Analysis of the influence of Piyavit®—a biologically active compound of natural origin—on conditioned memory,on neuron-glia interactions of hippocampus,and on neocortex of rat brain

Mnemotropic effect of Piyavit®-a biologically active compound of natural origin—was studied on conditioned avoidance in rats. Morphological changes in neocortex and hippocampus (neuron-glia complex and brain capillaries) were significant and oppositely oriented. We assume that the improvement of rats’ memory under the Piyavitis associated with metabolic changes in the nervous tissues.     

Antithrombotic effect of preparations from the leeches Hirudo medicinalis

Antithrombotic effect of leech salivary gland secretion was maximal after intravenous administration into rats and was slightly decreased in cases of peroral administration. Blood from leech intestinal tract and leech homogenate exhibited less distinct antithrombotic action. Effect of these preparations was maintained after peroral administration. The antithrombotic effect of the leech preparations did not depend on their antithrombic activity caused by hirudin. These leech preparations appear to elongate a period of blood plasma recalcification caused by kallikrein inhibitor as well as apparently due to their capacity to inhibit aggregation of the thrombocytes.     

Prothrombin--substrate for blood plasma kallikrein and factor XIIa

A study was made of the interaction between prothrombin and enzymes: blood plasma kallikrein and factors alpha-XIIa and beta-XIIa immobilized on enzacryl-AH. Kallikrein-induced prothrombin proteolysis was accompanied by a decrease in prothrombin activity, appearance of BAME-esterase and poor clotting activity. As a result of fractionation of products on the column with DEAE-Sephadex A-50, some fractions that have thrombin amidase activity (splitting of the substrate S-2238) and high antithrombin activity were obtained. Antithrombin activity manifested in the inhibition of fibrinmonomer aggregation during fibrin formation. During incubation with prothrombin, factors alpha-XIIa and beta-XIIa also stimulated the appearance of BAME-esterase activity. None of the immobilized enzymes activated factor X.     

Monomerization of the fragment D dimer of stabilized fibrin by a secretion from the medicinal leech salivary gland]

The salivary gland secretion of the medicinal leech catalyzes the conversion into monomeric form of the fragment D dimer, the product of limited proteolysis of stabilized fibrin. Analysis of N-terminal sequences revealed identical fragments for the D-dimer gamma-gamma-chains and the D-monomer gamma-chains formed via this reaction and established the presence of only one N-terminal amino acid (Ser). These results provide evidence for the preservation of integrity of the polypeptide chains during monomerization of the D-dimer.