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At least 451 records · Page 25Linked to original sources
PubMed1993

Effect of the electret-blood contact time on the adhesion of human blood platelets.

The paper presents the results of research into the time characteristics of adhesion of platelets to the electret surface made from polyethylene terephthalate PET foil of 36 microns thickness. The electrets were formed by using the electron beam method. The method based on the electrostatic induction phenomenon was utilized to measure the electric charge surface density. Evaluation of the time characteristics of the adhesion of blood platelets was performed on the basis of microscopic examination and with the use of the chamber method for determining the number of blood platelets in the phase microscopy. The results obtained have confirmed the influence of the electret effect on PET foil thrombogenesis. The number of spacious aggregates found on the surfaces being analysed did not undergo any changes despite the extension of the electret--blood contact time. The stationary course of the adhesion process as well as the unappreciable amount of blood platelets on the surface have proved that the negative electric charge makes it possible to obtain thrombogenic materials.

Biocompatible Materials↗
PubMed1989

[Superoxide dismutase activity and malonic dialdehyde level in blood platelets of patients with coronary disease].

The investigations aimed at evaluating free superoxide radicals generation and the degree of blood platelets cell membrane lipids peroxidation on the base of superoxide dismutase activity and malonic dialdehyde level in patients with ischaemic heart disease. The obtained results have shown that blood platelets superoxide dismutase activity is markedly lower in patients with ischaemic heart disease than in healthy individuals whereas malonic dialdehyde levels are markedly higher.

Adult↗
PubMed1984

Blood platelet function, medicinal agents, and other chemical entities.

An overview is presented on blood platelet function, including the interaction of platelets with the vessel wall and with medicinal agents and related chemical entities. Current interpretations are discussed in terms of the most recent biological, chemical, and physicochemical concepts.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1988

In-vitro platelet sensitivity to collagen-induced aggregation and in-vitro platelet deterioration rate during storage, are both inversely proportional to the in-vivo blood platelet concentration in normal individuals: preliminary documentation of these theoretically predictable relationships.

This preliminary study documents two new functional relationships for platelets obtained from normal subjects, whose individual blood platelet concentrations (IBPCs) are in the normal range. Firstly, platelets from subjects (or donors) with high-normal IBPCs are the least sensitive to collagen-induced aggregation (a significant inverse correlation). This may be of importance in determining the likely efficacy of fresh platelet transfusions obtained from donors with different IBPCs within the normal range. Secondly, platelets from subjects/donors with high-normal IBPCs deteriorate less rapidly during storage (a significant inverse correlation), perhaps due to differences in platelet biochemical activity between individuals. Such measurements of platelet deterioration rate were based upon the development of a new experimental technique, in which sterile test-PRP was incubated at 37 degrees C with continuous (quarter-hourly) indirect measurements of changes in platelet morphology. This tube-based method is described in detail. The functional relationships observed do have a theoretical basis within the work of others, which is appopriately outlined. Particular discussion pivots around the possibility of using the deterioration rate relationship to predict how therapeutic platelet concentrates prepared from a given donor of know IBPC, may retain their morphological integrity during routine blood bank storage.

Adolescent↗
PubMed1976

Uptake of 5-hydroxytryptamine by rat blood platelets and its inhibition by adenosine 5'-diphosphate.

1 The uptake of 5-hydroxytryptamine (5-HT) by rat blood platelets in citrated plasma was linear for at most 10 s and was substantially complete within 3 minutes. 2 Adenosine 5'-diphosphate (ADP) was a potent inhibitor of 5-HT uptake (Ki=0.38 muM) and kinetic analysis revealed that the inhibition was not competitive. 3 Inhibition of 5-HT uptake by ADP was abolished in the presence of prostaglandin E1 and 2-n-amylthio-AMP, which also inhibit the stimulant actions of ADP on blood platelets. 4 It is concluded that ADP could inhibit 5-HT uptake by changing the Na+/K+ distribution across the cell membrane, and the biological significance of this is discussed.

Adenosine Diphosphate↗
PubMed1983

Studies on the stimulation of human blood platelets by semi-synthetic platelet-activating factor.

"Saturated" and "unsaturated" platelet-activating factor (PAF) obtained from ratfish liver oil were proved to exert potent stimulation on human blood platelets. Using 0.025 to 1.0 mumol/1 PAF a dose-dependent platelet aggregation in platelet-rich plasma was observed. During PAF-induced irreversible aggregation a 9 to 40% release of platelet bound serotonin occurred. The specific effect of PAF, however, seems to be limited to induce reversible aggregation since second wave of aggregation and serotonin release were suppressed by a combination of acetylsalicylic acid and an ADP scavenging system. Incubation of PAF for 30 min in plasma resulted in a 90% loss of its platelet aggregating power. Subthreshold concentrations of PAF enhanced the platelet aggregation triggered by suboptimal concentrations of ADP, epinephrine, or collagen. Vice versa non-aggregating concentrations of ADP, epinephrine, collagen, Ca-ionophore A 23,187, or arachidonic acid amplified PAF-induced platelet aggregation. The synergistic effect of PAF and other stimuli of blood platelet activation can be partly interpreted as a stimulating effect of PAF on the metabolization of arachidonic acid.

Adenosine Diphosphate↗
PubMed1982

The content of coenzyme A, acetyl-CoA and long-chain acyl-CoA in human blood platelets.

The amounts of coenzyme A (CoASH) and acetyl-CoA in the acid-soluble extract of human blood platelets were quantitated by an isocratic reversed-phase liquid-chromatographic system. The analytical column was Supelcosil LC-18, and the solvent was 220 mmol/l potassium phosphate, pH 4.0, and 120 ml/l methanol. Long-chain acyl-CoA was estimated by the released coenzyme A after an alkaline hydrolysis of the acid-insoluble material of the blood platelets. The median values in platelets from fourteen healthy persons were 30 pmol CoASH/mg platelet protein, 45 pmol acetyl-CoA/mg platelet protein, and 34 pmol long-chain acyl-CoA/mg platelet protein.

Acetyl Coenzyme A↗
PubMed2006

The adhesion of blood platelets on fibrinogen surface: comparison of two biochemical microplate assays.

The biocompatibility of materials is frequently assessed by blood platelet adhesion, since platelet adhesion plays a considerable role in blood interaction with artificial surfaces. Blood platelets adhesion is an essential event in haemostatic and thrombotic processes. The aim of this study was to simultaneously compare simple biochemical assays widely used for evaluation of platelet static adhesion based on the determination of enzymatic activity of either lactate dehydrogenase (LDH) or acid phosphatase (ACP) in lysates of adhered platelets. Adhesion of platelets from platelet-rich plasma and washed platelets activated by either ADP or thrombin on surfaces covered with fibrinogen and well defined fibrin was studied. The results demonstrated that the amounts of adhered platelets estimated by the LDH method were significantly lower as compared with the amount obtained by ACP method. LDH but not ACP release from platelets during adhesion was shown to take place. It suggests that the LDH method should be used rather as an assay of platelet integrity. The ACP method is much more suitable for quantitative determination of platelet adhesion especially in the development and evaluation of haemocompatibility of new biomaterials.

Acid Phosphatase↗
PubMed1980

Intracellular localization of palmitoyl-CoA hydrolase and palmitoyl-CoA synthetase in human blood platelets and liver.

The intracellular localization studies of human blood platelets by sucrose gradient and differential centrifugation, showed that palmitoyl-CoA hydrolase was mainly localized in the cytosol fraction. However, a localization also in the mitochondrial fraction seems possible as disruption of platelets by the French press and nitrogen decompression techniques resulted in mitochondrial damage. In human liver the palmitoyl-CoA hydrolase was localized in the mitochondrial and microsomal fractions. Palmitoyl-CoA synthetase was localized in the mitochondrial and microsomal fractions in both platelets and liver. The possible physiological implications of these differences, and the finding of a very high ratio of palmitoyl-CoA hydrolase/palmitoyl-CoA synthetase in platelets compared with liver, are discussed.

Blood Platelets↗
PubMed1983

Effects of amoxapine on serotonin uptake in human blood platelets of depressed patients and normal controls.

The effect of amoxapine and imipramine on the serotonin (5-HT) uptake of blood platelets from depressed patients and normal controls was studied ex vivo or in vitro, respectively. Amoxapine was approximately one-tenth as potent as imipramine in inhibiting 5-HT uptake in blood platelets from normal controls in vitro. Both drugs inhibited 5-HT uptake in a competitive manner. However, ex vivo studies demonstrated that imipramine produced a mixed inhibition and amoxapine, a competitive inhibition of 5-HT uptake. There was no relationship between the change in the platelet affinity for 5-HT after treatment with amoxapine and clinical response to amoxapine.

Adult↗
PubMed1989

Purification and characterization of a calcium binding protein with "synexin-like" activity from human blood platelets.

A calcium binding protein of Mr = 54,000 has been isolated from human blood platelets. This protein has been shown to enhance Ca2+-induced aggregation of phosphatidylserine liposomes, suggesting that it may be a member of a recently recognized class of binding proteins known to interact with phospholipids and the membrane in a Ca2+ dependent manner. Because of the "synexin-like" activity of this protein it may be involved in Ca2+ regulated platelet secretion as well as cell motility.

Annexin A7↗
PubMed1991

Leaching of plasticizers from and surface characterization of PVC blood platelet bags.

The leaching of phthalate plasticizers from four types of blood platelet bags was investigated. The anticoagulant solutions used in the blood collection bags had pH values of 5.64 +/- .04 and contained no detectable amounts of phthalates. Platelet bag materials from each bag were soaked in normal salines for up to 5 days. The salines were tested for the leached phthalates from the bags but none could be found. However, di-(2-ethylhexyl) phthalate (DEHP) leached out of the PL-146 and Terumo bags into bovine calf serum used for soaking the bag materials. There was an increase in the amount of DEHP leached from about 1.1 mg at the end of one day to about 3.3 mg per gm of bag material at the end of a five day extraction with the serum. In PL-732 sets, a platelet bag made of a specialty polyolefin, the amount of DEHP leached out was less than 0.02 mg per g of bag material. CLX bags, which contained tri-(2-ethylhexyl) trimelliate (TETM) as a plasticizer, showed a negligible amount of it leaching into the calf serum. Infra-red spectra showed that PL-146 bags had been coated with a layer of a fatty acid amide while the Terumo bags contained a layer of a silicone fluid on their inner surfaces. CLX bags showed a coating of stearates, which were probably soaps of calcium or zinc. Scanning electron microscopy (SEM) showed that the inner surfaces of each brand of the bag were distinctly different morphologically. The two PVC bags were very similar whereas the surfaces morphology of PL-732 was rougher. Terumo bag had a different surface morphology than those of the other bags whereas the CLX bags had a very regular surface pattern. The exact significance of the surface morphology is not certain but excessively rough surfaces may not be desirable for the bags.

Benzoates↗
PubMed1981

Interaction of D-LSD with blood platelets of rabbits: shape change and specific binding.

In blood platelets of rabbits, the shape change-inducing effect of D-lysergic acid diethylamide (D-LSD) has been compared with the D-LSD-binding. D-LSD, but not L-LSD, caused a shape change reaction (EC50 1.3 x 10(-9) M) which was inhibited by various 5-HT antagonists (methergoline and neuroleptic drugs), butaclamol showing marked stereospecificity. Strong inhibitors of 5 HT uptake were only weak in counteracting the D-LSD-induced shape change. Furthermore, D-[3H]LSD bound to platelets at a single saturable, high affinity, stereoselective site [Kd = (31.1 +/- 3.3) x 10(-9) M; Bmax = 28.9 +/- 2.7 fmols per 10(8) platelets]. This binding was strongly antagonized by D-LSD and methergoline and less by the hallucinogenic drugs, psilocin, bufotenin and N'N'-dimethyltryptamine. L-LSD an 5 HT, inhibitors of 5 HT uptake and neuroleptics, especially spiroperidol and butaclamol, had only a weak antagonistic effect. The latter showed stereospecificity. It is concluded that 1) the shape change reaction caused by D-LSD in platelets is mediated by the specific 5 HT-receptor, 2) the sites mediating the D-LSD-induced shape change reaction are not identical with those responsible for D-[3H]LSD-binding and both these sites are different from the 5 HT-transport sites and 3) with respect to D-LSD-binding sites, platelets and neurons are not exactly identical.

Animals↗
PubMed2000

[Phagocytic activity of blood platelets before and after renal artery embolization in patients with renal cancer].

Embolization consists in the occlusion of renal artery and its ramifications, which induces acute renal infarction. Renal artery embolization, causing necrosis, stimulates cellular reactions within and around the neoplasm. The interaction of neoplastic cells with blood platelets is of great importance in the development of neoplastic disease. Neoplastic cells exert a stimulatory effect on blood platelets. During activation, platelets change in shape and secrete certain substances. We conducted this study measuring the phagocytic activity of blood platelets. 45 patients suffering from renal cancer were examined (22 women and 23 men) before and after embolization. Diagnosis was established basing on the patients' history, clinical picture, and ultrasonographic, urographic and angiographic examinations. The study demonstrated that embolization led to an increase in platelet count and decrease of phagocytic index.

Adult↗
PubMed1984

Investigation of human blood platelets with fluorescence spectroscopy.

Intramolecular excimer formation of dipyrenylpropane was investigated in human blood platelets. The ratio of the emission intensities of excimer to monomer (IE/IM) is sensitive to changes in lipidic membrane structure, induced by external perturbations, such as cholesteryl hemisuccinate introduction and temperature. Lack of reliable "microviscosities" determinations could be due to poor solubility of the probe in aqueous cells suspensions. Results were compared to those obtained with the fluorescence polarization technique.

Blood Platelets↗
PubMed2005

Resveratrol, a phenolic antioxidant with effects on blood platelet functions.

The main purpose of this article is to provide an overview of the currently available evidence of antiplatelet properties of resveratrol (3,4('),5-trihydroxystilbene). Resveratrol, a phenolic compound found naturally in fruits, nuts, flowers, seeds and bark of different plants is integral part of human diet. It exhibits a wide range of biological effects, including antiplatelet, anti-inflammatory, anticancer, antimutagenic and antifungal properties. It is also a potent antioxidant, reactive oxygen species scavenger and metal chelators. Resveratrol reduces lipid peroxidation, oxidation and nitration of platelet and plasma proteins. This review article describes the chemical structure of resveratrol, its biological activity, the effects on blood platelet functions and the mechanisms involved in its action on blood platelets, the cells which play an important role not only in the haemostatic process, but also in pathogenesis of cardiovascular diseases.

Animals↗