Search PubMed⌕ Search

Biomedical subjects

K Hiyama

Publications and source records attributed to K Hiyama.

At least 73 records · Page 4Linked to original sources
PubMed1995

Telomerase activity in gastric cancer.

Although many genetic alterations have been reported in gastric cancer, it is not known whether all gastric tumors are capable of indefinite proliferative potential, e.g., immortality. The expression of telomerase and stabilization of telomeres are concomitant with the attainment of immortality in tumor cells; thus, the measurement of telomerase activity in clinically obtained tumor samples may provide important information useful both as a diagnostic marker to detect immortal cancer cells in clinical materials and as a prognostic indicator of patient outcome. Telomerase activity was analyzed in 66 primary gastric cancers with the use of a PCR-based assay. The majority of tumors (85%) displayed telomerase activity, but telomerase was undetectable in 10 tumors (15%), 8 of which were early stage tumors. Most of the tumors with telomerase activity were large and of advanced stages, including metastases. Survival rate of patients of tumors with detectable telomerase activity was significantly shorter than that of those without telomerase activity. Alterations of telomere length (reduced/elongated terminal restriction fragments) were detected in 14 of 66 (21%) gastric cancers, and all 14 had telomerase activity. Cellular DNA contents revealed that all 22 aneuploid tumors had detectable telomerase activity. The present results indicate that telomerase activation may be required as a critical step in the multigenetic process of tumorigenesis, and that telomerase is frequently but not always activated as a late event in gastric cancer progression.

Base Sequence↗
PubMed1995

Telomerase activity in small-cell and non-small-cell lung cancers.

BACKGROUND: Telomerase is an enzyme that adds hexameric TTAGGG nucleotide repeats onto the ends of vertebrate chromosomal DNAs (i.e., telomeres) to compensate for losses that occur with each round of DNA replication. Somatic cells do not have telomerase activity and stop dividing when the telomeric ends of at least some chromosomes have been shortened to a critical length. It has been suggested that immortalized cells (including some, but probably not all, cancer cells) continue to proliferate indefinitely because they express telomerase. PURPOSE: To investigate whether expression of telomerase is a prerequisite for the development of naturally occurring human cancers, we assayed the levels of telomerase activity in specimens of human lung tumor and adjacent normal tissue. METHODS: Using a polymerase chain reaction-based assay, we examined telomerase activity in 136 primary lung cancer tissues and 68 adjacent noncancerous tissues obtained by surgical resection. We also studied telomerase activity in four primary and 23 metastatic lesions obtained through biopsy, (two patients) or autopsy (10 patients). Relative telomerase activity levels were estimated by serial dilutions of extracts prepared from the specimens. Telomerase activity was also assayed in extracts of cells present in pleural fluids from three patients with adenocarcinoma of the lung. RESULTS: Among surgically resected samples, telomerase activity was detected in 109 (80.1%) of 136 primary lung cancer tissues and in three (4.4%) of 68 normal adjacent tissues. All 11 surgically resected specimens of primary small-cell lung cancer (from 11 patients) revealed high levels of telomerase activity, whereas the activity ranged from undetectable to high levels in the 125 surgically resected specimens of primary non-small-cell lung cancer tissue (from 125 patients). Generally, high levels of telomerase activity were observed in metastatic lesions and tumors with altered telomere length. A few primary and, surprisingly, some metastatic tumors did not appear to have detectable telomerase activity. Telomerase activity was, however, detected in cells present in all tested pleural fluids obtained (from three patients with adenocarcinoma of the lung). CONCLUSION: The subset of non-small-cell lung cancers that exhibits only low or undetectable levels of telomerase activity may contain primarily mortal cancer cells. Cancers that exhibit high levels of telomerase activity, such as all of the small-cell lung cancers examined in this study, are likely to consist mainly of immortal cells. IMPLICATIONS: Telomerase activity may be useful both as a diagnostic marker to detect the existence of immortal lung cancer cells in clinical materials and as a target for therapeutic intervention.

Base Sequence↗
PubMed1995

Alterations in telomeric repeat length in lung cancer are associated with loss of heterozygosity in p53 and Rb.

In the two-stage model of controlling cellular senescence in cultured human fibroblasts, retinoblastoma (Rb) and p53 proteins may be key factors regulating the mortality stage 1 mechanism. In addition, the critical loss of telomeric DNA due to the end-replication problem may result in the mortality stage 2 mechanism. Cells which acquire telomerase activity can overcome the M2 mechanism by stabilizing telomere length and thus become immortal (telomere hypothesis). At present it is known whether cellular immortality is a prerequisite for all human cancers. To investigate this question and the applicability of the two-stage model to human cancers, we analysed the relationship between alterations of telomere length and other genetic changes in lung cancer. Among 60 primary lung cancer tissues, telomere length alterations were observed in 16 tumors (26.7%) including 14 with short and two with elongated telomeres. Ten of them revealed allelic loss of both p53 and Rb genes, and remaining six showed no abnormalities in both genes. We propose that inactivation of both p53 and Rb genes may promote cell divisions causing telomere shortening in lung cancer as in the two-stage model, while there may be another pathway to overcome both M1 and M2 mechanisms, especially for adenocarcinoma.

Base Sequence↗
PubMed1995

Intracerebral ring-enhancing lesions in a patient with multiple sclerosis: a case report.

BACKGROUND Intracerebral cystic lesions can easily be identified by computed tomography (CT) and magnetic resonance imaging (MRI). Cystic gliomas, brain abscesses, or metastatic carcinoma are the usual underlying causes for this neuroradiologic finding. CASE PRESENTATION We report here the case of a patient with multiple sclerosis who has two intracerebral cystic lesions. CONCLUSIONS Central nervous system (CNS) tissue destruction, necrosis, and cyst formation are very unusual in multiple sclerosis. Diagnostic difficulty therefore arises when patients suspected of having multiple sclerosis have radiologic evidence of cystic CNS lesions.

Adolescent↗
PubMed1995

Correlating telomerase activity levels with human neuroblastoma outcomes.

Telomerase activity was analysed in 100 neuroblastoma cases. Although telomerase activity was not detected in normal adrenal tissues or benign ganglioneuromas, almost all neuroblastomas (94%) did express it, suggesting an important role for telomerase in neuroblastoma development. Neuroblastomas with high telomerase activity had other genetic changes (for example, N-myc amplification) and an unfavourable prognosis, whereas tumours with low telomerase activity were devoid of such genetic alterations and were associated with a favourable prognosis. Three neuroblastomas lacking telomerase activity regressed (stage IVS). Thus telomerase expression may be required as a critical step in the multigenetic process of tumorigenesis, and two different pathways may exist for the development of neuroblastoma.

Adrenal Gland Neoplasms↗
PubMed1995

Lack of effects of atomic bomb radiation on genetic instability of tandem-repetitive elements in human germ cells.

In a pilot study to detect the potential effects of atomic bomb radiation on germ-line instability, we screened 64 children from 50 exposed families and 60 from 50 control families for mutations at six minisatellite loci by using Southern blot analysis with Pc-1, lambda TM-18, ChdTC-15, p lambda 3, lambda MS-1, and CEB-1 probes. In the exposed families, one or both parents received a radiation dose > 0.01 Sv. Among the 64 children, only one child had parents who were both exposed. Thus, of a total of 128 gametes that produced the 64 children, 65 gametes were derived from exposed parents and 63 were from unexposed parents, the latter being included in a group of 183 unexposed gametes used for calculating mutation rates. The average parental gonadal dose for the 65 gametes was 1.9 Sv. We detected a total of 28 mutations at the p lambda g3, lambda MS-1, and CEB-1 loci, but no mutations at the Pc-1, lambda TM-18, and ChdTC-15 loci. We detected 6 mutations in 390 alleles of the 65 exposed gametes and 22 mutations in 1098 alleles of the 183 gametes from the unexposed parents. The mean mutation rate per locus per gamete in these six minisatellite loci was 1.5% in the exposed parents and 2.0% in the unexposed parents. We observed no significant difference in mutation rates in the children of the exposed and the unexposed parents (P = .37, Fisher's exact probability test).

Chromosome Mapping↗
PubMed1995

[Pulmonary manifestation of collagen vascular diseases: role of cytokines in interstitial pneumonia associated with collagen vascular diseases].

Although the pathological patterns of interstitial pneumonia associated with collagen vascular disease (CVD-IP) resemble those of usual interstitial pneumonia in idiopathic interstitial pneumonia (IIP), the clinical features of CVD-IP and IIIP are quite different. We evaluated the differences between these conditions, with regard to the expression of genes in cells obtained by bronchoalveolar lavage. The reverse transcription-polymerase chain reaction was used to measure the levels of mRNA for IL-1 beta, TNF-alpha, IL-8, TGF-beta, PDGF-B, and IGF-1, and no significant differences were found between patients with CVD-IP and those with IIP. However, differential display analysis revealed a fragment that can be considered to have been derived from an unknown gene mRNA, and this was found only in patients with pulmonary fibrosis associated with progressive systemic sclerosis. Expression of specific genes may differentiate CVD-IP from IIP.

Adult↗
PubMed1994

Poor outcome in patients with advanced stage neuroblastoma and coincident opsomyoclonus syndrome.

BACKGROUND: Most patients with neuroblastoma who present with opsomyoclonus have a good prognosis. Neuroblastomas from such patients have been reported to contain a single copy of the N-myc gene. The authors describe three cases of patients with advanced neuroblastoma with opsomyoclonus, which had poor outcomes despite multimodal therapy. METHODS: Amplification and expression of the N-myc gene were examined in these three primary tumors using Southern and Northern blot analyses. Then, flow cytometric analysis of the cellular DNA contents of these tumors was performed. RESULTS: N-myc amplification was observed in two tumors and N-myc RNA overexpression was observed in all three. Analysis of the cellular DNA contents of the tissue specimens revealed hyperdiploidy in all three tumors; one had a triploid index and the other two had hypotetraploid indexes. CONCLUSIONS: These findings suggest that a poor outcome for patients with opsomyoclonus may be associated with N-myc gene activation (amplification and/or overexpression) and that a hyperdiploid tumor is not always associated with a good prognosis.

Adrenal Gland Neoplasms↗
PubMed1994

Alteration in length of telomeric repeats in lung cancer.

We investigated the relationship between telomere length and various characteristics of tumor cells in 46 lung cancer specimens (40 primary lesions and six metastatic lesions). Three variant patterns of telomere length were observed in 16 cases (34.8%): reduction in 13 cases, elongation in two cases, and convergence in one case. These variant patterns were frequently observed in small cell carcinomas, in metastatic lesions, and in cases which possessed the S-type allele of the L-myc gene. All three cases with telomere elongation or convergence were associated with a poor prognosis. This is compatible with the previous report suggesting that telomerase activity may be an indicator of immortality in vitro. In adenocarcinoma, telomere reduction or elongation was also observed in the early stages with a low percentage of cells in the S-phase, while in cases with other histologic types, these changes were observed only in late stage, in metastatic lesions, or in cancerous tissues with a high percentage of cells in the S-phase. Although the reduction of telomere length in these tissues may be a result of many cell divisions, it may represent another stage of carcinogenesis in early-stage adenocarcinoma.

Aged↗
PubMed1994

Prognostic significance of p53 and ras gene abnormalities in lung adenocarcinoma patients with stage I disease after curative resection.

We investigated the prognostic significance of p53 gene abnormalities and ras gene mutations in patients with curatively resected stage I lung adenocarcinoma. Formalin-fixed and paraffin-embedded tissues were obtained from 30 patients who had undergone curative resection for stage I lung adenocarcinoma. Abnormalities of the p53 gene were detected using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis and immunohistochemistry and ras mutations were detected using PCR-restriction fragment length polymorphism (RFLP) analysis. Both univariate and multivariate analyses were performed to assess the relationship between the presence of abnormalities of these genes and the patients' disease-free survival. Eleven tumors (37%) had mutated p53 sequences and 11 (37%) showed p53 overexpression. A total of 15 tumors (50%) had p53 gene abnormalities and the concordance rate was 73%. Seven tumors (23%) showed mutated ras sequences. The univariate analysis revealed that the disease-free survival of patients with any p53 abnormality was shorter than that of those without abnormalities (P = 0.02, generalized Wilcoxon test), and survival of those with p53 protein overexpression was more significantly shorter (P = 0.003, generalized Wilcoxon test). Multivariate analysis using the Cox proportional hazards model indicated that the presence of p53 abnormalities was a significantly (P = 0.01) unfavorable prognostic factor. There was no significant correlation between the presence of ras mutation and survival. These results suggest that analysis of the p53 gene may be helpful for the selection of high-risk patients for clinical trials of adjuvant therapy for stage I lung adenocarcinoma.

Adenocarcinoma↗
PubMed1993

Duplication detection in Japanese Duchenne muscular dystrophy patients and identification of carriers with partial gene deletions using pulsed-field gel electrophoresis.

DNA samples from 21 unrelated Japanese patients with Duchenne muscular dystrophy (DMD) with nondeletion-type abnormality in the dystrophin gene and three samples from possible deletion carriers were analyzed using pulsed-field gel electrophoresis (PFGE). Among the 21 patients, 7 were found to carry partial duplications of the dystrophin gene spanning 50-400 kb. Of these 7 patients, 4 carried duplications corresponding to the major hot-spot regions for deletions (7.5-8.5 kb from the 5' end of cDNA), whereas two cases contained duplications in a region about 10 kb from the 5' end of cDNA, where causative mutations are reported to be rare. Only 1 case was found to contain a duplication of a region about 1 kb from the 5' end of cDNA, which is the reported duplication prone region. A combination of Southern blot analyses of conventional agarose gel electrophoresis and PFGE was confirmed to be useful, not only for detecting duplications and deletions, per se, but also for identifying carriers in the affected family.

Blotting, Southern↗
PubMed1993

Detection of partial deletion and partial duplication of dystrophin gene in Japanese patients with Duchenne or Becker muscular dystrophy.

The dystrophin gene was analyzed in 59 Japanese patients with Duchenne muscular dystrophy (DMD) from 48 unrelated families, including 11 pairs of siblings, and three patients with Becker muscular dystrophy (BMD) from two unrelated families, including one pair of siblings. The relationship between the type of gene abnormality and clinical symptoms was examined. Twenty-seven of 50 (54.0%) unrelated DMD or BMD patients were found to have partial deletions, and five (10%) appeared to have partial duplications in the dystrophin gene. Nine DMD patients, including three pairs of siblings, showed mental retardation, the existence of which was coincident in each pair of siblings, but deletion of an identical exon was not always related to mental retardation in unrelated patients.

Adolescent↗
PubMed1993

Rapid detection and identification of mycobacteria in sputum samples by nested polymerase chain reaction and restriction fragment length polymorphisms of dnaJ heat shock protein gene.

In the diagnosis of mycobacterial infection, more than 4-8 weeks is required to identify the species of mycobacterium responsible for an infection. Therefore, the development of a method for the rapid detection and identification of mycobacteria is necessary for selecting an optimal therapeutic plan early in the patient's course. For this purpose, we developed a method combining a nested polymerase chain reaction (nested PCR) procedure and a restriction fragment length polymorphisms (RFLP) analysis of the dnaJ gene of mycobacteria, which codes for a heat shock protein. The PCR procedure allowed the sensitive detection of mycobacterial DNA in clinical samples. Using only 10 femtograms of mycobacterial DNA as a reaction mixture, a detectable band of target DNA segments could be yielded on an agarose gel. This indicates that even with a single genome amount, the PCR is able to detect mycobacteria. The RFLP analysis of the PCR products allowed us rapidly to distinguish the strains belonging to the M.tuberculosis complex from 11 different strains of nontuberculous mycobacteria. Within 2 days, the method is able to identify the mycobacterial species present in the sputum. Moreover, it has the advantage of not requiring the use of radioisotopes, which strongly enhances its clinical usefulness.

Bacteriological Techniques↗
PubMed1993

Variations among Japanese of the factor IX gene (F9) detected by PCR-denaturing gradient gel electrophoresis.

In the course of feasibility studies to examine the efficiencies and practicalities of various techniques for screening for genetic variations, the human coagulation factor IX (F9) genes of 63 Japanese families were examined by PCR-denaturing gradient gel electrophoresis (PCR-DGGE). Four target sequences with lengths of 983-2,891 bp from the F9 genes of 126 unrelated individuals from Hiroshima and their 100 children were amplified by PCR, digested with restriction enzymes to approximately 500-bp fragments, and examined by DGGE--a total of 6,724 bp being examined per individual. GC-rich sequences (GC-clamps) of 40 bp were attached to both ends of the target sequences, as far as was feasible. Eleven types of new nucleotide substitutions were detected in the population, none of which produced RFLPs or caused hemophilia B. By examining two target sequences in a single lane, approximately 8,000 bp in a diploid individual could be examined. This approach is very effective for the detection of variations in DNA and is applicable to large-scale population studies.

Base Sequence↗