Yuen Nakase

Cisplatin incorporated in microspheres: development and fundamental studies for its clinical application

A new drug delivery formulation, biodegradable glycolic acid-lactic acid copolymer (PGLA) microspheres incorporating cisplatin (CDDP-MS) has been developed for the treatment of peritoneal carcinomatosis. Scanning electron microscopy showed that CDDP-MS has a smooth surface and few cisplatin crystals in the hollow. An electron probe micro analyzer revealed that cisplatin was located mainly in the matrix in the state of a molecule. Release profile in vitro of CDDP from microspheres showed that the initial burst was 21.2% and the remaining CDDP was released slowly thenceforth over 14 days. Hydrolysis of CDDP-MS progresses very slowly during the 14 days, but there was no morphological change in the SEM views. The dimethylformamide content entrapped within CDDP-MS, determined by a gas chromatography, was 136 ppm at the evaporation temperature of 47 degrees C. The 50% lethal dose value of CDDP-MS, calculated by the Litchfield-Wilcoxon method, was reduced to 57% of the cisplatin solution. Therapeutic experiment on mice with peritoneal carcinomatosis showed that CDDP-MS did not enhance therapeutic effect as compared with the same dose dosage of a cisplatin aqueous solution but large quantities of cisplatin could be given in case of CDDP-MS owing to less toxicity.

Regeneration of skeletal muscle using in situ tissue engineering on an acellular collagen sponge scaffold in a rabbit model.

Because of the limited ability of skeletal muscle to regenerate, resection of a large amount of muscle mass often results in incomplete recovery due to nonfunctional scar tissue. The aim of this study was to regenerate skeletal muscle using in situ tissue engineering in a rabbit model. In 18 male rabbits, a muscle defect (1.0 × ∼1.0 × ∼0.5 cm) was created in the vastus lateralis of both legs. A piece of cross-linked atelocollagen sponge was then inserted into the defect in one leg, whereas the defect in the other leg was left untreated. Both defects were finally covered with fascia. Twenty-four weeks after surgery, the defect that had been filled with the cross-linked atelocollagen sponge scaffold showed mild concavity and slight adhesion to the fascia, while the control side showed severe scar formation and shrinkage. Histologically, the regenerating myofibers at the site containing the collagen sponge were greater in number, diameter, and length than those at the control site. These results indicate that cross-linked atelocollagen sponge has the potential to act as a scaffold for muscle tissue regeneration.

Hemobilia and cystic artery stump pseudoaneurysm associated with liver abscess after a laparoscopic cholecystectomy: report of a case.

A 63-year-old woman was admitted for cholecystitis and underwent a laparoscopic cholecystectomy (LC). She experienced abdominal pain and hemobilia 11 days after the LC. Angiography was performed but it did not show any source of bleeding. Thereafter, at 27 days after LC, a repeat angiogram was performed which revealed a pseudoaneurysm (PA) arising from a cystic artery stump and an embolized PA sack. However, another PA arising from near the embolized PA and liver abscess was observed 4 days after embolization. The arterial collateral flow was evaluated by endovascular balloon occlusion of the right hepatic artery and it was embolized proximal and distal to the bleeding point. The embolization of the partial hepatic artery was effective for PA when packing the PA sack proved to be insufficient. In patients with liver cirrhosis or liver abscess who require an adequate arterial liver flow, it is important to evaluate the collateral arterial flow before hepatic artery embolization.

Efficacy of the modified anvil grasper for laparoscopic intra-corporeal circular stapled anastomosis

The traditional anvil grasper may be difficult to use for connecting the stem of an anvil with the centre rod of a circular stapler because the grasper holds the anvil completely still. In addition, the head angle is fixed and cannot handle the anvil head delicately in a tight pelvic space. Many surgeons use a grasper designed for holding the bowel or a dissector for holding the anvil during intra-corporeal circular stapled anastomosis during low anterior resection, sigmoidectomy, left hemi colectomy and know that it is difficult to connect segments with these instruments due to slipping. A new modified anvil grasper was developed with curved blades that can easily grasp the stem of an anvil and smoothly connect it with the centre rod of the circular stapler. This grasper should be useful for surgeons performing laparoscopic intra-corporeal circular stapled anastomoses, which are the most challenging part of laparoscopic colorectal surgery.

Usefulness of a novel, slim long syringe-like device for applying surgical mesh through a 5-mm trocar: A novel mesh applier

We developed a device for introducing surgical mesh through a 5‐mm trocar during transabdominal preperitoneal hernia repair. This device is like a slim long syringe; it has a polypropylene outer sheath (outer diameter, 5.8 mm; inner diameter, 5.6 mm; length, 2500 mm) and inner rod, and is made in a similar manner to a drinking straw. Therefore, the manufacturing costs are low. To use the device, folded mesh is placed inside it with a grasper before surgery. The device is then inserted through the trocar, and the mesh is pushed out by the inner rod and applied. The folded mesh extrudes smoothly pubis side to lateral side along the inguinal curve. It reinforces the area without any contamination and expands in a manner that makes it easy for the surgeon to place and fix the mesh. Our device allows mesh to be applied smoothly, comfortably, and economically, and it may reduce the risk of infection.

Usefulness of the novel evolutional anvil grasper for laparoendoscopic surgery for intracorporeal circular stapled anastomosis during laparoscopic colorectal surgery.

Traditional anvil graspers cannot delicately handle the anvil head as a result of their unique jaw shape that enhances grip force, and they are not suitable for confined pelvic space. With a manufacturing company, we developed a novel anvil grasper, the evolutional anvil grasper for laparoendoscopic surgery (EAGLE), to ensure more precise and safer anastomosis procedures. The EAGLE has curved blades that create a 6‐mm grasping surface that is the same diameter as the anvil stem and is covered with tungsten carbide tips. When using the EAGLE, a surgeon grasps the anvil stem slightly and easily, handles the anvil head and proximal colon, and smoothly sets the anvil to the center rod of the circular stapler. A surgeon can also securely grasp the stem of the anvil, push it into the center rod of the circular stapler and then perform a sequence of actions in anastomosis procedures smoothly and safely.