The in vivo techniques for studying human body composition have built up an important field and are continuing to be developed. This review provides an overview of the present status of this field and describes the in vivo techniques used in mearsuring human body composition such as anthropometry, metabolites method, densitometry, dilution method, total body potassium, neutron activation analysis, bioelectrical impedance analysis, dual energy X ray absorptiometry and imaging method. The review also introduces the principle, method and value of these techniques.
Anthropometry ; methods ; Body Composition ; Densitometry ; methods ; Humans ; Magnetic Resonance Spectroscopy ; methods ; Plethysmography, Impedance ; methods ; Whole Body Imaging ; methods

When using pressure-type plethysmography to test lung function of rodents, calculation of lung volume is always based on Boyle's law. The precondition of Boyle's law is that perfect air is static. However, air in the chamber is flowing continuously when a rodent breathes inside the chamber. Therefore, Boyle's law, a principle of air statics, may not be appropriate for measuring pressure changes of flowing air. In this study, we deduced equations for pressure changes inside pressure-type plethysmograph and then designed three experiments to testify the theoretic deduction. The results of theoretic deduction indicated that increased pressure was generated from two sources: one was based on Boyle's law, and the other was based on the law of conservation of momentum. In the first experiment, after injecting 0.1 mL, 0.2 mL, 0.4 mL of air into the plethysmograph, the pressure inside the chamber increased sharply to a peak value, then promptly decreased to horizontal pressure. Peak values were significantly higher than the horizontal values (P<0.001). This observation revealed that flowing air made an extra effect on air pressure in the plethysmograph. In the second experiment, the same volume of air was injected into the plethysmograph at different frequencies (0, 0.5, 1, 2, 3 Hz) and pressure changes inside were measured. The results showed that, with increasing frequencies, the pressure changes in the chamber became significantly higher (P<0.001). In the third experiment, small animal ventilator and pipette were used to make two types of airflow with different functions of time. The pressure changes produced by the ventilator were significantly greater than those produced by the pipette (P<0.001). Based on the data obtained, we draw the conclusion that, the flow of air plays a role in pressure changes inside the plethysmograph, and the faster the airflow is, the higher the pressure changes reach. Furthermore, the type of airflow also influences the pressure changes.
Air Movements ; Animals ; Models, Theoretical ; Plethysmography, Whole Body ; instrumentation ; methods ; Pressure ; Rats ; Respiration

BACKGROUND: Airway responsiveness after acute inhalation of ozone is related to the concentration and duration of ozone exposure. Using barometric whole-body plethysmography and increase in enhanced pause (Penh) as an index of airway obstruction, we measured the response of BALB/c mice to acute ozone inhalation to study the time course change of pulmonary function after ozone exposure. METHODS: Penh was measured before and after exposure to filtered air or 0.12, 0.5, 1, or 2 ppm ozone for 3 hr (n=6/group). In addition, Penh was measured 24, 48 and 72 hr after ozone exposure. Bronchoalveolar lavage (BAL) and histopathologic examinations were performed. RESULTS: The increase in Penh after ozone exposure was significantly higher in the 0.12, 0.5, 1 and 2 ppm groups compared with the control group (all p< 0.01). Increases in Penh 24 hr after ozone exposure were significantly lower than those immediately after acute ozone exposure; however, increases in Penh 72 hr after ozone exposure were significantly higher than those in the control group (each p< 0.01). The proportion of neutrophils in BAL fluid was significantly higher in the group exposed to 2 ppm ozone than in the groups exposed to filtered air or 0.12 ppm ozone (both p< 0.01). CONCLUSION: These results indicate that airway obstruction is induced following ozone exposure in a concentration-dependent manner and persists for at least 72 hr.
Airway Obstruction/*etiology/*pathology ; Animals ; Animals, Newborn ; Bronchoalveolar Lavage Fluid/cytology ; Disease Models, Animal ; Female ; Mice ; Mice, Inbred BALB C ; Plethysmography, Whole Body/*methods ; Probability ; Reference Values ; Respiratory Function Tests ; Risk Assessment ; Sensitivity and Specificity ; Statistics, Nonparametric ; Sulfuric Acids/*adverse effects