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Biomedical subjects

Kenji Takai

Publications and source records attributed to Kenji Takai.

12 recordsLinked to original sources
PubMed2006

The utility of 18F-fluorodeoxyglucose positron emission tomography for early diagnosis of radiation-induced myocardial damage.

PURPOSE: We evaluated the clinical significance of focal increased uptake in the basal myocardium on F-fluorodeoxyglucose positron emission tomography (FDG-PET) in patients with esophageal cancer after radiotherapy. METHODS AND MATERIALS: Between August 2004 and July 2005, a total of 64 patients who had been irradiated for thoracic esophageal cancer underwent FDG-PET at least three months after the completion of chemoradiotherapy. Some patients showed increased FDG uptake in the basal portion of the myocardium. To clarify the clinical significance of these findings, further examinations of hearts were performed. The dose distribution in the myocardium with high FDG uptake was also analyzed retrospectively. RESULTS: Thirteen (20.3%) of the 64 patients showed high FDG uptake in the basal myocardium corresponding to the irradiated fields compared with FDG uptake in the myocardium outside the irradiated fields. Eight of the 13 patients consented to undergo examinations of the heart. Five of those eight patients showed low 123I-BMIPP uptake and four showed low 201TlCl uptake in the myocardium corresponding with high FDG uptake regions. In two patients, delayed enhancement was found in some parts of the area with high FDG uptake on Gd-DTPA magnetic resonance imaging (MRI), and the delay-enhanced lesion showed hypokinesia on cine-MRI in one patient. CONCLUSIONS: FDG-PET often shows focal increased uptake in the basal myocardium after radiotherapy for esophageal cancer. This finding indicates the possibility of radiation-induced cardiac damage, and cardiac function and symptoms of such patients should be followed carefully.

Aged↗
PubMed2006

Classification of human liver transplant recipients by their preoperative CD8+ T cell subpopulation and its relation to outcome.

The primed status of T cells is markedly different among liver transplant recipients, due to a lifetime of antigen exposure and reduced thymopoiesis by aging, and diseases. This study aims to characterize the preoperative immunological status of CD8+ T cell subpopulations and relate it to the outcome for liver transplant recipients. We classified 112 liver transplant recipients into 5 groups, based on hierarchical clustering of the CD8+CD45 isoform proportion of T cells. In Groups I and II (pediatric), the naive T cell proportion was more than 50%. In adult recipients, Group III was characterized by a naive T cell proportion of 50%, Group IV had the greatest effector/memory T cells (EM), and Group V had the greatest proportion of effector T cells. In Groups IV and V, the effector T cell proportion was considerably higher, and was accompanied by marked downregulation of the CD27+CD28+ subsets and upregulation of interferon gamma (IFN)-gamma, tumor necrosis factor-alpha, and perforin expression. Group V recipients tended to be complicated postoperatively, with a significantly reduced survival rate (1 yr, 66.8%) and markedly reduced Eastern Cooperative Oncology Group performance status.

Adolescent↗
PubMed2005

Salvage radiation therapy for residual superficial esophageal cancer after endoscopic mucosal resection.

PURPOSE: To analyze the outcomes of radiation therapy for patients with residual superficial esophageal cancer (rSEC) after endoscopic mucosal resection (EMR). METHODS AND MATERIALS: From May 1996 to October 2002, a total of 30 rSEC patients without lymph node metastasis received radiation therapy at Tohoku University Hospital and associated hospitals. The time interval from EMR to start of radiation therapy ranged from 9 to 73 days (median interval, 40 days). Radiation doses ranged from 60 Gy to 70 Gy (mean dose, 66 Gy). Chemotherapy was used in 9 of 30 patients (30%). RESULTS: The 2-year, 3-year, and 5-year overall survival rates and cause-specific survival rates were 91%, 82%, and 51%, respectively, and 95%, 85%, and 73%, respectively. The 2-year, 3-year, and 5-year local control rates for mucosal cancer were 91%, 91%, and 91%, respectively, and those for submucosal cancer were 89%, 89%, and 47%, respectively. These differences in survival rates for patients with two types of cancer were not statistically significant. Local recurrence and lymph node recurrence were more frequent in patients with submucosal cancer than in patients with mucosal cancer (p = 0.38 and p = 0.08, respectively). Esophageal stenosis that required balloon dilatation developed in 3 of the 30 patients, and radiation pneumonitis that required steroid therapy developed in 1 patient. CONCLUSIONS: Radiation therapy is useful for preventing local recurrence after incomplete EMR.

Aged↗
PubMed2005

Decrease of reactive-oxygen-producing granulocytes and release of IL-10 into the peripheral blood following leukocytapheresis in patients with active ulcerative colitis.

AIM: To investigate the clinical efficacy of leukocytapheresis (LCAP) in patients with active ulcerative colitis (UC), and to elucidate the mechanisms by determining the changes in the cytokine levels in the peripheral blood and of the functions of the peripheral blood leukocytes in these patients. METHODS: The subjects were 19 patients with active UC, with a mean clinical activity index (CAI) of 9.2. The LCAP was conducted using Cellsorba E. In each session of LCAP, 2-3 L of blood at the flow rate of 30-50 mL/min was processed. The treatment was carried out in approximately 1-h sessions, once a week, for 5-10 wk. Blood samples for determination of the cytokine levels were collected from the inflow side of the column (site of dehematization; at the start of LCAP) and outflow side of the column (at the end of LCAP). Blood samples for the determination of reactive-oxygen-producing cells were collected from the peripheral blood before and after LCAP. RESULTS: LCAP resulted in clinical improvement in all the 19 patients of UC recruited for this study. Remission (CAI: < or = 4) was noted in 15 (79%) of the 19 patients. The blood level of the pro-inflammatory cytokine IL-6 was found to be decreased following treatment by LCAP, and the level of the anti-inflammatory cytokine IL-10 at the outflow side of the LCAP column was found to be significantly elevated as compared to that at the inflow side of the column. The reactive-oxygen-producing granulocytes in the peripheral blood of UC patients was increased as compared to that in healthy persons and the increase was found to be decreased following treatment by LCAP. CONCLUSION: LCAP exerted a high therapeutic efficacy in patients with active UC. Our findings suggest that LCAP is associated with enhanced production of the inhibitory cytokine IL-10 to indirectly inhibit the functions of the inflammatory leukocytes, and that inflammation is also considerably attenuated by the direct removal of reactive-oxygen-producing neutrophils from the peripheral blood.

Adult↗
PubMed2005

Role of bcl-2 mRNA in homeostatic proliferation in circulating T-cells in human liver transplant patients after T-cell depletion.

BACKGROUND: Prolonged T-cell depletion after liver transplantation leads to life-threatening infections. Members of the anti-apoptotic Bcl-2 gene family can maintain T-cell viability. T-cell numbers and their Bcl-2 expression following living donor liver transplantation (LDLT) were analyzed in 108 surviving and 13 deceased recipients. MATERIALS AND METHODS: Bcl-2 mRNA levels and phenotypic changes of T-cells were examined by quantitative PCR and by measuring expression of CD45RO and CCR7. RESULTS: Based on the restoration of peripheral T-cell numbers, the 108 surviving recipients were classified into three groups. All recipients showed T-cell depletion, down to approximately 30% of pretransplant levels within 3 h of graft reperfusion. In Group I, the T-cell numbers were rapidly restored to pretransplant levels, within 5 days, with a rapid decrease in Bcl-2 mRNA levels immediately after LDLT. In Group II, the T-cell numbers were restored to normal levels by 19 days, with down-regulation of Bcl-2 mRNA. In Group III, the T-cell numbers were maintained at low levels for much longer, with high levels of Bcl-2 mRNA. In all three groups of recipients, there was statistically significant (r = -0.78) inverse correlation between T-cell numbers and Bcl-2 mRNA. CONCLUSIONS: For successful transplantation, homeostatic restoration of T-cells must occur as soon as possible. Evaluation of peripheral T-cell numbers and of Bcl-2 expression may have therapeutic potential in identifying those transplant patients who face increased risk of infection.

Adolescent↗
PubMed2005

Expression of hTERT mRNA in a mortal liver cell line during S phase without detectable telomerase activity.

Normal human liver cells have a limited capacity for proliferation due to telomere shortening, whereas immortalized cells prevent shortening of the 3' single strand telomeric repeat by expressing telomerases, including human telomerase reverse transcriptase (hTERT). The hTERT transcript contains three deletion sites that give rise to alternatively spliced variants (ASVs). Recently, hTERT expression was observed in cycling primary presenescent human fibroblasts, which were believed to lack hTERT expression and telomerase activity. hTERT mRNA was expressed in the synthesis (S) phase of the cell cycle. Although hTERT mRNA has eight isoforms, it is not known which of the hTERT ASVs are expressed in S phase. In order to determine the possible relationships between the cell cycle and ASV expressions, we measured the full-length isoform and ASVs of hTERT mRNA in a mortal liver cell line and immortal cell lines that were synchronized in S phase of the cell cycle. Using RT nested-PCR analysis, the full-length isoform and alpha-deletion ASV of hTERT were detected in the LI90 mortal liver cell line at points when cells in S phase represented >48% of the cell population without detectable telomerase activity. hTERT was always expressed in the HLE and Huh-7 hepatocellular carcinoma cell lines, regardless of the cell cycle. Our results suggest the possibility that telomerase is regulated in a cell cycle-dependent manner in normal liver cells.

Alternative Splicing↗
PubMed2005

[Flow cytometric analysis of mesothelial cells in peritoneal dialysis effluent].

According to recent reports, deformity and size of mesothelial cells reflect mesothelial condition. We applied flow cytometry (FCM) to the analyzation of mesothelial cells in peritoneal dialysis effluent (PDE) and the relationship between the period of peritoneal dialysis (PD) and peritoneal function. Eighteen patients treated for two to 89 months by PD were selected. Their dialysate: plasma creatinine ratio (D/P creatinine)was 0.67 +/- 0.086 (0.53 to 0.87). Overnight PDE was drained and centrifuged. The cell population of peritoneal cells identified by anti-cytokeratin, CD14 and 45 antibodies was studied by FCM. Cytokeratin positive cells were identified as mesothelial cells, distinct from macrophages, granulocytes or lymphocytes. The forward scatter (FSC) of cytokeratin positive cells, fluorescence intensity of cytokeratin and percentage of cytokeratin-positive cells in PDE were 395.6 +/- 55.5 (298.31 to 527.72), 333.9 +/- 272.9 (67.55 to 1,071.95), and 6.75 +/- 6.1% (0.44 to 21.14), respectively. There was a positive correlation between D/P creatinine and FSC, and a negative correlation between D/P creatinine and cytokeratin fluorescence intensity or the percentage of cytokeratin positive cells. However, there was no correlation between the period of PD and FSC, cytokeratin fluorescence intensity or the percentage of cytokeratin-positive cells. It was suggested that the alteration of mesothelial cells is not necessarily influenced by the period of PD, but influences peritoneal function. It was found that the analysis of cell population by FCM reflects the morphological and functional changes in the peritoneum of patients on PD.

Adult↗
PubMed2004

Hepatocyte growth factor plays roles in the induction and autocrine maintenance of bone marrow stromal cell IL-11, SDF-1 alpha, and stem cell factor.

OBJECTIVE: Bone marrow (BM) stroma provides the microenvironment required for long-term hematopoiesis, and this is supported by direct interaction between stromal cells and hematopoietic cells, mediated by adhesion molecules, and through cytokine releases from the BM stroma. In a previous study, we demonstrated that hepatocyte growth factor (HGF) is one of the cytokines constitutively produced from BM stromal cells, promoting hematopoiesis mainly in an indirect way. We also showed that stromal cells themselves express HGF receptor c-MET. It was therefore postulated that HGF exerts its effect on hematopoiesis and maintenance of the hematopoietic microenvironment in a paracrine and autocrine manner. METHODS: The effect of HGF on stromal cells was analyzed by neutralizing intrinsic HGF. RESULTS: Addition of neutralizing anti-HGF antibody inhibited the ability of BM stromal cells to support colony formation from CD34(+) cells and reduced production of significant cytokines from stromal cells, interleukin-11 (IL-11), stromal cell-derived factor-1 alpha (SDF-1 alpha), and to a lesser extent, stem cell factor (SCF). Furthermore, this neutralizing antibody reduced proliferation of stromal cells and inhibited adhesion of stromal cells to collagen type IV and fibronectin. Inhibition of adhesion to fibronectin was mediated by inhibition of alpha(5)beta(1)-integrin. CONCLUSION: These findings indicate that HGF constitutively produced from BM stromal cells is an autocrine regulator, which is able to maintain the hematopoietic microenvironment through stimulating proliferation and adhesion to the extracellular matrix and promoting hematopoiesis through inducing constitutive production of IL-11, SDF-1 alpha, and SCF by stromal cells themselves.

Autocrine Communication↗
PubMed2003

Helicobacter pylori cytotoxin: a novel ligand for receptor-like protein tyrosine phosphatase beta (review).

The impacts of toxins are generally observed as acute intoxications, whereas the environmental health effects of chronic exposure to mostly low levels of toxins are only poorly documented and are an emerging issue. Furthermore, toxins are potentially useful as tools to study the physiological role of particular channels or to determine structural features of channels that are important for their function. Recent studies suggest that vacuolating cytotoxin (VacA) is a novel ligand for receptor protein tyrosine phosphatase (RPTP) beta. VacA is a virulence factor of Helicobacter pylori that is involved in gastric ulceration and cancer in experimental animals and humans. VacA may represent the chronic exposure of A-B family of bacterial endotoxins and be a useful probe for RPTPbeta functions in the gastrointestinal system.

Bacterial Proteins↗
PubMed2002

Role of L-selectin in the development of ventilator-associated pneumonia in patients after major surgery.

BACKGROUND: The circulating level of soluble L-selectin (sL-selectin) has been reported to be low in adult respiratory distress syndrome and acute lung injury. This study explores the role of L-selectin in the development of ventilator-associated pneumonia (VAP) in patients undergoing major surgery. PATIENTS AND METHODS: Thirty-four patients who underwent esophagectomy were maintained by mechanical ventilation in a surgical intensive care unit. Fourteen patients developed VAP by postoperative day (POD) 7, while 20 patients did not. The plasma levels of soluble adhesion molecules and elastase were measured serially by ELISA or EIA. The expression of L-selectin on polymorphonuclear neutrophils (PMNs) was analyzed by flow cytometry. RESULTS: In multiple logistic regression analysis, only the preoperative plasma level of sL-selectin was significantly associated with VAP. The plasma sL-selectin level before surgery was significantly lower in the patients who developed VAP compared with the patients who did not develop VAP. After surgery, the level of sL-selectin did not change. The plasma level of soluble intercellular adhesion molecule-1 increased in the patients with and without VAP. The plasma level of soluble vascular cell adhesion molecule-1 was significantly higher in the patients with VAP. L-selectin expression on PMNs showed a peak on POD 2 in the patients without VAP, whereas it was impaired in the patients with VAP. CONCLUSIONS: Determination of the preoperative plasma level of sL-selectin may help to identify patients at high risk for VAP after esophagectomy.

Cell Adhesion Molecules↗
PubMed2002

Establishment of a monosomy 7 leukemia cell line, MONO-7, with a ras gene mutation.

A monosomy 7 leukemia cell line, designated MONO-7, was established from the peripheral blood of a patient with monosomy 7 acute myelocytic leukemia (French-American-British classification M0). The cells were cultured continuously for more than 24 months in RPMI-1640 medium supplemented with 10% heat-inactivated fetal calf serum. The cell line exhibits an unclassified appearance. Cytochemically, alpha-naphthol-acetate esterase and myeloperoxidase are negative. Immunophenotypically, the cell line expresses CD33, CD13, CD56, CD34, CD38, HLA-DR, and CD45, but lacks T and B cell-associated antigens. Karyotypic analysis of the cell line showed only 45,XY,-7. Analysis of the N-ras gene mutation demonstrated identical mutations in fresh leukemic cells and the MONO-7 cell line. Clonal rearrangements of the immunoglobulin heavy-chain gene, T-cell receptor beta-chain gene, or T-cell receptor gamma-chain gene were not found in DNA extracted from MONO-7 cells. The growth of MONO-7 cells in vitro was stimulated by recombinant human granulocyte-macrophage colony-stimulating factor or interleukin 3. To our knowledge, this is the first report of the establishment of a cell line with the karyotype 45,XY,-7 without any other abnormality and with a ras gene mutation.

Acute Disease↗