bacteria and (iii) the cytotoxicity induced by DBCP in the liver cells in vitro is caused by oxidative damage following glutathione depletion and/or direct membrane damage.

Mutat Res, 1989 Jan, 210(1), 113 - 25
Influence of uvrB and pKM101 on the spectrum of spontaneous, UV- and gamma-ray-induced base substitutions that revert hisG46 in Salmonella typhimurium; Eisenstadt E et al.; Oligonucleotide probes were used to identify base substitutions in 1089 revertants of hisG46 in Salmonella typhimurium that arose spontaneously or following irradiation with UV- or gamma-rays . The hisG46 allele, carrying a mutant CCC codon (Pro) in place of the wild-type codon CTC (Leu69) reverted via 6 distinguishable mutational events--C to T transitions at codon sites 1 or 2, C to A or C to G transversions at codon site 1, C to A at codon site 2, and an extragenic suppressor mutation . The distribution of hisG46 revertants differed among treatments and was influenced by the DNA-repair capacity of the bacteria . Plasmid pKM101 enhanced the frequencies of both spontaneous and induced mutations; transversion events were enhanced more efficiently by pKM101 than were transition events . Compared to Uvr+ bacteria, Uvr- bacteria had higher frequencies of spontaneous and induced mutations; transition mutations were enhanced more efficiently than were transversion mutations . The influence of DNA-repair activities on the mutational spectra provides some insights on the origins of spontaneous and UV-induced mutations.

Infect Immun, 1989 Jan, 57(1), 1 - 7
Intracellular survival of wild-type Salmonella typhimurium and macrophage-sensitive mutants in diverse populations of macrophages; Buchmeier NA et al.; Salmonella typhimurium survives within macrophages and causes a fatal infection in susceptible strains of mice . A number of S . typhimurium mutants that contain Tn10 insertions in genes which are necessary for survival within the macrophage have been isolated . To demonstrate the importance of each gene in intracellular survival, the mutations were transduced into a smooth-strain background and the ability to survive intracellularly was assayed in five different populations of macrophages . The majority of the original macrophage-sensitive mutants retained the macrophage-sensitive phenotype in the smooth-strain background . The ability to survive or grow within macrophages varied with both the source of macrophages and the individual mutants . S . typhimurium grew best in the macrophage-like cell line J774, survived at moderate levels in splenic and bone marrow-derived macrophages, and was killed most efficiently in peritoneal macrophages . Macrophage-sensitive mutants transduced into a smooth background were also less virulent than the parent, with a 50% lethal dose of 2 to 5 logs greater than that of the parental strain . These experiments demonstrate that survival of S . typhimurium within macrophages varies with the source of cells, with a distinct ability to survive in macrophages from mouse spleens, where S . typhimurium grows rapidly . These experiments also demonstrate the heterogeneity in intracellular survival among the various macrophage-sensitive mutants, which may reflect the relative importance of the individual mutated genes in survival within macrophages.

Eisei Shikenjo Hokoku, 1989, (107), 21 - 5
{Alpha-bromocinnamaldehyde, its mutagenicity and contents in commercial products}; Kojima S et al.; The amount of alpha-bromocinnamaldehyde (BCA), an anti-mildew agent, in some commercial products, was examined by high performance liquid chromatography (HPLC) using the following conditions: column, Nucleosil 50-5 (Nagel, 250 mm x 4.6 mm i.d.); mobile phase, hexane-chloroform (12:5); flow rate, 1.0 ml/min; detector, ultraviolet detector; detection wavelength, 290 nm . Large amounts of BCA were detected in anti-mildew mat (10,700-43,500 micrograms/g), anti-mildew cloth (1,100 micrograms/g) and BCA gel (10,050 micrograms/g) . BCA was also tested for mutagenicity against Salmonella typhimurium TA100, TA98 and TA2637, with and without metabolic activation (S9 mix) . The result showed that BCA was a very potent mutagen and induced 1.0 x 10(6) of revertants per mg against TA100 without S9 mix . The mutagenicity decreased to 1.3 x 10(4) revertants per mg in the presence of S9 mix.

Ann Ist Super Sanita, 1989, 25(4), 591 - 4
Monitoring of urban air pollution by mutagenicity assays; Crebelli R; Urban air particulate extracts were assayed for mutagenicity in Salmonella typhimurium strain TA98 and in the nitroreductase deficient derivatives TA98NR and TA98/1,8DNP6 . The results obtained indicate a low contribution of nitropyrenes from diesel exhausts to air particulate mutagenicity in the city of Rome . Fractionation of extracts into acidic, basic and neutral components showed that neutral compounds account for about two-thirds of the total mutagenic activity . No significant mutagenic activity was detected in body fluids of rodents treated with airborne particulate extracts nor in the micronucleus test in mice . Basic and neutral fractions of air particulate extracts proved to inhibit liver aminopyrine-N-demethylase in the mouse.

Nat Immun Cell Growth Regul, 1989, 8(6), 331 - 7
The role of natural killer cells in experimental murine salmonellosis; Smith RA et al.; This study was designed to determine if murine natural killer (NK) cells play a role in host protection against a Salmonella typhimurium challenge infection . Outbred ICR mice injected intravenously with either attenuated (RIA strain) or virulent (SR-11 strain) salmonellae elicited enhanced killing of YAC-1 targets, which was maximal at 24 h after challenging . When NK cells were depleted with antiasialo GM1 prior to challenging, the splenic bacterial numbers were significantly less in this group of mice compared to sham-injected and challenged animals . The rabbit antiasialo GM1 sera had no detectable direct or indirect effect on the salmonellae . Our results indicate that the NK or natural suppressor cells may be functioning as down-regulators.

Trans R Soc Trop Med Hyg, 1989 Jan-Feb, 83(1), 133 - 5
Bacterial pathogens isolated from cockroaches trapped from paediatric wards in peninsular Malaysia; Oothuman P et al.; A survey was conducted in 4 paediatric wards in Malaysia to determine the distribution of various species of cockroaches and to examine their gut contents for bacteria . Cockroaches were trapped from food dispensing areas (kitchens), store rooms, cupboards and open wards . 104 cockroaches were caught, consisting of Periplaneta americana (67.3%), Blattella germanica (26%), P . brunnea (4.8%), and Supella longipalpa (1.9%) . Bacteria were isolated from all cockroaches except 3 P . americana . Many bacterial species were identified, including the pathogenic and potentially pathogenic species Shigella boydii, S . dysenteriae, Salmonella typhimurium, Klebseilla oxytoca, K . ozaena and Serratia marcescens.

Teratog Carcinog Mutagen, 1989, 9(4), 211 - 8
Hydrogen peroxide mutagenicity towards Salmonella typhimurium; Kensese SM et al.; In bioassays conducted under controlled, comparable conditions, weak direct mutagenicity responses were observed for hydrogen peroxide in the standard (Ames test) agar plate incorporation bioassay with Salmonella typhimurium strains TA97, TA98, TA102, and TA1537, in a 20 min preincubation test with strains TA97, TA98, TA100, TA102, TA1537, and TA1538, and in a liquid incubation modification using strain TA1537 . These results conclusively demonstrate that hydrogen peroxide is a weak mutagen, especially in strains that are sensitive to oxidative damage under suitable bioassay conditions.

Teratog Carcinog Mutagen, 1989, 9(3), 133 - 45
Mutagenic lipid peroxides from edible oils; Kensese SM et al.; Weak mutagenic activity was detected in several commercially available edible palm and corn oils using liquid incubation bioassays with Salmonella typhimurium TA1537 . Chromatographic fractionation of unrefined palm oil established that mutagenic activity was present in three fractions that also contained fatty acyl hydroperoxides . Similar weak mutagenic activity was also demonstrated for linoleic and linolenic acid hydroperoxides . In all cases, the mutagenicity was abolished by exogenous catalase, implying that the observed activity was moderated by hydrogen peroxide.

Environ Mol Mutagen, 1989, 14(2), 115 - 22
Mutagenicity of some alkyl nitrites used as recreational drugs; Dunkel VC et al.; When the AIDS epidemic was in its earliest stages, and prior to identification of HIV as the etiological factor, the use of volatile nitrites by the male homosexual community to enhance sexual activities appeared to have a significant role in this disease . Preliminary observations indicated that the portion of the male homosexual community which developed Kaposi's sarcoma were also heavy nitrite users . These nitrites had been demonstrated to be mutagenic in bacteria and thus it was postulated that they could be responsible for the appearance of the sarcoma . To evaluate further the genotoxic activity of these chemicals, six nitrites, including those most commonly used by homosexuals for sexual gratification, were selected for testing in the mouse lymphoma TK+/- and Salmonella typhimurium mutagenicity assays . One chemical, n-amyl nitrite, was negative in the mouse lymphoma assay, while the other five chemicals, n-butyl, isobutyl, iso-amyl, sec-butyl, and n-propyl nitrite, were positive . All six compounds were positive in the Salmonella assay . The mutagenic and known toxic effects of these chemicals remain a concern because a large population of teenagers and young adults continue to abuse these substances.

Microbiol Immunol, 1989, 33(12), 1063 - 7
Specificity of Salmonella porin as an eliciting antigen for cell-mediated immunity (CMI) reaction in murine salmonellosis; Matsui K et al.; The specificities of Salmonella porin on elicitations of delayed-type hypersensitivity (DTH) reaction and interleukin-2 (IL-2) production in BALB/c mice immunized with Salmonella typhimurium were examined . Only porin from S . typhimurium was capable of eliciting significant levels of DTH and IL-2 production in S . typhimurium-immunized mice, whereas no significant DTH and IL-2 production were induced by porin from Salmonella enteritidis or Escherichia coli . Our observations suggested that Salmonella porin was a serovar-specific antigen for the elicitation of cell-mediated immunity (CMI) in salmonellosis.

Arch Microbiol, 1989, 153(1), 26 - 32
Characterization of phosphoenolpyruvate synthase mutants in Salmonella typhimurium; Smyer JR et al.; The enteric bacteria are able to grow by utilizing three-carbon compounds (pyruvate, lactate, and alanine) as sole carbon sources only if they have a functional phosphoenolpyruvate synthase (PEP synthase) . PEP synthase catalyzes the phosphorylation of pyruvate to PEP with the hydrolysis of ATP to AMP . This anaplerotic reaction is needed for the synthesis of carbohydrates and citric acid cycle intermediates that are essential for continued cell growth . Insertion mutants were isolated in Salmonella typhimurium that specifically lack the ability to grow on three-carbon compounds . These mutants also fail to utilize acetate as a sole carbon source . Enzyme assays were performed and the results showed that these mutants contain no PEP synthase activity . By using bacteriophage P22, the pps mutations isolated in this study were found to be contransducible with genetic markers in both the aroD and btuC genes . Three-factor crosses pinpointed the order of these genes and their distances with respect to each other . One of the mutants carries a pps::lac operon fusion . This fusion was used to explore the transcriptional regulation of the pps gene . A functional copy of the pps gene is required for its own induction . The pps gene is also under catabolite repression, but the addition of adenosine 3',5'-cyclic monophosphate (cyclic AMP) to cells grown in the presence of glucose does not relieve this repression . These results indicate that the synthesis of PEP synthase is regulated in a more complex manner than has been previously recognized.

Arch Microbiol, 1989, 152(6), 584 - 8
Isolation and characterization of oxaloacetate decarboxylase of Salmonella typhimurium, a sodium ion pump; Wifling K et al.; Anaerobic growth of Salmonella typhimurium on citrate is Na+-dependent and requires induction of the necessary enzymes during a 20-40 h lag phase . The citrate fermentation pathway involves citrate lyase and oxaloacetate decarboxylase . The decarboxylase is a membrane-bound, Na+-activated, biotin-containing enzyme that functions as a Na+ pump . Oxaloacetate decarboxylase was isolated by affinity chromatography of a Triton X-100 extract of the bacterial membranes on avidin-Sepharose . The enzyme consists of three subunits alpha, beta, gamma, with apparent molecular weights of 63,800, 34,500 and 10,600 . The alpha-chain contains a covalently attached biotin group and binds to antibodies raised against the alpha-subunit of oxaloacetate decarboxylase from Klebsiella pneumoniae . The Na+ transport function was reconstituted by incorporation of the purified enzyme into proteoliposomes.

Microbiol Immunol, 1989, 33(9), 699 - 708
Protective immunity induced by porin in experimental mouse salmonellosis; Matsui K et al.; The induction of protective immunity to mouse salmonellosis by porin from Salmonella typhimurium LT2 was studied . The immunization with porin induced a high level of protective immunity to salmonellosis in BALB/c mice . Mice immunized with porin exhibited significant levels of delayed-type hypersensitivity response and interleukin-2 production, indicating that porin was capable of inducing cell-mediated immunity (CMI) . Furthermore, we found that both T cells and sera taken from the porin-immunized mice could transfer the protection against salmonellosis into nonimmunized mice . These observations suggested that a high level of the protection to salmonellosis obtained by the porin immunization resulted from the induction of CMI in addition to humoral immunity.

Environ Mol Mutagen, 1989, 13(4), 343 - 6
Mutagenicity of the human carcinogen treosulphan in Salmonella; Zeiger E et al.; The human carcinogen treosulphan was mutagenic in Salmonella typhimurium TA100 and TA1535, as was dl-1,2:3,4-diepoxybutane (DEB), a proposed hydrolysis product of treosulphan . Another proposed hydrolysis product, methane- sulfonic acid, was not mutagenic in these strains . The pattern of the mutagenic responses at pH 6,7, and 8 to treosulphan and DEB suggests that DEB formation may be responsible for the mutagenicity of treosulphan.

Plasmid, 1989 Jan, 21(1), 48 - 58
Novel virulence properties of the Salmonella typhimurium virulence-associated plasmid: immune suppression and stimulation of splenomegaly; Hoertt BE et al.; Mice infected subcutaneously with wild-type Salmonella typhimurium, SR11, developed a significant splenomegaly when compared with mice infected with an equal number of a plasmid-cured strain . Further, the bacterial load in the spleen at 14 days after infection, measured as colony-forming units per gram tissue, was significantly higher in mice infected with the parent strain than in mice infected with the plasmid-cured strain . These data confirm the previously reported plasmid-associated ability of Salmonella to multiply within the spleen . In addition, lymph node cells (LNC) from mice infected with the parent strain had a significantly reduced ability to proliferate in response to concanavalin A, a T-cell mitogen, and to heat-killed S . typhimurium cells when compared with LNC isolated from mice infected with the plasmid-cured strain . Finally, reintroduction of a functional Tn5-tagged 90-kb plasmid into a plasmid-free strain restored its capacity to cause a marked splenomegaly and to suppress lymph node cell proliferation in BALB/c mice . These data demonstrate that the 90-kb plasmid of highly virulent S . typhimurium strains mediates several novel pathogenic properties in infected mice: (1) enhancement of the ability of Salmonella to multiply within the spleen; (2) stimulation of a splenic inflammatory response as displayed by marked splenomegaly; and (3) a general suppression of lymphocyte responsiveness to both T-cell mitogens and specific Salmonella antigens.

Mol Gen Genet, 1989 Jan, 215(2), 358 - 63
Genetic studies of mutants in a high-affinity methionine transport system in Salmonella typhimurium; Cottam AN et al.; A total of 30 metP mutations defective in the high-affinity methionine transport system were linked in P1 transduction to the zaf-1351::Tn10 insertion mutation at min 5-6 on the Salmonella typhimurium chromosome map . The relationship of metP to several other markers in this region was studied . Methionine transport was strongly inhibited by arsenate, suggesting that the metP system belongs to the shock-sensitive category and possesses a periplasmic binding protein . However, other experiments provided less clear cut evidence . Transport activity was only slightly reduced by osmotic shock; a methionine binding activity was detected in shock fluids from the wild-type strain, and although this activity was reduced by 50% in 3 frameshift mutants, mutants without any activity were not found . No differences were detected in the shock fluids of the 30 mutants when examined by SDS-polyacrylamide gel electrophoresis.

Genetics, 1989 Jan, 121(1), 13 - 28
Fine structure genetic and physical map of the phage P22 tail protein gene; Berget PB et al.; Bacteriophage P22 which are incapable of making functional tail protein can be propagated by the addition of purified mature tail protein trimers to either liquid or solidified medium . This unique in vitro complementation condition has allowed us to isolate 74 absolute lethal tail protein mutants of P22 after hydroxylamine mutagenesis . These phage mutants have an absolute requirement for purified P22 tail protein to be present in a soft agar overlay in order to form plaques and do not grow on any nonsense suppressing strains of Salmonella typhimurium . In order to genetically map and physically locate these mutations we have constructed two complementary sets of fine structure deletion mapping strains using a collection of Tn1 insertions in gene 9, the structural gene for the tail protein . Fourteen bacteriophage P22 strains carrying unique Tn1 transposon insertions (Ap phage) in gene 9 have been crossed with Ap phage carrying Tn1 insertions in gene 20 . Phage carrying deletions that arose from homologous recombination between the Tn1 elements were isolated as P22 lysogens . The deletion prophage were shown to be missing all genetic information bracketed by the parental Tn1 elements and thus form a set of deletions into gene 9 from the 5' end of the gene . From the frequency of production of these deletion phage the orientation of the Tn1 insertions in gene 9 could be deduced . The genetic end points of the deletions in gene 9 and thus the order of Tn1 insertions were determined by marker rescue experiments using the original Ap phage . The genetic end points of the deletions in gene 20 were determined in similar experiments using nonsense mutations in gene 20 . To locate the physical end points of these deletions in gene 9, DNA containing the Tn1 element has been cloned from each of the original Ap phage into plasmids . The precise point of insertion of Tn1 into gene 9 was determined by restriction enzyme mapping and DNA sequencing of the relevant portions of each of these plasmids . In vitro deletion of different 3' gene 9 sequences in the plasmid clones was accomplished through the use of unique restriction endonuclease sites in Tn1 . The resulting plasmids form a set of deletions extending into the 3' end of the gene which are complementary compared to the deletion lysogens.(ABSTRACT TRUNCATED AT 400 WORDS)

Environ Mol Mutagen, 1989, 13(2), 100 - 6
Mutagenicity and induction of sister chromatid exchange by optically active enantiomers of secondary butyl methanesulfonate; Ball JC et al.; This report describes experiments in which a chiral alkyl methanesulfonate was used to investigate possible mechanisms by which alkylating agents cause their mutagenic, cytotoxic, and clastogenic effects . Optically active enantiomers and the racemic mixture of 2-butyl methanesulfonate (2-BMS) were cytotoxic and mutagenic in Chinese hamster V79 cells and in AS52 cells and mutagenic in Salmonella typhimurium strains TA100 and TA1535 (without the addition of exogenous metabolizing systems) . Within the experimental uncertainties, the cytotoxicity and mutagenicity curves were the same for the R and S enantiomers and for the racemic mixture . The 2-BMS isomers were cytotoxic and induced sister chromatid exchanges (SCE) in CHO-K1-BH4 cells . The cytotoxicity curve was similar to that observed with V79 and AS52 cells . The induction of SCE was linear between 1 and 6 mM 2-BMS with no differences discernable between the isomers . The results can be interpreted two ways . The first interpretation is that 2-BMS reacts via a carbocation, and the second interpretation involves an SN2 reaction of 2-BMS with DNA . The latter interpretation suggests that the mechanisms of mutagenesis, cytotoxicity, or the induction of SCE cannot distinguish between small (four-carbon) optically active DNA adducts . We favor the second interpretation because of solvolysis experiments showing the complete inversion of configuration of optically active 2-octyl methanesulfonate (2-OMS, Weiner and Sneen: J American Chemical Society 87:287-291, 1965) . While we assume that optically active 2-BMS will react using the same mechanism as chiral 2-OMS, we cannot exclude the possibility that 2-BMS reacts via a carbocation intermediate.

J Bacteriol, 1989 Jan, 171(1), 263 - 71
Characterization and sequence analysis of the scrA gene encoding enzyme IIScr of the Streptococcus mutans phosphoenolpyruvate-dependent sucrose phosphotransferase system; Sato Y et al.; The Streptococcus mutans GS-5 scrA gene coding for enzyme IIScr of the phosphoenolpyruvate-dependent sucrose phosphotransferase system (PTS) was localized upstream from the scrB gene coding for sucrose-6-phosphate hydrolase activity after Mu dE transposon mutagenesis of plasmid pMH613 . The cloned scrA gene product was identified as a 68-kilodalton protein by minicell analysis after isolation of the gene in plasmid pD4 . In addition, the membrane fraction from Escherichia coli cells containing pD4 exhibited sucrose PTS activity upon complementation with enzyme I and HPr from strain GS-5 . The nucleotide sequence of the scrA region revealed that this gene was located immediately upstream from the scrB gene and divergently transcribed from the opposite DNA strand . The scrA gene was preceded by potential Shine-Dalgarno and promoterlike sequences and was followed by a transcription terminator-like sequence . The scrA gene coded for an enzyme IIScr protein of 664 amino acid residues with a calculated molecular weight of 69,983 . This enzyme IIScr protein was larger than the comparable proteins from Bacillus subtilis and E . coli containing sucrose-metabolizing plasmid pUR400 . The 491-amino-acid N-terminal sequence of the S . mutans enzyme IIScr was homologous with the B . subtilis and E . coli sequences, and the 173-amino-acid C-terminal sequence of the S . mutans protein was also homologous with the Salmonella typhimurium enzyme IIIGlc and the 162-amino-acid C terminus of E . coli enzyme IIBgl . These results suggest that the sucrose PTS system of S . mutans is enzyme III independent.

Biull Eksp Biol Med, 1989 Jan, 107(1), 31 - 3
{Formation of nitric oxide in animal tissues during inflammatory process}; Kubrina LN et al.; EPR evidence was obtained that more intensive formation of mononitrosyl non-heme iron complexes with diethyl-dithiocarbamate (DETC) took place in mouse liver when inflammation process was initiated in mice by the lipopolysaccharide isolated from Salmonella typhimurium bacterium wall DETC intraperitoneally injected bound with endogenous non-heme iron resulted with DETC-Fe complex formation . These complexes were as a traps of nitric oxide appeared in animal tissues, and NO-Fe-DETC complexes were observed . Phenazone known as a free radical process inhibitor lowered NO production in animal organism . The free radical processes were suggested to intensify under inflammation reactions and to cause the various amino groups oxidation to nitroso groups which were capable to release free nitric oxide.

J Immunol, 1989 Jan 1, 142(1), 185 - 94
Complement attack of altered outer membrane areas synthesized after inhibition of the 3-deoxy-D-manno-octulosonate pathway leads to cell death; Goldman RC et al.; Salmonella typhimurium containing specific genes coding for either temperature-sensitive (TS) 3-deoxy-D-manno-octulosonate (KDO) 8-phosphate synthetase or TS cytidine monophosphate-KDO synthetase grow normally when incubated at 30 degrees C and are resistant to C-mediated killing . However, bacteria become avirulent and sensitive to C-mediated killing upon thermal inhibition of TS KDO-8-phosphate synthetase (incubation at 38 degrees C) or TS cytidine monophosphate-KDO synthetase (incubation at 42 degrees C) . Such thermal inhibition concurrently causes synthesis of an altered outer membrane which we now show is the site that renders cells susceptible to C-mediated killing . After incubation of cells in serum, the altered outer membrane area contains C9 in a trypsin-resistant state and membrane attack complex (MAC) lesions observable by electron microscopy . Trypsin-resistant C9 and MAC lesions were also observed in the inner membrane fraction from such serum-treated cells . In contrast, little C9 and few MAC lesions were associated with unaltered outer membrane areas present on these same serum treated cells . Control cells, grown at 30 degrees C and treated with serum (1) bound one-fifth as much C9 as was bound to cells incubated at 42 degrees C, (2) contained only a rare MAC lesion in the outer membrane, and (3) no observable MAC lesions in the inner membrane . We conclude that the altered outer membrane area is the site that renders cells susceptible to insertion of the MAC into both the outer and inner membrane resulting in cell death.

Crit Care Med, 1989 Jan, 17(1), 39 - 47
Physiologic and plasma hormone correlates of survival in endotoxic dogs: effects of opiate antagonists; Murray MJ et al.; Two groups of awake dogs were given an iv bolus of endotoxin (3.0 mg/kg from Salmonella typhimurium); one group (n = 9) was pretreated with either naloxone (2.0 mg/kg iv bolus with 1.7 mg/kg.h; n = 6) or naltrexone (2.0 mg/kg iv bolus with repeat bolus of 1.0 mg/kg at 1, 3 and 5 h; n = 3) and the second group (n = 10) received no opiate antagonist . All of nine dogs that were pretreated with an antagonist survived for 24 h, compared to only five of ten dogs that were not pretreated . Survival correlated with improved BP (mean of 91 vs . 61 mm Hg) and cardiac output (3.9 vs . 2.45 L/min) measured during the first 3 h after the infliction of shock . However, both antagonist-treated and nonantagonist-treated survivors had BP and cardiac output which were statistically lower than their baseline values or saline-treated controls at comparable times . Nonsurvivors had significantly higher levels of norepinephrine (peak level: 1149 ng/ml) and epinephrine (peak level: 31.29 ng/ml) than survivors . Opiate antagonists thus appeared to increase survival in a subgroup of dogs that might not otherwise have survived if they had not been so treated; this survival was associated with improved hemodynamics, but not with increased adrenergic activity.

Res Immunol, 1989 Jan, 140(1), 55 - 65
Suppression of primary antibody response in genetically susceptible mice infected with Salmonella typhimurium: restoration by catalase; Deschenes M et al.; Susceptible C57BL/6 mice infected with a temperature-sensitive mutant of Salmonella typhimurium exhibited a marked depression of in vivo and in vitro primary antibody response to sheep erythrocytes which persisted for several weeks . The antibody response to a T-independent antigen (TNP-polyacrylamide) was also depressed . Cell-mixing experiments indicated that spleen cells from infected animals contained adherent suppressor cells and that the functional activity of T and B cells was unaffected . The antibody response of spleen cells from infected mice was restored by the addition of catalase, suggesting that hydrogen peroxide is involved in the mechanism of suppression.

Mol Gen Genet, 1989 Jan, 215(2), 312 - 6
Bacteriophage P22 as a vehicle for transducing cosmid gene banks between smooth strains of Salmonella typhimurium: use in identifying a role for aroD in attenuating virulent Salmonella strains; Miller IA et al.; A cosmid gene bank of the virulent Salmonella typhimurium C5 was constructed in Escherichia coli K12 . The bank was repackaged into bacteriophage heads and transduced into the semi-rough S . typhimurium strain AS68 which expresses the LamB lambda receptor protein . Approximately 6000 ampicillin-resistant transductants were pooled and used as host for the propagation of bacteriophage P22 . The P22 lysate was able to transduce cosmid recombinants to smooth strains of S . typhimurium and individual transductants were selected which complemented various S . typhimurium auxotrophic mutations . A stable mutation was introduced into the aroD gene of S . typhimurium C5 . The resulting aroD- mutant, named CU038, was highly attenuated compared with the wild-type parent strain and BALB/c mice immunised orally with CU038 were well protected against challenge with the virulent C5 parental strain . Using the cosmid bank repackaged into bacteriophage P22 heads it was possible to isolate cosmid recombinants that could complement the aroD mutation of CU038 either by in vitro selection using minimal medium or in vivo selection for restoration of virulence in BALB/c mice . Repackaged P22 cosmid banks could provide a simple system for selecting in vivo for Salmonella virulence determinants . A Salmonella typhi strain harbouring mutations in aroA and aroD was constructed for potential use as a live oral typhoid vaccine in humans.

Anim Genet, 1989, 20(4), 371 - 81
Genetic and other effects on bacterial phagocytosis and killing by cultured peripheral blood monocytes of SLA-defined miniature pigs; Lacey C et al.; The influence of miniature swine major histocompatibility complex genes (SLA) upon phagocytic and bactericidal activities of peripheral blood monocytes against Salmonella typhimurium and Staphylococcus aureus was measured in vitro using cultured cells and bacterial/enzyme-dependent tetrazolium dye (MTT) reduction . Haplotype significantly influenced uptake and killing of each bacterium by monocytes of 4- and 8-week-old pigs . Cells from 4-week-old SLA ad and aa pigs were significantly better than all others at phagocytizing S . aureus and cells from dg and gg were poorest . Killing of S . aureus was highest at 4 weeks in SLA cd pigs and in dg and gg pigs at 8 weeks of age . Uptake and killing of S . typhimurium was highest in homozygous aa and cc haplotypes at 4 weeks and pigs with the c x d recombinant haplotype had highest uptake and killing of S . typhimurium at 8 weeks . Litter, but not sire, also influenced significantly the uptake and killing of S . aureus and S . typhimurium.

Chem Biol Interact, 1989, 71(4), 367 - 79
Developmental changes in hepatic activation of dietary mutagens by mice; Brennan-Craddock WE et al.; Metabolic activation of the food mutagens 2-amino-3,4-dimethylimidazo{4,5-f}quinoline (MeIQ), 3-amino-1-methyl-5H-pyrido{4,3-b}indole (Trp-P-2) and aflatoxin B1 by female BALB/c mice of different ages (2-24 weeks) was investigated in vivo and in vitro using Salmonella typhimurium TA98 as the indicator organism . The in vivo activation of the three mutagens was investigated in 4- and 24-week-old mice using an intrasanguineous host-mediated assay . All three compounds showed reduced levels of activation with the older hosts . Hepatic S9 fractions from female mice of varying ages between 2 and 24 weeks were used in the in vitro mutagenicity assay . To achieve optimal activation to bacterial mutagens, 5% S9 was required for aflatoxin B1 and Trp-P-2 and 10% S9 for MeIQ; age of donor generally had little effect on the profile of these protein activation curves . Under these optimal conditions MeIQ and Trp-P-2 both exhibited, as before, age-dependent decreases in activation over a wide range of mutagen concentrations, however the in vitro activation of aflatoxin showed no consistent change with age . Spectrophotometric measurements of S9 cytochrome P-450 content showed a decrease in concentration with increasing age, but this was not sufficient to account for changes observed in hepatic mutagen activation . However, changes in the activities of certain cytochrome P-450 isoenzymes and cytosolic GSH-transferases, which in turn result in changes in the activation and detoxification capacity of the liver, would appear to explain age-dependent changes in the activity of mutagens in vivo.

Free Radic Biol Med, 1989, 6(5), 533 - 40
Activation of aromatic amines by prostaglandin H synthase; Josephy PD; Prostaglandin H synthase catalyzes the first step in the synthesis of prostaglandins from arachidonic acid . The peroxidase activity of this enzyme can support the oxidation of xenobiotics, particularly aromatic amines . This pathway of metabolism may contribute to the activation of carcinogenic aromatic amines in target tissues such as the skin, lung, and bladder . In this review, recent work on this subject is summarized . I emphasize the elucidation of the structures of aromatic amine oxidation products, and their interactions with biological macromolecules . Prostaglandin H synthase supports the activation of benzidine to a mutagenic species in the Ames (Salmonella typhimurium) test, and our studies of the mechanism of this activation are described.

Mol Microbiol, 1989 Jan, 3(1), 113 - 8
Partial nucleotide sequence of the pts operon in Salmonella typhimurium: comparative analyses in five bacterial genera; Schnierow BJ et al.; The nucleotide sequence of a Salmonella typhimurium DNA segment of 549 base pairs which encompasses the operator-promoter of the pts operon, the entirety of the ptsH gene, encoding HPr of the phosphotransferase system (PTS), the first 29 nucleotides of the ptsI gene, encoding Enzyme I of the PTS, and the intercistronic region between the ptsH and ptsI genes was determined and compared with the corresponding sequence from Escherichia coli (De Reuse et al., 1985) . The two sequences showed 91% overall identity, with some regions showing sequence conservation and others exhibiting relative divergence . Two open reading frames were identified in both species: one encoded HPr on the 'sense' strand (255 nucleotides; 12 nucleotide differences, no amino acid differences); the other, on the anti-sense strand, consisted of 291 nucleotides (13 nucleotide differences, 13 amino acid differences) . While HPr bears a net negative charge, the putative protein encoded by the open reading frame on the anti-sense strand is strongly basic . Computer analyses of HPr proteins from five different bacterial genera revealed four regions which show strong sequence identity and therefore are presumed to be critical for maintenance of biological activity . Two of these regions were specific to Gram-positive bacteria . Proposed functions for each of these regions are discussed . Relative evolutionary distances between the HPr proteins were also computed.

Agents Actions, 1989 Jan, 26(1-2), 208 - 10
Activation of murine peritoneal macrophages by Salmonella typhimurium; Langermans JA et al.; The results of these studies indicate that the interaction between activated macrophages and S . typhimurium depends on the characteristics of the micro-organism and the kind of activation.

Int Arch Allergy Appl Immunol, 1989, 88(1-2), 40 - 5
Granulocyte/macrophage colony stimulating factor . A potent activation signal for mature macrophages and monocytes; Morrissey PJ et al.; Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a well-characterized hematopoietic growth factor . Recently, using purified recombinant-derived material, we have found that GM-CSF is also a potent activator of mature functional macrophages . Thus, we have found that exogenous GM-CSF augments the primary plaque-forming response to sheep red blood cells and that this effect is due to upregulation of Ia antigen expression and interleukin 1 production by the macrophages . We also show that GM-CSF inhibits the replication of Trypanosoma cruzi in cultured peritoneal macrophages and causes an accelerated clearance of Salmonella typhimurium from the peritoneal cavity of mice . These data indicate that GM-CSF is a multifunctional molecule stimulating both hematopoiesis and mature macrophage function.

Ann Rech Vet, 1989, 20(1), 47 - 55
Infection with a reduced virulence Listeria monocytogenes strain increases resistance to salmonellosis in mice; Kaeffer B et al.; A model to study the non-specific resistance of OF1 mice was standardized using a Listeria monocytogenes strain of reduced virulence to induce this resistance, and a fully virulent Salmonella typhimurium strain (as challenge) to measure it . Dose, route of inoculation and timing were optimized . Kinetics of infection were carried out using Listeria and Salmonella strains respectively, inoculated intravenously and subcutaneously in the hind footpad, in order to minimize the number of dead and uninfected mice . An intravenous inoculation of 1 x 10(4) Listeria colony forming unit (0.25% of the lethal dose 50%) followed up 3 days later by an intravenous challenge of Salmonella (maximum used: 0.15% of the lethal dose 50%) was the optimum way of ensuring a mean infection level of the group stimulated with Listeria that was significantly lower than mean infection level of the controls (P less than 0.01) . Under similar conditions, using a subcutaneous challenge inoculation, this period was of 5 days . An increased resistance against Salmonella was found between days 3 and 9 using an intravenous challenge and between days 3 and 5 using a subcutaneous challenge . Utilization of this non-specific resistance to infection seems to be limited to prevention of expected pathological risks over a relative short period of time.

Proc Natl Acad Sci U S A, 1989 Jan, 86(2), 462 - 5
Evidence for cytochrome P-450NF, the nifedipine oxidase, being the principal enzyme involved in the bioactivation of aflatoxins in human liver; Shimada T et al.; In vitro studies with human liver indicate that the major catalyst involved in the bioactivation of the hepato-carcinogen aflatoxin B1 (AFB1) to its genotoxic 2,3-epoxide derivative is cytochrome P-450NF (P-450NF), a previously characterized protein that also catalyzes the oxidation of nifedipine and other dihydropyridines, quinidine, macrolide antibiotics, various steroids, and other compounds . Evidence was obtained using activation of AFB1 as monitored by umuC gene expression response in Salmonella typhimurium TA1535/pSK1002 and enzyme reconstitution, immunochemical inhibition, correlation of response with levels of P-450NF and nifedipine oxidase activity in different liver samples, stimulation of activity by 7,8-benzoflavone, and inhibition of activity by troleandomycin . Similar results were obtained when levels of 2,3-dihydro-2-(N7-guanyl)-3-hydroxyaflatoxin B1 formed in DNA were measured . P-450NF or a closely related protein also appears to be the major catalyst involved in the activation of aflatoxin G1 and sterigmatocystin, the latter compound being more genotoxic than AFB1 in these systems . Several drugs and conditions are known to influence the levels and activity of P-450NF in human liver, and the activity of the enzyme can be estimated by noninvasive assays . These findings provide a test system for the hypothesis that a specific human disease state (liver cancer) is linked to the level of oxidative metabolism in populations in which aflatoxin ingestion is high.

Carcinogenesis, 1989 Jan, 10(1), 145 - 9
Inhibitory effect of chlorophyll on the genotoxicity of 3-amino-1-methyl-5H-pyrido{4,3-b}indole (Trp-P-2); Negishi T et al.; Genotoxicity of 3-amino-1-methyl-5H-pyrido{4,3-b}indole (Trp-P-2) on Drosophila was suppressed by chlorophyll . Using the wing hair spot test, we found that the formation of mutant hairs in adult flies as a result of feeding them with Trp-P-2 in their larval stage was efficiently inhibited by coadministration of chlorophyll . The decrease in the spot frequencies was dependent on the dose of chlorophyll, and at the highest dose used, where the ratio in weight of Trp-P-2 to chlorophyll was 1:80, a complete prevention of the small single-spot formation was observed . A similar inhibitory effect was detected for chlorophyllin, the chromophore of chlorophyll . In the studies to investigate the mechanism of inhibition, we observed that the mutagenicity of 3-hydroxy-amino-1-methyl-5H-pyrido{4,3-b}indole {Trp-P-2(NHOH)}, the metabolically activated form of Trp-P-2, in Salmonella typhimurium TA98 was suppressed effectively with chlorophyll and chlorophyllin . We also found that chlorophyll and chlorophyllin can produce complexes with Trp-P-2 and Trp-P-2(NHOH) . A straightforward mechanism of these inhibitions is that Trp-P-2 {and Trp-P-2(NHOH)} becomes no longer available to organisms on forming the chlorophyll complex.

J Vet Diagn Invest, 1989 Jan, 1(1), 22 - 4
Systemic salmonellosis in mature beef cows; Morter RL et al.; Systemic infection of mature beef cows with Salmonella typhimurium resulted in death of cows, abortions, and premature births . Salmonella typhimurium was isolated from the kidney, liver, and spleen of cows but not from an aborted fetus . Diarrhea was not a prominent clinical feature of the epizootic . The source of the salmonella was not determined.

Gene, 1989, 76(2), 255 - 69
Physical identification of an internal promoter, ilvAp, in the distal portion of the ilvGMEDA operon; Lopes JM et al.; It has been previously demonstrated that the ilvGMEDA operon is expressed in vivo from the promoters ilvGp2 and ilvEp . An additional internal promoter is identified and designated ilvAp . This internal promoter, which allows independent expression of ilvA, has been analyzed both in vivo and in vitro . Our results indicate that: (1) ilvAp exists in both Escherichia coli K-12 and Salmonella typhimurium, as demonstrated by fusion to the galK reporter gene; (2) ilvAp is located in the distal coding sequence of ilvD; (3) the ilvAp sequences are not identical for these two bacterial species; (4) transcription from ilvAp of E . coli K-12 was demonstrated; (5) expression from ilvAp responds to the availability of oxygen; (6) potential 3' 5'-cyclic AMP receptor protein binding sites exist adjacent to ilvAp.

J Biol Regul Homeost Agents, 1989 Jan-Mar, 3(1), 1 - 7
In vitro treatment of HEp-2 cells with human tumor necrosis factor-alpha and human interferons reduces invasiveness of Salmonella typhimurium; Degre M et al.; Enteroinvasive bacteria, like Salmonella typhimurium, can be internalized in in vitro cultured epithelioidal cells, like HEp-2 cells . This phenomenon is inhibited by pretreatment of cells with human tumor necrosis factor alpha (TNF-alpha) in a dose- and time-dependent manner . The effect was also reproduced in other cell types, including diploid embryo fibroblast cells . The TNF-alpha effect was neutralized by anti-TNF-alpha antibodies . No synergistic effect was produced by combinations of TNF-alpha with either interferon alpha or gamma . Unlike the effects of interferons, TNF-alpha inhibited the invasiveness of Shigella flexneri and the TNF-alpha effect was not inhibited by cycloheximide.

Mutat Res, 1989 Jan, 210(1), 165 - 72
Modes of genotoxicity of a macromolecular antibiotic, SN-07, a novel type of interstrand DNA cross-linker; Yajima N et al.; The modes of genotoxicity of a novel macromolecular antitumor antibiotic (SN-07) were examined using both prokaryotic and eukaryotic cells in vitro . The antibiotic induced a frameshift-type reverse mutation in Ames Salmonella typhimurium TA98 at 1.6-400 ng/plate with and without S9 mix . SN-07 also induced chromosomal aberrations and a forward mutation (6-TGr) in Chinese hamster V79 cells after 1 h treatment at 12.5-100 ng/ml without metabolic activation . The alkaline elution technique revealed that SN-07 induced interstrand DNA cross-linking dose-dependently after treatment with 2.5-10 micrograms/ml for 1 h followed by elution at pH 12.1, but it did not induce the dose-dependent cross-linking after the same treatment followed by elution at pH 12.6 . It was also found that SN-07 induced single-strand DNA breaks (pH 12.1) and alkali-labile (pH 12.6) sites after treatment with 0.1-10 micrograms/ml for 1 h followed by 24-h post-incubation.

Gene, 1988 Dec 15, 73(1), 201 - 8
Salmonella typhimurium metE operator-constitutive mutations; Plamann LS et al.; We used a metE-lacZ fusion phage (lambda Elac) to select for mutants with operator-constitutive mutations in the Salmonella typhimurium metE control region . All of the mutations identified were found to lie within a region containing tandemly-repeating 8-bp palindromes with the consensus sequence 5'-AGACGTCT-3', previously proposed to be the binding region for the metJ-encoded repressor . Lysogens carrying mutant lambda Elac phage exhibit high beta-galactosidase levels that are only partially repressible by methionine . Although repression of metE expression by vitamin B12 is not disrupted in metJ+ lysogens, vitamin B12 repression is disrupted in lysogens lacking an active MetJ repressor . These results suggest that there is an interaction between the metJ-encoded repressor and the vitamin B12 repression system mediated by the metH gene product.

Gene, 1988 Dec 15, 73(1), 193 - 200
The control region of the metH gene of Salmonella typhimurium LT2: an atypical met promoter; Urbanowski ML et al.; The control region of the Salmonella typhimurium metH gene was sequenced and the transcription start point was determined by S1 nuclease mapping experiments . Activation of the metH gene by the metR gene product was shown to occur at the level of transcription . The translation start site was determined by amino acid sequence analysis of the amino terminus of a chimeric Met-Lac fusion protein encoded by a metH-lacZ gene fusion . Analysis of the nucleotide sequence of the metH promoter region showed that two sequence elements, present in the promoters of all other met biosynthetic genes thus far examined, are not present in the metH promoter region, namely, the repeated MetJ repressor recognition sequence 5'-AGACGTCT-3' and a highly conserved sequence 5'-TGGA----TAAAC-3' of unknown function.

Eur J Biochem, 1988 Dec 15, 178(2), 459 - 64
Isolation of a mutant from Salmonella typhimurium producing acyl-deficient lipopolysaccharides; Lehmann V et al.; The present paper describes the isolation and characterization of a mutant (mutant Ts7) of Salmonella typhimurium that is conditionally defective in the incorporation of dodecanoic and tetradecanoic acid into lipopolysaccharide precursor structures . Enrichment of mutant Ts7 was achieved by free-flow electrophoresis and was based on a previous observation that at least some Salmonella mutants conditionally blocked in the synthesis of the 3-deoxy-D-manno-octulosonic acid (dOc1A)-lipid-A region exhibit higher electrophoretic mobilities than cells with intact dOc1A-lipid-A regions . Under nonpermissive conditions (42 degrees C) mutant Ts7 accumulates at least two incomplete dOc1A-lipid-A structures . One is made up of glucosamine, phosphate, dOc1A, and 3-hydroxytetradecanoic acid in a molar ratio 1.0:1.3:1.0:2.2 and is devoid of dodecanoic and tetradecanoic acid . The other structure has the same basic structure but contains hexadecanoic acid.

J Biol Chem, 1988 Dec 15, 263(35), 18793 - 801
Magnetic resonance and kinetic studies of the partial complex and Component I subunit forms of Salmonella typhimurium anthranilate synthase; Summerfield AE et al.; Metal ion interactions of the monofunctional partial complex of Salmonella typhimurium anthranilate synthase were investigated using kinetic, NMR, and EPR methods . Mn2+ activates AS-partial complex in place of Mg2+, with a Km of 0.08 microM for Mn2+ and of 3.5 microM for Mg2+ in glutamine-dependent anthranilate synthase activity . The kinetics indicated that the metal interacts at the active site with chorismate, not glutamine . EPR and NMR water proton relaxation rate (PRR) studies supported this conclusion . EPR binding analysis showed that chorismate dramatically tightens Mn2+ binding by the partial complex . PRR experiments indicated that stoichiometric amounts of chorismate cause a substantial decrease in the enhancement of water relaxation by Mn2+, while millimolar amounts of glutamine have no effect . Analysis of the frequency dependence of water proton relaxation rates yielded dipolar correlation times of 2.5 x 10(-9) s and 4.1 x 10(-9) s for the Mn2+-partial complex and Mn2+-partial complex-chorismate complexes, respectively . These studies also indicated that chorismate binding reduces the number of fast-exchanging water molecules on enzyme-bound Mn2+ from 1 to 0.25 . PRR experiments with the native bifunctional anthranilate synthase-phosphoribosyltransferase enzyme indicated the existence of additional Mn2+-binding sites which presumably function to activate the phosphoribosyltransferase activity of the Component II subunit.

J Biol Chem, 1988 Dec 5, 263(34), 17917 - 20
Formaldehyde and photoactivatable cross-linking of the periplasmic binding protein to a membrane component of the histidine transport system of Salmonella typhimurium; Prossnitz E et al.; The histidine permease of Salmonella typhimurium consists of four protein components, one located in the periplasm and three in the cytoplasmic membrane . Genetic evidence indicated that the periplasmic protein interacts with the membrane proteins during transport . We have utilized two different methods to demonstrate that the periplasmic protein cross-links specifically to one of the membrane components, the Q protein . Formaldehyde, a water-soluble permeant molecule was used in vivo . Sulfosuccinimidyl 6-(4'-azido-2'-nitrophenylamino)hexanoate, a photoactivatable cross-linking reagent, was used in vitro in a reconstituted membrane vesicle system . Furthermore, we show that a mutant periplasmic protein, capable of binding substrate but not transporting it, is defective in cross-linking to the membrane protein, indicating this interaction to be a crucial step in the mechanism of transport.

Vet Rec, 1988 Dec 3, 123(23), 590 - 4
Aerosol infection of calves and mice with Salmonella typhimurium; Wathes CM et al.; The likelihood of airborne spread and infection by Salmonella typhimurium was studied in calves and mice . S typhimurium survived in air sufficiently long to present a significant hazard of airborne spread . In a dry climate (32 per cent relative humidity) its predicted viability five minutes after aerosolization was 4 per cent relative to its initial value . This increased to 24.8 per cent in a humid atmosphere (72 per cent relative humidity) . Inhalation of S typhimurium by mice caused disease and death at times dependent upon the dose . Even the lowest dose of about 150 colony forming units (cfu) produced disease . Inoculation of approximately 10(4) to 10(6) cfu S typhimurium by either 'mouth and nose only' or 'whole body' aerosol exposure caused infection in calves . The consequences for the control of salmonellosis in intensive calf husbandry are discussed in the light of this demonstration that airborne transmission can be a primary mode of infection of S typhimurium.

Infect Immun, 1988 Dec, 56(12), 3116 - 20
Augmentation of host resistance to microbial infections by recombinant human interleukin-1 alpha; Minami A et al.; Recombinant human interleukin-1 alpha augmented resistance of mice to microbial infections caused by Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus pneumoniae, Salmonella typhimurium, and Candida albicans . The effective doses of interleukin-1 alpha ranged from 0.01 to 10 micrograms per mouse, depending on the infecting organism, route of administration, and challenge dose . Intravenous interleukin-1 alpha was, dose for dose, more effective than intravenous muramyl dipeptide and lentinan against the P . aeruginosa and K . pneumoniae infections . Augmentation by interleukin-1 alpha of resistance to infection was also observed in P . aeruginosa-infected mice in a state of cyclophosphamide-induced leucopenia . Interleukin-1 alpha may be useful for controlling obstinate infections not curable by antimicrobial agents alone.

Cell Biol Toxicol, 1988 Dec, 4(4), 453 - 65
Human hepatocyte and kidney cell metabolism of 2-acetylaminofluorene and comparison to the respective rat cells; Langenbach R et al.; The metabolism and mutagenic activation of 2-acetylaminofluorene by human and rat hepatocytes and kidney cells were measured . High performance liquid chromatography was used to separate the 2-acetylaminofluorene metabolites, and a cell-mediated Salmonella typhimurium mutagenesis assay was used to detect mutagenic intermediates . Rat and human differences were observed with cells from both organs and levels of metabolism and mutagenesis were higher in human cells . Within a species, liver and kidney cell differences were also evident, with levels of hepatocyte-mediated metabolism and mutagenesis being greater than kidney cells . Human inter-individual variation was apparent with cells from both organs, but the variation observed was significantly greater in hepatocytes than kidney cells . A knowledge of such differences, including an understanding that they may vary with the chemical being studied, should be useful in the extrapolation of rodent carcinogenesis data to humans.

J Antibiot (Tokyo), 1988 Dec, 41(12), 1752 - 7
Antibiotics from basidiomycetes . XXIX: Pilatin, a new antibiotically active marasmane derivative from cultures of Flagelloscypha pilatii agerer; Heim J et al.; Pilatin, a new marasmane derivative, was isolated from fermentations of the cyphelloid fungus Flagelloscypha pilatii . Its structure was determined by chemical and physical methods . Pilatin inhibits the growth of bacteria and fungi at concentrations of 5-50 micrograms/ml . The compound is highly cytotoxic . The incorporation of thymidine and uridine into DNA and RNA in Ehrlich carcinoma ascitic cells is strongly inhibited by pilatin . Like marasmic acid pilatin causes frameshift mutations in Salmonella typhimurium TA98.

J Trop Med Hyg, 1988 Dec, 91(6), 315 - 8
Salmonella responsible for infantile gastroenteritis in Mosul, Iraq; al-Rajab WJ et al.; The aetiological role of salmonella in acute diarrhoeal illness in infants aged between 4 weeks and 7 years admitted to the Mosul Paediatric Hospital (North Iraq) was studied . Patients consisted of 63 males and 48 females . Almost all (18) salmonella positive cultures were isolated from patients under 2 years old who comprised 84 (75.6%) of the total sample . A wide variety of species of salmonella were found with Salm . typhimurium and Salm . worthington predominating . Most of the strains were sensitive to chloramphenicol and tetracycline . This study emphasizes the importance of high rates of Salmonella spp . as potential causes of diarrhoeal disease in infancy and childrenPIP: The etiologic role of salmonella in acute diarrheal illness in 111 children 4 weeks-7 years of age admitted to North Iraq's Mosul Pediatric Hospital was investigated . 75% of all children with diarrhea were under 2 years of age; 29% of them were under 6 months and 45% were under 18 months . 57% of the children were male; 43% were female . Rectal swab analysis revealed a high rate of isolation of salmonella serotypes in this random sample--17 children (15%) . Salmonella typhimurium and worthington predominated . 72% of the salmonella strains were sensitive to chloramphenicol and 61% were responsive to tetracycline . The majority of salmonella-positive cultures were isolated from children under 1 year of age . Only 1 child who was solely breastfed was infected with salmonella, confirming the protective role of this infant feeding practice . Since 45% of the children in this study with negative stool cultures for salmonella had been treated for diarrhea and vomiting before admission, it is likely that the rate of salmonella infection in the sample is an underestimate of its true prevalence in this population .

Carcinogenesis, 1988 Dec, 9(12), 2305 - 8
Synthesis and mutagenicity of 5-alkyl-substituted chrysene-1,2-diol-3,4-epoxides; Amin S et al.; In order to explore the relationship between structure and mutagenicity of bay region diol-epoxides of chrysene substituted with an alkyl group in the bay region, we compared the mutagenicity in Salmonella typhimurium TA 100 of anti-1,2-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydrochrysene with its 5-methyl, 5-ethyl and 5-propyl derivatives . The results showed that anti-1,2-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydro-5-methylchrysene (7400 revertants/nmol) was the most mutagenic of these diol-epoxides followed by anti-1,2-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydrochrysene and its 5-ethyl derivative (1100 revertants/nmol) . The 5-propyl substituted diol-epoxide was inactive at the doses tested . The results demonstrate that steric factors are dominant in the expression of methylchrysene diol-epoxide mutagenicity in S . typhimurium and suggest that the molecular shape of the 5-methyl substituted diol-epoxide leads to a unique reaction with DNA associated with high mutagenicity and tumorigenicity.

Carcinogenesis, 1988 Dec, 9(12), 2291 - 5
Metabolic activation of cyclopenteno{c,d}pyrene by peroxyl radicals; Reed GA et al.; The conversion of cyclopento{c,d}pyrene (CPP) to forms which are mutagenic to Salmonella typhimurium strain TA98 has been demonstrated in systems which generate peroxyl radicals . The systems examined included prostaglandin H synthase (PHS) and arachidonic acid, 15-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE) and hematin, and the autoxidation of the sulfite ion . In all cases concentration-dependent activation of CPP was observed at hydrocarbon concentrations between 10 and 100 microM . Neither CPP nor the peroxyl radical systems alone were mutagenic or toxic to the tester strain . The use of hydroxygen peroxide with PHS, a peroxidative system which does not yield peroxyl radicals, does not activate CPP . The involvement of a CPP epoxide was examined using 1,1,1-trichloropropene-2,3-oxide . Addition of this epoxide hydrolase inhibitor to incubations of CPP with the PHS/arachidonic acid system resulted in a 210% increase in induced revertants relative to the system in the absence of the inhibitor . The addition of pure rat liver microsomal epoxide hydrolase to incubations of CPP with the 15-HPETE/hematin system resulted in a concentration-dependent loss of mutagenicity, further supporting the intermediacy of an epoxide . The site of metabolism of CPP is the cyclopenteno double bond based on the formation of products which display distinct pyrene-type fluorescence spectra . The involvement of the cyclopenteno double bond also is shown by the inability of the 15-HPETE/hematin system to activate 3,4-dihydrocyclopenteno{c,d}pyrene as a mutagen . CPP is the first environmentally-relevant carcinogenic hydrocarbon found to be activated directly by peroxyl radical systems without prior biotransformation to a diol derivative by the cytochrome P-450 system . These findings expand the range of potentially toxic substrates to be considered for activation by peroxyl radical pathways.

Jpn J Cancer Res, 1988 Dec, 79(12), 1284 - 92
Augmenting effect of a nonmutagenic fraction in soy sauce on mutagenicity of 3-diazotyramine produced in the nitrite-treated sauce; Higashimoto M et al.; When 25 kinds of Japanese soy sauce at a concentration of 5% were incubated with 50mM sodium nitrite (pH 2) at 37 degrees for 1 hr, the reaction mixtures induced 34-834 (average 368 +/- 228) revertants per microliter of soy sauce equivalent in Salmonella typhimurium strain TA100 in the absence of S9 mix . The mutagen(s) formed was very unstable under natural daylight and a fluorescent lamp but quite stable under a yellow lamp as well as in the dark . In addition to the known precursors, i.e., tyramine and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid, 1-methyl-1,2,3,4-tetrahydro-beta-carboline, which caused weak mutagenesis, was found in the soy sauce . However, the sum of the activities of the three mutagen-precursors after nitrite treatment accounted for only a part of the mutagenicity of nitrite-treated soy sauce . There was in the soy sauce a factor which increased ninefold the mutagenicity of nitrite-treated tyramine, 3-diazotyramine . Therefore, tyramine was considered the principal precursor of the mutagen produced in the nitrite-treated soy sauce . These three precursors together with the mutagenicity augmentation accounted for all the mutagenicity of nitrite-treated sauce . The mutagenicity-augmenting factor in the soy sauce was nonmutagenic before and after nitrite treatment and was stable to heat and light irradiation.

FEMS Microbiol Immunol, 1988 Dec, 1(3), 133 - 8
Studies on the hexose region of the lipopolysaccharide from a low virulence strain of Salmonella typhimurium; dalla Venezia N et al.; The structure of the hexose region of the lipopolysaccharide from M206 strain, a mutant of Salmonella typhimurium having reduced virulence, was partially determined . Immunological tests indicated cross-reactions of anti-(M206) antiserum with wild-type C5 and Ra mutant strains . Data obtained on chemical composition, periodate oxidation, acetolysis, methylation and analysis by gas chromatography/mass spectrometry show that M206 type lipopolysaccharide contains the common core polysaccharide of Salmonella which was substituted in position 4 of the subterminal glucose unit by a disaccharide: D-glucosyl 1----3 D-galactose . This substitution is probably related to the slight virulence of M206 strain.

Mol Gen Genet, 1988 Dec, 215(1), 107 - 17
Regulation of a transport operon promoter in Salmonella typhimurium: identification of sites essential for nitrogen regulation; Schmitz G et al.; The promoter of nitrogen-regulated transport, argtr, has been mutationally altered in order to determine the features that are essential for its response to nitrogen availability . Deletions of all sequences upstream of position -44 or downstream of position +2 had no effect on nitrogen regulation of argTr . These deletions define a small region of 44 bp where all necessary features for nitrogen regulation are located . This region includes sequences highly homologous to the nif consensus promoter . Alteration of this particular sequence caused drastic changes in the response to changes of nitrogen availability, thus indicating that they are directly involved in regulation . This implies that the NtrC protein must also act within this small region of the promoter . The data are discussed in terms of current-hypotheses concerning nitrogen regulation . In addition, we have shown 1 . that carbon regulation at this promoter must occur at a site upstream from the nitrogen promoter; 2 . that nifA can replace ntrC in the regulation of argTr.

Mutat Res, 1988 Dec, 206(4), 467 - 70
Absence of mutagenic activity of acidity regulators in the Ames Salmonella/microsome test; Al-Ani FY et al.; The activities of various concentrations of 4 acidity regulators (anhydrous citric acid, phosphoric acid, malic acid and lactic acid) used in food industries in Iraq was assayed using the Salmonella/microsome mutagenicity assay . None of the samples was mutagenic in the absence or in the presence of S9 to any of the tester strains of Salmonella typhimurium.

Mutat Res, 1988 Dec, 206(4), 459 - 65
Influence of glutathione on the mutagenicity of 2-chloroethylnitrosoureas . Mutagenic potential of glutathione derivatives formed from 2-chloroethylnitrosoureas and glutathione; Stahl W et al.; 2-Chloroethylnitrosoureas (CNU) are antineoplastic agents whose therapeutic dose is limited by toxic and carcinogenic side effect . The clinically used drugs, bis-(2-chloroethyl)nitrosourea (BCNU) and 1-(2-chloroethyl)-3-(2-hydroxyethyl)-1-nitrosourea (HECNU) and their analogue N-(2-chloroethyl)-N-nitrosocarbamoyl-glycinamide (CNC-GA) were tested for mutagenicity and toxicity in the Salmonella typhimurium tester strain TA1535 in the presence and absence of glutathione (GSH) . All 3 compounds proved to be potent mutagens . The cytotoxicity of these CNUs, however, varied depending on their carbamoylating activity . These cytotoxic effects were decreased considerably by the addition of GSH . It has been shown that the isocyanate decomposition product of the 2-chloroethylnitrosoureas reacts with GSH yielding S-carbamoylated GSH derivatives . The adducts resulting from coincubation of BCNU or HECNU with GSH, 2-chloroethyl-S-carbamoyl-GSH and 2-hydroxy-S-carbamoyl-GSH, were also tested for their mutagenic activity . While the hydroxyethylated compound exhibited no effects, 2-chloroethyl-S-carbamoyl-GSH and its cysteine analogue, 2-chloroethyl-S-carbamoyl-GSH, were strong mutagens . Further experiments with 3-chloropropyl-S-carbamoyl-GSH and t-butyl-S-carbamoyl-GSH indicate that a chlorine substituent in the beta position is necessary for the induction of a potent mutagenic response.

Mutat Res, 1988 Dec, 206(4), 447 - 54
Evaluation of the mutagenic and cytostatic potential of aristolochic acid (3,4-methylenedioxy-8-methoxy-10-nitrophenanthrene-1-carboxylic acid) and several of its derivatives; Pezzuto JM et al.; Aristolochic acid (1), a constituent of Aristolochia species, has been used for medicinal purposes since the Graeco-Roman period . Following the observation that the compound was mutagenic and carcinogenic, it was removed from pharmaceutical products . Consistent with previous reports, we have found that 1 serves as a direct-acting mutagen in Salmonella typhimurium strains TA100, TA102, TA1537 and TM677, but was not active in the nitroreductase-deficient strains TA98NR and TA100NR . However, aristolic acid (2), a compound that differs in structure only by the absence of the nitro group, was also found to be a direct-acting mutagen in Salmonella strains TA98, TA100, TA102, TA1537, and TM677, as well as strains TA98NR and TA100NR . Both compounds (1 and 2) were active mutagens when evaluated with cultured Chinese hamster ovary cells . Thus, in contrast to previous suggestions, the nitro group at position 10 is not required to induce a mutagenic response . Also, a series of structural relatives (the methyl esters of 1 and 2 (3 and 4, respectively), aristolochic acid-D (5), aristolactam (6), aristolactam A-II (7), and aristolactam-N-beta-D-glucoside (8)) were evaluated for mutagenic potential with Salmonella typhimurium strain TM677 and found to be inactive . Since compounds 3 and 4 were found to be active mutagens with Salmonella typhimurium strains TA98, TA100, TA102 and TA1537 (sufficient quantities of compounds 5-8 were not available for testing), differential sensitivity of the tester strains unrelated to mutagenic potential is suggested . Further, compounds 1, 2, and 6-8 were evaluated for potential to inhibit growth with cultured KB or P388 cells . P388 cells were substantially more sensitive, and compound 1 was the most active of the materials tested (ED5 = 0.58 microM) . Compound 6 also demonstrated appreciable activity (ED50 = 4.2 microM), as did compound 8 (ED50 = 6.0 microM) . It therefore appears that phenanthrene-ring substituents, in addition to the nitro group at position 10, serve important roles for biological potential . In considering the carcinogenic event induced by aristolochic acid, these functionalities should also be taken into account.

Biochem Pharmacol, 1988 Dec 1, 37(23), 4505 - 12
Environment-selective synergism using self-assembling cytotoxic and antimicrobial agents; Rideout D et al.; Environment-selective synergistic toxicity using combinations of aldehydes and hydrazine derivatives was demonstrated in two different model systems in vitro . Combinations of 5-nitro-2-furaldehyde with semi-carbazide and of 2-hydrazinopyridine with pyridine-2-carboxaldehyde, which can react in situ to form antimicrobial hydrazones, demonstrated greater degrees of synergism against the intracellular pathogen, Salmonella typhimurium, at pH 5 relative to pH 7.4 . Combinations are more selectively toxic at pH 5 (vs pH 7.4) than individual precursors and preformed hydrazone products because acid catalysis of hydrazone formation plays a role only for the combinations . A combination of decanal and N-amino, N'-octylguanidine (AOG) exhibited more pronounced synergistic cytolytic activity against erythrocytes in 0% serum than in 1% serum . Serum protein binding of decanal inhibited the formation of the more cytotoxic hydrazone, N-decylidenimino,N'-1-octylguanidine (DIOG), from the less cytotoxic AOG and decanal, and serum protein binding of DIOG prevented this cytotoxin from reaching the cell membrane . Because decanal binding cannot play a role in the cytotoxicity of preformed DIOG, it was less selective for cells in 0% serum than the combination of AOG and decanal . The pH 5 and 0% serum environments represent very simple models for macrophage phagolysosomal compartments and poorly vascularized solid tumor interiors respectively . If environment-selective synergism can be used as a basis for target-selective synergism in other in vitro model systems and in vivo, self-assembling combinations could provide a basis for rational introduction of target-selective synergism into chemotherapeutic drug design.

J Med Microbiol, 1988 Dec, 27(4), 277 - 84
Molecular divergence of the serotype-specific plasmid (pSLT) among strains of Salmonella typhimurium of human and veterinary origin and comparison of pSLT with the serotype specific plasmids of S . enteritidis and S . dublin; Platt DJ et al.; Molecular variants of the serotype-specific plasmid (SSP) of Salmonella typhimurium (pSLT) were recognised in clinical and veterinary isolates by restriction enzyme fingerprinting . Three had undergone minor DNA rearrangements, whereas two had acquired resistance determinants to a wide range of antimicrobial agents including gentamicin, trimethoprim, tetracycline, streptomycin, ampicillin (Ap) and kanamycin (Km) . One of the latter was the result of co-integrate formation with an IncX, conjugative R-plasmid that specified ApKm resistance . The co-integrate plasmid (pOG669) was incompatible with, and displaced, pSLT and its molecular variants . The restriction fingerprints of SSPs of S . enteritidis and S . dublin were compared with pSLT . All were related at the 35% level on the basis of a Dice coefficient of similarity . The SSPs of S . enteritidis and S . dublin were incompatible with the co-integrate plasmid pOG669 . Whereas in S . enteritidis this resulted from incompatibility with the pSLT component (the SSP was compatible with the IncX component), the converse was found with S . dublin.

J Infect Dis, 1988 Dec, 158(6), 1329 - 35
Construction and characterization of vaccine strains of Salmonella harboring mutations in two different aro genes; Dougan G et al.; Derivatives of the mouse-virulent Salmonella typhimurium strain SL1344 were constructed harboring stable mutations in aroC alone or in aroC and aroA together . Fifty percent lethal doses after intravenous inoculation of the mutants into BALB/c mice were determined, and the mutants were as highly attenuated as were SL1344 aroA derivatives . All aro-dependent derivatives persisted in vivo at similar levels and for similar intervals in the livers and spleens of BALB/c mice infected intravenously . Mice vaccinated orally with 10(10) live organisms of the different derivatives survived and were well protected against oral challenge with virulent S . typhimurium . A Salmonella typhi Ty2 derivative, designated WBL2000, was constructed that harbors well-defined, stable mutations in both aroA and aroC.

J Bacteriol, 1988 Dec, 170(12), 5751 - 8
Primary structure and mapping of the hupA gene of Salmonella typhimurium; Higgins NP et al.; In bacteria, the complex nucleoid structure is folded and maintained by negative superhelical tension and a set of type II DNA-binding proteins, also called histonelike proteins . The most abundant type II DNA-binding protein is HU . Southern blot analysis showed that Salmonella typhimurium contained two HU genes that corresponded to Escherichia coli genes hupA (encoding HU-2 protein) and hupB (encoding HU-1) . Salmonella hupA was cloned, and the nucleotide sequence of the gene was determined . Comparison of hupA of E . coli and S . typhimurium revealed that the HU-2 proteins were identical and that there was high conservation of nucleotide sequences outside the coding frames of the genes . A 300-member genomic library of S . typhimurium was constructed by using random transposition of MudP, a specialized chimeric P22-Mu phage that packages chromosomal DNA unidirectionally from its insertion point . Oligonucleotide hybridization against the library identified one MudP insertion that lies within 28 kilobases of hupA; the MudP was 12% linked to purH at 90.5 min on the standard map . Plasmids expressing HU-2 had a surprising phenotype; they caused growth arrest when they were introduced into E . coli strains bearing a himA or hip mutation . These results suggest that IHF and HU have interactive roles in bacteria.

J Bacteriol, 1988 Dec, 170(12), 5507 - 11
Signal transduction in chemotaxis to oxygen in Escherichia coli and Salmonella typhimurium; Shioi J et al.; Pathways previously proposed for sensory transduction in chemotaxis to oxygen (aerotaxis) involved either (i) cytochrome o, the electron transport system, and proton motive force or (ii) enzyme IIGlucose and the phosphoenolpyruvate:carbohydrate phosphotransferase system for active transport . This investigation distinguished between these possibilities . Aerotaxis was absent in a cyo cyd strain of Escherichia coli that lacked both cytochrome o and cytochrome d, which are the terminal oxidases for the branched electron transport system in E . coli . Aerotaxis, measured by either a spatial or temporal assay, was normal in E . coli strains that had a cyo+ or cyd+ gene or both . The membrane potential of all oxidase-positive strains was approximately -170 mV in aerated medium at pH 7.5 . Behavioral responses to changes in oxygen concentration correlated with changes in proton motive force . Aerotaxis was normal in ptsG and ptsI strains that lack enzyme IIGlucose and enzyme I, respectively, and are deficient in the phosphotransferase system . A cya strain that is deficient in adenylate cyclase also had normal aerotaxis . We concluded that aerotaxis was mediated by the electron transport system and that either the cytochrome d or the cytochrome o branch of the pathway could mediate aerotaxis.

Diabetes, 1988 Dec, 37(12), 1684 - 8
Myocardial insulin resistance during acute endotoxin shock in dogs; Raymond RM et al.; Myocardial insulin responsiveness was determined in open-chest pentobarbital sodium-anesthetized dogs before and after endotoxin administration . Animals were instrumented to measure mean arterial blood pressure (MABP), heart rate (HR), and coronary blood flow . Myocardial glucose uptake and myocardial oxygen uptake (MVO2) were determined during a basal control period and after a hyperinsulinemic-euglycemic clamp procedure over a wide range of insulin concentrations . The clamp was accomplished by intravenously infusing insulin (0-4000 mU/min) and 20% glucose in sufficient amounts to maintain arterial glucose concentrations within 5 mg/dl of the control value . In a separate series of experiments, myocardial insulin responsiveness was determined by use of a single dose of insulin (4000 mU/min) . This was done to determine whether antecedent insulin infusions during the sequential clamp procedure would affect the responsiveness of the heart . In control experiments, myocardial glucose uptake increased without any changes in HR, MVO2, or MABP . Maximum myocardial glucose uptake occurred at an insulin infusion rate between 400 and 4000 mU/min . A single concentration of insulin resulted in similar increases in myocardial glucose uptake as with the sequential clamp protocol . Acute endotoxin shock was induced by bolus injection of 1 mg/kg Salmonella typhimurium endotoxin (Difco Labs, Detroit, MI) . One hour after administration of endotoxin, basal myocardial glucose uptake was decreased compared with the control animals . After 1 h of endotoxin shock, the heart was refractory to all concentrations of insulin, suggesting the site for altered insulin response was being mediated by a postreceptor mechanism.

Microb Pathog, 1988 Dec, 5(6), 407 - 18
A chromosomal integration system for stabilization of heterologous genes in Salmonella based vaccine strains; Hone D et al.; We have developed a system whereby heterologous DNA encoding an antigen from an enteropathogen may be recombined into the chromosome of an attenuated Salmonella carrier strain . The system involves two steps: (i) integration of a hisOG deletion mutation into the chromosome; (ii) replacement of the hisOG deletion by the complete hisOG region and the segment of heterologous DNA which encodes the antigen of interest . Recombinants may be selected (his+) . The system was used to integrate the genes encoding K88 fimbriae from enterotoxigenic Escherichia coli into the chromosome of a galE mutant of Salmonella typhimurium (LT2H1) . Recombinants were detected at a frequency of between 1.0 x 10(-3) and 1.5 x 10(-3) . A variety of tests confirmed that the K88 genes were integrated into the chromosome of LT2H1 and were expressed . The stability of the recombinant was tested both in vivo and in vitro . When administered orally to mice, the recombinant elicited a serum antibody response to K88, and retained the Salmonella vaccine potential of the vector strain.

J Biochem (Tokyo), 1988 Dec, 104(6), 917 - 23
Glutamine synthetase from a cyanobacterium, Phormidium lapideum: purification, characterization, and comparison with other cyanobacterial enzymes; Sawa Y et al.; Glutamine synthetase has been purified to homogeneity from cell extracts of a non-N2-fixing filamentous cyanobacterium, Phormidium lapideum . The subunit molecular weight of the enzyme was determined as about 59,000 by sodium dodecyl sulfate gel electrophoresis . Electron micrographs of the Phormidium enzyme revealed a two-layered structure of regular hexagons (12 subunits per molecule), which markedly resembles the three-dimensional polypeptide backbone structure of the Salmonella typhimurium glutamine synthetase established by X-ray crystallography (Almassy, Janson, Hamlin, Xuong, & Eisenberg (1986) Nature 323, 304-309) . The N-terminal amino acid sequence of the Phormidium enzyme shows very high similarity with that of the enzyme from an N2-fixing cyanobacterium, Anabaena 7120; 18 residues are common in 23 residues compared . Strong immunocross-reactions between the antibody against the purified Phormidium glutamine synthetase and other cyanobacterial enzymes except the Anacystis enzyme were observed . The apparent Michaelis constants for NH3, L-glutamate, and ATP were determined to be 0.29, 7.4, and 1.7 mM, respectively . Divalent metal ions such as Mg2+ and Mn2+ activated the enzyme in the biosynthetic reaction, whereas various amino acids and glutamate analogs strongly inhibited the enzyme.

Infect Immun, 1988 Dec, 56(12), 3262 - 71
Cloning and transposon insertion mutagenesis of virulence genes of the 100-kilobase plasmid of Salmonella typhimurium; Gulig PA et al.; We have cloned regions of the 100-kilobase (kb) plasmid, pStSR100, of Salmonella typhimurium SR-11 that confer virulence to plasmid-cured S . typhimurium . Cells carrying recombinant plasmids that conferred virulence were selected by inoculating mice orally with recombinant libraries in virulence plasmid-cured S . typhimurium and harvesting isolates that infected spleens . Three plasmids, pYA401, pYA402, and pYA403, constructed with the cosmid vector pCVD305 conferred wild-type levels of virulence to plasmid-cured S . typhimurium and had a common 14-kb DNA insert sequence . Another recombinant plasmid, pYA422, constructed with the vector pACYC184, conferred to plasmid-cured S . typhimurium a wild-type 50% lethal dose (LD50) level, but mice died more slowly than when infected with wild-type S . typhimurium . Furthermore, pYA422 conferred the ability to cause a higher, but not a wild-type, level of splenic infection on plasmid-cured S . typhimurium . pYA422 had a 3.2-kb insert sequence which mapped to the center of the 14-kb common sequence of the cosmid clones . Transposon Tn5 insertion mutations in pYA403 inhibited virulence to various degrees, and when transduced into the native virulence plasmid of S . typhimurium, these Tn5 insertions decreased virulence to degrees similar to those observed when the Tn5 insertions were present in pYA403 . vir-22::Tn5 in pStSR100 greatly lowered infection of spleens relative to unmutagenized virulence plasmid, while vir-26::Tn5 and vir-27::Tn5 lowered splenic infection to lesser degrees . At least three proteins were encoded by pYA403 containing 23 kb of insert sequence and subclone pYA420, containing the 14-kb common insert sequence present in all of the cosmid clones . One of these proteins, with an apparent molecular weight of 28,000, was also encoded by pYA422 . The Tn5 insertion that most attenuated virulence, vir-22::Tn5, inhibited synthesis of the 28,000-molecular-weight protein . The vir-22::Tn5 insertion was complemented by recombinant plasmids encoding only the 28,000-molecular-weight protein, suggesting a role of this protein in virulence . However, recombinant plasmids, exemplified by pYA422, that encoded only the 28,000-molecular-weight protein did not confer full virulence.

Arch Int Physiol Biochim, 1988 Dec, 96(5), 171 - 7
Peptidoglycan hydrolases in an autolytic mutant of Salmonella typhimurium; Pizarro RA et al.; Two peptidoglycan hydrolases were isolated from the autolytic mutant Salmonella typhimurium DA361 (envD) . One of them, resistant to penicillin, was found free in the supernatant of partially purified envelopes sedimented by ultracentrifugation, and the other bound to the envelopes proved to be sensitive to the antibiotic . Both were able to hydrolyse in vitro high molecular weight non-specific peptidoglycan isolated from E . coli W7 labelled with {14C}diaminopimelic acid . Similar enzymatic activities were separated also from S . typhimurium DA362 (envD+) a non-lytic isogenic pair of the above and from the wild type strain LT-2 . All of the hydrolytic activities reported here were strongly inhibited when DNA was added to the assay systems . The peptidoglycan hydrolases isolated from the autolytic mutant suffered a competitive inhibition while those from the non-lytic strains were apparently inhibited in uncompetitive modal relationship . It is postulated that the inhibitory effect may bear affinity with the preservation of DNA sites of attachment to cell membranes sustaining peptidoglycan structure and functions.

Antimicrob Agents Chemother, 1988 Dec, 32(12), 1763 - 8
In vitro mechanism of inhibition of bacterial cell growth by allicin; Feldberg RS et al.; Diallyl thiosulfinate (allicin) is the agent found in garlic which is responsible for the antibacterial and antifungal activity of extracts of this plant . The effect of bacteriostatic concentrations of allicin (0.2 to 0.5 mM) on the growth of Salmonella typhimurium revealed a pattern of inhibition characterized by: (i) a lag of approximately 15 min between addition of allicin and onset of inhibition, (ii) a transitory inhibition phase whose duration was proportional to allicin concentration and inversely proportional to culture density, (iii) a resumed growth phase which showed a lower rate of growth than in uninhibited controls, and (iv) an entry into stationary phase at a lower culture density . Whereas DNA and protein syntheses showed a delayed and partial inhibition by allicin, inhibition of RNA synthesis was immediate and total, suggesting that this is the primary target of allicin action.

J Biol Chem, 1988 Nov 25, 263(33), 17857 - 71
Three-dimensional structure of the tryptophan synthase alpha 2 beta 2 multienzyme complex from Salmonella typhimurium; Hyde CC et al.; The three-dimensional structure of the alpha 2 beta 2 complex of tryptophan synthase from Salmonella typhimurium has been determined by x-ray crystallography at 2.5 A resolution . The four polypeptide chains are arranged nearly linearly in an alpha beta beta alpha order forming a complex 150 A long . The overall polypeptide fold of the smaller alpha subunit, which cleaves indole glycerol phosphate, is that of an 8-fold alpha/beta barrel . The alpha subunit active site has been located by difference Fourier analysis of the binding of indole propanol phosphate, a competitive inhibitor of the alpha subunit and a close structural analog of the natural substrate . The larger pyridoxal phosphate-dependent beta subunit contains two domains of nearly equal size, folded into similar helix/sheet/helix structures . The binding site for the coenzyme pyridoxal phosphate lies deep within the interface between the two beta subunit domains . The active sites of neighboring alpha and beta subunits are separated by a distance of about 25 A . A tunnel with a diameter matching that of the intermediate substrate indole connects these active sites . The tunnel is believed to facilitate the diffusion of indole from its point of production in the alpha subunit active site to the site of tryptophan synthesis in the beta active site and thereby prevent its escape to the solvent during catalysis.

Vet Rec, 1988 Nov 19, 123(21), 536 - 41
Passive protection of calves against experimental infection with Salmonella typhimurium; Jones PW et al.; Cows were vaccinated with formalin-killed Salmonella typhimurium approximately seven weeks and two weeks before parturition to investigate whether passive immunity could protect their calves against experimental S typhimurium infection . After birth the calves were left with their dam for 48 hours and then separated and fed cold, stored colostrum from their own dam for a further eight days . Oral challenge five days after birth with 10(8) S typhimurium did not result in the death of these calves even when they had absorbed little colostrum . Mortality was reduced to 22 per cent in calves which sucked from vaccinated dams and were then fed colostrum from unvaccinated cows and to 50 per cent in calves born to unvaccinated cows and later fed colostrum from vaccinated animals . Calves which sucked from a vaccinated dam and then received stored colostrum from the same cow excreted salmonellas for significantly shorter periods after challenge and were less often infected at necropsy 28 days after inoculation . Protection was not correlated with the levels of O or H agglutinating antibodies in serum, which were at a maximum 24 hours after sucking and then slowly declined . There was no evidence of an active antibody response in the serum . Measurement of the O and H response of cows after vaccination indicated that the vaccination schedule could be improved . The highest levels of agglutinating antibody were measured between two and three weeks after the first vaccination and there was only a minimal response to the second vaccination before parturition.(ABSTRACT TRUNCATED AT 250 WORDS)

Anal Biochem, 1988 Nov 15, 175(1), 52 - 8
Real time computer tracking of free-swimming and tethered rotating cells; Poole PS et al.; A computerized image processing system has been developed that tracks individual free-swimming cells and rotating bacterial cell bodies tethered by their flagella in real time . Free-swimming bacteria of Rhodobacter sphaeroides, Rhodospirullum rubrum, and Salmonella typhimurium have been tracked swimming at speeds from 0 to over 120 microns s-1 . A high level of discrimination is exerted against noncellular objects, allowing analysis of stopped as well as moving cells . This enabled detection of both speed and qualitative change in the swimming patterns of R . sphaeroides WS8 upon tactic stimulation . Comparison with darkfield microscopy indicated that the two techniques were in substantial agreement . The unidirectional rotation of cells of R . sphaeroides WS8 could be detected when the cells were either parallel to the microscope slide or end on . Frequencies of rotation of up to 10 Hz were monitored before image blurring became a problem . True rods would be easier to analyze at higher speeds of rotation . Although developed for photosynthetic bacteria, a wide range of bacteria, eucaryotic organisms, and subcellular organelles could be tracked with this system . Minor modifications to the software allow customization to different types of motility analysis.

J Nat Prod, 1988 Nov-Dec, 51(6), 1166 - 72
Polypodoside A, an intensely sweet constituent of the rhizomes of Polypodium glycyrrhiza; Kim J et al.; Polypodoside A, a novel intensely sweet constituent of the rhizomes of Polypodium glycyrrhiza, was established by spectral and chemical methods as 26-O-alpha-L-rhamnopyranosyl-polypodogenin-3-O-alpha-L-rhamnopyran osyl- (1----2)-beta-D-glucopyranoside {1} . At the doses tested, this isolate was not acutely toxic for mice and was nonmutagenic with Salmonella typhimurium strain TM677 . This compound was rated by a human taste panel as exhibiting 600 times the sweetness intensity of a 6% w/v aqueous sucrose solution.

J Pharm Sci, 1988 Nov, 77(11), 955 - 8
Potential metabolic mutagens of caffeine and various methylxanthines; Lander N et al.; Xanthine N-carbinols, potential metabolites of caffeine and other methylxanthines, have been synthesized, characterized, and derivatized . Such intermediates, the initial metabolites arising from the cytochrome P-450 oxidation of the nitrogen-bound methyl groups, may be viewed as biological N-carbinols capable of alkylating proteins and nucleic acids . Evaluation of these compounds against Salmonella typhimurium, strain TA100, has demonstrated that, in contrast to caffeine, 7-hydroxymethyltheophylline and the 3,7-bis(hydroxymethyl)-1-methylxanthine mixture did exhibit cytotoxicity . There was no evidence of mutagenesis and it is possible that the Ames assay system is not applicable to N-carbinols.

J Antimicrob Chemother, 1988 Nov, 22(5), 675 - 86
Enhanced susceptibility of gram-negative bacteria to phagocytic killing by human polymorphonuclear leucocytes after brief exposure to aztreonam; Pruul H et al.; Brief exposure of Escherichia coli, Serratia marcescens, Klebsiella pneumoniae and Salmonella typhimurium to supra-inhibitory concentrations of aztreonam enhanced their susceptibility to phagocytic killing by human polymorphonuclear leucocytes . The effect was independent of the continuous presence of the antibiotic and required the presence of serum opsonins . Phagocytic killing of Pseudomonas aeruginosa was enhanced by prior exposure to subminimal inhibitory concentrations, and killing, relative to control bacteria, was not increased with increasing concentrations of aztreonam above minimal inhibitory concentrations . The degree of sensitization, and the range of bacteria susceptible to antibiotic modulation varied between antibiotics . Under the conditions of these experiments, gentamicin sensitized pseudomonas, but failed to sensitize E . coli, while cefotaxime failed to sensitize serratia, and varied in it's activity against E . coli and pseudomonas . Enhanced killing of aztreonam-pretreated bacteria was associated with an increase in uptake by leucocytes . Aztreonam exposure decreased the liability of the bacteria to hydrophilic interactions in an aqueous two-phase partitioning system . These observations indicate that exposure of Gram-negative bacteria to aztreonam enhances phagocytic killing through modification of cell surface structures . This may be mediated through an increase in surface hydrophobicity which enhances bacterial association with leucocyte membranes with subsequent phagocytosis and intracellular killing.

Food Chem Toxicol, 1988 Nov-Dec, 26(11-12), 947 - 54
Formation of mutagenic N-nitroso compounds in vegetable extracts upon nitrite treatment: a comparison with the glucosinolate content; Tiedink HG et al.; More than 30 vegetables were screened for their potential to form biologically active N-nitroso compounds upon treatment with nitrite under acidic conditions . The total N-nitroso content was determined in the nitrite-treated and untreated extracts of the vegetables according to a modified method of Walters et al . (Analyst, Lond . 1978, 103, 1127) . All treated extracts contained N-nitroso compounds at levels ranging from 23 to 789 nmol/25 mg dry matter . In the same samples the mutagenic activity was determined using the Salmonella typhimurium assay . About half of the vegetables were found to be mutagenic upon nitrite treatment . (Nitrite-treated extracts were considered to be mutagenic if the number of induced revertants was at least twice as high as that induced by the corresponding untreated extract) . The content of different glucosinolates in the dry matter of the vegetables was also determined . Glucosinolates could be detected only in cruciferous vegetables, at levels ranging from 1.8 to 26.0 mumol/g dry matter . Although the nitrite-treated extracts of brassica species contained more N-nitroso compounds and induced more revertants than did other vegetables, there was no significant correlation between these parameters . However, the amounts of N-nitroso compounds formed upon nitrite treatment (expressed per fresh weight) did correlate significantly (P less than 0.01) with the amounts of glucosinolates (r = 0.95) . When the glucosinolates were divided into aryl/alkyl- and indolyl-glucosinolates, the significant correlation was maintained for both subgroups (r = 0.93 and 0.95, respectively) . From this it can be concluded that glucosinolates are probably involved in the formation of N-nitroso compounds in certain nitrite-treated vegetables.

Food Chem Toxicol, 1988 Nov-Dec, 26(11-12), 883 - 91
Effects of human diets on biotransformation enzyme activity and metabolic activation of carcinogens in rat liver; Alink GM et al.; We studied the effects of a complete human diet, based on mean consumption figures in The Netherlands, the heating of food, and the presence of vegetables and fruit in the diet on the drug metabolizing capacity of the rat liver and on metabolic activation of known carcinogens . Groups of five male and five female Wistar rats were given ad lib . one of six different diets for 3 months . Each diet contained 40 energy (E)% fat, 13 E% protein, 47 E% carbohydrate and 5% fibre (w/w) . The diets were as follows: a control diet of semi-synthetic materials (A); a human diet of meat, bread and eggs without processing (B); diet B heated under usual household conditions (C); a diet representing a complete human meal including (summer) vegetables and fruit (D); diets consisting of winter vegetables (E) or summer vegetables (F) with fruit . Semi-synthetic components were added to diets B-F to achieve the desired composition . There were differences between male and female rats on the effects of the different diets on hepatic enzyme activity . In female rats, but not in males, ethoxyresorufin-O-deethylase activity was increased significantly (P less than 0.05) in groups C, D and E in comparison with the controls (group A) . In male rats ethoxycoumarin-O-deethylase activity was enhanced in groups D, E and F, and glutathione-S-transferase was markedly induced in group F (P less than 0.01) . In males, hepatic cytochrome P-450 was significantly (P less than 0.05) increased in groups B, C and E . There was no effect on aminopyrine-N-demethylase activity and almost no effect on UDP-glucuronyltransferase activity in either sex . Microsomes from rats fed heated food (C) markedly increased the mutagenicity of benzo{a}pyrene (B{a}P) in the Ames assay using Salmonella typhimurium strain TA98, in comparison with levels using microsomes from rats fed the raw food (B) . Vegetables and fruit decreased B{a}P mutagenicity . All human diets except D decreased the mutagenicity of N-nitrosodimethylamine in tester strain TA100 . The results indicate that the influence of components of human diets on rat-liver drug metabolism may have quite different effects on the biotransformation of carcinogens activated by different metabolic pathways.

Arthritis Rheum, 1988 Nov, 31(11), 1377 - 83
Postdysenteric reactive arthritis . A clinical and immunogenetic study following an outbreak of salmonellosis; Inman RD et al.; Following an outbreak of foodborne gastroenteritis caused by Salmonella typhimurium, questionnaires were sent to affected individuals and then to the family physicians of any who experienced extra-enteric complications . Of 260 individuals infected with S typhimurium for whom adequate data were obtained, 19 patients developed joint disease (7.3%) . All were men; the mean age +/- SD was 39.3 +/- 1.6 years . Among the 16 patients for whom this information was available, the interval from the onset of diarrhea to the onset of joint pain was less than 7 days in 7, 8-21 days in 2, and greater than 21 days in 7 . There was a significantly longer duration of diarrhea in those patients with joint disease (mean +/- SEM 15.2 +/- 2.6 days) than in those without complications (10.0 +/- 1.1 days) (P less than 0.01) . The joint disease was monarticular in 3 patients and polyarticular in 16 . The joints most commonly affected were the elbow (47%), wrist (47%), knee (42%), low back (32%), and shoulder (32%) . Six of the 19 patients had at least 1 extraarticular feature: ocular (5 patients), mucosal (1 patient), urethral (2 patients), or cutaneous (1 patient) . Of these 19 patients, 11 were located and agreed to HLA typing . Four were positive for HLA-B27, 6 were HLA-B7 positive, and 1 had HLA-Bw60 . Of the 4 B27 positive patients, 3 were DR1 positive; of the 6 B7 positive patients, 5 were DR2 positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Infect Immun, 1988 Nov, 56(11), 2774 - 81
Damage of the outer membrane of enteric gram-negative bacteria by lactoferrin and transferrin; Ellison RT 3rd et al.; Many studies have shown that lactoferrin and transferrin have antimicrobial activity against gram-negative bacteria, but a mechanism of action has not been defined . We hypothesized that the iron-binding proteins could affect the gram-negative outer membrane in a manner similar to that of the chelator EDTA . The ability of lactoferrin and transferrin to release radiolabeled lipopolysaccharide (LPS) from a UDP-galactose epimerase-deficient Escherichia coli mutant and from wild-type Salmonella typhimurium strains was tested . Initial studies in barbital-acetate buffer showed that EDTA and lactoferrin cause significant release of LPS from all three strains . Further studies found that LPS release was blocked by iron saturation of lactoferrin, occurred between pH 6 and 7.5, was comparable for bacterial concentrations from 10(4) to 10(7) CFU/ml, and increased with increasing lactoferrin concentrations . Studies using Hanks balanced salt solution lacking calcium and magnesium showed that transferrin also could cause LPS release . Additionally, both lactoferrin and transferrin increased the antibacterial effect of a subinhibitory concentration of rifampin, a drug excluded by the bacterial outer membrane . This work demonstrates that these iron-binding proteins damage the gram-negative outer membrane and alter bacterial outer membrane permeability.

Mol Gen Genet, 1988 Nov, 214(3), 579 - 87
The mglB sequence of Salmonella typhimurium LT2; promoter analysis by gene fusions and evidence for a divergently oriented gene coding for the mgl repressor; Benner-Luger D et al.; The mglB gene of Salmonella typhimurium LT2 coding for the galactose-binding protein (GBP) was sequenced . We compared the deduced amino acid sequence with the GBP sequence of Escherichia coli K 12 . The mature proteins differ in only 19 of 309 amino acid residues, corresponding to 94% homology . Analysis of the mglB control region by promoter-probe vectors revealed that two promoters, P1 and P2, constitute the mgl control region (Pmgl) . P1 and P2 function in a synergistic way . P1 is the main promoter of the operon; its activity is 20 times the activity of P2 . Both promoters are activated by the cyclic adenosine monophosphate catabolite activator protein (cAMP/CAP) complex . While P1 is inactive in the absence of the cAMP/CAP complex, there is residual activity of P2 under these conditions . Studies on the inducibility of the mglBAEC operon using multicopy plasmid promoter-probe vectors were hampered by the titration of the mgl repressor resulting in a partially constitutive expression of the mgl operon . The results indicate that only P1 is responding to induction by D-fucose . A weak promoter, PD, within the P1 region but divergent to it was found . PD is neither stimulated by the cAMP/CAP complex nor by D-fucose . We cloned the gene located downstream to PD and found it to strongly repress the expression of the mgl operon . We termed this gene mglD . The presence of D-fucose abolished the repression caused by the plasmid-encoded mglD gene product.

J Bacteriol, 1988 Nov, 170(11), 5125 - 33
Reduced leu operon expression in a miaA mutant of Salmonella typhimurium; Blum PH; Salmonella typhimurium miaA mutants lacking the tRNA base modification cis-2-methylthioribosylzeatin (ms2io6A) were examined and found to be sensitive to a variety of chemical oxidants and unable to grow aerobically at 42 degrees C in a defined medium . Leucine supplementation suppressed both of these phenotypes, suggesting that leucine synthesis was defective . Intracellular levels of leucine decreased 40-fold in mutant strains after a shift from 30 to 42 degrees C during growth, and expression of a leu-lacZ transcriptional fusion ceased . Steady-state levels of leu mRNA were also significantly reduced during growth at elevated temperatures . Failure of miaA mutant leu-lacZ expression to be fully derepressed during L-leucine limitation at 30 degrees C and suppression of the miaA mutation by a mutation in the S . typhimurium leu attenuator suggests that translational control of the transcription termination mechanism regulating leu expression is defective . Since the S . typhimurium miaA mutation was also suppressed by the Escherichia coli leu operon in trans, phenotypic differences between E . coli and S . typhimurium miaA mutants may result from a difference between their respective leu operons.

J Bacteriol, 1988 Nov, 170(11), 5093 - 101
Deduced polypeptides encoded by the Bacillus subtilis sacU locus share homology with two-component sensor-regulator systems; Kunst F et al.; The sacU locus has been cloned by using two independent strategies, and the presence of two open reading frames was deduced from the nucleotide sequence . Open reading frame 1 encodes a 45,000-dalton polypeptide that is similar to the products of the Salmonella typhimurium cheA and Escherichia coli cpxA genes, which act as sensory transducers . Open reading frame 2 encodes a 26,000-dalton polypeptide that is similar to a family of transcriptional activators, including the products of the Bacillus subtilis spoOA and spoOF and the E . coli ompR and dye genes . These similarities suggest that the products of the B . subtilis sacU locus form a sensor-transducer couple, which functions to relay information about specific environmental changes to the transcription apparatus.

Carcinogenesis, 1988 Nov, 9(11), 2103 - 8
Aflatoxin B1 hydroxylation by the pregnenolone-16 alpha-carbonitrile-inducible form of rat liver microsomal cytochrome P-450; Halvorson MR et al.; The effects of treating rats with various pregnenolone-16 alpha-carbonitrile (PCN)-type inducers of cytochrome P-450p on the liver microsomal metabolism of aflatoxin B1 (AFB1) were investigated . Treatment of male rats with PCN resulted in a 6-fold increase in the 9-hydroxylation of AFB1 to aflatoxin Q1 (AFQ1) . Treatment of female rats with PCN resulted in a 16-fold increase in the formation of AFQ1 . The age-dependent decline in constitutive cytochrome P-450p levels in female but not male rats resulted in a sex difference in the formation of AFQ1 in liver microsomes from untreated rats (male:female approximately 3:1) . The formation of AFQ1 was stimulated up to 5.4-fold when liver microsomes from triacetyloleandomycin (TAO)-treated rats were treated with potassium ferricyanide, which dissociates the complex between cytochrome P-450p and TAO . Treatment of male rats with the cytochrome P-450p inducer, dexamethasone, increased (approximately 7-fold) the 9-hydroxylation of AFB1 to AFQ1 by liver microsomes, and also enhanced (approximately 2-fold) the microsomal activation of AFB1 to metabolites that were mutagenic to Salmonella typhimurium TA98 and TA100 . These results indicate that the 9-hydroxylation of AFB1 to AFQ1 is catalyzed by rat liver microsomal cytochrome P-450p.

Cardiovasc Res, 1988 Nov, 22(11), 777 - 85
Effect of insulin on myocardial contractility during canine endotoxin shock; Law WR et al.; During endotoxin shock the heart becomes less responsive to the stimulatory effect of insulin on glucose uptake . In the present study we sought to determine if the heart was also less responsive to the positive inotropic effect of insulin during non-cardiogenic endotoxin shock . Responses of the heart to insulin were assessed under conditions of hyperinsulinaemic (4U.min-1), euglycaemic clamp (INS) . Adult mongrel dogs, weighing 20-25 kg, were anaesthetised and instrumented to measure differences in substrate concentrations between arterial and coronary sinus blood, circumflex artery blood flow (using electromagnetic flow probe), haemodynamic variables, and left ventricular posterior wall thickness (using sonomicrometry) . The first derivative of left ventricular pressure with respect to time was measured and its maximal value (LV dP/dtmax) used as an index of cardiac performance . Myocardial contractility was measured using the end systolic pressure-dimension relationship . Endotoxin shock was induced by Salmonella typhimurium (1 mg.kg-1 intravenously), and resulted in depression of myocardial performance but increased contractility . INS caused a twofold elevation in myocardial glucose uptake in control animals while in endotoxin shocked dogs it was unable to elevate glucose uptake above the pre-endotoxin level . In control animals INS caused both increased cardiac contractility and performance . In the endotoxin shock group INS was unable to increase LVdP/dtmax above the basal, pre-endotoxin level and did not cause any significant change in myocardial contractility . We suggest that the heart becomes less responsive to the positive inotropic as well as metabolic effects of insulin during endotoxin shock . Changes in LV dP/dtmax can be attributed to the changing loading conditions that occur during endotoxin shock.

Am J Vet Res, 1988 Nov, 49(11), 1832 - 5
Effect of efrotomycin in feed on the quantity, duration, and prevalence of shedding and antibacterial susceptibility of Salmonella typhimurium in experimentally infected swine; Jacks TM et al.; The influence of efrotomycin administered at the rate of 16 mg/kg of feed in 10 Salmonella typhimurium-inoculated pigs was determined by comparing this group with a group of 10 pigs inoculated with S typhimurium that were given nonmedicated feed . Two control groups of 4 noninoculated pigs each, 1 group medicated with efrotomycin at 16 mg/kg of feed, the other nonmedicated, also were evaluated . An inoculum of 1.7 x 10(10) colony-forming-units/pig induced colonization of S typhimurium in all 20 pigs . Evaluation of the quantity of shedding did not reveal a clear or consistent treatment-related increase in S typhimurium counts; mean differences between the nonmedicated and medicated groups never exceeded 1 log unit . On the last day of the study (day 56 of the medication), 8 nonmedicated and 9 medicated pigs were determined to be infected with S typhimurium via enrichment procedures, so there was no difference in duration of shedding, and there were no significant differences in prevalence of shedding between the nonmedicated and medicated groups at any of the sampling times . Of 1,340 S typhimurium colonies isolated from the nonmedicated and medicated groups, 1,330 were susceptible to all 12 antibacterials tested, indicating no treatment-related effect on susceptibility . At necropsy, S typhimurium was not isolated from any liver or spleen specimens, and was isolated from only 2 of 20 lymph nodes . However, S typhimurium was isolated via enrichment from the cecal contents from all 20 pigs . There were no treatment-related differences in feed consumption, weight gain, or feed efficiency . Appreciable differences in the measurements were not found between the efrotomycin-medicated and nonmedicated pigs.

Mutagenesis, 1988 Nov, 3(6), 509 - 14
Mutagenic activity in synthetic pyrethroids in Salmonella typhimurium; Herrera A et al.; Four pyrethroids, allethrin, resmethrin, permethrin and fenvalerate, were tested for mutagenicity in bacterial reversion assay systems with seven strains (TA1535, TA100, TA1538, TA98, TA1537, TA97 and TA104) of Salmonella typhimurium . Our results show that three pyrethroids, namely resmethrin, permethrin and fenvalerate, were not found to be mutagenic in S . typhimurium in the presence or absence of a rat liver activation system . Allethrin was found to be mutagenic with TA100, TA104 and TA97 strains and required metabolic activation (S9 mix) in order to show its activity, mainly with TA100 and TA104 strains.

Mutagenesis, 1988 Nov, 3(6), 497 - 502
Mutagenicity of red wine in the L-arabinose resistance test with Salmonella typhimurium; Dorado G et al.; The forward mutation assay to L-arabinose resistance (Ara test) in Salmonella typhimurium detected a Spanish red table wine (Rioja) as a direct-acting mutagen . The best mutagenic response was obtained by preincubating strain BA13 with the wine sample in the presence of sodium phosphate buffer and in the absence of any external metabolic activation . In fact, the S9 mixture abolished most of the mutagenic activity of red wine in the Ara test . Such an inactivating capacity seems to be independent of microsomal enzymes and mediated through some kind of heat-stable component(s) in the S9 fraction . Both regular wine (directly from the bottle) and lyophilized wine were strong mutagens in the Ara test, inducing 4914 and 2739 AraR mutants/ml . Both pKM101 and delta uvrB were critical factors in the detection of the mutagenicity of wine, exhibiting a synergic effect in strain BA13 . The mutagenicity of red wine was somehow pH-dependent, increasing with the pH value of the preincubation mixture . In comparison with the Ara test, the His reverse mutation assay (Ames test) was much less sensitive to the mutagenicity of lyophilized red wine, TA102 being the most (448 His+/ml) and TA98 the least (38 His+/ml) sensitive strain . TA100, TA104 and TA97 manifested intermediate mutagenicities to red wine . Previous reports have identified strain TA98 as the His strain most sensitive to the apolar fraction (e.g . XAD-2-bound) of red wine . Based on these results we propose that TA98 mainly detects glycosides of mutagenic flavonols present in red wine (quercetin, rutin, etc.), which do not constitute the major direct-acting mutagens detected with the Ara test.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutagenesis, 1988 Nov, 3(6), 467 - 80
Mutagenic evaluation of the pesticides captan, folpet, captafol, dichlofluanid and related compounds with the mutants TA102 and TA104 of Salmonella typhimurium; Barrueco C et al.; A mutagenic evaluation of captan, folpet, captafol, dichlofluanid and related compounds was carried out using the Salmonella/mammalian microsome test using strains TA102 and TA104 . These strains contain A-T base pairs at the site of the mutation in contrast to the other Salmonella tester strains that detect mutagens damaging G-C base pairs . In addition, the excision repair system of the TA102 strain is still intact . Captan and folpet were mutagenic in strain TA104, captafol was mutagenic in strain TA102, whereas the remaining test compounds (dichlofluanid, tetrahydrophthalimide and thiozolidine-4-carboxylic acid) were not mutagenic in either strain . In conclusion, we consider it of value to add these two strains to those already used in the Ames test in order to increase confidence in our ability to detect mutagens and to shed further light on their mechanism of action.

J Nat Prod, 1988 Nov-Dec, 51(6), 1226 - 31
Plant antimutagenic agents, 4 . Isolation and structure elucidation of maesol, an inactive constituent of Maesa spp; Wall ME et al.; Maesol, a novel dimeric phenol, was isolated from seeds of Maesa montana and Maesa indica . Maesol was shown to have the formula C28H42O4 with structure 1, a dimeric, symmetrical 1,12-bis(3,3'-dihydroxy-4,4'-dimethyl-5,5'-dimethoxyphenyl)dodecane . It is the first compound with such structure to be isolated from plant material . Structure elucidation was based largely on 1H- and 13C-nmr techniques and comparison with a known synthetic isomeric dimer 3 . Although crude extracts showed strong inhibition of 2-aminoanthracene activity against Salmonella typhimurium (T-98), the pure compound was inactive when tested for inhibition of the mutagenic activity of several mutagens.

J Nat Prod, 1988 Nov-Dec, 51(6), 1084 - 91
Plant antimutagenic agents, 2 . Flavonoids; Wall ME et al.; A number of known prenylated flavonoids were isolated from Psoralea corylifolia using an assay procedure based on inhibition of the mutagenic action of 2-aminoanthracene on Salmonella typhimurium (T-98) . All of these compounds were toxic rather than antimutagenic or desmutagenic . Bakuchiol {17}, a known prenylated phenolic terpene, was also isolated; its activity was not due to toxicity . Biochanin A {4}, a known isoflavone, was similarly isolated from Cicer arientinum and was active and nontoxic . Some of the above flavonoids were studied for inhibition of the mutagenicity of several different mutagens with results depending upon the structure of the flavonoid and the mutagen.

Genetika, 1988 Nov, 24(11), 1928 - 34
{Isolation of mutants with impaired retroinhibition of histidine biosynthesis}; Astvatsaturiants GV et al.; The Escherichia coli, strain possessing purF, deoD and add mutations converts exogenous adenine into guanine nucleotides exclusively by the pathway coupled with histidine biosynthesis . When grown on adenine, this strain demonstrated sensitivity to histidine, thus making it possible to select histidine-resistant hisGR mutants with ATP-phosphoribosyltransferase desensibilized for histidine . The hisGR mutations were obtained in two his operons introduced into the his operon-sensitive E . coli strain: his operon of Salmonella typhimurium incorporated in DNA and his operon of E . coli on the F'episome . In both cases, the hisGR mutants obtained were shown to excrete histidine.

Sangyo Igaku, 1988 Nov, 30(6), 475 - 80
{Mutagenicity of benzene metabolites by fluctuation test}; Koike N et al.; Mutagenicity of five benzene metabolites was examined by a fluctuation test modified by Gatehouse . The test was performed by using Salmonella typhimurium TA100 with or without a metabolic activation system . Catechol showed mutagenic activity with and without a metabolic activation system in the fluctuation test . Hydroxyhydroquinone, phenol, hydroquinone and p-benzoquinone were positive only with a metabolic activation system in this test . The Ames' plate method and preincubation method are widely used as a screening test for the mutagenic compounds . However, the fluctuation test is very useful in detecting mutagenic activity of chemicals which are negative in the Ames test though being a mutagen or carcinogen.

Mol Microbiol, 1988 Nov, 2(6), 749 - 55
Mutations of putP that alter the lithium sensitivity of Salmonella typhimurium; Myers RS et al.; The putP gene encodes the major proline permease in Salmonella typhimurium that couples transport of proline to the sodium electrochemical gradient . To identify residues involved in the cation binding site, we have isolated putP mutants that confer resistance to lithium during growth on proline . Wild-type S . typhimurium can grow well on proline as the sole carbon source in media supplemented with NaCl, but grows poorly when LiCl is substituted for NaCl . In contrast to the growth phenotype, proline permease is capable of transporting proline via Na+/proline or Li+/proline symport . Therefore, we selected mutants that grow well on media containing proline as the sole carbon source in the presence of lithium ions . All of the mutants assayed exhibit decreased rates of Li+/proline and Na+/proline cotransport relative to wild type . The location of each mutation was determined by deletion mapping: the mutations cluster in two small deletion intervals at the 5' and 3' termini of the putP gene . The map positions of these lithium resistance mutations are different from the locations of the previously isolated substrate specificity mutations . These results suggest that Lir mutations may define domains of the protein that fold to form the cation binding site of proline permease.

Food Chem Toxicol, 1988 Nov-Dec, 26(11-12), 917 - 9
Effects of the nitrosopeptide N-(N-acetyl-L-prolyl)-N-nitrosoglycine on Salmonella typhimurium TA100 in the host-mediated assay in mice; Blowers SD et al.; The N-nitrosopeptide N-(N-acetyl-L-prolyl)-N-nitrosoglycine (APNG) was examined for mutagenicity in the mouse host-mediated assay using Salmonella typhimurium strain TA100 . Administration of APNG orally or as a single ip injection was shown to produce an increase in revertants . This study provides the first evidence that APNG is absorbed after oral administration in mice and demonstrates that the mutagenic product of APNG is short-lived in vivo.

Mutat Res, 1988 Nov, 206(3), 411 - 27
Ames test: mutagenic activity of airborne particles collected on airconditioner filters during the fire at a Sandoz storehouse in Schweizerhalle on November 1, 1986; Suter W; The mutagenic activity of methanol extracts from airconditioner filters was tested using the standard plate-incorporation procedure for the Ames test and the strains Salmonella typhimurium TA97, TA98 and TA100 as test organisms . In a first set of experiments filters from 4 buildings were investigated . For each building the mutagenic activity of a filter which was in use during the fire (fire-exposed) was compared with the mutagenic activity of a filter which was exposed for a similar time span to normal urban air (non-exposed) . While for 1 pair of filters the non-exposed extract was more mutagenic than the fire-exposed material, the opposite was found for 2 other filter pairs, and in 1 case there was hardly any difference in the mutagenic activities of the fire-exposed and the non-exposed filter extracts . Overall differences by factors up to 100 were observed in the mutants/m3 air values of the most and the least mutagenic filter extracts . The second group of experiments was performed to investigate the variations in mutagenic activity of filter extracts occurring due to changes in the weather conditions . Airborne particles were collected for 3 consecutive periods of 10-11 days at the 2 buildings where the extracts of the fire-exposed filters had been found to be more mutagenic than the corresponding control materials . The differences between the strongest and the weakest mutagenic filter extracts of these series were similar to the differences observed previously between the fire-exposed filters and the non-exposed filter materials . The highest mutagenic activities found in the second group of experiments was similar, at both sites, to the mutagenic activities measured in the fire-exposed extracts from these 2 buildings . Since the differences in the mutagenic activities of filters exposed to urban air during the different meteorological conditions were similar to the differences observed between fire-exposed and non-exposed materials, it is not possible to state whether the fire led to the distribution of mutagenic chemicals, although it is theoretically possible . However, based on the observation that the maximal mutagenic activities of the fire-exposed and the non-exposed extracts were similar, the present study allows the conclusion that the mutagenic burden for the population of the area of Basel was not significantly increased by the fire in Schweizerhalle on November 1, 1986.

Mutat Res, 1988 Nov, 206(3), 327 - 34
Effects of medicinal plant extracts from Chinese herbal medicines on the mutagenic activity of benzo{a}pyrene; Sakai Y et al.; The effects of medicinal plants on the mutagenicity of benzo{a}pyrene were studied with Salmonella typhimurium tester strains . The chosen medicinal plants are very frequently used as Chinese herbal medicines . Each medicinal plant was extracted with hot water, which is similar to the method used in Chinese medicinal treatment . Cinnamomi cortex, Rhei rhizoma, Scutellariae radix and Rehmanniae radix were found to decrease the mutagenic activity of benzo{a}pyrene . Atractylodis rhizoma also reduced the mutagenicity of benzo{a}pyrene, but this was not certain, because it showed a killing effect on the cell survival test . Bupleuri radix and Aurantii nobilis pericarpium had an enhancing effect, but then neither of these extracts is itself mutagenic . Each medicinal plant extract showed a different effect on the mutagenicity of benzo{a}pyrene . These effects were classified into 5 types: (I) decreasing effect, (II) killing effect, (III) enhancing effect, (IV) enhancing and decreasing effect and (V) inactive.

Mutat Res, 1988 Nov, 206(3), 317 - 26
Mutagenicity of 4-aminoantipyrine and 4-nitrosoantipyrine, the C-nitroso derivative of antipyrine; Parisis DM et al.; The drug antipyrine and its 4-substituted analogs, 4-aminoantipyrine, 4-dimethylaminoantipyrine (aminopyrine) and 4-nitrosoantipyrine were tested for mutagenicity against the screening array of Salmonella typhimurium tester strains TA100, TA98, TA97, TA102 and TA104 . Antipyrine and aminopyrine were nonmutagenic to all 5 tester strains even in the presence of S9 . 4-Aminoantipyrine was directly mutagenic to TA97 only and the presence of S9 slightly increased its activity . 4-Nitrosoantipyrine was directly mutagenic to all tester strains used and S9 decreased its activity except with strain TA102 . The possible long-term hazards of C-nitroso compounds derived from drugs and dietary constituents are discussed in view of their pluripotent direct genotoxicity.

Mutat Res, 1988 Nov-Dec, 209(3-4), 95 - 8
Formation of a diazoquinone-type mutagen from acetaminophen treated with nitrite under acidic conditions; Ohta T et al.; Acetaminophen (paracetamol) showed mutagenicity to Salmonella typhimurium TA100 and TA98 either with or without S9 mix when treated with excess nitrite in acidic solution . The mutagen was isolated and identified as 4-acetylamino-6-diazo-2,4-cyclohexadienone . Mutation tests and product analysis by high-performance liquid chromatography, however, suggested that this type of mutagen was hardly formed in the digestive tract of normal subjects.

Mutat Res, 1988 Nov-Dec, 209(3-4), 123 - 9
Nitroreduction of 6-nitrobenzo{a}pyrene: a potential activation pathway in humans; Fu PP et al.; 6-Nitrobenzo{a}pyrene, an environmental pollutant, was metabolized by human intestinal microflora to 6-nitrosobenzo{a}pyrene and 6-aminobenzo{a}pyrene . The two-electron reduction product 6-nitrosobenzo{a}pyrene exhibited strong direct-acting mutagenicity in the Salmonella typhimurium assay . These results imply that 6-nitrobenzo{a}pyrene can be hazardous to human health via a nitroreduction activation pathway and opens the possibility that other nitro-polycyclic aromatic hydrocarbons that are not direct-acting mutagens may be activated in vivo by a similar mechanism.

Mutat Res, 1988 Nov-Dec, 209(3-4), 115 - 22
Relationships among direct-acting mutagenicity, nitro group orientation and polarographic reduction potential of 6-nitrobenzo{a}pyrene, 7-nitrobenz{a}anthracene and their derivatives; Fu PP et al.; The direct-acting mutagenicity in Salmonella typhimurium strains TA98 and TA100 and the half-wave reduction potentials of 6-nitrobenzo{a}pyrene (6-nitro-BaP), 7-nitrobenz{a}anthracene (7-nitro-BA), and a series of their derivatives were compared . The common structural feature of these compounds is that their nitro substituents, in order to minimize steric hindrance, preferentially adopt an orientation perpendicular or nearly perpendicular to the aromatic rings . All of the compounds, except 7-hydroxy-6-nitro-BaP and 7-acetoxy-6-nitro-BaP, were found to exhibit very weak or no direct-acting mutagenicity . 7-Acetoxy-6-nitro-BaP and 7-hydroxy-6-nitro-BaP were also found to have the lowest reduction potentials among the tested compounds . The results suggest that a combination of the orientation of the nitro substituent and the first half-wave reduction potential of the compound may correlate with the direct-acting bacterial mutagenicity of nitro-polycyclic aromatic hydrocarbons.

Eur J Biochem, 1988 Nov 1, 177(2), 363 - 9
Genes coding for RNA polymerase beta subunit in bacteria . Structure/function analysis; Lisitsyn NA et al.; The nucleotide sequence of the rpoB gene of Salmonella typhimurium has been determined in this work . It was compared with known sequences of the gene from other sources and the conservative regions were detected . This allowed some interesting conclusions to be made about the distribution of the functional domains in bacterial RNA polymerase and about the three-dimensional structure of its beta subunit.

Toxicol Lett, 1988 Nov, 44(1-2), 191 - 200
Synergistic interaction between the trichothecene T-2 toxin and Salmonella typhimurium lipopolysaccharide in C3H/HeN and C3H/HeJ mice; Tai JH et al.; The capacity of the trichothecene T-2 toxin to alter resistance to bacterial lipopolysaccharide (LPS) was examined in the mouse . Both LPS-susceptible (C3H/HeN) and LPS-resistant (C3H/HeJ) mouse strains exhibited markedly enhanced mortality when a single oral dose of T-2 toxin (1 mg/kg) was coadministered with a subacute i.p . dose of Salmonella typhimurium LPS . In the absence of LPS, T-2 toxin did not cause lethal effects when administered at this level . LD50 values for LPS decreased by 14-fold and 4.5-fold upon co-administration with T-2 toxin (1 mg/kg) in C3H/HeN and C3H/HeJ mice, respectively . Increased mortality was accompanied by an impaired splenic response to LPS in C3H/HeN mice . C3H/HeN mice pretreated with a sublethal dose of LPS 24 h prior to T-2 toxin administration also exhibited significantly increased susceptibility to T-2 toxin . Histopathological assessment revealed that the liver and spleen of mice exposed to T-2 toxin and LPS exhibited extensive cell death as compared to control mice treated with T-2 toxin or LPS only . The results suggest that bacterial LPS and trichothecenes such as T-2 toxin interact synergistically . This interaction may contribute to increased mortality that has been observed previously in animals challenged with Salmonella and T-2 toxin.

Proc Natl Acad Sci U S A, 1988 Nov, 85(21), 8047 - 51
Two dominant-acting selectable markers for gene transfer studies in mammalian cells; Hartman SC et al.; We report the development of two dominant-acting genetic markers useful for monitoring gene transfer in mammalian cells that are based on prokaryotic genes encoding key steps in the synthesis of the essential amino acids, tryptophan and histidine . Under appropriate conditions, expression of these genes obviates the nutritional requirements for their respective amino acid products . Expression of the trpB gene of Escherichia coli, which encodes the beta subunit of tryptophan synthase (EC 4.2.1.20), allows mammalian cell survival and multiplication in medium containing indole in place of tryptophan . The hisD gene of Salmonella typhimurium encodes histidinol dehydrogenase (EC 1.1.1.23), which catalyzes the two-step NAD+-dependent oxidation of L-histidinol to L-histidine . In medium lacking histidine and containing histidinol, only mammalian cells expressing the hisD product survive . The selection is a double one in that the provided precursor histidinol is itself toxic to animal cells through its inhibition of histidyl-tRNA synthetase; thus, the dehydrogenase both removes an inhibitor and forms a required end product . Alternatively, the his selection may be carried out under conditions in which the dehydrogenase serves mainly to detoxify histidinol . For either the trp or his selections the substitute nutrient (indole or histidinol) is readily available, inexpensive, stable, permeable to cells, and convertible to the end product in a step controlled by a single gene . Vectors based upon murine retrovirus and papovavirus backbones have been successfully employed for both genes, allowing selection in a range of cell types, including 3T3, CV-1, and HeLa . These dominant selective schemes should provide generally useful and inexpensive alternatives to others currently in use, such as the gpt, neo, hygro, dhfr, and tk selections.

Mutat Res, 1988 Nov, 202(1), 59 - 64
Catalase inhibition by sulfide and hydrogen peroxide-induced mutagenicity in Salmonella typhimurium strain TA102; Carlsson J et al.; The lethal and mutagenic effects of hydrogen peroxide were studied in exponentially growing cultures of Salmonella typhimurium strain TA102 . Exposure of the cultures to non-lethal levels of sodium sulfide significantly increased the lethality and mutagenicity of hydrogen peroxide . The catalase activity was decreased in cells exposed to sodium sulfide, but there were no changes in the cellular levels of superoxide dismutase, glutathione reductase, or NADPH-dependent alkyl hydroperoxide reductase . Hydrogen peroxide-induced mutagenesis and killing of S . typhimurium strain TA102 in the presence of sulfide may in part be explained by an inactivation of catalase by sulfide.

Mutat Res, 1988 Nov, 202(1), 119 - 23
Presence of nitrosable mutagen precursors in cooked meat and fish; Yano M et al.; Broiled chicken, pork, mutton, beef and sun-dried sardine were found to yield direct-acting mutagenicity after nitrite treatment . When 50% methanol extracts of cooked foods were treated with 50 mM nitrite at pH 3 for 1 h at 37 degrees C, they induced 3800-17,900 revertants of Salmonella typhimurium TA100 and 15,000-43,600 revertants of TA98 per g . In contrast, raw meat and uncooked sun-dried sardine showed little or no mutagenicity after nitrite treatment . Treatment of broiled chicken with 0.5-3 mM nitrite, which is a physiologically feasible concentration in the human stomach under some conditions, induced direct-acting mutagenicity . When broiled chicken was treated with 1 mM nitrite at pH 3 for 1 h at 37 degrees C, its mutagenicities on TA100 and TA98 without S9 mix were 7100 and 5400 revertants/g, respectively.

Chem Res Toxicol, 1988 Nov-Dec, 1(6), 349 - 55
Synthesis and tumor-initiating activities of dimethylchrysenes; Amin S et al.; Previous studies have shown that 5-methylchrysene (5-MeC) is more carcinogenic on mouse skin than the other methylchrysenes and that the structural requirements favoring tumorigenicity of methylated polynuclear aromatic hydrocarbons are the presence of a bay region methyl group and free peri position, both adjacent to an unsubstituted angular ring . The purpose of this study was to extend these structure-activity relationships to dimethylchrysenes . The following dimethylchrysenes were synthesized: 1,5-dimethylchrysene (1,5-diMeC), 5,6-diMeC, 5,7-diMeC, 5,12-diMeC, 1,6-diMeC, 6,7-diMeC, and 6,12-diMeC . Bioassays of these compounds for tumor-initiating activity on mouse skin demonstrated that all were significantly less tumorigenic than 5-MeC; only 5,6-diMeC had significant tumorigenic activity . Since the relatively low activities of 5,7-diMeC and 5,6-diMeC were unexpected on the basis of the structural requirements stated above, anti-1,2-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydro-5,7-dimethylchrysene+ ++ (anti-5,7-diMeC-1,2-diol-3,4-epoxide) was synthesized . Its mutagenicity in Salmonella typhimurium and reactivity with calf thymus DNA were compared to those of the major ultimate carcinogen of 5-MeC, anti-5-MeC-1,2-diol-3,4-epoxide . It was strongly mutagenic (2500 revertants/nmol), although less active than anti-5-MeC-1,2-diol-3,4-epoxide (7200 revertants/nmol) . Its reactivity with calf thymus DNA was similar to that of anti-5-MeC-1,2-diol-3,4-epoxide . The results of this study demonstrate that the structural requirements which favor tumorigenicity of monomethylchrysenes are not sufficient for high tumorigenicity of dimethylchrysenes.

Mol Gen Mikrobiol Virusol, 1988 Nov, (11), 29 - 35
{Sucrose utilization determinants of transposon Tn2555}; Doroshenko VG et al.; The Sac- -derivatives of the plasmid pBRS5.2 containing the sucrose utilization transposon Tn2555 were obtained by using the insertional mutagenesis . The sac mutations were mapped within the transposons DNA fragment of about 3kb . The existence of two linkage groups of the sac mutations was shown by complementation analysis . Among the gene products of Tn2555 the polypeptides of about 58, 36, 27, 14 and 12 kd were found . The data on relation of the sac genes of Tn2555 and the ones of the known plasmid pUR400 of Salmonella typhimurium are discussed.

Radiat Res, 1988 Nov, 116(2), 292 - 304
His+ reversions caused in Salmonella typhimurium by different types of ionizing radiation; Roos H et al.; The yield of his+ reversions in the Ames Salmonella tester strain TA2638 has been determined for 60Co gamma rays, 140 kV X rays, 5.4 keV characteristic X rays, 2.2 MeV protons, 3.1 MeV alpha particles, and 18 MeV/U Fe ions . Inactivation studies were performed with the same radiations . For both mutation and inactivation, the maximum effectiveness per unit absorbed dose was obtained for the characteristic X rays, which have a dose averaged linear energy transfer (LET) of roughly 10 keV/micron . The ratio of the effectiveness of this radiation to gamma rays was 2 for inactivation and about 1.4 for the his+ reversion . For both end points the effectiveness decreases substantially at high LET, i.e., for the alpha particles and the Fe ions . The composition of the bottom and the top agar was the one recommended by Maron and Ames {Mutat . Res . 113, 173-215 (1983)} for application in chemical mutagenicity tests . The experiments with the less penetrating radiations differed from the usual protocol by utilization of a technique of plating the bacteria on the surface of the top agar . As in an earlier study {Roos et al., Radiat . Res . 104, 102-108 (1985)} greatly enhanced yields of mutations, relative to the spontaneous reversion rate, were obtained in these experiments by performing the irradiations 6 h after plating, which differs from the conventional procedure to irradiate the bacteria shortly after plating.

Carcinogenesis, 1988 Nov, 9(11), 2003 - 8
Superoxide dismutase-mediated reversible conversion of 3-hydroxyamino-1-methyl-5H-pyrido{4,3-b}indole, the N-hydroxy derivative of Trp-P-2, into its nitroso derivative; Hiramoto K et al.; Aerobic oxidation of 3-hydroxyamino-1-methyl-5H-pyrido-{4,3-b}indole {Trp-P-2(NHOH)} in neutral aqueous solution was greatly accelerated by copper-zinc superoxide dismutase (SOD) . The major product in this SOD-mediated reaction was identified as 3-nitroso-1-methyl-5H-pyrido{4,3-b}indole {Trp-P-2(NO)} . This conversion was accompanied by a decrease of the mutagenicity of the mixture, as monitored by the direct-acting mutagenicity on Salmonella typhimurium TA98; a rapid change to approximately 1/3 of the original mutagenicity was followed by no further decrease of the activity . In contrast, in the spontaneous aerobic oxidation of Trp-P-2-(NHOH), the mutagenicity slowly and continuously decreased, until it was finally lost almost completely . Similar acceleration by SOD of aerobic oxidation was found for 2-hydroxyamino-6-methyldipyrido{1,2-a:3',2'-d}imidazole {Glu-P-1(NHOH)} . Again, mutagenicity of approximately 1/4 that of the original was retained in the SOD-mediated decomposition, while a complete loss of the mutagenicity was observed in the spontaneous decomposition . When Trp-P-2(NO) was treated with the superoxide-generating system, xanthine oxidase plus xanthine, Trp-P-2(NHOH) was formed . Therefore, the role of SOD in the conversion of Trp-P-2(NHOH) into Trp-P-2(NO) is the removal of superoxide anions generated by reduction of aerobic oxygen, thereby inhibiting the reverse reactions, i.e . the reduction of Trp-P-2(NO) and that of the putative intermediate nitroxide radical . In support of this proposed mechanism, phenylhydroxylamine underwent a SOD-accelerated conversion to nitrosobenzene, and nitrosobenzene was reduced to phenylhydroxylamine by the action of the xanthine oxidase-xanthine system . Hence, this reversible interchange between an arylhydroxylamine and its nitroso compound, coupled with the oxygen-superoxide cycle, may be a general phenomenon . A consequence of this finding is that the xenobiotic N-hydroxylamines may be converted by the action of SOD in the biological settings into nitroso compounds, which are chemically more stable, serving as a reservoir for mutagenicity.

Infect Immun, 1988 Nov, 56(11), 2953 - 9
Protection against Salmonella typhi infection in mice after immunization with outer membrane proteins isolated from Salmonella typhi 9,12,d, Vi; Isibasi A et al.; The current studies were undertaken to assess the ability of the outer membrane proteins (OMPs) of Salmonella typhi to induce protection against challenge with the bacteria in mucin . OMPs were isolated as described by Schnaitman (J . Bacteriol . 108:553-556, 1971) and were found to be contaminated with approximately 4% lipopolysaccharide (LPS) . Immunization with as little as 30 micrograms of OMPs conferred 100% protection to mice challenged with up to 1,000 50% lethal doses (LD50) of two strains of S . typhi (9,12,d, Vi and Ty2) . In addition, 30% protection against challenge with up to 500 LD50 of Salmonella typhimurium was achieved . Immunization with LPS at doses equivalent to those found in the OMPs was considerably inferior to the OMPs in the induction of an immune status . Moreover, LPS was effective only when the challenge was performed with S . typhi 9,12,d, Vi (40% protection to 100 LD50) . An antiserum raised in rabbits reacted mainly against the bands of the molecular weights corresponding to the so-called porins contained in the OMP preparation as shown by Western blotting (immunoblotting) . This rabbit antiserum protected 100% of mice against challenge with 100 LD50 of either strain of S . typhi and 80% of mice against challenge with the same LD50 of S . typhimurium . These results indicate the usefulness of OMPs in the induction of active immunity against S . typhi in mice.

Zentralbl Bakteriol Mikrobiol Hyg {A}, 1988 Nov, 270(1-2), 260 - 9
Infection and immunity to Vibrio cholerae, Salmonella typhimurium and Escherichia coli in a rabbit model; Guinee PA et al.; Cholera disease can be induced in the rabbit by duodenal inoculation (DI) of Vibrio cholerae organisms after ligation of the cecum (C) (DIC model) . When ligation of the cecum is omitted, no disease symptoms develop . In contrast, the animals are primed which becomes apparent as vibriocidal protection upon challenge with V . cholerae in the DIC model . This protection coincides with high anti-O antigen IgA levels in the bile . The O antigen was shown to be the protective antigen and it must be presented by live organisms . A non-enterotoxigenic mutant of V . cholerae induced protective immunity in the rabbit but was reported to cause mild diarrhea in human volunteers . Looking for alternatives, we applied cholera toxin, known as a mucosal adjuvant, together with killed V . cholerae cells to rabbits . Unfortunately, the minimum adjuvant dose was equal to the minimum toxic dose . A Salmonella typhimurium strain expressing also the V . cholerae O antigen induced systemic rather than local immunity which was not protective . Several Escherichia coli strains were able to elicit a local immune response, but the animal to animal differences were considerable . Therefore, V . cholerae itself was thought to be the most appropriate carrier organism . Some non-enterotoxigenic and auxotrophic mutants of V . cholerae were able to prime and did not show any undesired side-effects in the DIC model . Therefore, further attenuation of non-toxigenic V . cholerae strains by means of stable deletions in nutritional genes seems to be the most promising way to obtain acceptable vaccine candidates.

J Biol Chem, 1988 Oct 25, 263(30), 15823 - 30
Periplasmic nonspecific acid phosphatase II from Salmonella typhimurium LT2 . Crystallization, detergent reactivation, and phosphotransferase activity; Uerkvitz W; The periplasmic nonspecific acid phosphatase II from Salmonella typhimurium was purified to homogeneity from a mutant strain that overproduces the enzyme (Uerkvitz, W., and Beck, C.F . (1981) J . Biol . Chem . 256, 382-389) . It was shown that the enzyme transfers phosphate groups from organic phosphoric acid esters (donors) to water as well as to the 2'-, 3'-, or 5'-hydroxyls of nucleosides, nucleotides, and other compounds with free hydroxyl groups (acceptors) . The enzyme was crystallized in two forms by precipitation with polyethylene glycol . Needles were formed in buffer containing Mg2+, whereas thin rectangular plates appeared in the presence of the non-ionic detergent n-octyl glucoside . Sodium dodecyl sulfate-polyacrylamide gel electrophoresis under partially or completely denaturating conditions revealed that the native enzyme is a tetramer consisting of identical 24-kDa monomers . Owing to surface inactivation, polyethylene glycol, non-ionic, or Zwitterionic detergents are indispensable for enzyme stability . The detergents are able to reactivate inactivated enzyme when present near or above their critical micelle concentration.

J Biol Chem, 1988 Oct 25, 263(30), 15429 - 35
Specificity of mutagenesis by 4-aminobiphenyl . A possible role for N-(deoxyadenosin-8-yl)-4-aminobiphenyl as a premutational lesion; Lasko DD et al.; Mutagenesis by N-acetoxy-N-trifluoroacetyl-4-aminobiphenyl, a reactive form of the human bladder carcinogen 4-aminobiphenyl (ABP), was studied in Escherichia coli virus M13mp10 . N-acetoxy-N-trifluoroacetyl-4-ABP-treated DNA containing 140 lesions/duplex genome, when introduced into excision repair-competent cells induced for SOS mutagenic processing, resulted in a 40-fold increase in mutation frequency over background in the lacZ alpha gene fragment . DNA sequence changes were determined for 20 independent mutants . G-C base pairs were the major targets for base pair substitution mutations, although significant mutagenic activity was also observed at certain A-T base pairs . Deletion and frameshift mutations also were found in this sample . The salient feature of this partial "mutational spectrum" was a hotspot that occurred at position 6357 (amino acid 30 of the beta-galactosidase fragment encoded by M13mp10); this A-T to T-A transversion appeared in 6 of the 20 mutants . The property of ABP to mutate A-T base pairs was consistent with the result that N-hydroxy-ABP reverted Salmonella typhimurium strain TA104, which is presumed to revert primarily due to mutations at these sites . The ability of the major carcinogen-DNA adduct formed by ABP in vivo and in vitro, N-(deoxyguanosin-8-yl)-4-aminobiphenyl, to cause base pair substitution mutations was also investigated . This adduct was positioned specifically in the minus strand at position 6270 in duplex M13mp10 DNA . In the presence of the mutagenesis-enhancing plasmid pGW16 and UV induction of SOS mutagenic processing, it was shown that fewer than 0.02% of the adducts resulted in transition or transversion mutations following transfection of DNA into excision-repair competent cells . Similar results were obtained in uvrA and uvrC backgrounds . Although the major adduct did not cause base substitution mutations under these experimental conditions, the contribution of this lesion to the entire spectrum of mutations in the lacZ alpha fragment seems likely.

Cell, 1988 Oct 21, 55(2), 351 - 60
In vivo analysis of the mechanisms responsible for strong transcriptional polarity in a "sense" mutant within an intercistronic region; Alifano P et al.; We have studied a very unusual strong polar mutant in the intercistronic barrier between the second (hisD) and third (hisC) cistrons of the histidine operon of Salmonella typhimurium to obtain further insights into the molecular mechanisms leading to transcription termination within cistrons . We have performed a detailed transcriptional analysis in vivo and have found that the his mRNA in this polar mutant is reduced in size as a result of premature termination of transcription at a cryptic Rho-dependent site within the proximal region of the hisC cistron.

J Biol Chem, 1988 Oct 15, 263(29), 15104 - 9
Chloroplast transport of a ribulose bisphosphate carboxylase small subunit-5-enolpyruvyl 3-phosphoshikimate synthase chimeric protein requires part of the mature small subunit in addition to the transit peptide; Comai L et al.; Ribulose bisphosphate carboxylase small subunit protein is synthesized in the cytoplasm as a precursor and transported into the chloroplast where the amino-terminal portion, the transit peptide, is removed proteolytically . To obtain chloroplast delivery of the 43-kDa 5-enolpyruvyl 3-phosphoshikimate (EPSP) synthase of Salmonella typhimurium, we constructed fusion proteins between the bacterial EPSP synthase and the ribulose bisphosphate carboxylase small subunit . A fusion protein consisting of the transit peptide fused to the EPSP synthase was not transported in vitro or in vivo into chloroplasts . A second fusion protein consisting of the transit peptide and 24 amino acids of the mature small subunit fused to the EPSP synthase was transported both in vitro and in vivo into chloroplasts . It was processed into two polypeptides of 46 and 47 kDa, respectively . This heterogeneity in processing was not caused by the presence of the aroA start codon, since its removal resulted in the same pattern . Substituting 24 different amino acids for the 24 amino acids of the mature small subunit resulted in a fusion protein that was not transported into the chloroplast . It was concluded that a portion of the mature small subunit was needed for efficient chloroplast delivery.

J Mol Biol, 1988 Oct 5, 203(3), 585 - 606
Structure and function of the Salmonella typhimurium and Escherichia coli K-12 histidine operons; Carlomagno MS et al.; We have determined the complete nucleotide sequence of the histidine operons of Escherichia coli and of Salmonella typhimurium . This structural information enabled us to investigate the expression and organization of the histidine operon . The proteins coded by each of the putative histidine cistrons were identified by subcloning appropriate DNA fragments and by analyzing the polypeptides synthesized in minicells . A structural comparison of the gene products was performed . The histidine messenger RNA molecules produced in vivo and the internal transcription initiation sites were identified by Northern blot analysis and S1 nuclease mapping . A comparative analysis of the different transcriptional and translational control elements within the two operons reveals a remarkable preservation for most of them except for the intercistronic region between the first (hisG) and second (hisD) structural genes and for the rho-independent terminator of transcription at the end of the operon . Overall, the operon structure is very compact and its expression appears to be regulated at several levels.

Mutat Res, 1988 Oct, 203(5), 333 - 8
A simple method for assessment of rat cytochrome P-448 isozymes responsible for the mutagenic activation of carcinogenic chemicals; Degawa M et al.; Cytochrome P-448H/L-enriched and cytochrome P-448L-enriched microsomes were prepared from the livers of Sprague-Dawley rats treated with 3-methylcholanthrene (MC) and with a combination of MC and carbon tetrachloride, respectively, and their activities for mediating mutagenic activation of 9 carcinogenic aromatic amines and benzo{a}pyrene, which are found to be different from cyt . P-450 isozymes as to mutagenic activation, were compared on the basis of microsomal cytochrome P-450 content using Salmonella typhimurium TA98 as a tester bacterium . With regard to the substrate-specificity of cytochrome P-448 isozymes, the present results reflected the reported results with use of a cytochrome P-450-reconstituted system . These findings indicate that the mutation test with cytochrome P-448H/L-enriched and cytochrome P-448L-enriched microsomes could be used as a simple method for the determination of the cytochrome P-448 isozymes responsible for the mutagenic activation of carcinogens and mutagens without the use of a cytochrome P-450-reconstituted system.

J Antimicrob Chemother, 1988 Oct, 22 Suppl D, 123 - 7
Comparative activities of norfloxacin and fleroxacin in experimental infections due to Salmonella typhimurium and Escherichia coli; Hof H et al.; Norfloxacin and fleroxacin displayed similar in-vitro activity against test strains of Escherichia coli (MIC 0.06 mg/l) and Salmonella typhimurium (0.125 mg/l) . Septicaemic infection of mice with E . coli could be almost cured by quinolones but not by ampicillin . Fleroxacin was more potent than norfloxacin . Infection of mice with S . typhimurium was much more difficult to treat . In spite of higher doses the bacterial counts remained at a considerable level . Again, fleroxacin was more active in vivo than norfloxacin.

Microb Pathog, 1988 Oct, 5(4), 275 - 85
The role of the traT gene of the Salmonella typhimurium virulence plasmid for serum resistance and growth within liver macrophages; Rhen M et al.; The role of the traT gene of the Salmonella typhimurium virulence plasmid for the serum resistance of the bacteria and their growth within mouse liver macrophages was investigated . The gene product, the TraT protein, increased the serum resistance in E . coli HB101, which naturally does not carry traT . It also contributed to the serum tolerance of S . typhimurium . The capacity of an isogenic S . typhimurium TML strain triplet, differing in their ability to express TraT and in the quality of the traT gene expressed, to grow in vivo in the mouse liver indicated that, although TraT was dispensable for the net growth of the bacteria within the liver, the expression of a mutated traT gene reduced the growth rate . The traT gene was mapped on the virulence plasmid outside previously defined virulence determinants suggesting that other regions of the virulence plasmid are mainly responsible for the growth within mouse liver macrophages in S . typhimurium.

Fundam Appl Toxicol, 1988 Oct, 11(3), 429 - 39
Evaluation of propanil and its N-oxidized derivatives for genotoxicity in the Salmonella typhimurium reversion, Chinese hamster ovary/hypoxanthine guanine phosphoribosyl transferase, and rat hepatocyte/DNA repair assays; McMillan DC et al.; Since the herbicide propanil (3,4-dichloropropionanilide) is an aromatic amide and many other aromatic amides are genotoxic via N-hydroxy (N-OH) metabolites, N-oxidized derivatives of propanil and 3,4-dichloroaniline were synthesized and tested for genotoxicity . Propanil 3,4-dichloroaniline, and their N-OH derivatives were not mutagenic in the Salmonella typhimurium reversion assay using tester strains TA97, TA98, TA100, and TA104, in both the presence and absence of exogenous metabolic activation (S9) . In addition, the test compounds were not mutagenic in the Chinese hamster ovary/hypoxanthine guanine phosphoribosyl transferase (CHO/HGPRT) assay, in both the presence and absence of S9 . 3,3',4,4'-Tetrachloroazobenzene (TCAB) and its azoxy derivative (TCAOB), which are synthetic contaminants and/or degradation products of propanil, were also inactive in the S . typhimurium reversion and CHO/HGPRT assays (+/- S9) . Unscheduled DNA synthesis (UDS) assays were performed to determine if propanil derivatives were able to induce DNA damage in primary rat hepatocytes . Although TCAB was the only derivative tested which induced an elevation in DNA repair, the extent was not statistically significant . Hepatocyte toxicity, as measured by the release of lactate dehydrogenase 24 hr after exposure, was induced by all the test compounds in a concentration-dependent manner . Incubations of {14C}N-OH-3,4-dichloroaniline with DNA in vitro resulted in only a low level of binding that was not affected by pH . This observation may partially explained the lack of mutagenicity observed in genotoxicity assays with propanil derivatives.

Vaccine, 1988 Oct, 6(5), 387 - 9
Towards a live oral vaccine against enterotoxigenic Escherichia coli of swine; Attridge S et al.; A live oral vaccine has been developed against scouring induced in piglets by enterotoxigenic Escherichia coli (ETEC) . An attenuated strain of Salmonella typhimurium, G30, has been used as a vector for plasmids encoding the production of the fimbrial colonization factors of porcine ETEC . Initial studies with clones expressing K88 or K99 fimbriae have shown them to be well tolerated when administered orally in very high doses . The clones elicited serum, colostral and milk antibodies to the fimbrial antigens, and a challenge trial indicated that such responses were sufficient to ensure the passive transfer of protective immunity to suckling piglets . The possible advantages of this approach are discussed.

J Periodontol, 1988 Oct, 59(10), 684 - 7
Lipopolysaccharide-stimulated PGE2 release from human monocytes . Comparison of lipopolysaccharides prepared from suspected periodontal pathogens; Garrison SW et al.; Lipopolysaccharides (LPS) prepared from the suspected periodontal pathogens Actinobacillus actinomycetemcomitans (A . a.), Bacteroides gingivalis, B . intermedius and Wolinella recta were compared to Salmonella typhimurium LPS for their capacity to stimulate prostaglandin E2 (PGE2) release from human monocytes . Counterflow isolated monocytes were cultured with control medium or media containing 10 micrograms/ml LPS . Media were then exchanged every 24 hours for a total of 72 hours . Salmonella and Wolinella LPS preparations demonstrated seven-fold greater PGE2 release than B . gingivalis and two-fold greater than A . a . and B . intermedius . PGE2 release was found to decrease over time with all LPS preparations except Wolinella . The potency of the LPS preparations is tentatively ranked as follows: Wolinella greater than or equal to Salmonella greater than A . a . greater than B . intermedius greater than or equal to B . gingivalis . These findings demonstrate that LPS preparations from suspected periodontal pathogens are capable of stimulating PGE2 release from human monocytes . The high potency and prolonged stimulation of PGE2 release with Wolinella LPS suggests unusual toxic properties that may exert a greater influence in the pathogenesis of destructive periodontal diseases.

Mutat Res, 1988 Oct, 206(2), 247 - 59
Evaluation of azo food dyes for mutagenicity and inhibition of mutagenicity by methods using Salmonella typhimurium; Prival MJ et al.; The mutagenicity of 4 azo dyes (FD&C Yellow No . 5, FD&C Yellow No . 6, FD&C Red No . 40 and amaranth) that are widely used to color food has been evaluated . 4 different methods were used: (1) the standard Ames plate-incorporation assay performed directly on the dyes in the absence of S9 and in the presence of rat- or hamster-liver S9; (2) application of the standard plate assay to ether extracts of aqueous solutions of the dyes; (3) a variant of the standard assay, using hamster liver S9, preincubation, flavin mononucleotide (FMN) and other modifications designed to facilitate azo reduction; and (4) reduction of the dyes with sodium dithionite, followed by ether extraction and the standard plate assay . Assays that include chemical reduction (methods 3 and 4) were included because azo compounds ingested orally are reduced in the intestine with the release of free aromatic amines . No mutagenic activity was seen for any of the azo dyes tested by using the standard Ames plate assay (method 1) . Ether extracts of some samples of FD&C Yellow No . 6, FD&C Red No . 40 and amaranth were active (method 2), but only at high doses, generally 250 mg-equivalents or more per plate . These results indicate the presence of low levels of ether-extractable mutagenic impurities . The FMN preincubation assay (method 3) gave negative results for all dye samples tested . Most batches of FD&C Red No . 40 tested had mutagenic activity that was detectable when the ether extract of less than 1 mg of dithionite-reduced dye was plated in the presence of S9 (method 4) . This finding implies that an impurity in these samples of FD&C Red No . 40 can be reduced to yield an ether-extractable mutagen . Dithionite-reduced samples of FD&C Yellow No . 6 and amaranth showed ether-extractable mutagenic activity only at much higher doses than those at which activity was seen with most dithionite-reduced samples of FD&C Red No . 40 (method 4) . FD&C Yellow No . 5 showed no mutagenic activity with this method . Mutagenic activity was not detected when FD&C Red No . 40 was tested by using the azo reduction preincubation assay with FMN (method 3).(ABSTRACT TRUNCATED AT 400 WORDS)

Mutat Res, 1988 Oct, 206(2), 235 - 8
Evaluation of the mutagenic activity of some phenanthroisoquinolines in Salmonella typhimurium; Tanga MJ et al.; The mutagenic activity of 3 aza-polycyclic aromatic hydrocarbons, which are suspected of being environmental pollutants, was assessed using the Salmonella assay . The compounds tested were phenanthro{9,10-g}isoquinoline, phenanthro{2,3-h}isoquinoline, and phenanthro{3,2-h}isoquinoline . None of the compound was mutagenic in the absence of S9, but all were mutagenic in the presence of S9.

Mutat Res, 1988 Oct, 206(2), 221 - 5
Antimutagenic effects of several subfractions of extract from wheat sprout toward benzo{a}pyrene-induced mutagenicity in strain TA98 of Salmonella typhimurium; Peryt B et al.; The aqueous extract from wheat sprouts contains some antimutagenic factor(s) . The factor(s) abolish(es) the activity of aryl hydrocarbon (benzo{a}pyrene) hydroxylase (AHH) in the S9 fraction from Aroclor-treated rat livers and also inhibit(s) the mutagenic activity of benzo{a}pyrene (B(a)P) in the Ames test . The extract (fraction S30) was subjected to initial fractionation by thermal treatment, 3 24-h cycles of dialysis and ultrafiltration . The antigenotoxic activity of fraction S30 amounted to 98% and was unchanged by thermal treatment (100 degrees C, 10 min) . Both the dialysate and the dialysis fluid inhibited the mutagenic effect of B(a)P by 48.4 and 48% respectively . The microsomal subfraction inhibited the mutagenicity only in 10%, and the postmicrosomal subfraction in 68% . It is concluded that the extract from wheat sprouts contains at least 2 heat-resistant compounds (or groups of compounds) located within the cell cytosol and showing antimutagenic activity: one group is of low molecular weight and another of high MW . Alternatively, low-molecular compounds could either be free or bound to high-molecular compound(s).

Mutat Res, 1988 Oct, 206(2), 201 - 8
The mutagenic potencies of plant extracts containing quercetin in Salmonella typhimurium TA98 and TA100; Schimmer O et al.; Four commercial ethanolic plant extracts, Tinctura Alchemillae, Extractum Crataegi, Extractum Myrtilli and Tinctura Hyperici, were tested for their mutagenicity in Salmonella typhimurium TA98 and TA100 with and without S9 mix obtained from rats pretreated with phenobarbital . The extracts studied differed greatly in their mutagenic potencies but exhibited a very similar mutation pattern in which the strongest effect was always seen in tester strain TA98 with S9 mix . Simultaneously we investigated the extracts for the presence of quercetin and kaempferol . Only quercetin was detected in small amounts by thin-layer chromatography (TLC) . The fractions containing quercetin were separated and collected using a Sephadex LH-20 column . Two different methods were employed to estimate the amount of quercetin in the extracts: a colorimetric assay developed by Christ and Muller, and a complexometric method by Belikov . The quercetin concentrations ranged between 2 mg (Tinctura Alchemilla) and 89 mg (Tinctura Hyperici) per 100 g of extract . We suggest that the mutagenicity of the 4 plant extracts is mainly due to the presence of quercetin for the following reasons: (1) all the plant extracts exhibit a mutation pattern which is very similar to that of quercetin, (2) the mutagenic potential of the extracts correlates well with their quercetin content, considering the fact that plant extracts are very complex mixtures often containing toxic or antimutagenic compounds.

What Is Cell Biology?, What Is Yeast?, What Is Biofilter?, What Is Botulism?, What Is Water Purification?, s, Bacterium, o, Microbiology, n, Microorganisms, n, Microbes, o, Bacteriology, a, Acinetobacter, i, Beta lactamase, s, Yeasts, n, Lactobacillus, s, Enterococci, e, S. cerevisiae, i, S. cerevisiae, a, Streptococcal, s, Escherichia coli, e, Staphylococcus aureus, o, Fermentations, n, Prokaryotes, o, Staphylococcus, c, Fermentations, n, Morganella, n, Antimicrobial, a, Sepsis, e, Klebsiella, s, Escherichia coli, i, Streptococcal, o, Cryptococci

Scientific Publications - Work Done by Microbiology Reader Bioscreen C
Agricultural Microbiology Anaerobic Microbiology Antimicrobial Susceptibility Artificial Atmosphere Bioassay of Antibiotics Biofilm Microbiology Bioreactor Technology Biotechnology Cell Biology Clinical Microbiology Environmental Microbiology Experiments with Yeast	Fermentation Food Microbiology Functional Genomics Gene Technology Growth Media Development Growth Rate and Lag Time Industrial Microbiology Medical/Pharmaceutical Field Microbiological Assay Microbiological Research Microbiology of Cosmetics go to a specific theme...	Military Microbiology Molecular Microbiology Mutagenicity and Genotoxicity Oral Microbiology Patents Postantibiotic Studies Soil Microbiology Spore Microbiology Veterinary Microbiology Waste/Wastewater Treatment Water Microbiology Wine Microbiology

� 2005 Transgalactic Ltd (manufacturer of Bioscreen C software) | Privacy Statement | P.O. Box 1393, 00101 Helsinki, Finland, phone: +358 9 85172920, fax: +358 9 8749481, e-mail: microbiology@bionewsonline.com

Last modified: May 25, 2005