摘要:

Residue levels of the chlorinated hydrocarbons p,p'‐DDT (2,2‐bis(p‐chlorophenyl)‐1,1,1‐trichloroethane), p,p'‐DDE (2,2‐bis(p‐chlorophenyl)‐1,1 ‐dichloraethane), hexa‐chlorobenzene (HCB), α‐, β‐, and y‐hexachlorocyclohexane (HCH), aldrin, dieldrin, and polychlorinated biphenyls (PCBs) were determined in human milk of Kenyan mothers living in different areas of Kenya. The main organochlorine contaminants found in all the milk samples analyzed were p,p'‐DDT and p,p'‐DDE. Great regional differences were found, and mean levels of sum DDT and DDT/DDE ratio ranged from 1.1 to 18.7 mglkg milk fat and from 0.7 to 5.7, respectively.

ISSN:0098-4108    

DOI:10.1080/15287398609530944

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The effect of O,O‐dimethyl, S‐ethyl phosphorothioate (OO‐Me S‐Et) on macrophage function and the responses of T‐ and B‐cells of the immune system were investigated using an in vitro model. The role of glutathione (GSH) enhancement of OO‐Me S‐Et suppression of immune responses was studied after either direct culturing with spleen or B‐cells alone or coculture of B‐cells with either B‐ or T‐cells with or without preincubation with OO‐Me S‐Et and glutathione enriched cytosol. The results indicated that OO‐Me S‐Et, when preincubated with CSH, suppresses immune responses through an inhibition of B‐ and T‐cell functions. Both cytotoxic T‐lymphocyte (CTL) generation and antibody production were impaired. In mixing experiments of pre‐treated and normal cells, the inhibitory effect was also observed on macrophages and helper T‐cells responding to a T‐dependent antigen. It appears that the immunosup‐pressive effect of OO‐Me S‐Et is due to impairment of collaboration of T‐ and B‐cells, i.e., mainly due to impairment of T‐cell functions. The immunotoxic effect was only detectable when glutathione was present in the preincubation mixture.

ISSN:0098-4108    

DOI:10.1080/15287398609530945

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Weanling male Sprague‐Dawley rats were gavaged 5 d/wk with 1,3‐dinitrobenzene (m‐DNB) at dosages of 0, 0.75, 1.5, 3.0, and 6.0 mg/kg • d. Males were bred to untreated females during treatment wk 10 and were killed during treatment wk 12. Although males dosed with 3 mg/kg • d inseminated the females and evidence of mating was observed in males dosed with 6 mg/kg • d, none of the males in these groups sired litters. Diminished sperm production (reduced testicular sperm head counts), decreased cauda epididymal sperm reserves, nonmotile spermatozoa, atypical sperm morphology, decreased weights of the testes and epididymides, seminiferous tubular atrophy, and incomplete spermatogenesis were also observed in these groups. Sperm production was also decreased in males dosed with 1.5 mg/kg • d. Changes in the spleen included increased weight at dosages of 1.5 mg/kg • d or higher and splenic hemosiderosis, which ranged from slight in rats treated with 0.75 mg/kg • d to moderately severe in those dosed with 6 mg/kg • d.

ISSN:0098-4108    

DOI:10.1080/15287398609530946

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Administration to rats of oral doses of [14C]‐2‐hydroxy‐4‐methoxybenzophenone (HMB) in the range of 3.01–2570 mg/kg revealed that a dose‐dependent elimination process was operative at the highest dose. Urinary excretion (63.9–72.9% of the dose in 72 h) was the major route for elimination of radioactivity. An intravenous dose (4.63 mg/kg) distributed rapidly throughout the body of rats and appeared in the urine in an amount (67.4%) similar to those for the oral doses. Rats absorbed large portions of doses of [14C]HMB administered topically, either as an ethanolic solution (50, 200, or 800 μg/rat) or formulated in a lotion (50 μg/rat). For rats with biliary cannulas, 36.6% of the radioactivity of an intravenous dose (4.46 mg/kg) appeared in the bile in 4 h; the initial half‐life for biliary elimination was 40 min. In the bile, at least five radioactive components, none of which was intact HMB, were present. The two major components were glucuronides of HMB and demethylated HMB, and a third was probably a sulfate ester of hydroxylated HMB. In urine, there were nine radioactive components, two of which were unchanged HMB and its glucuronide.

ISSN:0098-4108    

DOI:10.1080/15287398609530947

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

It is not clear whether glutathione (CSH) conjugation to 1,2‐dibromo‐3‐chloropro‐pane (DBCP) results in genotoxic activation. Therefore S9, cytosolic, and microsomal fractions from uninduced rat liver were evaluated for their relative ability to activate DBCP in a modified Ames system. The S9 enzymes, either alone or in combination with exogenous CSH, did not enhance the mutagenicity of DBCP; identical results were obtained with cytosolic enzymes. Significant mutagenic activation of DBCP was produced by either S9 or microsomal fractions in the presence of NADPH. Activation was proportional to cytochrome P‐450 concentrations, and was diminished by exogenous GSH. The protection against genotoxicity exerted by CSH did not require cytosolic glutathione S‐transferases (GST). Thus, mutagenic activation of DBCP as obtained with S9 fractions is primarily due to biotransformation by microsomal rather than by cytosolic enzymes. Kinetic studies of cytosol‐catalyzed conjugation of CSH to DBCP revealed tissue‐specific differences in apparent Kmand Vmax. Renal and tes‐ticular CSTs were associated with 28–46% smaller Vmaxvalues when compared to hepatic CSTs (31.2 ± 7.9 nmol/min • mg protein). However, renal and testicular GSTs had relatively higher affinities for DBCP. Thus, extrahepatic tissues possess significant capacity to conjugate CSH to DBCP. DBCP‐CSH conjugates may undergo enzymatic modification by extrahepatic peptidases and β‐lyase to yield other sulfur‐containing moieties that perhaps mediate DBCP's extrahepatic toxicity.

ISSN:0098-4108    

DOI:10.1080/15287398609530948

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The fungal metabolism of the potent mutagenic and carcinogenic nitropolycyclic aromatic hydrocarbon (nitro‐PAH) 6‐nitrobenzo[a]pyrene (6‐NO2‐BaP) was investigated. Cunninghamella elegans was incubated with 6‐NO2‐BaP for periods ranging between 1 and 7 d, and the metabolites formed were separated by high‐performance liquid chromatography and identified by their UV‐visible absorption, mass, and1H nuclear magnetic resonance spectra. The results of our study indicate that C. elegans metabolized 6‐NO2‐BaP to glucoside and sulfate conjugates of 1‐ and 3‐hydroxy 6‐NO2‐BaP and suggests that glycosylation and sulfation reactions may represent detoxification pathways in the fungal metabolism of nitro‐PAHs. Experiments using [C‐3H]‐6‐NO2‐BaP indicated that C. elegans metabolized 62% of 6‐NO2‐BaP within 768 h. Our data also indicated that the nitro group at the C‐6 position of benzo[a]pyrene blocked metabolism at the regions peri to the nitro substituent (C‐7, C‐8 positions) and enhanced metabolism at the C‐l and C‐3 positions. The ability of the fungus C. elegans to metabolize 6‐NO2‐BaP to biologically inactive compounds may have practical applications in the detoxification of nitro‐PAH‐contaminated wastes.

ISSN:0098-4108    

DOI:10.1080/15287398609530949

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Female BALB/c and B6C3F1 mice were examined after a 3‐wk exposure to dietary estradiol (0, 400, 800, 1600, and 3200 ppb) in a purified diet (AIN‐76A) or a natural‐ingredient diet (NIH‐07). Histological findings, which became more prevalent with increasing estradiol dosage in both mouse genotypes, included vaginal hyperkeratosis and mucoid stroma, uterine inflammation, hydrometra and glandular hyperplasia, and ovarian corpora lutea depletion. At the two lower doses of estradiol, responses were generally more prevalent or severe in mice fed the purified diet than in those fed the natural‐ingredient diet. However, in BALB/c mice, several responses to the two higher estradiol doses were greater when estradiol was given in the natural‐ingredient diet rather than in the purified diet. These responses included corpora lutea depletion, vaginal hyperkeratosis, and uterine inflammation and hydrometra. In B6C3F1 mice, most responses to estradiol at concentrations of 400, 800, and 1600 ppm were more prevalent or severe in mice fed the purified diet than in those fed the natural‐ingredient diet. It can be concluded that several responses to estradiol in mice maintained for a 3‐wk period on a purified diet differed significantly from mice maintained on a natural‐ingredient diet.

ISSN:0098-4108    

DOI:10.1080/15287398609530950

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Removal from adipose tissue is an important first step in ultimate removal of many lipophilic xenobiotics from the body. This study concerned the elucidation of mechanisms by which hexabromobiphenyl (HBB) was deposited in and removed from adi‐pocytes. Adipocytes derived from the 3T3L1 cell line of mouse fibroblasts were used to conduct studies in vitro.

ISSN:0098-4108    

DOI:10.1080/15287398609530951

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The toxicity of ozone and nitrogen dioxide is generally ascribed to their oxidative potential. In this study their toxic mechanism of action was compared using an intact cell model. Rat alveolar macrophages were exposed by means of gas diffusion through a Teflon film. In this in vitro system, ozone appeared to be 10 times more toxic than nitrogen dioxide.

ISSN:0098-4108    

DOI:10.1080/15287398609530952

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In this study, the retention and clearance of particles instilled onto the epithelium at two sites in the nasal cavity were examined. Polystyrene microspheres (3 μm geometric diameter) were labeled with141Ce or85Sr and instilled simultaneously on the maxillary and ethmoid turbinates of beagle dogs. The retention and clearance patterns of the microspheres were followed for 30 d after instillation. Tissue samples, excreta content, and autoradiography of the radiolabels provided the basis for defining the fate of the microspheres or the radiolabels dissolved from the microspheres. Early nasal mucus velocity was significantly faster (p < 0.05) from the maxillary turbinate region (2.5 ± 0.7 mmlmin, mean ± SE) than from the ethmoid turbinate region (0.6 ± 0.4 mmlmin). Retention at both instillation sites at 30 d after instillation was approximately 0.7% of the amount initially instilled. Radioactivity was excreted primarily via the feces during the first few days. Radiolabel measured in urine and tissues other than turbinates was small (<0.05% of the initial burden), indicating minimal dissolution of the radiolabel from the particles. Autoradiographs of turbinate tissue revealed particles sporadically located in the epithelial submucosa. From these data, it was concluded that a significant difference in early clearance for particles exists between the ethmoid and maxillary turbinates, but there was no difference in the fraction of particles retained in these two areas for long periods of time.

ISSN:0098-4108    

DOI:10.1080/15287398609530953

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor