摘要:

Reports that ribavirin was teratogenic in animals raised concerns of female health care personnel about possible occupational exposure during the care of infants having respiratory syncytial virus infections. Under simulated operational conditions, experiments were conducted to measure ribavirin residues in room air, in surface wipe samples, and in personal sampling devices worn by volunteers. There was exposure to a dispersible dust, presumably dried ribavirin, deposited inside the croupette or hood and on the bedding. Based on personal sampler data, it was estimated that, in a 12‐h shift, the primary health care individual could inhale 2.4–9.1 μg ribavirin/kg bw‐d. Recommendations to reduce the exposure of staff included the wearing of appropriate surgical gloves and a NIOSH‐approved disposable respirator for dusts and mists while attending to the needs of the patients.

ISSN:0098-4108    

DOI:10.1080/15287398909531324

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Fly ash was collected from two municipal refuse incinerators. It was analyzed for heavy metals, elements, and a wide range of toxic organics. It was resuspended in air for inhalation exposure of guinea pigs. These animals were exposed at high concentrations of each ash 6 h/d for 5 d, and tissues were taken 45 d after the exposure. Following the first exposure and after each daily exposure the ventilatory response of these animals upon challenge with CO2was found to be depressed. Recovery occurred following exposure. Heavy metals, cadmium, lead, zinc, and mercury were elevated in the lungs of these animals. Histologic evaluation of pulmonary tissue revealed multifocal pneumoconiosis. Interstitial infiltration by macrophages and smooth muscle hypertrophy of blood vessels and bronchioles were also observed. There was no evidence of a dioxinlike toxic effect following inhalation of these ashes.

ISSN:0098-4108    

DOI:10.1080/15287398909531325

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The carcinogenic effects in male and female F344 rats of four nitrosodialkylureas containing methyl or ethyl groups have been compared by two modes of administration, gavage in oil solution or dissolved in drinking water. Weekly doses of 20 and 40 μmol were given to each rat by either route and treatment lasted usually 30 wk, resulting in a total dose per rat of 0.6 or 1.2 mmol. Nitrosodimethylurea and nitroso‐1‐methyl‐3‐ethylurea gave rise primarily to tumors of the nervous system, whereas nitrosodiethylurea and nitroso‐1‐ethyl‐3‐methylurea gave rise to tumors of the mammary gland, lung, intestinal tract, nervous system, and testicular mesotheliomas. The effect of nitrosodimethylurea was weaker than that of the other three compounds, as measured by rate of mortality with tumors. Drinking water treatment was less effective than treatment by gavage, by the same criterion. The tumorigenic effects paralleled those of the corresponding monoalkylnitrosourea, suggesting the presence in the target organs of receptors for which ethylnitrosoureas or methylnitrosoureas, respectively, have affinity.

ISSN:0098-4108    

DOI:10.1080/15287398909531326

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We have studied the effect of acute induction of metallothionein on the biliary excretion of a bolus of metal in the rat. Female Sprague‐Dawley rats were administered zinc chloride (6.5 mg/kg) or dexamethasone (2 mg/kg), ip in saline daily for 3 d; control animals received saline alone. Zinc causes a 17‐fold induction in hepatic metallothionein levels, while dexamethasone caused a 5‐fold induction. A bolus of metal chloride, either zinc, mercury, or cadmium, 1 mg/kg iv, was administered, and bile and plasma samples were collected and analyzed for metal content. At 3 h the rats were killed, livers excised, and both metallothionein and the metals associated with metallothionein estimated.

ISSN:0098-4108    

DOI:10.1080/15287398909531327

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The mechanism and consequences of the serum thyroid hormone lowering effect of perfluorodecanoic acid (PFDA) were examined. Thyroid and pituitary gland functions in PFDA‐treated rats were assessed by measuring radioiodine uptake from the circulation and the ability of the thyroid gland to secrete thyroxine (T4) and triiodothyronine (T3) in response to thyrotropin‐releasing hormone (TRH) stimulation. Serum levels of reverse triiodothyronine (rT3) were measured to test for possible conversion of T4to a biologically inactive product and the displacement of radiolabeled T4from rat albumin in vitro by PFDA was examined. Finally, changes in activity of the thyroid hormone‐sensitive liver enzymes glycerophosphate dehydrogenase (CPD) and malic enzyme (ME) in response to PFDA were analyzed. Functional activities of the thyroid and/or pituitary glands appear to be somewhat depressed by PFDA treatment. There was no increased conversion of T4to rT3. PFDA displaced radiolabeled T4from rat albumin with an affinity similar to thyroxine. The activities of both GPD and ME were significantly increased in livers from PFDA‐treated rats. These results suggest that decreased serum levels of thyroid hormones may be due to (1) reduced responsiveness of the thyroid and/or pituitary glands to hormonal stimulation and (2) a displacement of circulating hormones from plasma protein binding sites by PFDA. Increased activity of the liver enzymes CPD and ME does not reflect the reduction in circulating thyroid hormones and indicates that PFDA‐treated rats are apparently not functionally hypo‐thyroid at the tissue level.

ISSN:0098-4108    

DOI:10.1080/15287398909531328

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Exposure of prepubertal, pubertal, and adult mice to 0, 8, 16, 32, 40, or 48 mg 1,3dinitrobenzene (m‐DNB)/kg body weight and measuring responses 1–25 d posttreatment (dpt) demonstrated significant effects on testicular function only at 48 mg/kg dosage. m‐DNB had no effect on body or testis weights with the exception of reduced adult mouse testis weights at 22 dpt with 48 mg/kg (p<.05). None of the exposures resulted in detectable levels of germinal epithelial cells in the ductus epididymis. Exposure of prepubertal and pubertal mice to m‐DNB caused only minimal nonsignificant changes in the relative percent of testicular cell types present up to 25 dpt. The adult mice testicular cell type ratios, in particular the round and elongating spermatid populations, changed significantly at doses of 48 mg/kg. Also, a reduction in the percent tetraploid cells occurred at d 1, suggesting these cells may be a primary target of m‐DNB action.

ISSN:0098-4108    

DOI:10.1080/15287398909531329

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Exposure of 100‐d old rats to 1,3‐dinitrobenzene (m‐DNB) at dosages up to 48 mg/kg resulted in disruption of spermatogenesis as measured by flow cytometry (FCM) of acri‐dine orange‐stained sperm and testis cells. One day (d 1) after a single exposure to 48 mg/kg m‐DNB, FCM measurements of caput epididymal fluid cells demonstrated the presence of testicular germinal epithelial cells apparently sloughed off into the epididy‐mis. Also, at d 1 after the same exposure, a decrease in pachytene spermatocytes was observed. By d 76 after exposure to 32 or 48 mg/kg, testicular damage was evidenced by an alteration of cell type ratios in FCM‐analyzed populations of testicular cells. Extensive recovery of cell type ratios occurred by d 32. At d 16, dosages of 32 and 48 mg/kg caused alterations of sperm chromatin structure as determined by the flow cytometric sperm chromatin structure assay (SCSA) 48 mg/kg caused alterations at both d 76 and d 32.

ISSN:0098-4108    

DOI:10.1080/15287398909531330

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Ultrafine metal oxides and SO2react during coal combustion or smelting operations to form primary emissions coated with an acidic SOxlayer. Ongoing work in this laboratory has examined the effects of sulfur oxides on pulmonary functions of guinea pigs. We have previously reported that 20 μg/m3acidic sulfur oxide as a surface layer on ultrafine ZnO particles decreases lung volumes, decreases carbon monoxide diffusing capacity, and causes lung inflammation in guinea pigs after 4 daily 3‐h exposures. It also produces bronchial hypersensitivity following a single 1‐h exposure. The importance of this surface layer is demonstrated by our observation that 200 μg/m3of sulfuric acid droplets of equivalent size are needed to produce the same degree of hypersensitivity.

ISSN:0098-4108    

DOI:10.1080/15287398909531331

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Male Sprague‐Dawley rats administered with a sublethal acute dose of carbofuran (1.5 mg/kg, sc) developed the observable toxic signs of anticholinesterase nature within 5–7 min. The toxic signs with increasing propensity to maximal severity including tremors, generalized muscle fasciculations, and convulsions were evident during 15 min to 1 h and lasted for 2 h. Thereafter, signs were seen up to 3 h with reduced intensity. By the end of 3.5 h toxic signs were completely subsided. Maximal acetyl‐cholinesterase (AChE) inactivation occurred at 1 h in discrete brain regions (cortex, stem, striatum, and hippocampus) and hemidiaphragm muscle when most severe signs of toxicity were also evident. A single sc dose of memantine HCI (MEM, 18 mg/kg) and atropine sulfate (ATS, 16 mg/kg) 60 and 15 min, respectively, prior to carbofuran administration completely prevented the expected gross toxic signs and significantly (p<.01) attenuated the carbofuran‐induced inhibition of AChE activity. When given therapeutically, this combined treatment completely reversed the clinical evidence of carbofuran toxicity within 15 min and also markedly reduced AChE inactiva‐tion. Memantine or atropine when given alone was less effective compared to their combined administration. The results of this study suggested that, in addition to cholinolytic effects of atropine, memantine may prevent and antagonize the acute toxicity of carbofuran by (a) protection of AChE activity and its rapid reactivation from inhibition and (b) rapid elimination of carbofuran.

ISSN:0098-4108    

DOI:10.1080/15287398909531332

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

VIRUSES IN WATER SYSTEMS: DETECTION AND IDENTIFICATION By J. C. BlockandL. Schwartzbrod, VCH Publishers, Inc., New York, 1989, 136 pp., $39.50.

ISSN:0098-4108    

DOI:10.1080/15287398909531333

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor