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Various Physiological Functions (various + physiological_function)
Selected AbstractsVacuolar membrane dynamics revealed by GFP-AtVam3 fusion proteinGENES TO CELLS, Issue 7 2002Tomohiro Uemura Background: The plant vacuole is a multifunctional organelle that has various physiological functions. The vacuole dynamically changes its function and shape, dependent on developmental and physiological conditions. Our current understanding of the dynamic processes of vacuolar morphogenesis has suffered from the lack of a marker for observing these processes in living cells. Results: We have developed transgenic Arabidopsis thaliana expressing a vacuolar syntaxin-related molecule (AtVam3/SYP22) fused with green fluorescent protein (GFP). Observations using confocal laser scanning microscopy demonstrated that the plant vacuole contained a dynamic membrane system that underwent a complex architectural remodelling. Three-dimensional reconstitution and time-lapse analysis of GFP-fluorescence images revealed that cylindrical and sheet-like structures were present in the vacuolar lumen and were moving dynamically. The movement, but not the structure itself, was abolished by cytochalasin D, an inhibitor of actin polymerization. This moving structure, which sometimes penetrated through the vacuolar lumen, possessed a dynamic membrane architecture similar to the previously recognized ,transvacuolar strand.' Conclusion: We propose two possible models for the formation of the vacuolar lumenal structure. Membrane structures including protruding tubules and reticular networks have recently been recognized in many other organelles, and may be actively involved in intra- and/or inter-organelle signalling. [source] Translational research to identify clinical applications of hepatocyte growth factorHEPATOLOGY RESEARCH, Issue 8 2009Akio Ido Hepatocyte growth factor (HGF), originally purified from the plasma of patients with fulminant hepatic failure, has been shown to carry out various physiological functions. HGF not only stimulates liver regeneration, but also acts as an antiapoptotic factor in in vivo experimental models. Therefore, HGF is a promising therapeutic agent for the treatment of fatal liver diseases, including fulminant hepatic failure. After performing a number of preclinical tests, our group began an investigator-initiated registered phase I/II clinical trial of patients with fulminant hepatic failure to examine the safety and clinical efficacy of recombinant human HGF. In this article, we will discuss the basic research results as well as the translational research that underpins current attempts to use HGF in various clinical settings. [source] EFFECT OF BUTYRIC ACID SUPPLEMENTATION ON SERUM AND RENAL ANTIOXIDANT ENZYME ACTIVITIES IN STREPTOZOTOCIN-INDUCED DIABETIC RATSJOURNAL OF FOOD BIOCHEMISTRY, Issue 2010A. PUNEETH KUMAR ABSTRACT Reactive oxygen metabolites, which are constant products of normal aerobic cell metabolism, play a key role in worsening the pathophysiological complications of diabetes. The present investigation was aimed at understanding the effect of butyric acid supplementation along with wheatbran and guar gum on serum and renal antioxidant enzyme activities and lipid peroxidation in streptozotocin (STZ)-induced diabetic rats. Activities of superoxide dismutase, catalase, glutathione peroxidase were evaluated in serum and kidney of control and experimental rats. Results clearly showed that the altered activity of the enzymes during diabetes was significantly ameliorated by butyric acid (500 mg/kg body weight/day) supplementation compared with other experimental groups. Further, the increased lipid peroxidation in serum and kidney of diabetic rats was also significantly reduced in butyric acid-supplemented diabetic rats. The study led us to conclude that butyric acid exert antioxidant property, thereby minimizing oxidative stress induced diabetes and its related complications. PRACTICAL APPLICATIONS Butyric acid , a product of dietary fiber fermentation , is a four-carbon fatty acid, which has wide range of application in disease management. This product is involved in various physiological functions of body like cell differentiation, apoptosis, colonic homeostasis, histone acetylation, etc. It is also known to decrease the incidence of bowel cancer and some of its analogues are shown to selectively improve glucose-stimulated insulin release and glucose tolerance in both normal and diabetic rats. This study aims to evaluate the beneficial effects of butyric acid supplementation on oxidative stress-induced diabetic complications in rats. [source] PAR4: A new role in the modulation of visceral nociceptionNEUROGASTROENTEROLOGY & MOTILITY, Issue 11 2009S. Bradesi Abstract,Protease-activated receptors (PARs) are a family of G-protein-coupled receptors with a widespread distribution that are involved in various physiological functions including inflammation and nociception. In a recent study in Neurogastroenterology and Motility, Augé et al. describe for the first time the presence of PAR4 on visceral primary afferent neurons and its role in modulating colonic nociceptive responses, colonic hypersensitivity and primary afferent responses to PAR2 and Transient Receptor Potential Vanilloid-4 (TRPV4). Using the model of visceromotor response (VMR) to colorectal distension (CRD), they show that a PAR4 agonist delivered into the colon lumen decreases basal visceral response to CRD and reduces the exacerbated VMR to CRD induced by treatment with PAR2 or TRPV4 agonists. In isolated sensory neurons, they show that a PAR4 agonist inhibits calcium mobilization induced by PAR2 or TRPV4 agonists. Finally, they describe increased pain behaviour evoked by luminal application of mustard oil in PAR4 deficient mice compared to wild type controls. The newly discovered role of PAR4 in modulating visceral pain adds to our growing understanding of the contribution of colonic proteases and PARs to the mechanisms involved in colonic hypersensitivity and their potential role as therapeutic targets for irritable bowel syndrome. [source] Short-period hypoxia increases mouse embryonic stem cell proliferation through cooperation of arachidonic acid and PI3K/Akt signalling pathwaysCELL PROLIFERATION, Issue 2 2008S. H. Lee Hypoxia plays important roles in some early stages of mammalian embryonic development and in various physiological functions. This study examined the effect of arachidonic acid on short-period hypoxia-induced regulation of G1 phase cell-cycle progression and inter-relationships among possible signalling molecules in mouse embryonic stem cells. Hypoxia increased the level of hypoxia-inducible factor-1, (HIF-1,) expression and H2O2 generation in a time-dependent manner. In addition, hypoxia increased the levels of cell-cycle regulatory proteins (cyclin D1, cyclin E, cyclin-dependent kinase 2 (CDK2) and CDK4). Maximum increases in the level of these proteins and retinoblastoma phosphorylation were observed after 12,24 h of exposure to hypoxic conditions, and then decreased. Alternatively, the level of the CDK inhibitors, p21Cip1 and p27Kip1 were decreased. These results were consistent with the results of [3H]-thymidine incorporation and cell counting. Hypoxia also increased the level of [3H]-arachidonic acid release and inhibition of cPLA2 reduced hypoxia-induced increase in levels of the cell-cycle regulatory proteins and [3H]-thymidine incorporation. The level of cyclooxygenase-2 (COX-2) was also increased by hypoxia and inhibition of COX-2 decreased the levels of cell-cycle regulatory proteins and [3H]-thymidine incorporation. Indeed, the percentage of cells in S phase, levels of cell cycle regulatory proteins, and [3H]-thymidine incorporation were further increased in hypoxic conditions with arachidonic acid treatment compared to normoxic conditions. Hypoxia-induced Akt and mitogen-activated protein kinase (MAPK) phosphorylation was inhibited by vitamin C (antioxidant, 10,3 M). In addition, hypoxia-induced increase of cell-cycle regulatory protein expression and [3H]-thymidine incorporation were attenuated by LY294002 (PI3K inhibitor, 10,6 M), Akt inhibitor (10,6 M), rapamycin (mTOR inhibitor, 10,9 M), PD98059 (p44/42 inhibitor, 10,5 M), and SB203580 (p38 MAPK inhibitor, 10,6 M). Furthermore, hypoxia-induced increase of [3H]-arachidonic acid release was blocked by PD98059 or SB203580, but not by LY294002 or Akt inhibitor. In conclusion, arachidonic acid up-regulates short time-period hypoxia-induced G1 phase cyclins D1 and E, and CDK 2 and 4, in mouse embryonic stem cells through the cooperation of PI3K/Akt/mTOR, MAPK and cPLA2 -mediated signal pathways. [source] | |||||||||||||