摘要:

Cadmium represents a major aquatic pollutant in many parts of the world. Yet, despite the fact that cadmium accumulates in high concentrations in fish tissues, is found in polluted aquatic environments, and is carcinogenic and immunotoxic in a variety of mammalian species, the effects of cadmium on the immune responses of directly exposed aquatic species have not been clearly defined. This study was designed to assess the effects of in vivo cadmium exposure, at a concentration found in contaminated aquatic environments, on the immune defense mechanisms of fish. In this study, no effects were observed upon body weight, lysozyme activity, or cell viability, despite the high concentration of accumulated cadmium in the gills and liver. Furthermore, in the absence of any clinical manifestations or overt toxicity, exposure of rainbow trout to waterborne cadmium at 2 ppb altered macrophage‐mediated immune functions, including phagocytosis and free radical production, in a time‐dependent manner. Similar immunotoxic effects of cadmium have also been observed in mammals. Although interspecies comparisons between mammalian and fish immune responses are extremely complicated and need to be approached with caution, results from this study suggest the applicability of fish as an additional/alternative animal model for immunotoxicological studies.

ISSN:0098-4108    

DOI:10.1080/15287399509531993

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effect of cadmium (Cd) in drinking water on repair of bone at a site of hole injury to the tibia of young rats was followed using quantitative methods. The rats (3–4 wk old) were given 20 ppm and 200 ppm Cd for 5 wk and compared to a control group. A slight reduction (about 10%) in body weight and water and food consumption was observed in cadmium‐exposed rats as compared to control rats. Clinical chemistry tests in the blood and histology of kidney, liver, and bone did not indicate changes related to Cd toxicity. A significant reduction (43%) in alkaline phosphatase (ALP) and tartarate‐resistant acid phosphatase (TRAP) (46%) enzymatic activity was observed at 4 and 7 d postinjury respectively, in the site of injury in the rats receiving 200 ppm Cd in drinking water as compared to control rats. Calcium accumulation in the newly formed repair tissue at the site of injury was also significantly reduced (53%) at 13 d postinjury in the Cd‐treated (200 ppm) rats as compared to control rats. It is concluded that Cd probably exhibits an effect on the bone repair process as reflected by reduction in ALP activity (osteoblastic cells) and mineralization at the site of injury in the tibia of young rats.

ISSN:0098-4108    

DOI:10.1080/15287399509531994

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The ability of monoisoamylmeso‐2,3‐dimercaptosuccinate (Mi‐ADMS) to offset the characteristic organ pathology of intraperitoneally administered cadmium chloride (CdCl2) and that of the cadmium‐cysteine complex has been examined in male Wistar rats. The tissues examined for damage were the testes, kidney, liver, pancreas, and bone marrow. At a high dose of CdCl2(0.03 mmol/kg, ip) testicular damage was completely prevented by Mi‐ADMS (0.50 mmol/kg, ip) given immediately. A decrease in the protective ability of the antagonist was observed following delayed administration of Mi‐ADMS given at 1, 2, 4, and 24 h post CdCl2. At a lower dose of CdCl2(0.006 mmol/kg, ip), Mi‐ADMS furnished essentially full protection from testicular damage when given (0.50 mmol/kg, sc) at 0 and 1 h after CdCl2. The administration of cadmium‐cysteine complex (0.01 mmol/kg, ip) induced notable renal tubular damage, which was antagonized by the administration of Mi‐ADMS (0.50 mmol/kg, ip) as late as 4 h after the complex. At a 24‐h delay, extensive tubular necrosis was found on sacrifice after 4 d. The administration of cadmium‐cysteine complex ip reduced, but did not eliminate, the characteristic damage of the seminiferous tubules found for cadmium alone. There is a progressive reduction of testicular weight as the interval between cadmium and antagonist administration increases. The average kidney weights of the animals given CdCl2‐cysteine complex were increased in comparison to normal controls. The antagonistic effects of Mi‐ADMS treatment on cadmium intoxication in the kidneys and the testes of rats is very similar to that found for effective dithiocarbamate antagonists. In order to obtain complete protection of the testes from the deteterious effects of cadmium, such antagonists must be administered no later than about 1 h after the cadmium.

ISSN:0098-4108    

DOI:10.1080/15287399509531995

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The objective of this study was to investigate the in vitro dermal absorption of [14C]dimethylarsinic acid. This organic arsenical is used as a herbicide and is a product of the mammalian metabolism of inorganic arsenic. Discs of preclipped dorsal skin were cut from adult female B6C3F, mice and mounted in flow‐through diffusion cells. HEPES‐buffered Hanks balanced salt solution was used as receptor fluid. Doses of dimethylarsinic acid included 10, 100, and 500 μg and were applied onto the skin (0.64 cm2). Experiments (24 h) were conducted using solid compound and aqueous solution (20, 100, and 250 μl) and soil (23 mg/cm2) as vehicles. The epidermal surface was washed at 24 h to remove compound that did not penetrate. The wash contained the greatest percentage of the dose in all experiments. Absorption of the compound into the skin and receptor fluid was observed and ranged from <1 to 40% of the dose in experiments with the three exposure scenarios. The rank order of the various exposure conditions of dimethylarsinic acid absorption (10 μg) into the skin and receptor fluid was 20 μl water > 100 μl water > solid > 250 μl water > soil. No dose or pH effects on absorption of dimethylarsinic acid was observed. There was also no pH effect on the partitioning of dimethylarsinic acid between 1‐octanol and buffer. Short‐term (1 h) exposure of dimethylarsinic acid in water followed by wash of the skin resulted in <1 % of the dose being absorbed. Thus, vehicles and duration of exposure have important roles on the in vitro dermal absorption of dimethylarsinic acid in mouse skin.

ISSN:0098-4108    

DOI:10.1080/15287399509531996

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Acrylic acid (AA) is used in large amounts to produce acrylic esters and polymers. Here we report on the disposition and metabolism of [1‐14C]AA in male C3H mice and Fischer 344 (F344) rats after oral (40 and 150) mg/kg) or cutaneous (10 and 40 mg/kg) administration. Although these and other strains of rodents have been used frequently in toxicity studies of AA, results of pharmacokinetic studies are available for only the Sprague‐Dawley rat. In the current study, C3H mice rapidly absorbed and metabolized orally administered AA, with about 80% of the dose exhaled as14CO2within 24 h. Excretion in urine and feces accounted for approximately 3 % and 1 % of the dose, respectively. Elimination of14C from plasma, liver, and kidney was rapid but was slower from fat. The disposition of orally administered AA in F344 rats was similar to the results obtained from mice. After cutaneous administration to C3H mice, about 12% of the dose was absorbed, while the remainder apparently evaporated. Approximately 80% of the absorbed fraction of the dose was metabolized to14CO3within 24 h. Excretion in urine and feces each accounted for less than 0.5% of the dose. Elimination of radioactivity from plasma, liver, and kidney was rapid; however, levels in fat were higher at 72 h than at 1 or 8 h. After cutaneous administration to F344 rats, 19–26% of the dose was absorbed, and the rest apparently evaporated. Disposition of the absorbed fraction of the dose was similar to results found in mice. Results from an in vitro experiment with rat skin showed that at least 60% of the applied dose evaporated and about 25% was absorbed, confirming the in vivo results. High‐performance liquid chromatography (HPLC) analysis of rat urine and rat and mouse tissues indicated that absorbed AA was rapidly metabolized by the β‐oxidation pathway of propionate catabolism. In summary, rapid detoxification of systemically absorbed AA, as observed here in C3H mice and F344 rats, can explain findings that AA causes minimal systemic toxicity despite its causing irritation at portal‐of‐entry tissues.

ISSN:0098-4108    

DOI:10.1080/15287399509531997

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Studies were initiated to ascertain whether body hair could be used to develop a biological marker for chronic exposure to industrial neurotoxicants that yield the metabolite 2,5‐hexa‐nedione (2,5‐HD), that is,n‐hexane and methyln‐butyl ketone. Rats were injected daily with a 50 mg/kg ip dose of 2,5‐HD for 45 d. At intervals, body hair and individual vibrissae were removed (under general anesthesia) and tested for the presence of pyrrole substances withp‐N,N‐dimethylaminobenzaldehyde (DMAB, Ehrlich's reagent). Vibrissae and body hair were stained a reddish color that was distinctly different from that observed with the hair taken from control animals. Solubilized body hair protein from the treated animals gave a positive Ehrlich's test, while that from control animals was negative. Spectral analysis of the DMAB‐treated hair from experimental animals disclosed a maximum absorbance at 530 nm, which indicated the presence of pyrrole substituents. Serial analysis of individual nose hairs taken during 2,5‐HD administration showed a progression with time of the region staining positively for pyrroles, thus indicating that the process can proceed in growing hair. These findings suggest the potential utility of hair as an indicator for chronic exposure to this class of industrial chemicals possessing neurotoxicity potential. This could complement urinary analysis, which is now used to confirm recent exposure.

ISSN:0098-4108    

DOI:10.1080/15287399509531998

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The inhibition and aging of acetylcholinesterase (AChE) in fingerling channel catfish(Ictalurus punctatus)brain tissue was studied after single in vivo exposures to high levels of chlorpyrifos (0.25 mg/L), chlorpyrifos‐oxon (7 μg/L), parathion (2.5 mg/L), or paraoxon (30 μg/L). Exposure to both parent compounds produced identical initial inhibition (95%), but in the later sampling times there was significantly more inhibited AChE in the chlorpyrifos‐treated fish than in the parathion‐treated fish (47% and 28%, respectively, on d 16). There were higher levels of aged AChE following chlorpyrifos exposure than following parathion exposure, but differences were not significant. Exposure to both oxons produced initial inhibition greater than 90%, and patterns of recovery and aging were statistically similar between both compounds; no significant inhibition was observed after d 11. The similar patterns of inhibition, recovery, and aging between the two oxon treatments, which have similar lipophilicities, suggest that the greater amount of AChE inhibition and aging observed in the chlorpyrifos‐treated fish compared with the parathion‐treated fish probably results from the higher lipophilicity of chlorpyrifos than of parathion. Overall, the prolonged brain AChE inhibition exhibited in catfish exposed to phosphorothionates is not the result of aging of the inhibited enzyme but is the result of either a slow rate or a lack of spontaneous reactivation.

ISSN:0098-4108    

DOI:10.1080/15287399509531999

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In this article, the relationship was studied between the in vivo mutagenicity assay of mouse bone marrow micronucleus (MIC), and four in vitro assays:Salmonella typhimurium, chromosomal aberrations in Chinese hamster ovary (CHO) cells, sister chromatid exchanges (SCE) in CHO cells, and mutation in mouse lymphoma L5178Y cells. A comparison with the rodent carcinogenicity data was also undertaken. The MIC data on 49 chemicals were generated by Shelby et al. (1993). The MIC assay system employed three daily exposures by intraperitoneal injection; bone marrow samples were obtained 24 h following the final exposure. A preliminary analysis indicated that the 49 chemicals selected by Shelby et al. (1993) are a representative subset of the National Toxicology Program database. This study showed that MIC has a number of particular characteristics that are not shared by other biological systems. MIC is basically different from rodent carcinogenicity, despite being an in vivo system. At the same time, it responds to the chemicals in a different way from that of the in vitro genotoxicity assays. These in vitro assays mainly differ from each other in their different sensitivities to the genotoxins: MIC gives just a few positives (limited sensitivity), but, at the same time, some of these positives are detected only by the most sensitive assays, like the mouse lymphoma or SCE assays. In terms of risk assessment, MIC does not complementSalmonellafor predicting chemical carcinogenicity, and would be better used to verify if the in vitro positive chemicals are able to exert their genotoxic potential in vivo.

ISSN:0098-4108    

DOI:10.1080/15287399509532000

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This study was designed to examine the fibrogenic potentials of four coal slags that are being used as substitutes for silica sand in abrasive blasting. Six groups of 100 male Sprague‐Dawley rats, including four coal slag groups, a vehicle control, and a positive control for fibrosis (Minusil quartz), were used. Each dust treatment group was given a single 40‐mg dose of test agent via intratracheal instillation. Interim sacrifices of 15 animals per group were performed at 2 d, 3 mo, and 6 mo posltreatment, with the terminal sacrifice conducted at 12 mo. Hematoxylin and eosin stained histologic sections were prepared from designated formalin‐fixed tissues collected at each necropsy and examined microscopically. Pulmonary silicon analyses were performed for each group at the 2‐d and 12‐mo sacrifices. Pulmonary function analyses were conducted for each group at the 3‐, 6‐, and 12‐mo sacrifices. Lung hydroxyproline analyses were conducted for 15 animals in each group at the terminal sacrifice. The pulmonary fibrogenic potentials of the four coal slag groups were compared histologically with the Minusil and vehicle controls. A mild to moderate interstitial fibrosis, which was progressive with time, was noted in each of the coal slag groups. However, the coal slag‐induced lung fibrosis was much less than that produced by Minusil. Differences in fibrosis among the individual coal slags were relatively minor and certainly not as striking as those between the slags and Minusil. Other data derived from this study, such as lung hydroxyproline content, pulmonary particulate burdens, pulmonary function, and animal body weights, provided further evidence of a reduced toxicity for the coal slags compared to Minusil.

ISSN:0098-4108    

DOI:10.1080/15287399509532001

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0098-4108    

DOI:10.1080/15287399509531992

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor