Thermosensory intensity and affect throughout the perceptible range

The thermosensory system was evaluated psychophysically in 12 healthy volunteers, spanning the full range of tolerable temperatures. Subjects provided ratings of (1) perceived thermal intensity, (2) perceived pleasantness or unpleasantness, and (3) perceived pain intensity after placing either one hand or foot in a temperature controlled water bath. Of particular interest were the interrelationships among the three perceptual measures, and differences between heat and cold. The relationship between perceived intensity and (un)pleasantness was different for hot vs cold stimuli. Specifically, for a given perceived thermal intensity, cold stimuli were rated as less pleasant or more unpleasant than hot stimuli. Similarly, for a given pain intensity, cold stimuli were rated as more unpleasant than hot stimuli. As warm temperatures increased and as cold temperatures decreased, stimuli were perceived as being unpleasant before they were perceived as being painful. The difference in transition temperatures for unpleasantness vs pain for heat averaged 1.4 degrees C, while the same difference for cold averaged 5.6 degrees C. Thus, there was a fourfold difference in the range of unpleasant but non-painful cold vs hot temperatures. Pain intensity and unpleasantness ratings were significantly higher for heat stimuli applied to the foot vs hand. In contrast, there was no significant body site difference for pain intensity or unpleasantness ratings of cold stimuli. All of these results reveal important differences in the processing of cold vs hot stimuli. These differences could be exploited to differentiate processing relevant to discriminative vs affective components of somesthetic perception, in both the innocuous and noxious ranges.     

Modulatory effect of copper on nonenzymatic antioxidants in freshwater fish Channa punctatus (Bloch.)

Effect of the low level of copper exposure on nonenzymatic antioxidants was studied in a freshwater fish Channa punctatus (Bloch.). Fish were exposed to cupric chloride at the concentration of 10 ppb for 4 wk (28 d) in a static culture condition. Copper significantly (p < 0.001) increased the serum ceruloplasmin level and total iron-binding capacity. A significant (p < 0.05) increase in reduced glutathione level was recorded in all of the tissues. With regard to nonprotein thiols, copper decreased their level in the liver, but increased it in the gill. The protein-bound thiols remained unaltered except for an increase in the liver. Metallothionein (MT) induction was observed in liver only. Copper exposure had no significant effect on the ascorbic acid level and induced no lipid peroxidation over control values. It is suggested that by modulating the ceruloplasmin level, copper indirectly protects the fish, as it facilitates conversion of pro-oxidant iron to nonoxidant iron. It also induces an array of antioxidants that may be beneficial to fish in the case of oxidative stress resulting from chemical pollutants.     

Elevated levels of serum alpha(2) macroglobulin in wild black bears during hibernation

Bear serum alpha(2) macroglobulin (alpha(2)M) was purified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and partially characterized by tryptic digestion of alpha(2)M and analysis of the peptides by peptide mass fingerprinting. The molecular weight of bear serum alpha(2)M was 181 kDa, same as for human serum alpha(2)M, on SDS-PAGE. However, the MALDI mass spectrum of the tryptic digested bear serum alpha(2)M showed that it is different from human alpha(2)M or other data bank proteins. Liquid chromatography (LC)/mass spectrometry (MS)/MS of the proteolytic products of bear serum alpha(2)M showed eight peptides that had similarities to human alpha(2)M suggesting that the protein of interest was indeed alpha(2)M of bear. The polyclonal antibody against bear serum alpha(2)M recognized only one protein from the western blot of bear serum proteins. It also recognized human alpha(2)M. The levels of serum alpha(2)M were significantly increased during hibernating state as compared to active state of bears indicating its protective role from the consequences of the metabolic depression during hibernation.     

Effects of some flavonoids on the susceptibility of low-density lipoprotein to oxidative modification

The effects of six flavonoids viz., apigenin, genistein, morin, naringin, pelargonidin and quercetin on the susceptibility of low-density lipoprotein (LDL) to oxidative modification were investigated. Flavonoids were added to plasma and incubated for 3 hr at 37 degrees C, and the LDL fraction was separated by ultracentrifugation. Oxidizability of LDL was estimated by measuring conjugated diene (CD), lipid peroxides and thiobarbituric acid-reactive substances (TBARS), after cupric sulfate solution was added. Quercetin and morin significantly (P<0.01 by ANOVA) prolonged the lag time before initiation of oxidation reaction in dose-dependent manner. They also suppressed the formation of lipid peroxides and TBARS more markedly than other flavonoids. The ability to prolong lag time and suppression of lipid peroxides and TBARS formation was in the following order: quercetin >morin >pelargonidin >genistein >naringin >apigenin. LDL exposed to flavonoids reduced oxidizability. These findings suggest that flavonoids may have a role in ameliorating atherosclerosis.     

Mutations of MYO6 are associated with recessive deafness,DFNB37

Cosegregation of profound, congenital deafness with markers on chromosome 6q13 in three Pakistani families defines a new recessive deafness locus, DFNB37. Haplotype analyses reveal a 6-cM linkage region, flanked by markers D6S1282 and D6S1031, that includes the gene encoding unconventional myosin VI. In families with recessively inherited deafness, DFNB37, our sequence analyses of MYO6 reveal a frameshift mutation (36-37insT), a nonsense mutation (R1166X), and a missense mutation (E216V). These mutations, along with a previously published missense allele linked to autosomal dominant progressive hearing loss (DFNA22), provide an allelic spectrum that probes the relationship between myosin VI dysfunction and the resulting phenotype.     

Death receptor activation complexes: it takes two to activate TNF receptor 1

The extrinsic pathway of apoptosis originates at the membrane and engages membrane death receptors. Tumor necrosis factor receptor 1 (TNF-R1) is a death receptor that transduces both the death and survival signals but the molecular mechanisms via which TNF-R1 mediates these signals remain poorly understood. Recently, it has been reported that the TNF-R1 transduces these signals via two signaling complexes. The first complex (complex I) is formed at the membrane by TNF-R1, TRADD, RIP, TRAF2 and c-IAP1, while the second complex (complex II), formed in the cytosol, predominantly contains FADD and pro-caspases 8/10 but lacks TNF-R1. Complex I is responsible for activating NF-kappaB and thus, the transduction of survival signals. Complex II, on the other hand, is reported to transduce the apoptotic signals and it does so only if NF-kappaB is unable to promote upregulation of the anti-apoptotic FLIPL. These findings highlighting the complexities of TNF-R1-mediated signaling events are likely to further the progress in the constantly evolving area of death receptor-dependent signaling pathways.     

Mutations in a novel gene,TMIE, are associated with hearing loss linked to the DFNB6 locus

We have identified five different homozygous recessive mutations in a novel gene, TMIE (transmembrane inner ear expressed gene), in affected members of consanguineous families segregating severe-to-profound prelingual deafness, consistent with linkage to DFNB6. The mutations include an insertion, a deletion, and three missense mutations, and they indicate that loss of function of TMIE causes hearing loss in humans. TMIE encodes a protein with 156 amino acids and exhibits no significant nucleotide or deduced amino acid sequence similarity to any other gene.     

Oligomerization of wild type and nonfunctional mutant angiotensin II type I receptors inhibits galphaq protein signaling but not ERK activation

The 7-transmembrane or G protein-coupled receptors relay signals from hormones and sensory stimuli to multiple signaling systems at the intracellular face of the plasma membrane including heterotrimeric G proteins, ERK1/2, and arrestins. It is an emerging concept that 7-transmembrane receptors form oligomers; however, it is not well understood which roles oligomerization plays in receptor activation of different signaling systems. To begin to address this question, we used the angiotensin II type 1 (AT(1)) receptor, a key regulator of blood pressure and fluid homeostasis that in specific context has been described to activate ERKs without activating G proteins. By using bioluminescence resonance energy transfer, we demonstrate that AT(1) receptors exist as oligomers in transfected COS-7 cells. AT(1) oligomerization was both constitutive and receptor-specific as neither agonist, antagonist, nor co-expression with three other receptors affected the bioluminescence resonance energy transfer 2 signal. Furthermore, the oligomerization occurs early in biosynthesis before surface expression, because we could control AT(1) receptor export from the endoplasmic reticulum or Golgi by using regulated secretion/aggregation technology (RPD trade mark ). Co-expression studies of wild type AT(1) and AT(1) receptor mutants, defective in either ligand binding or G protein and ERK activation, yielded an interesting result. The mutant receptors specifically exerted a dominant negative effect on Galpha(q) activation, whereas ERK activation was preserved. These data suggest that distinctly active conformations of AT(1) oligomers can couple to each of these signaling systems and imply that oligomerization plays an active role in supporting these distinctly active conformations of AT(1) receptors.