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An isocratic high-performance liquid chromatographic (HPLC) system was developed for the separation of major phospholipid classes, i.e., phosphatidylcholine, sphingomyelin, lysophosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine. Phospholipids were detected with ultraviolet absorption at 205 nm and subsequent fluorescence detection. Fluorescence of the phospholipids (excitation, 340 nm; emission, 460 nm) was achieved by postcolumn formation of mixed micelles with 1,6-diphenyl-1,3,5-hexatriene. For ultraviolet absorption there were great differences depending on the saturation of phospholipid fatty acids but for fluorescence the sensitivity was almost identical for all phospholipids except phosphatidylinositol and lysophosphatidylcholine. Dipalmitoylphosphatidylcholine showed nearly no ultraviolet but good fluorescence response. Ultraviolet to fluorescence ratio was characteristic for different phospholipids and for identical phospholipids from different sources. Quantification of phosphatidylcholine and phosphatidylethanolamine with HPLC using N-monomethylphosphatidylethanolamine (dioleoyl) as an internal standard gave the same results as phospholipid phosphorus quantification after thin-layer chromatography.Copyright 1994, 1999 Academic Press, Inc.

Functional in vitro studies with isolated gastric mucosal cells require cytological identification of different cell types in suspension or primary culture. Since suitable techniques have not been well established, different staining methods for the discrimination of dispersed pig and guinea pig gastric cells have been developed on the basis of modified previous protocols for enzymatic cell dispersion. Chief and parietal cells were visualized by combined periodic acid-Schiff stains. Surface mucous and mucous neck cells were identified by affinity-labelling, using lectins with selective staining properties in situ. Two of the lectins were found to be specific markers for gastric polymorphonuclear cells. The following vital tests were found to be useful: succinic dehydrogenase for parietal cells, Nile blue/brilliant cresyl blue stains for chief cells, and different phagocytosis assays for endothelial cells and gastric phagocytes. Endocrine cells were characterized by immunocytochemistry using specific antibodies against gastrin, somatostatin, histamine and serotonin. The same technique using a vimentin antibody was performed for the identification of fibroblasts. Proliferation of mucosal cells in primary culture was monitored by the incorporation of bromo-deoxyuridine, which was subsequently detected by a monoclonal antibody.

WORK is now in progress at the University of Cape Town to determine the complete molecular structures of phenothiazine and of certain of its derivatives, chlorpromazine base1and stelazine. The last-mentioned two are well-known drugs, used as tranquillizers and in the treatment of certain mental diseases, such as schizophrenia, and it is hoped that knowledge of their molecular structure will help in the understanding of their biochemical action in man.