Posted 13 March 2005 - 04:33 PM
Alcohol Dehydrogenase
Here's a toast to alcohol dehydrogenase. While recovering from the excesses of New Year's Eve, we might ponder the enzyme that ceaselessly battles the champagne that we consume. Alcohol dehydrogenase is our primary defense against alcohol, a toxic molecule that compromises the function of our nervous system. The high levels of alcohol dehydrogenase in our liver and stomach detoxify about one stiff drink each hour. The alcohol is converted to acetaldehyde, an even more toxic molecule, which is then quickly converted into acetate and other molecules that are easily utilized by our cells. Thus, a potentially dangerous molecule is converted, through alcohol dehydrogenase, into a mere foodstuff.
Forms and Functions
Our bodies create at least nine different forms of alcohol dehydrogenase, each with slightly different properties. Most of these are found primarily in the liver, including the beta3 form (PDB entry 1htb) and the similar enzyme from horse liver (PDB entry 6adh). The sigma form, available in PDB entry 1agn, is found in the lining of the stomach. Each enzyme is composed of two subunits, and quite remarkably, you can mix and match subunits between these different forms, creating mixed dimers that are still active. Ethanol is not the only target of these enzymes, they also make important modifications to retinol, steroids, and fatty acids. The range of different types of alcohol dehydrogenase ensures that there will always be one that is perfect for the current task.
Consequences
Alcohol dehydrogenase provides a line of defense against a common toxin in our environment. But this protection carries with it some dangers. Alcohol dehydrogenase also modifies other alcohols, often producing dangerous products. For instance, methanol, which is commonly used to "denature" ethanol rendering it undrinkable, is converted into formaldehyde by alcohol dehydrogenase. The formaldehyde then does the damage, attacking proteins and embalming them. Small amounts of methanol cause blindness, as the sensitive proteins in the retina are attacked, and larger amounts, perhaps a glassful, lead to widespread damage and death.
Posted 13 March 2005 - 05:16 PM
Posted 14 March 2005 - 07:03 AM
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Posted 14 March 2005 - 08:15 AM
Yes this is common "knowledge", and it is false. Although alcohol inhibits formation of connections between braincells and results in increased levels of GABA which acts inhibitory on brainfunction.I thought it was common knowledge alcohol "killed" brain cells....
Posted 15 March 2005 - 11:21 AM
Youth drinking may hasten heart trouble
For young people, drinking even a small amount of alcohol could increase the chances of developing heart disease, according to one of the largest studies to look at alcohol's effects before middle age.
The finding contrasts with the widely held view that drinking in moderation - around two drinks per day for men and one for women - can help protect against heart disease.
Researchers are confident that this holds true for people who are over about 55 and at risk of heart disease. But they are unclear whether the health benefits of alcohol begin to accrue early in life - or exactly what alcohol is doing in the body to produce its beneficial effects.
Using data from an ongoing study on heart disease, epidemiologist Mark Pletcher at the University of California, San Francisco, and his team probed the hearts of more than 3,000 people aged 33-45 years using a CAT scanner.
They searched for one of the earliest signs of heart disease - a hardening of the arteries that supply oxygen to the heart itself. They then matched this up with information collected between 1985 and 2001 on how much each person drank
Young at heart
The finding implies that drinking alcohol early in life does not rack up gradual benefits that will protect drinkers later on. "It suggests there is little to be gained at a young age," says Kenneth Mukamal, who studies alcohol and health at Harvard Medical School in Boston.
Instead, it backs the idea that a slug of liquor protects against heart disease in older people in a different way: by having almost immediate effects. It may, for example, cut the risk of a blood clot forming and choking off an artery.
The new study also confirms experts' view that binge drinking, defined as more than five drinks at one time, is harmful. Indeed, the researchers found it difficult to tell whether younger people who drank more were harming their arteries because of the total quantity they drank or because they tended to drink in binges
Public-health experts already believe that young drinkers gain little by drinking at a young age. Any positive effects on the heart are thought to be outweighed by the increased risk of cancer
Posted 05 January 2009 - 12:01 AM
, or New Year's Eve.Just a few sessions of heavy drinking can damage someone's ability to pay attention, remember things and make good judgments, research shows.
Binge drinkers are known to be at increased risk of accidents, violence and engaging in unprotected sex. But the study is the first to identify brain damage as a danger of consuming more alcohol than official safe limits.
The research, to be published in the journal Alcohol and Alcoholism, is significant because binge drinking is so widespread in the UK. Twenty-three per cent of men and 15% of women drink more than twice the government's recommended daily limit. For men this means consuming more than eight units a day and for women more than six, according to the Office for National Statistics.
Binge drinkers aged between 18 and 24 are a key target of the government's alcohol strategy because a minority of people in that age group cause the majority of alcohol-related crime and disorder.
Professor Ian Gilmore, president of the Royal College of Physicians, said: "We know large numbers of people in this country binge drink. This should be a wake-up call to the millions of people whose lifestyle means they get drunk regularly."
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