2,075 research outputs found
High-intensity compared to moderate-intensity training for exercise initiation, enjoyment, adherence, and intentions: an intervention study
Background:
Understanding exercise participation for overweight and obese adults is critical for preventing comorbid conditions. Group-based high-intensity functional training (HIFT) provides time-efficient aerobic and resistance exercise at self-selected intensity levels which can increase adherence; behavioral responses to HIFT are unknown. This study examined effects of HIFT as compared to moderate-intensity aerobic and resistance training (ART) on exercise initiation, enjoyment, adherence, and intentions.
Methods:
A stratified, randomized two-group pre-test posttest intervention was conducted for eight weeks in 2012 with analysis in 2013. Participants (n = 23) were stratified by median age (< or ≥ 28) and body mass index (BMI; < or ≥ 30.5). Participants were physically inactive with an average BMI of 31.1 ± 3.5 kg/m2, body fat percentage of 42.0 ± 7.4%, weight of 89.5 ± 14.2 kg, and ages 26.8 ± 5.9 years. Most participants were white, college educated, female, and married/engaged. Both groups completed 3 training sessions per week. The ART group completed 50 minutes of moderate aerobic exercise each session and full-body resistance training on two sessions per week. The HIFT group completed 60-minute sessions of CrossFit™ with actual workouts ranging from 5–30 minutes. Participants completed baseline and posttest questionnaires indicating reasons for exercise initiation (baseline), exercise enjoyment, and exercise intentions (posttest). Adherence was defined as completing 90% of exercise sessions. Daily workout times were recorded.
Results:
Participants provided mostly intrinsic reasons for exercise initiation. Eighteen participants adhered (ART = 9, 81.8%; HIFT = 9, 75%). HIFT dropouts (p = .012) and ART participants (p = .009) reported lower baseline exercise enjoyment than HIFT participants, although ART participants improved enjoyment at posttest (p = .005). More HIFT participants planned to continue the same exercise than ART participants (p = .002). No significant changes in BMI or body composition were found. Workouts were shorter for HIFT than ART (p < .001).
Conclusions:
HIFT participants spent significantly less time exercising per week, yet were able to maintain exercise enjoyment and were more likely to intend to continue. High-intensity exercise options should be included in public health interventions
Breaking Cosmological Degeneracies in Galaxy Cluster Surveys with a Physical Model of Cluster Structure
Forthcoming large galaxy cluster surveys will yield tight constraints on
cosmological models. It has been shown that in an idealized survey, containing
> 10,000 clusters, statistical errors on dark energy and other cosmological
parameters will be at the percent level. It has also been shown that through
"self-calibration", parameters describing the mass-observable relation and
cosmology can be simultaneously determined, though at a loss in accuracy by
about an order of magnitude. Here we examine the utility of an alternative
approach of self-calibration, in which a parametrized ab-initio physical model
is used to compute cluster structure and the resulting mass-observable
relations. As an example, we use a modified-entropy ("pre-heating") model of
the intracluster medium, with the history and magnitude of entropy injection as
unknown input parameters. Using a Fisher matrix approach, we evaluate the
expected simultaneous statistical errors on cosmological and cluster model
parameters. We study two types of surveys, in which a comparable number of
clusters are identified either through their X-ray emission or through their
integrated Sunyaev-Zel'dovich (SZ) effect. We find that compared to a
phenomenological parametrization of the mass-observable relation, using our
physical model yields significantly tighter constraints in both surveys, and
offers substantially improved synergy when the two surveys are combined. These
results suggest that parametrized physical models of cluster structure will be
useful when extracting cosmological constraints from SZ and X-ray cluster
surveys. (abridged)Comment: 22 pages, 8 figures, accepted to Ap
Cosmological Simulations of the Preheating Scenario for Galaxy Cluster Formation: Comparison to Analytic Models and Observations
We perform a set of non--radiative cosmological simulations of a preheated
intracluster medium in which the entropy of the gas was uniformly boosted at
high redshift. The results of these simulations are used first to test the
current analytic techniques of preheating via entropy input in the smooth
accretion limit. When the unmodified profile is taken directly from
simulations, we find that this model is in excellent agreement with the results
of our simulations. This suggests that preheated efficiently smoothes the
accreted gas, and therefore a shift in the unmodified profile is a good
approximation even with a realistic accretion history. When we examine the
simulation results in detail, we do not find strong evidence for entropy
amplification, at least for the high-redshift preheating model adopted here. In
the second section of the paper, we compare the results of the preheating
simulations to recent observations. We show -- in agreement with previous work
-- that for a reasonable amount of preheating, a satisfactory match can be
found to the mass-temperature and luminosity-temperature relations. However --
as noted by previous authors -- we find that the entropy profiles of the
simulated groups are much too flat compared to observations. In particular,
while rich clusters converge on the adiabatic self--similar scaling at large
radius, no single value of the entropy input during preheating can
simultaneously reproduce both the core and outer entropy levels. As a result,
we confirm that the simple preheating scenario for galaxy cluster formation, in
which entropy is injected universally at high redshift, is inconsistent with
observations.Comment: 11 pages, 13 figures, accepted for publication in Ap
Comparison of Solar Electric and Chemical Propulsion Missions
Solar Electric Propulsion (SEP) offers fuel efficiency and mission robustness for spacecraft. The combination of solar power and electric propulsion engines is currently used for missions ranging from geostationary stationkeeping to deep space science because of these benefits. Both solar power and electric propulsion technologies have progressed to the point where higher electric power systems can be considered, making substantial cargo missions and potentially human missions viable. This paper evaluates and compares representative lunar, Mars, and Sun-Earth Langrangian point missions using SEP and chemical propulsion subsystems. The potential benefits and limitations are discussed along with technology gaps that need to be resolved for such missions to become possible. The connection to NASA's human architecture and technology development efforts will be discussed
Serotonin receptors and heart valve disease—It was meant 2B
Carcinoid heart disease was one of the first valvular pathologies studied in molecular detail, and early research identified serotonin produced by oncogenic enterochromaffin cells as the likely culprit in causing changes in heart valve tissue. Researchers and physicians in the mid-1960s noted a connection between the use of several ergot-derived medications with structures similar to serotonin and the development of heart valve pathologies similar to those observed in carcinoid patients. The exact serotonergic target that mediated valvular pathogenesis remained a mystery for many years until similar cases were reported in patients using the popular diet drug Fen-Phen in the late 1990s. The Fen-Phen episode sparked renewed interest in serotonin-mediated valve disease, and studies led to the identification of the 5-HT2B receptor as the likely molecular target leading to heart valve tissue fibrosis. Subsequent studies have identified numerous other activators of the 5-HT2B receptor, and consequently, the use of many of these molecules has been linked to heart valve disease. Herein, we: review the molecular properties of the 5-HT2B receptor including factors that differentiate the 5-HT2B receptor from other 5-HT receptor subtypes, discuss the studies that led to the identification of the 5-HT2B receptor as the mediator of heart valve disease, present current efforts to identify potential valvulopathogens by screening for 5-HT2B receptor activity, and speculate on potential therapeutic benefits of 5-HT2B receptor targeting
Environmental Perturbations that Cause Structural Changes in the SNARE Protein SNAP-25
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Long-Term Corticosteroid-Sparing Immunosuppression for Cardiac Sarcoidosis.
Background Long-term corticosteroid therapy is the standard of care for treatment of cardiac sarcoidosis (CS). The efficacy of long-term corticosteroid-sparing immunosuppression in CS is unknown. The goal of this study was to assess the efficacy of methotrexate with or without adalimumab for long-term disease suppression in CS, and to assess recurrence and adverse event rates after immunosuppression discontinuation. Methods and Results Retrospective chart review identified treatment-naive CS patients at a single academic medical center who received corticosteroid-sparing maintenance therapy. Demographics, cardiac uptake of 18-fluorodeoxyglucose, and adverse cardiac events were compared before and during treatment and between those with persistent or interrupted immunosuppression. Twenty-eight CS patients were followed for a mean 4.1 (SD 1.5) years. Twenty-five patients received 4 to 8 weeks of high-dose prednisone (>30 mg/day), followed by taper and maintenance therapy with methotrexate±low-dose prednisone (low-dose prednisone, <10 mg/day). Adalimumab was added in 19 patients with persistently active CS or in those with intolerance to methotrexate. Methotrexate±low-dose prednisone resulted in initial reduction (88%) or elimination (60%) of 18-fluorodeoxyglucose uptake, and patients receiving adalimumab-containing regimens experienced improved (84%) or resolved (63%) 18-fluorodeoxyglucose uptake. Radiologic relapse occurred in 8 of 9 patients after immunosuppression cessation, 4 patients on methotrexate-containing regimens, and in no patients on adalimumab-containing regimens. Conclusions Corticosteroid-sparing regimens containing methotrexate with or without adalimumab is an effective maintenance therapy in patients after an initial response is confirmed. Disease recurrence in patients on and off immunosuppression support need for ongoing radiologic surveillance regardless of immunosuppression regimen
The Radio Variability of the Gravitational Lens PMN J1838-3427
We present the results of a radio variability study of the gravitational lens
PMN J1838-3427. Our motivation was to determine the Hubble constant by
measuring the time delay between variations of the two quasar images. We
monitored the system for 4 months (approximately 5 times longer than the
expected delay) using the Australia Telescope Compact Array at 9 GHz. Although
both images were variable on a time scale of a few days, no correlated
intrinsic variability could be identified, and therefore no time delay could be
measured. Notably, the fractional variation of the fainter image (8%) was
greater than that of the brighter image (4%), whereas lensed images of a point
source would have the same fractional variation. This effect can be explained,
at least in part, as the refractive scintillation of both images due to the
turbulent interstellar medium of the Galaxy.Comment: To appear in AJ (8 pages, including 4 figures
Predictors of web-based follow-up response in the Prevention of Low Back Pain in the Military Trial (POLM)
<p>Abstract</p> <p>Background</p> <p>Achieving adequate follow-up in clinical trials is essential to establish the validity of the findings. Achieving adequate response rates reduces bias and increases probability that the findings can be generalized to the population of interest. Therefore, the purpose of this study was to determine the influence of attention, demographic, psychological, and health status factors on web-based response rates in the ongoing Prevention of Low Back Pain in the Military (POLM) trial.</p> <p>Methods</p> <p>Twenty companies of Soldiers (n = 4,325) were cluster randomized to complete a traditional exercise program including sit-ups (TEP) with or without a psychosocial educational program (PSEP) or a core stabilization exercise program (CSEP) with or without PSEP. A subgroup of Soldiers (n = 371) was randomized to receive an additional physical and ultrasound imaging (USI) examination of key trunk musculature. As part of the surveillance program, all Soldiers were encouraged to complete monthly surveys via email during the first year. Descriptive statistics of the predictor variables were obtained and compared between responders and non-responders using two sample t-tests or chi-square test, as appropriate. Generalized linear mixed models were subsequently fitted for the dichotomous outcomes to estimate the effects of the predictor variables. The significance level was set at .05 a priori.</p> <p>Results</p> <p>The overall response rate was 18.9% (811 subjects) for the first year. Responders were more likely to be older, Caucasian, have higher levels of education and income, reservist military status, non smoker, lower BMI, and have received individualized attention via the physical/USI examination (p < .05). Age, race/ethnicity, education, military status, smoking history, BMI, and whether a Soldier received the physical/USI examination remained statistically significant (p < .05) when considered in a full multivariate model.</p> <p>Conclusion</p> <p>The overall web based response rate during the first year of the POLM trial was consistent with studies that used similar methodology, but lower when compared to rates expected for standard clinical trials. One year response rate was significantly associated with demographic characteristics, health status, and individualized attention via additional testing. These data may assist for planning of future trials that use web based response systems.</p> <p>Trial Registration</p> <p>This study has been registered at reports at <url>http://clinicaltrials.gov</url> (<a href="http://www.clinicaltrials.gov/ct2/show/NCT00373009">NCT00373009</a>).</p
Probing the dynamics of O-GlcNAc glycosylation in the brain using quantitative proteomics
The addition of the monosaccharide beta-N-acetyl-D-glucosamine to proteins (O-GlcNAc glycosylation) is an intracellular, post-translational modification that shares features with phosphorylation. Understanding the cellular mechanisms and signaling pathways that regulate O-GlcNAc glycosylation has been challenging because of the difficulty of detecting and quantifying the modification. Here, we describe a new strategy for monitoring the dynamics of O-GlcNAc glycosylation using quantitative mass spectrometry-based proteomics. Our method, which we have termed quantitative isotopic and chemoenzymatic tagging (QUIC-Tag), combines selective, chemoenzymatic tagging of O-GlcNAc proteins with an efficient isotopic labeling strategy. Using the method, we detect changes in O-GlcNAc glycosylation on several proteins involved in the regulation of transcription and mRNA translocation. We also provide the first evidence that O-GlcNAc glycosylation is dynamically modulated by excitatory stimulation of the brain in vivo. Finally, we use electron-transfer dissociation mass spectrometry to identify exact sites of O-GlcNAc modification. Together, our studies suggest that O-GlcNAc glycosylation occurs reversibly in neurons and, akin to phosphorylation, may have important roles in mediating the communication between neurons
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