970 research outputs found

    Acute Ethanol Administration Rapidly Increases Phosphorylation of Conventional Protein Kinase C in Specific Mammalian Brain Regions in Vivo

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    Background Protein kinase C (PKC) is a family of isoenzymes that regulate a variety of functions in the central nervous system including neurotransmitter release, ion channel activity, and cell differentiation. Growing evidence suggests that specific isoforms of PKC influence a variety of behavioral, biochemical, and physiological effects of ethanol in mammals. The purpose of this study was to determine whether acute ethanol exposure alters phosphorylation of conventional PKC isoforms at a threonine 674 (p-cPKC) site in the hydrophobic domain of the kinase, which is required for its catalytic activity. Methods Male rats were administered a dose range of ethanol (0, 0.5, 1, or 2 g/kg, intragastric) and brain tissue was removed 10 minutes later for evaluation of changes in p-cPKC expression using immunohistochemistry and Western blot methods. Results Immunohistochemical data show that the highest dose of ethanol (2 g/kg) rapidly increases p-cPKC immunoreactivity specifically in the nucleus accumbens (core and shell), lateral septum, and hippocampus (CA3 and dentate gyrus). Western blot analysis further showed that ethanol (2 g/kg) increased p-cPKC expression in the P2 membrane fraction of tissue from the nucleus accumbens and hippocampus. Although p-cPKC was expressed in numerous other brain regions, including the caudate nucleus, amygdala, and cortex, no changes were observed in response to acute ethanol. Total PKC? immunoreactivity was surveyed throughout the brain and showed no change following acute ethanol injection

    Structure of the C-terminal domain of the Prokaryotic Sodium Channel Orthologue NsvBa

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    Crystallographic and electrophysiological studies have recently provided insight into the structure, function and drug binding of prokaryotic sodium channels. These channels exhibit significant sequence identities, especially in their transmembrane regions, with human voltage-gated sodium channels. However, rather than being single polypeptides with four homologous domains, they are tetramers of single domain polypeptides, with a C-terminal domain (CTD) composed of an inter-subunit four helix coiled-coil. The structures of the CTDs differ between orthologues. In NavBh and NavMs, the C-termini form a disordered region adjacent to the final transmembrane helix, followed by a coiled-coil region, as demonstrated by synchrotron radiation circular dichroism (SRCD) and double electron-electron resonance electron paramagnetic resonance spectroscopic measurements. In contrast, in the crystal structure of the NavAe orthologue, the entire C-terminus is comprised of a helical region followed by a coiled-coil. In this study we have examined the CTD of the NsvBa from Bacillus alcalophilus, which unlike other orthologues is predicted by different methods to have different types of structures: either a disordered adjacent to the transmembrane region, followed by a helical coiled-coil, or a fully helical CTD. To discriminate between the two possible structures we have used SRCD spectroscopy to experimentally determine the secondary structure of the C-terminus of this orthologue and used the results as the basis for modelling the transition between open and closed conformations of the channel

    The DNA Repair Gene APE1 T1349G Polymorphism and Risk of Gastric Cancer in a Chinese Population

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    Background: Apurinic/apyrimidinic endonuclease 1 (APE1) has a central role in the repair of apurinic apyrimidic sites through both its endonuclease and its phosphodiesterase activities. A common APE1 polymorphism, T1349G (rs3136820), was previously shown to be associated with the risk of cancers. Objective: We hypothesized that the APE1 T1349G polymorphism is also associated with risk of gastric cancer. Methods: In a hospital-based case-control study of 338 case patients with newly diagnosed gastric cancer and 362 cancerfree controls frequency-matched by age and sex, we genotyped the T1349G polymorphism and assessed its associations with risk of gastric cancer. Results: Compared with the APE1 TT genotype, individuals with the variant TG/GG genotypes had a significantly increased risk of gastric cancer (odds ratio = 1.69, 95 % confidence interval = 1.19–2.40), which was more pronounced among subgroups of aged #60 years, male, ever smokers, and ever drinkers. Further analyses revealed that the variant genotypes were associated with an increased risk for diffuse-type, low depth of tumor infiltration (T1 and T2), and lymph node metastasis gastric cancer. Conclusions: The APE1 T1349G polymorphism may be a marker for the development of gastric cancer in the Chinese population. Larger studies are required to validate these findings in diverse populations

    Full-length structural model of RET3 and SEC21 in COPI: identification of binding sites on the appendage for accessory protein recruitment motifs

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    COPI, a 600 kD heptameric complex (consisting of subunits α, β, γ, δ, ε, ζ, and β′) “coatomer,” assembles non-clathrin-coated vesicles and is responsible for intra-Golgi and Golgi-to-ER protein trafficking. Here, we report the three-dimensional structures of the entire sequences of yeast Sec21 (γ-COPI mammalian ortholog), yeast Ret3 (ζ-COPI mammalian ortholog), and the results of successive molecular dynamics investigations of the subunits and assembly based on a protein–protein docking experiment. The three-dimensional structures of the subunits in their complexes indicate the residues of the two subunits that impact on assembly, the conformations of Ret3 and Sec21, and their binding orientations in the complexed state. The structure of the appendage domain of Sec21, with its two subdomains—the platform and the β-sandwich, was investigated to explore its capacity to bind to accessory protein recruitment motifs. Our study shows that a binding site on the platform is capable of binding the Eps15 DPF and epsin DPW2 peptides, whereas the second site on the platform and the site on the β-sandwich subdomain were found to selectively bind to the amphiphysin FXDXF and epsin DPW1 peptides, respectively. Identifying the regions of both the platform and sandwich subdomains involved in binding each peptide motif clarifies the mechanism through which the appendage domain of Sec21 engages with the accessory proteins during the trafficking process of non-clathrin-coated vesicles

    Symmetrical Corticobasal Syndrome Caused by a Novel c.314dup Progranulin Mutation

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    Corticobasal syndrome (CBS) is characterised by asymmetrical parkinsonism and cognitive impairment. The underlying pathology varies between corticobasal degeneration, progressive supranuclear palsy, Alzheimer’s disease, Creutzfeldt–Jakob disease and frontotemporal lobar degeneration sometimes in association with GRN mutations. A 61-year-old male underwent neurological examination, neuropsychological assessment, MRI, and HMPAO-SPECT at our medical centre. After his death at the age of 63, brain autopsy, genetic screening and mRNA expression analysis were performed. The patient presented with slow progressive walking disabilities, non-fluent language problems, behavioural changes and forgetfulness. His family history was negative. He had primitive reflexes, rigidity of his arms and postural instability. Later in the disease course he developed dystonia of his left leg, pathological crying, mutism and dysphagia. Neuropsychological assessment revealed prominent ideomotor and ideational apraxia, executive dysfunction, non-fluent aphasia and memory deficits. Neuroimaging showed symmetrical predominant frontoparietal atrophy and hypoperfusion. Frontotemporal lobar degeneration (FTLD)-TDP type 3 pathology was found at autopsy. GRN sequencing revealed a novel frameshift mutation c.314dup, p.Cys105fs and GRN mRNA levels showed a 50% decrease. We found a novel GRN mutation in a patient with an atypical (CBS) presentation with symmetric neuroimaging findings. GRN mutations are an important cause of CBS associated with FTLD-TDP type 3 pathology, sometimes in sporadic cases. Screening for GRN mutations should also be considered in CBS patients without a positive family history

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    X-ray emission from the Sombrero galaxy: discrete sources

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    We present a study of discrete X-ray sources in and around the bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival Chandra observations with a total exposure of ~200 ks. With a detection limit of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30 kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray binaries (LMXBs). We quantify the differential luminosity functions (LFs) for both the detected GC and field LMXBs, whose power-low indices (~1.1 for the GC-LF and ~1.6 for field-LF) are consistent with previous studies for elliptical galaxies. With precise sky positions of the GCs without a detected X-ray source, we further quantify, through a fluctuation analysis, the GC LF at fainter luminosities down to 1E35 erg/s. The derived index rules out a faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent findings in several elliptical galaxies and the bulge of M31. On the other hand, the 2-6 keV unresolved emission places a tight constraint on the field LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101 sources in the halo of Sombrero. The presence of these sources cannot be interpreted as galactic LMXBs whose spatial distribution empirically follows the starlight. Their number is also higher than the expected number of cosmic AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray surveys. We suggest that either the cosmic X-ray background is unusually high in the direction of Sombrero, or a distinct population of X-ray sources is present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

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    The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO
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