Aluminum hydroxide exposure induces neurodevelopmental impairment in hESC-derived cerebral organoids

Aluminum (Al) has been classified as a cumulative environmental pollutant that endangers human health. There is increasing evidence to suggest the toxic effects of Al, but the specific action on human brain development remains unclear. Al hydroxide (Al(OH)₃), the most common vaccine adjuvant, is the major source of Al and poses risks to the environment and early childhood neurodevelopment. In this study, we explored the neurotoxic effect of 5 μg/ml or 25 μg/ml Al(OH)₃ for six days on neurogenesis by utilizing human cerebral organoids from human embryonic stem cells (hESCs). We found that early Al(OH)₃ exposure in organoids caused a reduction in the size, deficits in basal neural progenitor cell (NPC) proliferation, and premature neuron differentiation in a time and dose-dependent manner. Transcriptomes analysis revealed a markedly altered Hippo-YAP1 signaling pathway in Al(OH)₃ exposed cerebral organoid, uncovering a novel mechanism for Al(OH)₃-induced detrimental to neurogenesis during human cortical development. We further identified that Al(OH)₃ exposure at day 90 mainly decreased the production of outer radial glia-like cells(oRGs) but promoted NPC toward astrocyte differentiation. Taken together, we established a tractable experimental model to facilitate a better understanding of the impact and mechanism of Al(OH)₃ exposure on human brain development.

Hollow Aluminum Hydroxide Modified Silica Nanoadjuvants with Amplified Immunotherapy Effects through Immunogenic Cell Death Induction and Antigen Release

In spite of the widespread application of vaccine adjuvants in various preventive vaccines at present, the existing adjuvants are still hindered by weak cellular immunity responses in therapeutic cancer vaccines. Herein, a hollow silica nanoadjuvant containing aluminum hydroxide spikes on the surface (SiAl) is synthesized for the co-loading of chemotherapeutic drug doxorubicin (Dox) and tumor fragment (TF) as tumor antigens (SiAl@Dox@TF). The obtained nanovaccines show significantly elevated anti-tumor immunity responses thanks to silica and aluminum-based composite nanoadjuvant-mediated tumor antigen release and Dox-induced immunogenic cell death (ICD). In addition, the highest frequencies of dendritic cells (DCs), CD4⁺ T cells, CD8⁺ T cells, and memory T cells as well as the best mice breast cancer (4T1) tumor growth inhibitory are also observed in SiAl@Dox@TF group, indicating favorable potential of SiAl nanoadjuvants for further applications. This work is believed to provide inspiration for the design of new-style nanoadjuvants and adjuvant-based cancer vaccines.

Mechanisms of Antigen Adsorption Onto an Aluminum-Hydroxide Adjuvant Evaluated by High-Throughput Screening

The adsorption mechanism of antigen on aluminum adjuvant can affect antigen elution at the injection site and hence the immune response. Our aim was to evaluate adsorption onto aluminum hydroxide (AH) by ligand exchange and electrostatic interactions of model proteins and antigens, bovine serum albumin (BSA), β-casein, ovalbumin (OVA), hepatitis B surface antigen, and tetanus toxin (TT). A high-throughput screening platform was developed to measure adsorption isotherms in the presence of electrolytes and ligand exchange by a fluorescence-spectroscopy method that detects the catalysis of 6,8-difluoro-4-methylumbelliferyl phosphate by free hydroxyl groups on AH. BSA adsorption depended on predominant electrostatic interactions. Ligand exchange contributes to the adsorption of β-casein, OVA, hepatitis B surface antigen, and TT onto AH. Based on relative surface phosphophilicity and adsorption isotherms in the presence of phosphate and fluoride, the capacities of the proteins to interact with AH by ligand exchange followed the trend: OVA < β-casein < BSA < TT. This could be explained by both the content of ligands available in the protein structure for ligand exchange and the antigen's molecular weight. The high-throughput screening platform can be used to better understand the contributions of ligand exchange and electrostatic attractions governing the interactions between an antigen adsorbed onto aluminum-containing adjuvant.

Chemical mimicking of bio-assisted aluminium extraction by Aspergillus niger's exometabolites

Presence of microorganisms in soils strongly affects mobility of metals. This fact is often excluded when mobile metal fraction in soil is studied using extraction procedures. Thus, the first objective of this paper was to evaluate strain Aspergillus niger's exometabolites contribution on aluminium mobilization. Fungal exudates collected in various time intervals during cultivation were analyzed and used for two-step bio-assisted extraction of alumina and gibbsite. Oxalic, citric and gluconic acids were identified in collected culture media with concentrations up to 68.4, 2.0 and 16.5 mmol L^-1, respectively. These exometabolites proved to be the most efficient agents in mobile aluminium fraction extraction with aluminium extraction efficiency reaching almost 2.2%. However, fungal cultivation is time demanding process. Therefore, the second objective was to simplify acquisition of equally efficient extracting agent by chemically mimicking composition of main organic acid components of fungal exudates. This was successfully achieved with organic acids mixture prepared according to medium composition collected on the 12th day of Aspergillus niger cultivation. This mixture extracted similar amounts of aluminium from alumina compared to culture medium. The aluminium extraction efficiency from gibbsite by organic acids mixture was lesser than 0.09% which is most likely because of more rigid mineral structure of gibbsite compared to alumina. The prepared organic acid mixture was then successfully applied for aluminium extraction from soil samples and compared to standard single step extraction techniques. This showed there is at least 2.9 times higher content of mobile aluminium fraction in soils than it was previously considered, if contribution of microbial metabolites is considered in extraction procedures. Thus, our contribution highlights the significance of fungal metabolites in aluminium extraction from environmental samples, but it also simplifies the extraction procedure inspired by bio-assisted extraction of aluminium by common soil fungus A. niger.

In end-stage renal failure, does infection lead to elevated plasma aluminium and neurotoxicity? Implications for monitoring

The well-described long-term effects of sustained exposure to aluminium in patients with end-stage renal failure (ESRF) are a result of uptake and storage of aluminium, leading to cellular toxicity. A case is presented suggesting that this aluminium may be mobilizable, and indicating the consequence of such release.

A patient on haemodialysis (HD) presented acutely with infection, a raised CRP, decreased conscious level, impaired cognition and agitation. Subsequent neurological recovery over six to seven days appeared to follow the return of markedly elevated plasma aluminium concentrations to basal (i.e. from 25.2 μmol/L to 2.5 μmol/L; reference range <0.5 μmol/L), coupled with a resolution of the infection. The patient was on long-term aludrox therapy 3 g/day, and showed relative resistance to the exogenous hormone erythropoietin, resulting in a refractory anaemia and suggesting aluminium toxicity. A series of HD patients ( n=5) presenting with bacteraemia, not on aludrox, showed no appreciable rise in the plasma aluminium mean of 1.3 μmol/L (SD 0.9; range 0.6-2.0 μmol/L). We suggest that infection can result in release of tissue aluminium, leading to acutely elevated plasma aluminium concentrations and signs of neurotoxicity. The amount of tissue storage and resultant aluminium release seemed to be related to the use of aluminium hydroxide as a phosphate binder.

Wet air oxidation and catalytic wet air oxidation for dyes degradation

BACKGROUND, AIM, AND SCOPE

Textile industry produces wastewater which contributes to water pollution since it utilizes a lot of chemicals. Preliminary studies show that the wastewater from textile industries contains grease, wax, surfactant, and dyes. The objective of this study was to determine the treatment efficiency of the nickel catalysts supported on hydrotalcites in three-dye model compounds and two types of wastewater.

MATERIALS AND METHODS

Hydrotalcites were employed to prepare supported nickel catalysts by wetness impregnation technique. Metal loadings from 1 to 10 wt% were tested. Catalysts were characterized by several techniques. They were tested in a catalytic wet air oxidation of three dyes and two wastewaters with different origins.

RESULTS AND DISCUSSION

It could be observed that the higher the metal content, the lower the BET area, possibly due to sintering of Ni and the consequent blocking of the pores by the metal. In addition, metallic dispersion was also higher when the metal content was lower. Dye conversion was more than 95% for every catalyst showing no differences with the nickel content. A high degree of dye conversion was achieved. Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) processes have been proved to be extremely efficient in TOC removal for wastewaters.

CONCLUSIONS

The CWAO process can be used to remove dyes from wastewater. Three different dyes were tested showing satisfactory results in all of them. TOC degradation and dye removal in the presence of the catalyst were effective. Also, the HTNi catalyst is very active for organic matter and toxicity removal in wastewaters.

Aluminum uptake and disease resistance in Nicotiana rustica leaves

The comparative effectiveness of aluminum hydroxide and aluminum chloride has been studied in the development of bacterial wilt infection on leaves of Nicotiana rustica cv. Gansu yellow flower. We have analyzed the changes of foliar H(2)O(2) content, as well as of non-enzymatic and enzymatic antioxidants under aluminum stress. Pretreatment with aluminum hydroxide before pathogen challenge reduced the development of Ralstonia solanacearum infection and decreased the extent of leaf injury. The pretreatment also reduced the Al uptake in comparison to pretreatment with aluminum chloride. H(2)O(2) generation was significantly enhanced by pretreatment with aluminum hydroxide. Increased NADPH oxidase and superoxide dismutase activities were correlated with limited infection. Aluminum hydroxide pretreatment shifted the leaf redox homeostasis of AsA/DHA and GSH/GSSG toward oxidation, yielding higher oxidant levels than aluminum chloride before bacterial inoculation. The results support the idea that aluminum hydroxide induced H(2)O(2) accumulation through non-enzymatic and enzymatic regulation, ultimately resulting in resistance to tobacco wilt disease.

[Microbial reduction and mobilization of adsorbed arsenate on ferric/aluminum hydroxides]

Although the mechanisms of arsenic release into groundwater remain poorly characterized, microbial reduction of As (V) adsorbed on the surface of iron oxides and the reductive dissolution of iron oxides are generally considered to play a key role in the mobilization of arsenic. We investigated the impact of bacterial reduction of adsorbed As (V) on a Al:Fe (1:0, 1:1, 0:1) hydroxides on arsenic mobilization using the mixed bacterial culture. After inoculation, the increase of dissolved As (III) concentration was observed, whereas As (V) was negligible in aqueous phase. Arenic release for the Al:Fe (1:0, 1:1, 0:1) hydroxides systems was 60 microg/L, 1.3 mg/L and 7.8 mg/L respectively. On the contrary, neither reduction nor release of arsenic was observed in the uninoculated groups. Furthermore, the introduction of aluminium may be responsible for the release of arsenic owing to its weaker affinity to As (III). In addition, our results showed that Fe reduction occurred far later than arsenic reduction and mobilization and obvious increase was not observed even after Fe reduction occurred. It suggested that in natural systems, the biotic reduction of As (V) adsorbed on ferric oxides or Fe (III) may not the major cause of arsenic release in sediment or groundwater system as previous works proposed. The reduction of As (V) bound to aluminum oxides or other minerals may play a key role.

Bioaccumulation of heavy metals by Phragmites australis cultivated in synthesized substrates

Accumulation of heavy metals from various oxides with adsorbed cadmium by wetland plant Phragmites australis was studied to evaluate the fate of heavy metals in the sediment of constructed wetlands. Hoagland solution was used as nutrition supply, and single metal oxide with adsorbed cadmium was applied as contaminant to study the accumulation characteristics of cadmium and the substrate metals by P. australis. After 45-d treatment, the bioaccumulation degree in root followed the order: Al(OH)3 > Al2O3 > Fe3O4 > MnO2 > FeOOH. Heavy metals absorbed by P. australis were largely immobilized by the roots with little translocation to aboveground parts.

Transesterification of triglycerides in high and low quality oil feeds over an HT2 hydrotalcite catalyst

The use of a heterogeneous catalyst, in the transesterification reaction of refined and acidic cottonseed oil for the production of methyl-esters (biodiesel) has been studied. The basic Mg-Al-CO3 hydrotalcite catalyst used showed a high activity for methanolysis and esterification reactions in a refined and an acidic cottonseed oil as well as in a representative high water content animal fat feed. The experiments were performed in a temperature range between 180 and 210 degrees C, in a batch reactor. The methanol to vegetable oil molar ratio was 6 to 1, while the catalyst concentration was fixed at 1 wt.% of the oil mass. Non-calcined and calcined forms of the catalyst were tested. The activity of the calcined catalyst was lower than the initial activity of the non-calcined catalytic system but it appeared the same with the reused non-calcined system.

Effects of acute exposure to aluminum on cognition in humans

There is epidemiological evidence suggesting an association between aluminum in drinking water and Alzheimer's disease (AD), and between aluminum in dialysate and dialysis dementia. The exact role of aluminum in the pathogenesis of these and other dementias is not clear. This study examined the acute effects of aluminum on cognitive function in patients with AD and related dementias and in age-matched and younger volunteers with normal cognitive function. Whether individuals with AD and/or the APOE epsilon4 genotype had enhanced gastrointestinal absorption of aluminum was tested, and whether individuals with elevated blood aluminum concentrations exhibited acute cognitive effects was determined. Subjects were randomized to receive a single dose of aluminum orally (Amphojel plus citrate) for 3 d followed by a 3-wk washout, and then 3 d of matched placebo administration, or vice versa. Serum aluminum levels were measured and the daily dose of Amphojel was adjusted to a target aluminum level between 50 and 150 microg/L. Neuropsychological tests were administered at baseline and 90 min after the third dose of Amphojel or placebo. There was a large interindividual variation in aluminum serum levels in all study groups after the same initial dose of Amphojel. There were no significant differences in neuropsychological test scores after aluminum ingestion in normal volunteers or in patients with cognitive impairment. There was no association between APOE epsilon4 genotype and aluminum absorption. The results did not support the hypothesis that aluminum ingested at these doses produces acute effects on cognition or adverse effects, nor did they reveal that AD patients are more vulnerable to such outcomes. Further inquiry is required to explore any possible association between aluminum and cognition, but controlled trials may be limited by safety concerns.

Anionic clays for sunscreen agent safe use: Photoprotection, photostability and prevention of their skin penetration

The use of sunscreen preparations is recently growing and their efficacy and safety must be taken into account since they are applied on the skin frequently and for many hours. Exposition to sunlight, in fact, can cause sunscreen photodegradation and determine their decrease in UV protection often with the occurrence of allergic and/or toxic degradation products. A high photostability is hence very important for their effectiveness and safety. The aim of this work is to obtain new sunscreen formulations stabilized by intercalating PABA, within the lamellar structures of two kinds of hydrotalcite. PABA was chosen as model sunscreen because of its high photoinstability and photosensitizing properties that nowadays bar its utilization. Both intercalated products showed an increased protection range and, in one case, an improved sunscreen photostability. Sunscreen release from creams containing intercalated or free PABA was evaluated as well. The very low or negligible sunscreen release, obtained from the intercalated product loaded formulations, resulted in a lack of a close contact between skin and filter with the consequence that cutaneous reactions and allergy problems are eliminated. The use of these materials resulted in a good strategic technological approach in order to increase efficacy and safety of solar products.

Aluminum control of phosphorus sorption by lake sediments

Release of reactive (phosphate-like) phosphorus (P) from freshwater sediments represents a significant internal P source for many lakes. Hypolimnetic P release occurs under reducing conditions that cause reductive dissolution of ferric hydroxide [Fe(OH)3]. This hypolimnetic P release may be naturally low or artificially reduced by sediment with naturally high or artificially elevated concentrations of aluminum hydroxide [Al(OH)3]. We presentfield and laboratory data for a common extraction analysis of sediments from 43 lakes differing in trophic status, pH regime, climate, and P loading. The results indicate that a simple sequential extraction of sediment may be a useful predictor of sediment's ability to release P. Sequential extractions of sediment P, Al, and Fe by water (H2O), bicarbonate-dithionite (BD), and NaOH (at 25 degrees C) showed that negligible amounts of P would be released from lake sediments during hypolimnetic anoxia if either (1) the molar Al(NaOH-25):Fe(BD) ratio is > 3 or (2) the molar Al(NaOH-25):P(H2O+BD) ratio is > 25. These ratios can be used as operational targets for estimation of sediment P release potential and Al dosing of P-rich sediment to prevent hypolimnetic P release under anoxic conditions.

Protection by natural human immunoglobulin M antibody to meningococcal serogroup B capsular polysaccharide in the infant rat protection assay is independent of complement-mediated bacterial lysis

Neisseria meningitidis, an important cause of bacterial meningitis and septicemia worldwide, is associated with high mortality and serious sequelae. Natural immunity against meningococcal disease develops with age, but the specificity and functional activity of natural antibodies associated with protection are poorly understood. We addressed this question by using a selected subset of prevaccination sera (n = 26) with convergent or discrepant serum bactericidal activity (SBA) and infant rat protective activity (IRPA) against the serogroup B meningococcal strain 44/76-SL (B:15:P1.7,16) from Icelandic teenagers. The sera were analyzed by opsonophagocytic activity (OPA) assay, immunoblotting, immunoglobulin G (IgG) quantitation against live meningococcal cells by flow cytometry, and enzyme immunosorbent assay (EIA). High levels of SBA and OPA were reflected in distinct IgG binding to major outer membrane proteins and/or lipopolysaccharide in immunoblots. However, we could not detect any specific antibody patterns on blots that could explain IRPA. Only IgM antibody to group B capsular polysaccharide (B-PS), measured by EIA, correlated positively (r = 0.76, P < 0.001) with IRPA. Normal human sera (NHS; n = 20) from healthy Finnish children of different ages (7, 14, and 24 months and 10 years) supported this finding and showed an age-related increase in IRPA that coincided with the acquisition of B-PS specific IgM antibody. The protection was independent of complement-mediated bacterial lysis, as detected by the inability of NHS to augment SBA in the presence of human or infant rat complement and the equal protective activity of NHS in rat strains with fully functional or C6-deficient complement.

Spectroscopic characterization of antibodies adsorbed to aluminium adjuvants: correlation with antibody vaccine immunogenicity

MMA383 is an anti-idiotypic antibody designed as an immunogenic surrogate for the cancer specific Lewis Y antigen. Lewis Y is expressed in 70-90% of tumours of epithelial origin with limited expression in normal tissue. Five different MMA383 vaccines were prepared by mixing a MMA383 antibody solution with an Alhydrogel aluminium hydroxide adjuvant and tested on the biological activity in a rat model. The immunogenicity increased when: (i) the adjuvant was sterilized at 121 degrees C compared to no sterilization, (ii) the adjuvant was suspended in a phosphate buffer compared to water and (iii) the MMA383 solution was at a pH of 7.2. The immunogenicity of a ready-to-use MMA383 aluminium hydroxide suspension was the lowest. The in vivo data show that small differences in vaccine formulations before injection can generate significant changes in immunogenicity. Prior to mixing with the adjuvant, the physical and chemical characteristics of MMA383 antibodies were the same in all vaccines. Fluorescence and light scattering methods were developed to characterize antibodies in the presence of the adjuvant. Compared to the least active vaccines, the two most biologically active vaccines showed an increase in the antibody Trp fluorescence intensity, anisotropy, fluorescence lifetime, 90 degrees light-scatter, sedimentation velocity and rotational correlation time. Analysis of the 90 degrees light-scatter sedimentation kinetics indicates that stronger immune responses of vaccines can be related to the stronger binding of the antibodies to the adjuvants and the formation of more compact and condensed particles. Taken together, these results show a correlation between the in vitro fluorescence and light-scatter data and the in vivo immune response of the five MMA383 vaccines. The spectroscopic techniques described offer a new in vitro approach for the prediction of immune responses of different vaccine formulations.

Cross-reactivity and inhibition of haemolysis by polyclonal antibodies raised against St II, a cytolysin from the sea anemone Stichodactyla helianthus

The immunogenicity of sticholysin II (St II), a pore-forming polypeptide from the sea anemone Stichodactyla helianthus, was studied in rabbits using two adjuvants, Freund's and aluminium hydroxide. High titres of antibodies were raised against St II with Freund's adjuvant (FA). The structural homology between sticholysins I and II was also revealed by cross-reactivity assays. Since the oil constituent of FA neutralized the St II haemolytic activity, immunizations with St II-Freund's emulsions were carried out with the inactivated cytolysin. Purified anti-St II IgG also neutralized the St II haemolytic activity.

Aluminum phagocytosis in quadriceps muscle following vaccination in children: relationship to macrophagic myofasciitis

Macrophagic myofasciitis (MMF) is a rare, seemingly emerging entity among adult patients in France. We encountered two children with the first two cases of MMF in North America. A 5-year-old male with chronic intestinal pseudo-obstruction required nighttime parenteral nutrition. Abnormal pupillary reflexes and urinary retention suggested a diffuse dysautonomia, which prompted a neurological diagnostic work-up. A 3-year-old child had developmental delay and hypotonia. Both children received age-appropriate immunizations. Quadriceps muscle biopsy from each child showed the typical patchy, cohesive centripetal infiltration of alpha-1-antitrypsin+, alpha-1-antichymotrypsin+, CD68+, PAS+, CD1a-, S-100-, factor XIII- granular macrophages with adjacent myofiber atrophy, dilated blood vessels, and mild endomysial and perimysial fibrosis. No myonecrosis was observed and no discrete granulomas were seen. A single aluminum peak was demonstrated on energy dispersive X-ray microanalysis. The etiology of the clinical symptoms in these cases and in cases reported as MMF remains intriguing. Despite numerous stains to demonstrate organisms, most infectious causes leading to macrophage activation were ruled out. These cases are being reported to increase awareness of this condition and to encourage a systematic epidemiologic and clinicopathologic study in North America.

The influence of PAX-14 on activated sludge systems and in particular on Microthrix parvicella

The amount of wastewater treatment plants (WWTP) dealing with solid separation problems has significantly increased since the new requirements of the EU Directive 271/91 on nutrient removal. In Flanders a number of the nutrient removal WWTP are affected by solid separation problems mostly attributed to Microthrix parvicella being the most common dominant species. The effect of dosing polyaluminium chloride (PAX-14) on activated sludge is illustrated for WWTP solids separation problems, in particular because of Microthrix parvicella. The effects of the addition of PAX-14 on the microbiology and the morphology of Microthrix parvicella were studied in 9 full-scale WWTP. PAX-14 succeeded in reducing high SVI-values and controlled foaming problems whenever caused by Microthrix parvicella. Laboratory trials have shown that the dosage of PAX-14 should be less than 150 microL/L or 7 g Al3+/kg MLSS. At a dosage higher than 250 microL/L, an increase of free bacteria and a decrease of the protozoa activity are observed. In full-scale, PAX-14 is dosed at a concentration of 1.5 to 4.5 g Al3+/kg MLSS. Before addition, the mixed liquor scum layer--if present--should be removed. In our experience, the dosing should last for at least 3 weeks. During the first week, no drastic changes occur. At the end of the first week, an increase of SS and SVI is possible. The SVI and scum start to decrease after 10 to 15 days. The amount of filaments is reduced after 3 to 3 1/2 weeks. The morphological properties of Microthrix parvicella change, while other filaments such as Nostocoida limicola and Nocardia spp. are not affected. This study proves that PAX-14 is effective in controlling bulking and foaming problems at WWTPs when they are due to Microthrix parvicella. Prediction of when the SVI will decrease and when addition should be stopped is possible.

Detoxification of endotoxin by aluminum hydroxide adjuvant

Langmuir adsorption isotherms of endotoxin and aluminum-containing adjuvants at pH 7.4 and 25 degrees C revealed that aluminum hydroxide adjuvant has a greater adsorption capacity (283 microg/mg Al) and adsorption coefficient (1.3x10(4) ml/miccrog) than aluminum phosphate adjuvant (3.0 microg/mg Al, 0.20 ml/microg). The difference in endotoxin adsorption was related to two adsorption mechanisms: electrostatic attraction and covalent bonding. The isoelectric point (iep) of endotoxin is approximately 2. An electrostatic attractive force will be present with aluminum hydroxide adjuvant (iep=11.4), and an electrostatic repulsive force will operate with aluminum phosphate adjuvant (iep=4.6). Endotoxin contains two phosphate groups in the lipid A portion. Covalent bonding occurs with surface aluminum in aluminum hydroxide adjuvant but is inhibited by surface phosphate in aluminum phosphate adjuvant. In-vitro desorption experiments using components of interstitial fluid showed that endotoxin adsorbed by aluminum hydroxide adjuvant was not desorbed by interstitial anions (5 mM phosphate or 2.7 mM citrate) or interstitial proteins (25 mg albumin/ml). The effect of aluminum-containing adjuvants on the systemic response of Sprague-Dawley rats to a 15 microg/kg subcutaneous dose of endotoxin was determined by measuring the serum concentration of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). TNF-alpha and IL-6 were observed in the group which received an endotoxin solution or endotoxin and aluminum phosphate adjuvant. No TNF-alpha or IL-6 was detected in the group that received endotoxin and aluminum hydroxide adjuvant. Aluminum hydroxide adjuvant detoxifies endotoxin by adsorbing it in the vaccine and then not releasing it in interstitial fluid upon administration.

Mechanisms of aluminum absorption in rats

Aluminum has become a dietary toxin in modern times but its mechanism of absorption is poorly understood. After ingestion, the systemic transfer of aluminum is small but it is greatly affected by the coingestion of certain dietary agents, such as citrate, that complex with the metal in the intestinal lumen or transiently alter the permeability of the mucosa. Here, mechanisms of aluminum absorption were studied by using freshly prepared aluminum hydroxide and aluminum citrate. Everted sacs of rat gut were used to investigate the site of absorption, effect of chemical charge on absorption of aluminum citrate, and presence of active or passive absorption with use of the metabolic inhibitor ouabain. Absorption was biphasic with a large tissue uptake that was consistent with adhesion to mucus-mucosal surface but little tissue transport, which was consistent with passive paracellular permeation. Citrate reduced the uptake-transport ratio both by competing with the mucosal uptake and by increasing mucus-mucosal permeation but not by affecting the charge of the luminal aluminum species. Despite the potential for hydroxypolymerization of aluminum at intestinal pH, the small bowel and colon absorbed aluminum passively and paracellularly but the stomach did not. The predominantly proximal absorption of aluminum observed in vivo is a reflection of the proximal absorption, and therefore removal, of dietary constituents (eg, citrate) that enhance mucosal permeation of aluminum. The colon should be investigated further as a site of significant paracellular permeability.

The bioavailability of 26Al-labelled aluminium citrate and aluminium hydroxide in volunteers

A study was undertaken to determine the fraction of ingested aluminium taken up by two male volunteers, following their ingestion of either aluminium citrate or aluminium hydroxide. In addition, the effects of simultaneous citrate ingestion on the gastrointestinal absorption of aluminium from its hydroxide was studied. Volunteers received three oral doses of 26Al-labelled aluminium compound in water. The doses were administered directly into the stomach using a paediatric feeding tube. Blood samples were collected from the volunteers at 1, 4 and 24 h after administration, and their daily output of urine and faeces was collected for 6 days. These samples were analysed for their 26Al content using either coincidence gamma-counting or accelerator mass spectrometry. The uptake of aluminium was greatest following its administration in the citrate form and was least following intake as the aluminium hydroxide suspension. The co-administration of citrate, with the aluminium hydroxide suspension, was found to enhance the levels of 26Al uptake in both volunteers. Using a urinary excretion factor based on the results of previous studies, the fractional aluminium uptake from each of the species was calculated: aluminium citrate, 5.23 x 10(-3); aluminium hydroxide, 1.04 x 10(-4); aluminium hydroxide with citrate, 1.36 x 10(-3).

Adjuvanticity of aluminium hydroxide and calcium phosphate in diphtheria-tetanus vaccines--I

The potencies of two diphtheria-tetanus vaccines (DT) adsorbed to either aluminium hydroxide or calcium phosphate were compared in mice and guinea pigs. The vaccines were made from the same batches of purified toxoids and contained the same amounts of antigens. Immunizations were done once or twice with different doses of vaccine injected undiluted, diluted in saline or diluted in the corresponding adjuvant. The various potency assays showed that the adjuvanticity of calcium phosphate was lower than or equal to aluminium hydroxide. Despite the range of potency assays done, none of the methods reflected the efficacy of these vaccines in revaccination of humans. A simplified potency assay is suggested for release of final vaccine formulations to reduce the number of animals in quality control.

Concurrent ingestion of lactate and aluminum can result in developmental toxicity in mice

The influence of lactate on the potential developmental toxicity of high doses of aluminum (57.5 mg/kg/day) was evaluated. Three groups of pregnant Swiss mice were given by gavage daily doses of Al(OH)3 (166 mg/kg), aluminum lactate (627 mg/kg), or Al(OH)3 (166 mg/kg) concurrent with lactic acid (570 mg/kg) on gestational days 6-15. An additional group of pregnant mice received lactic acid (570 mg/kg) during the same period. Cesarean sections were performed on gestation day 18, and live fetuses were sexed, weighed and examined for morphological defects. Maternal toxicity was observed in the groups treated with aluminum lactate, and Al(OH)3 concurrent with lactic acid. The reproductive data did not show embryotoxic effects in any group, whereas fetal body weight was significantly reduced in the aluminum lactate group. In this group, morphological changes included cleft palate and an increased incidence of parietals with delayed ossification. Although not statistically significant, the incidence of skeletal variations was also increased in the group given Al(OH)3 concurrent with lactic acid. Taken together the present data, as well as the results of previous studies strongly suggest that the consumption of high doses of aluminum-containing compounds should be avoided during pregnancy.

Pharmacokinetics of cefpodoxime proxetil and interactions with an antacid and an H2 receptor antagonist

Cefpodoxime proxetil is a new oral esterified cephem antibiotic with a broad antibacterial spectrum. The dissolution of cefpodoxime proxetil is pH dependent. The objectives of this study were to characterize the pharmacokinetics of cefpodoxime proxetil in two different oral doses and to examine possible interactions with an antacid, aluminum magnesium hydroxide (Maalox 70), and an H2 receptor antagonist, famotidine. Two studies involving the same 10 healthy volunteers were performed. In the first study, cefpodoxime proxetil was administered in two doses, 0.1 and 0.2 g. In the second study, two interventions were performed in a randomized crossover design. For one intervention, the volunteers were pretreated with 40 mg of famotidine 1 h before 0.2 g of cefpodoxime proxetil was administered. In the second trial, participants were given 10 ml of Maalox 70 2 h and 10 ml of Maalox 70 15 min before they received 0.2 g of cefpodoxime proxetil. Serum and urine concentrations were determined by high-performance liquid chromatography. For the statistical evaluation, these data were tested by using the pharmacokinetics of 0.2 g of cefpodoxime proxetil from the first study. The maximum concentrations were 1.19 +/- 0.32 mg/liter after 0.1 g of cefpodoxime proxetil and 2.54 +/- 0.64 mg/liter after 0.2 g of cefpodoxime proxetil. The elimination half-lives were 149 min for 0.1 g and 172 min for 0.2 g of cefpodoxime proxetil. The total increase in the area under the concentration-time curve (AUC) was dose dependent. Combination with Maalox 70 caused a reduction in the AUC from 14.0 +/- 3.9 to 8.44 +/- 1.85 mg.h/liter. After famotidine, the AUC decreased to 8.36 +/- 2.0 mg . h/liter. Corresponding changes were registered for the maximum concentration of drug in serum, 24-h urine recovery, and the time to maximum concentration of drug serum. Cefpodoxime proxetil was well tolerated without any seriously adverse drug reactions.

Autonomous hyperparathyroidism not associated with increased aluminum absorption

A single 6-g dose of aluminum hydroxide was given to eight patients on regular hemodialysis before and 3 days after parathyroidectomy (PTX). Serum aluminum levels were measured before and after 5 h after ingestion of aluminum hydroxide to examine indirectly the effects on absorption of aluminum from the gastrointestinal tract of both high and low parathyroid hormone (PTH). Plasma PTH levels fell significantly from 2,724 +/- 1,830 ng/l (mean +/- 1 SD) before PTX to 352 +/- 63 ng/l after PTX. However, no significant change was detected in serum aluminum levels before or after PTX (1.45 +/- 0.96 to 1.92 +/- 0.88 mumol/l before PTX; 2.02 +/- 1.41 to 2.89 +/- 1.19 mol/l after). These findings indicate that in patients with chronic renal failure, high plasma levels of PTH are not associated with significant increases in serum aluminum concentrations after ingestion of a large quantity of aluminum hydroxide. Parathyroid hormone may not enhance intestinal absorption of aluminum in humans.

Morphologic and ultrastructural effects of Maalox TC on human gastric and duodenal mucosa

Prostaglandins (PGs) and aluminum-containing antacids (Al.AAs) are effective in preventing gastric and duodenal lesions induced by neutralizing agents. The efficacy of Al.AAs is thought to be due to neutralizing properties and to stimulation of endogenous PGs synthesis. Liquid Maalox has the same effect as cimetidine 400 mg on postprandial duodenal acid load. In numerous prospective studies, Al.AAs have been shown to be as effective as cimetidine in the short-term treatment of duodenal ulcer (DU). Maalox TC at a dosage of 3 tablets b.i.d. provides an effective method for preventing DU relapse. Its effect is similar to that of nighttime cimetidine. Meta-analysis of prospective trials suggests that Al.AAs prevent stress ulcers more effectively than does cimetidine. It has been suggested that Al.AA acts by inducing surface epithelial cell disruption. Al-induced mucosal protection could be caused by a stimulated release of endogenous PGs, induced by Al microcrystal penetration of cells. In a recent study, we showed that small amounts of Al were absorbed by human gastric mucosa and accumulated in lysosomes; however, we did not observe any histological or ultrastructural lesions of the gastric mucosa. Prostaglandins (enprostil, misoprostol, and rioprostil) are as effective as cimetidine, but less effective than ranitidine, in healing DU. Enprostil and rioprostil have been shown to be as effective as ranitidine in treating gastric ulcer (GU). Moreover, enprostil inhibits postprandial gastrin release, whereas H2-blockers increase gastrin levels. Coadministration of misoprostol with aspirin is highly effective in healing aspirin-induced gastroduodenal lesions. Moreover, cotreatment with misoprostol was associated with a marked decrease in GU in patients with osteoarthritis receiving NSAIDs chronically.(ABSTRACT TRUNCATED AT 250 WORDS)

Mucosal injury and gamma-irradiation produce persistent gastric ulcers in the rabbit. Evaluation of antiulcer drug binding to experimental ulcer sites

A method producing persistent gastric ulcers in the rhesus monkey by combined mucosal injury and gamma-irradiation was modified and evaluated in the rabbit. gamma-Irradiation (800-1000 cGy) immediately after removal of 2-mm-diameter sections of antral mucosa resulted in ulcer craters 5-7 days later. Ulcer sites were characterized by loss of the mucosa, muscularis mucosa, and much of the submucosa. The exposed submucosa was coated with fibrin and necrotic debris infiltrated with heterophils, the rabbit equivalent of neutrophils. These ulcers strongly resemble human chronic gastric ulcers. Binding of Carafate (sucralfate; Marion Laboratories, Inc., Kansas City, MO) and Maalox (magnesia-alumina oral suspension; Wm. H. Rorer, Inc., Ft. Washington, PA) to ulcer and nearby nonulcer sites in the antrum was assessed 1 hour after drug dosing. Drug binding was determined by aluminum quantitation of stomach wall punch biopsies at necropsy. Both drugs significantly increased aluminum bound to the stomach wall compared with vehicle treatment. Significantly more antiulcer drug was bound to ulcer sites than to nearby nonulcer sites only after sucralfate administration. This model of persistent gastric ulcer should be useful to further study gastric ulcer pathogenesis and treatment.

Bile salt binding by maalox, sucralfate, and meciadanol: in vitro and clinical comparisons

Inhibition of gastric acid secretion is a major factor in protecting the gastric mucosa, although other mechanisms such as bile salt binding may contribute to the protective properties of individual agents. Sucralfate, antacid (Maalox), and Meciadanol, a new flavonoid, were compared with cholestyramine resin for binding bile salts. The free, glycine, and taurine conjugates of the human bile salts, cholate, chenodeoxycholate, and deoxycholate, were incubated with each of the above. Cholestyramine resin adsorbed 91-97% of all bile salts tested. Meciadanol adsorbed all of the bile salts fairly well except for the free forms of chenodeoxycholate and deoxycholate. Meciadanol (53 to 84%) adsorbed bile salts better than sucralfate (4.2 to 61%), and significantly (P less than 0.05) better than Maalox (10 to 47%). In our in vitro studies, sucralfate was not as effective in binding bile salts as previously reported. Patients in the surgical intensive care unit were randomized prospectively to receive nasogastric instillation of Maalox, sucralfate, or Meciadanol to prevent gastrointestinal bleeding. The gastric aspirates were analyzed for bile salt concentration. The mean bile salt concentration of those treated with Maalox (0.24 mM), Meciadanol (0.24 mM), or sucralfate (0.35 mM) was significantly lower than those treated with nasogastric aspiration (0.87 mM) alone (P less than 0.01). This suggests that these substances bind bile salts and may provide additional protection to the gastric mucosa along with their ability to neutralize gastric acid.

Serum aluminium level in the veneto chronic haemodialysis population: cross-sectional study on 1,026 patients

A total of 1,026 patients undergoing haemodialysis as the only chronic treatment were studied in all the dialysis units of the Veneto region, Italy. Aluminium was determined in water, dialysis fluids, and patients' serum. Aluminium mean concentration was 9.1 micrograms/l in tap water and 13.3 and 15.7 micrograms/l in bicarbonate and acetate haemodialysis fluids, respectively. Patients' serum aluminium mean level was 52.0 micrograms/l with the following frequency distribution: 59.2% below 60 micrograms/l, 25.5% between 60 and 100 micrograms, and 15.3% above 100 micrograms/l. The mean serum aluminium level was higher in patients undergoing haemodialysis with aluminium concentration in fluids over 10 micrograms/l. This was true also in patients not receiving aluminium hydroxide. Furthermore, we found higher average serum aluminium in those treated with aluminium hydroxide more than 3 g/day. No relationship was found between serum aluminium and sex, age, dialytic age, parathyroid hormone, and vitamin D treatment. Moreover, the patients with serum aluminium above 100 micrograms/l had higher serum alkaline phosphatase and lower mean cell volume values. Thus, in our haemodialysis population aluminium overloading occurred in spite of low concentration in water and fluid, and it was a result more of fluid pollution (over 10 micrograms/l) than aluminium hydroxide ingestion (over 3 g/day).

Disappearance of aluminic bone disease in a long term asymptomatic dialysis population restricting A1(OH)3 intake: emergence of an idiopathic adynamic bone disease not related to aluminum

In dialysis centers using reverse osmosis-treated water but not restricting A1(OH)3 administration, a high prevalence of histological aluminum bone disease has been reported. To assess whether this is also the case in our center where A1(OH)3 intake has always been restricted and even completely given up after 1980 thanks to high doses of CaCO3, we reviewed 42 bone biopsies performed between 1975 and 1985 in patients dialyzed for a mean duration of 56 months. Seventeen of these patients had been dialyzed before 1978 with softened water moderately contamined by aluminum, 15 had always been dialyzed with reverse osmosis-treated water and 10 had been exclusively treated by hemofiltration. The prevalence of aluminum bone disease in the whole population was 9.5% (4 patients) and consisted only of adynamic bone disease, osteomalacia being totally absent. When the patients dialyzed with aluminum-contaminated water were excluded as well as 1 diabetic patient who had taken A1(OH)3 for 1.5 years the prevalence of aluminum bone disease was null in this population. When the whole population is considered the prevalence of the other types of bone disease was 76% for osteitis fibrosa and 14.5% for a non-aluminic adynamic bone disease (6 cases). These latter cases differed from the osteitis fibrosa group only by a relative hypoparathyroidism not explained by higher plasma concentrations and higher oral cumulative doses of calcium, magnesium and aluminum or by lower plasma concentrations of phosphate and bicarbonate. None had previous parathyroidectomy, one had an unsuccessful transplantation and one was diabetic. Iron overload was excluded by negative Perls staining.(ABSTRACT TRUNCATED AT 250 WORDS)

Decrease of serum triglyceride in normal rat fed with 2000 ppm aluminum diet for 67 days. II. Feeding young and adult rats a sucrose diet with addition of aluminum hydroxide and aluminum potassium sulfate

To confirm the hypotriglyceridemic effect of aluminum (Al), male weanling and adult Wistar rats were fed sucrose diets with the addition of aluminum hydroxide (Al(OH)3) or aluminum potassium sulfate (AlK(SO4)2) for 67 days. As in the foregoing report (C. Sugawara, N. Sugawara, H. Kiyosawa, and H. Miyake, Fundam. Appl. Toxicol. 10, 607-615), no Al-induced anemia or hypophosphatemia was observed and serum Al did not exceed 20 ng/ml. Serum triglyceride (TG) was decreased by aluminum. Serum TG was significantly correlated with the serum nonesterified fatty acid (NEFA) concentration in both the Young groups (R = 0.757, n = 22, p less than 0.01) and the Adult groups (R = 0.727, n = 19, p less than 0.01). Neither serum cholesterol nor phospholipids was affected by Al ingestion. Aluminum caused a decrease in hepatic glycogen in all groups, but the decrease was significant only in Adult groups. Glycerol tri[9,10(n)-3H]oleate was administered by gastric tube into rats fed for 81 days with experimental diets. In all the Al-treated groups serum 3H was significantly greater than in control groups at 3 hr after intubation. At 24 hr after intubation, serum 3H did not differ between Control and Al-treated groups. Total 3H at 24 hr found in serum, liver, and epididymal adipose tissue was not changed significantly by Al feeding. These effects were observed without measurable increase of Al in the serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum metabolism in rats: effects of vitamin D, dihydrotachysterol, 1,25-dihydroxyvitamin D and phosphate binders

In order to study the effects of vitamin D on aluminium balance when different forms of vitamin D and phosphate binders are used simultaneously for therapeutic purposes, 30 Sprague-Dawley weanling rats, weighing 44-66 g, were randomly assigned to 5 groups: (A) control, (B) aluminum hydroxide, (C) dihydrotachysterol at 16 micrograms/kg/day, (D) 1,25-dihydroxyvitamin D at 16 ng/kg/day and (E) vitamin D at 2,000 IU/kg/day. Aluminum hydroxide (60 mg/kg/day) in the feed was provided to all except the control group. The vitamin D or metabolites were fed by stomach tube daily for a period of 10 days. At the end of the study, the mean (+/- SEM) serum aluminum concentration, as determined by flameless atomic absorption spectrophotometry, was 5.0 +/- 2.4 micrograms/l; there were no significant differences in these results between groups. During the last three days of the study, 24-hour urine and stool collections were made with the usual precautions against trace mineral contamination. The means (+/- SEM) of aluminum balances for groups A, B, C, D and E were -388 +/- 261, 1,121 +/- 331; 2,316 +/- 304; 2,387 +/- 245, and 1,968 +/- 337 micrograms/day, respectively. We conclude that at therapeutic doses of aluminum hydroxide and vitamin D or its metabolites, hyperaluminemia was not observed. However, the positive aluminum balances imply retention, and the use of vitamin D, especially its potent metabolites dihydrotachysterol and 1,25-dihydroxyvitamin D, intensified this risk.

Toxicity and aluminium concentration in bone following dietary administration of two sodium aluminium phosphate formulations in rats

The effects of dietary administration of the basic sodium aluminium phosphates, KASAL and KASAL II, were examined in male rats. Aluminium levels in bone were determined in order to estimate the possible aluminium deposition by these compounds. Groups of 25 male Sprague-Dawley rats were fed control diet or diets containing 30,000 ppm KASAL, 7000 or 30,000 ppm KASAL II, or 14,470 ppm aluminium hydroxide for 28 days. The mean daily aluminium doses were calculated to be 5, 141, 67, 288 or 302 mg/kg body weight/day, respectively. Neither form of KASAL induced detectable toxicity. No adverse treatment-related clinical signs were observed. Body weights and food consumptions were similar in treated and control groups. No toxicologically significant changes were observed in haematology, clinical chemistry parameters or organ weights. No treatment-related changes were observed at autopsy or in histopathological examination of collected tissues. Femurs collected at autopsy under conditions free of aluminium contamination showed no significant deposition of aluminium after dietary administration of KASAL, KASAL II or aluminium hydroxide. All aluminium values in bone were less than 1 ppm and most values were not quantifiable. Thus, dietary administration of up to 30,000 ppm of either of the basic sodium aluminium phosphate formulations caused neither toxicity nor significant deposition of aluminium in femur.

Phosphate-binding properties and electrolyte content of aluminum hydroxide antacids

The phosphate-binding capacities of 19 liquid and solid aluminum hydroxide gel antacids were determined in vitro under varying pH conditions. The resulting data provide a basis explaining the phosphate-binding characteristics observed when patients are treated with long-term aluminum hydroxide therapy. No antacid, liquid or solid, showed significant binding at pH 1.0. Maximum phosphate binding (expressed as phosphorus; P) was observed at pH 2.0 and 3.0 for most antacids and decreased markedly at alkaline pH. The liquid antacids showed a significantly greater phosphate-binding capacity than did tablets or capsules (p less than 0.01). At pH 2.0, the liquid antacids bound a mean of 22.3 mg P/5 ml. At pH 8.0 binding was reduced to a mean of 7.3 mg P/5 ml. Significant interbrand differences were observed. At pH 2.0, the solid antacids bound a mean of 15.3 mg P/tablet or capsule. At pH 8.0, binding was reduced to a mean of 5.8 mg P/tablet or capsule. Interbrand differences, while substantial, were less than those observed among the liquid antacids. Variations in sodium and potassium content were clinically insignificant for most of the antacids in this study, while the differences in phosphate-binding properties were sufficient to warrant attention in the patient with renal failure.

A comparison between pyridinic and non-pyridinic extraction of allergenic materials

The effect of addition of pyridine in the extracting solvent of allergenic materials was studied in the following substances. Dermatophagoides farinae, Chenopodium album, Parietaria judaica, Phleum pratense, Poa pratensis, and Secale cereale. Pyridinated extracts differed significantly in protein content, isoelectric focusing profile, and allergenic activity from the non-pyridinated extracts. On the other hand, no difference was detected between both extraction systems when their adsorption capacity to aluminium gels was compared.

Antacids for peptic ulcer: do we have anything better?

During recent years several reports have appeared documenting that antacids containing aluminium hydroxide accelerate the healing process of duodenal ulcer. In gastric ulcer, however, only one study has demonstrated an effect clearly superior to that of placebo. Several studies, in both gastric and duodenal ulcer patients, have not been able to demonstrate any significant difference between antacids and H2 blockers with respect to ulcer healing and symptom relief. An important acknowledgement is the fact that the doses of antacids required for ulcer healing are much smaller than first assumed, and that tablet formulations of antacids are at least as effective as liquid antacid suspensions. The excellent effect of the more convenient low-dose tablet regimens has strengthened the position of antacids in the competition with other anti-ulcer drugs. Usually, side effects of low-dose antacid regimens are few and mild. In patients with impaired renal function, accumulation of absorbed aluminium may have serious consequences. However, in patients with healthy kidneys, aluminium is quickly excreted after absorption, and unhealthy effects are not documented. Antacids should therefore still constitute a cornerstone in the treatment of peptic ulcers.

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.

Pseudohyperparathyroidism. Syndrome associated with aluminum intoxication in patients with renal failure

Aluminum intoxication is an increasingly frequent complication of chronic renal failure. Because hypercalcemia, elevated parathyroid hormone levels, and radiologic changes said to be typical of osteitis fibrosa commonly occur with aluminum intoxication, it is frequently confused with hyperparathyroidism. In this report, examples of this dilemma are described. The pathophysiology leading to the confusing clinical picture is discussed, with a suggested approach to the problem.

In vitro studies using ion exchange resins as potential phosphate binders for renal failure patients

The uptake of phosphate [expressed as phosphorus (P)] by the anion exchange resins, Dowex 1-X8, Dowex SBR, and Bio-Rex 5, aluminum hydroxide, and sucralfate tablets was evaluated. The maximum uptake capacities (in mg P per gram of "wet" resin or solid) were 56, 49, and 84 mg for Dowex SBR, Dowex 1-X8, and Bio-Rex 5 resins, respectively, and 164-168 mg for aluminum hydroxide and sucralfate. At a concentration of P considered to approximate that encountered in the stomach (0.3 mg/ml), Bio-Rex 5 resin, aluminum hydroxide, and sucralfate bound similar amounts of P. Physiologic concentrations of bicarbonate or chloride and simulated gastric or intestinal fluids caused small changes in P uptake by Bio-Rex 5 resin. The resins bound large quantities of taurocholic (TA) and glycocholic (GA) acids. However, when Bio-Rex 5 was converted to the taurocholate form, it bound the same amount of P as the original chloride-form resin, and the binding of TA was prevented.

Osteoporosis: calcium, fluoride, and aluminum interactions

A gradual loss of bone occurs with age. There are indications in the literature that not only calcium but also fluoride may play an important role in maintaining the bone mass. In view of the high incidence of osteoporosis and its complications, and in view of the fact that fluoride is beneficial for the treatment of osteoporosis, studies have been carried out in this research unit to determine the retention and excretion of fluoride both during a normal dietary intake of fluoride and during fluoride supplementation. Another problem to be examined was to delineate whether certain substances interfere with the intestinal absorption of fluoride and of calcium. One such substance is aluminum contained in commonly used antacids. The use of small amounts of aluminum-containing antacids increased fecal fluoride significantly, thereby decreasing the intestinal absorption of fluoride. In addition, the small doses of aluminum-containing antacids also affected the metabolism of calcium and phosphorus, the primary effect being complexation of phosphorus in the intestine leading to phosphorus depletion. This change in phosphorus metabolism was associated with an increase of the urinary and fecal calcium excretion resulting in a negative calcium balance. The dual effect of aluminum, namely in causing calcium loss and inhibition of the intestinal absorption of fluoride, can result in adverse effects on bone which may contribute to bone loss.