Epidemiology: Oxidative Stress and Early Atherosclerosis

BACKGROUND:

Low blood antioxidant concentrations are associated with several major degenerative diseases including cardiovascular disease and cancer. Animal, cellular and chemical experiments have elucidated biologic mechanisms consistent with antioxidant protection against several disease processes. Determinants of blood antioxidant concentrations are not well understood in young adults.

The main scientific outcome of this research will be information on distribution and correlates of blood antioxidant concentrations, useful for formulating public health messages concerning maintenance of adequate levels of alpha tocopherol, selenium, ascorbic acid and the carotenoids.

DESIGN NARRATIVE:

An analysis was conducted using serum stored at 70 degrees Celsius, collected in 1985-86 (n=5115) and 1992-93 (n=4086). These analytes were stable in serum samples collected, handled and stored under conditions used in this study. Integrity of the chemical analysis throughout the study was maintained by proven laboratory quality control procedures. Monitoring analyte concentrations in serum from collections seven years apart allowed analysis of age and time dependent changes in serum antioxidants. These data were linked with extensive pre-existing sociodemographic, dietary, other behavioral and physiologic data for the cohort. Statistical analyses provided information on the population's serum antioxidant distribution, tracking, change and major determinants in diverse young adults. In addition, these data established baseline and 7-year change concentration values for followup of this large CARDIA cohort, though the relationship of these serum antioxidants to disease endpoints was not itself part of the work scope. Study of plasma ascorbic acid, which is not stable under our storage conditions, was initiated using fresh samples to be collected in 1995-96 (n=4000).

The Young Adult Longitudinal Study of Antioxidants (YALTA), ancillary to CARDIA study, was renewed in fiscal year 2000 to obtain additional blood and urine samples in the year 15 exam of the CARDIA participants. New measures of circulating lipid, protein, and DNA oxidation products (F2-isoprostanes, advanced glycosylation end-products [AGE], chlorinated and nitrosylated tyrosine, platelet aggregating factor (PAF) acetylhydrolase, paroxonase), urinary DNA damage, soluble intercellular adhesion molecule (ICAM), soluble P-selectin, and relevant genetic polymorphisms. The specific endpoints at the 15 year exam were coronary artery calcification as measured by computed tomography and microalbuminuria.

The study was renewed in 2004 through 2008. Blood and urine was collected from subjects at the CARDIA year 20 exam to remeasure blood F2 isoprostanes, phospholipase A2, superoxide dismutase and carotenoids and tocopherols. Oxidized low density lipoprotein (LDL) and myeloperoxidase was also measured and analysis conducted of the association of antioxidant and oxidative damage levels and the development of subclinical macrovascular disease in this still-young group.

The study renewed for a fourth time in 2010 through 2015, and a renewal application for a fifth renewal period was submitted in summer, 2014. It continues to write reports about different feature of oxidative stress and related phenomena as the CARDIA subjects age.