摘要:

4‐Aminoimidazole‐5‐carboxamide, a component of human urine derived from the de novo purine biosynthetic pathway, was evidenced to undergo in vivo diazotization in rats following its sequential administration with NaNO2. The diazotization product, 4‐diazoimidazole‐5‐carboxamide, undergoes intramolecular cyclization to yield 2‐azahypoxanthine, the urinary presence of which was confirmed mass spectrometrically. 4‐Diazoimidazole‐5‐carboxamide demonstrated dose‐related mutagenicity in Salmonella typhimurium TA 100 and represents a potent electrophilic reactant similar to the proposed ultimate carcinogenic forms of arylalkylnitrosamines and arylnitrosamides. It is suggested that aryl and heterocyclic diazo compounds, as a class, warrant further study as environmental electrophiles representing potential biological hazard.

ISSN:0098-4108    

DOI:10.1080/15287397709529507

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The oxygen dissociation curve of partially NO‐liganded hemoglobin of human erythrocytes is measured. As the percentage of NO ligation increases, the affinity of nonliganded hemoglobin for oxygen increases and the heme‐heme interaction decreases; furthermore, methemoglobin is formed. Therefore, NO affects the oxygen transport function of hemoglobin, decreasing the oxygen supply to peripheral tissues, because of (1) simple diminution of the available hemoglobin by the tightly bound NO, (2) the high affinity of hemoglobin for oxygen, and (3) the inevitable formation of methemoglobin.

ISSN:0098-4108    

DOI:10.1080/15287397709529508

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Dosages of 20 and 10 ppm methylmercury were toxic to rabbits while 1 ppm did not produce clinical signs or death. Serum alkaline phosphatase levels were elevated in all rabbits exposed to methylmercury. Methylmercury‐exposed rabbits challenged to A/PR8 influenza virus had hemagglutination inhibition titers as much as four times lower than those of controls. Histopathologic lesions were found in the cerebellum of rabbits that died. The most significant features of this study were that methylmercury chloride suppressed the humoral immune system and resulted in increased serum alkaline phosphatase levels, which may aid in diagnosis when methylmercury poisoning is suspected.

ISSN:0098-4108    

DOI:10.1080/15287397709529509

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Three days after a single intraperitoneal injection of lead chloride (10 mg/kg) there was a twofold increase in the incorporation of [14C]thymidine into renal DNA. The observed elevation in DNA synthesis was preceded by an enhancement of [14C]orotic acid incorporation into kidney RNA. In plumbic rats, the concentration of renal cyclic AMP was significantly reduced from day 3 through day 7, while the levels of putrescine, spermidine, and spermine remained generally unchanged throughout the experimental period. As in the case of kidney, lead treatment increased (twofold) orotic acid incorporation into RNA in liver and lung. In contrast, exposure to lead produced a reduction in the amount of thymidine incorporated into hepatic and pulmonary DNA. In both liver and lung, treatment with lead tended to lower the concentrations of three polyamines, putrescine, spermidine, and spermine. While exposure to this nonessential element decreased the level of cyclic AMP in hepatic tissue, a significant rise to 152% of control values was noted after 24 hr in lungs of plumbic animals. The data point to a degree of diversity in the metabolic responsiveness of certain tissues to lead exposure and suggest that this metal may not be an adequate experimental tool in the study of DNA replication.

ISSN:0098-4108    

DOI:10.1080/15287397709529510

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Eleven male workers from the polymerization department of a vinyl chloride factory, seven people employed in the laboratory of another vinyl chloride plant, and ten controls from outside the factory environment were examined for the presence of chromosome aberrations in blood lymphocytes. Chromosome anomalies such as fragments, rings, translocations, and dicentrics were observed in most of the workers from the polymerization department. However, the medical history of these workers shows that they received frequent radiographs of the hands, feet, vertebral column, and digestive tract. It is therefore impossible to determine whether these chromosome anomalies result from vinyl chloride exposure.

ISSN:0098-4108    

DOI:10.1080/15287397709529511

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Eight methylated benzene and five methylated naphthalene compounds were injected ip into adult male mice daily for 3 days. On the fourth day livers from control and treated mice were compared with regard to weight, microsomal N‐ and O‐demethylase activity, and various spectral characteristics of microsomal cytochrome PASO. Three methylated benzenes and one methylated naphthalene produced significant increases in liver weight/body weight ratios, O‐demethylation of p‐nitroanisole, N‐demethylation of aminopyrene, or a combination of these.

ISSN:0098-4108    

DOI:10.1080/15287397709529512

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The hygroscopic nature of sulfuric acid mist has not been totally appreciated in previous toxicological work. Sulfuric acid mist, by adsorption or desorption of water, equilibrates rapidly with the relative humidity of its environment. The measured particle diameters of a given sulfuric acid mist will increase in size as the particles adsorb water on entering the respiratory tract. For a dry climate of 5% relative humidity, sulfuric acid mist particles will triple in size in the respiratory tract. At 60% relative humidity, particles will double in size, while particles in humid regions will increase very little. In the respiratory tract, the particles will deposit according to their size at 98% relative humidity. In order to compare toxicity data for sulfuric acid mist, relative humidity must be carefully recorded throughout the experimental procedure.

ISSN:0098-4108    

DOI:10.1080/15287397709529513

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Four experiments were conducted using weanling Wistar rats to determine whether chlorinated cake flour or its constituents were toxic. Levels of 0.2 and 1.0% chlorine added to unbleached cake flour significantly (p <0.01) reduced growth rate by 20.7 and 85.2% and increased liver weight relative to body weight by 16.7 and 25.3%, respectively. Lipids extracted from flour chlorinated at the same levels had similar effects. Rat chow diets containing 0.2 and 0.6% chlorine in the form of chlorinated wheat gluten reduced growth rate and increased liver weight as a percentage of body weight. A rat chow diet containing 0.2% chlorine as chlorinated flour lipids increased absolute liver weight by 40%, kidney by 20%, and heart by 10% compared to pair‐fed controls.

ISSN:0098-4108    

DOI:10.1080/15287397709529514

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Stimulation of [3H]thymidine incorporation in the lungs of hamsters exposed singly and repeatedly to 10 ppm NO2was studied. Within 24 hr of the first exposure to NO2, the response was characterized by a marked increase in [3H]thymidine labeling in the bronchi, bronchioles, and alveolar ducts, but not in the trachea or the peripheral alveoli. If, after the first NO2exposure, subsequent exposures were repeated daily, no further stimulation of [3H]thymidine incorporation was observed in any part of the respiratory tract. However, if the interval between the first and subsequent exposures was 2–3 days rather than 1 day, stimulation of [3H]thymidine incorporation was observed in the bronchi, bronchioles, and alveolar ducts for up to 21 NO2exposures. A significantly greater increase in [3H]thymidine incorporation was observed when the interval between subsequent exposures was extended to 7 days. However, no repeated exposure, whether at 2–3 or 7 day intervals, was as effective as the first NO2exposure in stimulating incorporation of [3H]thymidine.

ISSN:0098-4108    

DOI:10.1080/15287397709529515

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The host‐mediated assay and Salmonella/microsome test are reviewed and critically evaluated. Their methodological problems and relevance for humans are considered.

ISSN:0098-4108    

DOI:10.1080/15287397709529516

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor