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Search Results: 1 - 10 of 44850 matches for " Michael Linnebank "
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Haplotype analysis of the 5,10-methylenetetrahydrofolate reductase (MTHFR) c.1298A>C (E429A) polymorphism
Alexander Semmler, Susanna Moskau, Holger Lutz, Peter Meyer, Michael Linnebank
BMC Research Notes , 2011, DOI: 10.1186/1756-0500-4-439
Abstract: Haplotype construction revealed that the C-allele of MTHFR c.1298A>C was more frequently observed in cis with c.129T, IVS2 533A, c.677C, c.1068T, and IVS10 262 G than expected from normal distribution. Estimation of the most recent common ancestor with the DMLE + 2.3 program resulted in an estimated age of approximately 36,660 years of the MTHFR c.1298C allele.Given that the era from 30,000 to 40,000 years ago is characterised by the spread of modern humans in Europe and that the prevalence of the MTHFR c.1298C allele is significantly higher in Central Europe in comparison to African populations, a selective advantage of MTHFR c.1298C could be assumed, e. g. by adaption to changes in the nutritional environment. The known founder ancestry of the T allele of MTHFR c.677C>T allele, together with the present data suggests that the MTHFR mutant alleles c.677T and 1298C arose from two independent ancestral alleles, that both confer a selective advantage.The monomeric enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR, EC 607093, OMIM 236250) catalyzes the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate (5-MTHF). 5-MTHF is a methyl group donor for the remethylation of homocysteine to methionine. The T-allele of the MTHFR polymorphism c.677C>T (A222V, rs1801133) is associated with reduced MTHFR activity and, thus with an increased total plasma homocysteine level [1]. The frequency of the T-allele of MTHFR c.677C>T differs between ethnic groups and ranges from 6-10% in African countries [2,3] to more than 17% in Caucasians in North America [1,4,5] and more than 50% in Mexican populations [3]. In the literature, the presence of the T-allele has been associated with cardiovascular and cerebrovascular diseases, venous thrombosis, neural tube defects and various cancers [6]. It was hypothesized that this might be due to increased plasma homocysteine levels in carriers of the MTHFR c.677T allele [7]. In addition, the allele's function for DNA synthesi
Fatigue and Sleep-Disordered Breathing in Multiple Sclerosis: A Clinically Relevant Association?
Ulf Kallweit,Christian R. Baumann,Michael Harzheim,Hildegard Hidalgo,Dieter P?hlau,Claudio L. Bassetti,Michael Linnebank,Philipp O. Valko
Multiple Sclerosis International , 2013, DOI: 10.1155/2013/286581
Abstract: Background. Fatigue in patients with multiple sclerosis (MS) is highly prevalent and severely impacts quality of life. Recent studies suggested that sleep-disordered breathing (SDB) significantly contributes to fatigue in MS. Study Objective. To evaluate the importance of routine respirography in MS patients with severe fatigue and to explore the effects of treatment with continuous positive airway pressure (CPAP). Patients and Methods. We prospectively assessed the presence of severe fatigue, as defined by a score of ≥5.0 on the Fatigue Severity Scale (FSS), in 258 consecutive MS patients. Ninety-seven patients (38%) suffered from severe fatigue, whereof 69 underwent overnight respirography. Results. We diagnosed SDB in 28 patients (41%). Male sex was the only independent associate of SDB severity ( ). CPAP therapy in 6 patients was associated with a significant reduction of FSS scores ( versus , ), but the scores remained pathological (≥4.0) in all patients. Conclusion. Respirography in MS patients with severe fatigue should be considered in daily medical practice, because SDB frequency is high and CPAP therapy reduces fatigue severity. However, future work is needed to understand the real impact of CPAP therapy on quality of life in this patient group. 1. Introduction Although fatigue has been increasingly recognized over the past two decades as one of the most frequent and most debilitating symptoms in patients with MS, there are still no insights into its neurobiological mechanisms, and current treatment options are highly frustrating [1–4]. In clinical practice, MS patients complaining about fatigue are usually first scrutinized for additional and potentially treatable comorbidities, such as depression, pain, anemia, or sleep-wake disturbances [5]. If there is no such cause of fatigue, the patient is considered to suffer from “MS-related fatigue,” that is, a disease-inherent symptom related to the underlying neuroimmunological and neurodegenerative processes, and off-label symptomatic treatment with stimulants of the central nervous system may be recommended [3]. Recently, the need to search for sleep-wake disorders in MS patients has been reemphasized, as several groups observed a significant correlation with fatigue [6–10]. Specifically, sleep-disordered breathing (SDB) has been proposed as a potential risk factor for fatigue in MS. In the last year, a cross-sectional study in 48 MS patients suggested a predisposition for SDB [11], and two studies found that severe fatigue in MS was significantly associated with SDB and respiratory-related
Plasma folate levels are associated with the lipoprotein profile: a retrospective database analysis
Alexander Semmler, Susanna Moskau, Andreas Grigull, Susan Farmand, Thomas Klockgether, Yvo Smulders, Henk Blom, Bernd Zur, Birgit Stoffel-Wagner, Michael Linnebank
Nutrition Journal , 2010, DOI: 10.1186/1475-2891-9-31
Abstract: In a retrospective single center approach, we analyzed the laboratory database (2003-2006) of the University Hospital Bonn, Germany, including 1743 individuals, in whom vitamin B12, folate and at least one lipoprotein parameter had been determined by linear multilogistic regression.Higher folate serum levels were associated with lower serum levels of low density lipoprotein cholesterol (LDL-C; Beta = -0.164; p < 0.001), higher levels of high density lipoprotein cholesterol (HDL-C; Beta = 0.094; p = 0.021 for trend) and a lower LDL-C-C/HDL-C-ratio (Beta = -0.210; p < 0.001). Using ANOVA, we additionally compared the individuals of the highest with those of the lowest quartile of folate. Individuals of the highest folate quartile had higher levels of HDL-C (1.42 ± 0.44 mmol/l vs. 1.26 ± 0.47 mmol/l; p = 0.005), lower levels of LDL-C (3.21 ± 1.04 mmol/l vs. 3.67 ± 1.10 mmol/l; p = 0.001) and a lower LDL-C/HDL-C- ratio (2.47 ± 1.18 vs. 3.77 ± 5.29; p = 0.002). Vitamin B12 was not associated with the lipoprotein profile.In our study sample, high folate levels were associated with a favorable lipoprotein profile. A reconfirmation of these results in a different study population with a well defined status of health, diet and medication is warranted.Increased homocysteine (Hcys) levels and altered plasma lipid levels are generally considered to be independent risk factors for the development of cardiovascular disease (CVD). However, lifestyle and nutrition may cause a coincidence of the homocysteine and lipoprotein status. Although of potential clinical and scientific relevance such a relationship is not generally acknowledged.Recent studies have already described an inverse relationship between folate and high-density lipoprotein cholesterol (HDL-C) levels and low folate levels have therefore been suggested to be a cardiovascular risk factor and that the subjects with lower folate levels should be recommended for dietary folic acid supplementation to HDL-C levels [1,2].Sev
A Possible Genetic Link between MTHFR Genotype and Smoking Behavior
Michael Linnebank, Susanna Moskau, Alexander Semmler, Barbara Hoefgen, Gisela Bopp, Ulf Kallweit, Wolfgang Maier, Christian G. Schütz, Ullrich Wüllner
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0053322
Abstract: Background Hyperhomocysteinemia is an independent risk factor for stroke and other vascular events. The variant methylenetetrahydrofolate reductase (MTHFR) C677T is associated with elevated homocysteine levels, cardiovascular disease and stroke, which supports a causal relationship between hyperhomocysteinemia and vascular disease. However, MTHFR variants have also been reported to be associated with smoking behavior, which could be an important confounder. Methodology/Principal Findings We analyzed the MTHFR variants C677T and A1298C in two independent samples of 525 and 535 individuals, respectively. 21% of the non-smokers, but only 12% of the smokers were homozygous carriers of both MTHFR wildtype alleles, i.e. 677CC and 1298AA (Chi2 = 15.8; p<0.001; binary regression). Plasma homocysteine levels were higher in smokers (13.9±4.1 μmol/L) than in non-smokers (12.6±4.0 μmol/L; F = 11.4; p = 0.001; ANOVA). Smoking MTHFR 677TT individuals had the highest plasma homocysteine levels (16.2±5.2 μmol/L), non-smoking 677CC individuals had the lowest (12.2±13.6 μmol/L). Conclusions/Significance In our study samples, MTHFR variants and smoking behaviour were associated with homocysteine plasma levels. In addition, the MTHFR variants were associated with smoking behaviour. Such an association may be a relevant confounder between MTHFR variants, homocysteine plasma levels and vascular diseases.
Does Child Maltreatment Mediate Family Environment and Psychological Well-Being?  [PDF]
Michael Galea
Psychology (PSYCH) , 2010, DOI: 10.4236/psych.2010.12019
Abstract: This study tried to establish if childhood maltreatment mediates the established relationship between family environ-ment and psychological well-being, in a sample of Maltese university students (N = 312). However, our analysis sug-gested partial mediation only. Moreover, results indicated that abusive families are less loving, socially integrated, organized, and more conflicted. Family environment contributed positively, albeit limited, to cognitive well-being after controlling for child abuse history. In particular, cohesion, do add unique variance to subjective well-being, after controlling for child abuse. This study replicates classic research on the important role that family environment plays in children’s holistic development.
Blended Change Management: Concept and Empirical Investigation of Blending Patterns  [PDF]
Michael REISS
iBusiness (IB) , 2009, DOI: 10.4236/ib.2009.12008
Abstract: In coping with the challenges of revolutionary or evolutionary change processes, change managers do not rely on single tools but on toolboxes containing several domains of tools. The impact of toolboxes on change performance depends both on the complementary inter-domain mix and the intra-domain blending of tools. The patterns of blending are investigated both conceptually and empirically with respect to scope, diversity and coupling of tools. Survey results indicate that blending practices are predominantly determined by rational tool evaluation and by task context.
Single Wire Electrical System  [PDF]
Michael Bank
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.411092
Abstract: The purpose of this article is to remind of the past and present problems of creating single wire electrical systems. This article presents a new one wire electrical transmission system named B-Line which uses one line only and does not use ground as a second line. The proposed method is to work on all frequencies and on all communication systems including DC systems. It also proposes to work on the concept of the single-pole signal source and single-pole signal load. It illustrates the possibility of cutting the cost of electrical lines and several other advantages in the fields of high frequency communication lines and antennas.
Relationship of nine constants  [PDF]
Michael Snyder
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.59117
Abstract:

Through the process of trial and error, four unitless equations made up of nine constants have been found with exact answers. The related constants are the Speed of Light [1], the Planck constant [2], Wien’s displacement constant [3], Avogadro’s number [4], the universal Gravity constant [5], the Ampere constant [6], the Faraday constant [7], the Gas constant [8] and Apery’s constant [9].

The Counterfeit Electronics Problem  [PDF]
Michael Pecht
Open Journal of Social Sciences (JSS) , 2013, DOI: 10.4236/jss.2013.17003
Abstract:

Counterfeit electronics have been reported in a wide range of products, including computers, telecommunications equipment, automobiles, avionics and military systems. Counterfeit electronic products include everything from very inexpensive capacitors and resistors to costly microprocessors to servers. This paper describes the counterfeit electronic products problem, and discusses the implication of counterfeit electronics on the electronic supply chain. We then present counterfeit detection and prevention techniques for electronics.

Irrationality Re-Examined: A Few Comments on the Conjunction Fallacy  [PDF]
Michael Aristidou
Open Journal of Philosophy (OJPP) , 2013, DOI: 10.4236/ojpp.2013.32050
Abstract: In this paper, I argue that the probability model used to infer irrationality for the subjects in the famous Linda problem is not appropriate, and I suggest different approaches based on fuzzy reasoning models. My line of argument is two-fold: 1) If the term “probability” is understood properly (mathematically), then the experimenters used the wrong model. 2) If the term “probability” is understood casually (non- mathematically), then alternative models perhaps should be used to justify the subjects’ responses. The objective is to experiment with new ways of looking at irrationality and raise a discussion regarding the relation between irrationality, reasoning errors and logical models that are used as frameworks to study irrationality.
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