Jumat, 31 Juli 2009

What Happened to the Neandertals?

The cover story of the August 2009 issue of Scientific American discusses the latest evidence and hypotheses for why the archaic humans called the Neandertals disappeared from Europe around 28,000 years ago. Older theories, that the Neandertals either interbred with modern humans or died in wars against them (the love versus war hypotheses), seem to be losing favor. A more recent hypothesis is that there were frequent and rapid changes in climate in Europe at the time, and that modern humans, by virtue of being more advanced in certain ways, were better able to adapt to the changes in weather and food supplies. The article goes on to describe the likely cultural, behavioral, and biological differences between the Neandertals and modern humans who lived in Europe 35,000 years ago, and how these differences might have affected modern humans’ success or the Neandertals’ ultimate failure.

Sabtu, 25 Juli 2009

Birth Control Method Failures

In Human Biology 5th ed. (p. 387) there’s a table of data provided by the U.S. Food and Drug Administration on the failure rates of various contraceptive methods. I’ve always felt that the reported failure rate for condoms of 10-20% seemed awfully high. Condoms are supposed to work, right?

Now there’s an explanation. Recent evidence shows that for both condoms and withdrawal, there’s a big difference between “perfect use” and “typical use”. If a couple actually uses a condom every time (no exceptions, folks), the annual failure rate is only about 2%. For withdrawal every time, the failure rate is about 4%. The problem is that in the heat of passion some couples “forget”, or convince themselves that not using a birth control method just this once won’t be a big deal. Under these more typical use conditions, the failure rates of condoms and of withdrawal are indeed closer to 20% per year.

If you’re going to rely on these contraceptive methods, don’t cheat!

REFERENCE: R.K. Jones. Better than nothing or savvy risk-reduction practice? The importance of withdrawal. Contraception 79:407-410, June, 2009.

Senin, 20 Juli 2009

Percocet, Vicodin May be Banned

A federal panel of experts advised the Food and Drug Administration (FDA) this month to ban two popular prescription painkillers, Percocet and Vicodin, from the market. The panel also recommended that the maximum allowable dose of acetaminophen in over-the-counter pills such as Tylenol be reduced from 500 mg to 325 mg. The FDA is expected to accept the panel’s recommendations.

Percocet and Vicodin are comprised acetaminophen plus a narcotic. According to the panel of experts, there is now sufficient evidence to conclude that high doses of acetaminophen over prolonged periods of time can cause liver damage.

It's worth noting that nearly all drugs, even some very good ones, can have unwanted side effects if they are abused.

You can read or see the news reports on the panel’s findings by Googling “FDA”, “Percocet”, and “acetaminophen”.

Minggu, 19 Juli 2009

Getting That Caffeine Buzz

The latest entry into the world of marketing hype - “energy shots”, a mere two ounces of bad-tasting liquid loaded with caffeine. Manufacturers won’t say how much caffeine for proprietary reasons (and probably to add to the drinks’ mystique), but most energy shots are thought to contain on the order of 120-200 mg. That’s the equivalent of one to two ordinary cups of coffee or a 16-oz energy drink.

Energy shots may also contain B-vitamins, amino acids and various plant extracts, but these aren’t likely to give you much of an energy boost despite the products’ claims. And then there’s the cost – upwards of $3 apiece.

If it’s a caffeine buzz you need, what’s wrong with plain-old maximum strength (200 mg) No-Doz? It was your grandfather’s drug of choice nearly 50 years ago for pulling an all-nighter, and it still works. Plus it only costs about 20 cents per dose.

Selasa, 14 Juli 2009

PHYSORG ARTICLE: APOPTOSIS - Scientists provide important insight into apoptosis or programmed cell death

But first, a refresher on A-POP-TO-SIS

Quoted from: http://www.physorg.com/news166786296.html:
A study by Nanyang Technological University (NTU)'s Assistant Professor Li Hoi Yeung, Assistant Professor Koh Cheng Gee and their team have made an important contribution to the understanding of the process that cells go through when they die. This process known as 'apoptosis' or programmed cell death, is a normal process in the human body which removes perhaps a million cells a second.

According to Professor Li, they discovered that during apoptosis, the cell's rescue mechanism is inhibited when certain proteins (i.e. 'anti-factors' that are necessary to keep a cell alive) are no longer able to enter the cell's nucleus, thus stopping the cell's ability to initiate its self-repair process.

In addition, they also discovered that the protein RanGTP, which is involved in the transportation of certain proteins into and out of the cell's nucleus, is reduced greatly during the early stages of apoptosis.

Under normal circumstances, there is a high distribution of RanGTP in the nucleus and a low concentration of RanGTP in the (the body enveloping the cell's nucleus). It is this gradient of RanGTP that exist across the nuclear-cytoplasmic boundaries that serves as a track and directs the transport of proteins and other molecules into and out of the nucleus. Hence, when the concentration of RanGTP is reduced in the nucleus, the RanGTP gradient collapses and the nuclear transport machinery subsequently shuts down.

Too little or too much apoptosis plays a role in a great many diseases. When does not work right, cells that should be eliminated may linger around and become immortal - for example, in cancer and . When apoptosis works overly well, it kills too many cells and inflicts grave . This is the case in strokes and neurodegenerative disorders such as Alzheimer, Huntington and Parkinson diseases.

While it is established that cells undergo apoptosis when they are damaged by mechanical injury, exposed to death stimuli, or under stress, the mechanism that initiates apoptosis has not been comprehensively resolved. Thus the study by Professor Li, Professor Koh and their team at NTU have provided new insights on the process that cells go through while experiencing apoptosis.

And, from the Archives, here's some more info about
Introduction lecture to apoptosis Xiaodong Wang, Apoptosis
A collection of videos about apoptosis: http://bio-alive.com/categories/apoptosis.htm
Full Text lab methodology papers on: Apoptosis (7)

Sabtu, 11 Juli 2009

Caloric Restriction and Longevity

It has been known for some time that severe caloric restriction can retard the aging process and prolong the life of a variety of species, from worms to mice. But skeptics of the idea that caloric restriction might also slow the aging process in humans point out that the metabolisms of worms and mice are quite different from that of humans.

Now a new study reports that caloric restriction slows the aging process in primates, too. Macaque monkeys that have been on a calorie-restricted diet (by 30%) for the past 20 years are living longer and are healthier than their age-matched control counterparts. Excluding animals that died of non-age-related causes (accidents for example), 50% of the animals on a normal diet have died of age-related causes, compared to only 20% in the restricted-diet group. The calorie-restricted animals also have fewer age-associated diseases such as diabetes, cancer, and cardiovascular disease. The study is still ongoing.

Rabu, 08 Juli 2009

Wildfires, Evolution, and Ecosystems

Fires set by the forces of nature have existed on the Earth since the dawn of time, and as a result some plants have evolved to survive fires rather well. A few plants even require an occasional fire in order to release their seeds. But here’s an interesting notion; did certain plants evolve to encourage the spread of wildfires once they’ve started? After all, if the plant could survive the fire it might be a good way to kill off the competition. For those of you interested in evolutionary processes, see the recent well-referenced opinion article in the New York Times.

Minggu, 05 Juli 2009

Swine Flu Takes Hold in Argentina

Swine flu just won’t go away. A recent a sharp uptick in the number of deaths from swine flu in Argentina has moved that country into third place for the most swine flu deaths, after Mexico and the United states. And the timing couldn’t be worse; it’s winter in South America, the season when influenza viruses typically spread the easiest. Of special concern is that the death rate in Argentina (1.6%) is more than three times the world average.

We need to keep an eye on this pesky bug. Who knows what it could do in North America NEXT flu season? For the latest information on swine flu (also now called Pandemic H1N1), see the World Health Organization website.
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