Semaphorin3a disrupts podocyte foot processes causing acute proteinuria.

Semaphorin3a was discovered as a secreted guidance protein that acts as a chemorepellent to migrating axons and endothelial cells. In the adult mouse kidney, it is expressed in podocytes and collecting tubules. Here, we show that exogenous semaphorin3a caused acute nephrotic range proteinuria associated with podocyte foot process effacement and fusion, endothelial cell damage, decreased vascular endothelial growth factor-A receptor expression, and downregulation of the slit-diaphragm proteins podocin, nephrin, and CD2-associated protein. When vascular endothelial growth factor 165 was administered at the same time as Semaphorin3a, no proteinuria or renal ultrastructural abnormalities occurred, suggesting that semaphorin3a effects may be mediated, in part, by downregulation of vascular endothelial growth factor receptor 2 signaling. Our findings indicate that a balance of semaphorin3a to vascular endothelial growth factor-A may be important for glomerular filtration barrier homeostasis.

Effects of different fuchsin analogs on the Feulgen reaction.

The Feulgen reaction is used for cytophotometric quantitation of nuclear DNA. Schiff's reagents used in the Feulgen reaction usually are prepared from basic fuchsin, a variable mixture of four triaminotriphenylmethane analogs. The effect of the several fuchsin analogs on the quality of Schiff's staining of hydrolyzed DNA is not known. In this investigation Schiff's reagents prepared from relatively pure fuchsin analogs were used to determine whether different fuchsin analogs affect the absorbance of the Schiff's reagent-DNA complexes formed in solution. It has been determined that the complex formed by pararosaniline-Schiff's reagent and hydrolyzed DNA exhibits lower absorption than do corresponding complexes formed by Schiff's reagents prepared from magenta II or from new fuchsin.

Multimedia to teach urology to medical students.

OBJECTIVES: To test the hypothesis that an interactive multimedia-based computer application may be used to teach urology to undergraduate medical students. METHODS: Third-year medical students rotating on their urology clerkship were studied. Student knowledge was measured with a multiple choice test administered in a pretest-post-test experimental design. The educational intervention was a multimedia-based application that presented a clinical module on hematuria, using natural language-like entries. Student attitudes toward the multimedia application were assessed by a survey. RESULTS: Twenty-three consecutive third-year medical students participated. Mean pretest and post-test scores +/- standard deviation were 35%+/-11% versus 74%+/-17%, respectively, P<0.0001. Student questionnaire responses indicated highly positive opinions that the multimedia-based module was easy to use, was fun, provided natural patient responses, had clear exercises, provided immediate feedback, was educational, and had a nonthreatening format, and that the multiple choice questions were clear and fair. CONCLUSIONS: Multimedia-based education may be used to teach urology to undergraduate medical students.

The malone antegrade continence enema combined with urinary diversion in adult neurogenic patients: early results.

OBJECTIVES: Patients with neurogenic voiding dysfunction often have coexisting neurogenic bowel problems. Impaired bowel evacuation is a cause of major morbidity and impaired lifestyle for these patients. The Malone antegrade continence enema (ACE) performed synchronously with a urinary continence procedure has been successful in pediatric patients. We report early experience combining the ACE with a urinary continence procedure in adult neurogenic patients. METHODS: Adult patients with neurogenic voiding dysfunction and impaired bowel evacuation refractory to conservative management underwent a urinary continence procedure synchronously with an ACE. RESULTS: Two patients have undergone the procedure. One patient chose a continent catheterizable supravesical bladder augmentation, whereas the other patient chose an ileal conduit. Both patients had a separate appendiceal stoma for their ACE. Both patients are continent of stool at their appendiceal stoma and per rectum. Both patients have stabilized their urinary tracts. Complications were minimal. CONCLUSIONS: The ACE may benefit adult patients with impaired bowel evacuation and may be combined with a urinary continence procedure. Further study of the ACE is warranted.

Laparoscopic pelvic lymph node dissection, laparoscopically assisted seminal vesicle mobilization, and total perineal prostatectomy versus radical retropubic prostatectomy for prostate cancer.

OBJECTIVES: The outcomes of patients with prostate cancer who were candidates for radical prostatectomy were compared with patients who underwent either: (1) radical retropubic prostatectomy (RRP); or (2) laparoscopic pelvic lymph node dissection, laparoscopically assisted seminal vesicle mobilization, and total perineal prostatectomy (LN-SV-TPP). METHODS: The staging, surgical, and early postoperative characteristics of 10 consecutive patients treated by RRP were compared with 12 consecutive patients who underwent LN-SV-TPP. RESULTS: Patients who underwent LN-SV-TPP versus RRP had respective median blood loss of 450 versus 1250 cc (P = 0.001), median anesthesia time of 330 versus 287.5 minutes (P = 0.05), median surgical time of 237.5 versus 237.5 minutes (P = 0.6), median units transfused of 0 versus 1 (P = 0.05), median time to ambulation of 1 versus 2 days (P = 0.002), median time to oral intake of 1 versus 3.5 days (P < 0.001), median hospital stay of 3 versus 6 days (P < 0.001), and median morphine requirements of 44 versus 119 mg (P < 0.001). CONCLUSIONS: LN-SV-TPP is less morbid than RRP concerning blood loss, blood transfusions, pain, and postoperative recovery. Compared with LN-SV-TPP, RRP is faster and is particularly indicated for ease of performing a nerve-sparing radical prostatectomy.

Holmium:yttrium-aluminum-garnet lithotripsy efficiency varies with stone composition.

OBJECTIVES: To test the hypothesis that holmium:yttrium-aluminum-garnet (YAG) lithotripsy efficiency varies with stone composition. METHODS: Single pulses of holmium:YAG energy were delivered using 272-, 365-, 550-, and 940-microm optical fibers to human calculi composed of calcium oxalate monohydrate (COM), calcium hydrogen phosphate dihydrate (CHPD), cystine, magnesium ammonium phosphate hexohydrate (MAPH), and uric acid. Energy/pulse settings were 0.2, 0.5, 1.0, and 1.5 J. Stone crater width and depth were characterized with reflectance light microscopy. RESULTS: For similar energies overall MAPH yielded the deepest and widest craters. CHPD, cystine, and uric acid yielded craters of intermediate width and depth. COM yielded the smallest craters. Within any given composition, increased pulse energy yielded craters of increased width and depth. CONCLUSIONS: Holmium:YAG lithotripsy efficiency varies with stone composition. The rank order of crater size appears to correlate with thermal threshold for each composition. Increased holmium:YAG energy produces larger craters for all compositions.

Holmium:yttrium-aluminum-garnet laser cystolithotripsy of large bladder calculi.

OBJECTIVES: Patients with large bladder calculi (4 cm or larger) have traditionally been managed with open cystolithotomy. Endoscopic management with cystolitholapaxy or electrohydraulic lithotripsy risks complications. In an effort to spare patients the morbidity of open cystolithotomy, the results of holmium:yttrium-aluminum-garnet (YAG) laser cystolithotripsy for bladder calculi 4 cm or larger were reviewed. METHODS: Consecutive patients with bladder calculi of 4 cm or larger were managed with holmium:YAG laser cystolithotripsy. Laser energy was delivered using either the 365-micron end-firing fiber or the 550-micron side-firing fiber. RESULTS: Fourteen consecutive patients were managed with holmium:YAG cystolithotripsy. All patients were rendered stone free, regardless of stone composition or size. Median anesthesia time was 57 minutes. Twelve of 14 patients were discharged by the first postoperative day. The procedure times normalized for stone size (mean +/- standard deviation) for the end-firing versus the side-firing fibers were 13 +/- 6 min/cm versus 6 +/- 1 min/cm, respectively; P = 0.04. CONCLUSIONS: Holmium:YAG laser cystolithotripsy of large bladder calculi is effective, technically facile, and safe. The 550-micron side-firing fiber may be better suited for large bladder calculi compared with the 365-micron end-firing fiber. Holmium:YAG cystolithotripsy may obviate open cystolithotomy in selected patients.

Holmium: YAG laser lithotripsy for gallstones. A preliminary report.

BACKGROUND: Most retained gallstones can be extracted at the time of operative exploration or endoscopic retrograde cholangiopancreatography (ERCP). Infrequently, impaction or associated anatomic abnormalities may prevent their clearance. We assessed the efficacy of the holmium:YAG laser in managing retained biliary calculi that had proven refractory to the usual methods of extraction. METHODS: Two patients with calculi impacted in the intrapancreatic common bile duct and one patient with residual stones in a nonfunctional gallbladder were treated with holmium:YAG laser lithotripsy. Two of these patients were treated under conscious sedation, and one received a general endotracheal anesthetic. Laser energy was delivered by a 272-mm optical fiber inserted through a 7-Fr fiberoptic endoscope. The ablative effects were monitored continuously via videoscopic. RESULTS: All of the stones were cleared successfully in a single therapeutic setting. In one patient, fragments of the impacted intraductal stone were extracted with an endoscopic wire basket. In the other two patients, stone debris was completely cleared with saline irrigation. No complications developed, and all patients remained free of recurrence during a 6-month follow-up period. CONCLUSIONS: The holmium:YAG laser is a multidisciplinary instrument that is safe and effective in the fragmentation of both urinary and biliary calculi. Because it can be delivered through a small-caliber fiberoptic endoscope, it should be particularly useful to laparoscopic surgeons who manage complicated biliary tract disease.

Holmium:YAG lithotripsy for large renal and bladder calculi: strategies for efficient lithotripsy.

Holmium:YAG lithotripsy is effective for all stone compositions, and high success rates may be expected. Large renal and bladder calculi may be treated effectively with Ho:YAG lasertripsy. Using angled optical fibers and increasing power settings may be particularly useful to increase lithotripsy speed.

Holmium:YAG laser-induced damage to guidewires: experimental study.

The holmium:YAG laser fragments stones of all compositions effectively. However, damage to ureteral guidewires by the laser has been described, including in one of our own patients, in whom such damage resulted in morbidity. The purpose of this study was to characterize the interaction of Ho:YAG energy with guidewires in vitro. Seven ureteral guidewires were tested in a waterbath. The 365-microm Ho:YAG laser fiber was placed at defined distances (0, 1, 2, 4, and 5 mm) from the guidewire. All guidewires were tested at angles of 0 degrees, 45 degrees, and 70 degrees from normal incidence. The minimum energy setting that resulted in structural damage to the guidewires was detected by endoscopic video monitoring. All guidewires were susceptible to Ho:YAG laser damage at modest energy settings. The energy required to produce visual damage varied inversely with the square of the distance of the laser fiber from the guidewire. At a distance of 5 mm, none of the guidewires was damaged, even at energy settings of 2.8 J (the maximum output from the laser). The energy required to induce guidewire damage varied with the inverse of the cosine of the incident angle. The results demonstrate that no guidewire is immune from Ho:YAG laser damage when the fiber and guidewire are in contact. Caution must be exercised when operating the Ho:YAG laser near a guidewire, and guidewire integrity should be assured by the surgeon. Generally, the energy required to induce guidewire damage exceeded lithotripsy levels at distances >1 mm and with higher incident angles, implying a reasonable margin of safety during ureteroscopy. The pattern of energy thresholds required to induce damage with respect to distance and incident angle suggests that the mechanism of Ho:YAG lithotripsy is thermal.

Holmium: YAG laser damage to ureteral guidewire.

The holmium:yttrium-aluminum-garnet (holmium:YAG) laser effectively fragments urinary calculi of all compositions. Complications have been minimal and mostly attributable to the ureteroscopy as opposed to the laser. We report a case in which the polytetrafluoroethylene (PTFE) coating of a ureteral guidewire was broken with the holmium:YAG laser and remained in the collecting system after the guidewire was removed postoperatively. The patient required cystoscopy to remove the guidewire coating.

A perspective on laser lithotripsy: the fragmentation processes.

This paper describes in simple terms the physics of laser-calculus interactions and introduces a method with which physicians can understand or evaluate the application of any new laser technique for use in lithotripsy or other medical fields. Tissue optical properties and laser parameters govern the mechanism(s) of fragmentation of urinary or biliary calculi. Laser pulse energies for clinical lithotripsy range from Q0 = 20 mJ to 2 J for short-pulsed lasers to long-pulsed lasers, respectively. Lasers with short pulse durations (i.e., less than a few microseconds) fragment calculi by means of shockwaves following optical breakdown and plasma expansion of ionized water or calculus compositions or by cavitation collapse, thus manifesting a photoacoustical effect. Laser-tissue interactions involving dominant photomechanical or photoacoustical effects are usually stress confined. Long-pulsed lasers (i.e., >100 microsec), on the other hand, generate minimal acoustic waves, and calculi are fragmented by temperatures beyond the thresholds for vaporization of calculus constituents, melting, or chemical decomposition.

Holmium: YAG lithotripsy: photothermal mechanism.

OBJECTIVE: A series of experiments were conducted to test the hypothesis that the mechanism of holmium:YAG lithotripsy is photothermal. METHODS AND RESULTS: To show that holmium:YAG lithotripsy requires direct absorption of optical energy, stone loss was compared for 150 J Ho:YAG lithotripsy of calcium oxalate monohydrate (COM) stones for hydrated stones irradiated in water (17+/-3 mg) and hydrated stones irradiated in air (25+/-9 mg) v dehydrated stones irradiated in air (40+/-12 mg) (P < 0.001). To show that Ho:YAG lithotripsy occurs prior to vapor bubble collapse, the dynamics of lithotripsy in water and vapor bubble formation were documented with video flash photography. Holmium:YAG lithotripsy began at 60 microsec, prior to vapor bubble collapse. To show that Ho:YAG lithotripsy is fundamentally related to stone temperature, cystine, and COM mass loss was compared for stones initially at room temperature (approximately 23 degrees C) v frozen stones ablated within 2 minutes after removal from the freezer. Cystine and COM mass losses were greater for stones starting at room temperature than cold (P < or = 0.05). To show that Ho:YAG lithotripsy involves a thermochemical reaction, composition analysis was done before and after lithotripsy. Postlithotripsy, COM yielded calcium carbonate; cystine yielded cysteine and free sulfur; calcium hydrogen phosphate dihydrate yielded calcium pyrophosphate; magnesium ammonium phosphate yielded ammonium carbonate and magnesium carbonate; and uric acid yielded cyanide. To show that Ho:YAG lithotripsy does not create significant shockwaves, pressure transients were measured during lithotripsy using needle hydrophones. Peak pressures were <2 bars. CONCLUSION: The primary mechanism of Ho:YAG lithotripsy is photothermal. There are no significant photoacoustic effects.

Laser lithotripsy and cyanide.

BACKGROUND AND PURPOSE: Holmium:YAG lithotripsy of uric acid calculi produces cyanide. The laser and stone parameters required to produce cyanide are poorly defined. In this study, we tested the hypotheses that cyanide production: (1) varies with holmium:YAG power settings; (2) varies among holmium:YAG, pulsed-dye, and alexandrite lasers; and (3) occurs during holmium:YAG lithotripsy of all purine calculi. MATERIALS AND METHODS: Holmium:YAG lithotripsy of uric acid calculi was done using various optical fiber diameters (272-940 microm) and pulse energies (0.5-1.5 J) for constant irradiation (0.25 kJ). Fragmentation and cyanide were quantified. Cyanide values were divided by fragmentation values, and fragment sizes were characterized. To test the second hypothesis, uric acid calculi were irradiated with Ho:YAG, pulsed-dye, and alexandrite lasers. Fragmentation and cyanide were measured, and cyanide per fragmentation was calculated. Fragment sizes were characterized. Finally, Ho:YAG lithotripsy (0.25 kJ) of purine and nonpurine calculi was done, and cyanide production was measured. RESULTS: Fragmentation increased as pulse energy increased for the 550- and 940-microm optical fibers (P < 0.05). Cyanide increased as pulse energy increased for all optical fibers (P < 0.002). Cyanide per fragmentation increased as pulse energy increased for the 272-microm optical fiber (P = 0.03). Fragment size increased as pulse energy increased for the 272-microm, 550-microm, and 940-microm optical fibers (P < 0.001). The mean cyanide production from 0.25 kJ of optical energy was Ho:YAG laser 106 microg, pulsed-dye 55 microm, and alexandrite 1 microg (P < 0.001). The mean cyanide normalized for fragmentation (microg/mg) was 1.18, 0.85, and 0.02, respectively (P < 0.001). The mean fragment size was 0.6, 1.1, and 1.9 mm, respectively (P < 0.001). After 0.25 kJ, the mean amount of cyanide produced was monosodium urate stones 85 microg, uric acid 78 microg, xanthine 17 microg, ammonium acid urate 16 microg, calcium phosphate 8 microg, cystine 7 microg, and struvite 4 microg (P < 0.001). CONCLUSIONS: Cyanide production varies with Ho:YAG pulse energy. To minimize cyanide and fragment size, Ho:YAG lasertripsy is best done at a pulse energy < or = 1.0 J. Cyanide production from laser lithotripsy of uric acid calculi varies among Ho:YAG, pulsed-dye, and alexandrite lasers and is related to pulse duration. Cyanide is produced by Ho:YAG lasertripsy of all purine calculi.

Free electron laser lithotripsy: threshold radiant exposures.

PURPOSE: To determine the threshold radiant exposures (J/cm2) needed for ablation or fragmentation as a function of infrared wavelengths on various urinary calculi and to determine if there is a relation between these thresholds and lithotripsy efficiencies with respect to optical absorption coefficients. MATERIALS AND METHODS: Human calculi composed of uric acid, calcium oxalate monohydrate (COM), cystine, or magnesium ammonium phosphate hexahydrate (MAPH) were used. The calculi were irradiated in air with the free electron laser (FEL) at six wavelengths: 2.12, 2.5, 2.94, 3.13, 5, and 6.45 microm. RESULTS: Threshold radiant exposures increased as optical absorption decreased. At the near-infrared wave-lengths with low optical absorption, the thresholds were >1.5 J/cm2. The thresholds decreased below 0.5 J/cm2 for regions of high absorption for all the calculus types. Thresholds within the high-absorption regions were statistically different from those in the low-absorption regions, with P values much less than 0.05. CONCLUSIONS: Optical absorption coefficients or threshold radiant exposures can be used to predict lithotripsy efficiencies. For low ablation thresholds, smaller radiant exposures were required to achieve breakdown temperatures or to exceed the dynamic tensile strength of the material. Therefore, more energy is available for fragmentation, resulting in higher lithotripsy efficiencies.

Holmium: YAG lithotripsy: optimal power settings.

PURPOSE: We tested the hypothesis that holmium:YAG laser lithotripsy speed is best maximized by using low pulse energy at high pulse frequency. MATERIALS AND METHODS: To demonstrate that optical fiber damage increases with pulse energy and irradiation, the 365-microm optical fiber irradiated calcium hydrogen phosphate dihydrate (CHPD), calcium oxalate monohydrate (COM), cystine, magnesium ammonium phosphate hexahydrate (MAPH), and uric acid calculi at pulse energies of 0.5 to 2.0 J. Optical energy output was measured with an energy detector after 10 J to 200 J of total energy. To demonstrate that lithotripsy efficiency varies with power, fragmentation was measured at constant power settings at total energies of 200 J and 1 kJ with the 365-microm optical fiber. Fragmentation was measured for the 272-microm optical fiber at pulse energies of 0.5 J to 1.5 J at 10 Hz. To demonstrate that low pulse energy produces smaller fragments than high pulse energy, fragment size was characterized for COM and uric acid calculi after 0.25 kJ of irradiation using the 272-microm to 940-microm optical fibers at 0.5 J to 1.5 J. RESULTS: Damage to the 365-microm optical fiber was greatest for irradiation of CHPD, followed by MAPH, and COM (P<0.001). There was no significant optical fiber damage after cystine and uric acid lithotripsy. For the 365-microm optical fiber and CHPD, fragmentation after 200 J was greatest for pulse energies < or =1.0 J (P< 0.001). For other compositions, fragmentation was not statistically different among the power settings for constant irradiation. No significant difference was noted in fragmentation for any composition at different pulse energies (1.0 v. 2.0 J) for 1-kJ irradiation. However, for all compositions, the calculated lithotripsy speed was greatest at high power settings (P<0.001). For the 272-microm optical fiber, CHPD fragmentation was greatest for the 1.0-J pulse energy. The mean fragment size and relative quantity of fragments > or =2 mm both increased as pulse energy increased. CONCLUSIONS: Optical fiber degradation varies with stone composition, irradiation, and pulse energy. Holmium:YAG lithotripsy speed is maximized with higher power (either increased pulse energy or higher pulse frequency). Because low pulse energy may be safer and yields smaller fragments than high pulse energy, holmium:YAG lithotripsy speed is best increased by using pulse energies < or =1.0 J at a high repetition rate.

Personal finances of urology residents in Canada.

PURPOSE: We examined how Urology residents in Canada manage their personal finances. MATERIALS AND METHODS: A survey instrument was designed to elicit information on demographics, expenses, savings and incomes. The questionnaire was completed by 40 Urology residents attending the 2000 Queen's Urology Exam Skills Training (QUEST) program. RESULTS: Twenty-eight residents (70%) had educational debt (median debt $50 000). Seventeen residents (45%) paid credit card interest charges within the last year. Four residents (10%) maintained an unpaid credit card balance > $7500 at 17% annual interest rate. Twenty-six residents (67%) contributed to Registered Retirement Savings Program (RRSP) accounts. Seventeen residents (44%) contributed to non-RRSP retirement accounts. Nineteen residents (50%) budgeted expenses. Median resident income was $45 000. Thirteen residents (34%) had cash reserves < $250. CONCLUSION: Many residents save little, and incur substantial debt over and above educational loans. Many residents would benefit from instruction concerning prudent financial management. Residents should be informed of the consequences of low saving and high debt.

Nephrolithiasis.

This article covers the diagnosis and management of renal colic. New imaging modalities will be reviewed using evidence-based medicine. The disposition of the patient with renal colic will be addressed. Additionally, special groups with nephrolithiasis will be discussed.

Calculus fragmentation in laser lithotripsy.

The intracorporeal treatment of urinary calculi with lasers is presented, which describes laser-calculus interactions associated with lithotripsy. Reliable fragmentation of calculi with diverse compositions and minimal collateral tissue damage are primarily contingent upon laser parameters (wavelength, pulse duration, and pulse energy) and physical properties of calculi (optical, mechanical, and chemical). The pulse duration governs the dominant mechanism in calculi fragmentation, which is either photothermal or photoacoustical/photomechanical. Lasers with long pulse durations (i.e. > tens of micros) induce a temperature rise in the laser-affected zone with minimal acoustic waves; material is removed by means of vaporization, melting, mechanical stress, and/or chemical decomposition. Short-pulsed laser ablation (i.e. < 10 micros), on the other hand, produces shock waves, and the resultant mechanical energy fragments calculi. Work continues throughout the world to evaluate the feasibility of advanced lasers in lithotripsy and to optimize laser parameters and light delivery systems pertinent to efficient fragmentation of calculi.

T-cell lymphocytic lymphoma involving the prostate presenting as elevated PSA in paraplegia: case report.

The vast majority of cancers that involve the prostate are adenocarcinomas of the duct-acinar secretory epithelium. Other cancers, primarily leukemia and lymphoma, can involve the prostate and lead to an abnormal digital examination or elevated serum prostate specific antigen (PSA). The case discussed is that of a 62 year-old male with T12 complete paraplegia who presented with a persistently elevated PSA and was subsequently diagnosed with T-cell lymphoma involving the prostate. Although rare, leukemia and lymphoma involving the prostate should be included in the differential diagnosis of patients being evaluated for adenocarcinoma of the prostate.