Catálogo de publicaciones - revistas

<jats:title>Vaginal Gel Versus HIV</jats:title> <jats:p> HIV prevention technologies for women are urgently needed, especially in sub-Saharan Africa where young women bear the greatest burden of the HIV epidemic. <jats:bold> Abdool Karim <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1168" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1193748">1168</jats:related-article> ; published online 19 July) present the results of the CAPRISA 004 randomized control trial. The nearly 3-year-long trial, conducted in urban and rural South African women, tested the efficacy of a vaginal gel containing the antiretroviral drug tenofovir in preventing HIV infection. The dosing strategy required application of the gel both before and after coitus, and with this regime HIV infection was reduced by approximately 39% overall, by 54% in women with high adherence to the protocol, and with no increase in overall adverse event rates. </jats:p>

<jats:title>Antimalarial Drug Candidate</jats:title> <jats:p> Spiroindolones were discovered as promising antimalarial drug candidates through a high-throughput screening approach that should be applicable to a range of neglected infectious diseases. <jats:bold> Rottmann <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1175" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1193225">1175</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5996" page="1153" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1194923">Wells</jats:related-article> </jats:bold> ) present the preclinical profile for an optimized spiroindolone drug candidate, NITD609. They obtained evidence for a decrease in drug sensitivity in strains of the malaria parasite <jats:italic>Plasmodium falciparum</jats:italic> bearing amino acid mutations in the P-type ATPase, indicating possible mechanisms of action and/or resistance. </jats:p>

<jats:title>Cosmic Fullerenes</jats:title> <jats:p> Since the discovery of the buckminsterfullerene C <jats:sub>60</jats:sub> in laboratory experiments, it has been speculated that fullerenes could form abundantly in carbon-rich evolved stars and, because of their stability, survive the harsh radiation field in the interstellar medium as a gas-phase species. <jats:bold> Cami <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1180" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1192035">1180</jats:related-article> ; published online 22 July; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5996" page="1159" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1194855">Ehrenfreund and Foing</jats:related-article> </jats:bold> ) have detected large amounts of fullerenes in a peculiar planetary nebula with an extremely hydrogen-poor dust formation zone. Contrary to expectations, the fullerenes are not gaseous; they are cool, are in a neutral charge state, and represent about 1.5% of the available carbon. </jats:p>

<jats:title>Free Falling Vortices</jats:title> <jats:p> When a vessel containing a superfluid is set in rotational motion, the superfluid does not rotate uniformly with it; instead, quantized vortices develop. Vortices have been observed in a range of superfluids, including helium, atomic Bose-Einstein condensates, and type II superconductors in a magnetic field. <jats:bold> Freilich <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1182" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1191224">1182</jats:related-article> ) visualized real-time vortex dynamics in the most tunable of superfluid systems, an atomic Bose-Einstein condensate. A small section of condensate was displaced from the trap and imaged as it fell in the gravitational field. The technique is applicable to exploring other complex dynamic systems, such as vortex reconnections and the role of vortices in quantum turbulence. </jats:p>

<jats:title>Sea of Plastic</jats:title> <jats:p> Plastics are highly resistant to degradation and persist in the environment after being discarded. Notoriously, plastics accumulate within ocean gyres, where patterns of surface circulation concentrate them into specific regions. One area of plastic buildup lies in the middle of the North Atlantic Gyre. <jats:bold> Law <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1185" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1192321">1185</jats:related-article> ; published online 19 August) report results from 22 years of plankton tows in the North Atlantic that showed the pattern of plastics accumulation was indeed as predicted by theories of ocean circulation, but, despite the steady increase in plastic production and disposal, the concentration of plastic debris had not increased. </jats:p>

<jats:title>Icy Adsorption</jats:title> <jats:p> The highly mobile nature of adsorbed liquid water on surfaces has made structural studies using atomic force microscopy challenging, especially for the first adsorbed layer. Moreover, scanning probe methods are hindered by the strong interaction between the probe tip and the water molecules. When graphene flakes were deposited on mica, <jats:bold> Xu <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1188" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1192907">1188</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5996" page="1157" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1195392">Katsnelson</jats:related-article> </jats:bold> ) found that they could use atomic force microscopy to image the first and second layers of introduced water. They consistently observed an islandike structure—0.34 nanometers in height, at low humidity—that corresponded to a single layer of ice. At higher humidity, thicker layers with a more liquid nature were observed. </jats:p>

<jats:title>No Guide to the Future</jats:title> <jats:p> Although fossils can provide glimpses of evolution, the accuracy for predictions made on the basis of commonality among geographically and hierarchically distinct taxa is unknown. <jats:bold>Alroy</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1191" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1189910">1191</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5996" journal-id="" page="1156" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1194924">Marshall</jats:related-article> </jats:bold> ) looked at the global marine fossil record and found that major taxonomic groups of animals have distinctive patterns of diversification and unpredictable responses to mass extinctions. Extrapolating from the current ongoing extinction event predicted a geologically rapid rebound of a number of species, although the future taxonomic composition of the marine biosphere could not be forecast. </jats:p>

<jats:title>Join the Club</jats:title> <jats:p> An important question for policy-makers is how to communicate information (for example, about public health interventions) and promote behavior change most effectively across a population. The structure of a social network can dramatically affect the diffusion of behavior through a population. <jats:bold>Centola</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1194" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1185231">1194</jats:related-article> ) examined whether the number of individuals choosing to register for a health forum could be influenced by an artificially constructed network of neighbors that were signed up for the forum. The behavior spread more readily on clustered networks than on random, poorly clustered ones. Certain types of behavior within human systems are thus more likely to spread if people are exposed to many other people who have already adopted the behavior (for example, in the circumstances where your friends know each other, as well as yourself). </jats:p>

<jats:title>Here to Stay</jats:title> <jats:p> For systemic infection, bacterial pathogens must breach the mucosal epithelial barrier. Our bodies have developed a variety of strategies to protect the mucosa, including rapid turnover of epithelial cells. <jats:bold> Muenzner <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1197" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1190892">1197</jats:related-article> ; see the cover) show how invasive bacteria overcome this host defense in a humanized mouse model susceptible to <jats:italic>Neisseria gonorrhoeae</jats:italic> urogenital infection. The bacteria bind to a host-cell surface protein called carcinoembryonic antigen (CEA), which triggers a cascade of changes modulating the cell adhesion properties of the targeted epithelium to prevent the cells from being shed. </jats:p>

<jats:title>Regulation of Energy Homeostasis</jats:title> <jats:p> The mammalian AMP-activated protein kinase (AMPK) is a serine/threonine kinase complex that regulates cellular energy homeostasis. However, the mechanisms by which AMPK mediates transcriptional responses to metabolic perturbations has been unclear. <jats:bold> Bungard <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1201" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1191241">1201</jats:related-article> ; published online 17 August; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="5996" page="1158" related-article-type="in-this-issue" vol="329" xlink:href="10.1126/science.1195447">Hardie</jats:related-article> </jats:bold> ) have found that AMPK activated transcription directly on chromatin, combined with phosphorylation of histone H2B at Serine-36. Both signals colocalized at genes regulated in the pathway, and both the enzyme and phosphorylation were required for the direct transcription of stress-responsive genes. </jats:p>