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.     

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.     

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.     

Interaction between bradykinin,morphine, and naloxone at the sensomotor cortical unit level

The effects of bradykinin, morphine, and naloxone applied by microiontophoresis on sensomotor cortical neurons were studied in waking rabbits. Bradykinin increased the discharge frequency of most neurons. Morphine inhibited unit activity. Against the background of morphine, bradykinin had no activating action. Naloxone abolished the depriming effect of morphine and restored the response of the neurons to bradykinin. It is concluded that bradykinin interacts with opiate receptors in the brain.Laboratory of Molecular Neurophysiology and Biochemistry, P. K. Anokhin Institute of Normal Physiology, Academy of Medical Sciences of the USSR, Moscow. Laboratory of Pharmacology of the Nervous System, Institute of Pharmacology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 12, pp. 683–685, December, 1979.     

Bradykinin as a factor regulating synaptic input toHelix pomatia neurons

The effect of bradykinin on spontaneous unit activity was studied in the subesophageal ganglion ofHelix pomatia by microiontophoresis. Bradykinin was shown not only to facilitate unit responses to synaptic activation, but also to prolonged action potential generation evoked by this activation. The effects of bradykinin were observed in experiments carried out during the spring.Laboratory of Emotions and Emotional Stress, P. K. Anokhin Institute of Normal Physiology, and Laboratory of Pharmacology of the Nervous System, Institute of Pharmacology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 7, pp. 48–50, July, 1979.     

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.     

Action of KCN on intact and refractory platelets

The action of potassium cyanide on ADP-induced aggregation of intact and refractory platelets was investigated. Cyanide (5·10^–4 M) had virtually no effect on the aggregation of intact cells but stimulated aggregation of refractory platelets. The stimulating effect of the inhibitor on aggregation was not connected with liberation of further quantities of ADP from the cells. Differences in the sensitivity of the aggregating power of intact and refractory cells to partial depression of metabolism is discussed in terms of the calcium model of autoregulation of platelet aggregation suggested previously.Research Institute of Child and Adolescent Physiology, Academy of Pedagogic Sciences of the USSR, Moscow. (Presented by Academician V. N. Chernigovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 8, pp. 940–943, August, 1976.     

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.     

Effect of bradykinin and morphine on sensomotor cortical neurons in rats

Acute experiments on rats showed that bradykinin, injected by microiontophoresis, activates sensomotor cortical neurons in rats. Morphine, administered in the same way, prevents the development of the bradykinin effect. Bradykinin, it is suggested, acts on opiate receptors in cerebral cortical neurons.Laboratory of Pharmacology of the Nervous System, Institute of Pharmacology, Academy of Medical Sciences of the USSR. Laboratory of Emotions and Emotional Stresses, P. K. Anokhin Institute of Normal Physiology, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov). Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 10, pp. 450–452, October, 1978.     

Changes in resistance of partially hepatectomized mice to transplantable tumors in the final stage of regeneration of the liver

When an ascites form of hepatoma 22a was transplanted intraperitoneally into A/he mice 1–12 days after partial hepatectomy two periods of inhibition of its growth were observed. The first 24 h after the operation and the second 3–10 days later. Animals most resistant to transplantation of this particular tumor (5–8 days after transplantation of sarcoma 37 and Ehrlich's adenocarcinoma.Laboratory of Growth and Development, 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. 83, No. 3, pp. 326–328, March, 1977.     

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.     

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.     

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.     

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.     

A model of disseminated intravascular blood clotting

Vascular-platelet and plasma hemostasis was studied in dogs after blood loss (40–45 ml/kg body weight) followed by hypervolemic (60–65 ml/kg body weight) transfusion of homologous (from three donors) plasma enriched with platelets and leukocytes. After a brief phase of hypercoagulation, hypocoagulation was discovered in all the experimental dogs, accompanied by a reduction in the platelet count and in the intensity of platelet aggregation, lengthening of the bleeding time, a decrease in the resistance of the capillary wall, a decrease in the plasma fibrinogen concentration and activity of factor XIII, and an increase in the fibrinolytic activity of the blood. The results are evidence of the development of an acute syndrome of disseminated intravascular blood clotting.Laboratory of Pathophysiology, Central Research Institute of Hematology and Blood Transfusion, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Fedorov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 7, pp. 116–120, July, 1978.     

Importance of the time of bone marrow transplantation for manifestation of allogeneic inhibition of stem cells

The effect of duration of the interval (4–96 h) between irradiation of F₁ (CBA×C57BL/6) hybrids and transplatation of bone marrow from C57BL/6 mice on manifestation of allogeneic inhibition of the stem cells was studied. In this particular donor-recipient model the degree of allogeneic inhibition was 90%. Transplantation of bone marrow carried out 4–48 h after irradiation had no effect on the number of colonies in the spleen of the F₁ hybrids. Considerable abolition of allogeneic inhibition (33%) was observed if the parental cells were injected 96 h after irradiation. Remote transplantation had no effect on the number of colonies in the spleen of syngeneic recipients.Laboratory of Experimental Genetics, Institute of Medical Genetics, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Zhukov-Verezhnikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 3, pp. 347–348, March, 1976.     

Relationship between effectiveness of the antitumor action of sarcolysin and the latent period of tumor development after transplantation

After transplantation of a sarcoma induced by 3-methylcholanthrene into syngeneic mice the latent period of development of the tumor varied from 7 to 26 days. Sarcolysin was injected as a single dose at the moment of detection of the tumor by palpation. When the latent period of development of the tumor was 7–8 and 10–15 days, inhibition of its growth was accompanied by an increase in the survival period of the mice, and the increase was particularly great in the latter group. If the latent period of tumor development was 17–20 or 22–26 days, inhibition of tumor growth was not accompanied by an increase in the survival period of the mice.Laboratory of Mechanisms of Action of Antitumor Preparations, Oncologic Scienctific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Kraevskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 2, pp. 197–199, February, 1978.     

Action of bradykinin on the mesenteric microcirculation in rats

Responses of the mesenteric microvessels of rats to application and intravenous injection of bradykinin were studied in acute experiments using intravital microscopy. No clear bioelectric response of the smooth-muscle cells of the microvessels to local application of bradykinin could be found in electrophysiological experiments. In another series of experiments the dynamics of vasomotor activity were studied after the same treatment by the split-image method. The response of the microvessels to bradykinin application was shown to vary in character depending principally on whether the preparation was being applied for the first or subsequent time. It is suggested that bradykinin acts on the mesenteric microvessels through the intermediary of other vasoactive substances.Laboratory of General Pathology and Experimental Therapy, Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 3, pp. 259–261, March, 1976.     

Character of the immune response in rats and mice with adjuvant disease

Phasic changes in the immune response were observed in rats and mice with adjuvant disease: stimulation of antibody formation on the seventh day after injection of Freund's complete adjuvant (FCA) and inhibition on the 21st day. Inhibition of production of normal antibodies against 0- and Vi-typhoid antigens also was demonstrated.Laboratory for the Study of Nonspecific Resistance of the Organism and Immunity, Institute of General Pathology and Pathophysiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éxperimental'noi Biologii i Meditsiny, Vol. 86, No. 10, pp. 462–465, October, 1978.     

Role of endoperoxides of the prostaglandins in platelet aggegation

Phospholipase A and lysolecithin stimulate the reaction of liberation of thromboplastic factor and aggregation of erythrocytes and platelets. Polarographic investigations have shown that these aggregating agents cause absorption of O₂ in medium containing platelets, possible evidence of the formation of these conditions of intermediate products of prostaglandin synthesis, namely endoperoxides. Albumin does not prevent the liberation reaction and the absorption of O₂ caused by phospholipase and lysolecithin but it completely inhibits their aggregating action. Aspirin, on the other hand, blocks O₂ consumption by platelets althoug its action on the aggregating effect of lysolecithin is only very slight. It is suggested that the aggregation of the blood cells is connected with perturbation of the lipid-protein structure of their membranes and not with endoperoxide synthesis.Gor'kii Research Institute of Traumatology and Orthopedics. (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. 84, No. 7, pp. 13–16, July, 1977.