Intimal Thickening and Antioxidants in Hispanics and Anglos (Los Angeles Atherosclerosis Study)
Intimal Thickening and Antioxidants in Hispanics and Anglos (Los Angeles Atherosclerosis Study)
To investigate the role of serum and dietary antioxidants, serum pro-oxidants, and smoking on
 the progression/regression of carotid intima-media thickness (IMT).
BACKGROUND:

 A finding from the Cholesterol Lowering Atherosclerosis Study (CLAS), a clinical trial,
 indicated that common carotid intima-media thickness responded more rapidly and more markedly
 to LDL-C lowering treatment than angiographic coronary stenosis or carotid roughness. New
 data from a primate model also showed ultrasound detection of intimal thickening in response
 to a hypercholesterolemic diet within twelve months. These findings suggest that carotid IMT
 is a reliable and rapidly responding marker of extent of atherosclerosis. However, less than
 a third of the observed therapeutic benefit on carotid IMT found in CLAS was explained by
 change in LDL-C and HDL-C, suggesting that related (or other) factors are more directly
 linked to atherogenic mechanisms. In addition, a Finnish epidemiologic study found that LDL-C
 was predicative of rate of progression in carotid IMT only in persons with high serum levels
 of (pro-oxidant) copper. . These and other data support a model of atherosclerosis in which
 intracellular accumulation of modified LDL is promoted/retarded by serum
 pro-oxidants/antioxidants.

 DESIGN NARRATIVE:

 The study tested the specific hypotheses that the positive association between rate of
 increase in carotid IMT and low density lipoprotein cholesterol (beta deltaIMT/LDL) was
 greater in persons with [1] higher levels of serum pro-oxidants (relative to persons with
 lower levels of serum pro-oxidants), [2] lower levels of serum antioxidants, [3] lower levels
 of dietary antioxidants; and [4] that regression of carotid IMT associated with smoking
 cessation would be detected in 30 months. Hypothesis were tested with the longitudinal
 observation of carotid IMT in Hispanic and non-Hispanic white women and men. The inclusion of
 Hispanics and women was motivated by their prevalence in the study population (18 percent
 Hispanic, 40 percent women), and by the then recent report that incidence of hospitalization
 for myocardial infarction was elevated in Hispanics. Seventy three persons from each of four
 ethnicity-sex groups aged 40-60 years (n-292), and 83 smokers and recent quitters (n-166)
 were recruited from employees in an ongoing study. Baseline blood, diet and potential
 confounder variables were related to 18 and 36 month (6, 12, 18, 24 and 30 month in smoker(s)
 changes in carotid IMT. Levels of antioxidant vitamins, including alpha-tocopherol,
 ascorbate, and beta carotene, in the plasma were measured at baseline. Plasma levels of
 negatively charged LDL were measured in a sub-sample of subjects with the most rapidly
 progressing common carotid intima-media thickness and in an age-sex matched subsample with
 the least rapidly progressing common carotid intima-media thickness. Finally, an ultrasound
 measurement of carotid arterial stiffness, another indicator of early atherosclerosis, was
 developed to address the role of blood pressure.

 The Los Angeles Atherosclerosis Study (LAAS) has been renewed through February, 2004 to
 continue follow-up of the cohort for a total of seven years with two additional measures of
 arterial dysfunction, including endothelial function of the brachial artery and
 distensibility or stiffness of the common carotid artery.
No eligibility criteria