BACKGROUND

Thrombi form mainly in the left rather than the right atria of patients with atrial fibrillation (AF), the reason of this predilection being unknown.

OBJECTIVE

The purpose of this study was to investigate whether atrial-specific differences in endothelial damage, leukocyte activation, platelet stimulation, and tissue factor activity occur in patients with AF.

METHODS

Twenty-two patients (16 men, 6 women; age 56 ± 8 years; 16 paroxysmal AF, 6 persistent AF) with AF undergoing pulmonary vein isolation were investigated. Blood samples from the left and the right atrium were obtained at the start of the procedure. Microparticles (MPs) released by apoptotic/stimulated cells were measured by capture assays. Their procoagulant abilities were quantified by functional prothrombinase and tissue factor assays and their cellular origin were determined (endothelium, platelet, leukocyte). Platelet reactivity was evaluated by whole blood flow cytometry for expression of platelet P-selectin (CD62P), active glycoprotein IIb/IIIa receptor (PAC-1). Platelet aggregation was evaluated using ADP, TRAP and collagen-induced whole blood aggregometry.

RESULTS

There were no atrial-specific differences in the levels of total procoagulant MPs, leukocyte-derived-MPs or platelet-derived MPs. Conversely, endothelial-derived MPs and tissue factor activity and collagen-induced platelet aggregation were slightly elevated in the right atrium (P < 0.05).

CONCLUSIONS

Our data show no evidence for increased thrombogenic status in the left atrium that would account for its greater propensity for thrombus formation in patients with AF.

BACKGROUND

1) To investigate the expression of platelet collagen receptor glycoprotein VI (GPVI) on the surface of platelets in patients with coronary heart disease (CHD). 2) To investigate the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on the surface of endothelial cells after exposure to subjects' platelets.

METHODS

Platelets were extracted from blood samples of 97 subjects including 43 with acute coronary syndrome (ACS), 21 with stable angina pectoris (SAP), and 33 serving as controls in which CHD was excluded. Using flow cytometry, we measured the expression of GPVI and platelet degranulation markers CD62P and CD63. In addition we quantified expression of endothelial cell ICAM-1 and VCAM-1.

RESULTS

A higher expression of platelet GPVI was observed in ACS compared with SAP and control groups. The expression level of platelet GPVI significantly correlated with CD62P and CD63 in the CHD population (r = 0.713 and 0.615, both p < 0.01). Significantly higher ICAM-1 expression was observed in endothelial cells after interaction with platelets from the ACS population. In the CHD subjects, the surface expression of platelet GPVI correlated with the level of ICAM-1 in endothelial cells (r = 0.371, p < 0.05).

CONCLUSIONS

Platelet GPVI associated with platelet activation and endothelial inflammation is a vital index for predicting CHD occurrence and severity.

Platelets play an important part in normal haemostasis, and are likely to be involved in the thromboembolism seen in the primary antiphospholipid syndrome (PAPS). Evidence exists for platelet activation in this disorder, and new flow cytometric techniques have made it possible to detect low levels of activation. We have previously studied the expression of the platelet activation markers CD62p and CD63, percentage of reticulated platelets, and levels of soluble P-selectin in a group of PAPS patients. Median platelet CD63 expression and plasma soluble P-selectin levels were significantly increased in PAPS patients compared to a group of controls; there was no difference in reticulated platelet percentages between the two groups. Additional assays of platelet activation (PAC-1 expression, Annexin V binding, platelet microparticles and complexes) are being developed and assessed with respect to disease activity, thrombosis risk and effects of antithrombotic therapy.

Unstable coronary syndromes usually involve platelet activation and thrombus formation at the site of atherosclerotic plaque. P-selectin in platelets and endothelial cells mediates adhesive interaction with leucocytes to form thrombi. The aim of this study was to asses the level of soluble P-selectin (CD62P) as a non invasive marker of coronary plaque destabilization in unstable angina (U.A.). Serum samples were collected from 23 male patients with UA, 20 male patients with stable angina (SA) and 13 healthy controls. Soluble P-selectin (sP-selectin) level was measured by ELISA technique. The mean sP-selectin level was significantly higher in patients with UA (87.6+/-30.10 ng/ml) than SA (36.2 +/-13.8 ng/ml) and control subjects (16.7+/-8.6 ng/ml). In conclusion, s-Pslectin level could be used as a marker of plaque destabilization in unstable angina.

BACKGROUND

Acute exercise has been associated with activation of thrombosis, and this risk may be accentuated in patients with heart failure. Given the relation of platelets to atherothrombosis, we tested the hypothesis that acute exercise would adversely affect platelet indices and platelet activation markers in patients with systolic and diastolic heart failure.

METHODS

We studied 20 patients with systolic heart failure (17 men, 3 women; mean age 64 +/- 10 years, all with ejection fraction (EF) < or = 40%) and 20 patients with diastolic heart failure (14 men, 6 women; mean age 64 +/- 8 years, mean EF = 66%) who were exercised to maximal intensity, who were compared to 13 healthy controls (6 men, 7 women; mean age 60 +/- 4 years, mean EF = 73%). We measured platelet indices (platelet volume, mass and component) and platelet activation markers (platelet-bound CD62P%G, CD63%G and CD40L%G using flow cytometry, as well as plasma sCD40L and soluble P-selectin (sP-sel) levels).

RESULTS

Baseline Mean Platelet Volume (MPV), sP-sel, CD40L%G and CD63%G levels were significantly higher in patients with systolic and diastolic heart failure, when compared with controls. The mean exercise duration and VO(2 )peak in patients with systolic and diastolic heart failure were not significantly different, but lower than that seen in healthy controls. Following exercise, mean haematocrit, CD62P%G, and CD63%G significantly increased in all three subject groups (all P < 0.05). The proportional change in CD62P%G and CD63%G were not significantly different between healthy controls and heart failure patients (P>> 0.05).

CONCLUSIONS

Acute maximal graded exercise increases platelet activation markers, with no disproportionate differences between heart failure patients and healthy controls, despite the former group having a lower exercise tolerance and VO2 peak.

OBJECTIVE

To explore the expression of platelets microparticles (PMPs) in peripheral blood (PB) and synovial fluid (SF) of rheumatoid arthritis (RA) patients and its correlation with clinical inflammatory parameters.

METHODS

The levels of PMPs in PB were detected by flow cytometry in 26 active RA patients and 15 healthy control (HC). SF was collected from 16 patients. The percentages of CD62P+PMPs, CD154+PMPs and clinical parameters (including CRP, ESR, RF and ACPA) were also measured, then the correlations of PMPs with these parameters were analyzed.

RESULTS

PMPs levels in PB of RA patients were higher than those in PB from HC and those in SF of RA patients (P< 0.01). CD62P+PMPs levels in PB of RA patients were higher than those in PB of HC and those in SF of RA patients (P< 0.05). CD154+PMPs levels in PB of RA patients were higher than those in PB of HC (P< 0.01) and those in SF of RA patients (P< 0.05). The levels of PB PMPs were positively correlated with disease activity score DAS28 ( r=0.462, P=0.018), but not with ESR, CRP, RF or ACPA. The levels of SF PMPs were not correlated with any of them (P>0.05).

CONCLUSIONS

PMPs may be involved in immune regulation and systemic inflammation of RA. The elevated levels of PMPs could be a potential biomarker for RA.

Microanatomical compartments of the human spleen are yet under evaluation as most of the present information comes from experiments on animals with different anatomical structures. Immune staining of stromal and blood-born cells by cell surface antigens facilitates the differentiation of functional microanatomical compartmentalization of immune organs, including the spleen. Twenty-two specimens from healthy adult subjects with the average age of 35.6 +/- 13.8 (Range 17 to 58) years were included in this study. Monoclonal antibodies used in this study were supplied from the 5th, 6th and 7th International Workshops and Conferences on Human Leukocyte Differentiation Antigens. Tetraspan antigens presented a rather unique staining pattern in the human spleen, suggesting special roles for each (CD9, CD53, CD63, CD151 and CD231) in certain locations. Sinus lining cells presented a distinctive antigenic profile, sharing both endothelial cell (CD31, CD36, CD54, CD62P, CD102, CD105, CD106 and CD146) and macrophage lineage characteristics. The sheathed capillaries were not restricted to the perifollicular zone alone. Extracellular matrix receptors (CD49 a, CD49 b, CD49 c, CD49 e, CD49f, CD29 and CD44) stained the penicillary arterioles and vascular smooth muscle. These molecules were also found on the vascular endothelium. Leukocyte antigens (CD11a, CD11b, CD22, CD43, CD45, CD45RB, CD45RO and CD50) were mainly expressed in the white and red pulp of the spleen at different intensities, excluding the penicillary arterioles. Activation antigens (CD26, CD71 and CD98) presented a diffuse and broad staining pattern. In conclusion, microanatomical compartmentalization, microcirculation and function of the human spleen were evaluated using a wide panel of monoclonal antibodies.

BACKGROUND

The interaction of blood with foreign artificial surfaces during cardiopulmonary bypass (CPB) has been recognized as a major stimulus in evoking a systemic inflammatory and metabolic response. Phosphorylcholine (PC) is a new-generation coating material designed to ameliorate biocompatibility and thereby to reduce the detrimental interactions of CPB. We studied the effects of PC-coated perfusion circuits on platelet function and the humoral and cellular response to CPB.

METHODS

Thirty patients undergoing coronary artery bypass grafting were randomized to PC-coated (PC group, n = 15) and noncoated (control group, n = 15) circuit groups. Clinical data, total blood loss, and pre- and postoperative platelet counts were recorded and IL-6 and TNF-alpha, CD41a, CD42b, and CD62p were measured at induction of anesthesia, after the initiation of CPB and at termination of CPB.

RESULTS

There was a significantly improved preservation of platelet count following CPB in the PC group (p = 0.028), which was sustained over a period of 72 hours. The use of PC-coated circuits further resulted in a significant attenuation of TNF-alpha and IL-6 expression (p < 0.05 and p < 0.01); however, we were unable to detect any differences in clinical outcomes.

CONCLUSIONS

Despite similar clinical outcome, the obvious reduction of cytokine expression and improved preservation of platelet count suggest superior biocompatibility of PC-coated circuits.

Vascular thrombosis is a harbinger of failure in microsurgery. However, there is still controversy regarding the correlation of the complications of thrombocytosis and thrombosis. Some evidence indicates that patients with elevated platelet counts tend to have a higher flap failure rate, and surgeons usually hesitate to operate on patients with thrombocytosis. Nevertheless, the authors have experienced successful free tissue transfer in seven patients with thrombocytosis resulting from traumatic splenectomy or multiple trauma. On the basis of clinical observation, the authors investigated whether reactive thrombocytosis contributes to the patency of a microvascular anastomosis. In a rodent splenectomy-induced thrombocytosis model (n = 40), stable reactive thrombocytosis occurred after postoperative days 5 to 10, with the peak on postoperative day 7. Femoral artery division and reanastomosis was performed in rats with or without splenectomy-induced thrombocytosis, and vascular patency was assessed. Platelet counts and platelet activation were studied in correlation to microvascular patency. Platelet activation as demonstrated by CD62P expression on platelets was not significantly different between rats with and without thrombocytosis (6.41 +/- 0.95 percent versus 4.51 +/- 0.55 percent, respectively; p = 0.089). As immature platelets were not increased (2.86 +/- 0.33 percent versus 1.99 +/- 0.32 percent, p = 0.074), it seems that the splenectomy-induced thrombocytosis is the result of redistribution of platelets instead of an increase in bone marrow production. There were no significant differences in the patency rates or perfusion units of femoral artery after arterial anastomosis between rats with and without thrombocytosis (90 percent and 95 percent, respectively; p = 0.561). In conclusion, this study demonstrates that microvascular anastomosis can be performed safely in patients with reactive thrombocytosis without platelet activation.

BACKGROUND

Although platelet activation has been considered an important reaction after percutaneous transluminal coronary angioplasty (PTCA), it is still difficult to detect the activated platelets in vivo directly.

METHODS

To detect platelets activated at an early stage after PTCA, blood samples were take from the coronary sinus and the aorta in 22 patients with coronary artery disease, who underwent PTCA for a lesion of the left anterior descending artery. Ten patients with coronary artery disease, who underwent diagnostic coronary angiography only, were compared with them. The expression of activation-dependent granular protein, CD62P (P-selectin) and CD63, on the platelet membrane surface was analysed using flow cytometry. The plasma thrombomodulin level was also measured.

RESULTS

The percentage of platelets positive for CD62P (0.53 +/- 0.04 to 0.80 +/- 0.11%, P < 0.01) and CD63 (16.0 +/- 1.4 to 19.8 +/- 2.0%, P < 0.05) increased after PTCA in the coronary sinus, although it did not change in the aorta. The plasma thrombomodulin level also increased after PTCA in the coronary sinus (16.7 +/- 1.0 to 20.4 +/- 2.0 mu/ml, P < 0.05). However, these parameters did not change after coronary angiography only. After PTCA, the plasma thrombomodulin level was correlated with the percentage of platelets positive for CD62P (r = 0.88, P < 0.001) and with that for CD63 (r = 0.69, P < 0.001) in the coronary sinus.

CONCLUSIONS

PTCA produced activation of circulatory platelets, which might have been caused by balloon-induced vascular endothelial injury. One should take care to avoid needless vascular injury during the PTCA procedure to inhibit the platelet activation.

Recurrent airway obstruction (RAO) in mature horses is characterized by reversible airway obstruction and neutrophilic inflammation; there is also functional activation of circulating platelets and neutrophils. This study was undertaken to determine if changes in activation marker expression and heterotypic aggregate formation can be used as an indicator of this increased functional responsiveness. In vitro conditions for flow cytometric measurement of CD13, CD41/61 and CD62P expression on activated cells and heterotypic aggregate formation were established. Values were then compared before and after antigen challenge of RAO and healthy horses. Platelet adhesion to serum-coated plastic was measured as a functional marker of platelet activation. In vitro activation resulted in increased expression of neutrophil CD13 and platelet CD41/61 and CD62P. Activation of both cell types caused a significant increase in neutrophil-platelet aggregates. In horses with RAO, but not controls, there was a significant increase in the percentage of CD13 positive neutrophils at 10h and 24h and in the mean fluorescence intensity at 10h. This was accompanied at 24h by an increased mean platelet side scatter and thrombin-stimulated platelet adhesion. In conclusion, CD13 expression can be used as an indicator of equine neutrophil activation both in vitro and in vivo. Equine platelet activation in vitro can be detected by measuring CD41/61 or CD62P expression, and PAF-activated platelets and neutrophils form aggregates. However, despite evidence of circulating platelet activation, neither a change in expression of platelet activation markers, nor heterotypic aggregate aggregate formation could be detected.

OBJECTIVE

At Canadian Blood Services, buffy coat (BC) platelet concentrates (BC-PCs) show a generally lower bacterial contamination rate than apheresis PCs. This study investigated whether the PC production method contributes to this observation.

METHODS

Whole blood (WB) inoculated with eight bacterial strains was processed using the BC method. Bacteria were enumerated throughout BC-PC production and subsequent PC storage. Endotoxin production and bacterial adhesion to PC bags were evaluated during PC storage. PC quality was monitored by CD62P expression (flow cytometry) and changes in dynamic light scattering (ThromboLUX® ).

RESULTS

During overnight WB hold, Staphylococcus epidermidis titres remained unchanged, commercial Escherichia coli and Klebsiella pneumoniae were eliminated and the remaining organisms proliferated to high concentrations. Through BC-PC production, bacteria segregated preferentially towards the cellular fractions compared to plasma (P < 0·05). During PC storage, most bacteria adhered to the PC bags and Gram negatives produced clinically significant endotoxin levels. Changes in CD62P expression or ThromboLUX scoring did not consistently reflect bacterial contamination in BC-PCs.

CONCLUSIONS

WB hold during BC-PC production does not have a broad-spectrum bactericidal effect, and therefore, other factors contribute to low rates of contamination in BC-PCs.

UNASSIGNED

Cord blood transplantation (CBT) can be a life-saving procedure in the treatment of a broad variety of disorders, including hematologic, immune, and genetic diseases. However, delayed platelet recovery hinders the application of CBT.

UNASSIGNED

The aim of this study was to determine the optimal combination of cytokines to amplify megakaryocyte (Mk).

UNASSIGNED

CB CD34+ cells were obtained by immunomagnetic isolation and amplified under four different cytokine combinations. CD34+ cells of the group with thrombopoietin (TPO), stem cell factor (SCF), Flt-3 ligand (FL), and interleukin-6 (IL-6) were collected on days 0, 3, 7, 10, and 14. Immunophenotype was analyzed by flow cytometry (FCM). Polyploidic Mk cultured cells were collected on days 7 and 14 for colony-forming unit-Mk assay. The NOD/SCID mice were injected with expanded CD34+ cells, and the peripheral blood (PB) and bone marrow (BM) were tested on 3, 7, and 14 days.

UNASSIGNED

The group with TPO, SCF, FL, and IL-6 reached the maximal total expansion fold and Mk population at day 7, which was slightly reduced later. After transplantation into NOD/SCID mice with expanded CD34+ cells, the human CD41+ cells were detected in mice PB on day 3 and in BM on day 7, then disappeared after 14 days. The expressing of activated platelet CD 42b+/CD62P+ increased gradually after transplantation.

UNASSIGNED

Platelets can recover rapidly in vivo by means of expanded CD34+ cells with various cytokines. In our system, a group of TPO, SCF, FL, and IL-6 represents the best cytokine combination for expansion of Mk progenitor cells from CB CD34+ cells.

In rheumatoid arthritis (RA), a key event is infiltration of inflammatory immune cells into the synovial lining, possibly aggravated by dysregulation of cellular adhesion molecules. Therefore, single nucleotide polymorphisms of 14 genes involved in cellular adhesion processes (CAST, ITGA4, ITGB1, ITGB2, PECAM1, PTEN, PTPN11, PTPRC, PXN, SELE, SELP, SRC, TYK2, and VCAM1) were analyzed for association with RA. Association analysis was performed consecutively in three European RA family sample groups (Nfamilies = 407). Additionally, we investigated differential allelic expression, a possible functional consequence of genetic variants. SELP (selectin P, CD62P) SNP-allele rs6136-T was associated with risk for RA in two RA family sample groups as well as in global analysis of all three groups (ptotal = 0.003). This allele was also expressed preferentially (p<10-6) with a two- fold average increase in regulated samples. Differential expression is supported by data from Genevar MuTHER (p1 = 0.004; p2 = 0.0177). Evidence for influence of rs6136 on transcription factor binding was also found in silico and in public datasets reporting in vitro data. In summary, we found SELP rs6136-T to be associated with RA and with increased expression of SELP mRNA. SELP is located on the surface of endothelial cells and crucial for recruitment, adhesion, and migration of inflammatory cells into the joint. Genetically determined increased SELP expression levels might thus be a novel additional risk factor for RA.

OBJECTIVE

To study the correlation between prethrombotic biomarkers and traditional Uyghur medicinal syndromes of malignant tumor.

METHODS

One hundred and fifty-nine malignant tumor inpatients were randomly selected and typed according to traditional Uyghur medicine theories. The expressions of peripheral platelet membrane glucoprotein (CD41 and CD62p), levels of serum endothelin (ET-1), plasma tissue plasminogen activator (t-PA), plasminogen activator inhibitor (PAI), plasma fibrinogen (FIB), prothrombin time (PT), and thrombin time (TT), and activated partial thromboplastin time (APTT) were detected by flow cytometry, radioimmunoassay, and enzyme-linked immunosorbent assay (ELISA) respectively.

RESULTS

The patients were typed as 68 of abnormal Savda syndrome, 34 of abnormal Khan syndrome, 31 of the abnormal Sepra syndrome, and 26 of the abnormal Belghem syndrome. Compared with the control group, the levels of CD62p, PAI, and ET-1 increased, levels of FIB and t-PA decreased, PT prolongated and APTT shortened in the abnormal Savda group and the non-abnormal Savda group (including abnormal Khan, abnormal Sepra, and abnormal Belghem types) (all P < 0.05). No significant difference of CD41 or TT was shown in inter-group comparison (P>> 0.05). Compared with abnormal Khan and Belghem groups, the ET-1 level increased in the abnormal Savda group (P < 0.05). Compared with the abnormal Sepra group, the CD62p positive percentage increased in abnormal Savda group (P < 0.05). No significant difference in CD41 positive percentage, t-PA or PAI-1 contents, PT, TT, or APTT was shown in patients of different traditional Uyghur medicine syndrome groups (P>> 0.05).

CONCLUSIONS

Prethrombotic changes existed in malignant tumor patients of different Uyghur abnormal syndrome types, manifested as injuries of vessel epithelial cells, platelet activation, increased blood viscosity, lowered fibrinolytic function. The prethrombotic changes were more obviously seen in the abnormal Savda group.

Platelets are known to undergo shape change, activation, a release reaction and apoptosis/necrosis during processing and storage, all of which are collectively known as the platelet storage lesion. Any additional processing may have some deleterious impact on platelet activability and functional integrity, which need to be investigated. This preliminary investigation was undertaken to establish the combined effects of standard platelet storage media and the intercept pathogen reduction technology on platelet activation and activability during 7 day storage, using buffy-coat derived platelets in standard storage media containing 35% plasma (N=24). P-selectin (CD62p) expression, a classical marker of platelet activation, and phosphatidylserine (PS) exposure on the platelet surface membrane, a hallmark of cellular necrosis/apoptosis, were both measured by flow cytometry. The results reveal significant increases in activation, from an average of 22.7% on day 1 before treatment to 31.6% on day 2 after treatment and 58.7% at the end of storage. Concomitantly, the basal expression of PS was slightly increased from 1.9% to 2.8% at day 2 after treatment and 7.3% at the end of storage. However, the functional reserve of platelets during storage, which reflects their capability to undergo activation and the release reaction when platelets were challenged with either calcium ionophore or thrombin, was relatively well maintained. These preliminary data confirm the earlier data on the use of intercept, and for the first time, based on the assessment of platelet functional integrity, suggest that platelet functional reserve is relatively well maintained, with little change in the formation of apoptotic cells.

OBJECTIVE

To study the correlationship between TCM Syndrome type with changes of neutrophil surface intercellular adhesion molecule-1 (ICAM-1) and platelet membrane P selectin (CD62P) in patients with ischemic stroke for exploring the pathogenesis of the disease.

METHODS

Seventy-two patients with ischemic stroke were dividcd into 3 typing groups according to TCM syndrome-differentiation, the Meridian-phlegm stagnancy group (MPS), the visceral phlegm-heat accumulation group (VPHA) and the qi-deficiency with blood stasis group (QDBS), 24 in each group. Besides, a control group consisted of 24 healthy subjects was set up. Blood levels of ICAM-1 and CDP62 expression were monitored by flow cytometry.

RESULTS

Blood levels of ICAM-1 and CD62P expression in ischemic stroke patients were significantly higher than those in healthy subjects (P < 0.01). Among the three type groups, ICAM-1 expression was significantly higher in MPS than that in the VPHA and the QDBS group (P<0.01), and CD62P expression in the MPS and the QDBS group was significantly higher than that in the VPHA (P <0.01).

CONCLUSIONS

Blood levels of ICAM-1 and CD62P expression in different typing of patients with ischemic stroke are different. ICAM-1 expression reflects the pathological state of phlegm retention or phlegm-stasis mutual bindings, CD62P expression reflected the blood stasis state in organism, these evidences suggest that MPS may be the key pathogenic factor of ischemic stroke.

Leptin is an adipokine that in vitro enhances agonist-induced platelet aggregation and adipokine expression. Hyperleptinaemia represents a risk factor for cardiovascular disease. We conducted a prospective evaluation of the potential link between blood platelet activation and plasma leptin levels in post-stroke patients. Using five-colour flow cytometry, the platelet surface expression of CD40L, CD62P, the subpopulations of monocyte-platelet aggregates and platelet-derived microparticles (PMPs) as well as the plasma leptin, soluble leptin receptor (sOb-R), leptin/sOb-R ratio, the plasma adiponectin, and leptin/adiponectin ratio were assessed in 98 stroke patients on the first (V₀), 10th (V₁ ) and 90th (V₂) day after stroke and once in 78 age-, gender- and vascular risk factor-matched disease controls. We demonstrated that at V0 leptin resistance, defined as leptin/sOb-R ratio, was higher than in the controls [1.1 (0.5-1.8 vs. 0.5 (0.2-1.1); p=0.02]. After adjustment according to the factors which influence platelet activation, we confirmed the relationship between percentage of circulating PMPs and plasma leptin level (B=0.18; p=0.02) or the leptin/sOb-R ratio (B=0.23; p=0.02) in normal-weight subjects in the acute phase of stroke. No correlation could be demonstrated between the adipokine parameters and the percentage of monocyte-platelet aggregates or expression of platelet pro-inflammatory glycoproteins. In conclusion, formation of PMPs on the first day following an ischaemic stroke shows a positive correlation with leptin levels and with resistance to leptin. Leptin level does not seem to affect the expression of platelet surface proinflammatory glycoproteins.

Background. The use of plasma frozen within 24 hrs is likely to increase. Whole blood (WB) and buffy coats (BCs) can be held for a few hrs or overnight before processing. Methods. Twenty-four bags of WB for plasma and 12 bags for platelet (PLT) concentrates were collected. The fresh frozen plasma (FFP) was prepared within 6 hrs. I-FP24 and II-FP24 samples were prepared either from leukodepleted WB that was held overnight or from WB that was held overnight before leukodepletion. The PLT concentrates (PCs) were prepared from BCs within 6 hrs (PC1) and within 18 to 24 hrs (PC2). The typical coagulation factors and some biochemical parameters were determined. Results. Compared to the FFP samples, the levels of FVII and FVIII in the I-FP24 and II-FP24 samples decreased significantly. The pH, Na(+), LDH, and FHb levels differed significantly between II-FP24 and FFP. Compared to PC1, PC2 exhibited lower pH, pO2, and Na(+) levels, a higher PLT count, and increased pCO2, K(+), Lac, and CD62P expression levels. Conclusion. FP24 is best prepared from WB that was stored overnight at 4°C and then leukodepleted and separated within 24 hrs. PCs are best produced from BCs derived from WB that was held overnight at room temperature.

Diabetes mellitus alters blood coagulation and platelet function which supports the suggestion that diabetes mellitus is a hypercoagulable state. Firstly the aim of the study was to investigate if differences in platelet activity, reactivity and platelet-leukocyte conjugate (PLC) formation can be observed in subjects with IDDM; secondly, if differences can be seen between the diabetic and control group concerning exercise-induced changes in platelet activation and conjugate formation; and thirdly, if different types of exercise lead to different patterns in platelet activation. Sixteen subjects with IDDM and 16 controls underwent a maximal step test and an endurance test (90% IAT, 45 min). Blood samples were taken after 30 min rest, and immediately and 1 h after completion of exercise. CD62P expression and differentiated platelet-leukocyte conjugates (CD45, CD14, CD41) were detected flow-cytometrically with and without stimulation with TRAP-6. The rest values of the platelet-granulocyte (PGC) and platelet-lymphocyte conjugates (PLyC) were higher (P < 0.05) in the diabetics. After exercise, platelet reactivity (CD62P-TRAP; P < 0.05) but not the activity (CD62P-unstimulated), as well as all different conjugates with or without stimulation were increased (P < 0.05) independently from the group. Differences according to the type of exercise were barely observable. IDDM without vascular complications leads to higher PCG and PLyC at rest and to identical increases in differentiated platelet-leukocyte formation after exercise in comparison with matched controls.

Hematopoietic recovery after transplantation with cord blood (CB) is slower than with bone marrow (BM) and mobilized peripheral blood. Adhesion molecules (AMs) on hematopoietic cells are involved in hematopoietic cells' homing. It may be possible to enhance CB CD34+ cells engraftment by increasing their expressions of AM. Twenty-three patients with childhood acute leukemia treated with unrelated CBT were studied. It was found that the time to neutrophil recovery correlated with CXCR4 and the time to platelet recovery correlated with both CD62L and CXCR4. Platelet microparticles (PMPs) carry some AMs such as aIIb b (CD41), P-selectin (CD62P), and CXCR4, CD34+ cells express platelet-binding antigens (CD162 and CD11b). It was found that AMs were increased dramatically on CD34+ cells surface in the presence of PMPs, and CD34+ cells covered with PMPs adhered better to human umbilical vein endothelial cells and fibronectin. These findings suggested that PMPs could increase adhesion of donor's cells to host BM in CBT.

Summary Previous findings of megakaryocytic hypogranulation and dysmegakaryocytopoietic features in acute myeloid leukaemia (AML) strongly indicate defects in platelet production. The bleeding tendency of these patients may result from dysregulated platelet production, resulting in thrombocytopenia as well as qualitative platelet defects. The present study examined platelet function at diagnosis in 50 AML patients by whole blood flow cytometry. Following in vitro platelet agonist stimulation, platelet activation markers were analysed and compared with 20 healthy individuals. To detect recent in vivo platelet activation, plasma soluble P-selectin (sP-selectin) was measured. Flow cytometric analysis of platelet activation markers demonstrated reduced CD62P [35.6 vs. 118.5 x 10(3) molecules of equivalent soluble fluorochrome (MESF); P < 0.0001], CD63 (11.3 vs. 50.7 x 10(3) MESF; P < 0.0001), and PAC-1 (41.5 vs. 90.5%; P = 0.0001) while reductions in CD42b were abnormal (45.6 vs. 70%; P < 0.0001). sP-selectin levels were similar in patients and healthy controls (0.04 vs. 0.27 fg/platelet; P = 0.84). The presented data indicate that AML pathogenesis may result in multiple platelet defects, involving adhesion, aggregation, and secretion and demonstrate that flow cytometry is a feasible method for platelet function analysis in patients with thrombocytopenia.