Packer - Böcker

Antioxidants inhibit the formation and spread of free radicals which can be damaging in biological systems. Free radicals form in biological systems through metabolism, but it is also realized that exogenous environmental sources, such as radiation, food, and drugs, contribute significantly to the generation of free radicals in biological systems. Being reactive species, free radicals are short-lived and do not travel far from cellular targets. Their concentration in biological systems is very low and is difficult to detect directly by electron spin resonance spectroscopy (ESR). Indirect methods of reactions of radicals with specific biomolecules are also sufficiently sensitive to detect quantitatively their presence. Thus the response of antioxidant defenses which react with radical species, can serve as an indirect measure that free radicals have been formed. Redox-based antioxidants change their oxidation state and antioxidants become free radicals themselves. Often, however, the antioxidants give rise to more persistent free radicals, sometimes owing to delocalization of the lone electron around ring structures (in vitamin E, ubiquinones, and certain carotenes). Persistent free radicals react only rarely and the precursors often can be regenerated in biological systems. In recent years, it is becoming clearer from biochemical studies on how the major lipophilic antioxidants work. Particular attention has been given to vitamin E and quinones found in animal and plant membranes and in carotenoids, for the protection of membranes in lipoprotein systems. Flavonoids form another rich and varied source of natural antioxidants.

It is well known that basic science can trigger an invention of considerable technological and commercial importance. Indeed basic science and invention are often inextricably linked, each being able to catalyse the other. To engender such developments it is important that there should be good communication between the scientist and the technologist. The field of membrane biotechnology is a growing field where such communication is increasingly taking place and where new inventions are occurring. This book provides an overview of this developing field. It contains chapters by scientist and technologists working in the field of Membrane Biotechnology. The chapters cover the latest advances in basic science as well as some recent technological applications. The basic topics include the application of dynamic X-ray diffraction to lipid water systems, FTIR spectroscopy applied to membrane proteins, fluorescent analogues of phosphoinositides, studies of platelet activating factor, antibody binding to model membranes and phospholipase C induced fusion. The technological topics described include the development of new haemocompatible materials based upon biomembrane mimicry, new lung surfactant materials, drug delivery systems including liposomes and the development of new biosensors including Langmuir Blodgett films. The meeting showed that there are many other useful applications in the pipeline. The potential for new polymeric drug delivery systems, of ion selective systems based on the knowledge of ion-channel protein structures, of new plastics for cell growth and cellular engineering for artificial organs. These are among the interesting developments that are emerging in this field.

Skeletal muscle consumes significant amounts of oxygen, and its oxygen flux increases significantly under conditions of exercise and muscle contraction. This makes the muscle vulnerable to oxidative stress since concomitantly with the increase of oxygen flow there is an increase of free oxygen radicals which are a byproduct of muscle respiration. A number of studies in the last decade have documented the involvement of free oxygen radicals in exercising muscles. The consequences of muscle oxidative stress have resulted mainly in increased muscle protein oxidation, elevation of lipid peroxidation, and depletion of muscle antioxidants. The mechanisms of this oxidative stress are under extensive investigation in laboratories around the world and are topics of the chapters in this volume. This book is intended for professionals who are interested in muscle function, physiology, pathophysiology and well-being, such as therapists, trainers and medical professionals as well as for researchers in the field of muscle physiology.