Complications of biliary-enteric anastomoses.

INTRODUCTION Biliary-enteric anastomoses are performed for a range of indications and may result in early and late complications. The aim of this study was to assess the risk factors and management of anastomotic leak and stricture following biliary-enteric anastomosis. METHODS A retrospective analysis of the medical records of patients who underwent biliary-enteric anastomoses in a tertiary referral centre between 2000 and 2010 was performed. RESULTS Four hundred and sixty-two biliary-enteric anastomoses were performed. Of these, 347 (75%) were performed for malignant disease. Roux-en-Y hepaticojejunostomy or choledocho-jejunostomy were performed in 440 (95%) patients. Perioperative 30-day mortality was 6.5% (n=30). Seventeen patients had early bile leaks (3.7%) and 17 had late strictures (3.7%) at a median of 12 months. On univariable logistic regression analysis, younger age was a significant risk factor for biliary anastomotic leak. However, on multivariable analysis only biliary reconstruction following biliary injury (odds ratio [OR]=6.84; p=0.002) and anastomosis above the biliary confluence (OR=4.62; p=0.03) were significant. Younger age and biliary reconstruction following injury appeared to be significant risk factors for biliary strictures but multivariable analysis showed that only younger age was significant. CONCLUSIONS Biliary-enteric anastomoses have a low incidence of early and late complications. Biliary reconstruction following injury and a high anastomosis (above the confluence) are significant risk factors for anastomotic leak. Younger patients are significantly more likely to develop an anastomotic stricture over the longer term.

Larger hepatic metastases are more frequent with N0 colorectal tumours and are associated with poor prognosis: implications for surveillance.

BACKGROUND: Surgery is the treatment of choice for colorectal cancer liver metastases (CLM). The aim of our study was to analyze which clinical and pathological risk factors can predict recurrence after liver resection. METHODS: Consecutive patients who underwent hepatic resection for CLM were studied retrospectively to identify risk factors influencing cancer recurrence, by univariate and multivariable analyses. RESULTS: 97 patients (2004-2008) with a median age of 64.6 years (inter-quartile range 57.6-72.6) had a median disease free survival of 16.4 months. On univariate analysis the largest metastasis >5 cm (hazard ratio, HR 2.04, 95% CI 1.10-3.80, p = 0.03), presence of extra-hepatic disease (HR 2.39, 95% CI 1.14-5.02, p = 0.02) and a resection margin ≤5 mm (HR 1.91, 95% CI 1.06-3.47, p = 0.03) were significantly associated with a higher risk of recurrence after curative resection for CLM. These were confirmed as independent predictors for recurrence on multivariable analysis. There were significantly more patients with lymph node negative (N0) primary in the group with liver secondary > 5 cm (n = 18, 39%), than in the group with liver secondary £5 cm (n = 7, 14.6%) (p = 0.01). CONCLUSION: We demonstrated a positive correlation between N0 primary tumour and large liver metastases, which have a higher risk of disease recurrence. If validated in larger, independent studies, this study would suggest routine imaging surveillance follow up of even N0 colorectal tumours, until the biology of these tumours is fully understood.

A comparison of pancreaticoduodenectomy with extended pancreaticoduodenectomy: a meta-analysis of 1909 patients.

AIM: To compare outcomes between pancreaticoduodenectomy (PD) and extended pancreaticoduodenectomy (EPD) from all published comparative studies in the literature. METHODS: Using meta-analytical techniques the present study compared operative details, post-operative adverse events and survival following PD and EPD. Comparative studies published between 1988 and 2005 of PD versus EPD were included. End points were classified into peri-operative details, post-operative complications including 30day mortality, and survival as measured during follow up. A random effect model was employed. RESULTS: Sixteen comparative studies comprising 1909 patients (865 PD and 1044 EPD), including 3 randomized controlled trials with 454 patients (226 PD and 228 EPD) were identified. Tumour size was comparable between the groups (weighted mean difference (WMD) -0.16 cm, p=0.76). Significantly more lymph nodes were harvested from those patients undergoing EPD (WMD p=14 nodes, p< or =0.001). Operative time was longer in EPD (WMD -48.9 min, p<0.001) and there was a trend towards fewer positive resection margins (odds ratio (OR) 1.78, p=0.080). Peri-operative adverse events were similar between the groups with only delayed gastric emptying (OR 0.59, p=0.030) occurring less frequently in the PD group. Peri-operative mortality (OR 1.48, p=0.180) and long-term survival (hazard ratio 0.77, p=0.100) showed a non-significant trend favouring EPD. CONCLUSIONS: EPD is associated with a greater nodal harvest and fewer positive resection margins than PD. However, the risk of delayed gastric emptying is increased and no significant survival benefit has been shown. Better designed, adequately powered studies are required to settle this question.

Impact of hospital volume on outcomes for pancreaticoduodenectomy: a single UK HPB centre experience.

BACKGROUND: High hospital volume has a favorable impact on outcomes for complex procedures including pancreaticoduodenectomy (PD); however, the temporal relationship has not been evaluated in a single centre. AIM: To evaluate the impact of UK cancer outcome guidelines (COG) on outcomes for PD in a single UK HPB specialist centre. PATIENTS AND METHODS: All patients with pancreatic pathologies undergoing surgery at our institution from 1999 to 2006 were identified, of which 140 underwent PD. The annual caseload for PD and corresponding outcomes for length of hospital stay, morbidity, mortality and survival were analysed during the period around the implementation of UK COG with an increase in the surgical workload correlating with catchment's population increase from 1.6 to 3.1 million. RESULTS: Between January 1999 and December 2006, 140 patients underwent a PD (M:F 1.06:1; median age 64 (range 34-84) years). Median hospital stay was 16 days (range 7-318). The 30-day mortality was 2.8%, in-hospital mortality was 6.4% and morbidity was 37.1%. Pancreatic leak/fistula rate was 8.6%. Over the 7-year period, PDs per year increased 5.3 fold from 6 procedures in 1999 to 32 in 2006. Analysis of the data for 1999-2002-(pre-COG) and 2003-2006-(post-COG) showed a trend towards decrease in mortality (from 9.7% to 5.0%, p = 0.448: OR = 2.74 (95% CI, 0.58-12.88); Fisher's exact test) and morbidity (from 41.6% to 35.3%; OR = 1.29 (95% CI, 0.74-3.56); p = 0.565). CONCLUSION: With COG implementation within a single UK pancreatic unit, the PD volume and staffing levels increased with a trend towards decreased morbidity and mortality.

A comparison of pancreaticoduodenectomy with pylorus preserving pancreaticoduodenectomy: a meta-analysis of 2822 patients.

BACKGROUND: The gold-standard for surgical excision of peri-ampullary tumours has not been established despite numerous studies, due to conflicting outcomes. AIM: To consolidate the published evidence and compare outcomes between pancreaticoduodenectomy (PD) and pylorus preserving pancreaticoduodenectomy (PPPD) across all published comparative studies. METHODS: Using meta-analytical techniques the study compared: operative details, post-operative adverse events and survival following PD and PPPD. Comparative studies published between 1986 and 2005 of PD versus PPPD were included. A random effect model was employed, with significance reported at the 5% level. RESULTS: 32 studies comprising 2822 patients (1335 PD and 1487 PPPD), including 5 randomized controlled trials with 421 patients (215 PD and 206 PPPD) were included. Patients undergoing PPPD were found to have smaller tumours (weighted mean difference (WMD) -0.54 cm, p=0.030), although no significant difference in the number of patients with stage III or IV disease existed between the groups (odds ratio, OR 1.55, p=0.320). Decreased operating times (WMD -41.3 min, p=0.010) and fewer blood transfusions (WMD -0.9 units, p<0.001) were observed in the PPPD group. There was no difference in post-operative complications, including pancreatic and biliary leaks or fistulae, between the two groups. It was suggested that peri-operative mortality was decreased in the PPPD group (OR 1.7, p=0.040), and overall survival was better (hazard ratio (HR) 0.66, p=0.02), although this did not remain significant on subgroup analysis. CONCLUSIONS: Both PD and PPPD had similar peri-operative adverse events, however, in overall analysis PPPD has lower mortality and improved long-term patient survival, although this was not reflected in the sub-group analysis.

Metallobleomycin-mediated cleavage of DNA not involving a threading-intercalation mechanism.

The DNA cleavage properties of metallobleomycins conjugated to three solid supports were investigated using plasmid DNA, relaxed covalently closed circular DNA, and linear duplex DNA as substrates. Cleavage of pBR322 and pSP64 plasmid DNAs by Fe(II).BLM A(5)-CPG-C(2) was observed with efficiencies not dissimilar to that obtained using free Fe(II).BLM A(5). Similar results were observed following Fe(II).BLM A(5)-CPG-C(2)-mediated cleavage of a relaxed plasmid, a substrate that lacks ends or negative supercoiling capable of facilitating strand separation. BLMs covalently tethered to solid supports, including Fe(II).BLM A(5)-Sepharose 4B, Fe(II).BLM A(5)-CPG-C(6), and Fe(II).BLM A(5)-CPG-C(2), cleaved a 5'-(32)P end labeled linear DNA duplex with a sequence selectivity identical to that of free Fe(II).BLM A(5); cleavage predominated at 5'-G(82)T(83)-3' and 5'-G(84)T(85)-3'. To verify that these results could also be obtained using other metallobleomycins, supercoiled plasmid DNA and a linear DNA duplex were employed as substrates for Co(III).BLM A(5)-CPG-C(2). Free green Co(III).BLM A(5) was only about 2-fold more efficient than green Co(III).BLM A(5)-CPG-C(2) in effecting DNA cleavage. A similar result was obtained using Cu(II).BLM A(5)-CPG-C(2) + dithiothreitol. In addition, the conjugated Co.BLM A(5) and Cu.BLM A(5) cleaved the linear duplex DNA with a sequence selectivity identical to that of the respective free metalloBLMs. Interestingly, when supercoiled plasmid DNA was used as a substrate, conjugated Fe.BLM A(5) and Co.BLM A(5) were both found to produce Form III DNA in addition to Form II DNA. The formation of Form III DNA by conjugated Fe.BLM A(5) was assessed quantitatively. When corrected for differences in the intrinsic efficiencies of DNA cleavage by conjugated vs free BLMs, conjugated Fe.BLM A(5) was found to produce Form III DNA to about the same extent as the respective free Fe.BLM A(5), arguing that this conjugated BLM can also effect double-strand cleavage of DNA. Although previous evidence supporting DNA intercalation by some metallobleomycins is convincing, the present evidence indicates that threading intercalation is not a requirement for DNA cleavage by Fe(II).BLM A(5), Co(III).BLM A(5), or Cu(I).BLM A(5).

Simultaneous binding of two proteins to opposite sides of a single transfer RNA.

Transfer RNA (tRNA) is a small nucleic acid (typically 76 nucleotides) that forms binary complexes with proteins, such as aminoacyl tRNA synthetases (RS) and Trbp111. The latter is a widely distributed structure-specific tRNA-binding protein that is incorporated into cell signaling molecules. The structure of Trbp111 was modeled onto to the outer, convex side of the L-shaped tRNA. Here we present RNA footprints that are consistent with this model. This binding mode is in contrast to that of tRNA synthetases, which bind to the inside, or concave side, of tRNA. These opposite locations of binding for these two proteins suggest the possibility of a ternary complex. The formation of a tRNA synthetase--tRNA--Trbp111 ternary complex was detected by two independent methods. The results indicate that the tRNA is sandwiched between the two protein molecules. A thermodynamic and functional analysis is consistent with the tRNA retaining its native structure in the ternary complex. These results may have implications for how the translation apparatus is linked to other cellular machinery.

Structurally altered substrates for DNA topoisomerase I. Effects of inclusion of a single 3'-deoxynucleotide within the scissile strand.

A partial DNA duplex containing a high efficiency topoisomerase I cleavage site was substituted singly at each of three sites with 3'-deoxyadenosine. Depending on the site of substitution, the facility of the topoisomerase I-mediated cleavage or ligation reactions was altered. Inclusion of the modified nucleoside at the 5'-end of the acceptor oligonucleotide diminished the rate of religation following substrate cleavage by the enzyme.

DNA duplexes containing 3'-deoxynucleotides as substrates for DNA topoisomerase I cleavage and ligation.

The DNA cleavage-ligation reaction of DNA topoisomerase I was investigated employing synthetic DNA substrates containing 3'-deoxyadenosine or 3'-deoxythymidine at specific sites and acceptor oligonucleotides of different lengths. The modified nucleotides were substituted systematically within the putative enzyme-binding domain and also next to the high efficiency cleavage site to determine the effect of single base changes on enzyme function. Depending on the site of substitution, the facility of the cleavage and ligation reactions were altered. The bases at positions -1 and -2 on the noncleaved strand were found to be important for determining the site of cleavage. Inclusion of 3'-deoxythymidine in the scissile strand at position -1 permitted the demonstration that topoisomerase I can cleave and form a 2' --> 5'-phosphodiester linkage. Partial duplexes doubly modified at positions -4 or -6 in the noncleaved strand and at positions +1 or -1 within scissile strand were not good substrates for topoisomerase I, showing that cleavage can depend importantly on binding interactions based on structural alterations at spatially separated sites. Substitution of a 3'-deoxynucleotide on the scissile strand at position -6 enhanced formation of the ligation product resulting from cleavage at site 1 and suppressed cleavage at site 2.

Fe.bleomycin as a probe of RNA conformation.

Two crystallographically defined tRNAs, yeast tRNAAsp and tRNAPhe, were used as substrates for oxidative cleavage by Fe.bleomycin to facilitate definition at high resolution of the structural elements in RNAs conducive to bleomycin binding and cleavage. Yeast tRNAAsp underwent cleavage at G45 and U66; yeast tRNAPhe was cleaved at four sites, namely G19, A31, U52 and A66. Only two of these six sites involved oxidative cleavage of a 5'-G.Pyr-3' sequence, but three sites were at the junction between single- and double-stranded regions of the RNA, consistent with a binding model in which the bithiazole + C-terminal substituent of bleomycin bind to minor groove structures on the RNA. Also studied were four tRNA transcripts believed on the basis of biochemical and chemical mapping experiments to share structural elements in common with the mature tRNAs. Cleavage of these tRNAs by Fe.bleomycin gave patterns of cleavage very different from each other and than those of the mature tRNAs. This observation suggests strongly that Fe.bleomycin cannot be used for chemical mapping in the same fashion as more classical reagents, such as Pb2+ or dimethyl sulfate. However, the great sensitivity of Fe.bleomycin to changes in nucleic acid structure argues that those species which do show similar patterns of cleavage must be very close in structure.