title: Significantly reduced spontaneous thrombolytic activity in older men: a possible explanation for the gender differences in risk of acute coronary syndromes.
abstract: BACKGROUND
  Although incidence of arterial thrombotic events increases with advancing age, the mechanism of such increased risk is poorly understood. There is also a gender difference; coronary heart disease is more common in men than women. The aim of the present study was to investigate the possible contribution from platelet reactivity and spontaneous thrombolysis, determinants of arterial thrombosis, to the increased risk of thromboembolism in aging, but otherwise healthy subjects.
  
  
  METHODS
  One hundred and forty-five normal subjects (61 men, 82 women) of age between 19 and 77 years were grouped into groups of young (<30 years); middle aged (31-50 years), and older (>51 years), according to their gender and body mass index (BMI). A new in vitro test [Gorog Thrombosis Test (GTT)] was used to measure in sequence both platelet reactivity [occlusion time (OT)] and spontaneous thrombolysis [lysis time (LT)] from one non-anticoagulated blood sample.
  
  
  RESULTS
  OT in all women was 315+/-9.2 s (mean+/-S.E.M.), in all men OT was 300+/-10.6 s. The mean LT in all women was 2557+/-201.5 s, and in all men LT was 2493+/-198.6 s. Advanced age did not enhance platelet reactivity (OT), but increased BMI did (P=0.039). Spontaneous thrombolysis (LT) was impaired in older men but not in women (difference between young vs. middle age: P=0.019; young vs. older: P=0.0002).
  
  
  CONCLUSIONS
  Our findings suggest that in men, spontaneous thrombolytic activity is reduced with age, and this may explain the increased frequency and severity of thromboembolic events. Interestingly, in women, spontaneous thrombolytic activity did not change after menopause.
authors.affiliation: Faculty of Nutrition, Kobe Gakuin University, Kobe, Japan. tsutomu@nutr.kobegakuin.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Yamashita
authors.forename: A
authors.initials: A
authors.lastname: Sato
authors.forename: H
authors.initials: H
authors.lastname: Ikarugi
authors.forename: A
authors.initials: A
authors.lastname: Inoue
authors.forename: K
authors.initials: K
authors.lastname: Kitamori
authors.forename: H
authors.initials: H
authors.lastname: Ishii
authors.forename: J
authors.initials: J
authors.lastname: Yamamoto
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D003327:Coronary Disease / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation; D010979:Platelet Function Tests; D012075:Remission, Spontaneous; D012307:Risk Factors; D012737:Sex Factors; D013927:Thrombosis / Q000453:epidemiology / Q000209:etiology*