Anaerobic survey was made on the specimen obtained from the bone marrow and peripheral venous blood of patients with cancer of various origins and of benign diseases. Anaerobic Corynebacterium was isolated from the sternal bone marrow and surgically resected rib, but never from the iliac bone marrow or peripheral venous blood. Most of these anaerobic Corynebacteria were identified as C. liquefaciens. The positive incidence of anaerobic Corynebacterium in the bone marrow was 79.8% in normal young adults, 57.1% in non-cancerous patients, and 31.1% in cancerous patients. As for gastric cancer, the incidence was 45.4% in stage I, 25.0% in stage II, 37.9% in stage III, and 22.0% in stage IV, suggesting the close relation of disappearance of anaerobic Corynebacterium from the sternal bone marrow to the progress of cancer.

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As an accelerator of the antitumor action of Mitomycin-C or allogeneic bone marrow transplantation, anaerobic Corynebacterium has been noted in the course of controlled clinical trial on gastric cancer. Experiments showed the effective inhibitory activity of both living and heat-killed anaerobic Corynebacterium when administered 4 or 7 days before the inoculation of Ehrlich ascites tumor cells, especially by the route of intraperitoneal injection, suggesting the host-mediated action. After sonication of bacterial suspension, the effectiveness was found in the fraction of cell wall and other appendices. Combined use of anti-lymphocyte serum did not depress the antitumor activity of anaerobic Corynebacterium. A direct cytocidal activity on Ehrlich cells was also indicated by mixed culture in vitro.

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Subcutaneous injection of urethan[carbonyl-¹⁴C], 0.2μCi (0.568μg)/g body weight, resulted in the immediate appearance of labeled urethan approximately in equal concentration in all the organs, tissues, and body fluid of both pregnant mice and their fetuses, and labeled urethan was catabolized rapidly within 6hr. When labeled urethan was injected to pregnant mice on day 11, 13, 15, 17, or 19 of gestation in order to compare placental permeability of urethan on various days of gestation, it penetrated the placental barrier completely, and placental permeability of urethan had no relation to the stage of pregnancy. When 1.0mg/g body weight of unlabeled urethan was injected to pregnant mice on day 15 or 19 of gestation, the distribution of urethan was the same as when small amounts were given. However, decrease in urethan levels was much slower, and it took 24hr to decrease to approximately 1% in all the organs. In the offspring of the day 19 urethan-treated group, delivered naturally or by the Caesarian operation, the transplacentally transferred urethan was retained for a very long time. When the injection-parturition interval was shorter, urethan remained longer and in higher concentration in all the organs of newborns than in a longer interval.
These results suggest that the high incidence of pulmonary tumors among the offspring of pregnant mice treated with urethan late in term might be due to the long retention of urethan transferred into newborns through the placenta.

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Localization of group-specific antigens (gs antigens) for avian leucosis-sarcoma virus complexes was studied in mouse ascites sarcoma cells (SR-C3H/He cells) induced by Schmidt-Ruppin strain of Rous sarcoma virus (SR-RSV) and in the virions of SR-RSV, using the indirect method of peroxidase-labeled antibody technique for electron microscopy. Labeled antibody used was highly specific due to purification with immunoadsorbent prepared from the corresponding antigen. The conjugates of the antibody with peroxidase was further purified by ammonium sulfate precipitation and column chromatography.
In SR-C3H/He cells, the specific reaction deposit was observed randomly throughout the cytoplasm, but not in the nucleus or plasma membrane. In SR-RSV, the deposit was found just inside the outer membrane, presumably in the zonal area between the outer and inner membranes of the virion, whereas the nucleoid and its immediate vicinity showed no reaction product. The gs antigens are thought to be localized in those areas having the specific deposit, because no specific reaction product was observed in control experiments.

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A continuous oral administration of N-nitrosobutylurea (NBU) dissolved in drinking water resulted in a high incidence of thymic lymphomas in mice as reported previously.
Cell-free supernatants prepared from the blood and thymic tumor of leukemic C57BL mice were inoculated into newborn syngeneic mice or of W/Fu rats. In C57BL mice, leukemias developed in 3 of 8 mice with a mean latent period of 409 days. In W/Fu rats, 6 of 7 inoculated rats developed either thymic lymphomas or reticulum cell neoplasms with a mean latent period of 238 days. The cell-free supernatant from one of thymic lymphomas was highly active in inducing thymic lymphomas in 100% of recipient W/Fu rats with a mean latent period of 157 days. The latent period shortened with 100% leukemia incidence in the serial animal passage.
The cytotoxic effect of anti-Gross lymphoma serum, directed to the Gross tumorspecific cell-surface antigen, was tested on the cell-free transmitted thymic lymphomas in W/Fu rats and the serum showed a very high cytotoxic effect in all the tested cases. This result strongly suggests that, in mice, the latent leukemogenic virus, especially Gross virus, plays an important rôle in the induction of these lymphomas.
In rats, in contrast to the findings in mice, no positive evidence to support the causative implication of a virus was observed in the NBU-induced leukemias in W/Fu and ACI strains of rats.

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The in vitro effect of OK-432 (NSC-B116209), the lyophilized preparation of penicillin-treated cell suspension of a low virulent strain, Su, of Streptococcus haemolyticus, on the metabolism of rat Yoshida sarcoma, ascites hepatoma AH-130, and mouse Ehrlich carcinoma cells was investigated.
It was confirmed that living cells of Su strain released RNA from the tumor cells by contact in vitro, but OK-432 did not exert such an action at all. However, OK-432 was found to inhibit RNA synthesis and also DNA synthesis to a lesser extent in tumor cells in vitro in proportion to the dose of OK-432 applied.
The effect of OK-432 on the RNA synthesis was compared using human malignant cells, HeLa, and nasopharyngeal carcinoma (NPC-204) cells, and phytohemagglutinin-stimulated normal human lymphocytes in culture. Among them, nasopharyngeal carcinoma cells were the most susceptible to the inhibition by OK-432. Protein synthesis of the carcinoma cells was also found to be highly sensitive to OK-432.
These data seem to indicate that the extent of inhibition of RNA synthesis by OK-432 varies according to the cells tested and is roughly correlated to the susceptibility of tumor cells in vivo.

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By using time-lapse cinemicrography, generation time and mode of death in synchronously growing mouse L cells were analyzed after a pulse-treatment with Bleomycin at the G₁-S transition phase. Approximately 90% and slightly more than 50% of the cells were able to pass through the first cycle after the treatment with 20 and 100μg/ml, respectively. At either concentration, fraction of the cells killed at the first cycle was low although it depended slightly on the concentration of the antibiotic, whereas a large fraction of the cells showed death of their offsprings in the second cycle. This fact indicates that Bleomycin gives the cells a lethal damage most of which becomes apparent only after mitosis.
On the basis of a cumulative frequency distribution of the cell division, two types of damage were considered to be responsible for the prolongation of the first cycle. Greater prolongation was found especially when the cells were killed after mitosis.
Morphological change in the cells observed during the prolonged first cycle was the increase of cross-sectional area and the remarkable granule formation around the nucleus.

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Electron microscopic investigation on the five intrahepatic bile duct carcinoma lines and one anaplastic hepatoma line, which were induced in hamsters by the administration of cycasin and established as transplantable tumor lines, proved the presence of virus-like particles in three intrahepatic bile duct carcinoma lines and one anaplastic hepatoma line. Virus-like particles were distinguished by the presence of characteristic electron-dense radial structures which appeared to emanate from the nudeoid, and were characteristically associated with the rough-surfaced endoplasmic reticulum. They could be interpreted as being identical with the latent virus observed in normal BHK-21 clone 3 cells by Bernhard and Tournier, subsequently in several clones of BHK-21 cells, bovine kidney cell culture, and cells derived from spontaneous or induced hamster tumors by several workers.
Frequency of appearance of these virus-like particles varied with tumor lines. In anaplastic hepatoma line, such particles were first detected in small numbers in the 9th transfer generation, but they were not detected before the 8th transfer generation.

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Cell-free fluid of Ehrlich carcinoma ascites was proved to suppress the immune response in healthy mice when intraperitoneally injected in a dose of 1ml. For the test of the immune response, Jerne's hemolytic plaque count method was used with a slight modification. The cell-free ascites fluid was fractionated by Diaflo ultrafiltration to give 5 fractions, out of which three showed immunosuppressive activity. A fraction named UM-2R (molecular weight 10, 000-1, 000) exhibited the activity most efficiently when administered by an intraperitoneal route and 1 or 2 days before immunization with sheep red blood cells. Even in a small dose of 0.5μg, equivalent to 0.001ml of the ascites, UM-2R inhibited plaque-forming cells in the spleen.

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Methylazoxymethanol acetate was infused only into the distal half of the large intestine of the rat through the anal orifice. Multiple adenocarcinomas were diffusely produced in the entire large intestine with high incidence. In other organs, nephroblastomas and hepatocellular adenomas were found.

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Radioactivity incorporated into liver RNA of mouse was analyzed after continuous administration of ³H-labeled dimethylnitrosoamine solution in drinking water. Labeling of RNA leveled off after the first 2 or 3 days. The amount of 7-methylguanine formed showed its maximum value in this period and then decreased.

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This paper describes histological studies on the effect of 1-naphthyl isothiocyanate and 3-methylcholanthrene on hepatocarcinogenesis in rats treated with diethylnitrosoamine. The results showed that neither 1-naphthyl isothiocyanate nor 3-methylcholanthrene inhibited the hepatocarcinogenic effect of diethylnitrosoamine in rats.

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Neoplastic changes (multiple benign adenomatous nodules) were induced in the liver of all the female rats which had ingested over 1, 200mg of polychlorinated biphenyls (PCB) during over 400 days. In contrast, no such neoplastic changes were observed in the comparable male rat group.

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A single subcutaneous injection of cycasin was given to newborn and suckling mice. The incidence of tumors was much higher in newborns and sucklings of 2, 4, and 7 days old, compared with a group of 14-day-old mice.

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