摘要:

Using multiple m easurem ents from serum collected over 10 yr (1982, 1987, and 1992), we estimated the half-life of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in 213 veterans of Operation Ranch Hand, the Air Force unit responsible for the aerial spraying of Agent Orange in Vietnam. The potential influences of age, percent body fat, and changes in percent body fat on the half-life estimate were also examined. The mean decay rate of TCDD for these veterans is 0.0797 per year with 95% confidence interval 0.0727 to 0.0868 per year; the corresponding half-life estimate is 8.7 yr with 95% confidence interval 8.0-9.5 yr. Half-life increased significantly with increasing body fat, but not with age or relative changes in percent body fat.

ISSN:0098-4108    

DOI:10.1080/009841096161744

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

In this survey, lipid metabolism and activities of the lipolytic enzymes diglyceride lipase (DLase) and phospholipase A (PLase A) in the oyster digestive glands (ODGs), with 4% added acetic acid (the same acid concentration as vinegar) and incubated at 37 C for 3 h, were investigated. Significant decreases in triglyceride, phosphatidylcholine, and phosphatidylethanolam ine and increases in monoglyceride, lysophosphatidylcholine, and lysophosphatidylethanolamine were observed in the acetic acid-treated ODGs. Changes in ODGs treated with PBS were smaller than in the acetic acid-treated ones but larger than in the nontreated ones. Both PLase A1 and PLase A2 in ODGs were activated by addition of acetic acid and incubated at 37 C for 3 h. PLase A1 activities were higher than those of PLase A2 in all experim ental O DGs. Addition of formic acid also induced activation of PLase A at pH 2. On the other hand, DLase in O DGs decreased rem arkably with acetic acid treatment. These data showed that the increase in lipid metabolites such as free fatty acids and lysophospholipids in the acetic acid-treated ODGs might be due to catabolism of PLase A, which was activated by the acid treatm ent at 37 C.

ISSN:0098-4108    

DOI:10.1080/009841096161753

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

Trichloroacetonitrile (TCAN) is a by-product of the chlorine disinfection of water containing natural organic material. When administered by gavage to pregnant Long-Evans rats in a medium-chain triglyceride vehicle, tricaprylin oil (Tricap), at a volume of 10 m l/kg, TCAN induced fetal cardiovascular anom alies at doses as low as 1 m g/kg/d (Smith et al., 1988). A slight but possibly biologically significant increase over the water control group in adverse pregnancy outcomes (resorptions, reduced fetal weight, and anomalies) was observed in the Tricap control group. This led us to reexamine the developmental effects of TCAN in a second vehicle, corn oil (CO). Five groups of approximately 20 pregnant female rats received TCAN in CO at 15, 35, 55, and 75 mg/kg/d, and in Tricap at 15 m g/kg/d (10 m l/kg dosing volume). Corn oil, Tricap, and water served as vehicle controls. Animals were treated by oral intubation on gestation d 6- 18 (vaginal plug=d0). Five out of 20 dams (75 m g/kg) died during treatment. Adjusted maternal weight gain was lower in females receiving 35 mg/kg TCAN or greater. The mean percent of nonlive implants per litter was elevated at 55 and 75 m g/kg TCAN (CO). The TCAN dose-response curve for fetal (but not maternal) effects was shifted to the right when CO was compared to Tricap. Fetal weight was reduced at 15 m g/kg TCAN (Tricap) and at 55 m g/kg TCAN (CO). When TCAN was adm inistered in CO, the mean frequency of soft-tissue malformations decreased with significantly fewer septal and great vessel cardiovascular defects observed. We hypothesize that the volatile haloacetonitrile, TCAN, may interact with the Tricap vehicle in such a way that effects on the developing cardiovascular system are potentiated. The lowest observed adverse effect level for TCAN (CO) was determined to be 35 kg/kg.

ISSN:0098-4108    

DOI:10.1080/009841096161762

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

Sarin (Agent GB, isopropyl methylphosphonofluoridate) is an organophosphate cholinesterase inhibitor. Sarin (Type I or Type II) was administered by gavage to CD rats on d 6-15 of gestation at dose levels of 0, 100, 240, or 380 mu g/kg/d and to New Zealand White (NZW) rabbits on d 6-19 of gestation at dose levels of 0, 5, 10, or 15 mu g/kg/d. Females were weighed on gestational days (GD) 0, 6-16 for rats and 6-20 for rabbits, and immediately prior to termination (GD 20 for rats and GD 29 for rabbits). All animals were monitored daily for clinical signs of toxicity throughout dosing and until sacrifice. At necropsy, gravid uteri were weighed and examined for the number and status of implants (live, resorbed, or dead). Individual fetal body weight, malformations, and variations (external, visceral, and skeletal) were recorded. Rat and rabbit dams in the high-dose groups exhibited significant signs of maternal toxicity and increased maternal mortality. Examination of gravid uteri revealed no statistical differences among treatment groups in the incidence of resorptions or of dead or malformed fetuses, or in average body weight of live fetuses per litter. These results show no evidence of developmental toxicity in the CD rat or NZW rabbit following exposure to either Type I or Type II sarin during embryonic differentiation and major organogenesis, even at a dose that produced maternal toxicity.

ISSN:0098-4108    

DOI:10.1080/009841096161771

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

The toxic effects of cadmium, mercury, and copper were compared over the range 0.01, 0.03, and 0.1 m M using the isolated perfused rat liver preparation. All metals caused similar changes in various parameters used to describe general toxicity. Thus reductions in oxygen consumption, perfusion flow, and biliary secretion were found, while lactate dehydrogenase release into the perfusate, as well as liver weight, increased also in a dose-dependent fashion. Each metal caused similar magnitudes of changes and exerted sim ilar potency. Measurement of other parameters indicating more specific injury revealed a number of differences. Although all metals reduced hepatic ATP concentration, mercury and cadmium were more potent than copper in this respect. Cadmium was the most potent at decreasing reduced glutathione levels. Mercury was most effective at increasing tissue calcium content, while copper was less so, and cadmium ineffective. Only copper significantly increased tissue malondialdehyde (MDA) content, while all metals increased its release into perfusate. Furthermore, whereas cadmium seemed the most potent metal in increasing MDA release, it was least efficacious, while copper was the most. Antioxidants such as superoxide dismutase, catalase, and Trolox C only reduced cadmium's influence on MDA in perfusate; however, they did not affect cadmium's ability to alter most other parameters of vitality. Albumin reversed the toxic effects of copper and mercury, but not cadmium. While metal-induced reductions in perfusion flow accounted for some of the toxic effects of the metals investigated, the results as a whole supported the suggestion that all metals exerted toxicity at the mitochondria, since ATP levels were reduced in a manner that could not be reproduced by perfusion flow reduction alone. Lipid peroxidation appears to play little role in determining toxicity induced by any of these metals. Furthermore, albumin may play an important physiological role in preventing hepatic injury that might otherwise be induced through acute metal intoxication.

ISSN:0098-4108    

DOI:10.1080/009841096161780

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

A model using semidom esticated mink was set up to study the effects of chronic oral methylmercury exposure in piscivorous mammals. Three groups of mink were fed daily with diets containing approximately 0.1, 0.5, and 0.9 mu g/g of total mercury. Piscivorous and nonpiscivorous fish, naturally contaminated with methylmercury, were used to prepare diets. Renal injury was evaluated using total urine protein/creatinine ratio and differentiation of urinary low-molecular-weight and high-molecular-weight proteins on sodium dodecyl sulfate polyacrylam ide gel electrophoresis (SDS-PAGE). The significance of the total urine protein/ creatinine ratio data was assessed by comparing the results to a 95% group-based reference interval. The values for total urine protein/creatinine ratio did not reveal any significant increased excretion, and no dose-related trends were observed within the reference interval. Overall the total urine protein data did not suggest renal damage. Analysis of the SDS-PAGE electrophoretograms did not suggest the presence of any persistent glomerular damage in any group. High-molecular-weight proteins were not detected more frequently for any of the dose groups. During the adaptation phase, the B2M-like protein band was not remarked during the visual analysis of the gels. The B2M-like protein band was remarked during the gel analysis only several weeks into the exposure phase. This B2M-like protein band was more prevalent in urine samples taken from minks in the 0.5 and 0.9 mu g/g groups than in the 0.1 mu g/g group. These latter data, however, did not allow an evaluation of a quantitative dose-response excretion with time. The B2M-like data are suggestive of very minor renal injury.

ISSN:0098-4108    

DOI:10.1080/009841096161799

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor

摘要:

The microbiocidal activity of glutaraldehyde was inactivated by reaction with sodium bisulfite via formation of a proposed glutaraldehyde-bisulfite complex. High-performance liquid chromatography (HPLC) analysis of 2% (0.2 M) alkaline glutaraldehyde indicated complete loss of glutaraldehyde at a 2.2:1 molar ratio of sodium bisulfite to glutaraldehyde. Neither 1.7% (0.17 M) sodium bisulfite alone nor the glutaraldehyde-bisulfite complex was microbiocidal when tested against Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, and Polybac Polyseed BOD seed inoculum. Bacterial inhibition tests indicated that the glutaraldehyde-sodium bisulfite complex had no effect on the growth of sewage microorganisms at concentrations as high as 50-100 ppm (5 10-4-1 10-3M), with an IC50 of 230-440 ppm (2.3 10-3-4.4 10-3 M), based on glutaraldehyde concentration. A28-d closed bottle test showed a 5-d biodegradation of 48% and 51%, and a 15-d biodegradation of 57% and 63% for 3:1 and 2.2:1 bisulfite to glutaraldehyde molar ratios, respectively. Acute aquatic toxicity testing with Daphnia magna demonstrated an LC50 of 41-109 ppm (4.1 10-4-10.9 10-4 M) and a no-observed-effect concentration (NOEC) of 16 ppm (1.6 10-4M) for the proposed glutaraldehyde-bisulfite complex (based on glutaraldehyde concentration), approximately 10-fold higher than found for glutaraldehyde alone, indicating that the proposed glutaraldehyde-bisulfite complex is less toxic to the environment than glutaraldehyde.

ISSN:0098-4108    

DOI:10.1080/009841096161807

出版商:Informa UK Ltd    

年代:1996

数据来源: Taylor