ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
Traditional methods of measuring total body water and fat content of animals that require sacrificing specimens are generally unacceptable when endangered species, or large animal sizes, or humans are involved. These methods are also unsuitable for following changes of fat and water content in individuals. An alternative method, based on the nonresonant absorption of a rf electromagnetic field has been used for constructing a new body composition analyzer. As the electrical conductivity of lipids is approximately 20 times lower than that of lean tissues, the rf power absorbed by the animal provides information which enables one to calculate the lean body mass and total body water. The new instrument measures rf power absorbed by an animal by measuring the quality factor (Q) of the resonant circuit with an animal placed inside the coil. Numerical calculations of the rf power absorbed by a cylindrical object containing 0.9% NaCl aqueous solution have also been performed. Experimental values confirmed the calculated dependence of the absorbed power on the cylinder radius. The device built has been calibrated on 9 males and 11 females of laboratory mice. The amount of lipids was then measured by ether extraction. The relation between instrument reading, which is proportional to the power absorption, and lean body mass (LBM) or water mass (WM) was linear and highly significant: the simple regression coefficients of determination were 0.983 for LBM, and 0.990 for WM (p〈0.001). It has been found that for an individual animal with a body mass ranging from 15.9 to 40.7 g, the accuracy of measurement was ±1.6 g for LBM and ±1 g for WM. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1145525
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