摘要:

AbstractDiminution rate of body burden of chelatable lead (CPb) after injection of calcium disodium ethylenediamine tetraacetate (CaEDTA) was estimated at between 0.7 and 0.4% per week in two lead workers after termination of lead exposure. Hence, alteration in body burden of CPb during the week after a single injection of CaEDTA was simulated by two different equations. The first equation was (1 + α−1.3β)6(1–1.03k+ α)A= 0.993Aor 0.996A, whereA= body burden of CPb just before CaEDTA injection; α = proportion of CPb converted from non‐chelatable lead (NPb) toAduring the 24 h after CaEDTA injection;k= proportion of 24‐h mobilization yield of lead by CaEDTA toA; and β = proportion of 24‐h spontaneous urinary lead excretion toA. This equation was based on the assumption that the amount of lead converted to CPb during 24 h was proportional to the initial level of CPb. The second equation, i.e. (1–1.03k) (1–1.3β)6A+ {(1–1.3β)6+ (1–1.3β)5+ … + (1–1.3β) + 1} αA= 0.996Aor 0.996A, assumed that the amount of lead converted to CPb during 24 h was nearly constant during a week after CaEDTA injection. The conversion rate (α) was obtained as a solution of each equation after determination ofkand β according to our model. It was estimated that the amount of lead corresponding to 2% of body burden of CPb, i.e. 0.23 mg and 0.35 mg, was converted from NPb to CPb during the 24 h after CaEDTA injection in the two lead workers with blood lead concentrations of 44 μg per 100 g and 61 μg per 100 g, respectively. A previous model for estimating body burden of CPb from mobilization yield of lead by CaEDTA was amen

ISSN:0260-437X    

DOI:10.1002/jat.2550030102

出版商:John Wiley&Sons, Ltd.    

年代:1983

数据来源: WILEY

摘要:

AbstractThe toxic side‐effects and anti‐inflammatory activity of combination treatment of Sprague‐Dawley rats with indomethacin and Probon, a new type of analgesic, were investigated. Following four weeks of treatment with a combination of these two drugs, the characteristic gastrointestinal side‐effect of indomethacin was markedly reduced. Mortality resulting from administration of the drug combination was significantly lower than that resulting from indomethacin treatment alone. The reduced toxicity of indomethacin in combination with Probon is probably due to a change in metabolism produced by the hepatic microsomal enzyme inducer, Probon. The anti‐inflammatory effect was also investigated using a contact thermographic method following one, three or seven days pretreatment. The advantage of this combination is that, using a higher dose of indomethacin in combination with the minor analgesic, we could achieve a more reliable anti‐inflammatory effect together with a pain‐k

ISSN:0260-437X    

DOI:10.1002/jat.2550030103

出版商:John Wiley&Sons, Ltd.    

年代:1983

数据来源: WILEY

摘要:

AbstractAdenylate cyclase activity was measured in plasma membranes isolated from Morris Hepatoma 7800 and from control and host livers. The only difference found in tumor enzyme activity was the lack of response to glucagon. The membrane‐binding capacities for the pancreatic hormones insulin and glucagon were measured. Hepatoma membranes did not bind glucagon. Insulin‐binding parameters could not be determined because of high non‐specific binding. The plasma levels of insulin in the tumor‐bearing animals were approximately half of those found in controls, whereas the glucagon levels in plasma were 50% higher in tumor‐bearing animals. Thyroxine and triiodothyronine plasma levels were reduced in tumor‐bearing rats, while the thyroid‐stimulating hormone level was within normal limits. The amount of cAMP (275 pmol g−1) and cGMP (3.6 pmol g−1) in the tumor were lower than in the host and control livers, but the ratio of cGMP to cAMP in the tumor was increased by a factor of 2. These results are discussed with respect to control mechanisms of cell proliferation in comparison with other hepato‐p

ISSN:0260-437X    

DOI:10.1002/jat.2550030104

出版商:John Wiley&Sons, Ltd.    

年代:1983

数据来源: WILEY

摘要:

AbstractTwo varieties of native and chemically treated slate dust were testedin vitrofor their hemolytic effects and the extent of silicic acid dissolution in various physiological fluids. The extent of hemolysis was found to be proportional to the degree of dissolution of dust constituents. Membrane lysis by the dust appeared to be prevented by coating it with polyvinyl pyrrolidone, serum proteins and pulmonary lavage lipids. The significance of the findings is discussed.

ISSN:0260-437X    

DOI:10.1002/jat.2550030105

出版商:John Wiley&Sons, Ltd.    

年代:1983

数据来源: WILEY

摘要:

AbstractA search of 3600 indexed pathology cases has disclosed pulmonary fibrosis in 29 welders. Scanning electron microscopy of biopsy material revealed macrophages laden with inorganic particulates which have characteristics compatible with welding aerosols. In order to establish a possible relationship between fibrotic reaction and welding‐fume exposure, the fibrogenic potential of some 11 different welding fumes and metallic aerosols, considered to be reference standard surrogates for the commonly used welding technologies and applications responsible for 70% of welders exposure, were screened using the Rat Peritoneal Macrophagein vitrobioassay. Only one class of fumes, that from the manual metal arc welding of stainless steel, showed distinct fibrogenic potential. This fume is, however, not common to more than four or five of the heretofore 90 cases of pulmonary fibrosis reported among welders. Thus, although insoluble Cr(VI) is probably the active fibrogen in stainless steel fumes, an etiological factor common to all fibrogenic welding exposures must be sought. It is tentatively proposed to be NO2, a potent experimentalin vivofibrogen copiously produced by certain welding processes and ubiquitous at low concentrations in the welding environmen

ISSN:0260-437X    

DOI:10.1002/jat.2550030106

出版商:John Wiley&Sons, Ltd.    

年代:1983

数据来源: WILEY

摘要:

AbstractFractions derived from solvent‐refined coal‐II (SRC‐II) heavy distillate (HD) were tested for their skin tumor initiating activity. Basic (BF), basic tar (BTF), neutral tar (NTF) and polynuclear aromatic (PNA) fractions were prepared from HD by solvent extraction. These fractions were tested for their initiating activities by applying a single dose to the shaved back of male, CD‐1 mice (Charles River, Portage, MI). Positive control groups were initiated with either dimethylbenz[a]anthracene (DMBA) or benzo[a]pyrene (BaP). Two weeks after initiation, all mice received twice weekly applications of 5 μg of phorbol myristate acetate (PMA) for a period of 24 weeks. Papillomas were noted and recorded for each animal at the time of PMA application. Heavy distillate and its fractions all showed initiating activity. However, the incidence of mice with tumors, the rate of tumor appearance and the total number of tumors varied with the test material. The tumor responses after initiation with HD, NTF and BTF were similar to that found with BaP, but lower than that with DMBA. Somewhat lower activity was found for BF and PNA. Even lower activity was found with a distillate boiling from 800 to 850°F and no activity was found with a 300 to 700°F distillate. These data are in general agreement with the results of long‐term, skin painting assays, suggesting that initiation/promotion (I/P) may be useful for studying the tumorigenicity of coal‐der

ISSN:0260-437X    

DOI:10.1002/jat.2550030107

出版商:John Wiley&Sons, Ltd.    

年代:1983

数据来源: WILEY

摘要:

AbstractA preliminary study of the pharmacokinetics of methylmercury was performed in sheep after a single intravenous dose of203Hg‐labeled methylmercury. Blood samples were taken periodically, and plasma and whole blood203Hg were determined. Blood and plasma203Hg concentrations exhibited a biphasic exponential decline. The half‐time for the major component was 14.6 days for plasma203Hg and 14.1 days for whole blood. There was a uniform distribution of203Hg between red cells and plasma throughout the study. A red cell to plasma concentration ratio of 14.9:1 was obtained, with approximately 88% of the203Hg in blood associated with the red cell fraction. Both the feces and the wool represented major routes of excretion. Approximately 18% of the dose was present in the wool taken on day 8. This is compared with a total excretion in the feces of 11.5% of the dose over the same time course. The total of 29.5% compares favorably with a reduction of 32.5% in the terminal component of the whole blood curve. Sequential analysis of wool from the root end revealed increasing concentrations of203Hg to a peak. Using the first appearance of the203Hg label in the wool as a marker to determine the wool growth rate, the203Hg in wool shewed an exponential decline with a half‐time similar to that seen for whole blood and plasma. The wool to blood ratio was estimated to be approximately 120:1. Tissue analysis at sacrifice revealed a rather uniform distribution of203Hg label in the brain. Somewhat lower levels were observed in the spinal cord and ganglia. Kidney had the highest203Hg concentration, and edible muscle had approximately six times the concentration measured in blood. The concentration of203Hg was three times higher in bile than in plasma, consistent with the substantial fecal excretion observed. The sheep may be a useful animal model for studying regional deposition of methylmercury in the CNS and mechanisms of methylmercury deposition into

ISSN:0260-437X    

DOI:10.1002/jat.2550030108

出版商:John Wiley&Sons, Ltd.    

年代:1983

数据来源: WILEY

摘要:

AbstractThe tissue distribution, elimination and covalent binding of 2,3‐14C‐ and 1‐14C‐acrylonitrile (VCN) were studied in male Sprague—Dawley rats given an oral dose of 46.5 mg kg−1. Exhalation of unchanged VCN,14CO2and H14CN was monitored at selected intervals. Only 5% of the total dose administered was recovered as unchanged VCN. Rats given 2,3‐14C‐VCN exhaled only 2% of14C activity as14CO2and none was recovered as H14CN, whereas rats given 1‐14C‐VCN exhaled about 12% of14C activity as14CO2and 0.5% as H14CN. In the initial 24 h, 40% of radioactivity from 1‐14C‐VCN appeared in urine, while 60% was recovered in the urine of rats given 2,3‐14C‐VCN. The red blood cells retained significant amounts of radioactivity from both the compounds for more than 10 days after administration, whereas the14C activity in plasma declined sharply. The highest level of radioactivity from both compounds was recovered in the gastrointestinal tract. In liver, kidney, brain, spleen, adrenal, lung and heart tissues the unbound percent radioactivity decreased, while irreversible percent covalent binding to macromolecules in relation to total increased concomitantly. Subcellular fractionation of the tissues showed that most of the covalently bound radioactivity was distributed in non‐cytosolic fractions. As compared to 1‐14C‐VCN administered animals, the percentage of covalent binding of 2,3‐14C‐VCN was significantly higher even 72 h after dosing. The relationship between covalent binding an

ISSN:0260-437X    

DOI:10.1002/jat.2550030109

出版商:John Wiley&Sons, Ltd.    

年代:1983

数据来源: WILEY

摘要:

AbstractThe effect of hexadecane on the intestinal excretion of hexachlorobenzene was studied in female Sprague‐Dawley rats dosed twice with14C‐hexachlorobenzene at 50 mg kg−1per os. Injection of 75 mgn‐hexadecane into ligated and unligated segments of the intestine increased concentrations of hexachlorobenzene in intestinal contents by about two‐ or three‐fold in jejunal and ileal segments, and about two‐fold in the cecal—colon segment. The jejunum appeared to be the site of greatest excretion of hexachlorobenzene, followed by the ileum, the cecum and the colon. This order is opposite to our previous data from animals with an undisturbed intestinal passage. The apparently greater excretion of hexachlorobenzene into the small intestine is probably due to its much larger surface area than that of the large intestine. However, the residency time of luminal contents in the large intestine normally exceeds that in the small intestine by about 20–40‐fold, which apparently more than compensates for the difference in relative surface area between small and large intestine. Thus, residency time appears to be a more important factor than surface area in determining the intestinal elimination of hexachlorobenzene. These results with hexachlorobenzene are probably typical of physiological disposition of lipophilic halogenated hyd

ISSN:0260-437X    

DOI:10.1002/jat.2550030110

出版商:John Wiley&Sons, Ltd.    

年代:1983

数据来源: WILEY

摘要:

AbstractA combination of liquid—liquid extraction and thin‐layer chromatography permits rapid identification of a large variety of drugs in pharmaceutical or street dosage forms, or in biological materials. The system utilizes selective pH extraction combined with internal standards. Limits of sensitivity are in the sub‐microgram level. The procedure is rapid and requires minimal equipment and training of personnel. It can be applied to situations in toxicology involving both clinical and forensic de

ISSN:0260-437X    

DOI:10.1002/jat.2550030111

出版商:John Wiley&Sons, Ltd.    

年代:1983

数据来源: WILEY