摘要:

There has been much debate concerning the teratogenic potential of the organophosphate pesticides, including malathion, although few experimental studies have been performed on mammals. This study was designed to expand the range of animal species used in the testing of malathion and to further evaluate malathion's teratogenic potential. A 100‐mg/kg dose regimen from d 7 to d 12 of gestation was administered to New Zealand white rabbits. This produced no detectable differences in the number of resorptions, fetal size, and external or visceral anomalies between the treated and control groups. This suggests, as has been previously reported, that malathion has little or no teratogenic potential in the mammal.

ISSN:0098-4108    

DOI:10.1080/15287398909531251

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The effect of the diuretic drug furosemide on two‐stage urinary bladder carcinogene‐sis in F344 rats initiated byN‐butyl‐N‐(4‐hydroxybutyl)nitrosamine (BBN) was investigated with regard to possible promoting activity. BBN was administered at 2 doses, 0.01 or 0.05%, in drinking water for 4 wk, and thereafter furosemide was given by gavage 3 times weekly for 32 wk, 250 mg/kg body weight. Furosemide ingestion induced diuresis with an alkaline, hypotonic urine. No significant difference with regard to incidences of bladder lesions were apparent between furosemide and control groups. The present investigation indicated that neither furosemide nor its related polyuria acted as a promoter in two‐stage urinary bladder carcinogenesis.

ISSN:0098-4108    

DOI:10.1080/15287398909531252

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Tetralin, a component of fuels, solvents, and varnishes, is metabolized in male Fischer 344 rats to 1‐tetralol, 2‐tetralol, 2‐hydroxyl‐1‐tetralone, 4‐hydroxyl‐1‐tetralone, 1,2‐tetralindiol, and 1,4‐tetralindiol. Rats treated with tetralin demonstrated the classic lesions of hydrocarbon‐induced nephropathy.

ISSN:0098-4108    

DOI:10.1080/15287398909531253

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Effects of endogenously produced and exogenously added benzene metabolites on the nuclear DNA synthetic activity were investigated using a culture system of mouse bone marrow cells. Effects of the metabolites were evaluated by a 30‐min incorporation of [3H]thymidine into DNA following a 30‐min interaction with the cells in McCoy's 5a medium with 10% fetal calf serum. Phenol and muconic acid did not inhibit nuclear DNA synthesis. However, catechol, 1,2,4‐benzenetriol, hydroquinone, andp‐benzoquinone were able to inhibit 52, 64, 79, and 98% of the nuclear DNA synthetic activity, respectively, at 24 μM. In a cell‐free DNA synthetic system, catechol and hydroquinone did not inhibit the incorporation of [3H]thymidine triphosphate into DNA up to 24 μMbut 1,2,4‐benzenetriol and p‐benzoquinone did. The effect of the latter two benzene metabolites was completely blocked in the presence of 1,4‐dithiothreitol (1 mM) in the cell‐free assay system. Furthermore, when DNA polymerase a, which requires a sulfhydryl (SH) group as an active site, was replaced by DNA polymerase I, which does not require an SH group for its catalytic activity, p‐benzoquinone and 1,2,4‐benzenetriol were unable to inhibit DNA synthesis. Thus, the data imply thatp‐benzoquinone and 1,2,4‐benzenetriol inhibited DNA polymerase a, consequently resulting in inhibition of DNA synthesis in both cellular and cell‐free DNA synthetic systems. The present study identifies catechol, hydroquinone, p‐benzoquinone, and 1,2,4‐benzenetriol as toxic benzene metabolites in bone marrow cells and also suggests that their inhibitory action on DNA synthesis is mediated by mechanism(s) other than that involving DNA damage as a primary cause.

ISSN:0098-4108    

DOI:10.1080/15287398909531254

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The effect of chronic exposure to micromolar concentrations of Aroclor 1254 (Aro) on the hepatic lipid metabolism was studied in long‐term cultures of adult rat hepato‐cytes. Hepatocytes were cocultivated with mytomicin C‐treated 3T3 cells and exposed for 2 wk to Aroclor 1254 concentrations ranging from 0.01 to 20 μg/ml. The Aro‐exposed cultures showed intracytoplasmic lipid droplets and a maximum increase of 55% in the triglyceride (TG) content and of 4.4‐fold in the cytochrome P‐450 content. Labeling studies with [14C]acetic and [14C]oleic acid showed no changes in the uptake of fatty acid and TG precursors by the Aro‐treated cultures; the synthesis of cellular lipids from [14C]acetic acid was slightly inhibited by Aroclor 1254, but that from (14C]ol‐eic acid was increased, specially for TG (37%). The secretion of total lipids and TG was 2.1‐ and 2.7‐fold lower, respectively, in the cultures treated with 20 μg/ml of Aroclor 1254, resulting in an increase of 1.9‐fold in the intracellular content of TG. The synthesis of cellular proteins labeled with [3H]leucine was unchanged in the Aro‐treated cultures, but the secretion of exportable proteins was 1.7‐fold lower in the cultures treated with 20 μg/ml of Aroclor 1254. Our results showed that long‐term exposure to in vivo relevant concentrations of Aroclor 1254 produced morphological and biochemical changes in cultured hepatocytes, like those described in vivo, and intracellular TG accumulation due mostly to impaired secretion of TC by the hepatocytes. Our results also suggest that this culture system could be useful for the screening of toxic agents producing fatty liver and the study of the involved mechanism(s).

ISSN:0098-4108    

DOI:10.1080/15287398909531255

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

1‐Nitropyrene (NP), as found in the environment, is more typically associated with carbonaceous particles than found as an aerosol of the pure compound. To determine whether (and why) an association with particles resulted in prolonged lung retention of NP, rats were exposed to14C‐NP as a pure aerosol or adsorbed on carbon black particles. Total14C retained in the lung was greater at all times from 0.5 h to 30 d after exposure to14C‐NP adsorbed to carbon black particles than after exposure to pure14C‐NP (p< .05). The fraction of total14C in lung bound to carbon black particles decreased steadily with time after exposure, indicating in vivo removal of NP from the particles. At 0.5 h after exposure, the fraction of the estimated deposited14C that was covalently bound to lung macromolecules was twofold greater for NP adsorbed on carbon black than for pure NP. Covalently bound14C in lungs increased with time after exposure to14C‐NP adsorbed to carbon black, reaching levels of approximately 1% of the deposited radioactivity at 7–30 d after exposure, whereas levels of covalently bound14C declined with time after exposure to pure NP. Thus, at 30 d after exposure, the amount of14C covalently bound to lung macromolecules was approximately 10‐fold greater (p< .05) in rats that inhaled14C‐NP adsorbed on carbon black particles than in rats that inhaled pure14C‐NP aerosols. These results suggest that association of NP with carbon black particles augments the interaction of reactive metabolites of NP with target macromolecules. This phenomenon is thought to be related to the slow release of NP from carbon black particles, and may augment the biological effects of inhaled NP when adsorbed on carbon black or similar particles in the environment.

ISSN:0098-4108    

DOI:10.1080/15287398909531256

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This report describes the metallothionein (MT) levels and accumulation of mercury, lead, and cadmium, as well as their interaction with tissue zinc, copper, and iron, and the histopathological changes in kidneys of ducks exposed to methylmercury chloride (MeHgCl), lead acetate (PbAc), and cadmium chloride (CdCl2), singly or in combination for 13 wk. Forty‐eight female Pekin ducks, divided into 8 groups of 6 birds each, were fed diets containing no added metals (control), 8 mg MeHgCl/kg feed, 80 mg PbAc/kg feed, 80 mg CdCl2/kg feed, 8 mg MeHgCl + 80 mg PbAc/kg feed, 8 mg MeHgCI + 80 mg CdCL2/kg feed, 80 mg PbAc + 80 mg CdCl2/kg feed, and 8 mg MeHgCI + 80 mg PbAc + 80 mg CdCL2/kg feed. Cadmium (Cd) when administered alone or in combination caused a 60‐fold increase in kidney MT levels, while methyl‐mercury (MeHg) or lead (Pb) administration caused a threefold increase in kidney MT levels. No significant changes in kidney MT levels were observed when metals were administered concurrently when compared with single‐treatment groups. Residue analysis revealed accumulation of administered metals in kidney tissue. However, lead administration resulted in accumulation of small amounts of this element in kidney tissue. Simultaneous administration of MeHgCl and PbAc significantly increased the accumulation of lead in kidney when compared with PbAc‐treated group. Cadmium when administered alone or in combination caused an increase in the levels of zinc and copper in kidney. Administration of MeHgCl or PbAc either alone or in combination caused increased iron levels in kidney, while cadmium administration either alone or in combination caused decreased iron levels. Administration of cadmium either alone or in combination caused degenerative changes in kidney proximal tubules. The severity of degenerative lesions increased when cadmium was simultaneously administered with other metals. These results indicate that combined administration of MeHg, Pb, and Cd has no significant effect on kidney MT levels or on essential elements in kidney tissue when compared with single metal treatment groups. However, there appears to be an increase in the severity of histopathologic changes.

ISSN:0098-4108    

DOI:10.1080/15287398909531257

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A systematic study has been conducted to determine physiological susceptibility to the potent anticholinesterase soman during and after exposure to different environmental temperatures. Rats were placed in an environmental chamber set at‐1, 7, 15, 23, or 31°C (80% relative humidity, RH) from 0000 to 0800 h. Soman injections were given subcutaneously (sc) at 0600 h (during thermal stress), or at 0810 h after removal from the chamber (injected and tested at 23°C, 60% RH). The measures (taken 30 min after soman injection) included core temperature, grip strength, general state of health, and LD10 estimates (taken 2 h post injection).>

ISSN:0098-4108    

DOI:10.1080/15287398909531258

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Flow cytometric (FCM) DNA content measurements were performed on testicular monocellular suspensions obtained from mice exposed per os to 0, 1, 2, 4, 6, and 7 ml/kg body weight of benzene in order to investigate its cytotoxic action on germ cells. The effects of benzene were measured 7, 14, 21, 28, and 70 d after treatment. Benzene had no effect on testis weight, but FCM analysis showed the relative percentages of some cell subpopulations (tetraploid and haploid cells) to be different from the control pattern, indicating the occurrence of some cytotoxic damage to differentiating spermatogonia. These data demonstrate that spermatogenesis is sensitive to benzene single exposures as evidenced by an altered cell ratio of testicular cell types.

ISSN:0098-4108    

DOI:10.1080/15287398909531259

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Previous assessments of health risks from soil‐adsorbed chemical exposures relied on extrapolations from data derived with pure compounds. However, interactions between chemical and soil can alter the rate, amount, and form of chemical that enters the body, resulting in effects that are different from those that occur after exposures to chemical alone. In this study, male rats were treated dermally with [14C]toluens alone or adsorbed to either a sandy or a clay soil. Both soils produced a higher plasma concentration compared to pure toluene, with a statistical decrease in half‐life of absorption observed after sandy soil‐adsorbed treatment. The time to reach peak plasma concentration, half‐life of elimination, and area under the plasma concentration‐time curve (AUC) were similar for all groups. Skin and fat contained the highest concentration of radioactivity 48 h after all treatments. Pure and soil‐adsorbed toluene were primarily metabolized and excreted via the kidney rather than exhaled. Furthermore, soil treatment did not alter the percentages of the metabolic products.

ISSN:0098-4108    

DOI:10.1080/15287398909531260

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor