1,721,068 research outputs found
Calcium and Iron nutrition through the reproductive life course
No full textBackground: two essential micronutrients over the life course are calcium and iron, and both are especially important during the reproductive cycle. The role of calcium in maternal and offspring bone health and in the prevention of pre-eclampsia in pregnancy are well described, although results from randomised controlled trials for both outcomes vary. Iron is essential for synthesis of red blood cells, being a core component of haemoglobin, which carries oxygen around the body, and hence is key in the prevention of anaemia and sequelae.Summary: this article reviews the evidence across the reproductive life course for dietary calcium and iron intakes and health outcomes. For calcium, focusing on bone health and prevention of pre-eclampsia, for iron considering its crucial role in foetal and neonatal development and how requirements may be impacted through inflammation and infection, particularly in environments where iron availability may be low.</p
Long-term effects of maternal calcium supplementation on childhood growth differ between males and females in a population accustomed to a low calcium intake
No full textThe importance of adequate calcium intakes for healthy growth and bone development has long been recognised. Recent evidence suggests that calcium supplementation may have sex-specific effects on bone growth in childhood. The aim was to describe the long-term effects of calcium supplementation in pregnant Gambian women with a low calcium intake (ISCRTN96502494) on offspring height, weight, bone and body composition in childhood, and whether the effects differ by sex.
Children of mothers who participated in the original calcium supplementation trial were measured at age 8–12 years using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Linear models tested for sex*supplement interactions before and after adjusting for current age and size in early life.
447 children, aged 9.2(SD 0.9) years, were measured. Significant sex*supplement interactions (p < 0.05) were observed for many of the anthropometric and bone outcomes, Females whose mothers received calcium (F-Ca) were shorter, lighter with smaller bones and less bone mineral than those whose mothers received placebo (F-P), differences (SE) ranged from height = − 1.0 (0.5)% to hip BMC − 5.5 (2.3)%. Males from mothers in the calcium group (M-Ca) had greater mid-upper arm circumference (MUAC) (+ 2.0 (1.0)%, p = 0.05) and fat mass (+ 11.6 (5.1)%, p = 0.02) and tended towards greater BMC and size than those whose mothers were in the placebo group (M-P). The differences in anthropometry and body composition were robust to adjustment for current height and weight, whereas all bone differences became non-significant. F-P were taller with more BMC than M-P, whereas F-Ca had similar sized bones and mineral content to M-Ca.
Calcium supplementation of pregnant women with low calcium intakes altered the childhood trajectories of growth and bone and body composition development of their offspring in a sex-specific manner, resulting in slower growth among females compared to placebo and accelerated growth among males by age 8–12 years
Pregnancy-Related Bone Mineral and Microarchitecture Changes in Women Aged 30 to 45 Years
Full text linkAt birth, the neonatal skeleton contains 20 to 30 g calcium (Ca). It is hypothesized maternal bone mineral may be mobilized to support fetal skeletal development, although evidence of pregnancy-induced mineral mobilization is limited. We recruited healthy pregnant (n = 53) and non-pregnant non-lactating (NPNL; n = 37) women aged 30 to 45 years (mean age 35.4 ± 3.8 years) and obtained peripheral quantitative computed tomography (pQCT) and high-resolution pQCT (HR-pQCT) scans from the tibia and radius at 14 to 16 and 34 to 36 weeks of pregnancy, with a similar scan interval for NPNL. Multiple linear regression models were used to assess group differences in change between baseline and follow-up; differences are expressed as standard deviation scores (SDS) ± SEM. Decreases in volumetric bone mineral density (vBMD) outcomes were found in both groups; however, pregnancy-related decreases for pQCT total and trabecular vBMD were −0.65 ± 0.22 SDS and −0.50 ± 0.23 SDS greater (p <.05). HR-pQCT total and cortical vBMD decreased compared with NPNL by −0.49 ± 0.24 SDS and −0.67 ± 0.23 SDS, respectively; trabecular vBMD decreased in both groups to a similar magnitude. Pregnancy-related changes in bone microarchitecture significantly exceeded NPNL change for trabecular number (0.47 ± 0.23 SDS), trabecular separation (−0.54 ± 0.24 SDS), cortical thickness (−1.01 ± 0.21 SDS), and cortical perimeter (0.78 ± 0.23 SDS). At the proximal radius, cortical vBMD and endosteal circumference increased by 0.50 ± 0.23 SDS and 0.46 ± 0.23 SDS, respectively, compared with NPNL, whereas cortical thickness decreased −0.50 ± 0.22 SDS. Pregnancy-related decreases in total and compartment-specific vBMD exceed age-related change at the distal tibia. Changes at the radius were only evident with pQCT at the cortical-rich proximal site and suggest endosteal resorption. Although the magnitude of these pregnancy-related changes in the appendicular skeleton are small, if they reflect global changes across the skeleton at large, they may contribute substantially to the Ca requirements of the fetus.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Life course dietary patterns and bone health in later life in a British birth cohort study
No full textEvidence for the contribution of individual foods and nutrients to bone health is weak. Few studies have considered hypothesis-based dietary patterns and bone health. We investigated whether a protein, calcium and potassium-rich (PrCaK-rich) dietary pattern over the adult life course, was positively associated with bone outcomes at 60-64 years of age. Diet diaries were collected at ages 36, 46, 53 and 60-64 years in 1263 participants (661 women) from the MRC National Survey of Health and Development. DXA and pQCT measurements were obtained at 60-64y, including size-adjusted bone mineral content (SA-BMC) and volumetric bone mineral density (vBMD). A food-based dietary pattern best explaining dietary calcium, potassium and protein intakes (g/1000?kcal) was identified using reduced rank regression. Dietary pattern z-scores were calculated for each individual, at each time point. Individual trajectories in dietary pattern z-scores were modelled to summarise changes in z-scores over the study period. Regression models examined associations between these trajectories and bone outcomes at 60-64y, adjusting for baseline dietary pattern z-score and other confounders. A consistent PrCaK-rich dietary pattern was identified within the population, over time. Mean [SD] dietary pattern z-scores at age 36 and 60-64 years were -0.32[0.97], 2.2[1.5] (women) and -0.35[0.98], 1.7[1.6] (men). Mean trajectory in dietary pattern z-scores [SD] was 0.07[0.02]SD units/year. Among women, a 0.02 SD unit/year higher trajectory in dietary pattern z-score over time was associated with higher SA-BMC (spine 1.40% [95% CI: 0.30,2.51]; hip 1.35% [95% CI: 0.48,2.23]) and vBMD (radius 1.81% [95% CI: 0.13,3.50]) at 60-64 y. No statistically significant associations were found in men. During adulthood, an increasing score for a dietary pattern rich in protein, calcium and potassium was associated with greater SA-BMC at fracture-prone sites in women. This study emphasises the importance of these nutrients, within the context of the whole diet, to bone healt
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Changes in bone mineral density, body composition, vitamin D status and mineral metabolism in urban HIV-positive South African women over 12 months
No full textHIV infection and antiretroviral therapy (ART) are associated with bone loss and poor vitamin D status in Caucasian populations, though their relative roles are not known. No previous studies have examined longitudinal changes in areal bone mineral density (aBMD), measured by DXA, or in vitamin D status in HIV-positive African women. Of 247 premenopausal, urban, black African women from Soweto, South Africa, initially recruited, 187 underwent anthropometry, DXA scanning and blood and urine collections at both baseline and 12 months. Of these, 67 were HIV-negative throughout (Nref), 60 were HIV-positive with preserved CD4 counts at baseline (Ppres) and 60 were HIV-positive with low CD4 counts at baseline, eligible for ART by South African standards of care at the time (Plow). No participant had been exposed to ART at baseline. By 12 months, 51 Plow women had initiated ART, >85% of whom took combined tenofovir disoproxil fumarate (TDF), lamivudine and efavirenz. By 12 months, Plow and Nref, but not Ppres, increased in body weight and fat mass (group-by-timepoint p ≤0.001, p = 0.002 respectively). Plow had significant decreases in aBMD of 2-3%, before and after size adjustment, at the femoral neck (p ≤0.002) and lumbar spine (p ≤0.001), despite significant weight gain. These decreases were associated with increased bone turnover but there were no significant differences or changes over time in vitamin D status, serum phosphate concentrations or renal phosphate handling. Excluding data from 9 Plow women unexposed to ART and 11 Ppres women who had initiated ART accentuated these findings, suggesting the bone loss in Plow was related to ART exposure. This is the first study describing DXA-defined bone loss in HIV-positive Sub-Saharan African women in association with ART. Further work is required to establish if bone loss continues with on-going ART and, if so, whether this results in increased fracture rates
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
