Dialysis encephalopathy in a non-dialysed uraemic boy treated with aluminium hydroxide orally

Glutathione, Cysteine, and D-Penicillamine Role in Exchange of Silver Metal from the Albumin Metal Complex

The purpose of this study is to investigate the exchange reaction taking place among the bovine serum albumin (BSA), 5,5'-dithiobis-(2-nitrobenzoic acid (ESSE), reduced glutathione, N-acetylcysteine, D-penicillamine (thiolates), and silver metal (AgI). For this purpose, stock solutions of BSA and Ellman's reagent were prepared by dissolving 264 mg of BSA in 5 ml of reaction buffer (0.1 M KH2PO4 at pH 7.8) and 23.8 mg of ESSE in 1.0 ml of reaction buffer which were mixed together. Mixture of BSA-AgI was prepared in a separate procedure by dissolving 0.17 mg of silver nitrate in 1 ml of reaction buffer and then dissolving BSA (200 mg) in the same solution of silver nitrate. Blocking of Cys-34 of BSA with AgI was confirmed by treating different dilutions of BSA-AgI (500 μM) solutions with the solutions of ESSE (85 μM) and ES- (85 μM) and recording the spectra (300-450) with a UV-visible spectrophotometer. The chromatographed AgI-modified BSA ((BSA-S)AgI)) samples (typically 500 μM) were subsequently mixed with thiolates (reduced glutathione, N-acetylcysteine, and D-penicillamine). AgI and modified BSA (typically 500 μM each) were treated with these low molecular weight thiolates and allowed to react overnight followed by chromatographic separation (Sephadex G25). The redox reactions of AgI-modified BSA with various low molecular weight thiols revealed a mechanically important phenomenon. In the case of reduced glutathione and N-acetylcysteine, we observed the rapid release of a commensurate amount of Ellman's anion, indicating that an exchange has taken place and low molecular weight thiols (RSH) substituted AgI species at the Cys-34 of BSA eventually forming disulfide (BSA-SSR) at Cys-34. It can be anticipated from the phase of study involving bovine serum albumin that low molecular weight thiolates (reduced glutathione and N-acetylcysteine) take off AgI which are attached to proteins elsewhere in the physiological system, making these toxic metals free for toxic action.

Calcium Carbonate as a Phosphate Binder: Is There a Need to Adjust Peritoneal Dialysate Calcium Concentrations for Patients Using CaCO3?

The widespread use of calcium carbonate as a phosphate binder is limited by its tendency to develop hypercalcemia in some patients using effective dosages needed to control hyperphosphatemia. Most common continuous ambulatory peritoneal dialysis (CAPD) regimens using dialysis solutions containing 3.5 mEqlL of calcium result in net absorption of calcium from the dialysis solution and, hence limit the amount of oral calcium that can be administered. Peritoneal dialysis solutions with reduced calcium levels are needed for effective use of CaCO3 to control hyperphosphatemia in some dialysis patients.

Risk Factors for Hyperaluminemia in Continuous Ambulatory Peritoneal Dialysis

The authors evaluated risk factors for hyperaluminemia and aluminum toxicity in 51 CAPD patients, who received aluminum-containing phosphate binders. Serum aluminum correlated with total intake of elemental aluminum after starting CAPD (p = 0.001), with aluminum intake in the previous six months (p = 0.001), with duration of CAPD (p = 0.003), and with serum phosphate (p = 0.05). Eight patients had elevated serum aluminum, but only one had clincial evidence of aluminum toxicity (he had been on hemodialysis with untreated water until he was changed to CAPD 30 months before the study). Although the incidence of clinical aluminum toxicity appears to be low, we conclude that the aluminum intake from aluminum-containing phosphate binders is a major factor in the evolution of hyperaluminemia and, potentially, aluminum toxicity in CAPD patients. We believe that alternative effective, phosphate binders are much needed.

It has been shown that tissue accumulation of aluminum in brain, bone and blood in uremic patients causes encephalopathy (I. 2), osteomalacia (3, 4), and anemia (5, 6). Clinically aluminum toxicity has been observed mainly in hemodialysis patients (1–6), although it has been reported in few cases before dialysis (7–9) and in those on continuous ambulatory peritoneal dialysis (10. II). The major cause of aluminum toxicity during hemodialysis has been transfer of aluminum from untreated water in the dialysate (1–5); this mechanism has tended to obscure the contribution of other factors, such as diet and drugs. Peritoneal dialysate contains a low concentration of aluminum (less than 15 μg/L) and there is a net removal of aluminum in the dialysate in those with serum aluminum levels within the reference range for dialysed uremics (11–13). Serial aluminum levels in CAPD patients not receiving aluminum -containing phosphate binders (ACPB) showed no significant change during a two-year follow-up (12, 14); this suggests that aluminum removal in the dialysate compensates for the failure of the kidney to excrete absorbed dietary aluminum in end-stage renal disease. Since the combination of CAPD and diet appears to have minimal influence on serum aluminum, this study was done to identify those factors which determine serum aluminum levels in CAPD patients, receiving aluminum-containing phosphate binders.

Selective Interactions of Al(III) with Plasmonic AgNPs by Colorimetric, Kinetic, and Thermodynamic Studies

In this paper, we report a simple, novel, and highly selective plasmonic nanoparticles (NPs)-based colorimetric nanoprobe for the detection of Al(III) ions in aqueous solution. 5-Hydroxy indole-2-carboxylic acid (5H-I2CA) was utilized as a reducing as well as capping agent for the preparation of silver nanoparticles (5H-I2CA@AgNPs). The interaction between Al(III) and AgNPs was determined by UV-vis absorption spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, and dynamic light scattering techniques. The absorption values (A 452-410) of the 5H-I2CA@AgNPs solution exhibited a linear correlation with Al(III) ion concentrations within the linear range of 0.1-50 nM. An outstanding selectivity toward Al(III) was demonstrated by the proposed nanoprobe in the presence of interfering cations. Kinetics was used to study the selectivity of nanoprobe, which indicated second-order kinetics, and the rate constant was very high. The activation energies of Al(III) were found to be the lowest compared to those of other interfering ions. The results of kinetics and thermodynamic study of Al(III) were compared to those of four other competing ions. The thermodynamic data reveal that the interaction best suited for Al(III) ion compared to other metal ions (Al(III) > Co(II) > Hg(II) > Cr(III) ≅ Cr(VI)). The lower detection limit of the proposed nanoprobe for Al(III) is 1 nM. The present method also holds practical applicability for real water samples.

Analysis of aluminum, minerals and trace elements in the milk samples from lactating mothers in Hamadan, Iran

The present cross-sectional study is aimed at analyzing the breast milk of lactating mothers in Hamadan, Iran for aluminum and several minerals and trace elements. Ten governmental health care centers were utilized to facilitate collection of breast milk samples. The breast milk samples were collected at 1, 2, 6, 7, and 12 months postpartum from one hundred healthy lactating women, who delivered full-term newborns. Detection of sodium (Na), zinc (Zn), calcium (Ca), iron (Fe), copper (Cu), magnesium (Mg) and aluminum (Al) levels was conducted with the use of Inductively Coupled Plasma Mass Spectrometry (ICP-MS). This method has shown high accuracy, precision, sensitivity, and linearity for the wide range of concentrations. The accumulated data were not normally distributed; thus, the non-parametric Mann-Whitney U test was used in the statistical analysis of the results. Mean concentrations of Fe, Zn, Cu, Ca, Mg, and Na were 0.75, 1.38, 0.35, 255, 34.58, and 155.72 μg/mL, respectively. The mean level of Al, a well-known neurotoxic metal, was determined to be an alarming 0.191 μg/mL. Moreover, 95% of participants contained very harmful concentrations of Al in their milk. This study also revealed Zn deficiency in about 50% of milk samples. Further investigation is needed to elucidate sources of exposure and factors that may influence maternal and fetal exposure to aluminum.

Mentha-Stabilized Silver Nanoparticles for High-Performance Colorimetric Detection of Al(III) in Aqueous Systems

The present paper reports a facile and selective colorimetric method for the detection of potential environmental and health hazardous metal ions using green synthesized silver nanoparticles (AgNPs). Here the organic functional groups present in the plant extract (Mentha arvensis) are used as reductants and stabilizers in the synthesis of AgNPs. They also provide a suitable binding site to the (Al(III)) analyte in the detection mechanism. The leaf extract of Mentha arvensis was used to synthesize AgNPs at room-temperature and at 80 °C. The AgNPs synthesized at 80 °C exhibit excellent selective colorimetric detection of Al(III). The as-synthesized AgNPs have been characterized, and the synthesis, stabilization of NPs and detection mechanism has also been illustrated by using UV-vis, XPS, FTIR, TEM, EDX, SEM, AAS, and TGA analytical tools and techniques. The selectivity of detection probe was supported by the reaction between probe and metal ions followed first-order kinetics having the highest value of the regression coefficient (R² = 0.99) for Al(III) and the analysis of thermodynamic parameters. The prepared sensor showed a lower limit of detection (LOD) of 1 nM (S/N = 3.2) in real water samples. The proposed method can be successfully utilized for the detection of Al(III) from both drinking and real water samples at the nanomolar level.

Aluminum as a toxicant

Although aluminum is the most abundant metal in nature, it has no known biological function. However, it is known that there is a causal role for aluminum in dialysis encephalopathy, microcytic anemia, and osteomalacia. Aluminum has also been proposed to play a role in the pathogenesis of Alzheimer’s disease (AD) even though this issue is controversial. The exact mechanism of aluminum toxicity is not known but accumulating evidence suggests that the metal can potentiate oxidative and inflammatory events, eventually leading to tissue damage. This review encompasses the general toxicology of aluminum with emphasis on the potential mechanisms by which it may accelerate the progression of chronic age-related neurodegenerative disorders.

Colorimetric detection of Al(iii) in vermicelli samples based on ionic liquid group coated gold nanoparticles

We synthesized ionic liquid group coated gold nanoparticles and used them in determining the concentrations of aluminum in vermicelli samples.

Does neurotransmission impairment accompany aluminium neurotoxicity?

Neurobehavioral disorders, except their most overt form, tend to lie beyond the reach of clinicians. Presently, the use of molecular data in the decision-making processes is limited. However, as details of the mechanisms of neurotoxic action of aluminium become clearer, a more complete picture of possible molecular targets of aluminium can be anticipated, which promises better prediction of the neurotoxicological potential of aluminium exposure. In practical terms, a critical analysis of current data on the effects of aluminium on neurotransmission can be of great benefit due to the rapidly expanding knowledge of the neurotoxicological potential of aluminium. This review concludes that impairment of neurotransmission is a strong predictor of outcome in neurobehavioral disorders. Key questions and challenges for future research into aluminium neurotoxicity are also identified.

Potential Ototoxicity of Aluminum in Hemodialysis Patients

OBJECTIVES/HYPOTHESIS

Aluminum (Al) is a neurotoxin in both human and animal models. Al accumulation is usually observed in patients with end-stage renal disease (ESRD). To clarify whether Al also exhibits toxic effects on the specified neural organ of inner ear, we recruited hemodialysis (HD) patients to investigate the effect of serum Al level on the auditory physiology.

STUDY DESIGN

Forty patients in maintenance HD as well as 40 age-matched healthy subjects without hearing complaints were enrolled. The auditory function tests, including pure-tone audiometry (PTA), distortion-product otoacoustic emissions (DPOAEs), and auditory brainstem response (ABR) were performed in all subjects. The serum Al levels determined within 3 months of auditory tests were used for analysis.

RESULTS

High-frequency hearing impairment was the predominant auditory dysfunction in HD patients who showed worse high-tone hearing level on PTA and diminished amplitudes of DPOAEs at 3 K and 4 K as compared with the controls (P < .001). Age was a significant factor determining the auditory dysfunction in both HD patients and control subjects. After age correction, serum Al level correlated reversely with the amplitude of DPOAEs-2 K (P = .002), but not with amplitudes of DPOAEs-3 K, -4 K, hearing levels on PTA, or wave latencies on ABR.

CONCLUSION

High-frequency hearing impairment is a common presentation in HD patients. Serum Al level correlates reversely with the amplitude of DPOAEs-2 K but not those of DPOAEs-3 K, -4 K, hearing levels on PTA, and wave latencies on ABR. Possibly, the correlation between the Al level and the high-frequency OAE results was obscured by the significantly diminished amplitudes of DPOAEs-3 K, -4 K in ESRD patients. These results implicate that the effect of Al is mainly of cochlear origin rather than of retrocochlear origin.

Aluminum neurotoxicity in preterm infants receiving intravenous-feeding solutions

BACKGROUND

Aluminum, a contaminant of commercial intravenous-feeding solutions, is potentially neurotoxic. We investigated the effect of perinatal exposure to intravenous aluminum on the neurologic development of infants born prematurely.

METHODS

We randomly assigned 227 premature infants with gestational ages of less than 34 weeks and birth weights of less than 1850 g who required intravenous feeding before they could begin enteral feeding to receive either standard or specially constituted, aluminum-depleted intravenous-feeding solutions. The neurologic development of the 182 surviving infants who could be tested was assessed by using the Bayley Scales of Infant Development at 18 months of age.

RESULTS

The 90 infants who received the standard feeding solutions had a mean (+/-SD) Bayley Mental Development Index of 95+/-22, as compared with 98+/-20 for the 92 infants who received the aluminum-depleted solutions (P=0.39). In a planned subgroup analysis of infants in whom the duration of intravenous feeding exceeded the median and who did not have neuromotor impairment, the mean values for the Bayley Mental Development Index for the 39 infants who received the standard solutions and the 41 infants who received the aluminum-depleted solutions were 92+/-20 and 102+/-17, respectively (P=0.02). The former were significantly more likely (39 percent, vs. 17 percent of the latter group; P=0.03) to have a Mental Development Index of less than 85, increasing their risk of subsequent educational problems. For all 157 infants without neuromotor impairment, increasing aluminum exposure was associated with a reduction in the Mental Development Index (P=0.03), with an adjusted loss of one point per day of intravenous feeding for infants receiving the standard solutions.

CONCLUSIONS

In preterm infants, prolonged intravenous feeding with solutions containing aluminum is associated with impaired neurologic development.

The renal bone diseases in children treated with dialysis

Renal osteodystrophy represents a spectrum from high- to low-turnover bone lesions. The specific pattern, however, may change during selected therapeutic interventions. As in the past, osteitis fibrosa remains the most frequent histologic lesion in pediatric patients on dialysis, although recently the prevalence of low-turnover bone lesions without aluminum toxicity has been increasing in the pediatric population. This may be a consequence of aggressive calcitriol and calcium therapy. The different factors involved in the development of secondary hyperparathyroidism include hyperphosphatemia, hypocalcemia, altered vitamin D synthesis, impairments in parathyroid hormone (PTH) secretion and metabolism, and, recently, possible downregulation of renal PTH/PTH-rP messenger RNA receptor. New developments in molecular biology have demonstrated the relationship between vitamin D and PTH. The use of high-dose pulse intravenous, intraperitoneal, and oral calcitriol therapy has significantly decreased serum PTH levels and retarded the progression of osteitis fibrosa. These therapeutic interventions, however, may have led to the development of adynamic bone lesions. The impact of adynamic bone lesions in the young and growing skeleton remains to be determined.

Bone and mineral metabolism in childhood end-stage renal disease

Renal osteodystrophy represents a spectrum from high to low turn-over lesions of bone, and the specific pattern may change during the evolution of chronic renal failure and as a consequence of specific therapeutic interventions. Although secondary hyperparathyroidism remains the predominant histologic lesion in patients undergoing maintenance dialysis, recent evidence indicates higher frequency of adynamic lesion not associated with aluminum intoxication. The different factors involved in the development of each of the histologic subtypes have been described together with the clinical manifestations of renal bone disease in childhood. Avoidance of aluminum-containing medications and the intermittent administration of calcitriol are effective approaches for the management of the renal bone diseases. The long-term consequences of the adynamic lesion remain to be determined.

Effects of chronic dietary aluminum on local cerebral glucose utilization in rats

Beginning at 4 weeks of age normal, male, Sprague-Dawley rats were reared on Purina Laboratory Chow and drinking water containing 100 microM AlCl3. After 2 years, local rates of cerebral glucose utilization were determined with the autoradiographic [14C] deoxyglucose method in the brain as a whole and in 25 brain regions in 6 treated rats and 4 age-matched controls. The results indicate that any effects of chronic aluminum in the diet on rates of cerebral glucose utilization are small. In the brain as a whole, the mean rate of glucose utilization in the aluminum-treated rats was 6% lower than that of the controls (p = 0.09). In 21 of the 25 brain regions examined mean rates of glucose utilization were generally lower in the aluminum-treated rats but in none of the region were the effects statistically significant.

Improved neurological outcome in children with chronic renal disease from infancy

Progressive encephalopathy, developmental delay, microcephaly, electroencephalogram (EEG) and computed tomographic (CT) scan abnormalities have been reported in 80% of children with chronic renal failure (CRF) in infancy. Malnutrition, aluminium intoxication and psychosocial deprivation are proposed as causes. In 15 children with CRF from infancy we evaluated the effect of no aluminium salts and early vigorous nutritional and psychosocial support, in addition to the standard therapy, on neurological development. Six patients underwent dialysis (2 at birth) and 3 received transplants. None of our patients were given aluminium therapy. The nutritional status of the patients in the first 2 years of life was assessed with the waterlow classification. At the end of the follow-up period (mean 50 months range 14-148 months), patients underwent neurodevelopmental assessment, head CT scan, EEG, nerve conduction velocity (NCV) and auditory brain stem evoked response (ABER). None of our patients developed progressive encephalopathy or recurrent seizures. All have a normal neurological examination apart from hypotonia. Microcephaly was present in 5 patients. There was a good correlation between malnutrition in the first 2 years of life and microcephaly. Developmental delay was present in 3 patients; all 3 were microcephalic. There was evidence of brain atrophy on CT scan in only 3 patients. EEG was abnormal in 6 patients, but only severe in 1 patient. Only 1 patient had diminished NCV; all patients had a normal ABER. We conclude that a policy of no oral aluminium therapy and early nutritional support leads to better neurological outcome in children with CRF from infancy.

Mechanism of phosphate adsorption to a three-dimensional structure of boehmite in the presence of bovine serum albumin

A new microcrystalline boehmite (tentatively named PT-A) was synthesized as an efficient phosphate adsorbent to replace aluminum hydroxide gel. The characteristic structure of PT-A was examined by nitrogen adsorption/desorption, X-ray diffraction, deviation microscopy, and scanning electron microscopy to establish a pore structural model of PT-A. With this model structure, the details of the mechanism of interaction between PT-A and phosphate in the presence of bovine serum albumin (BSA) are discussed. PT-A is a spherical particle with a diameter of approximately 100 microns and a porous surface structure, and its inside is packed with boehmite microcrystals (crystallite size, 2 nm). PT-A has three types of pores in its structure: a micropore with a narrow size-distribution, a mesopore with a broad size-distribution, and a macropore (radii of pores are 0.7, 1-20, and approximately 300 nm, respectively). When phosphate was incubated with PT-A in human gastric and intestinal juices or in an aqueous solution containing BSA, the amounts of phosphate adsorbed by PT-A were not affected by the presence of proteins. The nitrogen adsorption/desorption isotherms and energy dispersive X-ray analyses demonstrated that phosphate could diffuse to the smaller tunnels freely even if the external surface of PT-A was covered with BSA. It was also demonstrated that the main site of adsorption for phosphate was in micropores of PT-A, whereas BSA was adsorbed only to the external surface and none entered inside smaller tunnels consisting of micro- and mesopores.

Calcium citrate without aluminum antacids does not cause aluminum retention in patients with functioning kidneys

It has been suggested that calcium citrate might enhance aluminum absorption from food, posing a threat of aluminum toxicity even in patients with normal renal function. We therefore measured serum and urinary aluminum before and following calcium citrate therapy in patients with moderate renal failure and in normal subjects maintained on constant metabolic diets with known aluminum content (967-1034 mumol/day, or 26.1-27.9 mg/day, in patients and either 834 or 1579 mumol/day, or 22.5 and 42.6 mg/day, in normal subjects). Seven patients with moderate renal failure (endogenous creatinine clearance of 43 ml/min) took 50 mmol (2 g) calcium/day as effervescent calcium citrate with meals for 17 days. Eight normal women received 25 mmol (1 g) calcium/day as tricalcium dicitrate tablets with meals for 7 days. In patients with moderate renal failure, serum and urinary aluminum were normal before treatment at 489 +/- 293 SD nmol/l (13.2 +/- 7.9 micrograms/l) and 767 +/- 497 nmol/day (20.7 +/- 13.4 micrograms/day), respectively. They remained within normal limits and did not change significantly during calcium citrate treatment (400 +/- 148 nmol/l and 600 +/- 441 nmol/day, respectively). Similarly, no significant change in serum and urinary aluminum was detected in normal women during calcium citrate administration (271 +/- 59 vs 293 +/- 85 nmol/l and 515 +/- 138 vs 615 +/- 170 nmol/day, respectively). In addition, skeletal bone aluminum content did not change significantly in 14 osteoporotic patients (endogenous creatinine clearance of 68.5 ml/min) treated for 24 months with calcium citrate, 10 mmol calcium twice/day separately from meals (29.3 +/- 13.9 ng/mg ash bone to 27.9 +/0- 10.4, P = 0.727). In them, histomorphometric examination did not show any evidence of mineralization defect. Thus, calcium citrate given alone without aluminum-containing drugs does not pose a risk of aluminum toxicity in subjects with normal or functioning kidneys, when it is administered on an empty stomach at a recommended dose of 20 mmol calcium/day.

Aluminum transfer through milk in female rats intoxicated by aluminum chloride

Female rats received an ip injection of aluminum chloride (10 mg Al/kg/d) during the first 12 d after parturition; this treatment led to a reduction in food intake associated with a reduction in body wt. Pups of the intoxicated dams showed a growth retardation after postnatal day 7. One day after treatment, the female rats intoxicated with aluminum had a considerably higher level of aluminum in milk than controls. The aluminum levels of plasma, liver, spleen, and kidneys were also significantly higher in treated female rats than controls. On the contrary, in the same tissues of pups from treated or not treated dams, no differences in aluminum levels were observed. No effect of aluminum treatment was detected on plasma silicon levels in dams and pups.

Effects of postnatal aluminum exposure on choline acetyltransferase activity and learning abilities in the rat

Young rats were treated by gastric intubation with aluminum lactate (0, 100, and 200 mg Al/kg/day) from postnatal days 5 to 14 to determine the treatment's influence on brain choline acetyltransferase activity and learning abilities. The results indicated that aluminum concentrations in the cerebral areas increased in parallel to plasma aluminum at the dose of 200 mg. In the same case, choline acetyltransferase activity was reduced. At postnatal days 50 and 100, the treated rats did not show alterations in their learning abilities in the 2 tests which are based on different motivations (avoidance of an aversive light or alimentary motivation) and different ways of achievement (pressing on a lever or running in a maze). A low reduction in the general activity, particularly in the radial maze test, was only observed in rats treated with 200 mg Al/kg/day.

Effects of combined exposure to aluminium and ethanol on aluminium body burden and some neuronal, hepatic and haematopoietic biochemical variables in the rat

The effects of the daily administration of aluminium (25 mg kg-1, orally), ethanol (10% v/v, in drinking water) or both to adult rats, for 6 weeks, on the amount of aluminium present in the tissues and the functioning of brain biogenic amines, hepatic and serum transaminases and some haematopoietic variables were investigated. Ethanol alone was seen to inhibit the activity of delta-aminolevulinic acid dehydratase (ALAD), while aluminium alone elevated the activity of blood ALAD. However, aluminium and ethanol combined produced a more pronounced inhibition of blood ALAD and hepatic glutamic pyruvic transaminase (GPT) than either aluminium or ethanol alone. Simultaneous exposure to aluminium and ethanol also produced a significant elevation in urinary delta-aminolevulinic acid (ALA) blood zinc protoporphyrin (ZPP), serum glutamic oxaloacetic transaminase (GOT) and brain homovanillic acid (HVA), and a depletion in brain dopamine (DA) and 5-hydroxytryptamine (5-HT) levels, when compared to rats given aluminium alone. The concentration of aluminium in the blood and liver was significantly higher in rats exposed to both aluminium and ethanol than in those exposed to aluminium alone. Thus the consumption of alcohol may increase the rat's susceptibility to certain effects of aluminium.

Aluminium deposition in bone after contamination of drinking water supply

Two healthy individuals who drank water accidentally contaminated at source with aluminium sulphate solution were investigated 6-7 months later. Bone biopsy specimens showed discrete lines of positive staining for aluminium, the distribution being compatible with acute exposure some months previously. These findings show that under certain conditions normal individuals can absorb aluminium via the gut, and that such aluminium can be deposited in bone.

Aluminium loading in children receiving long-term parenteral nutrition

Eight children on long-term, total parenteral nutrition (TPN) were found to have elevated aluminium (Al) levels in plasma (51 +/- 11 microg 1/1), urine (223 +/- 78 microg 24 h) and bone. The load of Al in TPN solution was 232 +/- 89 microg/day, and, among the different parenteral solution components high Al concentrations were found in amino-acids, calcium gluconate, potassium lactate, and trace elements, representing respectively 40%, 30%, 15%, and 10% of the total Al intakes. The authors conclude that children receiving long-term TPN have excessive Al intakes and are exposed to Al toxicity. The prevention of Al contamination requires careful control of the TPN components.

Aluminum speciation studies in biological fluids. Part 3. Quantitative investigation of aluminum-phosphate complexes and assessment of their potential significance in vivo

Following the discovery that specific health disorders affecting patients with renal disease were due to their excessive body accumulation of aluminum, it was established that aluminum toxicity was mainly due to the ingestion of aluminum-containing phosphate binders. Suspicion of toxicity was thus cast on aluminum-containing antacids, and subsequent tests held on healthy subjects did reveal that aluminum hydroxide gels were also potential oral sources of aluminum, especially in the presence of citric acid. Nevertheless, authors of these tests concluded that there was only marginal absorption of aluminum phosphate. In contrast with these clinical conclusions, it has recently been contended on theoretical grounds that aluminum phosphate represents a serious health hazard. To help elucidate this issue, this paper first deals with a quantitative investigation of aluminum-phosphate equilibria under physiological conditions. Then appropriate computer simulations based on corresponding results are used to assess the actual extent to which phosphate can influence aluminum bioavailability. These simulations confirm that aluminum phosphate is not expected to induce absorption of high amounts of aluminum when administered by itself. Nevertheless, this result may no longer apply in the presence of food, whose various acidic components are likely to modify the involved chemical equilibria. Moreover, it is shown that rising blood plasma phosphate levels should tend to increase aluminum tissue penetration and hence favor its potential toxicity.

Developmental alternations in offspring of female rats orally intoxicated by aluminum chloride or lactate during gestation

The oral treatment of pregnant rats by aluminum chloride or lactate at various doses was applied from day 1 to day 21 of gestation to determine its influence on mortality, weight evolution, and neuromotor maturation of their pups. No effect of treatment on litter size was detected, but an increased mortality appeared during the first week: treatment by aluminum lactate was less active than was an equivalent treatment by aluminum chloride. Weight was transitorily delayed, but the reversal of this effect could be attributed to the decrease of litter size. The neuromotor maturation of surviving pups treated with the two aluminum salts showed an important impairment during the first 2 weeks of postnatal life.

Intestinal absorption of aluminum in rats: stimulation by citric acid and inhibition by dinitrophenol

The effects of citric acid and dinitrophenol on the mucosal uptake of aluminum (Al) and its appearance in the portal and systemic blood were investigated to establish the energy dependence of these processes. Therefore, the rat small intestine was perfused in situ with media containing 20 mmol Al/liter, with or without 5 mmol citric acid/liter, and with or without 0.1 mmol/liter of the metabolic inhibitor DNP. It is concluded that (1) the appearance of Al in systemic blood depends on the mucosal Al uptake after perfusion and the systemic blood level before perfusion and (2) citric acid stimulates and DNP inhibits both mucosal uptake and Al absorption in situ.

Gastrointestinal absorption and urinary excretion of aluminium in patients with predialysis chronic renal failure

In a randomized cross-over study, serum and urinary aluminum (A1) was measured in 8 patients with predialysis chronic renal failure. Samples were taken after ingestion of an A1-containing phosphate binder (ACPB) with either water or 7% citric acid, and A1 was analyzed by electrothermal atomic absorption spectrometry. Both serum levels and urinary excretion of A1 increased markedly after ingestion of ACPB with citric acid. Only urinary A1 excretion increased significantly after ACPB with water. Citric acid alone caused no change in serum concentration or urinary excretion of A1. The serum A1 increase after ACPB with citric acid indicates that absorption of A1 is taking place in both upper and lower intestines. Marked individual variations in gastrointestinal A1 absorption, independent of kidney function, were seen after intake of ACPB with citric acid. These variations could not be predicted from changes in serum concentrations or from urinary excretion of A1 after intake of ACPB with water. Intake of ACPB caused a significant decrease in serum phosphate.

Embryotoxic and teratogenic effects of aluminum nitrate in rats upon oral administration

In order to determine the embryotoxic and teratogenic potential of aluminum, pregnant Sprague-Dawley rats were treated by gavage with a daily dose of 180, 360, or 720 mg/kg of aluminum nitrate from the sixth through to the fourteenth day of gestation. Fetal examinations were performed on day 20. The number of corpora lutea, total implants, and resorptions as well as the number of live and dead fetuses in the treated animals were not significantly different from the control group. Therefore, embryolethality of aluminum cannot be induced (as a measure of percent dead and resorbed fetuses). However, exposure of rats to aluminum nitrate resulted in decreased fetal body weight and increased the incidence and types of external, visceral, and skeletal malformations and variations in all the treated groups. Consequently, teratogenic effects of aluminum-nitrate administration may result in rats given high oral doses that induce concomitant maternal toxicity.

Comparative effects of several chelating agents on the toxicity, distribution and excretion of aluminium

The relative efficacy of citric, malic, malonic, oxalic and succinic acids, and deferoxamine mesylate (DFOA) on the toxicity, distribution and excretion in mice exposed to aluminum were compared. Chelating agents were administered intraperitoneally at a dose equal to one-fourth of their respective LD50. To determine the effect of the various chelators on the toxicity of aluminum, various doses of aluminum nitrate (938-3188 mg/kg) were administered intraperitoneally, followed by one of the chelators. Survival was recorded at the end of 14 days. Malic and succinic acids were the most effective. Malic acid and DFOA were the most effective in increasing the urinary excretion of aluminum. Citric acid was the most effective in increasing the faecal excretion of aluminum. Malonic, oxalic and succinic acids had no overall beneficial effects. Citric acid would appear to be the most effective agent of those tested in the prevention of acute aluminium intoxication. However, before the use of these compounds in human aluminium intoxication is possible, further investigations including the effects of these chelators after chronic aluminium intoxication are required.

Reduced plasma and white blood cell selenium levels in haemodialysis patients

Selenium concentrations have been measured in plasma and in blood leucocytes from 29 haemodialysis patients and from 25 healthy men. The selenium contents of the plasma and white blood cells of the dialysis patients were significantly reduced (p less than 0.001). Selenium deficiency in humans results in a congestive cardiomyopathy and is associated with increased risks of accelerated atherosclerosis and cancer. Each of these is found with abnormal frequency in haemodialysis patients.

Plasma aluminum levels in pediatric dialysis patients: comparison of hemodialysis and continuous ambulatory peritoneal dialysis

Accumulation of aluminum occurs in children with renal failure and can cause anemia, disabling osteodystrophy, and encephalopathy. Effects on bone mineralization are of particular concern in pediatric patients with growth potential. We measured plasma aluminum levels in 36 patients on continuous ambulatory peritoneal dialysis (CAPD) and 22 on hemodialysis under surveillance at a single pediatric center. The levels were above normal in 35 and 21 patients, respectively, and the values correlated with the oral dose of aluminum-containing phosphate-binding medications (r = 0.57; P less than 0.001). Younger and smaller children had higher plasma aluminum levels and also received larger doses of oral aluminum-containing compounds. Mean plasma aluminum levels (57.2 +/- 52.8 and 48.7 +/- 32.1 micrograms/liter, respectively) and the daily oral doses of elemental aluminum (47.3 +/- 37.6 and 39.2 +/- 26.7 mg/kg, respectively) were not statistically different in patients on CAPD and those on hemodialysis. Plasma aluminum levels did not correlate with estimated cumulative oral intake of aluminum, total duration of dialysis, serum calcium and phosphorus concentrations, N-terminal parathyroid hormone levels, or transfusion requirements. Retention of aluminum is common in children undergoing dialysis, correlates with the amount of aluminum administered orally, and results in similar elevations of plasma aluminum with CAPD and hemodialysis. Younger and smaller children are at increased risk for accumulation of aluminum. Alternative methods for control of serum phosphorus are needed in children with end-stage renal disease.

Neurologic development of children with severe chronic renal failure from infancy

A literature review was conducted to summarize current understanding of the effects of severe chronic renal failure (CRF), when present from infancy, on neurologic development. Data were obtained from the results of 95 examinations performed in 85 patients, most of whom had been studied after 12 months of age, or following initiation of maintenance dialysis or successful transplantation. CRF was diagnosed at birth or during the neonatal period in 71.7% of these patients; serum creatinine concentrations or calculated clearances were greater than or equal to 2.0 mg/dl (177 mumol/l) or less than 15 ml/min per 1.73 m2, respectively, in 75.8%. Head circumferences were greater than 2 standard deviations below the mean for age in 33 of 51 (64.7%) patients. Developmental delay was identified in 63.2% of all cases, and in 29 of 48 (60.4%), 16 of 19 (84.2%), and 4 of 13 (30.7%) patients studied while receiving conservative management or maintenance dialysis, or following successful transplantation, respectively. Moderate to severe delays were commoner for gross motor and language development. No significant relationships could be identified between age or severity of CRF at diagnosis and either the prevalence or severity of developmental delay. Other factors that may have contributed to observed developmental delays are also discussed, including aluminum loading, hyperparathyroidism, undernutrition, and psychosocial problems. New data are presented and discussed, and recommendations for future studies provided.

Recent advances and controversies in childhood renal osteodystrophy

Renal osteodystrophy starts very early in chronic renal failure. Although vitamin D levels are normal in patients with 70-80% function, the levels are not appropriate to the prevailing biochemical milieu. Renal osteodystrophy may contribute to renal growth failure but a correlation between the degree of renal osteodystrophy and growth failure is not observed. Catch-up growth cannot be obtained over a longer period of time with vitamin D. The main reason for osteomalacia is Al intoxication. Aluminium osteopathy is more common in pediatric renal patients than anticipated. The mechanism whereby Al produces its effect on bone is uncertain. Guidelines for the diagnosis and therapy of renal osteopathy are presented. Prophylaxis of renal osteopathy can be attempted by phosphate restriction and/or vitamin D and by avoiding Al-containing drugs. All vitamin D compounds can be used for treatment and all have their advantages and disadvantages.

Calcium carbonate is an effective phosphorus binder in children with chronic renal failure

We evaluated the effectiveness of calcium carbonate as a phosphate binder in 19 children with chronic renal failure; ten children were undergoing dialysis therapy (eight maintained by CAPD and two by hemodialysis). Twelve children had previously received aluminum hydroxide, while calcium carbonate was the primary phosphate binder used in seven children. Among all the children, the serum phosphorus level on no phosphate binder was 7.4 +/- 0.9 mg/dL, which decreased significantly (P less than .001) to 5.9 +/- 0.8 mg/dL during calcium carbonate therapy, while the serum calcium, bicarbonate, and creatinine were unchanged. The reduction in the serum phosphorus level occurred while dietary intake of calcium and phosphorus were unchanged, as demonstrated by three-day dietary records. The dose of calcium carbonate required to maintain the serum phosphorus in the normal range varied from 600 mg to 15 g/d (mean 7.4 g/d). Among the 12 children and four others who had received aluminum hydroxide, serum aluminum levels fell from 108.8 +/- 121.8 ng/mL to 36.1 +/- 29.1 ng/mL after aluminum hydroxide was stopped (P less than .05). Serum alkaline phosphatase and parathyroid hormone (PTH) levels during aluminum hydroxide therapy were similar to levels obtained during calcium carbonate therapy, while PTH levels fell in children treated initially with calcium carbonate. All the children have been observed for a mean of 12.0 months (range 4 months to 3 1/2 years). Hypercalcemia occurred in seven children, usually when vitamin D therapy was initiated or the dose changed. Hypercalcemia resolved with adjustment of the vitamin D or calcium carbonate dose in all but one patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of oral calcium carbonate on control of serum phosphorus and changes in plasma aluminum levels after discontinuation of aluminum-containing gels in children receiving dialysis

Orally administered calcium carbonate was evaluated as a phosphate binding agent in 15 children, ages 0.6 to 17.2 years, receiving maintenance dialysis. Changes in plasma aluminum concentration were assessed after discontinuation of treatment with aluminum-containing gels. The mean daily dose of calcium carbonate was 5.1 +/- 2.5 gm (384 +/- 315 mg/kg/day), and correlated inversely with body weight (r = 0.72, P less than 0.01) and age (r = 0.71, P less than 0.01). Mean serum calcium, phosphorus, and bicarbonate values were unchanged throughout the study. Plasma aluminum concentration fell from 90 +/- 51 to 34 +/- 22 micrograms/L (P less than 0.005). Dietary phosphorus intakes were 44 +/- 21 and 42 +/- 19 mg/kg/day during the control period and at the end of the study, respectively. Transitory hypercalcemia was the only side effect in 92% of the patients. In none of the patients did uncontrolled hyperphosphatemia, metabolic alkalosis, diarrhea, or symptoms or signs of hypercalcemia develop. Our data indicate that calcium carbonate is an effective phosphate binding agent in children receiving dialysis, and should be used in lieu of aluminum-containing gels in young children with renal failure.

Intestinal absorption of aluminum in rats: effect of intraluminal pH and aluminum concentration

The intestinal absorption of aluminum (Al) was studied in an in situ perfusion system of rat small intestine in combination with systemic and portal blood sampling. The jejunum-ileum was perfused with media containing 4.63, 9.25 and 18.50 mmol l-1 Al chloride at pH 4.0 and 7.0. Both mucosal retention was not affected by pH but at lower pH more Al was released into the blood. The amount of Al which appeared in the blood was linearly related to the mucosal retention. The Al release into the blood was much less (mumol l-1) than the mucosal retention (mmol l-1). It is concluded that the intestinal absorption of Al is pH- and concentration-dependent.

Intestinal absorption of aluminium from antacids: a comparison between hydrotalcite and algeldrate

The intestinal absorption of aluminium (Al) from the antacid hydrotalcite (Ultacit) was compared with that from algeldrate (Algeldratum des-acidans) in 8 healthy human subjects in a cross-over study. The level of Al in serum (AlS) was increased in 7 out of 8 subjects 7 hr after intake of 6 g algeldrate while AlS did not rise after intake of 8 g hydrotalcite--a dose with at least comparable acid-neutralizing capacity--in any of the subjects.

Suppression of secondary hyperparathyroidism in children with chronic renal failure by high dose phosphate binders: calcium carbonate versus aluminium hydroxide

Secondary hyperparathyroidism was suppressed over a period of one year in 12 children with chronic renal failure by using a regimen of mild dietary phosphate restriction and high dose phosphate binders. The patients were randomised to receive either aluminium hydroxide or calcium carbonate by mouth for six months and then crossed over to the other medication. Vitamin D (dihydrotachysterol) dosage was unchanged. Serum parathyroid hormone concentrations were reduced to within the normal range, urinary cyclic adenosine monophosphate values fell, plasma phosphate concentrations decreased, and the theoretical renal phosphate threshold increased significantly. Transiliac bone biopsy findings improved in four patients with adequate suppression of parathyroid hormone concentrations, deteriorated in two patients who were not compliant, and did not change in five patients in whom initial bone disease was mild. Growth velocity improved significantly. There was no difference in the clinical response, biochemical changes, or incidence of complications during treatment with the two agents. In view of the risk of aluminium toxicity the use of high dose calcium carbonate with dietary phosphate restriction and vitamin D supplementation is recommended in the control of secondary hyperparathyroidism in children with chronic renal failure.

Aluminium toxicity in chronic renal insufficiency

Aluminium is a ubiquitous element in the environment and has been demonstrated to be toxic, especially in individuals with impaired renal function. Not much is known about the biochemistry of aluminium and the mechanisms of its toxic effects. Most of the interest in aluminium has been in the clinical setting of the haemodialysis unit. Here aluminium toxicity occurs due to contamination of dialysis solutions, and treatment of the patients with aluminium-containing phosphate binding gels. Aluminium has been shown to be the major contributor to the dialysis encephalopathy syndrome and an osteomalacic component of dialysis osteodystrophy. Other clinical disturbances associated with aluminium toxicity are a microcytic anaemia and metastatic extraskeletal calcification. Aluminium overload can be treated effectively by chelation therapy with desferrioxamine and haemodialysis. Aluminium is readily transferred from the dialysate to the patient's bloodstream during haemodialysis. Once transferred, the aluminium is tightly bound to non-dialysable plasma constituents. Very low concentrations of dialysate aluminium in the range of 10-15 micrograms/l are recommended to guard against toxic effects. Very few studies have been directed towards the separation of the various plasma species which bind aluminium. Gel filtration chromatography has been used to identify five major fractions, one of which is of low molecular weight and the others appear to be protein-aluminium complexes. Recommendations on aluminium monitoring have been published and provide 'safe' and toxic concentrations. Also, the frequency of monitoring has been addressed. Major problems exist with the analytical methods for measuring aluminium which result from inaccurate techniques and contamination difficulties. The most widely used analytical technique is electrothermal atomic absorption spectrometry which can provide reliable measurements in the hands of a careful analyst.

Potential human health effects of acid rain: report of a workshop

This report summarizes the potential impact of the acid precipitation phenomenon on human health. There are two major components to this phenomenon: the predepositional phase, during which there is direct human exposure to acidic substances from ambient air, and the post-depositional phase, in which the deposition of acid materials on water and soil results in the mobilization, transport, and even chemical transformation of toxic metals. Acidification increases bioconversion of mercury to methylmercury, which accumulates in fish, increasing the risk to toxicity in people who eat fish. Increase in water and soil content of lead and cadmium increases human exposure to these metals which become additive to other sources presently under regulatory control. The potential adverse health effects of increased human exposure to aluminum is not known at the present time.

Influence of dietary factors on aluminium absorption and retention in the brain and bone of rats

Young adult male Sprague-Dawley rats were treated by gavage for 10 weeks (3-times weekly) with aluminium 100 mg/kg b.wt. in the form of Al-hydroxide (Novalucol), Al-citrate, Al-hydroxide together with citric acid or with tap water (controls). Male rats aged 13 months were gavaged for 11 weeks 3-times a weak with black currant soup (0.8 ml/kg b.wt.) stored 19 days in either aluminium or stainless steel saucepans. The brain cortex, bone and blood (young adults only) of each rat were analysed for Al using graphite furnace atomic absorption spectroscopy. The rats treated with Al-citrate and in particular rats treated with Al-hydroxide + citric acid showed a significant increase of Al concentrations in all the tissues studied. In the latter group the mean Al concentrations were elevated at 0.039 micrograms Al/g wet weight (controls 0.005 micrograms/g) 0.092 micrograms/g (0.016 micrograms/g) and 26.6 micrograms/g (0.22 micrograms/g) in the blood, brain and bone, respectively. After treatment with Al-hydroxide alone only the bone showed a moderate increase of Al-concentration. No significant differences were found in the brain and bone Al levels of the rats given fruit soup from aluminium saucepans (containing 17 mg Al/l) or stainless steel saucepans (0.4 mg Al/l).

Aluminum intake from non-prescription drugs and sucralfate

The use of non-prescription antacids to control hyperphosphatemia has been implicated as a primary cause of aluminum intoxications in patients with reduced renal function. Additional reports suggest that oral aluminum intake may have adverse effects on mineral metabolism of patients with normal renal function. The non-prescription drugs that contain substantial quantities of aluminum salts include some antacids, buffered aspirins, antidiarrheals, and vaginal douches. Sucralfate, an anti-ulcer drug available by prescription, is the aluminum salt of sucrose sulfate. If taken as directed, the daily aluminum intake from the antacids can be as much as 5,000 mg. When aluminum buffered aspirins are used as part of the drug therapy for rheumatoid arthritis, aluminum intake can be elevated by 700 mg/day. Although aluminum intoxications have been reported among patients with reduced renal function, existing reports are not sufficient to estimate whether the chronic elevation of aluminum intake from drugs is causing adverse health effects among other patient populations.