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Biomedical subjects

T Sekiya

Publications and source records attributed to T Sekiya.

At least 73 records · Page 4Linked to original sources
PubMed1997

Deletion of three distinct regions on chromosome 13q in human non-small-cell lung cancer.

We examined loss of heterozygosity (LOH) at the retinoblastoma susceptibility gene (RB1) locus on chromosome 13q14 in 20 non-small-cell lung cancers (NSCLCs) using polymorphic markers. The expression of RB protein was examined by immunohistochemical analysis of paraffin-embedded specimens of the same tumors. The results revealed that 10 of 16 informative cases showed an LOH at the RB1 locus, whereas only 2 of the 10 tumors lost expression of the RB protein. These 2 tumors had mutations in the remaining RB1 allele. Thus, inactivation of the RB1 gene appears to be involved in a small subset of NSCLCs only. To elucidate the presence of tumor-suppressor genes other than RB1 on 13q, heterozygosity at 15 different loci was investigated. Of 20 tumors analyzed, 15 showed an LOH at least at one locus, and the regions 13q12.1-qter, 13q12.2-14.2 and 13q14.1-q14.3, including the RB1 locus, were deleted in significant numbers of the tumors. Our results suggest that, in addition to the RB1 gene, abnormalities of other tumor-suppressor genes on chromosome 13q are involved in the development of human NSCLCs.

Carcinoma, Non-Small-Cell Lung↗
PubMed1997

A new T-lymphocyte cloning assay for detection of in vivo mutations in the human hypoxanthine-guanine phosphoribosyltransferase gene.

The X-linked hypoxanthine-guanine phosphoribosyl transferase (hprt) gene is a target of analyses of in vivo mutation frequencies in circulating T-lymphocytes. We established a novel, accessory cell-free cloning method of T-lymphocytes with a hprt mutation by a combined use of recombinant interleukin-2, conditioned medium from activating T-lymphocytes and culture plates coated with anti-CD3 monoclonal antibody. Using the method, we examined mutation frequencies of the hprt gene in T-lymphocytes from six healthy individuals, nine patients with colon cancer including two patients from different families with hereditary nonpolyposis colon cancer and six cancer-free relatives of the patients. In six healthy individuals, the mean cloning efficiency and mutation frequency (MF) of the hprt gene in T-lymphocytes were 0.51 +/- 0.28 and 9.4 +/- 7.5 x 10(-6), respectively. These data were similar to the reported values. The mean MFs in the nine colon cancer patients (10.6 +/- 7.3 x 10(-6)) were not significantly different from those of the 12 cancer-free individuals (11.6 +/- 9.4 x 10(6)). The correlation between mutation frequencies and age of the individuals was significant regardless of the presence or absence of cancers. The single-strand conformation polymorphism analyses of nested RT-PCR products of hprt mRNA were done in 33 mutant clones from five members of a family of which MF values were high. All the analyzed mutant clones show a genetic aberration in the coding region of the hprt gene. At least 28 of 33 mutants were independent. Our method provides a new versatile tool for in vivo analysis for mutations of the hprt gene.

Adult↗
PubMed1997

[A case of giant cell-rich gliosarcoma].

We report a case of gliosarcoma with numerous giant cells resembling ganglion cells and having clear nucleoli. A 75-year woman was admitted to our hospital suffering from progressive left hemiparesis and ambulatory disturbance of one week's duration. CT and MRI studies showed ring enhancement on a clear margin mass in the right parieto-occipital lobe. The mass was totally removed macroscopically. Her left hemiparesis had improved and self walk came to be possible. But the tumor was regrowthed during next two months and she died for three months and a week. The gross and microscopic appearances of the tumors showed the double structure. The surface of the tumor was well enhanced and consisted of soft, gray, and easily bleeding tissue. The central core, however, was poorly enhanced and consisted of hard, yellow, non-bleeding tissue. Macroscopically, the central area included numerous giant ganglion-like cells which were negative for GFAP but positive for EMA in the cytoplasm. These giant cells had abundant collagen fibers and were surrounded by such fibers. Microscopic findings of the surrounding area included numerous spindle shaped cells which were positive for GFAP and vimentin. The origins of giant cells or tumor tissues have long been discussed, but no consensus has yet been obtained. Therefore, we speculated as to the origin in our patient based on immunohistochemical study and the findings of electronmicroscopy. We concluded, in sharp contrast to the old theory of one origin, epithelial tissue of a hamartomatous nature existed initially, followed by the growth of malignant tissue of a reactive astrocytic tumor with a sarcomatous component.

Aged↗
PubMed1997

[A simplified method to monitor oculomotor nerve function in midbrain surgery: recordings of compound muscle action potentials by percutaneous superior orbital electrode].

We report a simple and easily-applicable method to intraoperatively monitor the oculomotor nerve and oculomotor nucleus in the brainstem. A needle electrode is inserted into the space just beneath the superior root of the orbit. With this superior orbital electrode, evoked compound muscle action potentials from the superior rectus and the levator palpebrae superioris muscles were recorded. The nuclei for these two muscles are located caudally in the midline of the midbrain. The responses from the superior orbital electrode, therefore, give the surgeons useful intraoperative guidance during surgery for pineal region tumors and midbrain gliomas.

Action Potentials↗
PubMed1996

The chromosomal organization of the human endogenous retrovirus-like sequence HERV-H: clustering of the HERV-H sequences in a 300-kb region close to the GRPR locus on the X chromosome.

Within the haploid genome there are approximately 1,000 copies of the human endogenous retrovirus-like sequence, HERV-H. Although these sequences are scattered throughout the entire genome, in situ hybridization experiments revealed that there are discrete clusters positioned on chromosomes 1 p and 7 q. In this study, we have located three HERV-H sequences which were unexpectedly clustered within a 300-kilobase region close to the GRPR locus on the X chromosome. In previous studies, no clustering of this sequence has been reported at this locus. Our finding demonstrates that, like other repetitive sequences, clustering of HERV-H occurs in the human genome, although these sequences may not always be detected by in situ hybridization methods.

Base Sequence↗
PubMed1996

Isolation of DNA sequences amplified at chromosome 19q13.1-q13.2 including the AKT2 locus in human pancreatic cancer.

In the human pancreatic cancer cell line PANC1, we detected several DNA fragments with abnormally intensified signals by restriction landmark genomic scanning. Major five of these fragments were cloned. All of the cloned fragments were mapped at the 19q13.1-13.2 region where the AKT2 oncogene was located. Southern blotting using the cloned DNA fragments and a fragment of AKT2 cDNA as probes revealed that the AKT2 gene was amplified in 3 of 12 pancreatic cancer cell lines analyzed including PANC1 and in 3 of 20 primary pancreatic cancers. The AKT2 gene was overexpressed in the 3 cell lines with the amplified gene. The results suggest that the AKT2 gene is a candidate oncogene activated by amplification in some human pancreatic cancers.

Base Sequence↗
PubMed1996

Relative ratios of mRNA molecules encoded by genes with homologous sequences using fluorescence-based single-strand conformation polymorphism analysis.

The combination of reverse transcribed (RT)-PCR and fluorescence-based single-strand conformation polymorphism (SSCP) analysis is proposed for the quantitative determination of the ratio of mRNA molecules with homologous sequences. We applied this procedure to lactate dehydrogenase (LDH) subunits A and B. We designed fluorescence labeled common PCR primers in the sequences highly homologous between LDH-A and LDH-B cDNAs and performed RT-PCR-SSCP analysis. When PCR efficiency was almost the same between the different target sequences, analysis of mixtures of known amounts of LDH-A and LDH-B revealed linear and precise proportions of LDH-A mRNA. Template concentrations and PCR cycles did not affect the determination of proportions of LDH-A to total LDH. The present procedure could be easily applied to investigation of expression levels of genes encoding mRNAs with homologous sequences.

Amino Acid Sequence↗
PubMed1996

Chromosomal assignment of human DNA fingerprint sequences by simultaneous hybridization to arbitrarily primed PCR products from human/rodent monochromosome cell hybrids.

We have developed a technique for the simultaneous chromosomal assignment of multiple human DNA sequences from DNA fingerprints obtained by the arbitrarily primed polymerase chain reaction (AP-PCR). Radioactively labeled human AP-PCR products are hybridized to DNA fingerprints generated with the same arbitrary primer from human/rodent monochromosome cell hybrids after electroblotting to a nylon membrane. Human-specific hybridization bands in the human/rodent fingerprints unambiguously determine their chromosome of origin. We named this method simultaneous hybridization of arbitrarily primed PCR DNA fingerprinting products (SHARP). Using this approach, we determined the chromosomal origins of most major bands of human AP-PCR fingerprints obtained with two arbitrary primers. Altogether, the chromosomal localization of near 50 DNA fragments, comprehensive of all human chromosomes except chromosomes 21 and Y, was achieved in this simple manner. Chromosome assignment of fingerprint bands is essential for molecular karyotyping of cancer by AP-PCR DNA fingerprinting. The SHARP method provides a convenient and powerful tool for this purpose.

Animals↗
PubMed1996

Association of CYP1A1 germ line polymorphisms with mutations of the p53 gene in lung cancer.

We reported an association of smoking-induced lung cancer susceptibility with the human cytochrome P450 1A1 (CYP1A1) polymorphisms in our previous studies. To investigate a relationship between genetically determined individual predispositions and mutations of target genes in the early stage of lung carcinogenesis, we examined p53 mutations in relation to germ line polymorphisms of the CYP1A1 and GSTM1 genes, using surgical specimens of 148 non-small cell lung cancer patients who were smokers. The frequency of p53 mutations among heavy smokers was higher than in patients who had never smoked [P < 0.01; odds ratio (OR), 3.74; 95% confidence interval (CI), 1.46-9.56]. By single-strand conformational polymorphism, aberrant migration bands of p53 gene fragments were detected in 56 cases (38%). Smokers with susceptible rare homozygous alleles of either the MspI or Ile-Val polymorphism of the CYP1A1 gene have a 4.5-fold (P < 0.005; OR, 4.48; 95% CI, 1.64-12.26) or 5.5-fold (P < 0.01; OR, 5.52; 95% CI, 1.55-19.64) higher risk of having a mutation of the p53 gene than those with nonsusceptible predominant homozygous alleles of the gene. Non-small cell lung cancer patients with a susceptible CYP1A1 genotype were at remarkably high risk of having a mutation of the p53 gene when the genotype was combined with a deficient genotype, GSTM1(-). However, there was no difference between the types of p53 mutation and genotypes of the drug-metabolizing enzymes. These results showed that CYP1A1 germ line polymorphisms, which were associated with the genetic predisposition for lung cancer, were related to cigarette smoking-associated p53 mutations.

Cytochrome P-450 Enzyme System↗
PubMed1996

Sensitive detection of loss of heterozygosity in the TP53 gene in pancreatic adenocarcinoma by fluorescence-based single-strand conformation polymorphism analysis using blunt-end DNA fragments.

We have developed a fluorescence-based single-strand conformation polymorphism analysis to detect Haelil-sensitive polymorphic sites in intron 1 of the TP53 gene. It is important to treat the PCR products with Klenow fragment to remove a 3'-protruding nucleotide from the amplified DNA fragments added during the reaction in order to obtain a single peak for each allele. A comparison of the signal profiles of two alleles with those of normal heterozygotes by data processing using computer software has enabled sensitive detection of loss of heterozygosity (LOH) from clinical materials with a fraction of tumor cells below 10%. In analysis of 14 pancreatic carcinomas in which the proportion of the tumor cells is usually low due to the abundance of the stromal component, 7 samples (50%) were informative and 5 of the 7 (71.4 %) were positive for LOH at the TP53 locus. This approach would be useful for allelotyping tumors with low cellularity, as well as other clinical samples such as biopsied specimens and paraffin embedded tissues.

Adenocarcinoma↗
PubMed1996

Absence of a mutation of the p21/WAF1 gene in human lung and pancreatic cancers.

The expression of a negative regulator of the cell cycle, p21WAF1 protein, is trans-activated by wild-type p53, but not by the mutant protein. Therefore, mutations of the p53 and WAF1 genes may be complementary. We examined DNAs from 70 human primary lung (63 of NSCLC and 7 of SCLC) and 24 pancreatic cancers (19 primary cancers and 5 cell lines) for mutations of the WAF1 gene. No mutations were detected in any samples examined, regardless of the mutational state of the p53 gene. The results suggested that aberrations of the coding sequence of the WAF1 gene are not associated with carcinogenesis in lung and pancreatic cancers.

Adenocarcinoma↗
PubMed1996

Deletion mapping of chromosome 10 in human glioma.

We analyzed DNAs from 35 gliomas (27 malignant, grades III and IV; 8 less malignant, grades I and II) for loss of heterozygosity (LOH) using microsatellite sequences on chromosome 10 as polymorphic markers. An LOH was found in 8 of 11 (73%) glioblastomas (grade IV) and 4 of 16 (25%) grade III gliomas, but not in the less malignant types. We detected three commonly deleted regions. One was located in a telomeric region of 10p and the others were relatively large regions of 10q. Our results suggested that three putative tumor suppressor genes on chromosome 10 are involved in the malignant progression of gliomas.

Alleles↗
PubMed1996

Detection of microsatellite instability in cancers by arbitrarily primed-PCR fingerprinting using a fluorescently labeled primer (FAP-PCR).

The microsatellite mutator phenotype (MMP), detected as a change in the number of repeating units in hundreds of thousands of microsatellite sequences in the tumor cell genome, underlies the carcinogenesis of a variety of tumors including sporadic and hereditary nonpolyposis colon cancers. This enhanced microsatellite instability was discovered using arbitrarily primed polymerase chain reaction (AP-PCR) fingerprinting of DNA from colon cancers. In this study, we found an arbitrary primer that can amplify multiple DNA fragments containing repeated sequences, including the poly A tracts found in the Alu repeats of the human genome. The combined use of primer labeling with fluorescence and an automated DNA sequencing analysis of AP-PCR products (FAP-PCR) detected alterations in fingerprint bands in all DNA samples previously determined to belong to the MMP. Fluorescent AP-PCR fingerprinting using this single arbitrary primer provides a convenient and efficient method for detecting tumor specific fingerprint alterations that are usually undetectable by conventional fingerprinting.

Blotting, Southern↗
PubMed1996

The effects of race, living standards, and exercise on the degree of motor development: comparison between schoolchildren in the Republic of Honduras and Japan.

To investigate the development of motor ability according to age and physique, a comparison was made among races and/or living standards of schoolchildren in Republic of Honduras, and between Honduran and Japanese schoolchildren. Based on the results of these comparisons, the extent to which exercise contributes to the development of motor ability was examined. Subjects were schoolchildren of typical three races in Honduras: Negroid, Mongoloid (native Indio), and mixed race (Mongoloid, Caucasoid, and Negroid), who attended public elementary schools. For a further comparison, schoolchildren of mixed race attending private schools, whose living standards are thought to be different from children attending public schools, were also selected. Comparing physique among races from the measurement values in the test battery, Negroid group ranked highest followed by the mixed race group and Mongoloid group. The results for the comparison of motor ability were also in the same order. From the viewpoint of living standards, the physique and motor ability of the private school children, who were from wealthy families, was better than that of the public school children. However, when the degrees of motor development were compared using revised values based on age and physique, the differences among groups became smaller, and there was no significant difference between groups in the 50-meter dash or in the standing long jump. However, a comparison with Japanese schoolchildren showed that, even if there was no difference in physique, Japanese schoolchildren were still superior in motor ability. These results suggest that differences in the degree of motor development are mainly due to differences in exercise experience.

Aging↗