Decrease In Leak Point Pressure Research Articles

Contribution of pudendal nerve injury to stress urinary incontinence in a male rat model

Urinary incontinence is a common complication following radical prostatectomy, as the surgery disturbs critical anatomical structures. This study explored how pudendal nerve (PN) injury affects urinary continence in male rats. In an acute study, leak point pressure (LPP) and external urethral sphincter electromyography (EMG) were performed on six male rats with an intact urethra, the urethra exposed (UE), the PN exposed (NE), and after PN transection (PNT). In a chronic study, LPP and EMG were tested in 67 rats 4 days, 3 weeks, or 6 weeks after sham PN injury, PN crush (PNC), or PNT. Urethras were assessed histologically. Acute PNT caused a significant decrease in LPP and EMG amplitude and firing rate compared to other groups. PNC resulted in a significant reduction in LPP and EMG firing rate 4 days, 3 weeks, and 6 weeks later. EMG amplitude was also significantly reduced 4 days and 6 weeks after PNC. Neuromuscular junctions were less organized and less innervated after PNC or PNT at all timepoints compared to sham injured animals. Collagen infiltration was significantly increased after PNC and PNT compared to sham at all timepoints. This rat model could facilitate preclinical testing of neuroregenerative therapies for post-prostatectomy incontinence.

An evidence-based approach to the recovery of bladder and bowel function after pediatric spinal cord injury

IntroductionBladder dysfunction and associated complications of the urinary system negatively impact the quality of life in children living with spinal cord injury (SCI). Pediatric lower urinary tract deficits include bladder over-activity, inefficient emptying, decreased compliance, and incontinence. Recent evidence in adults with SCI indicates significant improvements in bladder capacity and detrusor pressure following participation in an activity-based recovery locomotor training (ABR-LT) rehabilitative program. Additionally, anecdotal self-reports from parents in our Pediatric NeuroRecovery Program reference changes in bladder function, ranging from awareness of bladder fullness to gains in voluntary control while undergoing ABR-LT. Case presentationIn a within-subjects repeated measures study, we investigated the effect of ABR-LT on bladder function in three children (ages: 2.5, 3, and 6 years) who sustained upper motor neuron SCI. Each child received at least 60 sessions of ABR-LT (5x/week) for 12–14 weeks. Bladder function was assessed via urodynamics and the Common Data Elements questionnaires. Awareness of bladder filling during cystometry was present in all children and detrusor leak point pressure (LPP) was reduced post-ABR-LT relative to pre-training. A decrease in LPP after locomotor training was observed in all three participants. One out of the three participants had substantial improvements in bladder capacity post-ABR-LT and experienced less bowel incontinence following training. DiscussionLike our evidence in adults, the changes in bladder function suggest an interaction between lumbosacral networks regulating spinal reflex control of bladder filling, voiding, and afferent input (including potential descending supraspinal commands) and those activated by ABR-LT. Locomotor training may be associated with increased bladder capacity, enhanced perception of bladder filling, and decreased LPP as well as improvements in bowel control in pediatric SCI. This research suggests that children and adolescents with traumatic SCI could experience dynamic improvements in bladder and bowel function with the aid of various therapies. Studies assessing the durability of training on the recovery of bladder and bowel dysfunction in children with SCI are needed.

Urethral injection of dedifferentiated fat cells ameliorates sphincter damage and voiding dysfunction in a rat model of persistence stress urinary incontinence

PurposeDedifferentiated fat (DFAT) cells are mature adipocyte-derived multipotent cells that can be applicable to cell-based therapy for stress urinary incontinence (SUI). This study developed a persistence SUI model that allows long-term evaluation using a combination of vaginal distention (VD) and bilateral ovariectomy (OVX) in rats. Then, the therapeutic effects of DFAT cell transplantation in the persistence SUI model was examined.MethodsIn total, 48 Sprague–Dawley rats were divided into four groups and underwent VD (VD group), bilateral OVX (OVX group), VD and bilateral OVX (VD + OVX group), or sham operation (Control group). At 2, 4, and 6 weeks after injury, leak point pressure (LPP) and histological changes of the urethral sphincter were evaluated. Next, 14 rats undergoing VD and bilateral OVX were divided into two groups and administered urethral injection of DFAT cells (DFAT group) or fibroblasts (Fibroblast group). At 6 weeks after the injection, LPP and histology of the urethral sphincter were evaluated.ResultsThe VD + OVX group retained a decrease in LPP with sphincter muscle atrophy at least until 6 weeks after injury. The LPP and urethral sphincter muscle atrophy in the DFAT group recovered better than those in the fibroblast group.ConclusionsThe persistence SUI model was created by a combination of VD and bilateral OVX in rats. Urethral injection of DFAT cells inhibited sphincter muscle atrophy and improved LPP in the persistence SUI model. These findings suggest that the DFAT cells may be an attractive cell source for cell-based therapy to treat SUI.

The vaginal distention model in mice is not a reliable model of simulated birth trauma-induced stress urinary incontinence.

Vaginal distention (VD) is a validated model of birth-related trauma in rats. Recently a mouse VD model was reported. Our study was originally conducted to evaluate the impact of age on VD in mice. This manuscript describes the study and reports on the lack of reproducibility of VD models in mice. We utilized female C57BL/6 mice. A total of 190, 12-weeks old mice, were randomized into VD and sham groups. We inflated a modified Foley's balloon with 0.3 mL for 1 h inside the mice vagina. Afterwards, we measured the leak point pressure (LPP) at defined timepoints (0, 4, 10, 20, or 40 days). We randomized another 190, 40-week old, C57BL/6 mice into either VD or sham groups. We used an extra 20 mice as age - matched controls. In both 12 and 40 weeks-old mice, LPP was significantly decreased versus the negative controls at day 0. Additionally, in both 12 and 40 weeks-old mice, the decrease in LPP was significantly higher in the VD group compared to the sham group at day 0. However, the LPP results were comparable between VD and sham at any other time point thereafter. Furthermore, there was no significant change in LPP values between instrumented (VD and sham) mice and control mice at any time after day 0. The VD models previously described is not a reproducible model for the study of VD with large number of mice. Our results, unfortunately, do not support its use to study VD injury in mice.

Effects of multiple simulated birth traumas on urethral continence function in rats.

Multiple vaginal parities have been reported to be an important risk factor for stress urinary incontinence (SUI). Simulated birth trauma with single vaginal distention (VD) has been used to induce the SUI condition in animals; however, the effect of multiple simulated birth traumas on the urethral continence function has not been well characterized. Therefore, we examined the effects of multiple VDs on urethral functions in vivo and the changes in gene expressions of several molecules in the urethra using female SD rats, which were divided into three groups; sham, VD-1 (single VD), and VD-3 groups (3 times of VDs every 2 wk). Two weeks after the final VD, leak point pressure (LPP) and urethral responses during sneezing were evaluated. Also, changes in mRNA levels of urethral molecules were quantified with RT-PCR. The VD-1 group did not show any change in LPP with only a tendency of decrease in amplitudes of the urethral responses during sneezing (A-URS); however, the VD-3 group showed a significant decrease in LPP and urethral responses such as baseline urethral pressure and A-URS accompanied with SUI episodes during sneezing. Nicotinic receptor subtypes and transforming growth factor (TGF)-β1 were significantly increased in both VD-1 and VD-3 groups while TNF receptor (TNFR)-1, IL-6, collagens, and matrix metalloproteinases-9 were significantly increased only in the VD-3 group. These data indicate that rats with multiple simulated birth traumas exhibit profound impairment of the urethral continence function and that these functional changes are associated with those in cytokines, extracellular matrix molecules, and nicotinic receptor subtypes in the urethra.

Autologous Bone Marrow-Derived Cells Regenerate Urethral Sphincters.

Regenerative medicine based on tissue engineering and/or stem cell therapy techniques has the potential to improve irreversibly damaged tissues. Surgical injury to the lower urinary tract can occur as a result of radical prostatectomy or bladder neck surgery. Regeneration of urethral sphincters could be an effective treatment for post-surgical intrinsic sphincter deficiency (ISD)-related urinary incontinence. The replacement, enhancement, and/or recovery the urethral sphincter striated and smooth muscles could increase urethral closure pressure to help patients regain continence. Stem cells from muscle-derived satellite or adipose-derived mesenchymal cells provide temporary improvement in urethral closure pressure but do not reconstruct the muscle layer structures. Our strategy to accomplish regeneration of urethral sphincters is the utilization of autologous bone marrow-derived cells. We have developed a freeze injury model of ISD in rabbits. Freezing of the urinary sphincter causes loss of the majority of striated and smooth muscle cells, and causes a significant decrease in leak point pressure. In this review, we show that the autologous bone marrow-derived cells implanted within the freeze-injured sphincters differentiate into striated or smooth muscle cells. These cells then develop to reconstitute muscle layer structures within the sphincter. Furthermore, the leak point pressure of cell-implanted rabbits is significantly higher than that of cell-free injected controls. We conclude that implantation of autologous bone marrow-derived cells could be an effective treatment for human post-surgical ISD-related urinary incontinence.

Development of a rabbit's urethral sphincter deficiency animal model for anatomical-functional evaluation

The aim of the study was to develop a new durable animal model (using rabbits) for anatomical-functional evaluation of urethral sphincter deficiency. A total of 40 New Zealand male rabbits, weighting 2.500 kg to 3.100 kg, were evaluated to develop an incontinent animal model. Thirty-two animals underwent urethrolysis and 8 animals received sham operation. Before and at 2, 4, 8 and 12 weeks after urethrolysis or sham operation, it was performed cystometry and leak point pressure (LPP) evaluation with different bladder distension volumes (10, 20, 30 mL). In each time point, 10 animals (8 from the study group and 2 from the sham group) were sacrificed to harvest the bladder and urethra. The samples were evaluated by H&E and Masson 's Trichrome to determine urethral morphology and collagen/smooth muscle density. Twelve weeks after urethrolysis, it was observed a significant decrease in LPP regardless the bladder volume (from 33.7 ± 6.6 to 12.8 ± 2.2 cmH₂O). The histological analysis evidenced a decrease of 22% in smooth muscle density with a proportional increase in the collagen, vessels and elastin density (p < 0.01). Transabdominal urethrolysis develops urethral sphincter insufficiency in rabbits, with significant decrease in LPP associated with decrease of smooth muscle fibers and increase of collagen density. This animal model can be used to test autologous cell therapy for stress urinary incontinence treatment.

Transplantation of mature adipocyte‐derived dedifferentiated fat (DFAT) cells improves urethral sphincter contractility in a rat model

To examine the effects of mature adipocyte-derived dedifferentiated fat (DFAT) cell transplantation on urethral tissue regeneration and sphincter function. Sixteen female Sprague-Dawley rats underwent vaginal distension (VD) for 3 h. Subsequently, green fluorescence protein (GFP)-labeled DFAT cells (1×10(6) in 20 µL saline, DFAT group, n=8) or saline (20 µL, control group, n=8) were injected into paraurethral connective tissue. Two weeks following VD, leak point pressure (LPP) was measured and an immunohistochemical analysis of the urethra was performed to evaluate urethral sphincter regeneration. The VD model was characterized by atrophy of the urethral sphincter and showed a decrease in LPP. DFAT cell transplantation resulted in a significant improvement of LPP (DFAT group: 37.3±6.4 vs control group: 21.7±5.7 mmHg, P<0.01). Immunohistochemistry revealed that the striated muscle thickness and smooth muscle α-actin-positive area were significantly (P<0.05) larger in the DFAT group than in the control group. DFAT cell transplantation enhanced macrophage accumulation followed by an increased number of cells in the proliferative state. Transplanted DFAT cells were observed in the damaged smooth muscle layer and showed positive staining for smooth muscle α-actin, suggesting conversion into the smooth muscle cell phenotype. DFAT cell transplantation promotes sphincter muscle regeneration and improves LPP in the rat VD model.

Neurogenic aspects of stress urinary incontinence

Vaginal childbirth is a significant risk factor for stress urinary incontinence (SUI). Women with SUI demonstrate dysfunction of the pelvic floor and pudendal nerve. Animal models of SUI have been developed to investigate its pathophysiology and for preclinical testing of potential treatments. Vaginal distension, a method of simulating childbirth injury in animals, produces a reliable decrease in leak point pressure (LPP), a measure of urethral resistance to leakage and quantification of SUI severity in animals. In addition to ischemia and direct tissue damage, vaginal distension causes denervation of the external urethral sphincter (EUS). Pudendal nerve crush produces a similar decrease in LPP, whereas combined PNC and vaginal distension injury delays recovery of LPP compared with either single injury alone. Neurophysiologic studies have elucidated the results of each injury and their combination on pudendal nerve and EUS function. Urethrolysis, electrocautery, and pudendal nerve transection produce more durable functional impairment via both structural damage and denervation. Pubourethral ligament injury eliminates the structural support of the urethra, but its neurologic effects are unknown. Animal models demonstrate a complex interplay between tissue damage and pudendal nerve dysfunction, and provide insight into the importance of neuroregeneration in the recovery of continence.

Voiding function in obese and type 2 diabetic female rats

The effects of obesity and type 2 diabetes (DMII) on the lower urinary tract (LUT) were characterized by evaluating voiding function and anatomy in female Zucker diabetic fatty (ZDF) rats. Age-matched female virgin rats were separated into three experimental groups: Zucker lean rats (control; normal diet, n = 22), ZDF rats (obese+nondiabetic; low-fat diet, n = 22), and ZDF rats (obese+diabetic; high-fat diet, n = 20). Rats were placed on their specified diet for 10 wk before urodynamic LUT evaluation. A suprapubic catheter was implanted 2 days before urodynamic studies. Voiding function was evaluated by cystometric and leak point pressure (LPP) testing. The bladder, urethra, and vagina were immediately excised for qualitative histological evaluation. Compared with control rats, obese+nondiabetic and obese+diabetic rats had significantly decreased contraction pressure (P = 0.003) and increased cystometric filling volume (P < 0.001). Both obese groups exhibited significantly higher voided volumes (P = 0.003), less frequent urinary events (P < 0.001), and increased residual volumes (P = 0.039). LPP studies showed a nonsignificant decrease in LPP (P = 0.075) and baseline pressure (P = 0.168) in both obese groups compared with control. Histology of the external urethral sphincter in obese rats showed increased fibrosis, leading to disruption of the skeletal muscle structure compared with control. Additionally, the bladder wall of the obese+nondiabetic and obese+diabetic rats demonstrated edema and vasculopathy. Voiding dysfunction was evident in both obese groups but with no significant differences due to DMII, suggesting that voiding dysfunction in DMII may be attributable at least in part to chronic obesity.

Lower urogenital tract anatomical and functional phenotype in lysyl oxidase like-1 knockout mice resembles female pelvic floor dysfunction in humans

Female pelvic floor dysfunction (FPFD) is a complex group of conditions that include urinary incontinence and pelvic organ prolapse (POP). In humans, elastin homeostasis has been implicated in the pathophysiology of FPFD. Lysyl oxidase-like 1 knockout (LOXL1-KO) mice demonstrate abnormal elastic fiber homeostasis and develop FPFD after parturition. We compared the lower urogenital tract (LUT) anatomy and function in LOXL1-KO mice with and without POP. LUT anatomy was assessed in LOXL1-KO mice over 28 wk. Pelvic visceral anatomy in LOXL1-KO was evaluated with a 7-Tesla magnetic resonance imaging (MRI) scanner. LUT function was assessed using conscious cystometry and leak point pressure (LPP) testing. Quantitative histological analysis of elastic fibers was performed on external urethral sphincter (EUS) cross sections. By 25 wk of age, 50% of parous LOXL1-KO mice developed POP. LOXL1-KO mice with POP had greater variability in the size and location of the bladder on MRI compared with mice without POP. Parity and POP were associated with lower LPP. Elastin clusters were significantly increased in the EUS of LOXL1-KO mice with POP. Because parity triggers POP in LOXL1-KO mice, LOXL1-KO mice with POP have variable internal pelvic anatomy, and both parity and POP are associated with a decrease in LPP, we conclude that LOXL1 LUT anatomical and functional phenotype resembles FPFD in humans. The increase in elastin clusters in the urethra of LOXL1-KO mice with POP suggests that elastin disorganization may lead to functional abnormalities. We conclude that LOXL1 warrants further investigation in the pathphysiology of FPFD.

Periurethral Injection of Sustained Release Basic Fibroblast Growth Factor Improves Sphincteric Contractility of the Rat Urethra Denervated by Botulinum-A Toxin

We evaluated the effects of sustained release basic fibroblast growth factor injection in rat urethra denervated by botulinum-A toxin (Wako Life Science, Osaka, Japan). A total of 30 female Sprague-Dawley rats underwent periurethral injection of 10 U botulinum-A toxin to induce chemical denervation of the urethral sphincter. Leak point pressure in the waking state was determined and a significant decrease in leak point pressure vs that in control rats was confirmed (mean +/- SD 58.7 +/- 6.2 vs 120.7 +/- 13.0 cm H(2)O, p <0.0001). Two weeks later 0, 50 and 200 microg basic fibroblast growth factor incorporating 200 microl gelatin hydrogels in 10 rats each were injected into the urethral sphincter, enabling sustained release of basic fibroblast growth factor for 2 weeks. Four weeks later injection leak point pressure measurement and histological evaluation of the urethra were performed. Leak point pressure in rats with 50 and 200 microg basic fibroblast growth factor injection was significantly higher than in rats with the 0 microg injection (82.7 +/- 9.0 vs 95.1 +/- 6.2 and 119.3 +/- 8.1 cm H(2)O, p = 0.0021 and <0.0001, respectively). Maximum cross-sectional area of the urethral smooth muscle layer in the 50 and 200 microg groups significantly increased compared with that in the urethra in the 0 micro group, which was considered 100% (114.1% +/- 15.8% and 132.5% +/- 13.4%, p = 0.029 and <0.0001, respectively). Similarly the cross-sectional area of the striated sphincter in the 50 and 200 microg groups was greater than the 100% in the 0 microg group (112.3% +/- 15.6% and 124.3% +/- 14.1%, p = 0.069 and 0.0007, respectively). Vascular density in the urethral peri-atrophic zone in the 50 and 200 microg groups was significantly higher than in the 0 microg group (p = 0.027 and <0.0001, respectively). Sustained release basic fibroblast growth factor injection in the chemically denervated urethral sphincter facilitates regeneration of the urethral muscles and improves sphincteric contractility. Endoscopic periurethral injection of basic fibroblast growth factor incorporating gelatin hydrogels may be an attractive therapy for stress urinary incontinence.

Evaluation of a selective neurectomy model for low urethral pressure incontinence in female dogs

To develop a model of low urethral pressure incontinence and compare the relative contributions of the pudendal and hypogastric nerves with urethral function by performing selective neurectomy and ovariohysterectomy in dogs. 19 healthy Foxhounds. Dogs were allocated into 2 groups. The first group (10 dogs) underwent bilateral hypogastric neurectomy and ovariohysterectomy and subsequent bilateral pudendal neurectomy. The second group (9 dogs) underwent bilateral pudendal neurectomy and subsequent hypogastric neurectomy and ovariohysterectomy. Urethral pressure profilometry and leak point pressure (LPP) tests were performed before and after each neurectomy. Before surgery, mean +/- SD LPP and maximal urethral closure pressure (MUCP) in all dogs were 169.3 +/- 24.9 cm H2O and 108.3 +/- 19.3 cm H2O, respectively; these values decreased to 92.3 +/- 27 cm H2O and 60.7 +/- 20.0 cm H2O, respectively, after both selective neurectomy surgeries. There was a progressive decline of LPP after each neurectomy; however, MUCP decreased only after pudendal neurectomy. Fifteen dogs had mild clinical signs of urinary incontinence. All dogs appeared to have normal bladder function as indicated by posturing to void and consciously voiding a full stream of urine. Urinary tract infection did not develop in any dog. Hypogastric and pudendal neurectomy and ovariohysterectomy caused a maximum decrease in LPP whereas pudendal neurectomy caused a maximum decrease in MUCP. IMPACT ON HUMAN MEDICINE: This model may be useful for evaluation of treatments for improving urinary control in postmenopausal women.

Bladder autoaugmentation byvesicomyotomy in the pediatric neurogenic bladder

Objectives. The authors describe the procedure of bladder autoaugmentation by vesicomyotomy in 12 pediatric patients with neurogenic bladders. Methods. Indications for augmentation included low-capacity, high-pressure bladderswith incontinence despite maximal anticholinergic therapy. Clean intermittent catheterization was successfully reinstituted postoperatively and no patient has subsequently required enterocystoplasty. Results. There were no major complications and eight patients underwent concurrent procedures on the bladder. Urodynamic studies revealed a mean increase in capacity of 40% and a mean decrease in leak point pressure of 33% compared with preoperative values. Conclusions. Early clinical experience would suggest that vesicomyectomy (excision ofreleased detrusor) offers no advantages over vesicomyotomy in pediatric patients. Vesicomyotomy (simple incision into detrusor) proved to be a simple technique that could be safely performed in pediatric patients.