Expression and Roles of Individual HIF Prolyl 4-Hydroxylase Isoenzymes in the Regulation of the Hypoxia Response Pathway along the Murine Gastrointestinal Epithelium

The HIF prolyl 4-hydroxylases (HIF-P4H) control hypoxia-inducible factor (HIF), a powerful mechanism regulating cellular adaptation to decreased oxygenation. The gastrointestinal epithelium subsists in “physiological hypoxia” and should therefore have an especially well-designed control over this adaptation. Thus, we assessed the absolute mRNA expression levels of the HIF pathway components, Hif1a, HIF2a, Hif-p4h-1, 2 and 3 and factor inhibiting HIF (Fih1) in murine jejunum, caecum and colon epithelium using droplet digital PCR. We found a higher expression of all these genes towards the distal end of the gastrointestinal tract. We detected mRNA for Hif-p4h-1, 2 and 3 in all parts of the gastrointestinal tract. Hif-p4h-2 had significantly higher expression levels compared to Hif-p4h-1 and 3 in colon and caecum epithelium. To test the roles each HIF-P4H isoform plays in the gut epithelium, we measured the gene expression of classical HIF target genes in Hif-p4h-1^−/−, Hif-p4h-2 hypomorph and Hif-p4h-3^−/− mice. Only Hif-p4h-2 hypomorphism led to an upregulation of HIF target genes, confirming a predominant role of HIF-P4H-2. However, the abundance of Hif-p4h-1 and 3 expression in the gastrointestinal epithelium implies that these isoforms may have specific functions as well. Thus, the development of selective inhibitors might be useful for diverging therapeutic needs.     

Effect of ground rubber powder and devulcanizates on the properties of natural rubber compounds

Ground rubber powder (GRP) and devulcanized rubber (Dev.R) waste through a continuous shear‐flow reaction were used as fillers for virgin natural rubber. A Horikx plot and the gel fraction proved that both main‐chain scission and crosslink scission occurred during the devulcanization. The cure characteristics, swelling behavior, crosslink density, and mechanical properties were studied. GRP and Dev.R, generated from passenger car and light truck tires, showed applicable mechanical properties in the new rubber compounds, and the compounds containing Dev.R demonstrated better properties than those containing GRP. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 208–217, 2005     

Improvement of mechanical properties of rubber compounds using waste rubber/virgin rubber

Ground rubber powder (GRP) and devulcanized rubber waste obtained using the process of continuous shear flow reaction were used as both fillers and a part of rubber in virgin natural rubber (NR). The cure characteristics, swelling behavior, cross‐link density, mechanical properties, and morphology were studied in our laboratory. The GRP and devulcanized rubber, which were generated from passenger car and light truck tires, showed applicable mechanical properties in new rubber compounds, and the compounds that contained devulcanized rubber showed better properties than those with GRP. In particular, devulcanized rubber as a part of rubber obtained through a cross‐link reaction exhibited excellent mechanical properties, with a strong potential for future applications. POLYM. ENG. SCI., 45:1239–1246, 2005. © 2005 Society of Plastics Engineers     

Social virtual world continuance among teens: uncovering the moderating role of perceived aggregate network exposure

Engagement in virtual worlds has become pervasive, particularly among the young. At the same time, the number of virtual environments has increased rapidly. Due to intensifying competition, promoting sustained usage, i.e. continuance, has become a top priority for virtual world operators. Prior research has shown that network externalities play a key role in the adoption of communication technologies. However, a small amount of research has examined the role of network externalities in continued IT usage in general or with respect to the virtual world participation in particular. To fill in this gap, we examine how perceived network externalities affect the continuance of social virtual worlds. To this end, we introduce the concept of perceived aggregate network exposure (PANE). We extend the original information systems (IS) continuance model with perceived enjoyment and position PANE as a moderator. We test the model with data collected from 2134 Finnish Habbo Hotel users and employ structural equation modelling in the analysis. The results demonstrate that PANE moderates the influence of motivational factors on continued use intention and satisfaction.     

Influence of OSC material on the behaviour of metallic Pd catalysts in C2H4 and CO oxidation as well as in NO reduction

Topics in Catalysis - The interaction of CO, C2H4, O2, and NO reaction gas compounds over the metallic Pd/Al2O3 and Pd/OSC/Al2O3 monoliths was investigated in order to understand the behaviour of...     

Synthesis and characterization of new bimetallic transition metal oxynitrides: MI-MII-O-N (MI,MII=V,Mo, W and Nb)

A new class of materials, M_I-M_II-O-N (where M_I, M_II = V, Mo, W, and Nb), has been synthesized by nitriding bimetallic oxide precursors with ammonia gas via a temperature programmed reaction. The oxide precursors are prepared by conventional solid state reaction between two appropriate monometallic oxides. The synthesis of the oxynitrides involves passing NH₃ gas over the oxide precursors at a flow rate of 6.80×10² mols^–1 (1000 cm³ min^–1), and raising the temperature at a rate of 8.3×10^–2 Ks^–1 (5K min^–1) to a final temperature which is held constant for a short period of time. The oxynitrides thus obtained are pyrophoric and need to be passivated before exposing them to air. All these new bimetallic oxynitrides have a face centered cubic (f.c.c.) metal arrangement and high values of surface area. Their surface activity is assessed from their ability to chemisorb CO.     

The process of electrochemical deposition of zinc in the presence of boron-doped detonation nanodiamonds

The influence of detonation of nanodiamonds doped with boron during the detonation synthesis (DND-boron) on the process of electrochemical deposition of zinc from a zincate electrolytic solution is investigated. It is shown that the throwing power (the coating uniformity) increases 2to 4-fold depending on the DND–boron concentration, the electrolytic conductivity remains unchanged, the corrosion resistance (as measured by the corrosion currents) of the Zn–DND-boron coating grows 2.6 times when tested in the 3% NaCl solution and 3 times in the climatic chamber.     

GABAergic cells are the major postsynaptic targets of mossy fibers in the rat hippocampus

Dentate granule cells communicate with their postsynaptic targets by three distinct terminal types. These include the large mossy terminals, filopodial extensions of the mossy terminals, and smaller en passant synaptic varicosities. We examined the postsynaptic targets of mossy fibers by combining in vivo intracellular labeling of granule cells, immunocytochemistry, and electron microscopy. Single granule cells formed large, complex "mossy" synapses on 11-15 CA3 pyramidal cells and 7-12 hilar mossy cells. In contrast, GABAergic interneurons, identified with immunostaining for substance P-receptor, parvalbumin, and mGluR1a-receptor, were selectively innervated by very thin (filopodial) extensions of the mossy terminals and by small en passant boutons in both the hilar and CA3 regions. These terminals formed single, often perforated, asymmetric synapses on the cell bodies, dendrites, and spines of GABAergic interneurons. The number of filopodial extensions and small terminals was 10 times larger than the number of mossy terminals. These findings show that in contrast to cortical pyramidal neurons, (1) granule cells developed distinct types of terminals to affect interneurons and pyramidal cells and (2) they innervated more inhibitory than excitatory cells. These findings may explain the physiological observations that increased activity of granule cells suppresses the overall excitability of the CA3 recurrent system and may form the structural basis of the target-dependent regulation of glutamate release in the mossy fiber system.     

Effects of transdermal nitroglycerin on impedance to flow in the uterine, umbilical, and fetal middle cerebral arteries in pregnancies complicated by preeclampsia and intrauterine growth retardation

BACKGROUND: Uncertainty exists about the extent and consequences of a return to alcohol consumption after liver transplantation for alcoholic liver disease (ALD). AIMS: To determine the prevalence and consequences of alcohol consumption in patients transplanted for ALD. METHODS: A retrospective case controlled study of all patients transplanted for ALD at the Queen Elizabeth Hospital, Birmingham, between 1987 and 1996. RESULTS: Seventy patients with ALD were transplanted, of which 59 survived more than three months; 56 were interviewed. Twenty eight had consumed some alcohol after transplantation; for the nine "heavy drinkers" (HD), the median time to resumption of alcohol intake was six months and for the 19 "moderate drinkers" (MD) it was eight months. There was no significant difference in episodes of acute rejection or compliance with medication between those who were abstinent, MD, or HD. Histological evidence of liver injury was common in ALD patients who had returned to drink. Mild fatty change was found in 1/11 biopsy specimens from abstinent patients but moderate to severe fatty change and ballooned hepatocytes were seen in 3/5 MD and 2/5 HD specimens. Two HD patients had early fibrosis. One HD patient had died of alcohol related complications. CONCLUSIONS: Moderate to heavy alcohol consumption occurs in patients transplanted for ALD. Patient recall of abstinence advice is unreliable, and patients return to alcohol mainly within the first year after liver transplantation. Return to alcohol consumption after liver transplantation is associated with rapid development of histological liver injury including fibrosis.