ThePoliticalCat

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Thursday, January 10, 2008

Science: Snippets

From Science News, snippets of information found in Vol. 172:

Correction: The information that follows is actually from Vol. 171.

Caveat: The information that follows is my understanding of articles found in Science News. Limitations of space and time have resulted in a precis of the information published. For a better understanding of the information, please go to Science News online, or subscribe to their fine weekly magazine.


Researchers in West Africa have discovered remnants of a chimpanzee stone age civilization dating back 4300 years. More than 200 stone artifacts were found in Tai National Park in Cote d'Ivoire, used to crack open nuts, according to archaeologist Julio Mercader of the University of Calgary in Alberta and his colleagues. The age of the artifacts was estimated using radiocarbon measurements of burned wood in the soil. The artifacts were identified as implements in a blind test that included tools from a 5,000-year old human site and rocks from a site that had been modified by geological forces only. Starch grains extracted from the stones were shown to come from nuts typically eaten only by chimps. Archaeologist Alison S. Brooks of George Washington University in Washington, D.C., agrees with Mercader's postulation that further research may show evidence of even older chimpanzee sites, and points out that starch grains last well over 100,000 years. Archaeologist John J. Shea of the State University of New York at Stony Brook believes that chimpanzees probably invented the technique on their own rather than inheriting it from a common human-chimpanzee ancestor.


Approximately one in five patients on aspirin and warfarin due to severe narrowing of brain arteries will suffer a stroke or die of a vascular problem within two years, according to Science News. To counter such dismal statistics, scientists have adapted stents, long used to keep heart arteries open, to fit brain arteries which are smaller and more fragile than heart arteries. Jiang Wei Jian, a cardiologist at Beijing Tiantan Hospital reports that Chinese researchers have placed bare metal stents in the brains of 213 patients who had suffered strokes or ministrokes resulting from atherosclerosis which reduced the diameter of a brain artery by more than half. In the two years following such stenting, only 9 per cent of treated patients experienced a stroke.

Osama O. Zaidat, a neurologist at the Medical College of Wisconsin in Milwaukee coauthored a study on 131 patients who had a brain artery with 82 per cent blockage who had already suffered a stroke or ministroke. After being treated with a newer, more flexible stent that springs open at the target cite, their blockage was reduced to an average size of 20 per cent.

A third study showed that only 2 out of 59 patients who received drug-coated metal stents to treat severely narrowed arteries suffered a stroke within the four months after the procedure. Almost all the stented arteries remained open, says study coauthor Tudor G. Jovin, a neurologist at the University of Pittsburgh Medical Center. Researchers plan to do an efficacy trial next.


Each person who has cancer shows a particular pattern of genetic changes in their cells. These changes vary from person to person even when two individuals are suffering the same type of cancer. However, the genetic screening of tumours is expensive because current techniques sequence a single gene at a time, and hundreds of cancer-related mutations might need to be screened. Levi Garraway and his colleagues at Dana-Farber Cancer Institute in Boston have developed a way to screen multiple genes simultaenously with a degree of sensitivity hitherto unknown. The wide variety of mutations that the group found underscores the vast and poorly understood complexity of tumour genetics. Garraway expects the number of therapies targeted to specific cancers to grow rapidly in the next few years. Question: To whom will these therapies be available?


Science News tells us that lightning flashes occur 65 times per second worldwide. Each lightning bolt releases an amount of energy similar to a quarter ton of TNT, heating the air to approximately 30,000C (five times the temperature of the surface of the sun). When lightning strikes sand, it can melt and fuse sand and other materials into masses called fulgurites. Fulgurites, according to Rafael Navarro-Gonzales, a geochemist at the National Autonomous University of Mexico in Mexico City, when subjected to chemical analysis, can reveal details about the landscape in which they formed. For example, satellite data show very little lightning between 1998 and 2005 in the desert of southwestern Egypt. However, the fulgurites found in that desert prove that lightning frequently struck the area sometime in the past. A particular fulgurite being studied dates back 15,000 years, at which time the desert in which it was found supported shrubs and grasses similar to those found today in southwestern Niger, 600 km south.


Michael Longaker, a pediatric craniofacial surgeon at Stanford University School of Medicine in Palo Alto, CA, has been working with his colleagues on a mouse gene called glycogen synthase kinase-3B (GSK-3B). Previous studies have linked this gene to palate and breastbone development and Longaker and his colleagues hoped to show how to prevent cleft palates by acting on this gene. The researchers engineered mice with a chemical tag on the relevant gene that made the protein produced by the gene degrade rapidly. Such mice, like those engineered to lack the gene altogether, developed cleft palates and malformed breastbones and died at birth. However, when a drug named rapamycin (which prevents the GSK-3B protein from degrading) was administered to the mothers of such mice throughout pregnancy, the resulting mice did not suffer from the birth defects. Most interestingly, the timing of the dosage showed different effects. In order to prevent cleft palates, the mousy mothers needed the drug between 13.5 and 15 days after gestation. To prevent breastbone defects, the mousy mothers needed the drugs between days 15.5 and 17.

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