Are you Takanori Oyama?

Claim your profile

Publications (7)6.67 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The limited application of small bowel transplantation for short bowel syndrome, mainly on the account of the morbidity and long-term implications of the procedure, has led to a search for alternative therapies. The purpose of this study was to evaluate whether basic fibroblast growth factor (bFGF) could facilitate regeneration of fetal small intestinal mucosa in vivo. Intestinal epithelial organoid units harvested from fetal Lewis rats were injected into adult male Lewis rats whose colon was denuded of mucosa, as syngeneic recipients. One experimental group transplanted with the addition of 50 ng/ml bFGF, was compared with a control group that were transplanted without bFGF. The grafts were harvested and analyzed using histology and immunohistochemistry 3 weeks after operation. There were 4 anesthetic deaths, two in each group, and 11 deaths due to adhesive ileus. In no rat did neomucosa fully cover the denuded colonic muscle throughout the whole length of lumen. Histologically, the structure of the neomucosa, when present, was normal small intestinal mucosa. The small intestinal mucosa was partially restored in 100% (6 of 6) of bFGF, and in 28.6% (2 of 7) of those not given bFGF (P = 0.0021). These data demonstrate that bFGF can facilitate the restoration of intestinal epithelial cells, at least to some degree. Potentially, refinements of this technique could be used to facilitate the physiologic tissue engineering of small intestine in a way that allows it to move peristaltically, and have an application in the management of patients with short bowel syndrome.
    Pediatric Surgery International 07/2009; 25(8):691-5. · 1.22 Impact Factor
  • Nihon Rinsho Geka Gakkai Zasshi (Journal of Japan Surgical Association) 01/2007; 68(5):1070-1076.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The mechanisms whereby grafts in the recipients can be primed for regeneration following living donor liver transplantation (LDLT) are poorly understood. The present study was designed to understand the mechanism for posttransplant regeneration in small-for-size liver graft. Out of LDLT cases, we examined patients with end-stage liver cirrhosis and subsequent transplantation. A total of 16 patients were divided into 2 groups, group L (large graft) and group S (small graft). We examined the serum biochemical markers and cytokines preoperatively and postoperatively. We also carried out hemodynamic analysis by measuring the portal and arterial peak velocity. The differences in ages, preoperative biochemical markers and MELD score between the two groups were not statistically significant. Though differences in the preoperative levels of IL-6, sIL-6R and HGF were not significant between the two groups, IL-6 and HGF levels in group S significantly increased postoperatively. Immediate and significant increase of Vp max was also observed in group S. Two weeks after LDLT, the regeneration rate in group S was significantly higher than that in group L. These findings may allow us to speculate that immediate increase of portal pressure, reflecting sinusoidal tensile/shear stress, accelerates liver regeneration through immediate induction of IL-6 and HGF.
    Hepato-gastroenterology 01/2007; 54(79):2078-83. · 0.77 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Previous studies have shown small intestinal submucosa (SIS) can be used as biodegradable scaffolds in tissue engineering small intestine. The purpose of this study is to evaluate the regeneration of neointestine and its morphology using SIS. A 2-cm tubular SIS graft from Sprague Dawley rat donors was interposed in the middle of a 6-cm ileal Thiry-Vella loop of Lewis rats, which was used to construct an ileostomy. The grafts were harvested at each of the time points ranging from 2 weeks to half a year after implantation, and native small intestine and grafts were investigated for morphology using histology and immunohistochemistry. At the early postoperative period, SIS grafts were colonized by numerous inflammatory cells. A mucosal epithelial layer began to line the luminal surface of the graft by 4 weeks, and by 12 weeks, the luminal surface was covered completely by a layer of neomucosa. Neomucosa with typical small bowel morphology was characterized by a columnar epithelial cell layer with goblet cells, Paneth cells, absorptive enterocytes, and enteroendocrine cells. Significant differences between neomucosa by 12 weeks and 24 weeks in the measurements of mucosal thickness, villus height, and crypt depth were found. The outer walls of SIS grafts were composed of distinct bundles of well-formed smooth muscle-like cells with some fibrovascular tissue. This initial study suggests that tissue engineering neointestine using SIS can develop structural features of the normal intestine. Small intestinal submucosa might be a viable material in the creation of neointestine for patients suffering short bowel syndrome.
    Journal of Pediatric Surgery 01/2006; 40(12):1898-902. · 1.38 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Donor-specific immunosuppression is important in transplant surgery. We examined the effect of intraportal donor-specific bone marrow transplantation on heterotopic small bowel transplantation in the high responder rat combination, ACI to Lewis. The study comprised five treatment groups: untreated controls (group 1); FK506 alone (group 2); low-dose predonine + FK506 (group 3); high-dose predonine + FK506 (group 4); and intraportal donor-specific bone marrow transplantation + FK506 (group 5). Intraportal transplantation was performed pre-operatively and FK506 and predonine given post-operatively. Intestinal allograft survival and changes of intragraft cytokine expression were analysed using the reverse transcription polymerase chain reaction. Allograft survival (mean +/- SD) was lowest in group 1 and greatest in group 5. The group 5 treatment regimen also down-regulated interferon-gamma and interleukin-2 transcription in the transplanted intestine. Intraportal donor bone marrow transplant combined with FK506 immunosuppression was found therefore to be the most beneficial treatment regimen.
    The Journal of international medical research 08/2003; 31(4):281-9. · 0.96 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the immune responses of patients with cholestatic and hepatitis C virus-positive (HCV-positive) liver cirrhosis by analysing T-cell subsets and cytokine levels in the portal and peripheral veins, using flow cytometry and enzyme-linked immunosorbent assay. In cholestatic liver cirrhosis, the proportion of natural-killer (NK) T cells and interleukin (IL) 6 and IL-18 levels in the portal venous blood were significantly higher than those in the peripheral venous blood. In HCV-positive liver cirrhosis, the proportions of NK T cells and Fas+ T cells and IL-6 and soluble Fas levels in the portal venous blood were significantly higher than those in the peripheral venous blood. These results suggest that in these diseases, activated T cells and soluble molecules in portal venous blood may promote Fas/FasL-mediated apoptosis of the bile-duct cells and hepatocytes, and contribute to the deterioration in liver function as an inevitable result of positive feedback.
    The Journal of international medical research 06/2003; 31(3):170-80. · 0.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The authors experienced an extremely rare case of secondary sclerosing cholangitis and portal hypertension developed as late complications of hemolytic uremic syndrome (HUS) owing to Escherichia coli O157:H7 in a 2-year-old boy. HUS after E coli O157 infection is the most frequent cause of acute renal failure in childhood and occasionally is accompanied by extrarenal complications such as encephalopathy, cardiomyopathy, ischemic colitis, and pancreatitis. Rarely, late colonic stenosis may develop secondary to the ischemic damage. Sclerosing cholangitis and subsequent cirrhosis with portal hypertension are very uncommon as late complications of HUS. To our knowledge, such a case has not been previously reported in the literature. J Pediatr Surg 36:1838-1840.
    Journal of Pediatric Surgery 01/2002; 36(12):1838-40. · 1.38 Impact Factor