Search

There is an urgent need to measure the motivation to taste a sweet fluid in order to determine the influence of sweet tastes on the potential choices and consumption of beverages in patients with obesity. Current methods utilize either survey instruments or arbitrary operant tasks. The sipometer enables the participant to utilize an actual ingestive behavioral response to measure motivation during access to beverages on either ad libitum (AL) or progressive time ratio (PR) schedules. We determined the sipometer's responsiveness and reliability as a test of change in motivation for sweet tastes after bariatric surgery. Participants (58 patients and 28 controls, BMI: 18.5–24.9 kg/m2) sham-consumed an aspartame-sweetened (S) and non-sweetened (N) beverage under AL and PR schedules at a pre-surgery/baseline and a 3-month and 24-month visit (patients only). Cumulative pressure (CumPres), a measure of effort, was the sum of the pressures exerted during sipping under each condition. Baseline CumPres for PRS was higher than ALS and ALN in patients (p < 0.03) and higher than PRN in controls (p = 0.009). At 3 months, CumPres did not differ amongst conditions in patients, but CumPres for PRS was higher than all other conditions in controls (p < 0.0005). There were no baseline group differences; however, patients' CumPres for PRS was lower than controls' at 3 months (p = 0.002). Patients' CumPres for PRS decreased non-significantly between the baseline and 3 months but increased at 24 months compared to 3 months (p = 0.025) and was no different from baseline. Controls' CumPres for PRS increased at 3 months (p = 0.0359), but CumPres for all conditions was correlated between visits (p's < 0.038). The sipometer is a reliable and sensitive measure of motivation to consume sweet beverages and may reflect changes in post-operative energy intake. [ABSTRACT FROM AUTHOR]

The high prevalence and costs of type 2 diabetes makes it a rapidly evolving focus of policy action. Health systems, employers, community organizations, and public agencies have increasingly looked to translate the benefits of promising research interventions into innovative policies intended to prevent or control diabetes. Though guided by research, these health policies provide no guarantee of effectiveness and may have opportunity costs or unintended consequences. Natural experiments use pragmatic and available data sources to compare specific policies to other policy alternatives or predictions of what would likely have happened in the absence of any intervention. The Natural Experiments for Translation in Diabetes (NEXT-D) Study is a network of academic, community, industry, and policy partners, collaborating to advance the methods and practice of natural experimental research, with a shared aim of identifying and prioritizing the best policies to prevent and control diabetes. This manuscript describes the NEXT-D Study group's multi-sector natural experiments in areas of diabetes prevention or control as case examples to illustrate the selection, design, analysis, and challenges inherent to natural experimental study approaches to inform development or evaluation of health policies.

Insulin resistance (IR) is typically more severe in obese individuals with type 2 diabetes (T2DM) than in similarly obese non-diabetics but whether there are group differences in body composition and whether such differences contribute to the more severe IR of T2DM is uncertain. DEXA and regional CT imaging were conducted to assess adipose tissue (AT) distribution and fat content in liver and muscle in 67 participants with T2DM (F39/M28, age 60 [+ or -] 7 yr, BMI 34 [+ or -] 3 kg/[m.sup.2]) and in 35 similarly obese, non-DM volunteers (F20/M15, age 55 [+ or -] 8 yr, BMI 33 [+ or -] 2 kg/[m.sup.2]). A biopsy of subcutaneous abdominal AT was done to measure adipocyte size. A glucose clamp was performed at an insulin infusion of 80 mU x [min.sup.-1] x [m.sup.-2]. There was more severe IR in T2DM (6.1 [+ or -] 2.3 vs. 9.9 [+ or -] 3.3 mg x [min.sup.1] x kg [FFM.sup.-1]; p < 0.01). Group comparisons of body composition parameters was performed after adjusting for the effect of age, gender, race, height and total fat mass (FM). T2DM was associated with less leg FM (-1.2 [+ or -] 0.4 kg, P < 0.01), more trunk FM (+1.1 [+ or -] 0.4 kg, P < 0.05), greater hepatic fat (P < 0.05), and more subfascial adipose tissue around skeletal muscle (P < 0.05). There was a significant group x sex interaction for VAT (P < 0.01), with greater VAT in women with T2DM (P < 0.01). Mean adipocyte size (AS) did not significantly differ across groups, and smaller AS was associated with increased leg FM, whereas larger AS was related to more trunk FM (both P < 0.05). Group differences in IR were less after adjusting for group differences in leg FM, trunk FM, and hepatic fat, but these adjustments only partially accounted for the greater severity of IR in T2DM. In summary, T2DM, compared with similarly obese nondiabetic men and women, is associated with less leg FM and greater trunk FM and hepatic fat. doi:10.1152/ajpendo.003934.2006 adipocytes; obesity; body composition; computed tomography

The lipodystrophy syndrome (adipose tissue redistribution and metabolic abnormalities) observed with highly active antiretroviral therapy (HAART) during human immunodeficiency virus (HIV) infection may be related to increased proinflammatory cytokine activity. We measured acute cytokine (TNF-[alpha], IL-6, leptin), glycerol, and lactate secretion from abdominal subcutaneous adipose tissue (SAT), and systemic cytokine levels, in HIV-infected subjects with and without lipodystrophy (HIVL+ and HIVL-, respectively) and healthy non-HIV controls. Lipodystrophy was confirmed and characterized as adipose tissue redistribution in HIVL+ compared with HIVL- and controls, by dual-energy X-ray absorptiometry and by whole body MRI. TNF-[alpha] secretion from abdominal SAT and circulating levels of IL-6, soluble TNF receptors I and II, and insulin were elevated in HIVL+ relative to HIVL- and/or controls, particularly in HIVL+ undergoing HAART. In the HIV-infected group as a whole, IL-6 secretion from abdominal SAT and serum IL-6 were positively associated with visceral fat and were negatively associated with the relative amount of lower limb adipose tissue (P < 0.01). Decreased leptin and increased lactate secretion from abdominal SAT were specifically associated with HAART. In conclusion, increased cytokine secretion from adipose tissue and increased systemic proinflammatory cytokine activity may play a significant role in the adipose tissue remodeling and/or the metabolic abnormalities associated with the HIV-lipodystrophy syndrome in patients undergoing HAART. human immunodeficiency virus; tumor necrosis factor-m; interleukin-6; lactate; glycerol; visceral adipose tissue

The effect of recombinant human growth hormone (rhGH) in the treatment of visceral fat accumulation in HIV infection has been studied. Prospective, open-label 24-week rhGH 6 mg/d trials and 24 weeks of 4 mg every other day were conducted, with a washout period of 12 weeks. It was found that rhGH effectively lowers excess visceral adipose tissue often seen with HIV fat redistribution/lipodystrophy, but that adverse effects were seen.

A study is conducted to develop techniques to linear body measurements of obese people with the use of weight measurements alone. A relationships is established between linear body measurements and weight in the study group, results indicate diameter measurements increase by 0.9-1.1 cm for every 22.04 lbs after 300 lbs, and implications of the study in providing health equipment for obese people are discussed.

Research was conducted to examine the quality of body mass index (BMI) measurements of obese individuals. Data were obtained from a sample of 107 individuals with BMI greater than or equal to 50 kg/sq m whose measurements were taken according to blood sample, height and weight, body fat and sagittal diameter. Results indicate significant and logistic challenges in attempting to derive measurements among massively obese individuals.

In the absence of a ⩒o2-work-rate plateau, debate continues regarding the best way to verify that the peak ⩒o2 achieved during incremental exercise (⩒o2peak) is the "true ⩒o2max." Oft-used "secondary criteria" have been questioned in conjunction with the contention that a severe-intensity constant-work-rate "verification bout" should be considered the "gold standard." The purpose of this study was to compare the ⩒o2peak during ramp incremental cycling (RAMP-INC) by a heterogeneous (with respect to body composition and sex) cohort of sedentary individuals with the ⩒o2peak during severe-intensity constant-work-rate cycling (CWR) performed after RAMP-INC at the highest work rate achieved. A secondary purpose was to determine the degree to which traditional and newly-proposed age-dependent secondary criteria (RER, HR) identified RAMP-INC which CWR confirmed were characterized by a submaximal ⩒o2peak. Thirty-five healthy male (n = 19: 33.4 ± 6.3 yrs) and female (26.8 ± 3.6 yrs) sedentary participants performed RAMP-INC followed by CWR. The ⩒o2peak values from the two tests were correlated (r = 0.96; p < 0.01; mean CV = 24%); however, ⩒o2peak for CWR was significantly greater (29.6 ± 7.2 v. 28.6 ± 6.8 mL∙min-1∙kg-1; p < 0.01) with a mean bias of 0.98 mL∙min-1∙kg-1 (z = -2.9, p < 0.01). Both traditional and newly-proposed criterion values for RER were achieved during RAMP-INC by 33 of 35 participants (including 21 of 23 who registered a higher ⩒o2peak on CWR). The traditional HR criterion value was achieved on only seven tests (three of which were confirmed to be characterized by a submaximal ⩒o2peak) while use of less stringent newly-proposed criteria resulted in acceptance of an additional seven tests of which five were confirmed to be submaximal. Severe-intensity CWR to limit of tolerance indicates that RAMP-INC underestimates ⩒o2max in sedentary individuals and both traditional and newly-proposed secondary criteria are ineffective for identifying such tests. [ABSTRACT FROM AUTHOR]

Impaired insulin action in subcutaneous adipocytes from women with visceral obesity. Am J Physiol Endocrinol Metab 280: E40-E49, 2001.--Visceral obesity is associated with resistance to the antilipolytic effect of insulin in vivo. We investigated whether subcutaneous abdominal and gluteal adipocytes from viscerally obese women exhibit insulin resistance in vitro. Subjects were obese black and white premenopausal nondiabetic women matched for visceral adipose tissue (VAT), total adiposity, and age. Independently of race and adipocyte size, increased VAT was associated with decreased sensitivity to insulin's antilipolytic effect in subcutaneous abdominal and gluteal adipocytes. Absolute lipolytic rates at physiologically relevant concentrations of insulin or the adenosine receptor agonist [N.sup.6]-(phenylisopropyl)adenosine were higher in subjects with the highest vs. lowest VAT area. Independenti[y of cell size, abdominal adipocytes were less sensitive to the antilipolytic effect of insulin than gluteal adipocytes, which may partly explain increased nonesterified fatty acid fluxes in upper vs. lower body obese women. Moreover, increased VAT was associated with decreased responsiveness, but; not decreased sensitivity, to insulin's stimulatory effect on glucose transport in abdominal adipocytes. These data suggest that insulin resistance of subcutaneous abdominal and, to a lesser extent, gluteal adipocytes may contribute to increased systemic lipolysis in both black and white viscerally obese women. abdominal and gluteal adipocytes; lipolysis; glucose transport; adipose tissue

Albu, Jeanine B., Michael Curi, Meredith Shut, Laura Murphy, Dwight E. Matthews, and F. Xavier Pi-Sunyer. Systemic resistance to the antilipolytic effect of insulin in black and white women with visceral obesity. Am. J. Physiol. 277 (Endocrinol. Metab. 40): E551-E560, 1999.--This study was designed to determine the role of visceral adipose tissue (VAT) accumulation in systemic fat metabolism and to compare this in black and white women who differ in their manifestations of upper body obesity. Systemic glycerol and free fatty acid (FFA) turnover rates (rates of appearance, [R.sub.a]) were measured in the basal state and during a pancreatic euglycemic clamp in nondiabetic, premenopausal, obese black and white women with a wide range of VAT accumulation. The slopes of the regression equations predicting basal and insulin-suppressed [R.sub.a]Glycerol and [R.sub.a]FFA from VAT area, age, and fat mass or fat-free mass did not significantly differ between black and white women. VAT area was the best predictor of the %-suppressed [R.sub.a]Glycerol and [R.sub.a]FFA during the pancreatic clamp (partial r = 0.76, P [is less than] 0.0001 and partial r = 0.60, P [is less than] 0.05, respectively). Basal [R.sub.a]Glycerol, but not [R.sub.a]FFA, was lower in black than in white women (P [is less than] 0.05). During the clamp, black women showed greater insulin suppression of [R.sub.a]Glycerol than of [R.sub.a]FFA (P [is less than] 0.0001) and greater insulin suppression of [R.sub.a]Glycerol (P [is less than] 0.05) but similar suppression of [R.sub.a]FFA compared with white women. These differences were independent of age, fat mass, or fat-free mass and were partly explained by a lower VAT in black women. Thus, in both races, VAT accumulation was associated with systemic resistance to the antilipolytic effect of insulin and, in obese black women, systemic lipolysis measured as glycerol turnover rate was more responsive to insulin suppression than were systemic FFA turnover rates. lipolysis; glycerol; free fatty acids; adipose tissue distribution