title: Platelet hyperactivity and fibrin clot structure in transient ischemic attack individuals in the presence of metabolic syndrome: a microscopy and thromboelastography study.
abstract: BACKGROUND
  Strokes are commonly preceded by transient ischemic attacks (TIAs). TIA is often associated with metabolic syndrome (causing chronic inflammation), resulting in a proinflammatory- and procoagulant-environment. The aim of this study was to determine whether platelet- and fibrin network-morphology or coagulation profiles of individuals that suffered a TIA in the presence of metabolic syndrome was altered when compared to healthy individuals.
  
  
  METHODS
  The study consisted of 40 voluntary participants. Twenty individuals that suffered a TIA in the previous 48 h with at least two metabolic syndrome risk factors present and twenty healthy age-matched controls. Scanning electron- and atomic force microscopy was used to study platelet- and fibrin-morphology, atomic force microscopy was used to study platelet- and fibrin fiber-elasticity and thromboelastography for the study of coagulation profiles. Statistical analysis was performed to compare the two groups. In all cases a p-value of less than 0.05 was considered statistically significant.
  
  
  RESULTS
  Platelets of the control group appeared spherical with few pseudopodia present while the platelets of the TIA individuals presented with numerous pseudopodia and spreading, indicating activation. Platelet aggregation was also present. The fibrin networks of the healthy individuals consist of thick and thin fibers that form an organized network of fibers. The fibrin networks of the TIA individuals appeared less organized with less taut fibers. Fibrin fiber thickness was found to be significantly increased in the TIA group (p-value <0.001) when compared to healthy controls. The thicker fibers formed irregular networks with thick masses of fibrin fibers. Platelet and fibrin fiber elasticity was found to be significantly lower in the experimental group (p-value 0.0042 and p-value 0.0007 respectively). The hemostatic profiles of the diseased individuals did not differ significantly (p-value > 0.05) from the healthy controls, indicating a normal functioning coagulation cascade.
  
  
  CONCLUSIONS
  The findings indicate that pathological clot formation is not caused by alterations in the coagulation cascade but rather by the premature activation of platelets (as a result of chronic inflammation) that in turn causes altered fibrin formation.
authors.affiliation: Department of Physiology, Faculty of Health Sciences, University of Pretoria, Private Bag x323, Arcadia, 0007, South Africa.
authors.forename: Mia-Jeanne
authors.initials: MJ
authors.lastname: van Rooy
authors.affiliation: Department of Neurology, Faculty of Health Sciences, University of Pretoria, Arcadia, 0007, South Africa.
authors.forename: Wiebren
authors.initials: W
authors.lastname: Duim
authors.affiliation: Department of Statistics, Faculty of Natural Sciences, University of Pretoria, Arcadia, 0007, South Africa.
authors.forename: Rene
authors.initials: R
authors.lastname: Ehlers
authors.affiliation: Unit of Microscopy and Microanalysis, Faculty of Natural Sciences, Arcadia, 0007, South Africa.
authors.forename: Antoinette V
authors.initials: AV
authors.lastname: Buys
authors.affiliation: Department of Physiology, Faculty of Health Sciences, University of Pretoria, Private Bag x323, Arcadia, 0007, South Africa. resia.pretorius@up.ac.za.
authors.forename: Etheresia
authors.initials: E
authors.lastname: Pretorius
mesh_terms: D000328:Adult; D000368:Aged; D001777:Blood Coagulation; D001792:Blood Platelets / Q000378:metabolism* / Q000648:ultrastructure; D016022:Case-Control Studies; D004548:Elasticity; D005260:Female; D005337:Fibrin / Q000378:metabolism* / Q000648:ultrastructure; D005342:Fibrinolysis; D006801:Humans; D002546:Ischemic Attack, Transient / Q000097:blood* / Q000150:complications / Q000175:diagnosis; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood* / Q000150:complications / Q000175:diagnosis; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D015539:Platelet Activation; D010974:Platelet Aggregation; D011237:Predictive Value of Tests; D012307:Risk Factors; D013916:Thrombelastography
chemical_list: D005337:Fibrin