411 research outputs found
Methods to assess iron and iodine status
Four methods are recommended for assessment of iodine nutrition: urinary iodine concentration, the goitre rate, and blood concentrations of thyroid stimulating hormone and thyroglobulin. These indicators are complementary, in that urinary iodine is a sensitive indicator of recent iodine intake (days) and thyroglobulin shows an intermediate response (weeks to months), whereas changes in the goitre rate reflect long-term iodine nutrition (months to years). Spot urinary iodine concentrations are highly variable from day-to-day and should not be used to classify iodine status of individuals. International reference criteria for thyroid volume in children have recently been published and can be used for identifying even small goitres using thyroid ultrasound. Recent development of a dried blood spot thyroglobulin assay makes sample collection practical even in remote areas. Thyroid stimulating hormone is a useful indicator of iodine nutrition in the newborn, but not in other age groups. For assessing iron status, haemoglobin measurement alone has low specificity and sensitivity. Serum ferritin remains the best indicator of iron stores in the absence of inflammation. Measures of iron-deficient erythropoiesis include transferrin iron saturation and erythrocyte zinc protoporphyrin, but these often do not distinguish anaemia due to iron deficiency from the anaemia of chronic disease. The serum transferrin receptor is useful in this setting, but the assay requires standardization. In the absence of inflammation, a sensitive method to assess iron status is to combine the use of serum ferritin as a measure of iron stores and the serum transferrin receptor as a measure of tissue iron deficiency
Progress towards eliminating iodine deficiency in South Africa
Before the introduction of salt iodisation in 1954, South Africa was one of the many countries of the world with a lack of iodine in most of its territory and hence there was a need for a salt iodisation programme. The understanding of the iodine situation in South Africa, the basics of iodine nutrition and progress toward eliminating iodine deficiency internationally and in South Africa are reviewed in this paper. Voluntary salt iodisation in the country at 10¿20 ppm introduced in 1954 failed to eliminate endemic goitre and iodine deficiency. In contrast, considerable progress has been achieved in South Africa in eliminating iodine deficiency by introducing mandatory iodisation of table salt at 40¿60 ppm in 1995. A 1998 survey showed that optimal iodine nutrition was achieved nationally and in seven of the nine provinces, with more than adequate iodine intake in two provinces. At that time, 86.4% of households used iodised salt and 62.4% used adequately iodised salt that contained more than 15 ppm of iodine, with low coverage rates
Iron deficiency up-regulates iron absorption from ferrous sulphate but not ferric pyrophosphate and consequently food fortification with ferrous sulphate has relatively greater efficacy in iron-deficient individuals
Fe absorption from water-soluble forms of Fe is inversely proportional to Fe status in humans. Whether this is true for poorly soluble Fe compounds is uncertain. Our objectives were therefore (1) to compare the up-regulation of Fe absorption at low Fe status from ferrous sulphate (FS) and ferric pyrophosphate (FPP) and (2) to compare the efficacy of FS with FPP in a fortification trial to increase body Fe stores in Fe-deficient children v. Fe-sufficient children. Using stable isotopes in test meals in young women (n 49) selected for low and high Fe status, we compared the absorption of FPP with FS. We analysed data from previous efficacy trials in children (n 258) to determine whether Fe status at baseline predicted response to FS v. FPP as salt fortificants. Plasma ferritin was a strong negative predictor of Fe bioavailability from FS (P <0·0001) but not from FPP. In the efficacy trials, body Fe at baseline was a negative predictor of the change in body Fe for both FPP and FS, but the effect was significantly greater with FS (P <0·01). Because Fe deficiency up-regulates Fe absorption from FS but not from FPP, food fortification with FS may have relatively greater impact in Fe-deficient children. Thus, more soluble Fe compounds not only demonstrate better overall absorption and can be used at lower fortification levels, but they also have the added advantage that, because their absorption is up-regulated in Fe deficiency, they innately ‘target’ Fe-deficient individuals in a populatio
Schoolchildren in the Principality of Liechtenstein are mildly iodine deficient
Objective: To investigate the iodine status of schoolchildren in the Principality of Liechtenstein. Design: A representative, cross-sectional principality-wide screening of iodine level in household salt and urinary iodine concentrations (UIC) in primary-school children. Data were compared with the WHO criteria and with 2009 iodine survey data from Switzerland, a neighbouring country that supplies most of the salt used in Liechtenstein. Settings: Principality of Liechtenstein. Subjects: Schoolchildren (n 228) aged 6-12 years from five different primary schools representing 11.4% of the children at this age. Results: The median UIC was 96 (range: 10-446) mu g/l; 11 %, 56% and 1% of children had a UIC 300 mu g/l, respectively. In all, 79% of households were using adequately iodised salt (>= 15 ppm). The median UIC was 20% lower than that in children at comparable age in Switzerland (120 mu g/l; P <0.05). Conclusions: According to the WHO criteria, schoolchildren in Liechtenstein are mildly iodine deficient and household iodised salt coverage is inadequate. Public health measures to increase iodine intakes in the Principality should be considered
Resonant x-ray diffraction study of the magnetoresistant perovskite Pr0.6Ca0.4MnO3
We report a x-ray resonant diffraction study of the perovskite
Pr0.6Ca0.4MnO3. At the Mn K-edge, this technique is sensitive to details of the
electronic structure of the Mn atoms. We discuss the resonant x-ray spectra
measured above and below the charge and orbital ordering phase transition
temperature (TCOO = 232 K), and present a detailed analysis of the energy and
polarization dependence of the resonant scattering. The analysis confirms that
the structural transition is a transition to an orbitally ordered phase in
which inequivalent Mn atoms are ordered in a CE-type pattern. The Mn atoms
differ mostly by their 3d orbital occupation. We find that the charge
disproportionation is incomplete, 3d^{3.5-\delta} and 3d^{3.5+\delta} with
\delta\ll0.5 . A revised CE-type model is considered in which there are two Mn
sublattices, each with partial e_{g} occupancy. One sublattice consists of Mn
atoms with the 3x^{2}-r^{2} or 3y^{2}-r^{2} orbitals partially occupied, the
other sublattice with the x^{2}-y^{2} orbital partially occupied.Comment: 15 pages, 15 figure
Two-loop matching of the dipole operators for and
The order corrections to the Wilson coefficients of the dipole
operators () at the matching scale are a crucial ingredient
for a complete next- to-leading logarithmic calculation of the branching ratio
for . Given the phenomenological relevance and the fact that
this two-loop calculation has been done so far only by one group [1], we
present a detailed re-calculation using a different method. Our results are in
complete agreement with those in ref. [1].Comment: 24 pages, latex, 6 figures include
Finite SU(N)^k Unification
We consider N=1 supersymmetric gauge theories based on the group SU(N)_1 x
SU(N)_2 x ... x SU(N)_k with matter content (N,N*,1,...,1) + (1,N,N*,...,1) +
>... + (N*,1,1,...,N) as candidates for the unification symmetry of all
particles. In particular we examine to which extent such theories can become
finite and we find that a necessary condition is that there should be exactly
three families. We discuss further some phenomenological issues related to the
cases (N,k) = (3,3), (3,4), and (4,3), in an attempt to choose those theories
that can become also realistic. Thus we are naturally led to consider the
SU(3)^3 model which we first promote to an all-loop finite theory and then we
study its additional predictions concerning the top quark mass, Higgs mass and
supersymmetric spectrum.Comment: 15 page
Challenges in Complex Systems Science
FuturICT foundations are social science, complex systems science, and ICT.
The main concerns and challenges in the science of complex systems in the
context of FuturICT are laid out in this paper with special emphasis on the
Complex Systems route to Social Sciences. This include complex systems having:
many heterogeneous interacting parts; multiple scales; complicated transition
laws; unexpected or unpredicted emergence; sensitive dependence on initial
conditions; path-dependent dynamics; networked hierarchical connectivities;
interaction of autonomous agents; self-organisation; non-equilibrium dynamics;
combinatorial explosion; adaptivity to changing environments; co-evolving
subsystems; ill-defined boundaries; and multilevel dynamics. In this context,
science is seen as the process of abstracting the dynamics of systems from
data. This presents many challenges including: data gathering by large-scale
experiment, participatory sensing and social computation, managing huge
distributed dynamic and heterogeneous databases; moving from data to dynamical
models, going beyond correlations to cause-effect relationships, understanding
the relationship between simple and comprehensive models with appropriate
choices of variables, ensemble modeling and data assimilation, modeling systems
of systems of systems with many levels between micro and macro; and formulating
new approaches to prediction, forecasting, and risk, especially in systems that
can reflect on and change their behaviour in response to predictions, and
systems whose apparently predictable behaviour is disrupted by apparently
unpredictable rare or extreme events. These challenges are part of the FuturICT
agenda
A heat-stable microparticle platform for oral micronutrient delivery
Micronutrient deficiencies affect up to 2 billion people and are the leading cause of cognitive and physical disorders in the developing world. Food fortification is effective in treating micronutrient deficiencies; however, its global implementation has been limited by technical challenges in maintaining micronutrient stability during cooking and storage. We hypothesized that polymer-based encapsulation could address this and facilitate micronutrient absorption. We identified poly(butylmethacrylate-co-(2-dimethylaminoethyl)methacrylate-co-methylmethacrylate) (1:2:1) (BMC) as a material with proven safety, offering stability in boiling water, rapid dissolution in gastric acid, and the ability to encapsulate distinct micronutrients. We encapsulated 11 micronutrients (iron; iodine; zinc; and vitamins A, B2, niacin, biotin, folic acid, B12, C, and D) and co-encapsulated up to 4 micronutrients. Encapsulation improved micronutrient stability against heat, light, moisture, and oxidation. Rodent studies confirmed rapid micronutrient release in the stomach and intestinal absorption. Bioavailability of iron from microparticles, compared to free iron, was lower in an initial human study. An organotypic human intestinal model revealed that increased iron loading and decreased polymer content would improve absorption. Using process development approaches capable of kilogram-scale synthesis, we increased iron loading more than 30-fold. Scaled batches tested in a follow-up human study exhibited up to 89% relative iron bioavailability compared to free iron. Collectively, these studies describe a broad approach for clinical translation of a heat-stable ingestible micronutrient delivery platform with the potential to improve micronutrient deficiency in the developing world. These approaches could potentially be applied toward clinical translation of other materials, such as natural polymers, for encapsulation and oral delivery of micronutrients
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