Higher Respiratory Quotient Research Articles

Prognostic significance of respiratory quotient in patients undergoing extracorporeal cardiopulmonary resuscitation in Korea.

Respiratory quotient (RQ) may be used as a tissue hypoxia marker in various clinical settings but its prognostic significance in patients undergoing extracorporeal cardiopulmonary resuscitation (ECPR) is not known. Medical records of adult patients admitted to the intensive care units after ECPR in whom RQ could be calculated from May 2004 to April 2020 were retrospectively reviewed. Patients were divided into good neurologic outcome and poor neurologic outcome groups. Prognostic significance of RQ was compared to other clinical characteristics and markers of tissue hypoxia. During the study period, 155 patients were eligible for analysis. Of them, 90 (58.1%) had a poor neurologic outcome. The group with poor neurologic outcome had a higher incidence of out-of-hospital cardiac arrest (25.6% vs. 9.2%, P=0.010) and longer cardiopulmonary resuscitation to pump-on time (33.0 vs. 25.2 minutes, P=0.001) than the group with good neurologic outcome. For tissue hypoxia markers, the group with poor neurologic outcome had higher RQ (2.2 vs. 1.7, P=0.021) and lactate levels (8.2 vs. 5.4 mmol/L, P=0.004) than the group with good neurologic outcome. On multivariable analysis, age, cardiopulmonary resuscitation to pump-on time, and lactate levels above 7.1 mmol/L were significant predictors for a poor neurologic outcome but not RQ. In patients who received ECPR, RQ was not independently associated with poor neurologic outcome.

Cytarabine induces cachexia with lipid malabsorption via zippering the junctions of lacteal in murine small intestine

Chemotherapy-induced cachexia causes severe metabolic abnormalities independently of cancer and reduces the therapeutic efficacy of chemotherapy. The underlying mechanism of chemotherapy-induced cachexia remains unclear. Here we investigated the cytarabine (CYT)-induced alteration in energy balance and its underlying mechanisms in mice. We compared energy balance-associated parameters among the three groups of mice: CON, CYT, and PF (pair-fed mice with the CYT group) that were intravenously administered vehicle or CYT. Weight gain, fat mass, skeletal muscle mass, grip strength, and nocturnal energy expenditure were significantly lowered in the CYT group than in the CON and PF groups. The CYT group demonstrated less energy intake than the CON group and higher respiratory quotient than the PF group, indicating that CYT induced cachexia independently from the anorexia-induced weight loss. Serum triglyceride was significantly lower in the CYT group than in the CON group, whereas the intestinal mucosal triglyceride levels and the lipid content within the small intestine enterocyte were higher after lipid loading in the CYT group than in the CON and PF groups, suggesting that CYT inhibited lipid uptake in the intestine. This was not associated with obvious intestinal damage. The CYT group showed increased zipper-like junctions of lymphatic endothelial vessel in duodenal villi compared to that in the CON and CYT groups, suggesting their imperative role in the CYT-induced inhibition of lipid uptake. CYT worsens cachexia independently of anorexia by inhibiting the intestinal lipid uptake, via the increased zipper-like junctions of lymphatic endothelial vessel.

Energy Homeostasis-Associated (Enho) mRNA Expression and Energy Homeostasis in the Acute Stress Versus Chronic Unpredictable Mild Stress Rat Models.

The energy homeostasis-associated (Enho) gene, the transcript for the Adropin peptide, is usually linked to energy homeostasis, adiposity, glycemia, and insulin resistance. Studies on Enho expression in stressful conditions are lacking. This work aimed to investigate Enho mRNA expression and energy homeostasis in acute stress (AS) versus chronic unpredictable mild stress (CUMS) rat models. A total of thirty male Wistar rats (180-220 g) were fed a balanced diet with free access to water. Rats were divided into three equal groups (n = 10): (a) the normal control (NC) group; (b) the AS group, where one episode of stress for 2 h was applied; and (c) the CUMS group, in which rats were exposed to a variable program of mild stressors for 4 weeks. Energy homeostasis was analyzed by the PhenoMaster system for the automatic measuring of food intake (FI), respiratory O2 volume (VO2), CO2 volume (VCO2), respiratory quotient (RQ), and total energy expenditure (TEE). Finally, liver, whole brain, and adipose (WAT) tissue samples were collected, total RNA was prepared, and RT-PCR analysis of the Enho gene was performed. The CUMS group showed higher VO2 consumption and VCO2 production, and a higher RQ than the AS group. Furthermore, the TEE and FI were higher in the CUMS group compared to the AS group. Enho gene expression in the liver, brain, and WAT was significantly higher in the CUMS group than in the AS and NC groups. We can conclude that in the chew-fed AS rats, hypophagia was evident, with a shift in the RQ toward fat utilization, with no changes in body weight despite the increase in Enho mRNA expression in all studied tissues. In the CUMS group, the marked rise in Enho mRNA expression may have contributed to weight loss despite increased FI and TEE.

Cellular Stress Assay in Peripheral Blood Mononuclear Cells: Factors Influencing Its Results.

Cellular stress is central to the understanding of pathological mechanisms and the development of new therapeutic strategies and serves as a biomarker for disease progression in neurodegeneration, diabetes, cancer, cardiovascular and other chronic diseases. The common cellular stress assay (CSA) based on Seahorse technology in peripheral blood mononuclear cells (PBMCs) shows inconsistent results, which prevents its use as a biomarker for the progression of chronic diseases. Therefore, the aim of this study was to investigate potential factors that affect the CSA in PBMCs. We measured the CSA parameters in PBMCs from study participants and compared the results according to the potential factors, namely, the PBMC isolation method, age, seasonal variation and the gender of the study participants. PBMCs were isolated by OptiPrep® and RobosepTM-S methods. PBMCs isolated with the OptiPrep method showed much higher extracellular acidification and higher respiration compared to Robosep-isolated cells. Moreover, OptiPrep-isolated cells showed a higher number of outliers for the proton production rate (PPR) and a high respiratory quotient, indicating impurities with other cells, such as platelets, and technical inconsistencies. PBMCs from older individuals showed higher maximal respiration, spare capacity and extracellular acidification than younger participants. Additionally, in winter, maximal respiration and spare capacity decreased. From spring until early autumn, spare capacity and maximal respiration continuously increased. Elderly males also showed higher basal respiration, spare capacity and extracellular acidification than females. In conclusion, the findings of this study clearly demonstrate that the results of CSA parameters measured in PBMCs are influenced by the PBMC isolation method, age, seasonal variation and gender. Therefore, we recommend that researchers and physicians properly interpret the results of CSA parameters in PBMCs by considering these factors. It is important to use separate CSA evaluation standards based on the isolation method, age, gender and season-dependent factors. To assess the cellular stress situation in PBMCs, both extracellular acidification and mitochondrial respiration should be taken into account. Further study of additional factors, such as mitochondrial mass, should be conducted to improve the measurement of CSA parameters for the assessment of the real mitochondrial fitness.

Food insecurity is associated with higher respiratory quotient and lower glucagon-like peptide 1.

Food insecurity is known to be associated with obesity, but its association with physiological measures is unclear. Therefore, it was hypothesized that, compared with food-secure individuals, those with food insecurity would have higher 24-hour energy expenditure (EE [kilocalories per day]) and 24-hour respiratory quotient (RQ [ratio]). Subsequently, hormones involved in appetite regulation, substrate oxidation, and EE were explored. A total of 113 healthy participants without diabetes (75 men; mean [SD], age 40 [12] years; BMI 30 [8] kg/m2 ) were included in this analysis. Participants completed the Food Security Short Form, underwent a dual-energy x-ray absorptiometry scan, and spent 24 hours in a human respiratory chamber following a weight-maintaining diet. Compared with individuals with food security, participants with food insecurity had no difference in 24-hour EE. However, they had higher carbohydrate oxidation rates (p = 0.03) and lower lipid oxidation rates (p = 0.02), resulting in higher 24-hour RQ (p < 0.01). They also had lower fasting glucagon-like peptide 1 (p = 0.03) concentrations. Food insecurity is associated with higher 24-hour RQ and lower fasting glucagon-like peptide 1 concentrations, metabolic and hormonal differences previously shown to drive greater calorie intake in the setting of unrestricted food availability. These findings therefore provide new insight into the paradoxical link between restricted food access and increased adiposity.

Differences in muscle energy metabolism and metabolic flexibility between sarcopenic and nonsarcopenic older adults.

BackgroundMetabolic flexibility is the ability of skeletal muscle to adapt fuel utilization to the demand for fuel sources [carbohydrates (CHO) and fats (FAT)]. The purpose of this study was to explore muscle energy metabolism and metabolic flexibility under various conditions in sarcopenic (S) versus nonsarcopenic (NS) older adults.MethodsTwenty‐two older adults aged 65 years or older were categorized as NS [n = 11; mean ± standard deviation (SD); age = 73.5 ± 6.0 years (males, n = 5; females, n = 6)] or S [n = 11; 81.2 ± 10.5 years (males, n = 6; females, n = 5) based on handgrip strength, body composition and physical performance. Indirect calorimetry was recorded before and after consumption of a high‐CHO meal and during aerobic and anaerobic exercise. Respiratory quotient (RQ), CHO and FAT oxidation were assessed. Venous blood samples were collected for glucose and insulin concentrations.ResultsAt rest, compared with NS, S exhibited a 5–8% higher RQ at 0 (0.72 vs. 0.76) and 120 (0.77 vs. 0.82), 150 (0.76 vs. 0.80), and 180 min (0.74 vs. 0.80) (P = 0.002–0.025); 59–195% higher CHO oxidation at 0, 120, and 180 min (0.0004–0.002 vs. 0.001–0.002 g·min−1·kg‐1) (P = 0.010–0.047); and 20–31% lower FAT oxidation at 0, 15, and 90–180 min (0.0009–0.0022 vs. 0.0011–0.002 g·min−1·kg−1) (P = 0.004–0.038). Glucose levels were significantly elevated in S versus NS at 0, 60 and 75 min (144.64–202.78 vs. 107.70–134.20 mg·dL−1) but not insulin. During aerobic exercise, RQ was 5% greater (0.90 vs. 0.86) (P = 0.039), and FAT oxidation was 35% lower at 6–8 min (0.003 vs. 0.005 g·min−1·kg−1) (P = 0.033) in S versus NS. During anaerobic exercise, CHO oxidation was 31% greater in NS versus S at 60–80% time to exhaustion (0.011 vs. 0.007 g·min−1·kg−1) (P = 0.015). Per cent contribution to energy expenditure was greater in S for CHO but lower for FAT at 0 (CHO: 22% vs. 10%; FAT: 78% vs. 91%) and 120–180 min (CHO: 35–42% vs. 17–25%; FAT: 58–65% vs. 75%–84%) (P = 0.003–0.046) at rest and 6–8 min during aerobic exercise (CHO: 70% vs. 57%; FAT: 30% vs. 45%) (P = 0.046).ConclusionsThe data show differences in skeletal muscle energy metabolism and substrate utilization between S and NS at rest, transitioning from fasted to fed state, and during exercise. Compared with NS, S displayed a diminished ability to adapt fuel utilization in response to feeding and exercise, reflecting metabolic inflexibility. Impaired metabolic flexibility could be a mechanism underlying the losses of strength and physical function accompanying sarcopenia.

Respiratory quotient level variation during storage: Critical period for low oxygen tolerance, metabolism, and quality of ‘Galaxy’ apples

New technologies for apple preservation include storage under dynamic controlled atmosphere (DCA) with respiratory quotient (RQ) monitoring or chlorophyll fluorescence (CF). Therefore, this study aimed to evaluate the effects of RQ variation on the metabolism, overall quality, and volatile organic compound concentration of ‘Galaxy’ apples after long-term storage and compare them to fixed RQ levels, controlled atmosphere (CA), and DCA-CF. We also aimed to identify the period during storage in which apples are more susceptible to low oxygen damage. Fruit were evaluated after nine months of storage plus 7 d of shelf life at 20 °C. Higher RQ (1.5 and 2.0) levels throughout the storage period or the first three months resulted in higher anaerobic metabolism, increasing the internal disorders and reducing overall fruit quality, healthy fruit and flesh firmness. The results evidenced that the critical period for low oxygen damage is the first three months of storage. Overall fruit quality is better maintained when fruit were stored under DCA-CF, DCA-RQ 1.1, DCA-RQ 1.3, and changing RQ from 1.1; 1.3; 1.5, being three months at each RQ level. Moreover, more healthy fruit, higher flesh firmness, and lower physiological disorders were observed under these storage conditions, although the main ester accumulation was reduced. In general, higher 2-methylbutyl acetate and butyl acetate were observed in fruit stored under CA and high RQ levels (1.5 and 2.0). This demonstrates that even with RQ level variations during storage, it was not possible to obtain apples with high overall quality and ester concentrations under the same storage condition.

IMPACT OF SINGLE AND TWO-PHASE DISSOLVED OXYGEN TENSION CONTROL ON Bacillus thuringiensis CULTIVATION AND δ-ENDOTOXIN PRODUCTION

Constant δ-endotoxin production is crucial in Bacillus thuringiensis cultivation with aeration strategy playing a significant role in the process. In this study, the impact of DOT control strategies on the cultivation performance of B. thuringiensis was investigated using a 5-L stirred tank bioreactor. Single-phase DOT control recorded low spore count (&lt;5.0 × 1011 spore/mL) and low percentage of sporulation (&lt;45%). Two-stage DOT control cultivation with DOT at 80% during the active growth phase, followed by a switch to 60% or 40% at mid-exponential growth phase contributed to enhanced sporulation (&gt;60%), high maximum cell count (1.5 cfu/mL) with δ-endotoxin formed as early as 8 hr of cultivation. A high maximum specific growth rate, μmax (&gt;0.1 h-1) was also essential in ensuring δ-endotoxin production. High cell count obtained in cultivation with DOT level of 80% saturation during active growth was concurrent with high cell count, high μmax, fast generation time, high OUR, high CER value, and high respiratory quotient (RQ) value. During the two-phase DOT control cultivation, low RQ values were reported. The result showed that the exhaust gas data could be used to monitor B. thuringiensis cultivation performance.

Veno-arterial CO2 difference and respiratory quotient after cardiac arrest: An observational cohort study.

To characterize venous-arterial CO2 difference (ΔpCO2) and the respiratory quotient (RQ) in post cardiac arrest patients and evaluate the association between these parameters and patient outcome. Data were obtained retrospectively from post cardiac arrest patients admitted between 2007 and 2016 to a medical intensive care unit. Comatose, adult patients in whom arterial and venous blood gas analyses were concomitantly performed in the first 24h were included. Patients were grouped according to the time-point of sampling; 0-6, 6-12 and 12-24h after admission. 308 patients were included; 174 (56%) died before ICU discharge and 212 (69%) had an unfavorable neurologic outcome. RQ was associated with ICU mortality (OR:1.09 (95%CI: 1.04-1.14; p<0.01)), although not with neurological outcome. ΔpCO2 was negatively associated with both ICU mortality (OR: 0.92 (95%CI: 0.86-0.99; p=0.02)) and poor neurologic outcome (adjusted OR: 0.93 (95%CI: 0.87-0.99; p=0.02)). ΔpCO2 predicted an elevated RQ; a ΔpCO2 above 8.5mmHg identified a high RQ with reasonable sensitivity and specificity. RQ was associated with ICU mortality and ΔpCO2 identified elevated RQ in the early phase after cardiac arrest. However, ΔpCO2 were negatively associated with both ICU mortality and neurologic outcome.

A retrospective analysis of CO2 derived goal-directed perfusion variables under normothermic conditions: do we need to re-evaluate threshold values?

This study investigated if current predictive values for increased lactate formation: VCO2i > 60 ml min-1 m-2, respiratory quotient (RQ) > 0.90, and DO2/VCO2 < 5.0, are valid under normothermic conditions. CO2 derived parameters were analyzed in 91 patients undergoing normothermic CABG and related to increase of blood lactate concentrations during bypass. In this study population, 85 patients (93%) had a median VCO2i above 60 ml min-1 m-2 and 53 patients (58%) had a DO2/VCO2 ⩽ 5.0. Eighteen patients (20%) had a median RQ ⩾ 0.90, but RQ remained with a maximum value of 0.94 below the biological threshold of 1.0. Increase of lactate concentrations remained without clinical significance and showed weak correlations with VCO2i (rs = 0.277, p = 0.008) and RQ (rs = 0.346, p = 0.001).The cohort was separated for the different CO2 variables by their median value to compare increase in lactate concentration. Patients with a high VCO2i (⩾70 ml min-1 m-2) and a high RQ (⩾0.82) showed significant higher increase in lactate concentration compared to patients with VCO2i < 70 ml min-1 m-2 (p = 0.004), and a RQ < 0.82 (p = 0.012). Groups separated by a median DO2/VCO2 of 4.8 did not show a difference in increase of lactate concentration in blood. In summary, specific CO2 derived threshold values for the prediction of lactate formation, which have been reported in other studies, cannot be confirmed with our findings. However, a CO2 production ⩾70 ml min-1 m-2 and a RQ ⩾ 0.82 in this study population were correlated with increased lactate formation. Because CO2 production during bypass depends on patient temperature, a different cutoff value, that may take into account the influence of demographic variables, should be determined during normothermic CPB.

The aging mouse microbiome has obesogenic characteristics

BackgroundDuring aging, there is a physiological decline, an increase of morbidity and mortality, and a natural change in the gut microbiome. In this study, we investigated the influence of the gut microbiome on different metabolic parameters in adult and aged mice.MethodsFecal and blood samples from adult (n = 42, 100–300 days) and aging (n = 32, 550–750 days) mice were collected. Microbiome analysis was done using QIIME2. Mouse weight and body composition were measured using NMR, and insulin and leptin levels in the blood were measured with Mouse Adipokine Magnetic Bead Panel kit. Fecal microbiota transplantation experiments from adult and aged mice into young germ-free mice were carried out in order to examine the effect of the gut microbiome of adult and aging mice on weight, body composition, insulin, and leptin.ResultsWe demonstrate that the microbiomes from adult and aged mice are distinguishable. We also report changes in metabolic parameters as we observed significantly higher weight and fat mass and low lean mass in aged compared to adult mice along with high insulin and leptin levels in the blood. The transplanted gut microbiome from aged mice transferred part of the phenotypes seen in aged mice. Fat body mass and insulin levels were higher in the mice who received feces from aged mice than mice receiving feces from adult mice. In addition, they consumed more food and had a higher respiratory quotient compared to mice receiving adult feces.ConclusionsWe conclude that aged mice have a gut microbiota with obesogenic characteristics. In addition, the gut bacterial population itself is sufficient to induce some of the manifestations of obesity.

Comparative study of physiologic characteristics between the newly compiled Bafa Wubu of tai chi and 24 form simplified tai chi

BackgroundThe newly compiled Bafa Wubu of Tai Chi (Eight Methods and Five Footworks) is a fitness routine that has been developed in accordance with the appeal of the General Administration of Sport of China and promoted both in China and abroad. This paper aims to compare the differences in energy consumption and related parameters between the two types of Tai Chi.MethodsA total of 60 healthy participants were recruited; 37 males (aged 37.4 ± 10.4 years) and 23 females (aged 31.9 ± 12.8 years). The maximal exercise capacity of participants was measured at baseline. Then, they received Tai Chi training for 12-week and their energy metabolism was measured dynamically.ResultsA set of the Bafa Wubu of Tai Chi requires approximately 3 min, while a set of 24 form simplified Tai Chi approximately 5 min and 40 s. The average oxygen uptake/kg (VO2/kg, 10.8 ± 2.52 ml/kg/min vs. 12.9 ± 2.59 ml/kg/min, P = 0.000), the highest VO2/kg (19.3 ± 6.03 ml/kg/min vs. 24.1 ± 7.50 ml/kg/min, p = 0.000, the average metabolic equivalent (METs,2.3 ± 0.16 METs vs. 3.2 ± 0.14 METs, p = 0.000), the highest oxygen pulse (VO2/HR, 11.1 ± 0.99 ml vs. 13.9 ± 0.93 ml, p = 0.000) and rate of perceived exertion (RPE, 10.7 ± 0.70 vs. 1.3 ± 0.62, p = 0.000) gained immediately after Bafa Wubu of Tai Chi exercise were significantly lower than those in 24 form simplified Tai Chi; heart rate recovery (HRR,1.5 ± 0.41 vs. 1.3 ± 0.45, p = 0.008) at 1 min after the practice was significantly higher than after the 24 form simplified Tai Chi. Meanwhile, the average heart rate (HR, 104.1 ± 11.41 bpm vs. 105.7 ± 9.68 bpm, p = 0.696) and the highest respiratory quotient (RQ, 1.0 ± 0.06 vs. 0.9 ± 0.09, p = 0.643) were not significantly different. The intensity of Tai Chi was described as the highest oxygen uptake of the participants when they performed the Tai Chi divided by their individual maximal oxygen uptake. Tai Chi intensity during Bafa Wubu of Tai Chi (50% ± 11.7% vs. 64% ± 12.5%) was significantly lower than during 24 form simplified Tai Chi.ConclusionThe newly compiled Bafa Wubu of Tai Chi is characterized by lower energy consumption than 24 form simplified Tai Chi.Trial registrationEthics Committee of Sports Science Experiment, Beijing Sport University- 2018010H. Registered 19 June 2018

0132 Sex Differences in Evening Food Intake and Associated Weight Gain During Insufficient Sleep

Abstract Introduction Timing of food intake has emerged as a novel risk factor for weight gain and obesity. Higher evening food intake, especially during insufficient sleep, is associated with weight gain. We aimed to explore initial changes in evening food intake and the respiratory quotient (RQ) during insufficient sleep and subsequent weight gain. We also explored sex differences. Methods 28 healthy adults (14F) aged 26.3±4.5y completed a 14–16 daylong laboratory protocol. In their home environment participants maintained one week of ~9h/night sleep schedules and consumed energy balanced diets for 3 days prior to completing the laboratory protocol. The laboratory protocol consisted of 3 baseline days of 9h/night scheduled sleep with energy balanced diets followed by 10 days of 5h/night scheduled sleep with ad-libitum food intake, with (n=14) and without (n=14) weekend recovery sleep. RQ was assessed on days 3 and 5 in a whole room calorimeter. Evening (dinner and after-dinner snacks) energy intake and body weight were assessed daily. Results A significant sex by condition effect was observed for evening food intake such that men and women were similar at baseline, but men ate more than women during insufficient sleep, when controlling for body mass (p&amp;lt;0.05). A significant sex by condition effect was also observed for RQ with women showing similar RQ during baseline and insufficient sleep and men showing a higher RQ during insufficient sleep versus baseline (p&amp;lt;0.05). Linear regression with food intake and RQ as predictors of weight gain showed that increased evening food intake, but not RQ, on the second day of sleep restriction was associated with weight gain in men, but not women, at the end of the study eight days later (p&amp;lt;0.05). Conclusion Findings suggest that rapid changes in evening food intake during insufficient sleep contributes to subsequent weight gain during sustained insufficient sleep, especially in men. Support NIH HL109706, DK111161, TR001082, DK048520, Sleep Research Society Foundation grant 011-JP-16 and Office of Naval Research MURI (N00014-15-1-2809).

Preoperative high respiratory quotient correlates with lower weight loss after bariatric surgery.

The respiratory coefficient (RQ), as determined by indirect calorimetry (IC), classifies diet as being carbohydrate rich (RQ = 0.7-0.8), fat rich (RQ = 0.9-1.0), or overfeeding (RQ > 1). We hypothesized that preoperative RQ may be associated with weight-loss outcomes after bariatric surgery. From 2016 to 2018, 137 obese patients were enrolled in a Bariatric Registry and underwent dietary and behavioral counseling, followed by preoperative IC. Resting energy expenditure (REE) and RQ of all patients was measured. Patients were classified as over-feeders (OF; 42, 31%) with RQ > 1 or non-over-feeders (NOF; 95, 69%) with RQ < 1. At baseline, there was no difference between groups in gender [female: 105 (76.6%), male: 32 (23.4%)], body mass index (BMI; OF: 46.8 ± 7.8 vs. NOF: 44.8 ± 7.4kg/m2, p = 0.40), or baseline REE (OF: 1897 ± 622 vs. NOF: 1874 ± 579, p = 0.74), although OF were younger [mean age (OF: 47.1 ± 13.0 years vs. NOF: 43.1 ± 13.4; p = 0.009). At 6-month follow-up 94 patients [53.28%; OF: 35 (83%) vs. NOF: 59 (62%), p = 0.016] were seen and 48 [35.03%; OF: 23 (55%) vs. NOF: 25 (59%), p = 0.001] at 12-month follow-up. On preoperative psychological assessment, OF had a significantly higher rate of childhood neglect (OF: 28 (47.46%) vs. NOF: 40 (28.99%); p = 0.01). At 1year postoperatively, the OF had a significantly higher BMI (OF: 34.3 ± 6.5 vs. NOF: 29.3 ± 5.1kg/m2, p = 0.009). Differences in weight were not significant at 6-month (OF: 36.0 ± 6.5 vs. NOF: 33.5 ± 5.9kg/m2, p = 0.07). There was no difference between type of operation and RQ group (RYGB; OF: 55 (75%) vs. NOF: 18 (25%) and SG; OF: 40 (62%) vs. NOF: 24 (38%), p = 0.14), nor in BMI loss after operation. Evidence of overfeeding in the preoperative period prior to bariatric surgery is associated with higher resultant BMI at 1year. Calculation of the RQ with IC has prognostic significance in bariatric surgery, and calculation of REE based on assumed normal RQ potentiates error. It is unclear if overfeeding is purely behavioral or secondary to potentially reversible metabolic etiology.

Low capacity to oxidize fat and body weight.

For a given positive energy balance, a low capacity to oxidize fat could contribute to weight gain (low fat oxidation hypothesis). This hypothesis is based on the arguments that for a given stable diet and food quotient (FQ), the respiratory quotient (RQ) is higher in obesity prone (OP) than in obesity resistant individuals (OR) and that a high RQ predicts higher future weight gain. A review of 42 studies shows that there is no convincing experimental support to these arguments and thus for the low fat oxidation hypothesis. A power analysis also shows that this hypothesis might be impossible to experimentally confirm because very large numbers of subjects would be needed to reject the null hypotheses that the 24-h RQ is not different in OP and OR or that future weight gain is not different in individuals with a low and high 24-h RQ at baseline. A re-examination of the significance of the 24-hour and fasting RQ also shows that the assumption underlying the low fat oxidation hypothesis that a high RQ reflects a low capacity to oxidize fat is not valid: For a stable diet, the 24-h RQ entirely depends on FQ and energy balance, and the fasting RQ mainly depends on the FQ and energy balance and on the size of glycogen stores.

Effects of an individualized nutrition intervention on the respiratory quotient of patients with liver failure.

Malnutrition and energy metabolism disorders are characterized by a low respiratory quotient in patients with liver failure and often lead to poor prognosis. Therefore, early nutrition interventions are crucial for patients with liver failure to ameliorate abnormal metabolic status and malnutrition. This study explored the effect of an individualized nutrition intervention on the respiratory quotient of patients with liver failure. An individualized 2-week nutrition intervention was conducted on patients with nutritional risk caused by liver failure according to patient resting energy expenditure. Patients were separated into two groups for further analysis according to whether their energy intake reached 1.2 times their resting energy expenditure. Fifty-two patients with nutritional risk caused by liver failure were enrolled. Their average respiratory quotient was 0.79 (0.76-0.84) at the baseline. Patients with an energy intake of >=1.2 times their resting energy expenditure had a higher respiratory quotient and lower scores on the model for endstage liver disease and Child-Pugh test than those with an energy intake of <1.2 times their resting energy expenditure at weeks 1 and 2 after the intervention. Moreover, no significant differences were observed between the two groups at the baseline. Respiratory quotient was negatively correlated with the model for end-stage liver disease and Child-Pugh scores. Individualized nutrition interventions with an energy intake >=1.2 times the patient's resting energy expenditure can effectively improve the respiratory quotient and reduce disease severity in patients with nutritional risk caused by liver failure.

Lipid Oxidation Assessed by Indirect Calorimetry Predicts Metabolic Syndrome and Type 2 Diabetes.

Purpose: Diabetes has been linked to an impaired ability to oxidize fatty acids. Fat oxidation can be assessed clinically by a respiratory quotient measurement during fasting. We hypothesized that a respiratory quotient might predict metabolic syndrome and type 2 diabetes onset.Methods: In this longitudinal study we used an existing database of 233 individuals who had complete nutritional and biochemical data at baseline and after 12-month follow-up. All participants underwent an indirect calorimetry to measure the respiratory quotient. We excluded participants with diabetes, metabolic syndrome, chronic diseases, and those who had changed food habits in the previous 3 months. Only 88 subjects met the inclusion criteria.Results: Two individuals developed type 2 diabetes and 10 metabolic syndrome after 1 year. Participants in the high respiratory quotient group (>0.91) had a higher incidence of metabolic syndrome/diabetes than those in the low quotient group (25 vs. 8% p = 0.04). In this group, mean basal respiratory quotient was 0.97 ± 0.04. In the high respiratory quotient group, Kaplan-Meier curves showed a greater probability of having metabolic syndrome/diabetes than those in the low respiratoryquotient group (log Rank χ2-test = 8.44; p = 0.004). A multivariable Cox proportional hazards model demonstrated that energy expenditure and weight increase did not predict metabolic syndrome/diabetes [HR (95% CI) = 1 (0.996–1.005), p = 0.86 and 3.9 (0.407–38.061), p = 0.23, respectively).Conclusions: A greater probability of metabolic syndrome/diabetes was found in individuals with a basal respiratory quotient of >0.91 than in those with a respiratoryquotient of ≤ 0.91 after 1 year. In the short-term anthropometric measurements and their variation overtime were not correlated with metabolic syndrome/diabetes.

A rotating light cycle promotes weight gain and hepatic lipid storage in mice.

Processes involved in regulation of energy balance and intermediary metabolism are aligned to the light-dark cycle. Shift-work and high-fat diet (HFD)-induced obesity disrupt circadian rhythmicity and are associated with increased risk of nonalcoholic fatty liver disease. This study aimed to determine the effect of simulating shift work on hepatic lipid accumulation in lean and HFD mice. C57BL/6 mice fed a standard laboratory diet (SLD) or HFD for 4 wk were further allocated to a normal light (NL) cycle (lights on: 0600-1800) or rotating light (RL) cycle [3 days NL and 4 days reversed (lights on: 1800-0600) repeated] for 8 wk. Tissue was collected every 3 h beginning at 0600. HFD mice gained more weight than SLD mice, and RL mice gained more weight than NL mice. SLD-NL and HFD-NL mice, but not RL mice, were more active, had higher respiratory quotients, and consumed/expended more energy during the dark phase compared with the light phase. Blood glucose and plasma cholesterol and triglyceride concentrations were elevated in HFD and SLD-RL compared with SLD-NL mice. Hepatic glycogen was elevated in HFD compared with SLD mice. Hepatic triglycerides were elevated in SLD-RL and HFD mice compared with SLD-NL. Circadian rhythmicity of hepatic acetyl-CoA carboxylase (ACACA) mRNA was phase shifted in SLD-RL and HFD-NL and lost in HFD-RL mice. Hepatic ACACA protein was reduced in SLD-RL and HFD mice compared with SLD-NL mice. Hepatic adipose triglyceride lipase was elevated in HFD-NL compared with SLD-NL but lower in RL mice compared with NL mice irrespective of diet. In conclusion, an RL cycle model of shift work promotes weight gain and hepatic lipid storage even in lean conditions. NEW & NOTEWORTHY In this publication we describe the effects of a rotating light cycle model of shift work in lean and high-fat diet-induced obese mice on body mass, diurnal patterns of energy intake and expenditure, and hepatic lipid storage. The data indicate that modeling shift work, via a rotating light cycle, promotes weight gain and hepatic lipid accumulation even in mice on a standard laboratory diet.

Absence of leptin signaling allows fat accretion in cystic fibrosis mice.

Negative energy balance is a prevalent feature of cystic fibrosis (CF). Pancreatic insufficiency, elevated energy expenditure, lung disease, and malnutrition, all characteristic of CF, contribute to the negative energy balance causing low body-growth phenotype. As low body weight and body mass index strongly correlate with poor lung health and survival of patients with CF, improving energy balance is an important clinical goal (e.g., high-fat diet). CF mouse models also exhibit negative energy balance (growth retardation and high energy expenditure), independent from exocrine pancreatic insufficiency, lung disease, and malnutrition. To improve energy balance through increased caloric intake and reduced energy expenditure, we disrupted leptin signaling by crossing the db/db leptin receptor allele with mice carrying the R117H Cftr mutation. Compared with db/db mice, absence of leptin signaling in CF mice (CF db/db) resulted in delayed and moderate hyperphagia with lower de novo lipogenesis and lipid deposition, producing only moderately obese CF mice. Greater body length was found in db/db mice but not in CF db/db, suggesting CF-dependent effect on bone growth. The db/db genotype resulted in lower energy expenditure regardless of Cftr genotype leading to obesity. Despite the db/db genotype, the CF genotype exhibited high respiratory quotient indicating elevated carbohydrate oxidation, thus limiting carbohydrates for lipogenesis. In summary, db/db-linked hyperphagia, elevated lipogenesis, and morbid obesity were partially suppressed by reduced CFTR activity. CF mice still accrued large amounts of adipose tissue in contrast to mice fed a high-fat diet, thus highlighting the importance of dietary carbohydrates and not simply fat for energy balance in CF. NEW & NOTEWORTHY We show that cystic fibrosis (CF) mice are able to accrue fat under conditions of carbohydrate overfeeding, increased lipogenesis, and decreased energy expenditure, although length was unaffected. High-fat diet feeding failed to improve growth in CF mice. Morbid db/db-like obesity was reduced in CF double-mutant mice by reduced CFTR activity.

Impact of Type 1 Diabetes on 24-Hour Energy Expenditure and Metabolic Flexibility

Type 1 diabetes (T1D) is associated with an increase in resting metabolic rate, but the impact of T1D on other components of 24-hour energy expenditure (EE) and metabolic flexibility (MF) is not known. We measured 24-hour EE, its components and substrate oxidation rates in 11 patients with T1D and 12 nondiabetic, age and BMI matched controls (HC) using whole room calorimetry. MF was defined as the respiratory quotient (RQ) kinetic response after ingesting a standard high CHO breakfast. Briefly, the kinetics between the lowest RQ pre-breakfast and the highest RQ after breakfast were analyzed by a simple linear regression between time (1-minute resolution) and RQ units (RQUnits). Subjects with T1D had marginally higher 24-hour EE and higher 24-hour non-exercise EE, but sleeping EE and basal EE were not significantly different (Table 1). There were no differences in 24-h respiratory quotient (RQ) or sleeping RQ, but MF during the breakfast meal was significantly lower in T1D vs. HC (p=0.042). Among patients with T1D, MF was related to the glycemic response to breakfast. These data suggest that T1D is characterized by alterations in EE and MF. These results have implications for glycemic and weight management among patients with T1D. Disclosure E.A. Carnero: None. K.D. Corbin: None. C.P. Bock: None. S.R. Smith: None. R.E. Pratley: Other Relationship; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eisai Inc., GlaxoSmithKline plc., Janssen Pharmaceuticals, Inc., Lexicon Pharmaceuticals, Inc., Ligand Pharmaceuticals, Inc., Eli Lilly and Company, Merck &amp; Co., Inc., Novo Nordisk Inc., Pfizer Inc., Sanofi-Aventis, Takeda Development Center Americas, Inc..