[Show abstract][Hide abstract] ABSTRACT: Introduction. Animal models of urinary incontinence and erectile dysfunction following radical prostatectomy (RP) are lacking.
Aims. To develop an animal model of combined post-RP urethral sphincter and erectile dysfunctions, and noninvasive methods to assess erectile function (EF) and urinary sphincter function (USF) during prolonged follow-up.
Methods. In the main experiments, 60 male Sprague Dawley rats were randomized to a sham operation (N = 30) or electrocautery of both sides of the striated urethral sphincter (N = 30). EF and USF were evaluated preoperatively and on postoperative days 7, 15, 30, 60, and 90. Sphincter and penile tissue samples were evaluated histologically on days 7 (N = 10) and 30 (N = 10) to detect apoptosis (TUNEL assays) and fibrosis (Trichrome Masson staining).
Main Outcome Measures. To assess EF, we measured systemic and penile blood flow using penile laser Doppler and penile rigidity using a durometer before and after apomorphine injection. USF was assessed based on the retrograde leak point pressure (LPPr).
Results. Apomorphine increased baseline Doppler flow by 180% (95% confidence interval, 156–202%) and penile hardness from 3.49 ± 0.5 to 7.16 ± 0.82 Shore A units but did not change systemic arterial flow. Mean LPPr was 76.8 ± 6.18 mm Hg at baseline and decreased by 50% after injury, with no response to apomorphine on day 7. EF and USF impairments persisted up to 90 days post injury. Histology showed penile apoptosis on day 7 and extensive urethral sphincter and penile fibrosis on day 30.
Our data did not allow us to determine whether the impairment in erectile response to apomorphine preponderantly reflected arterial penile insufficiency or veno-occlusive dysfunction.
Conclusion. Electrocautery of the striated urethral sphincter caused severe and lasting impairment of EF and USF that could be monitored repeatedly using minimally invasive methods. This new animal model may hold potential for developing new treatments designed to correct post-RP impairments. Khodari M, Souktani R, Le Coz O, Bedretdinova D, Figeac F, Acquistapace A, Lesault PF, Cognet J, Rodriguez AM, and Yiou R. Monitoring of erectile and urethral sphincter dysfunctions in a rat model mimicking radical prostatectomy damage. J Sex Med 2012;9:2827–2837.
Preview · Article · Aug 2012 · Journal of Sexual Medicine
[Show abstract][Hide abstract] ABSTRACT: Regenerative cell therapy offers potential applications in many diseases involving cell loss. However, following myocardial infarction and the dramatic decrease in the number of cardiomyocytes, the injection of stem cells led to a poor and transient improvement of cardiac function. Therefore stem cell-based therapy to treat myocardial infarction requires a better understanding of the mechanisms brought into play by stem cells in heart regeneration. Among the different hypothesis raised, cell fusion between stem cells and cardiomyocytes has been described in several studies. However, the respective physiological impact of cell fusion remains unknown. During my thesis, I investigated this cell fusion mechanism in vitro in a coculture model between human multipotent adipose-derived stem cells (hMADS) and murine fully differentiated cardiomyocytes. We showed intercellular exchanges of cytoplasmic and nuclear material between both cell types, followed by a heterologous cell fusion process promoting cardiomyocyte reprogramming back to a progenitor-like state. The resulting hybrid cells expressed early cardiac commitment and proliferation markers and exhibited a mouse genotype. We provided evidence that cardiac hybrid cells were preferentially generated through partial cell fusion mediated by intercellular structures composed of f-actin and microtubule filaments. Furthermore, we showed that stem cell mitochondria were transferred into cardiomyocytes and were required for somatic cell reprogramming. In conclusion, by providing new insights into previously reported cell fusion processes, our results might contribute to a better understanding of stem cell-mediated regenerative mechanisms and thus, the development of more efficient stem cell-based heart therapies
[Show abstract][Hide abstract] ABSTRACT: Because stem cells are often found to improve repair tissue including heart without evidence of engraftment or differentiation, mechanisms underlying wound healing are still elusive. Several studies have reported that stem cells can fuse with cardiomyocytes either by permanent or partial cell fusion processes. However, the respective physiological impact of these two processes remains unknown in part because of the lack of knowledge of the resulting hybrid cells. To further characterize cell fusion, we cocultured mouse fully differentiated cardiomyocytes with human multipotent adipose-derived stem (hMADS) cells as a model of adult stem cells. We found that heterologous cell fusion promoted cardiomyocyte reprogramming back to a progenitor-like state. The resulting hybrid cells expressed early cardiac commitment and proliferation markers such as GATA-4, myocyte enhancer factor 2C, Nkx2.5, and Ki67 and exhibited a mouse genotype. Interestingly, human bone marrow-derived stem cells shared similar reprogramming properties than hMADS cells but not human fibroblasts, which suggests that these features might be common to multipotent cells. Furthermore, cardiac hybrid cells were preferentially generated by partial rather than permanent cell fusion and that intercellular structures composed of f-actin and microtubule filaments were involved in the process. Finally, we showed that stem cell mitochondria were transferred into cardiomyocytes, persisted in hybrids and were required for somatic cell reprogramming. In conclusion, by providing new insights into previously reported cell fusion processes, our data might contribute to a better understanding of stem cell-mediated regenerative mechanisms and thus, the development of more efficient stem cell-based heart therapies.
[Show abstract][Hide abstract] ABSTRACT: The response of insect olfactory receptor neurons (ORNs) to odorants involves the opening of Ca(2+)-permeable channels, generating an increase in intracellular Ca(2+) concentration. Here, we studied the downstream effect of this Ca(2+) rise in cultured ORNs of the moth Spodoptera littoralis. Intracellular dialysis of Ca(2+) from the patch pipette in whole-cell patch-clamp configuration activated a conductance with a K(1/2) of 2.8 microm. Intracellular and extracellular anionic and cationic substitutions demonstrated that Cl(-) carries this current. The anion permeability sequence I(-) > NO(3)(-) > Br(-) > Cl(-) > CH(3)SO(3)(-) > gluconate(-) of the Ca(2+)-activated Cl(-) channel suggests a weak electrical field pore of the channel. The Ca(2+)-activated current partly inactivated over time and did not depend on protein kinase C (PKC) and CaMKII activity or on calmodulin. Application of Cl(-) channel blockers, flufenamic acid, 5-nitro-2-(3-phenylpropylamino) benzoic acid, or niflumic acid reversibly blocked the Ca(2+)-activated current. In addition, lowering Cl(-) concentration in the sensillar lymph bathing the ORN outer dendrites caused a significant delay in pheromone response termination in vivo. The present work identifies a new Cl(-) conductance activated by Ca(2+) in insect ORNs presumably required for ORN repolarization.
Preview · Article · May 2010 · The Journal of Neuroscience : The Official Journal of the Society for Neuroscience
[Show abstract][Hide abstract] ABSTRACT: The role of Ca2+ in insect olfactory transduction was studied in the moth Spodoptera littoralis. Single sensillum recordings were made to investigate in vivo the role of sensillar Ca2+ on the electrophysiological properties of sex pheromone responsive olfactory receptor neurons (ORNs). Lowering the sensillar
Ca2+ concentration to 2 × 10−8 M increased ORN spontaneous firing activity and induced long bursts of action potentials (APs) superimposed on spontaneous
negative deflections of the transepithelial potential. We inferred that Ca2+ stabilizes the membrane potential of ORNs, keeping the spontaneous firing activity at a low and regular level. Neither the
amplitude and kinetics of the rising phase of sensillar potentials (SPs) recorded in response to pheromone stimuli nor the
AP generation during stimulation depended on the extracellular Ca2+ concentration. Thus, extracellular Ca2+ is not absolutely necessary for ORN response. Partial inhibition of responses with a calmodulin antagonist, W-7, also indicates
that intracellular Ca2+ contributes to the ORN response and suggests that Ca2+ release from internal stores is involved. In 2 × 10−8 M Ca2+, the repolarization of the SP was delayed when compared with higher Ca2+ concentrations. Therefore, in contrast to depolarization, ORN repolarization depends on extracellular Ca2+. Ca2+-gated K+ channels identified from cultured ORNs with whole-cell recordings are good candidates to mediate ORN repolarization.