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M Namba

Publications and source records attributed to M Namba.

At least 145 records · Page 8Linked to original sources
PubMed1995

Transfected mutant p53 gene increases X-ray-induced cell killing and mutation in human fibroblasts immortalized with 4-nitroquinoline 1-oxide but does not induce neoplastic transformation of the cells.

We introduced the mutant p53 gene (codon 273Arg-His) into human fibroblasts (SUSM-I cells) previously immortalized with 4-nitroquinoline I-oxide (4NQO) and obtained 2 clonal cell lines (SUSM-i/p53-1 and SUSM-1/p53-6) expressing the mutant p53. Since the genetic background of SUSM-1/p53 is the same as that of SUSM-1 except for the presence of the mutant p53, we expected to obtain more information on the mechanisms of p53 functions without the influence of other genetic differences by comparing cellular characteristics of both cell lines. SUSM-1/p53 cells became about twice as sensitive to the cytotoxic effects of X-rays as their parent SUSM-1 cells. Mutation frequency was determined by the appearance of hypoxanthine guanine phosphoribosyl transferase deficient (6-thioguanine resistant) cells. As a result, the mutation frequency of SUSM-1/p53 cells was about 5 times that of SUSM-1 cells transfected with or without the vector plasmid alone. Furthermore, when the SUSM-1/p53 cells were exposed to X-rays, the mutation frequency increased to about twice that of the non-irradiated SUSM-1/p53 cells. However, SUSM-1/p53 cells showed neither anchorage-independent growth in soft agar nor tumorigenicity in nude mice. These results indicate that the mutant p53 gene itself, which generally works in a dominant-negative way on cellular carcinogenesis, is not sufficient for neoplastic transformation of immortalized human cells, and that additional genetic change(s) may be necessary for transformation.

4-Nitroquinoline-1-oxide↗
PubMed1995

The role of prohormone convertases PC1 (PC3) and PC2 in the cell-specific processing of proglucagon.

To elucidate the mechanism of the differential processing of proglucagon, we analyzed the processing products of proglucagon in three types of rodent endocrine cells and their relation to prohormone convertases PC1 (PC3) and PC2. Proglucagon gene was transfected into AtT-20 cells and GH3 cells, which are derived from pituitary tumors. InR1-G9 cells, which are insulinoma-derived cells, express an endogenous proglucagon gene. Oxyntomodulin was the predominant processing product in AtT-20 cells, which contained abundant PC1 mRNA. In contrast, glucagon was the major product in GH3 cells, which expressed PC2 mRNA. Oxyntomodulin and glucagon were produced in equal amounts in InR1-G9 cells, which expressed both PC1 and PC2 mRNAs. These findings suggest that PC1 and PC2 preferentially cleave proglucagon into oxyntomodulin and glucagon, respectively, thus contributing to the cell-specific processing of proglucagon.

Animals↗
PubMed1995

Two-dimensional electrophoretic analysis of down-regulated proteins in human fibroblasts immortalized by treatment with either 4-nitroquinoline 1-oxide or 60Co gamma rays.

Cellular proteins were examined by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) in order to determine the mechanisms of cellular aging and immortalization of human fibroblasts. A total of 10 cell lines were studied, four of which were immortalized. OUMS-24F and SUSM-1 cells were immortalized by repeated treatment with 4-nitroquinoline 1-oxide (4NQO), KMST-6 cells were immortalized by intermittent exposure to 60Co-gamma rays, and IMR-90/SV40 cells were immortalized with simian virus 40 (SV40). None of these immortalized cells were tumorigenic. Four normal human fibroblast cell lines, OUMS-24, AD 387, KMS-6 and IMR-90, and two human cervical cancer cell lines, HeLa and A-431, were also studied. Applying 2-D PAGE, the down-regulation of the identical proteins was observed in the four immortalized cell lines and in the two human cancer cell lines. Their molecular masses were about 80 kDa and the isoelectric points ranged between 5.5 and 6.3. We could not find any information on our proteins from the recent protein data bases. Further characterization of the proteins indicated that they might be phosphorylated cytoskeletal proteins.

4-Nitroquinoline-1-oxide↗
PubMed1995

IDF Member Associations' activities presented in the 15th IDF Congress Exhibition.

IDF Member Associations' activities were presented in the 15th IDF Congress Exhibition held at Port Island, Kobe, Japan from November 7 to November 11, 1994. The purpose of the exhibition was to inform members of the progress on patient education, guidance of diet and exercise treatment, the compliance situation on self-monitoring of blood glucose, self-injection of insulin, etc., in each association. A total of 31 associations including 17 from outside Japan and 14 from Japan participated in this exhibition. An exhibition theme was not designated to foreign associations. However, in order to avoid a similar content of exhibitions from the Japanese associations, a specific theme was assigned to each association. From these exhibitions we can comprehend the present status of the activities of all the diabetic associations in the world. Especially, an enthusiasm for patient and co-medical staff education in each association was clearly recognized. The total number of visitors including the commercial exhibition during the Congress reached about 17000 people.

Diabetes Mellitus↗
PubMed1995

Genetic complementation of the immortal phenotype in group D cell lines by introduction of chromosome 7.

Human immortal cell lines have been classified into at least four (A-D) genetic complementation groups by cell-cell hybrid analysis, i.e., a hybrid derived from different groups becomes mortal. Recently we have demonstrated that introduction of human chromosome 7 suppresses indefinite division potential in the non-tumorigenic human immortalized fibroblast lines KMST-6 and SUSM-1, both assigned to complementation group D. By extending our microcell-mediated chromosome transfer, we found that chromosome 7 also suppresses division potential in the human hepatoma line HepG2 (again, assigned to group D). Chromosome 7 was thus shown to suppress indefinite growth in the above group D cell lines irrespective of their cell types, or whether they are tumorigenic or not. Since chromosome 7 had no such effect on representative cell lines derived from complementation group A, B or C, these results indicate that the senescence gene(s) commonly mutated in the group D cell lines is located on chromosome 7.

Base Sequence↗
PubMed1995

Human fibroblasts (KMST-6/RAS cell line) transformed with 60Co gamma-rays and c-Ha-ras oncogene produce a large amount of granulocyte colony-stimulating factor (G-CSF); production is enhanced by cAMP, theophylline, and butyrate.

Human fibroblasts (KMST-6/RAS cell line), which was malignantly transformed in vitro with 60Co gamma-rays and the c-Ha-ras oncogene, produced a large amount of granulocyte colony-stimulating factor (G-CSF). The production was greater during the logarithmic growth phase than during the stationary phase. cAMP and theophylline, alone or in combination, and butyrate significantly enhanced G-CSF production, but dexamethasone or 5-azacytidine did not. Enhanced production of G-CSF by these agents was regulated at the posttranscriptional level. Neither the expression of the ras oncogene nor the tumorigenicity of the cells correlated with the production of G-CSF.

Butyrates↗
PubMed1995

Karyotypic analysis in the process of immortalization of human cells treated with 4-nitroquinoline 1-oxide.

The establishment of a model system of neoplastic transformation of normal human cells has been attempted with a chemical carcinogen, 4-nitroquinoline 1-oxide (4NQO). In the course of these experiments, it was noticed that immortalization of human cells is a multi-step process involving several mutational genetic events. Thus, chromosomal changes which occurred during the process of immortalization of human fibroblasts were examined. To accomplish immortalization, fibroblasts obtained from an embryo were repeatedly treated with 10(-6) M 4NQO from primary culture to passage 51 (59 treatments in total). Before immortalization, some chromosomes (especially, chromosomes 2, 6, 8, 10, 11, 12, 15, 19, and 20), were lost at a relatively high frequency. After immortalization, the chromosomes distributed so broadly in the triploid to hypotetraploid region without a distinct modal number or without marker chromosomes that it was difficult to identify the specific chromosomes related to the immortalization of human cells. No specific structural chromosomal changes were detected. Although the significance of such chromosome changes in relation to immortalization is not clear, the loss of some specific chromosomes suggests that genes which are involved in cellular aging and which suppress immortalization may have been lost in the immortalization process.

4-Nitroquinoline-1-oxide↗
PubMed1995

[Neoadjuvant chemotherapy with tegafur suppository for rectal cancer--effects of tegafur on nuclear DNA content of cancer cells--Tochigi Colorectal Cancer Study Group].

To assess the significance of neoadjuvant chemotherapy for large bowel cancer, we investigated an effect of tegafur on cancer cell kinetics by DNA content flow cytometric analysis. The pathologic specimens analyzed in this study were obtained from 28 patients with rectal cancer who had received tegafur suppositories prior to surgery. Mean cumulative doses administered were 13.4 g, and mean duration was 12.7 days. In 24 of the 28 specimens, the DNA ploidy and DNA index of the cancer cells were essentially unchanged after the chemotherapy, and DNA aneuploidy was present in 67%. The proportion of cells in S-phase in DNA aneuploid tumors was significantly higher than in DNA diploid tumors. The proportion of cells in G0G1-phase was inversely correlated to that in S-phase. After the chemotherapy, the proportions of cells in S-phase increased both in DNA diploid and aneuploid tumors, although a significantly higher mean value was found only for the latter (p < 0.05). In the DNA aneuploid tumors, there was a higher frequency of responders confirmed by histological evaluation (44%) as compared to the DNA diploid tumors (25%), and a tendency for increases in S-phase fraction of the responders to be greater than in non-responders. These results suggest that DNA flow cytometry-derived parameters may conceivably be useful in predicting the antitumor effect of 5-FU and its derivatives against large bowel cancer.

Aged↗
PubMed1995

[An immunohistochemical study on microtubule associated protein-1 of normal and malignant human gastric tissue].

Microtubule Associated Protein-1 (MAP-1) plays an important role for polymerization of tublin to microtubules. Indirect immunohistochemistry using anti-MAP-1 monoclonal antibody was performed in this study. Difference of internuclear MAP-1 staining patterns between normal and malignant human gastric tissues was investigated. Normal gastric tissue had localized MAP-1 positive staining nucleus in corresponding area of generative cell zone of gastric gland. On the other hand, the 75% cases of gastric cancer showed numerous labeled nuclei in most of the cancer tissues, and 25% cases did not show positive staining of nuclei in cancer tissue. The nuclei staining were classified as negative (-), weak granular (+) and strong punctate (++). The tissue staining pattern was fallen into two patterns, uniform and ununiform stained groups. Positive nuclei staining for MAP-1 and staining pattern had no correlation with histological type of gastric cancer, vessel invasion and lymph node metastasis. But post operative 5-years survival rares were 77.3% in uniform stained group and 30.0% in ununiform stained group. Thus, there were relationship between the post operative survival ratio and the staining pattern of nuclei. Internuclear MAP-1 staining pattern was considered to be one of effective parameters on prognostic sign in gastric cancer.

Antibodies, Monoclonal↗
PubMed1995

Mechanism of antisense effect studied by functionalized oligonucleotides.

In order to study the mechanism of antisense effects, various functional groups such as photocrosslinkers, fluorescent materials, and gold particles were introduced to antisense DNAs. Upon UV-irradiation, the hybrid between DNA and antisense DNA with a photocrosslinker was stabilized. The fluorescence microscopy and transmission electron microscopy (TEM) represented clear images of antisense DNA in the cultured cells. Fluorescent-labeled S-Oligos were recognized in the cytoplasm and especially on certain organs, which are not specified. TEM images of cultured cells treated with gold-conjugated S-Oligo suggested the mechanism of cellular uptake of antisense DNA.

Base Sequence↗
PubMed1994

Molecular cloning of the second major allergen, Cry j II, from Japanese cedar pollen.

Cloning of a cDNA from Cry j II, the second major allergen from Japanese cedar (Cryptomeria japonica) pollen, is described. An isolated Cry j II cDNA contained an open reading frame coding for 514 amino acid residues. The mature Cry j II protein consisted of 388 amino acid residues (R46-S433). According to a homology analysis, no amino acid sequence homology was observed between Cry j II and Cry j I, another major allergen. But Cry j II showed homology with polygalacturonase (PG) derived from tomato (40% identity) at the amino acid level. The sequence information can potentially be used to devise an effective course of immunotherapy for Japanese cedar pollinosis.

Allergens↗
PubMed1994

Enhanced phosphoinositide metabolism in colorectal carcinoma cells derived from familial adenomatous polyposis patients.

The production of the second messenger molecules diacylglycerol and inositol 1,4,5-trisphosphate is mediated by activated phosphatidylinositol-specific phospholipase C (PLC) enzymes. We report the enhancement of the phosphoinositide metabolism pathway in KMS-4 and KMS-8 cells, both of which are human colorectal carcinoma cell lines derived from familial adenomatous polyposis patients. In these cells, the cellular contents of diacylglycerol and inositol 1,4,5-trisphosphate were constitutively increased and the PLC activity in vitro was significantly high, as compared with those in normal colon cells or in other sporadic colorectal carcinoma cells. Northern and Western analyses showed the high expression levels of both PLC-gamma 1 and PLC-delta 1 in KMS-4 and KMS-8 cells. Moreover, we detected the enhancement of protein-tyrosine kinase activity and tyrosine phosphorylation of PLC-gamma 1 in these KMS cells. These results suggest the involvement of activated phosphoinositide signaling pathways in the colorectal tumorigenesis of familial adenomatous polyposis.

Adenocarcinoma↗
PubMed1994

Increase in production of hepatocyte growth factor by human embryonic lung fibroblasts in the process of aging in culture.

It was determined whether human hepatocyte growth factor (hHGF)-producing ability would change in the human embryonic lung fibroblast cell strains (MRC-5 and IMR-90) until the cells senesced in culture. The effects of phorbol 12-myristate 13-acetate (PMA), dexamethasone, and transforming growth factor-beta 1 (TGF-beta 1) on hHGF production were also studied in these cell strains. For stimulation of DNA synthesis of adult rat hepatocytes in primary culture, hHGF secreted by MRC-5 cells at 39.9 and 69.8 population doubling levels (PDLs) showed almost the same activity as recombinant hHGF. Secretion of hHGF by MRC-5 cells increased about threefold between 37.3 and 67.8 PDLs. IMR-90 cells also showed about a threefold increase in hHGF secretion with increased passage from 37.8 to 66.0 PDL. Both cell strains showed almost the same ratio of hHGF amount in the cell extracts to that secreted into the medium around 40 and 70 PDLs. Northern blot analysis showed that the transcriptional level of the hHGF gene in MRC-5 cells increased about three-fold from 42.0 to 73.6 PDL in culture. These findings indicated that hHGF production increased in both cell strains with aging in culture. Production of hHGF in both cell strains was remarkably stimulated by treatment with 10 nM PMA. On the other hand, hHGF production in both cell strains was slightly suppressed by treatment with 1 microM dexamethasone. TGF-beta at a concentration of 5 ng/ml prominently inhibited hHGF production in both cell strains. The response of both cell strains to these regulators for hHGF production was almost the same around 40 and 70 PDLs in culture.

Animals↗
PubMed1994

Effects of glucagon on urinary excretion of urea and on plasma ammonia level in argininosuccinate synthetase deficiency.

Glucagon, a potent inducer of urea cycle enzymes, was administered subcutaneously, at a dose of 0.5 mg once a day, for 7 days to two citrullinemic patients. During this period, plasma NH3 levels in case 1 decreased significantly (P < 0.05 compared to levels before administration) and daily urinary excretion of urea N increased significantly (P < 0.05). For 1 week after the cessation of administration, the daily urinary excretion of urea N was significantly higher than the level before administration (P < 0.05), the plasma citrulline level during glucagon administration was lower than that before administration. In case 2, glucagon administration also decreased the plasma NH3 level (although the decrease was not statistically significant), and significantly increased daily urinary excretion of urea N (P < 0.05 compared to levels before administration). For 1 week after the cessation of glucagon administration the plasma citrulline level was significantly lower than that before administration (P < 0.05). These results indicate that glucagon significantly increases the urinary excretion of urea in the late onset form of argininosuccinate synthetase deficiency and that it may also decrease plasma NH3 levels in some patients with the deficiency.

Adult↗
PubMed1994

Neuroblastoma of parotid gland: report of a case and immunohistochemical characteristics.

A case of a parotid mass in a 2-year-old boy, postoperatively diagnosed as neuroblastoma, a rare tumour not previously reported in the parotid gland is presented. The neoplasm developed within the parotid gland as a painless mass without regional lymphadenopathy. Histopathologically, the tumour showed primitive nerve cells-neuroblasts-with round or oval dark basophilic nuclei and scanty cytoplasm. The cells were arranged in circular rosettes around an eosinophilic mass consisting of very fine filaments originating in the tumour cells or papillary configuration and sometimes scattered in the poorly developed stroma. Immunohistochemical evaluation of the tumour showed a positive immunoreactivity for vimentin, alpha and beta subunits of S-100 protein, neurone-specific enolase (NSE), substance P, met-enkephalin and chromogranin but cytokeratins, desmin, actin, myosin, glial fibrillary acidic protein (GFAP) and calcitonin gene related peptide (CGRP) were negative. The histopathological and immunohistochemical findings conclude a diagnosis of neuroblastoma of the parotid gland.

Child, Preschool↗
PubMed1994

Human fibroblasts (KMST-6/RAS line) transformed with 60Co gamma-rays and c-Ha-ras oncogene constitutively produce a large amount of human granulocyte-colony stimulating factor (G-CSF).

Human fibroblasts (KMST-6/RAS) transformed with 60Co gamma-rays and the Ha-ras oncogene formed tumors in nude mice. These mice showed splenomegaly and an increase in granulocytes in the peripheral blood. There was a direct correlation between tumor size and spleen size. Histologically, prominent proliferation of granulocytes was observed in the enlarged spleen. These findings indicated that KMST-6/RAS cells might have been producing granulocyte colony-stimulating factor (G-CSF) in the nude mice. In fact, in vitro studies demonstrated that the cells produced G-CSF in the culture medium and that production of G-CSF was greater during the logarithmic growth than during the stationary phase. Nearly equal amounts of G-CSF were produced by cells grown in serum-free or 10% serum-supplemented medium. Neither expression of the ras oncogene nor the tumorigenicity of cells correlated with the production of G-CSF. G-CSF production in KMST-6/RAS cells was significantly stimulated by butyrate, but not by dexamethasone or 5-azacytidine.

Animals↗