University of Marburg

About: University of Marburg is a education organization based out in Marburg, Germany. It is known for research contribution in the topics: Population & Virus. The organization has 23195 authors who have published 42907 publications receiving 1506069 citations. The organization is also known as: Philipps University of Marburg & Philipps-Universität.

Carbon Monoxide Oxidation by Methanogenic Bacteria

Abstract: Different species of methanogenic bacteria growing on CO2 and H2 were shown to remove CO added to the gas phase. Rates up to 0.2 μmol of CO depleted/min per 10 ml of culture containing approximately 7 mg of cells (wet weight) were observed. Methanobacterium thermoautotrophicum was selected for further study based on its ability to grow rapidly on a completely mineral medium. This species used CO as the sole energy source by disproportionating CO to CO2 and CH4 according to the following equation: 4CO + 2H2O → 1CH4 + 3CO2. However, growth was slight, and the growth rate on CO was only 1% of that observed on H2/CO2. Growth only occurred with CO concentrations in the gas phase of lower than 50%. Growth on CO agrees with the finding that cell-free extracts of M. thermoautotrophicum contained both an active factor 420 (F420)-dependent hydrogenase (7.7 μmol/min per mg of protein at 35°C) and a CO-dehydrogenating enzyme (0.2 μmol/min per mg of protein at 35°C) that catalyzed the reduction of F420 with CO. The properties of the CO-dehydrogenating enzyme are described. In addition to F420, viologen dyes were effective electron acceptors for the enzyme. The apparent Km for CO was higher than 1 mM. The reaction rate increased with increasing pH and displayed an inflection point at pH 6.7. The temperature dependence of the reaction rate followed the Arrhenius equation with an activation energy (ΔH‡) of 14.1 kcal/mol (59.0 kJ/mol). The CO dehydrogenase activity was reversibly inactivated by low concentrations of cyanide (2 μM) and was very sensitive to inactivation by oxygen. Carbon monoxide dehydrogenase of M. thermoautotrophicum exhibited several characteristic properties found for the enzyme of Clostridium pasteurianum but differed mainly in that the clostridial enzyme did not utilize F420 as the electron acceptor.

Glucose-Dependent Insulinotropic Polypeptide Is a Growth Factor for β (INS-1) Cells by Pleiotropic Signaling

Abstract: Activation of the G-protein-coupled receptor for glucose-dependent insulinotropic polypeptide facilitates insulin-release from pancreatic beta-cells. In the present study, we examined whether glucose-dependent insulinotropic polypeptide also acts as a growth factor for the beta-cell line INS-1. Here, we show that glucose-dependent insulinotropic polypeptide induced cellular proliferation synergistically with glucose between 2.5 mM and 15 mM by pleiotropic activation of signaling pathways. Glucose-dependent insulinotropic polypeptide stimulated the signaling modules of PKA/cAMP regulatory element binder, MAPK, and PI3K/protein kinase B in a glucose- and dose-dependent manner. Janus kinase 2 and signal transducer and activators of transcription 5/6 pathways were not stimulated by glucose-dependent insulinotropic polypeptide. Activation of PI3K by glucose-dependent insulinotropic polypeptide and glucose was associated with insulin receptor substrate isoforms insulin receptor substrate-2 and growth factor bound-2 associated binder-1 and PI3K isoforms p85alpha, p110alpha, p110beta, and p110gamma. Downstream of PI3K, glucose-dependent insulinotropic polypeptide-stimulated protein kinase Balpha and protein kinase Bbeta isoforms and phosphorylated glycogen synthase kinase-3, forkhead transcription factor FKHR, and p70S6K. These data indicate that glucose-dependent insulinotropic polypeptide functions synergistically with glucose as a pleiotropic growth factor for insulin-producing beta-cells, which may play a role for metabolic adaptations of insulin-producing cells during type II diabetes.

Updates on the prevalence of body dysmorphic disorder: A population-based survey

Abstract: Body dysmorphic disorder (BDD) is characterised by a preoccupation with perceived defects in one's appearance, which leads to significant distress and/or impairment. Although several studies have investigated the prevalence of BDD, many studies have methodological limitations (e.g., small sample sizes and student populations), and studies on the prevalence of BDD in the general population are limited. In the current study, 2510 individuals participated in a representative German nationwide survey. Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria for BDD and associated characteristics such as suicidality and the prevalence of plastic surgeries were examined using self-report questionnaires. The prevalence of current BDD was 1.8% (N=45). Further, individuals with BDD, relative to individuals without BDD, reported significantly more often a history of cosmetic surgery (15.6% vs. 3.0%), higher rates of suicidal ideation (31.0% vs. 3.5%) and suicide attempts due to appearance concerns (22.2% vs. 2.1%). The current findings are consistent with previous findings, indicating that self-reported BDD is a common disorder associated with significant morbidity.

Implications of Placebo and Nocebo Effects for Clinical Practice: Expert Consensus.

Abstract: Background: Placebo and nocebo effects occur in clinical or laboratory medical contexts after administration of an inert treatment or as part of active treatments and are due to psychobiological mechanisms such as expectancies of the patient. Placebo and nocebo studies have evolved from predominantly methodological research into a far-reaching interdisciplinary field that is unravelling the neurobiological, behavioural and clinical underpinnings of these phenomena in a broad variety of medical conditions. As a consequence, there is an increasing demand from health professionals to develop expert recommendations about evidence-based and ethical use of placebo and nocebo effects for clinical practice. Methods: A survey and interdisciplinary expert meeting by invitation was organized as part of the 1st Society for Interdisciplinary Placebo Studies (SIPS) conference in 2017. Twenty-nine internationally recognized placebo researchers participated. Results: There was consensus that maximizing placebo effects and minimizing nocebo effects should lead to better treatment outcomes with fewer side effects. Experts particularly agreed on the importance of informing patients about placebo and nocebo effects and training health professionals in patient-clinician communication to maximize placebo and minimize nocebo effects. Conclusions: The current paper forms a first step towards developing evidence-based and ethical recommendations about the implications of placebo and nocebo research for medical practice, based on the current state of evidence and the consensus of experts. Future research might focus on how to implement these recommendations, including how to optimize conditions for educating patients about placebo and nocebo effects and providing training for the implementation in clinical practice.

Molecular mechanisms and quantitative models of variable photosystem ii fluorescence

Abstract: *Abbreviations: Aabsj, fraction of absorption-spectrum corresponding to the jth gaussian component; c, speed of light in vacuum; Car, carotenoid; cH, enthalpic contribution in the relation between k, and klAnf; Chl, chlorophyll; CP, chlorophyll-protein complex; cw, continuous wave; DCMU, 3(3,4-dichlorophenyl)1,l -dimethylurea; AG,, freeenergydifferenceforP680*-[P680+,Phe-]; AGAnf, free energy difference for antenna* + P680*; AGP-Z, free energy difference for P680+ -+ TyrZ+; AHAnt, enthalpy difference for antenna* .+ P680*; Ei, excited state energy of ith pigment, usually energy of the first Chl singlet state; Ep,so, excited state energy of P680; F, fluorescence yield; F,, fluorescence yield in the open reaction-center state, i.e. with oxidized QA; FM, fluorescence yield in the closed reaction-center, i.e. with reduced QA; F(A,, Aem), steady-state fluorescence emission for excitation at A, and detection at kern; F,(A,,, A, t), fluorescence emission at the time t after excitation by an ultrashort laser pulse; a,, yield for exciton transfer from a closed PS I1 to its PS I1 neighbors; aF, fluorescence quantum yield; a,, yield of QA reduction in the presence of some PS I1 with reduced Q A ; a,”, yield of Q A reduction in the F, state; a,, = (FM F,)/FM; h, Planckconstant; k, Boltzmann constant; k, , (intrinsic) rate constant of primary charge separation; k/“‘ , effective rate constant of primary charge separation for RC with antenna system; k , ; rate constant of [P680+, Phe-] recombination; k2, rate constant for decay of [P680+, Phe-] by various routes besides recombination; k2,, rate constant for decay of [P680+, Phe-] by secondary charge separation; kA, decay of excited antenna states by pathways different from primary charge separation; kA-a, “gross” rate constant of QA reduction; k,, connectivity rate constant for exciton movement between PS I1 units; kdp, decay of P680* by pathways different from primary charge separation; b, rate constant for excited state decay by fluorescence, reciprocal radiative lifetime; kT, rate constant for exciton transfer from antenna to P680; kT, rate constant for exciton transfer from P680 to antenna; A,, fluorescence emission wavelength; A,,, excitation wavelength; LHC, light-harvesting pigmenuprotein complex; N,,,, number of all pigments considered in the equation (number per PS 11); OEC, oxygen-evolving complex; p, connectivity parameter of Joliot and J o l i ~ t ’ ~ ~ ; P680, primary electron donor of PS 11; p6*,,, probability for exciton to reside on P680; P680*, excited singlet state of P680; P700, primary electron donor of PS I; Phe, pheophytin a, the primary electron acceptor of PS 11; P,, ith pigment of the PS I1 antenna; p,, probability for the excited state to reside on the pigment P,; PS I, photosystem I; PS 11, photosystem 11; QA, primary quinone acceptor of PS 11; QAsingly reduced QA; Qe, secondary quinone acceptor of PS 11; Q-, fraction of PS I1 with reduced QA; qp, = (FH F)/(F, FJ, photochemical quenching coefficient; RC, reaction center; RRP, reversible radical pair model; SAnl, = -k In(NpJ, antenna entropy; T,,, radiative lifetime; T , , ~ ~ , exciton lifetime for homogeneous lattice model; exciton diffusion time, exciton movement contribution to exciton lifetime; rlrap, trapping time, charge separation contribution to exciton lifetime; reqm, exciton equilibration time, time for reaching an excited state equilibrium distribution; T,,,., mean excited state lifetime; T, temperature in K, Tyr,, Tyr,,, of the D1 protein, the secondary electron donor of PS 1