Effects of hydroxyapatite and PDGF concentrations on osteoblast growth in a nanohydroxyapatite-polylactic acid composite for guided tissue regeneration

The technique of guided tissue regeneration (GTR) has evolved over recent years in an attempt to achieve periodontal tissue regeneration by the use of a barrier membrane. However, there are significant limitations in the currently available membranes and overall outcomes may be limited. A degradable composite material was investigated as a potential GTR membrane material. Polylactic acid (PLA) and nanohydroxyapatite (nHA) composite was analysed, its bioactive potential and suitability as a carrier system for growth factors were assessed. The effect of nHA concentrations and the addition of platelet derived growth factor (PDGF) on osteoblast proliferation and differentiation was investigated. The bioactivity was dependent on the nHA concentration in the films, with more apatite deposited on films containing higher nHA content. Osteoblasts proliferated well on samples containing low nHA content and differentiated on films with higher nHA content. The composite films were able to deliver PDGF and cell proliferation increased on samples that were pre absorbed with the growth factor. nHA–PLA composite films are able to deliver active PDGF. In addition the bioactivity and cell differentiation was higher on films containing more nHA. The use of a nHA–PLA composite material containing a high concentration of nHA may be a useful material for GTR membrane as it will not only act as a barrier, but may also be able to enhance bone regeneration by delivery of biologically active molecules

An optimized reciprocity Monte Carlo method for the calculation of radiative transfer in media of various optical thicknesses

An efficient Monte Carlo method for the calculation of radiative transfer in complex geometry systems including semi-transparent media has been achieved and validated. This method, which is based on the reciprocity principle and called optimized reciprocity method (ORM), can be applied to systems discretized in a large number of cells. For each pair of elementary cells exchanging radiative energy, the transfer calculation is carried out by minimizing, for a given computational time, the standard deviation of the radiative power or of the wall flux. The results obtained with ORM have been successfully compared to those obtained with previous approaches in a numerical benchmark

Cryogenic propellant combustion studies : experimental and analysis aspects

Communication to : Conference internationale sur la propulsion des engins spatiaux, Dublin (Ireland), May 19-20, 1998SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1998 n.99 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Comparative Study of Hydroxyapatite Prepared from Seashells and Eggshells as a Bone Graft Material

The aims of this study were to determine the physical properties of hydroxyapatite from seashells (sHA) and from eggshells (eHA), to analyze elements within sHA and eHA, and to compare the bone regeneration ability between sHA and eHA in a rat parietal bone defect model. The sHA and eHA particles had a similar morphology in scanning electron microscope images. From the Fourier-transform infrared absorbance spectra and X-ray diffraction results, both types of hydroxyapatite (HA) had the characteristics of pure HA. Inductively coupled plasma atomic emission spectroscopy results suggested that the sHA had higher levels of sodium and strontium than the eHA, whereas the eHA had higher levels of magnesium than the sHA. In μ-CT results, the mean bone mineral density of the sHA was significantly higher than the control at 4 weeks after the operation (p = 0.012). The mean bone volume of the eHA was significantly higher than the control at 8 weeks after the operation (p = 0.012). In the histological images at 4 weeks after the operation, foreign body multinucleated giant cells were observed around the agglomerated sHA particles, while there were fewer inflammatory reactions around the agglomerated eHA particles. The eHA group showed better results in bone formation than did the sHA group in this study

Fístula carótido-cavernosa com epistaxe letal: relato de caso Carotid-cavernous fistula with lethal epistaxis: case report

A fístula carótido-cavernosa é uma comunicação patológica entre a artéria carótida interna e o seio cavernoso. Apresentamos o caso de um paciente de 32 anos de idade com fístula carótido-cavernosa devida a traumatismo crânio-encefálico. O tratamento preconizado é a embolização mas neste caso em especial houve falha devido às características próprias da fístula, e o paciente progrediu de maneira desfavorável evoluindo ao óbito por epistaxe incontrolável.<br>We report the case of a 32 years old male patient with carotid-cavernous fistula caused by head injury who died from massive epistaxis. Treatment assesment of this case is faced with the literature

On the use of Plasma Synthetic Jets for the control of jet flow and noise

International audienceThe noise generated by an isothermal single stream jet at Mach number Mj = 0.9 and diameter-based Reynolds number ReD = 1e6 is investigated numerically for an unforced confi guration and a forced confi guration with an active control device. This active flow forcing is performed with 12 Plasma Synthetic Jets (PSJs) located at the nozzle lip and acting on the axisymmetric mode of the shear layer of the main jet with a forcing Strouhal number StF of 0.14. Simulated flow and noise results are validated with comparisons to available experiments performed for identical jet conditions. The noise radiation of the reference, unforced jet is globally well recovered numerically with a limited overestimation of the experimental pressure levels, below 3 dB for most of the observations angles. In the presence of the control, the simulated interaction between the fluid injected by the PSJs and the main flow reproduces very well the development of a large coherent vortex observed experimentally in the jet shear layer. The control is also found to favour the generation of turbulence. It translates for the acoustics to an increase of the broadband noise and of the integrated pressure levels of 1.5 dB in both experiments and simulations