Biomedical subjects

D E Larson

Publications and source records attributed to D E Larson.

At least 19 recordsLinked to original sources

PubMed2002

Evidence for electron acceleration up to approximately 300 keV in the magnetic reconnection diffusion region of earth's magnetotail.

We report direct measurements of high-energy particles in a rare crossing of the diffusion region in Earth's magnetotail by the Wind spacecraft. The fluxes of energetic electrons up to approximately 300 keV peak near the center of the diffusion region and decrease monotonically away from this region. The diffusion region electron flux spectrum obeys a power law with an index of -3.8 above approximately 2 keV, and the electron angular distribution displays strong field-aligned bidirectional anisotropy at energies below approximately 2 keV, becoming isotropic above approximately 6 keV. These observations indicate significant electron acceleration inside the diffusion region. Ions show no such energization.

Journal Article↗

PubMed2000

Dexamethasone stimulates ribosomal protein L32 gene transcription in rat myoblasts.

Incubation of rat L6 myoblasts for 24 h with 10(-7) M dexamethasone, a glucocorticoid analogue, resulted in a 2.5-fold increase in the rate of ribosomal protein L32 (rpL32) gene transcription with a corresponding increase in the level of rpL32 mRNA. The increased rate of transcription was accompanied by a dramatic enhancement in binding of the delta, but not beta and gamma, factors to the rpL32 gene promoter as measured by gel mobility shift assays. This increased binding reflects a change in the activity of the delta factor since its level is unchanged by dexamethasone treatment. The presence of the glucocorticoid analogue RU38486 reversed the stimulating effect of dexamethasone on rpL32 gene transcription and binding of the delta factor to the delta element. These results suggest that the mechanism which enhances rpL32 gene transcription in dexamethasone-treated rat L6 myoblasts involves glucocorticoid-receptor mediated changes in the activity of the delta factor.

Animals↗

PubMed2000

Energy expenditure and free-living physical activity in black and white women: comparison before and after weight loss.

BACKGROUND: The prevalence of obesity is higher in black than in white women. Differences in energy economy and physical activity may contribute to this difference. OBJECTIVE: The objective of this study was to compare free-living energy expenditure and physical activity in black and white women before and after weight loss. DESIGN: Participants were 18 white and 14 black women with body mass indexes (in kg/m(2)) between 27 and 30. Diet, without exercise, was used to achieve a weight loss of >/=10 kg and a body mass index <25. After 4 wk of energy balance in overweight and normal-weight states, body composition was assessed by using a 4-compartment model, sleeping and resting energy expenditures were assessed by using a chamber calorimeter, physiologic stress of exercise and exercise economy were measured by using standardized exercise tasks, and daily energy expenditure was assessed by using doubly labeled water. RESULTS: Weight loss averaged 12.8 kg. Sleeping and resting energy expenditures decreased in proportion to changes in body composition. Weight reduction significantly improved physiologic capacity for exercise in both groups of women, making it easier for them to be physically active. Black women had lower body composition-adjusted energy requirements than did white women-both before and after weight loss-during sleep (9% lower, 519 kJ/d; P < 0.001), at rest (14% lower, 879 kJ/d; P < 0.001), during exercise (6% lower; P < 0. 05), and as a daily total (9% lower, 862 kJ/d; P < 0.06). By contrast, free-living physical activity was similar between the groups. CONCLUSIONS: Weight-reduced women had metabolic rates appropriate for their body sizes. Black women had lower resting and nonresting energy requirements in both overweight and normal-weight states than did white women and did not compensate with greater physical activity, potentially predisposing them to greater weight regain.

Absorptiometry, Photon↗

PubMed1998

A role for high intensity exercise on energy balance and weight control.

The objective of this commentary is to remark on the impact, exercise intensity has on energy expenditure and its potential for body weight control. Exercise intensity can favorably impact on energy expenditure in a number of ways. First, exercise-associated energy expenditure is increased by decreasing exercise efficiency and increasing work rate. Second, resistance training that increases muscle mass, in turn increases resting energy expenditure. Third, aerobic exercise > 70% VO2max, increases resting energy expenditure separate from any change in muscle mass. High-intensity exercise training has the added benefit of improving fitness, thus making low-intensity exercise less difficult and more easily tolerated. Although continuous intense exercise is difficult to maintain for extended periods of time, intense interval exercise can be easily endured and may be an important adjunct to lifestyle modifications for body weight control.

Basal Metabolism↗

PubMed1998

Topology of recombinant rat upstream binding factor.

Transmission electron microscopy and single particle electron crystallography were employed to reconstruct high-quality projection images of a recombinant, acidic tail deficient form of rat upstream binding factor. The upstream binding factor was found to be dimeric and approximately 10 nm in diameter with a central region of low density. Distinct nodes were observable, of size and spacing consistent with being HMG boxes 3 and 4. The dimerisation domain seemed most probably to be located in the internal region of the structure.

Animals↗

PubMed1997

GA-binding protein is involved in altered expression of ribosomal protein L32 gene.

Differentiation of BC3H1 myoblasts to myocytes is accompanied by a 67% drop in the rate of rpL32 gene transcription. Addition of high concentrations of serum to resting myocyte populations stimulates cell growth and subsequent dedifferentiation to proliferating myoblasts with a return to the normal rate of rpL32 gene transcription. During these growth rate changes the binding activities of previously identified factors (beta, gamma, delta) which interact with the rpL32 gene promoter were examined by mobility shift assays. Binding of the beta factor (an Ets related protein) to an oligonucleotide containing the beta element was reduced significantly in myocyte nuclear extracts, but subsequent dedifferentiation increased binding within 30 min in either the presence or absence of the cycloheximide. Binding of the gamma and delta factors to their respective elements changed only slightly during these processes. Dephosphorylation of either myoblast or myocyte extracts resulted in increased binding of the beta factor suggesting that binding activity of the beta factor is modulated by phosphorylation during the changes in BC3H1 myoblasts growth rate. In addition, mobility shift assays with recombinant GABP alpha and beta proteins and their specific antibodies revealed that GABP proteins bind to the rpL32 gene promoter in a sequence dependent manner, and that similar proteins are present in BC3H1 myoblast/myocyte extracts. These results support the premise that the GABP heterodimer is the rpL32 beta factor. Furthermore, during BC3H1 myoblast differentiation and dedifferentiation neither the levels of the GABP alpha and beta proteins nor their respective mRNAs change. These results suggest that GABP is a constitutively expressed protein and is involved in regulating rpL32 gene by post-transcriptional modifications.

Animals↗

PubMed1997

Cross-validation of prediction equations for resting energy expenditure in young, healthy children.

OBJECTIVE: To examine the accuracy of several prediction equations for resting energy expenditure (REE) in children. DESIGN: REE was measured in 113 prepubertal children (60 girls and 53 boys aged 3.9 to 7.8 years old, weighing 14.7 to 30.0 kg) using indirect calorimetry and compared with values estimated from the prediction equations of Altman and Dittmer, The Food and Agriculture Organization/World Health Organization/United Nations University (FAO/WHO/UNU), Maffeis et al, and Harris and Benedict. STATISTICAL ANALYSIS: Measured REE (MREE) was compared with predicted REE (PREE) by means of regression analysis. Prediction equations were considered accurate if the regression of MREE vs PREE was not significantly different from the line of identity (slope=1.0; intercept=0). Precision was assessed by the multiple correlation coefficient of the regression of MREE vs PREE. RESULTS: MREE was 938+/-119 kcal/day, and PREE was 1,057+/-224 kcal/day for the Altman and Dittmer equations, 956+/-84 kcal/day for the FAO/WHO/UNU equations, 948+/-64 kcal/day for the equations of Maffeis et al, and 954+/-102 kcal/day for the Harris-Benedict equations. The regression of MREE vs PREE was significantly different from the line of identity for all prediction equations except the FAO/WHO/UNU equations (slope=0.96, P=.735; intercept=-15 kcal/day, P=.885 for girls and slope=1.08, P=.635; intercept=-62 kcal/day, P=.635 for boys). None of the equations was precise for MREE vs PREE (for all, R2<.6). For the FAO/WHO/UNU equations, less than half of the predictions were within +/-50 kcal/day but 99% were within 200 kcal/day. CONCLUSION: Most prediction equations for REE in children do not accurately or precisely estimate REEs. The exception is the FAO/WHO/UNU equations, which are reasonably accurate and precise for practical purposes.

Calorimetry, Indirect↗

PubMed1997

Ad libitum food intake in humans after manipulation of glycogen stores.

It is controversial whether food intake in humans is under day-to-day regulation to maintain constant body glycogen stores. In eight white males with a mean (+/-SD) age of 30 +/- 4 y, body weight of 82 +/- 20 kg, and percentage body fat of 22 +/- 5%, exercise and diets were used to produce either high (HG) or low glycogen (LG) stores in a randomized crossover design. After each treatment a vastus lateralis muscle biopsy was obtained. Subsequent ad libitum food intake was measured with an automated food-selection system during 2 d in a respiratory chamber. Despite a 46 +/- 21% difference in muscle glycogen between the two treatments, ad libitum 2-d food intakes (energy, weight, or macronutrients) were similar between treatments (HG: 23.80 +/- 4.67 MJ/d; LG: 21.20 +/- 6.73 MJ/d). However, energy intake on the second day of ad libitum feeding was negatively correlated with carbohydrate balance on the first day, adjusted for the effect of total energy intake and treatment. Adjusted carbohydrate balance on day 1 only explained 9% of the variance in energy intake on day 2. The 24-h respiratory quotient on the first day after treatment was higher after the HG than after the LG treatment: 0.94 +/- 0.04 and 0.88 +/- 0.07 (P < 0.001). The findings suggest that 1) body glycogen stores play at most a minor role in short-term food intake regulation, and 2) in the short term, imbalances in glycogen stores are corrected by adjustments of macronutrient oxidation rates.

Adult↗

PubMed1996

Altered subcellular distribution of U3 snRNA in response to serum in mouse fibroblasts.

To extend our understanding of the mechanisms regulating ribosome biosynthesis during changes in cellular growth rate, the expression and subcellular distribution of U3 snRNA and one of its associated proteins, fibrillarin, were examined in mouse 3T6 fibroblasts. Altering serum concentrations produces changes in the ribosome content of the cell as reflected by total RNA levels. When exponentially growing 3T6 cells are induced to become quiescent by serum starvation, a significant downshift in U3 snRNA gene transcription occurs in parallel to a decrease in pre-rRNA synthesis. Serum stimulation results in an increase in the rate of synthesis of both U3 snRNA and pre-rRNA. However, U3 snRNA synthesis lags behind that of pre-rRNA. Furthermore, in serum-starved fibroblasts, a significant portion of the total cellular U3 snRNA appears in the cytoplasm. Following serum stimulation, a redistribution occurs and U3 snRNA is localized predominantly in the nucleolus at a level similar to that observed in exponentially growing cells. This redistribution is inhibited when RNA or protein synthesis is repressed in serum-stimulated fibroblasts by actinomycin D or cycloheximide. In contrast, the level and subcellular distribution of fibrillarin remain unchanged during serum starvation. These results suggest that during changes in ribosome production, distinct pools of U3 snRNPs exist within the cell.

Animals↗

PubMed1996

Structure of recombinant rat UBF by electron image analysis and homology modelling.

We have studied the structure of recombinant rat UBF (rrUBF), an RNA polymerase I transcription factor, by electron microscopy and image analysis of single particles contrasted with methylamine tungstate. Recombinant rat UBF appeared to be a flat, U-shaped protein with a central region of low density. In the dominant projections, 2-fold mirror symmetry was seen, consistent with the dimerization properties of this molecule, and of dimensions in agreement with the length of DNA that rat UBF protects in footprinting studies. Electron microscopy of various rrUBF-DNA complexes confirmed that our recombinant protein was fully able to bind the 45S rDNA promoter, and that it caused substantial bends in the DNA. Upon extended incubation in a droplet covered by a lipid monolayer at the liquid-air interface, rrUBF formed long filamentous arrays with a railway track appearance. This structure was interpreted to consist of overlapping rrUBF dimers 3.5 nm apart, which value would represent the thickness of the protein. Our results show rrUBF to interact with and bend the promoter DNA into a roughly 10 nm diameter superhelix. Based on all these electron microscopical results, an atomic structure was predicted by homology modelling of the HMG fingers, and connected by energy minimized intervening segments.

Animals↗

PubMed1996

Fat intake and adiposity in children of lean and obese parents.

We examined the relations between obesity in parents and fat intake in their children, and the effect of fat intake on fat mass in these children. Our heterogenous sample (-x+/-SD: 20.2+/-3.4 kg; 3.2+/-1.3kg fat mass) consisted of 56 white and 15 Mohawk children 4-7 y of age (35 girls and 36 boys). Dietary intake was assessed with the Willett food-frequency questionnaire revised for children. Body composition was measured by bioelectrical resistance and subscapular and triceps skinfold thicknesses. Physical-activity energy expenditure was estimated by the difference between total energy expenditure (measured over 14 d by the doubly labeled water method) and postprandial resting energy expenditure (measured by indirect calorimetry). Before statistical analysis, fat mass was adjusted for fat-free mass, and fat intake was adjusted for nonfat intake. There was no effect of sex or ethnicity on fat intake and no effect of ethnicity on the relation between fat intake and fat mass. Adjusted mean (+/-SE) fat intakes for the groups of children, based on parental obesity status, were as follows: 1.65+/-0.09 MJ/d (nonobese mother and father), 2.58+/-0.10 MJ/d (obese father, nonobese mother), and 2.79+/-0.10 MJ/d (obese mother and father). We found an influence of maternal obesity on dietary fat intake in children (P=0.052) and a significant correlation between fat mass and fat intake in boys (r=0.48, P<0.01) but not in girls after adjustment for physical-activity energy expenditure. Our data suggest that 1)mothers may contribute to the development of obesity in children by influencing their dietary fat intake, and 2) dietary fat intake contributes to obesity in boys, independent of physical-activity energy expenditure.

Adipose Tissue↗

PubMed1996

Dietary fat in relation to body fat and intraabdominal adipose tissue: a cross-sectional analysis.

Numerous studies report positive links between dietary fat and adiposity. However, the relation between fat intake and intraabdominal adipose tissue (IAAT), a risk factor for cardiovascular disease and diabetes, is not known. We therefore evaluated the association between dietary fat and adipose tissue stores in 135 white men aged 44 +/- 10 y (mean+/- SD: weight, 86 +/- 14 kg; body fat, 23 +/- 8%) and in 214 white women aged 45 +/- 14 y (weight, 64 +/- 12 kg; body fat, 33 +/- 10%). Dietary intake was estimated from 3-d food records, body composition from hydrostatic weighing, IAAT and subcutaneous abdominal adipose tissue (SCAAT) by computed tomography, and physical activity by using the Baecke Questionnaire. After adjustment for fat-free mass, sex, age, physical activity, and nonfat energy intake, fat intake was weakly correlated with fat mass, explaining only 2% of the variance (partial R2 = 0.018, P < 0.01). In a separate model that evaluated type of fat, saturated fat was positively related (partial R2 = 0.025, P < 0.01) to fat mass after adjustment for fat-free mass, sex, age, physical activity, and nonfat energy intake whereas polyunsaturated fat intake was negatively related (partial R2 = 0.007, P = 0.056). On the basis of partial correlation analyses, dietary fat was also associated with SCAAT adjusted for nonfat energy intake and IAAT (partial R2 = 0.014, P < 0.01), but not IAAT adjusted for nonfat energy intake and SCAAT. However, the association between dietary fat and adjusted SCAAT was not significant after further adjustment for sex, age, and physical activity. Thus, results of this cross-sectional analysis suggest that dietary fat independently plays a very minor role in increasing overall adiposity and does not specifically influence fat accretion in the intraabdominal region.

Adipose Tissue↗

PubMed1996

Effects of glucocorticoids on energy metabolism and food intake in humans.

The effect of glucocorticoid administration on energy metabolism and food intake was studied in 20 healthy, nondiabetic Caucasian male volunteers [27 +/- 5 (SD) yr, 72 +/- 9 kg, 20 +/- 7% body fat] randomly and blindly assigned to glucocorticoid (methylprednisolone, METH; n = 10) or placebo (PLAC; n = 10) treatment. Each subject was studied twice: during a weight maintenance diet and during ad libitum food intake. Energy metabolism was measured by indirect calorimetry and food intake by an automated food-selection system. Twenty-four-hour urinary norepinephrine excretion (24-h NE) was used as an estimate of sympathetic nervous system activity. During weight maintenance, METH intravenous infusion (125 mg/30 min) increased energy expenditure compared with PLAC, and after 4 days of oral therapy, METH (40 mg/day) decreased 24-h NE and increased energy expenditure compared with PLAC. During ad libitum food intake, after 4 days of METH (40 mg/day) or PLAC oral therapy, both groups increased their energy intake over weight maintenance, but the increase was significantly larger in the METH group compared with the PLAC group (4,554 +/- 1,857 vs. 2,867 +/- 846 kcal/day; P = 0.04). Our data suggest that therapeutic doses of glucocorticoids induce obesity mostly by increasing energy intake, an effect which may be related to the ability of glucocorticoids to act directly or indirectly on the central regulation of appetite.

Administration, Oral↗

PubMed1995

Thermic effect of food in humans: methods and results from use of a respiratory chamber.

During the past two decades, many investigators have measured the thermic effect of food (TEF) in humans and have speculated on its role in the development of obesity. In this study we compared different ways of computing TEF from daily energy expenditure measurements in a respiratory chamber, evaluated the determinants of TEF, and more importantly assessed for the first time the relation between TEF and change in body weight. In 471 subjects, TEF was 1697 +/- 857 kJ/d (mean +/- SD), ie, 18 +/- 9% of energy intake. In 114 subjects studied more than once, intraindividual TEF variability was very high (CV = 48%). TEF correlated positively with the level of spontaneous physical activity (SPA) and negatively with fasting plasma glucose and insulin concentrations. TEF correlated inversely with age (males only) and body weight, percent body fat, and waist-to-hip ratio (females only). The level of SPA and fasting plasma glucose concentration were the only significant determinants of TEF, explaining 15% of its variance. In 137 subjects in whom body weight was measured > or = 6 mo after TEF measurement (mean follow-up duration of 2.9 +/- 1.7 y), a low TEF was not predictive of body weight gain. We conclude that, despite the low reproducibility of TEF from use of a respiratory chamber, data in a large number of subjects suggest that TEF is increased by higher SPAs and that insulin resistance is associated with a low TEF. More important, longitudinal data indicate that the variability in TEF is not associated with changes in body weight.

Adolescent↗

PubMed1995

Energy metabolism in weight-stable postobese individuals.

A low metabolic rate for a given body size and body composition and a low ratio of fat to carbohydrate oxidation predict body weight gain. Such metabolic traits could also explain, in part, the propensity of previously obese (postobese) individuals to regain weight after dieting. We studied 11 postobese volunteers (4 males, 7 females; aged 43 +/- 13 y, weighing 80.6 +/- 10.2 kg, with 30 +/- 7% body fat; x +/- SD) who lost 57 +/- 38 kg (23-139 kg) over 14 +/- 12 mo (6-48 mo) on various diet programs and had maintained this weight loss for > or = 2 mo (2-72 mo; 21 +/- 27 mo). After > or = 2 d of a weight-maintenance diet on a metabolic ward, 24-h energy expenditure and ratio of fat to carbohydrate oxidation were measured in a respiratory chamber. Compared with a control group (n = 110) with similar physical characteristics (aged 43 +/- 14 y, weighing 79.5 +/- 11.4 kg, with 30 +/- 12% body fat), [sequence: see text] postobese individuals had similar energy expenditures adjusted for fat-free mass, fat mass, age, and sex, but significantly higher respiratory quotients over 24 h (0.883 +/- 0.026 compared with 0.863 +/- 0.024, P < 0.01) and during sleep, 10 h after the last meal (0.894 +/- 0.063 compared with 0.845 +/- 0.055). These results suggest that postobese individuals have low rates of fat oxidation that may explain their propensity to regain weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1995

Ad libitum food intake on a "cafeteria diet" in Native American women: relations with body composition and 24-h energy expenditure.

Epidemiologic studies consistently report associations between obesity and dietary fat but not total energy intake. We measured ad libitum food intake in a laboratory setting and evaluated its relation to body weight and composition, energy expenditure, and macronutrient utilization in 28 women of Pima-Papago heritage (aged 27 +/- 7 y, 85.3 +/- 19.0 kg, 44 +/- 6% body fat; means +/- SD). All women were studied during the follicular phase of the menstrual cycle. After a 4-d weight-maintenance period, the volunteers selected their food for 5 d from computerized vending machines offering a variety of familiar and preferred foods, ie, a "cafeteria diet". Twenty-four-hour energy expenditure and substrate oxidation were measured in a respiratory chamber on the 4th d o weight maintenance and the 5th d of ad libitum intake. Average ad libitum intake was 13,732 +/- 4238 kJ/d (11 +/- 1% protein, 40 +/- 1% fat, 49 +/- 4% carbohydrate), ie, moderate overeating by 27 +/- 37% above weight maintenance requirements (range: -27% to 124%). Percent body fat correlated with daily energy intake (r = 0.53, P < 0.01), the degree of overeating (r = 0.41, P < 0.05), and the selection of a diet higher in fat and lower in carbohydrate (r = 0.70 and r = -0.63, respectively, P < 0.001). Excess carbohydrate intake caused an increase in carbohydrate oxidation (r = 0.51, P < 0.01), whereas excess fat intake resulted in a decrease in fat oxidation (r = -0.53, P < 0.01) and thus a positive fat balance of 85 +/- 65 g/d. The positive relations among degrees of obesity, dietary fat intake and overeating, and the fact that dietary fat does not induce fat oxidation, support the hypothesis that dietary fat promotes obesity in women.

Adult↗

PubMed1995

Spontaneous overfeeding with a 'cafeteria diet' in men: effects on 24-hour energy expenditure and substrate oxidation.

OBJECTIVE: To investigate the relationship between obesity and ad libitum food intake (quantity and composition) and to assess the impact of ad libitum food intake on energy expenditure and macronutrient oxidation. DESIGN: Male volunteers were first fed a weight maintaining diet for at least 4 days before selecting their food for the next 5 days from two computerized vending machines offering a variety of familiar, palatable foods. 24-h energy expenditure (24EE) and substrate oxidation were measured in a respiratory chamber on the last day of each weight maintenance and ad libitum intake periods. SETTING: Ten day admission on a metabolic research ward. SUBJECTS: Thirty-four non-diabetic Pima Indian males covering a wide range of body weight and body composition (30 +/- 8 y, 102.1 +/- 30.2 kg, 34 +/- 9% body fat, mean +/- s.d.). RESULTS: Weight maintenance requirements averaged 2913 +/- 342 kcal/d. Energy intake during the ad libitum period increased to 4550 +/- 921 kcal/d (12 +/- 1% protein, 40 +/- 4% fat, 48 +/- 4% carbohydrate) i.e., a spontaneous overeating by 54 +/- 32% above weight maintenance requirement, resulting in a 0.9 +/- 1.0 kg body weight gain. Neither the composition of the selected diet nor the degree of overeating was associated with physical characteristics, such as body weight and body composition. When compared with baseline, spontaneous overeating on day 5 was associated with a 396 +/- 233 kcal/d increase in 24EE, a 607 +/- 503 kcal/d increase in carbohydrate oxidation, a 214 +/- 392 kcal/d decreased in lipid oxidation (P < 0.01), and no change in protein oxidation. Increased carbohydrate oxidation correlated with the excess carbohydrate intake (r = 0.69, P = 0.0001) accounting for 68 +/- 13% (mean +/- s.e.e.) of the excess, whereas excess fat intake was not oxidized. CONCLUSION: In response to spontaneous overfeeding on a mixed 'cafeteria diet', excess carbohydrate intake is oxidized, suggesting a physiological control of carbohydrate stores, whereas excess fat intake is channeled toward fat stores. None of the observed changes were related to indices of obesity.

Adult↗

PubMed1995

Racial difference in body core temperature between Pima Indian and Caucasian men.

A low body temperature is associated with a low metabolic rate for a given body size and body composition. These two traits might have been assets in the history of a population subjected to cycles of feast and famine, but became part of an obesity-prone syndrome in our westernized society characterized by plenty of food and a sedentary lifestyle. We tested whether Pima Indians have lower body temperatures than Caucasians, a trait which might partly explain the high prevalence of obesity in this population. Twenty-five Pima Indian (28 +/- 6 yrs, 87.8 +/- 22.8 kg, 29 +/- 9% body fat) and 25 Caucasian (30 +/- 5 yrs, 80.7 +/- 18.4 kg, 22 +/- 11% body fat) men had body core temperatures measured by telemetry for 24 h while in a respiratory chamber. Mean daily body core temperature was 36.93 +/- 0.12 and 36.90 +/- 0.22 degrees C in Pima Indians and Caucasians, respectively. Since body core temperature during sleep (SLBCT) correlated with percentage body fat, a subset of 10 Pima Indians and 10 Caucasians were pair-matched for body weight and percentage body fat. In this group, SLBCT was lower in Pima Indians than in Caucasians (36.45 +/- 0.10 vs 36.65 +/- 0.27 degrees C; P < 0.01) and, ethnic group accounted for 20% of the variance in SLBCT (P < 0.01). Surprisingly, the lower SLBCT was not associated with a low metabolic rate and therefore does not seem to play a role in the etiology of obesity in Pima Indians.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗