Sarcopenia and frailty in patients undergoing transcatheter aortic valve replacement.

BACKGROUND: Skeletal muscle mass (SMM) plays a crucial role in risk assessment in transcatheter aortic valve replacement (TAVR) candidates, yet it remains underutilized. Traditional methods focus on weakness or performance but omit SMM. This study compared traditional and novel markers of sarcopenia and frailty in terms of their ability to predict adverse outcomes post-TAVR. METHODS: Three risk models were evaluated for the composite outcome of perioperative complications, 1-year rehospitalization, or 1-year mortality: (1) sarcopenia by combining low muscle mass (LMM) and weakness/performance assessed by hand grip strength or gait speed; (2) frailty by an Adapted Green score; and (3) frailty by the Green-SMI score incorporating LMM by multilevel opportunistic pre-TAVR thoracic CT segmentation. RESULTS: In this study we included 184 eligible patients from January to December of 2018, (96.7%) of which were balloon expandable valves. The three risk models identified 22.8% patients as sarcopenic, 63.6% as frail by the Adapted Green score, and 53.8% as frail by the Green-SMI score. There were higher rates of the composite outcome in patients with sarcopenia (54.8%) and frailty (41.9% with the Adapted Green and 50.5% with the Green-SMI score) compared to their nonsarcopenic (30.3%) and nonfrail counterparts (25.4% with the Adapted Green and 18.8% with the Green-SMI score). Sarcopenia and frailty by Green-SMI, but not by the Adapted Green, were associated with higher risks of the composite outcome on multivariable adjustment (HR 2.2 [95% CI: 1.25-4.02], P = .007 and HR 3.4 [95% CI: 1.75-6.65], P < .001, respectively). CONCLUSIONS: The integration of preoperative CT-based SMM to a frailty score significantly improves the prediction of adverse outcomes in patients undergoing TAVR.

The impact of metastatic sites on survival Rates and predictors of extended survival in patients with metastatic pancreatic cancer.

BACKGROUND OBJECTIVES: The aim of this study was to determine the role of site-specific metastatic patterns over time and assess factors associated with extended survival in metastatic PDAC. Half of all patients with pancreatic ductal adenocarcinoma (PDAC) present with metastatic disease. The site of metastasis plays a crucial role in clinical decision making due to its prognostic value. METHODS: We examined 56,757 stage-IV PDAC patients from the National Cancer Database (2016-2019), categorizing them by metastatic site: multiple, liver, lung, brain, bone, carcinomatosis, or other. The site-specific prognostic value was assessed using log-rank tests while time-varying effects were assessed by Aalen's linear hazards model. Factors associated with extended survival (>3years) were assessed with logistic regression. RESULTS: Median overall survival (mOS) in patients with distant lymph node-only metastases (9.0 months) and lung-only metastases (8.1 months) was significantly longer than in patients with liver-only metastases (4.6 months, p < 0.001). However, after six months, the metastatic site lost prognostic value. Logistic regression identified extended survivors (3.6 %) as more likely to be younger, Hispanic, privately insured, Charlson-index <2, having received chemotherapy, or having undergone primary or distant site surgery (all p < 0.001). CONCLUSION: While synchronous liver metastases are associated with worse outcomes than lung-only and lymph node-only metastases, this predictive value is diminished after six months. Therefore, treatment decisions beyond this time should not primarily depend on the metastatic site. Extended survival is possible in a small subset of patients with favorable tumor biology and good conditional status, who are more likely to undergo aggressive therapies.

Analysis of laboratory markers in body contouring procedures after bariatric surgery does not indicate particular risks for perioperative complications.

BACKGROUND: Body contouring surgery after massive weight loss is associated with different risk factors. Wound healing disorders and seromas commonly occur postoperatively. Bariatric interventions lead to massive weight loss with excess skin and soft tissue. In this study, perioperatively collected laboratory markers of this special patient population were analyzed. METHODS: Fifty-nine patients were analyzed retrospectively regarding bariatric surgery, weight loss, body contouring surgery, laboratory markers, and complication rates. RESULTS: Body contouring surgery (n = 117) was performed in 59 patients. Weight loss was achieved after gastric bypass (40.1%), gastric banding (33.9%), or sleeve gastrectomy (26.0%), with an average of 69.2 kg. The most common body contouring procedure included abdominoplasty (n = 50), followed by thigh lift (n = 29), mammaplasty (n = 19), brachioplasty (n = 14), and upper body lift (n = 5). Analysis of laboratory markers revealed no exceptional and clinically relevant variations. Correlation analysis revealed associations between resection weight, amount of drain fluid, and particular laboratory markers. CONCLUSION: Analysis of perioperative laboratory markers in this special patient population after massive weight loss did not indicate clinically relevant risk factors regardless of the type of bariatric or body contouring surgery. Body contouring surgeries after bariatric interventions prove to be safe and low risk concerning perioperative laboratory markers and postoperative hospitalization.

Improving detection of carcinoma in situ in bladder cancer: urinary cytology vs the Xpert® BC Monitor.

OBJECTIVE: To investigate and compare the performance of urinary cytology and the Xpert BC Monitor test in the detection of bladder cancer in various clinically significant patient cohorts, including patients with carcinoma in situ (CIS), in a prospective multicentre setting, aiming to identify potential applications in clinical practice. PATIENTS AND METHODS: A total of 756 patients scheduled for transurethral resection of bladder tumour (TURBT) were prospectively screened between July 2018 and December 2020 at six German University Centres. Central urinary cytology and Xpert BC Monitor tests were performed prior to TURBT. The diagnostic performance of urinary cytology and the Xpert BC Monitor was evaluated according to sensitivity (SN), specificity (SC), negative predictive value (NPV) and positive predictive value (PPV). Statistical comparison of urinary cytology and the Xpert BC Monitor was conducted using the McNemar test. RESULTS: Of 756 screened patients, 733 (568 male [78%]; median [interquartile range] age 72 [62-79] years) were included. Bladder cancer was present in 482 patients (65.8%) with 258 (53.5%) high-grade tumours. Overall SN, SC, NPV and PPV were 39%, 93%, 44% and 92% for urinary cytology, and 75%, 69%, 59% and 82% for the Xpert BC Monitor. In patients with CIS (concomitant or solitary), SN, SC, NPV and PPV were 59%, 93%, 87% and 50% for urinary cytology, and 90%, 69%, 95% and 50% for the Xpert BC Monitor. The Xpert BC Monitor missed four tumours (NPV = 98%) in patients with solitary CIS, while potentially avoiding 63.3% of TURBTs in inconclusive or negative cystoscopy and a negative Xpert result. CONCLUSION: Positive urinary cytology may indicate bladder cancer and should be taken seriously. The Xpert BC Monitor may represent a useful diagnostic tool for correctly identifying patients with solitary CIS and unsuspicious or inconclusive cystoscopy.

QM/MM Free Energy Calculations of Long-Range Biological Protonation Dynamics by Adaptive and Focused Sampling.

Water-mediated proton transfer reactions are central for catalytic processes in a wide range of biochemical systems, ranging from biological energy conversion to chemical transformations in the metabolism. Yet, the accurate computational treatment of such complex biochemical reactions is highly challenging and requires the application of multiscale methods, in particular hybrid quantum/classical (QM/MM) approaches combined with free energy simulations. Here, we combine the unique exploration power of new advanced sampling methods with density functional theory (DFT)-based QM/MM free energy methods for multiscale simulations of long-range protonation dynamics in biological systems. In this regard, we show that combining multiple walkers/well-tempered metadynamics with an extended system adaptive biasing force method (MWE) provides a powerful approach for exploration of water-mediated proton transfer reactions in complex biochemical systems. We compare and combine the MWE method also with QM/MM umbrella sampling and explore the sampling of the free energy landscape with both geometric (linear combination of proton transfer distances) and physical (center of excess charge) reaction coordinates and show how these affect the convergence of the potential of mean force (PMF) and the activation free energy. We find that the QM/MM-MWE method can efficiently explore both direct and water-mediated proton transfer pathways together with forward and reverse hole transfer mechanisms in the highly complex proton channel of respiratory Complex I, while the QM/MM-US approach shows a systematic convergence of selected long-range proton transfer pathways. In this regard, we show that the PMF along multiple proton transfer pathways is recovered by combining the strengths of both approaches in a QM/MM-MWE/focused US (FUS) scheme and reveals new mechanistic insight into the proton transfer principles of Complex I. Our findings provide a promising basis for the quantitative multiscale simulations of long-range proton transfer reactions in biological systems.

[Should we all switch to en-bloc resection of bladder tumours?] / Sollten wir alle zur En Bloc Resektion von Blasentumoren wechseln?

In En-Bloc Resection of Bladder Tumours (ERBT), tumours are not removed in fragments, but are dissected in one layer and, if possible, extracted in one piece. This method represents a significant shift in the surgical management of non-muscle-invasive bladder tumours, providing multiple benefits over the traditional transurethral resection of the bladder (TUR-B). The histological analysis of ERBT specimens is more accurate, enhancing diagnostic precision. Additionally, the presence of detrusor muscle in ERBT specimens is more frequent, indicating a more complete removal of the tumours. Recent years have seen the consolidation of a robust evidence base emphasizing the advantages of ERBT. Notably, a multicentric, prospective randomized trial has recently revealed a significant reduction in recurrence rates at 12 months follow-up compared with TUR-B. Experienced endourologists should explore this technique, as it may soon become the standard of care. The technique's elegance and effectiveness make it too important to be ignored.

Low Muscle Mass by Preprocedural Computed Tomography Is Associated With Worse Short-Term Outcomes in Transcatheter Aortic Valve Replacement Recipients.

Low muscle mass (LMM) is associated with worse outcomes in various clinical situations. Traditional frailty markers have been used for preoperative risk stratification in patients who underwent transcatheter aortic valve replacement (TAVR). However, preoperative imaging provides an opportunity to directly quantify skeletal muscle mass to identify patients at higher risk of procedural complications. We reviewed all TAVR recipients from January to December 2018 and included subjects with preprocedural chest computed tomography. Multi-slice automated measurements of skeletal muscle mass were made from the ninth to twelfth thoracic vertebrae and normalized by height squared to obtain skeletal muscle index (cm2/m2). LMM was defined as the lowest gender-stratified skeletal muscle index tertile. Strength testing was collected during pre-TAVR evaluation. Primary outcome was a composite of perioperative complications, 1-year rehospitalization, or 1-year mortality. In our cohort, 238 patients met inclusion criteria, and 80 (33.6%) were identified to have LMM. Patients with LMM were older with lower body mass index, decreased grip strength, lower hemoglobin A1c, and higher N-terminal pro-brain natriuretic peptide. They had greater rates of the composite outcome and 2-year all-cause mortality, which remained significant on multivariable adjustment (hazard ratio 1.71, 95% confidence interval 1.05 to 2.78, p = 0.030 and hazard ratio 2.31, 95% confidence interval 1.02 to 5.24, p = 0.045, respectively) compared with patients without LMM; there was no significant difference in 5-year all-cause mortality. In conclusion, LMM was associated with an increase in the primary composite outcome and 2-year all-cause mortality in TAVR recipients. Using automatic muscle processing software on pre-TAVR computed tomography scans may serve as an additional preoperative risk stratification tool.

Robotic versus open partial pancreatoduodenectomy (EUROPA): a randomised controlled stage 2b trial.

Background: Open partial pancreatoduodenectomy (OPD) represents the current gold standard of surgical treatment of a wide range of diseases of the pancreatic head but is associated with morbidity in around 40% of cases. Robotic partial pancreatoduodenectomy (RPD) is being used increasingly, yet, no randomised controlled trials (RCTs) of RPD versus OPD have been published, leaving a low level of evidence to support this practice. Methods: This investigator-initiated, exploratory RCT with two parallel study arms was conducted at a high-volume pancreatic centre in line with IDEAL recommendations (stage 2b). Patients scheduled for elective partial pancreatoduodenectomy (PD) for any indication were randomised (1:1) to RPD or OPD with a centralised web-based tool. The primary endpoint was postoperative cumulative morbidity within 90 days, assessed via the Comprehensive Complication Index (CCI). Biometricians were blinded to the intervention, but patients and surgeons were not. The trial was registered prospectively (DRKS00020407). Findings: Between June 3, 2020 and February 14, 2022, 81 patients were randomly assigned to RPD (n = 41) or OPD (n = 40), of whom 62 patients (RPD: n = 29, OPD: n = 33) were analysed in the modified intention to treat analysis. Four patients in the OPD group were randomised, but did not undergo surgery in our department and one patient was excluded in the RPD group due to other reason. Nine patients in the RPD group and 3 patients in the OPD were excluded from the primary analysis because they did not undergo PD, but rather underwent other types of surgery. The CCI after 90 days was comparable between groups (RPD: 34.02 ± 23.48 versus OPD: 36.45 ± 27.65, difference in means [95% CI]: -2.42 [-15.55; 10.71], p = 0.713). The RPD group had a higher incidence of grade B/C pancreas-specific complications compared to the OPD group (17 (58.6%) versus 11 (33.3%); difference in rates [95% CI]: 25.3% [1.2%; 49.4%], p = 0.046). The only complication that occurred significantly more often in the RPD than in the OPD group was clinically relevant delayed gastric emptying. Procedure-related and overall hospital costs were significantly higher and duration of surgery was longer in the RPD group. Blood loss did not differ significantly between groups. The intraoperative conversion rate of RPD was 23%. Overall 90-day mortality was 4.8% without significant differences between RPD and OPD. Interpretation: In the setting of a very high-volume centre, both RPD and OPD can be considered safe techniques. Further confirmatory multicentre RCTs are warranted to uncover potential advantages of RPD in terms of perioperative and long-term outcomes. Funding: Federal Ministry of Education and Research (BMBF: 01KG2010).

Robotic-assisted versus manual Uro Dyna-CT-guided puncture in an ex-vivo kidney phantom.

INTRODUCTION AND OBJECTIVES: Challenging percutaneous renal punctures to gain access to the kidney requiring guidance by cross-sectional imaging. To test the feasibility of robotic-assisted CT-guided punctures (RP) and compare them with manual laser-guided punctures (MP) with Uro Dyna-CT (Siemens Healthcare Solutions, Erlangen, Germany). MATERIAL AND METHODS: The silicon kidney phantom contained target lesions of three sizes. RP were performed using a robotic assistance system (guidoo, BEC GmbH, Pfullingen, Germany) with a robotic arm (LBR med R800, KUKA AG, Augsburg, Germany) and a navigation software with a cone-beam-CT Artis zeego (Siemens Healthcare GmbH, Erlangen, Germany). MP were performed using the syngo iGuide Uro-Dyna Artis Zee Ceiling CT (Siemens Healthcare Solutions). Three urologists with varying experience performed 20 punctures each. Success rate, puncture accuracy, puncture planning time (PPT), and needle placement time (NPT) were measured and compared with ANOVA and Chi-Square Test. RESULTS: One hundred eighteen punctures with a success rate of 100% for RP and 78% for MP were included. Puncture accuracy was significantly higher for RP. PPT (RP: 238 ± 90s, MP: 104 ± 21s) and NPT (RP: 128 ± 40s, MP: 81 ± 18s) were significantly longer for RP. The outcome variables did not differ significantly with regard to levels of investigators' experience. CONCLUSION: The accuracy of RP was superior to that of MP. This study paves the way for first in-human application of this robotic puncture system.

Peritoneal Flap for Lymphocele Prophylaxis Following Robotic-assisted Radical Prostatectomy with Lymph Node Dissection: The Randomised Controlled Phase 3 PELYCAN Trial.

BACKGROUND: Symptomatic lymphoceles (SLCs) after transperitoneal robotic-assisted radical prostatectomy with pelvic lymph node dissection (PLND) are common. Evidence from randomised controlled trials (RCTs) on the impact of peritoneal flaps (PFs) on lymphocele (LC) reduction is inconclusive. OBJECTIVE: To show that addition of PFs leads to a reduction of postoperative SLCs. DESIGN, SETTING, AND PARTICIPANTS: An investigator-initiated, prospective, parallel, double-blinded, adaptive, phase 3 RCT was conducted. Recruitment took place from September 2019 until December 2021; 6-month written survey-based follow-up was recorded. Stratification was carried out according to potential LC risk factors (extended PLND, diabetes mellitus, and anticoagulation) and surgeons; 1:1 block randomisation was used. Surgeons were informed about allocation after completion of the last surgical step. INTERVENTION: To create PFs, the ventral peritoneum was incised bilaterally and fixated to the pelvic floor. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary endpoint was SLCs. Secondary endpoints included asymptomatic lymphoceles (ALCs), perioperative parameters, and postoperative complications. RESULTS AND LIMITATIONS: In total, 860 men were screened and 551 randomised. Significant reductions of SLCs (from 9.1% to 3.7%, p = 0.005) and ALCs (27.2% to 10.3%, p < 0.001) over the follow-up period of 6 mo were observed in the intention-to-treat analysis. Operating time was 11 min longer (p < 0.001) in the intervention group; no significant differences in amount (80 vs 103, p = 0.879) and severity (p = 0.182) of postoperative complications (excluding LCs) were observed. The survey-based follow-up might be a limitation. CONCLUSIONS: This is the largest RCT evaluating PF creation for LC prevention and met its primary endpoint, the reduction of SLCs. The results were consistent among all subgroup analyses including ALCs. Owing to the subsequent reduction of burden for patients and the healthcare system, establishing PFs should become the new standard of care. PATIENT SUMMARY: A new technique-creation of bilateral peritoneal flaps-was added to the standard procedure of robotic-assisted prostatectomy for lymph node removal. It was safe and decreased lymphocele development, a common postoperative complication and morbidity. Hence, it should become a standard procedure.

Quick and safe: why a k-wire-extension-block-fixation of a bony mallet finger is the favoured treatment.

INTRODUCTION: Mallet fingers are the most common tendon injuries of the hand. Bony avulsion distal finger extensor tendon ruptures causing a mallet finger require special attention and management. In this monocentral study, we analyzed the clinical and individual outcomes succeeding minimal invasive k-wire extension block treatment of bony mallet fingers. MATERIALS AND METHODS: In a retrospective study, we sent a self-designed template and a QUICK-DASH score questionnaire to all patients, who were treated because of a bony mallet finger between 2009 and 2022 and fulfilled the inclusion criteria. A total of 244 requests were sent out. 72 (29.5%) patients participated in the study. Forty-five men and twenty-seven women were included. RESULTS: 98.7% (n = 75) of the cases were successfully treated. Patients were highly satisfied with the treatment (median 8.0; SD ± 2.9; range 1.0-10.0). Based on the QUICK-DASH score, all patients showed no difficulties in daily life. The extent of avulsion did not influence the outcome. CONCLUSION: We conclude that the minimally invasive treatment of a bony mallet finger should be offered to every patient, because it is safe, fast, and reliable. Thus, we propose to perform extension-block pinning independently of the articular area.

Framework for a living systematic review and meta-analysis for the surgical treatment of bladder cancer: introducing EVIglance to urology.

Background: Knowledge of current and ongoing studies is critical for identifying research gaps and enabling evidence-based decisions for individualized treatment. However, the increasing number of scientific publications poses challenges for healthcare providers and patients in all medical fields to stay updated with the latest evidence. To overcome these barriers, we aim to develop a living systematic review and open-access online evidence map of surgical therapy for bladder cancer (BC), including meta-analyses. Methods: Following the guidelines provided in the Cochrane Handbook for Systematic Reviews of Interventions and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement, a systematic literature search on uro-oncological therapy in BC will be performed across various literature databases. Within the scope of a meta-analysis and living systematic review, relevant randomized controlled trials will be identified. Data extraction and quantitative analysis will be conducted, along with a critical appraisal of the quality and risk of bias of each study. The available research evidence will be entered into an open-access framework (www.evidencemap.surgery) and will also be accessible via the EVIglance app. Regular semi-automatic updates will enable the implementation of a real-living review concept and facilitate resource-efficient screening. Discussion: A regularly updated evidence map provides professionals and patients with an open-access knowledge base on the current state of research, allowing for decision-making based on recent evidence. It will help identify an oversupply of evidence, thus avoiding redundant work. Furthermore, by identifying research gaps, new hypotheses can be formulated more precisely, enabling planning, determination of sample size, and definition of endpoints for future trials.

Database of segmentations and surface models of bones of the entire lower body created from cadaver CT scans.

The range of applications of digital surface models of the bones in science and industry is wide. Three-dimensional reconstructions of bones are used in biomechanics, biomedical engineering, medical image processing, orthopedics, traumatology, radiology, patient education, anatomy, anthropometry, forensic anthropology, ergonomics, usability and human factors engineering, or accident and injury analysis and prevention. No open access database or repository of skeletal surface models of the full lower extremities exists. Therefore, the objective of this publication was to provide access to consistent complete bone models of the pelvis and lower limbs of multiple subjects, including biometric data. Segmentations and surface models of the bones of the lower extremities of more than twenty subjects were created from open access postmortem whole-body computed tomography scans. The database provides a broad range of applications by giving access to the data of the complete process chain, from the raw medical imaging data through the segmentations to the surface models.

A new bimodal approach for sentinel lymph node imaging in prostate cancer using a magnetic and fluorescent hybrid tracer.

PURPOSE: To obtain initial data on sentinel lymph node (SLN) visualisation by pre-operative magnetic resonance imaging (MRI) and intra-operative bimodal SLN identification using a new magnetic fluorescent hybrid tracer in prostate cancer (PCa) patients. METHODS: Ten patients at > 5% risk for lymph node (LN) invasion were included. The day before surgery, a magnetic fluorescent hybrid tracer consisting of superparamagnetic iron oxide nanoparticles (SPION) and indocyanine green was transrectally injected into the prostate. Five hours after injection, transversal pelvic MRI scans were recorded and T2*-weighed images were screened for pelvic LNs with SPION uptake. Intra-operatively, magnetically active and/or fluorescent SLNs were detected by a handheld magnetometer and near-infrared fluorescence imaging (FI). Extended pelvic lymph node dissection (PLND) and radical prostatectomy completed the surgery. All resected specimens were checked ex situ for magnetic activity and fluorescence and were histopathologically examined. RESULTS: Pre-operative MRI identified 145 pelvic LNs with SPION uptake. In total, 75 (median 6, range 3‒13) magnetically active SLNs were resected, including 14 SLNs not seen on MRI. FI identified 89 fluorescent LNs (median 8.5, range 4‒13) of which 15 LNs were not magnetically active. Concordance of the different techniques was 70% for pre-operative MRI vs. magnetometer-guided PLND and 88% for magnetic vs. fluorescent SLN detection. CONCLUSION: These are the first promising results of bimodal, magnetic fluorescent SLN detection in PCa patients. Our magnetic fluorescent hybrid approach provides the surgeon a pre-operative lymphatic roadmap by using MRI and intra-operative visual guidance through the application of a fluorescent lymphatic agent. The diagnostic accuracy of our new hybrid approach has to be evaluated in further studies. TRIAL REGISTRATION: DRKS00032808. Registered 04 October 2023, retrospectively registered.

Xpert bladder cancer monitor to predict the need for a second TURB (MoniTURB trial).

To determine whether Xpert bladder cancer monitor, a noninvasive PCR-based biomarker test, can predict the need for 2nd transurethral resection of the bladder (TURB) better than clinical assessment. Patients scheduled for TURB were prospectively screened. After initial TURB, patients were assigned to 2nd TURB or follow-up cystoscopy at 3 months (FU) by clinicians' discretion. Central urine cytology and Xpert monitor tests were performed prior to the 1st TURB and 2nd TURB or FU, respectively. Statistical analysis to compare clinical assessment and Xpert monitor comprised sensitivity (SENS), specificity (SPEC), NPV and PPV. Of 756 screened patients, 171 were included (114 with 2nd TURB, 57 with FU). Residual tumors were detected in 34 patients who underwent 2nd TURB, and recurrent tumors were detected in 2 patients with FU. SENS and SPEC of Xpert monitor were 83.3% and 53.0%, respectively, PPV was 32.6% and NPV was 92.1%. Clinical risk assessment outperformed Xpert monitor. In patients with pTa disease at initial TURB, Xpert monitor revealed a NPV of 96%. Xpert monitor was not superior than clinical assessment in predicting the need for 2nd TURB. It might be an option to omit 2nd TURB for selected patients with pTa disease.

Reinvestigating the clinical relevance of the m6A writer METTL3 in urothelial carcinoma of the bladder.

METTL3 is the major writer of N6-Methyladenosine (m6A) and has been associated with controversial roles in cancer. This is best illustrated in urothelial carcinoma of the bladder (UCB), where METTL3 was described to have both oncogenic and tumor-suppressive functions. Here, we reinvestigated the role of METTL3 in UCB. METTL3 knockout reduced the oncogenic phenotype and m6A levels of UCB cell lines. However, complete depletion of METTL3/m6A was not achieved due to selection of cells expressing alternative METTL3 isoforms. Systematic vulnerability and inhibitor response analyses suggested that uroepithelial cells depend on METTL3 for viability. Furthermore, expression and survival analyses of clinical data revealed a complex role for METTL3 in UCB, with decreased m6A mRNA levels in UCB tumors. Our results suggest that METTL3 expression may be a suitable diagnostic UCB biomarker, as the enzyme promotes UCB formation. However, the suitability of the enzyme as a therapeutic target should be evaluated carefully.

Quinone Catalysis Modulates Proton Transfer Reactions in the Membrane Domain of Respiratory Complex I.

Complex I is a redox-driven proton pump that drives electron transport chains and powers oxidative phosphorylation across all domains of life. Yet, despite recently resolved structures from multiple organisms, it still remains unclear how the redox reactions in Complex I trigger proton pumping up to 200 Å away from the active site. Here, we show that the proton-coupled electron transfer reactions during quinone reduction drive long-range conformational changes of conserved loops and trans-membrane (TM) helices in the membrane domain of Complex I from Yarrowia lipolytica. We find that the conformational switching triggers a π → α transition in a TM helix (TM3ND6) and establishes a proton pathway between the quinone chamber and the antiporter-like subunits, responsible for proton pumping. Our large-scale (>20 µs) atomistic molecular dynamics (MD) simulations in combination with quantum/classical (QM/MM) free energy calculations show that the helix transition controls the barrier for proton transfer reactions by wetting transitions and electrostatic effects. The conformational switching is enabled by re-arrangements of ion pairs that propagate from the quinone binding site to the membrane domain via an extended network of conserved residues. We find that these redox-driven changes create a conserved coupling network within the Complex I superfamily, with point mutations leading to drastic activity changes and mitochondrial disorders. On a general level, our findings illustrate how catalysis controls large-scale protein conformational changes and enables ion transport across biological membranes.