Dependence of laser-induced tissue ablation on optical fiber movements for laser prostatectomy.

PURPOSE: The aim of the current study was to identify the efficient fiber movements for 532-nm laser prostatectomy. MATERIALS AND METHODS: 532-nm Lithium triborate (LBO) laser light was tested on 120 kidney tissues at three different translational speeds (TS 1, 2, and 4 mm/s) and four different rotational speeds (RS 0.5, 1.0, 1.6, and 2.1 rad/s). The applied power was 120 W at a 2-mm working distance and 60° sweeping angle. Ablation rate and dimensions of resulting ablation craters were measured. RESULTS: Slower TSs and RSs created deeper and wider ablation craters with thinner coagulation, leading to more efficient ablation performance. Maximal ablation rate was achieved at a TS of 2 mm/s and RSs of 0.5 and 1.0 rad/s. An RS of 0.5 rad/s accompanied surface carbonization for all the TSs. Irrespective of TS, ablation rate became saturated at faster RSs than 1.0 rad/s. Faster TSs or RSs reduced tissue ablation, but increased thermal coagulation due to a shorter interaction time. CONCLUSIONS: Optimal ablation efficiency occurred at a TS of 2 mm/s and a RS of 1.0 rad/s with a thin coagulation of around 1.0 mm and no or minimal carbonization. Further studies will validate the current findings with prostate tissue and high-power levels for laser prostatectomy.

A Urinary Drug-Disposing Approach as an Alternative to Intravesical Chemotherapy for Treating Nonmuscle Invasive Bladder Cancer.

The standard treatment of nonmuscle invasive bladder cancer (NMIBC) is transurethral resection of the tumors, followed by intravesical therapy (IT), which comprises a direct instillation of a solution of Bacillus Calmette-Guérin vaccine or chemotherapy into the bladder. However, the recurrence rate in this disease remains unacceptably high. IT is a local treatment that fails to reach tumors developed in the upper urinary tract (ureter and renal pelvis). The catheterization procedure required for IT is invasive, painful, and poses an increased infection risk, resulting in poor patient quality of life and compliance. There is an unmet need for a potent, comprehensive, and noninvasive option. Without chemical modifications, peptides are rapidly removed by renal clearance. This "shortcoming" can be advantageous when used as a drug carrier for directing therapy to NMIBC. Here we develop a urinary drug-disposing (UDD) approach to improve NMIBC treatment. A 12-amino acid bio-inert peptide (Bdd) that can be exclusively eliminated via renal filtration was generated for delivering the microtubule inhibitor DM1 to NMIBC with minimal nonspecific accumulation in other organs. The UDD approach prolonged survival of mice bearing human bladder tumors. Unlike IT, the treatment was given noninvasively (intravenously). Furthermore, it was more effective at suppressing tumor growth than clinically used IT (mitomycin) and safer than free DM1. The application of this UDD approach to treat kidney tumors and deliver other drugs such as doxorubicin was also demonstrated. Overall, the rapid renal clearance of peptides can be exploited to direct cancer therapies to the urinary system. SIGNIFICANCE: A noninvasive drug delivery approach that targets the urinary system overcomes the current barriers facing effective treatment of bladder cancer.

Review of Power Electronics Components at Cryogenic Temperatures.

In order to apply power electronics systems to applications such as superconducting systems under cryogenic temperatures, it is necessary to investigate the characteristics of different parts in the power electronics systems. This paper reviews the influence of cryogenic temperature on power semiconductor devices including Si and wide bandgap switches, integrated circuits, passive components, interconnection and dielectric materials, and some typical cryogenic converter systems. Also, the basic theories and principles are given to explain the trends for different aspects of cryogenically cooled converters. Based on the review, Si active power devices, bulk CMOS based integrated circuits, nanocrystalline and amorphous magnetic cores, NP0 ceramic and film capacitors, thin/metal film and wirewound resistors are the components suitable for cryogenic operation. Pb-rich PbSn solder or In solder, classic PCB material, most insulation papers and epoxy encapsulant are good interconnection and dielectric parts for cryogenic temperatures.

Review of current laser therapies for the treatment of benign prostatic hyperplasia.

The gold standard for symptomatic relief of bladder outlet obstruction secondary to benign prostatic hyperplasia has traditionally been a transurethral resection of the prostate (TURP). Over the past decade, however, novel laser technologies that rival the conventional TURP have multiplied. As part of the ongoing quest to minimize complications, shorten hospitalization, improve resection time, and most importantly reduce mortality, laser prostatectomy has continually evolved. Today, there are more variations of laser prostatectomy, each with several differing surgical techniques. Although abundant data are available confirming the safety and feasibility of the various laser systems, future randomized-controlled trials will be necessary to verify which technique is superior. In this review, we describe the most common modalities used to perform a laser prostatectomy, mainly, the holmium laser and the potassium-titanyl-phosphate lasers. We also highlight the physical and clinical characteristics of each technology with a review of the most current and highest-quality literature.

A retrospective review of office-based 532-nm GreenLight laser prostatectomy in men with symptomatic benign prostatic hyperplasia.

OBJECTIVE: To evaluate the feasibility, safety, and outcomes of men with symptomatic benign prostatic hyperplasia undergoing 532-nm GreenLight laser prostatectomy in the office-based setting. MATERIALS AND METHODS: From September 2007 to October 2011, 47 patients underwent office-based 532-nm GreenLight laser prostatectomy by a single surgeon. Patients were enrolled prospectively and preoperative, intraoperative, and postoperative parameters were then reviewed retrospectively. Statistical analysis was performed with Wilcoxon rank sum test with a P value ≤.05 being considered statistically significant. RESULTS: The mean patient age was 66 (range, 49-89); 91% of men were on an alpha-blocker preoperatively; mean (standard deviation; SD) prostate volume by transrectal ultrasound was 35.8 mL (14.5); mean (SD) American Society of Anesthesiologists score was 2.33 (0.77); mean (SD) operative time was 36.73 minutes (18); mean (SD) lasing time was 19.1 minutes (8.31); mean (SD) total laser kiloJoules used was 85,387 kJ (38,885); and mean (SD) follow-up time was 8.48 months (8.24). The 1-year decrease in mean (SD) American Urologic Association Symptom Score and quality of life were 17.7 (8.3)-7 (7.3) and 4.1 (1.4)-2.27 (2) respectively. The maximal urinary flow increased from 8.1 (3.8) to 10.7 (6). Patients' postvoid residual improved from 130 mL (147) to 27 mL (55) over a 1-year period. (P <.01 for all). There were no reoperations for refractory lower urinary tract symptoms or hospital admissions. CONCLUSION: For men with small but symptomatic benign prostatic enlargement, office-based GreenLight laser prostatectomy is safe and feasible.

Defining optimal laser-fiber sweeping angle for effective tissue vaporization using 180 W 532 nm lithium triborate laser.

PURPOSE: The goal of this study is to identify the most efficient sweeping angle (SA) during photoselective vaporization of the prostate (PVP). MATERIALS AND METHODS: Experiments were conducted with GreenLight XPS™ laser at 120 and 180 W. Ten blocks of porcine kidney were used for each SA (0, 15, 30, 45, 60, 90, and 120 degrees). Vaporization efficiency was assessed by the amount of tissue removed per time. The coagulation zone (CZ) thickness was also measured. RESULTS: Maximal vaporization rate (VR) was achieved at SA 15 and 30 degrees. Irrespective of power, VR increased and CZ decreased linearly with decreasing SA from 120 to 30 degrees. The CZ was the thinnest at SA 30 degrees. CONCLUSIONS: Optimal vaporization occurred at a SA of 15 degrees and 30 degrees with the lowest CZ at 30 degrees. Contrary to a previous recommendation for a wider SA (60 degrees or greater), a narrower SA (30 degrees) achieved the maximal tissue vaporization efficiency.

180-W XPS GreenLight laser therapy for benign prostate hyperplasia: early safety, efficacy, and perioperative outcome after 201 procedures.

BACKGROUND: Photoselective vaporisation of the prostate has evolved from the GreenLight 80-W KTP powered laser to the latest 180-W XPS laser involving a MoXy fibre. OBJECTIVE: Evaluate the prevalence of perioperative complications and short-term outcome for the first time with the XPS laser in men with lower urinary tract symptoms (LUTS) due to benign prostatic enlargement (BPE). DESIGN, SETTING, AND PARTICIPANTS: Prospective data were collected from consecutive patients at seven centres worldwide during June 2010 and March 2011. Indication for surgery was based on the European Association of Urology and the American Urological Association guidelines. Patients receiving anticoagulants or those with retention were included and analysed separately. INTERVENTION: 180-W XPS GreenLight laser prostatectomy using the MoXy fibre. MEASUREMENTS: Standard parameters associated with transurethral prostate surgery and perioperative prevalence of surgery-associated problems or complications were documented. RESULTS AND LIMITATIONS: A total of 201 patients were included in the study. Mean follow-up was 5.8 mo (standard deviation [SD]: 2.8; range: 1-12 mo). A quarter of the patients had a prostate volume≥80 ml. For prostates between 51 and 60 ml, a mean of 300 kJ (SD: 112) of energy was applied (lasing time: 35.0 min; SD: 15). Statistically significant improvements were noted in all key parameters postoperatively. The prevalence of perioperative complications was low. Limitations of the study are short duration of follow-up and limited number of available patients for the functional follow-up. CONCLUSIONS: The 180-W GreenLight XPS laser is a new effective treatment option with a low prevalence of perioperative complications for patients suffering from LUTS due to BPE.

Optimal laser fiber rotational movement during photoselective vaporization of the prostate in a bovine ex-vivo animal model.

BACKGROUND AND PURPOSE: Photoselective vaporization of the prostate (PVP) has emerged as an effective debulking procedure for prostatic urinary obstruction. Surgical technique for the most efficient vaporization has, however, received little scientific investigation. We used an ex-vivo bovine prostate model to investigate how variation in the angle of laser fiber rotational movement ("sweeping") affects prostate tissue vaporization efficiency. MATERIALS AND METHODS: Experiments were conducted using the GreenLight™ HPS 120W laser system. A single surgeon performed a clinical PVP video analysis, forming the basis of our study design. Sixty bovine prostate specimens were vaporized using an ex-vivo chamber equipped with computer-assisted axial movements. Specimens were vaporized at a fixed sweeping speed (0.5 sweeps/sec) and variable sweeping angles (0, 15, 30, 60, 90, and 120 degrees). The volume of tissue vaporized was calculated from cross sections and compared by a two-sample t test. RESULTS: Clinical PVP video analysis of a single experienced surgeon showed a mean angle of 47.7 degrees with 25% of vaporization between 0 and 30 degrees. Ex-vivo analysis showed larger sweeping angles generated wider but more superficial vaporization defects, leading to smaller vaporized volumes. Specifically, vaporization volumes with angles of 0, 15, or 30 degrees were significantly greater than those with rotational angles of 45, 60, and 90 degrees (1.5-3.0 X; P<0.05). The depth of tissue coagulation significantly increased with greater rotational angles. CONCLUSIONS: Optimal PVP occurred at narrower angles of laser fiber sweeping in our ex-vivo model. Our findings highlight that PVP laser fiber movement can be tested in a scientific manner, identifying parameters to maximize vaporization efficiency.

The effect of laser-fiber sweeping speed on the efficiency of photoselective vaporization of the prostate in an ex vivo bovine model.

INTRODUCTION: Recommendations for efficient photoselective vaporization of the prostate (PVP) include a side-to-side rotational laser-fiber "sweeping" motion, yet scientific study of this technique is lacking. We investigated whether the speed of laser-fiber sweeping affects tissue vaporization efficiency. METHODS: PVP was performed using the 120-W GreenLight high-performance system. Video analysis of a surgeon performing PVP was carried out to identify sweeping speeds used clinically. PVP efficiency was subsequently tested at four different sweeping speeds using two manipulations of an ex vivo bovine prostate model, including (1) excised prostate tissues (n = 40) in a vaporization chamber equipped with motorized laser-fiber movements; (2) retrograde endoscopic vaporization (n = 80) within whole lower urinary tracts. Vaporized cavity sizes and coagulative margins were measured by liquid-paraffin molding and histologic cross-sectioning approaches. RESULTS: Video analysis of clinical PVP showed wide variability in sweeping speed, mostly ranging between 0.5 and 2.0 (mean 1.50) sweeps/second. Using either manipulation of the ex vivo bovine prostate model described above, PVP at lower sweeping speeds (0.5 and 1.0 sweeps/second) removed significantly more tissue (up to twofold) compared with higher sweeping speeds (1.5 and 2.0 sweeps/second), with significant albeit minimal reductions in coagulation margins. CONCLUSION: In this ex vivo prostate model, our results suggest that vaporization efficiency is compromised with faster laser-fiber sweeping. This finding counters principles of traditional transurethral resection of the prostate, in which faster axial movement toward the surgeon removes tissue more efficiently. This study highlights that PVP technique can be tested in a scientific manner, identifying optimal parameters for achieving maximal tissue vaporization efficiency.

Births using sperm retrieved via immediate microdissection of a solitary testis with cancer.

OBJECTIVE: To determine the feasibility of achieving births using sperm retrieved from a solitary testis with cancer. DESIGN: Prospective clinical study of azoospermic men with testis cancer in a solitary testis. SETTING: Infertility patients in an academic environment. PATIENT(S): Azoospermic men with previous history of orchiectomy and testis cancer in a remaining solitary testis. INTERVENTION(S): Viable sperm were retrieved by immediate microdissection of paratumor testicular tissue from orchiectomy specimen. MAIN OUTCOME MEASURE(S): Live births were achieved using sperm from immediate microdissection of orchiectomy specimen with testis cancer. CONCLUSION(S): Azoospermic men with cancer in a solitary testis have potential for fertility.

A rare case of painless gross hematuria: primary localized AA-type amyloidosis of the urinary bladder.

A 60-year-old Asian woman presented with a 1-year history of painless gross hematuria. She had no prior urologic history and no other medical problems. Her physical examination, urine cytology, and computed tomography scan were normal. Cystoscopy demonstrated several punctate areas of erythema within the bladder. Biopsies revealed amyloidosis, and immunohistochemical staining of the specimens defined the process as amyloid AA (often called secondary amyloidosis). The workup for systemic conditions associated with amyloid AA was negative. This represents an unusual case of primary localized AA-type amyloidosis of the bladder.