Biodegradation

Antibiot Med Biotekhnol, 1985 May, 30(5), 337 - 41
{Resistance to organic tin compounds mediated by plasmids of bacteria of Pseudomonas genus}; Anisimova LA et al.; Resistance to organic tin compounds of P . aeruginosa and E . coli carrying antibiotic resistance plasmids and to P . putida containing biodegradation plasmids was studied . It was shown that 5 resistance plasmids and the biodegradation CAM plasmid of Pseudomonas increased 3-4 times the strain resistance to triethylstannylsuccinylimide and triethylstannylmaleinimide . All these plasmids belong to the P-2 incompatibility group and also determine the bacterial resistance to potassium tellurite . Isolation and investigation of the mutant plasmids loosing simultaneously the capacity for determination of resistance to potassium tellurite and organic tin compounds suggest that resistance to these compounds in the investigated plasmids is determined by the same genetic system.

Biochem Soc Trans, 1985 Apr, 13(2), 516 - 20
The use of controlled-release glass for the controlled delivery of bioactive materials; Drake CF et al.; CRG can provide a useful supplement to other methods of controlled delivery . Some advantages of this approach are: The constituents of the CRG can be limited to biologically safe ionic species such as Na+, Ca2+ and PO4(3-) . The release system is completely soluble in water and no residue remains . There is no evidence of any mechanism for biodegradation of the CRG and so one possible cause of premature or accelerated release is eliminated . The absolute release rate can be selected anywhere in a spectrum covering several orders of magnitude and the rate-controlling process has zero-order kinetics . The release rate can be selected to be pH-sensitive or pH-independent . Complex temporal release-rate patterns can be obtained readily by the choice of geometrical shape or composition profile of the device . The controlled release of organics or other heat-sensitive materials which cannot be incorporated in the glass can be realized by the use of composite structures in which the CRG is the rate-controlling constituent . A number of different functions can be performed by a single CRG-based device . For example, CRG can be used as a biomedical resorbable material in surgery and the CRG structural component can release an AM as it dissolves . Similarly the CRG of the sinter-composite used for organic AM release can itself release any selected inorganic adjuvant . CRG boluses containing either copper or cobalt and weighing approx . either 70 g or 15 g, have been administered to both cattle and sheep . More than 90% of the boluses remained either in the reticulum of trace element remained after dosing.(ABSTRACT TRUNCATED AT 250 WORDS)

Appl Environ Microbiol, 1985 Apr, 49(4), 867 - 9
Biodegradation of {14C}phenol in secondary sewage and landfill leachate measured by double-vial radiorespirometry; Deeley GM et al.; Double-vial radiorespirometry was used to estimate the biodegradation rates of 14C-labeled phenol in a landfill leachate and a secondary treated domestic wastewater . Rates were found to be comparable for each material at each of the three concentrations tested . Sewage microorganisms immediately began biodegrading the {14C}phenol; landfill leachate microorganisms required a lag period before maximum biodegradation of the {14C}phenol . The apparent rate of {14C}phenol biodegradation was 2.4 times faster in the sewage than in the landfill leachate . Double-vial radiorespirometry was shown to be an effective method for screening biodegradation rates in aquifers.

Ecotoxicol Environ Saf, 1985 Apr, 9(2), 159 - 70
Formation and fate of bound residues of {14C}benzene and {14C}chlorobenzenes in soil and plants; Scheunert I et al.; Outdoor experiments with {14C}hexachlorobenzene, {14C}pentachlorobenzene, {14C}1,2,4-trichlorobenzene, and {14C}benzene in soil-crop systems indicate that the formation rate of bound residues in soil and plants, expressed as bound residues in percentage of total residue in the sample, decreases with increasing number of chlorine in the molecule and, thus, with increasing chemical stability . The time course of formation and fate of bound residues in soil and plants is characterized by a very slow decrease of residue levels in soil, indicating that biodegradation of bound residues hardly exceeds their reformation from the parent compound during one vegetation period, and by a decrease of residue levels in plants . The portion of bound residues as compared to the total residue increases with time, indicating that bound residues are more persistent than the parent compounds and their soluble metabolites; benzene is an exception . Cress plants, in general, contain less bound residues than do barley plants . Again, benzene is an exception . In deeper soil layers, soil-bound residues occur also . The ratio between bound and extractable residues does not differ to a larger extent between the soil layers.

Genetika, 1985 Apr, 21(4), 522 - 9
{Plasmids for naphthalene biodegradation incompatible with IncP-2 and IncP-7 group plasmids}; Kochetkov VV et al.; Fourteen conjugative naphthalene degradative plasmids have been classified by incompatibility . It is shown that the plasmids of IncP-9 group are characterized by the minor entry exclusion, with respect to the R plasmids belonging to IncP-2 or IncP-7 groups . On the other hand, the naphthalene degradative plasmids of incompatibility group P-7 exhibit a markedly pronounced entry exclusion, with respect to the R plasmids of the same incompatibility groups . Two naphthalene degradative plasmids reveal incompatibility with the reference plasmids of two Inc groups (P-2 and P-7) . These plasmids control also resistance of bacterial cells to potassium tellurite, which is characteristic of the IncP-2 plasmids . Two other naphthalene degradative plasmids are capable of stable coexistence with the IncP-2, P-7 or P-9 reference plasmids.

J Biomed Mater Res, 1985 Mar, 19(3), 349 - 65
Biodegradation of and tissue reaction to 50:50 poly(DL-lactide-co-glycolide) microcapsules; Visscher GE et al.; The biodegradation of the copolymer 50:50 poly(DL-lactide-co-glycolide)-lypressin microcapsules was studied by light and electron microscopic methods and 14C release . Intramuscular injection sites of microcapsules in rats were studied by dissecting and conventional light microscopy as well as scanning (SEM) and transmission electron microscopy . A minimal localized acute myositis was seen initially at the injection sites . By Day 4, a few small foreign body giant cells were present participating in the minimal foreign body response . Later the inflammatory cells decreased and the individual microcapsules were walled off by immature fibrous connective tissue and large syncytial foreign body giant cells . By Day 35, definitive changes in some microcapsules, consisting of a granular and slightly eroded appearance of the internal matrix, were seen by SEM . By Day 42, the outer rims of the microcapsules were extensively eroded . At Day 56, the inflammatory and connective tissue reactions were almost completely resolved and biodegradation continued so that only remnant pieces of the microcapsules were present at Day 63 . The morphologic picture correlated well with loss of 14C radioactivity, which could no longer be detected at the injection sites on Day 56 . Phagocytosis did not seem to be an important factor in the biodegradation.

Biosci Rep, 1985 Mar, 5(3), 189 - 204
Regulation of polyamine biosynthesis by antizyme and some recent developments relating the induction of polyamine biosynthesis to cell growth . Review; Canellakis ES et al.; This review considers the role of antizyme, of amino acids and of protein synthesis in the regulation of polyamine biosynthesis . The ornithine decarboxylase of eukaryotic cells and of Escherichia coli can be non-competitively inhibited by proteins, termed antizymes, which are induced by di- and poly- amines . Some antizymes have been purified to homogeneity and have been shown to be structurally unique to the cell of origin . Yet, the E . coli antizyme and the rat liver antizyme cross react and inhibit each other's biosynthetic decarboxylases . These results indicate that aspects of the control of polyamine biosynthesis have been highly conserved throughout evolution . Evidence for the physiological role of the antizyme in mammalian cells rests upon its identification in normal uninduced cells, upon the inverse relationship that exists between antizyme and ornithine decarboxylase as well as upon the existence of the complex of ornithine decarboxylase and antizyme in vivo . Furthermore, the antizyme has been shown to be highly specific; its Keq for ornithine decarboxylase is 1.4 X 10(11) M-1 . In addition, mammalian cells contain an anti-antizyme, a protein that specifically binds to the antizyme of an ornithine decarboxylase-antizyme complex and liberates free ornithine decarboxylase from the complex . In E . coli, in which polyamine biosynthesis is mediated both by ornithine decarboxylase and by arginine decarboxylase, three proteins (one acidic and two basic) have been purified, each of which inhibits both these enzymes . They do not inhibit the biodegradative ornithine and arginine decarboxylases nor lysine decarboxylase . The two basic inhibitors have been shown to correspond to the ribosomal proteins S20/L26 and L34, respectively . The relationship of the acidic antizyme to other known E . coli proteins remains to be determined . In mammalian cells, ornithine decarboxylase can be induced by a broad spectrum of compounds . These range from hormones and growth factors to natural amino acids such as asparagine and to non-metabolizable amino acid analogues such as alpha-amino-isobutyric acid . The amino acids that induce ornithine decarboxylase as well as those that promote polyamine uptake utilize the sodium dependent A and N transport systems . Consequently, they act in concert and increase intracellular polyamine levels by both mechanisms . The induction of ornithine decarboxylase by growth factors, such as NGF, EGF, and PDGF as well as by insulin requires the presence of these same amino acids and does not occur in their absence . However, the inducing amino acid need not be incorporated into protein nor covalently modified.(ABSTRACT TRUNCATED AT 400 WORDS)

J Biomed Mater Res, 1985 Mar, 19(3), 293 - 301
In vivo corrosion of sodium silicate glasses; Pernot F et al.; Square-shaped implants of various sodium silicate glasses were weighed and implanted intraperitoneally in rat for periods ranging from 8 to about 60 days . The implants were then removed and their aspect was compared to their aspect before exposure to physiological environment . The corrosion products were studied by x-ray diffraction and electron microprobe analysis . Weight changes were also measured to calculate a biodegradation rate . The glass 66 SO (66.6 SiO2-33.3 Na2O) was strongly corroded, as early as after the first week . The nonsoluble degradation products formed a cocoon encapsulating the now smaller specimen . The analysis of the cocoon showed that it was made of a silica-rich layer containing also calcium and phosphorus . In this layer the ratio Ca/P could correspond to that of an apatite . The biodegradation rate reached 71 x 10(-4) g . cm-2 . day-1 . The glass 75 SO (75 SiO2-25 Na2O) was not so quickly corroded: Cracks appeared at the surface and progressively reached the center of the implants . There was no removable shell but a white deposit, adherent to the surface . This deposit contained silica and also calcium and phosphorus at the periphery . The biodegradation rate was only 2.6 x 10(-4) g . cm-2 . day-1.

Biochem J, 1985 Mar 1, 226(2), 455 - 60
Free hydroxyl radical is not involved in an important reaction of lignin degradation by Phanerochaete chrysosporium Burds; Kirk TK et al.; Hydroxyl radical (HO.) has been implicated in the degradation of lignin by Phanerochaete chrysosporium . This study assessed the possible involvement of HO . in degradation of lignin substructural models by intact cultures and by an extracellular ligninase isolated from the cultures . Two non-phenolic lignin model compounds {aryl-C(alpha)HOH-C(beta)HR-C(gamma)H2OH, in which R = aryl (beta-1) or R = O-aryl (beta-O-4)} were degraded by cultures, by the purified ligninase, and by Fenton's reagent (H2O2 + Fe2+), which generates HO. . The ligninase and the cultures formed similar products, derived via an initial cleavage between C(alpha) and C(beta) (known to be an important biodegradative reaction), indicating that the ligninase is responsible for model degradation in cultures . Products from the Fenton degradation were mainly polar phenolics that exhibited little similarity to those from the biological systems . Mass-spectral analysis, however, revealed traces of the same products in the Fenton reaction as seen in the biological reactions; even so, an 18O2-incorporation study showed that the mechanism of formation differed . E.s.r . spectroscopy with a spin-trapping agent readily detected HO . in the Fenton system, but indicated that no HO . is formed during ligninase catalysis . We conclude, therefore that HO . is not involved in fungal C(alpha)-C(beta) cleavage in the beta-1 and beta-O-4 models and, by extension, in the same reaction in lignin.

Ecotoxicol Environ Saf, 1985 Feb, 9(1), 6 - 16
A respirometric method for the assessment of ready biodegradability: results of a ring test; Painter HA et al.; A collaborative exercise involving twelve laboratories was organized for the European Economic Community to check the validity of an enclosed respirometric method for assessing the ready biodegradability of test chemicals, including insoluble substances . The method, based partly on the OECD-Japanese Ministry of International Trade and Industry (MITI) I method (301C) and partly on the U.K . method, allowed the use of a less restrictive, natural inoculum and a wider variety of respirometers than the original MITI I method . Eight compounds of a wide range of degradative behavior were tested over an incubation period of 28 days . The agreement between participating laboratories in the lag period before biodegradation started and in the proportions of theoretical oxygen uptake achieved was at least as good as in other ring tests; it is proposed that the method be accepted . Differences in behavior of pentaerythritol reported here and in the literature are examined and suggestions for future study are discussed.

Langenbecks Arch Chir, 1985, 363(4), 273 - 82
{Regeneration of the trachea following partial or total replacement by synthetic resorbable material (polyglactin 910)}; Greve H et al.; Though longer distances of the trachea and segments of the bronchi can be resected and the blunts be joined by end-to-end anastomosis, the replacement of parts of the wall of the tracheobronchial tree may become necessary . Alloplastic not absorbable material like silicone was not successful because of its disposition to infections and development of stenosis . Absorbable suture material proved to be suitable in tracheal surgery and it was shown that texture of Polyglactin 910 (Vicryl) could even be used for replacement of the aortic wall . We used weaved tubes of 2.5 mm diameter as prostheses of this material . We partly resected the trachea in the throat of 30 rats and in a microsurgical procedure we replaced in 17 animals the whole circumference by the tube shaped prosthesis and in 13 animals a window in the trachea by a patch, cut from such a prosthesis . By pneumonia or granulation in the anastomosis region 11 rats died or had to be sacrificed untimely . The others survived in several periods up to 10 weeks . At the time of autopsy starting after 3 weeks, a newly formed trachea could be demonstrated, which is covered more and more with respiratory epithelium . By light microscopic and scanning microscopic examinations, the development of a new wall, similar to the normal one, was seen . This wall lacks only mucus glands, but contains structures similar to hyaline cartilage . Our absorbable prosthesis cannot prevent the development of stenosis by overshooting granulation in the early postoperative period, but very soon the material is absorbed and replaced by a structure similar to the normal wall . After biodegradation, problems appear by instability of the new tissue, because of collapsing during inspiration . This problem could be solved by covering the prosthesis by an additional supporting scaffold.

Biopharm Drug Dispos, 1985 Jan-Mar, 6(1), 91 - 104
Adriamycin-loaded albumin microspheres: preparation, in vivo distribution and release in the rat; Willmott N et al.; Adriamycin-loaded bovine albumin microspheres have been prepared by a technique that allows preparation and administration to animals on the same day . Criteria adopted for injection were that microspheres should be stable and of a size such as to become trapped in capillary beds . These conditions were fulfilled by preparing microspheres using glutaraldehyde concentrations greater than 0.5 per cent and the appropriate combination of stirring speed and continuous phase viscosity . After systemic administration rats were sacrificed at intervals and major visceral organs examined for entrapped microspheres and serum for released drug . Microspheres sieved out in the first capillary bed encountered, the lung, then following biodegradation they disappeared at a rate dependent on the amount of cross-linking agent used in their preparation . In contrast to bolus injection, serum drug levels after microsphere administration indicated an initial rapid release followed by a more protracted phase lasting at least 24 h . This latter observation is consistent with drug release during biodegradation of carrier.

Z Kardiol, 1985, 74 Suppl 6, 65 - 71
Temporary left heart bypass and total artificial replacement; Bucherl ES; Research into left heart assistance was initiated in Berlin in the 1960s with a small implantable pump between the left atrium and the aorta with an extracorporeal driving unit . From thereon, different blood pumps were developed from different materials, the latest types being made out of polyurethanes . Similar designs are used for the total artificial heart . Longest function times exceed 200 days, partly with problems similar to those of the artificial heart . Total artificial heart research began in 1962 . The present system consists of 2 polyurethane blood pumps divided by 3 membranes into blood and energy transmission chambers . The longest testing function time is now more than 2 years . The outside driving units of different sizes and designs are connected with tubes and special quick connectors to the right and left atrium, aorta and pulmonary artery . Air capsulae for pressure measurements are incorporated . In addition to all the interesting hemodynamic parameters a great deal of analysis on hematology, biochemistry and metabolic function has been done . The longest survival time in animals is over 200 days . Complications and problems are mostly due to the material, in which small lesions, cracks or slight flaws in fabrication or biodegradation are the starting point for thrombosis and later on calcification . The number of patients who should be given temporary cardiac assistance or total replacement is discussed.

Drugs Exp Clin Res, 1985, 11(9), 633 - 40
Recent advances in the use of microspheres for targeted therapy; Davis SS et al.; In recent years the concept of using small colloidal particles for the selective delivery of drugs has been explored experimentally using a variety of different physical systems (for example, phospholipid vesicles (liposomes), triglyceride emulsions, albumin microspheres) and routes of administration . In such studies the aim has been to target a potent pharmacological agent on an organ or tissue site, thereby reducing adverse reactions and side-effects, or to provide a means of controlled release . The design of appropriate delivery systems must take into account the nature of the target and physiological barriers to targeting as well as factors such as drug loading and drug release, stability of the carrier system and its biocompatibility and biodegradation . Targeting with microspheres can be divided into passive methods that rely upon physiological and physicochemical determinants such as entrapment in capillary beds (lungs - particle size) or uptake by phagocytic cells (liver-surface characteristics), an active method whereby the particle is directed to a specific site through the use of surface coatings (surfactants, glycolipids, monoclonal antibodies) or a material sensitive to an external influence . Candidate systems presently under study are described . These include lipid emulsions for intravenous administration and microspheres for intra-articular delivery.

Trans Ophthalmol Soc U K, 1985, 104 ( Pt 5), 517 - 21
Scanning electron microscope study on the biodegradation of IOL and suturing materials; Yamanaka A et al.; The biodegradation of the IOLs (27 cases: mainly prepupillary lens with pupillary fixation, irido-capsular and angle supported lens and a J loop lens for posterior chamber lens) and suturing materials of four cases have been studied by Scanning Electron Microscope (SEM) . The longest duration in the eye was 7.5 years and the shortest 0.3 year . The materials used for optics were PMMA with the exception of one case of glass . The materials for haptics were Nylon 6, Isot.PP, PMMA, PVDF, Polyimid and Pt-Ir . The suturing materials were Nylon 6 and Isot.PP . Nylon 6 degraded in the eye and Isot.PP degraded in the corneal tissue . But no biodegradation was observed in Isot.PP, PMMA, PVDF and Pt-Ir in the eye . In our investigations, biodegradation has some relationship to age (over 50 years old), duration (within 7.5 years) and inflammation of the eye, but ultimately biodegradation will depend on the individual situation . Degradation occurs most easily in the curved portion of Nylon 6.

Mol Gen Genet, 1985, 201(2), 308 - 14
Molecular cloning and expression of the biodegradative threonine dehydratase gene (tdc) of Escherichia coli K12; Goss TJ et al.; The biodegradative threonine dehydratase gene (tdc) of Escherichia coli was cloned by isolating a dehydratase negative mutant after Tn5 mutagenesis, cloning the tdc::Tn5 DNA into pBR322 and then replacing the Tn5 element on the plasmid in vivo . Subcloning and nucleotide sequence data revealed two distinct procaryotic promoter-like elements each containing a potential CAP-binding site and AT-rich regions, and a Shine-Dalgarno sequence . One of these putative promoters, P2, was located immediately upstream from the tdc coding region, and a second, P1, was approximately 1 kilobase upstream from P2 . Deletion of the potential CAP-binding site from P1 prevented tdc gene expression . However, removal of P2 and a large segment of the upstream DNA had no discernible effect on dehydratase synthesis . A 936-base pair open reading frame was found between P1 and the tdc coding region, which produced a polypeptide of about 32 kilodaltons . The data suggest that P1, and not P2, is necessary for tdc gene expression, and that the DNA sequences coding for the 32 KD polypeptide and threonine dehydratase are part of a single transcriptional unit.

J Biochem (Tokyo), 1985 Jan, 97(1), 387 - 90
Induction of spermidine/spermine N1-acetyltransferase by parathyroid hormone in rabbit costal chondrocytes in culture; Matsui-Yuasa I et al.; Parathyroid hormone (PTH) increased the activity of spermidine/spermine N1-acetyltransferase, a rate-limiting enzyme of polyamine biodegradation, in rabbit costal chondrocytes in culture . The enzyme activity increased in a dose-dependent manner after addition of PTH to the culture, reaching a maximum at 8 h . The increase in the enzyme activity was abolished by cycloheximide or actinomycin D . Dibutyryl cyclic AMP also induced the acetyltransferase to some extent . These results suggest that the induction of spermidine/spermine N1-acetyltransferase by PTH may play some significant role in the expression of the differentiated phenotype of chondrocytes.

J Pharm Pharmacol, 1985 Jan, 37(1), 1 - 12
The fate of pharmaceutical chemicals in the aquatic environment; Richardson ML et al.; Increased demands for potable water, especially where supplies are drawn from lowland rivers has necessitated a greater degree of water re-use . As water undertakings have a duty to maintain the wholesome quality of potable water supplies, increasing concern is being expressed over the presence of organic micro-contaminants (contaminants found at microgram litre-1 concentrations) . This study outlines some of the problems encountered in assessing the risk from pharmaceutical chemicals which might enter the water cycle from domestic and industrial sources . Analytical chemistry was of value for only a few of the 200 compounds studied . However, much useful information was derived from the human metabolic routes of the drugs and is collated in Appendix I . Biodegradation studies and other ecotoxicity/environmental toxicology data may be required to a greater extent in the future . Particular consideration is given to vulnerable sections of the population.

Ann N Y Acad Sci, 1985, 446, 67 - 75
In vitro and in vivo studies of drug-releasing poly(amino acids); Anderson JM; Preliminary efforts directed toward the synthesis and characterization of steroid-polyamino acid conjugates indicate that the preparation of these systems is feasible . Studies have indicated that the steroids may be released from the macromolecule resulting in long-term controlled release systems . Table 4 lists several of the variables that are important in controlling biocompatibility, biodegradation, and drug release characteristics . The biocompatibility, biodegradation, and drug release characteristics are all important in the design and preparation of a drug-polyamino acid delivery system . The variables listed in Table 4 may interact and interrelate to varying degrees when considering each of these factors independently . Although perhaps preliminary, efforts to date indicate that steroids bound to polyglutamic acid or polyglutamic acid derivatives are biocompatible, capable of undergoing biodegradation, and can release drugs at appropriate rates for extended periods of time.

FEBS Lett, 1984 Dec 10, 178(2), 297 - 300
Phorbol esters stimulate spermidine/spermine N1-acetyltransferase activity in mitogen-stimulated bovine lymphocytes; Matsui-Yuasa I et al.; Phorbol 12-myristate-13-acetate (PMA) is shown to induce spermidine/spermine N1-acetyltransferase, a rate-limiting enzyme of polyamine biodegradation, in bovine lymphocytes . When PMA and phytohemagglutinin (PHA) were added simultaneously, the enzyme activity was stimulated synergistically . The ability of phorbol esters to stimulate the enzyme activity was consistent with their tumor-promoting ability . Phorbol, which is not a tumor promotor, was incapable of stimulating the enzyme activity . Phorbol diacetate weakly stimulated the activity of the acetylase . Phorbol dibutyrate had a similar stimulatory effect to PMA . These results suggest that the spermidine/spermine N1-acetyltransferase may play an important role in changes in polyamine levels in phorbol ester-treated cells and that the increase in the enzyme activity may have some relationship to the control of cell growth and differentiation by phorbol esters.

J Steroid Biochem, 1984 Dec, 21(6), 763 - 71
Estrogen response of MCF-7 cells grown on diverse substrates and in suspension culture: promotion of morphological heterogeneity, modulation of progestin receptor induction; cell-substrate interactions on collagen gels; Pourreau-Schneider N et al.; In this study we observed the incidence of hormone sensitivity in the response of MCF-7 cells to estrogen stimulation when the cells were cultured in different contact environments (hydrophilic plastic, bovine corneal extracellular matrix, type I collagen and in suspension culture) . The major purpose was to describe the influence of cell to cell and cell to substrate contacts on the morphological response to estrogen treatment . However, other parameters including growth and induction of progestin receptor were also explored, keeping in mind that the MCF-7 cell line, although representative of normal mammary epithelium in that it contains a similar hormone receptivity, was selected in vitro from a metastatic population in a pleural effusion . Although substrate conditions did not modify growth enhancement by estrogens, progestin receptor levels were significantly higher in three-dimensional spheroid cultures in which cell to cell contacts were optimal due to elimination of basal contact . A careful morphological survey of large surfaces lead to an objective opinion of the overall effect of the hormone treatment on the non-cloned cell line in which a marked heterogeneity in the response of individual cells was observed . In terms of morphofunctional differentiation, the edification of acini with dense microvillus coating was best in suspension culture . When sections were made perpendicular to the plane of cultures on collagen gel rafts two other phenomena were noted: decrease in intercellular junctions, resulting in reduced cell to cell cohesion, and accumulation biodegradation products in the collagen lattice . This suggested a hormone-mediated interaction between the metastatic cells and the fibrillar substrate, collagen I, one of the major constituents of tissue stroma . This estrogen response might be related to the metastatic phenotype and must be distinct from their hormone sensitivity in terms of growth and differentiation since hormone receptivity is generally considered to be a favorable prognosis for breast cancer.

Laryngoscope, 1984 Nov, 94(11 Pt 1), 1443 - 6
Reconstruction of hearing when malleus is absent: TORP vs . homograft TMMI; Lesinski SG; To study the most appropriate ossicular reconstruction of patients with an absent malleus, a comparison was made utilizing a homograft tympanic membrane with attached malleus and shaped incus (TMMI) columella and the alternative use of underlay fascia tympanoplasty with a cartilage covered TORP . Forty-six patients were reconstructed with a homograft TMMI and 38 with cartilage covered TORP and underlay fascia technique; 4.5 years postoperatively, 84% of those patients reconstructed with a homograft TMMI maintained an average A/B gap of 25 dB or better . Though 1 year postoperatively the TORP hearing results were satisfactory, only 18% of the TORP patients maintained a hearing level within 25 dB A/B gap at 4 years postoperatively . Primary causes of failure of the TORP were instability with migration off the stapes footplate, protrusion or extrusion through the TM and finally, long-term softening and bending secondary to biodegradation of the Plastipore . The discouraging long-term hearing results found in the TORP patients in this study confirm similar findings reported in 1982 by Smyth in a 5 year follow-up on 116 TORP patients.

Ecotoxicol Environ Saf, 1984 Oct, 8(5), 471 - 81
Fate and biological effects of methyl parathion in outdoor ponds and laboratory aquaria . I . Fate; Crossland NO et al.; Three outdoor ponds were treated with methyl parathion (MEP) applied beneath the water surface at a concentration of 100 micrograms liter-1 . Laboratory aquaria containing either tap water, pond water, tap water plus plants, tap water plus sediment, or tap water plus sediment and plants were similarly treated . Samples of water, sediment, and fish were analyzed for residues of MEP . The rate of loss from water and concentrations found in sediment were compared with predictions based on a calculated rate of biodegradation and a sediment:water partition coefficient . The rate of loss of MEP from pond water isolated in an aquarium was similar to the predicted rate . However, the rate of loss from outdoor ponds, or from aquaria containing plants and sediment, was greater than predicted . MEP was not detected in sediment even though predicted concentrations far exceeded the limit of detection . These results are discussed and it is suggested that the rate of biodegradation in shallow bodies of water may be determined predominantly by bacteria attached to sediments and plants, rather than by planktonic bacteria . Bioaccumulation in fish was predicted from empirical equations based on the octanol:water partition coefficient . Observed values were in good agreement with predictions.

Ecotoxicol Environ Saf, 1984 Oct, 8(5), 451 - 70
Biodegradation of 4-nitrophenol in standardized aquatic degradation tests; Nyholm N et al.; During the years 1978-1981 both the European Economic Community (the EEC) and the Organization for Economic Cooperation and Development (the OECD) organized various interlaboratory comparison programs on standardized screening methods to study the biodegradability of chemicals in water . While the ring test results were generally rather heterogenous, one of the compounds studied, 4-nitrophenol, turned out to be particularly problematic as the compound was found either easily biodegradable or not biodegradable by various laboratories in various tests . This paper describes some more detailed studies on 4-nitrophenol degradation in two different tests, the modified OECD screening test (MOST test) and the Zahn-Wellens test, respectively . The test variables investigated include inoculum characteristics and pretreatment, test duration, and 4-nitrophenol concentration . The results are discussed in relation to toxicity and degradation pathways of 4-nitrophenol . It is concluded that in order to improve the comparability of results from standardized aquatic biodegradation tests, test strategies should allow the option of performing a test with a preadapted inoculum in the event of negative test results with freshly collected inocula . Increasing the inoculated concentration of microorganisms in some tests may also contribute to the attainment of more consistent test results.

Int J Cardiol, 1984 Oct, 6(4), 423 - 9
Pacemaker leads; Harthorne JW; Present day pacemaker leads are far superior in every respect to those of the past . Modification of fixation characteristics has reduced displacement rates to 1% or less in most centers . Fracture of multifilar leads is a rarity . Biodegradation of polyurethane insulation appears to be an isolated problem specific to individual lead models and may be related to physical stresses incurred during manufacture or lead insertion . Recent evidence has incriminated an interaction of polyurethane with silver which arises from the drawn braised strand conductor substrate of those leads in which this problem has been noted . This may explain why the problem has been restricted to specific lead models of one manufacturer to date . Lack of uniformity of lead terminal size between manufacturers and even within the same manufacturer's product line continues to baffle this observer . Although past problems of lead displacement have been markedly reduced, the difficulty of removing chronic leads which have become septic appears to have worsened . Modification of existing leads to ensure that the interface between electrode tip and proximal shaft is unidiametric is essential.

Ecotoxicol Environ Saf, 1984 Oct, 8(5), 410 - 22
Biodegradability test results related to quality and quantity of the inoculum; Blok J et al.; For a series of different biodegradation test methods the biodegradation curves are simulated by computer . Simulations are performed on the basis of Monod growth kinetics corrected for cell decay . The possibility of discriminating between growth rates is related to variability of the inoculum quality and quantity . It is concluded that the variability of the inoculum masks all other information . The Repetitive Die Away test, however, offers a good opportunity to obtain information on growth rates that is highly relevant to environmental assessment . The conclusions derived from the computer-simulated curves are confirmed by experimental data.

J Microencapsul, 1984 Oct-Dec, 1(4), 317 - 27
Biodegradable cross-linked albumin microcapsules for embolization; Benita S et al.; The interfacial polymerization process used in the present study produced individual cross-linked albumin microcapsules, the particle size of which depended on the emulsification stirring rate . The variation in cross-linking agent concentration altered the microcapsule wall properties . As shown by SEM observations, microcapsules prepared with low acyl chloride concentrations presented rippled surfaces, while the surfaces of the microcapsules prepared with high acyl chloride concentrations were smooth . It was then suggested that the membranes of the weakly cross-linked microcapsules consisted of cross-linked and denatured albumin . Embolization experiments in the dog kidney showed that the weakly cross-linked microcapsules were biodegradable within 7 days, whereas the highly cross-linked microcapsules were degraded over more than 14 days and led to prolonged ischaemia . The results of the histological experiments carried out on a further eight dogs supported the previous findings yielded by the angiographical experiments . Moreover, they indicated that no foreign body reaction occurred . The lack of this inflammatory granuloma should be attributed to the rapid biodegradation of the microcapsules which produced reversible ischaemic lesions.

Appl Environ Microbiol, 1984 Sep, 48(3), 491 - 6
Mechanisms and pathways of aniline elimination from aquatic environments; Lyons CD et al.; The fate of aniline, a representative of arylamine pollutants derived from the manufacture of dyes, coal liquefaction, and pesticide degradation, was comprehensively evaluated by use of unpolluted and polluted pond water as model environments . Evaporation plus autoxidation proved to be minor elimination mechanisms, removing ca . 1% of the added aniline per day . Instantaneous binding to humic components of a 0.1% sewage sludge inoculum removed 4% . Biodegradation of aniline in pond water was accelerated by the sewage sludge inoculum . A substantial portion of the degraded aniline carbon was mineralized to CO2 within a 1-week period, and microbial biomass was formed as a result of aniline utilization . Biodegradation was clearly the most significant removal mechanism of polluting aniline from pond water . A gas chromatographic-mass spectrometric analysis of biodegradation intermediates revealed that the major pathway of aniline biodegradation in pond water involved oxidative deamination to catechol, which was further metabolized through cis,cis-muconic, beta-ketoadipic, levulinic, and succinic acid intermediates to CO2 . Minor biodegradation pathways involved reversible acylation to acetanilide and formanilide, whereas N-oxidation resulted in small amounts of oligomeric condensation products.

Appl Environ Microbiol, 1984 Aug, 48(2), 451 - 3
2-Chloro-4-amino-1,3,5-triazine-6(5H)-one: a new intermediate in the biodegradation of chlorinated s-triazines; Grossenbacher H et al.; Pseudomonas sp . strain A grew with 2-chloro-1,3,5-triazine-4,6-diamine as the sole and growth-limiting source of nitrogen . The substrate was utilized quantitatively and concomitantly with growth and with excretion of a product which was identified as 2-chloro-4-amino-1,3,5-triazine-6(5H)-one . The reaction yielded 1 mol of organic product and 1 mol of NH4+ per mol of substrate.

Br J Ind Med, 1984 Aug, 41(3), 389 - 95
In vitro biodegradation of chrysotile fibres by alveolar macrophages and mesothelial cells in culture: comparison with a pH effect; Jaurand MC et al.; The modification of the chemistry of asbestos chrysotile fibres (Mg3(Si2O5)(OH)4) after their ingestion by cultured cells has been studied . Two types of cells involved in asbestos related pulmonary disease were used, rabbit alveolar macrophages (AM), recovered by bronchoalveolar lavage, and pleural mesothelial cells (PMC) obtained from the rat parietal pleura . Chemical characterisation of intracellular fibres was performed on unstained ultrathin sections by electron probe microanalysis . The results showed a progressive leaching of Mg, characterised by a time dependent decrease of Mg/Si . AM were more efficient than PMC at leaching intracellular chrysotile fibres since it took longer to obtain the same proportion of leached fibres with PMC than with AM . As in vitro Mg-leaching can be obtained by acid treatment, chrysotile fibres were incubated, either untreated or pretreated with cell membranes, at pH 4 or 7 for various times . The data show that the kinetic of leaching by AM was comparable with leaching at pH 4 . The leaching by PMC was of the same order as leaching at pH 7 . When membranes were adsorbed on to the fibres, a delayed leaching was observed . The results indicate that the solubilisation of chrysotile by AM could be an intraphagolysosomal event due to a pH effect . With PMC, however, it is not possible to draw this conclusion since nothing is known about the intracellular pH.

Clin Orthop, 1984 Jul-Aug, (187), 281 - 8
Long-term study of large ceramic implants (porous hydroxyapatite) in dog femora; Hoogendoorn HA et al.; Blocks of porous ceramic hydroxyapatite (dimensions, 2.5 X 1.25 X 0.5 cm; sintering temperature, 1300 degrees; macroporosity, 56%; average pore size 0.18 mm2) were implanted into surgically created defects in dog femora . The implants were retrieved up to 3.5 years after implantation . The implants were 3.5 years after implantation . The implants were firmly attached to the bone . Histologic evaluation suggests that optimal contact between bone and implant should be provided to accelerate bone ingrowth . Bone growth in the pores reached a maximum level after 35 weeks, at which time about one-third of the pore space was filled with bone . When measuring the relative surface areas of bone and ceramic on histologic slides, no change in ceramic mass could be detected, indicating that hydroxyapatite ceramics are not affected by biodegradation processes . The implants effectively provided a scaffold for bone growth bridging a larger bone defect.

Mikrobiologiia, 1984 Jul-Aug, 53(4), 639 - 44
{Comparative study of the plasmids controlling naphthalene biodegradation by a Pseudomonas culture}; Kochetkov VV et al.; The object of this work was to study 25 Pseudomonas strains growing in a medium with naphthalene as a sole carbon source . Naphthalene catabolism was controlled by conjugative plasmids in 14 strains . The molecular mass of the plasmids was rather big, from 60 to 130 MD . The plasmids were classified in terms of their incompatibility group were assigned to the P-7 and P-9 groups five to each group . The incompatibility group could not be determined in four plasmids . The character of naphthalene catabolism controlled by the plasmids implies that only two of the plasmids control naphthalene oxidation via the "ortho" pathway of catechol cleavage which is an intermediate product in the oxidation of naphthalene . Just as most of the so far known plasmids controlling naphthalene biodegradation, seven of the plasmids studied in this work controlled naphthalene oxidation via the "meta" pathway of catechol cleavage.

Ecotoxicol Environ Saf, 1984 Jun, 8(3), 275 - 9
Comparison of methods for the biodegradability evaluation of soluble and insoluble organochemicals; Ruffo C et al.; Pyridine and nitrilotriacetic acid sodium salt as models of soluble compounds and linear dodecylbenzene, branched dodecylbenzene, and stearic acid as models of insoluble compounds were compared for their biodegradability in three tests: the ODCE modified test and the Sturm and enrichment culture tests . The degradation of soluble compounds was measured as dissolved organic carbon removal and CO2 evolution, while for the insoluble compounds, which were tested only in the Sturm test, CO2 evolution was determined . The individual tests were characterized by comparing their results with those obtained in the others . Comparable biodegradation values higher than 90% were obtained for the soluble compounds . The Sturm test proved to be very suitable for the evaluation of biodegradability of either soluble or insoluble compounds.

Can J Microbiol, 1984 Jun, 30(6), 786 - 92
Impact of an oil field effluent on microbial activities in a Wyoming river; Heitkamp MA et al.; The survival, functions, and physiological diversity of autochthonous sediment microbiota were examined in situ at five stations along the Little Popo Agie River, WY; one station above, one at, and three below a discharge point for oil wastewater from Union Oil Company's Dallas Field . Below the oil wastewater discharge point there were increases in electron-transport activity, carbon dioxide production, and microbial populations of heterotrophs, ammonifiers, hexadecane degraders, starch hydrolyzers, protein hydrolyzers, and sulfate reducers . At a station 1420 m below the discharge point, however, overall sediment microbial activities and all of the physiological groups of bacteria, except hexadecane-degrading microbiota, were at levels comparable with those at the control station above the discharge point . Similarly, mineralization of glucose, amino acids, hexanoic acid, and hexadecane was elevated at stations directly below the discharge point, but appeared to subside rapidly . Xenobiotic biodegradation potential of the sediments varied with the chemical and the sample location and was not directly related to oil residue levels in the sediment . Microorganisms thus appeared to maintain physiological diversity and increased in numbers and activity in a riverine environment that contained petroleum hydrocarbon concentrations known to be deleterious to freshwater fish and macrobenthic communities.

J Bacteriol, 1984 Jun, 158(3), 826 - 31
Escherichia coli K-12 mutation that inactivates biodegradative threonine dehydratase by transposon Tn5 insertion; Goss TJ et al.; From a collection of kanamycin-resistant mutants of Escherichia coli K-12 isolated by transposon Tn5 mutagenesis, we have identified a mutant that lacks functional biodegradative threonine dehydratase (EC 4.2.1.16) by direct enzyme assay and by the loss of cross-reacting material with affinity-purified antibodies against the purified enzyme . Aerobic and anaerobic growth of this strain on various carbon sources failed to reveal a phenotype . Evidence for the insertional inactivation of threonine dehydratase by Tn5 was obtained by cloning the DNA segments flanking the Tn5 insertion site into pBR322 and hybridizing the cloned DNA to a synthetic oligodeoxynucleotide probe complementary to the DNA segment coding for a unique hexapeptide at the amino terminus end of the enzyme; the region of homology to the synthetic cDNA sequence appears to be located within about 500 nucleotides from one end of Tn5 . Genetic analysis with the transposon element that caused insertional inactivation located the tdc gene at min 67 on the E . coli chromosome.

Appl Environ Microbiol, 1984 Apr, 47(4), 850 - 7
General method for determining anaerobic biodegradation potential; Shelton DR et al.; A simple, generalized method was refined and validated to test whether an organic chemical was susceptible to anaerobic degradation to CH4 + CO2 . The method used digested sewage sludge diluted to 10% and incubated anaerobically in 160-ml serum bottles with 50 micrograms of C per ml of test chemical . Biodegradation was determined by the net increase in gas pressure in bottles with test chemicals over the pressure in nonamended sludge bottles . Gas production was measured by gas chromatography and by a pressure transducer . The latter method is recommended because of its speed, accuracy, and low cost . Sewage sludge from municipal digesters with 15- to 30-day retention times was found to be suitable . The sludge could be stored anaerobically at 4 degrees C for up to 4 weeks with satisfactory test results . p-Cresol, phthalic acid, and ethanol are suggested as reference chemicals to confirm sludge activity and method reliability . A revised anaerobic salts medium was developed which minimizes problems of a biological gas production (CO2), avoids precipitation, and meets the requirements of the anaerobic microbiota . When greater than 75% of the theoretical gas production was observed, the chemical was judged to be degradable, and when 30 to 75% of the expected gas was produced, it was termed partially degradable . This method has been tested on more than 100 chemicals of various physical properties and found to reproducibly determine anaerobic biodegradation potential . Of the chemicals tested, 46 were found to be anaerobically degraded . Sludges from nine different municipal treatment plants were surveyed for their ability to degrade nine chemicals which differed in susceptibility to degradation.(ABSTRACT TRUNCATED AT 250 WORDS)

Ecotoxicol Environ Saf, 1984 Feb, 8(1), 34 - 54
Fate and effects of 3,4-dichloroaniline (DCA) in marine plankton communities in experimental enclosures; Kuiper J et al.; The fate and effects of single doses of 3,4-dichloroaniline (DCA) on North Sea coastal plankton communities enclosed by large plastic bags (contents 1.5 m3) were studied in two experiments lasting 5 and 6 weeks, respectively . The biodegradation of DCA was also studied in laboratory experiments, which were carried out simultaneously, using water from the enclosed model ecosystems . DCA was not degraded in the laboratory tests and probably also not degraded in the enclosed plankton communities, although concentrations in the water decreased during the experiments . This decrease appeared to be partly caused by diffusion of DCA through the walls of the enclosures . After the addition of single doses of 2, 10, and 25 microgram liter-1 DCA no effects on the enclosed plankton community could be detected . The addition of 0.1 mg liter-1 DCA had a clear influence on the species composition and the biomass development of the phytoplankton, changed the relative species composition of the zooplankton, and resulted in lower numbers of bacteria . In addition to these effects 1 mg liter-1 DCA limited the phytoplankton growth and resulted in mortality and inhibition of growth of the copepods.

Ecotoxicol Environ Saf, 1984 Feb, 8(1), 15 - 33
Fate and effects of 4-chlorophenol and 2,4-dichlorophenol in marine plankton communities in experimental enclosures; Kuiper J et al.; The fate and effects of 4-chlorophenol (4CP) and 2,4-dichlorophenol (DCP) added to North Sea coastal plankton communities enclosed by large plastic bags were studied in three experiments of 4 to 6 weeks duration . The biodegradation of the compounds was studied in laboratory experiments using water from the enclosed ecosystems . 4CP and DCP, added at initial concentrations of 0.1-1.0 mg X liter-1, disappeared from the water in the enclosures in 5 to 23 days, 4CP generally being the less persistent . Degradation rates were generally comparable to those found in laboratory tests with the same water . 4CP was removed by biodegradation, and DCP was probably removed by a combination of biodegradation, photodegradation, and/or chemical degradation . Results indicated that biodegradation rates could be limited by lack of inorganic nutrients, leading to much lower degradation rates than would be expected from routine laboratory tests . Faster degradation after repeated addition of 4CP showed adaption of the bacterial community . Addition of 0.3 mg liter-1 4CP or DCP inhibited the phytoplankton growth rate slightly . The 1 mg liter-1 4CP or DCP inhibited the phytoplankton, changed the species composition, and also influenced the zooplankton . In two of the three experiments 1 mg liter-1 DCP resulted in a temporary lowering of bacterial numbers following the addition . In one experiment inhibitory effects were found after 4CP and DCP had disappeared from the water, pointing to the formation of a more toxic intermediate during the degradation of these compounds . The laboratory tests also indicated the formation of relatively stable intermediates . The concentrations causing the effects in the different bag experiments were quite similar . This indicates that, although the development of the plankton communities during the different experiments was different, the concentrations resulting in ecological effects are quite reproducible.

Anal Biochem, 1984 Feb, 136(2), 314 - 20
Determination of trace levels of fatty acid metal salts by high-performance liquid chromatography with fluorescence prelabeling; Hayashi K et al.; A simple method is described for picomole determinations of fatty acid metal salts . Fatty acid salts are directly labeled with 4-bromomethyl-7-methoxycoumarin in the presence of excess ethylenediaminetetraacetic acid tripotassium salt without any solvent extractions . The fluorescence derivatives of fatty acids are separated by reverse-phase high-performance liquid chromatography followed by fluorometric detection . The response of each fatty acid (C8-C18) calcium salt is linear from 1 to 50 micrograms/ml of samples . The detection limit is about 7 pmol . Good recoveries are obtained for the calcium salts of myrystic acid and soap (C8-C18, C18:1,2) . The new method is successfully applied to the study on biodegradation of fatty acids in river water.

Appl Environ Microbiol, 1984 Feb, 47(2), 272 - 7
Anaerobic biodegradation of chlorophenols in fresh and acclimated sludge; Boyd SA et al.; We investigated the anaerobic biodegradation of mono- and dichlorophenol isomers by fresh (unacclimated) sludge and by sludge acclimated to either 2-chlorophenol, 3-chlorophenol, or 4-chlorophenol . Biodegradation was evaluated by monitoring substrate disappearance and, in selected cases, production of 14CH4 from labeled substrates . In unacclimated sludge, each of the monochlorophenol isomers was degraded . The relative rates of disappearance were in this order: ortho greater than meta greater than para . For the dichlorophenols in unacclimated sludge, reductive dechlorination of the Cl group ortho to phenolic OH was observed, and the monochlorophenol compounds released were subsequently degraded . 3,4-Dichlorophenol and 3,5-dichlorophenol were persistent . Sludge acclimated to 2-chlorophenol cross-acclimated to 4-chlorophenol but did not utilize 3-chlorophenol . This sludge also degraded 2,4-dichlorophenol . Sludge acclimated to 3-chlorophenol cross-acclimated to 4-chlorophenol but not to 2-chlorophenol . This sludge degraded 3,4- and 3,5-dichlorophenol but not 2,3- or 2,5-dichlorophenol . The specific cross-acclimation patterns observed for monochlorophenol degradation demonstrated the existence of two unique microbial activities that were in turn different from fresh sludge . The sludge acclimated to 4-chlorophenol could degrade all three monochlorophenol isomers and 2,4- and 3,4-dichlorophenol . The active microbial population in this sludge appeared to be a mixture of populations present in the 2-chlorphenol- and 3-chlorophenol-acclimated sludges, both of which could utilize 4-chlorophenol . Experiments with 14C-radiolabeled p-chlorophenol, o-chlorophenol, and 2,4-dichlorophenol demonstrated that these compounds were converted to 14CH4 and 14CO2.

Biochem Biophys Res Commun, 1984 Jan 30, 118(2), 437 - 43
Fatty acyl-coenzyme A oxidase activity and H2O2 production in Phanerochaete chrysosporium mycelia; Greene RV et al.; Mycelia of the lignin-degrading fungus Phanerochaete chrysosporium consume O2 and produce extracellular H2O2 when incubated with fatty acyl-CoA substrates, even in the presence of mitochondrial respiratory chain inhibitors such as antimycin A and cyanide . These results suggest the possibility that peroxisomal fatty acyl-CoA oxidase activity in P . chrysosporium mycelia may be an important metabolic source for the extracellular H2O2 believed to be involved in lignin biodegradation.

Basic Life Sci, 1984, 28, 3 - 21
Microbial biodegradation of 2,4,5-trichlorophenoxyacetic acid and chlorophenols; Karns JS et al.; We have succeeded in isolating a pure culture of Pseudomonas cepacia, AC1100, from a chemostat enrichment culture experiment that is capable of growing on 2,4,5-trichlorophenoxyacetic acid as its sole source of carbon and energy . AC1100 is not only capable of degrading 2,4,5-T but is also able to completely or partially dehalogenate a wide variety of halophenols . The regulation of the dehalogenating ability of AC1100 has been investigated which demonstrates that the enzyme(s) which allow the conversion of 2,4,5-T to 2,4,5-TCP are constitutive, while the enzymes that allow the degradation of 2,4,5-TCP are inducible by 2,4,5-TCP (or some metabolite of 2,4,5-TCP) but not by 2,4,5-T or other halophenols which can serve as substrates . Moreover, the 2,4,5-TCP degradative pathway is repressed by the presence of an abundant alternative carbon source . The detailed pathway of 2,4,5-T degradation by AC1100 is currently under study . Although field tests have yet to be conducted, laboratory experiments have demonstrated rapid and complete degradation of 2,4,5-T from contaminated soil . Soil previously contaminated with as much as 5,000 micrograms of 2,4,5-T/g of soil could be detoxified by AC1100 treatment, allowing the growth of plants sensitive to less than 10 micrograms 2,4,5-T/g of soil . Moreover soil contaminated with as much as 20,000 micrograms of 2,4,5-T/g of soil showed greater than 90% degradation after six weekly AC1100 treatments . After 2,4,5-T has been substantially degraded in contaminated soil the titer of AC1100 rapidly falls to nearly undetectable levels, which indicates that no serious ecological disturbance is likely to result from the application of AC1100 . It appears possible that the treatment of contaminated areas with appropriate microorganisms may allow essentially a total restoration of the original soil condition.

Basic Life Sci, 1984, 28, 137 - 49
Land disposal and spill site environments; Middleton AC; Land is a receptor of many chemicals through both intentional and unintentional depositions . Mitigation methods for control of the chemicals resulting from unintentional depositions such as unsuccessful landfills, spills, and leaks include excavation and disposal, entombment in place, and in some situations, in situ biodegradation . If genetically engineered bacteria could expand the number of situations where in situ degradation is applicable, then more economically efficient control methods resulting in the destruction of chemicals would be available . This paper outlines the various processes affecting the fate of organic chemicals in the soil environment, summarizes the environmental conditions encountered by organisms, and reviews two case histories of biodegradation of chemicals within the soil environment . Environmental conditions encountered by organisms are distinctly different in the two major soil zones: the unsaturated zone and the saturated zone . Chemicals may be present within the soil environment including the vapor phase, the adsorbed phase, and the soluble phase . These differences affect the fates of each chemical and result in greatly different rates of biodegradation of chemicals by naturally occurring microorganisms . Case histories discussed are that of a spray irrigation field treating wastewater from a creosote wood treating process, and that of an in situ biodegradation program for clean up of surface soils contaminated with pentachlorophenol . Recommendations for bacterial characteristics that could be engineered to greatly expand the applicability of in situ biodegradation are made.

Ann Surg, 1984 Jan, 199(1), 61 - 8
Biodegradation and aneurysm formation in umbilical vein grafts . Observations and a realistic strategy; Dardik H et al.; In a series of 756 glutaraldehyde-stabilized umbilical vein grafts implanted over a 7 1/2-year period, aneurysms were identified in seven cases . The earliest aneurysm was seen at 31 months after implantation and the remainder between 43 and 79 months after surgery . Corrective surgery was performed in five cases and succeeded in four . Although definite mechanisms have not been identified, mechanical fatigue, reversal of aldehyde crosslinks, and immunologic factors may be operative . The pathologic changes include: (1) actual dilation of both graft and mesh with or without intraluminal thrombus and, (2) maintenance of graft diameter with erosion of the umbilical vein and polyester mesh rupture leading to perigraft hematoma and false aneurysm formation . Microscopic examination and infrared spectral analysis confirmed the presence of host-contributed lipid in some specimens . Although this is a low incidence of aneurysm formation, umbilical vein grafts should be selected primarily for patients with limited life expectancy or for whom alternative materials with comparable or superior patency rates are not available or acceptable . Periodic angiography, particularly after 3 or 4 years, is recommended as a routine part of follow-up examinations . Improved graft materials and control of host environmental factors are potential means to reduce the noted degradation.

Polim Med, 1984, 14(1-4), 37 - 54
{Polymer fibers in surgery . II}; Privalova LG et al.; Polyamide fibres were one of the first synthetic fibres to be widely used in surgery . They are durable, elastic, abrasion- and deformation-resistant, and withstand the biological action of chemical agents . Moreover, they have small susceptability to moisture sorption and large values of percentage elongation . In surgery polycaproamide fibres (PKA) are usually used--capron, nylon-6, perlon, stylon, sylon and others, they can be easily and reliably sterilized, do not facilitate infection spreading in the thread, and are relatively well resorbed . The fibres were used as surgical threads and nets, vascular prostheses, woven and knitted fabric in hernia treatment, diaphragm injuries, strengthening the diaphragm seam, an other reconstruction operations . In most cases the tissues adjoining the implant react moderately . It is suggested that porous materials should be used as implants, so that they overgrow with tissue, and gradually undergo biodestruction . Depending on the kind and structure of fibres, and specific tissue properties, the biodegradation period varies from 2-3 weeks to 2-3 years . According to the authors this depends on polymer breakdown by means of hydrolysis . In the paper conditions of fibre modifications are shown in order to improve their usability in therapy . Quantitative changes in biodestruction of various kinds of polycaproamide threads in the organism are described . It is stressed that polyundecanamide fibres (undecan, nylon-11) are less applicable in surgery than polyhexametyleno-2-amide ones (anid, nylon-6,6) . Through of some favourable properties, polyamide fibres have a very restricted application in surgery; their surface is rough, which makes surgical binding difficult, thin threads, last shortly in tissues, lose elasticity, get brittle and fragile . The period of their biodestruction is rather short . In conclusion it is stated that polyamide fibres are not suitable for durable prostheses.

Arch Orthop Trauma Surg, 1984, 103(3), 145 - 51
Histological results with cement-free implanted hip joint sockets of polyethylene; Remagen W et al.; The histological appearance of the implant-bone boundary in eight preparations from seven deceased patients in whom a polyethylene acetabulum socket had been inserted without cement between 3 weeks and 3 years previously is described . In all cases, a good or excellent clinical result had been present up to death . All sockets were firmly anchored macroscopically in the bone of the acetabulum . Three zones were defined in accordance with the mechanical strain on the surface of the cup: (a) zone of compression; (b) zone of transition in which mainly shear forces act; and (c) zone of decompression, which corresponds to the region below the "equator." It was noticeable that a layer of connective tissue separated the implant from the bone over almost the entire surface . This layer was very thin in the region of the pressure transfer layer, and thicker in the decompression zone . At sites at which pressure and shear forces act a fibrocartilaginous tissue was found, and the "subchondral" bone was only occasionally in direct contact with the polyethylene surface . At some sites, but above all in the region of the compression zone, very tiny particles that were birefringent in polarized light were found . Either these derive from very fine grindings from the prosthesis surface or they are to be interpreted as a result of "biodegradation" of the polyethylene . This observation permits the conclusion that the biocompatibility of the implant can be improved further by coating the polyethylene surface.

Basic Life Sci, 1984, 28, 117 - 35
Plasmid-mediated biodegradative fate of monohalogenated biphenyls in facultatively anaerobic sediments; Sayler GS et al.; The results of these studies have demonstrated that model PCB substrates can be mineralized by indigenous microbial population in contaminated sediments . This catabolic function can be rate limited at the microenvironmental level by physical-chemical processes such as physical partitioning and accumulation . At the biochemical level, this catabolic function is determined by the existence of plasmid borne genes that, under laboratory conditions, can be maintained and expressed in pure or mixed culture . Numerous limitations are encountered in establishing the significance of these biodegradative bacteria and the catabolic plasmids at the environmental level . Relatively little information is available concerning frequencies and stability of the bacteria or the plasmid encoded genes within the community . There is no information on the incompatibility grouping of the isolated plasmid relative to other plasmids maintained within the populations . Such factors will influence the development of gene screening techniques to monitor gene frequency distributions in the sediment community . Although mineralization of 4CBP was observed under moderately reducing conditions, it remains suspect that transient or trace levels of dissolved oxygen may have permitted conventional aerobic metabolism of the substrate . If this is true, demonstrating anaerobic metabolism of environmental contaminants will require strict and tedious cultivation under highly reduced conditions (approximately-300 mV) . Large deletions of cryptic DNA observed under laboratory conditions may affect bacterial survival and gene maintenance and transfer under environmental conditions . Little information exists on regulation of catabolic activity of selective pressures required to maintain the degradative genes under environmental conditions . Such limitation encountered in these studies are shared by virtually all attempts to utilize genetically manipulated bacteria or newly isolated strains and plasmids . Perhaps the fundamental question is whether the catabolic genes are maintained and expressed within the community rather than whether the host bacterium can survive in the environment.

Appl Biochem Biotechnol, 1984, 10, 41 - 56
Enzyme-albumin polymers . New approaches to the use of enzymes in medicine; Poznansky MJ; The widespread use of enzymes as drugs or therapeutic agents has been limited by (a) enzyme availability, (b) biodegradation of administered enzyme, (c) immunogenecity of the enzyme as a foreign protein, and (d) accessibility of the enzyme to the appropriate site of action . It has become obvious that due to these limitations, the administration of free or native enzyme is not likely to be effective . Various mechanisms of protecting or packaging enzymes to offset some of these drawbacks have been described . We have been successful in producing conjugates of a number of different enzymes with a molar excess of homologous albumin . The resulting enzyme-albumin complex is resistant to proteolytic and heat inactivation and is apparently non-immunogenic . Using specific ligands crosslinked to the enzyme-albumin conjugate we have been able to target these conjugates to specific receptor sites and specific tissues . Ligands including cell surface-recognizing antibodies and hormones such as insulin have been used . These approaches offer new possibilities for the increased use of enzymes in medicine.

J Microencapsul, 1984 Jan-Mar, 1(1), 21 - 5
Chemoembolization: principles and perspectives; Madoule P et al.; Chemoembolization is the injection of active-principle-bearing microparticles via selective catheterization . The authors discuss the advantages and the possibilities of this method in relation to selective catheterization and to the various time periods required for microparticle biodegradation and the kinetics of drug release . Particular attention is paid to intra-arterial chemoperfusion, chemoembolization and chemoinfusion with microparticles.

Drug Metab Dispos, 1984 Jan-Feb, 12(1), 98 - 105
Effects of exposure concentrations on distribution of halothane metabolites in the body; Fiserova-Bergerova V et al.; The effect of exposure concentration on halothane metabolism was studied in rats exposed to subanesthetic concentrations of halothane in air . Concentrations of halothane, total nonvolatile fluorine, and volatile metabolites (CF3CH2Cl and CF2 = CHCl) were determined in liver, kidneys, muscles, and brains excised at the end of a 3-hr exposure . It was observed that concentrations of all halothane metabolites in tissues rose less than exposure concentrations, that nonvolatile fluorine was present in all tissues in approximately the same concentrations, and that concentrations of volatile metabolites in liver were much higher than in any other tissues . A simulation model was used to support the following conclusions . Metabolism of halothane by all metabolic pathways is flow limited at small exposure concentrations and is capacity limited at high exposure concentrations . Volatile metabolites formed in livers are efficiently removed from circulation by pulmonary clearance, but trifluoroacetic acid is accumulated in the body . Halothane is most susceptible to biodegradation to trifluoroacetic acid, but this pathway is saturated at very small exposure concentrations . Susceptibility to biodegradation of volatile metabolites is small, but the pathways are not saturated even at anesthetic concentrations . The contribution of each of the three metabolites to total metabolic clearance depends on exposure concentrations . Trifluoroacetic acid was the major metabolite during exposure to small halothane concentrations; formation of more toxic, volatile metabolites increased during exposure to high concentrations . Postmortem formation of metabolites was studied in order to prevent its interference with tissue analysis . The method for determination of volatile metabolites is described.

Appl Environ Microbiol, 1983 Nov, 46(5), 1024 - 31
Biodegradation and photolysis of pentachlorophenol in artificial freshwater streams; Pignatello JJ et al.; The biodegradation, photolysis, and adsorption of pentachlorophenol (PCP) in outdoor, aquatic environments were examined with man-made channels built by the U.S . Environmental Protection Agency at a field station on the Mississippi River near Monticello, Minn . Four channels were used, each channel being approximately 520 m long and receiving river water that flowed through the channels for about 10 h before reentering the river . The channels were dosed continuously during the summer of 1982 with various concentrations of PCP (approximately 0, 48, 144, and 432 micrograms/liter) . We monitored the biotic and abiotic degradation of PCP in these channels for approximately 16 weeks . Photolysis of PCP was rapid at the water surface, but greatly attenuated with depth . Depending on sunlight conditions, photolysis accounted for a 5 to 28% decline in initial PCP concentration . Adsorption of PCP by sediment and uptake by biota accounted for less than 15% and probably less than 5% in unacclimated water . Microbial degradation of PCP became significant about 3 weeks after the initiation of dosing and eventually became the primary mechanism of PCP removal, accounting for a 26 to 46% (dose-dependent) decline in initial PCP . Most of the PCP-mineralizing microorganisms that developed in the channels were either attached to surfaces (e.g., rocks and macrophytes) or associated with surface sediments . Total bacterial numbers (direct microscopic counts) in the various channels were not affected significantly by PCP concentrations of micrograms per liter . Numerous strains of bacteria able to grow at the expense of PCP were isolated from the adapted channels . The experiments reported here will help predict the responses of flowing aquatic ecosystems to contamination by biocides such as pentachlorophenol.

Fed Proc, 1983 Nov, 42(14), 3128 - 31
Leukocyte recognition and metabolism of leukotrienes; Goetzl EJ; The lipoxygenation of arachidonic acid in many different types of cells generates diverse mediators of hypersensitivity and inflammation . The leukotrienes represent one such family of mediators, which exert potent effects on smooth muscle, the microcirculation, and leukocytes . Leukocytes express distinct subsets of receptors for different leukotrienes . Transpeptidatic, peptidolytic, oxidative, and peroxidative pathways of leukocytes contribute substantially to the interconversion and biodegradation of leukotrienes . The 5-lipoxygenation of endogenous arachidonic acid appears to be a critical prerequisite for the activation of the function of leukocytes and some other cells . Natural and pharmacological inhibitors of 5-lipoxygenation in T lymphocytes noncytotoxically suppress the migration and transformation of the lymphocytes in response to antigens and mitogens . Lipoxygenase products of arachidonic acid thus fulfill important roles both as extracellular mediators and as functional intracellular constituents.

Ital J Orthop Traumatol, 1983 Sep, 9(3), 377 - 86
Metallic debris arising from prosthetic abrasion: investigation of biodegradation of the materials and physiopathology of the bone; Portigliatti Barbos M et al.; The authors investigated the tissue around a failed knee prosthesis which had a metal-on-metal bearing made of chromium-cobalt-molybdenum alloy . Histological examination and the quantitative analysis of metallic particles found in the bone marrow (by fluorescent spectrometry and laser microsound) provided a detailed picture of the quantity, nature and distribution of the wear debris . The type and nature of the tissue response to the presence of the metal particles was determined by fluorescent microscopy and microradiography.

Appl Environ Microbiol, 1983 Sep, 46(3), 661 - 5
Absence of microbial mineralization of lignin in anaerobic enrichment cultures; Odier E et al.; The existence of anaerobic biodegradation of lignin was examined in mixed microflora . Egyptian soil samples, in which rapid mineralization of organic matter takes place in the presence of an important anaerobic microflora, were used to obtain the anaerobic enrichment cultures for this study . Specifically, 14CO2 or {14C}lignin wood was used to investigate the release of labeled gaseous or soluble degradation products of lignin in microbial cultures . No conversion of 14C-labeled lignin to 14CO2 or 14CH4 was observed after 6 months of incubation at 30 degrees C in anaerobic conditions with or without NO3- . A small increase in soluble radioactivity was observed in certain cultures, but it could not be related to the release of catabolic products during the anaerobic biodegradation of lignin.

Can J Microbiol, 1983 Sep, 29(9), 1087 - 91
Factors influencing the inhibition of aflatoxin production in corn by Aspergillus niger; Horn BW et al.; Aspergillus niger, a mold commonly associated with Aspergillus flavus in damaged corn, interferes with the production of aflatoxin when grown with A . flavus on autoclaved corn . The pH of corn-meal disks was adjusted using NaOH-HCl, citric acid-sodium citrate, or a water extract of A . niger fermented corn . Aflatoxin formation was completely inhibited below pH 2.8-3.0, irrespective of the system used for pH adjustment . When grown in association with A . flavus NRRL 6432 on autoclaved corn kernels, A . niger NRRL 6411 lowered substrate pH sufficiently to suppress aflatoxin production . The biodegradation of aflatoxin B1 or its conversion to aflatoxin B2a were eliminated as potential mechanisms by which A . niger reduces aflatoxin contamination . A water extract of corn kernels fermented with A . niger caused an additional inhibition of aflatoxin formation apart from the effects of pH.

Proc Natl Acad Sci U S A, 1983 Sep, 80(17), 5181 - 4
Regulation of polyamine biosynthesis in Escherichia coli by basic proteins; Heller JS et al.; In Escherichia coli, the biosynthetic ornithine and arginine decarboxylases (EC 4.1.1.17 and 4.1.1.19, respectively) are responsible for the biosynthesis of polyamines from ornithine and arginine, respectively . When E . coli cells are grown in the presence of increasing amounts of polyamines, a progressive increase in the amount of antizyme 1 and antizyme 2 occurs . The amino acid compositions of antizymes 1 and 2 show them to be basic proteins; antizyme 1 has an amino acid composition similar to that of the E . coli histone-like protein HU and of the eukaryotic histone H2B; antizyme 2 is characterized by an unusually high arginine content . We find these proteins to be specific inhibitors of both the biosynthetic ornithine decarboxylase and the biosynthetic arginine decarboxylase . They do not inhibit the corresponding biodegradative ornithine and arginine decarboxylases, nor do they inhibit lysine decarboxylase or S-adenosylmethionine decarboxylase . These properties of the antizymes favor their function in the regulation of polyamine biosynthesis in E . coli . The ability of the purified antizymes to inhibit the ornithine and arginine decarboxylases is stabilized in acidic buffers and is lost upon prolonged exposure to solutions at neutral or basic pH.

J Biomed Mater Res, 1983 Sep, 17(5), 769 - 84
Biodegradation behavior of various calcium phosphate materials in bone tissue; Klein CP et al.; In order to study the biodegradation behavior of calcium phosphate materials, cylinders of standard size were implanted in the tibiae of rabbits . Material parameters were stoichiometry (hydroxyapatite with a Ca/P ratio of 1.67 versus tricalcium phosphate with a Ca/P ratio of 1.50), crystallographic structure (apatite versus beta-whitlockite), microporosity, and macroporosity . The extent of biodegradation was evaluated by radiography, light and fluorescence microscopy, microradiography, and porosity measurements . All calcium phosphate materials were biocompatible in bone tissue . Hydroxyapatite ceramics had a higher osteogenic potential than beta-whitlockite materials . Depending on their porosities, sintered tricalciumphosphate (beta-whitlockite) materials were more or less biodegradable, in contrast to sintered hydroxyapatite materials, which showed no detectable resorption over a period of 9 months of implantation.

Life Sci, 1983 Aug 29, 33(9), 835 - 40
Met-enkephalin binding to opiate receptors is not functionally coupled to biodegradation; Nagy A et al.; Using synaptosomal rat brain membranes, the degradation of Met-enkephalin in both free and receptor-bound form was measured, together with the dissociation of Met-enkephalin from the receptors . The results show that the degradation rate of initially receptor-bound Met-enkephalin is significantly smaller than either the rate of dissociation from the receptors or that of the degradation of free Met-enkephalin . These data suggest that intact Met-enkephalin dissociates from the receptors and then it becomes a target for the same membrane-associated peptidases that split free Met-enkephalin . This view is supported by the good fitness of the measured degradation of initially receptor-bound Met-enkephalin to the predicted degradation curve calculated from the dissociation rate of receptor-bound Met-enkephalin and the degradation rate of free Met-enkephalin.

Biochem Biophys Res Commun, 1983 Aug 12, 114(3), 1077 - 83
An extracellular H2O2-requiring enzyme preparation involved in lignin biodegradation by the white rot basidiomycete Phanerochaete chrysosporium; Glenn JK et al.; An H2O2-requiring enzyme system was found in the extracellular medium of ligninolytic cultures of Phanerochaete chrysosporium . The enzyme system generated ethylene from 2-keto-4-thiomethyl butyric acid (KTBA), and oxidized a variety of lignin model compounds including the diarylpropane 1-(4'-ethoxy-3'-methoxyphenyl) 1,3-dihydroxy-2-(4"-methoxyphenyl)propane (I), a beta-ether dimer 1-(4'-ethoxy-3'-methoxyphenyl)glycerol-beta-guaiacyl ether (IV) and an olefin 1-(4'-ethoxy-3'-methoxyphenyl)1,2-propene (VI) . The products found were equivalent to the metabolic products previously isolated from intact ligninolytic cultures . In addition, the enzyme system partially degraded 14C-ring labeled lignin . The enzyme was not found in high nitrogen (N) cultures, nor in cultures of a ligninolytic mutant strain which is incapable of metabolizing lignin.

J Bacteriol, 1983 Aug, 155(2), 586 - 92
Synthesis of biodegradative threonine dehydratase in Escherichia coli: role of amino acids, electron acceptors, and certain intermediary metabolites; Hobert EH et al.; The specific activity of inducible biodegradative threonine dehydratase (EC 4.2.1.16) in Escherichia coli K-12 increased significantly when the standard tryptone-yeast extract medium or a synthetic mixture of 18 L-amino acids was supplemented with 10 mM KNO3 or 50 mM fumarate and with 4 mM cyclic AMP . In absolute terms, almost four times as much enzyme was produced in the amino acid medium as in the tryptone-yeast extract medium . Enzyme induction in the amino acid medium was sensitive to catabolite repression by glucose, gluconate, glycerol, and pyruvate . An analysis of amino acid requirements for enzyme induction showed that a combination of only four amino acids, threonine, serine, valine, and isoleucine, produced high levels of threonine dehydratase provided that both fumarate and cyclic AMP were present . Immunochemical data revealed that the enzyme synthesized in the presence of these four amino acids was indistinguishable from that produced in the tryptone-yeast extract or the medium with 18 amino acids . We interpret these results to mean that not the amino acids themselves but some metabolites derived anaerobically in reactions involving an electron acceptor may function as putative regulatory molecule(s) in the anaerobic induction of this enzyme.

Dev Biol, 1983 Jul, 98(1), 182 - 6
Metabolism of sulfogalactosyl glycerolipids in the myelinating mouse brain; Burkart T et al.; The in vivo metabolism of sulfogalactosyl glycerolipids (SGG) was studied in the cerebrum and cerebellum of developing mice after intraperitoneal injection of {35S}sulfate . After correction for the specific radioactivity changes of blood sulfate the quantitative rates of biosynthesis and biodegradation of this lipid could be determined . In addition, the net accumulation of SGG was measured . Throughout development the rates of SGG biosynthesis and net accumulation were higher in the cerebellum than in the cerebrum . The developmental patterns of SGG net synthesis in both parts of the brain were closely related to those observed earlier for sulfatide . During development the rate of SGG biosynthesis in both parts of the brain showed a peak earlier than that of sulfatide (at 14 days versus 20 days) . The in vivo patterns of SGG degradation followed those of biosynthesis in the cerebrum and cerebellum . During postnatal development 40 to 80% of the daily synthesized SGG disappeared within 24 hr, suggesting that degradation may also be involved in the regulation of SGG net synthesis during myelination, as previously indicated for sulfatide.

Biomaterials, 1983 Jul, 4(3), 201 - 4
Structural peculiarities of block copolyurethanes with peptide links as rigid block extenders; Lipatova TE et al.; X-ray crystal analysis was performed on block copolyurethanes with peptide links as rigid block extenders . The increase in peptide link length was shown to improve the microphase separation of flexible and rigid segments . The influence of the isocyanate nature on phase separation conditions in the block copolyurethanes studied was established . The correlation between mechanical and temperature characteristics and peculiarities of the microphase structure was found . The latter seems especially important because of the dependence existing between the biodegradation tendency of the polyurethanes and their supermolecular organization.

Appl Environ Microbiol, 1983 Jul, 46(1), 50 - 4
Anaerobic biodegradation of phenolic compounds in digested sludge; Boyd SA et al.; We examined the anaerobic degradation of phenol and the ortho, meta, and para isomers of chlorophenol, methoxyphenol, methylphenol (cresol), and nitrophenol in anaerobic sewage sludge diluted to 10% in a mineral salts medium . Of the 12 monosubstituted phenols studied, only p-chlorophenol and o-cresol were not significantly degraded during an 8-week incubation period . The phenol compounds degraded and the time required for complete substrate disappearance (in weeks) were: phenol (2), o-chlorophenol (3), m-chlorophenol (7), o-methoxyphenol (2), m- and p-methoxyphenol (1), m-cresol (7), p-cresol (3), and o-, m-, and p-nitrophenol (1) . Complete mineralization of phenol, o-chlorophenol, m-cresol, p-cresol, o-nitrophenol, p-nitrophenol, and o-, m-, and p-methoxyphenol was observed . In general, the presence of Cl and NO2 groups on phenols inhibited methane production . Elimination or transformation of these substituents was accompanied by increased methane production, o-Chlorophenol was metabolized to phenol, which indicated that dechlorination was the initial degradation step . The methoxyphenols were transformed to the corresponding dihydroxybenzene compounds, which were subsequently mineralized.

J Dent Res, 1983 Jun, 62(6), 733 - 7
The development of a novel tooth-root implant material; El Basty MA et al.; Polyacrylic acid-alumina composites have been developed in this laboratory and were found to be biocompatible and resistant to biodegradation . These composites can be designed to apply a predetermined pressure on the bone interface which was found beneficial for stimulation of new bone formation and increased bone densification at the implant interface . Optimization of the physical and mechanical properties is presented, and a brief summary of the subcutaneous and oral implantation is reported.

Ophthalmology, 1983 Apr, 90(4), 301 - 10
Quality control, and changing indications for lens implantation . The Seventh Binkhorst Medal Lecture-1982; Drews RC; A total of 776 specimens yielded significant data on quality control and manufacturing defects in lens implants and on the biodegradation of lens implant and suture materials . Improved quality and an understanding of durability of materials in vivo has permitted wider safe use of intraocular lenses.

Chest, 1983 Apr, 83(4), 607 - 11
Glutaraldehyde-preserved porcine bioprosthesis . Factors affecting performance as determined by pathologic studies; Valente M et al.; The causes of porcine valve failure were evaluated pathologically in 129 bioprostheses (BP) removed at surgery or necropsy . Fifty-one BP had been in place for less than two months (early explants); most of the complications of this group were observed in the mitral position: left ventricular outflow obstruction (43 percent), thrombosis (23.5 percent), myocardial dysruption (20 percent), cardiac rupture (10 percent), and perivalvular leak (3.5 percent) . Among the 78 explants in place for more than two months (late explants), 66 had evidence of dysfunction . Calcification was the leading cause of failure (46 percent), followed by thrombosis (17 percent), endocarditis (12 percent), fibrous tissue overgrowth (10 percent), perivalvular leak (9 percent), and primary cusp tears (6 percent) . Calcific degeneration is a hallmark of the phenomenon of biodegradation, and experimental animal models are encouraged since they may represent the clue to preventing calcification and therefore enhancing performance and durability of the porcine BP.

Biol Reprod, 1983 Feb, 28(1), 186 - 95
Poly(DL-lactide-co-glycolide)/norethisterone microcapsules: an injectable biodegradable contraceptive; Beck LR et al.; Microcapsules made from a biocompatible, biodegradable polymeric excipient, poly(DL-lactide-co-glycolide) (DL-PLGA) that contained 22 weight percent (wt %) norethisterone (NET), were prepared by a solvent-evaporation microencapsulation process . The effects of changing both the lactide-to-glycolide ratio of the DL-PLGA and the size of the microcapsules on the rate of NET release and the rate of excipient biodegradation were determined in vivo . NET release rates were determined in baboons after injecting the microcapsule formulations intramuscularly . Serum samples obtained at various times following treatment were analyzed for NET, progesterone, and estrogen by radioimmunoassay (RIA) . Biodegradation kinetics were determined by injecting NET microcapsules made from radiolabeled DL-PLGA intramuscularly into the hind legs of rats . Residual radioactivity at the injection site was determined at various times after treatment by combustion analysis of the muscle tissue . Changing the ratio of the comonomers to include more glycolide (DL-lactide:glycolide-96:4, 92:8, 87:13, 74:26) increased the rate of NET release and accelerated the biodegradation of the copolymer excipient . Decreasing the size of the microcapsules increased the rate of NET release . On the basis of these studies a NET microcapsule formulation has been identified for clinical testing which releases NET for 3 months and biodegrades completely within 6 months.

Appl Environ Microbiol, 1983 Jan, 45(1), 103 - 9
Influence of spatial and temporal variations on organic pollutant biodegradation rates in an estuarine environment; Bartholomew GW et al.; The influence of spatial and temporal environmental variations on rates of organic pollutant biodegradation were assessed by using heterotrophic uptake kinetics . These studies were conducted at three sites, representing the gradient from freshwater to estuarine to marine systems . Of the compounds tested, total uptake Vmax rates decreased in the order of nitrilotriacetic acid, m-cresol, chlorobenzene, and 1,2,4-trichlorobenzene . In general, the freshwater site exhibited the highest uptake rates, with somewhat lower rates at the estuarine site . Rates at the marine site were much lower than at the other sites, except during the winter . Metabolic rates at both the freshwater and estuarine areas were significantly decreased during periods of low water temperature . Rates at the marine site were relatively uniform throughout the year . Linear regression analysis was used to compare m-cresol biodegradation rates to characteristics of the microbial community, which included direct microscopic counts, CFU counts, and cellular incorporation of amino acids . The observed rates did not consistently correlate well with any of the measured characteristics of the microbial community.

Br J Anaesth, 1983, 55 Suppl 1, 3S - 10S
Atracurium: conception and inception; Stenlake JB et al.; The rationale underlying the design of atracurium, a bis-quaternary ammonium neuromuscular blocking agent which incorporates the Hofmann elimination as a novel biodegradation pathway, is described . Destruction in vivo, of the bis-quaternary structure essential for neuromuscular blocking activity, by the combination of Hofmann elimination and a parallel ester hydrolysis leads to innocuous breakdown products that are without neuromuscular or cardiovascular effects and to a time-course of action which is unaffected by the level of plasma esterase activity, renal or hepatic function.

Trans Am Soc Artif Intern Organs, 1983, 29, 307 - 13
Peripheral nerve repair with bioresorbable prosthesis; Nyilas E et al.; Using the transected sciatic nerve model in adult mice, regeneration of a large bundle of axons organized into the form of a nerve with myelinated and unmyelinated axons, Schwann cells, fibroblasts, collagen, blood vessels, and connective tissue sheaths has been achieved with bioresorbable microtubular guidance channels over gaps of 5 mm in nonimmobilized animals . After 4-6 wks postoperatively, the regenerated nerve cable contains on the order of 40% as many myelinated axons as were measured in the proximal nerve stumps . With the channels used so far in this model, regenerating axons pass into the distal stump in about 3-6 wks postoperatively . The guidance channels used consist of synthetic polyesters and/or polyester composites including glycolic and lactic acid polymers, and polyesters derived from Krebs Cycle dicarboxylic acids . Inflammatory response to these materials has been minimal . Biodegradation/resorption rates can be controlled so as to be compatible with axon growth rates.

Ann Parasitol Hum Comp, 1983, 58(4), 353 - 9
{Possibilities of using amphoteric surface agents in the campaign against the agents of schistosomiasis transmission}; Combes C et al.; Among the chemicals which might be used against the larvas of Schistosoma, some surface active substances show some high activity at very low concentrations (0,1-5 ppm) against the miracidiums and the cercariae . The laurylamidopropylbetain has shown out of a group of products which were tested, a very high activity by lowering considerably the infection by the larvas of the hosts, like molluscs and mice, which were in contact with them . After a serie of tests made in Nigeria, these products showed a satisfactory remanence in tropical waters, in spite of the biodegradation and the adsorption on the suspended particles . It was faced to put that betain into soaps at a concentration of 5% which will permit to renew constantly the active product and which will reduce heavily any infection.

Ecol Dis, 1983, 2(4), 295 - 308
Endemic goiter in western Colombia; Gaitan E; Goiter continues to occur in some areas of western Colombia despite iodine supplementation for 30 years . In 1973-1977, an average goiter prevalence of 15% (range 1-42%) still persisted among schoolchildren of 41 localities . Significant relationships were found between goiter prevalence and both the geological composition of watersheds and bacterial contamination of water supplies . Together, these associations account for 80% of the observed variation in goiter prevalence . The presence of sedimentary rocks rich in organic matter (coals, shales, etc.) was the best indicator of disease . The second best indicator, presence of K . pneumoniae in the water source, was associated with lower goiter prevalence but, as in other investigations, contamination of the pipeline system (households and schools) with gram-negative bacteria was associated with higher disease rates . Thus, epidemiological evidence indicates a cause-effect relationship between sources of drinking water and the persistence and development of goiter in this part of the world . Furthermore, identification of resorcinol, phthalate esters, and sulfur-bearing organic compounds, possibly aliphatic disulfides, in the water supplying the endemic goiter district of Candelaria town in western Colombia adds experimental support to this hypothesis . Resorcinol is derived from coal and humic substances, high molecular weight complex polymeric organic compounds present in sedimentary rocks, soils and water . Resorcinol is goitrogenic in man and experimental animals . Phthalate esters, also related to humic materials, undergo biodegradation by gram-negative bacteria with production of intermediate metabolites possessing antithyroid activity . Like phthalates and resorcinol, organic disulfides have also been identified as water contaminants in other parts of the world, and are known to be potent antithyroid compounds . The goitrogenic effect of organic and bacterial pollutants in water supplies is more pronounced in segments of the population with dietary iodine deficiency--as seen prior to the iodine prophylaxis program--and/or poor socio-economic conditions . Studies are underway to provide both insight into the biogeochemical cycle of water-borne goitrogens and knowledge essential to the development of rapid, inexpensive, and precise methods for detecting and quantifying the offending agents, as well as devising effective sanitation techniques for their inactivation and/or elimination . The impact of such measures will be determined on goiter prevalence and other parameters of health and nutrition of the communities under study.(ABSTRACT TRUNCATED AT 400 WORDS)

Biomater Med Devices Artif Organs, 1983-84, 11(4), 271 - 80
Problems and challenges of biomaterials in cardiovascular applications: a status report; Bruck SD; Biomaterials used as implants and in various devices must exhibit long-term (years) compatibility with the physiological environment, including blood, and additionally must also remain stable to perform mechanical functions, excepting applications where biodegradation is required . This paper focuses on problems and challenges of polymeric materials in contact with blood in the following categories: (1) artificial heart valves, (2) cardiovascular assist devices and artificial hearts, (3) vascular prostheses, and (4) the biological evaluation of materials prior to their human use, especially with respect to species related hematological differences of experimental animals . Besides thrombosis (which is the most obvious consequence of incompatibility), the calcification of chemically treated tissue prostheses as well as synthetic elastomers used in many cardiovascular devices is discussed in terms of biochemical and physico-chemical parameters together with its significance in long-term (years) implant applications . Complement activation brought about by contact of blood with foreign surfaces has received less than deserved attention in the evaluation of biomaterials and devices, despite the potentially serious problems . Relative ignorance in selecting appropriate animals for the biological evaluation of biomaterials whose hematological profiles and behavior of platelets, red and white cells to trauma and response to foreign surfaces differ decisively from those of humans, often leads to less than meaningful predictions for eventual clinical uses . The state-of-art realities are examined in conjunction with medical, societal, ethical, and economic boundaries.

Ukr Biokhim Zh, 1983, 55(3), 311 - 7
{Clinico-experimental study of the possibility of the use of immobilized enzymes for local thrombolysis and thromboformation}; Smirnov VN et al.; Fibrinolysin immobilized by a solid polysaccharide carrier capable of controllable biodegradation is shown to exert a local effective thrombolyzing action . Certain results of clinical studies of immobilized streptase (streptodecase) are presented . They show essential advantages of the new preparation over the known native enzymes . Experiments with animals show that the immobilized thrombin may be applied in therapeutic embolization for the hemorrhage cessation.

J Environ Sci Health B, 1983, 18(1), 147 - 72
Biochemical toxicology of lindane and its analogs; Nakajima M; The inhibitory potencies of BHC isomers against Na+-K+- ATPase, yeast growth and nerve conduction of the American cockroach were determined . The insecticidal and neuroexcitatory activities of a number of analogs with the same configuration as lindane in which some chlorine atoms had been replaced by other substituents were also examined against American cockroaches . The structure-activity relationships and the mode of action of lindane and its analogs were discussed . Their metabolic fate was studied extensively in vivo as well as in vitro . The critical step in the biodegradation of lindane is the cleavage of C-H bonds which we found by utilizing the isotope effect of hexadeuterated lindane.

FEBS Lett, 1982 Dec 13, 150(1), 211 - 3
Inactivation of spermidine N1-acetyltransferase with alkaline phosphatase; Matsui I et al.; Spermidine N1-acetyltransferase in an extract from phytohemagglutinin-stimulated bovine lymphocytes was inactivated by preincubation with alkaline phosphatase . Inactivation of the acetylase with the phosphatase was totally inhibited by addition of pyrophosphate . These results suggest that spermidine N1-acetyltransferase, the rate-limiting enzyme in the biodegradative pathway of polyamines, is inactivated by dephosphorylation . A similar effect of alkaline phosphatase on the acetylase in an extract from Escherichia coli was also observed . The acetylase has a rapid rate of turnover and the rapid loss of the enzyme activity may be to some extent regulated by the covalent modification.

Mikrobiologiia, 1982 Nov-Dec, 51(6), 1005 - 7
{Aromatic hydrocarbons as enzyme inducers of cleavage of the aromatic ring in Candida guilliermondii}; Ismailov NM; Monocyclic and dicyclic aromatic hydrocarbons, toluene and 2-methylnaphthalene, can induce pyrocatechate-1,2-oxygenase in Candida guilliermondii BKM Y-916 cells . The enzyme is active at pH 7.0 . The culture oxidizes toluene via benzoic acid by ortho-cleavage . The results indicate that Candida as an ecologo-trophic group of microorganisms can be involved, along with bacteria, in biodegradation of various aromatic hydrocarbons.

J Biol Chem, 1982 Oct 10, 257(19), 11455 - 62
The involvement of hydroxyl radical derived from hydrogen peroxide in lignin degradation by the white rot fungus Phanerochaete chrysosporium; Forney LJ et al.; The possible involvement of hydrogen peroxide (H2O2)-derived hydroxyl radical (.OH) in lignin degradation ({14C}lignin leads to 14CO2) by Phanerochaete chrysosporium was investigated . When P . chrysosporium was grown in low nitrogen medium (2.4 mM N), an increase in the specific activity for H2O2 production in cell extracts was observed to coincide with the appearance of ligninolytic activity and both activities appeared after the culture entered stationary phase . The production of .OH in ligninolytic cultures of P . chrysosporium was demonstrated by alpha-keto-gamma-methiolbutyric acid-dependent formation of ethylene . Hydrogen peroxide-dependent .OH formation was also shown in cell extracts of ligninolytic cultures . The radical species was demonstrated to be .OH by the .OH-dependent hydroxylation of p-hydroxybenzoic acid to form protocatechuic acid and by using 5,5-dimethyl-1-pyrroline-N-oxide and detecting the production of the nitroxide radical of 5,5-dimethyl-1-pyrroline-N-oxide by EPR . These reactions were inhibited by .OH-scavenging agents and were stimulated when azide was added to inhibit endogenous catalase . Lignin degradation by P . chrysosporium was markedly suppressed in the presence of the .OH-scavenging agents mannitol, benzoate, and the nonspecific radical scavenging agent butylated hydroxytoluene . The above results indicate that .OH derived from H2O2 is involved in lignin biodegradation by P . chrysosporium.

Arch Pathol Lab Med, 1982 Oct, 106(10), 490 - 6
Structural changes of glutaraldehyde- treated porcine bioprosthetic valves; Camilleri JP et al.; Gross anatomic, histologic, and transmission and scanning electron microscopic observations were made of 29 bioprosthetic valves that had been implanted in patients for up to 115 months . On the basis of these morphologic data, no significant evidence of tissue rejection was seen . However, the durability of these valve bioprostheses is still questionable . Our observation primarily emphasize three factors: (1) disruption of the endothelial cell barrier and the lack of significant host endothelialization even 115 months after transplantation; (2) increased permeability that eased diffusion of circulating host plasma proteins into valve tissue, and increased activity of infiltration processes, eg . calcification and lipid accumulation; and (3) biodegradation of the collagen framework . Each of these factors may contribute further to valve dysfunction . Development of an intimal fibrous sheath seems to occur in porcine bioprostheses that have been implanted for the longest periods of time, but the rate of host tissue ingrowth varies.

Hum Pathol, 1982 Oct, 13(10), 878 - 81
IUDs, inflammation, and infection: assessment after two decades of IUD use; Schmidt WA; PIP: In the 1950s social and technological changes allowed experimental use of an inert plastic IUD which was successful and regarded as safe . The devices were pliable, chemically inert, sterilizable, disposable, and equipped with a small inserter so that cervical dilation was not needed for insertion . But many IUDs were withdrawn because they were found to cause endometritis and provide poor protection against pregnancy . In the 1970s there were cases of serious inflammatory and infectious diseases with pelvic inflammatory disease (PID) the most common . The Dalkon Shield has been associated with midtrimester septic abortions and with unilateral actinomycotic tube-ovarian abscesses and there is evidence to support a chemically caused IUD-related endometritis in the moderate inflammation associated with IUDs containing copper and with the Majzlin spring . The most common factor among IUD users with Actinomycetales infection is not the type of IUD but the duration of use; almost 85% of cases were in women who had worn IUDs over 3 years . Also the likelihood of an ectopic pregnancy is almost 3 times greater for longterm IUD users . It is hypothesized that with time the IUD is capable of inducing changes that can lead to infection and that changes can occur to the IUD itself . A surface coating on the IUD and the tail has been found which is composed of mucoid and cellular elements which consist of an inflammatory response; the IUD then becomes recognized as a foreign body to the host and may contribute to the development of PID . Other problems such as perforation, cramping, bleeding, and unwanted pregnancy may be at least indirectly related to IUD surface alterations . It is now agreed that all IUD-associated inflammatory and infectious disease can no longer be considered gonorrheal type PID and that the biodegradation of the nylon-6 tail of the Dalkon shield may also be a factor in PID . Some recommendations are to: 1) change IUDs every 2 years, 2) counsel women on IUD complications and examine IUDs upon removal, and 3) bring IUD technology up to date to develop an IUD that is thoroughly safe and effective .

Appl Environ Microbiol, 1982 Aug, 44(2), 514 - 6
Biodegradation of 2,4,5-trichlorophenoxyacetic acid in soil by a pure culture of Pseudomonas cepacia; Chatterjee DK et al.; A pure culture of Pseudomonas cepacia AC1100 was able to degrade and grow in presence of 2,4,5-trichlorophenoxyacetic acid in soil . At optimum temperature (30 degrees C) and moisture content (15 to 50% {wt/vol}) strain AC1100 could degrade as much as 95% of 2,4,5-trichlorophenoxyacetic acid at high concentration (1 mg/g of soil) within 1 week.

Appl Environ Microbiol, 1982 Aug, 44(2), 321 - 9
Heterotrophic activity and biodegradation of labile and refractory compounds by groundwater and stream microbial populations; Ladd TI et al.; The bacteriology and heterotrophic activity of a stream and of nearby groundwater in Marmot Basin, Alberta, Canada, were studied . Acridine orange direct counts indicated that bacterial populations in the groundwater were greater than in the stream . Bacteria that were isolated from the groundwater were similar to species associated with soils . Utilization of labile dissolved organic material as measured by the heterotrophic potential technique with glutamic acid, phenylalanine, and glycolic acid as substrates was generally greater in the groundwater . In addition, specific activity indices for the populations suggested greater metabolic activity per bacterium in the groundwater . 14C-labeled lignocellulose, preferentially labeled in the lignin fraction by feeding Picea engelmannii {14C}phenylalanine, was mineralized by microorganisms in both the groundwater and the stream, but no more than 4% of the added radioactivity was lost as 14CO2 within 960 h . Up to 20% of {3'-14C}cinnamic acid was mineralized by microorganisms in both environments within 500 h . Both microbial populations appear to influence the levels of labile and recalcitrant dissolved organic material in mountain streams.

Appl Environ Microbiol, 1982 Jul, 44(1), 72 - 8
Biodegradation of 2,4,5-trichlorophenoxyacetic acid by a pure culture of Pseudomonas cepacia; Kilbane JJ et al.; A pure culture of Pseudomonas cepacia, designated AC1100, that can utilize 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as its sole source of carbon and energy was isolated . An actively growing culture of AC1100 was able to degrade more than 97% of 2,4,5-T, present at 1 mg/ml, within 6 days as determined by chloride release, gas chromatographic, and spectrophotometric analyses . The ability of AC1100 to oxidize a variety of chlorophenols and related compounds is also reported.

Appl Environ Microbiol, 1982 Jul, 44(1), 159 - 64
Measurement of aquatic biodegradation rates by determining heterotrophic uptake of radiolabeled pollutants; Pfaender FK et al.; The heterotrophic uptake technique was modified to provide a rapid and simple technique for estimating the rates of biodegradation of organic pollutants under environmental conditions . The methodology is based on an evaluation of uptake into cells and subsequent respiration of radiolabeled organic substrates in short-term experiments . The resulting data can be used to calculate either turnover times or, if multiple concentrations of substrate are used, kinetic parameters . The procedure was applied to assess the biodegradation rates of m-cresol, chlorobenzene, nitrilotriacetic acid, and 1,2,4-trichlorobenzene in fresh, brackish, and marine water samples from the coastal areas of North Carolina . Saturation kinetics for uptake were obtained with each of the compounds tested . Rates of metabolism were shown to be dependent on sample location and time of year.

Appl Environ Microbiol, 1982 Jul, 44(1), 113 - 20
Enhanced biodegradation of methoxychlor in soil under sequential environmental conditions; Fogel S et al.; Ring-U-{14C}methoxychlor {1,1-bis(p-methoxyphenyl)-2,2,2-trichloroethane} was incubated in soil under aerobic and anaerobic conditions . Primary degradation of methoxychlor occurred under anaerobic conditions, but not under aerobic conditions, after 3 months of incubation . Analysis of soil extracts, using gas chromatography, demonstrated that only 10% of the compound remained at initial concentrations of 10 and 100 ppm (wt/wt) of methoxychlor . Evidence is presented that a dechlorination reaction was responsible for primary degradation of methoxychlor . Analysis of soils treated with 100 ppm of methoxychlor in the presence of 2% HgCl2 showed that 100% of the compound remained after 3 months, indicating that degradation in the unpoisoned flasks was biologically mediated . Methanogenic organisms, however, are probably not involved, as strong inhibition of methane production was observed in all soils treated with methoxychlor . During the 3-month incubation period, little or no evaluation of 14CO2 or 14CH4 occurred under either aerobic or anaerobic conditions . Cometabolic processes may be responsible for the extensive molecular changes which occurred with methoxychlor because the rate of its disappearance from soil was observed to level off after exhaustion of soil organic matter . After this incubation period, soils previously incubated under anaerobic conditions were converted to aerobic conditions . The rates of 14CO2 evolution from soils exposed to anaerobic and aerobic sequences of environments ranged from 10- to 70-fold greater than that observed for soils exposed solely to an aerobic environment.

Philos Trans R Soc Lond B Biol Sci, 1982 Jun 11, 297(1088), 481 - 96
Co-metabolism; Dalton H et al.; There have been numerous instances reported when potentially recalcitrant compounds have been modified by microorganisms or completely mineralized by mixed communities or organisms; an example is pesticide biodegradation . Both situations rely upon the ability of microorganisms to transform compounds that they cannot utilize as sole sources of carbon and energy . This phenomenon of co-oxidation or co-metabolism has been fraught with confusion for many years as a result of the ambiguous use of terms and definitions . A redefinition of co-metabolism is proposed in an attempt to alleviate the problem: Co-metabolism--the transformation of a non-growth substrate in the obligate presence of a growth substrate or another transformable compound . The term 'non-growth substrate' describes compounds that are unable to support cell replication as opposed to an increase in biomass . This definition was devised primarily as a result of non-growth substrate metabolism studies with methane-utilizing bacteria . These studies are described in the text . The possible impact of endogenous polymer reserves on co-metabolic events is discussed . A number of examples where non-growth substrate metabolism is of environmental importance are presented, in particular the potential role of methane-oxidizing bacteria in the removal of CO from the environment . The evolutionary significance, if any, of fortuitous metabolism or co-metabolism is discussed, as are potential applications of these phenomena.

J Med Chem, 1982 May, 25(5), 505 - 18
Antitumor agents . 2 . Bisguanylhydrazones of anthracene-9,10-dicarboxaldehydes; Murdock KC et al.; 9,10-Anthracenedicarboxaldehyde bis{(4,5-dihydro-1H-imidazol-2-yl)hydrazone} (bisantrene, VI-1) showed anticancer activity in mice vs . both leukemias and solid tumors . Increases in life span vs . the following neoplasms were: P-388 leukemia, 137%; B-16 melanoma, 122%; Lieberman plasma cell tumor, greater than 85%; colon tumor 26, 150%; Ridgway osteogenic sarcoma, 85% . There were significant numbers of long-term survivors . Both DNA and RNA synthesis were strongly inhibited . The drug was resistant to biodegradation and was bound strongly to tissues; in monkeys the half-life for disappearance from serum was 6 days . Related hydrazones were synthesized, and structure-activity relationships are discussed . Two routes to ring-substituted anthracene-9,10-dicarboxaldehyde intermediates were developed.

Biomaterials, 1982 Apr, 3(2), 81 - 6
The repair of osteochondral defects in osteoarthritic rabbit knees by the use of carbon fibre; Minns RJ et al.; Implants of carbon fibres and carbon fibre patches were tested for their biocompatibility in osteochondral defects in rabbits with instability induced knee osteoarthrosis . The resulting repairs were compared to control holes in which no implant was inserted . There was no apparent biodegradation when fibre bundles were implanted for periods from 2 to 18 weeks, and the carbon fibre patches appeared to induce the gross appearance of a restored joint surface, mechanically strong to loading for periods from 2 to 26 weeks . Also carbon fibre in the form of a patch promoted the healing of the osteochondral defects in osteoarthritic femora with well organised fibrous tissue over repaired subchondral bone . The use of these carbon-fibre patches is suggested as an implant material for the restoration of articular surfaces in osteoarthritis.

J Bacteriol, 1982 Apr, 150(1), 52 - 9
Altered expression of biodegradative threonine dehydratase in Escherichia coli mutants; Merberg D et al.; A number of strains of Escherichia coli K-12 failed to synthesize significant amounts of biodegradative threonine dehydratase (EC 4.2.1.16) when grown anaerobically in tryptone-yeast extract medium, a condition which is optimal for the induction of this enzyme . However, the addition of 10 mM potassium nitrate to the culture medium enabled a few of these strains, notably MB201, to induce the enzyme . An examination of the kinetic parameters, modifier sensitivity, and immunological cross-reactivity revealed that the enzyme produced by MB201 in nitrate-supplemented medium appeared indistinguishable from the dehydratase of a wild-type strain . The reduced expression of threonine dehydratase in MB201 appeared highly specific; the synthesis of two other inducible enzymes, D-serine deaminase and tryptophanase, and two "anaerobic" proteins, namely, fumarate reductase and cytochrome c551, remained unaffected . The mutation (tdcI) responsible for the altered expression of the dehydratase in MB201 was located at min 91 on the E . coli chromosome and appeared to tightly linked to if not identical with pgi, the gene encoding phosphoglucose isomerase, as judged by growth experiments on glucose and fructose, direct assay of phosphoglucose isomerase activity, spontaneous and simultaneous reversion of MB201 (tdcI) to TdcI+ and Pgi+ phenotype, and cosegregation of the two loci during transduction with P1 phage . Because not all strains lacking the dehydratase showed nitrate-dependent enzyme synthesis or had lesions at the pgi locus, it appears that mutations at multiple loci on the E . coli chromosome may influence the expression of the enzyme in vivo.

J Am Acad Dermatol, 1982 Apr, 6(4 Pt 2 Suppl), 643 - 51
Pharmacokinetics of the retinoids isotretinoin and etretinate . A comparative review; Brazzell RK et al.; The clinical pharmacokinetic profiles of two orally administered retinoids, isotretinoin and etretinate, are discussed and compared . The pharmacokinetic profile of isotretinoin is predictable and can be described using linear pharmacokinetic theory . The drug is rapidly absorbed following oral administration, is highly bound to plasma protein, and is metabolized to 4-oxo-isotretinoin . The apparent half-lives of elimination of isotretinoin and 4-oxo-isotretinoin following the oral administration of isotretinoin range from 10 to 20 hours and 24 to 29 hours, respectively . Steady-state pharmacokinetic profiles in patients are consistent with the single-dose pharmacokinetics in normal subjects . Following oral administration, etretinate undergoes significant first-pass biodegradation to its corresponding carboxylic acid; the acid appears rapidly in the circulation, often earlier than the parent drug, and its plasma concentration is usually comparable to, or greater than, that of the parent drug . The apparent elimination rates of drug and metabolite are similar (6-13 hours) following a single dose, suggesting that metabolite elimination may be formation-rate limited . During multiple dosing of etretinate, a very slow terminal elimination phase is observed which is not detected after single-dose administration . The prolonged half-life of this phase suggests accumulation in a deep tissue compartment . Differences between the two retinoids reflect their differing physicochemical properties.

Cancer Res, 1982 Mar, 42(3), 1020 - 5
Advantages in the use of L-asparaginase-albumin polymer as an antitumor agent; Poznansky MJ et al.; Polymeric conjugates of L-asparaginase and an excess of homologous albumin were compared with free L-asparaginase for antitumor activity using a mouse model 6C3HED lymphosarcoma and a human pancreatic tumor cell line, PANC-1 . The asparaginase-albumin polymer is more resistant to proteolytic degradation compared to equivalent amounts of free enzyme and is more effective as an antitumor agent in prolonging survival of C3H/HeJ mice receiving 6C3HED lymphosarcoma . In terms of antitumor activity, the enzyme is approximately 20 times more effective, compared to free enzyme, when given in polymeric form with albumin . Similarly, the polymeric form of L-asparaginase is more effective in inhibiting cell growth of human pancreatic tumor cells grown in tissue culture . The increased effectiveness of the polymeric form of L-asparaginase is probably related to its resistance to biodegradation . The use of cell surface-specific monoclonal antibodies to target the polymer to tumor cells is also demonstrated.

Arch Immunol Ther Exp (Warsz), 1982, 30(5-6), 413 - 20
Prolactin secretion in patients with acute renal failure; Grzeszczak W et al.; In 44 patients with acute renal failure serum prolactin levels were estimated using chloropromazine as a stimulant and alfa-bromocriptine as an inhibitory agent . Significantly elevated basal serum prolactin levels were found both in oliguric and polyuric patients with ARF . Intramuscular (i.m.) administration of chloropromazine markedly increased serum prolactin concentrations . In patients with ARF the apparent half life of prolactin, calculated from the prolactin curve obtained after alfa-bromocriptine administration, was moderately longer than in normals . From the results obtained the following conclusions were drawn: 1 . Hyperprolactinemia of patients with ARF seems to be due predominantly to hypersecretion of this hormone and, to a lesser degree, to impair renal biodegradation . 2 . In patients with ARF prolactin secretion is hyperresponsive to intramuscularly administered chloropromazine.

Arch Environ Contam Toxicol, 1982, 11(1), 33 - 40
Examination of procedures for acute toxicity tests with the fathead minnow and coal synfuel blends; Becker CD et al.; Static and flow-through procedures were examined for conducting acute toxicity tests with the fathead minnow, Pimephales promelas Raf., and water-soluble fractions of a liquid synfuel blend derived from coal . Static conditions were characterized by declines in levels of dissolved oxygen (DO) and total dye-complexable phenolics over the 96-hr test period . Renewal of exposure solutions each 12 or 24 hr retarded, but did not prevent, dissolved oxygen and phenolic declines and periodic disturbance of fish caused stress . Flow-through test conditions, particularly 9.0 volumetric turnovers daily, provided suitably stable levels of DO and phenolics . Mortality reached or exceeded 50% when fish were exposed to about 8.6-8.9 mg l-1 total phenolics during static or renewal tests, but was less than 25% under flow-through conditions . Microorganism development in static solutions was primarily responsible for declines in DO and phenolic levels . Differences in fish mortality between static and flow-through tests suggested the latter was most useful for evaluating toxicity of aqueous extracts from liquified coals . Results of laboratory tests, however, may not accurately portray field conditions where biodegradation or other environmental interactions occur.

Trans Ophthalmol Soc U K, 1982, 102 (Pt 4), 505 - 9
Lens implantation: lessons learned from the first million . The Third Rayner Lecture, 1982; Drews RC; Experience gained from over one million intraocular lens implants has emphasized the importance of quality control, correct design and knowledgeable use of materials . Biodegradation of nylon is well known; polypropylene also degrades, but much more slowly; polymethylmethacrylate does not show evidence of biodegradation even, in one specimen for which I have a control, after 23 years.

Mikrobiologiia, 1982 Jan-Feb, 51(1), 152 - 5
{Effect of cyanobacteria excretions and cell biomass on hydrocarbon-oxidizing mycobacteria}; Gusev MV et al.; The presence of cyanobacterial cells and their exocellular excretions in an aqueous ecosystem stimulated biodegradation of diesel fuel . As was established using the technique of complete factor analysis, nitrogen addition to the medium and the presence of cyanobacterial cells in it are important for the growth of oil-oxidizing bacteria, while exocellular excretions of the cells are not sufficient for such a growth . The mycobacterial growth depended, to a certain extent, on the age of cyanobacterial cultures.

Biomater Med Devices Artif Organs, 1982, 10(3), 205 - 18
Insulin-albumin microbeads: an implantable, biodegradable system; Goosen MF et al.; A feasibility study on developing an implantable, biodegradable insulin delivery system was carried out . Insulin-albumin microbeads (50-1,000 microns diameter) were implanted in diabetic rats . After a single subcutaneous implant of the glutaraldehyde crosslinked microbeads, elevated blood-insulin levels were detected in the diabetic animals for longer than two months . While the blood-insulin levels of the treated animals were sustained between 10 and 67 microU/ml during the initial two month post-implantation period, complete in-vivo biodegradation of the microbeads took longer than five months . The diabetic animals, with the insulin-albumin microbead implants, gained weight . In contrast, untreated diabetic controls lost weight . Fibrous capsules were found to have surrounded the microbeads when the implants were recovered at one and two months post-implantation . The results suggest that the fibrous capsules played a role in retarding insulin release from the albumin microbead system . Cross-linked serum albumin microbeads have the clinical potential of providing long-term in-vivo drug release . This system has the additional advantage of being biodegradable and also provides more options for the method and site of implantation.

Ann Surg, 1982 Jan, 195(1), 55 - 9
A comparison of the effect of pH on the biodegradation of two synthetic absorbable sutures; Chu CC; The differences in hydrolytic degradation of two size 2-0 synthetic absorbable sutures, Polyglycolic acid (Dexon) and Poly(glycolide-lactide) (Vicryl), in the buffer media of three different pH levels ranging from 5.25 to 10.09, were compared in terms of the percentage retention of tensile strength . It was found that Vicryl sutures, in general, exhibited better retention of tensile strength than Dexon sutures within the studied pH range and extent of hydrolysis . When comparing Vicryl with Dexon sutures, the former was only slightly better than Dexon sutures, in the case of an acid environment . The former, however, retained better strength than the latter in a physiological pH (7.44) and under high-alkaline conditions (10.09) . Among the three pH levels tested, Vicryl sutures retained the highest tensile strength in a physiological pH and showed a faster loss of tensile strength in both acidic and high-alkaline conditions . Dexon sutures, however, exhibited better retention of tensile strength in the acidic medium than in an alkaline medium . This pH dependent hydrolysis of Dexon and Vicryl sutures should command surgeons' attention in their selection of synthetic absorbable suture materials for particular needs.

Science, 1981 Dec 4, 214(4525), 1133 - 5
Plasmid-assisted molecular breeding: new technique for enhanced biodegradation of persistent toxic chemicals; Kellogg ST et al.; The persistence of synthetic herbicides such as 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and its release in massive amounts as a herbicide (Agent Orange) have created toxicological problems in many countries . In nature, 2,4,5-T is slowly degraded by cooxidation and is not utilized as a sole source of carbon and energy . The technique of plasmid-assisted molecular breeding has led to the development of bacterial strains capable of totally degrading 2,4,5-T by using it as their sole source of carbon at high concentrations (greater than 1 mg/ml) . Spectrophotometry and gas chromatography reveal various intermediates during growth of the culture with 2,4,5-T.

Biomaterials, 1981 Oct, 2(4), 215 - 20
Aliphatic polyesters II . The degradation of poly (DL-lactide), poly (epsilon-caprolactone), and their copolymers in vivo; Pitt CG et al.; The mechanisms of biodegradation of poly (DL-lactide), poly (epsilon-caprolactone), and copolymers of epsilon-caprolactone with DL-dilactide, delta-valerolactone, and DL-epsilon-decalactone in rabbit were shown to be qualitatively similar . However, the rate of the first stage of the degradation process, non-enzymatic random hydrolytic chain scission, varied by an order of magnitude and was dependent on morphological as well as chemical effects . Weight loss was generally not observed until the molecular weight had decreased to 15,000 or less . Poly (DL-lactide) differed from the other polyesters studied, the rate of chain scission increasing after the commencement of weight loss . The rate of weight loss was greater and the period prior to weight loss was shorter when the comonomer content of copolymers of epsilon-caprolactone was sufficient to reduce the melting point of epsilon-caproate sequences to body temperature.

Anesth Analg, 1981 Sep, 60(9), 666 - 82
Isoflurane: an anesthetic for the eighties?
Wade JG, Stevens WC.
The introduction of isoflurane to clinical practice follows the search for a nonflammable, potent inhalation anesthetic which, above all, is chemically stable so as to resist biodegradation or attack by other chemicals . These attributes characterize isoflurane (Table 2) . The hoped for freedom from hepatic and renal toxicity and from carcinogenic and mutagenic properties is a reality with this drug . Other favorable characteristics include relatively low solubility in blood in relation to anesthetic dose, lack of arrhythmogenic effect, provision of good muscle relaxation, and the absence of central nervous system excitation . Its moderate pungency detracts slightly from the ease of inhaled induction . Disadvantages include respiratory depression, reduced arterial blood pressure, uterine relaxation, decreased uteroplacental blood flow, and likely ability to trigger malignant hyperpyrexia . The frequency and/or significance of tachycardia and dilation of muscle blood vessels in clinical practice remain to be established . We believe isoflurane is a significant improvement over earlier potent inhalation anesthetics.

J Radiol, 1981 Aug-Sep, 62(8-9), 457 - 62
{A study in dogs of micropellets for use in angiographic therapeutic procedures (author's transl)}; Madoule P et al.; A study was conducted in dogs to evaluate the effect on the organism of a new embolisation material: carnauba wax micropellets . The ultimate objective was to study the possible use of micropellets containing an active product for therapy in situ . Renal embolisation was performed by selective or highly selective arterial catheterisation in dogs . Pathological examination demonstrated that only mild foreign body reactions occurred at the embolisation site . Overall tolerance was good . The micropellets were shown to possess some biodegradation properties and to be susceptible to deformation . An attempt is made to define the ideal micropellet from the point of view of size, kinetic features, and biodegradation properties.

J Biomed Mater Res, 1981 Jul, 15(4), 577 - 89
Biodegradation of a poly(alpha-amino acid) hydrogel . I . In vivo; Dickinson HR et al.; A new hydrogel material has been prepared by crosslinking a hydrophilic, nonionic poly(amino acid), poly(2-hydroxyethyl-L-glutamine) . The material properties of the hydrogel can be controlled by variation in the crosslink density, and the swelling ratio was found to be a sensitive and convenient method for measuring the extent of in vivo biodegradation of implanted specimens . Degradation of the material was observed only during the first 2 weeks of subcutaneous implantation in rats, and is attributed to hydrolysis by proteolytic enzymes released during the acute and chronic stages of the normal inflammatory response.

J Biomed Mater Res, 1981 Jul, 15(4), 591 - 603
Biodegradation of a poly-(alpha-amino acid) hydrogel . II . In vitro; Dickinson HR et al.; Proteolytic enzymes have been employed in an in vitro model to simulate the in vivo degradation of a synthetic poly(amino acid) hydrogel . Trypsin and collagenase had no effect on crosslinked poly(2-hydroxyethyl-L-glutamine) but pronase and papain dissolved the hydrogel . The initial effect of papain was to decrease the effective crosslink density without producing soluble material . This effect was similar to that observed previously in vivo . Analysis of the papain digestion products showed that oligomers of degree of polymerization 4-9 were the chief products . The rate at which oligomers were formed increased with increasing crosslink density . This phenomenon was attributed to hydrophobic effects.

Biochem J, 1981 Jun 15, 196(3), 733 - 8
Response of enzymes involved in the metabolism of polyamines to phytohaemagglutinin-induced activation of human lymphocytes; Korpela H et al.; The stimulation of lymphocyte ornithine decarboxylase and adenosylmethionine decarboxylase produced by phytohaemagglutinin was accompanied by an equally marked, but delayed, stimulation of spermidine synthase, which is not commonly considered as an inducible enzyme . In contrast with the marked stimulation of these biosynthetic enzymes, less marked changes were observed in the biodegradative enzymes of polyamines in response to phytohaemagglutinin . Diamine oxidase activity was undetectable during all stages of the transformation . The activity of polyamine oxidase remained either constant or was slightly decreased several days after addition of the mitogen . The activity of polyamine acetylase (employing all the natural polyamines as substrates) distinctly increased both in the cytosolic and crude nuclear preparations of the cells during later stages of mitogen activation . Difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase, although powerfully inhibiting ornithine decarboxylase, produced a gradual enhancement of adenosylmethionine decarboxylase activity during lymphocyte activation, without influencing the activities of the two propylamine transferases (spermidine synthase and spermine synthase).

Science, 1981 Jan 9, 211(4478), 132 - 8
Biodegradation of chemicals of environmental concern; Alexander M; Microorganisms in soils and waters convert many synthetic organic chemicals to inorganic products . Other compounds are transformed only by cometabolism . These microbial processes may lead to environmental detoxication, the formation of new toxicants, or the biosynthesis of persistent products . Type reactions are proposed for major categories of enzymatic transformation of synthetic chemicals in soils, natural waters, and sewage . Some organic molecules are resistant to microbial attack, and explanations for the persistence of such compounds are suggested.

Polim Med, 1981, 11(2), 117 - 31
{Polymer fibers in surgery . I.}; Privalova LG et al.; The contemporary application of the numerous classes of polymer fibres fibres such as collagenous, polyethereal, polyolefinic, polyamidic etc . for the practical surgery is reviewed, as well as the superiority of synthetic fibres to natural ones is discussed . The basic criteria of application of those materials to surgery, as well as the possible modifications of polymers are described . The areas of medical complications of the numerous types of polymer fibres as well as its behaviour in the organisms are observed . The mechanism of biodegradation of polymers implanted into the organism is discussed . The method of prognosis of lifetime of implanted polymer articles is described.

Int J Pept Protein Res, 1981 Jan, 17(1), 72 - 88
Topochemically related hormone structures . Synthesis of partial retro-inverso analogs of LH-RH; Chaturvedi N et al.; The syntheses of five partial retro-inverso luteinizing hormone-releasing hormone (LH-RH) analogs {g-Tyr5, m-Gly6}LH-RH, {g-Tyr5-r-Gly6, R,S-m-Leu7} LH-RH, {g-p-Glu1, m-His2}LH-RH, {g-p-Glu1-r-D-His-R,S-m-Trp3}LH-RH, and {g-Pro9-propionyl-des-Gly10}LH-RH, have been accomplished by solution methods . The choice of sequence to be reversed was based on suggested biodegradation mechanisms of LH-RH . A (gem)-diamino alkylidene residue, which was produced via Curtius rearrangement of a peptide segment, and a 2-substituted malonyl residue mark the initiating and terminating site, respectively, of the reversed sequence.

J Environ Sci Health B, 1981, 16(1), 35 - 47
Biotransformation of the pesticide sodium arsenate; Shariatpanahi M et al.; Biotransformation is an important parameter in assessing the environmental impact and fate of pesticides since metabolites produced may be either more or less toxic than the parent compound . Sodium arsenate (+5 inorganic), the wood preservative and insecticide, may be converted to both inorganic (+3) and organic compounds (-3) by microorganisms in soil, sediment and water bodies . Biotransformation of sodium arsenate was studied in pure cultures of 5 bacterial species using a mineral salt and limited carbon source medium . Arsenate concentrations were 10 microgram/ml and 100 microgram/ml of arsenic respectively . The rate of biodegradation of the parent compound was described by a first order composite exponential equation of the form Ct = C1e-k1t+C2e-k2t . Rates of production of metabolites (arsenite, monomethylarsine, dimethylarsine and trimethylarsine) were described by a first order exponential equation of the form Ct = Co (1-e-kt).

NIDA Res Monogr, 1981, 28, 187 - 93
A review of parenteral sustained-release naltrexone systems; Olsen JL et al.; The ideal naltrexone sustained-release delivery system should be easy to inject or implant, not cause adverse tissue reaction, release the drug at a relatively constant rate for at least 30 days, and biodegrade within a short time afterwards . Mechanisms which can be used for sustaining drug release include reducing solubility and surface area, coating, encapsulation and microencapsulation, complexation, binding and hydrophilic gelation . Drug release from such systems is controlled by diffusion through a barrier/film, diffusion from a monolithic device, erosion of the surface, hydrolysis, ion exchange, biodegradation, or a combination of these . Injectable systems would seem to be ultimately preferred because of the ease of administration and handling, while the implantable devices may find first use in man since they are easily removable, should that be necessary . Maintaining particulate-free products and sterilization methods are two problems with all parenteral dosage forms . Production must be particularly well controlled and validated.

J Clin Invest, 1980 Dec, 66(6), 1258 - 64
Regulation of glycolytic enzyme activity during chronic hypoxia by changes in rate-limiting enzyme content . Use of monoclonal antibodies to quantitate changes in pyruvate kinase content; Hance AJ et al.; Monoclonal antibodies were prepared against pyruvate kinase (PyKi; ATP: pyruvate phosphotransferase, EC 2.7.1.40) and used to quantitate PyKi content in L2 lung cells and WI-38 fibroblasts cultivated under hypoxic and normoxic conditions . After 96 h of hypoxic cultivation, PyKi activity was significantly increased in both cell types (L2: normoxia {Po2 = 142 torr}, 0.11 +/- 0.01 {SD}; hypoxia {Po2 = 14 torr}, 0.25 +/- 0.04 U/microgram DNA, P < 0.01) . PyKi content increased proportionately in both cell lines (L2: normoxia, 0.44 +/- 0.13; hypoxia, 0.94 +/- 0.13 microgram enzyme protein/microgram DNA) . Specific activity was not significantly different after 96 h (L2: normoxia, 261 +/- 11; hypoxia, 261 +/- 14 U/mg enzyme protein) . These results indicate that regulation of glycolysis during chronic hypoxia occurs at the level of enzyme content . Chronic O2 depletion leads to either an increased rate of biosynthesis or a decreased rate of biodegradation of PyKi, causing augmented glycolytic capacity . Monoclonal antibodies provide a highly specific, convenient approach to charcterizing enzymes, as well as quantitating cellular enzyme content.

J Biomed Mater Res, 1980 Nov, 14(6), 753 - 64
Biological effects of residual glutaraldehyde in glutaraldehyde-tanned collagen biomaterials; Speer DP et al.; Glutaraldehyde is commonly used to control physical and biological properties of collagen structure by means of intramolecular and/or intermolecular crosslinking of collagen molecules . Solubility, antigenicity, and biodegradation of naturally occurring or reconstituted collagenous matrices are effectively reduced by glutaraldehyde treatment . Adverse biological reactions to glutaraldehyde have been limited to infrequent contact dermatitis and to biocidal effects which are exploited in chemical sterilization media . In the present study of glutaraldehyde-tanned collagen sponge, the presence of glutaraldehyde was correlated with cytotoxic effects upon fibroblasts in tissue culture and foreign body giant cell reaction to bioimplants of the sponge . Fibroblast growth in tissue culture is 99% inhibited at media concentrations of 3.0 ppm glutaraldehyde . Extracts of glutaraldehyde collagen sponge in aqueous media at pH 7 and 4.5 yielded 6 micrograms and 65 micrograms glutaraldehyde per gram of collagen sponge, respectively . The yield increased tenfold at pH 4.5 . Observations indicate that leaching of the glutaraldehyde from glutaraldehyde-tanned collagen sponge is sufficient to produce potentially adverse cellular effects both in vivo and in vitro.

G Batteriol Virol Immunol, 1980 Jul-Dec, 73(7-12), 242 - 52
{Effect of biological activation on the evolution of microflora during composting of urban waste}; Ozino Marletto OI et al.; In two solid urban wastes piles, one treated with 7.5% of good bovine manure, the other used as a test, the evolution of the microflora has been studied, during the first period of biodegradation and at the end of the maturation process, in order to control if bioactivation can positively affect the biodegradation development . Actinomytcetes and fungi have been examined, and the following functional microbial groups: aerobic nitrogen fixing bacteria, ammonia bacteria, proteolytics, nitrosants, nitricants, aerobic cellulolytics, amilolytics, pectinolytics . During the process, no significant quantitative difference between the microflora of the two piles was found, except for aerobic cellulolytic, which were strongly superior in number in the end product from the bioactivated pile.

J Oral Surg, 1980 Apr, 38(4), 251 - 6
A composite of porous calcium sulphate dihydrate and cyanoacrylate as a substitute for autogenous bone; Frame JW; Implants of porous calcium sulphate dihydrate with a surface coating of n-butyl 2-cyanoacrylate were studied in circular defects in the skulls of rabbits to determine the extent of their replacement by new bone and to examine the reaction of the surrounding tissue . The defects were compared with control cavities that were allowed to fill with blood clot . The material was well tolerated by the tissues and did not slow bony healing . The pattern of ingrowth of bone in the skulls with implants was different than that of the controls . Further investigations are being undertaken to strengthen the implants and to adjust the rate of biodegradation . Possible future clinical applications are discussed.

Polim Med, 1980, 10(1), 19 - 29
{Chemical composition of linear polyurethanes and the rate of their destruction in physiological solution and animal body}; Lipatova TE et al.; The examinations of biodestruction of segmental polyurethanes from hexamethylene diisocyanate ethylene glycol and polyesters with different chemical composition: polydiethylene glycol succinate, molecular mass 750 (formula A-19), polydiethylene glycol adypates, molecular mass 800 and 1500 (formula A-14 and A-10) were performed employing physico-chemical and histological methods . It was noted that in physiological liquids and animal organisms that polyurethanes containing more polyester bounds, which easily undergo hydrolytic decomposition, had decomposed in higher rate - A-10 > A-19 > A-14 . Histological examination revealed the hydrolytic destruction of samples A-19 and A-10 during 24 weeks . However, the rate and biodestruction degree in sample A-10 (especially in ensuring period) was found to be higher than in sample A-19 . This appears in its fragmentation and cell activation in connective tissue, surrounding the alloplastic material . These data are consistent to the results of physico-chemical examinations which revealed that sample A-10 after 24 weeks completely loose the durability and the molecular mass diminishes almost four times, while the sample A-19 maintains 37% of durability comparing to initial condition and molecular mass diminishes only two times . Sample A-14 undergoes destruction, at lower degree maintains 50% of durability and its molecular mass diminishes almost two times . The performed examinations show that the changes of ester groups concentration in polyurethanes give the possibility of regulation of the biodegradation rate.

Ophthalmologica, 1980, 180(4), 228 - 33
Histopathological changes after pseudophakos; Sutton GA et al.; Cataract extraction and iris clip lens implantation in an 88-year-old woman were followed by hyphaema, anterior uveitis and organised exudates around the implant . The globe was enucleated after 15 months due to pain and a poor visual prognosis . Sections showed an epithelial downgrowth into part of the anterior chamber, associated with a fibrous membrane which had surrounded part of one loop of the implant . Atrophy of the iris, adenomatous changes in a ciliary process and an after-cataractous ring were noted . Inflammatory changes were present in the uvea, associated posteriorly with degenerative choroido-retinitis, probably of arteriosclerotic origin . The nylon loops of the implant showed areas of biodegradation and were partly fibrosed in . The possible relationship of the various changes is discussed.

Arch Environ Contam Toxicol, 1980, 9(3), 289 - 305
Studies on the degradation of atrazine by bacterial communities enriched from various biotopes; Geller A; Degradation of 14C-ring labeled atrazine (2-choloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) by bacterial populations from soil, waters and activated sludges was investigated and compared with non-biological decomposition in sterile solutions . Within two weeks, 0.6% Cl-deethyl- and 0.1% Cl-deisopropylatrazine had been formed in sterile 0.02 M phosphate buffer, pH 7.2 . In biodegradation studies, bacterial populations were enriched and incubated in media containing atrazine and high or low levels of nutrients . Nutrient supply had a strong effect on the fate of atrazine in bacterial cultures, whereas the origin of bacteria was of minor importance . In 31 of 33 mixed populations investigated, the herbicide was largely converted to unidentified compounds . Incubation with high levels of nutrients resulted in 17% to 57% of these compounds being constant after one and two weeks of incubation . In parallel experiments with low nutrient supply, the compounds were present in amounts of 7% to 57% after one week . The proportions of the unidentified compounds dropped within the second week of incubation, while atrazine reappeared correspondingly . The amounts of dealkylated metabolites generally did not exceed those of sterile solutions . The results indicate that atrazine is not degraded by bacteria but bound, thus simulating biodegradation . Evidence is presented that physicochemical decomposition of the herbicide is more significant than microbial degradation.

Antonie Van Leeuwenhoek, 1980, 46(1), 27 - 39
Extraction, distribution and biodegradation of bacterial lipopolysaccharides in estuarine sediments; Saddler JN et al.; Lipopolysaccharides (LPS), added as whole bacteria to estuarine sediments, were extracted efficiently by both trichloroacetic acid (TCA) and phenol--water (PW) . Amounts of recovered LPS were measured indirectly by analyses for ketodeoxyoctonate (KDO), beta-hydroxymyristic acid, immunodominant sugars and anticomplementary (AC) activity towards human complement . TCA was judged to be better than PW for routine extraction of sediments because, although it yielded 10--20% less LPS, it avoided contamination with non-LPS, high-molecular weight material with high AC activity . In sediment samples taken as cores from estuarine beaches, the concentration of endogenous LPS diminished rapidly with depth below the topmost 1 cm . KDO disappeared more rapidly with depth than AC activity . When known LPS was incubated with estuarine beach mud at 20--22 degrees C for 3 weeks there was extensive biodegradation of both the lipid and polysaccharide components, the latter more rapidly . LPS-degrading bacteria were isolated.

J Environ Sci Health B, 1980, 15(4), 421 - 9
Persistence and biodegradation of carbaryl in soils; Venkateswarlu K et al.; The persistence of the methylcarbamate pesticide carbaryl was studied in four soils under flooded conditions . A substantial portion of the pesticide was recovered from all soils even after 15 days of its application, with the recovery ranging from 37% in an alluvial soil to 73% in an acid sulfate soil . The degradation of carbaryl was more rapid under flooded conditions than under nonflooded conditions . A bacterium, Pseudomonas cepacia, isolated from a flooded soil amended with a related methylcarbamate pesticide carbofuran, degraded carbaryl in a mineral medium supplemented with yeast extract.

J Neurosci Res, 1980, 5(1), 73 - 8
The fate of tritium-labeled reserpine in the chick embryo: a preliminary report; Dahl AL et al.; After a single administration of EH-reserpine, 10 mugm 2.5 microCi, into the yolk of fertilized chicken eggs, gross radioactivity (reserpine plus degradation products) and the unchanged labeled drug, separated by thin layer chromatography, were assayed on the 8th and 19th day of incubation . Nanogram per gram concentrations of unchanged 3H-reserpine were recovered at both times . The 3H-reserpine recovered in the whole egg on the 8th day of incubation accounted for up to 20% of the administered dose . On the 19th day of incubation, brain showed the largest share (28%) of 3H-reserpine as a percentage of gross radioactivity of all organs investigated . Reserpine underwent considerable biodegradation in the developing chick embryo, but the concentrations of unchanged drug recovered in embryonal tissues throughout development were of the same order as those persisting in target organs of rats given a pharmacological dose of reserpine.

Am J Ophthalmol . 1979 Dec;88(6):982-9?
Broken nylon iris fixation sutures; Cohan BE et al.; Broken nylon iris sutures, used to fixate the Worst suture lens, occurred in 41 of a series of 215 eyes, a remarkably high frequency . The estimated average time to break was 27.8 months . Over three fourths of the borken sutures were discovered incidentally on a return visit . Complications related to the broken suture occurred in 21 eyes . The characteristic complication was corneal epithelial edema caused by intermittent touch of the endothelium by the broken suture; spontaneous lens dislocation was infrequent . Light and scanning electron microscopy revealed that biodegradation caused the suture break . Broken iris sutures can be avoided by fixation of the lens with a nonbiodegradable suture.

Appl Environ Microbiol, 1979 Oct, 38(4), 742 - 6
Microbial growth on hydrocarbons: terminal branching inhibits biodegradation; Schaeffer TL et al.; A variety of octane-utilizing bacteria and fungi were screened for growth on some terminally branched dimethyloctane derivatives to explore the effects of iso- and anteiso-termini on the biodegradability of such hydrocarbons . Of 27 microbial strains tested, only 9 were found to use any of the branched hydrocarbons tested as a sole carbon source, and then only those hydrocarbons containing at least one iso-terminus were susceptible to degradation . Anteiso-or isopropenyl termini prevented biodegradation . None of the hydrocarbonoclastic yeasts tested was able to utilize branched-hydrocarbon growth sustrates . In the case of pseudomonads containing the OCT plasmid, whole-cell oxidation of n-octane was poorly induced by terminally branched dimethyloctanes . In the presence of a gratuitous inducer of the octane-oxidizing enzymes, the iso-branched 2,7-dimethyloctane was slowly oxidized by whole cells, whereas the anteiso-branched 3,6-dimethyloctane was not oxidized at all . This microbial sampling dramatically illustrated the deleterious effect of alkyl branching, especially anteiso-terminal branching, on the biodegradation of hydrocarbons.

Appl Environ Microbiol, 1979 Oct, 38(4), 715 - 22
Enzyme recruitment allows the biodegradation of recalcitrant branched hydrocarbons by Pseudomonas citronellolis; Fall RR et al.; Experiments were carried out to construct pseudomonad strains capable of the biodegradation of certain recalcitrant branched hydrocarbons via a combination of alkane and citronellol degradative pathways . To promote the metabolism of the recalcitrant hydrocarbon 2,6-dimethyl-2-octene we transferred the OCT plasmid to Pseudomonas citronellolis, a pseudomonad containing the citronellol pathway . This extended the n-alkane substrate range of the organism, but did not permit utilization of the branched hydrocarbon even in the presence of a gratuitous inducer of the OCT plasmid . In a separate approach n-decane-utilizing (Dec+) mutants of P . citronellolis were selected and found to be constitutive for the expression of medium- to long-chain alkane oxidation . The Dec+ mutants were capable of degradation of 2,6-dimethyl-2-octene via the citronellol pathway as shown by (i) conversion of the hydrocarbon to citronellol, determined by gas-liquid chromatography-mass spectrometry, (ii) induction of geranyl-coenzyme A carboxylase, a key enzyme of the citronellol pathway, and (iii) demonstration of beta-decarboxymethylation of the hydrocarbon by whole cells . The Dec+ mutants had also acquired the capacity to metabolize other recalcitrant branched hydrocarbons such as 3,6-dimethyloctane and 2,6-dimethyldecane . These studies demonstrate how enzyme recruitment can provide a pathway for the biodegradation of otherwise recalcitrant branched hydrocarbons.

Appl Environ Microbiol, 1979 Sep, 38(3), 551 - 3
Biodegradation of polystyrene, poly(metnyl methacrylate), and phenol formaldehyde; Kaplan DL et al.; The biodegradation of three synthetic 14C-labeled polymers, poly(methyl methacrylate), phenol formaldehyde, and polystyrene, was studied with 17 species of fungi in axenic cultures, five groups of soil invertebrates, and a variety of mixed microbial communities including sludges, soils, manures, garbages, and decaying plastics . Extremely low decomposition rates were found . The addition of cellulose and mineral failed to increase decomposition rates significantly.

Sci Total Environ, 1979 Sep, 13(1), 71 - 86
Determination of polycyclic aromatic hydrocarbons in sediments and mussels from Saudafjord, W . Norway, by glass capillary gas chromatography; Bjorseth A et al.; Polycyclic aromatic hydrocarbons (PAH) have been determined, by glass capillary gas chromatography, in two species of bivalves (Mytilus edulis and Modiolus modiolus) and sediments of Saudafjorden, Norway . The PAH observed are derived from waste effluents from a ferro alloy smelter . Up to 34 PAH compounds were identified, including some reported to be carcinogenic . The concentrations decreased rapidly with distance from the source and with sediment depth, but could be traced more than 15 km from the source . Relative abundance of various PAH did not change significantly in the mussels collected from the head to the mouth of the fjord . In the sediments, however, phenanthrene increased from minor importance to dominance towards the mouth, whereas the relative content of anthracene and benzo {a}pyrene decreased . The results are compared with observations from other marine localities and discussed in relation to transport processes, biodegradation and chemical transformation in the sediments.

J Biol Chem, 1979 Aug 25, 254(16), 7927 - 34
The role of glyoxylate in the regulation of biodegradative threonine dehydratase of Escherichia coli; Park LS et al.; The activity of biodegradative threonine dehydratase of Escherichia coli K12 was reversibly inhibited by glyoxylate in the presence of AMP . Kinetic analysis showed that the inhibition was mixed with respect to L-threonine and competitive in terms of AMP; the inhibitory effect of glyoxylate was less pronounced at high protein concentrations . Incubation of dehydratase with L-threonine shifted the absorption maximum of the enzyme-bound pyridoxal phosphate from 413 to 425 nm; addition of glyoxylate completely prevented the threonine-mediated spectral shift . In addition to the inhibitory effect, incubation of purified enzyme with glyoxylate resulted in a progressive, irreversible inactivation of the enzyme and formation of inactive protein aggregates . The rates of inactivation were decreased with increasing concentrations of protein and AMP . During inactivation by glyoxylate, the 413-nm absorption maximum of the native enzyme was replaced by a new peak at 385 nm . Experiments with {14C}glyoxylate showed a rapid binding of 1 mol of glyoxylate per 147,000 g followed by a slow binding of 3 additional mol of glyoxylate; the glyoxylate-protein linkage was stable to acid precipitation and protein denaturants . Competition binding experiments revealed that pyruvate (which also inactivated the E . coli enzyme, Feldman, D.A., and Datta, P . (1975) Biochemistry 14, 1760-1767) did not interfere with the binding of glyoxylate or vice versa, suggesting that the two keto acids may occupy separate sites on the enzyme molecule . Nevertheless, experiments on enzyme inactivation using glyoxylate plus pyruvate reveal mutual interactions between these ligands in terms of lack of additive effect, retardation in the spectral shift due to glyoxylate, and stabilization of the enzyme in the presence and absence of AMP . We conclude from these results that the control of biodegradative threonine dehydratase is governed by a complex set of regulatory events resulting from reversible and irreversible association of these effectors with the enzyme molecule.

Fertil Steril, 1979 May, 31(5), 545 - 51
A new long-acting injectable microcapsule system for the administration of progesterone; Beck LR et al.; PIP: A longacting injectable microcapsule system for the controlled-release systemic administration of progesterone is described and photographed . The microcapsules are made of biodegradable polymer which contain crystalline progesterone . After injection, the progesterone is released over time from the microcapsules by diffusion and biodegradation of the polymer matrix . Rats and baboons were used to evaluate the in vivo rates of progesterone release from different capsule preparations . Results are graphed and tabulated . Tests showed that 50% of the progesterone is available for quick release while the other 50% remains to be released at a slower rate . Smaller microcapsules released the progesterone at a greater rate and a shorter duration . By using larger microcapules, it should be possible to extend the useful duration of the microcapsule system . Vaginal estrus cycles in rats and cyclic ovarian function in baboons were inhibited for 1 month following injection of the progesterone microcapsules . This method of delivery has the advantages that it obviates cyclic overdosing and underdosing and it can be delivered both locally and systemically .

Plast Reconstr Surg, 1979 May, 63(5), 626 - 33
Bone regeneration within a coralline hydroxyapatite implant; Holmes RE; The hypothesis that incomplete resorption of osteons in an autogenous cortical bone graft may limit its replacement by new bone regeneration was explored by implanting a hydroxyapatite replica of a coral skeletal structure into bone gaps . This implant contained channels and interconnections similar to those in osteon-evacuated bone grafts . In 6 implanted mandibular defects in dogs, two of which were examined at two, 4, and 6 months, 11 percent, 46 percent, and 88 percent of the implant areas were filled with regenerated bone . The regenerated bone was a woven type at two months, but changed to a lamellar type by 6 months . In two implanted defects examined at 12 months, biodegradation of 29 percent of the implant had occurred . The bone regeneration was physiological, the implant was biocompatible, and the biodegradation began after the bone had regenerated.

Trans Ophthalmol Soc U K, 1979 Apr, 99(1), 183 - 6
Biodegradation of nylon loops of intraocular implants in children; Mehta HK; In none of the 418 first-stage intraocular implant insertions with intracapsular cataract extractions I have carried out in adults is there any clinical evidence of nylon loop degradation . Although there are no previous reports of clinically observable implant loop degradation, clinically detectable biodegradation was found in eleven eyes of seven children and four adults among the 34 second-stage iris-clip or iridocapsular implants I inserted after aspiration of cataract in children and young adults . The degradation has not produced any uveitis, keratopathy, or instability of the implants in any of these patients . Two children had unilateral glaucoma in the eye containing an iris-clip implant . One of them had dense amblyopia in that eye and the iris-clip implant was removed at the time of trabeculectomy . Scanning electron microscopy of this implant is reported . Active search for nylon particles in the trabeculectomy specimen of the second child has shown the presence of strongly birefringent particles in the trabecular tissue . The possible mechanism of biodegradation of the nylon loops is discussed.

Appl Environ Microbiol, 1979 Apr, 37(4), 729 - 39
Effect of environmental parameters on the biodegradation of oil sludge; Dibble JT et al.; A laboratory study was conducted with the aim of evaluating and optimizing the environmental parameters of "landfarming", i.e., the disposal by biodegradation in soil of oily sludges generated in the refining of crude oil and related operations . Oil sludge biodegradation was monitored by CO2 evolution and by periodic analysis of residual hydrocarbons . The parameters studied were soil moisture, pH, mineral nutrients, micronutrients, organic supplements, treatment rate, teratment frequency, and incubation temperature . Oil sludge biodegradation was optimal at a soil water-holding capacity of 30 to 90%, a pH of 7.5 to 7.8, C:N and C:P ratios of 60:1 and 800:1, respectively, and a temperature of 20 degrees C or above . Addition of micronutrients and organic supplements was not beneficial; sewage sludge interfered with hydrocarbon biodegradation . Breakdown of the saturated hydrocarbon (alkane and cycloalkane) fraction was the highest at low application rates, but higher application rates favored the biodegradation of the aromatic and asphaltic fractions . An application rate of 5% (wt/wt) oil sludge hydrocarbon to the soil (100,000 liters/hectare) achieved a good compromise between high biodegradation rates and efficient land use and resulted in the best overall biodegradation rate of all hydrocarbon classes . Frequent small applications resulted in higher biodegradation than single large applications . Two 100,000-liter/hectare (255 barrels per acre) or four 50,000-liter/hectare oil sludge hydrocarbon applications per growing season seem appropriate for most temperate zone disposal sites.

Appl Environ Microbiol, 1979 Mar, 37(3), 619 - 25
Utilization of chlorobenzoates by microbial populations in sewage; DiGeronimo MJ et al.; Microorganisms in sewage decomposed 3.4-dichlorobenzoate and m-, p-, and o-chlorobenzoates . As the substrate disappeared, populations capable of growing on these compounds proliferated . Neither 2,4-dichlorobenzoate nor 2,3,6-trichlorobenzoate was destroyed by the sewage microflora . The addition of glucose or benzoate and m-chlorobenzoate to the sewage did not promote degradation of 2,4-di- or 2,3,6-trichlorobenzoates . The populations responsible for the biodegradation of the chlorinated compounds were initially less than 100 cells/ml . During the metabolism of m-chlorobenzoate, 5-chlorosalicylate and 4-chlorocatechol were formed.

Naturwissenschaften, 1979 Jan, 66(1), 22 - 7
{Chemical mechanism of the effect of alcohol}; Bringmann G; The formation of tetrahydro-isoquinoline alkaloids in human and animal metabolisms subsequent to alcohol consumption is reported . The spectrum of identified products ranges from simple structures such as salsolinol to the complicated skeleton of protoberberines . These substances, hitherto found exclusively in plants, interfere with the biosynthesis, biodegradation and neurotransmission of the structurally closely related biogenic amines from which they are formed, and thus affect the vegetative nervous system.

Eur J Biochem, 1978 Nov 15, 91(2), 527 - 32
Biodegradative threonine dehydratase . Reduction of ferricyanide by an intermediate of the enzyme-catalyzed reaction; Datta P et al.; The threonine-dependent reduction of ferricyanide catalyzed by the purified biodegradative threonine dehydratase of Escherichia coli has been studied . The rate of production of 2-oxobutyrate in the presence of ferricyanide was lower than that found in the absence of ferricyanide . The concentrations of threonine required for half-maximal effects for the reduction of ferricyanide and, in the presence of the dye, for 2-oxobutyrate production, were 3 mM and 9mM, respectively . Reduction of ferricyanide was accompanied by evolution of CO2, and even within a very short incubation time with the enzyme, the ratio of ferricyanide reduced over CO2 evolved was approximately 7 . Stopping the enzyme activity after a brief exposure to threonine at pH 9.7 resulted in the accumulation of an intermediate (with a half-life of 4 min at 25 degrees C) which formed an adduct with N-ethylmaleimide; the accumulated intermediate, in the absence of N-ethylmaleimide, reduced ferricyanide with concomitant evolution of CO2 . We conclude from these results that 2-aminocrotonate is the intermediate which serves as a source of reducing equivalent for ferricyanide, and nonstoichiometric amount of ferricyanide reduction may be attributed to some secondary reactions of ferricyanide with compounds derived from the oxidation product of 2-aminocrotonate.

Ann N Y Acad Sci, 1978 Sep 29, 298, 104 - 10
Effects of microbial activity on aquatic pollutants; Voll MJ et al.; Bacteria and fungi present in estuarine and marine water and sediment accomplish significant degradation of crude oil, refined oils, polychlorinated biphenyls, and organomercurials, with the rate and extent of degradation varying with species, geographic source, temperature, and other biologic and environmental parameters . Our biodegradation studies have been extended to determine if physical weathering and/or microbial degradation of oil by microorganisms present in Chesapeake Bay water and sediment produces potentially carcinogenic substances . Water and sediment from an area in Chesapeake Bay that receives heavy input of oil and from a relatively nonpolluted site have been assayed for mutagenic ability by use of the Ames method, which is a bacterial assay and is highly sensitive . Preliminary findings indicate the presence of mutagenic substances in samples collected from the polluted site . Extracts of oil subjected to microbial degradation under controlled laboratory conditions did not yield detectable mutagenic activity . In situ studies are in progress.

J Bacteriol, 1978 Sep, 135(3), 828 - 40
Control of biodegradative threonine dehydratase inducibility by cyclic AMP in energy-restricted Escherichia coli; Phillips AT et al.; To explain the requirement for anaerobic conditions in the induction of biodegradative L-threonine dehydratase in Escherichia coli, Crookes strain, measurements of cyclic AMP (cAMP) were made during aerobic and anaerobic growth and upon an aerobic-to-anaerobic transition . Internal cAMP levels were similar (5 to 10 muM) throughout exponential growth, whether aerobic or anaerobic, but only during anaerobiosis was threonine dehydratase synthesized . When an exponentially growing aerobic culture was made anaerobic, a sharp increase in internal cAMP was noted, reaching 300 muM within 10 min and declining thereafter to normal anaerobic levels . Threonine dehydratase synthesis was detected immediately after the attainment of peak cAMP levels and continued for several generations . A similar pattern but with less accumulation of cAMP and less threonine dehydratase production was also noted upon treatment of an aerobically growing culture with KCN . Pyruvate addition at the time of anaerobic shock severely affected both cAMP accumulation and threonine dehydratase synthesis; however, externally added cAMP could partially counter the pyruvate effect on enzyme synthesis . The conclusion was reached that conditions which resulted in a temporary energy deficit brought about the major accumulation of cAMP, and this elevated level served as a signal for initiation of threonine dehydratase synthesis to supply energy by the nonoxidative degradation of threonine.

Mycopathologia, 1978 Aug 10, 63(3), 145 - 53
Aflatoxin is degraded by mycelia from toxigenic and nontoxigenic strains of aspergilli grown on different substrates; Doyle MP et al.; The ability of 9-day-old mycelia of Aspergillus parasiticus NRRL 2999 to degrade aflatoxin varied depending on the substrate used to grow the mold . Substrates which allowed substantial mycelial growth yielded mycelia which actively degraded aflatoxin . Substrates which allowed minimal growth of mycelia yielded mycelia with little ability to degrade aflatoxin . Biodegradation of aflatoxin was also strain-dependent . A . parasiticus NRRL 2999 and NRRL 3000 actively degraded aflatoxin, A . flavus NRRL 3353 was less active, and A . flavus NRRL 482 and A . parasiticus NRRL 3315 degraded minimal amounts of aflatoxins . Those aspergilli producing greatest amounts of aflatoxin also degraded aflatoxins most rapidly, whereas those strains which produced minimal amounts of aflatoxin generally degraded aflatoxins less effectively . Substrates which allowed maximum aflatoxin production also yielded mycelia which actively degraded aflatoxins, whereas media which allowed limited production of aflatoxin generally yielded mycelia with minimal ability to degrade the toxin . Although exceptions exist, generally as aflatoxin production increased so did the ability of mycelia to degrade the toxin.

J Bacteriol, 1978 Aug, 135(2), 324 - 33
Biodegradation of acyclic isoprenoids by Pseudomonas species; Cantwell SG et al.; The ability of various pseudomonads to utilize acyclic isoprenoids as a sole carbon source was investigated . Tests for utilization of acyclic isoprenols such as citronellol and geraniol were complicated by toxic effects of these alcohols, and most species tested were killed by exposure to citronellol or geraniol (0.1%, vol/vol) in liquid culture . In the case of Pseudomonas citronellolis, sensitivity to isoprenols is reduced by prior induction of the isoprenoid degradative pathway via either growth on succinate in the presence of citronellol or growth on citronellic acid . For this species, citronellic acid proved to be the best isoprenoid growth substrate tested . Geraniol utilization as a taxonomic indicator for different subgroups of pseudomonads is discussed . Only a few of the species tested were able to utilize acyclic isoprenoids . Two species which utilize C10 acyclic isoprenoids, P . aeruginosa and P . mendocina, were shown to contain the inducible enzyme geranyl-coenzyme A carboxylase, one of the unique enzymes in the isoprenol degradative pathway known to occur in P . citronellolis . Of the species which utilized geranitol, none showed definite growth on the homologous C15 and C20 isoprenols.

Can J Microbiol, 1978 Jun, 24(6), 725 - 33
{Ultrastructural study of the biodegradation processes . I . Beech (Fagus sylvaticus L.) leaf white rot}; Reisinger O et al.; An electron microscopic study of beech leaf white rot shows a certain number of characteristic developmental stages which are identical whether the material is from in vitro experimentation or from natural incubation . Endowed with a cellulolytic properly seemingly localized in the apical region only, hyphae of the white rot agent only traverse the plant cell walls . Subsequently, hyphae penetrate condensed protoplasmic residues and make them progressively transparent to electrons . During this discoloring process, a lethal factor of as yet unknown nature appears, affecting other microorganisms already present in the leaves . Phloem and xylem vascular bundles do not present notable ultrastructural modifications . Therefore, leaf discoloration is not due to an alteration of the xylem constituents but to changes having occurred in the condensed cytoplasmic residues of the dead tissues.

Probl Endokrinol (Mosk), 1978 May-Jun, 24(3), 74 - 9
{Relationship between prolactin and serum proteins . 1 . Protein-bound hormone protected from biodegradation in the kidneys}; Marinchenko GV et al.; The authors studied binding of prolactin labeled with 125I in the blood of rats and lactating goats . Not over 20% of the hormone was bound in vitro the first 5 to 10 min of incubation with the blood serum, and a complex with molecular weight of 200 000 appeared which was similar to that formed in vivo . With a longer incubation 125I-prolactin was bound in serum macroglobulin fraction; this was not observed in vivo . Blood protein-bound prolactin retained its immunological activity . Monomeric hormone was absorbed in the kidneys and the mammary glands, with the subsequent rapid degrading . Blood protein-bound prolactin was not absorbed in the kidneys, and was present in the mammary glands in small amounts only.

Appl Environ Microbiol, 1978 May, 35(5), 890 - 6
Kinetics of biodegradation of p-nitrobenzoate and inhibition by benzoate in a pseudomonad; Haller HD et al.; The degradation of p-nitrobenzoate (p-NBA) by domestic sewage was inhibited by benzoate, and a model for this behavior was found in a soil isolate . The isolate, a pseudomonad, utilized p-NBA and benzoate by separate adaptive enzyme pathways . In oxygen uptake experiments, the degradation of p-NBA was competitively inhibited by benzoate, but the degradation of benzoate was not affected by the presence of p-NBA . 4-Nitrocatechol was not implicated in the inhibition . p-Hydroxybenzoate, which is the p-NBA degradation pathway, also had a decreased rate od degradation when benzoate was present . The growth rate of the isolate on the aromatic substrates and on glucose autoclaved in the medium was 0.3 h-1 . When glucose was autoclaved separately, the growth rate was less, about 0.2 h-1 . The apparent Km in oxygen uptake experiments was 25 micrometer for p-NBA and benzoate and 5 micrometer for p-hydroxybenzoate.

Environ Health Perspect, 1978 Apr, 23, 1 - 8
Field concentrations and persistence of polybrominated biphenyls in soils and solubility of PBB in natural waters; Jacobs LW et al.; Soil samples were collected from 28 fields which had received manure from Michigan's most highly contaminated dairy herds . The number of fields in each concentration range of PBB in soil were: 2, not detectable; 15, 0.0 to 8.0 ppb; 6, 14-102 ppb, and 5, 153 to 371 ppb . Plant tissue sampled from the 10 most highly contaminated fields contained no detectable PBB . No evidence of significant degradation of PBB was noted after 1 year incubation in soil . When 14C hexabromobiphenyl and heptabromobiphenyl isomers were incubated in soil less than 0.2% of the 14C was volatilized . Also gas chromatographic analysis of soil extracts showed no difference in recovery of the six major PBB isomers between sterilized and nonsterilized soil . Analysis of these extracts by thin layer chromatography and autoradiography showed no 14C-PBB intermediates . Photodegradation products of the major hexa- and heptabromobiphenyl isomers showed more but still minor (approximately 3%) biodegradation in soil . Much of the photodegradation products appeared bound to soil, since these products could not be extracted from soil . Photodegradation does not appear to be a significant fate of PBB in manures spread on fields since no change was noted in the relative concentrations of isomers in soil samples from our field survey . Studies with distilled, tap, river, and soil waters showed that PBB solubility was markedly influenced by water composition.

Z Allg Mikrobiol, 1978, 18(3), 183 - 8
Microbial biodegradation of cellophase; Lamot E et al.; The microbial biodegradation of cellophane (U.C.B.--Division Sidac) was studied . Preliminary experiments with pure cultures of seven cellulolytic microorganisms (Aspergillus sp., Penicillium sp., Chaetomium crispatum, Ch . globosum, Sclerotium rolfsii and two actinomycetes) revealed that the substrate as such was very recalcitrant, probably due to the occurrence of insoluble coating agents . Therefore, mixed cultures of the above mentioned cellulolytic microorganisms were used as inoculum . The cellophane showed a slow microbial degradation which starts only after 37 days of incubation . This long lag-phase is due to the unaltered presence of the coating agents . However, when the coating agents are extracted with tetrahydrofuran, the biodegradation starts after 10 days, resulting in a biodegradation rate of 85% after 52 days of incubation and a protein content of 30% . The endproduct (30% protein, 60% soluble sugars, 10% residual substrate) will probably be useful as compost.

Ecotoxicol Environ Saf, 1977 Dec, 1(3), 407 - 25
Comparative ecotoxicology of halogenated hydrocarbon residues; Winteringham FP; The term ecotoxicology is adopted in the sense of a comparative and integrated study of the undesirable effects of trace contaminants on the range of fauna and flora of an "ecosystem" or of a defined part or unit thereof . The importance of population changes over long periods of time is stressed . Sources, usage, and global trends of representative halogenated hydrocarbon (HHC) residues which appear as trace contaminants of environment, food, and living organisms are briefly compared: industrial solvents and intermediates, chlorofluoromethanes as an atmospheric pollutant, methyl bromide as a food and soil residue, HCH (hexachlorobenzene) as a fungicide residue, DDT, lindane (gamma-hexachlorocyclohexane), and dieldrin as insecticide residues, and polychlorinated biphenyls (PCBs) as industrial contaminants . A simple mathematical approach to the problem of relating inputs, persistence, and steady-state residue levels is explained . Persistence and biodegradation of representative compounds are compared . Attention is drawn to the persistence of hexachlorobenzene, the p,p'-dichlorodiphenyl- and hexachlorocyclopentadiene-derived moities of HHC residues . Ecotoxicological effects and their implications are discussed comparatively under the indirect effects of atmospheric pollutants and direct and indirect effects of trace contaminants of soil and aquatic ecosystems . Some conclusions related to research and "impact monitoring" are drawn.

Jpn J Antibiot, 1977 Dec, 30 Suppl, 275 - 85
Some observations on biodegradation of pollutants in aquatic systems; Bohonos N et al.; The biodegradability of pollutants introduced into aquatic environments is subject to many variabilities characteristic of microbial processes . Some observations have been reported on studies with p-cresol, methyl parathion, benzo{b}thiophene, dibenzothiophene, 9H-carbazole, quinoline, benzo{f}quinoline, benz{a}anthracene, benzo{a}pyrene, 7H-dibenzo{c,g}carbazole, Mirex, 2,4-dichlorophenoxyacetic acid, Lindane and 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane analogs . Water reservoirs included a eutrophic stream, a eutrophic pond, an oligotrophic lake and effluents from waste-water treatment plants . The first ten of the above compounds were studied only in aerobic mixed-culture systems, and Mirex was studied with mixed cultures under both aerobic and anaerobic conditions . Examples were presented of the significance of cometabolism, diauxic processes, film fermentations and microbial interactions in biodegradation studies . Caution is advised in protocols regarding biodegradability of pollutants in aquatic environments.

J Bacteriol, 1977 Nov, 132(2), 385 - 91
Role of threonine dehydrogenase in Escherichia coli threonine degradation; Potter R et al.; Threonine was used as nitrogen source by Escherichia coli K-12 through a pathway beginning with the enzyme threonine dehydrogenase . The 2-amino-3-ketobutyrate formed was converted to glycine, and the glycine was converted to serine, which acted as the actual nitrogen donor . The enzyme formed under anaerobic conditions and known as threonine deaminase (biodegradative) is less widespread than threonine dehydrogenase and may be involved in energy metabolism rather than in threonine degradation per se.

J Bacteriol, 1977 Nov, 132(2), 370 - 6
Requirements for induction of the biodegradative threonine dehydratase in Escherichia coli; Egan RM et al.; Synthesis of the biodegradative L-threonine dehydratase in Escherichia coli, Crookes strain, was prevented by dissolved oxygen concentrations of 6 micrometer or greater . This effect was shown to be exerted solely on synthesis, rather than being the result of enzyme inactivation in vivo . In addition to an anaerobic environment, maximum enzyme synthesis was dependent upon the presence of a complete complement of amino acids, with omission of L-threonine, L-valine, or L-leucine producing the largest decreases in enzyme formation . L-Threonine, the most essential of the amino acid requirements, could be partially replaced by DL-allothreonine or alpha-ketobutyrate . Half-maximal stimulation of enzyme synthesis occurred with 0.4 mM threonine in the medium . The roles of anaerobiosis and amino acids are interpreted as being in accord with the concept that threonine dehydratase functions in anaerobic energy production under conditions of amino acid sufficiency.

Can Anaesth Soc J, 1977 Nov, 24(6), 641 - 50
Sodium nitroprusside: factors which attenuate its action . Studies with the isolated gracilis muscle of the dog; Tremblay NA et al.; In a laboratory preparation of the isolated, acutely denervated, and separately perfused canine gracilis muscle we have made the following observations: 1 . At physiological pH, sodium nitroprusside significantly decreases the vascular resistance; 2 . At physiological pH, cyanide significantly attenuates the effect of sodium nitroprusside; 3 . In an acidaemic milieu, our data suggest that the effect of sodium nitroprusside may be attenuated . We speculate that patients who manifest resistance to the hypotensive effect of sodium nitroprusside may not normally eliminate the cyanide that is released from the biodegradation of sodium nitroprusside . They accumulate free cyanide which interferes with the action of sodium nitroprusside at the receptor level, leading to administration of more nitroprusside and setting in motion a positive feedback vicious cycle . When one is faced with the problem of an abnormal response to sodium nitroprusside in a fit patient, although many factors may be involved, we suggest that the possibility of rising blood cyanide levels and acidosis be given high priority.

Can J Microbiol, 1977 Oct, 23(10), 1327 - 33
Response of microbial populations in arctic tundra soils to crude oil; Sexstone AJ et al.; Experimental crude oil spillages of 5 and 12 litre/m2 were established on the four major topographically distinguished soils of Arctic coastal polygonized tundra . The response of microbial populations to contaminating oil was found to depend on soil type and depth . Increases in numbers of heterotrophs were initially restricted to the top 2 cm of the soils . Increase in oil-degrading populations were found in oil-treated soils . Increases in microbial populations in subsurface soils paralleled downward migration of the oil . Some of the observed population increases probably resulted from input of plant residues and products from oil biodegradation.

Ann Microbiol (Paris), 1977 Aug-Sep, 128(2), 271 - 87
{Influence of clay on microorganisms conservation . I . Ultrastructural study of the biodegradation of Beauveria bassiana (Bals) . Vuill . (entomopathogenous hyphomycete) in soil (author's transl)}; Reisinger O et al.; Blastospores of B . bassiana enclosed in fine mesh bags were submitted to soil microflora . Clay minerals coating fungal spores protected from by decreasing bacterial activity . The role of amoeba in biodegradation of fungi is also considered.

Nurs Clin North Am, 1977 Jun, 12(2), 291 - 303
The liver: a pharmacologic perspective; Bossone CM; One of the may vital functions of the liver is the biodegradation of foreign substances . The enzyme systems responsible for this liver function are frequently the site of drug interactions, both therapeutic and detrimental . Various substances can alter these enzymes by inducing, inhibiting, or competing with them, thus affecting drug response . In most instances, the liver detoxifies and deactivates chemicals, protecting the body from their harmful effects . In some biotransformation processes, however, toxic metabolites are produced that may be injurious to liver tissue as well as other body organs and systems . The effect of alcohol on the liver is a prime example . Although significant strides have been made in recent years, much is yet to be learned concerning the effect of the liver on drugs, the effect of drugs on the liver, and the pharmacologic management of various liver diseases.

Biochemistry, 1977 Apr 19, 16(8), 1580 - 4
Comparison of the biosynthetic and biodegradative ornithine decarboxylases of Escherichia coli; Applebaum DM et al.; Biosynthetic ornithine decarboxylase was purified 4300-fold from Escherichia coli to a purity of approximately 85% as judged by polyacrylamide gel electrophoresis . The enzyme showed hyperbolic kinetics with a Km of 5.6 mM for ornithine and 1.0 micronM for pyridoxal phosphate and it was competitively inhibited by putrescine and spermidine . The biosynthetic decarboxylase was compared with the biodegradative ornithine decarboxylase {Applebaum, D., et al . (1975), Biochemistry 14, 3675} . Both enzymes were dimers of 80 000-82 000 molecular weight and exhibited similar kinetic properties . However, they differed significantly in other respects . The pH optimum of the biosynthetic enzyme was 8.1, compared with 6.9 for the biodegradative . Both enzymes were activated by nucleotides, but with different specificity . Antibody to the purified biodegradative ornithine decarboxylase did not cross-react with the biosynthetic enzyme . The evolutionary relationship of these two decarboxylases to the other amino acid decarboxylases of E . coli is discussed.

J Biol Chem, 1977 Apr 10, 252(7), 2206 - 8
Subunit structure of biodegradative threonine deaminase; Saeki Y et al.; The molecule weight of the biodegradative threonine deaminase from Escherichia coli was determined to be approximately 147,000 by sedimentation equilibrium ultracentrifugation . Similar experiments using 5 M guanidinium chloride gave a value of 39,000 for the molecular weight of the enzyme subunit . On sodium dodecyl sulfate-gel electrophoresis the enzyme also dissociated into a single subunit with an estimated molecular weight of 38,000 . The NH2 terminus of the enzyme was determined to be methionine by the dinitrophenylation procedure . Quantitative analysis revealed that 3.6 mol of methionine were detected per 147,000 g of enzyme . The selective tritium labeling method established alanine as the COOH-terminal residue . The sequence of residues at the NH2 terminus, determined using an automated sequence analyzer, was: (formula: see text) . The fact that a single amino acid was released at each degradation step in the above experiment strongly suggests that the subunits in the enzyme contain the same amino acid sequence . Therefore, the native enzyme with a molecular weight of 147,000 appears to be composed of four identical polypeptide subunits.

Can J Microbiol, 1977 Apr, 23(4), 434 - 40
Degradation of natural and Kraft lignins by the microflora of soil and water; Crawford DL et al.; The comparative rates of microbial degradation of 14C-lignin-labeled lignocelluloses and 14C-Kraft lignins were investigated using selected soil and water samples as sources of microorganisms . Natural lignocelluloses containing 14C primarily in their lignin components were prepared by feeding plants uniformly labeled L-{14C}phenylalanine through their cut stems . 14C-Kraft lignins were prepared by pulping lignin-labeled lignocelluloses . Rates of lignin biodegradation were determined by monitoring 14CO2 evolution from incubation mixtures over incubation periods of up to 1000 h . Observed rates of lignin degradation were slow in all cases . Kraft lignins appeared more resistant to microbial attack than natural lignins, even though they were decomposed more rapidly during the first 100-200 h of incubation . Similar degradation patterns were observed in both soil and water . Individual samples, however, varied greatly in their overall rates of degradation of either lignin type . A Kraft-lignin preparation was separated into a variety of molecular weight fractions by column chromatography on LH-20 Sephadex and the biodegradability of the different molecular weight fractions determined . The lower molecular weight fractions of the Kraft lignin were decomposed at a significantly faster rate by the microflora of soil than were the fractions of higher molecular weight.

Fed Proc, 1977 Apr, 36(5), 1736 - 41
Urticaria, angioedema, and mediator release in humans in response to physical environmental stimuli; Soter NA et al.; The activation of mast cells by immunologic or physical stimuli leads to the generation of unstored intermediates (mediators) such as slow reacting substance of anaphylaxis (SRS-A) and platelet activating factor (PAF), and to their release along with performed mediators, histamine, eosinophil chemotactic factor of anaphylaxis (ECF-A), and neutrophil chemotactic factor (NCE), and macromolecular heparin . The internal regulation of mast cell-dependent phenomenons occurs at at least four levels: 1) the intensity and nature of the activating stimulus, 2) the regulation of mediator generation and release of cellular levels of the cyclic nucleotides, 3) the capacity of target cells to bind and respond to primary mediators, and 4) the rate at which mediators undergo biodegradation . Inasmuch as the mast cell is present at cutaneous and mucosal surfaces about venules, it seems likely that the initial or humoral phase of its response achieves an influx of plasms proteins, such as immunoglobulins and complement components, whereas the subsequent cellular phase augments local host defense through the entrance of neutrophils and eosinophils that terminate the humoral phase . The activation of mast cells is considered herein in terms of defined physical stimuli that are characterized by urticaria and angioedema.

Can J Microbiol, 1977 Mar, 23(3), 230 - 9
Metabolism of monoterpene alcohol, linalool, by a soil pseudomonad; Madyastha K et al.; A microorganism of the genus Pseudomonas has been isolated from the soil by enrichment culture techniques with linalool(I) as the sole source of carbon and energy . The organism is also capable of utilizing limonene, citronellol, and geraniol as substrates but fails to grow on citral, critranellal, and 1,8-cineole . Fermentation of linalool by this bacterium in a mineral salt medium results in the formation of 10-hydroxylinalool(II), oleuropeic acid (IX), 2-vinyl-2-methyl-5-hydroxyisopropyl-tetraphydrofuran)linalool oxide, V), 2-vinyl-2-methyl-tetrahydrofuran-5-one(unsaturated lactone, VI), and few unidentified minor metabolities . Probable pathways for the biodegradation of linalool are presented.

J Clin Invest, 1977 Mar, 59(3), 443 - 8
Enzymatic basis for bioenergetic differences of alveolar versus peritoneal macrophages and enzyme regulation by molecular O2; Simon LM et al.; Alveolar macrophages (AM) and peritoneal macrophages (PM) originate from common precursor cells, but function in different O2 environments . In the present studies, the impact of different O2 tensions on cell metabolism has been quantitatively determined, an enzymatic basis for these differences established, and a mechanism which regulates enzymatic differences demonstrated . O2 consumption and lactate production were compared in rabbit AM and PM in air and nitrogen . In air, AM demonstrate significantly greater O2 utilization . In nitrogen, (where glycolysis is the major source of energy provision) lactate production is two- to threefold greater in the PM . A comparison of several enzymes of energy metabolism in AM and PM indicate that one basis for the differences in cell energetics is a difference in activity of key enzymes of both the oxidative phosphorlyative and the glycolytic sequences . Exposure of cultivated AM to hypoxic conditions results in changes in the activity of these enzymes such that the AM closely resembles the PM . A key enzyme in oxidative phosphorylation (cytochrome oxidase) shows decreased activity and reaches values similar to those found in the PM . A key enzyme in glycolysis (pyruvate kinase) shows increased activity to values resembling those found in the PM . These alterations in enzyme pattern occur in isolated cell systems, suggesting that molecular O2 modifies the intrinsic cellular regulation of some enzymes of energy metabolism . Alterations in O2 tension may lead to alterations of the rate of biosynthesis and (or) the rate of biodegradation of key enzymes involved in oxidative phosphorylation and glycolysis . In turn, the alteration of enzyme patterns leads to a more suitable bioenergetic pattern as a function of O2 availability.

Cancer Lett, 1977 Mar, 2(4-5), 279 - 84
Protein bound carboxyl-methyl ester as a precursor of methanol formation during oxidation of dimethylnitrosamine in vitro; Kim S et al.; Protein modification with dimethylnitrosamine was studied in vitro in the presence of hamster liver microsomal fraction . Incorporation of radioactive methyl groups from dimethylnitrosamine into the exogenously added protein was dependent on the microsomal mixed function oxidase system . The methylation yielded chemically labile and stable products . The former was completely hydrolyzed by the mild alkaline treatment, pH 7.4, 100 degrees C, for 5 min and the hydrolytic product was identified as methanol indicating that the activated methyl groups from dimethylnitrosamine were incorporated into a protein as a carboxyl-methyl ester . Thus, it is suggested that methanol, recovered as one of the products during the biodegradation of dimethylnitrosamine {8}, is derived, at least in part, from protein carboxyl-methyl ester which is unstable under physiological conditions.

Rev Electroencephalogr Neurophysiol Clin, 1977 Jan-Mar, 7(1), 117 - 23
{Electroencephalographic features during enflurane anaesthesia in older children (author's transl)}; Trapp C et al.; The authors report electroclinical changes observed during Enflurane anaesthesia, at various concentrations, in 25 children aged 4 to 14 years . EEG features are described from induction to surgical anesthesia (concentration 3-3.5%) and during overdoses (4-4.5%) with or without hyperventilation . Groups of spikes, low voltage sequences and electroclinical "seizures" (2 cases) only occur if the concentration of enflurane is not kept below 3.5% . A longitudinal study (24th hour, 3rd and 6th day) shows, by comparison with the pre-anaesthetic EEG, persistence in all cases of EEG slowing 24 hours after the anaesthesia, and in some patients EEG disturbances continue until the 6th day . These results are discussed in relation to data on the biodegradation of enflurane.

Zentralbl Bakteriol Parasitenkd Infektionskr Hyg, 1977, 132(5-6), 423 - 33
{Biodegradation of the mycelium of Pyrenochaeta lycopersici Schneider et Gerlach in the soil . Ultrastructural study}; Harranger MF et al.; Under natural conditions, Pyrenochaeta lycopersici forms a sterile mycelium . Some strains form chlamydospores, while others form micro-sclerotia . The fungus survives by hyphae cells which are present in soil either free-living or momentarily protected by the tissue of the infected root . In a model experiment, the behaviour of the free mycelium was tested in a soil which had been supplied with asparagine and manure, respectively . A known quantity of living mycelium was added to the prepared soils . Samples were taken after 1, 3, 6, and 10 months . They were examined on loss of weight of the mycelium, inoculum potential, and ultra-structure of the hyphae before and during degradation by transmission electron microscopy.

J Bioeng, 1977 Jan, 1(2), 93 - 7
Tri-calcium phosphate as a bone substitute; Rejda BV et al.; Strong porous tri-calcium phosphate ceramic has been fabricated, and investigated as a bone implant material . No foreign body reaction was observed, while osteoclastic activity was shown to be involved in biodegradation . Bone mineral was deposited directly onto the surface of the ceramic implant.

Naunyn Schmiedebergs Arch Pharmacol, 1976 Dec 29, 296(1), 67 - 72
Biodegradation of alpha-hexachlorocyclohexane . VII . Resolution, purification, and characterization of an alpha-HCH dechlorinating enzyme from rat liver cytosol; Kraus P; From rat liver cytosol, an enzyme was isolated which catalyzes the dechlorination of alpha-, gamma-, and delta-HCH . The enzyme also catalyzes the conjugation of GSH with 1,2-dichloro-4-nitrobenzene, and with 1 -chloro-2,4-dinitrobenzene . The enzyme has a molecular weight of about 46000 and its molecule is composed of two subunits of similar size . The optimum for the dechlorination of alpha-HCH lies at pH 8.0 . The Michaelis constant is 0.12 mM for alpha-HCH (with 1 mM GSH as constant substrate), and maximal velocity was determined to be 0.25 moles Cl- -min -1 per mole enzyme.

JAMA, 1976 Dec 20, 236(25), 2859 - 62
Human umbilical cord . A new source for vascular prosthesis; Dardik H et al.; Reconstructions were performed to the popliteal, tibial, and peroneal arteries employing a modified umbilical cord vein prosthesis . The latter was obtained from human cords and was made available as an onshelf graft for surgery following glutaraldehyde tanning . The early patency and limb salvage rates are equivalent to those obtained with autogenous saphenous veins . Additional benefits include significant decreased operative time and morbidity . It is also probable that this new graft may be resistant to biodegradation and therefore may obviate many of the causes for late failure that occur with the use of living biologic tissues or collagen tubes . Long-term follow-up and study are essential to validate the results obtained thus far and to assess the potential of this new graft in a variety of vascular reconstructions.

Brain Res Bull, 1976 Nov-Dec, 1(6), 591 - 3
Biodegradation of alpha-MSH and derived peptides by rat brain extracts, and by rat and human serum; Marks N et al.; The peptides alpha-MSH and MSH/ACTH 4-10 were degraded by rat brain extracts and serum to yield free amino acids among the end-products . Breakdown of these two peptides was double that of a related synthetic hexapeptide Met (0)-Glu-His-Phe-D-Lys-Phe . No significant breakdown of the hexapeptide occurred after incubation with human serum; it also had almost negligible pigmentary effects in vivo and in vitro when compared to alpha-MSH . The patterns of amino acid release indicate possible endopeptidase cleavage at Phe-Arg in alpha-MSH followed by secondary exopeptidase action to release free amino acids . For the hexapeptide, the primary cleavage point occurred at the -His3-Phe4 bond . The stability of this analog in human sera, coupled with its lower rate of degradation in the CNS, may contribute to its more potent behavioral actions in vivo.

Can J Microbiol, 1976 Aug, 22(8), 1209 - 13
Biodegradation rates of components of petroleum; Walker JD et al.; Rates of microbial biodegradation of components of South Louisiana crude oil were determined by computer analysis of data obtained from computerized mass spectrometry . Total residue of the oil decreased exponentially with time, with maximum decrease noted at logarithmic phase, whereas asphaltenes and resins increased at the logarithmic phase of growth . Saturates decreased continuously during growth . Microbial degradation of components of crude oil was concluded to be a dynamic process.

Appl Environ Microbiol, 1976 May, 31(5), 764 - 72
Environmental factors influencing the rate of hydrocarbon oxidation in temperate lakes; Ward DM et al.; Rates of hydrocarbon biodegradation were estimated by following oxygen uptake during mineral oil oxidation or oxidation of {1-14C}hexadecane to 14CO2, when these substrates were added to natural water samples from Wisconsin lakes . A lag phase preceded hydrocarbon oxidation, the length of which depended on population density or on factors influencing growth rate and on the presence of nonhydrocarbon organic compounds . Hydrocarbon oxidation was coincident with growth and presumably represented the development of indigenous hydrocarbon-degrading microorganisms in response to hydrocarbon additions . In detailed studies in Lake Mendota, it was found that, despite the continued presence of hydrocarbon-degrading microorganisms in water samples, seasonal variations in the rates of mineral oil and hexadecane oxidation occurred which correlated with seasonal changes in temperature and dissolved inorganic nitrogen and phosphorus . The temperature optimum for oil biodegradation remained at 20 to 25 C throughout the year, so that temperature was the main limiting factor during winter, spring, and fall . During summer, when temperatures were optimal, nutrient deficiencies limited oil biodegradation, and higher rates could be obtained by addition of nitrogen and phosphorus . The rates of hydrocarbon biodegradation were thus high only for about 1 month of the ice-free period, when temperature and nutrient supply were optimal . Nutrient limitation of oil biodegradation was also demonstrated in 25 nutrient-poor lakes of northern Wisconsin, although in almost every case oil-degrading bacteria were detected . Knowledge of temperature and nutrient limitations thus will help in predicting the fate of hydrocarbon pollutants in freshwater.

Appl Environ Microbiol, 1976 May, 31(5), 629 - 34
Microbial degradation of oil spills enhanced by a slow-release fertilizer; Olivieri R et al.; The improved cleanup of marine oil spills by stimulating biodegradation through the use of a slow-release fertilizer is reported . A paraffin-supported fertilizer containing MgNH4PO4 as active ingredient was developed and evaluated in laboratory and field experiments using quantitative infrared spectrometry and chromatographic techniques . The biodegradation of Sarir crude oil in the sea was considerably enhanced by paraffin-supported fertilizer . After 21 days 63% had disappeared as compared to 40% in the control area.

Arch Psychiatr Nervenkr, 1976 Apr 30, 221(3), 213 - 25
{Sphingolipid storage disease as an example of a molecular neuropathology (author's transl)}; Jatzkewitz H et al.; A short survey on the sphingolipid storage diseases is presented . The chemical nature of the accumulated substances is related to the genetically induced enzymic blocks on their biodegradation . Two disorders are stressed with alter the nervous system: metachromatic leukodystrophy and familiar infantile amaurotic idiocy (GM2-gangliosidosis) . The difficulties in the causal interpretation of three variants of the latter disease due to the involvement of isoenzymes are dealt with . The relationship between the enzyme defect in these disorders and their time of clinical onset is discussed . Finally, the diagnostic possibilities are presented which are a prerequisite for preventing a further dissemination of these therapy-resistent inborn errors of metabolism.

Appl Environ Microbiol, 1976 Apr, 31(4), 522 - 35
Oil degradation in soil; Raymond RL et al.; The environmental effects of adding certain selected petroleum products to field soils at widely separated geographical locations under optimum conditions for biodegradation were studied . The locations selected for study of soil biodegradation of six oils (used crankcase oil from cars, used crankcase oil from trucks, an Arabian Heavy crude oil, a Coastal Mix crude oil, a home heating oil no . 2, and a residual fuel oil no . 6) were Marcus Hook, Pennsylvania, Tulsa, Oklahoma, and Corpus Christi, Texas . The investigative process, covering a period of 1 year at each location, was conducted in 14 fields plots (1.7 by 3.0 m) to which the oils were added in a single application at a rate of 11.9 m3/4 X 10(3) m2 . One-half of the plots at each location were fertilized, and the incorporation of the oils and fertilizers was accomplished with rototillers to a depth of 10 to 15 cm . Concentrations of all oils decreased significantly at all locations . The average reduction ranged from 48.5 to 90.0% depending upon the type of oil and location . Rates of degradation did not exceed 2.4 m3/4 X 10(3) m2 per month . Compositional changes in the oil with time were investigated using silica gel fractionation, gas chromatography, and ultraviolet absorbance . With the possible exception of the two fuel oils, the compositional changes were generally in the same direction for all of the oils . The silica gel fractionation and gravimetric data on residual oils show that all classes of compounds were degraded, but the more polar type degrade more slowly . Analysis of runoff water, leachate, and soils indicated that at the concentration applied no oil less was observed from these plots via water movement . No significant movement of lead compounds added to the soils in the used crankcase oils was observed . Significant increases in hydrocarbon-utilizing microorganisms were demonstrated in all treated plots using either the pure hydrocarbon, n-hexadecane, or the applied oils as the growth substrate . These increases were usually sustained throughout the year . Significant increases in hydrocarbon-utilizing fungi were not demonstrated by the plating technique used . The concentrations of residual oils or their oxidation products were of sufficient magnitude in the treated plots, 9 months after application, to cause significant inhibition of plant growth . From the data obtained, it was not possible to determine the type of compounds causing this inhibition or their long-term environmental effects.

Appl Environ Microbiol, 1976 Apr, 31(4), 544 - 50
Effect of iron on the biodegradation of petroleum in seawater; Dibble JT et al.; The biodegradation of South Louisiana (SL) crude oil and the effects of nitrogen, phosphorus, and iron supplements on this process were compared in a polluted (10,900 oil degraders per liter) and in a relatively clean (750 oil degraders per liter) littoral seawater sample taken along the New Jersey coast . Without supplements, the biodegradation of SL crude oil was negligible in both seawater samples . Addition of nitrogen and phosphorus allowed very rapid biodegradation (72% in 3 days) in polluted seawater . Total iron in this seawater sample was high (5.2 muM), and the addition of iron did not increase the biodegradation rate further . In the less polluted and less iron-rich (1.2 muM) seawater sample, biodegradation of SL crude oil was considerably slower (21% in 3 days) and the addition of chelated iron had a stimulating effect . Ferric octoate was shown to have a similar stimulating effect on SL crude oil biodegradation as chelated iron . Ferric octoate, in combination with paraffinized urea and octylphosphate, is suitable for treatment of floating oil slicks . We conclude that spills of SL crude and similar oils can be cleaned up rapidly and efficiently by stimulated biodegradation, provided the water temperatures are favorable.

Environ Health Perspect, 1976 Apr, 14, 15 - 28
Degradation, metabolism and toxicity of synthetic pyrethroids; Miyamoto J; Synthetic pyrethroidal compounds undergo biodegradation in mammals both oxidatively and hydrolytically, and depending on the type of compound, either of the pathways may predominate . Thus, (+) - or (+/-) -trans isomers of the chrysanthemumate ester of primary alcohols such as fenothrin, furamethrin, proparthrin, resmethrin, and tetramethrin (and possibly permethrin, too) are metabolized mainly through hydrolysis of the ester linkage, with subsequent oxidation and/or conjugation of the component alcohol and acid moieties . On the other hand, the corresponding (+)-cis enantiometers and chrysanthemumate of secondary alcohols like allethrin are resistant to hydrolytic attack, and biodegraded via oxidation at various sites of the molecule . These rapid metabolic degradations, together with the presumable incomplete absorption from the gastrointestinal tract, would generally contribute to the low acute toxicity of synthetic pyrethroids . These compounds are neither skin irritants nor skin sensitizers, and inhalation toxicity as well as dermal toxicity are fairly low . Neither is teratogenic in rats, mice, and/or rabbits or mutagenic on various bacterial strains . Subacute and chronic feeding of higher amounts of the compounds to rats invariably causes some histopathological changes in liver; however, these are neither indicative nor suggestive of tumorigenicity . Based on existing toxicological information, the present recommended use patterns might afford sufficient safety margin on human population . However, in extending usage to agricultural pest control, much more extensive investigations should be forthcoming from both chemical and biological aspects, since there is scant information on the fate of these pyrethroids in the environment . Also several of the compounds may be very toxic to certain kinds of fish and arthropods.

J Bacteriol, 1976 Apr, 126(1), 100 - 7
Threonine deaminase from a nonsense mutant of Escherichia coli requiring isoleucine or pyridoxine: evidence for half-of-the-sites reactivity; Feldner J et al.; The mutant IP7 of Escherichia coli B requires isoleucine or pyridoxine for growth as a consequence of a mutation in the gene coding for biosynthetic threonine deaminase . The mutation of IP7 was shown to be of the nonsense type by the following data: (1) reversion to isoleucine prototrophy involves the formation of external suppression at a high frequency, as shown by transduction experiments; and (ii) the isoleucine requirement is suppressed by lysogenization with a phage carrying the amber suppressor su-3 . Cell extracts of the mutant strain contain a low activity of threonine deaminase . The possibility that this activity is biodegradative was ruled out by kinetic experiments . The mutant threonine deaminase was purified to homogeneity by conventional procedures . The enzyme is a dimer of identical subunits of an approximate molecular weight of 43,000 (Grimminger and Feldner, 1974), whereas the wild-type enzyme is a tetramer of 50,000-dalton subunits (Calhoun et al., 1973; Grimminger et al., 1973) . The mutant enzyme is not inhibited by isoleucine and does not bind isoleucine, as shown by equilibrium dialysis experiments . Pyridoxal phosphate enhances the maximum catalytic activity of the mutant enzyme by a factor of five, whereas the wild-type enzyme is not affected . In wild-type and mutant threonine deaminase the ratio of protein subunits and bound pyridoxal phosphate is 2:1 . The activation of threonine deaminase from strain IP7 is due to a second coenzyme binding site, as shown by (i) spectrophotometric titration of the enzyme with pyridoxal phosphate and by (ii) measurement the pyridoxal phosphate content of the enzyme after sodium borohydride reduction of the protein . The observation of one pyridoxal phosphate binding site per peptide dimer in the wild-type enzyme and of two binding sites per dimer in the mutant strongly suggests that one of the potential sites in the wild-type enzyme is masked by allosteric effects . The factors responsible for the half-of-the-sites reactivity of the coenzyme sites appear to be nonoperative in the mutant protein.

J Bacteriol, 1976 Feb, 125(2), 601 - 7
Arginine decarboxylase from a Pseudomonas species; Rosenfeld HJ et al.; An arginine decarboxylase has been isolated from a Pseudomonas species . The enzyme is constitutive and did not appear to be repressed by a variety of carbon sources . After an approximately 40-fold purification, the enzyme appeared more similar in its properties to the Escherichia coli biosynthetic arginine decarboxylase than to the E . coli inducible (biodegradative) enzyme . The Pseudomonas arginine decarboxylase exhibited a pH optimum of 8.1 and an absolute requirement of Mg2+ and pyridoxal phosphate, and was inhibited significantly at lower Mg2+ concentrations by the polyamines putrescine, spermidine, and cadaverine . The Km for L-arginine was about 0.25 mM at pH 8.1 AND 7.2 . The enzyme was completely inhibited by p-chloromercuribenzoate . The inhibition was prevented by dithiothreitol, a feature that suggests the involvement of an -SH group . Of a variety of labeled amino acids tested, only L-arginine, but not D-arginine was decarboxylated . D-Arginine was a potent inhibitor of arginine decarboxylase with a Ki of 3.2 muM.

Appl Environ Microbiol, 1976 Jan, 31(1), 7 - 10
Microbiological oxidation of synthetic chalcocite and covellite by Thiobacillus ferrooxidans; Sakaguchi H et al.; The microbiological oxidation of synthetic chalcocite and covellite has been investigated using an adapted strain of Thiobacillus ferrooxidans . Biodegradation of chalcocite was found to be 90 to 100% and that of covellite 45 to 60% . Optimum conditions for the oxidation of chalcocite were: pH, 1.7 to 2.3; temperature, 35 C; and ferric iron concentration in the range of 0.004 to 0.01 M . For covellite, the optimum conditions were: pH 2.3; temperature, 35 C; and ferric iron concentration in the range of 0.004 to 0.02 M . The energies of activation were determined to be 16.3 kcal (ca . 6.8 X 10(4) J) per mol and 11.7 kcal (ca . 4.8 X 10(4) J) per mol for chalcocite and covellite, respectively.

Appl Microbiol, 1975 Dec, 30(6), 922 - 9
Screening test for assessment of ultimate biodegradability: linear alkylbenzene sulfonates; Gledhill WE; A relatively simple shake-flask system for determining CO2 evolution was developed to assess the ultimate biodegradability by soil and sewage micro-organisms of chemicals which enter the environment . Linear alkylbenzene sulfonates (LAS) were used as model compounds to evaluate the method and were found to undergo substantial biodegradation in this dilute system . At the 30 mg/liter test concentration, higher-molecular-weight LAS compounds were biodegraded at a slower rate and to a lesser extent than lower-molecular-weight LAS, an effect which was eliminated or greatly reduced upon incremental addition of the LAS to the test medium during the first week of incubation . LA35S was used to demonstrate rapid LAS desulfonation, and 14CO2 evolution studies with (14C) benzene ring-labeled LAS indicated concomitant biodegradation of the entire LAS molecule as well as the LAS aromatic component . The test can be employed to examine numerous compounds at the same time and is readily adapted to studies of the effect of variation in temperature and oxygen concentration on biodegradation.

Bull Tokyo Med Dent Univ, 1975 Dec, 22(4), 263 - 72
Interaction between polymeric materials and tissue -- biodeterioration of polymeric materials; Kojima K; Styrene-isoprene block copolymer/methyl methacrylate graft copolymer (SIS-MMA), styrene-butadiene block copolymers (SBS), polyethylene, 1,2-polybutadiene, polysulfone, polycaprolactone polyurethane (PU) and ethylene-vinyl acetate copolymer (EVA) were implanted subcutaneously in dogs for 1 year . The same materials were stored in physiological saline solution at 37 degrees C (in vitro) and in air at room temperature (in air) for 1 year for comparative purpose . Biodeterioration or biodegradation of these materials was studied by mechanical property testing, viscometry, x-ray diffractometry, infrared spectroscopy and microscopy . A little deterioration of the mechanical properties of all the implanted samples was noticed as compared with the samples stored in vitro and in air . The infrared spectrum and x-ray diffraction pattern of the implanted sample except SIS-MMA were practically identical with the control . The implanted samples of SIS-MMA and SBS showed a cracked surface under a differential interference microscope . Viscosity measurements suggested a possible main chain scission for SIS-MMA and cross-linking for SBS and showed that the molecular weight of the other materials was almost unchanged . The intactness was rather surprising in regard to the infrared spectrum and viscosity of PU and EVA, because they were supposed to be more biodegradable . Deterioration of the mechanical properties was not always due to the results of biodegradation, as is often believed, but it must be considered that it might also be due to the absorption of some constituents such as lipids, steroids and amino acid from the body fluids and/or leaching of low molecular weight substances from the implanted materials.

Naunyn Schmiedebergs Arch Pharmacol, 1975 Nov 3, 291(1), 79 - 87
Biodegradation of alpha-hexachlorocyclohexane . VI . The cechlorination of alpha-hexachlorocyclohexane by microsomes and cytosol of rat liver; Kraus P; Alpha-hexachlorocyclohexane (alpha-HCH) is dechlorinated by enzymes contained in rat liver cytosol and microsomes . An evidence was obtained that in the cytosol there are two alpha-HCH dechlorinating enzymes at least; one operates only in the presence of reduced glutathione (GSH) and catalyzes dechlorinations associated with the formation of another hydrophilic product . This product is probably a conjugate of the alpha-HCH-residue with GSH . The other cytoplasmic alpha-HCH-dechlorinase requires no additions . The microsomes, too, contain two alpha-HC dechlorinases at least: one is stimulated by GSH, the other by NADPH.

Ann N Y Acad Sci, 1975 Sep 30, 258, 132 - 43
Ascorbic acid requirements and metabolism in relation to organochlorine pesticides; Street JC et al.; Those organochlorine pesticides which possess both high lipoid solubility and high resistance to biodegradation are prone to accumulation in animal tissues and produce relatively long-term effects as toxicants . Such compounds, typified by DDT, Dieldrin, and Lindane, are profound inducers of hepatic microsomal enzymes, including parts of the glucuronic acid and ascorbic acid biosynthetic pathways . Consequently, administering such pesticides to rats in accompanied by enhanced formation and excretion of D-glucuronic acid and L-ascorbic acid, or D-glucaric acid in the case of guinea pigs . Secondarily, the efficiency in biodegrading the pesticides is reduced in ascorbic-acid-deficient guinea pigs with correspondingly greater residue accumulation in tissue . This would aggravate chronic toxic effects of the compounds . Finally, the capacity of the liver to adapt to the presence of such toxicants through enhanced microsomal enzymatic levels appears to be sensitive to its ascorbate status . Impaired enzyme induction is apparent quite early during ascorbic acid depletion in guinea pigs . The enhanced turnover of ascorbate produced by such pesticides, the poor enzymatic adaptation to them during ascorbate depletion and the dependency of the oxidase system upon adequate ascorbate, all point to the central significance of ascorbate status in the liver, and possibly other tissues, as a determinant of their chronic toxicity.

Appl Microbiol, 1975 Sep, 30(3), 396 - 403
Effects of temperature and crude oil composition on petroleum biodegradation; Atlas RM; The biodegradability of seven different crude oils was found to be highly dependent on their composition and on incubation temperature . At 20 C lighter oils had greater abiotic losses and were more susceptible to biodegradation than heavier oils . These light crude oils, however, possessed toxic volatile components which evaporated only slowly and inhibited microbial degradation of these oils at 10 C . No volatile toxic fraction was associated with the heavier oils tested . Rates of oil mineralization for the heavier oils were significantly lower at 20 C than for the lighter ones . Similar relative degradation rates were found with a mixed microbial community, using CO2 evolution as the measure, and with a Pseudomonas isolate from the Arctic, using O2 consumption as the measure . The paraffinic, aromatic, and asphaltic fractions were subject to biodegradation . Some preference was shown for paraffin degradation, especially at low temperatures . Branched paraffins, such as pristane, were degraded at both 10 and 20 C . At best, a 20% residue still remained after 42 days of incubation . Oil residues generally had a lower relative percentage of paraffins and higher percentage of asphaltics than fresh or weathered oil.

Biochemistry, 1975 Aug 12, 14(16), 3675 - 81
Biodegradative ornithine decarboxylase of Escherichia coli . Purification, properties, and pyridoxal 5'-phosphate binding site; Applebaum D et al.; The biodegradative ornithine decarboxylase of Escherichia coli has been purified to apparent homogeneity . At its pH optimum (pH 7.0), the enzyme exists as a dimer of 160,000 molecular weight . Aggregation of the dimer was promoted by lower pH values . The enzyme requires pyridoxal 5'-phosphate for activity . The coenzyme appears to be bound in Schiff base linkage as suggested by spectral studies and inhibition by NaBH4 . The following sequence was determined for the coenzyme binding site: Val-His-(epsilon-Pxy)Lys-Gln-Gln-Ala-Gly-Gln . The properties of this enzyme are compared with the other biodegradative amino acid decarboxylases that have been isolated from E . coli.

Proc Natl Acad Sci U S A, 1975 Jul, 72(7), 2515 - 9
Preparation and microbial decomposition of synthetic {14C}ligins; Kirk TK et al.; A definitive assay for microbiological and biochemical research on the biodegradation of lignin was developed using radioactive synthetic lignins specifically labeled in the side chains, aromatic rings or in the methoxyl groups . The {14C}lignins were prepared by oxidative polymerization with peroxidase and H2O2 Of specifically labeled coniferyl alcohol (4-hydroxy-3-methyoxycinnamyl alcohol) . The synthetic polymers were shown by spectroscopic and chemical methods to contain the same intermonomer linkages found in natural lignins . Incubation of the {14C}lignins with known lignin-degrading fungi and with a forest soil resulted in 14CO2 evolution.

Appl Microbiol, 1975 Jun, 29(6), 758 - 64
Biodegradation of metal-nitrilotriacetate complexes by a Pseudomonas species: mechanism of reaction; Firestone MK et al.; A nitrilotriacetate (NTA)-degrading Pseudomonas species was shown to degrade Ca, Mn, Mg, Cu, Zn, Cd, Fe, and Na chelates of NTA at nearly equal rates when the appropriate metal concentrations are low enough to avoid toxicity from the freed metal . Ni-NTA, however, was not degraded . When higher concentrations of metal-NTA substrates were used, soil stimulated degradation of Cu, Zn, and Cd complexes, probably as a result of binding toxic freed metals . The metal associated with the NTA substrate does not appear to be transported into the cell, since metals do not accumulate in the cells and the presence of NTA reduces metal toxicity . The data are consistent with the hypothesis that an envelope-associated component, probably a transport protein involved in binding, is responsible for the disassociation of the metal from the NTA . Both soil and this NTA-degrading organism destabilize the metal-NTA complex, which suggests that in the natural environment both would act to limit mobilization of metals as soluble NTA chelates . Crude soluble enzyme preparations degrade Fe-, Mn-, and Na-NTA complexes but not Cu-NTA.

Appl Microbiol, 1975 May, 29(5), 646 - 52
Persistence and biodegradation of spilled residual fuel oil on an estuarine beach; Pierce RH Jr et al.; The enrichment of hydrocarbon-degrading bacteria and the persistence of petroleum hydrocarbons on an estuarine beach after a spill of residual fuel oil on 11 April 1973 in Upper Narragansett Bay, R.I . was investigated . A rapid enrichment occurred during days 4 to 16 after the oil spill and a significant population of hydrocarbon-degrading bacteria was maintained in the beach sand for at least a year . The concentration of petroleum hydrocarbons in the mid-tide area declined rapidly during the bacterial enrichment period, remained fairly constant throughout the summer, and then declined to a low concentration after 1 year . An increased concentration of branched and cyclic aliphatic hydrocarbons in the low-tide sediment 128 days after the spill suggested a migration of hydrocarbons during the summer . Hydrocarbon biodegradation was apparent during the winter months at a rate of less than 1 mug of hydrocarbon per g of dry sediment per day.

J Cardiovasc Surg (Torino), 1975 May-Jun, 16(3), 318 - 21
Early failure of Dacron prosthetic grafts; Perry MO; Crimped knitted Dacron grafts are commonly employed as arterial substitutes and in most instances have proven to be highly effective and relatively durable . Graft failures have occurred and have usually been associated with serious hemorrhage . Fabrication flows, intraoperative damage to the graft, or biodegradation have been suggested as causes of graft failure . In this study three aortic grafts failed, each apparently from a different cause and each presented in a different fashion . Although the exact cause of graft failure in these three cases could not be ascertained it appeared that one was due to a fabrication flow, one due to generalized loss of tensile strength, and the third due to deterioration of only a portion of the fraft . These data suggest that continued search for more suitable plastic prostheses is urgently needed;

Biokhimiia, 1975 May-Jun, 40(3), 645 - 51
{Intermediate plateaux in kinetics of the reaction catalyzed by biodegradative L-threonine dehydratase from Escherichia coli}; Sinelnikova EM et al.; It has been shown that for the reaction catalyzed by "biodegradative" L-threonine dehydratase from E . coli strains K-12 and 980 in 0.5 M phosphate-carbonate buffer, pH 8.4 and pH 9.5, the plots of initial reaction rate (v) versus the initial substrate concentration ({S}0 are characterized by several inflection points, i . e . an intermediate plateau . The plot of v versus the allosteric activator (AMP) concentration have very complicated shapes: there are several inflection points, and also the maximum at L-threonine concentration equal to 3-10(2) and 5-10(-2) M . High AMP concentrations inhibit the enzyme at high substrate concentrations . The reduced glutathion dose not influence the enzyme and does not alter the activating effect of AMP . On the basis of the data obtained it is proposed that the substrate and AMP shift the equilibrium between multiple oligomeric enzyme forms differing in catalytic activity and kinetic manifestations of allosteric interactions between the active and allosteric AMP-binding sites towards polymerization . Thus, the functioning the enzyme under study is discussed in the frames of the model of dissociating regulatory enzymes with multiple intermediate oligomeric forms.

Biochemistry, 1975 Apr 22, 14(8), 1760 - 7
Catabolite inactivation of biodegradative threonine dehydratase of Escherichia coli; Feldman DA et al.; Incubation of Escherichia coli cells with glucose, pyruvate, and certain other metabolites led to rapid inactivation of inducible biodegradative threonine dehydratase . Analysis with several mutant strains showed that pyruvate, and not a metabolite derived from pyruvate, was capable of inactivating enzyme, and that glucose acted indirectly after being converted to pyruvate . Some other alpha-keto acids such as oxaloacetate and alpha-ketobutyrate (but not alpha-ketoglutarate) were also effective . Inactivation of threonine dehydratase by pyruvate was also observed with purified enzyme preparations . The rates of enzyme inactivation increased with increased concentrations of pyruvate and decreased with increased levels of AMP . Increasing protein concentrations lowered the rates of enzyme inactivation . Dithiothreitol had a large effect on the maximum extent of inactivation of the enzyme by pyruvate; high concentrations of AMP and DTT almost completely counteracted the effect of pyruvate . Gel filtration data showed that pyruvate influenced the oligomeric state of the enzyme by altering the association-dissociation equilibrium in favor of dissociation; the Stokes' radius of the pyruvate-inactivated enzyme was 32 A as compared to 42 A for the untreated enzyme . Reassociation of the dissociated form of the enzyme was achieved by removal of excess free pyruvate by dialysis against buffer supplemented with AMP and DTT . Incubation of threonine dehydratase with {14-C}pyruvate revealed apparent covalent attachment of pyruvate to the enzyme . Strong protein denaturants such as guanidine, urea, and sodium dodecyl sulfate failed to release bound radioactive pyruvate; the molar ratio of firmly bound pyruvate was approximately 1 mol/150,000 g of protein . Pretreatment of the enzyme with p-chloromercuribenzoate and 5,5'-dithiobis(2-nitrobenzoate) (Nbs2) did not reduce the binding of {14-C}pyruvate suggesting no active site SH was involved in the pyruvate-enzyme linkage . Titration of active and pyruvate-inactivated enzyme with Nbs2 indicated that the loss in enzyme activity was not due to oxidation of essential sulfhydryl groups on the enzyme . Based on these data we propose that the mechanism of enzyme inactivation by pyruvate involves covalent attachment of pyruvate to the active oligomeric form of the enzyme followed by dissociation of the oligomer to yield inactive enzyme.

Appl Microbiol, 1975 Apr, 29(4), 458 - 63
Fungal air spora at Ibadan, Nigeria; Ogunlana EO; The fungal air spora at Ibadan, Nigeria, was investigated by using Casella Slit Samplers . Three sites, incorporating three locations at each site, were selected for the exposure of replicate plates during sampling . To provide data on a wide range of saprophytic and pathogenic fungal spores, isolations were made on Sabouraud dextrose agar and malt agar plates incubated at 26 and 37 C . Altogether over 60,000 fungal colonies were isolated and counted during the 12-month sampling period . The prevalent fungal genera recorded were: Cladosporium, Curvularia, Fusarium, Aspergillus, Penicillium, Pithomyces, Aureobasidium, Geotrichum, Phoma, Nigrospora, Epicoccum, and Neurospora . The wet and dry seasons (indicated by the temperature, relative humidity, and rainfall data) caused seasonal periodicity in colony numbers . The influence of culture media on the isolated colonies was not significant when the total number of isolated colonies were considered on a monthly basis, but in reviewing a few of the fungal genera there were marked differences between the two media, especially with Pithomyces . Attempts were made to identify some of the isolated colonies by species, e.g., Aspergillus carneus, Aspergillus flavus, Aspergillus fumigatus, Curvularia geniculata, Fusarium oxysporum, Penicillium herquei, Pithomyces chartaum, Rhizopus arrhizus, and Syncephalastrum racemosum . Such identifications proved a basis for further studies on the role of these fungal species in the frontier problem of contamination and biodegradation of drugs and pharmaceuticals, allergies and other problems in the local environment.

Environ Health Perspect, 1975 Apr, 10, 39 - 56
Noble metals: a toxicological appraisal of potential new environmental contaminants; Brubaker PE et al.; The public health benefits expected by reducing known hazardous emissions from mobile sources should not be compromised by increasing levels of other potentially hazardous unregulated emissions . Catalytic converters are going to be used to meet the statutory requirements on carbon monoxide and hydrocarbon emissions from light duty motor vehicles . Platinum and palladium metals are the catalytic materials to be used in these emission control devices . Preliminary experimental evidence and analysis of the impact of these control devices on the future use and demand for platinum indicates that this metal may appear at detectable levels in the environment by the end of this decade . At the present time, platinum and palladium are not present in the public environment and represent potentially new environmental contaminants as a consequence of use of this new abatement control technology . There is relatively little information available to adequately assess the potential health hazards that may be associated with exposure to these metals and their compounds . Analysis of the environmental problems and concerns associated with possible new environmental contaminants are discussed . Limited estimates are made on community exposure by use of a meteorological dispersion model . Biodegradation potential and attention is also given to the limited toxicological information available.

Hoppe Seylers Z Physiol Chem, 1975 Apr, 356(4), 437 - 47
{On the role of pentachlorocyclohexene in the metabolism and action of hexachlorocyclohexane . I . Synthesis of beta-pentachlorocyclohexene and its identification as the monodehydrochlorination product of alpha-hexachlorocyclohexane (author's transl)}; Munster J et al.; It is the aim of a series of investigations to test whether or not beta-pentachloro-1-cyclohexene is an intermediate in the biodegradation of alpha-hexachlorocyclohexane . This paper describes attempts to synthesize this intermediate by chemical methods . 1) Pentachlorocyclohexene was synthesized by partial additive chlorination of chlorobenzene . Combined gas chromatography-mass spectrometry revealed that at least five different isomers of pentachlorocyclohexene had been formed . 2) Treatment of alpha-hexachlorocyclohexane with alkaline buffer (pH 8) produced trichlorobenzenes and, in small yield (4%), a pentachlorocyclohexene . This was isolated and identified as the beta-isomer by melting point (71.8 - 72.6 degrees C, uncorr.), IR- and mass spectrum . Dehydrochlorination of beta-pentachlorocyclohexene produced the trichlorobenzene isomers in a pattern which is characteristic of alpha-hexachlorocyclohexane . The position of the chlorine substituents in the beta-pentachlorocyclohexene molecule as judged from NMR studies is e-aeee . This confirms that it is the monodehydrochlorination product of alpha-hexachlorocyclohexane . The configurations of gamma- and delta-pentachlorocyclohexene, determined for comparison, are e-eeaa and e-eeee, respectively . The kinetics of dehydrochlorination of both alpha-hexachlorocyclohexane and beta-pentachlorocyclohexene in alkaline acetone/water (3 + 2) was studied by means of conductometry . Both reactions are of second order: kappa alpha-HCH 0.0495 {1 times mol- minus 1 times s- minus 1{; kappa beta-PCH 0.905 {1 times mol- minus 1 times s- minus 1} (3.6 degrees C) . 3) Dehydrochlorination of alpha-hexachlorocyclohexane in pyridine/xylene (3 + 4) was also studied . An earlier report claiming that gamma-pentachlorocyclohexene (and not the beta isomer) is produced in this medium was confirmed, if the reaction was performed at high temperature (120 - 140 degrees C) . Moreover, the ratio of trichlorobenzene isomers formed from alpha-hexachlorocyclohexane shifted to a pattern characteristic of the gamma (or gamma) isomer . However, at temperatures of 90 degrees C or less, beta-pentachlorocyclohexene was the main product . The results strongly suggest that in pyridine/xylene, the same isomer is primarily produced from alpha-hexachlorocyclohexane and is isomerized to the gamma, delta and at least two other isomers of pentachlorocyclohexene before further dehydrochlorination ensues . A simple method for the synthesis of beta-pentachlorocyclohexene is presented.

J Lipid Res, 1971 Jul, 12(4), 383 - 95
The biology of methyl ketones; Forney FW et al.; Publication Types:

Review

What Is Genome?, What Is Amino Acid?, What Is Pcr?, What Is Bioremediation?, What is Food Microbiology?, n, Microorganisms, s, Microbe, e, Bacteria, s, Bacterium, e, Bacteriology, o, Enterobacters, o, Microbial, n, Bacillus subtilis, a, Lactobacillus, r, Bacteriological, o, Escherichia coli, n, Bacteriological, r, Bacteriological, n, Escherichia coli, e, Salmonella, a, Haemophilus, r, Candida tropicalis, e, Bacillus subtilis, a, Bacteriological, i, Antibiotics, a, Streptococcal, o, Citrobacter, r, Antibiotics, o, Antimicrobial, n, Alcaligenes, s, Antimicrobials

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

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

Last modified: May 25, 2005