Zentralbl Bakteriol, 1993 Apr, 278(2-3), 383 - 95 The cellular immune response against Yersinia enterocolitica in different inbred strains of mice: evidence for an important role of T lymphocytes; Autenrieth IB et al.; Resistance of mice against infection with Yersinia enterocolitica has been shown to be related neither to the Ity locus coding for resistance against infection with Salmonella typhimurium and other pathogens nor to the H-2 locus . From other mouse infection models, e.g., murine leishmaniasis, there is evidence that a different T cell-dependent regulation of the host immune response in various inbred strains of mice determines the susceptibility to the infectious agent . However, until recently, little was known about the cellular immune response against Y . enterocolitica . Thus, in a first approach we used the highly virulent Y . enterocolitica strain WA of serotype O:8 and different inbred strains of mice (C57 BL/6, Balb/c and athymic T cell-deficient C57 BL/6 nude mice) to investigate the cell-mediated immunity against parenteral infection . Comparison of the median lethal dose and of the net-bacterial growth in the spleens of infected mice indicated that Balb/c mice could be considered as Yersinia-susceptible whereas C57 BL/6 mice were relatively resistant . However, in contrast to normal C57 BL/6, athymic T cell-deficient C57 BL/6 nude mice have proved to be highly susceptible to Yersinia infection suggesting that T cells are required for the elimination of the pathogen . This conclusion was supported by histomorphological and immunohistological results indicating that T lymphocytes were present in Yersinia-induced tissue lesions . Moreover, the adoptive transfer of Yersinia-specific T cell lines and clones into naive animals mediated significant protection against the pathogen in both Yersinia-resistant C57 BL/6 and in Yersinia-susceptible Balb/c mice . These findings emphasize an important role of T lymphocytes in the host response against Y . enterocolitica infection. Infect Agents Dis, 1993 Apr, 2(2), 55 - 73 New perspectives in vaccine development: mucosal immunity to infections; McGhee JR et al.; In this review, we focus on six key areas currently receiving attention in the mucosal immune system . These six areas are of considerable importance for development of vaccines . They are (a) the necessity to understand the unique features of the mucosal immune system; (b) the possibility that the common mucosal immune system may contain distinct compartments; (c) differences in antigen uptake and in types of antigen-presenting cells in mucosal inductive and effector sites; (d) more careful consideration of mucosal memory in vaccine development; (e) recent studies, which show that oral vaccines induce T-helper (Th)-cell subsets that regulate mucosal IgA responses; and (f) the mechanisms whereby mucosal S-IgA and T cells provide mucosal immune protection . An example of the above suffices to illustrate why the selected areas are of importance in vaccine development . Oral immunization preferentially induces type 2 Th (Th2) cell responses that directly correlate with antigen-specific IgA responses in mucosal effector sites . It is likely that activated, antigen-specific Th2 cells that are induced in Peyer's patches are continuously supplied to mucosal effector sites for regulation of IgA responses . These Th2 cells are producing cytokines such as interleukin (IL)-5 and IL-6 and these cytokines may direct antigen-specific surface IgA-positive B cells to become IgA-producing plasma cells . Nevertheless, additional studies will be required to establish that IgA responses to T-cell-dependent antigens depend on Th2 cell-derived help . What are the implications of these studies for current oral vaccines, including novel antigen delivery systems? The most obvious would be that vaccines should be optimized for induction of Th2-cell responses in IgA inductive sites such as the gut-associated lymphoreticular tissues . It is now clear that induction of Th2-type responses in both mucosal inductive and mucosal effector sites are essential for oral vaccines to induce S-IgA responses . However, antigens delivered by live vectors such as Salmonella typhimurium in the murine system and S . typhi in humans must consider T-cell responses induced against a live vector in addition to the inserted recombinant antigen . In this regard, it has been shown that these microorganisms induce cell-mediated immunity responses that largely result from Th1-type cells.(ABSTRACT TRUNCATED AT 400 WORDS) J Immunol, 1993 Apr 1, 150(7), 2869 - 84 Comparison of antigen presentation of influenza A nucleoprotein expressed in attenuated AroA- Salmonella typhimurium with that of live virus; Brett SJ et al.; Rationally attenuated strains of Salmonella expressing foreign proteins represent a potentially important vaccine delivery system . The characteristics of Ag presentation of influenza nucleoprotein expressed in an AroA- strain of Salmonella typhimurium (SL3262-pNP-2) have therefore been compared with those of soluble purified nucleoprotein (NP) and infectious influenza virus . This represents three distinct modes of internalization of the same protein into APC . Human monocytes and the monocytic leukemia cell line THP-1 infected with SL3261-pNP-2 were found to present several different epitopes from NP to human CD4+ class II-restricted T lymphocytes . Ag presentation to these T cell clones was enhanced by pretreatment of THP-1 cells with IFN-gamma but not TNF-alpha . Bacterial phagocytosis and Ag presentation of NP were increased after opsonization of Salmonella with immune serum . Macrophages infected with SL3261-pNP-2 were unable to present NP to class I-restricted T cells . In contrast, cells infected with live influenza virus, although recognized by NP-specific class I-restricted CTL, were inefficiently recognized by NP-specific class II-restricted T cells . Ag presentation to CD4+ T cell clones by monocytes of SL3261-pNP-2, purified recombinant NP, and live influenza virus, but not the synthetic peptide 206-229, was inhibited by chloroquine and the protease inhibitors pepstatin A and leupeptin, suggesting that the major route of processing in each case was via the exogenous pathway . T cell recognition of NP via all of these Ag delivery systems was also abrogated by cycloheximide and brefeldin A treatment, indicating a requirement for recently synthesized MHC class II molecules in presentation of whole NP after processing but not for the corresponding synthetic peptide. J Immunol, 1993 Apr 1, 150(7), 2737 - 45 Comparative in vitro analysis of proliferation, Ig secretion, and Ig class switching by murine marginal zone and follicular B cells; Snapper CM et al.; We have previously demonstrated that activation of murine B cells by dextran-conjugated anti-IgD antibodies may serve as a polyclonal, in vitro model system for studying immune responses to T cell-independent type 2 (TI-2) Ag, as exemplified by the bacterial polysaccharides . Because in vivo Ig responses to TI-2 Ag are mediated primarily by B cells resident in the splenic marginal zone, we wished to determine whether this reflected an intrinsic difference in the responsiveness of marginal zone B cells (MZB) compared with follicular B cells (FB) to this class of Ag . In this report we demonstrate that highly purified MZB, isolated by electronic cell sorting, exhibit a lower proliferative response in vitro in response to unconjugated anti-Ig antibody as well as to dextran- or Sepharose-conjugated anti-IgM or anti-IgD antibodies, whereas they proliferate equal to or better than FB when stimulated by other B cell mitogens including LPS, Salmonella typhimurium mitogen, or anti-CD3-activated CD4+ Th2 cell clone . Despite the different proliferative responses of MZB and FB induced by anti-Ig, Ag receptor cross-linkage stimulates comparable increases in intracellular free calcium concentrations in both of these B cell populations . Furthermore, MZB secrete Ig and undergo Ig isotype switching to a comparable degree, relative to FB, in response to both T cell-dependent and T cell-independent stimuli . This suggests that the compartmentalization of TI-2 responses to the splenic marginal zone rather than the follicular zone reflects something other than the intrinsic responsiveness of the B cells from these two sites. Infect Immun, 1993 Apr, 61(4), 1222 - 31 Oral vaccination of calves with an aromatic-dependent Salmonella dublin (O9,12) hybrid expressing O4,12 protects against S . dublin (O9,12) but not against Salmonella typhimurium (O4,5,12); Segall T et al.; Three groups of six calves each, 5 to 7 weeks old, were orally vaccinated with the live aromatic-dependent delta aroA Salmonella dublin (O9,12) hybrid strain SL7103 with the O4,12-specifying rfb gene cluster from Salmonella typhimurium . SL7103 was given in three weekly doses, increasing from 2 x 10(9) to 1 x 10(11) bacteria per ml, was well tolerated, and caused mild, short-term temperature increases which diminished with each immunization . The strain was shed for up to 1 week . Strain SL7103 elicited significant (P < 0.001) and equal anti-S . dublin and -S . typhimurium lipopolysaccharide serum antibody responses and skin delayed-type hypersensitivity immune responses . Six vaccinated calves orally challenged with 10(10) CFU (equivalent to 1,000 50% lethal doses) of the virulent parent strain S . dublin SVA47 were protected and experienced only transient fever and mild mucoid diarrhea . However, six vaccinated calves orally challenged with 3 x 10(9) CFU and another six challenged with 3 x 10(8) CFU (equivalent to 1,000 50% lethal doses) of the virulent S . typhimurium SVA44 became bacteremic with a profuse hemorrhagic diarrhea and had to be sacrificed within 2 to 7 days . The results suggest that the S . typhimurium antilipopolysaccharide immunity was insufficient to provide a solid protective efficacy against oral S . typhimurium infection . The immunohistopathological examination revealed that S . typhimurium SVA44 could be found in all layers of the intestinal mucosa and the lymphatic tissues of the Peyer's patches . In contrast, S . dublin SVA47 was found predominantly in the columnar enterocytes of the jejunum and ileum and the follicle-associated epithelium over the Peyer's patches . In addition, SVA47 was found in the glandular tissues of the duodenal and tonsillar areas and in the lungs . This suggests that the S . typhimurium and S . dublin strains have different virulence traits determining their tissue localization and dissemination. Infect Immun, 1993 Apr, 61(4), 1211 - 21 Antibody response and protection against challenge in mice vaccinated intraperitoneally with a live aroA O4-O9 hybrid Salmonella dublin strain; Lindberg AA et al.; An auxotrophic Salmonella dublin (O9,12) strain, SL5631, with a deletion affecting gene aroA, was made into a partial diploid expressing the rfb (O-antigen-repeat-unit-specifying) gene cluster of Salmonella typhimurium (O4,12) . By use of O4- and O9-specific antisera in indirect immunofluorescence assays, the resulting hybrid SL7103 was shown to express both the O4- and O9-antigen epitopes in the same bacterium . Qualitative and quantitative sugar analyses by gas-liquid chromatography on peralditol acetates of phenol-water-extracted lipopolysaccharides showed that the S . dublin and S . typhimurium repeating units (estimated on the basis of their tyvelose and abequose contents, respectively) were present in approximately equimolar amounts . The SL7103 hybrid auxotroph was avirulent when given intraperitoneally to NMRI mice in a dose of 10(8) CFU and elicited a protective immunity against intraperitoneal challenge with either virulent S . dublin (50% lethal dose of ca . 1.5 x 10(4) CFU versus < 1 x 10(1) CFU in nonimmunized mice) or virulent S . typhimurium (50% lethal dose of ca . 1 x 10(5) versus < 1 x 10(1) CFU in nonimmunized mice) . Compared with the protection elicited in homologous systems (S . dublin SL5631 against S . dublin and S . typhimurium SL1479 against S . typhimurium), the protective efficacy of the hybrid was reduced approximately 70-fold against S . dublin challenge and 100-fold against S . typhimurium challenge . Vaccination with S . typhimurium SL1479 conferred no protection against S . dublin challenge, and vaccination with S . dublin SL5631 conferred no protection against S . typhimurium challenge . The protection elicited by the hybrid strain SL7103 is supposed to be mainly a consequence of serum antibodies directed against the immunodominant O4 and O9 epitopes. Mutat Res, 1993 Apr, 301(4), 213 - 22 Mutagenicity of alkylhydrazine oxalates in Salmonella typhimurium TA100 and TA102 demonstrated by modifying the growth conditions of the bacteria; Matsushita H Jr et al.; Alkylhydrazines are important carcinogens . However, they show generally only weak mutagenicity and the activities reported from different laboratories are contradictory . We have developed a sensitive method to detect the mutagenicity of alkylhydrazines . The method is based on a modified preculturing procedure in the Ames test, the emphasis in the modification being a change in the growth period of tester strains . The optimal growth periods were found to be 11 h in Salmonella typhimurium TA100 and 5 h in Salmonella typhimurium TA102 . We tested the mutagenic activity of 12 alkylhydrazines; 1,2-dimethylhydrazine, 1,2-diethylhydrazine, 1,2-dipropylhydrazine, 1,2-dibutylhydrazine, 1,1-dimethylhydrazine, 1,1-diethylhydrazine, 1,1-dipropylhydrazine, 1,1-dibutylhydrazine, methylhydrazine, ethylhydrazine, propylhydrazine and butylhydrazine . All 12 alkylhydrazines were clearly mutagenic in Salmonella typhimurium TA102, and 10 hydrazines were mutagenic in Salmonella typhimurium TA100, both in the absence of S9 mix . The mutagenicity was inhibited by the addition of S9 mix or bovine serum albumin . This suggests deactivation of the mutagens by proteins. Mutat Res, 1993 Apr, 299(2), 85 - 93 Quantitative structure-activity relationships for the mutagenicity of propylene oxides with Salmonella; Hooberman BH et al.; A quantitative structure-activity relationship approach was used to investigate the mutagenicity of a series of seventeen-monosubstituted propylene oxides in Salmonella typhimurium strains TA100 and TA1535 . Mutagenicity in strain TA100, using a liquid suspension assay, was found to correlate with chemical reactivity, as measured by the rates of reaction with two model bionucleophiles, nicotinamide and 4-(4-nitrobenzyl)pyridine . However, since the reactivity of three of the epoxides did not correlate to their Taft sigma * values, as a measure of the electronic effects of substituent groups, neither was their mutagenicity predicted by this substituent constant . The relative mutagenicity for the propylene oxides was different in the liquid suspension assay than that determined by the standard plate incorporation assay and also differed between the two bacterial strains . The assay differences were attributed to epoxide stability . The differences between strains was observed to be due to the response of the error-prone repair system, found only in TA100, to the stronger alkylating agents. Mutat Res, 1993 Apr, 299(2), 111 - 20 Characterization of stable high molecular weight mutagenic product(s) of plant-activated m-phenylenediamine; Seo KY et al.; Monocyclic aromatic amines are environmental contaminants and many are promutagens and procarcinogens . Cultured tobacco cells, strain TX1, activated m-phenylenediamine into a frameshift mutagen that reverted the hisD3052 allele in Salmonella typhimurium strains TA98 and YG1024 . However, the plant-activated products were refractory in strain TA98/1,8-DNP6 . This indicated that these plant-activated products were substrates for bacterial acetyl-CoA: N-hydroxyarylamine O-acetyltransferase . A stable, high molecular weight (> 300 kDa) proximal mutagen was isolated by molecular ultrafiltration membranes . No parent compound was associated with the isolated mutagenic fraction . The high molecular weight fraction induced mutation in S . typhimurium strains TA98, YG1021 and YG1024 . From these data we propose a model for the plant-activation of aromatic amine promutagens. Genetika, 1993 Mar, 29(3), 423 - 9 {The nature of the emergence of His+-revertants in Salmonella typhimurium}; Gizatullin FSh et al.; The His(-)-->His+ spontaneous reversion of the Salmonella typhimurium alleles hisD3052 and hisG46 was studied . The expected jackpot distribution of His+ revertants was not observed in the fluctuation tests . The experimental distributions were close to Poisson . It was also shown that the mean number of His+ reversion events and the mean number of revertants per plate were similar . These data demonstrate that the His+ reversion occurred under the influence of histidine starvation . At the same time, kanamycin resistant mutants had the jackpot distribution . Selection for His+ revertants did not increase the Kans-->Kanr mutations. Chem Biol Interact, 1993 Mar, 86(3), 229 - 54 Mechanism of genotoxicity and electron density distribution by NMR of 5-nitro-3-thiophenecarboxamides, a novel group of direct-acting mutagens in Salmonella typhimurium; Hrelia P et al.; The mutagenic activity of 23 5-nitro-3-thiophenecarboxanilides and of 5-nitro-3-thiophenecarboxamide, the prototype, (NTCAs) have been evaluated in the Ames test on Salmonella typhimurium strains TA100 ad TA98 with and without metabolic activation . Effects of different substituents (electron-donating and electron-withdrawing) were studied to evaluate structural features that affect the metabolism and the bacterial mutagenic potency . All the derivatives were direct-acting mutagens, the mutagenic potency ranging from 0.7 to 142 revertants (rev.)/nmol in TA100 and from 0.09 to 68 rev./nmol in TA98 strain . Results obtained with strains TA98NR and TA98/1,8-DNP6 indicated that the mutagenic activity was largely dependent on bacterial nitroreductase, whereas the O-acetylation step was not critical for mutagenic potency . Superoxide (O2-.) and hydroxyl (OH.) scavengers as well as other radical scavengers and enzymes inhibited NTCAs mutagenicity to different extents . In particular, O2- . seemed to be involved in NTCAs mutagenicity, showing a free radical pathway for NTCA metabolism . {1H}- and {13C}NMR data indicated that the effects of different substituents on genotoxicity are probably not exerted on the electron density distribution . The importance of factors such as extent of nitration, reduction potential, orientation of nitrosubstituent and planarity of the molecule are discussed. Mol Gen Genet, 1993 Mar, 237(3), 429 - 38 Toxicity of and mutagenesis by chlorate are independent of nitrate reductase activity in Chlamydomonas reinhardtii; Prieto R et al.; Spontaneous chlorate-resistant (CR) mutants have been isolated from Chlamydomonas reinhardtii wild-type strains . Most of them, 244, were able to grow on nitrate minimal medium, but 23 were not . Genetic and in vivo complementation analyses of this latter group of mutants indicated that they were defective either at the regulatory locus nit-2, or at the nitrate reductase (NR) locus nit-1, or at very closely linked loci . Some of these nit-1 or nit-2 mutants were also defective in pathways not directly related to nitrate assimilation, such as those of amino acids and purines . Chlorate treatment of wild-type cells resulted in both a decrease in cell survival and an increase in mutant cells resistant to a number of different chemicals (chlorate, methylammonium, sulphanilamide, arsenate, and streptomycin) . The toxic and mutagenic effects of chlorate in minimal medium were not found when cells were grown either in darkness or in the presence of ammonium, conditions under which nitrate uptake is drastically inhibited . Chlorate was also able to induce reversion of nit- mutants of C . reinhardtii, but failed to produce His+ revertants or Arar mutants in the BA-13 strain of Salmonella typhimurium . In contrast, chlorate treatment induced mutagenesis in strain E1F1 of the phototrophic bacterium Rhodobacter capsulatus . Genetic analyses of nitrate reductase-deficient CR mutants of C . reinhardtii revealed two types of CR, to low (1.5 mM) and high (15 mM) chlorate concentrations . These two traits were recessive in heterozygous diploids and segregated in genetic crosses independently of each other and of the nit-1 and nit-2 loci . Three hcr loci and four lcr loci mediating resistance to high (HC) and low (LC) concentrations of chlorate were identified . Mutations at the nit-2 locus, and deletions of a putative locus for nitrate transport were always epistatic to mutations responsible for resistance to either LC or HC . In both nit+ and nit- chlorate-sensitive (CS) strains, nitrate and nitrite gave protection from the toxic effect of chlorate . Our data indicate that in C . reinhardtii chlorate toxicity is primarily dependent on the nitrate transport system and independent of the existence of an active NR enzyme . At least seven loci unrelated to the nitrate assimilation pathway and mediating CR are thought to control indirectly the efficiency of the nitrate transporter for chlorate transport . In addition, chlorate appears to be a mutagen capable of inducing a wide range of mutations unrelated to the nitrate assimilation pathway. Mol Microbiol, 1993 Mar, 7(6), 883 - 91 Organization of Lrp-binding sites upstream of ilvIH in Salmonella typhimurium; Wang Q et al.; Lrp, a major regulatory protein in Escherichia coli, controls the expression of numerous operons, including ilvIH . Lrp binds to six sites upstream of ilvIH, and Lrp binding is required for ilvIH expression . We show here that an Lrp-like protein is also present in Salmonella typhimurium . This protein can bind both E . coli and S . typhimurium ilvIH DNA, as can E . coli Lrp . Methidiumpropyl-EDTA footprinting studies were performed with purified E . coli Lrp and S . typhimurium ilvIH DNA . Six binding sites were defined, three of them being similar to corresponding sites in E . coli, and three being organized differently . A consensus derived from six S . typhimurium sites is compatible with that derived from a similar analysis of E . coli sequences. Mol Microbiol, 1993 Mar, 7(6), 825 - 30 Molecular analysis of spv virulence genes of the Salmonella virulence plasmids; Gulig PA et al.; Genes on an 8 kb region common to the virulence plasmids of several serovars of Salmonella are sufficient to replace the entire plasmid in enabling systemic infection in animal models . This virulence region encompasses five genes which previously have been designated with different names from each investigating laboratory . A common nomenclature has been devised for the five genes, i.e . spv for salmonella plasmid virulence . The first gene, spvR, encodes a positive activator for the following four genes, spvABCD . DNA sequence analysis of the spv genes from Salmonella typhimurium, Salmonella dublin, and Salmonella choleraesuis demonstrated extremely high conservation of the DNA and amino acid sequences . The spv genes are induced at stationary phase and in carbon-poor media, and optimal expression is dependent on the katF locus . The virulence functions of the spv genes are not known, but these genes may increase the growth rate of salmonellae in host cells and affect the interaction of salmonellae with the host immune system. Mutagenesis, 1993 Mar, 8(2), 127 - 31 Mutagenic and lethal effects of halogenated methanes in the Ara test of Salmonella typhimurium: quantitative relationship with chemical reactivity; Roldan-Arjona T et al.; The mutagenic and lethal effects of nine halogenated methanes (CCl4, carbon tetrachloride; CHCl3, chloroform; CH2Cl2, dichloromethane; CBr4, carbon tetrachloride; CHBr3, bromoform; CH2Br2, dibromomethane; CI4, carbon tetraiodide; CHI3, iodoform; and CH2I2, diiodomethane) have been investigated with the Ara forward-mutation assay of Salmonella typhimurium . Five substances (CH2Cl2, CBr4, CH2Br2, CHI3 and CH2I2) gave clear mutagenic responses . In all these cases the mutagenicity diminished in the presence of mammalian metabolic activation (S9 mixture) . Two halomethanes (CCl4 and CHBr3) were classified as 'questionable' mutagens since they did not double the spontaneous value although a dose-response curve was obtained . All halomethanes tested exerted a lethal effect . A high concordance was found between lethality and chemical reactivity, as expected from the type and number of halogenated substituents . Compounds with equal numbers of substituents were lethal in the order I > Br > Cl . Additionally, the lethality of compounds with identical halogen substituents increased by successive halogenations . No such concordances were observed with respect to mutagenic activity . Structure-activity quantitative relationships were investigated by using the previously reported values of the polarographic half-wave reduction potential (-E1/2), a physicochemical parameter related to the energy required to put an electron into the lowest unoccupied molecular orbital . The lethality, quantified as LD37, correlated highly with the -E1/2 values for the nine halogenated compounds (r = -0.955 P < 0.001) . These data suggest that halomethanes which are reduced easily will induce higher lethality than those with low reduction potential, in agreement with the predicted effects on lipid peroxidation and hepatotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS) Carcinogenesis, 1993 Mar, 14(3), 441 - 50 Vinyl carbamate epoxide, a major strong electrophilic, mutagenic and carcinogenic metabolite of vinyl carbamate and ethyl carbamate (urethane); Park KK et al.; Vinyl carbamate epoxide (VCO) was found to possess strong electrophilic, mutagenic and carcinogenic activities . It reacted with water at 37 degrees C and pH 7.4 (phosphate buffer) to form glycolaldehyde and several related reducing compounds; none of these products were mutagenic for Salmonella typhimurium TA1535 . Under these conditions VCO had a half-life (determined chemically and mutagenically) of approximately 10.5 min . This half-life was progressively lowered by increasing concentrations of chloride ion (liver, serum and isotonic levels) . This ion reacted with VCO to form chloroacetaldehyde . VCO also reacted with other nucleophiles such as glutathione, DNA and its constituent guanine and adenine bases . The purine adducts formed by VCO in DNA in vitro and in vivo were released by weak acid treatment and consisted of 7-(2'-oxoethyl)guanine and N2,3-ethenoguanine as major products with 1,N6-ethenoadenine as a minor product . VCO was a strong direct mutagen in Salmonella typhimurium TA1535 and TA100 but was only weakly active in the TA98 mutant . VCO was a stronger initiator of carcinogenesis in the skin of CD-1 mice and in the liver of infant male B6C3F1 mice than its metabolic precursors vinyl carbamate (VC) and ethyl carbamate (EC) . Unlike VC and EC, VCO was a strong complete carcinogen in the skin of CD-1 mice and induced papillomas and carcinomas following repetitive administration of sub-ulcerogenic doses . VCO also exhibited some carcinogenic activity in the lungs of mice and in the s.c . and mammary tissue of female Sprague-Dawley rats . These data and those from other recent studies support the conclusion that VCO is a major strong electrophilic, mutagenic and carcinogenic metabolite of EC and VC in the mouse. J Gen Virol, 1993 Mar, 74 ( Pt 3), 453 - 8 Expression of the G glycoprotein gene of human respiratory syncytial virus in Salmonella typhimurium; Martin-Gallardo A et al.; The attachment protein, G, of human respiratory syncytial virus (RSV) is an M(r) 84K to 90K species which has a high content of N-linked and O-linked carbohydrates . The unglycosylated form of this protein was expressed by inserting a full-length cDNA copy of the mRNA from the A2 strain of RSV into a prokaryotic expression vector under the control of the lambda PL promoter . Salmonella typhimurium cells transformed with the G-containing plasmid synthesized a protein of M(r) 40,000 that specifically reacted with polyclonal and two neutralizing monoclonal antibodies raised against the native RSV G glycoprotein . Recombinant G protein was purified by immunoaffinity chromatography using a neutralizing monoclonal antibody . Cotton rats immunized with the recombinant G protein produced serum antibodies to the G glycoprotein that neutralized RSV in vitro . The study demonstrates that the G protein of RSV can be expressed in bacteria and that at least one neutralizing epitope is not structurally dependent on carbohydrates. J Bacteriol, 1993 Mar, 175(5), 1524 - 7 The rfaS gene, which is involved in production of a rough form of lipopolysaccharide core in Escherichia coli K-12, is not present in the rfa cluster of Salmonella typhimurium LT2; Klena JD et al.; Partial sequencing of the rfa cluster of Salmonella typhimurium LT2 indicated a region of 336 bp between rfaP and rfaB in the site occupied by the rfaS gene in Escherichia coli K-12 . This region does not contain a functional rfaS gene, although DNA analysis suggests that the region may have contained an ancestral gene . This conclusion that S . typhimurium LT2 lacks rfaS is supported by its lipopolysaccharide (LPS) gel phenotype, since LT2 does not make the lipooligosaccharide band characteristic of LPS from smooth strains of E . coli K-12. Eur J Biochem, 1993 Mar 1, 212(2), 431 - 40 Purification and characterization of anthranilate synthase from Catharanthus roseus; Poulsen C et al.; Anthranilate synthase (EC 4.1.3.27) has been purified from cell cultures of Catharanthus roseus by poly(ethylene glycol) precipitation/fractionation and subsequent separation by anion exchange on Q-Sepharose, Orange A dye chromatography, Mono Q anion-exchange chromatography and Superose 6 gel filtration . By analogy to anthranilate synthases from other sources it does look like the enzyme is a tetramer composed of two large and two small subunits, with molecular mass 67 and 25.5 +/- 0.5 kDa, respectively . The molecular mass determined by gel filtration was 143 +/- 5 kDa . The enzyme had a pI of 5.1 determined by chromatofocusing . The pH optimum was between pH 7.5 and pH 8.3, but the type of buffer used affected the results . The enzyme could utilize NH4+ as ammonium donor instead of glutamine . The enzyme showed normal Michaelis-Menten kinetics with respect to the substrates L-glutamine and chorismate, and the cofactor Mg2+, Km values for L-glutamine was determined to be 0.37 +/- 0.05 mM, for chorismate 67 +/- 3 microM, and for MgCl2 0.26 +/- 0.03 mM respectively . Anthranilate synthase was inhibited by L-tryptophan, tryptamine and D-tryptophan (with L-tryptophan being the best inhibitor) . The enzyme was allosterically regulated showing positive cooperatively of chorismate binding at higher concentrations of tryptophan . For a tryptophan concentration of 20 microM the Hill coefficient was determined to be 2 . The tryptophan binding sites showed positive cooperatively for higher concentrations of chorismate . The purified enzyme did not contain anthranilate-5-phosphoribosylpyrophosphate phosphoribosyltransferase activity and is thus not of the same type as the well characterized Salmonella typhimurium anthranilate synthase/phosphoribosyl pyrophosphate transferase bifunctional type. Am Rev Respir Dis, 1993 Mar, 147(3), 658 - 63 Pulmonary complications of human immunodeficiency virus infection in Bujumbura, Burundi; Kamanfu G et al.; To determine the types of pulmonary disease associated with human immunodeficiency virus (HIV) infection, we conducted a prospective study of 302 consecutive patients admitted for acute respiratory disease to a university hospital in Bujumbura, Burundi . Diagnoses were made according to well-defined criteria . Of the total, 222 patients (73.5%) were HIV seropositive, with women younger than men . Features suggestive of underlying HIV infection were the clinical findings of oral thrush, peripheral lymphadenopathy, or herpes zoster and the radiographic abnormalities of hilar-mediastinal adenopathy or a reticulonodular infiltrate . Tuberculosis and community-acquired pneumonia occurred with approximately equal frequency in the HIV-seropositive and seronegative groups . Pneumocystis carinii pneumonia was diagnosed in 11 patients, all seropositive . Gram-negative bacteremia, especially Salmonella typhimurium, occurred in 23 seropositive patients (10.4%) . A total of 24 seropositive patients died during the initial hospitalization, and 11 others required readmission; no seronegative patients died or were rehospitalized . We conclude that HIV infection is a major risk factor for the development of acute respiratory diseases in adults of sufficient severity to require hospitalization in Bujumbura . In this Central African country, where exposure to virulent bacterial pathogens is ubiquitous, tuberculosis, pneumonia, and salmonellosis occur with much greater frequency than classic AIDS-defining opportunistic infections or malignancies. Infect Immun, 1993 Mar, 61(3), 823 - 9 T-cell-independent resistance to infection and generation of immunity to Francisella tularensis; Elkins KL et al.; The intraperitoneal 50% lethal dose (LD50) for Francisella tularensis LVS in both normal control heterozygote BALB/c nu/+ mice and BALB/c nu/nu mice was 2 x 10(0) . Both nu/+ and nu/nu mice given 10(7) LVS bacteria or more intradermally (i.d.) died, with a mean time to death of about 7 to 8 days . On the other hand, nu/+ mice given 10(6) LVS bacteria or less survived for more than 60 days and cleared systemic bacteria, while nu/nu mice given 10(6) LVS bacteria or less survived for more than 10 days but died between days 25 and 30 . Thus, the short-term (i.e., < 10-day) i.d . LD50 of both nu/nu and nu/+ mice was 3 x 10(6), but the long-term (i.e., > 10-day) i.d . LD50 of nu/nu mice was less than 7 x 10(0) . The short-term survival of i.d . infection was dependent on tumor necrosis factor and gamma interferon: treatment of nu/nu mice with anti-tumor necrosis factor or anti-gamma interferon at the time of i.d . infection resulted in death from infection 7 to 8 days later, whereas control infected nu/nu mice survived for 26 days . nu/nu mice infected with LVS i.d . generated LVS-specific serum antibodies, which were predominantly immunoglobulin M: titers peaked 7 days after i.d . infection but declined sharply by day 21, after which mice died . Surprisingly, nu/nu mice given 10(3) LVS bacteria i.d . became resistant to a lethal challenge (5,000 LD50s) of LVS intraperitoneally within 2 days after i.d . infection; nu/nu mice similarly infected with LVS i.d . and challenged with Salmonella typhimurium (10 LD50s) were not protected . nu/nu mice given nu/+ spleen cells intravenously as a source of mature T cells survived i.d . infection for more than 60 days and cleared bacteria . Taken together, these studies demonstrate that i.d . infection of nu/nu mice with LVS rapidly generates T-cell-independent, short-term, specific protective immunity against lethal challenge, but T lymphocytes are essential for long-term survival. Infect Immun, 1993 Mar, 61(3), 1004 - 15 Escherichia coli heat-labile toxin subunit B fusions with Streptococcus sobrinus antigens expressed by Salmonella typhimurium oral vaccine strains: importance of the linker for antigenicity and biological activities of the hybrid proteins; Jagusztyn-Krynicka EK et al.; A set of vectors possessing the genes for aspartate semialdehyde dehydrogenase (asd) and the B subunit of the heat-labile enterotoxin of Escherichia coli (LT-B) has been developed . These vectors allow operon or gene fusions of foreign gene epitopes at the C-terminal end of LT-B . Two groups of vectors have been constructed with and without leader sequences to facilitate placing of the foreign antigen in different cell compartments . Two Streptococcus sobrinus genes coding for principal colonization factors, surface protein antigen A (SpaA), and dextranase (Dex), have been fused into the 3' end of the LT-B gene . Resulting protein fusions of approximately 120 to 130 kDa are extremely well recognized by antibodies directed against both SpaA and Dex as well as against LT-B domains and retain the enzymatic activity of dextranase and the biological activity of LT-B in that they bind to GM1 gangliosides . Maximum antigenicity was obtained with the vector possessing an intervening linker of at least six amino acids with two proline residues . Some of the fusion proteins also exhibited another property of LT-B in that they were exported into the periplasm where they oligomerized . LT-B-SpaA and LT-B-Dex hybrid proteins are expressed stably and at a high level in avirulent Salmonella typhimurium vaccine strains which are being used to investigate their immunogenicity and types of induced immune responses . The fusion vectors will also be useful for production and purification of LT-B fusion antigens to be used and evaluated in other vaccine compositions. Mol Microbiol, 1993 Mar, 7(6), 933 - 6 Recombination-deficient mutants of Salmonella typhimurium are avirulent and sensitive to the oxidative burst of macrophages; Buchmeier NA et al.; Mutations in the genes recA and recBC were constructed in the virulent Salmonella typhimurium strain 14028s . Both the recA and recBC mutants were attenuated in mice . The mutants were also sensitive to killing by macrophages in vitro . The recombination mutants were no longer macrophage sensitive in a variant line of J774 macrophage-like cells that fail to generate superoxide . This suggests that repair of DNA damage by Salmonella is necessary for full virulence in vivo and that the oxidative burst of phagocytes is one source of such DNA damage. Genetics, 1993 Mar, 133(3), 449 - 54 Natural populations of Escherichia coli and Salmonella typhimurium harbor the same classes of insertion sequences; Bisercic M et al.; Despite their close phylogenetic relationship, Escherichia coli and Salmonella typhimurium were long considered as having distinct classes of transposable elements maintained by either host-related factors or very restricted gene exchange . In this study, genetically diverse collections of E . coli and S . typhimurium (subgroup I) were surveyed for the presence of several classes of insertion sequences by Southern blot analysis and the polymerase chain reaction . A majority of salmonellae contained IS1 or IS3, elements originally recovered from E . coli, while IS200, a Salmonella-specific element, was present in about 20% of the tested strains of E . coli . Based on restriction mapping, the extent of sequence divergence between copies of IS200 from E . coli and S . typhimurium is on the order of that observed in comparisons of chromosomally encoded genes from these taxa . This suggests that copies of IS200 have not been recently transferred between E . coli and S . typhimurium and that the element was present in the common ancestor to both species . IS200 is polymorphic within E . coli but homogeneous among isolates of S . typhimurium, providing evidence that these species might differ in their rates of transfer and turnover of insertion sequences. J Bacteriol, 1993 Mar, 175(5), 1457 - 66 Genetic structure and regulation of the cysG gene in Salmonella typhimurium; Goldman BS et al.; Siroheme, a cofactor of both sulfite and nitrite reductase in Salmonella typhimurium, requires the cysG gene for its synthesis . Three steps are required to synthesize siroheme from uroporphyrinogen III, the last common intermediate in the heme and siroheme pathways . All previously characterized cysG mutants were shown to be defective for the synthesis of cobalamin (B12), which shares a common precursor with siroheme . Since few cysG auxotrophs had been previously analyzed and since there is no evidence of siroheme mutants outside of the cysG region, we sought to expand the analysis of the region by isolating more mutations and studying the transcriptional regulation of the cysG gene using lacZ fusions . We isolated and analyzed 66 cysG auxotrophs . All were defective for both siroheme and cobalamin synthesis . Five exceptional mutants were partially defective for the synthesis of both and appear to be leaky . Complementation tests with tandem duplications suggest that the mutations causing the Cys auxotrophy affect only one cistron . The cysG gene is transcribed in a clockwise direction; this was demonstrated by a method that permits determining the orientation of two genes of unknown orientation provided their relative map order is known . The cysG gene was not part of the cysteine regulon, but had a substantial basal level of expression which was induced fivefold when cells were grown anaerobically on nitrite . Finally, we used Mud-generated duplications to genetically determine the organization of the cysG and nirB genes. Infect Immun, 1993 Mar, 61(3), 940 - 6 Isolation and characterization of a cloned Porphyromonas gingivalis hemagglutinin from an avirulent strain of Salmonella typhimurium; Dusek DM et al.; Identification of surface macromolecules of Porphyromonas gingivalis that act as virulence factors in periodontal disease has important implications for studying host-parasite interactions as well as for potential vaccine development . The objective of this study was to determine whether a cloned, P . gingivalis hemagglutinin gene could be expressed in an intact form in an avirulent Salmonella typhimurium vaccine construct and to characterize the recombinant protein . The recombinant protein was purified from the vaccine strain, characterized, and tested for biological activity as a competitive inhibitor of hemagglutination . Cells of S . typhimurium SL3261/pST7 grown in Luria broth were broken by sonic disruption and fractionated . The purified recombinant protein was found to inhibit hemagglutination of erythrocytes by whole P . gingivalis cells . The same purified protein was analyzed for its N-terminal amino acid sequence and amino acid composition and found to match that predicted from the nucleotide sequence of the cloned gene . These results indicate that a surface macromolecule of P . gingivalis can be expressed in an intact and biologically active form in a Salmonella carrier strain. Microb Pathog, 1993 Mar, 14(3), 217 - 27 Tumor necrosis factor-alpha mediates the early pathology in Salmonella infection of the gastrointestinal tract; Arnold JW et al.; Salmonella infection of the intestinal tract results in damage to the gut epithelium . While it is generally believed that bacteria and/or bacterial products account for this pathology, the role of host factors has not been explored . Using a ligated intestinal loop model, we investigated whether tumor necrosis factor-alpha (TNF-alpha) could contribute to the tissue pathology associated with Salmonella infection . Intestinal segments infected with Salmonella typhimurium had high levels of fluid secretion as early as 6 h post-bacterial infection . At this time point, low levels of TNF activity were also present in the fluid obtained from infected segments . At 20 h post-infection, high levels of TNF activity were present in fluids obtained from infected intestinal segments and was characterized as TNF-alpha by neutralization experiments using rabbit antisera to TNF-alpha . TNF-alpha production was further verified by Northern blot analysis using RNA obtained from cells eluted from the infected intestinal segments . In contrast, no TNF activity was found in fluid obtained from intestinal segments challenged with cholera toxin, which induces fluid secretion with little to no inflammatory response . Double labeling by in situ hybridization and immunocytochemistry revealed that macrophages in the lamina propria were producing the TNF-alpha mRNA . To investigate what role TNF-alpha might play in Salmonella-induced inflammation, intestinal segments were injected with recombinant mouse TNF-alpha (rTNF-alpha) or mice were pretreated with antibody to TNF-alpha or a control antibody prior to Salmonella infection . The histological profile of intestinal segments injected with rTNF-alpha appeared identical to segments infected with S . typhimurium . Further, pathology was completely eliminated in infected mice pretreated with antibody to TNF-alpha . These results document the production of TNF-alpha in the intestinal tract following S . typhimurium infection and show that the early pathology induced by Salmonella infection of the gastrointestinal tract is mediated by immune mechanisms. Zentralbl Veterinarmed B, 1993 Mar, 40(2), 105 - 12 {Electron microscopic studies of fimbriae and lectin phagocytosis of Salmonella typhimurium variety copenhagen (STMVC)}; Grund S et al.; On Salmonella typhimurium variatio copenhagen (STMVC) strains, isolated from pigeons with acute Salmonellosis, two types of fimbriae can be identified, depending on different growth conditions . In addition to the common 7 nm fimbriae we were able to demonstrate in the electron microscope, thin, curled fimbriae 3 nm in diameter which are characterized by a mannose-resistant hemagglutination . The simultaneous expression of both types of fimbriae on a single bacterial cell can be induced by transferring a microcolony from agar medium (3 nm fimbriae), to the surface of a nutrient broth (7 nm fimbriae) and continuing the incubation . One selected strain expresses only the thin fimbriae on nearly all the bacteria on an agar medium . These thin fimbriae seem to play a role in the lectinophagocytosis in macrophage cultures . The attachment of Salmonellae mediated by these fimbriae as well as the internalization of fimbriated cells by macrophages is shown in the electron microscope and discussed in respect to infection and immunization. Invest Ophthalmol Vis Sci, 1993 Mar, 34(3), 673 - 81 Monoclonal antibody against CD11b/CD18 inhibits endotoxin-induced uveitis; Whitcup SM et al.; PURPOSE . To examine the serial expression of cell adhesion molecules in C3H/HeN mice with endotoxin-induced uveitis, and to study the effect of treatment with a monoclonal antibody against Mac-1 on the development of endotoxin-induced uveitis . METHODS . Immunohistochemical staining was used to document the serial expression of Mac-1, intercellular adhesion molecule-1 (ICAM-1), and lymphocyte function-associated antigen-1 (LFA-1) in eyes of C3H/HeN mice with endotoxin-induced uveitis . Then, in two separate experiments, endotoxin-induced uveitis was produced in a total of 48 mice by injecting Salmonella typhimurium endotoxin into one hind footpad . At the time of endotoxin injection, 24 mice received an intraperitoneal injection of anti-Mac-1 antibody and 24 control mice received an intraperitoneal injection of rat IgG . Histopathologic sections of eyes taken 24 hours after endotoxin injection were graded by two masked observers on a scale of 0 to 4 . RESULTS . Intercellular adhesion molecule-1 was first expressed on the ciliary body epithelium 6 hr after endotoxin injection and Mac-1 and LFA-1 were expressed on infiltrating inflammatory cells 12 hr after endotoxin injection . Treatment with anti-MAC-1 antibody significantly inhibited the development of ocular inflammation when compared with treatment with control IgG (P < 0.001) . CONCLUSION . Intercellular adhesion molecule-1 is expressed in the eye before clinical or histologic signs of inflammation . Furthermore, treatment with antibody against Mac-1 significantly inhibits the development of endotoxin-induced uveitis in mice and suggests that anti-Mac-1 antibody may be useful for treating acute ocular inflammation. Mutagenesis, 1993 Mar, 8(2), 93 - 100 Report of the Association of British Pharmaceutical Industries Collaborative Study Group . Collaborative study to evaluate the inter/intra laboratory reproducibility and phenotypic stability of Salmonella typhimurium TA97a and TA102; Wilcox P et al.; A collaborative trial was carried out to determine the intra/interlaboratory variability of Salmonella typhimurium strains TA102 and TA97a with regard to spontaneous revertant frequency and in response to four model mutagens (cumene hydroperoxide and bleomycin for strain TA102, and 4-nitrophenylenediamine and 4-aminoantipyrine for strain TA97a) . A secondary objective of the trial was to monitor the stability of the strains after storage for up to 8 months and identify any technical problems associated with their use . Thirteen different laboratories participated in the trial, all receiving identical stock cultures of the bacterial strains and samples from the same batch of mutagenic compound . A standard protocol was followed and two independent experiments were carried out within 1 month of receipt of the strains/compounds (phase I), and again after a period of 6-8 months (phase II) . Comparative studies with the standard strain TA100 after treatment with 4-nitrophenylenediamine were carried out as part of phase II . Overall, both strains gave acceptably consistent results in different laboratories and are considered useful for screening purposes when used under standardized conditions . One major source of interlaboratory variability identified for TA102 appears to be the sensitivity of different types of automatic colony counter for detecting the micro-colony revertants that this strain produces. Mutagenesis, 1993 Mar, 8(2), 113 - 20 Mutagenic activation of 4-aminobiphenyl and its N-hydroxy derivatives by microsomes from cultured human uroepithelial cells; Hatcher JF et al.; Activation of the human bladder carcinogen 4-aminobiphenyl (ABP) and its N-hydroxy derivatives was investigated using lysates and subcellular enzyme preparations from cultured human uroepithelial cells (HUC) . Mutagenic activation was determined using Salmonella typhimurium strains TA98; TA98/1,8-DNP6, a derivative deficient in acetyl coenzyme A:N-hydroxyarylamine O-acetyltransferase (OAT); and YG1024, a derivative of TA98 with elevated OAT activity and enhanced sensitivity to mutation by N-hydroxyarylamines . Mutagenicity of ABP catalyzed by HUC microsomes was detected in YG1024 but not in the parent strain TA98 . HUC microsomes also catalyzed the mutagenic activation of N-hydroxy-4-acetylaminobiphenyl (N-OH-AABP) and the relative sensitivity of the tester strains was YG1024 > TA98 > TA98/1,8-DNP6, indicating N-hydroxy-4-aminobiphenyl (N-OH-ABP) as the mutagenic intermediate . In contrast, the mutagenic activity of N-acetoxy-4-acetylaminobiphenyl incubated with HUC microsomes was approximately equal in TA98 and YG1024, and may involve N-acetoxy-4-aminobiphenyl (N-OAc-ABP) as the intermediate . High pressure liquid chromatography (HPLC) of the DNA hydrolysate obtained after incubation of {3H}N-OH-ABP with YG1024, showed N-(deoxyguanosin-8-yl)-4-aminobiphenyl (dG-ABP) as the primary adduct, based on mobility of the radioactivity in comparison with the synthetic standard . Additionally, HUC microsomes catalyzed the binding of {3H}N-OH-ABP to RNA in the presence of 4-acetylaminobiphenyl (AABP), N-OH-AABP and acetyl coenzyme A as acetyl donors, and this binding was blocked by paraoxon . The hydrolysate obtained from incubation of DNA with {3H}N-OH-ABP and HUC microsomes, with AABP as acetyl donor, revealed the formation of dG-ABP adduct.(ABSTRACT TRUNCATED AT 250 WORDS) Mutat Res, 1993 Mar, 293(3), 197 - 204 Acidification of Escherichia coli and Salmonella typhimurium cytoplasm reduces the mutagenic effect of N-methyl-N'-nitro-N-nitrosoguanidine; Oktyabrsky ON et al.; Preliminary acidification of the cytoplasm of E . coli cells growing at pH 6.9 by adding to the medium 50 mM of sodium acetate or propionate reduced the mutagenic effect of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) to almost the spontaneous level . In experiments with S . typhimurium the protective effects of cytoplasm acidification against the mutagenic effect of MNNG was observed at pH 5.5 and was absent at a medium pH of 6.9 . Alkalinization of the cytoplasm by adding 80 mM of methylamine to the growth medium at pH 8.1 did not modify the effect of MNNG on the cells of E . coli and S . typhimurium . Alkalinization of the cytoplasm of E . coli B/r and K12 was followed by a reduction of the intracellular non-protein SH group level by 25 and 50%, respectively . It is supposed that the protective effect of acidification may be due to a decline in the productivity of mutagenically more active intermediates of MNNG when the pH is reduced and the associated fall of the level of intracellular non-protein thiols occurs . The above situation may serve as a model for studying the effects of MNNG and other alkylating agents on cells differing in physiological status. Mutat Res, 1993 Mar, 299(1), 63 - 73 Mutagenicity of nitro- and amino-substituted carbazoles in Salmonella typhimurium . I . Monosubstituted derivatives of 9H-carbazole; Andre V et al.; Mononitro, monoamino and monoacetamido carbazoles were assayed for mutagenicity in Salmonella typhimurium strains TA1535, TA1538, TA1537, TA1977, TA98 and TA100, with and without the addition of S9 from phenobarbital-induced rat liver . The role of bacterial metabolism of the nitro group was also studied using the additional strains TA98NR and TA98/1,8DNP6 . None of the compounds was active in TA1535, while only 2-nitrocarbazole and 3-nitrocarbazole presented a weak mutagenicity towards its pKM101 derivative, TA100 . All four nitrocarbazole isomers were mutagenic for TA1538 and TA98, their activities decreasing in the order: 2-nitrocarbazole approximately 3-nitrocarbazole > 1-nitrocarbazole > 4-nitrocarbazole . Direct-acting mutagenicities for TA1537 were lower than for TA1538, but varied in the same order . Nitro reduction was an important step of metabolic activation of nitrocarbazoles, as indicated by the dramatic reduction of activity with TA98NR, as compared to TA98 . Results obtained with TA98/1,8DNP6 showed that O-acetyltransferase was only partly required for the expression of mutagenic potency of these compounds . 2-Aminocarbazole was a weak direct-acting mutagen for TA1538 and TA98 . Its activity was strongly increased in the presence of S9 mix, while 3-aminocarbazole became active in these conditions . The acetamido derivatives were consistently less mutagenic than their parent amines . These results show that nitrocarbazoles and aminocarbazoles behave as reactive frameshift mutagens, acting mainly through the formation of esterified hydroxylamines . The very low activity of 4-nitrocarbazole might be related to an orientation of the nitro group perpendicular to the aromatic ring. Mutat Res, 1993 Mar, 299(1), 45 - 53 Detection of mutagenic activity in textiles with Salmonella typhimurium; Knasmuller S et al.; A hundred and ninety-six textile samples were tested in a modified version of the Salmonella/microsome assay for release of mutagenic contaminants . As heat sterilization of the samples can result in reduction of mutagenic activity, tests were performed with streptomycin resistant derivatives of Salmonella tester strains TA98 and TA100 . Textile samples were preincubated in buffered saline (PBS), DMSO or ethanol . Subsequently, the fabrics were placed on streptomycin supplemented selective agar plates . In total, 18 samples (9.2%) exerted mutagenic activity . DMSO was the most effective solvent (15 positives) followed by ethanol (9 positive samples) and PBS (7 positives) . Most fabrics (16) caused mutagenic effects only upon metabolic activation with liver S9 mix . Chemical analysis indicates that the positive results obtained with PBS are not due to release of histidine or formaldehyde . Three directly active samples gave negative results in strain TA98NR which is devoid of classical nitroreductase . With one exception all other textiles were negative in strain TA98/1,8-DNP6 (which lacks O-acetyltransferase) . These findings indicate that nitroaromatics and amines might be responsible for the mutagenic effects of the textiles. J Toxicol Sci, 1993 Feb, 18 Suppl 1, 177 - 81 {Reverse mutation test of trandolapril (RU44570) with bacteria}; Aruga F et al.; Mutagenicity of trandolapril (RU44570) was evaluated by the reverse mutation test with bacteria (test strains used: Salmonella typhimurium TA100, TA98, TA1535, TA1537 and Escherichia coli WP2uvrA) . The test was conducted by the preincubation method without metabolic activation (in the absence of S9 mix) and with metabolic activation (in the presence of S9 mix) . The number of revertant colonies in the bacterial strains did not exceed twice that obtained in the solvent control either in the presence or absence of S9 mix . There was no dose-dependent increase in the number of revertant colonies observed . Based on the above results, it is concluded that RU44570 has no mutagenicity (gene mutation) under the conditions of the present study. Microb Pathog, 1993 Feb, 14(2), 95 - 102 Immunization of mice with Salmonella typhimurium C5 aroA expressing a genetically toxoided derivative of the pneumococcal toxin pneumolysin; Paton JC et al.; An attenuated Salmonella strain expressing a genetically toxoided derivative of the pneumococcal toxin pneumolysin was constructed by first transforming a methylation-positive, restriction-negative Salmonella with plasmid pJCP20M, a derivative of pBR322 containing the modified pneumolysin gene . Plasmid DNA was then extracted and transformed into Salmonella typhimurium C5 aroA . The transformant (denoted JM8) was capable of constitutively expressing the modified pneumolysin gene in vitro and stably maintained the recombinant plasmid containing the pneumococcal DNA, even in the absence of antibiotic selection . When JM8, or the parental Salmonella C5 aroA carrying pBR322 (denoted JM6), were administered orally to mice, both strains were capable of at least transient colonization of the Peyer's patches . Sera from JM8 mice (but not those fed JM6) had significant anti-pneumolysin IgG and IgA ELISA titres . Intraperitoneal administration of JM8 resulted in higher anti-pneumolysin IgG titres, but lower specific IgA levels. Enferm Infecc Microbiol Clin, 1993 Feb, 11(2), 93 - 6 {Salmonella typhimurium as the causal agent of pulmonary cavitations}; Saballs P et al.; BACKGROUND: Relation between patients with immunosuppression (malignancy, renal transplant) and bacteremia by Salmonella non-typhi, specially by Salmonella typhimurium, is known . This relation has been published for patients who suffer from AIDS, and so Salmonella bacteremia could even begin the clinical disease . But even though the relation between the infection by Salmonella and AIDS is well known, and the pulmonary involvement in them has been told, this etiology as a producing agent of lung cavitation has not much documentation . METHODS: We examined three patients (two women and one man) suffering from fever of one week of duration, cough, expectoration and thoracic pain in two of them . The third patient had fever and cachexia without clinical symptoms . The man and the two women had a blood count with neutrophilia and leucocytosis in two cases and leucopenia in the other one . All of them suffered a very important depression of cell immunity (CD4 of 140, 70 and 4, respectively) and positive blood cultures for Salmonella typhimurium . RESULTS: Chest X-Ray showed, in all the cases, pulmonary cavities . CONCLUSIONS: Salmonella typhimurium must be included among the agents that can produce pulmonary cavities like Staphylococcus aureus, mycobacteria, fungus and other gram-negative bacilli. Zentralbl Hyg Umweltmed, 1993 Feb, 193(5), 471 - 80 The influence of culture conditions on the susceptibility of Salmonella typhimurium in the Salmonella mutagenicity test; Mersch-Sundermann V et al.; To determine the variability of tester strain susceptibility in the Salmonella mutagenicity assay and to optimize the culturing procedure we examined the influences of the overnight culture period (12-16 h), the use of an additional short-term culturing procedure (1-4 h) and the Salmonella density (cfu/plate) on the rate of revertants per plate . As tester strains we used Salmonella typhimurium TA97, TA98, TA100 and TA102 . As shown previously for other microbial genotoxicity short-term tests (i.e . with Escherichia coli PQ37), we observed the highest susceptibility of the Salmonella strains, i.e . the highest amounts of revertants per plate, when using a 12 h overnight culture followed by a 2 h short-term culturing procedure . We calibrated the bacterial count to 100 x 10(6) cfu per assay by photometric measurement (600 nm) . Initially, we used 0-1 nmole 2,4,7-trinitro-9-fluorenone with S . typhimurium TA97, 0-15 nmole daunomycin with strain TA98, 0-25 nmole sodium azide with strain TA100 and 0-15 nmole methylmethanesulfonate with strain TA102 as reference compounds in the standard plate incorporation test . Subsequently, to evaluate the results of the culturing procedure variations we examined 22 well-known mutagenic and direct-acting (-S9-mix) compounds out of different chemical classes using both the standard and a modified culturing procedure . The comparison of these results showed a 64% (for 4-nitroquinoline-N-oxide) to 421% (for sodium azide) increased amount of revertants for the modified test protocol. Ultramicroscopy, 1993 Feb, 49(1-4), 417 - 25 Size of the export channel in the flagellar filament of Salmonella typhimurium; Ruiz T et al.; The size of the putative export channel in the bacterial flagellar filament appears small (25 A) in studies done by electron microscopy but large (60 A) in studies done by X-ray diffraction . We have undertaken additional studies by electron microscopy to examine some of the possible causes of the difference . A comparison of three-dimensional image reconstructions of native and reconstituted filaments rules out the presence or absence of flagellin monomers in the export channel as the source of the variation in apparent channel size . The channel seen in reconstructions from both kinds of filaments is 25 A in diameter . The difference in the previous studies is more probably a result of artifacts introduced in either the X-ray or the electron microscopical methodology . Comparisons of three-dimensional reconstructions from images of filaments embedded in various stains (anionic, cationic and neutral) and in ice, taken at a range of defocuses, rule out the two most likely sources of artifact in electron microscopy (i.e., staining artifacts and defocus phase contrast) . Based on these studies we suggest that the channel seen in the image reconstructions is free of exported flagellin monomers, that its true diameter is about 25 A, and, therefore, that the flagellin monomer must be unfolded to pass along it. Mol Gen Genet, 1993 Feb, 237(1-2), 273 - 86 Integration host factor (IHF) modulates the expression of the pyrimidine-specific promoter of the carAB operons of Escherichia coli K12 and Salmonella typhimurium LT2; Charlier D et al.; We report the identification of Integration Host Factor (IHF) as a new element involved in modulation of P1, the upstream pyrimidine-specific promoter of the Escherichia coli K12 and Salmonella typhimurium carAB operons . Band-shift assays, performed with S-30 extracts of the wild type and a himA, hip double mutant or with purified IHF demonstrate that, in vitro, this factor binds to a region 300 bp upstream of the transcription initiation site of P1 in both organisms . This was confirmed by deletion analysis of the target site . DNase I, hydroxyl radical and dimethylsulphate footprinting experiments allowed us to allocate the IHF binding site to a 38 bp, highly A+T-rich stretch, centred around nucleotide -305 upstream of the transcription initiation site . Protein-DNA contacts are apparently spread over a large number of bases and are mainly located in the minor groove of the helix . Measurements of carbamoyl-phosphate synthetase (CPSase) and beta-galactosidase specific activities from car-lacZ fusion constructs of wild type or IHF target site mutants introduced into several genetic backgrounds affected in the himA gene or in the pyrimidine-mediated control of P1 (carP6 or pyrH+/-), or in both, indicate that, in vivo, IHF influences P1 activity as well as its control by pyrimidines . IHF stimulates P1 promoter activity in minimal medium, but increases the repressibility of this promoter by pyrimidines . These antagonistic effects result in a two- to threefold reduction in the repressibility of promoter P1 by pyrimidines in the absence of IHF binding . IHF thus appears to be required for maximal expression as well as for establishment of full repression . IHF could exert this function by modulating the binding of a pyrimidine-specific regulatory molecule. J Appl Bacteriol, 1993 Feb, 74(2), 181 - 90 An ion-exchange based extraction method for the detection of salmonellas in soil; Turpin PE et al.; A method that uses a cation-exchange resin (Chelex 100) and differential centrifugation for the extraction and detection of salmonellas in soil was developed . The extraction efficiencies of a range of materials were examined and Chelex plus polyethylene glycol was identified as the best combination . Shake speeds, shake times and differential centrifugation speeds were selected to give an optimum salmonella recovery . The Chelex method accurately enumerated 1 cell per 10 g of nonsterile soil within 24 h . Addition of glycerol to soil samples enabled storage at -70 degrees C for 85 d without significant decreases in salmonella numbers . The Oxoid Salmonella Rapid Test (SRT) could be used to pre-screen large numbers of soil samples for the presence of salmonellas, prior to analysis by the Chelex method . The SRT method detected Salmonella typhimurium at levels as low as 2.5 cells per 10 g of nonsterile soil. Poult Sci, 1993 Feb, 72(2), 259 - 66 Influence of a novel oxy-halogen compound on early growth and nitrogen retention of broiler chickens challenged with Salmonella; Pardue SL et al.; The potential of a novel oxy-halogen compound (OHC) to alter early growth and nitrogen retention of broiler chickens challenged with Salmonella was evaluated . Three hundred and twenty female broiler chicks (Arbor Acres x Arbor Acres) were weighed and distributed randomly within a 2 x 4 factorial arrangement of treatments . Main effects examined were the presence or absence of Salmonella typhimurium (ST) inoculation and OHC treatment . At hatching, 80 chicks were placed in electrically heated brooder batteries in each of four identical isolation rooms . Chicks designated to receive 100 microL of an oral inoculum containing 10(5) ST cfu at 3 days of age were in two of the rooms, and uninoculated chicks were raised in the other two rooms . Four replicates of 10 chicks each received drinking water containing either 0, .05, .1, or .5% OHC for each level of ST . Chicks administered .05% OHC exhibited enhanced (P < or = .01) growth at 7 and 14 days of age when compared with control values . A significant OHC by ST interaction was observed at 7 (P < or = .0001) and 14 (P < or = .03) days of age . Feed utilization was improved (P < or = .01) by OHC administration (.05 and .1%) from hatching to 7 days of age . The administration of OHC reduced (P < or = .01) nitrogen excretion and enhanced (P < or = .01) nitrogen retention by chicks at Day 7 . Cecal ST log10 counts at 7 days of age for chicks given water containing 0, .05, or .1% OHC were 4.72, 3.93, and 3.74, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) J Bacteriol, 1993 Feb, 175(4), 1032 - 7 Molecular cloning, sequencing, and mapping of the gene encoding protease I and characterization of proteinase and proteinase-defective Escherichia coli mutants; Ichihara S et al.; Clones carrying the gene encoding a proteinase were isolated from Clarke and Carbon's collection, using a chromogenic substrate, N-benzyloxycarbonyl-L-phenylalanine beta-naphthyl ester . The three clones isolated, pLC6-33, pLC13-1, and pLC36-46, shared the same chromosomal DNA region . A 0.9-kb Sau3AI fragment within this region was found to be responsible for the overproduction of the proteinase, and the nucleotide sequence of the region was then determined . The proteinase was purified to homogeneity from the soluble fraction of an overproducing strain possessing the cloned gene . N-terminal amino acid sequencing of the purified protein revealed that the cloned gene is the structural gene for the protein, with the protein being synthesized in precursor form with a signal peptide . On the basis of its molecular mass (20 kDa), periplasmic localization, and substrate specificity, we conclude this protein to be protease I . By using the gene cloned on a plasmid, a deletion mutant was constructed in which the gene was replaced by the kanamycin resistance gene (Kmr) on the chromosome . The Kmr gene was mapped at 11.8 min, the gene order being dnaZ-adk-ush-Kmr-purE, which is consistent with the map position of apeA, the gene encoding protease I in Salmonella typhimurium . Therefore, the gene was named apeA . Deletion of the apeA gene, either with or without deletion of other proteinases (protease IV and aminopeptidase N), did not have any effect on cell growth in the various media tested. Proc Natl Acad Sci U S A, 1993 Feb 1, 90(3), 1033 - 7 Molecular, functional, and evolutionary analysis of sequences specific to Salmonella; Groisman EA et al.; In that salmonellae have been implicated in an unprecedented array of diseases, sequences found to be specific to this species are often thought to be involved in the virulence attributes not seen in other enteric bacteria . To identify the molecular, genetic, and phenotypic characteristics that differentiate bacterial species, we analyzed five cloned DNA fragments that were originally described as being confined to Salmonella . Most of these segments mapped to unique positions on the Salmonella typhimurium chromosome indicative of independent evolutionary events, and three had G+C contents considerably lower than that of the Salmonella genome, suggesting that they arose through horizontal transfer . The nucleotide sequence was determined for one of the clones exhibiting an atypical base composition . This 4.9-kb fragment contained an open reading frame with structural similarity to the LysR family of transcriptional regulators . Strains harboring deletions in this region were tested for > 120 phenotypic characteristics including the effects on a collection of environmentally regulated lac gene fusions . In addition, all deletion strains behaved like the wild-type parent when tested for virulence in mice. Pediatr Infect Dis J, 1993 Feb, 12(2), 139 - 45 Multiply resistant nontyphoidal Salmonella gastroenteritis in children; Maiorini E et al.; From January, 1990, to December 31, 1990, 75 children with multiply resistant Salmonella gastroenteritis were studied at the Children's Hospital "Ricardo Gutierrez" of Buenos Aires . These children ranged from 1 month to 15 years of age . Infection was community-acquired in 20 (26.6%), nosocomially acquired in 50 (66.7%) and undetermined in 5 . Thirty-nine (52%) had grossly bloody stools . Fever occurred at some point in the clinical course in 61 children (81.3%) with a duration of 1 to 33 days (mean, 6.7 days) . The duration of diarrhea (1 to 69 days) was longer in those who developed complications (P < 0.001) . Six (8%) developed enterocolitis (2 with bowel perforation), 1 had a pulmonary abscess and 8 (11.4%) had bacteremia; 4 children died (5.3%) . Salmonella typhimurium was the most common serovar (85.3%) . Ninety percent minimum inhibitory concentration studies demonstrated that all strains were resistant to ampicillin (> 128 micrograms/ml), cephalothin (> 128 micrograms/ml), cefuroxime (> 128 micrograms/ml), nalidixic acid (> 256 micrograms/ml), rifampin (> 256 micrograms/ml), gentamicin (> 256 micrograms/ml) and tobramycin (256 micrograms/ml); 77.3% of strains were resistant to ceftazidime (32 micrograms/ml), 97.6% to netilmicin (> 256 micrograms/ml), 92.8% to amikacin (256 micrograms/ml), 24.4% to isepamicin (32 micrograms/ml), 5.3% to chloramphenicol (4 micrograms/ml) and 2.7% to cefoxitin (2 micrograms/ml) . The 90% minimum inhibitory concentration of cefotaxime and ceftazidime was reduced by the addition of clavulanate . Aggressive multiply resistant Salmonella strains are a major pediatric problem in Buenos Aires. J Bacteriol, 1993 Feb, 175(3), 802 - 10 Salmonella typhimurium fliG and fliN mutations causing defects in assembly, rotation, and switching of the flagellar motor; Irikura VM et al.; FliG, FliM, and FliN are three proteins of Salmonella typhimurium that affect the rotation and switching of direction of the flagellar motor . An analysis of mutant alleles of FliM has been described recently (H . Sockett, S . Yamaguchi, M . Kihara, V . M . Irikura, and R . M . Macnab, J . Bacteriol . 174:793-806, 1992) . We have now analyzed a large number of mutations in the fliG and fliN genes that are responsible for four different types of defects: failure to assembly flagella (nonflagellate phenotype), failure to rotate flagella (paralyzed phenotype), and failure to display normal chemotaxis as a result of an abnormally high bias to clockwise (CW) or counterclockwise (CCW) rotation (CW-bias and CCW-bias phenotypes, respectively) . The null phenotype for fliG, caused by nonsense or frameshift mutations, was nonflagellate . However, a considerable part of the FliG amino acid sequence was not needed for flagellation, with several substantial in-frame deletions preventing motor rotation but not flagellar assembly . Missense mutations in fliG causing paralysis or abnormal switching occurred at a number of positions, almost all within the middle one-third of the gene . CW-bias and CCW-bias mutations tended to segregate into separate subclusters . The null phenotype of fliN is uncertain, since frameshift and nonsense mutations gave in some cases the nonflagellate phenotype and in other cases the paralyzed phenotype; in none of these cases was the phenotype a consequence of polar effects on downstream flagellar genes . Few positions in FliN were found to affect switching: only one gave rise to the CW mutant bias and only four gave rise to the CCW mutant bias . The different properties of the FliM, FliG, and FliN proteins with respect to the processes of assembly, rotation, and switching are discussed. Infect Immun, 1993 Feb, 61(2), 719 - 28 Antibacterial activity of lactoferrin and a pepsin-derived lactoferrin peptide fragment; Yamauchi K et al.; Although the antimicrobial activity of lactoferrin has been well described, its mechanism of action has been poorly characterized . Recent work has indicated that in addition to binding iron, human lactoferrin damages the outer membrane of gram-negative bacteria . In this study, we determined whether bovine lactoferrin and a pepsin-derived bovine lactoferrin peptide (lactoferricin) fragment have similar activities . We found that both 20 microM bovine lactoferrin and 20 microM lactoferricin release intrinsically labeled {3H}lipopolysaccharide ({3H}LPS) from three bacterial strains, Escherichia coli CL99 1-2, Salmonella typhimurium SL696, and Salmonella montevideo SL5222 . Under most conditions, more LPS is released by the peptide fragment than by whole bovine lactoferrin . In the presence of either lactoferrin or lactoferricin there is increased killing of E . coli CL99 1-2 by lysozyme . Like human lactoferrin, bovine lactoferrin and lactoferricin have the ability to bind to free intrinsically labeled {3H}LPS molecules . In addition to these effects, whereas bovine lactoferrin was at most bacteriostatic, lactoferricin demonstrated consistent bactericidal activity against gram-negative bacteria . This bactericidal effect is modulated by the cations Ca2+, Mg2+, and Fe3+ but is independent of the osmolarity of the medium . Transmission electron microscopy of bacterial cells exposed to lactoferricin show the immediate development of electron-dense "membrane blisters." These experiments offer evidence that bovine lactoferrin and lactoferricin damage the outer membrane of gram-negative bacteria . Moreover, the peptide fragment lactoferricin has direct bactericidal activity . As lactoferrin is exposed to proteolytic factors in vivo which could cleave the lactoferricin fragment, the effects of this peptide are of both mechanistic and physiologic relevance. Infect Immun, 1993 Feb, 61(2), 640 - 9 Light emission from a Mudlux transcriptional fusion in Salmonella typhimurium is stimulated by hydrogen peroxide and by interaction with the mouse macrophage cell line J774.2; Francis KP et al.; Hydrogen peroxide is known to induce a multigenic response in Salmonella typhimurium cells . We have used a Mudlux transcriptional reporter system to identify and isolate fusions in the virulent strain SL1344 which respond to hydrogen peroxide in vitro by light production, and one of these fusions, MPG203, has been further characterized . Transient light production was observed from MPG203 at levels of hydrogen peroxide as low as 10 microM . However, high levels of this toxic oxidizing agent resulted in light suppression, particularly at low bacterial densities . This fusion was also shown to produce light following adhesion to cells of the mouse macrophage cell line J774.2 . Furthermore, the response was greatly reduced in the presence of catalase, directly implicating hydrogen peroxide as the eliciting agent and suggesting the involvement of the hydrogen peroxide-induced bacterial stress response in the infection process . Chemiluminescence studies also indicated that inhibition of the respiratory burst may occur as the infection ratio is increased . In addition, the level of light produced from bacteria within individual macrophage cells was shown to vary. Infect Immun, 1993 Feb, 61(2), 504 - 11 The Salmonella typhimurium virulence plasmid increases the growth rate of salmonellae in mice; Gulig PA et al.; The virulence plasmids of Salmonella typhimurium and other invasive Salmonella serovars have long been associated with the ability of these bacteria to cause systemic infection beyond the intestines in orally inoculated animals . Genetic analysis of virulence genes on the high-molecular-weight plasmids has revealed that no more than five genes spanning a 6.2-kb region are sufficient to replace the entire plasmid for conferring virulence . However, the exact virulence function(s) encoded by these genes has not been elucidated . In this report, we measured the possible effect of the virulence plasmid on the growth rate of S . typhimurium in mice by two complementary procedures . The first procedure used segregation of a temperature-sensitive plasmid in vivo to provide a measure of bacterial divisions and the number of recovered marker plasmid-containing salmonellae as a measure of killing . In the second procedure, aroA deletions were transduced into virulence plasmid-containing and plasmid-cured S . typhimurium . Since AroA- salmonellae are inhibited for growth in vivo, if the virulence plasmid affected only growth rate, no difference in the recoveries of the paired AroA- strains would be seen . Virulence plasmid-containing S . typhimurium segregated the marker plasmid more rapidly than did the virulence plasmid-cured strain, and AroA- derivatives of both strains were recovered equally from mice . Therefore, the S . typhimurium virulence plasmid increased growth rate but had no detectable effect on killing or bacterial movement into deep tissues . To examine whether the plasmid accomplished this function by affecting the intracellular/extracellular location of bacteria, orally infected mice were injected with gentamicin to kill the extracellular bacteria . Wild-type and plasmid-cured S . typhimurium strains were equally resistant to gentamicin in vivo and hence most likely located intracellularly to equal degrees . When wild-type and plasmid-cured S . typhimurium strains were sequestered within peritoneal chambers in mice, the resulting extracellular growth was equal . Therefore, the virulence plasmid increases the growth rate of S . typhimurium in mice, probably within mouse cells. J Antimicrob Chemother, 1993 Feb, 31(2), 313 - 9 Comparative efficacies of azithromycin and ciprofloxacin against experimental Salmonella typhimurium infection in mice; Butler T et al.; Azithromycin was compared with ciprofloxacin for the treatment of established intracellular infection with Salmonella typhimurium LT-2 in CF-1 mice . For studies of mortality, mice received five times the LD50 of organisms intraperitoneally and were given drugs intragastrically once daily for seven days . For studies of in-vivo antibacterial activity, splenic viable counts were measured in mice that had received 0.5 times the intraperitoneal LD50 and had been given drugs for three days . The MICs of azithromycin and ciprofloxacin, respectively, against LT-2 were 4.0 and 0.03 mg/L . The 50% protective doses of the drugs required to prevent mortality were azithromycin 24.7 mg/kg/day, and ciprofloxacin 30.2 mg/kg/day . Treatment with azithromycin and ciprofloxacin in doses of 25 and 100 mg/kg/day resulted in reduction of mean log10 cfu per spleen . Splenic concentrations of azithromycin up to 8 h after treatment exceeded its MIC against the LT-2 strain, whereas serum levels were less than the MIC . These results indicated that azithromycin given orally once daily was as effective as ciprofloxacin against established murine Salmonella infection and that the efficacy of azithromycin correlated with adequate tissue concentrations of antibiotic. Mol Microbiol, 1993 Feb, 7(3), 351 - 8 Isolation and characterization of a topA mutant of Shigella flexneri; Bhriain NN et al.; Shigella flexneri was shown to possess a homologue of the Escherichia coli K-12 topA gene which encodes DNA topoisomerase I . The S . flexneri topA gene was replaced by a copy of the E . coli K-12 topA gene which has been insertionally inactivated by transposon Tn10 . The topoisomer distribution of reporter plasmids showed that the presence of this topA lesion in S . flexneri correlated with an increase in the level of negative DNA supercoiling in the mutant, indicating that topoisomerase I is required to relax DNA in S . flexneri as it is in E . coli and Salmonella typhimurium . The introduction of the topA mutation also resulted in repression of transcription of a thermally regulated invasion gene located on the 230 kb virulence plasmid . In addition, the topA mutant was hypersensitive to growth medium osmolarity, was unable to grow on MacConkey indicator plates and exhibited an increased doubling time under all growth conditions tested . All of these phenotypes were fully complemented in trans by a cloned copy of the E . coli topA gene carried on a recombinant plasmid . Unlike E . coli topA mutants which acquire compensatory mutations at a high frequency, such compensatory mutations were not detected in the S . flexneri topA::Tn10 mutant. Antimicrob Agents Chemother, 1993 Feb, 37(2), 240 - 5 Relationship between antibacterial activity and porin binding of lactoferrin in Escherichia coli and Salmonella typhimurium; Naidu SS et al.; The effect of lactoferrin (Lf) on bacterial growth was tested by measuring conductance changes in the cultivation media by using a Malthus-AT system and was compared with the magnitude of 125I-labeled Lf binding in 15 clinical isolates of Escherichia coli . The binding property was inversely related to the change in bacterial metabolic rate (r = 0.91) and was directly related to the degree of bacteriostasis (r = 0.79) . The magnitude of Lf-bacterium interaction showed no correlation with the MIC of Lf . In certain strains, Lf at supraoptimal levels reduced the bacteriostatic effect . Thus, the Lf concentration in the growth media was critical for the antibacterial effect . The cell envelopes of Salmonella typhimurium 395MS with smooth lipopolysaccharide (LPS) and its five isogenic rough mutants revealed 38-kDa porin proteins as peroxidase-labeled-Lf-reactive components in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot (ligand blot) analysis . However, in the whole cell binding assay, parent strain 395MS demonstrated a very low interaction with 125I-Lf . On the other hand, Lf interaction gradually increased in correspondence with the decrease in LPS polysaccharide moiety in the isogenic rough mutants . Conductance measurement studies revealed that the low-level-Lf-binding (low-Lf-binding) strain 395MS with smooth LPS was relatively insusceptible to Lf, while the high-Lf-binding mutant Rd was more susceptible to Lf . These data suggested a correlation between Lf binding to porins and the Lf-mediated antimicrobial effect . The polysaccharide moiety of LPS shielded porins from the Lf interaction and concomitantly decreased the antibacterial effect. Biol Pharm Bull, 1993 Feb, 16(2), 201 - 2 Low mitogenic activity of synthetic lipid A analog, 2,3-acyloxyacylgalactosamine-4-phosphate, in cultured murine splenocytes; Shimizu T et al.; The mitogenicity of chemically synthesized lipid A analogs, 2,3-acyloxyacylglucosamine-4-phosphate (A-103) and 2,3-acyloxyacylgalactosamine-4-phosphate (A-113), was compared . Synthetic lipid A analogs of the disaccharide-type (506), the monosaccharide-type (A-103) suspended in RPMI-1640 medium supplemented with triethylamine, and Salmonella typhimurium LT-2 lipopolysaccharide (LPS) were capable of increasing the incorporation of {3H}thymidine into splenocytes of C57BL/6 mice at various doses ranging from 1.0 to 100 micrograms/ml . However, the mitogenic activity of A-113 at these doses was markedly weaker than the activity of the above materials . When the A-103 and A-113 were suspended in RPMI-1640 medium supplemented with ethanol, the mitogenic activity of A-113 also showed lower activity than that of A-103 in the splenocytes of C57BL/6 mice . These findings indicate that the mitogenic activity of synthetic lipid A of the monosaccharide-type is affected by a kind of composed sugar. J Gen Microbiol, 1993 Feb, 139 ( Pt 2), 259 - 66 Characterization of the hemA-prs region of the Escherichia coli and Salmonella typhimurium chromosomes: identification of two open reading frames and implications for prs expression; Post DA et al.; The prs gene, encoding phosphoribosylpyrophosphate synthetase, is preceded by a leader, which is 302 bp long in Escherichia coli and 417 bp in Salmonella typhimurium . A potential open reading frame (ORF) extends across the prs promoter and into the leader . The region between the prs coding region and an upstream gene (hemA) in E . coli and S . typhimurium was cloned, sequenced and shown to encode two ORFs of unknown function . ORF 1 encodes a 23 kDa protein and ORF 2 a 31 kDa protein, as observed by denaturing PAGE of extracts of cells bearing plasmids encoding the ORFs . Both ORFs are transcribed in the same direction as the prs gene with ORF 2 extending into the prs leader . Northern blot analysis showed that the prs message in E . coli was on 1.3 and 2.7 kb transcripts . The shorter transcript encoded the prs gene only, while the longer transcript also encoded the two ORFs . Thus, the prs gene is transcribed from two promoters, the first promoter (P1) originating upstream of ORF 1, and expressing the prs gene in a tricistronic operon and a second promoter (P2), located within the ORF 2 coding frame, which transcribes the prs gene only . The transcripts encoding prs only were 20 times as abundant as the tricistronic transcripts under all conditions examined . This was the case whether cells containing plasmid-encoded or only chromosomally encoded copies of the hemA-prs region were probed for these transcripts . Derepression of the prs gene upon pyrimidine starvation was shown to be due to an increase in the amount of message originating from the promoter P2. Mutat Res, 1993 Feb, 301(2), 113 - 9 Activation of benzo{a}pyrene and 2-aminoanthracene to bacteria mutagens by mussel digestive gland postmitochondrial fraction; Michel XR et al.; The ability of the mussel postmitochondrial fraction (S9) to activate benzo{a}pyrene (BaP) and 2-aminoanthracene (2AA) to mutagenic metabolites towards Salmonella typhimurium strain TA98 was tested . The mechanisms involved in this activation were investigated and mussel cytochrome P-450-dependent monooxygenases and its NADPH cytochrome c reductase were found to contribute to the activation of BaP . This activation was improved by treating the mussel with 4,5,4',5'-tetrachlorobiphenyl (TCB) (a 3-methylcholanthrene-type inducer of cytochrome P-450-dependent monooxygenase in marine fish) and was inhibited by alpha-naphthoflavone (ANF), a cytochrome P-450 inhibitor . However, both BaP activation and cytochrome P-450-related metabolic activities are much weaker in mussels than in vertebrates . Mussel S9 activates aromatic amines more effectively than BaP . Pretreatment of mussels with TCB or addition of ANF in the incubation medium has no effect on 2AA activation . As suggested by Kurelec (1985), aromatic amine metabolism may be supported by a flavoprotein mixed-function amine oxidase which is NADPH-dependent. Mutat Res, 1993 Feb, 298(4), 269 - 75 Mutagenic activity of some platinum and palladium complexes; Uno Y et al.; The mutagenic properties of 16 platinum compounds were studied using Salmonella typhimurium TA98 and TA100 . Eight of the compounds were considered direct mutagens, as their mutagenicity was not dependent on metabolic activation by liver extracts . Potent mutagenicity and high toxicity were exhibited by cis-Pt(NH3)2Br2, cis-Pt(NH3)2Cl2, Pt(C5H12N2)Cl2 and Pt(en)Cl2 for both bacterial strains . When distilled water was used as the carrier solvent, these compounds were strongly mutagenic and toxic, but much less so when dimethyl sulfoxide was the solvent. Mutat Res, 1993 Feb, 298(4), 261 - 7 Comparative study on the mutagenicity of three structurally related substituted aniline mustards in the Salmonella/microsome assay; Voutsinas G et al.; The ortho, meta and para isomers of N,N-bis(2-chloroethyl)aminocinnamic acid were tested for their ability to mutate Salmonella typhimurium strains in the Salmonella/microsome mutagenicity test . The aim of the work was to establish a structure-activity relationship between these three isomers . The drugs were found to induce base-pair substitutions, causing dose-dependent increases in his+ revertants, in strains TA100 and TA1535 . The study showed that the position of the substituent groups influenced the mutagenic activity of the compounds . The ortho isomer exhibited a poorer mutagenic effect than meta and this was found to be a weaker mutagen than para . The presence of metabolic activation enzymes in the test system induced a further increase in his+ revertants, in strains TA100 and TA1535, which is consistent with the findings for melphalan, a cancer chemotherapeutic agent with a chemical structure similar to that of the isomers tested. Science, 1993 Jan 29, 259(5095), 686 - 8 Selection of bacterial virulence genes that are specifically induced in host tissues; Mahan MJ et al.; A genetic system was devised that positively selects for bacterial genes that are specifically induced when bacteria infect their host . With the pathogen Salmonella typhimurium, the genes identified by this selection show a marked induction in bacteria recovered from mouse spleen . Mutations in all ivi (in vivo-induced) genes that were tested conferred a defect in virulence . This genetic system was designed to be of general use in a wide variety of bacterial-host systems and has several applications in both vaccine and antimicrobial drug development. Biochemistry, 1993 Jan 26, 32(3), 806 - 11 Inhibition of tryptophan synthase by (1-fluorovinyl)glycine; Xu Y et al.; Tryptophan synthase (alpha 2 beta 2 complex) from Salmonella typhimurium catalyzes the formation of tryptophan from serine and indole . The enzyme is inactivated by (1-fluorovinyl)glycine . Concomitant with enzyme inactivation, the absorbance at 485 nm increases, indicating covalent modification of pyridoxal 5'-phosphate . It is proposed that inactivation involves elimination of HF to form an allene, which reacts with a nucleophile at the active site . The inactivation reaction involves an alpha,beta-elimination, as does the formation of tryptophan from indole and serine . The inactivation occurs with k(in) > 1.3 s-1, which is very close to k(cat) (6.4 s-1) for the formation of tryptophan from indole and serine . The inactive enzyme (alpha 2 beta 2) regains activity with k(off) = 0.005 min-1 . Aminoacetone is formed during reaction, and pyridoxal 5'-phosphate is regenerated . Tryptophan synthase also catalyzes the dehydration of serine, or 3-fluoroalanine, to pyruvate in the absence of indole . This reaction involves an alpha,beta-elimination and the intermediate formation of an aminoacrylate adduct with pyridoxal 5'-phosphate, as does the formation of tryptophan . Pyruvate formation proceeds at less than 5% the rate of tryptophan formation . With {2-2H}serine an isotope effect (DVmax = 1.5) is observed . We propose that pyruvate formation is limited by the rate of hydration of the aminoacrylate intermediate and the rate of the abstraction of the serine alpha-hydrogen. Gene, 1993 Jan 15, 123(1), 143 - 4 Complete sequence of the Salmonella typhimurium gene encoding malate dehydrogenase; Lu CD et al.; The nucleotide (nt) sequence of mdh (encoding malate dehydrogenase) in Salmonella typhimurium is presented . The relative positions of argR (encoding arginine repressor) and mdh on the chromosome of S . typhimurium were determined from analysis of the nt sequence . The homology of the 3'-terminal end with only one of two published mdh sequences in Escherichia coli identifies the correct sequence in this organism. Gene, 1993 Jan 15, 123(1), 121 - 5 Characterization of the gene coding for the Rickettsia prowazekii DNA primase analogue; Marks GL et al.; The gene (dnaG) coding for DNA primase in the obligate intracellular parasitic bacterium, Rickettsia prowazekii, has been isolated and characterized . An open reading frame (ORF) of 1848 bp capable of encoding 616 amino acids (aa) is located 18 bp upstream from the gene coding for the major sigma factor of R . prowazekii, sigma 73 . Based on aa sequence comparisons of DNA primase from R . prowazekii, Escherichia coli, Salmonella typhimurium and Bacillus subtilis, we propose that R . prowazekii dnaG begins 69 bp into the ORF and encodes 593 aa with a calculated M(r) of 68,683 . An upstream ORF overlaps 66 of the first 69 bp of the larger R . prowazekii dnaG ORF, suggesting either an overlapping gene structure or the generation of the smaller protein product of 593 aa . Predicted aa sequence of R . prowazekii primase compared to E . coli, S . typhimurium and B . subtilis primases reveals 30.5%, 30.5% and 29.7% aa identity, respectively . The R . prowazekii dnaG gene failed to complement an E . coli dnaG temperature sensitive mutation perhaps due to poor expression of the gene or inability to function properly in E . coli . The gene organization of an ORF followed by DNA primase (dnaG) and then the major sigma factor (rpoD) is consistent with the major macromolecular synthesis operons of E . coli, S . typhimurium and B . subtilis. Cancer Lett, 1993 Jan 15, 68(1), 75 - 82 Modulation of cytochrome P-450IA1-mediated mutagenicity, DNA binding and metabolism of benzo{a}pyrene by Chinese medicinal herbs; Wong BY et al.; Oldenlandia diffusa (OD) and Scutellaria barbata (SB) have been used in traditional Chinese medicine for treating liver, lung and rectal tumors . We previously showed that they inhibited mutagenesis, DNA binding and metabolism of benzo{a}pyrene (BaP) and aflatoxin B1 (AFB1) bioactivated by Aroclor 1254-induced rat hepatic S9 . The purpose of this study was to investigate the effects of OD and SB on the cytochrome P-450IA1-mediated mutagenicity of BaP in Salmonella typhimurium TA100 using beta-naphthoflavone (beta NF)-induced rat hepatic S9 . We also determined the effects of OD and SB on cytochrome P-450IA1-linked ethoxyresorufin O-deethylase (EROD) activity in beta NF-induced hepatic microsomes . In addition, we studied the effects of these two herbs on BaP metabolite binding to calf thymus DNA and using high performance liquid chromatography (HPLC) we investigated the effects of OD and SB on the metabolism of BaP by beta NF-induced S9 . Our experimental results showed that OD and SB inhibited the mutagenicity of BaP in the presence of either non-induced or beta NF-induced S9 . SB significantly inhibited BaP binding to DNA . These effects correlated with the inhibition of cytochrome P-450IA1-linked EROD activity in beta NF-induced microsomes and with an inhibition of beta NF-induced S9 mediated metabolism of {3H}BaP as determined by HPLC . These results suggest that OD and SB may possess antimutagenic activity by inhibiting P-450IA-mediated metabolism of BaP. J Mol Biol, 1993 Jan 5, 229(1), 79 - 84 Domain organization of the subunit of the Salmonella typhimurium flagellar hook; Morgan DG et al.; The deduced amino acid sequences of the family of axial proteins of the bacterial flagellum possess N and C-terminal heptad repeats of hydrophobic amino acid residues, which suggests that these proteins all fold to form bundles of alpha-helices (e.g . coiled coils) . There is evidence that flagellin, which is one of the axial proteins, has an axially oriented bundle of alpha-helices that gives rise to the inner, rod-shaped domains seen in electron density maps . We present evidence that a second member of the family, the hook subunit, also has such an axially oriented, rod-shaped domain . In three-dimensional reconstructions from electron micrographs of the helical hook of Salmonella typhimurium, the rod-shaped domain has a diameter of 18 A, which is that expected for a coiled coil . The corresponding domain in the flagellin subunit of the filament, however, is larger, having a diameter of 24 A suggesting a bundle of three or more alpha-helices . In addition to the rod-shaped domain, the hook has two other domains . At a radius of 55 A is the middle spheroidal domain about 25 A in diameter and at a radius of 75 A is the outer ellipsoidal domain about 20 A by 30 A by 40 A . The flagellin subunit also has a middle and an outer domain although they appear different from those of the hook . This is no doubt a result of the lack of any sequence similarity of the hook and flagellin subunits, apart from the N and C-terminal heptad repeats . Along the hook axis, there is a 25 A wide channel, which presumably serves in the export of hook and flagellin subunits in the assembly of the filament . There is a comparably sized channel in the filaments as deduced from electron micrographs . Thus, electron microscopy consistently finds a small channel, whereas in X-ray diffraction studies of the filament, the channel size appeared to be about 60 A . At a diameter of 60 A, the channel could pass the flagellin or hook subunit in its completely folded state, but if the channel is only 25 A in diameter, the subunit would have to be at least partially unfolded in order to pass through the channel. J Mol Biol, 1993 Jan 5, 229(1), 258 - 62 Crystallization and preliminary X-ray diffraction analysis of ScrY, a specific bacterial outer membrane porin; Forst D et al.; The sucrose-specific outer membrane porin ScrY of Salmonella typhimurium was isolated from Escherichia coli K-12 strain KS 26 containing the plasmid pPSO112 . The protein was purified to homogeneity by differential extraction of the cell envelope in the presence of the detergents sodium dodecyl sulfate and lauryl (dimethyl)-amine oxide (LDAO) . The porin had apparent molecular weights of 58 kDa and 120 kDa for the monomer and for the trimer, respectively, on SDS/PAGE . The purified trimers were crystallized using poly(ethylene glycol) 2000 and the detergents octylglucoside (OG) and hexyl-(dimethyl)-amine oxide (C6DAO) . X-ray diffraction of the crystals showed reflections to 2.3 A . The space group of the crystals was R3 and the lattice constants of the hexagonal axes were a = b = 112.85 A and c = 149.9 A . The crystal volume per unit of protein molecular weight was 3.47 A3/Da. Cell Biol Toxicol, 1993 Jan-Mar, 9(1), 33 - 47 Mutagenicity of structurally related phenylazo-3-pyridines in Salmonella typhimurium; Shahin MM; Studies were conducted to explore structure-activity relationships for 4'-N,N-dimethylamino-1'-phenylazo-3-pyridine and nine structurally related compounds in Salmonella typhimurium tester strains TA1535, TA100, TA1537, TA1538, TA98 . Each compound was tested for mutagenicity at five or more concentrations that varied from 10-5000 micrograms/plate . We used the standard plate test and the investigations were carried out both in the absence and presence of Aroclor-1254-induced rat-liver homogenate and the components of the NADPH-generating system . Negative response was observed for 4'-N,N-dimethylamino-1'-phenylazo-3-pyridine and five of its analogues (4'-N,N-diethylamino-1' phenylazo-3-pyridine; 4'-N,N-di-(beta-hydroxyethylamino)-1' phenylazo-3-pyridine; 4'-N-methylamino sulfonic acid-1'-phenylazo-3-pyridine; 4'-N,N-dimethylamino-6'-acetamido-1' phenylazo-3-pyridine, and 4'-N,N-di-(beta-hydroxyethylamino)-6'-methyl-l' phenylazo-3-pyridine) . When S9 induced by Aroclor-1254 was present, the compound 4'-N,N-dimethylamino-6-methoxy-1' phenylazo-3-pyridine exhibited mutagenic activity in the two strains TA1538 and TA98 . The compound 4',6'-diamino-3-methyl-1'-phenylazo-3-pyridine was also mutagenic, both in the presence and in the absence of S9 mix . The two compounds 4'-N,N-dimethylamino-6-butoxy-1'-phenylazo-3-pyridine and 4'N,N-di-(beta-hydroxyethylamino)-1'-phenylazo-3-{6-N,N-di-(beta- hydroxyethylamino) pyridine were either weakly mutagenic or nonmutagenic . On the basis of these data, it is concluded that the mutagenicity of phenylazo-3-pyridines, like monocyclic aromatic amines and azo dyes, is influenced by the nature of the substituent chemical groups and their positions in the molecular structure of the compounds. Environ Mol Mutagen, 1993, 21(4), 357 - 64 Highly sensitive umu test system for the detection of mutagenic nitroarenes in Salmonella typhimurium NM3009 having high O-acetyltransferase and nitroreductase activities; Oda Y et al.; A highly sensitive umu test system for the detection of genotoxic activities of a variety of mutagenic nitroarenes has been developed using a new tester strain, Salmonella typhimurium NM3009 having high O-acetyltransferase (O-AT) and nitroreductase (NR) activities . The NM3009 was constructed by subcloning both the O-AT and NR genes into plasmid vector pACYC184, and the resulting plasmid was introduced into the parent tester strain S . typhimurium TA1535/pSK1002 harboring an umuC'-'lacZ fusion gene . The induction of umuC gene expression could be monitored by measuring the cellular beta-galactosidase activity produced by fusion gene . The purpose of the study was to evaluate whether the newly developed strain NM3009 is highly sensitive toward nitroarene compounds . The sensitivity of the strain NM3009 was compared with those of the parent TA1535/pSK1002 strain, the NR-overexpressing strain NM1011, the NR-deficient strain NM1000, the O-AT-overexpression strain NM2009, and the O-AT-defective strain NM2000 . The newly developed NM3009 strain had about 13-fold and 3-fold higher activities for N-AT and NR, respectively, than the original S . typhimurium TA1535/pSK1002 strain . Among six strains tested, NM3009 showed the highest sensitivity toward such chemicals as 1-nitronaphthalene, 2-nitrofluorene, 3,7-dinitrofluoranthene, 3-nitrofluoranthene, 5-nitroacenaphthene, 2-nitronaphthalene, 1-nitropyrene, 1,6-dinitropyrene, 3,9-dinitrofluoranthene, 4,4'-dinitrobiphenyl, 1,8-dinitropyrene, m-dinitrobenzene, 2,4-dinitrotoluene, and 1,3-dinitropyrene . We have also found that the order of sensitivities to induce umuC gene expression toward a variety of nitroarenes was NM3009 > NM2009 > NM1011 > TA1535/pSK1002 > NM2000 > NM1000 . These results suggest that the newly developed tester strain NM3009 is of great use for the detection of genotoxic activities of numerous carcinogenic and mutagenic chemicals including nitroarenes, which require NR and/or O-AT for the activation. Int Arch Occup Environ Health, 1993, 64(7), 473 - 7 Increases in polycyclic aromatic hydrocarbon content and mutagenicity in a cutting fluid as a consequence of its use; Apostoli P et al.; The aim of this study was to evaluate the relationships between the length of time a cutting fluid was used, its content in polycyclic aromatic hydrocarbons (PAHs) and its mutagenic potential . The PAH concentrations were determined by means of a high-resolution gas chromatograph-mass spectrometer in samples of new cutting fluid and in samples used for 3, 6 and 9 months . The following PAHs were measured: phenanthrene, anthracene, fluoranthene, pyrene, benzo{a}anthracene, chrysene+triphenylene, benzo{e}pyrene, benzo{a}pyrene and perylene . Mutagenicity assays were carried out on the aforementioned samples using the Ames test . Salmonella typhimurium TA98 was used as an indicator to show up mutagens capable of inducing frame-shift genetic changes, and Escherichia coli WP2 uvrA was used as an indicator to detect mutagens capable of inducing base pair genetic changes . The mutagenic tests were carried out with and without microsomal activation, using 1:1, 1:10, 1:20 and 1:50 dilutions of cutting fluid samples . An increase in the concentrations of total PAHs over time was observed in the samples of cutting fluid used for 3, 6 and 9 months . The highest percentage increase in PAH concentrations was observed in the 6-month-old sample (10 times the initial concentration, from 45 to 411.8 micrograms of oil) . None of the samples were mutagenic to S . typhimurium without metabolic activation or to E . coli with and without metabolic activation . All samples except for the 1:1 diluted sample showed moderate but significant mutagenic activity in the S . typhimurium test with metabolic activation.(ABSTRACT TRUNCATED AT 250 WORDS) Environ Mol Mutagen, 1993, 21(3), 253 - 7 Base-pair mutations caused by six aliphatic epoxides in Salmonella typhimurium TA100, TA104, TA4001, and TA4006; Einisto P et al.; Salmonella typhimurium strains TA100, TA104, TA4001, and TA4006 were used to detect the base-pair mutations caused by six aliphatic epoxides: chloropropylene oxide, glycidyl 1-naphthyl ether, glycidyl 4-nitrophenyl ether, 1-naphthyl-propylene oxide, styrene oxide, and trichloropropylene oxide . Dose-mutagenicity relationships could be established for all six epoxides in strains TA100 and TA104 but not in strains TA4001 and TA4006 . These results, together with the lack of sensitivity of the TA100 revertants to DL-1,2,4-triazole-3-alanine, indicate CG-->TA transitions and/or CG-->AT transversions are of major importance for mutations induced by these epoxides in Salmonella TA100 and possibly TA104 . In addition, since the reproducibility of the effect of the triazole on TA104 reversions was poor, TA-->AT transversions were not eliminated as also contributing to the mutagenicity of these epoxides in this Salmonella strain. Environ Mol Mutagen, 1993, 21(3), 247 - 52 Mutagenicity of iso-butyl nitrite vapor in the Ames test and some relevant chemical properties, including the reaction of iso-butyl nitrite with phosphate; Mirvish SS et al.; We examined the mutagenicity of iso-butyl nitrite (IBN) vapor and aqueous IBN solution in the Ames test to help evaluate the hazard of sniffing this vapor, a habit which might play a role in the induction of Kaposi's sarcoma associated with acquired immune deficiency syndrome . Chemical analysis showed that the saturated vapor contained 190 micrograms IBN/ml at 25 degrees C, and saturated aqueous solution, 2.6 mg IBN/ml at 21-23 degrees C . When agar plates containing Salmonella typhimurium TA-1535 and rat liver S-9 were exposed to IBN vapor, the number of mutants reached a maximum after 40 min . A mean of 307 mutants/plate (22 x background) was observed when the plates were exposed to IBN vapor for 30 min . Addition of 0.2 ml saturated IBN solution in water to similar plates gave a mean of 179 mutants/plate (7.9 x background) in the absence of S-9, confirming published results . The S-9 did not affect the results . Based on the IBN level in medium exposed to IBN vapor, the vapor was apparently 11 times more mutagenic than IBN solution . This was attributed to continuous replenishment of unstable IBN in the medium by the vapor . The half-life of IBN at 21-23 degrees C was > 1 hr for solutions in water and < 3 min for solutions in the assay medium . This instability was traced to a reaction with phosphate, presumably hydrolysis to nitrite and iso-butanol . IBN in solution was 2.8 times more mutagenic than sodium nitrite, suggesting that IBN was not mutagenic because of its conversion to nitrite . Iso-butanol was not mutagenic . The results demonstrate the potential hazard of sniffing IBN vapor. Environ Mol Mutagen, 1993, 21(3), 237 - 46 Formation and characterization of bacterial mutagens from reaction of the alternative disinfectant monochloramine with model aqueous solutions of fulvic acid; Cozzie DA et al.; Monochloramine has been suggested as an alternative disinfectant to chlorine to reduce levels of trihalomethanes in treated drinking water, but little is known of the toxicological properties and potential health implications of by-products specific to the chloramination process . Model aqueous fulvic acid solutions (200-400 mg C/liter), serving as surrogates for humic surface waters, were chloraminated over a range of molar Cl:C ratios from 1:40 to 1:2 . The resulting by-products were extracted into diethyl ether at pH 2 and investigated with the Ames plate incorporation assay . Extractable mutagenicity increased with increasing chlorine and carbon dose up to about 30,000 revertants/liter at Cl:C ratios of 1:2 . Mutagenicity was higher in Salmonella typhimurium strain TA100 than in strain TA98, and was decreased in the presence of S9, indicating that the mutagens formed were direct-acting and induced predominantly base-pair substitutions . Bovine serum albumin decreased slightly, and glutathione reduced greatly, the mutagenic activity detected in extracts . HPLC fractionation of the by-products indicated that most of the mutagenic activity was found in the earliest-eluting (most polar) fraction . The mutagenic by-products appeared to be qualitatively similar to 3-chloro-4-dichloromethyl-5-hydroxy-2-(5H)-furanone (MX) in their chromatographic behavior and responses to glutathione and bovine serum albumin, but were less readily detoxified by S9 than was MX. Environ Mol Mutagen, 1993, 21(3), 219 - 28 Genotoxicity of volatile and secondary reactive oxygen species generated by photosensitization; Camoirano A et al.; Reactive oxygen species were generated in the gas phase by photosensitization involving illumination of Rose Bengal . Depending on whether the chromophore is dry or solubilized, this system produces either energy-transfer reactions leading to generation of singlet oxygen specifically, or a combination of energy-transfer and electron-transfer reactions, providing both singlet oxygen and reduced forms of oxygen, such as superoxide anion and hydrogen peroxide . In neither case were the reactive species mutagenic in strain TA104 of Salmonella typhimurium, which had been previously shown to be reverted by oxygen species generated by the hypoxanthine-xanthine oxidase system in aqueous medium . However, mixed oxygen species induced an increased lethality in a variety of DNA repair-deficient Escherichia coli strains . This genotoxic effect, mainly reparable by the uvrA and recA mechanisms, was efficiently prevented by the thiol N-acetyl-L-cysteine . Singlet oxygen itself failed to exert direct genotoxic effects, although secondary reactants produced by its reaction with cell components enhanced lethality in some repair-deficient bacteria . Distance-dependence analyses provided measurements of the lifetimes of the oxygen species generated in the gas phase. Avian Dis, 1993 Jan-Mar, 37(1), 183 - 8 Control of established Salmonella typhimurium intestinal colonization with in vivo-passaged anaerobes; Ziprin RL et al.; Broiler chickens were inocul