Christopher P. Smith

Improved sphincter contractility after allogenic muscle-derived progenitor cell injection into the denervated rat urethra.

OBJECTIVESnTo study the physiologic outcome of allogenic transplant of muscle-derived progenitor cells (MDPCs) in the denervated female rat urethra.nnnMETHODSnMDPCs were isolated from muscle biopsies of normal 6-week-old Sprague-Dawley rats and purified using the preplate technique. Sciatic nerve-transected rats were used as a model of stress urinary incontinence. The experimental group was divided into three subgroups: control, denervated plus 20 microL saline injection, and denervated plus allogenic MDPCs (1 to 1.5 x 10(6) cells) injection. Two weeks after injection, urethral muscle strips were prepared and underwent electrical field stimulation. The pharmacologic effects of d-tubocurare, phentolamine, and tetrodotoxin on the urethral strips were assessed by contractions induced by electrical field stimulation. The urethral tissues also underwent immunohistochemical staining for fast myosin heavy chain and CD4-activated lymphocytes.nnnRESULTSnUrethral denervation resulted in a significant decrease of the maximal fast-twitch muscle contraction amplitude to only 8.77% of the normal urethra and partial impairment of smooth muscle contractility. Injection of MDPCs into the denervated sphincter significantly improved the fast-twitch muscle contraction amplitude to 87.02% of normal animals. Immunohistochemistry revealed a large amount of new skeletal muscle fiber formation at the injection site of the urethra with minimal inflammation. CD4 staining showed minimal lymphocyte infiltration around the MDPC injection sites.nnnCONCLUSIONSnUrethral denervation resulted in near-total abolishment of the skeletal muscle and partial impairment of smooth muscle contractility. Allogenic MDPCs survived 2 weeks in sciatic nerve-transected urethra with minimal inflammation. This is the first report of the restoration of deficient urethral sphincter function through muscle-derived progenitor cell tissue engineering. MDPC-mediated cellular urethral myoplasty warrants additional investigation as a new method to treat stress urinary incontinence.

Technique of combined pubovaginal sling and cystocele repair using a single piece of cadaveric dermal graft

OBJECTIVESnTo investigate the feasibility of using a single piece of cadaveric dermal allograft for the repair of stress urinary incontinence (SUI) with concurrent cystocele.nnnMETHODSnNineteen patients with combined SUI and symptomatic grade III cystoceles were treated. Eleven of 19 patients had undergone prior repairs for SUI. All patients underwent a combined pubovaginal sling procedure and cystocele repair using a single piece of cadaveric dermal allograft (3 x 7 cm). The single strip of dermal graft was placed in a longitudinal direction along the anterior vagina. The distal segment of the allograft supported the urethra, and the proximal portion supported the central cystocele defect and was sutured to the pubocervical fascia. The mean follow-up was 28 +/- 4 months and patients were monitored by physical examination, videourodynamic studies, and completion of the bladder bothersome visual analog scale.nnnRESULTSnOf the 19 patients, 1 developed an acute infection and failure of the graft after presenting with fever, discharge, dysuria, and incontinence. The autolysed graft was removed, and she subsequently underwent successful autologous fascial repair. Of the remaining 18 patients, 17 were cured of their SUI, including 10 who had had prior repairs, and 16 had no recurrence of cystocele and 2 had asymptomatic grade I and II cystoceles. One patient developed de novo detrusor instability that was successfully treated with anticholinergic medication. No cases of urethral obstruction occurred.nnnCONCLUSIONSnAlthough the follow-up was short, the use of a single piece of cadaveric dermal graft slings for concomitant pubovaginal sling and cystocele repair is feasible and simple to perform. At more than 2 years of follow-up, documented by videourodynamic studies, neither urethral obstruction nor symptomatic cystocele recurrence was found.

Effect Of Controlled-Release Oxybutynin On Neurogenic Bladder Function In Spinal Cord Injury

Abstract Objective: This study evaluated the effects and tolerability of extended-release oxybutynin chloride on the frequency of voiding and catheterization and urodynamic capacity in spinal cord injury (SCI) patients with defined detrusor hyperreflexia. Methods: This was a 1 2-week, prospective, dose-titration study of extended-release oxybutynin (oxybutynin XL) . SCI patients with urodynamically defined detrusor hyperreflexia were recruited for this study. Following a 7 -day washout period, patients were evaluated via video-urodynamic study and then treatment was initiated at a dosage of 1 0 mg per day. Dosage was increased in weekly intervals to a maximum of 30 mg per day. Micturation frequency diaries and urodynamics were completed at baseline and repeated at week 1 2. Tolerability information was collected at each follow-up visit. Results: Ten patients (mean age = 49 years) with complete or incomplete SCI were enrolled. Participants reported clinical improvement (decreased urinary frequency and fewer incontinence episodes) with oxybutynin therapy following titration to 30 mg per day. All patients chose a final effective dosage of greater than 1 0 mg, with 4 patients taking the maximum of 3 0 mg per day. Mean cystometric bladder capacity increased from 2 7 4 mL to 3 80 mL (P = 0.008). No patient experienced serious adverse events during the 12-week study. Conclusion: Oxybutynin XL is safe and effective in patients with detrusor hyperreflexia secondary to SCI. The onset of clinical efficacy occurs within 1 week, and daily dosages up to 30 mg are well tole rated.

Botulinum toxin urethral sphincter injection resolves urinary retention after pubovaginal sling operation.

Abstract: The management of prolonged urinary retention following pubovaginal sling surgery typically involves transvaginal urethrolysis for anatomical urethral obstruction. Brubaker [1] recently reported on urethral sphincter abnormalities as a cause of postoperative urinary retention following either Burch suspension or a pubovaginal sling procedure. We report a case of functional urethral obstruction and detrusor acontractility following pubovaginal sling surgery that was successfully treated by botulinum A toxin urethral sphincter injection.

Change in muscarinic modulation of transmitter release in the rat urinary bladder after spinal cord injury

Muscarinic facilitation of 14C-ACh release from post-ganglionic parasympathetic nerve terminals was studied in bladder strips prepared from spinal intact (SI) and spinal cord transected (SCT) rats. The spinal cord was transected at the lower thoracic spinal segments 3 weeks prior to the experiments. Using non-facilitatory stimulation (2 Hz) the release of ACh in spinal intact rats did not change in the presence of a non-specific muscarinic antagonist, atropine (100 nM), an M(1) specific antagonist (pirenzepine, 50 nM) or an M(1)-M(3) specific antagonist (4-DAMP, 5 nM). However, during a facilitatory stimulation paradigm (10 Hz or 40 Hz, 100 shocks) atropine and pirenzepine, but not 4-DAMP inhibited the release of ACh in bladders from spinal intact rats, indicating an M(1) receptor-mediated facilitation. In spinal cord transected rats, 2 Hz stimulation-induced release was significantly inhibited by atropine or 4-DAMP but not by pirenzepine indicating that a pre-junctional facilitatory mechanism mediated via M(3) muscarinic receptors could be induced by a non-facilitatory stimulation paradigm after spinal injury. In bladders of spinal cord transected rats, 10 Hz stimulation-evoked release of ACh was also inhibited by atropine and 4-DAMP (5 nM) but not by pirenzepine (50 nM). These results indicate that pre-junctional muscarinic receptors at cholinergic nerve endings in the bladder change after chronic spinal cord injury. It appears that low affinity M(1) muscarinic receptors are replaced by high affinity M(3) receptors. This change in modulation of ACh release may partly explain the bladder hyperactivity after chronic spinal cord injury.

Effect of cryoinjury on the contractile parameters of bladder strips: A model of impaired detrusor contractility

In anesthetized Sprague-Dawley rats, the bladder was exposed and cryoinjury was induced by abruptly freezing the serosal side of the bladder wall with a chilled aluminum rod previously placed on dry ice (-40 degrees C). Five days later, the rats were euthanized, and strips were prepared from the area adjacent to the injury. Neurally and alpha,beta methylene-ATP (alpha,beta m-ATP; 50 microM)-evoked contractions were measured in bladder strips from cryoinjured or intact bladders prepared from sham-operated rats. Cryoinjured bladder strips produced significantly lower contractile forces than intact strips to electrical stimulation at higher (10-40 Hz) frequencies. The maximal rate of the neurally evoked contractions was slower in the cryoinjured bladders. The contractile response to alpha,beta m-ATP was smaller in the cryoinjured preparations indicating that the changes may have also occurred at the postjunctional site. In addition, atropine was more effective at inhibiting the neurally evoked contractions in the cryoinjured bladder strips suggesting that a cholinergic dominance occurs after cryoinjury. It is concluded that cryoinjury is a viable method of causing a defined, reproducible injury to the urinary bladder resulting in impaired function of both the cholinergic transmission and the smooth muscle. The bladder cryoinjury can be used as a model for studying impaired bladder compliance and detrusor contractility as well as treatments that may improve bladder function such as tissue engineering.

Neurogenic bladder model for spinal cord injury: spinal cord microdialysis and chronic urodynamics.

We describe an animal model to study neurotransmitter changes in parallel with urodynamic testing following Spinal Cord Injury (SCI). Urodynamic access was achieved using a subcutaneously placed 7 French dual lumen portacatheter. Spinal cord injury was induced by weight drop technique onto exposed dura at T8. The L6-S1 detrusor nuclei were localized stereotactically and microdialysis probe placement was confirmed through histologic methods. Chronic urodynamics revealed detrusor hyperreflexia (DH) 14 days following SCI. In vivo microdialysis of spinal cord amino acids was performed using CMA 11 (240 uM) probes in halothane-anesthetized rats at baseline and intervals of 20-30 min following spinal cord injury. Significant increases in the excitatory amino acid glutamate, and the inhibitory amino acids, glycine and taurine, were seen following spinal cord injury. Amino acid levels peaked at approximately 40 min following contusion injury with glycine demonstrating the highest levels of all amino acids measured. This neurogenic rat model provides a useful means of examining the effects of spinal cord injury on bladder function. By utilizing spinal cord microdialysis, one could intervene at the level of the detrusor nuclei to modulate bladder function.

Effect of KW-7158, a putative afferent nerve inhibitor, on bladder and vesico-vascular reflexes in rats.

The effects of KW-7158, a putative afferent nerve inhibitor, on reflex bladder activity and vesico-vascular reflexes were evaluated in urethane anesthetized SD rats with normal and xylene-irritated bladders. The bladder was filled with saline until the appearance of large amplitude spontaneous bladder contractions (LA-BC). Vesico-vascular reflexes were measured as increases in systolic arterial blood pressure during LA-BC or when the bladder was distended by a range of pressures. In normal rats, KW-7158 (10 and 100 microg/kg, i.v.) did not alter the amplitude or volume threshold for inducing LA-BC but increased the intercontraction interval. After xylene-irritation, which decreased volume threshold and intercontraction interval and induced small amplitude bladder contractions, KW-7158 increased volume threshold (65%) and intercontraction interval (150%) and decreased the number of small amplitude bladder contractions. Vesico-vascular reflexes induced during LA-BC or by bladder distension were suppressed (19.4-100%) by KW-7158. The effect of KW-7158 to depress vesico-vascular reflexes as well as xylene-induced bladder hyperactivity without altering the amplitude of contractions is consistent with the view that the drug affects reflex bladder activity at least in part by depressing afferent pathways.

Genitourinary tract patent update

The treatment of urinary incontinence is a booming business with over

Neurovesical Dysfunction in Postural Tachycardia Syndrome (POTS)

26 billion being spent annually. Pharmacological research is rapidly increasing as scientists attempt to modulate complex micturition pathways to result in meaningful clinical improvement of conditions such as urge and stress incontinence. Antimuscarinic agents remain the mainstay in the treatment of urge incontinence with newer agents having functional selectivity for the bladder to prevent unwanted anticholinergic side effects. Other exciting pharmacological targets to treat urinary incontinence include β3 adrenoceptor agonists and agents that affect afferent pathways (i.e. neurokinin antagonists). Non-pharmacologic treatment of urinary incontinence includes various injectable agents, and electrical or magnetic stimulation. Finally, recent patents have addressed tissue engineering techniques to treat urinary incontinence via cultured chondrocytes, bladder smooth muscle, or muscle derived stem cells.