title: Increased platelet aggregation and production of platelet-derived microparticles after surgery for upper gastrointestinal malignancy.
abstract: BACKGROUND
  Since platelet function is known to play a major role in arterial thrombosis, we investigated postsurgery alterations in platelet function that might predispose patients with upper gastrointestinal malignancy to postoperative thrombotic complications.
  
  
  METHODS
  Shear-induced platelet aggregation (SIPA) in platelet-rich plasma was measured in 23 patients who elected to undergo abdominal surgery. Measurement was done by cone-plate viscometer under low shear stress (12 dyn/cm(2)), a physiological condition, and under high shear stress (108 dyn/cm(2)), a pathological condition that simulates in vivo conditions such as those in stenotic arteries. Platelet microparticle (PMP) formation was analyzed by flow cytometry. Plasma von Willebrand factor (vWF) was also measured.
  
  
  RESULTS
  SIPA under high shear stress was significantly enhanced from 44.0 +/- 13.4% preoperatively to 69.5 +/- 15.8% on postoperative day (POD) 1, and it returned to preoperative levels on POD 14. PMP formation under high shear stress was enhanced before surgery (140.8 +/- 38.7%) compared to that under a static condition, and the enhancement was further augmented on POD 1 (219.1 +/- 49.3%). The enhancement of SIPA and PMP formation had no association with disease stage. vWF levels increased significantly on POD 1. Exogenous vWF augmented SIPA and PMP formation under high shear stress, and this augmentation was inhibited by anti-vWF antibody.
  
  
  CONCLUSIONS
  Because PMPs are highly procoagulant, increased SIPA and PMP formation induced by surgical intervention possibly contribute to thrombotic complications. Blockage of platelet interaction with vWF may prevent arterial thrombus formation perioperatively.
authors.affiliation: Department of Surgery and Clinical Oncology, Graduate School of Medicine, Osaka University, Suita, Japan. mikeda@surg2.med.osaka-u.ac.jp
authors.forename: Masataka
authors.initials: M
authors.lastname: Ikeda
authors.forename: Shin ichi
authors.initials: Si
authors.lastname: Iwamoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Imamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Furukawa
authors.forename: Tomio
authors.initials: T
authors.lastname: Kawasaki
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000328:Adult; D000368:Aged; D004837:Epinephrine / Q000097:blood; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000097:blood / Q000556:secondary / Q000601:surgery*; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D010316:Particle Size; D010974:Platelet Aggregation / Q000187:drug effects; D011183:Postoperative Complications / Q000097:blood / Q000503:physiopathology; D013314:Stress, Mechanical; D013927:Thrombosis / Q000097:blood / Q000503:physiopathology*; D015016:Yohimbine / Q000494:pharmacology; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D000317:Adrenergic alpha-Antagonists; D014841:von Willebrand Factor; D015016:Yohimbine; D004837:Epinephrine