Biomedical subjects

Jean Michel

Publications and source records attributed to Jean Michel.

3 recordsLinked to original sources

PubMed2006

Development and in vitro characterization of sol-gel derived CaO-P2O5-SiO2-ZnO bioglass.

A CaO-P(2)O(5)-SiO(2)-ZnO bioglass was formed by the sol-gel technique and characterized by Raman spectroscopy, X-ray diffraction, energy dispersive X-ray analysis (EDXA) and scanning electron microscopy (SEM). The surface reactivity of the resultant glass-ceramic specimens was analyzed by immersion studies in simulated body fluid (SBF). SEM-EDXS and inductively coupled plasma atomic emission spectrometry techniques were used to monitor changes in the glass surface and SBF composition. Osteoblast cell culture experiments were performed to assess the biocompatibility and the alkaline phosphatase activity. Cell counts of the osteoblasts cultured on the bioglass samples were studied and compared with the polystyrene plates. The cells cultured on the bioglass disks consistently showed a higher alkaline phosphatase activity and cell counts compared to cells cultured on either polystyrene plates or the base CaO-P(2)O(5)-SiO(2) bioglass. This was due to cell proliferation and differentiation promoted by the zinc-substituted bioglass.

Animals↗

PubMed2005

The distribution of light elements in biological cells measured by electron probe X-ray microanalysis of cryosections.

The intracellular distribution of the elements carbon, nitrogen, and oxygen was measured in cultured rat hepatocytes by energy dispersive electron probe X-ray microanalysis of 100-nm-thick freeze-dried cryosections. Electron irradiation with a dose up to 106 e/nm2 caused no or merely negligible mass loss in mitochondria and in cytoplasm. Cell nuclei lost carbon, nitrogen, and-to a clearly higher extent-oxygen with increasing electron irradiation. Therefore, electron doses less than 3 x 105 e/nm2 were used to measure the subcellular compartmentation of carbon, nitrogen, and oxygen in cytoplasm, mitochondria, and nuclei of the cells. The subcellular distribution of carbon, nitrogen, and oxygen reflects the intracellular compartmentation of various biomolecules. Cells exposed to inorganic mercury before cryofixation showed an increase of oxygen in nuclei and cytoplasm. Concomitantly the phosphorus/nitrogen ratio decreased in mitochondria. The data suggest mercury-induced production of ribonucleic acid (RNA) and decrease of adenosine triphosphate (ATP). Although biomolecules cannot be identified by X-ray microanalysis, measurements of the whole element spectrum including the light elements carbon, nitrogen, and oxygen can be useful to study specific biomolecular activity in cellular compartments depending on the functional state of the cell.

Animals↗

PubMed2002

Light elements quantification in stimulated cells cryosections studied by electron probe microanalysis.

The quantification of intracellular light elements such as carbon, nitrogen and oxygen may be useful in understanding the biological mechanisms, for example the generation of nitric oxide which is involved in apoptosis and inflammatory reaction. Electron energy loss spectroscopy (EELS) coupled with scanning transmission electron microscopy is a useful method to detect light elements in thin cryosections. Recent developments of X-ray detectors with ultra-thin protection windows allows the detection of such elements by energy dispersive X-ray spectroscopy. In the present study, we have demonstrated using both methods that the stimulation of BV-2 murine microglial cell line by gamma-interferon and lipopolysaccharide leads to the increase of intracellular oxygen concentration and no change in the intracellular nitrogen concentration. This indicates the use of exogeneous molecular oxygen in response to the stimulation. But the increase of oxygen concentration detected could not be only due to NO expression because the NO production was 1000 times less than the oxygen concentration increase observed.

Animals↗