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Biomedical subjects

A Dvilansky

Publications and source records attributed to A Dvilansky.

At least 55 records · Page 3Linked to original sources
PubMed1984

Effects of ethanol, CBD and delta 'THC on proliferation of K-562 cells.

The effect of ethanol and cannabinoids on proliferation of the leukaemic cell line K-562 is described. The effects on the cells were assessed by counts of viable cells and 3H thymidine incorporation. delta 'THC was found to attenuate the proliferation of K-562 cells, the effect being prominent at 10(-4)M. CBD was effective only at high concentrations or after prolonged incubation time. Both drugs were dissolved in 0.3% ethanol solution; ethanol itself caused a biphasic effect, namely a mild increase in K562 proliferation at low concentrations and a marked attenuation at higher concentrations.

Cannabinoids↗
PubMed1984

Effect of activators and inhibitors on human blood platelets: study by freeze-fracturing technique and electron microscopy.

Samples of normal human platelet-rich plasma were activated by ADP (0.5 microM and 20 microM) or by cold treatment (4 degrees C). The effects of incubation in EDTA, colchicine or cytochalazin B were also studied. Samples were prepared by the freeze-fracturing technique and examined by electron microscopy. Faces of fractured membranes were examined for aggregation of particles, for pore-openings in the membrane, and for the general morphological appearance of the membrane-fractured faces. No aggregation of particles was found in platelet-rich plasma preparations treated with ADP, EDTA, colchicine or cytochalazin B, nor did the pore openings reveal any changes following these treatments. We conclude that platelet activation and an increase in microviscosity of the platelet membrane is not due to platelet aggregates in the membrane.

Adenosine Diphosphate↗
PubMed1983

Plasma thromboglobulin and platelet aggregation index in transient ischaemic attack: effect of aspirin and dipyridamole therapy.

Beta-thromboglobulin (beta TG) plasma levels and platelet aggregation index (PAI) were determined in 14 transient ischaemic attack (TIA) patients, before and two weeks after starting therapy with aspirin and dipyridamole. Thirty healthy men were the control group. Decrement in beta TG plasma levels (without statistical significance) was found in treated patients when compared to the period before treatment. It is noteworthy that both these levels were significantly higher than plasma beta TG levels of normal controls. A highly significant difference was found between PAI of patients before treatment compared with PAI of patients treated with aspirin and dipyridamole. PAI was higher and similar to PAI of controls in the treated patients. No correlation between these two tests was established. It is concluded that the beta TG test is efficient as an aid for diagnosis of TIA, while PAI is better tool for follow-up.

Adult↗
PubMed1982

Impairment of platelet aggregation by Echis colorata venom mediated by L-amino acid oxidase or H2O2.

Echis colorata bites cause impairment of platelet aggregation and hemostatic disorders. The mechanism by which the snake venom inhibits platelet aggregation was studied. Upon fractionation, aggregation impairment activity and L-amino acid oxidase activity were similarly separated from the crude venom, unlike other venom enzymes. Preparations of L-amino acid oxidase from E. colorata and from Crotalus adamanteus replaced effectively the crude E. colorata venom in impairment of platelet aggregation. Furthermore, different treatments known to inhibit L-amino acid oxidase reduced in parallel the oxidase activity and the impairment potency of both the venom and the enzyme preparation. H2O2 mimicked characteristically the impairment effects of L-amino acid oxidase and the venom. Catalase completely abolished the impairment effects of the enzyme and the venom. It is concluded that hydrogen peroxide formed by the venom L-amino acid oxidase plays a role in affecting platelet aggregation and thus could contribute to the extended bleeding typical to persons bitten by E. colorata.

Amino Acid Oxidoreductases↗
PubMed1982

Studies of the effect of auranofin, a new antiarthritic agent, on platelet aggregation.

Auranofin (AF), at a concentration of 10 micrograms/ml, was found to be a potent inhibitor of ADP-, epinephrine-, or collagen-induced platelet aggregation utilizing platelet-rich plasma obtained from human blood. In contrast, aurothioglucose was less effective than AF in inhibiting epinephrine- or collagen- induced platelet aggregation. The inhibitory effect of AF was more evident on the second phase of aggregation. The inhibitory effect of AF was more evident on the second phase of aggregation and was a function of drug preincubation time. Compared to platelet-rich plasma, washed platelets were superior for detecting the inhibitory action of AF (greater than or equal to 0.1 microgram/ml) on ADP-induced platelet aggregation. This potent inhibitory action of AF on ADP-induced platelet aggregation was antagonized by dithioerythriol, a potent reducing agent. These results suggest that AF can inhibit both platelet release and aggregation mechanisms which may be relevant to its antiarthritic activity. Further studies are required to elucidate the cellular mechanism by which AF inhibits platelet aggregation.

Adenosine Diphosphate↗
PubMed1982

Management of pregnancies with rare blood types.

Pregnant women with antibodies to high incidence blood group antigens should be diagnosed as early as possible and red blood cells should be stored frozen for future possible needs. Either autologous, compatible siblings or unrelated individuals' red blood cells should be frozen. The application of such a program is described in three pregnant women with exceedingly rare antibodies to high incidence blood group antigens (anti-Lutheranb, and PP1Pk, and anti c with blood type B CCddee Du negative).

Adult↗
PubMed1982

Effect of cannabinoids on the activity of monoamine oxidase in normal human platelets.

Platelet MAO activity was affected by preincubation with cannabinoid derivatives in vitro. The psycho-active derivative delta 1-THC inhibited MAO activity in platelets to an extent varying according to its concentration while CBD and (+) delta 6-THC had no inhibitory effect. (-) delta 6-THC, which is minor psychomimetic component, had less inhibitory effect on MAO activity than delta 1-THC. However, (-) DMH delta 6-THC revealed no attenuation effect on MAO inspite of its well-known psychomimetic activity.

Adolescent↗
PubMed1981

Liquid stored erythrocytes: agglomeration, morphology, sialic acid, and toluidine blue uptake studies.

Increased tendency to reversible agglomeration in erythrocytes in outdated units has been previously demonstrated. This phenomenon occurred while post transfusion viability was still acceptable. In the present study erythrocytes of units with early agglomeration were investigated and compared with those with late agglomeration. There was no morphological characterization of these erythrocytes and their sialic acid content and the toluidine blue uptake were not lower than in late agglomeration. Thus, it seems that agglomeration reflects membranal changes, but is not directly related to the sialic acid content of the membrane or to its toluidine blue uptake.

Blood Preservation↗
PubMed1981

Performance of a new type of blood oxygenator.

A new type of direct-contact oxygenator has been tested satisfactorily on dogs in nine experiments. It is based on the principle of the "packed column" and has the advantage of a small hold-up (meaning a small priming volume), no formation of foam, and gentle flowing of the blood. The apparatus is simple enough to be commercially available at a low price and discarded after use. Both PO2 increase and PCO2 decrease were satisfactory and plasma hemoglobin values remained low after 75 minutes of perfusion. Preliminary in vitro experiments on ox and human blood showed a low degree of blood damage.

Animals↗
PubMed1981

Detection of anti-platelet antibodies in patients with idiopathic thrombocytopenic purpura (ITP) and in patients with rubella and herpes group viral infections.

A highly sensitive enzyme-linked immunosorbent assay (ELISA) technique was observed for serological detection of antibodies against platelets. A covalently bound to Sepharose CL-4B was used to enrich sera in the IgG3 subclass of antibodies. The ELISA procedure as applied to detect anti-platelet antibodies in patients with herpes or rubella viral infections and in patients with idiopathic thrombocytopenic purpura (ITP). Twenty-eight sera from 13 thrombocytopenic patients showed high levels of anti-platelet antibodies. Two splenectomized patients in remission became negative for anti-platelet antibodies. Seventy-four sera from patients with serological diagnosis of herpes group viral infections comprising 10 cases of cytomegalovirus, nine cases of varicella or zoster, six cases of herpes simplex and four cases of Epstein-Barr virus were examined for the presence of anti-platelet antibodies. Except for two patients with varicella and zoster and one patient with rubella infection, all cases examined showed positive titres of anti-platelet antibodies. Sera from a group of 51 healthy controls were evaluated for anti-platelet antibodies. Forty-nine (96%) were negative (less than 40), whereas the other two were only slightly positive.

Adolescent↗
PubMed1980

Membrane dynamic alterations associated with activation of human platelets by thrombin.

Two fluorescent probes, N-carboxymethylisatoic anhydride, which binds to membrane proteins, and 1,6-diphenyl-1,3,5-hexatriene, a lipophilic label, have been used to follow membrane microenvironmental changes. Activation of human platelets by thrombin resulted in a simultaneous increase in values of fluorescence polarization (P) of both probes during the stages of shape change and secretion, which further increased during platelet aggregation. The similar pattern of changes in P for both probes indicates the interdependence of lipids and proteins in the activated platelet membrane.

Blood Platelets↗
PubMed1979

Membrane microenvironmental changes during activation of human blood platelets by thrombin. A study with a fluorescent probe.

Membrane microenvironmental changes associated with thrombin-induced platelet activation were followed by fluorescence intensity and polarization studies of 1,6-diphenyl-1,3,5-hexatriene (DPH)-labeled human platelets. The labeling of washed platelets with DPH did not alter platelet intactness and morphology. In response to thrombin, DPH-labeled platelets exhibited reduced serotonin release, yet aggregation was barely inhibited. Shape change induced by thrombin or ADP was indistinguishable in control and in DPH-labeled platelets. During platelet aggregation induced by thrombin, fluorescence intensity increased by about 14%, which may indicate a more hydrophobic exposure of the probe. However, no change in fluorescence was detected during platelet shape change, induced either by thrombin in presence of EDTA or by ADP. Thrombin-activated platelets exhibited an increase in values of fluorescence polarization (P) during the stages of shape change and secretion, which further increased during aggregation. A similar pattern of increase in P values characterized platelet shape changes, caused either by thrombin in the presence of EDTA or by ADP. Changes in individual platelets are discernible from the alterations of the aggregating cells. These results may indicate that platelet activation is accompanied by an increase in rigidity of the membrane lipids. Functionally, the elevated "microviscosity" may reflect a primary role of membrane lipids in modulating the process of platelet activation or secondary transitions in lipids due to membrane events mediated by proteins.

Adenosine Diphosphate↗