Austin M. Brues

Biological Studies with Arsenic76 II. Excretion and Tissue Localization

Summary 1. Arsenic excretion was studied in man, rats, and rabbits. Less than 10% of the excreted arsenic is found in feces in any of these species; rats have by far the slowest rate of excretion. 2. Data are given for arsenic distribution in various organs in man, the rat, the rabbit, and 2 strains of mouse. 3. The degree of individual variation within each species was very great; in contrast to man and to other animals studied, the rat retains most of the injected dose in the blood for a considerable length of time. 4. The ratio of arsenic concentration in kidney, liver, and spleen of healthy inbred mice was found to be fairly constant for a given time after administration, and this ratio is suggested as a criterion for effects of various types of treatment. 5. Using this ratio as criterion, it was found that arsenic distribution is altered by the presence of transplanted tumors. 6. Factors changing arsenic distribution are discussed in relation to effects on levels of sulfhydryl-containing substances.

Effect of testosterone propionate upon thyroid and parathyroid glands of intact immature female rat.

Conclusion Testosterone propionate is capable of stimulating the thyroid and parathyroid glands of the intact immature female rat. This stimulation is manifested by increased mitotic activity and by histological evidence of functional activity.

Growth Inhibitor in Liver Tissue

Liver has been known for a long time to contain substances which inhibit growth and migration of cells from explants. Walton 1 observed that extracts of liver had an inhibiting effect on tissue cultures, in contrast to all other tissue extracts tried. Lynch 2 and Lewis 3 noticed that no cells migrate from cultures of chick embryo liver after the sixteenth day, and it has been suggested that the inhibitor in liver may be responsible for this effect. Despite the great amount of work that has been done on extracts and substances which increase growth of tissues in vitro or make possible their prolonged cultivation, relatively little attention has been paid to inhibitors. The following is a report of investigations made in this laboratory on the inhibiting power of liver extract. We have used, in general, first explants of embryonic and sarcomatous tissues, grown by the usual coverslip or Carrel flask techniques in solid plasma media. In order to get a quantitative measure of inhibition, we have compared the average radial growth in a test solution at a given time with that in a control medium consisting of plasma and Tyrodes solution, using tissues explanted at the same time from the same embryonic organ. Of course, Parker 4 has shown that the growth rates of fibroblasts from different parts of the same organ may vary; we have found, however, that by using series of 5 or more explants a growth index can be obtained which does not vary more than 10 or 15% from series to series, or from day to day in the same series.