Secondary urethral sphincter function of the rabbit pelvic and perineal muscles.

Perineal and pelvic floor muscles play an important role in continence by providing mechanical support to pelvic organs. It is also known that the pubococcygeus muscle (PcM) contracts in the storage phase and is inactive during voiding, while the bulbospongiosus muscle (BsM) is active during the voiding phase. Recent evidence suggested an additional role of these muscles in supporting urethral closure in rabbits. However, the individual role of perineal and pelvic muscles as urethral sphincters is not well-defined. Here we evaluated the individual, sequential and synergistic roles of the PcM and BsM in assisting urethral closure and defined the optimal electrical stimulation parameters that can effectively contract these muscles and increase the urethral pressure (P ura ) in young nulliparous animals (n = 11). Unilateral stimulation of either the BsM or PcM at 40 Hz induced modest increases in average P ura (0.23 ± 0.10 and 0.07 ± 0.04 mmHg, respectively). Investigation on the changes in P ura evoked by stimulation frequencies between 5 and 60 Hz show that sequential contralateral PcM-BsM activation at 40 Hz induced a 2-fold average P ura increase (0.23 ± 0.07 mmHg) compared to that evoked by PcM stimulation. Simultaneous activation of PcM and BsM at 40 Hz also showed an increased average P ura (0.26 ± 0.04 mmHg), with a 2-fold increase in average P ura observed during the unilateral sequential PcM-BsM stimulation at 40 Hz (0.69 ± 0.2 mmHg). Finally, stimulation at 40 Hz of the bulbospongiosus nerve (BsN) induced an approximate 4-fold increase in average P ura (0.87 ± 0.44 mmHg; p < 0.04) compared to that elicited by BsM stimulation, confirming that direct nerve stimulation is more effective. Together, this study shows that in the female rabbit, both perineal and pelvic muscles support of the urethral function during continence, and that unilateral stimulation of the BsN at 40-60 Hz is sufficient to achieve maximal secondary sphincter activity. The results also support the potential clinical value of neuromodulation of pelvic and perineal nerves as bioelectronic therapy for stress urinary incontinence.

Investigation of the early healing response to dicationic imidazolium-based ionic liquids: a biocompatible coating for titanium implants.

Dicationic Imidazolum-based ionic liquids with amino acid anions (IonL) have been proposed as a multifunctional coating for titanium dental implants, as their properties have been shown to address multiple early complicating factors while maintaining host cell compatibility. This study aims to evaluate effects of this coating on host response in the absence of complicating oral factors during the early healing period using a subcutaneous implantation model in the rat. IonLs with the best cytocompatibility and antimicrobial properties (IonL-Phe, IonL-Met) were chosen as coatings. Three different doses were applied to cpTi disks and subcutaneously implanted into 36 male Lewis rats. Rats received 2 implants: 1 coated implant on one side and an uncoated implant on the contralateral sides (n=3 per formulation, per dose). Peri-implant tissue was evaluated 2 and 14 days after implantation with H&E staining and IHC markers associated with macrophage polarization as well as molecular analysis (qPCR) for inflammatory and healing markers. H&E stains revealed the presence of the coating, blood clots and inflammatory infiltrate at 2 days around all implants. At 14 days, inflammation had receded with more developed connective tissue with fibroblasts, blood vessels in certain doses of coated and uncoated samples with no foreign body giant cells. This study demonstrated that IonL at the appropriate concentration does not significantly interfere with and healing and Ti foreign body response. Results regarding optimal dose and formulation from this study will be applied in future studies using an oral osseointegration model.

Detection of apoptotic and live pre-osteoblast cell line using impedance-based biosensors with variable electrode design.

Electrical impedance-based sensing of cell activity has become a powerful analytical tool that allows the monitoring of several relevant biological processes associated with cell evolution and morphology. In these types of biosensors, the electrode design has a direct impact on the sensitivity because it defines the capability of the biosensor to measure small changes in the impedance resulting from cell activities. Herein, impedance-based biosensors arrays with several configurations were successfully developed and used to study the impact of the electrode layout on the dynamics of cultured pre-osteoblast cells. The biosensor design was initially validated by measuring the effect of electrode design on the capacitance of a dielectric polymer (parylene) that mimics the dielectric characteristics of cell populations, results are shown in the Supplementary information section. Results from in vitro cell growth indicate that the optimized design of single electrodes with a diameter of 50 µm, are the most sensitive to cell motion whereas increasing the number of electrodes allows clear differentiation between living and dead cells after 3 h of inducing apoptosis. Apoptosis death was induced with Staurosporine, a chemical mediator of apoptosis in osteoblasts. These impedance results have been validated with optical imaging and flow cytometry analysis that were performed on parallel cultures. Frequency and electrolyte concentration effects are also discussed.