Biomedical subjects

C K Tai

Publications and source records attributed to C K Tai.

5 recordsLinked to original sources

PubMed2005

Laparoscopy versus open left lateral segmentectomy for recurrent pyogenic cholangitis.

BACKGROUND: Recurrent pyogenic cholangitis (RPC) is a common disease in Southeast Asia. Its classical presentation is repeated attacks of cholangitis with multiple recurrences of bile duct stones. The stones are commonly located in the left lateral segments (2 and 3) and therefore complete clearance is difficult to achieve by either endoscopic retrograde cholangiopancreatography or surgical exploration of the common bile duct. The definitive treatment usually involves resection of the stone-harboring segments. The recent advent in laparoscopic surgery has shown that hand-assisted laparoscopic segmentectomy is a safe and feasible, alternative. This study aimed to compare hand-assisted laparoscopic segmentectomy with open segmentectomy in patients with recurrent, RPC. METHODS: This study retrospectively reviewed a prospectively maintained database of both open and laparoscopic treatments for RPC in a single center between 1994 and 2004. During this period, patients with RPC and left intrahepatic (segments 2 and 3) ductal stones not amendable to endoscopic treatment were recruited for analysis. Patients with concomitant gallbladder stones and common bile duct stones were offered left lateral segmentectomy with cholecystectomy and exploration of the common bile duct. Selected patients would have choledochoduodenostomy drainage during the same operation. The operations were performed via either the hand-assisted laparoscopic approach or the open approach using an ultrasonic surgical aspirator. The two cohorts were compared with respect to perioperative parameters to determine whether there would be any advantage in attempting hand-assisted laparoscopic segmentectomy. RESULTS: During the study period from 1994 to 2004, 17 patients underwent left lateral segmentectomy for RPC. Of the 17 patients, 10 had hand-assisted laparoscopic resections, and 7 underwent open resections. All open resections were performed before 1999. Despite the small number of patients and potential type 2 error, there were no differences in age, sex distribution, number of cholangitic attacks, sessions of endoscopic retrograde cholangiopancreatography before surgery, or number of previous operation between the two groups. The median operating time was shorter in the open group (232.5 vs 150 min; p = 0.007), whereas the median blood loss was similar (350 vs 400 ml; p = 0.551). The median postoperative stay was 8 days for hand-assisted laparoscopic group versus 14 days for the open group. This difference was statistically significant (p = 0.019). There was one open conversion in the hand-assisted laparoscopic group because of intraoperative bleeding from the left hepatic vein. Postoperative complication rates were lower in hand-assisted laparoscopic group, but the difference was not statistically significant (20% vs 57%; p = 126). The intramuscular pethidine requirement again was less in hand-assisted laparoscopic group (0 vs 600 mg; p = 0.002). There was no operative mortality in either group of patients. No recurrent cholangitis was noted in either groups during the median follow-up period of more than 3 years. CONCLUSION: This study not only confirmed the feasibility of hand-assisted laparoscopic segmentectomy for recurrent pyogenic cholangitis, but also showed that this treatment approach is associated with less pain and shorter hospital stay. However, hand-assisted laparoscopic segmentectomy is a lengthier operation and technically more challenging. Nevertheless, the authors believe that with more experience and further improvement of ancillary technology, this procedure can become a standard treatment for recurrent pyogenic cholangitis in selected cases.

Adult↗

PubMed2004

Laparoscopic exploration of common bile duct in difficult choledocholithiasis.

BACKGROUND: This review investigated the role played by laparoscopic exploration of the common bile duct (LECBD) in the management of difficult choledocholithiasis. METHODS: This retrospective study reviewed a prospective database of LECBD for difficult choledocholithiasis during the period 1995 to 2003. RESULTS: Of the 97 LECBDs performed in the authors' center from 1995 to 2003, 25 were performed for difficult choledocholithiasis. Difficult choledocholithiasis was defined as failure of endoscopic stone retrieval for the following reasons: access and cannulation difficulty, the difficult nature of common bile duct (CBD) stones, and the presence of endoscopic retrograde cholangiopancreatography (ERCP)-related complications. There were seven unsuccessful cannulations because of previous gastrectomy (n = 5) and periampullary diverticulum (n = 2). Among the 18 patients with failed endoscopic extraction, there were 10 impacted stones, 2 incomplete stone clearances after multiple attempts, 2 type 2 Mirizzi syndromes, 1 proximal stent migration, 1 repeated post-ERCP pancreatitis, 1 situs inversus, and 1 stricture at the distal common bile duct. There were 14 male and 11 female patients with a mean age of 67.8 +/- 15 years. Initial presentations included cholangitis (n = 14, 56%), biliary colic (n = 3, 12%), jaundice/deranged liver function ( n = 5, 20%), cholecystitis (n = 2, 8%), and pancreatitis (n = 1, 4%). Regarding the approach for LECBD, there were 2 transcystic duct explorations and 23 choledochotomies. The mean operative time was 149.4 +/- 49.3 min, and there were three conversions (12%). The stone clearance rate was 100%, and no recurrence was detected during a mean follow-up period of 16.8 months. Five complications were encountered, which included bile leak (3 patients) and wound infection (2 patients). When the results were compared with the remaining 72 LECBDs for nondifficult stones during the same period, the complication rate, conversion rate, and rate of residual stones were similar despite a longer operation time (149.4 +/- 49.4 min vs 121.6 +/- 50.5 min). CONCLUSION: When ERCP is impossible or stone retrieval is incomplete, LECBD is the solution to difficult CBD stones.

Adult↗

PubMed2001

A uniquely stable replication-competent retrovirus vector achieves efficient gene delivery in vitro and in solid tumors.

A major obstacle in cancer gene therapy is the limited efficiency of in vivo gene transfer by replication-defective retrovirus vectors in current use. One strategy for circumventing this difficulty would be to use vectors capable of replication within tumor tissues. We have developed a replication-competent retrovirus (RCR) vector derived from murine leukemia virus (MuLV). This vector utilizes a unique design strategy in which an internal ribosome entry site-transgene cassette is positioned between the env gene and the 3' long terminal repeat (LTR). The ability of this vector to replicate and transmit a transgene was examined in culture and in a solid tumor model in vivo. The RCR vector exhibited replication kinetics similar to those of wildtype MuLV and mediated efficient delivery of the transgene throughout an entire population of cells in culture after an initial inoculation with 1 plaque-forming unit (PFU) of vector per 2000 cells. After injection of 6 x 10(3) PFU of vector into established subcutaneous tumors, highly efficient spread of the transgene was observed over a period of 7 weeks, in some cases resulting in spread of the transgene throughout the entire tumor. MuLV-based RCR vectors show significant advantages over standard replication-defective vectors in efficiency of gene delivery both in culture and in vivo. This represents the first example of the use of an RCR vector in an adult mammalian host, and their first application to transduction of solid tumors.

3T3 Cells↗

PubMed2001

Genomic stability of murine leukemia viruses containing insertions at the Env-3' untranslated region boundary.

Retroviruses containing inserts of exogenous sequences frequently eliminate the inserted sequences upon spread in susceptible cells. We have constructed replication-competent murine leukemia virus (MLV) vectors containing internal ribosome entry site (IRES)-transgene cassettes at the env-3' untranslated region boundary in order to examine the effects of insert sequence and size on the loss of inserts during viral replication. A virus containing an insertion of 1.6 kb replicated with greatly attenuated kinetics relative to wild-type virus and lost the inserted sequences in a single infection cycle. In contrast, MLVs containing inserts of 1.15 to 1.30 kb replicated with kinetics only slightly attenuated compared to wild-type MLV and exhibited much greater stability, maintaining their genomic integrity over multiple serial infection cycles. Eventually, multiple species of deletion mutants were detected simultaneously in later infection cycles; once detected, these variants rapidly dominated the population and thereafter appeared to be maintained at a relative equilibrium. Sequence analysis of these variants identified preferred sites of recombination in the parental viruses, including both short direct repeats and inverted repeats. One instance of insert deletion through recombination with an endogenous retrovirus was also observed. When specific sequences involved in these recombination events were eliminated, deletion variants still arose with the same kinetics upon virus passage and by apparently similar mechanisms, although at different locations in the vectors. Our results suggest that while lengthened, insert-containing genomes can be maintained over multiple replication cycles, preferential deletions resulting in loss of the inserted sequences confer a strong selective advantage.

3' Untranslated Regions↗

PubMedDate not supplied

Antegrade biliary stenting versus T-tube drainage after laparoscopic choledochotomy--a comparative cohort study.

BACKGROUND/AIMS: Laparoscopic exploration of the common bile duct (LECBD) has been proven to be an effective and preferred treatment approach for uncomplicated common bile duct stones. However there is still controversy regarding the choice of biliary decompression after laparoscopic choledochotomy. METHODOLOGY: This is a retrospective comparison between the use of antegrade biliary stenting and T-tube drainage following successful laparoscopic choledochotomy. During the period between January 1995 and July 2003, biliary decompression was achieved by either antegrade biliary stenting or T-tube drainage based on the discretion of the operating surgeon. For antegrade biliary stenting, a 10-Fr Cotton-Leung biliary stent was inserted through the choledochotomy and passed down across the papilla. The stent position was confirmed by on-table choledochoscopy before interrupted single-layered closure of the common bile duct. Endoscopic retrograde cholangiopancreatography (ERCP) was performed to remove the stent 4 weeks after operation and at the same time to check for any residual stones or other complications like stricture or leak. In the T-tube group, a 16-Fr latex T-tube was used and the long limb was brought out through the subcostal trocar port followed by the same method of bile duct closure. Cholangiogram through the T-tube was performed on day 7 and the tube would be taken off 1 week later (about 2 weeks after operation) if the cholangiogram did not reveal any abnormality. The two groups were compared according to the demographic data, operation time, length of hospital stay and complication rates. RESULTS: During the study period, 108 laparoscopic explorations of the common bile duct were performed in our centre of which 95 were attempted laparoscopic choledochotomies and 13 were transcystic duct explorations. Of the 95 patients with attempted laparoscopic choledochotomy, there were 9 open conversions, 17 laparoscopic bilioenteric bypasses and 6 primary closures of the common bile duct. All of these patients together with those receiving transcystic duct explorations were excluded and the remaining 63 patients having postoperative bile diversion by either antegrade biliary stenting or T-tube drainage were included in this study. Bile diversion was achieved by antegrade biliary stenting in 35 patients whereas 28 patients had T-tube drainage. There was no difference between the two groups in terms of age, clinical presentation, bilirubin level, length of hospital stay, follow-up duration, common bile duct size, size of common bile duct stones, incidence of residual/recurrent stone and complication rate. It was observed that more patients in the stenting group developed bile leak (14.2% vs. 3.5%) and required more intramuscular pethidine injections (182.86 +/- 139.30 vs. 92.81+/-81.15mg, P=0.000). On the other hand, the T-tube group had longer operation time (141.4+/-45.1 vs. 11 1.1+/-33.9 minutes, P=0.006) and had a longer postoperative hospital stay (10.0+/-7.4 vs. 8.8+/-9.3 days, P=0.020) reaching statistical significance. CONCLUSIONS: Postoperative bile diversion by antegrade biliary stenting after laparoscopic choledochotomy is shown to shorten operation duration and postoperative stay as compared to T-tube drainage, but the problem of bile leak needs further refinement of insertion technique.

Aged↗