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Biomedical subjects

L Young

Publications and source records attributed to L Young.

At least 307 records · Page 17Linked to original sources
PubMed1966

Biochemical studies of toxic agents. The metabolism of 1- and 2-bromopropane in rats.

1. (+)-n-Propylmercapturic acid sulphoxide, i.e. (+)-N-acetyl-S-n-propyl-l-cysteine S-oxide, was prepared as the dicyclohexylammonium salt, (-)-n-propyl-mercapturic acid sulphoxide was prepared as the free acid, and S-isopropyl-l-cysteine and isopropylmercapturic acid were also prepared. 2. The metabolism of 1- and 2-bromopropane was studied by radiochromatographic examination of the urine excreted by rats that had been fed with a diet containing (35)S-labelled yeast and then injected subcutaneously with these compounds. In addition to n-propyl-mercapturic acid and 2-hydroxypropylmercapturic acid, the excretion of which has already been reported, n-propylmercapturic acid sulphoxide was shown to be a metabolite of 1-bromopropane. Sulphur-containing metabolites of 2-bromopropane, if present in the urine at all, were there in very small amounts. 3. n-Propylmercapturic acid and isopropylmercapturic acid were isolated from the urine of rats that had been injected subcutaneously with S-n-propyl-l-cysteine and S-isopropyl-l-cysteine respectively.

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PubMedDate not supplied

Quantification of metastatic tumor growth in bleomycin-injured lungs.

The lung is a common target organ in experimental models of tumor metastasis in which quantification usually involves counting labeled tumor cells shortly after injection, or enumeration of grossly visible pleural tumors. In this study, these approaches were used in addition to autoradiographic and morphometric methods to analyse the effect of bleomycin-mediated injury on the development, distribution and quantification of pulmonary metastases. One day after intravenous injection of 2 X 10(5) fibrosarcoma cells, the lungs of C57 bl/6 mice, pretreated with bleomycin (120 mg/kg i.v., 5 days before) contained about nine times as many [131I] iododeoxyuridine-labeled cells as the lungs of control animals given saline injections. At this time, autoradiographic counts of [3H]thymidine-labeled tumor cells in lung sections showed a similar increase in tumor cell localization after bleomycin, with labeled cells distributed equally between parenchymal and pleural areas. However, subsequent tumor growth was demonstrated microscopically to be predominantly in pleural and peribronchial areas, especially at sites of lung injury induced by bleomycin. Counts of grossly visible pleural tumors failed to demonstrate a difference between bleomycin groups and controls at 7 days whereas counts of nodules in lung sections, and quantification of lung area occupied by tumor both showed significantly greater tumor involvement in bleomycin-treated animals. As tumors became confluent, morphometric measurements demonstrated tumor growth in the lung more accurately than did nodule counts. We conclude that bleomycin-induced injury greatly enhances metastatic tumor growth and that morphometric methods are more sensitive than lung colony counts in their ability to quantify pulmonary metastases. Morphometry and autoradiography have also demonstrated that while there is a uniform distribution of arrested tumor cells in the lung initially, there is preferential development of metastatic tumors at sites of pulmonary damage, in particular at the pleura.

Animals↗
PubMedDate not supplied

Preferential growth of metastatic tumors at the pleural surface of mouse lung.

In an experimental model of lung metastasis we have observed that more metastatic tumors are located on the pleura of the lung than in the parenchyma. To study possible reasons for this differential pattern we have now related the initial distribution of injected tumor cells to the later location and growth rate of metastases in different regions of the lung in C57bl/6 mice. It was found that labeled murine fibrosarcoma cells were evenly distributed throughout the lungs 24 h after intravenous injection into controls and animals previously treated with bleomycin or by exposure to hyperoxia. These treatments, known to induce pulmonary endothelial injury, were associated with increased tumor cell localization in the lung. In all cases, using morphometric methods, we found that after 2 weeks, approximately 75 per cent of metastatic tumors were located at the pleura. By [3H]thymidine labeling in autoradiographs, pleural tumors in all experimental groups had a growth rate 14 times the growth rate of tumors located in the internal regions of the lung. In vitro, the fibrosarcoma cells proliferated more rapidly on connective tissue matrices prepared from normal pleuras than they did on matrices from the remainder of the lung. Protease digestion of these matrices indicated differences in composition with more insoluble collagen, probably type I collagen, present at the pleura. These data suggest that, in spite of the initial random distribution and localization of tumor cells in the lung, there is preferential growth of metastatic tumors at the pleura which may be related to regional differences in the composition of the extracellular matrix.

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PubMedDate not supplied

Accidental envenoming by a Gaboon viper (Bitis gabonica): the haemostatic disturbances observed and investigation of in vitro haemostatic properties of whole venom.

We report the successful treatment of envenoming by the Gaboon viper (Bitis gabonica) and include results of in vitro investigations of the haemostatic properties of the whole venom. The patient was admitted to casualty soon after the bite with chest tightness, dizziness, nausea and swelling at the site of the bite and was treated immediately with polyspecific antivenom, hydrocortisone, chlorpheniramine and antibiotics. Results of haemostatic investigations were essentially normal on admission but on day 3 the thrombin time became prolonged and was associated with significant hypofibrinogenaemia and elevated D-dimers. Factors V and VIII, antithrombin III and protein C levels and platelet number were not significantly reduced. The haemostatic disturbances persisted for more than 24 h despite treatment with blood products (16 units of cryoprecipitate, 2 units of fresh frozen plasma and 6 units of platelet concentrate). Resolution of the abnormalities occurred only after administration of a further dose of antivenom. The period of hypofibrinogenaemia occurred at a time when venom antigen was undetectable in plasma by enzyme-linked immunosorbent assay. Studies in vitro with whole venom and a panel of amidolytic substrates commonly employed for measurement of haemostatic proteins revealed significant activity of venom with substrates sensitive to kallikrein and plasmin. The venom inhibited washed platelet aggregation induced by collagen, thrombin, arachidonic acid and the calcium ionophore A23187 in a dose-dependent manner.

Adult↗