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Search Results: 1 - 10 of 154626 matches for " Wolfgang H. Sommer "
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Pramipexole Extended Release: A Novel Treatment Option in Parkinson's Disease
Wolfram Eisenreich,Bernd Sommer,Sebastian Hartter,Wolfgang H. Jost
Parkinson's Disease , 2010, DOI: 10.4061/2010/612619
Abstract: Pramipexole, the most commonly prescribed dopamine agonist worldwide, meanwhile serves as a reference substance for evaluation of new drugs. Based on numerous clinical data and vast experiences, efficacy and safety profiles of this non-ergoline dopamine agonist are well characterized. Since October 2009, an extended-release formulation of pramipexole has been available for symptomatic treatment of Parkinson's disease. Pramipexole administration can be cut down from three times to once a day due to the newly developed extended-release formulation. This is considerable progress in regard to minimizing pill burden and enhancing compliance. Moreover, the 24?h continuous drug release of the once-daily extended-release formulation results in fewer fluctuations in plasma concentrations over time compared to immediate-release pramipexole, given three times daily. The present study summarizes pharmacokinetics and all essential pharmacological and clinical characteristics of the extended-release formulation. In addition, it provides all study data, available so far, with regard to transition and de-novo administration of extended-release formulation for patients with Parkinson's disease. It further compares efficacy and safety data of immediate-release pramipexole with the extended-release formulation of pramipexole. 1. Introduction Parkinson’s disease is a chronic neurodegenerative illness that requires regular medication unlimited in time. Parkinsonian patients will comply much more readily to simple therapeutic regimens with fewer applications than to treatments with more frequent drug administration [1]. Pharmacologic developments of improved dopaminergic medication—which has been established as an efficient way of controlling motor symptoms in idiopathic Parkinson’s syndrome—accordingly focus on the reduction of the tablet load and on simple treatment options that are convenient for the patient. The objective is to enhance better compliance and consecutively optimum long-term outcomes by creating a more acceptable form of application—that is, an extended-release preparation that has to be taken only once a day. A prolonged-action drug permits the steady release of the active ingredient over 24 hours preventing the active concentration from continuously surging on and surging off as commonly encountered with multiple applications of the substance. An unvarying, efficient level by continuous release over 24 hours will help avoid losses during the course of the day. This is nurtured by the hope for better control of motor symptoms during the day and for less
Dopamine systems adaptation during acquisition and consolidation of a skill
Wolfgang H. Sommer,Rui M. Costa,Anita C. Hansson
Frontiers in Integrative Neuroscience , 2014, DOI: 10.3389/fnint.2014.00087
Abstract: The striatum plays a key role in motor learning. Striatal function depends strongly on dopaminergic neurotransmission, but little is known about neuroadaptions of the dopamine system during striatal learning. Using an established task that allows differentiation between acquisition and consolidation of motor learning, we here investigate D1 and D2-like receptor binding and transcriptional levels after initial and long-term training of mice. We found profound reduction in D1 binding within the dorsomedial striatum (DMS) after the first training session on the accelerated rotarod and a progressive reduction in D2-like binding within the dorsolateral striatum (DLS) after extended training. Given that similar phase- and region-specific striatal neuroadaptations have been found also during learning of complex procedural tasks including habit formation and automatic responding, the here observed neurochemical alterations are important for our understanding of neuropsychiatric disorders that show a dysbalance in the function of striatal circuits, such as in addictive behaviors.
The interrelationship between metabolic parameters in blood serum of cattle and fertility
H Sommer
Genetics Selection Evolution , 1976, DOI: 10.1186/1297-9686-8-2-295c
Abstract:
Increased mRNA Levels of TCF7L2 and MYC of the Wnt Pathway in Tg-ArcSwe Mice and Alzheimer's Disease Brain
Elin S. Blom,Yijing Wang,Lena Skoglund,Anita C. Hansson,Massimo Ubaldi,Anbarasu Lourdusamy,Wolfgang H. Sommer,Matthew Mielke,Bradley T. Hyman,Markus Heilig,Lars Lannfelt,Lars N. G. Nilsson,Martin Ingelsson
International Journal of Alzheimer's Disease , 2011, DOI: 10.4061/2011/936580
Abstract: Several components in the Wnt pathway, including β-catenin and glycogen synthase kinase 3 beta, have been implied in AD pathogenesis. Here, mRNA brain levels from five-month-old tg-ArcSwe and nontransgenic mice were compared using Affymetrix microarray analysis. With surprisingly small overall changes, Wnt signaling was the most affected pathway with altered expression of nine genes in tg-ArcSwe mice. When analyzing mRNA levels of these genes in human brain, transcription factor 7-like 2 (TCF7L2) and v-myc myelocytomatosis viral oncogene homolog (MYC), were increased in Alzheimer's disease (AD) (<.05). Furthermore, no clear differences in TCF7L2 and MYC mRNA were found in brains with frontotemporal lobar degeneration, suggesting that altered regulation of these Wnt-related genes could be specific to AD. Finally, mRNA levels of three neurogenesis markers were analyzed. Increased mRNA levels of dihydropyrimidinase-like 3 were observed in AD brain, suggesting that altered Wnt pathway regulation may signify synaptic rearrangement or neurogenesis.
The effect of success probability on test economy and self-confidence in computerized adaptive tests
JOACHIM H?USLER,MARKUS SOMMER
Psychology Science Quarterly , 2008,
Abstract: Recent research on the psychological effects of different design decisions in computerized adaptive tests indicates that the maximum-information item selection rule fails to optimize respondents’ test-taking motivation. While several recent studies have investigated psychological reactions to computerized adaptive tests using a consistently higher base success rate, little research has so far been conducted on the psychometric (primarily test reliability and bias) and psychological effects (e.g. test-taking motivation, self-confidence) of using mixtures of highly informative (p = .50) and easier items (p = .80) in the item selection process. The present paper thus compares these modifications to item selection with a classical maximum-information algorithm. In a simulation study the effect of the different item selection algorithms on measurement precision and bias in the person parameter estimates is evaluated. To do so, the item pool of the Lexical Knowledge Test, measuring crystallized intelligence and self-confidence, is used. The study indicated that modifications using base success probabilities over p = .70 lead to reduced measurement accuracy and - more seriously - a bias in the person parameter estimates for higher ability respondents. However, this was not the case for the motivator item algorithm, occasionally administering easier items as well. The second study (n = 191) thus compared the unmodified maximum-information algorithm with two motivator item algorithms, which differed with regard to the percentage of motivator items presented. The results indicate that respondents yield higher self-confidence estimates under the motivator item conditions. Furthermore, the three conditions did not differ from each other with regard to the total test duration. It can be concluded that a small number of easier motivator items is sufficient to preserve test-taking motivation throughout the test without a loss of test economy.
Nondipping in Parkinson's Disease
Sita Sommer,Billur Aral-Becher,Wolfgang Jost
Parkinson's Disease , 2011, DOI: 10.4061/2011/897586
Abstract: Objective. The aim of this study was to identify patients with Parkinson's disease who showed loss or decrease of nocturnal blood pressure fall (nondipper patients) as a marker of autonomic dysfunction. Presence or absence of orthostatic hypotension was considered to investigate whether alterations in circadian blood pressure pattern are associated with posture-related dysregulation of blood pressure. Methods. 40 patients with Parkinson's disease underwent 24-hour blood pressure monitoring. 21 patients were diagnosed with arterial hypertension and received anti-hypertensive drugs. Nondipper patients were defined as having nocturnal decrease of mean systolic and diastolic blood pressure less than 10%. Presence or absence of orthostatic hypotension was determined by Schellong's test. Results. We identified 35 nondipper patients (88%). Nondipping was detected in 20 patients with orthostatic hypotension (95%) and in 15 patients without orthostatic hypotension (79%). 18 patients with hypertensive and 22 patients with normal blood pressure values were detected. Conclusions. In conclusion 24-hour blood pressure monitoring showed a high prevalence of nondipping in 40 patients with Parkinson's disease with and without orthostatic hypotension independent of coexisting arterial hypertension and antihypertensive treatment. 24-hour blood pressure monitoring may be useful to identify non-dipping as a marker of autonomic dysfunction in patients with Parkinson's disease. 1. Introduction Parkinson’s disease is a multisystem degeneration [1]. Beside motor symptoms, and psychiatric symptoms autonomic dysfunction is a common finding in Parkinson’s disease [2]. Neuropathological studies showed the presence of Lewy bodies in central and peripheral structures involved in autonomic regulation [3–6]. Involvement of the autonomic nervous system (ANS) occurs in the early stages of the disease [2]. Cardiovascular dysautonomia, especially orthostatic hypotension, is frequently reported in Parkinson’s disease [7]. Involvement of peripheral components of the ANS can be demonstrated by MIBG scintigraphy. MIBG scintigraphy shows reduced cardiac uptake of MIBG (meta-[123I]iodobenzylguanidine) representing loss of postganglionic myocardial sympathetic nerve fibers in patients with Parkinson’s disease and autonomic failure [8]. However these findings are also seen in the early stages of the disease independent of symptoms of cardiovascular dysautonomia [9]. Further effects of autonomic cardiovascular dysfunction are demonstrated in earlier studies such as baroreceptor reflex dysfunction,
Systematic review with meta-analysis: cytokines in fibromyalgia syndrome
Nurcan ü?eyler, Winfried H?user, Claudia Sommer
BMC Musculoskeletal Disorders , 2011, DOI: 10.1186/1471-2474-12-245
Abstract: Through December 2010 we systematically reviewed the databases PubMed, MEDLINE, and PsycINFO and screened the reference lists of 22 review articles for suitable original articles. Original articles investigating cytokines in patients with FMS were included. Data were extracted by two independent authors. Differences of the cytokine levels of FMS patients and controls were summarized by standardized mean differences (SMD) using a random effects model. Study quality was assessed applying methodological scores: modified Center of Evidence Based Medicine, Newcastle-Ottawa-Scale, and Würzburg Methodological Quality Score.Twenty-five articles were included investigating 1255 FMS patients and 800 healthy controls. Data of 13/25 studies entered meta-analysis. The overall methodological quality of studies was low. The results of the majority of studies were not comparable because methods, investigated material, and investigated target cytokines differed. Systematic review of the selected 25 articles revealed that FMS patients had higher serum levels of interleukin (IL)-1 receptor antagonist, IL-6, and IL-8, and higher plasma levels of IL-8. Meta-analysis of eligible studies showed that FMS patients had higher plasma IL-6 levels compared to controls (SMD = -0.34 [-0.64, -0.03] 95% CI; p = 0.03). The majority of investigated cytokines were not different between patients and controls.The pathophysiological role of cytokines in FMS is still unclear. Studies of higher quality and with higher numbers of subjects are needed.Fibromyalgia syndrome (FMS) is a complex of symptoms that, according to the criteria of the American College of Rheumatology (ACR), is associated with chronic widespread pain and at least eleven positive tender points out of 18 [1]. Additional symptoms like fatigue, pain associated sleep disturbance, depression, or gastrointestinal disorders are frequently reported [2]. The pathophysiology of FMS is incompletely understood and although the syndrome can be charac
Long-time global radiation for Central Europe derived from ISCCP Dx data
N. Petrenz, M. Sommer,F. H. Berger
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2007,
Abstract: The global Dx dataset of the International Satellite Cloud Climatology Project (ISCCP) with a spatial resolution of about 30×30 km2 was analysed to produce spatially highly resolved long-time datasets to describe the radiation budget for Central Europe over the period of 1984–2000. The computation of shortwave and longwave radiant flux densities at top of atmosphere and at surface was based on 1D radiative transfer simulations. The simulations were carried out for all relevant atmospheric and surface conditions and the results were inserted into a look-up table. Thus, long-time calculations for all conditions and time slices of the Dx dataset could be realised. The study is focussed on the global radiation at surface. The first examination was carried out for the ISCCP D1 and the ISCCP D2 dataset. These datasets, including cloud and surface information on a different spatial scale (280×280 km2), were applied to the produced look-up table analogue to the Dx data. The calculated global radiation of the D1 and D2 dataset were compared to the Dx dataset. The differences between these datasets mainly range from 5–15 Wm 2 (2–6%) with regional peaks up to 25 Wm 2 (10%). The evaluation with the GEWEX Surface Radiation Budget (SRB) data emphasises differences between 5–25 Wm 2 (6–16%) over land areas. Deviations to an ISCCP provided flux data set vary from 0 Wm 2 in the North up to 35 Wm 2 (0–13%) in the South of Central Europe. The global radiation datasets provided by the Global Energy Balance Archive (GEBA) and the German Meteorological Service (DWD) agree well, but they are 5–25 Wm 2 (7–10%) lower than the Dx results. Annual analyses of global radiation of various regional climate models complete the study. It is figured out that the used models and methods reveal a couple of discrepancies. Especially in wintertime the results of our analysis differ to the considered models. Principally the uncertainties were caused by the determined range of values and simplifications for the computation of the radiative transfer simulation.
Optimizing technical precision of measurement in computerized psychological assessment on Windows platforms
JOACHIM H?USLER,MARKUS SOMMER,STEFAN CHROUST
Psychology Science , 2007,
Abstract: Reaction times and response latencies are required to measure a variety of ability and personality traits. If reaction times are used to measure rather elementary cognitive tasks, the inter-individual variance in the measured reaction times are usually small in the sense that the central 50 percent of a norm population range within less than 100ms. Technical measurement errors therefore have the potential to seriously affect the validity of diagnostic judgments based on such measures. Thus the target of this paper is to investigate the magnitude of possible errors of measurement due to technical reasons and to suggest ways to prevent or at least consider those in the diagnostic process.In Study I a highly precise 'artificial respondent' was applied to simulate reactions corresponding to a given percentile rank on 3 different tests (DG-Lokation CORPORAL, Alertness TAP-M, RT/S9 Vienna Test System) on 11 different computer systems. The result output of the tests was compared to the reaction times, actually provided by the artificial respondent. Results show, that there are detectable errors of measurement - depending on the hardware and software specifications of the computer system used. In the test DG-Lokation these bias caused an offset in the tests main variable of up to 20 percentile ranks.In Study II a self-calibration unit which is part of the Vienna Test System (Version 6.40) was investigated, using the same experimental setup. After calibration, the bias detected can be reduced to the magnitude of about 1 percentile rank on all computer systems tested.It thus can be concluded, that time critical computer based tests typically bear the risk of technical errors of measurement. Depending on how the test is programmed, the errors arising on some computer configurations can cause even severe changes in diagnostic judgment formation. In contrast, self-calibration proved to be an effective tool to permitting the user not only to control but also to ensure the precision of measurement, independent of the properties of the computer system he is administering his test on.
Long-time global radiation for Central Europe derived from ISCCP Dx data
N. Petrenz,M. Sommer,F. H. Berger
Atmospheric Chemistry and Physics Discussions , 2007,
Abstract: The global Dx dataset of the "International Satellite Cloud Climatology Project" (ISCCP) with a spatial resolution of about 30×30 km2 was analysed to produce spatially highly resolved long-time datasets to describe the radiation budget for Central Europe over the period of 1984–2000. The computation of shortwave and longwave radiant flux densities at top of atmosphere and at surface was based on 1-D radiative transfer simulations. The simulations were carried out for all relevant atmospheric and surface conditions and the results were inserted into a look-up table. Thus, long-time calculations for all conditions and time slices of the Dx dataset could be realised. The study is focussed on the global radiation at surface. The first examination was carried out for the ISCCP D1 and the ISCCP D2 dataset. These datasets, including cloud and surface information on a different spatial scale (280×280 km2), were applied to the produced look-up table analogue to the Dx data. The calculated global radiation of the D1 and D2 dataset were compared to the Dx dataset. The differences between these datasets mainly range from 5–15 W m 2 (2–6%) with regional peaks up to 25 W m 2 (10%). The evaluation with the GEWEX "Surface Radiation Budget" (SRB) data emphasises differ-ences between 5–25 W m 2 (6–16%) over land areas. Deviations to an ISCCP provided flux data set vary from 0 W m 2 in the North up to 35 W m 2 (0–13%) in the South of Central Europe. The global radiation datasets provided by the "Global Energy Balance Archive" (GEBA) and the "German Meteorological Service" (DWD) agree well, but they are 5–25 W m 2 (7–10%) lower than the Dx results. Annual analyses of global radiation of various regional climate models complete the study. It is figured out that the used models and methods reveal a couple of discrepancies. Especially in wintertime the results of our analysis differ to the considered models. Principally the uncer-tainties were caused by the determined range of values and simplifications for the computation of the radiative transfer simulation.
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