bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ethnic Differences in the Responsiveness of Adipocyte Lipolytic Activity to Insulin
Authors: Buthelezi Ernest P. , van der Merwe Maria‐Terésa , Lönnroth Peter N. , Gray I. Peter , Crowther Nigel J. 
Published: April 2008

AbstractObjective: The goal of this study was to quantify differences in lipid metabolism and insulin sensitivity in black and white subjects to explain ethnic clinicopathological differences in type 2 diabetes.Research Methods and Procedures: The in vitro lipolytic activity of adipocytes isolated from obese black and white women was measured in the presence of insulin and isoproterenol. Insulin resistance was assessed in vivo using the euglycemic hyperinsulinemic clamp technique.Results: Fasting plasma levels of insulin and nonesterified fatty acid (NEFA) in black and white women were 67 ± 5 pM vs. 152 ± 20 pM (p < 0.01) and 863 ± 93 μM vs. 412 ± 34 μM (p < 0.01), respectively. Euglycemic hyperinsulinemic clamp studies showed that obese black subjects were more insulin‐resistant than their white counterparts (glucose infusion rates: 1.3 ± 0.2 vs. 2.2 ± 0.3 mg/kg per min; p < 0.05). Isolated adipocytes from white women were more responsive to insulin than those from black women with 0.7 nM insulin causing a 55 ± 4% inhibition of isoproterenol‐stimulated lipolysis compared with 27 ± 10% in black women (p < 0.05).Discussion: The low responsiveness of adipocyte lipolytic activity to insulin in black women in the presence of a relative insulinopenia may account for the high plasma NEFA levels seen in these women, which may, in turn, account for their higher in vivo insulin resistance. High NEFA levels may also contribute to the low insulin secretory activity observed in the obese black females. These data suggest that the pathogenesis of insulin resistance and type 2 diabetes within the black obese community is strongly influenced by their adipocyte metabolism.
A Glucocorticoid Receptor Gene Marker Is Associated with Abdominal Obesity, Leptin, and Dysregulation of the Hypothalamic‐Pituitary‐Adrenal Axis
Authors: Rosmond Roland , Chagnon Yvon C. , Holm Göran , Chagnon Monique , Pérusse Louis , Lindell Kajsa , Carlsson Björn , Bouchard Claude , Björntorp Per 
Published: April 2008

AbstractObjective: Abdominal obesity has a key role in the pathogenesis of prevalent and serious diseases and has been shown to be associated with an altered hypothalamic‐pituitary‐adrenal (HPA) axis function, which is regulated by endocrine feedback mediated via hippocampal glucocorticoid receptors (GR).Research Methods and Procedures: We examined the HPA axis function by repeated salivary samples for the assessment of cortisol, as well as other endocrine, anthropometric, metabolic, and circulatory variables in middle‐aged Swedish men (n = 284). With the restriction enzyme BclI, variants of the GR gene (GRL) locus were identified and two alleles with fragment lengths of 4.5 and 2.3 kilobases (kb) were detected.Results: The observed frequencies were 40.1% for the 2.3‐ and 2.3‐kb, 46.2% for the 4.5‐ and 2.3‐kb, and 13.7% for the 4.5‐ and 4.5‐kb genotypes. The larger allele (4.5 and 4.5 kb) was associated with elevated body mass index (BMI; p < 0.001), waist‐to‐hip circumference ratio (p = 0.015), abdominal sagittal diameter (p = 0.002), leptin (p < 0.001), and systolic blood pressure (borderline, p = 0.058). The 4.5‐ and 4.5‐kb allele was associated with leptin after adjustment for BMI. Moreover, salivary cortisol values, particularly after stimulation by a standardized lunch (p = 0.040 to 0.086), were elevated in the men with the larger allele.Discussion: These results indicate that there is an association between a deficient GR function, defined as a poor feedback regulation of the HPA axis activity, and a polymorphic restriction site at the GR gene locus. An abnormal control of HPA axis function due to genetic alterations may contribute to the pathogenesis of abdominal obesity.
Increased Adipose Angiotensinogen Gene Expression in Human Obesity
Authors: van Harmelen Vanessa , Ariapart Parisa , Hoffstedt Johan , Lundkvist Inger , Bringman Sven , Arner Peter 
Published: April 2008

AbstractObjective: Adipose angiotensinogen has been suggested as a stimulator of adipose tissue growth and development. Therefore, the association of subcutaneous adipose angiotensinogen gene expression with human obesity was studied.Research Methods and Procedures: The study group consisted of 17 men, undergoing either gastric banding for obesity or elective laparoscopic cholecystectomy (7 obese, 10 non‐obese men; body mass index 22 to 51 kg/m2; age 26 to 68 years). Subcutaneous adipose angiotensinogen mRNA and 18S ribosomal RNA (reference gene) levels were measured using competitive quantitative reverse transcriptase‐polymerase chain reaction.Results: Adipose angiotensinogen mRNA expression was about two times increased in obesity. The levels of 18S rRNA did not differ between the two groups. Body weight correlated independently and positively with adipose angiotensinogen mRNA expression after adjusting for differences in age and height.Discussion: Adipose angiotensinogen gene expression is elevated in obesity in men.
Defective Dietary Induction of Uncoupling Protein 3 in Skeletal Muscle of Obesity‐Prone Rats
Authors: Weigle David S. , Levin Barry E. 
Published: April 2008

AbstractObjective: The goal of this study was to determine whether differential induction of skeletal muscle uncoupling protein 3 (UCP3) contributes to the development of diet‐induced obesity (DIO) or resistance to the development of obesity (DR) when rats are placed on a moderate fat (31%) high energy (HE) diet.Research Methods and Procedures: Gastrocnemius muscle was obtained from Sprague‐Dawley rats that were identified as DIO‐prone (n = 5) or DR (n = 5) on the basis of urinary norepinephrine excretion while consuming a chow diet. Muscle was also obtained from animals in the top tertile of weight gain (DIOHE, n = 5) and the bottom tertile of weight gain (DRHE, n = 5) after 2 weeks on the HE diet. UCP3 and actin mRNA levels were measured in all muscle samples by Northern analysis. To distinguish the effect of dietary energy content from the effect of obesity itself, we studied additional DIO and DR animals that had been returned to a chow diet for 10 weeks after consuming a HE diet for 10 weeks.Results: The muscle UCP3/actin mRNA ratio in animals that resisted the development of obesity during 2 weeks on the HE diet was 3‐fold higher than in the other groups (DRHE = 3.24 ± 0.83, DIOHE = 0.91 ± 0.20, DIO‐prone = 0.72 ± 0.15, DR = 0.63 ± 0.15; p = 0.002). However, there was no difference in muscle UCP3/actin mRNA ratios between DIO animals and DR animals that had been fed the HE diet for 10 weeks and then returned to either an ad libitum chow diet for 10 weeks (DIO = 13.8 ± 3.53, DR = 11.1 ± 3.43, p = NS) or to a restricted chow diet for 10 weeks (DIO = 11.0 ± 2.85, DR = 10.6 ± 2.20, p = NS) despite significantly greater body weight of the DIO animals.Discussion: DR animals may initially resist weight gain when placed on a HE diet through a greater induction of muscle UCP3. This induction is transient and is related more closely to dietary fat content than to body fat stores. DIO animals show no initial induction of muscle UCP3, which may contribute to their increased metabolic efficiency soon after exposure to a HE diet.
Access and Use of Medical Care among Obese Persons
Authors: Fontaine Kevin R. , Bartlett Susan J. 
Published: April 2008

AbstractThe prevalence of obesity and severe obesity is growing rapidly, along with obesity‐related comorbidities and mortality. Given the increased health risks associated with obesity, it is vital that obese persons have adequate access to, and make consistent use of, medical care services. Assuming obese persons have access to medical care that is comparable to non‐obese persons, one would expect to observe greater use of medical services among obese persons. In this article we briefly review empirical evidence of the access to and use of medical care among obese persons. Although certain subgroups that tend to have disproportionately high prevalences of obesity (i.e., low socioeconomic status, minority groups) have reduced access to care, no studies have specifically examined whether or not obese persons have the same access to health care as do their lean counterparts. With respect to use of health care services, however, obesity has been consistently linked with greater rates of utilization and increased health care expenditures. Both the increased use and cost appear to be largely a function of treating obesity‐associated comorbidities such as diabetes and hypertension. We conclude that, although it is clear that obesity is associated with both greater use and cost of medical care, the relationship between obesity and access to medical care has not been determined.
Leptin Responses to Weight Loss in Postmenopausal Women: Relationship to Sex‐Hormone Binding Globulin and Visceral Obesity
Authors: van Rossum Elisabeth F. C. , Nicklas Barbara J. , Dennis Karen E. , Berman Dora M. , Goldberg Andrew P. 
Published: April 2008

AbstractObjective: Leptin concentrations increase with obesity and tend to decrease with weight loss. However, there is large variation in the response of serum leptin levels to decreases in body weight. This study examines which endocrine and body composition factors are related to changes in leptin concentrations following weight loss in obese, postmenopausal women.Research Methods and Procedures: Body composition (DXA), visceral obesity (computed tomography), leptin, cortisol, insulin, and sex hormone‐binding globulin (SHBG) concentrations were measured in 54 obese (body mass index [BMI] = 32.0 ± 4.5 kg/m2; mean ± SD), women (60 ± 6 years) before and after a 6‐month hypocaloric diet (250 to 350 kcal/day deficit).Results: Body weight decreased by 5.8 ± 3.4 kg (7.1%) and leptin levels decreased by 6.6 ± 11.9 ng/mL (14.5%) after the 6‐month treatment. Insulin levels decreased 10% (p < 0.05), but mean SHBG and cortisol levels did not change significantly. Relative changes in leptin with weight loss correlated positively with relative changes in body weight (r = 0.50, p < 0.0001), fat mass (r = 0.38, p < 0.01), subcutaneous fat area (r = 0.52, p < 0.0001), and with baseline values of SHBG (r = 0.38, p < 0.01) and baseline intra‐abdominal fat area (r = −0.27, p < 0.06). Stepwise multiple regression analysis showed that baseline SHBG levels (r2 = 0.24, p < 0.01), relative changes in body weight (cumulative r2 = 0.40, p < 0.05), and baseline intra‐abdominal fat area (cumulative r2 = 0.48, p < 0.05) were the only independent predictors of the relative change in leptin, accounting for 48% of the variance.Discussion: These results suggest that obese, postmenopausal women with a lower initial SHBG and more visceral obesity have a greater decrease in leptin with weight loss, independent of the amount of weight lost.
Occupational Status, Cortisol Secretory Pattern, and Visceral Obesity in Middle‐aged Men
Authors: Rosmond Roland , Björntorp Per 
Published: April 2008

AbstractObjective:Despite several studies indicating that social gradients are predictive of cardiovascular mortality, the pathogenetic mechanisms remain incompletely understood.Research Methods and Procedures:A population sample of 51‐year‐old men (N= 284) was divided into a socioeconomic gradient with manual laborers, civil servants, and university graduates. Anthropometric measurements were registered. Cortisol concentrations were measured in saliva, collected repeatedly during an ordinary working day, and a low‐dose dexamethasone suppression test was performed.Results:Lower socioeconomic status was associated with visceral obesity and higher cortisol values in relation to perceived stress. However, total cortisol secretion over the day of study was not elevated. The regulation of cortisol secretion showed less plasticity and dexamethasone inhibition was less efficient in the men in the lower socioeconomic status group than in those with a higher socioeconomic status. These are known consequences of long term stress. Longer duration in low socioeconomic conditions seemed to worsen these phenomena.Discussion:It was concluded that a low socioeconomic status is associated with perturbed cortisol secretion, which is elevated in relation to perceived stress. When the hypothalamic‐pituitary‐adrenal axis is subjected to prolonged increases in cortisol elicited by chronic stress, the regulation of cortisol secretion is affected, indicating neuroendocrine dysregulations. These observations may provide a means for understanding the association of socioeconomic impairments with visceral obesity and the social inequality in risk for prevalent and serious diseases.
The Activity of the Hypothalamic‐Pituitary‐Adrenal Axis and the Sympathetic Nervous System in Relation to Waist/Hip Circumference Ratio in Men
Authors: Ljung Thomas , Holm Göran , Friberg Peter , Andersson Björn , Bengtsson Bengt‐Åke , Svensson Johan , Dallman Mary , McEwen Bruce , Björntorp Per 
Published: April 2008

AbstractObjective: To investigate possible differences, between generally and abdominally obese men, in activity and regulation of the hypothalamic‐pituitary‐adrenal (HPA) axis and the sympathetic nervous system.Research Methods and Procedures: Fifty non‐diabetic, middle‐aged men were selected to obtain two groups with similar body mass index (BMI) but different waist/hip circumference ratio (WHR). Measurements were performed of the activity of the HPA axis and the sympathetic nervous system, as well as metabolic and endocrine variables.Results: Men with a high WHR, in comparisons with men with a low WHR, had higher insulin, glucose, and triglyceride values in the basal state and higher glucose and insulin after an oral glucose tolerance test. Men with high WHR had elevated diurnal adrenocorticotropic hormone (ACTH) values but similar cortisol values, except lower cortisol values in the morning. Diurnal growth hormone concentrations showed reduced peak size. Stimulation of the HPA axis with corticotropin‐releasing hormone (CRH) and laboratory stress showed no difference in ACTH values between groups, but cortisol values were lower in men with high WHR. In comparison with men with a low WHR, men with a high WHR had elevated pulse pressure and heart rate in the basal state and after challenges by CRH and laboratory stress. They also had increased urinary excretion of catecholamine metabolites.Discussion: These results suggest a mild dysregulation of the HPA axis, occurring with elevated WHR independent of the BMI. The results also indicate a central activation of the sympathetic nervous system, such as in the early phases of hypertension, correlating with insulin resistance.
Racial Differences in Insulin Secretion and Sensitivity in Prepubertal Children: Role of Physical Fitness and Physical Activity
Authors: Ku Ching‐Yi , Gower Barbara A. , Hunter Gary R. , Goran Michael I. 
Published: April 2008

AbstractObjective: To investigate in prepubertal children whether physical fitness and/or physical activity are: 1) associated with insulin secretion and sensitivity and 2) account for racial differences in insulin secretion and sensitivity.Research Methods and Procedures: Subjects included 34 African American and 34 white nondiabetic children aged 5 to 11 years. Data were divided into two sets according to the availability of VO2max and physical activity data. Body composition was measured by dual‐energy X‐ray absorptiometry. Subcutaneous abdominal adipose tissue and intra‐abdominal adipose tissue were examined by computed tomography. Insulin sensitivity (SI) and acute insulin response (AIR) were determined by a frequently sampled intravenous glucose tolerance test. An all‐out, progressive treadmill exercise test was used for measuring VO2max. Physical activity data were collected by questionnaire.Results: African American children had lower SI and higher AIR than white children, after adjusting for total body fat mass. African Americans reported higher levels of physical activity (hours/wk) than whites, but had a lower VO2max. In multiple linear regression analysis, hours/wk of activity and hours/wk of vigorous activity, but not moderate activity, were independently related to SI and AIR after adjusting for race, total body fat mass or fat distribution, and total lean tissue mass. VO2max was not related to AIR, and was inversely related to SI, after adjusting for body composition. Race remained significantly associated with both SI and AIR, even after adjusting for body composition, fat distribution, and hours/wk of activity or hours/wk of vigorous activity.Discussion: In summary, overall physical activity and, especially, vigorous activity were associated with insulin secretion and sensitivity. However, neither physical activity nor VO2max explained the racial difference in insulin secretion (higher in African Americans) and sensitivity (lower in African Americans). Thus, racial (African American to white) differences in aspects of insulin action seem to be due to factors other than body composition, fat distribution, cardiovascular fitness, and amount of physical activity.
Effects of Metformin and Vanadium on Leptin Secretion from Cultured Rat Adipocytes
Authors: Mueller Wendy M. , Stanhope Kimber L. , Gregoire Francine , Evans Joseph L. , Havel Peter J. 
Published: April 2008

AbstractObjective: We have reported that glucose utilization regulates leptin expression and secretion from isolated rat adipocytes. In this study, we employed two antidiabetic agents that act to increase glucose uptake by peripheral tissues, metformin and vanadium, as pharmacological tools to examine the effects of altering glucose utilization on leptin secretion in primary cultures of rat adipocytes.Research Methods and Procedures: Isolated adipocytes (100 μL of packed cells per well) were anchored in a defined matrix of basement membrane components (Matrigel) with media containing 5.5 mM glucose and incubated for 96 hours with metformin or vanadium. Leptin secretion, glucose utilization, and lactate production were assessed.Results: Metformin (0.5 and 1.0 mM) increased glucose uptake in the presence of 0.16 nM insulin by 37 ± 10% (p < 0.005) and 62 ± 8% (p < 0.0001) over insulin alone, respectively. Metformin from 0.5 to 5.0 mM increased lactate production by 105 ± 43% (p < 0.025) to 202 ± 52% (p < 0.0025) and at 1.0 and 5.0 mM increased the proportional rate of glucose conversion to lactate by 78 ± 18% (p < 0.005) and 166 ± 41% (p < 0.0025), respectively. At concentrations less than 0.5 mM, metformin did not affect leptin secretion, but at 0.5 mM, the only concentration that significantly increased glucose utilization without increasing glucose conversion to lactate, leptin secretion was modestly stimulated (by 20 ± 9%; p < 0.05). Concentrations from 1.0 to 25 mM inhibited leptin secretion by 25 ± 8% (p < 0.005) to 89 ± 4% (p < 0.0001). Across metformin doses, leptin secretion was inversely related to the percentage of glucose taken up and released as lactate (r = −0.74; p < 0.0001). Vanadium (5 to 20 μM) increased glucose uptake from 20 ± 7% (p < 0.01) to 34 ± 13% (p < 0.02) and increased lactate production at 5 μM by 17 ± 8% (p < 0.025) and 10 μM by 61 ± 20% (p < 0.02) but did not alter the conversion of glucose to lactate. Vanadium (5 to 50 μM) inhibited leptin secretion by 33 ± 6% (p < 0.0025) to 61 ± 8% (p < 0.0001).Discussion: Both metformin and vanadium increase glucose uptake and inhibit leptin secretion from cultured adipocytes. The inhibition of leptin secretion by metformin is related to an increase in the metabolism of glucose to lactate. The inhibition by vanadium most likely involves direct effects on cellular phosphatases. We hypothesize that the effect of glucose utilization to stimulate leptin production involves the metabolism of glucose to a fate other than anaerobic lactate production, possibly oxidation or lipogenesis.
Asthma and Maternal Body Mass Index Are Related to Pediatric Body Mass Index and Obesity: Results from the Third National Health and Nutrition Examination Survey
Authors: Epstein Leonard H. , Wu Yow‐Wu B. , Paluch Rocco A. , Cerny Frank J. , Dorn Joan P. 
Published: April 2008

AbstractObjective: Clinical research has shown an increased prevalence of obesity in children with asthma. This study was designed to assess the relationship between asthma and pediatric body mass index (BMI) in a national database and to examine factors that may modify this relationship.Design: The cross‐sectional relationship between asthma and pediatric BMI and obesity (BMI ≥ 85th percentile) was studied. Variables that may influence the relationship between asthma and pediatric BMI, such as race/ethnicity and television watching were included in the model for the total sample. A smaller sample of 3009 white and African American youth were studied in regression models including maternal BMI.Study Population: A nationally representative crosssectional sample of 5154 children and adolescents of 6 to 16 years of age from the Third National Health And Nutrition Examination Survey.Results: In the full sample, asthma and television watching were related to BMI, accounting for 3% of the variance in BMI. When maternal BMI was included in the nonHispanic sample, television watching, maternal BMI, and the interaction of maternal BMI and asthma were related to youth BMI, accounting for 15% of the variance. The standardized BMI z‐score for those youth without asthma and no maternal obesity was 0.06, which increased to 0.33 if the youth had asthma, to 0.70 if the youth did not have asthma but the mother was obese, and to 1.71 if the youth had asthma and the mother was obese. Asthma, television watching, and maternal BMI were independent predictors of youth obesity.Conclusions: BMI and prevalence of obesity is higher in youth with asthma. Pediatric BMI, but not obesity, is also related to the interaction of asthma and maternal BMI in white and African American youth. Comorbidity of asthma and obesity may complicate treatment of either condition, and prevention of obesity should be encouraged for asthmatic children.