Trends in maternal obesity incidence rates, demographic predictors, and health inequalities in 36,821 women over a 15-year period

OBJECTIVE: The aim of this study was to identify trends in maternal obesity incidence over time and to identify those women most at risk and potential-associated health inequalities. DESIGN: Longitudinal database study. SETTING: James Cook University Hospital maternity unit, Middlesbrough, UK. SAMPLE: A total of 36 821 women from 1 January 1990 to 31 December 2004. METHODS: Trends in maternal obesity incidence over time were analysed using chi-square test for trend. Demographic predictor variables were analysed using multivariate logistic regression, adjusting for confounding factors after testing for multicollinearity. National census data were used to place the regional data into the context of the general population. MAIN OUTCOME MEASURE: Trends in maternal obesity incidence. Demographic predictor variables included ethnic group, age, parity, marital status, employment and socio-economic disadvantage. RESULTS: The proportion of obese women at the start of pregnancy has increased significantly over time from 9.9 to 16.0% (P<0.01). This is best described by a quadratic model (P<0.01) showing that the rate is accelerating; by 2010, the rate will have increased to 22% of this population if the trend continues. There is also a significant relationship with maternal obesity and mothers' residing in areas of most deprivation (odds ratio [OR]=2.44, 95% CI=1.98, 3.02, P<0.01), with increasing age (OR=1.04, 95% CI=1.04, 1.05, P<0.01), and parity (OR=1.17, 95% CI=1.12, 1.21, P<0.01). CONCLUSIONS: The incidence of maternal obesity at the start of pregnancy is increasing and accelerating. Predictors of maternal obesity are associated with health inequalities, particularly socio-economic disadvantage.     

Nucleotide diversity in the Hsp90 gene in natural populations of Drosophila melanogaster from Australia

Hsp90 is regarded as one of the best candidates for an evolved mechanism that regulates the expression of genetic and phenotypic variability. We examined nucleotide diversity in both the promoter and coding regions of Hsp90, the gene which encodes Hsp90 in Drosophila, in natural populations of Drosophila melanogaster from eastern Australia. We found that Hsp90 is polymorphic for only two nonsynonymous changes in the coding region, both of which are deletions of a lysine residue. One of these lysine deletions was in complete linkage disequilibrium with the inversion In(3L)P, and showed a significant association with latitude. The other lysine deletion reported here for the first time varied from 0 to 15% in natural populations, but did not show a clinal pattern. The regulatory and coding regions of Hsp90 showed very low nucleotide diversity compared to other nuclear genes, and chromosomes containing In(3L)P had lower levels of nucleotide diversity than the standard arrangements. Non‐neutral evolution of Hsp90 was not supported by analyses of either the regulatory or coding regions of the gene. These results are discussed within the context of Hsp90 variation being involved in thermotolerance as well as the expression of genetic and phenotypic variability.     

Dietary intake, serum lipids, insulin resistance and body composition in the era of highly active antiretroviral therapy 'Diet FRS Study'

OBJECTIVES: To investigate (i) differences in dietary fat and energy intake between those reporting and those not reporting fat redistribution syndrome (FRS), and (ii) the relationship between dietary fat, total energy intake, serum biochemistry and the clinical characteristics of the syndrome. DESIGN: A cross-sectional study. SETTING: Outpatient service of a tertiary referral hospital, Sydney, Australia. PATIENTS AND METHODS: Dietary intake, serum lipids and insulin resistance and body composition (fat-free mass, fat mass, waist-to-hip ratio; WHR) were determined in 100 HIV-positive patients whose FRS status was classified on the basis of self-report of body composition changes, verified by clinical examination. RESULTS: There was no significant difference in total or saturated dietary fat intake when grouped by FRS status. There was no significant correlation between dietary saturated or total fat intake and the serum or body composition parameters measured. Total energy intake was higher in those patients reporting FRS (14575 versus 12283 kJ, P = 0.037) after adjustment for age, smoking and exercise status. CONCLUSION: There appears to be no relationship between either dietary saturated or total fat intake and the serum or body composition parameters characteristic of FRS; however, the total energy intake was significantly higher in those with FRS. The nature of the relationship between total energy intake and FRS (cause or effect) warrants further investigation.     

Validity of the allometric cascade model at submaximal and maximal metabolic rates in exercising men

The dependence of metabolic rate (MR) on body mass (M) is described by the general allometric equation MR=aM(b), where, a is a proportionality coefficient and b is the mass exponent. Darveau et al. [Nature 417 (2002), 166] proposed a novel 'multiple-causes' allometric cascade model as a unifying principle of the scaling of MR, at rest and during maximal exercise. We tested the validity of body mass exponents predicted from the model for submaximal and maximal aerobic exercise conditions in 1629 men. MRs were estimated from whole-body oxygen consumption during an incremental treadmill test to voluntary exhaustion. For both submaximal (b=0.83) and maximal (b=0.94) exercise requiring average oxygen consumption rates of around 5-11 times resting values, respectively, the obtained mass exponents were remarkably consistent with predicted values. Moreover, for maximal MR the global mass exponent was significantly greater than for submaximal aerobic metabolism, congruent with the allometric cascade model.     

Caring for the underserved: blending service learning and a web-based curriculum

BACKGROUND: Recognition of health disparities among underserved individuals, whose demographic, geographic, or economic characteristics impede access to health-related services, has led to calls for the development of medical school curricula that address care for the underserved, but reports of the development and evaluation of such curricula are limited. METHODS: Two formats of a curriculum addressing care for the underserved were developed and implemented during the 6-week pediatric clerkship for third-year medical students during the 2003-2004 academic year. One format was faculty-led; the other was web-based. Skills for providing care to underserved families were taught through didactic, experiential, and service-learning curriculum components. Novel core curriculum elements included a screening tool for recognizing underserved patients and an independent clinical project through which students linked underserved families with community health resources. Analyses from 2004-2005 compared pre- and post-curriculum knowledge and attitudes of web-based students (n = 29) to those receiving either the faculty-led (n = 36) or the established "readings-only" curriculum (n = 35). Qualitative data from service learning projects were analyzed to assess clinical skills. RESULTS: Compared to students in the established curriculum, both web-based and faculty-led students demonstrated improved knowledge (p < 0.001) and attitudes (p < 0.05) about caring for the underserved. Both web-based and faculty-led students were successful in recognizing and addressing underserved health issues in the clinical setting. CONCLUSIONS: Faculty-led and web-based curricula can equally improve student knowledge, attitudes, and skills about caring for the underserved.     

Assessment of low-to-moderate intensity physical activity thermogenesis in young adults using synchronized heart rate and accelerometry with branched-equation modeling

Low-to-moderate intensity physical activity thermogenesis is a highly variable and quantitatively important component of total energy expenditure that is difficult to assess outside the laboratory. Greater precision and accuracy in the measurement of this key contributor to energy balance is a research priority. We developed a laboratory-based protocol that simulated a range of low-to-moderate intensity physical activities. We characterized the bias and random (individual) error in estimating energy expenditure using combined accelerometry and heart rate (AHR) with branched-equation modeling and a simple motion sensor (pedometer) against an indirect calorimetry criterion. Twenty young adult subjects performed a 2-h laboratory-based protocol, simulating 6 low-to-moderate intensity physical activities interspersed with periods of rest. The physical activity level during the laboratory-based protocol reflected an energy expenditure toward the lower end of the active category. We found that AHR-derived energy expenditure showed no evidence of substantial fixed or proportional bias (mean bias 6%), whereas pedometer-derived energy expenditure showed both fixed and proportional bias (bias at minimum, mean, and maximum energy expenditure +11, -20, and -36%, respectively). It appears that AHR provides an accurate estimate of criterion energy expenditure whereas a simple motion sensor (pedometer) does not. It is noteworthy that AHR provides quantitative information about the nature and patterns of physical activity, such as the amount of time and/or energy spent engaged in physical activity above critical health-related thresholds.     

Allometric analysis of the association between cardiac dimensions and body size variables in 464 junior athletes

Empirically derived relationships between body size variables and cardiac dimensions have not been published previously for a large sample of male and female athletes. This process would inform scaling practice and facilitate intra- and inter-group comparisons of cardiac data. Therefore we investigated the relationships of body mass (BM), height and body surface area (BS) with a range of cardiac dimensions derived by echocardiography in 464 male and female elite junior athletes (age range 14-18 years; sporting allocation included rowers, cyclists, footballers, tennis players, swimmers and a miscellaneous group). Initial linearity checks suggested that most of the relationships between the body size variables and cardiac dimensions were non-linear, thus precluding the simple ratio standard approach to scaling. Multiple log-log least-squares linear regression confirmed commonality of slopes (between males and females, across the age range and between sporting groups) for all relationships involving BM and BS. Subsequent analyses of the slope exponent (b) for left ventricular dimensions supported previous data and were dimensionally consistent (LVM-BM, b=0.91+/-0.11; LVM-BS, b=1.44+/-0.19; where LVM is left ventricular mass), except for left ventricular internal dimension in diastole (LVIDd) (LVIDd-BM, b=0.25+/-0.04). Data for the left atria internal dimension (LA) were also dimensionally consistent (LA-BM, b=0.29+/-0.09); however, this was not the case for the right ventricular internal dimension in diastole (RVIDd) (RVIDd-BM, b=0.76+/-0.14). It is possible that these results were due to a study-specific limitation in the data range (LVIDd) and the geometric peculiarities of RVIDd compared with LVIDd. The gender/age/sporting groupxbody size interaction factor for virtually all relationships between height and cardiac dimensions was significant (P<0.05), and thus whole-group b exponents could not be generated. Generally these data support previous small-sample research with athletes, and suggest that allometric scaling, as opposed to simple ratio scaling, should be adopted in studies of cardiac dimensions in athletes. This should allow, with minimal mathematical difficulty, the production of body-size-independent cardiac indices to be evaluated in laboratory or clinical work. Further research is required to develop normative 'allometrically derived' cardiac indices, and care should be taken to determine relationships in specific population groups as well as to confirm commonality of slopes in multiple group comparisons. Caution is expressed regarding the use of height as a scaling variable in future research.     

A comparison of megestrol acetate, nandrolone decanoate and dietary counselling for HIV associated weight loss

This randomized, prospective study compared three treatments, nandrolone decanoate (ND), megestrol acetate (MA) or dietary counselling, for managing human immunodeficiency syndrome (HIV) associated weight loss. It was centred on a Tertiary referral hospital, Sydney, Australia. Fifteen patients were randomized to receive ND (100 mg/fortnight), or MA (400 mg/day) or dietary counselling for 12 weeks. Those patients randomized to dietary counselling were further randomized to receive nandrolone or megestrol after completing the dietary counselling arm. Weight, fat free mass (FFM), percentage body fat mass (FM), dietary intake and appetite were assessed before commencing and at the completion of each treatment arm. Weight increased significantly in all treatment arms (dietary counselling 1.13 kg +/- 0.36, nandrolone 4.01 kg +/- 1.68, megestrol 10.20 kg +/- 4.51, p < 0.05 paired t-test). FFM increased significantly in patients receiving ND (3.54 +/- 1.98 kg, p=0.001) and those receiving MA (2.76 +/- 0.55 kg, p=0.002), whereas the change in those receiving dietary counselling alone was not significant. Percentage body fat mass increased significantly only in those receiving MA (7.77 +/- 4.85%, p=0.049). The change in weight and percentage body fat mass was significantly greater in those receiving MA than the other two treatment arms. The increase in FFM was significantly greater in both the nandrolone and megestrol arms than the dietary counselling arm. It was concluded that ND and MA both resulted in an increase in FFM greater than dietary counselling alone. Megestrol produced a significantly greater increase in weight, percentage fat mass, intake and appetite than did the other two treatment arms, suggesting it may be the preferred agent, particularly in a palliative care setting in which weight, appetite and intake increase are desirable without regard to the composition of the body. The long-term use of these agents in people with HIV should be reviewed in the context of improved survival on highly active antiretroviral therapy regimens.