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Dive into the research topics where Tadashi Maehara is active.

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Featured researches published by Tadashi Maehara.


British Journal of Haematology | 1994

Clonality in chronic myeloproliferative disorders defined by X-chromosome linked probes: demonstration of heterogeneity in lineage involvement

Norifumi Tsukamoto; Kimio Morita; Tadashi Maehara; Kiyoshi Okamoto; Hirotaka Sakai; Masamitsu Karasawa; Takuji Naruse; Mitsuhiro Omine

Summary The restriction fragment length polymorphisms (RFLP) of the X‐chromosome phosphoglycerate kinase (PGK) and hypoxanthine phosphoribosyltransferase (HPRT) genes were used to study the clonal basis of the chronic myeloproliferative disorders (CMPD). Analyses were performed on granulocyte and T‐lymphocyte fractions obtained from 24 females; 13 had essential thrombocythaemia (ET), eight polycythaemia vera (PV) and three myelofibrosis with myeloid metaplasia (MMM). All 24 of these patients had monoclonal patterns of X‐inactivation in the granulocyte fraction. For the T‐lymphocyte fraction, non‐clonal patterns of Xinactivation were observed in 8/13 patients with ET, 7/8 with PV and 1/3 with MMM, while the remaining eight subjects were found to have monoclonal patterns of N inactivation. Our findings suggest that the majority of the CMPD in these patients originated from a relatively committed progenitor cell without the capacity to differentiate into T cells, and convincingly demonstrated heterogeneity of lineage involvement.


British Journal of Haematology | 1993

Clonality in myelodysplastic syndromes: demonstration of pluripotent stem cell origin using X‐linked restriction fragment length polymorphisms

Norifumi Tsukamoto; Kimio Morita; Tadashi Maehara; Kiyoshi Okamoto; Masamitsu Karasawa; Mitsuhiro Omine; Takuji Naruse

Restriction fragment length polymorphisms (RFLP) of the X‐chromosome genes phosphoglycerate kinase (PGK) and hypoxanthine phorphoribosyltransferase (HPRT) were used to determine the clonal nature of myelodysplastic syndromes (MDS) in 22 patients. These included eight with refractory anaemia (RA), four with RA with ring sideroblasts (RARS), six with RA with an excess of blasts (RAEB), three with RAEB in transformation (RAEB‐T), and one with chronic myelomonocytic leukaemia (CMML). Monoclonal X‐inactivation patterns were observed in 19/22 patients. The remaining three cases, one each with RA, RARS and RAEB, were of polyclonal composition. Separated T‐lymphocyte and granulocyte fraction analyses in six patients of the former cases revealed that T‐lymphocyte as well as granulocyte fractions showed a monoclonal pattern of X‐inactivation. These results support the view that the majority of MDS arise from a pluripotent stem cell capable of myeloid and lymphoid differentiation.


Scandinavian Journal of Rheumatology | 2000

Adult Still's disease as a paraneoplastic manifestation of breast cancer

Junko Neishi; Yoshito Tsukada; Tadashi Maehara; Kazue Ueki; Akira Maezawa; Yoshihisa Nojima

We treated a patient who developed symptoms and findings indistinguishable from those of adult Stills disease as a manifestation of metastatic breast cancer 7 years after treatment for a stage 1 tumor. Although clinical features fulfilled diagnostic criteria for adult Stills disease, examination of a bone marrow biopsy specimen indicated that the apparent adult Stills disease was a paraneoplastic manifestation associated with diffuse marrow infiltration by breast cancer. The fever and polyarthralgia resolved with administration of prednisolone, and antiestrogen therapy with tamoxifen citrate was also started.We treated a patient who developed symptoms and findings indistinguishable from those of adult Stills disease as a manifestation of metastatic breast cancer 7 years after treatment for a stage 1 tumor. Although clinical features fulfilled diagnostic criteria for adult Stills disease, examination of a bone marrow biopsy specimen indicated that the apparent adult Stills disease was a paraneoplastic manifestation associated with diffuse marrow infiltration by breast cancer. The fever and polyarthralgia resolved with administration of prednisolone, and antiestrogen therapy with tamoxifen citrate was also started.


International Journal of Hematology | 2001

Analysis of the distribution of CAG repeats and X-chromosome inactivation status of HUMARA gene in healthy female subjects using improved fluorescence-based assay.

Masamitsu Karasawa; Norifumi Tsukamoto; Arito Yamane; Kiyoshi Okamoto; Tadashi Maehara; Akihiko Yokohama; Yoshihisa Nojima; Mitsuhiro Omine

We investigated the polymorphic CAG-repeat distribution and the X-inactivation status of the human androgen receptor (HUMARA) gene in 58 female Japanese volunteers. Polymerase chain reaction amplification was performed using a fluorescent-dye-labeled primer under conditions specific for GC-rich targets, and fragments were analyzed. To estimate the length of these fragments, FAM-labeled (blue fluorescent) products were simultaneously compared with ROM-labeled size markers (red) that were created by sequencing various HUMARA fragments. The number of polymorphic CAG repeats of HUMARA in 116 alleles from 58 female subjects ranged from 15 to 28. Of the 58 volunteers, 51 (88.0%) were heterozygous. In 96% of the heterozygous female subjects, the allelic differences were no greater than 6 repeats. X-chromosome inactivation was calculated as the ratio of the area of the smaller peak to the sum of the areas of the smaller and larger peaks. The average ratio was 0.38 (range, 0.09-0.50). Preferential use of 1 allele, by more than 75% (ratio, <0.25), was observed in 5 volunteers (10.9%). The clonal nature of a patient with chronic myelogenous leukemia was easily identified. This method is sensitive enough to discriminate a difference of 1 triplet repeat.


American Journal of Hematology | 1999

Myelodysplastic syndromes with nephrotic syndrome

Takayuki Saitoh; Hirokazu Murakami; Hideki Uchiumi; Kazuaki Moridaira; Tadashi Maehara; Takafumi Matsushima; Norifumi Tsukamoto; Jun'ichi Tamura; Masamitsu Karasawa; Takuji Naruse; Jun Tsuchiya

It is sometimes reported that the immunological abnormalities in myelodysplastic syndromes (MDS) induce autoimmune disease (i.e., acute systemic vasculitic syndrome, chronic cutaneous vasculitis, polyneuropathy, relapsing polychondritis, and steroid‐responsive pulmonary disorders). We investigated the clinical features of patients with MDS accompanied by nephrotic syndrome. We enrolled 125 patients with MDS who were admitted between January 1979 and May 1996 in this study. The renal function was assessed based on the laboratory data and the findings at the physical examination. The diagnoses of nephrotic syndrome and glomerular disease were established when 24‐hr urinary excretion was more than 3.5 g and serum total protein was less than 6.0 g/dl, and when the 24‐hr protein excretion was more than 1.5 g. Five patients (4%) had glomerular disease, and three (2.4%) had nephrotic syndrome. Of the five patients with glomerular disease, two had refractory anemia (RA), and three had chronic myelomonocytic leukemia (CMMOL). Three of the total 11 patients with CMMOL were diagnosed as having nephrotic syndrome. Among the CMMOL patients, those with nephrotic syndrome showed higher absolute monocyte numbers than did those without nephrotic syndrome (8830 ± 4677/μl vs. 3061 ± 2887/μl, P = 0.03). One CMMOL patient was treated with VP‐16 and hydroxyurea. As the white blood cell count in this patient decreased, the 24‐hr urine protein excretion and the serum tumor necrosis factor alpha level decreased. The relationship between nephrotic syndrome and CMMOL was not clear. High monocyte count and the serum cytokines in MDS patients may play a partial role in the evolution of glomerulonephritis, and CMMOL may be closely related to nephrotic syndrome. Am. J. Hematol. 60:200–204, 1999.


Leukemia Research | 1996

Detection of c-myc oncogene amplification in a CML blastic phase patient with double minute chromosomes

Masamitsu Karasawa; Kiyoshi Okamoto; Tadashi Maehara; Norifumi Tsukamoto; Kimio Morita; Takuji Naruse; Mitsuhiro Omine

Double minute chromosomes (dmin) are relatively rare in leukemias. Cytogenetic analysis of blood cells from a woman with blastic phase chronic myelogenous leukemia (BC-CML) showed numerous dmin chromosomes and complex abnormalities including a Philadelphia (ph(1))-chromosome. Oncogene amplification in hematopoietic malignancies is also rare. Using PCR, we retrospectively investigated the extent of c-myc gene amplification in DNA extracted from stored blood smears from the patient. To qualify the PCR products, the beta-globin gene was used as the internal reference gene and it was co-amplified with the c-myc gene. The extent of amplified c-myc was about 6.8-fold. This finding suggests that the c-myc gene was amplified in dmin and that the gene amplification contributes to the progression to acute leukemia or rapid growth of leukemic cells.


Annals of Hematology | 1996

The majority of T lymphocytes are polyclonal during the chronic phase of chronic myelogenous leukemia

Norifumi Tsukamoto; Masamitsu Karasawa; Tadashi Maehara; Kiyoshi Okamoto; Hirotaka Sakai; Takuji Naruse; Kimio Morita; Jun Tsuchiya; Mitsuhiro Omine

To clarify the extent of cell lineage involvement in chronic myelogenous leukemia (CML), we investigated the bcr gene rearrangement and clonality using the X-chromosome-linked restriction fragment length polymorphism (RFLP) methylation method in T lymphocytes and granulocytes. We examined the granulocyte and T-cell fractions from the peripheral blood of seven female patients with CML during the chronic phase; patients were heterozygous for RFLPs at the phosphoglycerate kinase (PGK) or the hypoxanthine phosphoribosyltransferase (HPRT) gene. RFLP-methylation analysis of granulocytes demonstrated a monoclonal pattern in six of the seven patients and a rearrangedbcr gene in all seven patients. In contrast, T lymphocytes exhibited a polyclonal pattern in six cases; in one case, a faint band was observed following methyl-sensitive enzyme cleavage. Thebcr gene analysis in T lymphocytes showed the germline in every case. Our results indicate that the majority of T lymphocytes are polyclonal during the chronic phase of CML and confirm previous reports based on glucose-6-phosphate dehydrogenase, cytogenetic, andbcr rearrangement analyses.


International Journal of Hematology | 2002

Acute Basophilic Leukemia Lacking Basophil-Specific Antigens: The Importance of Cytokine Receptor Expression in Differential Diagnosis

Akihiko Yokohama; Norifumi Tsukamoto; Nahoko Hatsumi; Miwa Suto; Tohru Akiba; Hideki Uchiumi; Tadashi Maehara; Takafumi Matsushima; Masamitsu Karasawa; Hirokazu Murakami; Shougo Shinonome; Hirohisa Saito; Yoshihisa Nojima

De novo acute basophilic leukemia (ABL) is a rare form of myeloid leukemia. The low prevalence of ABL makes it difficult to define its clinical characteristics and to establish an effective therapeutic protocol. We present here a case of de novo ABL in a 64-year-old Japanese man. The diagnosis of ABL depended on the following: (1) metachromasia with toluidine blue stain, (2) intracytoplasmic theta granules identified by electron microscopy, and (3) findings obtained from extensive immunophenotypic analysis. Although blast cells lacked basophil-specific antigens such as CDw17, CD88, and FcεRI, an expression profile of cytokine receptors including CD116 (GM-CSF receptor), CD117 (c-kit), and CD123 (IL-3 receptor α) helped to define the cellular lineage in our case. The patient achieved complete remission with intensive chemotherapy composed of idarubicin and cytosine arabinoside and was disease free during the following 30 months. We propose that immunophenotyping, especially focusing on cytokine receptors, is useful in diagnosing ABL.


American Journal of Hematology | 2000

Multiple Myeloma Presenting High Fever and High Serum Levels of Lactic Dehydrogenase, CRP, and Interleukin-6

Hirokazu Murakami; Satoru Takada; Nahoko Hatsumi; Akihiko Yokohama; Takayuki Saitoh; Hideki Uchiumi; Tadashi Maehara; Takafumi Matsushima; Norifumi Tsukamoto; Kimio Morita; Jun'ichi Tamura; Morio Sawamura; Masamitsu Karasawa

Two myeloma patients presented high fever with no signs or data indicating infection at diagnosis or relapse. Both patients had plasmablastic myeloma, and serum levels of lactic dehydrogenase (LDH) and CRP were extremely high. Plasmablastic morphology, high LDH, and CRP were recognized as poor prognostic factors, indicating a fulminant phase of multiple myeloma. Interleukin‐6 (IL‐6) was only high in measured cytokines. We proposed that IL‐6 caused high fever and induced the fulminant phase in these 2 cases. Am. J. Hematol. 64:76–77, 2000.


British Journal of Haematology | 2002

Enhanced haemolysis with β‐thalassaemia trait due to the unstable β chain variant, Hb Gunma, accompanied by hereditary elliptocytosis due to protein 4·1 deficiency in a Japanese family

Tadashi Maehara; Norifumi Tsukamoto; Yoshihisa Nojima; Masamitsu Karasawa; Hirokazu Murakami; Yukio Hattori; Hiroshi Ideguchi

Summary. We identified a Japanese family with a β‐thalassaemia trait and hereditary elliptocytosis (HE). We studied five members of this family. One was normal, one had only the β‐thalassaemia trait, one had heterozygous HE, and two had compound heterozygous β‐thalassaemia trait and HE. The last two had already undergone splenectomy. The molecular profile of β‐thalassaemia was consistent with that of Hb Gunma: codon 127/128CAGGCT(Gln–Ala)→ CCT(Pro). Analysis of erythrocyte membrane proteins revealed a partial deficiency of protein 4·1 in all those with HE, whereas the spectrin content was within the normal range. Each heterozygous family member with either the β‐thalassaemia trait or HE was asymptomatic, whereas the two with both β‐thalassaemia and HE had marked red blood cell deformities and haemolysis. The abnormalities of the red blood cells in patients with the β‐thalassaemia trait might be enhanced by association with HE owing to a protein 4·1 deficiency.

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