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This book will explain the colossal potential of life to cope with different living environments is possible owing to the exceptionally well developed mechanisms of adaptation to environmental conditions. There is an innumerable variety of concrete mechanisms which make it possible for living creatures to adapt to different and changing environmental conditions. Nevertheless, all this variety is the manifestation of the three strategic line of the adaptation process: 1. Evolutional or genotypic adaptation. 2. Phenotypic adaptation. 3. Rapid adaptation.
The general process of lipid peroxidation consists of three stages: initiation, propagation, and termination. The initiation phase of lipid peroxidation includes hydrogen atom abstraction. Several species can abstract the first hydrogen atom and include the radicals: hydroxyl, alkoxyl, peroxyl, and possibly HO* 2. The membrane lipids, mainly phospholipids, containing polyunsaturated fatty acids are predominantly susceptible to peroxidation because abstraction from a methylene group of a hydrogen atom, which contains only one electron, leaves at the back an unpaired electron on the carbon. The initial reaction of *OH with polyunsaturated fatty acids produces a lipid radical (L*), which in turn reacts with molecular oxygen to form a lipid hydroperoxide (LOOH). Further, the LOOH formed can suffer reductive cleavage by reduced metals, such as Fe++, producing lipid alkoxyl radical (LO*). Peroxidation of lipids can disturb the assembly of the membrane, causing changes in fluidity and permeability, alterations of ion transport and inhibition of metabolic processes. In addition, LOOH can break down, frequently in the presence of reduced metals or ascorbate, to reactive aldehyde products, including malondialdehyde (MDA), 4-hydroxy-2-nonenal (HNE), 4-hydroxy-2-hexenal (4-HHE) and acrolein. Lipid peroxidation is one of the major outcomes of free radical-mediated injury to tissue mainly because it can greatly alter the physicochemical properties of membrane lipid bilayers, resulting in severe cellular dysfunction. In addition, a variety of lipid by-products are produced as a consequence of lipid peroxidation, some of which can exert beneficial biological effects under normal physiological conditions. Intensive research performed over the last decades have also revealed that by-products of lipid peroxidation are also involved in cellular signalling and transduction pathways under physiological conditions, and regulate a variety of cellular functions, including normal aging. In the present collection of articles, both aspects (adverse and benefitial) of lipid peroxidation are illustrated in different biological paradigms. We expect this eBook may encourage readers to expand the current knowledge on the complexity of physiological and pathophysiological roles of lipid peroxidation.
This two-volume text compiles the efforts of distinguished scientists nd focuses on the formation of free radicals, toxic effects of lipoperoxides, biological antioxidant protection against lipid peroxidation damage, and pathological implications of lipid peroxidation. This review also addresses vitamin E deficiency, carbon tetrachloride and ethanol poisoning, radiation damage, hyperbaric effects, tumors, aging, diabetes, liver degeneration, DNA damage, lipoprotein modification and artherosclerosis, multiple sclerosis, angiopathy, Parkinson's disease, lupus, and many other degenerative diseases. It is an excellent resource for biological chemist, cell biologists, and all who are interested in the pharmaceutical sciences.
This book contains the proceedings of the ARW NATO Conference on "Action of Free Radicals and Active Forms of Oxygen on Lipoproteins and Membrane Lipids: Cellular Interactions and Atherogenesis", held in Bendor, France, October 5-8,1988. Since the pioneer work of Mc Cord and Fridovitch, growing interest has been focused on the study of the role of oxyradicals role in pathology. This interest is reflected in the exponential increase in the number of papers on free radicals, the success of specialized journals and books on this theme, and the organization of national and international meetings. These meetings have discussed, from.a broad point of view, the problems concerning the mechanisms of production of free radicals, their effects on cell CO!1$tituants (lipids, proteins, nucleic acids) and cell function, the methods of analysis of these phenomena, the pathological states in which free radicals may be involved, natural biological defense systems, and the design of "antiradical" therapies. But it is now well established that the most common target of oxy free radicals are membrane lipids because of their chemical nature (cholesterol in saturation, malonic linkage of polyunsaturated fatty acids (PUFA» and of their regular structural arrangement (monolayers in lipoproteins, bilayers in cell membranes). Thus the analysis of the products resulting from the action of oxy free radicals on PUFA is considered the best tool to indirectly evaluate the effects of tissue peroxidations, although the analytical basis for doing so is very questionable.
The general process of lipid peroxidation consists of three stages: initiation, propagation, and termination. The initiation phase of lipid peroxidation includes hydrogen atom abstraction. Several species can abstract the first hydrogen atom and include the radicals: hydroxyl, alkoxyl, peroxyl, and possibly HO* 2. The membrane lipids, mainly phospholipids, containing polyunsaturated fatty acids are predominantly susceptible to peroxidation because abstraction from a methylene group of a hydrogen atom, which contains only one electron, leaves at the back an unpaired electron on the carbon. The initial reaction of *OH with polyunsaturated fatty acids produces a lipid radical (L*), which in turn reacts with molecular oxygen to form a lipid hydroperoxide (LOOH). Further, the LOOH formed can suffer reductive cleavage by reduced metals, such as Fe++, producing lipid alkoxyl radical (LO*). Peroxidation of lipids can disturb the assembly of the membrane, causing changes in fluidity and permeability, alterations of ion transport and inhibition of metabolic processes. In addition, LOOH can break down, frequently in the presence of reduced metals or ascorbate, to reactive aldehyde products, including malondialdehyde (MDA), 4-hydroxy-2-nonenal (HNE), 4-hydroxy-2-hexenal (4-HHE) and acrolein. Lipid peroxidation is one of the major outcomes of free radical-mediated injury to tissue mainly because it can greatly alter the physicochemical properties of membrane lipid bilayers, resulting in severe cellular dysfunction. In addition, a variety of lipid by-products are produced as a consequence of lipid peroxidation, some of which can exert beneficial biological effects under normal physiological conditions. Intensive research performed over the last decades have also revealed that by-products of lipid peroxidation are also involved in cellular signalling and transduction pathways under physiological conditions, and regulate a variety of cellular functions, including normal aging. In the present collection of articles, both aspects (adverse and benefitial) of lipid peroxidation are illustrated in different biological paradigms. We expect this eBook may encourage readers to expand the current knowledge on the complexity of physiological and pathophysiological roles of lipid peroxidation.
Many studies have shown that free radical damage and lipid peroxidation increase as a function of the degree of unsaturation of the fatty acids present in the phospholipids of biological membranes. Membrane phospholipids are particularly susceptible to oxidation not only because of their highly polyunsaturated fatty acid content but also because of their association in the cell membrane with non-enzymatic and enzymatic systems capable of generating pro-oxidative-free radical species. There are two broad outcomes to lipid peroxidation: structural damage to membranes and generation of secondary products. Membrane damage derives from the generation of fragmented fatty acyl chains, lipidlipid cross-links, lipidprotein cross-links and endocyclisation to produce isoprostanes and neuroprostanes. These processes combine to produce changes in the biophysical properties of membranes that can have profound effects on the activity of membrane-bound proteins. The consequence of peroxidation of unsaturated fatty acids is severe: damage of membranes function, enzymatic inactivation, toxic effects on the cellular division, etc. This new book presents and discusses current research on oxidative stress, and lipid oxidation non-inhibited and inhibited; assessment of oxidative balance in the lipo- and hydro-philic cellular environment in biological systems; mass spectrometry detection of protein modification by cross-reaction with lipid peroxidation products; diagonal gel electrophoretic analysis of protein disulfides: principles and applications. Other chapters describe: heavy metals exposure and cells oxidative damage; biodegradation of metallic biomaterials: its relation with the generation of reactive oxygen species; Oxidative modifications of proteins in the aging heart; role of reactive oxygen species as signalling molecules involved in the regulation of physiological processes of the nervous system; oxidative stress in diabetes and hypertension treated with alternative therapy of medicinal plants; impairment of redox homeostasis of tissue damage in inborn errors of metabolism with intoxication: insights from human and animal studies and finally lipid peroxidation of phospholipids in the vertebrate retina or in liposomes made of retinal lipids: similarities and differences are described.
Current Topics in Membranes provides a systematic, comprehensive, and rigorous approach to specific topics relevant to the study of cellular membranes. This volume consist of eleven chapters from experts in the field that encompass free-radical effects on diverse membrane functions, ranging from selective barrier functions, controlling membrane protein function to discussing how the hydrophobic environment within membranes regulate free radical reactivity. The focus is on articles discussing specific examples in which membranes from different cellular compartments (e.g. plasma, ER, mitochondria) and membrane proteins either regulate reactive species formation and reactivity or are specific targets of reactive species leading to alteration in function. Provides overviews on biomembranes and the impact their physico-chemical properties have on reactive species reactivity Focuses is on reactive species and control of cell-signaling pathways Illustrates the concept that different reactive species can modulate function of specific membrane ion channels in different tissues, including sodium channels, chloride channels, sodium-potassium ATPases and calcium channels in both plasma and intracellular organelle membranes
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.
In our first protocols book, Free Radical and Antioxidant Protocols (1), r- erence to in vivo, ex vivo, or in situ techniques were few compared to classical biochemical assays and only 6 of the 40 chapters were concerned with these applications. In our second book, Oxidative Stress Biomarkers and Antioxidant Protocols (2), which is being published concurrently with this third volume, Oxidants and Antioxidants: Ultrastructure and Molecular Biology Protocols, the number of such chapters has increased. The literature dealing with histoche- cal/cytochemical and immunohistochemical techniques and staining to identify cellular/subcellular sites of oxidative stress has expanded rapidly, as has the molecular biology methodology used to analyze free radical and antioxidant (AOX) reactions, as well as the monitoring of living tissue. A two-way search was performed for each technique listed in Table 1, coupled with “oxidative stress” using the PUBMED search engine from the National Library of Medicine at NIH. Most of the techniques involved in m- suring oxidative stress employ molecular biology or ultrastructural approaches. Of these techniques, histology, polymerase chain reaction, and Western blotting are the most widely used. Several forms of therapy are now available for patients with increased oxidative stress. In addition to standard antioxidant therapy supplementation in vivo and in vitro, photodynamic therapy (PDT) employs excitation of a photon-emitting compound delivered systemically for free radical-mediated necrosis of affected tissues, and stem cells are also being used to induce signaling events or replace antioxidant enzymes.
Seafoods are important sources of nutrients for humans. Proteins and non protein nitrogenous compounds play an important role in the nutritional value and sensory quality of seafoods. Consumption of fish and marine oils is also actively encouraged for the prevention and treatment of cardio vascular diseases and rheumatoid arthritis. Highly unsaturated long-chain omega-3 fatty acids are regarded as the active components of marine oils and seafood lipids. The basic chemical and biochemical properties of seafood proteins and lipids, in addition to flavour-active components, their microbiological safety and freshness quality, are important factors to be considered. A presentation of the state-of-the-art research results on seafoods with respect to their chemistry, processing technology and quality in one volume was made possible by cooperative efforts ofan international group of experts. Following a brief overview, the book is divided into three sections. In Part 1 (chapters 2 to 8) the chemistry of seafood components such as proteins, lipids, flavorants (together with their properties and nutritional significance) is discussed. Part 2 (chapters 9 to 13) describes the quality of seafoods with respect to their freshness, preservation, micro biological safety and sensory attributes. The final section of the book (chapters 14 to 16) summarizes further processing of raw material, underutilized species and processing discards for production of value added products.