4,598 research outputs found

    A lactate-derived chiral aldehyde for determining the enantiopurity of enantioenriched primary amines

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    In this paper we describe the use of a chiral aldehyde derived from lactate esters for determining the enantiopurity of primary amines, via the formation of diastereomeric imines. The method was shown to be suitable for reproducibly determining the enantiopurity of a diverse set of chiral amines. Both enantiomers of the aldehyde can be prepared in two steps from commercially available materials

    Expanding the scope of N → S acyl transfer in native peptide sequences

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    Understanding the factors that influence N → S acyl transfer in native peptide sequences, and discovery of new reagents that facilitate it, will be key to expanding its scope and applicability. Here, through a study of short model peptides in thioester formation and cyclisation reactions, we demonstrate that a wider variety of Xaa-Cys motifs than originally envisaged are capable of undergoing efficient N → S acyl transfer. We present data for the relative rates of thioester formation and cyclisation for a representative set of amino acids, and show how this expanded scope can be applied to the production of the natural protease inhibitor Sunflower Trypsin Inhibitor-1 (SFTI-1)

    Tailoring Gold Nanoparticle Characteristics and the Impact on Aqueous-Phase Oxidation of Glycerol

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    Poly(vinyl alcohol) (PVA)-stabilized Au nanoparticles (NPs) were synthesized by colloidal methods in which temperature variations (−75 to 75 °C) and mixed H2O/EtOH solvent ratios (0, 50, and 100 vol/vol) were used. The resulting Au NPs were immobilized on TiO2 (P25), and their catalytic performance was investigated for the liquid phase oxidation of glycerol. For each unique solvent system, there was a systematic increase in the average Au particle diameter as the temperature of the colloidal preparation increased. Generation of the Au NPs in H2O at 1 °C resulted in a high observed activity compared with current Au/TiO2 catalysts (turnover frequency = 915 h–1). Interestingly, Au catalysts with similar average particle sizes but prepared under different conditions had contrasting catalytic performance. For the most active catalyst, aberration-corrected high angle annular dark field scanning transmission electron microscopy analysis identified the presence of isolated Au clusters (from 1 to 5 atoms) for the first time using a modified colloidal method, which was supported by experimental and computational CO adsorption studies. It is proposed that the variations in the populations of these species, in combination with other solvent/PVA effects, is responsible for the contrasting catalytic properties

    Synthesis of Boronocysteine

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    Herein we report the first synthesis of protected boronocysteine. The target compound was prepared via copper-catalysed diastereoselective nucleophilic borylation of a sulfinimine. After deprotection to give the amine as the hydrochloride salt, four boronocysteine amide derivatives were prepared through reaction with a variety of different active acylating agents

    A distinct plasmablast and naive B-cell phenotype in primary immune thrombocytopenia

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    Obtained from the Haematologica Journal website http://www.haematologica.org/content/101/6/698.full.pdf+html Material published in Haematologica is covered by copyright. All rights reserved to Ferrata Storti Foundation. Copies of articles are allowed for personal or internal use. A permission in writing by the publisher is requested for any other use.Primary funding for this study was from GSK. SMF was funded by a Translational Medicine and Therapeutics PhD studentship jointly funded by the Wellcome Trust and GSK. The UK ITP Registry (www.ukitpregistry.com) is supported through unrestricted educational grants from GSK and Amgen

    Mevalonate kinase deficiencies: from mevalonic aciduria to hyperimmunoglobulinemia D syndrome

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    Mevalonic aciduria (MVA) and hyperimmunoglobulinemia D syndrome (HIDS) represent the two ends of a clinical spectrum of disease caused by deficiency of mevalonate kinase (MVK), the first committed enzyme of cholesterol biosynthesis. At least 30 patients with MVA and 180 patients with HIDS have been reported worldwide. MVA is characterized by psychomotor retardation, failure to thrive, progressive cerebellar ataxia, dysmorphic features, progressive visual impairment and recurrent febrile crises. The febrile episodes are commonly accompanied by hepatosplenomegaly, lymphadenopathy, abdominal symptoms, arthralgia and skin rashes. Life expectancy is often compromised. In HIDS, only febrile attacks are present, but a subgroup of patients may also develop neurological abnormalities of varying degree such as mental retardation, ataxia, ocular symptoms and epilepsy. A reduced activity of MVK and pathogenic mutations in the MVK gene have been demonstrated as the common genetic basis in both disorders. In MVA, the diagnosis is established by detection of highly elevated levels of mevalonic acid excreted in urine. Increased levels of immunoglobulin D (IgD) and, in most patients of immunoglobulin A (IgA), in combination with enhanced excretion of mevalonic acid provide strong evidence for HIDS. The diagnosis is confirmed by low activity of mevalonate kinase or by demonstration of disease-causing mutations. Genetic counseling should be offered to families at risk. There is no established successful treatment for MVA. Simvastatin, an inhibitor of HMG-CoA reductase, and anakinra have been shown to have beneficial effect in HIDS

    Purtscher-like retinopathy following valsalva maneuver effect: case report

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    <p>Abstract</p> <p>Introduction</p> <p>Purtscher's retinopathy is a rare condition that is noted in cases related to various types of trauma. The characteristic finding in the fundus is the presence of multiple Purtscher flecken. Purtscher-like retinopathy has a similar presentation in the fundus, but without an association with trauma.</p> <p>Case presentation</p> <p>A 43-year old Malay man presented with a sudden onset of central foggy vision in the left eye after holding his breath for two minutes while catching a falling object. It was not associated with floaters, flashes of light, or head trauma. His vision in the right eye was 6/6, and in his left eye it was finger counting. He had bilateral temporal sub-conjunctival hemorrhages. An examination of his left fundus revealed multiple white cotton wool spots and dot-blot retinal hemorrhages with diffuse retinal edema at the posterior pole. His right fundus was noted to have only mild temporal peri-papillary edema associated with a few dot-blot hemorrhages. Fundus fluorescein angiography showed good arterial perfusion and no evidence of leaking or neo-vascularization. A diagnosis of Purtscher-like retinopathy was made, and the patient was treated with indomethacin tablets for six weeks. At his six-week follow-up examination, his left eye visual acuity had improved to 6/12. His bilateral sub-conjunctival hemorrhage had resolved. His left fundus showed residual multiple cotton wool spots and reduced retinal edema.</p> <p>Conclusions</p> <p>Treatment with non-steroidal anti-inflammatory drugs seems to be effective in reducing edema in patients with Purtscher-like retinopathy.</p

    Compromized geranylgeranylation of RhoA and Rac1 in mevalonate kinase deficiency

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    Mevalonate kinase deficiency (MKD) is an autoinflammatory disorder caused by mutations in the MVK gene resulting in decreased activity of the enzyme mevalonate kinase (MK). Although MK is required for biosynthesis of all isoprenoids, in MKD, in particular, the timely synthesis of geranylgeranyl pyrophosphate appears to be compromised. Because small guanosine triphosphatases (GTPases) depend on geranylgeranylation for their proper signaling function, we studied the effect of MK deficiency on geranylgeranylation and activation of the two small GTPases, RhoA and Rac1. We demonstrate that both geranylgeranylation and activation of the two GTPases are more easily disturbed in MKD cells than in control cells when the flux though the isoprenoid biosynthesis pathway is suppressed by low concentrations of simvastatin. The limited capacity of geranylgeranylation in MKD cells readily leads to markedly increased levels of nonisoprenylated and activated GTPases, which will affect proper signaling by these GTPases

    An approximate model for cancellous bone screw fixation

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    This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2013 Taylor & Francis.This paper presents a finite element (FE) model to identify parameters that affect the performance of an improved cancellous bone screw fixation technique, and hence potentially improve fracture treatment. In cancellous bone of low apparent density, it can be difficult to achieve adequate screw fixation and hence provide stable fracture fixation that enables bone healing. Data from predictive FE models indicate that cements can have a significant potential to improve screw holding power in cancellous bone. These FE models are used to demonstrate the key parameters that determine pull-out strength in a variety of screw, bone and cement set-ups, and to compare the effectiveness of different configurations. The paper concludes that significant advantages, up to an order of magnitude, in screw pull-out strength in cancellous bone might be gained by the appropriate use of a currently approved calcium phosphate cement
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