Radioactive alkylated bases, ribose or phosphate, were never found either in acid and alkaline hydrolysates of polyribonucleotides or in alkaline hydrolysates of DNA after incubation with ¹⁴C-dimethylnitrosamine (DMNA) in a microsomal system.
Two radioactive compounds, which were co-chromatographed with methylamine and N-methylhydrazine, respectively, on column, paper, and thin-layer, were always detected. They differed from the compound derived from 7-methylguanosine after the alkali-mediated fission of the imidazole ring in its molecule.
The in vitro system employed well represents the in vivo situation (7-methylguanine which is liberated from DNA after acid hydrolysis); however, it has given results which do not agree with the generally-accepted mechanism of DMNA alkylation at the N-7 position of guanine.

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Relationship between neonatal treatment with estrogen and induction of mammary tumors by 7, 12-dimethybenz [a] anthracene (DMBA) in female rats was examined. Five-day-old female rats received intrahypothalamic implantation of micronellets of 0.4μg of estradiol-paraffin mixture or paraffin vehicle only (sham-operated control), or no operation (intact control). Induction of mammary tumor in these rats was examined after DMBA was given at 45 days of age intragastrically. The rats bearing the micropellets of the estradiol-paraffin mixture in the anterior to middle part of the hypothalamus became persistent vaginal estrus while the rats bearing the same pellets in the middle to posterior part of the hypothalamus showed regular cyclic changes in daily vaginal smears. Compared to the intact or sham-operated controls, mammary tumor appearance was delayed in the rats which received 0.4μg of estradiol intrahypothalamically and became persistent vaginal estrus (10 weeks vs. 15 weeks after DMBA administration, respectively). Since (1) the vagina of the rats with intrahypothalamic micropellets of estradiol-paraffin mixture opened at the same age as the intact or sham-operated controls and (2) the mammary rating of the former rats was the same as the latter, it can be concluded that the hypothalamus of the former rats has been changed by the steroid while the neonatal mammary glands have received little effect. Thus, the delay or suppression of mammary tumorigenesis in DMBA-treated rats by neonatal steroid administration is primarily attributable to the irreversible changes in the hypothalamo-pituitary-gonadal axis.

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In a search for infectious Epstein-Barr virus (EBV)-producer cell sources, 36 EBV genome-carrying lymphoblastoid cell lines originating from various sources in Japan were screened. Three cell lines derived from different sources were found to release infectious EBV into the culture fluid. EBV from these 3 lines possessed leucocyte-transformation activity but did not induce early antigen formation. One of the three lines, NHAd-60, originated from an adenoid tissue; it released a relatively large amount of infectious virus (10² to 10³ of 50% of transforming dose of cord leucocytes). The NHAd-60 virus strain was further characterized. Cellular, virological, and immunological properties were described and discussed, and compared with EBV from known producer cell lines.

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Mouse myeloid leukemia line cells, Ml, could be induced to differentiate in vitro into macrophages and granulocytes with ascitic fluid of animals bearing various tumors. Ml cells could not be induced to differentiate with dimethyl sulfoxide alone.
During the culture of Ml cells, spontaneously appearing cells resistant to factors stimulating differentiation (D-factor) in ascitic fluid were isolated. These resistant cells were more refractile to the toxic action of dimethyl sulfoxide than sensitive cells and grew in culture medium with 1% dimethyl sulfoxide.
Although the resistant cells were not induced to differentiate with dimethyl sulfoxide alone, they were sensitized with the aid of dimethyl sulfoxide to undergo differentiation with the D-factor in ascitic fluid

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Synthetic 5'-amino-5'-deoxythymidine (5'-AdThd), α, β-methylenethymidine diphosphate (α, β-MTDP), and α, β-methylenethymidine triphosphate (α, β-MTTP) were found to inhibit thymidine kinase. Using thymidine kinase extracted from FM 3A/B cells (a strain of mouse mammary gland tumor cells), the K_i values of 5'-AdThd, α, β-MTDP, and α, β-MTTP against thymidine were calculated to be 9.2 × 10^-5M, 2.3 × 10^-5M, and 1.8 × 10^-5M, respectively. At concentrations above their Ki values α, β-MTDP and α, β-MTTP did not inhibit incorporation of labeled thymidine into DNA of cultured cells, whereas 5'-AdThd did. Under the same conditions all three compounds inhibited TMP incorporation. The inhibitions of thymidine and TMP incorporation were specific, since the incorporation of deoxyguanosine was scarcely inhibited by 5'-AdThd. These results suggested that the specific inhibition of thymidine and TMP incorporation was mostly due to reduction in permeability of the cells to these substrates rather than to inhibition of thymidine kinase activity.

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A newly-devised multidisciplinary therapy, combining chemotherapy with surgical thoracotomy, was experimented on blood-borne metastases of syngeneic sarcoma of WKA rat lungs yielding satisfactory results.
The therapy consists of two different but interrelated methods; the preliminary one applied to one-side of the lung and the principal one applied to both lungs. In the former method (Method I), regional hyperthermic chemothorax (37°) combined with temporary occlusion (20∼30min) of the hemipulmonary blood circulation under general hypothermia was applied to one of the two lungs, both bearing blood-borne tumor metastases, and was quite effective on the treated unilateral lung, though not effective on the contralateral lung under systemic administration of carboquone.
In the principal method (Method II) which was applied to a both lungs, occlusion of the blood circulation was not made, so that the regional hyperthermic chemothorax (40°) treatment could be safely performed for 30∼60min under general hypothermia.
When Method II was applied to the bilateral lungs of a rat using carboquone as the anticancer agent, metastases in both lungs were successfully cured at a considerably high rate. There were two rats which survived over 6 months after receiving the therapy despite the fact that all untreated and drug-injection alone control rats died of severe pulmonary metastases within 4 weeks.

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Antitumor activity of 1-(γ-chloropropyl)-2-chloromethylpiperidine hydrobromide (CAP-2) was studied in vivo and in vitro, using various rat ascites hepatoma cell lines. Among eight ascites hepatoma cell lines, AH-13 was extremely sensitive both to in vivo antitumor and to in vitro lethal action of the agent, whereas AH-44 was resistant in both cases. The sensitivity of ascites hepatoma cell lines to CAP-2, nitrogen mustard N-oxide, 4-nitroquinoline 1-oxide, and ultraviolet ray in vitro was widely different but their relative sensitivities were very similar against these agents. For all the agents, AH-13 was inactivated very rapidly and AH-109A moderately, whereas AH-44 was relatively resistant. These results indicate that the sensitivity of the cells to CAP-2 may be closely related to their repair-capability of damaged DNA.
Similar experiments using various DNA repair-deficient mutants of Escherichia coli B strain demonstrated that the repair-deficient mutants were several times more sensitive to CAP-2 than the wild type strain. From these results, it may be concluded that CAP-2 induces DNA lesions repairable by the same repair mechanisms that work on pyrimidine dimers.

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Studies were made on whether N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN), N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT), N-2-fluorenylacetamide (2-FAA), and 3, 3'-dichlorobenzidine (3, 3'-DCB) had synergistic carcinogenic effects; they were administered singly, or two or three together to rats at noncarcinogenic doses and resulting changes in the urinary bladder were examined.
The incidence of focal hyperplasia of the bladder epithelium, a preneoplastic change, was significantly higher in the groups treated with BBN plus FANFT, BBN plus 3, 3'-DCB, BBN plus 2-FAA, and BBN plus 3, 3'-DCB plus 2-FAA than in those treated with BBN, FANFT, 3, 3'-DCB, or 2-FAA alone. It was also higher in the group treated with 2-FAA plus FANFT than in that treated with 2-FAA alone. The incidence of papilloma was significantly higher in the group treated with BBN plus FANFT than in those treated with BBN or FANFT alone and it was higher in the group treated with BBN plus 2-FAA than in those treated with BBN or 2-FAA alone.
The incidence of transitional cell carcinoma was significantly higher in the group treated with BBN plus FANFT than in the group treated with BBN only. Thus synergistic effects on bladder tumorigenesis were observed on administration of BBN with FANFT, 2-FAA, and/or 3, 3'-DCB. The effects of BBN and FANFT were most synergistic.
Liver lesions, such as fatty changes, cystic dilatation of the bile duct, oval cell proliferation, nodular hyperplasia, and cancer developed in rats treated with 2-FAA alone or in combination with BBN or FANFT. These liver changes were rare on treatment with 3, 3'-DCB plus 2-FAA.

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The effects of the sequential administration of 0.01% N-butyl-N-(4-hydroxy-butyl) nitrosamine (BBN), 0.15% N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT), 0.025% N-2-fluorenylacetamide (2-FAA), and 0.3% 3, 3'-dichloro-benzidine (3, 3'-DCB) on urinary bladder carcinogenesis were examined in male Wistar rats. Each chemical was administered for 4 weeks in various combinations. BBN for 4 weeks resulted in no histopathological changes, mild diffuse cell growth, and/or focal hyperplasia after 4, 8, 12, or 16 weeks of observation. No bladder carcinomas were present in rats given only BBN or any one of the other 3 chemicals. Statistically significant incidences of bladder carcinomas occurred with the sequential administration of all 4 chemicals or the first 3 chemicals without 3, 3'-DCB. Bladder cancer was also present in rats administered the sequence of FANFT, 2-FAA, and 3, 3'-DCB. No antagonistic effects between chemicals were observed.

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Early surface changes of the bladder epithelium of male rats, mice, hamsters, and guinea pigs induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) were examined by light microscopy and scanning electron microscopy. The normal bladder epithelium is 2∼4 cells thick in all 4 species. It increased diffusely to 5∼8 cells thick in rats and mice, and to 4∼6 cells thick in hamsters after 4 weeks of treatment with BBN. No increase in thickness was observed in guinea pig bladder epithelium. On treatment with BBN for 8 weeks, focal hyperplasia developed in the bladder epithelium of rats and mice, but not in that of hamsters and guinea pigs. On treatment with BBN for 12 weeks, papillomatous growths were observed in a few rats, focal hyperplasia in mice, diffuse cell growth in hamsters, and no changes in guinea pigs. Scanning electron microscopy showed that the surface of the normal bladder epithelium of each species appeared to be smooth with a net-work of fine ridges on regularly arranged cells which had no microvilli or cilia. On BBN treatment, microvilli were seen on the bladder surface in rats, mice, and hamsters after 4 weeks but not in guinea pigs even after 12 weeks. Cells in areas of focal hyperplasia in rats and mice appeared irregularly arranged and their surface was uneven with numerous microvilli. Of the 4 species, the rat showed the most marked changes, and multiple foci of papillary mucosal projections were already present in rats after 8 weeks of BBN treatment. Thus, the differences in the susceptibility of the urothelium of the bladder in different animal species to BBN were reflected in their fine structure.

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Sporamycin is an antitumor antibiotic isolated from the culture filtrate of Streptosporangium strain No. PO-357. Hydrolysate of the antibiotic showed at least 12 kinds of amino acid, and the molecular weight was calculated approximately as 8, 500∼9, 000. Antitumor activities of Sporamycin were examined on murine tumors according to different schedules of treatment. After nine daily doses of the antibiotic had been given to dd mice bearing Ehrlich ascites carcinoma, significant increase of lifespan was observed at doses of 5.0∼1.3mg/kg. A marked decrease in tumor size of sarcoma-180 transplanted subcutaneously was observed when the mice were treated by daily or single injection of Sporamycin. Against leukemia P-388 and L-1210 inoculated intraperitoneally into CDF₁ mice, the antibiotic increased lifespan of leukemic mice. The antibiotic also inhibited significantly the growth of human tumor cells in vitro.

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Antitumor activity of N-heterocyclic carboxaldehyde thiosemicarbazone derivatives was examined in ascites sarcoma-180 system. Among isoquinoline-1-carboxaldehyde thiosemicarbazone derivatives, the parent compound, IQ-1, was the most active and less toxic. On the other hand, among the pyridine-2-carbox-aldehyde thiosemicarbazone derivatives tested, 5-acetoxymethyl and 5-isonicotinoyl derivatives were active, and their therapeutic indices were 190 and 54, respectively.
In other tumor systems, acetoxymethyl derivative was markedly active against Ehrlich ascites carcinoma, leukemia L-1210, and leukemia C-1498, while moderately effective against Nakahara-Fukuoka sarcoma, but it was not active against adenocarcinoma-755. Isonicotinoyl derivative was markedly active against Ehrlich ascites carcinoma, leukemia L-1210, and leukemia C-1498, while moderately active against adenocarcinoma-755, and slightly active against Nakahara-Fukuoka sarcoma.

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In the medium containing dextran sulfate, 3T6 cells stopped growth at almost monolayer stage and showed decreased saturation density. This action of dextran sulfate is referred to as a growth restriction.
About 70% of untreated 3T6 cells formed piled-up colonies whereas the remaining 30% formed monolayer colonies. Fraction of the latter increased with increasing concentration of dextran sulfate in the medium.
Cell lines sensitive and insensitive to the growth-restricting action of the compound were cloned from colonial culture of the wild type cells. Sensitive cells showed a slightly less saturation density than the wild type cells in the presence of dextran sulfate. Insensitive cells grown in dextran sulfate medium showed almost the same growth rate and saturation density as the untreated wild type cells grown in the absence of the compound.

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Corynebacterium parvum and Corynebacterium liquefaciens were comparatively examined for their antitumor activity against sarcoma-180 in ddY mice. In the case of ascitic form, significant antitumor effect was observed when C. parvum was administered on days -4 and -2 or day -2. As for solid form, maximal effect was obtained when C. parvum was administered on day 0.
On the other hand, C. liquefaciens exhibited maximal antitumor activity against sarcoma-180, both in ascitic and solid forms, when it was administered on days -4 and -2. However, no significant difference in respect to antitumor activity against sarcoma-180 was seen between C. parvum and C. liquefaciens (ascitic form, F¹₁₁₈=0.09, P<0.05; solid form, F¹₅₃=0.03, P<0.05).

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A series of administration of 7, 12-dimethylbenz [a] anthracene given at biweekly intervals by gastric intubation to juvenile male rats of the Sprague-Dawley strain elicited considerable number of mammary carcinomas, leukemias, and ear duct tumors. The evoked leukemia shared two main types; 51.6% of erythroblastic stem cell and 48.4% of myelogenous.

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Mouse myeloid leukemia cells were induced by some corticoid hormones to migrate in agar, phagocytize, and change into forms which were morphologically similar to macrophages and granulocytes. Inducing ability of corticoids was correlated with glucocorticoid activity, not mineralocorticoid activity. Other steroids were ineffective to induce differentiation of myeloid leukemia cells. Glucocorticoid-resistant cells, which could not differentiate even in a high concentrations of dexamethasone, were selected from steroid-sensitive cells by stepwise increase in concentrations of dexamethasone in culture medium.

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Antitumor activity and bone marrow toxicity of a new nitrosourea analog, 1-(β-D-glucopyranosyl)-3-(2-chloroethyl)-3-nitrosourea (GANU), were compared with those of 2-[3-(2-chloroethyl)-3-nitrosoureido]-D-glucopyranose (Chlorozotocin) and 1, 3-bis(2-chloroethyl)-1-nitrosourea (BCNU). GANU was found to be highly active against mouse leukemia L-1210 when administered intraperitoneally or intravenously, being the same degree as Chlorozotocin. Even by oral route, GANU exhibited significant activities, whereas Chlorozotocin failed to show any activities by this route. Studies on the bone marrow toxicity as measured by the depression of white blood cell counts and the marrow cellularity revealed that both GANU and Chlorozotocin were less toxic than BCNU. GANU, however, seemed to be rather more toxic than Chlorozotocin.

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The frequency of persistent nucleoli increased in the Yoshida sarcoma cells treated in vitro with 4-nitroquinoline 1-oxide. Carcinogenic derivatives of 4-nitroquinoline 1-oxide seem to increase the frequencv of persistent nucleoli, compared to noncarcinogenic derivatives.

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Benzo [a] pyrene-3, 6-and 1, 6-semiquinone radicals formed by reduction of the corresponding benzo [a] pyrene-quinones were found to bind covalently with DNA by incubation at 37° for 18hr in aqueous solution of dimethyl sulfoxide. No binding was detected when benzo [a] pyrene-6, 12-semiquinone radical was used. Binding was specifically large for poly (G) when polynucleotides were used.

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Dietary phenobarbital markedly enhanced hepatocarcinogenesis by 3'-methyl-4-(dimethylamino) azobenzene in rats. This effect was reflected in the number and size of resulting carcinomas and ATPase-deficient islands. Sequential study of the islands seemed to suggest that phenobarbital truly increases cancer production rather than merely accelerates cancer appearance from preneoplastic lesions.

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