Age-related change of phosphatidylcholine hydroperoxide and phosphatidylethanolamine hydroperoxide levels in normal human red blood cells

Marine Plasmalogens: A Gift from the Sea with Benefits for Age-Associated Diseases

Aging increases oxidative and inflammatory stress caused by a reduction in metabolism and clearance, thus leading to the development of age-associated diseases. The quality of our daily diet and exercise is important for the prevention of these diseases. Marine resources contain various valuable nutrients, and unique glycerophospholipid plasmalogens are found abundantly in some marine invertebrates, including ascidians. One of the major classes, the ethanolamine class (PlsEtn), exists in a high ratio to phospholipids in the brain and blood, while decreased levels have been reported in patients with age-associated diseases, including Alzheimer's disease. Animal studies have shown that the administration of marine PlsEtn prepared from marine invertebrates improved PlsEtn levels in the body and alleviated inflammation. Animal and human studies have reported that marine PlsEtn ameliorates cognitive impairment. In this review, we highlight the biological significance, relationships with age-associated diseases, food functions, and healthcare materials of plasmalogens based on recent knowledge and discuss the contribution of marine plasmalogens to health maintenance in aging.

Oxidative Stress Is a Concept, Not an Indication for Selective Antioxidant Treatment

The steady-state redox status is physiologically important and therefore homeostatically maintained. Changes in the status result in signaling (eustress) or oxidative damage (distress). Oxidative stress (OS) is a hard-to-quantitate term that can be estimated only based on different biomarkers. Clinical application of OS, particularly for selective antioxidant treatment of people under oxidative stress, requires quantitative evaluation and is limited by the lack of universal biomarkers to describe it. Furthermore, different antioxidants have different effects on the redox state. Hence, as long as we do not have the possibility to determine and quantify OS, therapeutic interventions by the "identify-and-treat" approach cannot be assessed and are, therefore, not likely to be the basis for selective preventive measures against oxidative damage.

Common and Novel Markers for Measuring Inflammation and Oxidative Stress Ex Vivo in Research and Clinical Practice-Which to Use Regarding Disease Outcomes?

Many chronic conditions such as cancer, chronic obstructive pulmonary disease, type-2 diabetes, obesity, peripheral/coronary artery disease and auto-immune diseases are associated with low-grade inflammation. Closely related to inflammation is oxidative stress (OS), which can be either causal or secondary to inflammation. While a low level of OS is physiological, chronically increased OS is deleterious. Therefore, valid biomarkers of these signalling pathways may enable detection and following progression of OS/inflammation as well as to evaluate treatment efficacy. Such biomarkers should be stable and obtainable through non-invasive methods and their determination should be affordable and easy. The most frequently used inflammatory markers include acute-phase proteins, essentially CRP, serum amyloid A, fibrinogen and procalcitonin, and cytokines, predominantly TNFα, interleukins 1β, 6, 8, 10 and 12 and their receptors and IFNγ. Some cytokines appear to be disease-specific. Conversely, OS-being ubiquitous-and its biomarkers appear less disease or tissue-specific. These include lipid peroxidation products, e.g., F2-isoprostanes and malondialdehyde, DNA breakdown products (e.g., 8-OH-dG), protein adducts (e.g., carbonylated proteins), or antioxidant status. More novel markers include also -omics related ones, as well as non-invasive, questionnaire-based measures, such as the dietary inflammatory-index (DII), but their link to biological responses may be variable. Nevertheless, many of these markers have been clearly related to a number of diseases. However, their use in clinical practice is often limited, due to lacking analytical or clinical validation, or technical challenges. In this review, we strive to highlight frequently employed and useful markers of inflammation-related OS, including novel promising markers.

Lipid hydroperoxides in nutrition, health, and diseases

Research on lipid peroxidation in food degradation, oil and fat nutrition, and age-related diseases has gained significant international attention for the view of improvement of societal health and longevity. In order to promote basic studies on these topics, a chemiluminescence detection-high performance liquid chromatography instrument using a high-sensitivity single photon counter as a detector was developed. This instrument enabled us to selectively detect and quantify lipid hydroperoxides, a primary product of lipid peroxidation reactions, as hydroperoxide groups at the lipid class level. Furthermore, an analytical method using liquid chromatography-tandem mass spectrometry has been established to discriminate the position and stereoisomerization of hydroperoxide groups in lipid hydroperoxides. Using these two methods, the reaction mechanisms of lipid peroxidation in food and in the body have been confirmed.

Impact of ApoE Polymorphism and Physical Activity on Plasma Antioxidant Capability and Erythrocyte Membranes

The allele epsilon 4 (ε4) of apolipoprotein E (ApoE) is the strongest genetic risk factor for Alzheimer's disease (AD). ApoE protein plays a pivotal role in the synthesis and metabolism of amyloid beta (Aβ), the major component of the extracellular plaques that constitute AD pathological hallmarks. Regular exercise is an important preventive/therapeutic tool in aging and AD. Nevertheless, the impact of physical exercise on the well-being of erythrocytes, a good model of oxidative stress and neurodegenerative processes, remains to be investigated, particularly depending on ApoE polymorphism. Herein, we evaluate the oxidative status, Aβ levels, and the membrane's composition of erythrocytes in a cohort of human subjects. In our hands, the plasma antioxidant capability (AOC), erythrocytes membrane fluidity, and the amount of phosphatidylcholine (PC) were demonstrated to be significantly decreased in the ApoE ε4 genotype and non-active subjects. In contrast, erythrocyte Aβ content and lipid peroxidation increased in ε4 carriers. Regular physical exercise was associated with an increased plasma AOC and membrane fluidity, as well as to a reduced amount of erythrocytes Aβ. Altogether, these data highlight the influence of the ApoE genotype on erythrocytes' well-being and confirm the positive impact of regular physical exercise.

Oxidative Phospholipidomics in health and disease: Achievements, challenges and hopes

Phospholipid peroxidation products are recognized as important bioactive lipid mediators playing an active role as modulators in signalling events in inflammation, immunity and infection. The biochemical responses are determined by the oxidation structural features present in oxPL modulating biophysical and biological properties in model membranes and lipoproteins. In spite of the extensive work conducted with model systems over the last 20 years, the study of oxPL in biological systems has virtually stagnated. In fact, very little is known concerning the predominant oxPL in fluids and tissues, their basal levels, and any variations introduced with age, gender and ethnicity in health and disease. In consequence, knowledge on oxPL has not yet translated into clinical diagnostic, in the early and timely diagnosis of "silent" diseases such as atherosclerosis and cardiovascular diseases, or as prognosis tools in disease stratification and particularly useful in the context of multimorbidities. Their use as therapeutic solutions or the development of innovative functional biomaterials remains to be explored. This review summarizes the achievements made in the identification of oxPL revealing an enormous structural diversity. A brief overview of the challenges associated with the analysis of such diverse array of products is given and a critical evaluation on key aspects in the analysis pipeline that need to be addressed. Once these issues are addressed, Oxidative Phospholipidomics will hopefully lead to major breakthrough discoveries in biochemistry, pharmaceutical, and clinical areas for the upcoming 20 years. This article is part of Special Issue entitled 4-Hydroxynonenal and Related Lipid Oxidation Products.

Myoglobinemia markers with potential applications in forensic sample analysis: lipid markers in myoglobinemia for postmortem blood

The crush syndrome, in which rhabdomyolysis and trauma occur as a result of heat stroke and drug intoxication, can lead to myoglobinemia. This condition can be diagnosed by measuring myoglobin (Mb) levels in blood and urine. However, postmortem Mb levels are unreliable indicators, since blood Mb concentration drastically increases within a very short time after death and urine cannot always be obtained at dissection; this makes it difficult to diagnose myoglobinemia in a corpse. To address this issue, in this study, we used a lipidomics approach to identify markers that can be used to detect myoglobinemia in postmortem blood samples. We found that increases in levels of fatty acid oxides such as stearic, oleic, linoleic, and arachidonic acid and decreases in levels of plasmalogens and phosphatidylethanolamine in the blood were associated with high Mb level. These results demonstrate that postmortem samples are amenable to lipidomics analysis and provide a set of markers other than Mb that can be used for postmortem diagnosis of myoglobinemia.

Luminol-based chemiluminescent signals: clinical and non-clinical application and future uses

Chemiluminescence (CL) is an important method for quantification and analysis of various macromolecules. A wide range of CL agents such as luminol, hydrogen peroxide, fluorescein, dioxetanes and derivatives of oxalate, and acridinium dyes are used according to their biological specificity and utility. This review describes the application of luminol chemiluminescence (LCL) in forensic, biomedical, and clinical sciences. LCL is a very useful detection method due to its selectivity, simplicity, low cost, and high sensitivity. LCL has a dynamic range of applications, including quantification and detection of macro and micromolecules such as proteins, carbohydrates, DNA, and RNA. Luminol-based methods are used in environmental monitoring as biosensors, in the pharmaceutical industry for cellular localization and as biological tracers, and in reporter gene-based assays and several other immunoassays. Here, we also provide information about different compounds that may enhance or inhibit the LCL along with the effect of pH and concentration on LCL. This review covers most of the significant information related to the applications of luminol in different fields.

Ingestion of Chlorella reduced the oxidation of erythrocyte membrane lipids in senior Japanese subjects

Accumulation of phospholipid hydroperoxide (PLOOH) in erythrocyte membranes is an abnormality found in patients with senile dementia, including those with Alzheimer's disease. In our previous studies, dietary xanthophylls (polar carotenoids such as lutein) were hypothesized to inhibit lipid peroxidation. In the present study, we conducted a randomized, double-blind, placebo-controlled human trial to assess the impact for a total of 2 months Chlorella supplementation (8 g Chlorella/day/person; equivalent to 22.9 mg lutein/day/person) on PLOOH and carotenoid concentrations in erythrocytes as well as plasma of 12 normal senior subjects. After 1 or 2 months of treatment, erythrocytes and plasma lutein concentrations increased in the Chlorella group but not in the placebo group. In the Chlorella-supplemented group, erythrocyte PLOOH concentrations after a total of 2 months of treatment were lower than the concentrations before supplementation. These results suggest that Chlorella ingestion improved erythrocyte antioxidant status and lowered PLOOH concentrations. These reductions might contribute to maintaining the normal function of erythrocytes and prevent the development of senile dementia.

Multi-element distribution profile in Sprague-Dawley rats: effects of intratracheal instillation of Cr(VI) and Zn intervention

Our previous epidemiological study revealed that co-exposure of [Cr(VI)] with small amount of heavy metals could induce peripheral blood element imbalance, but little was known about the contribution of Cr(VI) itself and the multi-element distribution profile in other target tissues. We explored element homeostasis in the blood, RBC, serum and lung after Cr(VI) exposure and Zn intervention. 60 Sprague-Dawley male rats received intratracheal instillation of Cr(VI) (0, 0.063, 0.630mgCr/kg) weekly and/or intragastric administration of zinc sulfate (0, 10mgZn/kg) daily for one month. Element contents and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations were determined. Dose-response relationship was observed among rats exposed to Cr(VI). Ca, Mg, Mn in the blood, Fe, Mg, Se in the serum, and Mg and Zn in lung tissue decreased significantly, while Ca, Co, Cr, Mg, Mn, Se in RBC, and Ca, Co, Mo in the lung increased after Cr(VI) exposure. The alteration trends manifested differently, with RBC the most sensitive. Cr induced increase of urinary 8-OHdG, which decreased after Zn intervention. Zn intervention could help to restore element homeostasis after Cr(VI) exposure, especially for Ca, Fe, Mg and Se.

The comparison of the effects of sevoflurane inhalation anesthesia and intravenous propofol anesthesia on oxidative stress in one lung ventilation

BACKGROUND

The aim of this study is to compare the effects of sevoflurane and propofol on one lung ventilation (OLV) induced ischemia-reperfusion injury (IRI) by determining the blood gas, ischemia-modified albumin (IMA), and malonyldialdehyde (MDA).

MATERIAL AND METHODS

Forty-four patients undergoing thoracic surgery with OLV were randomized in two groups (sevoflurane Group S, propofol Group P). Anesthesia was inducted with thiopental and was maintained with 1-2.5% of sevoflurane within the 40/60% of O2/N2O mixture in Group S. In Group P anesthesia was inducted with propofol and was maintained with infusion of propofol and remifentanil. Hemodynamic records and blood samples were obtained before anesthesia induction (t 1), 1 min before two lung ventilation (t 2), 30 min after two lung ventilation (t 3), and postoperative sixth hours (t 4).

RESULTS

Heart rate at t 2 and t 3 in Group P was significantly lower than that in Group S. While there were no significant differences in terms of pH and pCO2, pO2 at t 2 and t 3 in Group S was significantly lower than that in Group P. IMA levels at t 4 in Group S were significantly lower than those in Group P.

CONCLUSION

Sevoflurane may offer protection against IRI after OLV in thoracic surgery.

Ischemia-reperfusion injury and volatile anesthetics

Ischemia-reperfusion injury (IRI) is induced as a result of reentry of the blood and oxygen to ischemic tissue. Antioxidant and some other drugs have protective effect on IRI. In many surgeries and clinical conditions IRI is counteract inevitable. Some anesthetic agents may have a protective role in this procedure. It is known that inhalational anesthetics possess protective effects against IRI. In this review the mechanism of preventive effects of volatile anesthetics and different ischemia-reperfusion models are discussed.

Hemoglobin redox reactions and red blood cell aging

SIGNIFICANCE

The physiological mechanism(s) for recognition and removal of red blood cells (RBCs) from circulation after 120 days of its lifespan is not fully understood. Many of the processes thought to be associated with the removal of RBCs involve oxidative stress. We have focused on hemoglobin (Hb) redox reactions, which is the major source of RBC oxidative stress.

RECENT ADVANCES

The importance of Hb redox reactions have been shown to originate in large parts from the continuous slow autoxidation of Hb producing superoxide and its dramatic increase under hypoxic conditions. In addition, oxidative stress has been shown to be associated with redox reactions that originate from Hb reactions with nitrite and nitric oxide (NO) and the resultant formation of highly toxic peroxynitrite when NO reacts with superoxide released during Hb autoxidation.

CRITICAL ISSUES

The interaction of Hb, particularly under hypoxic conditions with band 3 of the RBC membrane is critical for the generating the RBC membrane changes that trigger the removal of cells from circulation. These changes include exposure of antigenic sites, increased calcium leakage into the RBC, and the resultant leakage of potassium out of the RBC causing cell shrinkage and impaired deformability.

FUTURE DIRECTIONS

The need to understand the oxidative damage to specific membrane proteins that result from redox reactions occurring when Hb is bound to the membrane. Proteomic studies that can pinpoint the specific proteins damaged under different conditions will help elucidate the cellular aging processes that result in cells being removed from circulation.

Microtubule formation and activities of antioxidative enzymes in PC12 cells exposed to phosphatidylcholine hydroperoxides

Aging increases free radical generation and lipid oxidation and, thereby, mediates neurodegenerative diseases. As the brain is rich in lipids (polyunsaturated fatty acids), the antioxidative system plays an important role in protecting brain tissues from oxidative injury. The changes in microtubule formation and antioxidative enzyme activities have been investigated in rat pheochromocytoma PC12 cells exposed to various concentrations of phosphatidylcholine hydroperoxides (PCOOH). We measured three typical antioxidative enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). The microtubule assembly system was dependent on the antioxidative enzyme system in cells exposed to oxidative stress. The activities of the three enzymes increased in a PCOOH exposure-dependent manner. In particular, the changes in the activity as a result of PCOOH exposure were similar in the three antioxidative enzymes. This is the first report indicating the compatibility between the tubulin-microtubule and antioxidative enzyme systems in cells that deteriorate as a result of phospholipid hydroperoxide administration from an exterior source. The descending order of sensitivity of the three enzymes to PCOOH is also discussed.

Amyloid β-induced erythrocytic damage and its attenuation by carotenoids

The presence of amyloid β-peptide (Aβ) in human blood has recently been established, and it has been hypothesized that Aβ readily contacts red blood cells (RBC) and oxidatively impairs RBC functions. In this study, we conducted in vitro and in vivo studies, which provide evidence that Aβ induces oxidative injury to RBC by binding to them, causing RBC phospholipid peroxidation and diminishing RBC endogenous carotenoids, especially xanthophylls. This type of damage is likely to injure the vasculature, potentially reducing oxygen delivery to the brain and facilitating Alzheimer's disease (AD). As a preventive strategy, because the Aβ-induced RBC damage could be attenuated by treatment of RBC with xanthophylls, we suggest that xanthophylls may contribute to the prevention of AD.

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.

Studies with myoglobin variants indicate that released hemin is the primary promoter of lipid oxidation in washed fish muscle

Variants of sperm whale myoglobin (Mb) were used to assess the mechanism of heme protein-mediated lipid oxidation in washed cod muscle. A myoglobin variant with high hemin affinity (V68T) was an exceptionally poor promoter of lipid oxidation, while a Mb variant with low hemin affinity (H97A) was a potent promoter of lipid oxidation. V68T releases hemin slowly due to the ability of threonine to hydrogen bond with coordinated water and the distal histidine within the heme crevice. H97A rapidly releases hemin because the relatively small alanine residue creates a channel for water to easily enter the heme crevice which weakens the covalent linkage of hemin to the proximal histidine. A variant sensitive to heme degradation (L29F/H64Q) was a weaker promoter of lipid oxidation compared to wild-type Mb. This suggests that degrading the heme ring and releasing iron decreased the ability of Mb to promote lipid oxidation. Free radicals resulting from hemin-mediated decomposition of lipid hydroperoxides have the capacity to propagate lipid oxidation and degrade hemin catalyst. This may explain why heme proteins behave as reactants rather than "catalysts" of lipid oxidation in washed cod. Collectively these studies strongly suggest that released hemin is the critical entity that drives heme protein-mediated lipid oxidation in washed fish muscle.

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.

Phosphatidylcholine hydroperoxide levels in human plasma are lower than previously reported

The quantification of PC hydroperoxide (PCOOH) in human plasma was studied by HPLC with chemiluminescence detection (HPLC-CL). We identified for the first time the monohydroperoxide of 1-palmitoyl-2-linoleoyl-PC hydroperoxide (PC 16:0/18:2-OOH) in plasma by LC-MS and HPLC-CL. The standard compound, PC 16:0/18:2-OOH (synthetic PCOOH), as well as PCOOH from egg yolk, was used. Comparison of the PCOOH concentration in each participant's plasma as determined by use of a Finepak SIL NH2 column with 2-propanol/methanol/water as the mobile phase (system A, the conventional method) gave a higher concentration than did an LC-18-DB column with methanol containing 0.01% triethylamine (system B). The mean PCOOH concentration for the 43 healthy volunteers was 55.1+/-30.4 pmol/mL (mean+/-SD) for system A and 16.3+/-9.9 pmol/mL for system B. Moreover, the main peak of the plasma extract appeared at a different time from that of synthetic PCOOH or egg yolk PCOOH in system A, whereas in system B plasma sample retention time practically corresponded to that of standard PCOOH. These findings confirm that the PCOOH plasma concentration is not so high as previously reported.

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.

Increase of serum phosphatidylcholine hydroperoxide dependent on glycemic control in type 2 diabetic patients

In order to clarify the relationship between serum phosphatidylcholine hydroperoxide (PCOOH) levels and blood glucose control in type 2 diabetes patients (DM), DM (n = 61) and normal control (n = 11) were enrolled. High-density lipoprotein (HDL) was separated from serum by the addition of sodium phosphotungstate and magnesium chloride, and the precipitated fraction was prepared as non-HDL. Phospholipids were extracted from whole serum, non-HDL and HDL to estimate PCOOH level with chemiluminescence high performance liquid chromatography (CL-HPLC). PCOOH level (nmol/l, mean +/- S.D.) was higher in DM than in control (33.1 +/- 9.5 vs. 23.0 +/- 8.2 for serum; P < 0.01, 17.0 +/- 5.5 vs. 10.6 +/- 3.8 for non-HDL; P < 0.01, and 16.1 +/- 6.3 vs. 12.3 +/- 5.5 for HDL; not significant, respectively). DM was divided into five groups according to hemoglobin A(1c) (HbA(1c)) levels (%): (1) less than 6, (2) 6-6.4, (3) 6.5-6.9 (4) 7.0-7.4, and (5) over than 7.5. Increase of PCOOH levels was dependent on HbA(1c). We concluded that (1) serum and non-HDL PCOOH increased in DM, (2) the level was strongly correlated with diabetic control, and (3) approximately a half amount of serum PCOOH was present in HDL of both control and DM.

Oxidative stress induces impairment of human erythrocyte energy metabolism through the oxygen radical-mediated direct activation of AMP-deaminase

The effect of oxidative stress on human red blood cell AMP-deaminase activity was studied by incubating either fresh erythrocytes or hemolysates with H(2)O(2) (0.5, 1, 2, 4, 6, 8, and 10 mm) or NaNO(2) (1, 5, 10, 20, and 50 mm), for 15 min at 37 degrees C. AMP-deaminase tremendously increased by increasing H(2)O(2) or NaNO(2) at up to 4 and 20 mm, respectively (maximal effect for both oxidants was 9.5 and 6.5 times higher enzymatic activity than control erythrocytes or hemolysates, respectively). The incubation of hemolysates with iodoacetate (5-100 mm), N-ethylmaleimide (0.1-10 mm), or p-hydroxymercuribenzoate (0.1-5 mm) mimicked the effect of oxidative stress on AMP-deaminase, indicating that sulfhydryl group modification is involved in the enzyme activation. In comparison with control hemolysates, changes of the kinetic properties of AMP-deaminase (decrease of AMP concentration necessary for half-maximal activation, increase of V(max), modification of the curve shape of V(o) versus [S], Hill plots, and coefficients) were recorded with 4 mm H(2)O(2)- and 1 mm N-ethylmaleimide-treated hemolysates. Data obtained using 90% purified enzyme, incubated with Fenton reagents (Fe(2+) + H(2)O(2)) or -SH-modifying compounds, demonstrated that (i) reactive oxygen species are directly responsible for AMP-deaminase activation; (ii) this phenomenon occurs through sulfhydryl group modification; and (iii) the activation does not involve the loss of the tetrameric protein structure. Results of experiments conducted with glucose-6-phosphate dehydrogenase-deficient erythrocytes, challenged with increasing doses of the anti-malarial drug quinine hydrochloride and showing dramatic AMP-deaminase activation, suggest relevant physiopathological implications of this enzymatic activation in conditions of increased oxidative stress. To the best of our knowledge, this is the first example of an enzyme, fundamental for the maintenance of the correct red blood cell energy metabolism, that is activated (rather than inhibited) by the interaction with reactive oxygen species.

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

Skin is a tissue exposed most frequently to oxidative stress from the environment in daily life. Age-related changes of oxidative damage and antioxidant enzyme activity in the skin were examined in male Fischer 344 rats aged 6 to 30 months. The contents of phosphatidylcholine hydroperoxide (PCOOH) and thiobarbituric acid-reacting substances (TBARS) increased linearly with age. The content of cholesterol hydroperoxide increased until 24 months of age and then decreased. The content of 8-oxo-2'-deoxyguanosine (8-oxodG) increased gradually with age, and was significantly higher at 30 months of age than at 6 months of age. Superoxide dismutase activity tended to decrease with age. The activities of catalase and glutathione peroxidase showed no changes with age. We examined the effect of dietary restriction on the accumulation of oxidative damage in rat skin. The increase in PCOOH content in the skin of dietary-restricted rats was suppressed until 30 months of age. The TBARS and cholesterol hydroperoxide contents in the skin of dietary-restricted rats were significantly lower than in the skin of ad libitum-fed rats, while the 8-oxodG content was somewhat lower in the dietary-restricted rats than the ad libitum-fed rats. These results indicate that oxidative damage to the lipids and DNA in rat skin increases with age and that dietary restriction delays the accumulation of oxidative damage in skin.

Enhanced level of n-3 fatty acid in membrane phospholipids induces lipid peroxidation in rats fed dietary docosahexaenoic acid oil

The effect of dietary docosahexaenoic acid (DHA, 22:6n-3) oil with different lipid types on lipid peroxidation was studied in rats. Each group of male Sprague-Dawley rats was pair fed 15% (w/w) of either DHA-triglycerides (DHA-TG), DHA-ethyl esters (DHA-EE) or DHA-phospholipids (DHA-PL) for up to 3 weeks. The palm oil (supplemented with 20% soybean oil) diet without DHA was fed as the control. Dietary DHA oils lowered plasma triglyceride concentrations in rats fed DHA-TG (by 30%), DHA-EE (by 45%) and DHA-PL (by 27%), compared to control. The incorporation of dietary DHA into plasma and liver phospholipids was more pronounced in the DHA-TG and DHA-EE group than in the DHA-PL group. However, DHA oil intake negatively influenced lipid peroxidation in both plasma and liver. Phospholipid peroxidation in plasma and liver was significantly higher than control in rats fed DHA-TG or DHA-EE, but not DHA-PL. These results are consistent with increased thiobarbituric acid reactive substances (TBARS) and decreased alpha-tocopherol levels in plasma and liver. In addition, liver microsomes from rats of each group were exposed to a mixture of chelated iron (Fe(3+)/ADP) and NADPH to determine the rate of peroxidative damage. During NADPH-dependent peroxidation of microsomes, the accumulation of phospholipid hydroperoxides, as well as TBARS, were elevated and alpha-tocopherol levels were significantly exhausted in DHA-TG and DHA-EE groups. During microsomal lipid peroxidation, there was a greater loss of n-3 fatty acids (mainly DHA) than of n-6 fatty acids, including arachidonic acid (20:4n-6). These results indicate that polyunsaturation of n-3 fatty acids is the most important target for lipid peroxidation. This suggests that the ingestion of large amounts of DHA oil enhances lipid peroxidation in the target membranes where greater amounts of n-3 fatty acids are incorporated, thereby increasing the peroxidizability and possibly accelerating the atherosclerotic process.

Fish oil diet affects on oxidative senescence of red blood cells linked to degeneration of spleen cells in mice

The effect of dietary polyunsaturated fatty acids and alpha-tocopherol supplementation on erythrocyte lipid peroxidation and immunocompetent cells in mice was studied comparatively using seven dietary oils (15% oil/diet, w/w) including fish oil rich in eicosapentaenoic acid (EPA, 20:5, n-3) and docosahexaenoic acid (DHA, 22:6, n-3). A 43% increase in spleen weight, about twice as many spleen cells and no change in the subpopulations of spleen cells, as well as a significant depression of mitogen-induced blastogenesis of both T and B cells in the spleen were observed in mice fed fish oil for 30 days in comparison with soybean oil diet-fed mice. In the fish oil diet-fed mice, membranous lipid hydroperoxide (hydroperoxides of phosphatidylcholine and phosphatidylethanolamine) accumulation as a marker of oxidative senescence in red blood cells (RBC) was 2.7-3.5 times higher than that in mice fed soybean oil, although there was no difference in the plasma phosphatidylcholine hydroperoxide concentration. In spite of the supplementation of alpha-tocopherol to up to 10 times the level in the basal diet, the degeneration of spleen cells and the stimulated oxidative senescence of RBC found by the fish oil feeding could not be prevented. The results suggest that oral intake of excess polyunsaturated fatty acids, i.e. EPA and DHA, in a fish oil diet can lead to acceleration of membrane lipid peroxidation resulting in RBC senescence linked to the lowering of immune response of spleen cells, and that supplementation of alpha-tocopherol as antioxidant does not always effectively prevent such oxidative degeneration as observed in spleen cells and RBC in vivo.

Effect of pH on lipid oxidation using trout hemolysate as a catalyst: a possible role for deoxyhemoglobin

Hemoglobin-mediated lipid oxidation was studied by adding hemolysate to washed cod muscle. Three pH values were examined (pH 7.6, 7.2, and 6.0). The lag time prior to rancidity and thiobarbituric acid reactive substance development decreased greatly as the pH was reduced (p < 0.01). Formation of methemoglobin due to autoxidation of the heme pigment was found to occur more rapidly at reduced pH. Also, the level of deoxyhemoglobin was found to sharply increase with pH reduction in the range of pH 7.6-6.0. This suggested a potential role for deoxyhemoglobin as a catalyst. ATP lowered hemoglobin oxygenation at pH 7.2. Peroxidation of linoleic acid by oxy/deoxyhemoglobin and methemoglobin was investigated at two levels of preformed lipid hydroperoxides. At a reduced level of preformed lipid hydroperoxides, oxy/deoxyhemoglobin stimulated peroxidation of linoleic acid, whereas methemoglobin did not. At the higher level of preformed lipid hydroperoxides, both oxy/deoxyhemoglobin and methemoglobin were active. This investigation suggests that reduced hemoglobins played an important role in lipid oxidation processes.

Age-related Increases in Plasma Phosphatidylcholine Hydroperoxide Concentrations in Control Subjects and Patients with Hyperlipidemia

Background: The basal lipid peroxide concentration in the plasma of patients with hyperlipidemia may be related to atherosclerosis. Quantitative determination of lipid peroxides in the plasma is an important step in the overall evaluation of the biochemical processes leading to oxidative injury. Unfortunately, the currently available methods for lipid peroxidation lack specificity and sensitivity.

Methods: Hyperlipidemic patients (44 males and 50 females), ages 12–82 years (mean ± SE, 53 ± 2.3 years for males, 58 ± 2.0 years for females, and 56 ± 14 years for total cases), and normolipidemic volunteers (controls, 32 males and 15 females), ages 13–90 years (49 ± 4 years for males, 65 ± 4 years for females, and 55 ± 24 years for total cases), were recruited in the present study. Plasma phosphatidylcholine hydroperoxide (PCOOH) was determined by chemiluminescence-HPLC (CL-HPLC).

Results: Plasma PCOOH concentrations increased with age in both controls and hyperlipidemic patients. However, the mean plasma PCOOH concentration in patients with hyperlipidemia (331 ± 19 nmol/L; n = 94) was significantly (P &lt;0.001) higher than in the controls (160 ± 65 nmol/L; n = 47). Plasma PCOOH concentrations were similar in three hyperlipidemic phenotypes: hypercholesterolemia (IIa), hypertriglyceridemia (IV), and combined hyperlipidemia (IIb). The mean plasma PCOOH in patients with treatment-induced normalized plasma lipids was 202 ± 17 nmol/L. There was no significant correlation between plasma PCOOH concentration and total cholesterol, triglycerides, or phospholipids in hyperlipidemic patients. For all subjects, there was a significantly positive correlation between plasma PCOOH and each lipid (total cholesterol, P = 0.0002; triglycerides, P = 0.0137; and phospholipids, P &lt;0.0001). Analysis of fatty acids composition of plasma phosphatidylcholine showed significantly low concentrations of n-6 fatty acids moieties (linoleic acid and arachidonic acid) in patients compared with controls.

Conclusions: Our results suggest that an increase in plasma PCOOH in patients with hyperlipidemia may be related to the development and progression of atherosclerosis, particularly in the elderly. Measurement of plasma PCOOH is useful for in vivo evaluation of oxidative stress.

Oxidative stress in the human heart is associated with changes in the antioxidative defense as shown after heart transplantation

The study was designed to demonstrate--for the first time in humans--that oxidative stress in the heart indicated by lipid peroxidation is associated with time-dependent changes in the enzymatic antioxidative defense. For this purpose, we analyzed the oxygen radical metabolism in 69 myocardial biopsies (taken between the fifth day and 6 years after transplantation) of 31 heart transplant recipients who were suspected of suffering from increased formation of oxygen radicals in the allograft. The levels of lipid peroxides (LPO), glutathione peroxidase (GSH-Px), total-, copper/zinc- and manganese superoxide dismutase (t-SOD, CuZnSOD, MnSOD) were compared in 3 post-transplantation periods (5-90 d vs. 91-365 d vs. >1 y). Significantly increased LPO levels were found (0.27+/-0.04 vs. 0. 13+/-0.02 vs. 0.27+/-0.04 nmol/mg protein) in the first and third period. Increased activities of GSH-Px (39.8+/-3.8 vs. 30.2+/-4.1 vs. 76.7+/-6.5 mU/mg protein), t-SOD (1.57+/-0.10 vs. 1.30+/-0.14 vs. 2.44+/-0.23 U/mg protein) and CuZnSOD (1.09+/-0.08 vs. 0.93+/-0.13 vs. 2.05+/-0.21 U/mg protein) occurred only in the third period. For calculation of time courses more precisely, the single data with respect to time were analyzed with a curve fitting program. Except for the first period, the allograft LPO and GSH-Px levels rose for up to 6 years after transplantation. However, the t-SOD and CuZnSOD activities switched from increase to decrease in the third period. The study provided indication for: first, the potency of the human heart to time-limited increase of the enzymatic antioxidative defense, and secondly, the inability of human heart allografts--despite this adaptation--for complete prevention of myocardial oxidative stress.

Quantitative determination of cholesterol 5alpha-, 7alpha-, and 7beta-hydroperoxides in rat skin

An assay method for determination of cholesterol 5alpha-, 7alpha-, and 7beta-hydroperoxides (ChOOHs) in rat skin using high-performance liquid chromatography (HPLC) with a chemiluminescence detector has been developed. In the assay method, free form and free plus ester forms of ChOOHs could be separately determined by HPLC in combination with the treatment of a tissue extract by cholesterol esterase. Lower limits of quantitation for cholesterol 5alpha-, 7alpha-, and 7beta-hydroperoxides were 0.2, 0.1, and 0.5 nmol/g skin, respectively. This assay method showed that (i) good absolute recoveries of ChOOHs from rat skin (80-90% of radiolabeled ChOOHs added to rat skin); (ii) negligible autoxidation of cholesterol caused by the assay procedure (<9.4x10(-5)% of radiolabeled cholesterol added to rat skin); and (iii) good correlation between ChOOHs added to rat skin and ChOOHs determined, indicating this assay method is applicable to quantify ChOOHs in rat skin. By using this assay method, we observed that (i) cholesterol 5alpha-hydroperoxide was detected in skin of rats pretreated with oral doses of pheophorbide a and subsequent visible irradiation; (ii) concentrations of cholesterol 7-hydroperoxides in skin of rats in an ambient light room were not significantly different from those in a dark room for 12 weeks; and (iii) ultraviolet light B irradiation markedly enhanced the concentrations of cholesterol 7-hydroperoxides in the skin of rats.

Chemiluminescent determination of cholesterol hydroperoxides in human erythrocyte membrane

A method for separating, detecting, and quantifying cholesterol hydroperoxide (Ch-OOH) based on extraction, purification by solid-phase extraction cartridge, high-performance liquid chromatography with chemiluminescent detection (HPLC-CL), and liquid chromatography-mass spectrometry has been developed for human erythrocyte membrane. We prepared standard compounds of the cholesterol 5alpha-, 7alpha-, and 7beta-hydroperoxides (Ch 5alpha-OOH, Ch 7alpha-OOH, and Ch 7beta-OOH). An octyl silica column with methanol/water/acetonitrile 89:9:2 (by vol) as eluent was used to determine Ch-OOH. HPLC-CL that incorporated cytochrome c and luminol as the post-column luminescent reagent was used. We also investigated the optimal assay conditions and how to prevent formation of artifact Ch-OOH. Analysis of erythrocyte membranes from seven healthy volunteers identified Ch 7alpha-OOH and Ch 7beta-OOH, but not Ch 5alpha-OOH, as commonly occurring components. The respective mean concentrations of Ch 7alpha-OOH and Ch 7beta-OOH were 2.5+/-1.6 and 5.4+/-3.5 pmol/mL blood.

Age-associated oxidative damage in microsomal and plasma membrane lipids of rat hepatocytes

Phosphatidylcholine hydroperoxide (PC-OOH) and phosphatidylethanolamine hydroperoxide (PE-OOH) concentrations were determined in microsomes and plasma membranes prepared from 2- and 17-month-old male Sprague-Dawley rat hepatocytes, to verify the dissimilarity of age dependency of lipid peroxidation in organelle membranes. The hydroperoxides were directly measured by chemiluminescence detection-high-performance liquid chromatography (CL-HPLC), and 1-palmitoyl-2-(13-hydroperoxy-cis-9, trans-11-octadecadienoyl) phosphatidylcholine (PLPC-OOH) and 1-palmitoyl-2-(13-hydroperoxy-cis-9, trans-11-octadecadienoyl) phosphatidylethanolamine (PLPE-OOH) were enzymatically synthesized and utilized as standards for the calibration. Baseline concentrations of hydroperoxides (PC-OOH + PE-OOH) of the 17-month-old rats were 46 pmol per mg protein in microsomes (2.7 times higher than the 2-month-old rats) and 306 pmol per mg protein in plasma membranes (9.9 times higher than the 2-month-old rats). Both microsomal and plasma membrane lipids were severely peroxidized and converted to phospholipid hydroperoxides by NADPH-dependent lipid peroxidation in vitro, but the age-dependency was only observed in the plasma membranes. These results demonstrate that substantial oxidative damage to membrane phospholipids occurs with ageing both in microsomes and plasma membranes, but is more prevalent in plasma membranes in rat hepatocytes.