Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thrombus formation depends on adherence of blood-formed elements to the intimal surface through platelet-vessel surface interaction, platelet release phenomena and aggregation, formation of fibrin, and the enmeshing of blood cells. Arterial thrombi involve platelet aggregation, whereas venous thrombi found in low flow or during stasis have greater proportions of erythrocytes and fibrin. It is not known if or how abnormalities of flow resistance, platelet thrombus formation, or endothelial and dynamic parameters affect the microcirculation, largely due to the difficulty of obtaining comprehensive data from these systems. Increases of fibrinogen observed in many disorders may result in minor changes in blood viscosity without known physiologic consequence, but in most disorders in which thrombosis is observed, the pathophysiologic mechanisms are multifactorial and abnormal blood viscosity is presumed to be a significant but not limiting component. Therapeutic approaches in thrombotic disorders should recognize which elements of the thrombotic triad predominate. In arterial disorders focus should be on platelet activity, and the objectives of venous thrombosis treatment include prevention of morbidity and death from pulmonary embolism, reduction of morbidity resulting from the acute thrombotic episode, and prevention of the postphlebitic syndrome. Pathology, mechanism, and treatment for specific thrombogenic disorders are described. Treatments suggested for hyperviscosity involve giving antibiotics during crises. Also discussed are thalassemia, paroxysomal nocturnal hemoglobinuria, polycythemia, cryoglobulinemia, paraproteinemia, diabetes mellitus, and disseminated intravascular coagulation. Studies have established a relationship between thromboembolic disease and oral contraceptives (OCs). The risk is only increased while the patient is taking OCs but is compounded in women undergoing surgery or who have a disorder which predisposes to venous disease. The risk for myocardial infarction or stroke is significantly increased when OCs are taken over age 35 and when there is hypertension, smoking, type-II hyperlipoproteinemia, and diabetes mellitus. The risk appears to be a function of estrogen dosage, causing a 25% mean increase in calf venous volume and 30% decrease in vein velocity of venous blood compared to controls. Low flow rates may contribute to venous thromboembolism. OCs may alter precisely regulated systems of coagulation and fibrinolysis and recent studies confirm abnormalities in the hemostatic system attributed to OCs. 16% of women taking OCs have a 60% or greater reduction in antithrombin III activity. The multiple effects of OCs often result in low-grade activation of the hemostatic system, potentially lowering the threshold to precipitate thrombus formation and possibly explaining the increased incidence of thromboembolic disease. Heparin appears to reverse many of these problems.
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PMID:Blood viscosity and thrombosis: clinical considerations. 676 12

The non-healing leg ulcer is examined by discussing three disease processes: peripheral vascular occlusive disease (PVOD), chronic venous insufficiency (CVI), and vasculitis. For PVOD, management decisions are based on risk factors and disease history. Comprehensive management includes the discontinuation of smoking, exercise conditioning and regulation of diabetes, hyperlipidemia, hypertension, and the appropriate application of anticoagulant/antiplatelet drugs. Methods of surgical management include bypass with autogenous or synthetic material in addition to reconstructive surgery with patch angioplasty or extra-anatomic bypass, amputation, percutaneous transluminal angioplasty/stents, thrombolytic infusion, atherectomy, intraluminal ultrasound, and angioscopy. The optimal healing environment for all ulcers prevents contamination, pain, and fluid loss. In CVI, higher venous pressure in the veins of the lower limb during exercise results in ambulatory venous hypertension and ulceration. Various theories are associated with the disease and ulceration process; the classic treatment of elevation, ambulation, and compression for venous disease remains unchallenged. Diagnosis is based on history, physical examination, invasive venography, and/or non-invasive studies. Two groups of vasculitic disorders that share varying degrees of vascular inflammation and necrosis are arteritis (lupus, erythematosus, periarteritis nodosa, dermatomyositis) and blood dyscrasias (sickle cell disease, thalassemia). Leg ulcers associated with vasculitis are due to inadequate tissue oxygenation at the local level, are typically chronic, slow to heal, and commonly recur.
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PMID:The non-healing leg ulcer: peripheral vascular disease, chronic venous insufficiency, and ischemic vasculitis. 939 80