94 research outputs found

    Electrophysiological Techniques for Mitochondrial Channels

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    Cholesterol Slows down the Lateral Mobility of an Oxidized Phospholipid in a Supported Lipid Bilayer

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    We investigated the mobility and phase-partitioning of the fluorescent oxidized phospholipid analogue 1-palmitoyl-2-glutaroyl-sn-glycero-3-phospho-N-Alexa647-ethanolamine (PGPE-Alexa647) in supported lipid bilayers. Compared to the conventional phospholipid dihexadecanoylphosphoethanolamine (DHPE)-Bodipy we found consistently higher diffusion constants. The effect become dramatic when immobile obstacles were inserted into the bilayer. which essentially blocked the diffusion of DHPE-Bodipy but hardly influenced the movements of PGPE-Alexa647. In a supported lipid bilayer made of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), the differences in probe mobility leveled off with increasing cholesterol content. Using coarse-grained molecular dynamics simulations, we could ascribe this effect to increased interactions between the oxidized phospholipid and the membrane matrix, concomitant with a translation in the headgroup position of the oxidized phospholipid: at zero cholesterol content, its headgroup is shifted to the outside of the DOPC headgroup region, whereas increasing cholesterol concentrations pulls the headgroup into the bilayer plane

    Avens Root (Geum Urbanum L.) Extract Discovered by Target-Based Screening Exhibits Antidiabetic Activity in the Hen's Egg Test Model and Drosophila melanogaster

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    Medicinal plant extracts are becoming increasingly important as an alternative for traditional drugs against diabetes mellitus (DM). For this reason, we initialized a target-based screening of 111 root extracts from an open access plant extract library (PECKISH) by ascertaining their in-vitro inhibitory efficacy on α-glucosidase. The two most active extracts Geum urbanum L. (roseroot) and Rhodiola rosea L. (avens root) were further tested for their antidiabetic activities in terms of their impact on different regulatory key points of glucose homeostasis. To this end, various enzyme- and cell culture-based in-vitro assays were employed including the determination of sodium-dependent glucose transporter 1 (SGLT1) activity in Caco-2 monolayers by Ussing chambers and of glucose transporter 4 (GLUT4) translocation in a GFP-reporter cell line. Subsequently, the antidiabetic potential of the root extracts were further evaluated in in-vivo models, namely hen's eggs test and the fruit fly Drosophila melanogaster. Avens root extract was found to be a more potent inhibitor of the enzymes α-glucosidase and dipeptidyl peptidase-4 (DPP4) than roseroot extract. Most importantly, only avens root extract exhibited antidiabetic activity in the two in-vivo models eliciting a reduced blood glucose level in the in-ovo model and a decline of the triglyceride level in a dietary starch-induced D. melanogaster obesity model. Analyses of the polyphenolic composition of the avens root extract by HPLC revealed a high content of ellagic acid and its derivatives as well as ellagitannins such as pedunculagin, stenophyllanin, stachyurin, casuarinin and gemin A. In conclusion, avens root extract represents a promising medicinal plant that should be considered in further in-vivo studies on hyperglycemia in laboratory rodents and humans

    Mrs2p Forms a High Conductance Mg2+ Selective Channel in Mitochondria

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    Members of the CorA-Mrs2-Alr1 superfamily of Mg2+ transporters are ubiquitous among pro- and eukaryotes. The crystal structure of a bacterial CorA protein has recently been solved, but the mode of ion transport of this protein family remained obscure. Using single channel patch clamping we unequivocally show here that the mitochondrial Mrs2 protein forms a Mg2+-selective channel of high conductance (155 pS). It has an open probability of ∌60% in the absence of Mg2+ at the matrix site, which decreases to ∌20% in its presence. With a lower conductance (∌45 pS) the Mrs2 channel is also permeable for Ni2+, whereas no permeability has been observed for either Ca2+, Mn2+, or Co2+. Mutational changes in key domains of Mrs2p are shown either to abolish its Mg2+ transport or to change its characteristics toward more open and partly deregulated states. We conclude that Mrs2p forms a high conductance Mg2+ selective channel that controls Mg2+ influx into mitochondria by an intrinsic negative feedback mechanism

    Evidence from Studies with Heat-Stressed Caco-2 Cells, C. elegans and Growing Broilers

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    Climatic changes and heat stress have become a great challenge in the livestock industry, negatively affecting, in particular, poultry feed intake and intestinal barrier malfunction. Recently, phytogenic feed additives were applied to reduce heat stress effects on animal farming. Here, we investigated the effects of ginseng extract using various in vitro and in vivo experiments. Quantitative real-time PCR, transepithelial electrical resistance measurements and survival assays under heat stress conditions were carried out in various model systems, including Caco-2 cells, Caenorhabditis elegans and jejunum samples of broilers. Under heat stress conditions, ginseng treatment lowered the expression of HSPA1A (Caco-2) and the heat shock protein genes hsp-1 and hsp-16.2 (both in C. elegans), while all three of the tested genes encoding tight junction proteins, CLDN3, OCLN and CLDN1 (Caco-2), were upregulated. In addition, we observed prolonged survival under heat stress in Caenorhabditis elegans, and a better performance of growing ginseng-fed broilers by the increased gene expression of selected heat shock and tight junction proteins. The presence of ginseng extract resulted in a reduced decrease in transepithelial resistance under heat shock conditions. Finally, LC-MS analysis was performed to quantitate the most prominent ginsenosides in the extract used for this study, being Re, Rg1, Rc, Rb2 and Rd. In conclusion, ginseng extract was found to be a suitable feed additive in animal nutrition to reduce the negative physiological effects caused by heat stress. View Full-Tex

    There Is a Clinical Need to Consider the Physical Activity: Sedentary Pattern in Children with Obesity – Position Paper of the European Childhood Obesity Group

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    &lt;b&gt;&lt;i&gt;Introduction:&lt;/i&gt;&lt;/b&gt; While international prevention guidelines recently advocated, in addition to moderate and vigorous physical activity (MVPA) guidelines, for a minimization of sedentary (SED) time, recommendations remain to be developed for youths with obesity. &lt;b&gt;&lt;i&gt;Methods:&lt;/i&gt;&lt;/b&gt; A literature search was conducted in PubMed, the Cochrane Library, plus the reference lists of selected articles for relevant publications in English, including original papers, systematic reviews, and meta-analyses, with search terms “sedentary behaviors” or “sedentary time” or “screen time” AND “children” or “adolescents” AND “obesity” or “adiposity” or “cardiometabolic risk” or “cardiometabolic disease.” The results were summarized as a narrative review and presented to the scientific board of the European Childhood Obesity Group (ECOG), who then discussed their implication in clinical practice and proposed the position outlined in this paper. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; SED and screen times are associated with adiposity and cardiometabolic risks, independently of youths’ physical activity (PA) level. Besides considering MVPA and SED times as separate variables, comprehensive studies have questioned the impact of different patterns of MVPA and SED levels. Although lower body adiposity and better cardiometabolic health are achieved among those with desirable movement behavior patterns (i.e., more MVPA/less SED or active/not SED), youths with intermediate patterns (i.e., high MVPA/high SED and low MVPA/low SED, or active/SED and inactive/not SED) have been found to be associated with intermediate risks. &lt;b&gt;&lt;i&gt;Conclusion:&lt;/i&gt;&lt;/b&gt; There is a need to decrease SED behaviors irrespective of MVPA and to consider PA-SED patterns in youth with obesity. The ECOG encourages anti-obesity strategies targeting both PA and SED behaviors to support the shift from long periods of SED time, especially screen time, to daily routines incorporating bouts of PA. Stepwise or sequential approaches to movement behavior counseling might start with targeting SED at first to decrease cardiometabolic risks when implementing MVPA is not yet possible. </jats:p