BioFactors 24 (2005) 1–4 1 IOS Press Editorial HNE and Further Lipid Peroxidation Products 1. Products of lipid peroxidation used as biomarkers of oxidative stress Oxygen free radicals are implicated in many diseases and “normal” processes, such as ischemia- reperfusion injury (see myocardial infarction and stroke), cataracts, age-related macula degeneration, cancer, inflammation, aging, diabetes, and neurodegenerative diseases. Assessment of oxidative stress by measurement of lipid peroxidation (LPO) products is of biological and clinical importance when considering the multiple functions of lipids such as steroid hormones, retinoic acids, and prostaglandins. Beyond, LPO products such as 4-hydroxynonenal (HNE), acrolein, F2-isoprostanes, and oxysterols exert signal functions that significantly influence gene expression and protein synthesis, and such regulatory phenomena may affect the organism more dramatically. In short, LPO is biologically and medically important. When establishing methods for LPO measurement, one has to take into account which phase of LPO, its initiation, propagation, or termination, is to be characterized. If unstable carbon radicals are formed from fatty acids, conjugated dienes as next group of intermediates are generated by molecular rearrangement. By oxygen uptake then peroxyl radicals and, by hydrogen abstraction, lipid hydroperoxides are formed. These primary oxidation products generate secondary LPO products, such as malondialdehyde (MDA), HNE, and other aldehydes, short-chain alkanes, isoprostanes etc. Analyzing LPO therefore means either to determine the formation of oxidized products (e.g. short-chain alkanes, aldehydic LPO products, F2-isoprostanes, or oxysterols) or to monitor the loss of regular cellular constituents (substrate loss; compounds which get used up during oxidative stress, e.g. PUFA), and each approach will answer distinct questions only. Groups of analytically accessible LPO intermediates and products, which are also found in biological systems, are compiled in Fig. 1. 2. Berlin Meeting “HNE and Further Lipid Peroxidation Products: From Basic Science to Medicine” The Berlin Meeting “HNE and Further Lipid Peroxidation Products: From Basic Science to Medicine” was organized by the HNE-Club and the Society for Free Radical Research Europe. It was the second Meeting of the HNE-Club after the first one held in Salzburg, Austria. The organizational burden had been shouldered by Tilman Grune, Department of Environmental Medicine at Heinrich-Heine University Duesseldorf, Werner Siems, Research Institute of Physiotherapy and Gerontology at Loges-School Bad Harzburg, and Olaf Sommerburg, Department of Pediatrics at University Ulm. The Meeting was held in 0951-6433/05/$17.00  2005 – IOS Press and the authors. All rights reserved