Mechanistic Studies of a Skatole-Forming Glycyl Radical Enzyme Suggest Reaction Initiation via Hydrogen Atom Transfer.

Gut microbial decarboxylation of amino acid-derived arylacetates is a chemically challenging enzymatic transformation which generates small molecules that impact host physiology. The glycyl radical enzyme (GRE) indoleacetate decarboxylase from Olsenella uli (Ou IAD) performs the non-oxidative radical decarboxylation of indole-3-acetate (I3A) to yield skatole, a disease-associated metabolite produced in the guts of swine and ruminants. Despite the importance of IAD, our understanding of its mechanism is limited. Here, we characterize the mechanism of Ou IAD, evaluating previously proposed hypotheses of: (1) a Kolbe-type decarboxylation reaction involving an initial 1-e- oxidation of the carboxylate of I3A or (2) a hydrogen atom abstraction from the α-carbon of I3A to generate an initial carbon-centered radical. Site-directed mutagenesis, kinetic isotope effect experiments, analysis of reactions performed in D2O, and computational modeling are consistent with a mechanism involving initial hydrogen atom transfer. This finding expands the types of radical mechanisms employed by GRE decarboxylases and non-oxidative decarboxylases, more broadly. Elucidating the mechanism of IAD decarboxylation enhances our understanding of radical enzymes and may inform downstream efforts to modulate this disease-associated metabolism.

Testicular schistosomiasis: a systematic review of the literature.

INTRODUCTION: To consolidate reported information on presentation, diagnosis, and treatment modalities in testicular schistosomiasis (TS) to provide a reference tool for this rare disease. MATERIALS AND METHODS: A comprehensive PubMed search was performed using PRISMA guidelines, which yielded 21 articles detailing 22 cases of TS. RESULTS: Testicular schistosomiasis remains a rare disease, presenting at a variety of ages (median age 27). All reports of this condition are associated with exposure to an endemic area. The most common presenting symptoms include nonspecific testicular swelling (54.5%) followed by a testicular mass/nodule (18.4%). Diagnosis relies upon clinical suspicion due to low specificity on laboratory and imaging evaluation, with only 18% of urine evaluations positive for parasitic infection. Final diagnosis was made on biopsy (38.1%), radical orchiectomy (47.6%) or frozen section during partial orchiectomy (14.3%). Treatment included anthelmintic mediation (37%), radical/partial orchiectomy (31%), or some combination of the above. CONCLUSIONS: This systematic review of individual patient data reveals that while urine tests and imaging may aid in diagnosis, all patients require definitive histologic diagnosis. It is important to obtain a thorough history to elucidate exposure to endemic areas and inform whether biopsy, and subsequent testicular preservation, may be appropriate.

Mechanical failure rates of artificial urinary sphincter components: Is the 3.5-cm urethral cuff at higher risk?

AIM: We report the rates of artificial urinary sphincter (AUS) mechanical failure in a contemporary cohort of patients stratified by component type and size to determine if the 3.5-cm cuff is at higher risk of failure. METHODS: From 2005-2016, a total of 486 male patients with stress incontinence underwent implantation or revision of an AUS. 993 individual cases were retrospectively reviewed (465 primary placements and 528 revisions). Components were separately tallied and cases of mechanical failure were identified. Multiple variables including duration until failure and follow-up interval were collected and analyzed for each malfunction. RESULTS: After median follow-up of 31.5 months, there were 48 distinct cases of mechanical failure. The urethral cuff was the most common component to fail (n = 27, 56.3%), followed by the pressure regulating balloon (PRB) (n = 6, 12.5%), tubing (n = 6, 12.5%), and the control pump, (n = 5, 10.4%). Four (8.3%) cases did not have the source of malfunction identifiable in available records though fluid loss was evident at the time of device interrogation. Sub-analyses of cuff failure events showed that the 3.5-cm cuff had a statistically significant higher risk of failure (HR: 7.313, (P < .0001) compared to larger cuff sizes. CONCLUSIONS: While each component is prone to malfunction, our study suggests that the 3.5-cm urethral cuff is more susceptible to failure and failure events occur earlier after placement than larger cuff sizes.

Importance of Nitrogen-Hydrogen Bond pKa in the Catalytic Coupling of Alkenes and Amines by Amidate Tantalum Complexes: A Computational Study.

Density functional theory (DFT) was carried out to study the impact of substituents with different electronic properties upon hydrogen transfer as the rate-determining step in the hydroaminoalkylation catalytic cycle in order to determine the character of the hydrogen atom in the transition state. In the transition state of the rate-determining step, an N-methylaniline substrate ligates to Ta and transfers its hydrogen to the α-carbon of a five-membered tantallacycle and a Ta-C bond is thus broken. Study of the activation energy barriers resulting from the different para- and meta-substituted N-methylanilines and their correlation with computed pKa and bond dissociation free energy (BDFE) values of the N-methylanilines show more obvious correlations between pKa and ΔG‡ values. Assessing the asynchronicity parameter (η) for the studied substituents reveals that pKa is a larger driving force in the rate-determining hydrogen transfer reaction than the BDFE, which suggest a reasonable amount of protic character in the transition state, and possible routes to the design of more active catalysts with greater substrate scope.

Clinical Presentations of Melanoma in African Americans, Hispanics, and Asians.

BACKGROUND: Skin cancer has traditionally been studied in Caucasian skin. Although it does occur with increased relative frequency in Caucasians, patients with skin of color suffer from elevated morbidity and mortality when diagnosed with skin cancer. OBJECTIVE: To detail the unique demographic, clinical, and genetic features of melanoma in patients with skin of color, including Hispanic, African American, and Asian patients. MATERIALS AND METHODS: A PubMed search was conducted spanning dates 1947 to June 2017. A total of 246 articles were screened, from which 69 were included in this review. RESULTS: Relative to Caucasians, melanoma has unique demographic, clinical, and genetic features in African Americans, Hispanics, and Asians that include gender and subtype predominance. CONCLUSION: Familiarization with these unique presentations of skin cancer in skin of color is imperative to accurate identification and treatment of cutaneous malignancies in these populations and ultimately to improved disease-related outcomes.

Review of Endovenous Thermal Ablation of the Great Saphenous Vein: Endovenous Laser Therapy Versus Radiofrequency Ablation.

BACKGROUND: Endovenous thermal ablation is a popular treatment for varicose veins of the greater saphenous vein. Two common techniques of thermal ablation are endovenous laser therapy (EVLT) and radiofrequency ablation (RFA). OBJECTIVE: The authors compare EVLT and RFA in vein therapy. METHODS: A review was conducted using PubMed. Studies comparing the treatment modalities were gathered and compared on the basis of 5 main standpoints, including: efficacy, side effects, serious complications, recurrence, and quality of life. RESULTS: It was found that EVLT and RFA are both highly efficacious (>80%). Endovenous laser therapy seems to be slightly more efficacious than RFA in numerous studies but its significance is uncertain. Side effect profiles varied regarding postoperative pain and bruising because both were seen to be significantly less using RFA. Serious complications were found to be rare in both with no significant difference in incidence. Recanalization rate was observed to be higher using RFA with uncertainty in significance among various studies. Quality of life improved after both procedures with no significant difference among the 2. CONCLUSION: Efficacy and recurrence rate seem to favor EVLT, whereas postoperative pain and bruising favor RFA. Further studies are needed to validate the significance of the differences found.

Review of Nonmelanoma Skin Cancer in African Americans, Hispanics, and Asians.

BACKGROUND: Skin cancer has traditionally been studied in Caucasian skin. Although it does occur with increased relative frequency in Caucasians, patients with skin of color suffer from elevated morbidity and mortality when diagnosed with skin cancer. OBJECTIVE: To detail the unique demographic and clinical features of nonmelanoma skin cancer (NMSC) in patients with skin of color, including Hispanic, African American, and Asian patients. MATERIALS AND METHODS: A complete PubMed search was conducted spanning dates from 1947 to June 2017 yielding a total of 185 manuscripts, from which 45 were included in this review. RESULTS: Relative to Caucasians, NMSC, comprised squamous cell carcinoma and basal cell carcinoma, has unique demographic and clinical features in African Americans, Hispanics, and Asians. CONCLUSION: Familiarization with these unique presentations of skin cancer in skin of color is imperative to accurate identification and treatment of cutaneous malignancies in these populations and ultimately to improved disease-related outcomes.

Eccrine Porocarcinoma: New Insights and a Systematic Review of the Literature.

BACKGROUND: Eccrine porocarcinoma (EPC) is a rare cutaneous neoplasm with high potential for morbidity and mortality. Due to its rarity, there is a paucity of data profiling diagnosis, work-up, and management. OBJECTIVE: To consolidate reported information on demographics, diagnostics, clinical behavior, treatment modalities, and patient outcomes in EPC to provide a reference tool to optimize diagnosis and management. METHODS: A comprehensive PubMed search was performed from 1963 to November 2017 using PRISMA guidelines. This yielded 155 articles detailing 206 cases of porocarcinoma. RESULTS: Eccrine porocarcinoma most often presents in elderly patients on the head and neck or lower limbs. Metastatic disease at presentation is not uncommon (22%). Primary tumor location is significantly correlated with presence of metastasis (p = .038). The most common treatment is excision followed by Mohs micrographic surgery (MMS), although the outcomes after MMS were superior to those after surgical excision. CONCLUSION: This systematic review of individual patient data reveals that all patients should have a histological diagnosis with imaging considered for high-risk cases. Primary tumor location should also be considered in diagnostic and therapeutic decision-making. Although wide local excision (WLE) is currently the first-line treatment, MMS is becoming increasingly used, with evidence indicating improved outcomes as compared to those seen with WLE.

Control of C-H Bond Activation by Mo-Oxo Complexes: pKa or Bond Dissociation Free Energy (BDFE)?

A density functional theory (DFT) study (BMK/6-31+G(d)) was initiated to investigate the activation of benzylic carbon-hydrogen bonds by a molybdenum-oxo complex with a potentially redox noninnocent supporting ligand-a simple mimic of the active species of the enzyme ethylbenzene dehydrogenase (EBDH)-through deprotonation (C-H bond heterolysis) or hydrogen atom abstraction (C-H bond homolysis) routes. Activation free-energy barriers for neutral and anionic Mo-oxo complexes were high, but lower for anionic complexes than neutral complexes. Interesting trends as a function of substituents were observed that indicated significant Hδ+ character in the transition states (TS), which was further supported by the preference for [2 + 2] addition over HAA for most complexes. Hence, it was hypothesized that C-H activation by these EBDH mimics is controlled more by the pKa than by the bond dissociation free energy of the C-H bond being activated. Therefore, the results suggest promising pathways for designing more efficient and selective catalysts for hydrocarbon oxidation based on EBDH active-site mimics.

Pelvic Organ Prolapse in Ehlers-Danlos Syndrome.

Ehlers-Danlos syndrome (EDS) is a hereditary tissue and collagen synthesis disorder that can predispose patients to gynecologic and obstetric complications. Female patients often suffer from bothersome pelvic floor disorders, but due to the medical complexity of EDS, special considerations are needed for the treatment of pelvic organ prolapse and associated incontinence. In this paper, we present three unique cases of pelvic organ prolapse (POP) in EDS patients and delve deeper into the multidisciplinary approach involving urogynecology, rheumatology, physiatry, gastroenterology, and anesthesiology required to appropriately manage this condition.

Pediatric genitourinary tumors: Distribution, demographics, and outcomes.

Importance: The diversity of pediatric genitourinary malignancies requires a timely resource detailing tumor characteristics and survival. Objective: To determine the incidence, demographics, and outcomes of all pediatric genitourinary tumors within the United States. Methods: A population-based search for patients diagnosed with genitourinary cancers under age 15 was performed using the National Cancer Institute's Surveillance, Epidemiology, and End Results 18 registry. Information on primary tumor location, histologic type, patient age, sex, year of diagnosis, race, treatment, cause of death, and survival months was extracted. Descriptive epidemiological and survival statistics were calculated for all variables. Results: A total of 4576 cases from 1973 through 2015 were identified. The most common primary tumor sites were the kidney (80.3%), testis (12.3%), bladder (2.8%), and vagina (1.5%). Nephroblastoma (87.9%) and sarcoma (3.4%) were the most common renal malignancies. Rhabdomyosarcoma was common in the vagina, bladder, and testis at rates of 66.2%, 61.2%, and 24.6%, respectively. Germ cell tumors (71.0%) were the most common primary tumor of the testis. Ten-year overall survival (OS) for renal nephroblastoma and sarcoma was 88% and 82%, respectively. Ten-year OS for RMS of the testis was 91%, the bladder was 79%, the vagina was 79%, and the prostate was 56%. Germ cell tumor 10-year OS were 96% in the testis and 100% in the vagina. Interpretation: A better understanding of the overall distribution and outcomes associated with pediatric genitourinary cancers allows physicians to best understand the patient's disease in the context of current frequency in a genitourinary setting and reported outcomes.

Influence of the Greater Protein Environment on the Electrostatic Potential in Metalloenzyme Active Sites: The Case of Formate Dehydrogenase.

The Mo/W-containing metalloenzyme formate dehydrogenase (FDH) is an efficient and selective natural catalyst that reversibly converts CO2 to formate under ambient conditions. In this study, we investigate the impact of the greater protein environment on the electrostatic potential (ESP) of the active site. To model the enzyme environment, we used a combination of classical molecular dynamics and multiscale quantum-mechanical (QM)/molecular-mechanical (MM) simulations. We leverage charge shift analysis to systematically construct QM regions and analyze the electronic environment of the active site by evaluating the degree of charge transfer between the core active site and the protein environment. The contribution of the terminal chalcogen ligand to the ESP of the metal center is substantial and dependent on the chalcogen identity, with similar, less negative ESPs for Se and S terminal chalcogens in comparison to O regardless of whether the metal is Mo or W. The orientation of the side chains and conformations of the cofactor also affect the ESP, highlighting the importance of sampling dynamic fluctuations in the protein. Overall, our observations suggest that the terminal chalcogen ligand identity plays an important role in the enzymatic activity of FDH, suggesting opportunities for a rational bioinspired catalyst design.

A Prospective Pilot Study Investigating Performance of 18F-Fluciclovine PET Imaging for Detection of Prostate Cancer 2 Years Following Primary Partial Gland Cryoablation.

Purpose: The goal of partial gland ablation (PGA) is to eradicate focal lesions of clinically significant prostate cancer (csPCa) with minimal adverse impact on functional outcomes. The primary objective of this study is to characterize the performance of 18F-Fluciclovine PET imaging for detection of prostate cancer following PGA. Materials and Methods: Subjects 2 years following primary partial gland cryoablation (PPGCA) were invited to participate in an IRB-approved study providing they met the following inclusion criteria: a single reported mpMRI region of interest (ROI) concordant with biopsy Gleason Grade Group (GGG) < 4, no gross extra-prostatic extension on mpMRI, and no GGG > 1 or GGG 1 with a core length > 6 mm on contralateral systematic biopsy. 18F-Fluciclovine PET MRI imaging of the prostate was performed followed by in and out-of-field biopsies. Results: Twenty-seven men who met eligibility criteria participated in the prospective study. In-field and out-of-field csPCa recurrence rate was 7.4% and 22.2%, respectively. The sensitivity and positive predictive value of mpMRI and PET imaging did not reach performance to reliably inform who should undergo prostate biopsy. Conclusion: At 2 years following PPGCA, the rate of in-field csPCa was exceedingly low indicating a limited role for imaging to inform in-field biopsy decisions. The csPCa detection rate of out-of-field recurrence was 22% which provides an opportunity for imaging to inform out-of-field biopsy decisions. Based on our findings, 18F-Fluciclovine PET MRI cannot be used to inform who should undergo out-of-field prostate biopsy at 2 years following PPGCA.

Harder, better, faster, stronger: Large-scale QM and QM/MM for predictive modeling in enzymes and proteins.

Computational prediction of enzyme mechanism and protein function requires accurate physics-based models and suitable sampling. We discuss recent advances in large-scale quantum mechanical (QM) modeling of biochemical systems that have reduced the cost of high-accuracy models. Tradeoffs between sampling and accuracy have motivated modeling with molecular mechanics (MM) in a multiscale QM/MM or iterative approach. Limitations to both conventional density-functional theory and classical MM force fields remain for describing noncovalent interactions in comparison to experiment or wavefunction theory. Because predictions of enzyme action (i.e. electrostatics), free energy barriers, and mechanisms are sensitive to the protocol and embedding method in QM/MM, convergence tests and systematic methods for quantifying QM-level interactions are a needed, active area of development.

Evaluation of Bowel Function Following Radical Cystectomy and Urinary Diversion Using Two Validated Questionnaires: What Are the Effects on Quality of Life?

OBJECTIVE: To assess both short- and long-term constipation symptoms and their impact on quality of life in patients who underwent radical cystectomy (RC) with three different types of urinary diversion: orthotopic neobladder (ONB), continent cutaneous diversion (CCD), and ileal conduit (IC). MATERIALS AND METHODS: The validated Patient Assessment of Constipation Symptoms (PAC-SYM) and Patient Assessment of Constipation Quality of Life (PAC-QOL) questionnaires were administered to all patients at follow-up greater than 30 days from surgery. Clinical and pathological characteristics were prospectively recorded in an institutional review board approved bladder cancer database. Using multivariable linear regression analyses, we determined significant predictors of improved constipation symptoms and quality of life scores. RESULTS: A total of 198 patients completed 255 PAC-SYM and PAC-QOL questionnaires with a median follow-up time of 1.7 years (IQR: 0.7 - 3.0 years). ONB, CCD, and IC were performed in 78%, 5.5%, and 16.5% of patients, respectively. Higher bowel function scores (i.e. worse symptoms) were noted at 3 months post-operatively, while these scores significantly improved over time for PAC-SYM total score (P = .004), abdominal subscore (P = .001), and rectal subscore (P = .018). On multivariable analysis, we found that patients <70 years old (B -2.1, P = .004), with follow-up >1 year (B -4.8, P = .001), and who received an IC (B -2.4, P = .02) had significantly lower PAC-SYM scores. CONCLUSION: Patients have few constipation symptoms and are overall satisfied with their bowel function at long-term follow-up after RC. While patients with IC have significantly fewer constipation symptoms compared to those with ONB or CCD, all patients had significant improvement one year after the surgery.

Adult genitourinary sarcoma: A population-based analysis of clinical characteristics and survival.

BACKGROUND: Sarcomas of the genitourinary (GU) tract are exceedingly rare, accounting for just 1% to 2% of malignancies treated by urologic surgeons. We perform a thorough investigation of incidence and mortality in the United States using the Surveillance, Epidemiology, and End Results (SEER) database. PATIENTS AND METHODS: The SEER 18 database was used to identify patients diagnosed with genitourinary sarcoma over the age of 16. Data on demographics and tumor characteristics were collected. Survival analysis was performed on the most common primary tumor sites. RESULTS: The search identified 3,007 patients with GU sarcomas from 1973 to 2015. In order of descending incidence, tumors presented in the bladder, kidney, paratestis, and scrotum. Amongst sarcomas arising in the bladder, leiomyosarcomas exhibited the longest median survival time (overall survival (OS) 62 months), while carcinosarcomas had the shortest (OS 9 months). Metastatic disease decreased leiomyosarcoma OS to 3 months. When comparing renal tumors, liposarcomas had the longest median survival time (OS 45 months) and carcinosarcomas had the shortest (OS 6 months). Older age (P < 0.001 and P = 0.015) and T4 disease (P = 0.005 and P < 0.001) predicted for worse survival amongst bladder and renal sarcomas, respectively. High tumor grade (P < 0.001) and node positive disease (P = 0.024) also affected survival amongst renal tumors. CONCLUSIONS: Tumors most commonly present in the bladder, kidney, paratestis, and scrotum, with kidney sarcomas having markedly dismal survival outcomes. Survival of identical histologic types varied by primary tumor location, suggesting that treatment strategies should be refined by type of sarcoma and primary tumor location within the GU tract.

Neoadjuvant Chemotherapy in Variant Histology Bladder Cancer: Current Evidence.

The role of neoadjuvant chemotherapy in variant histology bladder cancers has yet to be validated in randomized control trials. Several case series have reported experience with NAC in the setting of variant histology. PATIENT SUMMARY: We reviewed outcomes for patients with variant histology muscle-invasive bladder cancer who received chemotherapy before cystectomy. Outcomes varied significantly in the current literature. The best outcomes are associated with neoadjuvant chemotherapy (NAC) for small cell variants, while there is potential benefit with the use of NAC for squamous cell and adenocarcinoma variants.

Occult Nodal Metastases in Patients Down-Staged to Nonmuscle Invasive Disease Following Neoadjuvant Chemotherapy.

OBJECTIVES: To evaluate the risk of occult nodal metastasis in patients with muscle invasive bladder cancer who exhibit a complete or partial clinical response to neoadjuvant chemotherapy (NAC) and assess a potential role for "bladder sparing" management given that the gold standard treatment, radical cystectomy (RC), is associated with high morbidity. METHODS: We queried the National Cancer Database for bladder cancer from 2004 to 2013 including patients with cT2-4aN0M0 bladder cancer who underwent multiagent NAC followed by RC and pelvic lymphadenectomy and excluding patients with nonurothelial predominant histology and those undergoing partial cystectomy. Student's t test was used to evaluate patients' demographics, presence of co-morbid conditions, and pathologic findings, notably the presence of lymphovascular invasion and variant histology. RESULTS: We identified 17,917 patients who underwent RC. Of these, 14.9% (n = 2673) received NAC before RC. About 13.1% and 14.5% of patients had complete (ypT0) and partial (ypTa, Tis, and T1) pathologic response, respectively. These 14.7% of cT2, 9.0% of cT3, and 6.9% of cT4 patients exhibited pT0 status on final pathology. And 4.9% of complete and 5.4% of partial responders demonstrated occult nodal metastases. Age, sex, ethnicity, the presence of co-morbidities, LVI, and variant histology were not significantly associated with occult nodal metastasis. CONCLUSION: While bladder preservation may be a viable option in patients who are carefully selected and closely followed after NAC, patients undergoing NAC may be at risk of occult disease outside of the bladder despite an otherwise clinical complete response diagnosed with cross-sectional imaging, cystoscopy, TURBT, and cytology.

Predictors of Device-related Complications After Exchange of the Pressure-regulating Balloon in Men With an Artificial Urinary Sphincter.

OBJECTIVE: To identify patient and component specific factors that predispose patients to device-related complications when undergoing pressure-regulating balloon (PRB) exchange in men with an artificial urinary sphincter (AUS). METHOD: From 2009 to 2018, 55 patients underwent AUS revision with placement of a higher pressure 71-80 cm H2O PRB to treat recurrent stress incontinence. Patient demographics, perioperative data, and postoperative outcomes were examined and multivariable logistic regression analyses performed to identify predictors of erosion and mechanical failure. RESULT: After a median follow-up of 26.4 months (range: 6-103.7 months), 21 of 55 (38.1%) patients developed a device-related complication that required operative repair or removal of the AUS. Four (7.3%) patients developed erosion after the PRB pressure increase and 5 patients showed evidence of impending erosion on follow-up and underwent successful revision surgery. Twelve patients developed mechanical failure (cuff leak, n = 7; pump malfunction, n =4; unidentified fluid loss, n = 1). Multivariable logistic regression analysis found that increasing body mass index was a predictor of mechanical failure. Hypertension and lower body mass index were found to increase the risk of cuff erosion whereas radiotherapy was not. CONCLUSION: In the carefully selected patient, PRB exchange can be performed to treat recurrent incontinence in patients with an AUS, including those treated with pelvic radiotherapy. Our data suggest that this technique is susceptible to a high rate of revision surgery. As such, when revising a functional AUS system, meticulous preoperative screening, comprehensive informed consent, and follow-up protocols are essential in minimizing adverse events.