Molecular cloning and expression of a new gene,GON-SJTU1 in the rat testis

Background

A prolonged latent phase is independently associated with an increased incidence of subsequent labor abnormalities. We aimed to compare between oxytocin augmentation, amniotomy and a combination of both on the duration of labor among women with a prolonged latent phase.

Methods

Women with a singleton fetus in cephalic presentation who have a prolonged latent phase, were randomly allocated to amniotomy (group 1), oxytocin (group 2) or both (group 3). A group of women who progressed spontaneously without intervention composed the control group (group 4). The primary outcome was the duration of time from initiation of augmentation until delivery.

Results

A total of 213 women were consented and randomized to group 1 (70 women), group 2 (72 women) and group 3 (71 women). Group 4 was composed from additional 70 women. A mean reduction of 120 minutes in labor duration was observed among group 3 compared to group 1 (p = 0.08) and 180 minutes compared to group 2 and 4 (p = 0.001). Women in group 3 had a shorter length of time from augmentation until the beginning of the active phase and a shorter first stage of labor than group 1 (p = 0.03), group 2 (p = 0.001) and group 4 (p = 0.001). Satisfaction was greater among group 3 and 4. Mode of delivery and neonatal outcome were comparable between the groups.

Conclusion

Labor augmentation by combined amniotomy and oxytocin among women with a prolonged latent phase at term seems superior compared to either of them alone.     

Metabolic syndrome in polycystic ovary syndrome

Both metabolic syndrome (MS) and polycystic ovary syndrome (PCOS) are common among women. The exact prevalence of MS in women with PCOS is dependent upon the diagnostic criteria used for each. However, the frequent co-occurrence of both MS and PCOS in women is suggestive of a common aetiology. In this short review article we argue that insulin resistance, as a consequence of abdominal obesity, may represent such a common aetiology. We also review the literature on the prevalence of MS in women with PCOS and consider the impact that the particular criteria used to diagnose both MS and PCOS may have had on these estimates of prevalence.     

Effects of pregnancy and labor on oxytocin levels in human plasma and cerebrospinal fluid

In order to investigate the significance of oxytocin in pregnancy and labor, oxytocin concentrations in plasma and cerebrospinal fluid (CSF) were determined using the specific radioimmunoassay. Plasma and CSF samples were obtained from 23 pregnant women (11 pre labor, 12 in labor), 15 nonpregnant women and 4 men at spinal puncture for anesthesia. In males and nongravidas, CSF levels of oxytocin were significantly higher than plasma levels. Plasma levels in pregnant patients pre or in labor were significantly higher than those in nongravidas. No significant difference between CSF levels in prelabor gravidas (mean +/- SE, 9.7 +/- 1.5 mu u/ml) and nongravidas (10.1 +/- 1.2 mu u/ml) was found. However, CSF levels in gravidas in labor (18.6 +/- 2.3 micromicrons/ml were significantly higher than the levels in prelabor gravidas. These results strongly suggest that oxytocin levels in human plasma and CSF are controlled by different mechanisms and that the increased oxytocin could have some specific central actions.     

Effects of inactivation of oxytocin receptor and inhibition of prostaglandin synthesis on uterine oxytocin receptor and gap junction formation and labor in the rat.

Normal term labor is associated with a surge in myometrial oxytocin receptor formation and gap junction development. We have previously shown that inhibition of prostaglandin synthesis by naproxen sodium, 2.0 mg/day, suppressed oxytocin receptor formation but not gap junction formation and prolonged gestation. In this study, we investigated the effects of a specific oxytocin antagonist on oxytocin receptor formation, gap junction formation, and labor in the rat. [Pen1,Phe(Me)2,Thr4,Orn8]oxytocin, a specific oxytocin antagonist, was infused subcutaneously during the last 3 days of pregnancy at 300 micrograms/day. Measurements of myometrial oxytocin receptor concentrations and gap junction formation on days 21 and 22 and days 22-23 (in labor) pregnant uteri showed no significant differences in the Bmax and Kd values between the control and the treated group. Gestation period was not prolonged by the oxytocin antagonist. However, in a separate group of day 23 pregnant rats, the uterine contractile response to 60 mU of oxytocin i.v. was found completely blocked by 10 micrograms of the oxytocin antagonist. These findings suggest that although functional oxytocin receptors did not appear to be essential for the initiation of labor, oxytocin antagonists may still be effective in the prevention of premature contractions. We also examined the effects of a higher dose of naproxen sodium, 5.0 mg/day, on gap junction formation. At this dose, naproxen sodium suppressed both oxytocin receptor and gap junction formation, prolonged gestation, and delayed parturition by 24 h or longer. Prostaglandin appears to be an important regulator or mediator of oxytocin receptor and gap junction formation and plays a critical role in the initiation of labor.     

Surgical management of metabolic dysfunction in PCOS

Metabolic disturbances are common in women with polycystic ovary syndrome (PCOS). Obesity is the major link in the association of PCOS with diabetes, metabolic syndrome, hypertension, low-grade chronic inflammation and increased body iron stores, among others. Metabolic prevention in PCOS women should start as early as possible, usually meaning at diagnosis. Among preventive strategies, those promoting a healthy life-style based on diet, regular exercising and smoking cessation are possibly the most effective therapies, but also are the most difficult to achieve. To this regard, every effort must be made to avoid weight gain and obesity, given the deleterious impact that obesity exerts on the metabolic and cardiovascular associations of PCOS. Unfortunately, classic strategies that address obesity by life-style modification and dieting are seldom successful on a long-term basis, especially in women with severe obesity. In selected cases, metabolic surgery in severely obese women may resolve signs and symptoms of PCOS restoring insulin sensitivity and fertility, and avoiding the long-term risks associated with PCOS and morbid obesity. Surgical techniques for bariatric surgery have evolved in the past decades and newer procedures do not longer carry the severe side effects associated with earlier bariatric procedures. The choice of bariatric procedure should consider both the severity of obesity and the possibility of future pregnancy, since fertility may be restored by the sustained and marked weight loss usually attained after bariatric surgery. Finally, avoidance of the risks associated with morbid obesity compensate for the possible residual risks for pregnancy derived from the previous bariatric procedure itself.     

The relationship of body fat to metabolic disease: Influence of sex and ethnicity

Clinical investigations designed to determine risk profiles for the development of cardiovascular disease (CVD) and type 2 diabetes mellitus (DM) are usually performed in homogenous populations and often focus on body mass index (BMI), waist circumference (WC), and fasting triglyceride (TG) levels. However, there are major ethnic differences in the relationship of these risk factors to outcomes. For example, the BMI risk threshold may be higher in blacks than in whites and higher in women than in men. Furthermore, a WC that predicts an obese BMI in white women only predicts a BMI in the overweight category in black women. In addition, overweight black men have a greater risk of developing type 2 DM than do overweight black women. Although TG levels are excellent predictors of insulin resistance in whites, they are not effective markers of insulin resistance in blacks. Among the criteria sets currently available to predict the development of CVD and type 2 DM, the most well known is the metabolic syndrome. The metabolic syndrome has 5 criteria: central obesity, hypertriglyceridemia, low high-density lipoprotein (HDL) levels, fasting hyperglycemia, and hypertension. To make the diagnosis of the metabolic syndrome, 3 of the 5 factors must be present. For central obesity and low HDL, the metabolic syndrome guidelines are sex specific. Diagnostic guidelines should also take ethnic differences into account, particularly in the diagnosis of central obesity and hypertriglyceridemia.     

Fatty-acid-mediated hypothalamic inflammation and epigenetic programming

A high-fat diet is the main environmental cue that has been studied in the hypothalamus since the discovery of its connection with hypothalamic inflammation. Current evidence shows hypothalamic inflammation as a likely mechanism for the dysregulation on the homeostatic control of energy balance, which leads to metabolic alterations and obesity. Although this mechanism seems to be reversible when set during adulthood, we argue whether dietary fatty acids, during critical periods of development, could affect hypothalamic function permanently and set an increased susceptibility to obesity. We found few experimental studies that looked at programming induced by different fatty acids on the hypothalamus. They clearly showed a connection between maternal fat diet, hypothalamic inflammation and metabolic alterations in the offspring. We found that not only a high-fat diet but also a normolipidic diet with unbalanced quantities of different fatty acids produced diverse inflammatory responses on the hypothalamus. Therefore, strategies of manipulating dietary fatty acids in pregnant and lactating women may have great impact on the population's future health. However, more research is still needed on the effects of fatty acids and the hypothalamic inflammation on programming.     

Obesity and cardiovascular disease

Available evidence clearly indicates a rapid progression in the prevalence of obesity worldwide. As a consequence, there has also been a marked increase in the prevalence of type 2 diabetes all over the world and this chronic metabolic disease is now considered as a coronary heart disease risk equivalent. However, even in the absence of the hyperglycaemic state which characterizes type 2 diabetic patients, non diabetic individuals with a specific form of obesity, named abdominal obesity, often show clustering metabolic abnormalities which include high triglyceride levels, increased apolipoprotein B, small dense low density lipoproteins and decreased high density lipoproteins-cholesterol levels, a hyperinsulinemic-insulin resistant state, alterations in coagulation factors as well as an inflammatory profile. This agglomeration of abnormalities has been referred to as the metabolic syndrome which can be identified by the presence of three of the five following variables: abdominal obesity, elevated triglyceride concentrations, low HDL-cholesterol levels, increased blood pressure and elevated fasting glucose. Post-mortem analyses of coronary arteries have indicated that obesity (associated with a high accumulation of abdominal fat measured at autopsy) was predictive of earlier and greater extent of large vessels atherosclerosis as well as increase of coronary fatty streaks. Metabolic syndrome linked to abdominal obesity is also predictive of recurrent coronary events both in post-myocardial infarction patients and among coronary artery disease men who underwent a revascularization procedures. It is suggested that until the epidemic progression of obesity is stopped and obesity prevented or at least properly managed, cardiologists will be confronted to an evolving contribution of risk factors where smoking, hypercholesterolemia and hypertension may be relatively less prevalent but at the expense of a much greater contribution of abdominal obesity and related features of the metabolic syndrome.     

Increased prevalence of metabolic syndrome in patients with acne inversa

Background

Acne inversa (AI; also designated as Hidradenitis suppurativa) is a common chronic inflammatory skin disease, localized in the axillary, inguinal and perianal skin areas that causes painful, fistulating sinuses with malodorous purulence and scars. Several chronic inflammatory diseases are associated with the metabolic syndrome and its consequences including arteriosclerosis, coronary heart disease, myocardial infraction, and stroke. So far, the association of AI with systemic metabolic alterations is largely unexplored.

Methods and Findings

A hospital-based case-control study in 80 AI patients and 100 age- and sex-matched control participants was carried out. The prevalence of central obesity (odds ratio 5.88), hypertriglyceridemia (odds ratio 2.24), hypo-HDL-cholesterolemia (odds ratio 4.56), and hyperglycemia (odds ratio 4.09) in AI patients was significantly higher than in controls. Furthermore, the metabolic syndrome, previously defined as the presence of at least three of the five alterations listed above, was more common in those patients compared to controls (40.0% versus 13.0%; odds ratio 4.46, 95% confidence interval 2.02 to 9.96; P<0.001). AI patients with metabolic syndrome also had more pronounced metabolic alterations than controls with metabolic syndrome. Interestingly, there was no correlation between the severity or duration of the disease and the levels of respective parameters or the number of criteria defining the metabolic syndrome. Rather, the metabolic syndrome was observed in a disproportionately high percentage of young AI patients.

Conclusions

This study shows for the first time that AI patients have a high prevalence of the metabolic syndrome and all of its criteria. It further suggests that the inflammation present in AI patients does not have a major impact on the development of metabolic alterations. Instead, evidence is given for a role of metabolic alterations in the development of AI. We recommend monitoring of AI patients in order to correct their modifiable cardiovascular risk factors.     

P wave indices, obesity, and the metabolic syndrome: the atherosclerosis risk in communities study

Atrial fibrillation and obesity are increasing in prevalence and are interrelated epidemics. There has been limited assessment of how obesity and the metabolic syndrome impact P wave indices, established electrocardiographic predictors of atrial fibrillation. We conducted a cross-sectional analysis to determine the association of obesity and the components of the metabolic syndrome with P wave indices in the population-based Atherosclerosis Risk in Communities (ARIC) study. Analyses were adjusted for demographic, anthropometric and clinical variables, and cardiovascular diseases and risk factors. Following relevant exclusions, 14,433 subjects were included (55% women and 24.7% black). In multivariable analyses, we identified significant, progressive increases in PR interval, P wave maximum duration, and P wave terminal force with BMI 25-30 kg/m(2) and BMI ≥30 kg/m(2) compared to the reference group <25 kg/m(2) (P < 0.0001 for trend for all P wave indices). These effects were present in both blacks and whites. Presence of metabolic syndrome was also associated with longer P wave indices. When components of the metabolic syndrome were examined separately, hypertension resulted in significant (P < 0.001) augmentation of the three P wave indices. Similarly, waist circumference was associated with greater P wave maximum duration in both races (P < 0.001). We concluded that P wave indices are significantly associated with obesity and particularly with hypertension and waist circumference. P wave indices may comprise intermediate markers, independent of age and cardiovascular risk, of the pathway linking obesity and with the risk of atrial fibrillation (AF).     

Metabolic syndrome risk in black South African women compared to Caucasian women.

Rapid urbanisation has led African women to have an obesity prevalence double than that of Caucasian women, and this also holds true for the stroke prevalence in Africans. The study aimed to compare various metabolic syndrome (MS) criteria of the International Diabetes Federation (IDF) of body mass index and age-matched African (n=102) and Caucasian women (n=115). More Caucasian (30.4%) than African women (24.8%) had MS. Only 48% of African women had waist circumferences (WC) higher than the IDF cutoff, compared to 62.6% of Caucasians. Caucasian women were significantly taller and heavier and had higher triglycerides, plasminogen activator inhibitor-1 activity, and cortisol. African women had significantly higher blood pressure, leptin, fibrinogen and C-reactive protein, and higher odds ratios for having the MS for HDL-cholesterol, blood pressure, and fasting glucose than Caucasians. It is concluded that the IDF WC criterion needs a downward adjustment for African women due to a smaller body size. Lean African women seem to be at higher risk for MS than Caucasians. South Africa needs to stem the increasing rates of type 2 diabetes by decreasing obesity and by education (unschooled African women showed a 4.8 times higher likelihood of having MS than schooled women).     

Differences in daily rhythms of wrist temperature between obese and normal-weight women: associations with metabolic syndrome features

The circadian rhythm of core body temperature is associated with widespread physiological effects. However, studies with other more practical temperature measures, such as wrist (WT) and proximal temperatures, are still scarce. The aim of this study was to investigate whether obesity is associated with differences in mean WT values or in its daily rhythmicity patterns. Daily patterns of cortisol, melatonin, and different metabolic syndrome (MetS) features were also analyzed in an attempt to clarify the potential association between chronodisruption and MetS. The study was conducted on 20 normal-weight women (age: 38 ± 11 yrs and BMI: 22 ± 2.6 kg/m(2)) and 50 obese women (age: 42 ± 10 yrs and BMI: 33.5 ± 3.2 kg/m(2)) (mean ± SEM). Skin temperature was measured over a 3-day period every 10 min with the "Thermochron iButton." Rhythmic parameters were obtained using an integrated package for time-series analysis, "Circadianware." Obese women displayed significantly lower mean WT (34.1°C ± 0.3°C) with a more flattened 24-h pattern, a lower-quality rhythm, and a higher intraday variability (IV). Particularly interesting were the marked differences between obese and normal-weight women in the secondary WT peak in the postprandial period (second-harmonic power [P2]), considered as a marker of chronodisruption and of metabolic alterations. WT rhythmicity characteristics were related to MetS features, obesity-related proteins, and circadian markers, such as melatonin. In summary, obese women displayed a lower-quality WT daily rhythm with a more flattened pattern (particularly in the postprandial period) and increased IV, which suggests a greater fragmentation of the rest/activity rhythm compared to normal-weight women. These 24-h changes were associated with higher MetS risk.     

Trends in Overweight and Obesity in Portugal: The National Health Surveys 1995–6 and 1998–9

Objective: To assess overweight and obesity trends in the Portuguese population. Research Methods and Procedures: National Health Surveys, conducted in 1995–6 (17, 989 men; 20, 249 women) and 1998–9 (17, 923 men; 20, 302 women), were used. Results: In men, the prevalence of overweight and obesity increased from 39.9% (95% CI: 39.2 to 40.6) and 10.3% (95% CI: 9.9 to 10.7), respectively, in 1995–6, to 42.5% (95% CI: 41.8 to 43.2) and 11.5% (95% CI: 11.0 to 12.0), respectively, in 1998–9. In women, prevalence of obesity increased from 12.7% (95% CI: 12.2 to 13.2) in 1995–6 to 14.2% (95% CI: 13.7 to 14.6) in 1998–9, whereas the prevalence of overweight remained stable: 32.2% (95% CI: 31.6 to 32.9) in 1995–6 and 32.3% (95% CI: 31.6 to 32.9) in 1998–9. In men, prevalence of overweight and obesity were higher among former smokers and educational group of 6 to 12 years, and prevalence of obesity was higher in the Lisbon region. In women, prevalence of overweight and obesity were higher among never smokers, and prevalence of obesity was higher among educational group of ?6 years. Prevalence of obesity was higher in the Alentejo region, and overweight was higher in the Center region. Finally, prevalence of obesity increased in both sexes for all strata studied (age, smoking status, educational level, and geographic region), whereas prevalence of overweight increased only in men. Discussion: In Portugal, overweight and obesity levels are related to sociodemographic factors; the increase in obesity levels stresses the need for preventive measures.     

Genetic aspects of susceptibility to obesity and related dyslipidemias

Obesity has a multifactorial origin. However, although environmental variables undoubtedly play a role in the development of obesity, it is now clear that genetic variation is also involved in the determination of an individual's susceptibility to body fat accumulation. In addition, it is also widely accepted that obesity is not a single homogeneous phenotype. It is also heterogeneous regarding its causes and metabolic complications. The regional distribution of body fat appears to be an important correlate of the metabolic complications that have been related to obesity. Due to their higher accumulation of abdominal fat, men are generally more at risk for the metabolic complications of obesity than women whereas some obese women, with large gluteal-femoral adipose depots may have a cosmetic problem which may not necessarily require medical intervention. Several studies have been conducted to understand the mechanisms by which abdominal obesity is related to diabetes, hypertension and cardiovascular disease. It appears that the increased risk of abdominal obesity is the result of complex hormonal and metabolic interactions. Studies in genetic epidemiology have shown that both total body fatness and the regional distribution of body fat have a significant genetic component. Standardized intervention studies using an identical twin design have shown that individuals that have the same genetic background tend to show similar changes in body fat and in plasma lipoprotein levels when exposed to standardized caloric excess or energy restriction. Finally, although abdominal obesity is a significant risk factor for cardiovascular disease, not every abdominal obese subject will experience metabolic complications, suggesting that some obese individuals may be more susceptible than others. Variation in several genes relevant to lipid and lipoprotein metabolism may alter the relation of abdominal obesity to dyslipoproteinemias. Abdominal obesity should therefore be considered as a factor that exacerbates an individual's susceptibility to cardiovascular disease.     

Role of oxytocin in energy metabolism

The basic mechanisms that lead obesity are not fully understood; however, several peptides undoubtedly play a role in regulating body weight. Obesity, a highly complex metabolic disorder, involves central mechanisms that control food intake and energy expenditure. Previous studies have shown that central or peripheral oxytocin administration induces anorexia. Recently, in an apparent discrepancy, rodents that were deficient in oxytocin or the oxytocin receptor were shown to develop late-onset obesity without changing their total food intake, which indicates the physiological importance of oxytocin to body metabolism. Oxytocin is synthesized not only within magnocellular and parvocellular neurons but also in several organs, including the ovary, uterus, placenta, testis, thymus, kidney, heart, blood vessels, and skin. The presence of oxytocin receptors in neurons, the myometrium and myoepithelial cells is well recognized; however, this receptor has also been identified in other tissues, including the pancreas and adipose tissue. The oxytocin receptor is a typical class I G protein-coupled receptor that is primarily linked to phospholipase C-β via Gq proteins but can also be coupled to other G proteins, leading to different functional effects. In this review, we summarize the present knowledge of the effects of oxytocin on controlling energy metabolism, focusing primarily on the role of oxytocin on appetite regulation, thermoregulation, and metabolic homeostasis.     

Metabolic imprinting: critical impact of the perinatal environment on the regulation of energy homeostasis

Epidemiological studies in humans suggest that maternal undernutrition, obesity and diabetes during gestation and lactation can all produce obesity in offspring. Animal models have allowed us to investigate the independent consequences of altering the pre- versus post-natal environments on a variety of metabolic, physiological and neuroendocrine functions as they effect the development in the offspring of obesity, diabetes, hypertension and hyperlipidemia (the 'metabolic syndrome'). During gestation, maternal malnutrition, obesity, type 1 and type 2 diabetes and psychological, immunological and pharmacological stressors can all promote offspring obesity. Normal post-natal nutrition can reduce the adverse impact of some of these pre-natal factors but maternal high-fat diets, diabetes and increased neonatal access to food all enhance the development of obesity and the metabolic syndrome in offspring. The outcome of these perturbations of the perinatal environmental is also highly dependent upon the genetic background of the individual. Those with an obesity-prone genotype are more likely to be affected by factors such as maternal obesity and high-fat diets than are obesity-resistant individuals. Many perinatal manipulations appear to promote offspring obesity by permanently altering the development of central neural pathways, which regulate food intake, energy expenditure and storage. Given their strong neurotrophic properties, either excess or an absence of insulin and leptin during the perinatal period are likely to be effectors of these developmental changes. Because obesity is associated with an increased morbidity and mortality and because of its resistance to treatment, prevention is likely to be the best strategy for stemming the tide of the obesity epidemic. Such prevention should begin in the perinatal period with the identification and avoidance of factors which produce permanent, adverse alterations in neural pathways which control energy homeostasis.     

Oxytocin increases VTA activation to infant and sexual stimuli in nulliparous and postpartum women

After giving birth, women typically experience decreased sexual desire and increased responsiveness to infant stimuli. These postpartum changes may be viewed as a trade-off in reproductive interests, which could be due to alterations in brain activity including areas associated with reward. The goal of this study was to describe the roles of oxytocin and parity on reward area activation in response to reproductive stimuli, specifically infant and sexual images. Because they have been shown to be associated with reward, the ventral tegmental area (VTA) and nucleus accumbens (NAc) were targeted as areas of expected alterations in activity. Oxytocin was chosen as a potential mediator of reproductive trade-offs because of its relationship to both mother–infant interactions, including breastfeeding and bonding, and sexual responses. We predicted that postpartum women would show higher reward area activation to infant stimuli and nulliparous women would show higher activation to sexual stimuli and that oxytocin would increase activation to infant stimuli in nulliparous women. To test this, we measured VTA and NAc activation using fMRI in response to infant photos, sexual photos, and neutral photos in 29 postpartum and 30 nulliparous women. Participants completed the Sexual Inhibition (SIS) and Sexual Excitation (SES) Scales and the Brief Index of Sexual Function for Women (BISF-W), which includes a sexual desire dimension, and received either oxytocin or placebo nasal spray before viewing crying and smiling infant and sexual images in an fMRI scanner. For both groups of women, intranasal oxytocin administration increased VTA activation to both crying infant and sexual images but not to smiling infant images. We found that postpartum women showed lower SES, higher SIS, and lower sexual desire compared to nulliparous women. Across parity groups, SES scores were correlated with VTA activation and subjective arousal ratings to sexual images. In postpartum women, sexual desire was positively correlated with VTA activation to sexual images and with SES. Our findings show that postpartum decreases in sexual desire may in part be mediated by VTA activation, and oxytocin increased activation of the VTA but not NAc in response to sexual and infant stimuli. Oxytocin may contribute to the altered reproductive priorities in postpartum women by increasing VTA activation to salient infant stimuli.     

Differential Impact of Obesity in Related Populations

To search for genetic and environmental determinants of obesity, we compared the prevalences and the impact of obesity in three populations from two cities: Mexican Amcricans (n=820) and non-Hispanic whites (n=1112)from San Antonio, Texas, and Mexicans from Mexico City (n= 1878). In the age range examined, 35–64 years, only Mexican men and women showed a significant increase in the prevalence of obesity with age. On the other hand, genetic ancestry, especially in women, made significant differences in the rates of obesity. Mexican Americans showed relatively high, and non-Hispanic whites low, rates of obesity. To discriminate between genetic and environmental influences mediating the impact of obesity on a set of hemodynamic and metabolic variables, we compared this impact between Mexican Americans and both non-Hispanic whites (same macro-environment, different gene pools), and Mexicans (same gene pool, different environments). We found that obesity always worsens the hemodynamic and metabolic profiles of individuals, but the magnitude of the effects may be variable. We showed that the levels of insulin concentrations for a given level of obesity were similar in Mexicans and Mexican Americans, suggesting that genetic influences predominate in determining insulin levels; the levels of triglycerides and HDL for a given level of obesity were similar in Mexican Americans and non-Hispanic whites, suggesting predominant environmental influences on lipid levels. On the other hand, the levels of glucose and systolic blood pressure for a given level of obesity were usually different between Mexican Americans and either of the other two populations, suggesting that these levels may result from genotype-by-environment interactions.