Redox metals and neurodegenerative disease

Bioinformatics and System Biology Techniques to Determine Biomolecular Signatures and Pathways of Prion Disorder

Prion disorder (PD) is caused by misfolding and the formation of clumps of proteins in the brain, notably Prion proteins resulting in a steady decrease in brain function. Early detection of PD is difficult due to its unpredictable nature, and diagnosis is limited regarding specificity and sensitivity. Considering the uncertainties, the current study used network-based integrative system biology approaches to reveal promising molecular biomarkers and therapeutic targets for PD. In this study, brain transcriptomics gene expression microarray datasets (GSE160208 and GSE124571) of human PD were evaluated and 35 differentially expressed genes (DEGs) were identified. By employing network-based protein-protein interaction (PPI) analysis on these DEGs, 10 central hub proteins, including SPP1, FKBP5, HPRT1, CDKN1A, BAG3, HSPB1, SYK, TNFRSF1A, PTPN6, and CD44, were identified. Employing bioinformatics approaches, a variety of transcription factors (EGR1, SSRP1, POLR2A, TARDP, and NR2F1) and miRNAs (hsa-mir-8485, hsa-mir-148b-3p, hsa-mir-4295, hsa-mir-26b-5p, and hsa-mir-16-5p) were predicted. EGR1 was found as the most imperative transcription factor (TF), and hsa-mir-16-5p and hsa-mir-148b-3p were found as the most crucial miRNAs targeted in PD. Finally, resveratrol and hypochlorous acid were predicted as possible therapeutic drugs for PD. This study could be helpful in better understanding of molecular systems and prospective pharmacological targets for developing effective PD treatments.

Protocols for Understanding the Redox Behavior of Copper-Containing Systems

Suitability of single-reference density functional theory (DFT) methods for the calculation of redox potentials of copper-containing macrocycle complexes was confirmed by the use of T ₁ diagnostics along with a verification of negligible spin contamination or wave function instability. When examining the effect of improvement in the cc-pVnZ basis set series on calculated redox potentials, the results readily converged at the cc-pVTZ level. The all-electron Def2-TZVPP basis set is shown to be a suitable choice of a basis set for the calculation of redox potentials when utilizing a cc-pVTZ geometry. The best-performing model chemistries are determined to be the M06/polarizable continuum model (PCM); therefore, a scheme for redox potential calculations of copper macrocycles using either M06/cc-pVTZ with PCM solvation is proposed to reliably reproduce experimental trends.

Nanoparticle-based colorimetric sensors to detect neurodegenerative disease biomarkers

Neurodegenerative disorders (NDDs) are progressive, incurable health conditions that primarily affect brain cells, and result in loss of brain mass and impaired function. Current sensing technologies for NDD detection are limited by high cost, long sample preparation, and/or require skilled personnel. To overcome these limitations, optical sensors, specifically colorimetric sensors, have garnered increasing attention towards the development of a cost-effective, simple, and rapid alternative approach. In this review, we evaluate colorimetric sensing strategies of NDD biomarkers (e.g. proteins, neurotransmitters, bio-thiols, and sulfide), address the limitations and challenges of optical sensor technologies, and provide our outlook on the future of this field.

X1INH, an improved next-generation affinity-optimized hydrazonic ligand, attenuates abnormal copper(I)/copper(II)-α-Syn interactions and affects protein aggregation in a cellular model of synucleinopathy

Although normal aging presents an accumulation of copper and iron in the brain, this becomes more relevant in neurodegeneration. α-Synuclein (α-Syn) misfolding has long been linked with the development of Parkinson's disease (PD). Copper binding promotes aggregation of α-Syn, as well as generalized oxidative stress. In this sense, the use of therapies that target metal dyshomeostasis has been in focus in the past years. Metal-Protein Attenuating Compounds (MPACs) are moderate chelators that aim at disrupting specific, abnormal metal-protein interactions. Our research group has now established that N-acylhydrazones compose a set of truly encouraging MPACs for the bioinorganic management of metal-enhanced aggregopathies. In the present work, a novel ligand, namely 1-methyl-1H-imidazole-2-carboxaldehyde isonicotinoyl hydrazone (X1INH), is reported. We describe solution studies on the interaction and affinity of this compound for copper(ii) ions showing that a fine tuning of metal-affinity was achieved. A series of in vitro biophysical NMR experiments were performed in order to assess the X1INH ability to compete with α-Syn monomers for the binding of both copper(i) and copper(ii) ions, which are central in PD pathology. A preference for copper(i) has been observed. X1INH is less toxic to human neuroglioma (H4) cells in comparison to structure-related compounds. Finally, we show that treatment with X1INH results in a higher number of smaller, less compact inclusions in a well-established model of α-Syn aggregation. Thus, X1INH constitutes a promising MPAC for the treatment of Parkinson's disease.

The Association between Serum Oxidative Stress Indexes and Pathogenesis of Parkinson's Disease in the Northwest of Iran

Background:

Parkinson’s disease (PD) is a prevalent neurodegenerative disorder. Oxidative stress is a main modulator in the advancement of PD. This investigation aimed to evaluate the relations between serum trace elements, vitamin C, ferritin, transferrin, Nitrite Oxide (NOx) and Peroxynitrite (PrN) concentrations and clinical parameters in patients with PD.

Methods:

Serum concentrations of variables were measured in 75 PD patients and 75 healthy subjects from Imam Reza Hospital, Tabriz University of Medical Sciences, Tabriz, Iran between Feb 2016 and Sep 2018. Receiver Operating Characteristic (ROC) analysis was performed to examine incremental diagnostic value of vitamin C, NOx, and PrN in the study groups.

Results:

Mean serum NOx (35.81±5.16 vs. 11.27±3.59 mol/L, P<0.001) and PrN (15.78±4.23 vs. 9.62±4.57 mol/L, P= 0.004) were markedly higher in patient group versus healthy individuals. Significant differences were also observed in the serum levels of vitamin C (P<0.001), copper (Cu) (P<0.001), Iron (Fe) (P=0.003), and Zinc (Zn) (P<0.001) between patients with PD and healthy subjects. Nevertheless, the serum levels of Se (P=0.515), ferritin (P=0.103), and transferrin (P=0.372) were not statistically significant between the study groups. ROC analysis has revealed a diagnostic ability of serum vitamin C levels for PD with an area under ROC curve of ≥0.7 (P<0.05) and relatively high sensitivity and specificity.

Conclusion:

Serum levels of NOx and PrN are significantly higher in patients with PD. In additions, serum vitamin C levels have a diagnostic value as a biomarker. Further studies are required with larger sample size to provide more detailed information about the cognitive profile of participants and the outcome measures.

Polyphenols as Potential Metal Chelation Compounds Against Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disease affecting more than 50 million people worldwide. The pathology of this multifactorial disease is primarily characterized by the formation of amyloid-β (Aβ) aggregates; however, other etiological factors including metal dyshomeostasis, specifically copper (Cu), zinc (Zn), and iron (Fe), play critical role in disease progression. Because these transition metal ions are important for cellular function, their imbalance can cause oxidative stress that leads to cellular death and eventual cognitive decay. Importantly, these transition metal ions can interact with the amyloid-β protein precursor (AβPP) and Aβ42 peptide, affecting Aβ aggregation and increasing its neurotoxicity. Considering how metal dyshomeostasis may substantially contribute to AD, this review discusses polyphenols and the underlying chemical principles that may enable them to act as natural chelators. Furthermore, polyphenols have various therapeutic effects, including antioxidant activity, metal chelation, mitochondrial function, and anti-amyloidogenic activity. These combined therapeutic effects of polyphenols make them strong candidates for a moderate chelation-based therapy for AD.

Study of Occupational Chromium, Iron, and Nickel Exposure and Amyotrophic Lateral Sclerosis in Denmark

Studies of occupational metal exposures and amyotrophic lateral sclerosis (ALS) have focused primarily on known neurotoxicants, including lead, mercury, selenium, and cadmium. However, these exposures are often co-occurring with other lesser studied metals. We conducted a population-based case-control study with the aim of assessing associations between occupational chromium, iron, and nickel exposures and risk of ALS. We identified ALS cases in Denmark from 1982 through 2013 from the Danish National Patient Registry and matched them to 100 controls based on birth year and sex. Cumulative metal exposures were estimated using job exposure matrices applied to occupational history from the Danish Pension Fund. Although mutually adjusted odds of ALS were higher in men with chromium exposures in the third quartile (aOR = 1.24; 95% CI 0.91, 1.69) and fourth quartile (aOR = 1.19; 95% CI: 0.80, 1.76) compared to those with no exposure, differences did not reach statistical significance. We also observed higher odds of ALS in women with nickel exposures in the third quartile (aOR = 2.21; 95% CI: 1.14, 4.28), but not for the fourth quartile (aOR = 0.61; 95% CI: 0.23, 1.64). Our findings do not suggest associations between occupational exposures to these metals and ALS. However, unavoidable non-differential misclassification from the use of JEMs may have masked truly increased risk.

Dual-probe (colorimetric and fluorometric) detection of ferritin using antibody-modified gold@carbon dot nanoconjugates

A dual-mode assay is described for immunological determination of the anemia biomarker ferritin. It is based on the use of a gold@carbon dot (Au@CD) nanoconjugate as a colorimetric and fluorescent probe. Au@CD is hydrophilic, easily surface modified and stable in aqueous solution. The Au@CD have a red color with blue-green fluorescence and were modified with antibody against ferritin. This allows bi-modal detection of ferritin. Assays can be performed in phosphate buffer and were also analyzed in (Bovine Serum Albumin) BSA and (Fetal Bovine Serum) FBS. Detection is based on antigen-antibody interaction underlying the classical sandwich model. Response to ferritin can be detected by spectrophotometry (at 570 nm) or fluorescence (at excitation/emission maxima of 354/454 nm). Under optimal conditions, the assay has a linear response in the 1 to 120 ngmL^-1 ferritin concentration range and detection limits of 20 ng (colorimetrically) and 64 ng (fluorometrically). Graphical abstract Schematic representation of the function of the designed nanoprobe. The Au@CD nanoconjugates are functionalized with ferritin antibody in the initial step which specifically interacts with ferritin molecules leading to aggregation and subsequent changes in the optical and fluorescence signals.

Species fractionation in a case-control study concerning Parkinson's disease: Cu-amino acids discriminate CSF of PD from controls

BACKGROUND

Parkinson's disease is affecting about 1% of the population above 65 years. Improvements in medicine support prolonged lifetime which increases the total concentration of humans affected by the disease. It is suggested that occupational and environmental exposure to metals like iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) can influence the risk for Parkinson's disease. These metals play a key role as cofactors in many enzymes and proteins.

METHODS

In this case-control study, we investigated the Mn-, Fe-, Cu- and Zn-species in cerebrospinal fluid (CSF) by size-exclusion chromatography hyphenated to inductively coupled plasma mass spectrometry (SEC-ICP-MS) and the total concentration of these metals by inductively coupled plasma sector field mass spectrometry (ICP-sf-MS).

RESULTS

The investigation of total metal concentration and speciation provided only minor changes, but it produced strong significance for a number of ratios. The analysis revealed a strong change in the ratio between total concentration of Fe and the amino acid-fraction of Cu. This could be observed when analyzing both the respective element concentrations of the fraction (which also depends on individual variation of the total element concentration) as well as when being expressed as percentage of total concentration (normalization) which more clearly shows changes of distribution pattern independent of individual variation of total element concentrations.

CONCLUSION

Speciation analysis, therefore, is a powerful technique to investigate changes in a case-control study where ratios of different species play an important role.

Evaluation of Iron Deficiency Anemia Frequency as a Risk Factor in Glaucoma

Purpose

Iron deficiency anemia is an important public health problem. Also it is considered to be a risk factor for many diseases. The study demonstrates the iron deficiency anemia frequency in glaucoma patients and compares with the normal subjects. We aimed to determine the iron deficiency anemia frequency in glaucoma patients.

Methods

Prospective, controlled study in a single university hospital setting. A total of 130 normal subjects (Group 1) and 131 glaucoma patients (Group 2) were included. The erythrocytes parameters, hemoglobin, red blood cell, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, and red blood cell distribution width, and iron status indicators, Fe (iron), total iron binding capacity, and ferritin of the cases, in normal subjects and glaucoma patients were compared.

Results

There was no statistically significant difference for the erythrocyte parameters between the groups (p≥0.05). The number of the patients with iron deficiency anemia in both groups was similar. No statistically significant difference was found in the comparison of erythrocyte parameters and iron status indicators values according to the number of antiglaucomatous agents and visual field changes according to the presence of anemia in Group 2 (p≥0.05). A statistically significant difference was found only in MCH when the erythrocyte parameters and iron status indicators values of the cases in glaucoma patients were compared with the glaucoma duration (p<0.05).

Conclusion

The iron deficiency anemia frequency was like the normal population in glaucoma patients.

Copper or/and arsenic induce oxidative stress-cascaded, nuclear factor kappa B-dependent inflammation and immune imbalance, trigging heat shock response in the kidney of chicken

Excessive amount of copper (Cu) and inorganic arsenic (iAs) coexists in drinking water in many regions, this is associated with high risk of nephropathy, defined as chronic structural and functional disorders of the kidney. However, the underlying mechanisms are not well understood. In this study, a total of 72 day-old Hy-line chickens were exposed to 300 mg/kg copper sulphate or/and 30 mg/kg arsenic trioxide for 12 weeks. Indicators of oxidative stress, inflammation and heat shock proteins (HSPs) production were analyzed in kidney. The results showed that, when the toxicant was administrated alone, there is an antagonism between redox homeostasis during the first 4 weeks, which follows a collapse of antioxidant system manifested by damaged biomembrane structure. What's worse, oxidative damage-cascaded histopathological lesions were accompanied by increases of proinflammatory mediators and an imbalance of "Th1/Th2 drift" (Th, helper T cell) regulated by nuclear factor kappa B (NF-κB). Simultaneously, intense heat shock response went with the organism. The above-mentioned renal lesions and indicators changes were time-dependent, more complex and deteriorated effects were observed in Cu/iAs combined groups compared with the others. This study supports Cu and iAs have a synergistic type on the nephro-toxicological process additively. In conclusion, oxidative stress and inflammatory induced by Cu or/and iAs are potential mechanisms in their nephrotoxicity, increased heat shock response may play a renoprotection function in tissues damage.

Self-assembling peptide and protein amyloids: from structure to tailored function in nanotechnology

Self-assembled peptide and protein amyloid nanostructures have traditionally been considered only as pathological aggregates implicated in human neurodegenerative diseases. In more recent times, these nanostructures have found interesting applications as advanced materials in biomedicine, tissue engineering, renewable energy, environmental science, nanotechnology and material science, to name only a few fields. In all these applications, the final function depends on: (i) the specific mechanisms of protein aggregation, (ii) the hierarchical structure of the protein and peptide amyloids from the atomistic to mesoscopic length scales and (iii) the physical properties of the amyloids in the context of their surrounding environment (biological or artificial). In this review, we will discuss recent progress made in the field of functional and artificial amyloids and highlight connections between protein/peptide folding, unfolding and aggregation mechanisms, with the resulting amyloid structure and functionality. We also highlight current advances in the design and synthesis of amyloid-based biological and functional materials and identify new potential fields in which amyloid-based structures promise new breakthroughs.

Neurotoxic effects of subchronic intratracheal Mn nanoparticle exposure alone and in combination with other welding fume metals in rats

Manganese (Mn) is a toxic heavy metal exposing workers in various occupational settings and causing, among others, nervous system damage. Metal fumes of welding, a typical source of Mn exposure, contain a complex mixture of metal oxides partly in nanoparticle form. As toxic effects of complex substances cannot be sufficiently understood by examining its components separately, general toxicity and functional neurotoxicity of a main pathogenic welding fume metal, Mn, was examined alone and combined with iron (Fe) and chromium (Cr), also frequently found in fumes. Oxide nanoparticles of Mn, Mn + Fe, Mn + Cr and the triple combination were applied, in aqueous suspension, to the trachea of young adult Wistar rats for 4 weeks. The decrease of body weight gain during treatment, caused by Mn, was counteracted by Fe, but not Cr. At the end of treatment, spontaneous and evoked cortical electrical activity was recorded. Mn caused a shift to higher frequencies, and lengthened evoked potential latency, which were also strongly diminished by co-application of Fe only. The interaction of the metals seen in body weight gain and cortical activity were not related to the measured blood and brain metal levels. Fe might have initiated protective, e.g. antioxidant, mechanisms with a more general effect.

Trace Mineral Overload Induced Hepatic Oxidative Damage and Apoptosis in Pigs with Long-Term High-Level Dietary Mineral Exposure

The present study investigated the effects of dietary trace mineral (Cu, Fe, Mn, and Zn) supplemental strategies on liver oxidative stress, endoplasmic reticulum stress, inflammation, and apoptosis of pigs. A total of 96 Duroc × Landrace × Yorkshire (DLY) piglets were randomly divided into four groups: considered or not considered the trace mineral concentrations in basal diet, and then added to the requirements proposed by NRC (2012) (+B/NR or -B/NR); and considered or not considered the basal diet's trace mineral concentrations and then added to the level of commercial trace mineral supplement (+B/PL or -B/PL). Pigs were fed from 6.5 to 115 kg. Compared with +B/NR diets, -B/PL diets increased serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) concentrations (P < 0.05), resulted in high levels of Fe, Cu, Mn, and Zn accumulation in liver (P < 0.05), as well as led to hepatic oxidative damage with the high concentrations of thiobarbituric acid reactive substance (TBARS), protein carbonylation (PCO), and 8-hydroxyguanine (8-OHG) in liver (P < 0.05). Furthermore, pigs fed -B/PL diets increased CCAAT/enhancer-binding protein homologous protein (CHOP), eukaryotic initiation factor-2α (eIF-2a), interleukin-6(IL-6), B-cell lymphoma leukemia-2-associated X protein (Bax), and caspase-3, caspase-8, and caspase-9 gene expression (P < 0.05) in liver. -B/PL diets also up-regulated hepatic mRNA expression of phosphoenolpyruvate carboxykinase1 (PEPCK1), glucose-6-phosphatase (G6PC), acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS) (P < 0.05) and down-regulated hormone-sensitive lipase (HSL) mRNA expression (P < 0.05) when compared with those of the + B/NR diet group. Taken together, the results indicated that long-term dietary mineral exposure with the commercial supplement level could cause harm to the structure and metabolic function of liver in pigs.

Aggregation induced emission enhancement and growth of naphthalimide nanoribbons via J-aggregation: insight into disaggregation induced unfolding and detection of ferritin at the nanomolar level

A core substituted naphthalimide AIEEgen displays unusual nanoribbon growth in aqueous media with ultra-sensitivity towards non-heme protein ferritin at physiological conditions.

Protective Effects of Lactobacillus plantarum CCFM8246 against Copper Toxicity in Mice

Lactobacillus plantarum CCFM8246, which has a relatively strong copper binding capacity and tolerance to copper ions, was obtained by screening from 16 lactic acid bacteria in vitro. The selected strain was then applied to a mouse model to evaluate its protective function against copper intoxication in vivo. The experimental mice were divided into an intervention group and a therapy group; mice in the intervention group received co-administration of CCFM8246 and a copper ion solution by gavage, while mice in the therapy group were treated with CCFM8246 after 4 weeks of copper exposure. In both two groups, mice treated with copper alone and that treated with neither CCFM8246 nor copper served as positive and negative controls, respectively. At the end of the experimental period, the copper content in feces and tissues, the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum, and oxidation stress indices in liver and kidney tissue were determined. Learning and memory ability was evaluated by Morris water maze experiments. The results indicated that treatment with CCFM8246 significantly increased the copper content in feces to promote copper excretion, reduce the accumulation of copper in tissues, reverse oxidative stress induced by copper exposure, recover the ALT and AST in serum and improve the spatial memory of mice.

The possible mechanism of Parkinson's disease progressive damage and the preventive effect of GM1 in the rat model induced by 6-hydroxydopamine

The progressive pathogenesis and prevention of Parkinson's disease (PD) remains unknown at present. Therefore, the present study aimed to investigate the possible progressive pathogenesis and prevention of PD. Our study investigated the content of glutamate, mitochondria calcium, calmodulin, malonaldehyde and trace elements in striatum, cerebral cortex and hippocampus tissues; and the expression of bcl-2, bax and neuronal nitric oxide synthase (nNOS) in substantia nigra and striatum; and the change of apomorphine induced rotation behavior; and the treatmental effect of monosialotetrahexosylganglioside (GM1) intraperitoneal administration for 14 days in a PD rat model induced by 6-hydroxydopamine. The results revealed that the content of glutamate significantly decreased, and that of mitochondria calcium, calmodulin, malonaldehyde and ferrum significantly increased in striatum, cerebral cortex and hippocampus tissues; the content of magnesium significantly decreased, and that of cuprum and zinc significantly increased in cerebral cortex; the expression of bcl-2 significantly decreased, and that of bax and nNOS significantly increased in substantia nigra and striatum in PD rat. GM1 can partially improve the apomorphine induced rotation behavior and changes of glutamate, mitochondria calcium, calmodulin content in striatum of PD rat. Data suggested that dysfunction of excitatory amino acids neurotransmitter, calcium homeostasis disorder, abnormal metabolism of oxygen free radicals, abnormal trace elements distribution and/or deposition and excessive apoptosis participated in the progressive process of PD, and that GM1 could partially prevent the progressive damage.

QM/MM molecular dynamics studies of metal binding proteins

Mixed quantum-classical (quantum mechanical/molecular mechanical (QM/MM)) simulations have strongly contributed to providing insights into the understanding of several structural and mechanistic aspects of biological molecules. They played a particularly important role in metal binding proteins, where the electronic effects of transition metals have to be explicitly taken into account for the correct representation of the underlying biochemical process. In this review, after a brief description of the basic concepts of the QM/MM method, we provide an overview of its capabilities using selected examples taken from our work. Specifically, we will focus on heme peroxidases, metallo-β-lactamases, α-synuclein and ligase ribozymes to show how this approach is capable of describing the catalytic and/or structural role played by transition (Fe, Zn or Cu) and main group (Mg) metals. Applications will reveal how metal ions influence the formation and reduction of high redox intermediates in catalytic cycles and enhance drug metabolism, amyloidogenic aggregate formation and nucleic acid synthesis. In turn, it will become manifest that the protein frame directs and modulates the properties and reactivity of the metal ions.

Neuronal failure in Alzheimer's disease: a view through the oxidative stress looking-glass

Considerable debate and controversy surround the cause(s) of Alzheimer's disease (AD). To date, several theories have gained notoriety, however none is universally accepted. In this review, we provide evidence for the oxidative stress-induced AD cascade that posits aged mitochondria as the critical origin of neurodegeneration in AD.

Comparison of three competing dynamic force spectroscopy models to study binding forces of amyloid-β (1-42)

We performed single molecule dynamic force spectroscopy experiments to study the dimerization of two amyloid-β (1-42) peptides and compared three different theoretical models used to fit experimental data: Bell-Evans, Dudko-Hummer-Szabo, and Friddle-De Yoreo. Using these models we extracted values of the dissociation rate at zero force, k0, and height and the width of the energy barrier, ΔG and xβ. We show the importance of including the effect of the linker molecule. All three models corrected for the linker effect give comparable results for xβ and show more discrepancy for k0 and ΔG values, ΔG parameter correlates well between Dudko-Hummer-Szabo and Friddle-De Yoreo models but differs for the Bell-Evans model.

Atomic force microscopy to study molecular mechanisms of amyloid fibril formation and toxicity in Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disease characterized by dementia and memory loss for which no cure or effective prevention is currently available. Neurodegeneration in AD is linked to formation of amyloid plaques found in brain tissues of Alzheimer's patients during post-mortem examination. Amyloid plaques are composed of amyloid fibrils and small oligomers - insoluble protein aggregates. Although amyloid plaques are found on the neuronal cell surfaces, the mechanism of amyloid toxicity is still not well understood. Currently, it is believed that the cytotoxicity is a result of the nonspecific interaction of small soluble amyloid oligomers (rather than longer fibrils) with the plasma membrane. In recent years, nanotechnology has contributed significantly to understanding the structure and function of lipid membranes and to the study of the molecular mechanisms of membrane-associated diseases. We review the current state of research, including applications of the latest nanotechnology approaches, on the interaction of lipid membranes with the amyloid-β (Aβ) peptide in relation to amyloid toxicity. We discuss the interactions of Aβ with model lipid membranes with a focus to demonstrate that composition, charge and phase of the lipid membrane, as well as lipid domains and rafts, affect the binding of Aβ to the membrane and contribute to toxicity. Understanding the role of the lipid membrane in AD at the nanoscale and molecular level will contribute to the understanding of the molecular mechanism of amyloid toxicity and may aid into the development of novel preventive strategies to combat AD.

Toxicity of copper salts is dependent on solubility profile and cell type tested

Copper (Cu) is considered an essential metal for living organisms. However, disruption of Cu homeostasis is toxic and can lead to disorders such as Menkes and Wilson's diseases. The brain appears to be a vulnerable target organ. This study investigated the toxicity of Cu based on its solubility profile and cell type tested. Human A-172 (glioblastoma), SK-N-SH (neuroblastoma) and CCF-STTG1 (astrocytoma) cells were assessed after exposure to different concentrations (0.5-500μM) of copper sulfate (CuSO4) or copper (II) oxide (CuO). Since Cu is a redox active transition metal, we hypothesized that oxidative stress would be the main mechanism underlying cell toxicity. Therefore, cell viability was correlated with the extent of reactive oxygen species (ROS) formation. Cell viability decreased at the higher concentrations of the Cu salts and CuO was more toxic compared to CuSO4. The astrocytoma and glioblastoma cells were more vulnerable compared to the neuronal cells. Furthermore, it appears that oxidative stress only partially accounts for Cu-induced cell toxicity. Further studies are needed to better understand the unique susceptibility of glial cells and determine the physicochemical properties of insoluble Cu which accounts for its enhanced toxicity.

Nanoparticle delivery of transition-metal chelators to the brain: Oxidative stress will never see it coming!

The pathological lesions typical of Alzheimer disease (AD) are sites of significant and abnormal metal accumulation. Metal chelation therapy, therefore, provides a very attractive therapeutic measure for the neuronal deterioration of AD, though its institution suffers fundamental deficiencies. Namely, chelating agents, which bind to and remove excess transition metals from the body, must penetrate the blood-brain barrier to instill any real effect on the oxidative damages caused by the presence of the metals in the brain. Despite many advances in chelation administration, however, this vital requirement remains therapeutically out of reach: the most effective chelators-i.e., those that have high affinity and specificity for transition metals like iron and copper-are bulky and hydrophilic, making it difficult to reach their physiological place of action. Moreover, small, lipophilic chelators, which can pass through the brain's defensive wall, essentially suffer from their over-effectiveness. That is, they induce toxicity on proliferating cells by removing transition metals from vital RNA enzymes. Fortunately, research has provided a loophole. Nanoparticles, tiny, artificial or natural organic polymers, are capable of transporting metal chelating agents across the blood-brain barrier regardless of their size and hydrophilicity. The compounds can thereby sufficiently ameliorate the oxidative toxicity of excess metals in an AD brain without inducing any such toxicity themselves. We here discuss the current status of nanoparticle delivery systems as they relate to AD chelation therapy and elaborate on their mechanism of action. An exciting future for AD treatment lies ahead.

The antioxidant mechanisms underlying the aged garlic extract- and S-allylcysteine-induced protection

Aged garlic extract (AGE) is an odorless garlic preparation containing S-allylcysteine (SAC) as its most abundant compound. A large number of studies have demonstrated the antioxidant activity of AGE and SAC in both in vivo--in diverse experimental animal models associated to oxidative stress--and in vitro conditions--using several methods to scavenge reactive oxygen species or to induce oxidative damage. Derived from these experiments, the protective effects of AGE and SAC have been associated with the prevention or amelioration of oxidative stress. In this work, we reviewed different antioxidant mechanisms (scavenging of free radicals and prooxidant species, induction of antioxidant enzymes, activation of Nrf2 factor, inhibition of prooxidant enzymes, and chelating effects) involved in the protective actions of AGE and SAC, thereby emphasizing their potential use as therapeutic agents. In addition, we highlight the ability of SAC to activate Nrf2 factor--a master regulator of the cellular redox state. Here, we include original data showing the ability of SAC to activate Nrf2 factor in cerebral cortex. Therefore, we conclude that the therapeutic properties of these molecules comprise cellular and molecular mechanisms at different levels.

Metal chaperones: a holistic approach to the treatment of Alzheimer's disease

As evidence for the role of metal ion dysregulation in the pathogenesis of multiple CNS disorders grows, it has become important to more precisely identify and differentiate the biological effects of various pharmacological modulators of metal ion homeostasis. This is particularly evident in disorders such as Alzheimer's disease (AD), where the use of metal chaperones (that transport metals), as opposed to chelators (which exclude metals from biological interactions), may prove to be the first truly disease modifying approach for this condition. The purpose of this mini-review is to highlight the emerging notion that metal chaperones, such as PBT2 (Prana Biotechnology), modulate a variety of critical pathways affecting key aspects of the AD cascade to provide a more "holistic" approach to the treatment of this disease.

Lipid peroxidation in Alzheimer's disease: emphasis on metal-mediated neurotoxicity

Despite the crucial role of redox active metals like copper and iron in central biological reactions, their elevated levels are involved in the pathogenesis of Alzheimer's Disease (AD). Similarly reactive oxygen/nitrogen species (ROS/RNS) produced during normal metabolic activities, specifically oxidative phosphorylation of the cell, are scavenged by antioxidant enzymes like superoxide dismutase (SOD), catalase but impaired metabolic pathways tend to generate elevated levels of these ROS/RNS. Iron, copper, and zinc are some of the metals, which intensify this process and contribute for the pathogenesis of AD. This review summarizes the mechanism of ROS/RNS production and their role in lipid peroxidation. The factors, which make brain vulnerable for lipid peroxidation, have been discussed. It also focuses on possible treatment options and future directions.

Infectious prion protein alters manganese transport and neurotoxicity in a cell culture model of prion disease

Protein misfolding and aggregation are considered key features of many neurodegenerative diseases, but biochemical mechanisms underlying protein misfolding and the propagation of protein aggregates are not well understood. Prion disease is a classical neurodegenerative disorder resulting from the misfolding of endogenously expressed normal cellular prion protein (PrP(C)). Although the exact function of PrP(C) has not been fully elucidated, studies have suggested that it can function as a metal binding protein. Interestingly, increased brain manganese (Mn) levels have been reported in various prion diseases indicating divalent metals also may play a role in the disease process. Recently, we reported that PrP(C) protects against Mn-induced cytotoxicity in a neural cell culture model. To further understand the role of Mn in prion diseases, we examined Mn neurotoxicity in an infectious cell culture model of prion disease. Our results show CAD5 scrapie-infected cells were more resistant to Mn neurotoxicity as compared to uninfected cells (EC(50)=428.8 μM for CAD5 infected cells vs. 211.6 μM for uninfected cells). Additionally, treatment with 300 μM Mn in persistently infected CAD5 cells showed a reduction in mitochondrial impairment, caspase-3 activation, and DNA fragmentation when compared to uninfected cells. Scrapie-infected cells also showed significantly reduced Mn uptake as measured by inductively coupled plasma-mass spectrometry (ICP-MS), and altered expression of metal transporting proteins DMT1 and transferrin. Together, our data indicate that conversion of PrP to the pathogenic isoform enhances its ability to regulate Mn homeostasis, and suggest that understanding the interaction of metals with disease-specific proteins may provide further insight to protein aggregation in neurodegenerative diseases.

Fluorescent indicators based on BODIPY

This critical review covers the advances made using the 4-bora-3a,4a-diaza-s-indacene (BODIPY) scaffold as a fluorophore in the design, synthesis and application of fluorescent indicators for pH, metal ions, anions, biomolecules, reactive oxygen species, reactive nitrogen species, redox potential, chemical reactions and various physical phenomena. The sections of the review describing the criteria for rational design of fluorescent indicators and the mathematical expressions for analyzing spectrophotometric and fluorometric titrations are applicable to all fluorescent probes (206 references).

Mechanisms of brain iron transport: insight into neurodegeneration and CNS disorders

Trace metals such as iron, copper, zinc, manganese, and cobalt are essential cofactors for many cellular enzymes. Extensive research on iron, the most abundant transition metal in biology, has contributed to an increased understanding of the molecular machinery involved in maintaining its homeostasis in mammalian peripheral tissues. However, the cellular and intercellular iron transport mechanisms in the central nervous system (CNS) are still poorly understood. Accumulating evidence suggests that impaired iron metabolism is an initial cause of neurodegeneration, and several common genetic and sporadic neurodegenerative disorders have been proposed to be associated with dysregulated CNS iron homeostasis. This review aims to provide a summary of the molecular mechanisms of brain iron transport. Our discussion is focused on iron transport across endothelial cells of the blood-brain barrier and within the neuro- and glial-vascular units of the brain, with the aim of revealing novel therapeutic targets for neurodegenerative and CNS disorders.

The biochemical and cellular basis for nutraceutical strategies to attenuate neurodegeneration in Parkinson's disease

Future therapeutic intervention that could effectively decelerate the rate of degeneration within the substantia nigra pars compacta (SNc) could add years of mobility and reduce morbidity associated with Parkinson’s disease (PD). Neurodegenerative decline associated with PD is distinguished by extensive damage to SNc dopaminergic (DAergic) neurons and decay of the striatal tract. While genetic mutations or environmental toxins can precipitate pathology, progressive degenerative succession involves a gradual decline in DA neurotransmission/synaptic uptake, impaired oxidative glucose consumption, a rise in striatal lactate and chronic inflammation. Nutraceuticals play a fundamental role in energy metabolism and signaling transduction pathways that control neurotransmission and inflammation. However, the use of nutritional supplements to slow the progression of PD has met with considerable challenge and has thus far proven unsuccessful. This review re-examines precipitating factors and insults involved in PD and how nutraceuticals can affect each of these biological targets. Discussed are disease dynamics (Sections 1 and 2) and natural substances, vitamins and minerals that could impact disease processes (Section 3). Topics include nutritional influences on α-synuclein aggregation, ubiquitin proteasome function, mTOR signaling/lysosomal-autophagy, energy failure, faulty catecholamine trafficking, DA oxidation, synthesis of toxic DA-quinones, o-semiquinones, benzothiazolines, hyperhomocyseinemia, methylation, inflammation and irreversible oxidation of neuromelanin. In summary, it is clear that future research will be required to consider the multi-faceted nature of this disease and re-examine how and why the use of nutritional multi-vitamin-mineral and plant-based combinations could be used to slow the progression of PD, if possible.

Abnormal iron metabolism in fibroblasts from a patient with the neurodegenerative disease hereditary ferritinopathy

Background

Nucleotide duplications in exon 4 of the ferritin light polypeptide (FTL) gene cause the autosomal dominant neurodegenerative disease neuroferritinopathy or hereditary ferritinopathy (HF). Pathologic examination of patients with HF has shown abnormal ferritin and iron accumulation in neurons and glia in the central nervous system (CNS) as well as in cells of other organ systems, including skin fibroblasts. To gain some understanding on the molecular basis of HF, we characterized iron metabolism in primary cultures of human skin fibroblasts from an individual with the FTL c.497_498dupTC mutation.

Results

Compared to normal controls, HF fibroblasts showed abnormal iron metabolism consisting of increased levels of ferritin polypeptides, divalent metal transporter 1, basal iron content and reactive oxygen species, and decreased levels of transferrin receptor-1 and IRE-IRP binding activity.

Conclusions

Our data indicates that HF fibroblasts replicate the abnormal iron metabolism observed in the CNS of patients with HF. We propose that HF fibroblasts are a unique cellular model in which to study the role of abnormal iron metabolism in the pathogenesis of HF without artifacts derived from over-expression or lack of endogenous translational regulatory elements.

Nanotechnology in Neurosurgery

Clinical neurology and neurosurgery are two fields that face some of the most challenging and exciting problems remaining in medicine. Brain tumors, paralysis after trauma or stroke, and neurodegerative diseases are some of the many disorders for which effective therapies remain elusive. Nanotechnology seems poised to offer promising new solutions to some of these difficult problems. The latest advances in materials engineered at the nanoscale for applications relevant to the clinical neurosciences, such as medical imaging, nanotherapies for neurologic disease, nerve tissue engineering, and nanotechnological contributions to neuroelectrodes and brain-machine interface technology are reviewed. The primary classes of materials discussed include superparamagnetic iron oxide nanoparticles, gold nanoparticles, liposomes, carbon fullerenes, and carbon nanotubes. The potential of the field and the challenges that must be overcome for the current technology to become available clinically are highlighted.

Cadmium intoxication of pregnant rats and fetuses: interactions of copper supplementation

BACKGROUND AND AIMS

Cadmium (Cd) is an industrial and environmental pollutant that was shown to be involved in the development of some diseases. Due to high amounts of Cd in cigarettes, smokers and passive smokers are exposed to high amount of Cd. We aimed to determine whether Copper (Cu) supplementation would have a protective effect against Cd intoxication in pregnant rats and their fetuses.

METHODS

Experiments were performed on 27 adult female Wistar albino rats divided into three experimental groups. CdCl(2), CdCl(2) plus CuSO(4) and only drinking water was given to different groups for 21 days. We measured cadmium (Cd), malondialdehyde (MDA), reduced glutathione (GSH), myeloperoxidase (MPO), superoxide dismutase (SOD) and catalase (CAT) levels in dams' liver, dams' kidney, fetus liver, fetus kidney, and placenta of rats.

RESULTS

In all tissues of Cd and Cd + Cu-treated groups, Cd levels were found to be increased significantly when compared to control group. MDA levels and MPO activities were significantly increased whereas GSH levels, activities of SOD and CAT were decreased in Cd groups when compared to control group. Cu supplementation significantly prevented the increment in MDA levels and brought MPO activities back to control levels or below. Cd-induced reductions in GSH levels and SOD activities were also prevented by Cu supplementation. An increase of CAT activity after Cu supplementation was enough to revert to the control levels in some tissues.

CONCLUSIONS

Our findings suggest that Cu supplementation may have a protective effect against the Cd-induced oxidative stress in liver, kidney and placental tissues of pregnant rats and fetuses.

Extended lifespan of Drosophila parkin mutants through sequestration of redox-active metals and enhancement of anti-oxidative pathways

The mechanisms underlying neuron death in Parkinson's disease are unknown, but both genetic defects and environmental factors are implicated in its pathogenesis. Mutations in the parkin gene lead to autosomal recessive juvenile Parkinsonism (AR-JP). Here we report that compared to control flies, Drosophila lacking parkin show significantly reduced lifespan but no difference in dopamine neuron numbers when raised on food supplemented with environmental pesticides or mitochondrial toxins. Moreover, chelation of redox-active metals, anti-oxidants and overexpression of superoxide dismutase 1 all significantly reversed the reduced longevity of parkin-deficient flies. Finally, parkin deficiency exacerbated the rough eye phenotype of Drosophila caused by overexpression of the copper importer B (Ctr1B). Taken together, our results demonstrate an important function of parkin in the protection against redox-active metals and pesticides implicated in the etiology of Parkinson's disease. They also corroborate that oxidative stress, perhaps as a consequence of mitochondrial dysfunction, is a major determinant of morbidity in parkin mutant flies.