Replacement of the pyloric sphincter with the ileocecal valve: an experimental study.

BACKGROUND: Several surgical methods have been devised and applied to overcome the complications associated with the loss of the pyloric sphincter after distal gastrectomy. However, none of these methods creates an efficient sphincteric mechanism at the anastomotic site. The purpose of this experimental study in dogs was to replace the pylorus with the ileocecal valve and determine whether its sphincteric function would be preserved in its new location without affecting gastrointestinal motility and the health of the animals. METHODS: Thirteen dogs underwent surgical removal of the pyloric sphincter and a partial distal gastrectomy. The ileocecal valve, with a short segment of ileum, was then relocated so that the ileal segment was anastomosed to the stomach while the cecal segment was anastomosed to the duodenum. Intestinal continuity was reestablished by anastomosing the distal ileum with the ascending colon. Intraileal and intracolic pressures were measured in all animals prior to and following transposition of the ileocecal valve. In 3 of these animals, pre-pyloric (intragastric) and post-pyloric (intraduodenal) pressures were also measured before the pylorus was removed. Pressure measurements on both sides of the transposed ileocecal valve were performed again 4-6 months later. All pressure measurements were made directly with a water manometer. Radiographic and fluoroscopic studies were carried out on all animals to assess gastrointestinal motility, gastric emptying times, and the sphincteric competence of the transposed ileocecal valve. Hematological and biochemical studies intended to assess the nutritional status of all animals were carried out. Also, postoperative measurements were made of gastric basic acid output. RESULTS: All animals were alive and well 4-6 months after the initial operative procedure. Hematological studies and biochemical tests and studies of liver function remained normal. There was a slight reduction in serum B12 levels and, as expected, a significant postoperative reduction in gastric basic acid output. The intraluminal pressure measurements and the radiographic and fluoroscopic studies all showed that the sphincteric mechanism of the ileocecal valve was preserved in its new location, that gastrointestinal motility was not impaired, and that the healthy condition of the animals was maintained. Gross and histological examination of the transposed segments of the intestinal tract did not reveal any abnormalities. CONCLUSION: Because the anatomy and physiology of the human alimentary tract are similar to those of the dog, this technique may be applicable clinically, when indicated, to avoid and/or relieve complications resulting from gastrectomy, when those complications do not respond or have not responded to conservative management.

Common tumor rejection antigens in methylcholanthrene-induced squamous cell carcinomas of mice detected by tumor protection and a radioisotopic footpad assay.

Seven transplantable lines of squamous cell carcinoma of the skin initiated in BALB/c mice by skin painting with methycholanthrene were systematically tested for cross-reactivity of their tumor rejection antigens in a 7 X 7 matrix. As determined by decreased tumor frequency after tumor cell challenge, each line was immunogenic against and/or immunosensitive to at least one and usually more than one of the other lines. A radioisotopic footpad assay for delayed hypersensitivity against viable tumor cells confirmed the cross-reactivity shown by tumor rejection. More than two antigens appeared to be present in the lines. Tests for C-type viruses were positive in all tumors; those for polyoma virus were negative. Whether the uniform presence of C-type viruses can account for the number and variety of antigens found, or whether the tumor rejection antigens are independent of virus expression, remains an open question. The finding of cross-reacting tumor rejection antigens in methylcholanthrene-induced squamous cell carcinomas encourages prospects for the development of more broadly applicable immunodiagnostic and immunotherapeutic reagents.

Local adoptive transfer of antitumor cellular immunity to xenogeneic animals studied with a rapid radioisotopic footpad assay.

The antitumor cellular immune response to Gross virus-induced rat tumor cells in F344 rats, as measured by a sensitive radioisotopic footpad assay, was adoptively transferred to syngeneic rats and to xenogeneic irradiated BALB/c mice. Xenogeneic transfer was accomplished by the injection of a mixture of rat tumor cells and syngeneic spleen cells, peritoneal exudate cells, or blood lymphocytes from specific immune rats into the footpads of mice. Peritoneal exudate cells produced the strongest footpad reaction in xenogeneic recipients. Use of the xenogeneic adoptive transfer system in a bioassay for human antitumor immunity appeared feasible.

Accelerated regeneration of trypsin-treated surface antigens of simian virus 40-transformed BALB/3T3 cells induced by X-irradiation.

The antigens of SV40-transformed BALB/3T3 cells measured by a radioisotopic footpad assay after removal by trypsin treatment regenerated in vitro in 3 to 6 hr. After X-irradiation with 3000 R, however, the antigens were regenerated to normal levels within 1 h. X-ray doses of between 1000 and 5000 R accelerated the regeneration of cell surface antigens, while X-irradiation with the larger dose of 8000 R did not. X-irradiation of nontrypsinized tumor cells was without effect. Possible mechanisms of this phenomenon are discussed.