Cholesterol Watch

SEPTEMBER 01, 2007

Diesel Fumes Can Prompt Clogged Arteries

Scientists have found a biochemical process that makes exhaust from diesel engines a danger to human arteries. An interaction between the fine particles found in diesel smoke and the fatty acids in low-density lipoproteins (LDLs) triggers genes that cause inflammation in the blood vessels. The process speeds up atherosclerosis.

The mechanism is one way that ?chemicals in diesel exhaust impact the cardiovascular (CV) system,? according to researchers at the University of California, Los Angeles. Their research was reported in the July 26, 2007, online edition of Genome Biology.

The investigators conducted a series of studies in which they combined particulate diesel pollutants with fatty acids found in LDLs and studied how the substances interacted with free radicals. They exposed cells to the mixture and extracted genetic material from the cells.

The researchers found that the genes that promote the inflammation of cells were highly activated by the exposure. They concluded that ?for people who have CV risk factors . . . exposure to diesel air pollution can enhance damage.?

High Triglycerides Linked to Heart Risk

A finding by researchers in both Denmark and the United States shows that high levels of triglycerides are associated with an increased risk of cardiovascular (CV) problems, but only if they are measured in the hours right after a meal.

The Denmark study found no relationship when the levels were tested in the usual manner: after a 12- to 14-hour fast. The nonfasting results, however, were considerably different: women with the highest triglyceride levels when tested after a meal had up to 5 times the risk of dying from a heart attack or other CV event as those with the lowest levels; men had twice the risk.

The American study looked at more than 25,000 participants in the Women?s Health Study who were followed for an average of 11 years. This study found that women with high triglyceride levels soon after a meal had a 44% increased risk of a CV event. This risk decreased steadily with time, disappearing after ~4 hours.

The results of both studies were published in the July 18, 2007, issue of the Journal of the American Medical Association.

Cancer Risk from Low Cholesterol Extremely Small

Researchers at Tufts University School of Medicine conducted a meta-analysis of 23 different trials involving statins. The researchers examined the records of 41,173 patients to determine adverse effects and found that there was a slight increase in cancer incidence in 13 trials.

This finding involved patients who achieved the lowest low-density lipoprotein levels, and it did not entail any specific type or location of cancer.

The actual incidence of cancer among statin users was about 1 in every 1000 patients. The study appeared in the July 31, 2007, issue of the Journal of the American College of Cardiology.

The researchers emphasized that this information was not significant enough to recommend the cessation of statin use. ?Most studies don?t get cholesterol levels low enough,? said John C. LaRosa, MD, professor of medicine and president at the State University Downstate Medical Center in Brooklyn, NY, who wrote an editorial on the study. The benefits of statins far outweigh the risk, and ?this data is hardly conclusive of anything real enough to cause a change.?

Higher Doses of Statins Cut Elderly Heart Risk

The aggressive lowering of low-density lipoprotein (LDL) levels with high doses of atorvastatin reduces the risk of cardiovascular (CV) events in elderly patients with coronary disease more than lower doses.

The researchers analyzed the data on about 3800 patients, aged 65 years or older, who were part of a group of 10,000 patients with coronary disease participating in a clinical trial of atorvastatin.

All the patients had LDL levels below 130 mg/dL. They were randomly assigned to receive either 10 mg or 80 mg of the statin per day. The usual target LDL level is <100 mg/dL, but patients with actual coronary heart disease are encouraged to keep their levels even lower.

The researchers found that those on the higher statin dose reduced their LDL levels to ~70 mg/dL, while those who took the lower dose reduced their levels to ~100 mg/dL. The risk of suffering a stroke, heart attack, or cardiac arrest was lowered by 19% in those taking the 80-mg dose. The findings were published in the July 3, 2007, issue of the Annals of Internal Medicine.