Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.17 (PCE)
 1,301 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Aerobic enrichment cultures from contaminated groundwaters dechlorinated trichloroethylene (TCE) (14.6 mg/liter; 111 mumol/liter) and tetrachloroethylene (PCE) (16.2 mg/liter; 98 mumol/liter) reductively within 4 days after the transition from aerobic to anaerobic conditions. The transformation products were equimolar amounts of cis-1,2-dichloroethylene and traces of 1,1-dichloroethylene. No other chlorinated product and no methane were detected. The change was accompanied by the release of sulfide, which caused a decrease in the redox potential from 0 to -150 mV. In sterile control experiments, sulfide led to the abiotic formation of traces of 1,1-dichloroethylene without cis-1,2-dichloroethylene production. The reductive dechlorination of PCE via TCE depended on these specific transition conditions after consumption of the electron acceptor oxygen or nitrate. Repeated feeding of TCE or PCE to cultures after the change to anaerobic conditions yielded no further dechlorination. Only aerobic subcultures with an air/liquid ratio of 1:4 maintained dechlorination activities; anaerobic subcultures showed no transformation. Bacteria from noncontaminated sites showed no reduction under the same conditions.
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PMID:Reductive dechlorination of Tri- and tetrachloroethylenes depends on transition from aerobic to anaerobic conditions. 189 93

Various nucleoside analogues are being used or are being considered for use as therapeutic drugs to inhibit replication of the HTLV-III/LAV virus in infected human cells. Here, the ability of seven nucleoside analogues, a combination of two analogues, and two other therapeutic compounds to induce genotoxic and cytotoxic damage in vivo was evaluated in the mouse bone marrow micronucleus test. Using a 3-consecutive-day oral treatment protocol, almost all of the test chemicals induced a significant increase in the frequency of micronucleated polychromatic erythrocytes (MN-PCE) in male B6C3F1 mice, ranked in decreasing potency as 6-thioguanine greater than Cytarabine HCl greater than 3'-azido-3'-deoxythymidine (AZT)/2',3'-dideoxycytidine combination = AZT greater than Ribavirin = 2',3'-didehydro-3'-deoxythymidine greater than 2',3'-dideoxyadenosine = 2',3'-dideoxycytidine. The frequency of MN-PCE was not increased significantly by treatment with 2',3-dideoxyinosine (DDI) or pentamidine isethionate (PI). The differential ability of AZT and DDI to induce MN in mouse bone marrow was verified from peripheral blood smears prepared from subchronic (90 day) oral studies. The lack of genotoxic activity by DDI was route-specific since, when tested by intraperitoneal injection, a small but significant increase in MN-PCE was observed. A number of these chemicals induced a significant depression in erythropoiesis. However, there was not a significant correlation between the increase in MN-PCE and the depression in the percentage of PCE. This lack of a correlation suggests that factors other than DNA damage may contribute to the inhibition in the rate of erythropoiesis. The presence of increased levels of micronuclei in bone marrow PCE following treatment with various nucleoside analogues suggests that intrinsic genotoxic activity in mammalian cells should be one factor considered during drug selection for AIDS therapy.
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PMID:Induction of micronuclei in mouse bone marrow cells: an evaluation of nucleoside analogues used in the treatment of AIDS. 191 12

Previous studies in dogs of anesthetic-epinephrine arrhythmias have used logdose or bracketed epinephrine infusion protocols to determine the arrhythmic dose of epinephrine (ADE) or plasma level of epinephrine at arrhythmias (PCE). Reported logdose ADE values for halothane preceded by thiopental induction (thiopental-halothane) are twice those with the bracket protocol. There are no reported PCE data for the bracket protocol, and neither protocol has been directly compared in the same dogs. Therefore, direct comparisons were made of thiopental-halothane ADE and PCE in seven dogs (group 1). Dogs were induced with thiopental (20 mg/kg), followed by halothane inhalation at end-tidal concentrations equivalent to MAC 1.25. Epinephrine infusion protocols were compared on two weekly test occasions, with the sequence and order of protocol testing randomized. Logdose ADE for four or more ventricular beats within 15 s was 3.92 +/- 0.60 micrograms/kg (mean +/- standard error), higher than the bracket ADE (2.54 +/- 0.34 micrograms/ml) (P less than 0.05). PCE at ADE were similar for both protocols, but six separate infusions of epinephrine were required to establish ADE with the logdose compared to four with the bracket protocol (P less than 0.05). These findings suggested enhanced epinephrine clearance with the logdose protocol. Therefore, five additional but similarly anesthetized dogs (group 2) were tested to determine if physiologic or hemodynamic conditions prior to epinephrine infusions ("initial conditions") were equivalent for both protocols. Protocols were modified to avoid provocation of ventricular arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Comparison of logdose and bracket protocols for determination of epinephrine arrhythmia thresholds in dogs anesthetized with thiopental-halothane. 1104 38

The effect of simultaneous pretreatment with vitamins C and E on the toxicity and mutagenicity of K2Cr2O7 in rats and guinea pigs was evaluated. Dietary pretreatment of Cr(VI)-intoxicated rats with ascorbic acid or alpha-tocopherol normalized vitamin C levels in lungs but not in kidneys. The synergistic preventive effect of both vitamins was confirmed in the production of lipoperoxides in Cr(VI)-intoxicated rats. Simultaneous administration of vitamins C and E in guinea pigs prevented the decrease of vitamin C levels provoked by the oxidative effects of Cr(VI). The results of the micronucleus test in bone marrow showed that it was vitamin C that caused the antimutagenic effect against bichromate, in both rats and guinea pigs. The effect of vitamin E was demonstrated only in an increase of the ratio of NCE to PCE, i.e., in a decrease of the cytotoxic but not the mutagenic effects of hexavalent chromium.
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PMID:Effect of vitamins C and E on toxicity and mutagenicity of hexavalent chromium in rat and guinea pig. 198 83

This paper describes a set of multipathway, multimedia models for estimating potential human exposure to environmental contaminants. The models link concentrations of an environmental contaminant in air, water, and soil to human exposure through inhalation, ingestion, and dermal-contact routes. The relationship between concentration of a contaminant in an environmental medium and human exposure is determined with pathway exposure factors (PEFs). A PEF is an algebraic expression that incorporates information on human physiology and lifestyle together with models of environmental partitioning and translates a concentration (i.e., mg/m3 in air, mg/liter in water, or mg/kg in soil) into a lifetime-equivalent chronic daily intake (CDI) in mg/kg-day. Human, animal, and environmental data used in calculating PEFs are presented and discussed. Generalized PEFs are derived for air----inhalation, air----ingestion, water----inhalation, water----ingestion, water----dermal uptake, soil----inhalation, soil----ingestion, and soil----dermal uptake pathways. To illustrate the application of the PEF expressions, we apply them to soil-based contamination of multiple environmental media by arsenic, tetrachloroethylene (PCE), and trinitrotoluene (TNT).
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PMID:Estimating human exposure through multiple pathways from air, water, and soil. 202 45

Studies are reviewed in which the effect of treatment/sample protocol on the induction of micronucleated polychromatic erythrocytes (MN-PCE) in male B6C3F1 mice by 3 carcinogens (benzidine, dimethylbenzanthracene and mitomycin C) were evaluated. 3 different treatment/sampling protocols were used, involving from 1 to 3 consecutive daily treatments and from 3 to 1, respectively, consecutive daily samplings beginning 24 h after the last injection. The results indicate that the 3-day injection/single sample time protocol eliminates the need for multiple sample times, minimizes the number of animals required in a study, decreases the time needed for data collection and simplifies data analysis. A comparison of the frequency of induced MN-PCE in peripheral blood and bone marrow suggests that, following a 3-injection protocol, either tissue can be used with equal efficiency.
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PMID:The induction of micronucleated polychromatic erythrocytes in mice using single and multiple treatments. 211 36

Testis weight as a percentage of body weight did not change following bilateral ligation of the efferent ducts (EDL) close to the epididymis, whereas following removal of part of the epididymis between the site of ligation and a point close to the junction between the caput and corpus (PCE), testis weight first rose linearly until Day 4 and then showed an exponential decrease between Days 4 and 28. After EDL, the perimeter of the seminiferous tubules rose for the first 7 days and then remained elevated, whereas after PCE, there was a linear decrease between Days 4 and 28. Following EDL, the percentage of altered and degenerated tubular cross-sections rose to about 30% and 10%, respectively, during the first 7 days after operation and then remained constant; after PCE, the percentage of altered tubules reached a maximum of 54% by 4 days and then fell, whereas the percentage of degenerated tubules continued to rise to 95% by 28 days. It would appear that all the effects of removal of a portion of the epididymis cannot be explained by blockage of the excurrent ducts, and a specific endocrine effect of the epididymis on the testis is proposed.
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PMID:A comparison of the effects of bilateral efferent duct ligation and of partial epididymectomy on the testes of rats. 221 89

Hydrocarbons such as TCE, PCE, TCA, gasoline and kerosene which are widely used in the industry, enter soils and groundwater from chemical waste disposal sites and from accidents. These types of substances are the most commonly encountered groundwater contaminants nationwide. Biotransformation of dissolved chlorinated hydrocarbons can provide complete mineralization to harmless end products such as CO2. It is the objective of this work to investigate the biodegradation and biotransformation, and transport of hydrocarbons in groundwater. This will be achieved first by defining and identifying relevant physical and biological processes which contribute to the fate of hydrocarbon contaminants in unsaturated/saturated soils, and providing a conceptual framework for incorporating these processes into a mathematical formulation. The conservation principles expressed in terms of quantifications of the physical, chemical and microbial processes described above lead to a system governing the phenomenon which consists of nonlinear partial differential equations. Microbial transformation conducted by both anaerobic and aerobic bacteria are considered.
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PMID:Theoretical modeling of biodegradation and biotransformation of hydrocarbons in subsurface environments. 233 35

1. Growth, food intake and abdominal fatness were measured at 7 weeks of age in male and female broilers from genetically lean and fat lines fed on isoenergetic diets containing 160, 190, 210, 230 and 260 g crude protein/kg from hatching. 2. The mean proportions of abdominal fat decreased from 39 to 20 g/kg body weight in the fat line and from 26 to 11 g/kg in the lean line over this range of protein concentrations. 3. Protein requirements, for optimum growth as a proportion of the diet did not differ between the lines but the lean line was less tolerant of inadequate dietary protein. 4. In birds fed on the same diet, conversion efficiencies of food (FCE) and dietary protein (PCE) were always superior in the lean line but energetic efficiency (EE) was similar in good growing birds of both lines. 5. When dietary protein was adequate for growth and body compositions were equalised in the two lines (by feeding higher protein diets to the fat line), lean line birds had 10% better FCE, 6% better EE and 33% better PCE. 6. It is concluded that genetic selection is a more effective and economic means of producing leaner broilers than dietary manipulation.
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PMID:Responses of body composition, growth and food efficiency to dietary protein in genetically lean and fat broilers up to seven weeks of age. 235 73

Two human carcinogens, 4-aminobiphenyl (4AB) and treosulphan (Treo), were tested in male B6C3F1 mice for the induction of micronuclei in bone marrow and peripheral blood cells by 1-, 2- and 3-exposure protocols. Both compounds tested positive. The magnitude of response with respect to the incidence of micronucleated polychromatic erythrocytes by 2- and 3-exposure protocols was considerably higher than by the single-exposure protocol. The peripheral blood results for Treo were as typically seen with a 24-h delay when compared to the bone marrow. The peripheral blood results for 4AB, however, differed from those expected. The incidence of MN-PCE in peripheral blood of animals exposed to 4AB was significantly greater than seen in the bone marrow in 2- and 3-exposure protocols. There was also an increase in the % PCE at the 60 mg/kg dose level as a function of time. Based on these studies, it is concluded that a step-wise scoring scheme may be the best protocol for rodent micronucleus assay, involving a 3-exposure protocol with single sampling of bone marrow (24 h after the last treatment) and two samplings of peripheral blood (24 h and 48 h after the first treatment). This approach is cost-effective, it limits the number of animals required and provides maximum sensitivity.
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PMID:Comparison of single-, double- or triple-exposure protocols for the rodent bone marrow/peripheral blood micronucleus assay using 4-aminobiphenyl and treosulphan. 236 81


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