Pulse modulation with Moses technology improves popcorn laser lithotripsy.

PURPOSE: Moses™ technology has been developed to improve holmium laser fragmentation at 1-2 mm distance from the stone. Because popcorn lithotripsy is a non-contact technique, we compared short pulse (SP) and Moses distance (MD) modes in an in vitro model. METHODS: BegoStones were fragmented using a 120 W Ho:YAG laser (P120 Moses) and a 230 µm core fiber introduced through a ureteroscope. 20 W (1 J × 20 Hz; 0.5 J × 40 Hz) and 40 W (1 J × 40 Hz; 0.5 J × 80 Hz) settings (total energy 4.8 kJ) were tested using SP and MD modes. We assessed fragment size distribution and mass lost in fluid (initial mass-final dry mass of all sievable fragments). High-speed video analysis of fragmentation strike rate and vapor bubble characteristics was conducted for 1 J × 20 Hz and 0.5 J × 80 Hz. Laser strike rate (number of strikes divided by frequency) was categorized as: (1) direct-a visual plume of dust ejected from stone while in contact with fiber tip; (2) indirect-a visual plume of dust ejected with distance between stone and fiber tip. RESULTS: For 1 J × 20 Hz (20 W), MD resulted in more mass lost in fluid and a lower distribution of fragments ≥ 2 mm compared to SP (p < 0.05). 0.5 J × 80 Hz (40 W) produced no fragments ≥ 2 mm, and there were no significant differences in fragment distribution between MD and SP (p = 0.34). When using MD at 1 J × 20 Hz, 96% of strikes were indirect vs 61% for SP (p = 0.059). In contrast to the single bubble of SP, with MD, there was forward movement of the collapsing second bubble, away from the fiber-tip. CONCLUSIONS: For lower frequency and power popcorn settings, pulse modulation results in more fragmentation through true non-contact laser lithotripsy.

Burnback: the role of pulse duration and energy on fiber-tip degradation during high-power laser lithotripsy.

High-power holmium lasers have become popular for ureteroscopic laser lithotripsy and dusting. Our aim was to investigate the effect of pulse duration and pulse energy on fiber-tip degradation when using high-power settings for popcorn lithotripsy. BegoStones were fragmented in a glass bulb to simulate renal calyx, using a 120 W Ho:YAG laser. A 242 µm fiber was placed via the ureteroscope 2 mm distance from stones (popcorn model). To assess the effect of pulse duration on fiber-tip degradation, long pulse (LP) and short pulse (SP) settings were compared at settings of 1.0Jx20Hz (20 W), 0.5Jx70Hz (35 W), and 1.0Jx40Hz (40 W). To assess the effect of pulse energy on tip degradation, 40 W SP settings (0.5Jx80Hz, 0.8Jx50Hz, and 1.0Jx40Hz) were tested. Pulse duration was measured using a photodetector and peak power was then calculated using the pulse duration and pulse energy. Experiments were conducted for 4 min. Fiber-tip length was measured before and after using a digital caliper. Fiber-tip degradation was least when using LP for all settings tested (p < 0.01). For 40 W settings, tip degradation was significantly lower when using a pulse energy of 0.5 J compared to 0.8 J or 1.0 J (p < 0.004). LP mode results in less fiber burnback for all power settings tested. Total power is more important than frequency in the development of burnback. However, high-power 40 W settings can be utilized with less burnback if lower pulse energies are used. Understanding these parameters can improve the longevity of the laser fiber and improve procedural efficiency.

pADP-ribosylation regulates the cytoplasmic localization, cleavage, and pro-apoptotic function of HuR.

HuR (ElavL1) is one of the main post-transcriptional regulators that determines cell fate. Although the role of HuR in apoptosis is well established, the post-translational modifications that govern this function remain elusive. In this study, we show that PARP1/2-mediated poly(ADP)-ribosylation (PARylation) is instrumental in the pro-apoptotic function of HuR. During apoptosis, a substantial reduction in HuR PARylation is observed. This results in the cytoplasmic accumulation and the cleavage of HuR, both of which are essential events for apoptosis. These effects are mediated by a pADP-ribose-binding motif within the HuR-HNS region (HuR PAR-binding site). Under normal conditions, the association of the HuR PAR-binding site with pADP-ribose is responsible for the nuclear retention of HuR. Mutations within this motif prevent the binding of HuR to its import factor TRN2, leading to its cytoplasmic accumulation and cleavage. Collectively, our findings underscore the role of PARylation in controlling the pro-apoptotic function of HuR, offering insight into the mechanism by which PARP1/2 enzymes regulate cell fate and adaptation to various assaults.

Fusing Peptide Epitopes for Advanced Multiplex Serological Testing for SARS-CoV-2 Antibody Detection.

The tragic COVID-19 pandemic, which has seen a total of 655 million cases worldwide and a death toll of over 6.6 million seems finally tailing off. Even so, new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue to arise, the severity of which cannot be predicted in advance. This is concerning for the maintenance and stability of public health, since immune evasion and increased transmissibility may arise. Therefore, it is crucial to continue monitoring antibody responses to SARS-CoV-2 in the general population. As a complement to polymerase chain reaction tests, multiplex immunoassays are elegant tools that use individual protein or peptide antigens simultaneously to provide a high level of sensitivity and specificity. To further improve these aspects of SARS-CoV-2 antibody detection, as well as accuracy, we have developed an advanced serological peptide-based multiplex assay using antigen-fused peptide epitopes derived from both the spike and the nucleocapsid proteins. The significance of the epitopes selected for antibody detection has been verified by in silico molecular docking simulations between the peptide epitopes and reported SARS-CoV-2 antibodies. Peptides can be more easily and quickly modified and synthesized than full length proteins and can, therefore, be used in a more cost-effective manner. Three different fusion-epitope peptides (FEPs) were synthesized and tested by enzyme-linked immunosorbent assay (ELISA). A total of 145 blood serum samples were used, compromising 110 COVID-19 serum samples from COVID-19 patients and 35 negative control serum samples taken from COVID-19-free individuals before the outbreak. Interestingly, our data demonstrate that the sensitivity, specificity, and accuracy of the results for the FEP antigens are higher than for single peptide epitopes or mixtures of single peptide epitopes. Our FEP concept can be applied to different multiplex immunoassays testing not only for SARS-CoV-2 but also for various other pathogens. A significantly improved peptide-based serological assay may support the development of commercial point-of-care tests, such as lateral-flow-assays.

Evaluation of Potential Peptide-Based Inhibitors against SARS-CoV-2 and Variants of Concern.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has greatly affected all aspect of life. Although several vaccines and pharmaceuticals have been developed against SARS-CoV-2, the emergence of mutated variants has raised several concerns. The angiotensin-converting enzyme (ACE2) receptor cell entry mechanism of this virus has not changed despite the vast mutation in emerging variants. Inhibiting the spike protein by which the virus identifies the host ACE2 receptor is a promising therapeutic countermeasure to keep pace with rapidly emerging variants. Here, we synthesized two ACE2-derived peptides, P1 and P25, to target and potentially inhibit SARS-CoV-2 cell entry. These peptides were evaluated in vitro using pseudoviruses that contained the SARS-CoV-2 original spike protein, the Delta-mutated spike protein, or the Omicron spike protein. An in silico investigation was also done for these peptides to evaluate the interaction of the synthesized peptides and the SARS-CoV-2 variants. The P25 peptide showed a promising inhibition potency against the tested pseudoviruses and an even higher inhibition against the Omicron variant. The IC50 of the Omicron variant was 60.8 µM, while the IC50s of the SARS-CoV-2 original strain and the Delta variant were 455.2 µM and 546.4 µM, respectively. The in silico experiments also showed that the amino acid composition design and structure of P25 boosted the interaction with the spike protein. These findings suggest that ACE2-derived peptides, such as P25, have the potential to inhibit SARS-CoV-2 cell entry in vitro. However, further in vivo studies are needed to confirm their therapeutic efficacy against emerging variants.

Development and Testing of an Anatomic in vitro Kidney Model for Measuring Intrapelvic Pressure During Ureteroscopy.

OBJECTIVES: To create an in vitro anatomic bench model that can mimic in vivo intrapelvic pressure (IPP) during ureteroscopy (URS) and compare it against existing in vivo and ex vivo data. METHODS: A silicone kidney model (Simagine Health) that permits intrarenal endoscopic navigation was engineered to have a fluid-tight seal for the ureteral opening and a Tuohy-Borst valve in the renal pelvis incorporating a 0.2 mm pressure sensor (Opsens). To calibrate the model, a Cobra ureteroscope (Wolf) was inserted to the pelvis with 200cmH2O irrigation, and the valve adjusted until an IPP of 54cmH2O was obtained (prior human data). All experiments were conducted with a laser fiber in the working channel, with and without ureteral access sheaths (UAS) (11/13F, 13/15F) at irrigation setting of 61, 102, 153, and 193cmH2O using an automated system (Rocamed). Study outcome was mean steady-state IPP for each UAS/irrigation condition. RESULTS: Fluid leakage through the Tuohy-Borst valve, which could be adjusted, was critical to simulate ureteric outflow during URS. IPP values for each condition corresponded with data from in vivo and ex vivo models. In the no UAS condition, IPP increased with increasing irrigation pressures, and surpassed 40cmH2O when ≥153cmH2O. When using a UAS, IPP was below 40cmH2O for all irrigation pressures. CONCLUSIONS: An in vitro kidney model can simulate in vivo and ex vivo IPP profiles, and be tailored to different conditions by controlling fluid outflow. This bench model can be useful for testing of new technologies and their impact on IPP.

Strike Rate: Analysis of Laser Fiber to Stone Distance During Different Modes of Laser Lithotripsy.

Introduction: Different techniques of laser lithotripsy (fragmentation, dusting, and popcorning) are commonly used during ureteroscopy. The efficiency of a single laser pulse is dependent on minimizing laser fiber-stone distance, yet it has not been reported how often the laser fiber is in contact with the stone during laser lithotripsy. In this study, we sought to measure laser fiber to stone distance using light reflectance for each technique of laser lithotripsy. Methods: Continuous light from a 660 nm (red) light-emitting diode (LED) was coupled into a 200 µm fiber using a fiber X-coupler. The LED fiber was positioned immediately next to a 242 µm holmium fiber, and both were passed through the working channel of an ureteroscope. One fiber was used to deliver laser energy to the stone, and the other fiber was used to measure distance based on light reflected from the stone back into the fiber. For fragmentation and dusting experiments, a 5 mm BegoStone was placed into a 20 mm three-dimensional printed caliceal model. For popcorn experiments, 10 BegoStones (3 × 3 × 1.5 mm) were placed in an 11 mm caliceal model and the laser fiber positioned 2 mm away from the stone surface. Data were analyzed using a MATLAB software to report fiber to stone distance at each laser pulse. Results: With fragmentation, 52% of laser pulses were delivered when the fiber was within 0.5 mm of the stone compared to 23% and 4% for dusting and popcorning, respectively. Laser pulses delivered when fiber to stone distance was >1 mm (least effective) accounted for 34%, 48%, and >80% of total pulses during fragmentation, dusting, and popcorning, respectively. Conclusion: Current methods of laser lithotripsy that rely on fixed firing rates are inefficient, especially for the popcorn technique. These data highlight areas for improvement by appropriately gating pulse delivery to maximize lithotripsy effect for each pulse fired.

Fabrication of a Lateral Flow Assay for Rapid In-Field Detection of COVID-19 Antibodies Using Additive Manufacturing Printing Technologies.

The development of lateral flow immunoassay (LFIA) using three-dimensional (3D) printing and bioprinting technologies can enhance and accelerate the optimization process of the fabrication. Therefore, the main goal of this study is to investigate methods to speed up the developing process of a LFIA as a tool for community screening. To achieve this goal, an in-house developed robotic arm and microfluidic pumps were used to print the proteins during the development of the test. 3D printing technologies were used to design and print the housing unit for the testing strip. The proposed design was made by taking into consideration the environmental impact of this disposable medical device.

In Vivo Evaluation of a Novel Pigtail Suture Stent.

OBJECTIVE: To compare pressure, dilation, and histology in a porcine model after stenting with a pigtail suture stent (PSS)-where the ureteral and bladder component consists of a suture and a double J (DJ) stent. METHODS: Twelve pigs were studied with a PSS (4.8F/MiniJFil®) and DJ stent (4.8F/RocaJJ Soft) inserted in both sides, except in one where the DJ was not placed to serve as control. Intrapelvic pressure (IPP) and ureteral pressures were recorded. Five pigs were stented for 7 days, and the next 7 for 13-15 days, where a retrograde study was performed after stent removal. Ureteral histology in 4 and 3 pigs stented for 7- and 13-15 days, respectively, were assessed in a blinded manner. RESULTS: In total, 11 renal units were stented with PSS and DJ, respectively. There was a rise in IPP and ureteral pressure after stenting. There were no significant differences in post-stenting pressures between DJ and PSS systems. Ureteral dilation occurred in 100% of DJ and 83% of PSS units. PSS suture migration occurred in 3 of 11. Gross edema at the ureteral orifice was greater with the DJ compared to the PSS (82% vs 18%; p = .003). Histology demonstrated greater inflammation at the ureteral orifice in the DJ group (2.3 vs 1; p = .016) when stented for 13-15 days. CONCLUSION: There was no difference in IPP after stenting with a PSS compared to a DJ stent. When stented for 13-15 days, the PSS resulted in ureteral dilation, but with less edema and inflammation at the ureteral orifice.

Patterns of Laser Activation During Ureteroscopic Lithotripsy: Effects on Caliceal Fluid Temperature and Thermal Dose.

Introduction: Characterizing patterns of laser activation is important for assessing thermal dose during laser lithotripsy. The objective of this study was twofold: first, to quantify the range of operator duty cycle (ODC) and pedal activation time during clinical laser lithotripsy procedures, and second, to determine thermal dose in an in vitro caliceal model when 1200 J of energy was applied with different patterns of 50% ODC for 60 seconds. Methods: Data from laser logs of ureteroscopy cases performed over a 3-month period were used to calculate ODC (lasing time/lithotripsy time). Temporal and rolling 1-minute average power tracings were generated for each case. In vitro experiments were conducted using a 21 mm diameter glass bulb in a 37°C water bath, simulating a renal calix. A LithoVue ureteroscope with attached thermocouple was inserted and 8 mL/min irrigation was delivered with a 242 µm laser fiber within the working channel. In total, 1200 J of laser energy was applied in five different patterns at 20 W average power for 60 seconds. Thermal dose was calculated using the Sapareto and Dewey t43 method. Results: A total of 63 clinical cases were included in the analysis. Mean ODC was 32% overall and 63% during the 1-minute of greatest energy delivery. Mean time of pedal activation was 3.6 seconds. In vitro studies revealed longer pedal activation times produced higher peak temperature and thermal dose. Thermal injury threshold was reached in 9 seconds when 40 W was applied at 50% ODC with laser activation patterns of 30 seconds on/off and 15 seconds on/off. Conclusion: ODC was quantified from clinical laser lithotripsy cases: 32% overall and 63% during 1-minute of peak power. Time of pedal activation is an important factor contributing to fluid heating and thermal dose. Awareness of these concepts is necessary to reduce risk of thermal injury during laser lithotripsy procedures.

Assessing the Role of Light Absorption in Laser Lithotripsy by Isotopic Substitution of Kidney Stone Materials.

Understanding the chemical characteristics of kidney stones and how the stone composition affects their fragmentation is key to improving clinical laser lithotripsy. During laser lithotripsy, two mechanisms may be responsible for stone fragmentation: a photothermal mechanism and/or microexplosion mechanism. Herein, we carry out an isotopic substitution of crystal H2O with D2O in calcium oxalate monohydrate and struvite stones to alter their optical properties to study the relationship between the absorption of the stones, at the wavelength of the Ho:YAG (2.12 µm) laser, and the fragmentation behavior. Changing the absorption of the stones at 2.12 µm changes the extent of fragmentation, whereas changing the absorption of the bulk medium has a negligible effect on fragmentation, leading to the conclusion that kidney stone ablation is dominated by a photothermal mechanism.

Defining Thermally Safe Laser Lithotripsy Power and Irrigation Parameters: In Vitro Model.

Introduction: High-power laser settings are commonly employed for stone dusting techniques. Previous in vitro and in vivo studies have demonstrated that a toxic thermal dose can result from treatment within a renal calix without adequate irrigation. Hence, both laser power and irrigation rate must be considered together to determine safe laser lithotripsy parameters. The objective of this in vitro study was to map parameter safety boundaries and create guidelines for selection of safe laser and irrigation settings. Methods: The experimental system consisted of in vitro models simulating ureter, renal calix, and renal pelvis placed in a water bath maintained at 37°C. Temperature was recorded during ureteroscopy with laser activation for 60 seconds. Trials were conducted at strategically selected power levels and irrigation rates. Thermal dose for each trial was calculated based on Sapareto and Dewey t43 methodology with thermal dose >120 equivalent minutes considered to result in thermal tissue injury. A parameter safety boundary was established by plotting the maximal safe power level for each irrigation rate. Results: The parameter safety boundary was found to be linear for each scenario with the renal pelvis able to tolerate the highest laser power and the renal calix the least power without injury. Conclusion: This study describes the methodology to determine parameter safety boundaries that can be used to guide proper selection of thermally safe laser settings and irrigation rates during ureteroscopy with laser lithotripsy. This work provides a framework to assess the effectiveness of various strategies to control and mitigate thermal dose.

Frequency Threshold for Ablation During Holmium Laser Lithotripsy: How High Can You Go?

Purpose: We performed in vitro studies to assess the relationship of pulse frequency on stone ablation during contact laser lithotripsy and determine if there is a threshold after which its effect on lithotripsy is limited. Methods: BegoStones were fragmented using a Ho:YAG laser (P120 Moses) and a 230 µm fiber at 0.5 J on long pulse (LP) and Moses distance (MD) modes in contact with the stone. The relationship between the number of pulses (1-40 Hz) on stone crater volume was assessed using three-dimensional confocal microscopy and nonlinear-segmented regression. To simulate a painting technique, we assessed fragmentation (mg/second) at 20, 40, and 60 Hz, with the fiber moving at a speed of 1 and 3 mm/second, respectively. High-speed imaging was used to record ablation. Results: When the laser fiber was fixed, after 13.0 (LP) and 15.4 (MD) pulses, greater pulse frequency did not lead to a significant increase in stone crater volume. Fragmentation was greatest at higher frequencies and faster fiber speed. Increasing the frequency from 20 to 60 Hz at 3 mm/second increased fragmentation by 82% and 61% for LP and MD modes, respectively. Using high-speed data, if the laser fiber is moving at 1 mm/second, a hypothetical frequency threshold for ablation was calculated to be 52 and 61.6 Hz for LP and MD modes, respectively. Conclusion: Increasing the fiber speed increases stone ablation when using high frequency settings. When the fiber is fixed there is a threshold after which increasing the pulse frequency leads to minimal gain in ablation. The exact value for threshold when the fiber is moving needs further study. Our study serves to provide insight for parameter selection and safety of laser lithotripsy for dusting technique.

Emerging Laser Techniques for the Management of Stones.

Next-generation holmium laser systems provide the user with a range of parameters that can help optimize fragmentation efficiency. Ureteroscopic strategies broadly consist of fragmentation with active retrieval, or dusting, which uses low pulse energy settings to break stones into fine fragments for spontaneous passage. Techniques for dusting include dancing, chipping, and popcorning. The Moses technology is a multipulse mode that may help reduce retropulsion and increase fragmentation. The thulium fiber laser is an emerging laser technology that provides an extensive parameter range for dusting. Future studies are needed to define the role of these technologies and techniques for laser lithotripsy.

Watch Your Distance: The Role of Laser Fiber Working Distance on Fragmentation When Altering Pulse Width or Modulation.

INTRODUCTION: The Moses technology for the Ho:YAG laser introduces a pulse-shape modulation that optimizes energy delivery through water and can be utilized for lithotripsy at a distance from the target. In light of this advance, we undertook an in vitro study to assess the effect of fiber tip to stone distance on fragmentation, incorporating the use of a variety of pulse modes. METHODS: Experiments were conducted with a three-dimensional (3D) positioning system, a 30 mm flat plate BegoStone, and a 230 µm core laser fiber connected to a 120W holmium laser utilizing short pulse (SP), long pulse (LP), Moses contact (MC), and Moses distance (MD) modes. Ablation crater volume was measured by 3D confocal microscopy, after a single pulse (1.0 J) was activated with the fiber tip positioned at 0, 0.5, 1, 2, and 3 mm from the stone. Fragmentation efficiency (1 J × 10 Hz) was assessed with the fiber tip at 0 and 1 mm distance, programmed to fragment the stone over 3 minutes. Fragmentation was defined as difference in stone mass before and after each experiment. RESULTS: For all tested pulse modes, ablation crater volume and fragmentation were greatest when the fiber tip was in contact with the stone. Ablation declined as the working distance increased with no ablation occurring at 3 mm. At 1 mm distance, the ablation crater volume using MD mode was significantly higher when compared with SP, LP, and MC modes (p < 0.05). Compared with all pulse modes tested, MD resulted in 28% and 39% greater fragmentation at both 0 and 1 mm working distances, respectively (p < 0.05). CONCLUSION: Holmium laser lithotripsy is significantly affected by fiber working distance with the greatest ablation obtained with the fiber in contact with the stone. At 0 and 1 mm distance, MD had the greatest fragmentation efficiency, suggesting this mode may have advantages during ureteroscopy.

Ambulatory Tubeless Mini-Percutaneous Nephrolithotomy Using Moses Technology and Dusting Technique.

OBJECTIVE: To demonstrate the use of the Moses technology for holmium laser lithotripsy in conjunction with mini-percutaneous nephrolithotomy (PCNL) to treat a lower pole stone. The Moses technology is a pulse modulation method that can reduce stone retropulsion, which may have advantages when used during mini-PCNL. METHODS: A 63-year-old patient with a right-sided 1.5 cm lower pole stone (1300 Hounsfield Unit) underwent mini-PCNL using a 120W holmium laser (MosesP120, Lumenis). Moses has 2 modes-"Contact" and "Distance"-optimized for operation at 0-1 and 2-3 mm from the stone surface, respectively. Percutaneous access was obtained into the lower pole while the patient was in prone position. Using the medium (17.5F) mini-PCNL set (Karl Storz), the stone was fragmented using dusting settings with a 230 µm Moses fiber (0.3 J × 20-30 Hz; Moses Contact and Distance modes). RESULTS: The video demonstrates the capabilities of treating a lower pole stone with a dusting technique using Moses modes. Dusting, to decrease the stone size so that it can fit within the sheath, in combination with fragment expulsion with the Venturi effect, as well as extraction with graspers/baskets resulted in complete stone removal. Following placement of an antegrade ureteral stent (tubeless technique) and sealing of the tract with FloSeal, the patient was discharged from the recovery unit. There were no adverse events. The stent was removed after 7 days, and follow-up KUB at 2 weeks showed no residual fragment. CONCLUSION: Due to the miniaturization of equipment, the holmium laser serves as an ideal energy source for fragmentation. In our early experience, the Moses technology with mini-PCNL allows a combination of dusting and stone extraction. As mini-PCNL offers smaller tract dilatation, for lower pole stones it can be performed in an ambulatory setting and is an alternative to ureteroscopy or shockwave lithotripsy with the potential for complete stone clearance.

Simulation of Laser Lithotripsy-Induced Heating in the Urinary Tract.

PURPOSE: Holmium laser lithotripsy is a common modality used to fragment urinary stones during ureteroscopy. Laser energy deposited during activation produces heat and potentially causes thermal bioeffects. We aimed to characterize laser-induced heating through a computational simulation. MATERIALS AND METHODS: A finite-element model was developed and used to estimate temperature in the urinary tract. Axisymmetric models of laser lithotripsy in a renal calyx, the renal pelvis, and proximal ureter were created. Heat generation by laser and heat transfer were simulated under different laser powers between 5 and 40 W. Irrigation fluid flow was introduced at rates between 0 and 40 mL/min. The model was validated by comparison with previous in vitro temperature data in a test tube, then used to calculate heating and thermal dose in the three tissue models. RESULTS: Simulated temperature rises agreed well with most in vitro experimental measurements. In tissue models, temperature rises depended strongly on laser power and irrigation rate, and to a lesser extent on location. Injurious temperatures were reached for 5-40 W laser power without irrigation, >10 W with 5 mL/min irrigation, 40 W with 15 mL/min irrigation, and were not found at 40 mL/min irrigation. Tissue injury volumes up to 2.3 cm3 were calculated from thermal dose. CONCLUSIONS: The results suggest a numerical model can accurately simulate the thermal profile of laser lithotripsy. Laser heating is strongly dependent on parameters and may cause a substantial temperature rise in the fluid in the urinary tract and surrounding tissue under clinically relevant conditions.

Are We Cutting Ourselves Short? Laser Lithotripsy Performance Based on Differences in Fiber-tip Preparation.

OBJECTIVE: To better understand the impact of laser fiber-tip configuration on lithotripsy performance, we undertook an in vitro study comparing 3 fiber-tip configurations: (1) new (single-use), (2) cleaved (reusable), and (3) coated (cut with scissors). METHODS: Lithotripsy was performed using a Ho:YAG laser utilizing fragmentation (1 J × 10 Hz) and dusting (0.5 J × 20 Hz) settings. BegoStones were fragmented with a laser fiber advancing at a speed of 1 mm/s (220 seconds of activation). Three fiber-tip configurations were tested: new single-use standard (242 µm core) and cleaved (272 µm core), compared to the same fiber-tip coated/cut flush with scissors, respectively. Study outcome was difference in stone mass before and after each experiment. Power output was measured using a power meter. RESULTS: Fragmentation for new or cleaved fibers was greater than the coated/cut flush fiber-tip (P <.05). For 1 J × 10 Hz and 0.5 J × 20 Hz settings, fragmentation was 59% and 75% higher with new fiber-tip compared to the coated/cut flush fiber-tip, respectively. For 1J × 10 Hz and 0.5 J × 20 Hz settings, fragmentation was 51% and 45% higher with cleaved fiber-tip compared to the coated/cut flush fiber-tip, respectively. Power output at the end of laser activation was higher for new and cleaved fiber-tips. CONCLUSION: New and cleaved laser fibers demonstrated superior lithotripsy performance compared to fibers that were coated/cut flush with scissors. Cutting single-use laser fibers risks damaging the fiber-tip which can disperse the energy and reduce lithotripsy efficiency.

Polymer-Mineral Composites Mimic Human Kidney Stones in Laser Lithotripsy Experiments.

Despite the widespread use of laser lithotripsy to fragment kidney stones in vivo, there is a lack of robust artificial stone models to replicate the behavior of human stones during lithotripsy procedures. This need for accurate stone models is particularly important as novel laser technologies are introduced in the field of lithotripsy. In this work, we present a method to prepare composite materials that replicate the properties of human kidney stones during laser lithotripsy. Their behavior is understood through the lens of near-IR spectroscopy and helps to elucidate the mechanism of laser lithotripsy in kidney stone materials.