169 research outputs found

    Allylsulfones through Palladium-Catalyzed Allylic C−H Sulfonylation of Terminal Alkenes

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    Two previously unknown protocols for Pd-catalyzed allylic C-H sulfonylation of terminal alkenes have been developed. While the former consists of a direct Pd(II)-catalyzed oxidative C-H allylic sulfonylation in the presence of sulfinate anions, the latter involves a sequential one-pot Pd(II)-catalyzed C-H allylic acetoxylation followed by a Pd(0)-catalyzed sulfonylation. The scope of both protocols was studied on 25 examples

    Concentração de ferro anormalmente aumentada nos núcleos da base na síndrome de Shy-Drager

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    Report of an early case of Shy-Drager syndrome in a 67 year-old woman patient. Autonomic failure was diagnosed by functional evaluation as well as laboratory tests. MR imaging disclosed a prominent putamina hypodensity in T2-weighted images at high field strength due to iron increased depositing in this basal ganglia. MR imaging evidences confirm Shy-Drager syndrome diagnosis, and contributes for differential diagnosis of idiopathic hypotension (pure autonomic failure) in special in SDS early cases.É relatado o caso de unm paciente de 67 anos de idade com quadro inicial da síndrome de Shy-Drager. O diagnóstico foi possível por provas funcionais autonômicas e exames laboratoriais. A ressonância magnética cerebral (contraste baseado na densidade de prótons e em T2) objetivou proeminente hipodensidade putaminal em T2, secundária ao aumento do depósito do ferro nesta região. Esse achado da RM confirma o diagnóstico da síndrome de Shy-Drager e permite diferenciá-la da hipotensão ortostática idiopática, particularmente na fase de início da SSD quando os sinais de comprometimento do SNC são discretos ou estão ausentes.34234

    Exploring the isopycnal mixing and helium–heat paradoxes in a suite of Earth system models

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    This paper uses a suite of Earth system models which simulate the distribution of He isotopes and radiocarbon to examine two paradoxes in Earth science, each of which results from an inconsistency between theoretically motivated global energy balances and direct observations. The helium–heat paradox refers to the fact that helium emissions to the deep ocean are far lower than would be expected given the rate of geothermal heating, since both are thought to be the result of radioactive decay in Earth's interior. The isopycnal mixing paradox comes from the fact that many theoretical parameterizations of the isopycnal mixing coefficient ARedi that link it to baroclinic instability project it to be small (of order a few hundred m² s⁻¹) in the ocean interior away from boundary currents. However, direct observations using tracers and floats (largely in the upper ocean) suggest that values of this coefficient are an order of magnitude higher. Helium isotopes equilibrate rapidly with the atmosphere and thus exhibit large gradients along isopycnals while radiocarbon equilibrates slowly and thus exhibits smaller gradients along isopycnals. Thus it might be thought that resolving the isopycnal mixing paradox in favor of the higher observational estimates of ARedi might also solve the helium paradox, by increasing the transport of mantle helium to the surface more than it would radiocarbon. In this paper we show that this is not the case. In a suite of models with different spatially constant and spatially varying values of ARedi the distribution of radiocarbon and helium isotopes is sensitive to the value of ARedi. However, away from strong helium sources in the southeastern Pacific, the relationship between the two is not sensitive, indicating that large-scale advection is the limiting process for removing helium and radiocarbon from the deep ocean. The helium isotopes, in turn, suggest a higher value of ARedi below the thermocline than is seen in theoretical parameterizations based on baroclinic growth rates. We argue that a key part of resolving the isopycnal mixing paradox is to abandon the idea that ARedi has a direct relationship to local baroclinic instability and to the so-called "thickness" mixing coefficient AGM

    Responsive polysaccharide-grafted surfaces for biotribological applications

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    The elucidation of biolubrication mechanisms and the design of artificial biotribological contacts requires the development of model surfaces that can help to tease out the cues that govern friction in biological systems. Polysaccharides provide an interesting option as a biotribological mimic due to their similarity with the glycosylated molecules present at biointerfaces. Here, pectin was successfully covalently grafted at its reducing end to a polydimethylsiloxane (PDMS) surface via a reductive amination reaction. This method enabled the formation of a wear resistant pectin layer that provided enhanced boundary lubrication compared to adsorbed pectin. Pectins with different degrees of methylesterification and blockiness were exposed to salt solutions of varying ionic strength and displayed responsiveness to solvent conditions. Exposure of the grafted pectin layers to solutions of between 1 and 200 mM NaCl resulted in a decrease in boundary friction and an increase in the hydration and swelling of the pectin layer to varying degrees depending on the charge density of the pectin, showing the potential to tune the conformation and friction of the layer using the pectin architecture and environmental cues. The robust and responsive nature of these new pectin grafted surfaces makes them an effective mimic of biotribological interfaces and provides a powerful tool to study the intricate mechanisms involved in the biolubrication phenomenon

    The GCC repeat length in the 5'UTR of MRP1 gene is polymorphic: a functional characterization of its relevance for cystic fibrosis

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    BACKGROUND: Among the members of the ATP binding cassette transporter superfamily, MRPs share the closest homology with the CFTR protein, which is defective in CF disease. MRP1 has been proposed as a potential modifier gene and/or as novel target for pharmacotherapy of CF to explain the clinical benefits observed in some CF patients treated with the macrolide AZM. The 5'UTR of the MRP1 gene contains a GCC triplet repeat that could represent a polymorphic site and affect the activity of the promoter. METHODS: The MRP1 5' flanking region was amplified by PCR from 36 CF patients and 100 non-CF subjects and the number of GCC triplets of each allele was determined by sequence and electrophoretic analysis. We performed gene reporter studies in CF airway epithelial cells 16HBE14o-AS3, in basal conditions and in the presence of AZM. RESULTS: We found that the GCC repeat is polymorphic, ranging from 7 to 14 triplets either in CF or in non-CF subjects. Our data are preliminary and have to be confirmed on a larger population of CF subjects. The transcriptional activity of the proximal MRP1 5' regulatory region revealed no statistically significant correlations between the number of repeats and treatment with AZM. CONCLUSION: We identified a novel polymorphism in the 5'UTR of MRP1 gene that provides multiple alleles in a gene relevant for multidrug resistance as well as for CF, determining that this region is transcriptionally active and that this activity does not appear to be influenced by AZM treatment

    Early bronchopulmonary involvement in Crohn disease: a case report

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    BACKGROUND: Bronchopulmonary manifestations of Crohn disease have been rarely described in children, including both subclinical pulmonary involvement and severe lung disease. CASE PRESENTATION: A 6.5-year-old girl is described with early recurrent bronchopulmonary symptoms both at presentation and in the quiescent phase of Crohn disease. Pulmonary function tests (lung volumes and flows, bronchial reactivity and carbon monoxide diffusing capacity) were normal. Bronchoalveolar cytology showed increased (30%) lymphocyte counts and bronchial biopsy revealed thickening of basal membrane and active chronic inflammation. CONCLUSIONS: Clinical and histological findings in our young patient suggest involvement of both distal and central airways in an early phase of lung disease. The pathogenesis of Crohn disease-associated lung disorders is discussed with reference to the available literature. A low threshold for pulmonary evaluation seems to be advisable in all children with CD
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