Guo-Zhi Jiang

Localization of Apoptosis (Programmed Cell Death) in Mice by Administration of Lipopolysaccharide

Localization of apoptotic cells by administration of lipopolysaccharide into mice was studied by using the in situ specific labeling of fragmented DNA. This method clearly stained the nuclei of thymocytes at the cortex of the thymus. The nuclei of cells in the bone marrow and in the spleen were also positively stained. It was suggested that the cortex in the thymus is where the LPS‐induced programmed cell death occurs.

Increased Phosphodiesters in Lipopolysaccharide Prepared from the Polymyxin B-Resistant Isolate of Klebsiella pneumoniae

A polymyxin B (PXB)‐resistant mutant of Klebsiella pneumoniae O3 was isolated. Lipopolysaccharide (LPS) extracted from the PXB‐resistant isolate bound little PXB, although LPS from the parental strain did. The 31P nuclear magnetic resonance (NMR) spectrum of PXB‐resistant type LPS showed that it contained much less of the phosphomonoesters and the pyrophosphate esters, and an increased amount of the phosphodiesters, compared to the parental type LPS. The decrease in the binding of PXB might be due to altered phosphate groups on the PXB‐resistant type LPS, suggesting that it might explain the PXB‐resistance of the mutant.