Publications by authors named "Amasaki Y"

Carbon ion radiotherapy (CIRT) for pediatric cancer is currently limited because of the unknown risk of induction of secondary cancers. Medulloblastoma of Ptch1+/- mice offers a unique experimental system for radiation-induced carcinogenesis, in which tumors are classified into spontaneous and radiation-induced subtypes based on their features of loss of heterozygosity (LOH) that affect the wild-type Ptch1 allele. The present study aims to investigate in young Ptch1+/- mice the carcinogenic effect, and its age dependence, of the low-linear energy transfer (LET, ∼13 keV/µm) carbon ions, to which normal tissues in front of the tumor are exposed during therapy.

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Recent studies have identified interstitial deletions in the cancer genome as a radiation-related mutational signature, although most of them do not fall on cancer driver genes. Pioneering studies in the field have indicated the presence of loss of heterozygosity (LOH) spanning Apc in a subset of sporadic and radiation-induced intestinal tumors of ApcMin/+ mice, albeit with a substantial subset in which LOH was not detected; whether copy number losses accompany such LOH has also been unclear. Herein, we analyzed intestinal tumors of C3B6F1 ApcMin/+ mice that were either left untreated or irradiated with 2 Gy of γ-rays.

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Calorie restriction (CR) suppresses not only spontaneous but also chemical- and radiation-induced carcinogenesis. Our previous study revealed that the cancer-preventive effect of CR is tissue dependent and that CR does not effectively prevent the development of thymic lymphoma (TL). We investigated the association between CR and the genomic alterations of resulting TLs to clarify the underlying resistance mechanism.

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Rationale: Multicentric Castleman disease (MCD) is a rare lymphoproliferative disorder accompanied by systemic symptoms characterized by polyclonal hypergammaglobulinemia and chronic inflammation due to overexpression of interleukin-6. Histological heterogeneity of renal involvement in MCD has been described, although the number of reports is limited. Tocilizumab, a humanized anti-interleukin-6 receptor antibody, has been reported to be effective for MCD.

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Neutron radiation, a high-linear energy transfer radiation, has a high relative biological effectiveness (RBE) for various end points. The age at exposure is an important modifier of the effects of radiation, including carcinogenesis, with infants being generally more radiosensitive. Ptch1+/- mice offer a unique experimental system for assessing radiation carcinogenesis.

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Aims: We compared the incidence of adverse events between single and divided-dose regimens of methotrexate (MTX) by using a multicenter randomized controlled trial.

Methods: Eighty-nine patients with insufficient control on MTX 8 mg/wk were randomly assigned into single-dose (39 patients) or triple dose (39 patients) groups. The MTX dose for all patients was gradually increased to 16 mg/wk.

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Objective: No evidence has shown the efficacy of Sodium Risedronate (Risedronate) for glucocorticoid-induced osteoporosis (GIO) in patients with Rheumatoid arthritis (RA). The aim of this study was to explore the effectiveness and safety of Risedronate for GIO complicated with RA.

Methods: This was a six-month randomized, double-blind, placebo-controlled trial of 95 patients with GIO complicated with RA from 19 centers.

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Objectives: To clarify the efficacy and safety of calcineurin inhibitors (CNI) for treating adult-onset Still's disease (AOSD).

Methods: This multicentre historical cohort study enrolled the consecutive patients with AOSD according to Yamaguchi classification criteria. The endpoints were set as the time from the initiation of treatment to events, the persistency rate of CNI and safety.

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Ionizing radiation can damage DNA and, therefore, is a risk factor for cancer. Eker rats, which carry a heterozygous germline mutation in the tumor-suppressor gene tuberous sclerosis complex 2 (Tsc2), are susceptible to radiation-induced renal carcinogenesis. However, the molecular mechanisms involved in Tsc2 inactivation are unclear.

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Biallelic germline mutations in the DNA mismatch repair gene MLH1 lead to constitutional mismatch repair-deficiency syndrome and an increased risk for childhood hematopoietic malignancies, including lymphoma and leukemia. To examine how Mlh1 dysfunction promotes lymphoma as well as the influence of ionizing radiation (IR) exposure, we used an Mlh1-/- mouse model and whole-exome sequencing to assess genomic alterations in 23 T-cell lymphomas, including 8 spontaneous and 15 IR-associated lymphomas. Exposure to IR accelerated T-cell lymphoma induction in the Mlh1-/- mice, and whole-exome sequencing revealed that IR exposure neither increased the number of mutations nor altered the mutation spectrum of the lymphomas.

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Extraintestinal infections due to Clostridium difficile are uncommon. When such infections occur, extraintestinal C. difficile isolates are usually identical to fecal isolates.

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Objectives: To preliminarily evaluate the feasibility of maintenance therapy with reduced dose of intravenous abatacept (ABT) to 250 mg/body/month after achieving remission or low disease activity (LDA).

Patients And Methods: RA patients treated with ABT at 13 sites were enrolled in this prospective interventional pilot study during the period between March 2013 and March 2015. Inclusion criteria were (1) age at 20 years or older, (2) under treatment with monthly intravenous ABT at approved doses, (3) DAS28-CRP lower than 2.

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In October 2012, a man in his 60s was hospitalized for the examination of ascites, and was diagnosed with gastric cancer and carcinomatous peritonitis. S-1+cisplatin (CDDP) therapy was administered as neoadjuvant chemotherapy; however, during therapy, he developed cerebral infarction. We suspected that the cerebral infarction was caused by a coagulation disorder owing to Trousseau's syndrome.

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Children are considered more sensitive to radiation-induced cancer than adults, yet any differences in genomic alterations associated with age-at-exposure and their underlying mechanisms remain unclear. We assessed genome-wide DNA copy number and mutation of key tumor suppressor genes in T-cell lymphomas arising after weekly irradiation of female B6C3F1 mice with 1.2Gy X-rays for 4 consecutive weeks starting during infancy (1 week old), adolescence (4 weeks old) or as young adults (8 weeks old).

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Article Synopsis
  • Monitoring mice exposed to carbon ion radiotherapy offers insights into the potential risk of developing second cancers in normal tissues, a concern that can't be assessed solely through historical patient data.
  • The study involved analyzing T cell lymphomas from mice exposed to either carbon ions or gamma rays, focusing on genetic alterations linked to radiation-induced cancer.
  • A significant finding was the presence of large interstitial deletions in the genomes of tumors from carbon ion exposure, which were rarely seen in those exposed to gamma rays, highlighting differences in radiation effects on DNA.
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Ionizing radiation is a well-known carcinogen, but its potency may be influenced by other environmental carcinogens, which is of practical importance in the assessment of risk. Data are scarce, however, on the combined effect of radiation with other environmental carcinogens and the underlying mechanisms involved. We studied the mode and mechanism of the carcinogenic effect of radiation in combination with N-ethyl-N-nitrosourea (ENU) using doses approximately equal to the corresponding thresholds.

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Cancer risk associated with radiation exposure is considered the result of concurrent exposure to other natural and manmade carcinogens. Available data on the molecular characteristics of cancer after simultaneous exposure to radiation and chemicals are insufficient. In our study, we used a mouse thymic lymphoma (TL) model that was synergistically induced by simultaneous exposure to X-rays and N-ethyl-N-nitrosourea (ENU) at subcarcinogenic doses and analyzed the mutation frequency and spectrum of the TL-associated genes Ikaros, Notch1, p53 and Kras.

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This study presents a patient who died of acute renal failure (ARF) as a complication of scleroderma. The patient remained normotensive throughout the clinical course. Myeloperoxidase-anti-neutrophil cytoplasmic antibody was negative.

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In this study, we enrolled early rheumatoid arthritis (RA) patients at multiple institutes who fulfilled the American Rheumatism Association 1987 revised criteria for the classification of RA, and followed the clinical results of disease-modifying anti-rheumatic drug (DMARD) treatment prospectively. With the aim of developing therapeutic guidelines using the disease activity score 28 (DAS28) as disease indices, we investigated the usefulness of bucillamine (BUC), one of the most widely used DMARDs in Japan. Eighty-one patients with early RA who had not previously been treated with DMARDs were suitable for BUC therapy as first-choice treatment.

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Cyclosporin A and tacrolimus have been used as immunosuppressive agents initially in organ transplantation after their discovery, and are also used for treatment of the autoimmune disease, providing an excellent therapeutic effect. These agents act targeting on intracellular phosphatase calcineurin (CN), and subsequently inhibit activation of nuclear factor of activated T cells (NFAT), a key regulator of stimulation-dependent gene activation. The CN-NFAT system is involved not only in the immunoregulation including activation and development of helper T cells, regulatory T cells and NKT cells, but in a variety of cellular and developmental events other than immune system.

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Accurate cancer risk assessment of low-dose radiation poses many challenges that are partly due to the inability to distinguish radiation-induced tumors from spontaneous ones. To elucidate characteristic features of radiation-induced tumors, we analyzed 163 medulloblastomas that developed either spontaneously or after X-ray irradiation at doses of 0.05-3 Gy in Ptch1 heterozygous mice.

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