Measurement of Compton Scattering at MAMI for the Extraction of the Electric and Magnetic Polarizabilities of the Proton.

A precise measurement of the differential cross sections dσ/dΩ and the linearly polarized photon beam asymmetry Σ_{3} for Compton scattering on the proton below pion threshold has been performed with a tagged photon beam and almost 4π detector at the Mainz Microtron. The incident photons were produced by the recently upgraded Glasgow-Mainz photon tagging facility and impinged on a cryogenic liquid hydrogen target, with the scattered photons detected in the Crystal Ball/TAPS setup. Using the highest statistics Compton scattering data ever measured on the proton along with two effective field theories (both covariant baryon and heavy-baryon) and one fixed-t dispersion relation model, constraining the fits with the Baldin sum rule, we have obtained the proton electric and magnetic polarizabilities with unprecedented precision: α_{E1}=10.99±0.16±0.47±0.17±0.34, ß_{M1}=3.14±0.21±0.24±0.20±0.35; in units of 10^{-4} fm^{3} where the errors are statistical, systematic, spin polarizability dependent, and model dependent.

Helicity-Dependent Cross Sections for the Photoproduction of π

The double-polarization observable E and helicity-dependent cross sections σ_{1/2}, σ_{3/2} have been measured for the photoproduction of π^{0} pairs off quasifree protons and neutrons at the Mainz MAMI accelerator with the Crystal Ball/TAPS setup. A circularly polarized photon beam was produced by bremsstrahlung from longitudinally polarized electrons and impinged on a longitudinally polarized deuterated butanol target. The reaction products were detected with an almost 4π covering calorimeter. The results reveal for the first time the helicity- and isospin-dependent structure of the γN→Nπ^{0}π^{0} reaction. They are compared to predictions from reaction models in view of nucleon resonance contributions and also to a refit of one model that predicted results for the proton and for the neutron target. The comparison of the prediction and the refit demonstrates the large impact of the new data.

Signatures of the d

We report a measurement of the spin polarization of the recoiling neutron in deuterium photodisintegration, utilizing a new large acceptance polarimeter within the Crystal Ball at MAMI. The measured photon energy range of 300-700 MeV provides the first measurement of recoil neutron polarization at photon energies where the quark substructure of the deuteron plays a role, thereby providing important new constraints on photodisintegration mechanisms. A very high neutron polarization in a narrow structure centered around E_{γ}∼570 MeV is observed, which is inconsistent with current theoretical predictions employing nucleon resonance degrees of freedom. A Legendre polynomial decomposition suggests this behavior could be related to the excitation of the d^{*}(2380) hexaquark.

Study of η and η' Photoproduction at MAMI.

The reactions γp→ηp and γp→η^{'}p are measured from their thresholds up to the center-of-mass energy W=1.96 GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full production-angle coverage. A strong cusp is observed in the total cross section for η photoproduction at the energies in the vicinity of the η^{'} threshold, W=1896 MeV (E_{γ}=1447 MeV). Within the framework of a revised ηMAID isobar model, the cusp, in connection with a steep rise of the η^{'} total cross section from its threshold, can only be explained by a strong coupling of the poorly known N(1895)1/2^{-} state to both ηp and η^{'}p. Including the new high-accuracy results in the ηMAID fit to available η and η^{'} photoproduction data allows the determination of the N(1895)1/2^{-} properties.

Insight into the Narrow Structure in η Photoproduction on the Neutron from Helicity-Dependent Cross Sections.

The double polarization observable E and the helicity dependent cross sections σ_{1/2} and σ_{3/2} were measured for η photoproduction from quasifree protons and neutrons. The circularly polarized tagged photon beam of the A2 experiment at the Mainz MAMI accelerator was used in combination with a longitudinally polarized deuterated butanol target. The almost 4π detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from η→2γ and η→3π^{0}. The results show that the narrow structure previously observed in η photoproduction from the neutron is only apparent in σ_{1/2} and hence, most likely related to a spin-1/2 amplitude. Nucleon resonances that contribute to this partial wave in η production are only N 1/2^{-} (S_{11}) and N 1/2^{+} (P_{11}). Furthermore, the extracted Legendre coefficients of the angular distributions for σ_{1/2} are in good agreement with recent reaction model predictions assuming a narrow resonance in the P_{11} wave as the origin of this structure.

N(1520) 3/2(-) helicity amplitudes from an energy-independent multipole analysis based on new polarization data on photoproduction of neutral pions.

New data on the polarization observables T, P, and H for the reaction γp→pπ(0) are reported. The results are extracted from azimuthal asymmetries when a transversely polarized butanol target and a linearly polarized photon beam are used. The data were taken at the Bonn electron stretcher accelerator ELSA using the CBELSA/TAPS detector. These and earlier data are used to perform a truncated energy-independent partial wave analysis in sliced-energy bins. This energy-independent analysis is compared to the results from energy-dependent partial wave analyses.

Photoproduction of π0 mesons off neutrons in the nucleon resonance region.

Precise angular distributions have been measured for the first time for the photoproduction of π0 mesons off neutrons bound in the deuteron. The effects from nuclear Fermi motion have been eliminated by a complete kinematic reconstruction of the final state. The influence of final-state-interaction effects has been estimated by a comparison of the reaction cross section for quasifree protons bound in the deuteron to the results for free protons and then applied as a correction to the quasifree neutron data. The experiment was performed at the tagged photon facility of the Mainz Microtron MAMI with the Crystal Ball and TAPS detector setup for incident photon energies between 0.45 and 1.4 GeV. The results are compared to the predictions from reaction models and partial-wave analyses based on data from other isospin channels. The model predictions show large discrepancies among each other and the present data will provide much tighter constraints. This is demonstrated by the results of a new analysis in the framework of the Bonn-Gatchina coupled-channel analysis which included the present data.

Narrow structure in the excitation function of η photoproduction off the neutron.

The photoproduction of η mesons off nucleons bound in 2H and 3He has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility. Decay photons from the η→2γ and η→3π0 decays and the recoil nucleons were detected with an almost 4π electromagnetic calorimeter combining the Crystal Ball and TAPS detectors. The data from both targets are of excellent statistical quality and show a narrow structure in the excitation function of γn→nη. The results from the two measurements are consistent, taking into account the expected effects from nuclear Fermi motion. The best estimates for position and intrinsic width of the structure are W=(1670±5) MeV and Γ=(30±15) MeV. For the first time precise results for the angular dependence of this structure have been extracted.

[Diagnosis and treatment of iron deficiency and anaemia in inflammatory bowel diseases. Consensus of the Austrian IBD Working Party]. / Diagnose und Behandlung von Eisenmangel und Anämie bei chronisch entzündlichen Darmerkrankungen. Konsensus der österreichischen Arbeitsgruppe für CED.

Iron deficiency with and without anaemia is a common burden of patients with inflammatory bowel diseases (IBD) and has considerable impact on their quality of life and the ability to perform. The IBD working group of the Austrian Society of Gastroenterology and Hepatology developed five consensus statements on the following topics: (i) diagnosis of iron deficiency and (ii) anaemia, (iii) screening of iron deficiency, (iv) treatment of iron deficiency and (v) therapeutic goals. The clinical importance of intravenous iron replacement therapy in IBD with regard to effectiveness and compliance was discussed.

[Infliximab therapy for Crohn's disease - a practical guideline: actualised consensus of the working group for chronic inflammatory bowel diseases of the Austrian Society for Gastroenterology and Hepatology]. / Infliximab in der Therapie des Morbus Crohn - ein praktischer Leitfaden: aktualisierter ÖGGH-Konsensus der Arbeitsgruppe Chronisch-entzündliche Darmerkrankungen der ÖGGH.

Infliximab is a monoclonal antibody against tumor necrosis factor alpha (TNF-α), which is approved for the treatment of chronic inflammatory bowel disease (IBD) such as Crohn's disease (CD), fistulating Crohn's disease (FCD), ulcerative colitis (UC), and paediatric ulcerative colitis (PUC) from 6 years onwards. Besides its therapeutic efficacy, this antibody therapy is characterised by its side effects profile, which has been addressed in a seperate consensus statement by the Working Group for chronic inflammatory bowel diseases within the Austrian Society for Gastroenterology and Hepatology. Infliximab is an effective treatment option for the above-mentioned indications; however, use of this agent requires special knowledge to assess the benefit-risk profile for each patient individually.

A decade of infliximab: The Austrian evidence based consensus on the safe use of infliximab in inflammatory bowel disease.

Infliximab (IFX) has tremendously enriched the therapy of inflammatory bowel diseases (IBD) and other immune mediated diseases. Although the efficacy of IFX was undoubtedly proven during the last decade numerous publications have also caused various safety concerns. To summarize the immense information concerning adverse events and safety issues the Austrian Society of Gastroenterology and Hepatology launched this evidence based consensus on the safe use of IFX which covers the following topics: infusion reactions and immunogenicity, skin reactions, opportunistic infections (including tuberculosis), non-opportunistic infections (bacterial and viral), vaccination, neurological complications, hepatotoxicity, congestive heart failure, haematological side effects, intestinal strictures, stenosis and bowel obstruction (SSO), concomitant medication, malignancy and lymphoma, IFX in the elderly and the young, mortality, fertility, pregnancy and breast feeding. To make the vast amount of information practicable for routine application the consensus was finally condensed into a checklist for a safe use of IFX which consists of two parts: issues to be addressed prior to anti-TNF therapy and issues to be addressed during maintenance. Both parts are further divided into obligatory and facultative items.

Endoplasmic reticulum stress and intestinal inflammation.

The intestinal epithelial cell (IEC) is increasingly recognized to play a prominent role as an important intermediary between the commensal microbiota and the intestinal immune system. Moreover, it is now recognized that intestinal inflammation in inflammatory bowel disease (IBD) may arise primarily from IEC dysfunction due to unresolved endoplasmic reticulum (ER) stress as a consequence of genetic disruption of X box binding protein-1 function. In addition to primary (genetic) abnormalities of the unfolded protein response, a variety of secondary (inflammation and environmental) factors are also likely to be important regulators of ER stress. ER stress pathways are also well known to regulate (and be regulated by) autophagy pathways. Therefore, the host's ability to manage ER stress is likely to be a major pathway in the pathogenesis of intestinal inflammation that arises primarily from the IEC. Herein we discuss ER stress in the IEC as both an originator and perpetuator of intestinal inflammation in IBD.

[Adalimumab for the treatment of Crohn's disease - consensus paper of the Working Group "chronic inflammatory bowel diseases" of the Austrian Society for Gastroenterology and Hepatology]. / Adalimumab in der Behandlung des Morbus Crohn - ein Konsensus der Arbeitsgruppe Chronisch Entzündliche Darmerkrankungen der Osterreichischen Gesellschaft für Gastroenterologie und Hepatologie.

The advent of anti-TNF alpha antibodies has clearly improved the outcome of patients with Crohn's disease. With adalimumab, the first fully human, monoclonal anti-TNF alpha antibody, which can be administered subcutaneously by means of a pen, became available in 2007. In Europe adalimumab is approved for the treatment of severe, active Crohn's disease, in patients who have not responded despite a full and adequate course of therapy with a corticosteroid and/or an immunosuppressant; or who are intolerant to or have medical contraindications for such therapies. Adalimumab is clinically efficacious both in patients with Crohn's disease naïve to previous exposure to anti-TNF alpha antibodies and in those previously exposed with a rapid onset of action and a confirmed maintenance performance over 3 years. A reduction in the rate of hospitalisation and an improvement of health-related quality of life are associated with this treatment. The safety profile of adalimumab is comparable to those of other TNF alpha inhibitors. Due to low immunogenicity, allergic reactions are rare. A careful screening of patients before and during treatment with adalimumab is of key importance. The presented therapy guidelines based on existing evidence are aimed to assist in the efficient and safe use of adalimumab in the treatment of Crohn's disease.

Cooperation between GLI and JUN enhances transcription of JUN and selected GLI target genes.

Sustained Hedgehog (HH) signaling is implicated in basal cell carcinoma of the skin and other types of cancer. Here we show that GLI1 and GLI2, the main transcriptional activators of the HH pathway, directly regulate expression of the activator protein 1 (AP-1) family member JUN, a transcription factor controlling keratinocyte proliferation and skin homeostasis. Activation of the JUN promoter by GLI is dependent on a GLI-binding site and the AP-1 sites known to be involved in self-activation of JUN. Transcription of JUN is greatly enhanced in the presence of GLI and requires activated JUN protein. GLI2act is a more potent activator than GLI1 in these experiments and physical interaction with phosphorylated JUN was only detected for GLI2act. The synergistic effect of GLI and JUN extends to the activation of further GLI target genes as shown by shRNA-mediated knockdown of JUN in human keratinocytes. Some of these cooperatively activated genes are involved in cell-cycle progression, which is consistent with a significant reduction of the proliferative potential of GLI in the absence of JUN. These results suggest a novel connection between HH/GLI pathway activity and JUN, which may contribute to the oncogenic activity of HH/GLI signaling in skin.

Gut, inflammation and osteoporosis: basic and clinical concepts.

Chronic inflammatory disorders such as inflammatory bowel diseases (IBD) affect bone metabolism and are frequently associated with the presence of osteoporosis. Bone loss is regulated by various mediators of the immune system such as the pro-inflammatory cytokines tumour necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), IL-6, or interferon-gamma. TNF-alpha, a master cytokine in human IBD, causes bone erosions in experimental models and these effects are exerted by osteoclasts. Other TNF-related cytokines such as receptor activator of nuclear factor kappa B (RANK), its ligand, RANKL, and osteoprotegerin are important mediators in inflammatory processes in the gut and are critically involved in the pathophysiology of bone loss. The awareness and early diagnosis of osteoporosis in states of chronic inflammation, together with applied therapies such as bisphosphonates, may be beneficial in inflammation-associated osteoporosis. Although several mechanisms may contribute to osteoporosis in patients with IBD and coeliac disease, inflammation as an important factor has so far been neglected. As key inflammatory mediators in IBD such as TNF-alpha are involved in the disease process both in gut and bone, we hypothesise that neutralisation of TNF-alpha could prove an efficient strategy in the treatment of inflammation-related osteoporosis in the future.

CD1 expression on antigen-presenting cells.

CD1 proteins present self and microbial glycolipids to CD 1-restricted T cells, or in the case of CD1d, to NKT cells. The CD1 family in humans consists of group I proteins CDla, CDlb, CDlc, and CDle and the group II protein CDld. Rodents express only CDld, but as CD1d is broadly expressed and traffics to all endosomal compartments, this single CD1 family member is thereby able to acquire antigens in many subcellular compartments. A complete understanding of the CD 1 family requires an appreciation of which cells express CD1 and how CD1 contributes to the unique function of each cell type. While group I CD 1 expression is limited to thymocytes and professional APCs, CD1d has a wider tissue distribution and can be found on many nonhematopoietic cells. The expression and regulation of CD1 are presented here with particular emphasis on the function of CD1 in thymocytes, B cells, monocytes and macrophages, dendritic cells (DCs), and intestinal epithelial cells (IECs). Altered expression of CD 1 in cancer, autoimmunity, and infectious disease is well documented, and the implication of CD 1 expression in these diseases is discussed.

Circulating adiponectin reflects severity of liver disease but not insulin sensitivity in liver cirrhosis.

BACKGROUND: The adipocytokine adiponectin has been proposed to play important roles in the regulation of energy homeostasis, insulin sensitivity and shows anti-inflammatory properties. AIM: In this study we investigated the role of circulating adiponectin in different chronic liver diseases, its regulation by systemic anti-tumour necrosis factor (TNF)-alpha treatment and its hepatic metabolism. PATIENTS AND METHODS: Plasma adiponectin levels were determined in 87 patients with liver cirrhosis of different aetiologies, seven patients with alcoholic steatohepatitis undergoing systemic anti-TNF-alpha treatment, in 11 patients with liver cirrhosis receiving transjugular intrahepatic portosystemic shunt implantation and in 21 healthy controls. RESULTS: Adiponectin levels were significantly higher in all subjects with liver cirrhosis of different aetiologies when compared with healthy controls and increased dependent on Child-Pugh classification. In subjects with alcoholic steatohepatitis, systemic anti-TNF-alpha treatment caused a significant decrease in circulating adiponectin. Adiponectin concentrations were similar in portal, hepatic and peripheral veins. No correlation between adiponectin levels and insulin resistance was found in any patient group. CONCLUSIONS: Our data suggest that circulating adiponectin is increased in liver cirrhosis independent of the aetiology of liver disease. We suggest that high adiponectin levels in chronic liver disease might reflect one of the body's anti-inflammatory mechanisms in chronic liver diseases.

Predicting mortality by the Glasgow alcoholic hepatitis score: the long awaited progress?

The new Glasgow alcoholic hepatitis score may represent a substantial improvement in clinical phenotyping and could catalyse the development of new treatments in severe alcoholic hepatitis.