Hemostatic mechanisms

Pathological findings frequently observed in organs of patients who have died of sepsis include disseminated intravascular coagulation (DIC), manifested as diffuse thrombotic occlusions in the entire microvascular system, associated with alterations in the hemostatic mechanism and clinical signs of hemorrhagic diathesis. Many observations indicate that DIC contributes to the major symptoms of the systemic inflammatory response syndrome (SIRS), which frequently complicate sepsis (HI, H2, H3, T6). 

B31. Boermeester, M. A., van Leeuwen, P. A. M Coyle, S. M Wolbink, G. J., Hack, C. E., and Lowry, S. F., Interleukin-1 blockade attenuates mediator release and dysregulation of the hemostatic mechanism during human sepsis. Arch. Surg. 130,739-748 (1995). 

The saliva of the medicinal leech contains a battery of substances that interfere with the hemostatic mechanisms of the host. One of these compounds is hirudin, a potent anticoagulant, which maintains the fluidity of the ingested blood and is the most potent inhibitor of thrombin. Upon binding to thrombin, the cleavage of fibrinogen and subsequent clot formation are prevented. The potency and specificity of hirudin make it a useful antithrombin-III-independent alternative to heparin for the control of thrombosis. 

To understand the evolution of therapy of the acute coronary syndrome (ACS), which includes unstable angina, acute myocardial infarction, and interventional therapy— percutaneous coronary intervention (PCI), it is most useful to trace the historical events that provided a rationale for the use of anticoagulant and antiplatelet drugs, The focus of this chapter is upon the explosion in knowledge of the physiology of the hemostatic mechanism and will trace the rational development of therapy based upon the pathophysiology of the ACS over the past 40 years. 

Thrombus versus embolus A clot that adheres to a vessel wall is called a thrombus, whereas an intravascular clot that floats within the blood is termed an embolus. Thus, a detached thrombus becomes an embolus. Both thrombi and emboli are dangerous, because they may occlude blood vessels and deprive tissues of oxygen and nutrients. Arterial thrombosis most often involves medium-sized vessels rendered thrombogenic by surface lesions of endothelial cells caused by atherosclerosis. In contrast, venous thrombosis is triggered by blood stasis or inappropriate activation of the coagulation cascade, often as a result of a defect in the normal defense hemostatic mechanisms. 

Nicolson, G. L., Irimura, T., Nakajima, M., Updyke, T. V. and Poste, G. (1984). The cellular interactions of tumor cells with special reference to endothelial cells and their basal-lamina like matrix. In Hemostatic Mechanisms and Metastasis (Honn, K. V. and Sloane, B. F., eds.). Martinus Nijhoff, Dordrecht, pp. 295-318. 

Haverback BJ, Dutcher TF, Shore PA, Tomich EG, Terry LL, Brodie BB. Serotonin changes in platelets and brain induced by small daily doses of reserpine lack of effect of depletion of platelet serotonin on hemostatic mechanisms. N Engl J Med 1957 256(8) 343-5. 

Potassium salts are more than 90% absorbed, but blood levels are controlled by hemostatic mechanisms. Climate plays a role in potassium blood levels people in warm climates have 30% more potassium in their blood than people in very cold climates. 

All tissues of the body contain potassium. It is found mainly in the muscle followed by the skeleton. Excretion of potassium via urine is also controlled by hemostatic mechanisms the kidney regulates this so that there is normally no major loss of this essential element. The amount of potassium excreted depends on the chloride ion concentration and the adrenal hormone secretion level. 

Summary - Many diverse novel compounds that inhibit different platelet functions show great promise, not only for potential anti-thrombotic agents, but also for more specific effects on prostaglandin and/or thromboxane A2 synthesis, and serotonin or calcium uptake and release. Many active compounds can be used as tools in the search toward a more complete understanding of the physiologic interactions of the hemostatic mechanisms. This better understanding would lead to the development and use of more potent and selective synthetic compounds in the inhibition of platelet aggregation and fibrin formation, and in the enhancement of fibrinolysis for the control of both arterial and venous thrombosis. It is hoped that some of these new compounds will be evaluated clinically in the near fu ture. 

Other effects. There are many, some probably still unknown. However, effects on the kidneys, bladder, atherosclerosis, hemodynamic and hemostatic mechanisms, the skeletal system, association of malignancies with PG-induced hypercalcemia, other malignancy-related metabolic processes, and even glucose metabolism are being investigated. 

The saliva of the medicinal leech contains a battery of substances that interfere with the hemostatic mechanisms of the host. One of these compounds is himdin, a potent... 

Hemostatic mechanisms and drugs influencing them Hiccup treatment of Hirsutism treatment of... 

Coagulation and hemoagglutination tests showed that the hemostatic mechanism of chitosan seems to be independent of the classical coagulation cascade and appears to be an interaction of the cell membrane of erythrocytes and chitosan. 

Bleeding from injured blood vessels can be arrested by the activation of the hemostatic mechanism [24]. However, an artificial device surface placed in contact with blood can disturb the balance of this mechanism [24]. Excessive blood clotting with increased risk of embolization can occur due to the adhesion of platelets and lenkocytes to device surface and the formation of fibrin network following the... 

Clustering of RBC is a very important and vital biological process (e.g., see [131]), which influences the rheological properties of blood and may lead to severe cardiovascular problems, such as anemia, ischemia, angina, thrombosis, and stroke. Clotting process is accomplished by the solidification of blood. It initiates three separate, but overlapping, hemostatic mechanisms ... 

Fibrinolysis is the final process of the hemostatic mechanism. Like coagulation, fibrinolysis is a complicated interplay between activators and inhibitors. In this process plasminogen is converted to plasmin, the fibrinolytic enzyme that lyses fibrin clot. 

There is potential for aspiration of large quantities of air cansing air embolization with conscious sedation. This problem has been obviated by adequate patient preparation and utilization of sheaths incorporating h ostalic valves and guiding catheters equipped with hemostatic mechanisms. 

Rosenberg RD (1977) Chemistry of the hemostatic mechanism and its relationship to the action of heparin. Fed Proc 36 10-18... 

Changes in the hemostatic mechanism after myocardial infarction. 

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