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Metabolic Measurements (metabolic + measurement)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Genome-scale modeling of Synechocystis sp.

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2009
PCC 680, prediction of pathway insertion
Abstract BACKGROUND: Cyanobacterium Synechocystis sp. PCC 6803 has been used widely as a model system for the study of photosynthetic organisms and higher plants. The aim of this work was to integrate the genomic information, biochemistry and physiological information available for Synechocystis sp. PCC 6803 to reconstruct a metabolic network for system biology investigations. RESULTS: A genome-scale Synechocystis sp. PCC 6803 metabolic network, including 633 genes, 704 metabolites and 831 metabolic reactions, was reconstructed for the study of optimal Synechocystis growth, network capacity and functions. Heterotrophic, photoautotrophic and mixotrophic growth conditions were simulated. The Synechocystis model was used for in silico predictions for the insertion of ethanol fermentation pathway, which is a novel approach for bioenergy and biofuels production developed in the authors' laboratory. Simulations of Synechocystis cell growth and ethanol production were compared with actual metabolic measurements which showed a satisfactory agreement. CONCLUSION: The Synechocystis metabolic network developed in this study is the first genome-scale mathematical model for photosynthetic organisms. The model may be used not only in global understanding of cellular metabolism and photosynthesis, but also in designing metabolic engineering strategies for desirable bio-products. Copyright © 2008 Society of Chemical Industry [source]

Reproducibility assessment of metabolic variables characterizing muscle energetics in Vivo: A 31P-MRS study

MAGNETIC RESONANCE IN MEDICINE, Issue 4 2009
Gwenael Layec
Abstract The purpose of the present study was to assess the reliability of metabolic parameters measured using 31P magnetic resonance spectroscopy (31P MRS) during two standardized rest-exercise-recovery protocols. Twelve healthy subjects performed the standardized protocols at two different intensities; i.e., a moderate intensity (MOD) repeated over a two-month period and heavy intensity (HEAVY) repeated over a year's time. Test-retest reliability was analyzed using coefficient of variation (CV), limits of agreement (LOA), and intraclass correlation coefficients (ICC). During exercise and recovery periods, most of the metabolic parameters exhibited a good reliability. The CVs of individual concentration of phosphocreatine ([PCr]), concentration of adenosine diphosphate ([ADP]), and pH values recorded at end of the HEAVY exercise were lower than 15%. The CV calculated for the rate of PCr resynthesis and the maximal oxidative capacity were less than 13% during the HEAVY protocol. Inferred parameters such as oxidative and total adenosine triphosphate (ATP) production rates exhibited a good reliability (ICC , 0.7; CV < 15% during the HEAVY protocol). Our results demonstrated that measurement error using 31P-MRS during a standardized exercise was low and that biological variability accounted for the vast majority of the measurement variability. In addition, the corresponding metabolic measurements can reliably be used for longitudinal studies performed even over a long period of time. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source]

Low-carbohydrate (low & high-fat) versus high-carbohydrate low-fat diets in the treatment of obesity in adolescents

ACTA PAEDIATRICA, Issue 2 2009
S Demol
Abstract Aim: To compare the impact of low-carbohydrate diets of different fat content to high-carbohydrate low-fat diet on weight and metabolic parameters in obese adolescents. Methods: Fifty-five patients aged 12,18 years with a body mass index (BMI) above the 95th percentile were randomly allocated to one of three isoenergetic diet regimens. Anthropometric and metabolic measurements were taken after overnight fast, at baseline, after the 12-week intervention and after nine month of follow-up. Results: No significant differences were found among the groups in changes in BMI, BMI-percentile, fat percentage, or metabolic markers at the end of the intervention and at the end of follow-up. Insulin level and homeostasis model assessment (HOMA) level decreased significantly at both time points only in the two low carbohydrate diet groups. Conclusion: All diet regimens are associated with a significant reduction in BMI and improvement of some metabolic parameters in obese adolescents. Low-carbohydrate diets apparently have no advantage over high-carbohydrate low-fat diets. The significant drop in insulin level and HOMA in the low carbohydrate diet groups is noteworthy given the increasing frequency of type-2 diabetes as part of metabolic syndrome in children and youth. The impact of low carbohydrate diets in obese and insulin-resistant youth warrants further investigation. [source]

Relationship between arterial baroreflex sensitivity and exercise capacity in patients with acute myocardial infarction

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 1 2010
Fumio Yuasa
Summary To investigate the relationship between arterial baroreflex sensitivity (BRS) and exercise capacity, we examined arterial BRS and its relation to exercise capacity during upright bicycle exercise in 40 uncomplicated patients with acute myocardial infarction. Arterial BRS was measured 3 weeks (20 ± 5 days) after acute myocardial infarction and assessed by calculating the regression line relating phenylephrine-induced increases in systolic blood pressure to the attendant changes in the R,R interval. All patients underwent graded symptom-limited bicycle exercise with direct measurements of hemodynamic and metabolic measurements. In all patients, the average arterial BRS was 5·6 ± 2·6 ms mmHg,1. There were no significant correlations between arterial BRS and hemodynamic measurements at rest. However, arterial BRS was negatively related to systemic vascular resistance at peak exercise (r = ,0·60, P = 0·0001) and percent change increase in systemic vascular resistance from rest to peak exercise (r = ,0·45, P = 0·003), whereas arterial BRS was positively related to cardiac output (r = ,0·48, P = 0·002) and stroke volume at peak exercise (r = 0·42, P = 0·007), and percent change increase in cardiac output (r = ,0·55, P = 0·0002) and stroke volume from rest to peak exercise (r = 0·41, P = 0·008). Furthermore, arterial BRS had modest but significant correlations with peak oxygen consumption (r = ,0·48, P = 0·002) and exercise duration (r = 0·35, P = 0·029), indicating that patients with better arterial BRS have better exercise capacity in patients with acute myocardial infarction. These results suggest that arterial BRS was linked to central and peripheral hemodynamic responses to exercise and hence, contributed to exercise capacity after acute myocardial infraction. [source]