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Biomedical subjects

J C Meunier

Publications and source records attributed to J C Meunier.

At least 145 records · Page 8Linked to original sources
PubMed1978

Kinetic studies of glyceraldehyde-3-phosphate dehydrogenase from rabbit muscle.

Initial rate studies at pH 7.6 with three aldehydes, product inhibition patterns with NADH and dead-end inhibition with adenosine diphosphoribose show that the kinetic mechanism of glyceraldehyde-3-phosphate dehydrogenase from rabbit muscle cannot be ordered, and support an enzyme-substitution mechanism. Deviations from Michaelis-Menten behaviour are consistent with negative interactions in the binding of NAD+ and instability of the species E(NAD)3 and E(NAD)4. Inhibition with large concentrations of phosphate and arsenate indicates competition for a binding site for glyceraldehyde 3-phosphate, and is not found with glyceraldehyde as substrate.

Adenosine Diphosphate Sugars↗
PubMed1978

Pituitary-testicular axis in diabetic men with and without sexual impotence.

In nine impotent diabetics (ID), eight diabetics with normal sexual function (ND), eight impotent non diabetics (IN) and seven normal patients (NN), we found normal basal FSH and LH levels. Plasma testosterone (T) values were significantly lower in ID and IN in comparison with NN and ND. After LHRH injection, plasma T increased in ID up to normal values. In non diabetic patients (NN and IN), LHRH induced a slight but significant rise in blood glucose. Post LHRH gonadotropins response was in the normal range for all groups and the amplitude of the response was highly correlated with basal levels except for LH in ND. Mean blood glucose during the test and LH response to LHRH were not inversely correlated in the patients studied. We conclude that impotence in diabetic patients is a neurological complication and that low testosterone levels are probably secondary to a decreased coital frequency. ID and IN probably share a common pattern of inadequate hypothalamic feedback control in the presence of low testosterone levels.

Adult↗
PubMed1977

Biochemical investigations of retinotectal specificity.

An in vitro assay for retinotectal specificity has been described. The results show that, in the chick embryo, cells dissociated from the dorsal retina preferentially adhered to ventral tectal surfaces while cells from the ventral retina preferentially adhered to dorsal tectal surfaces. These adhesive preferences thus mimic the retinotectal specificity observed in vivo. The assay has been extended for use with plasma membrane preparations from retinal cells. Experiments in which retinal cells or tectal surfaces were treated with purified proteases and glycosidases have partially characterized the moieties responsible for the observed specificities. These results are consistent with a double gradient in the dorsal-ventral axis of complementary proteins and carbohydrates. The carbohydrate moiety would be expected to terminate in an acetylated hexosamine and to be more concentrated dorsally in both retina and tectum. A protein that is complementary to the hexosamine terminus would be localized in the ventral part of retina and tectum.

Animals↗