s / International Journal of Surgery 8 (2010) 501–578 531 IS THERE AN ASSOCIATION BETWEEN RADON EXPOSURE AND THE INCIDENCE OF THYROID CANCER? Venkat M. Reddy , Andrew Lau , Tarig Abdelrahman , Andrew J. Carswell . 1 Royal Cornwall Hospital NHS Trust; University Hospitals Bristol NHS Trust Introduction: Radon is a naturally occurring radioactive gas which is present in rocks and soils. High levels of radon exposure is known to increase the risk of lung cancer. Radon exposure has been implicated in thyroid cancer although there is little evidence to support this. The aim of this study is to investigate whether there is an association between the incidence of thyroid cancer and radon levels. Method: Age standardised incidence rates for thyroid cancer were calculated for each Strategic Health Authority (SHA) in England based on National Cancer Registry data from 1990-2006 and population estimates from the Office for National Statistics. Indicators of radon levels for the SHAs were calculated based on radon data from the Health Protection Agency. Results: Spearman's rank correlation did not identify any significant correlation between age standardised incidence rates for thyroid cancer and indicators of radon levels (number of properties at or above action level in SHA rho 1⁄4 0.06, p 1⁄4 0.88; percentage of dwellings measured rho 1⁄4 0.103, p 1⁄4 0.78; highest radon level recorded rho 1⁄4 0.164, p 1⁄4 0.651). Conclusion: There is no significant association between radon exposure and incidence of thyroid cancer on the basis of the data analysed in this study. PLATELET DERIVED CD154 MEDIATES HUMAN HEPATOCYTE DEATH DURING ISCHAEMIA-REPERFUSION INJURY R.H. Bhogal, D.H. Adams, S.C. Afford. University of Birmingham Background: During liver transplantation, hepatocytes are exposed to periods of hypoxia and reoxygenation, as a consequence of ischemiareperfusion injury (IRI). Reactive Oxygen Species (ROS) modulate hepatocyte death during IRI. Activation of hepatocyte CD40, a Tumour Necrosis Factor Receptor super-family member, by it's ligand CD154 is known to effect allograft rejection. Whether CD40 activation can result in ROS accumulation and human hepatocyte injury is not known. Hypothesis: Hypoxia and reoxygenation drive hepatocyte ROS production which sensitise cells to CD40 mediated apoptosis. Methods: Human hepatocytes were isolated from liver tissue and exposed to hypoxia and reoxygenation in the presence or absence of recombinant or platelet derived CD154. ROS production, apoptosis and necrosis were determined by labelling cells with 2',7'-dichlorofluorescin, Annexin-V and 7-AAD respectively followed by flow cytometry. Results: Hepatocytes increased ROS accumulation during hypoxia and reoxygenation resulting in increased necro-apoptosis. Co-incubation of hepatocytes with CD154 augmented ROS accumulation during hypoxia and reoxygenation enhancing necro-apoptosis. Activated platelets secrete CD154 which also mediated hepatocyte injury during hypoxia and reoxygenation. Conclusions: CD40 activation by platelet-derived CD154, increases ROS production enhancing human hepatocyte injury during IRI. This novel finding suggests that inhibition of CD154-stimulated ROS provides a potential avenue to limit liver damage following transplantation. LEFT INTERNAL MAMMARY ARTERY IN CORONARY ARTERY BYPASS GRAFTING AND JUSTIFICATION FOR NON-USE N.A. Hirst, R.W. White. Cardiothoracic Unit, Leeds General Infirmary, Yorkshire, UK Left internal mammary artery (LIMA) is currently considered the conduit of choice to the left anterior descending artery (LAD) in surgical revascularisation. It is proven to offer better long-term patency and patient survival compared with saphenous vein grafts (SVG). We analysed all patients having surgical revascularisation over a 12-month period, establishing rate of LIMA usage, and rationale for non-use. Of 780 patients, 562 (72%) received LIMA to LAD. Of the 706 LADs grafted, 562 (78.6%) were with LIMA, 3 with other arterial conduit, and 141 SVG. Reasons established for not using LIMA were: small LAD (LIMA grafted to alternative vessel), poor quality LIMA, emergency surgery, obesity, concurrent valve surgery, and significant pulmonary disease. However, reasons were not stated in 93 of 126 operation notes (74%). LIMA usage varied from 60% to 95% between surgeons. Low cardiac output, renal failure, atrial fibrillation, transfusion rate, hospital stay and mortality were lower in the LIMA group. Re-exploration rate and sternal complications were higher in the LIMA group. LIMA to LAD should be the goal for surgical revascularisation, accepting that there may be contra-indications to use. Reasons for non-use should be recorded, if to be used as a quality indicator. A NOVEL NANOCOMPOSITE POLYMER AS A POTENTIAL SCAFFOLD IN ATTEMPTS TO TISSUE ENGINEER SMALL INTESTINE Najib Daulatzai, Arnold Darbyshire, Marilena Loizidou, Alexander Seifalian, Marc Winslet. Academic Department of Surgery, University College London Medical School, Royal Free Hospital campus Introduction: Tissue engineering offers an exciting alternative approach to the management of short bowel syndrome. Aims: To evaluate mechanical properties and the in-vitro cell growth of rat intestinal stem cells on a novel, POSS-PCL polymer. Methods: Cells were seeded onto POSS-PCL discs and plastic wells in 24 well plates. ABF as a marker of cell growth was measured at days 7, 14 and 21. Toxicity was assessed using an LDH assay from sampled supernatant. Tensile strength properties were calculated using an Instron tensometer and viscosity using a Bohlin rheometer. Results: ABF was substantially increased at day 21 post seeding compared to day 14 and 7 (55.9 AFU vs. 15.6 AFU vs. 10.59 AFU, p < 0.001). LDH concentrations in POSS-PCL supernatants were comparably lower to plastic in all subgroups (Day 21; 0.78 u/ml vs. 2.64 u/ml, p < 0.001). Polymer viscosity was13 PaS and stress at break at 958%. Conclusions: The use of POSS-PCL polymer as a scaffold for tissue engineering small bowel is promising. The polymer shows minimal cellular toxicity and good tensile strength whilst acting as a framework that can sustain cellular growth and proliferation. POSS-PCL; Polyhydrel Oligomeric Silsesquixane modified Polycaprolactone ABF; Alamar Blue Fluorescence LDH: Lactate Dehydrogenase AFU; Arbitrary Fluorescent units TOUCH IMPRINT CYTOLOGY OF AXILLARY LYMPH NODES IN A DISTRICT GENERAL HOSPITAL SETTING: A FEASIBILITY STUDY S.L. Horn, E.F. Shah. Guy's Hospital, London; 2 Conquest Hospital, Hastings