[Activa tion of the complement system by the classical and alternative pathways in prolonged type 2 diabetes mellitus].

The study was undertaken to assess the functional activity of the classical and alternative pathways of complement activation in type 2 diabetes mellitus (DM-2) at late stages of the disease. For this purpose, the total hemolytic activity of the classical and alternative pathways of complement activation and the hemolytic activities of the complement components C1, C2, C3, and C4 were determined in the blood of patients with DM-2 and healthy individuals. According to the data obtained, patients with DM-2 at late stages of the disease have statistically significant increases in both the total hemolylical activity of the classical pathway of complement activation (by 1.5 times; p < 0 01; t = 2.54) and the hemolytic activities of individual complement components - C1 and C3 by 2.2 times (t - 2.05;p < 0 046 and t = 3.9; p < 0 0004, respectively) and C4 by 1.8 times (t - 2.05; p < 0.046) whereas the total hemolytic activity of the alternative pathway and the hemolytic activity of the complement component C2 remain in the normal range (p > 0 5). The findings suggest that the alternative pathway of complement activation is most likely to make no contribution to the activation of C3-convertase and the subsequent generation of C3d, and the further formation of the cytolytic and membrane-attacking complex.

Interaction of dopamine-beta-monooxygenase with lipids: 1. Lipids as modulators of the catalytic activity of the enzyme.

The interaction of the membrane-bound and soluble forms of dopamine-beta-monooxygenase with a variety of lipid analogues of the membrane of chromaffin granules were studied. The use of two independent methods to determine the kinetics of product formation and of oxidation of the electron donor substrates (two substrates, dopamine and tyramine, and two electron donors, ascorbate and ferrocyanide), showed that the enzyme is activated in the presence of either phosphatidylcholine or lysophosphatidylcholine, but is inhibited by phosphatidylserine, phosphatidylethanolamine, and phosphatidic acid. The magnitude of the effects observed was the same for both forms of the enzyme. The parameters Vmax and Km for the substrates and for the electron donors were determined in the presence of each of the lipids tested. The data lead to certain conclusions about the mechanism of action of the lipids upon the enzyme and about the possible physiological role of the effects observed.