Inhibitory effect of sulfonylureas on protein phosphatase activity in rat pancreatic islets.

We have measured protein phosphatase (PP) activity in crude homogenates as well as in the total 105.000 x g supernatant and precipitate fractions from normal rat pancreatic islets. On the basis of the inhibition produced by either 1 nM or 1 microM okadaic acid, both PP1 and PP2A activity were present in crude islet homogenates in equivalent proportions (53% and 47%, respectively); PP1 was the main activity present in the precipitate, whereas in the supernatant it was PP2A. Tolbutamide, glybenclamide and glyclazide significantly decreased PP activity in islet homogenates in a dose-dependent manner, with a K10.5 value that in the case of glybenclamide correlated with its Kd for binding site, its EC50 on KATP channel, and its EC50 on insulin release. These data indicate that PPs play a role in the control of insulin secretion and suggest a further possible target for sulfonylureas within their overall action as insulin secretagogues.

Anthropological survey on north Cameroon peopling: I. GC subtyping (with a brief overview on the GC distribution in sub-Saharan Africa).

Group-specific component (GC) polymorphism was investigated in 1324 subjects belonging to 12 ethnic groups from North Cameroon including Daba, Fali, Fulbe, Kanuri, Mada, Mafa, Mandara, Mundang, Uldeme, Podokwo, Tali, and Tupuri. The GC*1F frequency ranged from 0.785 among Fulbe to 0.847 among Mundang, that of GC*1S from 0.071 among Mafa to 0.125 among Fulbe and that of GC*2 from 0.035 among Uldeme to 0.092 among Tupuri. The results obtained are discussed in the light of the knowledge about the distribution and the possible selective relevance of GC polymorphism.