Allergy to nickel in dental alloys.

A case of oral allergy to dental alloys is presented, highlighting the interest of dosage of salivary nickel and of flow cytometry showing a selective CD4+ activation. The discrepancy between the rarity of oral allergy to dental alloys and the frequency of nickel sensitization and nickel-induced contact dermatitis leads to discuss the mechanisms of oral tolerance.

In vitro and in vivo studies on chelation of manganese.

This work deals with new chelating agents of manganese (Mn). Out of 24 compounds chosen for their chemical structure supposed to be favorable for Mn complexation, six polyaminopolycarboxylic acids proved to be efficient for displacing Mn bound to serum bovine proteins in vitro: TTHA, DTPA, DPTA, DPTA-OH, HBED, EDTA (mobilization > or =50%). The first five compounds were then tested in vivo on rats pretreated with MnCl2. They exhibited only slight to moderate efficacy to diminish Mn in tissues and were ineffective on increased Mn concentration in whole blood; in addition, they had different and specific mobilizing effects on other essential elements (Fe, Zn, Cu). Their limited efficacy in vivo could be due to the formation of very stable complexes between Mn2+ and different molecules such as hemoglobin and certain cytochromes, instead of Fe2+. This could disturb the functioning of the cellular respiratory chain, leading to an incomplete reduction of O2 with formation of free oxygenated radicals, reduction in the energy supply, and disturbance of the cytochromes renewal mechanism. All of these phenomena could accelerate cellular aging and explain the lack of efficacy of the chelating agents towards Mn neurotoxicity (Parkinson's syndrome).

Nickel absorption and distribution from rat small intestine in situ.

The aim of this work was to study the absorption of nickel chloride in rats by means of the intestinal perfusion in situ technique at nickel concentrations of 1, 5, 10, 25, and 100 mg/L. Active transport and facilitated diffusion seem to play an important role in the intestinal absorption of nickel at concentrations < or = 10 mg/L. At higher concentrations, the absorption rate would be limited by saturation of the carriers. The distribution of the absorbed nickel was studied by intestinal perfusion of a 10-mg Ni/L solution for 30 or 60 min. Both in concentration and amount, the jejunum showed the higher values of absorbed nickel, followed by the kidneys and liver. When all of the collected organs (brain, heart, liver, lungs, spleen, kidneys, and testicles) and blood, but not the small intestine, are analyzed following a 60-min perfusion, it was found that 1% of the initial concentration had passed through the intestinal barrier.

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.

The effects of aluminum, iron, chromium, and yttrium on rat intestinal smooth muscle in vitro.

The modification of peristaltic activity in the presence of several metal ions has been investigated in the rat intestine by the isolated organ technique. The metals tested modify the intestinal movements: aluminum, chromium, and yttrium cause a decrease of amplitude, while iron showed no effect. By use of microscopic techniques, the presence of yttrium hydroxide was observed in the intestinal tissues. Iron also appears as a precipitate outside of the intestinal serosal, which may explain why iron did not modify the peristaltism. Chromium and aluminum were not apparent to microscope, despite being detected and quantified in the tissues by means of atomic emission spectrometer. We conclude that the trivalent ions of these elements may operate differently on the mechanisms of intestinal contractions: yttrium precipitates in intercellular spaces, iron precipitates outside the intestines, and chromium and aluminum remain in solution and are distributed homogeneously in the smooth intestinal muscle.

Effect of aluminum on superoxide dismutase activity in the adult rat brain.

Male rats were treated daily with an intraperitoneal injection of 15 mg aluminum (Al chloride)/kg body weight for 17 d, in order to study the effects on superoxide dismutase (SOD) activities in the brain (cortex). No significant difference between control and treated animals was registered in the Cu/Zn and Mn SOD activities in the gray matter of the cortex. High Al levels were found in the plasma, the spleen, and the liver of the treated animals in comparison to the controls, but not in the cortex homogenates (gray matter). In addition, Al induced a significant decrease in food ingestion and weight gain.

The genotoxicity of iron and chromium in electroplating effluents.

Electroplating effluents were tested for their genotoxicity with the micronucleus test on newt larvae. The metallic content of the tested samples was responsible for the induction of micronuclei in red blood cells (RBC). Then, iron (Fe3+), chromium (Cr3+, Cr6+) and zinc (Zn2+) which were identified in these samples, were tested either separately or combined, at their concentrations in the electroplating effluents. Fe3+ induced a high level of micronuclei at 12.5 and 25 mg/l (nominal concentrations). Both soluble and non-soluble forms of iron were responsible for these genotoxic effects. At lower concentrations (0.6 and 4.5 mg/l) Fe3+ was not systematically genotoxic. Zinc could not be considered genotoxic on newt. Cr3+ gave negative responses, but exposure to Cr6+ (1 mg/l) could result in a significant number of micronucleated RBC in some cases. The most dramatic genotoxic effects were registered when Fe3+ and Cr6+ were combined. This study demonstrates that interactions between pollutants and the effects of non-soluble chemicals on aquatic vertebrates and invertebrates can no longer be neglected.

Effects of aluminum chloride on normal and uremic adult male rats. Tissue distribution, brain choline acetyltransferase activity, and some biological variables.

Normal and uremic adult male rats were given a daily ip injection of 20 mg Al (Al chloride)/kg for 14 d. The results indicate that Al induces a significant decrease in food ingestion, weight gain, and total protein concentration in the plasma. Compared with control animals, very high increases in Al levels were found in plasma and hepatic homogenates (about 36 and 19 times, respectively). In the brain homogenates, the Al increases were lower (about 23%). The brain cholineacetyltransferase activity was reduced: 10.6 and 14.9% in normal and uremic rats, respectively. The nephrectomy and the food restriction did not affect the total protein concentrations in plasma and the cerebral cholineacetyltransferase activity. Both were only found to be reduced in the rats treated by Al chloride.

Reduction of dietary phosphorus absorption by oral phoshorus binders.

The aim of this study was to study a possible new non-aluminum phosphate-binder to limit hyperphosphatemia in patients with renal failure. Zirconyl chloride octahydrate was evaluated as a dietary phosphate binder in rats. Aluminum chloride hexahydrate was used as a reference. Animals were divided into six groups (6 animals per group): One - control group (C), two - aluminum groups (Al1 and Al2) and three - zirconium groups (Zr1, Zr2 and Zr3) receiving different doses of zirconyl chloride octahydrate. Urines were collected during the experimental period. At the end of the treatment, the animals were sacrified and plasma and different organs were collected (liver, spleen, kidneys, brain and femur). Determination of phosphorus and calcium levels in plasma indicated that zirconyl chloride octahydrate yielded as good results as aluminum chloride hexahydrate did. Zirconyl chloride octahydrate significantly (p<0.01) reduced bone phosphorus burden. Urinary excretion of phosphorus indicated a severe phosphorus depletion in all treatments. Not even traces of zirconium could be determined in the different tissues, in urines or in plasma. Consequently, it is important to carry out experiments with zirconium compounds in order to develop non-aluminum-containing phosphate binders.

In vitro and in vivo evaluation of potential aluminum chelators.

The potential for aluminium (Al) chelation by different compounds was determined using 2 in vitro techniques. The formation of stable complexes with Al in an aqueous solution was evaluated using pulse polarography. This technique allowed the influence of temperature and calcium (Ca) to be studied for each compound. Certain compounds (EDDHA, HAES, citric acid and HBED) showed great chelation in the absence of Ca2+ at a temperature of 37 +/- 1 C. An ultrafiltration technique combined with Al determination by atomic emission spectroscopy allowed the efficiency of different substances to complex Al that were previously bound to serum proteins to be estimated. The kinetics of chelation and minimum efficient concentration have been determined for all products studied. EDDHA had chelation potential similar to DFO. The real efficacies of the compounds were studied in vivo to compare the effectiveness of repeated administrations of the best chelating agents (EDDHA, DFO, HAES and tartaric acid) on the distribution and excretion of Al after repeated i.p. administrations to rats. Intraperitoneal EDDHA significantly increased urinary metal (Al, Ca, Cu, Fe and Zn) excretion. These excretions may be correlated to a renal toxic potential property.

A possible non-aluminum oral phosphate binder? A comparative study on dietary phosphorus absorption.

The aim of this study was to highlight a possible new non-aluminum phosphate-binder to limit hyperphosphatemia in patients with renal failure. Lanthanum chloride hydrate was evaluated as a dietary phosphate binder in rats. Aluminum chloride hexahydrate was evaluated as a reference. Animals were divided in five groups (6 animals per group): 1 control group (C), 2 aluminum groups (Al1 and Al2), receiving different doses of aluminum chloride hexahydrate and 2 lanthanum groups (La1 and La2), receiving different doses of lanthanum chloride hydrate. During the treatment, urine and stools were collected. At the end of the treatment animals were sacrificed and plasma and different organs were collected (liver, spleen, kidneys, brain and femur). To highlight the possible transfer of lanthanum in rat tissues, a long-term (100 days) study was carried with a high dose. At the end of the treatment, lanthanum determinations were carried out on several tissues (liver, spleen, kidneys, brain, femur and lungs). Determinations of phosphorus and calcium levels in plasma indicated that lanthanum chloride hydrate showed as good results as aluminum chloride hexahydrate. Lanthanum chloride hydrate significantly (p < 0.01) reduced the bone phosphorus burden. Decreases of urinary excretion and increases in fecal excretion of phosphorus indicated a severe phosphorus depletion in all treatments (Al and La). Unfortunately, in the long-term study, lanthanum traces could only be determined in the different tissues but not in plasma. However, in comparison with the equivalent aluminum treatment, the transfer of lanthanum was less important than aluminum transfer. Consequently, lanthanum could provide a possible alternative to aluminum.

Effects of postnatal aluminum exposure on biological parameters in the rat plasma.

Young rats were treated by gastric intubation with aluminum chloride (100 mg Al/kg/day) and aluminum lactate (100 and 200 mg Al/kg/day) from postnatal days 5 to 14. This treatment lead to a reduction in body weight. The plasma concentrations of total proteins and albumin decreased whereas the alpha 1 globulins increased in the treated rats. The aluminum concentrations in plasma and hepatic homogenates increased particularly at 200 mg Al lactate. The reduction in average body weight could be attributed to various causes: a decreased food consumption, a transient undernutrition, a reduction of the protein synthesis in the liver. The increase of the plasma concentration of the alpha 1 globulins revealed an inflammation process.

In vitro and in vivo comparative studies on chelation of aluminum by some polyaminocarboxylic acids.

Since desferrioxamine exhibits toxic effects, the possible use of several other therapeutic agents in acute aluminum intoxication has been investigated in this study. The potential for the chelation of aluminum (Al) by different compounds has been first determined using two in vitro techniques. The formation of stable complexes with Al in an aqueous solution has been evaluated by using pulse polarography. This technique allows the influence of temperature and of calcium (Ca) to be studied for each compound. Certain compounds (HEDTA, DTPA) showed extensive chelation in the presence of Ca2+ at a temperature of 37 +/- 1 degree C. An ultrafiltration technique combined with Al determination by atomic emission spectroscopy (A.E.S.) has allowed the ability of different substances to complex Al that was previously bound to serum proteins, to be estimated. The kinetics of chelation and the minimum efficient concentration have been determined for all of the products studied. The real efficacies of the compounds were studied by in vivo investigations to compare the effectiveness of the best chelating agents (DFO, HEDTA and EDTA) on the distribution and excretion of Al, after repeated i.p. administration to rats. HEDTA shows a chelation potential as widely active as the DFO potential.

Experimental articular toxicity of aluminum compounds in vivo.

OBJECTIVE: To investigate the articular toxicity of 2 aluminum derivatives, one insoluble (hydroxide) and/or the other soluble (lactate), after a single administration in rabbits and rats. METHODS: First, aluminum levels in plasma, urine, synovial tissue, liver and kidney were measured in saline treated rabbits and 1 to 2 days after an articular injection of 75 mg of aluminum compounds into their right knee. The methodology used was argon plasma emission spectrometry. Thereafter, the joint toxicity of aluminum lactate at the same dose regimen was evaluated for 2 days by a qualitative histological examination of synovial tissue and articular surfaces and a colorimetric assay (1,9-DMB) of patellar articular cartilage proteoglycan content. Secondly, the single injection of 50 mg of aluminum derivatives as an inducer of inflammation was studied in the rat subcutaneous air pouch, a model for a synovial-like space. Leukocytes and eicosanoids levels were measured in pouch washout fluids from 1 to 72 h after injection. RESULTS: After injection into rabbit knee, aluminum lactate largely distributed within the body while hydroxide remained locally. However, aluminum lactate resulted in perivascular edema, sparse infiltration of inflammatory cells in the synovium and a hemorrhagic effusion. Proliferation of the synovial cell layer coexisted with an apparent loss of proteoglycan in superficial zones of tibial and femoral cartilages when patellar proteoglycan content remained unchanged. Aluminum hydroxide did not affect joint structures. In the air pouch experiment, aluminum lactate increased prostaglandin E2 (PGE2) levels from 3 to 10 h after its injection and less intensively leukotriene B4 (LTB4) levels after 6 h, in the absence of leukocytes migration into the cavity. In contrast, aluminum hydroxide increased leukocytes count in pouch-washout fluid from 3 to 24 h after its injection when PGE2 and LTB4 levels were little modified. CONCLUSION: Although some differences attributable to dissimilarities in the experimental model used, aluminum compounds, even in a soluble form, may damage joint structures either directly or through stimulating the secretion of eicosanoids by synovial-like cells.

[Qualitative and quantitative study of bone colonisation in a wired surface effect. An experimental study]. / Evaluation qualitative et quantitative de la colonisation osseuse dans un effet de surface grillagé. Etude expérimentale.

PURPOSE: The aim of this study was to evaluate the bony anchorage of a new implant (orderly wired surface effect with alloy Ti Al Va and ordered pores of 488 mu). Bony integration was analyzed on qualitative and quantitative aspects. MATERIALS AND METHODS: The implants were inserted into both femurs of six sheep in three localisations, in all 36 implants, during a period of 6 to 33 weeks. The implants were opposed on cortical bone or impacted into trabecular cancelous bone after corticotomy. Evaluation of rehabitation was realized using conventional radiography, MRI, isotopic study and particularly by computer assisted histomorphometry (BIOCOM program). This new technic evaluated the trabecular bone volume (TBV) of the implant, the trabecular bone density, and the mean trabecular width in real value with precision and objectivity. RESULTS: This study shows that there was good osteointegration of the implant, that this osteointegration differed with the localization of implantation. Quantitatively, the BIOCOM program showed that for metaphyseal implants in cancelous bone, the TBV of the implant was greater than that of the environment of the implant. DISCUSSION: It is questionable to speak of osteoinduction in an osteogenic situation but it is certain that in many implantation conditions, the TBV is more important in the implant than that of the environment surrounding the implant. This shows the excellent osteointegration of the implant. CONCLUSION: This implant brings a new concept of rehabitation space with its particular geometry of structure. This quality is confirmed by clinical experience with uncemented knee prosthesis.

Element variations in pregnant and nonpregnant female rats orally intoxicated by aluminum lactate.

Pregnant or nonpregnant female rats were orally intoxicated by aluminum lactate (400 mg Al/kg/d) from d 0-19 of gestation to determine the treatment's influence on element variations in the females and their fetuses. The aluminum levels of plasma, liver, spleen, and kidneys were significantly higher in treated pregnant rats than non-pregnant female rats. Differences of P, Ca, Cu, Zn, or Mg levels were observed among the four groups of female rats in the tissues and plasma. The aluminum content of the 20-d-old fetuses did not significantly differ between the treated and control groups. On the contrary, calcium and magnesium levels in the whole fetuses from treated or nontreated dams are significantly different.

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.

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.