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Yuichi Nakamura

Publications and source records attributed to Yuichi Nakamura.

16 recordsLinked to original sources
PubMed2003

Leukemia-related transcription factor TEL accelerates differentiation of Friend erythroleukemia cells.

TEL belongs to a member of the ETS family transcription factors that represses transcription of target genes such as FLI-1. Although TEL is essential for establishing hematopoiesis in neonatal bone marrow, its role in erythroid lineage is not understood. To investigate a role for TEL in erythroid differentiation, we introduced TEL into mouse erythroleukemia (MEL) cells. Overexpressing wild-type-TEL in MEL cells enhanced differentiation induced by hexamethylene bisacetamide or dimethylsulfoxide, as judged by the increased levels of erythroid-specific delta-aminolevulinate synthase and beta-globin mRNAs. TEL bound to a corepressor mSin3A through the helix-loop-helix domain. A TEL mutant lacking this domain still bound to the ETS binding site, but lost its transrepressional effect. This mutant completely blocked erythroid differentiation in MEL cells. Moreover, it showed dominant-negative effects over TEL-mediated transcriptional repression and acceleration of erythroid differentiation. Endogenous TEL mRNA was found to increase during the first 3 days in differentiating MEL cells and drastically decrease thereafter. All these data suggest that TEL might play some role in erythroid cell differentiation.

5-Aminolevulinate Synthetase↗
PubMed2003

Monocytic leukemia with CALM/AF10 rearrangement showing mediastinal emphysema.

The t(10;11)(p12-14;q14-21) is a non-random translocation that results in the fusion of CALM gene on chromosome 11 with AF10 gene on chromosome 10. This translocation is observed in acute myeloid leukemia, acute lymphoblastic leukemia, and lymphoblastic lymphoma. Here we report a patient with t(10;11) who was diagnosed with AML-M4. Reverse transcriptase-polymerase chain reaction (RT-PCR) assay revealed one type of CALM/AF10 and three types of AF10/CALM fusion transcripts. Sequencing analysis for these RT-PCR products determined the breakpoint in CALM at nucleotide (nt) 1926-1927 and in AF10 at nt 423-424. The latter breakpoint was the same as that identified in three monocytic cell lines carrying t(10;11). After achieving complete remission, the patient developed mediastinal emphysema during the course of consolidation therapy, possibly due to the necrosis of his mediastinal mass. Monocytic leukemias with CALM/AF10 fusion are frequently associated with mediastinal invasion. We need to pay special attention to such a complication, even if the chest X-ray is normal at presentation.

Adolescent↗
PubMed2003

Does enhanced expression of the Na+-Ca2+ exchanger increase myocardial vulnerability to ischemia/reperfusion injury in rabbit hearts?

Reverse-mode activation of the Na+-Ca2+ exchanger (NCX) at the time of reperfusion following ischemia contributes to Ca2+ overload and cardiomyocyte injury. The aim of the present study was to determine whether increased NCX in the myocardium that survived after infarction enhances its vulnerability to ischemia/reperfusion injury. Rabbits were divided into post-MI and sham groups and underwent ligation of the left circumflex coronary artery and sham operation, respectively. Two weeks later, hearts were isolated and perfused with crystalloid in the Langendorff mode with monitoring of left ventricular (LV) pressure. NCX level in the myocardium was determined by Western blotting. Myocardial stunning was induced by 5 episodes of 5-min global ischemia/5-min reperfusion. Using separate groups of hearts, myocardial infarction was induced by 30-min global ischemia/2-h reperfusion with or without treatment with 0.3 microM KB-R7943, a reverse-mode selective blocker of NCX. Heart weight-to-body weight ratio was 20% larger and NCX protein level was 60% higher in the post-MI group than in the sham group. However, there were no significant differences between severities of myocardial stunning after the repetitive ischemia/ reperfusion (18 +/- 7 vs. 25 +/- 2% reduction in LV developed pressure) and between infarct sizes after 30-min ischemia (59.1 +/- 4.1 vs. 63.0 +/- 4.5% of risk area) in the post-MI and sham groups. KB-R7943 limited infarct size in the post-MI group by 53%, and the extent of this protection was not different from that we have reported for hearts without previous infarcts (i.e. 45% reduction of infarct size). These results suggest that enhanced NCX expression does not necessarily increase myocardial vulnerability to myocardial stunning and infarction.

Animals↗
PubMed2003

LCAT-dependent conversion of prebeta1-HDL into alpha-migrating HDL is severely delayed in hemodialysis patients.

Prebeta1-HDL is a minor HDL subfraction that acts as an efficient initial acceptor of cell-derived free cholesterol. During 37 degrees C incubation, plasma prebeta1-HDL decreases over time due to its conversion to alpha-migrating HDL by lecithin:cholesterol acyltransferase (LCAT). This conversion may be delayed in hemodialysis patients who have decreased LCAT activity. To clarify whether LCAT-dependent conversion of prebeta1-HDL to alpha-migrating HDL is delayed in hemodialysis patients, prebeta1-HDL concentrations were determined in 45 hemodialysis patients and 45 gender-matched control subjects before and after 37 degrees C incubation with and without the LCAT inhibitor. It was found that the baseline prebeta1-HDL concentration in hemodialysis patients was more than twice that in the controls (44.9 +/- 21.4 versus 19.8 +/- 6.7 mg/L apoAI; P < 0.001). After 2-h incubation, the LCAT-dependent decrease in prebeta1-HDL in hemodialysis patients was about one-third of that in the controls (30 +/- 27 versus 97 +/- 17% of baseline; P < 0.01). The LCAT-dependent rate of decrease in prebeta1-HDL levels (DR(prebeta1)) was the same for samples from hemodialysis patients exhibiting normal (> or =1.03 mmol/L) and low HDL-cholesterol levels (32 +/- 32 versus 28 +/- 23% of baseline; NS). DR(prebeta1) was positively correlated with LCAT activity (r = 0.617; P < 0.001). In conclusion, the LCAT-dependent conversion of prebeta1-HDL to alpha-migrating HDL is severely delayed in hemodialysis patients. The impaired catabolism of prebeta1-HDL may accelerate atherosclerosis in hemodialysis patients.

Adult↗
PubMed2003

Significance of asymmetric dimethylarginine (ADMA) concentrations during coronary circulation in patients with vasospastic angina.

The basal activity of nitric oxide (NO) is reduced in spastic arteries of patients with vasospastic angina (VSA). Elevated concentrations of ADMA are associated with reduced NO production and impaired endothelium-dependent vasodilatation. The aim of this study was to elucidate the role of ADMA and its relationship to NO end-products (NOx; nitrate + nitrite) during coronary circulation in patients with VSA. The plasma ADMA and NOx concentrations during coronary circulation were evaluated in 16 VSA and 16 control patients. Blood samples were obtained from the coronary sinus (V) and the ostium of the left coronary artery (A), and the (V-A) differences of ADMA and NOx were determined. The coronary sinus plasma ADMA concentration in patients with VSA was higher than that in the control. The coronary sinus - arterial (V-A) difference of NOx was negative in the VSA group and approximately zero in the control group (VSA group =-1.4 micromol/L, control group =-0.1 micromol/L, p=0.0005). Furthermore, in the VSA patients, there was a negative correlation between the (V-A) difference of NOx and the basal coronary artery tone at the site of spasm (r=-0.60, p=0.015). A significant negative correlation between the (V-A) differences of NOx and ADMA was observed in patients with VSA (r=-0.52, p<0.05), but not in those of the control. Higher ADMA concentrations might cause the reduced formation of NO that underlies the pathophysiology of coronary vasospasm.

Aged↗
PubMed2003

Therapeutic role of pericardiocentesis for acute necrotizing eosinophilic myocarditis with cardiac tamponade.

We describe a patient with acute necrotizing eosinophilic myocarditis who recovered rapidly after pericardial drainage and without corticosteroid therapy. The 25-year- old man was referred to our hospital with suspected acute myocardial infarction on the basis of severe epigastralgia, abnormal Q waves and ST elevation on electrocardiography, and an increase in cardiac enzymes. Echocardiography disclosed pericardial effusion that compressed the right ventricle, left ventricular dysfunction in conjunction with posterolateral hypokinesis, and a thickened ventricular wall but no mural thrombus. The eosinophil count in the peripheral blood was slightly increased. Coronary angiography showed normal arteries and thus prompted an endomyocardial biopsy. The patient was transferred to the intensive care unit with a clinical diagnosis of myocarditis associated with cardiac tamponade. Emergency pericardiocentesis relieved symptoms immediately. The cells in the pericardial effusion were mainly eosinophils; interleukin 5 and interleukin 13 levels were predominantly elevated, and the effusion was drained for 5 days. The biopsy specimen revealed necrotizing eosinophilic myocarditis. Left ventricular function recovered within a week without corticosteroid therapy. No relapse was observed as of 8 months after diagnosis.

Adult↗
PubMed2002

Functional regulation of TEL by p38-induced phosphorylation.

TEL is a nuclear phosphoprotein that belongs to a member of the ETS family transcription factors. TEL acts as a tumor suppressor and is essential for establishing hematopoiesis in neonatal bone marrow. Because TEL possesses multiple putative mitogen-activated protein (MAP) kinase phosphorylation sites, we here investigated functional regulation of TEL via stress signaling pathways. We showed that TEL becomes phosphorylated in vivo by activated p38 but not by JNK1. The constitutive and inducible phosphorylation sites were found to be Ser(22) and Ser(257), respectively. TEL bound to p38 and was directly phosphorylated in vitro by p38. In vivo p38-dependent phosphorylation reduced trans-repressional abilities of TEL through ETS-binding consensus site. These data indicate that TEL's functions are potentially regulated by p38 which is activated by various kinds of stresses. TEL could be a constituent downstream of the specific MAP kinase in the signal transduction system.

Animals↗
PubMed2002

SREBP-2 and NF-Y are involved in the transcriptional regulation of squalene epoxidase.

The expression of squalene epoxidase (SE) is highly regulated transcriptionally by cholesterol. To elucidate these molecular mechanisms, we isolated the human and rat genomic clones. The entire human SE gene was about 24 kb long and organized into 11 exons with 10 introns. Unidirectional deletion analysis of the human 5(')-flanking region indicated that the sequence between -264 and -230 bp conferred cholesterol sensitivity on a reporter gene. This region contained a potential copy of consensus sterol regulatory element (SRE) sequence (CCACGCAAC) previously identified in the promoter of cholesterogenic and its related genes. The transcriptional activation observed under overexpression of sterol regulatory element binding protein-2 (SREBP-2) supported the functional role of the SRE sequence. Another deletion analysis showed that the sequence -207 to -192 bp was also active and it contained nuclear factor Y (NF-Y) binding site. Both sites might play critical roles in sterol mediated regulation of SE gene.

5' Flanking Region↗
PubMed2002

Expression of the TEL/EVI1 fusion transcript in a patient with chronic myelogenous leukemia with t(3;12)(q26;p13).

The t(3;12)(q26;p13) translocation is a recurrent chromosomal aberration observed in myeloid malignancies. It has been shown that the translocation results in the fusion of the TEL (ETV6) gene at 12p13 and the EV11 gene at 3q26. We report the first case with Philadelphia (Ph)-positive chronic myelogenous leukemia (CML) expressing the TEL/EVI1 fusion transcript. A 26-year-old man was initially diagnosed as having the chronic phase of Ph-positive CML. The t(3;12)(q26;p13) emerged 16 months prior to the myeloid blastic crisis. Reverse transcriptase-polymerase chain reaction detected the TEL/EVI1 transcript without the intervening 5' non-coding exon of EVI1, suggesting that inappropriate expression of the EVI1 protein driven by the TEL promotor could play a critical role in progression to the blast crisis of CML.

Adult↗
PubMed2002

N-ras and p53 gene mutations in Japanese patients with myeloproliferative disorders.

Alterations of the N-ras oncogene and p53 tumor suppressor gene have been demonstrated to play an important role in pathogenesis of hematological malignancies. We simultaneously investigated genetic lesions of both genes in bone marrow cells from 64 Japanese patients with myeloproliferative disorders (MPD), including polycythemia vera (PV), essential thrombocythemia (ET), and idiopathic myelofibrosis (MF), by direct sequencing analysis. No mutations of the N-ras gene were detected in any cases. Two patients, one with chronic neutrophilic leukemia derived from PV and one with acute mylogenous leukemia derived from ET, exhibited three mutations of the p53 gene. Among them, two were missense mutations in exon 5 or 7 and one was a deletion in exon 5. All samples in chronic phase or from MF were devoid of mutations in both genes. These data suggested that disruptions of both genes are extremely rare in MPD in chronic phase and that loss of functions in the p53 gene could be involved in progression of MPD such as PV and ET.

Adult↗
PubMed2002

Diagnostic significance of serum soluble transferrin receptors in various anemic diseases: the first multi-institutional joint study in Japan.

Serum soluble transferrin receptor (sTfR) has been reported to be higher in patients with iron deficiency or with elevated erythropoiesis. In the present study, serum sTfR was measured in various anemic diseases and their clinical significance was examined in a multi-institutional joint study. Serum sTfRs in patients with the following anemic diseases were markedly higher than those in normal healthy adults: non-treated iron deficiency anemia (IDA) (9.13 +/- 7.04 mg/l, n = 52, p < 0.0001), anemia of chronic disorders (ACD) (3.45 +/- 1.38 mg/l, n = 20, p < 0.0001), hemolytic anemia (HA) (5.57 +/- 3.26 mg/l, n = 17, p < 0.0001), and myelodysplastic syndrome (MDS) (4.03 +/- 2.83 mg/l, n = 20, p < 0.0001). There were significant differences between IDA and ACD (p < 0.0001), between aplastic anemia (AA) (1.58 +/- 1.26 mg/l, n = 16) and MDS (p < 0.001), and between AA and MDS with refractory anemia (MDS-RA) (4.16 +/- 3.40 mg/l, n = 9) (p < 0.02). In patients with chronic renal failure (CRF), serum sTfR levels and serum sTfR/log serum ferritin ratios (sTfR/F index) were compared in the two classified groups according to Muirhead's criteria, as IDA and non-IDA groups with or without recombinant human erythropoietin (rHuEPO) treatment. Significantly high levels of both serum sTfR (p < 0.0001) and the sTfR/F index (p < 0.0001) were observed in IDA without rHuEPO treatment. Especially in CRF with rHuEPO treatment, the sTfR/F index showed marked elevation in the IDA group (p < 0.0001) compared with serum sTfR (p < 0.001), indicating more diagnostic efficacy of the sTfR/F index for CRF with IDA. In conclusion, the serum sTfR concentration is a useful diagnostic tool for discrimination between IDA and ACD, and between AA and MDS-RA, and for the detection of iron deficiency in CRF patients in the Japanese population.

Adult↗
PubMed2002

Diffuse nodular lymphoid hyperplasia of the large bowel without hypogammaglobulinemia or malabsorption syndrome: a case report and literature review.

Diffuse nodular lymphoid hyperplasia (DNLH) of the intestine is an extremely rare lymphoproliferative disorder occasionally associated with non-Hodgkin lymphomas. We report an unusual case of DNLH of the entire colon, which resembled malignant lymphoma (particularly low-grade B-cell lymphoma) both on clinical and pathologic grounds. The patient was a 62-year-old Japanese woman who was found to have multiple polypoid lesions along the entire large intestine by colonoscopy. Abdominal computed tomography revealed hepatosplenomegaly and multiple mesenteric lymphadenopathy. Histologically, the lesion was characterized by numerous lymphoid follicles with active germinal centers and a diffuse infiltrate of lymphoid cells in the mucosa and submucosa. The present case appears to be an essentially benign condition bearing a resemblance, both clinically and histologically, to malignant lymphoma, and from which it can be distinguished by use of immunohistochemical or molecular analysis.

Agammaglobulinemia↗
PubMed2002

LDL-cholesterol and HDL-cholesterol concentrations decrease during the day.

BACKGROUND: Homogenous assays for LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) are highly accurate, with little interference from triglyceride. Using these methods, we measured postprandial LDL-C and HDL-C. Earlier studies suggested a postprandial decrease in LDL-C. METHODS: To elucidate whether LDL-C and HDL-C decrease significantly during the day, we determined daily profiles of LDL-C and HDL-C using homogeneous assays in subjects with normal coronary arteries (N; n=10), and subjects with coronary artery disease (CAD; n=23). RESULTS: In both groups, LDL-C and HDL-C were significantly lower from after breakfast until midnight than they were before breakfast. The next morning, they returned to baseline levels. The mean reduction in LDL-C was 0.09-0.13 mmol/L in N and 0.05-0.20 mmol/L in CAD, while that in HDL-C was 0.02-0.06 mmol/L in N and 0.00-0.05 mmol/L in CAD. CONCLUSION: LDL-C and HDL-C decrease significantly over the course of the day.

Adult↗
PubMed2002

[Small lymphocytic lymphoma during the course of pure red cell aplasia].

A 29-year-old woman was diagnosed as having pure red cell aplasia (PRCA) in 1983. Her serum and IgG inhibited erythroid colony formation of bone marrow cells from a normal individual, suggesting antibody-mediated suppression of erythropoiesis. She was first successfully treated with corticosteroids, azathiopurine and cyclophosphamide. However, she relapsed in 1995 and her anemia became refractory to immunosuppressive therapy. In 1998, she developed systemic lymph node enlargement and was diagnosed as having B-cell small lymphocytic lymphoma. Combination chemotherapy resulted in regression of the lesion, but failed to improve the anemia. In this patient's case, we can speculate that B cells producing autoantibodies against erythroid cells have undergone transformation, or alternatively that the immunosuppressive state caused by the PRCA therapy promoted generation of a neoplastic B cell clone.

Female↗