Phase-contrast microtomography of thin biomaterials.

Phase-contrast microtomography, performed at the beamline ID 22 of the European Synchrotron Radiation Facility (ESRF, Grenoble, France), is demonstrated for high-resolution 3-D imaging of a hydroxyapatite sample. The technique, which relies on phase contrast imaging, gives the possibility to observe features inside samples with negligible absorption contrast. The positive results obtained suggest a possible future investigation of the influence of the distribution of pores and defects inside biomaterial coatings, on the growth of osteoblast cells.

Osteointegration of bioactive glass-coated and uncoated zirconia in osteopenic bone: an in vivo experimental study.

In elderly and osteoporotic patients an age-related loss of osteoinductivity could be the biological cause of implant failure regardless of the high quality of the implanted device. yttria stabilized tetragonal zirconia (YSTZ), either coated with the bioactive glass named RKKP bioglaze (RKKP) or uncoated, was implanted in the distal femurs of sham-operated and ovariectomized female rats. Animals were sacrificed at 30 and 60 days. Histomorphometry and microhardness tests were performed to assess osteointegration rate as well as bone quality around the implants. Significant decreases (p < 0.0005) in trabecular bone volume, BV/TV (41%), trabecular bone surface BS/TV (33%), trabecular thickness Tb.Th (20%), and trabecular number Tb.N (32%), together with a significant increase in trabecular separation Tb.Sp (184%), were found for the osteopenic rats compared with the sham-operated rats. At both experimental times the RKKP coating ensured a better osteointegration rate with higher AI values than the uncoated YSTZ, even when osteopenic rats were used (48% at 30 days and 12% at 60 days). No differences were observed at the bone-biomaterial interfaces for either material when comparing sham-operated with osteopenic rats. The present results demonstrate that the RKKP bioactive glass used as a coating ensures a high osteointegration rate even in osteoporotic bone, which is already visible from postoperative day 30 and is still apparent on day 60.

Osteointegration of bioactive glass-coated zirconia in healthy bone: an in vivo evaluation.

Osteointegration of yttria stabilised tetragonal zirconia (YSTZ), either coated with bioactive glass named RKKP bioglaze (RKKP) or uncoated, was evaluated in an animal model. RKKP-coated and uncoated (controls) YSTZ cylinders were implanted in the distal femoral epiphyses of 14 Sprague Dawley rats under general anaesthesia. At the experimental times of 30 and 60 days after sacrifice, histomorphometry and SEM microanalysis were performed on methylmethacrylate-embedded undecalcified sections to determine the osteointegration rate. At 30 days, a significantly higher affinity index was demonstrated in vivo by histomorphometric evaluation in RKKP-coated versus uncoated YSTZ implants p < 0.05); at 60 days, the coated implants behaved better than controls (affinity index of + 32%), but the difference observed lay within the statistical uncertainty. SEM analysis demonstrated better bone adhesion to the material in RKKP-coated YSTZ at both 30 and 60 days. These findings suggest that YSTZ coated with the bioactive glass named RKKP enhances osteointegration of ceramics.

Improvement in zirconia osseointegration by means of a biological glass coating: An in vitro and in vivo investigation.

The biocompatibility and osseointegration of zirconia (ZrO(2)), either coated with RKKP bioglazeor uncoated, were evaluated in vitro and in vivo. The in vitro test was performed in human osteoblasts, whereas maximal sensitization was performed in 23 Dunkin Hurtley guinea pigs. RKKP bioglaze-coated and uncoated (controls) ZrO(2) cylinders were implanted in the distal femoral epiphyses of 14 Sprague-Dawley rats under general anesthesia, and animals were sacrificed at 30 and 60 days. Lactate dehydrogenase, alkaline phosphatase, and Thiazolyl Blue (MTT) were tested in vitro. A graded score was used for evaluating the results of the sensitization test. Histomorphometry and microhardness testing were performed to quantify the osseointegration rate, as well as bone quality around the implants. Neither in vitro cytotoxicity nor sensitization were observed. Histomorphometry demonstrated that at 30 days, the affinity index was significantly higher in coated implants than in uncoated ones (p < 0.05); at 60 days, the behavior of coated implants was better than that of uncoated ones, but differences were not significant. Significant increases in bone microhardness were found at 1000 microm from the interface area for both uncoated (p < 0.0005) and RKKP bioglaze-coated (p < 0.0005) ZrO(2), and also within 200 microm from the interface (p = 0.014) but only for coated ZrO(2.) These results suggest that RKKP bioglaze-coated ZrO(2) permits biocompatible devices with improved osseointegration properties to be manufactured.

Membrane fluidization by animycotic bifonazole.

Calorimetry, nuclear magnetic resonance and X-ray diffraction techniques have been used to obtain thermodynamic and structural information on dipalmitoyl phosphatidylcholine (DPPC) liposomes doped by the antimycotic drug bifonazole in the range 0 < R < 1, where R = moles of bifonazole/moles of DPPC. The technique of spin labeling electron spin resonance (ESR) has also been used to study permeability and fluidity properties. The decrease of the cooperativity at the gel to liquid crystalline phase transition, as shown by ESR an DSC measurements, indicates that bifonazole imparts higher fluidity to the lipid matrix. Increase in permeability of ascorbate ions, after incorporation of bifonazole in the membrane, has been detected by ESR experiments using spin label 5-SASL. 13C NMR spectra indicate that the drug molecule is highly immobilized. X-ray diffraction and freeze fracture TEM results show that the equilibrated phase at room temperature is lamellar and unidimensional together with the presence of small particles and pits of uniform size. A marked hysteresis is evident in the formation of this phase.

The freezing and thawing of water in poultry meat and vegetables irradiated by electrons at doses of 0.1-4 kGy.

Poultry meat and some vegetables, irradiated by 5 MeV electrons (0.1-4 kGy), were analysed by differential scanning calorimetry, from 24 h after irradiation. The temperature and enthalpy transitions of the water contained in the irradiated samples were measured and compared with those of unirradiated samples. We analysed 18 meat and 10 vegetable samples for each irradiation dose together with a similar number of unirradiated controls. The mean supercooling temperatures of water in the irradiated poultry meat samples and in some vegetables are significantly lower than those of controls. Moreover, the freezing enthalpies of the irradiated poultry breast are significantly lower than those of controls, while they are unchanged in the other cases. The mean ice melting temperatures and enthalpies are similar for all samples. The amount of the lowering of the water-ice transition depends on the nature of the sample and is highest in poultry breast and lowest in vegetables.