Form Of Cholesterol Singled Out As Cause Of Chest Pain, Heart Attack

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Form Of Cholesterol Singled Out As Cause Of Chest Pain, Heart Attack

http://www.sciencedaily.com/releases/2001/04/010417075529.htm

DALLAS, April 17 – In the first study of its kind, researchers have found that

blood levels of the oxidized form of low

density lipoprotein (LDL) are directly related to the severity of heart disease,

according to a report in today’s

Circulation: Journal of the American Heart Association.

In the two-part study, Japanese researchers also found that oxidized LDL was

higher in the plaques of individuals with

unstable angina than those with stable angina. Oxidized LDL (ox-LDL) is a form

of LDL that has combined with oxygen. It

is considered more dangerous than LDL because it promotes clogging of blood

vessels. Stable angina is chest pain that

occurs during exertion. People with unstable angina experience chest pain even

while at rest.

" It is accepted that inflammation within the plaque plays a key role in

destabilizing the lesions, which leads to

coronary events such as heart attacks. Our findings not only support this

concept, but suggest a pivotal role of

oxidized LDL in this process. " says study author Makiko Ueda, M.D., professor of

pathology, Osaka City University

Medical School in Japan.

The first part of the study included 135 patients who had various signs and

symptoms of heart attack or angina. There

were 45 patients with heart attack, 45 patients with unstable angina, 45

patients with stable angina, and a control

group. The patients with heart attack were studied within 24 hours of the onset

of chest pain. Blood samples were taken

from all patients when they were admitted to the hospital.

Researchers found that average levels of ox-LDL in patients who had a heart

attack were 1.95 nanograms (ng) per 5

micrograms of LDL protein, compared to 1.19 ng/5 micrograms LDL for those with

unstable angina, 0.89 ng/5 micrograms LDL

for stable angina and 0.58 ng/5 micrograms LDL for controls. The more serious

the condition, the higher the oxidized

LDL. The researchers say this observation strongly suggests that the amount of

oxidized LDL in circulating plasma could

serve as a marker for cardiovascular events.

Levels of ox-LDL were measured using a " sandwich ELISA " test in which LDL is

separated from other lipids in the blood

plasma. The LDL is then combined with an anti-oxidized LDL monoclonal antibody,

which isolates oxidized LDL. A second

monoclonal antibody, called anti-apolipoprotein B antibody, is used to detect

additional oxidized LDL particles in the

plasma. The technique is able to identify tiny amounts of LDL particles and is

superior to other methods in obtaining a

sensitive and accurate measurement of ox-LDL.

For the second part of the study, researchers analyzed sections of coronary

arteries from 10 individuals with stable and

23 with unstable angina. The sections were taken directly from the area believed

to have caused the blockage responsible

for the chest pain. They gave the samples a score according to ox-LDL levels at

that site. They found that individuals

with unstable angina had an average ox-LDL score of 0.49 and those with stable

angina had an average score of 0.07.

" Our study of atherectomy specimens clearly demonstrates that oxidized LDL is

higher in the arterial plaque of patients

with unstable angina compared to those with stable angina, " says Ueda.

Sotirios Tsimikas, M.D., assistant professor of medicine, division of

cardiology, University of California at San Diego,

says this research is unique because it looks at different groups of patients

using the same LDL measurements.

" The levels of oxidized LDL circulating in the blood correlate well with the

severity of disease, " says Tsimikas. " The

sicker the patient, the higher the levels of circulating oxidized LDL,

indicating that it is a marker of atherosclerotic

plaques. "

Atherosclerosis is a narrowing of the arteries caused by plaques on the inner

lining. The plaques consist of LDL,

decaying muscle cells, fibrous tissue, clumps of blood platelets and

cholesterol.

When plaques are disrupted or rupture, the oxidation process is activated and is

reflected in circulating LDL.

In an editorial accompanying the study, Tsimikas and ph Witztum, M.D.,

professor of medicine and director of

endocrinology and metabolism at UCSD, suggest the Osaka study is another step

forward that may lead to the development

of a new diagnostic test to assess the risk of heart attack and discriminate

between patients at risk. At present, they

say the test probably cannot be applied outside the research setting.

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Good Health & Long Life,

Greg , http://optimalhealth.cia.com.au gowatson@...

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