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Biomedical subjects

D B Allison

Publications and source records attributed to D B Allison.

At least 55 records · Page 3Linked to original sources
PubMed2001

Gender differences in the relationship between personality dimensions and relative body weight.

OBJECTIVE: The relationship between body mass index (BMI: kg/m(2)) and personality seems to differ for men and women, although these effects may be driven by the extremes of the BMI distribution. It is unclear whether these associations exist for most individuals in the relatively normal range of BMI scores, excluding the thinnest and heaviest extremes in the population. We tested the association of BMI with neuroticism, extraversion, and psychoticism with a trimmed BMI sample. RESEARCH METHODS AND PROCEDURES: Using a cross-sectional design, we tested the association of BMI with the aforementioned psychological variables in a British population-based sample. Participants were 7889 adult men and women (30 to 50 years old) selectively sampled from four counties in west England. Participants reported their height and weight and completed the Eysenck Personality Inventory (EPQ). We tested the association of BMI with the EPQ subscales among individuals with BMI >or=19.16 kg/m(2) and <or=37.78 kg/m(2), i.e., the approximate 5th and 95th percentiles. RESULTS: Despite elimination of extreme BMIs, different associations between BMI and EPQ subscales emerged for men and women. Among women, increasing BMI was significantly associated with increased neuroticism and reduced extraversion. Among men, increasing BMI was associated with increased extraversion and psychoticism. In all cases, the magnitude of the association was very small. DISCUSSION: Increasing BMI was associated with potentially poorer adjustment among women but better adjustment among men. These findings are consistent with recent reports and, taken together, suggest that these patterns are not accounted for solely by the extremes of the BMI distribution.

Adult↗
PubMed2001

A twin study of weight loss and metabolic efficiency.

OBJECTIVE: To assess the genetic contribution to determinants of therapeutic weight loss in obese female identical twins. DESIGN: Subjects were studied for 40 days on an inpatient unit in three phases: 7 baseline days; 28 days of weight reduction by a very low calorie diet (1.6 MJ per day); and 5 days after weight reduction. SUBJECTS: Fourteen pairs of premenopausal obese female identical twins (age: 39.0+/-1.7 y; body weight (BW): 93.9+/-21.2 kg; body mass index (BMI): 34.2+/-7.8 kg/m2). MEASUREMENTS: : Body composition by hydrodensitometry and resting metabolic rate by indirect calorimetry were assessed before and after weight loss. RESULTS: : There was great variability among pairs in loss of weight (5.9-12.4 kg) and body fat (3.1-12.4 kg). By contrast, the intraclass correlation (ICC) within twin pairs was 0.85, P<0.001 for weight and 0.88, P<0.001 for body fat. A measure of metabolic efficiency, calculated as the difference between 'estimated' and 'measured' energy deficit showed high intrapair correlation (ICC=0.77; P<0.001). CONCLUSIONS: The high correlation in metabolic efficiency within twin pairs in response to therapeutic weight loss suggests a strong genetic contribution.

Adult↗
PubMed2001

Is obesity a disease?

BACKGROUND: There is disagreement about whether obesity should be considered a disease, as can be seen by inconsistent usage and the advocacy of conflicting views in popular and scholarly articles. However, neither writers who refer to obesity as a disease nor those who question whether it is a disease have generally provided a definition of disease and then offered evidence that obesity does or does not fit the definition. METHOD: The characteristics of obesity were examined to determine whether they fit the common and recurring elements of definitions of disease taken from a sample of authoritative English language dictionaries. FINDINGS AND INTERPRETATIONS: Obesity, defined as a body mass index (BMI, kg/m(2)) or percentage body fat in excess of some cut-off value, though clearly a threat to health and longevity, lacks a universal concomitant group of symptoms or signs and the impairment of function which characterize disease according to traditional definitions. While it might nevertheless be possible to achieve a social consensus that it is a disease despite its failure to fit traditional models of disease, the merits of such a goal are questionable. Labeling obesity a disease may be expedient but it is not a necessary step in a campaign to combat obesity and it may be interpreted as self-serving advocacy without a sound scientific basis.

Body Mass Index↗
PubMed2001

The genetic epidemiology of thinness.

Most genetic research in the area of human obesity asks the question 'Why are certain people obese?' Considerably less attention has been paid to the question of why certain people are not obese, particularly given the obesogenic environment that permeates the western culture. We present data from human and animal studies and evolutionary arguments supporting the notion that genetic studies of thinness or obesity resistance may yield important and complementary findings to genetic studies of obesity. We offer strategies for further refining the definition of thinness, weigh the advantages and disadvantages of potential sampling strategies and suggest candidate genes for thinness or obesity resistance.

Animals↗
PubMed2001

Metabolic disharmony and mortality.

The concept of 'metabolic harmony' is introduced and conceptualized as the state in which indices of metabolic activity (i.e., serum glucose, cholesterol, systolic and diastolic blood pressure, body mass index) within an individual attain their expected values given the individual values on related variables. Its complement, 'metabolic disharmony' (i.e., the extent to which an individual's 'profile' of metabolic variables is jointly unusual in relation to their expected values) is operationalized via Mahalanbis' D(2 )statistic calculated on these indices of metabolic activity (plus age and sex). Analysis of a large (N = 5209) longitudinal (32 years) cohort study shows that, independent of the linear and quadratic effects of the aforementioned metabolic variables, the disharmony index (DI) significantly and strongly predicted hazard of death (chi(2)(1) = 20.05, P < 0.00005). That is, each 10 percentile increase in DI was associated with a 6.9% increase in the hazard rate. The association of DI to hazard rate was not materially altered when potential confounders (e.g., smoking status) were added to the model or when all subjects were included by imputing missing data. These results demonstrate that metabolic disharmony is associated with, and may cause, an increased hazard of death.

Death↗
PubMed2001

Alternative treatments for weight loss: a critical review.

"Nontraditional" or "alternative" treatments are extremely popular, especially with respect to obesity and body composition. Although such treatments are widely used, it is not clear that these are supported by the existing data in the peer-reviewed literature. Herein, we review the data on 18 methods/products advocated as potential anti-obesity/fat-reducing agents. We have found that none have been convincingly demonstrated to be safe and effective in two or more peer-reviewed publications of randomized double-blind placebo-controlled trials conducted by at least two independent laboratories. Nevertheless, some have plausible mechanisms of action and encouraging preliminary data that are sufficiently provocative to merit further research.

Anti-Obesity Agents↗
PubMed2001

Body weight and cancer screening among women.

Obesity increases cancer risk, yet small-scale surveys indicate that obese women delay or avoid cancer screening even more so than do nonobese women. We sought to estimate the association between body mass index (BMI) (kg/m(2)) and delayed cancer screening among adult women in a population-based survey. Subjects were women classified by BMI as underweight (<18.5), desirable weight (18.5-24.9), overweight (25-29.9), obese class I (30-34.9), obese class II (35-39.9), and obese class III (> or =40). Outcome measures were intervals (0 for < or =2 years versus 1 for >2 years) since most recent screening for Papanicolaou (Pap) smear, mammography, and clinical breast examination (CBE). Adjusting for age, race, smoking, and health insurance, we observed J-shaped associations between BMI and screening. Compared with desirable weight women, underweight women (odds ratios [OR] = 1.21, 95% confidence interval [95% CI] 1.09-1.34), overweight women (OR = 1.13, 95% CI 1.07-1.18), and obese women (OR range 1.22-1.69) were significantly more likely to delay Pap smear testing for >2 years. Underweight (OR = 1.32, 95% CI 1.13-1.54), obesity class I (OR = 1.12, 95% CI 1.02-1.23), and obesity class III women (OR = 1.32, 95% CI 1.10-1.54) were more likely to delay mammography, and overweight (OR = 1.10, 95% CI 1.01-1.19), obesity class I (OR = 1.18, 95% CI 1.08-1.30), and obesity class III women (OR = 1.47, 95% CI 1.23-1.75) were more likely to delay CBE. White women were more likely to delay CBE as a function of BMI than were non-white women. Weight may be an important correlate of cancer screening behavior, particularly for white women.

Adult↗
PubMed2001

Pooling analysis of genetic data: the association of leptin receptor (LEPR) polymorphisms with variables related to human adiposity.

Analysis of raw pooled data from distinct studies of a single question generates a single statistical conclusion with greater power and precision than conventional metaanalysis based on within-study estimates. However, conducting analyses with pooled genetic data, in particular, is a daunting task that raises important statistical issues. In the process of analyzing data pooled from nine studies on the human leptin receptor (LEPR) gene for the association of three alleles (K109R, Q223R, and K656N) of LEPR with body mass index (BMI; kilograms divided by the square of the height in meters) and waist circumference (WC), we encountered the following methodological challenges: data on relatives, missing data, multivariate analysis, multiallele analysis at multiple loci, heterogeneity, and epistasis. We propose herein statistical methods and procedures to deal with such issues. With a total of 3263 related and unrelated subjects from diverse ethnic backgrounds such as African-American, Caucasian, Danish, Finnish, French-Canadian, and Nigerian, we tested effects of individual alleles; joint effects of alleles at multiple loci; epistatic effects among alleles at different loci; effect modification by age, sex, diabetes, and ethnicity; and pleiotropic genotype effects on BMI and WC. The statistical methodologies were applied, before and after multiple imputation of missing observations, to pooled data as well as to individual data sets for estimates from each study, the latter leading to a metaanalysis. The results from the metaanalysis and the pooling analysis showed that none of the effects were significant at the 0.05 level of significance. Heterogeneity tests showed that the variations of the nonsignificant effects are within the range of sampling variation. Although certain genotypic effects could be population specific, there was no statistically compelling evidence that any of the three LEPR alleles is associated with BMI or waist circumference in the general population.

Adipose Tissue↗
PubMed2001

Calorie restriction and skeletal mass in rhesus monkeys (Macaca mulatta): evidence for an effect mediated through changes in body size.

Little is known regarding the effects of prolonged calorie restriction (CR) on skeletal health. We investigated long-term (11 years) and short-term (12 months) effects of moderate CR on bone mass and biochemical indices of bone metabolism in male rhesus monkeys across a range of ages. A lower bone mass in long-term CR monkeys was accounted for by adjusting for age and body weight differences. A further analysis indicated that lean mass, but not fat mass, was a strong predictor of bone mass in both CR and control monkeys. No effect of short-term CR on bone mass was observed in older monkeys (mean age, 19 years), although young monkeys (4 years) subjected to short-term CR exhibited slower gains in total body bone density and content than age-matched controls. Neither biochemical markers of bone turnover nor hormonal regulators of bone metabolism were affected by long-term CR. Although osteocalcin concentrations were significantly lower in young restricted males after 1 month on 30% CR in the short-term study, they were no longer different from control values by 6 months on 30% CR.

Animals↗
PubMed2001

Genetic variability in responses to caloric restriction in animals and in regulation of metabolism and obesity in humans.

Panel 5 focused on genetic factors that might mediate or moderate the effects of caloric restriction (CR) on longevity. Panel members stated that currently there is limited information directly addressing these issues. Therefore, they focused attention on what studies could be done. In addition, the panel believed that certain conceptual issues merited clarification and focused attention on this issue. Human studies and studies of nonhuman model organisms were discussed. The panel found at least three reasons why it would be valuable to find genes that influence the (putative) longevity-promoting effect of CR in humans. Such knowledge would offer: (a) the ability to predict individual responses to CR; (b) increased understanding of physiological mechanisms; and (c) the potential to develop mechanism-based interventions to promote longevity or healthy aging. In addition, the panel emphasized several macro-level recommendations regarding research strategies to avoid, research strategies to emphasize, and resources needing development.

Animals↗
PubMed2001

Epidemiologic data on the relationships of caloric intake, energy balance, and weight gain over the life span with longevity and morbidity.

Animal experiments have shown that calorically restricted (CR) animals weigh less and live longer than their ad libitum-fed peers. Are these observations applicable to human beings? This is an important question because the prevalence of obesity in America has increased markedly over recent years. We examine whether there are physiologic effects that occur with CR in humans that could plausibly explain the observed longevity of laboratory animals associated with CR. We also review epidemiologic data from observational and interventional studies on the relationships of caloric intake, energy balance, and weight gain with age-related diseases and longevity. Additionally, data on whether long-term, sustained maintenance of weight loss is feasible, as well as the degree of CR achieved in clinical trials, are summarized. Finally, we provide recommendations regarding further epidemiologic research that will help clarify unanswered questions in these areas.

Energy Intake↗
PubMed2001

Changes in blood chemistry and hematology variables during aging in captive rhesus macaques (Macaca mulatta).

Identifying changes with age in physiological variables of captive nonhuman primates will aid in the proper treatment and clinical diagnosis of these animals, as well as enhance our understanding of nonhuman primate models for human aging. Information for 33 physiological variables was obtained from the Primate Aging Database, a multi-centered database being developed for clinical and research use. Using multiple regression analyses, we investigated the relationship of age to hematological variables, blood chemistry and body weight in 345 captive rhesus monkeys (age range 7-30 years) from three different primate research facilities. The analyses revealed that 15 of these variables show a significant relationship with chronological age and are altered in older as compared with adult animals. Here we present the first phase of a project that will: a) identify changes with age in physiological variables among adult captive rhesus macaques; and b) characterize normative values for the aging rhesus population.

Aging↗
PubMed2001

Dietary restriction and glucose regulation in aging rhesus monkeys: a follow-up report at 8.5 yr.

In a longitudinal study of the effects of moderate (70%) dietary restriction (DR) on aging, plasma glucose and insulin concentrations were measured from semiannual, frequently sampled intravenous glucose tolerance tests (FSIGTT) in 30 adult male rhesus monkeys. FSIGTT data were analyzed with Bergman's minimal model, and analysis of covariance revealed that restricted (R) monkeys exhibited increased insulin sensitivity (S(I), P < 0.001) and plasma glucose disappearance rate (K(G), P = 0.015), and reduced fasting plasma insulin (I(b), P < 0.001) and insulin response to glucose (AIR(G), P = 0.023) compared with control (C; ad libitum-fed) monkeys. DR reduced the baseline fasting hyperinsulinemia of two R monkeys, whereas four C monkeys have maintained from baseline, or subsequently developed, fasting hyperinsulinemia; one has progressed to diabetes. Compared with only the normoinsulinemic C monkeys, R monkeys exhibited similarly improved FSIGTT and minimal-model parameters. Thus chronic DR not only has protected against the development of insulin resistance in aging rhesus monkeys, but has also improved glucoregulatory parameters compared with those of otherwise normoinsulinemic monkeys.

Aging↗
PubMed2001

Effects of contingent television on physical activity and television viewing in obese children.

OBJECTIVE: Elevated television (TV) viewing and physical inactivity promote obesity in children. Thus, changes in physical activity and sedentary behavior seem critical to treating childhood obesity. PRESENT STUDY: Using a randomized, 2-arm design, this pilot study tested the effects of contingent TV on physical activity and TV viewing in 10 obese children. TV viewing was contingent on pedaling a stationary cycle ergometer for experimental participants but was not contingent on pedaling for control participants. The study was conducted over 12 weeks, including a 2-week baseline period. RESULTS: Multivariate analyses indicated that the intervention significantly increased pedaling and reduced TV-viewing time. During the treatment phase, the experimental group pedaled 64.4 minutes per week on average, compared with 8.3 minutes by controls. The experimental group watched 1.6 hours of TV per week on average, compared with 21.0 hours per week on average by controls during this phase. Secondary analyses indicated that the experimental group showed significantly greater reductions in total body fat and percent leg fat. Total pedaling time during intervention correlated with greater reductions in percent body fat (r = -0.68). CONCLUSIONS: Contingencies in the home environment can be arranged to modify physical activity and TV viewing and may have a role in treating childhood obesity. Contingent TV may be one method to help achieve this goal.

Behavior Therapy↗
PubMed2001

Antipsychotic-induced weight gain: a review of the literature.

With the availability of the so-called novel antipsychotic agents, extrapyramidal symptoms are becoming decreasingly problematic for patients with schizophrenia, and simultaneously, a new symptom is emerging as a preeminent concern. This side effect is weight gain and its metabolic concomitants. This article reviews what is currently known about antipsychotic-induced weight gain, describes the magnitude of the problem, briefly touches on mechanisms of action, and addresses the correlation of interindividual variations in magnitude of weight gain. In addition, we address questions about the effects of weight gain on compliance and whether or not there is a correlation between weight gain and therapeutic efficacy. Finally, we address medical consequences of weight gain and review the literature supporting various treatment options for antipsychotic-induced weight gain. As will be seen, this is an area of research in its infancy, and much work remains to be done.

Adult↗
PubMed2001

Two novel quantitative trait loci on mouse chromosomes 6 and 4 independently and synergistically regulate plasma apoB levels.

An elevated plasma apolipoprotein B (apoB) level is a strong predictor of atherosclerosis and coronary heart disease. Epidemiologic and family linkage studies have suggested a genetic basis for the wide variations of plasma apoB levels in the general population. Using a human apoB transgenic (HuBTg) mouse model, we have previously shown that hepatic apoB-100 secretion is a major determinant of the high and low plasma human apoB levels in HuBTg mice of the C57BL/6 (B6) and 129/Sv (129) strains, respectively. In the present article, we present the identification of two novel quantitative trait loci (QTL) as major regulators of plasma human apoB levels in the F(2) and N(2) (backcrossed) offspring (n = 572) derived from crosses between the B6 and 129 mouse strains. These loci were designated ApoB regulator genes (Abrg), because the gene products are likely to be involved in the regulation of plasma apoB levels either directly or indirectly. The first locus, designated Abrg1, was mapped to chromosome 6 in 8-week-old male and female mice with a combined logarithm of odds ratio (LOD) score of 14 at the D6Mit55 marker ( approximately 45.9 cM). Abrg1 contributed approximately 35% of the genetic variance. The second locus, designated Abrg2, was mapped to chromosome 4 with an LOD score of 8.6 in 8-week-old male mice but an LOD score of only 2.0 in 8-week-old female mice at the D4Mit27 marker ( approximately 35 cM). Abrg2 contributed approximately 26% of the genetic variance. Epistasis between Abrg1 and Abrg2 was detected and accounted for approximately 12% of the genetic variance. The combination of these two QTL has major effects (>70%) on the regulation of plasma human apoB levels in the tested population. In summary, we have identified two novel loci that have a major role in the regulation of plasma apoB levels and are likely to regulate the secretory pathway of apoB. The human orthologs for the Abrg loci are strong candidates for human disorders characterized by altered plasma apoB levels, such as FCHL and familial hypobetalipoproteinemia.

Analysis of Variance↗