Biomedical subjects

Takanori Ueda

Publications and source records attributed to Takanori Ueda.

82 records · Page 5Linked to original sources

PubMed2002

1-beta-D-arabinofuranosylcytosine is cytotoxic in quiescent normal lymphocytes undergoing DNA excision repair.

We have sought to clarify the potential activity of the S-phase-specific antileukemic agent 1-beta-D-arabinofuranosylcytosine (ara-C), an inhibitor of DNA synthesis, in quiescent cells that are substantially non-sensitive to nucleoside analogues. It was hypothesized that the combination of ara-C with DNA damaging agents that initiate DNA repair will expand ara-C cytotoxicity to non-cycling cells. The repair kinetics, which included incision of damaged DNA, gap-filling by DNA synthesis and rejoining by ligation, were evaluated using the single cell gel electrophoresis (Comet) assay and the thymidine incorporation assay. When normal lymphocytes were treated with ultraviolet C or with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), the processes of DNA excision repair were promptly initiated and rapidly completed. When the cells were incubated with ara-C prior to irradiation or BCNU treatment, the steps of DNA synthesis and rejoining in the repair processes were both inhibited. The ara-C-mediated inhibition of the repair processes was concentration-dependent, with the effect peaking at 10 microM. The combination of ara-C with these DNA repair initiators exerted subsequent cytotoxicity, which was proportional to the extent of the repair inhibition in the presence of ara-C. In conclusion, ara-C was cytotoxic in quiescent cells undergoing DNA repair. This might be attributed to unrepaired DNA damage that remained in the cells, thereby inducing lethal cytotoxicity. Alternatively, ara-C might exert its own cytotoxicity by inhibiting DNA synthesis in the repair processes. Such a strategy may be effective against a dormant subpopulation in acute leukemia that survives chemotherapy.

Antimetabolites, Antineoplastic↗

PubMed2002

Inhibition of nucleotide excision repair by fludarabine in normal lymphocytes in vitro, measured by the alkaline single cell gel electrophoresis (Comet) assay.

Alkylating agents or platinum analogues initiate several excision repair mechanisms, which involve incision of the DNA strand, excision of the damaged nucleotide, gap filling by DNA resynthesis, and rejoining by ligation. The previous study described that nucleotide excision repair permitted incorporation of fludarabine nucleoside (F-ara-A) into the repair patch, thereby inhibiting the DNA resynthesis. In the present study, to clarify the repair kinetics in view of the inhibition by F-ara-A, normal lymphocytes were stimulated to undergo nucleotide excision repair by ultraviolet C (UV) irradiation in the presence or absence of F-ara-A. The repair kinetics were determined as DNA single strand breaks resulting from the incision and the rejoining using the alkaline single cell gel electrophoresis (comet) assay. DNA resynthesis was evaluated in terms of the uptake of tritiated thymidine into DNA. The lymphocytes initiated the incision step maximally at 1 h, and completed the rejoining process within 4 h after UV exposure. UV also initiated thymidine uptake, which increased time-dependently and reached a plateau at 4 h. A 2-h pre-incubation with F-ara-A inhibited the repair in a concentration-dependent manner, with the maximal inhibition by 5 mM. This inhibitory effect was demonstrated by the reduction of the thymidine uptake and by the inhibition of the rejoining. A DNA polymerase inhibitor, aphidicolin, and a ribonucleotide reductase inhibitor, hydroxyurea, were not so inhibitory to the repair process as F-ara-A at equimolar concentrations. The present findings suggest that inhibition of nucleotide excision repair may represent a novel therapeutic strategy against cancer, especially in the context of resistant cells with an increased repair capacity.

Antineoplastic Agents↗

PubMed2002

Dexamethasone-resistant human Pre-B leukemia 697 cell line evolving elevation of intracellular glutathione level: an additional resistance mechanism.

Glucocorticoids remain among the most important drugs in the treatment of acute lymphoblastic leukemia (ALL). Although the mechanisms of glucocorticoid resistance have been studied in some T-cell leukemic cell lines, less work has been done with B-cell lines. We established a dexamethasone (DEX)-resistant human pre-B lineage leukemia cell line (697/DEX) and investigated the mechanism of resistance. 697/DEX was over 430-fold more resistant to DEX compared with the parental cells (697/Neo). Overexpression of Bcl-2 protein was not observed in 697/DEX, different from the mechanism of resistance in Bcl-2-virus-infected cells (697/Bcl-2). Although the expression of p-glycoprotein (Pgp) in 697/DEX was positive, its functional activity was not detected. The numbers of glucocorticoid receptors (GR) in 697/DEX and 697/Bcl-2 were significantly lower than those in 697/Neo. In addition, 697/DEX and 697/Bcl-2 had higher levels of glutathione (GSH) than 697/Neo. In the presence of L-buthionine-(S, R)-sulfoximine (BSO), an inhibitor of GSH synthesis, both 697/DEX and 697/Bcl-2 recovered their sensitivity to DEX. Interestingly, cell death by the depletion of GSH did not involve caspase-3/7 activation in 697/Bcl-2 and 697/DEX, different from 697/Neo, suggesting a death mechanism through caspase-independent programmed cell death or necrosis. In conclusion, DEX-resistance in 697/DEX was related not only to a GR decrease, but also to an increase in intracellular GSH level in the DEX-resistant B-cell leukemia cell line. Circumvention of DEX-resistance with BSO may offer an approach to overcoming resistance to chemotherapy in B-cell lineage ALL.

Antimetabolites, Antineoplastic↗

PubMed2002

Prediction of sensitivity to STI571 among chronic myeloid leukemia patients by genome-wide cDNA microarray analysis.

One of the most critical issues to be solved in regard to cancer chemotherapy is the establishment of ways to predict the efficacy of anti-cancer drugs for individual patients. To develop a prediction system based on expression of specific genes, we analyzed expression profiles of mononuclear cells from 18 chronic myeloid leukemia (CML) patients who were treated with the tyrosine kinase inhibitor STI571. cDNA microarrays representing 23 040 genes identified 79 genes that were expressed differentially between responders and non-responders to STI571. On the basis of the expression patterns of 15 or 30 of these genes among the patients, we developed a "Prediction Score" system that could clearly separate the responder group from the non-responder group. Verification of this system using four additional ("test") cases succeeded in predicting the response of each of those four patients to the drug. These results provide the first evidence that gene-expression profiles can predict sensitivity of CML cells to STI571, and may eventually lead to the achievement of "personalized therapy" for this disease.

Adult↗

PubMed2002

Evaluation of arteriolar hyalinosis of the skin of patients with chronic congestive heart failure.

To investigate whether microvascular lesions are present in the skin of patients with chronic congestive heart failure (CHF), skin biopsies were performed at the time of cardiac catheterization, and the results were compared with control subjects. The diagnosis of CHF was done by cardiac catheterization with reference to the elevation of plasma levels of brain natriuretic peptide (BNP). Although the severity of arteriolar hyalinosis did not correlate with the New York Heart Association functional class, increased hyalinosis was found in skin biopsies from 17 of 20 patients with CHF, but in none of the 6 control subjects. These results indicate that microangiopathic alterations in arterioles may exist in patients with CHF and therapy for peripheral vascular remodeling might be considered for such patients.

Adult↗

PubMedDate not supplied

Neovascularization in pancreatic ductal adenocarcinoma: Microvessel count analysis, comparison with non-cancerous regions and other types of carcinomas.

Although neovascularization is regarded as an essential factor for tumor growth, it is unclear whether pancreatic adenocarcinoma is also influenced by this process. Furthermore, the reported microvessel count (MVC) data can not be compared due to the diversity of evaluating methods, and the relation between MVC data and metastatic potentials remains controversial. A total of 24 pancreatic adenocarcinomas and 24 adjacent non-cancerous pancreatic parenchyma were analyzed for MVC using anti-CD31 antibody. In addition, the MVC of 15 hypervascular tumors (10 hepatocellular carcinomas: HCC and 5 islet cell pancreatic tumors: ICT), 30 other types of adenocarcinomas (10 gastric, 10 colon and 10 intraductal papillary mucinous tumors of the pancreas: IPMT), as well as that of non-cancerous areas, were also analyzed. The extent of hepatic and peritoneal spread in 24 pancreatic adenocarcinoma patients was classified and correlations with MVC were evaluated. The mean MVC of 24 pancreatic adenocarcinomas (31.6 +/- 11.1) was actually lower than that of HCCs (91.6) or ICTs (56.4). The diversity is temperate as compared with that of other adenocarcinomas, i.e., 42.9 in gastric carcinomas, 35.6 in colon carcinomas and 32.5 in IPMT. MVC in non-cancerous areas were significantly higher in the pancreas (112.8) than in the stomach (29.6) or colon (26.3). MVC ratios of the cancerous area to the non-cancerous area were significantly lower in the pancreas (0.2818 +/- 0.100) than in the stomach (1.569 +/- 0.526, p<0.001) or the colon (1.423 +/- 0.493, p<0.001). MVC were higher in diffuse hepatic metastasis patients (36.0) than in limited metastasis patients (25.7). In conclusion, MVC in pancreatic adenocarcinoma revealed vascular volume to actually be lower than that of hypervascular tumors. We believe, however, that this hypovascularity is due mainly to contrast with the hyper-vascular non-cancerous pancreas, since MVC in the cancerous area itself was at the same level as in other adenocarcinomas. In addition, we revealed MVC to be of value for predicting the extent of liver metastasis.

Aged↗

PubMedDate not supplied

Expression of the antiapoptotic gene survivin in chronic myeloid leukemia.

Survivin, a unique member of the inhibitor of the apoptosis protein (IAPs) family, is over-expressed in many cancers but not in normal differentiated adult tissues. Using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR), we investigated patterns of survivin gene expression in a group of 12 patients with chronic myeloid leukemia (CML) representing both chronic and blastic phases of the disease. All 6 patients in chronic phase CML were uniformly negative for the survivin transcript, in contrast to 4 Philadelphia chromosome-positive (Ph+) CML patients in blastic crisis, all of whom (100%) were positive for survivin with tangible levels of expression. However, survivin expression was markedly down-regulated in 2 atypical CML patients with Philadelphia chromosome-negative (Ph-) blastic crisis. Our data indicates that up-regulation of survivin expression may be involved in typical CML evolution from the chronic into the blastic phase of the disease.

Apoptosis↗

PubMedDate not supplied

Virtual pancreatoscopy of pancreatic cancer.

BACKGROUND/AIMS: Virtual endoscopy is a new method of diagnosis using computer processing of three-dimensional images data sets. However, there are few reports about the clinical application of virtual endoscopy for the pancreas. In this study, we evaluated the feasibility of surface-rendered magnetic resonance virtual endoscopy for pancreatic cancer. METHODOLOGY: Twenty-six cases of pancreatic cancer were studied. Fifteen patients had pancreatic head cancer, 7 had pancreatic body cancer, and 4 had pancreatic tail cancer. Twelve patients underwent surgical resection of the pancreas. Magnetic resonance imaging data were acquired with a 1.5-T clinical imager (Signal.5; GE Medical Systems, USA). We used a multislab single-shot fast spin-echo sequence. Section thickness was between 2 and 3 mm in the coronal plane. Three-dimensional reconstructed images and virtual endoscopic images were generated with Advantage Windows by GE. RESULTS: Virtual endoscopic images could be generated in 20 patients with pancreatic cancer (76.9%). In these cases, we were able to observe the inner surface of the pancreatic duct and the stricture from not only the pancreatic head but also the pancreatic tail. Clear virtual images could not be generated in 6 cases. We were able to divide the 20 cases in which images could be generated into groups according to the appearance of the stricture. The edge of the stricture appeared to be protruding in 4 cases (15.4%), and appeared to be polygonal in 13 cases (50.0%). In 3 cases, we recognized the existence of a stricture, but the detail of the stricture was unclear. CONCLUSIONS: Virtual endoscopy caused minimal discomfort compared to real endoscopic examination, and it can access cystic lesions and the pancreatic duct behind the stricture. It is concluded that virtual endoscopy for pancreatic cancer has potential clinical utility.

Aged↗

PubMedDate not supplied

Pharmacological study of modified intermediate-dose cytarabine therapy in patients with acute myeloid leukemia.

BACKGROUND: Instead of the original intermediate dose (0.5 g/m2), a modified intermediate-dose 1-beta-D-arabinofuranosylcytosine (ara-C) therapy (1 g/m2, 1-h intravenous infusion) was pharmacologically studied in 11 leukemic patients. PATIENTS AND METHODS: The concentrations of ara-C and its inactive metabolite, 1-beta-D-arabinofuranosyluracil (ara-U) in the plasma, urine and cerebrospinal fluid were determined using high performance liquid chromatography. RESULTS: The plasma ara-C reached a peak (61.2 +/- 52.7 microM) that far surpassed the saturating level for intracellular activation of the drug. The plasma ara-U reached its peak (139.8 +/- 40.0 microM) and was maintained with a half-life of 277 +/- 76 min. About 60% of the administered drug was recovered, mainly as ara-U in urine within 12 h. In contrast to the original intermediate dose, the therapeutic ara-C levels (above 0.4 microM) persisted in the central nervous system. The therapy salvaged one relapsed leukemia patient with central nervous system involvement. CONCLUSION: Modified intermediate-dose ara-C provides a sufficient plasma ara-C level with a concomitant therapeutic concentration in the cerebrospinal fluid.

Acute Disease↗

PubMedDate not supplied

Arsenic trioxide circumvents multidrug resistance based on different mechanisms in human leukemia cell lines.

To determine the antitumor effect of arsenic trioxide (As2O3) on multidrug-resistant cells, we applied 3 human leukemia cell lines: daunorubicin (DNR)-resistant cell line K562/D1-9, which overexpresses p-glycoprotein (Pgp); DNR and 1-beta-D-arabinofuranosylcytosine (Ara-C) double-resistant cell line HL60/AD, which overexpresses multidrug resistance-associated protein (MRP1); and Bcl-2-transfected pre-B lineage leukemia cell line 697/Bcl-2. Interestingly, K562/D1-9 showed collateral sensitivity. Only HL60/AD showed small cross resistance, but 697/Bcl-2 had no resistance to As2O3. An intracellular content of glutathione (GSH) played a critical role in sensitivity to As2O3. Buthionine-sulfoximine (BSO), which reduces the GSH content, not only increased the As2O3 sensitivity but also conquered the MRP1-related cross resistance in HL60/AD. In conclusion, As2O3 was effective in all 3 cell lines, suggesting that As2O3 may be a promising agent for the treatment of multidrug-resistant leukemia.

ATP Binding Cassette Transporter, Subfamily B, Mem↗