Maximum Aggregation Rate Research Articles

Core bioactive components promoting blood circulation in the traditional Chinese medicine compound xueshuantong capsule (CXC) based on the relevance analysis between chemical HPLC fingerprint and in vivo biological effects.

Compound xueshuantong capsule (CXC) is an oral traditional Chinese herbal formula (CHF) comprised of Panax notoginseng (PN), Radix astragali (RA), Salvia miltiorrhizae (SM), and Radix scrophulariaceae (RS). The present investigation was designed to explore the core bioactive components promoting blood circulation in CXC using high-performance liquid chromatography (HPLC) and animal studies. CXC samples were prepared with different proportions of the 4 herbs according to a four-factor, nine-level uniform design. CXC samples were assessed with HPLC, which identified 21 components. For the animal experiments, rats were soaked in ice water during the time interval between two adrenaline hydrochloride injections to reduce blood circulation. We assessed whole-blood viscosity (WBV), erythrocyte aggregation and red corpuscle electrophoresis indices (EAI and RCEI, respectively), plasma viscosity (PV), maximum platelet aggregation rate (MPAR), activated partial thromboplastin time (APTT), and prothrombin time (PT). Based on the hypothesis that CXC sample effects varied with differences in components, we performed grey relational analysis (GRA), principal component analysis (PCA), ridge regression (RR), and radial basis function (RBF) to evaluate the contribution of each identified component. Our results indicate that panaxytriol, ginsenoside Rb1, angoroside C, protocatechualdehyde, ginsenoside Rd, and calycosin-7-O-β-D-glucoside are the core bioactive components, and that they might play different roles in the alleviation of circulation dysfunction. Panaxytriol and ginsenoside Rb1 had close relevance to red blood cell (RBC) aggregation, angoroside C was related to platelet aggregation, protocatechualdehyde was involved in intrinsic clotting activity, ginsenoside Rd affected RBC deformability and plasma proteins, and calycosin-7-O-β-D-glucoside influenced extrinsic clotting activity. This study indicates that angoroside C, calycosin-7-O-β-D-glucoside, panaxytriol, and protocatechualdehyde may have novel therapeutic uses.

Steroidal saponins with induced platelet aggregation activity from the aerial parts of Paris verticillata

In order to utilize and protect the resources of Rhizoma Paridis rationally, we carried out a phytochemical investigation on the non-medicinal (aerial) parts of Paris verticillata that led to the isolation of fifteen steroidal saponins. Among them, three are new spirostanol saponins, named parisverticosides A–C (1–3), as well as one new cholestane glycoside, named parisverticoside D (4). Their structures were elucidated by extensive spectroscopic analysis and acid hydrolysis. The aglycone of compound 1 is a new spirostane and identified as (23S,24S,25S)-spirost-5-en-1β,3β,23, 24-tetraol. The selected isolates were evaluated for induced platelet aggregation activity and compound 5 showed 62% maximal platelet aggregation rate at the concentration of 300μg/mL.

Effect of Sheshang capsule on platelet function of rabbits bitten by Trimeresurus stejnegeri and its mechanism

To investigate the effect of the Sheshang capsule on coagulation of the rabbits bitten by Trimeresurus stejnegeri and its mechanism. The changes in platelet aggregation rate was observed after the establishment of rabbits model by subcutaneously injection with 0.75, 1.50, 2.25, and 3.00 mL/kg of Trimeresurus stejnegeri venom for 72 hours. Fifty New Zealand white rabbits were randomly divided into five groups, 10 rabbits in each group. Rabbit model was reproduced by subcutaneously injection with 0.75 mL/kg of Trimeresurus stejnegeri venom. The rabbits in sham group were injected with 0.75 mL/kg normal saline(NS). The rabbits were gavaged with 5, 10, 15 mL × kg⁻¹ × d⁻¹ of the Sheshang concoction to the low, intermediate and high dose groups respectively after 6 hours, and 10 mL × kg⁻¹ × d⁻¹ NS was fed in the sham group and model group. The platelet aggregation rate, platelet count (PLT), mean platelet volume (MPV), plateletcrit (PCT), platelet distribution width (PDW), cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) were determined after 1 week. (1) With the increase in the concentration of Trimeresurus stejnegeri venom, 1-min, 3-min, 5-min and maximum platelet aggregation rates showed a gradual declining trends. (2) Compared with the sham group, 5-min and maximum platelet aggregation rate in the model group were significantly decreased [35.5 (24.2, 42.5)% vs. 43.0 (38.2, 58.5)%, 39.5 (29.0, 45.0)% vs. 46.5 (39.2, 60.2)%, both P<0.05]. Compared with the model group, 5-min and maximum platelet aggregation rate in the intermediate dose group were significantly increased [44.0 (39.8, 45.0) % vs. 35.5 (24.2, 42.5) %, 45.5 (43.5, 46.2) % vs. 39.5 (29.0, 45.0) %, both P<0.05]. There was no significant difference in platelet aggregation rate among the other groups. Compared with the sham group, PLT count in model group was obviously reduced (410.3 ± 155.3 × 10⁹/L vs. 724.5 ± 220.7 × 10⁹/L, P<0.01), so as MPV and PCT done [MPV: 5.11 ± 1.09 fl vs. 6.34 ± 1.16 fl, P<0.01; PCT: 21.9 (18.6, 26.8) % vs. 34.8 (24.8, 45.4) %, P<0.05]. Compared with the model group, PLT and PCT in the low, intermediate and high dose groups were significantly increased [PLT: 702.4 ± 166.3 × 10⁹/L, 648.5 ± 160.2 × 10⁹/L, 789.3 ± 86.2 × 10⁹/L vs. 410.3 ± 155.3 × 10⁹/L, PCT: 38.8 (35.7, 42.9)%, 36.0 (29.8, 44.4)%, 43.1 (40.5, 48.8)% vs. 21.9 (18.6, 26.8)%, all P<0.01], and MPV in the intermediate dose group was significantly increased (6.26 ± 1.05 fl vs. 5.11 ± 1.09 fl, P<0.01). There was no significant difference in PDW among groups (P>0.05). Compared with the sham group, cAMP (47.57 ± 12.76 nmol/L vs. 36.67 ± 10.54 nmol/L) and PKA (14.68 ± 5.80 μg/L vs. 9.23 ± 4.05 μg/L) in the model group were significantly increased (both P<0.05). Compared with the model group, cAMP and PKA of each dose group were decreased, while cAMP in low dose group [(36.33 ± 11.08) nmol/L] and PKA in the intermediate dose group [(10.21 ± 5.31) μg/L] were significant decreased (both P<0.05). In the range of experimental concentration (0-3 mL/kg), the higher the concentration, and the stronger the inhibition of platelet aggregation rate was. The Sheshang capsule can raise platelet aggregation rate and PLT, increase MPV and PCT, and act against inhibition of platelet aggregation effect of the venom, thus improve the haemostatic function of platelet. Sheshang capsule can be used to treat the coagulopathy induced by Trimeresurus stejnegeri venom through regulating cAMP/PKA pathways.

Data Aggregation Routing for Rechargeable Wireless Sensor Networks in Forest Monitoring

In rechargeable wireless sensor networks (r-WSNs), higher data transmitted efficiency is required because sensor have to operate in a very low duty cycle owing to sporadic availability of energy. In r-WSNs, Data collected by many sensors is based on common phenomena, and hence there is a high probability that this data has some redundancy. In this work, we address the problem of jointly optimizing data aggregation and routing so that the network workload can be maximized. Establish the relationship model between data aggregation rate and throughput, so that the balanced was set up between the data aggregation rate and maximum network data traffic. Through the use of optimal candidate sample allocation, the algorithm can coverage efficiently and can make the maximum data aggregation rate flow to the network while maximizing network workload. Simulations are carried out to show that the proposed algorithm can significantly improve workload.

Abstract 576: ABO Blood Group and Platelet Aggregation

Background: ABO blood groups have been linked to coronary thrombosis, with non-O blood groups at higher risk of thrombosis. ABO blood group antigens are expressed on platelet glycoproteins, including the IIb fibrinogen receptor, and may affect platelet function via glycan modifications. We hypothesized that non-O blood groups would demonstrate higher levels of platelet aggregation compared to type O blood group. Methods: Healthy, non-smoking subjects were recruited to a protocol investigating glycan modification of platelets. Ex vivo platelet aggregation was assessed by light transmission aggregometry of platelet-rich plasma in dose-response to collagen (0.04-0.2 mg/mL) and thrombin receptor activating peptide (TRAP) (1-5 μmol). Maximal platelet aggregation data, aggregation rate and lag time were compared at each concentration across blood groups A, B, AB and O by ANOVA testing. Results: A total of 91 subjects were recruited (ABO types; 32 A, 16 B, 8 AB, 35 O). The average age of the subjects was 31 years, 58% were Caucasian and 61% were female. There were no significant differences in age, race and gender between ABO blood groups. For collagen concentrations ranging from 0.04-0.2 mg/mL, there was no significant difference in mean platelet aggregation, rate of aggregation and lag time between blood groups. For TRAP concentrations between 1-5 μmol, there was also no significant difference in mean platelet aggregation and rate of aggregation between blood groups. For TRAP at 2 μmol and 3 μmol, blood group AB demonstrated a longer lag time compared to blood groups A, B, and O (TRAP 2 μmol; 13 sec type AB vs 5.21 sec type A, 4.18 sec type B, 3.57 sec type O, TRAP 3 μmol; 9.12 sec type AB vs 3.34 sec type A, 4.31 sec type B, 2.65 sec type O) but these secondary analyses were of marginal significance after consideration of multiple testing. Conclusion: These data for ex vivo platelet aggregation dose-response to collagen and TRAP do not support significant differences in platelet function by ABO blood type. Further studies with larger sample sizes and of specific platelet glycoprotein functions are required to address potential subtle influences of ABO glycans on platelet reactivity.

Prognostic significance of thrombocytosis, platelet parameters and aggregation rates in epithelial ovarian cancer

The aim of this study is to investigate the impact of preoperative platelet counts, parameters and aggregation rates (maximal aggregation rate: MAR) on prognosis in patients with epithelial ovarian cancer (EOC). Preoperative platelet count, parameters and MAR in 182 EOC patients, 122 patients with benign ovarian tumor and 150 healthy women were retrospectively analyzed. The correlation between thrombocytosis, platelet parameters, MAR and clinicopathological factors were evaluated in EOC. Forty-five (24.73%) EOC patients had preoperative thrombocytosis in this study. The mean platelet count in the EOC group was significantly higher than that of benign and healthy groups (P < 0.001). The MAR in the EOC group was significantly higher than that in the healthy group (71.96% vs 57.03%, P = 0.025). The platelet parameters (mean platelet volume, platelet distribution width, thrombocytocrit and large platelet ratio) were consistently higher in the EOC group than those in the benign and healthy groups, but the differences were insignificant. A significant correlation between thrombocytosis and MAR was observed in EOC patients (r = 0.694, P < 0.001). EOC patients with thrombocytosis were found to have significantly higher grade (P = 0.048), more advanced stage (P = 0.045), higher level carbohydrate antigen-125 (P = 0.007) and greater likelihood of suboptimal cytoreduction (P = 0.035). EOC patients with both thrombocytosis and high MAR were found to have shorter progression-free survival (P = 0.001)and overall survival (P = 0.004). The combination of thrombocytosis and MAR, as well as stage and optimal cytoreduction, retained significance as an independent prognostic factor for overall survival. Thrombocytosis, accompanied by increasing of platelet aggregation rates, is associated with more aggressive tumor biology in EOC. The combination of thrombocytosis and MAR is an independent negative prognostic factor for overall survival in EOC patients.

Curcumin Alters the Pharmacokinetics of Warfarin and Clopidogrel in Wistar Rats but Has No Effect on Anticoagulation or Antiplatelet Aggregation

This study examined the effects of curcumin on the pharmacokinetic and pharmacodynamic properties of warfarin and clopidogrel in Wistar rats. Results showed that oral administration of curcumin at 25 mg/kg, 50 mg/kg, and 100 mg/kg for 7 days had no substantial effects on the pharmacodynamics of warfarin and clopidogrel in this animal model. However, oral administration of 100 mg/kg curcumin for 7 days significantly increased the AUC0-∞ and Cmax of the two drugs (by × 1.6 and × 1.5, respectively, for warfarin, and × 1.61 and × 1.81, respectively, for clopidogrel carboxylic acid). However, compared to warfarin alone, different doses of curcumin combined with warfarin had no effects on the prothrombin time in rats. Similarly, a combination of curcumin and clopidogrel had no significant effect on the maximum platelet aggregation rate of rats compared with the use of clopidogrel alone. This work demonstrated that preadministration of 100 mg/kg curcumin affected the pharmacokinetics of warfarin and clopidogrel but had no effect on pharmacodynamic parameters such as anticoagulation rate and antiplatelet aggregation.

Evaluation of a new method and instrument for detection platelet aggregation function and its clinical application

This study was purpose to evaluate a new method and instrument for detecting platelet aggregation function, establish the reference intervals for PL-11 platelet analyzer, and evaluate its clinical application. The evaluation was based on the guidelines of Clinical and Laboratory Standards Institute (CLSI or NCCLS) and Clinical Laboratory Improvement Amendment 88. Intravenous blood samples anticoagulated with sodium citrate were detected by PL-11 platelet analyzer. The reference intervals were defined after statistic analysis. The clinical diagnostic significance of the PL-11 platelet analyzer was evaluated by testing the change rate of platelet maximum aggregation rate (MAR) of acute cerebral infarction (ACI) patients in the department of Neurology who took clopidogrel 7 d before and after. The result showed that all the parameters meet the standard of CLIA'88. The platelet MAR of 247 healthy volunteers which was induced by PLR-06, PLR-07, PLR-09 and PLR-10, was detected by the PL-11 platelet analyzer, respectively. The MAR is 58.8 ± 10.1 (%), 61.2 ± 11.8 (%), 51 ± 10.2 (%), 53.1 ± 9.2 (%), respectively. The MAR of ACI patients is significantly lower than that after taking clopidogrel. It is concluded that the PL-11 platelet analyzer is an ideal platelet function detector for early warning and diagnosis of thromboembolic disease, which is worthy to be extended and applied.

Light transmittance aggregometry with non-adjusted PRP is more suitable for clinical laboratory monitoring antiplatelet therapy

Objective In this study,maximum platelet aggregation rate of Light transmittance aggregometry (LTA) for coronary heart disease (CHD) patients taking antiplatelet drug and patients without antiplatelet therapy was measured in non-adjusted and platelet count-adjusted platelet-rich plasma (PRP).The aim of this study is to compare which method is superior in evaluation of antiplatelet drug effect. Methods This is a methodology comparative research.560 CHD outpatients and inpatients that visited Beijing Anzhen Hospital of the Capital University of Medical Sciences from May to June,2012 were chosen,who were treated with aspirin monotherapy,or patients on combination therapy with aspirin and clopidogrel,as well as patients without antiplatelet therapy.LTA was performed in non-adjusted (improved method) and platelet count (200×109/L) -adjusted PRP (original method),using 6μmol/L adenosine diphosphate (ADP) and 0.5 mmol/L arachidonic acid (ARA) as agonists.The maximum aggregation rates in 5 min were detected,and consistency and differences of the two methods were compared. Results There is no statistically significant correlation between maximum aggregation rate and platelet count in PRP with 6μmol/L ADP or 0.5 mmol/L ARA as agonists in all subgroups including aspirin monotherapy,combination therapy with aspirin and clopidogrel and patients without antiplatelet therapy (-0.21≤r≤0.111,P>0.05).The maximum aggregation rate using ADP as agonists in original method is decreased compared with improved method,there is statistically significant difference in all subgroups including patients without antiplatelet therapy,aspirin monotherapy,combination therapy with aspirin and clopidogrel less than one week and more than one week.The variability of platelet aggregation rate using ADP as agonists with improved method is lower than that with original method in all subgroups.Yet the maximum aggregation rates using ADP as agonists with improved method and original method correlate well with each other in all subgroups (r=0.78,0.73,0.40,0.71,P<0.01).In the subgroup of subjects without antiplatelet therapy using ARA as agonist,platelet aggregation rate is decreased in original method compared with improved method,there is statistically significant difference,and the variability of the aggregation rate with improved method is also lower than that with original method,ranging from 62%-98% relative to 5%-89%.The decrease of aggregation rate using ARA as agonist for patients taking antiplatelet drug compared with patients without antiplatelet therapy can be detected both with improved method and original method. Conclusion Non-adjusted PRP in LTA is more convenient and time-saving,and it also means less effects on platelet in vitro.Therefore,non-adjusted PRP is more suitable for monitoring efficacy of antiplatelet therapy in clinical laboratory.(Chin J Lab Med,2013,36:405-409) Key words: Platelet aggregation inhibitors; Platelet count; Platelet aggregation; Nephelometry and turbidimetry; Treatment outcome

PH-Dependent Aggregation and Disaggregation of Native β-Lactoglobulin in Low Salt

The aggregation of β-lactoglobulin (BLG) near its isoelectric point was studied as a function of ionic strength and pH. We compared the behavior of native BLG with those of its two isoforms, BLG-A and BLG-B, and with that of a protein with a very similar pI, bovine serum albumin (BSA). Rates of aggregation were obtained through a highly precise and convenient pH/turbidimetric titration that measures transmittance to ±0.05 %T. A comparison of BLG and BSA suggests that the difference between pHmax (the pH of the maximum aggregation rate) and pI is systematically related to the nature of protein charge asymmetry, as further supported by the effect of localized charge density on the dramatically different aggregation rates of the two BLG isoforms. Kinetic measurements including very short time periods show well-differentiated first and second steps. BLG was analyzed by light scattering under conditions corresponding to maxima in the first and second steps. Dynamic light scattering (DLS) was used to monitor the kinetics, and static light scattering (SLS) was used to evaluate the aggregate structure fractal dimensions at different quench points. The rate of the first step is relatively symmetrical around pHmax and is attributed to the local charges within the negative domain of the free protein. In contrast, the remarkably linear pH dependence of the second step is related to the uniform reduction in global protein charge with increasing pH below pI, accompanied by an attractive force due to surface charge fluctuations.

Relationship of CYP2C19*2 and CYP2C19*3 Gene Polymorphism with Clopidogrel Response Variability and Recurrent Cardiovascular Events in Chinese Patients Undergoing Percutaneous Coronary Intervention

Background/Aims: The study was conducted to assess the influence of CYP2C19 polymorphisms on clopidogrel response variability and recurrent cardiovascular (CV) events in Chinese patients undergoing percutaneous coronary intervention (PCI). Methods: Platelet aggregation induced by 5 and 20 µmol/l adenosine diphosphate was measured in 109 patients at baseline, 12 h and 36 h after loading with 300 mg of clopidogrel. The primary end point was recurrent CV events, and the follow-up was scheduled at 1, 3, 6 and 12 months after PCI. The polymorphisms of CYP2C19*2 and CYP2C19*3 were genotyped by DNA sequencing analysis. Results: The maximal aggregation rates and inhibition of platelet aggregation among CYP2C19*1/*1, CYP2C19*1/*2 or *3 and CYP2C19*2/*2 or *3 genotypes were significantly different at 12 and 36 h after clopidogrel loading dose administration. Multiple linear regression analysis demonstrated that CYP2C19*2 and CYP2C19*3 might be predictors of clopidogrel response variability. During the 12-month follow-up, recurrent CV events occurred in 21 (19.63%) patients, and there were 5 (6.47%) deaths, 3 (2.80%) cases of ischemic stroke and 14 (13.1%) cases of acute coronary syndrome. Carriers of at least one CYP2C19 loss-of-function allele (*1/*2 or *3, *2/*2 or *3) incurred a 3.65-fold increase (95% CI 1.07–12.38; p = 0.038) in the risk of recurrent CV events 1 year after PCI compared to noncarriers (*1/*1). Conclusion: Polymorphisms in CYP2C19*2 and CYP2C19*3 contribute to variabilities in clopidogrel responsiveness. Patients carrying at least one CYP2C19 loss-of-function allele (CYP2C19*2, *3) are associated with an increased risk of recurrent CV events undergoing PCI.

Chronic kidney disease — Is it a true risk factor of reduced clopidogrel efficacy in elderly patients with stable coronary artery disease?

BackgroundChronic kidney disease (CKD) is an established predictor of recurrent ischemic events in patients with coronary artery disease (CAD). This association has been partially ascribed to high post-treatment platelet reactivity (HPPR) according to platelet function testing. However, the influencing factors of HPPR are assay-dependent, and the relevant data of elderly patients with stable CAD are absent. Patients and Methods310 elderly patients (>80years of age) with stable CAD taking prolonged maintenance clopidogrel (75mg/day) were studied. Maximal platelet aggregation rate (MPA%) with light transmittance aggregometry and Platelet Reactive Units (PRU) with VerifyNow (VN) P2Y12 system were obtained. Markers of platelet activation, including PAC-1 and CD62P, were also determined. ResultsPatients on different stages of CKD presented similar MPA% and expression of PAC-1 and CD62P. Although severe CKD patients were more likely to present HPPR identified by VNP2Y12 (odds ratio: 1.85, p=0.038), multiple logistic regression diminished this effect (adjusted odds ratio: 1.19, p=0.642), and revealed anemia as a possible predictor of HPPR (adjusted odds ratio: 5.92, p=0.001). However, in a parallel way, hemoglobin correlated with baseline PRU values as well as with post-treatment values (r=−0.624 and r=−0.463, respectively, p<0.001). Association between hemoglobin and PRU inhibition rate was not found. Moreover, hemoglobin exerted no influence on MPA% at all. ConclusionCKD is not necessarily associated with reduced antiplatelet effects of clopidogrel in elderly patients with stable CAD taking prolonged maintenance clopidogrel, and the seemingly influence of CKD on HPPR assessed by VNP2Y12 assay may be due to the artifactual effect of hemoglobin on VNP2Y12.

The Effects of Aminoglycoside Antibiotics on Platelet Aggregation and Blood Coagulation

To investigate the effects of different aminoglycoside antibiotics on platelet aggregation and blood coagulation, as well as the underlying mechanisms. Blood samples were collected and prepared as platelet-rich plasma and platelet-poor plasma samples. Then assigned into different groups for the following antibiotics treatments: gentamicin, streptomycin, etimicin, amikacin, and kanamycin, as group 0 mg/L, group 30 mg/L, group 91mg/L, and group 910 mg/L for each drugs. The maximum platelet aggregation rate induced by adenosine diphosphate, expression levels of CD62p and FIB-R, prothrombin time, activated partial thromboplastin time, thrombin time, and fibrinogen were measured. The sodium citrate and sodium heparin were used in whole blood tests for the whole blood coagulation time as well as the Ca(2+) in blood plasma. Amikacin and gentamicin could inhibit the aggregation of platelets, which contributed to the whole blood clotting disorder. Amikacin and gentamicin might inhibit the platelet aggregation by blocking the activation and release of FIB-R or probably the inhibition of endogenous clotting factor as well. This effect was not dependent on calcium ions.

Efficacy of dual antiplatelet therapy combined with Naoxintong Capsules (脑心通胶囊) following coronary microembolization induced by homologous microthrombi in rats

To evaluate the effificacy of dual antiplatelet therapy combined with Naoxintong Capsule ([see text], NXTC) in a rat model of coronary microembolization (CME). A total of 95 rats were randomly divided into 6 groups: control, sham-operation, CME model, NXTC, dual antiplatelet (clopidogrel and aspirin) intervention (DA), and NXTC combined with DA (NDA) groups. The complete data in 69 rats were obtained. The number of CME, myocardial apoptosis rate, bleeding time, clotting time, and adensosine diphosphate (ADP)-induced platelet aggregation were assessed. Compared with the CME group, the number of CME and myocardial apoptosis rates were signifificantly decreased in the NXTC, DA, and NDA groups (P <0.01). Compared with other intervention groups, the number of CME and myocardial apoptosis rates were the least in the NDA group (P <0.01), and the incidence of surgical bleeding was the highest in the DA group (P <0.01). Compared with the CME group, ADP-induced maximum platelet aggregation rate was significantly inhibited in the NXTC, DA, and NDA groups (P <0.01), both bleeding time and clotting time were signifificantly increased in the NXTC, DA, and NDA groups (P <0.01), while the above parameters were the highest in the DA group (P <0.05). The combination therapy of NXTC and DA enhanced the anti-CME effect of either therapy alone and reduced the risk of the DA therapy-associated bleeding, demonstrating an improved benefifit/ risk ratio in the rat model of CME.

Clopidogrel response variability and its correlation with recurrent cardiovascular events in Chinese patients undergoing percutaneous coronary intervention

ObjectiveThe present study was designed to explore response variability and its correlation with recurrent cardiovascular events in Chinese patients undergoing Percutaneous coronary intervention (PCI).MethodsPlatelet aggregation (5 and 20 μmol/l, ADP)...

English

Acid elution of platelets class I human leukocyte antigen (HLA) antigens is considered as a strategy for production of HLA-eluted platelets for clinical use. In this study, we investigated the effects of acid treatment for the removal of class I HLA antigens on platelet activation, apoptosis and aggregation, and to evaluate the optimal elution condition and the feasibility of clinical application of the acid-elution technique. In vitro apheresis platelets from healthy volunteers were treated with various PH levels the citric acid solution (pH = 2.0, 3.0, 5.0, 7.0) at 0&deg;C for 10 min. Expression of class I HLA antigens and P-selectin (CD62P) on platelet surface were analyzed by multicolor flow cytometry. The proportion of early apoptotic platelets was detected by Annexin V staining. The maximum platelet aggregation rate was determined by the electrical impedance aggregometry. Results showed that the expression of platelets class IHLA antigens decreased with the reduction of pH value accompanied by increase of CD62P expression and early apoptosis (Annexin V expression). When compared with phosphate buffered saline (PBS) treated platelets, platelets after elution with citric acid at pH 3.0 had significantly decreased expression of class IHLA antigens and the aggregation was not impaired, although the CD62P expression and early apoptosis were significantly increased. These results indicates that elution of platelets with citric acid at pH 3.0 can be use as an attempt to product HLA-eluted platelets for clinical use. &nbsp; Key words:&nbsp;Platelet, human leukocyte antigen (HLA), CD62P, apoptosis, acid elution.

Loading solution prevents activation damage of human platelets before lyophilization

The current study aims to optimize the compositions of platelet activation-inhibitors for a loading solution of lyophilizing protectants and to establish a series of perfect pretreatment methods for platelet lyophilization. The optimal combination of six kinds of inhibitors and loading solutions of lyophilizing protectants, including prostaglandin E1 (PGE1), adenosine, l-arginine, phyticacid, bivalirudin, and cilostazol, was analyzed using the orthogonal experimental design. The values of the expression rates of p-selectin (CD62p) and platelet membrane glyeoprotein (PAC-1), as well as of platelet and mean platelet volume (MPV), were selected as indices of platelet activation. The values of CD62p and Pac-1 induced by thrombin were determined as indices of platelet reactivity. The maximal aggregation and slide platelet aggregation test (SPAT) induced by the inducer were calculated as indices of the aggregation function of platelets. Level I of the loading condition factor had no adverse action on MPV, CD62p, PAC-1, SPAT, and the maximum platelet aggregation rate. Level II of factors PGE1, l-arginine, phycicacid sodium, and Bivalirudin could inhibit the activation of platelets and enable them to retain their function. The results show that the optimal solution compounding was the third group. The loading solution, which includes plasma, 1μM prostaglandin E1, 5mM l-arginine, 0.5mM phyticacid, and 0.5μM bivalirudin, could prevent the activation damage of platelets before lyophilization.

Effects of salivae miltiorrhizae liguspyragine hydrochloride and glucose injection (参芎葡萄糖注射液) on the levels of main platelet thrombin receptors in chronic haemodialysis patients

To investigate the effects of Salvia Miltiorrhiza Liguspyragine Hydrochloride and Glucose Injection (, SLGI) on the expression of platelet membrane receptors proteinase-activated receptor-1 (PAR1) and proteinase-activated receptor-4 (PAR4) in end-stage renal disease (ESRD) patients on chronic haemodialysis (HD). Eighty-six ESRD patients on HD (treated group) were treated with SLGI, 7 days as one therapeutic course, for two successive courses. The previous therapies were unchanged. Flow cytometry was used to assess the expression of platelet PAR1 and PAR4 in the patients, and turbidity method was used to determine the platelet maximum aggregation rate (MAR). Meanwhile, renal function was measured. The final data were compared with those before treatment and with those in the normal control group (54 healthy subjects). Compared with the normal control group, the expressions of PAR1 and PAR4 and platelet MAR in ESRD patients on HD was significantly higher before treatment (P=0.001, P=0.006, and P=0.008); after treatment with SLGI, the above indices in patients were remarkably decreased (P=0.036 and P=0.046), except PAR4 (P=0.067), but still higher than those in the normal control group, however, it was not statistically significant. (1) The overexpression of PAR1 and PAR4 might lead to increased platelet aggregation and this could be one of the reasons for the thrombotic events in ESRD patients on HD. (2) SLGI was able to down-regulate the expression of PAR1 in ESRD patients on HD, improve platelet function, and regulate platelet activation.

Clopidogrel Response Variability and Its Correlation with Early Recurrent Cardiovascular Events in Chinese Patients Undergoing Percutaneous Coronary Intervention

Background/Aims:Numerous studies conducted on Caucasian patients have reported that individual responsiveness to clopidogrel varies widely, whereas there are only a few published studies on the antiplatelet effect of clopidogrel therapy in Chinese patients undergoing percutaneous coronary intervention. The present study aimed to evaluate clopidogrel antiplatelet effects and their correlation with early recurrent cardiovascular (CV) events. Methods: Platelet aggregation (with 5 and 20 µmol/l ADP) and the expression of glycoprotein Ib and P-selectin were measured at baseline and 12 and 36 h after the clopidogrel loading dose in 111 consecutive patients. The primary outcome was a definite CV event. Results: There was marked interindividual variability in the drug response, as measured by platelet aggregation and P-selectin expression. The proportions of nonresponders at 12 and 36 h were 32 and 19%, respectively, with 5 µmol/l ADP, 38 and 28% with 20 µmol/l ADP, and 27 and 17% according to P-selectin expression. The maximal aggregation rates stimulated by 5 µmol/l ADP in nonresponders were significantly higher than those of the responders at 12 h (57.53 ± 14.24% vs. 33.91 ± 10.79%; p < 0.0001) and at 36 h (48.65 ± 15.46% vs. 30.31 ± 16.04%; p < 0.0001). During the 3-month follow-up period, 11 patients (32.4%) among the nonresponders, 2 patients (7.1%) among the low responders and none of the responders suffered a recurrent CV event (p < 0.0001). Conclusions: The antiplatelet effectiveness of clopidogrel has a wide interindividual variation, and nonresponsiveness to clopidogrel is associated with an increased risk of early recurrent CV events.

Influence of aortic dissection on the clotting-fibrinolysis system and platelet function

Coagulopathy is still a frequent complication in the surgical treatment of acute aortic dissection. This study was designed to clarify the influence of acute aortic dissection on the clotting-fibrinolysis system and platelet function. From January 1993 to December 1994 21 patients with proven Stanford type B aortic dissection underwent a series of tests and procedures at our institution. There were 6 women and 15 men, aged 37–74 years (mean 62 years). All patients were admitted within 14 days of onset of dissection. No patient had complications requiring surgery and none died during the observation period. We observed a severe inflammatory reaction with activation of the clotting-fibrinolysis system immediately after onset of dissection. The platelet maximum aggregation rates were also decreased transiently after onset of the dissection. D-dimer values remained elevated throughout, the observation period. A rational approach to the surgical treatment of acute aortic dissection should involve coping with its activated clotting-fibrinolysis system and platelet dysfunction in addition to tissue friability.