Gijsbert B. van der Voet

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 and release of Al into the blood increased at increasing perfusate concentrations. 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 (μmol l−1) than the mucosal retention (mmol l−1). It is concluded that the intestinal absorption of Al is pH‐ and concentration‐dependent.

The effect of di- and trivalent iron on the intestinal absorption of aluminum in rats

The effect of iron (Fe) on the intestinal absorption of aluminum (A1) was studied in an in situ perfusion system of rat small intestine in combination with systemic and portal blood sampling. The gut was perfused with media containing 0.0, 10.0, 15.0, 20.0, and 25.0 mmol/liter Al chloride and 5 mmol/liter Fe(II) or Fe(III) chloride at pH 3.0. Neither luminal disappearance nor intestinal absorption of A1 were affected by Fe(III). Fe(II), however, enhanced luminal disappearance and reduced absorption of Al.

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.

A method of studying the intestinal absorption of aluminium in the rat

Aluminium (Al) intoxication in dialysis patients is held to be caused not only by Al in the dialysis fluid but also by Al from orally administered phosphate binders. Studies on Al absorption in patients and healthy individuals as well as in animals are still scarce, and do not provide sufficient data to characterize the absorption process.This paper presents a method of studying the process of Al absorption in a perfusion system of rat small intestine in vivo, in combination with a cannulation system of the portal vein for serial blood sampling. Determination of concentrations of an absorbed substance in samples of both the perfusion medium and the portal blood, collected during the perfusion period, may clarify the nature of the absorption process. Although this method appears to be useful for the study of the intestinal absorption of any substance, it was adapted for the study of the intestinal absorption of Al compounds.The usefulness of this method for studying Al absorption was demonstrated in an experiment in which Al chloride (0.5 g/l) in buffered media of pH 7.0, 7.5, and 8.0 was perfused through the rat small intestine over a period of at least 30 min. The results of this experiment indicate that a decrease in pH of the perfusion medium leads to an increase in absorption of Al in the portal blood.

Analysis of bismuth in serum and blood by electrothermal atomic absorption spectrometry using platinum as matrix modifier

Bismuth-containing medicines have been used for years, but there is a lack of clinically applicable methods for measuring bismuth in body fluids. We describe a sensitive, accurate and precise method for analysis of bismuth in blood and serum, which is suitable both for monitoring purposes and for further investigations into the biokinetics and safety of bismuth. Bismuth was quantitated with electrothermal atomic absorption spectrometry with Zeeman background correction. In the furnace programme a cool-down step was introduced and platinum was used as a matrix modifier. Recovery for 40 micrograms/l is 93.7 +/- 4.6% (mean +/- SD) from serum and 92.8 +/- 5.4% from blood; within-day precision (n = 10) at 40 micrograms/l is 3.2% for serum and 4.2% for blood. Day-to-day precision at 40 micrograms/l (n = 10) was 4.5% for serum and 4.0% for blood. The detection limit is 0.7 microgram/l for serum and 1.0 microgram/l for blood. Blood samples have to be collected in glass tubes and stored at -20 degrees C.

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

AbstractThe intestinal absorption of aluminium (Al) from the antacid hydrotalcite (UltacitR) was compared with that from algeldrate (Algeldratum des-acidans) in 8 healthy human subjects in a crossover 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.

Biological monitoring of aluminium in renal patients

Abstract During the past decade, aluminium (Al) has been shown to possess a potential for systemic toxicity. Renal patients form a high-risk group for Al poisoning, and biological monitoring is indicated to diagnose and prevent toxicity. Electrothermal atomic absorption spectrometry is the analytical method of choice for measuring Al levels. Special precautions have to be taken to prevent contamination with environmental Al or adsorption of Al to glassware during analysis. Since this metal is almost evenly distributed between plasma and erythrocytes, either plasma or whole blood may be used to estimate exposure to Al. Measurement in dialysis fluid is suitable to assess parenteral uptake. Hair analysis is of no value. The normal value in plasma is 7.3 ± 2.0 μ g/l ( mean ± SD , n = 10 ); toxic symptoms are mainly associated with levels above 100 μg/l. A dialysate level not exceeding 5 μg/l may be considered safe; intestinal absorption is then the only remaining, highly variable source of Al uptake.

Comparison of enhanced elimination of bismuth in humans after treatment with meso-2,3-dimercaptosuccinic acid and D,L-2,3-dimercaptopropane-1-sulfonic acid

Two groups of 12 human volunteers, who had been treated with colloidal bismuth subcitrate, because of Helicobacter pylori-associated gastritis, participated in the study. The patients received a single dose of meso-2,3-dimercaptosuccinic acid (DMSA) or D,L-2,3-dimercaptopropane-1-sulfonic acid (DMPS) at a dose of 30 mg kg-1 in a randomized single blind study. In contrast to DMPS, increasing concentrations of bismuth in blood were observed during the first 4 h after intake of DMSA. In urine, both chelators induced a 50-fold increase in urinary bismuth excretion compared with the control urines. The treatment was well tolerated. The results indicate that both DMSA and DMPS effectively increase the elimination of bismuth in human urine. Consequently, both chelators may be of benefit in the treatment of patients with bismuth intoxication.

Aluminum affects interconnections between aggregates of cultured hippocampal neurons. Neurotoxicity of aluminum in vitro

The effect of aluminum (Al) was studied in an in vitro system of cultured hippocampal neurons from fetal rats in a chemically defined medium. Neuronal aggregates interconnected by neurites were detected light and electron microscopically in control and Al-treated cultures. In the Al-treated cultures disruptions of the fibers were observed proximal to the aggregates; the number of disruptions increased with The Al concentration applied. It is concluded that interference of intracellular Al with the neuronal skeleton occurs, leading to an enhanced fragility of the interconnecting neurites. The concentration-dependent Al-induced disruption of interconnecting neurites may serve as an in vitro model for further research in Al neurotoxicity.