980 resultados para selective catalytic reduction


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Interferon alfa therapy for chronic hepatitis C infection is commonly associated with neuropsychiatric symptoms, including depression. These side effects may necessitate reduction or even cessation of interferon alfa, hut there is little information regarding the management of this important problem. We report 10 cases of interferon-alfa-induced depressive disorder treated with the selective serotonin reuptake inhibitor sertraline. All patients obtained rapid symptom relief without the need for reduction or cessation of interferon alfa.

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Objectives-To investigate the feasibility of selective screening for abdominal aortic aneurysm (AAA) based on identification of a target group of manageable size defined by risk factors for AAA. Setting-Male residents of Perth, Western Australia, aged 65-83 years, who participated in a randomised controlled trial of ultrasound screening for AAA. Methods-Eligible men were identified from the electoral roll and invited to attend a screening clinic. Those who attended completed a questionnaire, had a limited physical examination, and underwent an ultrasound examination to identify the maximum diameter of the infrarenal aorta. Data on risk factors collected from the first 8995 men seen were used to calculate a multivariate risk score for the remaining 2755 men who were screened. Gentiles of the risk score were used to define potential target groups for screening and the sensitivity and specificity of each of these selective screening strategies were calculated. We repeated the calculation separately for AAAs of at least 30 mm, 40 mm, and 50 mm in diameter. Results-We found that screening half of the male population aged 65-83 years would find approximately 75% of AAAs, regardless of their size, whereas screening only current smokers in this population would find approximately 20% of AAAs. Conclusions-Selective screening for AAA using easily recognisable risk factors is feasible but is not worthwhile as approximately 25% of clinically significant cases would be missed.

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Naltrexone has been demonstrated in western studies to be a useful pharmacological adjunct within treatment programmes for alcoholic patients. We report the first study of its efficacy and usefulness in an Asian region. This project was designed to allow naltrexone's performance to be assessed under routine clinical conditions but with patients selected on the basis of their being likely to comply. Following in-patient detoxification, 53 male alcohol-dependent patients admitted to the Alcohol Treatment Centre at Woodbridge Hospital, Singapore, were enrolled in a 12-week, placebo-controlled trial of naltrexone hydrochloride (50 mg/day). Subjects were randomized on a 2:1 basis, with 35 receiving naltrexone and 18 receiving placebo. Analyses identified that a higher percentage of naltrexone patients completed the study (40% vs. 22%). In the study non-completers, the dropout rate due to drinking relapse was also lower in the naltrexone group (9% vs. 43%). Of the 39 patients for whom drinking status over the trial could be ascertained, fewer naltrexone-treated patients drank (33% vs. 53%). Alcohol craving scores also showed a selective and distinct reduction in the naltrexone-treated group. Results suggest that naltrexone may be an effective and safe aid to treatment of alcohol dependent patients in Asian patients, for whom the aims are to reduce alcohol craving and drinking reinstatement, but where compliance is likely to be low.

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In previous studies we have shown that the sensitivity of melanoma cell lines to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)induced apoptosis was determined largely by the level of expression of death receptor TRAIL receptor 2 on the cells. However, approximately one-third of melanoma cell lines were resistant to TRAIL, despite expression of high levels of TRAIL receptor 2. The present studies show that these cell lines had similar levels of TRAIL-induced activated caspase-3 as the TRAIL-sensitive lines, but the activated caspase-3 did not degrade substrates downstream of caspase-3 [inhibitor of caspase-activated DNase and poly(ADP-ribose) polymerase]. This appeared to be due to inhibition of caspase-3 by X-linked inhibitor of apoptosis (XIAP) because XIAP was bound to activated caspase-3, and transfection of XIAP into TRAIL-sensitive cell lines resulted in similar inhibition of TRAIL-induced apoptosis. Conversely, reduction of XIAP levels by overexpression of Smac/ DIABLO in the TRAIL-resistant melanoma cells was associated with the appearance of catalytic activity by caspase-3 and increased TRAIL-induced apoptosis. TRAIL was shown to cause release of Smac/DIABLO from mitochondria, but this release was greater in TRAIL-sensitive cell lines than in TRAIL-resistant cell lines and was associated with downregulation of XIAP levels. Furthermore, inhibition of Smac/DIABLO release by overexpression of Bcl-2 inhibited down-regulation of XIAP levels. These results suggest that Smac/DIABLO release from mitochondria and its binding to XIAP are an alternative pathway by which TRAIL induces apoptosis of melanoma, and this pathway is dependent on the release of activated caspase-3 from inhibition by XIAP and possibly other inhibitor of apoptosis family members.

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Metal oxide pillared clay (PILC) possesses several interesting properties, such as large surface area, high pore volume and tunable pore size (from micropore to mesopore), high thermal stability, strong surface acidity and catalytic active substrates/metal oxide pillars. These unique characteristics make PILC an attractive material in catalytic reactions. It can be made either as catalyst support or directly used as catalyst. This paper is a continuous work from Kloprogge's review (J.T. Kloprogge, J. Porous Mater. 5, 5 1998) on the synthesis and properties of smectites and related PILCs and will focus on the diverse applications of clay pillared with different types of metal oxides in the heterogeneous catalysis area and adsorption area. The relation between the performance of the PILC and its physico-chemical features will be addressed.

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Hepatitis C virus (HCV) is a major cause of chronic liver disease that may progress to cirrhosis. Antiviral treatment is successful in less than 50% of patients, is costly and causes debilitating side effects. For these reasons, additional therapies to limit the progression of liver disease are urgently required. Steatosis is found in 60% of patients with HCV and is strongly associated with more severe fibrosis. Improvements in biochemical parameters may be seen with weight reduction, however the effects on liver histology have not been investigated. We propose that in patients with chronic HCV and steatosis, obesity contributes to fat in the liver, which results in increased fibrosis and progression to cirrhosis. This study investigated the effect of weight reduction on liver biochemistry and histology in patients with HCV and the success of weight maintenance after an intensive intervention. We examined the effect of a 12 week diet and exercise program where all subjects were seen weekly by the Dietician, with the goal of achieving a 0.5 kg weight loss per week. Biochemistry was monitored monthly and a liver biopsy was performed prior to and 3-6 months after the intervention period. Patients then entered a 12 month weight maintenance program with monthly dietetic review. After 12 weeks there was a mean weight loss of 5.9 ± 3.2 kg and a mean reduction in waist circumference of 9.0 ± 5.0 cm. In 16 of the 19 patients, serum ALT levels fell progressively with weight loss. Mean fasting insulin fell from 16 to 11 mmol/L (p

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Steatosis occurs in >50% of patients with chronic HCV. In patients with viral genotype 3, steatosis may be a cytopathic effect of the virus. However in many patients with HCV, the pathogenesis of steatosis appears to be the same as for patients with non-alcoholic fatty liver disease (NAFLD) ie related to increased body mass index (BMI). We studied the effect of a 12 week weight reduction program on metabolic parameters in subjects with chronic HCV genotype 1 (Group 1, n = 16), genotype 3 (Group 2, n = 13) and patients with NAFLD (Group 3, n = 13). A liver biopsy was performed prior to and 3-6 months after the intervention period in 15 patients. The mean (SD) BMI of subjects in groups 1, 2 and 3 was 30.7 (4.0), 29.0 (5.2) and 33.3 (7.7), respectively. There was no significant difference in the amount of weight loss, change in waist circumference, change in ALT or reduction in steatosis between the 3 groups. Mean (SD) weight loss was 5.1 (3.7) kg. In those patients who lost weight, serum insulin (mean (SD) mU/L) changed from 17.8 (7.8) to 11.5 (4.8) (p = 0.003), 12.4 (5.0) to 8.4 (4.3) (p = 0.02), and 16.9 (7.3) to 17.8 (8.1) (p = 0.76) in Groups 1, 2 and 3, respectively. A small amount of weight loss is associated with a reduction in circulating insulin levels in patients with chronic HCV, particularly in genotype 1. In patients with NAFLD, the lack of a significant decrease in circulating insulin with weight reduction may reflect the higher initial BMI or may be due to the pathogenesis of this disorder.

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Objective: To assess from a health sector perspective the incremental cost-effectiveness of interventions for generalized anxiety disorder (cognitive behavioural therapy [CBT] and serotonin and noradrenaline reuptake inhibitors [SNRIs]) and panic disorder (CBT, selective serotonin reuptake inhibitors [SSRIs] and tricyclic antidepressants [TCAs]). Method: The health benefit is measured as a reduction in disability-adjusted life years (DALYs), based on effect size calculations from meta-analyses of randomised controlled trials. An assessment on second stage filters ('equity', 'strength of evidence', 'feasibility' and 'acceptability to stakeholders') is also undertaken to incorporate additional factors that impact on resource allocation decisions. Costs and benefits are calculated for a period of one year for the eligible population (prevalent cases of generalized anxiety disorder/panic disorder identified in the National Survey of Mental Health and Wellbeing, extrapolated to the Australian population in the year 2000 for those aged 18 years and older). Simulation modelling techniques are used to present 95% uncertainty intervals (UI) around the incremental cost-effectiveness ratios (ICERs). Results: Compared to current practice, CBT by a psychologist on a public salary is the most cost-effective intervention for both generalized anxiety disorder (A$6900/DALY saved; 95% UI A$4000 to A$12 000) and panic disorder (A$6800/DALY saved; 95% UI A$2900 to A$15 000). Cognitive behavioural therapy results in a greater total health benefit than the drug interventions for both anxiety disorders, although equity and feasibility concerns for CBT interventions are also greater. Conclusions: Cognitive behavioural therapy is the most effective and cost-effective intervention for generalized anxiety disorder and panic disorder. However, its implementation would require policy change to enable more widespread access to a sufficient number of trained therapists for the treatment of anxiety disorders.

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The 19-amino acid conopeptide (rho-TIA) was shown previously to antagonize noncompetitively alpha(1B)-adrenergic receptors (ARs). Because this is the first peptide ligand for these receptors, we compared its interactions with the three recombinant human alpha(1)-AR subtypes (alpha(1A), alpha(1B), and alpha(1D)). Radioligand binding assays showed that rho-TIA was 10-fold selective for human alpha(1B)- over alpha(1A)- and alpha(1D)-ARs. As observed with hamster alpha(1B)-ARs, rho-TIA decreased the number of binding sites (B-max) for human alpha(1B)-ARs without changing affinity (K-D), and this inhibition was unaffected by the length of incubation but was reversed by washing. However, rho-TIA had opposite effects at human alpha(1A)-ARs and alpha(1D)-ARs, decreasing KD without changing Bmax, suggesting it acts competitively at these subtypes. rho-TIA reduced maximal NE-stimulated [H-3] inositol phosphate formation in HEK293 cells expressing human alpha(1B)-ARs but competitively inhibited responses in cells expressing alpha(1A)- or alpha(1D)-ARs. Truncation mutants showed that the amino-terminal domains of alpha(1B)- or alpha(1D)-ARs are not involved in interaction with rho-TIA. Alanine-scanning mutagenesis of rho-TIA showed F18A had an increased selectivity for alpha(1B)-ARs, and F18N also increased subtype selectivity. I8A had a slightly reduced potency at alpha(1B)-ARs and was found to be a competitive, rather than noncompetitive, inhibitor in both radioligand and functional assays. Thus rho-TIA noncompetitively inhibits alpha(1B)-ARs but competitively inhibits the other two subtypes, and this selectivity can be increased by mutation. These differential interactions do not involve the receptor amino termini and are not because of the charged nature of the peptide, and isoleucine 8 is critical for its noncompetitive inhibition at alpha(1B)-ARs.

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This work describes the catalytic activity of manganese and iron porphyrins, Mn and Fe(TFPP)Cl, covalently immobilized on the aminofunctionalized supports montmorillonite K-10 (MontX) and silica (SilX), where X= 1 or 2 represents the length of the organic chain (""arms"") binding the metalloporphyrin to the support. These systems were characterized by UV-vis and Electronic Paramagnetic Resonance (EPR), and they were used as catalysts in the oxidation of carbamazepine (CBZ) by the oxidants iodosylbenzene (PhIO) and hydrogen peroxide. The manganese porphyrin (MnP) catalysts proved to be efficient and selective for the epoxide, the main CBZ metabolite in natural systems. MnMont1 was an excellent catalyst when PhIO was used as oxidant, even better than the same MnP in homogeneous system. Supports bearing short ""arms"" led to the best yields. Although H2O2 is an environmentally friendly oxidant, low product yields were obtained when it was employed in CBZ oxidation. Fe(TFPP)CI immobilized on aminofunctionalized supports was not an efficient catalyst, probably due to the presence of Fe(H) species in the matrix, which led to the less reactive intermediate PFe(IV)(O). (c) 2007 Elsevier B.V. All rights reserved.

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In this work, we report the synthesis, characterization and catalytic properties of a vanadium oxide-silicon oxide composite xerogel prepared by a soft chemistry approach. In order to obtain such material, we submitted a vanadium pentoxide gel previously synthesized via protonation of metavanadate species to an ""in situ"" progressive polycondensation into silica gel. The material has been characterized by X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. Further, the catalytic activity of this material was evaluated for the epoxidation of styrene and cyclooctene using iodosylbenzene, hydrogen peroxide and m-chloroperbenzoic acid as the oxidizing agent.

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Although lacking catalytic activity, the Lys49-PLA(2)s damage artificial membranes by a Ca2+-independent mechanism, and demonstrate a potent bactericidal effect. The relationship between the membrane-damaging activity and bactericidal effect of bothropstoxin-I (BthTx-1), a Lys49-PLA(2) from the venom of Bothrops jararacussu, was evaluated for the wildtype protein and a series of site-directed mutants in the active site and C-terminal regions of the protein. The membrane permeabilization effect against the inner and outer membranes of Escherichia coli K12 was evaluated by fluorescence changes of Sytox Green and N-phenyl-N-naphthylamine, respectively. With the exception of H48Q, all mutants reduced the bactericidal activity, which correlated with a reduction of the permeabilization effect both against the inner bacterial membrane. No significant differences in the permeabilization of the bacterial outer membrane were observed between the native, wild-type recombinant and mutant proteins. These results suggest different permeabilization mechanisms against the inner and outer bacterial membranes. Furthermore, the structural determinants of bacterial inner membrane damage identified in this study correlate with those previously observed for artificial membrane permeabilization, suggesting that a common mechanism of membrane damage underlies the two effects. (C) 2007 Elsevier Ltd. All rights reserved.

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Different compositions of Pt, PtNi, PtSn, and PtSnNi electrocatalysts supported on carbon Vulcan XC-72 were prepared through thermal decomposition of polymeric precursors. The nanoparticles were characterized by morphological and structural analyses (XRD, TEM, and EDX). XRD results revealed a face-centered cubic structure for platinum, and there was evidence that Ni and Sn atoms are incorporated into the Pt structure. The electrochemical investigation was carried out in slightly acidic medium (H(2)SO(4) 0.05 mol L(-1)), in the absence and in the presence of ethanol. Addition of Ni to Pt/C and PtSn/C catalysts significantly shifted the onset of ethanol and CO oxidations toward lower potentials, thus enhancing the catalytic activity, especially in the case of the ternary PtSnNi/C composition. Electrolysis of ethanol solutions at 0.4 V us. RHE allowed for determination of acetaldehyde and acetic acid as the reaction products, as detected by HPLC analysis. Due to the high concentration of ethanol employed in the electrolysis experiments (1.0 mol L(-1)), no formation of CO(2) was observed. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

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This naphthalene diimide derivative, DC18, forms highly conjugated semiconducting stacked assemblies over electrodes after electrochemical conditioning. These molecular materials are very efficient towards electrochemical photoreduction of oxygen under visible light.

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The commercially available Jacobsen catalyst, Mn(salen), was occluded in hybrid polymeric membranes based on poly(dimethylsiloxane) (PDMS) and poly(vinyl alcohol) (PVA). The obtained systems were characterized by UV-vis spectroscopy and SEM techniques. The membranes were used as a catalytic barrier between two different phases: an organic substrate phase (cyclooctene or styrene) in the absence of solvent, and an aqueous solution of either t-BuOOH or H(2)O(2). Membranes containing different percentages of PVA were prepared, in order to modulate their hydrophilic/hydrophobic swelling properties. The occluded complex proved to be an efficient catalyst for the oxidation of alkenes. The new triphasic system containing a cheap and easily available catalyst allowed substrate oxidation and easy product separation using ""green"" oxidants. (C) 2010 Elsevier B.V. All rights reserved.