Document Details
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Document Type |
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Article In Conference |
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Document Title |
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Serum Total Homocysteine Concentrations in Normal and Cardiovascular Disease Patients معدلات تركيز الهوموسيستسن الكلي في مصل الدم في الاصحاء ومرضى ضغظ الدم |
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Subject |
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medicine, dentistry and pharmacological sciences |
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Document Language |
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Arabic |
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Abstract |
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Homocysteine is a sulpher-containing amino acid that is closely
related to methionine and cysteine. All homocysteine found in organisms is
formed in the metabolism of the essential amino acid, methionine, in the
methylation cycle. This is the only known source of homocysteine. Reduced
homocysteine is in a highly reactive free thiol group, which is susceptible to
auto-oxidation at physiological pH, thereby forming disulphide bonds between
two molecules or mixed disulphides with other thiols.
In plasma only about 1% of homocysteine exists in a free reduced
form. About 70% is bound to alb.umin and the rest forms low molecular weight
disulphides, predominately with cysteine. The sum of all the forms is termed
total homocysteine. The assays generally measure the total homocysteine in
plasma or serum, sometimes in cerebrospinal fluid, rarely in urine.
Three enzymes are directly involved in the homocysteine
metabolism: methionine synthase, betaine homocysteine methyl transferase,
and cystathionine D-synthase.
Vitamins 86, 812 , and folate are cofactors to these enzymes. If the
metabolism is disturbed, because of some enzymatic defect or intracellular
deficiency of some cofactors to the mentioned enzymes, homocysteine
At
accumulates in the cell and is then transported to the circulation where its
level rises.
Homocysteine is mainly eliminated by renal catabolism. Only about
1% of the homocysteine filtered by the glomeruli is normally found in the urine
[Guttormsen, et aI., 1997]. The rest is reabsorbed and metabolized. Thus, the
kidneys are homocysteine metabolizing rather than homocysteine-excreting
[Van-guldener, et aI., 1998, and Refsum, 1998].
Homocysteine is metabolized through two major pathways:
transsulphuration and methylation. Normally about 50% is catabolised in the
transsulphuration pathway, where homocysteine and serine for cystathionine,
which is cleared into. cysteine and a-ketobutyrae. The other 50% enter the
methylation cycle, which is part of the one-carbon metabolism. Sadenosylmethionine
is an important regulator of the remethylation and
transsulphuration of homocysteine.
Cardiovascular diseases (CVD) are one of the most important health
problems and remain to be the major cause of death and disability in many
countries, all over the world. Atherosclerosis and thrombosiS are the two
etiological causes of coronary heart disease (CHD). Atherosclerosis is
principally a disease of the large arteries in which lipid deposits called
atheromatous plaques in the subintimal layer of the arteries. These plaques
contain especially large amounts of cholesterol. Obesity, smoking, diabetes,
hypertension and abnormal plasma lipid levels are recognized risk factors that
contribute to the development of CHD [Rifai, 1986 and Ramirez, et aI., 1992].
This theory hold that cholesterol, mainly its oxidized low density lipoprotein
Ao
(LDL) variety, collects in plaques that line the insides of large and small
arteries.
The aim of these projects is to measure total homocysteine in normal
individual and coronary heart disease patients to fired ant if there is any
relationship between homocysteine and CHD. |
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Conference Name |
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the second annual meeting for scientific research |
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Duration |
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From : 27 محرم AH - To : 28 محرم AH
From : 30 مارس AD - To : 31 مارس AD |
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Publishing Year |
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1424 AH
2003 AD |
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Number Of Pages |
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7 |
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Article Type |
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Article |
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Added Date |
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Tuesday, January 13, 2009 |
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Researchers
| سمير محمد خوجة | Khoja, N/A N/A | Investigator | | |
| زهير مرزوقي | Marzouki, N/A | Researcher | | |
| خالد مرزوقي | Marzouki, N/A | Researcher | | |
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