148 research outputs found

    Thermophysics of metal alkanoates I. Heat capacities and thermodynamic properties of sodium methanoate and ethanoate

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    The heat capacities of two sodium alkanoates have been studied by adiabatic calorimetry. Earlier measurements from this laboratory on sodium methanoate between 5 and 350 K are supplemented from 300 K to melting. Sodium ethanoate ismeasured from 7 through 350 K; the results differ markedly from those reported by Strelkov in that we find the 21 K transition peak is much larger and the higher temperature values are 15 to 20 per cent higher and in good accord with reported d.s.c. studies at still higher temperatures. We estimate [Delta]traSmo/R of the 21 K peak to be about 1.5 although no isostructural lattice contribution is available. Even with adjuvant X-ray diffraction results by Hsu and Nordman the mechanism of the transition has not been identified. The 298.15 K values of Cp,m/R, Smo/R, {Hmo-Hmo(0)}/R and {Gmo-Hmo(0)}/RT are 12.127, 16.610, 2308.1 K, and -8.868 for form II CH3COONa.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25417/1/0000866.pd

    Thermophysical properties of the lanthanide sesquisulfides. II. Schottky contributions and magnetic and electronic properties of γ‐phase Pr2S3, Tb2S3, and Dy2S3

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    Heat‐capacity measurements by adiabatic equilibrium calorimetry are reported for γ‐phase Pr2S3, Tb2S3, and Dy2S3 between 5 and 350 K. Highly purified samples were prepared and their composition verified by chemical analysis. Precision lattice parameters were determined for each compound and are compared with literature values. The total heat capacity has been resolved into lattice, magnetic, and Schottky components by a volumetric approach. The experimental Schottky contributions accord with the calculated curves based on the crystal‐field splitting of the 2S+1LJ ground state of the lanthanide ions occupying sites of S4 symmetry in the Th3P4 lattice. The individual crystal‐field electronic energy levels have been obtained in part from an analysis of the hot‐band data observed in the absorption spectra of Pr2S3, Tb2S3, and Dy2S3, and from a calculated splitting in which the crystal‐field parameters Bkm, were determined from a lattice‐sum calculation. Molar thermodynamic properties are reported for all three compounds. The entropy at 298.15 K {S0−S0 (7 K)}, is 22.78R, 22.93R, and 23.36R, for γ‐phase Pr2S3, Tb2S3, and Dy2S3, respectively.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70592/2/JCPSA6-95-3-1964-1.pd

    A novel device to measure power grip forces in squirrel monkeys

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    Understanding the neural bases for grip force behaviors in both normal and neurologically impaired animals is imperative prior to improving treatments and therapeutic approaches. The present paper describes a novel device for the assessment of power grip forces in squirrel monkeys. The control of grasping and object manipulation represents a vital aspect of daily living by allowing the performance of a wide variety of complex hand movements. However, following neurological injury such as stroke, these grasping behaviors are often severely affected, resulting in persistent impairments in strength, grip force modulation and kinematic hand control. While there is a significant clinical focus on rehabilitative strategies to address these issues, there exists the need for translational animal models. In the study presented here, we describe a simple grip force device designed for use in nonhuman primates, which provides detailed quantitative information regarding distal grip force dynamics. Adult squirrel monkeys were trained to exceed a specific grip force threshold, which was rewarded with a food pellet. One of these subjects then received an infarct of the M1 hand representation area. Results suggest that the device provides detailed and reliable information on grip behaviors in healthy monkeys and can detect deficits in grip dynamics in monkeys with cortical lesions (significantly longer release times). Understanding the physiological and neuroanatomical aspects of grasping function following neurological injury may lead to more effective rehabilitative interventions

    B Cells Migrate into Remote Brain Areas and Support Neurogenesis and Functional Recovery after Focal Stroke in Mice

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    Lymphocytes infiltrate the stroke core and penumbra and often exacerbate cellular injury. B cells, however, are lymphocytes that do not contribute to acute pathology but can support recovery. B cell adoptive transfer to mice reduced infarct volumes 3 and 7 d after transient middle cerebral artery occlusion (tMCAo), independent of changing immune populations in recipient mice. Testing a direct neurotrophic effect, B cells cocultured with mixed cortical cells protected neurons and maintained dendritic arborization after oxygen-glucose deprivation. Whole-brain volumetric serial two-photon tomography (STPT) and a custom-developed image analysis pipeline visualized and quantified poststroke B cell diapedesis throughout the brain, including remote areas supporting functional recovery. Stroke induced significant bilateral B cell diapedesis into remote brain regions regulating motor and cognitive functions and neurogenesis (e.g., dentate gyrus, hypothalamus, olfactory areas, cerebellum) in the whole-brain datasets. To confirm a mechanistic role for B cells in functional recovery, rituximab was given to human CD20+ (hCD20+) transgenic mice to continuously deplete hCD20+-expressing B cells following tMCAo. These mice experienced delayed motor recovery, impaired spatial memory, and increased anxiety through 8 wk poststroke compared to wild type (WT) littermates also receiving rituximab. B cell depletion reduced stroke-induced hippocampal neurogenesis and cell survival. Thus, B cell diapedesis occurred in areas remote to the infarct that mediated motor and cognitive recovery. Understanding the role of B cells in neuronal health and disease-based plasticity is critical for developing effective immune-based therapies for protection against diseases that involve recruitment of peripheral immune cells into the injured brain

    Potential conservation of circadian clock proteins in the phylum Nematoda as revealed by bioinformatic searches

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    Although several circadian rhythms have been described in C. elegans, its molecular clock remains elusive. In this work we employed a novel bioinformatic approach, applying probabilistic methodologies, to search for circadian clock proteins of several of the best studied circadian model organisms of different taxa (Mus musculus, Drosophila melanogaster, Neurospora crassa, Arabidopsis thaliana and Synechoccocus elongatus) in the proteomes of C. elegans and other members of the phylum Nematoda. With this approach we found that the Nematoda contain proteins most related to the core and accessory proteins of the insect and mammalian clocks, which provide new insights into the nematode clock and the evolution of the circadian system.Fil: Romanowski, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; ArgentinaFil: Garavaglia, Matías Javier. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Ing.genética y Biolog.molecular y Celular. Area Virus de Insectos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Goya, María Eugenia. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ghiringhelli, Pablo Daniel. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Ing.genética y Biolog.molecular y Celular. Area Virus de Insectos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Golombek, Diego Andres. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Cronobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    A randomised controlled trial evaluating family mediated exercise (FAME) therapy following stroke

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    <p>Abstract</p> <p>Background</p> <p>Stroke is a leading cause of disability among adults worldwide. Evidence suggests that increased duration of exercise therapy following stroke has a positive impact on functional outcome following stroke. The main objective of this randomised controlled trial is to evaluate the impact of additional family assisted exercise therapy in people with acute stroke.</p> <p>Methods/Design</p> <p>A prospective multi-centre single blind randomised controlled trial will be conducted. Forty patients with acute stroke will be randomised into either an experimental or control group. The experimental group will receive routine therapy and additional lower limb exercise therapy in the form of family assisted exercises. The control group will receive routine therapy with no additional formal input from their family members. Participants will be assessed at baseline, post intervention and followed up at three months using a series of standardised outcome measures. A secondary aim of the project is to evaluate the impact of the family mediated exercise programme on the person with stroke and the individual(s) assisting in the delivery of exercises using a qualitative methodology. The study has gained ethical approval from the Research Ethics Committees of each of the clinical sites involved in the study.</p> <p>Discussion</p> <p>This study will evaluate a structured programme of exercises that can be delivered to people with stroke by their 'family members/friends'. Given that the progressive increase in the population of older people is likely to lead to an increased prevalence of stroke in the future, it is important to reduce the burden of this illness on the individual, the family and society. Family mediated exercises can maximise the carry over outside formal physiotherapy sessions, giving patients the opportunity for informal practice.</p> <p>Trial Registration</p> <p>The protocol for this study is registered with the US NIH Clinical trials registry (NCT00666744)</p

    Correction: Pulsed moxifloxacin for the prevention of exacerbations of chronic obstructive pulmonary disease: a randomized controlled trial

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    BACKGROUND: Acute exacerbations contribute to the morbidity and mortality associated with chronic obstructive pulmonary disease (COPD). This proof-of-concept study evaluates whether intermittent pulsed moxifloxacin treatment could reduce the frequency of these exacerbations. METHODS: Stable patients with COPD were randomized in a double-blind, placebo-controlled trial to receive moxifloxacin 400 mg PO once daily (N = 573) or placebo (N = 584) once a day for 5 days. Treatment was repeated every 8 weeks for a total of six courses. Patients were repeatedly assessed clinically and microbiologically during the 48-week treatment period, and for a further 24 weeks' follow-up. RESULTS: At 48 weeks the odds ratio (OR) for suffering an exacerbation favoured moxifloxacin: per-protocol (PP) population (N = 738, OR 0.75, 95% confidence interval (CI) 0.565-0.994, p = 0.046), intent-to-treat (ITT) population (N = 1149, OR 0.81, 95% CI 0.645-1.008, p = 0.059), and a post-hoc analysis of per-protocol (PP) patients with purulent/mucopurulent sputum production at baseline (N = 323, OR 0.55, 95% CI 0.36-0.84, p = 0.006).There were no significant differences between moxifloxacin and placebo in any pre-specified efficacy subgroup analyses or in hospitalization rates, mortality rates, lung function or changes in St George's Respiratory Questionnaire (SGRQ) total scores. There was, however, a significant difference in favour of moxifloxacin in the SGRQ symptom domain (ITT: -8.2 vs -3.8, p = 0.009; PP: -8.8 vs -4.4, p = 0.006). Moxifloxacin treatment was not associated with consistent changes in moxifloxacin susceptibility. There were more treatment-emergent, drug related adverse events with moxifloxacin vs placebo (p < 0.001) largely due to gastrointestinal events (4.7% vs 0.7%). CONCLUSIONS: Intermittent pulsed therapy with moxifloxacin reduced the odds of exacerbation by 20% in the ITT population, by 25% among the PP population and by 45% in PP patients with purulent/mucopurulent sputum at baseline. There were no unexpected adverse events and there was no evidence of resistance development. TRIAL REGISTRATION: ClinicalTrials.gov number, NCT00473460 (ClincalTrials.gov)

    Immunotherapy of pediatric brain tumor patients should include an immunoprevention strategy: a medical hypothesis paper

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    Adults diagnosed with Glioblastoma multiforme (GBM) are frequently faced with a 7% chance of surviving 2 years compared with pediatric patients with GBM who have a 26% survival rate. Our recent screen of possible glioma-associated antigen precursor protein (TAPP) profiles displayed from different types of pediatric brain tumors showed that pediatric patients contained a subset of the tumor antigens displayed by adult GBM patients. Adult GBM possess at least 27 tumor antigens that can potentially stimulate T cell immune responses, suggesting that these tumors are quite antigenic. In contrast, pediatric brain tumors only expressed nine tumor antigens with mRNA levels that were equivalent to those displayed by adult GBM. These tumor-associated antigens could be used as possible targets of therapeutic immunization for pediatric brain cancer patients. Children have developing immune systems that peak at puberty. An immune response mounted by these pediatric patients might account for their extended life spans, even though the pediatric brain tumors express far fewer total tumor-associated antigens. Here we present a hypothesis that pediatric brain tumor patients might be the best patients to show that immunotherapy can be used to successfully treat established cancers. We speculate that immunotherapy should include a panel of tumor antigens that might prevent the out-growth of more malignant tumor cells and thereby prevent the brain tumor relapse. Thus, pediatric brain tumor patients might provide an opportunity to prove the concept of immunoprevention

    REVEILLE8 and PSEUDO-REPONSE REGULATOR5 Form a Negative Feedback Loop within the Arabidopsis Circadian Clock

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    Circadian rhythms provide organisms with an adaptive advantage, allowing them to regulate physiological and developmental events so that they occur at the most appropriate time of day. In plants, as in other eukaryotes, multiple transcriptional feedback loops are central to clock function. In one such feedback loop, the Myb-like transcription factors CCA1 and LHY directly repress expression of the pseudoresponse regulator TOC1 by binding to an evening element (EE) in the TOC1 promoter. Another key regulatory circuit involves CCA1 and LHY and the TOC1 homologs PRR5, PRR7, and PRR9. Purification of EE–binding proteins from plant extracts followed by mass spectrometry led to the identification of RVE8, a homolog of CCA1 and LHY. Similar to these well-known clock genes, expression of RVE8 is circadian-regulated with a dawn phase of expression, and RVE8 binds specifically to the EE. However, whereas cca1 and lhy mutants have short period phenotypes and overexpression of either gene causes arrhythmia, rve8 mutants have long-period and RVE8-OX plants have short-period phenotypes. Light input to the clock is normal in rve8, but temperature compensation (a hallmark of circadian rhythms) is perturbed. RVE8 binds to the promoters of both TOC1 and PRR5 in the subjective afternoon, but surprisingly only PRR5 expression is perturbed by overexpression of RVE8. Together, our data indicate that RVE8 promotes expression of a subset of EE–containing clock genes towards the end of the subjective day and forms a negative feedback loop with PRR5. Thus RVE8 and its homologs CCA1 and LHY function close to the circadian oscillator but act via distinct molecular mechanisms
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