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Research round-up

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Exercise and stroke

June 15, 2000

NEW YORK, June 15 (Praxis Press) Increased physical activity is associated with reduction in risk of coronary heart disease. The role of physical activity in the prevention of stroke, however, is less well established. To examine the association between physical activity and risk of total stroke and stroke subtypes in women, investigators examined 72,488 women aged 40 to 65 years without cardiovascular disease or cancer at the beginning of the study in 1986. The women completed detailed physical

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NEW YORK, June 15 (Praxis Press) The risk of sudden death is a possible consequence of hypertrophic cardiomyopathy but has not been quantified for most patients with this disease. Spirito and colleagues examined the relationship between the magnitude of left ventricular hypertrophy and mortality in 480 consecutive patients with hypertrophic cardiomyopathy (see abstract). They found that the risk of sudden death increased progressively and in direct relation to wall thickness. Young patients with

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Polypectomy surveillance

June 15, 2000

NEW YORK, June 15 (Praxis Press) Whether colonoscopy is more effective than barium enema for the detection of adenomas in polypectomy patients is unclear. Winawer and colleagues examined 580 polypectomy patients and performed 862 paired colonoscopies and barium-enema examinations (see abstract). One or more adenomas were detected in 28 percent of the colonoscopies. Out of those 28 percent, barium enemas were only positive for 39 percent of them. In addition, the rate of detection for barium enem

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Primary angioplasty

June 14, 2000

NEW YORK, June 14 (Praxis Press) Rapid reperfusion after acute myocardial infarction (MI) using thrombolytic therapy reduces mortality, but whether time to primary angioplasty is also related to mortality is unclear. Investigators examined 27,080 patients with acute MI associated with ST-segment elevation or left bundle-branch block who were treated with angioplasty (see paper). Cannon and colleagues found that the odds of in-hospital mortality increased from 41% to 62% when the time to primary

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Sunscreen and nevi

June 14, 2000

NEW YORK, June 14 (Praxis Press) Melanocytic nevi originate in childhood and are mainly caused by exposure to the sun. High nevus density is a risk factor for cutaneous malignant melanoma. Investigators examined 309 white schoolchildren over a period of three years. The children's parents received directions to apply SPF 30 broad-spectrum sunscreen to exposed sites when the child was expected to be in the sun for 30 minutes or more. Children in the sunscreen group developed fewer nevi than contr

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TB transmission

June 14, 2000

NEW YORK, June 14 (Praxis Press) Despite improvements in tuberculosis (TB) control during the past decade, Mycobacterium tuberculosis transmission continues to occur in the United States. Chin and colleagues examined 221 TB case-patients in the San Francisco Bay area and found that seventy-three resulted from one strain of M tuberculosis. Thirty-nine of the 73 case-patients developed TB because they were not identified as contacts of source case-patients; 20 case-patients developed TB because of

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Sharing transcription duties

By | June 13, 2000

The transcription factors TFIID and SAGA are multi-subunit complexes involved in RNA polymerase II transcription. In the 8 June Nature Lee et al. use oligonucleotide arrays to analyze the relative requirement for the two complexes in yeast (Nature 2000, 405:701-704). Expression of about 70% of yeast genes requires one or more of the subunits shared between TFIID and SAGA, although individual subunits were required to varying extents, and no single subunit was required to the same extent as RNA p

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The birth of AIDS

By | June 13, 2000

According to a new phylogenetic analysis, the subtype of HIV that causes the majority of AIDS cases started diverging around 1931. The results of the analysis, which was conducted on the Los Alamos supercomputer 'Nirvana' using sequences from 159 envelope genes, are reported in the 9 June Science (Korber et al., Science 2000, 288:1789-1796). The computation used a molecular clock model presuming a constant rate of sequence change, but similar results were obtained with models that allowed change

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A lot of bloody genes

By | June 7, 2000

In the 2 June Science, Phillips et al announce the creation of the Stem Cell Database (SCDb), an annotated collection of genes expressed in hematopoietic stem cells (Science 2000, 288:1635-1640). Most of the data are based on the sequencing of 5735 clones from a subtracted stem cell library, representing at least half of the library's complexity. The SCDb reveals clues to stem cell biology, such as the coincidence of semaphorins and their ligands, suggesting that these molecules are important fo

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Gene, regulate thyself

By | June 7, 2000

The stochastic nature of every chemical event in the cell generates noise that can lead to large fluctuations in protein and mRNA levels. Autoregulatory negative feedback loops in gene circuits have been proposed, but never shown, to be one way of limiting this variation. With a simple experiment, in the 1 June Nature Becskei and Serrano demonstrate that negative feedback can decrease the inherent variability of gene expression more than threefold. They direct expression of a hybrid protein (gre

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