No abstract

Resting metabolic rate (RMR) quantifies the minimal energy required to sustain vital body functions and is a crucial component of childhood development. While inter-individual variations in RMR have been studied for over a century they are poorly understood. Wang (Am. J. Hum., 2012) has modelled mean RMR per unit body mass (RMR/BM) in children grouped into age classes one year apart; this model is able to explain the variation in RMR/BM very accurately in a reference Caucasian dataset based on the relative masses of four major organs (liver, kidney, brain, heart) and the residual mass. However, it is not clear if it applies to other ethnicities, especially when the variation in the RMR is observed to be large in a population. Here we address the extent to which such a model can be adapted to explain RMR/BM in Indian children. Here we present two novel phenomenological models that describe the mean RMR/BM stratified by age in Indian children and adolescents, using data from the Multi-Centre Study (MCS) and RMR-USG. MCS is a cross-sectional dataset on 495 (235 girls) children aged 9 to 19 years with anthropometric, body composition and RMR measurements. RMR-USG consists of anthropometric data, RMR, and liver and kidney volume measured through ultrasonography in nine girls and nine boys aged 6 to 8 years. The mean RMR/BM in Indian children is observed to be significantly lower compared to their Caucasian counterparts, except in boys in the age groups 9 to 11 years and 12 to 13 years. The first is a modified Wang model in which the relative masses of four major organs are assumed to be uniformly lowered for Indian children. Theoretical predictions of size are not uniformly borne out in a pilot validation study, however, the relative mass of the kidney is indeed found to be significantly lower. We then present another version of the Wang model to demonstrate that changes in body composition alone can also explain the Indian data. Either model can be thus used phenomenologically to estimate mean RMR/BM by age in Indian children; however, understanding the mechanistic basis of variation in RMR/BM remains an open problem.

Background: Resting metabolic rate (RMR) quantifies the minimal energy required to sustain vital body functions and is a crucial component of childhood development. Mean RMR per unit body mass (RMR/BM) has very accurately been modelled in references for Caucasian adolescents.Objectives: Here we address the extent to which such a model can be adapted to explain RMR/BM in Indian children.Subjects and Methods: The multicenter study (MCS) is a cross-sectional dataset on 495 children (235 girls and 260 boys) aged 9 to 19 years with anthropometric, body composition, and RMR measurements. The RMR-ultrasonography study (RMR-USG) consists of anthropometric data, RMR, and liver and kidney volume measured through ultrasonography in nine girls and nine boys aged 6 to 8 years.Results: The mean RMR/BM in Indian children is significantly lower compared to their Caucasian counterparts, except in boys in the age group 9–13 years. We present two novel phenomenological models that describe the mean RMR/BM stratified by age in Indian children and adolescents. The first is a modified Wang model in which the relative masses of four major organs are assumed to be uniformly lowered for Indian children. Theoretical predictions of liver size are not uniformly borne out in a pilot validation study; however, the relative mass of the kidney is found to be significantly lower. The second model demonstrates that changes in body composition alone can also explain the Indian data.Conclusion: A modified Wang model in which the relative masses of four major organs are assumed to be uniformly lower in Indian children and differences in body composition can be used to estimate mean RMR/BM by age in Indian children; however, understanding the mechanistic basis of variation in RMR/BM remains an open problem.

Background. Height growth is affected by longterm childhood morbidity. Objectives. To compare the growth curves of Indian children diagnosed with Type-1 diabetes mellitus (T1DM) and a control group of children without diabetes, and to see how parental height and disease severity affect the growth pattern. Subjects and Methods. The data came from: (i) the Sweetlings T1DM (STDM) study with 460 subjects aged 4–19 years, previously diagnosed with T1DM and followed for 2–6 (median 3) years, with repeat measurements of height and glycated hemoglobin (HbA1c), and (ii) the Pune School-Children Growth (PSCG) study with 1,470 subjects aged 4–19 years, and height measured annually for median 6 years. Height growth was modeled using SuperImposition by Translation and Rotation (SITAR), a mixed effects model which fits a cubic spline mean curve and summarizes individual growth in terms of differences in mean size, and pubertal timing and intensity. Results. SITAR explained 99% of the variance in height, the mean curves by sex showing that compared to controls, the children with diabetes were shorter (by 4/5 cm for boys/girls), with a later (by 1/6 months) and less intense (−5%/−10%) pubertal growth spurt. Adjusted for mean height, timing and intensity, the diabetic and control mean curves were very similar in shape. SITAR modeling showed that mean HbA1c peaked at 10.5% at age 15 years, 1.0% higher than earlier in childhood. Individual growth patterns were highly significantly related to parental height, age at diabetes diagnosis, diabetes duration, and mean HbA1c. Mean height was 3.4 cm more per + 1 SD midparental height, and in girls, 2 cm less per + 1 SD HbA1c. Conclusion. The results show that the physiological response to T1DM is to grow more slowly, and to delay and extend the pubertal growth spurt. The effects are dose-related, with more severe disease associated with greater growth faltering.