934 resultados para Crest


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Mutations in the gene encoding the endothelin receptor type B (EDNRB) produce congenital aganglionic megacolon and pigment abnormalities in mice and humans. Here we report a naturally occurring null mutation of the EDNRB gene in spotting lethal (sl) rats, which exhibit aganglionic megacolon associated with white coat color. We found a 301-bp deletion spanning the exon 1-intron 1 junction of the EDNRB gene in sl rats. A restriction fragment length polymorphism caused by this deletion perfectly cosegregates with the sl phenotype. The deletion leads to production of an aberrantly spliced EDNRB mRNA that lacks the coding sequence for the first and second putative transmembrane domains of the G-protein-coupled receptor. Radioligand binding assays revealed undetectable levels of functional EDNRB in tissues from homozygous sl/sl rats. We conclude that EDNRB plays an essential role in the normal development of two neural crest-derived cell lineages, epidermal melanocytes and enteric neurons, in three mammalian species--humans, mice, and rats. The EDNRB-deficient rat may also prove valuable in defining the postnatal physiologic role of this receptor.

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The hoatzin (Opisthocomus hoazin) lives in the humid lowlands of northern and central South America, often in riparian habitats. It is a slender bird approximately 65 cm in length, brownish with lighter streaks and buffy tips to the long tail feathers. The small head has a ragged, bristly crest of reddish-brown feathers, and the bare skin of the face is bright blue. It resembles a chachalaca (Ortalis, Cracidae) in size and shape, but its plumage and markings are similar to those of the smaller guira cuckoo (Guira guira). The hoatzin (pronounced Watson) has been a taxonomic puzzle since it was described in 1776. It usually has been viewed as related to the gallinaceous birds, but alliances to other groups have been suggested, including the cuckoos. We present DNA sequence evidence from the 12S and 16S rRNA mitochondrial genes, and from the nuclear gene that codes for the eye lens protein, alpha A-crystallin. The results indicate that the hoatzin is most closely related to the typical cuckoos and that the divergence occurred at or near the base of the cuculiform phylogenetic tree.

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A qualidade óssea, bem como a estabilidade inicial dos implantes, está diretamente relacionada com o sucesso das reabilitações na implantodontia. O presente estudo teve como objetivo analisar a correlação entre índices radiomorfométricos de densidade óssea por meio de radiografias panorâmicas, perfil de qualidade óssea com o auxílio de Tomografia Computadorizada de Feixe Cônico (TCFC) com o uso do software de imagens OsiriX, Análise da Frequência de Ressonância (RFA) e Torque de Inserção do implante. Foram avaliados 160 implantes de 72 indivíduos, com média etária de 55,5 (±10,5) anos. Nas radiografias panorâmicas foram obtidos os índices IM, IPM e ICM, e nas tomografias computadorizadas de feixe cônico, os valores de pixels e a espessura da cortical da crista óssea alveolar, além da estabilidade primária por meio do torque de inserção e análise da frequência de ressonância. Os resultados foram analisados pelo coeficiente de correlação de Spearman, para p<= 0,01 foi obtido entre o torque de inserção e valores de pixels (0.330), o torque de inserção e a espessura da cortical da crista alveolar (0.339), o torque de inserção e o ISQ vestibulo-lingual (0.193), os valores de pixels e espessura da cortical da crista alveolar (0.377), as duas direções vestíbulo-lingual e mesio-distal do ISQ (0.674), o ISQ vestíbulo-lingual e a espessura da cortical da crista alveolar (0.270); os índices radiomorfométricos foram correlacionados entre eles e para p<= 0,05 foi obtido entre torque de inserção e ISQ mesio-distal (0.131), entre o ISQ vestibulo-lingual e os valores de pixels (0.156) e ISQ mesio-distal e IPMI esquerdo (0.149) e ISQ mesio-distal e IPMS esquerdo (0.145). Existe correlação entre a TCFC, o torque de inserção e a RFA na avaliação da qualidade óssea. É possível utilizar, pré-cirurgicamente, os exames de TCFC para avaliar a qualidade e quantidade óssea, tendo em vista as correlações obtidas neste estudo.

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Los avances en la era endovascular han causado una revolución en el abordaje de la estenosis carotidea. La irrupción del abordaje transfemoral y transcervical ha hecho que la comunidad científica nos replanteemos las indicaciones terapeúticas en pacientes con estenosis carotidea sintomática o asintomática. Aunque los resultados del abordaje transfemoral mejoraron con la introducción de los sistemas de neuroprotección, un abundante número de estudios randomizados han sido dirigidos para comparar stent transfemoral frente a la endarterectomia. Endarterectomia frente a angioplastia en pacientes con estenosis severa sintomatica(EVA-3S), angioplastia con stent y neuroprotección frente a endarterectomia (SPACE), Angioplastia carotidea y vertebral (CAVATAS), revascularización carotidea mediante stent versus endarterectomia (CREST) estudio internacional carotideo (ICSS) todos fallaron en demostrar una ventaja global del stent transfemoral frente a la endarterectomia. El abordaje transcervical surge por tanto como opción segura de tratamiento, con buenos resultados clínicos iniciales, eliminando así algunas de las complicaciones del acceso transfemoral. Existe hasta la fecha una falta de estudios comparativos de morbimortalidad entre las tres opciones terapeúticas. Además, dado el elevado número de pacientes candidatos a ellos, es necesario una análisis de resultados y supervivencia de los mismos, asi como un análisis de costes relativos y coste-efectividad que podría tener importantes implicaciones en las políticas de salud y en las guias de tratamiento...

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Introducción: el triatlón es un deporte de resistencia e individual que está formado por tres disciplinas diferentes: natación, ciclismo y carrera a pie. El objetivo del estudio es describir las características antropométricas en triatletas varones universitarios, además de analizar y describir la composición corporal y el somatotipo de dichos triatletas. Metodología: estudio observacional y descriptivo de las características antropométricas, la composición corporal y el somatotipo de 39 triatletas varones universitarios entre 24 ± 4,5 años, participantes en el campeonato de España universitario de triatlón, modalidad sprint (Alicante 2010), procedentes de diferentes universidades españolas. Según la técnicas de medición antropométrica adoptadas por la International Society for the Advancement of Kinanthropometry (ISAK) y el Grupo Español de Cineantropometría (GREC) por un evaluador acreditado ISAK de nivel II. Resultados: nos encontramos con deportistas de talla baja, en los que destacan valores inferiores a lo normal en los pliegues cutáneos subescapular, supraespinal, tricipital y bicipital, un porcentaje de masa muscular (45,27 ± 3,29%), de masa grasa (10,22 ± 2,92%) y de masa ósea (16,65 ± 1,34%) y un somatotipo en el que predomina la mesomorfia. Discusión: los triatletas y corredores presentan más baja talla que los ciclistas y nadadores. Los triatletas y ciclistas muestran un peso similar, siendo menor que el de los nadadores de fondo y mayor que el de los corredores de 10 km. Los pliegues cutáneos cresta ilíaca, abdominal y muslo frontal de los ciclistas son inferiores al de los triatletas. El porcentaje de masa grasa de triatletas corredores y nadadores son similares; sin embargo, el de la masa muscular de los triatletas suele ser inferior al de los ciclistas pero similar a las demás modalidades. El somatotipo del triatleta se asemeja al del ciclista (mesomorfo). El del corredor es mesomorfo-ectomorfo y el del nadador puede oscilar de mesomorfo a ectomorfo.

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This layer is a georeferenced raster image of the historic, topographic paper map entitled: Chicago and vicinity, Ill.-Ind. : sheet no. 3 of 3 (Blue Island), 1953, mapped, edited, and published by the Geological Survey. It was published in 1957. Scale 1:24,000. The source map was compiled from 1:24,000 scale maps of Calumet Lake, Blue Island, Palos Park, Sag Bridge, Mokena, Tinley Park, Harvey, and Calumet City 1953 7.5 minute quadrangles. Hydrography from U.S. Lake Survey Chart 755 (1:15,000). This layer is image 3 of 3 total images of the three sheet source map. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Illinois East State Plane Coordinate System NAD27 (in Feet) (Fipszone 1201). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This is a typical topographic map portraying both natural and manmade features. It shows and names works of nature, such as mountains, valleys, lakes, rivers, vegetation, etc. It also identify the principal works of humans, such as roads, railroads, boundaries, transmission lines, major buildings, etc. Relief is shown with standard contour intervals of 5 feet. Depths shown by isolines and soundings. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

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Distinct glial cell types of the vertebrate peripheral nervous system (PNS) are derived from the neural crest. Here we show that the expression of the Ets domain transcription factor Erm distinguishes satellite glia from Schwann cells beginning early in rat PNS development. In developing dorsal root ganglia (DRG), Erm is present both in presumptive satellite glia and in neurons. In contrast, Erm is not detectable at any developmental stage in Schwann cells in peripheral nerves. In addition, Erm is downregulated in DRG-derived glia adopting Schwann cell traits in culture. Thus, Erm is the first described transcription factor expressed in satellite glia but not in Schwann cells. In culture, the Neuregulin1 (NRG1) isoform GGF2 maintains Erm expression in presumptive satellite cells and reinduces Erm expression in DRG-derived glia but not in Schwann cells from sciatic nerve. These data demonstrate that there are intrinsic differences between these glial subtypes in their response to NRG1 signaling. In neural crest cultures, Erm-positive progenitor cells give rise to two distinct glial subtypes: Erm-positive, Oct-6-negative satellite glia in response to GGF2, and Erm-negative, Oct-6-positive Schwann cells in the presence of serum and the adenylate cyclase activator forskolin. Thus, Erm-positive neural crest-derived progenitor cells and presumptive satellite glia are able to acquire Schwann cell features. Given the in vivo expression of Erm in peripheral ganglia, we suggest that ganglionic Erm-positive cells may be precursors of Schwann cells.

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During ODP Leg 193, 4 sites were drilled in the active PACMANUS hydrothermal field on the crest of the felsic Pual Ridge to examine the vertical and lateral variations in mineralization and alteration patterns. We present new data on clay mineral assemblages, clay and whole rock chemistry and clay mineral strontium and oxygen isotopic compositions of altered rocks from a site of diffuse low-temperature venting (Snowcap, Site 1188) and a site of high-temperature venting (Roman Ruins, Site 1189) in order to investigate the water-rock reactions and associated elemental exchanges. The volcanic succession at Snowcap has been hydrothermally altered, producing five alteration zones: (1) chlorite+/-illite-cristobalite-plagioclase alteration apparently overprinted locally by pyrophyllite bleaching at temperatures of 260-310°C; (2) chlorite+/-mixed-layer clay alteration at temperatures of 230°C; (3) chlorite and illite alteration; (4) illite and chlorite+/-illite mixed-layer alteration at temperatures of 250-260°C; and (5) illite+/-chlorite alteration at 290-300°C. Felsic rocks recovered from two holes (1189A and 1189B) at Roman Ruins, although very close together, show differing alteration features. Hole 1189A is characterized by a uniform chlorite-illite alteration formed at ~250°C, overprinted by quartz veining at 350°C. In contrast, four alteration zones occur in Hole 1189B: (1) illite+/-chlorite alteration formed at ~300°C; (2) chlorite+/-illite alteration at 235°C; (3) chlorite+/-illite and mixed layer clay alteration; and (4) chlorite+/-illite alteration at 220°C. Mass balance calculations indicate that the chloritization, illitization and bleaching (silica-pyrophyllite assemblages) alteration stages are accompanied by different chemical changes relative to a calculated pristine precursor lava. The element Cr appears to have a general enrichment in the altered samples from PACMANUS. The clay concentrate data show that Cr and Cu are predominantly present in the pyrophyllites. Illite shows a significant enrichment for Cs and Cu relative to the bulk altered samples. Considerations of mineral stability allow us to place some constraints on fluid chemistry. Hydrothermal fluid pH for the chloritization and illitization was neutral to slightly acidic and relatively acidic for the pyrophyllite alteration. In general the fluids, especially from Roman Ruins and at intermediate depths below Snowcap, show only a small proportion of seawater mixing (<10%). Fluids in shallow and deep parts of the Snowcap holes, in contrast, show stronger seawater influence.

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Expedition 302 of the Integrated Ocean Drilling Program (IODP), also known as the Arctic Coring Expedition (ACEX), successfully penetrated a sequence of Cenozoic sediments draping the crest of the Lomonosov Ridge in the central Arctic Ocean. The cumulative sedimentary record spans the last 57 m.y. and was recovered from three sites located within 15 km of each other. Merging the recovered cores onto a common depth scale that accurately reflects their stratigraphic placement below the seafloor is a fundamental step toward interpreting this unique sedimentary record. However, the lack of overlapping recovery in adjacent holes and intervals of high core disturbance complicated traditional methods of stratigraphic correlation. Here we present a revised composite depth scale for the ACEX sediments, generated in part by performing a regional stratigraphic correlation with sediments recovered from previous expeditions to the Lomonosov Ridge. The revised depth scale also reassesses the offsets for cores in the upper 55 meters below seafloor, where no overlapping recovery was acquired, and proposes modifications to these depths.

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Uniquely in the Southern Hemisphere the New Zealand micro-continent spans the interface between a subtropical gyre and the Subantarctic Circumpolar Current. Its 20° latitudinal extent includes a complex of submerged plateaux, ridges, saddles and basins which, in the present interglacial, are partial barriers to circulation and steer the Subtropical (STF) and Subantarctic (SAF) fronts. This configuration offers a singular opportunity to assess the influence of bottom topography on oceanic circulation through Pleistocene glacial - interglacial (G/I) cycles, its effect on the location and strength of the fronts, and its ability to generate significant differences in mixed layer thermal history over short distances. For this study we use new planktic foraminiferal based sea-surface temperature (SST) estimates spanning the past 1 million years from a latitudinal transect of four deep ocean drilling sites. We conclude that: 1. the effect of the New Zealand landmass was to deflect the water masses south around the bathymetric impediments; 2. the effect of a shallow submerged ridge on the down-current side (Chatham Rise), was to dynamically trap the STF along its crest, in stark contrast to the usual glacial-interglacial (G-I) meridional migration that occurs in the open ocean; 3. the effect of more deeply submerged, downstream plateaux (Campbell, Bounty) was to dynamically trap the SAF along its steep southeastern margin; 4. the effects of saddles across the submarine plateaux was to facilitate the development of jets of subtropical and subantarctic surface water through the fronts, forming localized downstream gyres or eddies during different phases in the G-I climate cycles; 5. the deep Pukaki Saddle across the Campbell-Bounty Plateaux guided a branch of the SAF to flow northwards during each glacial, to form a strong gyre of circumpolar surface water in the Bounty Trough, especially during the mid-Pleistocene Climate Transition (MIS 22-16) when exceptionally high SST gradients existed across the STF; 6. the shallower Mernoo Saddle, at the western end of the Chatham Rise, provided a conduit for subtropical water to jet southwards across the STF in the warmest interglacial peaks (MIS 11, 5.5) and for subantarctic water to flow northwards during glacials; 7. although subtropical or subantarctic drivers can prevail at a particular phase of a G-I cycles, it appears that the Antarctic Circumpolar Current is the main influence on the regional hydrography. Thus complex submarine topography can affect distinct differences in the climate records over short distances with implications for using such records in interpreting global or regional trends. Conversely, the local topography can amplify the paleoclimate record in different ways in different places, thus enhancing its value for the study of more minor paleoceanographic influences that elsewhere are more difficult to detect. Such sites include DSDP 594, which like some other Southern Ocean sites, has the typical late Pleistocene asymmetrical saw-tooth G-I climate pattern transformed to a gap-tooth pattern of quasi-symmetrical interglacial spikes that interrupt extended periods of minimum glacial temperatures.

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During Leg 65, four sites were drilled near the mouth of the Gulf of California where high sedimentation rates made it possible to sample young oceanic crust near the ridge crest. The oldest sediments cored were upper Pliocene siltstones (Site 483); the samples at the other sites (482, 484, and 485) were all Quaternary in age. A series of 80 sediment samples, most of them hemipelagic clays, were examined by semiquantitative X-ray diffraction and Carbonate Bomb techniques to determine their mineralogy and carbonate contents. The results of this study may be used to determine their provenance and diagenesis.

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Strontium concentrations and 87Sr/86Sr values were measured on pore-water and sedimentary carbonate samples from sediments recovered at Sites 1049-1053 on the Blake Spur during Ocean Drilling Program Leg 171B. These sites form a 40-km-long depth transect extending along the crest of the Blake Spur from near the upper edge of the Blake Escarpment (a steep cliff composed of Mesozoic carbonates) westward toward the interior of the Blake-Bahama Platform. Although these sites were selected for paleoceanographic purposes, they also form a hydrologic transect across the upper eastern flank of the Blake-Bahama Platform. Here, we use pore-water strontium concentrations and isotopes as a proxy to define patterns of fluid movement through the flanks of this platform. Pore-water strontium concentration increases with depth at all sites implying that strontium has been added during sediment burial and diagenesis. The isotopic values decrease from seawater-like values in the shallow samples (~0.70913) to values as low as 0.707342 in one of the deepest samples (~625 meters below seafloor). The change in pore-water strontium isotopic values is independent of the strontium isotopic compositions predicted from the host sediment age and measured on bulk carbonate in some samples. In most cases the difference between predicted sediment strontium isotopic composition and measured value is less than ±2 about the mean of the measured strontium value. Both the increase in concentration and the decrease in the strontium isotope values with increasing depth indicate that strontium was expelled from older carbonates. The strontium concentration and isotope profiles vary between sites according to their proximity to the Blake-Bahama Platform edge. Profiles from Site 1049 (nearest the platform edge) show the greatest amount of mixing with modern seawater, whereas the site most distal to the platform edge (Site 1052) shows the most significant influence of older, deeper carbonates on the pore-water strontium isotopic composition.