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Biomedical subjects

M Kitajima

Publications and source records attributed to M Kitajima.

At least 361 records · Page 20Linked to original sources
PubMed1992

Increased drug resistance of cultured human cancer cell lines in three-dimensional cellular growth assay using collagen gel matrix.

We have conducted a three-dimensional cellular growth assay using collagen gel matrix with an endpoint of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H tetrazolium bromide (MTT) assay, on four human gastric and colonic cancer cell lines. Three-dimensionally growing cells in collagen gel matrix were 2- to 180-fold more resistant to mitomycin C, doxorubicin, 5-fluorouracil, and cisplatin than those in monolayer culture, and these resistances were increased further when the cells increased their three-dimensionality. Furthermore, the influence of fibroblasts in the collagen gel matrix on the chemosensitivity of cancer cells was less than that in monolayer culture. Since this new assay using collagen gel matrix with an endpoint of the MTT assay was able to detect the increase of drug resistance of human cancer cell lines by three-dimensional cellular growth using a simple and convenient procedure, it was considered to be more useful than conventional monolayer cultures for evaluating the chemosensitivity of cancer cells.

Adenocarcinoma↗
PubMed1992

Targeting cancer chemotherapy using a monoclonal antibody (NCC-LU-243) conjugated with mitomycin C.

Two kinds of immunoconjugate (T-3M and T-11M) of murine monoclonal antibody with mitomycin C (MMC) were developed using spacers containing a disulfide (T-3M) or thiocarbamate (T-11M) bond. A murine monoclonal antibody (NCC-LU-243) raised against a human small cell lung carcinoma cell line, Lu-24, in nude mice, is an IgG2a monoclonal antibody that recognizes a 145-kDa protein on the cell surface membrane. T-3M and T-11M showed affinity for the LU-243 antigen-positive H-69 cell line but not for the antigen-negative Lu-65 cell line in vitro. In the in vitro MTT assay, the order of efficacy of these compounds was T-11M > T-3M > MMC against antigen positive H-69 and T-11M = MMC > T-3M against antigen-negative K562. When antigen-positive H-69 was transplanted into nude mice for in vivo assay, the maximum tolerated dose of T-3M was twice as high than that of the parent compound MMC. Furthermore, T-3M showed higher antitumor activity against antigen-positive H-69 than MMC conjugated with a non-specific rabbit IgG in vivo. When the maximum tolerated doses of T-3M and MMC were administered to H-69-bearing nude mice, the effect of T-3M was superior to that of MMC, whereas no differences were observed between the antitumor activity of T-3M and MMC against antigen- negative MX-1, a human breast carcinoma. These two immunoconjugates of monoclonal antibody with mitomycin C are thought to be useful for targeting cancer chemotherapy against human small cell lung carcinomas.

Animals↗
PubMed1992

Histopathological development of gastric tumors induced by N-methyl-N'-nitro-N-nitrosoguanidine in rats.

The development of carcinoma was examined in male Wistar rats (n = 120) exposed to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in the drinking water (83 micrograms/ml) for 16 weeks. After MNNG administration, rats were investigated by endoscopic observation, visualization of microvascular structure, and estimation of lectin binding sites. Changes of bile reflux to the stomach was observed endoscopically at 24 weeks as well as the development of gastric mucosal erosions. Protruding and expansive ulcerating carcinomas developed at 36 weeks and had a microvascular pattern similar to that of human adenocarcinoma. Estimation of lectin binding site and pattern was useful to evaluate the malignant potential of cell proliferation. We postulate that endoscopic observation is valuable in investigating the development of gastric carcinoma, and microvascular structure and lectin binding pattern may be useful to demonstrate the mechanism of growth of gastric carcinoma.

Animals↗
PubMed1992

Demonstration of bicarbonate secretion in rat duodenal brush border membrane vesicles.

This study was designed to characterize the mechanisms available for bicarbonate transport across the apical membrane using rat duodenal brush border membrane vesicles (BBMVs), including the morphological findings. BBMVs were purified using a double Mg2+ precipitation technique. Electron microscopy of the final pellet showed only membrane material without contaminating organelles of cytoskeletal aggregates. BBMVs were enriched 15.1 +/- 3.2-fold in A-lp and 12.5 +/- 2.4-fold in LAP. The time course of 36Cl uptake into BBMVs demonstrated a good response curve and equilibrated to the intravesicular space over 120 min. In this present study, these BBMVs were purified and showed a stabilized structure. Therefore, these results suggest that this model was useful for studying HCO3- secretion and ulcer etiology.

Animals↗
PubMed1992

Production of human immunoglobulin G reactive against human cancer in tumor-bearing mice with severe combined immunodeficiency reconstituted with human splenic tissues.

Splenic tissues derived from patients with gastric cancer were implanted into mice with severe combined immunodeficiency (SCID) and then the mice were challenged with COLO-205, a human colon cancer cell line. Production of human immunoglobulin G (IgG) reactive against the COLO-205 cells was detected by enzyme-linked immunosorbent assay in sera from the reconstituted and tumor-bearing SCID mice. The titers of the reactive IgG relative to total IgG in the sera of SCID mice began to increase from one week after implantation of the tumor cells, and became 10- to 100-fold higher than that in the donor's serum by 3-4 weeks. This model using implantation of human cancer cells in SCID mice reconstituted with human splenic tissues would facilitate further studies of human cancer immunology.

Animals↗
PubMed1992

Recombinant human interferon-alpha 2a increases hormone receptor level of a human breast carcinoma xenograft in nude mice and enhances the anti-proliferative activity of tamoxifen.

The effect of recombinant human interferon-alpha 2a (rhIFN-alpha 2a) on the hormone receptor level and antitumor activity of tamoxifen (TAM) was investigated in nude mice using ZR-75-1, an estrogen receptor (ER)-positive, and progesterone receptor (PgR)-negative human breast carcinoma xenograft. ER levels (maximum binding sites) of tumors treated with rhIFN-alpha 2a at a dose of 6 x 10(5) U/mouse/day for 1 or 3 wk were not significantly different from the control, whereas those with rhIFN-alpha 2a at a dose of 6 x 10(4) U/mouse/day for 1 or 3 wk were higher than the control (3.9- to 4.4-fold) with a significant difference at P < 0.01. The increase of ER by rhIFN-alpha 2a was investigated using a sucrose density gradient method. The peak was only seen at 8S in both rhIFN-alpha 2a-treated tumor and control ER, and the sedimentation patterns were almost the same, suggesting that both ERs were essentially equivalent. On the other hand, PgR of all the treated groups could be detected, while that of the control group was undetectable. The antitumor effect of the combination treatment of rhIFN-alpha 2a and TAM was compared with those of single treatments. While rhIFN-alpha 2a at a dose of 6 x 10(5) U/mouse/day and TAM did not show a combination effect, rhIFN-alpha 2a at a dose of 6 x 10(4) U/mouse/day and TAM showed a synergistic combination effect, and ER was decreased to the threshold of detection by the combination treatment. These findings indicated that a low dose of rhIFN-alpha 2a increased the ER levels of ER-positive human breast cancer in vivo as well as in vitro and enhanced the anti-proliferative effect of TAM, and the newly synthesized ER was essentially the same as the original ER.

Animals↗
PubMed1992

[Problems in multidisciplinary treatment from the standpoint of clinical characteristics in human cancers].

We investigated the amplification and expression of oncogenes in human gastric and breast cancers. The biological malignancy of the cases with oncogene amplification/expression was higher than that of the cases without amplification/expression. Moreover, the case with amplification/expression of oncogene was found to be highly correlated with distant organ metastasis. In strongly suggests the necessity of postoperative adjuvant therapy. In addition, these data will have to be taken into consideration as deciding on the way of operation and therapy.

Breast Neoplasms↗
PubMed1992

[Rapid detection of mecA gene by nested PCR for diagnosis of methicillin resistance in Staphylococcus aureus].

In recent years, the most common causative organism of hospital infections has been methicillin resistant Staphylococcus aureus (MRSA). The major mechanism of beta-lactam resistance in MRSA is attributed to the production of a specific penicillin binding protein (PBP2'), which is a product of mecA gene, with extremely low binding affinities to beta-lactams. In the present study, we have established a rapid identification method of MRSA by sensitive detection of mecA gene using nested PCR. Nested PCR method amplifying the target DNA in two steps enhanced the efficiency of the second round amplification. By means of this method, mecA gene was successfully detected in clinical samples, such as blood, pus, sputum and feces within 3-4 hrs. Rapid diagnosis of MRSA-bacteremia is particularly important for prevention of sever systemic infection. There are some strains of S. aureus which possess mecA gene in spite of low minimal inhibitory concentration of DMPPC. In these strains expression of mecA gene is induced by contact of beta-lactams and they obtain methicillin resistance. Using nested PCR method, these latent MRSA are rapidly and certainly detectable. This method should be useful for early and effective detection of MRSA hospital infections.

Cross Infection↗
PubMed1992

[Study of DDS to the lymph node-metastases of the gastric cancer by the endoscopic injection of Lip-ADM].

We studied the drug delivery and anti-tumor effect of the endoscopic injection of liposomal adriamycin (Lip-ADM) in the submucosa of stomach by rabbit model. Concerning the drug delivery to regional lymphnode, the lymphnode ADM concentration of Lip-ADM injection group was higher than that of free ADM group (p less than 0.05). We also studied the lymphnodes pathohistologically. The lymphnodes of the rabbits injected with Lip-ADM indicated massive necrosis, whereas those of the rabbits injected with free ADM indicated residual tumor. Among clinical cases, patients injected Lip-ADM had paraaortic lymphnodes in which the adriamycin remained 10 days. The endoscopic injection of Lip-ADM into the submucosa of the stomach appeared to be an effective drug delivery system.

Animals↗
PubMed1992

[Targeting cancer chemotherapy using temperature-sensitive liposomes containing adriamycin conjugated with monoclonal antibodies].

Liposomes have a specific liquid-crystalline phase transition temperature (Tc), at which they release an entrapped drug. Temperature-sensitive liposomes containing adriamycin (TS-Lip-ADM) were made of dipalmitoylphosphatidylcholine (DPPC, Tc: 41 degrees C), distearoylphosphatidylcholine (DSPC, Tc: 54 degrees C), cholesterol and adriamycin. Monoclonal antibodies against human alpha-fetoprotein (AFP) were conjugated to TS-Lip-ADM. When liposomal suspension was immersed in a bath, the release rate of ADM from TS-Lip-ADM = Ab increased, as the temperature increased from 34 degrees C to 42 degrees C. ADM release was dependent on the temperature.

Antibodies, Monoclonal↗
PubMed1991

Clinical usefulness of chemosensitivity testing using the MTT assay.

The results of in vitro chemosensitivity testing using the MTT assay of tumor cells from 140 patients were analyzed with reference to the clinical antitumor effects of the chemotherapy. One hundred and twenty-four (88.6%) of 140 specimens were successfully tested by the method of Mosmann (J Immunol Methods 65:55-63, 1983) with some modifications. When the results of the assay were compared with the clinical effects of chemotherapy in 22 patients with remaining measurable tumor lesions, the overall prediction rate was 86.4% (19/22). Among 31 patients with stage III-V gastric and colorectal carcinomas without remaining measurable tumor lesions, the survival rate of nine patients treated with drugs shown to be effective in the assay was significantly (P less than 0.05) better than that of 22 patients treated with drugs shown to be ineffective.

Adult↗
PubMed1991

Gastric microcirculation and its regulating factors in stress.

Gastric mucosal blood flow and its regulating factors were studied in normal and stressed rats. In addition, vascular regulating factors and the role of CoQ10 anion radical and SOD (superoxide dismutase) level in gastric mucosa were also investigated as well as the influence of 5-HT (5-hydroxytryptamine) on gastric mucosal blood flow. Gastric mucosal blood flow was measured by the hydrogen gas clearance method. The vascular pattern of the stomach was investigated by the infusion method with two-colored silicon rubber. CoQ10 anion radical and SOD levels in gastric tissue were assayed by electron spin resonance (ESR) and radioimmunoassay. The gastric mucosal blood flow decreased significantly early after the induction of stress. Impairment of gastric mucosal blood flow was highly correlated with 5-HT and CoQ10 anion radical and SOD levels. Reduction in gastric mucosal blood flow was consequently due to opening of arteriovenular shunt and hyperpermeability of true capillaries influenced by 5-HT. These results demonstrate that ischemia and reperfusion after reduction of the gastric mucosal blood flow resulted in the sequence of events that led to formation of acute gastric mucosal lesions.

Animals↗
PubMed1990

Does glucagon improve the viability of ischemic intestine?

The effects of glucagon, heparin, urokinase, thromboxane synthetase inhibitor (OKY-046), and the free radical scavengers, superoxide dismutase and catalase (SOD + CAT), on the viability of ischemic intestine were evaluated based on various parameters measured. The mucosal blood flow, the fluorescence pattern, and the histopathological findings in a rabbit model with 3.5 hr total vascular occlusion of a short small intestine indicated that glucagon improved the ischemic intestine. Glucagon increased, tremendously, the mucosal blood flow by 112% in the ischemic intestine compared with that of 25% in the nonischemic intestine. This indicated that vascular spasm, not reperfusion injury or thrombosis, played the initial role in the progression of transmural bowel necrosis. In addition, the outcome in the viability of the ischemic intestine was not detected by the fluorescence technique but was able to be detected through the mitochondrial morphology under the electron microscope.

Animals↗