Modulation des kanonischen Wnt/[Beta]-Catenin-Signalweges in der Helicobacter pylori-Infektion

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2010

Mechanismen der A[beta]-induzierten neuronalen Dysfunktion

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2010

Beeinflussung von Lokomotion und kontextueller Furcht durch die Unterbrechung des viszeralen Feedback mittels peripherer [beta]1-adrenerger Rezeptorblockade in C57BL/6JOlaHsd-Mäusen

Magdeburg, Univ., Medizin. Fakultät, Diss., 2007

Effects of deoxycholic acids and urodeoxycholic acids on cancerogenic progression in Barrett`s Esophagus

Magdeburg, Univ., Med. Fak., Diss., 2014

Einfluss von Deoxynivalenol und E.coli-Lipopolysaccharid auf die Expression von ZO-1 und [beta]-Catenin im Dünndarm des Schweins

Magdeburg, Univ., Med. Fak., Diss., 2014

Effects of deoxycholic acids and urodeoxycholic acids on cancerogenic progression in Barrett`s Esophagus

Magdeburg, Univ., Med. Fak., Diss., 2014

Efeito do ácido beta indolacético e de cloreto de cálcio no enraizamento de estacas da amoreira (Morus alba, L., var. Catânia 1) em estufim, plantadas na posição invertida

Os autores apresentam neste trabalho os resultados de experimento de enraizamento de estacas de amoreira (Morus alba L., var. Catânia 1) com o emprego de hormônio vegetal sintético, ácido Beta indolacético (100 ppm) e soluções de cloreto de cálcio (2,5 5,00 10,00 iônios Ca++/1.000 ml) . Aquela variedade, uma das mais produtiva em folhas que por sua vez se apresentam mais ricas em elementos nutritivos à alimentação do bicho-da-seda (Bombyx mori L.), dificilmente se propaga pela estaquia natural, o que impede seu cultivo no sistema de "cepo". Depois das estacas da amoreira (Morus alba L., var. Catânia 1) terem sido preparadas e tratadas durante 24 horas em vasilhames de polietileno, foram no dia 24 de outubro de 1973, plantadas na posição invertida em substrato ,areia grossa lavada) contido em estufim. A retirada das estacas e consequentemente a conclusão do experimento, verificou-se 110 dias após seu plantio.

Wirkung von 17-[beta]-Estradiol auf mitochondriale Funktionen

Magdeburg, Univ., Med. Fak., Diss., 2015

Estimulació beta-adrenèrgica en la síndrome del destret respiratori agut (SDRA)

Estudi elaborat a partir d’una estada al Royal Brompton Hospital, Londres, Regne Unit, durant octubre i novembre del 2006.Els beneficis de la estimulació beta-adrenèrgica en pacients amb lesió pulmonar aguda (LPA) són coneguts, però no es disposa de dades sobre el possible efecte antiinflamatori. El condensat d'aire exhalat (CAE) és una tècnica no-invasiva de recollida de mostres del tracte respiratori inferior, podent ser útil en la monitorització de patologies respiratòries. S’ha usat marcadors biològics en el CAE de pacients ventilats mecànicament amb LPA per estudiar el possible efecte antiinflamatori que el salbutamol hi podria exercir. El CAE va ser recollit abans i després de l'administració de salbutamol inahalat. Inmediatament després es va mesurar la conductivitat i el pH abans i després de la desgasificació amb heli. Es va mesurar la concentració de nitrits i nitrats. Les mostres varen ser liofilitzades i guardades a -80ºC. La concentració de leucotriè B4 es va mesurar després de la reconstitució de la mostra. Els resultats s'expressen com a mitjana (error estàndard de la mostra). No s'han detectat diferències entre els valors de CAE basals dels pacients amb LPA i els de referència de la població sana de Barcelona. Es conclou doncs que el CAE és una tècnica no invasiva que pot ser usada en la monitorització de paceints ventilats mecànicament. El salbutamol inhalat incrementa de manera significativa el pH del CAE dels paceints amb LPA, tot i que un efecte directe de la inhalació de slabutamol no pot ser desestimat.

T-cell receptor V beta use predicts reactivity and tolerance to Mlsa-encoded antigens.

T lymphocytes reactive with the product of the Mlsa-allele of the minor lymphocyte stimulating (Mls) locus use a predominant T-cell receptor beta-chain variable gene segment (V beta 6). Such V beta 6-bearing T cells are selectively eliminated in the thymus of Mlsa-bearing mice, consistent with a model in which tolerance to self antigens is achieved by clonal deletion.

Insulin secretion is regulated by the glucose-dependent production of islet beta cell macrophage migration inhibitory factor.

Macrophage migration inhibitory factor (MIF), originally identified as a cytokine secreted by T lymphocytes, was found recently to be both a pituitary hormone and a mediator released by immune cells in response to glucocorticoid stimulation. We report here that the insulin-secreting beta cell of the islets of Langerhans expresses MIF and that its production is regulated by glucose in a time- and concentration-dependent manner. MIF and insulin colocalize by immunocytochemistry within the secretory granules of the pancreatic islet beta cells, and once released, MIF appears to regulate insulin release in an autocrine fashion. In perifusion studies performed with isolated rat islets, immunoneutralization of MIF reduced the first and second phase of the glucose-induced insulin secretion response by 39% and 31%, respectively. Conversely, exogenously added recombinant MIF was found to potentiate insulin release. Constitutive expression of MIF antisense RNA in the insulin-secreting INS-1 cell line inhibited MIF protein synthesis and decreased significantly glucose-induced insulin release. MIF is therefore a glucose-dependent, islet cell product that regulates insulin secretion in a positive manner and may play an important role in carbohydrate metabolism.

Structure-function relationships of the alpha1b-adrenergic receptor.

The alpha1b-adrenergic receptor (AR) is a member of the large superfamily of seven transmembrane domain (TMD) G protein-coupled receptors (GPCR). Combining site-directed mutagenesis of the alpha1b-AR with computational simulations of receptor dynamics, we have explored the conformational changes underlying the process of receptor activation, i.e. the transition between the inactive and active states. Our findings suggest that the structural constraint stabilizing the alpha1b-AR in the inactive form is a network of H-bonding interactions amongst conserved residues forming a polar pocket and R143 of the DRY sequence at the end of TMDIII. We have recently reported that point mutations of D142, of the DRY sequence and of A293 in the distal portion of the third intracellular loop resulted in ligand-independent (constitutive) activation of the alpha1b-AR. These constitutively activating mutations could induce perturbations resulting in the shift of R143 out of the polar pocket. The main role of R143 may be to mediate receptor activation by triggering the exposure of several basic amino acids of the intracellular loops towards the G protein. Our investigation has been extended also to the biochemical events involved in the desensitization process of alpha1b-AR. Our results indicate that immediately following agonist-induced activation, the alpha1b-AR can undergo rapid agonist-induced phosphorylation and desensitization. Different members of the G protein coupled receptor kinase family can play a role in agonist-induced regulation of the alpha1b-AR. In addition, constitutively active alpha1b-AR mutants display different phosphorylation and internalization features. The future goal is to further elucidate the molecular mechanism underlying the complex equilibrium between activation and inactivation of the alpha1b-AR and its regulation by pharmacological substances. These findings can help to elucidate the mechanism of action of various agents displaying properties of agonists or inverse agonists at the adrenergic system.

Liprin (beta)1 is highly expressed in lymphatic vasculature and is important for lymphatic vessel integrity.

The lymphatic vasculature is important for the regulation of tissue fluid homeostasis, immune response, and lipid absorption, and the development of in vitro models should allow for a better understanding of the mechanisms regulating lymphatic vascular growth, repair, and function. Here we report isolation and characterization of lymphatic endothelial cells from human intestine and show that intestinal lymphatic endothelial cells have a related but distinct gene expression profile from human dermal lymphatic endothelial cells. Furthermore, we identify liprin beta1, a member of the family of LAR transmembrane tyrosine phosphatase-interacting proteins, as highly expressed in intestinal lymphatic endothelial cells in vitro and lymphatic vasculature in vivo, and show that it plays an important role in the maintenance of lymphatic vessel integrity in Xenopus tadpoles.

Effects of infused amino acids on glucose production and utilization in healthy human subjects.

Amino acids have been reported to increase endogenous glucose production in normal human subjects during hyperinsulinemia: however, controversy exists as to whether insulin-mediated glucose disposal is inhibited under these conditions. The effect of an amino acid infusion on glucose oxidation rate has so far not been determined. Substrate oxidation rates, endogenous glucose production, and [13C]glucose synthesis from [13C]bicarbonate were measured in six normal human subjects during sequential infusions of exogenous glucose and exogenous glucose with (n = 5) or without (n = 5) exogenous amino acids. Amino acids increased endogenous glucose production by 84% and [13C]glucose synthesis by 235%. Glucose oxidation estimated from indirect calorimetry decreased slightly after amino acids, but glucose oxidation estimated from [13C]glucose-13CO2 data was increased by 14%. It is concluded that gluconeogenesis is the major pathway of amino acid degradation. During amino acid administration, indirect calorimetry underestimates the true rate of glucose oxidation, whereas glucose oxidation calculated from the 13C enrichment of expired CO2 during [U-13C]glucose infusion does not. A slight stimulation of glucose oxidation during amino acid infusion, concomitant with an increased plasma insulin concentration, indicates that amino acids do not inhibit glucose oxidation.

Peroxisomal beta-oxidation--a metabolic pathway with multiple functions.

Fatty acid degradation in most organisms occurs primarily via the beta-oxidation cycle. In mammals, beta-oxidation occurs in both mitochondria and peroxisomes, whereas plants and most fungi harbor the beta-oxidation cycle only in the peroxisomes. Although several of the enzymes participating in this pathway in both organelles are similar, some distinct physiological roles have been uncovered. Recent advances in the structural elucidation of numerous mammalian and yeast enzymes involved in beta-oxidation have shed light on the basis of the substrate specificity for several of them. Of particular interest is the structural organization and function of the type 1 and 2 multifunctional enzyme (MFE-1 and MFE-2), two enzymes evolutionarily distant yet catalyzing the same overall enzymatic reactions but via opposite stereochemistry. New data on the physiological roles of the various enzymes participating in beta-oxidation have been gathered through the analysis of knockout mutants in plants, yeast and animals, as well as by the use of polyhydroxyalkanoate synthesis from beta-oxidation intermediates as a tool to study carbon flux through the pathway. In plants, both forward and reverse genetics performed on the model plant Arabidopsis thaliana have revealed novel roles for beta-oxidation in the germination process that is independent of the generation of carbohydrates for growth, as well as in embryo and flower development, and the generation of the phytohormone indole-3-acetic acid and the signal molecule jasmonic acid.