Tomoharu Miyashita

Tomoharu Miyashita

orcid

Research Focus & Metrics

Academic Career Length

28Years (1999-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 2015 in Journal of Surgical Research
Verified
Journal Article
Closed access
TMTomoharu Miyashita
Tomoharu Miyashita
HTHidehiro Tajima
Hidehiro Tajima
IMIsamu Makino
Isamu Makino
HNHisatoshi Nakagawara
Hisatoshi Nakagawara
HKHirohisa Kitagawa
Hirohisa Kitagawa
TOTetsuo Ohta
Tetsuo Ohta

14 October 2015 in European Surgery
Verified
Journal Article
Open access
PDF file
TMTomoharu Miyashita
Tomoharu Miyashita
SNShinichi Nakanuma
Shinichi Nakanuma
AAA.K. Ahmed
A.K. Ahmed
IMI. Makino
I. Makino
HHH. Hayashi
H. Hayashi
TOT. Ohta
T. Ohta
Summary: Background: The exact sequence of events leading to ultimate hepatocellular damage following ischemia/reperfusion (I/R) is incompletely understood. In this article, we review a mechanism of organ dysfunction after hepatic I/R or immunosuppressive treatment, in addition to the potential of liver sinusoidal endothelial cell (LSEC) protection and antiplatelet treatment for the suppression of hepatocellular damage.Methods: A review of the literature, utilizing PubMed-NCBI, was used to provide information on the components necessary for the development of hepatocellular damage following I/R.Results: It is well-established that LSECs damage following hepatic I/R or immunosuppressive treatment followed by extravasated platelet aggregation (EPA) is the root cause of organ dysfunction in liver transplantation. We have classified three phases, from LSECs damage to organ dysfunction, utilizing the predicted pathogenic mechanism of sinusoidal obstruction syndrome. The first phase is detachment of LSECs and sinusoidal wall destruction after LSECs injury by hepatic I/R or immunosuppressive treatment. The second phase is EPA, accomplished by sinusoidal wall destruction. The various growth factors, including thromboxane A2, serotonin, transforming growth factor-beta and plasminogen activator inhibitor-1, released by EPA in the Disse’s space of zone three, induce portal hypertension and the progression of hepatic fibrosis. The third phase is organ dysfunction following portal hypertension, hepatic fibrosis, and suppressed liver regeneration through various growth factors secreted by EPA.Conclusion: We suggest that EPA in the space of Disse, initiated by LSECs damage due to hepatic I/R or immunosuppressive treatment, and activated platelets may primarily contribute to liver damage in liver transplantation. Endothelial protective therapy or antiplatelet treatment may be useful in the treatment of hepatic I/R following EPA.

5 November 2017 in In Vivo
Verified
Journal Article
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KSKentaro Sakurai
Kentaro Sakurai
TMTomoharu Miyashita
Tomoharu Miyashita
MOMitsuyoshi Okazaki
Mitsuyoshi Okazaki
TYTakahisa Yamaguchi
Takahisa Yamaguchi
YOYoshinao Ohbatake
Yoshinao Ohbatake
TOTetsuo Ohta
Tetsuo Ohta
Background/Aim: Severe sepsis is associated with high morbidity and mortality rates. Inflammation and coagulation play pivotal roles in the pathogenesis of sepsis leading to multiple organ failure, especially in the liver. The aim of the present study was to assess the mechanism from sepsis to liver damage in a mouse model. Materials and Methods: We created a sepsis model by injecting lipopolysaccharide (LPS) intraperitoneally in mice. At 0, 6, 12, and 24 h following intraperitoneal injection of LPS, mice were euthanised and analyzed. Primary antibodies against myeloperoxidase (MPO), hepatic sinusoidal endothelial cells (SE-1), and P-selectin (CD62p) were used. Expression and localization in neutrophil, sinusoidal endothelial, and platelet cells were assessed by immunohistochemistry. Results: Immunohistochemical analyses revealed a positive staining for MPO, most abundantly in neutrophil granulocytes, within the hepatic sinusoids immediately after injection. Neutrophil extracellular trap (NET)-like structures stained for MPO, indicating the presence of neutrophils undergoing NETosis, were confirmed at 6 h after LPS administration. SE-1 staining for liver sinusoidal endothelial cells was significantly reduced at 12 h post-LPS administration through sinusoidal endothelial injury or detachment. Furthermore, the presence of extravasated platelets was confirmed in the space of Disse at 24 h after LPS administration. Blood sample analyses showed that white blood cell counts and platelet counts decreased gradually, while MPO amounts increased until 12 h after LPS administration. Conclusion: We conclude that NET formation and intravasated platelet aggregation are the first steps from sepsis to liver damage, and that extravasated platelet aggregation promoted by NET-facilitated detachment of sinusoidal endothelial cells is the origin of sepsis-induced liver dysfunction.

1 February 2019 in Journal of Surgical Research
Verified
Journal Article
Closed access
KNKozo Nomura
Kozo Nomura
TMTomoharu Miyashita
Tomoharu Miyashita
YYYasuhiko Yamamoto
Yasuhiko Yamamoto
SMSeiichi Munesue
Seiichi Munesue
AHAi Harashima
Ai Harashima
TOTetsuo Ohta
Tetsuo Ohta

14 February 2014 in Annals of Surgical Oncology
Verified
Journal Article
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TMTomoharu Miyashita
Tomoharu Miyashita
HTHidehiro Tajima
Hidehiro Tajima
FSFurhawn A. Shah
Furhawn A. Shah
MOMasanobu Oshima
Masanobu Oshima
IMIsamu Makino
Isamu Makino
TOTetsuo Ohta
Tetsuo Ohta

2 January 2018 in Anticancer Research
Verified
Journal Article
Open access
PDF file
TMTomoharu Miyashita
Tomoharu Miyashita
HTHidehiro Tajima
Hidehiro Tajima
IMIsamu Makino
Isamu Makino
MOMitsuyoshi Okazaki
Mitsuyoshi Okazaki
TYTakahisa Yamaguchi
Takahisa Yamaguchi
TOTetsuo Ohta
Tetsuo Ohta
Background: In this study, the effects of neoadjuvant chemotherapy (NAC) on cancer-associated fibroblasts (CAFs) in pancreatic cancer stroma were investigated. Materials and Methods: Density of α-smooth muscle actin (αSMA)-positive fibroblasts in resected surgical specimens from untreated patients, patients receiving conventional gemcitabine plus S-1 (GS), and patients receiving gemcitabine plus nab-paclitaxel (GnP) was determined by hybrid cell counting. 18F-Fluorodeoxyglucose positron-emission tomography (FDG-PET) scans and carbohydrate antigen 19-9 (CA19-9) concentrations were used to assess tumor activity before and after chemotherapy in the GnP group. Results: In this retrospective study of 65 patients, αSMA expression was reduced in the GnP group, as revealed by markedly disorganized collagen and a low density of αSMA-positive fibroblasts. There were significantly fewer αSMA-positive fibroblasts in the GnP than in the untreated and GS groups, but there was no significant difference between the latter two groups. αSMA density reflected a decrease in standardized uptake value on FDG-PET, but not CA19-9 concentration, after GnP chemotherapy. Conclusion: These data suggest that the GnP regimen induces stromal depletion, resulting in fewer CAFs.