818 research outputs found

    Regional differences in the coupling between resting cerebral blood flow and metabolism may indicate action preparedness as a default state.

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    Although most functional neuroimaging studies examine task effects, interest intensifies in the "default" resting brain. Resting conditions show consistent regional activity, yet oxygen extraction fraction constancy across regions. We compared resting cerebral metabolic rates of glucose (CMRgl) measured with 18F-labeled 2-fluoro-2-deoxy-D-glucose to cerebral blood flow (CBF) 15O-H2O measures, using the same positron emission tomography scanner in 2 samples (n = 60 and 30) of healthy right-handed adults. Region to whole-brain ratios were calculated for 35 standard regions of interest, and compared between CBF and CMRgl to determine perfusion relative to metabolism. Primary visual and auditory areas showed coupling between CBF and CMRgl, limbic and subcortical regions--basal ganglia, thalamus and posterior fossa structures--were hyperperfused, whereas association cortices were hypoperfused. Hyperperfusion was higher in left than right hemisphere for most cortical and subcallosal limbic regions, but symmetric in cingulate, basal ganglia and somatomotor regions. Hyperperfused regions are perhaps those where activation is anticipated at short notice, whereas downstream cortical modulatory regions have longer "lead times" for deployment. The novel observation of systematic uncoupling of CBF and CMRgl may help elucidate the potential biological significance of the "default" resting state. Whether greater left hemispheric hyperperfusion reflects lateral dominance needs further examination

    All-Optical Switching with Transverse Optical Patterns

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    We demonstrate an all-optical switch that operates at ultra-low-light levels and exhibits several features necessary for use in optical switching networks. An input switching beam, wavelength λ\lambda, with an energy density of 10210^{-2} photons per optical cross section [σ=λ2/(2π)\sigma=\lambda^2/(2\pi)] changes the orientation of a two-spot pattern generated via parametric instability in warm rubidium vapor. The instability is induced with less than 1 mW of total pump power and generates several μ\muWs of output light. The switch is cascadable: the device output is capable of driving multiple inputs, and exhibits transistor-like signal-level restoration with both saturated and intermediate response regimes. Additionally, the system requires an input power proportional to the inverse of the response time, which suggests thermal dissipation does not necessarily limit the practicality of optical logic devices

    The Biological Effect of Contralateral Forepaw Stimulation in Rat Focal Cerebral Ischemia: A Multispectral Optical Imaging Study

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    Our group has already published the possible neuroprotective effect of contralateral forepaw stimulation in temporary focal ischemia in a study. However, the background is still unclear. In the present study we investigated the possible mechanism by monitoring focal ischemia with multispectral [laser speckle, imaging of intrinsic signals (OIS)] imaging. Sprague–Dawley rats were prepared using 1.2% isoflurane anesthesia. The middle cerebral artery was occluded by photothrombosis (4 mW) and the common carotid artery was ligated permanently. Physiological variables were constantly monitored during the experiment. A 6 × 6 mm area centered 3 mm posterior and 4 mm lateral to Bregma was thinned for laser speckle and OIS imaging. Nine circular regions of interests (0.3 mm in diameter) were evenly spaced on the speckle contrast image for the analysis of peri-infarct flow transients, blood flow, and metabolic changes. Both the sham (n = 7) and forepaw-stimulated animals (n = 7) underwent neurological examinations 24 h after ischemia at which point all animals were sacrificed and the infarct size was determined by triphenyltetrazolium chloride. The physiological variables were in normal range and the experimental protocol did not cause significant differences between groups. Both the neurological scores (sham: 3.6 ± 1.7, stimulated: 4.3 ± 1.4) and the infarct volume (sham: 124 ± 39 mm3, stimulated: 147 ± 47 mm3) did not show significant differences between groups. The forepaw stimulation did not increase the intra-ischemic flow neither over the penumbral or the peri-ischemic area. However, the hemoglobin transients related metabolic load (CMRO2) was significantly lower (p < 0.001) while the averaged number of hyperemic flow transients were significantly (p = 0.013) higher in the forepaw (sham: 3.5 ± 2.2, stimulated: 7.0 ± 2.3) stimulated animals

    The Second Conference on Lunar Bases and Space Activities of the 21st Century, volume 1

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    These papers comprise a peer-review selection of presentations by authors from NASA, LPI industry, and academia at the Second Conference (April 1988) on Lunar Bases and Space Activities of the 21st Century, sponsored by the NASA Office of Exploration and the Lunar Planetary Institute. These papers go into more technical depth than did those published from the first NASA-sponsored symposium on the topic, held in 1984. Session topics covered by this volume include (1) design and operation of transportation systems to, in orbit around, and on the Moon, (2) lunar base site selection, (3) design, architecture, construction, and operation of lunar bases and human habitats, and (4) lunar-based scientific research and experimentation in astronomy, exobiology, and lunar geology

    The Second Conference on Lunar Bases and Space Activities of the 21st Century, volume 2

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    These 92 papers comprise a peer-reviewed selection of presentations by authors from NASA, the Lunar and Planetary Institute (LPI), industry, and academia at the Second Conference on Lunar Bases and Space Activities of the 21st Century. These papers go into more technical depth than did those published from the first NASA-sponsored symposium on the topic, held in 1984. Session topics included the following: (1) design and operation of transportation systems to, in orbit around, and on the Moon; (2) lunar base site selection; (3) design, architecture, construction, and operation of lunar bases and human habitats; (4) lunar-based scientific research and experimentation in astronomy, exobiology, and lunar geology; (5) recovery and use of lunar resources; (6) environmental and human factors of and life support technology for human presence on the Moon; and (7) program management of human exploration of the Moon and space

    Brief report: Characteristics of antidepressant use in patients with heart failure

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    Paul J Mills1, Joel E Dimsdale1, Suzi Hong1, Geoffrey Van Den Brande2, Laura Redwine2, Barry H Greenberg2, Thomas Rutledge11Department of Psychiatry; 2Department of Medicine, University of California San Diego, La Jolla, CA, USABackground: Depression is common in heart failure (HF), but there is little data on the characteristics of antidepressant use in patients with HF.Objective: To survey basic information on antidepressant prescription characteristics, use, effectiveness, and follow-up.Methods: Observational study in two outpatient cardiology clinics of 37 NYHA class I&amp;ndash;IV HF patients taking antidepressant medication.Results: Thirty-one percent of prescriptions for antidepressants were obtained from psychiatrists, 58% from primary care physicians, and 8% from cardiologists. The majority of patients (87%) reported regularly taking their antidepressant medication as prescribed, however 48% reported never having had the dosage of their antidepressant medication adjusted. Only 53% of the patients reported that the medication had helped their mood &amp;ldquo;almost entirely&amp;rdquo; or &amp;ldquo;mostly&amp;rdquo; back to normal since starting their antidepressants, while the remaining patients reported that their mood was only &amp;ldquo;halfway&amp;rdquo; or &amp;ldquo;somewhat&amp;rdquo; back to normal or that the medication had not helped their depression at all. Among a subset of 10 patients who completed the Beck Depression (BDI) inventory, 6 still had depressed mood (BDI&amp;nbsp;&amp;ge; 10).Conclusion: The findings from this survey study provide insight into the characteristics of antidepressant use in patients with HF and argue for better follow up of HF patients who are prescribed antidepressants.Keywords: heart failure, antidepressant medication, adherence, effectivenes

    Comparative effectiveness of abatacept versus tocilizumab in rheumatoid arthritis patients with prior TNFi exposure in the US Corrona registry

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    BACKGROUND: We compared the effectiveness of abatacept (ABA) vs tocilizumab (TCA) in tumor necrosis factor inhibitor (TNFi) experienced patients. METHODS: We identified rheumatoid arthritis (RA) patients from a large observational US cohort (1 January 2010-31 May 2014) who had discontinued at least one TNFi and initiated ABA or TCZ in moderate or high disease activity based on the Clinical Disease Activity Index (CDAI) and had no prior exposure to the comparator drug. Using propensity score matching (1:1) stratified by prior TNF use (1 TNFi vs ≥2 TNFis), effectiveness at 6 months after initiation was evaluated. Mean change in CDAI over 6 months following initiation was the primary outcome, with secondary outcomes of achievement of low disease activity/remission (CDAI ≤ 10) and mean change in modified Health Assessment Questionnaire (mHAQ) score. RESULTS: The 264 pairs of propensity score-matched ABA and TCZ initiators were well matched with no substantial differences in the baseline characteristics, defined as standardized differences \u3e0.1 in the stratification. Both treatment groups had similar mean change in CDAI at 6 months (-11.3 in ABA vs -9.9 in TCZ; mean difference -1.27, 95% CI -3.65, 1.11). Similar proportions of both treatment groups achieved low disease activity/remission (adjusted odds ratio for ABA vs TCZ 0.99, 95% CI 0.69, 1.43). Mean change in mHAQ was -0.12 in ABA initiators vs -0.11 in TCZ initiations (mean difference -0.01, 95% CI -0.09, 0.06). CONCLUSIONS: Patients receiving either ABA or TCZ had substantial improvement in clinical disease activity. In this propensity score-matched sample, similar outcomes were observed for both treatment cohorts

    The comparative effectiveness of abatacept versus anti-tumour necrosis factor switching for rheumatoid arthritis patients previously treated with an anti-tumour necrosis factor

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    OBJECTIVE: We compared the effectiveness of abatacept (ABA) versus a subsequent anti-tumour necrosis factor inhibitor (anti-TNF) in rheumatoid arthritis (RA) patients with prior anti-TNF use. METHODS: We identified RA patients from a large observational US cohort (2/1/2000-8/7/2011) who had discontinued at least one anti-TNF and initiated either ABA or a subsequent anti-TNF. Using propensity score (PS) matching (n:1 match), effectiveness was measured at 6 and 12 months after initiation based on mean change in Clinical Disease Activity Index (CDAI), modified American College of Rheumatology (mACR) 20, 50 and 70 responses, modified Health Assessment Questionnaire (mHAQ) and CDAI remission in adjusted regression models. RESULTS: The PS-matched groups included 431 ABA and 746 anti-TNF users at 6 months and 311 ABA and 493 anti-TNF users at 12 months. In adjusted analyses comparing response following treatment with ABA and anti-TNF, the difference in weighted mean change in CDAI (range 6-8) at 6 months (0.46, 95% CI -0.82 to 1.73) and 12 months was similar (-1.64, 95% CI -3.47 to 0.19). The mACR20 responses were similar at 6 (28-32%, p=0.73) and 12 months (35-37%, p=0.48) as were the mACR50 and mACR70 (12 months: 20-22%, p=0.25 and 10-12%, p=0.49, respectively). Meaningful change in mHAQ was similar at 6 and 12 months (30-33%, p=0.41 and 29-30%, p=0.39, respectively) as was CDAI remission rates (9-10%, p=0.42 and 12-13%, p=0.91, respectively). CONCLUSIONS: RA patients with prior anti-TNF exposures had similar outcomes if they switched to a new anti-TNF as compared with initiation of ABA

    Immunosuppressive treatment and the risk of diabetes in rheumatoid arthritis

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    OBJECTIVE: Inflammation and anti-inflammatory treatments might influence the risk of diabetes. The objective of this study was to assess factors associated with incident diabetes in rheumatoid arthritis (RA). METHODS: The study population consisted of RA patients from a multi-center cohort study, Corrona. To assess risk associated with disease modifying antirheumatic drug (DMARD) exposure, we assessed five mutually exclusive DMARD groups. Additionally, we assessed the risk associated with body mass index (BMI, \u3c 25, 25-30, \u3e 30 kg/m2) and glucocorticoid usage. Incident cases of diabetes were confirmed through adjudication, and Cox regression models were fit to estimate the risk of incident diabetes. RESULTS: We identified 21,775 DMARD treatment regimens, the mean (SD) age at the index visit was 58 (13) years, disease duration 10 (10) years, and 30% used oral glucocorticoids at the time. Eighty-four incident cases of diabetes were confirmed within the treatment exposure periods. The hazard ratio (HR, 95% confidence interval) for diabetes was significantly reduced in patients receiving TNF inhibitors, HR 0.35 (0.13, 0.91), compared to patients treated with non-biologic DMARDs other than hydroxychloroquine and methotrexate. Hydroxychloroquine, methotrexate and use of other biologic DMARDs had a numerically reduced risk compared to the same group. Patients prescribed \u3e /=7.5 mg of glucocorticoids had a HR of 2.33 (1.68, 3.22) of incident diabetes compared with patients not prescribed oral glucocorticoids. RA patients with a BMI \u3e 30 had a HR of 6.27 (2.97, 13.25) compared to patients with BMI \u3c /=25. CONCLUSION: DMARDs, glucocorticoids and obesity influenced the risk of incident diabetes in a large cohort of RA patients. Monitoring for the occurrence of diabetes should be part of routine RA management with a focus on specific subgroups
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