Surface enrichment of biomimetic apatites with biologically-active ions Mg2+ and Sr2+: A preamble to the activation of bone repair materials

The surface activation of calcium phosphate-based biomaterials for bone repair is an emerging route for improving bone regeneration processes. One way for such activation is through the exchange of surface calcium ions with biologically-active cations such as Mg2+ or Sr2+. In this work, the interactions of noncarbonated and carbonated nanocrystalline apatites with Mg2+ and Sr2+ were investigated by means of ion exchange experiments in solution. Langmuir-type isotherms were determined. For both Sr and Mg, a greater uptake was observed on the carbonated sample, and on both types of apatites the maximum strontium uptake was greater than that of magnesium. Inverse exchanges showed that the proportion of reversibly fixed ions after surface exchange was close to 85% for Mg and 75–80% for Sr. The results are related to the presence of a surface hydrated layer on the nanocrystals and possible exchange mechanisms are discussed. Our results favor the hypothesis of hetero-ionic surface exchanges (Mg2+↔Ca2+, Sr2+↔Ca2+) within the hydrated layer, and some analogy with octacalcium phosphate (OCP) is considered. This work should prove helpful for the control and understanding of the activation of synthetic apatite-based powders or scaffolds with bioactive elements, as well as for the global understanding of biomineralization processes

Enhanced acetylene emission near the north pole of jupiter

We report observations of acetylene emission lines near 13.3 [mu]m on Jupiter recorded at the NASA Infrared Telescope Facility in July 1984. A strong enhancement in the intensity of R10 line of the [nu]5 band was recorded within a well-localized region coincident with the southern extension of footprint of the Io magnetic lines and with previous observations of localized enhanced emission of CH4 lines. The line intensity was fairly constant outside this "bright spot." Moreover, weak lines of the hot bands 2[nu]5 - [nu]5, and ([nu]4 + [nu]5) - [nu]5 were observed within the bright spot. From the field of view and the precision of the pointing, the zone of activity of the bright spot is found to be: latitude = 59 +/- 10[deg] and longitude = 178 +/- 10[deg] (System III, 1965). The location of the spot was found to be constant over a 3-day period. Two interpretations are proposed to explain these observations: (1) a variation of the C2H2 abundance and (2) an alteration of the thermal profile in the bright spot. Either may result from precipitation of charged particles near and below the Jovian homopause.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26158/1/0000235.pd

Neurotensin type 1 receptor-mediated activation of krox24, c-fos and Elk-1: preventing effect of the neurotensin antagonists SR 48692 and SR 142948

AbstractStimulation of neurotensin (NT) type 1 receptors (NT1-R) in transfected CHO cells is followed by the activation of mitogen-activated protein kinases and the expression of the early response gene krox24. By making point mutations and internal deletions in the krox24 promoter, we show that proximal serum responsive elements (SRE) are involved in transcriptional activation by NT. In addition, we show that the related early response gene c-fos and the Ets protein Elk-1 are also induced by NT. The involvement of NT1-R in NT-mediated activation of krox24, c-fos and Elk-1 was demonstrated by the preventing effect of the specific antagonists SR 48692 and SR 142948. Finally, we show that the activation of krox24 and Elk-1 on the one hand, and that of c-fos on the other hand, result from independent transduction pathways since the former are pertussis toxin-sensitive whereas the latter is insensitive to pertussis toxin

Atmospherical simulations of the OMEGA/MEX observations

International audienc

Atmospherical simulations of the OMEGA/MEX observations

International audienc

Atmospherical simulations of the OMEGA/MEX observations

International audienc

Mars atmosphere studies with the OMEGA/Mars Express experiment: I. Overview and detection of lfuorescent emission by CO2

International audienc

Mars atmosphere studies with the OMEGA/Mars Express experiment: I. Overview and detection of lfuorescent emission by CO2

International audienc

Observations of CO on Mars with OMEGA/Mars Express: A Study of Local Variations over the Volcanoes

International audienc