Network


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

Hotspot


Dive into the research topics where Yukihiko Nakamura is active.

Publication


Featured researches published by Yukihiko Nakamura.


Stroke | 2016

Leakage Sign for Primary Intracerebral Hemorrhage A Novel Predictor of Hematoma Growth

Kimihiko Orito; Masaru Hirohata; Yukihiko Nakamura; Nobuyuki Takeshige; Takachika Aoki; Gousuke Hattori; Kiyohiko Sakata; Toshi Abe; Yuusuke Uchiyama; Teruo Sakamoto; Motohiro Morioka

Background and Purpose— Recent studies of intracerebral hemorrhage treatments have highlighted the need to identify reliable predictors of hematoma expansion. Several studies have suggested that the spot sign on computed tomographic angiography (CTA) is a sensitive radiological predictor of hematoma expansion in the acute phase. However, the spot sign has low sensitivity for hematoma expansion. In this study, we evaluated the usefulness of a novel predictive method, called the leakage sign. Methods— We performed CTA for 80 consecutive patients presenting with spontaneous intracerebral hemorrhage. Two scans were completed: CTA phase and delayed phase (5 minutes after the CTA phase). By comparing the CTA phase images, we set a region of interest with a 10-mm diameter and calculated the Hounsfield units. We defined a positive leakage sign as a >10% increase in Hounsfield units in the region of interest. Additionally, hematoma expansion was determined on plain computed tomography at 24 hours in patients who did not undergo emergent surgery. Results— Positive spot signs and leakage signs were present in 18 (22%) patients and 35 (43%) patients, respectively. The leakage sign had higher sensitivity (93.3%) and specificity (88.9%) for hematoma expansion than the spot sign. The leakage sign, but not the spot sign, was significantly related with poor outcomes (severely disabled, vegetative state, and death) in all of the patients (P=0.03) and in patients with a hemorrhage in the putamen (P=0.0016). Conclusions— The results indicate that the leakage sign is a useful and sensitive method to predict hematoma expansion.


American Journal of Clinical Pathology | 2012

Clinicopathologic analysis of peripheral T-cell lymphoma, follicular variant, and comparison with angioimmunoblastic T-cell lymphoma: Bcl-6 expression might affect progression between these disorders.

Hiroaki Miyoshi; Kensaku Sato; Daisuke Niino; Fumiko Arakawa; Yoshizo Kimura; Junichi Kiyasu; Masanori Takeuchi; Maki Yoshida; Yosuke Okada; Yukihiko Nakamura; Yasuo Sugita; Koichi Ohshima

We examined clinicopathologic findings in 17 cases of peripheral T-cell lymphoma, follicular variant (f-PTCL), and compared these findings with angioimmunoblastic T-cell lymphoma (AITL) to determine whether they were identical to the spectrum of changes seen in AITL and how each of the findings in f-PTCL were related to the characteristics of AITL. Almost all f-PTCL cases showed pathologic characteristics of AITL and immunohistochemical positivities in lymphoma cells for CD4, CD10, Bcl-6, PD-1, and CXCL13. Except for pathologic characteristics, clinicopathologic findings in f-PTCL had few significant differences from AITL. The positive rate for Bcl-6 expression in neoplastic cells was significantly associated with the frequency of polymorphic infiltrates, vascular proliferation, B-immunoblasts, clear cells, Epstein-Barr virus-positive lymphocytes, hepatosplenomegaly, and skin rash. Our study confirmed the continuity between f-PTCL and AITL. Moreover, Bcl-6 expression in f-PTCL was statistically associated with the characteristics of AITL.


Cancer Science | 2012

Comparison of CD20 expression in B-cell lymphoma between newly diagnosed, untreated cases and those after rituximab treatment

Hiroaki Miyoshi; Fumiko Arakawa; Kensaku Sato; Yoshizo Kimura; Junichi Kiyasu; Masanori Takeuchi; Maki Yoshida; Ayako Ichikawa; Yukinao Ishibashi; Yukihiko Nakamura; Shinji Nakashima; Daisuke Niino; Yasuo Sugita; Koichi Ohshima

Few studies have statistically investigated reduced CD20 expression in B‐cell lymphoma after rituximab therapy and genomic mutation of CD20 associated with reduction. We examined CD20‐positive rate in follicular lymphoma (FL) and diffuse large B‐cell lymphoma (DLBCL) by flow cytometry (FCM) and immunohistochemical staining (IHS), comparing 138 cases after rituximab therapy with 360 initial, not yet treated cases. Sequence analysis of exons 3 to 8 of CD20 was performed on 22 cases with low CD20‐positive rate after rituximab treatment. The results showed a statistical correlation between CD20‐positive rate in FCM and IHS. By FCM, the CD20‐positive rate among post‐rituximab cases was significantly lower than among initial cases in DLBCL, non‐germinal center origin B‐cell type (average values [avg] 57.8 and 87.9, respectively) (P < 0.0001), FL2 (avg, 93.9; 103.2) (P = 0.0083), and FL3A (avg, 90.6; 100.7) (P = 0.033). Stratified analyses of post‐rituximab cases showed significantly lower CD20‐positive rate in cases that were resistant at the start of the treatment and cases with progressive disease during rituximab therapy before biopsy. Sequence analysis showed silent mutation of exon 4 (632 C/T) in seven cases, although this number was not statistically significant. These results suggest the influence of B‐lymphoma subtype and a therapeutic effect before biopsy on CD20 expression at relapse and contribute to a better therapeutic approach for relapse cases after rituximab therapy. (Cancer Sci, doi: 10.1111/j.1349‐7006.2012.02307.x, 2012)


Pathology International | 2012

Epstein-Barr virus-positive lymphoproliferative disorder associated with old organized chronic subdural hematoma

Yasuo Sugita; Masaru Ohta; Koichi Ohshima; Daisuke Niino; Yukihiko Nakamura; Yosuke Okada; Shinji Nakashima

This report describes a case of an immunocompetent 77‐year‐old male with Epstein‐Barr virus (EBV)‐positive lymphoproliferative disorder associated with calcified chronic subdural hematoma (CSH). On the day prior to consultation in our outpatient clinic, the patient fell from his bed, striking his frontal head on the floor. Magnetic resonance imaging showed ill‐defined lesions in the right frontal‐temporal subdural regions. At surgery, a hard and thickened outer membrane of a CSH and muddy organized subdural hematoma were observed. However, macroscopic neoplastic lesions were not apparent. Histologically, there were atypical lymphoid cells scattered or conglomerated in some areas of the thick outer membrane of the CSH. They were composed of occasional large atypical lymphoid cells. The lesions were accompanied by necrosis. Atypical lymphoid cells were immunopositive for B‐cell markers but not for T‐cell markers. EBNA2 was seen in the nuclei of tumor cells. Atypical lymphoid cells showed positive signals for EBV‐encoded small RNAs (EBERs) on in situ hybridization. These findings were consistent with EBV‐positive lymphoproliferative disorder associated with CSH. These results also suggested that EBV and the inflammatory reaction found in the CSH could be the etiological factors in the pathogenesis of lymphoproliferative disorder.


Pathology International | 2014

CD5-positive follicular lymphoma characterized by CD25, MUM1, low frequency of t(14;18) and poor prognosis

Hiroaki Miyoshi; Kensaku Sato; Maki Yoshida; Yoshizo Kimura; Junichi Kiyasu; Ayako Ichikawa; Yukinao Ishibashi; Fumiko Arakawa; Yukihiko Nakamura; Shinji Nakashima; Daisuke Niino; Yasuo Sugita; Koichi Ohshima

CD5‐positive follicular lymphoma (FL), although rare, has been described in a number of case reports. However, a statistically valid, clinicopathological comparison between CD5‐positive FL and CD5‐negative FL has never been performed because of its rarity. We statistically compared clinicopathological characteristics of 22 cases of CD5‐positive FL, diagnosed by immunohistochemistry, flow cytometry and morphological findings, with those of 62 cases of FL without CD5 expression (control cases). CD5‐positive FL patients showed a higher tendency of peripheral blood involvement (P = 0.076) and a higher frequency of CD25 expression (P = 0.0004) and MUM1 protein expression (P = 0.0008), and a lower frequency of t(14;18)(q32;q21) (P = 0.017). The overall survival (OS) curve of CD5‐positive FL was significantly worse than that of control cases (P = 0.0266), although progression‐free survival curves did not show a significant difference (P = 0.7899). Moreover, CD5 expression was shown to be an independent poor prognostic factor for OS in both univariate analysis [Hazard Ratio (HR), 3.63; P = 0.0464] and multivariate analysis (HR, 57.16; P = 0.0001). CD5‐positive FL showed different clinicopathological characteristics from FL lacking CD5 expression. These results suggest that CD5‐positive FL should be considered a different type of FL, and its clinicopathological management should be conducted differently.


Journal of Stroke & Cerebrovascular Diseases | 2016

Alternatively Activated Macrophages Play an Important Role in Vascular Remodeling and Hemorrhaging in Patients with Brain Arteriovenous Malformation.

Yukihiko Nakamura; Yasuo Sugita; Shinji Nakashima; Yousuke Okada; Munetake Yoshitomi; Yoshizou Kimura; Hiroaki Miyoshi; Motohiro Morioka; Koichi Ohshima

BACKGROUND Angiogenic and immunoactive lesions in brain arteriovenous malformation (BAVM) contribute to hemorrhagic events and the growth of BAVMs. However, the detailed mechanism is unclear. Our objective is to clarify the relationship between hemorrhagic events of BAVM and alternatively activated macrophages in the perinidal dilated capillary network (PDCN). METHODS We examined microsurgical specimens of BVMs (n = 29) and focused on the PDCN area. Ten autopsied brains without intracranial disease were the controls. We performed immunostaining of the inflammatory and endothelial cell markers, macrophage markers (CD163 and CD68), and vascular endothelial growth factor A (VEGF-A). We evaluated each cells density and the vessel density in the PDCN and analyzed the relationship to hemorrhagic events of BAVM. RESULTS The PDCN was involved in all the resected arteriovenous malformations, and these vessels showed a high rate of CD105 expression (72.0 ± 10.64%), indicating newly proliferating vessels. Alternatively activated macrophages were found, with a high rate (85.6%) for all macrophages (controls, 56.6%). In the hemorrhagic cases, the cell density was significantly higher than that in the nonhemorrhagic cases and controls (hemorrhagic group, 290 ± 44 cells/mm(2); nonhemorrhagic group, 180 ± 59 cells/mm(2); and control, 19 ± 8 cells/mm(2)). The cell density of alternatively activated macrophages showed a positive correlation with the vessel density of the PDCN. Double immunostaining showed that VEGF-A was secreted by alternatively activated macrophages. CONCLUSION Our data suggest that alternatively activated macrophages may have some relationships with angiogenesis of PDCN and hemorrhagic event of BAVM.


Jacc-cardiovascular Imaging | 2015

Noninvasive evaluation of bone-forming activity within the calcified atherosclerotic lesions by Tc 99m HMDP scintigraphy.

Nobuhiro Tahara; Atsuko Tahara; Akihiro Honda; Yoshikazu Nitta; Sachiyo Igata; Yukihiko Nakamura; Yasuharu Takeuchi; Hidetoshi Akashi; Hiroyuki Tanaka; Motohiro Morioka; Jagat Narula; Sho-ichi Yamagishi; Yoshihiro Fukumoto

The process of active calcium deposition as demonstrated by radiolabeled fluoride uptake has been recently proposed to be associated with high-risk plaques [(1)][1]. Similarly, the computed tomography (CT)-verified spotty calcification is associated with the plaques that have resulted in recent


Neuropathology | 2014

Ependymosarcoma with eosinophilic granular cells

Yasuo Sugita; Mizuhiko Terasaki; Motohiro Morioka; Shinji Nakashima; Yukihiko Nakamura; Koichi Ohshima

Ependymosarcoma is a new entity of malignant gliomas composed of ependymal and sarcomatous components. We report a rare case of ependymosarcoma with eosinophlic cells which occurred to the right trigon of the lateral ventricle. A 62‐year‐old man complained of headaches over a 2‐month period. A hard, gray mass was found in the right trigon of the lateral ventricle during the operation. Although he received radiation and chemotherapy, the patient died due to tumor disseminating through the whole brain within 7 months after the operation. The histological examination revealed that the anaplastic glial components intermingled with the sarcomatous components. Immunohistochemically, sarcomatous cells were positive for α smooth muscle actin and desmin. However, anaplastic glial cells were not positive for these markers. In addition, Masson trichrome stain showed a plethora of collagen fibers between sarcomatous cells, but no collagen fibers were produced by the glial tumor cells. Solid focal papillary lesions of the glial tumor showed dot‐like epithelial membrane antigen and diffuse cytoplasmic D2‐40 immunoreactivity. Based on the above findings, these anaplastic glial tumor cells should show focal ependymal differentiation, and sarcomatous cells show myofibroblastic differentiation. In addition, almost 10% of the tumor cells in the neoplasm showed bright eosinophilic granules in the cytoplasm. These cytoplasmic eosinophilic granules and bundles were negative on PAS staining. Intracytoplasmic eosinophilic granules of tumor cells were strongly positive for αB‐crystallin, HSP 27 and GFAP, respectively. These findings suggest that the clinicopathological characteristics of the present case should be consistent with the criterion of ependymosarcoma by Rodriguez et al.


Neuropathology | 2013

Recurrent left frontal lobe cystic tumor in a 49‐year‐old woman

Yasuo Sugita; Shinji Nakashima; Yukihiko Nakamura; Koichi Ohshima; Mizuhiko Terasaki; Hikaru Maruiwa

A 49-year-old woman presented with a chief complaint of a headache of 1 month’s duration. MRI revealed a ringenhanced cyst with a plaque-like mass in the left frontal lobe (Fig. 1). Surgical exposure revealed an elastic, soft, yellow, plaque-like mass in the left frontal lobe, which by gross criteria was removed successfully. The patient’s postoperative course was uneventful. However, 9 months after surgery, the patient again complained of a headache; an MRI revealed an irregular, enhanced polycystic mass in the left frontal lobe. Macroscopic findings during the second surgical procedure revealed a polycystic tumor infiltrating into surrounding normal brain tissue. Subtotal tumor removal was performed. Postoperatively, the patient received adjuvant temozolomide and radiotherapy. After 2 years of follow-up sessions subsequent to the second procedure, the patient remains well with no tumor recurrence seen on MRI.


Pathology International | 2011

Case of polycythemia vera with unusual organizing pneumonia mimicking the clinical features of military tuberculosis and possibly caused by the involvement of neoplastic megakaryocytes

Yoshizo Kimura; Yutaka Imamura; Koichi Higaki; Yuju Ohno; Namiko Hashiguchi; Rituko Seki; Takashi Okamura; Fumiko Arakawa; Junichi Kiyasu; Masanori Takeuchi; Hiroaki Miyoshi; Maki Yoshida; Yukihiko Nakamura; Daisuke Niino; Yasuo Sugita; Koichi Ohshima

Polycythemia vera (PV) is a clonal myeloproliferative neoplasm (MPN) of hematopoietic stem cells. Although the management of MPN patients generally focuses on the prevention of thromboembolic events caused by hypercoagulability, it is true that the patients with hematological malignancy often suffer from pulmonary diseases with atypical radiological patterns. We present here a 56‐year‐old woman with PV harboring a JAK2V617F mutation that had a diffuse reticulonodular pattern on chest radiography and was initially suspected of having military tuberculosis. Pathological assessment of a video‐assisted thoracoscopic surgery lung biopsy revealed that the lesions were in fact organizing pneumonia (OP). Interestingly, pulmonary extramedullary hematopoiesis with a diffuse plugging of the alveolar blood capillaries by numerous atypical megakaryocytes was also observed around the granulation components. The histological findings of our case of unusual OP suggest that local activated neoplastic megakaryocytes and platelets played an important role in the development of spreading fibrotic lesions. JAK2 mutation or the preleukemic phase of MPN may accelerate the activation of megakaryocytes and result in the proliferative process of fibrosis.

Collaboration


Dive into the Yukihiko Nakamura'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