Aluminium hypothesis lives

Clinical Outcomes of the Deleterious Effects of Aluminum on Neuro-Cognition, Inflammation, and Health: A Review

Introduction: In the scenario of metal toxicity, aluminum (Al) stands out as a ubiquitous type of metal that can be combined with other elements and form different compounds. Al is widely used daily as an adjuvant in vaccines, antacids, food additives (as components of AI-containing food additives), skin care products, cosmetics, and kitchenware, and can be an element or contaminant present in our daily life. Objective: To present a review of the main deleterious effects of Al on human health. Methods: The search was carried out from September 2022 to February 2023 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases, using scientific articles from 2012 to 2023. The quality of the studies was based on the GRADE instrument, and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusions: A total of 115 files were search returned. Further, 95 articles were evaluated, and 44 were included in this review. Based on the results, measuring Al's relevance to health is essential in medicine. Several studies have demonstrated clinical outcomes and metabolic alterations with Al exposure. The tolerable weekly intake established by the European Food Safety Authority (EFSA) of 1 mg Al/kg body weight can be achieved through dietary exposure alone. Proven neurotoxicity in humans is the critical adverse effect of Al. A carcinogenic effect of Al has not been proven so far. Preventive medicine advocates that exposure to Al should be kept as low as possible. Chelating agents, such as calcium disodium ethylene diamine tetraacetic acid and deferoxamine, are options for acute poisoning, and monomethysilanetriol supplementation may be a long-term strategy with chelation potential. Further studies are needed to assess the impacts of Al on human health.

Treatment of peripubertal children after renal transplantation (RTX) with recombinant human growth hormone: auxological data and effects on insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3) during 24 months

OBJECTIVE

To evaluate growth and endocrine parameters in RTX children with GH treatment during 24 months.

SUBJECTS

18 children (13 boys), age 13.1 yr (8.0-16.6), bone age 10.1 yr (5.4-15.3). Patients were 2.8 yr (0.5-7.5) after RTX and had immunosuppressive therapy, prednisone 0.16 mg/kg/d (0.08-0.68).

METHODS

GH (4 IU/m2/day s.c.) was given and patients were seen every 3 months for evaluation of height, height velocity, bone age, and hormone parameters. Serum IGF-I was determined by RIA, IGFBP-3 by RIA and Western ligand blotting (WLB). Renal function and adverse effects (GFR, glucose tolerance, rejection episodes) were monitored.

RESULTS

Height (+1 SDS) and height velocity (+2.2 SDS) increased significantly during 24 months GH treatment, but delta BA/delta CA was 1.7 and 1.5 during the first and second treatment year, respectively, and all patients entered puberty during the treatment period. GFR decreased slightly during 2 yr (p = 0.048), two patients had chronic rejection and GH therapy was terminated in one patient because of glucose intolerance. The ratio IGF-I/IGFBP-3 rose during the first year (p = 0.002) indicating more bioavailable IGF-I. IGFBP-3 determined by WLB was decreased, but IGFBP-1, -2 and -4 were elevated as compared to a standard.

CONCLUSIONS

GH treatment increased height and growth rate in children after RTX. This may be due to significant changes in IGF-I and IGFBP-3 relationship. However, bone maturation was also accelerated thus diminishing height potential. From month 12 to 24 a continuous decrease of IGF-I was observed. There was a slight but significant deterioration of graft function. Adverse events that led to termination of GH therapy were observed in 3 of 18 patients.

Selective modulation of GABAA receptors by aluminum

Aluminum has been implicated in several neurodegenerative conditions including Alzheimer's disease. Because the mammalian olfactory system has an unusual capacity for the uptake and transneuronal spread of inhaled substances such as aluminum, whole cell recording techniques were used to examine the actions of aluminum on basic membrane properties and amino acid receptors on rat olfactory bulb mitral/tufted (M/T) neurons in culture. Aluminum had little direct effects on M/T neurons. Aluminum (100 microM) did not evoke a membrane current or alter action-potential shape or duration. Aluminum also had no marked effects on the family of voltage-gated membrane currents evoked by a series of 10-mV, 50-ms depolarizing steps. However, aluminum dramatically potentiated the current evoked by 30 microM gamma-aminobutyric acid (GABA) at concentrations <100 microM. Conversely, higher concentrations of aluminum blocked the GABA-evoked current. The effects of aluminum on GABA-evoked currents were not voltage dependent. Aluminum (100 microM) equally potentiated both inward currents at -30 mV and outward currents at + 30 mV. At 300 microM, aluminum blocked both inward and outward currents to a similar extent. In some neurons, aluminum only blocked the current and potentiation was not observed. The biphasic action of aluminum on GABA-evoked currents suggests separate binding sites: a high-affinity potentiating site and a low-affinity inhibiting site. Despite its effects on GABA-evoked currents, aluminum did not alter membrane currents evoked by glutamate, N-methyl-D-aspartate, kainate, or glycine. Aluminum also did not reduce spontaneous excitatory synaptic activity, suggesting little, if any, effect on glutamate release. Although a causal role for aluminum in Alzheimer's disease and other neuropathological conditions remains controversial, it is clear that elevated aluminum concentrations in the brain are associated with a variety of cognitive impairments. The present results indicate that aluminum can alter the function of GABAA receptors and may suggest that aluminum can contribute to cognitive impairment through disruption of inhibitory circuits.

Smoking and Parkinson's disease. An age-dependent risk effect? The EUROPARKINSON Study Group

We studied the association between smoking and Parkinson's disease (PD) through a case-control study. Several studies have shown an inverse association between smoking and PD. This association has been interpreted as spurious by some investigators, and as real and causal by others. Several other studies did not confirm the inverse association. We included 193 prevalent cases of PD ascertained in five European prevalence surveys that followed a two-phase design of screening and clinical examination. Each case was matched by center, age (+/- 2 years), and gender to three control subjects drawn from the same populations (N = 579). Information on smoking was obtained through direct or proxy interview. Overall, there was no association between ever smoking and PD (odds ratio = 1.1; p = 0.6). Analyses stratified by age showed that ever smoking was associated with a decreased risk of PD in the younger individuals (odds ratio = 0.4; p = 0.03) and with a significant trend of increasing risk with advancing age (p = 0.003). The risk of PD in relation to smoking is strongly modified by age; smoking may be protective in the younger cases but not in the older cases. This finding may explain the conflicting results from previous studies.

Gastrointestinal absorption of aluminum is increased in Down's syndrome

Individuals with Down's Syndrome (DS) develop the neuropathological features of senile dementia of the Alzheimer's type (SDAT) by early middle age. Because of recent evidence that gastrointestinal (GI) aluminum (Al) absorption is increased in patients with SDAT, and that Al may contribute to associated neuropathological changes, we have investigated the GI uptake of Al in patients with DS by two methods. The first measured the absorption of 27Al at concentrations associated with antacid use, in the presence of citrate, using atomic absorption spectrometry. There was no difference between basal blood concentrations of 27Al in 15 DS subjects (36-46 years) and 15 age-matched controls. The mean increase in 27Al blood concentrations 60 minutes after the dose of Al was four times greater in the DS group than in controls (p < 0.001). The second measured GI absorption of 26Al under normal dietary conditions using accelerator mass spectrometry. With 26Al the mean Al absorption in DS subjects (n = 5) exceeded that of controls (n = 4) by a factor of 6 (p < 0.02). Although the mechanisms of enhanced absorption are unknown, the data indicate that similar abnormalities in the GI handling of Al occur in both SDAT and DS suggesting that it may be advisable to minimize dietary exposure to Al in subjects at risk of developing Alzheimer-type pathology.

A case-control study of Alzheimer's disease and aluminium occupation

BACKGROUND

We examined clinically diagnosed Alzheimer's disease patients and controls, and collected information from informants, to examine the association between Alzheimer's disease and aluminium occupation.

METHOD

An unmatched case-control study comparing 198 cases of Alzheimer's disease (ADRDA-NINCDS diagnostic criteria), to selected controls (164 other dementias and 176 nondementing group) in respect of their occupational history. The subjects included all patients referred to and seen by the first author during a 2 year study period.

RESULTS

Twenty-two of 198 patients with Alzheimer's disease (11.1%) reported having an aluminium occupation at some stage in their working life compared with 39 of 340 controls (11.5%), odds ratio 0.98, 95% Cl 0.53-1.75, P > 0.05. Aluminium workers reported to have worked in direct contact with aluminium dust and fumes did not appear to be at any greater risk than other workers who were employed at the same factory, odds ratio 1.19, 95% Cl, 0.64-4.18, P > 0.05.

CONCLUSION

There is no evidence to support an association between having previously worked in an aluminium factory and the risk of Alzheimer's disease later in life.

Fatal encephalopathy after otoneurosurgery procedure with an aluminum-containing biomaterial

Refractory status epilepticus was observed in two patients who underwent vestibular neurectomy. We investigated the relationship with the use of an aluminum containing bone cement during the procedure. Two patients developed focal and thereafter generalized seizures in the late postoperative period of vestibular neurectomy (respectively after 42 and 35 days). A cement (1 g aluminum-calcium fluorosilicate) was used during the procedure to bridge bone defects. Both patients presented cerebrospinal fluid fistula. Investigations excluded common etiologies, in particular infections, and a toxic origin was suspected. Aluminum concentration was determined repeatedly in serum urine, cerebrospinal fluid and retroauricular fistula. The highest aluminum values were respectively in case 1 and 2, 112 and 63 micrograms/L for the cerebrospinal fluid, 495 and 1440 micrograms/L for the fistula, 4.4 and 4.4 micrograms/L in serum. Desferrioxamine was used as chelating agent and aluminum elimination was analyzed in the urine. Status epilepticus became refractory to intensive care therapy. The patients never recovered normal consciousness. Case 1 died 143 days after the procedure and case 2 at 80 days from brain failure. Brain post-mortem examination was obtained in Case 2. Brain aluminum concentration was 2.5 micrograms/g (wet weight) (0.85 micrograms/g in a control non exposed cadaver). The cement (0.2 g) was incubated in vitro (16 h-37 degrees C) with the cerebrospinal fluid of a control patient (cerebrospinal fluid aluminum 8 micrograms/L): aluminum concentration reached 2750 micrograms/L. A close contact between an aluminum containing cement and the cerebrospinal fluid may have resulted in encephalopathy and fatal status epilepticus in these two patients.

Aluminum toxicity in rat hippocampal neurons

A brief exposure of dissociated hippocampal culture to aluminum (AlCl3, 60 min) is toxic to neurons. The aluminum toxicity is independent of calcium or glutamate receptor activation. However, at a high concentration (1 mM), aluminum seems to have a protective effect.