title: Platelet response to aspirin in Chinese stroke patients is independent of genetic polymorphisms of COX-1 C50T and COX-2 G765C.
abstract: OBJECTIVE
  Aspirin resistance (AR) is common in Chinese stroke patients taking antiplatelet medications; however, few studies have documented the role of cyclooxygenase (COX)-1 C50T and COX-2 G765C polymorphisms in AR. The aim of this study was to investigate the prevalence of AR in Chinese stroke patients and the relationships between AR and COX-1 C50T and COX-2 G765C polymorphisms, and to evaluate the effect of these polymorphisms on platelet response to aspirin.
  
  
  METHODS
  We prospectively enrolled 634 Chinese stroke patients. Platelet aggregation testing was performed before and after aspirin administration. The pre- and post-aspirin levels of 11-dehydrothromboxane B(2) (11-dTxB(2)) were determined in urine samples. COX-1 C50T and COX-2 G765C genotypes were determined by a polymerase chain reaction-allelic restriction assay.
  
  
  RESULTS
  AR was detected in 129 patients (20.4%), aspirin semi-resistance (ASR) was detected in 28 patients (4.4%), and aspirin sensitivity (AS) was detected in 477 patients (75.2%). There was no association between COX-1 C50T or COX-2 G765C polymorphisms and ASR+AR. Aspirin could efficiently reduce 11-dTxB(2) production by approximately 75%. In addition, platelet aggregation, both in response to arachidonic acid (AA) and adenosine 5'-diphosphate (ADP), was inhibited by more than 80% and 40%, respectively; however, the percentage reduction in platelet aggregation and 11-dTxB(2) levels was not significantly different between the COX-1 C50T and COX-2 G765C genotypes (p＞0.05).
  
  
  CONCLUSIONS
  There was no association between COX-1 C50T and COX-2 G765C polymorphisms and AR in Chinese stroke patients. In addition, COX-1 C50T and COX-2 G765C polymorphisms had no effect on the platelet response to aspirin.
authors.affiliation: Department of Neurology, 3rd Affiliated Hospital of Wenzhou Medical College, Wenzhou, China. yxy6406@yahoo.com.cn
authors.forename: Xingyang
authors.initials: X
authors.lastname: Yi
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhou
authors.forename: Jing
authors.initials: J
authors.lastname: Lin
authors.forename: Lifen
authors.initials: L
authors.lastname: Chi
authors.forename: Zhao
authors.initials: Z
authors.lastname: Han
mesh_terms: D000368:Aged; D001241:Aspirin / Q000494:pharmacology*; D001483:Base Sequence; D001792:Blood Platelets / Q000187:drug effects*; D002681:China; D051545:Cyclooxygenase 1 / Q000235:genetics*; D051546:Cyclooxygenase 2 / Q000235:genetics*; D017931:DNA Primers; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D020521:Stroke / Q000097:blood* / Q000201:enzymology / Q000235:genetics; D013929:Thromboxane B2 / Q000031:analogs & derivatives / Q000652:urine
chemical_list: D017931:DNA Primers; D013929:Thromboxane B2; C049235:11-dehydro-thromboxane B2; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D001241:Aspirin