Influence of Short‐Term Consumption of the Caffeine‐Free,Epigallocatechin‐3‐Gallate Supplement,Teavigo, on Resting Metabolism and the Thermic Effect of Feeding

Green tea is purported to promote weight loss. Resting metabolic rate (RMR) and the thermic effect of feeding (TEF) are significant components of total daily energy expenditure and are partially determined by the sympathetic nervous system via catecholamine‐mediated stimulation of β‐adrenergic receptors. Epigallocatechin‐3‐gallate (EGCG: the most bioactive catechin in green tea) inhibits catechol‐O‐methyltransferase, an enzyme contributing to the degradation of catecholamines. Accordingly, we hypothesized that short‐term consumption of a commercially available EGCG supplement (Teavigo) augments RMR and TEF. On two separate occasions, seven placebo or seven EGCG capsules (135 mg/capsule) were administered to 16 adults (9 males, 7 females, age 25 ± 2 years, BMI 24.6 ± 1.2 kg/m² (mean ± s.e.)). Capsules (three/day) were consumed over 48 h; the final capsule was consumed 2 h prior to visiting the laboratory. Energy expenditure (ventilated hood technique) was determined at rest and for 5 h following ingestion of a liquid meal (caloric content: 40% RMR). Contrary to our hypothesis, RMR was not greater (P = 0.10) following consumption of EGCG (6,740 ± 373 kJ/day) compared with placebo (6,971 ± 352). Similarly, the area under the TEF response curve (Δ energy expenditure) was also unaffected by EGCG (246,808 ± 23,748 vs. 243,270 ± 22,177 kJ; P = 0.88). EGCG had no effect on respiratory exchange ratio at rest (P = 0.29) or throughout the TEF measurement (P = 0.56). In summary, together RMR and TEF may account for up to 85% of total daily energy expenditure; we report that short‐term consumption of a commercially available EGCG supplement did not increase RMR or TEF.     

Comparison of Methods for Achieving 24‐Hour Energy Balance in a Whole‐Room Indirect Calorimeter

Objective: To evaluate and compare methods for achieving 24‐hour energy balance in a whole‐room indirect calorimeter. Research Methods and Procedures: Twenty‐four‐hour energy expenditure (EE) for 34 healthy adults (16 women, 18 men) was measured in a calorimeter during a prestudy day and on a subsequent nonconsecutive assessment day (AD). Several methods for estimating EE on the AD using activity factors or regression equations with data available before the AD [anthropometrics, body composition, resting metabolic rate (RMR), sleeping metabolic rate (SMR) on prestudy day, 24‐hour EE on prestudy day] were compared for predictive accuracy. Results: Use of a 24‐hour calorimeter stay gave the smallest mean absolute error (119 ± 16 kcal/d) and smallest single maximum error (361 kcal/d). However, several other methods were only slightly, and not significantly, less accurate (e.g., mean absolute error = 131 ± 17, 140 ± 20, and 141 ± 22 kcal/d and greatest error = 384, 370, and 593 kcal/d for anthropometric, RMR, and SMR regression equations, respectively). Fat‐free mass alone and SMR with a simple activity factor were seen to be less accurate. Discussion: Our results indicate that there may be some improvement in achieving 24‐hour energy balance in a metabolic chamber by using a preceding 24‐hour calorimeter stay; that only slightly less accurate predictions can be obtained using a combination of anthropometric, body composition, and/or RMR measurements; and that there is little or no advantage in using SMR from a previous overnight calorimeter stay.     

Meta‐Analysis of the Association of the Trp64Arg Polymorphism in the β3 Adrenergic Receptor with Insulin Resistance

Objective: To clarify the possible association between the Trp64Arg polymorphism and insulin resistance (IR). Research Methods and Procedures: Articles evaluating the effect of the Trp64Arg polymorphism on IR were identified on the MEDLINE and PubMed databases from 1995 to February, 2004. After extraction of relevant data, main and subgroup meta‐analyses were performed to assess the differences in IR indices between Trp/Trp and Trp/Arg genotypes. Results: Forty eligible papers containing 56 subgroups were included in this meta‐analysis. Among a total of 12, 805 subjects, 21.9% had Trp64Arg mutation: 20.8%, heterozygotes and 1.1%, homozygotes. Significant associations were found between this mutation and some indices of IR. The weighted mean difference in fasting insulin, 120‐minute insulin level after oral glucose tolerance test, and homeostasis model assessment between Arg64 and Trp64 was 0.23 [95% confidence interval (CI), 0.05 to 0.42] pM, 0.89 (95% CI, 0.30 to 1.48) pM, and 0.55 (95% CI, 0.14 to 0.96), respectively. Subgroup analysis further indicated that this significant association existed only in the Asian population (p < 0.01) and in the obese (p = 0.02) and diabetes subgroups (p = 0.03). Discussion: Numerous studies have been conducted to examine the relationship between the β3‐adrenergic receptor Trp64Arg polymorphism and components of IR syndrome. However, the results have been inconsistent and have led to controversy about whether this polymorphism is associated with these clinical features. The current meta‐analysis demonstrated the moderate effects of the Trp64Arg polymorphism on IR in the Asian population and in obese and diabetic subgroups.     

Association of Cholecystokinin 1 Receptor and β3‐Adrenergic Receptor Polymorphisms with Midlife Weight Gain

We investigated the relationship of polymorphisms in the cholecystokinin 1 receptor [CCK1R; G to T (n‐128), A to G (n‐81)] and the β₃‐adrenergic receptor (β₃‐AR; Trp64Arg) with midlife weight gain. The participants were 1012 Japanese men and women (40 to 59 years of age). Their weight at 18 years old was obtained from a questionnaire. Weight change was defined as the current weight minus the weight at 18 years old. Subjects were grouped into four categories by these genotypes: W/W = noncarriers, W/H = Arg⁶⁴ carriers of the β₃‐AR, H/W = T (n‐128) or G (n‐81) carriers of the CCK1R, H/H = T (n‐128) or G (n‐81) and Arg⁶⁴ carriers. In men, the interaction between the CCK1R and β₃‐AR polymorphisms was significant (two‐way ANOVA, p < 0.05), but neither the CCK1R nor the β₃‐AR was individually associated with weight gain. The H/H group showed a higher possibility of weight gain of 10 kg or more compared with the W/W group in men. The odds ratio for weight gain (≥10 kg) of H/H was 2.54 (95% confidence interval: 1.50 to 4.30) compared with W/W. In women, neither main effect nor interaction was significant. These results suggest that the combination of CCK1R and the β₃‐AR polymorphisms is a contributing factor for midlife weight gain in men.     

Differences in Resting Metabolic Rate between White and African‐American Young Adults

Objective: A reported lower resting metabolic rate (RMR) in African‐American women than in white women could explain the higher prevalence of obesity in the former group. Little information is available on RMR in African‐American men. Research Methods and Procedures: We assessed RMR by indirect calorimetry and body composition by DXA in 395 adults ages 28 to 40 years (100 African‐American men, 95 white men, 94 African‐American women, and 106 white women), recruited from participants in the Coronary Artery Risk Development in Young Adults (CARDIA), Birmingham, Alabama, and Oakland, California, field centers. Results: Using linear models, fat‐free mass, fat mass, visceral fat, and age were significantly related to RMR, but the usual level of physical activity was not. After adjustment for these variables, mean RMR was significantly higher in whites (1665.07 ± 10.78 kcal/d) than in African Americans (1585.05 ± 11.02 kcal/d) by 80 ± 16 kcal/d (p < 0.0001). The ethnic × gender interaction was not significant (p = 0.9512), indicating that the difference in RMR between African‐American and white subjects was similar for men and women. Discussion: RMR is ～5% higher in white than in African‐American participants in CARDIA. The difference was the same for men and women and for lean and obese individuals. The prevalence of obesity is not higher in African‐American men than in white men. Because of these reasons, we believe that RMR differences are unlikely to be a primary explanation for why African‐American women are more prone to obesity than white women.     

Differences in daily energy expenditure in lean and obese women: the role of posture allocation

Objective: A low resting metabolic rate (RMR) is considered a risk factor for weight gain and obesity; however, due to the greater fat‐free mass (FFM) found in obesity, detecting an impairment in RMR is difficult. The purposes of this study were to determine the RMR in lean and obese women controlling for FFM and investigate activity energy expenditure (AEE) and daily activity patterns in the two groups. Methods and Procedures: Twenty healthy, non‐smoking, pre‐menopausal women (10 lean and 10 obese) participated in this 14‐day observational study on free‐living energy balance. RMR was measured by indirect calorimetry; AEE and total energy expenditure (TEE) were calculated using doubly labeled water (DLW), and activity patterns were investigated using monitors. Body composition including FFM and fat mass (FM) was measured by dual energy X‐ray absorptiometry (DXA). Results: RMR was similar in the obese vs. lean women (1601 ± 109 vs. 1505 ± 109 kcal/day, respectively, P = 0.12, adjusting for FFM and FM). Obese women sat 2.5 h more each day (12.7 ± 3.2 h vs. 10.1 ± 2.0 h, P < 0.05), stood 2 h less (2.7 ± 1.0 h vs. 4.7 ± 2.2 h, P = 0.02) and spent half as much time in activity than lean women (2.6 ± 1.5 h vs. 5.4 ± 1.9 h, P = 0.002). Discussion: RMR was not lower in the obese women; however, they were more sedentary and expended less energy in activity than the lean women. If the obese women adopted the activity patterns of the lean women, including a modification of posture allocation, an additional 300 kcal could be expended every day.     

Lower than predicted resting metabolic rate is associated with severely impaired cardiorespiratory fitness in obese individuals

Obese individuals have reduced cardiorespiratory fitness as compared with leaner counterparts. Regular exercise maintains or increases fitness and lean body mass. Lean body mass, in turn, has a direct impact on resting metabolic rate (RMR). Given these relationships, we sought to evaluate the association between RMR and cardiorespiratory fitness in obese individuals. We evaluated 64 obese individuals (78% female) with direct assessment of RMR and cardiorespiratory fitness via breath‐by‐breath measurement of oxygen consumption and carbon dioxide production at rest and during exercise. The mean age and BMI were 47.4 ± 12.2 years and 47.2 ± 9.2 kg/m², respectively. The majority of subjects, 69%, had a measured RMR above that predicted by the Harris‐Benedict equation. Compared with the higher RMR group, those with a lower than predicted RMR had increased BMI, with values of 52.9 vs. 44.7 kg/m², P = 0.001, respectively. Analysis of those demonstrating significant effort during cardiopulmonary exercise testing (peak respiratory exchange ratio ≥1.10) revealed a significantly higher peak oxygen uptake (VO₂ peak) in the higher RMR group (17.3 ± 3.5 ml/min/kg) compared with the lower RMR group (13.6 ± 1.9 ml/min/kg), P = 0.003. In summary, a lower than predicted RMR was associated with a severely reduced VO₂ peak and a higher BMI in this cohort. These data suggest that morbid obesity may be a vicious cycle of increasing BMI, reduced cardiorespiratory fitness, muscle deconditioning, and lower RMR. Collectively, these responses may, over time, exacerbate the imbalance between energy intake and expenditure, resulting in progressive increases in body weight and fat stores.     

The Trp64Arg Polymorphism of the β3‐Adrenergic Receptor Gene Is Not Associated with Training‐Induced Changes in Body Composition: The HERITAGE Family Study

Objective: To investigate the association between the Trp64Arg polymorphism of the β3‐adrenergic receptor gene and changes in body composition in response to endurance training. Research Methods and Procedures: Adult sedentary white and black subjects participating in the HERITAGE Family Study were measured before and after 20 weeks on endurance training for the body mass index, fat mass, percentage of body fat, fat‐free mass, sum of eight skinfolds, and subcutaneous, visceral, and total abdominal fat areas. The association between the Trp64Arg polymorphism and the response phenotypes, computed as the difference between pre‐ and post‐training values, was tested by analysis of covariance separately in men and women. The gene by race interaction term was also tested. Results: No race differences were observed for allelic and genotype frequencies. Training resulted in significant reduction of body fat in both men and women. No association of the Trp64Arg polymorphism was observed with training‐induced changes for any of the body composition phenotypes in both men and women. Discussion: These results suggest that the Trp64Arg polymorphism of the β3‐adrenergic receptor gene is not related to changes in body composition in response to exercise training.     

β‐Amino acids containing peptides and click‐cyclized peptide as β‐turn mimics: a comparative study with ‘conventional’ lactam‐ and disulfide‐bridged hexapeptides

The increasing interest in click chemistry and its use to stabilize turn structures led us to compare the propensity for β‐turn stabilization of different analogs designed as mimics of the β‐turn structure found in tendamistat. The β‐turn conformation of linear β‐amino acid‐containing peptides and triazole‐cyclized analogs were compared to ‘conventional’ lactam‐ and disulfide‐bridged hexapeptide analogs. Their 3D structures and their propensity to fold in β‐turns in solution, and for those not structured in solution in the presence of α‐amylase, were analyzed by NMR spectroscopy and by restrained molecular dynamics with energy minimization. The linear tetrapeptide Ac‐Ser‐Trp‐Arg‐Tyr‐NH₂ and both the amide bond‐cyclized, c[Pro‐Ser‐Trp‐Arg‐Tyr‐D ‐Ala] and the disulfide‐bridged, Ac‐c[Cys‐Ser‐Trp‐Arg‐Tyr‐Cys]‐NH₂ hexapeptides adopt dominantly in solution a β‐turn conformation closely related to the one observed in tendamistat. On the contrary, the β‐amino acid‐containing peptides such as Ac‐(R)‐β³‐hSer‐(S)‐Trp‐(S)‐β³‐hArg‐(S)‐β³‐hTyr‐NH₂, and the triazole cyclic peptide, c[Lys‐Ser‐Trp‐Arg‐Tyr‐βtA]‐NH₂, both specifically designed to mimic this β‐turn, do not adopt stable structures in solution and do not show any characteristics of β‐turn conformation. However, these unstructured peptides specifically interact in the active site of α‐amylase, as shown by TrNOESY and saturation transfer difference NMR experiments performed in the presence of the enzyme, and are displaced by acarbose, a specific α‐amylase inhibitor. Thus, in contrast to amide‐cyclized or disulfide‐bridged hexapeptides, β‐amino acid‐containing peptides and click‐cyclized peptides may not be regarded as β‐turn stabilizers, but can be considered as potential β‐turn inducers. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

Association of lipin 1 gene polymorphisms with measures of energy and glucose metabolism

Objective: To examine the importance of lipin 1 (LPIN1) gene variation in energy and glucose metabolism. Transgenic animal models have shown that lipin, a protein encoded by the LPIN1 gene, promotes fat synthesis and storage in adipose tissue while decreasing energy expenditure and lipid oxidation in skeletal muscle. Lpin1 was identified as the mutated gene in the fatty liver dystrophy mouse, which exhibits lipin deficiency and features of human lipodystrophy. Research Methods and Procedures: We genotyped five LPIN1 polymorphisms and tested for association with resting metabolic rate (RMR), fat oxidation, fasting plasma insulin and glucose concentration, and obesity‐related phenotypes, including BMI, body fat percentage, sum of six skinfolds, and waist circumference in 712 subjects of the Quebec Family Study. Results: The strongest results were generation‐specific. In parents, RMR of the G/G IVS13 + 3333A>G homozygotes was 107 kcal/d higher than in A/A homozygotes and 39 kcal/d higher than in A/G heterozygotes (p = 0.0003). In offspring, carriers of the C allele of the IVS18 + 181C>T variant had significantly higher (p < 0.0003) insulin levels than T/T homozygotes. These associations remained significant after adjusting for multiple testing. Several other associations between body composition measures and the IVS18 + 181C>T variant were significant (p = 0.05 to 0.003), suggesting a strong pattern of relationships. Discussion: These findings support the hypothesis that sequence variation in the LPIN1 gene contributes to variation in RMR and obesity‐related phenotypes potentially in an age‐dependent manner.     

Labor Saved,Calories Lost: The Energetic Impact of Domestic Labor‐saving Devices

Objective: As the prevalence of obesity has increased, so has sedentariness. Progressive sedentariness has been attributed to greater use of labor saving devices, such as washing machines, and less nonexercise walking (e.g., walking to work). However, there is a paucity of data to support this conclusion. In this study, we address the hypothesis that domestic mechanization of daily tasks has resulted in less energy expenditure compared with performing the same tasks manually. Research Methods and Procedures: Energy expenditure was measured in four groups of subjects (122 healthy adult men and women total) from Rochester, Minnesota. Energy expenditure was measured using indirect calorimetry while subjects performed structured tasks such as cleaning dishes and clothes, stair climbing, and work‐associated transportation, and these values were compared with the respective mechanized activity. Results: Energy expenditure was significantly greater and numerically substantial when daily domestic tasks were performed without the aid of machines or equipment (clothes washing: 45 ± 14 vs. 27 ± 9 kcal/d; dish washing: 80 ± 28 vs. 54 ± 19 kcal/d; transportation to work: 83 ± 17 vs. 25 ± 3 kcal/d; stair climbing: 11 ± 7 vs. 3 ± 1 kcal/d; p < 0.05). The combined impact of domestic mechanization was substantial and equaled 111 kcal/d. Discussion: The magnitude of the energetic impact of the mechanized tasks we studied was sufficiently great to contribute to the positive energy balance associated with weight gain. Efforts focused on reversing sedentariness have the potential to impact obesity.     

Effect of calorie restriction on resting metabolic rate and spontaneous physical activity

Objective: It is unclear if resting metabolic rate (RMR) and spontaneous physical activity (SPA) decrease in weight‐reduced non‐obese participants. Additionally, it is unknown if changes in SPA, measured in a respiratory chamber, reflect changes in free‐living physical activity level (PAL). Research Methods and Procedures: Participants (N = 48) were randomized into 4 groups for 6 months: calorie restriction (CR, 25% restriction), CR plus structured exercise (CR+EX, 12.5% restriction plus 12.5% increased energy expenditure via exercise), low‐calorie diet (LCD, 890 kcal/d supplement diet until 15% weight loss, then weight maintenance), and control (weight maintenance). Measurements were collected at baseline, Month 3, and Month 6. Body composition and RMR were measured by DXA and indirect calorimetry, respectively. Two measures of SPA were collected in a respiratory chamber (percent of time active and kcal/d). Free‐living PAL (PAL = total daily energy expenditure by doubly labeled water/RMR) was also measured. Regression equations at baseline were used to adjust RMR for fat‐free mass and SPA (kcal/d) for body weight. Results: Adjusted RMR decreased at Month 3 in the CR group and at Month 6 in the CR+EX and LCD groups. Neither measure of SPA decreased significantly in any group. PAL decreased at Month 3 in the CR and LCD groups, but not in the CR+EX group, who engaged in structured exercise. Changes in SPA in the chamber and free‐living PAL were not related. Discussion: Body weight is defended in non‐obese participants during modest caloric restriction, evidenced by metabolic adaptation of RMR and reduced energy expenditure through physical activity.     

Metabolic Differences in Response to a High-Fat vs. a High-Carbohydrate Diet

Energy expenditure was measured in a group of 7 subjects who received two isocaloric isonitrogenous diets for a period of 9–21 days with a 4–10-day break between diets. Diet 1 was a high-fat diet (83.5 ± 3.6% of total energy). Diet 2 was a high carbohydrate diet (83.1 ± 3.7% of total energy). Resting and postprandial resting metabolic rate were measured by open circuit indirect calorimetry 2–4 times during each metabolic period. Total energy expenditure (TEE) was measured by the doubly labeled water method over an 8–13-day period. The respiratory quotient was measured 2–4 hours after a meal during each metabolic period for the calculation of total energy expenditure by the doubly labeled water method. Levels of total T₃ (TT₃), T₃ uptake, free thyroid index and T₄ were measured at the end of each metabolic period. No significant changes in resting metabolic rate (RMR) were apparent on the two diets (1567 ± 426 kcal/d high-fat diet and 1503 ± 412 kcal/d high-carbohydrate diet n=7, p<0.15). Total energy expenditure measured in 5 subjects was significantly higher during the high-carbohydrate phase of the diet (2443 ± 422 vs. 2078 ± 482 kcal/d p<0.05). Activity estimated from TEE/RMR was greater on the high-carbohydrate diet but only approached statistical significance (p<0.06). Total T₃ was significantly lower and free thyroid index and T₃ uptake were significantly higher at the end of the high fat diet in comparison to the high-carbohydrate diet. These data suggest that individual tolerance to a high-fat diet varies considerably and may significantly lower TEE by changing levels of physical activity. The explanation for changes in thyroid hormone levels independent of changes in metabolic rate remains unclear.     

Chromatographic profiles of tryptophan and kynurenine enantiomers derivatized with (S)‐4‐(3‐isothiocyanatopyrrolidin‐1‐yl)‐7‐(N,N‐dimethylaminosulfonyl)‐2,1,3‐benzoxadiazole using LC–MS/MS on a triazole‐bonded column

d ‐ and l ‐Tryptophan (Trp) and d ‐ and l ‐kynurenine (KYN) were derivatized with a chiral reagent, (S )‐4‐(3‐isothiocyanatopyrrolidin‐1‐yl)‐7‐(N,N‐dimethylaminosulfonyl)‐2,1,3‐benzoxadiazole (DBD‐PyNCS), and were separated enantiomerically by high‐performance liquid chromatography (HPLC) equipped with a triazole‐bonded column (Cosmosil HILIC) using tandem mass spectrometric (MS/MS) detection. Effects of column temperature, salt (HCO₂NH₄) concentration, and pH of the mobile phase in the enantiomeric separation, followed by MS detection of (S )‐DBD‐PyNCS‐d ,l ‐Trp and ‐d ,l ‐KYN, were investigated. The mobile phase consisting of CH₃CN/10 mM ammonium formate in H₂O (pH 5.0) (90/10) with a column temperature of 50–60 °C gave satisfactory resolution (R s) and mass‐spectrometric detection. The enantiomeric separation of d ,l ‐Trp and d ,l ‐KYN produced R s values of 2.22 and 2.13, and separation factors (α) of 1.08 and 1.08, for the Trp and KYN enantiomers, respectively. The proposed LC–MS/MS method provided excellent detection sensitivity of both enantiomers of Trp and KYN (5.1–19 nM).     

MedGem hand-held indirect calorimeter is valid for resting energy expenditure measurement in healthy children

Objective: To assess the validity of a new hand‐held indirect calorimeter [MedGem (MG)] in the determination of resting energy expenditure (REE; kilocalories per day) in children. Research Methods and Procedures: One hundred male (n = 54) and female (n = 46) children (10.6 ± 3.2 years, 43.9 ± 19.0 kg, 146.1 ± 18.8 cm, 19.6 ± 4.9 kg/m²) participated. Children arrived at the University of Oklahoma body composition laboratory between 5:30 am and 6:15 am after an overnight fast. On arrival, subjects voided and remained quietly in the supine position for 15 minutes before testing. REE was measured by indirect calorimetry (in random order), with both the MG (sitting upright) and the criterion Delta Trac II (DT) (supine). Data are reported as the mean ± standard deviation. Results: The mean MG REE (1452 ± 355 kcal/d) was significantly higher than DT REE (1349 ± 296 kcal/d, p < 0.001). Bland‐Altman analysis revealed a mean bias (MG ? DT) of 104 kcal/d, with limits of agreement of ?241 to +449 kcal/d. To examine the difference in subject positioning, an independent sample of 38 subjects performed the MG in its normal position (sitting) and holding the MG in a supine position. REE by the MG in the sitting position (1475 ± 350 kcal/d) was significantly (p < 0.05) higher than the MG in the supine position (1419 ± 286 kcal/d). Discussion: The mean difference in REE between MG and DT was relatively small (103 kcal/d) but significant; however, a portion of this difference may have been related to differences in subject positioning. These preliminary data indicate that the MG shows promise as a valid tool in the assessment of REE in children.     

Characterization and Distribution of a Cloned Rat μ-Opioid Receptor

Abstract: We have cloned and expressed a rat brain cDNA, TS11, that encodes a μ-opioid receptor based on pharmacological, physiological, and anatomical criteria. Membranes were prepared from COS-7 cells transiently expressing TS11 bound [³H]diprenorphine with high affinity (K_D = 0.23 ± 0.04 nM). The rank order potency of drugs competing with [³H]diprenorphine was as follows: levorphanol (K_i = 0.6 ± 0.2 nM) ≈β-endorphin (K_i = 0.7 ± 0.5 nM) ≈ morphine (K_i = 0.8 ± 0.5 nM) ≈ [d -Ala², N-Me-Phe⁴,Gly-ol⁵]-enkephalin (DAMGO; K_i = 1.6 ± 0.5 nM) ? U50,488 (K_i = 910 ± 0.78 nM) > [d -Pen^2,5]-enkephalin (K_i = 3,170 ± 98 nM) > dextrorphan (K_i = 4,100 ± 68 nM). The rank order potencies of these ligands, the stereospecificity of levorphanol, and morphine's subnanomolar K_i are consistent with a μ-opioid binding site. Two additional experiments provided evidence that this opioid-binding site is functionally coupled to G proteins: (a) In COS-7 cells 50 µM 5′-guanylylimidodiphosphate shifted a fraction of receptors with high affinity for DAMGO (IC₅₀ = 3.4 ± 0.5 nM) to a lower-affinity state (IC₅₀ = 89.0 ± 19.0 nM), and (b) exposure of Chinese hamster ovary cells stably expressing the cloned μ-opioid receptor to DAMGO resulted in a dose-dependent, naloxone-sensitive inhibition of forskolin-stimulated cyclic AMP production. The distribution of mRNA corresponding to the μ-opioid receptor encoded by TS11 was determined by in situ hybridization to brain sections prepared from adult female rats. The highest levels of μ-receptor mRNA were detected in the thalamus, medial habenula, and the caudate putamen; however, significant hybridization was also observed in many other brain regions, including the hypothalamus.     

Components of Total Energy Expenditure in Healthy Young Women Are Not Affected after 14 Days of Feeding with Medium-Versus Long-Chain Triglycerides

PAPAMANDJARIS, ANDREA A., MATTHEW D. WHITE, AND PETER J. H. JONES. Components of total energy expenditure in healthy young women are not affected after 14 days of feeding with medium-versus long-chain triglycerides. Obes Res. Objective: To examine the effect of consumption of medium-chain triglycerides (MCT) vs. long-chain triglycerides (LCT) on total energy expenditure (TEE) and its components in young women during the second week of a 2-week feeding period. Research Methods and Procedures: Twelve healthy lean women (age: 22. 7±0. 7 years, body mass index [BMI]: 21. 5±0. 8 kg/m²) were fed weight maintenance diets containing 15% of energy as protein, 45% as carbohydrate, and 40% as fat, 80% of which was treatment fat, for 2 weeks in a randomized cross-over design separated by a 2-week washout period. Dietary fat was composed of triglycerides containing either 26% medium-chain fatty acids (MCFA) and 74% long-chain fatty acids (LCFA), or 2% MCFA and 98% LCFA. Free-living TEE was measured from day 7 to 14 on each dietary treatment using doubly labeled water (DLW). Basal metabolic rate (BMR) and thermic effect of food (TEF) were measured on days 7 and 14 using respiratory gas exchange analysis (RGE) for 30 minutes and 330 minutes, respectively. Activity-induced energy expenditure (AIEE) was derived as the difference between TEE and the sum of BMR and TEF. Results: The average TEE while consuming the MCT diet (2246±98 kcal/day) did not differ from that of the LCT diet (2186±138 kcal/day. BMR was significantly higher on the MCT diet on day 7 (1219±38 kcal/day vs. 1179±42 kcall day), but not on day 14; there was no effect of diet on TEF. There were no differences in BMR, TEF, or AIEE between diets when expressed as percentages of TEE. On average, BMR, TEF, and AIEE represented 54. 6%, 8. 2%, and 37. 2%, respectively, of TEE. Discussion: Results suggest that between day 7 and day 14 feeding of MCT vs. LCT at these levels, TEE is not affected and that increases seen in energy expenditure following MCT feeding may be of short duration. Thus, compensatory mechanisms may exist which blunt the effect of MCT on energy components over the longer term.     

Polymorphism of DNA Repair Gene xrcc1 and Lung Cancer Risk

The current large-scale meta-analysis was performed to reach a reliable conclusion on the association between X-ray repair cross-complementing 1 (xrcc1) rs1799782 and the development of lung cancer. Studies that investigated the association between rs1799782 and lung cancer risk were identified by searching PubMed. We calculated odds ratio (OR) with corresponding 95 % confidence interval (CI) for Trp/Trp vs Arg/Arg, Trp/Trp + Arg/Trp vs Arg/Arg, and Trp/Trp vs Arg/Trp + Arg/Arg contrast models. Combining all 25 studies, we yielded three summary ORs: 1.07 (95 % CI 0.92–1.23) for Trp/Trp vs Arg/Arg, 0.93 (95 % CI 0.87–1.00) for Trp/Trp + Arg/Trp vs Arg/Arg, and 1.08 (95 % CI 0.94–1.25) for Trp/Trp vs Arg/Trp + Arg/Arg, suggesting rs1799782 was not associated with overall risk of lung cancer. Strikingly, a significantly deceased risk was found among Caucasian populations (Trp/Trp + Arg/Trp vs Arg/Arg, OR = 0.86, 95 % CI 0.76–0.97). This study confirms that xrcc1 rs1799782 may lower the risk of lung cancer among Caucasians.     

Association of BMI with the β3‐Adrenergic Receptor Gene Polymorphism in Japanese: Meta‐Analysis

Objective: To assess the effect of the Trp64Arg polymorphism in the β3‐adrenergic receptor gene (ADRB3) on body mass index (BMI) in the Japanese population. Research Methods and Procedures: We selected studies that evaluated the association between BMI and ADRB3 polymorphism among Japanese, using MEDLINE and PubMed. After data collection, an extension of ANOVA was performed to assess the differences according to the genotype. Results: In a total of 35 subgroups including 2316 subjects with the Trp64Arg variant and 4266 subjects without this variant, the weighted mean difference in BMI was 0.26 kg/m² (95% confidence interval: 0.18 to 0.42; p < 0.01), indicating that variant carriers exhibited higher BMI than did normal homozygous subjects. Discussion: Although it is known that the allele frequency of the ADRB3 polymorphism differs among races, this study focuses on the Japanese population, which has a high allele frequency of ADRB3 polymorphism. We assumed that statistical errors would be prevented due to the sufficient number of subjects. In conclusion, the results support the hypothesis that ADRB3 gene polymorphism is associated with BMI.     

Physical activity-related energy expenditure with the RT3 and TriTrac accelerometers in overweight adults

Objective: The objective was to evaluate two accelerometers, the RT3 and the TriTrac‐R3D for their ability to produce estimates of physical activity‐related energy expenditure (PAEE) in overweight/obese adults. Research Methods and Procedures: PAEE estimates from both accelerometers were obtained in two experiments. In Experiment 1, 13 overweight/obese subjects (BMI 34.2 ± 6.4 kg/m²) were monitored over 2 weeks in everyday life, PAEE being simultaneously measured by the doubly labeled water method (DLW). In Experiment 2, 8 overweight/obese subjects (BMI 34.3 ± 5.0 kg/m²) and 10 normal‐weight subjects (BMI 20.8 ± 2.1 kg/m²) were monitored during a treadmill walking protocol, PAEE being simultaneously measured by indirect calorimetry. Results: In Experiment 1, there was no significant difference between methods in mean PAEE (DLW: 704 ± 223 kcal/d, RT3: 656 ± 140 kcal/d, TriTrac‐R3D 624 ± 419 kcal/d). The relative difference between methods (accelerometer vs. DLW) was ?17.1% ± 16.7% for the RT3 and ?20.0 ± 44.6% for the TriTrac‐R3D. Correlation for PAEE between RT3 and DLW was higher than between TriTrac‐R3D and DLW (r = 0.67, p < 0.05 and r = 0.36, p = 0.25, respectively). The 95% confidence interval (CI) (kcal/d) of the mean difference between methods was large, amounting to ?385 to 145 for the RT3 and ?887 to 590 for the TriTrac‐R3D. In Experiment 2, both accelerometers were sensitive to the changes in treadmill speed, with no significant difference in mean PAEE between methods in overweight/obese subjects. Conclusions: Although both accelerometers did not provide accurate estimates of PAEE at individual levels, the data suggest that RT3 has the potential to assess PAEE at group levels in overweight/obese subjects.