Regulating size of silver nanoparticles on calcium carbonate via ultrasonic spray for effective antibacterial efficacy and sustained release.

Calcium carbonate is used as bone-filling material due to its good biocompatibility, bioactivity, and bioabsorbability, but the prevalence of infectious complications associated with calcium carbonate has created a persisting challenge in the treatment of bone defect. Therefore, this greatly necessitate the need to endow calcium carbonate with antibacterial properties. In this study, calcium carbonate powders loaded with silver nanoparticles (Ag-CaCO3) were prepared in attempt to serve as a novel antibacterial inorganic filler material. This objective was achieved using ultrasonic spray-pyrolysis (USSP) route to produce Ag-CaCO3 with 1, 5 and 10 mol% silver. The size of silver nanoparticles on CaCO3 microspheres could be regulated by adjusting silver concentration to facilitate effective release of Ag+ ions. This was demonstrated in Ag-CaCO3 (1), where the lowest silver content at 1 mol% achieved the highest Ag+ ions release over 28 days. This in turn gave rise to effective antibacterial efficiency against Staphylococcus aureus and Escherichia coli. Furthermore, CaCO3 (1) could also support osteoblast-like cells (MG-63) at a cell viability of 80%. Overall, this work extends the capabilities in employing USSP to produce inorganic filler materials with sustained antibacterial properties, bringing one step closer to the development of antibacterial products.

Percutaneous radiofrequency ablation of painful spinal tumors adjacent to the spinal cord with real-time monitoring of spinal canal temperature: a prospective study.

PURPOSE: To prospectively evaluate the feasibility, safety, and clinical utility of bone radiofrequency (RF) ablation with real-time monitoring of the spinal canal temperature for the treatment of spinal tumors adjacent to the spinal cord. MATERIALS AND METHODS: Our Institutional Review Board approved this study. Patients gave informed consent. The inclusion criteria were (a) a painful spinal metastasis and (b) a distance of 1 cm or less between the metastasis and the spinal cord. The thermocouple was placed in the spinal canal under CT fluoroscopic guidance. When the spinal canal temperature reached 45 degrees C, RF application was immediately stopped. RF ablation was considered technically successful when the procedure was performed without major complications. Clinical success was defined as a fall in the visual analogue scale score of at least 2 points. RESULTS: Ten patients with spinal tumors measuring 3-8 cm (mean, 4.9 +/- 1.5 cm) were enrolled. The distance between the tumor and the spinal cord was 1-6 mm (mean, 2.4 +/- 1.6 mm). All procedures were judged technically successful (100%). The spinal canal temperature did not exceed 45 degrees C in 9 of the 10 patients (90%). In the remaining patient, the temperature rose to 48 degrees C, resulting in transient neural damage, although RF application was immediately stopped when the temperature reached 45 degrees C. Clinical success was achieved within 1 week in all patients (100%). CONCLUSION: Bone RF ablation with real-time monitoring of the spinal canal temperature is feasible, safe, and clinically useful for the treatment of painful spinal metastases adjacent to the spinal cord.

Effects of barium concentration on the radiopacity and biomechanics of bone cement: experimental study.

PURPOSE: This study was undertaken to evaluate the changes in the radiopacity and mechanics of polymethylmethacrylate (PMMA) bone cement with the addition of barium. MATERIALS AND METHODS: Barium sulfate powder was added to a PMMA bone cement with an initial 10% barium concentration. The changes in radiopacity and strength were evaluated by testing cement blocks containing four barium concentrations (10%, 20%, 30%, 40%). Radiopacity was evaluated by measuring the computed tomography (CT) values of the bone cement, and strength was evaluated by compressive, three-point bending, and impact load tests. RESULTS: CT values increased in proportion to the barium concentration. The compressive load test showed that cement with a 40% barium concentration was significantly more fragile than cement with lower barium concentrations. The three-point bending load test showed that the cement became more fragile in proportion to the barium concentration. The impact load test showed that cement with 30% and 40% barium concentrations was significantly more fragile than cement with 10% and 20% barium concentrations. CONCLUSION: Radiopacity is increased and strength is reduced by adding increasing concentrations of barium powder to bone cement. The results of the present study suggest that adding barium permits the radiopacity and strength of bone cement to be adjusted in clinical practice.

Simultaneous microwave ablation using multiple antennas in explanted bovine livers: relationship between ablative zone and antenna.

PURPOSE: Our purpose was to determine the optimal antenna spacing to achieve large ablative zones without indentations when microwave ablation is performed with simultaneous activation of two or three antennas. MATERIALS AND METHODS: Microwave ablation was performed with single-antenna activation and simultaneous activation of two or three antennas with a spacing of 1.5, 2.0, 2.5, or 3.0 cm in explanted bovine livers. Microwave energy was applied for 10 min with a power of 45 W. The shapes and sizes of the ablative zones created were recorded and compared. RESULTS: The shape of the ablative zone was ellipsoid in the axial plane (along the antenna axis) and spherical in the transverse plane (perpendicular to the antenna axis) in single-antenna ablation. The ablative zones were spherical or ellipsoid in both the axial and transverse planes in two-and three-antenna ablation with an antenna spacing of 2.0 cm or less. Indentations were observed between the ablative zones created by the antennas when the spacing was 2.5 cm or more, reducing the minimum transverse diameter. When two-or three-antenna ablation was performed with a spacing of 2.0 cm or less, the axial and minimum transverse diameters were significantly larger than in single-antenna ablation. The largest volume (almost two or three times the single-activation volume) was achieved in two-or three-antenna ablation with an antenna spacing of 2.0 cm. CONCLUSION: We found that simultaneous microwave ablation using multiple microwave antennas creates large ablative zones without indentations when multiple antennas are activated with an antenna spacing of 2.0 cm or less.

Lung radiofrequency ablation with and without bronchial occlusion: experimental study in porcine lungs.

PURPOSE: This study was undertaken to compare the thermal lesion volumes in normal pig lungs when radiofrequency (RF) ablation is performed with and without airway occlusion. MATERIALS AND METHODS: RF ablation was performed in six pigs. A straight 17-gauge internally cooled-tip electrode with a 2-cm exposed tip was inserted into the center of the lower lobe of the lung under biplane fluoroscopic guidance. In each animal, RF ablation was performed for 12 minutes with balloon occlusion of the main bronchus in one lung and without balloon occlusion in the contralateral lung. The tissue temperature around the electrode tip was measured immediately after RF application. The volumes of the thermal lesions were compared by histologic examination of the groups of lungs ablated with and without airway occlusion. RESULTS: Tissue temperature was significantly higher in the bronchial occlusion group than in the group with normal ventilation (51 degrees C +/- 7 vs. 44 degrees C +/- 2; P < .05). RF ablation with bronchial occlusion resulted in the creation of a significantly greater thermal lesion volume compared with RF ablation with normal ventilation (6,535 mm(3) +/- 1,114 vs 3,368 mm(3) +/- 676; P < .03). CONCLUSION: Prevention of ventilation in the normal swine lung via bronchial balloon occlusion during RF ablation increases the thermal ablation lesion volume, suggesting that active ventilation is a significant cause of in vivo heat loss.