Age-related changes in oxidative damage to lipids and DNA in rat skin

Cholesterol is more readily oxidized than phospholipid linoleates in cell membranes to produce cholesterol hydroperoxides

Cholesterol is an essential component of cell membranes and serves as an important precursor of steroidal hormones and bile acids, but elevated levels of cholesterol and its oxidation products have been accepted as a risk factor for maintenance of health. The free and ester forms of cholesterol and fatty acids are the two major biological lipids. The aim of this hypothesis paper is to address the long-standing dogma that cholesterol is less susceptible to free radical peroxidation than polyunsaturated fatty acids (PUFAs). It has been observed that cholesterol is peroxidized much slower than PUFAs in plasma but that, contrary to expectations from chemical reactivity toward peroxyl radicals, cholesterol appears to be more readily autoxidized than linoleates in cell membranes. The levels of oxidation products of cholesterol and linoleates observed in humans support this notion. It is speculated that this discrepancy is ascribed to the fact that cholesterol and phospholipids bearing PUFAs are localized apart in raft and non-raft domains of cell membranes respectively and that the antioxidant vitamin E distributed predominantly in the non-raft domains cannot suppress the oxidation of cholesterol lying in raft domains which are relatively deficient in antioxidant.

Modulation of Oxidative Status by Normoxia and Hypoxia on Cultures of Human Dermal Fibroblasts: How Does It Affect Cell Aging?

Reactive oxygen species (ROS) production in the skin is among the highest compared to other organs, and a clear correlation exists between ROS production and skin aging. Many attempts are underway to reduce oxidative stress in the skin by topical treatment or supplementation with antioxidants/cosmeceuticals, and cultures of human dermal fibroblasts (HDF) are widely used for these studies. Here, we examined the influence of oxygen tension on cell aging in HDF and how this impacted ROS production, the enzymatic and nonenzymatic antioxidant response system, and the efficacy of this defense system in limiting DNA damage and in modulating gene expression of proteins involved in the extracellular matrix, linked to skin aging. We investigated a selection of parameters that represent and reflect the behavior of cellular responses to aging and oxygen tension. Serial passaging of HDF under normoxia (21%) and hypoxia (5%) leads to cell aging as confirmed by β-galactosidase activity, p16 expression, and proliferation rate. However, in HDF under 21% O₂, markers of aging were significantly increased compared to those under 5% O₂ at matched cell passages despite having lower levels of intracellular ROS and higher levels of CoQ₁₀, total GSH, SOD1, SOD3, and mitochondrial superoxide anion. miRNA-181a, which is known to be upregulated in HDF senescence, was also analyzed, and indeed, its expression was significantly increased in old cells at 21% O₂ compared to those at 5% O₂. Upregulation of MMP1 and downregulation of COL1A1 along with increased DNA damage were also observed under 21% O₂ vs 5% O₂. The data highlight that chronic exposure to atmospheric 21% O₂ is able to trigger hormetic adaptive responses in HDF that however fail, in the long term, to prevent cellular aging. This information could be useful in further investigating molecular mechanisms involved in adaptation of skin fibroblasts to oxidative stress and may provide useful hints in addressing antiaging strategies.

Early fragmentation of polyester urethane sheet neither causes persistent oxidative stress nor alters the outcome of normal tissue healing in rat skin

Silicone breast implant is associated with complications inherent to the surgical procedure. Prosthesis coating with polyurethane, however, commonly reduces the incidence of such complications. In this paper, the authors evaluated the inflammatory histomorphometric profile and oxidative damage associated to the implant of polyester urethane sheets. Forty-eight Wistar rats were divided into Sham or polyester urethane groups (n = 8/group) and underwent a polyester urethane implant in the dorsal skinfold. Tissue samples were collected on days seven, 30, and 90 after surgery and subjected to histomorphometric analysis and biochemical tests. Results were analyzed by one-way ANOVA (p ≤ 0.05). Peri-implant tissue samples exhibited characteristic inflammatory response associated with the biomaterial, with increased vascularization on day seven and augmented levels of IL1-b and TNF-a after 30 days. Peri-implant fibrocystic population was small on day seven, but increased considerably after 90 days. A rise in the carbonyl group levels of skin samples in the polyester urethane group was observed on day seven. Findings suggest that polyester urethane sheets undergo biodegradation at an early stage after implantation, followed by increased vascularity and microencapsulation of biomaterial fragments, without persistent oxidative damage. Fiber arrangement inside the collagen matrix results in a fibrotic scar because of polyester urethane degradation.

Protective effect of gelatin peptides from pacific cod skin against photoaging by inhibiting the expression of MMPs via MAPK signaling pathway

Chronic exposure to ultraviolet (UV) irradiation causes skin photoaging. This study was undertaken to identify the anti-photoaging mechanisms of gelatin hydrolysate (CH) derived from pacific cod skin. Quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) and ELISA assays were used to investigate the effects of CH on matrix metalloproteinases (MMPs) and the signaling pathways after UV irradiation by using a mice skin photoaging model. The average molecular weight of CH was 1200Da, and 273/1000 residues were hydrophobic, Gly-Pro and Gly-Leu sequences and Arg at C-terminus appeared frequently in CH. CH improved pathological changes of collagen fibers and significantly inhibited collagen content reduction in photoaging skin. Moreover, CH blocked the up-regulated expression of interstitial collagenase (MMP-1), stromelysin 1 (MMP-3), and gelatinase (MMP-9) in photoaging skin. Besides, CH suppressed the activities of MMPs by increasing the contents of tissue inhibitors of matrix metalloproteinases (TIMPs). CH significantly reduced the UV irradiation-dependent up-regulated phosphorylation of ERK and p38 in the mitogen-activated protein kinase (MAPK) signaling pathway. Furthermore, it inhibited the activation of activator protein 1 (AP-1) by down-regulating the mRNA level of c-Jun and c-Fos, which are the two transcription factors responsible for the regulation of MMPs expression. CH can effectively protect against UV irradiation-induced skin photoaging by inhibiting the expression and the activity of MMPs.

Comparison of Glutathione, Cysteine, and Their Redox Potentials in the Plasma of Critically Ill and Healthy Children

BACKGROUND

Oxidative stress is known to play a role in critical illness due to an imbalance in reactive oxygen species and reactive nitrogen species, and the body's ability to detoxify pro-oxidants using small molecule anti-oxidants and anti-oxidant enzymes.

OBJECTIVE

To compare the concentrations of plasma redox metabolites and redox potentials for the Cys/CySS and GSH/GSSG thiol/disulfide pairs in critically ill children with healthy control children.

METHODS

We performed a prospective clinical observational study of children ages ≤18 years and weight ≥6 kg, who were hospitalized between January 2010 and April 2012 in a 30-bed multidisciplinary medical-surgical pediatric intensive care unit (PICU). We measured the plasma concentrations of Cys, CySS, GSH, and GSSG within the first 24 h of PICU arrival, and we calculated the redox potential for the Cys/CySS (Eh Cys/CySS) and GSH/GSSG (Eh GSH/GSSG) thiol/disulfide pairs in the plasma of 61 critically ill children and 16 healthy control children.

RESULTS

Critically ill children have less Cys (p = 0.009), less CySS (p = 0.011), less Total Cys ([Cys] + 2[CySS], p = 0.01), more GSSG (p < 0.001), and more oxidized Eh GSH/GSSG (p < 0.001) compared to healthy children.

CONCLUSION

Our results demonstrate that in the presence of pediatric critical illness, the Total Cys/CySS thiol pool decreases while GSH is likely one component of the cellular redox system that reduces CySS back to Cys, thus maintaining Eh Cys/CySS. The Total Cys pool is more abundant than the Total GSH pool in the plasma of children. Further investigation is needed to elucidate the differences in redox potentials in subgroups of critically ill children, and to determine whether differences in redox metabolite concentrations and redox potentials correlate with severity of critical illness and clinical outcomes.

Inhalation toxicology methods: the generation and characterization of exposure atmospheres and inhalational exposures

In this unit, the need for laboratory-based inhalation toxicology studies, the historical background on adverse health effects of airborne toxicants, and the benefits of advance planning for the building of analytic options into the study design to maximize the scientific gains to be derived from the investments in the study are outlined. The following methods are described: (1) the generation and characterization of exposure atmospheres for inhalation exposures in humans and laboratory animals; (2) the delivery and distribution into and within whole-body exposure chambers, head-only exposure chambers, face-masks, and mouthpieces or nasal catheters; (3) options for on-line functional assays during and between exposures; and (4) options for serial non-invasive assays of response. In doing so, a description beyond exposures to single agents and simple mixtures is presented, and included are methods for evaluating biological responses to complex environmental mixtures. It is also emphasized that great care should be taken in the design and execution of such studies so that the scientific returns can be maximized both initially, and in follow-up utilization of archived samples of the exposure atmospheres, excreta, and tissues collected for histology.

Chronic caloric restriction partially protects against age-related alteration in serum metabolome

Calorie restriction (CR) remains the most robust metabolic intervention to extend lifespan and improve healthspan in several species. Using global and targeted mass spectrometry-based metabolomics approaches, here we show that chronic CR prevents age-related changes in specific metabolic signatures. Global metabolomic analysis using ultra-performance liquid chromatography-tandem mass spectrometry detected more than 7,000 metabolites in sera from ad-libitum-fed young, aged, and aged C57BL/6 mice maintained on 40 % CR. Multivariate statistical analysis of mass spectrometry data revealed a clear separation among the young, aged, and aged-CR mice demonstrating the potential of this approach for producing reliable metabolic profiles that discriminate based on age and diet. We have identified 168 discriminating features with high statistical significance (p ≤ 0.001) and validated and quantified three of these metabolites using targeted metabolite analysis. Calorie restriction prevented the age-related alteration in specific metabolites, namely lysophosphatidylcholines (16:1 and 18:4), sphingomyelin (d18:1/12:0), tetracosahexaenoic acid, and 7α-dihydroxy-4-cholesten-3-one, in the serum. Pathway analysis revealed that CR impacted the age-related changes in metabolic byproducts of lipid metabolism, fatty acid metabolism, and bile acid biosynthesis. Our data suggest that metabolomics approach has the potential to elucidate the metabolic mechanism of CR's potential anti-aging effects in larger-scale investigations.

Astaxanthin modulates age-associated mitochondrial dysfunction in healthy dogs

Young (2.97±0.01 yr; 8.16±0.15 kg BW) and geriatric (10.71±0.01 yr; 9.46±0.18 kg BW) healthy female Beagle dogs (n=14/age group) were fed 0 or 20 mg astaxanthin daily for 16 wk to examine modulation of mitochondrial function. Fasted blood was sampled on wk 0, 8, and 16. Mitochondria membrane permeability, ATP production, cytochrome c oxidase/reductase, and number were assessed in leukocytes whereas astaxanthin uptake, glutathione, superoxide dismutase, nitric oxide, 8-hydroxy-2'-deoxyguanosine, 8-isoprostane, and protein carbonyl were measured in plasma. Aging increased (P<0.05) complex III cytochrome c oxidoreductase but decreased (P<0.05) 8-hydroxy-2'-deoxyguanosine and protein carbonyl. Mitochondrial function improved in both young and geriatric dogs by increasing (P<0.05) ATP production, mitochondria mass, and cytochrome c oxidoreductase activity, especially in geriatric dogs compared with young dogs. Astaxanthin feeding also increased (P<0.05) the reduced glutathione to oxidized glutathione ratio in young dogs and decreased (P<0.05) nitric oxide in both young and geriatric dogs. Dietary astaxanthin improved mitochondrial function in blood leukocytes, most likely by alleviating oxidative damage to cellular DNA and protein.

Modulation of collagen synthesis and its gene expression in human skin fibroblasts by tocotrienol-rich fraction

INTRODUCTION

Skin aging may occur as a result of increased free radicals in the body. Vitamin E, the major chain-breaking antioxidant, prevents propagation of oxidative stress, especially in biological membranes. In this study, the molecular mechanism of tocotrienol-rich fraction (TRF) in preventing oxidative stress-induced skin aging was evaluated by determining the rate of total collagen synthesis and its gene expression in human skin fibroblasts.

MATERIAL AND METHODS

Primary culture of human skin fibroblasts was derived from circumcision foreskin of 9 to 12 year-old boys. Fibroblast cells were divided into 5 different treatment groups: untreated control, hydrogen peroxide (H(2)O(2))-induced oxidative stress (20 µM H(2)O(2) exposure for 2 weeks), TRF treatment, and pre- and post-treatment of TRF to H(2)O(2)-induced oxidative stress.

RESULTS

Our results showed that H(2)O(2)-induced oxidative stress decreased the rate of total collagen synthesis and down-regulated COL I and COL III in skin fibroblasts. Pre-treatment of TRF protected against H(2)O(2)-induced oxidative stress as shown by increase in total collagen synthesis and up-regulation of COL I and COL III (p<0.05) genes. However, similar protective effects against H(2)O(2)-induced oxidative stress were not observed in the post-treated fibroblasts.

CONCLUSIONS

Tocotrienol-rich fraction protects against H(2)O(2)-induced oxidative stress in human skin fibroblast culture by modulating the expression of COL I and COL III genes with concomitant increase in the rate of total collagen synthesis. These findings may indicate TRF protection against oxidative stress-induced skin aging.

Age- and sun exposure-dependent differences in 8-hydroxy-2'-deoxyguanosine and N-(carboxymethyl)lysine in human epidermis

Aging and exposure to sunlight are two major factors in the deterioration of skin function. In this study, thirty-six fixed human skin samples from sun-exposed and unexposed areas from young and old individuals were used to evaluate the localization of oxidative stress according to levels and distribution of 8-hydroxy-2'-deoxyguanosine and N^ε-(carboxymethyl)lysine in samples using immunohistochemistry. In the epidermis of the young, negligible amounts of 8-hydroxy-2'-deoxyguanosine and N^ε-(carboxymethyl)lysine were detected in unexposed areas, whereas nuclear 8-hydroxy-2'-deoxyguanosine and cytoplasmic N^ε-(carboxymethyl)lysine were increased in the lower epidermis in sun-exposed areas. In contrast, the aged presented prominent nuclear 8-hydroxy-2'-deoxyguanosine and nuclear N^ε-(carboxymethyl)lysine in the epidermis of unexposed areas, concomitant with dermal increase in N^ε-(carboxymethyl)lysine. However, the immunostaining of 8-hydroxy-2'-deoxyguanosine and N^ε-(carboxymethyl)lysine revealed a decrease in the epidermis of sun-exposed areas in the aged. These results suggest an age-dependent difference in the adaptation and protective mechanisms of the epidermis against sunlight-associated oxidative stress, thus necessitating distinct standards for evaluation in each age group. Further investigation is warranted to elucidate underlying molecular mechanisms.

Tocotrienol-rich fraction prevents cell cycle arrest and elongates telomere length in senescent human diploid fibroblasts

This study determined the molecular mechanisms of tocotrienol-rich fraction (TRF) in preventing cellular senescence of human diploid fibroblasts (HDFs). Primary culture of HDFs at various passages were incubated with 0.5 mg/mL TRF for 24 h. Telomere shortening with decreased telomerase activity was observed in senescent HDFs while the levels of damaged DNA and number of cells in G(0)/G(1) phase were increased and S phase cells were decreased. Incubation with TRF reversed the morphology of senescent HDFs to resemble that of young cells with decreased activity of SA-β-gal, damaged DNA, and cells in G(0)/G(1) phase while cells in the S phase were increased. Elongated telomere length and restoration of telomerase activity were observed in TRF-treated senescent HDFs. These findings confirmed the ability of tocotrienol-rich fraction in preventing HDFs cellular ageing by restoring telomere length and telomerase activity, reducing damaged DNA, and reversing cell cycle arrest associated with senescence.

The protective effects of long-term oral administration of marine collagen hydrolysate from chum salmon on collagen matrix homeostasis in the chronological aged skin of Sprague-Dawley male rats

To investigate the long-term effects of marine collagen hydrolysate (MCH) from Chum Salmon skin on the aberrant collagen matrix homeostasis in chronological aged skin, Sprague-Dawley male rats of 4-wk-old were orally administrated with MCH at the diet concentrations of 2.25% and 4.5% for 24 mo. Histological and biochemical analysis revealed that MCH had the potential to inhibit the collagen loss and collagen fragmentation in chronological aged skin. Based on immunohistochemistry and western blot analysis, collagen type I and III protein expression levels in MCH-treated groups significantly increased as compared with the aged control group. Furthermore, quantitative real-time polymerase chain reaction and western blot analysis showed MCH was able to increase the expressions of procollagen type I and III mRNA (COL1A2 and COL3A1) through activating Smad signaling pathway with up-regulated TGF-βRII (TβRII) expression level. Meanwhile, MCH was shown to inhibit the age-related increased collagen degradation through attenuating MMP-1 expression and increasing tissue inhibitor of metalloproteinases-1 expression in a dose-dependent manner. Moreover, MCH could alleviate the oxidative stress in chronological aged skin, which was revealed from the data of superoxide dismutase activity and the thiobarbituric acid reactive substances level in skin homogenates. Therefore, MCH was demonstrated to have the protective effects on chronological skin aging due to the influence on collagen matrix homeostasis. And the antioxidative property of MCH might play an important role in the process.

Sterol regulatory element-binding protein (SREBP)-1-mediated lipogenesis is involved in cell senescence

Increased cell mass is one of the characteristics of senescent cells, but this event has not been clearly defined. When subcellular organellar mass was estimated with organelle-specific fluorescence dyes, we observed that most membranous organelles progressively increase in mass during cell senescence. This increase was accompanied by an increase in membrane lipids and augmented expression of lipogenic enzymes, such as fatty acid synthase (FAS), ATP citrate lyase, and acetyl-CoA carboxylase. The mature form of sterol regulatory element-binding protein (SREBP)-1 was also elevated. Increased expression of these lipogenic effectors was further observed in the liver tissues of aging Fischer 344 rats. Ectopic expression of mature form of SREBP-1 in both Chang cells and primary young human diploid fibroblasts was enough to induce senescence. Blocking lipogenesis with FAS inhibitors (cerulenin and C75) and via siRNA-mediated silencing of SREBP-1 and ATP citrate lyase significantly attenuated H(2)O(2)-induced senescence. Finally, old human diploid fibroblasts were effectively reversed to young-like cells by challenging with FAS inhibitors. Our results suggest that enhanced lipogenesis is not only a common event, but also critically involved in senescence via SREBP-1 induction, thereby contributing to the increase in organelle mass (as a part of cell mass), a novel indicator of senescence.

Ginsenoside-Rd attenuates oxidative damage related to aging in senescence-accelerated mice

Among the various theories of the aging process, the free radical theory, which proposes that deleterious actions of free radicals are responsible for the functional deterioration associated with aging, has received widespread attention. The theory suggests that enhancement of the antioxidative defence system to attenuate free-radical-induced damage will counteract the aging process. We used senescence-accelerated mice (SAM) to investigate the relationship between aging and the antioxidative defence system and evaluated the effects of ginsenoside-Rd, the saponin from ginseng, by measuring antioxidative defence system parameters, including the glutathione (GSH)/glutathione disulfide (GSSG) redox status, antioxidative enzyme activity and level of lipid peroxidation. SAM at 11 months of age (old SAM) showed a significantly lower hepatic GSH/GSSG ratio, due to decreased GSH and increased GSSG levels, than SAM at 5 weeks of age (young SAM). However, the administration of ginsenoside-Rd at a dose of 1 or 5 mg kg−1 daily for 30 days to 10-month-old SAM significantly increased GSH, but decreased GSSG, resulting in elevation of the GSH/GSSG ratio. In addition, ginsenoside-Rd increased the activity of glutathione peroxidase (GSH-Px) and glutathione reductase that were both significantly lower in old SAM than in young SAM. This suggests that ginsenoside-Rd could play a crucial role in enhancing the defence system through regulation of the GSH/GSSG redox status. Moreover, decreases in the superoxide dismutase (SOD) and catalase activity in old SAM compared with young SAM were also revealed, indicating that the aging process resulted in suppression of the antioxidative defence system. However, ginsenoside-Rd did not affect SOD and catalase activity. As catalase is localized in peroxisome granules and GSH-Px is present in the cytoplasm and mitochondrial matrix, the site of ginsenoside-Rd action may be the cytoplasm and mitochondrial matrix. Furthermore, the serum and liver malondialdehyde levels, indicators of lipid peroxidation, were elevated with aging, while ginsenoside-Rd inhibited lipid peroxidation. This study indicates that the aging process leads to suppression of the antioxidative defence system and accumulation of lipid peroxidation products, while ginsenoside-Rd attenuates the oxidative damage, which may be responsible for the intervention of GSH/GSSG redox status.

Reactive oxygen intermediate-induced pathomechanisms contribute to immunosenescence, chronic inflammation and autoimmunity

Deregulation of reactive oxygen intermediates (ROI) resulting in either too high or too low concentrations are commonly recognized to be at least in part responsible for many changes associated with aging. This article reviews ROI-dependent mechanisms critically contributing to the decline of immune function during physiologic - or premature - aging. While ROI serve important effector functions in cellular metabolism, signalling and host defence, their fine-tuned generation declines over time, and ROI-mediated damage to several cellular components and/or signalling deviations become increasingly prevalent. Although distinct ROI-associated pathomechanisms contribute to immunosenescence of the innate and adaptive immune system, mutual amplification of dysfunctions may often result in hyporesponsiveness and immunodeficiency, or in chronic inflammation with hyperresponsiveness/deregulation, or both. In this context, we point out how imbalanced ROI contribute ambiguously to driving immunosenescence, chronic inflammation and autoimmunity. Although ROI may offer a distinct potential for therapeutic targeting along with the charming opportunity to rescue from deleterious processes of aging and chronic inflammatory diseases, such modifications, owing to the complexity of metabolic interactions, may carry a marked risk of unforeseen side effects.

Clinical pharmacology and therapeutic use of antioxidant vitamins

The clinical use of antioxidants has gained considerable interest during the last decade. It was suggested from epidemiological studies that diets high in fruits and vegetables might help decrease the risk of cardiovascular disease. Therefore, supplements of vitamins C and E were applied through protocols aimed to prevent diseases such as atherosclerosis, preeclampsia or hypertension, thought to be mediated by oxidative stress. Despite the biological properties of these vitamins could account for an effective protection, as shown by several clinical and experimental studies, their efficacy remains controversial in the light of some recent clinical trials and meta-analyses. However, the methodology of these studies, criteria for selection of patients, the uncertain extent of progression of the disease when initiating supplementation, the lack of mechanistic studies containing basic scientific aspects, such as the bioavailability, pharmacokinetic properties, and the nature of the antioxidant sources of vitamins, could account for the inconsistency of the various clinical trials and meta-analyses assessing the efficacy of these vitamins to prevent human diseases. This review presents a survey of the clinical use of antioxidant vitamins E and C, proposing study models based on the biological effects of these compounds likely to counteract the pathophysiological mechanisms able to explain the structural and functional organ damage.

Large-scale optimization-based classification models in medicine and biology

We present novel optimization-based classification models that are general purpose and suitable for developing predictive rules for large heterogeneous biological and medical data sets. Our predictive model simultaneously incorporates (1) the ability to classify any number of distinct groups; (2) the ability to incorporate heterogeneous types of attributes as input; (3) a high-dimensional data transformation that eliminates noise and errors in biological data; (4) the ability to incorporate constraints to limit the rate of misclassification, and a reserved-judgment region that provides a safeguard against over-training (which tends to lead to high misclassification rates from the resulting predictive rule); and (5) successive multi-stage classification capability to handle data points placed in the reserved-judgment region. To illustrate the power and flexibility of the classification model and solution engine, and its multi-group prediction capability, application of the predictive model to a broad class of biological and medical problems is described. Applications include: the differential diagnosis of the type of erythemato-squamous diseases; predicting presence/absence of heart disease; genomic analysis and prediction of aberrant CpG island meythlation in human cancer; discriminant analysis of motility and morphology data in human lung carcinoma; prediction of ultrasonic cell disruption for drug delivery; identification of tumor shape and volume in treatment of sarcoma; discriminant analysis of biomarkers for prediction of early atherosclerois; fingerprinting of native and angiogenic microvascular networks for early diagnosis of diabetes, aging, macular degeneracy and tumor metastasis; prediction of protein localization sites; and pattern recognition of satellite images in classification of soil types. In all these applications, the predictive model yields correct classification rates ranging from 80 to 100%. This provides motivation for pursuing its use as a medical diagnostic, monitoring and decision-making tool.

Mitochondrial ageing and the beneficial role of alpha-lipoic acid

Oxidative damage has been implicated to be a major causative factor in the decline in physiological functions that occur during the ageing process. Mitochondria are known to be a rich source for the production of free radicals and, consequently, mitochondrial components are susceptible to lipid peroxidation (LPO) that decreases respiratory activity. In the present investigation, we have evaluated mitochondrial LPO, 8-oxo-dG, oxidized glutathione, reduced glutathione, ATP, lipoic acid, TCA cycle enzymes and electron transport chain (ETC) complex activities in the brain of young versus aged rats. In aged rats, the contents of LPO, oxidized glutathione and 8-oxo-dG were high whereas reduced glutathione, ATP, lipoic acid, TCA cycle enzymes and ETC complex activities were found to be low. Lipoic acid administration to aged rats reduced the levels of mitochondrial LPO, 8-oxo-dG and oxidized glutathione and enhanced reduced glutathione, ATP, lipoic acid and ETC complex activities. In young rats lipoic acid administration showed only minimal lowering the levels of LPO, 8-oxo-dG and oxidized glutathione and slight increase in the levels of reduced glutathione, ATP, lipoic acid, TCA cycle enzymes and ETC complex activities. These findings suggest that the dithiol, lipoic acid, provides protection against age-related oxidative damage in the mitochondria of aged rats.

Aging in vertebrates, and the effect of caloric restriction: a mitochondrial free radical production-DNA damage mechanism?

Oxygen is toxic to aerobic animals because it is univalently reduced inside cells to oxygen free radicals. Studies dealing with the relationship between oxidative stress and aging in different vertebrate species and in caloric-restricted rodents are discussed in this review. Healthy tissues mainly produce reactive oxygen species (ROS) at mitochondria. These ROS can damage cellular lipids, proteins and, most importantly, DNA. Although antioxidants help to control this oxidative stress in cells in general, they do not decrease the rate of aging, because their concentrations are lower in long- than in short-lived animals and because increasing antioxidant levels does not increase vertebrate maximum longevity. However, long-lived homeothermic vertebrates consistently have lower rates of mitochondrial ROS production and lower levels of steady-state oxidative damage in their mitochondrial DNA than short-lived ones. Caloric-restricted rodents also show lower levels of these two key parameters than controls fed ad libitum. The decrease in mitochondrial ROS generation of the restricted animals has been recently localized at complex I and the mechanism involved is related to the degree of electronic reduction of the complex I ROS generator. Strikingly, the same site and mechanism have been found when comparing a long- with a short-lived animal species. It is suggested that a low rate of mitochondrial ROS generation extends lifespan both in long-lived and in caloric-restricted animals by determining the rate of oxidative attack and accumulation of somatic mutations in mitochondrial DNA.

Anatomic characterization of human ultra-weak photon emission in practitioners of transcendental meditation(TM) and control subjects

BACKGROUND

Research on human ultra-weak photon emission (UPE, biophoton emission) has raised the question whether a typical human emission anatomic percentage distribution pattern exists in addition to individual subject overall anatomic summation intensity differences. The lowest UPE intensities were observed in two subjects who regularly meditate. Spectral analysis of human UPE has suggested that ultra-weak emission is probably, at least in part, a reflection of free radical reactions in a living system. It has been documented that various physiologic and biochemical shifts follow the long-term practice of meditation and it is inferred that meditation may impact free radical activity.

OBJECTIVE

To systematically quantify, in subjects with long-term transcendental meditation (TM) experience and subjects without this experience, the UPE emission of the anterior torso, head and neck plus the hands in an attempt to document the differences by the two groups.

SUBJECTS

Subjects were 20 men reported to be healthy and nonsmokers. Each of the subjects in the meditation group had practiced TM twice daily for at least the past 10 years.

METHODS

UPE in 20 subjects was recorded in a dark room using a highly sensitive, cooled photomultiplier system designed for manipulation in three directions. The protocol for multisite registration of spontaneous emission includes recording of 12 anatomic locations of anterior torso, head, and hands.

RESULTS

Data demonstrate emission intensities that are lower in TM practitioners as compared to control subjects. The percent contribution of emission from most anatomic locations was not significantly different for TM practitioners and control subjects. Exceptions are the contributions of throat and palm.

CONCLUSION

In subjects with long-term TM experience, the UPE emission is different from control subjects. Data support the hypothesis that free radical reactions can be influenced by TM.

Superoxide dismutase in the prostate lobes of aging Brown Norway rats

BACKGROUND

Spontaneous age-dependent epithelial cell hyperplasia occurs in the lateral and dorsal, but not the ventral, lobes of aging Brown Norway (BN) rats. Diminished antioxidant enzyme activities and increased formation of reactive oxygen species (ROS) promote the pathology of many aging disorders. We investigated the hypothesis that prostatic epithelial cell hyperplasia in the BN rat was related to age-dependent and/or lobe-specific changes in superoxide dismutase (SOD).

MATERIALS AND METHODS

Using Western blots, immunohistochemistry and enzyme activity assays we determined the levels of protein expression, subcellular localization, and activities, respectively, of the three SOD isoforms, cytoplasmic SOD1, mitochondrial SOD2, and extracellular SOD3 in the ventral, lateral, and dorsal prostate lobes of 4-month-old rats with normal prostate morphology, in 24-month-old rats with lobe-specific hyperplasia and in older 30-month-old rats.

RESULTS

We observed little change in SOD activities as a function of age, although expression of SOD3 increased in the prostatic lobes of older rats. SOD2 levels were higher in the lateral lobe of 4- and 24-month-old rats, but declined by 30 months of age to levels in the ventral and dorsal lobes. SOD1 was localized by immunohistochemistry to the nuclei of epithelial cells in all lobes, but the number of immunopositive nuclei increased in the lateral and dorsal lobes of 24-month-old animals. The concentration of zinc was highest in the prostate lobes of 24-month-old animals.

CONCLUSION

Based upon our data, superoxide dismutase is not significantly altered in the rat prostate during aging and thus is unlikely to be an important factor in the evolution of epithelial cell hyperplasia.

Age-dependent DNA repair and cell cycle distribution of human skin fibroblasts in response to UVA irradiation

Ageing process in cells is associated with oxidative stress. Ultraviolet A produces reactive oxygen species responsible for accumulation of DNA and cellular damage. After the evaluation of antioxidant enzyme activities and oxidative stress markers at the basal state, we have studied the responses to UVA stress of coetaneous fibroblasts, isolated from different male donors (2-88 years, n=23) in terms of cytotoxicity, genotoxicity and DNA repair capacities. For this purpose, we have determined level of DNA damage using the comet assay (single strand breaks and alkali-labile sites) and the cell cycle distribution after a 5 J/cm2 irradiation. No differences with age were observed for antioxidant enzyme activities and oxidative stress markers. DNA strand breaks after UVA irradiation (5-20 J/cm2), was found to be age-dependent. DNA repair was slow and also significantly affected by ageing. The cell cycle distribution analysis showed that high repair correlated with high proliferative capacities at basal level. Twenty-four hours after the stress, fraction of young fibroblasts blocked in G1 phase was significantly increased whereas significant modifications concerned the G2-M phase for adult and older fibroblasts. These results indicate an age-dependent decline in the DNA repair capacities correlated with modifications of the cell cycle parameters.

Mitochondrial oxidative stress, aging and caloric restriction: the protein and methionine connection

Caloric restriction (CR) decreases aging rate and mitochondrial ROS (MitROS) production and oxidative stress in rat postmitotic tissues. Low levels of these parameters are also typical traits of long-lived mammals and birds. However, it is not known what dietary components are responsible for these changes during CR. It was recently observed that 40% protein restriction without strong CR also decreases MitROS generation and oxidative stress. This is interesting because protein restriction also increases maximum longevity (although to a lower extent than CR) and is a much more practicable intervention for humans than CR. Moreover, it was recently found that 80% methionine restriction substituting it for l-glutamate in the diet also decreases MitROS generation in rat liver. Thus, methionine restriction seems to be responsible for the decrease in ROS production observed in caloric restriction. This is interesting because it is known that exactly that procedure of methionine restriction also increases maximum longevity. Moreover, recent data show that methionine levels in tissue proteins negatively correlate with maximum longevity in mammals and birds. All these suggest that lowering of methionine levels is involved in the control of mitochondrial oxidative stress and vertebrate longevity by at least two different mechanisms: decreasing the sensitivity of proteins to oxidative damage, and lowering of the rate of ROS generation at mitochondria.

The relationship between plasma levels of oxidized and reduced thiols and early atherosclerosis in healthy adults

OBJECTIVES

The study investigated the relationship between biomarkers of oxidative stress and early atherosclerosis.

BACKGROUND

Oxidative stress is an important etiologic factor in the pathogenesis of vascular disease. We hypothesized that oxidative stress would predict early atherosclerosis in a relatively healthy population.

METHODS

One hundred fourteen healthy non-smokers, without known clinical atherosclerosis, had carotid intima-media thickness (IMT) measured using ultrasound. Oxidative stress was estimated by measuring plasma levels of: 1) glutathione (GSH), an important intracellular antioxidant thiol, its oxidized disulfide form (GSSG), and their redox state (E(h) GSH/GSSG), and 2) cysteine (Cys), an important extracellular antioxidant thiol, its oxidized disulfide form cystine (CySS), and their redox state (E(h)Cys/CySS).

RESULTS

The univariate predictors of IMT were age, body mass index, low-density lipoprotein cholesterol, triglycerides, high-density lipoprotein cholesterol, high-sensitivity C-reactive protein (hs-CRP), and Framingham risk score. Intima-media thickness was also higher in males and hypertensive subjects. Among the oxidative stress markers, GSH (r = -0.39, p < 0.0001), CySS (r = 0.18, p = 0.049), and E(h) GSH/GSSG (r = 0.34, p < 0.0002) correlated with IMT. After adjusting for traditional risk factors and hs-CRP, only E(h) GSH/GSSG remained an independent predictor of IMT. E(h) GSH/GSSG predicted IMT in a manner that was both independent of and additive to Framingham risk score.

CONCLUSIONS

Glutathione redox state (E(h) GSH/GSSG), an in vivo measure of intracellular oxidative stress, is an independent predictor for the presence of early atherosclerosis in an otherwise healthy population. This finding supports a role for oxidative stress in the pathogenesis of premature atherosclerosis, and its measurement may help in the early identification of asymptomatic subjects at risk of atherosclerotic disease.

Modulation of cutaneous wound healing by ozone: Differences between young and aged mice

Cutaneous tissues are frequently exposed to prooxidative environments, including UV radiation and air pollutants. Among the latter, ozone (O(3)) is of particular concern because of its high and dominating presence in photochemical smog. It is well known that O(3) depletes small molecular weight antioxidants, oxidizes proteins, induces lipid peroxidation and activates cellular responses in various tissues. Using an in vivo model (SKH-1 hairless mice), the interaction between O(3) exposure (0.5ppmx6h/day) and age was examined in relation to cutaneous wound healing. Compared to younger (8 weeks) mice, older (18 months) mice exposed to O(3) (day 0 to day 9 after wounding) exhibited delayed wound closure, increased lipid peroxidation (measured as 4-HNE protein adducts) and protein oxidation (measured as carbonyls concentration) and decreased levels of P-IkappaBalpha and TGFbeta protein. These findings support the hypothesis that oxidant pollutant exposure and age interact so as to disrupt normal wound healing processes.

Defective cholesterol efflux in Werner syndrome fibroblasts and its phenotypic correction by Cdc42, a RhoGTPase

Werner syndrome (WS) is characterized by the early onset of senescent phenotypes including premature atherosclerotic cardiovascular diseases, although the underlying molecular mechanism for atherosclerosis has not been fully understood yet. Cholesterol efflux from the cells is the initial step of reverse cholesterol transport, a major protective system against atherosclerosis. The aim of the present study was to determine whether this crucial step may be altered in WS. We examined intracellular lipid transport and cholesterol efflux and the expression levels of its related molecules in skin fibroblasts obtained from patients with WS. Cholesterol efflux was markedly reduced in the WS fibroblasts in association with increased cellular cholesterol. Fluorescent recovery after photobleaching (FRAP) technique revealed that intracellular lipid transport around Golgi apparatus was markedly reduced when using a C6-NBD-Ceramide as a tracer. Cdc42 protein and its GTP-bound form were markedly reduced in the WS fibroblasts. The complementation of wild-type Cdc42 corrected cholesterol efflux, intracellular lipid transport, and cellular cholesterol levels in the WS fibroblasts. These data indicated that the reduced expression of Cdc42 may be responsible for the abnormal lipid transport, which in turn might be related to the cardiovascular manifestations in WS.

Effects of Age and Diet on Rat Skin Histology

OBJECTIVE/HYPOTHESIS

To document age-related histologic morphometric changes of rat skin and the effects of calorie restriction on such changes.

STUDY DESIGN

Fischer 344 rats of three age groups (young, 4 mo; adult, 1 year; old, 24+ months) were procured from ad libitum (AL) diet and calorie-restricted (CR) colonies of the National Institute of Aging and were used for histologic study. Each study group consisted of six animals.

METHODS

Skin samples from the dorsum (DS) and footpad (FP) of these animals were excised and processed for histology with staining techniques for general morphology (hematoxylin-eosin-phloxine) and for differentiation of collagen bundles and elastic fibers (Verhoeff-van Gieson technique). Light microscopic morphometric and stereologic point counting procedures were applied manually to tissue sections to obtain quantitative data on the depth of the epidermis, dermis, and stratum corneum, epidermal nuclear number, and percentage fraction of collagen, elastic fibers, capillaries, and pilosebaceous units. Data were analyzed with two-way of analysis of variance (ANOVA) to determine significant effects of age, diet, and age-diet interaction on these parameters in AL rats and their age-matched cohorts.

RESULTS

Significant effects of age, diet, or age-diet interaction were observed in respect of the thickness of epidermis, dermis, stratum corneum of FP, epidermal nuclear number, collagen percentage fraction, and area fraction of capillaries. DS epidermis showed increasing thickness in AL group, but this was reduced in CR rats. A similar trend in DS dermal depth was observed. Fewer capillaries were present in aging CR rats. The DS epidermal nuclear profiles and collagen area fraction also showed effects of diet and age-diet interaction. Aging changes, especially the effect of CR, was more evident in the measured parameters of dorsal skin. No alterations were observed in the distribution of pilosebaceous units and elastic fiber profiles of the skin.

CONCLUSIONS

The Fischer 344 rat shows many age-related changes in the skin, some of which are different from data reported in literature. The pattern of aging changes in skin parameters was different in the two groups, suggesting an in influence of CR. CR appears to modify the aging rate of some skin components, and this may be caused by metabolic changes imposed by diet.

DietaryGarcinia cambogia does not modify skin properties of mice with or without excessive sucrose intake

The influence of 3.3% Garcinia cambogia extract on the properties of mouse skin with or without 10% sucrose water loading was investigated. Mice (7-week-old) were given free access to a control diet or a diet containing Garcinia cambogia extract. They were also given water alone or both water and sucrose water. Their skin was compared by both biochemical and histological methods. The collagen and triacylglycerol contents were not significantly different among the four groups. Similarly, electron microscopy revealed no differences in the thickness of the dermis layer or the subcutaneous tissue layer. Mice given the diet containing Garcinia cambogia tended to have a reduced total number of adipocytes, but not significantly. These results suggest that Garcinia cambogia supplementation for at least 4 weeks does not induce a negative effect on skin properties in mice irrespective of excessive sucrose intake.

Functional Hyperemia is Reduced in Skeletal Muscle of Aged Rats

OBJECTIVE

To test the hypothesis that active hyperemia is reduced in skeletal muscle of old rats due to a decreased bioavailability of prostanoids, which in turn is due to increased oxidative stress.

METHODS

The microvasculature of the spinotrapezius muscle of 3-, 12-, and 24-month male Sprague-Dawley rats was examined using in vivo videomicroscopy. Arteriolar diameter and centerline red cell velocity were measured in resting and contracting muscle. The effect of prostanoids was examined using indomethacin (10 microM), and passive resting arteriolar diameters were determined using adenosine (100 microM). Lipid peroxidation was assessed ex vivo by measuring tissue levels of malondialdehyde.

RESULTS

Arteriolar diameters and blood flow in resting muscle did not differ among the age groups, but increases in diameter and flow during muscle contraction in young rats were greater than in the two older age groups. Indomethacin did not affect resting arteriolar diameters and blood flow in 3- and 12-month rats, but significantly decreased both parameters in 24-month rats. Indomethacin had no effect on arteriolar diameter and blood flow responses during muscle contraction in any age group. Passive resting diameters of arterioles were significantly smaller in 12- and 24-month rats than in 3-month rats. Tissue levels of TBARS were not different among the three age groups.

CONCLUSIONS

Arteriolar tone and blood flow in resting skeletal muscle of rats is not altered with age, whereas the increases in these variables that normally accompany muscle contraction are markedly impaired during aging. Neither cyclooxygenase metabolites nor lipid peroxidation appear to be involved in this impairment.

Cytoprotective effect on oxidative stress and inhibitory effect on cellular aging of Terminalia chebula fruit

The ethanol extract from the fruit of Terminalia chebula (Combretaceae) exhibited significant inhibitory activity on oxidative stress and the age-dependent shortening of the telomeric DNA length. In the peroxidation model using t-BuOOH, the T. chebula extract showed a notable cytoprotective effect on the HEK-N/F cells with 60.5 +/- 3.8% at a concentration of 50 microg/ml. In addition, the T. chebula extract exhibited a significant cytoprotective effect against UVB-induced oxidative damage. The life-span of the HEK-N/F cells was elongated by 40% as a result of the continuous administration of 3 microg/ml of the T. chebula extract compared to that of the control. These observations were attributed to the inhibitory effect of the T. chebula extract on the age-dependent shortening of the telomere, length as shown by the Southern blots of the terminal restriction fragments (TRFs) of DNA extracted from subculture passages.

Cytoprotective effect on oxidative stress and inhibitory effect on cellular aging of Uncaria sinensis Havil

The ethanol extract from the hooks and stems of Uncaria sinensis Havil (Rubiaceae) exhibited significant inhibitory activity on oxidative stress and the age-dependent shortening of the telomeric DNA length. In the peroxidation model using t-BuOOH, the Uncaria sinensis extract showed a notable cytoprotective effect on the HEK-N/F cells with 65.0 +/- 3.0% of cell viability when compared with control cells at a concentration of 50 microg/ml. In addition, the Uncaria sinensis extract exhibited a significant cytoprotective effect against UVB-induced oxidative damage. The life-span of the HEK-N/F cells was elongated by 201% as a result of the continuous administration of 3 microg/ml of the Uncaria sinensis extract compared to that of the control. These observations were attributed to the inhibitory effect of the Uncaria sinensis extract on the age-dependent shortening of the telomere length as shown by the Southern blots of the terminal restriction fragments (TRFs) of DNA extracted from subculture passages.

Comparison of oxidative stress biomarker profiles between acute and chronic wound environments

Increasing evidence implicates excessive reactive oxygen species (ROS) generation and ROS-derived degradation products in the pathogenesis of many skin diseases. While numerous attempts have been made to identify prognostic biomarkers of wound healing in skin, these have met with limited success. This study examined the profiles of various oxidative stress biomarkers, namely total protein carbonyl content (from protein oxidation), malondialdehyde content (from lipid peroxidation), and the total antioxidant capacities, in acute wound fluid (n= 10) and chronic wound fluid (n= 12), using a rapid, noninvasive collection technique. Protein carbonyl content was quantified spectrophotometrically and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis/Western blotting, following 2,4-dinitrophenylhydrazine derivitization. Malondialdehyde levels were similarly quantified, following N-methyl-2-phenylindole derivitization. Total antioxidant capacity was determined via wound fluid inhibition of cytochrome C reduction by a superoxide radical flux. Acute wound fluid contained higher protein carbonyl content than chronic wound fluid, particularly evident following sodium dodecyl sulfate-polyacrylamide gel electrophoresis/Western blot analysis under nonreducing and reducing conditions (p < 0.001 and p < 0.02, respectively), related to significantly higher protein levels (p = 0.0005) in acute wound fluid. Human serum albumin ( approximately 66 kDa) was identified as the most prominent protein oxidized in both acute and chronic wound fluid, which may contribute to the reduced albumin and total protein levels in chronic wound fluid. No significant difference (p > 0.1) in malondialdehyde levels or total antioxidant capacities were determined between acute and chronic wound fluids, although chronic wound fluid exhibited significantly higher total antioxidant capacities (p < 0.005), accounting for variations in wound fluid protein content. These findings suggest an adaptation in the antioxidant profiles of chronic wound fluid to counteract the loss of consumed antioxidants in the chronic wound environment. This study highlights the roles of ROS/antioxidants in skin wound healing, their possible involvement in chronic wounds and the potential value of ROS-induced biomarkers in wound healing prognosis.

Oxidative stress: a theoretical model or a biological reality?

Although oxidative stress has been extensively studied the last fifteen years, many physicians and biologists are still sceptical concerning its interest in biology and medicine. This is probably due, in part, to the fact that this subject is a matter of biophysics, and the first studies reported were written using a physical language that inspired these people used to a more concrete problematic very little. Another problem is the difficulty to detect the species mediating oxidative stress, and to determine their role in biological processes. This review is aimed at presenting oxidative stress, as well as reactive oxygen species and free radicals--the molecules that mediate it--in a clear form able to convince all researchers involved in life sciences that these short-lived intermediates are indissociable from any aerobic organism. Moreover, if reactive oxygen species and free radicals are undoubtedly involved in many pathologies, they have physiological functions too.

Dietary CLA and DHA modify skin properties in mice

This study investigated the influence of PUFA on the properties of mouse skin. Mice (3 wk old) were given free access to oils high in linoleic acid, CLA, or DHA for 4 wk. At the end of the experiment, their skins were compared by both biochemical and histological methods. No significant differences in lipid and collagen contents were detected among treatments, although the FA composition in the skin was altered depending upon the FA composition of the supplemented oils. Electron microscopy revealed that the subcutaneous tissue layers in the CLA and DHA groups were significantly thinner than that in the high linoleic acid group, whereas no differences in the thickness of dermis layers were observed among the three groups. These results suggest that skin properties in mice are readily modified by dietary FA sources within 4 wk of dietary oil supplementation.

Antioxidant enzyme activity in human stratum corneum shows seasonal variation with an age-dependent recovery

The stratum corneum, as the body's principal barrier to the environment, is continuously exposed to environmental sources of reactive oxygen species like ultraviolet light, ozone, and pollution. Reactive oxygen species are believed to be involved in cancer, aging, and inflammatory skin disorders. We have developed a method to measure catalase and superoxide dismutase activity on tape strippings from the human stratum corneum and demonstrated a gradient of antioxidant enzyme activity across the stratum corneum with decreasing levels towards the skin surface. Sun exposure resulted in a seasonal variation of the catalase activity in stratum corneum, with low activities in summer and higher activities in winter for the same person, whereas superoxide dismutase activity in stratum corneum did not seem to vary in those conditions. Exposure of human skin to broadband ultraviolet-A resulted in a dose-dependent deactivation of the catalase activity in stratum corneum within 24 h, whereas exposure to ultraviolet-B had no effect. Superoxide dismutase activity in stratum corneum was not affected by ultraviolet-A or ultraviolet-B irradiation within 24 h. After exposure to a dose of 15 J per cm2 broadband ultraviolet-A, full recovery of the catalase activity occurred in 3-4 wk at an age-dependent rate. We conclude that sun exposure results in a disturbed catalase to superoxide dismutase ratio in the stratum corneum. This may lead to an increased vulnerability to oxidative damage in stratum corneum barrier components. These results therefore stress the importance of providing efficient protection for this internal defense mechanism in sun-exposed areas of the skin.

Redox analysis of human plasma allows separation of pro-oxidant events of aging from decline in antioxidant defenses

Oxidative stress is a component of diseases and degenerative processes associated with aging. However, no means are available to assess causative oxidative events separately from decline in function of protective antioxidant systems. Previous studies show that ongoing oxidative processes maintain plasma cysteine/cystine redox at a value that is more oxidized than the antioxidant glutathione/glutathione disulfide (GSH/GSSG) system, suggesting that redox analysis of these plasma thiols could allow separate evaluation of an increase in oxidative events from a decline in antioxidant function. The present study uses measurement of cysteine/cystine and GSH/GSSG redox in plasma of 122 healthy individuals aged 19-85 years to determine whether thiol-disulfide redox changes occur with age. The results show a linear oxidation of cysteine/cystine redox state with age at a rate of 0.16 mV/year over the entire age span. In contrast, GSH/GSSG redox was not oxidized prior to 45 years and subsequently was oxidized at a nearly linear rate of 0.7 mV/year. These data suggest that there is a continuous, linear increase in oxidative events throughout adult life but that the capacity of the GSH antioxidant system is maintained until 45 years and then declines rapidly. The data further suggest that redox states of cysteine/cystine and GSH/GSSG provide an approach to clinically distinguish between increased causative oxidative events and decreased GSH antioxidant function. In principle, such analyses can be used to assess efficacy of intervention strategies against oxidative stress prior to or early after onset of clinical symptoms in aging and age-related disease.

Parameters related to oxygen free radicals in erythrocytes, plasma and epidermis of the hairless rat

The following parameters related to oxygen free radicals (OFR) were determined in erythrocytes and the epidermis of hairless rats: catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), reduced (GSH) and oxidized (GSSG) glutathione, glutathione S-transferase (GST), superoxide dismutase (SOD) and thiobarbituric acid reactive substances (TBARS). GSH, GSSG and TBARS were also analyzed in plasma. In erythrocytes, the Pearson correlation coefficients (r) were significant (p < 0.001) between glutathione and other parameters as follows: GSH correlated negatively with GSSG (r = -0.665) and TBARS (r = -0.669); GSSG correlated positively with SOD (r = 0.709) and TBARS (r = 0.752). Plasma GSSG correlated negatively with erythrocytic thermostable GST activity (r = -0.608; p=0.001) and with erythrocytic total GST activity (r = -0.677; p < 0.001). In epidermis (p < 0.001 in all cases), GSH content correlated with GSSG (r = 0.682) and with GPx (r = 0.663); GSSG correlated with GPx (r = 0.731) and with GR (r = 0.794). By multiple linear regression analysis some predictor variables (R(2)) were found: in erythrocytes, thermostable GST was predicted by total GST activity and GSSG, GSSG content was predicted by GSH and by the GSH/GSSG ratio and GPx activity was predicted by GST, CAT and SOD activities; in epidermis, GSSG was predicted by GR and SOD activities and GR was predicted by GSSG, TBARS and GPx. It is concluded that the hairless rat is a good model for studying OFR-related parameters simultaneously in blood and skin, and that it may provide valuable information about other animals under oxidative stress.

Endogenous oxidative stress: relationship to aging, longevity and caloric restriction

Available studies are consistent with the possibility that oxygen radicals endogenously produced by mitochondria are causally involved in the determination of the rate of aging in homeothermic vertebrates. Oxidative damage to tissue macromolecules seems to increase during aging. The rate of mitochondrial oxygen radical generation of post-mitotic tissues is negatively correlated with animal longevity. In agreement with this, long-lived animals show lower levels of oxidative damage in their mitochondrial DNA (mtDNA) than short-lived ones, whereas this does not occur in nuclear DNA (nDNA). Caloric restriction, which decreases the rate of aging, also decreases mitochondrial oxygen radical generation and oxidative damage to mitochondrial DNA. This decrease in free radical generation occurs in complex I and is due to a decrease in the degree of electronic reduction of the complex I free radical generator, similarly to what has been described in various cases in long-lived animals. These results suggest that similar mechanisms have been used to extend longevity through decreases in oxidative stress in caloric restriction and during the evolution of species with different longevities.

Detection of oxidative species and low-molecular-weight DNA in skin following dermal exposure with JP-8 jet fuel

Dermal absorption of JP-8 jet fuel can lead to skin irritation within hours after exposure. This study detected the formation of oxidative species and low-molecular-weight DNA in rat skin as potential indicators of JP-8-induced skin injury. At 0, 1, 2, 4 and 6 h after the beginning of a 1-h exposure, skin samples were removed and analyzed for oxidative species formation and low-molecular-weight DNA analysis. At 1, 2 and 4 h, mean oxidative species levels increased significantly (P < 0.05) above unexposed samples. Significantly higher (P < 0.05) low-molecular-weight DNA values were observed at 4 and 6 h compared with unexposed controls. These results demonstrate significant increases in oxidative species and low-molecular-weight DNA levels in the skin following dermal exposure to JP-8. These responses may serve as indicators of skin injury following exposure to JP-8 jet fuel and other volatile chemicals or mixtures.