Early developmental conditioning of later health and disease: physiology or pathophysiology?

Extensive experimental animal studies and epidemiological observations have shown that environmental influences during early development affect the risk of later pathophysiological processes associated with chronic, especially noncommunicable, disease (NCD). This field is recognized as the developmental origins of health and disease (DOHaD). We discuss the extent to which DOHaD represents the result of the physiological processes of developmental plasticity, which may have potential adverse consequences in terms of NCD risk later, or whether it is the manifestation of pathophysiological processes acting in early life but only becoming apparent as disease later. We argue that the evidence suggests the former, through the operation of conditioning processes induced across the normal range of developmental environments, and we summarize current knowledge of the physiological processes involved. The adaptive pathway to later risk accords with current concepts in evolutionary developmental biology, especially those concerning parental effects. Outside the normal range, effects on development can result in nonadaptive processes, and we review their underlying mechanisms and consequences. New concepts concerning the underlying epigenetic and other mechanisms involved in both disruptive and nondisruptive pathways to disease are reviewed, including the evidence for transgenerational passage of risk from both maternal and paternal lines. These concepts have wider implications for understanding the causes and possible prevention of NCDs such as type 2 diabetes and cardiovascular disease, for broader social policy and for the increasing attention paid in public health to the lifecourse approach to NCD prevention.

Modifiable risk factors in the first 1000 days for subsequent risk of childhood overweight in an Asian cohort: significance of parental overweight status.

BACKGROUND/OBJECTIVE: Many studies have identified early-life risk factors for subsequent childhood overweight/obesity, but few have evaluated how they combine to influence risk of childhood overweight/obesity. We examined associations, individually and in combination, of potentially modifiable risk factors in the first 1000 days after conception with childhood adiposity and risk of overweight/obesity in an Asian cohort. METHODS: Six risk factors were examined: maternal pre-pregnancy overweight/obesity (body mass index (BMI) ⩾25 kg m-2), paternal overweight/obesity at 24 months post delivery, maternal excessive gestational weight gain, raised maternal fasting glucose during pregnancy (⩾5.1 mmol l-1), breastfeeding duration <4 months and early introduction of solid foods (<4 months). Associations between number of risk factors and adiposity measures (BMI, waist-to-height ratio (WHtR), sum of skinfolds (SSFs), fat mass index (FMI) and overweight/obesity) at 48 months were assessed using multivariable regression models. RESULTS: Of 858 children followed up at 48 months, 172 (19%) had none, 274 (32%) had 1, 244 (29%) had 2, 126 (15%) had 3 and 42 (5%) had ⩾4 risk factors. Adjusting for confounders, significant graded positive associations were observed between number of risk factors and adiposity outcomes at 48 months. Compared with children with no risk factors, those with four or more risk factors had s.d. unit increases of 0.78 (95% confidence interval 0.41-1.15) for BMI, 0.79 (0.41-1.16) for WHtR, 0.46 (0.06-0.83) for SSF and 0.67 (0.07-1.27) for FMI. The adjusted relative risk of overweight/obesity in children with four or more risk factors was 11.1(2.5-49.1) compared with children with no risk factors. Children exposed to maternal pre-pregnancy (11.8(9.8-13.8)%) or paternal overweight status (10.6(9.6-11.6)%) had the largest individual predicted probability of child overweight/obesity. CONCLUSIONS: Early-life risk factors added cumulatively to increase childhood adiposity and risk of overweight/obesity. Early-life and preconception intervention programmes may be more effective in preventing overweight/obesity if they concurrently address these multiple modifiable risk factors.

Which anthropometric measures best reflect neonatal adiposity?

BACKGROUND: Studying the determinants and the long-term consequences of fetal adipose accretion requires accurate assessment of neonatal body composition. In large epidemiological studies, in-depth body composition measurement methods are usually not feasible for cost and logistical reasons, and there is a need to identify anthropometric measures that adequately reflect neonatal adiposity. METHODS: In a multiethnic Asian mother-offspring cohort in Singapore, anthropometric measures (weight, length, abdominal circumference, skinfold thicknesses) were measured using standardized protocols in newborn infants, and anthropometric indices (weight/length, weight/length2 (body mass index, BMI), weight/length3 (ponderal index, PI)) derived. Neonatal total adiposity was measured using air displacement plethysmography (ADP) and abdominal adiposity using magnetic resonance imaging (MRI). Correlations of the anthropometric measures with ADP- and MRI-based adiposity were assessed using Pearson's correlation coefficients (rp), including in subsamples stratified by sex and ethnicity. RESULTS: Study neonates (n=251) had a mean (s.d.) age of 10.2 (2.5) days. Correlations between ADP-based fat mass (ADPFM) and anthropometric measures were moderate (rp range: 0.44-0.67), with the strongest being with weight/length, weight, BMI and sum of skinfolds (rp=0.67, 0.66, 0.62, 0.62, respectively, all P<0.01). All anthropometric measures except skinfold thicknesses correlated more strongly with ADP-based fat-free mass than ADPFM, indicating that skinfold measures may have more discriminative power in terms of neonatal total body adiposity. For MRI-based measures, weight and weight/length consistently showed strong positive correlations (rp⩾0.7) with abdominal adipose tissue compartments. These correlations were consistent in boys and girls, across different ethnic groups, and when conventional determinants of neonatal adiposity were adjusted for potential confounding. Abdominal circumference was not strongly associated with ADPFM or abdominal fat mass. CONCLUSIONS: Simple anthropometric measures (weight and weight/length) correlated strongly with neonatal adiposity, with some evidence for greater discriminative power for skinfold measures. These simple measures could be of value in large epidemiological studies.

Postnatal height and adiposity gain, childhood blood pressure and prehypertension risk in an Asian birth cohort.

OBJECTIVE: There have been hypotheses that early life adiposity gain may influence blood pressure (BP) later in life. We examined associations between timing of height, body mass index (BMI) and adiposity gains in early life with BP at 48 months in an Asian pregnancy-birth cohort. METHODS: In 719 children, velocities for height, BMI and abdominal circumference (AC) were calculated at five intervals [0-3, 3-12, 12-24, 24-36 and 36-48 months]. Triceps (TS) and subscapular skinfold (SS) velocities were calculated between 0-18, 18-36 and 36-48 months. Systolic (SBP) and diastolic blood pressure (DBP) was measured at 48 months. Growth velocities at later periods were adjusted for growth velocities in preceding intervals, as well as measurements at birth. RESULTS: After adjusting for confounders and child height at BP measurement, each unit z-score gain in BMI, AC, TS and SS velocities at 36-48 months were associated with 2.3 (95% CI:1.6, 3.1), 2.1 (1.3, 2.8), 1.4 (0.6, 2.2) and 1.8 (1, 2.6) mmHg higher SBP respectively, and 0.9 (0.4, 1.4), 0.9 (0.4, 1.3), 0.6 (0.1, 1.1) and 0.8 (0.3, 1.3) mmHg higher DBP respectively. BMI and adiposity velocities (AC, TS or SS) at various intervals in the first 36 months however, were not associated with BP. Faster BMI, AC, TS and SS velocities, but not height, at 36-48 months were associated with 0.22 (0.15, 0.29), 0.17 (0.10, 0.24), 0.11 (0.04, 0.19) and 0.15 (0.08, 0.23) units higher SBP z-score respectively, and OR=1.46 (95% CI: 1.13-1.90), 1.49 (1.17-1.92), 1.45 (1.09-1.92) and 1.43 (1.09, 1.88) times higher risk of prehypertension/hypertension respectively at 48 months. CONCLUSIONS: Our results indicated that faster BMI and adiposity (AC, TS or SS) velocities only at the preceding interval before 48 months (36-48 months), but not at earlier intervals in the first 36 months, are predictive of BP and prehypertension/hypertension at 48 months.

Maternal hyperglycemia in singleton pregnancies conceived by IVF may be modified by first-trimester BMI.

STUDY QUESTION: Does IVF independently increase the risk of gestational diabetes mellitus (GDM) and is this increase in risk modified by maternal body mass index? SUMMARY ANSWER: IVF appears to be an independent risk factor for GDM and elevated blood glucose levels in overweight women (BMI > 25 kg/m2). WHAT IS KNOWN ALREADY: IVF has been associated with increased risk of GDM, but most previous studies did not adequately assess confounding or effect modification by other risk factors. STUDY DESIGN, SIZE, DURATION: Cross-sectional study using data from 1089 women with singleton pregnancies who participated in a Singaporean birth cohort study (GUSTO) and received a 75 g oral glucose tolerance test (OGTT) at 26-28 weeks gestation. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 1089 women (n = 1013 conceived spontaneously, n = 76 conceived through IVF) with singleton pregnancies received a 75 g OGTT at 26-28 weeks gestation. Fasting and 2 h postprandial blood glucose levels were assayed. World Health Organization criteria (1999) standard criteria were used to classify GDM: ≥7.0 mmol/L for fasting and/or ≥7.8 mmol/L for 2-h postprandial plasma glucose levels, which was the clinical guideline in use during the study. MAIN RESULTS AND THE ROLE OF CHANCE: IVF pregnancies had nearly double the odds of GDM (OR = 1.83, 95% CI: 1.03-3.26) and elevated fasting (mean difference = 0.12 mmol/L, 95% CI: 0.00-0.24) and OGTT 2-h blood glucose levels (mean difference = 0.64 mmol/L, 95% CI: 0.27-1.01), after adjusting for commonly recognized risk factors for GDM. After stratification by first-trimester BMI, these increased risks of GDM (OR = 3.54, 95% CI: 1.44-8.72) and elevated fasting (mean difference = 0.39 mmol/L, 95% CI: 0.13-0.65) and 2-h blood (mean difference = 1.24 mmol/L, 95% CI: 0.56-1.91) glucose levels were significant only in the IVF group who is also overweight or obese (BMI > 25 kg/m2). LIMITATIONS REASONS FOR CAUTION: One limitation of our study is the absence of a 1 h post-OGTT plasma glucose sample, as we were using the 1999 WHO diagnostic criteria (the clinical guideline in Singapore) at the time of our study, instead of the revised 2013 WHO diagnostic criteria. Our cohort may not be representative of the general Singapore obstetric population, although participants were recruited from the two largest maternity hospitals in the country and include both private and subsidized patients. WIDER IMPLICATIONS OF THE FINDINGS: IVF appears to be an independent risk factor for GDM and elevated blood glucose levels in overweight women. Our findings reinforce the need to advise overweight or obese women contemplating IVF to lose weight before the procedure to reduce their risk of GDM and hyperglycemia-related adverse outcomes arising therefrom. In settings where universal GDM screening is not routine, overweight or obese women who conceive by IVF should be screened. STUDY FUNDING/COMPETING INTEREST(S): This research was supported by the Singapore National Research Foundation under its Translational and Clinical Research (TCR) Flagship Program and administered by the Singapore Ministry of Health's National Medical Research Council (NMRC), Singapore (NMRC/TCR/004-NUS/2008; NMRC/TCR/012-NUHS/2014). Additional funding was provided by the Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR). K.M.G. and Y.S.C. have received lecture fees from Nestle Nutrition Institute and Danone, respectively. K.M.G., Y.S.C. and S.Y.C. are part of an academic consortium that has received research funding from Abbott Nutrition, Nestec and Danone. The other authors have nothing to disclose. The other authors have nothing to disclose. TRIAL REGISTRATION NUMBER: N/A.

Tobacco smoke exposure and respiratory morbidity in young children.

OBJECTIVE: Secondhand smoke exposure is a potentially preventable cause of significant respiratory morbidity in young children. Our study aimed to quantify respiratory morbidity in young children exposed to secondhand smoke to identify potentially modifiable factors. MATERIALS AND METHODS: This study was embedded in a prospective birth cohort study of pregnant women and their children from fetal life onwards in Singapore (Growing Up in Singapore Towards healthy Outcomes, or GUSTO). Data on prenatal, antenatal and postnatal active and secondhand tobacco smoke exposure were obtained by an investigator-administered questionnaire for the periods before pregnancy, at 26-28 weeks' gestation and 24 months after delivery. Data on respiratory morbidity (wheezing episodes, croupy cough, nebuliser use, snoring) and other morbidity (fever, hospitalisation, ear infection) of the child was collected at week 3 and at months 3, 6, 9, 12, 15, 18 and 24 after delivery. Information on parental atopy and potential confounders such as socioeconomic status and maternal educational level were also obtained. Statistical analysis of the data was performed to quantify any significant differences in incidence of respiratory morbidity in children exposed to tobacco smoke in utero and postdelivery, compared with those in smoke-free environments. RESULTS: Women who smoked regularly prior to pregnancy comprised 12.5% (n=155) of the study population; this number fell to 2.3% (n=29) during pregnancy. Mothers exposed to secondhand smoke in the household before pregnancy comprised 35.7% of the study population (n=441) and 31.5% (n=389) were exposed during pregnancy. Postnatally, the prevalence of secondhand tobacco smoke exposure from birth to 2 years of age was 29% (n=359). Participants of Malay ethnicity (p<0.001), mothers with no or primary level education (p<0.001) and mothers with low socioeconomic status (p<0.001) had the highest exposure to tobacco smoke. Offspring secondhand smoke exposure at home by 12 months and by 24 months of age was associated with an increase in hospital admissions due to respiratory disease (RR 1.89, 95% CI 1.02 to 3.50, p=0.04 by 12 months and RR 1.64, 95% CI 1.05 to 2.55, p=0.03 by 24 months) as well as all-cause hospitalisation (RR 1.57, 95% CI 1.14 to 2.17, p=0.01 by 12 months and RR 1.49, 95% CI 1.17 to 1.90, p=0.001 by 24 months), adjusting for parental atopy and child atopic dermatitis. Participants exposed to secondhand smoke by 12 months postdelivery had a significantly increased risk of having at least one wheezing episode (RR 1.71, 95% CI 1.38 to 2.11, p<0.001). CONCLUSIONS: Secondhand smoke exposure during the prenatal and postnatal periods is associated with increased respiratory morbidity in children. Opportunistic screening and targeted smoking cessation counselling for parents at child hospital admissions and well-child outpatient visits, as well as preconception smoking cessation counselling for future pregnancies, may be beneficial to protect the child from negative health impacts.

Transgenerational effects of prenatal exposure to the 1944-45 Dutch famine.

OBJECTIVE: We previously showed that maternal under-nutrition during gestation is associated with increased metabolic and cardiovascular disease in the offspring. Also, we found increased neonatal adiposity among the grandchildren of women who had been undernourished during pregnancy. In the present study we investigated whether these transgenerational effects have led to altered body composition and poorer health in adulthood in the grandchildren. DESIGN: Historical cohort study. SETTING: Web-based questionnaire. POPULATION: The adult offspring (F2) of a cohort of men and women (F1) born around the time of the 1944-45 Dutch famine. METHODS: We approached the F2 adults through their parents. Participating F2 adults (n = 360, mean age 37 years) completed an online questionnaire. MAIN OUTCOME MEASURES: Weight, body mass index (BMI), and health in F2 adults, according to F1 prenatal famine exposure. RESULTS: Adult offspring (F2) of prenatally exposed F1 fathers had higher weights and BMIs than offspring of prenatally unexposed F1 fathers (+4.9 kg, P = 0.03; +1.6 kg/m(2), P = 0.006). No such effect was found for the F2 offspring of prenatally exposed F1 mothers. We observed no differences in adult health between the F2 generation groups. CONCLUSIONS: Offspring of prenatally undernourished fathers, but not mothers, were heavier and more obese than offspring of fathers and mothers who had not been undernourished prenatally. We found no evidence of transgenerational effects of grandmaternal under-nutrition during gestation on the health of this relatively young group, but the increased adiposity in the offspring of prenatally undernourished fathers may lead to increased chronic disease rates in the future.

Inhibition of myostatin protects against diet-induced obesity by enhancing fatty acid oxidation and promoting a brown adipose phenotype in mice.

AIMS/HYPOTHESIS: Although myostatin-null (Mstn (-/-)) mice fail to accumulate fat in adipose tissue when fed a high-fat diet (HFD), little is known about the molecular mechanism(s) behind this phenomenon. We therefore sought to identify the signalling pathways through which myostatin regulates accumulation and/or utilisation of fat. METHODS: Wild-type, Mstn (-/-) and wild-type mice treated with soluble activin type IIB receptor (sActRIIB) were fed a control chow diet or an HFD for 12 weeks. Changes in gene expression were measured by microarray and quantitative PCR. Histological changes in white adipose tissue were assessed together with peripheral tissue fatty acid oxidation and changes in circulating hormones following HFD feeding. RESULTS: Our results demonstrate that inactivation of myostatin results in reduced fat accumulation in mice on an HFD. Molecular analysis revealed that metabolic benefits, due to lack of myostatin, are mediated through at least two independent mechanisms. First, lack of myostatin increased fatty acid oxidation in peripheral tissues through induction of enzymes involved in lipolysis and in fatty acid oxidation in mitochondria. Second, inactivation of myostatin also enhanced brown adipose formation in white adipose tissue of Mstn (-/-) mice. Consistent with the above, treatment of HFD-fed wild-type mice with the myostatin antagonist, sActRIIB, reduced the obesity phenotype. CONCLUSIONS/INTERPRETATION: We conclude that absence of myostatin results in enhanced peripheral tissue fatty acid oxidation and increased thermogenesis, culminating in increased fat utilisation and reduced adipose tissue mass. Taken together, our data suggest that anti-myostatin therapeutics could be beneficial in alleviating obesity.

Myostatin-deficient mice exhibit reduced insulin resistance through activating the AMP-activated protein kinase signalling pathway.

AIMS/HYPOTHESIS: Myostatin-null mice (Mstn(-/-)) have reduced body fat and increased tolerance to glucose. To date the molecular mechanisms through which myostatin regulates body fat content and insulin sensitivity are not known. Therefore, the aim of the current study was to identify signalling pathways through which myostatin regulates insulin sensitivity. METHODS: Wild-type (WT) mice and Mstn(-/-) mice were fed either a control chow diet or a high fat diet (HFD) for 12 weeks. Glucose tolerance testing and insulin stimulated glucose uptake by M. extensor digitorum longus (EDL) were used as variables to determine insulin sensitivity. Quantitative PCR, Western blotting and enzyme assays were used to monitor AMP-activated protein kinase (AMPK) levels and activity. RESULTS: Mstn(-/-) mice exhibited reduced fat accumulation and peripheral insulin resistance when compared with WT mice, even when they were fed an HFD. Furthermore, treatment with a myostatin antagonist also increased insulin sensitivity during HFD. Consistent with increased insulin sensitivity, we also detected elevated levels of GLUT4, AKT, p-AKT and insulin receptor substrate-1 in Mstn(-/-) muscles. Molecular analysis showed that there is increased expression and activity of AMPK in Mstn(-/-) muscles. Furthermore, we also observed an increase in the AMPK downstream target genes, Sirt1 and Pgc-1α (also known as Ppargc1a), in skeletal muscle of Mstn(-/-) mice. CONCLUSIONS/INTERPRETATION: We conclude that myostatin inactivation leads to increased AMPK levels and activity resulting in increased insulin sensitivity of skeletal muscle. We propose that, by regulating AMPK in skeletal muscle and adipose tissues, myostatin plays a major role in regulating insulin signalling.

Income disparity in school readiness and the mediating role of perinatal maternal mental health: a longitudinal birth cohort study.

AIMS: There is compelling evidence for gradient effects of household income on school readiness. Potential mechanisms are described, yet the growth curve trajectory of maternal mental health in a child's early life has not been thoroughly investigated. We aimed to examine the relationships between household incomes, maternal mental health trajectories from antenatal to the postnatal period, and school readiness. METHODS: Prospective data from 505 mother-child dyads in a birth cohort in Singapore were used, including household income, repeated measures of maternal mental health from pregnancy to 2-years postpartum, and a range of child behavioural, socio-emotional and cognitive outcomes from 2 to 6 years of age. Antenatal mental health and its trajectory were tested as mediators in the latent growth curve models. RESULTS: Household income was a robust predictor of antenatal maternal mental health and all child outcomes. Between children from the bottom and top household income quartiles, four dimensions of school readiness skills differed by a range of 0.52 (95% Cl: 0.23, 0.67) to 1.21 s.d. (95% CI: 1.02, 1.40). Thirty-eight percent of pregnant mothers in this cohort were found to have perinatal depressive and anxiety symptoms in the subclinical and clinical ranges. Poorer school readiness skills were found in children of these mothers when compared to those of mothers with little or no symptoms. After adjustment of unmeasured confounding on the indirect effect, antenatal maternal mental health provided a robust mediating path between household income and multiple school readiness outcomes (χ2 126.05, df 63, p < 0.001; RMSEA = 0.031, CFI = 0.980, SRMR = 0.034). CONCLUSIONS: Pregnant mothers with mental health symptoms, particularly those from economically-challenged households, are potential targets for intervention to level the playing field of their children.

20-kDa placental hGH-V has diminished diabetogenic and lactogenic activities compared with 22-kDa hGH-N while retaining antilipogenic activity.

Placental human growth hormone-variant (hGH-V) and pituitary human growth hormone-N (hGH-N) are of identical size (22 kDa) but differ in 13 residues scattered throughout the protein. Several isoforms of GH are produced by the hGH-N and hGH-V genes including a 20-kDa hGH-V resulting from a 45-bp deletion caused by the use of an alternative acceptor site within exon 3. To date, the biological properties of the 20-kDa GH-V have not been characterized in vivo. Using young male Wistar rats fed either chow or a high-fat (HF) diet for 4 wk postweaning, we investigated the effect of 7 days treatment with either 22-kDa hGH-N, 20-kDa hGH-V (5 ug x g(-1) x day(-1) sc), or vehicle on body composition and endocrine and metabolic profiles. Total body growth (absolute weight gain and linear growth trajectory) in the 20-kDa hGH-V-treated animals was intermediary between that of control and hGH-N-treated animals. Both 22-kDa hGH-N and 20-kDa hGH-V significantly reduced total body fat mass compared with control animals, and there were no differences between the GH isoforms in anti-lipogenic activity in animals fed the HF diet. Fasting plasma insulin and C peptide were significantly increased in animals on the HF diet and further increased by hGH-N but were unchanged in 20-kDa hGH-V-treated animals compared with saline-treated controls. Plasma volume as assessed by hematocrit was increased in hGH-N-treated animals but was unchanged in 20-kDa hGH-V-treated animals compared with controls. Furthermore, 20-kDa hGH-V had reduced lactogenic (prolactin receptor mediated) activity characteristic of hGH-N as tested in vitro compared with the 20-kDa hGH-N and 22-kDa hGH-N variants. In summary, placental 20-kDa hGH-V retains some of the growth-promoting and all antilipogenic activities of pituitary 22-kDa hGH-N but has diminished diabetogenic and lactogenic properties compared with the native 22-kDa hGH-N.

The insulin-like growth factor system and its pleiotropic functions in brain.

In recent years, much interest has been devoted to defining the role of the IGF system in the nervous system. The ubiquitous IGFs, their cell membrane receptors, and their carrier binding proteins, the IGFBPs, are expressed early in the development of the nervous system and are therefore considered to play a key role in these processes. In vitro studies have demonstrated that the IGF system promotes differentiation and proliferation and sustains survival, preventing apoptosis of neuronal and brain derived cells. Furthermore, studies of transgenic mice overexpressing components of the IGF system or mice with disruptions of the same genes have clearly shown that the IGF system plays a key role in vivo.

DOHaD - the challenge of translating the science to policy.

The DOHaD Society has passed its 10th birthday, so it seems an appropriate time to reflect on what has been achieved and the Society's aspirations. At the 10th International Congress in Rotterdam in November 2017, Peter Gluckman (the Society's first President) delivered a plenary lecture entitled 'DOHaD - addressing the science-policy nexus: a reality check'; in opening the Congress, Mark Hanson (second, and outgoing President) not only highlighted the success of the Society but also the challenges it now faces in achieving impact for its work in the global health arena, that is beyond the research agenda; and in assuming the role of third President, Lucilla Poston highlighted the need for the Society to grasp opportunities to change healthcare policy, while persevering with basic research and well-planned intervention studies. In this review we summarize the points made in these three presentations and issue a call to action to the membership to take up the challenge of taking the Society's work to the next level of translating science to policy.

HOXA1-stimulated oncogenicity is mediated by selective upregulation of components of the p44/42 MAP kinase pathway in human mammary carcinoma cells.

Expression of homeobox A1 (HOXA1) results in oncogenic transformation of immortalized human mammary epithelial cells with aggressive tumor formation in vivo. However, the mechanisms by which HOXA1 mediates oncogenic transformation is not well defined. To identify molecules that could potentially be involved in HOXA1-mediated oncogenic transformation, microarray analysis was utilized to characterize and compare the gene expression pattern in response to forced expression or depletion of HOXA1 in human mammary carcinoma cells. Gene expression profiling identified that genes involved in the p44/42 mitogen-activated protein (MAP) kinase activation pathway (GRB2, MAP kinase kinase (MEK1) and SDFR1) or p44/42 MAP kinase-regulated genes (IER3, EPAS1, PCNA and catalase) are downstream expression targets of HOXA1. Forced expression of HOXA1 increased GRB2 and MEK1 mRNA and protein expression and increased p44/42 MAP kinase phosphorylation, activity and Elk-1-mediated transcription. Use of a MEK1 inhibitor demonstrated that increased p44/42 MAP kinase activity is required for the HOXA1-mediated increase in cell proliferation, survival, oncogenicity and oncogenic transformation. Thus, modulation of the p44/42 MAP kinase pathway is one mechanism by which HOXA1 mediates oncogenic transformation of the human mammary epithelial cell.

Developmental and epigenetic pathways to obesity: an evolutionary-developmental perspective.

Although variation in individual lifestyle and genotype are important factors in explaining individual variation in the risk of developing obesity in an obesogenic environment, there is growing evidence that developmentally plastic processes also contribute. These effects are mediated at least in part through epigenetic processes. These developmental pathways do not directly cause obesity but rather alter the risk of an individual developing obesity later in life. At least two classes of developmental pathway are involved. The mismatch pathway involves the evolved adaptive responses of the developing organism to anticipated future adverse environments, which have maladaptive consequences if the environment is mismatched to that predicted. This pathway can be cued by prenatal undernutrition or stresses that lead the organism to forecast an adverse future environment and change its developmental trajectory accordingly. As a result, individuals develop with central and peripheral changes that increase their sensitivity to an obesogenic environment. It provides a model for how obesity emerges in populations in rapid transition, but also operates in developed countries. There is growing experimental evidence that this pathway can be manipulated by, for example, postnatal leptin exposure. Secondly, maternal diabetes, maternal obesity and infant overfeeding are associated with a greater risk of later obesity. Early life offers a potential point for preventative intervention.

Body composition measurement in young children using quantitative magnetic resonance: a comparison with air displacement plethysmography.

BACKGROUND: Quantitative magnetic resonance (QMR) has been increasingly used to measure human body composition, but its use and validation in children is limited. OBJECTIVE: We compared body composition measurement by QMR and air displacement plethysmography (ADP) in preschool children from Singapore's multi-ethnic Asian population (n = 152; mean ± SD age: 5.0 ± 0.1 years). METHODS: Agreements between QMR-based and ADP-based fat mass and fat mass index (FMI) were assessed using intraclass correlation coefficient (ICC), reduced major axis regression and Bland-Altman plot analyses. Analyses were stratified for the child's sex. RESULTS: Substantial agreement was observed between QMR-based and ADP-based fat mass (ICC: 0.85) and FMI (ICC: 0.82). Reduced major axis regression analysis suggested that QMR measurements were generally lower than ADP measurements. Bland-Altman analysis similarly revealed that QMR-based fat mass were (mean difference [95% limits of agreement]) -0.5 (-2.1 to +1.1) kg lower than ADP-based fat mass and QMR-based FMI were -0.4 (-1.8 to +0.9) kg/m2 lower than ADP-based FMI. Stratification by offspring sex revealed better agreement of QMR and ADP measurements in girls than in boys. CONCLUSIONS: QMR-based fat mass and FMI showed substantial agreement with, but was generally lower than, ADP-based measures in young Asian children.

Insulin-like growth factor-1 is a potent neuronal rescue agent after hypoxic-ischemic injury in fetal lambs.

This study was designed to determine the potential of IGF-1 as a neuronal rescue agent after cerebral ischemia. Unanesthetized late gestation fetal sheep were subjected to 30-min cerebral ischemia by inflation of carotid artery occluder cuffs. 2 h later either 0.1 microgram rhIGF-1, 1 microgram rhIGF-1, 10 micrograms rhIGF-1, or vehicle was infused into a lateral cerebral ventricle over 1 h. Histologic outcome was assessed 5 d later. Overall neuronal loss was reduced with 0.1 microgram (P < 0.05) and 1 microgram (P < 0.002) rhIGF-1, but treatment with 10 micrograms was not effective. With 1 microgram rhIGF-1 neuronal loss scores were significantly lower in brain regions examined including cortex, hippocampus, and striatum, whereas with 0.1 microgram rhIGF-1 the parietal cortex and thalamus were not improved and the improvement seen in other regions was less than with 1 microgram rhIGF-1. Treatment with 1 microgram rhIGF-1 also delayed the onset of seizures and reduced their incidence. Moreover, the secondary phase of cytotoxic edema was reduced and delayed in onset. We conclude that low dose rhIGF-1 therapy promotes neuronal rescue after cerebral hypoxic-ischemic injury in utero, but the effect is dose dependent. Importantly, rhIGF-1 is effective and nontoxic when administered 2 h after the hypoxic ischemic insult. This distinguishes IGF-1 from most other neuroprotective therapies and suggests clinical application may be possible.

The effects of infusion of insulinlike growth factor (IGF) I, IGF-II, and insulin on glucose and protein metabolism in fasted lambs.

In vivo effects of 300-min infusions of recombinant insulinlike growth factor I (IGF-I) and IGF-II on glucose and protein metabolism have been investigated in awake, fasted lambs. Two doses of recombinant human (rh) IGF-I were infused: 6.7 nmol/kg.h, which induced hypoglycemia, and 2.0 nmol/kg.h, which did not. The effects were compared with an insulin infusion (0.17 nmol/kg.h) that had the same hypoglycemic potential as the high dose rhIGF-I infusion. rhIGF-II was infused at a rate of 6.7 nmol/kg.h. Primed constant infusions of isotopically labeled glucose, urea and leucine tracers were used to determine glucose and protein kinetics. rhIGF-I lowered blood glucose by increasing the rate of glucose clearance (P less than 0.01), in contrast to insulin, which both increased clearance and reduced glucose production. Net protein loss was reduced after infusion of low and high dose rhIGF-I and insulin by 11% (P less than 0.05), 15% (P less than 0.01), and 12% (P less than 0.05), respectively. rhIGF-II infusion did not alter the rate of net protein loss. In contrast to insulin, high dose rhIGF-I infusion increased the rate of protein synthesis in skeletal (P less than 0.05) and cardiac muscle (P less than 0.01) and in hepatic tissue (P less than 0.05). We conclude that (a) protein metabolism is more sensitive than glucose metabolism to rhIGF-I infusion, as protein loss was reduced by an rhIGF-I infusion that did not alter glucose kinetics; (b) protein synthesis is increased by rhIGF-I infusion but not by insulin infusion; and (c) rhIGF-II is a less effective anabolic agent than rhIGF-I. We speculate that the effects of rhIGF-I on protein metabolism are not mediated by insulin receptors.

Dramatic neuronal rescue with prolonged selective head cooling after ischemia in fetal lambs.

Hypothermia has been proposed as a neuroprotective strategy. However, short-term cooling after hypoxia-ischemia is effective only if started immediately during resuscitation. The aim of this study was to determine whether prolonged head cooling, delayed into the late postinsult period, improves outcome from severe ischemia. Unanesthetized near term fetal sheep were subject to 30 min of cerebral ischemia. 90 min later they were randomized to either cooling (n = 9) or sham cooling (n = 7) for 72 h. Intrauterine cooling was induced by a coil around the fetal head, leading initially to a fall in extradural temperature of 5-10 degrees C, and a fall in esophageal temperature of 1.5-3 degrees C. Cooling was associated with mild transient systemic metabolic effects, but not with hypotension or altered fetal heart rate. Cerebral cooling reduced secondary cortical cytotoxic edema (P < 0.001). After 5 d of recovery there was greater residual electroencephalogram activity (-5.2+/-1.6 vs. -15.5+/-1.5 dB, P < 0.001) and a dramatic reduction in the extent of cortical infarction and neuronal loss in all regions assessed (e.g., 40 vs. 99% in the parasagittal cortex, P < 0.001). Selective head cooling, maintained throughout the secondary phase of injury, is noninvasive and safe and shows potential for improving neonatal outcome after perinatal asphyxia.