Aluminum exposure in chronic renal failure in iberoamerica at the end of the 1990s: overview and perspectives

A single-oral bolus of 100,000 IU of cholecalciferol at hospital admission did not improve outcomes in the COVID-19 disease: the COVID-VIT-D-a randomised multicentre international clinical trial

BACKGROUND

Vitamin D status has been implicated in COVID-19 disease. The objective of the COVID-VIT-D trial was to investigate if an oral bolus of cholecalciferol (100,000 IU) administered at hospital admission influences the outcomes of moderate-severe COVID-19 disease. In the same cohort, the association between baseline serum calcidiol levels with the same outcomes was also analysed.

METHODS

The COVID-VIT-D is a multicentre, international, randomised, open label, clinical trial conducted throughout 1 year. Patients older than 18 years with moderate-severe COVID-19 disease requiring hospitalisation were included. At admission, patients were randomised 1:1 to receive a single oral bolus of cholecalciferol (n=274) or nothing (n=269). Patients were followed from admission to discharge or death. Length of hospitalisation, admission to intensive care unit (ICU) and mortality were assessed.

RESULTS

In the randomised trial, comorbidities, biomarkers, symptoms and drugs used did not differ between groups. Median serum calcidiol in the cholecalciferol and control groups were 17.0 vs. 16.1 ng/mL at admission and 29.0 vs. 16.4 ng/mL at discharge, respectively. The median length of hospitalisation (10.0 [95%CI 9.0-10.5] vs. 9.5 [95%CI 9.0-10.5] days), admission to ICU (17.2% [95%CI 13.0-22.3] vs. 16.4% [95%CI 12.3-21.4]) and death rate (8.0% [95%CI 5.2-12.1] vs. 5.6% [95%CI 3.3-9.2]) did not differ between the cholecalciferol and control group. In the cohort analyses, the highest serum calcidiol category at admission (>25ng/mL) was associated with lower percentage of pulmonary involvement and better outcomes.

CONCLUSIONS

The randomised clinical trial showed the administration of an oral bolus of 100,000 IU of cholecalciferol at hospital admission did not improve the outcomes of the COVID-19 disease. A cohort analysis showed that serum calcidiol at hospital admission was associated with outcomes.

TRIAL REGISTRATION

COVID-VIT-D trial was authorised by the Spanish Agency for Medicines and Health products (AEMPS) and registered in European Union Drug Regulating Authorities Clinical Trials (EudraCT 2020-002274-28) and in ClinicalTrials.gov ( NCT04552951 ).

Serum Markers of Low-Turnover Bone Disease in Mexican Children with Chronic Kidney Disease Undergoing Dialysis

Background

The frequency of low-turnover bone disease (LTBD) in patients with chronic kidney disease (CKD) has increased in past years. This change is important because LTBD is associated with bone pain, growth delay, and higher risk for bone fractures and extraosseous calcifications. LTBD is a histological diagnosis. However, serum markers such as parathyroid hormone (PTH) and calcium levels offer a noninvasive alternative for diagnosing these patients.

Objective

To describe the prevalence of LTBD in pediatric patients with renal failure undergoing some form of renal replacement therapy, using serum calcium and intact PTH levels as serum markers.

Methods

In this cross-sectional study, 41 children with CKD undergoing dialysis treatment (31 on continuous ambulatory peritoneal dialysis and 10 on hemodialysis) were included. There were no inclusion restrictions with respect to gender, cause of CKD, or dialysis modality. The children were studied as outpatients. The demographic data, CKD course, time on dialysis, phosphate-binding agents, and calcitriol prescription were registered, as well as weight, height, Z-score for height, linear growth rate, and Z-score for body mass index. Serum calcium, phosphorus, aluminum, PTH, alkaline phosphatase, osteocalcin, glucose, creatinine, urea, cholesterol, and triglycerides were measured.

Results

There were 20 (48.8%) children with both PTH <150 pg/mL and corrected total calcium >10 mg/dL who were classified as having LTBD[(+)]; the remaining 21 (51.2%) children were classified as having no LTBD[(–)]. The LTBD(+) patients were younger (11.2 ± 2.7 vs 13.2 ± 2.4 years, p < 0.01) but they had no differences regarding Z-scores for height. Linear growth in 6 months was less than expected in both groups (-0.15 ± 0.23 cm/month), but the difference between expected and observed growth was higher in the LTBD(+) group (-0.24 ± 0.14 vs –0.07 ± 0.28 cm/mo, p < 0.03). LTBD(+) patients also had lower serum creatinine (8.69± 2.75 vs 11.19 ± 3.17 mg/dL, p < 0.01), higher serum aluminum levels [median (range) 38.4 (9 – 106) vs 28.1 (9 – 62) μg/L, p < 0.05], and lower systolic blood pressure (112.0 ± 10.3 vs 125.0 ±12.9 mmHg, p < 0.015) and diastolic blood pressure (76.0 ± 9.7 vs 84.5 ± 8.2 mmHg, p < 0.017). A significant correlation was found between PTH and alkaline phosphatase ( r = 0.68, p < 0.001), but not between PTH and aluminum.

Conclusion

The LTBD(+) biochemical profile was found in 48.8% of the children and was associated with impaired linear growth. Aluminum contamination, evidenced by higher serum aluminum levels, may have had a pathogenic role in these disorders. Higher systolic and diastolic blood pressure levels may be related to higher serum PTH levels.

Effects of Aluminum Exposure on the Bone Stimulatory Growth Factors in Rats

Aluminum (Al) is considered to be a potentially toxic metal and inhibits bone formation. Transforming growth factor β1 (TGF-β1) and bone morphogenetic protein 2 (BMP-2) play an important role in regulating the bone formation. Therefore, this study aimed to investigate the effects of Al on the TGF-β1 and BMP-2 in rats. In this study, Wistar rats were randomly divided into Al-treated group and control group. The Al-treated rats were provided with drinking water containing 100 mg/L AlCl3, and the control rats were given distilled water for 30, 60, and 90 days, respectively. Ten rats were sacrificed in each group every 30 days. The Al-treated rats showed lower body weight and higher serum and bone levels of Al compared with the control rats. The expression levels of TGF-β1 and BMP-2 were also significantly decreased in the Al-treated rats. Serum levels of bone gamma-carboxyglutamic acid protein (BGP), carboxy-terminal propeptide of type I procollagen (PICP), and bone alkaline phosphatase (B-ALP) were markedly lower in the Al-treated groups than in the control group. These results indicate that Al inhibits the expression of TGF-β1 and BMP-2 in bone, which inhibits the activity of osteoblasts and reduces the synthesis of BGP, B-ALP, and type I collagen, thereby inhibiting bone formation.

Possible peripheral markers for chronic aluminium toxicity in Wistar rats

This investigation gives detailed analysis of peripheral marker enzymes as well as neurobehavioral tests following chronic aluminium (Al) exposure (10 mg/kg b.w. for 12 weeks intragastrically). We observed a significant decrease in the levels of serum cholinesterase after toxicity. The enzymatic activity of cytochrome oxidase (CO), the terminal enzyme of the electron transport chain, was significantly diminished and that of glucose-6-phosphate dehydrogenase (G-6-PD) was significantly enhanced. Neuromuscular co-ordination was assessed using motor and memory function tests. Deficits were observed suggesting a probable model for chronic Al neurotoxicity.

Synthesis of Imine-Naphthol Tripodal Ligand and Study of Its Coordination Behaviour towards Fe(III), Al(III), and Cr(III) Metal Ions

A hexadentate Schiff base tripodal ligand is synthesized by the condensation of tris (2-aminoethyl) amine with 2-hydroxy-1-naphthaldehyde and characterized by various spectroscopic techniques like UV-VIS, IR, NMR, MASS, and elemental analysis. The solution studies by potentiometric and spectrophotometric methods are done at 25 ± 1°C, µ = 0.1 M KCl, to calculate the protonation constants of the ligand and formation constants of metal complexes formed by the ligand with Fe(III), Al(III), and Cr(III) metal ions. The affinity of the ligand towards Fe(III) is compared with deferiprone (a drug applied for iron intoxication) and transferrin (the main Fe(III) binding protein in plasma). Structural analysis of the ligand and the metal complexes was done using semiempirical PM6 method. Electronic and IR spectra are calculated by semiempirical methods and compared with experimental one.

On-line solid-phase extraction and multisyringe flow injection analysis of Al(III) and Fe(III) in drinking water

A new analytical method was developed for on-line monitoring of residual coagulants (aluminium and iron salts) in potable water. The determination was based on a sequential procedure coupling an extraction/enrichment step of the analytes onto a modified resin and a spectrophotometric measurement of a surfactant-sensitized binary complex formed between eluted analytes and Chrome Azurol S. The optimization of the solid phase extraction was performed using factorial design and a Doehlert matrix considering six variables: sample percolation rate, sample metal concentration, flow-through sample volume (all three directly linked to the extraction step), elution flow rate, concentration and volume of eluent (all three directly linked to the elution step). A specific reagent was elaborated for sensitive and specific spectrophotometric determination of Al(III) and Fe(III), by optimizing surfactant and ligand concentrations and buffer composition. The whole procedure was automated by a multisyringe flow injection analysis (MSFIA) system. Detection limits of 4.9 and 5.6 microg L(-1) were obtained for Al(III) and Fe(III) determination , respectively, and the linear calibration graph up to 300 microg L(-1) (both for Al(III) and Fe(III)) was well adapted to the monitoring of drinking water quality. The system was successfully applied to the on-site determination of Al(III) and Fe(III) at the outlet of two water treatment units during two periods of the year (winter and summer conditions).

Comparative effects of aluminum and ouabain on synaptosomal choline uptake, acetylcholine release and (Na+/K+)ATPase

Closing the gap between adverse health effects of aluminum and its mechanisms of action still represents a huge challenge. Cholinergic dysfunction has been implicated in neuronal injury induced by aluminum. Previously reported data also indicate that in vivo and in vitro exposure to aluminum inhibits the mammalian (Na(+)/K(+))ATPase, an ubiquitous plasma membrane pump. This study was undertaken with the specific aim of determining whether in vitro exposure to AlCl(3) and ouabain, the foremost utilized selective inhibitor of (Na(+)/K(+))ATPase, induce similar functional modifications of cholinergic presynaptic nerve terminals, by comparing their effects on choline uptake, acetylcholine release and (Na(+)/K(+))ATPase activity, on subcellular fractions enriched in synaptic nerve endings isolated from rat brain, cuttlefish optic lobe and torpedo electric organ. Results obtained show that choline uptake by rat synaptosomes was inhibited by submillimolar AlCl(3), whereas the amount of choline taken up by synaptosomes isolated from cuttlefish and torpedo remained unchanged. Conversely, choline uptake was reduced by ouabain to a large extent in all synaptosomal preparations analyzed. In contrast to ouabain, which modified the K(+) depolarization evoked release of acetylcholine by rat, cuttlefish and torpedo synaptosomal fractions, AlCl(3) induced reduction of stimulated acetylcholine release was only observed when rat synaptosomes were challenged. Finally, it was observed that the aluminum effect on cuttlefish and torpedo synaptosomal (Na(+)/K(+))ATPase activity was slight when compared to its inhibitory action on mammalian (Na(+)/K(+))ATPase. In conclusion, inhibition of (Na(+)/K(+))ATPase by AlCl(3) and ouabain jeopardized the high-affinity (Na(+)-dependent, hemicholinium-3 sensitive) uptake of choline and the Ca(2+)-dependent, K(+) depolarization evoked release of acetylcholine by rat, cuttlefish and torpedo synaptosomal fractions. The effects of submillimolar AlCl(3) on choline uptake and acetylcholine release only resembled those of ouabain when rat synaptosomes were assayed. Therefore, important differences were found between the species regarding the cholinotoxic action of aluminum. The variability of (Na(+)/K(+))ATPase sensitivity to aluminum of cholinergic neurons might contribute to their differential susceptibility to this neurotoxic agent.

The Importance of Water Quality and Haemodialysis Fluid Composition

Treatment of renal failure by haemodialysis uses dialysis fluid to facilitate the normalization of electrolyte and acid base abnormalities and the removal of low molecular weight uraemic compounds present in the plasma such as urea. The dialysis fluid is a continuously produced blend of treated tap water and a concentrated solution containing electrolytes, buffer, and glucose. The water used originates as drinking water but undergoes additional treatment. Recent surveys have indicated that the chemical and microbiological content of such water frequently fails to meet the requirements of established standards, and its bacterial content arising from the presence of a biofilm in the water distribution network or the hydraulic circuit of the dialysis machine is a contributory factor to the chronic inflammatory state in patients undergoing regular dialysis. The composition of the dialysis fluid plays an important role in the modulation of complications associated with end-stage renal disease, as well as those associated with the treatment itself. The avoidance of complications arising from water contaminants requires a constant and vigorous attention to water quality, whilst with the composition of electrolytes and buffer there is a trend towards greater individualization to provide a high degree of treatment tolerance.

Prosecution after an outbreak of subacute aluminum intoxication in a hemodialysis center

Criminal prosecution of physicians for the death of patients has been extraordinarily rare, but there seems to be a rising trend. This case report describes the medical and judicial implications of criminal prosecution of two doctors at a hemodialysis clinic in the Netherlands Antilles that had to stand trial over the death of 10 dialysis patients. The patients died of subacute aluminum intoxication when aluminum leached from the cement lining of a newly installed water distribution pipe into the water supply of the dialysis center that did not make use of a water treatment system (WTS). Data of the case history of the dialysis patients, the criminal prosecution, preliminary judicial inquiry, the defense arguments and verdicts are reviewed. The prosecutor first decided to dismiss the case, but after an appeal by the families, the Court of Appeal decided to pursue prosecution for gross negligence. It held that the dialysis center should have used a WTS and also held that the dialysis staff reacted insufficiently on extra alarms on the dialysis machines in the two days after the new water distribution pipe was put in use. From June 6, 1998 until January 1999 a preliminary judicial inquiry was performed in The Netherlands and on Curaçao. After a cross-examination of 13 court-appointed experts by the prosecutor and the investigative judge, the prosecutor charged the two physicians of gross negligence manslaughter for not testing the composition of the water after the construction at the water distribution network. A prison sentence with probation of 6 months was demanded. The District Court disagreed on all issues with the prosecutor, but nevertheless held the medical director of Diatel guilty for performing hemodialysis without a WTS. In May 2000, the Court of Appeal held that it was not allowed to rule on the omission to install a WTS because this issue was not included in the charge and overturned the conviction. Medical personnel in charge of potentially dangerous procedures should be prepared for unexpected changes in the quality of their treatment. Because court-appointed experts might have an extraordinary role in the decision making process, guidelines should be prepared to ensure the trustworthiness of their testimony.

Investigation of the aluminium biokinetics in humans: a 26Al tracer study

Despite the well-known toxicity of aluminium in chronic renal failure, a solid database on its biokinetics has been difficult to establish. A highly sensitive method using (26)Al as tracer and accelerator mass spectrometry (AMS) for detection was used. No perturbing background and saturation effects were taken into account using a delta function input of aluminium in time. Aluminium absorption, distribution, speciation and excretion in six healthy volunteers and in two patients with chronic renal failure were investigated following administration of a single oral or i.v. dose of (26)Al. Serial samples of blood and urine were taken. In a speciation study, the time dependence of the binding of (26)Al to low-molecular weight molecules in serum was investigated. The measured data were compared and interpreted with simulations in an open compartmental model. Fractional absorption, distribution, excretion and time constants for the aluminium transport were determined. Typical intestinal absorption rates for AlCl(3) were found to be in the range of 10(-3). The ultrafiltrable percentage of aluminium in serum of one volunteer was estimated to be 5.6+/-0.8%. Differences between healthy volunteers and patients with chronic renal failure were deduced. The employed method using (26)Al and ams has proven to be highly sensitive for investigations of aluminium biokinetics at the ultra-trace element level. With the model, the measured values of (26)Al in serum and urine were used to precisely determine absorption, speciation, distribution, retention and excretion of aluminium in humans.

RENAL RESEARCH INSTITUTE SYMPOSIUM: The Implications of Water Quality in Hemodialysis

Water used in dialysis requires additional treatment to minimize patient exposure to potential contaminants that may be present in drinking water. Although standards for the chemical purity of water are in existence and have eliminated many of the problems seen in renal units in the 1970s, some problems remain, and the importance of newer contaminants arising from changes in water treatment at the municipal level are being recognized. Despite this, recent surveys have indicated considerable shortcomings in compliance with chemical standards. The water quality used in the preparation of dialysis fluid also requires minimal bacterial content. Staff working in renal units are frequently unaware of the level of microbiologic contamination in their dialysis fluid arising from the presence of biofilm in the dialysis machines and the water distribution network. Bacterial fragments generated by such biofilms are able to cross the dialysis membrane and stimulate an inflammatory response in the patient. Such inflammation has been implicated in the mortality and morbidity associated with dialysis. The desire to improve treatment outcomes has led to the application of more stringent standards for the microbiologic purity of dialysis fluid and to the introduction of ultraclean dialysis fluid into clinical practice.

Aluminum: impacts and disease

Aluminum is the most widely distributed metal in the environment and is extensively used in modern daily life. Aluminum enters into the body from the environment and from diet and medication. However, there is no known physiological role for aluminum within the body and hence this metal may produce adverse physiological effects. The impact of aluminum on neural tissues is well reported but studies on extraneural tissues are not well summarized. In this review, the impacts of aluminum on humans and its impact on major physiological systems are summarized and discussed. The neuropathologies associated with high brain aluminum levels, including structural, biochemical, and neurobehavioral changes, have been summarized. In addition, the impact of aluminum on the musculoskeletal system, respiratory system, cardiovascular system, hepatobiliary system, endocrine system, urinary system, and reproductive system are discussed.

The effect of an iron supplement on serum aluminum level and desferrioxamine mobilization test in hemodialysis patients

BACKGROUND

The serum aluminum (Al) measurement with desferrioxamine (DFO) mobilization is a screening test for uremic patients with an Al overload. In these patients, body iron status is one of the factors affecting the serum Al level. This study is designed to elucidate the effects of iron supplements on the serum Al and the DFO mobilization test.

METHODS

Our study featured ten hemodialysis patients with iron deficiency anemia. The iron supplement was given intravenously with saccharated ferric oxide, 40 mg three times weekly, at the end of each hemodialysis. The total amount of iron supplement was 1,000 mg. All the patients underwent a DFO test at a dose of 5 mg/kg. The same test was repeated two weeks after completion of the iron supplement.

RESULTS

After the iron supplement, patients' iron deficiency anemia improved with a serum ferritin elevation from 312.4 +/- 589.5 to 748.2 +/- 566.2 microg/L (p < 0.01), and iron saturation from 21.6 +/- 20.3 to 41.1 +/- 21.7% (p = 0.06). The basal serum Al level decreased from 34.3 +/- 13.8 to 21.8 +/- 8.5 microg/L (p = 0.01). In the DFO mobilization test, the peak serum Al level decreased from 63.4 +/- 19.3 to 50.7 +/- 20.5 microg/L (p < 0.01). The amount of Al increment (deltaAl) in DFO test was not changed (29.1 +/- 12.0 vs. 28.9 +/- 15.9 microg/L, p = 0.86). The change in basal Al level tended to negatively correlate with the percentage of increment in iron saturation (r = -0.628, p = 0.05).

CONCLUSION

Results in this study suggest that iron supplements may significantly reduce the basal serum Al and peak Al in DFO mobilization test, without significant change of the mean deltaAl. The data presented indicate that in the interpretation of serum aluminum levels the iron status should be taken into account.