The influence of steps on the dissociation of NO on Pt surfaces: Temperature-programmed desorption studies of NO adsorption on Pt{211}

Temperature-programmed desorption (TPD) has been used to investigate the adsorption of NO on Pt{211} at 300 K and 120 K. Results show that NO dissociation occurs readily on Pt{211}, as evidenced by the observation of N-2 and N2O in the TPD spectrum. Following adsorption at 120 K three NO TPD peaks at 338, 416, and 503 K are observed, in agreement with previous observations. In combination with data acquired in a recent reflection absorption infrared spectroscopy and density functional theory investigation of NO/Pt{211}, these peaks are assigned to the desorption of NO from an O-NO complex, the recombinative desorption of N and O atoms, and to desorption of a step-bridged NO species, respectively. These assignments are in disagreement with previous work, where the high-temperature NO peak was assigned to the desorption of step bound NO and the two low-temperature peaks were assigned to the desorption of NO from terrace sites. TPD spectra recorded following adsorption at 300 K, with a heating rate of 1 K s(-1), show similar features to those recorded following 120 K adsorption. This is also in disagreement with previous observations, where only two NO TPD peaks were observed following adsorption at room temperature. This disagreement can be accounted for by the different heating rates used in the two experiments. (C) 2003 American Institute of Physics

Market Allocations under Ambiguity: A Survey

We review some of the (theoretical) economic implications of David Schmeidler's models of decision under uncertainty (Choquet expected utility and maxmin expected utility) in competitive market settings. We start with the portfolio inertia result of Dow and Werlang (1992), show how it does or does not generalize in an equilibrium setting. We further explore the equilibrium implications (indeterminacies, non revelation of information) of these decision models. A section is then devoted to the studies of Pareto optimal arrangements under these models. We conclude with a discussion of experimental evidence for these models that relate, in particular, to the implications for market behaviour discussed in the preceding sections

Alu-miRNA interactions modulate transcript isoform diversity in stress response and reveal signatures of positive selection

Primate-specific Alus harbor different regulatory features, including miRNA targets. In this study, we provide evidence for miRNA-mediated modulation of transcript isoform levels during heat-shock response through exaptation of Alu-miRNA sites in mature mRNA. We performed genome-wide expression profiling coupled with functional validation of miRNA target sites within exonized Alus, and analyzed conservation of these targets across primates. We observed that two miRNAs (miR-15a-3p and miR-302d-3p) elevated in stress response, target RAD1, GTSE1, NR2C1, FKBP9 and UBE2I exclusively within Alu. These genes map onto the p53 regulatory network. Ectopic overexpression of miR-15a-3p downregulates GTSE1 and RAD1 at the protein level and enhances cell survival. This Alu-mediated fine-tuning seems to be unique to humans as evident from the absence of orthologous sites in other primate lineages. We further analyzed signatures of selection on Alu-miRNA targets in the genome, using 1000 Genomes Phase-I data. We found that 198 out of 3177 Alu-exonized genes exhibit signatures of selection within Alu-miRNA sites, with 60 of them containing SNPs supported by multiple evidences (global-FST > 0.3, pair-wise-FST > 0.5, Fay-Wu's H  2.0, high ΔDAF) and implicated in p53 network. We propose that by affecting multiple genes, Alu-miRNA interactions have the potential to facilitate population-level adaptations in response to environmental challenges

Proteomic analysis of HIV-1 Nef cellular binding partners reveals a role for exocyst complex proteins in mediating enhancement of intercellular nanotube formation

<p>Abstract</p> <p>Background</p> <p>HIV-1 Nef protein contributes to pathogenesis via multiple functions that include enhancement of viral replication and infectivity, alteration of intracellular trafficking, and modulation of cellular signaling pathways. Nef stimulates formation of tunneling nanotubes and virological synapses, and is transferred to bystander cells via these intercellular contacts and secreted microvesicles. Nef associates with and activates Pak2, a kinase that regulates T-cell signaling and actin cytoskeleton dynamics, but how Nef promotes nanotube formation is unknown.</p> <p>Results</p> <p>To identify Nef binding partners involved in Pak2-association dependent Nef functions, we employed tandem mass spectrometry analysis of Nef immunocomplexes from Jurkat cells expressing wild-type Nef or Nef mutants defective for the ability to associate with Pak2 (F85L, F89H, H191F and A72P, A75P in NL4-3). We report that wild-type, but not mutant Nef, was associated with 5 components of the exocyst complex (EXOC1, EXOC2, EXOC3, EXOC4, and EXOC6), an octameric complex that tethers vesicles at the plasma membrane, regulates polarized exocytosis, and recruits membranes and proteins required for nanotube formation. Additionally, Pak2 kinase was associated exclusively with wild-type Nef. Association of EXOC1, EXOC2, EXOC3, and EXOC4 with wild-type, but not mutant Nef, was verified by co-immunoprecipitation assays in Jurkat cells. Furthermore, shRNA-mediated depletion of EXOC2 in Jurkat cells abrogated Nef-mediated enhancement of nanotube formation. Using bioinformatic tools, we visualized protein interaction networks that reveal functional linkages between Nef, the exocyst complex, and the cellular endocytic and exocytic trafficking machinery.</p> <p>Conclusions</p> <p>Exocyst complex proteins are likely a key effector of Nef-mediated enhancement of nanotube formation, and possibly microvesicle secretion. Linkages revealed between Nef and the exocyst complex suggest a new paradigm of exocyst involvement in polarized targeting for intercellular transfer of viral proteins and viruses.</p

Polyphosphoinositides suppress the adhesion of Haemophilus influenzae to pharyngeal cells

BACKGROUND: One of the primary causes of otitis media (OM), an inflammation of the middle ear, is the bacterium Haemophilus influenzae (HI). OM often occurs to young children, and is mostly treated with antibiotics. Due to concerns over bacterial resistance toward antibiotics, reliable prophylactic treatments such as administrating anti-adhesion agents are now viewed as viable alternatives. RESULTS: The present study tested the feasibilty of using phosphoinositides as anti-adhesion agents against HI cells. Cells of non-typeable HI were radiolabeled with (111- )indium-oxine, pre-incubated with various individual phosphoinositides for 15 minutes at 37°C, and incubated with a monolayer of human pharynx carcinoma (DT 562) cells for 20 minutes at 37°C. The result showed that at 0.1 mg/mL dipalmitoylphosphatidylinositol-3,4-diphosphate (PI-3,4-PP) had the highest anti-adhesion activity, followed by phosphatidylinositol-3-phosphate (PI-3-P) and phosphatidylinositol-4-phosphate (PI-4-P). The anti-adhesion activity of PI-3,4-PP was dose-dependent ranging from 0.006 to 0.1 mg/mL. In addition, results from an in vivo study demonstrated that pre-incubation of HI cells with PI-3,4-PP at 1 mg/mL suppressed the growth of HI in nasopharynx of neonatal rats. CONCLUSIONS: These findings suggest that PI-3-P and PI-4-P and more so PI-3,4-PP may serve as prophylactic agents against HI adhesion and colonization

Nociceptin/Orphanin FQ receptor expression in clinical pain disorders and functional effects in cultured neurons

The Nociceptin/Orphanin FQ peptide receptor (NOP), activated by its endogenous peptide ligand Nociceptin/Orphanin FQ (N/OFQ), exerts several effects including modulation of pain signalling. We have examined, for the first time, the tissue distribution of the NOP receptor in clinical visceral and somatic pain disorders by immunohistochemistry, and assessed functional effects of NOP and [micro] opioid receptor activation in cultured human and rat dorsal root ganglion (DRG) neurons. Quantification of NOP-positive nerve fibres within the bladder sub-urothelium revealed a remarkable several-fold increase in Detrusor Overactivity (p<0.0001) and Painful Bladder Syndrome patient specimens (p=0.0014), compared to controls. In post-mortem control human DRGs, 75-80% of small/medium neurons (<=50 [micro]m diameter) in the lumbar (somatic) and sacral (visceral) DRG were positive for NOP, and fewer large neurons; avulsion-injured cervical human DRG neurons showed similar numbers. NOP-immunoreactivity was significantly decreased in injured peripheral nerves (p=0.0004), and also in painful neuromas (p=0.025). Calcium imaging studies in cultured rat DRG neurons demonstrated dose-dependent inhibition of capsaicin responses in the presence of N/OFQ, with an IC50 of 8.6 pM. In cultured human DRG neurons, 32% inhibition of capsaicin responses was observed in the presence of 1 pM N/OFQ (p<0.001). The maximum inhibition of capsaicin responses was greater with N/OFQ than [mu]-opioid receptor agonist DAMGO. Our findings highlight the potential of NOP agonists, particularly in urinary bladder overactivity and pain syndromes. The regulation of NOP expression in visceral and somatic sensory neurons by target-derived neurotrophic factors deserves further study, and the efficacy of NOP selective agonists in clinical trials

Molecular analysis of autosomal dominant hereditary ataxias in the Indian population: high frequency of SCA2 and evidence for a common founder mutation

Expansion of CTG/CAG trinucleotide repeats has been shown to cause a number of autosomal dominant cerebellar ataxias (ADCA) such as SCA1, SCA2, SCA3/MJD, SCA6, SCA7, SCA8 and DRPLA. There is a wide variation in the clinical phenotype and prevalence of these ataxias in different populations. An analysis of ataxias in 42 Indian families indicates that SCA2 is the most frequent amongst all the ADCAs we have studied. In the SCA2 families, together with an intergenerational increase in repeat size, a horizontal increase with the birth order of the offspring was also observed, indicating an important role for parental age in repeat instability. This was strengthened by the detection of a pair of dizygotic twins with expanded alleles showing the same repeat number. Haplotype analysis indicates the presence of a common founder chromosome for the expanded allele in the Indian population. Polymorphism of CAG repeats in 135 normal individuals at the SCA loci studied showed similarity to the Caucasian population but was significantly different from the Japanese population

Hierarchical model for the scale-dependent velocity of seismic waves

Elastic waves of short wavelength propagating through the upper layer of the Earth appear to move faster at large separations of source and receiver than at short separations. This scale dependent velocity is a manifestation of Fermat's principle of least time in a medium with random velocity fluctuations. Existing perturbation theories predict a linear increase of the velocity shift with increasing separation, and cannot describe the saturation of the velocity shift at large separations that is seen in computer simulations. Here we show that this long-standing problem in seismology can be solved using a model developed originally in the context of polymer physics. We find that the saturation velocity scales with the four-third power of the root-mean-square amplitude of the velocity fluctuations, in good agreement with the computer simulations.Comment: 7 pages including 3 figure

Early deprivation alters structural brain development from middle childhood to adolescence

Hypotheses concerning the biologic embedding of early adversity via developmental neuroplasticity mechanisms have been proposed on the basis of experimental studies in animals. However, no studies have demonstrated a causal link between early adversity and neural development in humans. Here, we present evidence from a randomized controlled trial linking psychosocial deprivation in early childhood to changes in cortical development from childhood to adolescence using longitudinal data from the Bucharest Early Intervention Project. Changes in cortical structure due to randomization to foster care were most pronounced in the lateral and medial prefrontal cortex and in white matter tracts connecting the prefrontal and parietal cortex. Demonstrating the causal impact of exposure to deprivation on the development of neural structure highlights the importance of early placement into family-based care to mitigate lasting neurodevelopmental consequences associated with early-life deprivation

IGVBrowser–a genomic variation resource from diverse Indian populations

The Indian Genome Variation Consortium (IGVC) project, an initiative of the Council for Scientific and Industrial Research, has been the first large-scale comprehensive study of the Indian population. One of the major aims of the project is to study and catalog the variations in nearly thousand candidate genes related to diseases and drug response for predictive marker discovery, founder identification and also to address questions related to ethnic diversity, migrations, extent and relatedness with other world population. The Phase I of the project aimed at providing a set of reference populations that would represent the entire genetic spectrum of India in terms of language, ethnicity and geography and Phase II in providing variation data on candidate genes and genome wide neutral markers on these reference set of populations. We report here development of the IGVBrowser that provides allele and genotype frequency data generated in the IGVC project. The database harbors 4229 SNPs from more than 900 candidate genes in contrasting Indian populations. Analysis shows that most of the markers are from genic regions. Further, a large fraction of genes are implicated in cardiovascular, metabolic, cancer and immune system-related diseases. Thus, the IGVC data provide a basal level variation data in Indian population to study genetic diseases and pharmacology. Additionally, it also houses data on ∼50 000 (Affy 50 K array) genome wide neutral markers in these reference populations. In IGVBrowser one can analyze and compare genomic variations in Indian population with those reported in HapMap along with annotation information from various primary data sources