Biomedical subjects
Publications and source records attributed to G Vogel.
Before the Bandiagara Malaria Project began, parents did not consult the local doctor but rather the traditional healers when a child developed cerebral malaria. So the researchers proposed a plan: When parents brought their children to the traditional healers, the healers would refer the children to the researchers for treatment with intravenous quinine and pyrimethamine-sulfadoxine, better known as Fansidar.
No one knows what causes depression, although many neuroscientists blame an imbalance of brain chemicals, so-called neurotransmitters, especially those that affect the brain's pleasure responses. Now a few neuroscientists are converging on a radical, but complementary, theory: that depression may be caused by a lack of new cell growth in the brain. The recent discovery that the brain keeps producing neurons into adulthood has given this highly speculative theory at least one leg to stand on.
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Whole-genome association studies will be a powerful tool to identify genes responsible for common human diseases. A crucial task for association-mapping studies is the evaluation of the relationship between linkage disequilibrium (LD) and physical distance for the genomic region under study. Since it is known that the extent of LD is nonuniformly distributed throughout the human genome, the required marker density has to be determined specifically for the region under study. These regions may be related to isochores and chromosomal bands, as indicated by earlier cytogenetic findings concerning chiasma distribution in meiosis. Therefore we analyzed the neurofibromatosis type 1 (NF1) gene region on chromosome 17q11.2, which is characterized by a nonuniform LD pattern and an L1-to-H2 isochore transition. Long-range LD within the NF1 gene was found to extend over 200 kb (D' = 0.937) in the L1 isochore, whereas, in the neighboring H2 isochore, no LD is apparent between markers spaced by 26 kb (D' = 0.144). Recombination frequencies derived from the LD are at.00019 (high LD) and.01659 (low LD) per megabase, the latter identical to the average value from segregation analysis. The boundary between these regions coincides precisely with a transition in the GC content of the sequences, with low values (37.2%) in the region with long-range LD and high values (51%) in the other. Our results suggest a correlation between the LD pattern and the isochores, at least in the NF1 region. If this correlation can be generalized, the marker densities required for association studies have to be adjusted to the regional GC content and may be chosen according to the isochores.
The National Institutes of Health (NIH) issued final guidelines last week allowing NIH-funded researchers to derive human pluripotent stem cells from fetal tissue, but not from embryos. Scientists may also work with embryonic stem cells, but may obtain them only from private sources and must ensure that derivation meets certain ethical conditions. The NIH spent nearly a year finalizing the guidelines, which researchers hope will allow work leading to the improved treatment of diabetes, Parkinson's, and other diseases.
Fourteen years ago, Congress declared the Southern California coast an otter-free zone--but the unwitting creatures aren't cooperating. That's no surprise to federal biologists, who this summer issued a report concluding that the otter-free zone harms the already-endangered population. Federal officials are now trying to come up with a better plan, but it's likely to draw from politics as well as science.
BOULDER, COLORADO--Nearly 600 scientists gathered at the base of the Flatirons to discuss the growth and patterning of organisms including plants, worms, fruit flies, fish, and mice at the 59th annual meeting of the Society for Developmental Biology. Among the highlights were clues about how blind cave fish lost their eyes and how a gene that influences cell movement might help cancer spread.
Often left out of news reports of cloned animals is the fact that for every 100 attempts, just two or three live offspring typically result. Now many researchers are going back to the lab to attempt to find out why. They are probing fundamental questions of cell biology, as well as trying to figure out whether there is something inherently flawed in "asexual" reproduction in mammals, or whether some problem lies in the in vitro component of the process. For now, the serious obstacles suggest that human cloning may be a long way off.
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We have reexamined the structure of inositol phosphates present in trophozoites of the parasitic amoeba Entamoeba histolytica and show here that, rather than being myo-inositol derivatives (Martin, J.-B., Bakker-Grunwald, T., and Klein, G. (1993) Eur. J. Biochem. 214, 711-718), these compounds belong to a new class of inositol phosphates in which the cyclitol isomer is neo-inositol. The structures of neo-inositol hexakisphosphate, 2-diphospho-neo-inositol pentakisphosphate, and 2, 5-bisdiphospho-neo-inositol tetrakisphosphate, which are present in E. histolytica at concentrations of 0.08-0.36 mM, were solved by two-dimensional (31)P-(1)H NMR spectroscopy. No evidence for the co-existence of their myo-inositol counterparts has been found. These neo-inositol compounds were not substrates of 6-diphospho-inositol pentakisphosphate 5-kinase, an enzyme purified from Dictyostelium discoideum that phosphorylates 6-diphospho-myo-inositol pentakisphosphate and more slowly also myo-inositol hexakisphosphate, specifically on position 5. Because preliminary data indicate that large amounts of the same neo-inositol phosphate and diphosphate esters are also present in another primitive amoeba, Phreatamoeba balamuthi, the occurrence of high concentrations of neo-inositol polyphosphates may be much more general than previously thought.
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