Article

New anti-RNS and -RCS products for cosmetic treatment

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Abstract

Oxidants and free radicals are known to be a very important factor in skin aging, taking an active part in lipidic peroxidation, breakage of proteins and DNA, etc. The most well-known are reactive oxygen species (ROS), for example, superoxide radical anion, or more commonly called, superoxide (O), hydroxyl radical (OH(*)) or hydrogen peroxide (H(2)O(2)). Both free radicals and other oxidants can be generated by metabolic activity within the cell and by other environmental challenges,. In addition, other dangerous species are known such as reactive nitrogen species (RNS) and reactive carbonyl species (RCS). Some of the most important RNS are peroxynitrite (ONOO(-)), nitrogen dioxide radical ((*)NO(2)) and the nitronium ion (NO). For RCS, some of the most important are 4-hydroxynonenal (HNE), acrolein (ACR), malondialdehyde (MDA) or glyoxal (GXL). Both compounds (RNS and RCS) are thought to play an important role in many diseases and in skin aging, for example, collagen cross-linking, DNA damage, protein tyrosine nitration, etc. This work investigates two new specific chemicals: Lipochroman-6((R))- an anti-RNS which shows good results in inhibiting the nitration of tyrosine by peroxynitrite, and Aldenine((R))- a tripeptide anti-RCS which protects cells from reactive carbonyl compounds such as HNE or ACR; it also shows the ability to prevent glycation of proteins, specifically by superoxide dismutase (SOD).

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... Peroxynitrite reacts with tyrosine to form 3-nitrotyrosine, leading to irreversible modifications in proteins and compromising the interconversion between the phosphorylated and dephosphorylated states of kinase substrates, a major mechanism of cellular signaling. Additionally, peroxynitrite damages important constituents of the extracellular matrix (ECM) like hyaluronic acid [29]. The data indicate that MeO-MBM is an antioxidant with additional photoantioxidative properties on the cellular level. ...
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Chapter
The copper-binding tripeptide GHK (glycyl-l-histidyl-l-lysine) is a naturally occurring plasma peptide widely used in skin care products. It is especially popular in antiaging cosmetic formulations due to its various and well-established positive biological effects on aging skin. It has been established that GHK-Cu improves wound healing and tissue regeneration and stimulates collagen and decorin production. GHK-Cu also supports angiogenesis and nerve outgrowth, improves the biological condition of aging skin and hair and possesses DNA repair, antioxidant, and anti-inflammatory effects. In addition, it increases cellular stemness and secretion of trophic factors by mesenchymal stem cells. GHK’s antioxidant actions have been demonstrated in vitro and in animal studies. They include blocking the formation of reactive oxygen and carbonyl species, detoxifying toxic products of lipid peroxidation such as acrolein, protecting keratinocytes from lethal UVB radiation, and blocking hepatic damage by dichloromethane radicals. In recent studies, GHK has also been found to switch cellular gene expression from a diseased state to a healthier state for certain cancers and for chronic obstructive pulmonary disease (COPD). The human gene expression actions provide a unique view of the complex and intricate gene actions underlying visible changes in human skin. This chapter reviews biological and gene data related to the positive antiaging effects of GHK on human skin.
Chapter
The copper-binding tripeptide GHK (glycyl-l-histidyl-l-lysine) is a naturally occurring plasma peptide widely used in skin care products. It is especially popular in antiaging cosmetic formulations due to its various and well-established positive biological effects on aging skin. It has been established that GHK-Cu improves wound healing and tissue regeneration and stimulates collagen and decorin production. GHK-Cu also supports angiogenesis and nerve outgrowth, improves the biological condition of aging skin and hair and possesses DNA repair, antioxidant, and anti-inflammatory effects. In addition, it increases cellular stemness and secretion of trophic factors by mesenchymal stem cells. GHK’s antioxidant actions have been demonstrated in vitro and in animal studies. They include blocking the formation of reactive oxygen and carbonyl species, detoxifying toxic products of lipid peroxidation such as acrolein, protecting keratinocytes from lethal UVB radiation, and blocking hepatic damage by dichloromethane radicals. In recent studies, GHK has also been found to switch cellular gene expression from a diseased state to a healthier state for certain cancers and for chronic obstructive pulmonary disease (COPD). The human gene expression actions provide a unique view of the complex and intricate gene actions underlying visible changes in human skin. This chapter reviews biological and gene data related to the positive antiaging effects of GHK on human skin.
Chapter
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Cardiovascular complications, characterized by endothelial dysfunction and accelerated atherosclerosis, are the leading cause of morbidity and mortality associated with diabetes. There is growing evidence that excess generation of highly reactive free radicals, largely due to hyperglycemia, causes oxidative stress, which further exacerbates the development and progression of diabetes and its complications. Overproduction and/or insufficient removal of these free radicals result in vascular dysfunction, damage to cellular proteins, membrane lipids and nucleic acids. Despite overwhelming evidence on the damaging consequences of oxidative stress and its role in experimental diabetes, large scale clinical trials with classic antioxidants failed to demonstrate any benefit for diabetic patients. As our understanding of the mechanisms of free radical generation evolves, it is becoming clear that rather than merely scavenging reactive radicals, a more comprehensive approach aimed at preventing the generation of these reactive species as well as scavenging may prove more beneficial. Therefore, new strategies with classic as well as new antioxidants should be implemented in the treatment of diabetes.
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The use of genetically altered laboratory animals offers a direct means to evaluate these alternative hypotheses in living systems and to probe aspects of the pathology of oxidative stress that are not readily amenable to other types of investigation. A particularly compelling illustration of the power of the approach is the study reported by Heinecke and associates in this issue of the JCI (13). They found that nitrotyrosine levels in peritoneal fluids from MPO-deficient mice infected with Klebsiella pneumoniae are markedly reduced relative to those from wild-type mice — this despite the induction of iNOS in both strains and a comparable accumulation of NO2–. By simultaneously measuring chlorotyrosine and nitrotyrosine in these fluids, the authors showed that active MPO is present in the peritoneum of the infected wild-type mice but not in the MPO knockout mice; specifically, the yields of the two tyrosine derivatives were comparable in the wild-type mice, but chlorotyrosine was completely lacking in the MPO knockouts. Since the tyrosine-nitrating and -chlorinating activities of MPO should be roughly comparable under the prevailing in vivo conditions, it follows that the large increase in nitrotyrosine yields measured in normal mice most likely arose by MPO catalysis, the unattractive alternative being that MPO somehow enabled expression of another as-yet unidentified nitration mechanism. Very similar conclusions have been reached by Hazen and collaborators, who compared nitrotyrosine accumulation in several acute inflammatory models that made use of MPO knockout and eosinophil peroxidase knockout mice (14). Other studies using knockouts to examine the role of MPO in tissue damage have not been so readily interpretable. In an earlier JCI publication, Heinecke and associates reported that LDL receptor- and MPO-deficient double-knockout mice were more susceptible to atherosclerosis than were littermates whose neutrophils contained normal MPO activity (15). Similarly, Takizawa and coworkers have recently reported that ischemia/reperfusion–induced cerebral damage was greater in MPO knockout than in wild-type mice and was accompanied by increased levels of nitration of protein tyrosyls (16). In both studies, MPO was apparently not present at the nitration sites. Numerous potential explanations (summarized in ref. 15) can be imagined for the apparent protection by MPO, although the actual mechanisms remain to be determined. An even more provocative study has involved use of mice deficient in neutrophil granule proteases, but with apparently normal oxidative capacities (17). These protease-deficient mice were unusually susceptible to infection by Staphylococcus aureus and Candida albicans, which was reflected in inefficient killing of these organisms by their isolated neutrophils. The authors of this study suggest that proteases are the central agents of microbicidal action, the primary purpose of respiratory activation being to electrogenically increase the intraphagosomal ionicity, thereby electrostatically triggering release of the proteases from inhibitory complexes with acid proteoglycans. MPO in this model is assigned the role of protecting the proteases from inactivation by H2O2 via catalatic degradation to O2 and H2O2.
Article
Peroxynitrite, a powerful mutagenic oxidant and nitrating species, is formed by the near diffusion-limited reaction of \cdot NO and O2{\cdot} during activation of phagocytes. Chronic inflammation induced by phagocytes is a major contributor to cancer and other degenerative diseases. We examined how γ -tocopherol (γ T), the principal form of vitamin E in the United States diet, and α -tocopherol (α T), the major form in supplements, protect against peroxynitrite-induced lipid oxidation. Lipid hydroperoxide formation in liposomes (but not isolated low-density lipoprotein) exposed to peroxynitrite or the \cdot NO and O2{\cdot} generator SIN-1 (3-morpholinosydnonimine) was inhibited more effectively by γ T than α T. More importantly, nitration of γ T at the nucleophilic 5-position, which proceeded in both liposomes and human low density lipoprotein at yields of ≈ 50% and ≈ 75%, respectively, was not affected by the presence of α T. These results suggest that despite α T's action as an antioxidant γ T is required to effectively remove the peroxynitrite-derived nitrating species. We postulate that γ T acts in vivo as a trap for membrane-soluble electrophilic nitrogen oxides and other electrophilic mutagens, forming stable carbon-centered adducts through the nucleophilic 5-position, which is blocked in α T. Because large doses of dietary α T displace γ T in plasma and other tissues, the current wisdom of vitamin E supplementation with primarily α T should be reconsidered.
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The effects on rat liver microsomal lipid peroxidation elicited by 2,2-dimethylchromenes and chromans structurally related to precocenes was investigated in NADPH-dependent incubations by using the thiobarbituric acid reactive substances (TBARS) and oxygen uptake rate tests as evaluation methods. Precocene II (1) exhibited an unexpected inhibitory activity on lipid peroxidation (IC50 = 11.4-mu-M, TBARS production test). Among the compounds tested, those which had a hydroxyl group on the aromatic ring, particularly at the C-6 position (i.e., 6-hydroxy-7-methoxy-2,2-dimethyl-1-2H-benzopyran (2) and its 3,4-dihydro derivative 5), appeared to be the best inhibitors. In this context, the inhibitory effect elicited by the hydroxychroman 5 (IC50 = 0.3-mu-M, TBARS production test) was higher than that shown by 2,6-di-tert-butyl-4-methylphenol (BHT, 11). These results suggested that the lipid peroxidation inhibitory effect exhibited by precocene II and related derivatives could be due to a vitamin E-like free radical scavenger based mechanism. The identification of phenolic metabolites in the incubations performed with precocene II or its benzopyranyl analogues lacking aromatic hydroxyl substituents supported the above postulated mechanism.
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The presence of stratum corneum carbonyls may serve as an intrinsic dosimeter for environmental oxidative damage to skin. To investigate the accumulation of carbonyls in human stratum corneum, skin was tape-stripped, then tapes were sequentially incubated with 2,4-dinitrophenyl hydrazine (DNPH), rat anti-DNP, mouse anti-rat IgG conjugated with alkaline phosphatase, p-nitrophenyl phosphate and absorbance (405 nm) measured and carbonyls estimated. Stratum corneum exposed in vitro to oxidants: hypochlorous acid (1, 10, 100 mM), ozone (0, 1, 5, 10 ppm for 2 h) or UV light (280-400 nm; 0, 4, 88, or 24 J/cm2) contained increased carbonyls. Furthermore, stratum corneum carbonyls were elevated in tanned compared with untanned sites: dorsal hand (0.43 +/- 0.06 nmol/cm2) vs. lower arm (0.32 +/- 0.04, mean +/- S.E.M., n = 11; P < 0.003) and lower back (0.26 +/- 0.02) vs. buttock (0.21 +/- 0.02; n = 6, P < 0.01) indicating in vivo oxidative damage.
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Cutaneous aging represents a complex situation in which at least two independent factors--innate aging and solar exposure--contribute to the development of degenerative changes in the dermis. The biochemical and ultrastructural evidence reviewed in this article indicates that reduced collagen deposition, as a result of diminished collagen biosynthesis and reduced proliferative capacity of the fibroblasts, could explain the development of dermal atrophy and would relate to poor wound healing in the elderly. At the same time, perturbations in the supramolecular organization of the elastic fiber network lead to alterations in the mechanical properties of the skin, as manifested by loose and sagging skin with reduced resilience and elasticity.
Article
Cutaneous aging represents a complex situation in which at least two independent factors--innate aging and solar exposure--contribute to the development of degenerative changes in the dermis. The biochemical and ultrastructural evidence reviewed in this article indicates that reduced collagen deposition, as a result of diminished collagen biosynthesis and reduced proliferative capacity of the fibroblasts, could explain the development of dermal atrophy and would relate to poor wound healing in the elderly. At the same time, perturbations in the supramolecular organization of the elastic fiber network lead to alterations in the mechanical properties of the skin, as manifested by loose and sagging skin with reduced resilience and elasticity.
Article
Peroxynitrite, formed by combination of superoxide radical with nitric oxide, is a reactive tissue-damaging species apparently involved in the pathology of several human diseases. Peroxynitrite nitrates tyrosine residues and inactivates alpha 1-antiproteinase. We show that both lipoic acid and dihydrolipoic acid efficiently protect against damage by peroxynitrite. By contrast, other disulphides tested did not. The biological antioxidant effects of lipoate/dihydrolipoate may involve scavenging of reactive nitrogen species as well as reactive oxygen species.
Article
Local intra-arterial infusion of high doses of nitric oxide (NO) donors, such as S-nitroso-N-acetyl-penicillamine or nitroprusside cause extensive gastric mucosal damage. The involvement of lipid peroxidation of mucosal tissue in the mechanism of such gastric damage has been investigated in the pentobarbitone-anaesthetised rat. Local intra-arterial infusion of nitroprusside (40 micrograms.kg-1.min-1) or S-nitroso-N-acetyl-penicillamine (40 micrograms.kg-1.min-1) induced macroscopically apparent injury and provoked a dose-dependent peroxidation of lipid in gastric tissue. By contrast, endothelin-1 infusion provoked mucosal injury of the mucosa, yet did not produce lipid peroxidation. Local co-infusion of superoxide dismutase (2000-4000 IU.kg-1) reduced both the lipid peroxidation and the mucosal damage provoked by S-nitroso-N-acetyl-penicillamine and nitroprusside. These findings indicate that lipid peroxidation accompanies the mucosal tissue damage induced by NO donors, while the action of superoxide dismutase implicates the involvement of peroxynitrite, formed from superoxide and NO, in this process.
Article
There is increasing evidence that aldehydes generated endogenously during lipid peroxidation contribute to the pathophysiologic effects associated with oxidative stress in cells and tissues. A number of reactive lipid aldehydes, such as 4-hydroxy-2-alkenals and malondialdehyde, have been implicated as causative agents in cytotoxic processes initiated by the exposure of biologic systems to oxidizing agents. Recently, acrolein (CH2 = CH-CHO), a ubiquitous pollutant in the environment, was identified as a product of lipid peroxidation reactions. The basis for this finding is an experimental approach that provides a measure of acrolein bound to lysine residues of protein. The identification of acrolein as an endogenous lipid-derived product suggests an examination of the possible role of this aldehyde as a mediator of oxidative damage in a variety of human diseases.
Article
Dopamine (DA) oxidation and the generation of reactive oxygen species (ROS) may contribute to the degeneration of dopaminergic neurons underlying various neurological conditions. The present study demonstrates that DA-induced cytotoxicity in differentiated PC12 cells is mediated by ROS and mitochondrial inhibition. Because cyanide induces parkinson-like symptoms and is an inhibitor of the antioxidant system and mitochondrial function, cells were treated with KCN to study DA toxicity in an impaired neuronal system. Differentiated PC12 cells were exposed to DA, KCN, or a combination of the two for 12-36 h. Lactate dehydrogenase (LDH) assays indicated that both DA (100-500 microM) and KCN (100-500 microM) induced a concentration- and time-dependent cell death and that their combination produced an increase in cytotoxicity. Apoptotic death, measured by Hoechst dye and TUNEL (terminal deoxynucleotidyltransferase dUTP nick end-labeling) staining, was also concentration- and time-dependent for DA and KCN. DA plus KCN produced an increase in apoptosis, indicating that KCN, and thus an impaired system, enhances DA-induced apoptosis. To study the mechanism(s) of DA toxicity, cells were pretreated with a series of compounds and incubated with DA (300 microM) and/or KCN (100 microM) for 24 h. Nomifensine, a DA reuptake inhibitor, rescued nearly 60-70% of the cells from DA- and DA plus KCN-induced apoptosis, suggesting that DA toxicity is in part mediated intracellularly. Pretreatment with antioxidants attenuated DA- and KCN-induced apoptosis, indicating the involvement of oxidative species. Furthermore, buthionine sulfoximine, an inhibitor of glutathione synthesis, increased the apoptotic response, which was reversed when cells were pretreated with antioxidants. DA and DA plus KCN produced a significant increase in intracellular oxidant generation, supporting the involvement of oxidative stress in DA-induced apoptosis. The nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester and the peroxynitrite scavenger uric acid blocked apoptosis and oxidant production, indicating involvement of nitric oxide. These results suggest that DA neurotoxicity is enhanced under the conditions induced by cyanide and involves both ROS and nitric oxide-mediated oxidative stress as an initiator of apoptosis.
Article
In this work we describe the development of specific markers for determination of both the membrane and intracellular damage induced by free radicals generated by UVB radiation (5-150 mJ/cm2) in cultured keratinocytes. This using simple, specific and sensitive fluorescent probes: cis-parinaric acid (PNA) to monitor membrane lipid peroxidation and 2',7'-dichloro-dihydrofluorescein diacetate (DCFH-DA) to evaluate the intracellular redox status, in parallel to the fluorimetric determination of the main intracellular antioxidant glutathione. To validate the methodologies, the changes in the intracellular oxidative status following exposure to low doses UVB were measured in both control and N-acetylcysteine-protected cells, in parallel with morphological analyses. UVB induces an early reduction of GSH inside the cell correlated with an increase in the intracellular peroxide content. The effects were time- and dose-dependent. In addition, using a sensitive fluorescent method, we quantitated the release of proteases, a family of proteolytic enzymes greatly involved in the onset/perpetuation of the free radical-induced skin damage from keratinocytes exposed to suberythemal UVB doses (5-15 mJ/cm2). The use of these fluorescent probes provides a reliable tool to detect the early signs of damage in keratinocyte cultures (when the apoptotic phenomenon has not yet been triggered) useful for future screening of protective molecules.
Article
The inhibitory effects of endogenous and synthetic compounds on the nitration and oxidation of L-tyrosine by peroxynitrite were examined. Nitration and oxidation activities of L-tyrosine by peroxynitrite were estimated by monitoring the formation of 3-nitrotyrosine and dityrosine with a high-performance liquid chromatography-ultraviolet (HPLC-UV)-fluorescence detector system. Glutathione and synthetic compounds ((2S,3R,4S)-N-ethylmercapto-3,4-dihydroxy-2-hydroxymethylpyrrolidine, L-N-dithiocarboxyproline) inhibited both the nitration and the oxidation reactions of L-tyrosine effectively. On the other hand, 5-methoxytryptamine and lipoic acid inhibited only the nitration reaction of L-tyrosine, and instead increased the oxidation reaction. It was assumed that 5-methoxytryptamine and lipoic acid reacted only with the nitrating species of peroxynitrite. This is the first report of a selective inhibitor for the nitrating reaction of peroxynitrite.
Article
Clues as to why long-lived species live so much longer than short-lived species may reside in the amount of reactive oxygen species (ROS) produced and their effect on damaging cell components (especially proteins) and alterations of crucial cellular processes. Rigorous evaluation of these concepts required critical comparisons of oxidative damage markers and/or parameters with assess difference in ROS flux and the critical age-modifying processes they influence. The limited experimental comparative results available implicate that ROS production per unit weight of total oxygen consumed is much less in the longer-lived species than in shorter-lived species. Mitochondria are the major site of ROS production. They are also the functional nexus for intracellular signaling thus modulating stress and growth factor mediated cellular survival, proliferation and apoptotic processes. Mitochondrial DNA mutations, perhaps caused by ROS, increase with age. Mutant mitochondria possess comparative replicative advantage, which leads to age-specific intracellular swarms. General inflammatory stress tends to increase with age. Disruption in coordinated cell-to-cell signaling triggered by alterations in intracellular signaling may be the basis of the age-related increases in tissue inflammation, which may explain some of the differences between long-lived species and short-lived species.
Article
Acrolein and 4-hydroxy-2-nonenal (HNE) are both byproducts of a lipid peroxidation reaction. Actinic elastosis in photodamaged skin of aged individuals is characterized by the accumulation of fragmented elastic fibers in the sun-exposed areas. To study whether a lipid peroxidation reaction is involved in the accumulation of altered elastic fibers in actinic elastosis, skin specimens obtained from sun-damaged areas were immunohistochemically examined using the antibodies against acrolein and HNE. Both antibodies were found to react with the accumulations of elastic material. Double immunofluorescence labeling demonstrated that acrolein/elastin and HNE/elastin were colocalized in the actinic elastosis. Western blot analysis showed that the polypeptide with a molecular weight of 62 kDa reacted with anti-acrolein, anti-HNE and anti-elastin antibodies. The results suggest that acrolein and HNE may be associated with actinic elastosis.
Article
Glycolaldehyde, an intermediate of the Maillard reaction, and fructose, which is mainly derived from the polyol pathway, rapidly inactivate human Cu,Zn-superoxide dismutase (SOD) at the physiological concentration. We employed this inactivation with these carbonyl compounds as a model glycation reaction to investigate whether carnosine and its related compounds could protect the enzyme from inactivation. Of eight derivatives examined, histidine, Gly-His, carnosine and Ala-His inhibited the inactivation of the enzyme by fructose (p<0.001), and Gly-His, Ala-His, anserine, carnosine, and homocarnosine exhibited a marked protective effect against the inactivation by glycolaldehyde (p<0.001). The carnosine-related compounds that showed this highly protective effect against the inactivation by glycolaldehyde had high reactivity with glycolaldehyde and high scavenging activity toward the hydroxyl radical as common properties. On the other hand, the carnosine-related compounds that had a protective effect against the inactivation by fructose showed significant hydroxyl radical-scavenging ability. These results indicate that carnosine and such related compounds as Gly-His and Ala-His are effective anti-glycating agents for human Cu,Zn-SOD and that the effectiveness is based not only on high reactivity with carbonyl compounds but also on hydroxyl radical scavenging activity.
Article
Recent discoveries in the biology of nitrosating agents, such as S-nitrosoglutathione (GSNO), have revealed that several proteins are particularly susceptible to S-nitrosation at specific cysteine residues. In searching for consensus nitrosation sites, it has been suggested that there are both hydrophobic and acid-base motifs in target proteins adjacent to the site of their modification (56). GSNO, a commonly used exogenous nitrosating agent, has been detected in vivo at micromolar concentrations in brain tissue and can directly transfer NO equivalents to target protein thiols (8). Additionally, other mechanisms of S-nitrosation of nucleophilic cysteines (e.g., by N2O3) are plausible (8). S-nitrosothiols in proteins can react with free sulfhydryl groups to create disulfide bonds and can be reduced by various reductants (8). Although the chemical pathways through which nitric oxide forms S-nitrosocysteine are complex, experiments using induced expression of NO synthase isoforms and neuronal NO synthase knockout cells have established that NO production increases levels of overall protein S-nitrosation (57, 58). S-nitrosation of proteins is potentially a key method that cells use to mediate inflammatory responses and other NO-regulated processes. Proteome-wide screening for modified proteins promises to be an exciting area of research in the immediate future. High-throughput methods have recently been developed for examining global protein S-nitrosation, glutathionylation, and tyrosine nitration (57, 93, 94). Although most current methods use the power of mass spectrometry for identification of proteins, the approaches taken to enrich for and isolate modified proteins differ. For example, an elegant approach to the isolation of S-nitrosated proteins was recently reported (57). Free thiol groups were reacted with methyl methanethiosulfonate, and then S-NO groups were reduced to free thiols by treatment with ascorbate. Subsequently, using streptavidin agarose beads, the newly released protein thiols were converted to biotin conjugates to enrich for proteins. Peptides from isolated proteins were identified using matrix-assisted laser desorption ionization mass spectrometry. Approximately 15–20 proteins were identified as targets of nitrosating agents. The methodology was validated by confirmation that many targets of exogenous nitrosating agents are in vivo targets, as revealed by the lack of labeling in brain lysates from mice deficient in neuronal NO synthase.
Article
The notion that oxidative stress contributes to the pathogenesis of vascular disease was originally driven by observations that low-density lipoprotein (LDL) modification is a prominent feature of atherosclerosis. More recently, it has become clear that the relation between oxidative stress and vascular disease goes beyond LDL oxidation and involves cellular production of reactive oxygen species (ROS). Considerable data now indicate that ROS represent an important means of cellular signaling, although the precise mechanisms whereby ROS accomplish this function remain unclear. Emerging data point to protein thiol groups as important targets for post-translational protein modification by ROS. In this review, the data linking ROS to cell signaling is discussed and the notion that ROS mediate a vascular "injury" response is proposed.
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The anatomy and functions of the blood and lymph vessels of human skin are described. Variation in these due to site, ageing and events during life consequent to exposure to a threatening environment are emphasised. Gradual atrophy and greater heterogeneity are features of ageing. Responses to injury and repair are complex and the interaction of mechanical signals distorting skin cells with numerous chemical signals are referred to. The lymphatics are part of an immunosurveillance system to monitor skin barrier penetration. The review attempts to draw attention to key recent advances in our understanding of the cytokine and growth factor production of the skin in the context of previous mainly physiological reviews especially influenced by 50 years of clinical practice as a dermatologist with an eye on both the skin and the fields of microcirculation and lymphology.
Article
Multiple lines of evidence demonstrate that oxidative stress is an early event in Alzheimer's disease (AD), occurring prior to cytopathology, and therefore may play a key pathogenic role in the disease. Indeed, that oxidative mechanisms are involved in the cell loss and other neuropathology associated with AD is evidenced by the large number of metabolic signs of oxidative stress as well as by markers of oxidative damage. However, what is intriguing is that oxidative damage decreases with disease progression, such that levels of markers of rapidly formed oxidative damage, which are initially elevated, decrease as the disease progresses to advanced AD. This finding, along with the compensatory upregulation of antioxidant enzymes found in vulnerable neurons in AD, indicates that reactive oxygen species (ROS) not only cause damage to cellular structures but also provoke cellular responses. Mammalian cells respond to extracellular stimuli by transmitting intracellular instructions by signal transduction cascades to coordinate appropriate responses. Therefore, not surprisingly stress-activated protein kinase (SAPK) pathways, pathways that are activated by oxidative stress, are extensively activated during AD. In this paper, we review the evidence of oxidative stress and compensatory responses that occur in AD with a particular focus on the roles and mechanism of activation of SAPK pathways.
Article
The effects of peroxynitrite on hyaluronan has been studied by using an integrated spectroscopical approach, namely electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and mass spectrometry (MS). The reaction has been performed with the polymer, the tetrasaccharide oligomer as well as with the monosaccharides N-acetylglucosamine and glucuronic acid. The outcome of the presence of molecular oxygen and carbon dioxide has been also evaluated. Although 1H-NMR and ESI-MS experiments did not revealed peroxynitrite-mediated modification of hyaluronan as well as of related saccharides, from spin-trapping EPR experiments it was concluded that peroxynitrite induce the formation of C-centered carbon radicals, most probably by the way of its hydroxyl radical-like reactivity. These EPR data support the oxidative pathway involved in the degradation of hyaluronan, a probable event in the development and progression of rheumatoid arthritis.
Article
Skin aging appears to be the result of both scheduled and continuous "wear and tear" processes that damage cellular DNA and proteins. Two types of aging, chronological skin aging and photoaging, have distinct clinical and histological features. Chronological skin aging is a universal and inevitable process characterized primarily by physiologic alterations in skin function. In this case, keratinocytes are unable to properly terminally differentiate to form a functional stratum corneum, and the rate of formation of neutral lipids that contribute to the barrier function slows, causing dry, pale skin with fine wrinkles. In contrast, photoaging results from the UVR of sunlight and the damage thus becomes apparent in sun-exposed skin. Characteristics of this aging type are dry and sallow skin displaying fine wrinkles as well as deep furrows, resulting from the disorganization of epidermal and dermal components associated with elastosis and heliodermatitis. Understanding of the functions of the skin and the basic principles of moisturizer use and application is important for the prevention of skin aging. Successful treatment of dry skin with appropriate skin care products gives the impression of eternal youth.
Article
Fighting skin ageing is one of the major targets of cosmetology research. However, traditional approaches to skin ageing using stimulation of basal keratinocyte proliferation and fibroblastic neosynthesis appear today to be incomplete, particularly considering changes occurring at the dermal-epidermal junction (DEJ) during the course of ageing. Unfortunately, the lack of in vitro model limits the exploration process of the phenomena of DEJ ageing, and particularly the evaluation of the changes of key components, that are laminin-5, types IV and VII collagens. The aim of this work was to provide an in vitro model of reconstructed skin, base for new dosage and identification methods for qualitative and quantitative analysis of the key components of DEJ. Reverse transcriptase-polymerase chain reaction (RT-PCR) and quantitative RT-PCR were successfully applied to this model to analyse mRNA of laminin-5, types IV and VII collagens and their variation in 'young' and 'mature' reconstructed skin model. Finally, this model was used to test the activity of ingredients for cosmetic application, in order to modulate the expression of the major components of DEJ. To conclude, we demonstrated that this in vitro model of reconstructed young and mature skin provides a useful tool to get into the biology of the DEJ, key structure of the skin, and specifically into its dynamic changes during the ageing process.
Article
The occurrence of protein tyrosine nitration under disease conditions is now firmly established and represents a shift from the signal transducing physiological actions of (.)NO to oxidative and potentially pathogenic pathways. Tyrosine nitration is mediated by reactive nitrogen species such as peroxynitrite anion (ONOO(-)) and nitrogen dioxide ((.)NO2), formed as secondary products of (.)NO metabolism in the presence of oxidants including superoxide radicals (O2(.-)), hydrogen peroxide (H2O2), and transition metal centers. The precise interplay between (.)NO and oxidants and the identification of the proximal intermediate(s) responsible for nitration in vivo have been under controversy. Despite the capacity of peroxynitrite to mediate tyrosine nitration in vitro, its role on nitration in vivo has been questioned, and alternative pathways, including the nitrite/H2O2/hemeperoxidase and transition metal-dependent mechanisms, have been proposed. A balanced analysis of existing evidence indicates that (i) different nitration pathways can contribute to tyrosine nitration in vivo, and (ii) most, if not all, nitration pathways involve free radical biochemistry with carbonate radicals (CO3(.-)) and/or oxo-metal complexes oxidizing tyrosine to tyrosyl radical followed by the diffusion-controlled reaction with (.)NO2 to yield 3-nitrotyrosine. Although protein tyrosine nitration is a low-yield process in vivo, 3-nitrotyrosine has been revealed as a relevant biomarker of (.)NO-dependent oxidative stress; additionally, site-specific nitration focused on particular protein tyrosines may result in modification of function and promote a biological effect. Tissue distribution and quantitation of protein 3-nitrotyrosine, recognition of the predominant nitration pathways and individual identification of nitrated proteins in disease states open new avenues for the understanding and treatment of human pathologies.
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