摘要:

Cadmium‐resistant populations were derived by exposing monolayer cultures of Chinese hamster ovary (CHO) cells to stepwise increments of Cd2+concentration, [Cd2+]. Clones Cdr20F4 and Cdr30F9 were selected from populations showing normal growth rates in 20 and 30 μM Cd2+, respectively. These variants were compared with CHO and with Cdr2C10, a previously derived clone, in terms of cell survival and Cd2+uptake and partitioning as functions of [Cd2+]. The maximum [Cd2+] to which the various cells may be exposed in suspension culture without effects on growth or survival was 0.2, 2, 26, and 40 μM for CHO, Cdr2C10, Cdr20F4, and Cdr30F9, respectively. Patterns of survival as functions of time exposure to toxic levels of Cd2+ differed—survival of CHO decreased exponentially with time, that of Cdr2C10 displayed a shoulder followed by biphasic exponentially decreasing components, and those of Cdr30F9 and Cdr20F4 also had shoulders followed by exponentially decreasing components and, at longer times, by exponentially increasing components indicative of repopulation. The surival patterns for the resistant variants indicated that (1) there was an initial refractory period (0–4 h) during which no cells were killed, and (2) cell killing occurred primarily during the first 6–10 h of exposure. Thereafter, few were killed and survivors outgrew the populations. Studies of Cd2+uptake and partitioning among intracellular forms provided an explanation for such survival patterns. Investigation of the role of metallothionein (MT) in conferring protection against Cd2+‐mediated cytotoxicity showed that none of the cells is protected significantly by preexisting thlonein. During the first hour of uptake, no protection is ascribable to significant thionein sequestration of Intracellular Cd2+in any of the populations. In the resistant populations, however, Cd2+appears in MT earlier and/or more rapidly than in CHO. As a consequence, the non‐MT Cd2+forms do not continue to increase in these species. Within 4 h of exposure, nuclear and cytoplasmic non‐MT Cd3+concentration level off or decrease in the resistant cells, but continue to increase in CHO. However, none of the cells have identical nuclear or cytoplasmic non‐MT Cd2+contents when exposed to their maximum subtoxic [Cd2+] for 8 h. These levels are significantly higher in the resistant cells, Indicating that there are proportionately more ligands (other than MT) that complex Cd2+in a nontoxic form in these cells. Such ligands have high molecular weights (presumably proteins), either preexist or are very rapidly induced in cells exposed to Cd2+, and do not detectably Increase once MT appears. Possible roles of such ligands in Cd2+detoxification and/or thlonein induction are discussed.

ISSN:0098-4108    

DOI:10.1080/15287398109530011

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Cadmium was measuredin vivoin the left kidney and liver of 82 industrially exposed workers and 10 control subjects. The range of Cd values for the industrial group was 0.9–57 mg for the whole kidney and 0.8–120 ppm for the liver, compared to 0.4–11.8 mg and 0.6–7.9 ppm for the control group. Below 40 ppm in the liver, the kidney Cd burden tended to increase with increasing liver concentration. Above 40 ppm, the kidney Cd content decreased as the liver concentration increased. This biphasic relation between Cd in the kidney and the liver for all subjects showed a critical level of approximately 31 mg Cd In the kidney. Estimates of the critical level by ß2‐microg/obulin and urinary protein measurements yielded critical values of 31–42 mg Cd for the whole kidney (300–400 μg/g for the renal cortex).

ISSN:0098-4108    

DOI:10.1080/15287398109530012

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A significant effect of prenatal exposure to the pesticide Mirex is a fetal edema, which is responsible for many of the toxic effects of this agent. Pregnant rats were given 6 mg/kg mirex on d5½‐1½, a moderate dose that does not cause maternal mortality. The blood of 18½‐ and 20½‐d rat fetuses was tested to determine a possible cause of the edema. There were no significant differences between fetal and maternal plasma or between control and treated fetal plasma with respect to sodium and potassium concentrations or total osmolality. The protein concentration of plasma of treated fetuses was lower than that of controls. This effect was proportional to the degree of edema. The concentration in 20½‐d controls was 25.2 mg/ml, that in mildly swollen treated fetuses 18.1 mg/ml, and that in severely swollen ones 13.5 mg/ml. Polyacryl‐amide gel electrophoresis showed quantitative and qualitative changes in plasma of affected fetuses. The colloid osmotic pressure was also reduced from 8.0 mm in controls and unaffected treated fetuses to 4.8 mm in swollen fetuses. Since lowered plasma protein and colloid osmotic pressure cause tissue edema in adults, they are the probable cause of mirex‐induced fetal edema.

ISSN:0098-4108    

DOI:10.1080/15287398109530013

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Exposure to and absorption of Guthion 50 W.P. (azinphos‐methyl) were estimated in orchardists from the Okanagan Valley in British Columbia who were involved in mixing, loading, and application with ultra‐low volume air blast equipment. Air monitoring and patch techniques were used to estimate exposure, and alkyl phosphate excretion and cholinesterase inhibition were measured to estimate absorption. All workers were issued with standardized cotton shirts, trousers, and long‐sleeved coveralls. All wore half‐face respirators, gloves, boots, and hats. Eight wore rubberized protective clothing in addition. The indirect method of measuring urinary metabolites appeared to be the most sensitive. All workers had quantifiable levels of alkyl phosphates following exposure, and the 24‐h urine samples provided a more reliable estimate than first morning voids. A high correlation was observed between 48‐h alkyl phosphate excretion and amount of active ingredient sprayed. A fluorescent tracer was added to the tank along with the Guthion. The finding of Guthion on patches beneath the clothing was confirmed by the presence of the tracer on the skin. With the ultralow‐volume application used in this study, the rubberized clothing did not appear to be significantly more protective than the heavy coverall. There was no significant depression of either red blood cell or serum cholinesterase activity in any workers.

ISSN:0098-4108    

DOI:10.1080/15287398109530014

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A group of 176 former asbestos workers and 76 unexposed controls of similar age were evaluated and compared for concentrations of serum immunoglobulins, α1‐antitrypsin, carcinoembryonic antigen (CEA), pulmonary function, radiographic appearance of the lungs, rales, cellular atypia and ferruginous bodies in sputum, and smoking habits. Test subjects were evaluated as a single group and also according to years of exposure to asbestos. Both test and control populations were independently subjected to parametric and nonparametric correlation analyses. Partial correlations were also determined for both groups after controlling for age, race, sex, and smoking habits. Analysis of variance was used to compare test and control groups.

ISSN:0098-4108    

DOI:10.1080/15287398109530015

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Recoveries of acepromazine and chlorpromazine from equine plasma were examined. Recoveries of both drugs from plasma were poor under theoretically optimal conditions for basic drugs. When a wide range of extraction pH was examined, it was found that more complete recoveries of these drugs from plasma were achieved at pH 5–6. Use of [3H] chlorpromazine showed that the rate of migration of the drug from an aqueous to a nonpolar environment was much faster at pH 6.0 than at pH 9.2 from both plasma and buffer solutions. Times required for equilibration with agitation were 15 min at pH 6.0, 1 h at pH 9.2, and 2 h at pH 11.0. With these agitation times and pH values, recoveries were more than 95% complete.

ISSN:0098-4108    

DOI:10.1080/15287398109530016

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The possibility of formation of nitrosamine was investigated In animals exposed to a combination of dimethylamine (DMA) and NO2. First, the distribution and covaient binding of DMA and dimethylnitrosamine (DMN) in rats and guinea pigs were determined. The apparent volume of distribution and biological half‐life for [14C]‐DMA or [14C]DMN did not reveal any species difference. In general, there were no marked differences in accumulation of radioactivity in tissues of guinea pigs and rats 4 h after the administration of DMA, while the guinea pig tissues showed higher accumulation after DMN administration. Nucleic acid fractions prepared from liver and lungs of both species following administration of DMN or DMAin vivoshowed much higher covaient binding with DMN than with DMA. Furthermore, the covaient binding of DMN was found to be due to bioactivation, whereas the DMA binding was nonspecific. Since guinea pig liver showed a higher degree of covaient binding than rat liver, this species was used to investigate the possible increase in covaient binding in the presence of N02and DMA as a reflection of DMN formation. There was no evidence of enhancement of covaient binding when animals pretreated with [14C]‐DMA were exposed for various lengths of time to different concentrations of NO2.

ISSN:0098-4108    

DOI:10.1080/15287398109530017

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Pretreatment with HgCI2(2 mg/kg sc) 24 h before administration of thiopental (35 mg/kg ip) significantly potentiated the duration of thiopental sleeping time in adult male rats but did not influence the onset time for anesthesia. The plasma concentration of free thiopental was significantly higher in the Hg‐treated animals 15 and 45 min after thiopental injection (i.e., during the period of thiopental anesthesia), with a concomitant increase of the free thiopental concentration in the brain at 15 min. However, total and free brain thiopental concentrations in Hg‐treated rats at the time of awakening were not different from those in saline‐treated animals. Urinary thiopental remained unchanged from 0 to 2 h, but was increased in the treated urine from 0 to 27 h.In vitrostudies showed a strong inhibition of thiopental binding in the 24‐h Hg‐treated plasma. The results suggest that the prolongation of thiopental anesthesia induced by Hg pretreatment is probably related to changes in the disposition of thiopental in the plasma and brain rather than to an alteration in the sensitivity of the central nervous system.

ISSN:0098-4108    

DOI:10.1080/15287398109530018

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Studies with different avian species have revealed that surface applications of microiiter amounts of some crude and fuel oils that coat less than 10% of the egg surface result in considerable reduction in hatching with teratogenicity and stunted growth. Other studies have shown that the embryotoxicity is dependent on the aromatic hydrocarbon content, further suggesting that the toxicity is due to causes other than asphyxia. In the present study the effects of three polycyclic aromatic hydrocarbons identified in petroleum were examined on mallard (Anas platyrhynchos) embryo development. Addition of benzo[a]‐pyrene (BaP), chrysene, or 7,12‐dimethylbenz[a]anthracene (DMBA) to a synthetic petroleum hydrocarbon mixture of known composition and relatively low embryotoxicity resulted in embryotoxicity that was enhanced or equal to that of crude oil when 10 μl was applied externally to eggs at 72 h of development. The order of ability to enhance embryotoxicity was DMBA > BaP > chrysene. The temporal pattern of embryonic death was similar to that reported after exposure to crude oil, with additional mortality occurring after outgrowth of the chorioallantois. Retarded growth, as reflected by embryonic body weight, crown‐rump length, and bill length, was accompanied by teratogenicity. Abnormal embryos exhibited extreme stunting; eye, brain, and bill defects; and incomplete ossification. Gas chromatographic‐mass spectral analysis of externally treated eggs showed the passage of aromatic hydrocarbons including chrysene through the shell and shell membranes to the developing embryos. These findings suggest that the presence of polycyclic aromatic hydrocarbons in petroleum, including BaP, chrysene, and DMBA, significantly enhances the overall embryotoxicity in avian species.

ISSN:0098-4108    

DOI:10.1080/15287398109530019

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

No. 2 fuel oil was fed to mallard (Anas platyrhynchos) ducklings in concentrations of 0.5 and 5.0% of the diet from hatching to 18 wk of age to assess the effects of chronic oil ingestion during early development. Five growth parameters (body weight, wing length, ninth primary length, tarsal length, and bill length) were depressed in birds receiving a diet containing 5% fuel oil. There was no oil‐related mortality. The 5% fuel oil diet impaired avoidance behavior of 9‐d‐old mallard ducklings compared with controls or ducklings fed 0.5% oil. Open‐field activity was greatly increased in 16‐wk‐old ducklings fed 5.0% oil. Liver hypertrophy and splenic atrophy were gross evidences of pathological effects in birds on the 5.0% oil diet. More subtle effects included biochemical lesions that resulted in the elevation of plasma alanine aminotransferase and ornithine carbamoyltransferase activity.

ISSN:0098-4108    

DOI:10.1080/15287398109530020

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor