390 research outputs found

    The healing mechanism for excited molecules near metallic surfaces

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    Radiation damage prevents the ability to obtain images from individual molecules. We suggest that this problem can be avoided for organic molecules by placing them in close proximity with a metallic surface. The molecules will then quickly dissipate any electronic excitation via their coupling to the metal surface. They may therefore be observed for a number of elastic scattering events that is sufficient to determine their structure.Comment: 4 pages, 4 figures. Added reference

    Isolation of white wine volatiles using different sample preparation methods

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    Three sample preparation methods for gas chromatographic analysis of white wine volatiles were tested. In order to find an adequate replacement for common liquidliquid extraction using 1,1,1-trichlorofluoromethan, headspace solid-phase microextraction (HS-SPME) and stir bar sorptive extraction (SBSE) were tested. SPME and SBSE sample preparations are characterized by rapid and easy handling, small sample size and the possibility of automation, but the recovery of aroma compounds is restricted because of the discrimination properties of the polymer phase. Unlike SPME, the results obtained by SBSE are more similar to those of liquid-liquid extraction.

    Study of phenolic and volatile composition of white wine during fermentation and a short time of storage

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    The phenolic composition including hydroxybenzoic acids, hydroxycinnamic acids and flavan-3-ols was identified and quantified in all studied samples by using a reversed-phase high-performance liquid chromatography (HPLC) system coupled with diode array detection. Gallic, protocatechuic, p-coumaric and vanillic acids were the major phenolic substances in grape juice, whereas caffeic acid was the most abundant phenolic acid in the wine after a short time of storage. For more reliable results, the antioxidant activity of grape juice and wine was measured by β-carotene bleaching (BCB) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging methods.The content changes of volatile compounds in the grape juice and wine were determined by using headspace solid phase microextraction (HS-SPME) coupled with gas chromatography (GC/FID and GC/MS). Hexanal, (E)-2-hexenal, 2-ethyl-1-hexanol, 1-hexanol, (Z)-neroloxide and linalool were the most representative compounds determined in grape juice, whereas ethyl esters of hexanoic, octanoic, decanoic and dodecanoic acids, hexyl acetate, isoamyl acetate, as well as isobutanol, isoamyl alcohol and 1-hexanol were identified as the main compounds.

    Co-localization of microstructural damage and excessive mechanical strain at aortic branches in angiotensin-II-infused mice

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    Animal models of aortic aneurysm and dissection can enhance our limited understanding of the etiology of these lethal conditions particularly because early-stage longitudinal data are scant in humans. Yet, the pathogenesis of often-studied mouse models and the potential contribution of aortic biomechanics therein remain elusive. In this work, we combined micro-CT and synchrotron-based imaging with computational biomechanics to estimate in vivo aortic strains in the abdominal aorta of angiotensin-II-infused ApoE-deficient mice, which were compared with mouse-specific aortic microstructural damage inferred from histopathology. Targeted histology showed that the 3D distribution of micro-CT contrast agent that had been injected in vivo co-localized with precursor vascular damage in the aortic wall at 3 days of hypertension, with damage predominantly near the ostia of the celiac and superior mesenteric arteries. Computations similarly revealed higher mechanical strain in branching relative to non-branching regions, thus resulting in a positive correlation between high strain and vascular damage in branching segments that included the celiac, superior mesenteric, and right renal arteries. These results suggest a mechanically driven initiation of damage at these locations, which was supported by 3D synchrotron imaging of load-induced ex vivo delaminations of angiotensin-II-infused suprarenal abdominal aortas. That is, the major intramural delamination plane in the ex vivo tested aortas was also near side branches and specifically around the celiac artery. Our findings thus support the hypothesis of an early mechanically mediated formation of microstructural defects at aortic branching sites that subsequently propagate into a macroscopic medial tear, giving rise to aortic dissection in angiotensin-II-infused mice

    Whole Exome Sequencing of Patients with Steroid-Resistant Nephrotic Syndrome

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    BACKGROUND AND OBJECTIVES: Steroid-resistant nephrotic syndrome overwhelmingly progresses to ESRD. More than 30 monogenic genes have been identified to cause steroid-resistant nephrotic syndrome. We previously detected causative mutations using targeted panel sequencing in 30% of patients with steroid-resistant nephrotic syndrome. Panel sequencing has a number of limitations when compared with whole exome sequencing. We employed whole exome sequencing to detect monogenic causes of steroid-resistant nephrotic syndrome in an international cohort of 300 families. DESIGN, SETTING, PARTIIPANTS AND MEASUREMENTS: Three hundred thirty-five individuals with steroid-resistant nephrotic syndrome from 300 families were recruited from April of 1998 to June of 2016. Age of onset was restricted to <25 years of age. Exome data were evaluated for 33 known monogenic steroid-resistant nephrotic syndrome genes. RESULTS: In 74 of 300 families (25%), we identified a causative mutation in one of 20 genes known to cause steroid-resistant nephrotic syndrome. In 11 families (3.7%), we detected a mutation in a gene that causes a phenocopy of steroid-resistant nephrotic syndrome. This is consistent with our previously published identification of mutations using a panel approach. We detected a causative mutation in a known steroid-resistant nephrotic syndrome gene in 38% of consanguineous families and in 13% of nonconsanguineous families, and 48% of children with congenital nephrotic syndrome. A total of 68 different mutations were detected in 20 of 33 steroid-resistant nephrotic syndrome genes. Fifteen of these mutations were novel. NPHS1, PLCE1, NPHS2, and SMARCAL1 were the most common genes in which we detected a mutation. In another 28% of families, we detected mutations in one or more candidate genes for steroid-resistant nephrotic syndrome. CONCLUSIONS: Whole exome sequencing is a sensitive approach toward diagnosis of monogenic causes of steroid-resistant nephrotic syndrome. A molecular genetic diagnosis of steroid-resistant nephrotic syndrome may have important consequences for the management of treatment and kidney transplantation in steroid-resistant nephrotic syndrome

    Effectiveness of some crown compounds on inhibition of polyphenoloxidase in model systems and in apple

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    Enzymatic browning is (in most cases) an undesirable reaction which usually impairs the sensory properties and chemical changes in raw fruits and vegetables after mechanical operations (such as peeling, coring or slicing). A great emphasis is put on research to develop new methods to prevent enzymatic browning especially in fresh-cut (minimally processed) fruits and vegetables. The inhibition effect of crown compounds, macrocyclic ethers, benzo-18-crown-6 with sorbic acid and benzo-18-crown-6 with potassium sorbate, on polyphenoloxidase (PPO) activity was studied. The effectiveness of these compounds was evaluated by using 3,4-dihydroxy phenylalanine (L-DOPA), and chlorogenic acid (3-o-caffeoyl-D-quinic acid), the most widespread natural PPO substrates in fruits and vegetables, as well as browning inhibition substances on the cut surface of apples. Results showed that crown compounds used in this study were effective, both as inhibitors of the oxidation of phenolic compounds (PPO substrates) in model solutions and as inhibitors of enzyme discolorations of real systems (fresh-cut apples). In the earlier published papers (V UKOVI C 'et al., 1999) the synthesis of crown compound used in this study was presented

    Influence of socioeconomic factors on pregnancy outcome in women with structural heart disease

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    OBJECTIVE: Cardiac disease is the leading cause of indirect maternal mortality. The aim of this study was to analyse to what extent socioeconomic factors influence the outcome of pregnancy in women with heart disease.  METHODS: The Registry of Pregnancy and Cardiac disease is a global prospective registry. For this analysis, countries that enrolled ≥10 patients were included. A combined cardiac endpoint included maternal cardiac death, arrhythmia requiring treatment, heart failure, thromboembolic event, aortic dissection, endocarditis, acute coronary syndrome, hospitalisation for cardiac reason or intervention. Associations between patient characteristics, country characteristics (income inequality expressed as Gini coefficient, health expenditure, schooling, gross domestic product, birth rate and hospital beds) and cardiac endpoints were checked in a three-level model (patient-centre-country).  RESULTS: A total of 30 countries enrolled 2924 patients from 89 centres. At least one endpoint occurred in 645 women (22.1%). Maternal age, New York Heart Association classification and modified WHO risk classification were associated with the combined endpoint and explained 37% of variance in outcome. Gini coefficient and country-specific birth rate explained an additional 4%. There were large differences between the individual countries, but the need for multilevel modelling to account for these differences disappeared after adjustment for patient characteristics, Gini and country-specific birth rate.  CONCLUSION: While there are definite interregional differences in pregnancy outcome in women with cardiac disease, these differences seem to be mainly driven by individual patient characteristics. Adjustment for country characteristics refined the results to a limited extent, but maternal condition seems to be the main determinant of outcome

    In vitro sensitivity testing of minimally passaged and uncultured gliomas with TRAIL and/or chemotherapy drugs

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    Background: Depression is common in individuals with diabetes. The present study is the first randomized controlled trial to test the efficacy of ω-3 ethyl-eicosapentaenoic acid (E-EPA) as adjuvant to antidepressant medication in the treatment of depression in adults with diabetes mellitus. Methods: In the VU University Medical Center, we conducted a 12-week, placebo-controlled, double-blind, parallel-group intervention study of E-EPA (1 g/day) versus placebo in 25 diabetes patients meeting DSM-IV criteria for major depressive disorder, who were already using antidepressant medication. The primary outcome was severity of depressive symptoms, assessed by the Montgomery Åsberg Depression Rating Scale (MADRS) at baseline and 12-week follow-up at two-weekly intervals. Blood samples were collected at baseline and at 12-week follow-up to determine EPA levels in erythrocyte membranes. Data were analyzed with ANOVA for repeated measures. Results: Thirteen participants were randomly assigned to E-EPA; 12 participants were given placebo. At 12-week follow-up, erythrocyte membranes from patients receiving E-EPA contained tripled levels of EPA, while no changes were noted in participants receiving placebo. In both groups, depressive symptoms significantly decreased over time (F = 21.14, p < 0.001), yet no significant differences were found between those treated with E-EPA versus placebo (F = 1.63, p = 0.17). Limitations: Although having sufficient study power, this study had a relatively small sample size. Small effects could not be detected, and dose-dependent effects could not be studied. Conclusions: No evidence was found for the efficacy of adding E-EPA to antidepressants in reducing depressive symptoms in diabetic patients with co-morbid depression. © 2009 Elsevier B.V. All rights reserved
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