Respiratory Quotient (respiratory + quotient)

Distribution by Scientific Domains


Selected Abstracts


Low-fat oxidation may be a factor in obesity among men with schizophrenia

ACTA PSYCHIATRICA SCANDINAVICA, Issue 6 2009
J.-K. Sharpe
Objective:, Obesity associated with atypical antipsychotic medications is an important clinical issue for people with schizophrenia. The purpose of this project was to determine whether there were any differences in resting energy expenditure (REE) and respiratory quotient (RQ) between men with schizophrenia and controls. Method:, Thirty-one men with schizophrenia were individually matched for age and relative body weight with healthy, sedentary controls. Deuterium dilution was used to determine total body water and subsequently fat-free mass (FFM). Indirect calorimetry using a Deltatrac metabolic cart was used to determine REE and RQ. Results:, When corrected for FFM, there was no significant difference in REE between the groups. However, fasting RQ was significantly higher in the men with schizophrenia than the controls. Conclusion:, Men with schizophrenia oxidised proportionally less fat and more carbohydrate under resting conditions than healthy controls. These differences in substrate utilisation at rest may be an important consideration in obesity in this clinical group. [source]


Obesity and metabolic syndrome in histone demethylase JHDM2a-deficient mice

GENES TO CELLS, Issue 8 2009
Takeshi Inagaki
Histone H3 lysine 9 (H3K9) methylation is a crucial epigenetic mark of heterochromatin formation and transcriptional silencing. Recent studies demonstrated that most covalent histone lysine modifications are reversible and the jumonji C (JmjC)-domain-containing proteins have been shown to possess such demethylase activities. However, there is little information available on the biological roles of histone lysine demethylation in intact animal model systems. JHDM2A (JmjC-domain-containing histone demethylase 2A, also known as JMJD1A) catalyses removal of H3K9 mono- and dimethylation through iron and ,-ketoglutarate dependent oxidative reactions. Here, we demonstrate that JHDM2a also regulates metabolic genes related to energy homeostasis including anti-adipogenesis, regulation of fat storage, glucose transport and type 2 diabetes. Mice deficient in JHDM2a (JHDM2a,/,) develop adult onset obesity, hypertriglyceridemia, hypercholesterolemia, hyperinsulinemia and hyperleptinemia, which are hallmarks of metabolic syndrome. JHDM2a,/, mice furthermore exhibit fasted induced hypothermia indicating reduced energy expenditure and also have a higher respiratory quotient indicating less fat utilization for energy production. These observations may explain the obesity phenotype in these mice. Thus, H3K9 demethylase JHDM2a is a crucial regulator of genes involved in energy expenditure and fat storage, which suggests it is a previously unrecognized key regulator of obesity and metabolic syndrome. [source]


Modelling the respiration rate of fresh-cut Annurca apples to develop modified atmosphere packaging

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2009
Elena Torrieri
Summary In this work, the effect of temperature, oxygen, red coloration process and post-harvest storage time on the respiration rate of fresh-cut Annurca apples was studied to properly develop modified atmosphere packaging. Our results showed that the red coloration process and the post-harvest storage time did not affect the respiration rate or the respiratory quotient of fresh-cut Annurca apples in the range of temperature studied (5,20 °C). A Michaelis,Menten-type equation, with the model constants described by means of an Arrhenius-type relationship, was used for predicting respiration rate on varying the temperature and O2 concentration in the head space. The maximal respiration rate (mL kg h,1) (RRmax) and the O2% corresponding to values estimated at the reference temperature (12.5 °C), i.e. the average of the experimental temperature ranges, were, respectively, 6.77 ± 0.1 mL kg,1 h,1 and 0.68 ± 0.07% v/v, and the activation energy of the aerobic respiration rate of fresh-cut Annurca apples was estimated at 51 ± 1 kJ mol,1. The model works well to develop a modified atmosphere for fresh-cut Annurca apples. [source]


Long-term Infusion of Brain-Derived Neurotrophic Factor Reduces Food Intake and Body Weight via a Corticotrophin-Releasing Hormone Pathway in the Paraventricular Nucleus of the Hypothalamus

JOURNAL OF NEUROENDOCRINOLOGY, Issue 9 2010
M. Toriya
Brain-derived neurotrophic factor (BDNF) has been implicated in learning, depression and energy metabolism. However, the neuronal mechanisms underlying the effects of BDNF on energy metabolism remain unclear. The present study aimed to elucidate the neuronal pathways by which BDNF controls feeding behaviour and energy balance. Using an osmotic mini-pump, BDNF or control artificial cerebrospinal fluid was infused i.c.v. at the lateral ventricle or into the paraventricular nucleus of the hypothalamus (PVN) for 12 days. Intracerebroventricular BDNF up-regulated mRNA expression of corticotrophin-releasing hormone (CRH) and urocortin in the PVN. TrkB, the receptor for BDNF, was expressed in the PVN neurones, including those containing CRH. Both i.c.v. and intra-PVN-administered BDNF decreased food intake and body weight. These effects of BDNF on food intake and body weight were counteracted by the co-administration of ,-helical-CRH, an antagonist for the CRH and urocortin receptors CRH-R1/R2, and partly attenuated by a selective antagonist for CRH-R2 but not CRH-R1. Intracerebroventricular BDNF also decreased the subcutaneous and visceral fat mass, adipocyte size and serum triglyceride levels, which were all attenuated by ,-helical-CRH. Furthermore, BDNF decreased the respiratory quotient and raised rectal temperature, which were counteracted by ,-helical-CRH. These results indicate that the CRH-urocortin-CRH-R2 pathway in the PVN and connected areas mediates the long-term effects of BDNF to depress feeding and promote lipolysis. [source]


Effects of glucose, cellulose, and humic acids on soil microbial eco-physiology

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2004
Oliver Dilly
Abstract Microbial eco-physiology in soils is regulated by substrate quality of the organic matter. This regulation was studied for a forest and an agricultural soil by the combination of activity and biomass techniques. Soil respiration was stimulated by the substrate quality in the order, humic acid < cellulose < glucose over 20 days. Concurrently, substrate addition increased the respiratory quotient (RQ), defined as the ratio of mol CO2 evolution per mol O2 uptake. Anabolic processes were mainly induced by glucose addition. Soil preconditioned with glucose showed a decrease in the RQ value during glucose-induced microbial growth in comparison to non-amended control. The decrease in the RQ value induced by preconditioning with cellulose and humic acid was lower. Glucose, cellulose, and humic acid addition modified the microbial biomass as estimated by fumigation-extraction (FE), substrate-induced respiration (SIR), and ATP content. Since each biomass estimate refers to specific microbial components, shifts in microbial eco-physiology and community structure induced by substrate quality were reflected by SIR : FE and SIR : ATP ratios. The active and glucose-responsive biomass in the forest soil which was earlier suggested as being dominated by K-strategists was increased in the order, humic acid < cellulose < glucose. Einfluss von Zugaben von Glucose-, Cellulose und Huminsäuren auf die mikrobielle Ökophysiologie im Boden Die Ökophysiologie der mikrobiellen Gemeinschaften in Böden ist abhängig von der Substratqualität der organischen Substanz. Dies wurde nach Zugabe von Substraten für zwei Böden, einer unter Buchenwald und einer unter Acker, anhand einer Kombination von biochemischen und physiologischen Aktivitäts- und Biomassetechniken analysiert. Die Substratzugabe erhöhte die Bodenatmung über 20 Tage hinweg in der Reihenfolge Huminsäuren < Cellulose < Glucose. Gleichzeitig wurde auch der respiratorische Quotient (RQ), definiert als das Verhältnis von CO2 -Freisetzung zu O2 -Aufnahme, durch die Substratzugabe erhöht und anabolische Prozesse induziert. Das mikrobielle Wachstum wurde in erster Linie durch Glucose stimuliert. Der mit Glucose als Substrat versetzte Boden zeigte eine Abnahme des RQ während eines glucose-induzierten Wachstums im Vergleich zur Kontrolle. Eine solche Abnahme war bei der Huminsäure- und Cellulosebehandlung geringer. Die Zugabe von Glucose, Cellulose und Huminsäuren veränderte schließlich die mikrobielle Biomasse, welche mittels Fumigation-Extraktion, substratinduzierter Atmung und ATP-Gehalt ermittelt wurde. Da jede Technik spezifische mikrobielle Komponenten erfasst, wurden Veränderungen in der mikrobiellen Ökophysiologie und der Struktur der mikrobiellen Gemeinschaften durch die Substrate induziert, die in dem SIR:FE- und SIR:ATP-Verhältnis erkennbar waren. Die aktive und glucoseaktivierbare Biomasse in einem von K-Strategen dominierten Waldboden nahm von Huminsäure-, über Cellulose- und Glucosezugabe hin zu. [source]


Metabolic effects in neonates receiving intravenous medium-chain triglycerides

ACTA PAEDIATRICA, Issue 2 2002
G Angsten
The effects of two lipid emulsions, one with 50% each of medium-chain and long-chain triglycerides, and a long-chain triglycerides lipid emulsion as a control, were evaluated for lipid and carnitine metabolism and respiratory quotient when given to neonates after major surgery during a short period of total parenteral nutrition. Each group included 10 neonates, and all tolerated the total parenteral nutrition well. The relative contents of linoleic acid and ,-linolenic acid increased in all lipid esters in plasma and adipose tissue in both groups, indicating that the content of these fatty acids is sufficient even in the medium-chain triglycerides emulsion. The serum concentration of ketones was within normal limits. Free fatty acids in plasma did not increase in either group. The total plasma carnitine concentration decreased in both groups but the distribution of free carnitine and acylcarnitine did not change. The total muscle carnitine did not change significantly but the ratio of acylcarnitine to free carnitine tended to increase in muscle in the treatment group, probably an effect of the medium-chain triglyceride supplementation. Conclusions: The two groups displayed the same fatty acid pattern in plasma and adipose tissue and the same respiratory quotient during the treatment period. Regarding carnitine status, essentially the same changes were seen in the two groups. However, discrete changes were seen in muscle tissue in the treatment group. [source]


Effects of augmentation of coarse particulate organic matter on metabolism and nutrient retention in hyporheic sediments

FRESHWATER BIOLOGY, Issue 10 2002
C. L. Crenshaw
SUMMARY 1.,Metabolic and biogeochemical processes in hyporheic zones may depend on inputs of coarse particulate organic matter. Our research focused on how differing quantity and quality of organic matter affects metabolism and nutrient retention in the hyporheic zone of a first-order Appalachian stream. 2.,Sixteen plots were established on a tributary of Hugh White Creek, NC, U.S.A. Sediment was extracted and treated with leaves, wood, plastic strips or remained unamended. Following treatment, sediment was returned to the stream and, approximately 3 months later, samples were removed from each plot. 3.,Aerobic and anaerobic metabolism were measured as the change in O2 and CO2 in recirculating microcosms. At the same time, we monitored other possible terminal electron accepting processes and changes in nutrient concentrations. Aerobic metabolism was low in all treatments and respiratory quotients calculated for all treatments indicated that metabolism was dominated by anaerobic processes. 4.,Rates of anaerobic respiration and total (combined aerobic and anaerobic) respiration were significantly greater (P < 0.05) in plots treated with leaf organic matter compared to controls. 5.,Addition of leaves, which had a low C:N ratio, stimulated respiration in hyporheic sediments. Anaerobic processes dominated metabolism in both control and amended sediments. Enhanced metabolic rates increased retention of many solutes, indicating that energy flow and nutrient dynamics in the subsurface of streams may depend upon the quantity and quality of imported carbon. [source]