title: Decrease in microvesicle-associated tissue factor activity in morbidly obese patients after bariatric surgery.
abstract: Tissue factor (TF) is the main in vivo initiator of the blood coagulation cascade. Active circulating TF was detected on small, negatively charged membrane vesicles, the so-called microvesicles (MVs), which are released upon cell activation and apoptosis from a variety of cells. Increased coagulation activation was found in morbidly obese patients, and elevated levels of TF-bearing MVs may contribute to the prothrombotic state in these patients.
  
  
  
  To determine MV-associated TF activity levels in morbidly obese patients before and after weight loss due to bariatric surgery.
  
  
  
  MV-TF activity was measured with a factor Xa generation assay in morbidly obese patients before and 2 years after bariatric surgery. In addition, clinical parameters were determined.
  
  
  
  Seventy-four morbidly obese patients (mean age: 42 (±11) years; 61 females) were included in this study. After bariatric surgery, the body mass index decreased from (median, 25-75th percentile) 45.5 (42.3-50.2) to 30.5 (28.0-34.4 kg m(-2); P<0.001), and a significant improvement in metabolic parameters was observed. Preoperative MV-TF activity correlated with C-reactive protein levels (r=0.3; P=0.02). Postoperatively, the mean MV-TF activity decreased significantly from 0.20 pg ml(-1) (0.18-0.47) to 0.02 (0.00-0.28; P<0.01).
  
  
  
  We could demonstrate a significant decrease in MV-TF activity after weight loss in morbidly obese patients. Decreased MV-TF activity might contribute to an improved coagulation profile in these patients after weight loss.
authors.affiliation: Department of Internal Medicine I, Rudolfstiftung Hospital Vienna, Vienna, Austria.
authors.forename: L
authors.initials: L
authors.lastname: Ay
authors.affiliation: Clinical Division of Haematology and Haemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Thaler
authors.affiliation: Department of Internal Medicine I, Rudolfstiftung Hospital Vienna, Vienna, Austria.
authors.forename: J-M
authors.initials: JM
authors.lastname: Brix
authors.affiliation: Division of Angiology, Department of Medicine II, Medical University of Vienna, Vienna, Austria.
authors.forename: G H
authors.initials: GH
authors.lastname: Schernthaner
authors.affiliation: Clinical Division of Haematology and Haemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Ay
authors.affiliation: Clinical Division of Haematology and Haemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria.
authors.forename: I
authors.initials: I
authors.lastname: Pabinger
authors.affiliation: Department of Internal Medicine I, Rudolfstiftung Hospital Vienna, Vienna, Austria.
authors.forename: G
authors.initials: G
authors.lastname: Schernthaner
mesh_terms: D000328:Adult; D001317:Austria / Q000453:epidemiology; D050110:Bariatric Surgery; D015415:Biomarkers / Q000378:metabolism; D001777:Blood Coagulation / Q000502:physiology; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000378:metabolism / Q000517:prevention & control; D015536:Down-Regulation; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000150:complications / Q000378:metabolism* / Q000601:surgery*; D011184:Postoperative Period; D011446:Prospective Studies; D013925:Thromboplastin / Q000378:metabolism*; D016896:Treatment Outcome; D015431:Weight Loss
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein; D013925:Thromboplastin