摘要:

Fly ash from a fluidized‐bed coal combustor was neutron‐activated and administered to male Fischer 344 rats by a single nose‐only inhalation exposure. The activated fly ash contained46Sc and smaller amounts of other gamma‐emitting radionuclides. Whole‐body clearance of radioactivity to 127 d was described by an exponential equation, with the long‐term component having a biological half‐life of 78 d. High‐resolution gamma spectra of the lungs were obtained with a Ge(Li) detector and the relative activities of several fly ash constituents were compared. The activities of152Eu,134Cs,54Mn, and60Co significantly decreased with time relative to those of46Sc and59Fe. These results indicate that the clearance of fly ash is similar to that of other relatively insoluble particles and that some elements may have been preferentially dissolved from the fly ash particlesin vivo.

ISSN:0098-4108    

DOI:10.1080/15287398109529963

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Heating of fats brings about measurable changes in their chemical and physical characteristics. Heat is applied in processing for food manufacture, such as during hydrogenation of oils with a catalyst, and in frying for meal preparation. Partially hydrogenated products generally contain substantial quantities of geometric and positional isomers of the original unsaturated fatty acids. During deep‐fat frying, when the fat is used repeatedly, oxidative and thermal effects result in the formation of many volatile and nonvolatile products, some of which are potentially toxic, depending on the level of intake. Because of concern about the types of changes that take place in fats during oxidative and thermal deterioration and the effects the derivatives could have on the consumer, many chemical and biological studies have been carried out. Experimental findings indicate that any potential danger to the consumer is relative to the severity of the overall treatment of the fat. In some studies we evaluated biological effects on rats of trans fatty acid In the diet and of concentrates of fatty acid derivatives produced in thermally oxidized fats.trans‐Octadecenoic acid changed the concentrations of the phospholipid classes in the liver lipids, and interfered with conversion of the essentialn— 6 series of fatty acids to higher members. Compared to oleic acid, elaidic acid was preferentially incorporated into the phospholipids instead of the triacylglycerols and was also concentrated in the liproprotein fractions. Administration of non‐urea‐adductable concentrates from thermally oxidized fats produced cellular damage in the hearts, livers, and kidneys of the animals. Since even practical processing and frying conditions can produce some nutritionally undesirable products, a concerted effort should be made to minimize substantial accumulation of these in our dietary fats.

ISSN:0098-4108    

DOI:10.1080/15287398109529964

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Various mechanisms, including increases in lipid peroxidation, have been proposed to account for metal‐induced cellular injury. By comparing several metals in the same cell population, it is possible to determine whether a correlation exists between ability to produce cell injury and ability to alter parameters pertaining to a particular mechanism. Of particular interest in this study was the relation between metal‐induced cytotoxicity and increases in lipid peroxidation. The effects of Cr, Mn, Zn, Ni, Pb, Se, V, Fe, Cd, Hg, and Cu, at final concentrations of 1–1000 μM, on the viability of isolated hepatocytes were therefore examined by assessing the loss of intraceliuiar K+and aspartate aminotransferase (AST). Simultaneously, the ability of the metals to induce lipid peroxidation, as measured by an increase in thiobarbituric acid (TBA) reactants, was assessed. Hg and Cu required the lowest concentration to produce cellular injury, while Cd produced less dramatic changes in cell viability and Fe at 1000 μM produced only a small decrease in intraceliuiar K+. The largest absolute increases in lipid peroxidation were found in the presence of V, followed by Fe and Hg, with Cd and Se causing the smallest increase in TBA reactants. These observations suggest that the lipid peroxidation associated with Cd and Hg is not necessarily responsible for the loss of cell viability induced by these two metals.

ISSN:0098-4108    

DOI:10.1080/15287398109529965

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Interactions between Cd and other metal ions are important from both nutritional and toxicological aspects. As Cd is toxic to isolated hepatocytes, these cells can be used to investigate the effects of other metals on Cd‐induced cellular injury. Isolated hepatocytes were incubated at 37°C with vehicle (saline); Cd (200 or 400 μM); or Cd plus Cr, Mn, Zn, Ni, Pb, Se, or Fe (200–1000 μM). Evidence of cellular injury was assessed by loss of Intracellular K+and aspartate aminotransferase from the hepatocytes. Effects on lipid peroxidation, as measured by concentration of thiobarbituric acid reactants, were assessed. Uptake of109Cd and interaction of the other metal ions with this accumulation were also quantitated. Cell injury due to Cd was consistently reduced by Cr, Mn, Zn, Pb, and Fe. Lipid peroxidation due to Cd was inhibited by Cr, Mn, and Zn. All the metals except Ni produced an increase in the amount of Cd accumulated by hepatocytes. There was no consistent relation between reduction of cellular toxicity and either inhibition of lipid peroxidation or uptake of Cd. These experiments show that (1) protective properties of some metals seenin vivocan be demonstrated at the cellular level and (2) protective effects of metals in general on Cd‐induced cellular toxicity are not due to a decrease in either Cd uptake or lipid peroxidation.

ISSN:0098-4108    

DOI:10.1080/15287398109529966

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A high proportion of human mammary cancers contain a measurable amount of estrogen receptors. The presence of estrogen receptors correlates well with the response of patients to endocrine therapy, but not with their response to chemotherapy. However, receptor‐mediated chemotherapy should result in more selective and efficient treatment of receptor‐positive tumors. Several agents containing an estrogenic and a cytotoxic moiety have been synthesized in the past. It is not surprising that the affinity of these compounds for the estradioi receptor is very low, since most of them were synthesized before our knowledge of hormone receptor mechanisms.

ISSN:0098-4108    

DOI:10.1080/15287398109529967

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0098-4108    

DOI:10.1080/15287398109529968

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0098-4108    

DOI:10.1080/15287398109529952

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor