摘要:

Pregnant rats were exposed to drinking water with lead (Pb) concentrations of 0, 30, or 200 mg/l. The resultant pups were sacrificed at 11, 75, and 21 d of postnatal age for the determination of synapses/mm^ in parietal cortex. Synoptic counts from electron micrographs of ethanol phosphotungstic acid stained cortical slices were counted by four observers who were blinded as to treatment (control or 200 mg Pb/l drinking water). A greater than fourfold increase in synoptic counts was observed in layers I, II, and III of rat pups parietal cortex between II and 21 d of age. Pb treatment depressed synoptic counts maximally at 15 d of age. However, Pb‐exposed pups displayed essentially the same synoptic counts us controls by 21 d of age. In a cross‐fostering design, it was shown that prenatal exposure to Pb completely accounted for the delays in synaptogeneis. No significant depression of synoptic counts was observed in pups exposed only during the postnatal period. Blood lead concentrations (Pb'B) were determined during gestation and suckling in both mother and offspring. A dramatic peripartum (partum plus and minus 4 d) peak in Pb‐B was seen in mother and pup. Pup Pb‐B peaked at 80 μg/dl at exposures of 200 mg Pb/I drinking water. In addition to being dose‐dependent, blood Pb levels resulting from the same concentration of Pb in drinking water displayed a significant dependence on litter at time‐points between birth and I yr of age. These data indicate that the substantially elevated blood Pb concentrations that are evident at partum in pups prenatally exposed to Pb might be responsible for the postnatally observed delay in synaptogenesis.

ISSN:0098-4108    

DOI:10.1080/15287398209530283

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Sprague‐Dawley rats were injected sc with lead acetate in suspension, or with sodium acetate (controls) on the d 9 of pregnancy and every 3–4 d thereafter until the pups were 13 or 21 d of age. At termination, testicular homogenates or isolated Sertoli cells were used to study steroidogenesis and gonadotropin binding. Lead had no significant effect on the mother's water and food consumption, on the pup's body or testis weights, on the number of pups and the time of birth, and on the seminiferous tubule diameter. Homogenates of testes of the lead‐treated group converted significantly less (p <0.01) labeled progesterone (14Cor3H) to 5α‐pregnane‐3,20‐dione, 3α‐hydroxy‐5α‐pregnan‐20‐onet17β‐hydroxy‐5α‐androstan‐3‐one (DHT), 3(α,β))‐hydroxy‐5α‐androstan‐17‐one, testosterone/17α‐hydroxyprogesterone, and androstenedione. Sertoli cells from lead‐treated animals converted significantly less (p < 0.01) progesterone to 5α‐pregnane‐3α,20α‐diol, 3α‐hydroxy‐5α‐pregnan‐20‐one, DHT, and 20α‐hydroxy‐4‐pregnen‐3‐one. These data and direct spectrophotometric assays indicated that 3α‐hydroxysteroid oxidoreductase (3α‐HSO), 3β‐HSO, 20α‐HSO, Sctreductase, and C17–20‐lyase had been affected. The receptor studies showed that the binding of [125I]rFSH to testicular receptors was significantly reduced from 35,600 (control) to 25,980 cpm/mg protein (lead). This is the first evidence that lead exposure fin utero and via mother's milk) significantly reduces steroid production and hormone binding in the testis at the onset of puberty.

ISSN:0098-4108    

DOI:10.1080/15287398209530284

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Hair samples from dental and nondental personnel in central Kentucky were collected and analyzed for inorganic mercury. Hair mercury levels in both groups averaged somewhat less than 1.0 μg/g, and the maximum concentration observed was 3.0 μg/g. There was no significant difference in hair mercury content between the two groups. However, a highly significant negative correlation (r = —0.7110; p < 0.0001) was found between hair mercury concentration and age of the donor. A possible explanation of this relationship is presented. The analytical procedures employed provided accuracy and precision in recovering mercury from enriched hair samples.

ISSN:0098-4108    

DOI:10.1080/15287398209530285

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

A cute toxicity of ammonium metavanadate solutions in normal saline (pH 6.7) or 0.1 M Tris‐HCl‐NaCl buffers (pH 7.2 or pH 7.8) was studied in BALB/c mice at 20 mg V/kg. Animals receiving these solutions subcutaneously started to show severe clinical signs 10–15 min postinjection and high mortality rates (45–73%) during the first 3 d. Animals dying because of vanadium toxicity did so only within the first 3 d after injection. NH4VO3‐treated animals showed a tendency to increase their liver and spleen weights as compared to those receiving control solutions. Severe necrosis in lymphoid tissues (thymus, spleen, lymph nodes, and Peyer's patch), pulmonary hemorrhage, and renal acute tubular necrosis were commonly demonstrated in vanadium‐treated animals. Toxicity of NH4VO3solution in 0.1 M Tris‐HCl‐NaCl buffer (pH 7.8) was greatly reduced upon acidification with HCI to pH 6.1 or following boiling for 15 min (final pH of 7.7). Acidification of the solution reduced the mortality rate to 20 from 68%; however, the clinical signs were still severe. Boiling of the solution reduced the mortality rate to zero and moderated the severity of the clinical signs.

ISSN:0098-4108    

DOI:10.1080/15287398209530286

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The effect of methylmercury (MM) on protein synthesis was examined with respect to nutritional deficiency due to decreased food intake, method of amino acid administration, and amino acid uptake. Female rats were administered orally 40 mg MM hydroxide/kg and were compared with both ad libitum and pair‐fed control groups. Synthesis of blood, liver, kidney, and cerebellar proteins of pair‐fed controls was significantly lower than for ad libitum‐fed controls. Relative to ad libitum‐fed controls, MM transiently increased synthesis of blood proteins and then decreased it for blood and liver proteins. In contrast, using pair‐fed controls, MM increased synthesis of blood and liver proteins. Comparison with either control showed MM to increase protein synthesis in the kidney and decrease it in the cerebellum. Intra‐peritoneal and intravenous administration of the [14C] amino acids showed similar results. The action of MM on protein synthesis seemed independent of its action on amino acid uptake, since MM did not affect aminoisobutyric acid uptake in the liver and cerebellum and decreased it in the kidney. In summary, we found that the effect of MM on food intake plays a significant role in the action of MM on protein synthesis and must be accounted for with pair‐fed controls.

ISSN:0098-4108    

DOI:10.1080/15287398209530287

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The acute intraperitoneal LD50 values of hydroxynonachlorodiphenyl ethers (HO‐Cl9‐DPEs) in mice have been determined. The acute toxicity of each of these compounds is compared with that of pentachlorophenol (PCP) and 2‐hydroxy‐2’,4,4'‐trichloro‐diphenyl ether (2‐HO‐Cl3‐DPE; Irgasan DP‐300; Triclosan), a commonly used bactericide. The order of acute toxicity observed was: 2‐HO‐Cl9‐DPE > technical PCP ≈ pure PCP > 3‐HO‐Cl9‐DPE > 4‐HO‐O,‐DPE > 2‐HO‐Cl3‐DPE. Symptomatology following exposure to the HO‐Cl9‐DPEs was similar to that observed for PCP, a known uncoupler of oxidative phosphorylation. 2‐HO‐Cl3‐DPE, however, produced clinical signs suggestive of a suppressive effect on the central nervous system. Data on time response following a lethal dose of each of these compounds was also obtained.

ISSN:0098-4108    

DOI:10.1080/15287398209530288

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Some new organotin(IV) complexes of Schiff bases containing sulfur and fluorine were tested for their activity on axenically grown Entamoeba histolytica trophozoites (strain NIH‐20). Some of the complexes were found to be potentially active at low doses, and one compound, tri‐n‐butyltin (2‐fluorobcnzaldehyde‐S‐benzyldithiocarba‐zate), showed remarkable activity at an extremely low dose even after 48 h.

ISSN:0098-4108    

DOI:10.1080/15287398209530289

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Phenthoate [O,O‐dimethyl S‐(α‐ethoxycarbonyl)benzyl phosphorodithioate] was rapidly hydrolyzed by rat liver and plasma carboxylesterases to the corresponding nontoxic metabolite, phenthoate acid. A partially purified enzyme isolated from rat liver microsomes was sevenfold more effective in hydrolyzing phenthoate than the microsomal fraction. O,S,S‐Trimethyl phosphorodithioate (TMPDT) and O,O,S‐trimethyl phosphorothioate (TMPT), two impurities present in technical formulations of phenthoate, were examined for their inhibiting effects on the esterase degradation of [phenyl‐14C] phenthoate in vitro. Incubation of [14C]phenthoate with rat liver and plasma carboxylesterases in the presence of these impurities greatly diminished the amount of phenthoate acid formed. TMPDT was superior in its inhibitory action against rat liver carboxylesterase to that of TMPT. TMPDT was equipotent in inhibiting crude rat liver and plasma carboxylesterases, and TMPT was more effective in inhibiting plasma carboxylesterase than rat liver carboxylesterases.

ISSN:0098-4108    

DOI:10.1080/15287398209530290

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Following several reports of human allergic hypersensitivlty, the ability of 2,4‐D (2,4‐dichlorophenoxyacetic acid) to elicit 2,4‐D‐specific IgE antibodies and delayed‐type hypersensitivity in BALB/c mice was studied. 2,4‐D‐specific IgE antibodies were detected in mouse sera following the second intraperitoneal immunization with I, 10, or 100 μg 2,4‐D‐keyhold limpet hemocyanin conjugate with aluminum hydroxide adjuvant. Specific IgE was determined with the rat passive cutaneous anaphylaxis test using a conjugate of 2,4‐D with bovine serum albumin for challenge. The highest antibody titers and a measurable response in all mice were seen in the group that received 1 μg of 2,4‐D conjugate. Dinitrophenyl‐specific IgE was measured at all intervals examined in mice immunized with a dinitrophenyl‐keyhole limpet hemocyanin conjugate. 2,4‐D applied epicutaneously on 2 d or over 4 wk failed to elicit delayed‐type hypersensitivity as measured by change in ear thickness, incorporation of 5‐[125I] iodo‐2'‐deoxyuridine, or histology following challenge on the ear. No 2,4‐D‐specific IgE antibodies were detected in serum during the 4‐wk sensitization period. Similar treatment with a known sensitizer, dinitrofluorobenzene, produced delayed hypersensitivity. Following 4 wk of dosing, low titers of dinitrophenyl‐specific IgE antibodies were elicited.

ISSN:0098-4108    

DOI:10.1080/15287398209530291

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The effect of vitamin E deficiency in male Sprague‐Dawley rats upon lipid peroxidation in lung tissue was examined by measuring malonaldehyde and lipid epoxide production. In addition to controls, some animals were also exposed to 3 ± 0.7 ppm NO2continuously for 7 d in order to study the effects of oxidant stress on lung lipid peroxidation and vitamin E content. The observed changes in malonaldehyde and epoxide content could serve as good indices of lipid peroxidation, particularly under conditions of vitamin E deprivation. The responses measured indicated an inverse relation in the lung between tissue vitamin E content and quantity of lipid peroxidation products. Measurement of lipid epoxides served as a reliable indicator of lung tissue lipid peroxidation. Finally, NO2inhalation appeared to elicit a response characterized by increased assimilation of vitamin E into lung tissue.

ISSN:0098-4108    

DOI:10.1080/15287398209530292

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor