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Biomedical subjects

S Koizumi

Publications and source records attributed to S Koizumi.

At least 127 records · Page 7Linked to original sources
PubMed1997

Transient association of the phosphotyrosine phosphatase SHP-2 with TrkA is induced by nerve growth factor.

Nerve growth factor (NGF) treatment of rat PC12 pheochromocytoma cells results in an increase in the tyrosine phosphorylation of the NGF receptor, TrkA, leading to differentiation to a neuronal phenotype. Dephosphorylation by protein tyrosine phosphatases (PTPases) is thought to play an important role in regulating this signaling pathway. To identify PTPases that are recruited to the activated TrkA receptor, we used an in-gel PTPase assay to examine the presence of PTPases in TrkA immunoprecipitates. The Src homology 2 domain containing PTPase SHP-2 was found to associate transiently with TrkA following receptor activation, reaching a peak after 1 min of NGF treatment and then decreasing rapidly. The association of SHP-2 with TrkA was accompanied by the tyrosine phosphorylation of SHP-2 and an association of SHP-2 with multiple tyrosine-phosphorylated proteins. In addition, the PTPase activity in SHP-2 immunoprecipitates increased greater than twofold after 1 min of NGF treatment. This is the first demonstration that the association of SHP-2 with TrkA is induced by NGF and that this association leads to SHP-2 activation and tyrosine phosphorylation. We conclude that SHP-2 plays a significant role in early biochemical events in TrkA-mediated signal transduction.

Adrenal Gland Neoplasms↗
PubMed1997

The melanin biosynthesis genes of Alternaria alternata can restore pathogenicity of the melanin-deficient mutants of Magnaporthe grisea.

The phytopathogenic fungi Magnaporthe grisea and Alternaria alternata produce melanin via the polyketide biosynthesis, and both fungi form melanized colonies. However, the site of melanin deposition and the role of melanin in pathogenicity differ between these two fungi. M. grisea accumulates melanin in appressoria, and their melanization is essential for host penetration. On the other hand, A. alternata produces colorless appressoria, and melanin is not relevant to host penetration. We examined whether the melanin biosynthesis genes of A. alternata could complement the melanin-deficient mutations of M. grisea. Melanin-deficient, nonpathogenic mutants of M. grisea, albino (Alb-), rosy (Rsy-), and buff (Buf-), were successfully transformed with a cosmid clone pMRB1 that carries melanin biosynthesis genes ALM, BRM1, and BRM2 of A. alternata. This transformation restored the melanin synthesis of the Alb- and Buf- mutants, but not that of the Rsy- mutant. The melanin-restored transformants regained mycelial melanization, appressorium melanization, and pathogenicity to rice. Further, transformation of Alb- and Buf- mutants with subcloned ALM and BRM2 genes, respectively, also produced melanin-restored transformants. These results indicate that the Alternaria genes ALM and BRM2 can restore pathogenicity to the mutants Alb- and Buf-, respectively, due to their function during appressorium development in M. grisea.

Alternaria↗
PubMed1997

Expression of Bcl-2 in human breast cancer: correlation between hormone receptor status, p53 protein accumulation and DNA strand breaks associated with apoptosis.

The expression of Bcl-2, a suppressor of apoptotic cell death, was investigated in 52 invasive carcinomas of the breast using reverse transcription-polymerase chain reaction and immunohistochemical methods. After consideration of both sets of results, 42 tumors (80.8%) were confirmed to be positive (Bcl-2(+)) and 10 (19.2%) were judged negative (Bcl-2(-)) for Bcl-2 expression. Related factors (p53 protein accumulation, hormone receptor status and apoptotic cell index) were also examined using immunohistochemical and in situ end-labeling methods to elucidate their correlations with Bcl-2 expression. Bcl-2 expression correlated significantly with the hormone receptor status, whereas it showed significant inverse correlations with p53 accumulation and the apoptotic index. It was concluded that estrogen and mutant p53 are related to the regulation of Bcl-2 expression and that the ability to prevent tumor cell death due to Bcl-2 can be developed by breast cancers.

Apoptosis↗
PubMed1997

Treatment of hyperthyroidism with a small single daily dose of methimazole: a prospective long-term follow-up study.

A prospective long-term follow-up study was performed with conventional divided doses (group C: 10 mg 3 times daily, N = 58) and a small single daily dose (group S: 15 mg once daily, N = 54) of methimazole (MMI) for the treatment of Graves' hyperthyroidism. Within 8 weeks, almost 80% of the patients in both groups became euthyroid. The mean time required to achieve a euthyroid state was 5.6 +/- 2.7 weeks in group C and 5.8 +/- 3.1 in group S. TSH binding inhibitor immunoglobulin (TBII) levels before therapy were 44.2 +/- 22.7% and 47.1 +/- 23.9% in group C and group S, respectively. A similar gradual fall in TBII levels was observed in both groups over a two-year period of treatment. MMI doses were gradually reduced to a maintenance dose (5 mg daily) after the patients became euthyroid. The patients were treated for 28 +/- 9 months and were followed up after therapy was stopped (observation period in patients who remained in remission was 12-130 (75 +/- 34) months and the interval to relapse in recurred cases was 1-98 (20 +/- 27) months). The rates of recurrence in group C were 41% at 1 yr, 54% at 2 yrs, 56% at 4 yrs and 61% at 6 yrs. In group S, these were 44%, 53%, 56% and 63%, respectively. No differences between relapse rates were observed with the two different dosage regimens. Adverse effects occurred more frequently in group C patients (24%) than in group S patients (13%). These results show that there is no difference in the clinical and immunological course or in the long-term remission rate of Graves' hyperthyroidism when the treatment is initiated with either a small single daily dose (15 mg) or the conventional regimen (10 mg 3 times daily).

Adult↗
PubMed1997

[A case of polymyalgia rheumatica with swelling and pitting edema of the distal lower extremities].

We report a case of an 82-year-old woman with polymyalgia rheumatica (PMR) associated with swelling and pitting edema of the lower extremities. The patient had been previously admitted because of PMR in 1990, but there was no history of swollen extremities. In July 1996, at another hospital, she was again diagnosed as having PMR on the basis of pain in the neck, shoulders and lower back. Administration of prednisolone was followed by improvement of the symptoms. Four months later, similar pain recurred and swelling of the lower extremities was noted. On admission, the erythrocyte sedimentation rate was 86 mm/h, and C-reactive protein was 15.5 mg/dl. Reviewing the previous treatment, it was ascertained that her clinical deterioration was due to premature reduction of the steroid dosage. The cause of the swelling of the lower extremities was unlikely to be heart, liver, kidney or endocrine disease. Prednisolone was increased from 2.5 mg to 10 mg daily with marked improvement in all the symptoms including the swelling and pitting edema. In 1996, a study reported distal extremity swelling with pitting edema as a manifestation of PMR, which mostly developed concurrently with proximal symptoms or during relapses of PMR. The swelling responded poorly to non-steroidal antiinflammatory drugs but promptly to corticosteroids. The distal swelling was reported to be tenosynovitis and synovitis of the surrounding structures. The present case appears similar to that report. More studies of PMR need to be done.

Aged↗
PubMed1997

[Effects of imagery ability and speech anxiety on imagery vividness of imaginary of speech scene].

Effects of imagery ability and speech anxiety on imagery vividness of imaginary of speech scene were examined. Subjects were divided into four groups in terms of high and low scores of Scale of Mental Imagery-Short Form (SMI-S) and a speech anxiety scale. They imagined themselves in neutral, action and speech scenes. They were asked to rate valence, arousal, and dominance of associated emotion, as well as imagery vividness, of each scene. An SMI-S effect was found on the vividness for neutral and action scenes. For vividness of the speech scene, however, speech anxiety had a stronger effect than imagery ability. The subjects with high speech anxiety significantly decreased imagery vividness, and experienced stronger arousal during imaginary speech. Good-imagery subjects with high speech anxiety reported stronger arousal than poor-imagery subjects. These results suggested that speech anxiety was a major determinant of imagery vividness of imaginary of speech scene.

Adult↗
PubMed1997

[Myelogenous leukemia in children. ANLL9205 study by Children's Cancer and Leukemia Study Group (CCLSG)].

Treatment results were evaluated in 45 children with acute myeloblastic leukemia (AML) treated on the ANLL-9205 protocol of the Children's Cancer Leukemia Study Group (CCLSG, Japan). In this protocol, terarubicin (THP-ADR), vincristine and continuous infusion of cytosine arabinoside (Ara C) were applied for remission induction therapy (AVC), and VP16+ high dose Ara C were used sequentially for 32 or 48 weeks. Eleven patients received stem cell transplantation. Thirty-eight out of the 43 eligible patients (88.4%) achieved complete remission, and the overall 3-year event-free survival (EFS) was 55.6% (S.E.,10%). This favorable response was attributed mainly to the high induction rate of patients with the M5, M7 FAB subtypes and higher WBC counts (> or = 10 x 10(9)/L). There was no difference in the 3-year EFS of these patients who discontinued treatment between 32 weeks and 48 weeks. Serious toxicities were not observed in this study. These findings suggest that the ANLL-9205 protocol is an effective and safe treatment regimen for childhood AML. When comparing the treatment period of 32 or 48 weeks, the difference was not statistically significant.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

[Hemo-lymphangioma of the scrotum: a case report].

A 3-year-old boy was referred because of a painless mass in the left scrotum. On palpation, the mass was discriminated from the testis, epididymis and spermatic cord and showed transillumination. A part of the mass was dark purple in color. Total surgical excision of the mass was performed. The lesion was multicystic (2-15 mm), adherent to the scrotal skin, and easily dissectable from the testicle. Pathological examination revealed lymphangioma as a major component and hemangioma as a minor part. He has been free of recurrent disease for 2 years. This is the 7th case of hemo-lymphangioma of the scrotum in the Japanese literature.

Child, Preschool↗
PubMed1997

[Adenocarcinoma occurring 37 years after augmentation ileocystoplasty for tuberculous bladder atrophy: report of a case].

A 55-year-old woman was admitted with urinary frequency. She had undergone augmentation ileocystoplasty due to tuberculous bladder atrophy 37 years previously. Cystoscopy revealed a tumor on the posterior wall which had been augmented with the ileum. Partial cystectomy and bladder reconstruction using a segment of ileum and ascending colon were performed. Gross inspection showed a 15 x 10 mm, papillary tumor on the ileal mucosa near the vesico-ileal anastomosis. Histologically, moderately differentiated adenocarcinoma infiltrating into the muscle layer was surrounded by the normal ileal mucosa. She has been free of recurrence for 2 years postoperatively. This is the 8th case of adenocarcinoma following augmentation ileocystoplasty reported in the Japanese literature.

Adenocarcinoma↗
PubMed1997

[Treatment results of intermittent and cyclic regimen with ATRA and chemotherapy in childhood acute promyelocytic leukemia. Children's Cancer and Leukemia Study Group].

An intermittent and cyclic regimen with All-Trans Retinoic Acid (ATRA) and intensive chemotherapy was conducted due to pharmacokinetic studies on ATRA for acute promyelocytic leukemia (APL) in children. We have treated 17 children with APL using ATRA for remission induction followed by an intermittent schedule of ATRA plus intensive chemotherapy (APL-ATRA protocol). There were 10 males and 7 females. The median age was 9.0 years old. The median baseline white blood cell count was 12.1 x 10(3)/microliter, hemoglobin 7.8 g/dl, platelet 4.5 x 10(4) microliters at diagnosis. Sixteen patients showed t(15; 17) translocation. RT-PCR analysis was available in 15 patients and showed PML/RAR alpha rearrangement in all patients. Overall, 13 or 17 newly diagnosed patients (88%) achieved complete remission and EFS was 67%. Compared to the control (same chemotherapy without ATRA regimen), remission induction and EFS were significantly increased. The toxicity of ATRA consisted of retinoic acid syndrome in 1 and pseudotumor cerebli in another. Other toxicities included headache, chelitis, gastrointestinal trouble and bone pain. These results suggest that intermittent and cyclic regimen with ATRA and intensive chemotherapy (APL-ATRA protocol) is highly effective for APL patients.

Aclarubicin↗
PubMed1996

SHP-2 is involved in neurotrophin signaling.

To investigate the involvement of SHP-2 in the signal transduction pathway stimulated by neurotrophins, the association of SHP-2 with components of the pathway was examined. Following NGF stimulation of PC12 cells, SHP-2 was found to be associated with the p85 subunit of PI3-kinase and the Shc proteins. In retinoic acid-differentiated SH-SY5Y cells and primary cultures of rat cortical neurons, BDNF treatment similarly caused the association of SHP-2 with p85. In addition, a tyrosine-phosphorylated protein, which is probably TrkB, was coimmunoprecipitated with SHP-2 in both cultures. These results show that SHP-2 becomes associated with signaling proteins after treatment with neurotrophins and suggest that SHP-2 plays a fundamental role in neurotrophin signaling.

Animals↗
PubMed1996

Inhibition by antipsychotic drugs of L-type Ca2+ channel current in PC12 cells.

Inhibition by antipsychotic drugs of voltage-gated L-type Ca2+ channels was characterized in rat neuronal cell line pheochromocytoma PC12 cells. Under whole-cell voltage-clamp, haloperidol and chlorpromazine (1-100 microM) inhibited Ba2+ current permeating through Ca2+ channels. Fluspirilene and pimozide the Ba2+ current at lower concentrations (fluspirilene, 0.1 pM to 1 nM; pimozide 10 pM to 1 microM). Effects of dopamine receptor antagonists and calmodulin antagonists were tested because antipsychotic drugs are known to exhibit these pharmacological activities. Sulpiride (1 and 10 microM), an antagonist to dopamine D2 receptors, and SCH-23390 (R(+)-7-chloro-8-hydroxy-3-methyl-l-phenyl-2,3,4,5-tetrahydro-1H-3- benzazepine; 1 and 10 microM), an antagonist to dopamine D1 receptors, also inhibited the Ba2+ current. As for calmodulin antagonists, W-7 (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide; 10 and 100 microM) as well as calmidazolium (10 nM to 1 microM) reduced the Ba2+ current. The inhibition by haloperidol or fluspirilene of the Ba2+ current was not affected when GTP in intracellular solution was replaced with GDP beta S. These properties of the Ca2+ channel inhibition are discussed by comparing with those of the K+ channel inhibition and in relation to therapeutic relevance.

Animals↗
PubMed1996

Epstein-Barr virus (EBV)-carrying and -expressing T-cell lines established from severe chronic active EBV infection.

Four novel Epstein-Barr virus (EBV)-carrying T-cell lines, designated SIS, AIK-T8, AIK-T4, and SKN, were established from peripheral blood lymphocytes (PBL) of patients with severe chronic active EBV infection, in the presence of interleukin-2 and 4-deoxyphorbol ester. AIK-T8 and -T4 were derived from a single patient. Cell marker and genotype analyses showed that SIS, AIK-T8, and AIK-T4 had mature T-cell phenotypes with clonally rearranged T-cell receptor (TCR) genes, whereas SKN had an immature T-cell phenotype without TCR gene rearrangement. None of the cell lines expressed B, natural killer, or myeloid antigens or had Ig gene rearrangement. All lines carried EBV genomes in a single episomal form. SIS, AIK-T8, and SKN showed the same phenotype, TCR gene configuration, and/or EBV clonotype as their source or biopsied materials; therefore, they represented EBV-infected T cells proliferating in the patients. TCR gene and EBV episomal structures similar to those of AIK-T4 were not found in its source PBL, probably due to the few parental clones in vivo. All lines expressed EBV-encoded small RNA (EBER) 1, nuclear antigen (EBNA) 1, and latent membrane protein (LMP) 1, -2A, and -2B, but not other EBNAs that could be recognized by EBV-specific immune T cells. EBV replicative antigens were rarely expressed or induced. Such EBV latency reflects the in vivo situation, in which the T cells may evade immune surveillance and be insensitive to antiherpesvirus drugs. Collectively, the data suggest that EBV can target and latently infect T cells at any stage of differentiation in vivo, thus potentially causing uncontrolled T-cell proliferation. These cell lines will facilitate further analyses of possible EBV-induced oncogenicity in T cells.

Base Sequence↗
PubMed1996

Internal stenting of the hepaticojejunostomy and pancreaticojejunostomy in patients undergoing pancreatoduodenectomy to promote earlier discharge from hospital.

Internal stenting of the hepaticojejunostomy and pancreaticojejunostomy was performed in 11 consecutive patients undergoing pancreatoduodenectomy between July 1992, and July 1994, to promote earlier discharge from hospital. Although minor leakage of the pancreaticojejunostomy occurred in 4 patients, this resolved within a short period and all 11 patients were able to be discharged by the 29th postoperative day in good health and without any intubation. Follow-up abdominal X-ray and computed tomography (CT) scans proved that all 22 of the stenting tubes had spontaneously fallen out by the 176th postoperative day. No complication related to the stenting tubes occurred in any of our patients.

Adult↗
PubMed1996

Nerve growth factor induces resistance of PC12 cells to nitric oxide cytotoxicity.

Nitric oxide (NO) donors, sodium nitroprusside and NOC 7, caused pheochromocytoma (PC12) cell death in a concentration and time-dependent manner. This cytotoxicity was blocked by the NO trapping agent, oxyhemoglobin. A membrane permeable cGMP analogue had no cytotoxicity in a reasonable concentration. Moreover, the selective inhibitor of cGMP-dependent protein kinase, KT5823, had no effect on NOC 7 cytotoxicity. These results suggest that NO caused PC12 cell death but not through the cGMP pathway. Additionally, this NO-induced PC12 cell death is not accompanied by DNA fragmentation. Nerve growth factor (NGF), which is able to rescue PC12 cells from serum deprivation, failed to protect PC12 cells from NO-induced cell death by acute treatment. However, PC12 cells differentiated by NGF treatment for more than 3 days did not die after NO exposure. The differentiated PC12 cells, but not undifferentiated cells, expressed NO synthase (NOS). NGF-differentiated PC12 cells acquired the resistance to NO, by a mechanism not yet identified, accompanied by the expression of NOS.

Animals↗