A capillary hemostasis mechanism regulated by sympathetic tone and activity via factor VIII or von Willebrand's factor may function as a "capillary gate" and may explain angiodysplasia, angioneurotic edema, and variations in systemic vascular resistance

Vasculopatia livedóide: relato de caso com possível evidência de etiopatogenia neurovascular

A etiopatogênese da vasculopatia livedóide ainda hoje permanece indeterminada e, apesar de algumas etiologias aventadas, com freqüência elas não apresentam associação com a vasculopatia em seu curso. Os tratamentos descritos na literatura não apresentam resultados reproduzíveis. Relata-se caso de paciente de 42 anos, com vasculopatia livedóide e boa resposta ao tratamento pioneiro com a carbamazepina. A droga foi instituída diante das discretas evidências de inflamação, da inconstância dos achados relacionados às teorias sugeridas, da forte sintomatologia dolorosa e dos recentes relatos da participação neural na coagulação, que levaram os autores a considerar a possibilidade de associação vasculoneural na patogênese dessa vasculopatia.

A hypothesis: factor VII governs clot formation, tissue repair and apoptosis

A hypothesis: thrombin is a "Universal Enzyme of Energy Transduction" that employs ATP energy in flowing blood to activate biochemical reactions and cell effects in both hemostasis and tissue repair. All cells possess PAR-1 (thrombin) receptors and are affected by thrombin elevations, and thrombin effects on individual cell types are determined by their unique complement of PAR-1 receptors. Disruption of the vascular endothelium (VE) activates a tissue repair mechanism (TRM) consisting of the VE, tissue factor (TF), and circulating Factors VII, IX and X that governs localized thrombin elevations to activate clot formation and cellular effects that repair tissue damage. The culmination of the repair process occurs with the restoration of the VE followed by declines in thrombin production that causes Apoptosis ("programmed cell death") in wound-healing fibroblasts, which functions as a mechanism to draw wound edges together. The location and magnitude of TRM activity governs the location and magnitude of Factor VIII activity and clot formation, but the large size of Factor VIII prevents it from penetrating the clot formed by its activity, so that its effects are self-limiting. Factors VII, IX and X function primarily as tissue repair enzymes, while Factor VIII and Factor XIII are the only serine protease enzymes in the "Coagulation Cascade" that are exclusively associated with hemostasis.