The Effect of qat chewing on the level of total homocysteine in patients with and without coronary artery disease

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 1Abdulkafi shujaa, 2Ekram Al-Eryani, 2Munira Dughish

1Department of Internal Medicine ,2Department of Biochemistry Faculty of Medicine and Health Sciences, University of Sana'a – Yemen

Introduction:

Homocysteine is an intermediate sulphur-containing amino acid in one-carbon metabolism, which comprises the folate cycle and methionine pathway, regulates the transfer of carbon groups and related to essential physiological process. These include formation of purines and thymidine for DNA and RNA synthesis, methylation of DNA, RNA, lipids and proteins, and regulation of oxidative stress. Homocysteine is formed in cells from the essential amino acid methionine via methyl transfer reactions, and can be removed from the cell via remethylation to methionine, irreversible trans-sulphuration to cysteine or release of excess intracellular homocysteine into plasma 40. The intracellular concentration of homocysteine is regulated via these processes that require the action of several enzymes and cofactors. Approximately 70% of plasma homocysteine is disulphide bound to proteins. The

remaining 30% is bound to cysteine or homocysteine to form homocysteine-cysteine or homocysteine –homocysteine (or homocysteine).Mixed disulfides, only a very small portion present as unbound free homocysteine. The term total homocysteine (tHcy) refers to the sum of all homocysteine species (uelandetal). Until recently, it was believed that the normal range for homocysteine was 5-15μmol/L. It is now widely accepted that the normal range of (tHcy) may be 10 to 12 μmol/L for middle aged adult and values exceeding this range considered to be a risk factor for cardiovascular disease (Jacobsen, 1998; Christenetal, 2000). In 1969, it was thought that there is a connection between homocysteine and cardiovascular disease, when it was observed in people with a rare hereditary condition, called homocystinuria (the deficiency of one of the three main enzymes in homocysteine metabolism, causes homocysteine to accumulate in the blood and to be

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