Systemic Oxidative Stress Associated with the Neurological Diseases of Aging

Reconsidering red blood cells as the diagnostic potential for neurodegenerative disorders

BACKGROUND

Red blood cells (RBCs) are usually considered simple cells and transporters of gases to tissues.

HYPOTHESIS

However, recent research has suggested that RBCs may have diagnostic potential in major neurodegenerative disorders (NDDs).

RESULTS

This review summarizes the current knowledge on changes in RBC in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and other NDDs. It discusses the deposition of neuronal proteins like amyloid-β, tau, and α-synuclein, polyamines, changes in the proteins of RBCs like band-3, membrane transporter proteins, heat shock proteins, oxidative stress biomarkers, and altered metabolic pathways in RBCs during neurodegeneration. It also highlights the comparison of RBC diagnostic markers to other in-market diagnoses and discusses the challenges in utilizing RBCs as diagnostic tools, such as the need for standardized protocols and further validation studies.

SIGNIFICANCE STATEMENT

The evidence suggests that RBCs have diagnostic potential in neurodegenerative disorders, and this study can pave the foundation for further research which may lead to the development of novel diagnostic approaches and treatments.

New Thiosemicarbazide Derivatives with Multidirectional Biological Action

Over the years, several new medicinal substances have been introduced for the treatment of diseases caused by bacteria and parasites. Unfortunately, due to the production of numerous defense mechanisms by microorganisms and parasites, they still pose a serious threat to humanity around the world. Therefore, laboratories all over the world are still working on finding new, effective methods of pharmacotherapy. This research work aimed to synthesize new compounds derived from 3-trifluoromethylbenzoic acid hydrazide and to determine their biological activity. The first stage of the research was to obtain seven new compounds, including six linear compounds and one derivative of 1,2,4-triazole. The PASS software was used to estimate the potential probabilities of biological activity of the newly obtained derivatives. Next, studies were carried out to determine the nematocidal potential of the compounds with the use of nematodes of the genus Rhabditis sp. and antibacterial activity using the ACCT standard strains. To determine the lack of cytotoxicity, tests were performed on two cell lines. Additionally, an antioxidant activity test was performed due to the importance of scavenging free radicals in infections with pathogenic microorganisms. The conducted research proved the anthelmintic and antibacterial potential of the newly obtained compounds. The most effective were two compounds with a 3-chlorophenyl substituent, both linear and cyclic derivatives. They demonstrated higher efficacy than the drugs used in treatment.

Comparative Investigation of Raw and Processed Radix Polygoni Multiflori on the Treatment of Vascular Dementia by Liquid Chromatograph-Mass Spectrometry Based Metabolomic Approach

Radix Polygoni Multiflori (PM) is a well-known nootropic used in traditional Chinese medicine (TCM). Considering the efficacy and application discrepancy between raw (RPM) and processed PM (PPM), the similarities and differences between them in the treatment of vascular dementia (VaD) is intriguing. In this study, a VaD rat model was constructed by 2-vessel occlusion (2-VO). During 28 days of treatment, plasma was collected on days 7, 14, 21, and 28 after the start of dosing and the metabolic profile was analyzed by HPLC-MS/MS-based metabolomics. The Morris Water Maze Test, hematoxylin-eosin and Nissl staining, and biochemical analysis were used to assess cognitive function, pathogenic alterations and oxidative stress, respectively. RPM and PPM effectivelyreducedthe 2VO-induced cognitive impairment and mitigated histological alterations in hippocampus tissue. The 2-VO model significantly elevated MDA level and decreased SOD activity and GSH level, indicating severe oxidative stress, which could also be attenuated by RPM and PPM treatment. RPM outperformed PPM in decreasing MDA levels while PPM outperformed RPM in increasing GSH levels. Differential metabolites were subjected to Metabolite Set Enrichment Analysis (MSEA) and genes corresponding to proteins having interactions with metabolites were further annotated with Gene Ontology (GO). Both RPM and PPM ameliorated VaD-relevant vitamin B6 metabolism, pentose phosphate pathways, and taurine and hypotaurine metabolism. In addition, the metabolism of cysteine and methionine was regulated only by RPM, and riboflavin metabolism was modulated only by PPM. The results suggested that raw and processed PM had comparable efficacy in the treatment of VaD but also with some mechanistic differenece.

Comparative study of rivastigmine and galantamine on the transgenic Drosophila model of Alzheimer's disease

Alzheimer's Disease (AD) is characterized as a progressive neurodegenerative disease most commonly associated with memory deficits and cognitive decline. The formation of amyloid plaques and neurofibrillary tangles are important pathological markers of AD. The accumulation of amyloid plaques and neurofibrillary tangles leads to the loss of neurons including the cholinergic neurons thus decreasing the levels of acetylcholine (a neurotransmitter). To reduce the AD symptoms cholinesterase inhibitors are widely used to decrease the hydrolysis of acetylcholine released from presynaptic neurons. In the present study we have studied the effect of rivastigmine and galantamine (commonly used cholinesterase inhibitors) on the transgenic Drosophila model of AD expressing human Aβ-42 in the neurons. The effect of similar doses of rivastigmine and galantamine (i.e. 0.1,1 and 10 ​mM) was studied on the climbing ability, lifespan, oxidative stress markers, caspase 9 and 3, acetylcholinesterase activity and on the formation of Aβ-42 aggregates. The results suggest that the rivastigmine is more potent in reducing the oxidative stress and improving climbing ability of AD flies. Both the drugs were found to be effective in increasing the lifespan of AD flies. Galantamine was found to be a more potent inhibitor of acetylcholinesterase compared to rivastigmine. Galantamine prevents the formation of Aβ-42 aggregates more effectively compared to rivastigmine.

Effect of Hydroxyl Groups Esterification with Fatty Acids on the Cytotoxicity and Antioxidant Activity of Flavones

Flavonoids and polyunsaturated fatty acids due to low cytotoxicity in vitro studies are suggested as potential substances in the prevention of diseases associated with oxidative stress. We examined novel 6-hydroxy-flavanone and 7-hydroxy-flavone conjugates with selected fatty acids (FA) of different length and saturation and examined their cytotoxic and antioxidant potential. Our findings indicate that the conjugation with FA affects the biological activity of both the original flavonoids. The conjugation of 6-hydroxy-flavanone increased its cytotoxicity towards prostate cancer PC3 cells. The most noticeable effect was found for oleate conjugate. A similar trend was observed for 7-hydroxy-flavone conjugates with the most evident effect for oleate and stearate. The cytotoxic potential of all tested conjugates was not specific towards PC3 because the viability of human keratinocytes HaCaT cells decreased after exposure to all conjugates. Additionally, we showed that esterification of the two flavonoids decreased their antioxidant activity compared to that of the original compounds. Of all the tested compounds, only 6-sorbic flavanone showed a slight increase in antioxidant potential compared to that of the original compound. Our data show that conjugated flavonoids are better absorbed and enhance cytotoxic effects, but the presence of FA lowered the antioxidant potential.

Neurological Disorders in an Elderly Cohort Experienced Past Stressful Events: A Retrospective-prospective Study

BACKGROUND

Psychological stress may be a risk factor for dementia, but the association between exposure to stressful life events and the development of cognitive dysfunction has not been conclusively demonstrated. We hypothesize that if a stressful event has an impact on the subjects, its effects would be different in the three diseases.

OBJECTIVE

This study aims to assess the effects of stressful events in senior patients who later developed ischemic stroke, Alzheimer's, or Parkinson's disease.

MATERIAL AND METHODS

Together with demographic variables (age, sex, race, socioeconomic and cultural levels), five types of past stressful events, such as death or serious illness of close relatives, job dismissal, change of financial status, retirement, and change of residence, were recorded in 1024 patients with Alzheimer's disease, Parkinson's disease, and ischemic stroke. Time-todiagnosis (months from the event to the first symptoms: retrospective study) and evolution time (years of follow-up of each patient: prospective study) were recorded. The variance and nonparametric methods were analyzed to the variables time-to-diagnosis and evolution time to analyze differences between these diseases.

RESULTS

The demographic variables, such as age, sex, race, economic and cultural levels, were found to be statistically non-significant; differences in the economic level were significant (P<0.05). Significant differences (P<0.001) were found in the mean time-to-diagnosis between diseases (Alzheimer's disease>Parkinson's disease >Stroke), and minor differences (P<0.05) in evolution time.

CONCLUSION

Differences in time-to-diagnosis between the diseases indicate that the stressful effect of having experienced the death or serious illness of a close relative has an impact on their emergence. The measurement of time-to-diagnosis and evolution time proves useful in detecting differences between diseases.

Overview of the Neuroprotective Effects of the MAO-Inhibiting Antidepressant Phenelzine

Phenelzine (PLZ) is a monoamine oxidase (MAO)-inhibiting antidepressant with anxiolytic properties. This multifaceted drug has a number of pharmacological and neurochemical effects in addition to inhibition of MAO, and findings on these effects have contributed to a body of evidence indicating that PLZ also has neuroprotective/neurorescue properties. These attributes are reviewed in this paper and include catabolism to the active metabolite β-phenylethylidenehydrazine (PEH) and effects of PLZ and PEH on the GABA-glutamate balance in brain, sequestration of reactive aldehydes, and inhibition of primary amine oxidase. Also discussed are the encouraging findings of the effects of PLZ in animal models of stroke, spinal cord injury, traumatic brain injury, and multiple sclerosis, as well other actions such as reduction of nitrative stress, reduction of the effects of a toxin on dopaminergic neurons, potential anticonvulsant actions, and effects on brain-derived neurotrophic factor, neural cell adhesion molecules, an anti-apoptotic factor, and brain levels of ornithine and N-acetylamino acids.

Connection between the Altered HDL Antioxidant and Anti-Inflammatory Properties and the Risk to Develop Alzheimer's Disease: A Narrative Review

The protein composition of high-density lipoprotein (HDL) is extremely fluid. The quantity and quality of protein constituents drive the multiple biological functions of these lipoproteins, which include the ability to contrast atherogenesis, sustained inflammation, and toxic effects of reactive species. Several diseases where inflammation and oxidative stress participate in the pathogenetic process are characterized by perturbation in the HDL proteome. This change inevitably affects the functionality of the lipoprotein. An enlightening example in this frame comes from the literature on Alzheimer's disease (AD). Growing lines of epidemiological evidence suggest that loss of HDL-associated proteins, such as lipoprotein phospholipase A2 (Lp-PLA2), glutathione peroxidase-3 (GPx-3), and paraoxonase-1 and paraoxonase-3 (PON1, PON3), may be a feature of AD, even at the early stage. Moreover, the decrease in these enzymes with antioxidant/defensive action appears to be accompanied by a parallel increase of prooxidant and proinflammatory mediators, in particular myeloperoxidase (MPO) and serum amyloid A (SAA). This type of derangement of balance between two opposite forces makes HDL dysfunctional, i.e., unable to exert its “natural” vasculoprotective property. In this review, we summarized and critically analyzed the most significant findings linking HDL accessory proteins and AD. We also discuss the most convincing hypothesis explaining the mechanism by which an observed systemic occurrence may have repercussions in the brain.

Zingiber officinale Ethanolic Extract Attenuated Reserpine-Induced Depression-Like Condition and Associated Hippocampal Aberrations in Experimental Wistar Rats

BACKGROUND

Repeated and regimented treatment with reserpine causes depression-like condition characterized by persistent mood disorder, feelings of severe despondency and dejection, thus altering the hippocampal morphology. Our study compared a well-known antidepressant (fluoxetine), with the potential of Zingiber officinale to ameliorate reserpine-induced depression and the associated hippocampal cornu ammonis 1 (CA1) neuronal cell damage.

METHODS

Forty-eight male Wistar rats, weighing 130-160 g, were randomly assigned to 6 groups (n=8), housed in plastic cages under natural light and dark cycles at room temperature with access to feed and water ad libitum. Group-A (control) received distilled water. Group-B and Group-C orally received 400 mg/kg of Zingiber officinale and 10 mg/kg of fluoxetine, respectively, for 7 days, while Group-D intraperitoneally received 0.2 mg/kg of reserpine for 14 days. Group-E and Group-F intraperitoneally received 0.2 mg/kg of reserpine for 14 days followed by 400 mg/kg of Zingiber officinale and 10 mg/kg of fluoxetine respectively for 7 days. All animals were sacrificed by cervical dislocation at the end of experiment, and the brains hippocampi were dissected, excised and processed for various analyses including histology [H&E], histochemistry of GFAP expression by astrocytes and specific gene expressions including p53 gene, glutathione reductase (GSR), glutathione peroxidase and catalase (CAT).

RESULTS

Reserpine significantly depleted the expression of P53 and glutathione reductase (GSR) genes while significantly increasing the expression of glutathione peroxidase 1 (GPx-1) gene (P≤0.05). Also, a marked increase in the expression of catalase (CAT) gene was observed. Furthermore, histoarchitecture (photomicrographs) of hippocampus CA1 region showed disruption in the arrangement of pyramidal neurons and alterations in their morphologies when animals were treated with reserpine (Group D). There was also accompanying increased astrocyte densities within the CA1 region following reserpine treatment. These features indicated deleterious effects of reserpine. Both Zingiber officinale and fluoxetine treatments ameliorated these effects.

CONCLUSION

These findings showed structural and molecular alterations associated with reserpine-induced depression. Also, Zingiber officinale was effective to provide ameliorative and protective effects against the neurotoxic effects of reserpine in the hippocampus, making it a potential candidate for treating depression and its associated neurodegenerative diseases.

Inflammation in Neurological Disorders: The Thin Boundary Between Brain and Periphery

Significance: Accumulating evidence suggests that inflammation is a major contributor in the pathogenesis of several highly prevalent, but also rare, neurological diseases. In particular, the neurodegenerative processes of Alzheimer's disease (AD), vascular dementia (VAD), Parkinson's disease (PD), and multiple sclerosis (MS) are fueled by neuroinflammation, which, in turn, is accompanied by a parallel systemic immune dysregulation. This cross-talk between periphery and the brain becomes substantial when the blood-brain barrier loses its integrity, as often occurs in the course of these diseases. It has been hypothesized that the perpetual bidirectional flux of inflammatory mediators is not a mere "static" collateral effect of the neurodegeneration, but represents a proactive phenomenon sparking and driving the neuropathological processes. However, the upstream/downstream relationship between inflammatory events and neurological pathology is still unclear. Recent Advances: Solid recent evidence clearly suggests that metabolic factors, systemic infections, Microbiota dysbiosis, and oxidative stress are implicated, although to a different extent, in the development in brain diseases. Critical Issues: Here, we reviewed the most solid published evidence supporting the implication of the axis systemic inflammation-neuroinflammation-neurodegeneration in the pathogenesis of AD, VAD, PD, and MS, highlighting the possible cause of the putative downstream component of the axis. Future Directions: Reaching a definitive clinical/epidemiological appreciation of the etiopathogenic significance of the connection between peripheral and brain inflammation in neurologic disorders is pivotal since it could open novel therapeutic avenues for these diseases.

Exercise-Induced Regulation of Redox Status in Cardiovascular Diseases: The Role of Exercise Training and Detraining

Although low levels of reactive oxygen species (ROS) are beneficial for the organism ensuring normal cell and vascular function, the overproduction of ROS and increased oxidative stress levels play a significant role in the onset and progression of cardiovascular diseases (CVDs). This paper aims at providing a thorough review of the available literature investigating the effects of acute and chronic exercise training and detraining on redox regulation, in the context of CVDs. An acute bout of either cardiovascular or resistance exercise training induces a transient oxidative stress and inflammatory response accompanied by reduced antioxidant capacity and enhanced oxidative damage. There is evidence showing that these responses to exercise are proportional to exercise intensity and inversely related to an individual’s physical conditioning status. However, when chronically performed, both types of exercise amplify the antioxidant defense mechanism, reduce oxidative stress and preserve redox status. On the other hand, detraining results in maladaptations within a time-frame that depends on the exercise training intensity and mode, as high-intensity training is superior to low-intensity and resistance training is superior to cardiovascular training in preserving exercise-induced adaptations during detraining periods. Collectively, these findings suggest that exercise training, either cardiovascular or resistance or even a combination of them, is a promising, safe and efficient tool in the prevention and treatment of CVDs.

Postoperative delirium after hip surgery is a potential risk factor for incident dementia: A systematic review and meta-analysis of prospective studies

BACKGROUND

Although a few trials have explored the relationship between postoperative delirium (POD) and incident dementia in patients with hip surgery, the numbers of participants in each study are relatively small. Thus, we performed a meta-analysis to examine whether POD after hip surgery is a risk factor for incident dementia.

METHODS

Six prospective cohort studies investigating the development of incident dementia in patients with POD after hip surgery were retrieved from PubMed, Embase, and the Cochrane Library. We performed a pairwise meta-analysis using fixed- and random- effect models.

RESULTS

POD significantly increased the risk of incident dementia and cognitive decline (overall odds ratio [ORs] = 8.957; 95 % confidence interval [CI], 5.444-14.737; P <  0.001 in fixed-effects model; overall ORs = 8.962; 95 % CI, 5.344-15.029; P <  0.001 in random-effects model). A publication bias was not evident in this study.

CONCLUSIONS

Our meta-analysis revealed that POD after hip surgery is a risk factor for incident dementia. Early identification of cognitive function should be needed after surgery and appropriate prevention and treatment for dementia will be required, especially in cases with POD.

Oxidative stress in biological systems and its relation with pathophysiological functions: the effect of physical activity on cellular redox homeostasis

The body of evidence from the past three decades demonstrates that oxidative stress can be involved in several diseases. This study aims to summarise the current state of knowledge on the association between oxidative stress and the pathogenesis of some characteristic to the biological systems diseases and aging process. This review also presents the effect of physical activity on redox homeostasis. There is strong evidence from studies for participation of reactive oxygen and nitrogen species in pathogenesis of acute and chronic diseases based on animal models and human studies. Elevated levels of pro-oxidants and various markers of the oxidative stress and cells and tissues damage linked with pathogenesis of cancer, atherosclerosis, neurodegenerative diseases hypertension, diabetes mellitus, cardiovascular disease, atherosclerosis, reproductive system diseases, and aging were reported. Evidence confirmed that inflammation contributes widely to multiple chronic diseases and is closely linked with oxidative stress. Regular moderate physical activity regulates oxidative stress enhancing cellular antioxidant defence mechanisms, whereas acute exercise not preceded by training can alter cellular redox homeostasis towards higher level of oxidative stress. Future studies are needed to clarify the multifaceted effects of reactive oxygen/nitrogen species on cells and tissues and to continue study on the biochemical roles of antioxidants and physical activity in prevention of oxidative stress-related tissue injury.

Glutamine Improves Oxidative Stress through the Wnt3a/β-Catenin Signaling Pathway in Alzheimer's Disease In Vitro and In Vivo

Background/Aims

Alzheimer's disease (AD) is the most common neurodegenerative disease, and all researchers working in this field agree that oxidative stress is intimately associated with Alzheimer disease. In this study, we hypothesized that glutamine (Gln) offers protection against oxidative stress injury in SAMP8 mice as well as the underlying mechanism.

Methods

The SAMP8 mice received glutamine intragastrically for 8 consecutive weeks to evaluate the protective effect of glutamine on oxidative stress in AD mice involving Wnt3a/β-catenin signaling pathway. In addition, rat pheochromocytoma tumor cell line PC12 was pretreated with 32 μM glutamine for 2 h followed by 24 h incubation with 40 μM Aβ25-35 to obtain in vitro data.

Results

In vivo the administration of glutamine was found to ameliorate behavioral deficits and neuron damage, increase superoxide dismutase (SOD) and glutathione peroxidase (GSH-XP) activity, reduce the malondialdehyde (MDA) content, and activate the Wnt3a/β-catenin signaling pathway in SAMP8 mice. In vitro glutamine treatment decreased the toxicity of Aβ25-35 on PC12 cells and prevented apoptosis. Additionally, glutamine treatment increased SOD and GSH-XP activity and decreased MDA content and increased Wnt3a and β-catenin protein levels. Interestingly, the DKK-1 (Wnt3a/β-catenin pathway inhibitor) decreased the antioxidant capacity of glutamine in Aβ25-35-treated PC12 cells.

Conclusion

This study suggests that glutamine could protect against oxidative stress-induced injury in AD mice via the Wnt3a/β-catenin signaling pathway.

Attenuation of the effects of oxidative stress by the MAO-inhibiting antidepressant and carbonyl scavenger phenelzine

Phenelzine (β-phenylethylhydrazine) is a monoamine oxidase (MAO)-inhibiting antidepressant with anxiolytic properties. It possesses a number of important pharmacological properties which may alter the effects of oxidative stress. After conducting a comprehensive literature search, the authors of this review paper aim to provide an overview and discussion of the mechanisms by which phenelzine may attenuate oxidative stress. It inhibits γ-aminobutyric acid (GABA) transaminase, resulting in elevated brain GABA levels, inhibits both MAO and primary amine oxidase and, due to its hydrazine-containing structure, reacts chemically to sequester a number of reactive aldehydes (e.g. acrolein and 4-hydroxy-2-nonenal) proposed to be implicated in oxidative stress in a number of neurodegenerative disorders. Phenelzine is unusual in that it is both an inhibitor of and a substrate for MAO, the latter action producing at least one active metabolite, β-phenylethylidenehydrazine (PEH). This metabolite inhibits GABA transaminase, is a very weak inhibitor of MAO but a strong inhibitor of primary amine oxidase, and sequesters aldehydes. Phenelzine may ameliorate the effects of oxidative stress by reducing formation of reactive metabolites (aldehydes, hydrogen peroxide, ammonia/ammonia derivatives) produced by the interaction of MAO with biogenic amines, by sequestering various other reactive aldehydes and by inhibiting primary amine oxidase. In PC12 cells treated with the neurotoxin MPP⁺, phenelzine has been reported to reduce several adverse effects of MPP⁺. It has also been reported to reduce lipid peroxidative damage induced in plasma and platelet proteins by peroxynitrite. In animal models, phenelzine has a neuroprotective effect in global ischemia and in cortical impact traumatic brain injury. Recent studies reported in the literature on the possible involvement of acrolein in spinal cord injury and multiple sclerosis indicate that phenelzine can attenuate adverse effects of acrolein in these models. Results from studies in our laboratories on effects of phenelzine and PEH on primary amine oxidase (which catalyzes formation of toxic aldehydes and is overexpressed in Alzheimer's disease), on sequestration of the toxic aldehyde acrolein, and on reduction of acrolein-induced toxicity in mouse cortical neurons are also reported.

Protective effect of rutin against brain injury induced by acrylamide or gamma radiation: role of PI3K/AKT/GSK-3β/NRF-2 signalling pathway

This study was designed to evaluate the effect of rutin on PI3K/AKT-signalling in case of acrylamide or γ-radiation-induced neurotoxicity. To induce brain damage, animals were received acrylamide (25 mg/kg b.wt./orally/day) or 5 Gy of γ-radiation exposure accompanied with an administration of rutin (200 mg/kg b.wt./orally/day). Our data revealed that, compared to acrylamide or γ-radiation, rutin activated PI3K/AKT/GSK-3β/NRF-2-pathway through increased protein levels of p-PI3K, p-AKT and p-GSK-3β and up-regulated the expression of NRF-2. This was achieved by modulating MDA, GST, IL-1β, IL-6 and reduced the interference of ROS with IGF-1 and NGF stimulating the PI3K/AKT-signaling. Furthermore, histopathological examinations of brain tissues showed that rutin has modulated tissue architecture after acrylamide or γ-radiation induced tissue damage. It could be concluded that rutin provides protection effect against acrylamide or γ-radiation-induced neurotoxicity via activation of the PI3K/AKT/GSK-3β/NRF-2-pathway by altering the phosphorylation state through its ability to scavenge free radicals generation, modulating gene expression and its anti-inflammatory effects.

Milk Intake at Midlife and Cognitive Decline over 20 Years. The Atherosclerosis Risk in Communities (ARIC) Study

Background: Faster rates of cognitive decline are likely to result in earlier onset of cognitive impairment and dementia. d-galactose, a derivative of lactose, is used in animal studies to induce neurodegeneration. Milk is the primary source of lactose in the human diet, and its effects on cognitive decline have not been fully evaluated. Objective: Assess the association of milk intake with change in cognitive function over 20 years. Methods: A total of 13,751 participants of the Atherosclerosis Risk in Communities (ARIC) cohort completed a food frequency questionnaire and three neurocognitive evaluations from 1990 through 2013. Two single nucleotide polymorphisms (SNPs) were used to determine lactase persistence (LCT-13910 C/T for Whites and LCT-14010 G/C for Blacks). Mixed-effects models were used to study the association of milk intake with cognitive change. Multiple imputations by chained equations were used to account for attrition. Results: Milk intake greater than 1 glass/day was associated with greater decline in the global z-score over a 20-year period. The difference in decline was 0.10 (95% CI: 0.16, 0.03) z-scores, or an additional 10% decline, relative to the group reporting “almost never” consuming milk. Conclusions: Replication of these results is warranted in diverse populations with greater milk intake and higher variability of lactase persistence genotype.

Gamma Glutamyl Transpeptidase, Smokeless Tobacco, Chronic Periodontitis: Exploring the Link

INTRODUCTION

Oxidative Stress (OS) is implicated in the pathogenesis of many systemic and oral diseases such as periodontal disease. Smokeless tobacco extract produces apoptosis and causes an imbalance between reactive oxygen species and antioxidants, such as Gamma Glutamyl Transpeptidase (GGT). Epidemiological research implied serum GGT within its normal range to be an early sensitive enzyme related to OS.

AIM

To assess how GGT fares as a biomarker in periodontitis subjects with or without the usage of smokeless tobacco and correlate it with clinical parameters.

MATERIALS AND METHODS

Ninety subjects were divided into three groups of healthy, chronic periodontitis, and smokeless tobacco users with chronic periodontitis from the dental outpatient department of P.M. Nadagouda Memorial Dental College and Hospital. Serum samples of patients were collected after obtaining consent and analyzed for GGT. Statistical Analysis was performed using ANOVA, and Pearson's correlation coefficient.

RESULTS

GGT levels were found to be significantly higher in chronic periodontitis patients compared to smokeless tobacco users with chronic periodontitis and healthy subjects. Conclusion: GGT may be used as a quick, easy and precise marker for measuring OS in patients with chronic periodontitis and smokeless tobacco users.

The neurotoxicity of iron, copper and cobalt in Parkinson's disease through ROS-mediated mechanisms

Parkinson's disease (PD) is the second most common neurodegenerative disease with gradual loss of dopaminergic neurons. Despite extensive research in the past decades, the etiology of PD remains elusive. Nevertheless, multiple lines of evidence suggest that oxidative stress is one of the common causes in the pathogenesis of PD. It has also been suggested that heavy metal-associated oxidative stress may be implicated in the etiology and pathogenesis of PD. Here we review the roles of redox metals, including iron, copper and cobalt, in PD. Iron is a highly reactive element and deregulation of iron homeostasis is accompanied by concomitant oxidation processes in PD. Copper is a key metal in cell division process, and it has been shown to have an important role in neurodegenerative diseases such as PD. Cobalt induces the generation of reactive oxygen species (ROS) and DNA damage in brain tissues.

Highly specific changes in antioxidant levels and lipid peroxidation in Parkinson's disease and its progression: Disease and staging biomarkers and new drug targets

There is evidence that immune-inflammatory, stress of reactive oxygen and nitrogen species (IO&NS) processes play a role in the neurodegenerative processes observed in Parkinson's disease (PD). The aim of the present study was to investigate peripheral IO&NS biomarkers in PD. We included 56 healthy individuals and 56 PD patients divided in two groups: early PD stage and late PD stage. Plasma lipid hydroperoxides (LOOH), malondialdehyde (MDA), nitric oxide metabolites (NOx), sulfhydryl (SH) groups, catalase (CAT) activity, superoxide dismutase (SOD) activity, paraoxonase (PON)1 activity, total radical trapping antioxidant parameter (TRAP) and C-reactive protein (CRP) were measured. PD is characterized by increased LOOH, MDA and SOD activity and lowered CAT activity. A combination of five O&NS biomarkers highly significantly predicts PD with a sensitivity of 94.5% and a specificity of 86.8% (i.e., MDA, SOD activity, TRAP, SH-groups and CAT activity). The single best biomarker of PD is MDA, while LOOH and SOD activity are significantly associated with late PD stage, but not early PD stage. Antiparkinson drugs did not affect O&NS biomarkers, but levodopa+carbidopa significantly increased CRP. It is suggested that MDA may serve as a disease biomarker, while LOOH and SOD activity are associated with late PD stage characteristic. New treatments for PD should not only target dopamine but also lipid peroxidation.

Involvement of Cytochrome P450 in Reactive Oxygen Species Formation and Cancer

This review examines the involvement of cytochrome P450 (CYP) enzymes in the formation of reactive oxygen species in biological systems and discusses the possible involvement of reactive oxygen species and CYP enzymes in cancer. Reactive oxygen species are formed in biological systems as byproducts of the reduction of molecular oxygen and include the superoxide radical anion (∙O2-), hydrogen peroxide (H2O2), hydroxyl radical (∙OH), hydroperoxyl radical (HOO∙), singlet oxygen ((1)O2), and peroxyl radical (ROO∙). Two endogenous sources of reactive oxygen species are the mammalian CYP-dependent microsomal electron transport system and the mitochondrial electron transport chain. CYP enzymes catalyze the oxygenation of an organic substrate and the simultaneous reduction of molecular oxygen. If the transfer of oxygen to a substrate is not tightly controlled, uncoupling occurs and leads to the formation of reactive oxygen species. Reactive oxygen species are capable of causing oxidative damage to cellular membranes and macromolecules that can lead to the development of human diseases such as cancer. In normal cells, intracellular levels of reactive oxygen species are maintained in balance with intracellular biochemical antioxidants to prevent cellular damage. Oxidative stress occurs when this critical balance is disrupted. Topics covered in this review include the role of reactive oxygen species in intracellular cell signaling and the relationship between CYP enzymes and cancer. Outlines of CYP expression in neoplastic tissues, CYP enzyme polymorphism and cancer risk, CYP enzymes in cancer therapy and the metabolic activation of chemical procarcinogens by CYP enzymes are also provided.

Is gamma-glutamyl transpeptidase a biomarker for oxidative stress in periodontitis?

CONTEXT

Periodontal disease and oxidative stress (OS) are part of a vicious cycle with each causing a deleterious effect on the other causing changes in the levels of antioxidants, and enzymes of antioxidant defense. Biomarkers and methods used for measuring OS are very expensive.

AIMS

To see how gamma-glutamyltransferase (GGT) fares, as a biomarker for OS in periodontits along with other routinely used biomarkers.

DESIGN

A cross-sectional study involving 300 people of which 150 were cases and 150 were controls.

SETTING

Candidates enrolled were patients visiting the OPD of MGV's Dental College and Hospital, Nasik, India between January 2011 and December 2012.

MATERIALS AND METHODS

Serum samples of patients with periodontitis, and controls were analyzed for malondialdehyde, superoxide dismutase (SOD), glutathione peroxidase (GPx), uric acid, and GGT.

STATISTICAL ANALYSIS USED

Analysis was performed using Student's t test. P <0.05 were considered to be significant.

RESULTS

Malondialdehyde values were found to be significantly higher cases, while SOD, GPx and uric acid levels were found to be lower than controls. GGT levels were significantly higher in cases as compared to controls.

CONCLUSIONS

GGT may be used as a cheap, quick, easy and precise marker for measuring OS.

Role of zinc and copper ions in the pathogenetic mechanisms of Alzheimer's and Parkinson's diseases

Disbalance of zinc (Zn2+) and copper (Cu2+) ions in the central nervous system is involved in the pathogenesis of numerous neurodegenerative disorders such as multisystem atrophy, amyotrophic lateral sclerosis, Creutzfeldt-Jakob disease, Wilson-Konovalov disease, Alzheimer's disease, and Parkinson's disease. Among these, Alzheimer's disease (AD) and Parkinson's disease (PD) are the most frequent age-related neurodegenerative pathologies with disorders in Zn2+ and Cu2+ homeostasis playing a pivotal role in the mechanisms of pathogenesis. In this review we generalized and systematized current literature data concerning this problem. The interactions of Zn2+ and Cu2+ with amyloid precursor protein (APP), β-amyloid (Abeta), tau-protein, metallothioneins, and GSK3β are considered, as well as the role of these interactions in the generation of free radicals in AD and PD. Analysis of the literature suggests that the main factors of AD and PD pathogenesis (oxidative stress, structural disorders and aggregation of proteins, mitochondrial dysfunction, energy deficiency) that initiate a cascade of events resulting finally in the dysfunction of neuronal networks are mediated by the disbalance of Zn2+ and Cu2+.

A conserved role for p48 homologs in protecting dopaminergic neurons from oxidative stress

Parkinson's disease (PD) is the most common neurodegenerative movement disorder characterized by the progressive loss of dopaminergic (DA) neurons. Both environmental and genetic factors are thought to contribute to the pathogenesis of PD. Although several genes linked to rare familial PD have been identified, endogenous risk factors for sporadic PD, which account for the majority of PD cases, remain largely unknown. Genome-wide association studies have identified many single nucleotide polymorphisms associated with sporadic PD in neurodevelopmental genes including the transcription factor p48/ptf1a. Here we investigate whether p48 plays a role in the survival of DA neurons in Drosophila melanogaster and Caenorhabditis elegans. We show that a Drosophila p48 homolog, 48-related-2 (Fer2), is expressed in and required for the development and survival of DA neurons in the protocerebral anterior medial (PAM) cluster. Loss of Fer2 expression in adulthood causes progressive PAM neuron degeneration in aging flies along with mitochondrial dysfunction and elevated reactive oxygen species (ROS) production, leading to the progressive locomotor deficits. The oxidative stress challenge upregulates Fer2 expression and exacerbates the PAM neuron degeneration in Fer2 loss-of-function mutants. hlh-13, the worm homolog of p48, is also expressed in DA neurons. Unlike the fly counterpart, hlh-13 loss-of-function does not impair development or survival of DA neurons under normal growth conditions. Yet, similar to Fer2, hlh-13 expression is upregulated upon an acute oxidative challenge and is required for the survival of DA neurons under oxidative stress in adult worms. Taken together, our results indicate that p48 homologs share a role in protecting DA neurons from oxidative stress and degeneration, and suggest that loss-of-function of p48 homologs in flies and worms provides novel tools to study gene-environmental interactions affecting DA neuron survival.

Parkinson's disease is a common movement disorder with no known cure. Its characteristic motor symptoms are primarily caused by the progressive loss of midbrain dopaminergic neurons. Although studies have shown that various environmental and genetic factors both contribute to the development of the disease, the underlying mechanisms remain unknown. Here we use powerful invertebrate model organisms, fruit flies and nematode worms, and identify a new gene required for the survival of dopaminergic neurons. We show that homologs of the p48/ptf1-a gene in both flies and worms are expressed in dopaminergic neurons and mutations in p48 increase the susceptibility of dopaminergic neuron death when animals are under oxidative stress. Importantly, genetic variations in p48 in humans have been detected in the sporadic Parkinson's disease patients, indicating the possibility that similar mechanism might play a role in the death of dopaminergic neurons in humans. Oxidative stress has been regarded as a major pathogenic factor for Parkinson's disease. Our results add evidence to the link between oxidative stress and neurodegeneration, and suggest that p48 mutant flies and worms can be used to study mechanisms of neurodegeneration in Parkinson's disease.

Are delta-aminolevulinate dehydratase inhibition and metal concentrations additional factors for the age-related cognitive decline?

Aging is often accompanied by cognitive impairments and influenced by oxidative status and chemical imbalances. Thus, this study was conducted to examine whether age-related cognitive deficit is associated with oxidative damage, especially with inhibition of the enzyme delta-aminolevulinate dehydratase (ALA-D), as well as to verify the influence of some metals in the enzyme activity and cognitive performance. Blood ALA-D activity, essential (Fe, Zn, Cu, Se) and non-essential metals (Pb, Cd, Hg, As, Cr, Ni, V) were measured in 50 elderly and 20 healthy young subjects. Cognitive function was assessed by tests from Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) battery and other. The elderly group presented decreased ALA-D activity compared to the young group. The index of ALA-D reactivation was similar to both study groups, but negatively associated with metals. The mean levels of essential metals were within the reference values, while the most toxic metals were above them in both groups. Cognitive function impairments were observed in elderly group and were associated with decreased ALA-D activity, with lower levels of Se and higher levels of toxic metals (Hg and V). Results suggest that the reduced ALA-D activity in elderly can be an additional factor involved in cognitive decline, since its inhibition throughout life could lead to accumulation of the neurotoxic compound ALA. Toxic metals were found to contribute to cognitive decline and also to influence ALA-D reactivation.

The roles of biomarkers of oxidative stress and antioxidant in Alzheimer's disease: a systematic review

Purpose. Oxidative stress plays an important role in the pathogenesis of Alzheimer's disease (AD). This paper aims to examine whether biomarkers of oxidative stress and antioxidants could be useful biomarkers in AD, which might form the bases of future clinical studies. Methods. PubMed, SCOPUS, and Web of Science were systematically queried to obtain studies with available data regarding markers of oxidative stress and antioxidants from subjects with AD. Results and Conclusion. Although most studies show elevated serum markers of lipid peroxidation in AD, there is no sufficient evidence to justify the routine use of biomarkers as predictors of severity or outcome in AD.

Targeting aldehyde dehydrogenase 2: new therapeutic opportunities

A family of detoxifying enzymes called aldehyde dehydrogenases (ALDHs) has been a subject of recent interest, as its role in detoxifying aldehydes that accumulate through metabolism and to which we are exposed from the environment has been elucidated. Although the human genome has 19 ALDH genes, one ALDH emerges as a particularly important enzyme in a variety of human pathologies. This ALDH, ALDH2, is located in the mitochondrial matrix with much known about its role in ethanol metabolism. Less known is a new body of research to be discussed in this review, suggesting that ALDH2 dysfunction may contribute to a variety of human diseases including cardiovascular diseases, diabetes, neurodegenerative diseases, stroke, and cancer. Recent studies suggest that ALDH2 dysfunction is also associated with Fanconi anemia, pain, osteoporosis, and the process of aging. Furthermore, an ALDH2 inactivating mutation (termed ALDH2*2) is the most common single point mutation in humans, and epidemiological studies suggest a correlation between this inactivating mutation and increased propensity for common human pathologies. These data together with studies in animal models and the use of new pharmacological tools that activate ALDH2 depict a new picture related to ALDH2 as a critical health-promoting enzyme.

Alzheimer disease and cognitive impairment associated with diabetes mellitus type 2: associations and a hypothesis

INTRODUCTION

Epidemiological studies have demonstrated that patients with diabetes mellitus have an increased risk of developing Alzheimer disease, but the relationship between the 2 entities is not clear.

DEVELOPMENT

Both diseases exhibit similar metabolic abnormalities: disordered glucose metabolism, abnormal insulin receptor signalling and insulin resistance, oxidative stress, and structural abnormalities in proteins and β-amyloid deposits. Different hypotheses have emerged from experimental work in the last two decades. One of the most comprehensive relates the microvascular damage in diabetic polyneuritis with the central nervous system changes occurring in Alzheimer disease. Another hypothesis considers that cognitive impairment in both diabetes and Alzheimer disease is linked to a state of systemic oxidative stress. Recently, attenuation of cognitive impairment and normalisation of values in biochemical markers for oxidative stress were found in patients with Alzheimer disease and concomitant diabetes. Antidiabetic drugs may have a beneficial effect on glycolysis and its end products, and on other metabolic alterations.

CONCLUSIONS

Diabetic patients are at increased risk for developing Alzheimer disease, but paradoxically, their biochemical alterations and cognitive impairment are less pronounced than in groups of dementia patients without diabetes. A deeper understanding of interactions between the pathogenic processes of both entities may lead to new therapeutic strategies that would slow or halt the progression of impairment.

Atropisomerism of the Asn α radicals revealed by Ramachandran surface topology

C radicals are typically trigonal planar and thus achiral, regardless of whether they originate from a chiral or an achiral C-atom (e.g., C-H + (•)OH → C• + H2O). Oxidative stress could initiate radical formation in proteins when, for example, the H-atom is abstracted from the Cα-carbon of an amino acid residue. Electronic structure calculations show that such a radical remains achiral when formed from the achiral Gly, or the chiral but small Ala residues. However, when longer side-chain containing proteogenic amino acid residues are studied (e.g., Asn), they provide radicals of axis chirality, which in turn leads to atropisomerism observed for the first time for peptides. The two enantiomeric extended backbone structures, •βL and •βD, interconvert via a pair of enantiotopic reaction paths, monitored on a 4D Ramachandran surface, with two distinct transition states of very different Gibbs-free energies: 37.4 and 67.7 kJ/mol, respectively. This discovery requires the reassessment of our understanding on radical formation and their conformational and stereochemical behavior. Furthermore, the atropisomerism of proteogenic amino acid residues should affect our understanding on radicals in biological systems and, thus, reframes the role of the D-residues as markers of molecular aging.

Blood markers of oxidative stress in Alzheimer's disease

Alzheimer′s disease (AD) represents a highly common form of dementia, but can be diagnosed in the earlier stages before dementia onset. Early diagnosis is crucial for successful therapeutic intervention. The introduction of new diagnostic biomarkers for AD is aimed at detecting underlying brain pathology. These biomarkers reflect structural or biochemical changes related to AD. Examination of cerebrospinal fluid has many drawbacks; therefore, the search for sensitive and specific blood markers is ongoing. Investigation is mainly focused on upstream processes, among which oxidative stress in the brain is of particular interest. Products of oxidative stress may diffuse into the blood and evaluating them can contribute to diagnosis of AD. However, results of blood oxidative stress markers are not consistent among various studies, as documented in this review. To find a specific biochemical marker for AD, we should concentrate on specific metabolic products formed in the brain. Specific fluorescent intermediates of brain lipid peroxidation may represent such candidates as the composition of brain phospholipids is unique. They are small lipophilic molecules and can diffuse into the blood stream, where they can then be detected. We propose that these fluorescent products are potential candidates for blood biomarkers of AD.

Type 2 diabetes and/or its treatment leads to less cognitive impairment in Alzheimer's disease patients

AIM

To evaluate the cognitive performance of a homogeneous population of Alzheimer's disease (AD), non-demented Type 2 Diabetes Mellitus (DIAB), demented with concomitant diseases (AD+DIAB) and healthy control subjects. AD is a progressive dementia disorder characterized clinically by impairment of memory, cognition and behavior. Recently, a major research interest in AD has been placed on early evaluation. Diabetes is one of the clinical conditions that represent the greatest risk of developing oxidative stress and dementia. Glucose overload, leading to the development of impaired-induced insulin secretion in DIAB and has been suggested to slow or deter AD pathogenesis.

METHODS

The degree of cognitive impairment was determined on the Alzheimer Disease Assessment Scale-Cognitive (ADAS-Cog) and the Folstein's Mini Mental State Examination (MMSE); the severity of dementia was quantified applying the Clinical Dementia Rating (CDR) test; the Hamilton test was employed to evaluate depressive conditions; the final population studied was 101 subjects.

RESULTS

The cognitive deterioration is statistically significantly lower (p<0.05) in AD+DIAB patients as compared with AD patients.

CONCLUSIONS

In this longitudinal study the superimposed diabetic condition was associated with a lower rate of cognitive decline, while diabetic non-demented patients and controls present normal scores.

Altered serum iron and copper homeostasis predicts cognitive decline in mild cognitive impairment

Alzheimer's disease (AD) brain is marked by severe neuronal death which has been partly attributed to increased oxidative stress. The pathophysiology accounting for this free radical injury is not well-delineated at this point, but one hypothesis is that a derangement in transition metal metabolism contributes to the process. We tested the hypothesis that peripheral derangement of transition metal metabolism is present early in the dementing process. We analyzed non-heme iron and copper levels in serum from subjects with normal cognition, mild cognitive impairment, and early stage senile dementia and followed these subjects over 5 years. An increase in the ratio of serum copper to non-heme iron levels predicted which subjects with mild cognitive impairment would progress to dementia versus those that would remain cognitively stable. This increase did not correlate with changes in expression of iron regulatory protein 2 or selected downstream targets in peripheral lymphocytes. A cDNA-based microarray (IronChip) containing genes relevant to iron and copper metabolism was used to assess transition metal metabolism in circulating lymphocytes from cognitively normal and demented subjects. No gene was identified as being dysregulated more than 2-fold, and verification using quantitative RT-PCR demonstrated no significant changes in expression for ALAS2, FOS, and CTR1. The increased ratio of serum copper to serum iron prior to dementia has potential as a biomarker for cognitive decline and mirrors other changes in serum previously reported by others, but iron and copper metabolism pathways appear to be broadly unaffected in peripheral blood in AD.

Towards a unifying, systems biology understanding of large-scale cellular death and destruction caused by poorly liganded iron: Parkinson's, Huntington's, Alzheimer's, prions, bactericides, chemical toxicology and others as examples

Exposure to a variety of toxins and/or infectious agents leads to disease, degeneration and death, often characterised by circumstances in which cells or tissues do not merely die and cease to function but may be more or less entirely obliterated. It is then legitimate to ask the question as to whether, despite the many kinds of agent involved, there may be at least some unifying mechanisms of such cell death and destruction. I summarise the evidence that in a great many cases, one underlying mechanism, providing major stresses of this type, entails continuing and autocatalytic production (based on positive feedback mechanisms) of hydroxyl radicals via Fenton chemistry involving poorly liganded iron, leading to cell death via apoptosis (probably including via pathways induced by changes in the NF-κB system). While every pathway is in some sense connected to every other one, I highlight the literature evidence suggesting that the degenerative effects of many diseases and toxicological insults converge on iron dysregulation. This highlights specifically the role of iron metabolism, and the detailed speciation of iron, in chemical and other toxicology, and has significant implications for the use of iron chelating substances (probably in partnership with appropriate anti-oxidants) as nutritional or therapeutic agents in inhibiting both the progression of these mainly degenerative diseases and the sequelae of both chronic and acute toxin exposure. The complexity of biochemical networks, especially those involving autocatalytic behaviour and positive feedbacks, means that multiple interventions (e.g. of iron chelators plus antioxidants) are likely to prove most effective. A variety of systems biology approaches, that I summarise, can predict both the mechanisms involved in these cell death pathways and the optimal sites of action for nutritional or pharmacological interventions.

Non-enzymatic antioxidant capacity assays: Limitations of use in biomedicine

The 'Total antioxidant capacity' (TAC) is a parameter frequently used for characterization of food products and of the antioxidant status of the body. This mini-review shows shortcomings of TAC assays and points of concern that should be considered when performing and interpreting results of such assays. The term TAC is not optimal since the assay measures only part of antioxidant capacity, usually excluding enzymatic activities. Antioxidant and oxidant-regenerating enzymes in blood cells and the blood vessel wall have a profound impact on the antioxidant properties of blood plasma, which is not reflected in the in vitro assays of isolated plasma. The term 'Non-enzymatic antioxidant capacity' (NEAC) is suggested as more relevant than TAC. NEAC is estimated by various methods, which yield different values and results obtained using different methods do not always show satisfactory correlation. One reason for the discrepancy of results is the use of different oxidants in NEAC assays. The use of hydroxyl radical as the oxidant is not recommended in view of the high and non-specific reactivity of this species.

Brain mitochondrial dysfunction in aging, neurodegeneration, and Parkinson's disease

Brain senescence and neurodegeneration occur with a mitochondrial dysfunction characterized by impaired electron transfer and by oxidative damage. Brain mitochondria of old animals show decreased rates of electron transfer in complexes I and IV, decreased membrane potential, increased content of the oxidation products of phospholipids and proteins and increased size and fragility. This impairment, with complex I inactivation and oxidative damage, is named “complex I syndrome” and is recognized as characteristic of mammalian brain aging and of neurodegenerative diseases. Mitochondrial dysfunction is more marked in brain areas as rat hippocampus and frontal cortex, in human cortex in Parkinson's disease and dementia with Lewy bodies, and in substantia nigra in Parkinson's disease. The molecular mechanisms involved in complex I inactivation include the synergistic inactivations produced by ONOO− mediated reactions, by reactions with free radical intermediates of lipid peroxidation and by amine–aldehyde adduction reactions. The accumulation of oxidation products prompts the idea of antioxidant therapies. High doses of vitamin E produce a significant protection of complex I activity and mitochondrial function in rats and mice, and with improvement of neurological functions and increased median life span in mice. Mitochondria-targeted antioxidants, as the Skulachev cations covalently attached to vitamin E, ubiquinone and PBN and the SS tetrapeptides, are negatively charged and accumulate in mitochondria where they exert their antioxidant effects. Activation of the cellular mechanisms that regulate mitochondrial biogenesis is another potential therapeutic strategy, since the process generates organelles devoid of oxidation products and with full enzymatic activity and capacity for ATP production.

Oxidative stress and cognitive longevity

OBJECTIVE

The potential relation between metabolic activity within the central nervous system and retention of cognitive functioning capacity was assessed.

METHODS

A detailed literature review was conducted and summarized.

RESULTS

A large body of scientific evidence describes the interactions among cognitive activity, oxidative stress, neurodegeneration, neuroprotection, cognitive aging, and retention of cognitive functioning ability.

CONCLUSION

Maintenance of redox balance within the central nervous system can forestall cognitive decline and promote cognitive longevity.