Acta Medica Okayama 25巻 4号

Newborn mice of C3Hf/Bi (Zb) strain were divided into three groups and injected, intracranially with adenovirus type 12 alone, subcutaneously with 20 mgjkg of N, N'-dimethylnitrosourea following intracranial inoculation of adenovirus type 12, and subcutaneously with 20 mgjkg of N, N'-dimethylnitrosourea alone at 10 days of age, respectively. With adenovirus type 12 alone, intracranial tumors were induced in 12 out of the 25 effective animals. With N, N'-dimethylnitrosourea following adenovirus type 12, intracranial tumors were produced in 19 out of the 21 effective animals and these tumors were virus-induced ones. With N, N'-dimethylnitrosourea alone, no intracranial tumors were induced. In control mice, administered subcutaneously with 20 mgjkg of N, N'.dimethylnitrosourea within 24 hr after birth, necrosis of the external granular cells and hypoplasia of the granular layer of the cerebellum was observed.

As a step in the elucidation of human cancer immunity we studied antitumor activity of lymphoid cells by conducting a series of cultures using the primary culture of cells from spontaneous mammary cancers from C3H and RIll mice mixed with autochthonous lymphoid cells, and obtained the following results. 1) With 24 mammary tumors obtained from 24 mammary cancer. bearing mice, we prepared 22 suspensions containing sufficient numbers of free tumor cells, and attempted primary culture with them. As a result we were able to attain satisfactory primary culture cells in 18 trials. 2) With each group of the 18 primary culture tumor cells we conducted mixed cultures with autochthonous lymphoid cells (mainly spleen cells) in proportion of 1 : 40, for 48 hours, and counted viable tumor cells after the culture. As a result it was found that in 11 trials the lymphoid cells showed antitumor activity. In the remaining 7 groups of lymphoid cells there could be observed no antitumor activity, but some of them showed tendency to slightly accelerate the growth of tumor cells. 3) On looking at the correlation between the antitumor activity of lymphoid cells and the ratio of tumor weight/body weight, it was revealed that the antitumor activity is greatest when the tumor is around 10% the body weight, and as the tumor grows larger, such antitumor activity disappears. From these results, it may be concluded that even in spontaneous mammary cancer of mouse, autochthonous lymphoid cells exhibit anti. tumor activity on indigenous tumor, and this seems to indicate that cell. mediated immunity has been established.

By inoculating E. coli B into the semisynthetic medium we conducted shaking culture, and observed alterations of the total phospholipid contents and the amounts of individual phospholipid components in various stages of growth. The results are briefly summarized as follows. 1. The total phospholipid content has been found to be greater during early culture period, while it decreases as the growth age advances. 2. Phosphatidyl ethanolamine gradually increase as the culture period approaches the stationary phase. 3. Phosphatidic acid and phosphatidyl glycerol decrease precipitously as growth age advances. 4. Cardiolipin shows the maximum content in the middle log phase when the growth rate is most speedy.

Circular DNA isolated from human kidney mitochondria was studied by electron microscopy. I. Mean contour length of monomers of the mitochondrial DNA was 4.96 ± SE 0.28 /μ 2. The complex molecules (oligomers) of mitochondrial DNA were observed in frequency of 6.2 per cent. Among them circular dimers accounted for two per cent of all circular DNA molecules. 3. Circular DNA fibers with an intermediate perimeter between the　monomer and dimer, and with a contour length shorter than 3 μ were occasionally observed. 4. Some discussions were made on the emergence of the circular dimer.

Electron microscopic observation of replicating SV 40 DNA has revealed the existence of two types of RF, e form and (1 form. The frequency of RF at 54 hours after infection was 8.9% for the e form and 4.3% for the (1 form. Morphological evidence exhibits that in (1 form RF the tails are, predominantly, shorter than the viral genome and double length SV-40 genomes are also capable of replication in SV-40 infected VERO cells.

The effect of 6.MPR on the antibody formation of rabbits challenged with bovine serum albumin has been studied in comparison with that of 6.MP. Observation revealed that the antibody formation is profoundly suppressed when the animal is treated with 6.MPR in an appropriate dose and period in relation with the introduction of antigen. Discussion was made of the possibility of 6.MPR as a superior therapeutic agent for autoimmune diseases.

Under in vivo conditions JTC-II cells derived from Ehrlich ascites　tumor are led to destruction by lymph node cells by two processes. The　one is the interaction of lymph node cells of the C57BL (♀) mouse sensitized with Ehrlich ascites tumor cells, and the other is the interaction of　normal C57BL (♀) mouse lymph node cells treated with PHA-M. In　these two reaction systems the following differences have become clear. The regional lymph node cells from the C57BL (♀) mouse sensitized　with Ehrlich ascites tumor cells show a marked inhibitory effect on the　growth oflTC-II cells by 10 days after sensitization.　In the observations under the phase contrast microscope these lymph node cells tend to adhere around the antigenic cells by culture hour 5-6, and by culture hour 24-48 they lead the latter to undergo cytolysis. The normal lymph node cells of C57BL (♀) mouse treated with PHA show anti-growth effect oflTC-II cells. PHA-M used proves to be effective in the concentration of 2% (v/v). Likewise after such normal lymph node cells are previously treated with 2% PHA-M for 12 hours, they also inhibit the growth of lTC-II cells when two cell groups are cultured together. In such intercellular reaction between the two cell groups there is no specificity. By observations under the phase contract microscopy, by culture hour 2-3 the adherence and aggregation of lymph node cells begin to occur, and by 18-24 hours of culture the target cells are led to undergo cytolysis. In this instance, lymph node cells are prone to adhere and aggregate on one side of the target cell.