摘要:

A study was conducted to evaluate the urinary cadmium levels among 45 nonsmoking sewage sludge farmers of different age groups and exposure. Urinary cadmium was analyzed following standard procedures on a flameless atomic absorption spectrophotometer. Cadmium concentrations were found to be significantly higher when compared with a nonsmoking general population of similar age group with no occupational exposure to cadmium. The mean concentration of 7.07 μg/L of cadmium was found in the farmers exposed to 25 yr of working on the sludge farms. Significantly higher concentrations of cadmium were also detected in the farmers exposed to 10 yr of working on sludge farms when compared with that of control groups.

ISSN:0098-4108    

DOI:10.1080/15287399409531898

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This report consists of an evaluation of 41 soldiers from the infantry, armored, and artillery division, who developed hand dermatitis from their contact with oils and fuel. A special “tailored” supplementary tray with five reagents relevant to their field of work and environment was performed. The reagents that were used were gun oil, hydraulic oil, automotive lubricant (oil) 20/50, white spirit, and car petrol (gasoline). Seven of the 41 patients (17%) showed one or more positive tests to the supplementary tray. The fact that none of the control group of 64 patients not exposed to these substances showed a positive result to the supplementary tray indicates that false positive results are, at least, not probable. It is suggested that soldiers with occupational hand dermatitis should be tested with supplemental aimed trays that are relevant to their work and environment, in addition to the standard trays.

ISSN:0098-4108    

DOI:10.1080/15287399409531899

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The frequency of cassava consumption was investigated among three groups of people representing students from traditional and nontraditional cassava‐consuming environments and cassava processors. Of these, 64% of the students at Obafemi Awolowo University, Ile‐lfe, 38% of those at the Federal University of Technology, Akure, and 44% of the cassava processors consumed cassava products at least once a day, while 4, 35, and 28% of the groups, respectively, were moderate consumers (4–6 times a week). The serum thio‐cyanate level of the processors was significantly higher (0.57 mg/dl) than those of the students (0.38 mg/dl), but there was no significant difference in the urinary thiocyanate level of the three groups. Analysis of cassava and its intermediate and final products for free cyanide, acetone cyanohydrin, and intact glucosides during the production of such cassava products as gari, fufu, and lafun revealed that while the finished products might be safe for human consumption, the workers were probably exposed at different stages of processing to nondietary sources of cyanide.

ISSN:0098-4108    

DOI:10.1080/15287399409531900

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The gaseous fluorocarbon trifluoromethane has recently been investigated for its potential as an in vivo gaseous indicator for nuclear magnetic resonance studies of brain perfusion. Trifluoromethane may also have significant value as a replacement for chlorofluorocarbon fire retardants. Because of possible species‐specific cardiotoxic and anesthetic properties, the toxicological evaluation of trifluoromethane in primates (Papio anubis) is necessary prior to its evaluation in humans. We report the acute cardiac and central nervous system effects of trifluoromethane in eight anesthetized baboons. A dose‐response effect was established for respiratory rate, electroencephalogram, and cardiac sinus rate, which exhibited a stepwise decrease from 10% trifluoromethane. No spontaneous arrhythmias were noted, and arterial blood pressure remained unchanged at any inspired level. Intravenous epinephrine infusions (1 μg/kg) induced transient cardiac arrhythmia in 1 animal only at 70% FC‐23 (v/v) trifluoromethane. Trifluoromethane appears to induce mild dose‐related physiological changes at inspired levels of 30% or more, indicative of an anesthetic effect. These data suggest that trifluoromethane may be safe to use in humans, without significant adverse acute effects, at an inspired level of 30%.

ISSN:0098-4108    

DOI:10.1080/15287399409531901

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Prolonged dietary exposure of female B6C3F1 mice to the trichothecene vomitoxin results in hyperproduction of immunoglobulin A (IgA) with a concurrent immunopathology that mimics human IgA nephropathy. To assess the role of gender and strain in the mouse model, semipurified AIN‐76A diet containing 25 ppm vomitoxin was fed to B6C3F1 male mice and to B6C3F1, BALB/c, C3H/HeN, C3H/Hel, and C57BL/6 female mice for 8 wk, and immunopathologic indicators of IgA nephropathy were compared to mice fed clean diet. At the cessation of the experiment, all treatment groups weighed less than respective controls. Serum IgA was increased in male and female B6C3F1 mice as well as in C3H/ HeJ, C57BL/6, and BALB/c female mice compared to corresponding controls. Serum IgA levels were two‐ to sixfold higher in B6C3F1 male treatment animals compared to female treatment groups from all strains. In contrast, at wk 8 serum IgC levels were unaffected or decreased, and serum IgM was decreased in all groups at wk 8. There was a trend toward increased IgA production by Peyer's patch (PP) lymphocytes isolated from treatment mice as compared to controls in all groups except the C3H/HeJ mice. Notably, IgA levels were 18‐fold higher in B6C3F1 male treatment PP cultures than in B6C3F1 female treatment cultures. Hematuria was significantly greater in treatment mice than respective controls at both wk 4 and 8. Increased mesangial IgA deposition was also detectable in all treatment groups except the C57BL/6 mouse. The results suggested that the male B6C3F1 mouse and the five strains of female mice exhibited many of the immunopathologic effects found in IgA nephropathy and that IgA elevation was more marked in male B6C3F1 than female B6C3F1 mice.

ISSN:0098-4108    

DOI:10.1080/15287399409531902

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Human neuroblastoma cells (line SH‐SY5Y) were used to examine the interaction of single exposure to organophosphorus compounds (OPs) with muscarinic receptors. In this study, SH‐SY5Y cells were exposed for 30 min to concentrations of paraoxon, diisopropyl phos‐phorofluoridate (DFP), phenyl saligenin cyclic phosphate (PSP), and mipafox (N,N'‐diiso‐propyl phosphorodiamide fluoridate) that ranged between 10−9M and 10−3M (10−2M for mipafox). Ability to interfere with muscarinic receptor binding was determined by change in the binding of the nonspecific antagonist [3H]‐N‐methylscopolamine (3H‐NMS). Concentrations of paraoxon >0.5 × 10−3M and PSP 1 × 10−3M significantly inhibited the binding of a saturating concentration of3H‐NMS. Concentrations of >10−5M paraoxon or PSP could significantly inhibit the binding of a half‐saturating concentration of3H‐NMS. Studies using specific antagonists for muscarinic subtypes (pirenzepine for M1, AFDX‐116 for M2, and 4‐DAMP for M3) indicated that SH‐SY5Y cells have muscarinic receptors most sensitive to the specific antagonist for the M3 subtype (IC50 of 10−8M for 4‐DAMP compared to 2.5 × 10−6M and 2.7 × 10−5M for pirenzepine and AFDX‐116, respectively). As M3 receptor stimulation results in formation of inositol phosphates from membrane phos‐phoinositides, the capability of OPs to alter levels of inositol phosphates and agonist‐stimulated increases in inositol phosphate formation was examined. Intact cells were prelabeled with [3H]myo‐inositol and then incubated for 15 min with the OPs before addition of 10−5M to 10−3M carbachol. Levels of inositol phosphates were determined as the amount of aqueous soluble radiolabeled product extracted from the reaction mixture. Paraoxon and PSP, but not mipafox or DFP, decreased basal levels of inositol phosphates in a concentration‐related manner. This could be overcome in cells stimulated with carbachol, a muscarinic agonist, and with sodium fluoride, which does not act at muscarinic receptors. These results indicate that certain OPs, upon acute exposure, interact with muscarinic receptors, but that they also have effects on levels of inositol phosphates that may be associated with another site of action in SH‐SY5Y cells.

ISSN:0098-4108    

DOI:10.1080/15287399409531903

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Investigations were carried out on 3‐chloro‐4‐(dichloromethyl)‐5‐hydroxy‐2(5H)‐furanone (MX), a potent direct‐acting bacterial mutagen found in chlorinated tap water, for the potential to induce 6‐thioguanine (6‐TG) resistant mutations in cultured Chinese hamster V79 cells. The mutagenicity of MX was manifested when cells were treated with MX in Hanks balanced salt solution, but not in serum‐free Eagle's minimal essential medium. A 12‐fold higher mutation frequency over control was obtained at 12.5 μg/ml MX. In addition, the inhibitory effect of MX on metabolic cooperation between cocultivated 6‐TG‐sensitive (6‐TG5) and ‐resistant (6‐TG1) V79 cells was investigated. Recovery of 6‐TG1cells significantly increased at 0.8–2.0 μg/ml MX due to impaired intercellular communication with 6‐TGscells. MX is believed to exert tumor‐promoting and mutagenic activity in mammalian cells.

ISSN:0098-4108    

DOI:10.1080/15287399409531904

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Acute ozone (O3) exposures produce an increase in the apparent permeability of the tracheal epithelium, but the mechanism of this response is poorly understood. Comparison of previous studies suggests that qualitative differences may exist between measurements made in vivo or in vitro. To test this possibility we used both in vitro and in vivo electrophysiolog‐ical techniques to investigate the effects of O3exposure on guinea pig tracheal epithelium. Male Hartley guinea pigs were exposed to either 1 or 2 ppm O3or to filtered air for 3 h and were studied 0, 6, or 24 h after exposure. Air‐exposed animals had in vitro mean tracheal potential (VT) ‐32.0 ± 1.5 mV, conductance (GLT) 2.18 ± 0.22 mS/cm, short‐circuit current llSC) 62.6 ± 3.7 μA/cm, and diameter (D) 2.44 ± 0.10 mm. In vitro properties after 1 ppm O3exposure did not differ at any time point from control. Two parts per million O3increased lLSC, but only at 6 h postexposure. The effect of O3on lLSC, was abolished by amiloride. There were no significant changes in VJ, GLT, or D. In vivo tracheal potential under pentobarbital anesthesia was ‐19.7 ± 1.7 mV. At 6h postexposure to 2 ppm O3, but not at 0 or 24 h, in vivo VTwas increased. Thus, acute exposure of guinea pigs to a high concentration of O3caused a delayed increase in Na+absorption by the trachea with no change in conductance. This indicates that paracellular permeability of guinea pig tracheal epithelium was not substantially increased by acute O3and suggests that enhanced macromolecular uptake in this species probably occurs transcellularly. Furthermore, the increase of in vivo VTfollowing O3exposure is consistent with the in vitro response, indicating that in vivo/in vitro differences are not responsible for the discrepancies between previous electrophysiological and “permeability” studies.

ISSN:0098-4108    

DOI:10.1080/15287399409531905

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The objective of our study was to investigate whether coating the surface of silica with Survanta, a commercially available, bovine pulmonary surfactant, would reduce the in vitro cytotoxicity to alveolar macrophages (AMs), as well as attenuate lung damage in vivo following intratracheal instillation of silica. In the in vitro studies, alveolar macrophages from male Fischer 344 rats were incubated for 1 and 24 h with native or Survanta‐treated silica (0.5 mg/ml). At both time points, the native, uncoated silica caused a dramatic loss of AM viability. The AMs were protected, however, when the silica was treated with the Survanta surfactant. This protective effect was significantly greater after 1 h when compared with 24 h. In the in vivo studies, a high dose of silica (10 mg/100 g body weight) was suspended in Survanta and intratracheally instilled into the lungs of male Fischer 344 rats. A number of biochemical and cellular parameters were measured within the bronchoalveolar lavage fluid (BALF) 1 and 14 d after the instillation exposures to assess lung damage. One day after the instillations, the suspension of silica in Survanta resulted in significant reductions in the silica‐induced increases in total protein, β‐glucuronidase activity, and influx of neutrophils (PMNs) into the airspaces of the lungs. Fourteen days after the instillation exposures, this protective effect was lost. When Survanta was instilled into the lungs 15 min after the intratracheal instillation of silica, a significant reduction also was demonstrated in the silica‐induced elevations in BALF total protein, β‐glucuronidase activity, and influx of PMNs 1 d after the instillation exposures. In an attempt to protect silica‐exposed lungs over a longer period of time, Survanta was instilled into the lungs 15 min after the silica instillation, and then every other day over a 7‐d treatment period. Twenty‐four hours after the last Survanta instillation, slight but significant decreases in the silica‐induced elevations in BALF total protein and β‐glucuronidase activity were observed. The Survanta treatment, however, had no effect in preventing the infiltration of PMNs into the airspaces of the lungs. The results of this study indicate that artificially coating the silica with surfactant phospholipid offers short‐term protection against its toxicity under both in vitro and in vivo conditions.

ISSN:0098-4108    

DOI:10.1080/15287399409531906

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Male Wistar rats were exposed to micronized aerosol concentrations of a14C‐labeled model polycyclic aromatic hydrocarbon (pyrene) at 200, 500, and 800 mg/m3for a period of 95 min. Both the14C label and free pyrene were monitored in the blood, urine, and feces. At the termination of the blood sampling, three of the six rats per dose group were killed and the distribution of [14C]pyrene to eight major tissues was analyzed. The analysis of blood concentration data using a one‐compartment pharmacokinetic model revealed that the uptake and elimination kinetic parameters were dose dependent, for both total radioactivity (pyrene plus metabolites) and for pyrene per se, over the range of exposures used in this study. The ratio of the percent excreted via the urinary and fecal routes, collected over a 5‐d period postexposure was about 1.0 at each exposure level.

ISSN:0098-4108    

DOI:10.1080/15287399409531907

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor