Bacterial clearance of biologic grafts used in hernia repair: an experimental study.

BACKGROUND: Biologic grafts used in ventral hernia repair are derived from various sources and undergo different post-tissue-harvesting processing, handling, and sterilization techniques. It is unclear how these various characteristics impact graft response in the setting of contamination. We evaluated four materials in an infected hernia repair animal model using fluorescence imaging and quantitative culture studies. METHODS: One hundred seven rats underwent creation of a chronic hernia. They were then repaired with one synthetic polyester control material (n = 12) and four different biologic grafts (n = 24 per material). Biologic grafts evaluated included Surgisis (porcine small intestinal submucosa), Permacol (crosslinked porcine dermis), Xenmatrix (noncrosslinked porcine dermis), and Strattice (noncrosslinked porcine dermis). Half of the repairs in each group were inoculated with Staphylococcus aureus at 10(4) CFU/ml and survived for 30 days without systemic antibiotics. Animals then underwent fluorescence imaging and quantitative bacterial studies. RESULTS: All clean repairs remained sterile. Rates of bacterial clearance were as follows: polyester synthetic 0%, Surgisis 58%, Permacol 67%, Xenmatrix 75%, and Strattice 92% (P=0.003). Quantitative bacterial counts had a similar trend in bacterial clearance: polyester synthetic 1×10(6) CFU/g, Surgisis 4.3×10(5) CFU/g, Permacol 1.7×10(3) CFU/g, Xenmatrix 46 CFU/g, and Strattice 31 CFU/g (P=0.001). Fluorescence imaging was unable to detect low bacterial fluorescence counts observed on bacterial studies. CONCLUSION: Biologic grafts, in comparison to synthetic material, are able to clear a Staphylococcus aureus contamination; however, they are able to do so at different rates. Bacterial clearance correlated to the level of residual bacterial burden observed in our study. Post-tissue-harvesting processing, handling, and sterilization techniques may contribute to this observed difference in ability to clear bacteria.

Objective evaluation of the performance of surgical trainees on a porcine model of open colectomy.

BACKGROUND: Evaluation of surgical trainee operative performance is rarely objective. A rating system is proposed that assesses trainee performance objectively and quantifies technical improvement. METHODS: General surgery trainees were evaluated while performing porcine segmental colectomy. Initial instruction was provided for the critical operative steps. Evaluations were later repeated without additional instruction. Performance in 17 critical areas was scored. RESULTS: Twenty-three trainees were evaluated. Performance was divided into thirds, with a significant difference detected between tertiles (P < 0.001). Postgraduate year 2 trainees scored lower than those in years 3 and 4 (P < 0.001), but there was no difference between year 3 and 4 trainees (P = 0.557). Mean repeat scores were improved by 35 per cent, with most improvement at postgraduate year 2 level (71 per cent). Mean time taken to complete the operation was reduced by 23 per cent, with the largest reduction in the year 2 group. CONCLUSION: The results support the use of this rating system as a tool for the objective evaluation of trainee operative skill. Instruction in the performance of segmental colectomy using deconstructed, step-by-step direction improved the ability of junior trainees to complete the operation. This evaluation system may be useful in the assessment, instruction and technical development of surgical trainees.

Investigation of ATP6V1B1 and ATP6V0A4 genes causing hereditary hearing loss associated with distal renal tubular acidosis in Iranian families.

BACKGROUND: Hearing defects are the most common sensory disorders, affecting 1 out of every 500 newborns. ATP6V1B mutations are associated with early sensorineural hearing loss, whereas ATP6V0A4 mutations are classically associated with either late-onset sensorineural hearing loss or normal hearing. ATP6V1B1 and ATP6V0A4 genetic mutations cause recessive forms of distal renal tubular acidosis. METHOD: Ten unrelated deaf Iranian families with distal renal tubular acidosis were referred to the Genetics Research Centre, University of Social Welfare and Rehabilitation Sciences, Tehran. All exons of the ATP6V1B1 and ATP6V0A4 genes were sequenced in affected family members. RESULTS: We identified a previously reported ATP6V1B1 frameshift mutation (P385fsX441) in two families and a nucleotide substitution in exon 10 (P346R) in three families. In addition, one patient was homozygous for a novel nucleotide substitution in exon 3. CONCLUSION: ATP6V1B1 genetic mutations were detected in more than half of the families studied. Mutations in this gene therefore seem to be the most common causative factors in hearing loss associated with distal renal tubular acidosis in these families.

Saffron (Crocus sativus L.) extract prevents and improves D-galactose and NaNO2 induced memory impairment in mice.

This study was conducted to examine the effects of saffron extract on preventing D-galactose and NaNO2 induced memory impairment and improving learning and memory deficits in amnestic mice. In this study, the learning and memory functions in ovariectomized mice were examined by the one way passive and active avoidance tests. In active avoidance test, training in amnestic treated (AT) and amnestic prophylaxis (AP) groups, was improved so that there was a significant difference between them and the amnestic control (AC) group. In passive avoidance test, animal's step through latency, as an index for learning, in all test groups was significantly greater than control group. Total time spent in dark room (DS), which opposes the memory retention ability, in AC was significantly greater than AT group at 1 and 2 hours after full training, while there was not any significant difference between this index in AP and AT as compared with normal control (NC) group. Our findings indicate that saffron hydro-alcoholic extract prevents and improves amnesia induced by D-galactose and NaNO2 in mice.