BACKGROUND

It remains unestablished whether use of cyclooxygenase (COX)-2 inhibitors impairs platelet activation and anabolic growth factor release from platelets in platelet-rich plasma (PRP).

OBJECTIVE

The purpose of this study was to assess the effects of a COX-2 inhibitor on platelet activation and anabolic growth factor release from canine PRP when using a clinically applicable PRP activator and to determine whether a 3-day washout would be sufficient to abrogate any COX-2 inhibitor-related impairment on platelet function.

METHODS

Controlled laboratory study.

METHODS

Ten healthy dogs underwent blood collection and PRP preparation. Dogs were then administered a COX-2 inhibitor for 7 days, after which PRP preparation was repeated. The COX-2 inhibitor was continued for 4 more days and PRP preparation performed a third time, 3 days after discontinuation of the COX-2 inhibitor. Immediately after PRP preparation, the PRP was divided into 4 aliquots: 2 unactivated and 2 activated using human γ-thrombin (HGT). One activated and 1 unactivated sample were assessed using flow cytometry for platelet expression of CD62P and platelet-bound fibrinogen using the canine activated platelet-1 (CAP1) antibody. The 2 remaining samples were centrifuged and the supernatant assayed for transforming growth factor-β1 (TGF-β1), platelet-derived growth factor-BB (PDGF-BB), and thromboxane B2 (TXB2) concentrations. Differences in platelet activation and TGF-β1, PDGF-BB, and TXB2 concentrations over the 3 study weeks were evaluated using a 1-way repeated-measures ANOVA, and comparisons between activated and unactivated samples within a study week were assessed with paired t tests.

RESULTS

There were no statistically significant ( P>> .05) effects of the COX-2 inhibitor on percentage of platelets positive for CD62P or CAP1 or on concentrations of TGF-β1, PDGF-BB, or TXB2. All unactivated samples had low levels of activation or growth factor concentrations and significantly ( P < .05) greater activation and growth factor concentrations in HGT-activated samples.

CONCLUSIONS

This COX-2 inhibitor did not impair platelet activation, growth factor release, or TXB2 production in this canine PRP when using HGT as an activator. Studies are warranted to determine whether COX-2 inhibitors affect platelet activation and growth factor release from human PRPs.

CONCLUSIONS

These results suggest that there is no need to withhold a COX-2 inhibitor before PRP preparation, particularly if thrombin is going to be used to activate the PRP. This is clinically relevant information because many patients who are candidates for PRP therapy for treatment of musculoskeletal injury are also using COX-2 inhibitors.

Platelets orchestrate the inflammatory activities of neutrophils, possibly contributing to pulmonary and myocardial damage during severe pneumococcal infection. This study tested the hypothesis that the pneumococcal toxin, pneumolysin (Ply), activates production of platelet-activating factor (PAF) and thromboxane A2 (TxA2) by neutrophils, these bioactive lipids being potential mediators of neutrophil:platelet (NP) networking.

The effects of recombinant Ply (10-80 ng mL-1) on the production of PAF and TxA2 by isolated neutrophils were measured using ELISA procedures, and NP aggregation by flow cytometry.

Exposure of neutrophils to Ply induced production of PAF and, to a lesser extent, TxA2, achieving statistical significance at ≥20 ng mL-1 of the toxin. In the case of NP interactions, Ply promoted heterotypic aggregation which was dependent on upregulation of P-selectin (CD62P) and activation of protease-activated receptor 1 (PAR1), attaining statistical significance at ≥10 ng mL-1 of the toxin, but did not involve either PAF or TxA2.

Ply induces synthesis of PAF and TxA2, by human neutrophils, neither of which appears to contribute to the formation of NP heterotypic aggregates in vitro, a process which is seemingly dependent on CD62P and PAR1. These pro-inflammatory activities of Ply may contribute to the pathogenesis of pulmonary and myocardial injury during severe pneumococcal infection.

Platelet function of immune thrombocytopenia (ITP) has been controversial because of methodological problems associated with low platelet counts. In this study, we evaluated platelet function in 21 patients with chronic ITP (cITP) using the recently developed flow cytometry (FCM)-based platelet aggregation assay (FCA) along with a PAC1/CD62P assay. Since ITP platelets are larger than controls, whole platelets (whole gating method) and size-adjusted platelets (size-adjusted method) were analysed in the PAC1/CD62P via FCM. We found that: (i) aggregation was equivalent [phorbol myristate acetate (PMA) or adenosine diphosphate (ADP)-induced] or enhanced [protease-activated receptor 1-activating peptide (PAR1AP)-induced] in cITP compared with control by FCA; (ii) PAC1 or CD62P was also equivalent or enhanced in cITP in the whole gating method; and (iii) in sharp contrast, the size-adjusted method revealed that ADP-, PAR1AP-, and collagen synthetic liquid reactive peptide (SRP)-induced PAC1 and ADP-induced CD62P were impaired in cITP. These data suggested that an increase in the number of larger-sized platelets may compensate for the impaired platelet function of cITP, leading to non-inferiority of overall platelet function in cITP. Furthermore, we revealed that ADP-induced aggregation was impaired in the patients with thrombopoietin receptor agonists (TPO-RAs) or platelet-associated anti-αIIbβ3 antibodies compared with the control, suggesting that the presence of anti-αIIbβ3 autoantibodies and/or administration of TPO-RAs may have a negative impact on platelet function.

BACKGROUND

White cell reduction of blood products minimizes the risks of alloimmunization against HLA-antigens, the transmission of viral diseases and the incidence of platelet transfusion reactions. One modern strategy is leukocyte depletion with an integrated filter system immediately after preparation and prior to storage.

METHODS

We evaluated the efficiency of a novel in-line filter system Sepacell PLX-5 BPS for leukocyte reduction of platelet concentrates (PC) from pooled buffy-coats. A total of 44 PCs were investigated with regard to different filtration flow rates (25-110 ml/min) and leukocyte depletion and thrombocyte recovery rates were analysed. Furthermore, we studied the influence of filtration on PCs over a storage period of 6 days (n = 12) by investigation of pH, lactate and glucose. Platelet function was determined by means of hypotonic shock response, external shape change and expression of CD62p.

RESULTS

The mean leukocyte depletion rate was>> log 5. After filtration the mean leukocyte count was 0.12 +/- 0.21 x 10(6). In 60% of the PCs the leukocyte count lay below the detection level of the Nageotte chamber, which is < 0.3 x 10(5). The flow rate correlates significantly with the leukocyte count in the PCs (r = 0.325; p = 0.033) and therefore with the leukocyte depletion rate (r = -0.422; p = 0.01). Flow rates under 40 ml lead to a significantly lower leukocyte contamination. Only in one PC, at a flow rate of 84 ml/min, was the leukocyte threshold of 1 x 10(6) exceeded. We did not find a significant correlation between filtration flow rate and thrombocyte recovery (r = 0.315; p = 0.069). The mean platelet count in the PC was 2.88 +/- 0.47 x 10(11). Compared with the thrombocyte count in the pooled buffy coat, the recovery was 68.6%. We observed a decrease of pH, glucose, external shape change and hypotonic shock response over the storage period while lactate and the expression of CD62p increased.

CONCLUSIONS

The filter system Sepacell PLX-5 BPS proved to be suitable for in-line filtration of platelet concentrates prior to storage. Filtration flow rates of up to 40 ml/min allowed efficient leukocyte depletion without significant loss in the quality of the platelet concentrates and the platelet function in vitro.

Use of recently developed platelet (PLT) additive solutions (PAS) with 5% plasma levels may reduce the frequency and/or severity of transfusion reactions attributed to plasma. PLTs suspended in bicarbonate-containing PAS-5 with 5% plasma levels can maintain key PLT parameters during 7-day storage. This study evaluates the role of calcium and phosphate, as constituents of PAS-5, in maintaining PLT parameters.

An Amicus apheresis PLT unit (n = 13) was equally divided into four 60-mL aliquots in CF-250 polyolefin bags. Four different formulations of PAS-5 were prepared: PAS-5, PAS-5 without phosphate (-PO4 ), PAS-5 without calcium (-Ca), and PAS-5 without Ca and phosphate (-Ca/-PO4 ). PLTs were centrifuged, and the supernatant was expressed and replaced with the respective PAS, yielding PLTs suspended in 95% PAS and 5% plasma. PLTs were stored at 20 to 24ºC with agitation for 7 days. PLT in vitro parameters were evaluated on Days 1, 5, and 7.

In PLT PAS-5 aliquots, pH levels were maintained better compared with those in -Ca and -Ca/-PO4 aliquots. Glycolysis was greater in -Ca and -Ca/-PO4 PLT aliquots compared with PAS-5 aliquots. Hypotonic stress response and morphology were less and p-selectin (CD62P) binding was greater in -Ca/-PO4 PLT aliquots. The accumulation of reactive oxygen species was greater in -Ca/-PO4 PLTs. Phosphorylation of p38 mitogen-activated protein kinase (MAPK) was greater in -Ca and -Ca/-PO4 PLT aliquots during storage.

The removal of calcium and phosphate from PAS-5 leads to the activation of p38 MAPK and deterioration of key PLT storage parameters.

OBJECTIVE

To study the relationship between blood stasis and platelet activation and the influential factors on the latter in type 2 diabetes mellitus (DM) patients.

METHODS

Platelet CD62p, CD63 expressions were determined in 30 patients of type 2 DM with blood stasis, 27 patients of type 2 DM without blood stasis and 20 normal controls by flow cytometry.

RESULTS

CD62p, CD63 levels were significantly higher in type 2 DM with blood stasis group than that without blood stasis group and in normal controls. CD62p was positively correlated with CD63, while positive correlation existed between HbA1c, LDL-C and CD62p in DM patients with blood stasis.

CONCLUSIONS

The increased level of platelet activation was the primary molecular basis in type 2 DM. It was important to perform the Syndrome Differentiation of blood stasis and treatment of activating blood circulation to remove blood stasis in type 2 DM.

OBJECTIVE

To investigate microcosmic essentials of blood stasis syndrome (BSS) at the gene level.

METHODS

One hundred and sixty patients with hypertension or diabetes mellitus, BSS or non-BSS, were strictly selected in disease-syndrome integrated mode according to diagnosis standard. The expression of CD62p gene and HSP70 gene in them were observed, compared and analyzed with blood biochemical indexes by experimental techniques, and compared to those in healthy subjects as control, for exploring the microcosmic mechanism and evolutive rules of BSS formation at the gene level.

RESULTS

It was showed, through determination and analysis of the microcosmic indexes closely associated with BSS, that the expression of CD62p gene and HSP70 gene were abnormal in patients with BSS, they were increased in patients with BBS and significantly higher than those in healthy subjects (P < 0.01). The abnormality and level of them were closely correlated with the types of BSS.

CONCLUSIONS

CD62p gene and HSP70 gene might be closely associated with BSS.

This study was aimed to evaluate the efficiency and effectiveness of platelet-rich plasma(PRP) prepared by acute plateletpheresis in patients undergoing open heart surgery, and to analyze the quality of prepared platelet-rich plasma. Whole blood from 20 patients with ASAII-III was collected and PRP was harvested by machine after induction of anesthesia. Platelet count (Plt), mean platelet volume (MPV), platelet distribution width (PDW), plasma pH, plasma lactic acid (LA) concentration, and lactic dehydrogenase (LDH) concentration, germiculture result, CD62p and PAC-1 positive rate of inactivated and activated platelets by ADP in the whole blood before plateletpheresis (T1) , in the PRP after plateletpheresis (T2) and PRP before back-transfusion (T3) were determinated. The results showed that as compared with whole blood the platelet count in the PRP at T2 was (783 ± 184) ×10(9)/L, MPV, PDW and pH significantly decreased (P < 0.01) , while the plasma LDH, LA concentration, CD62p and PAC-1 positive rate of inactivated platelets were not significantly different from the whole blood at T1. In the PRP at T3, the platelet count, MPV, PDW and pH significantly decreased (P < 0.01) , while plasma LDH concentration, CD62p and PAC-1 positive rate of inactivated platelet significantly increased (P < 0.05 or P < 0.01) compared with the whole blood at T1. There were no significant difference among the CD62p and PAC-1 positive rate of activated platelets in the whole blood and PRP. It is concluded that PRP can be efficiently obtained from the patients undergoing open heart surgery by acute plateletpheresis, and the platelets in PRP are not activated during the preparing process. Some platelets in PRP are activated during the preserving process, but the whole activating function of platelets keeps normal.

To evaluate the efficiency and effectiveness of batch preparing cryopreserved fresh platelet-rich plasma (cryo-FPRP) derived from the volunteer donors, platelet count (Plt), mean platelet volume (MPV), platelet distribution width (PDW), plasma pH, plasma lactic acid concentration, and lactic dehydrogenase (LDH) concentration, germiculture, CD62p positive rate, PAC-1 positive rate, and the fluorescence intensity of platelet GPIb-IX-V were detected in ACD whole blood, fresh platelet-rich plasma (FPRP), FPRP with 5% dimethyl sulphoxide DMSO (DMSO-FPRP), and thawed cryopreserved FPRP (cryo-FPRP); the procoagulant activity of FPRP and cryo-FPR was determinated. The results showed that (1) 70 percentage of platelet were separated from the whole blood into FPRP, and the counts of residual erythrocyte and leucocyte were below 1 x 10(9), and below 1 x 10(7) per unit respectively. (2) The plasma pH, lactic acid concentration and PAC-1 positive rate retained a stable level during the preparing, storing and thawing process. (3) Plasma LDH concentration, platelet CD62p positive rate and GPIb-IX-V concentration in platelet surface were enhanced significantly after being frozen and thawing. (4) The plasma clotting time induced by cryo-FPRP were significantly shorter than that induced by FPRP. It is concluded that: (1) The batch platelet preparing process can efficiently obtain platelet from whole blood donated by volunteer, and the process didn't activate the platelet. (2) Cryopreservation can prevent lactic acid accumulation, pH reduce and activation of GPIIb/IIIa. (3) The membrane of partial platelets are affected by freezing and thawing. (4) The density of GPIb-IX-V complexes in platelet surface and its procoagulant activity are enhanced significantly after the FPRP freezing and thawing process.

OBJECTIVE

To determine whether expression of equine platelet activation-dependent surface markers is influenced by phospodiesterase (PDE) isoenzyme activity and whether antigen challenge alters platelet PDE activity in horses with recurrent airway obstruction (RAO).

METHODS

16 horses.

METHODS

7 healthy horses were used for in vitro experiments, 6 horses with RAO were used for antigen challenge, and 6 healthy horses were used as control animals. Three of the healthy horses had also been used in the in vitro experiments. Effects of PDE inhibition and activation of adenylyl cyclase on CD41/61 and CD62P expression on platelets and platelet-neutrophil aggregate formation in vitro were investigated via flow cytometry. Platelet PDE activity and sensitivity to inhibition of PDE3 and PDE5 isoenzymes were examined in horses with RAO and control horses before and after antigen challenge.

RESULTS

Inhibition of PDE or activation of adenylyl cyclase significantly inhibited stimulus-induced expression of CD41/61 and CD62P (by approx 94% and 40%, respectively) and percentage of CD62P positive cells (by approx 30%). Only the PDE3 inhibitor, trequinsin, caused a significant (53%) reduction in platelet-neutrophil aggregate formation. Platelet PDE activity decreased following antigen challenge in RAO-affected horses and control horses. In horses with RAO, a significant increase in sensitivity of platelet PDE to inhibition by the PDE5 inhibitor zaprinast was observed after 5 hours.

CONCLUSIONS

Results provided further evidence that PDE3 is an important regulator of equine platelet activation and suggested that changes in regulation of platelet PDE5 may contribute to antigen-induced response in horses with RAO.

BACKGROUND

Thrombogenicitiy of drug-eluting stents is a matter of controversial debate. The aim of this study was to evaluate the thrombogenicity of sirolimus-eluting stents (SES) compared to bare metal stents (BMS) in a standardised in vitro model.

METHODS

Nine SES and nine BMS were implanted in tubing loops and nine loops without stent served as controls. Initially and after 90 minutes of blood circulation in a modified chandler loop model, thrombin-antithrombin III complex (TAT), PMN-elastase, factor XIIa, SC5b-9, sP-selectin and platelet count were measured. Expression of CD62P, CD45/41 and PAC-1 on platelets were determined by flow cytometry.

RESULTS

After 90 minutes, platelet count decreased significantly in the loops with BMS and SES (p<0.05). Levels of TAT, PMN-elastase and SC5b-9 were significantly elevated after 90 minutes in all loops (p<0.05). sP-selectin significantly increased in the loops with BMS and SES after 90 minutes. No significant changes occurred in any flow cytometric data. Platelet count, sP-selectin, TAT, PMN-elastase, SC5b-9, CD62P, CD41/CD45 and PAC-1 showed no significant difference between BMS and SES.

CONCLUSIONS

These data provide evidence that there is no difference in thrombogenicity of BMS and SES in the in vitro model.

Pneumatic tube system (PTS) is an integral part of large medical facilities providing rapid interconnection between units within the hospital and often used to transport blood samples. The aim of our study was to compare a wide variety of hemostasis assays to identify assays sensitive to this transport method and diagnostic relevance of the alterations.

Routine coagulation and platelet tests (APTT, PT, TT, fibrinogen, light transmission aggregometry (LTA) with ADP, collagen, ristomycin and epinephrine), whole blood flow cytometry platelet function test (levels of CD42b, CD61, CD62P, PAC1, annexin V binding and mepacrine release) and global coagulation tests (thromboelastography (TEG), thrombin generation (TGT), thrombodynamics (TD), thrombodynamics-4D (TD-4D)) were determined in PTS- and manually transported samples of 10 healthy volunteers.

There were no significant differences between the values of APTT, PT, TT or fibrinogen between the samples transported by PTS or manually. The results for LTA demonstrated increase in the collagen-induced aggregation (84 ± 7% versus 73 ± 5%), while the response to epinephrine was decreased (58 ± 20% versus 72 ± 7.4%). Flow cytometry-based platelet function test showed a pre-activation of platelets by PTS-transportation while all integral assays of coagulation tested in the present study (TEG, TGT, TD, TD-4D) demonstrated a hypercoagulation shift.

Transportation by PTS caused significant shifts in parameters of functional and integral assays that exceeded parameter variation values and sometimes even were comparable to normal ranges. The results obtained in this study indicate that using of PTS for such assays may cause sufficient alterations of results and can lead to patient's mistreatment.

The PFA-100 platelet function analyser simulates high-shear platelet function; however, the relative importance of the high shear rates alone has not been examined in this system. Normal blood was analysed by the PFA-100 using modified cartridges that contained a blank membrane lacking the usual platelet agonists (collagen/epinephrine or collagen/ADP) thus isolating the effects of shear stress alone. We found evidence of platelet activation with significant increases in platelet-leucocyte aggregates. There was no significant change in surface CD62P nor PAC-1 expression. A degree of platelet activation occurs in the PFA-100 due to shear stress alone.

Platelet activation has been suggested to play an important role in the pathogenesis of prethrombotic states and thus may be responsible for decompression illness during compressed air (scuba) diving. To investigate the effect of physical, mental, and environmental stress on platelet activation during immersion in ice-cold water, we examined 10 male breath-hold divers (BHD), 10 elite BHD (eBHD), and 10 scuba divers during immersion in an ice-covered lake at moderate altitude. Platelet activation was examined by surface expression of activation-dependent glycoproteins CD62p, CD63, and CD42a with flow cytometry 10 min before and 1 min and again 24 h after diving. Plasma epinephrine level was also measured. In addition, the relationship between the activated platelets and the epinephrine level was evaluated. The percentage of platelet activation increased from 2.1 +/- 0.4 to 5.7 +/- 0.3, 1.8 +/- 0.3 to 12.9 +/- 0.8, and 3.7 +/- 0.9 to 31.2 +/- 0.8 in BHD, eBHD, and scuba divers, respectively. The percentage of platelet activation returned to pre-immersion levels in BHD and eBHD divers 24 h after diving, but was still higher in scuba divers. A positive relationship exists between the plasma epinephrine level and the percentage of the platelet activation. This study suggests that physical and mental stress enhance platelet activation during diving in ice-cold water.

BACKGROUND

The heparan sulfate proteoglycan syndecan-1 (CD138) was shown to regulate inflammatory responses by binding chemokines and cytokines and interacting with adhesion molecules, thereby modulating leukocyte trafficking to tissues. The objectives of this study were to examine the expression of syndecan-1 and its role in leukocyte recruitment and chemokine presentation in the microcirculation underlying the parietal peritoneum.

METHODS

Wild-type BALB/c and syndecan-1 null mice were stimulated with an intraperitoneal injection of Staphylococcus aureus LTA, Escherichia coli LPS or TNFα and the microcirculation of the parietal peritoneum was examined by intravital microscopy after 4 hours. Fluorescence confocal microscopy was used to examine syndecan-1 expression in the peritoneal microcirculation using fluorescent antibodies. Blocking antibodies to adhesion molecules were used to examine the role of these molecules in leukocyte-endothelial cell interactions in response to LTA. To determine whether syndecan-1 co-localizes with chemokines in vivo, fluorescent antibodies to syndecan-1 were co-injected intravenously with anti-MIP-2 (CXCL2), anti-KC (CXCL1) or anti-MCP-1 (CCL2).

CONCLUSIONS

Syndecan-1 was localized to the subendothelial region of peritoneal venules and the mesothelial layer. Leukocyte rolling was significantly decreased with LPS treatment while LTA and TNFα significantly increased leukocyte adhesion compared with saline control. Leukocyte-endothelial cell interactions were not different in syndecan-1 null mice. Antibody blockade of β2 integrin (CD18), ICAM-1 (CD54) and VCAM-1 (CD106) did not decrease leukocyte adhesion in response to LTA challenge while blockade of P-selectin (CD62P) abrogated leukocyte rolling. Lastly, MIP-2 expression in the peritoneal venules was not dependent on syndecan-1 in vivo. Our data suggest that syndecan-1 is expressed in the parietal peritoneum microvasculature but does not regulate leukocyte recruitment and is not necessary for the presentation of the chemokine MIP-2 in this tissue.

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-associated morbidity and mortality. Activated platelets have important roles in TRALI and CD62P was identified to be an important indicator of platelet activation. However, the precise roles of CD62P in TRALI have remained elusive. The present study assessed CD62P accumulation during storage of apheresis platelet concentrates (A‑Plts) and established a mouse model of TRALI to further investigate the roles of CD62P in TRALI. The results showed that the CD62P concentration in A‑Plts was increased with the storage time. Mice were treated with monoclonal major histocompatibility complex (MHC)‑1 antibody to induce TRALI. The murine model of TRALI was successfully established as evidenced by pulmonary oedema, accompanied by decreased clearance of bronchoalveolar lavage fluid (BALF), increased pulmonary and systemic inflammation, elevated lung myeloperoxidase (MPO) activity as well as increased pulmonary and systemic coagulation in the TRALI group compared with those in the control group. To further determine the role of CD62P in TRALI, mice were treated with anti‑CD62P antibody to knockdown CD62P in vivo. It was found that pulmonary oedema, BALF clearance, pulmonary and systemic inflammation, MPO activity as well as pulmonary and systemic coagulation were decreased in the TRALI + anti‑CD62P antibody group compared with those in the TRALI + isotype antibody group. The present study supported the notion that CD62P is involved in mediating TRALI and may provide an important molecular basis for enhancing the clinical safety and effectiveness of platelet transfusion.

Hemostasis in preterm newborns is characterized by low reserve functional capacity with special reference to the presence of such risk factors as asphyxia or infection. Platelets play vitally important role in hemostasis. Expression of CD62P is a marker of stimulated or activated blood platelets. The study involved a group of 16 preterm newborns, five girls and 11 boys. DAKO QIFIKIT was applied to calculate the number of these antigens. The mean CD 62P expression was found to be 23,792 per platelet. Correlation was found between antigen density and gestational age r = 0.954, p = 0.01. Evident deficit of P-selectin on the surface of platelets in preterm newborns may be at least in part responsible for platelet dysfunction, with special reference to interaction between circulating leukocytes and combating infection.

BACKGROUND

This study was conducted to assess different cellular microparticles (MPs) in thrombocytopenic human immunodeficiency virus type 1 and their significance as disease activity markers.

METHODS

Thirty-five thrombocytopenic human immunodeficiency diseases and 25 healthy controls with matched age and sex were selected. Viral load was quantitated by COBAS real-time polymerase reaction (PCR) assessment of absolute T-cell subsets CD4, CD8 as a disease progress marker. Platelet MPs, platelet-derived monocyte MPs (CD42a, CD61), erythrocyte MP (CD235a), monocytic MP (CD14), and platelet activity MPs (CD62P, PAC-1) were assessed by multicolor flow cytometry FACSCalibur, while platelet functions were assessed by platelet function analyzer (PFA-100). CD42a, CD61, and platelet activity index represented by PAC-1 and CD62.

RESULTS

P-selectin in HIV-infected patient samples were significantly greater (P < 0.001) than among controls. There was a negative correlation between the proportion of PAC-1 and CD62 P-selectin-positive MPs and levels of CD4(+) T-cell counts (r = -0.403, P = 0.016; r = -0.438, P = 0.008), respectively. There was a negative correlation between collagen-ADP and levels of CD4(+) T-cell counts (r = -0.368, P = 0.03). There was a significant high expression level of CD14 monocyte MPs in patients than controls (P < 0.0001), overexpression of CD235a (P < 0.0001), and no correlation between CD14 and CD4, whereas there was a significant negative correlation with CD235a (r = -0.394, P = 0.019). A linear regression analysis of CD4 as a disease progression marker with other variable indicators in HIV patients showed that CD235a could be the most sensitive predictor similar to CD4.

CONCLUSIONS

Different cellular MPs and platelets activated in HIV patients could have a role in thrombotic events in these patients.

Eicosapentaenoic acid (EPA) has been widely accepted to have antiatherosclerotic effects. The aim of this study was to investigate the antiplatelet effect of EPA combined with acetylsalicylic acid (ASA) following stent implantation. Eighteen patients who had undergone coronary stent implantation at least 8 months previously were included. All patients were given EPA ethyl ester (EPA-E) 1.8 g/day in addition to ASA 100 mg/day for 12 weeks. After the treatment, the plasma EPA/arachidonic acid (AA) ratio increased significantly from 0.40 ± 0.2 to 1.08 ± 0.39 (P < 0.001). There were no changes in the maximum platelet aggregation (MPA) induced by adenosine diphosphate (5 and 20 µmol/L), AA (0.3 and 0.5 mg/mL), or collagen (2 and 4 µg/mL). Furthermore, no significant differences were observed in the expression of PAC-1 and CD62P on the platelet surface membranes or in the soluble P-selectin concentration. With further analysis, a significant negative correlation was found between collagen (2 µg/mL)-induced MPA and plasma EPA/AA ratio (r = -0.507, P = 0.032). The patients were then divided into 2 groups according to the median EPA/AA ratio value of 0.92. In the high EPA/AA ratio group (n = 10), collagen-induced MPA was significantly suppressed after EPA-E administration (45.3 ± 15.9 versus 39.0 ± 16.3, P = 0.033). In contrast, there were no significant changes in platelet aggregation (56.0 ± 9.8 versus 57.1 ± 11.4, P = 0.745) in the low EPA/AA ratio group (n = 8). EPA treatment had a potential to suppress collagen-induced platelet aggregation in patients with a high plasma EPA/AA ratio.

BACKGROUND

Orengedokuto, a Kampo medicine, is used to treat patients with hypertension and cerebrovascular disease in Japan. One of its effects is thought to be antiplatelet action, but the mechanisms involved are unclear. Therefore, we investigated the effects of Orengedokuto on platelet aggregation and activation.

METHODS

Platelet aggregation was determined by measuring light transmission (optical density [OD]) and light scattering intensity. Platelet activation was assessed by flow-cytometric determination of PAC-1+ and CD62P+ platelets. For the in vitro study, blood samples were obtained from 45 patients with cerebral infarction (chronic stage) and 27 magnetic resonance imaging-proven control subjects. Furthermore, Orengedokuto was administered to 10 patients with cerebral infarction for up to 12 months, and its effects on platelet aggregation and activation were evaluated.

RESULTS

Orengedokuto dose-dependently inhibited agonist-induced platelet aggregation. In vitro, the OD% (mean +/- SD) after stimulation with 2 mumol/L adenosine diphosphate was decreased from 54.4 +/- 21.0 to 16.0 +/- 14.2 (P < .01) in patients, and from 56.8 +/- 26.9 to 19.8 +/- 18.9 (P < .01) in control subjects (1000 mug/mL Orengedokuto). Similarly, the OD% after 0.5 mug/mL collagen stimulation was decreased from 98.3 +/- 37.0 to 24.8 +/- 27.9 (P < .01) in patients, and from 79.2 +/- 13.8 to 21.5 +/- 21.9 (P < .01) in the control subjects. In the clinical study, platelet aggregation was also significantly decreased (P < .05). Agonist-induced platelet activation was not significantly inhibited by Orengedokuto in vitro, but spontaneous platelet activation in patients after oral administration was reduced from 31.0 +/- 18.3 to 14.2 +/- 8.7 (PAC-1+) and from 11.3 +/- 7.8 to 5.1 +/- 3.9 (CD62+) (P < .05).

CONCLUSIONS

Our results demonstrated inhibitory activity of Orengedokuto on both platelet aggregation and activation at a clinically relevant dose.

BACKGROUND

Platelets play a crucial role in the pathogenesis of acute coronary syndromes (ACS). The efficacy of antiplatelet treatment is pivotal in the success of percutaneous coronary intervention (PCI) performed in patients with ACS.

OBJECTIVE

The aim of the study was to investigate the effects of clopidogrel with or without abciximab on the expression of platelet surface receptors and platelet function in patients with ST-segment elevation myocardial infarction (STEMI) undergoing PCI.

METHODS

Thirty patients with STEMI were included in the study. During acute primary coronary intervention, patients received aspirin (acetylsalicylic acid) and clopidogrel in a loading dose of 300mg. Clopidogrel was the only antiplatelet therapy used by nine patients (group B). Twenty-one patients (group A) received additional abciximab. Blood samples were collected and analyzed twice: before and up to 22 hours after administration of antiplatelet therapy. The platelet aggregation was established as primary platelet-related hemostasis (closure time [CT] assessed using the PFA100 system). The absolute number of platelet surface antigens as CD41a, CD42a, CD42b, CD61, and CD62P were determined by flow cytometry analysis.

RESULTS

The study revealed a statistically significant increase in CT induced by adenosine diphosphate and adrenaline (epinephrine) +130 seconds (p < 0.0001) and +94 seconds (p < 0.0001), respectively, in group A patients post-therapy. While in group B the parameters of CT did not change after treatment. In addition, the absolute number of CD41a antigens (glycoprotein [GP] IIb/IIIa) increased significantly after treatment in group A. No significant changes were observed after treatment in the expression of CD62P (P-selectin) antigens in either treatment group. There was a significant reduction in the percentage of CD62P-positive platelets in group B after antiplatelet therapy.

CONCLUSIONS

The absolute number of GP IIb/IIIa receptors increases and platelets are not activated up to 12 hours after cessation of abciximab therapy. Treatment of STEMI patients undergoing PCI with a loading dose of clopidogrel reduces the percentage of active platelets but does not influence the CT.

BACKGROUND

Certain patient subpopulations do not respond to antithrombotic effects of aspirin and different approaches have been proposed to detect and define this so-called aspirin resistance. In this study, a methodological and clinical evaluation of a flow cytometric method for the detection of aspirin-induced inhibition of platelet cyclooxygenase (COX) is presented.

METHODS

Platelet CD62p-antigen (P-selectin) expression was determined by flow cytometry after incubating diluted platelet rich plasma (PRP) with arachidonic acid (ARA). After establishing the method's technical characteristics, it was used to investigate 114 individuals (70 patients with atherosclerotic vascular disease under long-term medication of 100 mg aspirin daily, 29 age-matched patients with vascular disease without anti-platelet medication and 15 healthy volunteers). Data were compared to those obtained by the PFA-100 platelet function analyzer.

RESULTS

Imprecision was between 3.3% and 13%. Sample storage at room temperature increased baseline activity of platelets already after 2 h. After ARA stimulation, the proportion of CD62p-positive platelets was considerably lower in aspirin-treated patients than in controls (median [lower-upper quartile]: 4% [3-6] vs. 50% [29-68], p<0.001). Only one aspirin-treated patient (1.5%) showed normal reactivity to ARA. In contrast to flow cytometry, PFA-100 analysis yielded normal results in 17% of aspirin-treated patients.

CONCLUSIONS

The presented flow cytometric method can be used to monitor aspirin-induced inhibition of platelet COX. Aspirin resistance defined as failure to inhibit platelet COX is a rare phenomenon suggesting that most cases of aspirin resistance detected using the PFA-100 are caused by COX-independent mechanisms.