Colm P. McMahon

The efficiency of immobilised glutamate oxidase decreases with surface enzyme loading: an electrostatic effect, and reversal by a polycation significantly enhances biosensor sensitivity.

The apparent Michaelis constant, K(M), for glutamate oxidase (GluOx) immobilised on Pt electrodes increased systematically with enzyme loading. The effect was due, at least in part, to electrostatic repulsion between neighbouring oxidase molecules and the anionic substrate, glutamate (Glu). This understanding has allowed us to increase the Glu sensitivity of GluOx-based amperometric biosensors in the linear response region (100+/-11 nA cm(-2)microM(-1) at pH 7.4; SD, n=23) by incorporating a polycation (polyethyleneimine, PEI) to counterbalance the polyanionic protein. Differences in the behaviour of glucose biosensors of a similar configuration highlight a limitation of using glucose oxidase as a model enzyme in biosensor design.

The selectivity of electrosynthesised polymer membranes depends on the electrode dimensions: implications for biosensor applications

A biosensor selectivity coefficient defined for poly(o-phenylenediamine) electrosynthesised onto Pt microdisks and cylinders was unexpectedly found to change as the scale of the electrodes decreased, mainly due to enhanced permeability of a ubiquitous interference species in biological systems, ascorbic acid.

323 Chemotherapy Induced Diarrhea in Colorectal Cancer: A Retrospective Analysis of Clinico-Pathological and Radiological Features

number of goblet cells by endoscopic duodenum biopsies before and during chemotherapy. Degree of diarrhea was evaluated by NCI-CTC V4.0. Nutrition was evaluated by serum albumin and serum total protein before, during and after chemotherapy. Results:The mean DAO activities(± SD) in 20 patients were 4.88±2.06U/L before chemotherapy, 2.96±1.62U/ L during chemotherapy(day14) and 3.66±1.27U/L after drug holiday(day21). The DAO activity decreased significantly during chemotherapy and recovered significantly after drug holiday. Diarrhea(Grade1-3) appeared in 19 patients in the 10 to 18 day after administration of anticancer drugs and followed decrease in DAO activity. Villous height, villous surface area, the number of goblet cells were all significantly reduced by anticancer drugs and followed decrease in DAO activity. Serum albumin and serum total protein were significantly reduced by anticancer drugs and significantly increased after drug holiday. The DAO activity reduction rate between day1 and day14 was significantly correlated with albumin and total protein reduction rate between day1 and day21. Conclusion:Our results suggested that the DAO activity was useful as an indicative marker for intestinal mucosal damage, appearance of diarrhea and malnutrition in patients with chemotherapy.

Mo1910 Visceral Adiposity Is a Risk Factor for Poor Prognosis in Colorectal Cancer Patients Receiving Adjuvant Chemotherapy

Background Studies utilizing body mass index (BMI) have failed to show a consistent relationship between obesity and survival following treatment for colorectal cancer (CRC). Computerized tomography (CT) offers a reliable alternative approach to quantify body adiposity. We hypothesized that visceral obesity may negatively impact survival in CRC patients.