A method is described for the rapid isolation of a plasma membrane fraction containing a high concentration of intact bile canaliculi from the rat liver . Isolated bile canaliculi retain most of the ultrastructural features exhibited in the intact liver cell . The final fraction contains 5'-nucleotidase activity at approximately the same concentration as that in previous preparations of plasma membranes . In the presence of 0 .01 M Mg++, 5'-nucleotidase exhibits a double pH optimum at pH values of 7 .5 and 9 .5. The activities of glucose-6-phosphatase and alkaline phosphatase are present in low amounts . Cytochrome P-450 is not detectable . Na+-K+-activation of ATPase is observed to the extent of 20-36 0/, in about half of the assays. The availability of a method for preparation of intact bile canaliculi should prove useful for studying the biochemical events associated with the transport of bile constituents into canaliculi .

A B S T R A CT Polymorphonuclear neutrophils (PMN) from patients with chronic granulomatous disease of childhood have impaired bactericidal activity and are deficient in diphosphopyridine nucleotide, reduced form of, (NADH) oxidase. Since hydrocortisone had been shown to inhibit NADH oxidation, experiments were undertaken to determine the effect of hydrocortisone on several parameters of human PMN function.The phagocytic and bactericidal capacity of PMN with or without hydrocortisone (2.1 mM) was determined by quantitation of cell-free, cell-associated, and total bacteria. Phagocytosis of Staphylococcus autreus and several gram-negative rods was unimpaired by the presence of hydrocortisone in the media. In contrast, killing of bacteria was markedly impaired by hydrocortisone. After 30 min of incubation, there were 20-400 times as many bacteria surviving in hydrocortisone-treated PMN as in simultaneously run controls without hydrocortisone.The defect of intracellular killing noted in the presence of hydrocortisone was not related to impaired degranulation. Quantitative kinetic studies of degranulation revealed no difference in the release of granule associated acid phosphatase in hydrocortisone-treated and control PMN after phagocytosis. Electron microscopy of PMN also indicated that the presence of hydrocortisone had no effect on the extent of degranulation after phagocytosis. These observations were confirmed by studies using histochemical techniques to detect lysosomal enzymes.After phagocytosis, hydrocortisone-treated P.N demonstrated less NADH oxidase activity, oxygen consumption, and hydrogen peroxide production than postphagocytic control PMN. In addition, Nitro blue tetrazolium dye reduction was diminished in hydrocortisonetreated PMN.

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This study correlates the fine structure of mouse gastric endocrine cells with their ability to synthesize serotonin (5-HT) from 5-hydroxytryptophan (5-HTP) . Mice were sacrificed 2 hr after the intravenous injection of 5-HTP-3H or 5-HT-3H . Their stomachs were processed for light-and electron microscope radioautography in a manner which retained labeled 5-HT while washing out other labeled substances . Stomachs from additional mice were incubated in vitro with 5-HT-3H and processed similarly .All morphologic types of mouse gastric endocrine cells exhibited a similar facility to incorporate exogenous 5-HTP and to convert it to 5-HT which was bound intracellularly . Differences in densities of silver grains observed over endocrine cells suggested that individual endocrine cells indeed varied in their ability to synthesize and/or to bind 5-HT ; such variations, however, were not reflected by differences in fine structure, with the exception that endocrine cells with few granules always contained little newly synthesized 5-HT . The newly synthesized 5-HT was associated with the intracellular granules . The gastric endocrine cells were not labeled by exogenous 5-HT-3H, whereas mast cells were labeled by either 5-HT-3H or 5-HTP-3H administration . The findings of the present study support the position that the gastric endocrine cells represent a single cell type, at least in respect to serotonin metabolism-that the argyrophil or argentaffin reactivity of these cells merely reflects their amine content at a given time .

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