scholarly journals Measuring metabolic rate in single flies during sleep and waking states

2021 ◽  
Author(s):  
Elizabeth B Brown ◽  
Jaco Klok ◽  
Alex C Keene
Keyword(s):  
Metabolic Rate ◽  
Indirect Calorimetry ◽  
Genetic Model ◽  
Brain Activity ◽  
Physiological State ◽  
Whole Body ◽  
Genetic Studies ◽  
Simultaneous Acquisition ◽  
Co2 Output ◽  
Highly Sensitive

Drosophila melanogaster is a leading genetic model for studying the neural regulation of sleep. Sleep is associated with changes in behavior and physiological state that are largely conserved across species. The investigation of sleep in flies has predominantly focused on behavioral readouts of sleep because physiological measurements, including changes in brain activity and metabolic rate are less accessible. We have previously used stop-flow indirect calorimetry to measure whole body metabolic rate in single flies and have shown that in flies, like mammals, metabolic rate is reduced during sleep. Here, we describe a modified version of this system that allows for efficient and highly sensitive acquisition of CO2 output from single flies. We also describe a modification that allows for simultaneous acquisition of CO2 and O2 levels, providing a respiratory quotient that quantifies how metabolic stores are utilized. Finally, we show that sleep-dependent changes in metabolic rate are diminished in aging flies, supporting the notion that sleep quality is reduced as flies age. Taken together, the use of indirect calorimetry provides a physiological measure of sleep with broad applications to genetic studies in flies.

Metabolic rate and fuel utilization during sleep assessed by whole-body indirect calorimetry

Metabolism ◽  
2009 ◽  
Vol 58 (7) ◽  
pp. 920-926 ◽  
Author(s):  
Yasuko Katayose ◽  
Mami Tasaki ◽  
Hitomi Ogata ◽  
Yoshio Nakata ◽  
Kumpei Tokuyama ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Indirect Calorimetry ◽  
Whole Body ◽  
Fuel Utilization

scholarly journals Body mass-specific Na+-K+-ATPase activity in the medullary thick ascending limb: implications for species-dependent urine concentrating mechanisms

2018 ◽  
Vol 314 (4) ◽  
pp. R563-R573 ◽  
Author(s):  
Mun Aw ◽  
Tamara M. Armstrong ◽  
C. Michele Nawata ◽  
Sarah N. Bodine ◽  
Jeeeun J. Oh ◽  
...  
Keyword(s):  
Protein Expression ◽  
Atpase Activity ◽  
Metabolic Rate ◽  
Body Mass ◽  
Whole Body ◽  
Osmotic Gradient ◽  
Thick Ascending Limb ◽  
Rat Strains ◽  
Kangaroo Rat ◽  
Gene And Protein Expression

In general, the mammalian whole body mass-specific metabolic rate correlates positively with maximal urine concentration (Umax) irrespective of whether or not the species have adapted to arid or mesic habitat. Accordingly, we hypothesized that the thick ascending limb (TAL) of a rodent with markedly higher whole body mass-specific metabolism than rat exhibits a substantially higher TAL metabolic rate as estimated by Na+-K+-ATPase activity and Na+-K+-ATPase α1-gene and protein expression. The kangaroo rat inner stripe of the outer medulla exhibits significantly higher mean Na+-K+-ATPase activity (~70%) compared with two rat strains (Sprague-Dawley and Munich-Wistar), extending prior studies showing rat activity exceeds rabbit. Furthermore, higher expression of Na+-K+-ATPase α1-protein (~4- to 6-fold) and mRNA (~13-fold) and higher TAL mitochondrial volume density (~20%) occur in the kangaroo rat compared with both rat strains. Rat TAL Na+-K+-ATPase α1-protein expression is relatively unaffected by body hydration status or, shown previously, by dietary Na+, arguing against confounding effects from two unavoidably dissimilar diets: grain-based diet without water (kangaroo rat) or grain-based diet with water (rat). We conclude that higher TAL Na+-K+-ATPase activity contributes to relationships between whole body mass-specific metabolic rate and high Umax. More vigorous TAL Na+-K+-ATPase activity in kangaroo rat than rat may contribute to its steeper Na+ and urea axial concentration gradients, adding support to a revised model of the urine concentrating mechanism, which hypothesizes a leading role for vigorous active transport of NaCl, rather than countercurrent multiplication, in generating the outer medullary axial osmotic gradient.

Analysis of oxygen delivery and uptake relationships in the Krogh tissue model

1989 ◽  
Vol 67 (3) ◽  
pp. 1234-1244 ◽  
Author(s):  
P. T. Schumacker ◽  
R. W. Samsel
Keyword(s):  
Blood Flow ◽  
Critical Point ◽  
Real Data ◽  
Whole Body ◽  
O2 Uptake ◽  
Highly Sensitive ◽  
O2 Extraction ◽  
O2 Supply ◽  
Experimental Findings ◽  
O2 Delivery

Normally, tissue O2 uptake (VO2) is set by metabolic activity rather than O2 delivery (QO2 = blood flow X arterial O2 content). However, when QO2 is reduced below a critical level, VO2 becomes limited by O2 supply. Experiments have shown that a similar critical QO2 exists, regardless of whether O2 supply is reduced by progressive anemia, hypoxemia, or reduction in blood flow. This appears inconsistent with the hypothesis that O2 supply limitation must occur by diffusion limitation, since very different mixed venous PO2 values have been seen at the critical point with hypoxic vs. anemic hypoxia. The present study sought to begin clarifying this paradox by studying the theoretical relationship between tissue O2 supply and uptake in the Krogh tissue cylinder model. Steady-state O2 uptake was computed as O2 delivery to tissue representative of whole body was gradually lowered by anemic, hypoxic, or stagnant hypoxia. As diffusion began to limit uptake, the fall in VO2 was computed numerically, yielding a relationship between QO2 and VO2 in both supply-independent and O2 supply-dependent regions. This analysis predicted a similar biphasic relationship between QO2 and VO2 and a linear fall in VO2 at O2 deliveries below a critical point for all three forms of hypoxia, as long as intercapillary distances were less than or equal to 80 microns. However, the analysis also predicted that O2 extraction at the critical point should exceed 90%, whereas real tissues typically extract only 65–75% at that point. When intercapillary distances were larger than approximately 80 microns, critical O2 extraction ratios in the range of 65–75% could be predicted, but the critical point became highly sensitive to the type of hypoxia imposed, contrary to experimental findings. Predicted gas exchange in accord with real data could only be simulated when a postulated 30% functional peripheral O2 shunt (arterial admixture) was combined with a tissue composed of Krogh cylinders with intercapillary distances of less than or equal to 80 microns. The unrealistic efficacy of tissue O2 extraction predicted by the Krogh model (in the absence of postulated shunt) may be a consequence of the assumed homogeneity of tissues, because real tissues exhibit many forms of heterogeneity among capillary units. Alternatively, the failure of the original Krogh model to fully predict tissue O2 supply dependency may arise from basic limitations in the assumptions of that model.

Heart rate recording method validated by whole body indirect calorimetry in 10-yr-old children

1996 ◽  
Vol 81 (3) ◽  
pp. 1169-1173 ◽  
Author(s):  
A. Bitar ◽  
M. Vermorel ◽  
N. Fellmann ◽  
M. Bedu ◽  
A. Chamoux ◽  
...  
Keyword(s):  
Heart Rate ◽  
Indirect Calorimetry ◽  
Laboratory Tests ◽  
Prediction Equation ◽  
Whole Body ◽  
Healthy Children ◽  
Recording Method ◽  
Mean Differences ◽  
Best Fit ◽  
Heart Rate Recording

The aim of the study was to validate the heart rate (HR) recording method against whole body indirect calorimetry in prepubertal children. Nineteen 10.5-yr-old healthy children (10 boys, 9 girls) participated in this study. HR and energy expenditure (EE) were recorded through laboratory tests. Individual relationships between HR and EE were computed (equation established in laboratory). Several models were tested and validated from 24-h measurements of EE and HR by whole body indirect calorimetry. The best fit was obtained with individual polynomial relationships. Mean differences between predicted (equation established in laboratory) and measured total daily EE averaged 7.6 +/- 20.1%. The causes of the differences and the means of improving the accuracy of the prediction equation are discussed.

scholarly journals Why most Principal Component Analyses (PCA) in population genetic studies are wrong

2021 ◽  
Author(s):  
Eran Elhaik
Keyword(s):  
Population Genetics ◽  
Population Genetic ◽  
Genetic Model ◽  
Principal Component ◽  
Population Data ◽  
Test Cases ◽  
Validity Of Results ◽  
Genetic Studies ◽  
Minimal Loss ◽  
Admixture Population

Principal Component Analysis (PCA) is a multivariate analysis that allows reduction of the complexity of datasets while preserving data's covariance and visualizing the information on colorful scatterplots, ideally with only a minimal loss of information. PCA applications are extensively used as the foremost analyses in population genetics and related fields (e.g., animal and plant or medical genetics), implemented in well-cited packages like EIGENSOFT and PLINK. PCA outcomes are used to shape study design, identify and characterize individuals and populations, and draw historical and ethnobiological conclusions on origins, evolution, whereabouts, and relatedness. The replicability crisis in science has prompted us to evaluate whether PCA results are reliable, robust, and replicable. We employed an intuitive color-based model alongside human population data for eleven common test cases. We demonstrate that PCA results are artifacts of the data and that they can be easily manipulated to generate desired outcomes. PCA results may not be reliable, robust, or replicable as the field assumes. Our findings raise concerns on the validity of results reported in the literature of population genetics and related fields that place a disproportionate reliance upon PCA outcomes and the insights derived from them. We conclude that PCA may have a biasing role in genetic investigations. An alternative mixed-admixture population genetic model is discussed.

scholarly journals Cardiac Troponins: Analytical Characteristics and Diagnostic Capabilities of Modern (High-sensitive) Determination Methods

2021 ◽  
Author(s):  
Aleksey Michailovich Chaulin ◽  
Duplyakov V Dmitry
Keyword(s):  
Myocardial Infarction ◽  
Physiological State ◽  
Economic Damage ◽  
Routine Practice ◽  
Coronary Syndrome ◽  
Highly Sensitive ◽  
Sensitive Determination ◽  
Determination Methods ◽  
Cardiac Troponins

Cardiovascular diseases have a leading role in terms of morbidity, mortality, and disability of the population, causing significant socio-economic damage to all countries of the world. This circumstance requires researchers to constantly seek for new biomarkers and improve methods for determining existing biomarkers, and search for new therapeutic targets to improve diagnostic and treatment strategies. Recently, there have been some important changes in laboratory diagnostics of patients with acute coronary syndrome, due to the introduction into the routine practice of new high and ultrasensitive methods for the determination of biomarkers of injury, specific to cardiac muscle tissue, namely cardiac troponins. A key advantage of highly sensitive immunochemical assays is the ability to detect cardiac troponins in the early stages of myocardial infarction. This allows making the optimal decision on the early choice and conduct of reperfusion therapy, which significantly improves the further prognosis of patients. Among the most significant generally recognised disadvantages of highly sensitive determination methods are low specificity and a huge variety of troponin immunoassays. The decrease in specificity is reflected in the fact that cardiac troponins are no longer considered the “gold standard” of diagnosis related to Acute Myocardial Infarction (AMI) (irreversible ischaemic damage to cardiomyocytes). As a result, any damage to the myocardium, even insignificant and reversible under physiological state (physical activity, stress) and several pathological conditions, can lead to an increase in serum levels of cardiac troponins and affect the accuracy of the diagnosis. Each method for the determination of cardiac troponins, among the existing wide variety of troponin immunoassays, possesses different analytical characteristics, and detects different concentrations of troponins in the same patient. This article provides a view of current data on the biology of cardiac troponins, and defines the analytical characteristics of new high-sensitive methods for the determination of cardiac troponins.

Maturation of baseline breathing and of hypercapnic and hypoxic ventilatory responses in newborn mice

2001 ◽  
Vol 281 (5) ◽  
pp. R1746-R1753 ◽  
Author(s):  
Sylvain Renolleau ◽  
Stéphane Dauger ◽  
Fanny Autret ◽  
Guy Vardon ◽  
Claude Gaultier ◽  
...  
Keyword(s):  
Cesarean Section ◽  
Tidal Volume ◽  
Mammalian Species ◽  
Whole Body ◽  
Body Plethysmography ◽  
Genetic Studies ◽  
Newborn Mice ◽  
Ventilatory Responses ◽  
Neuronal Mechanisms ◽  
Whole Body Plethysmography

Breathing during the first postnatal hours has not been examined in mice, the preferred mammalian species for genetic studies. We used whole body plethysmography to measure ventilation (V˙e), breath duration (TTOT), and tidal volume (Vt) in mice delivered vaginally (VD) or by cesarean section (CS). In experiment 1, 101 VD and 100 CS pups aged 1, 6, 12, 24, or 48 h were exposed to 8% CO2 or 10% O2for 90 s. In experiment 2, 31 VD pups aged 1, 12, or 24 h were exposed to 10% O2 for 5 min. Baseline breathing maturation was delayed in CS pups, but V˙eresponses to hypercapnia and hypoxia were not significantly different between VD and CS pups [at postnatal age of 1 h (H1): 48 ± 44 and 18 ± 32%, respectively, in VD and CS pups combined]. TheV˙e increase induced by hypoxia was greater at H12 (46 ± 27%) because of TTOT response maturation. At all ages, hypoxic decline was ascribable mainly to a Vtdecrease, and posthypoxic decline was ascribable to a TTOTincrease with apneas, suggesting different underlying neuronal mechanisms.

scholarly journals Thermic effect of glucose and amino acids in man studied by direct and indirect calorimetry

1974 ◽  
Vol 31 (3) ◽  
pp. 343-349 ◽  
Author(s):  
Ph. Pittet ◽  
P. H. Gygax ◽  
E. Jéquier
Keyword(s):  
Amino Acids ◽  
Energy Balance ◽  
Metabolic Rate ◽  
Heat Production ◽  
Indirect Calorimetry ◽  
Control Period ◽  
Essential Amino Acids ◽  
Specific Dynamic Action ◽  
Heat Losses ◽  
Thermic Effect

1. In order to reinvestigate the classical concept of specific dynamic action of food, the thermic effect of ingested glucose (50 g) or essential amino acids (50 g) or both was measured in seven healthy male subjects dressed in shorts, by using both direct and indirect calorimetry simultaneously. Experiments were performed under conditions of thermal comfort at 28°.2. Energy ‘balance’ (heat production minus heat losses) was negative during the control period (mean heat deficit: −16.0 ± 0.8 kJ/m2 per h.3. Metabolic rate increased 13.6 ± 1.8% after the glucose load, 17.2 ± 1.4% after amino acids, and 17.3 ± 2.9% after both glucose and amino acids: thus there was no additive thermic effect when both nutrients were given together.4. In contrast to the metabolic rate, heat losses were not significantly altered after nutrient ingestion; consequently, the energy ‘balance’ became rapidly positive.5. These results show that: (a) the food-induced thermogenesis, for a moderate energy intake, is less dependent on the nature of the nutrients than was classically admitted; (b) this increased heat production mainly induces changes in heat storage rather than in heat losses during the first hours following ingestion of a meal.

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