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Biomedical subjects

M B Chancellor

Publications and source records attributed to M B Chancellor.

At least 73 records · Page 4Linked to original sources
PubMed1999

Influence of glutamate receptor antagonists on micturition in rats with spinal cord injury.

This study was undertaken to determine if an AMPA (LY215490) or an NMDA (MK-801) glutamatergic receptor antagonist can reduce urinary tract dysfunctions related to detrusor hyperreflexia and detrusor-sphincter dyssynergia in awake, spinal cord-injured (SCI) rats. Experiments were performed on female Sprague-Dawley rats in which the spinal cord was completely transected at T(8-10) level, 2-3 weeks prior to performing an intravesical continuous infusion cystometrogram (CMG). Bladder volume threshold (VT) for inducing voiding and voiding efficiency (VE) were determined by measuring voided volumes and residual volumes (RV). After control CMGs were performed, cumulative intravenous doses of LY215490 (0.1, 1, and 10 mg/kg) or MK-801 (0.03, 0.3, and 3 mg/kg) were administered at 120-min intervals. Small doses of LY215490 (0.1 mg/kg) or MK-801 (0. 03 and 0.3 mg/kg) did not affect any parameters. A large dose (10 mg/kg) of LY215490 decreased maximal voiding pressure (MVP) by 27% and increased RV by 119% and VT by 58% but did not decrease VE. The highest cumulative dose (3 mg/kg) of MK-801 significantly increased RV by 134% and VT by 44% and markedly decreased VE by 60% and MVP by 18%. The effects of LY215490 to reduce MVP and increase VT without changing VE suggest that an AMPA receptor antagonist might be useful in treating detrusor-sphincter dyssynergia and bladder hypertrophy after SCI. The effect of MK-801 to markedly reduce VE indicates that NMDA receptor antagonists may exacerbate neurogenic bladder dysfunction in SCI patients.

Animals↗
PubMed1999

Effect of intravesical nitric oxide therapy on cyclophosphamide-induced cystitis.

PURPOSE: This study was conducted to examine effects of nitric oxide (NO) donors on bladder hyperactivity induced by cyclophosphamide (CYP)-induced cystitis. MATERIALS AND METHODS: Female Sprague-Dawley rats received a single intraperitoneal injection of CYP (100 mg./kg.), and then their micturition pattern including mean micturition volume and the number of micturitions during 24 hours was recorded in a metabolic cage before and after CYP treatment. Forty-eight hours after CYP injection, bladder function under urethane anesthesia was evaluated by cystometry with continuous saline infusion (0.04 ml. per minute) or under isovolumetric conditions (0.8 ml. bladder volume). NO donors, S-nitroso-N-acetyl-penicillamine (SNAP, 2 mM) or sodium nitroprusside (SNP, 1 mM), and an NO synthase (NOS) inhibitor, N-nitro-L-arginine methyl ester (L-NAME, 20 mM) were administered intravesically. Direct action of SNAP on bladder afferent neurons was also tested in a patch-clamp recording study. RESULTS: The number of micturitions significantly increased during the first 24 hours after CYP injection (19.0 +/- 0.88 versus 92.1 +/- 16.3 micturitions/24 hours, mean +/- SE, n = 25) (p <0.001). There was no significant difference in total micturition volume before (12.3 +/- 1.0 ml./24 hours) and after CYP treatment (15.6 +/- 1.5 ml./24 hours). During continuous infusion cystometry, intercontraction interval (ICI) was smaller in CYP-injected rats than in control rats. In CYP-injected animals, NO donors increased the ICI, but did not change the amplitude of bladder contractions. Continuous intravesical infusion of the NOS inhibitor did not alter the cystometric parameters. During cystometry under isovolumetric conditions, contraction frequency was decreased after NO donor administration. NO donors did not influence bladder activity in control rats. In patch clamp recordings, when SNAP (500 microM) was directly applied to dissociated afferent neurons innervating the urinary bladder, high-voltage-activated Ca2+ channel currents were suppressed by approximately 30%. CONCLUSIONS: Intravesical NO donors can suppress CYP-induced bladder hyperactivity. We hypothesize that the effect of NO donors is not due to smooth muscle relaxation, but rather due to an inhibitory effect on bladder afferent pathways that was manifested by an increase in intercontraction interval without changes in contraction amplitude. NO donors may be considered as a possible treatment of CYP-induced and other types of bladder inflammation.

Administration, Intravesical↗
PubMed1999

Advantages and risks of ileovesicostomy for the management of neuropathic bladder.

OBJECTIVES: To evaluate the efficacy and complications of ileovesicostomy in patients with neurogenic bladder dysfunction. METHODS: Fifteen consecutive neurologically impaired patients (8 from multiple sclerosis, 4 from spinal cord injury, 3 from other causes) with complications of previous bladder management underwent ileovesicostomy. There were 10 women and 5 men. All patients were either poor candidates for or refused continent urinary diversion or bladder augmentation cystoplasty. RESULTS: At a mean follow-up of 23.2 months, 14 of 15 patients had low-pressure urine drainage through their ileovesicostomy. Four women with documented preoperative detrusor hyperreflexia had postoperative intermittent mild urge incontinence per native urethra. They did not require any further treatment, except for oral anticholinergic drugs (oxybutynin and tolterodine). Because of persistent severe urge incontinence, 1 woman required conversion of her ileovesicostomy to an ileal conduit with concurrent cystectomy. The ileovesicostomy of another myelodysplastic man who had four failed artificial urinary sphincters in the past was also converted to an ileal conduit because of persistent urethroperineal fistula despite perineal urethral closure. Renal function was preserved in all patients. Long-term complications were stomal stenosis in 2 patients, bladder and kidney stone formation in 5, and symptomatic urinary tract infections in 3. CONCLUSIONS: Ileovesicostomy can be safely performed in neurologically impaired women and men. Severe preoperative detrusor hyperreflexia with urge incontinence appears to be a risk factor for persistent urge incontinence postoperatively in women. Continued routine urologic surveillance for infection and stones is mandatory. Ileovesicostomy is a versatile procedure for neurologically impaired patients, because it can be converted to a conventional ileal conduit if necessary. In addition, in cases of neural recovery, the ileal "chimney" can be excised and the patient's original lower urinary tract would be preserved.

Adult↗
PubMed1999

Changes in micturition after spinal cord injury in conscious rats.

OBJECTIVES: To determine the feasibility of urodynamic monitoring of voiding function in conscious, female spinal cord-injured (SCI) rats and to compare the voiding function in SCI rats and those with normal spinal cord (NSC). METHODS: Cystometrograms were performed on conscious, female Sprague-Dawley rats. Parameters measured included voided volume, residual volume, volume threshold for inducing micturition, voiding efficiency, micturition pressure, pressure threshold for inducing micturition, and bladder contraction duration. SCI animals were studied 2 to 3 weeks after T8-T10 spinal cord transection. RESULTS: Approximately one half of SCI rats exhibited uninhibited bladder contractions before voiding. These contractions were not observed in NSC rats. Compared with NSC rats, SCI rats had larger volume thresholds (1.43 versus 0.34 mL, P <0.001) and voided volumes (0.72 versus 0.31 mL, P <0.01). Although SCI rats had larger micturition pressures (65 versus 35 cm H2O, P <0.001), residual volumes were increased (0.71 versus 0.03 mL, P <0.001) and voiding efficiency was decreased (50% versus 92%, P <0.001) compared with the measurements in NSC rats. The micturition pressure threshold was slightly lower (23%, P <0.05) and the bladder contraction duration was longer (33%, P <0.05) in SCI rats than in NSC rats. CONCLUSIONS: Cystometric studies in conscious female SCI and NSC rats revealed significant changes in the activity of the lower urinary tract after spinal cord transection. Fifty-five percent of SCI rats exhibited detrusor hyperreflexia during bladder filling and decreased voiding efficiency compared with NSC animals. This method of cystometric evaluation in the conscious animal is likely to be useful for evaluating new pharmacologic treatments for neurogenic bladder dysfunction.

Animals↗
PubMed1999

Intravesical capsaicin and resiniferatoxin therapy: spicing up the ways to treat the overactive bladder.

PURPOSE: Pharmacological treatment of the overactive bladder relies on partially blocking the efferent parasympathetic innervation to the detrusor with anticholinergic drugs. However, often these drugs have troublesome side effects and doses are insufficient to restore continence in patients with detrusor instability. We present the background, basic and clinical research with intravesical instillation of capsaicin and resiniferatoxin as treatments for the overactive bladder. MATERIALS AND METHODS: Capsaicin, the main pungent ingredient in hot peppers of the genus Capsicum, is a specific neurotoxin that desensitizes C fiber afferent neurons which may be responsible for signals that trigger detrusor overactivity. RESULTS: In the last 6 years studies have demonstrated encouraging improvement in lower urinary tract symptoms with minimal long-term complications. Most of these studies have also demonstrated that the acute pain and irritation associated with capsaicin are major deterrents to widespread use. Therefore, resiniferatoxin, an ultra-potent analogue of capsaicin which appears to have similar efficacy but less acute side effects, may be more useful. CONCLUSIONS: Intravesical capsaicin and resiniferatoxin are novel and promising treatments for the overactive bladder, with profound basic and clinical implications.

Administration, Intravesical↗
PubMed1999

Urethral afferent nerve activity affects the micturition reflex; implication for the relationship between stress incontinence and detrusor instability.

PURPOSE: A causative relationship between stress urinary incontinence (SUI) and detrusor instability has been suspected but never proven. Many women with mixed incontinence have resolution of detrusor instability after surgical correction of SUI. We sought experimental support that stimulation of urethral afferent nerves can induce or change reflex detrusor contractions. MATERIALS AND METHODS: Urethral perfusion pressure and isovolumetric bladder pressure were measured with catheters inserted through the bladder dome in urethane anesthetized female S.D. rats (250 to 300 grams; n = 12). The catheter assembly was seated securely in the bladder neck to block passage of fluid between the bladder and urethra without affecting the nerve supply to the organs. The external urethra was not catheterized. Responses were examined in the control state at a urethral saline perfusion speed of 0.075 ml. per minute. Intraurethral drugs were administered following blockade of striated sphincter activity with intravenous alpha-bungarotoxin (0.1 mg./kg.). RESULTS: Stopping the urethral saline infusion caused a significant decrease in micturition frequency in approximately 50% of the animals studied (n = 12). Intraurethral lidocaine (1%) infused at 0.075 ml. per minute caused a slight decrease in urethral perfusion pressure but no change in detrusor contraction amplitude. However, intraurethral lidocaine caused a significant (45%) decrease in the bladder contraction frequency (n = 5). The micturition frequency returned to baseline 30 minutes after stopping lidocaine infusion. Intraurethral infusion of nitric oxide (NO) donors (S-nitroso-N-acetylpenicillamine [SNAP] (2 mM) or nitroprusside (1 mM) immediately decreased urethral perfusion pressure by 30 to 37% (n = 5). A 45 to 75% decrease (n = 5) in bladder contraction frequency was also seen, which was similar to that observed following lidocaine. Neither NO donor changed the amplitude of bladder contractions. CONCLUSIONS: These results indicate that in the anesthetized rat activation of urethral afferents by urethral perfusion can modulate the micturition reflex. Thus in patients with stress urinary incontinence, leakage of urine into the proximal urethra may stimulate urethral afferents and facilitate voiding reflexes. This implies that stress incontinence can induce and/or increase detrusor instability. These findings have significant implications for the treatment of patients with mixed urge and stress incontinence. Correction of stress incontinence by surgery or pelvic floor exercise in patients with mixed incontinence may resolve the detrusor instability.

Anesthetics, Local↗
PubMed1999

Long-term followup of the North American multicenter UroLume trial for the treatment of external detrusor-sphincter dyssynergia.

PURPOSE: We determine the long-term efficacy and safety of the UroLume stent as minimally invasive treatment for external detrusor-sphincter dyssynergia in spinal cord injured men. MATERIALS AND METHODS: A total of 160 spinal cord injured men with a mean age plus or minus standard deviation of 36.3 +/- 12.1 years (range 16 to 74) were prospectively treated with an endoprosthesis at 15 centers as part of the North American UroLume trial for external detrusor-sphincter dyssynergia. Urodynamic parameters, including voiding pressure, residual urine volume and bladder capacity, were compared before treatment and at 1, 2, 3, 4 and 5 years after treatment. RESULTS: Mean voiding pressure was 75.1 +/- 28.2 cm. water before treatment in the 160 patients, and 37.4 +/- 23.9 at year 1 in 97, 39.5 +/- 22.2 at year 2 in 84, 42.6 +/- 27.3 at year 3 in 61, 46.3 +/- 33.2 at year 4 in 57 and 44.2 +/- 28.9 cm. at year 5 in 41 after stent insertion (p <0.001). Residual urine volume decreased after stent placement and was maintained throughout the 5-year followup (p <0.001). Mean cystometric capacity remained constant from 269 +/- 155 before insertion to 337 +/- 182 ml. 5 years later (p = 0.17). Hydronephrosis and autonomic dysreflexia improved or stabilized in most patients with functioning stents. Stent explant was necessary in 24 patients (15%), of whom 4 (16.7%) had another stent implanted. CONCLUSIONS: The UroLume stent demonstrates long-term safety and efficacy for the treatment of external detrusor-sphincter dyssynergia. The outcome was similar in men with and without previous sphincterotomy.

Adolescent↗
PubMed1999

Sphincteric stent versus external sphincterotomy in spinal cord injured men: prospective randomized multicenter trial.

PURPOSE: In a prospective randomized multicenter trial we compared the treatment results of conventional external sphincterotomy with those of UroLume sphincteric stent prosthesis placement in men with spinal cord injury and external detrusor-sphincter dyssynergia. MATERIALS AND METHODS: We randomized 57 men with spinal cord injury in whom urodynamics verified external detrusor-sphincter dyssynergia into 2 groups to undergo either sphincter defeating procedure. We compared the primary urodynamic parameter of maximum detrusor pressure, and secondary urodynamic parameters of bladder capacity and post-void residual urine volume in men who underwent sphincterotomy or sphincteric stent placement. Parameters were measured preoperatively, and 3, 6, 12 and 24 months postoperatively. Patients completed questionnaires regarding voiding sensation and quality of life issues at each followup visit. RESULTS: Demographic data of the 26 patients treated with sphincterotomy and the 31 treated with sphincteric stent placement were statistically similar. Preoperatively mean maximum detrusor pressure plus or minus standard deviation in sphincterotomy and stent cases was 98.3 +/- 27.6 and 95.7 +/- 27.7 cm. water, respectively (p = 0.73). At 12 months mean maximum detrusor pressure decreased to 48.9 +/- 16.4 and 52.6 +/- 31.6 cm. water in the sphincterotomy and stent groups, respectively (p = 0). Preoperatively mean bladder capacity in sphincterotomy and stent cases was 245 +/- 158 and 251 +/- 145 ml., respectively (p = 0.87). Bladder capacity did not change significantly in either treatment group throughout followup. Preoperatively mean post-void residual urine volume in the sphincterotomy and stent groups was 212 +/- 163 and 168 +/- 114 ml., respectively (p = 0.33). Residual urine volume decreased in each group at some but not all followup evaluations. The duration of hospitalization was greater for sphincterotomy than stenting (p = 0.036). Six stents required explantation. CONCLUSIONS: The UroLume stent is as effective as conventional external sphincterotomy for treating external detrusor-sphincter dyssynergia. However, sphincteric stent placement is advantageous because it involves shorter hospitalization and is potentially reversible.

Adult↗
PubMed1999

Tolterodine for overactive bladder: time to onset of action, preferred dosage, and 9-month follow-up.

This is a prospective study of 28 patients who had urinary frequency (>8 times/day) and either urgency or urge incontinence (>1 time/day). After a 2-week run-in period (visit 1), the patients were started on tolterodine 1 mg twice a day (bid) (visit 2). They were followed at 4 and 8 weeks (visits 3 and 4). The patients were contacted by telephone 1 week after visit 2. Tolterodine was increased to 2 mg bid if the patient had incomplete improvement at either the initial phone call or during visit 3. Evaluation criteria were daily micturition charts including urinary frequency, nocturia, leakage episodes, average urine volume per day, and average voided volume. Tolterodine was well tolerated without side effects in 20 (80%) of 28 patients. Eight patients (20%) dropped out after enrollment because of side effects in 3, no improvement in 2, and missing visits (>1) in 3. Drug dosage in the 20 patients who tolerated tolterodine was 1 mg bid in 3 and 2 mg bid in 17 (85%). According to micturition charts, urinary frequency, nocturia, and leakage episodes decreased significantly after tolterodine treatment, whereas average urine volume per day and average voided volume did not change significantly. There were no electrocardiographic or biochemical abnormalities due to tolterodine treatment. Mean follow-up was 9.4 months. All 20 patients who tolerated tolterodine continue to take the medication without significant side effects. We conclude that tolterodine is well tolerated and effective for overactive bladders. Two milligrams bid is the dosage preferred by the majority of patients and the onset of action is seen within 1 week of treatment. Long-term compliance and efficacy are excellent, with no dropout in >9 months of follow-up.

Adult↗
PubMed1999

Beneficial effect of intranasal desmopressin for men with benign prostatic hyperplasia and nocturia: preliminary results.

The aim of this study was to determine the efficacy of intranasal desmopressin in the treatment of nocturnal polyuria in men with benign prostatic hyperplasia (BPH). Twelve men with BPH were treated with intranasal desmopressin at bedtime for nocturnal polyuria. All patients underwent video-urodynamic evaluation. The number of nocturia episodes was the dependent variable. Exclusion criteria included nephrolithiasis, active urinary tact infection, and history of myocardial infarction, congestive heart failure, and angina. Ten of 12 patients improved with the intranasal desmopressin therapy. Nocturia episodes decreased from a median of 3.6 +/- 0.5 episodes/night before treatment to 1.8 +/- 1.1 episodes/night 3 months after therapy (p = .01). The American Urological Association symptom index decreased from 19 +/- 6 before treatment to 12 +/- 6 after therapy (p = .02). Hyponatremia did not occur. We conclude that intranasal desmopressin is a promising therapy for nocturnal polyuria in selected BPH patients.

Administration, Intranasal↗
PubMed1999

Medical and minimally invasive treatment of urinary incontinence.

Newer agents and procedures give urologists more options in treating patients who have urinary incontinence related to such etiologies as an ineffective sphincter, detrusor hypersensitivity, obstruction, or a combination of these. Abolition of the involuntary contractions characteristic of detrusor instability can be accomplished pharmacologically or surgically. First-line anticholinergic agents are tolterodine and oxybutynin XL, given orally. Alternatively, intravesical administration provides a high concentration of drug, such as capsaicin or resiniferatoxin, at the detrusor muscle level. However, this commits the patient to intermittent self-catheterization. Surgery is reserved for those who have failed prolonged trials of conservative therapies. For patients with intractable urge incontinence, urologists have the new technique of sacral nerve stimulation.

Journal Article↗