Oxygen Radicals: Systemic Events and Disease Processes [antikvár]

Foreword In the year 2000 we will celebrate the centennial of Gomberg's discovery of free radicals - molecules that have missing atoms or groups. These unusual species with a ubiquitous unpaired electron defied the classical tenets of chemistry. It is interesting that this discovery involved stable free radicals. As a general rule, the majority of free radicals are extremely reactive and, consequently, short-lived species due to the presence of the unpaired electron. The technology in 1900, however, could not handle transient entities with very short lifetimes. It is remarkable, therefore, that Gomberg followed the only possible lead, which was the exception rather than the rule, namely, the stable free radicals. A relatively stable species, such as Gomberg's triphenylmethyl radical, is not found under normal physiological conditions, and the research of free radicals in biosystems had to await further developments. In the 1930s Michaelis considered the formation of free radicals in bichemical reactions via one-electron transfer mechanisms, but again the proposition was premature. The major advances in free-radical chemistry that raised interest in bioradicals were brought about by the development of nuclear energy in the 1940s and 1950s. A great deal was learned from direct ESR measurements of 'frozen' radicals generated by radiation and the products of free-radical reactions in the aqueous phase under station-ary-state conditions. It is, however, the development of pulse radiolysis in 1962 by Hart, Boag, and Keene that marked the turning point in free radical research. Now the technology was available for kinetic detection and monitoring of short-lived radicals generated by submicrosecond pulses of high-energy (2 - 10 MeV) electrons. The next 4 years bristled with excitement because the rate constants of free-radical reactions, hitherto unaccessible, became available. Information about the reactivities and properties of hundreds of free radicals in model aqueous and organic systems paved the way for the discovery of the superoxide radical in biosystems by McCord and Frid-owich in the late 1960s. This major discovery marked a turning point in free-radical research in biology and medicine. This book deals with free-radical processes and their deleterious consequences in biosystems. It is cleaj^^tflJJ^jthai, human physiology is