Publications by authors named "Hirotaka Okamoto"

Postoperative pancreatic fistula (POPF) remains a major and serious problem after pancreaticoduodenectomy (PD). In its presence, pancreatic juice may leak from the main duct or branches of the pancreatic stump. To prevent this, we have applied a newly modified anastomosis of pancreaticogastrostomy (PG) using a linear stapler (stapled PG).

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We experimentally clarify the interaction of acoustic pressure and heat release rate fluctuations during a transition to high-frequency combustion instability in a model rocket engine combustor. The dynamical state of acoustic pressure fluctuations undergoes a transition from high-dimensional chaotic oscillations to strongly correlated limit cycle oscillations. The coherent structure in the heat release rate field emerges with the initiation of weakly correlated limit cycle oscillations.

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Background: The tumor vascular microenvironment has an important role in tumor progression and metastasis. The objective of this study was to assess the significance of metastatic hepatic tumor vascular microenvironment in relation to the response to systemic fluorouracil-based chemotherapy [folinic acid/fluorouracil/oxaliplatin (FOLFOX) or folinic acid/fluorouracil/irinotecan (FOLFIRI)].

Patients And Methods: A total of 48 consecutive patients with colorectal cancer (CRC) with hepatic metastasis were retrospectively reviewed, and factors such as metastatic tumor vascular microenvironment, chemotherapy response and hepatic resection, were analyzed.

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Background: Combination of choledochocele and extra-hepatic duct duplication is an extremely rare congenital abnormality.

Case Presentation: The patient was an 81-year-old Japanese man. He visited the emergency room for severe abdominal colic pain.

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Introduction: Biliary enteric anastomosis is a well-known biliary reconstruction method. Anastomosis stricture is one of the complications of this procedure that occurs in some patients over the long-term. We report a successful case of hepatic ductoplasty combined with hepaticojejunostomy (H-J) for the treatment of iatrogenic Bismuth type 2 stricture.

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There is an increasing demand for highly thermally conductive and electrically insulating polymer materials for next-generation electronic devices, power systems, and communication equipment. Boron nitride nanosheets (BNNSs) are insulating materials with extremely high thermal conductivity. However, BNNSs suffer from the lack of facile and low-cost methods for producing large volumes of BNNSs, and extremely low through-plane thermal conductivities of BNNS/polymer composites as compared to the in-plane thermal conductivities.

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A single incisional laparoscopic surgery (SILS) approach is increasingly being used, taking advantage of the minimally invasive technique. The aim of this study was to evaluate the feasibility and the validation of SILS procedure for small bowel obstruction (SBO). Sixteen consecutive patients with SBO who underwent SILS release of ileus between April 2010 and March 2015 were compared with the conventional multiport laparoscopic treatment group of 16 patients matched for age, gender, and surgical procedure.

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Boron nitride nanosheets (BNNSs) with micron-sized edges were prepared in high yields by direct exfoliation of bulk hexagonal boron nitrides using ionic liquids (ILs). The ILs strongly attached onto BNNS surfaces, and dramatically enhanced the exfoliation, giving highly concentrated BNNS dispersions (∼1.9 mg mL(-1)) and yields reaching ∼50%.

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We report a case of typical fibrolamellar hepatocellular carcinoma (FL-HCC) in a 16-year-old Japanese boy. This is very rare malignancy in Japan. The patient was referred for investigation of a large hepatic tumor and the results of tests for hepatitis B virus surface antigen and hepatitis C virus antibody were negative.

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Single-incisional laparoscopic surgery (SILS) has emerged as an attempt to further enhance the cosmetic benefits and reduce the morbidity of minimally invasive surgery. We present an approach of SILS adhesiolysis to adhesive strangulated ileus. A 70-year-old female patient, who had undergone laparoscopic low anterior resection 6 years before, underwent SILS adhesiolysis to a midline surgical incision wound adhesion site.

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A case of invasive ductal carcinoma of an ectopic pancreas in the stomach in a 74-year-old woman is presented. A 4.0 cm gastric submucosal tumor (SMT) was resected surgically.

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Alkyl-modified crystalline silicon nanosheets 2 were synthesized and maintained the crystal structure of a Si(111) plane, in which the dangling silicon bond is stabilized by capping with the alkyl group. 2 was characterized using UV-vis, Fourier transform-infrared, and X-ray photoelectron spectroscopies; X-ray diffraction; and X-ray absorption near edge structure analysis. A model structure is proposed that has a periodicity through the nanosheet surface.

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Hemosuccus pancreaticus is an unusual cause of gastrointestinal bleeding that occurs as a complication of chronic or acute pancreatitis. We report a case of extremely acute-onset hemosuccus pancreaticus occurring in a patient with chronic pancreatitis over a long-term follow-up after a Puestow procedure (side-to-side pancreaticojejunostomy). The patient was admitted to our hospital due to severe anemia and tarry stools indicative of gastrointestinal bleeding.

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Silicon nanomaterials and nanostructures exhibit different properties from those of bulk silicon materials based on quantum confinement effects. They are expected to lead to the development of new applications of silicon, in addition to wide use in semiconductor devices. Aside from industrial interest, intriguing issues of academic interest still remain with respect to the origins of their characteristic properties.

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The present study reports a case involving a 17-year-old man who was brought to the emergency department of our hospital with severe upper abdominal pain following a blow received in a rugby game. Emergency computed tomography (CT) revealed severe pancreatic neck injury, and the patient was subsequently given conservative treatment in the High Care Unit. Forty-eight hours later, follow-up enhanced CT revealed that the pancreas was clearly lacerated and the amount of peripancreatic fluid was increasing; furthermore, serum amylase and elastase levels were elevated.

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The synthesis of silicon nanosheets for fabricating electronic devices, without using conventional vacuum processes and vapor deposition, is challenging and is anticipated to receive significant attention for a wide range of applications. Here, we report the synthesis of oxygen-free, phenyl-modified organosilicon nanosheets with atomic thickness. In organic solvents, a consequence of this new silicon structure is its uniform dispersion and the possibility of exfoliation into unilamellar nanosheets.

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Silicon nanomaterials are encouraging candidates for application to photonic, electronic, or biosensing devices, due to their size-quantization effects. Two-dimensional silicon nanosheets could help to realize a widespread quantum field, because of their nanoscale thickness and microscale area. However, there has been no example of a successful synthesis of two-dimensional silicon nanomaterials with large lateral size and oxygen-free surfaces.

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Small-cell carcinoma of the gallbladder is a very rare tumor. In this report, we describe a patient with small-cell carcinoma combined with adenocarcinoma in the gallbladder. The patient was a 70-year-old man, who clinically manifested systemic lymphadenopathy.

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Epithelial tumors forming a mass in the male nipple are very rare. Paget's disease, adenoma of the nipple (AON), and breast cancer must be considered for differential diagnosis. This report presents a 72-year-old man with spontaneous serous nipple discharge and an enlarged nipple measuring 2 cm in diameter.

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