Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Ritsuko Seki is active.

Publication


Featured researches published by Ritsuko Seki.


Cancer Science | 2009

Prognostic impact of immunohistochemical biomarkers in diffuse large B-cell lymphoma in the rituximab era.

Ritsuko Seki; Koichi Ohshima; Tomoaki Fujisaki; Naokuni Uike; Fumio Kawano; Hisashi Gondo; Shigeyoshi Makino; Tetsuya Eto; Yukiyoshi Moriuchi; Fumihiro Taguchi; Tomohiko Kamimura; Hiroyuki Tsuda; Ryosuke Ogawa; Kazuya Shimoda; Kiyoshi Yamashita; Keiko Suzuki; Hitoshi Suzushima; Kunihiro Tsukazaki; Masakazu Higuchi; Atae Utsunomiya; Masahiro Iwahashi; Yutaka Imamura; Kazuo Tamura; Junji Suzumiya; Minoru Yoshida; Yasunobu Abe; Tadashi Matsumoto; Takashi Okamura

We evaluated the usefulness of prognostic markers in patients with diffuse large B‐cell lymphoma (DLBCL) treated with cyclophosphamide, vincristine, doxorubicin, and prednisolone (CHOP) ± rituximab (R‐CHOP) in Japan. We studied 730 patients with DLBCL; 451 received CHOP and 279 R‐CHOP. We analyzed biopsy samples immunohistochemically for markers of germinal center B cells (CD10, Bcl‐6), postgerminal center B cells (Multiple myeloma‐1), and apoptosis (Bcl‐2). The median follow‐up period for surviving patients was 56.4 months for the CHOP group and 25.2 months for the R‐CHOP group. DLBCL were categorized as germinal center B (GCB) subtype (352/730; 48.2%) or non‐GCB subtype (378/730; 51.8%). In the CHOP group, the high expression of CD10 (P = 0.022) or Bcl‐6 (P = 0.021), or GCB subtype (P = 0.05) was associated with better overall survival, whereas the high expression of Bcl‐2 (P = 0.001) or MUM1 (P = 0.011), or non‐GCB subtype (P = 0.05) was associated with worse overall survival. In the R‐CHOP group, however, these biomarkers except Bcl‐6 were not significant prognostic factors. The patients with non‐GCB subtype showed improved survival in the R‐CHOP group (P = 0.756). The International Prognostic Index was a useful clinical marker of survival in the CHOP group (P < 0.001) and also in the R‐CHOP group (P < 0.001). Results of improved survival with rituximab addition indicate that the relevance of previously recognized prognostic factors should be re‐evaluated. (Cancer Sci 2009; 100: 1842–1847)


International Journal of Hematology | 2008

Periostin and bone marrow fibrosis

Eijiro Oku; Taisuke Kanaji; Yuka Takata; Koichi Oshima; Ritsuko Seki; Satoshi Morishige; Rie Imamura; Korenori Ohtsubo; Michitoshi Hashiguchi; Koichi Osaki; Kazuaki Yakushiji; Kohji Yoshimoto; Hideaki Ogata; Hirofumi Hamada; Kenji Izuhara; Michio Sata; Takashi Okamura

Periostin is a secreted protein that shares structural homology with the insect axon guidance protein fasciclin 1. Periostin is expressed predominantly in collagen-rich fibrous connective tissues that are subjected to constant mechanical stresses. We have shown previously that periostin is a novel component of subepithelial fibrosis in bronchial asthma. Here, we investigated the relationship between periostin and bone marrow (BM) fibrosis. Periostin was expressed in the stroma and stromal cells of BM fibrosis specimens and to a great extent its expression levels correlated closely to the grade of fibrosis, as estimated by silver staining. However, in the present study, we found no relationship between plasma periostin levels and the extent of BM fibrosis. We also demonstrated that periostin is secreted by human BM hTERT stromal cells and that its secretion is enhanced by TGF-β, a cytokine produced by clonal proliferation of megakaryocytes and/or monocytes. These results indicate that periostin is a component of BM fibrosis and that it may play a role in the disease progression.


Leukemia Research | 2012

The Hans algorithm is not prognostic in patients with diffuse large B-cell lymphoma treated with R-CHOP.

Jorge J. Castillo; Brady Beltran; Moo-Kon Song; Ivana Ilic; Sirpa Leppä; Heidi Nurmi; Ritsuko Seki; Silvia Uccella; Jun-Min Li; Diana O. Treaba; Dariusz Stachurski; James N. Butera

Our objective was to evaluate the non-germinal center (GC) profile as a marker for response and survival in DLBCL and to compare the characteristics of patients with GC and non-GC DLBCL treated with rituximab-containing regimens. In this patient-level meta-analysis, retrospective data from 712 newly diagnosed DLBCL patients treated with chemoimmunotherapy from 7 centers were analyzed. GC and non-GC profiles were defined according to the Hans algorithm. Although the non-GC profile showed a trend towards worse overall survival (HR 1.24, 95% CI 0.92-1.66; p=0.15) and progression-free survival (HR 1.29, 95% CI 0.96-1.73; p=0.09), it did not retain its value in the multivariate survival analysis. Additionally, the non-GC profile was independently associated with worse complete response rates (OR 0.55, 95% CI 0.37-0.83; p<0.01) in the multivariate logistic regression analysis. Interestingly, Asian patients had higher proportion of GC DLBCL (p=0.01).


Annals of Oncology | 2010

Prognostic significance of S-phase kinase-associated protein 2 and p27kip1 in patients with diffuse large B-cell lymphoma: effects of rituximab

Ritsuko Seki; Koichi Ohshima; Tomoaki Fujisaki; Naokuni Uike; Fumio Kawano; Hisashi Gondo; Shigeyoshi Makino; Tetsuya Eto; Yukiyoshi Moriuchi; Fumihiro Taguchi; Tomohiko Kamimura; Hiroyuki Tsuda; Kazuya Shimoda; Takashi Okamura

BACKGROUND The F-box protein S-phase kinase-associated protein 2 (Skp2) positively regulates the G1-S transition by promoting degradation of the cyclin-dependent kinase inhibitor p27(kip1) (p27). Recent evidence has indicated an oncogenic role of Skp2 in not only carcinogenesis but also lymphomagenesis. MATERIALS AND METHODS Clinicopathologic features and immunohistochemical expression of Skp2 and p27 were studied retrospectively in 671 patients treated with cyclophosphamide, vincristine, doxorubicin and prednisolone (CHOP) or cyclophosphamide, vincristine, doxorubicin and prednisolone plus rituximab (R-CHOP). The median follow-up periods were 43.2 months in the CHOP group (n = 425) and 24.0 months in the R-CHOP group (n = 246). RESULTS High Skp2 or low p27 expression correlated significantly with poor overall survival (OS) and progression-free survival (P < 0.001) in both treatment groups. The prognostic value of Skp2 or p27 expression was independent of the parameters included in the International Prognostic Index by multivariate analysis. Patients with high Skp2 expression in combination with low p27 expression showed the worst survival. CONCLUSIONS Addition of rituximab to the CHOP regimen did not provide a beneficial outcome to patients with diffuse large B-cell lymphoma with high Skp2 expression and low p27 expression. Skp2 and p27 may be useful prognostic markers in the rituximab era.


Atherosclerosis | 2013

Platelet-derived microparticles augment the adhesion and neovascularization capacities of circulating angiogenic cells obtained from atherosclerotic patients

Masanori Ohtsuka; Ken-ichiro Sasaki; Takafumi Ueno; Ritsuko Seki; Takaharu Nakayoshi; Hiroshi Koiwaya; Yasuyuki Toyama; Shinji Yokoyama; Yoshiaki Mitsutake; Hidetoshi Chibana; Naoki Itaya; Takashi Okamura; Tsutomu Imaizumi

OBJECTIVE The neovascularization-related capacities of circulating angiogenic cells (CACs) are impaired in atherosclerotic patients, which may explain the unsatisfactory effects of therapeutic angiogenesis with atherosclerotic patient-derived CACs. Platelet-derived microparticles (PMPs) were reported to augment the re-endothelialization capacity of CACs. Accordingly, we investigated whether PMPs could augment the neovascularization-related capacities of atherosclerotic patient-derived CACs in vitro and in vivo and if so, the associated mechanisms. METHODS AND RESULTS We isolated mononuclear cells and PMPs from atherosclerotic patient-derived peripheral blood and generated PMP-pretreated CACs (PMP-CACs) by co-culture of the mononuclear cells and PMPs. Although the migration capacity of PMP-CACs was similar to that of CACs, the adhesion capacity of PMP-CACs was greater. PMPs released RANTES into the culture medium, and the receptors were similarly expressed on the surfaces of CACs and PMP-CACs. Intravenous injection of PMP-CACs to rats with hindlimb ischemia augmented neovascularization of the ischemic limbs more than the injection of CACs. The number of PMP-CACs incorporated into the capillaries of the ischemic limbs was greater than that of incorporated CACs. The augmented adhesion and neovascularization capacities by PMP-CACs were canceled out by a RANTES neutralizing antibody. CONCLUSIONS PMP-secreted RANTES may play a role in the augmenting adhesion and neovascularization capacities of CACs. Injection of PMP-CACs may be a new strategy to augment the effects of therapeutic angiogenesis for limb ischemia in atherosclerotic patients.


Acta Haematologica | 2013

A Case of 8p11 Myeloproliferative Syndrome with BCR-FGFR1 Gene Fusion Presenting with Trilineage Acute Leukemia/Lymphoma, Successfully Treated by Cord Blood Transplantation

Satoshi Morishige; Eijiro Oku; Yuka Takata; Yoshizo Kimura; Fumiko Arakawa; Ritsuko Seki; Rie Imamura; Koichi Osaki; Michitoshi Hashiguchi; Kazuaki Yakushiji; Shin-ichi Mizuno; Koji Yoshimoto; Koji Nagafuji; Koichi Ohshima; Takashi Okamura

The 8p11 myeloproliferative syndrome is a rare neoplasm associated with chromosomal translocations involving the fibroblast growth factor receptor 1 (FGFR1) gene located at chromosome 8p11–12. FGFR1 encodes a transmembrane receptor tyrosine kinase. The resultant fusion proteins are constitutively active tyrosine kinases that drive the proliferation of hematopoietic cells, whose uncontrolled growth can present as a myeloproliferative neoplasm. We report here the case of a 50-year-old man harboring the t(8;22)(p12;q11) chromosomal translocation in cells from both bone marrow and lymph nodes. He presented with acute leukemia and lymphoma with trilineage features. A novel mRNA in-frame fusion between exon 4 of the breakpoint cluster region (BCR) gene at chromosome 22q11 and exon 9 of FGFR1 gene on chromosome 8p11–12 was identified by reverse transcription polymerase chain reaction analysis and was confirmed by DNA sequencing. Because the patient was refractory to chemotherapy, cord blood transplantation was performed in progressive disease. It resulted in a successful outcome in which cytogenetic complete remission has been maintained for 2 years till date.


Therapeutic Apheresis and Dialysis | 2008

Mobilization of bone marrow cells by leukocytapheresis in patients with ulcerative colitis.

Keiichi Mitsuyama; Akira Andoh; Junya Masuda; Hiroshi Yamasaki; Kotaro Kuwaki; Hidetoshi Takedatsu; Ritsuko Seki; Hidemi Nishida; Osamu Tsuruta; Michio Sata

Abstract:  While several trials have suggested that leukocytapheresis by filtration can benefit patients with active ulcerative colitis (UC), mechanisms underlying these benefits are largely unknown. We studied how leukocytapheresis mobilizes bone marrow cells into the peripheral circulation in patients with active UC. Leukocytapheresis transiently reduced peripheral leukocytes, followed by an overshoot increase with emergence of immature leukocytes. The numbers of colonies and CD34+ cells were comparable between UC patients and normal controls. Shortly after leukocytapheresis, the numbers of both colonies and CD34+ cells increased significantly in UC patients (P < 0.0001 and P = 0.0372, respectively). This was not associated with changes in the concentration of circulating cytokines or epinephrine. These results indicate that leukocytapheresis mobilizes bone marrow cells into the circulation. This cell replacement may partly explain the therapeutic benefit in UC. The functional role of the mobilized bone marrow cells in affected intestine remains to be characterized.


Developmental and Comparative Immunology | 2013

Humoral immune responses to CTL epitope peptides from tumor-associated antigens are widely detectable in humans: A new biomarker for overall survival of patients with malignant diseases

Satoko Matsueda; Nobukazu Komatsu; Kenichi Kusumoto; Shintaro Koga; Akira Yamada; Ryoko Kuromatsu; Shingo Yamada; Ritsuko Seki; Shigeru Yutani; Shigeki Shichijo; Takashi Mine; Takaaki Fukuda; Takashi Okamura; Seiya Okuda; Michio Sata; Junichi Honda; Masahide Kaji; Kyogo Itoh; Tetsuro Sasada

Both cellular and humoral immune responses are crucial to induce potent anti-tumor immunity, but most of currently conducted peptide-based cancer vaccines paid attention to cellular responses alone, and none of them are yet approved as a therapeutic modality against cancer patients. We investigated humoral immune responses to CTL epitope peptides derived from tumor-associated antigens in healthy donors and patients with various diseases to facilitate better understanding of their distribution patterns and potential roles. Bead-based multiplex assay, ELISA, and Western blotting were used to measure immunoglobulins reactive to each of 31 different CTL epitope peptides. Importantly, the sums of anti-peptide IgG levels specific to 31 CTL epitope peptides were well correlated with better overall survival (OS) in patients with malignant diseases. Our results suggested that humoral immune responses to CTL epitope peptides were widely detectable in humans. Measurement of immunoglobulins specific to CTL epitope peptides may provide a new biomarker for OS of patients with malignant diseases, although it still remains to be determined whether the correlations between humoral immune responses to epitope peptides and OS are observed only for the CTL epitopes used, or also for other panels of peptides. Quantity of circulating IgG reactive to these peptides was also discussed.


International Journal of Hematology | 2009

Characterization of the light chain-restricted clonal B cells in peripheral blood of HCV-positive patients.

Korenori Ohtsubo; Michio Sata; Takumi Kawaguchi; Satoshi Morishige; Yuka Takata; Eijiro Oku; Rie Imamura; Ritsuko Seki; Michitoshi Hashiguchi; Koichi Osaki; Kazuaki Yakushiji; Taisuke Kanaji; Kohji Yoshimoto; Takato Ueno; Takashi Okamura

To investigate the association between hepatitis C virus (HCV) and B cell proliferation, we searched for the clonal B cells by flow cytometric analysis of the surface immunoglobulin kappa (κ):lambda (λ) light chain ratios of the circulating B (CD19+) cells in 240 HCV-positive patients and 150 negative controls with liver diseases. Clonal B cells with light chain restriction (κ:λ ratio >3:1 or <1:2) were analyzed for CD5 expression and the presence of monoclonal immunoglobulin heavy-chain (IGH) gene rearrangements and the t(14;18) chromosomal translocation. Clonal B cells were detected in 7 cases with HCV (2.9%), but was never detected in the controls (p < 0.05). Of the 7 cases, all had monoclonal IGH gene rearrangements and one had the t(14;18) chromosomal translocation. These HCV-related clonal B cells are not uniform in the intensity of CD5 expression and showed no increase in the frequencies of CD5+ population compared with non-clonal B cells. No “chronic lymphocytic leukemia-phenotype” cells were found. The loss of clonality was observed in 2 cases treated with interferon and in one case treated with splenectomy. The longitudinal study is required to determine whether these circulating clonal B cells progress to lymphoproliferative disorders in future or not.


Bone Marrow Transplantation | 2005

Demonstration of reversed flow in segmental branches of the portal vein with hand-held color Doppler ultrasonography after hematopoietic stem cell transplantation

Michitoshi Hashiguchi; Takashi Okamura; Kohji Yoshimoto; N Ono; Rie Imamura; K Yakushiji; Hisanobu Ogata; Ritsuko Seki; K Otsubo; Eijirou Oku; Mika Kuroiwa; Masakazu Higuchi; Koji Kato; Shuichi Taniguchi; Hisashi Gondo; Tsunefumi Shibuya; Koji Nagafuji; Mine Harada; Michio Sata

Summary:Hepatic veno-occlusive disease (VOD) is a severe complication of hematopoietic stem cell transplantation (SCT). When monitored with hand-held color Doppler ultrasonography during day −7 to +35 around SCT, reversed blood flow in the segmental branches of the portal vein was detected in nine of 56 patients who had undergone SCT. Three of nine patients had clinical evidence of VOD, but six patients did not fulfill the criteria for diagnosis of VOD initially. Two patients progressed to clinical VOD at a later date and the reversed portal flow disappeared with or without treatment for VOD in the other four patients. Monitoring for reversed portal flow with color Doppler ultrasonography may be a useful tool for the early diagnosis of VOD, and may improve prognosis by allowing early initiation of treatment.

Collaboration


Dive into the Ritsuko Seki's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge