摘要:

The effects of Cd on the growth of the fetal rat lung and the maturation of the pulmonary surfactant system were studied. Pregnant rats received sc infections of cadmium chloride on d 12–15 of gestation. Animals were sacrificed throughout late gestation. Fetal lungs were assayed for pulmonary surfactant lecithin and sphingomyelin. Some animals were allowed to give birth and the neonates were observed for symptoms of respiratory distress. The treatment resulted in high fetal mortality and growth retardation. Lung‐body weight ratios were reduced by 20–30% in treated fetuses. Pulmonary sphingomyelin content was not affected by the Cd treatment. Lecithin, the most important surfactant component, was reduced in absolute quantity but not in lecithin‐lung weight ratio on the last days of gestation. Parturition was delayed almost a full day by the Cd treatment, and birth weights were reduced. Of the treated neonates, 11% developed respiratory distress syndrome. All but one of these individuals died and had lungs with hyaline membranes. Prenatal exposure to Cd can (1) cause lung hypoplosia, (2) affect pulmonary surfactant, and (3) induce respiratory distress syndrome in term pups.

ISSN:0098-4108    

DOI:10.1080/15287397909529807

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The acute toxicity ofN‐nitrosodimethylamine(DMN)andN‐nitrosodiethylamine (DEN)was determined for three groups of aquatic organisms: algae, invertebrates, and fish. Toxicity of DMN and DEN to algae was assessed as a repression in the growth rate of eitherSelenastrum capricornutumorAnabaena flos‐aquaein static bioassay tests. DMN and DEN concentrations of 1–10 ppm depressed algal growth in all cases. Invertebrate toxicity was determined in 96‐h static bioassay tests withDugesia dorotocephalaandGammarus limnaeus.The data indicated that these organisms are not highly susceptible to nitrosamine toxicity. The 96‐h LC50s forD. dorotocephalawere 1365 and 1490 ppm for DMN and DEN, respectively. Similar studies withG. limnaeusindicated LC50s of 330 and 500 ppm for DMN and DEN, respectively. Fish toxicity was also determined in 96‐h static bioassays with the fathead minnow(Pimephales promelas).Acute toxicities were calculated as LC50s of 940 and 775 ppm for DMN and DEN, respectively. Algae were quite sensitive to relatively low levels of volatile nitrosamines, but higher organisms(invertebrates and fish)were relatively insensitive.

ISSN:0098-4108    

DOI:10.1080/15287397909529808

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Cd was measured in the feces, urine, blood, and hair of U.S. inhabitants without known high Cd exposure in Chicago, Illinois, and Dallas, Texas, and in autopsy tissues of accident victims in Dallas. The average intake of Cd In food was estimated to be 13–16 μg/d and was higher for males than females. The average levels of Cd were 0.59–0.77 μg/l in urine, 0.09–0.11 μg per 100 ml in blood, 0.83–1.10 μg/g in hair, 21 μg/g in kidney cortex, 1.2 μg/g in liver, 0.067 μg/g in muscle, 0.58 μg/g in pancreas, and 0.040 μg/g in fat. Hair Cd was higher for males than females. Cd levels increased with age in urine and all tissues and were higher in cigarette smokers than nonsmokers in urine, blood, and all tissues.

ISSN:0098-4108    

DOI:10.1080/15287397909529809

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Lead acetate in milk was fed daily to infant rhesus monkeys at doses averaging 0 (control), 0.287 (low‐Pb), or 0.880 (high‐Pb) mg/kg. for the first year of life. Pb concentrations in whole blood (PbB) averaged 4.15, 31.71, and 65.17 μg/dl for the control, low‐Pb, and high‐Pb groups, respectively, during the year of treatment and declined toward control levels when Pb dosing was stopped. Behavioral observations during the year of treatment had shown that both experimental groups were retarded in their acquisition of object‐cue discrimination reversal learning sets. At 4 yr of age, when PbB levels in all animals were normal, the ability of the same monkeys to acquire a series of 3 spatial‐cue reversal learning sets was examined; these data form the basis for this report. In the first problem, the high‐Pb group was significantly retarded in acquisition of the original discrimination and of most reversals, and the low‐Pb group was retarded on reversal 1 only. These deficits declined in severity across the three problems administered, in a manner similar to that seen in the tests given during the first year of life. These data demonstrate that reversal learning retardation, observed early in life, can recur in postadolescent primates with a history of chronic, low‐level Pb intoxication during infancy.

ISSN:0098-4108    

DOI:10.1080/15287397909529810

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Four groups of 4 domestic pigs were exposed to 0, 20, 100, and 500 ppm benzene vapor 6 h/d, 5 d/wk, for 3 wk. Two groups of 10 rats were exposed to 0 and 500 ppm: the exposed rats for 6 h/d, 5 d/wk, for 3 wk, the nonexposed rats for 6 h/d, 5 d. Rats were killed within 72 h after exposure; values for pigs were obtained shortly after exposure and on final examination at 4–16 wk after exposure.

ISSN:0098-4108    

DOI:10.1080/15287397909529811

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

To determine mortality caused by inhaled sulfuric acid mist, groups of Hartley guinea pigs 2–3 mo old were exposed for 8 h to graded concentrations of aerosols of 0.4 or 0.8 μm mass median aerodynamic diameter. Relative humidity during exposures was maintained at 70–80%. Based on probit analysis, the concentration required to produce 50% mortality (LC50) for deaths to 21 d after exposure was 30 mg/m3for the 0.8‐μm aerosol. For the 0.4‐μm aerosol, the LC50 was above 109 mg/m3, the highest concentration obtainable at that particle size. At both particle sizes, the animals either tended to develop severe dyspnea and die minutes (0.4 μm) or hours (0.8 μm) thereafter or appeared nearly unaffected. Lesions in animals that died as a result of 0.4‐μm exposures were restricted to hyperinflation; animals that died as a result of 0.8‐μm exposures also showed hemorrhage and transudation. No gross or histopathologic changes were observed in animals that appeared unaffected during exposure. Differences in total and/or regional respiratory tract deposition may account for the different responses to the two aerosols.

ISSN:0098-4108    

DOI:10.1080/15287397909529812

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

To determine whether vitamin E(dl‐α‐tocopherol ) supplementation of the diet provides protection from inhaled oxidants such as ozone (O3) in community air pollution, its effects were studied in healthy adult volunteers. Experimental groups received 800 or 1600 IU of vitamin E for 9 wk or more; control groups received placebos. Double‐blind conditions were maintained throughout the study. Biochemical parameters studied included red blood cell fragility; hematocrit and hemoglobin values; red cell glutathione concentration; and the enzymes acetylcholinesterase, glucose‐6‐phosphate dehydrogenase, and lactic acid dehydrogenase. No significant differences between the responses of the supplemented and placebo groups to a controlled O3exposure (0.5 ppm for 2 h) were found for any of these parameters. The results indicate that vitamin E supplementation in humans, at the levels employed in this experiment, gives no added protection against blood biochemical effects of O3in intermittently exercising subjects under exposure conditions simulating summer ambient air pollution episodes.

ISSN:0098-4108    

DOI:10.1080/15287397909529813

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Pregnant rats were injected with vehicle or 1.2 μg diethylstilbestrol (DES)during wk 2 or 3 of gestation; their female offspring(∼ 50 d old)were fed 7,12‐dimethyl‐benz[a]anthracene(DMBA).The survivors(27 per group) were sacrificed 30 wk later. The three groups did not differ in the number of tumor‐bearing animals; however, significantly more palpable mammary tumors arose in both DES‐exposed groups than in controls. When DES was given during the second trimester, palpable tumors appeared earlier than in the other two groups. Thus, transplacental exposure to DES potentiated the action of a known carcinogen (DMBA) on rat mammary tissue. These results raise the possibility that, for young women, DES exposurein uteromay have affected tissues other than the vagina. Further investigation is warranted, with special emphasis on the effects of DES on mammary and other estrogen‐sensitive tissues.

ISSN:0098-4108    

DOI:10.1080/15287397909529814

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Mice and dogs were treated iv with the cytostatic proteins abrin and ricin and observed for clinical, biochemical, and morphological aberrations. In both mice and dogs death occurred within a narrow dose range. Dogs given toxic doses of ricin and abrin showed weakness, anorexia, apathy, and moderate fever. No signs attributable to the central nervous system were observed. Dogs dying from intoxication expired after 15–40 h. After nonlethal doses the animals recovered, apparently completely, in 1–3 wk. No delayed changes were observed in dogs after 4 mo.

ISSN:0098-4108    

DOI:10.1080/15287397909529815

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Polybrominated biphenyls (PBBs) have produced a variety of effects including alterations in the endocrine system and in the activity of microsomal mixed‐function oxidases (MFOs). Because steroid hormones are substrates for MFOs, effects of PBBs on the endocrine system may be a consequence of enhanced steroid hormone catabolism. Therefore, as a first step in evaluating the effect of PBBs on steroid hormone metabolism, it was of interest to determine effects of perinatal exposure to PBBs on the response to exogenously administered steroid hormones. Rats were exposed to 0, 10, or 100 ppm PBBs from d 8 of gestation until d 28 postpartum, when experiments were conducted. Responses to labeled steroid hormones were generally modified in a manner directly related to PBB dose and were correlated with changes in serum and target tissue radioactivity. Stimulated metabolism of steroid hormones may account; at least in part, for endocrine‐related alterations produced by PBBs. Although the potential for decreased reproductive capacity following PBBs cannot yet be accurately predicted, these experiments suggest that fertility may be reduced following PBBs as a consequence of accelerated steroid hormone metabolism and/or excretion.

ISSN:0098-4108    

DOI:10.1080/15287397909529816

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor