The effect of neighboring 1- and 2-adamantyl group substitution on the conformations and stereodynamics of N-methylpiperidine. Dynamic NMR spectroscopy and molecular mechanics calculations.

When a 1-adamantyl or a 2-adamantyl substituent is introduced at the 2-position in N-methylpiperidine, four different chair conformations are possible. Experimental observation using dynamic NMR spectroscopy and molecular mechanics calculations agree that the chair conformation with an equatorial adamantyl group and an axial methyl group is by far the most stable, but in both cases a minor population of a second conformation is demonstrated and characterized. Interaction between adamantyl and methyl groups is much more conformation-determining than any preference for equatorial over axial location which predominates in simpler 2-substituted N-methylpiperidines.

Report of three cases of circulating heparin-like anticoagulants.

Clinically significant endogenous circulating heparin-like anticoagulant activity has been associated with hematological malignancies, liver damage, and other pathological conditions. The source of high plasma concentrations of endogenous heparin-like anticoagulants is poorly understood. We report three cases of circulating heparin-like anticoagulants in three patients with hematological malignancies: CLL, multiple myeloma, and T-prolymphocytic leukemia.

[Prevalence of Factor V Leiden and the G20210A mutation of the prothrombin gene in a random group of patients with thrombotic episodes].

Unlabelled: Factor V Leiden and G20210A mutation of the prothrombin gene have been described as risk factors in thrombophilic pathologies. Our objective has been to know the prevalence of these two mutations in a group of patients with thrombophilic pathology and to compare it with its prevalence in a control group of Spanish population.

Patients And Methods: 64 patients were divided in two groups.