Backtracked and paused transcription initiation intermediate of Escherichia coli RNA polymerase.

Initiation is a highly regulated, rate-limiting step in transcription. We used a series of approaches to examine the kinetics of RNA polymerase (RNAP) transcription initiation in greater detail. Quenched kinetics assays, in combination with gel-based assays, showed that RNAP exit kinetics from complexes stalled at later stages of initiation (e.g., from a 7-base transcript) were markedly slower than from earlier stages (e.g., from a 2- or 4-base transcript). In addition, the RNAP-GreA endonuclease accelerated transcription kinetics from otherwise delayed initiation states. Further examination with magnetic tweezers transcription experiments showed that RNAP adopted a long-lived backtracked state during initiation and that the paused-backtracked initiation intermediate was populated abundantly at physiologically relevant nucleoside triphosphate (NTP) concentrations. The paused intermediate population was further increased when the NTP concentration was decreased and/or when an imbalance in NTP concentration was introduced (situations that mimic stress). Our results confirm the existence of a previously hypothesized paused and backtracked RNAP initiation intermediate and suggest it is biologically relevant; furthermore, such intermediates could be exploited for therapeutic purposes and may reflect a conserved state among paused, initiating eukaryotic RNA polymerase II enzymes.

Overcoming barriers to immediate penile implant salvage surgery: a narrative review.

Background and Objective: Since immediate salvage (IS) surgery for infected penile prosthesis (PP) was introduced nearly 30 years ago, an abundance of evidence has emerged in support of its use. IS remains underutilized by the modern urologist despite its distinct advantages. While some medical literature proposes reasons for the underuse of IS, no comprehensive review attempts to address the numerous factors limiting its implementation. Our objective is to analyze the barriers to IS surgery for infected PP with the goal of expanding utilization of this technique through a practical and standardized approach for treating urologists. Methods: A narrative review of available English, peer-reviewed, medical literature relevant to the barriers to IS was completed. Searches were expanded to include literature from surgical specialties in general if hypothesized barriers were incompletely described in available PP publications. Key Content and Findings: The major barriers that are likely contributing to the low rates of IS for PP surgery can be broadly classified into three major categories: institutional/systemic, medical/surgical, and patient preference. Institutional/systemically driven barriers include surgeon comfort with PP surgery, low national availability of urologists, inaccessibility of prosthetics or critical ancillary staff at the time of patient presentation and limited operating room (OR) access. Medical/surgical barriers primarily relate to reinfection fears, perceived contraindications to IS, and overall patient stability at the time of presentation. Patient preference factors inhibiting IS involve loss of trust in the medical team, psychosocial distress, dissatisfaction with the initial device prior to infection and anxiety regarding postoperative recovery. Many of the identified barriers can be overcome with increased surgical training, improved patient and surgeon understanding of PP infection, or precautionary planning. Conclusions: Of the factors that contribute to low utilization of IS, many are misunderstood or unknown. Recognition of these barriers may equip urologists to provide better care to patients with prosthesis infection.

Comparison of Perioperative Outcomes for Radical Nephrectomy Based on Surgical Approach for Masses Greater Than 10 cm.

Introduction and Objective: Robot-assisted radical nephrectomy (RRN) is increasingly utilized as an alternative to laparoscopic radical nephrectomy (LRN), but there are concerns over costs and objective benefit. In the setting of very large renal masses (>10 cm), comparison between techniques is limited and it is unclear whether a robotic approach confers any perioperative benefit over LRN or open radical nephrectomy (ORN). In this study, perioperative outcomes of RRN, LRN, and ORN for very large renal masses are compared. Methods: Using the National Cancer Database, patients were identified who underwent radical nephrectomy for kidney tumors >10 cm diagnosed from 2010 to 2015. Patients were analyzed according to surgical approach. Perioperative outcomes, including conversion to open, length of stay, readmission rates, positive surgical margins, and 30- and 90-day mortality were compared among cohorts. Results: A total of 9288 patients met inclusion criteria (RRN = 842, LRN = 2326, ORN = 6120). Compared with ORN, recipients of RRN or LRN had similar rates of 30-day readmission and 30- and 90-day mortality. Length of hospital stay was significantly shorter in RRN (-1.73 days ±0.19; p < 0.0001) and LRN (-1.40 days ±0.12; p < 0.0001) compared with ORN. LRN had a higher rate of conversion to open compared with RRN (odds ratio 1.48; 95% confidence interval 1.10-1.98; p = 0.0087). Conversion to open from RRN or LRN added 1.3 additional days of inpatient stay. Over the study period, RRN use increased from 4.1% to 14.8%, LRN from 20.9% to 25.6%, whereas ORN use decreased from 75% to 59.6%. Conclusions: Minimally invasive approaches are increasingly utilized in very large renal masses. RRN has lower rates of conversion to open but produces comparable perioperative outcomes to LRN. Minimally invasive approaches have a shorter length of inpatient stay but otherwise report similar surgical margin status, readmission rates, and mortality rates compared with ORN.