The application of bioactive ceramic coatings to prostheses confers strength to a material (ceramic or biological glass) that exerts beneficial effects on bone-tissue growth but that itself lacks the ...toughness and stability required of an implant device. The rate of bioactivity is related to the chemical reactivity of the material and causes interface dissolution, precipitation and ion-exchange reactions. Ceramics may differ in sintering temperature and thus exhibit differences in their in vitro dissolution features and in vivo performance. To test these effects, in vitro and in vivo studies were carried out on two biocompatible biological glasses and a ceramic of proven bioactivity in view of their potential utilization as covering materials. In addition, a modified chitosan was adsorbed on the surface of a series of hydroxyapatite (HA) samples. Human fibroblasts and/or osteoblasts were used for the in vitro tests, and normal (INT) and osteoporotic (OVX) rats, normal rabbits and sheep for the in vivo studies. Similar chemical changes were observed in both glasses, suggesting that these materials underwent modifications directly dependent on their biological environment. The in vivo tests point to the possibility of improving the bioactivity of ceramic substrates with chitosan. However, the different behaviour of the materials in vitro and in vivo suggests that these tests should be conducted in parallel.
Some proximal femur geometry (PFG) parameters, measured by dual-energy X-ray absorptiometry (DXA), have been reported to discriminate subjects with hip fracture. Relatively few studies have tested ...their ability to discriminate femoral neck fractures from those of the trochanter. To this end we performed a cross-sectional study in a population of 547 menopausal women over 69 years of age with femoral neck fractures (n = 88), trochanteric fractures (n = 93) or controls (n = 366). Hip axis length (HAL), neck-shaft angle (NSA), femoral neck diameter (FND) and femoral shaft diameter (FSD) were measured by DXA, as well as the bone mineral density (BMD) of the nonfractured hip at the femoral neck, trochanter and Ward's triangle. In fractured subjects, BMD was lower at each measurement site. HAL was longer and NSA wider in those with femoral neck fractures. With logistic regression the age-adjusted odds ratio (OR) for a 1 standard deviation (SD) decrease in BMD was significantly associated at each measurement site with femoral neck fracture (femoral neck BMD: OR 1.9, 95% confidence interval (95% CI): 1.4-2.5; trochanter BMD: OR 1.6, 95% CI 1.2-2.0; Ward's triangle BMD: OR 1.7, 95% CI 1.3-2.2) and trochanteric fracture (femoral neck BMD: OR 2.6, 95% CI 1.9-3.6; trochanter BMD: OR 3.0, 95% CI 2.2-4.1; Ward's triangle BMD: OR 1.8, 95% CI 1.4-2.3). Age-adjusted OR for 1 SD increases in NSA (OR 2.2, 95% CI 1.7-2.8) and HAL (OR 1.3, 95% CI 1.1-1.6) was significantly associated with the fracture risk only for femoral neck fracture. In the best predictive model the strongest predictors were site-matched BMD for both fracture types and NSA for neck fracture. Trochanteric BMD had the greatest area (0.78, standard error (SE) 0.02) under the receiver operating characteristic curve in trochanteric fractures, whereas for NSA (0.72, SE 0.03) this area was greatest in femoral neck fractures. These results confirm the association of BMD with proximal femur fracture and support the evidence that PFG plays a significant role only in neck fracture prediction, since NSA is the best predictive parameter among those tested.
Objectives: The purpose of this study was to evaluate endothelium-dependent flow-mediated dilation (FMD) in the brachial artery and the plasma levels of endothelin-1 in postmenopausal women at risk ...for coronary artery disease before and after treatment with both estradiol and estradiol plus dydrogesterone.
Methods: Sixteen postmenopausal women (PMW) (mean age 58±9 years) with more than two risk factors for coronary artery disease, were randomized to receive either oral estradiol (2 mg) for 28 days or oral estradiol (2 mg) for 14 days and oral estradiol (2 mg) and dydrogesterone (10 mg) for 14 days, in a double-blind, placebo-controlled, single cross-over study. Patients were crossed-over the complementary treatment 7 days after completing the first treatment. The study of forearm blood flow and the measurement of plasma endothelin-1 levels was carried out before and after each treatment.
Results: Estradiol significantly increased FMD as compared to baseline; the addition of dydrogesterone did not affect the effect of estradiol on FMD. Similarly reactive hyperemic flow increased after estradiol alone or in association with dydrogesterone compared to baseline. Plasma levels of endothelin-1 were significantly reduced by estradiol both when administered alone or in association with dydrogesterone.
Conclusions: Hormone replacement therapy with estradiol and dydrogesterone improves endothelial function and reduces plasma levels of endothelin-1 in PMW at risk for coronary artery disease.
The aim of the study reported here was to provide some basic and general information on the suitability of an experimental sheep model for conducting in vivo orthopedic studies. The authors have ...classified the fundamental aspects that should be carefully evaluated when using sheep as
an experimental model in orthopedic research: factors strictly related to bone anatomy and formation; and factors strictly affecting bone physiology, such as gastrointestinal mineral and vitamin absorption, and reproductive cycle. Future investigations should address all of the aspects highlighted,
since there is no animal with the same anatomic, biochemical, physiologic, and biological characteristics as those of human beings. Moreover, useful data for treating orthopedic patients are based not only on good planning and study design, but also on perfect knowledge of the animal used
and the differences between the model and the human being. The authors hope that this report will contribute to extrapolation of reliable data for use of sheep in the orthopedics field.
Aims Patients with cardiovascular diseases frequently complain of erectile dysfunction especially when treated with beta-blockers. In order to assess whether the effect of beta-blockers on erectile ...dysfunction is in part related to patient knowledge of the drug side effects, 96 patients (all males, age 52±7 years) with newly diagnosed cardiovascular disease and not suffering from erectile dysfunction entered a two phase, single cross over study. Methods and results During the first phase of the study patients received atenolol 50mg o.d. (A), 32 patients were blinded on the drug given (group A), 32 were informed on the drug given but not on its side effects (group B) and 32 took A after being informed on its side effects on erectile function (group C). After 3 months the incidence of erectile dysfunction was 3.1% in the group A, 15.6% in group B and 31.2% in group C (P<0.01). All patients reporting ED entered the second phase of the study and were randomised to receive Sildenafil 50mg and placebo in a cross over study. Sildenafil citrate and placebo were equally effective in reversing erectile dysfunction in all but one patient reporting ED with Atenolol. Conclusion Our results show that the knowledge and prejudice about side effects of beta-blockers can produce anxiety, that may cause erectile function.
As the only directly imaged multiple planet system, HR 8799 provides a unique opportunity to study the physical properties of several planets in parallel. In this paper, we image all four of the HR ...8799 planets at H band and 3.3 mu m with the new Large Binocular Telescope adaptive optics system, PISCES, and LBTI/LMIRCam. Our images offer an unprecedented view of the system, allowing us to obtain H and 3.3 mu m photometry of the innermost planet (for the first time) and put strong upper limits on the presence of a hypothetical fifth companion. We find that all four planets are unexpectedly bright at 3.3 mu m compared to the equilibrium chemistry models used for field brown dwarfs, which predict that planets should be faint at 3.3 mu m due to CH sub(4) opacity. We attempt to model the planets with thick-cloudy, non-equilibrium chemistry atmospheres but find that removing CH sub(4) to fit the 3.3 mu m photometry increases the predicted L' (3.8 mu m) flux enough that it is inconsistent with observations. In an effort to fit the spectral energy distribution of the HR 8799 planets, we construct mixtures of cloudy atmospheres, which are intended to represent planets covered by clouds of varying opacity. In this scenario, regions with low opacity look hot and bright, while regions with high opacity look faint, similar to the patchy cloud structures on Jupiter and L/T transition brown dwarfs. Our mixed-cloud models reproduce all of the available data, but self-consistent models are still necessary to demonstrate their viability.
PDF
