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Reduced pH (reduced + ph)
Selected AbstractsCharacterization of VR1 within the BMBF-Leitproject: ,Molecular Pain Research'JOURNAL OF NEUROCHEMISTRY, Issue 2003R. Jostock The vanilloid receptor VR1 is a ligand, heat and proton gated ion channel, expressed predominantly by primary sensory neurons. We show the molecular characterization of VR1 and its involvement in nociceptive behavior. Biochemical analysis of VR1 showed glycosylation at N604 and the predicted tetrameric structure. Reduced pH potentiated the gating of the receptor by NADA and anandamide in recombinant VR1. Acidification could sensitize VR1 and lead to hyperalgesia. Therefore, the VR1 antagonist capsazepine was tested in several animal models. Capsazepine reduced formalin induced nocifensive behavior and CFA induced mechanical hyperalgesia, and was antiallodynic and antihyperalgesic in animal models of neuropathic pain. VR1 antisense oligonucleotides inhibited VR1 expression in vitro and reduced tactile allodynia in vivo. In conclusion, we could provide evidence for a role of VR1 in inflammatory and neuropathic pain pathways. [source] Effects of acidification on the breeding ecology of a stream-dependent songbird, the Louisiana waterthrush (Seiurus motacilla)FRESHWATER BIOLOGY, Issue 11 2008ROBERT S. MULVIHILL Summary 1.,We compared breeding ecology of the Louisiana waterthrush (Seiurus motacilla) on acidified and circumneutral streams in the Appalachian Highlands of Southwestern Pennsylvania from 1996 to 2005. 2.,Headwater streams impacted by acid mine drainage and/or acidic precipitation showed reduced pH (range 4.5,5.5) compared to four circumneutral streams (pH c. 7). Acid-sensitive taxa, including most mayflies (Ephemeroptera), were almost completely absent from acidified streams, whereas several acid-tolerant taxa, especially stonefly (Plecoptera) genera Leuctra and Amphinemura, were abundant. 3.,Louisiana waterthrush breeding density (c. 1 territory km,1) was significantly reduced on acidified streams compared to circumneutral streams (>2 territories km,1). Territories on acidified streams were almost twice as long as on circumneutral streams. Territories usually were contiguous on circumneutral streams, but they were often disjunct on acidified streams. Breeding density declined on one acidified stream that we studied over a 10-year period. 4.,Clutch initiation was significantly delayed on acidified streams, on average by 9 days in comparison to circumneutral streams, and first-egg dates were inversely related to breeding density. Birds nesting along acidified streams laid smaller clutches, and nestlings had shorter age-adjusted wing lengths. Stream acidity had no effect on nest success or annual fecundity (fledglings/female). However, the number of young fledged km,1 was nearly twice as high on circumneutral streams as on acidified streams. 5.,Acidified streams were characterized by a younger, less site-faithful breeding population. Individuals were less likely to return multiple years to breed, allowing inexperienced breeders to settle on acidified streams. Pairing success was lower on acidified streams, and we observed four cases of waterthrushes emigrating from territories on acidified streams to nearby circumneutral streams in the following year. 6.,We conclude that acidified headwaters constitute lower quality habitat for breeding Louisiana waterthrush. However, breeding birds can apparently compensate for reduced prey resources to fledge young on acidified streams by increasing territory size, foraging in peripheral non-acidified areas, and by provisioning young with novel prey. [source] Employment of stressful conditions during culture production to enhance subsequent cold- and acid-tolerance of bifidobacteriaJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2003J.E. Maus Abstract Aims: This study examined whether exposure of early stationary phase Bifidobacterium longum and B. lactis cells to various combinations of reduced temperature, reduced pH and starvation would enhance the cells' subsequent cold- and/or acid-tolerance. Methods and Results: Survival of B. longum in growth medium at 6°C significantly (P < 0·05) increased as a result of starving cells for 30 or 60 min without any simultaneous decrease in temperature or pH. Acid-tolerance of B. lactis (at pH 3·5 in synthetic gastric fluid) increased significantly when the growth medium pH was decreased from 6·0 to 5·2 and cells experienced 30 or 60 min of starvation. Enhanced B. lactis acid-tolerance persisted through 8,11 weeks of ,80°C storage in the pH 5·2 growth medium. Upon addition to milk during yogurt manufacture, these cells initially had enhanced acid-tolerance relative to untreated cells but untreated cells became equally acid-tolerant during the first 2·5 h of yogurt manufacture. Conclusions: The cold- and acid-tolerance of bifidobacteria vary widely, but may be significantly increased by application of sub-lethal stress to early stationary phase cells during culture production. Significance and Impact of the Study: The enhancement of B. lactis acid-tolerance observed in this study may be of potential importance in the production of effective ready-to-consume probiotic dietary supplements. [source] Insulin-like growth factor (IGF) binding protein-3 regulation of IGF-I is altered in an acidic extracellular environmentJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2001Kimberly E. Forsten While extracellular acidification within solid tumors is well-documented, how reduced pH impacts regulation of insulin-like growth factor-I (IGF-I) has not been studied extensively. Because IGF-I receptor binding is affected by IGF binding proteins (IGFBPs), we examined how pH impacted IGFBP-3 regulation of IGF-I. IGF-I binding in the absence of IGFBP-3 was diminished at reduced pH. Addition of IGFBP-3 reduced IGF-I cell binding at pH 7.4 but increased surface association at pH 5.8. This increase in IGF-I binding at pH 5.8 corresponded with an increase in IGFBP-3 cell association. This, however, was not due to an increase in affinity of IGFBP-3 for heparin at reduced pH although both heparinase III treatment and heparin addition reduced IGFBP-3 enhancement of IGF-I binding. An increase in IGF-I binding to IGFBP-3, though, was seen at reduced pH using a cell-free assay. We hypothesize that the enhanced binding of IGF-I at pH 5.8 is facilitated by increased association of IGFBP-3 at this pH and that the resulting cell associated IGF-I is IGFBP-3 and not IGF-IR bound. Increased internalization and nuclear association of IGF-I at pH 5.8 in the presence of IGFBP-3 was evident, yet cell proliferation was reduced by IGFBP-3 at both pH 5.8 and 7.4 indicating that IGFBP-3-cell associated IGF-I does not signal the cell to proliferate and that the resulting transfer of bound IGF-I from IGF-IR to IGFBP-3 results in diminished proliferation. Solution binding of IGF-I by IGFBP-3 is one means by which IGF-I-induced proliferation is inhibited. Our work suggests that an alternative pathway exists by which IGF-I and IGFBP-3 both associate with the cell surface and that this association inhibits IGF-I-induced proliferation. © 2001 Wiley-Liss, Inc. [source] | ||||||||||