3,736 research outputs found
Wanted: specific nutritional biomarkers for food consumption for the study of its protective role in health.
Nutritional epidemiology focuses on an understanding of the relationship between diet and disease risk. The assessment of dietary and nutritional exposure is a complex methodological challenge. Traditionally, diet evaluations have been made by means of dietary data, such as 24-h recalls and food frequency or diet history questionnaires. However, all of these methods have some inherent weaknesses or limitations due to the limited accuracy in measuring the intake of food, nutrients or phytochemicals. Nowadays, nutritional biomarkers have become an attractive alternative approach. According to conventional definition..
Polymeric Squaraine Dyes as Electron Donors in Bulk Heterojunction Solar Cells
A polysquaraine low band gap polymer was synthesized by Yamamoto coupling of
a monomeric dibromo indolenine squaraine dye. The resulting polymer has a
weight average molar mass in the order of Mw ~30.000-50.000 and a
polydispersity of ca. 1.7 as determined by gel-permeation chromatography (GPC).
The electronic properties of monomer and polymer were investigated by cyclic
voltammetry, absorption and emission spectroscopy. Owing to exciton coupling
the absorption bands of the polymer are red-shifted and strongly broadened
compared to the monomer squaraine dye. Bulk heterojunction solar cells were
prepared from blends of the polysquaraine with the fullerene derivative
[6,6]-phenyl C61-butyric acid methyl ester (PCBM) in different weight ratios
(1:3 to 1:1). The power conversion efficiencies under simulated AM 1.5
conditions yielded 0.45 % for these non-optimized systems. The external quantum
efficiency (EQE) shows that the photoresponse spans the range from 300 to 850
nm, which illustrates the promising properties of this novel organic
semiconductor as a low band gap donor material in organic photovoltaics.Comment: 10 pages, 7 figure
Precise absolute astrometry from the VLBA imaging and polarimetry survey at 5 GHz
We present in this paper accurate positions of 857 sources derived from the
astrometric analysis of 16 eleven-hour experiments from the Very Long Baseline
Array imaging and polarimetry survey at 5 GHz (VIPS). Among observed sources,
positions of 430 objects were not determined before at a milliarcsecond level
of accuracy. For 95% of the sources the uncertainty of their positions range
from 0.3 to 0.9 mas, with the median value of 0.5 mas. This estimate of
accuracy is substantiated by the comparison of positions of 386 sources that
were previously observed in astrometric programs simultaneously at 2.3/8.6 GHz.
Surprisingly, the ionosphere contribution to group delay was adequately modeled
with the use of the total electron contents maps derived from GPS observations
and only marginally affected estimates of source coordinates.Comment: Accepted for publication by the Astronomical Journal. 7 pages, 2
tables, 4 figures. Submission contains an ascii file with the catalogue. You
can get the catalogue by downloading the source of this paper and extracting
file table2.tx
Colorimetric detection of caspase 3 activity and reactive oxygen derivatives: Potential early indicators of thermal stress in corals
© 2016 Mickael Ros et al. There is an urgent need to develop and implement rapid assessments of coral health to allow effective adaptive management in response to coastal development and global change. There is now increasing evidence that activation of caspase-dependent apoptosis plays a key role during coral bleaching and subsequent mortality. In this study, a "clinical" approach was used to assess coral health by measuring the activity of caspase 3 using a commercial kit. This method was first applied while inducing thermal bleaching in two coral species, Acropora millepora and Pocillopora damicornis. The latter species was then chosen to undergo further studies combining the detection of oxidative stress-related compounds (catalase activity and glutathione concentrations) as well as caspase activity during both stress and recovery phases. Zooxanthellae photosystem II (PSII) efficiency and cell density were measured in parallel to assess symbiont health. Our results demonstrate that the increased caspase 3 activity in the coral host could be detected before observing any significant decrease in the photochemical efficiency of PSII in the algal symbionts and/or their expulsion from the host. This study highlights the potential of host caspase 3 and reactive oxygen species scavenging activities as early indicators of stress in individual coral colonies
Resveratrol metabolite profiling in clinical nutrition research-from diet to uncovering disease risk biomarkers: epidemiological evidence
Resveratrol is a bioactive plant compound that has drawn scientific and media attention owing to its protective effects against a wide variety of illnesses, including cardiovascular diseases and cancer. In the last two decades, a plethora of preclinical studies have shown these beneficial effects, and some of them have been supported by clinical trials. However, there are few epidemiological studies assessing these relationships, showing mostly inconsistent results among them. This could be partially due to the difficulty of accurately estimating dietary resveratrol exposure. The development of Phenol-Explorer, a database containing resveratrol food-composition data, will facilitate the estimation of resveratrol intake. Moreover, the discovery and validation of a nutritional biomarker of this exposure, urinary resveratrol metabolite profile, will allow a more accurate assessment of dietary resveratrol exposure. Few epidemiological studies have assessed the potential health effects of resveratrol. Resveratrol was not associated with total mortality, cancer, or cardiovascular events, but it was associated with an improvement of serum glucose and triglyceride levels and a decrease in heart rate. Together, these findings suggest a potential cardioprotective effect of resveratrol in epidemiological studies, although the evidence is still scarce
Resveratrol, a new biomarker of moderate wine intake?
In a recent study published in the British Journal of Nutrition, Spencer et al. (1) reviewed the strengths and the limitations of the biomarkers of dietary polyphenol intake, since nutritional biomarkers may be a better measure of dietary exposure than self-reported dietary data. These authors identified the criteria that must be considered in the development of such biomarkers as the following..
GeNN: a code generation framework for accelerated brain simulations
Large-scale numerical simulations of detailed brain circuit models are important for identifying hypotheses on brain functions and testing their consistency and plausibility. An ongoing challenge for simulating realistic models is, however, computational speed. In this paper, we present the GeNN (GPU-enhanced Neuronal Networks) framework, which aims to facilitate the use of graphics accelerators for computational models of large-scale neuronal networks to address this challenge. GeNN is an open source library that generates code to accelerate the execution of network simulations on NVIDIA GPUs, through a flexible and extensible interface, which does not require in-depth technical knowledge from the users. We present performance benchmarks showing that 200-fold speedup compared to a single core of a CPU can be achieved for a network of one million conductance based Hodgkin-Huxley neurons but that for other models the speedup can differ.
GeNN is available for Linux, Mac OS X and Windows platforms. The source code, user manual, tutorials,
Wiki, in-depth example projects and all other related information can be found on the project website http://genn-team.github.io/genn/
Radio Astrometry Of The Triple Systems Algol And UX Arietis
We have used multi-epoch long-baseline radio interferometry to determine the
proper motion and orbital elements of Algol and UX Arietis, two radio-bright,
close binary stellar systems with distant tertiary components. For Algol, we
refine the proper motion and outer orbit solutions, confirming the recent
result of Zavala et al. (2010) that the inner orbit is retrograde. The radio
centroid closely tracks the motion of the KIV secondary. In addition, the radio
morphology varies from double-lobed at low flux level to crescent-shaped during
active periods. These results are most easily interpreted as synchrotron
emission from a large, co-rotating meridional loop centered on the K-star. If
this is correct, it provides a radio-optical frame tie candidate with an
uncertainty {\pm}0.5 mas. For UX Arietis, we find a outer orbit solution that
accounts for previous VLBI observations of an acceleration term in the proper
motion fit. The outer orbit solution is also consistent with previously
published radial velocity curves and speckle observations of a third body. The
derived tertiary mass, 0.75 solar masses, is consistent with the K1
main-sequence star detected spectroscopically. The inner orbit solution favors
radio emission from the active K0IV primary only. The radio morphology,
consisting of a single, partially resolved emission region, may be associated
with the persistent polar spot observed using Doppler imaging
Low levels of a urinary biomarker of dietary polyphenol are associated with substantial cognition decline over a three-year period in older adults: the Invecchiare in Chianti (InCHIANTI) Study.
Objectives: To investigate the association of total urinary polyphenols (TUP) and total dietary polyphenols (TDP) with cognitive decline in an older population. Design: The Invecchiare in Chianti (InCHIANTI) study, a cohort study with a 3-year of follow-up. Setting: tuscany, italy. Participants: Non-demented adults aged 65 and older (N=652). Measurements: TUP and TDP concentrations were analysed at baseline using the Folin-Ciocalteu assay and a validated food frequency questionnaire, respectively. Cognition was assessed using the Mini-Mental State Examination (MMSE) and Trail Making Test (TMT) at baseline and after three years of follow-up. A substantial cognitive decline was defined as a reduction in the MMSE score of 3 or more points and as an increase of at least 29 seconds on the TMT A and 68 seconds on the TMT B (these thresholds represent the worst 10% of the distribution of decline) or as test discontinued due to multiple mistakes in TMT A and B at follow-up. Results: Higher TUP levels were associated with lower risk of substantial cognitive decline on the MMSE (odds ratio [OR] comparing extreme tertiles = 0.53; 95% confidence interval [CI] = 0.340.85; P-trend = 0.008) and on the TMT-A (OR = 0.52; 95 % CI = 0.280.96; P-trend = 0.03), but not on TMT-B in a logistic regression model that adjusted for baseline cognitive score and potential confounding factors. TDP did not affect the developing substantial cognitive decline in both tests. Conclusion: High concentrations of polyphenols, a nutritional biomarker of polyphenol intake, were associated with a lower risk of substantial cognitive decline in the older population studied over a three-year period, suggesting a protective effect against cognitive impairment
Síndrome de ardor bucal: actualización diagnóstica y terapéutica
El síndrome de boca ardiente (SBA) es una entidad patológica caracterizada por la presencia de síntomas crónicos de ardor o dolor en la mucosa bucal clínicamente normal. El SBA afecta principalmente a mujeres peri y posmenopáusicas. Su causa es desconocida, pero su relación con una compleja asociación de factores biológicos y psicológicos hace suponer una etiología multifactorial. Aunque se han encontrado tratamientos eficaces en casos particulares, se sigue buscando un tratamiento que resulte eficaz en la mayoría de los casos. Esta revisión hace especial referencia a los factores etiológicos y al tratamiento del síndrome
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