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Biomedical subjects

F Xavier Pi-Sunyer

Publications and source records attributed to F Xavier Pi-Sunyer.

At least 37 records · Page 2Linked to original sources
PubMed2004

Pathophysiology and long-term management of the metabolic syndrome.

The metabolic syndrome has been characterized by a cluster of abnormalities that include obesity, hyperglycemia, dyslipidemia, and hypertension. Other conditions associated with this syndrome include microalbuminuria, inflammation, a prothrombotic state, and a fatty liver. Together, these abnormalities lead to an environment where the risk of developing both type 2 diabetes and atherosclerotic cardiovascular disease are greatly enhanced. Recognition of this syndrome by practitioners, early treatment, and long-term management are crucial for disease prevention. Successful treatment requires the introduction of lifestyle changes initially and pharmacotherapy subsequently if lifestyle changes are not sufficient.

Adipocytes↗
PubMed2004

Obesity-related leptin regulates Alzheimer's Abeta.

Abeta peptide is the major proteinateous component of the amyloid plaques found in the brains of Alzheimer's disease (AD) patients and is regarded by many as the culprit of the disorder. It is well documented that brain lipids are intricately involved in Abeta-related pathogenic pathways. An important modulator of lipid homeostasis is the pluripotent peptide leptin. Here we demonstrate leptin's ability to modify Abeta levels in vitro and in vivo. Similar to methyl-beta-cyclodextrin, leptin reduces beta-secretase activity in neuronal cells possibly by altering the lipid composition of membrane lipid rafts. This phenotype contrasts treatments with cholesterol and etomoxir, an inhibitor of carnitine-palmitoyl transferase-1. Conversely, inhibitors of acetyl CoA carboxylase and fatty acid synthase mimicked leptin's action. Leptin was also able to increase apoE-dependent Abeta uptake in vitro. Thus, leptin can modulate bidirectional Abeta kinesis, reducing its levels extracellularly. Most strikingly, chronic administration of leptin to AD-transgenic animals reduced the brain Abeta load, underlying its therapeutic potential.

Alzheimer Disease↗
PubMed2004

The epidemiology of central fat distribution in relation to disease.

The effect of fat distribution on disease risk is a subject of great interest. Central fat has been measured anthropometrically, by computed tomography, and by magnetic resonance imaging. Both cross-sectional and longitudinal studies have related central fat to type 2 diabetes mellitus and cardiovascular disease, independent of body mass index. The mechanism may relate to increased lipolysis causing the liver to increase glucose and very low density lipoprotein output, while muscle uses less. This leads to a rise in blood glucose and triglycerides, a drop in HDL cholesterol, and an increase in small, dense LDL particles. There is also an increase in blood pressure and inflammatory markers. Certain populations put on excess fat more centrally than others. These include Asian populations. It is likely that with better differentiation of abdominal fat into visceral and subcutaneous depots, clearer data will accrue on their impact on disease risk.

Abdomen↗
PubMed2004

Improving energy expenditure estimation for physical activity.

PURPOSE: The purpose of this study was to validate the Intelligent Device for Energy Expenditure and Activity (IDEEA) for estimation of energy expenditure during a variety of activities. An additional aim was to improve the accuracy of the estimation of energy expenditure of physical activity based on second-by-second information of type, onset, and duration of activity. METHODS: This study included two tests: a mask calorimetry test with 27 subjects [age = 33.7 +/- 13.8 (mean +/- SD) yr; BMI = 24.8 +/- 4.8 kg x m] and a respiratory chamber calorimetry test with 10 subjects (age = 32.9 +/- 12.4 yr; BMI = 26.1 +/- 5.6 kg x m). In the mask test, the subjects performed activities (sitting, standing, lying down, level treadmill walking, and running at different speeds) for 50-min durations. For the chamber test, subjects lived in the metabolic chamber for 23 h and performed three exercise sessions to compensate for the confined environment. RESULTS: The results showed significant correlations (P < 0.0001) between energy expenditure estimated by IDEEA and energy expenditure measured by the calorimeters with an accuracy >95%. After corrections for the decrease in sleeping metabolic rate, the estimation accuracy for the chamber test was increased by 1-96.2%, whereas the estimation accuracy for nighttime activity was significantly improved by 4-99%. CONCLUSION: IDEEA provides a suitable method for estimating the energy expenditure of physical activity. It provides both instantaneous and cumulative estimates of energy expenditure over a given period.

Adult↗
PubMed2003

Body cell mass: model development and validation at the cellular level of body composition.

Existing models to estimate the metabolically active body cell mass (BCM) component in vivo remain incompletely developed. The classic Moore model is based on an assumed BCM potassium content of 120 mmol/kg. Our objectives were to develop an improved total body potassium (TBK)-independent BCM prediction model on the basis of an earlier model (Cohn SH, Vaswani AN, Yasumura S, Yuen K, and Ellis KJ. J Lab Clin Med 105: 305-311, 1985), to apply this improved model in subjects to explore the sex and age dependence of the TBK/BCM ratio, to develop a new TBK/BCM model on the basis of physiological associations between TBK and total body water (TBW) at the cellular level of body composition, and to fit this new model with available reference data. Subjects were 112 healthy adults who had the following components measured: TBW by 2H2O or 3H2O, extracellular water by NaBr, total body nitrogen by in vivo neutron activation, bone mineral by dual-energy X-ray absorptiometry, and TBK by whole body counting. Human reference data were collected from earlier published reports. The improved Cohn model-derived TBK/BCM ratio was (mean +/- SD) 109.0 +/- 10.9 mmol/kg and was not significantly related to sex and age. A simplified version of the new TBK-TBW model provided a TBK/BCM ratio almost identical (109.1 mmol/kg) to that derived by the improved Cohn model. The TBK-BCM prediction formula derived from the improved and new models [BCM (kg) = 1/109 x TBK (mmol); or BCM = 0.0092 x TBK] gives BCM estimates approximately 11% higher than the classic Moore model (BCM = 0.0083 x TBK) formulated on rough tissue composition estimates. The present analyses provide a physiologically based, improved, and validated TBK-BCM prediction formula that should prove useful in body composition and metabolism research.

Adult↗
PubMed2003

Cholecystokinin and stomach distension combine to reduce food intake in humans.

The aim of this study was to test the hypothesis that gastric distension can enhance the effect of cholecystokinin (CCK) on reduction of food intake in men and women. Eight normal-weight subjects of each gender were tested four times each with either CCK or saline infusion crossed with gastric distension or no distension. Intravenous infusion of a low dose of CCK octapeptide (CCK-8; 112 ng/min for 23 min) combined with a subthreshold gastric distension induced by a water-filled balloon (300 ml) resulted in a significant (means +/- SED: 191 +/- 61 g in men, 209 +/- 61 g in women, and 200 +/- 43 g combined) reduction in intake of a liquid meal compared with saline infusion and unfilled gastric balloon. This combined effect was the result of a large and significant CCK effect when the stomach was distended (CCK vs. saline with distension: 169 +/- 43 g) and a small and insignificant distension effect (distension vs. no distension without CCK: 31 +/- 43 g). The CCK effect alone on intake (CCK vs. saline) without distension was not significant in men (72 +/- 61 g) but was significant in women (121 +/- 61 g). These results are consistent with the hypothesis that CCK's suppression of food intake is enhanced when the stomach is distended.

Adult↗
PubMed2003

Weight loss with self-help compared with a structured commercial program: a randomized trial.

CONTEXT: Although commercial weight loss programs provide treatment to millions of clients, their efficacy has not been evaluated in rigorous long-term trials. OBJECTIVE: To compare weight loss and health benefits achieved and maintained through self-help weight loss vs with a structured commercial program. DESIGN AND SETTING: A 2-year, multicenter randomized clinical trial with clinic visits at 12, 26, 52, 78, and 104 weeks conducted at 6 academic research centers in the United States between January 1998 and January 2001. PARTICIPANTS: Overweight and obese men (n = 65) and women (n = 358) (body mass index, 27-40) aged 18 to 65 years. INTERVENTION: Random assignment to either a self-help program (n = 212) consisting of two 20-minute counseling sessions with a nutritionist and provision of self-help resources or to a commercial weight loss program (n = 211) consisting of a food plan, an activity plan, and a cognitive restructuring behavior modification plan, delivered at weekly meetings. MAIN OUTCOME MEASURES: Weight change was the primary outcome measure. Secondary outcomes included waist circumference, body mass index, blood pressure, serum lipids, glucose, and insulin levels. RESULTS: At 2 years, 150 participants (71%) in the commercial group and 159 (75%) in the self-help group completed the study. In the intent-to-treat analysis, mean (SD) weight loss of participants in the commercial group was greater than in the self-help group at 1 year (-4.3 [6.1] kg vs -1.3 [6.1] kg, respectively; P<.001) and at 2 years (-2.9 [6.5] kg vs -0.2 [6.5] kg, respectively; P<.001). Waist circumference (P =.003) and body mass index (P<.001) decreased more in the commercial group. Changes in blood pressure, lipids, glucose, and insulin levels were related to changes in weight in both groups, but between-group differences in biological parameters were mainly nonsignificant by year 2. CONCLUSION: The structured commercial weight loss program provided modest weight loss but more than self-help over a 2-year period.

Adult↗
PubMed2003

Lack of effect of sucralose on glucose homeostasis in subjects with type 2 diabetes.

OBJECTIVE: To investigate the effect of 3-months' daily administration of high doses of sucralose, a non-nutritive sweetener, on glycemic control in subjects with type 2 diabetes. DESIGN: A multicenter, double-blind, placebo-controlled, randomized study, consisting of a 6-week screening phase, a 13-week test phase, and a 4-week follow-up phase. SUBJECTS/SETTING: Subjects with type 2 diabetes (age range 31 to 70 years) entered the test phase of this study; 128 subjects completed the study. The subjects were recruited from 5 medical centers across the United States and were, on average, obese. INTERVENTION: Subjects were randomly assigned to receive either placebo (cellulose) capsules (n=69) or 667 mg encapsulated sucralose (n=67) daily for the 13-week test phase. All subjects blindly received placebo capsules during the last 4 weeks of the screening phase and for the entire 4-week follow-up phase. MAIN OUTCOME MEASURES: Glycated hemoglobin (HbA1c), fasting plasma glucose, and fasting serum C-peptide were measured approximately every 2 weeks to evaluate blood glucose homeostasis. Data were analyzed by analysis of variance using repeated measures. RESULTS: There were no significant differences between the sucralose and placebo groups in HbA1c, fasting plasma glucose, or fasting serum C-peptide changes from baseline. There were no clinically meaningful differences between the groups in any safety measure. CONCLUSIONS: This study demonstrated that, similar to cellulose, sucralose consumption for 3 months at doses of 7.5 mg/kg/day, which is approximately three times the estimated maximum intake, had no effect on glucose homeostasis in individuals with type 2 diabetes. Additionally, this study showed that sucralose was as well-tolerated by the study subjects as was the placebo.

Administration, Oral↗
PubMed2003

Obesity and type 2 diabetes.

The increasing prevalence of obesity is accompanied by an increasing prevalence of type 2 diabetes. Obesity not only increases the risk of developing type 2 diabetes but also compounds its health risks and complicates its management. The health benefits of weight loss and the efficacy of current weight loss strategies in obese persons with type 2 diabetes are evaluated. In addition, the article reviews the results of lifestyle intervention trials designed to reduce conversion to type 2 diabetes in at-risk individuals.

Anti-Obesity Agents↗
PubMed2003

Obesity and endocrine disease.

Several endocrine abnormalities are reported in obesity. Some of these abnormalities are considered as causative factors for the development of obesity, whereas others are considered to be secondary effects of obesity and usually are restored after weight loss. Thyroid hormones usually are normal in obesity, with the exception of T3 which is elevated. Prolactin is normal but prolactin response to different stimuli is blunted. GH is low and GH response to stimuli is blunted. IGF-I levels are normal or elevated. Cortisol, ACTH, and urine free cortisol levels are usually normal; however, a hyperresponsiveness of the HPA axis with increased cortisol and ACTH response to stimulatory tests is observed in centrally obese individuals. Total testosterone and SHBG levels are low, but free testosterone levels are usually normal in obese men. LH and FSH levels usually are normal and estrogens are elevated. Norepinephrine levels are elevated, whereas epinephrine levels are low or normal. Aldosterone levels are elevated but renin activity is usually normal. Parathyroid hormone levels are elevated with normal serum calcium levels and increased urine calcium levels. Monogenic mutations that result in severe obesity have been described in several individuals. Also, several endocrine diseases have obesity as one their clinical manifestations. Hypothyroidism, Cushing's syndrome, GH and testosterone deficiency, polycystic ovarian syndrome, insulinoma, hypothalamic lesions, and genetic syndromes often present with obesity. In most of these conditions, appropriate treatment of the primary disease results in weight loss. In addition, the fat cell has been found to be an endocrine organ that produces several peptides that are bioactive and participate in the regulation of adipocyte function.

Adipose Tissue↗
PubMed2003

Elevated plasma cholecystokinin and appetitive ratings after consumption of a liquid meal in humans.

OBJECTIVE: This study had two objectives. The first was to evaluate the possibility that, in a previous study, a soup preload augmented the reduction of food intake in a test meal induced by an exogenous infusion of cholecystokinin (CCK) because the soup also endogenously released CCK. The second was to compare CCK release by soup between men and women to determine whether the increased satiating effectiveness of soup in women as opposed to men could have been partly attributable to differences in CCK release. METHODS: By using a bioassay that measures all of its known isoforms, we determined plasma CCK levels at baseline and at several times postprandially in eight healthy, non-obese men and women (four of each sex). Each subject ingested 800 g of tomato soup, which was followed 30 min later by 300 g of a yogurt shake. Appetitive ratings were also collected and related to CCK levels. RESULTS: Ingestion of tomato soup significantly increased plasma CCK levels by 3.81 pmol/L (+/- 1.21 standard error, P = 0.016) over baseline within 30 min in all subjects combined. When CCK concentrations at 5 min after soup and 5 min after yogurt were averaged, the women's mean averaged concentration was 5.58 pmol/L (+/- 1.994, t = 2.80, P = 0.0073) higher than the men's. The elevated levels persisted but did not rise further upon consumption of the yogurt shake. Hunger ratings declined and fullness ratings increased after eating, although patterns of ratings did not match exactly patterns of CCK release. CONCLUSIONS: A large quantity of tomato soup stimulates significant CCK release; therefore, some of the satiating effects of soup preloads could have been mediated by an elevation in endogenous CCK.

Adolescent↗
PubMed2003

Measurement of human daily physical activity.

OBJECTIVES: To validate a new device, Intelligent Device for Energy Expenditure and Activity (IDEEA), for the measurement of duration, frequency, and intensity of various types of human physical activity (PA). RESEARCH METHODS AND PROCEDURES: The ability of IDEEA to identify and quantify 32 types of PA, including the most common daily exercise and nonexercise PA, was tested in 76 subjects: Subjects included males (N = 33) and females (N = 43) ranging in age from 13 to 72 years with a mean body mass index (BMI) of 24.7 kg/m(2) (range: 18.4 to 41.0) [43 females: 13 to 72 years old and BMI 18.4 to approximately 41.0 kg/m(2) (mean = 24.7 kg/m(2)); 33 males: 15 to approximately 72 years old and BMI 21.0 to approximately 38.4 kg/m(2) (mean = 25.9 kg/m(2))]. Postures, limb movements, and jumping were tested using a timed protocol of specific activities. Walking and running were tested using a 60-meter track, on which subjects walked and ran at 6 self-selected speeds. Stair climbing and descending were tested by timing subjects who climbed and descended a flight of stairs at two different speeds. RESULTS: Correct identification rates averaged 98.9% for posture and limb movement type and 98.5% for gait type. Pooled correlation between predicted and actual speeds of walking and running was high (r = 0.986, p <or= 0.0001). DISCUSSION: IDEEA accurately measured duration, frequency, type, and intensity of a variety of daily PAs.

Adolescent↗
PubMed2003

Is percentage body fat differentially related to body mass index in Hispanic Americans, African Americans, and European Americans?

BACKGROUND: Limited research has been done to explore differences between ethnic groups, including Hispanic Americans (HAs), in the association between percentage body fat (PBF) and body mass index (BMI; in kg/m(2)); the numbers of HAs are increasing in the US population. OBJECTIVE: We investigated whether the relation between PBF and BMI in adult HAs differed from that of African Americans (AAs) and European Americans (EAs). DESIGN: We used a multiple regression model in which PBF measured with dual energy X-ray absorptiometry was predicted by the reciprocal of BMI (1/BMI; in m(2)/kg) in a sample of 487 men (n(EA) = 192, n(AA) = 148, and n(HA) = 147) and 933 women (n(EA) = 448, n(AA) = 304, and n(HA) = 181). RESULTS: For men, our results showed no significant differences between HAs and EAs, AAs and EAs, or HAs and AAs in the slope of the line relating 1/BMI to PBF. In women, there were significant differences in PBF as predicted by BMI between HAs and EAs (P < 0.002) and AAs and HAs (P = 0.020), but not between AAs and EAs. When PBF was estimated on the basis of predicting equations, the trend of the predicted PBF value in women differed according to ethnic group and BMI category. At a BMI < 30, HAs tended to have more body fat than did EAs and AAs, and at a BMI > 35, EAs tended to have more body fat than did the other groups. CONCLUSIONS: Our results show that the relation between PBF and BMI in HA women differs from that of EA and AA women.

Absorptiometry, Photon↗
PubMed2003

Comparisons of waist circumferences measured at 4 sites.

BACKGROUND: Waist circumference (WC) is now accepted as a practical measure of adipose tissue distribution. Four body sites for WC measurements are commonly used, as follows: immediately below the lowest ribs (WC1), the narrowest waist (WC2), the midpoint between the lowest rib and the iliac crest (WC3), and immediately above the iliac crest (WC4). OBJECTIVE: We sought to compare the magnitude and reliability of WC measured at these 4 sites in males and females. DESIGN: WC was measured at each site 1 time in all subjects [49 males and 62 females, aged 7-83 y, with a body mass index (in kg/m(2)) of 9-43] and 3 times in a subgroup (n = 93) by one experienced observer using a heavy-duty inelastic tape. Body fat was measured in a subgroup (n = 74) with the use of dual-energy X-ray absorptiometry. RESULTS: The mean values of WC were WC2 < WC1 < WC3 < WC4 (P < 0.01) in females and WC2 < WC1, WC3, and WC4 (P < 0.01) in males. For all 4 sites, measurement reproducibility was high, with intraclass correlation (r) values > 0.99. WC values were significantly correlated with fatness; correlations with trunk fat were higher than correlations with total body fat in both sexes. CONCLUSIONS: WC values at the 4 commonly used anatomic sites differ in magnitude depending on sex, are highly reproducible, and are correlated with total body and trunk adiposity in a sex-dependent manner. These observations have implications for the use of WC measurements in clinical practice and patient-oriented research.

Abdomen↗
PubMed2003

Depression score predicts weight loss following Roux-en-Y gastric bypass.

BACKGROUND: The prevalence of obesity is increasing in the United States. Bariatric surgery is the only intervention that can reliably induce and maintain significant weight loss in obese patients. The association between pre-surgical severity of depression and success at weight loss following Roux-en-Y gastric bypass (RYGBP) has not yet been fully elucidated. METHODS: 145 charts of patients who underwent RYGBP for morbid obesity were reviewed. 47 patients who filled out the Beck Depression Inventory (BDI) before surgery and completed 1 year of follow-up were studied. The relationship between pre-surgical severity of depression and success at weight loss was examined through multivariate regression analysis using percent excess weight loss (%EWL) as a dependent variable and BDI score as one of the predictors. RESULTS: Weight loss at 1 year was significantly related to the BDI score before surgery (P =0.014). BDI score was also found to be a significant predictor of the amount of weight lost (kg) 1 year after surgery (P =0.027). Age (P =0.03) and initial body mass index (BMI) (P =0.011) were the only other variables with significant independent relations to %EWL. CONCLUSIONS: Our data show a positive correlation between pre-surgical severity of depression as measured by BDI score and the 1-year success at weight loss after RYGBP as measured by %EWL. More depressed individuals tend to lose greater amounts of weight compared with less depressed individuals. Future prospective studies should examine possible mechanisms and effects of depression and other psychiatric disturbances on long-term weight loss after RYGBP.

Adult↗
PubMed2003

Prevalence of co-morbidities in obese patients before bariatric surgery: effect of race.

BACKGROUND: We evaluated the prevalence of co-morbidities, in particular diabetes, in a diverse population of morbidly obese patients who underwent gastric bypass surgery at our institution in New York City. METHODS: A retrospective study of 300 patients who had bariatric surgery between January 2001 and April 2002 was conducted. RESULTS: 57% of the patients had at least one metabolic complication, 30% had diabetes, 38% hypertension and 35% dyslipidemia. Our population was ethnically diverse, with 40% Hispanic, 34% Caucasian, 25% African-American and 1% Asian. There was no difference in the prevalence of diabetes among races. However, Caucasians had the highest prevalence of hyperlipidemia, and the Hispanic patients were the least hypertensive. Among patients with diabetes, one-third were undiagnosed and 50% untreated. Similarly, 45% of the hypertensive patients and 51% of those with hyperlipidemia remained undiagnosed. Men had more co-morbidities than women. CONCLUSION: These results suggest a high prevalence of co-morbid conditions in severely obese patients undergoing bariatric surgery. Age, ethnicity and gender influence the type of co-morbid conditions. More research is needed to understand why diabetes and other metabolic complications remain undiagnosed and untreated in a large number of these high risk patients.

Adolescent↗
PubMed2002

The medical risks of obesity.

Obesity is associated with a number of medical conditions that lead to increased morbidity and increased mortality. Both the National Institutes of Health and the World Health Organization define obesity as a body mass index (BMI) > or = 30 kg/m2 and overweight as a BMI 25-30. The most common conditions associated with obesity are insulin resistance, diabetes mellitus, hypertension, dyslipidemia, cardiovascular disease, gallstones and cholecystitis, sleep apnea and other respiratory dysfunction, and the increased incidence of certain cancers. These are discussed below.

Humans↗