A molecular mechanism of aluminium-induced Alzheimer's disease?

Additive aluminum as a cause of induced immunoexcitoxicity resulting in neurodevelopmental and neurodegenerative disorders: A biochemical, pathophysiological, and pharmacological analysis

Much has been learned about the neurotoxicity of aluminum over the past several decades in terms of its ability to disrupt cellular function, result in slow accumulation, and the difficulty of its removal from cells. Newer evidence suggests a central pathophysiological mechanism may be responsible for much of the toxicity of aluminum and aluminofluoride compounds on the brain and spinal cord. This mechanism involves activation of the brain's innate immune system, primarily the microglia, astrocytes, and macrophages, with a release of neurotoxic concentrations of excitotoxins and proinflammatory cytokines, chemokines, and immune mediators. Many studies suggest that excitotoxicity plays a significant role in the neurotoxic action of several metals, including aluminum. Recently, researchers have found that while most of the chronic pathology involved in the observed neurodegenerative effects of these metals are secondary to prolonged inflammation, it is the enhancement of excitotoxicity by the immune mediators that are responsible for most of the metal's toxicity. This enhancement occurs through a crosstalk between cytokines and glutamate-related mechanisms. The author coined the name immunoexcitotoxicity to describe this process. This paper reviews the evidence linking immunoexcitotoxicity to aluminum's neurotoxic effects and that a slow accumulation of aluminum may be the cause of neurodevelopmental defects as well as neurodegeneration in the adult.

A novel Zebrafish model of Alzheimer's disease by Aluminium chloride; involving nitro-oxidative stress, neuroinflammation and cholinergic pathway

Alzheimer's disease (AD) is the most common form of dementia and is a progressive neurodegenerative disorder of the brain. Most AD experimental animal models are pharmacological or transgenic in origin. The existing pharmacological approaches for developing AD are poorly developed and most of them fail to replicate the complete characteristics of disease pathology. Developing a cost-effective and reliable experimental animal model will meet this research gap. Zebrafish (ZF) are progressively emerging as a powerful drug discovery disease model to evaluate central nervous system (CNS) disorders due to their homologous similarities to humans as well as cost-effectiveness. The present research is conceptualized to develop and evaluate a reliable ZF AD model using aluminum chloride (AlCl3). Chronic exposure of 0.04 mM of AlCl3 for 28 days increased the expression of amyloid-β, phosphorylated tau protein and senile plaque development in the ZF brain. The observed changes were associated with learning and memory impairment. Furthermore, decreased brain-derived neurotrophic factor (BDNF) level and elevated oxidative stress indices, pro-inflammatory cytokines levels and acetylcholine esterase (AChE) activity was observed upon exposure to AlCl3 in the ZF brain. Chronic exposure to 0.04 mM of AlCl3 would be a cost-effective ZF AD model for pharmacological screening and may also be used to unravel the molecular mechanism underlying the neuropathology of the disease.

Ni and Al mixture amplifies cerebellar oxido-inflammatory responses, down regulates AChE and BDNF/NGF levels in motor impairment in male albino rats

BACKGROUND

Aluminum and nickel are potent neurotoxicants to which humans are constantly exposed. Previous studies have demonstrated that these two metals can affect the motor system, but their effects on the cerebellum, a central nervous system region with the highest number of neurons, have remained largely unexplored. Therefore, we conducted a study to investigate the adverse effects of Al, Ni, and Al+Ni in vivo.

METHODS

In our study, seven male Sprague Dawley rats per group were orally exposed to deionized water, 0.2 mg/kg of Ni, 1 mg/kg of Al, and 0.2 mg/kg of Ni + 1 mg/kg of Al (as a binary heavy metals mixture; HMM), respectively.

RESULTS

Ni, Al, and HMM exposed rats accumulated higher levels of Al and Ni compared to controls, and HMM treated animals had higher levels of Ca and Fe in the cerebellum (p < 0.05). Malondialdehyde (MDA) levels were significantly (p < 0.05) higher in the HMM, Ni, and Al treated groups compared to the control group that received deionized water. Superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and glutathione peroxidase (GPx) activities were significantly (p < 0.05) reduced in the HMM, Ni, and Al treated groups compared to the control group that received deionized water. Ni, Al, and HMM significantly (p < 0.05) shortened the length of time of the grip in comparison to the control. Nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) levels were significantly decreased in the nickel, Al, and heavy metal mixture groups compared with the control group. Moreover, there was a significant decrease in the activity of acetylcholinesterase (AChE) and a increase in cyclooxygenase-2 (COX-2) activity in the Ni, Al, and HMM treated groups compared to the control group.

CONCLUSION

HMM exposed animals had significantly poorer performance in the Rotarod test (p < 0.05) than controls. Al and Ni induced impairment of cerebellar function at various levels.

Animal models of Alzheimer's disease: An originof innovativetreatments and insight to the disease's etiology

Alzheimer's disease (AD) is a progressive neurodegenerative disorder. The main pathogenic features are the development and depositionof senile plaques and neurofibrillary tangles in brain. Recent developments in the knowledge of the pathophysiological mechanisms behind Alzheimer's disease and other cognitive disorders have suggested new approaches to treatment development. These advancements have been significantly aided by the use of animal models, which are also essential for the assessment of therapies. Various approaches as transgenic animal model, chemical models, brain injury are used. This review will presentAD pathophysiology and emphasize several Alzheimer like dementia causingchemical substances, transgenic animal model and stereotaxy in order to enhance our existing knowledge of their mechanism of AD induction, dose, and treatment duration.

Effects of baicalein with memantine on aluminium chloride-induced neurotoxicity in Wistar rats

Alzheimer's disease is a progressive neurodegenerative condition. It is one of the most common 28 forms of dementia accounting for 60-80% of people suffering from dementia. There are very few medications that are approved for the treatment of Alzheimer's disease. Baicalein, belonging to the flavone subclass of flavonoids, has been reported to have a neuroprotective effect by reducing oxidative stress and neuroinflammation, inhibiting the AChE enzyme, and reducing amyloid protein aggregation and toxicity. Memantine is one of the most important drugs used for treating Alzheimer's disease. The purpose of this work was to study the effect of baicalein with memantine on aluminum chloride-induced neurotoxicity in Wistar rats. Aluminum chloride (100 mg/kg p.o.) was administered for 42 days in male Wistar rats to induce neurotoxicity. Baicalein alone (10 mg/kg) and a combination of baicalein (5 mg/kg and 10 mg/kg) with memantine (20 mg/kg) were administered for 42 days. Treatment of baicalein with memantine showed significant improvement in behavioral parameters. The combination reduced oxidative stress and the formation of β-Amyloid plaques and increased brain-derived neurotrophic factor (BDNF) expression. Based on findings, it can be concluded that treatment with baicalein and memantine may slow the progression of neurodegeneration in rats.

Preclinical Models for Alzheimer's Disease: Past, Present, and Future Approaches

A robust preclinical disease model is a primary requirement to understand the underlying mechanisms, signaling pathways, and drug screening for human diseases. Although various preclinical models are available for several diseases, clinical models for Alzheimer's disease (AD) remain underdeveloped and inaccurate. The pathophysiology of AD mainly includes the presence of amyloid plaques and neurofibrillary tangles (NFT). Furthermore, neuroinflammation and free radical generation also contribute to AD. Currently, there is a wide gap in scientific approaches to preventing AD progression. Most of the available drugs are limited to symptomatic relief and improve deteriorating cognitive functions. To mimic the pathogenesis of human AD, animal models like 3XTg-AD and 5XFAD are the primarily used mice models in AD therapeutics. Animal models for AD include intracerebroventricular-streptozotocin (ICV-STZ), amyloid beta-induced, colchicine-induced, etc., focusing on parameters such as cognitive decline and dementia. Unfortunately, the translational rate of the potential drug candidates in clinical trials is poor due to limitations in imitating human AD pathology in animal models. Therefore, the available preclinical models possess a gap in AD modeling. This paper presents an outline that critically assesses the applicability and limitations of the current approaches in disease modeling for AD. Also, we attempted to provide key suggestions for the best-fit model to evaluate potential therapies, which might improve therapy translation from preclinical studies to patients with AD.

Neurotoxic effects of aluminium exposure as a potential risk factor for Alzheimer's disease

Aluminium is one of the most widely distributed elements of the Earth's crust. Its routine use has resulted in excessive human exposure and due to the potential neurotoxic effects has attained a huge interest in recent years. Despite its ubiquitous abundance, aluminium has no crucial biological functions in the human body. Oxidative stress and neuroinflammatory effects are attributed to its neurotoxic manifestations implicated in Alzheimer's disease. In this review, we have discussed the neuroinflammatory and neurodegenerative events in the brain induced by aluminium exposure. We have highlighted the neurotoxic events caused by aluminium, such as oxidative stress, apoptosis, inflammatory events, calcium dyshomeostasis, Aβ deposition, and neurofibrillary tangle formation in the brain. In addition, the protective measures needed for prevention of aluminium-induced neuronal dysregulations have also been discussed.

Sexual dimorphism in inorganic mercury toxicokinetics and the attendant lipotoxic and non-lipotoxic dyslipidemia in the rat

The influence of variability in the biology of living organisms is poorly appreciated in toxicology. However, multiple lines of evidence indicate that sex-differences modulate toxicokinetics and toxicodynamics from cellular/molecular to whole animal levels resulting in different toxic responses of living organisms to xenobiotics exposure. In order to investigate the influence of sex in inorganic mercury (Hg) exposure, male and female Wistar rats were exposed to 0.5, 1.0 and 1.5 mg Hg/kg body weight orally as HgCl₂ twice a week for 12 weeks. Higher Hg levels in the females (except heart) as compared to males were observed in the animals. At the highest dose of inorganic Hg, female renal Hg content was 3.3 times higher than that of the males. Mixed sexual dimorphism characterised circulating-lipid- and organ-lipid lipotoxic and non-lipotoxic dyslipidemia. The highest dose of inorganic Hg, induced hypercholesterolemia in the males as opposed to hypocholesterolemia in the female. Plasma and erythrocyte free fatty acids increased in both sexes, although the increase was more pronounced in the male. Reverse cholesterol transport was inhibited in the male at the highest dose of Hg, whereas female HDL became enriched with cholesterol. Female erythrocytes had all their lipids increased, whereas only male erythrocyte triglyceride increased. Brain cholesterol and phospholipids, and splenic phospholipids were depleted in both sexes. Our findings indicate that inorganic Hg exposure appears to affect Hg and lipid kinetics differently in both sexes, thus underscoring the need to develop sex-tailored approaches in the treatment of metal toxicosis and its metabolic outcomes.

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The influence of sex in inorganic Hg exposure was investigated in the rat.

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Higher Hg levels in females compared to males were observed.

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Sexual dimorphism characterised inorganic Hg-induced dyslipidemia.

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Inorganic Hg exposure affects Hg and lipid kinetics differently in both sexes.

Aluminium Induced Neurodegeneration in Rat Cerebellum in the Presence of Ethanol Coexposure

Introduction:

Both aluminium and ethanol are pro-oxidants and neurotoxic. Moderately intake of alcohol may favor the body in coronary heart disease and diabetes mellitus etc. Being cheaper aluminium and increasing consumption of alcohol in India mixed with each other and may induce neurotoxicity. The present study was planned to identify the level of aluminium induced neurodegeneration in presence of ethanol coexposure in the cerebellum.

Materials and Methods:

An experimental study was carried out at Dr. RP Government Medical College, Kangra, and Government Medical College, Amritsar, India after due approval from the Institute Animal Ethics Committee. Thirty-two Wistar rats were divided into one vehicle control and three experimental groups. Group I received the normal saline water as the vehicle control group. Group II received aluminium chloride 4.2 mg/kg body weight as the experimental group. Group III received ethanol 1 g/kg body weight as the experimental group. Group IV received both aluminium chloride 4.2 mg/kg body weight and ethanol 1 g/kg body weight as the experimental group. After 3 months of treatment, cerebellum was processed for histopathological observation under the microscope.

Results:

Experimental group treated with aluminium and ethanol separately showed reduction in the number of Purkinje cells, without a prominent nucleolus and well-defined nuclear membrane. Eosinophilic swelling adjacent to Purkinje cell bodies observed. The effects of combined administration of aluminium ethanol treated groups showed with acute neurodegeneration of Purkinje cell layer and granular layer. Pyknosis and neurofibrillary tangle seen in Purkinje cells.

Conclusions:

It has been suggested that the ethanol-induced the effects of aluminium on the cerebellum and plays a significant role in neurotoxicity.

Anticholinesterase activity and antioxidant properties of Heinsia crinita and Pterocarpus soyauxii in Drosophila melanogaster model

Background

Plant alkaloids have become important sources of nutraceuticals owing to their pharmacological importance especially in the management of neurodegenerative diseases such as Alzheimer’s disease. In assessing the therapeutic potentials of plant phytochemicals, the fruit fly (Drosophila melanogaster) has emerged as a very veritable tool and has been largely accepted as an alternative model in biomedical research.

Objectives

In this study, alkaloid extracts from bush apple (Heinsia crinita (Afzel.) G. Taylor and padauk (Pterocarpus soyauxii Taub.) leaves were assessed on D. melanogaster exposed to aluminum toxicity.

Materials and methods

Alkaloid extracts were prepared by solvent extraction method. Thereafter, the extracts were evaluated for their in vitro antioxidant properties, Fe²⁺-chelating abilities and inhibitory effects on drosophila acetylcholinesterase (AChE) activity. The samples were also characterized for their constituent alkaloids via HPLC. Thereafter, effective safe dose of the extracts were determined in D. melanogaster (Harwich strain). Subsequently, flies assaulted with AlCl₃ were co-treated with the extracts (8.3 and 16.6 μg/g) for seven days, during which their survival rate was monitored. This was followed by assaying for the activities of AChE, antioxidant enzymes [superoxide dismutase (SOD), catalase and glutathione-S-transferase (GST)]. Also, the flies were assayed for levels of thiobarbituric acid reaction substance (TBARS) and reactive oxygen species (ROS).

Results

The results revealed that both extracts showed in vitro antioxidant properties with Padauk showing significantly higher antioxidant properties in vitro. However, there was no significant difference in their in vitro AChE inhibition. In vivo, Al-induced toxicity reduced survival rate, elevated AChE, SOD and GST activities, as well as TBARS and ROS levels which were ameliorated by the extracts. It was also revealed that piperine was predominant in PA, while 1-cyclohexen-1-yl-pyrrolidine was predominant in BA.

Conclusion

Our data suggest that the protective abilities of these extracts against Al-induced toxicity can be primarily associated with their anticholinesterase and metal chelating abilities. Thus, these vegetables can be potential sources of nutraceuticals against aluminum toxicity and associated diseases.

Neuroprotective effects of Fraxinus angustifolia Vahl. bark extract against Alzheimer's disease

Alzheimer disease's (AD) is a neurodegenerative disease induced by amyloid-β (Aβ) aggregation and accumulation of neurotoxic metals in the brain. Fraxinus angustifolia Vahl. (Oleaceae) is a Mediterranean plant traditionally used to treat several human problems as nervous system problems. This study aimed to evaluate the neuroprotective effects of F. angustifolia Vahl. bark extract (FAB) in vitro and in vivo against Aβ-aggregation and aluminium induced-neurotoxicity in mice. FAB was characterized by colorimetric methods and its individual compounds were identified and quantified by LC-MS. First, the neuroprotective effect of FAB was evaluated against Aβ_25-35-aggregation where it was directly incubated with Aβ_25-35 and the kinetic of aggregation was measured by spectrophotometer at 200 nm. Then, the extract was tested against Aβ_25-35-induced cytotoxicity on PC12 cells and the cells viability was determined by MTT test. On the other hand, FAB (0.01-0.5 mg/mL) was tested against aluminium-activated lipid peroxidation in mice synaptosomal membranes, and in vivo against aluminium-caused neurotoxicity in male N.M.R.I. (Naval Medical Research Institute) mice; this test consisted of daily co-administration of the extract with Al for 60 days. At the end of the treatment, behavioral and memory tests (locomotor activity, black and white and Morris water maze tests) and histological analysis were realized. The identification and quantification of FAB phenolics revealed the presence of different phenolic classes with high concentration of phenylethanoids and hydroxycoumarins. FAB showed a high Aβ_25-35 anti-aggregative effect and a dose dependent protective effect on PC12 cells. The extract also demonstrated a significant inhibition of lipid peroxidation and was found to prevent the Al harmful effects where it significantly increased the locomotor activity, decreased the anxiety, improved memory and reduced histological alterations. In conclusion, FAB is rich of bioactive compounds that gave it the ability to inhibit Aβ-aggregation and Al-caused neurotoxicity in mice.

The Nutritional Components of Beer and Its Relationship with Neurodegeneration and Alzheimer's Disease

The prevalence of degenerative diseases has risen in western countries. Growing evidence suggests that demenia and other cognition affectations are associated with ambient factors including specific nutrients, food ingredients or specific dietary patterns. Mediterranean diet adherence has been associated with various health benefits and decreased risk of many diseases, including neurodegenerative disorders. Beer, as part of this protective diet, contains compounds such as silicon and hops that could play a major role in preventing brain disorders. In this review, different topics regarding Mediterranean diet, beer and the consumption of their main compounds and their relation to neurological health have been addressed. Taking into account published results from our group and other studies, the hypothesis linking aluminum intoxication with dementia and/or Alzheimer’s disease and the potential role of regular beer has also been considered. Beer, in spite of its alcohol content, may have some health benefits; nonetheless, its consumption is not adequate for all subjects. Thus, this review analyzed some promising results of non-alcoholic beer on several mechanisms engaged in neurodegeneration such as inflammation, oxidation, and cholinesterase activity, and their contribution to the behavioral modifications induced by aluminum intoxication. The review ends by giving conclusions and suggesting future topics of research related to moderate beer consumption and/or the consumption of its major compounds as a potential instrument for protecting against neurodegenerative disease progression and the need to develop nutrigenetic and nutrigenomic studies in aged people and animal models.

Impacts of Egyptian propolis extract on rat cerebellum intoxicated by aluminum silicate: histopathological studies

Human is exposed to traces of aluminum silicate (AlS), i.e., cosmetics, pesticides. Accumulation of aluminum compounds including AlS is associated with neuropathological diseases, e.g., Alzheimer's disease. The aim of the current study is to investigate the neuroprotective effects of propolis extracts in AlS-induced cerebellum intoxication in rats. Forty adult rats were randomly divided into four groups (n = 10). The first group served as a control; the second group treated with 200 ml propolis/kg bwt. every other day by stomach gavage tube, third group was intraperitoneally injected with AIS (20 mg/kg) twice a week for 8 weeks, and the fourth group received propolis extract and AIS. At the end of 8 weeks, the cerebellum was harvested for further ultrastructure, histological, and histochemical investigations. Using electron microscopy, the ultrastructure of the cerebellar cortex of AlS intoxicated rats showed Purkinje cells with an irregular euchromatic nucleus and extremely increased invagination of the nuclear envelope. In addition, the cytoplasm revealed numerous damaged mitochondria (> 20%) as well as swollen lysosomes (> 40%) compared to controls. These AlS-related ultrastructure changes were to some extent normalized to < 10% and < 30% in case of mitochondria and lysosomes, respectively, if rats were co-treated with propolis extract. Further, histopathological examination showed that AlS-exposed rats revealed abnormal Purkinje cells with irregular size and shrank shape, evidence of pre-necrotic stage in the form of nuclear pyknosis, and condensed and frequent darkly stained cells in cerebellar layers. However, propolis extract co-administration reversed from 35 to 25% (p < 0.05) these alterations. The carbohydrate and protein contents were reduced in case of AlS treatment and surprisingly propolis co-treatment was able to rescue these neurotoxic effects. Propolis extract might have neuroprotective effects against AIS-induced toxicity. Further studies are required to identify the mechanism of the pharmacological action and optimal settings for medical testing of propolis extract.

Effects of Al Exposure on Mitochondrial Dynamics in Rat Hippocampus

Aluminum (Al) exposure impairs learning and memory function in humans and in animal models. Several studies have shown that the neurotoxicity of Al is associated with damage to mitochondrial morphology and mitochondrial dysfunction, but the molecular mechanism is unclear. The present study was performed to elucidate the possible molecular mechanism related to the Al-induced abnormal mitochondrial dynamics that lead to learning and memory disorders. SD rats were exposed to Al-maltolate complex (Al(mal)₃) (blank, 0, 0.41, 0.81, or 1.62 mg/kg) for 30, 60, or 90 days, and neurobehavior, mitochondrial morphology, mitochondrial function, the levels of fission proteins such as dynamin-related protein 1 (Drp1) and fission protein 1 (Fis1), and the levels of fusion proteins such as optic atrophy 1 (Opa1), mitofusin 1 (Mfn1), and mitofusin 2 (Mfn2) were explored. The results indicated that exposure to Al(mal)₃ increased the concentration of Al in the brain in a time- and dose-dependent manner and impaired spatial learning and memory. Al(mal)₃ damaged mitochondrial morphology and impaired mitochondrial function in the hippocampus. Dose-dependent elevations in the levels of mitochondrial fission (Drp1 and Fis1) and fusion (Opa1, Mfn1, and Mfn2) proteins were observed. In addition, the upregulation of calcineurin (CaN) and the reduced phosphorylation of Drp1 (s637) may have disturbed the balance of mitochondrial fission and fusion in the hippocampus. These results showed that Al-induced learning and memory impairment may be related to mitochondrial fission and fusion disorders.

Evaluation of neuroprotective effects of wedelolactone and gallic acid on aluminium-induced neurodegeneration: Relevance to sporadic amyotrophic lateral sclerosis

Al exposure causes an alteration in the several ions in the body and causes toxicity. Such as apoptosis, oxidative stress, disruption in neuronal transport, mitochondrial damage, excitotoxicity, generation of inflammatory mediators, and microglial activation. These multiple mechanisms lead to the several neurodegenerative diseases, including sporadic amyotrophic lateral sclerosis (sALS). The study aims to unravel the mechanisms behind the neuroprotective effects of wedelolactone (WL) and gallic acid (GA) against aluminium-induced neurodegeneration and thereby to unlock a platform to find a cure for sALS. We studied the neuroprotective effects of WL (100 & 200 mg/kg) and GA (100 & 200 mg/kg) using aluminium chloride (AlCl₃)-induced neurodegeneration model. The study was conducted using male Wistar rats. We assessed the effects of WL and GA on motor learning ability, motor coordination, locomotor activity, cytokine production, BDNF, glutathione peroxidase (GPx), m-calpain, caspase-3 inhibition and L-glutamate level. The study suggests that the treatment with WL and GA could protect the motor neurons from the toxicity that caused by Al via improving the antioxidant status, BDNF, and by preventing glutamate excitotoxicity. Also, WL and GA are found to be effective in inhibiting caspase-3 activation and downregulating inflammatory cytokines. WL and GA also found effective in improving the motor learning abilities and motor coordination in rats. The protective effects of the WL and GA were further confirmed from histopathological results. WL and GA prevent the neurofibrillary tangle formation and neuronal damage. The study concluded that the WL and GA were dose-dependently effective in managing the AlCl₃-induced neurodegeneration.

Behavioral effects of long-term oral administration of aluminum ammonium sulfate in male and female C57BL/6J mice

Background

Aluminum (Al) is considered to be a neurotoxic metal, and excessive exposure to Al has been reported to be a potential risk factor for neurodegenerative diseases. Al ammonium sulfate is one of the Al compounds that is widely used as a food additive. However, the effects of the oral administration of Al ammonium sulfate on physical development and behavior remain to be examined.

Methods

In this study, we investigated the effects of the administration of Al ammonium sulfate 12‐water dissolved in drinking water (0.075 mg/mL) beginning in adolescence on various types of behavior in adult female C57BL/6J mice through a battery of behavioral tests (low‐dose experiment; Experiment 1). We further examined the behavioral effects of the oral administration of a higher dose of the Al compound in drinking water (1 mg/mL) beginning in the prenatal period on behavior in adult male and female mice (high‐dose experiment; Experiment 2).

Results

In the low‐dose experiment, in which females’ oral intake of Al was estimated to be 0.97 mg Al/kg/d as adults, Al‐treated females exhibited an increase in total arm entries in the elevated plus maze test, an initial decrease and subsequent increase in immobility in the forced swim test, and reduced freezing in the fear conditioning test approximately 1 month after the conditioning session compared with vehicle‐treated females (uncorrected P < .05). However, the behavioral differences did not reach a statistically significant level after correction for multiple testing. In the high‐dose experiment, in which animals’ oral intakes were estimated to be about ten times higher than those in the low‐dose experiment, behavioral differences found in the low‐dose experiment were not observed in high‐dose Al‐treated mice, suggesting that the results of the low‐dose experiment might be false positives. Additionally, although high‐dose Al‐treated females exhibited increased social contacts with unfamiliar conspecifics and impaired reference memory performance, and high‐dose Al‐treated mice exhibited decreases in prepulse inhibition and in correct responses in the working memory task (uncorrected P < .05), the differences in any of the behavioral measures did not reach the significance level after correction for multiple testing.

Conclusion

Our results show that long‐term oral exposure to Al ammonium sulfate at the doses used in this study may have the potential to induce some behavioral changes in C57BL/6J mice. However, the behavioral effects of Al were small and statistically weak, as indicated by the fact that the results failed to reach the study‐wide significance level. Thus, further study will be needed to replicate the results and reevaluate the behavioral outcomes of oral intake of Al ammonium sulfate.

Aluminum (Al) ammonium sulfate was orally administered to C57BL/6J mice (estimated dose of 0.97‐9.78 Al mg/kg/d). Behavioral effects of Al were assessed in a battery of behavioral tests in mice in adulthood. Statistically significant behavioral differences were not found between Al‐ and vehicle‐treated mice.

A new tripodal-3-hydroxy-4-pyridinone for iron and aluminium sequestration: synthesis, complexation and in vivo studies

A new highly efficient tris-hydroxypyridinone chelator for iron and aluminum, with promising capacity as a potential metal decorporation agent.

Complexation behaviour of caffeic, ferulic and p-coumaric acids towards aluminium cations: a combined experimental and theoretical approach

The formation of complexes of hydroxycinnamic acids with Al(iii) ions is strongly pH-dependent and the complexation occurs via a carboxylic function.

Multifaceted effects of aluminium in neurodegenerative diseases: A review

Aluminium (Al) is the most common metal and widely distributed in our environment. Al was first isolated as an element in 1827, and its use began only after 1886. Al is widely used for industrial applications and consumer products. Apart from these it is also used in cooking utensils and in pharmacological agents, including antacids and antiperspirants from which the element usually enters into the human body. Evidence for the neurotoxicity of Al is described in various studies, but still the exact mechanism of Al toxicity is not known. However, the evidence suggests that the Al can potentiate oxidative stress and inflammatory events and finally leads to cell death. Al is considered as a well-established neurotoxin and have a link between the exposure and development of neurodegenerative diseases, including Amyotrophic Lateral Sclerosis (ALS), Alzheimer's disease (AD), dementia, Gulf war syndrome and Parkinsonism. Here, we review the detailed possible pathogenesis of Al neurotoxicity. This review summarizes Al induced events likewise oxidative stress, cell mediated toxicity, apoptosis, inflammatory events in the brain, glutamate toxicity, effects on calcium homeostasis, gene expression and Al induced Neurofibrillary tangle (NFT) formation. Apart from these we also discussed animal models that are commonly used for Al induced neurotoxicity and neurodegeneration studies. These models help to find out a better way to treat and prevent the progression in Al induced neurodegenerative diseases.

Understanding Aspects of Aluminum Exposure in Alzheimer's Disease Development

Aluminum is a ubiquitously abundant nonessential element. Aluminum has been associated with neurodegenerative diseases such as Alzheimer's disease (AD), amyotrophic lateral sclerosis, and dialysis encephalopathy. Many continue to regard aluminum as controversial although increasing evidence supports the implications of aluminum in the pathogenesis of AD. Aluminum causes the accumulation of tau protein and Aβ protein in the brain of experimental animals. Aluminum induces neuronal apoptosis in vivo and in vitro, either by endoplasmic stress from the unfolded protein response, by mitochondrial dysfunction, or a combination of them. Some, people who are exposed chronically to aluminum, either from through water and/or food, have not shown any AD pathology, apparently because their gastrointestinal barrier is more effective. This article is written keeping in mind mechanisms of action of aluminum neurotoxicity with respect to AD.

Influence of Some Mineral Ions on Lipid Peroxidation in Vitro

Recently, a growing interest has been recorded in mineral content of mammalian diet, which might impair their development. Focused on the topic, we studied the effect of Al3+, Si4+, Sr2+ and Na2S on the intensity of malondialdehyde (MDA) production in vitro. MDA, as one of oxidative stress markers, was determined in rat brain homogenates in the conditions of lipid peroxidation (LP) activated by iron ions and ascorbate. Our results showed a significant increase in lipid peroxidation after addition of aluminium ions. We assume a probable impact of Al3+ on active or regulatory centres of antioxidant enzymes, resulting in the reduction of their antioxidant functions. The addition to Si4+ or Na2S to samples with Al3+ significantly decreased Fe2+-activated LP. We can explain the influence of Na2S by the formation of insoluble complexes with iron. Similarly, the effect of Si4+ can be related to the production of aluminium-silicon complexes. In our view, an optimal ratio of aluminium and silicon ions (or aluminium ions and Na2S) in the diet might have beneficial effects on brain functions.

A highly selective fluorescent sensor for Al3+ and the use of the resulting complex as a secondary sensor for PPi in aqueous media: its applicability in live cell imaging

An “off–on–off” reversible fluorescent sensor has been developed for sequential detection of Al³⁺ and PPi in aqueous media, and has further been applied to live cell imaging.

Why industry propaganda and political interference cannot disguise the inevitable role played by human exposure to aluminum in neurodegenerative diseases, including Alzheimer's disease

In the aluminum age, it is clearly unpalatable for aluminum, the globe’s most successful metal, to be implicated in human disease. It is unpalatable because for approximately 100 years human beings have reaped the rewards of the most abundant metal of the Earth’s crust without seriously considering the potential consequences for human health. The aluminum industry is a pillar of the developed and developing world and irrespective of the tyranny of human exposure to aluminum it cannot be challenged without significant consequences for businesses, economies, and governments. However, no matter how deep the dependency or unthinkable the withdrawal, science continues to document, if not too slowly, a burgeoning body burden of aluminum in human beings. Herein, I will make the case that it is inevitable both today and in the future that an individual’s exposure to aluminum is impacting upon their health and is already contributing to, if not causing, chronic diseases such as Alzheimer’s disease. This is the logical, if uncomfortable, consequence of living in the aluminum age.

Are there negative CNS impacts of aluminum adjuvants used in vaccines and immunotherapy?

In spite of a common view that aluminum (Al) salts are inert and therefore harmless as vaccine adjuvants or in immunotherapy, the reality is quite different. In the following article we briefly review the literature on Al neurotoxicity and the use of Al salts as vaccine adjuvants and consider not only direct toxic actions on the nervous system, but also the potential impact for triggering autoimmunity. Autoimmune and inflammatory responses affecting the CNS appear to underlie some forms of neurological disease, including developmental disorders. Al has been demonstrated to impact the CNS at every level, including by changing gene expression. These outcomes should raise concerns about the increasing use of Al salts as vaccine adjuvants and for the application as more general immune stimulants.

Insights into the coordination mode of quercetin with the Al(III) ion from a combined experimental and theoretical study

Combining potentiometric, spectroscopic and theoretical DFT computations we have studied the formation of the Al(iii)-quercetin complex in ethanol solution. The possible complexation sites have been considered on the basis of all the experimental and theoretical tools used. Results supported proposing a 1 : 1 neutral complex and the possibility to have different isomers in solution.

Degradable borate glass polyalkenoate cements

Glass polyalkenoate cements (GPCs) containing aluminum-free borate glasses having the general composition Ag2O-Na2O-CaO-SrO-ZnO-TiO2-B2O3 were evaluated in this work. An initial screening study of sixteen compositions was used to identify regions of glass formation and cement compositions with promising rheological properties. The results of the screening study were used to develop four model borate glass compositions for further study. A second round of rheological experiments was used to identify a preferred GPC formulation for each model glass composition. The model borate glasses containing higher levels of TiO2 (7.5 mol %) tended to have longer working times and shorter setting times. Dissolution behavior of the four model GPC formulations was evaluated by measuring ion release profiles as a function of time. All four GPC formulations showed evidence of incongruent dissolution behavior when considering the relative release profiles of sodium and boron, although the exact dissolution profile of the glass was presumably obscured by the polymeric cement matrix. Compression testing was undertaken to evaluate cement strength over time during immersion in water. The cements containing the borate glass with 7.5 mol % TiO2 had the highest initial compressive strength, ranging between 20 and 30 MPa. No beneficial aging effect was observed-instead, the strength of all four model GPC formulations was found to degrade with time.

Ferrous iron formation following the co-aggregation of ferric iron and the Alzheimer's disease peptide β-amyloid (1-42)

For decades, a link between increased levels of iron and areas of Alzheimer's disease (AD) pathology has been recognized, including AD lesions comprised of the peptide β-amyloid (Aβ). Despite many observations of this association, the relationship between Aβ and iron is poorly understood. Using X-ray microspectroscopy, X-ray absorption spectroscopy, electron microscopy and spectrophotometric iron(II) quantification techniques, we examine the interaction between Aβ(1–42) and synthetic iron(III), reminiscent of ferric iron stores in the brain. We report Aβ to be capable of accumulating iron(III) within amyloid aggregates, with this process resulting in Aβ-mediated reduction of iron(III) to a redox-active iron(II) phase. Additionally, we show that the presence of aluminium increases the reductive capacity of Aβ, enabling the redox cycling of the iron. These results demonstrate the ability of Aβ to accumulate iron, offering an explanation for previously observed local increases in iron concentration associated with AD lesions. Furthermore, the ability of iron to form redox-active iron phases from ferric precursors provides an origin both for the redox-active iron previously witnessed in AD tissue, and the increased levels of oxidative stress characteristic of AD. These interactions between Aβ and iron deliver valuable insights into the process of AD progression, which may ultimately provide targets for disease therapies.

Environmental and dietary risk factors in Alzheimer’s disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease that affects millions in the aging population worldwide and will affect millions more in the next 20 years. Over 90% of all cases are sporadic, with genetics playing a minor role in the etiology of AD. Therefore, it is crucial to investigate the environment and diet as primary risk factors in AD pathology. This review considers epidemiologic case control studies, and in vitro and in vivo research to investigate the potential of environmental exposure to metals, air pollution and pesticides as well as diet as risk factors for AD. In some cases, the role of genetic mutations and environmental risk is discussed. The evidence examined in this review provides a brief overview of the current literature on selected, significant risk factors in promoting amyloid-beta accumulation and aggregation, thus contributing to neurodegeneration.

High-aluminum-affinity silica is a nanoparticle that seeds secondary aluminosilicate formation

Despite the importance and abundance of aluminosilicates throughout our natural surroundings, their formation at neutral pH is, surprisingly, a matter of considerable debate. From our experiments in dilute aluminum and silica containing solutions (pH ~ 7) we previously identified a silica polymer with an extraordinarily high affinity for aluminium ions (high-aluminum-affinity silica polymer, HSP). Here, further characterization shows that HSP is a colloid of approximately 2.4 nm in diameter with a mean specific surface area of about 1,000 m(2) g(-1) and it competes effectively with transferrin for Al(III) binding. Aluminum binding to HSP strongly inhibited its decomposition whilst the reaction rate constant for the formation of the β-silicomolybdic acid complex indicated a diameter between 3.6 and 4.1 nm for these aluminum-containing nanoparticles. Similarly, high resolution microscopic analysis of the air dried aluminum-containing silica colloid solution revealed 3.9 ± 1.3 nm sized crystalline Al-rich silica nanoparticles (ASP) with an estimated Al:Si ratio of between 2 and 3 which is close to the range of secondary aluminosilicates such as imogolite. Thus the high-aluminum-affinity silica polymer is a nanoparticle that seeds early aluminosilicate formation through highly competitive binding of Al(III) ions. In niche environments, especially in vivo, this may serve as an alternative mechanism to polyhydroxy Al(III) species binding monomeric silica to form early phase, non-toxic aluminosilicates.

A Novel Glass Polyalkenoate Cement for Fixation and Stabilisation of the Ribcage, Post Sternotomy Surgery: An ex-Vivo Study

This study investigates the use of gallium (Ga) based glass polyalkenoate cements (GPCs) as a possible alternative adhesive in sternal fixation, post sternotomy surgery. The glass series consists of a Control (CaO-ZnO-SiO2), and LGa-1 and LGa-2 which contain Ga at the expense of zinc (Zn) in 0.08 mol% increments. The additions of Ga resulted in increased working time (75 s to 137 s) and setting time (113 to 254 s). Fourier Transform Infrared (FTIR) analysis indicated that this was a direct result of increased unreacted poly(acrylic acid) (PAA) and the reduction of crosslink formation during cement maturation. LGa samples (0.16 wt % Ga) resulted in an altered ion release profile, particularly for 30 days analysis, with maximum Ca2+, Zn2+, Si4+ and Ga3+ ions released into the distilled water. The additions of Ga resulted in increased roughness and decreased contact angles during cement maturation. The presence of Ga has a positive effect on the compressive strength of the samples with strengths increasing over 10 MPa at 7 days analysis compared to the 1 day results. The additions of Ga had relatively no effect on the flexural strength. Tensile testing of bovine sterna proved that the LGa samples (0.16 wt % Ga) are comparable to the Control samples.

Human exposure to aluminium

Human activities have circumvented the efficient geochemical cycling of aluminium within the lithosphere and therewith opened a door, which was previously only ajar, onto the biotic cycle to instigate and promote the accumulation of aluminium in biota and especially humans. Neither these relatively recent activities nor the entry of aluminium into the living cycle are showing any signs of abating and it is thus now imperative that we understand as fully as possible how humans are exposed to aluminium and the future consequences of a burgeoning exposure and body burden. The aluminium age is upon us and there is now an urgent need to understand how to live safely and effectively with aluminium.

Luminescent Fluorene-Based Bis-Pyrazolyl Aniline Ligand for Aluminum Detection

The design, synthesis, and photophysical properties of a new fluorene-based fluorescent chemosensor, 4-((E)-2-(2-(benzo[d]thiazol-2-yl)-9,9-diethyl-9H-fluoren-7-yl)vinyl)-N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)benzenamine (AXF-Al), is described for the detection of Al3+. AXF-Al exhibited absorption at 382 nm and strong fluorescence emission at 542 nm (fluorescence quantum yield, Φ F, of 0.80). The capture of Al3+ by the pyrazolyl aniline receptor resulted in nominal change in the linear absorption (372 nm) but a large hypsochromic shift of 161 nm in the fluorescence spectrum (542 to 433 nm, Φ F = 0.88), from which Al3+ was detected both ratiometrically and colorimetrically. The addition of other metal ions, namely Mg2+, Ca2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg 2+ and Pb2+, produced only minimal changes in the optical properties of this probe. The emission band of this probe was also accessed by two-photon excitation in the near-IR, as two-photon absorption (2PA) is important for potential applications in two-photon fluorescence microscopy (2PFM) imaging. The 2PA cross section of the free fluorenyl ligand AXF-Al was 220 GM at 810 nm and 235 GM at 810 nm for the Al-ligand complex, practically useful properties for 2PFM.

pH influence on the complexation site of Al(III) with protocatechuic acid. A spectroscopic and theoretical approach

Electronic spectroscopy techniques with the aid of quantum chemical calculations, and notably the Time-Dependent Density Functional Theory, can be used to probe the structure of metal complexes in solution. Here, we report the characterization of Al(III)-protocatechuate in aqueous solution, at pH=6.5. The exploitation of the UV-vis spectra of the system by chemometric methods highlights the formation of a single complex of stoichiometry 1:1. From different structural hypothesis, the comparison of theoretical and experimental spectra shows that Al(III) forms a monodentate complex with the carboxylate function. This hypothesis is confirmed by the calculation of the complexation reaction pathways. Previous studies report the formation of a chelate involving the ortho-dihydroxyl group, at pH=3.5. These results illustrate the important dependence of the protonation state of the carboxylic function on the Al(III) fixation site on the studied ligand.

Molecular structure of tetraaqua adenosine 5'-triphosphate aluminium(III) complex: a study involving Raman spectroscopy, theoretical DFT and potentiometry

The Alzheimer's disease is one of the most common neurodegenerative diseases that affect elderly population, due to the formation of β-amyloid protein aggregate and several symptoms, especially progressive cognitive decline. The result is a decrease in capture of glucose by cells leading to obliteration, meddling in the Krebs cycle, the principal biochemical route to the energy production leading to a decline in the levels of adenosine 5'-triphosphate. Aluminium(III) is connected to Alzheimer's and its ion provides raise fluidity of the plasma membrane, decrease cell viability and aggregation of amyloid plaques. Studies reveal that AlATP complex promotes the formation of reactive fibrils of β-amyloid protein and independent amyloidogenic peptides, suggesting the action of the complex as a chaperone in the role pathogenic process. In this research, one of complexes formed by Al(III) and adenosine 5'-triphosphate in aqueous solution is analyzed by potentiometry, Raman spectroscopy and ab initio calculations. The value of the logK(AlATP) found was 9.21±0.01 and adenosine 5'-triphosphate should act as a bidentate ligand in the complex. Raman spectroscopy and potentiometry indicate that donor atoms are the oxygen of the phosphate β and the oxygen of the phosphate γ, the terminal phosphates. Computational calculations using Density Functional Theory, with hybrid functions B3LYP and 6-311++G(d,p) basis set regarding water solvent effects, have confirmed the results. Frontier molecular orbitals, electrostatic potential contour surface, electrostatic potential mapped and Mulliken charges of the title molecule were also investigated.

Aluminium-induced imbalance in oxidant and antioxidant determinants in brain regions of female rats: protection by centrophenoxine

The present study was carried out to investigate the potential of centrophenoxine in modulating aluminium-induced neurotoxicity. Female Sprague Dawley rats were administered aluminium chloride orally (40 mg/kg b.w./day) for a period of 8 weeks. At the end of respective treatment, various markers of oxidative stress were determined in four different regions of brain: cerebrum cerebellum, medulla oblongata, and hypothalamus. Lipid peroxidation assay was also carried out using standard techniques. Simultaneously, the centrophenoxine group (100 mg/kg b.w./day) for 6 weeks was also run long to understand the role in ameliorating oxidative damage. A significant decrease in the activities of superoxide dismutase and catalase was noticed in all the four regions, the most significant being in the hypothalamus (0.603 +/- .06) and cerebrum (0.038 +/- .01). Due to aluminium toxicity, peroxidation of lipids was also found to be elevated in cerebrum (0.424 +/- .03), cerebellum (0.341 +/- .03), hypothalamus (1.018 +/- .007), and medulla oblongata (0.304 +/- .05). However, posttreatment with centrophenoxine significantly elevated the superoxide and catalase activities in different regions. In addition, lipid peroxidation status of membranes was significantly reduced after centrophenoxine posttreatment to aluminium-exposed animals. Centrophenoxine has proved to be beneficial in combating the damage caused by aluminium toxicity. However, further research is needed to have a better understanding of the molecular basis of aluminium-induced oxidative damage. In addition, the different aspects of centrophenoxine need to be unmasked.

Cortico-hippocampal salvage in chronic aluminium induced neurodegeneration by Celastrus paniculatus seed oil: Neurobehavioural, biochemical, histological study

OBJECTIVE

To investigate the effects of Celastrus paniculatus seed oil in preventing the onset of chronic aluminum induced cortico-hippocampal neurodegeneration and oxidative stress.

MATERIALS AND METHODS

An animal model of senile dementia of Alzheimer's type was produced by administering aluminum as aluminum chloride (4.2 mg/kg) intraperitoneally to male Wistar rats for 60 days and results compared to untreated control. Neurobehavioral investigations of Morris water maze tests, passive avoidance test, rotarod test and biochemical estimations of acetylcholineterase, malondialdehyde, glucose-6-phosphate dehydrogenase, superoxide dismutase, and hemoglobin in blood were performed fortnightly which gauged the extent of global oxidative stress and progressive neural damage. Findings were fortified by the above enzyme assays and histology of brain at necropsy. Prophylactic oral C. paniculatus in two doses 0.5 ml and 1 ml, were given to animals and the results were analyzed in comparison to a similar rodent model with standard drug donepezil (0.5 mg/kg) intraperitoneally.

RESULTS

C. paniculatus showed a significant prevention in onset of aluminum induced neural insult and overall systemic oxidative stress which was corroborated by the enlisted neurobehavioral, biochemical, and histological evidence.

CONCLUSION

C. paniculatus is a putative decelerator of Al-mediated Alzheimer's like pathobiology.

Does elevating silver content in zinc-based glass polyalkenoate cements increase their antibacterial efficacy against two common bacteria using the agar gel diffusion method?

The authors have previously shown that it is possible to incorporate silver into a soda-zinc-silicate glass and subsequently form a glass polyalkenoate cement from it. The objective of the research described herein is to determine if incremental increases in the silver content of these glass polyalkenoate cements will increase their antibacterial efficacy against gram-positive and gram-negative bacteria using the accepted spread plate method. Four glass polyalkenoate cements were formulated; three contained increasing amounts of silver incorporated into them (cements A, B, and C, containing 0.33 mol%, 0.66 mol%, and 0.99 mol% silver, respectively) and a fourth contained no silver, which acted as a control (control cement). The handling properties of the glass polyalkenoate cements were evaluated, where working times were around 2 min and setting times ranged from 1 h 17 min to 2 h 41 min. Inductively coupled plasma atomic emission spectroscopy was employed to determine silver ion release with cement maturation for up to 14 days. The majority of silver ions were released within the first 24 h, with up to 2 mg/L cumulative ion release recorded up to 14 days. The antibacterial properties of the coatings were evaluated against Staphylococcus aureus and Pseudomonas aeruginosa bacteria. The silver-glass polyalkenoate cements exhibited antibacterial effect against both bacterial strains. The maximum inhibition zones recorded against S. aureus was 14.8 mm (SD ± 1.11) and against P. aeruginosa was 20.6 mm (SD ± 0.81). Cement B had a greater antibacterial effect compared to cement A, however, cements B and C had comparable antibacterial effects after 14 days even though cement C contained 0.33 mol% more silver than B. This indicates that by increasing the silver content in these cements, the antibacterial efficacy increases to a point, but there is a threshold where further silver ion release does not increase the antibacterial effect.

Aluminum alters NMDA receptor 1A and 2A/B expression on neonatal hippocampal neurons in rats

Background

High aluminum (Al) content in certain infant formula raises the concern of possible Al toxicity on brain development of neonates during their vulnerable period of growing. Results of in vivo study showed that Al content of brain tissues reached to 74 μM when oral intake up to 1110 μM, 10 times of that in the hi-Al infant formula.

Methods

Utilizing a cultured neuron cells in vitro model, we have assessed Al influence on neuronal specific gene expression alteration by immunoblot and immunohistochemistry and neural proliferation rate changes by MTT assay.

Results

Microscopic images showed that the neurite outgrowth of hippocampal neurons increased along with the Al dosages (37, 74 μM Al (AlCl₃)). MTT results also indicated that Al increased neural cell viability. On the other hand, the immunocytochemistry staining suggested that the protein expressions of NMDAR 1A and NMDAR 2A/B decreased with the Al dosages (p < 0.05).

Conclusion

Treated hippocampal neurons with 37 and 74 μM of Al for 14 days increased neural cell viability, but hampered NMDAR 1A and NMDAR 2A/B expressions. It was suggested that Al exposure might alter the development of hippocampal neurons in neonatal rats.

Evidence for aluminum-binding erythropoietin by size-exclusion chromatography coupled to electrothermal absorption atomic spectrometry

Erythropoietin (EPO) is a glycoprotein that stimulates erythropoiesis and is clinically used for treating anemia during chronic renal failure and for anemia in preterm infants. EPO formulations usually have elevated rates of contamination due to aluminum (Al), which is toxic to both types of patients. Size-exclusion chromatography (SEC) coupled with graphite furnace atomic absorption spectrometry (GF AAS) was employed to separate proteins and to quantify the amount of aluminum present in the elution volume corresponding to EPO and, therefore, to evaluate possible binding. Because EPO formulations contain human serum albumin (HSA), a chromatographic method was optimized for the separation of these proteins. Subsequent to the chromatographic separation, 1-mL fractions of the column effluent were collected, and the Al content in these aliquots was measured by GF AAS. EPO and HSA samples were incubated with Al for 4h at 4°C and 37°C as well as for 16 h at 4°C and 37°C. Afterwards, they were injected into the chromatographic system. These samples were also submitted to ultrafiltration (10 and 50 kDa membranes), and Al was measured in the ultrafiltrates. The results showed that Al was present in the eluent volume corresponding to the EPO peak but not in the HSA peak in the chromatograms. Temperature strengthened the interaction because the Al present in the EPO fraction was 3 times higher at 37°C compared to 4°C. Thirty-eight percent of the Al present in a 2.4 μg/mL EPO standard solution, and approximately 50% of the Al in formulation samples containing approximately 11 μg/mL EPO and either citrate or phosphate, were non-ultrafiltrable, which suggests that EPO is an effective Al acceptor in vitro.