Entry, half-life, and desferrioxamine-accelerated clearance of brain aluminum after a single (26)Al exposure

A portable front face fluorescent system for in situ detection of aluminum in flour foods

A simple and rapid method for in situ detection of aluminum in flour food was developed by using a self-made portable front face fluorescent system (PFFFS). The effects of pH, temperature, reaction time, protective agent and masking agent on the detection of Al³⁺ were investigated. The use of fluorescent probe protective agent, interfering ion masking agent, multi-point collection measurements and the working curves based on the analyte content in the real samples makes the present method have high accuracy, selectivity and reliability for in situ detection of Al³⁺ in flour foods. By comparison with the ICP-MS the accuracy and reliability of the present method were verified. The results showed that when 97 real samples were analyzed the Al³⁺ content values obtained by the present method and those obtained by ICP-MS method reached a highly significant correlation, with r ranging from 0.9747 to 0.9844. The self-made PFFFS combined with fluorescent probe does not require sample digestion, and can quickly detect Al³⁺ in flour food within 10 min. Therefore, the present method based on using FFFS has good practical application value for in-situ rapid detection of Al³⁺ in flour foods.

Green-Emissive Copper Nanocluster with Aggregation-Enhanced Emission for Selective Detection of Al3

Selective detection of Al³⁺ is of great significance both for the benefit of human health and environmental safety considerations. In this work, a sensitive and selective fluorescence assay for Al³⁺ was proposed based on the green-emissive Cu nanoclusters (Cu NCs). Different from the commonly reported works, the green emissive Cu NCs showed dual emission bands at 450 and 510 nm, attributed to the reaction product between polyvinyl pyrrolidone and ascorbic acid and the Cu core, respectively. Al³⁺ could induce the aggregation of Cu NCs by forming covalent bonds, which results in the enhancement of photoluminescence intensity. This enhancement phenomenon is rather selective to Al³⁺ , which endows the detection in real samples. These results provide new insights for the fluorescence mechanisms of metal NCs, which also provided a functional luminescent material for various applications, such as chemical sensing, bioimaging and photoelectric devices.

Urinary aluminium and its association with autism spectrum disorder in urban preschool children in Malaysia

Background

The presence of aluminium (Al) in the human body may impact brain neurodevelopment and function, and it is thought to contribute to autism spectrum disease (ASD). The main objective of this study was to assess the association between urinary Al and the development of ASD among Malaysian preschool children in the urban city of Kuala Lumpur.

Method

This was an unmatched case-control study in which children with ASD were recruited from an autism early intervention center and typically developed (TD) children were recruited from government-run nurseries and preschools. Urine samples were collected at home, assembled temporarily at study locations, and transported to the laboratory within 24 h. The Al concentration in the children's urine samples was determined using inductively coupled plasma mass spectrometry (ICP-MS).

Result

A total of 155 preschool children; 81 ASD children and 74 TD children, aged 3 to 6 years, were enlisted in the study. This study demonstrated that ASD children had significantly higher urinary Al levels than TD children (median (interquartile range (IQR): 2.89 (6.77) µg/dL versus 0.96 (2.95) µg/dL) (p < 0.001). Higher parental education level, non-Malay ethnicity, male gender, and higher urinary Al level were the significant ASD risk factors (adjusted odds ratio (aOR) >1, p < 0.05).

Conclusion

A higher urine Al level was discovered to be a significant risk factor for ASD among preschool children in the urban area of Kuala Lumpur, Malaysia.

An Overview of Vaccine Adjuvants: Current Evidence and Future Perspectives

Vaccinations are one of the most important preventive tools against infectious diseases. Over time, many different types of vaccines have been developed concerning the antigen component. Adjuvants are essential elements that increase the efficacy of vaccination practises through many different actions, especially acting as carriers, depots, and stimulators of immune responses. For many years, few adjuvants have been included in vaccines, with aluminium salts being the most commonly used adjuvant. However, recent research has focused its attention on many different new compounds with effective adjuvant properties and improved safety. Modern technologies such as nanotechnologies and molecular biology have forcefully entered the production processes of both antigen and adjuvant components, thereby improving vaccine efficacy. Microparticles, emulsions, and immune stimulators are currently in the spotlight for their huge potential in vaccine production. Although studies have reported some potential side effects of vaccine adjuvants such as the recently recognised ASIA syndrome, the huge worth of vaccines remains unquestionable. Indeed, the recent COVID-19 pandemic has highlighted the importance of vaccines, especially in regard to managing future potential pandemics. In this field, research into adjuvants could play a leading role in the production of increasingly effective vaccines.

Physiology-based toxicokinetic modelling of aluminium in rat and man

A sufficient quantitative understanding of aluminium (Al) toxicokinetics (TK) in man is still lacking, although highly desirable for risk assessment of Al exposure. Baseline exposure and the risk of contamination severely limit the feasibility of TK studies administering the naturally occurring isotope 27Al, both in animals and man. These limitations are absent in studies with 26Al as a tracer, but tissue data are limited to animal studies. A TK model capable of inter-species translation to make valid predictions of Al levels in humans-especially in toxicological relevant tissues like bone and brain-is urgently needed. Here, we present: (i) a curated dataset which comprises all eligible studies with single doses of 26Al tracer administered as citrate or chloride salts orally and/or intravenously to rats and humans, including ultra-long-term kinetic profiles for plasma, blood, liver, spleen, muscle, bone, brain, kidney, and urine up to 150 weeks; and (ii) the development of a physiology-based (PB) model for Al TK after intravenous and oral administration of aqueous Al citrate and Al chloride solutions in rats and humans. Based on the comprehensive curated 26Al dataset, we estimated substance-dependent parameters within a non-linear mixed-effect modelling context. The model fitted the heterogeneous 26Al data very well and was successfully validated against datasets in rats and humans. The presented PBTK model for Al, based on the most extensive and diverse dataset of Al exposure to date, constitutes a major advancement in the field, thereby paving the way towards a more quantitative risk assessment in humans.

Neurotoxic effects of combined exposures to aluminum and mercury in early life (infancy)

Aluminum and mercury are environmentally ubiquitous. Individually they are both neurotoxic elements with shared neuro-pathogenic pathways: oxidative stress, altered neurotransmission, and disruption of the neuroendocrine and immune systems. In the infant, Al and Hg differ in type of exposure, absorption, distribution (brain access), and metabolism. In environmentally associated exposure (breast milk and infant formulas) their co-occurrences fluctuate randomly, but in Thimerosal-containing vaccines (TCVs) they occur combined in a proprietary ratio; in these cases, low-doses of Thimerosal-ethylmercury (EtHg) and adjuvant-Al present the most widespread binary mixture in less developed countries. Although experimental studies at low doses of the binary Hg and Al mixture are rare, when studied individually they have been shown to affect neurological outcomes negatively. In invitro systems, comparative neurotoxicity between Al and Hg varies in relation to the measured parameters but seems less for Al than for Hg. While neurotoxicity of environmental Hg (mainly fish methyl-Hg, MeHg) is associated with neurobehavioral outcomes in children, environmental Al is not associated, except in certain clinical conditions. Therefore, the issues of their neurotoxic effects (singly or combined) are discussed. In the infant (up to six months) the organic-Hg and Al body burdens from a full TCV schedule are estimated to reach levels higher than that originating from breastfeeding or from high aluminum soy-based formulas. Despite worldwide exposure to both Al and Hg (inorganic Hg, MeHg, and Thimerosal/EtHg), our knowledge on this combined exposure is insufficient to predict their combined neurotoxic effects (and with other co-occurring neurotoxicants).

Al (III) metal augment thermal aggregation and fibrillation in protein: Role of metal toxicity in neurological diseases

Protein fibrillation is a leading cause of innumerable neurodegenerative diseases. The exact underlying mechanism associated with the formation of fibrils is yet to be known. Recently, the role of metal ions resulting into fibrillation of proteins has gained attention of the scientific community. In this piece of work, we have investigated the effect of the aluminum (Al) metal ion on the kinetics of aggregation of bovine serum albumin (BSA) protein under physiological conditions by employing several biophysical and microscopic techniques. Quenching of tryptophan fluorescence was observed along with 9 nm blue shift, demonstrating BSA becomes more hydrophobic during unfolding pathway of thermal denaturation. Moreover, ANS (8-Anilino-1-naphthalene sulfonic acid) binding shows quenching in fluorescence intensity with increasing time of incubation at 65 °C, suggesting unfolding leading to the disruption of hydrophobic patches in BSA. Besides, Thioflavin T intensity indicated a significant acceleration in BSA fibrillation at a ratio of 1:1 and 1:2 of BSA and Al (III) metal ion respectively. In addition, circular dichroism (CD) spectroscopy study revealed the transition of BSA from α-helical conformation to the β-sheet rich structure. Molecular docking analysis demonstrated significant binding affinity (-1.2 kcal/mol) of Al (III) with BSA involving Phe501, Phe506, Val575, Thr578, Gln579, Leu531 residues. Transmission electron microscopy (TEM) reaffirm augmentation of thermal-induced BSA fibril formation in the presence of Al (III) metal ions. This study highlights the metal chelating potency as the possible therapeutic target for neurological diseases.

Aluminum reproductive toxicity: a summary and interpretation of scientific reports

Publications addressing aluminum (Al)-induced reproductive toxicity were reviewed. Key details were compiled in summary tables. Approximate systemic Al exposure, a measure of bioavailability, was calculated for each exposure, based on the Al percentage in the dosed Al species, Al bioavailability, and absorption time course reports for the exposure route. This was limited to laboratory animal studies because no controlled-exposure human studies were found. Intended Al exposure was compared to unintended dietary Al exposure. The considerable and variable Al content of laboratory animal diets creates uncertainty about reproductive function in the absence of Al. Aluminum-induced reproductive toxicity in female mice and rats was evident after exposure to ≥25-fold the amount of Al consumed in the diet. Generally, the additional daily Al systemic exposure of studies that reported statistically significant results was greater than 100-fold above the typical human daily Al dietary consumption equivalent. Male reproductive endpoints were significantly affected after exposure to lower levels of Al than females. Increased Al intake increased fetus, placenta, and testes Al concentrations, to a greater extent in the placenta than fetus, and, in some cases, more in the testes than placenta. An adverse outcome pathway (AOP) was constructed for males based on the results of the reviewed studies. The proposed AOP includes oxidative stress as the molecular initiating event and increased malondialdehyde, DNA and spermatozoal damage, and decreased blood testosterone and sperm count as subsequent key events. Recommendations for the design of future studies of reproductive outcomes following exposure to Al are provided.

Aluminum and aluminum oxide nanomaterials uptake after oral exposure - a comparative study

The knowledge about a potential in vivo uptake and subsequent toxicological effects of aluminum (Al), especially in the nanoparticulate form, is still limited. This paper focuses on a three day oral gavage study with three different Al species in Sprague Dawley rats. The Al amount was investigated in major organs in order to determine the oral bioavailability and distribution. Al-containing nanoparticles (NMs composed of Al0 and aluminum oxide (Al2O3)) were administered at three different concentrations and soluble aluminum chloride (AlCl3·6H2O) was used as a reference control at one concentration. A microwave assisted acid digestion approach followed by inductively coupled plasma mass spectrometry (ICP-MS) analysis was developed to analyse the Al burden of individual organs. Special attention was paid on how the sample matrix affected the calibration procedure. After 3 days exposure, AlCl3·6H2O treated animals showed high Al levels in liver and intestine, while upon treatment with Al0 NMs significant amounts of Al were detected only in the latter. In contrast, following Al2O3 NMs treatment, Al was detected in all investigated organs with particular high concentrations in the spleen. A rapid absorption and systemic distribution of all three Al forms tested were found after 3-day oral exposure. The identified differences between Al0 and Al2O3 NMs point out that both, particle shape and surface composition could be key factors for Al biodistribution and accumulation.

Aluminum affects neural phenotype determination of embryonic neural progenitor cells

Aluminum (Al) is a neurotoxin and is associated with the etiology of neurodegenerative diseases, such as Alzheimer's disease (AD). The Al-free ion (Al³⁺) is the biologically reactive and toxic form. However, the underlying mechanisms of Al toxicity in the brain remain unclear. Here, we evaluated the effects of Al³⁺ (in the chloride form-AlCl₃) at different concentrations (0.1-100 µM) on the morphology, proliferation, apoptosis, migration and differentiation of neural progenitor cells (NPCs) isolated from embryonic telencephalons, cultured as neurospheres. Our results reveal that Al³⁺ at 100 µM reduced the number and diameter of neurospheres. Cell cycle analysis showed that Al³⁺ had a decisive function in proliferation inhibition of NPCs during neural differentiation and induced apoptosis on neurospheres. In addition, 1 µM Al³⁺ resulted in deleterious effects on neural phenotype determination. Flow cytometry and immunocytochemistry analysis showed that Al³⁺ promoted a decrease in immature neuronal marker β3-tubulin expression and an increase in co-expression of the NPC marker nestin and glial fibrillary acidic protein. Thus, our findings indicate that Al³⁺ caused cellular damage and reduced proliferation and migration, resulting in global inhibition of NPC differentiation and neurogenesis.

Dendritic spine loss caused by AlCl3 is associated with inhibition of the Rac 1/cofilin signaling pathway

Aluminum (Al) has neurotoxicity that can result in cognitive dysfunction. Hippocampal dendritic spine loss is a pathological characteristic of cognitive dysfunction. Our previous study reported that Al exposure caused dendritic spine loss in the hippocampus, but the underlying mechanism remains unclear. In this study, rats were orally administered 50, 150 or 450 mg/kg of AlCl₃ for 90 days. The dendritic spine density of the CA1 and DG regions was detected by Golgi-Cox staining. The F-actin/G-actin ratio, the expression of drebrin A and the components of the Rac 1/cofilin pathway were measured in the hippocampus. The results obtained showed that AlCl₃ caused dendritic spine loss and decreased the F-actin/G-actin ratio. In addition, it was found that AlCl₃ downregulated the expression of Rac 1, p-PAK, p-LIMK, p-cofilin and drebrin A and upregulated cofilin expression. Altogether, these results demonstrated that Al inactivated the Rac 1/cofilin pathway by inhibiting the phosphorylation of cofilin and the polymerization of F-actin, resulting in dendritic spine loss in the hippocampus.

The Effect of Aluminum Exposure on Reproductive Ability in the Bank Vole (Myodes glareolus)

Human impact on the environment is steadily increasing the amounts of aluminum in the ecosystems. This element accumulates in plants and water, potentially exposing herbivores to its harmful effect. In heavily polluted sites, a decrease in the density of small rodent populations has been observed. This decline may be caused by many factors, including decreased fertility. The aim of the presented research was to determine how aluminum, administered at concentrations similar to those recorded in industrial districts (Al I = 3 mg/l, Al II = 200 mg/l), affects the reproductive abilities of small rodents. As the indicators of reproductive abilities, body weight, weight of the testes and accessory sex glands of males, and uterus weight of females were estimated. In females, the number of matured follicles (types 6, 7, and 8) was analyzed, while in males, the quantity and quality (matured, viable, swollen, motile, head abnormalities) of epididymal sperm cells were assessed. Moreover, the development of testes, measured by spermatogenic index, was determined. The model species was the bank vole. Our results have proven that aluminum impairs adult individuals' reproductive abilities by decreasing the quality and quantity of sperm cells and by causing morphologically abnormal development of the gonads. However, no difference in male organometric parameters was found, and only in females treated with 3 mg/l Al, the uterus weight was higher than control. No differences were found in the total number of matured follicles. These results suggest that the decline in rodent numbers in industrial districts is due, at least in part, to poorer males' reproductive abilities, resulting from exposure to aluminum contamination.

Neurodegeneration Induced by Metals in Caenorhabditis elegans

Metals are a component of a variety of ecosystems and organisms. They can generally be divided into essential and nonessential metals. The essential metals are involved in physiological processes once the deficiency of these metals has been associated with diseases. Although iron, manganese, copper, and zinc are important for life, it has been evidenced that they are also involved in neuronal damage in many neurodegenerative disorders. Nonessential metals, which are metals without physiological functions, are present in trace or higher levels in living organisms. Occupational, environmental, or deliberate exposures to lead, mercury, aluminum, and cadmium are clearly correlated with the increase of toxicity and varied kinds of pathological situations. Actually, the field of neurotoxicology needs to satisfy two opposing demands: the testing of a growing list of chemicals and resource limitations and ethical concerns associated with testing using traditional mammalian species. Toxicological assays using alternative animal models may relieve some of this pressure by allowing testing of more compounds while reducing expenses and using fewer mammals. The nervous system is by far the more complex system in C. elegans. Almost a third of their cells are neurons (302 neurons versus 959 cells in adult hermaphrodite). It initially underwent extensive development as a model organism in order to study the nervous system, and its neuronal lineage and the complete wiring diagram of its nervous system are stereotyped and fully described. The neurotransmission systems are phylogenetically conserved from nematodes to vertebrates, which allows for findings from C. elegans to be extrapolated and further confirmed in vertebrate systems. Different strains of C. elegans offer a new perspective on neurodegenerative processes. Some genes have been found to be related to neurodegeneration induced by metals. Studying these interactions may be an effective tool to slow neuronal loss and deterioration.

Aluminum exposure decreases dopamine D1 and D2 receptor expression in mouse brain

Aluminum (Al) has been identified as a potential contributing factor in the etiology of several neurodegenerative disorders, but data regarding specific effects on neurotransduction, especially on dopaminergic neurotransduction, are lacking. The objective of this study was to determine the extent of expressional alterations in dopamine receptors (DRs) in two dopaminergic subtypes, D1 and D2, in low and high dose Al-treated mice. After administration of Al (four intraperitoneal injections of 30 or 60 mg/kg AlCl3·6H2O at 2 h intervals), expression of the dopamine D1-like and D2-like receptors (DRD1, DRD2) was examined in the cortex and striatum of mouse brain at bregma levels of 1.10, -0.10 and -1.34 mm. In the cortex, Al treatment decreased densities of DRD1 and DRD2 in a dose-dependent manner at all three bregma levels, especially in the high-dose Al group. Similarly, DRD1 and DRD2 expression in the striatum also exhibited dose dependency and statistically significant decreases were seen in the high-dose group, except in the striatum at bregma level - 1.34. These findings suggest that DR in the caudal striatum is more resistant to the effects of Al exposure than DR in the cortex or rostral striatum. In addition, our results suggest that disturbance of dopaminergic neurotransmission mediated by DRD1 and/or DRD2 may be involved in the pathogenesis of Al neurotoxicity. Human & Experimental Toxicology (2007) 26, 741 — 746

Human and Environmental Dangers Posed by Ongoing Global Tropospheric Aerosolized Particulates for Weather Modification

BACKGROUND

U.S. military perception of nuclear warfare led to countless unethical nuclear experiments performed on unsuspecting individuals without their informed consent. As evidenced here, subsequent perception of weather warfare has led to exposing millions of unsuspecting individuals to toxic coal fly ash with no public disclosure, no informed consent, and no health warnings.

METHODS

Three methods were used: (1) comparison of eight elements analyzed in rainwater samples, thought to have leached from aerosolized coal fly ash, with corresponding coal fly ash laboratory leachate; (2) comparison of 14 elements analyzed in air filter dust with corresponding elements in coal fly ash; and (3) comparison of 23 elements analyzed in fibrous mesh found after snow melted with corresponding elements in coal fly ash.

RESULTS

The rainwater element ratios show that the aerial particulate matter has essentially the same water-leach characteristics as coal fly ash. The air filter dust element ratios occur in the same range of compositions as coal fly ash, as do element ratios in fibrous mesh found on grass after snow melted. The fibrous mesh provides an inferred direct connection with the aerosolizing jet aircraft via coal fly ash association with the jet combustion environment.

CONCLUSION

Strong evidence for the correctness of the hypothesis: coal fly ash is likely the aerosolized particulate emplaced in the troposphere for geoengineering, weather modification, and/or climate alteration purposes. The documented public health associations for ≤2.5 μm particulate pollution are also applicable to aerosolized coal fly ash. The ability of coal fly ash to release aluminum in a chemically mobile form upon exposure to water or body moisture has potentially grave human and environmental consequences over a broad spectrum, including implications for neurological diseases and biota debilitation. The ability of coal fly ash to release heavy metals and radioactive elements upon exposure to body moisture has potentially grave human health implications including cancer, cardiovascular disease, diabetes, respiratory diseases, reduced male fertility, and stroke. The fibrous mesh data admit the possibility of environmentally disastrous formation of methylmercury and ozone-depleting chlorinated-fluorinated hydrocarbons in jet exhaust. Geophysical implications include atmospheric warming and rainfall retardation.

Low levels of aluminum can lead to behavioral and morphological changes associated with Alzheimer's disease and age-related neurodegeneration

Aluminum (Al) is a very common component of the earth's mineral composition. It is not essential element for life and is a constituent of rather inert minerals. Therefore, it has often been regarded as not presenting a significant health hazard. As a result, aluminum-containing agents been used in the preparation of many foodstuffs processing steps and also in elimination of particulate organic matter from water. More recently, the reduced pH of bodies of water resulting from acid rain has led to mobilization of aluminum-containing minerals into a more soluble form, and these have thus entered residential drinking water resources. By this means, the body burden of aluminum in humans has increased. Epidemiological and experimental findings indicate that aluminum is not as harmless as was previously thought, and that aluminum may contribute to the inception and advancement of Alzheimer's disease. Epidemiological data is reinforced by indications that aluminum exposure can result in excess inflammatory activity within the brain. Activation of the immune system not initiated by an infectious agent, typifies the aging brain and is even more augmented in several neurodegenerative diseases. The origin of most age-related neurological disorders is generally not known but as they are largely not of genetic derivation, their development is likely triggered by unknown environmental factors. There is a growing and consistent body of evidence that points to aluminum as being one such significant influence. Evidence is presented that reinforces the likelihood that aluminum is a factor speeding the rate of brain aging. Such acceleration would inevitably enlarge the incidence of age-related neurological diseases.

Evidence of Coal-Fly-Ash Toxic Chemical Geoengineering in the Troposphere: Consequences for Public Health

The widespread, intentional and increasingly frequent chemical emplacement in the troposphere has gone unidentified and unremarked in the scientific literature for years. The author presents evidence that toxic coal combustion fly ash is the most likely aerosolized particulate sprayed by tanker-jets for geoengineering, weather-modification and climate-modification purposes and describes some of the multifold consequences on public health. Two methods are employed: (1) Comparison of 8 elements analyzed in rainwater, leached from aerosolized particulates, with corresponding elements leached into water from coal fly ash in published laboratory experiments, and (2) Comparison of 14 elements analyzed in dust collected outdoors on a high-efficiency particulate air (HEPA) filter with corresponding elements analyzed in un-leached coal fly ash material. The results show: (1) the assemblage of elements in rainwater and in the corresponding experimental leachate are essentially identical. At a 99% confidence interval, they have identical means (T-test) and identical variances (F-test); and (2) the assemblage of elements in the HEPA dust and in the corresponding average un-leached coal fly ash are likewise essentially identical. The consequences on public health are profound, including exposure to a variety of toxic heavy metals, radioactive elements, and neurologically-implicated chemically mobile aluminum released by body moisture in situ after inhalation or through transdermal induction.

Mangiferin ameliorates aluminium chloride-induced cognitive dysfunction via alleviation of hippocampal oxido-nitrosative stress, proinflammatory cytokines and acetylcholinesterase level

Mangiferin is a phytochemical primarily present in the stem, leaves and bark of Mangifera indica. It offers neuroprotection mainly through inhibition of oxidative stress, and decreasing proinflammatory cytokines level in the brain. Aluminium has been reported to cause oxidative stress-associated damage in the brain. In the present investigation, protective effect of mangiferin against aluminium chloride (AlCl3)-induced neurotoxicity and cognitive impairment was studied in male Swiss albino mice. AlCl3 (100 mg/kg) was administered once daily through oral gavage for 42 days. Mangiferin (20 and 40 mg/kg, p.o.) was given to mice for last 21 days of the study. We found cognitive dysfunction in AlCl3-treated group, which was assessed by Morris water maze test, and novel object recognition test. AlCl3-treated group showed elevated level of oxidative stress markers, proinflammatory cytokines level and lowered hippocampal brain-derived neurotrophic factor (BDNF) content. Mangiferin (40 mg/kg) prevented the cognitive deficits, hippocampal BDNF depletion, and biochemical anomalies induced by AlCl3-treatment. In conclusion, our data demonstrated that mangiferin offers neuroprotection in AlCl3-induced neurotoxicity and it may be a potential therapeutic approach in the treatment of oxido-nitrosative stress and inflammation-associated neurotoxicity.

Aluminium in allergen-specific subcutaneous immunotherapy--a German perspective

We are living in an "aluminium age" with increasing bioavailability of the metal for approximately 125 years, contributing significantly to the aluminium body burden of humans. Over the course of life, aluminium accumulates and is stored predominantly in the lungs, bones, liver, kidneys and brain. The toxicity of aluminium in humans is briefly summarised, highlighting links and possible causal relationships between a high aluminium body burden and a number of neurological disorders and disease states. Aluminium salts have been used as depot-adjuvants successfully in essential prophylactic vaccinations for almost 100 years, with a convincing positive benefit-risk assessment which remains unchanged. However, allergen-specific immunotherapy commonly consists of administering a long-course programme of subcutaneous injections using preparations of relevant allergens. Regulatory authorities currently set aluminium limits for vaccines per dose, rather than per treatment course. Unlike prophylactic vaccinations, numerous injections with higher proportions of aluminium-adjuvant per injection are applied in subcutaneous immunotherapy (SCIT) and will significantly contribute to a higher cumulative life dose of aluminium. While the human body may cope robustly with a daily aluminium overload from the environment, regulatory cumulative threshold values in immunotherapy need further addressing. Based on the current literature, predisposing an individual to an unusually high level of aluminium, such as through subcutaneous immunotherapy, has the potential to form focal accumulations in the body with the propensity to exert forms of toxicity. Particularly in relation to longer-term health effects, the safety of aluminium adjuvants in immunotherapy remains unchallenged by health authorities - evoking the need for more consideration, guidance, and transparency on what is known and not known about its safety in long-course therapy and what measures can be taken to prevent or minimise its risks. The possibility of providing an effective means of measuring aluminium accumulation in patients undergoing long-term SCIT treatment as well as reducing their aluminium body burden is discussed.

Serum aluminum levels in dialysis patients after sclerotherapy of internal hemorrhoids with aluminum potassium sulfate and tannic acid

PURPOSE

Aluminum potassium sulfate and tannic acid (ALTA) is an effective sclerosing agent for internal hemorrhoids. However, it is contraindicated for patients with chronic renal failure on dialysis, because the aluminum in ALTA can cause aluminum encephalopathy when it is not excreted effectively. We conducted this study to measure the serum aluminum concentrations and observe for symptoms relating to aluminum encephalopathy in dialysis patients after ALTA therapy.

METHODS

Ten dialysis patients underwent ALTA therapy for hemorrhoids. We measured their serum aluminum concentrations and observed them for possible symptoms of aluminum encephalopathy.

RESULTS

The total injection volume of ALTA solution was 31 mL (24-37). The median serum aluminum concentration before ALTA therapy was 9 μg/L, which increased to 741, 377, and 103 μg/L, respectively, 1 h, 1 day, and 1 week after ALTA therapy. These levels decreased rapidly, to 33 μg/L by 1 month and 11 μg/L by 3 months after ALTA therapy. No patient suffered symptoms related to aluminum encephalopathy.

CONCLUSIONS

Although the aluminum concentrations increased temporarily after ALTA therapy, dialysis patients with levels below 150 μg/L by 1 week and thereafter are considered to be at low risk of the development of aluminum encephalopathy.

Prolonged exposure to low levels of aluminum leads to changes associated with brain aging and neurodegeneration

Aluminum is one of the most common metal elements in the earth's crust. It is not an essential element for life and has commonly been thought of as a rather inert and insoluble mineral. Therefore, it has often been regarded as not posing a significant health hazard. In consequence, aluminum-containing agents been used in many food processing steps and also in removal by flocculation of particulate organic matter from water. In recent years, acid rain has tended to mobilize aluminum-containing minerals into a more soluble form, ionic Al(3+), which has found their way into many reservoirs that constitute residential drinking water resources. As a result, the human body burden of aluminum has increased. Epidemiological studies suggest that aluminum may not be as innocuous as was previously thought and that aluminum may actively promote the onset and progression of Alzheimer's disease. Epidemiological data is strengthened by experimental evidence of aluminum exposure leading to excess inflammatory activity within the brain. Such apparently irrelevant immune activity unprovoked by an exogenous infectious agent characterizes the aging brain and is even more pronounced in several neurodegenerative diseases. The causation of most of these age-related neurological disorders is not understood but since they are generally not genetic, one must assume that their development is underlain by unknown environmental factors. There is an increasing and coherent body of evidence that implicates aluminum as being one such significant factor. Evidence is outlined supporting the concept of aluminum's involvement in hastening brain aging. This acceleration would then inevitably lead to increased incidence of specific age-related neurological diseases.

Searching for new aluminium chelating agents: a family of hydroxypyrone ligands

Attention is devoted to the role of chelating agents in the treatment of aluminium related diseases. In fact, in spite of the efforts that have drastically reduced the occurrence of aluminium dialysis diseases, they so far constitute a cause of great medical concern. The use of chelating agents for iron and aluminium in different clinical applications has found increasing attention in the last thirty years. With the aim of designing new chelators, we synthesized a series of kojic acid derivatives containing two kojic units joined by different linkers. A huge advantage of these molecules is that they are cheap and easy to produce. Previous works on complex formation equilibria of a first group of these ligands with iron and aluminium highlighted extremely good pMe values and gave evidence of the ability to scavenge iron from inside cells. On these bases a second set of bis-kojic ligands, whose linkers between the kojic chelating moieties are differentiated both in terms of type and size, has been designed, synthesized and characterized. The aluminium(III) complex formation equilibria studied by potentiometry, electrospray ionization mass spectroscopy (ESI-MS), quantum-mechanical calculations and (1)H NMR spectroscopy are here described and discussed, and the structural characterization of one of these new ligands is presented. The in vivo studies show that these new bis-kojic derivatives induce faster clearance from main organs as compared with the monomeric analog.

Protective effects of copper against aluminum toxicity on acetylcholinesterase and catecholamine contents of different regions of rat's brain

The probable protective effects of copper on the acetylcholinesterase activity and the catecholamine levels in cerebellum, cortex and mid-brain of rat, which was intoxicated by aluminum, were studied during short and long terms. In this respect, male Wistar rats weighing 200-250 g were received daily intraperitoneal doses of aluminum, copper and also combined doses of both metals for 15 days (Al 10 mg kg(-1) BW and Cu 1 mg kg(-1) BW), 30 days (Al 5 mg kg(-1) BW and Cu 0.5 mg kg(-1) BW) and 60 days (Al 1 mg kg(-1) BW and Cu 0.1 mg kg(-1) BW), respectively. The results obtained from the short period of exposure (15 days) showed that aluminum produced significant (P < 0.05) decreases in the acetylcholinesterase activity by 24.14, 23.30 and 25.81 %. Similarly, the catecholamine levels were reduced by 10.69, 12.25 and 12.64 % in cerebellum, cortex and mid-brain, respectively. Treatment with copper increases both acetylcholinesterase activity and catecholamine contents of cerebellum, cortex and mid-brain. Simultaneous injection of copper and aluminum increased both acetylcholinesterase activity and catecholamine contents in all three parts of rat brain when compared to aluminum-treated group. Same results were also observed following 30 and 60 days of exposures. In overall, it has been found that copper may have a protective-like ability to hinder aluminum toxicity in the brain.

Different approaches to the study of chelating agents for iron and aluminium overload pathologies

Our objective is to illustrate the activity of the groups operating in Italy involved in identification and study of new chelating agents, mainly intended for treatment of human pathology correlated with metal overload. The objective of "chelation therapy" is removal of toxic metal ions from the human body or attenuation of their toxicity by transforming them into less toxic compounds or by dislocating them from the site at which they exert a toxic action. Because most of this research activity is related to chelating agents for iron and aluminium, diseases related to these two metal ions are briefly treated. Iron overload is the most common metal toxicity disease worldwide. The toxicity of aluminium in dialysis patients was a serious problem for haemodialysis units in the seventies and eighties of the last century. In particular, this review focuses on research performed by the group at Cagliari and Ferrara, and by that at Padova. The former is studying, above all, bisphosphonate and kojic acid derivatives, and the latter is investigating 3,4-hydroxypyridinecarboxylic acids with differently substituted pyridinic rings.

Towards the prevention of potential aluminum toxic effects and an effective treatment for Alzheimer's disease

In 1991, treatment with low dose intramuscular desferrioxamine (DFO), a trivalent chelator that can remove excessive iron and/or aluminum from the body, was reported to slow the progression of Alzheimer's disease (AD) by a factor of two. Twenty years later this promising trial has not been followed up and why this treatment worked still is not clear. In this critical interdisciplinary review, we provide an overview of the complexities of AD and involvement of metal ions, and revisit the neglected DFO trial. We discuss research done by us and others that is helping to explain involvement of metal ion catalyzed production of reactive oxygen species in the pathogenesis of AD, and emerging strategies for inhibition of metal-ion toxicity. Highlighted are insights to be considered in the quests to prevent potentially toxic effects of aluminum toxicity and prevention and intervention in AD.

Aluminum does not enhance beta-amyloid toxicity in rat hippocampal cultures

A number of environmental factors have been implicated in neurodegenerative disorders, including metallotoxins such as aluminum (Al). In the present study, the toxicity of Al-quinate (AlQ), a well-characterized Al complex, was investigated in primary rat hippocampal cultures in comparison to inorganic Al (Al-S). AlQ was significantly less toxic than Al-S during both short- (3h) and long-term (24h) incubations. The neuroprotective properties of quinic acid (which constitutes the quinate moiety of AlQ) against short-term incubations with Al-S were subsequently assessed, and the organic compound was found to provide full protection, comparable to synthetic metal chelating agents desferrioxamine and clioquinol. Finally, potential synergistic actions between Al (AlQ and Al-S) and beta-amyloid (Abeta) were investigated. Neither Al form appeared to enhance Abeta toxicity, in fact, AlQ significantly reduced Abeta toxicity. Collectively, this study highlights further the impact of structural features and physiological ligands of metal complexes on toxicity profiles, and reveals promising properties of quinic acid as a metal chelator. Despite previous reports suggesting synergistic toxicity between Al and Abeta, we could not identify such a mechanism in our investigation.

The neurotoxicity of environmental aluminum is still an issue

Evidence for the neurotoxicity of extended exposure to low levels of aluminum salts is described using an animal model treated with aluminum at low levels reflecting those found in some water supplies. Emphasis is given to the potential role of aluminum in acceleration and promotion of some indices characteristic of brain aging. These hallmarks include the appearance of excess levels of inflammation in specific brain areas. Aluminum salts can increase levels of glial activation, inflammatory cytokines and amyloid precursor protein within the brain. Both normal brain aging and to a greater extent, Alzheimer's disease are associated with elevated basal levels of markers for inflammation. These are not attributable to obvious exogenous stimuli and may reflect the lifespan history of the organism's immune responses. It is possible that aluminum salts can act as a subtle promoter of such apparently unprovoked responses.

Aluminum Toxicity Following IV Use of Oral Methadone Solution

BACKGROUND

Aluminum toxicity has been reported in renal failure patients exposed to aluminum-contaminated dialysate and oral phosphate binders. We report a case of significant aluminum toxicity in a non-hemodialysis patient.

CASE REPORT

A 43-year-old male IV drug user presented to the hospital with a seizure disorder of recent onset, progressive cognitive decline, ataxia, and dysarthria. The serum aluminum concentration was 180 micrograms/L (6.65 micromol/L). For 3 to 4 years prior, the patient had injected 'cooked' oral methadone. The methadone solution was heated in an aluminum pot to reduce the volume and then injected intravenously (IV). He was treated with IV deferoxamine over 9 months until he failed to return. Serum aluminum level after 9 months of treatment was 64.5 microgram/L (2.39 micromol/L). Neurological symptoms were partially improved.

CONCLUSION

Chronic IV injection of oral methadone solution heated in an aluminum-based cooking utensil may result in significant aluminum toxicity.

Aluminum complexing enhances amyloid β protein penetration of blood–brain barrier

A significant co-morbidity of Alzheimer's disease and cerebrovascular impairment suggests that cerebrovascular dysregulation is an important feature of dementia. Amyloid beta protein (Abeta), a relevant risk factor in Alzheimer's disease, has neurotoxic properties and is thought to play a critical role in the cognitive impairments. Previously, we demonstrated that the 42mer of Abeta (Abeta42) complexed with aluminum (Al-Abeta42) is much more cytotoxic than non-complexed Abeta42. The level of Abeta in the brain is a balance between synthesis, degradation, and fluxes across the blood-brain barrier (BBB). In the present paper, we determined whether complexing with aluminum affected the ability of radioactively iodinated Abeta to cross the in vivo BBB. We found that the rates of uptake of Al-Abeta42 and Abeta42 were similar, but that Al-Abeta42 was sequestered by brain endothelial cells much less than Abeta42 and so more readily entered the parenchymal space of the brain. Al-Abeta42 also had a longer half-life in blood and had increased permeation at the striatum and thalamus. Brain-to-blood transport was similar for Al-Abeta42 and Abeta42. In conclusion, complexing with aluminum affects some aspects of blood-to-brain permeability so that Al-Abeta42 would have more ready access to brain cells than Abeta42.