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

January 15, 2016 updated by: University of Southern California
To investigate the role of serum and dietary antioxidants, serum pro-oxidants, and smoking on the progression/regression of carotid intima-media thickness (IMT).

Study Overview

Detailed Description

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.

Study Type

Observational

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

No older than 100 years (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Male

Description

No eligibility criteria

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Investigators

  • James Dwyer, University of Southern California

Publications and helpful links

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General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

January 1, 1994

Study Completion

February 1, 2005

Study Registration Dates

First Submitted

May 25, 2000

First Submitted That Met QC Criteria

May 25, 2000

First Posted (Estimate)

May 26, 2000

Study Record Updates

Last Update Posted (Estimate)

January 20, 2016

Last Update Submitted That Met QC Criteria

January 15, 2016

Last Verified

January 1, 2016

More Information

Terms related to this study

Other Study ID Numbers

  • 4264
  • R01HL049910 (U.S. NIH Grant/Contract)

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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