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Walters WA, Ley C, Hastie T, Ley RE, Parsonnet J. A modified Michaelis-Menten equation estimates growth from birth to 3 years in healthy babies in the USA. BMC Med Res Methodol 2024; 24:27. [PMID: 38302887 PMCID: PMC10832211 DOI: 10.1186/s12874-024-02145-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 01/08/2024] [Indexed: 02/03/2024] Open
Abstract
BACKGROUND Standard pediatric growth curves cannot be used to impute missing height or weight measurements in individual children. The Michaelis-Menten equation, used for characterizing substrate-enzyme saturation curves, has been shown to model growth in many organisms including nonhuman vertebrates. We investigated whether this equation could be used to interpolate missing growth data in children in the first three years of life and compared this interpolation to several common interpolation methods and pediatric growth models. METHODS We developed a modified Michaelis-Menten equation and compared expected to actual growth, first in a local birth cohort (N = 97) then in a large, outpatient, pediatric sample (N = 14,695). RESULTS The modified Michaelis-Menten equation showed excellent fit for both infant weight (median RMSE: boys: 0.22 kg [IQR:0.19; 90% < 0.43]; girls: 0.20 kg [IQR:0.17; 90% < 0.39]) and height (median RMSE: boys: 0.93 cm [IQR:0.53; 90% < 1.0]; girls: 0.91 cm [IQR:0.50;90% < 1.0]). Growth data were modeled accurately with as few as four values from routine well-baby visits in year 1 and seven values in years 1-3; birth weight or length was essential for best fit. Interpolation with this equation had comparable (for weight) or lower (for height) mean RMSE compared to the best performing alternative models. CONCLUSIONS A modified Michaelis-Menten equation accurately describes growth in healthy babies aged 0-36 months, allowing interpolation of missing weight and height values in individual longitudinal measurement series. The growth pattern in healthy babies in resource-rich environments mirrors an enzymatic saturation curve.
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Affiliation(s)
- William A Walters
- Department of Microbiome Science, Max Planck Institute for Biology, Tübingen, Germany
| | - Catherine Ley
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA, 94305-5170, USA.
| | - Trevor Hastie
- Departments of Statistics and of Biomedical Data Sciences, Stanford University, Stanford, CA, USA
| | - Ruth E Ley
- Department of Microbiome Science, Max Planck Institute for Biology, Tübingen, Germany
| | - Julie Parsonnet
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA, 94305-5170, USA
- Department of Epidemiology and Population Health, Stanford University School of Medicine, Stanford, CA, USA
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Walters W, Ley C, Hastie T, Ley R, Parsonnet J. A modified Michaelis-Menten equation estimates growth from birth to 3 years in healthy babies in the US. RESEARCH SQUARE 2023:rs.3.rs-2375831. [PMID: 36711501 PMCID: PMC9882604 DOI: 10.21203/rs.3.rs-2375831/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Background and Objectives Standard pediatric growth curves cannot be used to impute missing height or weight measurements in individual children. The Michaelis-Menten equation, used for characterizing substrate-enzyme saturation curves, has been shown to model growth in many organisms including nonhuman vertebrates. We investigated this equation could be used to interpolate missing growth data in children in the first three years of life. Methods We developed a modified Michaelis-Menten equation and compared expected to actual growth, first in a local birth cohort (N=97) then in a large, outpatient, pediatric sample (N=14,695). Results The modified Michaelis-Menten equation showed excellent fit for both infant weight (median RMSE: boys: 0.22kg [IQR:0.19; 90%<0.43]; girls: 0.20kg [IQR:0.17; 90%<0.39]) and height (median RMSE: boys: 0.93cm [IQR:0.53; 90%<1.0]; girls: 0.91cm [IQR:0.50;90%<1.0]). Growth data were modeled accurately with as few as four values from routine well-baby visits in year 1 and seven values in years 1-3; birth weight or length was essential for best fit. Conclusions A modified Michaelis-Menten equation accurately describes growth in healthy babies aged 0-36 months, allowing interpolation of missing weight and height values in individual longitudinal measurement series. The growth pattern in healthy babies in resource-rich environments mirrors an enzymatic saturation curve.
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Affiliation(s)
| | | | | | - Ruth Ley
- Max Plank Institute for Developmental Biology
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Walters W, Ley C, Hastie T, Ley R, Parsonnet J. A modified Michaelis-Menten equation estimates growth from birth to 3 years in healthy babies in the US. RESEARCH SQUARE 2023:rs.3.rs-2375831. [PMID: 36711501 PMCID: PMC9882604 DOI: 10.21203/rs.3.rs-2375831/v2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/13/2024]
Abstract
Background and Objectives Standard pediatric growth curves cannot be used to impute missing height or weight measurements in individual children. The Michaelis-Menten equation, used for characterizing substrate-enzyme saturation curves, has been shown to model growth in many organisms including nonhuman vertebrates. We investigated this equation could be used to interpolate missing growth data in children in the first three years of life. Methods We developed a modified Michaelis-Menten equation and compared expected to actual growth, first in a local birth cohort (N=97) then in a large, outpatient, pediatric sample (N=14,695). Results The modified Michaelis-Menten equation showed excellent fit for both infant weight (median RMSE: boys: 0.22kg [IQR:0.19; 90%<0.43]; girls: 0.20kg [IQR:0.17; 90%<0.39]) and height (median RMSE: boys: 0.93cm [IQR:0.53; 90%<1.0]; girls: 0.91cm [IQR:0.50;90%<1.0]). Growth data were modeled accurately with as few as four values from routine well-baby visits in year 1 and seven values in years 1-3; birth weight or length was essential for best fit. Conclusions A modified Michaelis-Menten equation accurately describes growth in healthy babies aged 0-36 months, allowing interpolation of missing weight and height values in individual longitudinal measurement series. The growth pattern in healthy babies in resource-rich environments mirrors an enzymatic saturation curve.
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Affiliation(s)
| | | | | | - Ruth Ley
- Max Plank Institute for Developmental Biology
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Yang Y, Wang L, Yang Y, Wu X, Xu L, Bi C. Z-score regression model for coronary artery diameter in healthy Chinese Han children. Acta Radiol 2023; 64:798-805. [PMID: 35306860 DOI: 10.1177/02841851221085685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Coronary artery distension and aneurysm are complications of Kawasaki disease in children. PURPOSE To develop a Z-score regression model for coronary artery diameter in children that could be used as reference. MATERIAL AND METHODS This retrospective analysis included children with normal heart structure between March 2013 and April 2017. Body surface area (BSA) was calculated. The diameters of the right coronary, left main coronary, left anterior descending, and circumflex arteries were measured by echocardiography. Pearson correlation analysis was used to establish linear, exponential, logarithmic, power, and square root regression models. RESULTS The analysis included 509 children (280 boys) aged 1 day to 15.2 years. Coronary artery diameters were significantly correlated with age, height, body mass, BSA, and BSA (r = 0.663-0.826; P < 0.05), with a stronger correlation for BSA than BSA (P < 0.05). The adjusted determination coefficients (Ra2) were higher for the exponential and square root models than for the other models (P < 0.05). The random error term variance was constant for the exponential model (P > 0.05), and processing with the weighted least-square methods eliminated heteroscedasticity in the other models. The Z-scores were normally distributed for the exponential and square root models (P > 0.05). CONCLUSION Overall, the square root model was the optimal equation for the calculation of coronary artery Z-score in Chinese Han children. This model could be used to facilitate the diagnosis of coronary artery distension in children with suspected Kawasaki disease.
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Affiliation(s)
- Yanzhang Yang
- Department of Pediatrics, 117872Hebei General Hospital, Shijiazhuang, Hebei, PR China
| | - Li Wang
- Department of Pediatrics, Shijiazhuang Fifth Hospital, Shijiazhuang, Hebei, PR China
| | - Yanfang Yang
- Department of Medical Imaging, Gaocheng Integrated Traditional Chinese and Western Medicine Hospital, Shijiazhuang, Hebei, PR China
| | - Xiaojing Wu
- Department of Pediatrics, 117872Hebei General Hospital, Shijiazhuang, Hebei, PR China
| | - Lijin Xu
- Department of Pediatrics, 117872Hebei General Hospital, Shijiazhuang, Hebei, PR China
| | - Changbo Bi
- Department of Pediatrics, 117872Hebei General Hospital, Shijiazhuang, Hebei, PR China
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Recognizing and treating child overweight and obesity. JAAPA 2021; 33:47-50. [PMID: 33234896 DOI: 10.1097/01.jaa.0000721676.28303.7c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Primary care providers can help prevent and address child overweight and obesity, conditions that can affect children's present and future health as well as their psychologic, emotional, and social well-being. This article describes approaches to preventing, identifying, and addressing overweight and obesity using empathetic, practical, family-focused recommendations and actions.
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Frongillo EA, Leroy JL, Lapping K. Appropriate Use of Linear Growth Measures to Assess Impact of Interventions on Child Development and Catch-Up Growth. Adv Nutr 2019; 10:372-379. [PMID: 30805630 PMCID: PMC6520037 DOI: 10.1093/advances/nmy093] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 08/28/2018] [Accepted: 10/21/2018] [Indexed: 01/19/2023] Open
Abstract
Linear growth is increasingly used as the sole or primary outcome for evaluating interventions, but impact is often not seen. Sometimes there is interest in whether children catch up to where they otherwise would have been had detrimental conditions not occurred, but the literature is confusing because of claims for evidence of catch-up growth based on inappropriate methods. This article examines the use of linear growth measures to evaluate intervention impact and catch-up. Focus on linear growth as a measure of impact has resulted in a lack of demonstrable intervention effects, evaluations that do not use measures responsive to nutrition-sensitive and integrated interventions, insufficient emphasis on adolescent girls and women before conception and children after the first 1000 d, and insufficient investment in developing other measures. Nutrition interventions may benefit children but may not discernibly affect linear growth deficits in immediate or intermediate periods. Interventions intended to affect one domain may have positive or negative impacts on others. Child nutrition and growth are part of early childhood development; the focus should be on improving conditions in which children grow and develop throughout childhood and adolescence because poor conditions in a population affect all children. To assess the impact of nutrition interventions, it is important to use a broad set of measures and indicators of outcomes and immediate and underlying determinants. The 4 criteria for demonstrating catch-up in growth, which are much more stringent than those for demonstrating intervention impact, require demonstration of the following: 1) an inhibiting condition and 2) reduced velocity during 1 period, 3) followed by alleviation of or compensation for the inhibiting condition, and 4) higher-than-normal velocity during a subsequent period. Partial catch-up growth is sometimes possible when constraints are removed, but whether it is beneficial to the child is not clear. Research is needed to develop, refine, and validate measures and indicators for the purposes intended.
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Affiliation(s)
- Edward A Frongillo
- Department of Health Promotion, Education, and Behavior, University of South Carolina, Columbia, SC
| | - Jef L Leroy
- Poverty, Health, and Nutrition Division, International Food Policy Research Institute, Washington, DC
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Biomarkers of Systemic Inflammation and Growth in Early Infancy are Associated with Stunting in Young Tanzanian Children. Nutrients 2018; 10:nu10091158. [PMID: 30149537 PMCID: PMC6164697 DOI: 10.3390/nu10091158] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 08/15/2018] [Accepted: 08/22/2018] [Indexed: 01/08/2023] Open
Abstract
Stunting can afflict up to one-third of children in resource-constrained countries. We hypothesized that low-grade systemic inflammation (defined as elevations in serum C-reactive protein or alpha-1-acid glycoprotein) in infancy suppresses the growth hormone–insulin-like growth factor (IGF) axis and is associated with subsequent stunting. Blood samples of 590 children from periurban Dar es Salaam, Tanzania, were obtained at 6 weeks and 6 months of age as part of a randomized controlled trial. Primary outcomes were stunting, underweight, and wasting (defined as length-for-age, weight-for-age and weight-for-length z-scores < −2) between randomization and endline (18 months after randomization). Cox proportional hazards models were constructed to estimate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) of time to first stunting, underweight, and wasting as outcomes, with measures of systemic inflammation, insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) as exposures, adjusting for numerous demographic and clinical variables. The incidences of subsequent stunting, underweight, and wasting were 26%, 20%, and 18%, respectively. In multivariate analyses, systemic inflammation at 6 weeks of age was significantly associated with stunting (HR: 2.14, 95% CI: 1.23, 3.72; p = 0.002). Children with higher levels of IGF-1 at 6 weeks were less likely to become stunted (HR: 0.58, 95% CI: 0.37, 0.93; p for trend = 0.019); a similar trend was noted in children with higher levels of IGF-1 at 6 months of age (HR: 0.50, 95% CI: 0.22, 1.12; p for trend = 0.07). Systemic inflammation occurs as early as 6 weeks of age and is associated with the risk of future stunting among Tanzanian children.
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Syed S, Iqbal NT, Sadiq K, Ma JZ, Akhund T, Xin W, Moore SR, Liu E, Qureshi S, Gosselin K, Gewirtz A, Duggan CP, Ali SA. Serum anti-flagellin and anti-lipopolysaccharide immunoglobulins as predictors of linear growth faltering in Pakistani infants at risk for environmental enteric dysfunction. PLoS One 2018; 13:e0193768. [PMID: 29509790 PMCID: PMC5839587 DOI: 10.1371/journal.pone.0193768] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 02/17/2018] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Environmental Enteric Dysfunction (EED) in children from low-income countries has been linked to linear growth declines. There is a critical need to identify sensitive and early EED biomarkers. OBJECTIVE Determine whether levels of antibodies against bacterial components flagellin (flic) and lipopolysaccharide (LPS) predict poor growth. DESIGN/METHODS In a prospective birth cohort of 380 children in rural Pakistan blood and stool samples were obtained at ages 6 and 9 months. Linear mixed effects models were used to examine longitudinal associations between quartiles of anti-flic and anti-LPS antibodies and changes in LAZ, WAZ and WLZ scores. Spearman's correlations were measured between anti-flic and anti-LPS immunoglobulins with measures of systemic/enteric inflammation and intestinal regeneration. RESULTS Anti-LPS IgA correlated significantly with CRP, AGP and Reg1 serum at 6mo and with MPO at 9mo. In multivariate analysis at 6mo of age, higher anti-LPS IgA levels predicted greater declines in LAZ scores over subsequent 18mo (comparing highest to lowest quartile, β (SE) change in LAZ score/year = -0.313 (0.125), p-value = 0.013). Anti-flic Ig A in the two highest quartiles measured at 9mo of age had declines in LAZ of -0.269 (0.126), p = 0.033; and -0.306 (0.129), p = 0.018 respectively, during the subsequent 18mo of life, compared to those in the lowest quartile of anti-flic IgA. CONCLUSIONS AND RELEVANCE Elevated anti-flic IgA and anti-LPS IgA antibodies at 6 and 9mo, predict declines in linear growth. Systemic and enteric inflammation correlated with anti-LPS IgA provides mechanistic considerations for potential future interventions.
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Affiliation(s)
- Sana Syed
- Department of Pediatrics, University of Virginia, Charlottesville, VA, United States of America
- Department of Pediatrics, the Aga Khan University, Karachi, Pakistan
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, MA, United States of America
| | - Najeeha T. Iqbal
- Department of Pediatrics, the Aga Khan University, Karachi, Pakistan
| | - Kamran Sadiq
- Department of Pediatrics, the Aga Khan University, Karachi, Pakistan
| | - Jennie Z. Ma
- Department of Public Health Sciences, University of Virginia, Charlottesville, VA, United States of America
| | - Tauseef Akhund
- Department of Pediatrics, the Aga Khan University, Karachi, Pakistan
| | - Wenjun Xin
- Department of Public Health Sciences, University of Virginia, Charlottesville, VA, United States of America
| | - Sean R. Moore
- Department of Pediatrics, University of Virginia, Charlottesville, VA, United States of America
| | - Enju Liu
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, MA, United States of America
| | - Shahida Qureshi
- Department of Pediatrics, the Aga Khan University, Karachi, Pakistan
| | - Kerri Gosselin
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, MA, United States of America
| | - Andrew Gewirtz
- Center for Inflammation Immunity & Infection, Georgia State University, Atlanta, GA, United States of America
| | - Christopher P. Duggan
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, MA, United States of America
- Departments of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, MA, United States of America
- Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, United States of America
| | - S. Asad Ali
- Department of Pediatrics, the Aga Khan University, Karachi, Pakistan
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Mosites E, Thumbi SM, Otiang E, McElwain TF, Njenga MK, Rabinowitz PM, Rowhani-Rahbar A, Neuhouser ML, May S, Palmer GH, Walson JL. Relations between Household Livestock Ownership, Livestock Disease, and Young Child Growth. J Nutr 2016; 146:1118-24. [PMID: 27075911 PMCID: PMC4841921 DOI: 10.3945/jn.115.225961] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 03/07/2016] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND In resource-limited settings in which child malnutrition is prevalent, humans live in close proximity to household livestock. However, the relation between household livestock and child nutrition represents a considerable knowledge gap. OBJECTIVE We assessed whether household livestock ownership or livestock disease episodes were associated with growth in young children in western Kenya. METHODS We incorporated monthly anthropometric measurements for children <5 y of age into an ongoing linked human and animal surveillance cohort in rural western Kenya. Using linear mixed models adjusted for age, sex, and household wealth, we tested whether baseline household livestock ownership was related to baseline child height for age or prospective growth rate. We also evaluated whether livestock disease episodes were associated with child growth rate over 11 mo of follow-up. RESULTS We collected data on 925 children over the course of follow-up. Greater household livestock ownership at baseline was not related to baseline child height-for-age z score (adjusted β: 0.01 SD; 95% CI: -0.02, 0.04 SD) or child growth rate (adjusted β: 0.02 cm/y; 95% CI: -0.03, 0.07 cm/y). Livestock disease episodes were not significantly associated with child growth across the entire cohort (adjusted β: -0.007 cm/mo; 95% CI: -0.02, 0.006 cm/mo). However, children in households with livestock digestive disease between June and November gained less height than did children in households that did not report livestock disease (β: -0.063 cm/mo; 95% CI: -0.112, -0.016 cm/mo). Children <2 y of age in households with livestock digestive disease gained less weight than did those who did not report disease (β: -0.033 kg/mo; 95% CI: -0.063, -0.003 kg/mo). CONCLUSION In this cohort of young children in western Kenya, we did not find an association between ownership of livestock and child growth status. However, disease episodes in household livestock may be related to a lower child growth rate in some groups.
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Affiliation(s)
- Emily Mosites
- Department of Epidemiology, Paul G Allen School for Global Animal Health, Washington State University, Pullman, WA;
| | - Samuel M Thumbi
- Paul G Allen School for Global Animal Health, Washington State University, Pullman, WA
| | | | - Terry F McElwain
- Paul G Allen School for Global Animal Health, Washington State University, Pullman, WA
| | - MK Njenga
- Paul G Allen School for Global Animal Health, Washington State University, Pullman, WA
| | | | | | - Marian L Neuhouser
- Department of Epidemiology,,Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA
| | | | - Guy H Palmer
- Paul G Allen School for Global Animal Health, Washington State University, Pullman, WA
| | - Judd L Walson
- Department of Epidemiology,,Department of Global Health,,Department of Medicine,,Department of Pediatrics, University of Washington, Seattle, WA
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Abstract
Normal growth in children is a reflection of general health and is the result of a complex interaction between genetic, nutritional, and hormonal factors. From conception through infancy, growth is mostly driven by maternal nutrition and the in utero environment. Genetic factors, growth and thyroid hormones, ghrelin, and sex steroids have a more prominent influence later. Normal growth is not linear; it is marked by periods of growth spurts, particularly during puberty, separated by periods of slow or immeasurable growth. There is often a period of growth deceleration observed before the onset of puberty, with maximal pubertal growth spurts occurring at Tanner stage III for girls and Tanner stage IV for boys. This is caused primarily by the combined effect of the increased amplitude of growth hormone pulses and sex steroids. Short stature (SS), which is the subject of this review, is defined as a length or height more than 2 standard deviations below the mean for age and gender, which corresponds to a percentile below 2.5%. Taking a thorough patient history and completing a comprehensive physical examination are some of the most important diagnostic tools for pediatricians to use in the diagnosis of SS, and in making appropriate referrals as needed.
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Atun-Einy O, Berger SE, Ducz J, Sher A. Strength of Infants' Bimanual Reaching Patterns is Related to the Onset of Upright Locomotion. INFANCY 2013. [DOI: 10.1111/infa.12030] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Sarah E. Berger
- Department of Psychology; The College of Staten Island; The Graduate Center of the City University of New York
- Department of Psychology; The Graduate Center of the City University of New York
| | - Jennifer Ducz
- Department of Psychology; The Graduate Center of the City University of New York
| | - Anat Sher
- Department of Counseling and Human Development; University of Haifa
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12
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Rijken MJ, Papageorghiou AT, Thiptharakun S, Kiricharoen S, Dwell SLM, Wiladphaingern J, Pimanpanarak M, Kennedy SH, Nosten F, McGready R. Ultrasound evidence of early fetal growth restriction after maternal malaria infection. PLoS One 2012; 7:e31411. [PMID: 22347473 PMCID: PMC3276538 DOI: 10.1371/journal.pone.0031411] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 01/10/2012] [Indexed: 11/30/2022] Open
Abstract
Background Intermittent preventive treatment (IPT), the main strategy to prevent malaria and reduce anaemia and low birthweight, focuses on the second half of pregnancy. However, intrauterine growth restriction may occur earlier in pregnancy. The aim of this study was to measure the effects of malaria in the first half of pregnancy by comparing the fetal biparietal diameter (BPD) of infected and uninfected women whose pregnancies had been accurately dated by crown rump length (CRL) before 14 weeks of gestation. Methodology/Principal Findings In 3,779 women living on the Thai-Myanmar border who delivered a normal singleton live born baby between 2001–10 and who had gestational age estimated by CRL measurement <14 weeks, the observed and expected BPD z-scores (<24 weeks) in pregnancies that were (n = 336) and were not (n = 3,443) complicated by malaria between the two scans were compared. The mean (standard deviation) fetal BPD z-scores in women with Plasmodium (P) falciparum and/or P.vivax malaria infections were significantly lower than in non-infected pregnancies; −0.57 (1.13) versus −0.10 (1.17), p<0.001. Even a single or an asymptomatic malaria episode resulted in a significantly lower z-score. Fetal female sex (p<0.001) and low body mass index (p = 0.01) were also independently associated with a smaller BPD in multivariate analysis. Conclusions/Significance Despite early treatment in all positive women, one or more (a)symptomatic P.falciparum or P.vivax malaria infections in the first half of pregnancy result in a smaller than expected mid-trimester fetal head diameter. Strategies to prevent malaria in pregnancy should include early pregnancy.
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McBrien Jr. CS, Vezzoni A, Conzemius MG. Growth Dynamics of the Canine Proximal Tibial Physis. Vet Surg 2011; 40:389-94. [DOI: 10.1111/j.1532-950x.2011.00825.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Abstract
Developmental trajectories provide the empirical foundation for theories about change processes during development. However, the ability to distinguish among alternative trajectories depends on how frequently observations are sampled. This study used real behavioral data, with real patterns of variability, to examine the effects of sampling at different intervals on characterization of the underlying trajectory. Data were derived from a set of 32 infant motor skills indexed daily during the first 18 months. Larger sampling intervals (2-31 days) were simulated by systematically removing observations from the daily data and interpolating over the gaps. Infrequent sampling caused decreasing sensitivity to fluctuations in the daily data: Variable trajectories erroneously appeared as step functions, and estimates of onset ages were increasingly off target. Sensitivity to variation decreased as an inverse power function of sampling interval, resulting in severe degradation of the trajectory with intervals longer than 7 days. These findings suggest that sampling rates typically used by developmental researchers may be inadequate to accurately depict patterns of variability and the shape of developmental change. Inadequate sampling regimes therefore may seriously compromise theories of development.
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Affiliation(s)
- Karen E Adolph
- Department of Psychology, New York University, New York, NY 10003, USA.
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NeuroRhythmics: software for analyzing time-series measurements of saltatory movements in neuronal processes. J Neurosci Methods 2008; 173:147-52. [PMID: 18572249 DOI: 10.1016/j.jneumeth.2008.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Revised: 05/09/2008] [Accepted: 05/10/2008] [Indexed: 11/22/2022]
Abstract
Time-lapse imaging of living neurons both in vivo and in vitro has revealed that the growth of axons and dendrites is highly dynamic and characterized by alternating periods of extension and retraction. These growth dynamics are associated with important features of neuronal development and are differentially affected by experimental treatments, but the underlying cellular mechanisms are poorly understood. NeuroRhythmics was developed to semi-automate specific quantitative tasks involved in analysis of two-dimensional time-series images of processes that exhibit saltatory elongation. This software provides detailed information on periods of growth and nongrowth that it identifies by transitions in elongation (i.e. initiation time, average rate, duration) and information regarding the overall pattern of saltatory growth (i.e. time of pattern onset, frequency of transitions, relative time spent in a state of growth vs. nongrowth). Plots and numeric output are readily imported into other applications. The user has the option to specify criteria for identifying transitions in growth behavior, which extends the potential application of the software to neurons of different types or developmental stage and to other time-series phenomena that exhibit saltatory dynamics. NeuroRhythmics will facilitate mechanistic studies of periodic axonal and dendritic growth in neurons.
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