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Wednesday, October 15, 2003For the current study, Barzilai and his colleagues examined and took blood samples from 213 Ashkenazi Jewish men and women and 216 of their children. The average age of the parents was 98 and almost half were over 100; the range was 95 to 107. The children had an average age of about 68. These groups were compared to a control group. Ashkenazi Jews, who are of Eastern European descent, are remarkably similar in their genetic makeup. This makes them ideal for studies such as this one which seek to find single genetic mutations. As it turned out, the Ashkenazi elders and their offspring were three times more likely than the control groups to have a DNA alteration in the cholesterol ester transfer protein (CETP) gene, which helps regulate blood levels of, and size of, HDL [good cholesterol -ed.] and LDL [bad cholesterol -ed.] molecules. The mutation resulted in lower levels of CETP in the blood, increased levels of HDL and larger HDL and LDL molecules. So, how much bigger are the cholesterol molecules in question? Not much. Although the abstract, the only portion of the study available online without a subscription, says only that they’re “significantly” larger, a closer look at the study reveals the signficance is only in the statistical sense. The mean size of LDL cholesterol particles in the long-lived first generation of Ashkenazi Jews was 21.5 (+/- 0.5) nanometers for women and 21.3 (+/- 0.8) nanometers for men. The control group’s particle size was 21.0 (+/-0.7) nanometers for women and 20.9 (+/- 0.6) nanometers for men - a signifcant overlap in values. The numbers for HDL cholesterol are only a little better. The long-lived first generation had HDL particles that were 9.55 (+/- 0.5) nanometers in women and 9.39 (+/- 0.5) nanometers in men. The control group’s HDL particles were 9.18 (+/- 0.5) nanometers in women and 8.88 (+/- 0.4) nanometers in men. Nanometer differences in particle size no doubt can be significant on the molecular level, but when the mean values overlap so much between the study and the control groups, you have to question the physiological significance of the findings. Where there does appear to be a significant difference, however, is the size of the particles in those with and without disease, at least among the long-lived segment of Ashkenazi. Those who were healthy had a mean HDL particle size of 9.32 (+/- 0.01) nanometers and an LDL of 21.4 (+/- 0.03) nanometers. Those with cardiovascular disease (heart attack or stroke), however, had a mean HDL of 8.96 (+/- 0.03) nanometers and an LDL of 20.8 (+/- 0.05) nanometers. Whether it’s the size of the particles that makes the difference or an interaction between those particles and some other aspect of the subject’s physiological or genetic make-up isn’t at all clear. Similar studies need to be done on the wider population to see if the same correlation exists across ethnic groups before we all run out and have our cholesterol particles measured by nuclear magnetic resonance spectroscopy. One thing for sure, there’s something about those very elderly Ashkenazi that makes them invulnerable to insult: The study participants also seem to be proof of the contention that genes can override the environment. One 103-year-old woman just celebrated 95 years of two-pack-a-day smoking. "We know that we should exercise and diet and not be overweight, but the important thing with those guys was something downstream," Barzilai says. "They could do whatever they wanted." Of 300 elders that Barzilai has interviewed (some after this study was completed), 30 percent were overweight and he can not find a single lifestyle factor that would explain their longevity. The main thing they had in common was parents who had lived a long time. Some people have all the luck, or maybe not. posted by Sydney on 10/15/2003 06:57:00 AM 0 comments 0 Comments: |
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