Biomedical subjects

G Tamura

Publications and source records attributed to G Tamura.

At least 109 records · Page 6Linked to original sources

PubMed1996

[Microsatellite analysis].

Microsatellites are tandem iterations of simple di-, tri-, or tetranucleotides. They are very useful for the analysis of LOH (loss of heterozygosity) because they are highly polymorphic and interspersed throughout the genome. The microsatellite analysis also allows us to investigate the genetic instability, demonstrated as the expansion or contraction of repeat elements (replication error, RER), which might have resulted from the disruption of mismatch repair genes such as hMSH2 and hMLH1. The microsatellite analysis is a novel tool of genetic analysis which provides valuable information in the field of molecular oncology.

Chromosome Deletion↗

PubMed1996

[The brittle asthmatic and the morning dipper].

The terms 'brittle asthmatic' and 'morning dipper' were first used by Turner-Warwick in 1977. Since then, the issue of brittle asthmatic is that all attempts to stabilize lower readings in peak expiratory flow (PEF) with regular beta 2-agonists, such as slow compound, oral preparations, or combinations with theophylline seem to fail, although they are rapidly reversed by inhaled beta 2-agonists. In brittle asthmatics regularly treated with a long-acting beta 2-agonist and a sustained-release theophylline, an oral cysteinyl leukotriene antagonist, pranlukast, almost completely inhibited a chaotic pattern of PEF readings. Thus, I suggested that the lower readings might depend on a transient release of cysteinyl leukotriene. In addition, I showed that a long-acting beta 2-agonist, tulobuterol tape, significantly improved a morning dip in PEF readings.

Adrenergic beta-Agonists↗

PubMed1995

Microsatellite alterations in adenoma and differentiated adenocarcinoma of the stomach.

In order to elucidate the significance of the adenoma-carcinoma sequence in gastric carcinogenesis from a genetic point of view, we examined microsatellite alterations (replication error and loss of heterozygosity) on chromosomes 2p (D2S123), 3p (D3S1317), 5q (D5S409), 9p (IFNA), and 13q (D13S153) as well as p53 gene mutations in 13 adenomas and 23 differentiated adenocarcinomas including 8 early carcinomas of the stomach. Replication error was detected in only one of the adenomas (8%, 1/13) at the D5S409 locus and in none at the other loci, and loss of heterozygosity was also an infrequent event found in one adenoma (14%, 1/7 informative cases) at D5S409 and in none at the other loci. A p53 gene mutation was detected in one (8%, 1/13) of the adenomas. Thus, microsatellite alterations and p53 gene mutations are rare events in adenomas. In differentiated adenocarcinomas, replication error was detected in 4 (17%, 4/23) at single or multiple loci, and loss of heterozygosity was observed frequently at D3S1317 (25%, 3/12), D5S409 (67%, 6/9), and IFNA (26%, 5/19). Mutations in the p53 gene were detected in 9 (39%, 9/23) of the differentiated adenocarcinomas. Microsatellite alterations on several chromosomes and mutations in the p53 gene were frequent in differentiated adenocarcinomas, even those at an early stage. These results suggest that the adenoma-carcinoma sequence is relatively rare in gastric carcinogenesis, and that the majority of differentiated adenocarcinomas of the stomach may develop through a de novo pathway.

Adenocarcinoma↗

PubMed1995

Frequent microsatellite alterations on chromosome 3p in esophageal squamous cell carcinoma.

By the microsatellite assay, two types of genetic alterations, loss of heterozygosity (LOH) and replication error (RER), were examined using 7 dinucleotide repeat markers [D3S1317 (3p26); CI3-1169 (3p25); CI3-946 (3p25); D3S1255 (3p24.2-25); CI3-771 (3p21.3); CI3-1413 (3p14.1-14.3); and CI3-373 (3p13)] on the short arm of chromosome 3p as well as 3 markers [D2S123 (2p15-16), IFNA (9p22), and D16S408 (16q12.1-13)] on other chromosomes in 35 patients with esophageal squamous cell carcinoma. On 3p, LOH was detected in 34% (12 of 35) and RER was detected in 60% (21 of 35) at single or multiple loci. RER occurred at a similar frequency in all stages and did not correlate with clinicopathological characteristics. On the other hand, LOH at the 3p25 locus was more frequently detected in carcinomas with lymph node metastasis than in those without it (P < 0.05). The incidences of microsatellite alterations were low on the chromosomes other than 3p, except at D2S123, where the incidence of RER was 20%. These findings suggest that RER on 3p is an early event and that a tumor suppressor gene which is involved in the progression of esophageal squamous cell carcinoma may exist near the 3p25 locus.

Base Sequence↗

PubMed1995

The sequential accumulation of genetic alterations characteristic of the colorectal adenoma-carcinoma sequence does not occur between gastric adenoma and adenocarcinoma.

We screened 30 gastric adenomas and 72 gastric adenocarcinomas for four genetic alterations (mutations of the K-ras, APC, and p53 genes and loss of heterozygosity at the DCC genetic locus) which are known to occur during colorectal tumourigenesis. We used polymerase chain reaction (PCR) single-strand conformation polymorphism analysis to detect mutations. Loss of heterozygosity (LOH) at the DCC locus was ascertained directly by performing PCR on the variable number of tandem repeats within the gene. Mutations of the K-ras gene were not detected in any gastric adenoma or carcinoma. APC mutations were detected in 20 per cent (6/30) of the adenomas but in only 1.4 per cent (1/72) of the carcinomas. In contrast, the p53 gene was frequently mutated in carcinomas (35 per cent; 25/72), but not in adenomas. LOH at the DCC locus was a frequent occurrence in carcinomas (58 per cent; 11/19 informative cases) but was infrequent in adenomas (14 per cent; 1/7). Alterations of the p53 and DCC genes occurred frequently both in differentiated and in undifferentiated gastric carcinomas. The considerable differences in the incidences of genetic alterations between gastric adenoma and carcinoma indicate that the sequential development of gastric carcinoma from adenoma is uncommon in gastric carcinogenesis.

Adenocarcinoma↗

PubMed1995

Frequent loss of heterozygosity at the deleted in colorectal carcinoma gene locus and its association with histologic phenotypes in breast carcinoma.

Loss of heterozygosity (LOH) at the deleted in colorectal carcinoma gene (DCC), a tumour suppressor gene that encodes a protein with high homology to the neural cell adhesion molecule, was investigated in 42 surgical specimens of primary breast carcinoma. LOH was analysed in breast carcinoma by amplifying the DNA, spanning a variable number of tandem repeats site and a restriction fragment length polymorphism site within DCC, using the polymerase chain reaction (PCR). Cell sorting was used to enrich carcinoma cells. The expression of the DCC gene was also investigated using a reverse transcription-PCR method followed by Southern blot hybridization. LOH at the DCC locus was detected in 15 (51.7%) of 29 informative cases and 10 of 13 cases having DCC-LOH showed distinct reduction or loss of DCC expression. The DCC-LOH was closely associated with certain histological phenotypes: DCC-LOH was more frequent in scirrhous carcinomas than in solid-tubular ones (P < 0.05), and was also more frequent in carcinomas with infiltration into fat tissue over the mammary gland than in those without infiltration (P < 0.05). DCC-LOH was detected in invasive lobular carcinomas (2/2), but in none of the noninvasive ductal carcinomas (0/2). These observations suggest that malignant histological phenotypes are associated with DCC-LOH.

Alleles↗

PubMed1995

Cloning and sequencing of cellulase cDNA from Aspergillus kawachii and its expression in Saccharomyces cerevisiae.

The cDNA encoding the endo-beta-1,4-glucanase (carboxymethylcellulase; CMCase-I) from Aspergillus kawachii IFO 4308 was cloned. Nucleotide-sequence analysis of the cloned cDNA insert showed a 717-bp open reading frame that encoded a protein of 239 amino-acid residues. The predicted amino-acid sequence of the mature protein had considerable homology with the protein sequence of the FI-CMCase of Aspergillus aculeatus. The cDNA was introduced into Saccharomyces cerevisiae. The expressed enzyme had carboxylmethylcellulase activity, identified by clear zones on a CMC-agar plate after Congo Red staining.

Amino Acid Sequence↗

PubMed1995

Epithelial-cadherin gene is not mutated in ductal carcinomas of the breast.

We investigated mutations of the epithelial (E)-cadherin gene and loss of heterozygosity (LOH) at flanking loci using three microsatellite markers on the long arm of chromosome 16 in 25 ductal carcinomas of the breast. Expression of E-cadherin was also investigated immunohistochemically. No mutations were detected in exons 6 through 9 of the E-cadherin gene. LOH was observed more frequently (42%) at D16S402 (16q-ter) than at D16S421 (16q22.3-q23.1) (17%), which is located near the E-cadherin gene. Expression of E-cadherin was observed at the cell borders in 92% (11/12) of the tumors examined. The absence of mutations in the E-cadherin gene and its conserved expression suggest that inactivation of E-cadherin does not contribute significantly to the invasion or metastatic potential of ductal carcinomas of the breast. Furthermore, the high frequency of LOH at 16q-ter suggests the existence of another tumor suppressor gene which may play a crucial role in the genesis of ductal carcinomas of the breast.

Adenocarcinoma, Scirrhous↗

PubMed1995

Loss of heterozygosity on the short arm of chromosome 9 without p16 gene mutation in gastric carcinomas.

A putative tumor suppressor gene, p16 (MST1; multiple tumor suppressor 1/CDK4I; cyclin-dependent kinase 4 inhibitor), was isolated and mapped on the short arm of chromosome 9 (9p). The significance of p16 mutations in gastric tumorigenesis was examined by assessing p16 mutations as well as loss of heterozygosity (LOH) on 9p in 13 gastric adenomas and 45 adenocarcinomas. LOH on 9p (IFNA; alpha-interferon locus) was detected in 22% (5/23 informative cases) of differentiated adenocarcinomas, 10% (1/10) of undifferentiated carcinomas and none (0/6) of the adenomas. Although we found a sequence polymorphism at the second position of codon 99 (CGC/CAC) of the p16 in one gastric adenoma patient, no somatic mutations were detected in any of the gastric adenomas or adenocarcinomas. These results suggest that p16 mutations probably do not contribute to gastric tumorigenesis. However, these data suggest that another tumor suppressor gene on 9p (near the IFNA locus) may contribute to the progression of differentiated adenocarcinoma of the stomach.

Adenocarcinoma↗

PubMed1995

IL-5, IL-8 and GM-CSF immunostaining of sputum cells in bronchial asthma and chronic bronchitis.

BACKGROUND: Granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin (IL)-5 or IL-8 have been suggested to play an important role in the pathogenesis of eosinophilic airway inflammation in bronchial asthma or neutrophilic airway inflammation in chronic bronchitis, respectively, However, GM-CSF and IL-8 have biological activities to either eosinophils or neutrophils. OBJECTIVE: To investigate the contribution of these cytokines to airway inflammation, we compared the cellular differential and immunolocalization of GM-CSF, IL-5 and IL-8 in sputum cells from patients with bronchial asthma and chronic bronchitis. METHODS: Cytospins of sputum cells from 12 patients with bronchial asthma and 12 with chronic bronchitis were subjected to cellular differential counting and immuno-cytochemistry with anti-human GM-CSF, IL-5 and IL-8 antibody. RESULTS: The predominant cells in bronchial asthma were eosinophils and lymphocytes, while those in chronic bronchitis were neutrophils. All cytokines examined were detected in either bronchial asthma or chronic bronchitis, although the percentage of GM-CSF and Il-5 positive cells in bronchial asthma (53.4 +/- 6.0 [mean +/- SEM]% and 9.7 +/- 2.8%, respectively) was significantly higher than that in chronic bronchitis (11.4 +/- 2.5%; P < 0.001 and 1.7 +/- 0.3%; P < 0.007, respectively). In contrast, the percentage of IL-8 positive cells in chronic bronchitis (23.8 +/- 7.0%) was significantly higher than that in bronchial asthma (7.& +/- 1.9%; P < 0.04). The cells positive for IL-5 were lymphocytes in bronchial asthma and chronic bronchitis. The cells positive for GM-CSF in bronchial asthma were predominantly eosinophils, while those in chronic bronchitis were monocytes/macrophages and neutrophils. In contrast, neutrophils are mainly positive for IL-8 in chronic bronchitis, while monocytes/macrophages and bronchial epithelial cells are positive for IL-8 in bronchial asthma. CONCLUSION: The immunochemical comparison of GM-CSF and IL-8 localization in sputum cells between bronchial asthma/chronic bronchitis suggests the differential regulation and roles of these cytokines in eosinophilic vs neutrophilic airway inflammation, resulting in the development of different types of airway inflammation.

Adult↗

PubMed1995

In situ expression of the cell adhesion molecules in bronchial tissues from asthmatics with air flow limitation: in vivo evidence of VCAM-1/VLA-4 interaction in selective eosinophil infiltration.

Eosinophils play a critical role in the pathogenesis of bronchial asthma by releasing various mediators. To understand the mechanisms of eosinophil migration to the site of inflammation, we examined the expression of adhesion molecules in the bronchial tissues of asthmatic subjects with air flow limitation. By immunohistochemical analysis, Mac-1, LFA-1, and VLA-4 were strongly positive in eosinophils and mononuclear cells infiltrated in the bronchial mucosa and submucosa. Their number was significantly increased compared with those in control tissue. Immunolocalization for ICAM-1, the ligand of Mac-1 and LFA-1, was detected in the endothelial cells of capillaries and venules, in the mononuclear cells in submucosa, and in the basal layer of the epithelium. Endothelial cells in capillaries and venules were also strongly positive for VCAM-1, the ligand of VLA-4. Immunolocalization for E-selectin was detected in some endothelial cells in capillaries and venules in bronchial submucosa, whereas there were very few positive cells in the bronchial tissues from control subjects. In situ hybridization demonstrated ICAM-1 mRNA expression in the endothelial cells and mononuclear cells in bronchial submucosa. Immunoelectron microscopy for ICAM-1, VCAM-1, and E-selectin demonstrated de novo synthesis of these molecules and their expression along the luminal cell membrane of endothelial cells. These results suggested that ICAM-1, VCAM-1, and E-selectin were newly synthesized prior to spontaneous asthma attacks, and that their expression, particularly that of VCAM-1, may play a key role in eosinophil infiltration into the airway.

Adult↗

PubMed1995

Eosinophils as a potential source of platelet-derived growth factor B-chain (PDGF-B) in nasal polyposis and bronchial asthma.

Tissue remodeling in bronchial tissues from asthmatics as well as in nasal polyp (NP) tissues includes sub-basement membrane deposition of collagen, stromal deposition of extracellular matrix protein, and hypertrophy/hyperplasia of airway smooth muscle cells, which are relevant to the cellular and molecular events induced by platelet-derived growth factor (PDGF). Therefore, we investigated the localization of mRNA and protein of PDGF-B chain (PDGF-B) in NP tissues and bronchial tissues from mild and severe asthmatics by in situ hybridization and immunohistochemistry, respectively. Cells expressing PDGF-B mRNA were found in all nine NP tissues and in bronchial tissues from 2 of 6 normal subjects, 2 of 5 mild asthmatics, and all of 6 severe asthmatics examined. The vast majority of cells expressing PDGF-B mRNA were eosinophils in NP (99.7 +/- 0.2%, mean +/- SD) and asthmatic bronchial tissues (75.0 and 77.8% in mild asthma, and 92.7 +/- 8.1% in severe asthma), but no cells expressing PDGF-B mRNA were eosinophils in normal bronchial tissues. The number of cells expressing the gene in severe asthma tissues (122.3 +/- 32.2/mm2) was similar to that in NP tissues (152.8 +/- 73.9/mm2) and greater than that in mild asthma tissues (4.7 +/- 7.6/mm2, P < 0.01), which was not significantly greater than that in normal bronchial tissues (3.4 +/- 5.2/mm2). Furthermore, we detected immunolocalization of PDGF-B in NP tissues and in asthmatic bronchial tissues. The eosinophils purified from peripheral blood were demonstrated to express PDGF-B gene transcript and immunoreactivity after stimulation with A23187.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Cloning and nucleotide sequence of the calmodulin-encoding gene (cmdA) from Aspergillus oryzae.

A cDNA and genomic gene encoding calmodulin were isolated from Aspergillus oryzae using a part of the calmodulin gene from A. nidulans as a hybridization probe. The gene was in a 3.4-kb SphI fragment and Southern-blot analysis of genomic DNA suggested the existence of a single copy of the calmodulin gene in A. oryzae. The nucleotide sequence analysis showed that the gene consists of five introns and six exons. Although the nucleotide sequence homology with that of A. nidulans was not so high (68%), the deduced amino acid sequence was 100% and 84% identical with calmodulin of A. nidulans and chicken, respectively. The cDNA encoding A. oryzae calmodulin was expressed under the control of the GAL1 promoter in the calmodulin null mutant (cmd1) of yeast, Saccharomyces cerevisiae, and could function as a calmodulin gene.

Amino Acid Sequence↗

PubMed1995

Nucleotide sequence and expression of alpha-glucosidase-encoding gene (agdA) from Aspergillus oryzae.

We have isolated an alpha-glucosidase(AGL)-encoding gene (agdA) from Aspergillus oryzae by heterologous hybridization using the corresponding Aspergillus niger gene as a probe. Southern hybridization analysis showed that the agdA gene is on a 5.0-kb ScaI fragment and there is a single copy in the A. oryzae chromosome. Comparison with the A. niger agdA gene indicated that the agdA gene contains three putative introns from 52 to 59 nucleotides long, and that it encodes 985 amino acid residues. The deduced amino acid sequence of A. oryzae AGL is 78% homologous with the A. niger AGL. The high degree of homology with the amino acid sequence bordering the putative catalytic residue of a number of AGL enzymes, and this enzyme suggests that Asp492 is a catalytic residue of A. oryzae AGL. The cloned gene was functional. Transformants of A. oryzae containing multiple copies of the cloned agdA gene showed a 6-16 fold increase in AGL activity. Like the Taka-amylase A and glucoamylase genes of A. oryzae, expression of the agdA gene was induced when maltose was provided as a carbon source, but expression was not induced by glucose. This result suggested that cis-element(s) involved in maltose induction may be also present in the agdA promoter region.

Amino Acid Sequence↗

PubMed1995

Characteristic expression of three amylase-encoding genes, agdA, amyB, and glaA in Aspergillus oryzae transformants containing multiple copies of the agdA gene.

In Aspergillus oryzae wild-type strains, the expression of the agdA gene encoding alpha-glucosidase (AGL) is induced by maltose at the transcriptional level in a similar manner to the amyB gene encoding Takaamylase A (TAA) and the glaA gene encoding glucoamylase (GLA). In A. oryzae transformants containing multiple copies of the agdA gene, a high-level of AGL activity was observed. This was accompanied by a significant reduction in TAA and GLA activities. Moreover, transformants with the highest AGL activity showed the lowest degree of TAA and GLA activities. Northern blot analyses showed that the transcriptional levels of amyB and glaA in the AGL-overproducing transformant were drastically reduced when large amounts of agdA mRNA were detected in maltose-grown mycelia. In addition, the glucose concentration of the maltose-containing medium that was used to grow the AGL-overproducing transformant for RNA extraction was higher than that of the control transformant. These results suggest that the reduced expression of the amyB and glaA genes in the AGL-overproducing transformant was due to either titration of a common regulatory protein(s) involved in maltose induction or carbon catabolite repression.

Amylases↗

PubMed1995

[Retroperitoneal leiomyoma: a case report].

The patient was a 40-year-old woman who was hospitalized for edema of whole body. On admission, ultrasonography, CT scan and MRI revealed bilateral hydronephrosis due to retroperitoneal large tumors. The angiography showed hypervascular tumors in the pelvis. These tumors were surgically removed and the histology was leiomyoma. The retroperitoneal leiomyoma is rare and only 16 cases have been reported in the literature besides our patient.

Adult↗

PubMed1994

Chemosensitivity and perception of dyspnea in patients with a history of near-fatal asthma.

BACKGROUND: Many deaths from attacks of asthma may be preventable. However, the difficulty in preventing fatal attacks is that not all the pathophysiologic risk factors have been identified. METHODS: To examine whether dyspnea and chemosensitivity to hypoxia and hypercapnia are factors in fatal asthma attacks, we studied 11 patients with asthma who had had near-fatal attacks, 11 patients with asthma who had not had near-fatal attacks, and 16 normal subjects. Their respiratory responses to hypoxia and hypercapnia, determined by the standard rebreathing technique while the patients were in remission, were assessed in terms of the slopes of ventilation and airway occlusion pressure as a function of the percentage of arterial oxygen saturation and end-tidal carbon dioxide tension, respectively. The perception of dyspnea was scored on the Borg scale during breathing through inspiratory resistances ranging from 0 to 30.9 cm of water per liter per second. RESULTS: The mean (+/- SD) hypoxic ventilatory response (0.14 +/- 0.12 liter per minute per percent of arterial oxygen saturation) and airway occlusion pressure (0.05 +/- 0.05 cm of water per percent of arterial oxygen saturation) were significantly lower in the patients with near-fatal asthma than in the normal subjects (0.60 +/- 0.35, P < 0.001, and 0.16 +/- 0.08, P < 0.001, respectively) and the patients with asthma who had not had near-fatal attacks (0.46 +/- 0.29, P = 0.003, and 0.15 +/- 0.09, P = 0.004). The Borg score was also significantly lower in the patients with near-fatal asthma than in the normal subjects, and their lower hypoxic response was coupled with a blunted perception of dyspnea. CONCLUSIONS: Reduced chemosensitivity to hypoxia and blunted perception of dyspnea may predispose patients to fatal asthma attacks.

Adult↗

PubMed1994

Aberrations of tumor-suppressor genes (p53, apc, mcc and Rb) in esophageal squamous-cell carcinoma.

Loss of heterozygosity at 4 tumor-suppressor gene loci (p53, apc, mcc and Rb) was investigated using polymerase chain reactions, in 49 esophageal squamous-cell carcinoma specimens from patients who had undergone curative resection. Mutations in the p53 gene within exons 5 to 8 were also examined. LOH was detected in 9 (43%) of 21 p53 genes, 16 (55%) of 29 apc genes, 10 (48%) of 21 mcc genes, and 13 (52%) of 25 Rb genes for which heterozygosity could be determined. Mutations in the p53 gene were detected in 18 (36%) of 49 cases and were significantly more frequent in stage-III tumors and in tumors exhibiting DNA aneuploidy. In 5 cases where heterozygosity could be determined for all the loci, all had 2 or more aberrations. Additionally, a heterozygous deletion of p53 gene was associated with a mutation of the remaining allele in 8 (89%) of 9 cases. Short-term relapse within 3 to 12 months occurred significantly more frequently in patients having tumors with both p53 aberrations (p < 0.05). Thus, aberration of tumor-suppressor genes was a frequent occurrence in esophageal squamous-cell carcinoma and inactivation of the p53 gene may contribute to the progression of this tumor.

Aged↗