Platelet Aggregation Pattern on Light Transmission Aggregometry Among Malaysian Healthy Individuals

@#Introduction: Platelet aggregation test using light transmission aggregometry (LTA) is considered as the gold standard for evaluation of platelet function. Variations of platelet aggregation had been reported in apparently healthy individuals whereby a normal cut–off value established locally is highly recommended. This study aims to determine the platelet aggregation pattern and the preliminary findings on reference values for multiple agonists–induced platelet aggregation among Malaysian healthy individuals in a single centre. Method: A total number of 63 informed consented healthy individuals consisted of Malay, Chinese and Indian were recruited among staff and blood donors at National Blood Centre, Kuala Lumpur. Platelet aggregation was measured using LTA against adenosine diphosphate 10 µM (ADP10), collagen 0.19 mg/mL (COL), ristocetin 1.5 mg/mL (RIS), arachidonic acid 1 mM (AA) and epinephrine 10 µM (EPI). Results were expressed as percent final aggregation (%FA). Reference values were calculated from mean±2SD. Results: Age, gender and ethnic groups had no significant effect on platelet aggregation. A variability of platelet aggregation response to EPI was observed among the healthy individuals. Ten of 33 respondents (30%) had impaired aggregation with <20% FA in response to EPI. The local population showed a slightly higher aggregation pattern in response to COL, RIS, AA and EPI (excluding non-responders) compared to manufacturer’s reference values. Conclusion: This study has provided a glimpse of the aggregation pattern of the local nationality showing considerable differences in the reference values from manufacturer’s; thus highlighting the need of establishing local reference values.

Effect of aspirin on anti-platelet aggregation function in children with Kawasaki disease / 中国实用儿科杂志

OBJECTIVE: To evaluate the anti-platelet aggregation function of aspirin in children with Kawasaki disease(KD).METHODS: The clinical data of KD patients who was admitted to Capital Institute of Pediatrics-Peking University Teaching Hospital from September 2016 to September 2018 was retrospectively analyzed. All the children were treated with aspirin routinely:high-dose(30-50)mg/（kg·d)in acute stage and low-dose aspirin(3-5)mg/（kg·d)in the recovery period. Then the light transmission aggregometry(LTA)was used to determine the platelet aggregation rate of different doses of aspirin in order to evaluate the anti-platelet aggregation function,and the risk factors of aspirin resistance(AR)were analyzed by statistical method. RESULTS:(1)The platelet aggregation rate(AA%)after treatment with high-dose and low-dose aspirin in children with KD was 30.3%(1.2%,7.1%)and 2.9%(1.5%,60.4%),respectively,and there was no significant difference in platelet inhibition between different doses of aspirin(P=0.174).(2)The incidence of AR was 9.75%(23/236)in the highdose aspirin group and 8.05%(19/236)in the low-dose aspirin group. There was no significant difference in the incidence of AR between the two groups(P=0.617).(3)In the 19 children with AR and 217 children with aspirin sensitivity(AS)in oral low-dose aspirin treatment group,the age,sex,coagulation,biochemistry and other related indexes did not significantly differ between the two groups. CONCLUSION: The antiplatelet aggregation function of aspirin in KD children is not related to the dosage. AR is present in the treatment of Kawasaki disease,and the incidence of aspirin resistance is not related to dosage.

Platelet function tests: A 5-year audit of platelet function tests done for bleeding disorders in a tertiary care center of a developing country

Introduction: The platelet function disorders remain largely undiagnosed or incompletely diagnosed in developing nations due to lack of availability of tests like lumiaggregometry, granule release assay or molecular testing. We performed a retrospective analysis of all the platelet function test (PFT) carried out in past 5 years by Light transmission aggregometery (LTA) using a panel of agonist. The indications and the test results were analyzed by two hematopathologist with the aim to look into the present diagnostic facilities or lack of it for correct diagnosis. This is essential for better management and genetic counselling. Materials and Methods: The PFT was performed both on patients and healthy unrelated age specific controls by light transmission aggregometry on Chronolog platelet aggregometer using platelet rich plasma. The panel of agonists included ADP (10?m/l and 2.0 ?m/l), epinephrine (10.0 ?m/l), collagen (2?g/ml), arachidonic acid (0.75 mM) and ristocetin (1.25 mg/ml & 0.25 mg/l). Results: The 5 years records of 110 cases were audited, 101 of these were tested for clinical bleeding , 35 adults and 66 children. The adults included 29 women and 6 men, 17 to 82 years of age. The children were 16 years to 3 months of age, 30 girls and 36 boys. Platelet function test abnormality was found in 31.6% (32/101) cases ,a majority remained undiagnosed of these about 21% had clinically significant bleeding.The cases diagnosed included Glanzmann Thromboasthenia-11 , von Willebrand Disease-6, Bernard Soulier'syndrome-1, storage pool disorder-6, mild defect of Epinephrine-3, isolated defect with collagen in1. Conclusion: An epidemiologically large proportion of platelet function disorders amongst people living in developing nations remain undiagnosed. This lacunae needs to be highlighted and addressed on larger scale. The options available are to increase the available armamentarium of tests or international collaboration with a specialized laboratory to aid in complete diagnosis.

Monitoring the Antiplatelet Effect of Cilostazol with Light Transmission Aggregometer: Two Cases of Possible Cilostazol Resistance

BACKGROUND: Coronary artery disease is an important cause of death in adults and stent insertion is one of the treatment modalities. The most severe adverse effect of a stent insertion is the formation of a thrombus; therefore, antiplatelet agents are used. The addition of cilostazol to low-dose aspirin and clopidogrel results in a better antiplatelet effect. However, laboratory tests to monitor the effect of cilostazol are insufficient. METHODS: We tested the inhibitory effect of cilostazol using maximal platelet aggregation in 20 healthy volunteers. Conditions for incubation and concentrations of cilostazol and prostaglandin E1 (PGE1) were established and aggregation was induced by 5'-adenosine diphosphate (ADP) and measured with light transmission aggregometry (LTA). Blood samples were incubated with 1 µM and 2 µM cilostazol for 10 minutes at room temperature, and 80 nM PGE1 was added and incubated for an additional 10 minutes. Aggregation was induced by ADP and reactivity was evaluated. RESULTS: The average maximum aggregation (MA) was 58.1% at 1 µM cilostazol and 22.0% when PGE1 was added. The average MA was 42.8% when cilostazol concentration was increased to 2 µM and 21.2% when PGE1 was added. Average inhibition of aggregation at 1 µM cilostazol was not statistically significant (P=0.085), but was significant (P=0.004) at 2 µM cilostazol. Aggregation was not inhibited even with 2 µM cilostazol and PGE1 in 2 volunteers, which suggests possible resistance to cilostazol. CONCLUSIONS: We designed a method to monitor the effect of cilostazol using in vitro incubation with PGE1.

CD62pUsing Light Transmission Aggregometry and Flow Cytometry to Examine the Effect of Clopidogrel / 现代检验医学杂志

Objective To detect clopidogrel effect with light transmission aggregometry (LTA)and flow cytometry (FC). Methods ①Venous blood samples were taken from 71 inpatient with acute corotary syndrome (ACS)in PLA General Hos-pital,including unstable anqina,ST segment elevation myocardial infarction and non ST segment elevation myocardial infarc-tion (46 males,25 females)by random number table from June 2011 to March 2012,whose average age was 69(57~92).②All of them were served 160 mg aspirin and 300 mg clopidogrel after they were in hospital in the beginning,and then served with 75 mg/d clopidogrel for 6 months.On some day,firstly,they were required withdrawing drug for 10 days,and then ve-nous blood samples were separately taken from them before their served-clopidogrel again and their severd-clopidogrel 2 hours later.③The samples were assayed with LTA and FC simultaneously and the platelet aggregation rates before served-clopidogrel (ADPLTA-before serving ),platelet aggregation rates after served-clopidogrel (ADPLTA-after serving ),inhibition rates (ADPLTA-INDU ),PAC-1 activity percentage before served-clopidogrel (PAC-1 before serving ),PAC-1 activity percentage after served-clopidogrel (PAC-1 after serving ),inhibition rates (PAC-1 INHI ),CD62p activity percentage before served-clopidogrel (CD62pbefore serving ),CD62pactivity percentage after served-clopidogrel (CD62pafter serving ),inhibition rates (CD62pINHI )weregotten.All volunteers were signed informed consents and the experiment was approved by the hospital ethics committee.Re-sults ①The paired samples t-test was (t=-2.082,P =0.041)between ADPLTA-before serving (0%~97%)and ADPLTA-after serving (12%~97%),the paired samples t-test was (t = 3.663,P < 0.01)between PAC-1 before serving (15.1% ~ 78.9%)and PAC-1 after serving (14.5% ~ 78.3%);the paired samples t-test was (t = 2.082 and P = 0.041)between CD62pbefore serving (1.5% ~80.8%)and CD62pafter serving (1.4%~41.4%).②The pearson coeffcient correlation results were:ADPLTA-INDU (0%~28.2%) and PAC-1 INHI (0.6%~ 9.1%)(r = 0.297,P = 0.012);ADPLTA-INDU (0% ~ 28.2%)and CD62pINHI (0.1% ~ 48.5%)(r =0.220,P =0.065);PAC-1 INHI (0.6%~9.1%)and CD62pINHI (0.1%~48.5%)(r=0.736,P <0.001).Conclusion Because the correlation was bad between the inhibition rates of clopidogrel detected by FC and them by LTA,FC didn’t apply to clin-ical routine examination of the platelet aggregation.But it could be used to scientific researchs and auxiliary confirmation of routine examination results.

Comparatively Study on the Thromboelastography and Light Transmission Aggregometry in Monitoring Clopidogrel Effect / 现代检验医学杂志

Objective To comparatively study the difference between thromboelastography (TEG)and light transmission ag-gregometry (LTA)in monitoring clopidogrel effect in patients with acute coronary syndrome.Methods 68 patients with a-cute coronary syndrome,who were in hospital from February to December 2013,were enrolled in this study.They received TEG and LTA to determine platelet aggregation.Results Clopidogrel effect was (47.84±26.04)% and (45.64±20.92)%respectively by TEG and LTA.There were negative correlation between LTAADP and TEGADP(r=-0.752,P<0.001),pos-itive correlation between LTAADP and MAADP(r=0.789,P<0.001),negative correlation between TEGADP and MAADP(r=-0.820,P<0.001).Conclusion There was a good correlation between the two methods.TEG can be used to evaluate thera-peutic effect of Clopidogrel effect.