177 research outputs found

    Energy efficient UV/H2O2 processes for conversion of pharmaceuticals in drinking water: effect of water quality

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    Previous research showed that surface water in the Netherlands may contain significant concentrations of organic micropollutants like pharmaceuticals. A model has been developed which can predict the conversion of a broad range of organic micropollutants in a UV/H2O2 process with low pressure UV lamps. This model also was applied to optimize UV reactors, which were tested at three Dutch locations, including two drinking water companies. It was observed that the model predictions were very accurate, that very high conversion could be obtained, and that the optimized UV reactors resulted in a 30-40% reduced energy demand of the process. Furthermore it was shown that the effect of pretreatment of the water, reducing the DOC content and increasing UV-T values, can improve reactor performance by 30-70%

    What's the effect of the implementation of general practitioner cooperatives on caseload? Prospective intervention study on primary and secondary care

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    <p>Abstract</p> <p>Background</p> <p>Out-of-hours care in the primary care setting is rapidly changing and evolving towards general practitioner 'cooperatives' (GPC). GPCs already exist in the Netherlands, the United Kingdom and Scandinavia, all countries with strong general practice, including gatekeepers' role. This intervention study reports the use and caseload of out-of-hours care before and after implementation of a GPC in a well subscribed region in a country with an open access health care system and no gatekeepers' role for general practice.</p> <p>Methods</p> <p>We used a prospective before/after interventional study design. The intervention was the implementation of a GPC.</p> <p>Results</p> <p>One year after the implementation of a GPC, the number of patient contacts in the intervention region significantly increased at the GPC (OR: 1.645; 95% CI: 1.439-1.880), while there were no significant changes in patient contacts at the Emergency Department (ED) or in other regions where a simultaneous registration was performed. Although home visits decreased in all general practitioner registrations, the difference was more pronounced in the intervention region (intervention region: OR: 0.515; 95% CI: 0.411-0.646, other regions: OR: 0.743; 95% CI: 0.608-0.908). At the ED we observed a decrease in the number of trauma cases (OR: 0.789; 95% CI: 0.648-0.960) and of patients who came to hospital by ambulance (OR: 0.687; 95% CI: 0.565-0.836).</p> <p>Conclusions</p> <p>One year after its implementation more people seek help at the GPC, while the number of contacts at the ED remains the same. The most prominent changes in caseload are found in the trauma cases. Establishing a GPC in an open health care system, might redirect some patients with particular medical problems to primary care. This could lead to a lowering of costs or a more cost-effective out of hours care, but further research should focus on effective usage to divert patient flows and on quality and outcome of care.</p

    Genetic disruption of sod1 gene causes glucose intolerance and impairs b-cell function

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    Oxidative stress has been associated with insulin resistance and type 2 diabetes. However, it is not clear whether oxidative damage is a cause or a consequence of the metabolic abnormalities present in diabetic subjects. The goal of this study was to determine whether inducing oxidative damage through genetic ablation of superoxide dismutase 1 (SOD1) leads to abnormalities in glucose homeostasis. We studied SOD1-null mice and wild-type (WT) littermates. Glucose tolerance was evaluated with intraperitoneal glucose tolerance tests. Peripheral and hepatic insulin sensitivity was quantitated with the euglycemic-hyperinsulinemic clamp. b-Cell function was determined with the hyperglycemic clamp and morphometric analysis of pancreatic islets. Genetic ablation of SOD1 caused glucose intolerance, which was associated with reduced in vivo b-cell insulin secretion and decreased b-cell volume. Peripheral and hepatic insulin sensitivity were not significantly altered in SOD1-null mice. High-fat diet caused glucose intolerance in WT mice but did not further worsen the glucose intolerance observed in standard chow-fed SOD1-null mice. Our findings suggest that oxidative stress per se does not play a major role in the pathogenesis of insulin resistance and demonstrate that oxidative stress caused by SOD1 ablation leads to glucose intolerance secondary to b-cell dysfunction. © 2013 by the American Diabetes Association

    Deletion of the Mitochondrial Superoxide Dismutase sod-2 Extends Lifespan in Caenorhabditis elegans

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    The oxidative stress theory of aging postulates that aging results from the accumulation of molecular damage caused by reactive oxygen species (ROS) generated during normal metabolism. Superoxide dismutases (SODs) counteract this process by detoxifying superoxide. It has previously been shown that elimination of either cytoplasmic or mitochondrial SOD in yeast, flies, and mice results in decreased lifespan. In this experiment, we examine the effect of eliminating each of the five individual sod genes present in Caenorhabditis elegans. In contrast to what is observed in other model organisms, none of the sod deletion mutants shows decreased lifespan compared to wild-type worms, despite a clear increase in sensitivity to paraquat- and juglone-induced oxidative stress. In fact, even mutants lacking combinations of two or three sod genes survive at least as long as wild-type worms. Examination of gene expression in these mutants reveals mild compensatory up-regulation of other sod genes. Interestingly, we find that sod-2 mutants are long-lived despite a significant increase in oxidatively damaged proteins. Testing the effect of sod-2 deletion on known pathways of lifespan extension reveals a clear interaction with genes that affect mitochondrial function: sod-2 deletion markedly increases lifespan in clk-1 worms while clearly decreasing the lifespan of isp-1 worms. Combined with the mitochondrial localization of SOD-2 and the fact that sod-2 mutant worms exhibit phenotypes that are characteristic of long-lived mitochondrial mutants—including slow development, low brood size, and slow defecation—this suggests that deletion of sod-2 extends lifespan through a similar mechanism. This conclusion is supported by our demonstration of decreased oxygen consumption in sod-2 mutant worms. Overall, we show that increased oxidative stress caused by deletion of sod genes does not result in decreased lifespan in C. elegans and that deletion of sod-2 extends worm lifespan by altering mitochondrial function

    Out of hours care: a profile analysis of patients attending the emergency department and the general practitioner on call

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    <p>Abstract</p> <p>Background</p> <p>Overuse of emergency departments (ED) is of concern in Western society and it is often referred to as 'inappropriate' use. This phenomenon may compromise efficient use of health care personnel, infrastructure and financial resources of the ED. To redirect patients, an extensive knowledge of the experiences and attitudes of patients and their choice behaviour is necessary. The aim of this study is to quantify the patients and socio-economical determinants for choosing the general practitioner (GP) on call or the ED.</p> <p>Methods</p> <p>Data collection was conducted simultaneously in 4 large cities in Belgium. All patients who visited EDs or used the services of the GP on call during two weekends in January 2005 were enrolled in the study in a prospective manner. We used semi-structured questionnaires to interview patients from both services.</p> <p>Results</p> <p>1611 patient contacts were suitable for further analysis. 640 patients visited the GP and 971 went to the ED. Determinants that associated with the choice of the ED are: being male, having visited the ED during the past 12 months at least once, speaking another language than Dutch or French, being of African (sub-Saharan as well as North African) nationality and no medical insurance. We also found that young men are more likely to seek help at the ED for minor trauma, compared to women.</p> <p>Conclusions</p> <p>Patients tend to seek help at the service they are acquainted with. Two populations that distinctively seek help at the ED for minor medical problems are people of foreign origin and men suffering minor trauma. Aiming at a redirection of patients, special attention should go to these patients. Informing them about the health services' specific tasks and the needlessness of technical examinations for minor trauma, might be a useful intervention.</p

    Mitochondrial Oxidative Stress Causes Hyperphosphorylation of Tau

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    Age-related neurodegenerative disease has been mechanistically linked with mitochondrial dysfunction via damage from reactive oxygen species produced within the cell. We determined whether increased mitochondrial oxidative stress could modulate or regulate two of the key neurochemical hallmarks of Alzheimer's disease (AD): tau phosphorylation, and ß-amyloid deposition. Mice lacking superoxide dismutase 2 (SOD2) die within the first week of life, and develop a complex heterogeneous phenotype arising from mitochondrial dysfunction and oxidative stress. Treatment of these mice with catalytic antioxidants increases their lifespan and rescues the peripheral phenotypes, while uncovering central nervous system pathology. We examined sod2 null mice differentially treated with high and low doses of a catalytic antioxidant and observed striking elevations in the levels of tau phosphorylation (at Ser-396 and other phospho-epitopes of tau) in the low-dose antioxidant treated mice at AD-associated residues. This hyperphosphorylation of tau was prevented with an increased dose of the antioxidant, previously reported to be sufficient to prevent neuropathology. We then genetically combined a well-characterized mouse model of AD (Tg2576) with heterozygous sod2 knockout mice to study the interactions between mitochondrial oxidative stress and cerebral Aß load. We found that mitochondrial SOD2 deficiency exacerbates amyloid burden and significantly reduces metal levels in the brain, while increasing levels of Ser-396 phosphorylated tau. These findings mechanistically link mitochondrial oxidative stress with the pathological features of AD

    Generation and characterisation of Friedreich ataxia YG8R mouse fibroblast and neural stem cell models

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    This article has been made available through the Brunel Open Access Publishing Fund.Background: Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disease caused by GAA repeat expansion in the first intron of the FXN gene, which encodes frataxin, an essential mitochondrial protein. To further characterise the molecular abnormalities associated with FRDA pathogenesis and to hasten drug screening, the development and use of animal and cellular models is considered essential. Studies of lower organisms have already contributed to understanding FRDA disease pathology, but mammalian cells are more related to FRDA patient cells in physiological terms. Methodology/Principal Findings: We have generated fibroblast cells and neural stem cells (NSCs) from control Y47R mice (9 GAA repeats) and GAA repeat expansion YG8R mice (190+120 GAA repeats). We then differentiated the NSCs in to neurons, oligodendrocytes and astrocytes as confirmed by immunocytochemical analysis of cell specific markers. The three YG8R mouse cell types (fibroblasts, NSCs and differentiated NSCs) exhibit GAA repeat stability, together with reduced expression of frataxin and reduced aconitase activity compared to control Y47R cells. Furthermore, YG8R cells also show increased sensitivity to oxidative stress and downregulation of Pgc-1α and antioxidant gene expression levels, especially Sod2. We also analysed various DNA mismatch repair (MMR) gene expression levels and found that YG8R cells displayed significant reduction in expression of several MMR genes, which may contribute to the GAA repeat stability. Conclusions/Significance: We describe the first fibroblast and NSC models from YG8R FRDA mice and we confirm that the NSCs can be differentiated into neurons and glia. These novel FRDA mouse cell models, which exhibit a FRDA-like cellular and molecular phenotype, will be valuable resources to further study FRDA molecular pathogenesis. They will also provide very useful tools for preclinical testing of frataxin-increasing compounds for FRDA drug therapy, for gene therapy, and as a source of cells for cell therapy testing in FRDA mice. © 2014 Sandi et al

    Diagnostic scope in out-of-hours primary care services in eight European countries: an observational study

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    Background: In previous years, out- of-hours primary care has been organised in large-scale organisations in many countries. This may have lowered the threshold for many patients to present health problems at nights and during the weekend. Comparisons of out-of-hours care between countries require internationally comparable figures on symptoms and diagnoses, which were not available. This study aimed to describe the symptoms and diagnoses in out-of-hours primary care services in regions in eight European countries. Methods: We conducted a retrospective observational study based on medical records from out-of-hours primary care services in Belgium, Denmark, Germany, the Netherlands, Norway, Slovenia, Spain, and Switzerland. We aimed to include data on 1000 initial contacts from up to three organisations per country. Excluded were contacts with an administrative reason. The International Classification for Primary Care (ICPC) was used to categorise symptoms and diagnoses. In two countries (Slovenia and Spain) ICD10 codes were translated into ICPC codes. Results: The age distribution of patients showed a high consistency across countries, while the percentage of males varied from 33.7% to 48.3%. The ICPC categories that were used most frequently concerned: chapter A 'general and unspecified symptoms' (mean 13.2%), chapter R 'respiratory' (mean 20.4%), chapter L 'musculoskeletal' (mean 15.0%), chapter S 'skin' (mean 12.5%), and chapter D 'digestive' (mean 11.6%). So, relatively high numbers of patients presenting with infectious diseases or acute pain related syndromes. This was largely consistent across age groups, but in some age groups chapter H ('ear problems'), chapter L ('musculoskeletal') and chapter K ('cardiovascular') were frequently used. Acute life-threatening problems had a low incidence. Conclusions: This international study suggested a highly similar diagnostic scope in out-of-hours primary care services. The incidence rates of acute life-threatening health problems were low in all countries

    Learning physical examination skills outside timetabled training sessions: what happens and why?

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    Lack of published studies on students’ practice behaviour of physical examination skills outside timetabled training sessions inspired this study into what activities medical students undertake to improve their skills and factors influencing this. Six focus groups of a total of 52 students from Years 1–3 using a pre-established interview guide. Interviews were recorded, transcribed and analyzed using qualitative methods. The interview guide was based on questionnaire results; overall response rate for Years 1–3 was 90% (n = 875). Students report a variety of activities to improve their physical examination skills. On average, students devote 20% of self-study time to skill training with Year 1 students practising significantly more than Year 3 students. Practice patterns shift from just-in-time learning to a longitudinal selfdirected approach. Factors influencing this change are assessment methods and simulated/real patients. Learning resources used include textbooks, examination guidelines, scientific articles, the Internet, videos/DVDs and scoring forms from previous OSCEs. Practising skills on fellow students happens at university rooms or at home. Also family and friends were mentioned to help. Simulated/real patients stimulated students to practise of physical examination skills, initially causing confusion and anxiety about skill performance but leading to increased feelings of competence. Difficult or enjoyable skills stimulate students to practise. The strategies students adopt to master physical examination skills outside timetabled training sessions are self-directed. OSCE assessment does have influence, but learning takes place also when there is no upcoming assessment. Simulated and real patients provide strong incentives to work on skills. Early patient contacts make students feel more prepared for clinical practice

    A CRISPR screen identifies a pathway required for paraquat-induced cell death

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    Paraquat, a herbicide linked to Parkinson's disease, generates reactive oxygen species (ROS), which causes cell death. Because the source of paraquat-induced ROS production remains unknown, we conducted a CRISPR-based positive-selection screen to identify metabolic genes essential for paraquat-induced cell death. Our screen uncovered three genes, POR (cytochrome P450 oxidoreductase), ATP7A (copper transporter), and SLC45A4 (sucrose transporter), required for paraquat-induced cell death. Furthermore, our results revealed POR as the source of paraquat-induced ROS production. Thus, our study highlights the use of functional genomic screens for uncovering redox biology
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