A comparison of measurements of lean body mass derived by bioelectrical impedance, skinfold thickness and total body potassium. A study in obese and non-obese normal subjects

The measurement of body composition is an important part of metabolic and epidemiological research, but most currently available methods are complex and expensive. We have, therefore, compared measurements of fat mass (FM) and lean body mass (LBM), obtained using a commercially available bioelectrical impedance monitor (The Holtain Body Composition Monitor) (IMP), and by measuring skinfold thickness (SFT), with values obtained by measuring total body potassium (TBK). Twenty subjects, 10 with a body mass index (BMI) less than 30 (kg m-2), (non-obese) and 10 with BMI greater than or equal to 30 (obese) took part in the study. There was a strongly significant linear relationship between LBM calculated from TBK and that calculated from impedance (IMP), in both non-obese and obese groups analysed separately (non-obese: r = 0.92; p less than 0.001 and obese: r = 0.92; p less than 0.001) and together (all: r = 0.89; p less than 0.001). LBM calculated from TBK was strongly linearly correlated with values derived from SFT for non-obese (r = 0.91; p less than 0.001) but not for obese subjects. Mean values of LBM of non-obese subjects derived by each method were not significantly different (TBK: 51.3 +/- 10.40 kg; IMP: 53.18 +/- 10.37 kg; SFT: 48.87 +/- 9.48 kg), but significant differences existed when the subjects were obese (TBK: 51.86 +/- 9.65 kg; IMP: 58.69 +/- 8.55 kg; SFT: 67.61 +/- 8.14 kg; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Longitudinal trends in left ventricular cardiac output in healthy infants in the first year of life

We studied left ventricular (LV) cardiac output as estimated by ascending aorta blood flow (QAo) longitudinally in 31 healthy infants from birth through the first year of life using noninvasive pulsed Doppler ultrasound technique. The temporal mean ascending aortic blood flow velocity (VAo) was measured with a 5-MHz pulsed Doppler velocimeter and on line integration system. Ascending aortic cross-sectional area (AAo) was determined using M-mode echography. Ascending aortic blood flow was calculated as QAo = VAo X AAo and was corrected to body weight (BW) in kilograms or body surface area (BSA) in meters squared. Mean ascending aortic flow velocity (VAo) remained relatively constant over the first year, averaging 20.5 +/- 3.4 cm/sec (+/- SD). Changes in AAo over time correlated strongly with changes in BW or BSA (r = 0.99). Therefore, changes in QAo correlated strongly with changes in AAo, BW, and BSA (r = 0.99). LV cardiac output corrected for body weight or BSA remained relatively constant throughout the first year, mean values ranging from 180-226 ml/min/kg or 3.06-3.76 L/min/m2 and averaging 204 +/- 45 ml/min/kg or 3.48 +/- 0.74 L/min/m2. A similar strong correlation was seen between serial changes in LV stroke volume and changes in BW or BSA (r = 0.99).     

Sonographic assessment of changes in thickness of different abdominal fat layers in response to diet in obese women

PURPOSE: We evaluated the potential application of sonography to monitor alterations in abdominal fat thickness in obese women before and after dieting. METHODS: This study included 40 obese women (mean age, 42.2 +/- 9.4 years; mean body mass index [BMI], 36.0 +/- 5.9 kg/m2) who underwent a 3-month low-calorie diet. Height, weight, waist circumference (WC), and hip circumference (HC) were measured. BMI and waist-to-hip ratio (WHR) were calculated. Abdominal subcutaneous (S) and intra-abdominal preperitoneal (P) fat were measured at their maximum (max) and minimum (min) thickness sites using a 7.5-MHz linear-array probe. Intra-abdominal visceral (V) fat was measured using a 3.5-MHz convex-array probe. Measurements were taken before and after caloric restriction. RESULTS: The mean weight was reduced from 88.6 +/- 17.1 kg to 83.0 +/- 15.9 kg (p < 0.0001). The mean changes in S(min) (r = 0.376, p = 0.017), S(max) (r = 0.508, (p = 0.001), P(min) (r = 0.439, p = 0.005), and V (r = 0.365, p = 0.022) fat thicknesses were positively correlated with change in weight; the change in P(max) fat thickness showed the best and most significant correlation (r = 0.591, p < 0.0001). BMI (r = 0.969, p < 0.0001), WC (r = 0.510, p = 0.001), and HC (r = 0.422, p = 0.007) changes were also positively correlated with weight change, but the WHR change (r = 0.019, p > 0.05) was not. CONCLUSIONS: All the abdominal fat layers, particularly the intra-abdominal P fat, will decrease in response to loss of body fat by dieting. Sonography seems to be useful in monitoring small variations in the thicknesses of abdominal S and intra-abdominal P and V fat.     

Association between regional adipose tissue distribution and both type 2 diabetes and impaired glucose tolerance in elderly men and women

OBJECTIVE: We examined whether regional adipose tissue distribution, specifically that of skeletal muscle fat and visceral abdominal fat aggregation, is characteristic of elderly individuals with hyperinsulinemia, type 2 diabetes, and impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS: A total of 2,964 elderly men and women (mean age 73.6 years) were recruited for cross-sectional comparisons of diabetes or glucose tolerance, generalized obesity with dual-energy X-ray absorptiometry, and regional body fat distribution with computed tomography. RESULTS-Approximately one-third of men with type 2 diabetes and less than half of women with type 2 diabetes were obese (BMI > or =30 kg/m(2)). Despite similar amounts of subcutaneous thigh fat, intermuscular fat was higher in subjects with type 2 diabetes and IGT than in subjects with normal glucose tolerance (NGT) (11.2 +/- 9.4, 10.3 +/- 5.8, and 9.2 +/- 5.9 cm(2) for men; 12.1 +/- 6.1, 10.9 +/- 6.5, and 9.4 +/- 5.3 cm(2) for women; both P < 0.0001). Visceral abdominal fat was also higher in men and women with type 2 diabetes and IGT than in subjects with NGT (172 +/- 79, 163 +/- 72, and 145 +/- 66 cm(2) for men; 162 +/- 66, 141 +/- 60, and 116 +/- 54 cm(2) for women; both P < 0.0001 across groups). Higher rates of intermuscular fat and visceral abdominal fat were associated with higher fasting insulin in normal-weight (BMI <25 kg/m(2)) men (r = 0.24 for intermuscular fat, r = 0.37 for visceral abdominal fat, both P < 0.0001) and women (r = 0.20 for intermuscular fat, r = 0.40 for visceral abdominal fat, both P < 0.0001). These associations were not found in obese subjects. CONCLUSIONS: Elderly men and women with normal body weight may be at risk for metabolic abnormalities, including type 2 diabetes, if they possess an inordinate amount of muscle fat or visceral abdominal fat.     

Effect of body size and body composition on survival in peritoneal dialysis patients.

BACKGROUND: Using 24-hour urinary creatinine excretion as a measure of muscle mass, we examined whether body composition influences the survival of incident peritoneal dialysis (PD) patients. We hypothesized that patients with high body mass index (BMI) and low muscle mass might be considered to have high levels of body fat. METHODS: Using serum creatinines and creatinine clearances reported on Medical Evidence Form 2728, 24-hour urinary creatinine was calculated in 10 140 incident PD patients with normal (18.5 - 24.9 kg/m2) or high (> or = 25 kg/m2) BMI. Patients were classified as low and normal/high muscle mass groups based on the 25th percentile of 24-hour urinary creatinine (0.64 g/day). RESULTS: In multivariable parametric survival models, compared to the normal BMI-normal/high muscle mass patients, high BMI-normal/high muscle mass patients had lower hazard of all-cause [hazard ratio (HR) 0.90, 95% confidence interval (CI) 0.83 - 0.97] and cardiovascular (HR 0.88, 95% CI 0.79 - 0.97) death; high BMI patients with low muscle mass had higher hazard of all-cause (HR 1.29, 95% CI 1.17 - 1.42) and cardiovascular (HR 1.21, 95% CI 1.06 - 1.39) death. CONCLUSION: Both body size and body composition influence survival of incident PD patients. As incident PD patients with high BMI and normal or high muscle mass have the best survival, PD patients should be encouraged to gain muscle mass rather than fat mass.     

Circulating leptin and body composition in chronic obstructive pulmonary disease

Nutritional depletion and weight loss are two features of chronic obstructive pulmonary disease (COPD), and the association between low body mass index (BMI) and poor prognosis in patients with COPD is a common clinical observation. Mechanisms of weight loss are still unclear in COPD. Excessive energy expenditure partly due to increased work of breathing was shown, but other mechanisms have been searched for. Leptin is a hormone secreted by adipocytes that plays an important role in energy homeostasis and regulates body weight through control of appetite and energy expenditure. The aim of this study was to evaluate the association of circulating leptin levels and measures of body composition in COPD patients. Thirty male COPD outpatients (mean age 66.3 +/- 8.4) and 20 controls (mean age 65.9 +/- 10.8) were included in the study. After standard spirometry and body composition measurements, serum leptin concentration was measured by ELISA assay. COPD patients were grouped according to BMI. Mean BMI was 19.01 +/- 2.26 kg/m2 in group 1 (COPD patients with low BMI), 26.85 +/- 4.51 in group 2 COPD (COPD patients with normal/high BMI) and 27.64 +/- 2.75 kg/m2 in healthy controls (group 3). Mean serum leptin concentration was 1.41 +/- 1.86 ng/ml in group 1, 2.60 +/- 1.38 ng/ml in group 2 and 2.82 +/- 1.46 ng/ml in group 3 (p = 0.002). Leptin correlated to not only BMI but also body weight, waist circumference, triceps and biceps skinfold thickness and body fat percent (p < 0.05 for all). Results of this study suggest that the cause of weight loss is not increased circulating leptin in COPD. Instead, leptin remains regulated in COPD and further decreased in patients with low BMI, probably as a compensatory mechanism to preserve body fat content, which should be evaluated in further studies.     

High body mass index and long duration of intubation increase post-extubation stridor in patients with mechanical ventilation

Approximately 20% of mechanically ventilated patients experience post-extubation stridor (PES) and reintubation, which subsequently may lead to an increased risk of morbidity and mortality. The risk of PES development is significantly higher in obese patients. Low air leakage between the endotracheal tube and the trachea, following cuff deflation, may indicate a higher risk for the development of PES. The aim of this study is to identify the relationship between body mass index (BMI) and PES using the cuff-leak test in patients intubated in the respiratory intensive care unit. A total of 67 consecutive intubations on 56 different ventilated patients were included in this study. The mean age was 63.6 +/- 12.1 years and 84% of the patients were male. PES developed in seven patients (10.4%). The mean cuff-leak volume was 395 +/- 187 ml in non-PES patients and 240 +/- 93 ml in PES patients (p = 0.023). The mean BMI was 36 +/- 13 kg/m2 in PES patients and 24 +/- 7 kg/m2 in non-PES patients (p = 0.046). BMI > 26.5 kg/m2 (OR: 1.2), low cuff-leak volume (< 283 ml) and mechanical ventilation required for more than 5 days (OR: 0.9) were independent variables for PES occurrence. We therefore suggest that non-obese patients, short-term intubated patients and those having a high air leakage around the endotracheal tube could be extubated without much difficulty.     

Efficacy of troglitazone on body fat distribution in type 2 diabetes

OBJECTIVE: The insulin-sensitizing action of troglitazone may be mediated through the activation of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and the promotion of preadipocyte differentiation in adipose tissue on which troglitazone has depot-specific effects. We investigated the relationship between efficacy of the drug and body fat distribution. Changes in body fat distribution were also investigated by long-term administration of the drug. RESEARCH DESIGN AND METHODS: Troglitazone was given at a dose of 400 mg/day to 20 patients with type 2 diabetes whose diet and sulfonylurea therapy produced unsatisfactory glycemic control (HbA(1c) >7.8%) and whose insulin secretory capacity was found to be preserved (postprandial C-peptide >3 ng/ml). HbA(1c) values, serum lipid levels, and body weight were measured monthly Body fat distribution was evaluated in subcutaneous (SC) and visceral fat using a computed tomography scan at umbilical levels before and after troglitazone therapy RESULTS: During the 1-year troglitazone treatment, HbA(1c) was significantly decreased (from 9.2 +/- 0.2 to 7.1 +/- 0.2%, P < 0.01), showing lowest values at 4-6 months, whereas body weight was significantly increased (BMI 24.6 +/- 0.6 to 25.7 +/- 0.6 kg/m2, P < 0.01). Reduction of HbA(1c) (deltaHbA(1c)) from the baseline value during treatment was significantly greater in obese patients (BMI >26 kg/m2) than in nonobese patients (-3.2 +/- 0.4 vs. -2.1 +/- 0.3%, P < 0.05) and was more significant in women than in men (-3.2 +/- 0.2 vs. - 1.4 +/- 0.2%, P < 0.01). The level of deltaHbA(1c) during treatment showed a significant negative correlation with SC fat area (r = -0.742, P < 0.01) but not with visceral fat area. Weight gain during troglitazone treatment resulted in increased accumulation of SC fat without a change in visceral fat area and, consequently. in a significant decrease in the visceral-to-SC fat ratio. CONCLUSIONS: Predominant accumulation of SC fat for the visceral fat tissue was an important predictor of the efficacy of troglitazone therapy in patients with type 2 diabetes. Greater efficacy of troglitazone was observed in women who were characterized by more accumulation of SC adipose tissue than men. Long-term administration of the drug resulted in weight gain with increased accumulation of SC adipose tissue, probably because of the activation of PPAR-gamma in the region.     

Circulating ghrelin levels in obese women: a possible association with hypertension

OBJECTIVE: The orexigenic hormone ghrelin induces weight gain by stimulating food intake. Ghrelin has been shown to modulate sympathetic activity, to exert vasodilative effects and to counterreact with leptin on both food intake and blood pressure. Of these two hormones, ghrelin levels are decreased in obesity, whereas leptin levels are increased. In this cross-sectional study, differences in serum ghrelin and leptin levels were examined in normotensive and hypertensive obese women. MATERIAL AND METHODS: Sixty-one normotensive and hypertensive women were classified according to the body mass indices as follows: (a) 18 healthy subjects with BMI 21.5-27.5 kg/m(2); (b) 22 normotensive subjects with BMI 30-47 kg/m(2); (c) 21 hypertensive obese subjects (BMI 30-48 kg/m(2)) with systolic blood pressure > or =140 mmHg or diastolic blood pressure > or =90 mmHg. Anthropometric measurements including height, weight, BMI, waist and hip circumferences and blood pressure were recorded. The levels of ghrelin and leptin were determined in sera using the commercial ELISA kits. RESULTS: In normotensive obese subjects, ghrelin levels were significantly lower than in controls (0.21+/-0.13 vs 0.60+/-0.3 ng/mL), whereas hypertensive obese women had elevated ghrelin levels (0.64+/-0.36 ng/mL). Ghrelin concentration was decreased despite the presence of hypertension in the patients who had BMIs above 35 kg/m(2). Leptin levels were significantly higher in both normotensive and hypertensive obese groups (19.54+/-11.19 and 21.61+/-12.7 ng/mL, respectively) than in controls (7.61+/-3.3 ng/mL), and were not affected by the presence of hypertension in obese subjects. CONCLUSION: Ghrelin was positively associated with hypertension in obese women and this association was inversely influenced by the increase of BMI.     

Impact of overweight on chronic microvascular complications in type 1 diabetic patients

OBJECTIVE: To investigate a possible association of BMI with retinopathy and neuropathy in type 1 diabetes. Retinopathy and neuropathy may not only be related to glycemic control and diabetes duration but also to blood pressure and BMI. RESEARCH DESIGN AND METHODS: A total of 592 type 1 diabetic patients without nephropathy were studied (M/F: 324/268; age: 41 +/- 12 years; duration: 19 +/- 11 years; HbA(1c) [A1C]: 7.9 +/- 1.1%). Patients were subdivided according to BMI: 168 men and 146 women with BMI <25 kg/m(2), and 156 men and 122 women with BMI > or =25 kg/m(2). Retinopathy was examined by fundoscopy and neuropathy by electromyography. RESULTS: Hypertension (>130/85 mmHg) was present in 40%, retinopathy in 53%, and neuropathy in 43% of patients. Overweight subjects had more retinopathy (63 vs. 45%, P < 0.0001, odds ratio [OR] = 2.1) and neuropathy (49 vs. 38%, P = 0.008, OR = 1.6) than normal-weight patients. Patients with retinopathy were older (45 +/- 12 vs. 37 +/- 11 years, P < 0.0001) and had a longer diabetes duration (25 +/- 10 vs. 12 +/- 8 years, P < 0.0001), a higher A1C (8.0 +/- 1.1 vs. 7.7 +/- 1.1%, P = 0.001), and a higher BMI (25.8 +/- 4.1 vs. 24.7 +/- 4.2 kg/m(2), P = 0.001) than individuals without retinopathy. The same results are found in neuropathy. Logistic regression analysis showed that diabetes duration (beta = 0.15, P < 0.0001), blood pressure (beta = 0.22, P = 0.0047), and A1C (beta = 0.24, P = 0.01), but not BMI, lipid levels, sex, or age, were independent risk factors for retinopathy. Likewise, duration (beta = 0.05, P < 0.0001), age (beta = 0.04, P = 0.0001), A1C (beta = 0.35, P < 0.0001), and sex (beta = 0.74, P = 0.0001) but not BMI, lipid levels, or hypertension were independently associated with neuropathy. Men had more neuropathy than women (50 vs. 34%, P < 0.0001, OR = 1.9). Leptin and adiponectin levels did not differ between individuals with or without microvascular complications. CONCLUSIONS: Retinopathy and neuropathy are more prevalent in overweight (BMI > or =25 kg/m(2)) type 1 diabetic subjects. However, logistic regression analysis showed that diabetes duration and A1C remain the main determinants for retinopathy and neuropathy.     

Relationship of serum leptin with age, body weight, body mass index, and bone mineral density in healthy mainland Chinese women

BACKGROUND: Serum leptin concentration is associated with age, fat and bone mineral density (BMD), and there are ethnic differences in physique and BMD values. The relationship between serum leptin concentration and BMD in Chinese women is presently unknown. We examined the relationship of serum leptin concentration with age, body weight, BMI and BMD in mainland Chinese women. METHODS: Serum leptin concentration in a population of 676 Chinese females, aged 20-80 years (45.4+/-14.8 years, mean+/-S.D.), was measured using an enzyme-linked immunosorbent assay (ELISA). BMD values were measured by dual-energy X-ray absorptiometry (DXA) at a number of sites: the posteroanterior lumbar spine (PA, L1-L4), lateral lumbar spine (Lat, L2-L4), hip (including the femoral neck (FN) and total hip (T-hip)), and forearm (one-third region (RU1/3) and total region (RUT)). The relationship between changes in serum leptin concentration with age, body weight, height, body mass index (BMI) and BMD values at six sites were analyzed using 10 different regression models, and the models giving the best fit were selected. RESULTS: The cubic regression model best described the changes in serum leptin concentration with age (R(2)=0.048, p<0.001) and body weight (R(2)=0.352, p<0.001), while the quadratic regression model was best for serum leptin concentration changes with BMI (R(2)=0.410, p<0.001); serum leptin concentration was not correlated with height. Serum leptin concentration was significantly higher in postmenopausal than premenopausal women (p<0.001). Serum leptin concentration was correlated with Lat BMD (R(2)=0.012, p<0.018), FN BMD (R(2)=0.006, p<0.041) and T-hip BMD (R(2)=0.013, p<0.004) in the whole population. In premenopausal women, leptin was positively associated with BMD except for Lat (R(2)=0.029-0.055, p<0.008); in postmenopausal women, leptin was also positively associated with AP, FN, T-hip BMD (R(2)=0.026-0.042, p<0.007). However, after adjusting for BMI not for body weight, there was no association between serum leptin concentration and age. Meanwhile, after adjustment for age, body weight and BMI, there was no association between serum leptin concentration and BMD values in premenopausal and postmenopausal women. CONCLUSIONS: Age-related changes in serum leptin concentration is dependent on BMI, but not a direct determinant of BMD in Chinese females.     

Relationship between body composition and lung function in elderly men and women

Introduction The purpose of this study was to evaluate the relationship between body composition parameters and lung functions including vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), FEV₁:VC ratio, and FEV₁:FVC ratio in elderly men and women. Methods The study was a cross-sectional evaluation of 99 healthy men and women (aged 60–88 years). Anthropometric and body composition parameters (including fat mass [FM], fat-free mass [FFM] and percentage body fat [%BF]) were evaluated using the skinfold method, and lung function was examined using spirometry. Results Data analysis showed %BF, body FM and body mass index (BMI) of women to be significantly higher than men. Also, their body FFM was significantly less than men (P<0.05). Lung volume (P<0.01) and lung capacity values (P<0.05) (VC, FVC, FEV₁, FEV₁:VC, FEV₁:FVC) of women were significantly less than men. There was a positive significant relationship between the FFM versus FVC and FEV₁ values of women and men. A negative significant relationship was demonstrated between body FM, BMI and FVC of all subjects. Conclusion This investigation showed that women aged between 60 and 88 years had a lower lung capacity compared to men of the same age. Older women were found to have a higher body fat ratio than men, and it was found that increasing %BF and BMI had a negative effect on lung functions in both sexes.     

Brozek two‐compartment model under‐estimates body fat in black female athletes

The purpose of this study was to compare percentage body fat (%BF) values of black female athletes calculated using the Heymsfield four‐compartment (4C), Brozek two‐compartment (2C) and Schutte models. Eleven collegiate athletes underwent total body water (TBW) assessment, hydrostatic weighing (HW) and dual energy X‐ray absorptiometry (DXA). Repeated‐measures ANOVA determined that the 4C model yielded %BF values (16·2 ± 1·5%) that were higher than the Brozek model (13·6 ± 1·7%) but similar to the Schutte model (16·7 ± 1·6%). The fat‐free mass density of the athletes (1·109 ± 0·002 kg l^–1) was significantly higher than the value 1·1 kg l^–1 assumed by the 2C model. We conclude that in lean black female athletes, the Brozek 2C model under‐estimates %BF, and that, if only HW is available, the Schutte model should be used to estimate %BF.     

Effect of body mass index (BMI) on estimation of extracellular volume (ECV) in hemodialysis (HD) patients using segmental and whole body bioimpedance analysis

The aim of the study was to investigate whether body mass index (BMI) influences the estimation of extracellular volume (ECV) in hemodialysis (HD) patients when using segmental bioimpedance analysis (SBIA) compared to wrist-to-ankle bioimpedance analysis (WBIA) during HD with ultrafiltration (UF). Twenty five HD patients (M:F 19:6,) were studied, and further subdivided into two groups of patients, one group with a high BMI (25 kg m-2) and the other with a low BMI (<25 kg m-2). Segmental (arm, trunk, leg) and wrist-to-ankle bioimpedance measurements on each patient were performed using a modified Xitron 4000B system (Xitron Technologies, San Diego, CA). No differences in extracellular resistance (R(E), ohms) between wrist-to-ankle (R(W)) and sum of segments (R(S)) were noted for either the high BMI (489.2+/-82 ohm versus 491.6+/-82 ohm, p=ns) or low BMI groups (560.8+/-77 ohm versus 557.5+/-75 ohm, p=ns). UF volume (UFV, liters) did not differ significantly between the groups (4.0+/-0.9 L versus 3.3+/-1.0 L, p=ns), but change in ECV (DeltaECV) differed not only between methods: WBIA versus SBIA in the high BMI group (2.74+/-1.1 L versus 3.64+/-1.4 L, p<0.001) and in the low BMI group (1.86+/-0.9 L versus 2.91+/-1.0 L, p<0.05) but also between the high and lower BMI groups with WBIA (2.74+/-1.1 L versus 1.86+/-0.9 L, p<0.01). However, there was no significant difference in SBIA between BMI groups. This study suggests that the segmental bioimpedance approach may more accurately reflect changes in ECV during HD with UF than whole body impedance measurements.     

Ventilatory efficiency and rate of perceived exertion in obese and non-obese children performing standardized exercise

Sixty children, in the age span 6-17 years originally divided into two groups, matched by age, sex and height--30 obese subjects [15 girls/15 boys; body mass index (BMI) = 27.4 +/- 4.5 m kg-2; ideal body weight (IBW) range = 122-185%] and 30 controls (BMI = 18.8 +/- 2.7 m kg-2) performed incremental treadmill exercise test. Perceived exertion was assessed by means of Category-Ratio Borg scale. The duration of the exercise for the children in the obesity group was significantly shorter than controls (P = 0.010) but obese children have greater absolute values for oxygen uptake (VO2peak ml min-1 = 1907 +/- 671 versus 1495 +/- 562; P = 0.013) and ventilatory variables (VE, VT), which adjusted for body mass decrease significantly (VO2/kg ml min-1 kg-1 = 29.2 +/- 3.8 versus 33.6 +/- 3.5; P < 0.001). Among the various methods for 'normalizing' absolute values of VO2peak for body size, dividing it by body surface area (BSA) yielded the best results (VO2/BSA ml min-1 m-2 = 43.5 +/- 4.6 versus 44.7 +/- 5.6; P = 0.335). The ventilatory efficiency determined either as a slope of VE versus VCO2 or as a simple ratio at anaerobic threshold did not differ between obese and non-obese children in the incremental and recovery periods of exercise. There was a negative correlation of VE/VCO2 slope with age and anthropometric parameters. Obese children rated perceived exertion significantly higher than controls despite the standard workload (Borg score = 6.2 +/- 1.2 versus 5.2 +/- 1.1; P = 0.001). In conclusion, the absolute metabolic cost of exercise is higher in the obesity group compared with the control subjects. Both groups have similar ventilatory efficiency but an increased awareness of fatigue that furthermore limits their physical capacity.     

Prevalence of insulin resistance and prediction of glucose intolerance and type 2 diabetes mellitus in women with polycystic ovary syndrome.

BACKGROUND: Diabetes mellitus type 2 (DM2) affects 10% of women with polycystic ovary syndrome (PCOS). We evaluated the sensitivity and specificity of clinical and fasting biochemical parameters in screening for impaired glucose tolerance (IGT) and DM2. METHODS: Women with PCOS [n=244, age 27.4+/-7.5 years, body mass index (BMI) 27.5+/-6.9 kg/m(2)] and healthy women (n=57, age 26.8+/-5.8 years, BMI 21.3+/-2.1 kg/m(2)) underwent basal blood sampling and an oral glucose tolerance test (oGTT). RESULTS: Insulin resistance was identified in 40.2% of PCOS women. Impaired fasting glucose (5.6-6.9 mmol/L) was found in 30 subjects (12.3%), but the oGTT revealed IGT in only six of these cases and DM2 in one subject. IGT was found in 23 (9.4%) and DM2 in four (1.6%) of the women with PCOS. The conventional upper limits for total cholesterol, triglycerides, systolic and diastolic blood pressure and fasting glucose revealed low sensitivity for the identification of impaired glucose metabolism. CONCLUSIONS: No single parameter nor any combination of them showed an accuracy sufficient for screening of IGT or DM2 in PCOS patients. All PCOS patients should be screened using an oGTT to identify disturbances in glucose metabolism.     

Glomerular filtration rate and kidney volume in normoalbuminuric non-insulin-dependent diabetics--lack of glomerular hyperfiltration and renal hypertrophy in uncomplicated NIDDM

Glomerular filtration rate (GFR) and kidney volume were evaluated in 18 healthy normoalbuminuric non-insulin-dependent diabetic patients and compared to 12 healthy controls matched for sex, age and body mass index (BMI). The patients (12 males, six females) were 61.6 +/- 3.4 (mean +/- SD) years old, the known diabetes duration was 5 +/- 4.8 years, fasting plasma glucose 8.6 +/- 2.3 mmol/l, urinary albumin excretion rate 7.9 x/divided by 2.0 micrograms/min, BMI 26.8 +/- 2.8 kg/m2 and blood pressure systolic/diastolic 145 +/- 19/82 +/- 7 mmHg. The GFR was measured by the plasma clearance of [51Cr]EDTA, using a single shot procedure. The kidney volume was measured by ultrasonic scanning. The GFR was not increased in diabetics: 100.4 +/- 16.7 ml/min/1.73 m2 as compared to controls: 93.8 +/- 11.4 ml/min/1.73 m2. The kidney volume was similar in the two groups. Diabetics: 231.1 +/- 33.4 ml/1.73 m2. Controls: 236.3 +/- 45.7 ml/1.73 m2. There was a borderline significant correlation between kidney volume and GFR (r = 0.40, p = 0.10) in diabetics. No correlation between glycosylated haemoglobin and GFR was found in diabetics. In contrast to the findings in insulin-dependent diabetes renal hypertrophy and hyperfunction were not characteristic features in this series of non-insulin-dependent diabetics. It is suggested that diabetic glomerulopathy is not always a consequence of long-standing hyperfiltration.     

The influence of diabetes on the relationship between N-terminal pro-B-type natriuretic peptide and body mass index

This study evaluated the influence of diabetes on the relationship between N-terminal pro-B-type natriuretic peptide (NT-proBNP) and body mass index (BMI). Simultaneous NT-proBNP and echocardiographic Doppler examinations were performed in 1117 patients with dyspnoea undergoing cardiac catheterization. Patients were divided into BMI > or =25 kg/m2 (obese), 23-25 kg/m2 (overweight) and <23 kg/m2 (non-obese) groups. In the 803 non-diabetic patients, mean plasma NT-proBNP levels in non-obese, overweight and obese patients showed a significant negative correlation with BMI (862.3 +/- 228.8 pg/ml, 611.5 +/- 149.7 pg/ml, 278.3 +/- 172.5 pg/ml, respectively). In the 314 patients with diabetes, there was no correlation between BMI and NT-proBNP. This study demonstrated that obese patients had reduced concentrations of NT-proBNP compared with non-obese patients, despite having higher left ventricular filling pressures. NT-proBNP was not reduced in obese patients with diabetes. These results suggest that factors other than cardiac status impact on NT-proBNP concentration.     

Vancomycin disposition following intraperitoneal administration in children receiving peritoneal dialysis.

BACKGROUND: Little information is available on the disposition of vancomycin during chronic peritoneal dialysis (PD) in children. The primary objective of this study was to investigate the disposition of vancomycin following intraperitoneal (IP) administration in children receiving short-dwell [e.g., automated PD (APD)] and long-dwell [e.g., continuous ambulatory PD (CAPD)] PD. METHODS: A 6-hour exchange containing vancomycin 500 mg/L, using an exchange volume of 1100 mL/m2 body surface area (BSA), was followed by 4-, 6-, and 8-hour antibiotic-free exchanges. The 8-hour exchange was followed by three to four 90-minute antibiotic-free exchanges. Serial blood and dialysis effluent samples were obtained and analyzed for vancomycin concentration by high-pressure liquid chromatography. Pharmacokinetic parameters were computed using noncompartmental methods. RESULTS: The bioavailability of vancomycin during a 6-hour IP exchange was 70% +/- 5%, resulting in a delivered dose of 12.0 +/- 1.8 mg/kg, and a 6-hour serum vancomycin concentration of 23.3 +/- 7.2 microg/mL. Total body vancomycin clearance measured 10.72 +/- 4.52 mL/minute/1.73 m2 BSA, while clearance attributable to PD measured 2.78 +/- 1.08 mL/min/1.73 m2 BSA and accounted for 29% +/- 11% of total vancomycin clearance. Dialysis clearance during long-dwell (CAPD) and short-dwell (APD) regimens was similar, measuring 2.46 +/- 1.04 and 3.09 +/- 1.28 mL/min/1.73 m2 BSA, accounting for 25% +/- 13% and 32% +/- 12% of total body clearance respectively. CONCLUSIONS: Intraperitoneal absorption and dialysis clearance of vancomycin in children receiving PD are similar to those reported in adult dialysis patients. In contrast, total body clearance of vancomycin appears to be increased and the elimination half-life decreased in children, due to increased elimination by non-renal nondialysis routes. For intermittent IP vancomycin therapy in children with peritonitis, an IP load containing vancomycin 1000 mg/L (or 30 mg/kg), followed a single full-fill (1100 mL/m2 BSA) daily exchange, containing vancomycin 250 mg/L (or 7.5 mg/kg), from day 2 until the end of treatment will maintain a vancomycin dialysate concentration of >4 microg/mL.     

Improvement of BMI,body composition,and body fat distribution with lifestyle modification in Japanese Americans with impaired glucose tolerance

OBJECTIVE: To determine whether diet and endurance exercise improved adiposity-related measurements in Japanese Americans with impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS: This study compared the effects of an American Heart Association (AHA) step 2 diet (<30% of total calories as fat, <7% saturated fat, 55% carbohydrate, and < 200 mg cholesterol daily) plus endurance exercise for 1 h three times a week (treatment group) with an AHA step 1 diet (30% of total calories as fat, 10% saturated fat, 50% carbohydrate, and <300 mg cholesterol) plus stretching exercise three times a week (control group) on BMI, body composition (% fat), and body fat distribution at 6 and 24 months of follow-up in 64 Japanese American men and women with IGT, 58 of whom completed the study. RESULTS: At 6 months, the treatment group showed significantly greater reduction in percent, body fat (-1.4 +/- 0.4 vs. -0.3 +/- 0.3%); BMI (-1.1 +/- 0.2 vs. -0.4 +/- 0.1 kg/m(2)); subcutaneous fat by computed tomography at the abdomen (-29.3 +/- 4.2 vs. -5.7 +/- 5.9 cm(2)), thigh (-13.2 +/- 3.6 vs. -3.6 +/- 3.0 cm(2)), and thorax (-19.6 +/- 3.6 vs. -8.9 +/- 2.6 cm(2)); and skinfold thickness at the bicep (-2.0 +/- 0.6 vs. 1.1 +/- 0.6 mm) and tricep (-3.7 +/- 0.8 vs. -0.9 +/- 0.6 mm), which continued despite moving to home-based exercise for the last 18 months. CONCLUSIONS: Diet and endurance exercise improved BMI, body composition, and body fat distribution and, thus, may delay or prevent type 2 diabetes in Japanese Americans with IGT.