Biomedical subjects

W C Tan

Publications and source records attributed to W C Tan.

At least 127 records · Page 7Linked to original sources

PubMed1976

Liquid ion exchangers in reversed-phase systems for chromatography of steroidal glucosiduronic acids.

Steroidal glucosiduronic acids were chromatographed on paper by the reversed-phase technique using five different liquid ion exchangers as stationary phase and aqueous KCl as mobile phase. The relationship of mobility of the acids (Rm) to both the amount of exchanger on the paper and the concentration of KCl in the mobile phase is discussed: the relationships may be expressed as Rm=n.log [exchanger] + const. and RM=-N.LOG [KCl] + const., respectively. Migration of the acids in the presence of different exchangers is correlated by use of the equation Rm (exchanger Y)=a.Rm (exchanger X) + b. The lack of appreciable correlation between migration of the acids in a reversed-phase system and a corresponding straight-phase system is discussed and expressed by means of regression equations. The correlation coefficients and standard errors of estimate from these equations provide useful indices for selecting two solvent systems that are to be used sequentially to obtain maximal resolution of a group of compounds. deltaRm values obtained for various functional groups with reversed-phase and straight-phase techniques are compared.

Chromatography, Ion Exchange↗

PubMed1976

Toxic effects of hydroperoxide injections on rat lung. A light microscopical and ultrastructural study.

Intravenous administration of methyl linoleate hydroperoxide (MLH) uniformly resulted in extensive damage to septal wall components of the rat lung; the severity of these changes paralleled the administered dosage. The target cell of injury appeared to be the capillary endothelial cell. Destructive changes within the plasma membrane suggested that the major toxic effect of MLH was directed against membranous structures. Ultrastructural analysis showed that these effects were more severe in the vitamin E-deficient animals. Secondary changes were characterized by interstitial and alveolar edema, and degenerative changes within alveolar pneumocytes. Reparative proliferation of type 2 pneumocytes first became evident in animals that survived two days. These observations provide an insight into the susceptibility and sequential damage to pulmonary tissue by hydroperoxides and serve as a guide for investigations of the toxic effects of other oxidants on lung.

Animals↗

PubMed1975

Studies of lipid class and fatty acid profiles of rat mammary tumors induced by 7, 12-dimethylbenz(a)anthracene.

The lipid class and fatty acid composition profiles of mammary glands of female rats fed a nutritionally adequate diet are compared to those of tumors induced in the mammary glands by intravenous injection of dimethylbenz(a)anthracene of animals fed the same diet. Ca. 95% of the lipids of the mammary glands of the control group of animals consisted of triglycerides; glycolipids and phospholipids were present in only minor amounts. In contrast, the lipids of the mammary tumors contained much lower amounts of neutral lipids and higher concentrations of phospholipids. The glycolipid fraction was a minor component of both tissues but differed greatly in composition. The composition of the phospholipid and neutral lipid fractions, particulary the latter, of the mammary tumors also differed from that of the mammary glands of the control animals. The neutral lipids of the tumor tissues contained elevated levels of free fatty acids and cholesterol and much lower concentrations of triglyceride compared to the mammary gland lipids. Differences also were observed in the fatty acid composition of tumor and mammary gland lipid. The greatest differences occurred in the concentrations of polyunsaturated fatty acids which were generally much higher in the tumor lipids.

Animals↗

PubMed1974