Resting energy expenditure in patients with chronic obstructive pulmonary disease

Resting energy expenditure (REE) was measured in 68 patients with stable chronic obstructive pulmonary disease (COPD) and in 34 weight-stable, age-matched (65 +/- 8 y; means +/- SD) healthy control subjects. Fat-free mass (FFM) determined by bioelectrical resistance explained 84% of the variation in REE in the control group but only 34% in the COPD patients. REE could not reliably be predicted from regression equations either developed in healthy subjects or in COPD patients. REE adjusted for FFM was significantly higher (P less than 0.05) in weight-losing (n = 34) than in weight-stable (n = 34) patients (6851 +/- 781 and 6495 +/- 650 kJ/d, respectively). Pulmonary function was more compromised in weight-losing patients. Adjusted REE in weight-stable patients was significantly higher (P less than 0.01) than in the healthy control group (6131 +/- 405 kJ/d). In patients with COPD, factors in addition to FFM are important determinants of REE. A disease-related increase in REE develops, which may contribute to weight loss in COPD in combination with a lack of an adaptive response to undernutrition in weight-losing patients.     

Skeletal muscle enzymes as predictors of 24-h energy metabolism in reduced-obese persons

BACKGROUND: Little is known about the effects of weight loss on the relation between skeletal muscle enzymes and energy metabolism. OBJECTIVE: This study was performed retrospectively to investigate the relation between skeletal muscle enzymes and 24-h energy metabolism in obese persons before and after weight loss. DESIGN: Ten women and 9 men [with body mass indexes (in kg/m(2)) > 30] underwent a 15-wk weight-loss program (-700 kcal/d). Body weight and composition, 24-h energy metabolism (whole-body indirect calorimetry), and maximal activities of phosphofructokinase (EC 2.7.1.11), creatine kinase (CK; EC 2.7.3.2), citrate synthase (CS; EC 4.1.3.7), 3-hydroxyacyl-CoA dehydrogenase (HADH; EC 1.1.1.35), and cytochrome-c oxidase (COX; EC 1.9.3.1) were determined from biopsy samples of the vastus lateralis taken before and after weight loss. RESULTS: Before weight loss, fat-free mass (FFM) was the only predictor of 24-h energy expenditure (R(2) = 0.70, P < 0.001), whereas the cumulative variance in sleeping metabolic rate explained by FFM and fat mass (FM) was 83% (P < 0.001). After weight loss, CS (r = 0.45, P = 0.05) and COX (r = 0.65, P < 0.01) were significantly associated with 24-h energy expenditure, whereas CK (r = 0.53, P < 0.05), CS (r = 0.45, P < 0.05), COX (r = 0.64, P < 0.01), and HADH (r = 0.45, P = 0.05) were all significant correlates of sleeping metabolic rate. After weight loss, FFM, FM, and COX explained 84% (P < 0.01) of the variance in 24-h energy expenditure, whereas FFM, FM, and CK all contributed to the cumulative variance in sleeping metabolic rate explained by this model (R(2) = 0.82, P < 0.05). CONCLUSION: Maximal activities of key skeletal muscle enzymes contribute to the variability in 24-h energy metabolism in reduced-obese persons.     

慢性阻塞性肺病患者的人体组成

目的应用生物电阻抗分析法,检测慢性阻塞性肺病(COPD)患者的人体组成的改变。方法选择符合COPD诊断标准的37例住院患者作为研究对象,其中男性27例,女性10例,平均年龄(66.7±9.9)岁。49名健康志愿者作为对照,其中男性28名,女性21名,平均年龄为(64.3±8.3)岁。用生物电阻抗法测定人体组成。结果COPD患者的体重较健康志愿者显著降低(P<0.05),其中去脂体质(FFM)降低更加显著(P<0.01),脂肪含量(Fat%)相对增加(P<0.01);总体水(TBW)和TBW/体重明显低于健康志愿者(P<0.05),而女性患者TBW/FFM高于健康志愿者(P<0.05);男性患者的基础代谢率较健康志愿者显著降低(P<0.05)。结论COPD患者存在不同程度的瘦体质消耗增加,脂肪含量相对增加,造成机体总体水含量减少,基础代谢率降低。     

Body composition by bioelectrical-impedance analysis compared with deuterium dilution and skinfold anthropometry in patients with chronic obstructive pulmonary disease

Body composition is an important measure of nutritional status in patients with chronic obstructive pulmonary disease (COPD). We generated a regression model for bioelectrical impedance (BI) by using deuterium dilution (2H2O) as a reference method in 32 COPD patients, aged 63 +/- 9 y (mean +/- SD), in stable pulmonary and cardiac condition. Height squared divided by resistance (Ht2/Res) correlated well with total body water (TBW) as measured by 2H2O (r = 0.93, P less than 0.001, SEE = 1.9 L). The best-fitting regression equation to predict TBW comprised Ht2/Res and body weight (r2 = 0.89, SEE = 1.8 L, P less than 0.001). BI-predicted TBW was used to estimate BI-fat-free mass (FFM) that was compared with skinfold-thickness-based FFM predictions (Anthr-FFM). Relative to BI-FFM a significant overestimation of 4.4 +/- 0.8 kg was found by Anthr-FFM. Our results suggest that BI is a useful measure of body composition in patients with severe COPD.     

Increased fat accumulation in liver may link insulin resistance with subcutaneous abdominal adipocyte enlargement, visceral adiposity, and hypoadiponectinemia in obese individuals

BACKGROUND: Enlargement of adipocytes from subcutaneous abdominal adipose tissue (SAT), increased intrahepatic lipid content (IHL), intramyocellular lipid content (IMCL), and low circulating adiponectin concentrations are associated with insulin resistance. OBJECTIVE: Because adiponectin increases fat oxidation in skeletal muscle and liver, and the expression of the adiponectin gene in SAT is inversely associated with adipocyte size, we hypothesized that hypoadiponectinemia links hypertrophic obesity with insulin resistance via increased IMCL and IHL. DESIGN: Fifty-three obese Pima Indians with a mean (+/-SD) age of 27 +/- 8 y, body fat of 35 +/- 5%, and normal glucose regulation (normal fasting and 2-h glucose concentration per WHO 1999 criteria) underwent euglycemic-hyperinsulinemic clamp, biopsies of SAT and vastus lateralis muscle, and magnetic resonance imaging of the abdomen. RESULTS: Adipocyte diameter (AD) correlated positively with body fat (P < 0.0001) and IHL (estimated from magnetic resonance imaging intensity of liver; P = 0.047). No association was found between AD and plasma adiponectin or IMCL. Plasma adiponectin negatively correlated with type II IMCL (IIA, P = 0.004; IIX, P = 0.009) or IHL (P = 0.02). In a multivariate analysis, plasma adiponectin, AD, and visceral adipose tissue (VAT) independently predicted IHL. Low insulin-mediated glucose disposal was associated with low plasma adiponectin (P = 0.02) and high IHL (P = 0.0003), SAT (P = 0.02), and VAT (P = 0.04). High IHL was the only predictor of reduced insulin-mediated suppression of hepatic glucose production (P = 0.02) and the only independent predictor of insulin-mediated glucose disposal in a multivariate analysis. CONCLUSIONS: Increased lipid content in the liver may independently link hypoadiponectinemia, hypertrophic obesity, and increased visceral adiposity with peripheral and hepatic insulin resistance.     

Factors contributing to alterations in skeletal muscle and plasma amino acid profiles in patients with chronic obstructive pulmonary disease

BACKGROUND: There is increasing evidence of abnormal protein metabolism in patients with chronic obstructive pulmonary disease (COPD), as reflected by lower plasma branched-chain amino acid (BCAA) concentrations and different muscle amino acid (AA) patterns than in age-matched control subjects. OBJECTIVE: We examined whether the low plasma BCAA concentrations in COPD reflect an imbalance between anabolic and catabolic processes as evidenced by a low fat-free mass (FFM) and alterations in the anabolic hormone insulin and whether discrepancies in muscle AA concentrations between studies are related to different patient characteristics. DESIGN: AA profiles in arterial plasma and quadriceps femoris muscle and insulin concentrations in venous plasma were analyzed in 28 postabsorptive COPD patients (14 with and 14 without macroscopic emphysema) and in 28 control subjects. FFM was measured by dual-energy X-ray absorptiometry. RESULTS: The lower sum of plasma BCAAs in the COPD group than in the control subjects was the result of a lower leucine concentration (P: < 0.001); no significant difference in valine and isoleucine was found between the groups. In the COPD group, the lower leucine concentrations were associated with low FFM (P: < 0.01). Compared with the control group, the muscle-to-plasma leucine gradient was higher in the COPD group (P: < 0.001) and was associated with a higher insulin concentration (P: < 0.01). Several muscle AA concentrations were higher or tended to be higher in the group without emphysema than in the control group, whereas nearly all AA concentrations were lower in the group with emphysema. CONCLUSIONS: Leucine metabolism is altered in COPD patients and is associated with low FFM and high insulin concentrations. There were striking differences in the skeletal muscle AA profile between the COPD subtypes.     

Comparison of total body potassium with other techniques for measuring lean body mass in men and women with AIDS wasting

BACKGROUND: Lean body mass is an important predictor of survival and functional status in patients with AIDS wasting. The bias between different techniques for assessing body composition in AIDS wasting is not known. DESIGN: We compared total body potassium (TBK) with fat-free mass (FFM) determined by dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA), and skinfold-thickness measurement (SKF) in 132 patients (63 men, 69 women) with AIDS wasting (weight < 90% of ideal body weight, or weight loss > 10% of original, or both). None of the subjects exhibited clinical lipodystrophy. Comparisons were made by using different BIA equations. RESULTS: Lean body mass determined by DXA was highly correlated with TBK in men (r = 0.79, P: < 0.0001) and women (r = 0.84, P: < 0.0001). FFM(BIA) and FFM(DXA) were significantly different (P: < 0.01 in men and P: < 0.0001 in women). The difference between FFM(DXA) and FFM(BIA) was significantly greater with greater weight and body fat, particularly in HIV-infected women (r = -0.39, P: = 0.001 for weight; r = -0.60, P: < 0.0001 for fat). The comparability of FFM and fat mass determined by DXA and BIA was dependent on the specific BIA equation used. Among men, no single BIA equation was more highly predictive of fat mass and FFM in comparison with DXA. CONCLUSIONS: The differences between DXA, BIA, and SKF in the determination of fat mass and FFM are significant in patients with AIDS wasting. BIA overestimates FFM compared with DXA in those with greater body fat. Standard BIA equations may not accurately estimate FFM and fat mass in men and women with AIDS wasting.     

Skeletal muscle weakness is associated with wasting of extremity fat-free mass but not with airflow obstruction in patients with chronic obstructive pulmonary disease

BACKGROUND: Skeletal muscle weakness is a prominent problem in many patients with chronic obstructive pulmonary disease (COPD). OBJECTIVE: The aim of the study was to determine the relation between skeletal muscle function, body composition, and lung function in COPD (emphysema and chronic bronchitis) patients and healthy volunteers. DESIGN: In 50 patients with chronic bronchitis, 49 patients with emphysema, and 28 healthy volunteers, skeletal muscle function was assessed by handgrip and linear isokinetic dynamometry. Whole-body and subregional fat-free mass (FFM) were assessed by dual-energy X-ray absorptiometry. RESULTS: Whole-body and extremity FFM were significantly lower in patients with emphysema (P < 0.001) and chronic bronchitis (P < 0.05) than in healthy volunteers, but trunk FFM was significantly lower only in patients with emphysema (P < 0.001). Extremity FFM was not significantly different between the COPD subtype groups, despite significantly lower values for whole-body and trunk FFM (P < 0.05) in patients with emphysema. Absolute skeletal muscle function (P < 0. 001) and muscle function per kilogram of whole-body FFM were significantly lower in both COPD subtype groups than in healthy volunteers (P < 0.05), but no significant difference was found between patients with chronic bronchitis and those with emphysema. Muscle function per kilogram of extremity FFM was not significantly different between the 3 groups and was not associated with forced expiratory volume in 1 s. CONCLUSION: Skeletal muscle weakness is associated with wasting of extremity FFM in COPD patients, independent of airflow obstruction and COPD subtype.     

Evaluation of peripheral muscle oxygenation during exercise by spatially resolved spectroscopy in patients with chronic obstructive pulmonary disease

BACKGROUND: Spatially resolved (SR) spectroscopy has enabled non-invasive and continuous measurement of muscle oxygen saturation during exercise. In patients with chronic obstructive pulmonary disease (COPD), skeletal muscle dysfunction has been widely studied histochemically and biochemically. However, impairment of muscle oxygenation during exercise has not been elucidated yet. METHODS: We measured oxygen saturation in the vastus lateralis muscle (SmO2) using SR spectrometry during incremental cycle exercise in 16 COPD patients and 10 age-matched healthy subjects. RESULTS: Significant decrease in SmO2 was found at peak exercise compared with warm-up in both groups (56.9 +/- 6.0% to 47.3 +/- 6.8% in patients with COPD, p<0.001; 60.7 +/- 5.8% to 49.9 +/- 7.7% in healthy subjects, p<0.01). The decrease in SmO2 was linear with respect to increase in work rate, and the slope of SmO2 was significantly steeper in COPD patients than in healthy subjects (-0.282 +/- 0.159 vs -0.107 +/- 0.057 %/Watt, p<0.001). The slope of SmO2 in COPD patients significantly correlated with body mass index (BMI) (p<0.01), peak percutaneous oxygen saturation (p<0.05), and peak pulmonary oxygen consumption (p<0.05). Stepwise regression analysis revealed that BMI was a significant determinant of the SmO2 slope (p=0.01). CONCLUSIONS: We conclude that oxygenation of peripheral muscle is impaired during exercise in COPD patients and that BMI contributes independently to the change of muscle oxygen saturation with exercise in COPD patients. SR spectroscopy will provide useful information for the study of the dynamics of muscle oxygenation in COPD patients.     

Nutrition status in patients younger and older than 60 y at hospital admission: a controlled population study in 995 subjects

OBJECTIVE: Body weight and body mass index are easily obtainable indicators of nutrition status but do not provide information on changes in fat-free mass (FFM) and fat mass with age. In this prospective controlled study, we investigated whether body composition measurements were useful in identifying moderately or severely depleted patients, as judged by the Subjective Global Assessment at hospital admission. In addition, the subjects were grouped by age (< or =60 and >60 y) to determine whether there was an effect of aging on the prevalence of malnutrition.METHODS: Nine hundred ninety-five consecutive patients were evaluated for malnutrition by body mass index, serum albumin, Subjective Global Assessment, and 50-kHz bioelectrical impedance analysis and compared with 995 age- and height-matched healthy volunteers for FFM and fat mass. RESULTS: A body mass index less than 20 kg/m(2) was found in 17.3% of patients. Low albumin (< or =34.9 g/L) was found in 14.9% of all patients and 23.7% of those older than 60 y. In contrast, 23.1% and 38.3% of all patients were severely and moderately depleted, respectively, according to the Subjective Global Assessment. FFM was significantly lower in severely depleted men and women and moderately depleted women (P < or = 0.001), and fat mass was significantly higher (P < or = 0.05) in well-nourished patients than in volunteers. Patients older than 60 y had lower FFM and higher fat mass than did patients 60 y or younger or volunteers (P < or = 0.001). CONCLUSION: The prevalence of malnutrition was greater in patients older than 60 y than in those 60 y and younger. Patients classified as severely depleted according to the Subjective Global Assessment were depleted of FFM. Body composition measurement can help to identify patients with low FFM and high fat mass.     

Longitudinal study of body composition changes associated with weight change and physical activity

OBJECTIVE: Weight changes result in fat-free mass (FFM) and body fat (BF) changes. This study determined FFM and BF changes after weight gain or loss and whether these changes differ by gender, physical activity, and age. METHODS: Healthy volunteers, recruited between 1991 and 2003, were followed for 1 y (n = 400) or 3 y (n = 305). Active subjects performed >3 h of physical activity of > or =4.0 metabolic equivalents/wk, sedentary subjects performed <3 h/wk. Body weight and body composition by bioelectrical impedance analysis were determined at year 0, 1, or 3. RESULTS: At years 1 and 3, FFM and BF decreased with weight loss and increased with weight gain. BF was more sensitive (P < 0.03) to weight change than FFM. Compared to weight-stable individuals at year 1, weight gains of 1.0-1.9, 2.0-2.9, and > or =3.0 kg changed FFM by -0.04 (P = 0.90), +0.48 (P = 0.15), and +1.39 kg and BF by +1.35, +1.87, and +3.09 kg, respectively (all P < 0.001). Comparable FFM and BF decreases were observed for weight losses (FFM -0.28 kg, P = 0.38; -0.75 kg, P = 0.04; -1.51 kg, P < 0.001; BF -1.01 kg, P < 0.01; -1.55 kg, P = 0.01; -3.13 kg, P < 0.001). These relations were similar across gender and age strata. At year 1, active individuals were less likely to gain BF with weight gain and more likely to lose BF with weight loss than were sedentary individuals, except for weight losses >3 kg. At year 3, the association between body weight and FFM and BF change was similar between active and sedentary individuals. CONCLUSION: Greater weight changes (>3 kg) are necessary for weight change to have a significant effect on FFM than to have an effect on BF.     

Single prediction equation for bioelectrical impedance analysis in adults aged 20--94 years

Existing equations for bioelectrical impedance analysis (BIA) are of limited use when subjects age or become overweight because these equations were developed in young, normal-weight subjects and are not valid in elderly or overweight people. The purpose of this study was to validate a single BIA equation in healthy white subjects aged 22--94 y with a body mass index between 17.0 and 33.8 kg/m(2). Healthy subjects (202 men and 141 women) aged 20--94 y were measured by two methods: fat-free mass (FFM) was measured by dual-energy x-ray absorptiometry (Hologic QDR-4500) and by a bioelectrical impedance analyzer (Xitron 4000B). Validity of BIA was assessed by double cross validation. Because correlations were high (r = 0.986--0.987) and prediction errors low, a single equation was developed using all subjects, as follows: FFM = -4.104 + (0.518 x height(2)/resistance) + (0.231 x weight) + (0.130 x reactance) + (4.229 x sex: men = 1, women = 0). FFM predicted with dual-energy x-ray absorptiometry was 54.0 +/- 10.7 kg. BIA-predicted FFM was 54.0 +/- 10.5 kg (r = 0.986, standard error of the estimate = 1.72 kg, technical error = 1.74 kg). In conclusion, the new Geneva BIA equation was valid for prediction of FFM in healthy adults aged 22--94 y with body mass indexes between 17.0 and 33.8 kg/m(2). Inclusion of reactance in the single prediction equation appeared to be essential for use of BIA equations in populations with large variations in age or body mass.     

Cellular responses in skeletal muscle to a season of ice hockey

We hypothesized that a season of ice hockey would result in extensive remodeling of muscle. Tissue sampled from the vastus lateralis of 15 players (age = 20.6 ± 0.4 years; mean ± SE) prior to (PRE) and following (POST) a season was used to characterize specific adaptations. Measurement of representative metabolic pathway enzymes indicated higher maximal activities in POST than in PRE (p < 0.05) for succinic dehydrogenase (3.26 ± 0.31 vs. 3.91 ± 0.11 mol mg protein(-1) min(-1)), citrate synthase (7.26 ± 0.70 vs. 8.70 ± 0.55 mol mg protein(-1) min(-1)), and phosphofructokinase (12.8 ± 1.3 vs. 14.4 ± 0.96 mol mg protein(-1) min(-1)) only. The season resulted in an increase in Na+-K+-ATPase concentration (253 ± 6.3 vs. 265 ± 6.0 pmol g(-1) wet weight), a decrease (p < 0.05) in maximal activity of the sarcoplasmic reticulum Ca2+-ATPase (107 ± 4.2 micromol g protein(-1) min(-1) vs. 92.0 ± 4.6 micromol g protein(-1) min(-1)), and no change in the distribution (%) of fibre types. A smaller (p < 0.05) cross-sectional area (CSA) for both type I (-11.7%) and type IIA (-18.2%) fibres and a higher (p < 0.05) capillary count/CSA for type I (+17.9%) and type IIA (+17.2%) were also found over the season. No changes were found in peak oxygen consumption (51.4 ± 1.2 mL kg(-1) min(-1) vs. 52.3 ± 1.3 mL kg(-1) min(-1)). The results suggest, based on the alterations in oxidative and perfusion potentials and muscle mass, that the dominant adaptations are in support of oxidative metabolism, which occurs at the expense of fibre CSA and possibly force-generating potential.     

Body composition in patients with chronic obstructive pulmonary disease: which method to use in clinical practice?

The objective of the present study was to compare anthropometry with bioelectrical impedance (BIA) in relation to densitometry (dual-energy X-ray absorptiometry; DEXA) as methods of nutritional assessment and body composition in out-patients with chronic pulmonary obstructive disease (COPD). We conducted a cross-sectional clinical study with sixty-one patients with COPD (forty-two men and nineteen women), mean age of 66.5 (sd 7.9) years and forced expiratory volume in 1 s of 1.3 (sd 0.6) litres (52.2 (sd 19.8) % predicted), referred to the Pulmonary Rehabilitation Center. The patients were evaluated regarding nutrition status and body composition as determined by anthropometry, BIA and DEXA. In the results, 34.4 % showed mild obstruction, 31.2 %, moderate and 34.4 %, severe obstruction. According to the BMI (mean 24.5 (sd 4.5) kg/m2), 45.9 % of the patients exhibited normal weight, while 27.9 % were underweight and 26.2 % were obese. Related to fat-free mass (FFM), anthropometry and BIA compared with DEXA presented high correlations (r 0.96 and 0.95 respectively; P < 0.001) and high reliability between the methods (alpha 0.98; P < 0.001). Agreement analysis between the methods shows that anthropometry overestimates (0.62 (sd of the difference 2.89) kg) while BIA underestimates FFM (0.61 (sd of the difference 2.82) kg) compared with DEXA. We concluded that according to the nutritional diagnosis, half of our population of patients with COPD showed normal weight, while the other half comprised equal parts obese and underweight patients. Body composition estimated by BIA and anthropometry presented good reliability and correlation with DEXA; the three methods presented satisfactory clinical accuracy despite the great disparity of the limits of agreement.     

Positive energy balance is associated with accelerated muscle atrophy and increased erythrocyte glutathione turnover during 5 wk of bed rest

BACKGROUND: Physical inactivity is often associated with positive energy balance and fat gain. OBJECTIVE: We aimed to assess whether energy intake in excess of requirement activates systemic inflammation and antioxidant defenses and accelerates muscle atrophy induced by inactivity. DESIGN: Nineteen healthy male volunteers were studied before and at the end of 5 wk of bed rest. Subjects were allowed to spontaneously adapt to decreased energy requirement (study A, n = 10) or were provided with an activity-matched diet (study B, n = 9). Groups with higher (HEB) or lower (LEB) energy balance were identified according to median values of inactivity-induced changes in fat mass (DeltaFM, assessed by bioelectrical impedance analysis). RESULTS: In pooled subjects (n = 19; median DeltaFM: 1.4 kg), bed rest-mediated decreases in fat-free mass (bioelectrical impedance analysis) and vastus lateralis thickness (ultrasound imaging) were significantly greater (P < 0.03) in HEB(AB) (-3.8 +/- 0.4 kg and -0.32 +/- 0.04 cm, respectively) than in LEB(AB) (-2.3 +/- 0.5 kg and -0.09 +/- 0.04 cm, respectively) subjects. In study A (median DeltaFM: 1.8 kg), bed rest-mediated increases in plasma leptin, C-reactive protein, and myeloperoxidase were greater (P < 0.04) in HEB(A) than in LEB(A) subjects. Bed rest-mediated changes of glutathione synthesis rate in eythrocytes (l-[3,3-(2)H(2)]cysteine incorporation) were greater (P = 0.03) in HEB(A) (from 70 +/- 19 to 164 +/- 29%/d) than in LEB(A) (from 103 +/- 23 to 84 +/- 27%/d) subjects. CONCLUSIONS: Positive energy balance during inactivity is associated with greater muscle atrophy and with activation of systemic inflammation and of antioxidant defenses. Optimizing caloric intake may be a useful strategy for mitigating muscle loss during period of chronic inactivity.     

Vitamin D receptor genotypes influence quadriceps strength in chronic obstructive pulmonary disease

BACKGROUND: Quadriceps weakness is an important complication of chronic obstructive pulmonary disease (COPD) and is associated with impaired exercise capacity and greater mortality. Its etiology is multifactorial, and evidence is growing that it is partly determined by genetic susceptibility. OBJECTIVE: Using an established cohort, we tested whether quadriceps weakness in patients with COPD is influenced by common variations in the gene for the vitamin D receptor. DESIGN: Vitamin D receptor FokI and BsmI genotypes and the (I/D) angiotensin-converting enzyme (ACE) and bradykinin receptor (+9/-9) genotypes were identified in 107 patients with stable COPD [x +/- SD forced expiratory volume in 1 s (FEV(1)): 34.5 +/- 16.5] and 104 healthy, age-matched control subjects. Quadriceps maximum voluntary contraction force and fat-free mass assessed by bioelectrical impedance analysis were measured. RESULTS: After adjustment for covariables, both patients and control subjects who were homozygous for the C allele of the FokI polymorphism had less quadriceps strength than did those with > or =1 T allele [41.0 +/- 11.8 compared with 46.0 +/- 13.2 kg (P = 0.01) and 32.5 +/- 11.2 compared with 36.2 +/- 13.1 kg (P = 0.005), respectively]. The b allele of the BsmI polymorphism was associated with greater quadriceps strength in patients-37.0 +/- 13.3, 33.8 +/- 11.6, and 33.8 +/- 11.6 kg for bb, bB, and BB, respectively (P = 0.0005)-but had no effect in healthy control subjects. The effect of BsmI on quadriceps strength was least apparent in patients with the ACE II genotype (P = 0.003). CONCLUSIONS: The FokI common variants in the VDR gene are associated with skeletal muscle strength in both patients and control subjects, whereas the BsmI polymorphism is associated with strength only in patients.     

Assessment of fat-free mass using bioelectrical impedance measurements of the human body

A method which involves the measurement of bioelectrical resistive impedance (R) for the estimation of human body composition is described. This method is based upon the principle that the electrical conductivity of the fat-free tissue mass (FFM) is far greater than that of fat. Determinations of R were made in 37 healthy men aged 28.8 +/- 7.1 yr (mean +/- SD) using an electrical impedance plethysmograph with a four electrode arrangement that introduces a painless signal (800 microA at 50 kHz) into the body. FFM was assessed by hydrodensitometry and ranged from 44.6-98.1 kg. Total body water (TBW) determined by D2O dilution and total body potassium (TBK) from whole body counting were 50.6 +/- 10.3 L and 167.5 +/- 38.1 g, respectively. Test-retest correlation coefficient was 0.99 for a single R measurement and the reliability coefficient for a single R measurement over 5 days was 0.99. Linear relationships were found between R values and FFM (r = -0.86), TBW (r = -0.86), and TBK (r = -0.79). Significant (p less than 0.01) increases in the correlation coefficients were observed when the predictor Ht2/R was regressed against FFM (r = 0.98), TBW (r = 0.95), AND TBK (r = 0.96). These data indicate that the bioelectrical impedance technique is a reliable and valid approach for the estimation of human body composition. This method is safe, noninvasive, provides rapid measurements, requires little operator skill and subject cooperation, and is portable. Further validation of this method is recommended in subjects with abnormal body composition.     

Effect of obesity on bioelectrical impedance

The purpose of this study was to validate the use of bioelectrical impedance in assessing human body composition and to explore the use of this technique in obesity. Eighty-seven adults varying widely in body composition (range: 8.8-59.0% body fat) underwent measurement of bioelectrical impedance and underwater weighing (density). Fat-free mass determined from density (FFMd) was compared with FFM estimated from bioelectric impedance according to previously published regression equations. Correlation coefficients were high at all levels of body fat (0.94-0.99) but impedance equations overestimated FFM compared with FFMd in subjects greater than 42% body fat. This effect was greatest in subjects greater than 48% body fat and a regression equation was derived for determination of FFM for these subjects. These data confirm the excellent agreement between body composition determined from bioelectrical impedance and density but suggest that caution should be used in applying existing regression equations to very obese subjects.     

Fat-free mass in chronic illness: comparison of bioelectrical impedance and dual-energy x-ray absorptiometry in 480 chronically ill and healthy subjects.

Assessment of fat-free mass (FFM) and fat mass in ambulatory and hospitalized patients permits optimal adaptation of nutrition support. Recent methods for the determination of FFM are dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA). The purpose of this study was to determine if the BIA-determined FFM as estimated by the formula by Kotler et al. and the Geneva formula could be validated when compared to DXA-determined FFM in subjects with various diagnoses. Body composition was measured by BIA and DXA in 480 subjects including healthy young men and women, elite female runners, and patients with various pathologies (including chronic obstructive and restrictive pulmonary disease patients; cystic fibrosis patients; lung, heart, and liver transplantation patients [both pre- and post-], and hemiplegic and AIDS patients). The present results suggest that BIA is relevant in the clinical assessment of body composition, but BIA formulas appropriate to the subject pool must be used for evaluation of FFM and fat mass. The BIA formula by Kotler et al. is appropriate for healthy subjects and patients with AIDS, cystic fibrosis, and pre- or postliver transplantation. The Geneva formula is more appropriate in pulmonary diseases and hemiplegic subjects with normal weight.     

Tuberculosis, human immunodeficiency virus infection, and malnutrition in Burundi.

In order to compare the nutritional status of tuberculosis (TB) patients who were human immunodeficiency virus (HIV)-seropositive with those who were seronegative, we carried out a cross-sectional anthropometric and biochemical assessment, together with bioelectrical impedance analysis (BIA) of the nutritional status of TB patients hospitalized in the Department of Internal Medicine, Bujumbura University Hospital, Burundi, East Africa. Of the 65 TB patients (33 pulmonary, 6 extrapulmonary, and 26 disseminated TB), 50 (76.9%) were HIV-seropositive (HIV+). When assessed according to anthropometric, BIA, and biochemical variables, HIV+ TB patients had more pronounced malnutrition than HIV- patients. Similar results were obtained when the comparison was restricted to patients with only pulmonary TB: HIV+ patients were more malnourished than HIV- patients. The results according to anthropometric measurements were: weight loss (13.5% of HIV- patients versus 26.4% of HIV+ patients, P = 0.005), body mass index (18.6 versus 15.1, P = 0.003), fat free mass (FFM) (13.9 versus 11.9, P < 0.01), and body fat (BF) (4.55 versus 3.71, P = 0.03) expressed per unit height2. BIA showed that the difference in FFM between HIV- and HIV+ TB pulmonary patients was mostly due to a decrease in body cellular mass. Measurements of albumin, prealbumin, and transferrin showed a marked decrease in all three markers in HIV+ TB pulmonary patients. The nutritional status of HIV+ patients with disseminated versus pulmonary TB was similar. The nutritional status of HIV+ TB patients is far worse than that of HIV- TB patients. In such patients, anthropometry underestimates the degree of malnutrition because it does not account for the water component of FFM. Nutritional status should be assessed and nutritional intervention should be provided in an attempt to improve the prognosis of TB patients, especially those who are infected by HIV.