1,285 research outputs found
Estimation of Dietary Iron Bioavailability from Food Iron Intake and Iron Status
Currently there are no satisfactory methods for estimating dietary iron absorption (bioavailability) at a population level, but this is essential for deriving dietary reference values using the factorial approach. The aim of this work was to develop a novel approach for estimating dietary iron absorption using a population sample from a sub-section of the UK National Diet and Nutrition Survey (NDNS). Data were analyzed in 873 subjects from the 2000–2001 adult cohort of the NDNS, for whom both dietary intake data and hematological measures (hemoglobin and serum ferritin (SF) concentrations) were available. There were 495 men aged 19–64 y (mean age 42.7±12.1 y) and 378 pre-menopausal women (mean age 35.7±8.2 y). Individual dietary iron requirements were estimated using the Institute of Medicine calculations. A full probability approach was then applied to estimate the prevalence of dietary intakes that were insufficient to meet the needs of the men and women separately, based on their estimated daily iron intake and a series of absorption values ranging from 1–40%. The prevalence of SF concentrations below selected cut-off values (indicating that absorption was not high enough to maintain iron stores) was derived from individual SF concentrations. An estimate of dietary iron absorption required to maintain specified SF values was then calculated by matching the observed prevalence of insufficiency with the prevalence predicted for the series of absorption estimates. Mean daily dietary iron intakes were 13.5 mg for men and 9.8 mg for women. Mean calculated dietary absorption was 8% in men (50th percentile for SF 85 µg/L) and 17% in women (50th percentile for SF 38 µg/L). At a ferritin level of 45 µg/L estimated absorption was similar in men (14%) and women (13%). This new method can be used to calculate dietary iron absorption at a population level using data describing total iron intake and SF concentration
Zinc intake, status and indices of cognitive function in adults and children: a systematic review and meta-analysis
In developing countries, deficiencies of micronutrients are thought to have a major impact on child development; however, a consensus on the specific relationship between dietary zinc intake and cognitive function remains elusive. The aim of this systematic review was to examine the relationship between zinc intake, status and indices of cognitive function in children and adults. A systematic literature search was conducted using EMBASE, MEDLINE and Cochrane Library databases from inception to March 2014. Included studies were those that supplied zinc as supplements or measured dietary zinc intake. A meta-analysis of the extracted data was performed where sufficient data were available. Of all of the potentially relevant papers, 18 studies met the inclusion criteria, 12 of which were randomised controlled trials (RCTs; 11 in children and 1 in adults) and 6 were observational studies (2 in children and 4 in adults). Nine of the 18 studies reported a positive association between zinc intake or status with one or more measure of cognitive function. Meta-analysis of data from the adult’s studies was not possible because of limited number of studies. A meta-analysis of data from the six RCTs conducted in children revealed that there was no significant overall effect of zinc intake on any indices of cognitive function: intelligence, standard mean difference of <0.001 (95% confidence interval (CI) –0.12, 0.13) P=0.95; executive function, standard mean difference of 0.08 (95% CI, –0.06, 022) P=0.26; and motor skills standard mean difference of 0.11 (95% CI –0.17, 0.39) P=0.43. Heterogeneity in the study designs was a major limitation, hence only a small number (n=6) of studies could be included in the meta-analyses. Meta-analysis failed to show a significant effect of zinc supplementation on cognitive functioning in children though, taken as a whole, there were some small indicators of improvement on aspects of executive function and motor development following supplementation but high-quality RCTs are necessary to investigate this further
Active wetting of epithelial tissues
Development, regeneration and cancer involve drastic transitions in tissue
morphology. In analogy with the behavior of inert fluids, some of these
transitions have been interpreted as wetting transitions. The validity and
scope of this analogy are unclear, however, because the active cellular forces
that drive tissue wetting have been neither measured nor theoretically
accounted for. Here we show that the transition between 2D epithelial
monolayers and 3D spheroidal aggregates can be understood as an active wetting
transition whose physics differs fundamentally from that of passive wetting
phenomena. By combining an active polar fluid model with measurements of
physical forces as a function of tissue size, contractility, cell-cell and
cell-substrate adhesion, and substrate stiffness, we show that the wetting
transition results from the competition between traction forces and contractile
intercellular stresses. This competition defines a new intrinsic lengthscale
that gives rise to a critical size for the wetting transition in tissues, a
striking feature that has no counterpart in classical wetting. Finally, we show
that active shape fluctuations are dynamically amplified during tissue
dewetting. Overall, we conclude that tissue spreading constitutes a prominent
example of active wetting --- a novel physical scenario that may explain
morphological transitions during tissue morphogenesis and tumor progression
Regional Genetic Structure in the Aquatic Macrophyte Ruppia cirrhosa Suggests Dispersal by Waterbirds
The evolutionary history of the genus Ruppia has been shaped by hybridization, polyploidisation and vicariance that have resulted in a problematic taxonomy. Recent studies provided insight into species circumscription, organelle takeover by hybridization, and revealed the importance of verifying species identification to avoid distorting effects of mixing different species, when estimating population connectivity. In the present study, we use microsatellite markers to determine population diversity and connectivity patterns in Ruppia cirrhosa including two spatial scales: (1) from the Atlantic Iberian coastline in Portugal to the Siculo-Tunisian Strait in Sicily and (2) within the Iberian Peninsula comprising the Atlantic-Mediterranean transition. The higher diversity in the Mediterranean Sea suggests that populations have had longer persistence there, suggesting a possible origin and/or refugial area for the species. The high genotypic diversities highlight the importance of sexual reproduction for survival and maintenance of populations. Results revealed a regional population structure matching a continent-island model, with strong genetic isolation and low gene flow between populations. This population structure could be maintained by waterbirds, acting as occasional dispersal vectors. This information elucidates ecological strategies of brackish plant species in coastal lagoons, suggesting mechanisms used by this species to colonize new isolated habitats and dominate brackish aquatic macrophyte systems, yet maintaining strong genetic structure suggestive of very low dispersal.Fundacao para a Cincia e Tecnologia (FCT, Portugal) [PTDC/MAR/119363/2010, BIODIVERSA/0004/2015, UID/Multi/04326/2013]Pew FoundationSENECA FoundationMurcia Government, Spain [11881/PI/09]FCT Investigator Programme-Career Development [IF/00998/2014]Spanish Ministry of Education [AP2008-01209]European Community [00399/2012]info:eu-repo/semantics/publishedVersio
Viroids: survivors from the RNA world?
[EN] Because RNA can be a carrier of genetic information and a biocatalyst, there
is a consensus that it emerged before DNA and proteins, which eventually
assumed these roles and relegated RNA to intermediate functions. If such a
scenario¿the so-calledRNAworld¿existed,wemight hope to find its relics
in our presentworld. The properties of viroids that make them candidates for
being survivors of the RNA world include those expected for primitive RNA
replicons: (a) small size imposed by error-prone replication, (b) high G +
C content to increase replication fidelity, (c) circular structure for assuring
complete replication without genomic tags, (d ) structural periodicity for
modular assembly into enlarged genomes, (e) lack of protein-coding ability
consistent with a ribosome-free habitat, and ( f ) replication mediated in some
by ribozymes, the fingerprint of the RNA world. With the advent of DNA
and proteins, those protoviroids lost some abilities and became the plant
parasites we now know.R.F. has received funding by grant BFU2011-28443 from Ministerio de Economia y Competititvidad (MINECO, Spain), R.S. by grants BFU2011-25271 (MINECO) and ERC-2011-StG-281191-VIRMUT (European Research Council), and S.F.E. by grant BFU2012-30805 (MINECO). P.S. has been supported by postdoctoral contracts from Generalitat Valenciana (APOSTD/2010, program VALi+d) and MINECO (program Juan de la Cierva).Flores Pedauye, R.; Gago Zachert, SP.; Serra Alfonso, P.; Sanjuan Verdeguer, R.; Elena Fito, SF. (2014). Viroids: survivors from the RNA world?. Annual Review of Microbiology. 68:395-414. https://doi.org/10.1146/annurev-micro-091313-103416S3954146
A combined analysis technique for the search for fast magnetic monopoles with the MACRO detector
We describe a search method for fast moving ()
magnetic monopoles using simultaneously the scintillator, streamer tube and
track-etch subdetectors of the MACRO apparatus. The first two subdetectors are
used primarily for the identification of candidates while the track-etch one is
used as the final tool for their rejection or confirmation. Using this
technique, a first sample of more than two years of data has been analyzed
without any evidence of a magnetic monopole. We set a 90% CL upper limit to the
local monopole flux of in the
velocity range and for nucleon decay
catalysis cross section smaller than .Comment: 29 pages (12 figures). Accepted by Astroparticle Physic
Final results of magnetic monopole searches with the MACRO experiment
We present the final results obtained by the MACRO experiment in the search
for GUT magnetic monopoles in the penetrating cosmic radiation, for the range
. Several searches with all the MACRO sub-detectors
(i.e. scintillation counters, limited streamer tubes and nuclear track
detectors) were performed, both in stand alone and combined ways. No candidates
were detected and a 90% Confidence Level (C.L.) upper limit to the local
magnetic monopole flux was set at the level of cm
s sr. This result is the first experimental limit obtained in
direct searches which is well below the Parker bound in the whole range
in which GUT magnetic monopoles are expected.Comment: 12 pages, Latex, 9 figures and 2 Table
The Observation of Up-going Charged Particles Produced by High Energy Muons in Underground Detectors
An experimental study of the production of up-going charged particles in
inelastic interactions of down-going underground muons is reported, using data
obtained from the MACRO detector at the Gran Sasso Laboratory. In a sample of
12.2 10^6 single muons, corresponding to a detector livetime of 1.55 y, 243
events are observed having an up-going particle associated with a down-going
muon. These events are analysed to determine the range and emission angle
distributions of the up-going particle, corrected for detection and
reconstruction efficiency. Measurements of the muon neutrino flux by
underground detectors are often based on the observation of through-going and
stopping muons produced in interactions in the rock below the
detector. Up-going particles produced by an undetected down-going muon are a
potential background source in these measurements. The implications of this
background for neutrino studies using MACRO are discussed.Comment: 18 pages, 9 figures. Accepted by Astrop. Physic
Nuclearite search with the MACRO detector at Gran Sasso
In this paper we present the results of a search for nuclearites in the
penetrating cosmic radiation using the scintillator and track-etch subdetectors
of the MACRO apparatus. The analyses cover the beta =v/c range at the detector
depth (3700 hg/cm^2) 10^-5 < beta < 1; for beta = 2 x 10^-3 the flux limit is
2.7 x 10^-16 cm^-2 s^-1 sr^-1 for an isotropic flux of nuclearites, and twice
this value for a flux of downgoing nuclearites.Comment: 16 pages, 4 Encapsulated Postscript figures, uses article.sty.
Submitted to The European Physical Journal
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