Body composition in Nepalese children using isotope dilution: the production of ethnic-specific calibration equations and an exploration of methodological issues.

Background. Body composition is important as a marker of both current and future health. Bioelectrical impedance (BIA) is a simple and accurate method for estimating body composition, but requires population-specific calibration equations. Objectives. (1) To generate population specific calibration equations to predict lean mass (LM) from BIA in Nepalese children aged 7-9 years. (2) To explore methodological changes that may extend the range and improve accuracy. Methods. BIA measurements were obtained from 102 Nepalese children (52 girls) using the Tanita BC-418. Isotope dilution with deuterium oxide was used to measure total body water and to estimate LM. Prediction equations for estimating LM from BIA data were developed using linear regression, and estimates were compared with those obtained from the Tanita system. We assessed the effects of flexing the arms of children to extend the range of coverage towards lower weights. We also estimated potential error if the number of children included in the study was reduced. Findings. Prediction equations were generated, incorporating height, impedance index, weight and sex as predictors (R (2) 93%). The Tanita system tended to under-estimate LM, with a mean error of 2.2%, but extending up to 25.8%. Flexing the arms to 90° increased the lower weight range, but produced a small error that was not significant when applied to children <16 kg (p 0.42). Reducing the number of children increased the error at the tails of the weight distribution. Conclusions. Population-specific isotope calibration of BIA for Nepalese children has high accuracy. Arm position is important and can be used to extend the range of low weight covered. Smaller samples reduce resource requirements, but leads to large errors at the tails of the weight distribution

Systematic structural characterization of chitooligosaccharides enabled by Automated Glycan Assembly

Chitin, a polymer composed of β(1-4)-linked N-acetyl-glucosamine monomers, and its partially deacetylated analogue chitosan, are abundant biopolymers with outstanding mechanical as well as elastic properties. Their degradation products, chitooligosaccharides (COS), can trigger the innate immune response in humans and plants. Both material and biological properties are dependent on polymer length, acetylation, as well as the pH. Without well-defined samples, a complete molecular description of these factors is still missing. Automated Glycan Assembly (AGA) enabled rapid access to synthetic well-defined COS. Chitin-cellulose hybrid oligomers were prepared as important tools for a systematic structural analysis. Intramolecular interactions, identified by molecular dynamics simulations and NMR analysis, underscore the importance of the chitosan amino group for the stabilization of specific geometries

Systematic Structural Characterization of Chitooligosaccharides Enabled by Automated Glycan Assembly

Chitin, a polymer composed of beta(1-4)-linked N-acetyl-glucosamine monomers, and its partially deacetylated analogue chitosan, are abundant biopolymers with outstanding mechanical as well as elastic properties. Their degradation products, chitooligosaccharides (COS), can trigger the innate immune response in humans and plants. Both material and biological properties are dependent on polymer length, acetylation, as well as the pH. Without well-defined samples, a complete molecular description of these factors is still missing. Automated glycan assembly (AGA) enabled rapid access to synthetic well-defined COS. Chitin-cellulose hybrid oligomers were prepared as important tools for a systematic structural analysis. Intramolecular interactions, identified by molecular dynamics simulations and NMR analysis, underscore the importance of the chitosan amino group for the stabilization of specific geometries

Deoxyfluorination tunes the aggregation of cellulose and chitin oligosaccharides and highlights the role of specific hydroxyl groups in the crystallization process

Cellulose and chitin are abundant structural polysaccharides exploited by nature in a large number of applications thanks to their crystallinity. Chemical modifications are commonly employed to tune polysaccharide physical and mechanical properties, but generate heterogeneous mixtures. Thus, the effect of such modifications is not well understood at the molecular level. In this work, we examined how deoxyfluorination (site and pattern) impact the solubility and aggregation of well-defined cellulose and chitin oligomers. While deoxyfluorination increased solubility in water and lowered the crystallinity of cellulose oligomers, chitin was much less affected by the modification. The OH/F substitution also highlighted the role of specific hydroxyl groups in the crystallization process. This work provides guidelines for the design of cellulose- and chitin-based materials. A similar approach can be imagined to prepare cellulose and chitin analogues capable of withstanding enzymatic degradation

Deoxyfluorination tunes the aggregation of cellulose and chitin oligosaccharides and highlights the role of specific hydroxyl groups in the crystallization process

Cellulose and chitin are abundant structural polysaccharides exploited by nature in a large number of applications thanks to their crystallinity. Chemical modifications are commonly employed to tune polysaccharide physical and mechanical properties, but generate heterogeneous mixtures. Thus, the effect of such modifications is not well understood at the molecular level. In this work, we examined how deoxyfluorination (site and pattern) impact the solubility and aggregation of well-defined cellulose and chitin oligomers. While deoxyfluorination increased solubility in water and lowered the crystallinity of cellulose oligomers, chitin was much less affected by the modification. The OH/F substitution also highlighted the role of specific hydroxyl groups in the crystallization process. This work provides guidelines for the design of cellulose- and chitin-based materials. A similar approach can be imagined to prepare cellulose and chitin analogues capable of withstanding enzymatic degradation

Efficient dynamic events discrimination technique for fiber distributed Brillouin sensors

A technique to detect real time variations of temperature or strain in Brillouin based distributed fiber sensors is proposed and is investigated in this paper. The technique is based on anomaly detection methods such as the RX-algorithm. Detection and isolation of dynamic events from the static ones are demonstrated by a proper processing of the Brillouin gain values obtained by using a standard BOTDA system. Results also suggest that better signal to noise ratio, dynamic range and spatial resolution can be obtained. For a pump pulse of 5 ns the spatial resolution is enhanced, (from 0.541 m obtained by direct gain measurement, to 0.418 m obtained with the technique here exposed) since the analysis is concentrated in the variation of the Brillouin gain and not only on the averaging of the signal along the time

Associations of stunting at 2 years with body composition and blood pressure at 8 years of age: longitudinal cohort analysis from lowland Nepal

BACKGROUND: Stunting remains a very common form of child malnutrition worldwide, particularly in South Asian populations. There is poor understanding of how it develops and how it is associated with subsequent phenotype. SUBJECTS/METHODS: We used data from a longitudinal cohort of children (n = 841) in lowland Nepal to investigate associations of stunting at 2 years with maternal traits and early growth patterns, and with body size and composition, kidney dimensions by ultrasound, lung function by spirometry and blood pressure (BP) at 8 years. RESULTS: Compared to non-stunted children, children stunted at 2 years came from poorer families and had shorter, lighter mothers. They tended to have higher birth order, were born smaller, and remained shorter, lighter and thinner at 8 years. They had lower leg length, lean and fat masses, smaller kidneys, and reduced lung function (all p < 0.0001). These differences persisted with smaller magnitude after adjusting for current height, maternal height and education, family assets and birth order. Stunting was not associated with BP. DISCUSSION: Stunting developed on an inter-generational timescale in this population and its risk increased with birth order. At 8 years, children stunted at 2 years had deficits in tissue masses and some aspects of physical function that were only partially attributable to their persisting short height and maternal phenotype. This suggests that the early stunting is associated with greater deficits in long-term outcomes than would be expected from the persistent short stature alone

Effectiveness of female community health volunteers in the detection and management of low-birth-weight in Nepal

Introduction: Low birth weight (LBW) is a major risk factor for neonatal death. However, most neonates in low-income countries are not weighed at birth. This results in many LBW infants being overlooked. Female community health volunteers (FCHVs) in Nepal are non-health professionals who are living in local communities and have already worked in a field of reproductive and child health under the government of Nepal for more than 20 years. The effectiveness of involving FCHVs to detect LBW infants and to initiate prompt action for their care was studied in rural areas of Nepal. Methods: FCHVs were tasked with weighing all neonates born in selected areas using color-coded spring scales. Supervisors repeated each weighing using electronic scales as the gold standard comparator. Data on the relative birth sizes of the infants, as assessed by their mothers, were also collected and compared with the measured weights. Each of the 205 FCHVs involved in the study was asked about the steps that she would take when she came across a LBW infant, and knowledge of zeroing a spring scale was also assessed through individual interviews. The effect of the background social characteristics of the FCHVs on their performance was examined by logistic regression. This study was nested within a community-based neonatal sepsis-management intervention surveillance system, which facilitated an assessment of the performance of the FCHVs in weighing neonates, coverage of FCHVs’ visits, and weighing of babies through maternal interviews. Results: A total of 462 babies were weighed, using both spring scales and electronic scales, within 72 hours of birth. The prevalence of LBW, as assessed by the gold standard method, was 28%. The sensitivity of detection of LBW by FCHVs was 89%, whereas the sensitivity of the mothers’ perception of size at birth was only 40%. Of the 205 FCHVs participating in the study, 70% of FCHVs understood what they should do when they identified LBW and very low birth weight (VLBW) infants. Ninety-six per cent could describe how to zero a scale and approximately 50% could do it correctly. Seventy-seven per cent of FCHVs weighed infants at least once during the study period, and 19 of them (12%) miscategorized infant weights. Differences were not detected between the background social characteristics of FCHVs who miscategorized infants and those who did not. On the basis of maternal reporting, 67% of FCHVs who visited infants had weighed them. Conclusions: FCHVs are able to correctly identify LBW and VLBW infants using spring scales and describe the correct steps to take after identification of these infants. Use of FCHVs as newborn care providers allows for utilization of their logistical, geographical, and cultural strengths, particularly a high level of access to neonates, that can complement the Nepalese healthcare system. Providing additional training to and increasing supervision of local FCHVs regarding birth weight measurement will increase the identification of high-risk neonates in resource-limited settings

Effect of antenatal multiple micronutrient supplementation on anthropometry and blood pressure in mid-childhood in Nepal: follow-up of a double-blind randomised controlled trial

Background: In a randomized controlled trial in southern Nepal, we found that children born to mothers who had taken multiple micronutrient supplements during pregnancy had mean birthweight 77 g greater than a control group allocated to iron and folic acid supplements. They were a mean 204 g heavier at 2·5 years of age and their systolic blood pressure was a mean 2·5 mmHg lower. We followed the same children up in mid-childhood, hypothesizing that these differences would be sustained. Methods: We identified children from the original trial and measured anthropometry, body composition using bioelectrical impedance (with population-specific isotope calibration), blood pressure, and renal dimensions by ultrasound. We documented socieconomic status, household food security, and air pollution.Results: We assessed 841 children (422 control, 419 intervention) at mean age 8·5 years. Unadjusted differences (intervention minus control) were 0·05 z-scores (95% CI -0·09, 0·19) in weight-for-age, 0·02 z-scores (-0·10, 0·15) in height-for-age, and 0·04 z-scores (-0·09, 0·18) in body-mass-index-for-age. There was no difference in blood pressure. Adjusted differences were similar for all outcomes. Discussion: Differences in phenotype between children born to mothers who received antenatal multiple micronutrient or iron and folate supplements were not apparent at 8·5 years. Our findings did not extend to physiological differences or potential longer-term effects