Sequential quantitative analyses were made of pepsinogen 1 (Pg 1) decreased pyloric glands after treating male WKY rats first with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and then with N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) as a second gastric carcinogen or sodium taurocholate (Na-TC) as a gastric promoter. Animals received a single dose of MNNG (160mg/kg body weight) by gastric intubation followed two weeks later by either ENNG in drinking water (100μg/ml) (group 1), basal diet containing 0.25% Na-TC (group 2), or basal diet and tap water (group 3), from weeks 3 to 24. Animals were sacrificed at weeks 8, 12, 16, 20 and 24. Sections of the pyloric mucosa were investigated for Pg 1 immunostaining. In comparison with group 3, induction of Pg 1 decreased pyloric glands was significantly enhanced by ENNG from week 8 and by Na-TC from week 16. The former exerted a significantly stronger effect at each time point. The results suggest that Pg 1 decreased pyloric glands represent a good marker for early detection of gastric carcinogens and promoters in in vivo test systems.

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The effects of naturally occurring antioxidants on rat forestomach epithelium were compared with those of synthetic antioxidants, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), of which the former is a known forestomach carcinogen. Groups of five F344 male rats were given diet containing BHA, BHT, gallic acid, syringic acid, sesamol, caffeic acid, chlorogenic acid, ferulic acid, eugenol or esculin for 4 weeks at a level of 0.7% for BHT or 2% for other compounds. Histological examination of the forestomach showed that BHA induced hyperplasia mainly in the prefundic region near the esophageal orifice, caffeic acid induced pronounced hyperplasia throughout the forestomach epithelium, and sesamol induced large ulcers and hyperplasia in the central region. Thus, these naturally occurring antioxidants showed different toxicities and abilities to induce hyperplasia in the rat forestomach.

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HTLV-I is commonly believed to be transmitted from HTLV-I seropositive mothers to infants via breast milk. In 11 of 24 breast-fed infants born to HTLV-I seropositive mothers, HTLV-I antigen-positive cells were detected in peripheral blood samples obtained 12 months after birth. In sharp contrast, they were detected in only one of 11 bottle-fed infants of HTLV-I seropositive mothers. Thus bottle-feeding appears to be an effective method to avoid HTLV-I transmission from HTLV-I seropositive mothers to infants.

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DNA samples from 5 out of 15 stomach cancers and from 5 out of 15 colon cancers showed transforming activity in NIH 3T3 cells upon transfection. A transforming gene from an NIH 3T3 transformant induced by transfection of DNA from a stomach cancer was cloned, and showed transforming activity amounting to 120 focus-forming units/μg. The transforming gene was identified as hst. The hst gene was also responsible for acquisition of the transforming activity in DNA samples from 2 other stomach cancers and one colon cancer.

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A tyrosine protein kinase inhibitor, erbstatin, showed no antineoplastic effect on L-1210 mouse leukemia when it was injected alone. Erbstatin was found to be inactivated by incubation in serum, but not in dialyzed serum. It was also inactivated in reconstituted serum containing dialyzed serum components and ferric or ferrous ion. Because erbstatin was considered to be inactivated by the ferric or ferrous ion in serum, foroxymithine, which is a potent chelator for the ferric ion, was given to the mice together with erbstatin. Administration of both erbstatin and foroxymithine showed antineoplastic activity against L-1210 leukemia.

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The time course of the change of cellular ATP level was studied in L5178Y cells exposed continuously to various temperatures and compared with that of cell death determined by means of a dye-exclusion test. The ATP level first increased at all temperatures tested and then decreased at temperatures higher than 42°. The onset of this decrease always preceded the beginning of cell death. The results support the idea that the cellular lethality of heat treatment is well correlated with cellular ATP content in L5178Y cells.

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To study the long-term prognosis after gastrectomy, a total of 6, 662 gastrectomized patients who had been operated on for benign gastroduodenal diseases between 1965 and 1980 were followed up from September 1, 1984 to May 30, 1986. The final vital status for the observed period could not be confirmed in 493 patients (7.4%), giving a follow-up rate of 92.6%. The average observation period was 13.1 years. The mortality from total deaths was almost identical to that of the general population adjusted for sex, age, and time trends of mortality, except for lower mortality among males in the first five years after operation. The risk of cancer mortality at all sites was lower than that of the general population, mainly due to the lower mortality from stomach cancer. This trend was not affected either by the type of gastroduodenal disease or by the method of operation. However, lung cancer mortality among males was significantly higher and one of the reasons for that could be excess smoking by males.

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To clarify the relationship between the westernization of dietary habits and the changes of mortality from breast and ovarian cancers in Japan, correlation analyses were performed using data from the Vital Statistics and National Nutritional Survey Reports. With increasing population size of the areas, the age-adjusted death rates (AADRs) for both types of cancer increased together with the per capita intakes of fat, animal protein and western-style foods such as butter & margarine, cheese, ham & sausage and dairy products. The association of the AADRs with the population size was strong after the age group of 45-54 years in breast cancer, and became stronger as the age increased in ovarian cancer. The association of the AADRs with western-style foods was also observed in the correlation analyses among the 12 geographical districts in Japan. From chronological correlation analyses, the correlation coefficients for some nutrients and foods in breast cancer were highest when the “time-lag” between the foods/nutrients intake and the cancer mortality was assumed to be around 10 years. The results of the present study suggest that an increase of western-style fat-rich foods such as butter & margarine, cheese, bread and ham & sausage among Japanese might be associated with the recent increase of AADRs for breast cancer and ovarian cancers in Japan.

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In order to ascertain the minimum induction time, minimum treatment period and total dose required for development of renal cell tumors, KBrO₃ at a concentration of 500ppm was administered in the drinking water to a total of 232 male F344 rats divided into 14 experimental groups and the development of tumors was examined by two different approaches. In a continuedtreatment study, administration of KBrO₃ was stopped at week 13, 26, 39, 52 or 104 and rats were immediately sacrificed for comparison with controls given distilled water (DW) alone. Renal cell adenomas were found as early as after 26 weeks of treatment with KBrO₃. The yields of dysplastic foci, adenomas and adenocarcinomas of the kidney, follicular cell tumors of the thyroid and mesotheliomas of the peritoneum increased with treatment, the final incidences all being statistically significant after administration of KBrO₃ for 104 weeks. To examine the effect of discontinued treatment, on the other hand, the rats were given KBrO₃ for the first 13, 26, 39 or 52 weeks and were subsequently maintained on DW alone until sacrifice at week 104. The incidences of tumors in these groups were compared with that of a group continuously administered KBrO₃ for 104 weeks. The yields of renal dysplastic foci, adenomas and adenocarcinomas in all discontinued-treatment groups were approximately equal to or even higher than those in the group given KBrO₃ continuously for 104 weeks. It is concluded that, under the conditions of this study: (1) the minimum induction time for the development of renal adenomas was 26 weeks and (2) the minimum treatment period and total dose for the induction of renal adenomas and adenocarcinomas were 13 weeks and 4g/kg, respectively, when the rats were maintained thereafter on DW for 2 years.

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Human immunodeficiency virus (HIV), the etiologic agent of acquired immunodeficiency syndrome (AIDS), was rapidly cytopathic to SKT-1B, a cell line established from a patient with adult T cell leukemia, in vitro. This cytopathic effect was preceded by the expression of HIV antigen, defined with a monoclonal antibody (mAb) specific for the core protein (p24) of HIV. SKT-1B is highly susceptible to HIV as compared with MT-2 and H9 cells. HIV is known to be transmitted via blood products, and thus we examined whether or not currently used procedures for manufacturing blood products are safe by using SKT-1B. Lyophilized HIV was heated at 65° for time periods in the range of 10min to 48hr, and the infectivity was examined. The results showed that heating at 65° for less than 2hr was not sufficient to inactivate HIV, but the virus heated for 48hr had no effect on SKT-1B. In addition, HIV completely lost its infectivity on sulfonation, which is commonly used to avoid anaphylactic shock on intravenous infusion of human immunoglobulins. These findings indicate that blood products manufactured by currently used procedures are probably safe with respect to HIV infection.

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The transformation of an immortalized but nonmalignant near-diploid mouse cell line (m5S) by X-ray irradiation was studied, and the chromosome constitutions of the morphologically transformed foci were analyzed. The frequency of transformation increased in a dose-dependent manner. Chromosome analysis revealed that 17 out of 24 transformants showed a common chromosome change, being characterized by a diminution of the C2-ter region of chromosome 13 as compared with the chromosome constitution of the parental untransformed cells. In these transformants, the diminution of 13(C2-ter) was critical in forming transformed foci, but was not sufficient to engender anchorage independence and tumorigenicity. The agar clonability and tumorigenicity were associated with the further appearance of an extra chromosomal segment seen as an abnormally banded region, probably consisting of tandem repeats of actively functioning genes. This experimental system thus revealed the progressive multistep nature of neoplastic transformation initiated by a loss of suppressive function.

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N-Acetyl-S-butyl-L-cysteine, N-acetyl-S-3-oxobutyl-L-cysteine and N-acetyl-S-3-hydroxybutyl-L-cysteine have been isolated and identified (as their methyl esters) from the urine of rats given N-nitrosodibutylamine (NDBA), N-nitrodibutylamine (NO₂DBA) and their 1-acetoxy derivatives. Greater amounts of these N-acetyl-S-alkyl-L-cysteines were detected in the urine after administration of NDBA than of NO₂DBA, and greater urinary excretion of the three N-acetyl-S-alkyl-L-cysteines was observed with 1-acetoxy NDBA than with 1-acetoxy NO₂DBA. This suggests that the markedly different biological activities of NDBA and NO₂DBA might be due, in part, to a difference in their alkylating abilities in vivo.

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A comprehensive mapping of epitopes on the carcinoembryonic antigen (CEA) molecule has been achieved by analyses of the specificities of 146 monoclonal antibodies (MAbs) from more than 300 hybridomas established recently. The reactivities of MAbs were analyzed by radioimmunoassays (RIA) with highly purified preparations of CEA and related antigens including normal fecal antigen-1 (NFA-1), NFA-2 in normal adult feces, nonspecific cross-reacting antigen (NCA) in lung and NCA-2 in meconium. The MAbs could be divided into five groups: group I, 23 clones directed to the NCA-common part of the CEA molecule; group II, 31 clones directed to the normal fecal cross-reacting antigen (NFCA)-common part; group III, 46 clones directed to the NFA-1-common part; group IV, 33 clones reactive with the heterogeneous carbohydrate part; and group V, 13 clones directed to the CEA-distinctive part which seemed to be highly specific for CEA. Mutual inhibitions of CEA binding between MAbs of the individual groups revealed that at least 25 different subgroups can be defined i.e., 4, 7, 8, 4, and 2 subgroups in groups I to V, respectively. The epitopes recognized by the group IV MAbs were found to be sensitive to oxidation with periodate, while the epitopes defined by MAbs of the other groups were resistant to this treatment. A solid-phase sandwich-type RIA system for CEA was established by using 2 MAbs from groups II and III as the CEA catcher and an MAb of group V as the tracer. This assay was shown to exhibit improved cancer-specificity and accuracy in the estimation of serum CEA levels.

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Kinetic analysis of vincristine transport in parental and multidrug-resistant P388 leukemia cells was attempted by indirect assessment of its efflux. Practically, the initial velocity and steady-state level of vincristine uptake by ATP-depleted cells, and its steady-state level in untreated cells, were measured. As a result, a saturable process of not only influx but also efflux of vincristine was observed for the first time with both cell lines, suggesting the existence of a carrier-mediated system for influx and efflux. With increasing extracellular drug concentrations, the contribution of the mediated transport to the total flux was decreased and that of the unsaturable process, that is, simple diffusion, was increased. It should be particularly noted that the K_m and V_max values of efflux in the resistant cells were significantly less and greater, respectively, than those of the sensitive cells, providing a biochemical basis for enhanced efflux as a mechanism of multidrug-resistance. No significant difference in kinetic parameters of vincristine influx and intracellular binding contributing to resistance was found between the two cell lines.

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A new dosage form of mitomycin C (MMC-CH) was tested for toxicity and therapeutic efficacy against intraperitoneally inoculated cancer cells in mice. MMC-CH is a suspension comprising 7.16mg/ml of activated carbon particles, 1mg/ml of mitomycin C (MMC) and 20mg/ml of polyvinylpyrrolidone in saline. The LD₅₀ value determined by means of the Litchfield-Wilcoxon method after intraperitoneal administration was 2.29 times higher for MMC-CH than for MMC aqueous solution. Mice were inoculated intraperitoneally with 2×10⁵ P388 leukemia cells and given an intraperitoneal injection of 10 to 1.25mg/kg of MMC in the form of MMC-CH or MMC aqueous solution 24hr after the inoculation. The median survival time was prolonged to 270.5%, 223.0% or 168.3% by MMC-CH at the dose equivalent to 10, 5 or 2.5mg/kg of MMC, respectively, while it was prolonged to 182.7%, 139.6% or 155.4% by MMC aqueous solution at the dose of 5, 2.5 or 1.25mg/kg of MMC, respectively, as compared with the median survival time in the non-treated group. MMC-CH prolonged the survival time to more than 120% as compared with the same dose of MMC given as MMC aqueous solution, and was less toxic.

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A significant inhibition of the growth of adenocarcinoma 755 tumors in BDF₁ mice was effected by oral tegafur (FT) in combination with oral (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVdUrd), at doses at which neither drug used alone had antitumor activity. The maximum inhibition of tumor growth (97%) was achieved by using a combination of 50mgFT/kg with 10mgBVdUrd/kg but, even at a dose as low as 1mgBVdUrd/kg, the antitumor potency of FT was enhanced. The effect which BVdUrd has on the antitumor potency of FT is apparently due to inhibitory action by bromovinyluracil, the phosphorolytic product of BVdUrd, on the degradation of 5-fluorouracil, the oxidative product of FT, by dihydrothymine dehydrogenase.

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