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Showing posts from February, 2020

Malaria

Malaria Malaria Malaria affects 100 million people and kills 1.5million every year. The etiologic agent is a protozoa called plasmodium and the anopheles mosquito acts as a vector. The massive antimalaria campaign from 1950 to 1980 failed and produced resistant mosquito for DDT and resistant plasmodium to chloroquine. Life cycle and pathogenesis The sporozoites transmitted by the mosquito bites pass into the blood stream and invade the hepatocytes by binding hepatocyte receptors for serum proteins thrombospondin and properdin. this occurs because the sporozoites have similar domains to these proteins. Within the liver cell they multiply rapidly and as many as 30,000 merozoites (asexual haploid blood form) are released into the blood when hepatocyte ruptures. ·        The HLA-B53 associated resistance to PF. Infection showed by many Africans appears caused by the ability of HLA-B53 to present liver stage malaria Ag to cytotoxic T...

AUTOIMMUNE DISEASES

AUTOIMMUNE DISEASES · Diseases caused by immune reaction to self Ag. · The presence of auto reactive Ab or T cells does not equate to autoimmune disease. Sometimes these Ab are present in otherwise health individual. In many disease attributed to autoimmunity, there is no absolute proof. Immunologic tolerance. · Is a state in which an individual is incapable of developing an immune response against specific Ag. · Self tolerance specifically refers to a lack of immune response to his own tissue Ag. There are 2 mechanisms that explain this tolerance. 1. Central tolerance. · Is the deletion of the auto reactive T and B cells during their maturation in the central lymphoid organs (thymus and bone marrow) · Many self Ag are processed and presented to the developing T and B cells by thymus and marrow APC cells in association with self MHC. Any T or B cell that expresses a receptor for such self Ag is deleted by apoptosis. This results in peripheral T ...

Shock

Shock ¨ Shock is a cardiovascular collapse and is defined as: systemic hypotension owing to reduction either in cardiac output or in effective circulating blood volume. ¨ It is the consequence of a number of potentially lethal clinical events e.g. severe hemorrhage, extensive trauma or burns, large myocardial infract, massive lung embolism and sepsis. ¨ It is the end result of hypotension followed by tissue hypo perfusion and cellular hypoxia. ¨ Although the hypoxia and the metabolic effects cause, initially, reversible cell injury, persistence of the shock causes irreversible cell injury and can culminate in the death of the individual. Shock can be classified into 3 general categories: 1. Cardiac: results from heart pump failure cause by intrinsic myocardial damage, ventricular arrhythmias, cardiac tamponate or outflow obstruction (e.g. lung embolism) 2. Hypovolumoic: results from hemorrhage or fluid loss e.g. trauma, burns. 3. Septic : systemic microbia...
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