The biochemistry of the isoprostane, neuroprostane, and isofuran Pathways of lipid peroxidation

Biomarkers of oxidative stress and reproductive complications

Oxidative stress is the result of an imbalance between the formation of reactive oxygen species (ROS) and the levels of enzymatic and non-enzymatic antioxidants. The assessment of biological redox status is performed by the use of oxidative stress biomarkers. An oxidative stress biomarker is defined as any physical structure or process or chemical compound that can be assessed in a living being (in vivo) or in solid or fluid parts thereof (in vitro), the determination of which is a reproducible and reliable indicator of oxidative stress. The use of oxidative stress biomarkers allows early identification of the risk of developing diseases associated with this process and also opens up possibilities for new treatments. At the end of the last century, interest in oxidative stress biomarkers began to grow, due to evidence of the association between the generation of free radicals and various pathologies. Up to now, a significant number of studies have been carried out to identify and apply different oxidative stress biomarkers in clinical practice. Among the most important oxidative stress biomarkers, it can be mentioned the products of oxidative modifications of lipids, proteins, nucleic acids, and uric acid as well as the measurement of the total antioxidant capacity of fluids in the human body. In this review, we aim to present recent advances and current knowledge on the main biomarkers of oxidative stress, including the discovery of new biomarkers, with emphasis on the various reproductive complications associated with variations in oxidative stress levels.

A systematic review of molecular approaches that link mitochondrial dysfunction and neuroinflammation in Parkinson's disease

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disorder that affects 1% of the population worldwide. Etiology of PD is likely to be multi-factorial such as protein misfolding, mitochondrial dysfunction, oxidative stress, and neuroinflammation that contributes to the pathology of Parkinson's disease (PD), numerous studies have shown that mitochondrial dysfunction may play a key role in the dopaminergic neuronal loss. In multiple ways, the two most important are the activation of neuroinflammation and mitochondrial dysfunction, while mitochondrial dysfunction could cause neuroinflammation and vice versa. Thus, the mitochondrial proteins are the highly promising target for the development of PD. However, the limited amount of dopaminergic neurons prevented the detailed investigation of Parkinson's disease with regard to mitochondrial dysfunction. Both genetic and environmental factors are also associated with mitochondrial dysfunction and PD pathogenesis. The induction of PD by neurotoxins that inhibit mitochondrial complex I provide direct evidence linking mitochondrial dysfunction to PD. A decrease of mitochondrial complex I activity is observed in PD brain and in neurotoxin- or genetic factor-induced in vitro and in vivo models. Moreover, PINK1, Parkin, DJ-1 and LRRK2 mitochondrial PD gene products have important roles in mitophagy, a cellular process that clear damaged mitochondria. This review paper would discuss the evidence for the mitochondrial dysfunction and neuroinflammation in PD.

Parenteral Nutrition and Oxidant Load in Neonates

Neonates with preterm, gastrointestinal dysfunction and very low birth weights are often intolerant to oral feeding. In such infants, the provision of nutrients via parenteral nutrition (PN) becomes necessary for short-term survival, as well as long-term health. However, the elemental nutrients in PN can be a major source of oxidants due to interactions between nutrients, imbalances of anti- and pro-oxidants, and environmental conditions. Moreover, neonates fed PN are at greater risk of oxidative stress, not only from dietary sources, but also because of immature antioxidant defences. Various interventions can lower the oxidant load in PN, including the supplementation of PN with antioxidant vitamins, glutathione, additional arginine and additional cysteine; reduced levels of pro-oxidant nutrients such as iron; protection from light and oxygen; and proper storage temperature. This narrative review of published data provides insight to oxidant molecules generated in PN, nutrient sources of oxidants, and measures to minimize oxidant levels.

Isofurans and Isoprostanes as Potential Markers of Delayed Cerebral Ischemia Following Aneurysmal Subarachnoid Hemorrhage: A Prospective Observational Study

BACKGROUND

F2-Isoprostanes (F2-IsoPs) and Isofurans (IsoF), specific markers of lipid peroxidation in vivo, have been reported to be elevated and have prognostic implications following subarachnoid hemorrhage (SAH). Platelet activation and vasoconstriction are attributed to these compounds. Elevated IsoF to F2-IsoPs ratios have been proposed as in vivo biomarkers of mitochondrial dysfunction. In this pilot study, we examined their performance as specific biomarkers for delayed cerebral ischemia (DCI) development following SAH.

METHODS

Eighteen patients with SAH and six controls with normal neuroimaging and cerebrospinal fluid (CSF) analysis results underwent CSF sampling and abstraction of clinical, demographic, and laboratory data. Samples (two) of CSF were collected on day 1 and once on days 5-8 post bleed. F2-IsoP and IsoF assays were performed by gas chromatography/mass spectroscopy methods. Levels are expressed in median (interquartile range) for nonnormally distributed data. Repeated sample measurements were compared using the Wilcoxon signed-rank test, whereas the Mann-Whitney U-test was used for other nonnormally distributed data.

RESULTS

Mean age was 61 ± 15.7 (SAH cases) versus 48 ± 10 (controls) years, and 80% of patients with SAH were women. Median Hunt and Hess score was 3 (2-4), and modified Fisher scale was 3 (3-4). Thirty nine percent of patients developed DCI. F2-IsoP were significantly higher in SAH cases than in controls [47.5 (30.2-53.5) vs. 26.0 (21.2-34.5) pg/mL]. No significant differences were observed in patients with or without DCI [41 (33.5-52) vs. 44 (28.5-55.5) pg/mL]. IsoF were elevated in the second CSF sample in nine patients but were undetectable in the remainder cases and all controls. Patients who developed DCI had significantly higher IsoF than those who did not [57 (34-72) vs. 0 (0-34) pg/mL]. Patients who met criteria for DCI had a significantly higher IsoF to F2IsoPs ratio on the late CSF sample [1.03 (1-1.38) vs. 0 (0-0.52)].

CONCLUSIONS

Preliminary findings from this study suggest that IsoF may represent a specific biomarker predicting DCI following SAH. Future studies to further explore the value of IsoF as biomarkers of secondary brain injury following SAH seem warranted.

Alzheimer's disease treatment: The share of herbal medicines

One of the most frequent forms of dementia in neurological disorders is Alzheimer's disease (AD). It is a chronic neurodegenerative disease characterized by impaired learning and memory. Pathological symptoms as extracellular amyloid-beta (Aβ) plaques and intracellular accumulation of neurofibrillary tangles occur in AD. Due to the aging of the population and increased prevalence of AD, discovery of new therapeutic agents with the highest effectiveness and fewer side effect seems to be necessary. Numerous synthetic medicines such as tacrine, donepezil, galantamine, rivastigmine, memantine, glutathione, ascorbic acid, ubiquinone, ibuprofen, and ladostigil are routinely used for reduction of the symptoms and prevention of disease progression. Nowadays, herbal medicines have attracted popular attention for numerous beneficial effects with little side effects. Lavandula angustifolia, Ginkgo biloba, Melissa officinalis, Crocus sativus, Ginseng, Salvia miltiorrhiza, and Magnolia officinalis have been widely used for relief of symptoms of some neurological disorders. This paper reviews the therapeutic effects of phytomedicines with prominent effects against various factors implicated in the emergence and progression of AD.

Regional differences of hypothermia on oxidative stress following hypoxia-ischemia: a study of DHA and hypothermia on brain lipid peroxidation in newborn piglets

Background Oxidative stress plays an important part in the pathophysiology of hypoxic-ischemic encephalopathy (HIE) and is reliably measured through prostanoids following lipid peroxidation of polyunsaturated fatty acids (PUFAs). The aim of the study is to measure oxidative stress in the prefrontal cortex, white matter and hippocampus in the brains of hypoxic-ischemic piglets treated with docosahexaenoic acid (DHA) and therapeutic hypothermia (TH) and investigate the additive effects of DHA on hypothermia by factorial design. Methods Fifty-five piglets were randomized as having severe global hypoxia (n=48) or not (sham, n=7). Hypoxic piglets were further randomized: vehicle (VEH), DHA, VEH+hypothermia (HT) or HT+DHA. A total of 5 mg/kg DHA was given intravenously 210 min after the end of hypoxia. Brain tissues were analyzed using liquid chromatography triple quadrupole mass spectrometry technique (LC-MS). A two-way analysis of variance (ANOVA) was performed with DHA and HT as main effects. Results In the white matter, we found main effects of DHA on DH-isoprostanes (P=0.030) and a main effect of HT on F4-neuroprostanes (F4-NeuroPs) (P=0.007), F2-isoprostanes (F2-IsoPs) (P=0.043) and DH-isoprostanes (P=0.023). In the cortex, the ANOVA analysis showed the interactions of main effects between DHA and HT for neurofuranes (NeuroFs) (P=0.092) and DH-isoprostanes (P=0.015) as DHA significantly reduced lipid peroxidation in the absence of HT. DHA compared to VEH significantly reduced NeuroFs (P=0.019) and DH-isoprostanes (P=0.010). No differences were found in the hippocampus. Conclusion After severe hypoxia, HT reduced lipid peroxidation in the white matter but not in the cortical gray matter. HT attenuated the reducing effect of DHA on lipid peroxidation in the cortex. Further studies are needed to determine whether DHA can be an effective add-on therapy for TH.

Investigation of a Thromboxane A2 Receptor-Based Vaccine for Managing Thrombogenesis

BACKGROUND

Despite the well-established role for the thromboxane A2 receptor (TPR) in the development of thrombotic disorders, none of the antagonists developed to date has been approved for clinical use. To this end, we have previously shown that an antibody targeted against TPR's ligand-binding domain inhibits platelet activation and thrombus formation, without exerting any effects on hemostasis. Thus, the goal of the present studies is to design a novel TPR-based vaccine, demonstrate its ability to trigger an immune response, and characterize its antiplatelet and antithrombotic activity.

METHODS AND RESULTS

We used a mouse keyhole limpet hemocyanin/peptide-based vaccination approach rationalized over the TPR ligand-binding domain (ie, the C-terminus of the second extracellular loop). The biological activity of this vaccine was assessed in the context of platelets and thrombotic diseases, and using a host of in vitro and in vivo platelet function experiments. Our results revealed that the TPR C-terminus of the second extracellular loop vaccine, in mice: (1) triggered an immune response, which resulted in the development of a C-terminus of the second extracellular loop antibody; (2) did not affect expression of major platelet integrins (eg, glycoprotein IIb-IIIa); (3) selectively inhibited TPR-mediated platelet aggregation, platelet-leukocyte aggregation, integrin glycoprotein IIb-IIIa activation, as well as dense and α granule release; (4) significantly prolonged thrombus formation; and (5) did so without impairing physiological hemostasis.

CONCLUSIONS

Collectively, our findings shed light on TPR's structural biological features, and demonstrate that the C-terminus of the second extracellular loop domain may define a new therapeutic target and a TPR vaccine-based approach that should have therapeutic applications.

A potential therapeutic role for angiotensin-converting enzyme 2 in human pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a deadly disease with no cure. Alternate conversion of angiotensin II (AngII) to angiotensin-(1-7) (Ang-(1-7)) by angiotensin-converting enzyme 2 (ACE2) resulting in Mas receptor (Mas1) activation improves rodent models of PAH. Effects of recombinant human (rh) ACE2 in human PAH are unknown. Our objective was to determine the effects of rhACE2 in PAH.We defined the molecular effects of Mas1 activation using porcine pulmonary arteries, measured AngII/Ang-(1-7) levels in human PAH and conducted a phase IIa, open-label pilot study of a single infusion of rhACE2 (GSK2586881, 0.2 or 0.4 mg·kg^-1 intravenously).Superoxide dismutase 2 (SOD2) and inflammatory gene expression were identified as markers of Mas1 activation. After confirming reduced plasma ACE2 activity in human PAH, five patients were enrolled in the trial. GSK2586881 was well tolerated with significant improvement in cardiac output and pulmonary vascular resistance. GSK2586881 infusion was associated with reduced plasma markers of inflammation within 2-4 h and increased SOD2 plasma protein at 2 weeks.PAH is characterised by reduced ACE2 activity. Augmentation of ACE2 in a pilot study was well tolerated, associated with improved pulmonary haemodynamics and reduced markers of oxidant and inflammatory mediators. Targeting this pathway may be beneficial in human PAH.

Oxidant-specific biomarkers of oxidative stress. Association with atherosclerosis and implication for antioxidant effects

The unregulated oxidative modification of lipids, proteins, and nucleic acids induced by multiple oxidants has been implicated in the pathogenesis of many diseases. Antioxidants with diverse functions exert their roles either directly or indirectly in the physiological defense network to inhibit such deleterious oxidative modification of biological molecules and resulting damage. The efficacy of antioxidants depends on the nature of oxidants. Therefore, it is important to identify the oxidants which are responsible for modification of biological molecules. Some oxidation products produced selectively by specific oxidant enable to identify the responsible oxidants, while other products are produced by several oxidants similarly. In this review article, several oxidant-specific products produced selectively by peroxyl radicals, peroxynitrite, hypochlorous acid, lipoxygenase, and singlet oxygen were summarized and their potential role as biomarker is discussed. It is shown that the levels of specific oxidation products including hydroxylinoleate isomers, nitrated and chlorinated products, and oxysterols produced by the above-mentioned oxidants are elevated in the human atherosclerotic lesions, suggesting that all these oxidants may contribute to the development of atherosclerosis. Further, it was shown that the reactivities of physiological antioxidants toward the above-mentioned oxidants vary extensively, suggesting that multiple antioxidants effective against these different oxidants are required, since no single antioxidant alone can cope with these multiple oxidants.

Relevance of 4-F4t-neuroprostane and 10-F4t-neuroprostane to neurological diseases

F₄-neuroprostanes (F₄-NeuroPs) are non-enzymatic oxidized products derived from docosahexaenoic acid (DHA) and are suggested to be oxidative damage biomarkers of neurological diseases. However, 128 isomers can be formed from DHA oxidation and among them, 4(RS)-4-F_4t-NeuroP (4-F_4t-NeuroP) and 10(RS)-10-F_4t-NeuroP (10-F_4t-NeuroP) are the most studied. Here, we report the identification and the clinical relevance of 4-F_4t-NeuroP and 10-F_4t-NeuroP in plasma of four different neurological diseases, including multiple sclerosis (MS), autism spectrum disorders (ASD), Rett syndrome (RTT), and Down syndrome (DS). The identification and the optimization of the method were carried out by gas chromatography/negative-ion chemical ionization tandem mass spectrometry (GC/NICI-MS/MS) using chemically synthesized 4-F_4t-NeuroP and 10-F_4t-NeuroP standards and in oxidized DHA liposome. Both 4-F_4t-NeuroP and 10-F_4t-NeuroP were detectable in all plasma samples from MS (n = 16), DS (n = 16), ASD (n = 9) and RTT (n = 20) patients. While plasma 10-F_4t-NeuroP content was significantly higher in patients of all diseases as compared to age and gender matched healthy control subjects (n = 61), 4-F_4t-NeuroP levels were significantly higher in MS and RTT as compared to healthy controls. Significant positive relationships were observed between relative disease severity and 4-F_4t-NeuroP levels (r = 0.469, P <0.0001), and 10-F_4t-NeuroP levels (r = 0.757, P < 0.0001). The study showed that the plasma amount ratio of 10-F_4t-NeuroP to 4-F_4t-NeuroP and the plasma amount as individual isomer can be used to discriminate between different brain diseases. Overall, by comparing the different types of disease, our plasma data indicates that 4-F_4t-NeuroP and 10-F_4t -NeuroP: i) are biologically synthesized in vivo and circulated, ii) are related to clinical severity of neurological diseases, iii) are useful to identify shared pathogenetic pathways in distinct brain diseases, and iv) appears to be distinctive for different neurological conditions, thus representing potentially new biological disease markers. Our data strongly suggest that in vivo DHA oxidation follows preferential chemical rearrangements according to different brain diseases.

Ischemic Retinopathies: Oxidative Stress and Inflammation

Ischemic retinopathies (IRs), such as retinopathy of prematurity (ROP), diabetic retinopathy (DR), and (in many cases) age-related macular degeneration (AMD), are ocular disorders characterized by an initial phase of microvascular changes that results in ischemia, followed by a second phase of abnormal neovascularization that may culminate into retinal detachment and blindness. IRs are complex retinal conditions in which several factors play a key role during the development of the different pathological stages of the disease. Increasing evidence reveals that oxidative stress and inflammatory processes are important contributors to the pathogenesis of IRs. Despite the beneficial effects of the photocoagulation and anti-VEGF therapy during neovascularization phase, the need to identify novel targets to prevent initial phases of these ocular pathologies is still needed. In this review, we provide an update on the involvement of oxidative stress and inflammation in the progression of IRs and address some therapeutic interventions by using antioxidants and anti-inflammatory agents.

Hyperbaric oxygen therapy is not associated with oxidative stress assessed using plasma F2-isoprostanes and isofurans

BACKGROUND AND AIMS

Hyperbaric oxygen (HBO) therapy is increasingly used in medical practice as a means of enhancing the formation of collagen matrix and angiogenesis, thus promoting healing in wounds and necrotic tissue. However, there are concerns that oxygen can also associate with increased production of oxygen free radicals and oxidative stress. F₂-Isoprostanes (F₂-IsoPs) formed by non-enzymatic oxidation of arachidonic acid (AA) are reliable measures for assessing oxidative stress in vivo. In addition, under conditions of high oxygen tension isofurans (IsoFs) are preferentially formed from AA and are considered to better reflect oxidative stress in the setting of high oxygen tension. This study aimed to measure plasma IsoFs and F₂-IsoP in patients receiving HBO therapy to treat osteonecrosis secondary to radiation therapy. Our hypothesis was that IsoFs would continue to rise with increasing oxygen pressures in contrast to F₂-IsoPs whose synthesis would be reduced.

METHODS

Twelve patients receiving hyperbaric therapy to treat osteonecrosis secondary to radiation therapy were studied during hyperbaric treatment. Blood samples were collected prior to, during and after cessation of HBO therapy that lasted for 119min. Seven serial blood samples were collected for measurement of plasma F₂-IsoPs and IsoFs, blood gases and haemoglobin.

RESULTS

Oxygen saturation and venous oxygen partial pressure (PvO₂) rose significantly during hyperbaric therapy. However, there were no significant changes in plasma IsoFs or F₂-IsoPs during the hyperbaric therapy session.

CONCLUSION

In this study of patients with osteonecrosis, HBO therapy at a maximum pressure of 2.4atm with up to 100% oxygen did not worsen oxidative stress assessed using plasma F₂- IsoFs and IsoPs.

Omega-3 Polyunsaturated Fatty Acids and Oxylipins in Neuroinflammation and Management of Alzheimer Disease

Alzheimer disease (AD) is becoming one of the most prevalent neurodegenerative conditions worldwide. Although the disease progression is becoming better understood, current medical interventions can only ameliorate some of the symptoms but cannot slow disease progression. Neuroinflammation plays an important role in the advancement of this disorder, and n-3 (ω-3) polyunsaturated fatty acids (PUFAs) are involved in both the reduction in and resolution of inflammation. These effects may be mediated by the anti-inflammatory and proresolving effects of bioactive lipid mediators (oxylipins) derived from n-3 PUFAs [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] in fish oil. Although interventions have generally used fish oil containing both EPA and DHA, several studies that used either EPA or DHA alone or specific oxylipins derived from these fatty acids indicate that they have distinct effects. Both DHA and EPA can reduce neuroinflammation and cognitive decline, but EPA positively influences mood disorders, whereas DHA maintains normal brain structure. Fewer studies with a plant-derived n-3 PUFA, α-linolenic acid, suggest that other n-3 PUFAs and their oxylipins also may positively affect AD. Further research identifying the unique anti-inflammatory and proresolving properties of oxylipins from individual n-3 PUFAs will enable the discovery of novel disease-management strategies in AD.

Targeting Oxidative Stress in Central Nervous System Disorders

There is widespread recognition that reactive oxygen species (ROS) play key roles in normal brain function and pathology in the context of neurological disease. Oxidative stress continues to be a key therapeutic target for neurological diseases. In developing antioxidant therapies for neurological disease, special attention should be given to the brain's unique vulnerability to oxidative insults and its architecture. Consideration of antioxidant therapy should be guided by a strong rationale for oxidative stress in a given neurological disease. This review provides an overview of processes that can guide the development of antioxidant therapies in neurological diseases, such as knowledge of basic redox mechanisms, unique features of brain pathophysiology, mechanisms and classes of antioxidants, and desirable properties of drug candidates.

Prenatal exposure to the organophosphate insecticide chlorpyrifos enhances brain oxidative stress and prostaglandin E2 synthesis in a mouse model of idiopathic autism

BACKGROUND

Autism spectrum disorders (ASD) are emerging as polygenic and multifactorial disorders in which complex interactions between defective genes and early exposure to environmental stressors impact on the correct neurodevelopment and brain processes. Organophosphate insecticides, among which chlorpyrifos (CPF), are widely diffused environmental toxicants associated with neurobehavioral deficits and increased risk of ASD occurrence in children. Oxidative stress and dysregulated immune responses are implicated in both organophosphate neurodevelopmental effects and ASD etiopathogenesis. BTBR T+tf/J mice, a well-studied model of idiopathic autism, show several behavioral and immunological alterations found in ASD children, and we recently showed that CPF gestational exposure strengthened some of these autistic-like traits. In the present study, we aimed at investigating whether the behavioral effects of gestational CPF administration are associated with brain increased oxidative stress and altered lipid mediator profile.

METHODS

Brain levels of F2-isoprostanes (15-F2t-IsoP), as index of in vivo oxidative stress, and prostaglandin E2 (PGE2), a major arachidonic acid metabolite released by immune cells and by specific glutamatergic neuron populations mainly in cortex and hippocampus, were assessed by specific enzyme-immuno assays in brain homogenates from BTBR T+tf/J and C57Bl6/J mice, exposed during gestation to either vehicle or CPF. Measures were performed in mice of both sexes, at different postnatal stages (PNDs 1, 21, and 70).

RESULTS

At birth, BTBR T+tf/J mice exhibited higher baseline 15-F2t-IsoP levels as compared to C57Bl6/J mice, suggestive of greater oxidative stress processes. Gestational treatment with CPF-enhanced 15-F2t-IsoP and PGE2 levels in strain- and age-dependent manner, with 15-F2t-IsoP increased in BTBR T+tf/J mice at PNDs 1 and 21, and PGE2 elevated in BTBR T+tf/J mice at PNDs 21 and 70. At PND 21, CPF effects were sex-dependent being the increase of the two metabolites mainly associated with male mice. CPF treatment also induced a reduction of somatic growth, which reached statistical significance at PND 21.

CONCLUSIONS

These findings indicate that the autistic-like BTBR T+tf/J strain is highly vulnerable to environmental stressors during gestational period. The results further support the hypothesis that oxidative stress might be the link between environmental neurotoxicants such as CPF and ASD. The increased levels of oxidative stress during early postnatal life could result in delayed and long-lasting alterations in specific pathways relevant to ASD, of which PGE2 signaling represents an important one.

Clinical Relevance of Biomarkers of Oxidative Stress

SIGNIFICANCE

Oxidative stress is considered to be an important component of various diseases. A vast number of methods have been developed and used in virtually all diseases to measure the extent and nature of oxidative stress, ranging from oxidation of DNA to proteins, lipids, and free amino acids.

RECENT ADVANCES

An increased understanding of the biology behind diseases and redox biology has led to more specific and sensitive tools to measure oxidative stress markers, which are very diverse and sometimes very low in abundance.

CRITICAL ISSUES

The literature is very heterogeneous. It is often difficult to draw general conclusions on the significance of oxidative stress biomarkers, as only in a limited proportion of diseases have a range of different biomarkers been used, and different biomarkers have been used to study different diseases. In addition, biomarkers are often measured using nonspecific methods, while specific methodologies are often too sophisticated or laborious for routine clinical use.

FUTURE DIRECTIONS

Several markers of oxidative stress still represent a viable biomarker opportunity for clinical use. However, positive findings with currently used biomarkers still need to be validated in larger sample sizes and compared with current clinical standards to establish them as clinical diagnostics. It is important to realize that oxidative stress is a nuanced phenomenon that is difficult to characterize, and one biomarker is not necessarily better than others. The vast diversity in oxidative stress between diseases and conditions has to be taken into account when selecting the most appropriate biomarker.

Nonenzymatic lipid mediators, neuroprostanes, exert the antiarrhythmic properties of docosahexaenoic acid

Neuroprostanes are lipid mediators produced by nonenzymatic free radical peroxidation of docosahexaenoic acid (DHA). DHA is associated with a lower atherosclerosis risk, suggesting a beneficial role in cardiovascular diseases. The aim of this study was to investigate the influence of DHA peroxidation on its potentially antiarrhythmic properties (AAP) in isolated ventricular cardiomyocytes and in vivo in post-myocardial infarcted mice. Calcium imaging and biochemical experiments indicate that cardiac arrhythmias induced by isoproterenol are associated with Ca(2+) leak from the sarcoplasmic reticulum after oxidation and phosphorylation of the type 2 ryanodine receptor (RyR2) leading to dissociation of the FKBP12.6/RyR2 complex. Both oxidized DHA and 4(RS)-4-F4t-NeuroP prevented cellular arrhythmias and posttranslational modifications of the RyR2 leading to a stabilized FKBP12.6/RyR2 complex. DHA per se did not have AAP. The AAP of 4(RS)-4-F4t-NeuroP was also observed in vivo. In this study, we challenged the paradigm that spontaneously formed oxygenated metabolites of lipids are undesirable as they are unconditionally toxic. This study reveals that the lipid mediator 4(RS)-4-F4t-neuroprostane derived from nonenzymatic peroxidation of docosahexaenoic acid can counteract such deleterious effects through cardiac antiarrhythmic properties. Our findings demonstrate 4(RS)-4-F4t-NeuroP as a mediator of the cardioprotective AAP of DHA. This discovery opens new perspectives for products of nonenzymatic oxidized ω3 polyunsaturated fatty acids as potent mediators in diseases that involve ryanodine complex destabilization such as ischemic events.

Nonenzymatic oxygenated metabolites of α-linolenic acid B1- and L1-phytoprostanes protect immature neurons from oxidant injury and promote differentiation of oligodendrocyte progenitors through PPAR-γ activation

Phytoprostanes (PhytoP's) are formed in higher plants from α-linolenic acid via a nonenzymatic free radical-catalyzed pathway and act as endogenous mediators capable of protecting cells from damage under various conditions related to oxidative stress. Humans are exposed to PhytoP's, as they are present in relevant quantities in vegetable food and pollen. The uptake of PhytoP's through the olfactory epithelium of the nasal mucosa, upon pollen grain inhalation, is of interest as the intranasal pathway is regarded as a direct route of communication between the environment and the brain. On this basis, we sought to investigate the potential activities of PhytoP's on immature cells of the central nervous system, which are particularly susceptible to oxidative stress. In neuroblastoma SH-SY5Y cells, used as a model for undifferentiated neurons, B1-PhytoP's, but not F1-PhytoP's, increased cell metabolic activity and protected them from oxidant damage caused by H2O2. Moreover, B1-PhytoP's induced a moderate depolarization of the mitochondrial inner membrane potential. These effects were prevented by the PPAR-γ antagonist GW9662. When SH-SY5Y cells were induced to differentiate toward a more mature phenotype, they became resistant to B1-PhytoP activities. B1-PhytoP's also influenced immature cells of an oligodendroglial line, as they increased the metabolic activity of oligodendrocyte progenitors and strongly accelerated their differentiation to immature oligodendrocytes, through mechanisms at least partially dependent on PPAR-γ activity. However, B1-PhytoP's did not protect oligodendrocyte progenitors against oxidant injury. Taken together, these data suggest that B1-PhytoP's, through novel mechanisms involving PPAR-γ, can specifically affect immature brain cells, such as neuroblasts and oligodendrocyte progenitors, thereby conferring neuroprotection against oxidant injury and promoting myelination.

Lipid peroxidation: production, metabolism, and signaling mechanisms of malondialdehyde and 4-hydroxy-2-nonenal

Lipid peroxidation can be described generally as a process under which oxidants such as free radicals attack lipids containing carbon-carbon double bond(s), especially polyunsaturated fatty acids (PUFAs). Over the last four decades, an extensive body of literature regarding lipid peroxidation has shown its important role in cell biology and human health. Since the early 1970s, the total published research articles on the topic of lipid peroxidation was 98 (1970-1974) and has been increasing at almost 135-fold, by up to 13165 in last 4 years (2010-2013). New discoveries about the involvement in cellular physiology and pathology, as well as the control of lipid peroxidation, continue to emerge every day. Given the enormity of this field, this review focuses on biochemical concepts of lipid peroxidation, production, metabolism, and signaling mechanisms of two main omega-6 fatty acids lipid peroxidation products: malondialdehyde (MDA) and, in particular, 4-hydroxy-2-nonenal (4-HNE), summarizing not only its physiological and protective function as signaling molecule stimulating gene expression and cell survival, but also its cytotoxic role inhibiting gene expression and promoting cell death. Finally, overviews of in vivo mammalian model systems used to study the lipid peroxidation process, and common pathological processes linked to MDA and 4-HNE are shown.

Lipid peroxidation: production, metabolism, and signaling mechanisms of malondialdehyde and 4-hydroxy-2-nonenal

Lipid peroxidation can be described generally as a process under which oxidants such as free radicals attack lipids containing carbon-carbon double bond(s), especially polyunsaturated fatty acids (PUFAs). Over the last four decades, an extensive body of literature regarding lipid peroxidation has shown its important role in cell biology and human health. Since the early 1970s, the total published research articles on the topic of lipid peroxidation was 98 (1970-1974) and has been increasing at almost 135-fold, by up to 13165 in last 4 years (2010-2013). New discoveries about the involvement in cellular physiology and pathology, as well as the control of lipid peroxidation, continue to emerge every day. Given the enormity of this field, this review focuses on biochemical concepts of lipid peroxidation, production, metabolism, and signaling mechanisms of two main omega-6 fatty acids lipid peroxidation products: malondialdehyde (MDA) and, in particular, 4-hydroxy-2-nonenal (4-HNE), summarizing not only its physiological and protective function as signaling molecule stimulating gene expression and cell survival, but also its cytotoxic role inhibiting gene expression and promoting cell death. Finally, overviews of in vivo mammalian model systems used to study the lipid peroxidation process, and common pathological processes linked to MDA and 4-HNE are shown.

Lipid peroxidation: production, metabolism, and signaling mechanisms of malondialdehyde and 4-hydroxy-2-nonenal

Lipid peroxidation can be described generally as a process under which oxidants such as free radicals attack lipids containing carbon-carbon double bond(s), especially polyunsaturated fatty acids (PUFAs). Over the last four decades, an extensive body of literature regarding lipid peroxidation has shown its important role in cell biology and human health. Since the early 1970s, the total published research articles on the topic of lipid peroxidation was 98 (1970-1974) and has been increasing at almost 135-fold, by up to 13165 in last 4 years (2010-2013). New discoveries about the involvement in cellular physiology and pathology, as well as the control of lipid peroxidation, continue to emerge every day. Given the enormity of this field, this review focuses on biochemical concepts of lipid peroxidation, production, metabolism, and signaling mechanisms of two main omega-6 fatty acids lipid peroxidation products: malondialdehyde (MDA) and, in particular, 4-hydroxy-2-nonenal (4-HNE), summarizing not only its physiological and protective function as signaling molecule stimulating gene expression and cell survival, but also its cytotoxic role inhibiting gene expression and promoting cell death. Finally, overviews of in vivo mammalian model systems used to study the lipid peroxidation process, and common pathological processes linked to MDA and 4-HNE are shown.

Lipid peroxidation: production, metabolism, and signaling mechanisms of malondialdehyde and 4-hydroxy-2-nonenal

Lipid peroxidation can be described generally as a process under which oxidants such as free radicals attack lipids containing carbon-carbon double bond(s), especially polyunsaturated fatty acids (PUFAs). Over the last four decades, an extensive body of literature regarding lipid peroxidation has shown its important role in cell biology and human health. Since the early 1970s, the total published research articles on the topic of lipid peroxidation was 98 (1970-1974) and has been increasing at almost 135-fold, by up to 13165 in last 4 years (2010-2013). New discoveries about the involvement in cellular physiology and pathology, as well as the control of lipid peroxidation, continue to emerge every day. Given the enormity of this field, this review focuses on biochemical concepts of lipid peroxidation, production, metabolism, and signaling mechanisms of two main omega-6 fatty acids lipid peroxidation products: malondialdehyde (MDA) and, in particular, 4-hydroxy-2-nonenal (4-HNE), summarizing not only its physiological and protective function as signaling molecule stimulating gene expression and cell survival, but also its cytotoxic role inhibiting gene expression and promoting cell death. Finally, overviews of in vivo mammalian model systems used to study the lipid peroxidation process, and common pathological processes linked to MDA and 4-HNE are shown.

Lipid peroxidation: production, metabolism, and signaling mechanisms of malondialdehyde and 4-hydroxy-2-nonenal

Lipid peroxidation can be described generally as a process under which oxidants such as free radicals attack lipids containing carbon-carbon double bond(s), especially polyunsaturated fatty acids (PUFAs). Over the last four decades, an extensive body of literature regarding lipid peroxidation has shown its important role in cell biology and human health. Since the early 1970s, the total published research articles on the topic of lipid peroxidation was 98 (1970-1974) and has been increasing at almost 135-fold, by up to 13165 in last 4 years (2010-2013). New discoveries about the involvement in cellular physiology and pathology, as well as the control of lipid peroxidation, continue to emerge every day. Given the enormity of this field, this review focuses on biochemical concepts of lipid peroxidation, production, metabolism, and signaling mechanisms of two main omega-6 fatty acids lipid peroxidation products: malondialdehyde (MDA) and, in particular, 4-hydroxy-2-nonenal (4-HNE), summarizing not only its physiological and protective function as signaling molecule stimulating gene expression and cell survival, but also its cytotoxic role inhibiting gene expression and promoting cell death. Finally, overviews of in vivo mammalian model systems used to study the lipid peroxidation process, and common pathological processes linked to MDA and 4-HNE are shown.

Lipid peroxidation: production, metabolism, and signaling mechanisms of malondialdehyde and 4-hydroxy-2-nonenal

Lipid peroxidation can be described generally as a process under which oxidants such as free radicals attack lipids containing carbon-carbon double bond(s), especially polyunsaturated fatty acids (PUFAs). Over the last four decades, an extensive body of literature regarding lipid peroxidation has shown its important role in cell biology and human health. Since the early 1970s, the total published research articles on the topic of lipid peroxidation was 98 (1970-1974) and has been increasing at almost 135-fold, by up to 13165 in last 4 years (2010-2013). New discoveries about the involvement in cellular physiology and pathology, as well as the control of lipid peroxidation, continue to emerge every day. Given the enormity of this field, this review focuses on biochemical concepts of lipid peroxidation, production, metabolism, and signaling mechanisms of two main omega-6 fatty acids lipid peroxidation products: malondialdehyde (MDA) and, in particular, 4-hydroxy-2-nonenal (4-HNE), summarizing not only its physiological and protective function as signaling molecule stimulating gene expression and cell survival, but also its cytotoxic role inhibiting gene expression and promoting cell death. Finally, overviews of in vivo mammalian model systems used to study the lipid peroxidation process, and common pathological processes linked to MDA and 4-HNE are shown.

Redox imbalance and morphological changes in skin fibroblasts in typical Rett syndrome

Evidence of oxidative stress has been reported in the blood of patients with Rett syndrome (RTT), a neurodevelopmental disorder mainly caused by mutations in the gene encoding the Methyl-CpG-binding protein 2. Little is known regarding the redox status in RTT cellular systems and its relationship with the morphological phenotype. In RTT patients (n = 16) we investigated four different oxidative stress markers, F2-Isoprostanes (F2-IsoPs), F4-Neuroprostanes (F4-NeuroPs), nonprotein bound iron (NPBI), and (4-HNE PAs), and glutathione in one of the most accessible cells, that is, skin fibroblasts, and searched for possible changes in cellular/intracellular structure and qualitative modifications of synthesized collagen. Significantly increased F4-NeuroPs (12-folds), F2-IsoPs (7.5-folds) NPBI (2.3-folds), 4-HNE PAs (1.48-folds), and GSSG (1.44-folds) were detected, with significantly decreased GSH (-43.6%) and GSH/GSSG ratio (-3.05 folds). A marked dilation of the rough endoplasmic reticulum cisternae, associated with several cytoplasmic multilamellar bodies, was detectable in RTT fibroblasts. Colocalization of collagen I and collagen III, as well as the percentage of type I collagen as derived by semiquantitative immunofluorescence staining analyses, appears to be significantly reduced in RTT cells. Our findings indicate the presence of a redox imbalance and previously unrecognized morphological skin fibroblast abnormalities in RTT patients.

Lipid peroxidation: production, metabolism, and signaling mechanisms of malondialdehyde and 4-hydroxy-2-nonenal

Lipid peroxidation can be described generally as a process under which oxidants such as free radicals attack lipids containing carbon-carbon double bond(s), especially polyunsaturated fatty acids (PUFAs). Over the last four decades, an extensive body of literature regarding lipid peroxidation has shown its important role in cell biology and human health. Since the early 1970s, the total published research articles on the topic of lipid peroxidation was 98 (1970-1974) and has been increasing at almost 135-fold, by up to 13165 in last 4 years (2010-2013). New discoveries about the involvement in cellular physiology and pathology, as well as the control of lipid peroxidation, continue to emerge every day. Given the enormity of this field, this review focuses on biochemical concepts of lipid peroxidation, production, metabolism, and signaling mechanisms of two main omega-6 fatty acids lipid peroxidation products: malondialdehyde (MDA) and, in particular, 4-hydroxy-2-nonenal (4-HNE), summarizing not only its physiological and protective function as signaling molecule stimulating gene expression and cell survival, but also its cytotoxic role inhibiting gene expression and promoting cell death. Finally, overviews of in vivo mammalian model systems used to study the lipid peroxidation process, and common pathological processes linked to MDA and 4-HNE are shown.

Isoprostanes and neuroprostanes as biomarkers of oxidative stress in neurodegenerative diseases

Accumulating data shows that oxidative stress plays a crucial role in neurodegenerative disorders. The literature data indicate that in vivo or postmortem cerebrospinal fluid and brain tissue levels of F2-isoprostanes (F2-IsoPs) especially F4-neuroprotanes (F4-NPs) are significantly increased in some neurodegenerative diseases: multiple sclerosis, Alzheimer's disease, Huntington's disease, and Creutzfeldt-Jakob disease. Central nervous system is the most metabolically active organ of the body characterized by high requirement for oxygen and relatively low antioxidative activity, what makes neurons and glia highly susceptible to destruction by reactive oxygen/nitrogen species and neurodegeneration. The discovery of F2-IsoPs and F4-NPs as markers of lipid peroxidation caused by the free radicals has opened up new areas of investigation regarding the role of oxidative stress in the pathogenesis of human neurodegenerative diseases. This review focuses on the relationship between F2-IsoPs and F4-NPs as biomarkers of oxidative stress and neurodegenerative diseases. We summarize the knowledge of these novel biomarkers of oxidative stress and the advantages of monitoring their formation to better define the involvement of oxidative stress in neurological diseases.

Lipid-metabolizing CYPs in the regulation and dysregulation of metabolism

The cytochrome P450s (CYPs) represent a highly divergent class of enzymes involved in the oxidation of organic compounds. A subgroup of CYPs metabolize ω3-arachidonic and linoleic acids and ω6-docosahexaenoic and eicosapentaenoic polyunsaturated fatty acids (PUFAs) into a series of related biologically active mediators. Over the past 20 years, increasing evidence has emerged for a role of these PUFA-derived mediators in physiological and pathophysiological processes in the vasculature, during inflammation, and in the regulation of metabolism. With recent technological advances and increased availability of lipid mass spectroscopy, we are now starting to discern the patterns of these CYP-PUFA products in health and disease. These analyses not only are revealing the diverse spectrum of lipid nutrients regulated by CYPs, but also clearly indicate that the balance of these mediators changes with dietary intake of different PUFA classes. These findings suggest that we are only just beginning to understand all of the relevant lipid species produced by CYP pathways. Moreover, we are still a long way from understanding the nature and presence of their receptors, their tissue expression, and the pathophysiological processes they regulate. This review highlights these future issues in the context of lipid-metabolizing CYP enzymes, focusing particularly on the CYP450 family of epoxygenases and the lipid mediators they produce.

Lipid peroxidation generates biologically active phospholipids including oxidatively N-modified phospholipids

Peroxidation of membranes and lipoproteins converts "inert" phospholipids into a plethora of oxidatively modified phospholipids (oxPL) that can act as signaling molecules. In this review, we will discuss four major classes of oxPL: mildly oxygenated phospholipids, phospholipids with oxidatively truncated acyl chains, phospholipids with cyclized acyl chains, and phospholipids that have been oxidatively N-modified on their headgroups by reactive lipid species. For each class of oxPL we will review the chemical mechanisms of their formation, the evidence for their formation in biological samples, the biological activities and signaling pathways associated with them, and the catabolic pathways for their elimination. We will end by briefly highlighting some of the critical questions that remain about the role of oxPL in physiology and disease.

Lipid peroxidation triggers neurodegeneration: a redox proteomics view into the Alzheimer disease brain

Lipid peroxidation involves a cascade of reactions in which production of free radicals occurs selectively in the lipid components of cellular membranes. Polyunsaturated fatty acids easily undergo lipid peroxidation chain reactions, which, in turn, lead to the formation of highly reactive electrophilic aldehydes. Among these, the most abundant aldehydes are 4-hydroxy-2-nonenal (HNE) and malondialdehyde, while acrolein is the most reactive. Proteins are susceptible to posttranslational modifications caused by aldehydes binding covalently to specific amino acid residues, in a process called Michael adduction, and these types of protein adducts, if not efficiently removed, may be, and generally are, dangerous for cellular homeostasis. In the present review, we focused the discussion on the selective proteins that are identified, by redox proteomics, as selective targets of HNE modification during the progression and pathogenesis of Alzheimer disease (AD). By comparing results obtained at different stages of the AD, it may be possible to identify key biochemical pathways involved and ideally identify therapeutic targets to prevent, delay, or treat AD.

Lipidomics of oxidized polyunsaturated fatty acids

Lipid mediators are produced from the oxidation of polyunsaturated fatty acids through enzymatic and free radical-mediated reactions. When subject to oxygenation via cyclooxygenases, lipoxygenases, and cytochrome P450 monooxygenases, polyunsaturated fatty acids give rise to an array of metabolites including eicosanoids, docosanoids, and octadecanoids. These potent bioactive lipids are involved in many biochemical and signaling pathways, with inflammation being of particular importance. Moreover, because they are produced by more than one pathway and substrate, and are present in a variety of biological milieus, their analysis is not always possible with conventional assays. Liquid chromatography coupled to electrospray mass spectrometry offers a versatile and sensitive approach for the analysis of bioactive lipids, allowing specific and accurate quantitation of multiple species present in the same sample. Here we explain the principles of this approach to mediator lipidomics and present detailed protocols for the assay of enzymatically produced oxygenated metabolites of polyunsaturated fatty acids that can be tailored to answer biological questions or facilitate assessment of nutritional and pharmacological interventions.

Isoprostanes and neuroprostanes: total synthesis, biological activity and biomarkers of oxidative stress in humans

Isoprostanes (IsoPs) and neuroprostanes (NeuroPs) are formed in vivo by a free radical non-enzymatic mechanism involving peroxidation of arachidonic acid (AA, C20:4 n-6) and docosahexaenoic acid (DHA, C22:6 n-3) respectively. This review summarises our research in the total synthesis of these lipid metabolites, as well as their biological activities and their utility as biomarkers of oxidative stress in humans.

Fatty acid receptor Gpr40 mediates neuromicrovascular degeneration induced by transarachidonic acids in rodents

OBJECTIVE

Nitro-oxidative stress exerts a significant role in the genesis of hypoxic-ischemic (HI) brain injury. We previously reported that the ω-6 long chain fatty acids, transarachidonic acids (TAAs), which are nitrative stress-induced nonenzymatically generated arachidonic acid derivatives, trigger selective microvascular endothelial cell death in neonatal neural tissue. The primary molecular target of TAAs remains unidentified. GPR40 is a G protein-coupled receptor activated by long chain fatty acids, including ω-6; it is highly expressed in brain, but its functions in this tissue are largely unknown. We hypothesized that TAAs play a significant role in neonatal HI-induced cerebral microvascular degeneration through GPR40 activation.

APPROACH AND RESULTS

Within 24 hours of a HI insult to postnatal day 7 rat pups, a cerebral infarct and a 40% decrease in cerebrovascular density was observed. These effects were associated with an increase in nitrative stress markers (3-nitrotyrosine immunoreactivity and TAA levels) and were reduced by treatment with nitric oxide synthase inhibitor. GPR40 was expressed in rat pup brain microvasculature. In vitro, in GPR40-expressing human embryonic kidney (HEK)-293 cells, [(14)C]-14E-AA (radiolabeled TAA) bound specifically, and TAA induced calcium transients, extracellular signal-regulated kinase 1/2 phosphorylation, and proapoptotic thrombospondin-1 expression. In vivo, intracerebroventricular injection of TAAs triggered thrombospondin-1 expression and cerebral microvascular degeneration in wild-type mice, but not in GPR40-null congeners. Additionally, HI-induced neurovascular degeneration and cerebral infarct were decreased in GPR40-null mice.

CONCLUSIONS

GPR40 emerges as the first identified G protein-coupled receptor conveying actions of nonenzymatically generated nitro-oxidative products, specifically TAAs, and is involved in (neonatal) HI encephalopathy.

LC-MS/MS Determination of Isoprostanes in Plasma Samples Collected from Mice Exposed to Doxorubicin or Tert-Butyl Hydroperoxide

Isoprostanes are stable products of arachidonic acid peroxidation and are regarded as the most reliable markers of oxidative stress in vivo. Here we describe the LC-MS/MS procedure enabling simultaneous determination of four regioisomers (8-iso prostaglandin F2α, 8-iso-15(R)-prostaglandin F2α, 11β-prostaglandin F2α, 15(R)-prostaglandin F2α) in plasma samples collected from mice. The four plasma isoprostanes are determined by LC-ESI-MS/MS with deuterated 8-iso-PGF2α-d4 as an internal standard (I.S.). For plasma samples spiked with the isoprostanes at a level of 200 pg/mL each, the method imprecision has been below 7.1% and mean inaccuracy equaled 8.7%. The applicability of the proposed approach has been verified by the assessment of changes in isoprostane levels in plasma samples derived from mice exposed to tert-butyl hydroperoxide (TBHP), a model inducer of oxidative stress, or to antitumor drug doxorubicin (DOX) known for potent stimulation of redox cycling. Compared to the control group of mice, both oxidative stress inducers tested increased the levels of three out of four isoprostanes in exposed animals; 11β-prostaglandin F2α being the exception. The greatest rise was observed in the case of 15(R)-prostaglandin F2α, by about 50% and 70% in plasma samples derived from mice exposed to DOX and TBHP, respectively.

Lipid peroxidation biomarkers for evaluating oxidative stress and assessing antioxidant capacity in vivo

Recently, the biological roles of lipid peroxidation products have received a great deal of attention not only for elucidating pathological mechanisms but also for practical clinical applications as biomarkers. In the last 50 years, lipid peroxidation has been the subject of extensive studies from the viewpoints of mechanisms, dynamics, product analysis, involvement in diseases, inhibition, and biological signaling. Lipid hydroperoxides are formed as major primary products, but they are substrates for various enzymes and they also undergo various secondary reactions. During this decade, hydroxyoctadecadienoic acid from linoleates, F₂-isoprostanes from arachidonates, and neuroprostanes from docosahexanoates have been proposed as biomarkers for evaluating oxidative stress in vivo and its related diseases. The implications of lipid peroxidation products in vivo will be briefly reviewed and their practical applications will be discussed.

Resuscitation with supplementary oxygen induces oxidative injury in the cerebral cortex

Isoprostanes, neuroprostanes, isofurans, and neurofurans have all become attractive biomarkers of oxidative damage and lipid peroxidation in brain tissue. Asphyxia and subsequent reoxygenation cause a burst of oxygen free radicals. Isoprostanes and isofurans are generated by free radical attacks of esterified arachidonic acid. Neuroprostanes and neurofurans are derived from the peroxidation of docosahexanoic acid, which is abundant in neurons and could therefore more selectively represent oxidative brain injury. Newborn piglets (age 12-36 h) underwent hypoxia until the base excess reached -20 mmol/L or the mean arterial blood pressure dropped below 15 mm Hg. They were randomly assigned to receive resuscitation with 21, 40, or 100% oxygen for 30 min and then ventilation with air. The levels of isoprostanes, isofurans, neuroprostanes, and neurofurans were determined in brain tissue (ng/g) isolated from the prefrontal cortex using gas chromatography-mass spectrometry (GC/MS) with negative ion chemical ionization (NICI) techniques. A control group underwent the same procedures and observations but was not submitted to hypoxia or hyperoxia. Hypoxia and reoxygenation significantly increased the levels of isoprostanes, isofurans, neuroprostanes, and neurofurans in the cerebral cortex. Nine hours after resuscitation with 100% oxygen for 30 min, there was nearly a 4-fold increase in the levels of isoprostanes and isofurans compared to the control group (P=0.007 and P=0.001) and more than a 2-fold increase in neuroprostane levels (P=0.002). The levels of neuroprostanes and neurofurans were significantly higher in the piglets that were resuscitated with supplementary oxygen (40 and 100%) compared to the group treated with air (21%). The significance levels of the observed differences in neuroprostanes for the 21% vs 40% comparison and the 21% vs 100% comparison were P<0.001 and P=0.001, respectively. For neurofurans, the P values of the 21% vs 40% comparison and the 21% vs 100% comparison were P=0.036 and P=0.025, respectively. Supplementary oxygen used for the resuscitation of newborns increases lipid peroxidation in brain cortical neurons, a result that is indicative of oxidative brain damage. These novel findings provide new knowledge regarding the relationships between oxidative brain injury and resuscitation with oxygen.

Metabolic multianalyte microphysiometry reveals extracellular acidosis is an essential mediator of neuronal preconditioning

Metabolic adaptation to stress is a crucial yet poorly understood phenomenon, particularly in the central nervous system (CNS). The ability to identify essential metabolic events which predict neuronal fate in response to injury is critical to developing predictive markers of outcome, for interpreting CNS spectroscopic imaging, and for providing a richer understanding of the relevance of clinical indices of stress which are routinely collected. In this work, real-time multianalyte microphysiometry was used to dynamically assess multiple markers of aerobic and anaerobic respiration through simultaneous electrochemical measurement of extracellular glucose, lactate, oxygen, and acid. Pure neuronal cultures and mixed cultures of neurons and glia were compared following a 90 min exposure to aglycemia. This stress was cytotoxic to neurons yet resulted in no appreciable increase in cell death in age-matched mixed cultures. The metabolic profile of the cultures was similar in that aglycemia resulted in decreases in extracellular acidification and lactate release in both pure neurons and mixed cultures. However, oxygen consumption was only diminished in the neuron enriched cultures. The differences became more pronounced when cells were returned to glucose-containing media upon which extracellular acidification and oxygen consumption never returned to baseline in cells fated to die. Taken together, these data suggest that lactate release is not predictive of neuronal survival. Moreover, they reveal a previously unappreciated relationship of astrocytes in maintaining oxygen uptake and a correlation between metabolic recovery of neurons and extracellular acidification.

Understanding secondary injury

Secondary injury is a term applied to the destructive and self-propagating biological changes in cells and tissues that lead to their dysfunction or death over hours to weeks after the initial insult (the "primary injury"). In most contexts, the initial injury is usually mechanical. The more destructive phase of secondary injury is, however, more responsible for cell death and functional deficits. This subject is described and reviewed differently in the literature. To biomedical researchers, systemic and tissue-level changes such as hemorrhage, edema, and ischemia usually define this subject. To cell and molecular biologists, "secondary injury" refers to a series of predominately molecular events and an increasingly restricted set of aberrant biochemical pathways and products. These biochemical and ionic changes are seen to lead to death of the initially compromised cells and "healthy" cells nearby through necrosis or apoptosis. This latter process is called "bystander damage." These viewpoints have largely dominated the recent literature, especially in studies of the central nervous system (CNS), often without attempts to place the molecular events in the context of progressive systemic and tissue-level changes. Here we provide a more comprehensive and inclusive discussion of this topic.

The short-term effects of antioxidant and zinc supplements on oxidative stress biomarker levels in plasma: a pilot investigation

PURPOSE

To determine if short-term Age-Related Eye Disease Study (AREDS) antioxidant and zinc supplementation affects biomarkers of oxidative stress, possibly serving as a predictor of their efficacy.

DESIGN

Prospective interventional case series.

METHODS

Nineteen subjects, 12 with intermediate or advanced age-related macular degeneration (AMD) (AREDS categories 3 or 4) and 7 non-AMD controls, were admitted to the Vanderbilt General Clinical Research Center and placed on a controlled diet for 7 days. Antioxidant and zinc supplements were stopped 2 weeks prior to study enrollment. Dietary supplementation with 500 mg vitamin C, 400 IU vitamin E, 15 mg β-carotene, 80 mg zinc oxide, and 2 mg cupric oxide per day was instituted on study day 2. Blood was drawn on study days 2 and 7, and plasma concentrations of cysteine (Cys), cystine (CySS), glutathione (GSH), isoprostane (IsoP), and isofuran (IsoF) were determined.

RESULTS

Short-term AREDS supplementation significantly lowered mean plasma levels of CySS in participants on a regulated diet (P = .034). No significant differences were observed for Cys, GSH, IsoP, or IsoF. There were no significant differences between AMD patients and controls.

CONCLUSIONS

This pilot interventional study shows that a 5-day course of antioxidant and zinc supplements can modify plasma levels of CySS, suggesting that this oxidative stress biomarker could help predict how likely an individual is to benefit from AREDS supplementation. Further, CySS may be useful for the evaluation of new AMD therapies, particularly those hypothesized to affect redox status.

Plasma biomarkers of oxidative stress and genetic variants in age-related macular degeneration

PURPOSE

To compare plasma levels of oxidative stress biomarkers in patients with age-related macular degeneration (AMD) and controls and to evaluate a potential relationship between biochemical markers of oxidative stress and AMD susceptibility genotypes.

DESIGN

Prospective case-control study.

METHODS

Plasma levels of oxidative stress biomarkers were determined in 77 AMD patients and 75 controls recruited from a clinical practice. Cysteine, cystine (CySS), glutathione, isoprostane, and isofuran were measured, and participants were genotyped for polymorphisms in the complement factor H (CFH) and age-related maculopathy susceptibility 2 (ARMS2) genes.

RESULTS

CySS was elevated in cases compared with controls (P = .013). After adjustment for age, sex, and smoking, this association was not significant. In all participants, CySS levels were associated with the CFH polymorphism rs3753394 (P = .028) as well as an 8-allele CFH haplotype (P = .029) after correction for age, gender, and smoking. None of the other plasma markers was related to AMD status in our cohort.

CONCLUSIONS

Our investigation of the gene-environment interaction involved in AMD revealed a relationship between a plasma biomarker of oxidative stress, CySS, and CFH genotype. These data suggest a potential association between inflammatory regulators and redox status in AMD pathogenesis.

Membrane lipid peroxidation in copper alloy-mediated contact killing of Escherichia coli

Copper alloy surfaces are passive antimicrobial sanitizing agents that kill bacteria, fungi, and some viruses. Studies of the mechanism of contact killing in Escherichia coli implicate the membrane as the target, yet the specific component and underlying biochemistry remain unknown. This study explores the hypothesis that nonenzymatic peroxidation of membrane phospholipids is responsible for copper alloy-mediated surface killing. Lipid peroxidation was monitored with the thiobarbituric acid-reactive substances (TBARS) assay. Survival, TBARS levels, and DNA degradation were followed in cells exposed to copper alloy surfaces containing 60 to 99.90% copper or in medium containing CuSO(4). In all cases, TBARS levels increased with copper exposure levels. Cells exposed to the highest copper content alloys, C11000 and C24000, exhibited novel characteristics. TBARS increased immediately at a very rapid rate but peaked at about 30 min. This peak was associated with the period of most rapid killing, loss in membrane integrity, and DNA degradation. DNA degradation is not the primary cause of copper-mediated surface killing. Cells exposed to the 60% copper alloy for 60 min had fully intact genomic DNA but no viable cells. In a fabR mutant strain with increased levels of unsaturated fatty acids, sensitivity to copper alloy surface-mediated killing increased, TBARS levels peaked earlier, and genomic DNA degradation occurred sooner than in the isogenic parental strain. Taken together, these results suggest that copper alloy surface-mediated killing of E. coli is triggered by nonenzymatic oxidative damage of membrane phospholipids that ultimately results in the loss of membrane integrity and cell death.

The reconstruction and analysis of tissue specific human metabolic networks

Human tissues have distinct biological functions. Many proteins/enzymes are known to be expressed only in specific tissues and therefore the metabolic networks in various tissues are different. Though high quality global human metabolic networks and metabolic networks for certain tissues such as liver have already been studied, a systematic study of tissue specific metabolic networks for all main tissues is still missing. In this work, we reconstruct the tissue specific metabolic networks for 15 main tissues in human based on the previously reconstructed Edinburgh Human Metabolic Network (EHMN). The tissue information is firstly obtained for enzymes from Human Protein Reference Database (HPRD) and UniprotKB databases and transfers to reactions through the enzyme-reaction relationships in EHMN. As our knowledge of tissue distribution of proteins is still very limited, we replenish the tissue information of the metabolic network based on network connectivity analysis and thorough examination of the literature. Finally, about 80% of proteins and reactions in EHMN are determined to be in at least one of the 15 tissues. To validate the quality of the tissue specific network, the brain specific metabolic network is taken as an example for functional module analysis and the results reveal that the function of the brain metabolic network is closely related with its function as the centre of the human nervous system. The tissue specific human metabolic networks are available at .

Docosahexaenoic acid signalolipidomics in nutrition: significance in aging, neuroinflammation, macular degeneration, Alzheimer's, and other neurodegenerative diseases

Essential polyunsaturated fatty acids (PUFAs) are critical nutritional lipids that must be obtained from the diet to sustain homeostasis. Omega-3 and -6 PUFAs are key components of biomembranes and play important roles in cell integrity, development, maintenance, and function. The essential omega-3 fatty acid family member docosahexaenoic acid (DHA) is avidly retained and uniquely concentrated in the nervous system, particularly in photoreceptors and synaptic membranes. DHA plays a key role in vision, neuroprotection, successful aging, memory, and other functions. In addition, DHA displays anti-inflammatory and inflammatory resolving properties in contrast to the proinflammatory actions of several members of the omega-6 PUFAs family. This review discusses DHA signalolipidomics, comprising the cellular/tissue organization of DHA uptake, its distribution among cellular compartments, the organization and function of membrane domains rich in DHA-containing phospholipids, and the cellular and molecular events revealed by the uncovering of signaling pathways regulated by DHA and docosanoids, the DHA-derived bioactive lipids, which include neuroprotectin D1 (NPD1), a novel DHA-derived stereoselective mediator. NPD1 synthesis agonists include neurotrophins and oxidative stress; NPD1 elicits potent anti-inflammatory actions and prohomeostatic bioactivity, is anti-angiogenic, promotes corneal nerve regeneration, and induces cell survival. In the context of DHA signalolipidomics, this review highlights aging and the evolving studies on the significance of DHA in Alzheimer's disease, macular degeneration, Parkinson's disease, and other brain disorders. DHA signalolipidomics in the nervous system offers emerging targets for pharmaceutical intervention and clinical translation.

Endogenous signaling by omega-3 docosahexaenoic acid-derived mediators sustains homeostatic synaptic and circuitry integrity

The harmony and function of the complex brain circuits and synapses are sustained mainly by excitatory and inhibitory neurotransmission, neurotrophins, gene regulation, and factors, many of which are incompletely understood. A common feature of brain circuit components, such as dendrites, synaptic membranes, and other membranes of the nervous system, is that they are richly endowed in docosahexaenoic acid (DHA), the main member of the omega-3 essential fatty acid family. DHA is avidly retained and concentrated in the nervous system and known to play a role in neuroprotection, memory, and vision. Only recently has it become apparent why the surprisingly rapid increases in free (unesterified) DHA pool size take place at the onset of seizures or brain injury. This phenomenon began to be clarified by the discovery of neuroprotectin D1 (NPD1), the first-uncovered bioactive docosanoid formed from free DHA through 15-lipoxygenase-1 (15-LOX-1). NPD1 synthesis includes, as agonists, oxidative stress and neurotrophins. The evolving concept is that DHA-derived docosanoids set in motion endogenous signaling to sustain homeostatic synaptic and circuit integrity. NPD1 is anti-inflammatory, displays inflammatory resolving activities, and induces cell survival, which is in contrast to the pro-inflammatory actions of the many of omega-6 fatty acid family members. We highlight here studies relevant to the ability of DHA to sustain neuronal function and protect synapses and circuits in the context of DHA signalolipidomics. DHA signalolipidomics comprises the integration of the cellular/tissue mechanism of DHA uptake, its distribution among cellular compartments, the organization and function of membrane domains containing DHA phospholipids, and the precise cellular and molecular events revealed by the uncovering of signaling pathways regulated by docosanoids endowed with prohomeostatic and cell survival bioactivity. Therefore, this approach offers emerging targets for prevention, pharmaceutical intervention, and clinical translation involving DHA-mediated signaling.