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PubMed1994

Influence of Pall Pl-50 platelet filters on lactate dehydrogenase, platelet factor 4, and complement factor 3 in stored platelet concentrates.

BACKGROUND: The study examines Pall Pl-50 platelet filters with respect to their influence on some biochemical properties of platelet concentrates. MATERIAL AND METHODS: Ten pairs of pooled platelet preparations, each consisting of 3 platelet concentrates, were studied. On day 1, one of the preparations was filtered and the other served as an identical non-filtered control. Immediately after filtration platelet counts, the levels of desarginated activated complement factor 3 (C3a), extracellular levels of lactate dehydrogenase (LDH) and extracellular and total concentrations of platelet factor 4 (PF4) were determined in both concentrates. After 5 days sterility testing and determination of extracellular levels of PF4 and LDH were performed. RESULTS: Extracellular concentrations of PF4 and C3a decreased immediately after filtration (p < 0.01). Furthermore, Pall Pl-50 filters caused cellular instability reflected by an increased release of PF4 (p < 0.01) during subsequent storage. CONCLUSION: Platelet concentrates filtered with Pall Pl-50 would not appear suitable for storage.

Blood Preservation↗

PubMedDate not supplied

Correlation of platelet concentration in platelet-rich plasma to the extraction method, age, sex, and platelet count of the donor.

An important reason to improve methods of isolating platelet-rich plasma (PRP) is the potential use of autologous platelet growth factors. In addition to discontinuous plasma separation, a second method for extraction of PRP has now become available, which can be performed directly by the surgeon. In this study, the suitability of the 2 methods of producing PRP was compared. Whole blood was drawn from 158 healthy donors (112 men, 46 women) aged 20 to 62 years (mean 34, SD 10). The PRP was separated by the discontinuous plasma separation method (by the blood bank) or by the so-called "buffy coat" method (the "self-concentration" method, analogous to the PRP Kit, Curasan, Kleinostheim, Germany). Platelet counts differed significantly according to donor blood (median men 237,500/microL, women 272,000/microL), blood bank PRP preparation (median men 1,302,000/microL, women 1,548,500/microL), and self-concentrated PRP (median men 944,000/microL, women 1,026,000/microL). The platelet concentration of the blood bank PRP correlated with the platelet count in the donor whole blood (Spearman's correlation coefficient r(s) = 0.73). However, there was no significant correlation between the platelet count of self-concentrated PRP and donor whole blood (r(s) = 0.22). Significant but irrelevant influences of sex on platelet concentration were found, but no influence of age was detected.

Adult↗

PubMed1986

Cationized ferritin as a platelet-stimulating surface probe. Binding to platelets and effects on platelet function.

Polycationic derivatives of ferritin containing primary amino groups (CFah) or tertiary amino groups (CFdmp) were potent platelet agonists inducing shape change, aggregation and secretion, but also agglutination in the presence of EDTA. Pretreatment of platelets with neuraminidase, PGE1, indomethacin, or creatine kinase/creatine phosphate inhibited CF-induced activation. In contrast, neuraminidase and PGE1 increased the agglutination by CF, indicating an inverse relationship between activation and CF-induced agglutination. At pH 7.4, the cationic charges of CFdmp exceeded those of CFah by a factor of 1.5 and the platelets bound approximately 1.5 times more CFah than CFdmp, suggesting the same number of anionic surface sites for both CF preparations. The capacity of the platelets to bind CF was diminished by 55% at 0 degree C or by 62% after aldehyde fixation and by 13% with PGE1. This suggests that the binding capacity depends on the mobility of the binding sites in the plane of the membrane but is only slightly increased by platelet activation. Binding to fixed or cold platelets approached equilibrium within a few seconds whereas saturation required several minutes at 37 degrees C. Neuraminidase preferentially reduced the slow binding and much less the rapid binding. Since activation by CF developed during seconds, suppressible by a brief treatment with neuraminidase 25 mU/ml, a small portion of neuraminidase-sensitive sites appears to be necessary for CF-induced platelet activation. Full activation and agglutination occurred at CF concentrations far below saturating concentrations. The results show that neither CF-induced activation nor agglutination depend on a simple neutralization of the negative surface charge.

Agglutination↗

PubMed1985

Nomenclature of secreted platelet proteins--report of the Working Party on Secreted Platelet Proteins of the Subcommittee on Platelets.

Standard nomenclature for a number of secreted platelet proteins was agreed upon by The Working Party on Secreted Platelet Proteins of the Subcommittee on Platelets. Platelet factor 4 will continue to be used for the molecule with high heparin affinity, subunit molecular weight of 7780, and the described amino acid sequence. beta-Thromboglobulin will be used to designate beta-Thromboglobulin (81 amino acids/subunit, beta-mobility on cellulose-acetate electrophoresis, pI 7), low-affinity platelet factor 4 (85 amino acids/subunit, gamma-mobility on cellulose-acetate electrophoresis, pI 8), and platelet basic protein (94 amino acids/subunit, pI 10) when these are measured immunologically in plasma, but that thromboglobulin with a superscript designation of the pI should be used when assays are conducted on samples after isoelectric focusing, and a subscript amino-terminal amino acid can be added when a purified protein is described. Thrombospondin will continue to be the designation for the high molecular weight trimer that has previously been called thrombospondin or glycoprotein G. Platelet derived growth factor will be used for the group of closely related proteins of molecular weight about 30,000 and isoelectric point about 10.

Animals↗

PubMed1986

Cryopreservation of dog platelets with dimethyl sulfoxide: therapeutic effectiveness of cryopreserved platelets in the treatment of thrombocytopenic dogs, and the effect of platelet storage at -80 degrees C.

Dog platelets were frozen with 6% dimethyl sulfoxide at 2-3 degrees C per minute in a -80 degrees C mechanical freezer. The frozen platelets were stored at -80 degrees C for as long as 39 months. After storage at -80 degrees C for less than 1 year, platelet in vitro freeze-thaw-wash recovery values were 70%, and in vivo survival values 1 to 2 hr after transfusion were 40% those of fresh platelets. After 2 years or longer storage, in vitro freeze-thaw-wash recovery values were 60%, and in vivo survival values 1 to 2 hr after transfusion were 20% those of fresh platelets. These results indicate that significant deterioration of the dog platelets occurred between the first and second year of storage at -80 degrees C. Platelets that were stored frozen at -80 degrees C for less than 1 year and washed before transfusion into lethally irradiated thrombocytopenic dogs were hemostatically effective.

Animals↗

PubMed1987

Platelet aggregation induced by ether-linked phospholipids. 2. Mechanism of desensitization of rabbit platelets by platelet activating factor and reversibility of inhibitory actions of its antagonists.

Rabbit platelets pretreated with CV-3988 had reduced responsiveness to platelet activating factor(PAF) even after the platelets had been washed with a buffer. This was due to its tight binding to receptor sites for PAF, but not conformational changes of the receptor, because the platelets that were pretreated with CV-3988 and then washed with buffer containing 0.5% bovine serum albumin showed full responsiveness to PAF. In contrast, the reduced responsiveness of PAF-pretreated rabbit platelets was not reversed by washing with buffer containing 0.5% BSA. The PAF-pretreated platelets showed significantly lower responsiveness to 1-O-hexadecyl-2-O-monomethylaminocarbonyl-sn-glycero-3-phosphochol ine (MC-PAF) than to PAF, although MC-PAF had the same potency as PAF on inducing aggregation of normal rabbit platelets by interacting with receptor sites for PAF. These results suggest that the desensitization is accompanied by a decreased affinity of receptor sites for PAF or reduced efficiency in coupling of activated receptor to regulatory protein in plasma membranes rather than loss of receptor sites.

Animals↗

PubMed1983

Comparison of platelet-derived growth factor prepared from release products of fresh platelets and from outdated platelet concentrates.

Platelet-derived growth factor was isolated from the release products of washed, human platelets and from freeze-thawed outdated platelet concentrates. On the basis of sodium dodecyl sulphate polyacrylamide gel electrophoresis and amino acid sequence determination we conclude that platelet derived growth factor released from platelets by the agonist thrombin (EC 3.4.4.13) is structurally similar to that isolated from lysed platelets and from platelet concentrates stored for more than 72 hr at room temperature.

Amino Acid Sequence↗

PubMed2001

Platelet-reactive HLA antibodies associated with low posttransfusion platelet increments:a comparison between the monoclonal antibody-specific immobilization of platelet antigens assay and the lymphocytotoxicity test.

BACKGROUND: Platelet-reactive HLA antibodies are a major reason for low posttransfusion platelet increments. The clinical importance and value of the test systems for their in vitro determination is still controversial. STUDY DESIGN AND METHODS: A prospective analysis of HLA antibodies was performed in sera obtained once a week for at least 4 consecutive weeks from 55 patients (female/male, 28/27; age: median, 49 years; range, 18-69) undergoing intensive chemotherapy and in need of prophylactic platelet transfusions. All sera (n = 330) were analyzed by the monoclonal antibody-specific immobilization of platelet antigens (MAIPA) assay and by the standard lymphocytotoxicity test (LCT). RESULTS: In the MAIPA, 24.5 percent of sera (81/330) obtained from 22 patients contained HLA antibodies. These were detected significantly more often by the MAIPA assay than by the LCT (24.5% vs. 8.2%). Fifty-five sera (20 patients) were positive in the MAIPA assay only. In 15 patients, HLA antibodies were transient. In 3 patients, HLA antibodies were detected earlier by the MAIPA assay than by the LCT. Significantly more sera obtained at the time of low posttransfusion platelet increments were positive in MAIPA alone, rather than in both MAIPA and the LCT (44% vs. 17%). CONCLUSION: The MAIPA assay is more sensitive than the standard LCT in detecting platelet-reactive HLA antibodies. These MAIPA-positive/LCT-negative HLA antibodies affect the posttransfusion platelet increment.

Adolescent↗

PubMed1988

The effect of a dietary supplement of n-3 polyunsaturated fat on platelet lipid composition, platelet function and platelet plasma membrane fluidity in healthy volunteers.

1. Eight healthy male volunteers (aged 22-39 years) supplemented their normal daily diet with 15 g encapsulated fish oil (MaxEPA) for a 6 week period. Fasting blood samples were taken before, at the completion of and 3 months after the period of supplementation. 2. Evaluation of nutrient intakes showed that the intake of n-3 polyunsaturated fatty acids rose significantly (P less than 0.01) during supplementation. This was reflected in changes in the fatty acid composition of platelet phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE) without any changes in phosphatidyl serine, phosphatidyl inositol or sphingomyelin. 3. In both PC and PE there were significant (P less than 0.05) increases in the levels of 18:1n-9 and 20:5n-3 fatty acids and a significant (P less than 0.05) decrease in 20:4n-6 during supplementation. 16:0 rose significantly in PC (P less than 0.05) while in PE, 18:0 fell and both 22:5n-3 and 22:6n-3 rose significantly (P less than 0.05). 4. There were no significant effects of fish-oil supplementation on serum lipids, platelet cholesterol: phospholipid, collagen-induced platelet aggregation or collagen-induced platelet thromboxane B2 production. However, there was a significant correlation (P less than 0.001; r + 0.63) between total phospholipid arachidonic acid and platelet thromboxane production. 5. The fluorescent probe 1,6-diphenyl-1,3,5-hexatriene was used to determine whether fish-oil supplementation altered fluorescence polarization of isolated platelet plasma membrane and, by inference, platelet plasma membrane fluidity. No significant effect of fish-oil supplementation on fluorescence polarization was seen.

Adult↗

PubMed1998

The effects of new platelet inhibitory drug E-5510 on platelet deposition on aortic bifurcation grafts: assessment by indium-111-oxime labeled platelet imaging.

The effects of a recently synthesized anti-platelet aggregation drug (E-5510) on platelet deposition in a knitted Dacron aortic graft underwent preliminary evaluation by In-111 oxime labeled platelet imaging. Seven patients undergoing aortofemoral bypass using this graft for occlusive disease were randomized into two groups: those receiving E-5510 and those receiving no medication. This agent was administered for 17 days postoperatively, and on the 14th day In-111 platelets were injected and images were acquired at 24, 48, and 72 hours. Platelet deposits in the grafts were assessed by the ratios of graft radioactivity to that of the adjacent native iliac arteries. Platelet deposition at the sites of anastomosis and deposition along the entire graft were normalized by initial deposition at 24 hours, and had significantly decreased at 72 hours in the three treated patients, while the normalized deposition increased progressively over time in the remaining four nonmedicated patients. E-5510 seems to have the potential to inhibit excessive platelet deposition on recently implanted grafts.

Aged↗

PubMed1986

Platelet volume, platelet release reaction and platelet response to infused adrenaline are increased in essential hypertension.

Hypertensive men aged 42 (n = 35) were compared to normotensive men of similar age (n = 44). Platelet numbers were similar in the two groups, but hypertensive men had larger venous platelets than the normotensive (7.46 versus 7.12 femtoliter, p = 0.01). Plasma concentration of beta-thromboglobulin (BTG), a marker of platelet release reaction, was increased in arterial blood in hypertension (40 versus 21 micrograms/l, p = 0.02). The normotensive subjects had markedly higher BTG concentration in venous compared to arterial blood (p less than 0.01), but this arterio-venous difference was not present in the hypertensive group. Twelve normotensive subjects received infused saline, which did not induce changes in platelet variables. Adrenaline was infused to 13 hypertensive and 12 normotensive subjects, with dose gradually increasing to 0.04 microgram/kg/min. Platelet count increased in both groups, but significantly more in the hypertensive group. Platelet volume and BTG both increased markedly in the hypertensive group, but not in the normotensive men. Thus, young men with hypertension have increased platelet activity and increased sensitivity to exogenous adrenaline.

Adult↗

PubMed1988

Characterization of a monoclonal antibody ITI-Pl 1 directed against human platelet membrane glycoprotein IIb using extracts of whole platelets and platelet surface and intracellular membranes.

A monoclonal antibody (mAb) termed ITI-Pl 1 has been prepared by the hybridoma procedure. Using immuno-absorption and crossed immunoelectrophoresis of Triton X-100 extracts of untreated and EDTA-treated human platelets it was shown to be directed against the surface membrane glycoprotein IIb (GP IIb). This mAb binds to whole platelets independently of ADP-stimulation and the presence of Ca2+-ions. It saturates at around 870 ng/10(8) cells corresponding to approximately 35,800 molecules/platelet. ITI-Pl 1 did not significantly inhibit GP IIb-IIIa dependent functions such as platelet aggregation or fibrinogen binding. Immunofluorescence could be demonstrated using ITI-Pl 1 and intact normal platelets, but not with platelets from a Glanzmann's thrombasthenia patient. Crossed immuno-electrophoresis with platelet extracts from four different thrombasthenic patients gave a line precipitate in the intermediate gel with 125I-labelled ITI-Pl 1 and autoradiography indicating trace amounts of free GP IIb or the GP IIb-IIIa complex. The epitope on GP IIb detected by ITI-Pl 1 is not destroyed by neuraminidase treatment. Thus the mAb also interacts with neuraminidase-treated GP IIb-IIIa complex in highly purified platelet surface membrane fractions as well as with GP IIb-IIIa from untreated internal membranes isolated by continuous flow electrophoresis.

Animals↗

PubMed1994

Diminished platelet yield and enhanced platelet aggregability in platelet-rich plasma of peripheral vascular disease patients.

Centrifugation of citrated whole blood (cit-WB) for platelet rich plasma (PRP) preparation resulted in a significantly diminished platelet yield compared to when blood was collected in citrate + aspirin (acetylsalicylic acid; ASA) or EDTA anticoagulants in both apparently healthy young subjects and peripheral vascular disease (PVD) patients. The loss in platelets was significantly greater in PVD patients than in young apparently healthy subjects when using cit-WB. Median platelet volume (MePV) of PRP preparations was not different between PVD patients and apparently healthy subjects. The MePV of EDTA-PRP preparations was significantly bigger than cit-PRP and cit + ASA-PRP in both PVD patients and apparently healthy subjects. Citrate and citrate + ASA-PRP of patients was significantly more aggregable to adrenaline. In EDTA-PRP, adrenaline-induced aggregation did not occur. These findings indicate that platelet hyperactivity occurs in PVD even in the presence of ASA. Furthermore, studies involving the use of PRP may not be representative in PVD due to the significant loss of platelets during centrifugation. The methodology described here can be used by those who do not have facilities designed specifically for platelet research.

Aged↗

PubMed1982

Platelet to leukocyte adherence phenomena. (Platelet satellitism) and phagocytosis by neutrophils associated with in vitro platelet dysfunction.

Platelet to leukocyte adhesion phenomena (PLAP) and the phagocytosis of platelets by neutrophils from the EDTA anticoagulated blood samples are described. PLAP was transferable to a normal blood specimen by patient's plasma or serum with or without complement. Further studies revealed in vitro evidence of hereditary platelet dysfunction. In vivo study of platelet survival and in vitro analysis of platelet membrane glycoproteins were normal. We conclude that PLAP can be seen in an asymptomatic individual with in vitro evidence of hereditary platelet dysfunction.

Adolescent↗

PubMed1998

Changes of platelet cytoskeletal proteins following platelet aggregation induced by collagen and platelet membrane glycoprotein in Japanese black cattle with delta-storage pool deficiency.

Five Japanese Black cattle showing the tendency of persistent hemorrhage were diagnosed as delta-storage pool deficiency because of lack of dense bodies in platelets. There was no significant difference in the platelet count, fibrinogen concentration, prothrombin time and activated partial thromboplastin time between the cases and normal control cattle. However, the maximum platelet aggregation rate and the values of myosin in the cytoskeletons during platelet aggregation induced by collagen were significantly lower in the cases compared with those in normal control cattle. The quantities of platelet membrane glycoprotein were in the range of 94-160 kDa and were not different between the cases and control cattle. However, a decrease of thrombospondin in alpha-granules in platelet cytoplasm were suspected in two of the 5 cases.

Animals↗

PubMed1976

Ultrastructure of platelet aggregation in refractory anemia and myelomonocytic leukemia. II. Individual platelet abnormalities: thrombasthenia-like platelets, surface defects, and dissociation phenomena.

Studies of in vitro platelet aggregation were done in five patients with refractory anemia and two with acute myelomonocytic leukemia. The macroscopic results as well as the general ultrastructural findings were reviewed in a companion paper. Electron microscopic analysis of changes in the individual platelets within aggregates revealed a striking heterogeneity, both in the degree of response of each platelet are in the ultrastructural characteristics of the platelet population. Many of the unaggregated platelets had reacted individually, resembling the platelets of patients with Glanzmann's thrombasthenia. There were other abnormalities suggesting the presence of surface defects, such as the presence of areas of obliteration of the interplatelet space (so-called tight connections). One of the most striking findings was a peculiar dissociation between the different components of the aggregation sequence.

Anemia, Aplastic↗

PubMed1990

Filtration of platelet-poor plasma specimens yields platelet-free plasma. Application for batch analysis of beta-thromboglobulin and platelet factor 4.

The authors investigated filtration of platelet-poor plasma through a 0.2-micron filter for the analysis of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) in frozen specimens. Platelets were detected by electron micrograph in the platelet-poor plasma preparation without filtration. No platelets or platelet fragments were seen after filtration. Freezing the unfiltered specimens resulted in a significant increase in the beta-TG and PF4 concentrations, presumably because of release of these proteins from the platelet alpha-granules during freezing and thawing. There was no change in the PF4 levels and only a slight decrease in beta-TG levels after freezing of the filtered specimens. The filtered samples could be frozen for later batch analysis, resulting in considerable cost savings to the laboratory.

Blood Platelets↗

PubMed1982

Comparison between induced platelet aggregation and circulating platelet aggregates as platelet function tests in patients with transient ischemic attacks.

Routine blood analysis, platelet counts, number of circulating platelet aggregates (CPA) and platelet aggregation in vitro against adenosine-diphosphate (ADP), epinephrine and collagene were studied in 45 healthy controls, in 10 hospitalized patients with other neurological diseases than stroke and in 12 patients with transient ischemic attacks (TIA) before and after prophylactive treatment with anticoagulants (AC) or antiplatelet drugs (APD). Except for lower hemoglobin and hematocrit levels in women, sex, smoking, oral contraceptives of pregnancy did not significantly influence the routine blood parameter. Smoking females taking oral contraceptive had an increased number of CPA and the most easily induced aggregation in vitro. Patients with TIA had no significant differences in blood or platelet findings versus the healthy controls (except smoking females on oral contraceptives) or the non-stroke patients, even though individual patients could have high numbers of CPA and an easily induced platelet aggregation in vitro. Treatment with AC did not influence platelet function, whereas APD therapy decreased the number of CPA and inhibited the secondary platelet aggregation in vitro.

Blood Cell Count↗