[Kallikrein-kinin system as a target for diabetic retinopathy treatment].

Multifactor etiology of diabetic retinopathy (DR) determines difficulty of understanding of pathogenesis and need of search of effective approaches to study key mechanisms of development of this microvascular complication of diabetes mellitus (DM). Significant achievements of the last years show the contribution of two proteolytic systems into pathogenesis of DR, that control vascular tone and permeability - kallikrein-kinin (KKS) and renin-angiotensin systems (RAS). Among new approaches to DR treatment one of the most appropriate is an influence on KKS by means of inhibiting kallikrein, that leads to reduction of retinal vascular permeability and allows to prevent the development of macula oedema and other consequences of vascular wall damage in DR.

Contact system. New concepts on activation mechanisms and bioregulatory functions.

This review considers the data of recent years concerning the contact system initiating the activation of blood plasma proteolytic systems, such as hemocoagulation, fibrinolysis, kininogenesis, and also complement and angiotensinogenesis. The main proteins of the contact system are the factors XII and XI, prekallikrein, and high-molecular-weight kininogen. The data on the structure, functions, and biosynthesis of these proteins and on their genes are presented. Studies in detail on the protein-protein interactions during formation of the ensemble of the contact system components on the anionic surface resulted in the postulation of the mechanism of activation of this system associated with generation of the XIIa factor and of kallikrein. This mechanism is traditionally considered a trigger of processes for the internal pathway of the hemocoagulating cascade. However, the absence of direct confirmation of such activation in vivo and the absence of hemorrhagia in the deficiency of these components stimulated the studies designed to find another mechanism of their activation and physiological role outside of the hemostasis system. As a result, a new concept on the contact system activation on the endothelial cell membrane was proposed. This concept is based on the isolation of a complex of proteins, which in addition to the above-mentioned proteins includes cytokeratin 1 and the receptors of the urokinase-like plasminogen activator and of the complement q-component. The ideas on the role of this system in the biology of vessels are developed. Some of our findings on the effect of leukocytic elastase on the key components of the contact system are also presented.

[Isolation, purification, and properties of factor XII and its active fragment (beta-XIIa)]. / Poluchenie, ochistka, svoistva faktora XII i ego aktivnogo fragmenta (beta-XIIa).

A procedure of isolation of human blood plasma prekallikrein, coagulation factor XII and active fragment beta-XIIa has been developed. This procedure includes the traditional chromatography steps and FPLC. Disc-electrophoresis revealed that the preparations of factor XII and beta-XIIa were homogeneous. Their specific activity was 70.6 U and 2.5 U, respectively. The procedure described is less time consuming and it allows to isolate these factors in the preparative quantities.

[The effect of leukocyte elastase on high molecular weight kininogen from human plasma in the presence of alpha-1 protease inhibitor. Analysis of proteolytic degradation]. / Deistvie leikotsitarnoi élastazy na vysokomolekuliarnyi kininogen plazmy krovi cheloveka v prisutstvii al'fa-1-proteinaznogo ingibitora. Analiz proteoliticheskoi degradatsii.

Degranulation of polymorphonuclear leukocytes (neutrophils) and releasing of leukocyte elastase during inflammation occur not only in injured tissue but in plasma in the presence of considerable excess of alpha-1 proteinase inhibitor (alpha-1PI). However, in spite of the absence of free elastase in patients' plasma, even in such severe inflammation as peritonitis and septicaemia, degradation of the connective tissue structures and plasma proteins may be determined. However the reasons of such destructive action are not yet determined. In this paper the action of leukocyte elastase on human plasma high molecular weight kininogen (HMWK) was studied in the absence or in the presence of different concentrations of alpha-1PI. The results showed that degradation of the intact molecules of HMWK occurred under the action of elastase during 1-2 hours of combined incubation even if the concentration of alpha-1PI in the mixture in 3-5 fold exceeds the molar elastase concentration. The rate of elastase inhibition by alpha-1PI in the presence of HMWK did not depend on an order of enzyme and inhibitor addition to the incubation medium. HMWK degradation by elastase in the presence of alpha-1PI was accompanied by impairments in its adhesion function although high tolerance of HMWK inhibitory activity with respect to SH-proteinases preserved. Thus, total inhibition of leukocyte elastase by alpha-1PI, in the presence of high molecular weight kininogen develops during relatively long time interval. The pronounced destruction of intact HMWK molecules takes place during this period of gradual elastase inhibition. This fact seems to be very important in pathogenesis of thrombo-haemorrhage syndrome as a complication of severe inflammation.