Michelle Lampl

Milk- and solid-feeding practices and daycare attendance are associated with differences in bacterial diversity, predominant communities, and metabolic and immune function of the infant gut microbiome

The development of the infant intestinal microbiome in response to dietary and other exposures may shape long-term metabolic and immune function. We examined differences in the community structure and function of the intestinal microbiome between four feeding groups, exclusively breastfed infants before introduction of solid foods (EBF), non-exclusively breastfed infants before introduction of solid foods (non-EBF), EBF infants after introduction of solid foods (EBF+S), and non-EBF infants after introduction of solid foods (non-EBF+S), and tested whether out-of-home daycare attendance was associated with differences in relative abundance of gut bacteria. Bacterial 16S rRNA amplicon sequencing was performed on 49 stool samples collected longitudinally from a cohort of 9 infants (5 male, 4 female). PICRUSt metabolic inference analysis was used to identify metabolic impacts of feeding practices on the infant gut microbiome. Sequencing data identified significant differences across groups defined by feeding and daycare attendance. Non-EBF and daycare-attending infants had higher diversity and species richness than EBF and non-daycare attending infants. The gut microbiome of EBF infants showed increased proportions of Bifidobacterium and lower abundance of Bacteroidetes and Clostridiales than non-EBF infants. PICRUSt analysis indicated that introduction of solid foods had a marginal impact on the microbiome of EBF infants (24 enzymes overrepresented in EBF+S infants). In contrast, over 200 bacterial gene categories were overrepresented in non-EBF+S compared to non-EBF infants including several bacterial methyl-accepting chemotaxis proteins (MCP) involved in signal transduction. The identified differences between EBF and non-EBF infants suggest that breast milk may provide the gut microbiome with a greater plasticity (despite having a lower phylogenetic diversity) that eases the transition into solid foods.

Evidence of saltatory growth in infancy

Auxological measurements were taken weekly (n = 10), semi‐weekly (n = 20), and daily (n = 3) during the first 21 months of life on a sample of normal infants (21 females and 12 males). The serial length measurements are reported. All subjects grew in length during episodic growth saltuses of short duration, with amplitudes of 0.5–2.0 cm during measurements intervals (1 day to 1 week), separated by periods of no measurable growth (2 days to 2 months). The periods of stasis between growth episodes are not positively associated with illness (P = 0.000). These data support the hypothesis that normal human growth during the first 2 years proceeds by pulsatile growth saltuses of substantial amplitude and rapid duration punctuating static intervals. Individual variability in the amplitude and frequency of growth saltuses may account for variation in attained length and growth velocity.

The effects of protein supplementation on the growth and skeletal maturation of New Guinean school children.

SummaryThe response to protein supplementation was studied in 86 Bundi children, aged 7·7 to 13·0 years, in the New Guinea highlands. Group 1 (22 males, 8 females) served as a control and received only their normal school diet, averaging 5440 kJ and 11 g protein per day. Group 2 children (22 males, 8 females) were supplemented with 10 g of protein per day for five days a week and group 3 (18 males, 8 females) received 20 g protein per day. The supplement was skim milk powder and the experiment lasted for eight months. Increments of growth and of skeletal maturation of individuals were analysed, by group, for the eight-month period. Height, weight, skinfold thickness (triceps and subscapular), compact bone breadths of the second metacarpal, and Tanner-Whitehouse bone maturity scores were studied. Supplemented children showed increased growth in height, weight, and periosteal bone breadth, as well as increased increments of skeletal maturation. While unsupplemented children showed increases in skinfold thic...

Sex differences in fetal growth responses to maternal height and weight

Sex differences in fetal growth have been reported, but how this happens remains to be described. It is unknown if fetal growth rates, a reflection of genetic and environmental factors, express sexually dimorphic sensitivity to the mother herself. This analysis investigated homogeneity of male and female growth responses to maternal height and weight. The study sample included 3,495 uncomplicated singleton pregnancies followed longitudinally. Analytic models regressed fetal and neonatal weight on tertiles of maternal height and weight, and modification by sex was investigated (n = 1,814 males, n = 1,681 females) with birth gestational age, maternal parity, and smoking as covariates. Sex modified the effects of maternal height and weight on fetal growth rates and birth weight. Among boys, tallest maternal height influenced fetal weight growth before 18 gestational weeks of age (P = 0.006), and prepregnancy maternal weight and body mass index subsequently had influence (P < 0.001); this was not found among girls. Additionally, interaction terms between sex, maternal height, and maternal weight identified that males were more sensitive to maternal weight among shorter mothers (P = 0.003) and more responsive to maternal height among lighter mothers (P ≤ 0.03), compared to females. Likewise, neonatal birth weight dimorphism varied by maternal phenotype. A male advantage of 60 g occurred among neonates of the shortest and lightest mothers (P = 0.08), compared to 150 and 191 g among short and heavy mothers, and tall and light‐weight mothers, respectively (P = 0.01). Sex differences in response to maternal size are under‐appreciated sources of variation in fetal growth studies and may reflect differential growth strategies. Am. J. Hum. Biol., 2010.

Problems in the aging of skeletal juveniles: Perspectives from maturation assessments of living children

We employ samples of children of known chronological age to demonstrate the significance of random and systematic effects on maturation in both dental and skeletal development. Differences between chronological age for dental age in young healthy Canadian children can be as much as 100% of the actual age of the children. For skeletal development by reference to Greulich-Pyle standards, three samples of known-age children from Mexico document parallel effects: 1) 183 six-year-old children have skeletal-based ages with a 95% confidence interval of 4-8 years; 2) 80% of 217 4.0-4.5-year-old children are underaged by 1-3 years; and 3) 130 children of skeletal age between 39 and 44 months are actually between 4 and 7.4 chronological years of age. The Mexican samples are drawn from a population living under conditions of environmental stress with chronic mild to moderate protein-energy malnutrition and moderate to high levels of infectious disease. These children may parallel those from the past, whose remains are studied by skeletal biologists or paleoanthropologists. Our findings reinforce concerns expressed in extant studies regarding the accuracy of age-at-death reconstructions.

A case study of daily growth during adolescence: a single spurt or changes in the dynamics of saltatory growth?

Standing height of one adolescent male was measured daily between the ages of 12.83 and 13.95 years on 328 days out of 389 consecutive days according to standard techniques for maximal stature measurement. The serial growth data were analysed by a modification of techniques developed to identify patterns in serial hormone data. The entire growth in height during this interval occurred during 12 non-periodic saltatory episodes with amplitude of 0.92 +/- 0.09 cm (SEM) in < or = 24 h separated by 3-100 days of no significant growth. The proposition that adolescent growth is characterized by a change in the dynamics of growth saltus amplitude and/or frequency is suggested.

Further observations on diurnal variation in standing height

A total of 328 daily assessments of standing height were made on one boy between the ages of 12.83 and 13.95 years; 292 of these were replicates to establish reliability of measurement. On 300 days, measurements were taken in the morning within 1/2 h of rising (which varied between 0700 and 1100 h) and repeated before bed on the same day, between 2100 and 2300 h. The standard error of measurement from 292 duplicate measurements was 0.12 cm. A mean of 0.98 +/- 0.2 cm decrease in stature occurred during the course of the day. A similar decrease was found on three occasions after 2-3 h naps.

Trajectories of body mass index amongst children who develop type 2 diabetes as adults.

Type 2 diabetes (T2D) is a heterogeneous disorder. The aim of this study was to examine the trajectories of childhood growth associated with T2D.

An example of variation and pattern in saltation and stasis growth dynamics

The serial data from two siblings, aged 6.6 and 7.5 years of age at the initiation of the study, measured each evening for total standing height during 365 days, are analysed by two methods to investigate the nature of the underlying growth pattern. The saltation and stasis model, designed to identify the presence of statistically significant pulses in sequential data, is compared for goodness-of-fit to first to sixth degree polynomial functions, used to investigate the presence of a slowly varying smooth continuous function in the data, and high order polynomials of the same degree of flexibility as the individuals saltation and stasis results. The saltation and stasis model is found to better-fit the experimental data than the slowly varying smooth continuous functions (p < 0.01 to 0.001). The timing characteristics of the saltation and stasis patterns are investigated and the temporal patterns are suggestive of a non-random, aperiodical deterministic system.

Early rapid growth, early birth: accelerated fetal growth and spontaneous late preterm birth.

The past two decades in the United States have seen a 24% rise in spontaneous late preterm delivery (34–36 weeks) of unknown etiology. This study tested the hypothesis that fetal growth was identical prior to spontaneous preterm (n = 221, median gestational age at birth 35.6 weeks) and term (n = 3706) birth among pregnancies followed longitudinally in Santiago, Chile. The hypothesis was not supported: Preterm‐delivered fetuses were significantly larger than their term‐delivered peers by mid‐second trimester in estimated fetal weight, head, limb, and abdominal dimensions, and they followed different growth trajectories. Piecewise regression assessed time‐specific differences in growth rates at 4‐week intervals from 16 weeks. Estimated fetal weight and abdominal circumference growth rates slowed at 20 weeks among the preterm‐delivered, only to match and/or exceed their term‐delivered peers at 24–28 weeks. After an abrupt growth rate decline at 28 weeks, fetuses delivered preterm did so at greater population‐specific sex and age‐adjusted birth weight percentiles than their peers from uncomplicated pregnancies (P < 0.01). Growth rates predicted birth timing: one standard score of estimated fetal weight increased the odds ratio for late preterm birth from 2.8 prior to 23 weeks, to 3.6 (95% confidence interval, 1.82–7.11, P < 0.05) between 23 and 27 weeks. After 27 weeks, increasing size was protective (OR: 0.56, 95% confidence interval, 0.38–0.82, P = 0.003). These data document, for the first time, a distinctive fetal growth pattern across gestation preceding spontaneous late preterm birth, identify the importance of mid‐gestation for alterations in fetal growth, and add perspective on human fetal biological variability. Am. J. Hum. Biol., 2009.