Corona Discharge and Field Electron Emission in Ambient Air Using a Sharp Metal Needle: Formation and Reactivity of CO3 -• and O2 -•.

CO3 -• and O2 -• are known to be strong oxidizing reagents in biological systems. CO3 -• in particular can cause serious damage to DNA and proteins by H• abstraction reactions. However, H• abstraction of CO3 -• in the gas phase has not yet been reported. In this work we report on gas-phase ion/molecule reactions of CO3 -• and O2 -• with various molecules. CO3 -• was generated by the corona discharge of an O2 reagent gas using a cylindrical tube ion source. O2 -• was generated by the application of a 15 kHz high frequency voltage to a sharp needle in ambient air at the threshold voltage for the appearance of an ion signal. In the reactions of CO3 -•, a decrease in signal intensities of CO3 -• accompanied by the simultaneous increase of that of HCO3 - was observed when organic compounds with H-C bond energies lower than ∼100 kcal mol-1 such as n-hexane, cyclohexane, methanol, ethanol, 1-propanol, 2-propanol, and toluene were introduced into the ion source. This clearly indicates the occurrence of H• abstraction. O2 -• abstracts H+ from acid molecules such as formic, acetic, trifluoroacetic, nitric and amino acids. Gas-phase CO3 -• may play a role as a strong oxidizing reagent as it does in the condensed phase. The major discharge product CO3 -• in addition to O2 -•, O3, and NO x • that are formed in ambient air may cause damage to biological systems.

One-stop shop for variceal surveillance: integration of unsedated ultrathin endoscopy into the routine clinic visit.

BACKGROUND: The endoscopic appearance of oesophageal varices determines the need for prophylaxis. However, as the point prevalence of varices is low (25%), the majority of surveillance endoscopies are unnecessary and costly. Narrow diameter, ultrathin (UT) endoscopes are more tolerable than conventional upper gastrointestinal (UGI) endoscopes and can be used without sedation. We hypothesised that unsedated UT endoscopy for variceal surveillance could be implemented during the routine outpatient clinic visit allowing accurate diagnosis of varices and the timely provision of prophylaxis. METHODS: Patients with cirrhosis awaiting surveillance endoscopy were identified. UT endoscopy was scheduled during routine clinic review at the same time as ultrasound surveillance for hepatocellular carcinoma. UGI endoscopy was performed unsedated using the E.G Scan II disposable endoscope. Varices were graded using the modified Paquet classification. Video recordings of procedures were reviewed by blinded assessors and agreement was assessed using the kappa statistic. RESULTS: 40 patients (80% male) underwent unsedated UT endoscopy. All procedures were successful and tolerated well in 98% of cases. Median procedure time was 2 min (IQR 1-3). Varices were found in 37.5% (17.5% grade 1 and 20% grade 2). Patients with grade 2 varices were prescribed non-selective beta blockers at the clinic appointment. Kappa statistic for the finding of any varices was 0.636 (p=0.001) and 0.8-1.0 for diagnosis of grade 2 varices (p<0.0001). CONCLUSIONS: Outpatient unsedated ultrathin endoscopy in patients with cirrhosis is accurate, safe and feasible. This integrative care model is convenient, particularly for regional communities, and is likely to result in significant cost savings associated with variceal surveillance.