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Featured researches published by Youichi Kawano.


The American Journal of Gastroenterology | 2005

Long-Term Results of Partial Splenic Artery Embolization as Supplemental Treatment for Portal-Systemic Encephalopathy

Hiroshi Yoshida; Yasuhiro Mamada; Nobuhiko Taniai; Kazuhito Yamamoto; Masahiro Kaneko; Youichi Kawano; Yoshiaki Mizuguchi; Tatsuo Kumazaki; Takashi Tajiri

OBJECTIVES:To present long-term results of angiographic partial splenic artery embolization (PSE) as a supplemental treatment of portal-systemic encephalopathy.METHODS:Twenty-five patients with portal-systemic encephalopathy were divided into two groups: 14 patients underwent transportal obliteration and/or balloon-occluded retrograde transvenous obliteration (BRTO) of portal-systemic shunts (PSS), followed by PSE (PSE(+) group), and 11 patients underwent only transportal obliteration and/or BRTO of PSS (PSE(−) group).RESULTS:Portal venous pressures pretreatment was similar to posttreatment in the PSE(+) group, but lower than posttreatment in the PSE(−) group. Serum ammonia levels were higher at pretreatment than at 1 wk posttreatment in both groups, but the levels in the two groups were similar at pretreatment, 1 wk, 3 months, 3 yr, 4 yr, and 5 yr posttreatment. However, serum ammonia levels were lower in the PSE(+) group than in the PSE(−) group 6 months, 9 months, 1 yr, and 2 yr posttreatment. Grades of encephalopathy were higher at pretreatment than at 1 wk posttreatment in both groups, but the levels in the two groups were similar at pretreatment, 1 wk, 2 yr, 3 yr, 4 yr, and 5 yr posttreatment. However, grades of encephalopathy were lower in the PSE(+) group than in the PSE(−) group 3 months, 6 months, 9 months, and 1 yr posttreatment.CONCLUSIONS:Obliteration of PSS followed by PSE benefit patients with portal-systemic encephalopathy.


Transplant International | 2009

Diagnosis and treatment of pediatric patients with late-onset portal vein stenosis after living donor liver transplantation.

Youichi Kawano; Koichi Mizuta; Yasuhiko Sugawara; Satoshi Egami; Shuji Hisikawa; Yukihiro Sanada; Takehito Fujiwara; Yasunaru Sakuma; Masanobu Hyodo; Yoshiyuki Yoshida; Yoshikazu Yasuda; Eiji Sugimoto; Hideo Kawarasaki

Portal vein stenosis (PVS) after living donor liver transplantation (LDLT) is a serious complication that can lead to graft failure. Few studies of the diagnosis and treatment of late‐onset (≥3 months after liver transplantation) PVS have been reported. One hundred thirty‐three pediatric (median age 7.6 years, range 1.3–26.8 years) LDLT recipients were studied. The patients were followed by Doppler ultrasound (every 3 months) and multidetector helical computed tomography (once a year). Twelve patients were diagnosed with late‐onset PVS 0.5–6.9 years after LDLT. All cases were successfully treated with balloon dilatation. Five cases required multiple treatments. Early diagnosis of late‐onset PVS and interventional radiology therapy treatment may prevent graft loss.


Liver Transplantation | 2008

Rendezvous penetration method using double-balloon endoscopy for complete anastomosis obstruction of hepaticojejunostomy after pediatric living donor liver transplantation

Youichi Kawano; Koichi Mizuta; Shuji Hishikawa; Satoshi Egami; Takehito Fujiwara; Masanobu Hyodo; Yoshikazu Yasuda; Tomonori Yano; Katsuyuki Nakazawa; Hironori Yamamoto; Hideo Kawarasaki

A 12-year-old boy underwent a living donor liver transplantation at another facility in March 2006 after undergoing a failed Kasai operation. The left lobe from his mother was used for the graft with a single-orifice bile duct 4 mm in diameter. The biliary reconstruction was performed via a Roux-en-Y hepaticojejunostomy with an interrupted 6-0 absorbable monofilament suture material without a biliary stent. The patient was treated with tacrolimusand methylprednisolone-based immunosuppression. The postoperative course was uneventful, except for an episode of postoperative diabetes requiring a subcutaneous insulin injection. In September 2006, he was referred to our department because of intrahepatic bile duct dilatation. Image findings and laboratory data revealed biliary stricture with liver dysfunction. A percutaneous transhepatic cholangiodrainage (PTCD) was performed, with placement of a 7-French PTCD tube. Complete obstruction of the anastomosis was observed on cholangiography 2 weeks later. The PTCD tube was changed from a 7-French tube to a 9-French tube in order to observe the anastomosis with a 2.8-mm-diameter cholangioscope (CHF-CB30S, Olympus, Tokyo, Japan). This proved ineffective, however, as the guide wire could not be passed through the anastomosis. Because in our experience double-balloon endoscopy (DBE) can reveal the outline of a complete obstruction of hepaticojejunostomy, we were compelled to apply the rendezvous penetration method using DBE. RENDEZVOUS PENETRATION METHOD USING DBE


Transplantation Proceedings | 2010

Living-Donor Liver Transplantation in 126 Patients with Biliary Atresia: Single-Center Experience

Koichi Mizuta; Yukihiro Sanada; Taiichi Wakiya; Taizen Urahashi; Minoru Umehara; Satoshi Egami; Shuji Hishikawa; Noriki Okada; Youichi Kawano; T. Saito; Makoto Hayashida; S. Takahashi; H Yoshino; A. Shimizu; Y. Takatsuka; T. Kitamura; Y. Kita; T. Uno; Y. Yoshida; Masanobu Hyodo; Yasunaru Sakuma; Takehito Fujiwara; Kentaro Ushijima; K. Sugimoto; Masami Ohmori; S. Ohtomo; Koichi Sakamoto; Manabu Nakata; Tomonori Yano; Hironori Yamamoto

OBJECTIVES To describe our experience with 126 consecutive living-donor liver transplantation (LDLT) procedures performed because of biliary atresia and to evaluate the optimal timing of the operation. PATIENTS AND METHODS Between May 2001 and January 2010,126 patients with biliary atresia underwent 130 LDLT procedures. Mean (SD) patient age was 3.3 (4.2) years, and body weight was 13.8 (10.7) kg. Donors included 64 fathers, 63 mothers, and 3 other individuals. The left lateral segment was the most commonly used graft (75%). Patients were divided into 3 groups according to body weight: group 1, less than 8 kg (n = 40); group 2,8 to 20 kg (n = 63); and group 3, more than 20 kg (n = 23). Medical records were reviewed retrospectively. Follow up was 4.5 (2.7) years. RESULTS All group 3 donors underwent left lobectomy, and all group 1 donors underwent left lateral segmentectomy. No donors required a second operation or died. Comparison of the 3 groups demonstrated that recipient Pediatric End-Stage Liver Disease score in group 1 was highest, operative blood loss in group 2 was lowest (78 mL/kg), and operative time in group 3 was longest (1201 minutes). Hepatic artery complications occurred more frequently in group 1 (17.9%), and biliary stenosis (43.5%) and gastrointestinal perforation (8.7%) occurred more frequently in group 3. The overall patient survival rates at 1, 5, and 9 years was 98%, 97%, and 97%, respectively. Five-year patient survival rate in groups 1,2, and 3 were 92.5%, 100%, and 95.7%, respectively. Gastrointestinal perforation (n = 2) was the primary cause of death. CONCLUSIONS Living-donor liver transplantation is an effective treatment of biliary atresia, with good long-term outcome. It seems that the most suitable time to perform LDLT to treat biliary atresia is when the patient weighs 8 to 20 kg.


Transplantation Proceedings | 2009

Living Donor Liver Transplantation for Congenital Absence of the Portal Vein

Yukihiro Sanada; Koichi Mizuta; Youichi Kawano; Satoshi Egami; Makoto Hayashida; Taiichi Wakiya; M. Mori; Shuji Hishikawa; K. Morishima; Takehito Fujiwara; Yasunaru Sakuma; Masanobu Hyodo; Yoshikazu Yasuda; Eiji Kobayashi; Hideo Kawarasaki

The congenital absence of the portal vein (CAPV) is a rare venous malformation in which mesenteric venous blood drains directly into the systemic circulation. Liver transplantation (OLT) may be indicated for patients with symptomatic CAPV refractory to medical treatment, especially due to hyperammonemia, portosystemic encephalopathy, hepatopulmonary syndrome, or hepatic tumors. Because portal hypertension and collateral circulation do not occur with CAPV, significant splanchnic congestion may occur when the portocaval shunt is totally clamped during portal vein (PV) reconstruction in OLT. This phenomenon results in severe bowel edema and hemodynamic instability, which negatively impact the patients condition and postoperative recovery. We have successfully reconstructed the PV in living donor liver transplantation (LDLT) using a venous interposition graft, which was anastomosed end-to-side to the portocaval shunt by a partial side-clamp, using a patent round ligament of the liver, which was anastomosed end-to-end to the graft PV with preservation of both the portal and caval blood flows. Owing to the differences in anatomy among patients, at LDLT for CAPV liver transplant surgeons should seek to preserve both portal and caval blood flows.


Pediatric Transplantation | 2007

Growth curves of pediatric patients with biliary atresia following living donor liver transplantation: factors that influence post-transplantation growth.

Takeshi Saito; Koichi Mizuta; Shuji Hishikawa; Youichi Kawano; Yukihiro Sanada; Takehito Fujiwara; Yoshikazu Yasuda; Koichi Sugimoto; Koichi Sakamoto; Hideo Kawarasaki

Abstract:  We evaluated the growth curves of children with BA after LDLT, and identified factors influencing growth velocity one‐yr after LDLT (ΔZ). The clinical data of 51 children with BA, who had an LDLT at our center from 2001 to 2005, were retrospectively reviewed. The Z scores for height and weight, and ΔZ were studied. The correlation between ΔZ and various clinical factors was evaluated statistically. Multivariate stepwise analyses were performed for ΔZ. The average height and weight Z scores at the time of LDLT were −1.34 ± 1.36 (±s.d.) and −0.78 ± 1.15, respectively. Among 30 BA recipients with stable liver function after transplant, weight returned to normal one‐yr post‐transplantation. However, height did not return to normal even by the third post‐transplantation year. On multivariate analyses, 73% of the variance in height ΔZ could be accounted for by factors such as standardized height at the time of LDLT (proportion of variance: 38%), number of steroid pulse treatments (17%), donor age (10%), and the presence of HVS (9%). Fifty‐four percentage of the variance in weight ΔZ could be accounted for by factors such as standardized weight at the time of LDLT (37%) and the total steroid dose given (17%). Height and weight status at the time of LDLT likely have the strongest impact on ΔZ. Additional factors include steroid exposure, age of the living donor, and presence of HVS, all of which should be considered to improve post‐transplantation growth.


Human Pathology | 2014

Quantitative fluorescence in situ hybridization measurement of telomere length in skin with/without sun exposure or actinic keratosis

Hiroyuki Ikeda; Junko Aida; Atsushi Hatamochi; Yoichiro Hamasaki; Naotaka Izumiyama-Shimomura; Kenichi Nakamura; Naoshi Ishikawa; Steven S.S. Poon; Mutsunori Fujiwara; Ken-ichiro Tomita; Naoki Hiraishi; Mie Kuroiwa; Masaaki Matsuura; Yukihiro Sanada; Youichi Kawano; Tomio Arai; Kaiyo Takubo

Chromosomal and genomic instability due to telomere dysfunction is known to play an important role in carcinogenesis. To study telomere shortening in the epidermis surrounding actinic keratosis, we measured telomere lengths of basal, parabasal, and suprabasal cells in epidermis with actinic keratosis (actinic keratosis group, n = 18) and without actinic keratosis (sun-protected, n = 15, and sun-exposed, n = 13 groups) and in actinic keratosis itself as well as in dermal fibroblasts in the 3 groups, using quantitative fluorescence in situ hybridization. Among the 3 cell types, telomeres of basal cells were not always the longest, suggesting that tissue stem cells are not necessarily located among basal cells. Telomeres of basal cells in the sun-exposed group were shorter than those in the sun-protected group. Telomeres in the background of actinic keratosis and in actinic keratosis itself and those of fibroblasts in actinic keratosis were significantly shorter than those in the controls. Our findings demonstrate that sun exposure induces telomere shortening and that actinic keratosis arises from epidermis with shorter telomeres despite the absence of any histologic atypia.


PLOS ONE | 2014

Q-FISH measurement of hepatocyte telomere lengths in donor liver and graft after pediatric living-donor liver transplantation: donor age affects telomere length sustainability.

Youichi Kawano; Naoshi Ishikawa; Junko Aida; Yukihiro Sanada; Naotaka Izumiyama-Shimomura; Kenichi Nakamura; Steven S.S. Poon; Koshi Matsumoto; Koichi Mizuta; Eiji Uchida; Takashi Tajiri; Hideo Kawarasaki; Kaiyo Takubo

Along with the increasing need for living-donor liver transplantation (LDLT), the issue of organ shortage has become a serious problem. Therefore, the use of organs from elderly donors has been increasing. While the short-term results of LDLT have greatly improved, problems affecting the long-term outcome of transplant patients remain unsolved. Furthermore, since contradictory data have been reported with regard to the relationship between donor age and LT/LDLT outcome, the question of whether the use of elderly donors influences the long-term outcome of a graft after LT/LDLT remains unsettled. To address whether hepatocyte telomere length reflects the outcome of LDLT, we analyzed the telomere lengths of hepatocytes in informative biopsy samples from 12 paired donors and recipients (grafts) of pediatric LDLT more than 5 years after adult-to-child LDLT because of primary biliary atresia, using quantitative fluorescence in situ hybridization (Q-FISH). The telomere lengths in the paired samples showed a robust relationship between the donor and grafted hepatocytes (r = 0.765, p = 0.0038), demonstrating the feasibility of our Q-FISH method for cell-specific evaluation. While 8 pairs showed no significant difference between the telomere lengths for the donor and the recipient, the other 4 pairs showed significantly shorter telomeres in the recipient than in the donor. Multiple regression analysis revealed that the donors in the latter group were older than those in the former (p = 0.001). Despite the small number of subjects, this pilot study indicates that donor age is a crucial factor affecting telomere length sustainability in hepatocytes after pediatric LDLT, and that the telomeres in grafted livers may be elongated somewhat longer when the grafts are immunologically well controlled.


Surgery | 2012

The role of operative intervention in management of congenital extrahepatic portosystemic shunt

Yukihiro Sanada; Taizen Urahashi; Yoshiyuki Ihara; Taiichi Wakiya; Noriki Okada; Naoya Yamada; Satoshi Egami; Shuji Hishikawa; Youichi Kawano; Kentaro Ushijima; Shinya Otomo; Koichi Sakamoto; Manabu Nakata; Yoshikazu Yasuda; Koichi Mizuta

BACKGROUND AND AIMS Congenital extrahepatic portosystemic shunt (CEPS) is a rare venous malformation in which mesenteric venous blood drains directly into the systemic circulation. It is still a matter of debate whether conservative or operative strategies should be used to treat symptomatic CEPS. The aim of this study was to evaluate the role of operative intervention in the management of CEPS. METHODS Between June 2004 and August 2010, 6 consecutive patients with symptomatic CEPS were treated in our department. There were 3 male and 3 female patients, with a median age of 3.5 years (range, 1-8). Their demographic, clinical, and laboratory data were analyzed. All patients were scheduled to undergo shunt ligation or liver transplantation (LT). RESULTS Living donor LT was carried out in 4 patients, and shunt ligation in 2. After a median follow-up of 25 months, all the patients are alive currently with marked relief of symptoms. CONCLUSION Shunt ligation or LT for symptomatic CEPS is potentially curative.


Transplant International | 2014

Maternal grafts protect daughter recipients from acute cellular rejection after pediatric living donor liver transplantation for biliary atresia

Yukihiro Sanada; Youichi Kawano; Atsushi Miki; Junko Aida; Kenichi Nakamura; Naotaka Shimomura; Naoshi Ishikawa; Tomio Arai; Yuta Hirata; Naoya Yamada; Noriki Okada; Taiichi Wakiya; Yoshiyuki Ihara; Taizen Urahashi; Yoshikazu Yasuda; Kaiyo Takubo; Koichi Mizuta

Some studies have found that gender mismatch between donors and recipients are related to poor graft prognosis after liver transplantation. However, few studies have investigated the impact of gender mismatch on acute cellular rejection (ACR) in pediatric living donor liver transplantation (LDLT). This retrospective study investigated the clinical significance of these factors in ACR after pediatric LDLT. Between November 2001 and February 2012, 114 LDLTs were performed for recipients with biliary atresia (BA) using parental grafts. We performed univariate and multivariate analyses to identify the factors associated with ACR. The donor–recipient classifications included mother donor to daughter recipient (MD; n = 43), mother to son (n = 18), father to daughter (FD; n = 33), and father to son (n = 20) groups. The overall incidence rate of ACR in the recipients was 36.8%. Multivariate analysis showed that gender mismatch alone was an independent risk factor for ACR (P = 0.012). The FD group had a higher incidence of ACR than the MD group (P = 0.002). In LDLT, paternal grafts with gender mismatch were associated with a higher increased incidence of ACR than maternal grafts with gender match. Our findings support the possibility that maternal antigens may have an important clinical impact on graft tolerance in LDLT for patients with BA.

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Koichi Mizuta

Jichi Medical University

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