W. O. Caster

Tissue weights of the rat. I. Normal values determined by dissection and chemical methods.

Summary A combined dissection and chemical approach to the problem of determining tissue weights has been described. It allows the exact determination of total muscle mass and supportive tissue weight in a fraction of the time required by the complete dissection approach. It also provides estimates of the total marrow weight and the fresh weight of the connective tissue, which are difficult to obtain in any other manner.

Tissue weights of the rat. II. Changes following 700 r total body x-irradiation.

Summary The weight changes observed in 15 tissues at 9 different periods following total body irradiation with an LD50 dose (700 r) of x-ray have been described and statistically evaluated. The loss of muscle mass explains the major portion of the body weight loss which is seen in the rat during the first 4-6 days following irradiation. Though the percentage weight loss was greater in spleen, thymus and marrow, these tissues are too small to have an appreciable effect upon total body weight change.

Urinary Excretion of Thiamine as a Characteristic of the Individual.

Summary 1. The thiamine and pyramin excretions by 2 groups of normal young men maintained on 1 and 2 mg of thiamine per day have been determined on 2 different occasions when the same diet was served on 3 successive days. Each of these periods occurred only after the men had been stabilized at their respective intakes. 2. The thiamine excretion on a constant diet shows a 2 to 3 fold variation for the men within each group and an overlapping of the 2 groups. The pyramin excretion is much more constant and shows no tendency for the values of the 2 groups to overlap. 3. The excretion of thiamine is characteristic of the individual as shown by the rank correlations of the excretion values. This was true over the entire 8 months of the dietary regime and was also true when the above thiamine intakes were reversed. There is no such correlation for the pyramin excretions. 4. The explanation of the thiamine excresion as a characteristic of the individual cannot be found in the fecal excretion of thiamine, the physical activity of the subjects, in the B.M.R. nor in their body weights.