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Dive into the research topics where Keiichi Wakabayashi is active.

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Featured researches published by Keiichi Wakabayashi.


Nephrology Dialysis Transplantation | 2014

Paracrine effects of transplanted mesothelial cells isolated from temperature-sensitive SV40 large T antigen gene transgenic rats during peritoneal repair

Reo Kanda; Chieko Hamada; Kayo Kaneko; Takanori Nakano; Keiichi Wakabayashi; Kazuaki Hara; Hiroaki Io; Satoshi Horikoshi; Yasuhiko Tomino

Background The prevention and restoration of peritoneal damage is a critical mission in peritoneal dialysis (PD). Transplantation of mesothelial cells has been suggested to suppress peritoneal injury during PD. Few studies have examined the efficacy and safety of cell transplantation. We evaluated the paracrine effects of mesothelial transplantation during peritoneal repair using immortalized temperature-sensitive mesothelial cells (TSMCs) in chlorhexidine gluconate (CG)-induced peritoneal fibrosis rats. Methods Continuous-infusion pumps containing 8% CG were placed into the abdominal cavity for 21 days. After the removal of the pumps, the TSMCs were injected into the peritoneal cavity at Day 22 (Tx-1 group) or 29 (Tx-2 group). Morphological findings and mRNA expressions of regeneration-related factors were examined at Days 22, 29 and 35. Results Peritoneal thickness was aggravated in the Tx-1 group. Levels of transforming growth factor (TGF)-β, vascular endothelial growth factor (VEGF) and matrix metalloproteinase-2 mRNA in the Tx-1 group at Day 35 were comparable with those at Day 22. The levels of Snail, B-Raf and ERK-1, markers of epithelial to mesenchymal transition and of the RAS/MAPK pathway in the Tx-1 group, were significantly higher than those in the Tx-2 group. TGF-β and VEGF were produced from the transplanted mesothelial cells and the surrounding cells in the Tx-1 group. Conclusion It appears that the paracrine effect of transplanted mesothelial cells during peritoneal repair is associated with its surrounding condition. It is important to determine the most appropriate time for developing peritoneal repair through mesothelial transplantation.


Peritoneal Dialysis International | 2015

Oral Astaxanthin Supplementation Prevents Peritoneal Fibrosis in Rats

Keiichi Wakabayashi; Chieko Hamada; Reo Kanda; Takanori Nakano; Hiroaki Io; Satoshi Horikoshi; Yasuhiko Tomino

♦ Background: Preventing peritoneal damage during peritoneal dialysis is critical. Reactive oxygen species (ROS) have an important role in peritoneal damage; however, few studies have investigated this. We aimed to determine the effects of oral astaxanthin (AST) supplementation in a peritoneal fibrosis (PF) rat model. ♦ Methods: Thirty-seven Sprague–Dawley rats were divided into 5 groups: Control 1 (fed a normal diet without stimulation), Control 2 (fed an AST-supplemented diet without stimulation), Group 1 (fed a normal diet with 8% chlorhexidine gluconate [CG] stimulation for 3 weeks), Group 2 (fed a 0.06% AST-supplemented diet with CG stimulation), and Group 3 (fed a 0.06% AST-supplemented diet that was initiated 4 weeks before CG stimulation). Peritoneal fibrosis, vascular proliferation, and fibrosis-related factor expression were examined. ♦ Results: Peritoneal thickness was significantly suppressed by AST supplementation. Astaxanthin diminished the number of CD68-, 8-hydroxy-2′-deoxyguanosine (8-OHdG)-, and monocyte chemoattractant protein-1 (MCP-1)-positive cells. Type 3 collagen, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and MCP-1 mRNA expression was significantly lower in Group 3 than in Group 1. Increased transforming growth factor-β (TGF-β) and Snail mRNA expression, vascular density, and the number of α-smooth muscle actin (α-SMA)-positive cells were also decreased in Group 3. ♦ Conclusion: Astaxanthin suppressed PF development through the inhibition of inflammation and oxidation in PF rats. It appears that the anti-oxidative agent AST may be useful for the prevention of peritoneal damage.


PLOS ONE | 2017

Scavenging of reactive oxygen species by astaxanthin inhibits epithelial–mesenchymal transition in high glucose-stimulated mesothelial cells

Kazuaki Hara; Chieko Hamada; Keiichi Wakabayashi; Reo Kanda; Kayo Kaneko; Satoshi Horikoshi; Yasuhiko Tomino; Yusuke Suzuki

Background High glucose concentrations influence the functional and structural development of the peritoneal membrane. We previously reported that the oral administration of astaxanthin (AST) suppressed peritoneal fibrosis (PF) as well as inhibited oxidative stress, inflammation, and epithelial–mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) in a chlorhexidine-induced PF rat model. This suggests that oxidative stress induction of EMT is a key event during peritoneal damage. The present study evaluated the therapeutic effect of AST in suppressing EMT, in response to glucose-induced oxidative stress. Methods Temperature-sensitive mesothelial cells (TSMCs) were cultured in the presence or absence of AST and then treated with 140 mM glucose for 3 or 12 hours. Expression levels of TNF-α, TGF-β, and VEGF were determined at the mRNA and protein levels, and nuclear factor kappa B (NF-κB) activity was evaluated. We measured NO2−/NO3− concentrations in cellular supernatants and determined 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels in mitochondrial and nuclear DNA. The expressions of E-cadherin and alpha-smooth muscle actin (α-SMA) were evaluated by double immunofluorescence and protein levels. Results High glucose concentrations induced overproduction of reactive oxidative species (ROS), increasing 8-OHdG mitochondrial DNA and cytokine levels. The NF-κB pathway was activated in response to high glucose concentrations, whereas de novo α-SMA expression was observed with decreased E-cadherin expression. AST treatment attenuated ROS production, inflammatory cytokine production, NF-κB activation, and EMT. Conclusion The findings of the present study indicate that AST may have an anti-EMT effect due to anti-oxidative and anti-inflammatory activities by scavenging glucose-induced ROS from mitochondria in PMCs. AST may be an efficacious treatment for PF.


Seminars in Dialysis | 2014

Comparison Between the Fixation of Peritoneal Dialysis Catheters to the Peritoneal Wall and the Conventional Placement Technique: Clinical Experience and Follow-Up of a New Implant Technique for Peritoneal Dialysis Catheters

Hiroaki Io; Kunimi Maeda; Yoshimi Sekiguchi; Tetsutaro Shimaoka; Seiki Aruga; Junichiro Nakata; Hirotaka Nakamoto; Yoko Hotta; Ichiro Koyanagi; Masanori Inaba; Reo Kanda; Takanori Nakano; Keiichi Wakabayashi; Yuu Sasaki; Jiro Inuma; Kayo Kaneko; Chieko Hamada; Mitsumine Fukui; Yasuhiko Tomino

Peritoneal dialysis (PD) catheters often become severely dislocated, which may lead to malfunction. With the aim of preventing this complication, we have developed a simple method of fixing the catheter downwards in the peritoneal cavity (fixation technique), a technique that does not require a laparoscope. Sixteen patients were implanted using the conventional placement technique and 25 patients were implanted using the fixation technique. The location of the catheter tip was classified from grade 1 (downward, normal) to 5 (dislocated). The frequency of dislocation (defined as the extended time and/or decrease in volume when draining the PD solution) was measured for both the fixation technique and conventional placement technique. There was a significant difference in grade between the fixation technique (2.72 ± 1.01) and conventional technique (3.92 ± 1.31). The time until first dislocation was significantly different between the fixation technique (59.3 ± 48.1 days) and conventional technique (8.8 ± 14.6 days). The time until any dislocation was significantly different between the fixation technique (69.2 ± 41.9 days) and conventional technique (12.9 ± 13.7 days). Complications were not significantly different between the fixation technique and conventional technique. The fixation technique appears to be simple, safe, and useful for preventing severe dislocation and for lengthening the time until dislocation in PD patients.


Therapeutic Apheresis and Dialysis | 2017

Evaluation of Long-Term Combination Therapy With Peritoneal Dialysis and Hemodialysis

Reo Kanda; Hiroaki Io; Junichiro Nakata; Yuko Makita; Yu Sasaki; Mayumi Matsumoto; Keiichi Wakabayashi; Yasuhiko Tomino; Yusuke Suzuki

It is well known that a combination therapy with peritoneal dialysis (PD) and hemodialysis (HD) is feasible and may improve clinical status in patients for whom adequate solute and fluid removal is difficult to achieve with PD alone. The objective of the present study was to evaluate whether the therapy is useful in the likelihood of long‐term peritoneal membrane and cardiac function. The therapy was 6 days of PD and one session of HD per week. Physical, biochemical, dialysate‐to‐plasma ratio of creatinine (D/P Cr), arteriovenous fistula (AVF) blood flow, and left ventricular mass index (LVMI) data were prospectively analyzed in 30 patients with measurements performed at 0 and 6 months, and for 21 patients, 12 or 18 months after initiation of the therapy. The levels of hemoglobin (Hb) after therapy were significantly higher than those at the initiation of therapy. The levels of LVMI and human atrial natriuretic peptide (hANP) after therapy were significantly lower than those at the initiation of therapy, whereas AVF blood flow did not change significantly. D/P Cr levels at 6 months after the therapy were significantly lower than those at the initiation of therapy. D/P Cr levels at 12 or 18 months after the therapy were not aggravated. It appears that the therapy improves Hb levels and cardiac function because of adjusting body fluid status. It was indicated that peritoneal function after therapy may be improved. Therefore, combination therapy is useful from the lifestyle viewpoint of patients in the transition period of PD to HD with end‐stage kidney disease.


Blood Purification | 2017

Effects of Cardiac Function with Postoperative Arteriovenous Fistula Blood Flow in Patients with Hemodialysis

Keiichi Wakabayashi; Hiroaki Io; Junichiro Nakata; Hirotaka Nakamoto; Michiko Sato; Yu Sasaki; Yoshio Shimizu; Satoshi Horikoshi; Yasuhiko Tomino; Yusuke Suzuki

Background/Aims: This study was aimed at evaluating the effect of cardiac function with postoperative arteriovenous fistula (AVF) blood flow in hemodialysis (HD) patients. Methods: A total of 45 HD patients were examined at the Juntendo University Hospital. The AVF blood flow was measured using ultrasonography, and the cardiac function was measured using echocardiography. Correlation between these parameters and the rate of change in body weight (BW) was analyzed. Results: The number of postoperative days significantly correlated with the AVF blood flow, and it positively correlated with the stroke volume (SV). The postoperative AVF blood flow in patients with reduced ejection fraction (EF) was lower than that in patients with normal EF. The rate of change of BW negatively correlated with that of SV, positively correlated with cardiac output (CO), and positively correlated with CO in patients with an AVF blood flow of more than 1,000 mL/min. Conclusion: It appears that the cardiac function can be improved by controlling the BW even in patients with high AVF blood flow.


Journal of Nephrology | 2014

Adipose-derived mesenchymal stem cells transplantation facilitate experimental peritoneal fibrosis repair by suppressing epithelial-mesenchymal transition

Keiichi Wakabayashi; Chieko Hamada; Reo Kanda; Takanori Nakano; Hiroaki Io; Satoshi Horikoshi; Yasuhiko Tomino


Journal of Artificial Organs | 2013

Pentraxin 3 as a new biomarker of peritoneal injury in peritoneal dialysis patients

Reo Kanda; Chieko Hamada; Kayo Kaneko; Takanori Nakano; Keiichi Wakabayashi; Hiroaki Io; Satoshi Horikoshi; Yasuhiko Tomino


Clinical Nephrology | 2014

Hyaline vascular type of unicentric Castleman's disease with proliferation of glomerular endothelial cells.

Keiichi Wakabayashi; Katsuhiko Asanuma; Yukihiko Takeda; Atsushi Arakawa; Isao Osawa; Satoshi Horikoshi; Takashi Yao; Yasuhiko Tomino


Nephrology Dialysis Transplantation | 2016

SP459IMPACT OF OXIDATIVE STRESS ON EPITHELIAL MESENCHYMAL TRANSITION IN MESOTHELIAL CELLS ISOLATED FROM TEMPERATURE-SENSITIVE SV40 LARGE T-ANTIGEN GENE TRANSGENIC RATS

Kazuaki Hara; Chieko Hamada; Keiichi Wakabayashi; Reo Kanda; Hiroaki Io; Satoshi Horikoshi

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