Fishing in the stream of diabetes: from measuring insulin to the control of fetal organogenesis

Long-term programming of blood pressure by maternal dietary iron restriction in the rat

We have reported that blood pressure was elevated in 3-month-old rats whose mothers were Fe-restricted during pregnancy. These animals also had improved glucose tolerance and decreased serum triacylglycerol. The aim of the present study was to determine whether these effects of maternal nutritional restriction, present in these animals at 3 months of age, can be observed in the same animals in later life. Pulmonary and serum angiotensin converting enzyme (ACE) concentrations were also measured to investigate whether the renin-angiotensin system was involved in the elevation of blood pressure observed in the offspring of Fe-restricted dams. Systolic blood pressure was higher in the offspring of Fe-restricted dams at 16 months of age. Heart and kidney weight were increased as a proportion of body weight in the offspring of Fe-restricted dams. The pulmonary ACE concentration was not significantly different between the groups. The serum ACE concentration was significantly elevated in the offspring of Fe-restricted dams at 3 but not 14 months of age. There was a strong correlation between serum ACE levels at 3 and 14 months of age. Glucose tolerance and serum insulin were not different between the maternal diet groups. Serum triacylglycerol tended to be lower in the offspring of Fe-restricted dams. There were no differences in serum non-esterified fatty acids or serum cholesterol between the maternal diet groups. This study provides further evidence that maternal nutrition has effects on the offspring that persist throughout life. At 16 months of age, the elevation of blood pressure in Fe-restricted offspring does not appear to be mediated via changes in ACE levels. Both cardiac hypertrophy and decreased serum triacylglycerol have also been observed in Fe-restricted fetuses, suggesting that these changes may be initiated in utero.

The mammary gland in mammalian evolution: a brief commentary on some of the concepts

Current thinking is highlighting the mammary glands and the process of lactation in the evolutionary success of mammals over and above the selective advantages provided by the nutritional and antimicrobial properties of milk. The extended period of contact between mothers and their young, necessitated by the regular and frequent transfer of milk, particularly characteristic of the primate strategy of reproduction and the primate mode of life, has been suggested to afford the offspring the opportunity for more learning and the eventual development of the levels of intelligence present in "higher" primates. Lactation offers the opportunity for maternal effects on development and the eventual phenotype of the offspring in addition to those that occur during pregnancy or from behavioral interactions. Lactation comes with high metabolic costs, which are manifested in parent-offspring conflict, and special physiological adaptations have evolved which match milk supply to demand by the young.

A reconsideration of the origins of the type 2 diabetes epidemic among Native Americans and the implications for intervention policy

Type 2 diabetes has reached epidemic proportions in many Native American communities in North America. The overwhelming majority of physicians, biomedical researchers, and medical ecologists continue to explain the astoundingly high prevalence rates of diabetes among Native Americans and other high prevalence populations in terms of yet-to-be-identified genetic factors. Recent experimental and epidemiological research, however, has brought to light an etiological alternative to the genetic-predisposition model. This body of research suggests that type 2 diabetes may result initially from fetal malnutrition and, in subsequent generations, be propagated via perturbations in the intrauterine environment. Native American populations at greatest risk for diabetes today are the ones most likely to have endured severe nutritional stress in their recent histories, thus experiencing the conditions that are most conducive to the diabetic developmental sequence. If further substantiated, the implications of the fetal-origin model of diabetes for diabetes intervention programs are profound.

Pancreatic islet insulin secretion and metabolism in adult rats malnourished during neonatal life

Pancreatic islets were isolated from rats that had been nursed by dams fed with a control or an 8.7% protein diet during the first 12 d of the lactation period. Glucose-induced insulin secretion from islets in the 8.7% protein group was reduced 50%. The islet insulin and DNA content were similar, whereas the pancreatic insulin content was reduced by 30 % in the rats fed 8.7 % protein. In order to elucidate the mechanism responsible for the attenuation of insulin secretion, measurements were performed of the activity of several islet enzymes that had previously been supposed to be involved in the coupling of glucose stimulation to insulin secretion. Islet glucose oxidation was unaffected, but glucose-stimulated hydrolysis of phosphatidylinositol was reduced by one-third in the islets of rats fed 8.7% protein. The activity of mitochondrial glycerophosphate dehydrogenase was similar in islets of rats fed the 8.7% protein diet and those fed the control diet. The activity of Ca-independent phospholipase A2 was increased fourfold in the islets of rats fed 8.7% protein. It is concluded that impairment of glucose-induced insulin secretion in rats fed a low-protein diet may be caused by attenuation of islet phosphatidylinositol hydrolysis, and it is tentatively suggested that the increased activity of Ca-independent phospholipase A2 in islets of rats fed a low-protein diet may participate in the stimulation of apoptosis.

Complex adaptive systems, aging and longevity

Mortality and reproduction are intimately entwined in the study of aging and longevity. I apply the modern theory of complex adaptive systems (nonlinear, stochastic, dynamic methods) to questions of aging and longevity. I begin by highlighting major questions that must be answered in order to obtain a deeper understanding of aging. These are: (i) What should (in an evolutionary sense) mortality trajectories look like? (ii) Why does caloric restriction slow aging? (iii) Why does reproduction cause delayed mortality? (iv) Why does compensatory growth cause delayed mortality? I show how dynamic state variable models based on stochastic dynamic programming (Clark & Mangel, 2000) can be used to embed genetic theories of senescence (either mutation accumulation or antagonistic pleiotropy) in the somatic environment, as George Williams called for in 1957, and how they make the disposable soma theory of aging operational. Such models will allow unification of genetic and phenotypic theories of aging.

Programming of intermediary metabolism

Studies of animal models were carried out to explore mechanisms that might underlie epidemiological findings linking indices of poor early (fetal and early postnatal) growth to an increased risk of developing poor glucose tolerance, including the metabolic syndrome, in adult life. Adult obesity was also seen to play an important role in adding to these risks. We proposed the 'thrifty phenotype' hypothesis to provide a conceptual and mechanistic framework that could be tested by experimentation in animal models. Our main approach has been to feed a reduced protein diet to pregnant and/or lactating rat dams as a means of reducing growth in the fetal and/or preweaning stages of pup growth. Animals were weaned onto either a normal diet or an obesity-inducing highly palatable, cafeteria-style diet. Alterations in intermediary metabolism were noted in the rats with early growth restriction, which provide support for our hypothesis and clues to the mechanism.

Enhanced glucose uptake into adipose tissue induced by early growth restriction augments excursions in plasma leptin response evoked by changes in insulin status

OBJECTIVE

The study used a rat model of moderate protein restriction exclusively during fetal and early neonatal life, which has been established to cause intrauterine early growth retardation, to investigate possible association between adipocyte glucose utilisation and leptin secretion in vivo.

DESIGN

These rats, termed early protein restricted, were transferred to a diet containing the standard amount of protein at weaning and remained on this diet til adulthood, at which time adipocyte glucose utilisation and leptin secretion was compared with that of age-matched controls. Insulin status was modulated by acute (2 h) insulin infusion at a constant rate (4.2 mU/min per kg) to elevate insulin to the high physiological range. Euglycaemia was maintained by variable glucose infusion.

MEASUREMENTS

Glucose utilisation was measured in vivo in conscious unrestrained rats using 2-deoxy[1-3H] glucose. Leptin concentrations (measured by radioimmunoassay) and whole-body glucose kinetics (measured using [3-3H] glucose) were studied in the postabsorptive state and after acute insulin stimulation.

RESULTS

Adipose-tissue glucose utilisation rates in vivo tended to be higher in the post-absorptive state and were consistently 1.8-3.0-fold higher after insulin stimulation in the early-protein-restricted group compared with the control group. Both the absolute increase in leptin concentration elicited by hyperinsulinaemia and the magnitude of the effect of insulin to elevate plasma leptin levels were greater in the early-protein-restricted group compared with the control group (by 2.2-fold and 1.6-fold, respectively). The effect of insulin to stimulate R(d) was much greater in the early-protein-restricted group (4.1-fold) than in the control group (2.2-fold) and the absolute increase in R(d) elicited by insulin was 43% higher in the early-protein-restricted group than in the control group.

CONCLUSIONS

It is concluded that poor early growth enhances the acute leptin response to changes in insulin status through programmed changes in adipocyte glucose handling.

Fetal programming of cardiovascular function through exposure to maternal undernutrition

A substantial and robust body of epidemiological evidence indicates that prenatal dietary experience may be a factor determining cardiovascular disease risk. Retrospective cohort studies indicate that low birth weight and disproportion at birth are powerful predictors of later disease risk. This prenatal influence on non-communicable disease in later life has been termed programming. Maternal nutritional status has been proposed to be the major programming influence on the developing fetus. The evidence from epidemiological studies of nutrition, fetal development and birth outcome is, however, often weak and inconclusive. The validity of the nutritional programming concept is highly dependent on experimental studies in animals. The feeding of low-protein diets in rat pregnancy results in perturbations in fetal growth and dimensions at birth. The offspring of rats fed low-protein diets exhibit a number of metabolic and physiological disturbances, and are consistently found to have high blood pressure from early postnatal life. This experimental model has been used to explore potential mechanisms of programming through which maternal diet may programme the cardiovascular function of the fetus. Indications from this work are that fetal exposure to maternally-derived glucocorticoids plays a key role in the programming mechanism. Secondary to this activity, the fetal hypothalamic-pituitary-adrenal axis may stimulate renin-angiotensin system activity, resulting in increased vascular resistance and hypertension.

Adult survival after prenatal exposure to the Dutch famine 1944--45

Early life events may affect adult survival. We studied the effect of prenatal exposure to the Dutch famine 1944--45 on survival among 2254 people born in Amsterdam. Mortality up to age 50 was highest among those born before the famine (15.2%) and among those exposed to famine in late gestation (14.6%). It was lower among those exposed in mid- (11.2%) or early gestation (11.5%), and was lowest among those conceived after the famine (7.2%). These differences were caused by effects on mortality in the first year after birth and were mainly related to nutrition and infections. There was no effect of exposure to famine on mortality after the age of 18. The hazard ratio was 1.4 [0.8, 2.3] for those born before the famine, 1.1 [0.5, 2.3] for those exposed in late gestation, 0.8 [0.3, 1.8] for those exposed in mid-gestation and 1.1 [0.5, 2.5] in those exposed in early gestation compared with those conceived after the famine. We could not demonstrate effects of prenatal exposure to famine on cause-specific mortality after the age of 18. Because prenatal exposure to famine is linked to cardiovascular risk factors and disease, increased cardiovascular mortality in the future may be expected.

Impaired PI 3-kinase activation in adipocytes from early growth-restricted male rats

Epidemiological studies have established a relationship between early growth restriction and subsequent development of type 2 diabetes. Animal studies have shown that offspring of protein-restricted rats undergo a greater age-related loss of glucose tolerance than controls. The aim of this study was to investigate the possibility that this deterioration of glucose tolerance is associated with changes in adipocyte insulin action. Adipocytes from low-protein offspring had higher basal levels of glucose uptake than controls. Insulin stimulated glucose uptake into control adipocytes but had little effect on low-protein adipocytes. Both groups had similar levels of basal and isoproterenol-stimulated lipolysis. Insulin inhibited lipolysis in control adipocytes but had a reduced effect on low-protein adipocytes. These changes in insulin action were not related to altered expression of insulin receptors or insulin receptor tyrosine phosphorylation; however, they were associated with reduced phosphatidylinositol 3-kinase and protein kinase B activation. These results demonstrate that reduced glucose tolerance observed in late adult life after early growth restriction is associated with adipocyte insulin resistance.

Metabolic programming in animals

A large number of epidemiological studies have revealed that there is a relationship between early growth restriction and the subsequent development of type 2 diabetes or the metabolic syndrome. The mechanistic basis of this relationship and the relative roles played by genes and the environment remains the subject of much current debate. Animal models of early growth restriction have been developed in an attempt to understand its relationship with adult disease and to provide insight into the underlying molecular mechanisms. These models show many features of the metabolic syndrome. In the maternal protein restriction model, insulin resistance and hypertension is observed. The uterine artery ligation model shows obesity in adulthood. This provides strong evidence that alterations in the fetal environment can lead to diabetes in adult life.

Intra-uterine programming of the endocrine pancreas

In altricial species such as the rat and mouse, there is good evidence for the intra-uterine programming of the endocrine pancreas. Changes in the intra-uterine nutritional environment cause alterations in the structure and function of the islets which have life-long effects and predispose the animal to glucose intolerance and diabetes in later life. In rodents, the islets develop relatively late in gestation and undergo substantial remodelling in the period immediately after birth. Hence, the critical window for islet development in these animals is short and readily accessible for experimental manipulation. The short life-span of these species also means that elderly animals can be studied within a reasonable time frame. In precocious species, such as guinea pigs and farm animals, intra-uterine programming of the endocrine pancreas is less well established. In part, this may be due to difficulties in identifying the critical window for development as islet formation and remodelling begin at an earlier stage of gestation and continue for longer after birth. The long life-span of these animals and the relative insulin resistance of adult ruminants compared to other species also make it difficult to establish whether fetal changes in islet development have long-term consequences. In the human, the main phase of islet development occurs during the second trimester, although remodelling occurs throughout late gestation and early childhood. There is, therefore, a relatively long period in which early changes in islet development could be reversed or ameliorated in the human. Although the human epidemiological observations suggest that the fetal origin of adult glucose intolerance is due primarily to changes in insulin sensitivity rather than to defective insulin secretion, subtle changes in islet morphology and function sustained in utero may well contribute to the increased susceptibility to type 2 diabetes observed in adults who were growth-retarded in utero.

The thrifty phenotype hypothesis

The thrifty phenotype hypothesis proposes that the epidemiological associations between poor fetal and infant growth and the subsequent development of type 2 diabetes and the metabolic syndrome result from the effects of poor nutrition in early life, which produces permanent changes in glucose-insulin metabolism. These changes include reduced capacity for insulin secretion and insulin resistance which, combined with effects of obesity, ageing and physical inactivity, are the most important factors in determining type 2 diabetes. Since the hypothesis was proposed, many studies world-wide have confirmed the initial epidemiological evidence, although the strength of the relationships has varied from one study to another. The relationship with insulin resistance is clear at all ages studied. Less clear is the relationship with insulin secretion. The relative contribution of genes and environment to these relationships remains a matter of debate. The contributions of maternal hyperglycaemia and the trajectory of postnatal growth need to be clarified.

Animal models and programming of the metabolic syndrome

The purpose of this review is to consider how current animal models of fetal programming contribute to knowledge of the metabolic syndrome in adult humans. Low birth weight infants have an increased risk of developing cardiovascular and coronary heart disease, hypertension, diabetes and stroke in adulthood. A number of animal studies confirm the association between events during fetal life and subsequent adult disease. This review considers how these have contributed to our understanding of this relationship, and how they may help to uncover the underlying mechanisms. The importance of dietary, pharmacological, genetic and surgical models is assessed, and their usefulness in the prevention of human disease evaluated. Although progress has been made, further investigations using animals are needed to clarify the mechanisms involved in the programming of adult disease. Once these processes are understood, it may be possible to identify and protect at-risk individuals.

Coronary heart disease after prenatal exposure to the Dutch famine, 1944-45

OBJECTIVE

To assess the effect of prenatal exposure to maternal malnutrition on coronary heart disease in people born around the time of the Dutch famine, 1944-45.

DESIGN

Historical cohort study.

SETTING

Community study.

PATIENTS

Singletons born alive between November 1943 and February 1947 for whom detailed birth records were available.

DESIGN

The prevalence of coronary heart disease was compared between those exposed to famine in late gestation (n = 120), in mid-gestation (n = 108), or in early gestation (n = 68), and those born in the year before the famine or those conceived in the year after the famine (non-exposed subjects, n = 440).

MAIN OUTCOME MEASURES

Prevalence of coronary heart disease, defined as the presence of angina pectoris according to the Rose questionnaire, Q waves on the ECG, or a history of coronary revascularisation.

RESULTS

The prevalence of coronary heart disease was higher in those exposed in early gestation than in non-exposed people (8.8% v 3.2%; odds ratio adjusted for sex 3.0, 95% confidence interval (CI) 1.1 to 8.1). The prevalence was not increased in those exposed in mid gestation (0.9%) or late gestation (2.5%). People with coronary heart disease tended to have lower birth weights (3215 g v 3352 g, p = 0.13), and smaller head circumferences at birth (32.2 cm v 32.8 cm, p = 0.05), but the effect of exposure to famine in early gestation was independent of birth weight (adjusted odds ratio 3.2, 95% CI 1.2 to 8.8).

CONCLUSIONS

Although the numbers are very small, this is the first evidence suggesting that maternal malnutrition during early gestation contributes to the occurrence of coronary heart disease in the offspring.

Impaired glucose tolerance and elevated blood pressure in low birth weight, nonobese, young south african adults: early programming of cortisol axis

Low birth weight is associated with increased cardiovascular and metabolic disorders in adult life, although the mechanisms of this effect remain uncertain. There is one report of increased morning plasma cortisol levels in an elderly low birth weight cohort, but whether this is primary or secondary to other aspects of the phenotype is unclear. We investigated the association between low birth weight and glucose intolerance, blood pressure, and dyslipidemia in young, nonobese adults from a community undergoing the health transition with a high prevalence of both noncommunicable diseases and low birth weight. Additionally, we investigated whether altered basal and stimulated cortisol levels as a marker of hypothalamic-pituitary-adrenal responsiveness or cortisol metabolism were associated with low birth weight in these young adults. Twenty-year-old, historically disadvantaged, urbanized South Africans (n = 137) with birth weights either below the 10th percentile [underweight for age (UFA)] or between the 25th and 75th percentiles [appropriate for gestational age (AFA)] had anthropometry, blood pressure, lipid levels, and glucose tolerance measured. In a subset (n = 62), 0900 h plasma cortisol concentrations, cortisol responses to 1 microg ACTH, and urinary glucocorticoid metabolites were measured. The mothers of UFA infants were themselves lighter and had a lower body mass index (P: = 0. 0016). At age 20 yr, although the UFA group was still smaller and lighter, with a lower body mass index, they had higher fasting plasma glucose levels (P: = 0.047), and a greater proportion demonstrated glucose intolerance (11.9% vs. 0%; P: < 0.01). The UFA group also had higher systolic [UFA, 126.0 +/- 13.3 (+/-SD); AFA, 122.0 +/- 11.7 mm Hg; P: = 0.007] and diastolic (72.3 +/- 8.4 vs. 69. 5 +/- 8.7 mm Hg; P: = 0.02) blood pressures, after covarying for current weight and gender. Plasma cortisol levels determined at 0900 h were higher in the UFA group (484.9 +/- 166.3 vs. 418.6 +/- 160.6 nmol/L) and showed a greater plasma cortisol response to low dose ACTH stimulation (area under the curve for cortisol: UFA, 77,238 +/- 19,511; AFA, 66,597 +/- 16,064 nmol/L.min; P: = 0.04). In conclusion, the link between low birth weight and adult glucose intolerance and blood pressure elevation occurs in young adults in a high risk, disadvantaged population despite a lack of full catch-up growth. Moreover, cortisol axis activation is an early feature in the process linking low birth weight with adult cardiovascular and metabolic disease and is not dependent upon adult obesity or full catch-up growth, at least in this population undergoing the health transition.

Catecholamine levels and receptor expression in low protein rat offspring

AIMS

Low birthweight in humans has been shown to lead to increased resting pulse rate in adult life, suggesting possible increased sympathoadrenal activity. The hypothesis that early growth restriction is associated with permanent alterations in catecholamine metabolism was tested.

METHODS

Circulating catecholamine concentrations (by radioimmunoassay) and adipocyte adrenoceptor expression from different fat depots (by Western blot) were estimated in 12-week-old male offspring of rat dams fed a reduced protein diet during pregnancy and lactation.

RESULTS

In the fed state, median (interquartile range) plasma adrenaline concentrations for male control and low protein offspring rats were: 0.65 (0.48-0.86) vs. 1.42 (0.89-1.87) nmol/l (P < 0.005), respectively. Equivalent noradrenaline concentrations were: 2.71 (2.16-3.46) vs. 3.45 (3.00-4.28) nmol/l (P < 0.05). After 24 h starvation, plasma adrenaline concentrations of controls rose to become similar to those of low protein offspring: 1.03 (0.95-1.31) vs. 1.41 (0.69-1.62) nmol/l (P = 0.3), respectively. Noradrenaline concentrations rose in both groups to become similar: 3.84 (3.33-4.54) vs. 4.32 (3.70-6.54) nmol/l (P = 0.3). In epididymal adipocytes adrenoceptor expression (relative to that of controls) was: alpha2A 0.79 (0.66-0.94) (P = 0.08), beta1 2.60 (2.27-3.07) (P = 0.04), beta3 1.37 (1.27-1.46) (P = 0.02). Similar-pattern differences in adrenoceptor expression were observed in subcutaneous and intra-abdominal adipocytes.

CONCLUSIONS

These results are consistent with the suggestion that long-term alterations in catecholamine metabolism are present in adult offspring of rats fed a reduced protein diet during pregnancy and lactation.

Plasma fibrinogen and factor VII concentrations in adults after prenatal exposure to famine

To assess the effect of maternal malnutrition during different stages of gestation on plasma concentrations of fibrinogen and factor VII, we investigated 725 people, aged 50 years, born around the time of the Dutch famine 1944-5. After adjustment for sex, plasma fibrinogen concentrations differed by -0.01 g/l (95% confidence interval, -0.14-0.11) in those exposed in late gestation, by -0.03 g/l (-0.16-0.11) in those exposed in mid gestation, and by 0.13 g/l (-0.03-0.30) in those exposed in early gestation, compared with non-exposed people (those born before and those conceived after the famine pooled together). Plasma factor VII concentrations differed by 0.4% (-5.4% to 6.6%) in those exposed to famine in late gestation, by 1.5% (-4.6% to 8.1%) in those exposed in mid gestation. and by -11.8% (-18.4 to -4.8%) in those exposed in early gestation, compared with nonexposed people. Size at birth was not associated with plasma concentrations of fibrinogen or factor VII. Our finding that factor VII concentrations were significantly lower in people whose mothers had been exposed to famine in early pregnancy suggests that liver function may be affected by undernutrition in early gestation.

Nutrition, oxidative damage, telomere shortening, and cellular senescence: individual or connected agents of aging?

There is substantial and long-standing literature linking the level of general nutrition to longevity. Reducing nutrition below the amount needed to sustain maximum growth increases longevity in a wide range of organisms. Oxidative damage has been shown to be a major feature of the aging process. Telomere shortening is now well established as a key process regulating cell senescence in vitro. There is some evidence that the same process may be important for aging in vivo. Very recently it has been found that oxidative damage accelerates telomere shortening. It is therefore possible for us to propose as an outline hypothesis that the level of nutrition determines oxidative damage which in turn determines telomere shortening and cell senescence and that this pathway is important in determining aging and longevity in vivo. We also propose that telomeres in addition to their well-recognized role in "counting" cell divisions are also, through their GGG sequence, important monitors of oxidative damage over the life span of a cell. This may explain the evolutionary conservations of this triplet in the repeat telomere sequence unit.

Early-life programming of susceptibility to dysregulation of glucose metabolism and the development of Type 2 diabetes mellitus

There is increasing epidemiological evidence in humans which associates low birthweight with later metabolic disorders, including insulin resistance and glucose intolerance. There is evidence that nutritional and hormonal factors (e.g. maternal protein restriction, exposure to excess maternal glucocorticoids) markedly influence intra-uterine growth and development. A picture is also emerging of the biochemical and physiological mechanisms that may underlie these effects. This review focuses on recent research directed towards understanding the molecular basis of the relationship between indices of poor early growth and the subsequent development of glucose intolerance and Type 2 diabetes mellitus using animal models that attempt to recreate the process of programming via an adverse intra-uterine or neonatal environment. Emphasis is on the chain of events and potential mechanisms by which adverse adaptations affect pancreatic-beta-cell insulin secretion and the sensitivity to insulin of key metabolic processes, including hepatic glucose production, skeletal-muscle glucose disposal and adipose-tissue lipolysis. Unravelling the molecular details involved in metabolic programming may provide new insights into the pathogenesis of impaired glucoregulation and Type 2 diabetes.

In utero programming of cardiovascular disease

Low birth weight, thinness and short body length at birth are now known to be associated with increased rates of cardiovascular disease and non-insulin dependent diabetes in adult life. The fetal origins hypothesis proposes that these diseases originate through adaptations which the fetus makes when it is undernourished. These adaptations may be cardiovascular, metabolic or endocrine. They permanently change the structure and function of the body. Prevention of the diseases may depend on prevention of imbalances in fetal growth or imbalances between pre- and post-natal growth, or imbalances in nutrient supply to the fetus.

Restricted fetal growth and the response to dietary cholesterol in the guinea pig

Epidemiological studies suggest that retarded growth before birth is associated with increased plasma total and low-density lipoprotein (LDL) cholesterol concentrations in adult life. Thus perturbations of prenatal growth may permanently alter cholesterol metabolism. To determine directly whether restriction of prenatal nutrition and growth alters postnatal cholesterol homeostasis, the plasma cholesterol response to cholesterol feeding (0.25% cholesterol) was examined in adult guinea pig offspring of ad libitum-fed or moderately undernourished mothers. Maternal undernutrition (85% ad libitum intake throughout pregnancy) reduced birth weight (-13%). Plasma total cholesterol was higher prior to and following 6 wk cholesterol feeding in male offspring of undernourished mothers compared with male offspring of ad libitum-fed mothers (P < 0.05). The influence of birth weight on cholesterol metabolism was examined by dividing the offspring into those whose birth weight was above (high) or below (low) the median birth weight. Plasma total cholesterol concentrations prior to cholesterol feeding did not differ with size at birth, but plasma total and LDL cholesterol were 31 and 34% higher, respectively, following cholesterol feeding in low- compared with high-birth weight males (P < 0.02). The response to cholesterol feeding in female offspring was not altered by variable maternal nutrition or size at birth. Covariate analysis showed that the effect of maternal undernutrition on adult cholesterol metabolism could be partly accounted for by alterations in prenatal growth. In conclusion, maternal undernutrition and small size at birth permanently alter postnatal cholesterol homeostasis in the male guinea pig.

Effect of intrauterine growth restriction on blood pressure, glucose tolerance and sympathetic nervous system activity in the rat at 3-4 months of age

OBJECTIVE

Epidemiological studies suggest that intrauterine growth restriction (IUGR) due to maternal undernutrition during pregnancy represents a major risk factor for hypertension and diabetes in adult age. However, placental insufficiency, rather than maternal malnutrition, is the main cause of IUGR in the Western world. We therefore studied the relationship between birth weight and adult blood pressure and glucose tolerance in an established animal model of placental insufficiency.

DESIGN

IUGR was induced by uterine artery ligation in pregnant rats and the offspring were studied at 3-4 months of age.

METHODS

In one subgroup of animals (n = 41, birth weight range 3.2-6.6 g) blood pressure was recorded over 72 h using telemetry and hypothalamic tissue levels of noradrenaline was measured. In another subgroup (n = 30, birth weight range 3.0-6.8 g) the activity of the sympathetic nervous system (SNS) was assessed by noradrenaline isotope dilution techniques and glucose tolerance determined by an intravenous glucose load.

RESULTS

Adult blood pressure was independent of birth weight Haemodynamic responses of IUGR rats to moderate sound stress was unaltered. In male rats neither SNS activity, hypothalamic noradrenaline concentrations nor glucose tolerance was associated with birth weight In contrast, IUGR in female rats was associated with increased SNS activity, elevated fasting blood glucose as well as lower insulin and higher glucose levels in response to a glucose load.

CONCLUSION

IUGR is not linked to an elevated blood pressure at 3-4 months of age in this model. However, in female rats, IUGR is associated with increased SNS activity and impaired glucose tolerance in adult life.

Sir David Cuthbertson Medal Lecture. The impact of dietary protein restriction on insulin secretion and action

The goal of this review is to develop the hypothesis, and review the evidence, that protein restriction, through synergistic effects on multiple organ systems predisposes to loss of normal regulation of fuel homeostasis that plays the central role in the development of type 2 (non-insulin-dependent) diabetes mellitus. The ability of insulin to regulate glucose production and disposal varies between individuals. These differences, together with the various compensatory mechanisms that are invoked to attempt to normalize fuel homeostasis, are of fundamental importance in the development and clinical course of type 2 diabetes mellitus. Protein deprivation impacts on both insulin secretion and insulin action. These effects may persist even when a diet containing adequate protein is presented subsequently. Data are presented that suggest that protein restriction results in an impaired ability of pancreatic beta-cells to compensate adequately for the defect in insulin action in insulin-resistant individuals. This persistent impairment of insulin secretion resulting from protein restriction predisposes to loss of glucoregulatory control and impaired insulin action after the subsequent imposition of a diabetogenic challenge. This inability to maintain the degree of compensatory hyperinsulinaemia necessary to prevent loss of glucose tolerance may have relevance to the increased incidence of diabetes on changing from a nutritionally-poor diet to a Western diet, and to the hypothesis that some cases of type 2 diabetes in adulthood may be related to poor early nutrition.

Lactate and glycerol release from subcutaneous adipose tissue in black and white lean men

To measure interstitial glycerol and lactate production from the sc adipose tissue of two regions in nine black and nine white lean men, sc microdialysis was performed in combination with adipose tissue blood flow rates measured with 133Xe clearance. In the postabsorptive state, the plasma glucose and insulin levels of the black men and white men were similar. The black men had higher plasma free fatty acids (825+/-97 vs. 439+/-58 micromol/L; P < 0.005), glycerol (99.5+/-5.1 vs. 54.1+/-3.3 micromol/L; P < 0.0001), and lactate (1056+/-95 vs. 729+/-45 micromol/L; P < 0.01). Interstitial glycerol concentrations in the black and white men were 227 vs. 163 micromol/L (P < 0.01) and 230 vs. 162 micromol/L (P < 0.05) in the abdominal and femoral regions. The adipose tissue blood flow rate was higher in the black men in the abdominal (7.9+/-0.9 vs. 3.1+/-0.5 mL/100 g x min; P < 0.01) and femoral area (5.2+/-0.6 vs. 2.8+/-0.3; P < 0.01). Interstitial lactate concentrations in black and white men were 1976 vs. 1364 micromol/L (P < 0.004) and 1953 vs. 1321 micromol/L (P < 0.004) in the abdominal and femoral regions, respectively. Glycerol release was higher in black men vs. white men for abdominal (0.21+/-0.02 vs. 0.14+/-0.02 micromol/100 g x min; P < 0.02) and femoral (0.22+/-0.02 vs. 0.15+/-0.01; P < 0.05) areas. Postprandially, black men had higher plasma glucose levels [1 h, 9.6+/-0.4 vs. 8.2+/-0.5 mmol/L (P < 0.05); 2 h, 8.9+/-0.4 vs. 7.2+/-0.4 mmol/L (P < 0.01)], but lower plasma insulin levels [1 h, 173+/-13 vs. 264+/-48 pmol/L (P < 0.05); 2 h, 136+/-20 vs. 209+/-34 pmol/L (P < 0.05)]. Plasma free fatty acid, lactate, and glycerol levels remained higher in the black men. After 1 h, lactate release was higher in the black men vs. that in the white men for abdominal (20.5+/-1.6 vs. 14.7+/-2.5 micromol/100 g x min;P < 0.05) and femoral (15.6+/-1.1 vs. 12.1+/-1.8; P < 0.03) areas. We conclude that the black men, who are relatively insulinopenic postprandially, have a brisker lipolysis and also release more lactate from sc fat tissue than white men. These differences in adipose tissue metabolism may be related to differences in the lipid profiles and glucose metabolism previously documented in these ethnic groups.

The long-term consequences of intra-uterine protein malnutrition for glucose metabolism

Our initial observations, in epidemiological studies, linking indices of poor early (fetal and infant) growth to the subsequent development of poor glucose tolerance and the insulin resistance syndrome in adult life, have been confirmed in studies in a wide variety of populations around the world. These findings led us 5 years ago to propose the 'thrifty phenotype' hypothesis. Tests of this hypothesis in an animal model in which the pregnant and/or lactating rat dams are fed on an isoenergetic diet containing just under half the normal protein content are consistent with the ideas put forward. They have also allowed us to refine the hypothesis in the light of the new data as follows: (1) the growth of the fetus (and possibly infant) is quantitatively and qualitatively altered by its nutritional environment (which may include maternal diet-dependent changes in maternal hormones); (2) these changes serve to select between the growth rates of different tissues according to priorities which differ between males and females (nutritional thrift) and to alter organ function to constitute a thrifty offspring adapted to survival in poor nutritional circumstances (thrifty phenotype); (3) an individual so constituted suffers adverse consequences in adult life if he/she experiences good or supranormal nutrition; (4) both poor insulin secretion and insulin resistance can result from these adaptive processes; (5) the adverse consequences include loss of glucose tolerance and hypertension. The precise outcome of growth retardation during early life may vary according to the type and timing of the factors responsible for the retardation. It remains to be determined to what extent these potentially adverse effects can be delayed or prevented by a suitable postnatal diet. Experiments in animal models are largely consistent with the concepts proposed from human epidemiological studies. They show that the metabolism of the liver, muscle and adipose tissue may be programmed by maternal nutrition during gestation and lactation. The combination of early growth restriction and subsequent adult obesity reproduced in the rat are the main features of the insulin resistance syndrome.

Early growth determines longevity in male rats and may be related to telomere shortening in the kidney

Maternal protein undernutrition can influence the growth and longevity of male offspring in the rat. We tested the hypothesis that these differences in longevity were associated with changes in the rate of telomere shortening. We found age-related shortening of telomeres in the liver and kidney but not in the brain of male rats. Growth retardation in postnatal life was associated with significantly longer kidney telomeres and an increased longevity. Conversely, growth retardation during the foetal life followed by postnatal catch-up growth was associated with a shorter life span and shorter kidney telomeres. These findings may provide a mechanistic basis for epidemiological studies linking early growth retardation to adult degenerative diseases.

Catch-up growth in childhood and death from coronary heart disease: longitudinal study

OBJECTIVE

To examine whether catch-up growth during childhood modifies the increased risk of death from coronary heart disease that is associated with reduced intrauterine growth.

DESIGN

Follow up study of men whose body size at birth was recorded and who had an average of 10 measurements taken of their height and weight through childhood.

SETTING

Helsinki, Finland.

SUBJECTS

3641 men who were born in Helsinki University Central Hospital during 1924-33 and who went to school in Helsinki.

MAIN OUTCOME MEASURES

Hazard ratios for death from coronary heart disease.

RESULTS

Death from coronary heart disease was associated with low birth weight and, more strongly, with a low ponderal index at birth. Men who died from coronary heart disease had an above average body mass index at all ages from 7 to 15 years. In a simultaneous regression the hazard ratio for death from the disease increased by 14% (95% confidence interval 8% to 19%; P<0.0001) for each unit (kg/m3) decrease in ponderal index at birth and by 22% (10% to 36%; P=0.0001) for each unit (kg/m2) increase in body mass index at 11 years of age. Body mass index in childhood was strongly related to maternal body mass index, which in turn was related to coronary heart disease. The extent of crowding in the home during childhood, although related to body mass index in childhood, was not related to later coronary heart disease.

CONCLUSION

The highest death rates from coronary heart disease occurred in boys who were thin at birth but whose weight caught up so that they had an average or above average body mass from the age of 7 years. Death from coronary heart disease may be a consequence of poor prenatal nutrition followed by improved postnatal nutrition.

Intrauterine nutrition: its importance during critical periods for cardiovascular and endocrine development

Experimental investigations in animals have highlighted the role of early reduced calorie and protein nutrition on fetal cardiovascular development, and the occurrence of a transition from a low fetal arterial blood pressure in late gestation to a high arterial blood pressure postnatally. These observations may explain the correlation between health, including appropriate nutrition, in pregnant women and the outcome of their pregnancies. Emphasis has been placed on low birth weight infants who have an increased risk of developing cardiovascular diseases, including hypertension, coronary heart disease and stroke in adulthood. Vascular pathology in adults is not always associated with low birth weight and animal experiments indicate that substantial changes in cardiovascular and endocrine function can result from maternal or fetal undernutrition without impairing fetal growth. Experimental investigation on organogenesis shows the pivotal role of adequate protein availability as well as total caloric intake. Amino acid metabolism in the feto-maternal unit appears to have a key influence on the development of organs involved in chronic degenerative disease in the adult. Experimental investigation has also highlighted the role of carbohydrate metabolism and its effect on the fetus in this respect. Either restriction of protein intake or diabetes in pregnant rats has intergenerational effects at least on the endocrine pancreas and the brain. Further investigation is needed to clarify the mechanisms involved and lead to a new understanding of the importance of nutrition during pregnancy. This will provide an important approach to the primary prevention of diabetes and chronic degenerative diseases.

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.

Fetal origins of cardiovascular disease

Low birthweight, thinness and short body length at birth are now known to be associated with increased rates of cardiovascular disease and non-insulin dependent diabetes in adult life. The fetal origins hypothesis proposes that these diseases originate through adaptations which the fetus makes when it is undernourished. These adaptations may be cardiovascular, metabolic or endocrine. They permanently change the structure and function of the body. Prevention of the diseases may depend on prevention of imbalances in fetal growth or imbalances between prenatal and postnatal growth, or imbalances in nutrient supply to the fetus.

Ketosis resistance in the male offspring of protein-malnourished rat dams

Plasma beta-hydroxybutyrate concentrations were measured in the offspring of rats that were fed either a control (20% protein) diet or low-protein (8% protein) diet during pregnancy and lactation. Low-protein offspring had significantly lower plasma beta-hydroxybutyrate compared with controls in the fed state (P < .04) and after fasting for 24 hours (P < .001) and 48 hours (P < .04). There were no differences in blood glucose, acetoacetate, plasma glucagon, cholesterol, or glycerol between control and low-protein offspring. However, plasma nonesterified fatty acids (NEFAs) were significantly higher in low-protein offspring in the fed state (P < .05). In contrast, plasma triglycerides and insulin were significantly lower in low-protein offspring compared with controls when fed (P < .001) and after a 24-hour fast (P < .001). These results suggest that poor maternal and early postnatal nutrition can have long-term effects on ketone body metabolism in the offspring during adulthood. This apparent ketosis resistance is similar to that observed in some forms of human diabetes.

Protein deficiency and nutritional recovery modulate insulin secretion and the early steps of insulin action in rats

Maternal malnutrition was shown to affect early growth and leads to permanent alterations in insulin secretion and sensitivity of offspring. In addition, epidemiological studies showed an association between low birth weight and glucose intolerance in adult life. To understand these interactions better, we investigated the insulin secretion by isolated islets and the early events related to insulin action in the hind-limb muscle of adult rats fed a diet of 17% protein (control) or 6% protein [low (LP) protein] during fetal life, suckling and after weaning, and in rats receiving 6% protein during fetal life and suckling followed by a 17% protein diet after weaning (recovered). The basal and maximal insulin secretion by islets from rats fed LP diet and the basal release by islets from recovered rats were significantly lower than that of control rats. The dose-response curves to glucose of islets from LP and recovered groups were shifted to the right compared to control islets, with the half-maximal response (EC50) occurring at 16.9 +/- 1.3, 12.4 +/- 0.5 and 8.4 +/- 0.1 mmol/L, respectively. The levels of insulin receptor, as well as insulin receptor substrate-1 and phosphorylation and the association between insulin receptor substrate-1 and phosphatidylinositol 3-kinase were greater in rats fed a LP diet than in control rats. In recovered rats, these variables were not significantly different from those of the other two groups. These results suggest that glucose homeostasis is maintained in LP and recovered rats by an increased sensitivity to insulin as a result of alterations in the early steps of the insulin signal transduction pathway.

Impaired glucose-stimulated insulin release in islets from adult rats malnourished during foetal-neonatal life

Poor foetal and neonatal nutrition may impair normal pancreatic beta-cell development and predispose to diabetes in later life. We investigate here the nature of the pancreatic beta-cell dysfunction in sucrose-fed adult offspring malnourished during the foetal-neonatal period and examine glucose metabolism and the generation of signals involved in the secretory mechanism. In islets from sucrose-fed previously malnourished rats, rates of glucose utilisation (production of 3H2O) and oxidation (production of 14CO2), at 2, 6 and 10 mM glucose, were not lower than those of controls. ATP concentrations in islets from previously malnourished rats fed sucrose at 2 and 10 mM glucose were similar to those of controls. Glucose-stimulated insulin release was impaired (by 49-55%) in islets from these animals as was the response to keto-isocaproate (by 70%) and tolbutamide (by 70%). Under conditions in which ATP-sensitive K+ channels were clamped open (40 mM K+ and diazoxide), glucose-stimulated insulin release in islets from previously malnourished rats fed sucrose was reduced. These findings show that defects in insulin secretion in islets isolated from previously malnourished animals are located in both ATP-sensitive K+ channel dependent and independent pathways. They do not involve alterations in the early steps of glucose handling in the beta-cell, including glucose metabolism and ATP generation.

Programming by early nutrition: an experimental approach

That events during critical or sensitive periods of development may "program" long-term or life-time structure or function of the organism is well recognized. Evidence for programming by nutrition is established in animals, in whom brief pre- or postnatal nutritional manipulations may program adult size, metabolism, blood lipids, diabetes, blood pressure, obesity, atherosclerosis, learning, behavior and life span. Human epidemiological data link potential markers of early nutrition (size at birth or in infancy) to cardiovascular disease and its risk factors in adulthood. However, these retrospective data cannot prove nutritional cause or underpin health policies. After 16 y, however, of ethical, randomized intervention studies of early nutrition in humans with long-term follow-up to test experimentally the nutritional programming hypothesis, we find that humans, like other species, have sensitive windows for nutrition in terms of later outcomes; for instance, perinatal diet influences neurodevelopment and bone mineralization into mid-childhood. Possible biological mechanisms for storing throughout life the "memory" of early nutritional experience and its expression in adulthood include adaptive changes in gene expression, preferential clonal selection of adapted cells in programmed tissues and programmed differential proliferation of tissue cell types. Animal and human evidence supporting nutritional programming has major potential biological and medical significance.

Metabolic consequences of intrauterine growth retardation

Epidemiological studies have revealed strong and reproducible links between indices of poor fetal, and possibly infant, growth and susceptibility to the development of glucose intolerance and insulin resistance syndrome in adult life. The 'thrifty phenotype' hypothesis has been proposed to explain these associations. Key features of the hypothesis are: (i) intrauterine growth retardation has a nutritional basis and the resulting altered fetal environment permanently alters the development and metabolic functions of organs: (ii) these alterations are beneficial to survival in a poor nutritional environment, but may lead to diseases such as non-insulin-dependent diabetes mellitus if nutrition is abundant and obesity occurs in adult life. Tests of this hypothesis in an animal model in which pregnant and/or lactating rats were fed a diet with a reduced protein content have shown that liver metabolism in the offspring is permanently altered despite their being weaned onto a normal diet. The longevity of male offspring may be significantly increased or decreased depending on whether growth retardation is restricted to the period of suckling or pregnancy, respectively. The latter finding raises questions about potentially detrimental effects of 'catch-up' growth.

Regulation of hepatic enzymes and insulin levels in offspring of rat dams fed a reduced-protein diet

We have hypothesized that permanent changes caused by poor growth during early development due to maternal malnutrition may be exacerbated by overnutrition of offspring in later life. To test this hypothesis, rats were exposed to a maternal 20% protein diet or an isocaloric 8% protein diet during fetal and postnatal life. All offspring were weaned onto laboratory chow. At 6 wk, rats were fed laboratory chow or a highly palatable diet (high fat and high calorie with adequate protein) and studied at 12 wk after a 48-h fast. The highly palatable diet resulted in excess weight gain and higher plasma insulin levels in all animals. Plasma insulin concentrations were significantly increased in male offspring of dams fed a reduced-protein diet compared with male offspring of dams fed an adequate-protein diet, but no differences were observed between the female offspring. The key hepatic enzymes of glucose homeostasis programmed in offspring of protein-restricted rat dams retained the ability to respond to overnutrition during adult life. In these offspring, however, the enzymes were regulated around a "set point" that was different from that in the controls.

Gluconeogenesis, glucose handling, and structural changes in livers of the adult offspring of rats partially deprived of protein during pregnancy and lactation

Maternal protein restriction is a model of fetal programming of adult glucose intolerance. Perfused livers of 48-h- starved adult offspring of rat dams fed 8% protein diets during pregnancy and lactation produced more glucose from 6 mM lactate than did control livers from rats whose dams were fed 20% protein. In control livers, a mean of 24% of the glucose formed from lactate in the periportal region of the lobule was taken up by the most distal perivenous cells; this distal perivenous uptake was greatly diminished in maternal low protein (MLP) livers, accounting for a major fraction of the increased glucose output of MLP livers. In control livers, the distal perivenous cells contained 40% of the total glucokinase of the liver; this perivenous concentration of glucokinase was greatly reduced in MLP livers. Intralobular distribution of phosphenolpyruvate carboxykinase was unaltered, though overall increased activity could have contributed to the elevated glucose output. Hepatic lobular volume in MLP livers was twice that in control livers, indicating that MLP livers had half the normal number of lobules. Fetal programming of adult glucose metabolism may operate partly through structural alterations and changes in glucokinase expression in the immediate perivenous region.

Fetal and infant growth and impaired glucose tolerance in adulthood: the "thrifty phenotype" hypothesis revisited

The epidemiological links observed between fetal and infant growth and impaired glucose tolerance in adult life that led to the formulation of the "thrifty phenotype" hypothesis have been confirmed by others in widely differing populations. The proposed nutritional basis of these links has been tested in an animal model in which rat dams were fed an isocaloric low-protein diet and the postweaning normally fed offspring were studied. Permanent changes in key hepatic enzymes of glycolysis and gluconeogenesis and reductions in both insulin and glucagon sensitivity of the liver have been observed. Glucose tolerance deteriorated more at age 15 months compared with controls but animals were not frankly diabetic. The longevity of offspring was affected positively when growth was retarded by postnatal protein restriction, but negatively when protein restriction during pregnancy was followed by cross-fostering of pups to normally fed dams with consequent "catch-up" growth. These effects were greatest in males. The thrifty phenotype hypothesis continues to provide a useful conceptual and experimental basis for the study of the aetiology of non-insulin-dependent diabetes.

Altered adipocyte properties in the offspring of protein malnourished rats

It is becoming well established that poor fetal and early postnatal growth can have long-term effects on adult health, including susceptibility to non-insulin-dependent diabetes mellitus, cardiovascular disease and hypertension. It is suggested that this results from poor nutrition during early life having permanent effects on the structure and metabolism of certain organs and tissues. In the present study we investigated the effect of a low-protein diet during pregnancy and lactation on adipocyte properties and glucose tolerance. Rat dams were fed on a diet containing either 200 (control) or 80 (low protein) g protein/kg during pregnancy and lactation. In addition cross-fostering techniques were employed to enable a separate evaluation of the prenatal and postnatal periods. All offspring were weaned onto a 200 g protein/kg diet at 21 d of age and then studied at 6 weeks of age. The mothers' protein supply during lactation appeared to be the most critical time window for long-term growth. In contrast, the offspring of mothers fed on a low-protein diet during pregnancy or lactation were significantly more glucose tolerant than controls, suggesting that both time windows can have long-term effects on glucose tolerance. In addition offspring of mothers fed on a low-protein diet during pregnancy or lactation had significantly smaller adipocytes than controls. However the largest reduction in adipocyte size was observed when there was a low-protein diet during both pregnancy and lactation. The amount of insulin receptor present in adipocyte membranes was increased in the three animal groups that had been exposed to the low-protein diets while levels of the insulin responsive glucose transporter (GLUT 4) were similar in adipocyte membranes from all groups.

The effects of genotype and infant weight on adult plasma levels of fibrinogen, factor VII, and LDL cholesterol are additive

High circulating levels of cholesterol, particularly low density lipoprotein (LDL) cholesterol and the clotting factors fibrinogen and factor VII, are associated with increased risk of myocardial infarction. Variations in the plasma levels of these factors are determined in part by polymorphisms in the genes concerned and also by weight at 1 year (infant weight). We have looked at the possibility of interactions between these genetic factors and infant weight in a sample of 290 men and 192 women from Hertfordshire using the beta-fibrinogen G/A-455, factor VII R353Q, and ApoE polymorphisms. The rare allele frequencies of the three polymorphisms were 0.19 for beta-fibrinogen, 0.10 for factor VII, and 0.07 and 0.13 for the 2 and 4 alleles of ApoE, and these frequencies were not different in subjects of different infant weight. In this sample, the polymorphisms showed the expected effects on plasma levels of fibrinogen, factor VII, and LDL cholesterol. The A-455 allele was associated with higher fibrinogen levels but the effect was only statistically significant in women (p = 0.003). The R353 allele was associated with higher factor VII activity in both men and women (p < 0.0001 for both). The ApoE2 allele was associated with lower levels of LDL cholesterol (p = 0.03 in men, p = 0.006 in women), while the ApoE4 allele was associated with higher levels (p < 0.001 in men, not significant in women). In this sample of men and women the effect of low infant weight was only associated with significant effects on fibrinogen and LDL cholesterol in the group of men (p = 0.005 and p = 0.008 respectively). Compared with the E3E3 subjects, the LDL lowering effect of the E2 allele and the raising effect of the E4 allele was greater in those with low infant weight compared with those with high infant weight (low v high infant weight for E2: 12.7% v 9.4%; for E4 12.7% v 8.5%). Although in this sample the interactive effect did not reach statistical significance, the additive effect of ApoE genotype and low infant weight on determining plasma LDL cholesterol levels, if confirmed, may be of relevance in determining a person's future risk of atherosclerosis.