ABSTRACT
Bone is the main target organ for the storage of several toxic metals, including uranium. But the mode of action of uranium on bones remains poorly understood. To better assess the impact of uranium on bone cells, synthetic biomimetic apatites encompassing a controlled amount of uranium were prepared and analyzed. This study revealed the physicochemical impact of uranium on apatite mineralization: the presence of the metal induces a loss of crystallinity and a lower mineralization rate. The prepared samples were then used as substrates for bone cell culture. Osteoblasts were not sensitive to the presence of uranium in the support, whereas previous results showed a deleterious effect of uranium introduced into a cell culture solution. This work should therefore have some original prospects within the context of toxicological studies concerning the effect of metallic cations on bone cell systems.
Subject(s)
Apatites/chemistry , Biomimetic Materials/chemistry , Uranium/chemistry , Animals , Cell Proliferation , Cell Survival , Cells , Mice , Microscopy, Electron, Scanning , Osteoblasts/cytologyABSTRACT
The classical simulated body fluids method cannot be employed to prepare biomimetic apatites encompassing metallic ions that lead to very stable phosphates. This is the case for heavy metals such as uranium, whose presence in bone mineral after contamination deserves toxicological study. We have demonstrated that existing methods, based on alternate dipping into calcium and phosphate ions solutions, can be adapted to achieve this aim. We have also especially studied the impact of the presence of carbonate ions in the medium as these are necessary to avoid hydrolysis of the contaminating metallic cations. Both the apatite-collagen complex method and a standard chemical (STD) method employing only mineral solutions lead to biomimetic apatites when calcium and carbonate ions are introduced simultaneously. The obtained materials were fully characterized and we established that the STD method tolerates the presence of carbonate ions much better, and this leads to homogeneous samples. Emphasis was set on the repeatability of the method to ensure the relevancy of further work performed on series of samples. Finally, osteoblasts cultured on these samples also proved a similar yield and standard-deviation in their adenosine triphosphate content when compared to commercially available substrates designed to study of such cell cultures.
Subject(s)
Apatites/chemistry , Biomimetic Materials/chemistry , Carbon/chemistry , Ions/chemistry , Osteoblasts/drug effects , 3T3 Cells , Animals , Bone and Bones/drug effects , Calcium/chemistry , Cations , Cell Survival , Collagen/chemistry , Collagen Type I/chemistry , Durapatite/chemistry , Femur/pathology , Hydrolysis , Metals, Heavy/chemistry , Mice , Microscopy, Atomic Force , Microscopy, Electron, Scanning , Osteoblasts/metabolism , Rats , Spectroscopy, Fourier Transform Infrared , Spectrum Analysis, Raman , Surface Properties , Uranium/chemistry , X-Ray DiffractionABSTRACT
The dengue fever virus (DENV) and the yellow fever virus (YFV) are members of the genus flavivirus in the family Flaviviridae. An estimated 50-100 million cases of DENV infections occur each year and approximately half a million patients require hospitalization. There is no vaccine or effective antiviral treatment available. There is an urgent need for potent and safe inhibitors of DENV replication; ideally such compounds should have broad-spectrum activity against flaviviruses. We here report on the in vitro activity of 3',5'di-O-trityluridine on flavivirus replication. The compound results in a dose-dependent inhibition of (i) DENV- and YFV-induced cytopathic effect (CPE) (EC50 values in the low micromolar range for the 4 DENV serotypes), (ii) RNA replication (DENV-2 EC50=1.5 µM; YFV-17D EC50=0.83 µM) and (iii) viral antigen production. Antiviral activity was also demonstrated in DENV subgenomic replicons (which do not encode the structural viral proteins) (EC50=2.3 µM), indicating that the compound inhibits intracellular events of the viral replication cycle. Preliminary data indicate that the molecule may inhibit the viral RNA-dependent RNA polymerase.