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Biomedical subjects

K Hamada

Publications and source records attributed to K Hamada.

At least 145 records · Page 8Linked to original sources
PubMed1999

Prognostic significance of allelic imbalances on chromosome 9p in stage I non-small cell lung carcinoma.

Loss of heterozygosity (LOH) on chromosomes 2q, 9p, 18q, and 22q frequently occurs in advanced non-small cell lung carcinoma (NSCLC). The association of p53 mutations with prognosis is still unclear in NSCLC. Therefore, we investigated the prognostic significance of allelic imbalances (AI) on these chromosomes and p53 mutations in 108 cases of stage I NSCLC by PCR amplification of polymorphic dinucleotide repeat-containing sequences and PCR-single strand conformation polymorphism analysis. AI on 2q, 9p, 18q, and 22q was detected in 22, 38, 29, and 15% of cases, respectively, whereas p53 was mutated in 41% of stage I NSCLC. AI on 9p and 22q and p53 mutations were significantly associated with shortened survival of the patients (P = 0.010, 0.024, and 0.022, respectively). Although gender and smoking history showed more significant associations with prognosis than other clinicopathological and molecular parameters, independent prognostic significance for AI on 9p was observed (P = 0.002) in male patients with a positive smoking history. These results indicate that clinical aggressiveness of early-stage NSCLC can be partly defined by the presence of AI on chromosome 9p in cancer cells, and that AI on 9p could be a clinically useful prognostic indicator for early-stage NSCLC patients.

Adult↗
PubMed1999

[A case of common variable immunodeficiency that responded to long-term erythromycin chemotherapy].

A 32-year-old woman with common variable immunodeficiency (CVID) accompanied by sinopulmonary infection was evaluated for purulent sputum, cough, and nasal obstruction that did not respond to regular intravenous immunoglobin (IVIG) infusion. Chest X-ray films revealed bronchiectasis affecting both lung bases, and a bacteriological examination of sputum was positive for Pseudomonas aeruginosa. Long-term chemotherapy with erythromycin (EM) was started, and the patient's respiratory symptoms gradually subsided. Sinopulmonary infection is the dominant clinical complication in patients with CVID. This case suggested that long-term EM chemotherapy is useful for the treatment of IVIG-refractory sinopulmonary infection associated with CVID.

Adult↗
PubMed1999

Hospital-based historical cohort study of 234 histologically proven Japanese patients with IPF.

BACKGROUND AND AIM OF THE WORK: Variable clinical courses have been recognized in patients with idiopathic pulmonary fibrosis (IPF), but the disease is known to have a fundamentally unfavorable outcome. In addition, we have yet to fully understand whether the regional or population differences are negligible or not. Therefore, we analyzed the clinical outcomes in Japanese IPF patients in a hospital-based historical cohort study. METHODS: A questionnaire was used to collect records for retrospective analysis of the IPF patients. We analyzed data collected from 51 hospitals and clinics in Japan on 234 Japanese IPF patients (males 170, females 64) with IPF who had been followed up after diagnosis. RESULTS: 1. Five and ten years after the detection of exertional dyspnea, the overall survival rates were 41.0% and 20.1%, respectively. A higher age at the time of detection (over 59) was related to a decrease in survival rates. 2. The incidence of complications was no higher in the corticosteroid-treated cases than in the untreated cases. The effects of corticosteroid treatment on survival was not confirmed in this type of study. CONCLUSIONS: The survival rates of histologically proven Japanese patients with IPF were similar to the rates previously reported in different populations. Age at the detection of exertional dyspnea was critical in terms of the survival rate.

Adrenal Cortex Hormones↗
PubMed1999

Bone mineral density and vitamin D in patients with sarcoidosis.

BACKGROUND AND AIM OF THE WORK: Imbalance of calcium homeostasis has ben frequently detected in sarcoidosis patients. In our previous study abnormal metabolism of calcium was detected in about 40% of the patients. In the current study, bone mineral density (BMD) was investigated in relation to serum concentration of calcium and vitamin D. METHODS: Consecutive groups of fifteen men (40 +/- 12 years, as mean +/- SD) and 18 women (51 +/- 11 years) with histologically proven sarcoidosis who had not been treated with corticosteroids prior to the study were studied together with control groups. BMD was measured with dual-energy X-ray absorptiometry (DXA) of lumbar vertebrae, and the Z score was calculated to avoid bias of sex and age. Serum concentrations of ionized calcium (s Ca2+), 1,25-Dihydroxyvitamin D (s1, 25(OH)2D3) and osteocalcin (sOC) were measured at the same time. RESULTS: In women with sarcoidosis only, sCa2+ and s1,25(OH)2D3 showed inverse correlations with Z score of BMD (r = 0.482, p < 0.05 and r = -0.635, p < 0.01, respectively), and s1,25(OH)2D3 showed a positive correlation with sOC (r = 0.658, p < 0.01). Multiple regression analysis showed that age and s1,25(OH)2D3 were the contributory factors to BMD in female patients. Such a significant correlation was not observed in men with sarcoidosis or controls. CONCLUSIONS: 1,25(OH)2D3 seemed to be contributory to accelerated turnover of the bone and reduction of BMD in women with sarcoidosis.

Absorptiometry, Photon↗
PubMed1998

Amino acid sequence requirement for efficient incorporation of glycosylphosphatidylinositol-associated proteins into the cell wall of Saccharomyces cerevisiae.

During cell wall biogenesis in Saccharomyces cerevisiae, some glycosylphosphatidylinositol (GPI)-attached proteins are detached from GPI moieties and bound to beta-1,6-glucan of the cell wall. The amino acid sequence requirement for the incorporation of GPI-attached proteins into the cell wall was studied by using reporter fusion proteins. Only the short omega-minus region composed of five amino acids, which is located upstream of the omega site for GPI attachment, determined the cellular localization of the GPI-associated proteins. Within the omega-minus region, amino acid residues at the omega-4 or -5 and omega-2 sites were important for the cell wall incorporation. Yap3p, a well characterized GPI-anchored plasma membrane aspartic protease, was localized in the cell wall when the omega-minus region was mutated to sequences containing Val or Ile at the omega-4 or -5 site and Val or Tyr at the omega-2 site.

Amino Acid Sequence↗
PubMed1998

A novel tumor suppressor locus on chromosome 18q involved in the development of human lung cancer.

The high incidence of loss of heterozygosity (LOH) on chromosome 18q in advanced non-small cell lung carcinomas indicates the presence of tumor suppressor gene(s) on this chromosome arm, which plays an important role in the acquisition of malignant phenotypes in lung cancers. In the present study, we examined 62 lung cancer specimens and 54 lung cancer cell lines for allelic imbalance at 11 microsatellite loci to define common regions of 18q deletions. Allelic imbalance of 18q was detected in 24 (55.8%) non-small cell lung carcinoma specimens and in 6 (31.6%) small cell lung carcinoma specimens, whereas a similar frequency of LOH was statistically inferred to occur in cell lines by analyzing marker homozygosity as an indirect measure of LOH. Five specimens and 11 cell lines showed partial or interstitial deletions of chromosome 18q, and 2 of them had homozygous deletions at the 18q21.1 region. A commonly deleted region was assigned between the D18S46 and y953G12R loci. The size of this region is less than 1 Mb, and the coding exons of three candidate tumor suppressor genes, Smad2, Smad4, and DCC, were mapped outside the region. This result suggests that the common region harbors a novel tumor suppressor gene involved in the progression of lung cancer.

Carcinoma, Non-Small-Cell Lung↗
PubMed1998

The significance of oligoclonal bands in multiple sclerosis in Japan: relevance of immunogenetic backgrounds.

We compared clinical and demographic features, MRI findings, and HLA profiles of 57 Japanese patients with multiple sclerosis (MS) between groups with and without oligoclonal IgG bands (OCB) in the cerebrospinal fluid (CSF). Patients with the optic-spinal form of MS (OpS-MS) or acute transverse myelopathy (ATM), which are distinctive and relatively common in Japanese MS, were excluded in this study. The OCB-positive rate was only 56.1% (32/57) among these 57 'conventional' MS patients, of whom clinical features were similar to those of Western MS patients. The demographic features, clinical course, disability, and cerebral abnormalities seen on MRI were similar in the OCB-negative and OCB-positive patient groups. HLA-DR2 antigen, which has been confirmed to be associated with MS in many populations, was more common in the OCB-positive than in the OCB-negative and control groups. Furthermore, DR4 antigen was statistically more common in the OCB-negative patient group. These results raise the possibility that the presence of OCB is related to the immunogenetic background of the patient, and that there may be at least two subpopulations in Japanese patients with 'conventional' MS from the viewpoint of immunogenetics. In one subpopulations, MS is associated with the DR2 antigen, and shows a stronger humoral immune response in the CSF, while in the other MS is associated with DR4, which has a milder humoral response. Further investigations involving more patients are warranted.

Adult↗
PubMed1998

Survival by Mac-1-mediated adherence and anoikis in phorbol ester-treated HL-60 cells.

During the exposure of human myelocytic leukemia HL-60 cells to phorbol diester, nonadherent cells die by apoptosis, but adherent cells survive and growth-arrest at G1 phase of the cell cycle. Here we have shown that the adherent cells rapidly died by apoptosis after forced detachment (anoikis), indicating that phorbol diester induced apoptosis by default. Dimethylsphingosine induced apoptosis in the adherent cells, and sphingosine-1-phosphate rescued the detached cells from apoptosis. Sphingosine kinase activity in adherent cells was higher than that in nonadherent cells and was decreased by forced detachment. It is likely that the phorbol diester-induced apoptosis and the adhesion-mediated survival are modulated by sphingosine and sphingosine-1-phosphate, respectively. The adherent cells were reverted and reproliferated when allowed to spontaneously detach from plastic surfaces by removal of phorbol diester. This result suggests that after removal of phorbol diester, the commitment signal of apoptosis by default is lost faster than the survival signal by adherence.

Apoptosis↗
PubMed1998

Involvement of Mac-1-mediated adherence and sphingosine 1-phosphate in survival of phorbol ester-treated U937 cells.

Phorbol esters exert a dual function in human leukemia cells, induction of differentiation and activation of integrin-mediated functions. Here we have shown that the plastic adherence of phorbol ester-treated U937 cells is mediated by expression of integrin Mac-1 (CD11b/CD18) on the cell surface and that these adherent cells exhibit anoikis (apoptosis when adherent cells are detached or adherence is inhibited). We used U937-derived clones overexpressing either antisense RNAs antisense to CD11b and CD18 mRNAs or mRNA from a truncated mutant CD11b gene. We have also shown that apoptosis in non-adherent cells or anoikis was mediated by sphingosine and that survival of adherent cells was achieved by a shift of the dynamic balance between sphingosine and sphingosine 1-phosphate toward the latter by adherence-activated sphingosine 1-kinase.

Apoptosis↗
PubMed1998

Enhanced expression of mitochondrial genes in senescent endothelial cells and fibroblasts.

It has been suggested that some mitochondrial genes are important in cellular senescence. In order to identify the mitochondrial genes that are involved in cellular senescence, we have constructed a cDNA library from senescent human vascular endothelial cells and isolated 86 senescence-specific cDNA clones by differential screening. Among the clones, we identified four distinct mitochondrial genes including NADH dehydrogenase subunit 2 (ND2), ND3, ATPase 6 and 16S ribosomal RNA. We then compared the levels of expression of these genes in young and senescent cells by using two endothelial and two fibroblast cell strains. Northern blot and slot blot hybridization confirmed that the expression levels of ND3, ATPase 6 and 16S rRNA were elevated in senescent cells of all four strains. The expression level of ND2 was also elevated during cellular senescence in three of the four strains. Because mitochondria are actively involved in oxidative phosphorylation and respiratory functions, the altered expression levels of these genes may participate in aging processes.

Adenosine Triphosphatases↗
PubMed1998

Stretch activates Jun N-terminal kinase/stress-activated protein kinase in vascular smooth muscle cells through mechanisms involving autocrine ATP stimulation of purinoceptors.

Mechanical strain has been implicated in phenotypic changes, including alteration of gene expression in vascular smooth muscle cells; however, the molecular basis for mechanotransduction leading to nuclear gene expression is largely unknown. We demonstrate in the present study that cyclic stretching of vascular smooth muscle cells dramatically activates Jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK) through an autocrine mechanism. Stretch causes time- and strength-dependent rise of the ATP concentration in media. The stretch-induced activation JNK/SAPK is attenuated by the addition of hexokinase or apyrase that scavenge ATP in media. Both the P2 receptor antagonist and the A1 subtype-selective P1 receptor antagonist partially inhibit stretch-induced activation of JNK/SAPK. The conditioned medium from stretched cells contains an activity to stimulate JNK/SAPK. The JNK-stimulating activity in the conditioned medium from stretched cells is attenuated by the addition of apyrase or P1 and P2 receptor antagonists. The addition of exogenous ATP or adenosine induces dose-dependent activation of JNK/SAPK. These results indicate that stretch activates JNK/SAPK in vascular smooth muscle cells through mechanisms involving autocrine stimulation of purinoceptors by ATP and its hydrolyzed product adenosine.

Adenosine Triphosphate↗
PubMed1998

Two types of chicken 2',5'-oligoadenylate synthetase mRNA derived from alleles at a single locus.

We have isolated two types of chicken 2',5'-oligoadenylate synthetase cDNAs, A and B, which encode predicted proteins of 508 amino acids (58316 Da) and 476 amino acids (54336 Da), respectively. The region of A-protein comprising 33 amino acid residues from 385Ala to 417Cys is substituted by a single amino acid 385Tyr in B-protein. The homology between chicken and mammalian 2',5'-oligoadenylate synthetases is 49.5% over the amino-terminal 337 residues. Proteins expressed from A- and B-cDNAs in E. coli cells were both active in synthesizing 2',5'-oligoadenylate. However, the activity of B-protein was 10-15% of that of A-protein. Southern blotting hybridization indicated that the chicken synthetases are encoded by a single gene. RT-PCR and PCR analyses of RNA and DNA of chicken erythrocytes together with the sequence data of the PCR products showed that A- and B-mRNAs are derived from alleles at a single locus encoding chicken 2',5'-oligoadenylate synthetase, designated as OAS * A and OAS * B. Chickens carrying OAS * A/B produce two types of synthetase with molecular masses of 58 and 54 kDa, and those carrying OAS * A/A produce only a single type of 58 kDa.

2',5'-Oligoadenylate Synthetase↗
PubMed1998

Association of CDKN2A(p16)/CDKN2B(p15) alterations and homozygous chromosome arm 9p deletions in human lung carcinoma.

To elucidate the possibility of the existence of multiple tumor suppressor genes on chromosome arm 9p, we performed genetic and epigenetic analyses of the CDKN2A/p16/MTS1 and CDKN2B/p15/MTS2 genes as well as homozygous deletion mapping of 9p in human lung carcinoma. To avoid overlooking genetic alterations due to contamination of noncancerous cells, we examined 32 non-small cell lung carcinoma (NSCLC) and 16 cell small cell lung carcinoma (SCLC) cell lines. (CDKN2A was mutated or homozygously deleted in 20 (63%) of 32 NSCLC cell lines, and methylation of the CpG island in the CDKN2A gene was detected in six of the 12 cell lines carrying the wild-type CDKN2A gene. Although homozygous deletions of the CDKN2B gene were also detected in NSCLC cell lines with CDKN2A deletions, mutation and methylation in the CDKN2B gene were infrequent. Thus, it was indicated that the CDKN2A gene rather than the CDKN2B gene plays a critical role as a tumor suppressor gene in NSCLC. Homozygous deletions on 9p were detected in 14 (44%) NSCLC cell lines. It is of note that two common regions of homozygous deletions were mapped proximal to the CDKN2A and CDKN2B loci, suggesting that tumor suppressor genes other than CDKN2A are present on 9p. In contrast to NSCLC, homozygous deletions on 9p as well as CDKN2A and CDKN2B alterations were infrequent in SCLC. Therefore, the pathogenetic significance of 9p alterations is likely to differ between SCLC and NSCLC.

Carcinoma, Small Cell↗