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Biomedical subjects

N Kamata

Publications and source records attributed to N Kamata.

At least 73 records · Page 4Linked to original sources
PubMed1986

High incidence of amplification of the epidermal growth factor receptor gene in human squamous carcinoma cell lines.

Southern blot-hybridization analysis of DNAs from human tumors demonstrated amplification of the epidermal growth factor (EGF) receptor gene in 10 of 12 squamous cell carcinoma cell lines tested and in none of 18 tumor cell lines of nonsquamous cell carcinomas. The degree of amplification in the squamous cells varied from 2- to 50-fold relative to the epidermal keratinocyte. Hybridization analysis of the RNA showed that the amplification of the EGF receptor gene is accompanied with an increase of the 5.6 kilobases of EGF receptor mRNA. Scatchard plot analysis and sodium dodecyl sulfate-polyacrylamide gel analysis of the EGF receptor revealed that the synthesis of the EGF receptor is also greater in the cells with amplified EGF receptor gene. In contrast, Southern blot analysis of DNAs of primary tumors showed that incidence of amplification of the EGF receptor gene in squamous cells (1 of 6) was almost as frequent as in nonsquamous cells (1 of 4). These results show that amplification of the EGF receptor gene is commonly found in various tumors. In addition, our data suggest that primary squamous cell carcinomas with amplified EGF receptor gene may readily adapt to growth in tissue culture.

Carcinoma, Squamous Cell↗
PubMed1986

Enhancement by 1 alpha,25-dihydroxyvitamin D3 of chemically induced transformation of BALB 3T3 cells without induction of ornithine decarboxylase or activation of protein kinase C1.

We reported previously that 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3], a hormonally active form of vitamin D3, markedly enhanced methylcholanthrene-induced transformation of BALB 3T3 A31-1-1 cells. When the cells were treated with methylcholanthrene (1 microgram/ml) for 72 h and then with 1 alpha,25(OH)2D3 (5 ng/ml) for 2 wk, the transformation frequency was 1.95 +/- 0.73 (SD) foci/dish in 8 independent experiments, which was about 20 times that in cultures treated with methylcholanthrene only. Even at a physiological concentration in plasma, i.e., 0.05 ng/ml, 1 alpha,25(OH)2D3 enhanced the transformation frequency significantly (P less than 0.001). 1 alpha,25(OH)2D3 was not cytotoxic but slightly inhibited growth of the cells. Cells treated with 1 alpha,25(OH)2D3 were thin and became arranged in a meshwork with wide intercellular spaces. These morphological changes were reversible. 1 alpha,25(OH)2D3 induced DNA synthesis in quiescent BALB 3T3 cells dose and time dependently, but this effect was less than that of 12-O-tetradecanoylphorbol-13-acetate. Unlike 12-O-tetradecanoylphorbol-13-acetate, 1 alpha,25(OH)2D3 did not interfere with the binding of epidermal growth factor or phorbol dibutyrate. 1 alpha,25(OH)2D3 did not induce ornithine decarboxylase. Moreover, it did not activate protein kinase C in quiescent BALB 3T3 cells or this enzyme isolated from mouse brain. BALB 3T3 cells and their transformants contain a specific cytosol receptor for 1 alpha,25(OH)2D3, but the binding sites of the transformants were fewer and had lower affinity than those of untransformed BALB 3T3 cells. These effects of 1 alpha,25(OH)2D3 were specific, because other derivatives of vitamin D3 induced the same effects only at 200 times or more higher concentrations.

Animals↗
PubMed1986

Growth-inhibitory effects of epidermal growth factor and overexpression of its receptors on human squamous cell carcinomas in culture.

The role of epidermal growth factor (EGF) and its receptors in human cancers was studied using 24 human cell cultures including 15 of squamous cell carcinoma (SCC) of the skin, oral cavity, and esophagus. EGF was found to inhibit the growth and colony formation of all the SCC cells at doses that are mitogenic in many other cells, including epidermal keratinocytes and dermal fibroblasts. This inhibitory effect of EGF on SCCs was specific, because EGF did not inhibit and in some cases slightly stimulated the growth of other tumor cells, such as adenocarcinomas of the stomach, cervix, and breast and sarcomas. The amounts of EGF receptors on these SCC cells were measured by immunoprecipitation of labeled proteins with anti-EGF receptor polyclonal antibody and binding assay of membrane preparations using 125I-EGF. Of 13 SCC cell cultures tested, all except 3 of esophageal SCC showed higher levels of EGF receptor than normal epidermal keratinocytes, which contain 1.5 X 10(5) binding sites/cell. In general, SCCs of the skin and oral cavity had large amounts of EGF receptor on the order of 10(6)/cell, whereas the receptor of esophageal SCCs was on the order of 10(5)/cell. Some SCC cells had about twice as many EGF receptors as A431 cells. The values for the equilibrium dissociation constant (Kd) of these cells were on the order of nM. The sensitivity to the inhibitory effect of EGF correlated well with the elevated level of EGF receptors in 12 SCC cell lines, and higher significance was obtained when data on esophageal SCCs were excluded. The present observations suggest that EGF and EGF receptors play a role in the development of SCCs.

Carcinoma, Squamous Cell↗
PubMed1986

[Time course of NMR images and T1 values associated with hypertensive intracerebral hematoma].

The present study describes time courses in tissue T1 values, as well as in NMR imagings, associated with hypertensive intracerebral hematoma (ICH). Non-operative 21 cases of ICH were examined by FONAR QED 80-alpha NMR system, which possessed dual modes of image display and focal T1 measurement (static magnetic field: 433 gauss). As the first step of examination SSFP images are displayed and then, at the regions of interest, absolute values of T1 are measured by field focusing technique. The extent of ICH was revealed as high density zone in NMR imaging, occasionally represented much wider extent of high density area than the finding on X-ray CT. Prolonged T1 values were obtained from such high density zone. This wide-spread high density area was regarded to reflect the spread of perifocal brain edema. T1 value of the hematoma itself was rather shortened in its initial phase within 2 weeks, thereafter followed by prolongation in the time lapse. This seemed to reflect the alterations in the properties of hematoma such as clot formation in earlier phase and resolution in later phase. On the contrary, T1 in the brain tissue surrounded to hematoma was apparently prolonged in the early phase within 2 weeks, representing the maximal values of 312 msec around 2 to 4 weeks after the onset, and then gradually normalized in the period over 1 month. This alteration in tissue T1 likely represents the processes of edema formation and its regression in perifocal zone. T1 values measured in perifocal region might be available for the evaluation of edema state in association with cerebrovascular accident.

Adult↗
PubMed1985

A v-erbB-related protooncogene, c-erbB-2, is distinct from the c-erbB-1/epidermal growth factor-receptor gene and is amplified in a human salivary gland adenocarcinoma.

From a human genomic library, we obtained six v-erbB-related DNA clones. A DNA probe prepared from one of the clones, lambda 107, hybridized to EcoRI fragments of 6.4 and 13 kilobase pairs of human DNA. Neither of these fragments was amplified in A431 vulva carcinoma cells, in which the gene encoding the epidermal growth factor receptor is amplified. In addition, the probe from lambda 107 hybridized with a single, 4.8-kilobase poly(A)+ RNA species and did not react with EGF receptor mRNA. Thus, we conclude that clone lambda 107 represents a v-erbB-related gene (c-erbB-2) that is distinct from the EGF receptor gene. In contrast, the other five clones were shown to represent the EGF receptor gene (c-erbB-1). Partial nucleotide sequence analysis of the lambda 107 insert showed that this clone contained at least seven putative exons and that six of them could encode the kinase domain characteristic of protein products of the src oncogene family. Southern blot analysis showed close similarity of the restriction patterns of the rat c-erbB-2 gene and the rat neu oncogene, suggesting possible involvement of c-erbB-2 in human cancer. In fact, approximately 30-fold amplification of c-erbB-2 was observed in a human adenocarcinoma of the salivary gland.

Adenocarcinoma↗
PubMed1984

Pluridirectional macrotomography with three-fold magnification. An assessment of image quality and clinical application.

The purpose of this paper is to present the possible usefulness of macrotomography with three-fold magnification as demonstrated by a new apparatus. It can perform both conventional tomography and macrotomography of the same object plane. Quantitative evaluation included measurements of resolution, modulation transfer function and radiation dose. Qualitative evaluation included an analysis of clinical cases in which both techniques were used. The superior image quality of macrotomography with three-fold magnification was demonstrated and the clinical areas in which it proved most helpful are defined.

Humans↗
PubMed1982

Human renal cell carcinoma: establishment and characterization of two new cell lines.

Characterization studies have been carried out on 2 cell lines (KPK 1 and KPK 13) established from human renal adenocarcinoma. KPK 1 and KPK 13 have been passaged 178 times in vitro for about 6 years and 7 months and 78 times for about 3 years an 2 months, respectively. Although morphologic differences exist between the 2 lines, each has an epithelial morphology and exhibits multilayering. Doubling time of KPK 1 and KPK 13 cells was 29 hours and 51 hours, respectively. Both KPK 1 and KPK 13 induced tumors at the site of subcutaneous injection, closely resembling the original tumor from which they were derived. Chromosome number of both cell lines was 100 per cent aneuploid and the presence of Y chromosomes was confirmed by G banding in KPK 13 cells. KPK 1 was found to have high thromboplastic and high fibrinolytic activities, whereas KPK 13 was shown to have comparatively low thromboplastic and no detectable fibrinolytic activities. These activities were detected in the serum free supernatant fraction from KPK 1 cells but were not detected in that from KPK 13 cells.

Adenocarcinoma↗