Disseminated arterial calcification and enhanced myogenic response are associated with abcc6 deficiency in a mouse model of pseudoxanthoma elasticum.

OBJECTIVE: Pseudoxanthoma elasticum is an inherited metabolic disorder resulting from ABCC6 gene mutations. It is characterized by progressive calcification and fragmentation of elastic fibers in the skin, retina, and the arterial wall. Despite calcium accumulation in the arteries of patients with pseudoxanthoma elasticum, functional consequences remain unknown. In the present study, we investigated arterial structure and function in Abcc6(-/-) mice, a model of the human disease. APPROACH AND RESULTS: Arterial calcium accumulation was evaluated using alizarin red stain and atomic absorption spectrometry. Expression of genes involved in osteochondrogenic differentiation was measured by polymerase chain reaction. Elastic arterial properties were evaluated by carotid echotracking. Vascular reactivity was evaluated using wire and pressure myography and remodeling using histomorphometry. Arterial calcium accumulation was 1.5- to 2-fold higher in Abcc6(-/-) than in wild-type mice. Calcium accumulated locally leading to punctuate pattern. Old Abcc6(-/-) arteries expressed markers of both osteogenic (Runx2, osteopontin) and chondrogenic lineage (Sox9, type II collagen). Abcc6(-/-) arteries displayed slight increase in arterial stiffness and vasoconstrictor tone in vitro tended to be higher in response to phenylephrine and thromboxane A2. Pressure-induced (myogenic) tone was significantly higher in Abcc6(-/-) arteries than in wild type. Arterial blood pressure was not significantly changed in Abcc6(-/-), despite higher variability. CONCLUSIONS: Scattered arterial calcium depositions are probably a result of osteochondrogenic transdifferentiation of vascular cells. Lower elasticity and increased myogenic tone without major changes in agonist-dependent contraction evidenced in aged Abcc6(-/-) mice suggest a reduced control of local blood flow, which in turn may alter vascular homeostasis in the long term.

Concentration of bone elements in osteoporosis.

In aging and in osteoporosis, decreased bone density is associated with decreased bone mass. However, changes in the bone mineral phase remain a matter for investigation. In particular, it is unknown whether bone mineral loss is directly related to reduction in bone mass or associated with changes in the concentration of mineral elements in mineralized bone tissue. In this study, the cortical bone concentration of elements was determined in biopsies of the ilium from 33 subjects (12 controls and 21 individuals with untreated severe osteoporosis). Calcium and phosphorus concentrations were evaluated in cortical and trabecular bone using energy-dispersive x-ray (EDX) microanalysis and inductively coupled plasma optical emission spectrometry (ICPOES). Bone concentrations of Na, K, Mg, Cu, Zn, Fe, Sr, Al, B, and Si were also determined in cortical bone using ICPOES. Additionally, the concentration of F in cortical bone was measured with a specific ion electrode and the concentration of Pb was determined by atomic absorption spectrometry. In mineralized bone tissue there was no significant age-dependent variation in the concentration of Ca, P, or other elements either in controls or in osteoporotic subjects. Moreover, the concentration of elements in bone tissue did not differ in the two groups. These results suggest that the decrease in bone density in osteoporosis is directly related to evolution of the bone mass, without detectable changes in the concentration of elements in bone.

Strontium distribution and interactions with bone mineral in monkey iliac bone after strontium salt (S 12911) administration.

The analysis of the interaction of strontium (Sr) with bone mineral is of interest because a new agent containing Sr (S 12911) has shown positive effects on bone mass in various animal models of osteoporosis and is currently being developed for preventive and curative treatment of postmenopausal osteoporosis. Iliac bone samples were obtained from 20 male monkeys: 4 untreated control animals, 12 animals sacrificed at the end of a 13-week treatment with high dose levels of S 12911 (750, 275, or 100 mg/kg/day orally), and 4 animals sacrificed 6 weeks after the end of a 13-week treatment with S 12911 (750 or 100 mg/kg/day orally). The distribution of Sr was determined and quantified by X-ray microanalysis. Changes at the crystal level were evaluated by X-ray diffraction and Raman microspectrometry. In the control animals, traces of Sr were found to be homogeneously distributed throughout the bone tissue. In the treated monkeys, Sr could only be detected in calcified matrix. In monkeys sacrificed at the end of the treatment, Sr was found to be dose-dependently incorporated into the mineral substance of the compact and cancellous bone. Sr was heterogeneously distributed with three to four times more Sr in new than in old compact bone, and approximately two and a half times more Sr in new than in old cancellous bone. The bone Sr content dramatically decreased in the animals sacrificed 6 weeks after the end of the treatment. Diffraction showed no significant changes in the characteristics of the crystal lattice. Sr appeared to be easily exchangeable from bone mineral and was slightly linked to mature crystals through ionic substitutions. Even at the highest dose level tested, less than 1 calcium ion out of 10 was substituted by 1 Sr ion in each crystal. In conclusion, taken up by bone, Sr was heterogeneously distributed with a higher concentration in new than in old bone but induced no major modifications of the bone mineral (crystallinity, crystal structure) at the crystal level. As a result, a treatment with S 12911 Sr salt should not induce any alteration of bone mineral.

Incorporation and distribution of strontium in bone.

The distribution and incorporation of strontium into bone has been examined in rats, monkeys, and humans after oral administration of strontium (either strontium chloride or strontium ranelate). After repeated administration for a sufficient period of time (at least 4 weeks in rats), strontium incorporation into bone reaches a plateau level. This plateau appears to be lower in females than in males due to a difference in the absorption process. Steady-state plasma strontium levels are reached more rapidly than in bones, and within 10 days in the rat. The strontium levels in bone vary according to the anatomical site. However, strontium levels at different skeletal sites are strongly correlated, and the strontium content of the lumbar vertebra may be estimated from iliac crest bone biopsies in monkeys. The strontium levels in bone also vary according to the bone structure and higher amounts of strontium are found in cancellous bone than in cortical bone. Furthermore, at the crystal level, higher concentrations of strontium are observed in newly formed bone than in old bone. After withdrawal of treatment, the bone strontium content rapidly decreases in monkeys. The relatively high clearance rate of strontium from bone can be explained by the mechanisms of its incorporation. Strontium is mainly incorporated by exchange onto the crystal surface. In new bone, only a few strontium atoms may be incorporated into the crystal by ionic substitution of calcium. After treatment withdrawal, strontium exchanged onto the crystal is rapidly eliminated, which leads to a rapid decrease in total bone strontium levels. In summary, incorporation of strontium into bone, mainly by exchange onto the crystal surface, is dependent on the duration of treatment, dose, gender, and skeletal site. Nevertheless, bone strontium content is highly correlated with plasma strontium levels and, in bone, between the different skeletal sites.

[Microdetermination of lead and cadmium in blood and urine by graphite furnace atomic absorption spectrophotometry (author's transl)]. / Microméthode de dosage du plomb et du cadmium dans le sang et l'urine par absorption atomique au four graphite.

A microtechnique is described for determination of lead and cadmium in blood (0.1 ml) and in urine (0.2 ml) using extraction into methyl isobutyl-ketone after chelation by ammonium pyrrolidine dithiocarbamate. Mineralization, precipitation of proteins or addition of hemolysing reagents are not necessary. Blood is hemolysed by addition of deionised water. pH of urine is fixed by a pH 5 buffer. This microtechnique is simple, rapid, reproducible and suitable for routine analysis. In healthy subjects it gives values comparable to data of other workers: blood 158 microgram/l lead (s = 40, n = 18); 0.7 microgram/l cadmium (s = 0.3, n = 10); urine 16 microgram/l lead (s = 9.4, n = 10); 0.5 microgram/l cadmium (s = 0.3, n = 10).

Blood cadmium concentration in the population of the Rabat area, Morocco.

Blood cadmium concentrations were determined in 377 adults, 297 men and 80 women, randomly selected from the Rabat Transfusion Center, Morocco. The mean blood cadmium level was 1.1+/-0.7 microg/l, which was higher than in French subjects, with an average of 0.7+/-0.6 microg/l. In Moroccan people, the mean blood cadmium concentration of men, 1.1+/-0.8 microg/l, was significantly higher than that of women, 0.8+/-0.4 microg/l, whereas in the French people tested, there was no statistically significant difference between men and women. In Morocco, employment of men and the smoking habits of men and women were linked to an increase of blood cadmium levels. The significantly higher level observed in men could be due to a higher percentage of men who were smokers and to professional activity leading to increased exposure to cadmium.

Increase in blood plasma levels of boron and strontium in hemodialyzed patients.

Boron and strontium concentrations in blood plasma of controls and hemodialyzed patients from two Centers were determined by inductively coupled plasma emission spectrometry. Boron concentrations in blood plasma were respectively, in controls 2.6 +/- 0.9 mumol/l and in hemodialyzed patients 16.1 +/- 5.6 mumol/l before the dialysis session and 9.5 +/- 3.2 mumol/l at the end. The decrease in blood plasma during the dialysis was concomitant with an increase in the dialysis fluid (1.2 +/- 0.7 mumol/l at the beginning and 4.6 +/- 1.8 mumol/l at the end). Strontium concentrations in blood plasma were respectively, in controls 0.22 +/- 0.06 mumol/l and in hemodialyzed patients 0.62 +/- 0.24 mumol/l before the dialysis session and 0.64 +/- 0.14 mumol/l at the end. The mean concentration of strontium in the dialysis fluid was the same before (0.49 +/- 0.11 mumol/l) and after the dialysis session (0.49 +/- 0.10 mumol/l), but a transfer between plasma and dialysis fluid was shown by individual changes. Some considerations about these results are put forward but their possible clinical consequences are not yet known.

Pharmacokinetics of desferrioxamine and of its iron and aluminum chelates in patients on peritoneal dialysis.

We have studied the pharmacokinetics of desferrioxamine (DFA), ferrioxamine (FeA) and aluminoxamine (AlA) in patients with chronic renal failure on continuous ambulatory peritoneal dialysis (CAPD) after 10 mg/kg (15.24 mumol/kg) body weight desferrioxamine (DESFERAL) administration by intramuscular and intraperitoneal routes. The results show an easy exchange of DFA between the plasma and the peritoneal fluid regulated by the relative concentrations of DFA in the two compartments. When the equilibrium is reached, the concentration of DFA are approximately the same in the plasma and the peritoneal fluid.

Pharmacokinetics of desferrioxamine and of its iron and aluminium chelates in patients on haemodialysis.

We have used a new analytical micromethod to study the pharmacokinetics of desferrioxamine and its aluminium chelates in patients with chronic renal failure on haemodialysis. Desferrioxamine (Desferal, CIBA, Basle) was given by 1-h infusion just after the haemodialysis at 20, 40, 80 mg/kg body wt. and during the first and the last hour of the haemodialysis at 40 mg/kg. The concentrations of desferrioxamine during infusions showed a linear increase with increasing doses. The maximum concentrations and the AUC obtained when desferrioxamine was infused during the haemodialysis were not statistically different but slightly lower than those obtained in post dialysis administration. This result indicates that the loss of desferrioxamine by transfer in the dialysate is quite moderate within 1 h. During the interdialysis period, there was a decrease of plasma desferrioxamine concentrations with a mean half-life of 18.7 +/- 5.2 h and an increase in plasma concentrations of aluminium desferrioxamine chelate. In vitro studies show that a lengthy contact between desferrioxamine and plasma is necessary for complete chelation of A1 already present in plasma. During the following dialysis session, there was an important decrease of desferrioxamine and of its iron and aluminium chelates in blood plasma representing their transfer to the dialysis fluid.

Fatal poisoning due to intravasation after oral administration of barium sulfate for contrast radiography.

A fatal poisoning after oral administration of barium sulfate for contrast radiography is reported. Barium sulfate is an insoluble salt and therefore is almost nontoxic. The case described here involves a 61-year-old woman who underwent two CT scans of the digestive tract with oral administration of barium sulfate during a surgical procedure. Within several hours after the first barium swallow examination the patient presented nonspecific neurologic and cardiovascular manifestations that rapidly progressed and led to death a few days later. Laboratory findings demonstrated elevated levels of barium in the blood and cerebrospinal fluid. The most likely mechanism of poisoning was progressive intravasation of barium due to stasis of contrast material related to intestinal obstruction.

Tissue distribution of some elements in rats.

The concentrations of 14 elements were determined in rat whole blood, plasma, brain, heart, skeletal muscle, liver, kidney, spleen, thymus, and bone, using multielement ICP optical emission spectrometry. The tissue to plasma concentration ratios were calculated in order to determine tissue distribution and its homogeneity. The results show the likely sequences of element concentrations in tissues: RB>P≥K>(Fe)>Zn≥Mg>Cu>S>(Sr≥Ca>Na); and of the homogeneity of the distribution: (Fe)

Effects of etretinate on the distribution of elements in rats.

We studied in the rat the effects of the drug etretinate (Tigason), given at three doses 3, 10, and 30 mg/kg body wt for 1 mo, on the concentrations of Na, K, Ca, Mg, Fe, S, P, Cu, and Zn in the plasma, brain, thymus, heart, liver, lung, kidney, testicle, muscle, and bone. The elements were simultaneously determined in tissues after nitric acid dissolution by inductively coupled plasma emission spectrometry using a JY 48 instrument. At the dose of 3 mg/kg, etretinate did not induce any statistically significant modifications of the element distribution. At the dose of 10 mg/kg, the main observed modifications were in plasma an increase of copper (+38%) and a decrease of zinc (-25%). At the highest dose of 30 mg/kg, some variations of the concentrations of elements in tissues were observed. But, on no account did retinoids induce an alteration of the mineral composition of bone, despite obvious macroscopic bone alterations.

Transport measurements across Caco-2 monolayers of different organic and inorganic selenium: influence of sulfur compounds.

The transport and uptake of the most common Se compounds, selenate (SeO42-), selenite (SeO3(2-)), selenomethionine, and selenocystine, were investigated using confluent monolayers of Caco-2 cells, a human carcinoma cell line. Comparative measurements were performed in the absorptive (apical to basolateral side) and exsorptive (basolateral to apical side) directions. Apparent permeability coefficients (Papp), calculated from transport experiments in the absorptive direction, showed increasing values in the following rank order: about 1 x 10(6) cm/s < mannitol < SeO3(2-) < or = selenocystine < selenomethionine < SeO4(2-) < or = about 16 x 10(4) cm/s. The ratios of the Papp measured in the absorptive versus exsorptive directions indicated that only the organic forms presented a net polarized transport (Papp ratio >> 1), suggesting the presence of a transcellular pathway. No significant excretion was observed. The transport of selenomethionine was inhibited by its sulfur analog, methionine, suggesting a common transport mechanism. In contrast, an inhibition of the transport of selenocystine by cysteine was not observed. From the two substrates tested, sulfate and thiosulfate, only thiosulfate inhibited the transport of SeO4(2-) . This effect was also observed for SeO32- (i.e., was unspecific), which questioned the assertion of a common transport for sulfate and SeO4(2-) and may confirm the paracellular pathway of SeO42- suggested by the Papp ratio of about 1. The addition of glutathione (GSH) in large excess had no consequence on the passage of SeO3(2-) but strongly increased the uptake (about fourfold). The liquid chromatography - mass spectrometry (LC-MS) data showed that, in the ionic condition of incubation medium, GSH promptly reduced SeO3(2-) (< or = 2 min) in its elemental form Se0, which cannot ascribe to selenodiglutathione a direct role in the effect of GSH.

[Modifications in blood zinc and lead concentrations and ALA-dehydratase activity in optic neuropathy from alcohol and tobacco abuse]. / Modifications des concentrations sanguines du zinc, du plomb et de l'activité de l'ALA-dehydratase au cours des neuropathies optiques alcoolo-tabagiques.

Plasma red blood cell and total blood zinc levels were significantly decreased in 52 consecutives cases of bilateral, retrobulbar, axial optic neuropathy caused by chronic abuse of ordinary wine and/or beer and/or hard beverages and cigarette smoking principally in men in their forties [plasma zinc: 746 mg/l +/- 179 (n = 52), control 907 mg/l +/- 127; red blood cell zinc: 10,218 mg/l +/- 1,327 (n = 10), control 12,244 mg/l +/- 1,307; total blood zinc: 4,849 mg/l +/- 1,069 (n = 51), control 5,831 mg/l +/- 644]. In contrast, blood lead levels were increased in these cases - blood lead: 344 mg/l +/- 101 (n = 30), control 193 mg/l +/- 94. Activity of red blood cell delta-amino-levulinic acid dehydratase (ALA-dehydratase), a zinc dependent enzyme, was decreased [red blood cell ALA-dehydratase; 18,8 IU/l +/- 2,2 (n = 13), control 44,8 IU/l +/- 3,3]. Plasma magnesium was slightly decreased while serum copper was not significantly modified. Possible ophthalmological implication of these findings are discussed.

[Therapeutic affect of zinc sulfate on central scotoma due to optic neuropathy of alcohol and tobacco abuse]. / Effet thérapeutique du sulfate de zinc sur le scotome central des neuropathies optiques alcoolo-tabagiques.

The oral administration of 400 mg/day for one month of zinc sulphate, when compared with placebo, provoked normal plasma zinc level in treated patients, principally men in their forties, with bilateral, retrobulbar, axial, optic neuropathy related to excessive smoking and consumption of ordinary wine and/or beer and/or spirits. Treatment significantly improved visual capacity (measured with Friedmann analyser) of the central scotoma area (5 degrees).

[Changes in the plasma and erythrocyte concentrations of rubidium in patients with renal failure]. / Modifications des concentrations de rubidium plasmatique et globulaire chez les insuffisants rénaux.

Rubidium concentrations were measured by flame emission spectrophotometry in whole blood, plasma and red cells from male and female controls and from dialyzed and non-dialyzed patients of both sexes with chronic renal failure. Rubidium concentrations (mumol/l) in male and female controls respectively were: 2.29 +/- 0.29 and 1.96 +/- 0.46 in plasma: 36..79 +/- 5.90 and 30.19 +/- 6.11 in whole blood; 74.57 +/- 10.37 and 72.22 +/- 12.76 in erythrocytes. The red cell rubidium/plasma rubidium ratios were 32.6 in males and 38.3 in females. Compared with controls, dialyzed male and female patients showed, before dialysis, a decrease in rubidium concentrations of respectively -30% and -17% in plasma, -64% and -61% in whole blood, -40% and -33% in erythrocytes. A further decrease of 25% in rubidium plasma concentrations was observed after dialysis. Non dialyzed patients had an increase in plasma concentrations (+14% in males, +23% in females) and a decrease in erythrocyte concentrations (-16% in males, -20% in females) as compared with controls. Our data show that plasma and red cell rubidium concentrations are fairly constant and probably regulated in healthy subjects but vary considerably in patients with renal failure.

[Study of blood lead levels in a population of 616 subjects from the regions: Centre and Pays de Loire]. / Etude de la plombémie dans une population de 616 sujets des régions Centre et Pays de Loire.

OBJECTIVES: Low-lead level exposure has been associated with harmful health effects. Blood lead is the most widely used marker of exposure. In this work, our purpose was to evaluate the present level of blood lead in a group of 616 subjects from the general population living in two regions of France: Centre and Pays de Loire. METHODS: Subjects were randomly included in the study. Blood lead was measured by inductively coupled plasma mass spectrometry which is the most sensitive and specific method. RESULTS: The mean blood lead concentration of the population studied ranged from 46.7 +/- 20.5 micrograms/l in the 6-10 year old to 86.6 +/- 42.4 micrograms/l in the 50-66 year old subjects. From 385 children under 13 years old, 5 had blood lead higher than 100 micrograms/l, the maximum acceptable level recommended by the American Centers for Disease Control. Women had lower blood lead values than men and their levels remained unchanged until 50 years but increased beyond this age. CONCLUSION: Mean lead levels were low in this French population. There is however risk of higher levels in persons living in old housing.

[Lead blood levels in children under 6 years of age in the Mans region]. / Etude de l'imprégnation saturnine d'enfants de moins de 6 ans de la région du Mans.

OBJECTIVES: High lead levels in children can have a deleterious effect on intellectual development. We assessed blood lead levels in children in the Le Mans region. METHODS: Children aged between 6 months and 6 years were included in the study. Inclusion criteria were health status requiring a blood sample and amount of blood available after ordered tests sufficient for lead blood analysis. The study group included 365 children. RESULTS: Mean blood level in the 365 children was 37.2 +/- 20.6 micrograms/l. Six of the children had blood levels greater than 100 mu/l. None of the children had a level over 200 micrograms/l. Location of the home or date of construction of the home were not significantly correlated to blood lead levels, however blood lead levels were higher in children with neurological or behavioral disorders. This observation was made in a limited number of children. CONCLUSION: The risk of excessively high blood lead levels in children under 6 years of age is low in the Le Mans region. There is however a risk when old houses are renovated or in children with neurological or behavior disorders.

[A case of barium-peritoneum with neurological involvement. Importance of barium determination in biological fluids]. / Un cas de baryto-péritoine avec atteinte neurologique intérêt du dosage du baryum dans les liquides biologiques.

Barium in the peritoneum following a barium enema led to a severe and irreversible chronic barium poisoning, although from the abdominal and gastro-intestinal point of view, there were virtually no sequelae. Barium assay on the cerebro-spinal fluid of this patient revealed excessively high levels, which provides the laboratory evidence of the direct action of barium on the central nervous system. Barium assays on biological fluids after barium-peritoneum could be used to assess the degree of barium poisoning and may have prognostic value.