Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CALORIMETRY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,189 records · Page 66Linked to original sources
PubMedDate not supplied

Day-to-day variance in measurement of resting metabolic rate using ventilated-hood and mouthpiece & nose-clip indirect calorimetry systems.

BACKGROUND: To know if the magnitude of change in resting metabolic rate (RMR) observed during an intervention is meaningful, it is imperative to first identify the variability that occurs within individuals from day to day under normal conditions. The 2 most common systems used to measure RMR involve a ventilated hood or a mouthpiece & nose clip to collect expired gases. The variation in measurement using these 2 approaches has not been systematically compared. METHODS: RMR was measured in 10 healthy adults during 5 separate testing sessions within a 2-week period where usual diet and physical activity were maintained. Each testing session consisted of one measurement of RMR using a ventilated hood system, followed by another using a mouthpiece & nose-clip system. RESULTS: No significant difference in RMR was evident between measurement sessions using either indirect calorimeter. Oxygen consumption and RMR were significantly higher using the mouthpiece & nose-clip system. Average within-individual coefficient of variation for RMR was significantly lower for the ventilated-hood system. RMR measures were consistently lower using the ventilated-hood system by an average of 94.5 +/- 63.3 kcal. Day-to-day variance was between 2% and 4% for both systems. CONCLUSIONS: The use of either system is appropriate for assessing RMR in clinical and research settings, but alternating between systems should be undertaken with caution. A change in RMR must be greater than approximately 6% (96 kcal/d; 1.2 kcal/kg/d) or approximately 8% (135 kcal/d; 1.7 kcal/kg/d) when using a ventilated-hood system or a mouthpiece & nose-clip system, respectively, to observe any meaningful intervention-related differences within individuals.

Analysis of Variance↗
PubMed2000

Determination of hydration kinetics of sulfaguanidine anhydrate in aqueous solution by calorimetry.

A heat conduction microcalorimeter was used to evaluate the isothermal transition in water from anhydrate to monohydrate at 298 K. Sulfaguanidine (SGN) anhydrate was used as a model compound for the measurement of hydration kinetics in water. It is the well-known that SGN is very slightly soluble in water and capable of existing as the anhydrate or monohydrate form in the solid state. The transition rates of SGN anhydrate to monohydrate in tablets and granules were investigated. The hydration kinetics of tablets with controlled surface areas, obtained by coating the side with paraffin in aqueous solution, followed an apparent zero-order mechanism. On the other hand, the transition mechanism of the granules involved a phase boundary-controlled contracting interface reaction.

Calorimetry↗
PubMed1997

Indirect calorimetry, body composition and small bowel function in asymptomatic HIV-seropositive women.

Extrapolation of data from energy balance studies in HIV-seropositive men to HIV-seropositive women may be inaccurate due to gender differences in body composition, hormones and metabolism. If women have a different metabolic response to the human immunodeficiency virus (HIV), nutritional advice may differ from HIV-seropositive men. Ten asymptomatic HIV-seropositive women were matched with 10 heterosexual female controls from low-risk groups. Subjects and controls had assessment of energy and protein intake, resting energy expenditure (REE) and substrate oxidation, small bowel absorption and permeability and body composition. There were no significant differences in REE, substrate oxidation and body composition. Energy and protein intake and small bowel permeability were increased and sugar absorption decreased in HIV-seropositive women (all P < 0.05). Unlike asymptomatic HIV-seropositive men, asymptomatic HIV-seropositive women do not have significant alterations in metabolism or body composition. Therefore, nutritional advice may need to vary according to the gender of the asymptomatic HIV-seropositive subject.

Adult↗
PubMed2003

Differential scanning calorimetry of the effects of Ca2+ on the thermal unfolding of Pseudomonas cepacia lipase.

Thermal unfolding of P. cepacia lipase was observed by adiabatic differential scanning microcalorimetry in the absence and presence of calcium ions at pH 8, and thermodynamic parameters of unfolding were evaluated to analyze the unfolding mechanism of the enzyme. The temperature of unfolding was higher at higher concentrations of Ca2+. From the Ca2+ concentration-dependence of the unfolding temperature, the number of calcium ions that dissociated from the enzyme molecule upon unfolding was estimated to be one. These results confirmed the validity of the unfolding mechanism proposed previously: NCa2+ < = => D + Ca2+, where N and D represent the native and denatured states, respectively, of the enzyme.

Burkholderia cepacia↗
PubMed2005

Determination of the polymorphic forms of bicifadine hydrochloride by differential scanning calorimetry-thermogravimetric analysis, X-ray powder diffraction, attenuated total reflectance-infrared spectroscopy, and attenuated total reflectance-near-infrared spectroscopy.

The pharmaceutical compound bicifadine hydrochloride, which has been found to crystallize in two polymorphic forms, has been characterized by thermal analysis, X-ray powder diffraction (XRPD), infrared (IR) spectroscopy, and near-infrared (NIR) spectroscopy. A series of 22 sample mixtures of polymorph 1 and polymorph 2 were prepared and calibration models for the quantitation of these binary mixtures have been developed for each of the XRPD, attenuated total reflectance (ATR)-IR, and ATR-NIR analytical techniques. The quantitative results were obtained using a partial least squares (PLS) algorithm, which predicted the concentration of polymorph 1 from the XRPD spectra with a root mean standard error of prediction (RMSEP) of 4.4%, from the IR spectra with a RMSEP of 3.8%, and from the NIR spectra with a RMSEP of 1.4%. The studies indicate that when analyses are carried out on equivalent sets of spectra, NIR spectroscopy offers significant advantages in quantitative accuracy as a tool for the determination of polymorphs in the solid state and is also more convenient to use than both the ATR-IR and XRPD methods. Density functional theory (DFT) B3LYP calculations and IR spectral simulation have been used to determine the nature of the vibrational modes that are the most sensitive in the analysis.

Bridged Bicyclo Compounds, Heterocyclic↗