Recurrent intestinal fistulation after porcine acellular dermal matrix reinforcement in enteric fistula takedown and simultaneous abdominal wall reconstruction.

PURPOSE: Porcine acellular dermal matrix (PADM) has been promoted as a suitable material for the reinforcement of the abdominal wall in Ventral Hernia Working Group (VHWG) Grade 3/4 wounds by Ventral Hernia Working Group et al. (Surgery 148(3):544-548). We describe our experience of, and assess the mechanisms for the failure of PADM (PermacolTM) in intestinal and abdominal wall reconstruction (AWR) for enterocutaneous fistulation (ECF). METHODS: All patients referred to our unit who had PADM used for AWR and ECF were studied from a prospectively maintained database. Follow-up data until 31/12/2018 were analysed. PADM was explanted at further surgery and examined histologically. RESULTS: 13 patients, (median age-58.5 years) underwent AWR with PADM reinforcement. Twelve of these (92%) patients had developed abdominal wall defects (AWD) and ECF following complications of previous surgery. Six patients underwent fistula takedown and AWR with PADM, of which 5(83%) refistulated. Seven patients referred to us had already undergone similar procedures in their referring hospitals and had also refistulated. Median (range) time to fistulation after AWR with PADM was 17 (7-240) days. In all cases, PADM had been used to bridge the defect and placed in direct contact with bowel. At reconstructive surgery for refistulation, PADM was inseparable from multiple segments of small intestine, necessitating extensive bowel resection. Histological examination confirmed that the PADM almost completely integrated with the seromuscular layer of the small intestine. CONCLUSION: PADM may become inseparable from serosa of the human small intestinal serosa when it is left in the abdomen during reconstructive surgery. This technique is associated with recurrent intestinal fistulation and intestinal failure and should be avoided if at all possible.

A prospective audit of early stoma complications in colorectal cancer treatment throughout the Greater Manchester and Cheshire colorectal cancer network.

AIM: The study aimed to identify the incidence of early stoma problems after surgery for colorectal cancer to identify predisposing factors and to assess the effect on discharge from hospital and the greater need for community stoma care. METHOD: A prospective study of 192 patients was carried out over a six-month period in the 13 units of the Greater Manchester and Cheshire Cancer Network. Stoma problems were categorized into fistula, leakage, pancaking, necrosis, retraction, separation, stenosis, skin problems, parastomal hernia, suboptimal stoma site and need for resiting or refashioning. Differences in incidence between units (anonymized) were analysed, and the effect of stoma complications on length of hospital stay and the need for additional community stoma care was determined. RESULTS: One hundred and ninety-two patients with stomas were included, of which 52 (27.1%) were identified as being problematic (range 0-66.7% between units). Significant risk factors included stoma type (colostomy) (P < 0.05), short stoma length (P = 0.006), higher BMI (P = 0.043), emergency surgery (P = 0.002) and lack of preoperative site marking (P < 0.001). Problematic stomas were associated with longer hospital stay (P < 0.001) and increased community care (P < 0.001). CONCLUSION: Stoma type, stoma length, body mass index, emergency surgery and lack of preoperative marking were significant risk factors. Overall complication rates compare favourably with other studies.

Dietary variables associated with DNA N7-methylguanine levels and O6-alkylguanine DNA-alkyltransferase activity in human colorectal mucosa.

Components of human diets may influence the incidence of colorectal adenomas, by modifying exposure or susceptibility to DNA-damaging alkylating agents. To examine this hypothesis, a food frequency questionnaire was used to assess the diet of patients recruited for a case-referent study where biopsies of normal colorectal mucosa were collected during colonoscopy and subsequently analysed for DNA N7-methylguanine (N7-MeG) levels, as an indicator of exposure, and activity of the DNA repair protein O6-alkylguanine DNA-alkyltransferase (MGMT), as an indicator of potential susceptibility. Cases with histologically proven colorectal adenomas (n = 38) were compared with referents (n = 35) free of gastrointestinal neoplasia. The case group consumed significantly more red meat (4.5 versus 3.4 servings/week, P < 0.05), processed meats, (4.7 versus 3.2 servings/week, P < 0.05) and % food energy as fat (34.9 versus 30.7%, P < 0.001). N7-MeG [mean: 95% confidence interval (CI)] levels were significantly lower in the group that consumed the highest proportion of dietary fibre/1000 kcal in comparison with the group with the lowest intake (0.61; 0.35-0.86 versus 1.88; 0.88-2.64 micromol/mol dG, P < 0.05). N7-MeG levels were also inversely associated with folate consumption (P < 0.05). MGMT activity (mean; 95% CI) was significantly higher in the group with the lowest consumption of vegetables than in the group with the greatest vegetable consumption (7.02; 5.70-8.33 versus 4.93; 3.95-5.91 fmol/microg DNA, P < 0.05). Our results are consistent with the hypothesis that dietary factors may modify exposure or susceptibility, respectively, to DNA damage by alkylating agents.

Human colorectal mucosal O6-alkylguanine DNA-alkyltransferase activity and DNA-N7-methylguanine levels in colorectal adenoma cases and matched referents.

BACKGROUND AND AIMS: O(6)-alkylguanine DNA-alkyltransferase (MGMT) provides protection against alkylating agent-induced GC-->AT transition mutations. Such mutations are frequently seen in the KRAS oncogene of large colorectal adenomas, but whether adenoma or mutational risk in humans is influenced by MGMT activity and alkylating agent exposure is unclear. Hence, MGMT activity and, as an indicator of alkylating agent exposure, DNA-N7-methylguanine (N7-MeG) levels were determined in the normal tissue of patients with and without adenomas. METHODS: Biopsy specimens of normal colorectal mucosa were collected during colonoscopy from 85 patients with histologically proved colorectal adenomas (cases) and from 85 patients free of gastrointestinal neoplasia (referents) matched by age, sex and biopsy location. MGMT activity and N7-MeG levels were measured in colorectal tissue extracts and DNA, respectively. RESULTS: MGMT activity was higher in the normal mucosa of cases than in referents (6.65+/-3.03 vs 5.61+/-2.74 fmol/micro g DNA, p = 0.01). On stratification of cases, MGMT activity was found to be considerably greater in the normal mucosa of cases with large adenomas (p = 0.003) and slightly higher in cases with a GC-->AT transition mutation in the K-ras gene (p = 0.03). Elevated MGMT levels were associated with an increased risk of adenoma (OR 1.17, 95% CI 1.03 to 1.33 per unit increase in activity). Detectable levels of N7-MeG were found in DNA from 89% of cases and 93% of referents, with levels ranging from <0.1 to 7.7 micro mol/mol dG. Cases and referents had similar DNA-N7-MeG levels. CONCLUSIONS: Human exposure to methylating agents is widespread. MGMT activity is increased in the normal mucosa of patients with adenomas.

Long-term results of the antegrade continent enema procedure for constipation in adults.

OBJECTIVE: The aim of this study was to evaluate the long-term results of the Antegrade Continent Enema (ACE) procedure for treating severe constipation in adults. METHODS: Over 10 years 37 ACE conduits were created in 32 patients (median age 35 years, 26 women) with constipation caused by slow transit, obstructed defaecation or both. Conduits were created from the appendix (n = 20, 54%), ileum (n = 10, 27%), neoappendix caecostomy (n = 5, 14%) or colon (n = 2, 5%). Clinical records were retrospectively reviewed to determine outcome. RESULTS: After a median follow up of 36 (range 13-140) months, 28 (88%) required at least one further procedure on a primary conduit, including reversal in 19 (59%). Five patients had a second conduit fashioned, two successfully. Conduit type and constipation cause did not significantly influence the rates of ACE reversal or major revision. Ileal conduits were associated with fewer minor revision procedures for stenosis (1 in 7 patients) than appendix conduits (21 in 20 patients). There was one (3%) serious complication. Satisfactory ACE function was ultimately achieved in 47% of patients, at last follow up. After ACE reversal, 9 (28%) patients underwent formation of an end stoma and 3 patients had a colectomy. CONCLUSIONS: Revision procedures are common, but approximately half of patients can expect satisfactory long-term ACE function. ACE conduit reversal does not preclude subsequent alternative surgical strategies to treat this difficult condition.

Longitudinal variation in O(6)-alkylguanine DNA-alkyltransferase activity in the human colon and rectum.

In a systematic study of O(6)-alkylguanine DNA-alkyltransferase activity in the human colon and rectum, tumours were found to occur in regions of low activity. These results are consistent with the hypothesis that O(6)-alkylguanine DNA-alkyltransferase levels and alkylating agent exposure may be important determinants of large bowel tumorigenesis.

Development and application of a sensitive and rapid immunoassay for the quantitation of N7-methyldeoxyguanosine in DNA samples.

N7-Methyldeoxyguanosine (N7-MedG) in DNA is a biomarker of exposure to environmental and endogenous methylating agents and may be of use in epidemiological studies. To quantitate N7-MedG in human samples, a sensitive assay system that uses only small quantities of DNA (<10 microg) is required. To this end, polyclonal antibodies against the imidazole ring-opened form of N7-MedG have been used to develop a highly sensitive immunoslot blot (ISB) assay. The limit of detection of the assay is 0.10 micromol of N7-MedG/mol of deoxyguanosine (dG) using 1 microg of DNA per analysis. The method was optimized using in vitro-methylated calf thymus DNA and then applied to a study of DNA methylation in liver and brain tissues of mice following a single iv dose of the antitumor agent Temozolomide. The amount of N7-MedG in both tissues was strictly proportional to dose over a range of 10-200 mg of Temozolomide/kg of body weight. The ISB assay was then validated using pyloric DNA of rats treated with N-methyl-N'-nitro-N-nitrosoguanidine and DNA samples from human bladder tumors, for both of which N7-MedG levels had already been quantitated by an HPLC/(32)P-postlabeling method previously described. The results showed a high degree of correlation (r = 0.98) between the two assays. The ISB assay was then applied to a range of human samples. A series of peripheral blood mononuclear cell DNA samples from cancer patients following treatment with Temozolomide had levels of N7-MedG ranging from 0.22 to 320 micromol/mol of dG. DNA samples from colon carcinoma and normal colorectal mucosa from individuals not known to be exposed to methylating agents contained levels of 0.11-1.34 micromol of N7-MedG/mol of dG. The ISB assay offers the potential for the rapid and high-throughput analysis of DNA obtained from routine biopsies and blood samples, thus enabling the determination of the extent of human exposure to environmental and endogenous sources of methylating agents in large-scale biomonitoring studies.