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Biomedical subjects

S V Nizhnii

Publications and source records attributed to S V Nizhnii.

7 recordsLinked to original sources
PubMedDate not supplied

Investigation of the interaction of trypsin with heparin.

The reversible inhibition of the enzymatic activity of trypsin by heparin was investigated. On the basis of an analysis of the Lineweaver-Burk and Dixon graphs, a noncompetitive nature of the inhibition of the BAPA amidase activity of trypsin by heparin was detected, and the values of Km and Ki were determined, equal to 3.1 . 10(-4) and 3.7-3.9 . 10(-7) M, respectively. A comparison of these values indicates a great affinity of heparin for the enzyme. It was shown that heparin inhibits the BAEE esterase activity of trypsin and at the same time has no inhibiting effect on acetyltrypsin. Considering that the acetylation of trypsin leads to selective blocking of the epsilon-amino groups, it was concluded that the epsilon-amino groups of the lysine residues of the trypsin molecule participate in the interaction with heparin.

Catalysis↗
PubMedDate not supplied

Probability screening model.

A comparative analysis is given of various types of systems of selecting biologically active substances. A theoretical probability model of tests on chemical compounds for biological activity (screening) has been constructed which permits an evaluation of the efficacy of screening on the basis of fairly reasonable assumptions. It has been shown that this efficacy decreases in time with a fixed number of types of activity taken into consideration and rises sharply with an increase in the number of types of activity of chemical compounds taken into account in the tests.

Drug Evaluation, Preclinical↗
PubMedDate not supplied

The possibility of passive transport of histamine through biological membranes.

The possibility of transport of free and heparin-bound histamine along the concentration gradient through bimolecular lipid membranes (BLM) and the influence of various factors on it was studied. It was shown that histamine is capable of diffusing through BLM in the form of a singly charged cation. In contrast to histamine, neither heparin nor the histamine-heparin complex (HsHC) penetrates through BLM. It was established that the action of histamine-liberating factors -- increasing the ionic strength to 0.15 and the addition of trypsin to the solution -- on HsHC leads to the appearance of transport of histamine through the BLM as a result of an increase in the concentration of free histamine in solution.

Biological Transport↗
PubMedDate not supplied

Criteria for selection of physiologically active substances (pharmacometry under screening conditions).

The problem of quantitative evaluation of the pharmacological influence of physiologically active substances with receptor action on the organism under conditions of screening is discussed. A vector-significant criterion, based on a functional multiparameter method (FMM), is suggested as the basic characteristic of effectiveness of action. This criterion permits an evaluation of the latitude of the permissible physiological effect, the threshold of subtoxicity, and the selectivity of the action of the substance according to the dominant activity.

Animals↗
PubMedDate not supplied

Prostaglandins, steroids and reception (an attempt to model the structure of the active centers of adrenoreception).

On the basis of numerous results of investigations on adrenergic systems, an orientational model of the adrenoreceptor (AR) is postulated. Its active center includes low-molecular-weight components--prostaglandins (PGE, PGF), steroids (cortisone, hydrocortisone), S+-adenosylmethionine, Ca, Mg, and Mn ions. Appraisal of the stereospecific characteristics of such a functional unit of AR explains the difference in the nature and magnitude of the effects of interaction of the catecholamines, their agonists and antagonists will the so-called alpha- and beta-AR. Depending on the organ or tissue in which the AR is located, its protein subunits comprise adenylcyclase (beta-AR) or Na,K-ATPase (alpha-AR). An obligatory component of the AR is catechol-O-methyltransferase. The model elaborated describes satisfactorily the molecular mechanisms of action of many pharmacological agents, explains why attempts to isolate and reconstruct the AR have proved fruitless, and gives grounds for rejecting the hypothesis that there exist steroid, prostaglandin, and purinergic receptors, linking the exceptionally high and diverse activity of these biologically active substances with their participation in adrenoreception among other reasons. A conception of the active centers of the AR as low-molecular-weight entities permits the explanation of such phenomena as the desensitization of the AR, the "interconversion" of beta-AR into alpha-AR with a change in the parameters of the medium, and certain components of the pathogenesis of bronchial asthma, etc.

Adenosine Triphosphate↗
PubMedDate not supplied

Modes and classes of modes of action of physiologically active substances of receptor type under conditions of screening.

Questions of the identification of the type of pharmacological activity of physiologically active substances (PAS) with a receptor type of action under conditions of screening are examined. IN accordance with current concepts of the theory of the recognition of modes, the type of action of PAS was identified by establishing a set of criteria ("vectors of modes") characteristic of the effect of known substances and by selecting methods of comparing them with the vectors of the modes of the compounds being tested. Test parameters recorded by the the functional multiparametric method permitting identification of the type of the effects and an evaluation of their quantitative manifestations with the framework of a single experimental approach were used as the unknown set of criteria. The method of describing the relative change in the parameters from the dose as the vectors of action was used and the function of proximity (similarity).

Animals↗