An application of radiocarbon (14C) in atmospheric chemistry is reviewed. 14C produced by cosmic neutrons immediately forms 14CO, which reacts with hydroxyl radicals (OH) to 14CO2. By this the distribution and seasonality (the lifetime of 14CO is ∼1 month) of the pivotal atmospheric oxidant OH can be established. 14CO measurement is a complex but unique application which benefitted enormously from the realization of AMS, bearing in mind that 14CO abundance is of the order of merely 10 molecules per cm3 not only provides 14CO an independent measure for the OH based self-cleansing capacity of the troposphere, but also enabled detection of 14C production due to high energy solar protons in 1989. Although its production takes place throughout the atmosphere and does not have the character of a point source, transport processes in the atmosphere affect the distribution of 14CO. Vertical mixing in the troposphere renders gradients in its production rate less critical, but considerable meridional gradients exist. One question has remained open, namely confirmation of calculated 14C production by direct measurement. A new sampling method is proposed. The conclusions are a guide to future work on 14CO in relation to OH and atmospheric transport.

In our earlier work, we demonstrated that the oxidases tyrosinase (TYR), laccase (LAC), and a heme peroxidase (POX) occur widely in lichens. Here we report on the occurrence of another oxidoreductase enzyme, quinone reductase (QR) (EC 1.6.5.5). While QR has been reported to occur widely in other organisms, there is currently no information on QR activities in lichens. Here we present a survey of QR activity in 14 species of lichens. Results demonstrate that QR activity is readily detectable in all lichen species tested. However, activities vary greatly, with ‘jelly’ lichens in the genera Collema and Leptogium having the highest activities. QR, LAC and POX are all believed to have a role in extracellular hydroxyl radical production. However, in this study no correlation was found between the activities of these enzymes and the rates at which hydroxyl radicals were produced. Possible roles for QR in lichen biology are discussed.

Ergothioneine (ERG) is an unusual thio-histidine betaine amino acid that has potent antioxidant activities. It is synthesised by a variety of microbes, especially fungi (including in mushroom fruiting bodies) and actinobacteria, but is not synthesised by plants and animals who acquire it via the soil and their diet, respectively. Animals have evolved a highly selective transporter for it, known as solute carrier family 22, member 4 (SLC22A4) in humans, signifying its importance, and ERG may even have the status of a vitamin. ERG accumulates differentially in various tissues, according to their expression of SLC22A4, favouring those such as erythrocytes that may be subject to oxidative stress. Mushroom or ERG consumption seems to provide significant prevention against oxidative stress in a large variety of systems. ERG seems to have strong cytoprotective status, and its concentration is lowered in a number of chronic inflammatory diseases. It has been passed as safe by regulatory agencies, and may have value as a nutraceutical and antioxidant more generally.

Hydroxyl radical footprinting is a powerful technique often employed in characterization of the tertiary interactions between proteins and nucleic acids. Following the generation of a nucleic acid “ladder” either by chemical or enzymatic reactions, the radiolabeled products are traditionally separated by denaturing gel electrophoresis and further quantified by phosphorimaging techniques. Here we report the use of ion pair reverse phase liquid chromatography to analyze the products of an RNA footprinting reaction using fluorescently labeled RNA molecules. This technique offers several advantages over existing procedures, including rapid analysis, automation, and direct quantification of the cleavage products without the need to employ radiolabeling. To illustrate the resolving power of this technique, we have analyzed the products of base hydrolysis, generated from a fluorescently labeled RNA molecule and have subsequently used this method to define the solvent accessibility of the substrate strand as it docks with the hairpin ribozyme.

Background and objective We investigated whether glibenclamide (glyburide) affects myocardial metabolism and hydroxyl radical formation in the rat heart–lung preparation with or without inhalation anaesthetics.

Methods Thirty-seven male Wistar rats were allocated to four groups: (a) control group (C), received vehicle only; (b) group G, received glibenclamide 10 μM L−1; (c) group I, received glibenclamide 10 μM L−1 and 1.4% isoflurane during perfusion; (d) group S, received glibenclamide 10 μM L−1 and 2.7% sevoflurane during perfusion. Glibenclamide was administered 7 min after the start of perfusion. Ten minutes later, the heart was rendered globally ischaemic for 10 min by reducing the preload and afterload to zero, and then the heart was reperfused for 10 min. The formation of hydroxyl radicals in perfusate blood and heart was measured with high performance liquid chromatography using salicylic acid. Hydroxyl radicals react with salicylic acid, yielding dihydroxybenzoic acids.

Results The recovery time from ischaemia in group G was significantly longer than the other groups. However, there were no differences in myocardial metabolites and dihydroxybenzoic acids concentrations in the perfusate and heart among the four groups.

Conclusions Glibenclamide prolonged recovery time from ischaemia, but did not affect hydroxyl radical formation in the postischaemic reperfused heart. In addition, isoflurane and sevoflurane shortened this time. These facts suggest that mechanisms other than effects of volatile anaesthetics on hydroxyl radical formation are responsible for their protective effects in this model.

Sevoflurane has been reported to generate oxygen free radicals. We have investigated whether sevoflurane or isoflurane enhances oxygen free radical formation in the post-ischaemic reperfused heart. An isolated rat heart–lung preparation was used. Thirty male Wistar rats were allocated to four groups: control, no drug, 2.5% sevoflurane and 1.4% isoflurane. The heart was perfused initially at a cardiac output of 30 mL min−1 and a mean arterial pressure of 70 mmHg. Ten minutes after the start of perfusion, the heart was rendered globally ischaemic for 10 min by reducing the preload and afterload to zero. Then, the heart was reperfused for 10 min. At the end of reperfusion, the heart was freeze dried for 6 days. The perfusate blood was collected just before and just after ischaemia and at the end of reperfusion. The formation of hydroxyl radicals in perfusate blood and heart was measured with high-performance liquid chromatography using salicylic acid. Hydroxyl radicals react with salicylic acid, yielding 2,3-, 2,4-, 2,5- and 3,4-dihydroxybenzoic acid (DHBA). Before and after ischaemia, there were no significant differences in cardiac output, systolic pressure, heart rate and right arterial pressure among the groups. The concentrations of 2,3-, 2,4-, 2,5- and 3,4-DHBA in the perfusate blood after ischaemia and reperfusion were significantly higher than those before ischaemia in all groups. However, there were no differences in the DHBA levels among groups. This study indicates that sevoflurane and isoflurane do not enhance hydroxyl radical formation in the post-ischaemic reperfused heart.