San Diego State University

About: San Diego State University is a education organization based out in San Diego, California, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 12418 authors who have published 27950 publications receiving 1192375 citations. The organization is also known as: SDSU & San Diego State College.

Abnormalities of the Corpus Callosum in Children Prenatally Exposed to Alcohol

Abstract: For 20 years, it has been known that fetal alcohol syndrome (FAS) is associated with abnormal brain development. Early autopsy studies point to the corpus callosum as one area affected by heavy alcohol exposure. Little is known, however, about the integrity of the brain in alcohol-exposed children who survive the perinatal period. This study was designed to assess the corpus callosum in living children exposed to high doses of alcohol prenatally. Thirteen children with histories of significant prenatal alcohol exposure and 12 normal control children were evaluated using magnetic resonance imaging. Using the midsagittal section, images were measured for the area of the corpus callosum using a computer-assisted measurement technique. In addition to the overall area, five equiangular regions were determined for each corpus callosum. Of the 13 alcohol-exposed children assessed, two had agenesis of the corpus callosum. The remaining alcohol-exposed children had significantly smaller overall callosal areas, as well as smaller regional areas of four of the five callosal regions, when compared with the normal control children. Importantly, when corrected for brain size, three of the five callosal regions were still smaller in the alcohol-exposed children, although overall area of the corpus callosum was no longer significantly different. These results suggest that prenatal exposure to high levels of alcohol is associated with abnormalities of the corpus callosum. They verify callosal agenesis in children with FAS, which previously had only been noted in autopsy reports.(ABSTRACT TRUNCATED AT 250 WORDS)

Human amplification of drought-induced biomass burning in Indonesia since 1960

Abstract: Under drought conditions, biomass burning in Indonesia is a disproportionate contributor to the global carbon dioxide emissions from such events. An analysis of Indonesian records of large fires shows that their occurrence is linked to land use and population dynamics, and that the Indian Ocean climate and El Nino both have an equally important influence. Much of the interannual variability in global atmospheric carbon dioxide concentrations has been attributed to variability of emissions from biomass burning1,2,3. Under drought conditions, burning in Indonesia is a disproportionate contributor to these emissions, as seen in the 1997/98 haze disaster1,4. Yet our understanding of the frequency, severity and underlying causes of severe biomass burning in Indonesia is limited because of the absence of satellite data that are useful for fire monitoring before the mid-1990s. Here we present a continuous monthly record of severe burning events from 1960 to 2006 using the visibility reported at airports in the region. We find that these fires cause extremely poor air quality conditions and that they occur only during years when precipitation falls below a well defined threshold. Historically, large fire events have occurred in Sumatra at least since the 1960s. By contrast, the first large fires are recorded in Kalimantan (Indonesian Borneo) in the 1980s, despite earlier severe droughts. We attribute this difference to different patterns of changes in land use and population density. Fires in Indonesia have often been linked with El Nino1,2,5,6,7,8,9,10,11,12, but we find that the Indian Ocean Dipole pattern is as important a contributing factor.

Why does a trait evolve multiple times within a clade? Repeated evolution of snakelike body form in squamate reptiles

Abstract: Why does a trait evolve repeatedly within a clade? When examining the evolution of a trait, evolutionary biologists typically focus on the selective advantages it may confer and the genetic and developmental mechanisms that allow it to vary. Although these factors may be necessary to explain why a trait evolves in a particular instance, they may not be sufficient to explain phylogenetic patterns of repeated evolution or conservatism. Instead, other factors may also be important, such as biogeography and competitive interactions. In squamate reptiles (lizards and snakes) a dramatic transition in body form has occurred repeatedly, from a fully limbed, lizardlike body form to a limb-reduced, elongate, snakelike body form. We analyze this trait in a phylogenetic and biogeographic context to address why this transition occurred so frequently. We included 261 species for which morphometric data and molecular phylogenetic information were available. Among the included species, snakelike body form has evolved about 25 times. Most lineages of snakelike squamates belong to one of two "ecomorphs," either short-tailed burrowers or long-tailed surface dwellers. The repeated origins of snakelike squamates appear to be associated with the in situ evolution of these two ecomorphs on different continental regions (including multiple origins of the burrowing morph within most continents), with very little dispersal of most limb-reduced lineages between continental regions. Overall, the number of repeated origins of snakelike morphology seems to depend on large-scale biogeographic patterns and community ecology, in addition to more traditional explanations (e.g., selection, development).