Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Platelet Function Tests”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed1987

Platelet reactivity in unstable coronary artery disease.

Unstable coronary artery disease (CAD) might be related to obstructions of coronary blood flow by platelet aggregates. In 121 men and 43 women admitted to the coronary care unit with suspected unstable CAD, blood samples for tests of platelet function were obtained within 24 hours after admission. Platelet reactivity was tested in vitro in platelet rich plasma as the aggregability towards ADP 1 microM and collagen 1 mg/ml and as the sensitivity to prostacyclin (PSP). The levels of beta-thromboglobulin and platelet factor 4 were determined ex vivo in platelet poor plasma. Patients who developed a nontransmural myocardial infarction (n = 39) or had signs of myocardial ischemia at an exercise test performed within a week (n = 39) were considered to have unstable CAD while patients without signs of ischemia constituted the control group. In the acute phase the PSP was reduced in patients with unstable CAD without any difference between genders. The aggregability towards ADP was higher in women than men but otherwise there were no differences between groups or sexes in any other test in the acute phase. After 12 months there were no differences in PSP between the groups but women had a lower PSP than men. Thus, in the acute phase of unstable CAD, the platelet sensitivity to the inhibitory effects of prostacyclin was reduced which might contribute to the risk for further platelet aggregation, coronary occlusion and myocardial infarction.

Acute Disease↗
PubMed1993

Effect of diltiazem and low-dose aspirin on platelet aggregation and ATP release induced by paired agonists.

The authors studied the effects of diltiazem, administered alone and together with low-dose aspirin, on the platelet response to paired agonists. After a baseline period, 25 healthy volunteers were given oral diltiazem for 1 week (120, 240, or 360 mg/day), and then crossed over randomly between 1 week on diltiazem plus aspirin (81 mg/day), and 1 week on aspirin (81 mg/day) alone. Platelet function was tested on 2 consecutive days in each period. Synergistic platelet aggregation and ATP release were obtained at baseline using a subthreshold concentration of arachidonic acid combined with platelet activating factor, ADP, or epinephrine. Diltiazem resulted in significant decrease from baseline in platelet aggregation and ATP release using the arachidonic acid-epinephrine combination (35% and 40% decrease, respectively, p < 0.01) and a significant decrease in aggregation using the arachidonic acid-ADP combination (22% decrease, p < 0.01). The effects were neither dose-related, nor accompanied by any significant change in serum thromboxane B2 levels or bleeding times. There was no significant difference between the effects of aspirin alone and aspirin plus diltiazem on the synergistic platelet aggregation and ATP release induced by the paired agonists, or on thromboxane B2 levels or bleeding times. Diltiazem administered in vivo partially inhibits the synergistic platelet aggregation and ATP release induced by paired agonists; however, in contrast to a previous in vitro study it does not potentiate the platelet-inhibitory effect of aspirin.

Adenosine Diphosphate↗
PubMed1984

A quick method for screening platelet dysfunctions using the whole blood lumi-aggregometer.

Patients who present with a clinical history suggesting a bleeding disorder are often tested initially for a clotting defect rather than for platelet dysfunction, due to the length of time necessary to complete a platelet function study in platelet-rich plasma. We have developed a sensitive method for measuring platelet aggregation and release of ATP employing the Whole Blood Lumi -Aggregometer. This method makes it possible to quickly detect patients who require further study for possible platelet function disorders such as cyclooxygenase deficiency, storage-pool defect, thrombasthenia, and von Willebrand's disease. The results obtained with this electrical impedance instrument do not differ from those obtained with the conventional optical method. However, it is now possible to recognize a platelet function defect within 30 min of obtaining a 5 ml sample of citrated whole blood. Further, platelets of unusual size or density are not lost to testing through centrifugation.

Adenosine Triphosphate↗
PubMed2005

Platelet dysfunction in primary thrombocythemia using the platelet function analyzer, PFA-100.

We measured platelet function by standard aggregometric tests and by the PFA-100 (Dade Behring, Newark, DE) in samples from 55 patients with primary thrombocythemia (PT) and 26 healthy volunteers. Platelet function was evaluated in platelet-rich plasma by aggregation tests. PFA-100 studies (closure time) were performed in citrated whole blood using collagen-adenosine diphosphate (ADP) and collagen-epinephrine cartridges. Plasma levels of von Willebrand factor (vWF) also were measured. The mean +/- SD closure time for patients vs volunteers for the collagen-epinephrine cartridge was prolonged (210.8 +/- 62.2 vs 118.1 +/- 19.6 seconds; P < .001); results were abnormal for 38 patients (69%). Results with the collagen-ADP cartridge also were abnormal in patients (134.3 +/- 58.4 seconds) vs volunteers (87.3 +/- 15.6 seconds; P < .001); closure time was prolonged in 23 patients (42%). A decreased response to epinephrine (38.4% +/- 34.2% vs 82.5% +/- 10.3%; P < .001), the main defect detected by platelet aggregation tests, affected 32 patients (58%). Platelet response to collagen also was abnormal (52.0% +/- 34.6% vs 86.0% +/- 10.1%; P < .01) but affected only 21 patients (38%). vWF levels for patients were normal. The results seem to confirm that platelet function in patients with PT is abnormal and show that platelet function can be assessed by an easy, reproducible, and sensitive method, the PFA-100. Closure time usually was prolonged; this feature could be applied in the diagnosis of PT.

Adult↗
PubMed2003

Does the platelet function analyser (PFA-100) predict blood loss after cardiopulmonary bypass?

BACKGROUND: This study was designed to determine if a new point-of-care test (PFA-100) platelet function analyser) that assesses platelet function predicts blood loss after cardiac surgery. METHODS: and results. Blood samples from 70 patients were drawn before and after cardiopulmonary bypass (CPB) for PFA-100 measurements. The system consists of a cartridge in which a membrane and an aperture are coated with either collagen/adenosine-5'-diphosphate or collagen/epinephrine. The instrument determines the time required for full occlusion of the aperture (closure time). We observed a weak correlation between pre-CPB collagen/epinephrine closure time and second-hour mediastinal blood loss (r=0.34, P=0.01). The sensitivity and positive predictive value of the PFA-100 measurements were comparable to platelet count for predicting excessive bleeding after CPB (75 and 27% vs 100 and 25%, respectively). CONCLUSIONS: The PFA-100 is a logical test for detecting patients who could have excessive bleeding after CPB. However, the PFA-100 was not able to separate patients at low risk of subsequent bleeding from those who had substantial bleeding.

Blood Platelet Disorders↗
PubMed1990

[Comparison of methods of cryopreservation of blood platelets].

In the submitted paper the author compares two different methods of cryopreservation of thrombocyte concentrates by means of in vitro tests with the aim to find under local conditions a suitable method of cryopreservation of platelets suited for practical use. Thrombocyte concentrates were preserved by non-programmed deep freezing at -80 degrees C with storage of platelets at the same temperature and programmed deep freezing up to -100 degrees C with subsequent storage of platelets in liquid nitrogen vapours. As a cryoprotective substance DMSO in a final 5% concentration was used. Between the two cryopreservation methods no significant differences were found as regards yield of platelets or in functional tests. For cryopreservation of platelets it will be useful to use the method of non-programmed freezing at -80 degrees C because it is simple and feasible. The process of cryopreservation proper of thrombocytes, incl. washing, did not lead to a marked drop in the number of platelets, as compared with values before freezing.

Blood Platelets↗
PubMed2002

Functional redundancy of Rab27 proteins and the pathogenesis of Griscelli syndrome.

Griscelli syndrome (GS) patients and the corresponding mouse model ashen exhibit defects mainly in two types of lysosome-related organelles, melanosomes in melanocytes and lytic granules in CTLs. This disease is caused by loss-of-function mutations in RAB27A, which encodes 1 of the 60 known Rab GTPases, critical regulators of vesicular transport. Here we present evidence that Rab27a function can be compensated by a closely related protein, Rab27b. Rab27b is expressed in platelets and other tissues but not in melanocytes or CTLs. Morphological and functional tests in platelets derived from ashen mice are all within normal limits. Both Rab27a and Rab27b are found associated with the limiting membrane of platelet-dense granules and to a lesser degree with alpha-granules. Ubiquitous transgenic expression of Rab27a or Rab27b rescues ashen coat color, and melanocytes derived from transgenic mice exhibit widespread peripheral distribution of melanosomes instead of the perinuclear clumping observed in ashen melanocytes. Finally, transient expression in ashen melanocytes of Rab27a or Rab27b, but not other Rab's, restores peripheral distribution of melanosomes. Our data suggest that Rab27b is functionally redundant with Rab27a and that the pathogenesis of GS is determined by the relative expression of Rab27a and Rab27b in specialized cell types.

Animals↗
PubMed1981

[Retinal vascular changes and haemostatic function in young patients (author's transl)].

Haemostatic function was studied in 40 patients between one and 12 months from the occurrence of retinal vein occlusion (RVO); 25 patients aged 40 years, or less and 15 were more than 45 years old. The following tests were performed : plasma beta-thromboglobuline (beta-TG) fibrinopeptide A (FpA), PTT, spontaneous in vitro platelet aggregation (SpA), circulating platelet aggregates (CPA), platelet retention (PR) to glass beads, serum thromboxane B2 (TxB2). In the group of older patients, there was a significant increase of beta-TG, FpA, PR, SPA, TxB2, and a reduction in the PTT. CPA was not significantly changed. In the group of younger patients (less than 40 yrs) only FpA and beta TG levels showed significant differences from the control group of age-matched healthy subjects. These findings suggest that the alterations present in older patients are likely to be secondary to generalized vascular damage, whereas a state of activation of the coagulation system appears to be present in younger patients with RVO.

Adult↗
PubMed1985

The effect of a prostaglandin I2 analogue (OP-41483) on renal function in burned rabbits.

It is known that the number of platelets decreases after burn injury. However, the mechanism of such a decrease and its influence on systemic organs have not been fully elucidated. In this study, we evaluated the efficacy of OP-41483 (a derivative of the prostaglandin I2 (PGI2) in burned rabbits with special reference to its association with renal function. Full thickness skin loss burns, covering 35 per cent of the total body surface area, were experimentally produced on the back of rabbits. Among the following groups of rabbits (six rabbits each), the time courses of renal function and platelet function were compared; Group I (no treatment), Group II (fluid therapy only), Group III (treated with OP-41483 + fluid therapy; IIIa: 50 ng/kg/min, IIIb: 75 ng/kg/min, IIIc: 100 ng/kg/min). The results show that in Group I, all rabbits died after 8 h. Renal function tests in this group showed a decrease in creatinine clearance and increases in FENa and CH2O. Such changes were improved in Groups IIIb, IIIa and II (in order of the degree of improvement). Group IIIc showed no improvement. As for the platelets the decrease in platelets was the smallest in Group IIIb, where platelets showed no decrease until 8 h after injury and the fibrinogen concentration increased. No improvement was found in Group IIIc by our tests, presumably owing to an overdose of OP-41483. The optimal dose of OP-41483 for improving the renal function of burned rabbits was 75 ng/kg/min in our study.

Animals↗
PubMed2002

In vitro tests for assessing heparin-induced thrombocytopenia in patients after elective hip replacement. A medico-economical evaluation.

OBJECTIVES: Considering the previously published incidences of heparin-induced thrombocytopenia (HIT) in patients receiving a thromboprophylactic therapy, the role of the hemostasis laboratory is essential in making a clinical decision. The purpose of this project was to compare the strategies of diagnosis and associated care of patients with suspected HIT after elective hip replacement using platelet aggregation assay, carbon 14-serotonin release, and "doing nothing." METHODS: The authors used an incremental cost-effectiveness analysis based on data extracted from the literature. The effectiveness of the strategies was represented by the number of deep venous thromboses prevented. Cost data were collected from the observation of biological and medical practice at Edouard Herriot University Hospital, Lyon, France, in 1999. RESULTS: In comparison with the strategies of doing nothing using no biological test for diagnosis, and clinical care of HIT-suspected patients, the strategy using platelet aggregation test was more expensive and less effective. With respect to the strategy using carbon 14-serotonin release assay, the incremental cost-effectiveness ratio, expressed as U.S. dollars per deep venous thrombosis prevented, reached $200,000, with a marginal effectiveness of eight deep venous thromboses prevented for 10,000 HIT-suspected patients. CONCLUSION: This study suggests that clinical hemostasis laboratories might consider replacing the platelet aggregation test with the carbon 14-serotonin release assay or should use another functional assay such as the flow cytometric assay for the diagnosis and care of patients with suspected HIT.

Anticoagulants↗
PubMed2001

[Effects of lysine clonixinate on platelet function. Comparison with other non-steroidal anti-inflammatory agents].

One of the mechanisms of action of non steroid antiinflammatory drugs (NSAIDs) consists of inhibition of prostaglandin synthesis. This explains many of the pharmacological effects and adverse events observed in medical practice. Administration of NSAIDs to patients with hemostatic disorders or perioperative conditions entails the risk of bleeding due to inhibition of platelet function. This study deals with platelet changes induced by lysine clonixinate vs diclofenac, ibuprofen and aspirin in classical tests such as platelet count, platelet factor 3 (PF3) activity and platelet aggregation with various inductors and more recent procedures such as P-selectin measurement by flow cytometry. Unlike control drugs, lysine clonixinate did not induce changes in platelet count or function when administered to healthy volunteers at the commonly used therapeutic doses.

Adult↗