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|Subject: cholesterol act two||Date: 1/21/2005 11:58 AM|
|Author: emiller8988||Number: 35779 of 46904|
Well, we've met the three stooges LDL delivery truck. LDL levels are a critical risk factor for CV disease and the lower it goes (the more we get those idiots off the road) the lower CV risk goes. Little children have LDL levels in the 20-30 range. So far so good. Rising HDL levels are associated with decreasing risk... go get 'em Dudly Do-Right!
BUT! back to Framingham and those poor poor pin-cushion people. Over 1/3 of all heart attacks and strokes occur in apparently healthy folks with completely normal cholesterol levels. Enter rust! oxidation!... come hither inflammation. You see, when the little giblet of cholesterol gets dropped (so to speak) remember it tries to bury itself in the wall of the blood vessel. That process creates inflammation. It's the combination of cholesterol AND inflammation that cause trouble.
There are a number of molecular markers of inflammation that sit at the critical interface between the blood flow and the vascular endothelial cells. Those endothelial cells are a very active organ, intensely involved in the management of the disease. They're involved in the transmission of the cell adhesion molecules across that border. They're critically involved in the tethering and adhesion of the monocytes and the macrophages; attachment through the variety of adhesion molecules (E-selectin, P-selectin, vascular cell adhesion molecule [VCAM] and the like); migration of these cells into the intimal space; and inside that milieu with oxidized LDL, the conversion of these into lipid-laden macrophages and the development of the atherosclerotic plaque.
HA! just kidding, sort of... I just wanted to let everyone know I can say those big words too! Ok OK enough showing off, back to the story...
The process of inflammation and oxidation result in something similar to rust... it's a sort of wearing out process. Lo and behold, there appears to be a marker for this rust process... a blood test called HIGH SENSITIVITY C-REACTIVE PROTEIN (HS-CRP).
Back in 1997, it doesn't seem like that long ago, a study was published of doctors and their health. In the Physician's Health Study, they were trying to understand why individuals were having heart attacks in the absence of major clusters of risk factors. They were able to demonstrate that as levels of the high-sensitivity CRP went from low to high, the risk of having a heart attack (MI) went up quite dramatically over the next 8 years of these men's lives. And... in this case "these men" was me!
If we fast-forward to 2003, there are now 16 large-scale, prospective epidemiologic studies. These studies derive from large-scale cohorts around the world. And this phenomenon has been true in every study evaluated. Your CRP level, when you are healthy, predicts very dramatically the risk of future hear attacks and strokes. This was true for heart attack, stroke, peripheral arterial disease, and fatal stroke. It's true in the Framingham Heart Study. It's true in Europe. It's true in Japan. Every group studied has been highly consistent.
The really weird thing is this... HS-CRP, the marker for inflammation, predicts heart attacks and strokes but not cancer or the risk for other inflammatory diseases like rheumatoid arthritis, lupus, etc. BUT! HS-CRP also does a great job of predicting the risk of developing one other disorder...
the next paragraph can be safely skipped, well... actually... truth be known, the whole post can be safely skipped... but I digress, back to writing
With funding from the National Heart, Lung, and Blood Institute (NHLBI), a study was done that simply asked the question, "How well does a series of markers predict risk in blood samples stored at study entry among individuals who were followed into the future to have hard cardiovascular end points (that would be heart attacks and strokes)?" They discovered the markers that many were interested in -- lipoprotein(a) [Lp(a)] and homocysteine -- were rather weak predictors. There's interleukin-6, total cholesterol, and our gold standard for LDL cholesterol screening, highly significant but a modest predictor in the overall scheme of things. There is intercellular adhesion molecule (ICAM)-1 and adhesion molecules, and serum amyloid A, an alternative acute-phase reactant. For apolipoprotein (apo) B, there is the evidence it's a very good marker. The total cholesterol-to-high-density lipoprotein (HDL) cholesterol ratio is another way of getting at the issues of total and HDL combined.
The big surprise was this... the single best predictor of future trouble had nothi