Biodegradation

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 attention must also be given to the effect of drugs on polymers as drug/polymer interactions may influence the stability of both the polymers and drugs and may result in altered therapeutic performance . Standards are needed to clearly differentiate between controlled drug delivery systems and older "sustained" and "time-release" preparations.

Basic Life Sci, 1988, 45, 143 - 62
Bioengineering issues related to in situ remediation of contaminated soils and groundwater; McCarty PL; This chapter presents some of the engineering challenges in biological degradation of organic contaminants in surface soils and the subsurface environment . Extraction of contaminants from the subsurface is generally costly, slow, and difficult . This has led to an interest in using in situ techniques for biodegradation of contaminants . For some contaminants that can be readily used as primary energy sources for bacteria with or without the presence of oxygen, bacterial removal is relatively simple and, in some situations, occurs naturally . In other cases, such as hydrocarbon spills, in situ treatment is still attractive, but has the added cost and difficulty of supplying required oxygen and nutrients for the fairly efficient aerobic oxidation . There are some indications that hydrocarbons may be biodegraded in the absence of oxygen; but, in these cases, the rates of degradation appear to be slow . More research in this area is desirable . The major challenge to both engineers and scientists lies in the decomposition of hazardous chemicals that appear to be transformed by the process of co-metabolism, or else are so low in concentration that they can only serve as secondary substrates . In either case, primary substrates are required to supply the major energy requirements for bacterial growth and/or for activation of enzymes necessary for the transformation . Engineering experience in the utilization of such processes for degradation of contaminants in the environment is very limited . Little is currently known about substrate interactions and how to optimize the bacterial transformations . Chemical requirements for achieving co-metabolism are high . In addition, knowledge is lacking about methods for getting the correct amounts of chemicals to the locations where needed and in the form needed . The solution of these important issues presents a significant challenge to the engineering and science communities, requiring both basic laboratory studies and field demonstrations in well-characterized environments.

Ecotoxicol Environ Saf, 1987 Dec, 14(3), 239 - 51
A shake-flask test for estimation of biodegradability of toxic organic substances in the aquatic environment; Cripe CR et al.; Disadvantages of current biodegradation tests are examined: the need for high substrate concentrations, lack of parent compound concentration measurements, no estimation of sediment effects, failure to indicate compounds to which microbial populations must adapt to degrade, and lack of site specificity in innocula selection . A modified river die-away test is proposed for determining biodegradability of organic compounds and testing for toxic degradation products . The present test uses shake flasks containing sterile (2% formalin) and nonsterile site water: both with, and without, site sediment (500 mg/liter) . Concurrent toxicity testing with mysids or daphnids provides a sensitive assay for the detection of toxic metabolites . Examples of three test compounds are given: methyl parathion, which undergoes rapid, sediment-mediated biodegradation; dibutylphthalate, to which some microbial communities exhibit an adaptation phenomenon; and methoxychlor, which has a relatively low water solubility and high sediment partition coefficient . The relative merits of this test procedure are discussed.

Ecotoxicol Environ Saf, 1987 Dec, 14(3), 223 - 30
Comparison of OECD and radiolabeled substrate methods for measuring biodegradation in marine environments; Shimp RJ et al.; Two methods for assessing biodegradation in marine environments, the OECD method, and a method using radiolabeled test substrate, were compared utilizing a model aromatic compound, benzoic acid . In samples from a relatively unimpacted estuary, Santa Rosa Sound, definitive biodegradation at 20 mg/liter was not detected by either method . However, the radiolabeled substrate method measured rapid biodegradation of the material at 50 micrograms/liter, which approximates expected environmental concentrations . In the Fraser River Estuary, which receives large discharges of municipal wastewater, biodegradation of benzoic acid was rapid at both 20 mg/liter and 50 micrograms/liter, and was detected by both methods . The results of the study illustrate the utility of radiolabeled substrates for determining the biodegradation of synthetic chemicals . Methods such as the OECD technique are very useful screening tools for assessing the overall potential of a chemical to biodegrade . However, such techniques generally cannot measure biodegradation at realistic concentrations . The use of radioisotopes in biodegradation studies can significantly increase the sensitivity of biodegradation measurements . As a result, realistic estimates of biodegradation can be obtained at concentrations which are often outside the scope of screening methods.

J Biomed Mater Res, 1987 Dec, 21(12), 1383 - 93
Use of chemically purified and cross-linked bovine pericardium as a ligament substitute; Chvapil M et al.; This study tested the reaction of a periarticular tissue to implanted pericardial membrane, substituting a segment of patellar ligament . Bovine pericardium was chemically purified and cross-linked with monomeric glutaraldehyde under pH, temperature and time conditions minimizing the polymerization of the cross-linking agent . Eight rats had both knee joint patellar ligaments excised . One side served as a control (simple suture), the other dissected ligament was replaced with a strip of pericardium . After 18 days and 12 weeks the dissected ligaments were analyzed by morphological methods . An unexpected fast ingrowth of cells and vessels was observed at 18 days . At 12 weeks new collagen deposits within pericardial patch were seen with striking biodegradation of the implant . Thus, using a new method of cross-linking the collagenous matrix with glutaraldehyde we see no evidence of glutaraldehyde cytotoxicity, as documented by our previous work.

J Biomed Mater Res, 1987 Dec, 21(A3 Suppl), 299 - 318
Experimental evaluation of amylose succinate absorbable hemostat in a canine model; Largis JK et al.; Using a semiquantitative animal model of standardized injuries to parenchymatous organs resulting in a range of degrees of hemorrhage, we compared freeze-dried amylose succinate topical hemostat to the most widely used commercially available products . Hemostatic efficacy parameters included bleeding time, blood loss, incidence of rebleeding, and amount of material used . Although no material was consistently superior in all parameters, in general amylose succinate and microcrystalline collagen performed equally well and both were significantly more effective than oxidized regenerated cellulose . Both amylose succinate and oxidized regenerated cellulose were superior to microcrystalline collagen, however, in biodegradation time, inflammatory response and adhesion-forming potential . Details of the animal model and an adhesion grading scheme are presented.

Ann Vasc Surg, 1987 Dec, 1(5), 542 - 7
Experimental and clinical experience with a gelatin impregnated Dacron prosthesis; Drury JK et al.; Laboratory and clinical evaluation of a knitted Dacron graft impregnated with gelatin to confer zero porosity is described . Graft performance was tested by standard methods for biodegradation of the sealant and in vitro thrombogenicity . The gelatin sealant was removed after seven to nine days and there was no platelet adhesion to Gelseal compared with unsealed Dacron . Animal experiments revealed normal macroscopic appearances in the graft and histological disappearance of the gelatin impregnate between five and ten days, allowing a cellular response similar to unsealed Dacron . The first 100 patients to have Gelseal aortic bifurcation graft implanted at Glasgow Royal Infirmary are described . The graft did not require preclotting . Blood transfusion was not necessary in 74% of patients . There is 100% patency at 21 months . A knitted Dacron graft sealed with gelatin is a safe, nonporous prosthesis at implantation.

Vopr Med Khim, 1987 Nov-Dec, 33(6), 114 - 8
{Biodegradation of lipids in ultrastructures of the rat liver during autolysis}; Golubev VP et al.; Dynamics of various lipids turnover was studied in ultrastructures of rat liver cells within various periods of autolysis in vitro . Under conditions of autolysis the lipid component in isolated liver cell ultrastructures was dissimilarly altered; the type of these alterations depended apparently on presence of corresponding acyl hydrolases, transacylases, lipoprotein lipases activated within various periods of autolysis.

Biomaterials, 1987 Nov, 8(6), 418 - 22
Basic aspects of the regeneration of small-calibre neoarteries in biodegradable vascular grafts in rats; Wildevuur CR et al.; In this report, an overview is given of the research concerning the development of a new type of small-calibre vascular graft: a hydrophilic, microporous, compliant, biodegradable graft is presented, which functions as a temporary scaffold for the regeneration of a new arterial wall (neoartery) . The basic healing process, the distinct effects of hydrophilicity, microporosity, compliance and biodegradation, the smooth muscle cell orientation and the effect of cell-seeding on this healing process in these grafts are described and discussed . It is concluded that vascular grafts, prepared from a material of optimal hydrophilicity, microporosity, compliance and rate of biodegradation, combined with smooth muscle and/or endothelial cell-seeding may provide a rapid development of a neoartery independent of the graft length.

Biochem Biophys Res Commun, 1987 Oct 14, 148(1), 148 - 52
Genetic characterization of an Escherichia coli mutant deficient in organophosphonate biodegradation; Loo SH et al.; An E . coli mutant deficient in organophosphonate biodegradation has been complemented with a cosmid library prepared from a BamHI partial digest of wild-type E . coli W3110 . Mutant E . coli SL724, when transformed with cosmid pSL163 and plasmid pSL263, regained the ability to exploit ethylphosphonate as a sole source of phosphorus during growth . In route to complementation, the Tn5 insert of SL724 was subcloned and restriction enzyme mapped . Complementing pSL163 and pSL263 were also characterized via restriction enzyme digests.

J Neurosurg, 1987 Oct, 67(4), 584 - 91
Mineralization and biodegradation of CSF shunting systems; Echizenya K et al.; The mineralization and biodegradation of cerebrospinal fluid shunting systems were studied using material from 25 shunts that had been implanted for between 6 days and 10 years . New unused materials were also examined for comparison . Surface changes in six systems could be observed under an operating microscope . Substantial quantities of a white deposit had adhered to the tubing in four of the shunts . These changes were most advanced in the galeal penetrative portion of the shunts and are believed to have been caused by mechanical stress . Scanning electron microscopic analysis revealed surface wrinkles, microscopic holes, and tiny particles, suggesting deterioration of the material itself . An energy-dispersive analysis using x-rays demonstrated that the surface deposits were due to mineralization of calcium phosphate and that the tiny particle growth was aluminum . These changes may be a consequence of the degradation of silicone rubber . A discriminant analysis of the mineralization was carried out; thus, the age of the host and the duration of system implantation could be correlated with the incidence of mineralization (p less than 0.1) . A measurement of the physical properties showed progressive change with a remarkable deterioration in systems implanted for more than 5 years.

Anesth Analg, 1987 Oct, 66(10), 983 - 5
Stability of I-653 in soda lime; Eger EI 3rd; Stability is an important characteristic of a halogenated volatile anesthetic because breakdown may produce toxic compounds . The resistance to breakdown by soda lime of a new halogenated volatile anesthetic, I-653, was compared with the resistances found for halothane, isoflurane, and sevoflurane . The four anesthetics were injected concurrently into flasks containing 500 ml of gas and 100 g of soda lime maintained at 40, 60, and 80 degrees C . Four or five flasks were tested at each temperature . The rate of anesthetic degradation increased as temperature increased . Degradation was greatest with sevoflurane and least with I-653 . At 80 degrees C, the rate of degradation per hr was 92.2 +/- 5% with sevoflurane; 16.0 +/- 1.6% with halothane; 13.1 +/- 3.7% with isoflurane; and 0.44 +/- 0.26% with I-653 (means +/- SD) . The in vitro stability of I-653 suggests that it may strongly resist biodegradation.

J Environ Pathol Toxicol Oncol, 1987 Sep-Dec, 7(7-8), 191 - 8
Prediction of breakthrough patterns of organics from laboratory tests; Baldauf G; The investigations have shown that it is possible to predict the breakthrough behavior of complex mixtures in a pilot-plant filter . The aim of future studies will be to predict the breakthrough behavior of waterworks filters in the same way as discussed here . This seems to be fairly simple if the filters are working with adsorption only . If, in addition, biological processes occur in a filter (as is generally observed), these processes have to be taken into account because an additional mechanism exists for removal of organic substances in the activated carbon filter . Investigations in a new research program will also need to consider the influence of ozone on biodegradation . Use of the methods already discussed, can help to optimize existing plants, as well as a proper control of the efficiency of the regeneration processes.

Appl Environ Microbiol, 1987 Sep, 53(9), 2001 - 8
Biodegradation of DDT {1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane} by the white rot fungus Phanerochaete chrysosporium; Bumpus JA et al.; Extensive biodegradation of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) by the white rot fungus Phanerochaete chrysosporium was demonstrated by disappearance and mineralization of {14C}DDT in nutrient nitrogen-deficient cultures . Mass balance studies demonstrated the formation of polar and water-soluble metabolites during degradation . Hexane-extractable metabolites identified by gas chromatography-mass spectrometry included 1,1,-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD), 2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol (dicofol), 2,2-dichloro-1,1-bis(4-chlorophenyl)ethanol (FW-152), and 4,4'-dichlorobenzophenone (DBP) . DDD was the first metabolite observed; it appeared after 3 days of incubation and disappeared from culture upon continued incubation . This, as well as the fact that {14C}dicofol was mineralized, demonstrates that intermediates formed during DDT degradation are also metabolized . These results demonstrate that the pathway for DDT degradation in P . chrysosporium is clearly different from the major pathway proposed for microbial or environmental degradation of DDT . Like P . chrysosporium ME-446 and BKM-F-1767, the white rot fungi Pleurotus ostreatus, Phellinus weirii, and Polyporus versicolor also mineralized DDT.

Biomaterials, 1987 Sep, 8(5), 407 - 10
Synthesis and biodegradation of polymers derived from aspartic acid; Pramanick D et al.; The synthesis of copolymers derived from aspartic acid hydrochloride, their characterization and their hydrolytic degradation and biodegradation by Aspergillus niger and E . coli have been described . The alpha-amino dicarboxylic acid has been copolymerized with 1,2-ethane diol, 1,3-butane diol, 1,4-butane diol, 1,6-hexane diol and glycerol to get copolyesters I, II, III, IV and V respectively . The polymer samples have been characterized by their number average molecular weight (Mn), elemental analysis and their i.r . spectra . The copolyester V is crosslinked . All of the copolyesters I-V undergo slow hydrolytic degradation in aqueous solution at ambient temperatures as studied by the measurement of the decrease in reduced viscosity and increase in specific conductance of their aqueous solutions . They are also degraded in aqueous suspension by the fungus Aspergillus niger and by the bacterium E . coli . Degradation by Aspergillus niger mainly depends on the polarity of the polymers, the more polar polymers being less degradable . On the other hand, degradation by E . coli is primarily dependent upon the alpha-NH2 group contents of the polymers, the alpha-NH2 group rich polymers being more degradable . The possible use of these polymers as biodegradable drug carriers has been suggested.

Appl Environ Microbiol, 1987 Sep, 53(9), 2212 - 7
Adaptation to and biodegradation of xenobiotic compounds by microbial communities from a pristine aquifer; Aelion CM et al.; The ability of subsurface microbial communities to adapt to the biodegradation of xenobiotic compounds was examined in aquifer solids samples from a pristine aquifer . An increase in the rates of mineralization of radiolabeled substrates with exposure was used as an indication of adaptation . For some compounds, such as chlorobenzene and 1,2,4-trichlorobenzene, slight mineralization was observed but no adaptation was apparent during incubations of over 8 months . Other compounds demonstrated three patterns of response . For m-cresol, m-aminophenol, and aniline intermediate rates of biodegradation and a linear increase in the percent mineralized with time were observed . Phenol, p-chlorophenol, and ethylene dibromide were rapidly metabolized initially, with a nonlinear increase in the percent mineralized with time, indicating that the community was already adapted to the biodegradation of these compounds . Only p-nitrophenol demonstrated a typical adaptation response . In different samples of soil from the same layer in the aquifer, the adaptation period to p-nitrophenol varied from a few days to as long as 6 weeks . In most cases the concentration of xenobiotic added, over the range from a few nanograms to micrograms per gram, made no difference in the response . Most-probable-number counts demonstrated that adaptation is accompanied by an increase in specific degrader numbers . This study has shown that diverse patterns of response occur in the subsurface microbial community.

Zentralbl Bakteriol Mikrobiol Hyg {B}, 1987 Aug, 184(6), 556 - 9
{Increase in the colony count in drinking water tanks caused by solvents from the coating material}; Frensch K et al.; As a freshly coated storage tank was put into operation a permanent colony increase in the drinking water (up to 7400 cfu/ml) could be detected . By chlorine dosage (30 mg/l) colony counts were reduced . From a second storage tank which had been coated at the same time bituminous coating material and air samples could be taken . After the exposure of the bituminous coating material in aqua bidest . 48 organic compounds were found by GC/MS-analysis . The main compounds were xylene, ethylbenzene and 1,2,4-trimethylbenzene . These compounds were also found by GC-investigations of the air-samples . The dependence between the used organic solvents and the colony increase could be demonstrated by biodegradation tests of solvent compounds . It was found that about 50 per cent of the identified compounds could be degraded by microorganisms and therefore caused a colony increase in drinking water.

Appl Environ Microbiol, 1987 Aug, 53(8), 1833 - 8
Physical and biological parameters that determine the fate of p-chlorophenol in laboratory test systems; Pritchard PH et al.; Shake-flask and microcosm studies were conducted to determine the fate of para-chlorophenol (p-CP) in water and sediment systems and the role of sediment and nonsediment surfaces in the biodegradation process . Biodegradation of p-CP in estuarine water samples in shake flasks was slow over incubation periods of 300 h . The addition of detrital sediment resulted in immediate and rapid degradation evidenced by the production of 14CO2 from {14C}p-CP . The addition of sterile sediment, glass beads, or sand resulted in approximately four to six times more CO2 evolution than observed in the water alone . Densities of p-CP-degrading bacteria associated with the detrital sediment were 100 times greater than those enumerated in water . Bacteria in the water and associated with the sediment after preexposure of both water and sediment of p-CP demonstrated enhanced biodegradation . In some microcosms, p-CP was degraded completely in the top 1.0 cm of intact sediment beds . Sediment reworking activities by benthic invertebrates from one site were sufficient to mix p-CP deep into the sediment bed faster than biodegradation or molecular diffusion . p-CP was persistent at lower depths of the sediment, possibly a result of reduced oxygen conditions preventing aerobic biodegradation.

Biomaterials, 1987 Jul, 8(4), 308 - 10
A plastic composite of alginate with calcium phosphate granulate as implant material: an in vivo study; Klein CP et al.; A comparison of calcium phosphate granulate with a composite of alginate and calcium phosphate granulate, shows that the composite has less particle migration, less biodegradation and better handling properties . The tissue response to both materials is similar.

Appl Environ Microbiol, 1987 Jul, 53(7), 1496 - 9
Effect of adaptation to phenol on biodegradation of monosubstituted phenols by aquatic microbial communities; Shimp RJ et al.; The adaptation of a mixed aquatic microbial community to phenol was examined in microcosms receiving phenol as a sole carbon source . Extended exposure (adaptation) to phenol resulted in adaptation of the microbial community to the structurally related aromatic compounds m-cresol, m-aminophenol, and p-chlorophenol . The increased biodegradation potential of the phenol-adapted microbial community was accompanied by a concurrent increase in the number of microorganisms able to degrade the three test compounds . Thus, adaptation to the three test chemicals was likely a growth-related result of extended exposure to phenol . The results indicate that adaptation to a single chemical may increase the assimilative capacity of an aquatic environment for other related chemicals even in the absence of adaptation-inducing levels of those materials.

Invest Radiol, 1987 Jul, 22(7), 590 - 6
Coralline hydroxyapatite bone-graft substitutes in a canine diaphyseal defect model . Radiographic-histometric correlation; Sartoris DJ et al.; Radiographic and histometric evaluation of a new form of bonegraft substitute derived from reef-building sea coral was performed in a canine diaphyseal defect model . Comparably sized blocks of this material and iliac crest autograft were placed into bilateral surgically created cortical windows in the distal radial diaphyses of 14 dogs . Representative graft specimens of both types underwent densitometric radiography and harvesting at 3, 6, 12, 24, and 48 months . Histometric analysis of implant specimens revealed satisfactory union and native osseous ingrowth at all time intervals . Graft specimens exhibited adequate union with scant host bone ingrowth at three months, but subsequent progressive appositional closure of cancellous spaces during the ensuing 45 months . Volume fraction and mean width of host bone remained stable in the implants but increased in the grafts due to neocortex formation . Stereologic distribution of bone was homogeneous in both implant and graft specimens, and no evidence for biodegradation of the former was observed . Corrected transmission density determinations accurately reflected these differences but correlated significantly with volume fractions and tissue widths of bone and soft tissue only in the autografts . These results support the successful early application of coralline hydroxyapatite bone graft substitutes as an alternative to autogenous grafting in the clinical setting and emphasize the potential role of noninvasive densitometric techniques in monitoring the incorporation of bone-graft materials.

Neuroscience, 1987 Jul, 22(1), 233 - 6
Phelorphan, an inhibitor of enzymes involved in the biodegradation of enkephalins, affected the withdrawal symptoms in chronic morphine-dependent rats; Haffmans J et al.; Intracerebroventricular administration of phelorphan (158 nmol/2 microliters), a blocker of dipeptidylaminopeptidase (enkephalinase B) and other enzymes involved in the enkephalin biodegradation, inhibited in chronic morphine-dependent rats, the occurrence of some of the naloxone-precipitated withdrawal symptoms . This effect of phelorphan was compared with an equimolar dose of the dipeptidyl-carboxypeptidase inhibitor (enkephalinase A), thiorphan . The results indicate that both drugs decrease some of the naloxone-precipitated withdrawal symptoms (writhing, digging, head hiding, chewing, diarrhoea and Straub tail), while others were potentiated (penile licking) or unaltered (wet dog shakes, grooming and rearing) . In addition, phelorphan compared with the controls or thiorphan, pretreated animals, increased the frequency of paw tremor, head shakes, scratching, erection and ejaculation, but other symptoms were decreased (stretching) or unaltered (teeth chattering) . The results are discussed in light of the differences in permeability and specificity of the two enkephalinase inhibitors . Furthermore, these data support the hypothesis that the use of enkephalinase inhibitors might be a promising way for the attenuation of the severity of the withdrawal syndrome.

Proc Natl Acad Sci U S A, 1987 Jul, 84(13), 4423 - 7
Biosynthesis of polyamines in ornithine decarboxylase, arginine decarboxylase, and agmatine ureohydrolase deletion mutants of Escherichia coli strain K-12; Panagiotidis CA et al.; Escherichia coli K-12 mutants that carry deletions in their genes for ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) (speC), arginine decarboxylase (L-arginine carboxy-lyase, EC 4.1.1.19) (speA), and agmatine ureohydrolase (agmatinase or agmatine amidinohydrolase, EC 3.5.3.11) (speB) can still synthesize very small amounts of putrescine and spermidine . The putrescine concentration in these mutants was found to be 1/2500th that in spe+ cells . The pathway of putrescine synthesis appears to be through the biodegradative arginine decarboxylase, which converts arginine to agmatine, in combination with a low agmatine ureohydrolase activity--1/2000th that in spe+ strains . These results suggest that even such low levels of polyamines permit a low level of protein synthesis . Evidence is presented that the polyamine requirement for the growth of the polyamine-dependent speAB, speC deletion mutants, which are also streptomycin resistant, is not due to a decreased ability to synthesize polyamines.

Biochem Biophys Res Commun, 1987 Jun 15, 145(2), 775 - 81
Rapid enzymatic degradation of {125I} (Tyr 10) FGF (1-10) by serum in vitro and involvement in the determination of circulating FGF by RIA; Gauthier T et al.; In the conditions used in the RIA procedure for circulating FGF quantitation, the tracer {125I} (Tyr 10) FGF (1-10) was extensively degraded into two non immunoreactive peptides corresponding to a sequential removal of two amino acid residues at the NH2-terminus i.e . Pro and Ala . A FGF like immunoreactive fraction exists in serum the molecular weight of which was estimated to be 240 Kda . This fraction was also able to perform the same extensive degradation of (Tyr 10) FGF (1-10) than whole serum . The results presented raise the question of the validity of RIA for the determination of circulating FGF . They also present evidence that a high molecular weight serum fraction which reacts as immunoreactive FGF is an enzymatic activity responsible for biodegradation of the growth factor rather than a distinct biological entity which is related to the FGF structure.

Cryobiology, 1987 Jun, 24(3), 214 - 28
Vitrification in plants as a natural form of cryoprotection; Hirsh AG; A small group of woody plants from the far northern hemisphere can, while in the dormant state, tolerate freezing and thawing to and from any subzero temperature at rates less than 30 degrees C/hr . In addition, the hardiest of them can tolerate cooling and warming between -20 degrees C and any colder temperature at virtually any combination of rates subsequent to cooling to -20 degrees C at rates less than 5 degrees C/hr . We term this latter capability "quench hardiness." I and my colleagues have shown that the limits of this quench hardiness can be closely correlated to the stability of intracellular glasses formed during the slow cooling of hardy tissues in the presence of extracellular ice . In this paper, I briefly review the evidence for intracellular glass formation and present data indicating that major components of the glass forming solutions are raffinose and stachyose . Evidence from differential scanning calorimetry that sugar-binding soluble proteins are also important is presented . Finally, I correlate data from our work with that of other workers to make the case that, even when most of a cytoplasmic solution is vitrified, fluid microdomains remain which can lead to long-term biodegradation during storage at high subzero temperatures.

J Biomed Mater Res, 1987 Jun, 21(6), 741 - 71
Chemically modified collagen: a natural biomaterial for tissue replacement; Nimni ME et al.; Glutaraldehyde crosslinking 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 crosslinks . Tissues crosslinked with glutaraldehyde retain many of the viscoelastic properties of the native collagen fibrillar network which render them suitable for bioprostheses . Implants of collagenous materials crosslinked with glutaraldehyde are subject long-term to calcification, biodegradation, and low-grade immune reactions . We have attempted to overcome these problems by enhancing crosslinking through bridging of activated carboxyl groups with diamines and using glutaraldehyde to crosslink the epsilon-NH2 groups in collagen and the unreacted amines introduced by aliphatic diamines . This crosslinking reduces tissue degradation and nearly eliminates humoral antibody induction . Covalent binding of diphosphonates, specifically 3-amino-1-hydroxypropane-1, 1-diphosphonic acid (3-APD), and chondroitin sulfate to collagen or to the crosslink-enhanced collagen network reduces its potential for calcification . Platelet aggregation is also reduced by glutaraldehyde crosslinking and nearly eliminated by the covalent binding of chondroitin sulfate to collagen . The cytotoxicity of residual glutaraldehyde--leaching through the interstices of the collagen fibrils or the tissue matrix--and of reactive aldehydes associated with the bound polymeric glutaraldehyde can be minimized by neutralization and thorough rinsing after crosslinking and storage in a nontoxic bacteriostatic solution.

Biomed Environ Mass Spectrom, 1987 Jun, 14(6), 275 - 80
GC/MS identification of organosulphur compounds in environmental samples; Headley JV; Twenty-one organosulphur compounds were detected in a survey of water, industrial effluent, sediment and fish samples, using automated gas chromatography/mass spectrometry developed for the identification of forty target semi-volatile and volatile organosulphur compounds . The compound classes detected in the environmental samples are three allotropes of sulphur, three thioethers, five sulphones, six thiophenes, one thiol, two sulphonamides and one thiazole . The compounds were detected in the approximate concentration range 0.1 to 2000 parts per billion (ppb) . alpha,alpha-Dichlorodimethyl sulphone was detected in environmental samples subjected to biodegradation and chemical treatment.

Appl Environ Microbiol, 1987 May, 53(5), 949 - 54
Biodegradation of trichloroethylene and involvement of an aromatic biodegradative pathway; Nelson MJ et al.; Biodegradation of trichloroethylene (TCE) by bacterial strain G4 resulted in complete dechlorination of the compound, as indicated by the production of inorganic chloride . A component of the water from which strain G4 was isolated that was required for TCE degradation was identified as phenol . Strain G4 degraded TCE in the presence of chloramphenicol only when preinduced with phenol . Toluene, o-cresol . and m-cresol could replace the phenol requirement . Two of the inducers of TCE metabolism, phenol and toluene, apparently induced the same aromatic degradative pathway that cleaved the aromatic ring by meta fission . Cells induced with either phenol or toluene had similar oxidation rates for several aromatic compounds and had similar levels of catechol-2,3-dioxygenase . The results indicate that one or more enzymes of an inducible pathway for aromatic degradation in strain G4 are responsible for the degradation of TCE.

Appl Environ Microbiol, 1987 May, 53(5), 1064 - 8
Alternative nonlinear model for estimating second-order rate coefficients for biodegradation; Suflita JM et al.; A modification of the second-order model for biodegradation was derived, applied to an example data set, and shown to be superior for describing the anaerobic biodegradation of p-cresol by an enriched bacterial consortium . The modified model circumvents the no-growth assumption implicit in the use of the second-order rate equation, but still requires the assumption of first-order kinetics over the course of substrate depletion . Violation of the no-growth assumption is particularly important since overestimates of the pseudo-first-order rate coefficient lead to underestimates of the time required for the removal of a xenobiotic chemical from a contaminated environment . Our calculations show that the errors introduced into the pseudo-first-order rate coefficient (and the resulting estimates of the second-order rate coefficient) approach 100% if one doubling occurs in activity over the course of substrate depletion . For an exemplary data set, use of a first-order model resulted in a 100% overestimate of the first-order decay coefficient, which would in turn lead to a corresponding overestimate of the second-order rate coefficient . The modified model we describe is a potential alternative to the pseudo-first-order model for the routine estimation of second-order rate coefficients.

Nature, 1987 Apr 2-8, 326(6112), 520 - 3
Cloning and sequencing of a cDNA for a ligninase from Phanerochaete chrysosporium; Tien M et al.; Lignin is a complex polymer of phenylpropanoid subunits . It is an essential component of woody tissue, to which it imparts structural rigidity . Lignin is remarkably resistant to degradation by most microbes; nevertheless, a few species of white-rot fungi are able to catalyse its oxidation to CO2 . Its biodegradation is of great ecological significance because, next to cellulose, lignin is the most abundant renewable polymer on Earth . The first step in lignin degradation is depolymerization, catalysed by the lignin peroxidase isozymes (ligninases) . These isozymes are secreted, along with hydrogen peroxide (H2O2) by the fungus Phanerochaete chrysosporium Burds, under conditions of nutrient (nitrogen) limitation . Ligninases are not only important in lignin biodegradation, but are also potentially valuable in chemical waste disposal because of their ability to degrade environmental pollutants . We have undertaken the cloning of the ligninase genes to understand further their regulation and enzymology . We report here the isolation and characterization of a ligninase complementary DNA clone with a full-length insert . The cDNA sequence shows that the sequence of the mature ligninase is preceded by a 28-residue leader, and the mature protein is predicted to have a relative molecular mass of 37,000 (Mr 37K) . Consistent with the classification of ligninase as a peroxidase certain residues thought to be essential for peroxidase activity can be identified and near these residues the ligninase shows homology with other known peroxidases . Our cDNA clone has also allowed us to show that expression of ligninase is regulated at the messenger RNA level.

Appl Environ Microbiol, 1987 Apr, 53(4), 710 - 6
Biodegradation of cresol isomers in anoxic aquifers; Smolenski WJ et al.; The biodegradation of o-, m-, and p-cresol was examined in material obtained from a shallow anaerobic alluvial sand aquifer . The cresol isomers were preferentially metabolized, with p-cresol being the most easily degraded . m-Cresol was more persistent than the para-isomer, and o-cresol persisted for over 90 days . Biodegradation of cresol isomers was favored under sulfate-reducing conditions (SRC) compared with that under methanogenic conditions (MC) . Slurries that were acclimated to p-cresol metabolism transformed this substrate at 18 and 330 nmol/h per g (dry weight) for MC and SRC, respectively . Inhibition of electron flow to sulfate reduction with 2.0 mM molybdate reduced p-cresol metabolism in incubations containing sulfate . When methanogenesis was blocked with 5 mM bromoethanesulfonic acid in incubations lacking sulfate, p-cresol catabolism was retarded . Under SRC 3.4 mol of sulfate was consumed per mol of p-cresol metabolized . The addition of sulfate to methanogenic incubations stimulated p-cresol degradation . Simultaneous adaptation studies in combination with spectrophotometric and chromatographic analysis of metabolites indicated that p-cresol was oxidized under SRC to p-hydroxybenzoate via the corresponding alcohol and aldehyde . This series of reactions was inhibited under sulfate-limited or aerobic conditions . Therefore, the primary catabolic event for p-cresol decomposition under SRC appears to involve the hydroxylation of the aryl methyl group.

J Biomater Appl, 1987 Apr, 1(4), 487 - 501
The in vivo biodegradation of nylon 6 utilized in a particular IUD; Hudson JA et al.; The particular IUD of this study was composed of a plastic shield and a nylon 6 coated filament tail string . This IUD was unique, in the fact that its tail string was the only one (and has been to date) that consisted of a coated multifilament arrangement . Studies on the tail string have revealed bacteria and debris existing between the outer filaments that are underneath the coating . Other studies have reported that removed devices were found to exhibit an unusually high incidence of breaks in the tail string coating . Studies at the University of Lowell also found that upon examination of devices that had been in vivo for periods of two years or longer, 67% of these devices examined had breaks in the coating of the tail string . Investigations have determined that the design of the tail string was serving as an avenue of transport for the bacteria to bypass the protective cervical mucus barrier and enter the sterile uterine cavity through the breaks in the tail string coating . This mechanism has been suggested to account for the higher frequency of uterine infections associated with this device . Research at the University of Lowell was undertaken to study the degradation of the nylon 6 coating and to determine the in vivo degradation mechanism . The biochemistry of the fluids present in the reproductive tract were carefully documented and the more aggressive ones selected for in vitro trials . The results of the study revealed that the in vivo physical breakdown of the coating may depend upon a series of mechanisms and variables.

Dev Biol, 1987 Apr, 120(2), 447 - 56
Sulfated glycosaminoglycans (GAG) in the developing mouse brain . Quantitative aspects on the metabolism of total and individual sulfated GAG in vivo; Burkart T et al.; Sulfation and desulfation of total glycosaminoglycans (GAG) as well as of chondroitin sulfates (A + C), dermatan sulfate, and heparan sulfate were quantified in the developing cerebrum and cerebellum of mice by labeling with {35S}sulfate combined with chases started 24 hr after {35S}sulfate injection . In both the developing cerebrum and cerebellum, the rate of biosynthesis of total sulfated GAG was highest shortly after birth (2 days), decreased sharply thereafter, and reached a plateau after 14 days . The biosynthetic activities of chondroitin sulfates and heparan sulfate decreased sharply up to 14 days and retained constant levels afterward . By contrast, the rates of biosynthesis of dermatan sulfate increased up to 14 days . The biodegradation rates of total sulfated GAG as well as of chondroitin sulfates, heparan sulfate, and dermatan sulfate were strongly correlated with the corresponding rates of biosynthesis during the first 2 postnatal weeks . Total and individual sulfated GAG showed high degradation rates resulting in half-life times of a few hours up to 1 1/2 days . Thus sulfated GAG are synthesized in excess and the actual net content seems to be co-regulated to a high degree by lysosomal degradation . In both brain parts, a proportional increase of the sulfated GAG content vs the total GAG content from 40% at birth to 90% at 28 days was observed . Since during development heparan sulfate and dermatan sulfate manifested a relative increase in their daily net synthesis besides a decrease of chondroitin sulfates, a developmental increase of the sulfate groups linked to GAG is evidenced . This molecular differentiation resulting in microenvironmental changes may be of high functional significance.

Eur J Pharmacol, 1987 Mar 31, 135(3), 411 - 8
Synthesis of enkephalinase B inhibitors, and their activity on isolated enkephalin-degrading enzymes; Van Amsterdam JG et al.; Compounds in which a dipeptide moiety is linked to a metal chelating mercapto group were synthesized to obtain effective enkephalinase B inhibitors . Inhibitors containing two hydrophobic amino acid side-chains decrease enkephalinase B activity with a potency depending on the length of the spacer connecting the mercapto group and the dipeptide (IC50 values vary between 0.35 and 14 microM) and they also inhibit enkephalinase A and aminopeptidase activity . Compounds lacking the carboxy terminal side-chain are not recognized by enkephalinase B or aminopeptidase but are potent inhibitors of enkephalinase A . Our most potent enkephalinase B inhibitor is mercaptoacetyl-Phe-Phe (designated phelorphan), having an IC50 value of 0.35 microM for enkephalinase B . This compound also effectively inhibits enkephalinase A (IC50 = 0.02 microM) and aminopeptidase activity (IC50 = 13 microM) . Phelorphan can therefore be considered as a complete inhibitor of enkephalin biodegradation.

Toxicol Ind Health, 1987 Mar, 3(1), 5 - 69
Health and environmental effects profile for pentachloronitrobenzene; Choudhury H et al.; Pure pentachloronitrobenzene (PCNB) is a colorless crystalline solid (Worthing, 1983) . The commercial product may have a light-yellow to cream color with a musty odor (Hartley and Kidd, 1983) . It is practically insoluble in a number of organic solvents . The compound is reasonably stable but may undergo hydrolysis in a strong alkaline medium (Hartley and Kidd, 1983) . In 1983, Olin Corp., Leland, MS, was the only manufacturer of PCNB in the United States (SRI, 1984; Hartley and Kidd, 1983) . No data for U.S . production volume for this chemical are available, but recent production source data (USITC, 1985; SRI, 1985) suggest that this chemical is no longer commercially produced in the United States . The primary usage of PCNB is as a soil fungicide for a wide variety of crops and in seed treatment (Worthing, 1983; Hartley and Kidd, 1983) . The fate of PCNB in water has not been comprehensively studied . Only qualitative data regarding fate and transport in water are available . The half-life of PCNB in the water phase was estimated to be 1.8 days . The two processes reported to be most responsible for the rapid decrease in PCNB concentration in water were volatilization and sorption to seston and biota, followed by sedimentation as detritus (Schauerte et al., 1982) . Neither biodegradation nor photolysis appears to be a significant process for the loss of PCNB from water (Crosby and Hamadmad, 1971; Schauerte et al., 1982) . The BCFs for PCNB in the golden orfe, Leucisens idus melanotus, and in rainbow trout, Salmo gairdneri, were reported to be 950-1130 and 260-590, respectively (Korte et al., 1978; Oliver and Niimi, 1985) . It therefore appears that PCNB will moderately bioaccumulate in aquatic organisms . Pertinent data regarding the fate and transport of PCNB in air could not be located in the available literature as cited in the Appendix . Based on its physical properties and its behavior in other media, it would appear that PCNB will persist in the atmosphere because no known chemical/photochemical processes significantly degrade this chemical . Precipitation of particulate PCNB, especially of larger particle size and higher particle density, may remove some PCNB from the atmosphere . PCNB is persistent in soils . The two processes that are important in the loss of PCNB from soils are volatilization and biodegradation; biodegradation is more rapid in soils under anaerobic conditions than under aerobic conditions (Ko and Farley, 1969; Casley, 1968; Gile and Gillett, 1979; Cole and Metcalf, 1977).(ABSTRACT TRUNCATED AT 400 WORDS)

Biomaterials, 1987 Mar, 8(2), 129 - 37
On the biodegradation of poly-beta-hydroxybutyrate (PHB) homopolymer and poly-beta-hydroxybutyrate-hydroxyvalerate copolymers; Miller ND et al.; The known biodegradability of PHB in certain biological environments has led to its proposed use as a 'biodegradable' implant material . Monofilaments of PHB homopolymer and two PHV-PHB copolymers have been studied in vivo and in vitro and assessed for changes in mechanical properties and topography . In vivo biodegradation was only observed with PHB when pre-degraded by 10.0 Mrad of gamma-irradiation before implantation . High temperature in vitro hydrolysis suggested that PHV copolymer additions retarded the rate of degradation of PHB . Hydration reactions had most effect on the ultimate tensile properties of the materials . In contrast, the elastic properties appeared to be relatively unaffected.

Clin Pharmacokinet, 1987 Mar, 12(3), 145 - 67
Clinical pharmacokinetics of the inhalational anaesthetics; Dale O et al.; At present, the most widely used inhalational anaesthetics are the halogenated, inflammable vapours halothane, enflurane, isoflurane and the gas nitrous oxide . The anaesthetic effect of these agents is related to their tension or partial pressure in the brain, represented at equilibrium by the alveolar concentration . The minimum alveolar concentration for a specific agent is remarkably constant between individuals . The uptake and distribution of inhalational anaesthetics depends on inhaled concentration, pulmonary ventilation, solubility in blood, cardiac output and tissue uptake . Inhalational anaesthetics are mainly eliminated by pulmonary exhalation, but significant amounts of halothane are removed by hepatic metabolism . Inhalational agents currently in use have acceptable pharmacokinetic characteristics, and clinical acceptance depends on their potential for adverse effects . Induction of anaesthesia with halothane is rapid and relatively pleasant and it is the agent of choice for paediatric anaesthesia . Between 20 and 50% is metabolised, and the parent drug is a potent inhibitor of drug metabolism . Post-operatively enzyme induction may follow . The major disadvantages of halothane are myocardial depression, propensity to evoke cardiac arrhythmias and the rare but serious halothane hepatitis . Induction and recovery from enflurane anaesthesia is rapid . Metabolism accounts for 5 to 9% of the elimination . The metabolic product inorganic fluoride may in rare cases cause renal toxicity . Enflurane is a weak inhibitor of drug metabolism at anaesthetic concentrations . Enflurane depresses circulation more than halothane by reducing both myocardial contractility and systemic vascular resistance, but cardiac rhythm is stable . Enflurane anaesthesia may, unlike the other agents, induce epileptic activity . Enflurane is widely used as replacement for halothane in adults . Despite its low blood-gas solubility, the airway irritability of isoflurane precludes a faster induction of anaesthesia than with halothane . Isoflurane is almost resistant to biodegradation . Myocardial contractility is maintained during isoflurane anaesthesia and cardiac rhythm is stable except for the occurrence of tachycardia in some patients . Isoflurane is the inhalational agent of choice for neurosurgical operations . Sevoflurane is an experimental ether vapour: induction and recovery is fast and pleasant . It is metabolised to the same extent as enflurane and subnephrotoxic concentrations of inorganic fluoride may result . Sevoflurane has fewer respiratory and cardiovascular depressant effects than halothane and may be a future alternative for paediatric anaesthesia.(ABSTRACT TRUNCATED AT 400 WORDS)

J Biomed Mater Res, 1987 Feb, 21(2), 231 - 46
Biodegradation of a polyurethane in vitro; Phua SK et al.; This study examines the effect of in vitro exposure to enzymes on the performance properties of Biomer, a segmented polyetherurethane used in a number of blood-contacting devices such as catheters, heart assist pumps, and chambers for artificial hearts . The ultrathin samples were treated with two proteolytic enzymes, papain and urease, for periods of 1-6 months at 37 degrees C . The treated Biomer samples were subjected to chemical and physical analysis . Effects of biodegradation by the enzymes were assessed by fatigue tests, gel permeation chromatography (GPC), and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) analysis . Papain was found to be more effective in degrading the polymer than urease . Mechanisms for enzymic degradation are proposed.

Pharmazie, 1987 Feb, 42(2), 107 - 8
In vivo interaction of spironolactone and phenobarbital with cholesterol; effect on cholesterol organ concentration; Rekka E et al.; In this work, the effect of pretreatment with spironolactone or phenobarbital on female Wistar rats after a chronic administration of cholesterol, upon the cholesterol concentration in blood, brain and liver was examined . It was found that the pretreatment reduced cholesterol in all tissues in the order, brain - plasma - liver . The findings were attributed to an increased biodegradation and disposition of cholesterol . It could also be concluded that after the pretreatment we may have a predominance of the catabolic and/or the disposition rather than of the synthetic and/or absorption processes for the steroid.

Eur J Cancer Clin Oncol, 1987 Feb, 23(2), 201 - 4
Effect of hyperthermia on spermidine/spermine N1-acetyltransferase activity in Ehrlich ascites cells; Matsui-Yuasa I et al.; When Ehrlich ascites tumor cells were incubated at 42 degrees C, the activity of spermidine/spermine N1-acetyltransferase, a rate-limiting enzyme of polyamine biodegradation, decreased to 20% of the control level within 1 hr . Protein synthesis, judged from the incorporation of {3H}leucine into the acid-insoluble fraction, was less affected by heat exposure . The decrease in the enzyme activity caused by heat treatment could be reversed by switching the incubation temperature back to 37 degrees C . The reversion of enzyme activity was suppressed by cycloheximide but not by actinomycin D.

Microbiol Sci, 1987 Feb, 4(2), 59 - 63
Problems and potential for in situ treatment of environmental pollutants by engineered microorganisms; Jain RK et al.; Molecular microbial ecology could provide tools for studying the structure and function of biodegradative microbial communities useful for in situ removal of environmental pollutants . Detection and monitoring of released organisms in the environment is required and DNA:DNA colony hybridization seems to be one of the highly sensitive and accurate technologies available for achieving this goal . A realistic and pragmatic view is required for analysis of the risks of environmental release of genetically-modified or engineered organisms.

Science, 1987 Jan 30, 235(4788), 593 - 6
Redesigning metabolic routes: manipulation of TOL plasmid pathway for catabolism of alkylbenzoates; Ramos JL et al.; Increasing quantities of man-made organic chemicals are released each year into the biosphere . Some of these compounds are both toxic and relatively resistant to physical, chemical, or biological degradation, and they thus constitute an environmental burden of considerable magnitude . Genetic manipulation of microbial catabolic pathways offers a powerful means by which to accelerate evolution of biodegradative routes through which such compounds might be eliminated from the environment . In the experiments described here, a catabolic pathway for alkylbenzoates specified by the TOL plasmid of Pseudomonas was restructured to produce a pathway capable of processing a new substrate, 4-ethylbenzoate . Analysis of critical steps in the TOL pathway that prevent metabolism of 4-ethylbenzoate revealed that this compound fails to induce synthesis of the catabolic enzymes and that one of its metabolic intermediates inactivates catechol 2,3-dioxygenase (C23O), the enzyme that cleaves the aromatic ring . Consequently, the pathway was sequentially modified by recruitment of genes from mutant bacteria selected for their production of either an altered pathway operon regulator that is activated by 4-ethylbenzoate or an altered C23O that is less sensitive to metabolite inactivation . The redesigned pathway was stably expressed and enabled host bacteria to degrade 4-ethylbenzoate in addition to the normal substrates of the TOL pathway.

Appl Environ Microbiol, 1987 Jan, 53(1), 129 - 36
Naphthalene biodegradation in environmental microcosms: estimates of degradation rates and characterization of metabolites; Heitkamp MA et al.; Naphthalene biodegradation was investigated in microcosms containing sediment and water collected from three ecosystems which varied in past exposure to anthropogenic and petrogenic chemicals . Mineralization half-lives for naphthalene in microcosms ranged from 2.4 weeks in sediment chronically exposed to petroleum hydrocarbons to 4.4 weeks in sediment from a pristine environment . Microbiological analysis of sediments indicated that hydrocarbon-utilizing microbial populations also varied among ecosystems and were 5 to 12 times greater in sediment after chronic petrogenic chemical exposure than in sediment from an uncontaminated ecosystem . Sediment from an ecosystem exposed to agricultural chemicals had a mineralization half-life of 3.2 weeks for naphthalene and showed about a 30-fold increase in heterotrophic bacterial populations in comparison to uncontaminated sediments, but only a 2- to 3-fold increase in hydrocarbon-degrading bacteria . Analysis of organic solvent-extractable residues from the microcosms by high-pressure liquid chromatography detected polar metabolites which accounted for 1 to 3% of the total radioactivity . Purification of these residues by thin-layer chromatography and further analysis by gas chromatography-mass spectrometry indicated that cis-1,2-dihydroxy-1,2-dihydronaphthalene, 1-naphthol, salicylic acid, and catechol were metabolites of naphthalene . These results provide useful estimates for the rates of naphthalene mineralization in different natural ecosystems and on the degradative pathway for microbial metabolism of naphthalene in freshwater and estuarine environments.

Int J Environ Anal Chem, 1987, 29(3), 153 - 78
{Evolution of hydrocarbons and bacterial activity in the marine sediments contaminated by crude oil overflow and treated}; Bodennec G et al.; The fate of an experimental oil pollution of intertidal sediments in a sheltered beach of North Brittany (France) has been investigated over a 16-month period . Chemical treatments were applied to two of the three contaminated plots by pre-mixing oil respectively with dispersant and biodegrading agents . The physico-chemical and bacteriological characteristics of the polluted areas were followed with the purpose of identifying the limiting parameters for oil microbial degradation and the effect of treatment . The concentration of hydrocarbons in the oiled sediments did not change significantly during the experimental period . Spectrofluorimetric and chromatographic data showed that the main evolution of oil concerns the degradation of n-alkanes and the removal of light aromatics . Biodegradation of hydrocarbons occurred at a measurable rate only during the warm seasons (average temperature 18 +/- 2 degrees C) causing after sixteen months the disappearance of more than 80% of the n-alkanes fraction independently of the pollution sediment level and the chemical treatment of the experimental plots . However, the biodegradation of n-alkanes proceeded during the first months, at different rates, inversely depending on oil content in the collected samples . The main limiting factor is dissolved oxygen according to the fact that spilled oil was located at 3-5 cm depth in a poorly oxygenated zone characterized by low redox potential . Nutrients were not a limiting factor probably due to domestic and agricultural inputs in this area . A marked bacterial growth was observed two weeks after the oil spill with a relative increase in hydrocarbon degrading bacteria with respect to total heterotrophs . Degradation rates, based on C14 n-hexadecane experiments, seem to follow the same way than specific bacterial counts (plate technique) . Specific bacteria are always high at the end of our 16 months' field experimentation . In the laboratory as well as in the field experiments, the same behaviour of untreated and chemically treated oil was observed in partially anaerobic sediment.

Crit Rev Ther Drug Carrier Syst, 1987, 3(3), 233 - 61
Nanoparticles in drug delivery; Douglas SJ et al.; Alkylcyanoacrylates can be polymerized in acidified aqueous media by a process of anionic polymerization . The small particles produced tend to be monodisperse and have sizes in the range of 20 to 3000 nm depending upon the polymerization conditions and the presence of additives in the form of surfactants and other stabilizers . The polyalkylcyanoacrylate nanoparticles so produced have been studied in recent years as a possible means of targeting drugs to specific sites in the body, with particular emphasis in cancer chemotherapy . The small colloidal carriers are biodegradable and drug substances can be incorporated normally by a process of surface adsorption . The review by Davis and others considers the formulation of nanoparticles, the important physicochemical variables such as pH, monomer concentration, added stabilizers, ionic strengths, etc., as well as the characteristics of the particle so created in terms of surface charge, particle size, and molecular weight . Monodisperse particles in the range of 20 to 3000 nm can be obtained . In addition, by the use of stabilizers such as dextran and its derivatives, which can be incorporated into the nanoparticle surface by a process of polymer grafting, it is possible to make nanoparticles with interesting surface characteristics and different surface charges (sign) . The stability of nanoparticles in vitro and their biodegradation in vivo are examined, and the possible formation of toxic products such as formaldehyde is highlighted . Alternative biodegradable acrylates are mentioned . Drugs can be incorporated into nanoparticles by either direct incorporation during the polymerization process or adsorption to preformed nanoparticles . The efficiency of the incorporation and the release characteristics of model compounds as well as anticancer drugs are discussed . Methods for examining these processes, including the determination of adsorption and desorption, kinetics, and isotherms, are mentioned . Selectivity in drug targeting can, in theory, be achieved by the attachment of some form of homing device, normally a monoclonal antibody or a lectin . Work in vitro and in vivo, where nanoparticles have been coated with monoclonal antibodies, is described . Finally, methods for the labeling of nanoparticles with gamma-emitting radionuclides are presented, and results obtained in animal species are given.

Proc Natl Acad Sci U S A, 1987 Jan, 84(2), 393 - 7
Covalent structure of biodegradative threonine dehydratase of Escherichia coli: homology with other dehydratases; Datta P et al.; The 987-base-pair coding region of the tdc gene of Escherichia coli K-12 encoding biodegradative threonine dehydratase {Tdc; L-threonine hydro-lyase (deaminating), EC 4.2.1.16}, previously cloned in this laboratory, was sequenced . The deduced polypeptide consists of 329 amino acid residues with a calculated Mr of 35,238 . Although the purified enzyme was shown to contain tryptophan, no tryptophan codon was found in the tdc reading frame . Incubation of purified Tdc with {14C}tryptophan revealed apparent "covalent" binding of tryptophan, indicating posttranslational modification of the enzyme . A heptapeptide, 54Thr-55Gly-56Ser-57Phe-58Lys-59Ile- 60Arg, was found to contain Lys-58, which binds pyridoxal phosphate coenzyme . A comparison of amino acid sequences between the Tdc polypeptide and the biosynthetic threonine dehydratases of yeast (encoded by ILV1) and E . coli (encoded by ilvA) and the E . coli D-serine dehydratase (DsdA, encoded by dsdA) revealed various extents of homology: five domains of the Tdc polypeptide were 63-93% homologous with the yeast enzyme, and three of these same regions were 80% homologous with the biosynthetic E . coli dehydratase; two different domains showed 67% and 83% homology with DsdA . In addition, two other sequences were highly conserved in all four proteins, one of which was shown to contain the conserved lysine residue that binds pyridoxal phosphate in the Tdc and DsdA polypeptides . These observations suggest that, despite their diverse origin and metabolic significance, these enzymes may have evolved from a common ancestral protein.

J Orthop Res, 1987, 5(1), 114 - 21
Porous hydroxyapatite as a bone graft substitute in diaphyseal defects: a histometric study; Holmes RE et al.; Porous hydroxyapatite (IP200), formed by conversion of the Poritidae porites exoskeleton, has pores averaging 230 microns and pore interconnections averaging 190 microns in diameter . In the distal radial diaphyses of 14 dogs, bilateral 7.5 X 20 mm cortical windows were created and fitted with 5 X 7.5 X 20 mm blocks of IP200 implants and iliac autografts . Both implanted and contralateral grafted radius specimens were retrieved at 3, 6, 12, 24, and 48 months . Unstained undecalcified sections were examined by microradiography and UV epi-illumination . Stained undecalcified sections were examined by light microscopy and quantitated by histometric methods . Implant specimens demonstrated good union and bone ingrowth at all time intervals . The implant specimens were composed of (mean +/- SE) 10.6% +/- 1.0% soft tissue, 51.2% +/- 1.3% bone, and 38.2% +/- 1.0% IP200 . The graft specimens showed good union with little apparent ingrowth at 3 months, followed by progressive appositional closure of cancellous spaces . The graft specimens contained 21.9% +/- 0.9% bone at 3 months with increases at each time interval to 73.1% +/- 8.7% at 48 months . The volume fraction and mean width of IP200 did not change with time, confirming the absence of implant biodegradation . The volume fraction and mean width of bone remained stable in the implant but increased in the graft specimens, corresponding to graft neocortex formation . It is concluded that implants initially filled in with bone while grafts initially replaced much of their spongiosa and subsequently filled in with bone . Histometry of untreated defects and measurement of mechanical properties are suggested for further study.

Experientia Suppl, 1987, 52, 573 - 80
Cadmium-zinc interactions in the Ehrlich cell: metallothionein and other sites; Petering DH et al.; Zinc and Cadmium metabolism in cultured Ehrlich cells has been studied . Under conditions of restriction of extracellular zinc by EDTA or chelex, zinc in basal Zn-metallothionein (Mt) is transferred from metallothionein to other sites with a rate constant of 0.35 hr-1 . Current studies indicate that the rate constant for biodegradation of Mt protein is 0.07-0.11 hr-1, implying that Zn leaves the protein faster than it is biodegraded . After a 30 minute exposure of cells to 17 ng atoms Cd/mg cell protein, Cd initially displaces Zn from Mt and binds to high molecular weight species . Cell proliferation is markedly slowed, although the cells remain viable . Over time Cd shifts into newly synthesized Mt . This protein is made with an apparent rate constant four times that for basal Zn-Mt . The product contains equal amounts of Cd and Zn . However, cell proliferation is not restored for many hours after Cd is sequestered in Mt.

Arkh Patol, 1987, 49(6), 3 - 10
{Mechanisms and role of collagen biodegradation in pathology}; Matskevichus ZK; Three stages in collagen biodegradation are considered: intracellular post-translational degradation of normal procollagen prior to its extracellular secretion; specific enzymatic cleavage of collagen fibrils in the extracellular space; and unspecific proteolysis of the cleaved despiralized molecular fragments . Enzymes involved in collagen breakdown are described . The importance of collagen biodegradation to morphogenesis and morphostasis is discussed, as are its disturbances in a number of pathological conditions.

Biochim Biophys Acta, 1986 Dec 10, 884(3), 517 - 9
Is chemiluminescence an index of hepatic lipoperoxidation accompanying chloroform anesthesia?
Cohen PJ, Chance B.
Hepatic lipoperoxidation by highly reactive metabolites produced during biodegradation of chloroform is believed to cause delayed hepatic necrosis . Chemiluminescence occurs during interaction of these metabolites with a lipid membrane . We have made continuous in vivo measurements of hepatic light output in the phenobarbital-induced rat breathing either air or chloroform vaporized in air . The data permitted direct estimation of the time course of chloroform-induced lipoperoxidation . These potentially toxic events began 15 min after initiation of anesthesia and continued for the duration of the study . Chemiluminescence did not occur with inhalation of isoflurane, an anesthetic undergoing minimal biodegradation.

Experientia, 1986 Dec 1, 42(11-12), 1192 - 7
Psychrophilic and psychrotrophic microorganisms; Gounot AM; Psychrophilic and psychrotrophic microorganisms have the ability to grow at 0 degree C . Psychrotrophic microorganisms have a maximum temperature for growth above 20 degrees C and are widespread in natural environments and in foods . Psychrophilic microorganisms have a maximum temperature for growth at 20 degrees C or below and are restricted to permanently cold habitats . This ability to grow at low temperature may be correlated with a lower temperature characteristic than that of the mesophiles, an increasing proportion of unsaturated fatty acids in the lipid phase of the cell membrane, which makes it more fluid, and a protein conformation functional at low temperature . The relatively low maximum temperature of growth for these microorganisms is often considered to be due to the thermolability of one or more essential cellular components, particularly enzymes, while some degradative activities are enhanced, resulting in an exhaustion of cell energy, a leakage of intracellular substances or complete lysis . Psychrotrophic microorganisms are well-known for their degradative activities in foods . Some are pathogenic or toxinogenic for man, animals or plants . However in natural microbial ecosystems psychrotrophic and psychrophilic microorganisms can play a large role in the biodegradation of organic matter during cold seasons.

Ecotoxicol Environ Saf, 1986 Oct, 12(2), 166 - 79
Kinetics of biodegradation of nitrilotriacetic acid (NTA) in an estuarine environment; Larson RJ et al.; The effects of salinity and dissolved organic carbon (DOC) on the kinetics of biodegradation of nitrilotriacetic acid (NTA) were studied in a Canadian estuary with a prior history of NTA exposure . Kinetic parameters for degradation of 14C-labeled NTA, maximum velocity (Vmax) and first-order rate constant (k1), were estimated by nonlinear regression models from velocity and time-course plots, respectively . The distribution of bacteria with NTA-degrading capability was also determined at various salinities and DOC levels by the 14C-most-probable-number (14C-MPN) technique . In general, NTA degradation was rapid in estuarine water over the range of salinities and DOC levels tested . Mean Vmax and k1 values (+/- standard deviation) across several sampling periods averaged 4753 +/- 2849 ng liter-1 hr-1 and 0.32 +/- 0.19 day-1, respectively . The estimated half-life for NTA degradation in estuarine water, based on the mean k1 value, was approximately 2 days . Degradation rates for NTA were relatively insensitive to changes in salinity or DOC values, and neither of these two parameters had significant effects on NTA degradation at the microbial community or individual cell levels . Based on 14C-MPN results, the distribution of estuarine bacteria capable of degrading NTA was broad and not related to salinity or DOC levels . The NTA degraders appeared to be indigenous members of the estuarine microbial community and not wastewater-associated microorganisms.

Appl Environ Microbiol, 1986 Oct, 52(4), 681 - 8
Extrapolation of biodegradation results to groundwater aquifers: reductive dehalogenation of aromatic compounds; Gibson SA et al.; The reductive biodegradation of a variety of haloaromatic substrates was monitored in samples from two sites within a shallow anoxic aquifer and was compared with freshwater sediment and sewage sludge . The metabolic capacity existing in methane-producing aquifer material was very similar to that in sediment in that three of four chlorobenzoates, five of seven chlorophenols, and one of two chlorophenoxyacetate herbicides were reductively dehalogenated in both types of incubations . The 2,4-dichlorophenoxyacetate was first converted to a dichlorophenol before dehalogenation occurred . Sewage sludge microorganisms dehalogenated four of seven chlorophenols tested and degraded both phenoxyacetate herbicides by first converting them to the corresponding chlorophenols, but the microorganisms did not transform the chlorobenzoates . In general, the same suite of initial metabolites were produced from a test substrate in all types of samples, as confirmed by cochromatography of the intermediates with authentic material . Aquifer microbiota from a sulfate-reducing site was unable to significantly degrade any of the haloaromatic substrates tested . Biological removal of the sulfate in samples from this site permitted dehalogenation of a model substrate, while stimulation of methanogenesis without removal of sulfate did not . These results demonstrate that dehalogenating microorganisms were present at this site but that their activity was at least partially inhibited by the high sulfate levels.

J Pharm Sci, 1986 Oct, 75(10), 962 - 7
Biodegradable microspheres . IV: Factors affecting the distribution and degradation of polyacryl starch microparticles; Laakso T et al.; Polyacryl starch microparticles have been suggested as lysosomotropic drug carriers . In this paper we report the study of the distribution and elimination of polyacryl starch microparticles after intravenous administration in mice . The half-life of the particles in the circulation is short (less than 5 min) and they are efficiently taken up by the reticuloendothelial (RES) system, mainly in the liver (50-90%) . The stability of the particles, as studied both in vitro (with serum and lysosome preparations) and in vivo (via the elimination from the liver), depends on two factors, the amount of initiator of the polymerization process (N,N,N',N'-tetramethylethylenediamine, TEMED) and the degree of derivatization of the starch . TEMED, used for the polymerization of the acryl groups forming the hydrocarbon chains, determines the number and the length of the cross-links between the starch molecules . The results indicate that large amounts of TEMED induce the formation of particles with many and short cross-links, which are easily degraded and dissolved in serum and more rapidly eliminated from the liver . The stability in serum can be improved by coadministration of soluble starch . Prolonged treatment of the starch with acrylic acid glycidyl ester leads to a high degree of derivatization and, consequently, to less degradable particles remaining in the lysosomes of the RES . The extent of biodegradation of the polyacryl starch particles could be anticipated from in vitro degradation of the monomers (acryloylated starch) with amyloglucosidase.

Ecotoxicol Environ Saf, 1986 Oct, 12(2), 127 - 40
Comparative kinetics study of the evolution of freshwater aquatic toxicity and biodegradability of linear and branched alkylbenzene sulfonates; Gard-Terech A et al.; Evolution of both primary biodegradability and acute toxicity to daphnia and zebra fish of a linear alkylbenzene sodium sulfonate (LAS) and a branched alkylbenzene sodium sulfonate (BAS) have been measured simultaneously . In six of eight experiments, LAS was biodegraded to 90% in 7 days and BAS to 70% in 7 days . In the two other experiments, both LAS and BAS have shown the same biodegradation speed and reached the same biodegradation level in 7 days: 45% in one experiment and 55% in the other . The composition of bacteria population and the level of cellular ATP of the inoculum play a decisive role in the biodegradation . These results confirm that it is essential to know the composition of bacteria population present in the inoculum as well as their biochemical characteristics to accurately interpret results of biodegradation tests . In the case of a rapid primary biodegradation of LAS and BAS, the acute toxicity of LAS remains three times as high as that of BAS for at least 24 hr toward daphnia and 48 hr toward zebra fish . Their acute toxicity to daphnia and zebra fish become equivalent only after 72 hr . When primary biodegradation of both products is slower, the acute toxicity of LAS remains higher than that of BAS for more than 7 days.

Am J Orthod Dentofacial Orthop, 1986 Sep, 90(3), 195 - 8
Biodegradation of the orthodontic bracket system; Maijer R et al.; Corrosion of the orthodontic appliance may occur in vivo with time . Electrochemical breakdown of corrosion-resistant high nickel and titanium wire can also occur . The use of recycled brackets could possibly accelerate the corrosion process . New and recycled brackets were evaluated in vitro in an artificial saliva system . The results indicated that different brands of new brackets have differences in corrosion behavior . In addition, recycling by the three commercial processes tested increased the liability of brackets to undergo corrosion . Superior behavior was noted for two types of bracket bases . Bracket corrosion may be assessed by a simple in vitro test.

Clin Sci (Lond), 1986 Aug, 71(2), 161 - 5
Circulating hyaluronate: concentration in different vascular beds in man; Bentsen KD et al.; The plasma concentration of hyaluronate (hyaluronic acid; HA) was measured in different vascular beds in order to determine regional kinetics of endogenous HA in fasting, supine subjects with normal (n = 6) or moderately decreased kidney function (n = 9) . In both groups hepatic venous HA was significantly below the value obtained in plasma from pulmonary artery, inferior vena cava, and renal veins (P less than 0.001), giving a net hepato-splanchnic extraction ratio of HA about 33% . The concentration of HA in renal veins was significantly below that of the pulmonary artery and inferior vena cava (P less than 0.05) . Average net renal extraction ratio of HA in normal kidneys was approximately 20% . Unilateral kidney function was assessed by 131I-hippuran renography, and the kidney with better function had a significantly higher extraction ratio when compared with the kidney with the lower function (P less than 0.025) . HA was inversely correlated to glomerular filtration rate (r = -0.59, P less than 0.02) . Assuming a plasma flow of 800 and 600 ml/min in normal liver and kidneys, respectively, the average normal plasma clearances of HA in these organs in the resting subject may be estimated to be 250 and 120 ml/min, respectively . The results indicate that the hepato-splanchnic region normally plays a major role in the biodegradation of endogenous circulating HA . The kidneys also eliminate the compound, presumably the low-molecular-weight fraction of the material . The results may explain abnormally high values of circulating HA in patients with diseases in these organs.

Appl Environ Microbiol, 1986 Aug, 52(2), 290 - 6
Rates of dissolution and biodegradation of water-insoluble organic compounds; Thomas JM et al.; We conducted a study of the relationship between the dissolution rates of organic compounds that are sparingly soluble in water and the biodegradation of these compounds by mixed cultures of bacteria . The rates of dissolution of naphthalene and 4-chlorobiphenyl were directly related to their surface areas . The bacteria caused a decline in the concentration of the soluble substrate . The rate of bacterial growth fell abruptly when 4-chlorobiphenyl or naphthalene was no longer detectable in solution . The population continued to increase in media with different surface areas of insoluble 4-chlorobiphenyl, but the final counts were higher in media in which the surface areas of the substrate were larger . The rates of dissolution of palmitic acid, octadecane, di(2-ethylhexyl) phthalate, and 1-naphthyl N-methylcarbamate were determined in the absence of microorganisms . A mixed culture of microorganisms mineralized palmitic acid, di(2-ethylhexyl) phthalate, and Sevin (1-naphthyl N-methylcarbamate) at a logarithmic rate, but octadecane mineralization was linear . The rates of mineralization at the end of the active phase of the biodegradation were lower than the rate of dissolution of palmitic acid but higher than the rate of dissolution of octadecane in the uninoculated medium . We suggest that spontaneous dissolution rates are only one of the factors that govern the rates of biodegradation.

Biochem Pharmacol, 1986 Jul 1, 35(13), 2221 - 7
Crystal structure of phlorizin and the iodothyronine deiodinase inhibitory activity of phloretin analogues; Auf'mkolk M et al.; Phloretin, a 7,8-dihydrochalcone of plant origin, and the high molecular weight (less than 15,000) polyphloretinphosphate (PPP) polymers are potent inhibitors of iodothyronine monodeiodinase activity from rat liver microsomal preparations, whereas phlorizin, the 2'-O-glucoside of phloretin, is inactive . The polymers, differing in degree of phosphorylation-dependent polymerization, exhibited a concentration-dependent, and ultimately complete, inhibition of deiodinase activity with an IC50 between 0.2 and 0.5 micrograms PPP/ml . Phloretin inhibition, on the other hand, was cofactor (DTE) competitive, with a Ki = 0.75 microM . 2',4',6',3,4- Pentahydroxychalcone, which has a substitution pattern in the A-ring identical to that of phloretin, was the only active inhibitor (IC50 = 8 microM) among several derivatives tested . The phloretin biodegradation products, phloretic acid and phloroglucinol, and its biosynthetic precursors, monomeric cinnamic acid and cinnamic acid derivatives, were inactive in concentrations up to 100 microM . The X-ray crystal structure analysis of phlorizin dihydrate showed that the molecule is planar and fully extended, similar to the conformation observed in chalcone structures that are characterized by an alpha, beta-unsaturated bond between phenol rings . Comparison of the planar phlorizin crystal structure with a skewed or antiskewed thyroid hormone conformation revealed that the beta-D-glucose moiety does not share any of the thyroid hormone's conformational space, and that the best structural homology is found with the antiskewed conformation of 3',5',3-triiodothyronine, the natural deiodinase substrate that also inhibits further deiodination.

Microbiol Sci, 1986 Jul, 3(7), 197 - 200
Controlled marine ecosystems in the investigation of oil biodegradation at sea; Bertrand JC; In the marine environment, petroleum is subject to the action of physico-chemical weathering and microbial biodegradation . Experimental controlled ecosystems have provided essential information about the fate of petroleum at sea.

J Cell Physiol, 1986 Jul, 128(1), 27 - 32
Age dependency of the metabolic conversion of polyamines into amino acids in IMR-90 human embryonic lung diploid fibroblasts; Chen KY et al.; When radioactive polyamines (putrescine or spermidine) were incubated with mammalian cells in tissue culture, the radioactivity was incorporated into cellular proteins via two different metabolic pathways; one is metabolic labeling of an 18,000-dalton protein via hypusine formation, and the other is general protein synthesis employing radioactive amino acids derived from biodegradation of polyamines via GABA shunt and Krebs cycle . Aminoguanidine, a potent inhibitor of diamine oxidase, blocked the metabolic conversion of polyamines to amino acids but had no effect on the metabolic labeling of the 18,000-dalton protein . We have investigated these two polyamine-associated biochemical events in IMR-90 human diploid fibroblasts as a function of their population doubling level (PDL) . We found that (1) the metabolic labeling of the 18,000-dalton protein was about two-fold greater in young cells (PDL = 22) than that in old cells (PDL = 48), and (2) the metabolic labeling of other cellular proteins, employing amino acids derived from putrescine via polyamine catabolic pathway, was more than six-fold greater in the old cells (PDL = 48) than in the young cells (PDL = 22) . Since the rate of protein synthesis was about 1.4-fold higher in the young cells as compared to the old cells, our data indicated that the activity of catabolic conversion of putrescine (or spermidine) to amino acids in old IMR-90 cells was about eight-fold greater than that in young cells . This remarkable increase of polyamine catabolism and the slight decrease of metabolic labeling of the 18,000-dalton protein were also observed in cell strains derived from patients with premature aging disease.

J Immunol, 1986 Jul 1, 137(1), 296 - 301
Enteral and systemic release of leukotrienes during anaphylaxis of Nippostrongylus brasiliensis-primed rats; Moqbel R et al.; Rats with acquired immunity to the intestinal nematode Nippostrongylus brasiliensis develop anaphylaxis after i.v . challenge with an extract of worm antigen, with the small intestine being the primary shock organ . In the present study we have shown that these events were associated with significant elevations in intestinal and plasma concentrations of leukotrienes LTB4 and LTC4 . The changes were observed in immune rats over 10-, 30-, and 60-min intervals after antigen challenge but were absent in control animals . These lipid mediators were identified both in the perfusate of the gut lumen, which contained large quantities of mucus, and in homogenates of intestinal tissue . In addition, significant elevations in the concentrations of plasma LTB4 and LTC4 were detected in immune challenged rats but not in controls . Leukotrienes were identified by radioimmunoassay and validated by reverse-phase high-performance liquid chromatography (RP-HPLC) . RP-HPLC analysis of SRS-A leukotrienes in immune challenged rats indicated that LTC4 was the predominant sulfidopeptide leukotriene at 10 min, with almost complete biodegradation to LTD4 and LTE4 within 30 min . Infected rats also had significant increases in the numbers of intestinal mucosal mast cells (MMC) and eosinophils . Evidence of MMC activation during anaphylaxis was obtained by showing significant elevations of intestinal and systemic concentrations of their exclusive serine enzyme, rat mast cell proteinase II (RMCPII) . Thus, the release of substantial amounts of leukotrienes in the gut and plasma of N . brasiliensis-primed rats after interaction with worm antigens suggests that these potent mediators may play an important role in allergic-type hypersensitivity known to occur during immune reactions against parasitic helminths.

Appl Environ Microbiol, 1986 Jun, 51(6), 1153 - 60
Two approaches to modeling kinetics of biodegradation by growing cells and application of a two-compartment model for mineralization kinetics in sewage; Simkins S et al.; The patterns of microbial mineralization of 0.3 to 30 ng of glucose, benzoate, and phenol per ml of sewage collected in late fall and winter were analyzed with the integrated Monod equation and a model in which growth of active organisms occurs at the expense of organic compounds other than the test substrate . Either model could be closely fit by nonlinear regression to the data from individual tests with one concentration of substrate added to one dilution of sewage . However, neither model accounted satisfactorily for differences in patterns of mineralization resulting from differences in substrate concentration and cell density between different tests . It is suggested that both the added substrates and other organics present in sewage contributed to the growth of the active organisms . The mineralization of glucose in sewage collected in summer was better described by a two-compartment model than by any other model tested.

Metabolism, 1986 Jun, 35(6), 542 - 6
Endogenous pancreatic polypeptide in different vascular beds: relationship to release and degradation in subjects with normal and decreased kidney function; Henriksen JH et al.; The plasma concentration of pancreatic polypeptide (PP-like immunoreactivity) was measured in different vascular beds in order to determine regional kinetics of endogenous PP in fasting, supine subjects with normal or moderately decreased kidney function . Patients with kidney disease (n = 10) had a significantly higher level of circulating PP than controls (n = 10): median PP = 52 (range 21 to 352) v 20 (6 to 143) pmol/L, respectively (P less than 0.02) . Circulating PP was inversely correlated to 51Cr-EDTA plasma clearance (r = -0.57, P less than 0.02, n = 14) and directly correlated to serum creatinine concentration (r = 0.70, P less than 0.01) . Hepatic venous PP was significantly higher than systemic PP in both controls and patients with kidney disease (P less than 0.001, n = 15) . The values were positively correlated (r = 0.98, P less than 0.001; slope = 1.37 +/- 0.05, P less than 0.001), indicating a progressively increasing rate of PP secretion in subjects with raised circulating PP . No statistically significant difference could be detected between systemic and renal venous PP or across the lung, left adrenal gland, or lower limb . Assuming steady state between secretion and biodegradation, the metabolic clearance rate of the peptide was estimated to be approximately 600 to 800 mL/min in controls and slightly below this value in patients with nephropathy . These results suggest that the raised circulating PP found in patients with decreased kidney function is due to both increased secretion and decreased degradation.(ABSTRACT TRUNCATED AT 250 WORDS)

Acta Ophthalmol (Copenh), 1986 Jun, 64(3), 338 - 43
Dislocated intraocular lens after biodegradation of fixation loops . A case report; Krause U et al.; A boy aged 3 years had a Worst Medallion intraocular lens with loops made of nylon 6 implanted in his right eye after aspiration of traumatic cataract . Post-operatively, the eye was irritated and showed increased tendency to secondary membrane formation . The patient was lost to follow-up 3 months post-operatively . He returned 5 years later because of 4 days of pain and redness in his right eye . On examination, the optic part of the intraocular lens was seen to lie free in the anterior chamber . The loops were broken near their insertions in the lens body . The distal ends of the broken loops could not be detected in the pupillary region . No traces of the iris fixation suture were to be seen . The lens was removed and subjected to scanning electron microscopy which revealed extensive biodegradative changes in the 3 loop stumps, the 4th being totally dissolved . The young age of the patient and the chronic inflammation may have had an accelerating effect on the nylon degradation . We conclude that children with eyes implanted with nylon-loop lenses should stay under regular ophthalmological control.

Arch Latinoam Nutr, 1986 Jun, 36(2), 345 - 50
{Effect of the inoculation of the comestible fungus Pleurotus ostreatus on the chemical composition and digestibility of barley straw}; Ortega Cerrilla ME et al.; The purpose of the present study was to determine whether incubation of the edible mushroom Pleurotus ostreatus in barley straw for 45 or 60 days, proved to be a means of increasing the nutritive value and digestibility of the straw for ruminant animals . In this respect, the following determinations were performed in untreated barley straw (control), and in incubated barley straw with the mushroom strain mentioned previously, for 45 or 60 days: pH, moisture, crude protein, ash, hemicellulose, cellulose, lignin, gross energy and in vitro digestibility of the dry matter . Results showed that crude protein percentage remained constant (p less than or equal to 0.05) in all treatments (means 2.67%), increasing the ash content of the straw incubated for 60 days . The hemicellulose and cellulose percentages diminished significantly (p less than or equal to 0.05) in the straw incubated for 45 or 60 days (16.74, 32.24, 17.43, 32.41% respectively) than in the control straw (24.54, 40.15%) . The lignin percentages increased, although not significantly in the straw incubated for 45 or 60 days with respect to the control straw (8.36; 9.10, 9.06%, respectively) . Energy values were lower for the straw incubated 45 or 60 days (2.70; 2.74 Kcal/g) than for the control straw (2.80 Kcal/g), without difference in the in vitro dry matter digestibility by incubating the straw for 45 or 60 days with Pleurotus ostreatus and the control (56.04; 52.65; 53.06% respectively) . It is concluded that the Pleurotus ostreatus strain used in this study was unable to delignify the straw, because of its lack of fenoloxidases, enzymes which are necessary for lignin biodegradation.(ABSTRACT TRUNCATED AT 250 WORDS)

Eur J Clin Invest, 1986 Jun, 16(3), 211 - 6
Circulating endogenous vasoactive intestinal polypeptide (VIP) in patients with uraemia and liver cirrhosis; Henriksen JH et al.; The concentration of vasoactive intestinal polypeptide (VIP) in peripheral venous plasma was median 6.0 pmol l-1 (range 0-20) in 112 normal subjects . In fifty-three patients with decreased kidney function plasma VIP was significantly increased (median 15.0 pmol l-1, range 0.5-70, P less than 0.0001) and positively correlated to serum creatinine concentration (r = 0.51, P less than 0.001) . In 133 patients with liver cirrhosis peripheral venous VIP was slightly elevated (median 7.0 pmol l-1 range 0-86, P less than 0.01) . Samples obtained during a central venous catheterization showed significant renal extraction of circulating VIP in control subjects (median extraction fraction 23%, P less than 0.05, n = 6) and in patients with cirrhosis (median 60%, P less than 0.02, n = 8), but not in uraemic patients (median 0%, NS n = 5) . In control subjects and patients with cirrhosis the concentration of VIP in the hepatic vein was significantly below that of systemic plasma (-42%, P less than 0.05, n = 6 and -45%, P less than 0.01, n = 10, respectively) . On the contrary, in uraemic patients hepatic venous VIP was almost similar to systemic VIP (-4%, NS, n = 7) . The results indicate that in normal subjects and patients with cirrhosis both the liver and kidneys are involved in the biodegradation of VIP . The elevated level of circulating VIP in uraemic patients may in part be due to decreased renal and hepatic biodegradation but increased neuronal release of VIP, especially in the splanchnic system, may also contribute to the increased plasma VIP in this condition.

Appl Environ Microbiol, 1986 May, 51(5), 891 - 7
Kinetics of mineralization of phenols in lake water; Jones SH et al.; The kinetics of mineralization of phenol and p-nitrophenol in lake water was determined at concentrations from 200 pg/ml to 5 micrograms/ml . The mineralization data were fit by nonlinear regression to equations for 14 kinetic models that describe patterns of biodegradation by nongrowing cells or by microorganisms growing on either the test chemical or other organic substrates . The kinetics od mineralization of phenol in water samples collected in July was best described by first-order models for 0.5 ng of phenol per ml; by Monod-without-growth, logistic, and logarithmic models for 1.0 and 2.0 ng/ml and 5.0 ng/ml to 1.0 micrograms/ml, respectively, if it is assumed that the mineralizing population uses phenol as the sole carbon source for growth; by models (for phenol at concentrations of 2.0 ng/ml to 1.0 micrograms/ml) that assume that the phenol-mineralizing populations do not grow or grow logarithmically or logistically on uncharacterized carbon compounds but metabolize the phenol when present at levels below and above Km, respectively, for that compound; and by a logarithmic model at 5.0 micrograms/ml . Under the test conditions, usually less than 10% of the phenol C that was metabolized was incorporated into microbial cells or retained by other particulate material in the water at substrate concentrations of 10 ng/ml or less, and the percentage increased at higher substrate concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Appl Environ Microbiol, 1986 May, 51(5), 950 - 5
Effects of dissolved oxygen concentration on biodegradation of 2,4-dichlorophenoxyacetic acid; Shaler TA et al.; Batch experiments were conducted to examine the effects of dissolved oxygen concentration on the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) by an enrichment culture of 2,4-D-utilizing bacteria . A modified Monod equation was found to describe the relationship between the specific growth rate and the concentrations of both the organic substrate and dissolved oxygen . Values for the maximum specific growth rate, yield, and Monod coefficient for growth on 2,4-D were 0.09 h-1, 0.14 g/g, and 0.6 mg/liter, respectively . The half-saturation constant for dissolved oxygen was estimated to be 1.2 mg/liter . These results suggest that dissolved oxygen concentrations below 1 mg/liter may be rate limiting for the biodegradation of chlorinated aromatic compounds such as 2,4-D, which have a requirement for molecular oxygen as a cosubstrate for metabolism.

J Gen Microbiol, 1986 Apr, 132 ( Pt 4), 963 - 72
Metabolite production during the biodegradation of the surfactant sodium dodecyltriethoxy sulphate under mixed-culture die-away conditions; Griffiths ET et al.; Sodium dodecyltriethoxy sulphate (SDTES), either pure or as a component of commercial surfactant mixtures, underwent rapid primary biodegradation by mixed bacterial cultures in OECD screen and river-water die-away tests . Inoculation of {35S}SDTES-containing solutions with OECD screen test media acclimatized to surfactants or their degradation products led to production of various 35S-labelled glycol sulphates and their oxidation products, all known to occur during degradation of {35S}SDTES by pure bacterial isolates . Triethylene glycol monosulphate was the major catabolite together with smaller amounts of di- and monoethylene glycol monosulphates implying, by analogy with pure cultures, that ether-cleavage was the major primary biodegradation step . The oxidation product (carboxylate derivative) of each glycol sulphate was also detected together with metabolites tentatively identified as omega-/beta-oxidation products of the dodecyl chain . Relatively little SO2-4 was liberated directly from SDTES but mixed cultures derived from sewage could metabolize the sulphated glycols to SO2-4 . The environmental relevance of these degradation routes was established by following metabolite production from {35S}SDTES in full-scale river-water die-away tests . Triethylene glycol sulphate was formed first, then rapidly oxidized to acetic acid 2-(diethoxy sulphate) which persisted as the major metabolite for 2-3 weeks . Small amounts of sulphated derivatives of di- and monoethylene glycols were also detected during the same period . Very little SO2-4 was formed directly from SDTES but large amounts accompanied the eventual disappearance of glycol sulphate derivatives . None of the 35S-labelled organic metabolites was persistent and, whenever {35S}SDTES was a component of a commercial mixture, all ester sulphate was completely mineralized to 35SO4(2-) within 28 d.

J Gen Microbiol, 1986 Apr, 132 ( Pt 4), 953 - 61
A comparative study of the biodegradation of the surfactant sodium dodecyltriethoxy sulphate by four detergent-degrading bacteria; Hales SG et al.; The 35S-labelled metabolites produced during biodegradation of sodium dodecyltriethoxy {35S}sulphate (SDTES) by four bacterial isolates were identified and quantified . All four isolates used ether-cleavage as the predominant primary degradation pathway . In two of the organisms, the etherase system (responsible for approx . 60-70% of primary biodegradation) liberated mono-, di- and triethylene glycol monosulphates in substantial proportions, the last two esters undergoing some further oxidation to acetic acid 2-(ethoxy sulphate) and acetic acid 2-(diethoxy sulphate), respectively . For these isolates, liberation of SO4(2-) directly from SDTES was also significant (30-40%) and the organisms were shown to contain alkyl sulphatases active towards SDTES . For the remaining two isolates, etherase action was even more important (responsible for greater than 80% of primary biodegradation) and was restricted almost totally to the alkyl-ether bond to generate mainly triethylene glycol sulphate, some of which was further oxidized . Very small amounts of diethylene glycol monosulphate were also produced, but its mono-homologue, and the oxidation products of both these esters, were absent . Small amounts of inorganic sulphate (approx . 10%) were liberated by these isolates and one of them also produced compounds tentatively identified as intermediates of omega-/beta-oxidation.

J Biomed Mater Res, 1986 Apr, 20(4), 417 - 31
Retrieval and analysis of a clinical total artificial heart; Coleman DL et al.; Examination by light microscopy, scanning electron microscopy (SEM), and x-ray microanalysis of a clinical total artificial heart (TAH) implanted for 112 days revealed no evidence of calcification, pannus, or vegetative thrombus . A macroscopic thrombus was seen along the suture line in the right atrium but did not obstruct blood flow or valve function . Microscopic thrombi (less than 0.1 mm) and evidence of microemboli were observed on the pumping diaphragm using SEM . Characterization of selected polyetherurethane (PEU) samples from the pumping bladders and housing by Curie-point pyrolysis mass spectrometry (Py-MS) revealed unexpected differences between postmortem retrieved ventricles . Although the origin of these differences could be traced back to batch-to-batch variations in the original PEU material (Biomer), the precise nature of the observed differences in chemical structure and/or composition is still unknown . Numerical comparison between pyrolysis mass spectra from PEU samples exposed to blood or tissue and unexposed samples from the same ventricles did not detect evidence of biodegradation . Continual improvements in fabrication and quality control should minimize surface imperfections and ensure polymer reproducibility; however, existing materials and design parameters appear to be adequate for continued clinical implantation.

Vet Hum Toxicol, 1986 Apr, 28(2), 127 - 43
Fate of synthetic organic chemicals in soil-groundwater systems; Pancorbo OC et al.; Land disposal of municipal, industrial and agricultural wastes often leads to soil and groundwater contamination with synthetic organic chemicals . In this review, the fate of such organics in soils and the subsurface environment is discussed . In particular, the biodegradation of organic compounds in soils and the subsurface region, as well as the sorption of these compounds to soils is emphasized . Due to the disastrous impact of groundwater contamination on a community and the great cost of restoring a contaminated aquifer, a case is made for concentrating future efforts on isolating potential sources of groundwater contamination and instituting appropriate control measures.

Appl Environ Microbiol, 1986 Apr, 51(4), 720 - 4
Biodegradation of chlorinated ethenes by a methane-utilizing mixed culture; Fogel MM et al.; Chlorinated ethenes are toxic substances which are widely distributed groundwater contaminants and are persistent in the subsurface environment . Reports on the biodegradation of these compounds under anaerobic conditions which might occur naturally in groundwater show that these substances degrade very slowly, if at all . Previous attempts to degrade chlorinated ethenes aerobically have produced conflicting results . A mixed culture containing methane-utilizing bacteria was obtained by methane enrichment of a sediment sample . Biodegradation experiments carried out in sealed culture bottles with radioactively labeled trichloroethylene (TCE) showed that approximately half of the radioactive carbon had been converted to 14CO2 and bacterial biomass . In addition to TCE, vinyl chloride and vinylidene chloride could be degraded to products which are not volatile chlorinated substances and are therefore likely to be further degraded to CO2 . Two other chlorinated ethenes, cis and trans-1,2-dichloroethylene, were shown to degrade to chlorinated products, which appeared to degrade further . A sixth chlorinated ethene, tetrachloroethylene, was not degraded by the methane-utilizing culture under these conditions . The biodegradation of TCE was inhibited by acetylene, a specific inhibitor of methane oxidation by methanotrophs . This observation supported the hypothesis that a methanotroph is responsible for the observed biodegradations.

Scand J Gastroenterol, 1986 Apr, 21(3), 300 - 4
Does liver-intestine significantly degrade circulating endogenous substance P in man?
Henriksen JH, Schaffalitzky de Muckadell OB, Bulow JB.
Elevated concentrations of circulating substance P in patients with liver insufficiency have been ascribed to decreased hepatic degradation . To establish a possible biodegradation of the peptide in liver-intestine and kidneys, the concentration of endogenous immunoreactive substance P was determined in various vascular beds during a right-sided catheterization in 13 subjects without liver insufficiency . All subjects had normal values of circulating substance P, and no significant difference was found between systemic plasma and hepatic venous or renal venous concentrations of substance P . The results indicate that degradation of circulating endogenous substance P in man is not confined to liver-intestine or kidney but may take place in many tissues.

Environ Health Perspect, 1986 Mar, 65, 337 - 40
Environmental fate and aquatic toxicology studies on phthalate esters; Group EF Jr; A comprehensive environmental fate and effects testing program, sponsored by the Chemical Manufacturers Association (CMA) Phthalate Esters Program Panel, has been completed . Based on the results, a preliminary safety assessment has shown that all of the 14 commercially important phthalates tested have sufficiently high safety factors to demonstrate low potential for adverse environmental effects . This program comprised acute toxicity studies on nine representative species of aquatic life, chronic reproduction studies on Daphnia magna, biodegradation (fate) testing, and physicochemical property (mobility) determinations on 14 phthalate esters . The objectives of this program were to determine for each test compound: The concentration at which effects on aquatic life might occur, the potential for bioconcentration in aquatic life, and the relative persistence in the environment . These data would provide the basis for an environmental safety assessment and would identify potential effects that might require further investigation . A total of 195 individual studies were carried out . Tests on a wide variety of aquatic organisms representing different food chain levels in both fresh and salt water environments showed that no single test species was unusually sensitive to the test materials . The higher molecular weight (longer side-chain) phthalates exhibited no toxic effects up to their limits of water solubility in the test systems . Even though the lower molecular weight, more water-soluble phthalates produced toxic effects below their limits of water solubility, no product exhibited unusually severe effects of concern.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomaterials, 1986 Mar, 7(2), 144 - 6
A comparative study of different beta-whitlockite ceramics in rabbit cortical bone with regard to their biodegradation behaviour; Klein CP et al.; Different beta-whitlockite ceramic cylinders of standard size were implanted in the tibiae of rabbits to study the influence of micropores and chemistry on the biodegradation rate . The materials were evaluated by radiography and light microscopy . Surface chemistry was varied by the addition of impurities, while different applied pressures before sintering and different sintering temperatures gave rise to different micropores . Both factors influenced the biodegradation rate.

Ann Otol Rhinol Laryngol Suppl, 1986 Mar-Apr, 123, 1 - 5
Hydroxyapatite ceramic as middle ear implant material: animal experimental results; Grote JJ et al.; Hydroxyapatite is the main constituent of the mineral matrix of bone . The behavior of porous and dense hydroxyapatite ceramic implants was studied in normal rat middle ears, after induced infection, and in an in vitro assay by light and electron microscopic techniques . All implants were integrated into the middle ears without signs of extrusion, and their mucosal coverings did not appear to differ fundamentally from those of normal ears . The porous hydroxyapatite became filled with fibrous tissue and bone that showed normal morphology, and there was direct bonding of the bone to the implants . Minor biodegradation was established for the porous implants . Hydroxyapatite did not affect cultured middle ear mucosa significantly in vitro . Induced infection failed to show any adverse effect on the behavior of the implants . These observations suggest that hydroxyapatite is very useful for reconstructive ear surgery.

Orthopade, 1986 Feb, 15(1), 30 - 5
{Significance of synthetic calcium phosphate ceramics as a bone replacement material}; Eitenmuller J; With reference to the chemical and crystallographic differences, the line is drawn against bone substitute material produced from biological material . Extensive animal experiments demonstrated the good healing properties when using calcium phosphate ceramics in bony defects . In the long term, there was more new bone formed after filling up the defect with calcium phosphate ceramics than when using autologous bone grafts . Clinically, there is an indication for using this material to fill up bone cysts and defects if there is enough time for biodegradation; in other cases, a mixture using an autologous spongoid graft is necessary.

Ecotoxicol Environ Saf, 1986 Feb, 11(1), 112 - 25
Aerobic and anaerobic biodegradation of nitrilotriacetate in subsurface soils; Ward TE; Studies were conducted to characterize mineralization of nitrilotriacetate (NTA) in subsurface soils under aerobic and anaerobic conditions . Chemical (redox indicator, resazurin) and biological (dentrification) markers were used as indicators of anaerobic conditions in the test system . The indigenous microflora in subsurface soils previously exposed to septage containing NTA were able to rapidly mineralize NTA under aerobic and anaerobic conditions . The half-lives (t1/2) of mineralization for NTA in aerobic soils ranged from 87 to 160 hr . Biodegradation of NTA under anaerobic conditions where NO3- indicates that a mechanism exists for the anaerobic biodegradation of this substrate . NTA biodegradation can occur readily in the absence of molecular oxygen and the NTA-monooxygenase which are required for the aerobic mineralization of this substrate . These results provide the first evidence that the indigenous microflora in subsurface soils of septic tank tile fields can rapidly degrade NTA under anaerobic conditions.

Appl Environ Microbiol, 1986 Feb, 51(2), 316 - 22
Biodegradation of tert-butylphenyl diphenyl phosphate; Heitkamp MA et al.; The biodegradation of tert-butylphenyl diphenyl phosphate (BPDP) was examined in microcosms containing sediment and water from five different ecosystems as part of our studies to elucidate the environmental fate of phosphate ester flame retardants . Biodegradation of {14C}BPDP was monitored in the environmental microcosms by measuring the evolution of 14CO2 . Over 37% of BPDP was mineralized after 8 weeks in microcosms from an ecosystem which had chronic exposure to agricultural chemicals . In contrast, only 1.7% of BPDP was degraded to 14CO2 in samples collected from a noncontaminated site . The exposure concentration of BPDP affected the percentage which was degraded to 14CO2 in microcosms from the two most active ecosystems . Mineralization was highest at a concentration of 0.1 mg of BPDP and was inhibited with 10- and 100-fold higher concentrations of BPDP in these microcosms . Indigenous heterotrophic and BPDP-utilizing microbial populations and phosphoesterase enzyme activities were highest in sediments which had the highest biodegradation of BPDP . We observed adaptive increases in both microbial populations and phosphoesterase enzymes in some sediments acclimated to BPDP . Chemical analyses of the residues in the microcosms indicated undegraded BPDP and minor amounts of phenol, tert-butylphenol, diphenyl phosphate, and triphenyl phosphate as biodegradation products . These data suggest that the microbial degradation of BPDP results from at least three catabolic processes and is highest when low concentrations of BPDP are exposed to sediment microorganisms of eutrophic ecosystems which have high phosphotri- and diesterase activities and previous exposure to anthropogenic chemicals.

Doc Ophthalmol, 1986 Jan 15, 61(3-4), 303 - 12
Mechanical and biochemical effects of man-made fibres and metals in the human eye, a SEM-study; Jongebloed WL et al.; Prolene, perlon, supramid and titanium, either used as sutures, 'Strampelli' sutures or artificial lens loops, were compared after remaining in the human eye for at least one year . For comparison, non-implanted samples of each of the materials were used as blanks . Prolene and Perlon in particular showed severe biodegradation after a given period; Supramid showed much less degradation of its surface . Titanium showed a rather rough outer surface (even in the non-implanted samples), particularly as bends in the lens loop, which facilitated the adherence of cells, fibres and microorganisms.

Surgery, 1986 Jan, 99(1), 45 - 52
Compliance and biodegradation of vascular grafts stimulate the regeneration of elastic laminae in neoarterial tissue: an experimental study in rats; van der Lei B et al.; Microporous vascular grafts that are compliant and biodegradable can function as scaffolds for the regeneration of the arterial wall in small-caliber arteries . The purpose of this study was to determine the specific influence of both compliance and biodegradation of microporous vascular grafts on this regeneration, especially on the regeneration of elastic laminae . Therefore we implanted three different types of microporous vascular grafts into the abdominal aorta of rats . These grafts were (I) compliant, biodegradable (group I; n = 6), (II) compliant, biostable (group II; n = 8), and (III) noncompliant, biodegradable (group III; n = 8) . Six weeks after implantation the implants were evaluated by means of light microscopy and electron microscopy . The compliance of the implants, as indicated by arterial pulsations, was well maintained in group I but not in group II . In all groups a neomedia had regenerated, composed of smooth muscle cells that were predominantly longitudinally arranged . Elastic laminae were present almost throughout the neomedia in group I, restricted to the luminal layers of the neomedia in group II, and totally absent in the neomedia of group III . These results demonstrate that both compliance and biodegradation stimulate the regeneration of elastic laminae in neoarterial tissue . Because of the compliance of microporous vascular grafts, smooth muscle cells are mechanically stimulated by the arterial pulsations to produce elastin arranged in laminae . Because of the biodegradation of these grafts, compliance is maintained, which therefore favors the regeneration of elastic laminae.

J Vasc Surg, 1986 Jan, 3(1), 146 - 54
Pathologic features of surgically excised human umbilical vein grafts; Guidoin R et al.; This article describes the pathologic changes in 31 human umbilical vein grafts excised from 23 patients after implantations ranging from 24 hours to 5 years . Gross morphologic examination, light microscopy, and scanning electron microscopy demonstrated that the umbilical vein grafts appeared to be fragile and easily delaminated . Bacteremic colonization on the luminal surface was present in the grafts removed because of infections but in two instances had extended into the wall . The presence of lipid on the surface and in the subintimal layer was observed in five grafts, three of which had been implanted for less than 1 month . We concluded that human umbilical vein grafts pathologically exhibit fragility, biodegradation, lipid accumulation, and bacterial colonization in infected cases, and these characteristics may adversely affect the durability and long-term success of the prosthesis.

Can J Microbiol, 1986 Jan, 32(1), 38 - 46
Response of the microflora in outdoor experimental streams to pentachlorophenol: environmental factors; Pignatello JJ et al.; The 2nd year of a 2-year study of the fate of pentachlorophenol in outdoor artificial streams focused on details of microbial degradation by a combination of in situ and laboratory measurements . Replicate streams were dosed continuously at pentachlorophenol concentrations of 0, 48, and 144 micrograms/L, respectively, for an 88-d period during the summer of 1983 . Pentachlorophenol was degraded both aerobically and anaerobically . Aerobic degradation was more rapid than anaerobic degradation . Mineralization of pentachlorophenol was concommitant with pentachlorophenol disappearance under aerobic conditions, but lagged behind loss of the parent molecule under anaerobic conditions . Biodegradation in the streams, or in specific stream compartments such as the sediment or water column, was characterized by an adaptation period (3-5 weeks for the stream as a whole, and reproducible from the previous year), which was inversely dependent on the concentration of pentachlorophenol and microbial biomass . The adaptation in the streams could be attributed to the time necessary for selective enrichment of an initially low population of pentachlorophenol degraders on surface compartments . The extent of biodegradation in the streams (percent loss of initial concentration of pentachlorophenol) increased with increasing pentachlorophenol input, which was explicable by an increase in the pentachlorophenol degrader population with increasing pentachlorophenol concentration . The sediment zone most significant to overall pentachlorophenol biodegradation was the top 0.5- to 1-cm layer as shown by pentachlorophenol migration rates and depth profiles of degrader density within the sediment . Pentachlorophenol profiles in sediment cores taken during and after the adaptation period for degradation showed that diffusion of pentachlorophenol into the sediment was rate limiting to degradation in this compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

IARC Sci Publ, 1986, (77), 53 - 9
Assessment of the persistence of hexachlorobenzene in the ecosphere; Mansour M et al.; Various degradation tests were carried out to assess the persistence of hexachlorobenzene (HCB) in the ecosphere . HCB was irradiated with light of various wave-lengths in organic solvents and in water, partly after addition of H2O2 or metal oxides . Photolysis to various dehalogenated products occurred at different rates, depending on concentration and irradiation time; HCB adsorbed on a silica gel was mineralized by light to CO2 . A negligible amount of 14C-labelled HCB was mineralized to 14CO2 in various biodegradation tests . In an outdoor lysimeter experiment, 14C residues were found in all parts of wheat plants grown from seeds treated with 14C-HCB . Besides the parent compound and bound residues in plants and soil, very small amounts of soluble polar metabolites were present in the plants; the main product of this group, isolated from roots, was conjugated pentachlorothiophenol . Wheat grown in soil with 14C-HCB residues contained unchanged HCB and bound residues.

J Arthroplasty, 1986, 1(2), 143 - 7
Properties of biomaterials; Lemons JE et al.; Metallic biomaterials, including iron-, cobalt-, and titanium-based systems, have a long history of applications for surgical implant devices . The mechanical properties of these alloys (modulus, strength, and ductility) have been used to make devices to replace skeletal structures with long-term in vivo stabilities . In addition, the passive surface oxide layers have provided chemical inertness within biologic environments . Recent trends to provide porous metallic conditions for biologic ingrowth and fixation have introduced questions with regard to the relative strength and biodegradation properties . Some biomaterial strengths have been reduced to magnitudes less than 50% of the nonporous alloys, which emphasizes the criticality of design . Surface area increases of 3-10 times has emphasized biocorrosion magnitudes, the elements released to the tissues, and the biologic consequences of these products . This article provides a brief review of these issues with emphasis on mechanical-biomechanical and chemical-biochemical properties of metallic alloys.

J Basic Microbiol, 1986, 26(9), 551 - 67
Construction of bacterial strains with novel degradative capabilities for chloroaromatics; Reineke W; Biodegradation of most naturally occurring compounds is relatively fast, since microorganisms have evolved appropriate enzyme systems . However, biodegradation is less likely in the case of man-made compounds like haloaromatics, which have structural features rarely or never encountered in natural products . One strategy to develop new metabolic activities for novel compounds by strains of microorganisms is by the alteration of their existing genetic information . The present paper summarizes results of studies where the degradation capabilities of bacteria were expanded by genetic material from external sources either by natural exchange or by cloning procedures.

Dent Clin North Am, 1986 Jan, 30(1), 49 - 67
Biomaterial aspects of Interpore-200 porous hydroxyapatite; White E et al.; Interpore-200 is the product of over 11 years of continuous research and development . It has been investigated at over 25 research centers in a wide variety of animal and human implant settings, including alveolar ridge augmentation, periodontics, and orthognathic reconstructions . The biomaterial aspects of Interpore-200 show the following: Interpore-200 has a highly interconnected, three-dimensional porosity that is uniform and consistent . The hydroxyapatite manufactured from marine corals is biocompatible and nontoxic . Interpore-200 is essentially pure hydroxyapatite, with the balance consisting of tricalcium phosphate . Interpore-200 is approximately 55 to 65 per cent porous with nominal pore diameters of 200 micron . Unlike nonporous materials, Interpore-200 is osteoconductive and results, when placed next to a viable bone, in an advancing front of bone into the implant . From 50 to 88 per cent of the porosity within the implant is filled with woven and lamellar bone within 3 months . Moreover, the surfaces of Interpore-200 are intimately bonded with the bone tissue . The biomechanical properties of Interpore-200 blocks are similar to those of a cancellous bone graft . Once ingrown with vascularized bone tissue, the defect site is, in effect, restored . Interpore-200 adequately matches the elastic properties of bone so that stresses necessary to maintain healthy bone are transmitted throughout the regenerated region . Extensive animal and clinical studies have shown that nonporous implants or implants without interconnected porosity can result in aberrant mineralization, stress shielding, low fatigue strength, and bulk displacement . Hydroxyapatite with interconnected porosity like Interpore-200 reacts differently than materials with limited or no porosity . In animals, Interpore-200 exhibits 0 to 5 per cent biodegradation per year . Moreover, this minimal biodegradation is compensated by regeneration of bone . These studies have now been extended for 4 years . Interpore-200 and its ingrown bone are remodeled in response to the same chemical and biomechanical forces that remodel normal bone . Therefore, Interpore-200 responds in accordance to Wolff's law . Having achieved an optimal combination of biomaterial (hydroxyapatite) in an ideal porous structure (replamineform), Interpore-200 fulfills the expectation of early researchers in the basic sciences who demonstrated that an interconnected porous material is better tolerated by the body than the same material in solid form.(ABSTRACT TRUNCATED AT 400 WORDS)

Arch Orthop Trauma Surg, 1986, 104(6), 333 - 8
Biodegradation of polyglycolic acid in bone tissue: an experimental study on rabbits; Vainionpaa S; The biodegradation of polyglycolic acid (PGA) was investigated in cortical bone of 21 rabbits and in cancellous bone of 15 rabbits . The follow-up times were 3, 6, and 12 weeks . Radiographical, histological, microradiographical, and oxytetracycline labeling studies were done . PGA was biocompatible and was degraded to a great extent in the cancellous bone and partly in the cortical bone in 12 weeks without any sign of inflammation or foreign body reaction . The biodegradation of PGA started peripherally in the area of the implant and continued with subsequent replacement by new bone.

Med Hypotheses, 1986 Jan, 19(1), 57 - 69
Bile acid-induced liver toxicity: relation to the hydrophobic-hydrophilic balance of bile acids; Attili AF et al.; Hypertransaminasemia is a frequent side effect during chenodeoxycholic administration for gallstone dissolution . Evidence suggests that this effect is not mediated by lithocholic acid, the intestinal metabolite of chenodeoxycholic acid, but that toxicity is due to the chenodeoxycholic acid itself . In vitro cytotoxicity of bile salts is positively proportional to their detergent effect, which is, on the other hand, related to their hydrophobic-hydrophilic balance . We hypothesize that in vivo also liver injury can occur when the liver is perfused by an high proportion of strongly detergent bile salts . The more detergent bile salts are unconjugated or glycine conjugated, while the lesser are taurine conjugated and sulfated . Within each class the following order of decreasing detergent power can be indicated: lithocholic greater than deoxycholic greater than chenodeoxycholic greater than cholic greater than ursodeoxycholic acid . Besides chronic exogenous administration of chenodeoxycholic or deoxycholic acids, conditions in which the liver is perfused by an high mass of highly detergent bile salts are those characterized by an enhanced intestinal biodegradation of bile salts . These conditions, which are common features of some chronic inflammatory bowel diseases, are frequently associated with liver damage . On the other hand, a normally detergent bile salt pool can become hepatotoxic for liver cells which have already been injured . In this respect, as already reported for increased sulfation, the increased proportion of taurine conjugates and the reduced formation of deoxycholic acid in liver cirrhosis can be regarded as protective mechanisms . Liver toxicity induced by bile salts' detergent action can be prevented by favouring tauroconjugation or reducing the intestinal degradation of bile salts or by administering poorly detergent bile salts.

J Biochem (Tokyo), 1985 Dec, 98(6), 1591 - 6
Treatment with phorbol esters leads to spermine depletion and inhibition of DNA synthesis in phytohemagglutinin-activated bovine lymphocytes; Matsui-Yuasa I et al.; Phorbol 12-myristate-13-acetate (PMA) inhibited an increase in {3H}thymidine incorporation induced by phytohemagglutinin (PHA) in cultured bovine lymphocytes . Cellular levels of putrescine increased in the presence of PHA and PMA but the levels of spermidine and spermine had decreased to the control levels by 40 h . In cells treated with PHA and PMA, the activity of spermidine/spermine N1-acetyltransferase, a rate-limiting enzyme in polyamine biodegradation, was stimulated synergistically . Phorbol esters with tumor-promoting ability also stimulated the enzyme activity and a reciprocal correlation between the enzyme activity and DNA synthesis was observed . Addition of spermine reversed the PHA- and PMA-induced inhibition of DNA synthesis but putrescine and spermidine failed to restore it . These results suggest that the enhancement of spermidine/spermine N1-acetyltransferase activity results in the depletion of intracellular spermine and a concomitant decrease in DNA synthesis.

Appl Environ Microbiol, 1985 Oct, 50(4), 977 - 83
Reasons for possible failure of inoculation to enhance biodegradation; Goldstein RM et al.; Pseudomonas strains capable of mineralizing 2,4-dichlorophenol (DCP) and p-nitrophenol (PNP) in culture media were isolated from soil . One DCP-metabolizing strain mineralized 1.0 and 10 micrograms of DCP but not 2.0 to 300 ng/ml in culture . When added to lake water containing 10 micrograms of DCP per ml, the bacterium did not mineralize the compound, and only after 6 days did it cause the degradation of 1.0 microgram of DCP per ml . The organism did not grow or metabolize DCP when inoculated into sterile lake water, but it multiplied in sterile lake water amended with glucose or with DCP and supplemental nutrients . Its population density declined and DCP was not mineralized when the pseudomonad was added to nonsterile sewage, but the bacterium grew in sterile DCP-amended sewage, although not causing appreciable mineralization of the test compound . Addition of the bacterium to nonsterile soil did not result in the mineralization of 10 micrograms of DCP per g, although mineralization was evident if the inoculum was added to sterile soil . A second DCP-utilizing pseudomonad failed to mineralize DCP when added to the surface of sterile soil, although activity was evident if the inoculum was mixed with the soil . A pseudomonad able to mineralize 5.0 micrograms of PNP per ml in culture did not mineralize the compound in sterile or nonsterile lake water . The bacterium destroyed PNP in sterile sewage and enhanced PNP mineralization in nonsterile sewage . When added to the surface of sterile soil, the bacterium mineralized little of the PNP present at 5.0 micrograms/g, but it was active if mixed well with the sterile soil.(ABSTRACT TRUNCATED AT 250 WORDS)

J Microencapsul, 1985 Oct-Dec, 2(4), 293 - 304
In vitro release of adriamycin from drug-loaded albumin and haemoglobin microspheres; Willmott N et al.; Release of adriamycin from albumin and haemoglobin microspheres has been determined in vitro using a flow through system . Release from cross-linked albumin microspheres is controlled by the percentage of glutaraldehyde used but release profiles of spheres of 23, 41 and 60 microns diameter were virtually superimposable . Not all of the adriamycin is released from the microspheres over 20 h; as biodegradation occurs in vivo after 24 h the amount of drug remaining in the system at 20 h is likely to be principally released by degradation of the protein matrix in vivo . Estimates of the retained adriamycin vary from 16-26 per cent for albumin (n = 3) and 30 per cent for haemoglobin (n = 1).

FEBS Lett, 1985 Sep 2, 188(2), 375 - 8
Calcium ionophore A23187 induction of spermidine/spermine N1-acetyltransferase activity in bovine lymphocytes; Matsui-Yuasa I et al.; The divalent cation ionophore A23187 increased the activity in bovine lymphocytes of spermidine/spermine N1-acetyltransferase, a rate-limiting enzyme in polyamine biodegradation . The enzyme was induced in a dose- and time-dependent manner . Induction was suppressed by indomethacin, but not by trifluoperazine (TFP), N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) or palmitoylcarnitine . These results suggest that the activation of phospholipase A2 involves the induction of spermidine/spermine N1-acetyltransferase . Ornithine decarboxylase, a rate-limiting enzyme in polyamine biosynthesis, was not suppressed by indomethacin but was by TFP and W-7 . The molecular mechanism of the induction of spermidine/spermine N1-acetyltransferase and ornithine decarboxylase may be different.

Biochimie, 1985 Sep, 67(9), 973 - 86
A new bacterial dehydrogenase oxidizing the lignin model compound guaiacylglycerol beta-O-4-guaiacyl ether; Pelmont J et al.; A lignin model compound, named in short guaiagylglycerol beta-guaiacyl ether (GGE), contains the beta-0-4 ether linkage that is common in the chemical structure of lignin . A Pseudomonas sp . (GU5) had been isolated as an organism able to grow with GGE as the sole source of carbon and energy . When grown on vanillate, the bacteria contained a NAD+ -dependent dehydrogenase converting GGE to a 355 nm absorbing product . The enzyme, named GGE-dehydrogenase, was purified about 160-fold using gel permeation, ion exchange on DEAE-Sephadex, and dye-ligand affinity chromatography . The new protein was about 52 kDa in apparent size with but one polypeptide chain after denaturation and reduction . According to several criteria, the product of GGE oxidation (Km = 12 microM) was identified as the corresponding conjugated ketone at the alpha-carbon of the C3 side-chain . The secondary alcohol function in GGE was apparently the sole target of the enzyme action . However the conversion of GGE into ketone catalyzed by the enzyme was only partial, and did not exceed 50%, probably because only one of the alpha-enantiomers was susceptible to enzyme attack . In contrast the ketone, either made by organic synthesis or by enzymic oxidation of GGE, could be totally reduced back to GGE (Km = 13 microM at pH 8.4, 8 microM at neutral pH), with NADH as the reductant, as confirmed by UV absorption and NMR spectra . Other model compounds with no primary alcoholic function, ether linkage or phenolic group were also substrates for the enzyme, confirming the specificity of GGE-dehydrogenase for the alpha-carbon position . Conjugation of the alpha-ketone with an adjacent phenolic nucleus interfered strongly with equilibrium constants and redox potentials of the system according to pH, and the enzyme displayed widely different optima with pH over 9 when oxidizing GGE, below 7 when reducing the ketone . Equilibrium studies showed that the ketone/GGE potential was -0.37 volt at pH 8.7, -0.23 volt at pH 7 (30 degrees C) . The significance of this new dehydrogenase and its properties are discussed, especially in the general concern of lignin biodegradation.

Mikrobiologiia, 1985 Sep-Oct, 54(5), 835 - 41
{Biodegradation of petroleum hydrocarbons in soil inoculated with yeasts}; Ismailov NM; Yeast species belonging to the Candida genus were added to the greyish-brown soil of the Apsheron Peninsula under laboratory conditions . The rate of CO2 production was used to estimate the degradation of crude oil, paraffin, cycloparaffin and aromatic hydrocarbons as well as their oxidized products . The rate of hydrocarbon degradation in the soil inoculated with yeast cells was shown to drop down gradually . The effective action on the process of hydrocarbon degradation depended on the special properties of an inoculated population and on the structure of a hydrocarbon . Some yeast species stimulated the degradation of various aromatic hydrocarbons and their oxidized products . Aromatic hydrocarbons were decomposed at a lower rate comparing to their oxidized products . When the soil was inoculated with C . guilliermondii populations, n-hexadecane added to the soil at a concentration of 1% was decomposed within 250-300 days . Field experiments confirmed that crude oil biodegradation was more intensive in the soil inoculated with yeast cells.

Biochem J, 1985 Jul 1, 229(1), 277 - 9
Exhaustive laccase-catalysed oxidation of a lignin model compound (vanillyl glycol) produces methanol and polymeric quinoid products; Lundquist K et al.; Laccase-catalysed oxidation of the lignin-related phenol vanillyl glycol results in the initial formation of dimers and subsequent polymerization . The polymerization is accompanied by a liberation of methanol corresponding to 15-20% demethylation . Visible spectra together with reduction experiments suggest the simultaneous formation of o-quinones . The participation of quinone formation in the polymerization process and the possible role of such intermediates in lignin biodegradation is discussed.

Appl Environ Microbiol, 1985 Jul, 50(1), 127 - 32
Response of the microflora in outdoor experimental streams to pentachlorophenol: compartmental contributions; Pignatello JJ et al.; Outdoor artificial streams were treated continuously with pentachlorophenol (PCP) for 88 days during the summer of 1983 . The contributions of different stream compartments (microbial habitats) to microbial degradation of PCP were determined in a stream treated with 144 micrograms of PCP per liter . The 488-m long stream was composed of mud-bottomed pools alternating with gravel riffles . PCP loss in the stream attributable to microbial degradation after an adaptation period was in the range of 55 to 74% . Contributions to PCP loss were determined for rock surface (epilithic), macrophyte surface (epiphytic), sedimentary, and water column communities by measuring rates of PCP disappearance in stream water, containing ambient concentrations of PCP, in contact with representative compartmental samples . The specific capability, in units of micrograms of PCP per hour per square meter of stream cross-sectional area (macrophytes at maximum plant density, water column at mean depth, upper 10-cm layer of gravel), followed the order rock surface much greater than macrophytes greater than sediment approximately equal to water column . The compartmental contribution to total stream losses in units of grams per hour followed the same order, although the differences were smaller . The rate of PCP disappearance in the water column above sediment cores followed the order oxygen-rich greater than oxygen-poor approximately equal to anaerobic greater than sorption-only conditions . The large difference in specific capability between the rock surface and sediment compartments could be attributed to oxygen deficiency (because of chemical and biological oxygen demand) in the sediments . Free-floating and particle-attached organisms in the water column were important to PCP biodegradation.

Clin Orthop, 1985 Jul-Aug, (197), 272 - 85
Bioresorption of ceramic strontium-85-labeled calcium phosphate implants in dog femora . A pilot study to quantitate bioresorption of ceramic implants of hydroxyapatite and tricalcium orthophosphate in vivo; Renooij W et al.; Ceramic hydroxyapatite and tricalcium orthophosphate were radioactively labeled with their strontium-85 analogs . Porous blocks of these materials (dimensions 2.5 X 1.25 X 0.5 cm) were implanted into surgically created defects in dog femora . The fate of the implants was studied by roentgenography, radioactivity measurements, histology, and microradiography . The radioactivity over the implant site was followed for 22 weeks . Implants were retrieved after 20-25 and 50-55 weeks . Hydroxyapatite implants were not affected by biodegradation processes, while tricalcium orthophosphate implants were subject to extensive bioresorption (25%-30% in 22 weeks) . Resorption debris from tricalcium orthophosphate implants was found in mononuclear phagocytes and multinuclear osteoclastlike cells . The supposition is that tricalcium orthophosphate is transformed into hydroxyapatite in a physiologic environment . Labeling of ceramic calcium phosphate implants with strontium-85 analogs offers an adequate technique to quantitate bioresorption in vivo.

J Vasc Surg, 1985 Jul, 2(4), 524 - 9
Aneurysm formation in human umbilical vein grafts used as arterial substitutes; Boontje AH; A series of 257 human umbilical vein grafts for femoropopliteal bypass in 203 patients, inserted between 1978 and 1984, is presented . The 6-year cumulative patency rate is 74% for above-knee and 44% for below-knee cases . Late complications, such as formation of aneurysms in the human umbilical vein graft, occurred in nine grafts, 21/2 to 6 years after implantation . This corresponds to 3.5% of the total number of 257 human umbilical vein grafts . Three of the grafts developed a second aneurysm at a later time, making a total of 12 aneurysms . The aneurysms were evident as a painful, pulsating mass . All patients were operated on, primarily by resection and interposition grafting . All aneurysms were saccular and false . Macroscopic and microscopic examination revealed that all aneurysms except four originated from a gap in the umbilical vein wall and the Dacron mesh . The adjacent graft wall had a completely normal architecture without biodegradation . The cause of the origin of the gap in the wall remains obscure . Four aneurysms were anastomotic and were located at the site of the suture line, placed at the factory, joining the two components of a composite human umbilical vein graft; these anastomotic aneurysms were caused by breaking of the Prolene suture.

Arch Biochem Biophys, 1985 Jun, 239(2), 420 - 6
Activation and oligomerization of immobilized biodegradative L-threonine dehydrase; LeBlond DJ et al.; Biodegradative L-threonine dehydrase of Escherichia coli (radio labeled with {3H}pyridoxine) was immobilized on CNBr-activated Cl-Sepharose . The specific catalytic activity and S0.5 values of the matrix-bound dehydrase in the presence of AMP were similar to those of the soluble oligomeric enzyme in the presence of AMP (matrix-bound, associated dehydrase) . When the bound dehydrase was washed with AMP-free buffer, about 50% of the bound dehydrase was removed and about 50% remained attached, as measured by radioactivity . The resulting matrix-bound, dissociated dehydrase possessed activity in the absence of AMP as is characteristic of soluble, unactivated dehydrase . The bound, dissociated dehydrase was capable of binding nearly an equal amount of soluble dehydrase in the presence of AMP; this treatment raised the specific enzyme activity of the bound dehydrase to 83% of that of the original matrix-bound, associated dehydrase . These observations correlate with the effects of AMP on the activity and quaternary structure of soluble dehydrase . When AMP was added to the matrix-bound, dissociated dehydrase, the activation observed was only a small fraction of that obtained with soluble dehydrase plus AMP . The failure of AMP to activate the major fraction of immobilized dehydrase monomer strongly suggests that dimerization is required in the activation by AMP.

Biomaterials, 1985 May, 6(3), 189 - 92
Interaction of biodegradable beta-whitlockite ceramics with bone tissue: an in vivo study; Klein CP et al.; The biodegradation of different porous beta-whitlockite materials are studied by in vivo experiments, radiographic follow-ups and light microscopy observations . The materials were implanted in rabbit tibiae for 16 month . Micropores play an important role in the biodegradation rate . The resorbing materials evoke an inflammation with plasma cells . The resorption starts in the medulla, and the phagocytosed particles are removed to the lymph nodes . Normal bone function can be restored after all the implant material is resorbed.

Appl Environ Microbiol, 1985 May, 49(5), 1290 - 4
Mechanism of biodegradation of paraquat by Lipomyces starkeyi; Carr RJ et al.; The biodegradation of ring-14C- and methyl-14C-labeled paraquat by the soil yeast Lipomyces starkeyi was studied in vitro . It was found that the degradation of paraquat (acting as a sole source of culture nitrogen) resulted in the accumulation in the extracellular medium of radiolabeled acetic acid . The culture also evolved radiolabeled CO2 . The results suggest that the degradation of paraquat by L . starkeyi is associated with the integrity of the cell wall and that disruption or removal of the wall results in a complete loss of degradative capability . A mechanism for the degradation of paraquat by this organism is postulated.

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