Rex L. Jamison

Research/Lab website:   Description of research

1. The Dept. of Veterans Affairs Cooperative Studies Program, "Homocysteinemia in Kidney Disease and End Stage Renal Disease", or "The Homocysteine Study" (HOST), for short, was a prospective, randomized, two-arm, double blind, placebo-controlled clinical trial in patients with advanced chronic kidney disease. Its aim was to determine if large doses of folic acid, vitamins B6 and B12, to lower plasma homocysteine levels, would reduce the mortality (primary endpoint) of patients with advanced chronic kidney disease or end stage kidney disease. Secondary endpoints included symptomatic myocardial infarction, disabling stroke, and amputation of all or part of a leg, a composite of the primary and foregoing secondary endpoints, and in hemodialysis patients, thrombosis of the vascular access. Thirty-six medical centers participated; 2,056 patients were enrolled. The duration of the study was 6 years. The results showed no difference in the number of deaths or cardiovascular events between the treatment and the placebo groups. These findings do not support the widespread use of supplemental vitamins in patients with kidney disease to improve survival or reduce cardiovascular disease.

2. A substudy of HOST, "Genetic Tissue Banking for the HOST Trial", involved the collection and storage of DNA from blood samples taken from HOST subjects. The intent is to determine whether polymorphisms of candidate genes in patients with advanced chronic kidney disease puts them at increased risk for cardiovascular morbidity and mortality or interferes with treatment to lower plasma homocysteine levels.

3. A second substudy of HOST, sponsored by the NIH, "Kidney Disease, Hyperhomocysteinemia and Cognitive Function" has been completed. The purpose was to see if vitamin treatment lowered the risk or slowed the progression of cognitive impairment in patients with chronic kidney disease. The results are pending.

4. I have long standing interest in the urinary concentration mechanism, particularly the countercurrent hypothesis of the loops of Henle and the countercurrent exchange role played by the capillaries of the renal medulla (the vasa recta).