Rick Popert

P2X RECEPTORS AND THEIR ROLE IN FEMALE IDIOPATHIC DETRUSOR INSTABILITY

PURPOSE It is clear from previous studies that adenosine triphosphate is released as a contractile co-transmitter with acetylcholine from parasympathetic nerves supplying the mammalian bladder but the physiological significance of ligand gated purinergic P2X receptors in human bladder innervation has not been adequately investigated. We examined the role of these receptors in female patients with idiopathic detrusor instability. MATERIALS AND METHODS Female patients with idiopathic detrusor instability were recruited for cystoscopy and bladder biopsy with ethics approval. Control tissue was obtained from age and sex matched patients with a urodynamically proved stable bladder. We obtained 4 bladder biopsies per patient from the posterior wall. Samples were analyzed in an organ bath for functional studies of the detrusor muscle to assess the purinergic contribution to its contraction. In addition, we performed quantitative analysis using reverse transcriptase-polymerase chain reaction and immunohistochemical localization of P2X receptors. RESULTS In patients with idiopathic detrusor instability detrusor P2X2 receptors were significantly elevated, while other P2X receptor subtypes were significantly decreased. A purinergic component of nerve mediated contractions was not detected in control female bladder biopsy specimens but there was a significant component in unstable bladder specimens. It was particularly prominent at stimulation frequencies of 2 to 16 Hz. which are likely to be most relevant physiologically. Approximately 50% of nerve mediated contractions were purinergic in idiopathic detrusor instability cases. CONCLUSIONS In patients with idiopathic detrusor instability there is abnormal purinergic transmission in the bladder, which may explain symptoms. This pathway may be a novel target for the pharmacological treatment of overactive bladder.

A quantitative analysis of purinoceptor expression in the bladders of patients with symptomatic outlet obstruction.

Objective To compare the expression of the seven known P2X receptors in human bladder from male patients with detrusor instability caused by symptomatic bladder outlet obstruction with that from control bladders, using a quantitative reverse transcription‐polymerase chain reaction (RT‐PCR) method.

A quantitative analysis of purinoceptor expression in human fetal and adult bladders

PURPOSE In adults there is evidence that adenosine triphosphate acting at P2X receptors functions as a co-transmitter at vesical smooth muscle. The contractile mechanisms of human fetal bladder have been studied to a limited extent and it remains undetermined whether P2X receptors contribute. We compared the expression of the 7 known P2X receptors in fetal and adult human bladders using a quantitative polymerase chain reaction (PCR) based method. MATERIALS AND METHODS Real-time quantitative reverse transcriptase-PCR provides a system for the detection and analysis of RNA. Four complete cadaver fetal bladders were obtained at 16 weeks to full-term gestation and divided into a total of 12 segments. Adult bladder samples were obtained from 4 patients requiring bladder biopsy. Total RNA was extracted from each sample and 10 ng. were used for individual PCR reactions. An ABI 7700 machine (PE Applied Biosystems, California) determined expression levels of the 7 P2X genes in total RNA. RESULTS In adult bladders P2X1 was by far the predominant purinergic receptor at the messenger RNA level. The remaining purinergic receptors were consistently present in the order P2X1 >> P2X4 > P2X7 >> P2X5 > P2X2 >> P2X3 = P2X6 = 0. In fetal bladders the expression of P2X1 transcripts was much lower than in adult bladders, and P2X4 and P2X7 were also present. The rank order of the P2X transcript level was P2X1 = P2X4 > P2X7 >> P2X5 >> P2X2 >> P2X3 = P2X6 = 0. With increasing gestation the P2X receptor transcript level (expression) shifted from the dome to the body of the bladder. CONCLUSIONS P2X1 is the predominant purinoceptor subtype in adult human bladders, consistent with pharmacological evidence. The fetal expression of all P2X receptor transcripts is much lower than in adults, suggesting that purinergic transmission is of less importance. However, there are also several marked developmental changes in purinoceptor expression in the bladder, in that P2X4 is expressed in developing bladders at relatively high levels. There is also a marked developmental change in the regional distribution of purinoceptors. These changes are likely to reflect the changing role of purinergic transmission in the control of bladder motility during fetal maturation.

Role of Cell-Free Plasma DNA as a Diagnostic Marker for Prostate Cancer

Abstract: Recent evidence has shown elevated levels of cell‐free plasma DNA in cancer patients. The aim of the present study was to quantify and compare the levels of cell‐free plasma DNA in patients with prostate cancer, prostatic intraepithelial neoplasia (PIN), and benign prostatic hypertrophy (BPH) to examine if it offered a useful diagnostic test. Blood samples were obtained from 37 patients attending a clinic for prostate biopsies. Samples were taken prior to biopsy, within 1 hour of the biopsy, and then 2 weeks later. DNA was extracted using a QIAamp blood kit (Qiagen) and plasma DNA measured, in genome equivalents/milliliter plasma (GE/mL), using real‐time quantitative PCR for the β‐globin gene. Prior to biopsy, plasma DNA concentration in BPH patients was 936 GE/mL (median; range: 633–2074 GE/mL), while cancer and PIN patients had significantly higher levels of DNA at 1734 GE/mL (median; range: 351–3131 GE/mL; P= 0.01) and 1780 GE/mL (median; range: 1514‐2732 GE/mL; P= 0.04), respectively. Comparison of plasma DNA concentration before and after biopsy showed that 60 minutes after biopsy values were significantly higher in both BPH (1494 GE/mL; range: 613‐2522 GE/mL; P= 0.029) and cancer (2758; range: 1498‐5226 GE/mL; P= 0.007) patients. ROC analysis of the data indicated a sensitivity of 85% and a specificity of 73% when DNA concentration of 1000 GE/mL was taken as an indicator of malignancy or PIN. The data suggest that quantification of cell‐free plasma DNA may have an important diagnostic role in distinguishing benign and malignant prostate disease.

Definitions of terms, processes and a minimum dataset for transperineal prostate biopsies: a standardization approach of the Ginsburg Study Group for Enhanced Prostate Diagnostics.

To define terms and processes and agree on a minimum dataset in relation to transperineal prostate biopsy procedures and enhanced prostate diagnostics. To identify the need for further evaluation and establish a collaborative research practice.

Indications, results and safety profile of transperineal sector biopsies (TPSB) of the prostate: a single centre experience of 634 cases

To describe a protocol for transperineal sector biopsies (TPSB) of the prostate and present the clinical experience of this technique in a UK population.

Diagnostic accuracy of magnetic resonance imaging (MRI) prostate imaging reporting and data system (PI-RADS) scoring in a transperineal prostate biopsy setting

To determine the sensitivity and specificity of multiparametric magnetic resonance imaging (mpMRI) for significant prostate cancer with transperineal sector biopsy (TPSB) as the reference standard.

Evaluation of the Learning Curve for Holmium Laser Enucleation of the Prostate Using Multiple Outcome Measures

OBJECTIVE To assess and quantify the surgical learning curve of holmium laser enucleation of the prostate (HoLEP) of a single surgeon. METHODS A retrospective analysis of 253 consecutive cases performed by the same surgeon from 2006 to 2013 was conducted. Primary outcomes included enucleation ratio and morcellation efficiencies and complication rates. Three-month postoperative prostate-specific antigen values were used as secondary measures. Cases were divided into cohorts of 20 cases to assess changes in means analyzed through Analysis of Variance (ANOVA) tests. Scatter plots of cases with a best-fit line were drawn to analyze the learning curve. RESULTS The mean age of patients across the cases was 69.21 years with an average transrectal ultrasound prostate volume of 95.84 cc. Enucleation ratio efficiency was significantly different between cohorts (P = .02) plateau after 50-60 cases conducted. Similarly, a significant difference is shown for morcellation efficiency (P = .01) with stabilization in performance after 60 cases. Complication rates decreased through the caseload but did not show a statistical difference (P = .62) or plateauing on the graph. Finally, no difference between 3-month postoperative prostate-specific antigen values was seen (P = .083); however, a learning curve of 50 cases was observed graphically. CONCLUSION Within our single-surgeon cohort, we experienced a learning curve of 40-60 cases for the HoLEP procedure. Large variability in performance late into the caseload demonstrates the technical difficulty of HoLEP. Owing to this, adjuncts to training such as simulation-based training may be of use for the new surgeon to shorten the initial phase of learning.

Pathways to diagnosis for Black men and White men found to have prostate cancer: the PROCESS cohort study

Black men in England have three times the age-adjusted incidence of diagnosed prostate cancer as compared with their White counterparts. This population-based retrospective cohort study is the first UK-based investigation of whether access to diagnostic services underlies the association between race and prostate cancer. Prostate cancer was ascertained using multiple sources including hospital records. Race and factors that may influence prostate cancer diagnosis were assessed by questionnaire and hospital records review. We found that Black men were diagnosed an average of 5.1 years younger as compared with White men (P<0.001). Men of both races were comparable in their knowledge of prostate cancer, in the delays reported before presentation, and in their experience of co-morbidity and symptoms. Black men were more likely to be referred for diagnostic investigation by a hospital department (P=0.013), although general practitioners referred the large majority of men. Prostate-specific antigen levels were comparable at diagnosis, although Black men had higher levels when compared with same-age White men (P<0.001). In conclusion, we found no evidence of Black men having poorer access to diagnostic services. Differences in the run-up to diagnosis are modest and seem insufficient to explain the higher rate of prostate cancer diagnosis in Black men.

Successful Salvage Robotic-Assisted Radical Prostatectomy After External Beam Radiotherapy Failure

We describe the first case of salvage robotic-assisted radical prostatectomy for local recurrence after external beam radiotherapy. A 50-year-old man initially underwent combined external beam radiotherapy and hormonal treatment for Stage T2a prostate adenocarcinoma. The prostate-specific antigen level was 10.5 ng/mL, and the Gleason score was 3+3. Two years later, he developed biopsy-proven recurrent disease. He underwent salvage robotic-assisted radical prostatectomy. The patient was discharged on day 1 postoperatively. The histologic analysis revealed an organ-confined tumor. His prostate-specific antigen at 3 months was <0.03 ng/mL, and he was continent. Salvage robotic-assisted radical prostatectomy is a safe and technically feasible salvage treatment for prostate cancer for which primary radiotherapy has failed.