Comparative proteomic profiling of uric acid, ammonium acid urate, and calcium-based kidney stones.

INTRODUCTION: Kidney stone matrix proteins may help explain cellular mechanisms of stone genesis. However, most existing proteomic studies have focused on calcium oxalate stones. Here, we present a comparative proteomic analysis of different kidney stone types. METHODS: Proteins were extracted from the stones of patients undergoing percutaneous nephrolithotomy (PCNL). Approximately 20 µg of protein was digested into tryptic peptides using filter aided sample preparation, followed by liquid chromatography tandem-mass-spectrometry using an EASY-nLC 1200 and Orbitrap Fusion Lumos mass spectrometer. A standard false discovery rate cutoff of 1% was used for protein identification. Stone analysis was used to organize stone samples into similar groups. We selected the top 5% of proteins based on total ion intensities and used DAVID and Ingenuity Pathway Analysis to identify and compare significantly enriched gene ontologies and pathways between groups. RESULTS: Six specimens were included and organized into the following four groups: 1) mixed uric acid (UA) and calcium-based, 2) pure UA, 3) pure ammonium acid urate (AAU), and 4) pure calcium-based. We identified 2,426 unique proteins (1,310-1,699 per sample), with 11-16 significantly enriched KEGG pathways identified per group and compared via heatmap. Based on number of unique proteins identified, this is the deepest proteomic study of kidney stones to date and the first such study of an AAU stone. CONCLUSIONS: The results indicate that mixed UA and calcium-based kidney stones are more similar to pure UA stones than pure calcium-based stones. AAU stones appear more similar to pure calcium-based stones than UA containing stones and may be related to parasitic infections. Further research with larger cohorts and histopathologic correlation is warranted.

Reverse Trendelenburg Positioning Minimizes Stone Retropulsion During Ureteroscopic Laser Lithotripsy: A Prospective Randomized Study.

Purpose: Retropulsion of stone fragments during ureteroscopic laser lithotripsy (URSLL) remains a challenge for urologists and is associated with increased operative time and reduced stone-free rate (SFR). In this study, we compared the rate of retropulsion of ureteral stones during URSLL between the standard dorsal lithotomy (SDL) position and dorsal lithotomy position with reverse Trendelenburg (RT). Materials and Methods: Patients with ureteral stones requiring surgical intervention between May 2019 and January 2022 were randomized to undergo URSLL in either SDL or RT positions. The primary outcome of this study was stone retropulsion. Secondary outcomes included retropulsion to the kidney, SFR, operative time, 30-day emergency department visits and complications, and the need for conversion from semirigid to flexible ureteroscope. Differences between groups were evaluated using the chi-square test, Fisher exact test, Kruskal-Wallis test, or t-test. Results: A total of 114 patients were included in the study, with 57 patients in each group. There were no differences between groups in terms of baseline demographics or stone characteristics. Retropulsion was significantly less frequent in the RT group (68.4% vs 10.5%, p < 0.01). Similarly, the RT group was favored for lower risk of retropulsion into the kidney (40.4% vs 5.3%, p < 0.01), operative time (43.5 vs 33.0 minutes, p = 0.02), and need for ureteroscope conversion (16.7% vs 2.2%, p = 0.04). There was no difference in the SFR (100% vs 95%, p = 0.49). Conclusions: RT positioning during URSLL for ureteral stones significantly decreases the rate of stone retropulsion, operative time, and the need for conversion from semirigid to flexible ureteroscope.

Criteria Used by Endourology Society Fellowship Program Directors for the Selection and Evaluation of Fellows.

Introduction: An understanding of which trainee factors Endourology Society (ES) fellowship program directors (PDs) value may help urology residents optimize their fellowship candidacy and help current fellows optimize their fellowship performance. In the present study, we evaluated which factors are most important to ES PDs in selecting fellowship candidates and evaluating current fellows. Materials and Methods: A survey was constructed using Research Electronic Data Capture (REDCap) software and emailed to PDs of fellowships registered with the ES. Fellowships in the ES include Endourology/kidney stone disease (ESD) programs, robotic-laparoscopic surgery programs (MIS), and combination programs. A Likert scale ranging from 1 (not important) to 5 (extremely important) was used to rank the criteria for selecting and evaluating fellows. The survey captured program demographics such as geographic region, program type, and program duration. Results: Of the 52 ES PDs, 35 (67%) responded. Respondents represented 8 (23%) ESD programs, 7 (20%) MIS programs, and 20 (57%) combination programs. Furthermore, 16 (46%) represented 1-year programs and 19 (54%) represented 2-year programs. The top-five factors for candidate selection were perceived fit of the applicant, perceived level of applicant interest, initial interview, personal emails from applicants' advocates, and personal phone calls from applicants' advocates. Advocacy on behalf of the applicant appeared to be especially important for 2-year fellowships. The top-five factors for the evaluation of fellows in training were patient interactions, professionalism, attitude/demeanor, operative skills, and interactions with ancillary staff. Research productivity was of greater importance for the evaluation and selection of 2-year fellows and ESD fellows. Conclusions: Applicants for ES fellowships should focus on the initial interview and recruiting supportive mentors to advocate for their applications, particularly for 2-year programs. Although PDs value both clinical skills and research productivity, research productivity was more important for 2-year programs and ESD programs. Further research into applicant perspectives on the fellowship application process is warranted.

Do Infection-Associated Stone Subtypes Behave the Same Clinically? A Retrospective Bicenter Study.

Introduction and Objectives: Infection-associated renal stones are commonly composed of magnesium-ammonium-phosphate (MAP) and carbonate apatite (CA). The clinical implications of these two different, but closely related stone types, are unknown. We sought to compare the clinical, microbiologic, and metabolic characteristics of patients with MAP and CA stone types. Methods: We retrospectively reviewed the medical records of patients from two centers (one in the United States and one in Israel) who underwent ureteroscopy or percutaneous nephrolithotomy between 2012 and 2020 and identified patients with a predominant stone analysis component of CA or MAP and clinical data supporting an infection stone. We analyzed and compared demographic data, medical history, postoperative fever, stone and urinary microbiology, and 24-hour urine studies. Results: A total of 79 and 75 patients met the inclusion criteria for the MAP and CA cohorts, respectively. No significant difference was found in patient demographics or comorbidities between the MAP and CA cohort. Female predominance was noted in both. Although there were no significant differences in 24-hour urine parameters between the cohorts, hypercalciuria was common in both cohorts (38% and 32% of patients in the MAP and CA cohorts, respectively). Gram-negative bacteria were more common in the MAP stone cultures. Postoperative fever was significantly more common in the MAP cohort (14.7% vs 3.8%, p < 0.016). Conclusions: MAP and CA stone formers share similar demographic characteristics with a clear female predominance. MAP stones patients appear more likely to develop postoperative fever, possibly related to a higher occurrence of gram-negative bacteria in the stone cultures of the MAP cohort. Although there were no significant differences among metabolic parameters, hypercalciuria was noted in approximately a third of the cohort. The clinical significance of this finding is yet to be determined.

The Surgical Technique of Mini Percutaneous Nephrolithotomy.

The mini percutaneous nephrolithotomy (mini-PCNL) has become a versatile tool to remove kidney stones >2 cm, lower pole stones >1 cm, renal stones previously unresponsive to shockwave therapy or inaccessible by ureteroscopy (within a caliceal diverticulum), stones within complex urinary tracts (urinary diversions, transplanted kidney, and horseshoe kidneys), and large impacted proximal ureteral stones. After positioning in either the supine or prone position, a cystoscopy is performed to place an open-ended catheter, occlusion balloon, or Accordian device into the collecting system. A foley catheter is placed in the bladder. An ultrasound with a curvilinear probe is used to survey the kidney and guide access into the collecting system with an 18 g percutaneous needle. Once access is obtained, a small 0.5 cm skin incision is made and the percutaneous tract is dilated over a wire. A 16.5F metallic or self-dilating suctioning access sheath is positioned with fluoroscopic guidance. A 12F rigid mini-PCNL nephroscope is used to evaluate the collecting system. Once a calculus is observed, options for stone fragmentation include a lithotripter with ultrasonic and ballistic energy, or laser lithotripsy using holmium or thulium laser fibers. Flexible ureteroscopy can be considered to ensure clearance of the collecting system. A 6F ureteral stent can be placed in either a retrograde or antegrade approach for drainage. The tract is sealed using Surgiflo hemostatic matrix with thrombin. Guidelines for postoperative care and troubleshooting techniques for mini-PCNL are reviewed along with the surgical steps in the accompanying video (Supplementary Video S1). There are few randomized trials comparing mini-PCNL with standard PCNL and ureteroscopy. There is some evidence to suggest a difference in transfusion rates comparing mini- and standard PCNL, as well as differences in stone-free rates when comparing mini-PCNL with ureteroscopy for the treatment of lower pole stones.

Prevention and Management of Infectious Complications of Retrograde Intrarenal Surgery.

Kidney stone disease (KSD) is a commonly encountered ailment in urologic practice. Urinary tract infection (UTI) is commonly associated with KSD, both as an etiology (e.g., struvite and carbonate apatite stones), and as a complication (i.e., obstructive pyelonephritis and post-operative UTI). Indeed, a significant portion of the economic burden of KSD is skewed toward stones associated with infection. UTI is the most common post-operative complication related to stone intervention with progression to urosepsis as a rare but serious consequence. Risk for infection is influenced by a variety of factors including co-morbid conditions, anatomic abnormalities, prior surgical procedures, and local anti-microbial susceptibility. Understanding these risks and the proper steps to mitigate them is an essential component in reducing post-operative morbidity and mortality. Retrograde intrarenal surgery is routinely used for the treatment of KSD. The objective of this review article is to examine the current literature and guidelines for the prevention and management of stone-related infectious complications associated with retrograde intrarenal surgery. Special attention will be given to the incidence, etiology, and antibiotic prophylaxis choice in the management of stone-related infections. Intraoperative risk mitigation techniques will be discussed in conjunction with the management of post-operative infections. Antibiotic stewardship and the potential benefits of reduced empiric antibiotic treatment will also be discussed.

Thulium fiber laser utilization in urological surgery: A narrative review.

The thulium fiber laser (TFL) is a novel technology under active investigation as an conceivable alternative to the Holmium:yttrium-aluminum-garnet (Ho:YAG) laser, which is currently the gold standard for an array of urologic procedures. The purpose of this review is to discuss the existing literature on the functionality and effectiveness of TFL in urological practice. We conducted a search of the PubMed, Medline, Web of Science Core Collection, SCOPUS, Embase (OVID), and Cochrane Databases for all full articles and systematic reviews on the TFL. We found a total of 35 relevant pieces of literature. The early research findings pertaining to the TFL exhibit numerous potential advantages over the Ho:YAG laser. In vitro and ex vivo studies have highlighted the TFL's ability to utilize smaller laser fibers, obtain faster stone ablation rates, and achieve less retropulsion when tested against the Ho:YAG laser in lithotripsy. Currently, there is limited in vivo research that investigates the utilization of the TFL. The in vivo results that are available, however, look promising both for laser lithotripsy and soft tissue ablation. Indeed, the existing literature suggests that the TFL has great potential and may possess numerous technological advantages over the Ho:YAG laser, especially in laser lithotripsy. Although these early studies are promising, randomized control trials are needed to assess the full applicability of the TFL in urology.

Cancer, Mortality, and Acute Kidney Injury among Hospitalized Patients with SARS-CoV-2 Infection.

BACKGROUND: To evaluate Coronavirus Disease 2019-(COVID19) patients treated within our academic medical system to determine if history of malignancy, both in general and specifically in genitourinary oncology patients, is associated with adverse clinical outcomes, including acute kidney injury (AKI) and mortality. METHODS: We conducted a retrospective cohort study among patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in a multi-hospital, academic medical institution in New York City. Outcomes included mortality, intensive care unit (ICU) admission and AKI among hospitalized patients. We also evaluated risk of hospitalization among all patients with SARS-CoV-2 infection. Multilevel logistic regression models were used for analysis. RESULTS: We identified 6,893 patients who met inclusion criteria, of which 4,018 were hospitalized. Among hospitalized patients 374 (9%) had a history of cancer, 281 (7%) experienced AKI, and 1,045 (26%) died. In adjusted analyses, patients with a history of cancer had 1.33 (95% CI = 1.05, 1.69) times the odds of death compared to those without cancer and this appeared to be driven by lung cancer (odds ratio (OR) = 2.44, 95% CI= 1.05, 4.39). Patients with a history of genitourinary cancer were not at higher risk of mortality compared to those without cancer (OR=0.99, 95% CI= 0.61, 1.62). History of cancer was not associated with ICU admission or AKI in overall and subgroup analyses. CONCLUSIONS: Patients with a history of cancer who are hospitalized with SARS-CoV-2 infection are not at greater risk for AKI, though they are at higher risk for mortality as compared to patients without a history of cancer. The increased risk in mortality appears driven by patients with pulmonary neoplasms. Patients with a history of genitourinary malignancies do not appear to be at higher risk for AKI or for mortality compared to the general population.

Changing the Status Quo: The 100 Most-Disruptive Papers in Urology?

OBJECTIVE: To identify key papers in urology using a novel bibliometric index called the disruption score. METHODS: A PubMed search was conducted to identify papers published in Journal of Urology, European Urology, Urology, Urologic Oncology, Journal of Endourology, and BJU International, Nature Reviews Urology. Selected urology papers published in other medical journals were also included. Using a validated dataset of disruption scores for all papers published in 1954-2014, the top 100 most-disruptive urology papers, as well as the top 100 most-cited papers, were identified. Comparisons between both lists and across journals were investigated. RESULTS: A total of 72,623 published articles were included. Journal of Urology had the most articles in the most-disruptive papers list (n = 69) followed by BJU International (n = 16). New England Journal of Medicine had the most papers in the most-cited papers list (n = 26) followed by Journal of Urology (n = 23). Only 7 papers were common to both the most-disruptive papers and most-cited papers lists. Oncology was highly represented among the most-cited papers (n = 60), whereas the most-disruptive papers included a broader representation of urology. The most common study design among the most disruptive papers was small case-series/case reports, whereas the most common study design among the most-cited papers was randomized controlled trials. CONCLUSION: The disruption score identified landmark papers in urology that have introduced innovative ideas. Disruption score captures a unique profile of scientific impact that may be used in combination with other bibliometric indices to identify scholarly achievements in urology.

Management of a Massive Bladder Stone Burden in an Elderly Comorbid Woman via a Transurethral Approach.

Here we present the case of a 78-year-old medically comorbid woman with an extremely large bladder stone burden treated by cystolithalopaxy performed using a Swiss LithoClast® Trilogy Lithotripter (Boston Scientific, Marlborough, MA, USA) through a nephroscope traversing a transurethral Amplatz sheath.