1,690 research outputs found

    Direct microvascular monitoring of a free autologous jejunal flap using microendoscopy: a case report

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    BACKGROUND: Early identification of flap failure is an indispensable prerequisite for flap salvage. Although many technical developments of free flap monitoring have now reached clinical application, very few are considered to be reliable and non-invasive for early recognition of flap failure. CASE PRESENTATION: We used microendoscopic technique for microvascular monitoring of free autologous jejunal flap by the direct visualisation of the flow of erythrocytes through the capillary vasculature on both the mucosal and serosal surfaces. Blood flow was seen to be pulsatile, with individual erythrocytes visible in the capillaries. The best view was obtained when the scope was focussed directly on the capillary rather than the graft surface. The view of the unstained mucosal surface was bland apart from the fine capillary loops which were seen to fill with each pulsatile event. The microendoscopic examination of the serosal surface revealed much larger calibre vessels with obvious blood flow. CONCLUSION: The microendoscopic monitoring technique is simple and safe with direct visualisation of blood flow. The technique may also be useful for the monitoring of other free bowel transplants

    The Jurassic–Cretaceous depositional and tectonic evolution of the southernwestern margin of the Neotethys Ocean, Northern Oman and United Arab Emirates

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    The concept that the autochthonous, parautochthonous and allochthonous Permian–Cretaceous sequences in the United Arab Emirates (UAE) and Oman record the transition from platform, slope to basin sedimentation within the southern part of Neotethys has been fundamental to the interpretation of the geological history of the region. The results of a major geological mapping programme of the UAE, carried out by the British Geological Survey for the Federal Government of the UAE, coupled with the detailed examination of key sections within northern Oman has led to a re-evaluation of the geological evolution of this region. This detailed study has led to a greater appreciation of the sedimentology and depositional setting of the sediments laid down along the northeastern Arabian continental margin during the Jurassic to Cretaceous, allowing a more refined model of Neotethys Ocean basin evolution to be established. The model charts the progressive breakup of the Arabian continental margin and closure of Neotethys during the mid to late Cretaceous and is divided into three main stages: Stage 1—Initial rifting and formation of the Neotethys Ocean, followed by a prolonged period of stable, passive margin sedimentation which extended from the Permian to Late Jurassic times; Stage 2—Uplift and erosion of the shelf margin during the Late Jurassic to Early Cretaceous, coincident with increased carbonate-clastic sedimentation in the outer ramp, distal slope and basinal areas; Stage 3—Increased instability during the Late Cretaceous leading to the breakup of the platform margin and foreland basin sedimentation accompanying the obduction of the Oman-UAE ophiolite. Data obtained for the upper part of the platform and platform margin to slope successions has revealed that the topography of the “shelf”-slope-basinal margin was more subdued than previously thought, with this more gentle ramp margin morphology persisting until early to mid-Cretaceous times when the platform margin started to become unstable during ophiolite obduction. The thrust-repeated allochthonous sedimentary rocks of the Hamrat Duru Group were deposited on the outer platform margin/lower slope rise to basinal plain of this basin margin and includes the dismembered remains of two turbidite fan systems which fed carbonate-rich detritus into deeper parts of the ocean. A re-evaluation of the chert-rich sequences, previously equated with deposition on the abyssal plain of Neotethys, has led to the conclusion that they may record sedimentation at a much shallower level within a starved ocean basin, possibly in a mid-ramp (above storm wave base) to outer ramp setting. A marked change in basin dynamics occurred during the mid-Cretaceous leading to the development of a shallow ramp basin margin in Oman with terrestrial to shallow marine sedimentary rocks interdigitating with red siliceous mudstones. By contrast, the contemporaneous succession in the Dibba Zone of the UAE indicates considerable instability on a steep shelf break. This instability is recorded by the presence of several major olistostrome deposits within the Aruma Group of the UAE which are thought to have been generated in advance of the rapidly obducting Oman-UAE ophiolite

    Impact of disease severity on outcome of antiviral therapy for chronic hepatitis C: Lessons from the HALT-C trial

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    In patients with chronic hepatitis C, advanced fibrosis and cirrhosis are associated with lower rates of sustained virologic response (SVR) to interferon (IFN)-based therapy. In this study, we assessed virologic response to retreatment with peginterferon alfa-2a and ribavirin (RBV), as a function of the baseline fibrosis score (Ishak staging) and platelet count, in 1,046 patients enrolled in the Hepatitis C Antiviral Long-term Treatment against Cirrhosis (HALT-C) Trial. All patients had failed prior treatment with IFN or peginterferon ± RBV and had Ishak fibrosis scores ≥ 3. Four groups of patients with increasingly severe liver disease were compared: (A) bridging fibrosis (Ishak 3 and 4) with platelet counts >125,000/mm 3 (n = 559); (B) bridging fibrosis with platelet counts ≤125,000/mm 3 (n = 96); (C) cirrhosis (Ishak 5 and 6) with platelet counts >125,000/mm 3 (n = 198); and (D) cirrhosis with platelet counts ≤125,000/mm 3 (n = 193). SVR rates were 23%, 17%, 10%, and 9% in groups A, B, C, and D, respectively ( P < .0001 for trend). Reduction in SVR as a function of increasingly severe disease was independent of age, percent African American, HCV genotype, HCV level, and type of prior therapy. Dose reduction lowered SVR frequencies, but to a lesser extent than disease severity. By logistic regression, cirrhosis ( P < .0001) was the major determinant that impaired virologic response, independent of dose reduction or platelet count. In conclusion , disease severity is a major independent determinant of rate of SVR in patients with advanced chronic hepatitis C. New strategies are needed to optimize antiviral therapy in these “difficult-to-cure” patients. (H EPATOLOGY 2006;44:1675–1684.)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55880/1/21440_ftp.pd

    Theory of mind in utterance interpretation: the case from clinical pragmatics

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    The cognitive basis of utterance interpretation is an area that continues to provoke intense theoretical debate among pragmatists. That utterance interpretation involves some type of mind-reading or theory of mind (ToM) is indisputable. However, theorists are divided on the exact nature of this ToM-based mechanism. In this paper, it is argued that the only type of ToM-based mechanism that can adequately represent the cognitive basis of utterance interpretation is one which reflects the rational, intentional, holistic character of interpretation. Such a ToM-based mechanism is supported on conceptual and empirical grounds. Empirical support for this view derives from the study of children and adults with pragmatic disorders. Specifically, three types of clinical case are considered. In the first case, evidence is advanced which indicates that individuals with pragmatic disorders exhibit deficits in reasoning and the use of inferences. These deficits compromise the ability of children and adults with pragmatic disorders to comply with the rational dimension of utterance interpretation

    The metamorphism and exhumation of the Himalayan metamorphic core, eastern Garhwal region, India

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    [1] Geothermobarometric together with micro- and macro-structural data indicate ductile flow in the metamorphic core of the Himalaya in the Garhwal region of India. Peak metamorphic pressure and temperature increase dramatically across the Main Central Thrust (MCT) from ~5 kbar and ~550°C in the Lesser Himalayan Crystalline Sequence (LHCS) to ~14 kbar and ~850°C at ~3 km above the MCT in the Greater Himalayan Sequence (GHS). Pressures within the GHS then decrease upsection to ~8 kbar while temperatures remain nearly constant at ~850°C up to the structurally overlying South Tibetan Detachment (STD). The GHS exhibits sheath fold geometries are indicative of high degrees of ductile flow. Overprinting ductile structures are two populations of extensional conjugate fractures and normal faults oriented both parallel and perpendicular to the orogen. These fractures crosscut major tectonic boundaries in the region such as the MCT and STD, and are found throughout the LHCS, GHS, and Tethyan Sedimentary Sequence (TSS). The thermobarometric and metamorphic observations are consistent with a form of channel flow. However, channel flow does not account for exhumational structures that formed above the brittle-ductile transition. To explain all of the features seen in the metamorphic core of the Garhwal region of the Himalaya, both the theories of channel flow and critical taper must be taken into account. Channel flow can explain the exhumation of the GHS from the middle crust to the brittle-ductile transition. The most recent extensional deformation is consistent with a supercritical wedge

    Statistical Power of Model Selection Strategies for Genome-Wide Association Studies

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    Genome-wide association studies (GWAS) aim to identify genetic variants related to diseases by examining the associations between phenotypes and hundreds of thousands of genotyped markers. Because many genes are potentially involved in common diseases and a large number of markers are analyzed, it is crucial to devise an effective strategy to identify truly associated variants that have individual and/or interactive effects, while controlling false positives at the desired level. Although a number of model selection methods have been proposed in the literature, including marginal search, exhaustive search, and forward search, their relative performance has only been evaluated through limited simulations due to the lack of an analytical approach to calculating the power of these methods. This article develops a novel statistical approach for power calculation, derives accurate formulas for the power of different model selection strategies, and then uses the formulas to evaluate and compare these strategies in genetic model spaces. In contrast to previous studies, our theoretical framework allows for random genotypes, correlations among test statistics, and a false-positive control based on GWAS practice. After the accuracy of our analytical results is validated through simulations, they are utilized to systematically evaluate and compare the performance of these strategies in a wide class of genetic models. For a specific genetic model, our results clearly reveal how different factors, such as effect size, allele frequency, and interaction, jointly affect the statistical power of each strategy. An example is provided for the application of our approach to empirical research. The statistical approach used in our derivations is general and can be employed to address the model selection problems in other random predictor settings. We have developed an R package markerSearchPower to implement our formulas, which can be downloaded from the Comprehensive R Archive Network (CRAN) or http://bioinformatics.med.yale.edu/group/

    The Stereodivergent Formation of 2,6-cis and 2,6-trans-Tetrahydropyrans: Experimental and Computational Investigation of the Mechanism of a Thioester Oxy-Michael Cyclization

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    The origins of the stereodivergence in the thioester oxy-Michael cyclization for the formation of 4-hydroxy-2,6-cis- or 2,6-trans-substituted tetrahydropyran rings under different conditions was investigated both computationally and experimentally. Synthetic studies showed that the 4-hydroxyl group was essential for stereodivergence. When the 4-hydroxyl group was present, TBAF-mediated conditions gave the 2,6-trans-tetrahydropyran and trifluoroacetic acid-mediated conditions gave the 2,6-cis-tetrahydropyran. This stereodivergence vanished when the hydroxyl group was removed or protected. Computational studies revealed that: (i) the trifluoroacetic acid catalysed formation of 2,6-cis-tetrahydropyrans was mediated by a trifluoroacetate-hydroxonium bridge and proceeded via a chair-like transition state; (ii) the TBAF-mediated formation of 2,6-trans-tetrahydropyrans proceeded via a boat-like transition state, where the 4-hydroxyl group formed a crucial hydrogen bond to the cyclizing alkoxide; (iii) both reactions are under kinetic control. The utility of this stereodivergent approach for the formation of 4-hydroxy-2,6-substituted tetrahydropyran rings has been demonstrated by the total syntheses of the anti-osteoporotic natural products diospongin A and

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
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