A technique was devised for obtaining marrow-free trabecular bone so that the trabecular and cortical bone composition of dog, steer, monkey and man could be studied. Vertebral body was cut in the frontal plane into slices 2 m m thick with an electric band saw, The cortical bone encircling each slice was trimmed off with a cleaver, leaving intact a lacy slice of trabecular bone. The marrow substance was washed away by fine and powerful jets of tap water obtained from a n adjustable nozzle. Marrow washing was discontinued when no trace of red color was visible on holding the slice in front of a strong light source.The quantities of water, volatile inorganic, organic and ash fractions in cortical bone was alike for all species. Likewise, the trabecular bone fractions of each was quantitatively similar. In general, density and amount of ash in cortical bone was higher than that in trabecular bone. The water and ash:organic ratio were higher in trabecular than in cortical bones.Ratios of trabecular to cortical ash for the bones in an entire dog skeleton were also determined. Based on this, volume or mass of the various bone fraction may be estimated when the weight of the ash for any particular bone is known.
Steer.1. Cortical bone.
The techniques of prompt gamma neutron-activation analysis for the measurement of total-body nitrogen and whole-body counting for the measurement of total-body potassium were used to determine the mass of muscle and nonmuscle lean tissue and their protein content in 135 normal male and female subjects, 20-80 yr of age. Age-related changes in the size of the muscle and nonmuscle compartments and their protein content provide basic data for the investigation of protein metabolism in aging subjects and in individuals with various metabolic disorders, particularly wasting diseases such as cancer. Significant age-related changes in the size of various body compartments were noted. The loss of muscle mass and its protein content contrasts with the relative constancy of the nonmuscle lean tissue and suggests that skeletal muscle is particularly vulnerable to the aging process.
Cross-sectional and longitudinal changes in body composition with age were examined in white women to determine the relationship of body cell mass to menopause and of body fat to bone mass. There was statistical evidence for a curvilinear component to loss of total body potassium with negligible rates of loss before menopause. Longitudinal measurements also indicated a relationship between the proximity to menopause and the rate of loss of potassium. Total body potassium was significantly related to total body calcium and bone density of the spine, radius, and femoral neck. Total body fat was not related to any of these measurements. We found no evidence that adiposity plays a major role in protecting against bone loss.
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