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Intimal Thickening and Antioxidants in Hispanics and Anglos (Los Angeles Atherosclerosis Study)

This study has been completed.
Sponsor:
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI)
ClinicalTrials.gov Identifier:
NCT00005372
First received: May 25, 2000
Last updated: June 26, 2005
Last verified: June 2005

May 25, 2000
June 26, 2005
January 1994
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Complete list of historical versions of study NCT00005372 on ClinicalTrials.gov Archive Site
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Intimal Thickening and Antioxidants in Hispanics and Anglos (Los Angeles Atherosclerosis Study)
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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.

Observational
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  • Atherosclerosis
  • Cardiovascular Diseases
  • Heart Diseases
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*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Completed
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February 2005
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No eligibility criteria

Male
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No
Contact information is only displayed when the study is recruiting subjects
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NCT00005372
4264
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National Heart, Lung, and Blood Institute (NHLBI)
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Investigator: James Dwyer University of Southern California
National Heart, Lung, and Blood Institute (NHLBI)
June 2005

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP