325 research outputs found
The structural properties and star formation history of Leo T from deep LBT photometry
We present deep, wide-field g and r photometry of the transition type dwarf
galaxy Leo T, obtained with the blue arm of the Large Binocular Telescope. The
data confirm the presence of both very young (5
Gyr) stars. We study the structural properties of the old and young stellar
populations by preferentially selecting either population based on their color
and magnitude. The young population is significantly more concentrated than the
old population, with half-light radii of 104+-8 and 148+-16 pc respectively,
and their centers are slightly offset. Approximately 10% of the total stellar
mass is estimated to be represented by the young stellar population. Comparison
of the color-magnitude diagram (CMD) with theoretical isochrones as well as
numerical CMD-fitting suggest that star formation began over 10 Gyr ago and
continued in recent times until at least a few hundred Myr ago. The CMD-fitting
results are indicative of two distinct star formation bursts, with a quiescent
period around 3 Gyr ago, albeit at low significance. The results are consistent
with no metallicity evolution and [Fe/H] ~ -1.5 over the entire age of the
system. Finally, the data show little if any sign of tidal distortion of Leo T.Comment: 8 pages, 9 figures, some small textual changes, accepted for
publication in the Astrophysical Journa
Implantable loop recorder versus conventional diagnostic workup for unexplained recurrent syncope
Background
The most recent syncope guideline recommends that implantable loop recorders (ILRs) are implanted in the early phase of evaluation of people with recurrent syncope of uncertain origin in the absence of high-risk criteria, and in high-risk patients after a negative evaluation. Observational and case-control studies have shown that loop recorders lead to earlier diagnosis and reduce the rate of unexplained syncopes, justifying their use in clinical practice. However, only randomised clinical trials with an emphasis on a primary outcome of specific ILR-guided diagnosis and therapy, rather than simply electrocardiogram (ECG) diagnosis, might change clinical practice.
Objectives
To assess the incidence of mortality, quality of life, adverse events and costs of ILRs versus conventional diagnostic workup in people with unexplained syncope.
Search methods
We searched the Cochrane Central Register of Controlled Trials (CENTRAL, Issue 3, 2015), MEDLINE, EMBASE, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) Search Portal in April 2015. No language restriction was applied.
Selection criteria
We included all randomised controlled trials of adult participants (i.e. >= 18 years old) with a diagnosis of unexplained syncope comparing ILR with standard diagnostic workup.
Data collection and analysis
Two independent review authors screened titles and abstracts of all potential studies we identified as a result of the literature search, extracted study characteristics and outcome data from included studies and assessed risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions. We contacted authors of trials for missing data. We analysed dichotomous data (all-cause mortality and aetiologic diagnosis) as risk ratios (RR) with 95% confidence intervals (CI). We used the Chi(2) test to assess statistical heterogeneity (with P < 0.1) and the I-2 statistic to measure heterogeneity among the trials. We created a 'Summary of findings' table using the five GRADE considerations (study limitations, consistency of effect, imprecision, indirectness and publication bias) to assess the quality of a body of evidence as it relates to the studies which contribute data to the meta-analyses for the prespecified outcomes.
Main results
We included four trials involving a total of 579 participants. With the limitation that only two studies reported data on mortality and none of them had considered death as a primary endpoint, the meta-analysis showed no evidence of a difference in the risk of long-term mortality between participants who received ILR and those who were managed conventionally at follow-up (RR 0.97, 95% CI 0.41 to 2.30; participants = 255; studies = 2; very low quality evidence) with no evidence of heterogeneity. No data on short term mortality were available. Two studies reported data on adverse events after ILR implant. Due to the lack of data on adverse events in one of the studies' arms, a formal meta-analysis was not performed for this outcome.
Data from two trials seemed to show no difference in quality of life, although this finding was not supported by a formal analysis due to the differences in both the scores used and the way the data were reported. Data from two studies seemed to show a trend towards a reduction in syncope relapses after diagnosis in participants implanted with ILR. Cost analyses from two studies showed higher overall mean costs in the ILR group, if the costs incurred by the ILR implant were counted. The mean cost per diagnosis and the mean cost per arrhythmic diagnosis were lower for participants randomised to ILR implant.
Participants who underwent ILR implantation experienced higher rates of diagnosis (RR (in favour of ILR) 0.61, 95% CI 0.54 to 0.68; participants = 579; studies = 4; moderate quality evidence), as compared to participants in the standard assessment group, with no evidence of heterogeneity.
Authors' conclusions
Our systematic review shows that there is no evidence that an ILR-based diagnostic strategy reduces long-term mortality as compared to a standard diagnostic assessment (very low quality evidence). No data were available for short-term all-cause mortality. Moderate quality evidence shows that an ILR-based diagnostic strategy increases the rate of aetiologic diagnosis as compared to a standard diagnostic pathway. No conclusive data were available on the other end-points analysed.
Further trials evaluating the effect of ILRs in the diagnostic strategy of people with recurrent unexplained syncope are warranted. Future research should focus on the assessment of the ability of ILRs to change clinically relevant outcomes, such as quality of life, syncope relapse and costs
Effects of clockwise and counterclockwise job shift work rotation on sleep and work-life balance on hospital nurses
Rotational shift work is associated with sleep disturbances, increased risk of cardiovascular and psychological disorders, and may negatively impact work\u2013life balance. The direction of shift rotation (Clockwise, CW or counterclockwise, CCW) and its role in these disorders are poorly understood. The aim of the study was to investigate the effect of the shift schedule direction on sleep quantity and quality, alertness and work performance, and on work\u2013life balance on hospital nurses. One-hundred female nurses, working a continuous rapid shift schedule in hospitals in the north of Italy, participated in this cross-sectional study. Fifty worked on CW rotation schedule (Morning: 6 a.m.\u20132 p.m., Afternoon: 2 p.m.\u201310 p.m., Night: 10 p.m.\u20136 a.m., 2 rest days) and fifty on CCW rotation (Afternoon, Morning, Morning, Night, 3 rest days). Data were collected by ad hoc questionnaire and daily diary. During the shift cycle CW nurses slept longer (7.40 \ub1 2.24 h) than CCW (6.09 \ub1 1.73; p < 0.001). CW nurses reported less frequently than CCW awakening during sleep (40% vs. 80%; p < 0.001), attention disturbance during work (20% vs. 64%; p < 0.001), and interference with social and family life (60% vs. 96% and 20% vs. 70%, respectively; p < 0.001). CCW rotating shift schedule seems to be characterized by higher sleep disturbances and a worse work\u2013life balance
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An Active Learning Approach for Rapid Characterization of Endothelial Cells in Human Tumors
Currently, no available pathological or molecular measures of tumor angiogenesis predict response to antiangiogenic therapies used in clinical practice. Recognizing that tumor endothelial cells (EC) and EC activation and survival signaling are the direct targets of these therapies, we sought to develop an automated platform for quantifying activity of critical signaling pathways and other biological events in EC of patient tumors by histopathology. Computer image analysis of EC in highly heterogeneous human tumors by a statistical classifier trained using examples selected by human experts performed poorly due to subjectivity and selection bias. We hypothesized that the analysis can be optimized by a more active process to aid experts in identifying informative training examples. To test this hypothesis, we incorporated a novel active learning (AL) algorithm into FARSIGHT image analysis software that aids the expert by seeking out informative examples for the operator to label. The resulting FARSIGHT-AL system identified EC with specificity and sensitivity consistently greater than 0.9 and outperformed traditional supervised classification algorithms. The system modeled individual operator preferences and generated reproducible results. Using the results of EC classification, we also quantified proliferation (Ki67) and activity in important signal transduction pathways (MAP kinase, STAT3) in immunostained human clear cell renal cell carcinoma and other tumors. FARSIGHT-AL enables characterization of EC in conventionally preserved human tumors in a more automated process suitable for testing and validating in clinical trials. The results of our study support a unique opportunity for quantifying angiogenesis in a manner that can now be tested for its ability to identify novel predictive and response biomarkers
Quality of Life During Treatment With Chemohormonal Therapy: Analysis of E3805 Chemohormonal Androgen Ablation Randomized Trial in Prostate Cancer
Purpose
Chemohormonal therapy with docetaxel and androgen deprivation therapy (ADT+D) for metastatic hormone-sensitive prostate cancer improves overall survival as compared with androgen deprivation therapy (ADT) alone. We compared the quality of life (QOL) between patients with metastatic hormone-sensitive prostate cancer who were treated with ADT+D and those who were treated with ADT alone.
Methods
Men were randomly assigned to ADT+ D (six cycles) or to ADT alone. QOL was assessed by Functional Assessment of Cancer Therapy-Prostate (FACT-P), FACT-Taxane, Functional Assessment of Chronic Illness Therapy-Fatigue, and the Brief Pain Inventory at baseline and at 3, 6, 9, and 12 months. The Wilcoxon signed rank test was used to examine changes over time. Mixed-effect models compared the QOL between arms at each time point.
Results
Seven hundred ninety men were randomly assigned (ADT+D [n = 397] and ADT[ n = 393]) and completed FACT-P (90% at baseline, 86% at 3 months, 83% at 6 months, 78% at 9 months, and 77% at 12 months). ADT+D patients reported a statistically significant decline in FACT-P at 3 months (P \u3c .001) but FACT-P did not differ significantly between baseline and 12 months (P = .38). ADT+D FACT-P scores were significantly lower at 3 months (P = .02) but significantly higher at 12 months (P = .04) when compared with ADT FACT-P scores. Differences did not exceed the minimal clinically important difference at any time point. ADT+D patients reported significantly lower Functional Assessment of Chronic Illness Therapy-Fatigue scores at 3 months than did ADT patients (P \u3c .001). Over time, both arms reported significantly poorer FACT-Taxane scores (P \u3c .001) when compared with baseline. Brief Pain Inventory scores were similar between arms.
Conclusion
Although ADT+D was associated with statistically worse QOL at 3 months, QOL was better at 12 months for ADT+D patients than for ADT patients. Both arms reported a similar minimally changed QOL over time, suggesting that ADT+D is not associated with a greater long-term negative impact on QOL
Can strenuous exercise harm the heart? Insights from a study of cardiovascular neural regulation in amateur triathletes
Regular exercise is recommended to improve the cardiovascular risk profile. However, there is growing evidence that extreme volumes and intensity of long-term exertion may increase the risk of acute cardiac events. The aim of this study is to investigate the aftereffects of regular, strenuous physical training on the cardiovascular neural regulation in a group of amateur triathletes compared to age-matched sedentary controls. We enrolled 11 non-elite triathletes (4 women, age 24 +/- 4 years), who had refrained from exercise for 72 hours, and 11 age-matched healthy non-athletes (3 women, age 25 +/- 2 years). Comprehensive echocardiographic and cardiopulmonary exercise tests were performed at baseline. Electrocardiogram, non-invasive blood pressure, respiratory activity, and muscle sympathetic nerve activity (MSNA) were continuously recorded in a supine position (REST) and during an incremental 15 degrees step-wise head-up tilt test up to 75 degrees (TILT). Blood samples were collected for determination of stress mediators. Autoregressive spectral analysis provided the indices of the cardiac sympathetic (LFRR) and vagal (HFRR) activity, the vascular sympathetic control (LFSAP), and the cardiac sympatho-vagal modulation (LF/HF). Compared to controls, triathletes were characterized by greater LFRR, LF/HF ratio, LFSAP, MSNA, and lower HFRR at REST and during TILT, i.e. greater overall cardiovascular sympathetic modulation together with lower cardiac vagal activity. Cortisol and adrenocorticotropic hormone concentrations were also higher in triathletes. In conclusion, triathletes were characterized by signs of sustained cardiovascular sympathetic overactivity. This might represent a risk factor for future cardiovascular events, given the known association between chronic excessive sympathetic activity and increased cardiovascular risk
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