Robert Tennant

Effect of Macromolecular Material from Chick Embryos on Growth Rate of Mouse Heart Fibroblast Cultures.

Summary It is shown that a macromolecular fraction isolated from chick embryo extracts by differential high-speed centrifugation essentially according to Claude, exerts a distinct growth-stimulating effect on cultures of mouse heart fibroblasts. The writers wish to acknowledge the technical assistance of Miss E. Carter and of Mr. H. Nelson in these experiments.

Effect of Golchicine on Human Tumors

The action of colchicine upon division of normal and malignant cells has been studied by several investigators. Dustin 1 described a remarkable increase in the number of mitoses in malignant growths in animals following the injection of colchicine. Ludford 2 found that colchicine applied to cultures of normal and malignant cells of animals brought about an arrest of mitosis for several hours, and that prolonged application destroyed the cells held up in division while the resting cells still survived, and that a single injection in animals produced an arrest of mitosis for several hours. The mitoses were arrested in the metaphase, which Ludford believes is due to the failure of the mitotic spindle to form and function in the normal manner. He also found that the largest accumulation of arrested mitoses occurred in tissue in which cell division is normally of frequent occurrence. This phenomenon has been utilized by others 3 , 4 as an index of the rate of cell growth. It, therefore, seemed that the method might prove of value in studying the growth characteristics of human tumors. The colchicine effect on tumors was studied in a group of 21 patients who received the drug either subcutaneously or intramuscularly. Fifteen of the 21 patients had control biopsies before receiving the colchicine and of this group 11 showed definite arrest of mitosis in the metaphase. A biopsy was performed, when possible, to establish the diagnosis, and to serve as a control. Colchicine was then administered, and in most instances a second biopsy was performed or the entire tumor removed 9 ½ hours later. In certain inaccessible tumors it was impossible to perform a biopsy before the removal of the tumor. However, the colchicine effect could be observed and compared with similar tumors.

Influence of Environmental Change upon Sensitivity of Drosophila Larvae to Ultraviolet Radiation

We have developed in this laboratory a respirometer 1 , 2 , 3 capable of use under any conditions of constant humidity, and a technique of maintenance of drosophila larvae over periods of several days for respiratory studies. The technique and food ordinarily used is described in a report 4 of a study of immediate and subsequent effects of X-ray irradiation upon CO2 respiration of larvae. In studies with ultraviolet light no significant effect upon duration of the prepupal period had been observed such as the extension 5 , 6 , 7 when X-rays were employed; but it seemed worth while to investigate the possibility that similar effects upon respiration might be obtained. Some striking similarities in the action of these two types of radiation were observed, 8 following which we were able to develop a means of affecting the sensitivity of the larvae to ultraviolet radiations. Six random lots∗ of larvae (C1, C2, C3, I1, I2, I3) were maintained simultaneously as in the X-ray experiments mentioned above 4 except additions of glacial acetic acid were made to the regular 25 ml. of food as follows: 0.5 ml. for C1 and I1 1.0 ml. for C2 and I2 and 1.5 ml. for C3 and I3, each. Respiration of CO2 was observed as usual and the lots designated by I were irradiated simultaneously with the radiations from a mercury arc in quartz for 1/2 hour in a stream of air at 26°C. when they had attained a median age of approximately 3.5 days. The results are presented graphically in Fig. 1, where the ordinates of all curves are proportional to CO2 respiratory rate, but in the case of each lot multiplied by a constant in order to superimpose their early portions. However, the ordinate scale approximately represents 10-6 moles per minute. The abscissae represents time in days during the experiment (integral values at midnight), and approximately the median age of the drosophilae.

A Protective Property of Serum in Irradiation of Amylase with Ultraviolet Light

The monomolecular character of the inactivation of pepsin by ultraviolet light has been demonstrated. 1 Recently, similar results 2 have been obtained with amylase, employing a viscosimetric method for estimations of concentration. As in the earlier work, infra-red radiation was absorbed in a filter of 5 mm. of water and it was demonstrated that the interposition of a No. 1 Crookes Glass filter prevented passage of the radiation responsible for the changes otherwise observable. It seemed of interest to ascertain whether or not similar effects could be obtained with amylase in sera. A dilution of about 1 part of dog serum with 4 parts of 0.85% saline (containing 1.56 ± 0.02 units of amylase as estimated viscosimetrically) was irradiated for a period of 3 minutes at 10.0 ± 0.15°C. under conditions such that a simple 0.85% saline solution of pancreatin would have been about half inactivated, according to the findings of the previous work. 2 The estimated amylase concentration after irradiation was 1.52 ± 0.02 units—not significantly different from the previous value (the indicated dispersion measures being the A.D.). In a similar manner solutions containing serum from the same animal mixed in 0.85% saline with pancreatin solution (concentration of amylase, about 10 units) were irradiated with evidence of similar protection in the case of those containing 20% serum even when irradiated under the same conditions for 30 minutes. Finally, such a solution containing but 0.2% serum was about half inactivated in 6 minutes of such irradiation, about half the reaction speed of a similar solution without serum. Other workers have observed protective effects upon enzymes in the irradiation of animals 3 with ultraviolet and other radiation from a mercury are in quartz.