Inhibition of integrin-mediated platelet aggregation, fibrinogen-binding, and interactions with extracellular matrix by nonpeptidic mimetics of Arg-Gly-Asp.

The interaction of the activated platelet integrin, glycoprotein IIb-IIIa (GPIIb-IIIa) with fibrinogen and von-Willebrand factor (vWF) is essential for platelet aggregation. The minimal structure required for this integrin's binding to fibrinogen is the Arg-Gly-Asp (RGD) sequence. Inasmuch as normal level of GPIIb-IIIa-RGD interactions are required for maintaining hemostasis, elevated platelet aggregation can cause adverse pathological effects. We have previously reported that nonpeptidic mimetics of RGD, consisting of carboxylate and guanidinium groups of Asp and Arg divided by a linear 11-atom spacer, acquired a significant affinity for the GPIIb-IIIa integrin and inhibited platelet aggregation. The structural requirements for the interactions of the RGD sequence with GPIIb-IIIa and the inhibitory potential of a newly designed series of mimetics on platelet aggregation and interactions with extracellular matrix (ECM) were assayed herein. Adenosine-diphosphate (ADP)-induced platelet aggregation was inhibited in a dose-dependent manner by various RGD mimetics, with a maximal inhibition of 80-100% with an IC50 of 3 microM for the most potent inhibitor, NS-11, in which a six-membered ring was introduced into the spacer chain, which exceeded the IC50 attained with the original RGDS peptide. The inhibitory effect of the RGD mimetics was attributed to their specific interaction with the GPIIb-IIIa integrin, since these mimetics inhibited the binding of the PAC-1 mAb to GPIIb-IIIA. Furthermore, the binding of 125I-labeled fibrinogen to platelets was inhibited by the RGD surrogates in a dose-dependent and saturable manner. The RGD-mimetics also inhibited up to 70% the adhesion, aggregation, and deposition of platelets onto ECM.(ABSTRACT TRUNCATED AT 250 WORDS)

[Combined helium-neon laser therapy in patients with ischemic heart disease]. / Kombinirovannaia gelii-neon-lazernaia terapiia u bol'nykh ishemicheskoi bolezn'iu serdtsa.

The paper describes the combined helium-neon-laser (HNL) therapy (intravenous and topical) developed by the authors to treat patients with coronary heart disease. A high efficacy of this therapy mode was demonstrated in patients over 70 years of age with Functional Classes III-IV angina refractory to antianginal agents. The mechanisms responsible for therapeutic efficiency of laser irradiation were studied at the membraneous and cellular levels. There is evidence that the combined HNL-therapy had advantages over topical HNL exposure in terms of higher clinical efficiency and patterns of abnormal chemical changes.

[Clinico-pathochemical substantiation of the exacerbation phenomenon in patients with ischemic heart disease during treatment with the helium-neon laser]. / Kliniko-patokhimicheskoe obosnovanie fenomena obostreniia u bol'nykh ishemicheskoi bolezn'iu serdtsa pri lechenii gelii-neonovym lazerom.

Some pathochemical mechanisms of coronary disease aggravation in the course of laser therapy were assessed by means of the measurement of erythrocyte membrane lipids and phospholipids as well as plasma alpha-tocopherol and diene conjugate levels. The aggravation was associated with an activation of metabolic processes aiming to produce regeneration of membrane structures. The regeneration takes place in the presence of chronic deficiency of total phospholipids and inadequate antioxidant protection of biomembranes, therefore complete stabilization and normalization of their composition and activity is impossible.

[Metabolism of several blood prostaglandins in patients with angina pectoris during helium-neon laser therapy]. / Metabolizm nekotorykh prostaglandinov krovi u bol'nykh so stenokardiei na fone gelii-neonovoi lazernoi terapii.

The paper shows the high therapeutical efficiency of combined He-Ne laser therapy in patients with coronary heart disease. Its effect on the thromboxane-prostacyclin system is one of the mechanisms of laser impact. The combined He-Ne laser therapy promotes normalization of the level of thromboxane B2 and its ratio to the metabolite prostacyclin.

[Clinico-biochemical parallels against a background of traditional treatment and laser therapy of patients with ischemic heart disease]. / Kliniko-biokhimicheskie paralleli na fone traditsionnogo lecheniia i lazeroterapii bol'nykh ishemicheskoi bolezn'iu serdtsa.

The paper is devoted to analysis of clinico-biochemical indices and a quest for additional pathologico-chemical criteria at the cell membrane level of the efficacy of helium-neon laser therapy in coronary heart disease (CHD). Another task was to decipher a number of metabolic signs of the phenomenon of CHD "exacerbation" in laser therapy (during 4-6 sessions). Positive clinical results were obtained in 98% of the patients. A favorable time course was noted in serum lipoprotein spectrum indices and in lipid and phospholipid structure of erythrocyte membranes. Laser therapy caused mobilization of the cell membrane antioxidant defense. The 4th-6th session of irradiation was marked by temporary clinical deterioration--"exacerbation" of disease accompanied by an increase in the level of erythrocyte total phospholipids (at the expense of PTEA), a decrease in free fatty acid deficiency against a background of advancing alpha-tocopherol deficiency and a rise of the blood level of lipid peroxidation primary products (diene conjugates). A conclusion was that membrane protective drugs and drugs enhancing cell energy and antioxidant defense resources promoting the "deactivation" of influence on the membrane of lipid peroxidation metabolites (tocopherol, Essentiale, retinol, etc.) should be incorporated in therapy of CHD in order to prevent the phenomenon of its "exacerbation".

[Prevention of the "secondary exacerbation" phenomenon in patients with stenocardia treated with helium-neon laser therapy]. / Profilaktika fenomena "vtorichnogo obostreniia" u bol'nykh stenokardiei pri gelii-neon-lazernoi terapii.

The authors have developed a method for the prevention of angina pectoris "'secondary exacerbation' developing during He-Ne laser irradiation of the Zakharyin-Head skin sites. Intake of aevit (a multivitamin preparation) in a daily dose of 600 mg allows increasing the length of exposure to He-Ne laser in the most grave coronary cases and prolongs the remission. A rationale for He-Ne laser therapy efficacy combined with aevit is given.

[Helium-neon laser therapy in the combined treatment of unstable stenocardia]. / Gelii-neonovaia lazernaia terapiia v kompleksnom lechenii nestabil'noi stenokardii.

He-Ne laser therapy included in complex of therapeutic methods for patients with unstable angina pectoris is a highly effective treatment modality; it helps essentially reduce the risk of acute myocardial infarction in these patients. Clinical efficacy of laser therapy is confirmed by its favorable action on hemostasis plasma factors, consisting in reduction of fibrinogen level, normalization of antithrombin-III (AT-III), decrease of the level of soluble fibrinomonomer complexes, this indicating a lowering of the blood coagulation potential. Absence of significant changes in plasminogen level may be an indicator of the nonenzymic route of fibrinogen system activation. Sessions of intravenous laser therapy should be administered 2-3 times a week to unstable angina pectoris patients with low AT-III levels, whereas for patients with initially high or normal AT-III levels combined laser therapy is advisable (4-5 daily invasive procedures and 6-8 skin surface ones on the Zakharyin-Head's zones). Measurements of endogenic anticoagulants is an effective means for monitoring laser therapy in this patient population.

Inhibition of CD4+ T lymphocyte binding to fibronectin and immune-cell accumulation in inflammatory sites by non-peptidic mimetics of Arg-Gly-Asp.

The Arg-Gly-Asp (RGD) cell adhesion motif has been demonstrated in various studies to play a pivotal role in leucocyte and platelet interactions with plasma and extracellular matrix (ECM) glycoproteins. The recognition of the RGD sequence is mediated by heterodimeric receptors designated integrins of the beta 1 subfamily, expressed on distinct cell types, including T lymphocytes. We have recently shown that flexible non-peptidic mimetics of RGD, in which the two ionic side groups were separated by a linear spacer of 11 atoms, bound specifically to the platelet integrin alpha 11b beta 3, and inhibited T cell-mediated immune responses. The present study was designed to (i) further characterize the structural requirements for RGD interactions with CD4+ T cells, and (ii) examine the mechanisms by which the RGD mimetics interfere with immune cell reactivity in vivo. We now report that freezing the conformational degrees of freedom in the spacer chain, which fixes the relative orientation of the guanidinium and carboxylate side groups in a favourable manner, results in a higher level of inhibition of T cell binding to immobilized fibronectin, an RGD-containing ECM glycoprotein. In vivo, treatment of mice with relatively low doses of the RGD mimetics, but not the RGD peptide, inhibited the elicitation of an adoptively transferred DTH reaction. This inhibition was achieved by direct impairment of the ability of antigen-primed lymph node cells to migrate and accumulate in inflammatory sites. Hence, we suggest that the design and production of non-peptidic mimetics of RGD offers a novel approach to study defined parameters related to the structure-function requirements of small adhesion epitopes. Furthermore, this approach could be used therapeutically to inhibit pathological processes which depend on RGD recognition.

[Intravenous laser therapy in multimodal treatment of acute pneumonia]. / Vnutrivennaia lazeroterapiia v kompleksnom lechenii ostrykh pnevmonii.

Such therapy has been administered to 70 patients with acute pneumonias. 25 patients on traditional therapy have made up the reference group. The effects of laser therapy on the clinical picture, status of the coagulation system cellular and plasma factors, fibrinolysis, and on the blood stream at the site of the pneumonic involvement have been examined in the patients with acute pneumonias in single tests and after a course of treatment. Intravenous laser therapy has had a favourable effect on the clinical course of acute pneumonias, accelerating the terms of pneumonia resolution and promoting and earlier and more complete restoration of the blood stream and normalization of the hemostasis, in contrast to routine therapy.

Structural analysis of integrin recognition and the inhibition of integrin-mediated cell functions by novel nonpeptidic surrogates of the Arg-Gly-Asp sequence.

The pivotal role of the Arg-Gly-Asp (RGD) peptide motif in integrin-mediated cell adhesive interactions with extracellular matrix and plasma proteins stimulated the present design of nonpeptidic mimetics of this sequence. To probe the structural requirements for RGD recognition by integrins, we designed various structural mimetics of the tripeptide sequence, which consist of differentially spaced guanidinium and carboxylic groups. We now report that structures which contain guanidinium and carboxylic groups separated by an 11-carbon atom backbone mimic the distal configuration of functional RGD sequence. These compounds acquire a considerable affinity for the RGD-dependent platelet alpha IIb beta 3 integrin. As a result, these mimetics specifically inhibited platelet aggregation with an IC50 at the submillimolar range and interfered with RGD-dependent adhesion of CD4+ T-lymphocytes and metastatic tumor cells to immobilized fibronectin and vitronectin. A structural mimetic of the Arg-Gly-Glu (RGE) sequence, and structures with incorrect spacing between the functional groups, failed to inhibit these adhesive interactions. Furthermore, substitution of the guanidinium group by a primary amine abrogated the RGD-mediated biological effects. In vivo, an RGD surrogate effectively inhibited the elicitation of a delayed-type hypersensitivity reaction mediated by CD4+ T-cells, while the RGE mimetic did not. This interference suggests for a central role for RGD recognition in the regulation of immune responses. These proteolytically stable RGD mimetics may thus serve as useful therapeutic agents in versatile pathologic processes which depend on RGD recognition.

[Effects of low-intensity laser irradiation on the functional activity of leukocytes and blood antioxidant system in acute myocardial infarction]. / Vliianie nizkointensivnogo lazernogo izlucheniia na funktsional'nuiu aktivnost' leikotsitov i antioksidantnuiu sistemu plazmy krovi pri ostrom infarkte miokarda.

Activation of lipid peroxidation and inadequate antioxidant activity essentially contribute to the pathogenesis of acute myocardial infarction, this fact dictating the necessity of correcting these processes. High efficacy of of He-Ne laser therapy was demonstrated in the treatment of 92 patients with myocardial infarction in the acute and subacute periods. This treatment modality corrected lipid peroxidation parameters, which fact manifested by reduction of leukocytic functional activity and elevation of blood plasma antioxidant characteristics.