A new injectable bulking agent for treatment of stress urinary incontinence: results of a multicenter, randomized, controlled, double-blind study of Durasphere

OBJECTIVES

To assess the safety and effectiveness of Durasphere compared with bovine collagen in the treatment of stress urinary incontinence (SUI) due to intrinsic sphincter deficiency (ISD).

METHODS

This multicenter, randomized, controlled, double-blind trial was composed of 355 women diagnosed with SUI due to ISD and used a standardized pad test and the Stamey continence grade as the primary endpoints. The participants' ages ranged from 26 to 84 years. All patients had an abdominal leak point pressure of less than 90 cm H(2)O (average 51).

RESULTS

At 12 months after the first injection, the two materials were equivalent with respect to the improvement in continence grade and pad weight testing. Less Durasphere was injected to obtain comparable clinical results (Durasphere 4.83 mL versus bovine collagen 6.23 mL, P <0.001). When examined 1 year after the date of the last treatment, 49 (80.3%) of the 61 women treated with Durasphere showed improvement of 1 continence grade or more compared with 47 (69.1%) of 68 women treated with bovine collagen (P value for difference = 0.162). Although the adverse events reported for both groups were similar, the Durasphere group had an increased short-term risk of urgency and urinary retention.

CONCLUSIONS

The use of Durasphere for the treatment of SUI due to ISD was equally effective as bovine collagen and used less material. The U.S. Food and Drug Administration granted market approval for Durasphere on September 13, 1999. The product design and initial clinical data suggest the potential for greater durability of the clinical benefit, with the possibility of a permanent solution for SUI due to ISD in some patients.

Preliminary investigation of the Irie inferior vena caval filter

PURPOSE

In vitro and in vivo investigations were performed to evaluate the Irie retrievable inferior vena caval (IVC) filter.

MATERIALS AND METHODS

The clot capturing performance of the Irie and five other IVC filters were assessed in both horizontal and vertical orientations within a pulsed-flow circuit with 240 clot challenges for each filter. Subjective comparisons of the flow disturbance characteristics of the Irie and three other filters were also performed. In vivo studies consisted of 13 Irie filter insertions and eight attempted retrievals in 11 pigs. Histologic evaluation of the IVC was performed with the Irie filter in situ and following retrieval.

RESULTS

In vitro testing demonstrated the clot capturing capability and flow disturbance characteristics of the Irie filter to be similar to those of other IVC filters. Filter deployment problems occurred during three of the 13 insertions. Six of the eight retrieval procedures were successful; four filters were retrieved 1 month after insertion. Follow-up cavography demonstrated two tilted filters and three caval perforations.

CONCLUSION

The performance of the Irie filter is similar to that of other currently available IVC filters. The filter can be retrieved after neointimal incorporation of the struts into the IVC wall.

Exogenous epidermal growth factor fails to accelerate functional recovery in the autotransplanted ischemic pig kidney

The reversibility of ischemic renal injury is dependent on epithelial cell regeneration and repopulation of the nephron. Renal cells produce and respond to many growth factors. In the rat, epidermal growth factor (EGF) is mitogenic for tubular cells and accelerates renal recovery after ischemia. We used a pig renal autotransplant model to evaluate the effect of exogenous EGF on renal recovery in a large animal more analogous to man. Group 1 animals underwent left autotransplant after 120 minutes of warm ischemia and received either a single intra-arterial dose of recombinant human EGF (EGF, 10(-7) M.) (N = 11) or vehicle alone (N = 6). Group 2 animals underwent left autotransplant after 72 hours of cold preservation with Collins' solution and received a similar intra-arterial dose plus a subcutaneous dose of EGF (0.5 ml. of 10(-3) M.) (N = 8) or vehicle alone (N = 6). Contralateral nephrectomy was performed in all animals. Daily creatinine measurements revealed no beneficial effect from EGF on recovery of renal function in Group 1 or 2 animals. Studies of EGF on pig proximal tubular cells demonstrated in vitro mitogenesis; autoradiography with 125I-EGF revealed binding of EGF throughout the kidney. Immunohistochemistry showed significant tubular cell proliferation in response to ischemic injury, without further enhancement from EGF. Thus, although exogenous EGF bound to pig kidney cells and stimulated cell proliferation, we were unable to demonstrate a clinically significant acceleration of recovery from ischemic injury.

Quantification and parametric imaging of renal cortical blood flow in vivo based on Patlak graphical analysis

Patlak graphical analysis was applied to quantify renal cortical blood flow with N-13 ammonia and dynamic positron emission tomography. Measurements were made in a swine model of kidney transplantation with a wide range of normal and abnormal renal blood flows (N = 57 studies) and in 20 healthy human volunteers (N = 45 studies). Estimates of renal cortical blood flow by the Patlak method were compared to those from a two-compartment model for N-13 ammonia. In addition, estimates of renal cortical blood flow by the N-13 ammonia PET approach were compared in 10 normal human volunteers to estimates by the metabolically inert, freely diffusible O-15 water and a one-compartment model. Patlak graphical analysis estimates of renal cortical blood flow correlated linearly with the standard two-compartment model in pigs (y = -0.05 + 1.01x, r = 0.99) and in humans (y = 0.57 + 0.88x, r = 0.93). Estimates of renal cortical blood flow by O-15 water in human volunteers were also linearly correlated with those by N-13 ammonia and the Patlak graphical analysis (y = 0.71 + 0.84x, r = 0.86). Renal cortical blood flow estimates were highly reproducible both with N-13 ammonia and O-15 water measurements in humans. It is concluded that the Patlak graphical analysis with N-13 ammonia dynamic positron emission tomograpic imaging renders accurate and reproducible estimates of renal cortical blood flow. Moreover, the graphical analysis approach is 1,000 times faster than the standard model fitting approach and suitable for generating parametric images of renal blood flow in the clinical setting.

Positron emission tomography: a new method for determination of renal function

Positron emission tomography (PET) is a newly evolving diagnostic modality that has been widely used in many facets of clinical medicine, but whose use in the diagnosis and management of disorders of the kidney has not been previously described. Employing the radiotracer N-13 ammonia, flow-dependent extraction of this compound after intravenous injection was used to measure renal blood flow (RBF) in a swine model (N = 10). A mean baseline value of 3.16 ml./min./gm. kidney was obtained with this method, in close agreement with values previously reported using established invasive techniques. Four conditions known to affect RBF were also studied to determine the ability of PET to detect changes in RBF. Kidneys were subjected to varying durations of warm ischemia, demonstrating a progressive decrease in RBF with increasing ischemic insult, with return to normal significantly impaired in animals exposed to the greatest degree of ischemia (180 minutes versus 150 or 120 minutes ischemia). Cross-transplant between animals produced acute allograft rejection and a corresponding marked decrease in RBF that failed to normalize. After unilateral nephrectomy, RBF increased two-fold in the remaining kidney by 7 days (R = 0.79), as predicted for compensatory renal hypertrophy. Lastly, there was an inverse, linear relationship between toxic cyclosporine level and RBF (R = 0.68), indicative of vascular-mediated cyclosporine nephrotoxicity. Positron emission tomography is safe and efficient, and yields an accurate measurement of RBF in several important physiologic states. The development of PET as a quantitative measure of renal function is promising.

Urinary tract infections in the pediatric patient

Urinary tract infections (UTIs) can be difficult to diagnose positively in the pediatric patient. The patient with such an infection, however, is at risk for subsequent morbidity such as recurrence, renal damage and hypertension. Accurate diagnosis in the very young child may require multiple urine specimens involving repeating bag specimens, catheterization, or suprapubic aspiration. Septic children and those with pyelonephritis must be hospitalized. Children younger than 6 years old need follow-up with radiographic studies to rule out reflux and congenital anomalies. The clinician plays a significant role in detecting possible UTIs, and providing patient education and support.

Oligosaccharides as an intravenous energy source in postsurgical patients: utilization when infused with glucose, amino acids, and lipid emulsion

Utilization of intravenously administered oligosaccharides was evaluated in postsurgical patients by infusing oligosaccharides simultaneously with glucose, amino acids, and lipid emulsion for 4 d postoperatively. Seven patients were infused with a nutritional regimen providing glucose, amino acids, lipid emulsion, and oligosaccharides and seven patients received a similar regimen without oligosaccharides. Patients infused with oligosaccharides received an overall mean (+/- SD) of 144 +/- 41.0 g oligosaccharides per day. The mean overall excretion of total glucose (free plus oligosaccharide-bound) was significantly greater in patients infused with oligosaccharides (65.1 +/- 33.2 g/d) than in controls (1.83 +/- 1.55 g/d). Overall oligosaccharide utilization for the 4-d period was 48.7 +/- 10.1%. Plasma oligosaccharide concentrations increased from a baseline value of 2.43 +/- 1.90 mg/dL to 58.1 +/- 42.3 mg/dL after 4 d of oligosaccharide infusion, suggesting accumulation.