Appl Environ Microbiol, 1989 Dec, 55(12), 3221 - 5 Substrate interactions during aerobic biodegradation of benzene; Arvin E et al.; This study dealt with the interactions with benzene degradation of the following aromatic compounds in a mixed substrate: toluene, o-xylene, naphthalene, 1,4-dimethylnaphthalene, phenanthrene, and pyrrole . The experiment was performed as a factorial experiment with simple batch cultures . The effect of two different types of inocula was tested . One type of inoculum was grown on a mixture of aromatic hydrocarbons; the other was grown on a mixture of aromatic hydrocarbons and nitrogen-, sulfur-, and oxygen-containing aromatic compounds (NSO compounds), similar to some of the compounds identified in creosote waste . The culture grown on the aromatic hydrocarbons and NSO compounds was much less efficient in degrading benzene than the culture grown on only aromatic hydrocarbons . The experiments indicated that toluene- and o-xylene-degrading bacteria are also able to degrade benzene, whereas naphthalene-, 1,,4-dimethylnaphthalene-, and phenanthrene-degrading bacteria have no or very little benzene-degrading ability . Surprisingly, the stimulating effect of toluene and o-xylene was true only if the two compounds were present alone . In combination an antagonistic effect was observed, i.e., the combined effect was smaller than the sum from each of the compounds . The reason for this behavior has not been identified . Pyrrole strongly inhibited benzene degradation even at concentrations of about 100 to 200 micrograms/liter . Future studies will investigate the generality of these findings. J Biomed Mater Res, 1989 Dec, 23(A3 Suppl), 363 - 80 An histo-morphological evaluation of ninety surgically excised human umbilical vein grafts; Gill F et al.; Morphological, histological, and scanning electron microscopy examinations were performed on 90 surgically excised human umbilical vein grafts . Most of the explanted grafts were removed because of thrombosis or infection and were removed typically from a patient in the mid 60s and after an average duration of implantation of 11 months . Multiple structural defects were found including deep folds, breaks on the luminal surface, and delamination . These areas as well as anastomotic sites represented potential areas for thrombotic accumulation . A higher incidence of infection was observed in grafts composed of 2 or 3 segments . Bacteria were often found in folds and could be seen invading the wall of the prosthesis . In addition, bacteremic colonization was often seen in noninfected grafts . The late aneurysmal formations were also of particular concern . The biodegradation of the wall and the disruption of the polyester mesh were the probable causes . The second generation Dardik Biograft aimed at reducing these formations . The success of this new processing remains to be evaluated. Ecotoxicol Environ Saf, 1989 Dec, 18(3), 252 - 67 Expert systems survey on biodegradation of xenobiotic chemicals; Boethling RS et al.; To determine the feasibility of developing an expert system for biodegradability assessment, a survey was conducted in which biodegradation experts were asked to estimate rates and products of degradation for 50 chemicals . These chemicals, which varied widely in structure, were considered representative of the spectrum of premanufacture notice chemicals subject to EPA review under the Toxic Substances Control Act . There was substantial agreement among the 22 experts on both sites of initial attack and rates of degradation . The approximate order in which various groups were viewed as contributing to aerobic biodegradability is as follows: ester, amide, anhydride greater than hydroxyl greater than carboxyl, epoxide, site of unsaturation greater than benzene ring, methyl, methylene . Hydrolyzable groups, azo bonds, halogens, and nitro groups were preferred sites of anaerobic attack . Among the negative influences on aerobic biodegradability were molecular mass, branching, halogenation, and nitrogen heterocycles . Results also indicate that estimates of removal by biodegradation in aerobic wastewater treatment and time for aerobic ultimate and primary degradation were well correlated, and that the predictive value of such correlations could be improved using correction factors for certain classes of chemicals . The results lend support to existing rules of thumb, but also offer additional insight that will prove useful in designing a prototype system. Appl Environ Microbiol, 1989 Dec, 55(12), 3155 - 61 Biodegradation of trichloroethylene by Methylosinus trichosporium OB3b; Tsien HC et al.; The methanotroph Methylosinus trichosporium OB3b, a type II methanotroph, degraded trichloroethylene at rates exceeding 1.2 mmol/h per g (dry weight) following the appearance of soluble methane monooxygenase in continuous and batch cultures . Cells capable oxidizing trichloroethylene contained components of soluble methane monooxygenase as demonstrated by Western blot (immunoblot) analysis with antibodies prepared against the purified enzyme . Growth of cultures in a medium containing 0.25 microM or less copper sulfate caused derepression of the synthesis of soluble methane monooxygenase . In these cultures, the specific rates of methane and methanol oxidation did not change during growth, while trichloroethylene oxidation increased with the appearance of soluble methane monooxygenase . M . trichosporium OB3b cells that contained soluble methane monooxygenase also degraded vinyl chloride, 1,1-dichloroethylene, cis-1,2-dichloroethylene, and trans-1,2-dichloroethylene. FEMS Microbiol Lett, 1989 Nov, 53(1-2), 37 - 40 Increased expression of biodegradative threonine dehydratase of Escherichia coli by DNA gyrase inhibitors; Sumantran VN et al.; The synthesis of inducible biodegradative threonine dehydratase of Escherichia coli increased several-fold in the presence of the DNA gyrase inhibitors, nalidixic acid and coumermycin . Temperature-sensitive gyrB mutants expressed higher levels of dehydratase as compared to an isogenic gyrB+ strain . Immunoblotting experiments showed increased synthesis of the dehydratase protein in the presence of gyrase inhibitors; addition of rifampicin and chloramphenicol to cells actively synthesizing enzyme preventing new enzyme production . Increased expression of dehydratase by gyrase inhibitors was accompanied by relaxation of supercoiled DNA. J Urol, 1989 Sep, 142(3), 837 - 45 Growth and differentiation of the gubernaculum testis during testicular descent in the pig: changes in the extracellular matrix, DNA content, and hyaluronidase, beta-glucuronidase, and beta-N-acetylglucosaminidase activities; Fentener van Vlissingen JM et al.; The gubernaculum testis is a loose connective tissue organ that plays an essential mechanical role in testicular descent . In the pig, the first phase of descent (transabdominal migration) is brought about by growth of the gubernaculum through the inguinal canal into the scrotum and simultaneous somatic growth of the fetus . During the second phase the gubernaculum condenses, thus allowing the testis to descend into the scrotum . The nature of gubernaculum development (growth and differentiation) was investigated with respect to cell proliferation, extracellular matrix (ECM) composition, and acid hydrolases . Deoxyribonucleic acid (DNA) was used as a measure of cell number and hydroxyproline (HYP) was an estimate of interstitial collagen . The first phase of gubernaculum development was characterized by rapid cell proliferation and concomitant synthesis of sulphated glycosaminoglycans (S-GAG), hyaluronic acid (HA) and collagen . During the second phase cell proliferation ceased and DNA concentration increased . The amount of S-GAG remained closely related to the amount of DNA while HYP increased further . However, HA decreased during the second phase and thus HA metabolism seems to play a crucial role in biphasic development of the gubernaculum . The activities of the enzymes that are needed for biodegradation of HA (hyaluronidase, beta-glucuronidase and beta-N-acetylglucosaminidase) were measured in gubernaculum homogenate from animals during the first and second phase of testicular descent . These enzymes were detectable in gubernaculum and rose during the second phase of testicular descent . It was concluded that a very distinct dichotomy in the nature of gubernaculum development during the first and second phase could be discerned with respect to cell proliferation rate and ECM synthesis and degradation . These observations provide useful tools for future in vivo and in vitro investigations into the process and regulation of testicular descent. Biol Chem Hoppe Seyler, 1989 Sep, 370(9), 1019 - 26 Biodegradability of synthetic branched polypeptide with poly(L-lysine) backbone; Hudecz F et al.; A detailed investigation is reported about the biodegradation of poly{Lys(DL-Alam)}, m approximately 3, (AK) the common inside area of a branched polypeptide model system developed by our group over the last decade . Enzymatic hydrolysis was carried out by the exopeptidase aminopeptidase M, or the endopeptidase trypsin, or their mixture . Ion-exchange column chromatography, paper electrophoresis and thin-layer chromatography were utilised to achieve separation of metabolites . Breakdown products were identified by the aid of synthetic oligopeptides representing the potential fragments (DL-Ala2, DL-Ala3, Lys(DL-Alam), m = 1-3) . The kinetics and the degree of enzymatic degradation were determined . The ratio of peptide/amino acid amounts in the hydrolysate was found to be 1.07 after 24 h treatment with aminopeptidase M, 3.0 with trypsin and 1.3 with aminopeptidase - trypsin mixture . The overall results indicated that the proteolysis of AK by an aminopeptidase M and trypsin mixture proceeds stepwise at multiple sites on the polypeptide chain . The degradation is significantly retarded as compared to that of alpha- or epsilon-polylysine . A mechanism of degradation is suggested based on the experimental results. Mol Gen Genet, 1989 Sep, 218(3), 516 - 22 Identification and DNA sequence of tdcR, a positive regulatory gene of the tdc operon of Escherichia coli; Schweizer HP et al.; Efficient in vivo expression of the biodegradative threonine dehydratase (tdc) operon of Escherichia coli is dependent on a regulatory gene, tdcR . The tdcR gene is located 198 base pairs upstream of the tdc operon and is transcribed divergently from this operon . The nucleotide sequence of tdcR and two unrelated reading frames has been determined . The deduced amino acid sequence of TdcR indicates that it is a polypeptide of Mr 12,000 with 99 amino acid residues and contains a potential helix-turn-helix DNA binding motif . Deletion analysis and minicell expression of the tdcR gene suggest that TdcR may serve as a trans-acting positive activator for the tdc operon. Chem Pharm Bull (Tokyo), 1989 Aug, 37(8), 2245 - 7 Synthesis of macromolecular prodrugs of procaine, histamine and isoniazid; Giammona G et al.; The attachment of various drugs bearing -NH2 groups to poly-alpha,beta-aspartic acid as a biodegradable carrier afforded in good yields macromolecular prodrugs which were characterized with respect to composition and drug load by spectroscopic and analytical methods . N-Ethyl-N'-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) in an aqueous medium proved to be useful in the attachment reaction . Isoniazid, procaine and histamine were covalently coupled as pendant groups onto poly-alpha,beta-aspartic acid via an amide bond . In principle, controlled release of the aforementioned drugs can be achieved by biodegradation of the polymer or by cleavage of covalently bound polymer-drug conjugates. Br J Anaesth, 1989 Jul, 63(1), 103 - 8 Ethanol-inducible cytochrome P450 in rabbits metabolizes enflurane; Hoffman J et al.; Following anaesthesia with enflurane, some patients receiving isoniazid have increased serum concentrations of fluoride ion, presumably because of induction of an isozyme of cytochrome P450 which is responsible for enflurane biodegradation . In rats, isoniazid and ethanol enhance metabolism of enflurane and also induce a form of cytochrome P450 which is homologous with a form of rabbit liver cytochrome P450 known as 3a . Isoniazid, ethanol and imidazole increase the concentration of cytochrome P450 3a in hepatic microsomes . We have pretreated rabbits with imidazole, the most potent of the three inducers of isozyme 3a, to determine if the hepatic microsomal metabolism of enflurane is enhanced and if purified isozyme 3a catalyses the oxidation of enflurane . Imidazole produced a 250% increase in the hepatic microsomal metabolism of enflurane, sevoflurane, methoxyflurane and the control substrate, aniline . Polyclonal antibodies to cytochrome P450 3a inhibited 90% of enflurane metabolism, but only 40% of methoxyflurane biotransformation in the microsomes from imidazole-pretreated rabbits . Thus isozyme 3a or a structurally similar cytochrome P450 seemed to catalyse almost all microsomal metabolism of enflurane . In addition, purified cytochrome P450 3a catalysed the metabolism of enflurane, sevoflurane and methoxyflurane, and the oxidation of these anaesthetics by cytochrome P450 3a was stimulated four-fold by cytochrome b5, a protein which serves as an alternate source of electrons for some cytochrome P450 reactions. J Steroid Biochem, 1989 Jul, 33(1), 141 - 6 Testosterone metabolism in neuroendocrine organs in male rats under atrazine and deethylatrazine influence; Babic-Gojmerac T et al.; The inhibitory influence of atrazine and deethylatrazine on testosterone metabolism in male rat anterior pituitary and hypothalamus were studied under in vivo and in vitro experimental conditions . In vivo strong influence of atrazine (12 mg/100 g by wt . daily during 7 days) on 5 alpha-R, 3 alpha- and 17 beta-HSD activities was detected in the anterior pituitary . This dose provokes a significant increase in the weight of the pituitary gland, with hyperemia and hypertrophy of chromophobic cells with vacuolar degeneration . In vivo treatment of male rats with the same dose of deethylatrazine markedly inhibited 5 alpha-R activity in the anterior pituitary . The rate of 5 alpha-R activity inhibition in the anterior pituitary was the same after in vivo treatment with atrazine (37.3%) as with deethylatrazine (33.9%) . This could suggest that the mechanism of inhibition of deethylatrazine is similar to that of atrazine . In vitro atrazine or deethylatrazine addition into the incubation medium significantly (P less than 0.01) inhibited 5 alpha-R, 3 alpha- and 17 beta-HSD activities in the anterior pituitary . The inhibition of 5 alpha-R activity was marked more by atrazine than deethylatrazine, while 3 alpha- and 17 beta-HSD activities were inhibited at the same rate . In vivo treatment with the same dose of atrazine or deethylatrazine (12 mg/100 g by wt daily 7 days) significantly inhibited (P less than 0.01) 5 alpha-R and 17 beta-HSD at the male rat hypothalamic level . 3 alpha-HSD activity inhibition was not significant for either compound . The in vitro addition of deethylatrazine was much more effective (P less than 0.01) in inhibiting 5 alpha-R, 3 alpha- and 17 beta-HSD in male rat hypothalamus than atrazine . In spite of this, deethylatrazine seems to be less toxic in in vivo experiments due to its higher polarity and faster biodegradation. J Pharm Pharmacol, 1989 Jul, 41(7), 433 - 8 Biodegradation rate of embolized protein microspheres in lung, liver and kidney of rats; Willmott N et al.; The targeting and sustained release characteristics of cytotoxic drug-loaded protein microspheres may prove useful in the therapeutic chemoembolization of solid tumours . Because biodegradation rate of embolized particles will influence rate of incorporated drug release and duration of exposure, this parameter was studied for microspheres (10-30 microns mean diam.) prepared from the proteins albumin and casein, that we have previously used as carriers for doxorubicin . As a measure of microsphere loss in-vivo the radionuclide 125I was chosen because it can be covalently bound to proteins and also homogeneously distributed throughout the matrix . Radiolabelled microspheres were administered to rats both intravenously (lung as target organ, 1.4-2.2 mg/100 g) and via the hepatic artery (liver as target organ, 0.4-0.8 mg/100 g) . In both cases it was observed that the casein system biodegraded more slowly than the albumin in-vivo . Thus, time taken for loss of 50% of embolized microspheres from lung was: albumin 2.0 days; casein 3.5 days and from liver:albumin 3.6 days; casein 6.8 days . Microsphere "debris" did not markedly accumulate in other organs . In-vitro experiments showed that microspheres were stable in serum and that albumin microspheres were not innately more sensitive to enzymic digestion than casein . The results may be useful in estimating duration of exposure of target organs to drug-loaded microsphere systems prepared from these proteins. J Bacteriol, 1989 Jun, 171(6), 3379 - 84 Amino acid sequence of the regulatory-site glyoxylate peptide of biodegradative threonine dehydratase of Escherichia coli; Patil RV et al.; Incubation of purified Escherichia coli biodegradative threonine dehydratase with glyoxylate resulted in covalent binding of 1 mol of glyoxylate per mol of protein with concomitant loss of enzyme activity . The glyoxylate-binding site was identified as a heptapeptide representing amino acid residues Ser-33-Asn-Tyr-Phe-Ser-Glu-Arg-39 in the protein primary structure . Addition of glyoxylate to a culture of E . coli cells led to time-dependent enzyme inactivation . Immunoprecipitation with anti-dehydratase antibody of extract from {14C}glyoxylate-treated cells revealed labeled dehydratase polypeptide . These results are interpreted to mean that enzyme inactivation by glyoxylate in E . coli cells is associated with covalent protein modification. Biotechnol Appl Biochem, 1989 Jun, 11(3), 318 - 27 Metabolic pathway for the biodegradation of sodium dodecyl sulfate by Pseudomonas sp . C12B; Thomas OR et al.; Metabolism of sodium dodecyl sulfate (SDS) by the detergent-degrading bacterium Pseudomonas C12B has been studied using a 14C radiotracer in combination with radio-respirometry, radio-TLC, and GLC . Metabolism was extensive with 70% of the radiolabel released as 14CO2 at completion . The remainder of the radiolabel was incorporated almost totally into cells . Ether extraction of cells indicated that 14C-labeled cellular material appearing early in the uptake process was predominantly ether-extractable (mainly 1-dodecanol) and was subsequently converted to more polar metabolites . Analysis of the extractable lipids established the sequential production from {1-14C}SDS of 1-dodecanol, dodecanal, and dodecanoic acid . At this point the pathway diverged leading either to formation of 14CO2 via beta-oxidation or to elongation to C14, C16, and C18 fatty acyl residues with rapid incorporation into lipid fractions such as phospholipids . The pathway was correlated with known long-chain alkylsulfatases and alcohol dehydrogenases in this isolate and indicated that hydrophobic metabolites of the alkyl chain of surfactants can be incorporated into cellular components such as membrane lipids without prior degradation by beta-oxidation. J Oral Maxillofac Surg, 1989 May, 47(5), 480 - 8 Zygomatic and mandibular augmentation with proplast and porous hydroxyapatite in rhesus monkeys; el Deeb M et al.; Using an extraoral approach, subperiosteal pockets were created bilaterally over the zygomatic and mandibular regions in six Rhesus monkeys . One side of each animal received a Proplast I (Vitek Inc, Houston) implant and the contralateral side received an equivalent sized block of porous hydroxyapatite (HA) . The animals were followed clinically and radiographically . Two animals were killed postoperatively at 3, 6, and 12 months, respectively . The implants were retrieved en bloc and halved . Half of each specimen was decalcified, embedded in paraffin, and stained . The other half was embedded in plastic, and sections were stained or carbon-coated for histometry scanning under electron microscopy . Clinical evaluation revealed that porous HA implants were more stable than Proplast implants . The Proplast implants showed complete encapsulation by infiltration with fibrovascular connective tissue, and progressive fragmentation with giant cell reactions . The porous HA implants were united to the underlying cortex by bony ingrowth . The volume of implants sampled within 2.5 mm of the underlying cortex contained 42.5% HA matrix and 23.8% bony ingrowth, and the surface area of the HA matrix (9.7 mm2/mm3) was 47.8% covered by bony ingrowth . No giant cell response, fragmentation, or biodegradation was observed or measured in the porous HA implants . The data from this primate model further substantiate previous canine studies and permit more reliable estimation of clinical performance . These results provide comparative data that can contribute to the decision-making process in selecting clinical implants. Mol Microbiol, 1989 May, 3(5), 609 - 20 Construction of lac fusions to the inducible arginine- and lysine decarboxylase genes of Escherichia coli K12; Auger EA et al.; The induction of several amino acid decarboxylases under anaerobic conditions at low pH has been known for many years, but the mechanism associated with this type of regulation has not been elucidated . To study the regulation of the biodegradative arginine and lysine decarboxylases of Escherichia coli K12, Mudlac fusions to these genes were isolated . Mudlac fusion strains deficient for lysine decarboxylase or arginine decarboxylase were identified using decarboxylase indicator media and analysed for their regulation of beta-galactosidase expression . The position of the Mudlac fusion in lysine decarboxylase-deficient strains has been mapped to the cadA gene at 93.7 minutes, while the Mudlac fusions exhibiting a deficiency in the inducible arginine decarboxylase have been mapped to 93.4 minutes. Genetika, 1989 Apr, 25(4), 581 - 94 {Genetic systems of biodegradation: organization and regulation of expression}; Boronin AM et al.; The review discusses the current state of genetic analysis of degradative processes . Attention is mainly given to the structural and functional organization of the plasmid systems of degradation of organic compounds in gram-negative bacteria . The data available on the regulation mechanisms of D plasmids' metabolic operons, based on the most studied models of xyl and nah operons, are critically analyzed . The problems of evolution of plasmid D systems are considered conceptually as well as the principles of the experimental strategy of developing new metabolic pathways under laboratory conditions . The prospects of constructing the strains capable of efficient degradation of xenobiotics are considered in brief. Biochim Biophys Acta, 1989 Mar 28, 1011(1), 12 - 7 Evidence of a new metabolic pathway of 5-fluorouracil in Escherichia coli from in vivo 19F-NMR spectroscopy; Lee KR et al.; Two distinct metabolic pathways of 5-fluorouracil are proposed in Escherichia coli . The first metabolic pathway is a reductive degradation with the formation of dihydrofluorouracil as the first metabolite . The second metabolic pathway is shown to be a hydroxylating degradation, possibly with the formation of 5-hydro-6-hydroxy-5-fluorouracil as the first metabolite . The metabolites of both pathways undergo subsequent hydrolytic degradation with fluoride ion as the common final product . The chemical structures of these metabolites were partially identified by 19F-NMR . The results show a close resemblance between these two metabolic pathways with in vivo pyrimidine biodegradation . The reductive degradation has been proposed by several laboratories, whereas the hydroxy degradation has not been reported before . Both the reductive and hydroxy pathways are demonstrated in this report, to be independent reactions. Biochem J, 1989 Mar 15, 258(3), 709 - 13 Characterization of difluoromethylornithine-resistant mouse and human tumour cell lines; Hirvonen A et al.; Four mouse and two human tumour cell lines resistant to alpha-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase (ODC), were analysed for the activities of polyamine-biosynthetic and -biodegradative enzymes as well as for cellular polyamine contents . In all but one of these cell lines the resistance to DFMO was based on an overproduction of ODC . In a human myeloma cell line the resistance was based on a greatly enhanced arginase activity . Except for one L1210 variant cell line, all the resistant cell lines contained elevated S-adenosylmethionine decarboxylase activity . Similarly, all the resistant mouse, but not human, cell lines displayed enhanced spermidine and spermine synthase activities . Arginase activity was detected only in human cell lines . In both DFMO-resistant cell lines the activity of arginase was strikingly elevated . Of the biodegradative enzymes, polyamine oxidase activity was readily detectable in all mouse cells, but no measurable activity was found in the human cells . Spermidine/spermine N1-acetyltransferase activity was elevated in three out of four resistant mouse cell lines . Even though the concentration of spermidine was usually lower in the overproducer cells, this was compensated by an increased content of spermine . The two resistant human myeloma cells contained intracellular ornithine concentrations that were from more than 5 to more than 20 times higher than those in the parental cells. Biofactors, 1989 Mar, 2(1), 17 - 25 The herbicide glyphosate; Malik J et al.; Glyphosate has broad spectrum herbicidal activity against a wide range of annual and perennial weeds . The environmental properties of this herbicide such as its soil immobility, rapid soil inactivation and soil biodegradation are outstanding . This herbicide is practically non-toxic to non-plant life forms such as aquatic and avian species, animals and man . Metabolism studies with pure bacterial cultures indicate that glyphosate is metabolized to either aminomethylphosphonate and glyoxylate or sarcosine and phosphate in most bacteria . The enzyme C-P lyase, which catalyzes the cleavage of the carbon-phosphorus bond of phosphonates including glyphosate, appears to be complex, containing multiple subunits . Mode of action studies have demonstrated that glyphosate kills plants by inhibiting the enzyme 5-enolpyruvylshikimate-3-phosphate synthase, involved in the biosynthesis of aromatic compounds . The status of our understanding of these aspects of glyphosate is reviewed. Ukr Biokhim Zh, 1989 Mar-Apr, 61(2), 114 - 8 {Interaction of block-polyurethane containing lactose linkages and immobilized beta-galactosidase with body tissues}; Shevchenko OS et al.; Biodegradation of the polymeric composition containing immobilized beta-galactosidase after implantation and its effect on the surrounding tissues are examined . Immunogenicity of the composition is studied by the method of the immunoenzymic analysis . Activation of the immune system is shown to occur in the process of the composition degradation. J Oral Maxillofac Surg, 1989 Feb, 47(2), 142 - 6 The use of a pedicled temporalis muscle-pericranial flap for replacement of the TMJ disc: preliminary report; Feinberg SE et al.; Disc replacement in temporomandibular joint surgery has been troublesome . Problems such as migration, fragmentation, foreign body reactions, and unpredictable biodegradation have occurred . Autogenous tissue is presently the material of choice, but requires a second surgical site . In addition, it is a free graft, and thus its fate is unknown . A technique has been developed that uses a pedicled autogenous flap composed of a portion of the temporalis muscle and pericranium to act as an interpositional material in temporomandibular joint surgery . The flap, based on the deep temporal arteries, and pedicled off of the coronoid process, is rotated anterior to the articular eminence and then posteriorly into the temporomandibular joint where it is sutured to the retrodiscal tissue . This procedure allows maintenance of tissue viability and functional movement of the flap during mandibular excursions . The technique offers numerous advantages over the existing autogenous, allogeneic, and alloplastic materials presently used in temporomandibular joint surgery. Appl Environ Microbiol, 1989 Feb, 55(2), 348 - 53 Anaerobic biodegradation of 2,4-dichlorophenol in freshwater lake sediments at different temperatures; Kohring GW et al.; Anaerobic degradation of 2,4-dichlorophenol (2,4-DCP) between 5 and 72 degrees C was investigated . Anaerobic sediment slurries prepared from local freshwater pond sediments were partitioned into anaerobic tubes or serum vials, which then were incubated separately at the various temperatures . Reductive 2,4-DCP dechlorination occurred only in the temperature range between 5 and 50 degrees C, although methane was formed up to 60 degrees C . In sediment samples from two sites and at all tested temperatures from 5 to 50 degrees C, 2,4-DCP was transformed to 4-chlorophenol (4-CP) . The 4-CP intermediate was subsequently degraded after an extended lag period in the temperature range from 15 to 40 degrees C . Adaptation periods for 2,4-DCP transformation decreased between 5 and 25 degrees C, were essentially constant between 25 and 35 degrees C, and increased in the tubes incubated at temperatures between 35 and 40 degrees C . The degradation rates increased exponentially between 15 and 30 degrees C, had a second peak at 35 degrees C, and decreased to about 5% of the peak activity by 40 degrees C . In tubes from one sediment sample, incubated at temperatures above 40 degrees C, an increase in the degradation rate was observed following the minimum at 40 degrees C . This suggests that at least two different organisms were involved in the transformation of 2,4-DCP to 4-CP . Storage of the original sediment slurries for 2 months at 12 degrees C resulted in increased adaptation times, but did not affect the degradation rates. Sci Total Environ, 1989 Feb, 79(1), 1 - 23 Environmental impact of used motor oil; Vazquez-Duhalt R; The information concerning the effects of used motor oil on the environment is reviewed . The production and fate of used motor oil are analyzed and the effects on soil and aquatic organisms are described . The combustion of waste crankcase oil, with particular reference to environmental impact, is discussed . The mutagenic and carcinogenic effects of used motor oil are described . Information on the biodegradation of lubricating motor oil is also reviewed . The available information shows that used motor oil is a very dangerous polluting product . As a consequence of its chemical composition, world-wide dispersion and effects on the environment, used motor oil must be considered a serious environmental problem. Ecotoxicol Environ Saf, 1989 Feb, 17(1), 119 - 30 Biodegradation kinetics of linear alkylbenzene sulfonate in sludge-amended agricultural soils; Ward TE et al.; The kinetics of ultimate biodegradation (mineralization to CO2) of linear alkylbenzene sulfonate (LAS) were studied in sludge-amended agricultural soils for a series of pure chain length LAS homologs containing 10 to 14 carbon atoms in the alkyl chain . Degradation rates were measured by following the production of 14CO2 from uniformly 14C-ring-labeled material . In general, degradation of LAS was rapid in soil over a broad concentration range (0.1 to 10 times the expected environmental concentration) and demonstrated little variation among different homologs . Half-lives for mineralization of the benzene ring ranged from 18 to 26 days and were not significantly different for any homolog over the range of alkyl chain lengths tested . Half-lives measured for LAS degradation in these studies were comparable to values reported in the literature and also to values obtained for naturally occurring materials (stearic acid, cellulose) typically present in soil environments . On the basis of the results of the present studies and those of other investigators, it is concluded that soil environments exposed to LAS in sewage sludges contain microbial communities which can actively metabolize this material . Rates of biodegradation of the benzene ring, the final step in the LAS biodegradation pathway prior to complete mineralization, are also sufficient to prevent LAS from accumulating in soil environments. J Pharmacol Exp Ther, 1989 Jan, 248(1), 400 - 14 Neurochemical profile of moclobemide, a short-acting and reversible inhibitor of monoamine oxidase type A; Da Prada M et al.; Moclobemide belongs to a new generation of short-acting, reversible, monoamine oxidase (MAO) inhibitors . In vitro (rat brain homogenates) moclobemide inhibits MAO-A selectively with lower potency than many of the reference MAO inhibitors . However, when measured ex vivo in the rat, the potency of moclobemide is similar to that of reference compounds . In vivo the drug induces a dose-dependent, short-lasting (8-16 hr) and preferential inhibition of MAO-A in the brain and both MAO-A and MAO-B inhibition in extracerebral organs (liver, small intestine and kidney) . In the extracerebral tissues of the rat moclobemide induces marked peripheral MAO-B inhibition due to rapid and extensive biotransformation of its morpholine ring . The active molecular species is probably the metabolite Ro 16-6491 . The moderate MAO-B inhibition measured after moclobemide intake in human platelets indicates that only minor amounts of Ro 16-6491 are formed in humans . Virtually all metabolites of moclobemide so far identified have been tested in vitro and ex vivo in the rat and proved to be either equipotent or, mostly, less effective than moclobemide as MAO-A inhibitors . In liver homogenates of moclobemide-treated rats MAO-A activity recovers during dialysis or simple incubation at 37 degrees C, suggesting a biodegradation of moclobemide and/or the moclobemide-derived active metabolite(s) by MAO itself or a slow dissociation of the active inhibitory species from the enzyme . Similar to other MAO-A inhibitors, moclobemide induces an increase in the rat brain levels of 5-hydroxytryptamine, norepinephrine and dopamine and a concomitant decrease of their deaminated metabolites . These effects are of short duration (8-16 hr) and parallel the time course of MAO-A inhibition . Moclobemide administered subchronically down-regulates beta adrenoceptors as shown by binding experiments with brain cortical membranes using dihydroalprenolol as ligand . In vitro MAO inhibition by moclobemide is specific in that the compound does not affect other amine oxidases or monoamine uptake mechanisms; furthermore, it does not interact with various neurotransmitter or drug receptor sites . In conclusion, a large body of preclinical evidence characterizes moclobemide as a short-acting and reversible MAO-inhibitor . The neurochemical profile of moclobemide indicates clearly that this nonhydrazine nonhepatotoxic MAO-A inhibitor represents a novel and safe drug for treatment of affective disorders. Arthroscopy, 1989, 5(3), 165 - 71 Arthroscopic follow-up of anterior cruciate ligament reconstruction using allogeneic tendon; Shino K et al.; We have made a long-term arthroscopic study of anterior cruciate ligament (ACL) reconstructions using cryopreserved allogeneic tendon in 49 knees . Not only the reconstructed ACL itself, but also the entire joints were arthroscopically evaluated from 18 through 59 months postoperatively . Physical examinations at the arthroscopic follow-up revealed that Lachman's sign was negative in 45 and mildly positive in 4 patients and that the pivot-shift sign was negative in 46 and mildly positive in 3 patients . ACL grafts did not show any biodegradation with time but maintained a thick and viable appearance, although 3 of the taut ones showed partial necrosis in the anterolateral part . Fibrillation of the patellofemoral articular surface was commonly found, although no patients complained of anterior knee pain . Degenerative changes were usually found in those patients who had resumed strenuous activity without their menisci being intact . Follow-up arthroscopy was useful for monitoring the overall structures inside the post-operative knees, enabling us to persuade the patients to regulate their activity on the basis of objective evidence. Fortschr Ophthalmol, 1989, 86(3), 192 - 4 {Clinical experiences with a therapeutic collagen contact lens}; Pillunat LE et al.; In 43 eyes of 40 patients, the therapeutic effects of a self-dissolving hydrophilic collagen contact lens were investigated . Epithelial defects of any source, lamellar perforating corneal injuries, and trophic sterile corneal ulcers were defined as indications for the use of the lens . Collagen contact lenses were applied with biodegradation times of 6, 24, and 72 h . All patients tolerated the lens well, and no adverse reactions to the collagen material were observed . In all diseases where the lens was applied, re-epithelialization was found to be relatively fast. Cancer Chemother Pharmacol, 1989, 24(4), 238 - 42 The effect of structural modifications of 5-fluorouracil derivatives on their transport and biodegradation by isolated rat jejunum; Novotny L et al.; The continuous-perfusion technique was used in an isolated segment of everted rat jejunum to study transport and biotransformation processes in a series of cancerostatic derivatives of 5-fluorouracil . Metabolic alterations during penetration of the intestinal wall were assessed by high-performance liquid chromatography (HPLC) . Octanol-buffer partition coefficients were measured, and the lipophilicity of the study compounds and fragmental constants for their sugar moieties were assessed . In the present series of 5-fluorouracil derivatives, there was no correlation between lipophilicity and metabolic cleavage to 5-fluorouracil, but a correlation was found between lipophilicity and the transport rate . Remarkable stability of the nucleoside bond and high biotransport were observed with 5'-chloro-5-fluorouridine, suggesting a different mode of activation for this derivative. Neoplasma, 1989, 36(3), 257 - 72 Theoretical study of N-nitrosoureas and mechanism of their carcinogenic effect; Frecer V et al.; A mechanistic study into the carcinogenic action of N-nitrosoureas (NU) was carried out with the aid of the semiempirical MINDO/3 method . The proposed reaction pathways of NU biodegradation mechanisms were examined and the most probable one was identified on the ground of theoretical considerations . The calculations of reaction enthalpies confirmed NU as SN1 reagents . The reactivity of a series of NU molecules (both isolated and under the solvent influence) were studied with respect to the detection of possible determinants of the relative carcinogenic potency . The correlations revealed a key function of the nitrosogroup and of the N3-C7 fragment in the decomposition process . The role of the transport properties and lipophilicity of parent NU molecules in the initial steps of the mechanism of carcinogenic effects was demonstrated as well. Schriftenr Ver Wasser Boden Lufthyg, 1989, 80, 91 - 117 Biodegradation of crude oils; Bosecker K et al.; Petroleum from well sites in the Gifhorn Trough (Lower Saxony, NW-Germany) and the Maracaibo Basin (Venezuela) contained various types of microorganisms capable of degrading crude oils . Genetically related oils were inoculated with the isolated microorganisms and the degradation of the oils was followed by chromatographic techniques . Parameters important for the reactions (pH, supply of oxygen, nitrogen and phosphorus, reaction medium) were monitored and optimized . The degradation of n-alkanes was followed closely . Microorganisms active in degradation (yeast, bacteria) easily survived a period of inactivity due to missing nutrients and were reactivated within hours to degrade newly added crude oil . Under substrate-limiting conditions selectivity of degradation was found, destroying medium-chain n-alkanes (C20, C21) at a faster rate than long-chain n-alkanes (C30, C31) . During degradation the physical parameters of the crude oils (e.g . density, viscosity, average molecular weight) were altered and shifted into the direction of heavy oil . In vitro degraded oil is very similar to oil degraded in nature . Aromatic hydrocarbons and biomarker molecules (steranes and triterpanes) were not degraded under the conditions used . Pyrolysis-GC analysis of asphaltenes revealed no significant changes in the composition of pyrolyzates during biodegradation . There is sufficient evidence that heavy oils - besides some other effects - are generated by the in situ-biodegradation of conventional oils. Biopolymers, 1989 Jan, 28(1), 109 - 22 Pseudopeptides and beta folding: x-ray structures compared with structures in solution; Aubry A et al.; In order to restrain the flexibility of the peptide molecules and reduce their biodegradation, modifications of the main chain are now introduced in pseudopeptide analogues . Surprisingly, there is very little data on the conformational properties of these derivatives . We have examined pseudopeptide analogues of RCO-X-Y-NHR' model dipeptides in the depsi, N-methylated, reduced, retro, alpha, beta-dehydro, beta-amino acid, and hydrazino series, in the solid state by x-ray diffraction, and in solution by ir and 1H-nmr spectroscopy . This study provides us with accurate dimensions of the peptide surrogates, and gives some information on the conformational tendencies induced by these substitutions, with reference to those of the related dipeptide sequences. Appl Environ Microbiol, 1989 Jan, 55(1), 154 - 8 Biodegradation of polycyclic hydrocarbons by Phanerochaete chrysosporium; Bumpus JA; The ability of the white rot fungus Phanerochaete chrysosporium to degrade polycyclic aromatic hydrocarbons (PAHs) that are present in anthracene oil (a distillation product obtained from coal tar) was demonstrated . Analysis by capillary gas chromatography and high-performance liquid chromatography showed that at least 22 PAHs, including all of the most abundant PAH components present in anthracene oil, underwent 70 to 100% disappearance during 27 days of incubation with nutrient nitrogen-limited cultures of this fungus . Because phenanthrene is the most abundant PAH present in anthracene oil, this PAH was selected for further study . In experiments in which {14C}phenanthrene was incubated with cultures of P . chrysosporium containing anthracene oil for 27 days, it was shown that 7.7% of the recovered radiolabeled carbon originally present in {14C}phenanthrene was metabolized to 14CO2 and 25.2% was recovered from the aqueous fraction, while 56.1 and 11.0% were recovered from the methylene chloride and particulate fractions, respectively . High-performance liquid chromatography of the 14C-labeled material present in the methylene chloride fraction revealed that most (91.9%) of this material was composed of polar metabolites of {14C}phenanthrene . These results suggest that this microorganism may be useful for the decontamination of sites in the environment contaminated with PAHs. Rev Environ Contam Toxicol, 1989, 109, 1 - 87 Microbial metabolism of pesticides and structurally related compounds; MacRae IC; This chapter provides a review concerning the microbial metabolism of pesticides and substances that are either major metabolites from pesticides or have structural similarity to certain pesticides, and covers the period 1981 to 1987 . While reference has only been made to work published during this period, it should be realized that in some instances the results cited may confirm or expand upon earlier findings rather than being entirely novel . Therefore, the reader is referred to earlier reviews . The metabolism of pesticides in natural environments, water and wastewater, mixed microbial cultures, and pure cultures has been discussed . Attention has been drawn to the meager amount of information concerning the biodegradation of pesticides in anaerobic and marine environments . Issues such as the importance of cometabolism of pesticides in natural environments and a clear understanding of enhanced degradation of pesticides in soil still remain unresolved . Separate sections have been devoted to methodology in biodegradation studies, bound residues and removal of pesticides from soil and water . While pure culture studies have an important place in investigations into microbial metabolism of pesticides, increasing emphasis has been placed on the use of microbial consortia, either natural or artificial and microcosms to provide an understanding of pesticide biodegradation in natural environments . Another dimension in bound residue formation, one of physical entrapment in humic materials has been described . Various questions regarding the bioavailability of bound residues and whether they pose an environmental problem have not been answered fully . The microbiological removal of pesticides from soil and water by selected or genetically-engineered strains is discussed . It has been emphasized that the future success of such methods for the decontamination of soil and water depends very heavily on an improved knowledge of microbial ecology. Dev Ophthalmol, 1989, 18, 1 - 6 Novel technology in microsurgery; Parel JM; Several of the latest technical advances in microsurgical technology employing conventional engineering are briefly summarized . New scientific fields are introduced: injectable soft polymeric gels for cataract implants and vitreous substitution, controlled drug release and temporary tissue fixation via polymeric biodegradation, photodynamic therapy via intraoperative use of photosensitizers and surgical photoablation via short pulsed laser surgical instrumentation . Clinical examples covering the anterior and posterior segment of the eye are described . The potential uses of these technologies involve procedures for cataract, vitrectomy, strabismus, glaucoma and keratoplasty as well as therapeutics. Arch Microbiol, 1989, 151(5), 466 - 8 Regulation of lysine decarboxylase activity in Escherichia coli K-12; Auger EA et al.; The biodegradative lysine decarboxylase of E . coli has been reported to attain a higher specific activity when grown to saturation in the presence of excess lysine under conditions of low pH and absence of aeration . In order to examine possible sources of the pH and anaerobic regulation, a series of isogenic strains of E . coli K-12 were constructed . The effects of cadR-, fnr-, cya-, crp- and pgi- mutations on lysine decarboxylase expression were examined . Cultures were grown in a lysine supplemented rich medium at pH 5.5, pH 6.8, and pH 8.0 with and without aeration and the enzyme was assayed from log phase cultures . The results suggested that the pH and air responses were independent and that these known regulatory processes are not responsible for this regulation of the biodegradative lysine decarboxylase. Schriftenr Ver Wasser Boden Lufthyg, 1989, 80, 273 - 92 Comparison of effective toxicant biotransformation by autochthonous microorganisms and commercially available cultures in the in situ reclamation of abandoned industrial sites; Portier R et al.; Biotransformation and biodegradation of polycyclic aromatic hydrocarbons by the subsurface autochthonous microflora collected from an abandoned petroleum refinery site was investigated . In addition, the inoculation of a commercially available blend of bacterial cultures, with known ability to degrade polycyclic aromatics, was evaluated . This supplemental addition of select microorganisms has been referred to by commercial interests as "bioaugmentation" . Their biodegradative potential was evaluated using laboratory mesocosms (simulations) containing a predetermined optimal waste loading rate based on % oil and grease, mixed with predetermined optimal loading rates of clay and river silt materials . The waste consisted primarily of aliphatic and aromatic hydrocarbons found in buried sludges and abandoned lagoons . All mesocosms received nutrient amendment without additional energy sources . Experimental mesocosms were inoculated with adapted indigenous microflora and/or commercial strains . Microbial ATP, microbial diversity, and related enzyme assays were used to establish the detoxification efficiency of the experimental microflora . Quantitative toxicant concentrations and transformations were documented by GC/MS data . Information will be presented mainly on the kinetics of toxicant biotransformation processes to identify "bioaugmentation" contribution and relevancy in the recovery of abandoned polluted sites. Crit Rev Biotechnol, 1989, 8(4), 305 - 33 Hydrocarbon degradation in soils and methods for soil biotreatment; Morgan P et al.; The cleanup of soils and groundwater contaminated with hydrocarbons is of particular importance in minimizing the environmental impact of petroleum and petroleum products and in preventing contamination of potable water supplies . Consequently, there is a growing industry involved in the treatment of contaminated topsoils, subsoils, and groundwater . The biotreatment methodologies employed for decontamination are designed to enhance in situ degradation by the supply of oxygen, inorganic nutrients, and/or microbial inocula to the contaminated zone . This review considers the fate and effects of hydrocarbon contaminants in terrestrial environments, with particular reference to the factors that limit biodegradation rates . The potential efficiencies, advantages, and disadvantages of biotreatment techniques are discussed and the future research directions necessary for process development are considered. Folia Microbiol (Praha), 1989, 34(6), 479 - 84 Evaluation of alkali treatment for biodegradation of corn cobs by Aspergillus niger; Singh A et al.; Effect of NaOH pretreatment on the biodegradation of corn cobs for the production of cellulase and protein was studied using Aspergillus niger . Delignification of cobs with NaOH remarkably increased the production of cellulase and protein . Treatment of cobs with 2% NaOH was found to be the best with respect to their susceptibility to biodegradation for maximum production of cellulose 1,4-beta-cellobiosidase, cellulase, beta-glucosidase soluble protein and crude protein; this also led to the highest protein recovery, maximum cellulose utilization and also for the maximum degradation of substrate. Scanning Microsc Suppl, 1989, 3, 285 - 94; discussion 294-5 Polyurethane support films: structure and cellular adhesion; Goodman SL et al.; It is desirable to examine the cytobiology of cell adhesion to the same materials which are contemplated for use in biomedical and biotechnological devices . It is also of fundamental interest to examine adhesion to substrates with properties which are likely to influence adhesion in controlled ways . In many of these applications the materials of choice are polyurethane elastomers due to their physical properties and resistance to biodegradation . Polyurethanes have a two phase microstructure consisting of hydrophilic hard segments and hydrophobic soft segment domains . Variations of both the chemistry and the morphology of these microdomains may be produced . It is well understood that the hydrophilic/hydrophobic nature of surfaces affects cellular adhesion and the adsorption of extracellular proteins . Since polyurethane microdomains have dimensions in the range of 10-100 nm, hence the size of proteins and cell-surface receptors, polyurethane microdomain structure could influence order at the cell-material interface . Polyurethanes may be prepared as thin films with excellent properties for use as specimen supports in High Voltage transmission Electron Microscopy (HVEM) at 1 MeV . This permits the imaging of the cytoskeleton and other internal features of whole mounts of adherent cells, rather than tedious thin sectioning required for conventional TEM . Subsequently the surface morphology of these preparations may be imaged with high resolution SEM . Finally, the polyurethane itself may be stained and imaged by either HVEM or high resolution SEM in order to relate polyurethane micro-morphology to cellular features. Epilepsia, 1989, 30 Suppl 1, S42 - 50; discussion S64-8 Designing molecules: specific peptides for specific receptors; Hruby VJ; Peptides are the largest class of mediators of intercellular communication in the central nervous system . These molecules pose special problems in design for potential medical applications because of the high degree of flexibility, lack of high receptor selectivity, and ready biodegradation or clearance . The global and local use of conformational constraints has overcome these difficulties . Structure-biological activity relationships, molecular modeling, conformational analysis, conformational calculations, and molecular dynamics simulations can all be used to derive suitable lead structures and conformational models . Often, a single, constrained peptide analogue can be designed, which will have many of the desired biological and biophysical properties, and will serve as a template . Peptide analogues with high potency, exquisite receptor selectivity, and biological stability can be obtained . The approach is illustrated by the design of cyclic enkephalin-agonist analogues with exceptional delta-opioid-receptor selectivity, and of constrained somatostatin analogues that have become opioid peptides and possess potent opioid antagonist activities and exceptional selectivity for mu-opioid receptors. J Oral Implantol, 1989, 15(1), 41 - 6 A scanning electron microscopic study of in vitro toxicity of ethylene-oxide-sterilized bone repair materials; Zislis T et al.; Polylactic acid (PLA) and polyglycolic acid (PGA) have been under investigation for use in the management of hard- and soft-tissue wounds . Current research has included the incorporation of osteo-inductive substances into a PLA-PGA copolymer alloplastic implant material for enhancement of the healing of osseous defects . Conventional methods of sterilization--such as dry heat, steam heat, or 60Co--tend either to destroy or attenuate osteo-inductive activity and alter polymer biodegradation . Ethylene oxide (EO) gas sterilization is currently being tested as an alternate method . This study examined the relationship of EO-induced cytotoxicity to the length of time of polymer aeration following EO sterilization . Three groups of copolymer implant discs were studied: (1) 50:50 PLA-PGA copolymer, (2) PLA-PGA polymer with hydroxyapatite (HA), and (3) PLA-PGA with autolyzed, antigen-extracted (AA) bone particles . Polymer discs, as well as particulate HA and AA bone controls, were sterilized with EO for 12 hours . Following periods of two weeks, one week, one day, or no subsequent vacuum aeration, samples were placed into 24-well culture plates . A suspension of human fibroblasts was added to each well . Cell growth and attachment were permitted for 24 hours . Medium was then removed, and solutions for cell fixation, buffer washing, and dehydration were added to each well . SEM examination revealed changes in cell growth with increasing periods of aeration suggestive of increasing cell vitality . Cells growing on discs having no aeration were small, round, and lobulated, whereas those of seven to 14 days' aeration were more numerous, and flattened with many microvilli, pseudopodia, and dendritic processes, features consistent with normal cell morphology . These results suggest that EO-sterilized polymer implants should be aerated for least seven to 14 days prior to surgical use. Acta Biol Hung, 1989, 40(1-2), 3 - 36 Role, mechanism of action and application of gonadoliberins in reproductive processes; Teplan I; Gonadoliberin (gonadotropin releasing hormone, GnRH) plays a central role in the regulation of reproductive functions as it regulates the release of both luteinizing hormone (LH) and follicle stimulating hormone (FSH) . The isolation and structure determination of GnRH opened the possibility of its use for influencing reproductive processes . This possibility initiated a rapid development in the design of potent and long-acting GnRH agonists and antagonists . The most important structural modifications of GnRH leading to superagonists are the D-amino acid substitutions in position 6 combined with Pro9-ethylamide or azaGly10 at the C-terminus . We have synthesized several superagonists of GnRH according to these substitution principles . Furthermore, our L-isoaspartyl modification in position 6, as a new approach to GnRH agonist design, also resulted in superactive analogs . The recently discovered sequences of non-mammalian GnRH-s opened new routes for us to synthesize species specific GnRH agonists . All three groups of the above mentioned GnRH analogs have been successfully used for the treatment of sexual disorders of different animals (cattle, pigs, rabbits, etc.) . Ovulation synchronization and a 30% increase in the fertility rate could be achieved by using GnRH agonists in cattle breeding . Analogs derived from species specific sequences could be applied for the induced artificial propagation of fish even out of the spawning season . It is known that superactive GnRH analogs can suppress the growth of certain hormone-dependent tumours . In vitro and in vivo tests of our analogs showed promising antitumour activity in breast cancer which might be explained by the mechanism of desensitization . Almost a hundred antagonist analogs of GnRH have been developed in our laboratory . The most effective ones contain 4 or 5 D-amino acids, and one of them is even orally active . The inhibition of ovulation can also be achieved by the administration of GnRH superagonists . This phenomenon might also be explained by the desensitization of LH-release . Radioactive analogs specifically labeled with tritium in different amino acid residues have been synthesized and used for studying tissue distribution and biodegradation of gonadoliberins . Analogs containing a photoreactive group have been prepared and applied for the trials of GnRH receptor isolation. Biomaterials, 1989 Jan, 10(1), 59 - 62 Macroporous calcium phosphate bioceramics in dog femora: a histological study of interface and biodegradation; Klein CP et al.; This study examines the biodegradation behaviour of calcium phosphate macroporous bioceramics consisting of hydroxylapatite or beta-whitlockite implants . The implantations were performed in hard tissue of femora and muscular tissue of dogs for periods of 6 and 12 month . With microradiography and light microscopy, respectively, of ground and thin sections it was shown that hydroxylapatite remained unchanged and beta-whitlockite degraded within 6 month in bone tissue . In the muscular tissue, the biodegradation of beta-whitlockite was slower . In addition, beta-whitlockite gave rise to a cellular response of lymphocytes and plasma cells rather than hydroxylapatite in the soft tissue region . For tissue response hydroxylapatite is more suitable as an implant material than beta-whitlockite. Biochem Biophys Res Commun, 1988 Dec 30, 157(3), 992 - 9 Manganese, Mn-dependent peroxidases, and the biodegradation of lignin; Forrester IT et al.; Manganese and Mn-dependent peroxidases have been implicated in the enzymatic degradation of lignin . However, the specific role of manganese is uncertain . We report here the novel observation that in the absence of enzyme, suitably chelated Mn3+ is a ligninolytic agent capable of oxidizing veratryl alcohol, lignin model compounds, and lignin . We also demonstrate the unexpected effect of reducing agents which stimulate the oxidations by Mn3+ . The stimulation is apparently through the production of a reduced oxygen species likely to be superoxide . These observations provide a fresh insight into the process of lignin biodegradation. Z Orthop Ihre Grenzgeb, 1988 Dec, 126(6), 688 - 92 {Is high-density polyethylene suitable as an implant material in cement-free anchoring of hip endoprostheses? A histomorphologic study of an explanted polyethylene screw-in acetabula}; Lintner F et al.; Firmly attached screw-in polyethylene acetabula which had been implanted for between 16 and 54 months were explanted after autopsies and subjected to macroscopic, radiologic and histologic examination . Metaplasias were seen around the threads and on the floor of the acetabulum . Their tendency to ossify represents an attempt at secondary stabilization . Due to the low stability of the polyethylene this causes increased wear on the floor of the acetabulum . The small defects in the polyethylene found in the threads, resembling damage done by mice, may be a sign of biodegradation . In view of the tissue reactions pointed out, the material stability of the polyethylene needs to be improved or implantation must be restricted to a very limited range of indications. Appl Environ Microbiol, 1988 Dec, 54(12), 3177 - 9 Effect of inorganic nutrients on the acclimation period preceding mineralization of organic chemicals in lake water; Jones SH et al.; The addition of phosphate, nitrate, or sulfate (each at 10 mM) decreased the acclimation period for the mineralization of low concentrations of p-nitrophenol (PNP) in lake water . Added phosphate shortened the acclimation period for biodegradation of 2 ng to 2 micrograms of PNP per ml in various lake water samples and of 2,4-dichlorophenoxyacetate at 100 ng/ml . Added P enhanced the rate of growth of PNP-mineralizing microorganisms in waters containing 200 ng or 2 micrograms of PNP per ml . We suggest that the effect of P on the acclimation period results from an increase in the growth rate of the initially small population of microorganisms able to mineralize the synthetic chemicals. Appl Environ Microbiol, 1988 Dec, 54(12), 3034 - 8 Three dehalogenases and physiological restraints in the biodegradation of haloalkanes by Arthrobacter sp . strain HA1; Scholtz R et al.; Arthrobacter sp . strain HA1 utilizes 18 C2-to-C8 1-haloalkanes for growth and synthesizes an inducible 1-bromoalkane debrominase of unknown physiological function (R . Scholtz, T . Leisinger, F . Suter, and A.M . Cook, J . Bacteriol . 169:5016-5021, 1987) in addition to an inducible 1-chlorohexane halidohydrolase which dehalogenates some 50 substrates, including alpha, omega-dihaloalkanes . alpha, omega-Dihaloalkanes were utilized by cultures of strain HA1 under certain conditions only . C9 and C8 homologs prevented growth . At suitable concentrations, C7-to-C5 homologs could serve as sole sources of carbon and energy for growth . C4 and C3 homologs could be utilized only in the presence of a second substrate (e.g., butanol), and the C2 homolog was not degraded . Kinetics of growth and substrate utilization indicated that cells of strain HA1 growing in butanol-salts medium could be used to test whether compounds induced the 1-chlorohexane halidohydrolase . No gratuitous induction of synthesis of the enzyme was observed . Many enzyme substrates (e.g., bromobenzene) did not induce synthesis of the enzyme, though the enzyme sequence to degrade the product (phenol) was present . Some inducers (e.g., bromomethane) were enzyme substrates but not growth substrates . In an attempt to find a physiological role for the 1-bromoalkane debrominase, we observed that several long-chain haloaliphatic compounds (greater than C9; e.g., 1-bromohexadecane and 1-chlorohexadecane) were utilized for growth and that induced cells could dehalogenate several 1-haloalkanes (at least C4 to C16) . The dehalogenation of the long-chain compounds could not be assayed in the cell extract, so we presume that a third haloalkane dehalogenase was present.(ABSTRACT TRUNCATED AT 250 WORDS) Appl Environ Microbiol, 1988 Dec, 54(12), 2976 - 80 Dependence of tetrachloroethylene dechlorination on methanogenic substrate consumption by Methanosarcina sp . strain DCM; Fathepure BZ et al.; Tetrachloroethylene (perchloroethylene, PCE) is a suspected carcinogen and a common groundwater contaminant . Although PCE is highly resistant to aerobic biodegradation, it is subject to reductive dechlorination reactions in a variety of anaerobic habitats . The data presented here clearly establish that axenic cultures of Methanosarcina sp . strain DCM dechlorinate PCE to trichloroethylene and that this is a biological reaction . Growth on methanol, acetate, methylamine, and trimethylamine resulted in PCE dechlorination . The reductive dechlorination of PCE occurred only during methanogenesis, and no dechlorination was noted when CH4 production ceased . There was a clear dependence of the extent of PCE dechlorination on the amount of methanogenic substrate (methanol) consumed . The amount of trichloroethylene formed per millimole of CH4 formed remained essentially constant for a 20-fold range of methanol concentrations and for growth on acetate, methylamine, and trimethylamine . These results suggest that the reducing equivalents for PCE dechlorination are derived from CH4 biosynthesis and that the extent of chloroethylene dechlorination can be enhanced by stimulating methanogenesis . It is proposed that electrons transferred during methanogenesis are diverted to PCE by a reduced electron carrier involved in methane formation. Appl Environ Microbiol, 1988 Dec, 54(12), 2885 - 9 Biodegradation of pentachlorophenol by the white rot fungus Phanerochaete chrysosporium; Mileski GJ et al.; Extensive biodegradation of pentachlorophenol (PCP) by the white rot fungus Phanerochaete chrysosporium was demonstrated by the disappearance and mineralization of {14C}PCP in nutrient nitrogen-limited culture . Mass balance analyses demonstrated the formation of water-soluble metabolites of {14C}PCP during degradation . Involvement of the lignin-degrading system of this fungus was suggested by the fact the time of onset, time course, and eventual decline in the rate of PCP mineralization were similar to those observed for {14C}lignin degradation . Also, a purified ligninase was shown to be able to catalyze the initial oxidation of PCP . Although biodegradation of PCP was decreased in nutrient nitrogen-sufficient (i.e., nonligninolytic) cultures of P . chrysosporium, substantial biodegradation of PCP did occur, suggesting that in addition to the lignin-degrading system, another degradation system may also be responsible for some of the PCP degradation observed . Toxicity studies showed that PCP concentrations above 4 mg/liter (15 microM) prevented growth when fungal cultures were initiated by inoculation with spores . The lethal effects of PCP could, however, be circumvented by allowing the fungus to establish a mycelial mat before adding PCP . With this procedure, the fungus was able to grow and mineralize {14C}PCP at concentrations as high as 500 mg/liter (1.9 mM). Int J Oral Maxillofac Surg, 1988 Dec, 17(6), 354 - 7 The hydroxylapatite-bone interface . Studies on a human biopsy; Blijdorp PA et al.; Augmentation of the mandible with HA and cancellous bone appears to be a clinically stable and reliable procedure . A human biopsy, taken after 16 months, shows a mature bone frame embedding HA particles and a stable HA-bone interface . Minimal biodegradation was observed in the subperiosteal layer. J Card Surg, 1988 Dec, 3(4), 523 - 33 The cross-linking and structure modification of the collagen matrix in the design of cardiovascular prosthesis; Nimni ME; Glutaraldehyde cross-linking of native or reconstituted collagen fibrils and tissues rich in collagen significantly reduces biodegradation . Other aldehydes are less efficient than glutaraldehyde in generating chemically, biologically, and thermally stable cross-links . Implants of collagenous materials cross-linked with glutaraldehyde are subject long-term to calcification, biodegradation, and low-grade immune reactions . We have attempted to overcome these problems by enhancing cross-linking through (a) bridging of activated carboxyl groups with diamines and (b) using glutaraldehyde to cross-link the epsilon-NH2 groups in collagen and the unreacted amines introduced by aliphatic dismines . This cross-linking reduces tissue degradation and nearly eliminates humoral antibody induction . Covalent binding of diphosphonates, specifically 3-amino-1-hydroxypopane-1, 1-diphosphonic acid (3-APD), and to a lesser extent chondroitin sulfate to collagen or to the cross-ling-enhanced collagen network reduces its potential for calcification . Platelet aggregation also is reduced by glutaraldehyde cross-linking and nearly eliminated by the covalent binding of chondroitin sulfate to collagen . The cytotoxicity of residual glutaraldehyde can be minimized by chemical neutralization and thorough rough rinsing. Eur J Biochem, 1988 Nov 15, 177(3), 569 - 74 Photoaffinity labeling of the allosteric AMP site of biodegradative threonine dehydratase of Escherichia coli with 8-azido-AMP; Patil RV et al.; The photoreactive AMP analog, 8-azido-AMP, stimulated the activity of biodegradative threonine dehydratase of Escherichia coli in a reversible manner and, like AMP, decreased the Km for threonine . The concentrations required for half-maximal stimulation by AMP and 8-azido-AMP were 40 microM and 1.5 microM, respectively, and the maximum stimulation by 8-azido-AMP was 25% of that seen with AMP . Gel-filtration experiments revealed that 8-azido-AMP stabilized a dimeric form of the enzyme, whereas AMP promoted a tetrameric species . When present together, AMP and 8-azido-AMP showed mutual competition in influencing catalytic activity as well as the conformational state of the protein . Photolabeling of AMP-free dehydratase with 8-azido-{2-3H}AMP resulted in a time and concentration-dependent enzyme inactivation and concomitant incorporation of 8-azido-AMP into protein . At low 8-azido-AMP concentrations, incorporation of about 1 mol 8-azido-AMP/mol dehydratase tetramer was correlated with almost complete inactivation of the enzyme . The presence of AMP in the photolabeling reaction greatly reduced the extent of enzyme inactivation and 8-azido-AMP binding . Ultraviolet irradiation with 20 microM 3H-labeled 8-azido-AMP revealed one tryptic peptide, Thr230-Thr-Gly-Thr-Leu-Ala-Asp-Gly-Cys-Asp-Val-Ser-Arg242, with bound radioactivity . This peptide, labeled at low concentration of 8-azido-AMP, most likely represents the AMP-binding region on the dehydratase molecule. Appl Environ Microbiol, 1988 Nov, 54(11), 2803 - 7 Role of chemical concentration and second carbon sources in acclimation of microbial communities for biodegradation; Wiggins BA et al.; A study was conducted to determine the role of concentration of the test chemical, of a second organic compound, and of mutation in the acclimation period before the mineralization of organic compounds in sewage . The acclimation period for the mineralization in sewage of 2 micrograms of 4-nitrophenol (PNP) per liter increased from 6 to 12 days in the presence of 10 mg of 2,4-dinitrophenol per liter . The extension of the acclimation period was equivalent to the time required for mineralization of 2,4-dinitrophenol . In contrast, the time for acclimation for the degradation of 2 micrograms of PNP per liter was reduced when 10 or 100 mg of phenol per liter was added . Lower phenol levels increased the acclimation period to 8 days . The length of the acclimation period for PNP mineralization decreased as the initial concentration of PNP increased from 2 micrograms to 100 mg/liter . The acclimation period for phenol mineralization was lengthened as the phenol concentration increased from 100 to 1,400 mg/liter . The length of the acclimation period for PNP and phenol biodegradation was reproducible, but it varied among replicates for the biodegradation of other nitro-substituted compounds added to sewage or lake water, suggesting that a mutation was responsible for acclimation to these other compounds . The acclimation period may thus reflect the time required for the destruction of toxins, and it also may be affected by the concentration of the test compound or the presence of other substrates. J Bacteriol, 1988 Nov, 170(11), 5360 - 3 Genetic analysis of the tdcABC operon of Escherichia coli K-12; Schweizer HP et al.; The biodegradative threonine dehydratase (tdc) operon was mapped at 68 min on the Escherichia coli K-12 chromosome . The order of markers in the clockwise direction was dnaG uxaA tdc argG . A tdc deletion was isolated and mapped to this region of the chromosome . By using a tdcB-lacZ fusion the clockwise direction of transcription of tdc was determined. J Bacteriol, 1988 Nov, 170(11), 5352 - 9 Molecular characterization of the tdc operon of Escherichia coli K-12; Goss TJ et al.; The nucleotide sequence of a 2-kilobase DNA fragment of the tdc region of Escherichia coli K-12, previously cloned in this laboratory, revealed two open reading frames, tdcC and ORFX, downstream from the tdcB gene (formerly designated tdc) encoding biodegradative threonine dehydratase . A 24-base-pair sequence separated tdcC from the dehydratase coding region, and an untranslated region of 60 nucleotides, which contains a recognizable -10 consensus sequence, was found between tdcC and ORFX . The deduced amino acid sequence of tdcC showed it to be a large hydrophobic polypeptide of 431 amino acid residues, whereas ORFX coded for a small 135-residue polypeptide lacking glutamine and tryptophan . A computer-assisted sequence analysis revealed no similarity among the tdcB, tdcC, and ORFX polypeptides, and a search of the GenBank database failed to detect similarity with any other known proteins . The tdc genes and ORFX showed similar codon usage and, in analogy with other bacterial genes, showed codon usage typical for genes expressed at an intermediate level . Transcriptional analysis with S1 nuclease indicated two distinct transcription start sites upstream of the tdcB gene in regions previously identified as promoterlike elements P1 and P2 . Interestingly, expression of tdcB and tdcC, but not ORFX, was contingent upon the presence of P1 . These results taken together tend to suggest that the biodegradative threonine dehydratase is the second gene in a polycistronic transcription unit constituting a novel operon (tdcABC) in E . coli implicated in anaerobic threonine metabolism. Biochem J, 1988 Oct 15, 255(2), 483 - 91 Kinetic lability of zinc bound to metallothionein in Ehrlich cells; Krezoski SK et al.; Ehrlich ascites-tumour cells normally contain a large concentration of Zn-metallothionein . When cells are placed in culture media, containing or pretreated with the metal-ion-chelating resin Chelex-100, they stop growing, remain viable and lose zinc specifically from the metallothionein (MT) pool . The kinetics of loss of zinc are first-order and are very rapid, having a rate constant of greater than or equal to 0.6 h-1 . MT protein labelled with 35S is biodegraded with a rate constant of 0.07-0.014 h-1 in control cells, 0.08 h-1 in cells exposed to the zinc-deficient medium and 0.12-0.18 h-1 in cells treated directly with Chelex . Over the 6 h period in which zinc is totally lost from Zn-MT there is relatively little decrease in MT-like protein as measured by cadmium-binding to the 10,000-Mr protein fraction . Other pools of zinc and 35S-labelled protein turn over more slowly . There is no loss of zinc from rat liver Zn-MT that is dialysed against Chelex to model the possible reaction of the resin with Ehrlich-cell Zn-MT . However, Chelex does compete slowly for MT-bound zinc when resin and MT are directly mixed . Analysis of the known and possible pathways of zinc metabolism in cells in relationship to these rate constants shows that biodegradation of MT protein cannot account for the rate of loss of zinc from Zn-MT. Biochem J, 1988 Oct 15, 255(2), 445 - 50 Veratryl alcohol oxidases from the lignin-degrading basidiomycete Pleurotus sajor-caju; Bourbonnais R et al.; The basidiomycete Pleurotus sajor-caju mineralizes ring-14C-labelled lignin (dehydrogenative polymer) when grown in mycological broth . Under these conditions, two veratryl alcohol oxidase (VAO) enzymes were found in the culture medium . They oxidized a number of aromatic alcohols to aldehydes and reduced O2 to H2O2 . The enzymes were purified by ion-exchange and gel-permeation chromatography . The final step of purification on Mono Q resolved the activity into two peaks (VAO I and VAO II) . Both enzymes had the same Mr, approx . 71,000, but their isoelectric points differed slightly, 3.8 for VAO I and 4.0 for VAO II . Their amino acid compositions were similar except for aspartic acid/asparagine and glycine . Both enzymes are glycoproteins and contain flavin prosthetic groups . Their pH optima were around 5, and kinetic constants and specificities were similar . 4-Methoxybenzyl alcohol was oxidized the most rapidly, followed by veratryl alcohol . Not all aromatic alcohols were oxidized, neither were non-aromatic alcohols . Cinnamyl alcohol was oxidized at the gamma position . The VAO enzymes thus represent a significantly different route for veratryl alcohol oxidation from that catalysed by the previously found lignin peroxidases from Phanerochaete chrysosporium . The role of the oxidases in biodegradation might be to produce H2O2 during oxidation of lignin fragments. J Biomater Appl, 1988 Oct, 3(2), 260 - 96 The use of silicone/polyurethane graft polymers as a means of eliminating surface cracking of polyurethane prostheses; Pinchuk L et al.; The long-term biodegradation of various polyurethanes with and without surface modifications was evaluated by implanting small porous filamentous patches of these materials subcutaneously in the backs of dogs for one month . Data were compared to those obtained with spun polyurethane vascular grafts of similar materials implanted in the aorto-iliac position in dogs . The extremely high surface area of approximately 7 m2/cm3 of these porous filamentous patches provided numerous sites for surface cracking and the very fine filaments (10 microns in diameter) provided an easily identifiable structure to study the cracking phenomenon . Results from numerous one month implants clearly demonstrated that the subcutaneous implant model effectively reproduced the biodegradation behavior observed in vascular graft implants . The degradation was most pronounced in the softer Shore 80A polyurethanes and less pronounced in the harder 55D and 75D polyurethanes . The degradation could not simply be stopped by stress annealing the polyurethane and the degradation did not require the presence of metallic ions . Antioxidants, surface adsorbed albumin, poly(2-hydroxyethyl-methacrylate) grafting, silicone copolymerization, tetrafluoroethylene plasma discharge and the addition of urea linkages to the polymer were also shown to be ineffective in stopping the biodegradation process . In contrast, covalent bonding or grafting of silicone polymer to the surface of the urethane successfully inhibited the biodegradation process. Ecotoxicol Environ Saf, 1988 Oct, 16(2), 95 - 105 Anaerobic biodegradation of polychlorinated biphenyls by bacteria from Hudson River sediments; Chen M et al.; Anaerobic biodegradation of monochlorobiphenyls; a tetrachlorobiphenyl; Aroclor 1221, a polychlorinated biphenyl (PCB) mixture; and sediment PCBs was investigated by using mixed bacterial populations from Hudson River sediments obtained by PCB enrichment . When the bacteria were incubated with Aroclor 1221, the disappearance of congeners was in general inversely related to GC retention time and thus indirectly to the octanol/water partition coefficient . When incubated with 14C-labeled monochlorobiphenyls, 14CO2 was detected, but methane was not . Radioactivity was also found in the cell material and the aqueous fraction . 2,4,2',4'-Tetrachlorobiphenyl produced little evidence of biodegradation or reductive dechlorination . Inoculation of anaerobic sediments from the Hudson River with the mixed population produced a marked decrease in sediment PCBs, whereas uninoculated sediments were observed to have little change . This decrease was also related to the partition coefficient. Biomaterials, 1988 Sep, 9(5), 463 - 5 Sudan black B as a histological stain for polymeric biomaterials embedded in glycol methacrylate; Hoeksma EA et al.; Sudan black B, usually a stain for all kinds of lipid, turned out to be an excellent histological stain for polymeric biomaterials embedded in glycol methacrylate . Staining the surrounding connective tissue with toluidine blue-basic fuchsin makes details of the polymer-tissue interface clearly visible . Sudan black B might be used to visualize the biodegradation process of polymeric biomaterials. Vopr Med Khim, 1988 Sep-Oct, 34(5), 91 - 3 {Inhibition of cytochrome P-450-dependent enzymes in rat liver microsomes by tetraphenylporphyrin and its metal complexes}; Galkin BN et al.; Tetraphenyl porphyrin (TPP) and its complexes with Fe3+, Co2+, Cu2+, Zn2+ and Ni2+ inhibited cytochrome P-450-dependent enzymes in rat liver microsomes . Content of cytochrome P-450 was decreased by 27% or 49% depending on the substance administered (TPP or its metal complexes, respectively) . N-demethylase was inactivated by about 30%; the rate of aniline p-hydroxylation was decreased by 30-45% depending on the type of the metal complex . But these substances did not affect practically the benz(alpha)pyrene hydroxylase activity . The inhibitory effect of TPP of its metal complexes appears to occur due to activation of lipid peroxidation and of hemoxygenase, which is responsible for biodegradation of hem in cytochrome P-450. J Cardiovasc Pharmacol, 1988 Sep, 12(3), 293 - 9 Salutary effects of CG-4203, a novel, stable prostacyclin analog, in hemorrhagic shock; Bitterman H et al.; Prostacyclin (PGI2) is a potent vasodilator, an inhibitor of platelet aggregation, and a membrane-stabilizing agent that has been shown to exert beneficial effects in a variety of models of ischemia and circulatory shock . However, the use of PGI2 is limited by its instability and rapid biodegradation . We studied the effects of a novel, stable prostacyclin analog, CG-4203, in a murine model of hemorrhagic shock . Hemorrhaged rats treated with CG-4203 maintained postreinfusion mean arterial blood pressure (MABP) at significantly higher values than rats receiving only the vehicle (final MABP 101 +/- 3 vs . 75 +/- 5 mm Hg, p less than 0.01) . CG-4203 was also found to attenuate the increase in plasma cathepsin D activity (p less than 0.01), as well as the plasma accumulation of free amino-nitrogen compounds (p less than 0.05) . Furthermore, the plasma activity of a myocardial depressant factor (MDF) was significantly lower in CG-4203-treated hemorrhaged rats than in rats receiving the vehicle (25 +/- 2 vs . 54 +/- 7 U/ml, p less than 0.01) . In addition, CG-4203 exerted an anti-proteolytic action in pancreatic homogenates and inhibited platelet aggregation in platelet-rich plasma . However, CG-4203, at concentrations expected during treatment of shock, failed to have an immediate or delayed vasodilator effect in rat aortic rings, and thus vasodilation is not an important aspect of the antishock effects of CG-4203 . Our results suggest that inhibition of platelet aggregation, as well as the antiproteolytic and membrane-stabilizing actions, could mediate the beneficial effects of CG-4203 in hemorrhagic shock. FEBS Lett, 1988 Jul 18, 234(2), 331 - 5 Primary structure of rat liver serine dehydratase deduced from the cDNA sequence; Noda C et al.; The nucleotide sequence of serine dehydratase mRNA of rat liver has been determined from a recombinant cDNA clone, previously cloned in this laboratory, and from a recombinant cDNA clone screened from a primer-extended cDNA library . The sequence of 1322 nucleotides includes the entire protein coding region and noncoding regions on the 3'- and 5'-sides . The deduced polypeptide consists of 327 amino acid residues with a calculated molecular mass of 34,462 Da . Comparison of the amino acid sequences of the serine dehydratase polypeptide with those of biosynthetic threonine dehydratase of yeast and biodegradative threonine dehydratase of E . coli revealed various extents of homology . A heptapeptide sequence, Gly-Ser-Phe-Lys-Ile-Arg-Gly, which is the pyridoxal-binding site in the yeast and E . coli threonine dehydratases was found as a highly conserved sequence. Appl Environ Microbiol, 1988 Jul, 54(7), 1724 - 30 Photolysis primes biodegradation of benzo{a}pyrene; Miller RM et al.; 14C-labeled benzo{a}pyrene (BaP) was used as a model-compound for polycyclic aromatic hydrocarbons (PAH) in order to assess the effect of photolytic pretreatment on the subsequent fate of BaP in sewage sludge and soil test systems . Photolysis was performed in methanolic solution with or without 0.1 M H2O2, under either UV light (300 nm) or natural sunlight . The presence of H2O2 greatly enhanced the rate of photolysis both with UV and with natural sunlight . Intact BaP resisted biodegradation in both test systems . Photolysis transformed BaP to polar materials that were subject to increased mineralization and binding in both biological test systems . As shown by the Ames assay, photolysis decreased the mutagenicity of BaP to test strains TA98 and TA104 only moderately . The photolysate had an increased acute toxicity and lost its need for activation by S-9 enzymes . However, during subsequent incubation in soil or sewage sludge, mutagenicity decreased rapidly by one to two orders of magnitude and acute toxicity disappeared due to the mineralization and binding of photoproducts to humic materials . Photolysis of BaP and similar PAH compounds represents a useful treatment option that could be applied to certain PAH-containing petroleum refinery sludge and to coal tar residues in order to facilitate their detoxification and environmentally safe disposal. ASAIO Trans, 1988 Jul-Sep, 34(3), 839 - 44 A tricuspid polyurethane heart valve as an alternative to mechanical prostheses or bioprostheses; Lo HB et al.; The main disadvantages of today's heart valve prostheses are the need for lifelong anticoagulation for mechanical valves and problems with biodegradation for tissue valves . Therefore, a new valve type devoid of these problems would be a major step forward . In order to evaluate a new valve design made by dipmolding with different PU materials, an animal test series was carried out in which two valves from each material were implanted into the mitral position of growing Jersey calves . The surgical procedure and postoperative catheterization data are presented . The survival times ranged between 127 and 291 days . Organs and explanted valves were examined post mortem according to general pathology standards . Specifically, the valves were histologically examined for calcium deposits and investigated by light microscopy, REM and EDAX . All explanted valves showed calcification and immobilization, but the results suggest that at least two PU materials attain survival times which are far beyond the lifetime of bioprostheses under the same implant conditions, justifying further in vivo studies in adult animals. J Biomed Mater Res, 1988 Jun, 22(6), 509 - 27 Analysis of in vitro enzymatic and oxidative degradation of polyurethanes; Ratner BD et al.; In vitro biodegradation studies were performed to assess the long-term stability of poly(ether urethane) (PEU) implants . Three PEU's and one poly(ester urethane) were treated with enzymes characteristic of those released from inflammatory cells during the foreign body reaction . In addition, the effect of hydrogen peroxide was observed to examine oxidative degradation . Polymers were prepared as thin films on glass, gold, silver, and copper substrates to test the possibility of metal-catalyzed degradation . Molecular weights and polydispersities of the polymers were measured by gel permeation chromatography (GPC) before and after treatment . Changes in peak shape and location were also monitored . The results demonstrate that varying degrees of both enzymatic and oxidative degradation occurred. Microbiol Sci, 1988 Jun, 5(6), 165 - 9 Adaptation of aquatic microbial communities to pollutant stress; Barkay T et al.; The importance of microbial adaptation in the removal of environmental pollutants and in maintaining active microbial communities in impacted ecosystems is discussed using the biodegradation of p-nitrophenol and the volatilization of mercuric mercury as examples . A molecular mechanism of adaptation is suggested by enrichment of mercury resistance (mer) genes in some communities upon exposure to mercury. Appl Environ Microbiol, 1988 May, 54(5), 1277 - 9 Effects of some alkyl phenols on methanogenic degradation of phenol; Wang YT et al.; The effects of six phenolic compounds (o-, m-, and p-cresol and 2-, 3-, and 4-ethylphenol) on the anaerobic biodegradation of phenol was examined in batch methanogenic cultures . Results showed that ethylphenols were more inhibitory of phenol degradation than were cresols . The inhibitory effects of the three isomers of cresol and ethylphenol did not vary with the isomer but rather with the substituted functional group. Appl Environ Microbiol, 1988 May, 54(5), 1243 - 8 Microbial degradation of n-alkyl tetrahydrothiophenes found in petroleum; Fedorak PM et al.; Although n-alkyl-substituted tetrahydrothiophenes are found in nonbiodegraded petroleums, they are not found in petroleums which have undergone biodegradation in their reservoirs . These observations suggested that this group of compounds with alkyl chain lengths from approximately C10 to at least C30 is biodegradable . Two of these sulfides, 2-n-dodecyltetrahydrothiophene (DTHT) and 2-n-undecyltetrahydrothiophene, were synthesized, and their biodegradabilities were tested by using five gram-positive, n-alkane-degrading bacterial isolates . The alkyl side chains of these compounds were oxidized, and the major intermediates found in 2-n-undecyltetrahydrothiophene- and DTHT-metabolizing cultures were 2-tetrahydrothiophenecarboxylic acid (THTC) and 2-tetrahydrothiopheneacetic acid (THTA), respectively . Four n-alkane-degrading fungi were also shown to degrade DTHT, yielding both THTA and THTC . Quantitation of tetrahydrothiophene ring-containing products in 28-day-old bacterial and fungal cultures suggested that THTC and THTA were metabolized further to unidentified products . In addition, two of the bacterial isolates were shown to degrade a mixture of n-alkyl tetrahydrothiophenes isolated from Bellshill Lake crude oil. Appl Environ Microbiol, 1988 May, 54(5), 1143 - 50 Biodegradation of crystal violet by the white rot fungus Phanerochaete chrysosporium; Bumpus JA et al.; Biodegradation of crystal violet (N,N,N',N',N'',N''-hexamethylpararosaniline) in ligninolytic (nitrogen-limited) cultures of the white rot fungus Phanerochaete chrysosporium was demonstrated by the disappearance of crystal violet and by the identification of three metabolites (N,N,N',N',N''-pentamethylpararosaniline, N,N,N',N''-tetramethylpararosaniline, and N,N',N''-trimethylpararosaniline) formed by sequential N-demethylation of the parent compound . Metabolite formation also occurred when crystal violet was incubated with the extracellular fluid obtained from ligninolytic cultures of this fungus, provided that an H2O2-generating system was supplied . This, as well as the fact that a purified ligninase catalyzed N-demethylation of crystal violet, demonstrated that biodegradation of crystal violet by this fungus is dependent, at least in part, upon its lignin-degrading system . In addition to crystal violet, six other triphenylmethane dyes (pararosaniline, cresol red, bromphenol blue, ethyl violet, malachite green, and brilliant green) were shown to be degraded by the lignin-degrading system of this fungus . An unexpected result was the finding that substantial degradation of crystal violet also occurred in nonligninolytic (nitrogen-sufficient) cultures of P . chrysosporium, suggesting that in addition to the lignin-degrading system, another mechanism exists in this fungus which is also able to degrade crystal violet. Microbiol Sci, 1988 May, 5(5), 132 - 6 Use of microcosms to study genetic interactions between microorganisms; Trevors JT; Microcosms are used regularly in the study of the toxicity of environmental chemicals and their biodegradation . The use of these systems to study genetic interactions and adaptation mechanisms in soil and aquatic microorganisms is discussed, and their application to studies on the fate of genetically engineered organisms and their genes in the natural environment is outlined. Kosm Biol Aviakosm Med, 1988 May-Jun, 22(3), 67 - 71 {Products of microbiological biodegradation of polymer materials as a factor of possible contamination of the atmosphere of hermetically sealed compartments with toxic substances}; Nefedov IuG et al.; The purpose of the present investigation was to determine hygienic relevance of microbial degradation of polymers in an enclosed environment . Experiments were carried out to study the growth and development of microorganisms--molds and bacteria--on polymers . It was found that the process may be accompanied by the formation of volatile toxic substances, i.e . biodegradation products resulting from microbial decomposition of polymer components . Polymer ingredients are the major factor that determines the qualitative and quantitative composition of volatile substances . The accumulation of these substances on polymers leads to the deterioration of their sanitary-chemical properties and consequently to the contamination of the environment . It is shown that the basic products of biodegradation of polyurethane foam are ethanol and acetaldehyde and those of polyvinyl chloride plates, isooctanol (2-ethyl hexanol) . The environmental parameters affect the microbial activity and therefore the rate of biodegradation processes. Regul Toxicol Pharmacol, 1988 Mar, 8(1), 4 - 21 Environmental risk assessment of surfactants: fate and environmental effects in Lake Biwa basin; Sueishi T et al.; Environmental risk incurred with the use of synthetic surfactants is dealt with in this paper . The background and necessity of risk management related to surfactant usage in the Lake Biwa basin are introduced, as well as a research scheme that acknowledges risks in three sub-processes--consumption and discharge, fate in aquatic environment, and ecotoxicological response of linear alkylbenzene sulfonate (LAS) . The ayu (Plecoglossus altivelis) has been selected as the significant biological target in the basin . Results of a field survey of the behavior of LAS along streams flowing down to the lake are presented . Included are the estimation and verification of an original unit of surfactant consumption per capita per day based on LAS and MBAS concentrations observed in diurnal monitoring . A simulation model representing the flowdown process of LAS dynamically is formulated, with which longitudinal dispersion, settling, and modified biodegradation of LAS are evaluated in the field survey . On the basis of the research scheme described above, ecotoxicological laboratory tests on ayu have been carried out . The special significance of acute and subchronic effects on ayu in various life stages exposed to low concentrations of LAS can be recognized . It has been concluded that the LC50 of young ayu is not greater than 0.1 ppm under the disadvantageous condition of high temperature or extreme hardness even in normal ranges of environmental indicators . An advanced plan of risk management for surfactant usage is proposed based on methods of elevated risk, comparative risk, risk--benefit, and balanced risk . The occurrence and magnitude of risk phenomena in each subdivided basin adjacent to the lake are identified, taking into consideration features such as (1) the spawning place of ayu and aquafarms, (2) COD and MBAS concentrations and their tolerable levels in current regulation of stream pollution, (3) socioeconomic perspectives including recreational activities and voluntary actions to improve the neighborhood environment, and (4) future preparation of measures for resolving technological risk including sewerage construction . Because LAS concentrations in several rivers exceed the tolerable level of the most delicate life stage of ayu, latent environmental effects can be suggested . It is concluded therefore that it is necessary to establish a water quality goal related to surfactants that takes patterns of water use and conservation of the ecosystem in the local environment into consideration . These judgments are followed by formulation of the "requirement" for environmental management practice for the Lake Biwa administration. Anesth Analg, 1988 Mar, 67(3), 240 - 6 Interactions of vecuronium and atracurium in an in vitro nerve-muscle preparation; Van der Spek AF et al.; Atracurium and vecuronium were compared when given alone and in combination in the in vitro rat phrenic nerve-hemidiaphragm preparation stimulated via the phrenic nerve . The slopes of the log dose response curves of atracurium and vecuronium were parallel; their ED50s were 1.12 +/- 0.0035.10(-5)M and 5.89 +/- 0.16.10(-6)M, respectively . The combination's log dose response curves were significantly shifted to the left when compared with those of either relaxant alone; an increased potency is displayed by the combination . These observations indicate nondepolarizing muscle relaxant synergy for the combination of equal proportions of vecuronium and atracurium . The synergistic interaction of vecuronium and atracurium in this in vitro-model is not dependent on pharmacokinetic factors such as uptake, distribution, and biodegradation as are present in the in vivo animal models and in humans . Synergy of vecuronium and atracurium in vitro is a new finding and is consistent with hypotheses of multiple receptor sites and different modes of action of the "competitive" neuromuscular blocking agents . This degree of synergy, seen in the in vitro animal data, if extrapolatable to humans, is probably of little clinical significance. Ecotoxicol Environ Saf, 1988 Feb, 15(1), 31 - 45 Availability of organic chemicals for biodegradation in settled bottom sediments; Shimp RJ et al.; Biodegradation rates for dodecyltrimethylammonium chloride (TMAC), a quaternary ammonium compound, and phenol were measured in settled sediments to determine if adsorbed chemicals were directly available for biodegradation by sediment-associated bacteria . In settled sediment cores, biodegradation rates for TMAC, which is charged at environmental pH, was a function of the amount of unadsorbed chemical; adsorbed material was not directly degraded by the sediment-associated bacteria . However, the rate of biodegradation of adsorbed phenol, a relatively hydrophobic and neutral chemical, was apparently a function of the total concentration of material present, suggesting that at least a fraction of the adsorbed material was directly degraded . These results indicate that chemical structure and, possibly, the mechanism of adsorption may influence biodegradation in sediments . Studies on TMAC biodegradation in completely mixed sediment/water slurries (up to 10 g/liter sediment) showed that TMAC biodegradation in slurries differed from that in settled sediments . Biodegradation in slurries was a function of the total amount of material present, both adsorbed and unadsorbed . These results suggest that biodegradation in settled sediments may be influenced by high concentrations of sediment present and/or the lack of mixing . Thus mixed, low-sediment-level slurries may not be realistic surrogates for modeling biodegradation processes in settled bottom sediments. Br J Surg, 1988 Feb, 75(2), 132 - 4 Cytotoxic-loaded albumin microspheres: a novel approach to regional chemotherapy; McArdle CS et al.; Adriamycin-loaded albumin microspheres (15-40 micron diameter) incorporating 1 per cent by weight of Adriamycin were prepared by cross linking albumin with glutaraldehyde . After systemic administration in rats, the microspheres were trapped in the pulmonary capillary bed, biodegradation occurring over 48 h . After selective intrarenal arterial injection of 99mTc-labelled albumin microspheres in rabbits, 97 per cent of the injected microspheres were trapped within the kidney; less than 1 per cent were found in the contralateral kidney, lungs and liver . Similar results were obtained after selective intrahepatic arterial injection . The selective injection of cytotoxic-loaded microspheres may provide a reliable method of administering high concentrations of cytotoxic drug to a target organ without producing high serum levels; this technique may have a role in the management of solid tumours. Microbiol Sci, 1988 Feb, 5(2), 36 - 41 (An)aerobic breakdown of chelating agents used in household detergents; Egli T; One of the main causes of the world-wide eutrophication of rivers and lakes is the extensive use of phosphate in both detergents and agricultural fertilizers . Partial or total substitution of phosphates in household detergents by other compounds exhibiting chelating properties has been introduced in several countries to ameliorate such problems . Various microbiological aspects of the biodegradation of the complexing agents most frequently used such as aminopolycarboxylates, phosphonates, hydroxycarboxylates and polymeric polycarboxylates, as well as tripolyphosphates, are reviewed. Appl Environ Microbiol, 1988 Feb, 54(2), 548 - 54 Aerobic biomineralization of alpha-hexachlorocyclohexane in contaminated soil; Bachmann A et al.; The factors identified to be important for the aerobic biodegradation of alpha-hexachlorocyclohexane (alpha-HCH) in a soil slurry are temperature, auxiliary carbon source, substrate concentration, and soil inhomogeneities . Temperatures in the range of 20 to 30 degrees C were determined to be most favorable for biodegradation of alpha-HCH . No alpha-HCH biodegradation was detected at temperatures below 4 degrees C and above 40 degrees C . The addition of auxiliary organic carbon compounds showed repressive effects on alpha-HCH biomineralization . Increased oxygen partial pressures reduced the repressive effects of added auxiliary organic carbon compounds . A linear relationship between alpha-HCH concentration and its conversion rate was found in a Lineweaver-Burk plot . Inhomogeneities such as clumping of alpha-HCH significantly affected its biodegradation . Inhomogeneity as an influence on biodegradation has not drawn sufficient attention in the past, even though it certainly has affected both laboratory studies and the application of biotechnological methods to clean up contaminated sites . On the basis of metabolites detected during degradation experiments, the initial steps of aerobic alpha-HCH bioconversion in a soil slurry are proposed. Basic Life Sci, 1988, 45, 203 - 9 Preliminary development of a bench-scale treatment system for aerobic degradation of trichloroethylene; Nelson MJ et al.; Our results have demonstrated that TCE may be biodegraded to nontoxic products under certain conditions . Trichloroethylene is apparently degraded by strain G4 to CO2, cellular carbon, and inorganic chloride . This activity requires aerobic conditions and exposure of the organism to certain aromatic compounds . This exposure is required to induce the bio-synthesis of one or more enzymes that fortuitously degrade TCE . The normal function of the enzyme(s) is the metabolism of the aromatic compounds . Evidence from the work with environmental samples indicates that the natural microflora in a variety of areas is capable of TCE degradation if stimulated by the appropriate aromatic compounds . These results are presently being applied to the development of bench-scale continuous treatment systems for further assessment of biodegradation as a means for detoxification of TCE-contaminated sites. Exp Gerontol, 1988, 23(4-5), 327 - 47 Biochemical markers of aging; Stadtman ER; It is the purpose of this report to identify possible metabolic deficiencies that might serve as biochemical markers of aging . It is proposed that the multiplicity of physical and physiological changes associated with aging could be most readily explained by alterations in the regulation and/or the activities of enzymes that occupy central positions in metabolism . Specifically, a search for metabolic markers of aging might include efforts to determine if there are age-related changes in the following enzymes or enzyme systems: (a) allosteric enzymes that catalyze reactions in highly branched metabolic pathways; (b) enzymes that catalyze opposing reactions between metabolites that are common intermediates in biosynthetic and biodegradative pathways (reactions which in the absence of final control would lead to futile substrate cycling); (c) enzymes that catalyze bimolecular reactions in which one member of a coenzyme pair is a cosubstrate (e.g., reactions involving NAD+ or NADH); (d) enzymes that are regulated by phosphorylation/dephosphorylation cycles; and (e) G-protein-dependent enzyme systems . It is also emphasized that changes in the concentrations and ratios of coenzyme substrate pairs (e.g., {NAD}/{NADH}, {CoA}/{acyl CoA}) and the energy charge ratio {ATP} + 0.5 {ADP}/{ATP} + {ADP} + {AMP} may signal deviations from normal metabolism and therefore might be reliable markers of aging . In addition, because of their critical roles in metabolism, changes in the concentration of GTP, GDP and the second messengers, c-AMP, c-GMP should be monitored . Finally, it is noted that the accumulation of the altered forms of some enzymes which occurs during aging reflects imbalance between posttranslational modification of the enzymes and the degradation of the altered enzyme forms . The biological mechanisms involved and the genetic implications are discussed. Eur Surg Res, 1988, 20(1), 12 - 7 Polyester arterial grafts impregnated with cross-linked albumin: the rate of degradation of the coating in vivo; Ben Slimane S et al.; One of the techniques used to avoid preclotting a porous textile arterial prosthesis is to coat the graft with a layer of a bioerodible polymer . The efficacy of this treatment is dependent in part on the rate at which the polymer degrades after implantation . The focus of this study was therefore to investigate the rate of in vivo degradation of albumin-coated polyester (Dacron)-knitted vascular prostheses . Two types of cross-linked albumin were included: one using glutaraldehyde, the other using carbodiimide as the cross-linking agent . Radioactively labeled albumin-coated prostheses were implanted in the thoracic aorta and peritoneal cavity of dogs, and their rates of biodegradation in vivo were monitored over a 4-week period . The rate of biodegradation was found to depend upon the site of implantation . It occurred more rapidly in the peritoneal cavity where less than 20% of the albumin coating remained after 4 weeks in vivo in comparison to the approximately 30% in the thoracic aorta . The nature and intensity of the cellular response appeared to be related to the cytotoxic potential of the cross-linking agent . Glutaraldehyde induced an inflammatory response and a delay in healing, whereas carbodiimide caused only a mild tissue reaction. Biomaterials, 1988 Jan, 9(1), 116 - 20 Biodegradable hollow fibres for the controlled release of drugs; Schakenraad JM et al.; Biodegradable hollow fibres of poly-L-lactic acid (PLLA) filled with a suspension of the contraceptive hormone levonorgestrel in castor oil were implanted subcutaneously in rats to study the rate of drug release, rate of biodegradation and tissue reaction caused by the implant . The in vivo drug release was compared with the release in vitro using different release media . Fibres, disinfected with alcohol showed a zero-order release, both in vitro and in vivo, for over 6 months . Fibres, either gamma-sterilized or disinfected with alcohol were harvested at time intervals ranging from 1 d to 6 months after implantation . Molecular weights of PLLA, tensile strengths, and remaining amounts of drug were determined as a function of time . The tissue reaction can be described as a very moderate foreign body reaction with the initial presence of macrophages, which are gradually replaced by fibroblasts which form a collagen capsule . Molecular weight determinations of PLLA showed a decrease from an initial Mw of 1.59 X 10(5) to 5.5 X 10(4) in 4 months (after alcohol sterilization) . A gradual decrease in fibre strength with time was observed which did not significantly impair the release rate of levonorgestrel. Appl Environ Microbiol, 1988 Jan, 54(1), 212 - 7 Influence of inorganic and organic nutrients on aerobic biodegradation and on the adaptation response of subsurface microbial communities; Swindoll CM et al.; The influence of inorganic and organic amendments on the mineralization of ethylene dibromide, p-nitrophenol, phenol, and toluene was examined in subsurface soil samples from a pristine aquifer near Lula, Okla . The responses indicate that the metabolic abilities and nutrient requirements of groundwater microorganisms vary substantially within an aquifer . In some samples, additions of inorganic nutrients resulted in a more rapid adaptation to the test substrate and a higher rate of metabolism, indicating that metabolism may have been limited by these nutrients . In other samples from the same aquifer layer, inorganic amendments had little or no influence on mineralization . In general, the addition of multiple inorganic nutrients resulted in a greater enhancement of degradation than did the addition of single substances . Additions of alternate carbon sources, such as glucose or amino acids, inhibited the mineralization of the xenobiotic substrates . This inhibition appears to be the result of the preferential utilization of the more easily degradable carbon amendments. Crit Rev Ther Drug Carrier Syst, 1988, 5(3), 171 - 87 Materials and biological aspects of synthetic polymers in controlled drug release systems: problems and challenges; Bruck SD et al.; The physico-chemical and biological aspects of polymeric materials represent vital areas in the reliable, safe, and efficacious functioning of controlled drug-delivery devices . In the case of implantable systems, potential biological problems include incompatibility of the polymers and their degradation products with the physiological environment, adverse metabolic consequences of the degradation products, and occlusion of the drug conduits (catheters) with thrombi and/or drugs, (i.e., insulin aggregates) . In the case of transcutaneous drug delivery systems, proper consideration must be given to avoid skin irritation and allergic responses as well as other toxic effects . With biodegradable systems that may follow simple hydrolysis and/or enzyme-catalyzed degradation of labile chemical side-chains that hold the drug molecule and/or the main polymer chain, increased attention must be given not only to the short-term but also the long-term metabolic consequences of the degradation products . Although the term "biodegradation" is often used for in vitro situations it should be reserved only for in vivo circumstances as, at the present time, no in vitro experiments can completely simulate the in vivo environment . The misuse of this term may lead to premature predictions as to the performance of a device in vivo, a situation that ought to be avoided . Appropriate atten