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Biomedical subjects

J Guichard

Publications and source records attributed to J Guichard.

87 records · Page 5Linked to original sources
PubMed1972

Ultrastructural localization of peroxidase activity in human platelets and megakaryocytes.

Normal human platelets and megakaryocytes were examined for peroxidase activity by the diaminobenzidine (DAB) cytochemical technic. When the fixation and the incubation were adequate, a strong reaction was present in the dense tubular system of platelets suspended in plasma or spread on carbon. The black reaction product was ascribed to enzyme activity, since the reaction was completely eliminated when H(2)O(2) or DAB were omitted, or when H(2)O(2) was in excess. In addition, the reaction was inhibited by aminotriazole, cyanide and azide. In the human megakaryocytes, the reaction was localized in the endoplasmic reticulum including the perinuclear envelope. The Golgi complex and the clear vacuolar system were negative for the reaction. After platelet release, the reaction was always seen in the perinuclear space. The nature and function of the enzyme, as well as its possible relationships with catalase, are discussed.

Aniline Compounds↗
PubMedDate not supplied

Compared effects of morphine and nickel chloride on NK cell activity in vitro in rats and monkeys.

The measurement of natural killer (NK) cell activity often is recommended as an endpoint for inclusion in the non-clinical immunotoxicity evaluation of environmental chemicals and pharmaceuticals. To date, most data on the impact of immunotoxicants on NK cell activity have been obtained in the rat. Because non-human primates often are used in the safety evaluation of new medicinal products, there is a need to compare chemically induced changes in NK cell activity between rats and primates. In this study, the in vitro effects of nickel chloride and morphine hydrochloride were investigated on NK cell activity in the rat and the cynomolgus monkey. Despite some species-specific differences in the techniques used, rather similar results were obtained in the two species. At the higher concentration, nickel chloride induced a significant decrease in NK cell activity in the ranges of 21.6-24.3% (rat) and 34.4-42.2% (monkey), depending on the effector-to-target cell ratio used, and morphine hydrochloride induced a decrease in the ranges of 23.7-34.7% (rat) and 59.1-68.0% (monkey). These results suggest that NK cell activity can be used as a reliable endpoint for the assessment of immune effects during safety evaluation studies in the cynomolgus monkey.

Animals↗