Yasuhiro Ohtsuka

Chiba University, Tiba, Chiba, Japan

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Publications (22)40.54 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Pancreaticobiliary maljunction (PBM), which frequently accompanies choledochal dilation, is a high risk factor for biliary tract (gallbladder, bile duct) carcinoma because of the continuous reflux of pancreatic juice into the biliary tract. The aim of this study was to clarify the preferable operative age in PBM patients for the prevention of biliary tract carcinogenesis, with reference to the dilation types of bile ducts. There were 165 PBM patients in total studied, including 92 pediatric patients (< or =15 y) (cystic, 63; spindle-like, 29; nondilation, 0) and 73 adult patients (>15 y) (cystic, 45; spindle-like, 18; nondilation, 10) who underwent operative excision of extrahepatic bile ducts or cholecystectomy. We investigated incidence by age of biliary tract malignancies and the risk according to types of dilation. In the pediatric group, no carcinoma case could be found preoperatively or postoperatively (mean follow-up period, 11.7 y). In the adult group, bile duct carcinomas could be detected in 6 cases of a cystic type (6 of 45; 13.3%) (3 preoperative, 3 postoperative). Among the bile duct carcinoma cases, the youngest patient was a 21-year-old woman who had undergone excision of an extrahepatic bile duct 3 years previously. Gallbladder carcinomas were detected in 16 patients: 3 of 45 cystic (6.7%), 6 of 18 spindle-like (33.3%), and 8 of 10 nondilation (80.0%), in whom the youngest patient was a 41-year-old woman with a spindle-like type. To prevent biliary tract carcinogenesis in PBM patients, cystic-dilated choledochus should be excised in childhood before the development to a precancerous stage. In spindle-like and nondilation types, cholecystectomy is absolutely necessary in early adulthood before age 40.
    Surgery 02/2006; 139(1):33-8. DOI:10.1016/j.surg.2005.07.028 · 3.38 Impact Factor
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    ABSTRACT: Advanced neuroblastoma and malignant liver tumor are representative childhood cancers for which combined chemotherapy including cisplatin and doxorubicin is routinely performed. The prognosis of patients with tumors which develop multiple drug resistance (MDR) is unfavorable. To elucidate the role of multidrug resistance-associated protein (MRP) and canalicular multispecific organic anion transporter (cMOAT) in the clinical behavior of the tumors, we examined 42 neuroblastomas and 10 malignant liver tumors for the expressions of MRP and cMOAT by quantitative RNA-polymerase chain reaction (PCR). The amplification and expression of N-myc oncogene in the neuroblastomas were also investigated. We found a close association between MRP and N-myc expression in each neuroblastoma sample but no significant relationship between MRP expression and the patients' outcome. The forced expression of N-myc failed to enhance the expression of MRP in N-myc transfected neuroblastoma cell lines. cMOAT was rarely expressed in the neuroblastomas, but was frequently expressed in the malignant liver tumors. The expression of MRP and cMOAT in the childhood liver tumors was more common and higher, especially in advanced cases with a poor outcome, than that observed in normal liver or in 9 hepatocellular carcinomas from adult patients. The enhanced expression of these genes might be characteristic of childhood malignant liver tumors and related to their clinical chemoresistance.
    Cancer Science 08/2005; 89(12):1276 - 1283. DOI:10.1111/j.1349-7006.1998.tb00524.x · 3.52 Impact Factor
  • T Okada · H Yoshida · T Matsunaga · K Kouchi · Y Ohtsuka · T Saitou · N Ohnuma ·
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    ABSTRACT: We hypothesized that hyperbaric oxygenation (HBO) combined with a long tube (LT) [HBO + LT] would be more effective than HBO combined with a short tube (ST) [HBO + ST] for simple adhesive postoperative intestinal obstruction (APIO) in children, assuming that there is synergism between HBO and LT. The objective of this study was to determine retrospectively the effect of HBO + LT compared to HBO + ST for simple APIO in children. Seventy-three patients were diagnosed with simple APIO, and 51 of these patients were treated with HBO + LT during 104 HBO sessions, while 22 were treated with HBO + ST during 34 HBO sessions. HBO was performed at a pressure of 2 atmospheres for 60 minutes once daily. The recovery rates after HBO therapy were 87.5 % for the HBO + LT group and 82.4 % for the HBO + ST group (p = 0.4496). HBO was performed 5 +/- 3 (range 1 to 15) times for the HBO + LT group and 4 +/- 2 (range 1 to 8) times for the HBO + ST group (p = 0.9847) for ultimate recovery from simple APIO. The recovery rate after HBO therapy of up to 6 sessions was 78.2 % for HBO + LT and 92.1 % for HBO + ST (p = 0.0360) among the cases that recovered ultimately. The effect of HBO + LT did not significantly differ from that of HBO + ST, but the insertion of an LT is more intricate and the cost is higher than that of an ST. Therefore, we conclude that the use of an LT is not necessarily required for HBO therapy for simple APIO.
    European Journal of Pediatric Surgery 09/2004; 14(4):240-4. DOI:10.1055/s-2004-820902 · 0.99 Impact Factor
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    ABSTRACT: To investigate the optimal strategy of preoperative transcatheter arterial chemoembolization (TACE) for hepatoblastoma. Between 1992 and 2001, 7 children with hepatoblastoma (aged 9 months to 13 years) underwent preoperative TACE. The chemoembolic agent used was an emulsion of pirarubicin and lipiodol. Four patients without distant metastasis underwent "primary" TACE without systemic chemotherapy. The other 3 with distant metastases underwent "delayed" TACE following systemic chemotherapy. These patients were all examined retrospectively using clinical data. The average dosage of lipiodol was 0.6 ml per tumor maximal diameter (cm). All the primary cases showed a significant decrease in alpha-fetoprotein (AFP) and a reduction in the tumor size. They consequently underwent a complete surgical resection and are now disease free. All the delayed cases showed a slight decrease in AFP and underwent complete surgical resection; however, two of them died of lung metastases, and the other died of a second malignancy. Regarding complications, liver dysfunction and pulmonary embolism occurred in one patient each. For patients without distant metastasis, regardless of the resectability of the primary tumor, TACE may be considered the initial and only preoperative treatment, and it may be repeated. For patients with distant metastases, their complete eradication with systemic chemotherapy prior to TACE is essential.
    Surgery Today 02/2004; 34(2):127-33. DOI:10.1007/s00595-003-2663-7 · 1.53 Impact Factor
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    ABSTRACT: Multilocular cyst of the kidney is an uncommon benign renal neoplasm. Because of its benign nature, this lesion is best managed by nephron-sparing surgery. This report describes a child who underwent a partial nephrectomy for a multilocular cyst of the kidney. After reviewing other cases, we discuss the clinical characteristics of multilocular cyst of the kidney and emphasize the cystic partially differentiated nephroblastoma as a differential diagnosis.
    Journal of Pediatric Surgery 12/2003; 38(11):1689-92. DOI:10.1016/S0022-3468(03)00589-X · 1.39 Impact Factor
  • K Kouch · H Yoshida · T Matsunaga · Y Ohtsuka · T Okada · T Saito · G Matsuura · H Yamada · N Ohnuma ·
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    ABSTRACT: A mass-screened neuroblastoma (MSN) shows low-grade malignancy. Although the tumor is small, open laparotomy requires a large incision. Purpose: Extirpation by retroperitoneoscopy (ER) was performed in children with MSN to reduce the surgical stress. The indications for ER were (1) MSN originating from the adrenal gland and (2) a tumor size of less than 4 cm. Between January 2000 and June 2002, 6 children (mean age: 8.5 +/- 0.6 months) underwent ER. All children successfully underwent ER and no conversion of laparoscopy to open surgery was required. The only complication in one patient was a peritoneal tear. Oral intake was possible in all children the day after the operation. No port site metastasis or local recurrence was observed during follow-up (15 to 29 months). Adrenal MSN less than 4 cm were successfully extirpated by ER. This method has the advantage of allowing patients an early return to eating and has no risk of postoperative ileus. ER is an available surgical technique for children with MSN less than 4 cm.
    Surgical Endoscopy 12/2003; 17(11):1769-72. DOI:10.1007/s00464-002-8742-9 · 3.26 Impact Factor
  • T Okada · H Yoshida · T Matsunaga · K Kouchi · Y Ohtsuka · T Saitou · G Matsuura · N Ohnuma ·
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    ABSTRACT: Conservative management of multicystic dysplastic kidney (MCDK) without nephrectomy has recently been advocated. The purpose of this study was to determine the clinical course of conservatively managed unilateral MCDK detected prenatally. Between 1991 and 2001, ten children (three boys and seven girls) with unilateral MCDK detected by prenatal ultrasonography (US) were prospectively followed at our institution. At birth, US confirmed the prenatal findings in all cases. All patients underwent voiding cystourethrography, intravenous pyelography, and radionuclide scans. Postnatal follow-up US examinations were performed every 3 months until patients were 5 years old and annually from then forward. The mean age at diagnosis during the prenatal period was 29 weeks of gestation (range 21-38 weeks). Median follow-up time was 42 months (range 17-125 months). Follow-up US was performed in eight children; three (38%) showed partial resolution, three (38%) complete resolution, and two (24%) no change in cyst size. The mean age at complete resolution of the lesion was 23 months (range 9-33 months). No children developed hypertension or tumors, and all maintained normal growth. In the present study, the natural history of MCDK was benign, and serial US monitoring showed that the affected kidneys frequently showed resolution with time. The results of this study support the conclusion that a nonsurgical approach for patients with MCDK is advisable.
    Pediatric Surgery International 06/2003; 19(3):207-10. DOI:10.1007/s00383-002-0920-2 · 1.00 Impact Factor
  • Y Ohtsuka · K Iwasaki · S Okazumi · H Yoshida · T Matsunaga · K Kouchi · T Okada · N Ohnuma ·
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    ABSTRACT: We reviewed our experience to determine the usefulness of emergency transcatheter arterial embolization (TAE) for severe blunt hepatic injury (BHI) in children. Between 1978 and 2000, 21 children with BHI (14 boys and 7 girls, ranging in age from 2 to 14 years) were managed according to our protocol. The patients who were hemodynamically stable, and had no other associated injury requiring laparotomy, regardless of the hepatic injury grade, were managed nonsurgically. Emergency angiography and TAE performed after a CT scan revealed extravasation of the contrast medium. Of the 21 patients, 3 underwent emergency laparotomy; 2 due to hemodynamic instability despite fluid resuscitation (1 died), and the 3rd patient because of associated injury. The other 18 patients (86%) were initially managed nonsurgically; however, 2 underwent delayed laparotomy because of complications (1 each of suspected delayed hepatic hemorrhage and liver abscess). Nonsurgical management was completed in the remaining 16 (89%) with no morbidity and mortality. Two of the 16 returned to a hemodynamically stable condition with fluid resuscitation, but were compromised with persistent hepatic hemorrhage, and were successfully treated with emergency TAE. We propose that emergency TAE should be considered as an initial treatment for severe BHI in children.
    Pediatric Surgery International 05/2003; 19(1-2):29-34. DOI:10.1007/s00383-002-0889-x · 1.00 Impact Factor
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    ABSTRACT: We describe a 13-year-old girl who underwent insertion of a Flexima biliary stent for obstructive jaundice due to compression of the extrahepatic bile duct by an enlarged lymph node secondary to neuroblastoma. This novel endoscopic internal biliary drainage procedure was safe and effective even for a child, and improved her quality of life. We further review other treatment options available for malignant obstructive jaundice in children.
    Pediatric Radiology 03/2003; 33(2):133-5. DOI:10.1007/s00247-002-0781-9 · 1.57 Impact Factor
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    ABSTRACT: The aim of this study was to establish the optimal management strategy of congenital biliary dilatation (CBD) in early infancy. Over the last 15 years, 14 patients with CBD in early infancy (within 5 months), including 3 antenatally diagnosed patients, were treated in the authors' department. Of the 14 patients, 7 (50%) underwent early definitive surgery (E group), and the other 7 (50%) underwent delayed primary definitive surgery after percutaneous transhepatic cholangiodrainage (PTCD; D group). Both groups were compared retrospectively using clinical data. Pretreatment status and backgrounds of the patients were clinically homogeneous between the 2 groups. The total length of hospital stay was significantly longer in the D group. As short-term complications, 1 patient in the E group was compromised with hepatolithiasis, and 3 patients in the D group were compromised with catheter-related complications. Other clinical data, such as age at definitive surgery, blood loss, pathologic fibrosis of the liver, jaundice-free day, and long-term complications were not significantly different between the 2 groups. The authors propose that the standard of management should be early definitive surgery with wide anastomosis before 2 months of age. However, PTCD might be used under strict consideration of indication and careful management for patients with extremely poor surgical risk.
    Journal of Pediatric Surgery 09/2002; 37(8):1173-6. DOI:10.1053/jpsu.2002.34466 · 1.39 Impact Factor
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    ABSTRACT: Paraovarian cyst is very uncommon in children, and its preoperative diagnosis is difficult. This report describes 2 cases of surgically proven paraovarian cyst with torsion. It is important to be aware of torsion as a complication of paraovarian cyst.
    Journal of Pediatric Surgery 07/2002; 37(6):937-40. DOI:10.1053/jpsu.2002.32922 · 1.39 Impact Factor
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    ABSTRACT: The authors report the successful use of endoscopic ultrasonography (EUS) for finding the etiology and subsequent treatment strategy for esophageal stenosis in 2 children. In case 1, EUS showed anterior wall thickening and multiple low echoic regions in the mp layer. These regions were believed to be cartilage. Esophageal resection therefore was performed. In case 2, EUS showed disruption of the sm and mp layers at the stenosis, leading us to speculate that the stenosis was caused by gastroesophageal reflux. After balloon dilatation, he underwent antireflux surgery of Nissen's fundoplication. EUS was useful for determining the etiology of esophageal stenosis and, thus, the appropriate treatment strategy.
    Journal of Pediatric Surgery 07/2002; 37(6):934-6. DOI:10.1053/jpsu.2002.32921 · 1.39 Impact Factor
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    ABSTRACT: The authors report on 2 patients with congenital chylous ascites who underwent successful lymphatic duct ligation after a laparoscopic lymphoid dye test. Fetal ascites had been detected in both cases, and both babies were born with marked abdominal swelling. Given that conservative treatment by medium-chain triglyceride (MCT) milk and total parenteral nutrition (TPN) was ineffective, the authors elected to perform lymphatic duct ligation on the 95th postnatal day in the former case and on the 27th postnatal day in the latter case. Lipophilic dye was administered preoperatively both through oral and subcutaneous routes, and the peritoneal cavity was explored using laparoscopy. This laparoscopic lymphoid dye test precisely identified the area of chylous leakage, and the authors were able to repair the malformed lymphatic duct directly at laparotomy. Both postoperative courses have been favorable with no recurrence of symptoms. The lymphatic duct ligation should be considered in cases resistant to conservative treatment for over a month. The present laparoscopic lymphoid dye test is a novel and useful procedure that allows surgeons to identify the exact location of chylous leakage, and thus successfully ligate the lymphatic duct.
    Journal of Pediatric Surgery 12/2001; 36(11):1717-9. DOI:10.1053/jpsu.2001.27973 · 1.39 Impact Factor
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    ABSTRACT: Most umbilical hernias in children close spontaneously. Complications associated with umbilical hernias are rarely observed during follow-up. We report herein a 5-month-old girl with a strangulated umbilical hernia. Her umbilicus was hard, reddish, and irreducible. Plain radiography of the abdomen showed signs of mechanical ileus. The patient was thus diagnosed to have a strangulated umbilical hernia. A 5-cm section of the ascending colon and a 5-cm section of the terminal ileum, as well as the cecum and appendix, were congested, edematous, and erythematous, and together were enclosed by a firm hernial ring. A closure of the fascial defect and umbilicoplasty were performed. The postoperative course was uneventful. In patients with infantile umbilical hernias, strangulation may occur as the fascial defect decreases in size.
    Surgery Today 04/2001; 31(6):546-549. DOI:10.1007/s005950170120 · 1.53 Impact Factor
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    ABSTRACT: It is difficult to detect the arcuate or cortical renal arteries when performing pulsed Doppler sonography (PDS) for congenital hydronephrosis. This study was undergone to assess the usefulness of PDS of the hilar renal artery to differentiate obstructive from nonobstructive hydronephrosis. The authors performed PDS of the hilar renal artery in 80 normal children: 20 aged 0 to 1 months (group I), 20 aged 1 to 12 months (group II), 20 aged 1 to 6 years (group III), and 20 aged 7 to 15 years (group IV). Based on diuretic renography findings, 22 kidneys from 19 children with a ureteropelvic junction (UPJ) stricture were divided into 7 dilated obstructed and 15 dilated nonobstructed kidneys. The peak-systolic velocity (PSV), end-diastolic velocity (EDV), mean average velocity (Vm) and the resistive index (RI = [PSV - EDV]/PSV) were measured at the hilar renal artery. There was a significant difference in the RI of the hilar renal artery between obstructive and nonobstructive hydronephrosis. A pulsed Doppler evaluation of the hilar renal artery is useful for detecting an obstructive UPJ stricture compared with assessing arcuate or cortical renal arteries.
    Journal of Pediatric Surgery 04/2001; 36(3):416-20. DOI:10.1053/jpsu.2001.21607 · 1.39 Impact Factor
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    ABSTRACT: This study was undertaken to assess the usefulness of pulsed Doppler sonography (PDS) for the detection of strangulation in small bowel obstruction by evaluating the hemodynamics in the superior mesenteric artery (SMA). The authors performed PDS in 117 normal children: 22 children aged 0 to 1 months (group I), 27 children aged 1 to 12 months (group II), 36 children aged 1 to 6 years (group III), and 32 children aged 7 to 15 years (group IV). Patients included 25 with simple obstruction: 1 in group II, 10 in group III, and 14 in group IV; and 9 with strangulating obstruction: 2 in group I, 2 in group II, 3 in group III, and 2 in group IV. The authors measured the peak-systolic velocity, end-diastolic velocity (EDV), and mean average velocity and calculated the resistive index (RI). The authors observed both a significant decrease in the EDV and increase in the RI for the SMA in strangulating obstruction compared with simple obstruction. Analysis of the hemodynamics in the SMA using PDS is useful to differentiate strangulating obstruction from simple obstruction.
    Journal of Pediatric Surgery 04/2001; 36(3):430-5. DOI:10.1053/jpsu.2001.21602 · 1.39 Impact Factor
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    ABSTRACT: Bronchopulmonary sequestration (PS) is characterized by non-functioning lung tissue fed from one or several aberrant systemic arteries. The condition is diagnosed by visualizing the feeding arteries using non-invasive CT, MRI, colour Doppler sonography or conventional angiography. We present a 5-year-old boy in whom intralobar sequestration was diagnosed using contrast-enhanced 3D MR angiography, which visualised fine blood vessels in the thoraco-abdominal region without arterial puncture. This technique is useful for diagnosing PS.
    Pediatric Radiology 12/2000; 30(11):774-5. DOI:10.1007/s002470000329 · 1.57 Impact Factor
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    ABSTRACT: A substantial fraction of neuroblastomas found by mass screening have been suggested to regress spontaneously because of the high incidence of infantile neuroblastomas in the screening population. In this study, 70 neuroblastomas were analyzed for expression of proto-oncogenes related to neuronal differentiation to clarify the biological significance of proto-oncogene expression in the screening-positive and -negative tumors. The tumors consisted of 39 neuroblastomas found by screening (group 1), 16 non-N-myc-amplified neuroblastomas found by clinical symptom(s) (group 2), and 15 N-myc-amplified neuroblastomas found by clinical symptom(s) (group 3). The expression of c-src, trk A, and N-myc in tumor tissues was analyzed by quantitative RNA PCR. Neuronal c-srcN2 expression varied significantly in the following order: group 1 > group 2 > group 3. The level of expression of trk A was markedly reduced in group 3 but did not differ in groups 1 and 2. Most tumors in group 3 overexpressed N-myc. However, N-myc expression in group 1 was significantly higher than that in group 2. Thus, the characteristics of proto-oncogene expression in screening-positive tumors included enhanced expression of c-srcN2 and N-myc mRNA, regardless of nonamplification of N-myc. Our results suggest that the role of N-myc differs in neuroblastomas detected by screening and in N-myc-amplified tumors.
    Clinical Cancer Research 08/2000; 6(8):3199-204. · 8.72 Impact Factor

  • Nihon Rinsho Geka Gakkai Zasshi (Journal of Japan Surgical Association) 01/2000; 61(9):2381-2385. DOI:10.3919/jjsa.61.2381
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    ABSTRACT: Nonoperative management for blunt pancreatic injury in children was performed between 1977 and 1998. The efficiency and safety of nonoperative management was examined. Pancreatic injury was diagnosed in 20 children. The surgical indication was determined by hemodynamic instability and the management of associated injuries. Children without surgical indications were treated initially by nonoperative management. Nineteen of 20 children were treated initially nonoperatively, and 18 of the 19 survived. Surgical exploration was performed in only 1 child with perforation of the duodenum and bile duct. One child died of complications of total parenteral nutrition. Ultrasound scan and computed tomography scan showed pancreatic contusion in 9, laceration in 6, and injury of the main pancreatic duct (MPD) in 5. Pseudocysts were detected in 10 (5 laceration and 5 MPD injury). Pseudocysts smaller than 10 cm disappeared after nonoperative management, and those larger than 10 cm required operative management. Rupture of pseudocysts occurred in 2 children by rotating the upper torso. Nonoperative management of pancreatic injuries is effective in children, although careful management is required to avoid complications. Pseudocysts smaller than 10 cm were treated successfully by nonoperative management, and those larger than 10 cm required surgical management.
    Journal of Pediatric Surgery 12/1999; 34(11):1736-9. DOI:10.1016/S0022-3468(99)90657-7 · 1.39 Impact Factor

Publication Stats

296 Citations
40.54 Total Impact Points


  • 2000-2006
    • Chiba University
      • Department of Pediatric Surgery
      Tiba, Chiba, Japan
  • 2002
    • Chiba Children's Hospital
      Tiba, Chiba, Japan
    • Saitama Cancer Center
      Саитама, Saitama, Japan