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Biomedical subjects

K Sekikawa

Publications and source records attributed to K Sekikawa.

At least 73 records · Page 4Linked to original sources
PubMed1989

[Flow cytometric DNA analysis in colorectal cancer].

Flow cytometric DNA analysis for assessing malignant potential of colorectal carcinoma was investigated by paraffin-embedded materials. Preservation time of paraffin blocks and formalin fixation time of surgical specimens within 14 days do not influence the nuclear DNA content. There was seen a good correlation between the DNA contents of paraffin-embedded and fresh materials obtained from the same surgical specimens. Using deparaffinized tumor specimens, the nuclear DNA content was measured by flow cytometry in 144 patients with primary colorectal cancer, who had been treated from 1971 to 1985. Forty-four percent of colorectal cancer were diploid and 56% were aneuploid. There was no significant correlation between ploidy pattern and clinicopathological factors. However, the patients with aneuploid tumor had a significantly worse survival than those with diploid tumor (Generalized Wilcoxon test, p less than 0.001). The patients with aneuploid seemed to have an unfavorable survival than those with diploid in the same stage, and had a significantly worse survival in each group of negative nodes, P0 and H0. It is concluded, therefore, that the nuclear DNA content of colorectal cancer may be an important prognostic factor, being independent of pathological stage.

Cell Nucleus↗
PubMed1989

[Flow cytometric DNA measurements of thyroid carcinomas].

Flow cytometric DNA analysis has been performed using paraffin-embedded tissue blocks from 121 patients with thyroid carcinoma. The incidence of aneuploidy found in thyroid carcinoma was 9 (7.4%), while 112 (92.6%) were diploid. Aneuploid specimens consisted of 6 papillary, 1 follicular, 1 medullary and 1 undifferentiated carcinoma. Of 4 undifferentiated carcinoma patients who subsequently died, only 1 was aneuploid. The 5- and 7-year survival rate for diploid and aneuploid patients were 94% vs 37%, and 91% vs 37%, with significant differences (p less than 0.01). DNA measurements have been found useful in predicting the survival of aneuploid patients, though there remains some discrepancy between the DNA content and the clinical findings in cases of thyroid carcinoma.

Adenocarcinoma↗
PubMed1989

[DNA analysis by flow cytometry in breast carcinoma].

Using deparaffinized tumor specimens, a flow cytometric DNA analysis was performed in 63 primary breast cancers from patients who were treated from 1976 through 1982. Fourty-three percent of the cases were found to be aneuploid, and 57% were diploid. No trend to increased aneuploid proportion with a more advanced disease was noted. There was no correlation between the level of ploidy and the clinicopathological factors. Aneuploid tumors seem to have a poorer survival, but no significant difference was found between the two patterns of ploidy. Patients with a low S-phase fraction (SPF) had a significantly longer survival than those with a high SPF. A DNA analysis of the tumor cells in breast cancer is felt to be use for a prognostic evaluation.

Aneuploidy↗
PubMed1988

Cooperative regulation of bovine leukaemia virus gene expression by two overlapping open reading frames in the XBL region.

Bovine leukaemia virus (BLV) induces syncytia in productively infected ovine and bovine monolayer cells. Expression of the env gene directly determines the syncytium-forming activity, since the expression of a cloned env gene directed by the simian virus 40 (SV40) early promoter efficiently induced syncytia in transfected ovine embryonic (OE) cells. However a BLV long terminal repeat (LTR)-directed expression plasmid (pLTRenv) failed to induce syncytia in transfected OE cells, suggesting insufficient promoter activity of the LTR sequences. To assess the role of the XBL genes, which are located in the 3' distal region of the genome, in viral gene expression we constructed SV40 early promoter-directed expression plasmids. These contained open reading frames (ORFs) in the XBL region, and were examined for syncytium-inducing activity by cotransfection with pLTRenv. The results suggest that both XBL-I (the longest ORF: x-lor) and XBL-II (a shorter overlapping ORF: x-sor) are trans-acting genes which cooperatively activate LTR-directed viral gene expression.

Amino Acid Sequence↗
PubMed1988

Influence of implantation site on growth, antigen expression and metastatic potential of human colonic cancer HT29 and 5583 xenografts in nude mice.

In order to study the interaction between tumors and host environmental factors, we xenografted cells from the human colonic carcinoma cell lines HT29 and 5583-S in the subcutis, cecum, spleen and liver of nude mice and compared growth characteristics, metastatic potential and some phenotypic features of the xenografts in these sites. No remarkable differences were observed between the tumors at different inoculation sites in regard of their expression of carcinoembryonic antigen and secretory component or type of mucin produced. Also the proportion of DNA synthesizing cells as determined by bromodeoxyuridine incorporation appeared to be comparable in the studied implantation sites. Local invasive growth characteristics and metastatic potential, however, showed marked differences. Subcutaneous and cecal xenografts frequently showed tumor cell invasion into the surrounding tissue, vasoinvasive growth and discontinuous basement membrane deposition, whereas splenic and hepatic implants demonstrated more encapsulation, no invasion of blood vessels and more continuous basement membrane deposition. Subcutaneous xenografts produced no metastasis. With HT29 cells liver and lymph node metastases occurred frequently from the splenic as well as the cecal xenografts. 5583 cells regularly produced liver metastases from the splenic xenografts, whereas no metastasis from cecal xenografts were observed. We conclude that although the patterns of invasive growth and the metastatic potential differ for various implantation sites, antigen expression and cell kinetic features of tumor implants are hardly influenced by the site of inoculation.

Animals↗
PubMed1987

The establishment and characterization of two new cell lines derived from a single human colonic adenocarcinoma.

Two cell lines with different in vitro growth characteristics were established from a single mucinous colonic adenocarcinoma. Epithelial cells of the line 5583-E demonstrated anchorage-dependent growth while those of line 5583-S were anchorage-independent and grew as multicellular floating spheroids. Both cell lines shared common characteristics with respect to the expression of differentiation markers (secretory component, carcinoembryonic antigen), mucins and karyotype (trisomy 12 and 14, marker chromosome) but also showed consistent differences. In nude mice 5583-S cells formed moderately differentiated mucinous adenocarcinomas with high carcinoembryonic antigen and mucin production, whereas 5583-E xenografts were poorly differentiated and almost entirely failed to produce carcinoembryonic antigen and mucins. The plating efficiency of 5583-E cells appeared to be greater and doubling time shorter than those of 5583-S cells. Furthermore, 5583-E cells showed an extra isochromosome, 1q. The cell lines were genotypically and phenotypically stable over a period of 2 years. Our results reemphasize that multiple cell lines with heterogeneous phenotypic and genotypic characteristics can be obtained from a single primary tumor.

Adenocarcinoma, Mucinous↗
PubMed1987

Molecular cloning of infectious proviral genomes of bovine leukemia virus.

Covalently closed circular DNA molecules of bovine leukemia virus were cloned in the lambda phage vector lambda gtWES-lambda B and subsequently in the plasmid vector pUC12. Proviral DNAs of 8.3 kb which have one copy of a long terminal repeat and uniform restriction endonuclease sites were preferentially obtained. Four randomly selected clones were examined for their biological activities by DNA transfection experiments. The ovine embryonic cells transfected with these clones formed syncytia which represent the expression of BLV genes. The infectious virions could be recovered from the transfectants.

Animals↗
PubMed1987

Establishment of bovine leukemia virus-producing and -nonproducing B-lymphoid cell lines and their proviral genomes.

We have established four cell lines in vitro from peripheral leukemic cells of four independent enzootic bovine leukosis (EBL) cattle. All cell lines exhibited differentiated B-cell characters. Two of them produced infectious bovine leukemia virus (BLV), but the others did not. Nonproducer cell lines contained single copies of defective BLV proviral genomes with the same integration profiles as the uncultured cells. On the other hand, numerous proviral copies were detected in producer cell lines. One of the producer cell lines, BL407, whose original uncultured cell contained complete and defective proviral genomes retained the original two copies and had increased only complete genomes in different integration sites after long term culture. These findings suggest that the monoclonal leukemic cells from EBL cases are preferentially established in vitro irrespective of their proviral structures, and the producer B-lymphoid cells amplify their proviral copies by reinfection with viruses re-expressed from the cells during in vitro cultivation.

Animals↗
PubMed1986

[The cancer family syndrome--a case report].

A family diagnosed as cancer family syndrome because endometrial cancer was found in a member of this colorectal cancer-prone family was reported. The fact that uterine (endometrial) cancer was found in a family member during the serial follow-up of this family shows that there is no more than a difference of time between familial colorectal cancer and cancer family syndrome. The clinical significance of the familial cancer aggregation would be an important clue in the early detection of another new cancer in the family.

Adenocarcinoma↗
PubMed1984

[A case of familial breast cancer].

The occurrence of breast cancer in 5 members of a family is reported. No specificity of the location, staging or histological typing of the lesions was observed in these cancers. But the characteristics of "hereditary breast cancer", early onset and the occurrence of metachronous double cancers, were observed. As for heredity, it is suspected to be autosomal dominant trait; on the other hand it is more appropriate to assume a poly genic pattern. Recognizing the importance of familial cancer occurrence, it may be possible to detect early cancerous lesions in family members.

Adult↗
PubMed1983

Defects in functional expression of an influenza virus hemagglutinin lacking the signal peptide sequences.

We have investigated the requirement of the signal sequence for expression of influenza virus hemagglutinin (HA). For this purpose we used a recombinant prepared from a late-region deletion mutant of simian virus 40 (SV40) and cloned influenza HA DNA; the influenza DNA was inserted into the late region of SV40 previously occupied by the deleted sequences coding for SV40 capsid proteins. A simple in-phase deletion was made in the HA DNA, resulting in loss of 11 internal amino acids from the 16 amino acid signal peptide. This deletion HA recombinant was then used to infect African green monkey kidney cells. Mutant HA was not detected on the cell surface but stably accumulated in the cytoplasm at a level similar to that of wild-type HA. NaDodSO4/polyacrylamide gel analysis of lysates from infected cells showed that mutant HA was not glycosylated. Significantly, the amount of mutant HA synthesized was not affected by tunicamycin. In contrast, wild-type HA was decreased more than 90% by tunicamycin. These findings suggest that mutant polypeptide is synthesized on free polyribosomes rather than on membrane-bound polyribosomes. The mutant HA failed to agglutinate erythrocytes, probably due to a defect directly or indirectly associated with the lack of carbohydrate side chains.

Amino Acid Sequence↗
PubMed1981

Isolation and characterization of polyoma host range mutants that replicate in nullipotential embryonal carcinoma cells.

Polyoma wild-type virus replicates in most murine differentiated cells but fails to produce virus in murine embryonal carcinoma cells. Polyoma host range mutants have been isolated that replicate in several nullipotential embryonal carcinoma cell lines but fail to replicate in a pluripotential cell line. The final virus yield of these host range mutants is dependent upon the multiplicity of infection in both differentiated cells and nullipotent embryonal carcinoma cells. Two independently derived host range mutants contain the same single base pair change (A.T to G.C) and a 33- and 67-base pair duplication of those viral DNA sequences containing this point mutation. This duplication of viral DNA is located at 69 map units on the polyoma genome on the late gene side of the origin of viral DNA replication (70.5 map units). This type of mutation suggests several models to explain the polyoma host range restriction in embryonal carcinoma cells.

Animals↗
PubMed1979

Mappings of adenovirus type 7 cytoplasmic RNA species synthesized early in lytically infected cells and synthesized in transformed cells.

Early virus-specific RNA synthesized in KB cells infected with adenovirus type 7 and virus-specific RNA synthesized in rat embryo cells (71JY1-2) transformed by the adenovirus type 7 HindIII-I.J fragment (left-hand 8.1% of the viral genome) have been mapped on the viral genome. About 25% of the viral genome, four discrete regions, two on each strand of the viral genome, are expressed as "early" mRNA. Almost similar regions in the left-hand 8.1% of the viral genome are transcribed both in KB cells at early times after infection and in 71JY1-2 cells.

Adenoviruses, Human↗