Compression coil provides increased lead control in extraction procedures.

AIMS: We investigated a new lead extraction tool (Compression Coil; One-Tie, Cook Medical) in an experimental traction force study. METHODS AND RESULTS: On 13 pacemaker leads (Setrox JS53, Biotronik) traction force testing was performed under different configurations. The leads were assigned to three groups: (i) traction force testing without central locking stylet support (n = 5), (ii) traction force testing with the use of a locking stylet (Liberator, Cook Medical) and a proximal ligation suture (n = 4), (iii) traction force testing with the use of a locking stylet and a compression coil (n = 4). The following parameters were obtained for all groups: stress-strain curves, maximal forces, elastic modulus, post-testing lead length and lead elongation. In Groups 2 and 3 retraction of the locking stylet within the lead was measured [lead tip-locking stylet distance (LTLSD)]. Maximal forces for the three groups were: (i) 28.3 ± 0.3 N; (ii) 30.6 ± 3.0 N; (iii) 31.6 ± 2.9 N (1 vs. 2, P = 0.13; 1 vs. 3, P = 0.04; 2 vs. 3, P = 0.65). Elastic modulus was (i) 22.8 ± 0.1 MPa; (ii) 2830.8 ± 351.1 MPa; (iii) 2447.0 ± 510.5 MPa (1 vs. 2, P < 0.01; 1 vs. 3, P < 0.01; 2 vs. 3, P = 0.26). Mean LTLSD in Group 2 was 19.8 ± 3.2 cm and was 13.8 ± 1.7 cm in Group 3 (P = 0.02). The ratio of LTLSD/post-testing lead length was 0.37 ± 0.03 for Group 2 and 0.24 ± 0.03 for Group 3 (P < 0.01). CONCLUSION: The application of a compression coil leads to an increased lead control expressed by less retraction of the locking stylet within the lead. This enables improved central support of extraction sheaths in the case of challenging extraction procedures.

Inflammatory response of lung macrophages and epithelial cells after exposure to redox active nanoparticles: effect of solubility and antioxidant treatment.

The effects of an exposure to three mass-produced metal oxide nanoparticles-similar in size and specific surface area but different in redox activity and solubility-were studied in rat alveolar macrophages (MAC) and epithelial cells (AEC). We hypothesized that the cell response depends on the particle redox activity and solubility determining the amount of reactive oxygen species formation (ROS) and subsequent inflammatory response. MAC and AEC were exposed to different amounts of Mn3O4 (soluble, redox-active), CeO2 (insoluble, redox-active), and TiO2 (insoluble, redox-inert) up to 24 h. Viability and inflammatory response were monitored with and without coincubation of a free-radical scavenger (trolox). In MAC elevated ROS levels, decreased metabolic activity and attenuated inflammatory mediator secretion were observed in response to Mn3O4. Addition of trolox partially resolved these changes. In AEC, decreased metabolic activity and an attenuated inflammatory mediator secretion were found in response to CeO2 exposure without increased production of ROS, thus not sensitive to trolox administration. Interestingly, highly redox-active soluble particles did not provoke an inflammatory response. The data reveal that target and effector cells of the lung react in different ways to particle exposure making a prediction of the response depending on redox activity and intracellular solubility difficult.

Mussel-inspired load bearing metal-polymer glues.

A mussel-inspired synthetic adhesive based on dopamine containing methacrylate copolymers was developed to bond polymers to metal surfaces at an adhesion strength of up to 20 MPa for bulk samples.

Use of NIR light and upconversion phosphors in light-curable polymers.

OBJECTIVE: Light-curable polymers are commonly used in restorative surgery, prosthodontics and surgical procedures. Despite the fact of wide application, there are clinical problems due to limitations of blue light penetration: application is restricted to defects exposed to the light source, layered filling of defect is required. METHODS: Combining photo-activation and up conversion allows efficient polymer hardening by deep penetrating near-infrared (NIR) light. The prerequisite 450 nm blue light to polymerize dental resins could be achieved by filler particles, which absorb the incident NIR irradiation and convert it into visible light. RESULTS: The on spot generated blue light results in uniform polymer hardening. Composite samples of 5mm thickness were cured two times faster than pure polymer cured by blue light (30 and 60 s, respectively). Overall degree of monomer conversion resulted in higher values of more than 40%. The enhanced transmission of NIR light was confirmed by optical analysis of dentin and enamel. The NIR transmittance surge in the 800-1200 nm window could improve sealing of complex and deep caries lesions. SIGNIFICANCE: We demonstrate faster curing and an improved degree of polymerization by using upconversion filler particles as multiple light emission centers. This study represents an alternative approach in curing dental resins by NIR source.

Light-curable polymer/calcium phosphate nanocomposite glue for bone defect treatment.

Light-curable, methacrylate-based resins are clinically used for complex defect repair in dentistry (Heliobond). The present study investigates how such easy-to-apply polymers may be used on a much broader range of applications, particularly for gluing wet bone. We investigate the significantly improved adhesion of the polymer to wet bone surfaces in a close to in vivo setup using freshly cut cow hip bone as a model. The use of a reactive filler (20 wt.% amorphous, glassy calcium phosphate nanoparticles, a-CaP) allows for combination of the properties of the polymer (strength; light-curing) and the reactive filler (recrystallization of amorphous CaP to hydroxyapatite within minutes). This filler alone has been earlier suggested for use as an injectable bone cement since it reacts under in vivo conditions within 10-15 min. Our study transfers this reactivity into a composite, thus using the reactive CaP phase to establish an improved adhesion of the composite to wet bone surfaces. Additional in vitro bioactivity tests, compressive and tensile strength suggest use of such light-curable nanocomposites for complex-shaped load-bearing implant materials and fracture repair.