Lipid peroxides and thrombosis

On incubation of rabbit platelets with ADP, adrenalin, serotonin, and thrombin, the level of lipid hydroperoxides in the platelets, determined as malonic dialdehyde, increases parallel with the increased aggregative power. An even higher concentration of malonic dialdehyde is observed in the platelets of animals with pulmonary thrombosis. Dynamic studies showed that the accumulation of malonic dialdehydes in the platelets reflects the initial stage of development of thrombosis; this can be used for the diagnosis of the early stages of intravascular thrombosis.Laboratory of Pathophysiology, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 5, pp. 414–417, May, 1979.     

Mechanism of action of aspirin on platelet function

Inhibition of platelet aggregation and of the reaction of liberation of platelet factor 3 under the influence of aspirin was shown to be due to the action of the drug not only on the platelets, but also on plasma cofactors: In experimentsin vitro the blood plasma of rats receiving aspirin reduced the aggregating power of the platelets of intact animals; blood plasma of intact rats increased the aggregating power and accessibility of factor 3 of the platelets of animals receiving aspirin.Department of Radiation Pathological Physiology, Scientific-Research Institute of Medical Radiology, Academy of Medical Sciences of the USSR, Obninsk. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Fedorov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 434–435, April, 1977.     

Difference between mechanisms of changes in platelet and erythrocyte aggregation in renal failure

Aggregation reactions of platelets and erythrocytes were studied in chronic renal failure. Differences in the mechanism of aggregation of platelets and erythrocytes are discussed on the basis of data showing opposite changes in the aggregation function of cells of the same subjects under similar conditions.Laboratory of Physiology of the Circulation, I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR. Department of Field Medicine, S. M. Kirov Military Medical Academy, Leningrad. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Chernigovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 3, pp. 263–265, March, 1980.     

Synthetic polycations as activators of the endogenous mechanism of platelet aggregation

Synthetic nitrogenous cationic polymers possess the ability to aggregate platelets in citrated plasma in a concentration of 1.5–10 g/ml. The action of polycations on platelets leading to their aggregation is brought about, if the cells are in a functionally active state, through activation of the endogenous aggregation mechanism.Scientific-Research Institute of Medical Radiology, Academy of Medical Sciences of the USSR, Obninsk. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Fedorov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 5, pp. 532–534, May, 1977.     

Cytotoxic activity of peripheral blood platelets and mononuclears in cancer patients and healthy donors

The cytotoxic activity of peripheral blood platelets and mononuclears from 82 patients with cancer, 9 with diseases other than cancer, and 18 healthy donors towards a continuous cell line of pulmonary adenocarcinoma was studied. There were no appreciable differences in the killer activity of platelets in cancer patients (32±3.5%), patients with diseases other than cancer (33±8.1%), and healthy donors (30±6.7%). In contrast to platelets, mononuclears of cancer patients possessed a higher cytotoxicity than mononuclears of healthy donors. The cytotoxicity of platelets of cancer patients was found to reliably drop in cases with disseminated metastases and after polychemo-and radiotherapy. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 2, pp. 192–195, February, 1996 Presented by N. N. Trapeznikov, Member of the Russian Academy of Medical Sciences     

Cholesterol biosynthesis in the blood of rabbits with experimental atherosclerosis

Blood of normal rabbits and of rabbits on an atherogenic high-cholesterol diet was incubated with sodium acetate-2-[¹⁴C]. After incubation, cholesterol and its precursors (squalene and lanosterol) were found and identified in the unsaponified fractions of leukocytes and platelets. Both in normal rabbits and in rabbits with atherosclerosis the highest specific activity in the leukocytes was found in cholesterol, followed by lanosterol and squalene; in the platelets the label accumulated mainly in lanosterol.A. V. Palladin Institute of Biochemistry, Academy of Sciences of the Ukrainian SSR. Institute of Gerontology, Academy of Medical Sciences of the USSR, Kiev. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Gorev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 12, pp. 689–691, December, 1978.     

Effect of bradykinin on platelet aggregation

The effect of bradykinin on ADP-induced aggregation of blood platelets was investigated in rabbits. Bradykinin reduced the degree of aggregation; maximal inhibition of aggregation was observed with the use of bradykinin in a concentration of 10–100 ng/ml. Higher concentrations of bradykinin were less effective. An essential condition for inhibition was a period of preincubation of bradykinin with the platelets. Inhibition of aggregation by bradykinin also was observed on canine platelets.Group for the Study of Mechanisms of Thrombosis, All-Union Cardiologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Sciences of the SSSR E. I. Chazov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 8, pp. 139–141, August, 1979.     

Haematological changes and up-regulation of P-selectin expression in circulating platelets of Indian women chronically exposed to emissions from biomass fuels

Blood cell counts and P-selectin expression of the circulating platelets of 37 Indian women that were chronically exposed to smoke from biomass fuel burning during cooking were evaluated. A total of 22 rural women that cook using LPG were simultaneously examined as controls. The biomass fuel users showed a significant reduction (p = < 0.05) in haemoglobin levels and erythrocyte counts and elevation (p = < 0.05) in total leukocytes, neutrophils and platelet counts. P-selectin expressing platelets were 8.6 ± 0.7% in biomass fuel users compared to 1.6 ± 0.2% in the controls. The absolute number of P-selectin expressing platelets was 8.3 times higher in biomass fuel users, and this increase also correlated with the number of years of exposure. The results demonstrated haematological alterations and remarkable activation of platelets in women chronically exposed to emissions from biomass fuel burning.     

Effect of liposomes on platelet function

The effect of different types of liposomes on the dynamic functions of platelets was studied. Liposomes of different composition (containing cholesterol and phosphatidylcholinethanolamine or not) and charge (containing negatively charged dicetyl phosphate or not) were shown to cause qualitatively similar but quantitatively slightly different effects and to modify the properties of the platelets: to reduce their powers of aggregation and their spherulation. The tendency for the platelets to aggregate was reduced by an increase in the concentration of liposomes, by an increase in the duration of incubation of the platelets with liposomes, and by the change from ordinary lecithin liposomes to liposomes containing phosphatidylcholinethanolamine. Suggestions are put forward regarding the mechanism of the observed phenomena and the absence of an unfavorable effect of various liposomes on platelet function is noted.All-Union Cardiologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 8, pp. 141–143, August, 1979.     

The platelet reversible endocytosis apparatus

The function of granules in rabbit platelets participating in the reversible endocytosis reaction was investigated. The reaction is induced by two types of inducers: proteolytic enzymes and compounds accumulating inside the granules (biogenic amines, dyes, anesthetics, phenothiazines). Heparin inhibits exocytosis induced by thrombin. In the case of exocytosis induced by accumulation of compounds within the granules of the platelets the cells lose their ability to maintain the aggregated state. The nature of the platelet granules participating in the reversible endocytosis reaction is discussed.Group for Thrombosis Mechanisms, All-Union Cardiologic Scientific Center, Academy of Medical Sciences of the USSR. (Presented by Academician of the Academy of Medical Sciences of the USSR E. I. Chazov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 7, pp. 5–8, July, 1979.     

Action of phospholipase a on aggregation of red cells and platelets

The effect of plasmin and trypsin on the activation of phospholipase and the action of phospholipase A (cobra venom) on the response of liberation and aggregation of red cells and platelets were studied. Trypsin and fibrinolysin activate phospholipase, and this is accompanied by the accumulation of nonesterified fatty acids in the blood serum. Phospholipase A induces liberation of thromboplastic factor from red cells and platelets and also their aggregation. Aggregation is inhibited by albumin and EDTA. It is postulated that the action of proteolytic enzymes on the blood cells is mediated through activation of phospholipase.Gor'kii Research Institute of Traumatology and Orthopedics. (Presented by Academician of the Academy of Medical Sciences of the USSR B. A. Korolev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 12, pp. 1411–1413, December, 1976.     

Platelet antigens in dogs

Four antigens specific for platelets and unconnected with antigens of red and white blood cells, were distinguished in dogs by the thromboagglutination test. Inheritance of platelet antigens in dogs is Mendelian in type and is controlled by several recessive genes.Laboratory of Experimental Surgery, A. V. Vishnevskii Institute of Surgery, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. S. Savel'ev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 12, pp. 1455–1457, December, 1976.     

Serotonin uptake by human platelets as a method of screening antidepressants

Antidepressants of the imipramine group considerably inhibit serotonin uptake by human platelets in concentrations of 10^–7 to 10^–5 M. Of the neuroleptics, only haloperidol (10^–5 M) significantly inhibits serotonin uptake by platelets. Amphetamine and cholinolytics do not affect serotonin uptake by platelets even in a concentration of 10^–4 M. The specificity of the effect of the antidepressants confirms the view that their thymoanaleptic action is an indirect effect brought about through activation of serotoninergic processes.Laboratory of Psychopharmacology, V. M. Bekhterev Leningrad Psychoneurological Research Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 1, pp. 51–53, January, 1976.     

Structural and functional organization of the hemostatic clot

Experimental data confirming the authors' hypothesis relating to structural and functional organization of the hemostatic clot are described. The basis of the clot is a fibrin-platelet structure in the meshes of which erythrocytes and leukocytes are distributed. Spontaneous compaction of the clot (retraction) takes place on account of the contractile properties of the surface structure of the activated platelets-extruded platelet cytogel. It is demonstrated that disturbance of the structure of the clot during aggregation of the platelets leads to inhibition of retraction. The sequence of processes taking place during formation and contraction of the clot is discussed.Laboratory of Thromboresistant Materials, Institute of Transplantation of Organs and Tissues, Ministry of Health of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. S. Savel'ev.) Translated from Byulleten' Éksperimental'nol Biologii i Meditsiny, Vol. 85, No. 2, pp. 132–136, February, 1978.     

Age differences in platelet protein biosynthesis and catabolism

The biosynthesis and catabolism of platelet proteins in adult and month-old rabbits were studied with the aid of lysine-¹⁴C in vivo. It was found that free lysine-¹⁴C does not pass through the membrane of platelets circulating in the blood stream and that it can appear in the platelet proteins only at the stage of thrombocytopoiesis. Protein formation in month-old rabbits takes place more slowly than in adult animals. The half-life of the total proteins of adult rabbit platelets averages 2 days, whereas in month-old rabbits it is lengthened to 3 days. The circulation of platelet proteins takes place more slowly in early postnatal development.Research Institute of Child and Adolescent Physiology, Academy of Pedagogic Sciences of the USSR, Moscow. [Presented by Academician of the Academy of Medical Sciences of the USSR A.A. Vishnevskii (deceased)]. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 1, pp. 20–21, January, 1977.     

Homocoagulation on contact of blood with polymer materials with electretic properties

The behavior of hemocoagulation was studied on polymer materials with electretic properties. Negative polarity of the electretic polymers was shown to lead to fibrinogenemia and to hypoadhesion of the platelets compared with electretic materials of positive polarity and with polymers with no static electricity. It is considered that adsorption of fibrin and hyperadhesion of platelets play the principal role in thrombogenesis on implanted polymers.Institute of Transplantation of Organs and Tissues, Ministry of Health of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 2, pp. 166–169, February, 1977.     

Mechanism of the hypercoagulant effect of hyperoxia

Inhalation of 100% O₂ at normal atmospheric pressure for 30 min is accompanied by an increase in the clotting power of the blood and a sharp decrease in the number of platelets, with changes in their structure, in man and rabbits. The trigger mechanism of this hypercoagulant effect is probably viscous metamorphosis of the platelets, developing under the influence of activation of Hageman's factor by oxygen.Kirghiz Medical Institute, Frunze. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 10, pp. 421–423, October, 1977     

Protective effect of L-carnitine on platelet apoptosis during storage of platelet concentrate

BackgroundPlatelet apoptosis is considered as one of the important factors involved in platelet storage lesion (PSL) and affect the quality of platelets during storage. The beneficial effect of L-carnitine (LC) on platelet apoptosis during platelet concentrates (PCs) storage has not been fully investigated. The aim of this study was to evaluate the effects of LC on platelets of PC regarding their apoptosis markers during storage.MethodsTen PCs from healthy donors were investigated in this study. PCs were prepared by platelet rich plasma (PRP) method and stored at 22 ± 2° C with gentle agitation during storage. The effects of LC (15 mM) on the platelet apoptosis were assessed by analyzing different indicative presence or absence of LC. Sampling was performed to evaluate apoptosis markers during platelet storage.ResultsThe results indicated significantly higher mitochondrial membrane potential for LC-treated platelets than the untreated on the days 2 and 5 of storage (P_day2 = 0.001, P_day5 = 0.001). Phosphatidylserine (PS) exposure significantly increased on the untreated compared with LC-treated platelets on the second and third days of storage (P_day2 = 0.014, P_day3 = 0.012). Also, active caspase 3 was lower in the LC- treated platelets than the control group on the day 5 of storage (P_day5 = 0.004). Cytosolic cytochrome C was so significantly lower in LC-treated compared to the untreated platelets during storage time (P_day2 = 0.002, P_day3 = 0.001, Pday5 = 0.001).ConclusionThe results of this study indicate that the use of LC as an additive solution in platelets may be useful to reduce PSL by decreasing platelet apoptosis via mitochondrial pathway and increase platelet quality during storage.     

Anti-β2 Glycoprotein I Antibodies Prevent the De-activation of Platelets and Sustain their Phagocytic Clearance

Exposure to phosphatidylserine (PS) tags dying and senescent cells for removal and identifies activated platelets. In this study we followed the fate of PS-exposing platelets in the presence of antibodies purified from Systemic Lupus Erythematosus (SLE) and primary Anti-phospholipid Syndrome (APS) patients' sera by β2GPI affinity chromatography. Thrombin-activated platelets exposed PS and associated to β2GPI. Both events were required for recognition by antibodies. Human monocyte-derived macrophages phagocytosed activated platelets only. Each macrophage internalized an average of 3.16±0.2 platelets after 60 min at 37°C. Phagocytosis did not increase after longer incubations (4.65±0.26 platelets internalized by each macrophage after 300 min). Recognition of platelets by anti-β2GPI antibodies significantly increased phagocytosis (P< 0.01). Upon withdrawal of thrombin, platelets downregulated PS (PS exposure t_1/2: 242 min) and the ability to be recognized by macrophages. Purified β2GPI bound to PS-exposing platelets (association t_1/2: 250 min). Phosphatidyl serine exposure and β2GPI association had virtually identical kinetics. Antibody binding prolonged the exposure of the β2GPI/PS complex (t_1/2: >1200 min). The ability to phagocytose opsonized platelets was accordingly sustained (5.3±0.2 opsonized platelets were internalized by each macrophage after 60 min and 9.4±0.3 after 300 min). Anti-β2GPI antibodies therefore poise activated platelets in a PS-exposing status, preventing the recycling of their function and favoring their phagocytic clearance.     

Refractoriness of red blood cells and platelets

The effect of proteolytic enzymes and of arachidonic acid on aggregation of red blood cells and platelets was studied. These substances were found to stimulate aggregation of the blood cells. Preliminary incubation of fibrinolysin, trypsin, and arachidonic acid with suspensions of blood cells, however, is followed by a marked decrease in their ability to aggregate, i.e., by the development of a refractory state. The possible mechanism of this phenomenon is discussed.Research Institute of Traumatology and Orthopedics, Gor'kii. (Presented by Academician of the Academy of Medical Sciences of the USSR B. A. Korolev.) Translated from Byulletin' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 11, pp. 524–526, November, 1977.