Betamethasone-exposed preterm birth does not impair insulin action in adult sheep

Preterm birth is associated with increased risk of type 2 diabetes (T2D) in adulthood; however, the underlying mechanisms are poorly understood. We therefore investigated the effect of preterm birth at ~0.9 of term after antenatal maternal betamethasone on insulin sensitivity, secretion and key determinants in adulthood, in a clinically relevant animal model. Glucose tolerance and insulin secretion (intravenous glucose tolerance test) and whole-body insulin sensitivity (hyperinsulinaemic euglycaemic clamp) were measured and tissue collected in young adult sheep (14 months old) after epostane-induced preterm (9M, 7F) or term delivery (11M, 6F). Glucose tolerance and disposition, insulin secretion, β-cell mass and insulin sensitivity did not differ between term and preterm sheep. Hepatic PRKAG2 expression was greater in preterm than in term males (P = 0.028), but did not differ between preterm and term females. In skeletal muscle, SLC2A4 (P = 0.019), PRKAA2 (P = 0.021) and PRKAG2 (P = 0.049) expression was greater in preterm than in term overall and in males, while INSR (P = 0.047) and AKT2 (P = 0.043) expression was greater in preterm than in term males only. Hepatic PRKAG2 expression correlated positively with whole-body insulin sensitivity in males only. Thus, preterm birth at 0.9 of term after betamethasone does not impair insulin sensitivity or secretion in adult sheep, and has sex-specific effects on gene expression of the insulin signalling pathway. Hence, the increased risk of T2D in preterm humans may be due to factors that initiate preterm delivery or in early neonatal exposures, rather than preterm birth per se.

The effect of antenatal lifestyle advice for women who are overweight or obese on secondary measures of neonatal body composition: the LIMIT randomised trial

OBJECTIVE

To evaluate the effect of providing antenatal dietary and lifestyle advice on neonatal anthropometry, and to determine the inter-observer variability in obtaining anthropometric measurements.

DESIGN

Randomised controlled trial.

SETTING

Public maternity hospitals across metropolitan Adelaide, South Australia.

POPULATION

Pregnant women with a singleton gestation between 10(+0) and 20(+0) weeks, and body mass index (BMI) ≥25 kg/m(2).

METHODS

Women were randomised to either Lifestyle Advice (comprehensive dietary and lifestyle intervention over the course of pregnancy including dietary, exercise and behavioural strategies, delivered by a research dietician and research assistants) or continued Standard Care. Analyses were conducted using intention-to-treat principles.

MAIN OUTCOME MEASURES

Secondary outcome measures for the trial included assessment of infant body composition using body circumference and skinfold thickness measurements (SFTM), percentage body fat, and bio-impedance analysis of fat-free mass.

RESULTS

Anthropometric measurements were obtained from 970 neonates (488 Lifestyle Advice Group, and 482 Standard Care Group). In 394 of these neonates (215 Lifestyle Advice Group, and 179 Standard Care Group) bio-impedance analysis was also obtained. There were no statistically significant differences identified between those neonates born to women receiving Lifestyle Advice and those receiving Standard Care, in terms of body circumference measures, SFTM, percentage body fat, fat mass, or fat-free mass. The intra-class correlation coefficient for SFTM was moderate to excellent (0.55-0.88).

CONCLUSIONS

Among neonates born to women who are overweight or obese, anthropometric measures of body composition were not modified by an antenatal dietary and lifestyle intervention.

Maternal body size prior to pregnancy, gestational diabetes and weight gain: associations with insulin resistance in children at 9-10 years

AIMS

To investigate whether maternal body size pre-pregnancy, gestational diabetes and weight gain are independently associated with subsequent insulin resistance in children; and to examine the potential mediating role of child's body size in any associations.

METHODS

At 9-10 years, 443 children took part in a follow-up of a prospective cohort. Of those, 163 children elected to provide a fasting blood sample and child insulin resistance was estimated by homeostasis model assessment. Generalized linear models with log link function and Gaussian family were used to assess associations with antenatal exposures. Potential confounders were considered as well as the role of the child's size.

RESULTS

Prior to pregnancy, 23% of mothers were overweight and another 17% obese. All women were screened for gestational diabetes, with 6% diagnosed. On average, women gained an estimated 14 kg during pregnancy. Gestational diabetes was positively associated with child insulin resistance. In addition, maternal pre-pregnancy body mass index (BMI) was associated with child insulin resistance in a non-linear manner: a positive, progressive association was observed until BMI of 30 kg/m² was reached, but not thereafter. Estimated gestational weight gain was not associated with child insulin resistance. These findings were not accounted for by size of the child at birth or at 9-10 years.

CONCLUSIONS

Maternal body size prior to pregnancy is positively associated with increases in child insulin resistance, at least until the 'obese' category is reached. This is independent of gestational diabetes and not mediated by body size of the child, suggesting genetic and/or developmental programming origins.

Myogenesis in small and large ovine fetuses at three stages of pregnancy

Perturbations of the prenatal environment may influence fetal muscle development. This study investigated muscle cellularity and mRNA abundance of myogenic genes in fetal sheep divergent in their patterns of growth. Muscle samples were obtained from small and large fetuses on Days 50, 92 and 133 of pregnancy. Number of myofibres in the semitendinosus muscle increased between Day 92 and 133 of pregnancy, but did not differ between small and large fetuses at either stage of pregnancy. The semitendinosus of small fetuses had smaller cross-sectional areas of myofibres than did those of their large counterparts on Day 133 of pregnancy. The semitendinosus of small fetuses also had lower DNA concentration on Day 92 and lower protein concentration on Day 133 than did those of large fetuses. The mRNA levels of the myogenic regulatory factors (MRFs), myostatin, the insulin-like growth factors and embryonic myosin in fetal muscles varied with the stage of development, but no differences occurred in response to divergent fetal growth. Myostatin mRNA was more abundant in the semitendinosus than in the supraspinatus muscle on Days 92 and 133, as were myogenic regulatory factors, myf-5, myf-6 and follistatin mRNA on Day 133. The results indicated that muscle growth but not the number of myofibres in fetal sheep is modified by restricted fetal growth, and that genes that regulate muscle development are affected by the stage of development in an anatomical muscle-specific manner.

Circulating IGF1 and IGF2 and SNP genotypes in men and pregnant and non-pregnant women

Circulating IGFs are important regulators of prenatal and postnatal growth, and of metabolism and pregnancy, and change with sex, age and pregnancy. Single-nucleotide polymorphisms (SNPs) in genes coding for these hormones associate with circulating abundance of IGF1 and IGF2 in non-pregnant adults and children, but whether this occurs in pregnancy is unknown. We therefore investigated associations of plasma IGF1 and IGF2 with age and genotype at candidate SNPs previously associated with circulating IGF1, IGF2 or methylation of the INS-IGF2-H19 locus in men (n=134), non-pregnant women (n=74) and women at 15 weeks of gestation (n=98). Plasma IGF1 concentrations decreased with age (P<0.001) and plasma IGF1 and IGF2 concentrations were lower in pregnant women than in non-pregnant women or men (each P<0.001). SNP genotypes in the INS-IGF2-H19 locus were associated with plasma IGF1 (IGF2 rs680, IGF2 rs1004446 and IGF2 rs3741204) and IGF2 (IGF2 rs1004446, IGF2 rs3741204 and H19 rs217727). In single SNP models, effects of IGF2 rs680 were similar between groups, with higher plasma IGF1 concentrations in individuals with the GG genotype when compared with GA (P=0.016), or combined GA and AA genotypes (P=0.003). SNPs in the IGF2 gene associated with IGF1 or IGF2 were in linkage disequilibrium, hence these associations could reflect other genotype variations within this region or be due to changes in INS-IGF2-H19 methylation previously associated with some of these variants. As IGF1 in early pregnancy promotes placental differentiation and function, lower IGF1 concentrations in pregnant women carrying IGF2 rs680 A alleles may affect placental development and/or risk of pregnancy complications.

Vitamin B12 and homocysteine status during pregnancy in the metformin in gestational diabetes trial: responses to maternal metformin compared with insulin treatment

AIM

The aim of the study is to compare the effects of metformin and insulin treatment for gestational diabetes mellitus (GDM) on vitamin B12 and homocysteine (Hcy) status.

METHODS

Women with GDM, who met criteria for insulin treatment, were randomly assigned to metformin (n = 89) or insulin (n = 91) in the Adelaide cohort of the metformin in gestational diabetes (MiG) trial. Fasting serum total vitamin B12 (TB12), holotranscobalamin (HoloTC), a marker of functional B12 status and plasma Hcy concentrations were measured at 20-34 weeks (at randomization) and 36 weeks gestation, then at 6-8 weeks postpartum.

RESULTS

Circulating TB12, HoloTC and Hcy were similar in both treatment groups at each time point. Women who were taking dietary folate supplements at randomization had higher serum TB12 and HoloTC at randomization than those not taking folate. Overall, serum TB12 fell more between randomization and 36 weeks gestation in the metformin group than in the insulin group (metformin: -19.7 ± 4.7 pmol/l, insulin: -6.4 ± 3.6 pmol/l, p = 0.004). The decrease in serum TB12 during treatment was greater with increasing treatment duration in metformin-treated (p < 0.001), but not in insulin-treated women.

CONCLUSIONS

Total, but not bioavailable, vitamin B12 stores were depleted during pregnancy to a greater extent in metformin-treated than in insulin-treated women with GDM, but neither analyte differed between groups at any stage. This adds further evidence supporting metformin as a safe alternative treatment to insulin in GDM. Further investigation is needed to evaluate whether women treated with metformin for longer periods in pregnancy require additional B12 or other supplementation.

Diet-induced paternal obesity in the absence of diabetes diminishes the reproductive health of two subsequent generations of mice

BACKGROUND

Obesity and related conditions, notably subfertility, are increasingly prevalent. Paternal influences are known to influence offspring health outcome, but the impact of paternal obesity and subfertility on the reproductive health of subsequent generations has been overlooked.

METHODS

A high-fat diet (HFD) was used to induce obesity but not diabetes in male C57Bl6 mice, which were subsequently mated to normal-weight females. First-generation offspring were raised on a control diet and their gametes were investigated for signs of subfertility. Second-generation offspring were generated from both first generation sexes and their gametes were similarly assessed.

RESULTS

We demonstrate a HFD-induced paternal initiation of subfertility in both male and female offspring of two generations of mice. Furthermore, we have shown that diminished reproductive and gamete functions are transmitted through the first generation paternal line to both sexes of the second generation and via the first generation maternal line to second-generation males. Our previous findings that founder male obesity alters the epigenome of sperm, could provide a basis for the developmental programming of subfertility in subsequent generations.

CONCLUSIONS

This is the first observation of paternal transmission of diminished reproductive health to future generations and could have significant implications for the transgenerational amplification of subfertility observed worldwide in humans.

Maternal low-dose porcine somatotropin treatment in late gestation increases progeny weight at birth and weaning in sows but not in gilts

Birth weight positively predicts postnatal growth and performance in pigs and can be increased by sustained maternal porcine ST (pST) treatment from d 25 to 100 of pregnancy (term ∼115 d). The objective of this study was to test whether a shorter period of maternal pST treatment in late pregnancy (d 75 to 100) could also increase birth and weaning weights of progeny under commercial conditions. Gilts (parity 0) and sows (parities 2 and 3) were not injected (controls) or injected daily with pST (gilts: 2.5 mg•d(-1), sows: 4.0 mg•d(-1), both ∼13 to 14 μg•kg(-1)•d(-1)) from d 75 to 100 of pregnancy. Litter size and BW were recorded at birth and weaning, and dams were followed through the subsequent mating and pregnancy. Maternal pST injections from d 75 to 100 increased litter average progeny weight at birth (+96 g, P = 0.034) and weaning (+430 g, P = 0.038) in sows, but had no effect on progeny weight in gilts (each P > 0.5). Maternal pST treatment did not affect numbers of live-born piglets and increased numbers of stillborn piglets in sows only (+0.4 pigs/litter, P = 0.034). Maternal pST treatment did not affect subsequent reproduction of dams. Together with our previous data, these results suggest that sustained increases in maternal pST are required to increase fetal and postnatal growth in gilt progeny, but that increasing maternal pST in late pregnancy may only be an effective strategy to increase fetal and possibly postnatal growth in sow progeny.

The neglected role of insulin-like growth factors in the maternal circulation regulating fetal growth

Maternal insulin-like growth factors (IGFs) play a pivotal role in modulating fetal growth via their actions on both the mother and the placenta. Circulating IGFs influence maternal tissue growth and metabolism, thereby regulating nutrient availability for the growth of the conceptus. Maternal IGFs also regulate placental morphogenesis, substrate transport and hormone secretion, all of which influence fetal growth either via indirect effects on maternal substrate availability, or through direct effects on the placenta and its capacity to supply nutrients to the fetus. The extent to which IGFs influence the mother and/or placenta are dependent on the species and maternal factors, including age and nutrition. As altered fetal growth is associated with increased perinatal morbidity and mortality and a greater risk of developing degenerative diseases in adult life, understanding the role of maternal IGFs during pregnancy is essential in order to identify mechanisms underlying altered fetal growth and offspring programming.

Review: Placental programming of postnatal diabetes and impaired insulin action after IUGR

Being born small due to poor growth before birth increases the risk of developing metabolic disease, including type 2 diabetes, in later life. Inadequate insulin secretion and decreasing insulin sensitivity contribute to this increased diabetes risk. Impaired placental growth, development and function are major causes of impaired fetal growth and development and therefore of IUGR. Restricted placental growth (PR) and function in non-human animals induces similar changes in insulin secretion and sensitivity as in human IUGR, making these valuable tools to investigate the underlying mechanisms and to test interventions to prevent or ameliorate the risk of disease after IUGR. Epigenetic changes induced by an adverse fetal environment are strongly implicated as causes of later impaired insulin action. These have been well-characterised in the PR rat, where impaired insulin secretion is linked to epigenetic changes at the Pdx-1 promotor and reduced expression of this transcription factor. Present research is particularly focussed on developing intervention strategies to prevent or reverse epigenetic changes, and normalise gene expression and insulin action after PR, in order to translate this to treatments to improve outcomes in human IUGR.

139. PLACENTAL EXPRESSION OF microRNAs ALTERS WITH GESTATION IN THE GUINEA PIG

Functional development of the placenta ensures an adequate supply of nutrients for fetal growth throughout gestation. Placental nutrient transport capacity increases during gestation, through alterations in structure and abundance of its molecular determinants, including expression of Slc2a1 (glucose transporter type-1) and Slc38a2 (system A amino acid transporter), as well as Igf1and Igf2. Each of these genes are predicted targets of microRNAs. Non-coding RNAs can down-regulate, as well as activate translation, by interacting with complementary regions in the promoter, coding, or 3’UTR of target mRNAs.(1) MicroRNAs are present in the mammalian placenta,(2) but little is known about developmental changes in their expression and actions. We hypothesised that placental expression of microRNAs which target molecular mediators of nutrient transport changes during gestation. Expression of microRNAs in the guinea pig placenta was examined at D30 (n = 7) and D60 (n = 7) of gestation (term = D70) by Exiqon microarray. Gene expression was measured by real-time PCR. Predicted gene targets were identified using miRecords and networks and pathways by Ingenuity Pathway Analysis. Placental expression of 119 microRNAs was upregulated (P < 0.05), and that of 40 was down-regulated (P < 0.05), at late compared to early gestation. Of the 20 most abundant differentially up- or down-regulated microRNAs, 11 are predicted to target members of solute carrier families. This includes has-miR-26a (↑2X), which is predicted to target Slc38a2 mRNA and expression of has-miR-26a and Slc38a2 was positively correlated (P < 0.02). Alternate predicted targets of has-miR-26a include networks involving amino acid metabolism, molecular transport and small molecular biochemistry. These findings support the hypotheses that gestational changes in microRNA expression act to regulate functional development of the placenta, including expression of genes that mediate nutrient transport. (1) Breving K, Esquela-Kerscher A. Int J Biochem Cell Biol 2009.(2) Barad O, et al. Genome Res 2004 14: 2486–2494.

316. MATERNAL DIETARY ARGININE SUPPLEMENTATION DURING LATE GESTATION IMPROVES REPRODUCTIVE EFFICIENCY IN PIGS

Arginine (a non-essential amino acid) and its conversion to nitric oxide (NO) can promote formation of new blood vessels and cause vasodilation. This may reduce resistance and increase blood flow to the uterus and placenta, and the delivery of nutrients for fetal growth and survival. In pregnant rats, dietary arginine deficiency causes IUGR and increases fetal death and perinatal mortality, whereas dietary arginine supplementation reverses this. Human IUGR is associated with impaired NO synthesis, and eNOS activity in umbilical vein endothelial cells, but maternal arginine supplements have produced inconclusive results. We hypothesised that maternal arginine supplementation (MAS) in the pig (a species with naturally occurring IUGR), during late gestation, when placental angiogenesis and vascularity increase, would increase birth and placental weights. Large White (LW) and Landrace (LR) gilts (n = 285) and sows (n = 326), were fed either a control or arginine supplemented (+25 g/d arginine, Nutreco Progenos premix) diet (2.5 kg/d) in late gestation (d75-term at ~114 days). Number born, born alive, still born and mummified, birth weight and d10 weight of progeny were measured. Data were analysed using Univariate ANOVA. MAS in late gestation in gilts and sows reduced the number of still born (Con: 1.17 ± 0.13 piglets/litter; Arg: 0.84 ± 0.09 piglets/litter; P = 0.046). In LW gilts, MAS increased birth weight (Con: 1.21 ± 0.05kg; Arg: 1.34 ± 0.05kg; P < 0.05), and litter birth weight (Con: 13.38 ± 0.72 kg; Arg: 15.27 ± 0.73 kg; P < 0.05). MAS also increased birth weight in LW (Con: 1.17 ± 0.06 kg; Arg: 1.30 ± 0.06 kg; P < 0.05) and LR (Con: 1.47 ± 0.05 kg; Arg: 1.60 ± 0.05 kg; P < 0.05) sows, and reduced still borns in LW sows (Con: 1.12 ± 0.14 piglets/litter; Arg: 0.77 ± 0.09 piglets/litter; P < 0.05). MAS in late gestation improves pregnancy outcomes in terms of piglet survival and birth weight, in LW and LR gilts and sows. MAS during critical periods of placental development may enhance placental-fetal blood flow and nutrient transfer, thereby improving fetal growth and survival.

103. THE EFFECT OF PATERNAL OBESITY IN MICE ON REPRODUCTIVE AND METABOLIC FITNESS OF F1 MALE OFFSPRING

We know relatively little of the consequences of male obesity for reproductive success compared to female obesity. Conflicting evidence exists in both humans and rodents regarding whether paternal obesity alters sperm motility and concentration. However, we have described impaired embryo and fetal development, and implantation, in rodents as a consequence of paternal obesity. This study investigated whether founder male obesity influenced the reproductive and metabolic fitness of males of the subsequent F1 generation. C57BL/6 founder male mice were fed a standard chow (CD) or a high-fat diet (HF) for 8wks. This increases adiposity in the absence of changes in fasting glucose levels. Males were mated to female C57BL/6 mice, and subsequent m ale F1 offspring from HF (HF-F1) or CD (CD-F1) founders were weighed weekly and maintained on standard chow. At 8 weeks and 14 weeks glucose tolerance tests were performed and following euthanasia, tissues and sperm collected. Sperm reactive oxygen species (ROS) and DNA damage levels were determined, and various organs weighed. HF-F1 male pups were significantly heavier relative to CD-F1 males (P < 0.05) although adult bodyweight did not differ significantly. Despite this, liver, pancreas, testes and epididymis weight was significantly elevated for HF-F1 males at 17wks of age (P < 0.05). At both 8wks and 14wks of age HF-F1 males were hypoglycaemic and had impaired glucose metabolism. Sperm analysis of HF-F1 males indicated a significant increase in ROS levels (P < 0.05), DNA damage (P < 0.05) and a decrease in fertilization rates in vitro (P < 0.05). This data indicates significant physiological changes and perturbed sperm parameters in F1 males as a consequence of founder male obesity. It supports further interrogation of male and female F1 offspring, and warrants examination of potential effects for a subsequent F2 population.

Maternal responses to daily maternal porcine somatotropin injections during early-mid pregnancy or early-late pregnancy in sows and gilts

Piglet neonatal survival and postnatal growth and efficiency are positively related to birth weight. In gilts, daily maternal porcine ST (pST) injections from d 25 to 100 (term approximately 115 d), but not d 25 to 50, of pregnancy increase progeny birth weight. Daily maternal pST injections from d 25 to 50 increase fetal weight at d 50 in gilts and sows. We therefore hypothesized that daily pST injections from d 25 to 100, but not d 25 to 50, of pregnancy would increase birth weight similarly in both parities. Landrace x Large White gilts and sows were uninjected (controls) or were injected daily with pST (gilts: 2.5 mg/d; sows: 4.0 mg/d, each approximately 15 microg of pST/kg per day) from d 25 to 50 or 100 of pregnancy. Litter size and BW were recorded at birth, midlactation, and weaning. Dams were followed through the subsequent mating and pregnancy. Maternal pST injections from d 25 to 100, but not d 25 to 50, increased mean piglet birth weight by 11.6% in sows (P <or= 0.001) and by 5.6% in gilts (P = 0.008). Both pST treatments decreased litter size by approximately 0.6 live-born piglets (each P <or= 0.025). In sows, maternal pST treatment from d 25 to 100 increased culls at weaning (P = 0.037). In remated dams, prior treatments did not affect (P > 0.1) the weaning-remating interval, conception rate, or subsequent litter size. Greater pST-induced birth weight increases in sows than in gilts may mean that underlying metabolic or placental mechanisms for pST action are constrained by maternal competition for nutrients in rapidly growing gilts.

163. MATERNAL FOLIC ACID SUPPLEMENTATION INDUCED ALTERATIONS IN METABOLIC HEALTH OF PROGENY: ROLE OF microRNA REGULATORY NETWORKS

Background: Nutrition in early life can influence metabolic functionality in later life, in part via heritable epigenetic changes, which modify gene expression without altering DNA sequence. Folate supplies methyl groups for the methylation of DNA and histones, both major epigenetic marks that change dynamically in utero. We have recently shown that maternal folic acid supplementation (MFAS) in the pregnant rat increases insulin sensitivity in adult male progeny, while decreasing that of females. The molecular basis of this is unknown but microRNAs may play a role. MicroRNAs are epigenetically regulated non-coding RNAs that downregulate post-transcriptional expression of their targets. MFAS may modulate epigenetics and expression of microRNAs and their targets in adult progeny to alter insulin sensitivity. Aims/Hypotheses: The effect of MFAS before and throughout pregnancy on microRNA expression in liver and skeletal muscle of adult progeny was determined. Methods: Female Wistar rats were fed Control (n=11) or Folic Acid Supplemented (n=9) diets containing either 2 or 6 mg folic acid/kg respectively, from two weeks before mating and throughout pregnancy. One male and female progeny per litter were sacrificed on postnatal day 90 and microRNA expression was determined by Exiqon microRNA microarray v.8.1. Results: MFAS altered hepatic microRNA expression in adult male progeny, but did not alter that in females. Sixteen hepatic microRNAs were differentially expressed, with five predicted in silico (rno-miR: 23a, 23b, 212, 298 and 325-5p) to target several key insulin signalling molecules (p85α, p110β, Akt2, and Prkcz). miR-122a, which promotes cholesterol and lipid synthesis in vivo, was also downregulated. MFAS did not alter microRNA expression in skeletal muscle of adult male or female progeny. Conclusions: MFAS alters hepatic microRNA expression in adult male progeny. Changes in their expression together with their targets in insulin signalling pathway may initiate increased insulin sensitivity in adult male progeny.

159. MATERNAL NUTRITION AND GESTATIONAL AGE AFFECT PLACENTAL microRNA EXPRESSION IN THE GUINEA PIG

Maternal undernutrition restricts placental growth and nutrient supply to the fetus, but induces compensatory alterations in structure and function of the placenta. Maternal undernutrition in guinea pigs also restricts placental growth and alters structure, and changes expression of Igf1, Igf2, Slc2a1, Slc38a2 mRNA in mid and late gestation, consistent with nutritionally induced changes in nutrient transport across the placenta. MicroRNAs are non-coding RNAs that regulate expression of target genes by translational inhibition and mRNA degradation and are present in the mammalian placenta. Effects of maternal undernutrition on their expression are unknown. We hypothesised that altered expression of key functional genes in the placenta in maternal undernutrition are in part due to altered expression of regulatory microRNAs. The effect of maternal food restriction on the expression of microRNAs in the guinea pig placenta was examined at D30 and D60 of gestation (term = D70). Guinea pigs were fed either ad libitum (AL) or restricted (R). MicroRNA expression was determined by Exiqon microarray v.8.1. In AL placentas, 119 microRNAs were upregulated (p<0.05), whilst 40 were down-regulated (p<0.05) at late compared to early gestation. In R placentas, 163 microRNAs were upregulated (p<0.05), whilst 123 were down-regulated (p<0.05) at late compared to early gestation. Of the 20 most abundant up-regulated microRNAs miR-Plus (ID 17871) and hsa-miR-411 were altered only in AL and hsa-miR-376a and -376b were altered only in R placenta. Of the 20 most abundant down-regulated microRNAs, 13 were altered only in AL and 14 only in R placentas. Placental expression of microRNAs changed with gestation, and maternal undernutrition modified this pattern and altered expression of many additional microRNAs in the guinea pig placenta. This suggests that miRNAs and factors that influence their expression may play a role in the structural and/or functional development of the placenta and hence fetal growth.

160. THE POTENTIAL ROLE OF microRNAs IN THE DEVELOPMENT OF THE HUMAN PLACENTA IN EARLY PREGNANCY

Placental functional development is characterised by dynamic and co-ordinated changes in expression of genes that drive invasion, differentiation and growth. These changes may arise in part from altered expression of microRNAs (miRNAs) via their regulatory networks. MiRNAs are short, single-stranded, non-coding RNAs involved in the post-transcriptional repression of gene expression. MiRNAs bind to complementary sites in the 3'UTR of target mRNAs to repress or silence translation. MiRNAs have been detected in the mammalian placenta, but their patterns of expression throughout pregnancy have not been systematically characterized. Using microarrays, miRNA gene expression was compared at two stages (6–8 weeks, 10–12 weeks) in early gestation, in chorionic villi of human placentas (term ~40 weeks). Putative and validated targets of differentially expressed miRNAs were extracted from freely accessible databases, miRBase [1], PicTar [2], TargetScan [3] and miRecords [4]. 15 miRNAs were differentially expressed between these gestational ages (p<0.05). 11 of these miRNAs were upregulated in 10–12 week villi and 4 were downregulated. Many of the differentially expressed miRNAs are members of the same polycistronic clusters, suggesting that these miRNAs may be co-expressed. Shared targets of differentially expressed miRNAs from the same clusters were assessed using Ingenuity Pathways Analysis, to search for significantly represented molecular networks. All downregulated miRNAs at 10–12 weeks shared 35 putative targets and fell into 1 of 2 clusters, on chromosome 13 or X. Previously validated targets include PTEN [5], Notch1 [6], VEGFA [7], CDKN2A [8] and DHFR [9] . Six of the upregulated miRNAs at 10–12 weeks are members of 3 clusters on chromosome 19, 9 and X. Networks targeted by these cluster members include PTEN, HIF1α and IL-12 signalling. Together all of these processes are active and important in early placentation and their predicted targeting by differentially expressed miRNAs is consistent with an important role in placental development.

162. THE EFFECT OF MATERNAL FOLIC ACID SUPPLEMENTATION THROUGHOUT PREGNANCY ON NEURODEVELOPMENT, MOTOR FUNCTION AND BEHAVIOUR OF PROGENY IN THE RAT

Background: Maternal folic acid supplementation (mFAS) during early pregnancy is recommended to reduce the incidence of neural tube defects and has recently been associated with improved neurodevelopment in children. However, the effect on neurodevelopment of mFAS from before conception and throughout pregnancy is unknown. We examined the effect of mFAS throughout the gestational period on postnatal growth, neurodevelopment and early adult motor function and behaviour in rat offspring. Methods: Female Wistar Rats were fed either a control (folic acid 2mg/kg, n=6) or moderate mFAS diet (folic acid 6mg/kg, n=6) from two weeks before mating with Lewis males, until birth of progeny. Male and female progeny (Control=36, mFAS=36) were weighed on postnatal day (PD) 3, 7, 14, 21, 40 and 90, and underwent various tests between PD4 and 14: righting reflex, palm-grasp reflex, negative geotaxis, forelimb hanging, ascent test and eye opening. Locomotor/ exploratory behaviour, motor coordination and anxiety were assessed using an open field test (PD52), rotarod (PD55) and elevated plus maze (PD58) (Control=24, mFAS=24). Results: mFAS did not alter maternal weight gain, litter-size at birth or progeny growth between PD3-90. mFAS tended to increase righting reflex time (p=0.057) and impair ascent ability (p=0.085). Negative geotaxis time was reduced at PD7 but not later (Diet x Age p=0.051). mFAS increased the proportion of progeny with eyes open at PD14 (p=0.008) and tended to increase forelimb hanging time(p=0.097). mFAS did not alter motor learning/function (rotarod), but increased ambulatory and exploratory behaviour (open field test; p=0.027). Conclusions: mFAS delays some early aspects of neurodevelopment including neonatal postural reflex maturation and proprioceptive/vestibular function, but accelerates others such as eye opening. However, the open field test indicated that mFAS improved the offspring's locomotion and exploratory behaviours in adulthood. Further studies will differentiate the neurodevelopmental effects of mFAS around conception from gestation-long mFAS.

Intrafetal insulin-like growth factor-I infusion stimulates adrenal growth but not steroidogenesis in the sheep fetus during late gestation

We investigated the effects of an intrafetal infusion of IGF-I on adrenal growth and expression of the adrenal steroidogenic and catecholamine-synthetic enzyme mRNAs in the sheep fetus during late gestation. Fetal sheep were infused for 10 d with either IGF-I (26 microg/kg.h; n = 14) or saline (n = 10) between 120 and 130 d gestation, and adrenal glands were collected for morphological analysis and determination of the mRNA expression of steroidogenic and catecholamine-synthetic enzymes. Fetal body weight was not altered by IGF-I infusion; however, adrenal weight was significantly increased by 145% after IGF-I infusion. The density of cell nuclei within the fetal adrenal cortex (the zona glomerulosa and zona fasciculata), and within the adrenaline synthesizing zone of the adrenal medulla, was significantly less in the IGF-I-infused fetuses compared with the saline-infused group. Thus, based on cell-density measurements, there was a significant increase in cell size in the zona glomerulosa and zona fasciculata of the adrenal cortex and in the adrenaline-synthesizing zone of the adrenal medulla. There was no effect of IGF-I infusion on the adrenal mRNA expression of the steroidogenic or catecholamine-synthetic enzymes or on fetal plasma cortisol concentrations. In summary, infusion of IGF-I in late gestation resulted in a marked hypertrophy of the steroidogenic and adrenaline-containing cells of the fetal adrenal in the absence of changes in the mRNA levels of adrenal steroidogenic or catecholamine-synthetic enzymes or in fetal plasma cortisol concentrations. Thus, IGF-I infusion results in a dissociation of adrenal growth and function during late gestation.

Maternal exposure to dexamethasone or cortisol in early pregnancy differentially alters insulin secretion and glucose homeostasis in adult male sheep offspring

An adverse intrauterine environment increases the risk of developing various adult-onset diseases, whose nature varies with the timing of exposure. Maternal undernutrition in humans can increase adiposity, and the risk of coronary heart disease and impaired glucose tolerance in adult life, which may be partly mediated by maternal or fetal endocrine stress responses. In sheep, dexamethasone in early pregnancy impairs cardiovascular function, but not glucose homeostasis in adult female offspring. However, male offspring are often more susceptible to early life "programming". Pregnant sheep were infused intravenously with saline (0.19 ml/h), dexamethasone (0.48 mg/h), or cortisol (5 mg/h), for 2 days from 26 to 28 days of gestation. In male offspring, size at birth and postnatal growth were measured, and glucose tolerance [intravenous glucose tolerance test (IVGTT)], insulin secretion, and insulin sensitivity of glucose, alpha-amino nitrogen, and free fatty acid metabolism were assessed at 4 yr of age. We show that cortisol, but not dexamethasone, treatment of mothers causes fasting hyperglycemia in adult male offspring. Maternal cortisol induced a second-phase hyperinsulinemia during IVGTT, whereas maternal dexamethasone induced a first-phase hyperinsulinemia. Dexamethasone improved glucose tolerance, while cortisol had no impact, and neither affected insulin sensitivity. This suggests that maternal glucocorticoid exposure in early pregnancy alters glucose homeostasis and induces hyperinsulinemia in adult male offspring, but in a glucocorticoid-specific manner. These consequences of glucocorticoid exposure in early pregnancy may lead to pancreatic exhaustion and diabetes longer term and are consistent with stress during early pregnancy contributing to such outcomes in humans.

Sex-specific effects of placental restriction on components of the metabolic syndrome in young adult sheep

Prenatal and early postnatal life experiences, reflected by size at birth and postnatal catch-up growth, contribute to the risk of developing the metabolic syndrome in adulthood, but their relative importance is unclear. Therefore, we determined the effects of restricted placental and fetal growth on components of the metabolic syndrome in young adult sheep and the relationships of the latter to size at birth and early postnatal growth. Fasting plasma metabolites, glucose tolerance (by intravenous glucose tolerance test, IVGTT), insulin secretion and sensitivity, and resting blood pressure were measured in 22 control and 20 placentally restricted (PR) 1-yr-old sheep. In male sheep, PR increased the initial rise in glucose during an IVGTT and reduced diastolic blood pressure, and small size at birth independently predicted reduced adult size, glucose tolerance, and fasting plasma insulin and insulin disposition of glucose metabolism but increased insulin disposition of circulating FFAs. Also in males, high fractional growth rates in early postnatal life independently predicted impaired early glucose clearance during an IVGTT. In female animals, PR increased insulin sensitivity of glucose metabolism and reduced fasting plasma FFAs, and thinness at birth predicted increased adult size, fasting blood glucose, and pulse pressure. In conclusion, PR and small size at birth are associated with more components of the metabolic syndrome in adult male than in adult female sheep, with few independent effects of early postnatal growth. These sex differences in the onset and extent of adverse metabolic consequences after prenatal restraint in the sheep are consistent with observations in humans.

Late pregnancy increases hepatic expression of insulin-like growth factor-I in well nourished guinea pigs

Blood IGF-I concentrations are persistently elevated throughout pregnancy in humans and guinea pigs and may regulate substrate partitioning between mother and conceptus. In the guinea pig, liver and adipose tissue have recently been suggested to contribute to the increased levels of circulating IGF-I in mid-pregnancy, but whether this persists in late pregnancy in undernutrition is not known. Therefore the effect of pregnancy and undernutrition on circulating IGF-I and hepatic expression of IGF-I in late gestation in the guinea pig was examined. Female guinea pigs (Cavia porcellus) were fed ad libitum throughout pregnancy or 70% of ad libitum intake for 28 days prior to and throughout pregnancy (term is 69 d). Non-pregnant animals were maintained for 88 days on the same diets. Plasma IGF-I was measured by RIA after molecular sieving chromatography at low pH. Abundances of IGF-I and beta-actin mRNA in maternal liver were quantified by digoxigenin-ELISA after RT PCR. Late pregnancy increased both the concentration of IGF-I protein (p<0.001) in plasma and the relative abundance of liver IGF-I mRNA (p<0.001) in ad libitum fed, but not in feed restricted pregnant guinea pigs. The concentration of IGF-I protein in plasma correlated positively with the relative abundance of IGF-I mRNA in liver overall (p<0.002), suggesting the liver as a major source of endocrine IGF-I in late pregnant guinea pigs. This study demonstrates that hepatic expression of IGF-I remains elevated during late pregnancy in the well fed guinea pig, which is in contrast to that observed in other non-human species.

Myogenesis in sheep is altered by maternal feed intake during the peri-conception period

The effect of varying short-term maternal feed intake during the peri-conception period on the development of ovine fetal muscle at mid-gestation was investigated. Superovulated donor Merino ewes (n = 24) were fed a roughage/grain pelleted diet (10.1 MJME/kg dry matter) at either 1.5x maintenance (H; high) or 0.5x maintenance (L; low) from 18 days before until 6 days after ovulation. Embryos were transferred to recipient ewes (n = 60) on day 6. Singleton fetuses were collected on day 75 of gestation and placental weights, fetal body dimensions and fetal organ and muscle weights recorded. The number, type and size of muscle fibres and the dry matter, RNA, DNA and protein content in the semitendinosus muscle were determined. Maternal feed intake did not influence body dimensions, organ development or muscle weights in the fetus. However, L feed intake decreased total muscle fibre number in the fetus by approximately 20% (P = 0.06) compared to H feed intake. This resulted from a reduced secondary to primary fibre ratio (P < 0.05) and indicated that secondary fibre formation occurred at a reduced rate in L fetuses. In addition, protein:DNA ratio tended to be lower in muscles of L fetuses (P < 0.1). It is concluded that restricting feed intake over the peri-conception period reduces or delays myogenesis in fetal sheep. The potential mechanisms by which nutritional availability during this period may influence subsequent myogenic development are discussed.

Postnatal ontogeny of glucose homeostasis and insulin action in sheep

Glucose tolerance declines with maturation and aging in several species, but the time of onset and extent of changes in insulin sensitivity and insulin secretion and their contribution to changes in glucose tolerance are unclear. We therefore determined the effect of maturation on glucose tolerance, insulin secretion, and insulin sensitivity in a longitudinal study of male and female sheep from preweaning to adulthood, and whether these measures were related across age. Glucose tolerance was assessed by intravenous glucose tolerance test (IVGTT, 0.25 g glucose/kg), insulin secretion as the integrated insulin concentration during IVGTT, and insulin sensitivity by hyperinsulinemic-euglycemic clamp (2 mU insulin.kg(-1).min(-1)). Glucose tolerance, relative insulin secretion, and insulin sensitivity each decreased with age (P < 0.001). The disposition index, the product of insulin sensitivity, and various measures of insulin secretion during fasting or IVGTT also decreased with age (P < 0.001). Glucose tolerance in young adult sheep was independently predicted by insulin sensitivity (P = 0.012) and by insulin secretion relative to integrated glucose during IVGTT (P = 0.005). Relative insulin secretion before weaning was correlated positively with that in the adult (P = 0.023), whereas glucose tolerance, insulin sensitivity, and disposition indexes in the adult did not correlate with those at earlier ages. We conclude that glucose tolerance declines between the first month of life and early adulthood in the sheep, reflecting decreasing insulin sensitivity and absence of compensatory insulin secretion. Nevertheless, the capacity for insulin secretion in the adult reflects that early in life, suggesting that it is determined genetically or by persistent influences of the perinatal environment.

285.Increased perinatal mortality following restriction of placental and fetal growth

Intrauterine growth restriction and subsequent low birth weight in humans are associated with increased perinatal mortality and morbidity. Impaired placental function is a major cause of IUGR in humans, but its impact on perinatal survival has not been clearly defined. We have therefore investigated the effect of restriction of placental and fetal growth on perinatal survival and behaviour in the neonatal lamb. Placental growth was surgically restricted (PR) by removal of the majority of endometrial implantation sites prior to pregnancy, leaving either 6 to 7 (moderate PR) or 3 to 4 (severe PR) visible caruncles in each uterine horn, and ewes were mated following at least 10 weeks recovery. Perinatal outcomes (stillbirths and neonatal death before 3 days of age) were recorded in a cohort of 48 control (30 singleton, 18 twin) and 28 moderate PR (14 singleton, 14 twin), and 21 severe PR (11 singleton, 10 twin) lambs, and effects of PR or twinning were evaluated by Chi-square analysis. Rates of stillbirth (P = 0.006) and total perinatal deaths (P < 0.001) were higher in severe PR pregnancies than in control or moderate PR lambs, overall (see Table in PDF file). Similarly, severe PR increased stillbirths and perinatal deaths in twins alone (P = 0.003 and P = 0.015 respectively), but the effects of PR were not significant in singletons (P = 0.10, P = 0.26 respectively). Twinning increased stillbirths and perinatal deaths overall (P = 0.002, P = 0.001) and in control lambs alone (P = 0.038, P = 0.017). Restricted fetal growth due to twinning or severe surgical restriction of placental growth thus decreases perinatal survival, due to increased stillbirths. We will further investigate the characteristics of neonatal morbidity following PR by recording neonatal behaviour, including time taken to stand and suckle, in a subsequent cohort of control and PR lambs.

273.Insulin-like growth factor treatment of pregnant guinea pigs during early pregnancy promotes fetal growth

Insulin-like growth factor (IGF)-II is an important regulator of growth in many tissues and is abundantly expressed in the placenta during pregnancy. Gene ablation studies performed in mice have shown that IGF-II deficiency results in both impaired fetal and placental growth, whereas deficiency in IGF-I reduces fetal growth only. Conversely, maternal IGF supplementation in early pregnancy in the guinea pig increases placental and fetal size by mid pregnancy. This study aimed to determine whether these anabolic effects persist into late pregnancy after cessation of treatment. On Day 20 of pregnancy, mothers were anaesthetised and a mini osmotic pump was implanted subcutaneously, to deliver 1mg/kg/day IGF-I (n = 7), IGF-II (n = 9) or vehicle (n = 7) for 17 days. Guinea pigs were killed on Day 62 of pregnancy (term ~67 days). Fetal and placental weights, and maternal and fetal body composition, were measured. Total litter size was unaffected by IGF treatment; however, IGF-II increased the number of viable fetuses by 26% (P = 0.01). After adjusting for the number of viable pups per litter, maternal IGF treatment increased fetal growth by increasing abdominal circumference, crown-rump length and fetal weight (fetal weight: IGF-I 79+/–2.5 g; IGF-II 78+/–2.6 g; vs vehicle 68+/–2.5 g, P = 0.02). IGF treatment did not alter absolute or relative fetal organ weights. IGF-I reduced placental weight by 9% and IGF-II increased it by 9%, but not significantly. IGF-I increased the fetal weight�:�placental weight ratio (19+/–0.9 vs 15+/–0.9, respectively P = 0.043). IGF treatment did not affect maternal weight gain during pregnancy nor net carcass weight; however, IGF-I reduced maternal lung and adipose tissue weights. In conclusion, maternal IGF-II treatment during early pregnancy improved fetal growth into late gestation, possibly by modulating placental efficiency. As poor placental development is implicated in fetal growth restriction, increasing maternal IGF abundance in early to mid pregnancy may be a potential therapeutic approach to placental insufficiency.

Whey proteins protect more than red meat against azoxymethane induced ACF in Wistar rats

Protein type and density have been shown to influence colon cancer risk using a carcinogen-induced rat model. It is suggested that red meat may promote colon cancer risk more than whey proteins. The aim of this study was to evaluate the influence of red meat, whey protein and their density in the diet on the number of aberrant crypt foci (ACF), preneoplastic markers in Wistar rats. The sources of protein, red meat as barbecued kangaroo muscle meat, and whey protein concentrate were fed to rats to provide 8, 16 and 32% protein by weight in a modified AIN-93 diet with low fiber, low calcium and high polyunsaturated fat. Adult Wistar rats (13 weeks of age) were fed these diets for 4 weeks and then two s.c. injections of azoxymethane, 15 mg/kg BW, were administered 1 week apart. Diets were fed for a further 8 weeks, rats were then killed, their colons fixed in formalin saline and stained with methylene blue to quantify ACF number. Fecal samples were collected and the fecal water was isolated for quantification of heme and thiobarbituric acid reactive substances. Increasing red meat density correlated positively, while increasing dairy protein density correlated negatively with rate of weight gain (p<0.05). Dietary intake was not significantly affected by protein type or density. The 32% whey protein group had significantly less ACF in the proximal colon in comparison to the 16 and 32% red meat groups (p<0.05). This reduction in ACF number in the whey protein group may be caused by hormones associated with the reduction in weight gain, and/or by components of whey protein concentrate such as cysteine, lactose and conjugated linoleic acid which have been shown to have anti-cancer effects. Using ACF number as an index, whey protein appeared to be more protective than red meat.

Circulating insulin-like growth factor (IGF)-I and IGF binding proteins -1 and -3 and placental development in the guinea-pig

Restricting maternal nutrition before and throughout pregnancy in the guinea-pig restricts foetal growth in part by altering placental structural determinants of substrate transfer function. The insulin-like growth factors have been implicated in mediating these changes. To assess the role of IGF-I in placental adaptation to maternal undernutrition, we examined the associations of circulating IGF-I and IGF binding proteins -1, -3 and -4 in the mother with placental structural development. In both mid- and late pregnancy, maternal food restriction reduced maternal plasma IGF-I by 56 per cent (P<0.0005) and 50 per cent (P<0.0005) respectively, and plasma IGFBP-3 by 47 per cent (P=0.03) and 55 per cent (P=0.002), respectively. Maternal plasma IGFBP-4 was reduced by 45 per cent (P=0.041) in food restricted guinea-pigs in mid-pregnancy but not late in pregnancy, while IGFBP-1 was unaltered at both stages. Late in pregnancy, food restriction reduced the ratio of maternal circulating IGF-I to IGFBP-1 by 52 per cent (P=0.011) and increased the ratio of IGF-I to IGFBP-3 in maternal plasma by 10 per cent (P=0.011). The relationships between the maternal IGF axis and structural correlates of placental function were assessed using pooled data from both ad libitum fed and food restricted animals. In mid-pregnancy, the volume density of the maternal blood space in the placental labyrinth correlated positively with both maternal plasma IGF-I and IGFBP-3, while maternal blood space volume correlated negatively with maternal plasma IGFBP-1. In late pregnancy, placental weight correlated positively with both maternal plasma IGF-I and IGFBP-4, while the surface area of syncytiotrophoblast and weight of trophoblast correlated positively, and mean syncytiotrophoblast thickness negatively, with maternal plasma IGF-I. Late in pregnancy, the volume density and weight of syncytiotrophoblast, the surface density and total surface area of trophoblast and the volume of the maternal blood space each correlated positively, and syncytiotrophoblast thickness correlated negatively with maternal plasma IGFBP-3. Concomitantly, placental weight, placental diameter, placental volume, volume density and weight of syncytiotrophoblast, weight of foetal capillaries, syncytiotrophoblast surface density and total syncytiotrophoblast surface area in the placental labyrinth, each correlated positively with the ratio of IGF-I to IGFBP-1 in maternal plasma, while syncytiotrophoblast thickness correlated negatively with this ratio. In late pregnancy therefore, increased trophoblast abundance and placental vascularity, and a reduced barrier to diffusion between maternal and foetal blood, occurs in association with increased abundance of IGF-I and its major carrier, IGFBP-3, and a reduction in that of IGFBP-1 in maternal blood in the guinea-pig. This suggests that systemic IGF-I and modulation of its bioavailability by IGFBPs -1 and -3 within the mother may influence placental growth and differentiation in an endocrine fashion, particularly when nutrition is limited.

Role of pituitary POMC-peptides and insulin-like growth factor II in the developmental biology of the adrenal gland

During fetal life, it is critical that there is coordinate regulation of the growth, zonation and differentiation of the fetal adrenal cortex to ensure that cells in key tissues and organs are exposed in a programmed temporal sequence to the actions of glucocorticoids. Glucocorticoids are essential for maturation of key target organs before birth, including the lung, brain, liver, gut, kidney and adrenal, and the prepartum increase in glucocorticoid synthesis and secretion by the fetal adrenal gland is critical for the successful transition to postnatal life. It is also evident that premature or abnormal exposure of embryonic or fetal tissues to glucocorticoids during critical windows of development can irreversibly alter the programmed development of organ systems. Premature or abnormal exposure of the fetus to excess glucocorticoids may occur either as a consequence of endogenous stimulation of the fetal hypothalamo-pituitary-adrenal axis (HPAA) or as a consequence of exposure to exogenous glucocorticoids in a therapeutic context. Administration of synthetic glucocorticoids to women at risk of preterm labour, for example, is a routine clinical practice designed to improve respiratory function and neonatal outcome. It is clearly important to understand what endogenous factors regulate the growth and functional maturation of the adrenal cortex during development and the consequent likelihood of exposure of developing tissues to excess corticosteroids. To date, investigations have centred on the role of ACTH 1-39 in the stimulation of adrenal growth and steroidogenesis in long gestation species, such as the primate and sheep, where maturation and differentiation of organ systems occurs predominantly before birth. In this review, we will focus on the evidence that in addition to ACTH 1-39, other pro-opio-melanocortin (POMC) derived peptides, which are synthesized, processed and secreted by the fetal pituitary, play a role in the coordinate regulation of the specific phases of growth and functional development of the fetal adrenal gland in vivo. We will discuss our recent findings on the direct in vivo actions of N-POMC 1-77 and separately, insulin like growth factor II (IGF-II), as adrenal growth factors. These studies provide an understanding of the separate regulatory mechanisms which control activation of adrenal growth and stimulation of adrenal steroidogenesis in the late gestation fetus.

Perinatal growth and plasma GH profiles in adolescent and adult sheep

Poor prenatal growth is associated with limited evidence of GH deficiency in adult humans, which may contribute to their increased risk of cardiovascular and metabolic disease. We therefore examined the effects of placental restriction of fetal growth (PR) on size at birth, neonatal fractional growth rate (FGR) and the circulating GH profile in adolescent and young adult sheep of both sexes. Moderate or severe PR decreased birth size and increased neonatal FGR of weight, crown-rump length and abdominal circumference. In adolescent males, mean and baseline GH concentrations correlated negatively and independently with birth weight and FGR of weight, and mean GH concentrations correlated negatively with current weight. In young adult males, mean GH concentrations correlated negatively and independently with birth shoulder height and FGR of shoulder height whilst, in young adult females, these correlations were positive. This suggests that restricted fetal growth and reduced neonatal growth rate in sheep are followed by elevated circulating GH in adolescent and adult males, but GH deficiency or increased GH clearance in adult females.

Maternal nutrition affects the ability of treatment with IGF-I and IGF-II to increase growth of the placenta and fetus, in guinea pigs

The aim of this study was to investigate how administration of IGF-I and IGF-II, during early to mid pregnancy, affects maternal growth and body composition as well as fetal and placental growth, in ad libitum fed, and in moderately, chronically food restricted guinea pigs. From day 20 of gestation, mothers (3-4 months old) were infused with IGF-I, IGF-II (565 microg/day) or vehicle for 17 days and then killed on day 40 of gestation. Maternal organ weights, fetal and placental weights were assessed. Treatment with IGFs did not alter body weight gain and had small effects on body composition in the mothers. Both IGF-I and IGF-II increased fetal and placental weights in ad libitum fed dams and IGF-I increased placental weight in food restricted dams. In conclusion, treatment with IGF-I during the first half of pregnancy stimulates placental growth in both ad libitum fed and food restricted guinea pigs without affecting maternal growth while fetal growth is stimulated by IGF treatment only in ad libitum fed animals.

Sleep loss and fatigue in medical training

The effects of sleep loss and fatigue in the context of medical training is a topic that has generated considerable interest, as well as controversy, over the past two decades. The sleep deprived state in medical trainees potentially impacts on a variety of domains relevant to medical care, including performance on neurobehavioral and work-related tasks, mood and affect, learning, risk for and commission of medical errors, and the health and well-being of medical students and residents. The following review provides a summary of research conducted on this topic in the past decade, including the relation of sleep loss and fatigue to medical errors and the quality of patient care. Those few studies that have analyzed the use of operational alertness management strategies, countermeasures, and educational interventions to address and mitigate the effects of sleep loss and fatigue are also reviewed. There is clearly a need for additional research to further explore the complex interaction between sleep and fatigue and medical care, and to support the development and implementation of regulatory policies based on sound science.

The practice of pediatric sleep medicine: results of a community survey

OBJECTIVE

To assess knowledge, screening, evaluation, treatment practices, and attitudes regarding sleep disorders in children and adolescents in a large sample of community-based and academic pediatricians.

DESIGN

Cross-sectional survey.

PARTICIPANTS

Six hundred twenty-six pediatricians in Rhode Island, Massachusetts, and Connecticut. INTRUMENT: The Pediatric Sleep Survey, a 42-item questionnaire assessing general and specific sleep knowledge categories; clinical screening, diagnostic, and treatment practices for common pediatric sleep disorders; and practitioner attitudes regarding the impact of sleep disorders in the clinical setting and as a public health issue.

RESULTS

On the knowledge section, the mean Total Knowledge score for the respondents was 18.1 +/- 3.5 out of 30 items, with 23.5% of the sample responding correctly on half or less of the items. Pediatricians scored highest on items relating to developmental and behavioral aspects of sleep and parasomnias, whereas the mean percentage of correct responses was <50% for items relating to sleep disordered breathing, excessive daytime sleepiness, and sleep movement disorders. Although only 16.5% and 18.2% of the sample reported not screening routinely for sleep disorders in infants and toddlers, this percentage rose to 43.9% in adolescents. Furthermore, only 38.3% regularly question the adolescents themselves about their sleep. Only about one quarter of the respondents screen toddlers and school-aged children for snoring. In evaluating and treating pediatric sleep problems, 53.2% of the sample never or rarely order overnight sleep studies to assess for obstructive sleep apnea and few use alternative treatment strategies, such as continuous positive airway pressure. A quarter of the sample at least occasionally recommends diphenhydramine and almost half suggests a psychological evaluation for children with night terrors. Finally, the percent of pediatricians rating the impact on children of sleep problems in a variety of domains as important or very important ranged from 49.7% (nonintentional injuries) to 92.6% (academic performance). However, only 46% of the sample felt confident or very confident about their own ability to screen for sleep problems, whereas 34.2% and 25.3% similarly rated their ability to evaluate and treat sleep problems in children.

CONCLUSIONS

The results of this survey suggest that there are still significant gaps among practicing pediatricians both in basic knowledge about pediatric sleep disorders, and in the translation of that knowledge into clinical practice. Despite their acknowledgment of the importance of sleep problems, many pediatricians fail to screen adequately for them, especially in older children and adolescents. Additional educational efforts regarding pediatric sleep issues are warranted, and should be targeted at the medical school, postgraduate training, and continuing medical education levels.

Fetal growth restriction: adaptations and consequences

A range of pathophysiological factors can result in a perturbation or restriction of fetal growth, and the cardiovascular, neuroendocrine and metabolic adaptations of the fetus to these stimuli will depend on their nature, timing and intensity. The critical importance of these physiological adaptations for both immediate survival and long-term health outcomes has provided an impetus for experimental studies of the nature and consequences of specific fetal adaptations to a poor intrauterine environment. This review summarizes data from recent studies that have focused on the responses of the fetal cardiovascular, sympathoadrenal, hypothalamo-pituitary-adrenal and renin-angiotensin systems to experimental restriction of placental function in the sheep and discusses the consequences of these adaptations for fetal, neonatal and adult health.

Chronic effect of insulin-like growth factor I on renin synthesis, secretion, and renal function in fetal sheep

In the adult, insulin-like growth factor I (IGF-I) increases glomerular filtration rate (GFR) and renal blood flow (RBF) during both acute and chronic treatment. To study its effects on the developing kidney, chronically catheterized fetal sheep (120 +/- 1 days gestation) were infused intravenously for up to 10 days with 80 microgram/h IGF-I (n = 5) or vehicle (0.1% BSA in saline, n = 6). In contrast to previous acute studies in adult rats and humans, after 4 h of IGF-I fetal GFR and RBF were unchanged. Fractional sodium reabsorption increased (P < 0.05). However, by 4 days, GFR per kilogram had risen by 35 +/- 13% (P < 0.05), whereas RBF remained unchanged. Tubular growth and maturation may have occurred, as proximal tubular sodium reabsorption increased by ~35% (P < 0.005). Therefore, despite a marked increase in filtered sodium (~30%, P < 0.05), fractional sodium reabsorption did not change. Although the effects of IGF-I on renal function were delayed, plasma renin activity and concentration were both elevated after 4 h and remained high at 4 days (P < 0.05). Despite this, arterial pressure and heart rate did not change. Kidneys of IGF-I-infused fetuses weighed ~30% more (P = 0.05) and contained ~75% more renin than control fetuses (P < 0.005). Thus, in the fetus, the renal effects of long-term IGF-I infusion are very different from the adult, possibly because IGF-I stimulated kidney growth.

Responses of the fetal pituitary-adrenal axis to acute and chronic hypoglycemia during late gestation in the sheep

We investigated the response of the fetal pituitary-adrenal axis to acute and chronic hypoglycemia before and after the normal prepartum activation of this axis at around 135 days gestation (term = 147 +/- 3 days). Pregnant ewes were either well nourished (control group; n = 22) or undernourished (UN; 50% reduction in maternal nutrient intake; n = 23) during the last 30 days of pregnancy. Acute hypoglycemia was induced by intrafetal administration of insulin between 125 and 130 days gestation (control, n = 7; UN, n = 12) and between 138 and 141 days gestation (control, n = 6; UN = 9). Fetal plasma glucose concentrations were significantly lower (P < 0.005) in the UN compared with the control group throughout the insulin infusion period at both gestational age ranges. In the control group, there was no fetal ACTH response to insulin infusion before 135 days gestation, but there was a significant (P < 0.001) response after 136 days gestation. In the UN group, there was a significant ACTH response to insulin infusion both before and after 135 days gestation, and there was no difference in the fetal ACTH response between the two gestational age ranges. The plasma cortisol responses to insulin were greater (P < 0.001) after 136 days compared with before 135 days gestation in both the UN and control groups. In the control group there was no significant relationship between basal fetal plasma ACTH and glucose concentrations between 115-135 days gestation or between 136-145 days gestation. In the UN group, fetal glucose ranged from 0.5-2.0 mM, and plasma ACTH and glucose concentrations were inversely related at 115-135 days gestation [log ACTH = -0.31 (glucose) + 2.21; r = -0.37; P < 0.001] and at 136-145 days gestation [log ACTH = -0.40 (glucose) + 2.50; r = -0.54; P < 0.001]. When the UN and control groups were combined, fetal plasma ACTH concentrations were significantly greater (F = 13.5; P < 0.05) when plasma glucose concentrations were less than 1.0 mM at either 115-135 days or 136-147 days gestation. Similarly, fetal plasma cortisol concentrations were also significantly greater (F = 18.7; P < 0.05) when plasma glucose concentrations were less than 1.0 mM at each gestational age range. Therefore, there is an increased sensitivity of the fetal hypothalamo-pituitary axis to acute falls in glucose concentrations below 1.2 mM after 135 days compared with earlier in gestation. The fetal hypothalamo-pituitary axis can respond, however, when plasma glucose concentrations fall below 1.0 mM, before and after 135 days gestation, independently of whether the low glucose concentrations are a consequence of insulin-induced hypoglycemia or maternal nutrient restriction.

Altered placental structure induced by maternal food restriction in guinea pigs: a role for circulating IGF-II and IGFBP-2 in the mother?

Maternal feed restriction may restrict fetal growth in part indirectly by impairing placental functional development. Such actions could be mediated by the insulin-like growth factors (IGF), which are important modulators of placental growth and differentiation and more generally, are influenced by nutrient availability. While a role for the fetal IGF axis has been demonstrated, less is known of the influence, if any, of that in the mother. This study aimed to determine whether alterations in the maternal IGF axis and placental functional and structural development due to maternal food restriction are related. We therefore examined the associations between placental structural parameters, the ratios of maternal to fetal plasma glucose and fetal to maternal plasma urea concentration, and maternal circulating IGF-I, IGF-II and IGFBP-2 in ad libitum fed and food restricted (70-90 per cent of the ad libitum intake) pregnant guinea pigs. In mid-gestation, fetal weight (r = 0.65, P = 0.008, n = 17), volume of the maternal blood space (r = 0.58, P = 0.048, n = 17), and surface density of syncytiotrophoblast (r = 0.65, P = 0.023, n = 17), were positively correlated, and syncytiotrophoblast thickness was negatively correlated, with maternal plasma IGF-II concentration (r = -0.69, P = 0.014, n = 17). Late in gestation, fetal weight, placental weight and total exchange surface area in the placenta were each negatively correlated with maternal plasma IGFBP-2 concentration (all P < 0.01), while the arithmetic mean thickness of syncytiotrophoblast was positively correlated with maternal plasma IGFBP-2 concentration. Late in gestation, the ratio of maternal to fetal plasma glucose was positively correlated with fetal weight (r = 0.54, P = 0.038, n = 15) and the ratio of fetal to maternal plasma urea concentration was positively correlated with placental weight (r = 0.52, P=0.046, n=15). Maternal feed restriction reduced the ratio of maternal plasma IGF-II to IGFBP-2 in late gestation by 75 per cent (P = 0.001) and this ratio was positively correlated with fetal weight (r = 0.56, P = 0.01, n = 20), placental weight (r = 0.59, P = 0.006), placental diameter (r = 0.621, P = 0.003), placental volume (r = 0.57, P=0.009), weight of trophoblast (r = 0.51, P=0.037), weight of fetal capillaries (r = 0.49, P = 0.046), syncytiotrophoblast surface density (r = 0.611, P = 0.009) and negatively correlated with syncytiotrophoblast thickness (r = -0.55, P = 0.021). Our results suggest that in mid-pregnancy, maternal circulating IGF-II promotes placental structural development, while later in pregnancy, IGFBP-2 inhibits it, and their relative abundance and interaction strongly influences placental structure and function near term.

Restriction of fetal growth has a differential impact on fetal prolactin and prolactin receptor mRNA expression

Prolactin is present in the fetal circulation and prolactin receptors are expressed in a wide range of fetal tissues. The factors which regulate the synthesis and secretion of prolactin, and the expression of its receptors before birth, are poorly understood. We have investigated whether experimental restriction of placental growth in the sheep has an impact on the prolactin axis in the growth restricted fetus. The majority of uterine endometrial caruncles were removed before pregnancy in 10 ewes (placental restriction; PR group). Placental, fetal liver and kidney weights were reduced in the PR compared to the control group (n = 10). The ratio of fetal prolactin mRNA : 18S rRNA was significantly lower (P < 0.01) in the PR group (1.83 +/- 0.45, n = 6) than in the control group (4.11 +/- 0.54, n = 6). The ratio of prolactin mRNA : 18S rRNA in the fetal pituitary was positively correlated with fetal and with placental weight. Using stepwise linear regression, it was determined that the level of fetal prolactin mRNA : 18S rRNA expression was best described (as judged by the maximum adjusted R2) by prolactin mRNA: 18 S rRNA = - 3.0378 + 0.17 PO2 + 2.772 glucose (adjusted R2 = 0.765, F = 17.53, P < 0.001). Fetal plasma prolactin concentrations were significantly reduced (P < 0.05) in the PR group compared to control animals between 109 and 141 days gestation. Fetal prolactin receptor (PRLR) mRNA transcripts encoding long (PRLR1) and short forms (PRLR2) of PRLR were present in the liver and kidney of animals in the PR and control groups at 140-141 days gestation. PR did not alter the levels of PRLR1 or PRLR2 mRNA in the fetal liver or kidney. The suppression of the synthesis and secretion of prolactin in the growth restricted fetus may limit the action of prolactin on the growth and metabolism of key fetal organs during suboptimal intrauterine conditions

Maternal food restriction reduces the exchange surface area and increases the barrier thickness of the placenta in the guinea-pig

The extent to which maternal nutrition influences fetal growth through effects on placental functional development is unclear. Poor maternal nutrition is a major cause of poor fetal growth which increases neonatal morbidity and mortality, and may also increase the risk of several adult-onset diseases. We have therefore characterized the ontogeny of structural determinants of function in the placenta in guinea-pigs fed ad libitum or food restricted from before and during pregnancy. Guinea-pigs were killed at days 30 and 60 (term=67 days) of pregnancy. In ad libitum fed animals, the surface density (surface area/g placental labyrinth), which is a measure of the convolution of the exchange surface, doubled, while total surface area increased 18-fold between mid and late gestation. Concomitantly, the arithmetic mean barrier thickness to diffusion across trophoblast decreased by 68 per cent. Late in gestation, food restriction reduced the proportion of the placenta devoted to exchange (labyrinth) by 70 per cent (P< 0.04) and the weight of the placental labyrinth by 45 per cent (P=0.001). Maternal food restriction also reduced the total placental surface area for exchange by 36 per cent at day 30 (P=0.02) and 60 per cent at day 60 (P< 0.0005) of gestation, and the surface density of trophoblast by 36 per cent at day 30 (P=0.01) and 29 per cent at day 60 (P=0.005) of gestation. The arithmetic mean barrier thickness for diffusion was increased by maternal food restriction at both gestational ages (day 30, +37 per cent, P=0.008, and day 60, +40 per cent, P=0.01). These findings suggest that maternal food restriction not only reduces fetal and placental weights, but also induces structural alterations in the placenta that indicate functional impairment beyond what would be expected for the reduction in its weight.

Insulin-like growth factor I alters renal function and stimulates renin secretion in late gestation fetal sheep

While it is known that treatment with insulin-like growth factor I (IGF-I) stimulates growth of the fetal kidney, nothing is known about the short term or long term effects of IGF-I on fetal renal function. To investigate the acute effects of IGF-I on fetal renal function and on the activity of the fetal renin-angiotensin system, studies were carried out in 12 chronically catheterized fetal sheep aged 120 +/- 1 days, before and during a 4 h I.V. infusion of IGF-I at 80 ug h-1. Seven control fetuses were infused over the same period with vehicle (0.1% bovine serum albumin in 0.15 M saline). IGF-I infusion increased plasma IGF-I concentrations by about 80%. There was a small fall in arterial PO2 (P < 0.01), arterial PCO2 increased (P < 0.05), plasma lactate levels increased (P < 0.01) and arterial pH fell (P < 0.05). Fractional bicarbonate reabsorption increased and bicarbonate excretion decreased (P < 0.05). Infusions of IGF-I had no sustained effect on fetal arterial pressure. Glomerular filtration rate (GFR) did not change significantly during IGF-I infusion, but renal blood flow (RBF) fell (P < 0.05). Therefore filtration fraction relative to control values increased (P < 0.05), suggesting that efferent arteriolar vasoconstriction had occurred. IGF-I infusion led to an antidiuresis (P < 0.01), a rise in urinary osmolality (P < 0.05) and a fall in free water clearance (P < 0.01). Since fetal PO2 fell, it is probable that these effects were mediated by arginine vasopressin. The excretion rates of sodium, chloride and phosphate were all reduced by 4 h of infusion (P < 0.05), because their fractional reabsorption rates were all increased (sodium, P < 0.01; chloride, P < 0.01; and phosphate, P < 0.05). Plasma renin concentration increased by 275 +/- 52% during infusion of IGF-I (P < 0.005). Plasma renin activity also increased (P < 0.005), while circulating angiotensinogen concentrations fell (P < 0.05). In the adult, IGF-I increases both RBF and GFR, enhances tubular reabsorption and stimulates the renin-angiotensin system. In the fetus, however, it decreased RBF and had no effect on GFR, but was associated with enhanced tubular function and intense stimulation of renin secretion. Some of these effects of IGF-I on fetal renal function may be involved in maturation of the kidney in preparation for life after birth.

Fetoplacental growth in sheep administered progesterone during the first three days of pregnancy

We have previously shown that administration of progesterone during early pregnancy in sheep enhances fetal weight and crown-rump length. The present study examined the effect of this treatment on individual fetal organ weights and on placental growth and structure. Embryos that had been exposed to either a normal or a high concentration of progesterone on days 1-3 in initial recipient ewes were transferred at random to final recipient ewes that had or had not been treated with progesterone on days 1-3. Embryos in an additional group of ewes were exposed to progesterone on days 1-3 with oviducts of the ewes ligated. An increase in fetal weight was observed in the final recipient group that had been treated with progesterone (P< 0.01) but not in the initial group treated with progesterone. Fetal weight was increased (P< 0.05) in the initial recipients treated with progesterone plus ligation. Placental weight did not differ between any of the treatments in either initial or final recipients, while placental volumes of chorionic membrane and maternal crypts were increased by progesterone, with and without ligation, in initial recipients (P< 0.05). The responses of fetal weight in final recipients were associated with increases in the weight and linear dimensions of specific fetal components (e.g. brain, kidney, heart, spleen, total gut, head width, thorax circumference). Proportionate increases were observed for most parameters with the exception of brain, heart and M tibialis anterior weight; adjusted least squares means indicated disproportionate increases in these of 5 per cent, 32 per cent and 26 per cent respectively. Enhanced fetal weight in the progesterone plus ligation group was associated with increased (P< 0.05) heart weight; a disproportionate increase of 39 per cent was recorded. Increased fetal weight and fetal heart, skeletal muscle and brain weight were correlated with increased volumes and surface area of the fetal trophectoderm and maternal fetomaternal syncytium in the final recipients treated with progesterone. It is concluded that alteration of the embryo's environment during the first few days of development enhances fetal growth disproportionately, in close association with increased abundance of the exchange epithelia in the placenta.

The Children's Sleep Habits Questionnaire (CSHQ): psychometric properties of a survey instrument for school-aged children

STUDY OBJECTIVES

To present psychometric data on a comprehensive, parent-report sleep screening instrument designed for school-aged children, the Children's Sleep Habits Questionnaire (CSHQ). The CSHQ yields both a total score and eight subscale scores, reflecting key sleep domains that encompass the major medical and behavioral sleep disorders in this age group.

DESIGN

Cross-sectional survey.

SETTING

Three elementary schools in New England, a pediatric sleep disorders clinic in a children's teaching hospital.

PARTICIPANTS

Parents of 469 school-aged children, aged 4 through 10 years (community sample), and parents of 154 patients diagnosed with sleep disorders in a pediatric sleep clinic completed the CSHQ.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

The CSHQ showed adequate internal consistency for both the community sample (p=0.68) and the clinical sample (p=0.78); alpha coefficients for the various subscales of the CSHQ ranged from 0.36 (Parasomnias) to 0.70 (Bedtime Resistance) for the community sample, and from 0.56 (Parasomnias) to 0.93 (Sleep-Disordered Breathing) for the sleep clinic group. Test-retest reliability was acceptable (range 0.62 to 0.79). CSHQ individual items, as well as the subscale and total scores were able to consistently differentiate the community group from the sleep-disordered group, demonstrating validity. A cut-off total CSHQ score of 41 generated by analysis of the Receiver Operator Characteristic Curve (ROC) correctly yielded a sensitivity of 0.80 and specificity of 0.72.

CONCLUSIONS

The CSHQ appears to be a useful sleep screening instrument to identify both behaviorally based and medically-based sleep problems in school-aged children.

Origins of fetal growth restriction

Regulation of growth of the fetus and its placenta begins before pregnancy. Early in pregnancy the mother sets the rate of growth of the fetus on a trajectory, which may be modified by events later in pregnancy. Low maternal weight for height, history of previous small babies, maternal undernutrition, pregnancy disorders, e.g. pre-eclampsia, are associated with low birthweight. Maternal smoking is a major factor in developed countries; infections and undernutrition in developing countries.Recently, there has been emphasis on adverse long-term outcomes including ischaemic heart disease, hypertension and diabetes associated with poor fetal growth. Experimental studies in animals show that some of these outcomes can readily be induced by restriction of fetal growth. Progress in determining successful treatments to improve the growth of the fetus has lagged behind these epidemiological and experimental findings. However, nutrient supplements improve growth in undernourished women and smoking cessation also improves fetal size and outcome.

Development and preliminary validation of a brief broad-spectrum measure of trauma exposure: the Traumatic Life Events Questionnaire

This article describes the development and preliminary validation of a brief questionnaire that assesses exposure to a broad range of potentially traumatic events. Items were generated from multiple sources of information. Events were described in behaviorally descriptive terms, consistent with Diagnostic and Statistical Manual of Mental Disorders IV posttraumatic stress disorder stressor criterion A1. When events were endorsed, respondents were asked if they experienced intense fear, helplessness, or horror (stressor criterion A2). In separate studies with college students, Vietnam veterans, battered women, and residents of a substance abuse program, most items possessed adequate to excellent temporal stability. In a study comparing questionnaire and structured-interview inquiries of trauma history, the 2 formats yielded similar rates of disclosure. Preliminary data on positive predictive power are also presented.