title: Photon activation analysis as a new technique for body composition studies.
abstract: A study was undertaken to demonstrate the usefulness of the recently developed photon activation analysis (PAA) technique for in vivo body composition studies. PAA can be used for direct measurement of total-body oxygen, nitrogen, and carbon. Sequential measurements were made on rats fed diets of 0%, 4.2%, or 20% protein for 6 1/2 wk, and significant changes in body composition were noted. In addition, rats of different ages, strains, nutritional states, and degrees of obesity were included in a comparison of PAA results in vivo with results from chemical analysis after sacrifice of the animals. High positive correlations were found between PAA measurements of carbon and chemical analysis measurements of fat and between PAA measurements of oxygen and chemical analysis measurements of total-body water. A low positive correlation was found between PAA measurements of nitrogen and chemical analysis measurements of protein.
mesh_terms: D000201:Activation Analysis / Q000379:methods*; D000818:Animals; D001823:Body Composition; D001835:Body Weight; D002244:Carbon / Q000032:analysis; D004032:Diet; D008297:Male; D009584:Nitrogen / Q000032:analysis; D009765:Obesity / Q000378:metabolism; D010100:Oxygen / Q000032:analysis; D011506:Proteins / Q000032:analysis; D011827:Radiation; D051381:Rats; D011919:Rats, Inbred Strains; D011924:Rats, Zucker
chemical_list: D011506:Proteins; D002244:Carbon; D009584:Nitrogen; D010100:Oxygen