Biomedical subjects

T Shibata

Publications and source records attributed to T Shibata.

1,251 records · Page 70Linked to original sources

PubMedDate not supplied

Modulation of the rat tumor-associated shedding antigen (CE7) and augmentation of immunogenicity by irradiation.

We have previously reported that rat fibrosarcoma KMT-17 cells and their in vitro counterparts, cloned A3 cells, shed a tumor-associated antigen (TAA), termed CE7, from the cell surface on vesicular membranes, under growth-enhancing conditions. This study shows that irradiation (1 approximately Gy) from a 60Co source, inhibited A3 cell growth dose-dependently and correspondingly increased CE7 expression by A3 cells as determined by anti-CE7 monoclonal antibody using flow cytometry. CE7 expression gradually increased with increasing doses of irradiation and reached a peak level at 30Gy. After 30Gy irradiation, CE7 expressing A3 cells were fixed with 1% paraformaldehyde and were used to intradermally immunize syngenic rats. Immunized rats developed transplantation resistance to the parent KMT-17 cells as compared to rats immunized with unirradiated A3 cells. Rat MHC class 1 antigen expression was slightly decreased by irradiation and therefore, resistance to tumor transplantation appeared to arise solely due to the enhancing effects of irradiation on TAA expression which increases the antigenicity of the tumor cells coverting them to an effective stimulator of antitumor effector cells. This phenomenon may offer a possibility of the resistance to the re-emergence and metastasis of the tumor like a KMT-17 through the induction of antitumor memory cells.

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PubMedDate not supplied

Potential interference by free fatty acids in determination of tricyclazole in brown rice by gas chromatography with flame thermionic detection.

A convenient method is described for the determination of tricyclazole in brown rice, and the interference of free fatty acids with flame thermionic detection (FTD) is reported for the first time. Brown rice is extracted with acetone, the extract is filtered, and the filtrate is evaporated. To the residue is added 10% (w/v) NaCl solution, and the mixture is extracted with ethyl acetate. The extract is charged on a Sep-Pak Plus silica cartridge. Free fatty acids are removed from the rice by washing with diethyl ether, and tricyclazole is eluted with acetone-n-hexane (1 + 1). Tricyclazole is determined on a DB-1 capillary column by gas chromatography with FTD (GC-FTD). Linoleic acid and oleic acid, which have essentially the same retention time as tricyclazole, cannot be detected by FTD. Thus, without the Sep-Pak Plus silica cleanup, the peak height of tricyclazole in the chromatogram decreased, the extent depending on the concentration of linoleic acid. n-Hexane-acetonitrile partitioning was not used for cleanup because it could not remove 50% of the free fatty acids. Recoveries (mean +/- standard deviation, n = 5) of tricyclazole from rice fortified at 2 and 0.1 ppm were 90.5 +/- 9.4% and 81.3 +/- 10.6%, respectively. The limit of quantitation was 0.05 ppm.

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PubMedDate not supplied

Targeted hyperthermia using dextran magnetite complex: a new treatment modality for liver tumors.

BACKGROUND/AIMS: Dextran magnetite complex (DM) is a colloidal suspension of subdomain magnetite particles ('magnetic fluid'). It has been reported that DM generates a great amount of heat in an AC magnetic field. MATERIAL AND METHODS: In this experimental study on Japanese white rabbits, a new treatment modality for liver tumors was examined in which the tumor is selectively heated with an intravascularly administered DM-containing embolic material followed by external application of an AC magnetic field. RESULTS: The heat generation of DM in vitro was found to be more than 3-fold greater than that with magnetite particles of 40-micron diameter. As a DM-containing embolic material, we developed a DM/Lipiodol emulsion. When DM/Lipiodol emulsion was injected into the hepatic arteries of the rabbits following VX2 tumor transplantation into the liver, embolization of the artery and selective heating of the embolized liver were successfully attained following exposure to a 100-kHz AC magnetic field of approximately 15000 A/m. Histological examination of the embolized liver disclosed that DM had accumulated in the hypervascular, viable part of the tumor. CONCLUSION: These results demonstrate the potential feasibility of using a DM-containing embolic material for targeted hyperthermia of liver tumors.

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PubMedDate not supplied

Enhancement of tumor antigen expression and inhibition of pulmonary metastasis of rat fibrosarcoma cells by local radiotherapy.

Pulmonary metastasis formation after local radiotherapy against a rat fibrosarcoma was investigated. KMT-17 fibrosarcoma cells were transplanted into the hind leg in syngeneic WKA rats and two different doses (30Gy, 60Gy) of irradiation from a 60Co source were applied 5 days after transplantation. Pulmonary metastasis was inhibited by 30Gy irradiation rather than 60Gy irradiation, which was enough to almost completely cure the local tumors. This inhibitory effect of 30Gy irradiation was induced by the continued presence of irradiated tumors. As for pulmonary metastasis, the different effects of irradiation doses were not recognized when the tumor was removed surgically 1 day after irradiation, but when it was removed 4 days after 30Gy irradiation significantly inhibited metastasis. Expression of tumor-associated antigen (TAA), termed CE7 antigen, on the cell surface was enhanced effectively and continuously by 30Gy irradiation rather than by 60Gy. With this increase in CE7-expressing cells, the enhancement of anti-tumor immunity of spleen cells was observed in an in vitro 125I-IudR release assay and an in vivo tumor-neutralizing assay (Winn assay). The above results suggest that an appropriate dose of irradiation such as 30Gy, to a local tumor can efficiently enhance the TAA expression and that TAA-expressing cells may stimulate anti-tumor immunity, resulting in inhibition of pulmonary metastasis. This phenomenon may offer the possibility of resistance to micrometastasis through the induction of antitumor effector cells.

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PubMedDate not supplied

Enhancement of tumor associated antigen expression during the regression phase of xenogenized tumor cell growth in vivo.

Rat fibrosarcoma cells infected with Friend leukemia virus (FV-KMT-17) grow for a short time and then regress spontaneously in syngeneic hosts. This regression was caused by immunological mechanisms, because the tumor cells were renogenized. In this study, we have tried to find out whether tumor-associated antigen (TAA) expression in these xenogenized tumor cells can be modulated by xenogenization. FV-KMT-17 cells (1 x 10(7)), which were subcutaneously transplanted into ten rats, spontaneously regressed after temporary growth. All rats which rejected FV-KMT-17 cells showed strong resistance to rechallenge with KMT-17 (1 x 10(6)) cells. To reveal the chronological modulation of TAA and virus-associated antigen (VAA), a single-cell suspension was obtained from the subcutaneous tumors and expression of these antigens was chronologically measured. TAA, termed CE7 antigen, was examined by anti-CE7 monoclonal antibody (MoAb) and VAA was examined by anti-FK1 MoAb which recognizes the FV env gene product (gp 70). Expression of VAA was not modulated through either the progression or the regression phase, but expression of TAA was strongly enhanced in the regression phase. These results show that enhancement of TAA expression occurs during the regression phase of FV-KMT-17 growth in vivo and that TAA-expressing cells may stimulate anti-tumor immunity, resulting in acquisition of resistance against parental KMT-17 cells.

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PubMedDate not supplied

The LEC (Long-Evans Cinnamon) rat as an animal model for bilirubin-induced tooth pigmentation.

The LEC (Long-Evans Cinnamon) rat is well known as a useful animal model for hepatic disease. We noticed the green pigmentation in incisors 2-3 weeks after acute hepatitis accompanied by severe jaundice. This study was undertaken to elucidate the cause of this phenomenon. Half of the pigmented teeth were examined by histopathological analysis and microradiographic analysis. Pigmentation was observed as a green stripe that ran parallel to the incremental line in the dentine. The microradiographic analysis disclosed enhanced permeability of the pigmented area as compared with other areas. The rest of pigmented teeth were dried, powdered and bilirubin was extracted with chloroform /methanol/acetic acid, 30:10:0.5; v/v under sonication. After centrifugation, the supernatant was collected and evaporated. The residue was dissolved in chloroform and its absorption spectrum measured after diazo reaction to reveal the presence of bilirubin. The spectral characteristics indicated the presence of bilirubin in the pigmented teeth. Thus, the LEC rat may be useful animal model for bilirubin-induced tooth pigmentation.

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PubMedDate not supplied

Immunological analysis of enhanced spontaneous metastasis in WKA rats following cryosurgery.

We have previously reported that inhibition of anti-tumor immune responses and enhancement of metastatic tumor growth occurred in rats following cryosurgery of the transplantable 3-methlcholanthrene-induced rat fibrosarcoma KMT-17. In this study, to elucidate the immunological responses in rats following cryosurgery, we examined whether rat serum obtained from rats which underwent cryosurgery (c-serum) might affect the in vivo neutralizing activity of the Winn assay. In this assay, c-serum did not reduce the anti-tumor immunity, though spleen cells obtained from rats undergoing surgical excision indicated strong anti-tumor immunity as compared with cryosurgery. Thus, we examined the anti-tumor responses of spleen cells. Macrophages were obtained from the glass adherent fraction of rat spleen cells following cryosurgery and these macrophages were used for cytostatic activity against KMT-17 cells. Cytostatic activity was not reduced by cryosurgery. The spleen cells obtained from rats receiving cryosurgery were intravenously transferred into other rats that were previously immunized with 80 Gy-irradiated KMT-17 cells, and an alteration of tumor growth modulated by this adoptive cell transfusion was observed. The anti-tumor resistance of rats was diminished by the adoptive transfusion of spleen cells treated with cryosurgery, though this diminution disappeared following anti-T serum and immune complement treatment of spleen cells. These results suggest that immuno-suppression following cryosurgery may be mainly caused by suppressor T cells.

Adoptive Transfer↗

PubMedDate not supplied

Transcatheter arterial chemoembolization through collateral arteries for hepatocellular carcinoma after arterial occlusion.

PURPOSE: The purpose of this study was to evaluate the efficacy of transcatheter arterial chemoembolization (TACE) through collaterals after hepatic artery occlusion or severe stenosis in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: During the past three and one-half years, 19 of 167 patients with HCC showed hepatic artery occlusion or severe stenosis after repeated TACE, and 17 patients underwent TACE through collateral arteries. Types of collaterals, results, and effects of TACE through collaterals were evaluated. RESULTS: Common collaterals were periportal collateral, intrahepatic anastomosis, and right inferior phrenic artery. TACE was successfully carried out through all detected collaterals in 40 of 49 TACE trials (82%). In eight of 49 TACE trials (16%), TACE through collaterals was partially carried out. The cumulative survival rates at the end of the first, second, third, forth and fifth year were 100%, 79%, 79%, 59% and 59%, respectively. CONCLUSION: TACE through collateral arteries was able to be performed in most cases and will be an effective treatment to control HCC.

Aged↗

PubMedDate not supplied

Enhancement of experimental pulmonary metastasis and inhibition of subcutaneously transplanted tumor growth following cryosurgery.

We have previously reported that inhibition of anti-tumor immune responses and a corresponding enhancement of metastatic tumor growth occurred in rats following cryosurgery of 3-methylcholanthrene-induced WKA rat fibrosarcoma (KMT-17). In this study, to evaluate the enhancement of metastasis arising from the inhibition of anti-tumor immune responses following cryosurgery, we examined how cryosurgery affected experimental pulmonary metastasis and the growth of subcutaneously transplanted tumor. To reveal the effect of cryosurgery on pulmonary metastasis, rats received a subcutaneous inoculation of KMT-17 tumor in the right flank (1 x 10(6)) and i.v. injection (1 x 10(5)) on the same day or 4 days later. The right flank tumors were treated with cryosurgery 5 days after subcutaneous transplantation. The pulmonary metastasis of the rats, which were injected i.v. one day before treatment, was enhanced by cryosurgery as compared with surgical excision, though the pulmonary metastasis of rats, which were injected i.v. 5 days before treatment, was un-affected by cryosurgery. These observations suggest that cryosurgery may enhance the pulmonary metastasis in its early steps but has no effects in its later stages. To reveal the effect of cryosurgery on the growth of distant tumors, rats received subcutaneous inoculations of KMT-17 tumor in the right (1 x 10(6)) and left (1 x 10(4) approximately 10(5)) flanks. Tumors in the right flank were treated with cryosurgery 5 days after inoculation and the growth of untreated left flank tumors was observed. In this double grafted tumor system, however, cryosurgery significantly inhibited the growth of the untreated left flank tumors. Spleen cells obtained from rats which had undergone cryosurgery 4 or 10 days previously (cryo-spleen cells) were used for in vivo neutralizing Winn assay. Antitumor activity of cryo-spleen cells was decreased as compared with that of rats after surgical excision in both spleen cells from 4 and 10 days after treatment. These findings suggest that effector cells in the spleen may not participate in subcutaneous tumor regression and that the evaluation of antitumor effect using the double grafted tumor system needs caution.

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