Nanocomposited silicone hydrogels with a laser-assisted surface modification for inhibiting the growth of bacterial biofilm.

Surface and interface modifications of synthetic silicone hydrogels used for wearable and implantable medical devices, e.g. catheters and contact lenses, are critical to overcome their poor mechanical properties and biofouling. In this paper, silica nanoparticles (SiO2 NPs) were incorporated within silicone hydrogels through photo-polymerization. As compared to the silicone hydrogel, the nanocomposited silicone hydrogel shows highly textured microstructures, increased swelling behaviour and improved stiffness. Meanwhile, a hydrophilic surface of silicone hydrogel is important to minimize protein fouling which forms a conditioning layer for the growth of bacterial biofilm. Here, we applied matrix-assisted pulsed laser evaporation (MAPLE) with a pulsed Nd:YAG laser at 532 nm to deposit polyethylene glycol (PEG) on the surface of the nanocomposited silicone hydrogels. The PEG deposited on the nanocomposited silicone hydrogels forms islands at the submicron-scale, which increase with increasing irradiation time (t). The protein adsorption on nanocomposited silicone hydrogel with PEG deposition decreases over 40 ± 2% when t = 2 h. Compared to the commercial silicone catheters, the nanocomposited silicone hydrogel with PEG deposition can reduce the growth of bacteria from 1.20 × 106 CFU cm-2 to 3.69 × 105 CFU cm-2. In addition, the relative cell viabilities of NIH/3T3 mouse fibroblast cells treated using the nanocomposited silicone hydrogels coated with/without PEG were studied. No toxic effect is imposed on the cells. Consequently, the MAPLE process is a controllable, contamination-free technique to modify the surface of silicone hydrogels. We expect that the nanocomposited silicone hydrogels with appropriate surface treatment can be applied in various wearable and implantable medical devices.

Ureteroscopy for pediatric urolithiasis: an evolving first-line therapy.

OBJECTIVES: To present in a retrospective report a contemporary series of patients aged 14 years and younger who were treated for stones with ureteroscopy at our institution from 1991 to 2002. With the improvement and miniaturization of ureteroscopes and ancillary instruments, the endoscopic treatment of renal and ureteral calculi in children has become more feasible. METHODS: A retrospective chart review was performed of 23 patients aged 14 years and younger who had undergone ureteroscopy for the treatment of ureteral or renal calculi at our institution. RESULTS: A total of 27 stones were treated in 23 patients. Of the 27 stones, 18 were in the distal ureter, 5 in the mid ureter, 2 in the proximal ureter, and 2 in the renal pelvis. Ureteral dilation was performed in 4 (17.4%) of the 23 patients. The lithotripsy modalities used were holmium:yttrium-aluminum-garnet laser in 16 (69.6%), electrohydraulic lithotripsy in 3 (13%), a combination of holmium laser and electrohydraulic lithotripsy in 2 (8.7%), and basket extraction alone in 2 (8.7%) of 23 patients. Ureteral stents were placed in 21 (91.3%) of 23 patients. The average operative time was 46.9 minutes (range 15 to 92). In 21 (91.3%) of 23 patients, postoperative imaging was available and revealed that 20 (95.2%) of the 21 patients were rendered stone free. Two patients were lost to follow-up. No intraoperative complications occurred. One patient was treated postoperatively with intravenous antibiotics for transient fever. CONCLUSIONS: Ureteroscopy is safe and effective in the management of ureteral and renal calculi in children. In our institution, it has emerged as a valid first-line therapy for the treatment of pediatric urolithiasis.

Results of shockwave lithotripsy for pediatric urolithiasis.

BACKGROUND AND PURPOSE: Shockwave lithotripsy (SWL) is widely practiced in the management of pediatric urolithiasis. However, the efficacy, need for ancillary procedures, and treatment-related complications are not as clearly defined as in the adult population. We reviewed the outcomes of SWL in the pediatric population at our lithotripsy unit. PATIENTS AND METHODS: A retrospective review of all patients

Lower pole I: a prospective randomized trial of extracorporeal shock wave lithotripsy and percutaneous nephrostolithotomy for lower pole nephrolithiasis-initial results.

PURPOSE: The efficacy of shock wave lithotripsy and percutaneous stone removal for the treatment of symptomatic lower pole renal calculi was determined. MATERIALS AND METHODS: A prospective randomized, multicenter clinical trial was performed comparing shock wave lithotripsy and percutaneous stone removal for symptomatic lower pole only renal calculi 30 mm. or less. RESULTS: Of 128 patients enrolled in the study 60 with a mean stone size of 14.43 mm. were randomized to percutaneous stone removal (58 treated, 2 awaiting treatment) and 68 with a mean stone size of 14.03 mm. were randomized to shock wave lithotripsy (64 treated, 4 awaiting treatment). Followup at 3 months was available for 88% of treated patients. The 3-month postoperative stone-free rates overall were 95% for percutaneous removal versus 37% lithotripsy (p <0.001). Shock wave lithotripsy results varied inversely with stone burden while percutaneous stone-free rates were independent of stone burden. Stone clearance from the lower pole following shock wave lithotripsy was particularly problematic for calculi greater than 10 mm. in diameter with only 7 of 33 (21%) patients becoming stone-free. Re-treatment was necessary in 10 (16%) lithotripsy and 5 (9%) percutaneous cases. There were 9 treatment failures in the lithotripsy group and none in the percutaneous group. Ancillary treatment was necessary in 13% of lithotripsy and 2% percutaneous cases. Morbidity was low overall and did not differ significantly between the groups (percutaneous stone removal 22%, shock wave lithotripsy 11%, p =0.087). In the shock wave lithotripsy group there was no difference in lower pole anatomical measurements between kidneys in which complete stone clearance did or did not occur. CONCLUSIONS: Stone clearance from the lower pole following shock wave lithotripsy is poor, especially for stones greater than 10 mm. in diameter. Calculi greater than 10 mm. in diameter are better managed initially with percutaneous removal due to its high degree of efficacy and acceptably low morbidity.

Randomized trial of 10 mL and 20 mL of 2% intraurethral lidocaine gel and placebo in men undergoing flexible cystoscopy.

PURPOSE: To determine if 20 mL of 2% intraurethral lidocaine gel is superior to 10 mL of 2% lidocaine or sterile lubricant for flexible cystoscopy in men. PATIENTS AND METHODS: A randomized, double-blind, placebo-controlled trial was conducted. Sixty men scheduled to undergo diagnostic flexible cystoscopy were randomized to receive either 20 mL of placebo gel (Group I), 10 mL, of 2% lidocaine gel (Group II) or 20 mL of 2% lidocaine gel (Group III). A penile clamp was applied for 15 minutes to ensure consistent indwelling time in all patients. Patients recorded their pain on a 10-cm non-graphical visual analog scale prior to cystoscopy as a baseline, during the procedure, and immediately after the procedure. Patients also recorded their pain and willingness to have the same anesthetic on a 4-point descriptive scale. Heart rate and mean arterial blood pressure (MAP) were recorded at specific intervals throughout the procedure, and increases in mean arterial pressure were considered objective evidence of patient pain. RESULTS: Pain perception was not statistically different in the groups (Group I 4.65, Group II 3.93, Group III 3.57; P = 0.406). Pain assessment and willingness to have the same anesthetic also did not differ statistically among the groups. Similarly, differences in the increases in MAP were not statistically significant between groups. CONCLUSION: Instillation of 20 mL or 10 mL of 2% lidocaine gel has no advantage over plain lubricant in providing anesthesia for flexible cystoscopy in men.

Serum biochemical changes after laparoscopy may be indicators of bladder injury.

We evaluated the serum renal biochemical profile as an indicator of unrecognized laparoscopic bladder injury in four women. The patients were seen 24 to 56 hours postoperatively with elevated serum creatinine and urea levels, and electrolyte changes compatible with acute renal dysfunction. The mechanism responsible for these biochemical changes appears to be extravasation and reabsorption of urine. Biochemical values returned to normal within 24 hours after bladder repair.

A prospective randomized controlled trial comparing nonstented versus stented ureteroscopic lithotripsy.

PURPOSE: A prospective randomized controlled trial was performed to determine whether stents may be eliminated after uncomplicated ureteroscopic lithotripsy for ureteral stones. MATERIALS AND METHODS: A total of 58 patients underwent uncomplicated ureteroscopic intracorporeal lithotripsy. After stone fragmentation patients were randomized to a nonstented (29) or a stented (29) treatment group. Intracorporeal lithotripsy was performed with the holmium laser in 57 cases and by electrohydraulic lithotripsy in 1 without balloon dilation or the extraction of stone fragments. Patients were followed 1, 6 and 12 weeks postoperatively. In stented cases the stent was removed at 1 week. Outcome measures included postoperative symptoms assessed with a visual analog scale, postoperative analgesic requirements, complications and the stone-free rate. RESULTS: At 1 week the symptoms of flank pain, abdominal pain, dysuria and frequency were significantly greater in the stented group (p <0.005). There were no differences in symptoms in the groups at subsequent followup visits. There was no difference in treatment groups in terms of the amount of analgesic required in the recovery room or during 1 week after ureteroscopy. Similarly there was no difference in the number of patients requiring antiemetics. One patient in the stented group required hospitalization for genitourinary sepsis and 1 patient in the nonstented group visited the emergency room for postoperative vomiting. The stone-free rate was 100% in each group. CONCLUSIONS: These results demonstrate that after ureteroscopic intracorporeal lithotripsy with the holmium laser patients with a stent have significantly greater irritative and painful symptoms than those without a stent in the early postoperative period. There was no difference in nonstented and stented ureteroscopy with respect to complications or stone-free status. Therefore, we believe that routine stenting after ureteroscopic intracorporeal lithotripsy with the holmium laser is not required as long as the procedure is uncomplicated and performed without balloon dilation of the ureteral orifice.

Stray radiofrequency current as a cause of urethral strictures after transurethral resection of the prostate.

PURPOSE: This study was designed to define the pattern and significance of stray currents induced by two electrosurgical generators (ESGs) in relation to urethral strictures forming after transurethral resection of the prostate (TURP). MATERIALS AND METHODS: A 24F resectoscope irrigated with glycine was activated at various power outputs in different modes, with intact loops and loops with faulty insulation, simulating TURP. The Valleylab and ERBE ESGs were compared for inducing capacitance. An ESG analyzer simulated tissue impedance and recorded the stray currents induced along the resectoscope sheath. A fresh pig liver was used for assessment of tissue damage caused by the currents. RESULTS: In the cutting mode, the ERBE ESG produced a mean stray current of 70 mA with an intact loop and 144 mA with a loop having faulty insulation. The Valleylab ESG produced 150 mA and 161 mA, respectively. In the coagulation mode, the ERBE ESG produced an average leakage current of 35 mA and, with a loop with faulty insulation, 40 mA. The Valleylab ESG produced 148 mA and 151 mA, respectively. CONCLUSIONS: Electrical injury may represent a significant cause of urethral stricture after transurethral electrosurgery. The critical power density of 7.5 W/cm2 (which is likely to cause a urethral burn) may be reached, especially with the use of loops with faulty insulation or nonconductive lubricating gel. The ERBE ESG produced significantly less capacitance, decreasing the risk of urethral electrical burn. Conductive gel prevents dangerous current concentration.

Oral fluoroquinolone therapy results in drug adsorption on ureteral stents and prevention of biofilm formation.

The oral administration of ciprofloxacin (250mg bid) and ofloxacin (300mg bid) in 40 patients with ureteral stents, led to drug levels on all the device surfaces that were higher than the minimum inhibitory concentration (MIC) of Escherichia coli (0.004--0.015 mg/l), the most common uropathogen. The drug levels in the film were higher than the MIC of other common pathogens, namely Pseudomonas aeruginosa (0.25--1.0 mg/l), Enterococcus faecalis (0.25--2.0 mg/l) and Staphylococcus aureus (0.12--0.5 mg/l) in a few cases (six, three and 14 cases out of 40, respectively). For both antibiotics, the concentrations were greater than the MIC of many uropathogens on the film surrounding the devices (0.89 vs 0.31 mg/l respectively, P=0.05), and on the devices themselves (0.22 vs. 0.12 mg/l, P=0.207). Adsorption of the antibiotics was higher to the film than to the stent (P<0.0001). Ciprofloxacin concentration on the film surrounding the stents was significantly higher than that of ofloxacin (P=0.05), while there was no statistical concentration difference between the two antibiotics adsorbed onto the actual devices (P=0.207). No bacteria were found in patients' urine and no biofilms were detected. This is the first report of an oral antibiotic being adsorbed onto medical devices. It potentially provides a new approach of preventing infection, and avoids the need to pre-coat devices with agents whose use will be restricted once bacteria develop resistance to them. If biomaterial properties can be enhanced to increase further the adsorptive concentration of drug, the risk of infections and recalcitrant biofilm formation could be significantly reduced in a highly susceptible patient population.

Imaging and the Internet.

Internet-based imaging is changing the way urology services are delivered by allowing rapid communication between remote locations. This review focuses on Internet-based imaging modalities, the hardware needed to transmit and view these images, and current applications. With the continuing expansion of Internet-based resources, all physicians must become accustomed to integrating the Internet and Internet-based imaging into their practices.

Flexible ureteroscopy and lithotripsy with the Holmium: YAG laser.

Extracorporeal shock wave lithotripsy (ESWL), Dornier Medical Systems, remains the main form of therapy for most urinary stones. The minimally invasive nature of ESWL makes it an attractive form of therapy to both patients and physicians. Many patients however may be most effectively managed by an endoscopic procedure either percutaneously or by transurethral ureteroscopy. Recent years have seen considerable advancement in endoscope technology such that flexible, actively deflectable ureteroscopes of 7.5 F or smaller in diameter have become available for performing upper tract endoscopy. When combined with new intracorporeal lithotripsy devices such as the Holmium:YAG laser, urologists have an effective alternative to ESWL for many stone problems. In this article we review our technique of flexible ureteroscopy combined with Holmium:YAG laser lithotripsy.

Advances in ureteral stent technology.

This review focuses on technological advances and relevant research related to ureteral stents. The importance of physical and chemical biomaterial type, biocompatibility, material coatings such as hydrogels, and infection related to indwelling ureteral stents are discussed. Recent in vitro and in vivo research has focused on materials that will reduce encrustation and bacterial biofilm formation. The adsorption of antimicrobials onto devices holds promise of reducing infection rates, but multidrug resistant bacteria, short leaching times and adverse side effects make it essential that alternative strategies be investigated. Just so, encrustation limits the long-term use of urinary materials, and a better understanding of factors involved in encrustation are needed to reduce the problem.

Treatment of caliceal diverticular stones: transdiverticular percutaneous nephrolithotomy with creation of a neoinfundibulum.

PURPOSE: To evaluate transdiverticular percutaneous nephrolithotomy (TDPN) with creation of a neoinfundibulum in the treatment of caliceal diverticular stones. PATIENTS AND METHODS: Between 1990 and 1998, 18 patients with symptomatic calculi in caliceal diverticula underwent TDPN. Transdiverticular puncture into the renal collecting system with creation of a neoinfundibulum was used, eliminating the need for prolonged probing with a wire for the neck of the diverticulum. Eight diverticula were upper polar, six were interpolar, and four were in the lower pole. Stones were endoscopically treated with use of Lithoclast (Electromedical Systems, Lausanne, Switzerland), graspers, ultrasound, or a combination of these methods. RESULTS: Sixteen kidneys (89%) were rendered stone-free at discharge. Two kidneys (11%) were left with stone fragments of 5 mm or smaller. Hospital stay ranged from 3 to 15 days (average, 7 days). Procedure time ranged from 45 to 169 minutes (average, 87 minutes). One patient developed a left renal-pleural fistula, which closed 1 week after chest tube drainage. No other complications were encountered for an overall complication rate of 6%. CONCLUSION: TDPN is a safe and effective method for treating caliceal diverticular stones, with a complication rate comparable to other methods.

Electrical burn of urethra as cause of stricture after transurethral resection.

BACKGROUND AND PURPOSE: One of the most common complications of transurethral resection is urethral stricture. The exact etiology is still controversial. Postulated pathophysiology ranges from mechanical trauma to the urethra during the resection to inflammatory reaction secondary to local anesthesia. We propose electrical burn to the urethra as a contributory factor in some cases. MATERIALS AND METHODS: Electrical events during transurethral resection were simulated in vitro. The distribution of current was measured at the loop/rollerball and in the outer metal sheath. Both an intact loop/rollerball and loop/rollerball with faulty insulation were tested. Various power outputs simulating coagulation, cutting, and vaporization were used. Data were recorded both in settings where the outer metal sheath was and was not smeared with nonconductive lubricating gel. RESULTS: Approximately 20% of the total current output was shunted to the metal sheath when an intact loop/rollerball was used. One hundred percent of the current was short-circuited to the sheath when a loop/rollerball with faulty insulation was retracted into the sheath. Little current was detectable in the nonconductive lubricating gel. We then calculated the length of time required, in various settings, to reach tissue temperature of 45 degrees C, when protein denaturation starts. The higher the power output and the smaller the contacting surface area, the more likely it is for urethral burns to occur. CONCLUSION: Our in vitro experiment showed that urethral burns secondary to stray current in the resectoscope sheath are unlikely when an intact loop is used. However, urethral burns can occur when a loop/rollerball with faulty insulation is used, especially in combination with nonconductive gel that is dispersed unevenly within the urethra.

Intracorporeal lithotripsy. Update on technology.

The number and variety of devices currently available for endoscopic lithotripsy reflect the reality that no single device is ideal in all situations. Although the search for the universal lithotriptor continues, the urologist must consider several factors if faced with the decision of which device to purchase. Perhaps foremost among these factors is the clinical situation with which one commonly deals. For example, although the smaller, flexible probes such as EHL or laser demonstrate considerable utility if used ureteroscopically, the larger stone burden associated with today's percutaneous nephrolithotripsy population often is treated more efficiently with one of the mechanical devices employing a larger, rigid probe, such as ultrasound or the Lithoclast. Similarly, the type and size of endoscopic equipment at one's disposal have a significant impact on which device to purchase or use. There are physical constraints affecting which device may or may not be used, rigid versus flexible endoscope, working channel caliber, and offset versus end-on-port. The skill and experience of the surgeon is also a factor of obvious importance, particularly if one is using a modality with a relatively narrow margin of safety such as EHL. Likewise, the training and experience of nursing personnel is a factor, especially regarding the use of lasers, which require certified personnel who are well versed in laser safety. Finally, in today's environment one must carefully evaluate cost in terms of not only initial capital outlay but also ongoing charges for disposable and maintenance items. Thus, the decision of which device to purchase is complex and requires careful evaluation of all of the previously noted variables. Likewise, if one is fortunate enough to have more than one device available, the decision of which lithotriptor to employ requires a similar decision based on sound surgical judgment.

Intended and stray radiofrequency electrical currents during resectoscopic surgery.

STUDY OBJECTIVE: To test the hypothesis that electrical burns of the genital tract and urethral strictures after hysteroscopic endometrial ablation and transurethral prostatectomy, respectively, are related to capacitive coupling and/or stray currents induced by intact and defective electrodes and/or resectoscopes. DESIGN: Basic in vitro measurements. SETTING: Laboratory. MATERIALS: Porcine muscle and liver, resectoscope, electrosurgical unit (ESU), and ESU analyzer. INTERVENTION: We measured electrical coagulation and cutting currents of rollerball and loop electrodes and the external sheath of the resectoscope from 80 to 200 W through a resistance load of 200 and 250 ohms, using intact electrodes and conditions simulating potential insulation defects along the shaft of the electrodes. MEASUREMENTS AND MAIN RESULTS: Approximately 20% to 25% of current was induced by capacitive coupling to the resectoscope sheath. Touching porcine muscle or liver with small areas of the sheath while the generator was activated resulted in superficial tissue burn. Surrounding large segments of the sheath with tissue did not result in visible burns, indicating that under normal conditions the sheath acts as a dispersive electrode. Defective insulation of distal segments of the electrodes resulted in 100% transfer of current to the sheath and caused extensive electrical burns of tissue in contact with the sheath. CONCLUSIONS: Capacitive coupled currents induced by intact resectoscopes and electrodes may cause thermal injury to surrounding tissue during prolonged resectoscopic surgery. Stray currents from defective insulation of the electrodes result in direct coupling of current to the telescope and sheath and cause extensive burns of surrounding tissues in contact with the sheath.

Encrustation of biomaterials in the urinary tract.

The present review focuses on technological advances and relevant research related to encrustation of biomaterials in the urinary tract. The importance of physical and chemical biomaterial type, biocompatibility, material coatings such as hydrogels, and infection related to alloplastic materials used in urological practice are discussed. Recent in-vitro and in-vivo research has focused on materials that will reduce encrustation and bacterial biofilm formation, complications that limit the long-term use of urinary materials. Coordinating scientific resources in a multidisciplinary manner for a better understanding of factors that are involved in encrustation and biofilm formation will offer the potential to modify or resolve the problem of encrustation of foreign materials in the urinary tract.