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  • American Physiological Society  (8)
  • 1
    Online-Ressource
    Online-Ressource
    American Physiological Society ; 1998
    In:  American Journal of Physiology-Gastrointestinal and Liver Physiology Vol. 275, No. 3 ( 1998-09-01), p. G556-G563
    In: American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 275, No. 3 ( 1998-09-01), p. G556-G563
    Kurzfassung: Endothelin (ET), a vasoconstrictive peptide, is known to have a variety of biological actions. Although ET is released by vascular endothelial cells, other cell populations also have been reported to synthesize and release ET. In this study, we examined whether ET is synthesized by intestinal epithelial cells and whether it affects induction of epithelial cell proliferation by interleukin-2 (IL-2). Subconfluent monolayers of intestinal epithelial cells (IEC-6 and IEC-18) were maintained in serum-free medium before addition of rat IL-2. Both IEC-6 and IEC-18 cells released ET-1 into the medium under unstimulated conditions, as determined by a sandwich ELISA. IL-2 significantly enhanced ET-1 release in a time-dependent manner. ET-3 was not detectable in the culture media of either cell line. Expression of ET-1 and ET-3 mRNA in epithelial cells was assessed by competitive PCR. Both cell lines were shown to express ET-1 mRNA, but no ET-3 mRNA was detected. IL-2 treatment enhanced ET-1 mRNA expression by both IEC-6 and IEC-18 cells. Both cell lines also expressed mRNA for ET A and ET B receptor subtypes. When cell proliferation was assessed, exogenous ET-1 induced a slight proliferative response in both types of cells that was consistent and significant at low ET-1 concentrations; cell growth was inhibited at a higher concentration (10 −7 M). IL-2 produced a significant proliferative response in both cell lines. However, the addition of ET-1 (10 −7 M) to culture media attenuated the IL-2-induced increase in cell proliferation. ET A -receptor antagonists significantly enhanced cellular proliferation, suggesting involvement of the ET A receptor in modulation of IL-2-induced intestinal epithelial cell growth.
    Materialart: Online-Ressource
    ISSN: 0193-1857 , 1522-1547
    Sprache: Englisch
    Verlag: American Physiological Society
    Publikationsdatum: 1998
    ZDB Id: 1477329-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Online-Ressource
    Online-Ressource
    American Physiological Society ; 2006
    In:  American Journal of Physiology-Heart and Circulatory Physiology Vol. 290, No. 2 ( 2006-02), p. H590-H598
    In: American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 290, No. 2 ( 2006-02), p. H590-H598
    Kurzfassung: When selectively overexpressed in mouse heart, TNF-α effects the development of a cardiomyopathy that closely mimics that seen in human failing hearts. It has been suggested that two intracellular signaling pathways, the Akt protein kinase and the NF-κB transcription factor, mediated TNF-α signaling. The present experiments assessed the effects of TNF-α overexpression on these two target proteins in vivo. We measured cardiac Akt kinase phosphorylation and NF-κB activity in mice overexpressing TNF-α (TNF1.6). Both basal and insulin-stimulated Akt phosphorylation were reduced by almost 70% by TNF-α overexpression. By contrast, NF-κB was robustly activated. These effects were absent when TNF-α receptor 1 (TNFR1) was selectively ablated. Cardiomyocyte-specific overexpression of the dominant-negative inhibitory κB protein transgene and subsequent inhibition of NF-κB activity attenuated the effects of TNF-α on Akt phosphorylation. NF-κB inhibition also significantly improved fractional shortening and diminished ventricular hypertrophy and survival without affecting infiltrative inflammation or cytokine expression. Thus, while overexpression of TNF-α effected a marked Akt inhibition and NF-κB activation in mouse hearts, inhibition of NF-κB offered salutary benefits mediated at least in part through activation of Akt.
    Materialart: Online-Ressource
    ISSN: 0363-6135 , 1522-1539
    RVK:
    Sprache: Englisch
    Verlag: American Physiological Society
    Publikationsdatum: 2006
    ZDB Id: 1477308-9
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    In: American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 304, No. 8 ( 2013-04-15), p. G700-G707
    Kurzfassung: Glucagon-like peptide-1 (GLP-1) promotes insulin release; however, the relationship between the GLP-1 signal and chronic pancreatitis is not well understood. Here we focus on chemokine (C-C motif) ligand 2 (CCL2) and its receptor (CCR2) axis, which regulates various immune cells, including macrophages, to clarify the mechanism of GLP-1-mediated insulin secretion in chronic pancreatitis in mice. One and multiple series of repetitive cerulein administrations were used to induce acute and chronic cerulein pancreatitis, respectively. Acute cerulein-administered CCR2-knockout (KO) mice showed suppressed infiltration of CD11b + Gr-1 low macrophages and pancreatic inflammation and significantly upregulated insulin secretion compared with paired wild-type (WT) mice. However, chronic cerulein-administered CCR2-KO mice showed significantly increased infiltration of CD11b + /Gr-1 − and CD11b + /Gr-1 high cells, but not CD11b + /Gr-1 low cells, in pancreas with severe inflammation and significantly decreased insulin secretion compared with their WT counterparts. Furthermore, although serum GLP-1 levels in chronic cerulein-administered WT and CCR2-KO mice were comparably upregulated after cerulein administrations, GLP-1 receptor levels in pancreases of chronic cerulein-administered CCR2-KO mice were significantly lower than in paired WT mice. Nevertheless, a significantly higher hyperglycemia level in chronic cerulein-administered CCR2-KO mice was markedly restored by treatment with a GLP-1 analog to a level comparable to the paired WT mice. Collectively, the CCR2/CCL2 axis-mediated CD11b + -cell migration to the pancreas is critically involved in chronic pancreatitis-mediated hyperglycemia through the modulation of GLP-1 receptor expression and insulin secretion.
    Materialart: Online-Ressource
    ISSN: 0193-1857 , 1522-1547
    Sprache: Englisch
    Verlag: American Physiological Society
    Publikationsdatum: 2013
    ZDB Id: 1477329-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Online-Ressource
    Online-Ressource
    American Physiological Society ; 2003
    In:  American Journal of Physiology-Gastrointestinal and Liver Physiology Vol. 285, No. 1 ( 2003-07), p. G31-G36
    In: American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 285, No. 1 ( 2003-07), p. G31-G36
    Kurzfassung: Bile acids transactivate the EGF receptor (EGFR) in cholangiocytes. However, the mechanisms by which bile acids transactivate the EGFR remain unknown. Our aims were to examine the effects of bile acids on EGFR activation in human cholangiocyte cell lines KMBC and H-69. Bile acids stimulated cell growth and induced EGFR phosphorylation in a ligand-dependent manner. Although cells constitutively expressed several EGFR ligands, only transforming growth factor-α (TGF-α) antisera effectively blocked bile acid-induced EGFR phosphorylation. Consistent with the concept that matrix metalloproteinase (MMP) activity is requisite for TGF-α membrane release and ligand function, bile acid transactivation of EGFR and cell growth was blocked by an MMP inhibitor. In conclusion, bile acids activate EGFR via a TGF-α-dependent mechanism, and this EGFR activation promotes cellular growth.
    Materialart: Online-Ressource
    ISSN: 0193-1857 , 1522-1547
    Sprache: Englisch
    Verlag: American Physiological Society
    Publikationsdatum: 2003
    ZDB Id: 1477329-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Online-Ressource
    Online-Ressource
    American Physiological Society ; 2001
    In:  American Journal of Physiology-Gastrointestinal and Liver Physiology Vol. 280, No. 5 ( 2001-05-01), p. G939-G948
    In: American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 280, No. 5 ( 2001-05-01), p. G939-G948
    Kurzfassung: Although the negative effect of excessive alcohol consumption on later stressful events has long been recognized, pathophysiological mechanisms are incompletely understood. We examined possible roles of oxygen radicals and glutathione content in mesenteric venules of chronically ethanol-fed rats exposed to ischemia-reperfusion. Changes in microvascular hemodynamics, such as red blood cell (RBC) velocity, leukocyte adherence, and albumin extravasation, were monitored in postcapillary venules by intravital fluorescence microscopy. Chronic ethanol feeding significantly exaggerated the magnitude of the decrease in RBC velocity, the increased number of adherent leukocytes, and increased albumin leakage elicited by 10 min of ischemia followed by 30 min of reperfusion. Oxidative stress in the endothelium of venules monitored by dihydrorhodamine 123 (DHR) fluorescence was more severe in rats fed ethanol chronically. Both superoxide dismutase and N-acetyl-l-cysteine, which is known to increase glutathione content, reduced the ischemia-reperfusion-induced decrease in RBC velocity, the number of adherent leukocytes, and the increase in albumin leakage, as well as oxidative activation of DHR. This suggests that the increased reperfusion-induced microvascular disturbances in the mesenteric venules of rats fed ethanol chronically are significantly correlated with excessive production of oxygen-derived free radicals and decreased glutathione synthesis.
    Materialart: Online-Ressource
    ISSN: 0193-1857 , 1522-1547
    Sprache: Englisch
    Verlag: American Physiological Society
    Publikationsdatum: 2001
    ZDB Id: 1477329-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Online-Ressource
    Online-Ressource
    American Physiological Society ; 2003
    In:  American Journal of Physiology-Gastrointestinal and Liver Physiology Vol. 284, No. 5 ( 2003-05-01), p. G734-G738
    In: American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 284, No. 5 ( 2003-05-01), p. G734-G738
    Kurzfassung: Toxic bile acids facilitate Fas and tumor necrosis factor-associated apoptosis-inducing ligand (TRAIL) death-receptor oligomerization and activation. Bile acid modulation of death-receptor signaling is multifactorial and includes trafficking of Fas to the cell surface, enhancing TRAIL-R2/DR5 expression, and suppression of function of cFLIP, an antiapoptotic protein modulating death-receptor function. Because bile acid-associated death receptor-mediated apoptosis is a common mechanism for cholestatic hepatocyte injury, inhibition of death receptors and their cascades may prove useful in attenuating liver injury during cholestasis.
    Materialart: Online-Ressource
    ISSN: 0193-1857 , 1522-1547
    Sprache: Englisch
    Verlag: American Physiological Society
    Publikationsdatum: 2003
    ZDB Id: 1477329-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Online-Ressource
    Online-Ressource
    American Physiological Society ; 2004
    In:  American Journal of Physiology-Gastrointestinal and Liver Physiology Vol. 287, No. 3 ( 2004-09), p. G695-G705
    In: American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 287, No. 3 ( 2004-09), p. G695-G705
    Kurzfassung: Acute ethanol exposure induces oxidative stress and apoptosis in primary rat hepatocytes. Previous data indicate that the mitochondrial permeability transition (MPT) is essential for ethanol-induced apoptosis. However, the mechanism by which ethanol induces the MPT remains unclear. In this study, we investigated the role of Bax, a proapoptotic Bcl-2 family protein, in acute ethanol-induced hepatocyte apoptosis. We found that Bax translocates from the cytosol to mitochondria before mitochondrial cytochrome c release. Bax translocation was oxidative stress dependent. Mitochondrial Bax formed a protein complex with the mitochondrial voltage-dependent anion channel (VDAC). Prevention of Bax-VDAC interactions by a microinjection of anti-VDAC antibody effectively prevented hepatocyte apoptosis by ethanol. In conclusion, these data suggest that Bax translocation from the cytosol to mitochondria leads to the subsequent formation of a Bax-VDAC complex that plays a crucial role in acute ethanol-induced hepatocyte apoptosis.
    Materialart: Online-Ressource
    ISSN: 0193-1857 , 1522-1547
    Sprache: Englisch
    Verlag: American Physiological Society
    Publikationsdatum: 2004
    ZDB Id: 1477329-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Online-Ressource
    Online-Ressource
    American Physiological Society ; 1999
    In:  American Journal of Physiology-Gastrointestinal and Liver Physiology Vol. 277, No. 4 ( 1999-10), p. G763-G772
    In: American Journal of Physiology-Gastrointestinal and Liver Physiology, American Physiological Society, Vol. 277, No. 4 ( 1999-10), p. G763-G772
    Materialart: Online-Ressource
    ISSN: 0193-1857 , 1522-1547
    Sprache: Englisch
    Verlag: American Physiological Society
    Publikationsdatum: 1999
    ZDB Id: 1477329-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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