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Search Results: 1 - 10 of 18527 matches for " U. Drost "
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Provenance and early diagenetic processes of the Ordovician árka Formation at Praha - erveny vrch Hill (Barrandian, Czech Republic)
Drost K,Linnemann U,Wemmer K,Budil P
Bulletin of Geosciences , 2003, DOI: 10.3140/bull.geosci.2003.02.147
Abstract: Shales and siliceous nodules from Praha - erveny vrch Hill (Middle Ordovician, árka Formation, Barrandian area) were studied by chemical and X-ray phase analyses as well as by K-Ar age dating to specify their formation and provenance. White micas occurring as detrital components within the shales of the árka Formation reveal a Neoproterozoic (Cadomian) K-Ar age (599 ± 12 Ma) of the source rocks. The enrichment of heavy rare earth elements (HREE) over light rare earth elements (LREE), high Th/U ratios, and a distinct kaolinite content in the shales of the árka Formation point to strong chemical weathering of the source area in pre-Middle Ordovician times. Major element data indicate a passive margin setting for these shales, whereas trace element data and discriminant function analysis display the inherited island arc signature of the Neoproterozoic basement. Very low sulphide sulphur (Spyrite) and organic carbon (Corg) contents as well as the depletion in Fe and Mn are interpreted as a tracer for oxic bottom-water conditions during deposition and transport of these elements by bottom currents. The growth of the siliceous nodules is supposed to be connected with the replacement of former sediment by SiO2 and with leaching of most elements simultaneously with the enrichment in Mn, Ca, Co, Pb, Y and HREE.
Dietary and Intraperitoneal Administration of Selenium Provide Comparable Protection in the 6-Hydroxydopamine Lesion Rat Model of Parkinson's Disease
Sarah Mueller,Melissa Drost,Cecilia M. Fox
Impulse : an Undergraduate Journal for Neuroscience , 2007,
Abstract: Significant research implicates the involvement of free radicals in the manifestation of Parkinson's disease. The antioxidant, selenium is a vital dietary component for mammals. It is present in the active center of glutathione peroxidase, an antioxidant enzyme that scavenges peroxides and protects membrane lipids and macromolecules from oxidative insult. The purpose of this research was to determine an effective means of delivering selenium as well as an appropriate time frame for antioxidant administration that would elicit a protective response in rats challenged with an intranigral 6-hydroxydopamine (6-OHDA) lesion. In the first part of this study, Fischer 344 rats were placed into one of four groups: selenium enhanced diet, control diet, intraperitoneal injection of selenium as Na2SeO3 or intraperitoneal injection of distilled water. All treatments were delivered prior to an intranigral 6-OHDA lesion. Animals were euthanized two weeks post lesion and their brains processed for tyrosine hydroxylase (TH) immunocytochemistry. Average dopamine neuron survival in the substantia nigra of control animals was less than 22%; whereas nigral dopamine neuron survival in the selenium fed group was 49.7% and 56.0% in the selenium injected group. Based on these results, a subsequent study was designed utilizing the selenium enhanced diet method of antioxidant administration. To examine the neuroprotective effect of long-term selenium treatment, pregnant Fischer 344 rats were exposed to either selenium enhanced or control rat chow. Their pups were treated with the same diet as their mothers and lesioned with 6-OHDA at two months of age. Animals were euthanized and their brains were processed for TH immunocytochemistry. Nigral dopamine neuron survival for the selenium treated animals was significantly protective (59%) when compared to the control chow fed animals (29.6%). However, when compared to the short-term exposure of selenium rat chow in the previous study, there was no significant increase in neuroprotection.
The effect of lipocortin 1 on neutrophil deformability
E. M. Drost,W. MacNee,S. F. Smith
Mediators of Inflammation , 1996, DOI: 10.1155/s0962935196000257
Diminished peroxisome proliferator-activated receptor (PPAR) regulation as a potential mechanism for the persistent inflammation in chronic obstructive pulmonary disease
E. M. Drost,C. A. Poland,K. Donaldson,W. MacNee
European Respiratory Review , 2006,
Abstract: Persistent inflammation is the main pathological process that underlies COPD. Understanding this inflammatory response is a key focus of COPD research with the aim of discovering new therapeutic targets. The nuclear hormone receptor, PPAR is now a recognised modulator of inflammation in various chronic inflammatory conditions, but its role in the persistent airways inflammation in COPD has not been examined. Control of the inflammatory response by PPAR has been shown by antagonising inflammatory signalling pathways, such as NF-kappa B and AP-1. PPAR-alpha protein levels in lung tissue from patients with COPD were assessed by Western blot. In vitro assays using the human type II alveolar epithelial cell line were performed to assess the effect of PPAR-alpha agonist treatment on inflammatory cytokine generation. An increase in PPAR-alpha protein levels was seen for healthy smokers compared with non-smokers (Ratio to beta-actin loading control, non-smokers 0.61±0.1, n = 10; healthy smokers 0.97±0.3, n = 11, p>0.05). No increase was seen for current smoker or ex-smoker COPD patients (0.36±0.08, n = 12; 0.49±0.1, n = 8 respectively). In vitro experiments with a human type II alveolar epithelial cell line demonstrated a diminished inflammatory response to TNF-alpha, as measured by the generation of the pro-inflammatory cytokine IL-8, following pre-treatment with the PPAR-alpha agonist, WY-14643 (IL-8 generation, control 823±22 pg·ml–1, TNF-alpha 7491±530 pg·ml–1 p<0.001, WY-14643 2559±46 pg·ml–1 p<0.05, n = 3). We propose PPAR agonists as a potential therapy for reducing the NF-B-regulated inflammation in COPD airways.
Cytotoxicity and Induction of Inflammation by Pepsin in Acid in Bronchial Epithelial Cells
Erik Bathoorn,Paul Daly,Birgit Gaiser,Karl Sternad,Craig Poland,William MacNee,Ellen M. Drost
International Journal of Inflammation , 2011, DOI: 10.4061/2011/569416
Abstract: Introduction. Gastroesophageal reflux has been associated with chronic inflammatory diseases and may be a cause of airway remodelling. Aspiration of gastric fluids may cause damage to airway epithelial cells, not only because acidity is toxic to bronchial epithelial cells, but also since it contains digestive enzymes, such as pepsin. Aim. To study whether pepsin enhances cytotoxicity and inflammation in airway epithelial cells, and whether this is pH-dependent. Methods. Human bronchial epithelial cells were exposed to increasing pepsin concentrations in varying acidic milieus, and cell proliferation and cytokine release were assessed. Results. Cell survival was decreased by pepsin exposure depending on its concentration ( ) and pH level of the medium ( ) (both ). Pepsin-induced interleukin-8 release was greater at lower pH ( ; ). Interleukin-6 induction by pepsin was greater at pH 1.5 compared to pH 2.5 (mean difference 434%; ). Conclusion. Pepsin is cytotoxic to bronchial epithelial cells and induces inflammation in addition to acid alone, dependent on the level of acidity. Future studies should assess whether chronic aspiration causes airway remodelling in chronic inflammatory lung diseases. 1. Introduction Aspiration of gastric fluids damages airway epithelial cells [1] due to the toxicity of its low pH [2]. Several in vivo and in vitro models have assessed the effect of acid aspiration on lung injury and inflammation, using a hydrochloric acid solution with a pH ranging from 1 to 1.5 [2–5]. In addition, gastric particles have been found to contribute to lung injury [6]. Previous in vivo and in vitro studies have shown that acid aspiration causes an IL-6 and IL-8 mediated neutrophil influx into the lungs [2, 3, 7, 8]. A correlation between acid aspiration, increased IL-8 levels, and airway neutrophil counts has been found in asthma patients [9]. However, the acidity of gastric fluids might not be the only cause of damage and inflammatory response. Digestive enzymes such as pepsin might be an important factor as well. Pepsin is stored as inactive pepsinogen in the chief cells of the gastric mucosa. It is a protease involved in the digestion of food, and its activity is acid-dependent. The conversion of pepsinogen to pepsin in the stomach starts slowly at pH 6 and reaches optimal activity between pH 1.5 to 2.5. Above pH 6.8, pepsin becomes inactive and above pH 7.5 it is fully inactive and irreversibly denatured [10]. In human gastric fluid, the pH varies from 1.5 to 3, which agrees with pepsin’s activity optimum, and the concentration of pepsin varies
Abatacept with methotrexate versus other biologic agents in treatment of patients with active rheumatoid arthritis despite methotrexate: a network meta-analysis
Patricia Guyot, Peter Taylor, Robin Christensen, Louisa Pericleous, Coralie Poncet, Maximilian Lebmeier, Pieter Drost, Gert Bergman
Arthritis Research & Therapy , 2011, DOI: 10.1186/ar3537
Abstract: A systematic literature review identified controlled trials investigating the efficacy of abatacept (three studies), etanercept (two studies), infliximab (two), adalimumab (two), certolizumab pegol (two) ritixumab (three), and tocilizumab (two) in MTX-IR patients with RA. The clinical trials included in this analysis were similar with respect to trial design, baseline patient characteristics and background therapy (MTX). The key clinical endpoints of interest were HAQ CFB, ACR-50 and DAS28 < 2.6 measured at 24 and 52 weeks. The results were analysed using network meta-analysis methods that enabled calculation of an estimate for expected relative effect of comparative treatments. Analysis results were expressed as the difference in HAQ CFB score and odds ratio (OR) of achieving an ACR-50 and DAS28 response and associated 95% credible intervals (CrI).The analysis of HAQ CFB at 24 weeks and 52 weeks showed that abatacept in combination with MTX is expected to be more efficacious than MTX monotherapy and is expected to show a comparable efficacy relative to other biologic DMARDs in combination with MTX. Further, abatacept showed comparable ACR-50 and DAS28 < 2.6 response rates with other biologic DMARDs at 24 and 52 weeks, except for ACR-50 compared to certolizumab pegol at 52 weeks and for DAS28 < 2.6 compared to tocilizumab at 24 weeks. Sensitivity analyses confirmed the robustness of the findings.Abatacept in combination with MTX is expected to result in a comparable change from baseline in HAQ score and comparable ACR-50 and DAS28 < 2.6 response rates in MTX-IR patients compared to other approved biologic agents.Rheumatoid arthritis (RA) is a chronic, disabling systemic inflammatory disorder, with immune-mediated attacks of the synovial joints. Disease-modifying anti-rheumatic drugs (DMARDs) alleviate the symptoms of RA and have the potential to slow or stop disease progression [1-3]. DMARDs are classified into two types: conventional and biologic. European Guidelin
Perfluorooctanoic acid (PFOA) — main concerns and regulatory developments in Europe from an environmental point of view
Lena Vierke, Claudia Staude, Annegret Biegel-Engler, Wiebke Drost, Christoph Schulte
Environmental Sciences Europe , 2012, DOI: 10.1186/2190-4715-24-16
Abstract: PFOA is persistent in the environment, ubiquitous present in surface waters, and subject to long-range transport. It accumulates in biota, especially in top predators. PFOA is increasingly analyzed in food items, and in drinking water. PFOA’s intrinsic properties such as its persistency (P), its potential for bioaccumulation (B) and its toxicity (T) suggest that PFOA is a promising candidate for being identified as a Substance of Very High Concern (SVHC) under REACH. Because of the dispersive occurrence of PFOA in the environment, the presence in imported products, and the use of PFCs, which can degrade to PFOA in various consumer products, a restriction under REACH seems to be the most effective regulatory measure to minimize human and environmental exposure to PFOA in the European Union.Due to its intrinsic properties, PFOA fulfills the REACH PBT-criteria. The next regulatory step will be the identification of PFOA and its ammonium salt (APFO) as SVHC according to REACH and the addition to the REACH Candidate List. As a second step, a restriction proposal will be prepared to include both substances and precursors into REACH Annex XVII.Per- and polyfluorinated chemicals (PFCs) are emerging pollutants of the 21st century. These man-made chemicals have been produced since the 1950s. Due to their outstanding properties – they provide water, oil, and grease repellency and are very stable ? certain PFCs have been used in a variety of consumer products. A number of studies are available reporting the occurrence of these chemicals in all environmental media as well as in humans [1-4]. In total, according to an OECD survey, the group of produced and used PFCs consists of more than 600 compounds [5]. They are characterized by a fully (per-) or partly (poly-) fluorinated carbon chain in connection with different functional groups. Two compounds from the PFC family are well known: Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). PFOS has recently been i
Effects of shared medical appointments on quality of life and cost-effectiveness for patients with a chronic neuromuscular disease. Study protocol of a randomized controlled trial
Femke M Seesing, Gea Drost, Gert-Jan van der Wilt, Baziel GM van Engelen
BMC Neurology , 2011, DOI: 10.1186/1471-2377-11-106
Abstract: A randomized, prospective controlled study (RCT) with a follow up of 6 months will be conducted to evaluate the clinical and cost-effectiveness of shared medical appointments compared to usual care for 300 neuromuscular patients and their partners at the Radboud University Nijmegen Medical Center. Every included patient will be randomly allocated to one of the two study arms. This study has been reviewed and approved by the medical ethics committee of the region Arnhem-Nijmegen, the Netherlands. The primary outcome measure is quality of life as measured by the EQ-5D, SF-36 and the Individualized neuromuscular Quality of Life Questionnaire. The primary analysis will be an intention-to-treat analysis on the area under the curve of the quality of life scores. A linear mixed model will be used with random factor group and fixed factors treatment, baseline score and type of neuromuscular disease. For the economic evaluation an incremental cost-effectiveness analysis will be conducted from a societal perspective, relating differences in costs to difference in health outcome. Results are expected in 2012.This study will be the first randomized controlled trial which evaluates the effect of shared medical appointments versus usual care for neuromuscular patients. This will enable to determine if there is additional value of shared medical appointments to the current therapeutical spectrum. When this study shows that group visits produce the alleged benefits, this may help to increase the acceptance of this innovative and creative way of using one of the most precious resources in health care more efficiently: time.DutchTrial Register http://www.trialregister.nl webciteNTR1412As of January 2006, the department of neurology at the RUNMC has started offering shared medical appointments or group visits to patients with a neuromuscular disease. This novel approach of delivering outpatient care is now being compared with usual care during a randomized controlled trial with 300 pa
Phytochemical investigation of the tomatillo fruit (Physalis ixocarpa Brot., Solanaceae)
K. Drost-Karbowska,M. Ellnain-Wojtaszek,A. Gawron-Gzella,Z. Kowalewski
Acta Societatis Botanicorum Poloniae , 1993, DOI: 10.5586/asbp.1993.023
Abstract: The occurence of alkaloids, witanolides, saponosides and flavonoids was investigated in the fruits of tomatillo (Physalis ixocarpa Brot.) cv. Bujna and Rendidora. The tomatillo is commonly cultivated in Mexico and has been introduced on a small scale in Poland. The chromatographic analysis of alkaloids showed only trace amounts of compounds reacting with the Dragendorff reagent. In the fraction of quaternary alkaloids soluble in water, only choline was found. Witanolides were not detected in tomatillo fruits. The saponosides were found only in trace amounts and their hemolytic indexes as well as saponification numbers were very low. Flavonoids were represented by the derivatives of quercetine differring with their sugar moieties attached to the hydroxyl group at C-3. It is concluded that the toxic compounds which would be harmful to human health were not found in tomatillo fruits. The presence of choline in them, as well as of flavonoids belonging to the vitamin P group is advantageous for health.
Wall across the Atlantic Drift Bottles Released by Students Confirm that the Gulf Stream Prevents Subarctic Surface Drifters from Escaping South
Curtis C. Ebbesmeyer,Igor M. Belkin,Helen E. Drost,Sarah Zimmermann
Oceanography , 2011,
Abstract: We examined data on 1184 drift bottles launched by students between 2000 and 2007 from vessels of opportunity at locations scattered along the Canadian Maritimes and Greenland, supplemented with data from four bottles from historical records. The results confirm and extend observations of the geographic pattern of recoveries made in 1979–1980 using 9000 drifting cards released along the Labrador Shelf, and the track of surface currents in the North Atlantic determined during 1990–2002 using satellite-tracked drifters with drogues.
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