Blood oxidative stress in amyotrophic lateral sclerosis

Ferroptosis: underlying mechanisms and involvement in neurodegenerative diseases

Ferroptosis, a mode of cell death that was recently identified in 2012, is driven by iron-dependent lipid peroxidation and distinct from other mechanisms of cell death such as autophagy and apoptosis. Ferroptosis has the unique features of disruptions in iron equilibrium, iron-induced lipid peroxidation, and the accumulation of glutamate-induced cellular toxicity. The regulation of ferroptosis mainly involves the iron, lipid, and amino acid metabolic pathways, which are controlled by system Xc-, voltage-dependent anion channels, p53 and other pathways. Neurodegenerative diseases involve gradual neuronal loss predominantly within the central nervous system and are categorized into both sporadic and rare hereditary disorders. These diseases result in the progressive decline of specific neuron populations and their interconnections. Recent investigations have revealed a strong correlation between the manifestation and progression of neurodegenerative diseases and ferroptosis. The pharmacological modulation of ferroptosis, whether by induction or inhibition, exhibits promising prospects for therapeutic interventions for these diseases. This review aims to examine the literature on ferroptosis and its implications in various neurodegenerative diseases. We hope to offer novel insights into the potential therapies targeting ferroptosis in central nervous system neurodegenerative diseases. However, there are still limitations of this review. First, despite our efforts to maintain objectivity during our analysis, this review does not cover all the studies on ferroptosis and neurodegenerative diseases. Second, cell death in neurodegenerative diseases is not solely caused by ferroptosis. Future research should focus on the interplay of different cell death mechanisms to better elucidate the specific disease pathogenesis.

Biochemical and Molecular Pathways in Neurodegenerative Diseases: An Integrated View

Neurodegenerative diseases (NDDs) like Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) are defined by a myriad of complex aetiologies. Understanding the common biochemical molecular pathologies among NDDs gives an opportunity to decipher the overlapping and numerous cross-talk mechanisms of neurodegeneration. Numerous interrelated pathways lead to the progression of neurodegeneration. We present evidence from the past pieces of literature for the most usual global convergent hallmarks like ageing, oxidative stress, excitotoxicity-induced calcium butterfly effect, defective proteostasis including chaperones, autophagy, mitophagy, and proteosome networks, and neuroinflammation. Herein, we applied a holistic approach to identify and represent the shared mechanism across NDDs. Further, we believe that this approach could be helpful in identifying key modulators across NDDs, with a particular focus on AD, PD, and ALS. Moreover, these concepts could be applied to the development and diagnosis of novel strategies for diverse NDDs.

Association of Selenium Levels with Neurodegenerative Disease: A Systemic Review and Meta-Analysis

BACKGROUND

Neurodegenerative diseases (NDs) have posed significant challenges to public health, and it is crucial to understand their mechanisms in order to develop effective therapeutic strategies. Recent studies have highlighted the potential role of selenium in ND pathogenesis, as it plays a vital role in maintaining cellular homeostasis and preventing oxidative damage. However, a comprehensive analysis of the association between selenium and NDs is still lacking.

METHOD

Five public databases, namely PubMed, Web of Science, EMBASE, Cochrane and Clinical Trials, were searched in our research. Random model effects were chosen, and Higgins inconsistency analyses (I2), Cochrane's Q test and Tau2 were calculated to evaluate the heterogeneity.

RESULT

The association of selenium in ND patients with Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD) was studied. A statistically significant relationship was only found for AD patients (SMD = -0.41, 95% CI (-0.64, -0.17), p < 0.001), especially for erythrocytes. However, no significant relationship was observed in the analysis of the other four diseases.

CONCLUSION

Generally, this meta-analysis indicated that AD patients are strongly associated with lower selenium concentrations compared with healthy people, which may provide a clinical reference in the future. However, more studies are urgently needed for further study and treatment of neurodegenerative diseases.

Defects in Glutathione System in an Animal Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progredient neurodegenerative disease characterized by a degeneration of the first and second motor neurons. Elevated levels of reactive oxygen species (ROS) and decreased levels of glutathione, which are important defense mechanisms against ROS, have been reported in the central nervous system (CNS) of ALS patients and animal models. The aim of this study was to determine the cause of decreased glutathione levels in the CNS of the ALS model wobbler mouse. We analyzed changes in glutathione metabolism in the spinal cord, hippocampus, cerebellum, liver, and blood samples of the ALS model, wobbler mouse, using qPCR, Western Blot, HPLC, and fluorometric assays. Here, we show for the first time a decreased expression of enzymes involved in glutathione synthesis in the cervical spinal cord of wobbler mice. We provide evidence for a deficient glutathione metabolism, which is not restricted to the nervous system, but can be seen in various tissues of the wobbler mouse. This deficient system is most likely the reason for an inefficient antioxidative system and, thus, for elevated ROS levels.

Role and Mechanism of Ferroptosis in Neurological Diseases

Background

Ferroptosis, as a new form of cell death, is different from other cell deaths such as autophagy or senescence. Ferroptosis involves in the pathophysiological progress of several diseases, including cancers, cardiovascular diseases, nervous system diseases, and kidney damage. Since oxidative stress and iron deposition are the broad pathological features of neurological diseases, the role of ferroptosis in neurological diseases has been widely explored.

Scope of review

Ferroptosis is mainly characterized by changes in iron homeostasis, iron-dependent lipid peroxidation, and glutamate toxicity accumulation, of which can be specifically reversed by ferroptosis inducers or inhibitors. The ferroptosis is mainly regulated by the metabolism of iron, lipids and amino acids through System Xc⁻, voltage-dependent anion channels, p53, p62-Keap1-Nrf2, mevalonate and other pathways. This review also focus on the regulatory pathways of ferroptosis and its research progress in neurological diseases.

Major conclusions

The current researches of ferroptosis in neurological diseases mostly focus on the key pathways of ferroptosis. At the same time, ferroptosis was found playing a bidirectional regulation role in neurological diseases. Therefore, the specific regulatory mechanisms of ferroptosis in neurological diseases still need to be further explored to provide new perspectives for the application of ferroptosis in the treatment of neurological diseases.

A photoelectrochemical sensor for glutathione based on Bi2S3-modified TiO2 nanotube arrays

A novel photoelectrochemical sensor for the determination of glutathione based on Bi2S3-modified TiO2 nanotube arrays. Under the excitation of visible light, glutathione can be oxidized by the holes created by the Bi2S3/TiO2 NTAs.

Biomolecular Modifications Linked to Oxidative Stress in Amyotrophic Lateral Sclerosis: Determining Promising Biomarkers Related to Oxidative Stress

Reduction–oxidation reactions are essential to cellular homeostasis. Oxidative stress transcends physiological antioxidative system damage to biomolecules, including nucleic acids and proteins, and modifies their structures. Amyotrophic lateral sclerosis (ALS) is the most common adult-onset motor neuron disease. The cells present in the central nervous system, including motor neurons, are vulnerable to oxidative stress. Neurodegeneration has been demonstrated to be caused by oxidative biomolecular modifications. Oxidative stress has been suggested to be involved in the pathogenesis of ALS. Recent progress in research on the underlying mechanisms of oxidative stress in ALS has led to the development of disease-modifying therapies, including edaravone. However, the clinical effects of edaravone remain limited, and ALS is a heretofore incurable disease. The reason for the lack of reliable biomarkers and the precise underlying mechanisms between oxidative stress and ALS remain unclear. As extracellular proteins and RNAs present in body fluids and represent intracellular pathological neurodegenerative processes, extracellular proteins and/or RNAs are predicted to promise diagnosis, prediction of disease course, and therapeutic biomarkers for ALS. Therefore, we aimed to elucidate the underlying mechanisms between oxidative stress and ALS, and promising biomarkers indicating the mechanism to determine whether therapy targeting oxidative stress can be fundamental for ALS.

NRF2 as a therapeutic opportunity to impact in the molecular roadmap of ALS

Amyotrophic Lateral Sclerosis (ALS) is a devastating heterogeneous disease with still no convincing therapy. To identify the most strategically significant hallmarks for therapeutic intervention, we have performed a comprehensive transcriptomics analysis of dysregulated pathways, comparing datasets from ALS patients and healthy donors. We have identified crucial alterations in RNA metabolism, intracellular transport, vascular system, redox homeostasis, proteostasis and inflammatory responses. Interestingly, the transcription factor NRF2 (nuclear factor (erythroid-derived 2)-like 2) has significant effects in modulating these pathways. NRF2 has been classically considered as the master regulator of the antioxidant cellular response, although it is currently considered as a key component of the transduction machinery to maintain coordinated control of protein quality, inflammation, and redox homeostasis. Herein, we will summarize the data from NRF2 activators in ALS pre-clinical models as well as those that are being studied in clinical trials. As we will discuss, NRF2 is a promising target to build a coordinated transcriptional response to motor neuron injury, highlighting its therapeutic potential to combat ALS.

Effects of vitamin E on neurodegenerative diseases: an update

Vitamin E deficiency is associated with many neurological problems. Although the mechanisms of vitamin E action in neurodegenerative diseases are not clear, there are many possible mechanisms. Examples of such mechanisms are the protective effects of vitamin E against oxidative stress damage and its suppressive role in the expression of many genes involved in the development of neurodegeneration. Many studies have evaluated the relationship between vitamin E intake or vitamin E levels in body fluids and neurodegenerative diseases. Some studies concluded that vitamin E can play a protective role in neurodegeneration with respect to diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), stroke and amyotrophic lateral sclerosis (ALS). Vitamin E supplementation was also associated with risk factors for some neurodegenerative diseases. In this review, we discuss the possible effects of vitamin E on the development and course of AD, PD, stroke and ALS, and the potential mechanisms involved.

Vitamin E deficiency is associated with many neurological problems. Although the mechanisms of vitamin E action in neurodegenerative diseases are not clear, there are many possible mechanisms. Examples of such mechanisms are the protective effects of vitamin E against oxidative stress damage and its suppressive role in the expression of many genes involved in the development of neurodegeneration. Many studies have evaluated the relationship between vitamin E intake or vitamin E levels in body fluids and neurodegenerative diseases. Some studies concluded that vitamin E can play a protective role in neurodegeneration with respect to diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), stroke and amyotrophic lateral sclerosis (ALS). Vitamin E supplementation was also associated with risk factors for some neurodegenerative diseases. In this review, we discuss the possible effects of vitamin E on the development and course of AD, PD, stroke and ALS, and the potential mechanisms involved.

Decreased Mitochondrial Function, Biogenesis, and Degradation in Peripheral Blood Mononuclear Cells from Amyotrophic Lateral Sclerosis Patients as a Potential Tool for Biomarker Research

Amyotrophic lateral sclerosis (ALS) is a multifactorial and progressive neurodegenerative disease of unknown etiology. Due to ALS’s unpredictable onset and progression rate, the search for biomarkers that allow the detection and tracking of its development and therapeutic efficacy would be of significant medical value. Considering that alterations of energy supply are one of ALS’s main hallmarks and that a correlation has been established between gene expression in human brain tissue and peripheral blood mononuclear cells (PBMCs), the present work investigates whether changes in mitochondrial function could be used to monitor ALS. To achieve this goal, PBMCs from ALS patients and control subjects were used; blood sampling is a quite non-invasive method and is cost-effective. Different parameters were evaluated, namely cytosolic calcium levels, mitochondrial membrane potential, oxidative stress, and metabolic compounds levels, as well as mitochondrial dynamics and degradation. Altogether, we observed lower mitochondrial calcium uptake/retention, mitochondria depolarization, and redox homeostasis deregulation, in addition to a decrease in critical metabolic genes, a diminishment in mitochondrial biogenesis, and an augmentation in mitochondrial fission and autophagy-related gene expression. All of these changes can contribute to the decreased ATP and pyruvate levels observed in ALS PBMCs. Our data indicate that PBMCs from ALS patients show a significant mitochondrial dysfunction, resembling several findings from ALS’ neural cells/models, which could be exploited as a powerful tool in ALS research. Our findings can also guide future studies on new pharmacological interventions for ALS since assessments of brain samples are challenging and represent a relevant limited strategy.

Aberrations in Oxidative Stress Markers in Amyotrophic Lateral Sclerosis: A Systematic Review and Meta-Analysis

Oxidative stress has been reported to be involved in the onset and development of amyotrophic lateral sclerosis (ALS). Data from clinical studies have highlighted increased peripheral blood oxidative stress markers in patients with ALS, but results are inconsistent. Therefore, we quantitatively pooled data on levels of blood oxidative stress markers in ALS patients from the literature using a meta-analytic technique. A systematic search was performed on PubMed and Web of Science, and we included studies analyzing blood oxidative stress marker levels in patients with ALS and normal controls. We included 41 studies with 4,588 ALS patients and 6,344 control subjects, and 15 oxidative stress marker levels were subjected to random-effects meta-analysis. The results demonstrated that malondialdehyde (Hedges' g, 1.168; 95% CI, 0.812 to 1.523; P < 0.001), 8-hydroxyguanosine (Hedges' g, 2.194; 95% CI, 0.554 to 3.835; P = 0.009), and Advanced Oxidation Protein Product (Hedges' g, 0.555; 95% CI, 0.317 to 0.792; P < 0.001) levels were significantly increased in patients with ALS when compared with control subjects. Uric acid (Hedges' g, -0.798; 95% CI, -1.117 to -0.479; P < 0.001) and glutathione (Hedges' g, -1.636; 95% CI, -3.020 to -0.252; P = 0.02) levels were significantly reduced in ALS patients. In contrast, blood Cu, superoxide dismutase, glutathione peroxidase, ceruloplasmin, triglycerides, total cholesterol, low-density lipoprotein, high-density lipoprotein, coenzyme-Q10, and transferrin levels were not significantly different between cases and controls. Taken together, our results showed significantly increased blood levels of 8-hydroxyguanosine, malondialdehyde, and Advanced Oxidation Protein Product and decreased glutathione and uric acid levels in the peripheral blood of ALS patients. This meta-analysis helps to clarify the oxidative stress marker profile in ALS patients, supporting the hypothesis that oxidative stress is a central component underpinning ALS pathogenesis.

Ferroptosis and Its Role in Diverse Brain Diseases

Ferroptosis is a recently identified, iron-regulated, non-apoptotic form of cell death. It is characterized by cellular accumulation of lipid reactive oxygen species that ultimately leads to oxidative stress and cell death. Although first identified in cancer cells, ferroptosis has been shown to have significant implications in several neurologic diseases, such as ischemic and hemorrhagic stroke, Alzheimer's disease, and Parkinson's disease. This review summarizes current research on ferroptosis, its underlying mechanisms, and its role in the progression of different neurologic diseases. Understanding the role of ferroptosis could provide valuable information regarding treatment and prevention of these devastating diseases.

Comparing Palm Oil, Tocotrienol-Rich Fraction and α-Tocopherol Supplementation on the Antioxidant Levels of Older Adults

BACKGROUND

Tocotrienol and tocopherol are known to prevent numerous degenerative diseases. The aim of this study is to compare the effects of tocotrienol-rich fraction (TRF) with α-tocopherol (α-TF) on the antioxidant status of healthy individuals aged between 50 and 55 years.

METHODS

Volunteers were divided into groups receiving placebo (n = 23), α-TF (n = 24) and TRF (n = 24). Fasting venous blood samples were taken at baseline (0 month), 3 months and 6 months of supplementation for the determination of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities as well as for reduced glutathione (GSH) and oxidized glutathione (GSSG) concentrations.

RESULTS

CAT and GPx were unaffected by TRF and α-TF supplementations. SOD activity increased significantly after six months of TRF supplementation. Analysis by gender showed that only female subjects had significant increases in SOD and GPx activities after six months of TRF supplementation. GPx activity was also significantly higher in females compared to males after six months of TRF supplementation. The GSH/GSSG ratio increased significantly after six months of TRF and α-TF supplementation in only the female subjects.

CONCLUSION

TRF and α-TF supplementation exhibited similar effects to the antioxidant levels of older adults with TRF having more significant effects in females.

The discovery and development of new potential antioxidant agents for the treatment of neurodegenerative diseases

INTRODUCTION

Several neurodegenerative disorders (NDs) including Alzheimer's and Huntington's diseases have had associations with the oxidative process and free radical damage. Consequently, in past decades, several natural and synthetic antioxidants have been assessed as therapeutic agents but have shown limitations in bioavailability, metabolic susceptibility and permeability to the blood brain barrier. Given these issues, medicinal chemists are hard at work to modify/improve the chemical structures of these antioxidants, thereby improving their efficacy.

AREAS COVERED

In this review, the authors critically analyze several biological mechanisms involved in the generation of free radicals. Additionally, they analyze free radicals' role in the generation of oxidative stress and in the progression of many NDs. Further, the authors review a collection of natural and synthetic antioxidants, their role as free radical scavengers along with their mechanisms of action and their potential for preventing neurodegenerative diseases.

EXPERT OPINION

So far, preclinical studies on several antioxidants have shown promise for treating NDs, despite their limitations. The authors do highlight the lack of the adequate animal models for preclinical assessment and this does hinder further progression into clinical trials. Further studies are necessary to fully investigate the potential of these antioxidants as ND therapeutic options.

Catalase activity in blood fractions of patients with sporadic ALS

BACKGROUND

Oxidative stress may be a key element in pathogenesis of sporadic amyotrophic lateral sclerosis (sALS). Several studies proved that markers of peroxidation of lipids, proteins or nucleic acids are increased in postmortem tissue of sALS patients. However, much less is known about enzymatic antioxidant defense mechanism in sALS.

OBJECTIVES

The aim of the study was to assess catalase (CAT) activity that is implicated in the defense against oxidative stress, in three blood fractions, i.e. erythrocytes, plasma and serum of sALS patients and healthy controls.

METHODS

Altogether 46 sALS patients and 54 controls were enrolled in the study. CAT activity was estimated using a commercially available assay kit.

RESULTS

CAT activity in erythrocytes of sALS patients was significantly decreased compared to neurologically healthy controls (p=0.04), whereas CAT activity in plasma and serum was similar in both studied groups.

CONCLUSIONS

CAT activity in erythrocytes, in contrast to other blood fractions is reduced in sALS cases as compared to controls, which may indirectly indicate that antioxidant defense system in erythrocytes is involved in pathogenesis of sALS.

Motor cortex glutathione deficit in ALS measured in vivo with the J-editing technique

This study compared in vivo levels of the antioxidant glutathione (GSH) in the motor cortex of 11 ALS patients with those in 11 age-matched healthy volunteers (HV). Using the standard J-edited spin-echo difference MRS technique, GSH spectra were recorded on a 3.0 T GE MR system from a single precentral gyrus voxel. GSH levels expressed as ratios to the unsuppressed voxel tissue water (W) were 31% lower in ALS patients than in HV (p=.005), and 36% lower in ALS than in HV (p=.02) when expressed as ratios to the total creatine peak (tCr), supporting a role for oxidative stress in ALS. Levels of the putative neuronal marker N-acetylaspartate (NAA) relative to W did not differ between ALS and HV (p=.26), but were lower by 9% in ALS than in HV (p=.013) when expressed as ratios relative to tCr. This discrepancy is attributed to small but opposite changes in NAA and tCr in ALS that, as a ratio, resulted in a statistically significant group difference, further suggesting caution in using tCr as an internal reference under pathological conditions.

Clinical perspective on oxidative stress in sporadic amyotrophic lateral sclerosis

Sporadic amyotrophic lateral sclerosis (ALS) is one of the most devastating neurological diseases; most patients die within 3 to 4 years after symptom onset. Oxidative stress is a disturbance in the pro-oxidative/antioxidative balance favoring the pro-oxidative state. Autopsy and laboratory studies in ALS indicate that oxidative stress plays a major role in motor neuron degeneration and astrocyte dysfunction. Oxidative stress biomarkers in cerebrospinal fluid, plasma, and urine are elevated, suggesting that abnormal oxidative stress is generated outside of the central nervous system. Our review indicates that agricultural chemicals, heavy metals, military service, professional sports, excessive physical exertion, chronic head trauma, and certain foods might be modestly associated with ALS risk, with a stronger association between risk and smoking. At the cellular level, these factors are all involved in generating oxidative stress. Experimental studies indicate that a combination of insults that induce modest oxidative stress can exert additive deleterious effects on motor neurons, suggesting that multiple exposures in real-world environments are important. As the disease progresses, nutritional deficiency, cachexia, psychological stress, and impending respiratory failure may further increase oxidative stress. Moreover, accumulating evidence suggests that ALS is possibly a systemic disease. Laboratory, pathologic, and epidemiologic evidence clearly supports the hypothesis that oxidative stress is central in the pathogenic process, particularly in genetically susceptive individuals. If we are to improve ALS treatment, well-designed biochemical and genetic epidemiological studies, combined with a multidisciplinary research approach, are needed and will provide knowledge crucial to our understanding of ALS etiology, pathophysiology, and prognosis.

Dietary intake of fruits and beta-carotene is negatively associated with amyotrophic lateral sclerosis risk in Koreans: a case-control study

OBJECTIVES

Amyotrophic lateral sclerosis (ALS), a rare progressive neurodegenerative disease, has been suggested to have an association with oxidative stress, and thus antioxidant dietary factors may influence pathophysiological mechanisms or the risk of ALS. The purpose of the present study was to investigate the hypothesis that intake of fruits, rich in antioxidant nutrients, is negatively associated with the risk of ALS.

METHODS

Seventy-seven Koreans diagnosed with ALS according to the EI Escorial criteria-revised and the same number of age- and sex-matched healthy controls participated in this study. Dietary intake was estimated using the standardized food frequency questionnaire.

RESULTS

Multivariate logistic regression analysis showed that fruit consumption was negatively associated with the risk of ALS, but intake of beef, fish, and fast food were positively associated with the risk of ALS. In addition, the risk of ALS was negatively associated with intake of plant calcium and beta-carotene, while positively associated with intake of total calcium and animal calcium. Intake of vegetables and other antioxidant nutrients had no effect on the risk of ALS in the present study.

DISCUSSION

The intake of fruits and beta-carotene decreases the risk of sporadic ALS in this present study. However, large prospective and interventional studies are needed to confirm the effect of fruits and beta-carotene intake on the risk of ALS.

Adaptive and maladaptive motor axonal sprouting in aging and motoneuron disease

Motor unit (MU) enlargement by sprouting is an important compensatory mechanism for loss of functional MUs during normal aging and neuromuscular disease. Perisynaptic Schwann cells at neuromuscular junctions extend processes that bridge between denervated and reinnervated endplates, and guide axonal sprouts to reinnervate the denervated endplates. In a rat model of partial denervation, high levels of daily neuromuscular activity have been shown to inhibit the outgrowth of sprouts by preventing Schwann cell bridging. In this review, we consider (1) the relative roles of increasing levels of oxidative stress and neuromuscular activity to the destabilization of neuromuscular junctions with age and disease, and (2) how a progressive increase in the neuromuscular activity of declining numbers of functional MUs contributes to the progressive failure of adaptive sprouting and, in turn, to the progressive muscle weakness in the motoneuron diseases of post-polio syndrome and amyotrophic lateral sclerosis. We conclude that there is a time-related progression of MU loss, adaptive sprouting followed by maladaptive sprouting, and continuing recession of terminals during normal aging. The progression is accelerated in motoneuron disease, progressing more rapidly in the post-polio syndrome after prolonged denervation and extremely rapidly in ALS.

Riluzole increases glutamate uptake by cultured C6 astroglial cells

Riluzole is a drug approved for the treatment of amyotrophic lateral sclerosis (ALS) and may be effective for the treatment of other neurodegenerative and neuropsychiatric disorders. Riluzole exerts diverse actions on the central nervous system, including altering glutamate release and uptake, and therefore act diminishing glutamate extracellular levels, but the underlying mechanism of these actions is still unknown. Here, we demonstrate that riluzole stimulated glutamate uptake and augmented the expression of the glutamate EAAC1 transporter in C6 astroglial cell cultures. The effect of riluzole on glutamate uptake was reduced to below controls when it was co-administered with inhibitors of protein kinase C (PKC; bisindolylmaleimide II), phosphatidylinositol 3-kinase (PI3K; wortmannin) and fibroblast growth factor receptor 1 (FGFR1; PD173074). Riluzole also decreased reactive oxygen species load with no effect on glutathione levels. This study investigates three independent intracellular pathways and the mechanism of action of riluzole on glutamate metabolism.

Markers of oxidant stress that are clinically relevant in aging and age-related disease

Despite the long held hypothesis that oxidant stress results in accumulated oxidative damage to cellular macromolecules and subsequently to aging and age-related chronic disease, it has been difficult to consistently define and specifically identify markers of oxidant stress that are consistently and directly linked to age and disease status. Inflammation because it is also linked to oxidant stress, aging, and chronic disease also plays an important role in understanding the clinical implications of oxidant stress and relevant markers. Much attention has focused on identifying specific markers of oxidative stress and inflammation that could be measured in easily accessible tissues and fluids (lymphocytes, plasma, serum). The purpose of this review is to discuss markers of oxidant stress used in the field as biomarkers of aging and age-related diseases, highlighting differences observed by race when data is available. We highlight DNA, RNA, protein, and lipid oxidation as measures of oxidative stress, as well as other well-characterized markers of oxidative damage and inflammation and discuss their strengths and limitations. We present the current state of the literature reporting use of these markers in studies of human cohorts in relation to age and age-related disease and also with a special emphasis on differences observed by race when relevant.

Intakes of vitamin C and carotenoids and risk of amyotrophic lateral sclerosis: pooled results from 5 cohort studies

OBJECTIVE

Prior research has suggested the possible role of oxidative stress in the pathogenesis of amyotrophic lateral sclerosis (ALS). Prospective data examining dietary antioxidants such carotenoids and vitamin C are limited.

METHODS

Risk of ALS associated with carotenoid and vitamin C intake was investigated in 5 prospective cohorts: the National Institutes of Health-Association of American Retired Persons Diet and Health Study, the Cancer Prevention Study II Nutrition Cohort, the Multiethnic Cohort, the Health Professionals Follow-up Study (HPFS), and the Nurses Health Study (NHS). ALS deaths were documented using the National Death Index, and confirmed nonfatal ALS cases were included from HPFS and NHS. A total of 1,153 ALS deaths occurred among 1,100,910 participants (562,942 men; 537,968 women). Participants were categorized into cohort-specific quintiles of intake for dietary variables. We applied Cox proportional hazards regression to calculate cohort-specific risk ratios (RRs), and pooled results using random-effects methods.

RESULTS

A greater total major carotenoids intake was associated with a reduced risk of ALS (pooled, multivariate-adjusted RR for the highest to the lowest quintile = 0.75, 95% confidence interval [CI] = 0.61-0.91, p for trend = 0.004). Individually, higher dietary intakes of β-carotene and lutein were inversely associated with ALS risk. The pooled multivariate RRs comparing the highest to the lowest quintile for β-carotene and lutein were 0.85 (95% CI = 0.64-1.13, p for trend = 0.03) and 0.79 (95% CI = 0.64-0.96, p for trend = 0.01), respectively. Lycopene, β-cryptoxanthin, and vitamin C were not associated with reduced risk of ALS.

INTERPRETATION

Consumption of foods high in carotenoids may help prevent or delay onset of ALS.

Vitamin E serum levels and controlled supplementation and risk of amyotrophic lateral sclerosis

There are no observational studies or controlled trials of amyotrophic lateral sclerosis (ALS) and circulating α-tocopherol (vitamin E) for prevention of ALS. This study addresses that gap. The study population comprised 29,127 Finnish male smokers, aged 50-69 years, who participated in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, which is both a prospective cohort and a randomized, double-blind, placebo-controlled trial of α-tocopherol (50 mg/day) and β-carotene (20 mg/day). Serum α-tocopherol and β-carotene was assayed at baseline (1985 - 1988). Follow-up (median 16.7 years) continued through 2004. ALS cases were identified through the national Hospital Discharge Register with diagnostic verification by hospital records and death certificates. During 407,260 person-years of follow-up, 50 men were identified with ALS. For males with serum α-tocopherol concentration above the median (≥ 11.6 mg/l), the age-adjusted relative risk (RR) compared to α-tocopherol below the median, was 0.56 (95% confidence interval 0.32 - 0.99), p = 0.046. The RR among α-tocopherol supplement recipients was 0.75 (95% CI 0.32 - 1.79), p = 0.52. Neither serum β-carotene level nor β-carotene supplementation was associated with ALS. In conclusion, the results are consistent with a hypothesized protective effect of α-tocopherol on ALS risk. However, pooled analyses of cohorts with serum and controlled trials are needed to clarify the role of α-tocopherol in ALS risk.

Morphological abnormalities in mitochondria of the skin of patients with sporadic amyotrophic lateral sclerosis

OBJECTIVES

Mitochondrial dysfunction has been reported in the central nervous system, hepatocytes and peripheral blood lymphocytes from patients with sporadic amyotrophic lateral sclerosis (SALS). However, the status of skin mitochondria has not been reported, in spite of the fact that SALS patients present skin abnormalities. The objective of the present study was to compare mitochondrial ultrastructural parameters in keratinocytes from patients with SALS and healthy controls.

METHODS

Our study was based on the analysis of 112 skin mitochondria from 5 SALS patients and 99 organelles from 4 control subjects by electron microscopy.

RESULTS

Computerized image analysis showed that mitochondrial major axis length, area and perimeter of the organelle were significantly smaller in SALS respect of healthy control subjects. Morphologically, SALS mitochondria presented cristolysis and breakage of the outer membrane.

CONCLUSIONS

Mitochondrial dysfunction in the skin may possibly reflect changes occurring in mitochondria of the central nervous system. The analysis of mitochondrial morphology in this tissue may be of value to follow disease progression and, eventually, the effectiveness of current therapies for SALS.

Dysregulation of glutathione homeostasis in neurodegenerative diseases

Dysregulation of glutathione homeostasis and alterations in glutathione-dependent enzyme activities are increasingly implicated in the induction and progression of neurodegenerative diseases, including Alzheimer’s, Parkinson’s and Huntington’s diseases, amyotrophic lateral sclerosis, and Friedreich’s ataxia. In this review background is provided on the steady-state synthesis, regulation, and transport of glutathione, with primary focus on the brain. A brief overview is presented on the distinct but vital roles of glutathione in cellular maintenance and survival, and on the functions of key glutathione-dependent enzymes. Major contributors to initiation and progression of neurodegenerative diseases are considered, including oxidative stress, protein misfolding, and protein aggregation. In each case examples of key regulatory mechanisms are identified that are sensitive to changes in glutathione redox status and/or in the activities of glutathione-dependent enzymes. Mechanisms of dysregulation of glutathione and/or glutathione-dependent enzymes are discussed that are implicated in pathogenesis of each neurodegenerative disease. Limitations in information or interpretation are identified, and possible avenues for further research are described with an aim to elucidating novel targets for therapeutic interventions. The pros and cons of administration of N-acetylcysteine or glutathione as therapeutic agents for neurodegenerative diseases, as well as the potential utility of serum glutathione as a biomarker, are critically evaluated.

Photoelectrocatalytic oxidation of glutathione based on porous TiO2-Pt nanowhiskers

The performance of TiO(2) nanoparticles is extremely attractive in various areas of chemical and biochemical engineering as they can effectively work by combining the photocatalytic property with various superior properties of the related nanostructure. The relevant photoelectrochemical detection has attracted considerable interest and shown potential applications in a wide range of areas. In this study, we have prepared new nanowhiskers of platinum-doped titanium dioxide (TiO(2)-Pt), which could be further used to fabricate a novel nanointerface for the sensitive detection of biomolecules including glutathione (GSH). Our observations demonstrate that the sensitive TiO(2)-Pt nanowhiskers biointerface could be readily fabricated by casting the TiO(2)-Pt nanowhiskers suspension on a glassy carbon electrode (GCE), which could readily combine the photocatalytic and eletrocatalytic properties of TiO(2) nanocomposites to introduce a novel photoelectrocatalytic biosensor for GSH detection in real samples. Compared to other analysis strategies, the TiO(2)-Pt nanowhiskers-modified GCE showed a considerably high sensitivity for the detection of GSH due to the excellent photoelectrocatalytic ability of the porous TiO(2)-Pt nanowhiskers. Scanning electron microscopy (SEM), Raman spectroscopy, and electrochemical impedance spectroscopy have shown that Pt can readily blend with porous TiO(2) nanowhiskers and facilitate the relevant catalysis property of TiO(2), resulting in the enhanced photoelectrocatalytic effect. Thus, through the new strategy of the utilization of the excellent photoelectrocatalytic property of TiO(2)-Pt nanocomposites, it is possible to realize the rapid electrochemical detection of glutathione with high sensitivity, low cost, and good reproducibility.

Progesterone and cortisol levels in sporadic amyotrophic lateral sclerosis (sALS): correlation with prognostic factors

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder. Worse prognostic factors in ALS are: (a) advanced age, (b) bulbar onset, and (c) short time between onset and diagnosis. Progesterone (PROG) has been associated with neuroprotective and promyelinating activities in injury, ischemia and degeneration of the central and peripheral nervous system. Cortisol is connected to the response to stress situations and could contribute to neuronal damage. The goals of this study were: (i) to investigate whether PROG levels are modified by ALS prognostic factors and (ii) to determine whether cortisol follows the same pattern. We determined serum steroid levels in 27 patients with sporadic ALS (sALS) and 21 controls. Both steroid hormones showed significantly increased levels in ALS patients versus controls (mean±SEM: PROG ALS vs.

CONTROL

0.54±0.05 vs. 0.39±0.04 ng/mL, p<0.05; cortisol ALS vs.

CONTROL

17.02±1.60 vs. 11.83±1.38 μg/dL, p<0.05).1 A trend towards higher levels of PROG were demonstrated in spinal onset patients compared with bulbar onset (p=0.07), positive correlation with survival time (RRho=0.43, p=0.04) and a trend towards significance with time to diagnosis (RRho=0.36, p=0.06). These correlations have not been demonstrated for cortisol. Elevated serum steroid levels in sALS were probably due to hyperfunction of the hypothalamic-pituitary-adrenal axis. However, only PROG correlated with better prognostic factors. Future studies will determine if the different behavior of PROG and cortisol relate to any particular role they might play during the course of this motor neuron degenerative disease.

Vitamin E intake and risk of amyotrophic lateral sclerosis: a pooled analysis of data from 5 prospective cohort studies

The authors investigated whether vitamin E intake was associated with amyotrophic lateral sclerosis (ALS) in the Nurses' Health Study (1976-2004), the Health Professionals Follow-up Study (1986-2004), the Cancer Prevention Study II Nutrition Cohort (1992-2004), the Multiethnic Cohort Study (1993-2005), and the National Institutes of Health-AARP Diet and Health Study (1995-2005). ALS deaths were identified through the National Death Index. In the Nurses' Health Study and the Health Professionals Follow-up Study, confirmed nonfatal ALS cases were also included. Cohort-specific results were estimated using Cox proportional hazards models and pooled using random-effects models. Among 1,055,546 participants, 805 developed ALS. Overall, using vitamin E supplements was not associated with ALS. However, within cohorts with information on duration of vitamin E supplement use (231 cases), ALS rates declined with increasing years of use (P-trend=0.01). Compared with nonusers, the multivariable-adjusted relative risk was 1.05 (95% confidence interval (CI): 0.60, 1.84) among users for ≤1 year (12 cases), 0.77 (95% CI: 0.33, 1.77) among users for 2-4 years (7 cases), and 0.64 (95% CI: 0.39, 1.04) among users for ≥5 years (18 cases). For dietary vitamin E intake, the multivariable-adjusted relative risk comparing the highest quartile with the lowest was 0.79 (95% CI: 0.61, 1.03); an inverse dose-response was evident in women (P-trend=0.002) but not in men (P-trend=0.71). In this large, pooled prospective study, long-term vitamin E supplement use was associated with lower ALS rates. A possible protective effect of vitamin E deserves further consideration.

The role of oxidative stress in amyotrophic lateral sclerosis and Parkinson's disease

We examined oxidative stress markers of 31 patients suffering from ALS, 24 patients suffering from PD and 30 healthy subjects were included. We determined the plasma levels of lipid peroxidation (malondialdehyde, MDA), of protein oxidative lesions (plasma glutathione, carbonyls and thiols) and the activity of antioxidant enzymes i.e. erythrocyte Cu,Zn-Superoxide dismutase (SOD), Glutathione peroxidase (GSH-Px) and catalase. MDA and thiols were significantly different in both neurodegenerative diseases versus control population. A trend for an enhancement of oxidized glutathione was noted in ALS patients. Univariate analysis showed that SOD activity was significantly decreased in ALS and GSH-Px activity was decreased in PD. After adjusting for demographic parameters and enzyme cofactors, we could emphasize a compensatory increase of SOD activity in PD. Different antioxidant systems were not involved in the same way in ALS and PD, suggesting that oxidative stress may be a cause rather than a consequence of the neuronal death.

Experimental models for the study of neurodegeneration in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of unknown cause, characterized by the selective and progressive death of both upper and lower motoneurons, leading to a progressive paralysis. Experimental animal models of the disease may provide knowledge of the pathophysiological mechanisms and allow the design and testing of therapeutic strategies, provided that they mimic as close as possible the symptoms and temporal progression of the human disease. The principal hypotheses proposed to explain the mechanisms of motoneuron degeneration have been studied mostly in models in vitro, such as primary cultures of fetal motoneurons, organotypic cultures of spinal cord sections from postnatal rodents and the motoneuron-like hybridoma cell line NSC-34. However, these models are flawed in the sense that they do not allow a direct correlation between motoneuron death and its physical consequences like paralysis. In vivo, the most widely used model is the transgenic mouse that bears a human mutant superoxide dismutase 1, the only known cause of ALS. The major disadvantage of this model is that it represents about 2%-3% of human ALS. In addition, there is a growing concern on the accuracy of these transgenic models and the extrapolations of the findings made in these animals to the clinics. Models of spontaneous motoneuron disease, like the wobbler and pmn mice, have been used aiming to understand the basic cellular mechanisms of motoneuron diseases, but these abnormalities are probably different from those occurring in ALS. Therefore, the design and testing of in vivo models of sporadic ALS, which accounts for >90% of the disease, is necessary. The main models of this type are based on the excitotoxic death of spinal motoneurons and might be useful even when there is no definitive demonstration that excitotoxicity is a cause of human ALS. Despite their difficulties, these models offer the best possibility to establish valid correlations between cellular alterations and motor behavior, although improvements are still necessary in order to produce a reliable and integrative model that accurately reproduces the cellular mechanisms of motoneuron degeneration in ALS.

Linking neuron and skin: matrix metalloproteinases in amyotrophic lateral sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) mainly affects the motor neurons but may also include other organs such as the skin. We aimed to determine whether matrix metalloproteinases could provide a link between neuronal degeneration and skin alterations in ALS. We measured CSF, serum and skin tissue MMP-2 and MMP-9 using ELISA and malondialdehyde (MDA), a marker of lipid peroxidation, using High Performance Liquid Chromatography (HPLC) in 54 ALS patients and 36 controls. We found CSF and skin MMP-9 to be elevated in ALS as compared to controls (p<0.001, p=0.03, respectively). We observed CSF MMP-9 to be highest in patients with a rapid progressive course of disease (p=0.008). In contrast, we found no significant differences of CSF, serum or skin concentrations of MMP-2 as compared to controls. CSF MMP-2 concentrations decreased with duration of disease (p=0.04, R=-0.31). MDA was elevated in serum of ALS (p<0.001), though no correlation with MMP-2 or MMP-9 was observed. Our findings indicate a general upregulation of MMP-9 in ALS. MMP-9 seems to play a role in both neurodegeneration and skin changes in ALS and could thus be a common factor linking otherwise distant aspects of disease pathology.

Nutrition and dietary supplements in motor neuron disease

Compromised nutrition leading to weight loss is a common and significant problem in the amyotrophic lateral sclerosis (ALS) patient population. The benefit of aggressive and early nutritional therapy can profoundly influence the disease course, quality of life, and survival. This article reviews the role of nutrition, both as sustenance and treatment for patients who have ALS. Self-medication with dietary supplements has become increasingly popular within this patient population. Despite their popularity, the efficacy of these compounds has been largely unsupported by formal clinical trials. Available data will be highlighted to provide a basis upon which to advise patients requesting guidance.

Increased serum ferritin levels in amyotrophic lateral sclerosis (ALS) patients

Iron misregulation promotes oxidative stress, a proposed pathological mechanism in neurodegenerative disease. The aim of this study was to evaluate serum iron metabolism indicators in 60 amyotrophic lateral sclerosis (ALS) patients and 44 age matched controls. Serum ferritin levels were significantly increased in ALS patients compared to controls (p < 0.001), while no differences in the levels of serum iron, transferrin, iron saturation or total iron binding capacity were found. Likewise no differences in C reactive protein (CRP) or caeruloplasmin were detected, suggesting that the elevated ferritin levels in ALS did not merely indicate an acute phase response. The increased ferritin level may reflect a general increase in stored iron or be a consequence of ongoing muscle degeneration.

Increased mitochondrial oxidative damage and oxidative DNA damage contributes to the neurodegenerative process in sporadic amyotrophic lateral sclerosis

To investigate the possibility that mitochondrial oxidative damage or oxidative DNA damage or both contribute to the neurodegenerative process of sporadic amyotrophic lateral sclerosis (sALS), this study used high-performance liquid chromatography with an electrochemical detector to measure the concentrations of the reduced and oxidized forms of coenzyme Q10 (CoQ10) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the cerebrospinal fluid (CSF) of 17 patients with sALS and 17 age-matched controls with no neurological diseases. The percentage of oxidized CoQ10 in the CSF of sALS patients was greater than that in the CSF of controls (p<0.002) and was negatively correlated with the duration of illness (rho=-0.61, p<0.01). The concentration of 8-OHdG in the CSF of sALS patients was greater than that in the CSF of controls (p<0.005) and was positively correlated with the duration of illness (rho=0.53, p<0.005). The percentage of oxidized CoQ10 was correlated with the concentrations of 8-OHdG in the CSF of sALS patients (rho=-0.53, p<0.05). These results suggest that both mitochondrial oxidative damage and oxidative DNA damage play important roles in the pathogenesis of sporadic amyotrophic lateral sclerosis.

Oxidative stress biomarkers in sporadic ALS

We aimed to investigate oxidative stress biomarkers in a cross-sectional pilot study of 50 participants with sporadic ALS (SALS) compared to 46 control subjects. We measured urinary 8-oxodeoxyguanosine (8-oxodG), urinary 15-F(2t)-isoprostane (IsoP), and plasma protein carbonyl by ELISA methods. We also determined if ELISA measurement of 8-oxodG could be validated against measures from high-pressure liquid chromatography coupled with electrochemical detection, the current standard method. We found that 8-oxodG and IsoP levels adjusted for creatinine were significantly elevated in SALS participants. These differences persisted after age and gender were controlled in regression analyses. These markers are highly and positively correlated with each other. 8-oxodG measured by the two techniques from the same urine sample were positively correlated (p<.0001). Protein carbonyl was not different between SALS participants and controls. In conclusion, using ELISA, we confirmed that certain oxidative stress biomarkers were elevated in SALS participants. ELISA may be reliable and thus useful in epidemiology studies requiring large numbers of samples to determine the significance of increased oxidative stress markers in SALS. Further studies are required.

Vitamin E deficiency and risk of equine motor neuron disease

BACKGROUND

Equine motor neuron disease (EMND) is a spontaneous neurologic disorder of adult horses which results from the degeneration of motor neurons in the spinal cord and brain stem. Clinical manifestations, pathological findings, and epidemiologic attributes resemble those of human motor neuron disease (MND). As in MND the etiology of the disease is not known. We evaluated the predisposition role of vitamin E deficiency on the risk of EMND.

METHODS

Eleven horses at risk of EMND were identified and enrolled in a field trial at different times. The horses were maintained on a diet deficient in vitamin E and monitored periodically for levels of antioxidants--alpha-tocopherols, vitamins A, C, beta-carotene, glutathione peroxidase (GSH-Px), and erythrocytic superoxide dismutase (SOD1). In addition to the self-control another parallel control group was included. Survival analysis was used to assess the probability of developing EMND past a specific period of time.

RESULTS

There was large variability in the levels of vitamins A and C, beta-carotene, GSH-Px, and SOD1. Plasma vitamin E levels dropped significantly over time. Ten horses developed EMND within 44 months of enrollment. The median time to develop EMND was 38.5 months. None of the controls developed EMND.

CONCLUSION

The study elucidated the role of vitamin E deficiency on the risk of EMND. Reproducing this disease in a natural animal model for the first time will enable us to carry out studies to test specific hypotheses regarding the mechanism by which the disease occurs.

Determination of glutathione in hemolysed erythrocyte with amperometric sensor based on TTF-TCNQ

BACKGROUND

GSH has a relevant role in human metabolism as an indicator of disease risks. An amperometric sensor for glutathione (GSH) determination is described as an alternative method featuring simple construction procedure and short time analysis.

METHOD

The developed sensor was used to determine glutathione at low potential using a TTF-TCNQ complex.

RESULTS

The sensor exhibits a linear response range from 5 to 340 micromol/l under applied potential of 200 mV vs. SCE. The sensitivity and detection limit were 90.1 microA l/mmol cm(2) and 0.3 micromol/l, respectively.

CONCLUSION

When the sensor was tested in hemolysed erythrocyte samples for GSH determination, a good correlation in results was observed between the sensor and the spectrophotometric method. The sensor showed recovery values between 98% and 102%.

Total antioxidant capacity of cerebrospinal fluid is decreased in patients with motor neuron disease

Oxidative stress has been associated with motor neuron disease (MND). The human body has several antioxidant defense systems to repair the damage caused by oxidative stress. The activity of these systems is thought to be reduced in neurodegenerative diseases, which may increase the level of oxidative damage and be a contributing factor to motor neuron death. In the present study, we compared the total antioxidant capacity (TAC) of human serum and cerebrospinal fluid (CSF) of MND patients with that of a control group including patients with migraine, tension headache and psychiatric disorders. Within-subject serum and CSF TAC were strongly correlated (r=0.639; p=0.000), and CSF TAC was significantly lower in MND patients as compared to controls after adjustment for known influencing factors (112.7 micromol Fe/L+/-11.7 versus 135.2 micromol Fe/L+/-19.7; p=0.012). No differences in serum or CSF TAC were observed among the clinical forms of MND considered in this work. In conclusion, the CSF TAC was strongly correlated with serum TAC, and a decrease in CSF TAC was demonstrated in MND patients compared to controls that was not independent from serum antioxidants, this translating in a systemic (but prevailing in the CNS) oxidative damage in this pathology.