title: Plasma oxidizability in Mexican-Americans and non-Hispanic whites.
abstract: Several lines of evidence support an atherogenic role for oxidized low-density lipoprotein (LDL). Previous studies have suggested that although Mexican-Americans have an increased rate of diabetes, obesity, elevated triglyceride levels, and low high-density lipoprotein (HDL) cholesterol levels, their rates of coronary heart disease (CHD) are similar or possibly lower than in non-Hispanic whites. Mexican-Americans have smaller, denser LDL than non-Hispanic whites. On the basis of this latter observation, we postulated that lipid peroxide (LPO) levels would be increased in Mexican-Americans. We examined the oxidizability of plasma in 50 Mexican-Americans and 50 non-Hispanic whites from the San Antonio Heart Study, a population-based study of diabetes and cardiovascular disease, at baseline and after coincubation with a metal-independent system (2'2'-azobis-2-amidinopropane hydrochloride [AAPH]) and a metal-dependent system (Fe2+/H2O2) of oxidation. LPO levels were measured by a modified fluorimetric assay. Vitamin E and plasma fatty acid composition were also determined. We found significantly higher LPO levels at baseline and after AAPH coincubation in Mexican-Americans than in non-Hispanic whites (baseline, 2.75 +/- .09 v 2.07 +/- .09 micromol/L, P < .001; post-AAPH, 5.49 +/- .14 v 5.07 +/-. .04 micromol/L, P = .037). However, no significant ethnic differences were seen after coincubation with Fe2+/H2O2. Diabetes and cigarette-smoking were also associated with higher LPO levels. Mexican-Americans also had lower levels of vitamin E (the predominant lipid-soluble antioxidant in plasma) than non-Hispanic whites, although these differences only partially explained the differences in susceptibility to oxidation. Plasma fatty acids were similar in Mexican-Americans and non-Hispanic whites, suggesting only small differences in diet composition. We conclude that LPO levels are higher in Mexican-Americans than in non-Hispanic whites, and that these results are only partially related to differences in vitamin E levels.
authors.affiliation: Division of Clinical Epidemiology, Department of Medicine, University of Texas Health Science Center, San Antonio, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Haffner
authors.forename: H
authors.initials: H
authors.lastname: Miettinen
authors.forename: M P
authors.initials: MP
authors.lastname: Stern
authors.forename: A
authors.initials: A
authors.lastname: Agil
authors.forename: I
authors.initials: I
authors.lastname: Jialal
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D015227:Lipid Peroxidation; D008054:Lipid Peroxides / Q000097:blood*; D008297:Male; D017058:Mexican Americans; D008875:Middle Aged; D018384:Oxidative Stress; D012307:Risk Factors; D013781:Texas / Q000453:epidemiology; D044465:White People
chemical_list: D000975:Antioxidants; D008054:Lipid Peroxides