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Cerebral vasospasm following subarachnoid hemorrhage has high morbidity and mortality. Mathematical modeling of the progression of the condition provides insight to improve clinical treatment of patients post subarachnoid hemorrhage. An existing model of the clotting cascade is expanded to include the theoretical conditions of cerebral vasospasm. We consider clotting factor XIIIa, which has been implicated as a primary cause of the entrenchment of the smaller diameter. Solutions for clotting are used as boundary conditions to solve the concentration of diffusible clotting factors in the vessel wall and cerebrospinal fluid (CSF). Each domain (clot, vessel wall, CSF) is described by a separate initial-boundary value problem, requiring unique conditions, reaction-diffusion equations, and diffusion coefficients. Additionally, the results from the first domain (the clot) provide a subset of the boundary conditions for the second and third domains (arterial wall and CSF, respectively). Although this approach captures many detailed components of the clotting process, a simpler method for investigating the formation and dissolution of a clot post subarachnoid hemorrhage is to neglect the bulk of the clot cascade to focus on the most salient features, namely, the formation of cross-linked fibrin and the degradation of fibrin by plasmin. By assuming first order kinetics in the initial hours following hemorrhage, we find a simplified expression with kinetic rates that may be adjusted depending on experimental conditions.

Patients with rheumatoid arthritis (RA) have a shorter life span than the general population. An increased death due to cardiovascular disease (CVD) has been reported. RA is characterized by synovitis and joint destruction accompanied by an acute phase reaction and systemic features. The present work investigates the epidemiology of CVD in patients with RA in the county of Västerbotten and the influence of inflammation on lipid metabolism and haemostasis. In a retrospective cohort study on 606 RA patients, the overall mortality was significantly higher than in the general population, with an excess death rate for CVD and for ishemic heart diseae (IHD) in both sexes. Multiple Cox regression, showed that male sex, higher age at disease onset and cardiovascular event increased the risk for death. Male sex, high age at disease onset and hypertension increased the risk for cardiovascular event. Diabetes mellitus, treatment with corticosteroids, disease modifying antirheumatic drugs and postmenopausal estrogen neither influenced survival nor the risk of cardiovascular event. In 93 patients with active RA, the levels of cholesterol, high density- (HDL) and low density (LDL) lipoprotein cholesterol were significantly lower, and Lipoprotein(a) was significantly higher compared to controls. In a follow-up on 53 patients, a relation between the change of Lp(a) and acute phase proteins was found only in patients with high levels of Lp(a). Preheparin lipoprotein lipase (LPL) activity and mass were significantly decreased in 17 postmenopausal women with active RA. Preheparin LPL mass correlated inversely to several acute phase proteins and interleukin-6. Low levels of LPL mass may implicate increased hepatic clearence but also increased macrophage ingestion of lipoproteins via the LDL receptor-related protein (LRP). Haemostasis of the circulation was investigated in 74 of the 93 patients with active RA. In patients with extraarticular disease, the release of tissue plasminogen activator (tPA) was significantly decreased, and its inhibitor (PAI-1) was significantly increased compared to patients with nonsystemic disease, implicating hypofibrinolysis. In a two year follow-up, patients with thromboembolic events had significantly elevated levels of von Willebrand factor, PAI-1, triglycerides and haptoglobin compared to event-free patients. In 29 RA patients and 18 spondylarthropathy patients with gonarthritis, radiological joint destruction correlated to PAI-1 antigen in synovial fluid and, inversely, to plasminogen. A relationship between activation of fibrin degrading proteolytic enzymes and joint destruction was implicated. In conclusion, several processes involved in lipid metabolism and haemostasis are influenced in active RA. In view of the increased death rate due to CVD, an efficient control of inflammation should be important, not only for reducing joint destruction, but also for reducing systemical atherogenic and thrombogenic effects. / <p>s. 1-54: sammanfattning, s. 55-133: 6 uppsatser</p> / digitalisering@umu.se