Long-term occlusion of the porcine cystic duct by means of endoluminal radio-frequency electrocoagulation

Recurrent cholelithiasis must be expected after gallstone removal without cholecystectomy. Chemical gallbladder ablation may offer prevention but requires preliminary cystic duct occlusion. Radio-frequency (RF) electrocoagulation of the cystic duct was performed in 15 pigs to induce occlusion by a controlled thermal epithelial injury. A flexible coagulation catheter was placed into the cystic duct lumen under fluoroscopic control by means of either subhepatic cholecystostomy or direct, percutaneous transhepatic gallbladder puncture. Complete cystic duct occlusion was proved in 14 animals. Follow-up ranged from 1 to 17 weeks (mean, 11 weeks). Histologically, the RF technique induced an intense chronic inflammatory and fibroblastic reaction, which eventually obliterated the coagulated cystic duct segments. There was no epithelial regeneration or recanalization of the fibrotic cystic duct segments. The adjacent structures, particularly the cystic artery, were intact in all specimens.     

Morphine induced saccharin aversion in α-methyltyrosine pretreated rats

Rats pretreated with l--methyltyrosine (AMT) and then given pairings of saccharin drinking and morphine infusion subsequently showed a reduced preference for saccharin over water, when compared with control rats. Control conditions were AMT pretreatment with saccharin-saline pairings, saline pretreatment with saccharin-morphine pairings, and saline pretreatment with saccharin-saline pairings. A second experiment also showed significantly greater saccharin aversion with morphine-infused, AMT-pretreated rats than with saline-infused, AMT-pretreated rats although the morphine dosage was lower than that used in Experiment 1. These results suggest that morphine is aversive to rats that have been treated with AMT.This research was supported in part by U.S. Public Health Service Grant MH 13570-03.     

Effects of CS-US interval on conditioning of drug response,with assessment of speed of conditioning

Summary Effects of CS-US interval on the development of a conditioned drug response was studied by pairing a 1.5 mg/kg ip d-amphetamine injection (US) with placement of S in a photocell-type locomotor activity cage (CS). Ss injected immediately before and 30 min before placement were significantly more active on saline-injection test days than were Ss injected after removal or 3–4 h later. To test for apparent rapid conditioning of drug response, Ss were given only six pairings with drug injection immediately preceding placement in the apparatus. On saline test day, these Ss were half again more active than controls, which had received saline just before placement and the drug 3–4 h later.This article is based upon a dissertation submitted by the senior author in partial fulfillment of the requirements for the Ph. D. degree at the University of Mississippi. Preparation of this article was supported in part by USPHS Training Grant No. MH-8565 to the University of Minnesota.