Tokuro Kunieda

Pathophysiology of aganglionic colon and anorectum: An experimental study on aganglionosis produced by a new method in the rat

• Aganglionosis was produced in the rat by applying 0.1% benzalkonium solution for 30 min to the outer surface of the descending colon and the anorectum of a 1 cm long segment. This method was named the experimental anganglionosis-producing procedure or EAPP method. By this method, the aganglionic portion was found to be narrowed and the proximal segment become dilated as in megacolon. When the chemical was applied to a segment 3cm long or more, the animals succumbed. The portion treated with this method was confirmed to be dener-vated by Nissl stain, Bodian stain, supervital methylene blue stain, acetylcholinesterase stain and catecholamine fluorescence method. In the aganglionic colon produced by EAPP, the normal inhibitory reaction responding to different stimulations (intraluminal balloon inflation, electrical stimulation, or mechanical stimulation by pinching) to the proximal segment was found to be abolished. In the aganglionic anorectal segment produced by EAPP, the normal inhibitory reaction, recorded at the level of the internal sphincter muscle, to stimluations same as described above (i.e., the reaction similar to the recto-sphincteric reflex) was found to be abolished. The aganglionic segment produced by EAPP was confirmed to be functionally denervated and to have functionally intact smooth muscles by the fact that the segment examined in vitro was unresponsive to physostigmine but responsive to barium chloride showing normal contraction waves. The results of present study lend support to the assumption that aperistalsis observed in an aganglionic intestinal segment is caused by defect of intramural nerve plexi.

Selective destruction of intestinal nervous elements by local application of benzalkonium solution in the rat

Intestinal aganglionosis produced by serosal application of 0.1% benzalkonium solution to the colon of the rat was studied electronmicroscopically, and its was concluded that a higher susceptibility to the agent and a lower recovering ability of the nerve elements might be responsible for the phenomenon.

Late appearance of resistance to tumor rechallenge following cryosurgery: A study in an experimental mammary tumor of the rat

Abstract Resistance to tumor challenge following surgical and cryosurgical eradication of the tumor was studied, using an experimental mammary tumor of the rat, MRMT-1. It was revealed that rejection rate of the challenged tumor increased gradually following cryosurgery and reached its peak at 10 weeks after cryosurgery. No such phenomenon was observed after surgical excision of the tumor. Decreased incidence of lymph node metastases and decreased tumor weights in “take” cases also suggested an increased immunological activity against the tumor at 10 weeks after cryosurgery.

Antitumor immunologic reactivity in the relatively early period after cryosurgery: experimental studies in the rat.

Abstract An experimental investigation was performed on antitumor immunity in the relatively early postoperative period after cryosurgery, using a metastasizing rats mammary tumor, MRMT-1. Two weeks after its inoculation, surgical excision of the tumor, cryosurgery, surgical excision plus inoculation with freezing-thawing produced vaccine, or surgical excision plus fasting for 72 hr was performed, and postoperative follow-up was done on incidences of metastases, those of metastatic death, etc. Specific immunologic reactivity was examined in the surgical excision (SE) and cryosurgery (CR) groups. The FTV and fasting groups showed more metastatic deaths as compared with the SE group. The CR and SE groups did not differ significantly from each other in incidences of lung and lymph node metastases. Specific footpad reactivity at 2 and 3 weeks after treatment was lower in the CR group than in the SE group. Winns neutralization assay showed an inhibition of tumor growth at 1 and 3 week(s) after treatment both in the SE and in the CR groups, the inhibitory effect tending to be lower in the latter. Inactivated serum obtained at 1 week after treatment showed a facilitation of tumor growth in the SE group and a tendency of tumor suppression in the CR group, showing a significant difference between them. A mild reduction in antitumor immunity seen in the relatively early postoperative period following cryosurgery probably was not due to a blocking effect by superfluous antigens. Rather it was considered to be due to activation of suppressor cells, consequent on cryosurgical stress, and/or slow and steady absorption of antigens.

Facilitation of Tumor Metastasis by Operative Stress and Participation of Cell-Mediated Immunity

5-week-old syngeneic female SD rats were inoculated subcutaneously at the dorsal flank with 200 mg of a metastasizing rats mammary tumor, MRMT-1. A significantly higher incidence of lung metastasis was observed in the cases in which tumor excision on day 14 was accompanied by 30 min laparotomy than in the cases of simple tumor excision. PHA lymphoblastogenesis on day 17 was significantly lower in the cases of tumor excision plus laparotomy on day 14 than in the cases of simple tumor excision. Winns assay using splenocytes revealed a postoperative enhanced suppressor activity in the cases undergoing laparotomy stress. Possible participation of the raised suppressor activity to facilitation of metastasis was discussed.

Stress ulcer accompanying subarachnoid hemorrhage—A new rat model

New rat model of stress ulcer, related to subarachnoid hemorrhage (SAH) was devised. A 0.2 ml of the arterial blood, obtained from another rat of the same litter, was injected into the cisterna magna and 4 days later, mild stress, consisting of restraint plus water-immersion for 3 hours to the injected rat, produced gastric ulcers. These lesions were far more marked than in usual rats undergoing the same stress (P<0.001). Using this “SAH-stress model”, effects of various counteracting measures were examined. Based on the results, we concluded that SAH produced a hypersensitivity or an abnormal exitability of the autonomic nervous centers, and the relatively mild stress effectively weakened the gastric defensive factors and strengthened the gastric aggressive factors, thus resulting in ulcer formation.

Experimental studies on intestinal absorption following Martin's operation

Experimental studies were done on rats on compensatory absorptive capacity following Martins operation for extensive aganglionosis. Experimental aganglionosis was produced in the descending colon of rats by serosal application of 0.1% benzalkonium chloride solution. Wide side-toside anastomosis was performed between the aganglionic colon and the distal ileum, removing the remaining colon. As to absorptive capacity of water and electrolytes, this experimental intestine was compared, with other intestines, especially control intestine, in which similar side-to-side anastomosis was done between the normal colon and the normal ileum. “Experimental” as well as control intestine showed higher absorptive capacities of water, Na and Cl per unit length than did summed up values of the ileum and the colon per unit length. Postoperative body weight curves showed fairly good increases and appearance of feces showed a fair improvement in the experimental group. Autopsy of experimental intestine revealed marked dilatation of the anastomosed ileum and mucosal hypertrophy of the anastomosed colon. These results suggested a favorable compensatory absorptive capacity following Martins operation.

On the pathogenesis of intestinal aganglionosis. A consideration based on electron microscopic observations of experimental and clinical aganglionoses

A close resemblance in fine structure was observed between the aganglionic colon, produced in rats by serosal application of 0.1% benzalkonium chloride solution, and the aganglionic descending colon, or more proximal segments, of Hirschsprungs disease. The pathogenesis of the disease is discussed.

On the pathway of the rectosphincteric reflex.

In several rat models, including those with circular and semicircular rectal aganglionosis, the rectosphincteric reflex was examined. The reflex was confirmed to be essentially an intramural one and its route is considered to run mainly in the longitudinal and partly in the oblique directions.