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[Effect of aluminum on the non-enzymatic oxidation of dopamine].

The effect of different concentrations of aluminum sulphate on the nonenzymatic oxidation of dopamine was studied in order to evaluate the action of this metal on neuromelanin synthesis. Data shows that under the studied conditions, aluminum partially inhibits dopamine self-oxidation, decreasing the formation of some intermediate compounds, namely dopaminequinone and dopaminochrome. If neuromelanins have a cytoprotective function in the central nervous system, possibly acting as intracellular scavengers of free radicals and redox metal ions, their decrease due to aluminum could be responsible for serious damage to neuronal tissues.

Alum Compounds↗

Inhibition of polymerization of polyvinyl siloxanes by medicaments used on gingival retraction cords.

Inhibition of polymerization of polyvinyl siloxane materials by latex products is well documented. It is thought to be caused by contamination of the chloroplatinic acid catalyst by sulfur compounds. Many medicaments, such as aluminum sulfate and ferric sulfate, used on gingival retraction cords have been accused of causing inhibition of set of polyvinyl siloxane materials. Several of these medicaments were tested with two polyvinyl siloxanes and found not to cause any inhibition of set.

Alum Compounds↗

Removal of pharmaceuticals in drinking water treatment: effect of chemical coagulation.

The removal of selected pharmaceuticals (diclofenac, ibuprofen, bezafibrate, carbamazepine and sulfamethoxazole) by chemical coagulation was studied. Jar test experiments were done in MilliQ water, in lake water and in commercial humic acid solutions using aluminium (pH 6) and ferric sulphate (pH 4.5). The concentrations of the pharmaceuticals in the studied water samples were determined by HPLC analysis and UV detection. In MilliQ water coagulation, the pharmaceuticals were poorly removed (< 10%) with the exception of diclofenac, which was removed up to 66% with ferric sulphate. This compound was also the only pharmaceutical removed (30%) during the lake water coagulation with ferric sulphate. In the presence of dissolved humic matter, diclofenac as well as ibuprofen and bezafibrate could be removed by ferric sulphate coagulation. The removal of diclofenac reached a maximum of 77%, while 50% of ibuprofen and 36% of bezafibrate were removed. Hence, a high amount of high-molecular-weight dissolved organic matter enhanced the removal of ionisable pharmaceuticals. The non-ionisable compounds, carbamazepine and sulfamethoxazole, were not affected by the coagulation processes studied. Although conditions such as high humic material content, low coagulation pH and ferric coagulant increase the removal of certain ionic pharmaceuticals, it can be concluded that by coagulation it is not possible to entirely remove pharmaceuticals from water.

Alum Compounds↗

Removal of PCR inhibitors from soil DNA by chemical flocculation.

Extracting high-purity DNA directly from soil has become essential for the study of microorganisms in environmental samples. However, many soils contain compounds that inhibit enzymes involved in manipulating DNA. In this study, chemical flocculation using multivalent cations was investigated as a potential method for eliminating soil-based inhibitors during the extraction process. The addition of AlNH(4)(SO(4))(2) during extraction significantly reduced the co-purification of PCR inhibitors with minimal loss of DNA yield.

Alum Compounds↗

Evaluation of accelerated dechlorination of p,p'-DDT in acidic paddy soil.

The reductive dechlorination and behavior of p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) was investigated in a paddy soil. Treatment with 5% (w/w) metallic iron (Fe(0)) resulted in sharp decrease of p,p'-DDT, whereas there was no extra effect when 2% (w/w) aluminum sulfate (Al(2)(SO(4))(3)) was added to the Fe(0) treatment. These results suggest that Fe(0) could effectively promote the reductive dechlorination of p,p'-DDT and its metabolites while Al(2)(SO(4))(3) did not show any effect on those processes. Furthermore, p,p'-DDT and its daughter compounds inhibited holistic soil respiration greatly at first but could be metabolized by certain species of indigenous microorganisms after a period of adaptation time in the soil. When treated with Fe(0), the polluted soil produced much less CO(2) while the addition of Al(2)(SO(4))(3) counteracted its negative effect to much extent.

Agriculture↗

Comparison of the effiency of aluminium and ferric sulphate in the removal of natural organic matter during drinking water treatment process.

The removal of natural organic matter by coagulation in the drinking water treatment train was studied for a period of two years. In the middle of the study, the coagulation/flotation process was modified by replacing the aluminium sulphate by ferric sulphate. At the same time, the filtration unit was enhanced by adding a sand filter unit before the activated carbon filtration and by changing new carbons on to the activated carbon filters. A special aim was to compare the efficiency of the aluminium and ferric coagulants in the organic matter removal by several methods, including high-performance size-exclusion chromatography. A comparison of quantity and characteristics of organic matter in treated water before and after treatment process modification provided an insight into process performance. Approximately 95% of high molar mass organic substances were removed in the process with both coagulation agents. The greatest difference between the coagulants occurred in the removal of organic matter having molar masses of 1000-4000 g mol(-1). These intermediate molar mass organic compounds were removed 25% more efficiently with iron-based coagulant than with aluminium-based. Low molar mass material was poorly removed regardless of the coagulant. On average, only 10% of this fraction was removed. According to different measuring techniques used in the study, the ferric sulphate coagulation was 10% more efficient in the overall organic matter removal compared to the aluminium sulphate coagulation. Turbidity removal was more efficient with aluminium than with ferric sulphate. Turbidity even increased during winter in ferric sulphate coagulation. However, turbidity was effectively removed in filtrations.

Alum Compounds↗

Aluminum salts stimulate luminol-enhanced chemiluminescence production by human neutrophils.

Aluminum intoxication is currently thought to play a major role in the development of Alzheimer's disease and in certain pathologic manifestations seen during long-term hemodialysis and aging. The hypothesis that aluminum toxicity is mediated via an increased free radical production was tested by studying the effects of two aluminum and five other metallic compounds on the production of luminol-enhanced chemiluminescence (LECL) by human neutrophils. AlCl3, Al2(SO4)3 and FeCl3 were found to stimulate LECL production by human neutrophils whereas FeCl2, CuCl, CuCl2, AuCl3 were inactive. Metal chelators such as Desferal, EDTA and DETAPA suppressed aluminum-induced stimulation and depressed cell-dependent LECL below basal levels. Sodium azide and Cytochalasin B greatly depressed both basal and aluminum-induced stimulation of LECL production, suggesting that, in this system, most of this stimulation was due to myeloperoxidase. These results suggest that high tissue aluminum concentrations may induce cell-tissue lesions by stimulating local production or release of mediators of tissue damage.

Alum Compounds↗

The stabilization of ferrous iron by a toxic beta-amyloid fragment and by an aluminum salt.

Aluminum is a recognized neurotoxin in dialysis encephalopathy and may also be implicated in the etiology of neurodegenerative disease, particularly Alzheimer's disease. Alzheimer's disease is suspected to be associated with oxidative stress, possibly due to the pro-oxidant properties of beta-amyloid present in the senile plaques. The underlying mechanism by which this occurs is not well understood although interactions between amyloid and iron have been proposed. The presence of low molecular weight iron compounds can stimulate free radical production in the brain. This study provides a possible explanation whereby both aluminum and beta-amyloid can potentiate free radical formation by stabilizing iron in its more damaging ferrous (Fe2+) form which can promote the Fenton reaction. The velocity, at which Fe2+ is spontaneously oxidized to Fe3+ at 37 degrees C in 20 mM Bis-Tris buffer at pH 5.8, was significantly slowed in the presence of aluminum salts. A parallel effect of prolongation of stability of soluble ferrous ion, was found in the presence of beta-amyloid fragment (25-35). Ascorbic acid, known to potentiate the pro-oxidant properties of iron, was also capable of markedly stabilizing ferrous ions.

Alum Compounds↗

Separation of Alcaligenes eutrophus cells containing Poly(3-hydroxybutyrate) from fermentation broth with pretreatment using Al- and Fe-based coagulants.

Alcaligenes eutrophus containing intracellular poly(3-hydroxybutyrate) was recovered from fermentation broth by centrifugation and filtration after pretreatment with Al- and Fe-based coagulants. Coagulation efficiency was largely affected by pH, and the optimum pH's for cell recovery were about 4.6-5.6 for the Al-based coagulants and about 5-8 for the Fe-based coagulants. Ammonium ions that combined with metals to form complex compounds increased the coagulant requirement, and the additional requirement of coagulant was found to be proportional to the ammonium concentration. In addition, various ligands in addition to ammonium ions contained in the culture medium interfered with the coagulation reaction and increased the coagulant requirement also. The coagulant requirement increased with the cell concentration regardless of coagulant type. The polymeric coagulants such as PACS, Hi-PAX, and Ferix-3 were more effective than nonpolymeric coagulants of aluminum sulfate and ferrous sulfate. The optimum dosages of the coagulants tested were determined over a broad range of cell concentration of 20.5-210 g/L. It was observed that the energy requirement for centrifugation could be greatly reduced with cell coagulation.

Alcaligenes↗

Aluminium compounds for use in vaccines.

Aluminium adjuvants are the most widely used adjuvants in both human and veterinary vaccines. These adjuvants have been used in practical vaccination for more than 60 years and are generally recognized as safe and as stimulators of Th2 immunity. The present review gives a short introduction to the pioneering research at the start of the use of aluminium compounds as adjuvants, including references on the chemistry of these compounds. Analytical methods for identifying the most commonly used aluminium compounds, such as boehmite and aluminium hydroxyphosphate, are mentioned. Emphasis is placed on the important factors for antigen adsorption and on the latest work using gene-deficient mice in the research of the mechanism of aluminium adjuvants in terms of cytokine and T-cell subset stimulation. Key references on the ability of aluminium adjuvants to stimulate IgE and also in vivo clearing of aluminium adjuvants are discussed. Furthermore, the review addresses the issue of local reactions in the context of injection route and local tissue disturbance. Possible new applications of aluminium adjuvants in, for example, combined aluminium-adsorbed protein and DNA oligonucleotide vaccines as well as the possible use of aluminium adjuvants in combination with IL-12 to stimulate Th1-type immune responses are mentioned.

Adjuvants, Immunologic↗

Protection against alcohol-induced gastric mucosal injury by aluminum-containing compounds--sucralfate, antacids, and aluminum sulfate.

Previously, we demonstrated that both antacids and sucralfate can protect the gastric mucosa against alcohol injury. Since these compounds contain aluminum, we studied whether other aluminum compounds have cytoprotective properties as well. Fasted rats were pretreated intragastrically with A) 0.9% NaCl, B) sucralfate, C) aluminum-magnesium antacid gel, D) Al2(SO4)3, E) Al(OH)3, and 1 h later they received 2 ml 100% ethanol by gavage. The stomach was removed and assessed for injury 3 h after ethanol administration. Control (group A) rats had 39 +/- 3% gross mucosal injury, which was reduced to 5 +/- 1% with sucralfate, 7 +/- 1% with Al2(SO4)3, 12 +/- 2% with Al(OH)3, and 16 +/- 2% with aluminum-magnesium antacid gel pretreatment. Microscopic surface epithelial injury and submucosal edema were seen in all five groups, while deep mucosal necrosis was largely prevented by pretreatment in groups B to E. These findings indicate that aluminum in a wide variety of molecular forms can protect the gastric mucosa against alcohol injury.

Alum Compounds↗

Determination of the effect of aluminium sulphate on natural microbial coenoses in experiment.

The methods of determining the effect of chemical compounds on the processes of microbial self-cleaning of waters are mainly based on the calculation of the number of indicator microorganisms grown after being incubated on complex nutrient media following exposure of the waters with the substances under study. These methods examine the reaction of specific microorganisms under conditions rather different from those really existing in the water reservoir. The author proposes to use the method of heterotrophic assimilation of CO2 for the determination of the activity of natural bacterial associations in the study of the effect on them of both multicomponent sewage waters of industrial plants and specific chemical compounds. The determination of the values of bacterial productivity according to heterotrophic assimilation of CO2 by natural microbial coenosis was used as the criterion of the effect of the toxicant. Toxicity of the substance under study is evaluated according to its inhibitory effect on the production of natural bacteriocoenosis (test object). Field of application: water toxicology, supervision of toxicity of aqueous media, evaluation of the quality of water. Standard experiment examining the effect of aluminium sulphate on natural bacterial coenosis is considered an example. It has been demonstrated that the effect of aluminium sulphate begins to be felt in concentrations starting from 1 mg X l-1. Statistical analysis of results was carried out by calculating the mean value and confidence intervals. The investigations have shown that application of the method of heterotrophic assimilation of CO2 for these purposes is feasible and of considerable interest with a view to its high sensitivity and precision.

Alum Compounds↗

Acute toxicity studies of aluminium compounds: antidotal efficacy of several chelating agents.

Four aluminum compounds--nitrate, chloride, sulphate and bromide--were administered orally and intraperitoneally to rats and mice. The LD50-values (14 days) were determined. The majority of deaths occurring during the first four days. The clinical and physical signs appearing after intoxication include among other lethargy, decreased locomotor activity, piloerection, weight loss and perorbital bleeding. After 14 days no alterations in liver and renal functions were detected in the animals which received intraperitoneally the LD50-values of aluminum nitrate as a single dose. Aluminum concentrations were highest in liver and spleen. No histopathological lesions could be observed. To compare the efficacies of nine chelating agents on the toxicity of aluminum in mice, the therapeutic index and the therapeutic effectiveness of each chelating agent have been calculated. Malic, succinic, oxalic and malonic acids showed the best results with malic and succinic acids being the most effective. Deferoxamine mesylate (DFOA), sodium salicylate, L-cysteine and citric acid were not so effective as antidotes for acute aluminum toxicity. Aurin tricarboxylic acid (ATCA) should not be used due to its high toxicity.

Alum Compounds↗

Bioavailability and intestinal absorption of aluminum in rats: effects of aluminum compounds and some dietary constituents.

In the present investigation, the deposition of aluminum in intestinal fragment and the appearance in blood were studied in a perfused rat intestine in situ for 1 h with several aluminum forms (16 mM). We observed that aluminum absorption was positively correlated with the theoretic affinity of aluminum and the functional groups of the chelating agent. The absorption of aluminum after ingestion of organic compounds is more important than after ingestion of mineral compounds, with the following order: Al citrate > Al tartrate, Al gluconate, Al lactate > Al glutamate, Al chloride, Al sulfate, Al nitrate. Absorption depends on the nature of the ligands associated with the Al3+ ion in the gastrointestinal fluid. The higher the aluminum retention in intestinal fragment, the lower the absorption and appearance in blood. However, the higher aluminum concentration is always in the jejunal fragment because of the influence of pH variation on this fragment. Another objective of the present study was to determine the influence of several parameters on aluminum citrate absorption: with or without 0.1 mmol dinitrophenol/L, with aluminum concentration from 3.2, 16, 32, and 48, to 64 mmol/L, media containing 0, 3, or 6 mmol Ca/L, with or without phosphorus or glucose. It is concluded that aluminum is absorbed from the gastrointestinal tract by (1) a paracellular energy independent and nonsaturable route, mainly used for high aluminum concentration, which is modified by extracellular calcium, and (2) a transcellular and saturable route, the aluminum level was not modified with enhancement of aluminum quantity in intestinal lumen. This pathway can be similar with calcium transfer through the intestine and is energy dependent because of a decrease of aluminum absorption that follows the removal of glucose and phosphorus.

Alum Compounds↗

Use of zeolitised coal fly ash for landfill leachate treatment: a pilot plant study.

Treatment of municipal solid waste (MSW) landfill leachate generally results in low percentages of nutrient removal due to the high concentration and accumulation of refractory compounds. For this reason, individual physical, chemical and biological processes have been used for the treatment of raw landfill leachate and sometimes for the mixture of domestic wastewater and landfill leachate. In this work, the possibility of treating landfill leachate was tested in a bench-scale pilot plant by a two-step method combining adsorption and coagulation-flocculation. Zeolite synthesized from coal fly ash, a by-product of coal-fired power stations, was used in this study both as a decantation aid reagent and as an adsorbent of COD and NH4-N. The coagulation-flocculation step was performed by the use of aluminium sulphate and a polyelectrolyte (ACTIPOL A-401). The leachate was collected directly from a storage unit of the organic fraction of MSW, before it was composted. For this reason the raw leachate was diluted before treatment. The sludge was recirculated to enhance the removal efficiency of nutrients as well as to optimize flocculant saving and to decrease sludge production. The results showed that it is possible to remove 43%, 53% and 82% of COD, NH4-N, and suspended solids, respectively. Therefore, this method may be an alternative for ammonium removal, as well as a suitable pre- or post-treatment step, in combination with other processes in order to meet regulatory limits.

Alum Compounds↗

Oxidation mechanism of As(III) in the UV/TiO2 system: evidence for a direct hole oxidation mechanism.

Although it is well-known that As(III) is oxidized to As(V) in the UV/TiO2 system, the main oxidant for that reaction is still not clear. Accordingly, the present study aims at reinvestigating the TiO2-photocatalyzed oxidation mechanism of As(III). We performed a series of As(II) oxidation experiments by using UV-C/H2O2 and UV-A/TiO2, focusing on the effects of competing compounds. The experiment with UV-C/H2O2 indicated that HO2*/O2-* is not an effective oxidant of As(III) in the homogeneous phase. The effects of oxalate, formate, and Cu(II) on the photocatalytic oxidation of As(III) contradicted the controversial hypothesis that HO2*/ O2-* is the main oxidant of As(III) in the UV/TiO2 system. The effect of As(III) on the TiO2-photocatalyzed oxidations of benzoate, terephthalate, and formate was also incompatible with the superoxide-based As(II) oxidation mechanism. Instead, the experimental observations implied that OH* and/or the positive hole are largely responsible forthe oxidation of As(III) in the UV/TiO2 system. To determine which species plays a more significant role, the effects of methanol and iodide were tested. Since excess methanol did not retard the oxidation rate of As(III), OH* seems not to be the main oxidant. Therefore, the best rationale regarding the oxidation mechanism of As(III) in the UV/TiO2 system seems to be the direct electron transfer between As(III) and positive holes. Only with this mechanism, it was possible to explain the data of this study. Besides the mechanistic aspect, an application method for this technology was sought. The usage of UV/TiO2 for oxidizing As(II) requires a posttreatment in which both As(V) and TiO2 should be removed from water. For this objective, we applied FeCl3 and AIK(SO4)2 as coagulants, and the result implied that the combined usage of TiO2 and coagulation might be a feasible solution to treat arsenic contamination around the world.

Adsorption↗

Chronic toxicity and tumorigenicity study of aluminum potassium sulfate in B6C3F1 mice.

The tumorigenic potential of aluminum potassium sulfate [A1K (SO4)2 12H2O, APS], a compound which exists widely in the environment, was investigated in B6C3F1 mice. APS was administered in the diet for 20 months at dose levels of 1.0, 2.5, 5.0 and 10.0% (w/w). One group receiving the basal diet served as the control. Body weight gain in both sexes was decreased in the 10.0% APS treated group, and increased in the 1.0 and 2.5% APS treated groups. The survival rates at the end of the dosing period were 73.3% (male) and 78.3% (female) in the control group, and 86.7-95.0% (male) and 86.7-91.7% (female) in the APS treated groups. The survival rate showed a tendency to increase in both sexes in all the APS treated groups. In the tumor pathology, the incidence of hepatocellular carcinoma was significantly decreased in the males in the 10% APS treated group. The incidence of hepatocellular carcinoma was significantly decreased in females in all groups including the control group. As regards the nontumorous pathology, the incidence of myocardial eosinophilic cytoplasm showed a significant dose-dependent decrease in males in the APS treated groups. A comparison between the sexes revealed a significant decrease in the incidence of hepatocytic anisonucleosis, myocardial eosinophilic cytoplasm and acinar cell vacuolation of the submandibular gland in the females; and lymphocyte infiltration in renal cortex and pelvis, and vacuolation of cerebellar white matter were noted in the males. The results of the present study indicate that long-term administration of APS does not exert tumorigenic or any other toxic actions in B6C3F1 mice.

Alum Compounds↗