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Purpose In this study, we aimed to measure the apparent diffusion coefficients (ADCs) of major phosphorous metabolites in the human calf muscle at 7 T with a diffusion-weighted (DW)-STEAM sequence. Methods A DW-STEAM sequence with bipolar gradients was implemented at 7 T, and DW MR spectra were acquired in three orthogonal directions in the human calf muscle of six healthy volunteers (TE/TM/TR = 15 ms/750 ms/5 s) at three b-values (0, 800, and 1200 s/mm2). Frequency and phase alignments were applied prior to spectral averaging. Averaged DW MR spectra were analyzed with LCModel, and ADCs of 31P metabolites were estimated. Results Four metabolites (phosphocreatine (PCr), adenosine triphosphate (ATP), inorganic phosphate (Pi) and glycerol phosphorylcholine (GPC)) were quantified at all b-values with mean CRLBs below 10%. The ADC values of PCr, ATP, Pi, and GPC were (0.24 ± 0.02, 0.15 ± 0.04, 0.43 ± 0.14, 0.40 ± 0.09) × 10–3 mm2/s, respectively. Conclusion The ADCs of four 31P metabolites were successfully measured in the human calf muscle at 7 T, among which those of ATP, Pi and GPC were reported for the first time in humans. This study paves the way to investigate 31P metabolite diffusion properties in health and disease on the clinical MR scanner.

International audience; Serum osteocalcin was measured in patients with idiopathic hypoparathyroidism or pseudohypoparathyroidism, before or during the treatment with active vitamin D3 (1,25(OH)2D3 or 1 alpha OHD3). Serum osteocalcin and plasma 1,25(OH)2D were decreased in 11 patients with idiopathic hypoparathyroidism before treatment (2.8 +/- 1.27 ng/ml, P less than 0.001 and 14.3 +/- 4.27 pg/ml, P less than 0.001, respectively). In 24 patients with idiopathic hypoparathyroidism during the treatment, serum osteocalcin and plasma 1,25(OH)2D were within the normal range (4.5 +/- 0.74 ng/ml and 25.7 +/- 5.69 pg/ml, respectively). In five patients with pseudohypoparathyroidism before treatment, plasma 1,25(OH)2D was decreased (15.6 +/- 10.6 pg/ml, P less than 0.001) but serum osteocalcin was normal (7.8 +/- 1.66 ng/ml). In nine patients with pseudohypoparathyroidism during the treatment with active vitamin D3, serum osteocalcin and plasma 1,25(OH)2D were normal (6.8 +/- 1.47 ng/ml and 27.2 +/- 6.0 pg/ml, respectively). Serum PTH in pseudohypoparathyroidism was increased before treatment (0.70 +/- 0.34 ng/ml, P less than 0.05) and was normal during the treatment (0.50 +/- 0.13 ng/ml). In idiopathic hypoparathyroidism, the active vitamin D3 increased serum osteocalcin without PTH. In pseudohypoparathyroidism, PTH may increase serum osteocalcin or modulate the effect of active vitamin D3 on serum osteocalcin.

International audience; Phosphorus is a crucial component of major organic molecules such as nucleic acids, ATP and membrane phospholipids. It is present in soils in the form of inorganic phosphate (Pi), which has low availability and poor mobility. To cope with Pi limitations, plants have evolved complex adaptive responses that include morphological and physiological modifications. This review describes how the model plant Arabidopsis thaliana adapts its root system architecture to phosphate deficiency through inhibition of primary root growth, increase in lateral root formation and growth and production of root hairs, which all promote topsoil foraging. A better understanding of plant adaptation to low phosphate will open the way to increased phosphorus use efficiency by crops. Such an improvement is needed in order to adjust how we manage limited phosphorus stocks and to reduce the disastrous environmental effects of phosphate fertilizers overuse.

International audience; A new process was developed to achieve denitrifying biological phosphorus removal in wastewaters containing high levels of nitrate and phosphate with a low level of organic matter. This could particularly be useful in recirculating systems such as aquariums or fish farms to prevent accumulation of nitrate and phosphates and to avoid regular cost extensive and polluting water replacement. Phosphorus (P) was removed from the influent in a sequencing moving bed biofilm reactor, stored in the attached biomass and then cyclically removed from the biomass by filling the reactor with anaerobic water from a stock tank. Phosphate was accumulated in the stock tank which allowed for use as fertilizer. The feasibility of the experimental design was demonstrated by using the activated sludge model No. 3 (ASM3) complemented by the EAWAG Bio-P module implemented in the WEST simulation software. A pilot scale experiment was conducted in two identical reactors in two runs: one to treat water from a marine mesocosm, the other to treat a synthetic freshwater influent. No biological phosphorus removal was achieved during the seawater run. During the freshwater run, average P removal efficiency was 20%, of which 80% was attributed to biological removal and 20% to chemical precipitation. The absence of efficiency in seawater was attributed to the high concentration of calcium.

International audience; The incorporation of [3H-methyl] thymidine (3H-TdR) by Eubacteria, bacterial groups (alpha- and beta-Proteobacteria, Cytophaga-Flavobacter), and Archaea was measured according to temperature (7 and 17 degrees C) and nutrient levels (nitrogen, phosphorus, and carbon) in a lacustrine system (Sep, France). Short-term incubation was performed using a combination of microautoradiography and fluorescent in situ hybridization. Irrespective of the temperatures and nutrients studied, all the major phylogenetic bacterial groups assimilated 3H-TdR, and in most of the treatments studied, the proportion of beta-Proteobacteria taking up 3H-TdR was higher than those in the other bacterial groups. The proportion of Bacteria and different bacterial groups studied incorporating 3H-TdR were significantly increased, approximately 1.5-fold, by temperature except for alpha-Proteobacteria (7.6-fold). The nutrient effect was not the same for the different bacterial groups according to the temperatures studied. The proportions of alpha-Proteobacteria (at both temperatures) and Cytophaga-Flavobacter (at 7 degrees C) taking up 3H-TdR were significantly decreased and increased by adding N and P, respectively. Also, adding N, P, and C increased and decreased the percentage of beta-Proteobacteria incorporating 3H-TdR at 7 and 17 degrees C, respectively. The archaeal community showed a similar proportion of active cells (i.e., 3H-TdR) to the bacterial community, and uptake of 3H-TdR by Archaea was significantly increased (P < 0.05) by both temperature and nutrients. Thus, the assimilation of 3H-TdR by bacterial groups and Archaea in lacustrine system is significantly controlled by both temperature and nutrients.

International audience; Phosphorus is an abundant element in living organisms. It is traceable by its X-ray absorption spectrum which shows a strong white line at its K-edge, comparable with that observed for the L(III) edges of rare earth ions. With purple membrane, the variation of the imaginary part of the anomalous dispersion of phosphorus is found to be close to 20 anomalous electron units. Anomalous diffraction experiments at wavelengths near the K-absorption edge of phosphorus confirm this result. The spatial distribution of lipids derived from anomalous diffraction agrees with earlier results from neutron diffraction. Test experiments on single crystals of the carrier protein using 5.76 A photons gave a first low-resolution diffraction pattern. Various techniques of crystal mounting were attempted. In addition, fluorescence measurements on a solution of threonine synthase appear to hint at a change of the phosphate environment of the cofactor upon activator binding.

International audience; A novel 1H-13C correlated two-dimensional experiment, CT-HMQC-J, for the measurement of three-bond proton-phosphorus coupling constants in 13C-labeled DNA is described. The experiment is based on the intensity difference of 1H-13C cross peaks in the presence and absence of the proton-phosphorus coupling interaction during the constant-time period in HMQC experiment. The 3J(H, P) coupling constants can be easily extracted from the intensity ratios of the two experiments. The method has been applied to a uniformly 13C, 15N-labeled d(GGAGGAT) 7-mer DNA sample. The proton-phosphorus coupling constants determined from CT-HMQC-J, together with the other three-bond coupling constants, are used to determine beta and epsilon torsion angles. The introduction of beta and epsilon restraints has improved the convergence as well as the quality of d(GGAGGAT) structure.

International audience; Screening of chronic kidney disease (CKD) that includes estimation of the glomerular filtration rate (GFR) and evaluation proteinuria should be performed in all HIV-infected patients and these parameters have to be monitored annually in patients at higher risk for CKD. Black patients have a genetic predisposition to develop HIV-associated nephropathy. Suppression of HIV viral replication with antiretroviral therapy prevents the development of HIV-associated nephropathy or halts its progression. Kidney biopsy remains the most informative diagnosis test to differentiate various forms of kidney diseases in HIV-infected patients. Dosing antiretroviral agents with kidney metabolism should be adjusted when eGFR is bellow 50 mL/min/1.73 m(2). eGFR and serum phosphorus at baseline and during treatment should be carefully assessed in patients receiving tenofovir. Proximal renal tubular toxicity must be further evaluated in the presence of eGFR decrease and/or hypophosphatemia under tenofovir therapy.

International audience; Very little is known about the sub-cellular distribution of metal ions in cells. Some metals such as zinc, copper and iron are essential and play an important role in the cell metabolism. Dysfunctions in this delicate housekeeping may be at the origin of major diseases. There is also a prevalent use of metals in a wide range of diagnostic agents and drugs for the diagnosis or treatment of a variety of disorders. This is becoming more and more of a concern in the field of nanomedicine with the increasing development and use of nanoparticles, which are suspected of causing adverse effects on cells and organ tissues. Synchrotron-based X-ray and Fourier-transformed infrared microspectroscopies are developing into well-suited sub-micrometer analytical tools for addressing new problems when studying the role of metals in biology. As a complementary tool to optical and electron microscopes, developments and studies have demonstrated the unique capabilities of multi-keV microscopy: namely, an ultra-low detection limit, large penetration depth, chemical sensitivity and three-dimensional imaging capabilities. More recently, the capabilities have been extended towards sub-100nm lateral resolutions, thus enabling sub-cellular chemical imaging. Possibilities offered by these techniques in the biomedical field are described through examples of applications performed at the ESRF synchrotron-based microspectroscopy platform (ID21 and ID22 beamlines).

e-mail plassard@supagro.inra.fr; UMR DAP équipe DGB; International audience; Ectomycorrhizal symbiosis markedly improves plant phosphate uptake, but the molecular mechanisms underlying this benefit are still poorly understood. We identified two ESTs in a cDNA library prepared from the ectomycorrhizal basidiomycete Hebeloma cylindrosporum with significant similarities to phosphate transporters from the endomycorrhizal fungus Glomus versiforme and from non-mycorrhizal fungi. The full-length cDNAs corresponding to these two ESTs complemented a yeast phosphate transport mutant (Deltapho84). Measurements of (33)P-phosphate influx into yeast expressing either cDNA demonstrated that the encoded proteins, named HcPT1 and HcPT2, were able to mediate Pi:H(+) symport with different affinities for Pi (K(m) values of 55 and 4 mum, respectively). Real-time RT-PCR showed that Pi starvation increased the levels of HcPT1 transcripts in H. cylindrosporum hyphae grown in pure culture. Transcript levels of HcPT2 were less dependent on Pi availability. The two transporters were expressed in H. cylindrosporum associated with its natural host plant, Pinus pinaster, grown under low or high P conditions. The presence of ectomycorrhizae increased net Pi uptake rates into intact Pinus pinaster roots at low or high soil P levels. The expression patterns of HcPT1 and HcPT2 indicate that the two fungal phosphate transporters may be involved in uptake of phosphate from the soil solution under the two soil P availability conditions used.

International audience; BACKGROUND: In the setting of kidney transplantation, cinacalcet has been given, mainly, once daily, but also twice daily. The aims of this prospective study were to assess the acute pharmacodynamic effect of cinacalcet administrated once or twice daily to kidney transplant patients with normal renal function and persisting hypercalcaemia due to hyperparathyroidism and to evaluate 1-year efficacy and tolerance of cinacalcet given at a dose of 30 mg b.i.d. METHODS: Eleven patients, who received a transplant 6 (6-59) months previously, were included in the study. A first kinetic was done after administration of 60 mg of cinacalcet at 8 a.m. After a washout period of 1 week, the second kinetic was performed with cinacalcet given at 30 mg b.i.d within a 12-h period. RESULTS: During both kinetics, serum calcium (sCa), ionized calcium (sCa(2+)), albumin-corrected Ca and parathyroid hormone (PTH) levels decreased significantly. At 24 h after the second kinetic, sCa(2+) was significantly lower. After 1 year of cinacalcet treatment, given at the dose of 30 mg b.i.d., there was a significant decrease in sCa, sCa(2+), PTH levels and calcium x phosphorus (Ph) product. In contrast, Ph levels increased significantly. There was no significant change in renal function. CONCLUSION: Once- or twice-daily acute administration of cinacalcet to kidney-transplant patients has similar efficacy. One-year administration of cinacalcet, given as two daily doses, is safe and efficient.

International audience; Small eukaryotes (0.2-5 microm) in hyper-eutrophic conditions were described using terminal restriction fragment length polymorphism and cloning-sequencing, and were related to environmental variables both by an experimental approach and by a temporal field study. In situ analysis showed marked temporal variations in the dominant terminal restriction fragments (T-RFs), which were related to environmental variables such as nutrient concentrations and metazooplankton composition. To monitor the responses of the small-eukaryote community to top-down (absence or presence of planktivorous fish) and bottom-up (low or high nitrogen and phosphorus addition) effects, a cross-classified design mesocosm experiment was used. Depending on the type of treatment, we recorded changes in the diversity of T-RFs, as well as modifications in phylogenetic composition. Centroheliozoa and Cryptophyta were found in all types of treatment, whereas Chlorophyta were specific to enclosures receiving high nutrient loadings, and were associated either with LKM11 and 'environmental sequences'. Cercozoa and Fungi were not detected in enclosures receiving high nutrient loadings and fishes. Our results showed that resources and top-down factors are both clearly involved in shaping the structure of small eukaryotes, not only autotrophs but also heterotrophs, via complex interactions and trophic cascades within a microbial loop, notably in response to nutrient loading.

International audience; As first defensive line, monocytes are a pivotal cell population of innate immunity. Monocyte activation can be relevant to a range of immune conditions and responses. Here we present new insights into the activation of monocytes by a series of phosphonic acid-terminated, phosphorus-containing dendrimers. Various dendritic or subdendritic structures were synthesized and tested, revealing the basic structural requirements for monocyte activation. We showed that multivalent character and phosphonic acid capping of dendrimers are crucial for monocyte targeting and activation. Confocal videomicroscopy showed that a fluorescein-tagged dendrimer binds to isolated monocytes and gets internalized within a few seconds. We also found that dendrimers follow the phagolysosomial route during internalization by monocytes. Finally, we performed fluorescence resonance energy transfer (FRET) experiments between a specifically designed fluorescent dendrimer and phycoerythrin-coupled antibodies. We showed that the typical innate Toll-like receptor (TLR)-2 is clearly involved, but not alone, in the sensing of dendrimers by monocytes. In conclusion, phosphorus-containing dendrimers appear as precisely tunable nanobiotools able to target and activate human innate immunity and thus prove to be good candidates to develop new drugs for immunotherapies.

With its good properties of biocompatibility and bioactivity hydroxyapatite (HA) is highly used as bone substitutes and as coatings on metallic prostheses. In order to improve the bioactive properties of HA, we have elaborated Zn2+ doped hydroxyapatite. Zn2+ ions substitute for Ca2+ cations in the HA structure and four Zn concentrations (Zn/Zn + Ca) were prepared at 0.5, 1, 2 and 5 at.%. To study physico-chemical reactions at the materials periphery, we immersed the bioceramics into biological fluids for intervals from 1 day to 20 days. The surface changes were studied at the nanometer scale by scanning transmission electron microscopy associated with energy dispersive X-ray spectroscopy. After 20 days of immersion, we observed the formation of a calcium–phosphate layer at the periphery of the HA doped with 5% zinc. This layer contains magnesium and its thickness was around 200 nm. Formation of this Ca–P–Mg layer represents the bioactive properties of 5% Zn-substituted hydroxyapatite. This biologically active layer improves the properties of HA and will permit a chemical bond between the ceramic and bone.

By combining electron tomography with energy-filtered electron microscopy, we have shown the feasibility of determining the three-dimensional distributions of phosphorus in biological specimens. Thin sections of the nematode, Caenorhabditis elegans were prepared by high-pressure freezing, freeze-substitution and plastic embedding. Images were recorded at energy losses above and below the phosphorus L2,3 edge using a post-column imaging filter operating at a beam energy of 120 keV. The unstained specimens exhibited minimal contrast in bright-field images. After it was determined that the specimen was sufficiently thin to allow two-window ratio imaging of phosphorus, pairs of pre-edge and post-edge images were acquired in series over a tilt range of +/-55 degrees at 5 degrees increments for two orthogonal tilt axes. The projected phosphorus distributions were aligned using the pre-edge images that contained inelastic contrast from colloidal gold particles deposited on the specimen surface. A reconstruction and surface rendering of the phosphorus distribution clearly revealed features 15-20 nm in diameter, which were identified as ribosomes distributed along the stacked membranes of endoplasmic reticulum and in the cytoplasm. The sensitivity of the technique was estimated at < 35 phosphorus atoms per voxel based on the known total ribosomal phosphorus content of approximately 7000 atoms. Although a high electron dose of approximately 10(7)e/nm2 was required to record two-axis tilt series, specimens were sufficiently stable to allow image alignment and tomographic reconstruction.

This paper is the third part of a series of papers dealing with the development of digital filters for the extraction of information from electron energy loss spectra, when the signal-to-background is very weak, as it is the case for elements in weak concentration. Three new filtering approaches are investigated: the use of high-order derivatives (typically, the fourth order derivative of a Gaussian), the use of homomorphic filtering (working on logarithmically-transformed spectra) and the use of adaptive filtering, taking into account the local background shape. These signal processing methods are applied to real spectra to demonstrate and comment their effects in three different cases of signal and background shapes related to calcium, phosphorus and boron detection in definite thickness organic matrix.

Hydroxyapatite used as bone replacement can lead to particle release in the implantation site. These particles interact with monocytes, which are the first immune cells to colonize the implant and an inflammatory site. Thanks to cryo-X-ray microanalysis, we can observe cells in a state close to the physiological one and we have access to diffusible ions. We paid particular attention to the potassium-to-sodium ratio, which is one of the best viability criteria. We used this method to study the interaction between three hydroxyapatite particles treated at three different temperatures (not treated, treated at 600 °C and 1180 °C), and monocytes. In the culture condition, the hydroxyapatite treated at 1180 °C underwent the least dissolution. We demonstrate that monocytes were altered by the three hydroxyapatite particles. The hydroxyapatite particules treated at 600 °C were found to be more toxic. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 58: 238–246, 2001

International audience; The effects of almitrine on ATPase/ATPsynthase previously described in beef heart mitochondria (Rigoulet et al. (1990) Biochim. Biophys. Acta 1018, 91-97) are also observed in liver mitochondria isolated from rats older than 7 weeks. In contrast, in rats younger than 5 weeks, almitrine at the same concentration has no effect on the ATPase/ATPsynthase complex. This age-dependent action of almitrine is well correlated with age-dependent modifications of two fatty acids: linoleic and docosahexaenoic acids. The possibility of a change in H+/ATP stoichiometry of the ATPase/ATPsynthase induced by almitrine seems related to more general modifications of membrane properties during growth of the rat.

International audience; Apparent diffusion coefficients (Da) of individual metabolites can be studied in vivo by diffusion NMR spectroscopy using an echo sequence sensitized to molecular motion. The methods are based on the echo attenuation due to phase dispersion resulting from incoherent displacement during the diffusion time. As the displacement of metabolites by diffusion in vivo can be affected by compartment size, temperature, adsorption processes, etc., the presented methods are potentially useful in studying such phenomena in vivo. Here, the methods are applied to phosphocreatine in the rat quadriceps muscle. It is demonstrated that the displacement of phosphocreatine resembles free diffusion for short diffusion times but becomes limited as a result of boundaries due to compartmentation for longer diffusion times. The limit of the displacement indicates an apparent average size of 44 microns of the compartment in the direction of the diffusion gradient. As the gradient was applied approximately parallel (angle less than 25 degrees) to the muscle fiber, this result indicates that phosphocreatine moves freely in the cytosol but is limited by the boundaries of the muscle cells. Error analyses are performed with regard to motion artifacts and gradient performance. The methods were tested extensively for distilled water and free metabolites.