Variation in amount of wild-type transthyretin in different fibril and tissue types in ATTR amyloidosis

Familial transthyretin (TTR) amyloidosis is caused by a mutation in the TTR gene, although wild-type (wt) TTR is also incorporated into the amyloid fibrils. Liver transplantation (LT) is the prevailing treatment of the disease and is performed in order to eliminate the mutant TTR from plasma. The outcome of the procedure is varied; especially problematic is a progressive cardiomyopathy seen in some patients, presumably caused by continued incorporation of wtTTR. What determines the discrepancy in outcome is not clear. We have previously shown that two structurally distinct amyloid fibrils (with or without fragmented ATTR) are found among ATTRV30M patients. In this study, we investigated the proportion of wtATTR in cardiac and adipose amyloid from patients having either fibril type. It was found that cardiac amyloid more easily incorporates wtTTR than adipose amyloid, offering a potential explanation for the vulnerability of cardiac tissue for continued amyloidosis after LT. In cardiac tissue, fibrils with fragmented ATTR contained a higher wt proportion than fibrils without, suggesting that continued incorporation of wtTTR after LT, perhaps, can take place more easily in these patients. In adipose tissue, a rapid increase in wt proportion after LT indicates that a rather fast turnover of the deposits must occur. A difference in wt proportion between the fibril types was seen post-LT but not pre-LT, possibly caused by differences in turnover rate. Conclusively, this study further establishes the basic dissimilarities between the two fibril types and demonstrates that their role in LT outcome needs to be further investigated

Validation of a Novel Virtual Reality Simulator for Robotic Surgery

Objective. With the increase in robotic-assisted laparoscopic surgery there is a concomitant rising demand for training methods. The objective was to establish face and construct validity of a novel virtual reality simulator (dV-Trainer, Mimic Technologies, Seattle, WA) for the use in training of robot-assisted surgery. Methods. A comparative cohort study was performed. Participants (n=42) were divided into three groups according to their robotic experience. To determine construct validity, participants performed three different exercises twice. Performance parameters were measured. To determine face validity, participants filled in a questionnaire after completion of the exercises. Results. Experts outperformed novices in most of the measured parameters. The most discriminative parameters were “time to complete” and “economy of motion” (P<0.001). The training capacity of the simulator was rated 4.6 ± 0.5 SD on a 5-point Likert scale. The realism of the simulator in general, visual graphics, movements of instruments, interaction with objects, and the depth perception were all rated as being realistic. The simulator is considered to be a very useful training tool for residents and medical specialist starting with robotic surgery. Conclusions. Face and construct validity for the dV-Trainer could be established. The virtual reality simulator is a useful tool for training robotic surgery

Endoscopic sphincterotomy for bile duct calculi: factors influencing the success rate. Hepato-Gastroenterol 1996; 43: 127-133.

BACKGROUND/AIMS: Endoscopic sphincterotomy is an established treatment of retained or recurrent common bile duct calculi after cholecystectomy and in the majority of patients with an intact gallbladder. In order to identify patients ultimately requiring additional endoscopic procedures or surgery, factors predictive of decreased endoscopic bile duct clearance were sought. MATERIAL AND METHODS: Between 1981 and 1992 endoscopic sphincterotomy was performed in 393 consecutive patients with either intact gallbladders (n = 246), recurrent (n = 92) or retained (n = 55) calculi. RESULTS: There was a 9.4% overall early complication rate for the procedure and a 30-day mortality rate of 0.5% (two patients, non-procedure related). Complete removal of all bile duct calculi failed in 35/393 patients (8.9%). In patients with intact gallbladder the clearance rate at first attempt was higher (p = 0.002; Chi-square test) in the presence of solitary as compared to multiple stones. The same was found in patients with recurrent stones as well (p < 0.001). In non-cholecystectomized patients with single or multiple stones smaller than 10 mm, the clearance rate was higher at first (p = 0.02) as well as at final (p < 0.002) attempt as compared to patients with larger stones. Single small ( < 10 mm) compared to single large stones in patients with intact gallbladder had a higher clearance rate at final (p = 0.002) but not at first (p = 0.18) attempt. Patients with intact gallbladder and pancreatitis had higher clearance rate at first attempt compared to patients with jaundice (p = 0.001) or patients without concomitant pancreatobiliary disease (p = 0.002). Clearance rate was the same in patients with and without endoscopic sphincterotomy complications, except for patients with basket impaction, in whom the clearance rate was decreased (p = 0.02). CONCLUSIONS: Thus, in patients with intact gallbladder surgery should be considered after failed complete bile duct clearance at first attempt