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Important Mediator (important + mediator)
Selected AbstractsHelicobacter pylori activates protein kinase C delta to control Raf in MAP kinase signalling: Role in AGS epithelial cell scattering and elongationCYTOSKELETON, Issue 10 2009Sabine Brandt Abstract Helicobacter pylori is a major etiological agent in the development of chronic gastritis, duodenal ulcer and gastric carcinoma in humans. Virulent H. pylori strains harbor a type IV secretion system (T4SS) encoded by the cag pathogenicity island. This T4SS injects the CagA protein into gastric epithelial cells leading to actin-cytoskeletal rearrangements followed by cell elongation and scattering. Here we report that PMA (4,-phorbol-12-myristate-13-acetate), a well-known cell-permeable activator of protein kinase C (PKC), induces a remarkably similar cellular phenotype as compared to infection with H. pylori. PKCs comprise a large family of serine/threonine kinases which are important for multiple physiological processes of host cells. We therefore investigated the role of individual PKC members and the signalling pathways involved in phenotypical outcome. Using isoform-specific silencing RNAs and pharmacological inhibitors we found that two isoforms, PKC-, and PKC-,, were essential for both PMA- and H. pylori -induced elongation phenotype. Furthermore, we provide evidence that PKC-, activity is profoundly stimulated during the course of infection using activation-specific antibodies against PKC phosphorylated at threonine residue 505 or serine residue 660. Infection with H. pylori wild-type and mutants showed that at least two bacterial factors activate PKC-, in a time-dependent manner, one of which is CagA. Immunofluorescence microscopy studies further demonstrated that phosphorylated PKC-, is accumulated and recruited to dynamic actin-structures at the cell membrane. Finally, we show that PKC-, specifically targets Raf kinase to stimulate the Erk1/2 kinase pathway, which is also crucial for phenotypical outcome. Thus, PKC-, is another important mediator of H. pylori -induced pathogenesis. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. [source] Synthetic matrix metalloproteinase inhibitor decreases early cardiac neural crest migration in chicken embryosDEVELOPMENTAL DYNAMICS, Issue 4 2002D.H. Cai Abstract During early embryonic development, cardiac neural crest (NC) cells emerge from the forming neural tube, migrate beneath the ectoderm, enter the pharyngeal arches, and subsequently participate in the septation of the heart. Like tumor cells, NC cells penetrate through basement membranes and invade extracellular matrix during their emigration and migration and, therefore, are liable to use similar invasive mechanisms. Matrix metalloproteinases (MMPs) are a family of zinc proteolytic enzymes known to be important in cell migration and invasion of normal and metastatic cells. In an earlier study, we found that the spatial and temporal distribution pattern of MMP-2 positively correlates with cardiac NC migration, suggesting MMP enzymatic activity may be important in mediating cardiac cell NC migration. To test this hypothesis, a synthetic MMP inhibitor, KB8301, was used to block MMP enzymatic activity during in vitro and in vivo cardiac NC cell migration in chick embryos. Injection of KB8301 into the cell-free space adjacent to the neural tube at the level of the second somite before the NC cells emigrated caused major morphologic anomalies in embryos and disrupted cardiac NC morphogenesis. Unilateral injection of KB8301 at lower concentrations, significantly decreased cardiac NC migration on the injected side compared with the noninjected side and compared with that of the injected controls. This decrease correlated with a decrease in MMP activity in the embryos and was not attributable to differences in embryo size or rate of embryonic development after injection. KB8301 also significantly decreased the rate of NC cell motility and distance NC cells migrated from explanted neural tubes and increased cell area and perimeter. These data suggest that MMP enzymatic activity is an important mediator of early cardiac NC migration and that perturbation of endogenous MMP activity may lead to NC-related congenital defects. © 2002 Wiley-Liss, Inc. [source] Thaliporphine protects ischemic and ischemic-reperfused rat hearts via an NO-dependent mechanismDRUG DEVELOPMENT RESEARCH, Issue 3 2001Li-Man Hung Abstract In ischemia or ischemia-reperfusion (I/R), nitric oxide (NO) can potentially exert several beneficial effects. Thaliporphine, a natural alkaloid with Ca2+ channel-activating and Na+/K+ channel-blocking activities, increased NO levels and exerted cardioprotective action in ischemic or I/R rats. The role of NO in the cardioprotective actions of thaliporphine was assessed. The severity of rhythm disturbances and mortality in anesthetized rats with either coronary artery occlusion for 30 min, or 5 min followed by 30-min reperfusion, were monitored and compared in thaliporphine- vs. placebo-treated groups. Thaliporphine treatment significantly increased NO and decreased lactate dehydrogenase (LDH) levels in the blood during the end period of ischemia or I/R. These changes in NO and LDH levels by thaliporphine were associated with a reduction in the incidence and duration of ventricular tachycardia (VT) and ventricular fibrillation (VF) during ischemic or I/R period. The mortality of animals was also completely prevented by 1 × 10,8 moles/kg of thaliporphine. In animals subjected to 4 h of left coronary artery occlusion, 1 × 10,7 moles/kg of thaliporphine dramatic reduced cardiac infarct zone from 46 ± 6% to 7.1 ± 1.9%. Inhibition of NO synthesis with 3.7 × 10,6 moles/kg of N, -nitro-L-arginine methyl ester (L-NAME) abolished the beneficial effects of thaliporphine during 30 min or 4 h myocardial ischemia. However, the antiarrhythmic activity and mortality reduction efficacy of thaliporphine during reperfusion after 5 min of ischemia was only partially antagonized by L-NAME. These results showed that thaliporphine efficiently exerted the cardioprotections either in acute or prolonged coronary artery occlusion or occlusion-reperfusion situations. The fact that thaliporphine induced cardioprotective effects were abrogated by L-NAME indicates that NO is an important mediator for the cardioprotective effects of thaliporphine in acute or prolonged ischemia, whereas antioxidant activities may contribute to the protection of I/R injury. Drug Dev. Res. 52:446,453, 2001. © 2001 Wiley-Liss, Inc. [source] Active immunization with IL-1 displayed on virus-like particles protects from autoimmune arthritisEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2008Gunther Spohn Abstract IL-1 is an important mediator of inflammation and a major cause of tissue damage in rheumatoid arthritis (RA). Therapeutic administration of recombinant IL-1 receptor antagonist (IL-1Ra) is efficacious in reducing clinical symptoms of disease, but suffers from several drawbacks, including the need for frequent administrations of large amounts. Here, we show that immunization of mice with either IL-1, or IL-1, chemically cross-linked to virus-like particles (VLP) of the bacteriophage Q, elicited a rapid and long-lasting autoantibody response. The induced Ab efficiently neutralized the binding of the respective IL-1 molecules to their receptors in vitro and their pro-inflammatory activities in vivo. In the collagen-induced arthritis model, both vaccines strongly protected mice from inflammation and degradation of bone and cartilage. Moreover, immunization with either vaccine showed superior efficacy than daily administrations of high amounts of IL-1Ra. In the T and B cell-independent collagen Ab transfer model, immunization with the IL-1, vaccine strongly protected from arthritis, whereas immunization with the IL-1, vaccine had no effect. Our results suggest that active immunization with IL-1,, and especially IL-1, conjugated to Q, VLP, might become an efficacious and cost-effective new treatment option for RA and other systemic IL-1-dependent inflammatory disorders. [source] Regulation of ,FosB transcriptional activity by Ser27 phosphorylationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2007Paula G. Ulery Abstract The transcription factor, ,FosB, is an important mediator of the long-term plasticity induced in brain by chronic exposure to drugs of abuse, stress, or several other psychoactive stimuli. We have previously demonstrated that the casein kinase 2 (CK2)-mediated phosphorylation of a highly conserved N-terminal serine (Ser27) plays a critical role in regulating ,FosB's unusual stability, while it does not affect that of the full-length FosB protein. In the present study, we analysed whether CK2 and Ser27 phosphorylation also play a role in regulating ,FosB's transcriptional activity. Our findings indicate that CK2 activation increases ,FosB's transactivation potential, while CK2 inhibition decreases it. Further, we show that preventing Ser27 phosphorylation by mutating the site to Ala results in a significant decrease in ,FosB transactivation, without affecting ,FosB's subcellular localization or DNA-binding affinity. In contrast, Ser27 does not seem to play a role in the transactivation potential of full-length FosB. These findings constitute the first evidence of a role for phosphorylation in ,FosB's transcriptional activity. [source] Generalization of positive attitude as a function of subgroup and superordinate group identifications in intergroup contactEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 2 2003Roberto González The role of category salience in mediating the effects of intergroup contact was examined. One theoretical model proposes that some psychological salience of subgroup categories is necessary to facilitate the generalization of attitude change beyond the immediate contact situation. Another argues that a re-categorization of the subgroups into a new superordinate category is more beneficial, whilst a third suggests that de-categorizing the situation entirely is optimal. An alternative view, which combines the first two models, proposes a Dual Identity strategy (simultaneous high superordinate and high subgroup categorization) as an important mediator of the relationship between contact variables and intergroup attitudes. In the study, participants (N,=,114) undertook a cooperative intergroup task under four conditions of category salience: ,subgroup', ,superordinate', ,superordinate and subgroup', and ,no group salience'. Evaluative ratings and symbolic reward allocations both for the groups encountered (contact) and those outside the situation (generalization) provided measures of intergroup bias. Bias within the contact situation was mainly eliminated in all conditions. However, on the more generalized bias measures, only the ,superordinate' and ,superordinate and subgroup' (Dual Identity strategy) conditions maintained this low level; in the other two conditions intergroup bias resurfaced. A combination of the first two models is proposed. Copyright © 2002 John Wiley & Sons, Ltd. [source] Screening of urocanic acid isomers in human basal and squamous cell carcinoma tumors compared with tumor periphery and healthy skinEXPERIMENTAL DERMATOLOGY, Issue 10 2008Juan Manuel Decara Abstract:,Trans -urocanic acid is a major chromophore for ultraviolet (UV) radiation in human epidermis. The UV induces photoisomerization of trans -urocanic acid (tUCA) form to cis -urocanic acid (cUCA) and has been reported as an important mediator in the immunosuppression induced by UV. This immunomodulation has been recognized as an important factor related to skin cancer development. This is the first time that UCA isomers have been measured in epidermis of skin biopsies from patients with squamous cell carcinoma (SCC) and with basal cell carcinoma (BCC) and compared with the tumor periphery and biopsies of healthy photoexposed and non-photoexposed skin as controls. The UCA isomers were separated and quantified by high performance liquid chromatography. Analysis of UCA in healthy skin showed significant increase in total UCA content in non-photoexposed body sites compared with highly exposed skins. In contrast, the percentage of cUCA was higher in photoexposed body sites. Maximal levels of cUCA were found in cheek, forehead and forearm and lower levels in abdomen and thigh. No differences were found in total UCA concentration between the tumor samples and healthy photoexposed skin. However, differences were found in relation between isomers. Higher levels of cUCA were detected in SCC biopsies (44% of total UCA) compared with samples of BCC and that of healthy photoexposed skin (30%). These results suggest that the UV radiation exposure, a main factor in development of SCC can be mediated, apart from direct effect to cells (DNA damage), by immunosuppression pathways mediated by high production of cUCA. [source] Phosphorylation of NF-,B proteins by cyclic GMP-dependent kinaseFEBS JOURNAL, Issue 10 2003A noncanonical pathway to NF-, B activation The transcription factor NF-,B is activated in cellular stress responses. This requires rapid regulation of its function, which is accomplished, in part, by various modes of phosphorylation. Even though diverse DNA binding subunits of NF-,B proteins may transactivate from distinct recognition sequences, the differential regulation of transcription from the large number of NF-,B responsive sites in various gene promoters and enhancers has been incompletely understood. The cyclic GMP-dependent kinase (PKG) is an important mediator of signal transduction that may induce gene expression through cAMP response element binding protein (CREB) and through other, yet undefined, mechanisms. We have previously characterized a signal transduction pathway that leads to activation-induced cell death in T-lymphocytes and involves the activation of PKG. Here we demonstrate that the NF-,B proteins p65, p49 (also called p52), and p50 are specific substrates for this kinase. PKG dose-dependently increases the transactivating activity of p65 from the NF-,B consensus sequence. It also mediates dose-dependently an increase in transcriptional activity by p49 or p50 from a unique CCAAT/enhance binding protein (C/EBP)-associated NF-,B site, but not from the consensus site. Phosphorylation of p65, p50, or p49 does not alter their subcellular distribution. Because the release of cytosolic p65/p50 heterodimers into the nucleus is by itself insufficient to differentiate all the numerous NF-,B promoter sequences, phosphorylation of the DNA-binding subunits reveals a form of differential regulation of NF-,B activity and it implies a novel pathway for PKG-induced gene transcription. These observations may bear on mechanisms of programmed cell death in T-lymphocytes. They may also be relevant to ongoing efforts to induce cancer cell apoptosis through activation of PKG. [source] Calcineurin phosphatase in signal transduction: lessons from fission yeastGENES TO CELLS, Issue 7 2002Reiko Sugiura Calcineurin (protein phosphatase 2B), the only serine/threonine phosphatase under the control of Ca2+/calmodulin, is an important mediator in signal transmission, connecting the Ca2+ -dependent signalling to a wide variety of cellular responses. Furthermore, calcineurin is specifically inhibited by the immunosuppressant drugs cyclosporin A and tacrolimus (FK506), and these drugs have been a powerful tool for identifying many of the roles of calcineurin. Calcineurin is enriched in the neural tissues, and also distributes broadly in other tissues. The structure of the protein is highly conserved from yeast to man. The combined use of powerful genetics and of specific calcineurin inhibitors in fission yeast Schizosaccharomyces pombe (S. pombe) identified new components of the calcineurin pathway, and defined new roles of calcineurin in the regulation of the many cellular processes. Recent data has revealed functional interactions in which calcineurin phosphatase is involved, such as the cross-talk between the Pmk1 MAP kinase signalling, or the PI signalling. Calcineurin also participates in membrane traffic and cytokinesis of fission yeast through its functional connection with members of the small GTPase Rab/Ypt family, and Type II myosin, respectively. These findings highlight the potential of fission yeast genetic studies to elucidate conserved elements of signal transduction cascades. [source] Biliverdin therapy protects rat livers from ischemia and reperfusion injuryHEPATOLOGY, Issue 6 2004Constantino Fondevila Heme oxygenase (HO-1) provides a cellular defense mechanism during oxidative stress and catalyzes the rate-limiting step in heme metabolism that produces biliverdin (BV). The role of BV and its potential use in preventing ischemia/reperfusion injury (IRI) had never been studied. This study was designed to explore putative cytoprotective functions of BV during hepatic IRI in rat liver models of ex vivo perfusion and orthotopic liver transplantation (OLT) after prolonged periods of cold ischemia. In an ex vivo hepatic IRI model, adjunctive BV improved portal venous blood flow, increased bile production, and decreased hepatocellular damage. These findings were correlated with amelioration of histological features of IRI, as assessed by Suzuki's criteria. Following cold ischemia and syngeneic OLT, BV therapy extended animal survival from 50% in untreated controls to 90% to 100%. This effect correlated with improved liver function and preserved hepatic architecture. Additionally, BV adjuvant after OLT decreased endothelial expression of cellular adhesion molecules (P-selectin and intracellular adhesion molecule 1), and decreased the extent of infiltration by neutrophils and inflammatory macrophages. BV also inhibited expression of inducible nitric oxide synthase and proinflammatory cytokines (interleukin 1,, tumor necrosis factor ,, and interleukin 6) in OLTs. Finally, BV therapy promoted an increased expression of antiapoptotic molecules independently of HO-1 expression, consistent with BV being an important mediator through which HO-1 prevents cell death. In conclusion, this study documents and dissects potent cytoprotective effects of BV in well-established rat models of hepatic IRI. Our results provide the rationale for a novel therapeutic approach using BV to maximize the function and thus the availability of donor organs. (HEPATOLOGY 2004;40:1333,1341.) [source] A novel mechanism for mitogenic signaling via pro,transforming growth factor , within hepatocyte nucleiHEPATOLOGY, Issue 6 2002Bettina Grasl-Kraupp Transforming growth factor (TGF) ,, an important mediator of growth stimulation, is known to act via epidermal growth factor receptor (EGF-R) binding in the cell membrane. Here we show by immunohistology, 2-dimensional immunoblotting, and mass spectrometry of nuclear fractions that the pro-protein of wild-type TGF-, occurs in hepatocyte nuclei of human, rat, and mouse liver. Several findings show a close association between nuclear pro-TGF-, and DNA synthesis. (1) The number of pro-TGF-,+ nuclei was low in resting liver and increased dramatically after partial hepatectomy and after application of hepatotoxic chemicals or the primary mitogen cyproterone acetate (CPA); in any case, S phase occurred almost exclusively in pro-TGF-,+ nuclei. The same was found in human cirrhotic liver. (2) In primary culture, 7% of hepatocytes synthesized pro-TGF-,, which then translocated to the nucleus; 70% of these nuclei subsequently entered DNA replication, whereas only 2% of pro-TGF-,, hepatocytes were in S phase. (3) The frequency of hepatocytes coexpressing pro-TGF-, and DNA synthesis was increased by the hepatomitogens CPA or prostaglandin E2 and was decreased by the growth inhibitor TGF-,1. (4) Treatment with mature TGF-, increased DNA synthesis exclusively in pro-TGF-,, hepatocytes, which was abrogated by the EGF-R tyrosine kinase inhibitor tyrphostin A25. In conclusion, TGF-, gene products may exert mitogenic effects in hepatocytes via 2 different signaling mechanisms: (1) the "classic" pathway of mature TGF-, via EGF-R in the membrane and (2) a novel pathway involving the presence of pro-TGF-, in the nucleus. [source] Increase of granzyme B-positive cells in ascitic fluid of patients with spontaneous bacterial peritonitisHEPATOLOGY RESEARCH, Issue 4 2008Alessandro Perrella Spontaneous bacterial peritonitis (SBP) occurs as a direct consequence of bacteria entering ascitic fluid (AF) from the intestinal lumen trough in several ways, including the hematogenous and mesenteric lymph nodes route. There are few studies on the cytokine profile of ascitic-derived mononuclear cells of patients with SBP, particularly on granzyme B (GZB). The aim of the present study was to verify whether patients with SBP have GZB-positive cells, whether they are increased in patients with aseptic ascites, and their trend after antibiotic treatment. We enrolled 36 consecutive patients (24 males and 12 females) with SBP on histologically-proven hepatitis C virus cirrhosis (group A) and 20 patients (11 males and nine females with ascites, but without evidences of SBP (group B). The diagnosis of SBP was made according to the following criteria: positive colture in AF or blood (at least two cultures) and neutrophils in AF (>250 mL polymorphonuclear leukocytes). For these patients we used ELISpot to assay GZB production on purified mononuclear cells in ascitesand peripheral blood, coupled with tumor necrosis factor-, tested using ELISA. A non-parametric statistical analysis was used to assess significant differences and correlations. We found positive culture in all of the patients with SBP (80% Escherichia coli; 20% Enterococcus faecium). Furthermore, the patients in group A had a higher number of GZB spot-forming colonies than the patients in group B (P < 0.001). GZB-positive cells were lower in the peripheral blood than those found in the AF of patients with SBP, while no differences were found between blood and AF in group B. Furthermore, after antibiotic treatment, GZB was reduced in the patients with SBP (P < 0.05). In conclusion, GZB may be an important mediator of the immune response towards bacteria in AF and could be used as a diagnostic tool. [source] Transforming growth factor-,2 modulates synaptic efficacy and plasticity and induces phosphorylation of CREB in hippocampal neuronsHIPPOCAMPUS, Issue 1 2007Teruyuki Fukushima Abstract Transforming growth factor-,s (TGF-,s) are widely expressed and play roles as multifunctional growth factors and regulators of key events in development, disease, and repair. However, it is not known whether TGF-,s affect the plasticity of hippocampal neurons. As a first step to address this issue, we examined whether TGF-,2 modulated the electrophysiological and biochemical properties of cultured hippocampal neurons. We found that prolonged 24 h treatment with TGF-,2 induced facilitation of evoked postsynaptic currents (ePSCs). This facilitation was associated with a decrease in short-term synaptic depression of ePSCs and increases in both the amplitude and frequency of spontaneous miniature postsynaptic currents (mPSCs). The long-term changes of ePSCs and mPSCs may be associated with cAMP response element-binding protein (CREB), which has been previously implicated in long-term potentiation. Immunofluorescence techniques and Western blot analysis both revealed that TGF-,2 enhanced the phosphorylation of CREB. Together, these results suggest that TGF-,2 may play a role in the cascade of events underlying long-term synaptic facilitation in hippocampus, and that CREB may be an important mediator of these effects. © 2006 Wiley-Liss, Inc. [source] Erythropoietin/erythropoietin receptor system is involved in angiogenesis in human neuroblastomaHISTOPATHOLOGY, Issue 5 2007D Ribatti Aims:, Previous studies have shown that increased vascularity is associated with tumour progression in human neuroblastoma (NB). The involvement of erythropoietin (Epo) in tumour angiogenesis has also been reported. The aim of this study was to correlate microvascular density and Epo/Epo-receptor (EpoR) expression in endothelial and tumour cells to the clinical stage of NB. Methods and results:, Specimens of NB obtained from 20 patients were investigated immunohistochemically by using anti-CD31, anti-Epo and anti-EpoR antibodies. The extent of angiogenesis was found to be up-regulated in advanced disease. In keeping with this observation, Epo/EpoR expression in tumour and endothelial cells, respectively, was also highly correlated with the extent of angiogenesis and higher clinical stage. Conclusions:, The correlation of Epo/EpoR expression with angiogenesis and tumour progression suggests the presence of a loop in the Epo,EpoR system. Epo is secreted by tumour cells and affects vascular endothelial cells via its receptor, promoting tumour angiogenesis in a paracrine manner. Data suggest that Epo represents an important mediator in NB angiogenesis. Understanding the mechanisms of NB angiogenesis provides the basis for a rational approach to the development of antiangiogenic therapy in patients affected by NB. [source] Indoleamine 2,3-dioxygenase in T-cell tolerance and tumoral immune escapeIMMUNOLOGICAL REVIEWS, Issue 1 2008Jessica B. Katz Summary: Indoleamine 2, 3-dioxygenase (IDO) degrades the essential amino acid tryptophan in mammals, catalyzing the initial and rate-limiting step in the de novo biosynthesis nicotinamide adenine dinucleotide (NAD). Broad evidence implicates IDO and the tryptophan catabolic pathway in generation of immune tolerance to foreign antigens in tissue microenvironments. In particular, recent findings have established that IDO is overexpressed in both tumor cells and antigen-presenting cells in tumor-draining lymph nodes, where it promotes the establishment of peripheral immune tolerance to tumor antigens. In the normal physiologic state, IDO is important in creating an environment that limits damage to tissues due to an overactive immune system. However, by fostering immune suppression, IDO can facilitate the survival and growth of tumor cells expressing unique antigens that would be recognized normally as foreign. In preclinical studies, small-molecule inhibitors of IDO can reverse this mechanism of immunosuppression, complementing classical cytotoxic cancer chemotherapeutic agents' ability to trigger regression of treatment-resistant tumors. These results have encouraged the clinical translation of IDO inhibitors, the first of which entered phase I clinical trials in the fall of 2007. In this article, we survey the work defining IDO as an important mediator of peripheral tolerance, review evidence of IDO dysregulation in cancer cells, and provide an overview of the development of IDO inhibitors as a new immunoregulatory treatment modality for clinical trials. [source] Serum osteoprotegerin is increased in Crohn's disease: A population-based case control studyINFLAMMATORY BOWEL DISEASES, Issue 4 2005Charles N Bernstein MD Abstract Background: There is a potential interface between osteoporosis and the chronic inflammation of inflammatory bowel disease (IBD), and the osteoprotegerin (OPG)/receptor for activated nuclear factor-,B (RANK)/RANK ligand (RANKL) signaling pathway may be an important mediator, although data are limited. Methods: We conducted a population-based case-control seroassay study to look for alterations in serum OPG and soluble RANKL (sRANKL). The study population included IBD patients who were 18 to 50 years old with Crohn's disease (CD; n = 287) or ulcerative colitis (UC; n = 166), age-matched healthy controls (n = 368), and nonaffected siblings of IBD patients (n = 146). Serum OPG and sRANKL were measured by enzyme-linked immunoassay. Sex-specific reference ranges were derived from the healthy controls. Results: Analysis of variance (ANOVA) confirmed significant group differences in women for mean serum OPG (P = 0.018). CD women had higher values of OPG than UC women (P = 0.028) or healthy controls (P = 0.045), whereas the other groups were similar. OPG levels were above the reference range in 13/173 (8%) of CD women, exceeding the expected proportion (P = 0.032). In contrast, no differences in OPG were seen in men between controls, CD, or UC. Estrogen use in women (P = 0.000002) and corticosteroid use in men (P = 0.026) were associated with higher OPG levels. In multivariate analysis, CD diagnosis (P = 0.031) and estrogen use (P = 0.000002) were independently associated with higher OPG levels. No group differences were seen in mean serum sRANKL measurements. Conclusions: An OPG:sRANKL imbalance with OPG exceeding sRANKL should inhibit osteoclastogenesis and promote bone formation. CD is associated with increased fracture risk, and possibly, the paradoxically higher OPG is a counterregulatory response to factors such as inflammatory cytokines, promoting high bone turnover. Alternatively, elevated OPG in CD may reflect T-cell activation. [source] Growth factor attenuation of IFN,-mediated hepatocyte apoptosis requires p21waf,1INTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 4 2006Christian T. McCullough Summary Interferon gamma (IFN,) is an important mediator of inflammatory liver damage as part of a complex cytokine network. In vitro, IFN, induces hepatocyte apoptosis. We hypothesized that the hepatocyte response to IFN signalling is context-dependent, and that specific growth factors, via phosphatidylinositol 3 kinase (PI(3)K) and protein kinase B/Akt signalling pathways, confer a cytoprotective effect. We established an in vitro model of IFN,-mediated primary hepatocyte injury. We show that epidermal growth factor (EGF) and hepatocyte growth factor (HGF) attenuate the IFN,-induced hepatocyte apoptosis. IRF-1, but not p53, is required for IFN,-mediated apoptosis. The loss of p21waf,1 not only sensitizes the hepatocyte to IFN,-mediated injury but is required for survival factor mediated cytoprotection. We show that the PI(3)K inhibitor, LY294002, partially inhibits the apoptotic response of the hepatocyte to IFN,. In summary, we present evidence that a component of pro-apoptotic IFN, signalling in the primary hepatocyte occurs via the PI(3)K pathway. We show that the hepatocyte response to IFN, is modulated by external survival factors and that this survival signalling requires p21waf,1. [source] Cytokine Stimulation Promotes Increased Glucose Uptake Via Translocation at the Plasma Membrane of GLUT1 in HEK293 CellsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2010Angara Zambrano PhD Abstract Interleukin-3 (IL-3) and granulocyte/macrophage colony-stimulating factor (GM-CSF) are two of the best-characterized cell survival factors in hematopoietic cells; these factors induce an increase in Akt activity in multiple cell lines, a process thought to be involved in cellular survival. It is known that growth factors require sustained glucose metabolism to promote cell survival. It has been determined that IL-3 and GM-CSF signal for increased glucose uptake in hematopoietic cells. Interestingly, receptors for IL-3 and GM-CSF are present in several non-hematopoietic cell types but their roles in these cells have been poorly described. In this study, we demonstrated the expression of IL-3 and GM-CSF receptors in HEK293 cells and analyzed their effect on glucose uptake. In these cells, both IL-3 and GM-CSF, increased glucose uptake. The results indicated that this increase involves the subcellular redistribution of GLUT1, affecting glucose transporter levels at the cell surface in HEK293 cells. Also the data directly demonstrates that the PI 3-kinase/Akt pathway is an important mediator of this process. Altogether these results show a role for non-insulin growth factors in the regulation of GLUT1 trafficking that has not yet been directly determined in non-hematopoietic cells. J. Cell. Biochem. 110: 1471,1480, 2010. © 2010 Wiley-Liss, Inc. [source] The Behavioral Foundations of Trade Secrets: Tangibility, Authorship, and LegalityJOURNAL OF EMPIRICAL LEGAL STUDIES, Issue 2 2006Yuval Feldman This article examines whether the nature of information protected by trade secret law affects departing employees' normative judgments of obedience to trade secret law. This examination assesses two main dimensions: tangibility (whether the employee downloaded the confidential information) and authorship (whether the employee developed the confidential information by himself or herself). The data was collected from a nonrandom multi-sourced sample of 260 high-tech employees in Silicon Valley. Tangibility affected almost all the factors that were measured (such as the perceived consensus and participants' own intention to share information), while authorship affected only participants' moral perceptions. Further analysis revealed that the expected social approval of a new employer was the most important mediator of the effect of tangibility on the intention to share trade secrets. [source] Methamphetamine-induced neurotoxicity and microglial activation are not mediated by fractalkine receptor signalingJOURNAL OF NEUROCHEMISTRY, Issue 2 2008David M. Thomas Abstract Methamphetamine (METH) damages dopamine (DA) nerve endings by a process that has been linked to microglial activation but the signaling pathways that mediate this response have not yet been delineated. Cardona et al. [Nat. Neurosci. 9 (2006), 917] recently identified the microglial-specific fractalkine receptor (CX3CR1) as an important mediator of MPTP-induced neurodegeneration of DA neurons. Because the CNS damage caused by METH and MPTP is highly selective for the DA neuronal system in mouse models of neurotoxicity, we hypothesized that the CX3CR1 plays a role in METH-induced neurotoxicity and microglial activation. Mice in which the CX3CR1 gene has been deleted and replaced with a cDNA encoding enhanced green fluorescent protein (eGFP) were treated with METH and examined for striatal neurotoxicity. METH depleted DA, caused microglial activation, and increased body temperature in CX3CR1 knockout mice to the same extent and over the same time course seen in wild-type controls. The effects of METH in CX3CR1 knockout mice were not gender-dependent and did not extend beyond the striatum. Striatal microglia expressing eGFP constitutively show morphological changes after METH that are characteristic of activation. This response was restricted to the striatum and contrasted sharply with unresponsive eGFP-microglia in surrounding brain areas that are not damaged by METH. We conclude from these studies that CX3CR1 signaling does not modulate METH neurotoxicity or microglial activation. Furthermore, it appears that striatal-resident microglia respond to METH with an activation cascade and then return to a surveying state without undergoing apoptosis or migration. [source] Interleukin-1,: a bridge between inflammation and excitotoxicity?JOURNAL OF NEUROCHEMISTRY, Issue 1 2008Birgit Fogal Abstract Interleukin-1 (IL-1) is a proinflammatory cytokine released by many cell types that acts in both an autocrine and/or paracrine fashion. While IL-1 is best described as an important mediator of the peripheral immune response during infection and inflammation, increasing evidence implicates IL-1 signaling in the pathogenesis of several neurological disorders. The biochemical pathway(s) by which this cytokine contributes to brain injury remain(s) largely unidentified. Herein, we review the evidence that demonstrates the contribution of IL-1, to the pathogenesis of both acute and chronic neurological disorders. Further, we highlight data that leads us to propose IL-1, as the missing mechanistic link between a potential beneficial inflammatory response and detrimental glutamate excitotoxicity. [source] Nitric oxide regulates cell survival in purified cultures of avian retinal neurons: involvement of multiple transduction pathwaysJOURNAL OF NEUROCHEMISTRY, Issue 2 2007T. A. Mejía-García Abstract Nitric oxide (NO) is an important signaling molecule in the CNS, regulating neuronal survival, proliferation and differentiation. Here, we explored the mechanism by which NO, produced from the NO donor S -nitroso-acetyl- d - l -penicillamine (SNAP), exerts its neuroprotective effect in purified cultures of chick retinal neurons. Cultures prepared from 8-day-old chick embryo retinas and incubated for 24 h (1 day in culture, C1) were treated or not with SNAP, incubated for a further 72 h (up to 4 days in culture, C4), fixed, and the number of cells estimated, or processed for cell death estimation, by measuring the reduction of the metabolic dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Experimental cultures were run in parallel but were re-fed with fresh medium in the absence or presence of SNAP at culture day 3 (C3), incubated for a further 24 h up to C4, then fixed or processed for the MTT assay. Previous studies showed that the re-feeding procedure promotes extensive cell death. SNAP prevented this death in a concentration- and time-dependent manner through the activation of soluble guanylate cyclase; this protection was significantly reversed by the enzyme inhibitors 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ) or LY83583, and mimicked by 8-bromo cyclic guanosine 5,-phosphate (8Br-cGMP) (GMP) or 3-(5,-hydroxymethyl-2,-furyl)-1-benzyl indazole (YC-1), guanylate cyclase activators. The effect was blocked by the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). The effect of NO was also suppressed by LY294002, Wortmannin, PD98059, KN93 or H89, indicating the involvement, respectively, of phosphatidylinositol-3 kinase, extracellular-regulated kinases, calmodulin-dependent kinases and protein kinase A signaling pathways. NO also induced a significant increase of neurite outgrowth, indicative of neuronal differentiation, and blocked cell death induced by hydrogen peroxide. Cyclosporin A, an inhibitor of the mitochondrial permeability transition pore considered an important mediator of apoptosis and necrosis, as well as boc-aspartyl (OMe) fluoromethylketone (BAF), a caspase inhibitor, also blocked cell death induced by re-feeding the cultures. These findings demonstrate that NO inhibits apoptosis of retinal neurons in a cGMP/protein kinase G (PKG)-dependent way, and strengthens the notion that NO plays an important role during CNS development. [source] The role of thrombin and thrombin receptors in ischemic, hemorrhagic and traumatic brain injury: deleterious or protective?JOURNAL OF NEUROCHEMISTRY, Issue 1 2003Guohua Xi Abstract In the last two decades it has become apparent that thrombin has many extravascular effects that are mediated by a family of protease-activated receptors (PARs). PAR-1, -3 and -4 are activated via cleavage by thrombin. The importance of extravascular thrombin in modulating ischemic, hemorrhagic and traumatic injury in brain has recently become clear. Thus, in vitro, thrombin at low concentration protects neurons and astrocytes from cell death caused by a number of different insults. In vivo, pretreating the brain with a low dose of thrombin (thrombin preconditioning), attenuates the brain injury induced by a large dose of thrombin, an intracerebral hemorrhage or by focal cerebral ischemia. Thrombin may also be an important mediator of ischemic preconditioning. In contrast, high doses of thrombin kill neurons and astrocytes in vitro and cause disruption of the blood,brain barrier, brain edema and seizures in vivo. This review examines the role of thrombin in brain injury and the molecular mechanisms and signaling cascades involved. [source] Expression of interleukin-1 receptors and their role in interleukin-1 actions in murine microglial cellsJOURNAL OF NEUROCHEMISTRY, Issue 4 2002Emmanuel Pinteaux Abstract Interleukin (IL)-1 is an important mediator of acute brain injury and inflammation, and has been implicated in chronic neurodegeneration. The main source of IL-1 in the CNS is microglial cells, which have also been suggested as targets for its action. However, no data exist demonstrating expression of IL-1 receptors [IL-1 type-I receptor (IL-1RI), IL-1 type-II receptor (IL-1RII) and IL-1 receptor accessory protein (IL-1RAcP)] on microglia. In the present study we investigated whether microglia express IL-1 receptors and whether they present target or modulatory properties for IL-1 actions. RT,PCR analysis demonstrated lower expression of IL-1RI and higher expression of IL-1RII mRNAs in mouse microglial cultures compared with mixed glial or pure astrocyte cultures. Bacterial lipopolysaccharide (LPS) caused increased expression of IL-1RI, IL-1RII and IL-1RAcP mRNAs, induced the release of IL-1,, IL-6 and prostaglandin-E2 (PGE2), and activated nuclear factor ,B (NF-,B) and the mitogen-activated protein kinases (MAPKs) p38, and extracellular signal-regulated protein kinase (ERK1/2), but not c-Jun N-terminal kinase (JNK) in microglial cultures. In comparison, IL-1, induced the release of PGE2, IL-6 and activated NF-,B, p38, JNK and ERK1/2 in mixed glial cultures, but failed to induce any of these responses in microglial cell cultures. IL-1, also failed to affect LPS-primed microglial cells. Interestingly, a neutralizing antibody to IL-1RII significantly increased the concentration of IL-1, in the medium of LPS-treated microglia and exacerbated the IL-1,-induced IL-6 release in mixed glia, providing the first evidence that microglial IL-1RII regulates IL-1, actions by binding excess levels of this cytokine during brain inflammation. [source] Sphingolipids in rat model of transient focal cerebral ischemia: implication for stroke injuryJOURNAL OF NEUROCHEMISTRY, Issue 2002M. Khan Lipids are essential for signal transduction in response to trauma leading to neurodegeneration. Ceramide is an important mediator of apoptosis and cell proliferation. We studied the involvement of ceramide/sphingomyelin pathway in rat brain (stroke model) after 45 min ischemia followed by 24-h reperfusion. Ischemia was performed through occlusion of right middle cerebral artery (MCA). The level of ceramide was found increased (70,100% in ischemic side of brain v/s contralateral side of brain). Sphingomyelin levels were also decreased by 20,25% in ischemic brain v/s contralateral side of brain. Increase in ceramide and decrease in sphingomyelin were in good agreement with observed apoptotic cell loss (TUNEL assay) and decrease in the level of cardiolipin (a mitochondrian specific phospholipids) in affected ischemic brain. N-acetyl cysteine (NAC), a therapeutic agent recognized as potent antioxidant provided protective effect. Pretreatment with NAC before ischemia reduced the infarct volume size, suppressed apoptosis, restored cardiolipin level and decreased the levels of free fatty acids. However, NAC did not normalize the ceramide level. These interesting observations raise a question about the role of ceramide and its relationship with apoptosis and oxidative stress in rat brain ischemia. Acknowledgements:, Supported by NIH grants NS-40144, NS-40810, NS-22576, NS-34741 and NS-37766. [source] Thrombin attenuation is neuroprotective in the injured rat optic nerveJOURNAL OF NEUROCHEMISTRY, Issue 3 2001Igor Friedmann The functional loss that often follows injury of the mammalian CNS has been attributed not only to the immediate neural loss, but also to secondary neuronal degeneration caused by toxic biochemical mediators in the environment of the injured nerve. We report here that a high thrombin content, produced as a result of injury-induced activation of prothrombin, appears to be an important mediator of secondary damage. Measurement of post-traumatic neuronal survival in vivo revealed that post-traumatic local application of the thrombin inhibitor N -,-(2-naphthylsulphonylglycyl)-4-(d,l)-amidinophenylalanine piperidide acetate in the rat optic nerve subjected to mild partial crush injury left twice as many retinal ganglion cells with functioning axons as in controls. Thus, by readjusting thrombin activity, thereby possibly obtaining a moderate post-traumatic increase and thus gaining the benefit of thrombin without its toxic effects, it may be possible to create an environment that is more favourable towards post-traumatic survival. [source] Leptin Uptake by Serotonergic Neurones of the Dorsal RapheJOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2002M. C. Fernández-Galaz Abstract The effects of leptin on food intake, metabolism, sleep patterns and reproduction may be mediated, in part, by the midbrain serotonergic systems. Here, we report on the distribution of neurones that accumulate leptin in the raphe nuclei of male and female rats after intracerebroventricular administration of mouse recombinant leptin labelled with digoxigenin. Direct leptin-targeted cells were present in the periventricular grey, pontine and raphe nuclei. Confocal microscopy revealed that raphe neurones which accumulated leptin were predominantly serotonergic. The temporal pattern of leptin accumulation by raphe neurones showed a marked gender difference: 6 h after leptin administration, all male and female rats showed massive leptin binding in the dorsal raphe, while 30 min after leptin treatment, only 10% of male rats exhibited leptin-labelled cells in contrast to 50% of females. The present observations reveal that leptin can be selectively accumulated by serotonergic neurones in the raphe nuclei and that this mechanism is gender specific. These findings support the idea that the midbrain serotonergic system is an important mediator of the effects of leptin on brain function and may provide an explanation for gender differences in metabolism regulation and its coordination with higher functions of the brain. [source] The mediating effect of burnout on the relationship between structural empowerment and organizational citizenship behavioursJOURNAL OF NURSING MANAGEMENT, Issue 3 2010STEPHANIE GILBERT MSc gilbert s., laschinger h.k.s. &leiter m (2010) Journal of Nursing Management18, 339,348 The mediating effect of burnout on the relationship between structural empowerment and organizational citizenship behaviours Aim, We used Kanter's (1977) structural empowerment theory to examine the influence of structural empowerment and emotional exhaustion on healthcare professionals' use of organizational citizenship behaviours directed at the organization (OCBO) and peers (OCBI). Background, Organizational citizenship behaviours (OCB) are discretionary behaviours that are not rewarded directly by the organization but have been linked to positive outcomes, such as increased job satisfaction and lower turnover intentions. Promoting OCB can help employees and organizations flourish despite current challenges in the healthcare system. Structural empowerment may influence the frequency and type of OCB by reducing burnout. Method, We conducted multiple mediated regression analyses to test two hypothesized models about relationships between empowerment, emotional exhaustion and two types of OCB (OCBI and OCBO) in a sample of 897 healthcare professionals in five Canadian hospitals. Results, Emotional exhaustion was found to be a significant mediator of the relationship between empowerment and OCBO. The predicted mediation of the empowerment/OCBI relationship by emotional exhaustion was not supported. Conclusions, Exhaustion was an important mediator of empowering working conditions and OCBO, but was not significantly related to OCBI. Empowerment was significantly related to both OCBO and OCBI. Implications for nursing management, Promoting empowerment among healthcare workers may decrease burnout and promote OCB. Specific managerial strategies are discussed in the present study. [source] Melatonin suppresses tumor angiogenesis by inhibiting HIF-1, stabilization under hypoxiaJOURNAL OF PINEAL RESEARCH, Issue 2 2010Shi-Young Park Abstract:, Angiogenesis is an important mediator of tumor progression. As tumors expand, diffusion distances from the existing vascular supply increases, resulting in hypoxia in the cancer cells. Sustained expansion of a tumor mass requires new blood vessel formation to provide rapidly proliferating tumor cells with an adequate supply of oxygen and nutrients. The key regulator of hypoxia-induced angiogenesis is the transcription factor known as hypoxia-inducible factor (HIF)-1. HIF-1, is stabilized by hypoxia-induced reactive oxygen species (ROS) and enhances the expression of several types of hypoxic genes, including that of the angiogenic activator known as vascular endothelial cell growth factor (VEGF). In this study, we found that melatonin, a small lipophilic molecule secreted primarily by the pineal gland, destabilizes hypoxia-induced HIF-1, protein levels in the HCT116 human colon cancer cell line. This destabilization of HIF-1, resulted from the antioxidant activity of melatonin against ROS induced by hypoxia. Moreover, under hypoxia, melatonin suppressed HIF-1 transcriptional activity, leading to a decrease in VEGF expression. Melatonin also blocked in vitro tube formation and invasion and migration of human umbilical vein endothelial cells induced by hypoxia-stimulated conditioned media of HCT116 cells. These findings suggest that melatonin could play a pivotal role in tumor suppression via inhibition of HIF-1-mediated angiogenesis. [source] Melatonin in the duodenal lumen is a potent stimulant of mucosal bicarbonate secretionJOURNAL OF PINEAL RESEARCH, Issue 4 2003Markus Sjöblom Abstract: Melatonin, originating from intestinal enterochromaffin cells, mediates vagal and sympathetic neural stimulation of the HCO secretion by the duodenal mucosa. This alkaline secretion is considered the first line of mucosal defense against hydrochloric acid discharged from the stomach. We have studied whether luminally applied melatonin stimulates the protective secretion and whether a melatonin pathway is involved in acid-induced stimulation of the secretion. Rats were anaesthetized (Inactin®) and a 12-mm segment of proximal duodenum with an intact blood supply was cannulated in situ. Mucosal HCO secretion (pH-stat) and the mean arterial blood pressure were continuously recorded. Luminal melatonin at a concentration of 1.0 ,m increased (P < 0.05) the secretion from 7.20 ± 1.35 to 13.20 ± 1.51 ,Eq/cm/hr. The MT2 selective antagonist luzindole (600 nmol/kg, i.v.) had no effect on basal HCO secretion, but inhibited (P < 0.05) secretion stimulated by luminal melatonin. Hexamethonium (10 mg/kg i.v. followed by continuous i.v. infusion at a rate of 10 mg/kg/hr), abolishes neurally mediated rises in secretion and also inhibited (P < 0.05) the stimulation by luminal melatonin. Exposure of the lumen to acid containing perfusate (pH 2.0) for 5 min increased (P < 0.05) the HCO secretion from 5.85 ± 0.82 to 12.35 ± 1.51 ,Eq/cm/hr, and luzindole significantly inhibited (P < 0.05) this rise in secretion. The study thus demonstrates that luminal melatonin is a potent stimulant of duodenal HCO secretion and, furthermore, strongly suggests melatonin as an important mediator of acid-induced secretion. [source] | ||||||||||||||||||||||||||||||||||||||||