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PubMed1975

A comparison of the energy metabolism of two breeds of hens and their cross using respiration calorimetry.

1. The maintenance energy requirement of the Black Australorp, White Leghorn and Black Australorp times White Leghorn hen was 911, 765 and 885 kJ/d respectively and availability of metabolisable energy of the diet was 79, 84 and 92%. 2. Heat production, after 30 h of starvation, was 311, 395 and 387 kJ/kg W0-75/d for the Australorp, Leghorn and crossbred, respectively. 3. It was calculated that availability of metabolisable energy was 51% for protein and 96% for fat retention. 4. Water consumption was significantly higher for the Black Australorp at the mean level of food intake for all hens, and increased more rapidly per unit intake than was observed for the other two breeds.

Animal Feed↗
PubMed1989

Thermodynamics of B-Z transition of poly[d(G-C)] in a water-ethanol solution. The "tie calorimetry".

Poly[d(G-C)] in a 55% ethanol solution undergoes a transition from the Z form to the B form when the temperature is increased from 20 degrees to 50 degrees C. The enthalpy of the transition, delta HBA = -1.4 kcal/mol, has been determined with a "tie" polyamine which stabilizes the Z conformation. This value has been shown to be practically independent of ionic strength within the range of 5 X 10(-4) M - 2 X 10(-3) M NaCl.

Calorimetry↗
PubMed2004

Inhibition of beta-amylase activity by calcium, magnesium and zinc ions determined by spectrophotometry and isothermal titration calorimetry.

The inhibition effect of metal ions on beta amylase activity was studied. The inhibitor-binding constant (Ki) was determined by spectrophotometric and isothermal titration calorimetric (ITC) methods. The binding of calcium, magnesium and zinc ion as inhibitors at the active site of barley beta amylase was studied at pH = 4.8 (sodium acetate 16 mM) and T = 300K. The Ki and enthalpy of binding for calcium (13.4, 13.1 mM and -14.3 kJ/mol), magnesium (18.6, 17.8mM and -17.7 kJ/mol) and zinc (17.5, 17.7 mM and -20.0 kJ/mol) were found by spectrophotometric and ITC methods respectively.

Calcium↗
PubMed1992

Calorimetry: a new quantitative in vitro method in cell toxicology. A dose/effect study of alveolar macrophages exposed to particles.

A short-term toxicological test has been developed using a calorimetric method. The metabolic activity, observed as the heat exchange rate, was monitored from alveolar rabbit macrophages in monolayers exposed to different metal and non-metal particles. Calorimetric activity indices and viability indices were introduced, from which toxic effects could be assessed. Manganese dioxide particles were found to be cytotoxic. In contrast, titanium dioxide particles seemed to be harmless. The results were in accordance with the cell survival found by use of a fluorescein ester staining method and measured by an image analyzer. Toxic effects from quartz in the form of increased metabolic activity of exposed cells could be detected by the calorimeter in contradiction to the use of the image analyzer. This latter result supports the hypothesis that silica particles cause chronic modification of the macrophage function and that this change in the alveolar macrophage function may be the first of a series of processes leading to pulmonary fibrosis.

Animals↗
PubMed1987

Energy requirements and energy expenditure of lean and overweight women, measured by indirect calorimetry.

To estimate the energy requirement of lean and overweight women, 29 lean (body weight, 59 +/- 1 kg; means +/- SEM) and 18 overweight (94 +/- 5 kg) women consumed a weight-maintenance diet for 8 d. The final 80 h were spent in a whole-body indirect calorimeter. Actual metabolizable energy intake (ME) was measured by analyzing food, feces, and urine. Mean ME was 8.88 +/- 0.13 MJ/d (2123 +/- 30 kcal/d) (lean) and 10.12 +/- 0.29 MJ/d (2419 +/- 70 kcal/d) (overweight). Mean 24-h energy expenditure (24hEE) of the lean (8.58 +/- 0.13 MJ or 2052 +/- 32 kcal) was lower than that of the overweight (10.70 +/- 0.45 MJ or 2558 +/- 108 kcal; p less than 0.001) women. Energy balance was close to zero in both groups. Therefore, 24hEE was used as an estimation of energy requirement. Multiple-regression analysis showed body weight to be the best single predictor of 24hEE. Our data may be useful for prediction of energy requirements of women (aged 20-50 yr) in normal life.

Adult↗
PubMed1988

Estimation of energy expenditure, net carbohydrate utilization, and net fat oxidation and synthesis by indirect calorimetry: evaluation of errors with special reference to the detailed composition of fuels.

Sources of error in the interpretation of respiratory data are evaluated and reviewed with special reference to the detailed composition of foods. Estimates of fuel utilization or synthesis are 12-fold more sensitive to errors in the nonprotein respiratory quotient than is the heat equivalent of oxygen. Estimates of protein oxidation from nitrogen excretion can be in error from +14 to -39% of the true value. Heat equivalents of oxygen, respiratory quotients, and urinary nitrogen-to-oxygen conversion ratios are considered for 60 artificial and 101 conventional food proteins, 36 artificial and 125 conventional food fats, and the different carbohydrates contained in these foods. It is concluded that there is considerable uncertainty when the mix of fuels utilized is assessed accurately. Accuracy is best within 5% of the true values. This analysis is completed with descriptions of some physiological sources of error in an appendix.

Algorithms↗
PubMed1993

In vivo measurement of changes in body composition: description of methods and their validation against 12-d continuous whole-body calorimetry.

The accuracy of a variety of in vivo body-composition techniques (densitometry, total body water, skinfold thicknesses, whole-body impedance and resistance, body mass index, and two three-compartment models) was assessed by comparison with fat balance. Three subjects were overfed and three underfed while confined to a 30-m3 whole-body calorimeter continuously for 12 d. Mean weight changes were +2.90 kg during overfeeding and -3.47 kg during underfeeding. The change in fat mass accounted for 37.1% during overfeeding and 59.3% during underfeeding. In comparison with energy and nitrogen balance, a three-compartment model yielded the least bias and greatest precision. The smallest change in fat mass that can be measured by such a method in an individual subject is 1.54 kg (2 SD). Of the prediction techniques considered, skinfold thicknesses or the body-mass-index formula appear to be more precise than estimates based on resistance or impedance.

Adolescent↗
PubMed1995

Twenty-four-hour energy expenditure and its components in prepubertal children as determined by whole-body indirect calorimetry and compared with young adults.

The aim of the present study was to compare total daily and circadian variations of energy expenditure (EE) in 21 prepubescent 10-y-old children (12 boys and 9 girls) and 18 23-y-old adults (9 men and 9 women) under the same conditions by using two large calorimetric chambers. The volunteers followed similar activity programs with four periods of exercise on a cyclergometer. Total daily and sleeping EE adjusted for differences in fat-free mass (FFM) and age were significantly higher in children than in adults by 35% and 27%, respectively (P < 0.001). EE during sleep decreased by 2% per hour in both age groups. Heart rate was significantly higher in girls than in boys. The energy cost of cycling, adjusted for differences in FFM and external mechanical power, was not significantly different in children and adults. The differences in EE between children and adults may partly result from a higher proportion of internal organs in the FFM.

Adult↗
PubMed1999

Variations and determinants of energy expenditure as measured by whole-body indirect calorimetry during puberty and adolescence.

BACKGROUND: Adolescence is characterized by rapid anatomic, physiologic, and behavioral alterations expected to induce changes in metabolic rate. OBJECTIVE: The aim of the present study was to investigate variations in daily energy expenditure (DEE) and its main components during adolescence and to quantify their significant determinants. DESIGN: Eighty-three children and adolescents (44 boys and 39 girls aged 10-16 y) participated in this cross-sectional study. Tanner stages ranged from 1 to 5. Body composition was assessed by both the skinfold-thickness method and bioimpedance analysis. Energy expenditure (EE) was determined continuously over 24 h by using 2 whole-body calorimeters. The subjects followed a standardized activity program that included four 15-min periods of exercise on a cycle ergometer. RESULTS: Body composition, DEE, sleeping EE (SEE), resting EE, and EE during meals, miscellaneous activities, and physical exercise varied significantly with sex and stage of puberty. The DEE of boys and girls averaged 8.22 and 7.60 MJ in prepubertal children, 11.35 and 9.10 MJ in pubertal children, and 11.73 and 9.68 MJ in postpubertal adolescents, respectively. The significant determinants of DEE and SEE, respectively, were fat-free mass (r2 = 0.842 and 0.826), sex (r2 = 0.017 and 0.022), and season (r2 = 0.021 and 0.011). Stage of puberty and fat mass were not significant factors. DEE and SEE adjusted for fat-free mass were on average 5% higher in boys than in girls and 6% higher in spring than in autumn. CONCLUSIONS: The DEE of adolescents measured under standardized conditions varied with sex, body composition, and season, but not with stage of puberty. These variables could be predicted accurately from fat-free mass, sex, and season.

Adolescent↗
PubMed1995

Comparison between oxygen consumption calculated by Fick's principle using a continuous thermodilution technique and measured by indirect calorimetry.

We calculated oxygen consumption by the reverse Fick principle (cVO2) using cardiac output measured with a new technique of continuous thermal dilution and compared these values with measurements made at the same time using a gas exchange method (mVO2). We studied nine patients in a stable condition after cardiac surgery. In each patient six successive measurements of continuous cardiac output and mVO2 were made over 5 min at 10-min intervals. The mean difference between the estimates (mVO2-cVO2) was 15 ml min-1 m2 (95% confidence limits, -3 to 33 ml min-1 m2). The relative error of each method was 5% and 4% (continuous cardiac output and gas exchange methods, respectively). Calculation of VO2 using the new cardiac output technology had good repeatability compared with direct measurement, probably because of the high precision of measurement of cardiac output.

Aged↗
PubMed2002

Cryopreservation of equine sperm: optimal cooling rates in the presence and absence of cryoprotective agents determined using differential scanning calorimetry.

Optimization of equine sperm cryopreservation protocols requires an understanding of the water permeability characteristics and volumetric shrinkage response during freezing. A cell-shape-independent differential scanning calorimeter (DSC) technique was used to measure the volumetric shrinkage during freezing of equine sperm suspensions at cooling rates of 5 degrees C/min and 20 degrees C/min in the presence and absence of cryoprotective agents (CPAs), i.e., in the Kenney extender and in the lactose-EDTA extender, respectively. The equine sperm was modeled as a cylinder of length 36.5 microm and a radius of 0.66 microm with an osmotically inactive cell volume (V(b)) of 0.6V(o), where V(o) is the isotonic cell volume. Sperm samples were collected using water-insoluble Vaseline in the artificial vagina and slow cooled at < or = 0.3 degrees C/min in an Equitainer-I from 37 degrees C to 4 degrees C. By fitting a model of water transport to the experimentally obtained DSC volumetric shrinkage data, the best-fit membrane permeability parameters (L(pg) and E(Lp)) were determined. The combined best-fit parameters of water transport (at both 5 degrees C/min and 20 degrees C/min) in Kenney extender (absence of CPAs) are L(pg) = 0.02 microm min(-1) atm(-1) and E(Lp) = 32.7 kcal/mol with a goodness-of-fit parameter R(2) = 0.96, and the best-fit parameters in the lactose-EDTA extender (the CPA medium) are L(pg)[cpa] = 0.008 microm min(-1) atm(-1) and E(Lp)[cpa] = 12.1 kcal/mol with R(2) = 0.97. These parameters suggest that the optimal cooling rate for equine sperm is approximately 29 degrees C/min and is approximately 60 degrees C/min in the Kenney extender and in the lactose-EDTA extender. These rates are predicted assuming no intracellular ice formation occurs and that the approximately 5% of initial osmotically active water volume trapped inside the cells at -30 degrees C will form innocuous ice on further cooling. Numerical simulations also showed that in the lactose-EDTA extender, equine sperm trap approximately 3.4% and approximately 7.1% of the intracellular water when cooled at 20 degrees C/min and 100 degrees C/min, respectively. As an independent test of this prediction, the percentage of viable equine sperm was obtained after freezing at 6 different cooling rates (2 degrees C/min, 20 degrees C/min, 50 degrees C/min, 70 degrees C/min, 130 degrees C/min, and 200 degrees C/min) to -80 degrees C in the CPA medium. Sperm viability was essentially constant between 20 degrees C/min and 130 degrees C/min.

Algorithms↗