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PubMed2006

Suitability of measurement of swirling as a marker of platelet shape change in concentrates stored for transfusion.

Platelet discoid shape is known to correlate with in vivo viability after transfusion. Measurement of shape change requires invasive sampling and laborious assays, which is difficult to perform in a blood transfusion center as a routine test for quality control of stored platelets. The objective of this study was to establish suitability of swirling assessment in stored platelet suspension as a routine test for quality check, by comparing platelet shape change measurement carried out in parallel. The study was done in two types of bags obtained from different manufactures (Groups 1 and 2). Platelet concentrates (PC) were stored for 120 h and samples drawn at 24-h intervals, optical analysis at 540 nm was carried out to quantify shape change in response to an agonist adenosine diphosphate (ADP). The same bags were subjected to swirling assessment, by two blood bank personnel independently and graded as positive (+, ++, +++) or as negative, based on the silky appearance of the suspension. Swirling negative platelets were prepared by storing platelets at 4 degrees C for 24 h and were compared with swirling positive platelets. Other parameters studied in the samples drawn at 24-h intervals were platelet count, mean platelet volume, and blood gases. Swirling assessment results correlated well with shape change measurement at each study period with a P value significant at 0.02 and 0.04 for group 1 and 2 bags, respectively. In the negative swirling controls, extent of shape change was lower than the extent in test bags, showing reduced capacity to respond to ADP at 4 degrees C. The results of the study indicate that by simple swirling measurements, stored PC can be monitored for loss of discoid shape before they are transfused. Gas tension and pH were with in permissible limits. Therefore, inspection of swirling can be a reliable method of quality control as it correlates with platelet function. The platelets that retain the discoid shape in vitro at the time of transfusion are expected to be functional in vivo.

Biomarkers↗
PubMed2001

Small peptide GP IIb/IIIa receptor inhibitors as upstream therapy in non-ST-segment elevation acute coronary syndromes: results of the PURSUIT, PRISM, PRISM-PLUS, TACTICS, and PARAGON trials.

The primary pathophysiologic mechanism underlying all non-ST-segment elevation acute coronary syndromes (NSTE ACS) is the formation of platelet-rich coronary thrombi in response to spontaneous or intervention-induced endothelial damage with exposure of subendothelial substrates. Antagonists of the glycoprotein (GP) IIb/IIIa receptor ameliorate this process by blocking the final common pathway for platelet aggregation. Based upon collective data in over 24,000 patients, clinical trials have demonstrated that treatment of NSTE ACS patients with GP IIb/IIIa agents results in an approximate 12% relative risk reduction in the incidence of death or myocardial infarction at 30 days. The magnitude of this clinical benefit is increased in patients who are troponin-positive and who are referred for early percutaneous intervention. Potential benefits of GP IIb/IIIa inhibitor use must be weighed against an increased risk of bleeding. Ongoing controversies exist concerning the relative efficacy of different GP IIb/IIIa antagonists, the accurate use of platelet function tests to define safe and efficacious drug dosing, the adjunctive use of additional anti-thrombotic agents, and the optimal timing of upstream therapy before diagnostic cardiac catheterization and revascularization.

Acetates↗
PubMed2004

The effect of ASA on platelet activation during apheresis and on in-vitro properties of stored platelet concentrates.

BACKGROUND: Preventing the activation of PLTs may ameliorate (or mitigate) the PLT storage lesion (PSL), which encloses all structural and biochemical changes caused by collection, processing, and storage of PLT concentrates (PCs). Partial inhibition of PLT function due to ingestion of aspirin (ASA) by blood donors reduces the functional activity of the collected PLTs, however, by preventing premature PLT activation, it might reduce the PSL as well. STUDY DESIGN AND METHODS: In a randomized crossover study, 10 healthy donors donated two single-donor PCs (SDPCs) each, taking 500 mg ASA 12 hours before one of the aphereses (Group A) and taking no medication before the other donation (Group B). In-vitro tests of PLT function were performed in donors before and after apheresis and in SDPCs during storage (Days 1, 3, and 5). RESULTS: ASA ingestion resulted in a significant decrease of induced PLT aggregation in donors (p < 0.005) and SDPCs on Day 1 (p < 0.01). TRAP-6-induced expression of p-selectin (CD62p) was significantly reduced in Group A SDPCs only on Day 1 (p < 0.02). There were no significant differences of in-vitro function (LDH, lactate, pH, morphology score, CD62p expression, fibrinogen binding) between Group A and B (SDPCs and donors). Apheresis did not result in a significant activation of PLTs in donors or SDPCs. CONCLUSIONS: These limited data do not show a detectable beneficial effect of ASA ingestion on the PSL but do suggest that ASA ingestion before apheresis may not be detrimental to the clinical effectiveness of the stored product.

Adenosine Diphosphate↗
PubMed1992

In vitro inhibition of blood coagulation by tripeptide aldehydes--a retrospective screening study focused on the stable D-MePhe-Pro-Arg-H.H2SO4.

A series of peptide aldehydes synthetized in our institute during the last 15 years were screened to detect their inhibitory effect on blood coagulation. Simple conventional clotting assays, platelet function tests and fibrinolytic methods were used to evaluate the inhibitory potency of the compounds in complex clotting systems as well as their supposed antifibrinolytic effect in vitro. Special attention was paid to the possible interactions with blood cells and plasma proteins, and to the functional stability of the inhibitors in several tissue homogenates. D-Phe-Pro-Arg-H (GYKI-14166, RGH-2958), Boc-D-Phe-Pro-Arg-H (GYKI-14451) and D-MePhe-Pro-Arg-H (GYKI-14766) were found to be the most potent inhibitors. The peptide aldehydes via formation of reversible complexes with thrombin impede the enzyme to react with the coagulation factors, platelet membrane and vessel wall. The compounds inhibit platelet aggregation induced by thrombin specifically without changing the sensitivity of platelets to other inducers. D-Phe-Pro-Arg-H and D-MePhe-Pro-Arg-H showed no antifibrinolytic effect. D-MePhe-Pro-Arg-H and Boc-D-Phe-Pro-Arg-H proved to be stable in dry state for years and in solution at room temperature for several days. The anticoagulant activity of the compounds was declared in NIH antithrombin units.

Animals↗
PubMed1974

Essential thrombocythaemia and peripheral gangrene.

Six patients are described in whom gangrene of one or more toes occurred as the presenting feature of essential thrombocythaemia. Spontaneous platelet aggregation was observed in platelet-rich plasma from four patients and platelet aggregation after the addition of adenosine diphosphate and collagen was highly abnormal in samples from all six. All of the patients described dramatic relief of pain within six hours of ingestion of aspirin and this coincided with disappearance of the spontaneous platelet aggregation and collagen-induced platelet aggregation. Treatment with phosphorus-32 corrected the platelet count and there were no further recurrences of peripheral vascular disease. Platelet function tests performed at the time all gave normal results. It is concluded that essential thrombocythaemia is an important and treatable cause of peripheral vascular disease.

Adenosine Diphosphate↗
PubMed1998

Cerebral vascular accidents in young patients with essential thrombocythemia: relation with other known cardiovascular risk factors.

BACKGROUND AND PURPOSE: Since the advent of routine automated blood cell counts, an increased platelet count often is detected fortuitously in asymptomatic individuals. In the past, essential thrombocythemia (ET) was thought to be linked to an increase incidence of hemorrhagic complications, whereas thrombosis is now considered more frequently. Actually, the risk of thrombosis cannot be predicted in an asymptomatic patient with essential thrombocythemia. PATIENTS AND METHODS: A total of 41 young patients (age range, 18 to 45 years) affected by ET and diagnosed in agreement with the Polycythemia Vera Study Group criteria are reported. Common risk factors, such as hypertension, smoke, obesity, dyslipidemia, and diabetes, have been registered. Particular attention has been given to cerebral vascular accidents (CVA) both of the arterial and venous systems. Platelet number, platelet serotonin content, and platelet aggregation under collagen, adenosine diphosphate (ADP), and adrenalin stimuli were evaluated. RESULTS: Nine out of the 41 patients affected by ET had CVAs, four of which occurred in the venous system. No difference in platelet function tests has been observed between patients with or without CVA. Six out of the 9 patients with ET and CVA had at least one atherosclerotic risk factor: four were heavy smokers, one had hypertension, and one had hypertension and obesity. CONCLUSIONS: Cerebral vascular accidents are confirmed to be frequent in patients with essential thrombocythemia, even at a young age. However, the presence of at least one atherosclerotic risk factor associated with increased platelet number seems to favor thrombotic complications. In particular, cigarette smoking seems to be related to arterial CVAs in essential thrombocythemia.

Adult↗
PubMed1977

Inherited platelet abnormalities associated with low factor VIII activity in the same family.

Six of eight examined members belonging to two generations of the same (NEG-TUR) family were shown to have functional changes in platelets and/or a moderate decrease of factor VIII activity (FVIII:C) in plasma, with normal values of factor VIII-related antigen (VIII R:AG). Platelet defects (mainly a reduced PF3 availability, present in five patients) and factor VIII decrease were combined differently in individual members. Only two male members with both the PF 3 and FVIII:C defects had moderate haemorrhagic symptoms following traumatic injuries. One of them had also an absent adhesiveness to glass, the other one an absent adhesiveness to collagen and a reduced platelet aggregation by ADP and by collagen. Bleeding time, platelet function tests (in the other members), and routine coagulation tests were within normal range; ristocetin aggregation was also normal in all members. We think that two inherited defects, a mild haemophilia A and a "sui generis" thrombocytopathy, co-exist in this family.

Adolescent↗
PubMed2005

Investigation of the PADA as a method for monitoring GPIIb/IIIa inhibitors and other antiplatelet agents.

Treatment with glycoprotein (GP) IIb/IIIa inhibitors in combination with aspirin and clopidogrel have become essential therapeutic strategies during invasive procedures and coronary events. However, the ideal monitoring test for the effects of these treatments is still missing. Therefore, we investigated the new Platelet Adhesion Assay (PADA) for its sensitivity in characterizing antiplatelet therapy. Five healthy volunteers were studied before and after a single dose of aspirin (500 mg). Samples were spiked in vitro with increasing doses of abciximab (0, 0.25, 1, 3 microg/mL), eptifibatide (0, 0.25, 1, 2 microg/mL), and AR-C 69931 MX (1 microg/mL) in citrated and hirudinized whole blood. The adhesion index (AI), as the characteristic parameter of the PADA test, decreased in a dose-dependent fashion for abciximab and eptifibatide. Variable effects between the different anticoagulants were shown for eptifibatide. Aspirin showed no additional effect, while inhibition by AR-C 69931 MX was demonstrated in hirudinized blood only. We concluded that different levels of GPIIb/IIIa inhibitors and adenosine diphosphate-receptor inhibition could be assessed with the PADA test, although different anticoagulants led to different results. The suitability of this test for daily use will have to be elucidated in further patient studies.

Abciximab↗
PubMed1997

Platelet function in septic multiple organ dysfunction syndrome.

OBJECTIVE: Altered platelet function plays a role in the pathophysiology of multiple organ failure in sepsis. The purpose of the present study was to evaluate various aspects of platelet adhesive function in septic patients and its putative relevance for prognosis. DESIGN: Prospective clinical study. SETTING: Intensive Care Unit of the University Hospital. PATIENTS AND METHODS: A total of 41 patients admitted to the medical Intensive Care Unit were studied. On the day of admission, patients were evaluated by intensive care scoring systems (Elebute, APACHE II) to assess the severity of sepsis and multiple organ dysfunction syndrome (MODS), and platelet function tests were performed. All patients were observed for 28 days to assess their clinical outcomes. Eleven patients revealed septicemia without MODS (Elebute > or = 12, APACHE II < 20) and 20 septic patients suffered from MODS (Elebute > or = 12, APACHE II > or = 20). Ten non-septic patients without MODS served as a control group (Elebute < 12, APACHE II < 20). Flow cytometric determination of the activated fibrinogen (fg) receptor GPIIb-IIIa and as well as thrombospondin (TSP) on platelets and platelet-neutrophil adhesion (CD 41 immunofluorescence) ex vivo was performed using monoclonal antibodies. The effect of plasma obtained from patients on normal platelet aggregation in vitro, and adhesion to cultured endothelial cells was evaluated. RESULTS: The surface expression of TSP on platelets was increased in septic patients with MODS compared to controls (p < 0.03). Platelet-neutrophil adhesion was not significantly altered in septicemia (p < 0.09) but decreased significantly in the presence of MODS (p < 0.05) when compared to controls. Logistic regression analysis showed that platelet-neutrophil adhesion was an independent predictor for poor clinical outcome (p < 0.01). Plasma from septic patients sensitized normal platelets to hyperaggregate and to adhere to cultured endothelium (p < 0.01). CONCLUSION: In septic patients platelets become activated and are hyperadhesive to other vascular cells including neutrophils and endothelium. This may induce sequestration of platelets and microcirculatory arrest, thus the development of MODS.

APACHE↗
PubMed1990

Platelet membrane defects in fawn hooded bleeder rats.

An inbred strain of fawn hooded rats with a congenital platelet defect shows a marked bleeding tendency with prolonged bleeding time. This haemorrhagic disorder has been exclusively related to a deficiency of nucleotides in platelet dense granules. When tested in cell electrophoresis platelets from fawn hooded bleeder rats showed a significantly lower electrophoretic mobility than normal rat platelets. Subsequent studies on the platelet membrane protein pattern by high resolution two-dimensional gel electrophoresis revealed the deficiency of a membrane glycoprotein (apparent molecular mass 90.000, isoelectric point 5.6), which is detectable in normal rat platelets after surface labeling by periodate-tritiated sodium borohydride. It seems likely, that this glycoprotein defect contributes at least partially to the disorder of platelet function in fawn hooded bleeder rats.

Animals↗
PubMed2002

Evaluation assays measuring platelet kinetics in bone marrow and peripheral blood. An overview.

Platelets play an important role in haemostasis and thrombosis. For an understanding of the pathophysiology and treatment of thrombocytopenia, it is not sufficient to measure only the platelet count. Platelet kinetic parameters, such as platelet survival and turnover, might be useful because many thrombocytopenia related disorders result from the interaction between production, utilization or destruction, and sequestration of platelets. Therefore, measuring platelet turnover with radiolabelled platelets could be a sensitive and qualitative tool for clinicians. However, the method does not enjoy widespread use because it has some serious drawbacks, such as the problems associated with the manipulation of blood and platelets, and the use of radioactivity. Recently, other useful assays for measuring platelet fluxes have been described in the literature, including plasma thrombopoietin and glycocalicin. In this review, these new tests will be described, compared with the classical method using radiolabelled platelets, and finally evaluated for their usefulness in clinical practice.

Biomarkers↗
PubMedDate not supplied

The effect of plasticizers of plastic material bags on biochemical and morphological changes of morphotic blood elements.

The concentration of di-2-ethylhexylphthalate (DEHP) was determined in whole blood, packed red cells and plasma of the blood collected into blood plastic bags manufactured by McGaw, Biotest or Polfa, in samples withdrawn immediately after collection and 1, 2 and 3 weeks later. ATPase activity and electrolyte (K+, Na+, Mg++) composition of erythrocytes were tested and possible morphological changes were inspected in phase-contrast microscope. Platelet aggregation induced by ADP, collagen and adrenaline was also investigated. Blood stored in glass bottles served as a standard. The DEPH concentrations were similar in samples contained in various bags. Maximum DEPH concentration in the whole blood, after 3 weeks of storage, attained 52 microgram/cm3. ATP-ase activity was more rapidly depressed in the blood kept in bags instead of glass bottles. Erythrocyte morphology and results of platelet function tests remained unaffected.

Adult↗
PubMed1989

True anemia: incidence and significance in the elderly.

The incidence of anemia increases as humans age, but in healthy aging individuals followed longitudinally, significant anemia does not develop in the absence of disease. Mild lymphopenia, as well as abnormal platelet function tests and increased coagulability when measured in vitro, also tend to develop in aging individuals. Hematologic neoplasia in the elderly behaves very similarly to the way it does in young individuals, but elderly individuals with hematologic neoplasms have a poor response to therapy.

Aged↗
PubMed1992

Glycoproteins Ib and IIb/IIIa in the quality assessment of platelet concentrates during storage.

We have previously shown that levels of soluble glycocalicin (GC) in plasma supernatants derived from units of platelet concentrates (PC) increase progressively during storage. We now report further studies which show that the levels of both microparticle-bound and soluble GC in PC during storage are influenced by exposure of PC samples to EDTA and treatment of PC packs with ultraviolet B (UVB) irradiation. EDTA leads to a significant increase in the release of microvesicle-bound and soluble GC, while UVB irradiation leads to a dose- and rate-dependent increase in GC release. Paradoxically, UVB leads to an unexpected decrease in supernatant levels of von Willebrand factor (vWf) during storage which contrasts with its increase in untreated, stored PC. Moreover, an increase in GC release during storage is associated with a corresponding decrease in platelet size as determined by measurement of mean platelet volume (MPV) in citrated PC. The GC release is significantly correlated with standard platelet functional tests and other new generation tests such as dMPV and supernatant levels of vWf. In addition, preliminary results show the presence of microparticle-bound and soluble glycoprotein (Gp) IIb/IIIa in the supernatant plasma of stored PC. Our results suggest that supernatant levels of GpIb, GpIIb/IIIa, and vWf, together with alteration in MPV, provide essential new informative parameters for quality assessment of PC.

Blood Platelets↗
PubMed1986

Hypercoagulable state induced by cytostatic drugs in stage II breast cancer patients.

An increased incidence of thromboembolic complications occurring in cancer patients during chemotherapy was recently reported. In view of this report, a study in 49 patients receiving adjuvant chemotherapy for Stage II breast cancer was begun in order to determine the effect of antineoplastic drugs on coagulation factors and platelet function. Among the coagulation factors, a significant decrease of thrombin time and partial prothrombin time was observed, whereas platelet function tests were unchanged. This finding suggests a trend towards hypercoagulability induced by chemotherapy. This effect should be considered when chemotherapy is employed in advanced cancer patients at high risk for thrombosis.

Adult↗
PubMed2004

Point-of-care determination of baseline platelet function as a predictor of clinical outcomes in patients who present to the emergency department with chest pain.

BACKGROUND: Increased platelet reactivity can identify patients at high risk for thrombotic events, but its clinical use has been impractical due to technical limitations. The purpose of the present study is to determine if a point-of-care measurement of platelet function in patients presenting to an emergency room with chest pain can identify those at high risk of adverse cardiac events. METHODS: Platelet function was measured using the Ultegra-RPFA in 201 patients presenting to the emergency department with the primary complaint of chest pain and either known coronary disease or at least one cardiac risk factor. The primary endpoint was any major adverse cardiac events (MACE) [cardiac death, myocardial infarction (MI), re-admission for coronary revascularization] 6 months post-enrollment. RESULTS: Platelet function at baseline ranged from 44 to 315 platelet activation units (PAU) (mean 175+/-6). Seventy-six patients experienced MACE (37.8%) by 6 months post-enrollment. Mean PAU was significantly lower in the group experiencing MACE (166+/-9 vs. 181+/-9; p=0.026). By univariate analysis, admission PAU was a significant predictor of MACE at 6 months (p=0.028). However, when adjusted for age, gender, cardiac risk factors, and a history of coronary artery disease (CAD) using multivariate logistic regression analysis, PAU was no longer significantly predictive of MACE (p=0.268). CONCLUSIONS: Point-of-care testing of platelet function deserves further study for risk assessment and individualized therapy in the future.

Aged↗
PubMed1993

[Effect of preparation and preservation modality on thrombocyte quality].

In patients with acute leukemia, chemotherapy leads to subsequent aplasia-associated thrombocytopenia requiring the substitution of platelets to avoid and treat bleeding complications. A multitude of tests to assess the quality of platelet concentrates is available to date. In this study, we investigated the quality of platelet concentrates prepared by two different methods, preparation from platelet-rich plasma versus preparation from buffy coat, and stored under varying conditions, namely horizontal versus vertical rotation, by measuring the binding rate of corresponding antibodies to platelet membrane glycoproteins GPIb, GPIIb-IIIa, GPIa-IIa and GPIV using flow cytometry. Expression of platelet surface antigens was well maintained during platelet preparation and storage for 7 days. Preparation and storage modalities showed no significant effect on the expression of membrane glycoproteins. These results indicate that platelet function as represented by antibody binding is well maintained during platelet preparation and storage leading to sufficient hemostasis following transfusion.

Acute Disease↗