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Christopher Lawrence

Publications and source records attributed to Christopher Lawrence.

14 recordsLinked to original sources
PubMed2006

Success and complications of endoscopic removal of giant duodenal and ampullary polyps: a comparative series.

BACKGROUND: Increasing reports suggest that endoscopic removal of benign ampullary and duodenal polyps is safe and frequently definitive; however, most reported polyps have been small in size (<3 cm). We have developed experience with endoscopic removal of increasingly large and complex polyps. PATIENTS: Fifty-one cases of endoscopic removal were attempted and grouped according to size: group A (n = 22) polyps 1 to 3 cm and group B (n = 29) polyps 3 cm or larger, including 7 cases larger than 5 cm. When the ampulla was involved, biductal sphincterotomy and prophylactic pancreatic duct stent placement was performed first, followed by saline solution-assisted piecemeal polypectomy, argon plasma coagulation, selective endoclip placement, and recovery of all polyp fragments. INTERVENTIONS: Endoscopic removal of duodenal and ampullary adenomas. RESULTS: The outcomes of small and large adenoma removal include mean number of endoscopic retrograde cholangiopancreatographies required for complete removal (2.09 vs 2.56, P = .392), number of complications (4.5% vs 13.9%, P = .375), discovery of unsuspected cancer (0% vs 10.3%, P = .242), and final definitive resolution (100% vs 86.2%, P = .124). Complete removal was achieved in 92.2% of all patients. LIMITATIONS: This was a single center retrospective study. CONCLUSIONS: Large (>/=3 cm) ampullary and duodenal polyps comprised 56.9% of our endoscopically treated cases and present special challenges to definitive endoscopic removal. Successful removal of even very large sessile lesions is possible with minimal increase in risk.

Adult↗
PubMed2006

Five years of steroid sparing in renal transplantation with tacrolimus and mycophenolate mofetil.

Steroid sparing with tacrolimus and mycophenolate mofetil (MMF) is associated with good short-term renal transplant outcomes. However, late allograft dysfunction and failure remain concerns. In this study, 101 consecutive patients underwent renal transplantation with tacrolimus, MMF, and 7 days of corticosteroids only. After a median follow-up of 51 months (range 36-62), overall patient survival is 97%, and overall survival with graft function is 91%. The acute rejection rate at 12 months was 19%. Late rejection was uncommon, with only three further episodes beyond 12 months. Graft function was stable during the study, with a mean creatinine of 140 micromol/L and mean estimated creatinine clearance of 57 ml/min at the end of follow-up. Six patients developed posttransplant diabetes mellitus (three cases beyond 12 months). This steroid avoidance regimen is associated with excellent medium-term patient and graft outcomes, and a low incidence of side effects.

Adult↗
PubMed2006

Testing excision models for responses of mismatch-repair systems to UV photoproducts in DNA.

Mismatch-repair (MMR) systems correct DNA replication errors and respond to a variety of DNA lesions. Previous observations that MMR antagonizes UV mutagenesis, and that the mismatch-recognition protein heterodimer MSH2*MSH6 (MutSalpha) selectively binds DNA containing "mismatched" photoproducts (T[CPD]T/AG, T[6-4]T/AG) but not "matched" photoproducts (T[CPD]T/AA, T[6-4]T/AA), suggested that mismatched photoproducts would provoke MMR excision similar to mismatched bases. Excision of incorrect nucleotides inserted opposite template photoproducts might then prevent UV-induced mutation. We tested T[CPD]T/AG DNA, in a sequence context in which it is bound substantially by hMutSalpha and in three other contexts, for stimulation of 3' MMR excision in mammalian nuclear extracts. T[CPD]T/AG was inactive in HeLa extracts, or in extracts deficient in the photoproduct-binding proteins DDB or XPC* hHR23B, arguing against interference from the nucleotide excision repair pathway. Prior incubation with hMutSalpha and MLH2.PMS2 (hMutLalpha) did not increase excision relative to homoduplex controls. T[6-4]T/AG also failed to provoke excision. T/G, C/A, and T/T substrates, even though bound by hMutSalpha no better than T[CPD]T/AG substrates, efficiently provoked excision. Even a substrate containing three T[CPD]T/AG photoproducts (in different contexts) did not significantly provoke excision. Thus, MMR may suppress UV mutagenesis by non-excisive mechanisms.

Animals↗
PubMed2006

Delayed pancreaticoduodenectomy for cancer patients with prior ERCP-placed, nonforeshortening, self-expanding metal stents: a positive outcome.

BACKGROUND: Self-expanding metal stents (SEMS) inserted for malignant biliary obstruction are felt to be contraindicated in patients with resectable disease. Anecdotally, we observed a number of "unresectable" patients eventually undergoing a "delayed" pancreaticoduodenectomy after additional surgical opinions. This has not been previously described in the literature. OBJECTIVE: To quantitate the frequency with which patients diagnosed with unresectable pancreaticobiliary malignancy (and hence undergoing SEMS placement) eventually undergo Whipple's resection, and to report on the outcomes in these patients. DESIGN AND SETTING: This retrospective, observational study was conducted at a single tertiary care medical center. PATIENTS AND INTERVENTIONS: One hundred consecutive patients who underwent non-foreshortening SEMS placement for presumed unresectable pancreaticobiliary malignancy were identified from our ERCP database. The clinical course and any subsequent operative interventions were reviewed. RESULTS: Despite apparent unresectability, 13 of 100 patients underwent delayed surgical exploration for an attempt at resection. Whipple's resection was successfully performed in 5 patients. No interference with the biliary anastomosis was noted. No unresectable patient required surgical biliary bypass because of the presence of the stent. No pre- or postoperative infections occurred. CONCLUSIONS: Non-foreshortening metal stents can be precisely positioned below the line of any potential surgical transection. The lower risk of preoperative metal stent occlusion, compared to plastic stents, minimizes the risk of postoperative infection. At surgery, unresectable patients do not require unnecessary biliary bypass if a properly positioned SEMS is in place. Properly placed non-foreshortening biliary metal stents are not a contraindication to delayed attempts at Whipple's resection and may be beneficial.

Adenocarcinoma↗
PubMed2006

The shaping of things to come: Scottish medical education 1700-1939.

HISTORICAL BACKGROUND: The history of medical education in Scotland is quite well known. It is largely told as a story of universities, of high standards and of an education mainly available to men from ordinary backgrounds who became general practitioners and servants of the British Empire. This paper asks whether there was anything peculiarly Scottish about the medical education to be had north of the border. DISCUSSION: The answer to this is yes. The paper shows there was a commitment among Scottish teachers to present medicine as a practical art based on general principles that brought the subject together in all its aspects, notably uniting internal medicine and surgery. CONCLUSION: Modern academic medicine has ironed out these differences and medical education in Scotland today is much the same as western medical education in excellent universities anywhere in the world.

Anatomy↗
PubMed2005

Gangrene.

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Gangrene↗
PubMed2005

An update on the role of translesion synthesis DNA polymerases in Ig hypermutation.

Several years have passed since the discovery of activation-induced cytosine deaminase (AID), the molecule responsible for triggering hypermutation of Ig genes. We now know that AID deaminates cytosines in the DNA encoding the variable portion of the Ig receptor, although an additional role in deaminating a regulatory mRNA transcript has not been ruled out. A major question that remains unanswered is how AID, a cytosine deaminase, causes mutations at both G:C and A:T base pairs. Mounting evidence suggests the involvement of a group of error-prone DNA polymerases known to bypass DNA lesions: the translesion synthesis (TLS) DNA polymerases. In this Review, we discuss the evidence for a role of TLS DNA polymerases in Ig hypermutation and argue that a major remaining challenge in our understanding of this mechanism is the recruitment of TLS DNA polymerases to the Ig locus following AID-mediated cytosine deamination.

Animals↗
PubMed2004

Clinic.

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Clinical Medicine↗
PubMed2003

Mapping the kinase domain of Janus Kinase 3.

The utilization and impact of parallel synthesis on lead exploration around initial hit oxindole (1) are described. The emergent SAR, analogue design and functional impact will also be detailed.

Adjuvants, Immunologic↗
PubMedDate not supplied

Pathology.

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History, 16th Century↗