Biomedical subjects

O Ike

Publications and source records attributed to O Ike.

39 records · Page 3Linked to original sources

PubMedDate not supplied

Experimental studies on an artificial esophagus for the purpose of neoesophageal epithelization using a collagen-coated silicone tube.

An artificial esophagus was fabricated from a collagen-coated silicone tube 5 cm long, with an inner diameter of 2.5 cm and a wall thickness of 1 mm. The outer surface was coated with dry collagen to 5 mm thickness. The bilayered prosthesis was anastomosed to the cervical esophagus of adult mongrel dogs that were fed only by intravenous hyperalimentation (IVH) with 80 cal/kg/day and 60 ml water/kg/day for 3 weeks after the operation. Once the dogs began to consume food orally, the artificial esophagus dropped spontaneously into the stomach and formation of the neoesophagus was complete. Macroscopically, the neoesophagus showed no evidence of leakage or inflammation and had a smooth internal surface, but it developed slight segmental narrowing. Microscopically, layers of stratified squamous epithelium covered the neoesophagus within 3 to 4 weeks. The most characteristic feature of the artificial esophagus was that the replacement prosthesis did not remain in the esophagus after healing. Esophageal epithelization extended into the collagen layer coating the silicone tube and a new esophageal lumen was regenerated, thereby decreasing the chance of infection and leakage. However, neoesophageal stenosis was observed when the silicone tube was removed.

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PubMedDate not supplied

Experimental studies on an artificial trachea of collagen-coated poly(L-lactic acid) mesh or unwoven cloth combined with a periosteal graft.

Artificial tracheas were fabricated from poly(L-lactic acid) mesh or unwoven cloth coated with collagen in order to reconstruct the respiratory airway by self regeneration without retaining the prosthesis at the replacement site, thus preventing infection, air leakage, granulation tissue formation, and displacement of the prosthesis. Nine weeks after placing a periosteal autologous graft from the tibia around the cervical trachea of a rabbit, bone rings formed without infection. Two weeks after replacement of an 8 X 8 mm window-shaped section of the cervical trachea with autologous periosteum, the internal surface of the trachea was well epithelialized without local complications, but ossification was not seen. One week after cervical substitution with our 2 cm long artificial trachea combined with the periosteal graft, cartilage was produced around the mesh material but neither ossification nor epithelization was observed thereafter, probably due to local infection. On the other hand, cartilage, bone, and epithelium did not form around the unwoven cloth artificial trachea after the substitution, probably because of severe infection due to collapse of the tracheal lumen. However, the formation of bone rings around the trachea suggests preservation of the neotracheal lumen, which may have potential for the treatment of tracheomalacia and/or bronchomalacia.

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PubMedDate not supplied

Experimental studies of a hybrid artificial esophagus combined with autologous mucosal cells.

Preliminary results, obtained using an artificial esophagus combined with autologous mucosal cells in dogs, are reported. The authors' prosthesis is a silicone tube coated with freeze dried collagen sponge. Cells infiltrate this collagen layer and synthesize new tissue, which will become the neoesophagus. The silicone tube imparts rigidity to the prosthesis and prevents infection, leakage, and dislocation of the prosthesis at the anastomotic site. After formation of the epithelized neoesophageal lumen, the silicone tube drops into the stomach as the result of peristalsis in response to food. Eventually, no artificial prosthesis remains in place, and the defect is replaced by ingrowing tissue. This process was shortened by mucosal cell seeding. Before replacement, the authors harvested oral mucosal (OM) cells, cultured them for 10 days, and seeded them in the collagen layer of the prosthesis just after anastomosis. The neo-esophageal lumen was formed 1 week after the operation without any local complications, infection, leakage, or stenosis, and 2 weeks later the firm, epithelized neoesophagus was completed. OM cell seeding accelerated not only epithelization, but also regeneration of mesenchymal tissue. Parallel with this, transmission electron microscopy showed that most of the cells in the neoesophagus exhibited large nuclei and prominent rough endoplasmic reticulum, indicative of active collagen production.

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