Five distinctly different types of naphthyl acetate esterase in rat liver were examined for study of liver enzymes during hepatocarcinogenesis. Three types of esterase in normal adult liver were separated by column chromatography. Main esterase in adult hepatocytes, which was demonstrated near the origin in cellulose acetate electrophoresis, was very sensitive to diisopropyl phosphorofluoridate (DFP). The other two esterases showed different electrophoretic mobility, while their K_m values did not differ and both were considerably resistant to DFP.
An anodic minor component in normal adult liver, which had a characteristic esterase pattern of infant liver, increased in the liver of rats fed 3'-methyl-4- (dimethylamino) azobenzene. This esterase was obtained by electrophoresis on Cellogel block. It was partially inhibited by DFP and p-chloromcrcuribcnzoate, activated by cysteine, and showed a different K_m value from the above esterases.
Another minor component situated at the most cathodic side, which had characteristic esterase patterns of fetal liver and hepatoma, was very sensitive to DFP and eserine, and showed a characteristic of nonspecific cholinesterase as proved by staining.

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Subcutaneous injections of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) at the dose of 50mg/kg body weight for 10 days showed depressed production of hemolysin against sheep red blood cells (SRBC) in Wistar rats. On the other hand, oral administration at the dose of approximately 35mg/kg body weight for 30 weeks scarcely suppressed antibody production to heterologous RBC and cellmediated immune response to Walker-256 carcinosarcoma in Wistar rats during the experimental period of 55 weeks. The daily administration by way of oral route proved to be efficient for the induction of stomach cancer. The difference in immunosuppressive effect of MNNG by these two routes will be discussed in relation to the susceptibility of in vivo degradation of the carcinogen.

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Hyperferritinemia in various diseases, mainly hematological, was confirmed by immunological methods. For ferritin detection, anti-human placental ferritin antiserum, anti-human hepatic ferritin antiserum, and anti-human leukemia cell ferritin antiserum were used and the result was compared with each other. Leukemia, malignant lymphoma, multiple myeloma, and aplastic anemia are hematological diseases which showed a positive reaction in this test, among which leukemia showed the highest positivity. Cases of hepatic diseases and non-hematological malignant neoplasms also showed a positive reaction. The positivity was quite low and almost negligible in other diseases and healthy individuals. Anti-human placental ferritin antiserum seemed to be suitable for cancer diagnosis and, antihuman hepatic ferritin antiserum for hepatic diseases.
The result of analysis of purified human hepatic and placental ferritins highly suggested the presence of immunological heterogeneities between them. Also, a possibility was pointed out that one of the components of the so-called leukemiaspecific antigens might sometimes be the isoferritin of leukemia cells.

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Divided doses of 6, 000 or 8, 000 rad of X-ray were given to the gastric region of ICR/JCL female mice with immune atrophic gastritis produced by the injection with allogenic stomach antigen. The carcinogenic effect of X-rays for inducing gastric carcinoma was significantly increased by this method.
Two points can be presented as its reason. First, the pyloric gland mucosa regenerating from injuries by immunization was exposed to the divided doses of X-rays. Second, the marked requirement of gastrin secretion attributable to severe injuries of parietal cell mass by immunization and local X-irradiation acted as a promoting factor on the induction of gastric carcinoma by X-ray for a long time through the trophic effects on the pyloric gland.

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Seven of 35 mate Wistar rats developed well-differentiated adenocarcinoma of the glandular stomach on combined treatment with N-methyl-N'-nitro-N-nitro-soguanidine and 4-nitroquinoline 1-oxide. One of the tumors was successfully transplanted into newborn Wistar rats by subcutaneous inoculation. The latent period after inoculation was less than one month and the growth of the transplanted tumor was slow throughout 10 transplant generations. The tumor appeared nodular or cystic in subcutaneous tissues of rats and often caused ulceration of the skin. The histology of transplanted tumors was very similar to that of the primary tumor, Metastasis to both lungs was observed in one rat of the first transplant generation.

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The level of carcinoembryonic antigen (CEA) in the plasma was measured in 258 patients, consisting of 198 patients with various cancers and 60 with various non-malignant diseases. As the normal control, the plasma CEA level was examined in 330 apparently healthy individuals and the value was 3.1±1.1ng/ml on the average. If the level higher than 4.2ng/ml could be assumed to be above the normal, 109 out of 198 (55%) patients with malignant diseases were considered to show abnormally elevated CEA values. Based on the above criterion, the CEA titer was abnormally elevated only in 11 out of 60 cases (18%) without cancers. Among cancerous patients, the ones with carcinomas of the digestive tract and the lung exhibited a positive titer of CEA higher than 10.1ng/ml.
When the relationship between the plasma CEA level and histological findings in patients with lung cancer was examined, cases with the adenocarcinoma had more elevated titers than those with any other types of lung cancer. It was also found, by the serial estimation of plasma CEA, that the titer dropped after a successful therapy but elevated again with the recurrence of cancer. Repeated estimation of CEA is thought to be valuable as are indicator for clinical phases of cancer patients.

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Protein-bound fucose content in sera from normal persons and patients with various malignant and non-malignant diseases was measured and statistically analyzed. Normal serum gave a mean value of 6.84±0.13mg/100ml, and rarely exceeded 9mg/100ml. Although no significant difference was found between sexes, there was a tendency of fucose content to decrease in older persons. It was noted that more than 90% of cancer-bearing patients have significantly higher level than critical value (9mg/100ml), while only 8.7% of patients with benign tumor showed positive result. These results were not limited to special organs but in common to all cases studied. The elevation of serum fucose content in malignant tumor was well correlated with its stages of progression, though the levels were less significant in early and in rather locally restricted breast and thyroid cancer.
Serial postoperative follow-up study showed that the levels in serum fucose content was a useful parameter for judging the effectiveness of therapy and the prognosis of the patient. The fucose content in malignant tumor tissue and metastasized lymph node appeared to be significantly elevated than that in normal tissue.
The practical usage and limitation of the fucose value in various diseases, together with a possible source of serum fucose were discussed.

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Correlation between infectivity of type-C RNA virus (murine leukemia virus, MLV) and development of leukemia was tested in female ICR/JCL mice treated with either 1-ethyl-1-nitrosourea (ENU) or 1-butyl-1-nitrosourea (BNU). Continuous administration of either chemicals resulted in the occurrence of thymic lymphoma in every mouse with a short latent period. The time of appearance and distribution pattern of MLV infectivity in various tissues were examined by the XC plaque assay technique at fixed intervals during the leukemogenic treatment. In ENU- or BNU-treated mice, only a few samples of the thymus showed MLV infectivity with rather low titers during incubation period and the presence of MLV was not consistent even in leukemic cases though the thymus was almost invariably the target of leukemogenesis. On the other hand, many samples of the uterus, spleen, and mesenteric node from non-leukemic and leukemic mice harbored a good quantity of MLV. In tissues such as the liver, kidney, bone marrow, and muscle, positive cases occurred only sporadically. Observations on the MLV infectivity in untreated controls were almost comparable with those in leukemogen-treated mice. These results indicate that the infectivity of MLV, detected by the XC plaque assay technique, is not necessarily related to the induction of leukemia in mice by exogenous agents.

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Dependence of the survival curves of Burkitt lymphoma cells, which were featured by their small n or D_q values, on linear energy transfer (LET) obtained for different quality of radiation was revealed markedly in the change of D₀ value, together with a small change in n vlaue. Relative biological effectiveness (RBE) compared with D_q, n, and D₃₇ values of Burkitt lymphoma cells for high LET radiation was smaller than that of other cell lines. This finding supports the hypothesis that in Burkitt lymphoma cells the recovery capacity from sublethal damage (D_q) is so small even after low LET irradiation that LET does not modify the suppression of recovery. Similar survival curves with n value closely equal to 1 were obtained for four different mammalian cell lines (Burkitt lymphoma P3HR-1, human melanoma HMV, HeLa-S3, and L5178Y) after 2MeV neutron irradiation. This fact may suggest that the radiation which has an LET value at which n value of the survival curve is to be 1 will be optimum for therapeutic purpose to the radioresistant tumors.

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An experimental model was described for inducing spontaneous lymph node metastasis, in which tumor cells of the rat ascites hepatoma AH-109A were transplanted into the subcutaneous tissue of the penis, which is rich of lymph plexus. Growth of tumor at the site of transplantation was measured serially and metastasis was recognized by palpation in the inguinal lymph nodes initially, and then in the axillary and lumbar nodes. When animals were sacrificed 12 days after transplantation, these lymph nodes were weighed and high percentage of metastasis was confirmed by histological examination. As an experimental model of lymph node metastasis, the usefulness of this method was discussed.

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The pelvic region of male ICR/JCL mice 5∼7 weeks of age was irradiated with 1, 000 rad of X-ray for a total of 8 exposures to determine whether such irradiation would induce prostatic carcinoma. Prostatic adenocarcinoma was observed in 5 of 135 animals which survived more than 12 weeks after the first X-iriaradtion. Because spontaneous development of prostatic adenocarcinoma has not been reported in mice, development of this carcinoma in these animals can be considered to be attributable to X-irradiation.

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The distribution of haptoglobin (Hp) phenotypes in patients with different types of cancer was compared with those in the normal population, with the aid of vertical disc polyacrylamide gel electrophoresis. The Hp¹ gene frequency (0.0647) of the normal population exhibited only a slight difference from that of the cancer patients, as against previous records. The only appreciable difference was in the range of mobility of the Hp² bands from the origin in individuals with Hp 2-1 and 2-2 phenotypes.

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The presence of cell-free Ehrlich ascites tumor fluid in an appropriate concentration was shown to permit a proliferative response, strictly dependent on the presence of Thy-l-positive lymphocytes, to proceed when introduced on the initiation of mixed lymphocyte-tumor reaction of C57BL/6 lymphocytes and Mitomycin-C-treated C3H/He myeloma cells, while it clearly inhibited the development of cytotoxic killer T lymphocytes toward the priming allogeneic tumor cells. The fluid had no effect, however, when added to normally primed spleen cells at the onset of cytotoxicity test.
Further investigation of the mechanism in vitro by which ascitic tumor fluid selectively suppresses the generation of killer T lymphocyte activity to allogeneic target cells may lead to a better understanding of the suppressed T-cell responses observed in Ehrlich tumor-bearing animals, and additionally, may provide an intriguing information about the interactions between the distinct T-cell subsets responsible for proliferative response and generation of killer T lymphocytes.

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A method for the determination of the Bleomycin-inactivating enzyme is described. The amount of conversion of active Bleomycin to inactive Bleomycin is used as a measure for the determination of the Bleomycin-inactivating enzyme activity. The active Bleomycin is determined in a DNA-dependent DNA polymerase assay; in a certain Bleomycin concentration range the resulting reduction of the activity of the DNA-dependent DNA polymerase is correlated linearly when plotted semilogarithmically. By application of this method it has been found that the activity of the Bleomycin-inactivating enzyme is highest in liver and present in lower concentrations in testis, spleen, lung, brain, and skin.

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Cell suspension of a human breast cancer cell line (Hattori line) was injected intraperitoneally into an athymic nude mouse to produce ascites form breast cancer (peritoneal carcinomatosis). Subsequent serial transfers of cancer cells in ascites were also successful in mice. All male and female nude mice injected 1×10⁷ tumor cells died of accumulation of ascites after a latency period averaging 4 weeks, with one exception which died of a wasting disease. Multiple lung metastases were observed in some mice. The tumor cells retained cytological characteristics of the original cell line, and histology of the infiltrating tumor in the peritoneum and omentum was that of poorly differentiated adenocarcinoma. Differentiation not only toward acinar or duct lining cells but also toward myoepithelial cells was observed by histochemistry, immunohistochemistry, and electron microscopy.

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The transplantable argyrophilic gastric carcinoids producing histamine found in Praomys (Mastomys) natalensis contained no significant amount of vitamin B₁₂-binding proteins. It was also demonstrated that the concentration of vitamin B₁₂-binding proteins in glandular stomach of mastomys was much lower than those in the same tissues of the rat or mouse.

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The effect of oil-attached BCG cell-wall skeleton on the induction of pleural fibrosarcomas by 3-methylcholanthrene in mice was examined. The pleural fibrosarcomas were induced by a substernal injection of 3-methylcholanthrene into the thoracic cavity of ddO mice. One week after the injection of 3-methylcholanthrene, 100μg of oil-attached BCG cell-wall skeleton was injected subcutaneously every week for 10 weeks.
In the observation period of 130 days, the incidence of pleural fibrosarcoma was 67% in the control mice and 39% in the mice treated with BCG cell-wall skeleton. The latent period of tumor induction was prolonged in the mice treated with BCG cell-wall skeleton.

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The caffeine potentiation on lethality of L-1210 cells treated with Neocarzinostatin was studied. Colony formation of L-1210 cells treated with Neocarzinostatin was significantly decreased by incubation tofhe cells for 48hr with 0.5mM of caffeine which alone did not affect the growth rate and colony-forming ability of the cells. These results indicate that Neocarzinostatin may induce repairable damage in DNA of L-1210 cells.

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The radiation response of cultured Burkitt lymphoma cell, known as a particular cell line of high radiosensitivity, was studied by the colony formation method. The values of n, D_q, and D₀ derived from the survival curve after a single dose X-irradiation resulted in small values as 1.1, 10rad, and 125rad. The maximum recovery of about 5% was observed 3hr after the irradiation by a split-dose experiment. In the survival curve derived from a split-dose irradiation, n and D_q increased while D₀ remained unchanged. The reason for these increases in n and D_q may be attributed to the nonhomogeneous or mixed population response.

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The antitumor effect of reserve polysaccharide, paramylon, from Euglena gracilis on the transplantable sarcoma-180 was examined in mice. This polysaccharide had an effect similar to that of lentinan. Paramylon, in a dose of 1μg/g body weight, injected intraperitoneally 24hr after tumor implantation had an inhibitory effect on the tumor growth, although without causing complete regression of the tumor. Alkaline-treated paramylon had a similar effect but at a smaller concentration than the native one. The inhibitory activity was not lost when the paramylon preparation was treated with pronase, DNase, or RNase. The antitumor effect might be a lymphocyte-mediated process. In tumors that were regressing after treatment, there was extensive outpouring of lymphoid cells with plasma cells and macrophages. A test conducted using paramylon ruled out the possibility of an interferon-mediated inhibitory effect on tumor growth.

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A total dose of 960mg/kg body weight of 1-β-D-arabinofuranosylcytosine (cytosine arabinoside) was given intraperitoneally to rats bearing Yoshida sarcoma, in a single or divided doses. Single-dose therapy gave an increased life span of about 1 day irrespective of cell population size in accord with the concept of constant percentage cell kill. Tumor cell reduction was estimated to be about 70%. Divided-dose therapy, however, brought about increased life span which was reciprocally proportional to the logarithm of population size. Estimated cell reduction was 87% when population size was 10⁸ cells and 99.95% at 10⁴ cells.

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Cultured cells from Morris hepatoma 7316A contained isozymes I and II, but not isozyme III, of branched-chain amino acid transaminase. They also contained tyrosine transaminase. Isozyme II and tyrosine transaminase were induced by addition of cortisol. These findings agree well with in vivo findings. However, prolonged culture of the cells for over 500 days caused deviation of the chromosomal number and activity of both enzymes, and they were no longer affected by cortisol. A tumor formed by back-transplantation of the cells showed the typical isozyme pattern of rapidly growing hepatomas, such as Yoshida ascites hepatomas, i. e., isozymes I and III. These results were discussed in relation to change of gene expression during culture.

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Addition of K₂Cr₂O₇ (0.1∼0.5μg/ml) to hamster embryonic cells for 24hr led to consistent chromosomal aberrations of cells including gaps, breaks, and exchange. The effect of K₂Cr₂O₇ was reduced by the addition of a reducing agent, Na₂SO₃.

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