Maternal and fetal determinants of adult diseases

Nutritional and non-nutritional factors associated with low birth weight in Sawula Town, Gamo Gofa Zone, Southern Ethiopia

OBJECTIVE

Birth weight is a major predictor of infant growth and survival, and is dependent on maternal health and nutrition during pregnancy. This study aimed to determine the magnitude and identify nutritional and non-nutritional factors associated with LBW among newborn in Southern Ethiopia. Institutional-based cross-sectional study was used. Systematic random sampling was employed to select the study subjects. Data were entered into Epi-info Version 3.5.3 and then exported to SPSS Version 20 for analysis. Bivariable and multivariable logistic regression were used to compare birth weight across categories of independent variables. The output of the analysis were presented using adjusted odd ratio (AOR) with the corresponding 95% confidence interval (CI).

RESULTS

A total of 358 mothers participated in the study. The mean (± standard deviation) birth weight of all term infants was 3304 (± 684) gram. The prevalence of LBW was 17.3% (95% CI 13.7-21.2%). Mothers who had MUAC less than 23 cm [AOR = 6.51 (95% CI 2.85-14.91)] and with hemoglobin < 11 mg/dl [AOR = 3.42 (95% CI 1.73-6.78)] have increased odds of delivering LBW and mothers who often take dairy products [AOR = 0.36 (95% CI 0.13-0.98)] were less likely deliver LBW babies than their counterparts.

Pretreatment Effect of Folic Acid on 13-Cis-RA-Induced Cellular Damage of Developing Midfacial Processes in Cultured Rat Embryos

OBJECTIVE

Excess treatment of 13-cis-RA (Accutane®) on pregnant women induces craniofacial malformation found in infants. However, the effect of folic acid on 13-cis-RA-induced cellular damages of developing midfacial processes is still unknown. The purpose of this study was to investigate the pretreatment effect of folic acid (FA) on 13-cis-RA-induced cellular damage in developing midfacial processes in rat embryos.

MATERIALS AND METHODS

The rat embryos at developing midfacial processes were performed by whole embryo culture in vitro, in the presence of 13-cis-RA (20 µM) with or without pre-treatment of FA (100 µM). The midfacial morphogenesis score, PCNA and TUNEL assay staining were evaluated for morphogenesis, cell proliferation and apoptosis of the midfacial processes, respectively.

RESULTS

The 13-cis-RA-treated embryos at 24h showed atrophy of midfacial processes with significantly decreased morphogenesis score and cell proliferation, and increased apoptotic cell death. In contrast, the embryos pre-treated with FA for 18h, followed by 13-cis-RA treatment for 24h (FA-RA) showed significantly greater morphogenesis score, increased cell proliferation and lower apoptotic cell death compared to those of the 13-cis-RA-treated embryos.

CONCLUSION

The results suggest that FA reduced the teratogenic effects of 13-cis-RA on midfacial process tissue. Future investigations regarding the anti-teratogenic mechanism of FA on the prevention of damages in midface processes induced by 13-cis-RA on pregnant woman are warranted.

The Nature and Nurture of Child Development

Although the reduction of child morbidity and the promotion of physical growth are important and necessary aspects of child development, these criteria by themselves do not define the adequacy of children's development. There are also behavioural-developmental criteria that emphasize the promotion of competence. the competent individual is one who can effectively adapt to and interact with his or her environment. Traits that define individual competence fall into five domains: cognitive skills, temperament/personality, motivation, self-perceptions, and interpersonal style. These domains are not completely independent, and there is at least partial overlap. the expression of individual differences in competence is partially moderated by context. Further, not all children achieve competence. Over time some children fall further and further behind their peers in their developmental course. in understanding what biological and psychosocial factors influence the development of individual differences in competence, four principles are critical.

First, most aspects of individual competence are multidetermined. This means that interventions designed to facilitate development must be multifocal in nature, integrating influences from different domains. Second, influences upon children's development tend to be specific in nature. This emphasizes the importance of targeting specific interventions to specific outcomes. Third, individual developmental influences rarely operate in isolation from each other. Developmental risk factors tend to cluster together, as do developmentally protective influences. the extent of the impact of a given developmental risk factor will depend, in part, on the degree to which this risk factor covaries with other risk factors. Fourth, developmental risk and protective factors operate across time. Early exposure to developmental risks may increase the individual's susceptibility to later risk factors (sensitizing) or may limit the degree to which the individual can profit from later exposure to protective factors such as intervention (blunting). Early exposure to developmentally protective factors may attenuate the impact of later exposure to developmental risk factors (steeling).

Principles underlying the nature and nurture of individual competence emphasize the need to use an IT-AT intervention strategy (Integrate Target Across Time). This means the need to integrate multi-domain interventions, target our intervention strategies to different contexts, risk conditions, and outcomes, and provide for recurring interventions across time to maximize the chances of long-term gains in individual competence.

Chronic disease outcomes after severe acute malnutrition in Malawian children (ChroSAM): a cohort study

BACKGROUND

Tackling severe acute malnutrition (SAM) is a global health priority. Heightened risk of non-communicable diseases (NCD) in children exposed to SAM at around 2 years of age is plausible in view of previously described consequences of other early nutritional insults. By applying developmental origins of health and disease (DOHaD) theory to this group, we aimed to explore the long-term effects of SAM.

METHODS

We followed up 352 Malawian children (median age 9·3 years) who were still alive following SAM inpatient treatment between July 12, 2006, and March 7, 2007, (median age 24 months) and compared them with 217 sibling controls and 184 age-and-sex matched community controls. Our outcomes of interest were anthropometry, body composition, lung function, physical capacity (hand grip, step test, and physical activity), and blood markers of NCD risk. For comparisons of all outcomes, we used multivariable linear regression, adjusted for age, sex, HIV status, and socioeconomic status. We also adjusted for puberty in the body composition regression model.

FINDINGS

Compared with controls, children who had survived SAM had lower height-for-age Z scores (adjusted difference vs community controls 0·4, 95% CI 0·6 to 0·2, p=0·001; adjusted difference vs sibling controls 0·2, 0·0 to 0·4, p=0·04), although they showed evidence of catch-up growth. These children also had shorter leg length (adjusted difference vs community controls 2·0 cm, 1·0 to 3·0, p<0·0001; adjusted difference vs sibling controls 1·4 cm, 0·5 to 2·3, p=0·002), smaller mid-upper arm circumference (adjusted difference vs community controls 5·6 mm, 1·9 to 9·4, p=0·001; adjusted difference vs sibling controls 5·7 mm, 2·3 to 9·1, p=0·02), calf circumference (adjusted difference vs community controls 0·49 cm, 0·1 to 0·9, p=0·01; adjusted difference vs sibling controls 0·62 cm, 0·2 to 1·0, p=0·001), and hip circumference (adjusted difference vs community controls 1·56 cm, 0·5 to 2·7, p=0·01; adjusted difference vs sibling controls 1·83 cm, 0·8 to 2·8, p<0·0001), and less lean mass (adjusted difference vs community controls -24·5, -43 to -5·5, p=0·01; adjusted difference vs sibling controls -11·5, -29 to -6, p=0·19) than did either sibling or community controls. Survivors of SAM had functional deficits consisting of weaker hand grip (adjusted difference vs community controls -1·7 kg, 95% CI -2·4 to -0·9, p<0·0001; adjusted difference vs sibling controls 1·01 kg, 0·3 to 1·7, p=0·005,)) and fewer minutes completed of an exercise test (sibling odds ratio [OR] 1·59, 95% CI 1·0 to 2·5, p=0·04; community OR 1·59, 95% CI 1·0 to 2·5, p=0·05). We did not detect significant differences between cases and controls in terms of lung function, lipid profile, glucose tolerance, glycated haemoglobin A1c, salivary cortisol, sitting height, and head circumference.

INTERPRETATION

Our results suggest that SAM has long-term adverse effects. Survivors show patterns of so-called thrifty growth, which is associated with future cardiovascular and metabolic disease. The evidence of catch-up growth and largely preserved cardiometabolic and pulmonary functions suggest the potential for near-full rehabilitation. Future follow-up should try to establish the effects of puberty and later dietary or social transitions on these parameters, as well as explore how best to optimise recovery and quality of life for survivors.

FUNDING

The Wellcome Trust.

Hypothalamic Nuclei Nitric Oxide Synthase Expression in Rats Malnourished During Early Lactation Period

In humans and other animals, it has been shown that protein malnutrition during the prenatal period leads to permanent changes, which in adulthood may cause chronic diseases. Molecules involved in the control of energy metabolism could be targets to alterations caused by nutritional status. Some hypothalamic nuclei as the paraventricular (PVN), ventro-medial and arcuate are related to energy metabolism regulation. Orexigenic and anorexigenic molecules are involved in this regulation. Some studies have showed that these nuclei present nitric oxide synthase (NOS) and that it is increased in obese rats. Recently it had been shown that rats malnourished during the lactation period presented metabolic alterations that persist in adulthood. The aim of this work was to study the expression of NOS in hypothalamic nuclei of rats submitted to malnutrition during the early lactation period. Rats from post-natal day (P10) to P90 were used. Control dams were fed with regular chow pellets and diet dams were fed with protein-free chow pellets during the first 10 days of lactation. NADPH-diaphorase or immunostaining techniques were used to access NOS expression in hypothalamic nuclei. Our results show a delay in NOS expression in the PVN and VMH of malnourished rats. It may affect the development of the hypothalamic circuitry, leading to a metabolic imprinting.

Glucocorticoid effects on the programming of AT1b angiotensin receptor gene methylation and expression in the rat

Adverse events in pregnancy may 'programme' offspring for the later development of cardiovascular disease and hypertension. Previously, using a rodent model of programmed hypertension we have demonstrated the role of the renin-angiotensin system in this process. More recently we showed that a maternal low protein diet resulted in undermethylation of the At1b angiotensin receptor promoter and the early overexpression of this gene in the adrenal of offspring. Here, we investigate the hypothesis that maternal glucocorticoid modulates this effect on fetal DNA methylation and gene expression. We investigated whether treatment of rat dams with the 11beta-hydroxylase inhibitor metyrapone, could prevent the epigenetic and gene expression changes we observed. Offspring of mothers subjected to a low protein diet in pregnancy showed reduced adrenal Agtr1b methylation and increased adrenal gene expression as we observed previously. Treatment of mothers with metyrapone for the first 14 days of pregnancy reversed these changes and prevented the appearance of hypertension in the offspring at 4 weeks of age. As a control for non-specific effects of programmed hypertension we studied offspring of mothers treated with dexamethasone from day 15 of pregnancy and showed that, whilst they had raised blood pressure, they failed to show any evidence of Agtr1b methylation or increase in gene expression. We conclude that maternal glucocorticoid in early pregnancy may induce changes in methylation and expression of the Agtr1b gene as these are clearly reversed by an 11 beta-hydroxylase inhibitor. However in later pregnancy a converse effect with dexamethasone could not be demonstrated and this may reflect either an alternative mechanism of this glucocorticoid or a stage-specific influence.

Insulin resistance markers in term, normoweight neonates. The Mérida cohort

Several endocrine regulators are implicated in the development of metabolic syndrome. The aim of our study was to assess normal ranges for glucose, growth hormone (GH), insulin-like growth factor-1 (IGF-1), cortisol, insulin and the yet-to-be-published quantitative insulin sensitivity check index (QUICKI) for newborns and a number of homeostatic model assessment (HOMA)-related equations that have been proposed as indicators of insulin sensitivity (HOMA-S) and insulin resistance (HOMA-R). The study included 115 (54 males, 61 females) singleton, normoweight, Spanish Caucasian neonates delivered without foetal distress from mothers of the Mérida (Spain) Birth Cohort who tested negative in the O'Sullivan screen. Neonatal normal values given as the mean (95% confidence interval) were: glucose, 75.3 mg/dL (68.29-82.29); cortisol, 7.4 microg/dL (6.85-7.97); GH, 16.7 ng/mL (14.87-18.60); insulin, 5.5 microUI/mL (4.12-6.88), IGF-155.2 ng/mL (50.82-59.53); QUICKI, 0.45 (0.43-0.48); HOMA-R, 1.36 (0.84-1.88); HOMA-S, 4.07 (2.66-5.49), the glucose/insulin ratio, 33.6 (24.58-42.67); the insulin/cortisol ratio, 0.8 (0.61-1.05). Hormone ranges (except for cortisol, whose values were lower) were equivalent to those of other studies. Cortisolaemia values cannot be associated with the type of delivery, as only three births (2.6%) were by caesarean section, while 20 (17.4%) were instrumental deliveries. Neonates from the lowest quartile of the insulin/cortisol ratio presented higher (p < 0.001) HOMA-S and QUICKI and lower (p < 0.01) HOMA-R values. The results of our study indicate normal ranges for insulin resistance and sensitivity at birth. The insulin/cortisol ratio at birth appears to be a good early indicator of insulin resistance.

Epidemiological and nutrition transition in developing countries: impact on human health and development

Whereas common infectious and parasitic diseases such as malaria and the HIV/AIDS pandemic remain major unresolved health problems in many developing countries, emerging non-communicable diseases relating to diet and lifestyle have been increasing over the last two decades, thus creating a double burden of disease and impacting negatively on already over-stretched health services in these countries. Prevalence rates for type 2 diabetes mellitus and CVD in sub-Saharan Africa have seen a 10-fold increase in the last 20 years. In the Arab Gulf current prevalence rates are between 25 and 35% for the adult population, whilst evidence of the metabolic syndrome is emerging in children and adolescents. The present review focuses on the concept of the epidemiological and nutritional transition. It looks at historical trends in socio-economic status and lifestyle and trends in nutrition-related non-communicable diseases over the last two decades, particularly in developing countries with rising income levels, as well as the other extreme of poverty, chronic hunger and coping strategies and metabolic adaptations in fetal life that predispose to non-communicable disease risk in later life. The role of preventable environmental risk factors for obesity and the metabolic syndrome in developing countries is emphasized and also these challenges are related to meeting the millennium development goals. The possible implications of these changing trends for human and economic development in poorly-resourced healthcare settings and the implications for nutrition training are also discussed.

The epidemiology and aetiology of Perthes' disease in Norway. A nationwide study of 425 patients

A nationwide study of Perthes' disease in Norway was undertaken over a five-year period from January 1996. There were 425 patients registered, which represents a mean annual incidence of 9.2 per 100 000 in subjects under 15 years of age, and an occurrence rate of 1:714 for the country as a whole. There were marked regional variations. The lowest incidence was found in the northern region (5.4 per 100 000 per year) and the highest in the central and western regions (10.8 and 11.3 per 100 000 per year, respectively). There was a trend towards a higher incidence in urban (9.5 per 100 000 per year) compared with rural areas (8.9 per 100 000 per year). The mean age at onset was 5.8 years (1.3 to 15.2) and the male:female ratio was 3.3:1. We compared 402 patients with a matched control group of non-affected children (n = 1 025 952) from the Norwegian Medical Birth Registry and analysed maternal data (age at delivery, parity, duration of pregnancy), birth length and weight, birth presentation, head circumference, ponderal index and the presence of congenital anomalies. Children with Perthes' disease were significantly shorter at birth and had an increased frequency of congenital anomalies. Applying Sartwell's log-normal model of incubation periods to the distribution of age at onset of Perthes' disease showed a good fit to the log-normal curve. Our findings point toward a single cause, either genetic or environmental, acting prenatally in the aetiology of Perthes' disease.

Statistical issues in life course epidemiology

There is growing recognition that the risk of many diseases in later life, such as type 2 diabetes or breast cancer, is affected by adult as well as early-life variables, including those operating prior to conception and during the prenatal period. Most of these risk factors are correlated because of common biologic and/or social pathways, while some are intrinsically ordered over time. The study of how they jointly influence later ("distal") disease outcomes is referred to as life course epidemiology. This area of research raises several issues relevant to the current debate on causal inference in epidemiology. The authors give a brief overview of the main analytical and practical problems and consider a range of modeling approaches, their differences determined by the degree with which associations present (or presumed) among the correlated explanatory variables are explicitly acknowledged. Standard multiple regression (i.e., conditional) models are compared with joint models where more than one outcome is specified. Issues arising from measurement error and missing data are addressed. Examples from two cohorts in the United Kingdom are used to illustrate alternative modeling strategies. The authors conclude that more than one analytical approach should be adopted to gain more insight into the underlying mechanisms.

Experimental Intrauterine Growth Retardation in the Rat Causes a Reduction of Pancreatic B-Cell Mass, Which Persists into Adulthood

BACKGROUND AND OBJECTIVES

The aim of this study was to investigate the possibility that intrauterine growth retardation (IUGR) causes alterations of glucose tolerance, insulin secretory response to glucose, and pancreatic B-cell growth, and if such changes may persist into adulthood.

METHODS

Pregnant rats were operated on day 16 of pregnancy ad modum Wigglesworth to induce IUGR. Operated rats gave birth to viable offspring but litter size was reduced. The mothers nursed their pups, which were subsequently weaned and reared to an age of 3 months in apparent good health.

RESULTS

At 1 day of age, IUGR pups were 10% lighter than control newborns whose mothers had been subjected to a sham operation. Pancreatic B-cell mass and insulin content were reduced by 35-40% in newborn IUGR offspring. Postnatal growth did not differ between IUGR and control animals of either sex and the difference in body weight at birth was not apparent from 1 week of age and onwards. Tests performed at 3 months of age could not demonstrate differences in glucose tolerance between IUGR and control animals. In females, but not in males, the peak insulin secretory response to glucose was lower in IUGR animals compared to controls. In the 3-month-old rats, B-cell mass was reduced by 40% in male and by 45% in female IUGR rats compared to controls, a reduction corresponding to a similar decrease in pancreatic insulin content (male reduction 48%, female reduction 45%).

CONCLUSIONS

In the rat, IUGR causes a diminution of pancreatic B-cell mass which persists into adulthood. Normal glucose tolerance could be maintained but it is conceivable that increasing demands on insulin secretion may not be met by the reduced B-cell mass and that impaired glucose tolerance and even diabetes would hence develop.

Up-regulation of phosphatidylinositol 3-kinase and glucose transporter 4 in muscle of rats subjected to maternal undernutrition

Early postnatal nutrition has been associated with the long-term effects on glucose homeostasis in adulthood. To elucidate the molecular mechanisms by which undernutrition during early life leads to changes in insulin sensitivity, we investigated the insulin signaling in skeletal muscle of rats during development. Offspring of dams fed with either protein-free or normal diets during the first 10 days of lactation were studied from lactation period until adulthood. Early maternal undernutrition impaired secretion of insulin but maintained normal blood glucose levels until adulthood. Insulin receptor (IR) activation after insulin stimulation was decreased during the period of protein restriction. In addition, glucose uptake, insulin receptor substrate 1 (IRS-1) phosphorylation and glucose transporter 4 (GLUT-4) translocation in muscle were reduced in response to insulin during suckling. In contrast, non- or insulin-stimulated glucose uptake and GLUT-4 translocation were found significantly increased in muscle of adult offspring. Finally, basal association of phosphatidylinositol 3-kinase (PI3-kinase) with IRS-1 was increased and was highly stimulated by insulin in muscle from adult rats. Our findings suggest that early postnatal undernutrition increases insulin sensitivity in adulthood, which appears to be directly related to changes in critical steps required for glucose metabolism.

Early life predictors of chronic disease

Many chronic diseases may have their seeds early in life. Observations from the Dutch famine have taught us that the intrauterine environment is an important determinant of adult health. Birth weight has been related to cardiovascular disease (CVD), hypertension, diabetes, and cancer. Critical phases for adult obesity development include time periods between conception and adolescence. A life course approach to chronic disease prevention includes the study of maternal diet during pregnancy, intrauterine exposures, postnatal growth, and the adolescent period.

Maternal protein restriction before pregnancy affects vital organs of offspring in Wistar rats

Epidemiologic studies indicate that undernutrition during fetal growth can have long-term effects on adult health. However, it is not known whether these effects are also associated with maternal undernutrition before conception. The objective of the present study was to examine the effect of dietary restriction before pregnancy on the vital organs and blood parameters of offspring at different time points. Wistar female rats in the restricted group were fed a diet consisting of 80 g protein/kg for 8 weeks before pregnancy and switched to 160 g protein/kg (control) from day 0 of pregnancy, while animals from the control group were fed 160 g protein/kg throughout life. The progeny were studied at birth (n = 71), at 94 days (n = 20), and at 180 days (n = 16). Weight gain during pregnancy was significantly lower (P <.01) for dams in the restricted group. At birth, relative weight for brain was lower (P </=.008), while for kidney it was higher (P </=.008) in the restricted group compared to control. At 94 days, the relative weights of brain, liver, and heart were lower (P </=.01 for all) in the restricted group than in the control group. However, at 180 days, only liver and kidney showed lower (P </=.01 for both) relative weights. Further, in the restricted group, increases in blood glucose at 94 days and in cholesterol at 180 days were significant (P <.01 for both) in the offspring. The results thus indicate that maternal undernutrition before conception not only affected growth of vital organs, but also resulted in increased levels of glucose and cholesterol in the offspring at adulthood.

Genetic effects of methylation diets

DNA methylation at cytosines in CpG dinucleotides can lead to changes in gene expression and function without altering the primary sequence of the DNA. Methylation can be affected by dietary levels of methyl-donor components, such as folic acid. This may be an important mechanism for environmentally induced changes in gene expression. Recent literature supports a role for DNA-methylation changes in a number of adult-onset disorders and during development. These changes may be significant for better understanding certain birth defects (e.g., neural tube defects) and the long-term consequences of early environmental influences on gene expression (metabolic programming). Optimal "methylation diets" should be investigated as part of the prevention and treatment of all these conditions, as well as in disorders such as Rett syndrome, whose primary defects may lie in DNA methylation-dependent gene regulation.

The "fetal origins" hypothesis: challenges and opportunities for maternal and child nutrition

The "fetal origins" hypothesis postulates that conditions, most likely nutritional, "program" the fetus for the development of chronic diseases in adulthood. Associations between the newborn's size at birth and various determinants or consequences of chronic diseases have been identified in many, but not all, of the available studies. It remains to be established whether these associations are causal. Remarkably little information is available on the specific role of maternal nutritional status. The role of birth weight remains difficult to interpret except as a proxy for events in intrauterine life. Unfortunately, birth weight does not make an important contribution to the population attributable risk of cardiovascular disease; lifestyle factors during adulthood make much greater contributions. Data from experimental species suggest possible mechanisms for the origin of chronic disease early in life. It is too soon to use this research as a basis for new interventions directed at pregnant women for the purpose of reducing chronic disease in their offspring.

Early nutrition and risk of disease in the adult

The differentiation of key metabolic systems that occurs during intrauterine life is greatly influenced by environmental nutritional conditions, which in turn are related to maternal nutritional status. In postnatal life, childhood exposure to slow-acting environmental factors, primarily through the diet, will begin to condition adult susceptibility to diseases. Examples of these dietary factors are intake of saturated fat, sodium, calcium, etc. For example, bone calcium accumulation during childhood and adolescence will be a major determinant of risk of osteoporosis later in life. Similarly, a high intake of saturated fat during childhood may promote the process of atherosclerosis in persons with genetic susceptibility, thus accelerating the clinical manifestations of coronary heart disease in adult life. These findings, although still not completely clarified, constitute a significant opportunity for preventive intervention. While preventive intervention in adult life may reduce risk, this is usually difficult and results are often limited. One example would be obesity. In contrast, interventions early in life, aimed at reducing these early risk factors, could potentially result in major reductions in the incidence of several diseases of adults.

Relation between birth weight at term and growth rate, skeletal age, and cortical bone at 6-11 years

There is an apparent link between fetal and childhood growth and puberty and risk for several degenerative diseases in adulthood. It is also important to consider associations between birth weight and indicators of growth and biological maturation during childhood and adolescence as potential explanations for associations between fetal growth and adult risk for disease. The present study examines the association between birth weight and (1) size attained and rate of growth in body size and cortical bone area of the second metacarpal (M II), and (2) skeletal age and rate of skeletal maturation in children 6-11 years of age. The sample included 127 boys and 105 girls of European ancestry, divided into two age groups, 6-8 years and 9-11 years. The relationship between birth weight and attained size (stature, mass, and the BMI), M II cortical area and skeletal age (SA, Tanner-Whitehouse method) during childhood was examined with correlational analyses. Observations on children measured on two occasions were converted to annual velocities, and correlations between birth weight and annual velocities were also calculated. Birth weight is significantly associated with stature and mass in boys and only with stature in girls 6-11 years of age, but is not related to the BMI, M II cortical area, or skeletal maturity. Birth weight is not significantly related to annual velocities of growth in stature, mass, the BMI and M II cortical area; to the annual increment in SA; and to weight gain from birth to the time of measurement (intervals of 6 to 11 years). The results emphasize a role of other influences than birth weight on growth rate, cortical area of M II, and skeletal maturation during childhood. Am. J. Hum. Biol. 11:505-511, 1999. Copyright 1999 Wiley-Liss, Inc.

A low-protein isocaloric diet during gestation affects brain development and alters permanently cerebral cortex blood vessels in rat offspring

In humans, low birth weight is associated with nonfatal stroke, cardiovascular disease and diabetes at adulthood. The aim of this study was to investigate in rats the effect of early protein restriction, inducing low birth weight, on brain and endocrine pancreas vascularization at birth and to study if such alterations lasted until adulthood. Pregnant rats were fed either 20 or 8% protein isocaloric diets. Control newborns were nursed by their dams fed the 20% protein diet and low protein (LP) pups by dams fed either the 8 or 20% protein diet. The diets given during lactation were maintained until adulthood. The blood vessel density of cerebral cortex analyzed by morphometry in 3-d-old pups from dams fed the 8% protein diet was lower than in control (C). It remained lower at adulthood whether a LP or a C diet was given postnatally. Reduction of vascularization at adulthood induced by the LP diet limited to fetal life seems characteristic for the brain since vascularization of islets of Langerhans was reduced in neonates but normalized at adulthood by a C diet postnatally. Body and brain weights were lower in LP pups and adults. DNA concentration was lower in forebrain and higher in cerebellum in LP pups. In brain of LP adults, DNA, protein, cholesterol and phospholipid concentrations were lower and were restored at adulthood by a normal diet after birth. In conclusion, cerebral cortex of offspring exposed to a LP isocaloric diet during fetal development showed reduced vascularization which remained throughout life.

Epidemiology of otitis media onset by six months of age

OBJECTIVE

Although early otitis media (OM) onset predicts later recurrent and chronic OM, little research has been directed at illuminating the role of prenatal exposures in early OM. This prospective study examined prenatal, innate, and early environmental exposures associated with acute otitis media (AOM) onset and recurrent OM (ROM) by age 6 months.

DESIGN AND METHODS

Prospective study of 596 infants from a health maintenance organization followed from birth to 6 months. Mothers completed monthly forms on prenatal exposures (diet, medications, and illnesses) and infant risk factors (eg, smoke exposure and child care) during pregnancy and until infants were 6 months old. Urine samples were collected when infants were 2 months of age and analyzed for cotinine and creatinine. Physicians and nurse practitioners examined infants at each clinic visit and completed standard ear examination forms.

RESULTS

Thirty-nine percent had an episode of AOM and 20% had ROM by age 6 months. Using Cox's regression models to control for confounding, respiratory tract infection (relative risk [RR] 7.5), day care (RR 1. 7), >1 sibling (RR 1.4), maternal, paternal, and sibling OM history (RR 1.6, 1.5, and 1.7, respectively) were significantly related to early OM onset. ROM was related to respiratory tract infection (RR 9. 5), day care (RR 1.9), conjunctivitis (RR 2.0), maternal OM history (RR 1.9), and birth in the fall (RR 2.6). Among prenatal exposures, only high prenatal dietary vitamin C intake was significantly inversely related to early AOM with univariate but not multivariate analysis.

CONCLUSION

Prenatal factors were not linked to early AOM onset with multivariate analysis, but environmental and innate factors play an important role in early AOM onset. Strategies to reduce exposure to environmental variables could reduce rates of early AOM, which could potentially result in declining rates of ROM and chronic OME.

Potential mechanisms of metabolic imprinting that lead to chronic disease

This review synthesizes a subset of human epidemiologic and experimental animal studies that suggest that early nutrition affects susceptibility to chronic diseases in adulthood. These studies provide evidence that biological mechanisms may exist to "memorize" the metabolic effects of early nutritional environments. However, hypothesis-driven investigations of potential mechanisms have been scant. Thus, our understanding of the biology underlying metabolic imprinting is incomplete. A working definition of metabolic imprinting is proposed, emphasizing the adaptive nature and limited ontogenic window of the mechanisms putatively responsible for these relations. Five specific candidate mechanisms of metabolic imprinting are elaborated: 1) induced variations in organ structure, 2) alterations in cell number, 3) clonal selection, 4) metabolic differentiation, and 5) hepatocyte polyploidization. Last, experimental approaches for probing potential mechanisms with animal models are discussed.

Role of the prenatal environment in the development of obesity

Establishing that prenatal life is a critical or sensitive period for the development of obesity may focus basic research and clinical prevention efforts on this period. This review summarizes evidence that the intrauterine environment influences the risk of later obesity and considers the mechanisms by which this may occur. The association between birth weight and adult weight suggests that there are enduring effects of the intrauterine environment on later obesity risk. We examine whether the maternal factors of diabetes, obesity, and pregnancy weight gain alter the intrauterine environment and thereby increase the risk of later obesity in the offspring. Of these maternal factors, evidence is strongest for the role of maternal diabetes. No single mechanism explains how these maternal factors could change the intrauterine environment to increase obesity risk. However, all potential mechanisms involve an altered transfer of metabolic substrates between mother and fetus, which may influence the developing structure or function of the organs involved in energy metabolism.

[Long-term consequences of fetal nutrition]

A large number of animal experimental data indicate that pre- or early postnatal malnutrition can have long-term negative consequences on weight and height, with smaller weight and height in adulthood than predicted on genetics basis. Furthermore, according to the Barker's hypothesis, based on data available from British cohort studies, in utero malnutrition could also result in an increased risk of cardiovascular, endocrine and metabolic diseases in adulthood. There are however discordant data in the literature which invite to be cautious about on this hypothesis, mainly because the role of the socio-economic factors during childhood and adulthood have not been taken into account.