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Mad Cow Disease

In 1986, the first case of 'mad cow' disease or bovine spongiform encephalopathy (BSE) was found in cattle in Great Britain. Irritable personalities, fearful behavior, and a staggering gait preceded death in affected cows. Autopsies showed holes in their brain tissue. Food scientists thought the cows got BSE from their feed. The feed contained meat ...

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MadCowDisease
Astronomy

Mission: Gather Comet Dust; Return To Earth

One of the most imaginative NASA missions of recent years is the Stardust mission. Its main purpose: to gather dust and particles from comet P/Wild 2 and return them to Earth for study. Think about ... Continue reading

CometDust
Biology

What’s So Different About Ferns?

Most plants reproduce by producing a flower, then seeds. Anthers, considered the male reproductive structure, hold the pollen. The ovum, the female reproductive structure inside the flower, is ... Continue reading

Ferns
Biology

Flu Pandemics in the 20th Century

If a flu virus emerges that is either new or that has not circulated in many years, and if it is able to spread easily from person to person, it could quickly travel around the world and cause serious ... Continue reading

FluPandemics
Chemistry

Exploding Fertilizer

Atmospheric nitrogen is a diatomic molecule of just two nitrogen atoms bonded very strongly to each other. Nitrogen, in compound with other elements, is just a single nitrogen atom bonded very weakly, ... Continue reading

ExplodingFertilizer

Facts About Angina

FactsAboutAnginaAngina is a recurring pain or discomfort in the chest that happens when some part of the heart does not receive enough blood. It is a common symptom of coronary heart disease (CHD), which occurs when vessels that carry blood to the heart become narrowed and blocked due to atherosclerosis Angina feels like a pressing or squeezing pain, usually in the chest under the breast bone, but sometimes in the shoulders, arms, neck, jaws, or back. Angina is usually precipitated by exertion. It is usually relieved within a few minutes by resting or by taking prescribed angina medicine. Episodes of angina occur when the heart's need for oxygen increases beyond the oxygen available from the blood nourishing the heart. Physical exertion is the most common trigger for angina. Other triggers can be emotional stress, extreme cold or heat, heavy meals, alcohol, and cigarette smoking.

An episode of angina is not a heart attack. Angina pain means that some of the heart muscle in not getting enough blood temporarily--for example, during exercise, when the heart has to work harder. The pain does NOT mean that the heart muscle is suffering irreversible, permanent damage. Episodes of angina seldom cause permanent damage to heart muscle. In contrast, a heart attack occurs when the blood flow to a part of the heart is suddenly and permanently cut off. This causes permanent damage to the heart muscle. Typically, the chest pain is more severe, lasts longer, and does not go away with rest or with medicine that was previously effective. It may be accompanied by indigestion, nausea, weakness, and sweating. However, the symptoms of a heart attack are varied and may be considerably milder.

When someone has a repeating but stable pattern of angina, an episode of angina does not mean that a heart attack is about to happen. Angina means that there is underlying coronary heart disease. Patients with angina are at an increased risk of heart attack compared with those who have no symptoms of cardiovascular disease, but the episode of angina is not a signal that a heart attack is about to happen. In contrast, when the pattern of angina changes--if episodes become more frequent, last longer, or occur without exercise--the risk of heart attack in subsequent days or weeks is much higher.