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In this study, we report a rapid sonochemical synthesis of monodisperse nonaggregated Fe(3)O(4)@SiO(2) magnetic nanoparticles (NPs). We found that coprecipitation of Fe(II) and Fe(III) in aqueous solutions under the effect of power ultrasound yields smaller Fe(3)O(4) NPs with a narrow size distribution (4-8 nm) compared to the silent reaction. Moreover, the coating of Fe(3)O(4) NPs with silica using an alkaline hydrolysis of tetraethyl orthosilicate in ethanol-water mixture is accelerated many-fold in the presence of a 20 kHz ultrasonic field. The thickness of the silica shell can be easily controlled in the range of several nanometers during sonication. Mossbauer spectra revealed that nonsuperparamagnetic behavior of obtained core-shell NPs is mostly related to the dipole-dipole interactions of magnetic cores and not to the particle size effect. Core-shell Fe(3)O(4)@SiO(2) NPs prepared with sonochemistry exhibit a higher magnetization value than that for NPs obtained under silent conditions owing to better control of the deposited silica quantities as well as to the high speed of sonochemical coating, which prevents the magnetite from oxidizing.

The sorption of selenite ions onto Fe3O4 and Fe/Fe3C nanoparticles (NPs) was studied in aqueous solutions under anoxic conditions using gamma spectrometry and X-ray absorption spectrometry (XAS) techniques. This is the first study related to the remedial applications of Fe/Fe3C NPs. FesO4 NPs have been prepared by conventional coprecipitation of Fe(II) and Fe(III) in basic solutions. Stable Fe/Fe3C NPs have been prepared by Fe(CO)5 sonicating in diphenylmethane solutions and subsequently annealing the as-prepared product. Kinetic study demonstrated that Se(IV) sorption is extremely rapid: the equilibrium is reached in approximately 10 and 30 min for Fe3O4 and Fe/Fe3C NPs, respectively, at pH = 4.9-5.1 in solutions of 0.1 M NaCl. The distribution coefficients are also very high for both kinds of NPs (Kd > 3000). Increasing the pH to 10.3 or adsorption of organic ligands, like L-lysine or dodecanoate, at the surface of NPs causes the decrease in Kd values. However, even in these cases Kd values exceed 150. Magnetic NPs loaded with selenium can be easily and completely removed from solution with a 0.4 T permanent magnet. XAS study revealed the absence of Se(IV) reduction during the sorption onto Fe3O4 NPs in the pH range of 4.8-8.0. By contrast, the removal of Se(IV) with Fe/Fe3C NPs in anaerobic conditions occurs via Se(IV) reduction to Se(-II) and subsequent formation of iron selenide at the particle surface. Thus, the Fe/Fe3C NPs are superior to Fe3O4 NPs due to their ability to immobilize rapidly and irreversibly Se(IV) via reductive mechanism. Presumably these particles could be also effective for the removal of other contaminants such as hexavalent chromium, actinides, technetium, and toxic organic compounds.

Washed cell suspensions of the anaerobic hyperthermophilic archaea Thermococcus pacificus and Thermoproteus uzoniensis and the anaerobic thermophilic gram-positive bacteria Thermoterrabacterium ferrireducens and Tepidibacter thalassicus reduced technetium [(99)Tc(VII)], supplied as soluble pertechnetate with molecular hydrogen as an electron donor, forming highly insoluble Tc(IV)-containing grayish-black precipitate. Apart from molecular hydrogen, T. ferrireducens reduced Tc(VII) with lactate, glycerol, and yeast extract as electron donors, and T. thalassicus reduced it with peptone. Scanning electron microscopy and X-ray microanalysis of cell suspensions of T. ferrireducens showed the presence of Tc-containing particles attached to the surfaces of non-lysed cells. This is the first report on the reduction in Tc(VII) by thermophilic microorganisms of the domain Bacteria and by archaea of the phylum Euryarchaeota.

Abstract It is shown for the first time that haloalkaliphilic bacteria, isolated from soda-lake environments were capable of reducing Tc(VII)O(4) (-) to the Tc(V), Tc(IV) and Tc(III) at pH 10 in carbonate medium, whereas no reduction took place without bacteria or in the presence of dead biomass. After 34 h of incubation, 55% remained as Tc(VII), 36% was found as Tc(IV) and 8% as Tc(V) and after 2 months 80% of the technetium was reduced. Technetium has a toxic effect on bacteria. Reduction of TcO(4) (-) was drastically decreased at concentration above 1.5 mM. The microbial reduction has been suggested as a potential mechanism for the removal of Tc from contaminated environments or waste streams.

Leaves of plants have the ability to accumulate the long-lived fission product (99)Tc. In the present work, an attempt was made to separate and characterize technetium species formed in maize grown on soil contaminated with Tc(VII)O(4)(-) solution. Data obtained from selective extraction, a Phosphorimager and liquid scintillation were employed.

Background: Peripartum cardiomyopathy is a frequent condition of unknown origin in Sahelian West Africa., Objective: To identify the nutritional and trace-elements status, plasma concentrations of albumin, pre-albumin (trans-thyretin), retinol binding protein, copper, selenium and zinc were assayed in 35 African women living in a Sahelian area, hospitalized in the Hôpital national, Niamey (Republic of Niger) with peripartum cardiac failure due to peripartum cardiomyopathy., Methods: Plasma albumin was assayed by an automatic method; pre-albumin and retinol binding protein by radial immunodiffusion (Mancini's method); and plasma copper, selenium and zinc by neutron activation and particle-induced X-ray emission. The results were compared with those for a control group of African women living under the same conditions but without peripartum cardiac failure., Results: Plasma albumin and pre-albumin were lower in patients with peripartum cardiomyopathy than they were in controls (P < 0.001). For retinol binding protein, the difference was not statistically significant. The plasma concentrations of selenium and zinc were lower in patients than they were in controls (48 +/- 25 versus 77 +/- 16 ng/ml and 0.90 +/- 0.21 versus 1.17 +/- 0.25 micrograms/ml, respectively, P < 0.001) whereas that of copper was higher (2.03 +/- 0.37 versus 1.23 +/- 0.20 micrograms/ml, P < 0.001). The mean zinc: copper ratio was lower in patients than it was in controls (0.44 versus 0.95)., Conclusion: Such differences may be aetiological factors or biological consequences of the peripartum cardiac failure due to cardiomyopathy. Nutritional abnormalities may play a role in the pathophysiology of the disease.

To investigate the effects of selenium or beta-carotene supplementation in human immunodeficiency virus (HIV)-infected patients, who are known to have deficiencies of selenium and vitamin A, we evaluated the blood enzymatic antioxidant system, including superoxide dismutase (SOD), selenodependent glutathione peroxidase (GPX), and catalase (Cat); glutathione (GSH) status; and plasma selenium concentration. The placebo group consisted of 18 HIV-infected patients with no supplementation, the selenium group was composed of 14 patients receiving oral selenium treatment, and the beta-carotene group comprised 13 patients receiving oral beta-carotene supplementation. All groups were studied for 1 y. At the beginning of the study, a significantly higher SOD activity (P < 0.001) was observed in all HIV-infected patients compared with uninfected control subjects, and GPX activity at baseline was higher in the placebo (P < 0.004) and selenium (P < 0.014) groups than in the control subjects. These higher enzyme activities could be related to an increased synthesis of these enzymes in erythrocyte precursors under oxidative stress. Moreover, we observed significantly lower GSH values in all HIV-infected patients than in control subjects at the beginning of the study (P < 0.001). After selenium or beta-carotene supplementation, no significant difference was observed for SOD activity compared with baseline. On the contrary, GPX activity increased significantly after selenium treatment (P < 0.04 between 3 and 6 mo), whereas a slight increase was found after beta-carotene treatment. Similarly, a significant increase in GSH values was observed at 12 mo compared with baseline both after selenium supplementation (P < 0.001) and beta-carotene supplementation (P < 0.01). Because GPX and GSH play an important role in the natural enzymatic defense system in detoxifying hydrogen peroxide in water, selenium supplementation could be of great interest in protecting cells against oxidative stress. The lower efficiency of beta-carotene could be attributed to the seriousness of the pathology at the time of recruitment into the beta-carotene group.

The effect of the addition of MgCl(2) and of taurine on the concentration and distribution of ions, present in physiological fluid, in epithelial (EL) and compact (CL) layers of the human amniotic membrane has been investigated using the Bordeaux nuclear microprobe. Particle induced X-ray emission and Rutherford backscattering spectrometry techniques had been used to provide quantitative measurements. In physiological medium (Hanks' solution), the monovalent ions (Na+, K+, Cl-) concentrations were identical in both layers. This data indicates that the compact layer acts as a buffer which fix minerals. Mg(2)+, Ca(2)+ and phosphorus levels were higher in EL than in CL. The addition of MgCl(2) in Hanks' solution induced a decrease of the monovalent ions concentration in both layers except Na+ level in EL which remained constant, an increase of the Mg(2)+ level in both layers while the Ca(2)+ and phosphorus remained constant. Addition of taurine in the Hanks' solution implicated several observations: taurine had no effect on the Na+, Mg(2)+, Ca(2)+ and phosphorus levels in EL and CL, but decreased the K+ and Cl- concentrations in both layers. The quantitative results may be related to electrophysiological observations on ionic exchanges through channels and paracellular pathways. The nuclear microanalysis processing may be of great interest to explain pregnancies complicated by poly or oligohydramnios.

Platinum and trace metal distributions of a human ovarian adenocarcinoma cell line, IGROV1, and a subline resistant to the antitumor agent cisplatin were compared using nuclear microprobe analysis. The cisplatin-resistant cell line IGROV1-DDP exhibited a cytologically heterogeneous cell population. Two subpopulations were distinguished, small mononuclear cells, morphologically similar to the parental cells IGROV1, and enlarged polynuclear cells. Quantitative mapping of platinum and essential trace metal such as manganese, iron, copper and zinc was performed at the cellular level. Elemental maps were obtained with 2 mu m spatial resolution. Platinum appeared uniformly distributed within the cells, in all cell types. The same was true for copper and zinc. In some cases, iron maps showed preferential localization in the perinuclear region, especially in IGROV1-DDP polynuclear cells. Cisplatin resistance was associated with decreased platinum and iron concentrations and increased levels of copper and zinc. Decreased drug accumulation was encountered in both subpopulations of the resistant cell line. In contrast, high inter-individual variation of copper content was noticed in this cell line suggesting that in vitro cisplatin selection of human ovarian adenocarcinoma resistant cells can bring about the emergence of distinct cellular phenotypes.

The effect of taurine on the Na(+), K(+), Cl(-) concentration and distribution in epithelial and compact layers of the human amniotic membrane had been investigated using the Bordeaux nuclear microprobe. Particle induced X-ray emission and Rutherford backscattering spectrometry techniques had been used to provice quantitative measurements. In physiological medium, the monovalent ions concentrations were identical in epithelial and compact layers. The addition of taurine in Hanks' physiological fluid had no effect on Na(+) concentration, but decreased K(+) and Cl(-) concentration in both layers. The quantitative results were related to electrophysiological observations on the effect of taurine on ionic exchanges through channels and paracellular pathways.

The effect of the addition of MgCl2 on the Na+, K+, and Cl- concentration and distribution in epithelial and compact layers of the human amniotic membrane was investigated using the Bordeaux nuclear microprobe. Particle-induced X-ray emission and Rutherford backscattering spectrometry techniques were used to provide quantitative measurements. In physiological medium (Hanks' solution), the monovalent ion concentrations were identical in both layers. The addition of Mg2+ ions in Hanks' solution induced a decrease of, K+, and Cl- concentration in both layers and, Na+ concentration in the compact layer. The results obtained from nuclear microanalysis might be explained from electrophysiological data which indicate that the addition of Mg2+ ions results in an increase in the cellular, paracellular and exchanger ion pathways.

Objective: To investigate red blood cell (RBC) and plasma fatty acids (FA) in HIV-positive patients in relation to oxidative stress and nutritional or immunological status., Design and Methods: FA, plasma selenium, vitamins A and E were measured in 95 patients divided into four groups according to CD4 cells., Results: Poly- and di-unsaturated FA (PUFA, DUFA) decreased and saturated FA (SFA) increased in RBC in the patients below 400/mm3 and in plasma in the patients below 50/mm3. RBC SFA correlated to CD4 cells, PUFA to MDA. Unlike vitamin E, plasma vitamin A and selenium decreased in most groups. Plasma SFA and MUFA correlated negatively to selenium and PUFA and DUFA to vitamin E. No correlation was found between PUFA and nutritional markers., Conclusion: FA seem to be modified during HIV infection by oxidative stress and disease evolution, but not by denutrition.

The present study aimed to determine plasma lipid levels in 95 HIV-infected patients divided into four groups according to the CD4 lymphocyte counts comparatively to a control group of 20 HIV-negative normolipidaemic subjects. A relationship between lipidic abnormalities and immune or nutritional status was also investigated. The patients below 200 CD4 lymphocyte mm-3 (groups 1 and 2) had significantly lower total cholesterol than the controls. The patients below 400 CD4 lymphocytes mm-3 (groups 1, 2, 3) had significantly higher triglycerides and Lp(a) but lower LDL-cholesterol than the controls. In all HIV-positive patients, whatever their CD4 lymphocyte count, HDL-C and apoA1 were lower than in the controls. By multivariate analysis triglycerides were positively correlated to acute opportunistic infections and to interferon-alpha levels, while cholesterol was negatively correlated to TNF-alpha, and LDL-C was positively correlated to albuminaemia. The latter parameter was the only lipidic value to correlate with nutritional markers. The contamination route, or the presence of wasting, was not correlated to any lipidic disorder.

A specific selenium deficiency is a risk factor for Keshan disease, an endemic cardiomyopathy observed in China. In a Sahelian area of Niger, plasma selenium concentration was measured by neutronic activation and particle induced X-ray emission in 35 black African women with peripartum cardiomyopathy and 36 breast-feeding women without cardiac failure as controls. The plasma selenium concentration in patients was lower (48 +/- 25 ng/ml, mean +/- standard deviation) than in controls (77 +/- 16 ng/ml) (P less than 0.0001). Moreover, 40% (14/35) patients with peripartum cardiomyopathy had very low plasma selenium concentrations, below 45 ng/ml, versus none in controls. A low plasma selenium concentration is a risk factor for the Sahelian peripartum cardiomyopathy.

Antioxidant status can be evaluated by blood selenium, vitamins A and E. The level of selenium was determined in whole blood, erythrocytes and plasma of 170 French people (70-95 years old) healthy and with intercurrent illness, by using PIXE (proton-induced X-ray emission analysis). These results are discussed with other values from the literature. Plasma levels of vitamins A and E have been measured by HPLC. All data were compared with those obtained for younger subjects. Healthy elderly people residing in a geriatric home received selenium supplements during 1 month. The influence of this supplementation brought to light a deficiency for this trace element. The correlation of aging and nutritional requirements with immune function, heart and cancer death rate is presented and discussed.

A new dietary factor, the glucose tolerance factor (GTF), was reported in 1957 that improved impaired glucose tolerance in rats. Most studies on GTF have used brewer's yeast as the starting material, and it has been postulated that the active material is a low-mol wt organic complex containing Cr3+. It seemed thus important to isolate an active GTF from chromium-rich yeast (228 ppm Cr) obtained by incubation with chromium and to compare each fraction with corresponding ones from untreated yeast (0.48 ppm Cr). We developed an isolation and purification procedure by fractionation of yeast extract on an anion and cation exchange resin, and tested the GTF activity (glucose oxidation) on rat adipocytes. PIXE (proton-induced X-ray emission) was used to measure the chromium content of the individual fraction. Individual fractions with GTF activity did not differ between Cr-rich and Cr-deficient yeast, and there was no relationship between Cr content and GTF activity. This does not support the hypothesis that chromium is an obligatory constituent of the GTF, assuming that GTF is a unique substance.

Plasma chromium concentrations have been determined for 150 patients. These were subjected to coronary artery cineangiography and thereby divided into three groups: group CAD (those with coronary artery disease), group HD (those with heart disease, but no CAD) and group N (those with no CAD and no HD). Weighted, average chromium levels for these groups were 1.05, 1.72, and 8.51 ng/mL, respectively. The distributions of plasma chromium levels for the three groups suggest that an upper limit for plasma chromium may be established (6 ng/mL in this work) beyond which CAD may be considered to be extremely unlikely, thus eliminating the need for a certain number of cineangiographic examinations.

Recent measurements have demonstrated that plasma chromium levels in patients with coronary artery disease are very much lower than in normal subjects. A review of the literature concerning the physiological functions of chromium (or GTF) shows it to be implicated in most of the known factors of cardiovascular risk, via its effect on insulin levels and activities. Chromium deficiency leads to impaired lipid and glucide metabolism and results in high circulating insulin levels, the probable consequences of which suggest that chromium deficiency may be a primary risk factor in cardiovascular disease.

Serum vanadium levels have been measured by neutron activation analysis. They are higher (3.10 +/- 1.38 ng/mL) in patients suffering depressive illness than in normal subjects (0.67 +/- 0.32 ng/mL).

Vanadium concentrations have been measured in the serum of 23 healthy subjects by neutron activation analysis, with post-irradiation chemical separation. The values obtained fall in a fairly narrow range (260-1300 ng/L, mean 670 ng/L), which suggests a physiological role for this element. We checked the method by analysis of standard (U.S. National Bureau of Standards) water samples and serum samples supplemented with 48V, and we found excellent agreement with expected results in both cases. We consider the reported results for human serum to be more reliable than those obtained by atomic absorption spectroscopy.