Tehran University Medical Journal

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The major Lipoprotein classes are heterogenous. Human serum High-Density-Lipoproteins (HDL) are separated into two major subfractions (HDL2, d=1.063-1.125 g/ml, HDL3, d=1.125-1.210 g/ml) by a simple double precipitation method. There was a strong inverse relation between HDL-Cholesterol (HDL-C) and subfractions HDL2-C and HDL3-C with atherosclerosis. This study demonstrated that HDL-C (P<0.001) and both HDL2-C (P<0.001) and HDL3-C (P<0.01) levels are significantly lower (HDL-C=-35%, HDL2-C=-52%, and HDL3-C=-26%) in the atherosclerosis patients (Coronary-Heart-Disease) than normal subjects. This data supports the proposal that the latter surfation is the major contributor to the anti atherogenic role of serum HDL-C, HDL2-C and HDL3-C.

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Regarding the importance of cardiovascular disease in the health of societies, Hyperlipidemia is considered as an important risk factor. One of the case recently put forward in the fat profile, is high TG (triglycerides) and low HDL-C (High Density Lipoprotein). Nowadays, we believe that TG without the presence of low HDL-C is not considered as a risk factor for cardiovascular disease. So it was decided to perform a descriptive study to define the prevalence of this syndrom, like other risk factors, in urban population of Isfahan. Samples were selected by random sampling method and the sample size, to have reliability of 95%, was about 1200 from the people over 20 year old in 6 age groups and 2 sexes. After inviting the people while going fast (about 14 hours), a questionnaire including perfect identifications was filled and blood factors include total cholesterol, TG, LDL-C (LOW Density Lipoprotein), HDL-C and F.B.S (Fasting Blood Sugar) were measured. Then the statistical analyzing of data was done to define the relation between TG and HDL-C. Regarding the coefficient of correlation and P.value <0.05 in different age and sex groups (except over 70 years old group which was not significant) was defined that TG has an inverse relation to HDL-C and the prevalence in the urban population of Isfahan is 19.7%. Results got from studying the relation between TG serum level and high LDL/HDL fraction (equal or more than five) showed that the more TG gets, the more the fraction is and regarding to its prevalence (11.6%) in Isfahan. It can be a risk factor for cardiovascular disease. So regarding the high prevalence of High TG and low HDL-C syndrome, treating this syndrome can be considered as one of the primary prevention methods. To fufil the latter goal firstly the syndrome must be identified and the related patients must be treated. So the patients with high TG must be tested for HDL-C and LDL-C too. And secondly therapeutic actions to increase HDL-C and to decrease TG level must be done.

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Background: Paraoxonase-1 (PON1) moves with high-density lipoprotein (HDL) particles in blood and prevents low-density lipoprotein (LDL) particles from oxidation. The aims of this study were to investigate the correlation between fatty acid composition of HDL phospholipids with pon-1 polymorphisms and response to lovastatin treatment in people with high blood cholesterol.

Methods: In this descriptive study, 265 patients were selected and divided into two groups based on LDL-C concentrations 131 patients with LDL-C greater than 130 mg/dl (cases) and 134 patients with LDL-C lower than 130 mg/dl (controls). Fatty acids of HDL phospholipids were measured with gas chromatography and lipid profile (cholesterol, triglyceride, LDL-C, HDL-C), apolipoprotein A1 and apolipoprotein B were measured by relevant commercial kits. Oxidized LDL was measured by ELISA method and activity of paraoxonase was determined by a relevant standard manual method. Genotypes of L55M polymorphism were determined by polymerase chain reaction-restriction fragment length polymorphism procedure.

Results: Prevalence of L allele from L55M polymorphism was 0.65 and 0.53 in the case and control groups, respectively (P=0.04). PON1 paraoxonase activity in LL homozygote genotype was higher than other genotypes upon treatment with lovastatin. Concentrations of oleic, linoleic and eicosapentaenoic acids in LL genotype were increased by lovastatin administration.

Conclusion: Allele (L) from L55M polymorphism had a higher frequency in patients with higher LDL-C concentrations. PON1 genotypes seemed to have a modifying role on paraoxonase-1 activity after lovastatin therapy.