Mechanisms of Low Levels of Apolipoprotein B
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|ClinicalTrials.gov Identifier: NCT00005565|
Recruitment Status : Completed
First Posted : May 26, 2000
Last Update Posted : July 29, 2016
|Condition or disease|
|Cardiovascular Diseases Heart Diseases Hypobetalipoproteinemia|
Elevated apoB levels are associated with an increased risk of coronary heart disease. Hypobetalipoproteinemia (HBLP) is characterized by apoB levels less than the 5 percentile. Dr. Welty, the principal investigator, sequenced mutations for truncated forms of apoB-67, apoB-55 and apoB-44.4 which causes HBLP, described a kindred from the Framingham Heart Study with HBLP due to an unidentified apoB gene mutation and purified apoB-67 containing lipoprotein particles. Heterozygous apoB-67 subjects have one normal allele making apoB-100; therefore, apoB levels would be predicted to be at least 50 percent of normal; however, they are 24 percent of normal. Dr. Welty has shown that these lower than expected levels result from decreased production of VLDL apoB-100, LDL apoB-100 and apoB-67, increased catabolism of VLDL apoB-100, and increased direct removal of apoB-67 from VLDL.
The first aim is to locate the apoB gene mutation in the Framingham kindred. The second aim is to perform stable isotope studies in the apoB-55 and apoB-44.4 kindreds to determine if apoB metabolism for these shorter truncations is similar to that for apoB-67. In aim three, apoB-100 synthesis is studied in heterozygous apoB-70 transgenic mice. If it is 25-25 percent of normal litter mates, the mechanism for this reduction in apoB-100 levels will be studied in hepatocytes isolated from the transgenic mice. In specific aim 4, size and composition of VLDL are compared in apoB-67 subjects and controls to determine if larger size or compositional changes account for the faster catabolism of VLDL apoB-100. The study has been extended through June 2007.
|Study Type :||Observational|
|Study Start Date :||August 1997|
|Actual Primary Completion Date :||June 2002|
|Actual Study Completion Date :||June 2002|
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Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00005565
|OverallOfficial:||Francine Welty||Beth Israel Deaconess Medical Center|