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Effect of Dietary Strategies on Respiratory Quotient and Its Association with Clinical Parameters and Organ Fat Loss: A Randomized Controlled Trial.
Goldenshluger, A, Constantini, K, Goldstein, N, Shelef, I, Schwarzfuchs, D, Zelicha, H, Yaskolka Meir, A, Tsaban, G, Chassidim, Y, Gepner, Y
Nutrients. 2021;(7)
Abstract
The relation between changes in respiratory quotient (RQ) following dietary interventions and clinical parameters and body fat pools remains unknown. In this randomized controlled trial, participants with moderate abdominal obesity or/and dyslipidemia (n = 159) were randomly assigned to a Mediterranean/low carbohydrate (MED/LC, n = 80) or a low fat (LF, n = 79) isocaloric weight loss diet and completed a metabolic assessment. Changes in RQ (measured by indirect calorimeter), adipose-tissue pools (MRI), and clinical measurements were assessed at baseline and after 6 months of intervention. An elevated RQ at baseline was significantly associated with increased visceral adipose tissue, hepatic fat, higher levels of insulin and homeostatic insulin resistance. After 6 months, body weight had decreased similarly between the diet groups (-6 ± 6 kg). However, the MED/LC diet, which greatly improved metabolic health, decreased RQ significantly more than the LF diet (-0.022 ± 0.007 vs. -0.002 ± 0.008, p = 0.005). Total cholesterol and diastolic blood pressure were independently associated with RQ changes (p = 0.045). RQ was positively associated with increased superficial subcutaneous-adipose-tissue but decreased renal sinus, pancreatic, and intramuscular fats after adjusting for confounders. Fasting RQ may reflect differences in metabolic characteristics between subjects affecting their potential individual response to the diet.
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No thermoregulatory or ergogenic effect of dietary nitrate among physically inactive males, exercising above gas exchange threshold in hot and dry conditions.
Fowler, R, Jeffries, O, Tallent, J, Theis, N, Heffernan, SM, McNarry, MA, Kilduff, L, Waldron, M
European journal of sport science. 2021;(3):370-378
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Abstract
The aim of this study was to determine the effect of five days dietary nitrate (NO3-) consumption on exercise tolerance and thermoregulation during cycling in hot, dry conditions. In a double-blind, randomised crossover design, 11 healthy males participated in an exercise tolerance test (Tlim) in the heat (35°C, 28% relative humidity), cycling above the thermoneutral gas exchange threshold, after five days of dietary supplementation, with either NO3-rich beetroot juice (BR; ∼ 9.2 mmol NO3-) or placebo (PLA). Changes in plasma [NO3-] and nitrite [NO2-], core and mean skin temperatures, mean local and whole-body sweat rates, heart rate, perceptual ratings and pulmonary gas exchange were measured during exercise, alongside calorimetric estimations of thermal balance. Mean arterial pressures (MAP) were recorded pre-Tlim. There were no differences in Tlim between conditions (BR = 22.8 ± 8.1 min; Placebo = 20.7 ± 7.9 min) (P = 0.184), despite increases in plasma [NO3-] and [NO2-] (P < 0.001) and a 3.8% reduction in resting MAP (P = 0.004) in the BR condition. There were no other differences in thermoregulatory, cardio-metabolic, perceptual or calorimetric responses to the Tlim between conditions (P > 0.05). Dietary NO3- supplementation had no effect on exercise tolerance or thermoregulation in hot, dry conditions, despite reductions in resting MAP and increases in plasma [NO3-] and [NO2-]. Healthy, yet physically inactive individuals with no known impairments in vasodilatory and sudomotor function do not appear to require BR for ergogenic or thermolytic effects during exercise in the heat.
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Influence of dietary nitrate supplementation on lung function and exercise gas exchange in COPD patients.
Behnia, M, Wheatley, CM, Avolio, A, Johnson, BD
Nitric oxide : biology and chemistry. 2018;:53-61
Abstract
BACKGROUND During exercise as pulmonary blood flow rises, pulmonary capillary blood volume increases and gas exchange surface area expands through distention and recruitment. We have previously demonstrated that pulmonary capillary recruitment is limited in COPD patients with poorer exercise tolerance. Hypoxia and endothelial dysfunction lead to pulmonary vascular dysregulation possibly in part related to nitric oxide related pathways. PURPOSE To determine if increasing dietary nitrate might influence lung surface area for gas exchange and subsequently impact exercise performance. METHODS Subjects had stable, medically treated COPD (n = 25), gave informed consent, filled out the St George Respiratory Questionnaire (SGRQ), had a baseline blood draw for Hgb, performed spirometry, and had exhaled nitric oxide (exNO) measured. Then they performed the intra-breath (IB) technique for lung diffusing capacity for carbon monoxide (DLCO) as well as pulmonary blood flow (Qc). Subsequently they completed a progressive semi-recumbent cycle ergometry test to exhaustion with measures of oxygen saturation (SpO2) and expired gases along with DLCO and Qc measured during the 1st work load only. Subjects were randomized to nitrate supplement group (beetroot juice) or placebo group (black currant juice) for 8 days and returned for repeat of the above protocol. RESULTS Exhaled nitric oxide levels rose >200% in the nitrate group (p < 0.05) with minimal change in placebo group. The SGRQ suggested a small fall in perceived symptom limitation in the nitrate group, but no measure of resting pulmonary function differed post nitrate supplementation. With exercise, there was no influence of nitrate supplementation on peak VO2 or other measures of respiratory gas exchange. There was a tendency for the exercise DLCO to increase slightly in the nitrate group with a trend towards a rise in the DLCO/Qc relationship (p = 0.08) but not in the placebo group. The only other significant finding was a fall in the exercise blood pressure in the nitrate group, but not placebo group (p < 0.05). CONCLUSION Despite evidence of a rise in exhaled nitric oxide levels with nitrate supplementation, there was minimal evidence for improvement in exercise performance or pulmonary gas exchange surface area in a stable medically treated COPD population.
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Pulmonary gas exchange after foam sclerotherapy.
Moro, L, Rossi Bartoli, I, Cesari, M, Scarlata, S, Serino, FM, Antonelli Incalzi, R
JAMA dermatology. 2014;(2):207-9
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Cardiorespiratory fitness is related to the risk of sudden cardiac death: a population-based follow-up study.
Laukkanen, JA, Mäkikallio, TH, Rauramaa, R, Kiviniemi, V, Ronkainen, K, Kurl, S
Journal of the American College of Cardiology. 2010;(18):1476-83
Abstract
OBJECTIVES Our aim was to examine the relation of cardiorespiratory fitness with sudden cardiac death (SCD) in a population-based sample of men. BACKGROUND Very limited information is available about the role of cardiorespiratory fitness in the prediction of SCD. METHODS This population study was based on 2,368 men 42 to 60 years of age. Cardiorespiratory fitness was defined by using respiratory gas exchange analyzer and maximal workload during cycle ergometer exercise test. RESULTS During the 17-year follow-up, there were 146 SCDs. As a continuous variable, 1 metabolic equivalent (MET) increment in cardiorespiratory fitness was related to a decrease of 22% in the risk of SCD (relative risk: 0.78, 95% confidence interval: 0.71 to 0.84, p<0.001). In addition to cardiorespiratory fitness, ischemic ST-segment depression during exercise testing, smoking, systolic blood pressure, prevalent coronary heart disease, family history of coronary heart disease, and type 2 diabetes mellitus were related to the risk of SCD. The Harrell C-index for the total model discrimination was 0.767, while cardiorespiratory fitness provides modest improvement (from 0.760 to 0.767) in the risk prediction when added with all other risk factors. The integrated discrimination improvement was 0.0087 (p=0.018, relative integrated discrimination improvement 0.11) when cardiorespiratory fitness was added in the model. However, the net reclassification index (-0.018) was not statistically significantly improved (p=0.703). CONCLUSIONS Cardiorespiratory fitness is a predictor of SCD in addition to that predicted by conventional risk factors. There was a slight improvement in the level of discrimination, although the net reclassification index did not change while using cardiorespiratory fitness with conventional risk factors.
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The effects of 4 weeks of an arginine-based supplement on the gas exchange threshold and peak oxygen uptake.
Camic, CL, Housh, TJ, Mielke, M, Zuniga, JM, Hendrix, CR, Johnson, GO, Schmidt, RJ, Housh, DJ
Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. 2010;(3):286-93
Abstract
The purpose of the present study was to examine the effects of the daily administration of an arginine-based supplement for 4 weeks on the gas exchange threshold (GET) and peak oxygen uptake. The study used a double-blind, placebo-controlled design. Forty-one college-aged males (mean age +/- SD = 22.1 +/- 2.4 years) were randomized into either the PLACEBO (n = 20) or ARGININE (n = 21) group. The placebo was microcrystalline cellulose. The ARGININE group ingested 3.0 g of arginine, 300 mg of grape seed extract, and 300 mg of polyethylene glycol. All subjects performed an incremental test to exhaustion on a cycle ergometer prior to supplementation (PRE) and after 4 weeks of supplementation (POST). The GET was determined by using the V-slope method of the carbon dioxide output vs. oxygen uptake relationship. The results indicated that there were significant mean increases (PRE to POST) in GET (4.1%), as well as in carbon dioxide output (4.3%) and power output (5.4%) at the GET for the ARGININE group, but no significant changes for the PLACEBO group (2.5%, 4.3%, and 3.9%, respectively). In addition, there were no significant changes in peak oxygen uptake for the ARGININE (-1.0%) or PLACEBO (-1.5%) groups. These findings supported the use of the arginine-based supplement for increasing GET and the associated power output, but not for increasing peak oxygen uptake during cycle ergometry.
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Influence of dichloroacetate on pulmonary gas exchange and ventilation during incremental exercise in healthy humans.
Wilkerson, DP, Campbell, IT, Blackwell, JR, Berger, NJ, Jones, AM
Respiratory physiology & neurobiology. 2009;(3):224-9
Abstract
We hypothesised that dichloroacetate (DCA) would reduce blood lactate accumulation, pulmonary carbon dioxide output (.V(CO2)) and ventilation (.V(E)) at sub-maximal work rates, and improve exercise tolerance during incremental exercise in healthy humans. Nine males (mean+/-SD, age 27+/-4 years) completed, in random order, two ramp incremental cycle ergometer tests to the limit of tolerance following the intravenous infusion of DCA (75 mg/kg body mass in 80 ml saline) or an equivalent volume of saline (as placebo). Relative to control, blood [lactate] was significantly reduced by DCA immediately before exercise (CON: 0.7+/-0.2 vs. DCA: 0.5+/-0.2mM; P<0.05) and throughout exercise until 630s (P<0.05). Blood [HCO(3)(-)] was significantly higher in the DCA condition from 360s until 720s of exercise (P<0.05). .V(CO2) and .V(E) were both lower throughout exercise in the DCA condition, with the differences reaching significance at 90 and 180s for .V(CO2) (P<0.05) and at 90, 180, 450, 540, 630, and 810s for .V(E) (P<0.05). Exercise tolerance was not significantly altered (CON: 1029+/-109 vs. DCA: 1045+/-101s). Infusion of DCA resulted in reductions in blood [lactate], .V(CO2) and .V(E) during sub-maximal incremental exercise, consistent with the existence of a link between the bicarbonate buffering of metabolic acidosis and increased CO(2) output. However, the reduced blood lactate accumulation during sub-maximal exercise with DCA did not enhance exercise tolerance.
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Effects on hemodynamics and gas exchange of omega-3 fatty acid-enriched lipid emulsion in acute respiratory distress syndrome (ARDS): a prospective, randomized, double-blind, parallel group study.
Sabater, J, Masclans, JR, Sacanell, J, Chacon, P, Sabin, P, Planas, M
Lipids in health and disease. 2008;:39
Abstract
INTRODUCTION We investigated the effects on hemodynamics and gas exchange of a lipid emulsion enriched with omega-3 fatty acids in patients with ARDS. METHODS The design was a prospective, randomized, double-blind, parallel group study in our Intensive Medicine Department of Vall d'Hebron University Hospital (Barcelona-Spain). We studied 16 consecutive patients with ARDS and intolerance to enteral nutrition (14 men and 2 women; mean age: 58 +/- 13 years; APACHE II score: 17.8 +/- 2.3; Lung Injury Score: 3.1 +/- 0.5; baseline PaO2/FiO2 ratio: 149 +/- 40). Patients were randomized into 2 groups: Group A (n = 8) received the study emulsion Lipoplus 20%, B.Braun Medical (50% MCT, 40% LCT, 10% omega-3); Group B (n = 8) received the control emulsion Intralipid Fresenius Kabi (100% LCT). Lipid emulsions were administered during 12 h at a dose of 0.12 g/kg/h. Measurements of the main hemodynamic and gas exchange parameters were made at baseline (immediately before administration of the lipid emulsions), every hour during the lipid infusion, at the end of administration, and six hours after the end of administration lipid infusion. RESULTS No statistically significant changes were observed in the different hemodynamic values analyzed. Likewise, the gas exchange parameters did not show statistically significant differences during the study. No adverse effect attributable to the lipid emulsions was seen in the patients analyzed. CONCLUSION The lipid emulsion enriched with omega-3 fatty acids was safe and well tolerated in short-term administration to patients with ARDS. It did not cause any significant changes in hemodynamic and gas exchange parameters. TRIAL REGISTRATION ISRCTN63673813.
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Mechanisms of functional loss in patients with chronic lung disease.
MacIntyre, NR
Respiratory care. 2008;(9):1177-84
Abstract
Functional loss (often quantified as exercise limitation) is common in patients with chronic lung disease. The factors involved are multiple and many may be present together in a given patient. Ventilatory factors involve an imbalance in load/capacity relationships. Specifically, breathing loads from abnormal respiratory-system mechanics and/or excessive ventilatory demand cannot be handled by respiratory muscles that are dysfunctional or malpositioned. Gas-exchange factors involve impaired ventilation-perfusion relationships that lead to hypoxemia, impaired oxygen delivery, and pulmonary hypertension. Cardiovascular factors involve coexisting intrinsic heart disease, right-ventricular overload from pulmonary vascular abnormalities, and simple deconditioning. Skeletal muscle (both respiratory and limb) factors involve direct inflammatory mediator effects on muscle function, malnutrition, blood-gas abnormalities, compromised oxygen delivery from right-heart dysfunction, electrolyte imbalances, drugs, and comorbid states. Other less well understood factors include excessive dyspnea, impaired motivation, orthopedic issues, and psychiatric issues.
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Glibenclamide dose response in patients with septic shock: effects on norepinephrine requirements, cardiopulmonary performance, and global oxygen transport.
Morelli, A, Lange, M, Ertmer, C, Broeking, K, Van Aken, H, Orecchioni, A, Rocco, M, Bachetoni, A, Traber, DL, Landoni, G, et al
Shock (Augusta, Ga.). 2007;(5):530-5
Abstract
Adenosine triphosphate-sensitive potassium channels are important regulators of arterial vascular smooth muscle tone and are implicated in the pathophysiology of catecholamine tachyphylaxis in septic shock. The present study was designed as a prospective, randomized, double-blinded, clinical pilot study to determine whether different doses of glibenclamide have any effects on norepinephrine requirements, cardiopulmonary hemodynamics, and global oxygen transport in patients with septic shock. We enrolled 30 patients with septic shock requiring invasive hemodynamic monitoring and norepinephrine infusion of 0.5 microg.kg-1.min-1 or greater to maintain MAP between 65 and 75 mmHg. In addition to standard therapy, patients were randomized to receive either 10, 20, or 30 mg of enteral glibenclamide. Systemic hemodynamics, global oxygen transport including arterial lactate concentrations, gas exchange, plasma glucose concentrations, and electrolytes were determined at baseline and after 3, 6, and 12 h after administration of the study drug. Glibenclamide decreased plasma glucose concentrations in a dose-dependent manner but failed to reduce norepinephrine requirements. None of the doses had any effects on cardiopulmonary hemodynamics, global oxygen transport, gas exchange, or electrolytes. These data suggest that oral glibenclamide in doses from 10 to 30 mg fails to counteract arterial hypotension and thus to reduce norepinephrine requirements in catecholamine-dependent human septic shock.