The impact of cardiopulmonary exercise testing (CPET) and Charlson comorbidity index (CCI) in a large contemporary cohort of patients undergoing robot-assisted radical cystectomy and intracorporeal urinary diversion (RARC-ICUD).

Objective: The aim of this study was to investigate whether pre-operative comorbidity status measured by the Charlson comorbidity index (CCI) or cardiopulmonary exercise testing (CPET) is associated with postoperative complications and length of stay (LOS) in patients undergoing robot-assisted radical cystectomy and intracorporeal urinary diversion (RARC-ICUD). Patients and methods: We conducted a retrospective study of a prospectively maintained database of 428 consecutive patients who underwent RARC-ICUD at a tertiary referral centre between 2011 and 2019. CCI was correlated with peri-operative outcomes including postoperative LOS, Clavien-Dindo (CD) complications and survival. A planned subgroup analysis was performed to evaluate the relationship between pre-operative CPET, and the same outcomes utilising the threshold of anaerobic threshold (AT) ≥ 11/ <11 ml/kg/min were analysed. Results: Of the total cohort, 350 patients undergoing RARC-ICUD with complete data were included in the final analysis. A CCI score ≥5 was associated with a higher rate of CD III-V complications at 30-day incidence rate ratio (IRR) = 3.033, (p = 0.02) and at 90-day IRR 2.495, (p = 0.04) postsurgery. LOS was not associated with CCI; the strongest association with LOS was a CD complication of any grading. CCI did not predict readmission or mortality rates after surgery. Subanalyses of patients who underwent pre-operative CPET found that CPET <11 ml/kg/min did not predict for LOS, CD complications or death within 1 year of surgery. Conclusions: CCI score is a simple, reliable and cost-effective way of identifying patients at increased risk of complication after RARC-ICUD. Surgeons performing radical cystectomy should consider utilising CCI to augment pre-operative patient counselling prior to RARC-ICUD.

Sonography in male infertility: a useful yet underutilized diagnostic tool.

PURPOSE: To assess the utility of comprehensive sonographic examination including scrotal sonography, Testicular Doppler and Transrectal Ultrasound (TRUS) to evaluate the male reproductive system and differentiate between obstructive (OG) and non-obstructive (NOG) causes of azoospermia. METHODS: 30 infertile men with azoospermia and 30 control subjects with normospermia underwent sonographic evaluation. FNAC/biopsy findings were used for assigning a final diagnosis of obstructive or non-obstructive azoospermia. Qualitative and quantitative imaging parameters were retrospectively compared between the groups using Chi-square/Fisher's exact test and unpaired t-test, respectively. P < 0.05 was considered significant. RESULTS: Ectasia of rete testis/epididymal tubules, altered epididymal echogenicity, dilated terminal vas deferens were significantly more common in OG while inhomogeneous testicular echo-texture and reduced testicular vascularity were more common in NOG (P < 0.05). Testicular volume and epididymal head size were significantly higher in OG than in NOG and controls (18.2 ml/10 mm Vs 8.2 ml/7.2 mm and 13.4 ml/8.8 mm respectively; P < 0.05); while Resistive Index (RI) of intra-testicular vessels was higher in NOG as compared to OG and controls (0.65 vs 0.54 and 0.52 respectively; P < 0.05). On ROC curve analysis, cut-off values of testicular volume (AUC: 0.939; P < 0.001), epididymal head size (AUC: 0.772; P = 0.001) and testicular RI (AUC: 0.761; P = 0.001) to differentiate between the groups were 12.1 ml (sensitivity-94.4%; specificity-83.3%), 9 mm (sensitivity-66.7%; specificity-71%) and 0.62 (sensitivity-62%; specificity-100%) respectively. CONCLUSION: Comprehensive sonographic evaluation can be used to differentiate obstructive from non-obstructive infertility and should be routinely incorporated in the diagnostic workup of infertile men with azoospermia.

Unearthing real-time 3D ant tunneling mechanics.

Granular excavation is the removal of solid, discrete particles from a structure composed of these objects. Efficiently predicting the stability of an excavation during particle removal is an unsolved and highly nonlinear problem, as the movement of each grain is coupled to its neighbors. Despite this, insects such as ants have evolved to be astonishingly proficient excavators, successfully removing grains such that their tunnels are stable. Currently, it is unclear how ants use their limited information about the environment to construct lasting tunnels. We attempt to unearth the ants' tunneling algorithm by taking three-dimensional (3D) X-ray computed tomographic imaging (XRCT), in real time, of Pogonomyrmex ant tunnel construction. By capturing the location and shape of each grain in the domain, we characterize the relationship between particle properties and ant decision-making within an accurate, virtual recreation of the experiment. We discover that intergranular forces decrease significantly around ant tunnels due to arches forming within the soil. Due to this force relaxation, any grain the ants pick from the tunnel surface will likely be under low stress. Thus, ants avoid removing grains compressed under high forces without needing to be aware of the force network in the surrounding material. Even more, such arches shield tunnels from high forces, providing tunnel robustness. Finally, we observe that ants tend to dig piecewise linearly downward. These results are a step toward understanding granular tunnel stability in heterogeneous 3D systems. We expect that such findings may be leveraged for robotic excavation.

Major Urological Cancer Surgery for Patients is Safe and Surgical Training Should Be Encouraged During the COVID-19 Pandemic: A Multicentre Analysis of 30-day Outcomes.

COVID-19 has resulted in the deferral of major surgery for genitourinary (GU) cancers with the exception of cancers with a high risk of progression. We report outcomes for major GU cancer operations, namely radical prostatectomy (RP), radical cystectomy (RC), radical nephrectomy (RN), partial nephrectomy (PN), and nephroureterectomy performed at 13 major GU cancer centres across the UK between March 1 and May 5, 2020. A total of 598 such operations were performed. Four patients (0.7%) developed COVID-19 postoperatively. There was no COVID-19-related mortality at 30 d. A minimally invasive approach was used in 499 cases (83.4%). A total of 228 cases (38.1%) were described as training procedures. Training case status was not associated with a higher American Society of Anesthesiologists (ASA) score (p = 0.194) or hospital length of stay (LOS; p > 0.05 for all operation types). The risk of contracting COVID-19 was not associated with longer hospital LOS (p = 0.146), training case status (p = 0.588), higher ASA score (p = 0.295), or type of hospital site (p = 0.303). Our results suggest that major surgery for urological cancers remains safe and training should be encouraged during the ongoing COVID-19 pandemic provided appropriate countermeasures are taken. These real-life data are important for policy-makers and clinicians when counselling patients during the current pandemic. PATIENT SUMMARY: We collected outcome data for major operations for prostate, bladder, and kidney cancers during the COVID-19 pandemic. These surgeries remain safe and training should be encouraged during the ongoing pandemic provided appropriate countermeasures are taken. Our real-life results are important for policy-makers and clinicians when counselling patients during the COVID-19 pandemic.

Benefits and Risks of Primary Treatments for High-risk Localized and Locally Advanced Prostate Cancer: An International Multidisciplinary Systematic Review.

CONTEXT: The optimal treatment for men with high-risk localized or locally advanced prostate cancer (PCa) remains unknown. OBJECTIVE: To perform a systematic review of the existing literature on the effectiveness of the different primary treatment modalities for high-risk localized and locally advanced PCa. The primary oncological outcome is the development of distant metastases at ≥5 yr of follow-up. Secondary oncological outcomes are PCa-specific mortality, overall mortality, biochemical recurrence, and need for salvage treatment with ≥5 yr of follow-up. Nononcological outcomes are quality of life (QoL), functional outcomes, and treatment-related side effects reported. EVIDENCE ACQUISITION: Medline, Medline In-Process, Embase, and the Cochrane Central Register of Randomized Controlled Trials were searched. All comparative (randomized and nonrandomized) studies published between January 2000 and May 2019 with at least 50 participants in each arm were included. Studies reporting on high-risk localized PCa (International Society of Urologic Pathologists [ISUP] grade 4-5 [Gleason score {GS} 8-10] or prostate-specific antigen [PSA] >20 ng/ml or ≥ cT2c) and/or locally advanced PCa (any PSA, cT3-4 or cN+, any ISUP grade/GS) or where subanalyses were performed on either group were included. The following primary local treatments were mandated: radical prostatectomy (RP), external beam radiotherapy (EBRT) (≥64 Gy), brachytherapy (BT), or multimodality treatment combining any of the local treatments above (±any systemic treatment). Risk of bias (RoB) and confounding factors were assessed for each study. A narrative synthesis was performed. EVIDENCE SYNTHESIS: Overall, 90 studies met the inclusion criteria. RoB and confounding factors revealed high RoB for selection, performance, and detection bias, and low RoB for correction of initial PSA and biopsy GS. When comparing RP with EBRT, retrospective series suggested an advantage for RP, although with a low level of evidence. Both RT and RP should be seen as part of a multimodal treatment plan with possible addition of (postoperative) RT and/or androgen deprivation therapy (ADT), respectively. High levels of evidence exist for EBRT treatment, with several randomized clinical trials showing superior outcome for adding long-term ADT or BT to EBRT. No clear cutoff can be proposed for RT dose, but higher RT doses by means of dose escalation schemes result in an improved biochemical control. Twenty studies reported data on QoL, with RP resulting mainly in genitourinary toxicity and sexual dysfunction, and EBRT in bowel problems. CONCLUSIONS: Based on the results of this systematic review, both RP as part of multimodal treatment and EBRT + long-term ADT can be recommended as primary treatment in high-risk and locally advanced PCa. For high-risk PCa, EBRT + BT can also be offered despite more grade 3 toxicity. Interestingly, for selected patients, for example, those with higher comorbidity, a shorter duration of ADT might be an option. For locally advanced PCa, EBRT + BT shows promising result but still needs further validation. In this setting, it is important that patients are aware that the offered therapy will most likely be in the context a multimodality treatment plan. In particular, if radiation is used, the combination of local with systemic treatment provides the best outcome, provided the patient is fit enough to receive both. Until the results of the SPCG15 trial are known, the optimal local treatment remains a matter of debate. Patients should at all times be fully informed about all available options, and the likelihood of a multimodal approach including the potential side effects of both local and systemic treatment. PATIENT SUMMARY: We reviewed the literature to see whether the evidence from clinical studies would tell us the best way of curing men with aggressive prostate cancer that had not spread to other parts of the body such as lymph glands or bones. Based on the results of this systematic review, there is good evidence that both surgery and radiation therapy are good treatment options, in terms of prolonging life and preserving quality of life, provided they are combined with other treatments. In the case of surgery this means including radiotherapy (RT), and in the case of RT this means either hormonal therapy or combined RT and brachytherapy.

Edge States and Topological Pumping in Spatially Modulated Elastic Lattices.

Spatial stiffness modulations defined by the sampling of a two-dimensional surface provide one-dimensional elastic lattices with topological properties that are usually attributed to two-dimensional crystals. The cyclic modulation of the stiffness defines a family of lattices whose Bloch eigenmodes accumulate a phase quantified by integer valued Chern numbers. Nontrivial gaps are spanned by edge modes in finite lattices whose location is determined by the phase of the stiffness modulation. These observations drive the implementation of a topological pump in the form of an array of continuous elastic beams coupled through a distributed stiffness. Adiabatic stiffness modulations along the beams' length lead to the transition of localized states from one boundary, to the bulk and, finally, to the opposite boundary. The first demonstration of topological pumping in a continuous elastic system opens new possibilities for its implementation on elastic substrates supporting surface acoustic waves, or to structural components designed to steer waves or isolate vibrations.

Benefits of Empiric Nutritional and Medical Therapy for Semen Parameters and Pregnancy and Live Birth Rates in Couples with Idiopathic Infertility: A Systematic Review and Meta-analysis.

CONTEXT: Empiric use of medical and nutritional supplements to improve semen parameters and pregnancy rates in couples with idiopathic infertility has reached global proportions, although the evidence base for their use in this setting is controversial. OBJECTIVE: We systematically reviewed evidence comparing the benefits of nutritional and medical therapy on pregnancy rates and semen parameters in men with idiopathic infertility. EVIDENCE ACQUISITION: A literature search was performed using MEDLINE, Embase, LILACS, and the Cochrane Library (searched from January 1, 1990 to September 19, 2017). using the methods detailed in the Cochrane Handbook. Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to assess the certainty of evidence. EVIDENCE SYNTHESIS: The literature search identified 5663 citations, and after screening of abstracts and full texts, 61 studies (59 randomised controlled trials and two nonrandomised comparative studies) were included. Pooled results demonstrated that pentoxyfylline, coenzyme Q10, L-carnitine, follicle-stimulating hormone, tamoxifen, and kallikrein all resulted in improvements in semen parameters. Individual studies identified several other medical and nutritional therapies that improved semen parameters, but data were limited to individual studies with inherent methodological flaws. There were limited data available on live birth and pregnancy rates for all interventions. The GRADE certainty of evidence for all outcomes was very low mainly owing to methodological flaws and inconsistencies in study design. Some outcomes were also downgraded owing to imprecision of results. CONCLUSIONS: There is some evidence that empiric medical and nutritional supplements may improve semen parameters. There is very limited evidence that empiric therapy leads to better live birth rates, spontaneous pregnancy, or pregnancy following assisted-reproductive techniques. However, the findings should be interpreted with caution as there were some methodological flaws, as a number of studies were judged to be either at high or unclear risk of bias for many domains. PATIENT SUMMARY: This review identified several medical and nutritional treatments, such as pentoxyfylline, coenzyme Q10, L-carnitine, follicle-stimulating hormone, tamoxifen, and kallikrein, that appear to improve semen parameters. However, there are limited data suggesting improvements in pregnancy and live birth rates. The lack of evidence can be attributed to methodological flaws in studies and the low number of pregnancies reported.

Expanding the indications of robotic surgery in urology: A systematic review of the literature.

OBJECTIVES: To evaluate the recent developments in robotic urological surgery, as the introduction of robotic technology has overcome many of the difficulties of pure laparoscopic surgery enabling surgeons to perform complex minimally invasive procedures with a shorter learning curve. Robot-assisted surgery (RAS) is now offered as the standard for various surgical procedures across multiple specialities. METHODS: A systematic search of MEDLINE, PubMed and EMBASE databases was performed to identify studies evaluating robot-assisted simple prostatectomy, salvage radical prostatectomy, surgery for urolithiasis, distal ureteric reconstruction, retroperitoneal lymph node dissection, augmentation ileocystoplasty, and artificial urinary sphincter insertion. Article titles, abstracts, and full text manuscripts were screened to identify relevant studies, which then underwent data extraction and analysis. RESULTS: In all, 72 studies evaluating the above techniques were identified. Almost all studies were retrospective single-arm case series. RAS appears to be associated with reduced morbidity, less blood loss, reduced length of stay, and comparable clinical outcomes in comparison to the corresponding open procedures, whilst having a shorter operative duration and learning curve compared to the equivalent laparoscopic techniques. CONCLUSION: Emerging data demonstrate that the breadth and complexity of urological procedures performed using the da Vinci® platform (Intuitive Surgical Inc., Sunnyvale, CA, USA) is continually expanding. There is a gaining consensus that RAS is producing promising surgical results in a wide range of procedures. A major limitation of the current literature is the sparsity of comparative trials evaluating these procedures.

A study of deformation localization in nonlinear elastic square lattices under compression.

The paper investigates localized deformation patterns resulting from the onset of instabilities in lattice structures. The study is motivated by previous observations on discrete hexagonal lattices, where a variety of localized deformations were found depending on loading configuration, lattice parameters and boundary conditions. These studies are conducted on other lattice structures, with the objective of identifying and investigating minimal models that exhibit localization, hysteresis and path-dependent behaviour. To this end, we first consider a two-dimensional square lattice consisting of point masses connected by in-plane axial springs and vertical ground springs, which may be considered as a discrete description of an elastic membrane supported by an elastic substrate. Results illustrate that, depending on the relative values of the spring constants, the lattice exhibits in-plane or out-of-plane instabilities leading to localized deformations. This model is further simplified by considering the one-dimensional case of a spring-mass chain sitting on an elastic foundation. A bifurcation analysis of this lattice identifies the stable and unstable branches and sheds light on the mechanism of transition from affine deformation to global or diffuse deformation to localized deformation. Finally, the lattice is further reduced to a minimal four-mass model, which exhibits a deformation qualitatively similar to that in the central part of a longer chain. In contrast to the widespread assumption that localization is induced by defects or imperfections in a structure, this work illustrates that such phenomena can arise in perfect lattices as a consequence of the mode shapes at the bifurcation points.This article is part of the theme issue 'Nonlinear energy transfer in dynamical and acoustical systems'.

Amplitude-dependent topological edge states in nonlinear phononic lattices.

This work investigates the effect of nonlinearities on topologically protected edge states in one- and two-dimensional phononic lattices. We first show that localized modes arise at the interface between two spring-mass chains that are inverted copies of each other. Explicit expressions derived for the frequencies of the localized modes guide the study of the effect of cubic nonlinearities on the resonant characteristics of the interface, which are shown to be described by a Duffing-like equation. Nonlinearities produce amplitude-dependent frequency shifts, which in the case of a softening nonlinearity cause the localized mode to migrate to the bulk spectrum. The case of a hexagonal lattice implementing a phononic analog of a crystal exhibiting the quantum spin Hall effect is also investigated in the presence of weakly nonlinear cubic springs. An asymptotic analysis provides estimates of the amplitude dependence of the localized modes, while numerical simulations illustrate how the lattice response transitions from bulk-to-edge mode-dominated by varying the excitation amplitude. In contrast with the interface mode of the first example studies, this occurs both for hardening and softening springs. The results of this study provide a theoretical framework for the investigation of nonlinear effects that induce and control topologically protected wave modes through nonlinear interactions and amplitude tuning.

Sonography in male infertility: a look beyond the obvious.

Infertility affects 15-20% of the reproductive age range population; the male factor accounts for up to 40-60% of these. With female factor infertility catching most of the limelight in research, diagnosis and treatment, the other half of the problem has not been duly addressed. Imaging has an important role to play in the evaluation of male infertility, especially to identify correctible (obstructive) causes. We review the scrotal, trans-rectal sonographic and Doppler findings in infertile men to aid in the accurate diagnosis and proper management of such patients.

A Single Center Evaluation of the Diagnostic Accuracy of Multiparametric Magnetic Resonance Imaging against Transperineal Prostate Mapping Biopsy: An Analysis of Men with Benign Histology and Insignificant Cancer following Transrectal Ultrasound Biopsy.

PURPOSE: In this study we evaluated the diagnostic performance of transrectal ultrasound guided biopsy and multiparametric magnetic resonance imaging to detect prostate cancer against transperineal prostate mapping biopsy as the reference test. MATERIALS AND METHODS: Transrectal ultrasound guided biopsy, multiparametric magnetic resonance imaging and transperineal prostate mapping biopsy were performed in 426 patients between April 2012 and January 2016. Patients initially underwent systematic 12 core transrectal ultrasound guided biopsy followed 3 months later by 1.5 Tesla, high resolution T2, diffusion-weighted, dynamic contrast enhanced multiparametric magnetic resonance imaging. Two specialist uroradiologists blinded to the results of transperineal prostate mapping biopsy allocated a PI-RADS™ (Prostate Imaging-Reporting and Data System) score to each multiparametric magnetic resonance imaging study. Transperineal prostate mapping biopsy with 5 mm interval sampling, which was performed within 6 months of multiparametric magnetic resonance imaging, served as the reference test. RESULTS: Transrectal ultrasound guided biopsy identified 247 of 426 patients with prostate cancer and 179 of 426 with benign histology. Transperineal prostate mapping biopsy detected prostate cancer in 321 of 426 patients. On transperineal prostate mapping biopsy 94 of 179 patients with benign transrectal ultrasound guided biopsy had prostate cancer and 95 of 247 with prostate cancer on transrectal ultrasound guided biopsy were identified with cancer of higher grade. Using a multiparametric magnetic resonance imaging PI-RADS score of 3 or greater to detect significant prostate cancer, defined as any core containing Gleason 4 + 3 or greater prostate cancer on transperineal prostate mapping biopsy, the ROC AUC was 0.754 (95% CI 0.677-0.819) with 87.0% sensitivity (95% CI 77.3-97.0), 55.3% specificity (95% CI 50.2-60.4) and 97.1% negative predictive value (95% CI 94.8-99.4). CONCLUSIONS: Multiparametric magnetic resonance imaging is a more accurate diagnostic test than transrectal ultrasound guided biopsy. However, a significant proportion of ISUP (International Society of Urological Pathology) Grade Group 2 prostate cancer remained undetected following multiparametric magnetic resonance imaging. Although multiparametric magnetic resonance imaging could avoid unnecessary biopsy in many patients with ISUP Grade Group 3 or greater prostate cancer, at less stringent definitions of significant cancer a substantial proportion of prostate cancer would remain undetected after multiparametric magnetic resonance imaging.

Utility of early transperineal template-guided prostate biopsy for risk stratification in men undergoing active surveillance for prostate cancer.

OBJECTIVE: To assess the accuracy and utility of routine multiparametric magnetic resonance imaging (mpMRI) and transperineal template-guided prostate biopsy (TPB) after enrolment in active surveillance (AS). PATIENTS AND METHODS: From April 2012 to December 2016 consecutive men from our single institution, diagnosed with low- or intermediate-risk prostate cancer on transrectal ultrasonography-guided biopsy, were offered further staging with early mpMRI and TPB within 12 months of diagnosis. Data were collected prospectively. Eligibility criteria comprised: age ≤77 years; Gleason score ≤3 + 4; clinical stage T1-T2; PSA ≤15 ng/mL; and <50% positive biopsy cores. RESULTS: A total of 208 men were enrolled, including 196 with Gleason score 3 + 3 and 12 with Gleason score 3 + 4 disease. The median (range) number of TPB cores was 50 (17-161), with a mean TPB core density of 1.2 cores/cm3 prostate volume. A total of 83 men (39.9%) underwent histopathological upgrading after TPB, including 76 men (38.8%) with Gleason score 3 + 3 disease and seven men (58.3%) with Gleason score 3 + 4 disease. Of these, 26 (31.3%) were found to harbour primary pattern Gleason grade ≥4 disease. In all, 24 (28.9%) upgraded cases had Prostate Imaging Reporting and Data System (PI-RADS) score 1 or 2 lesions on mpMRI, including five men with Gleason score ≥4 + 3 disease. Of these, 14 (58.3%) had a prostate-specific antigen (PSA) density of ≥0.15, including four out of the five men with Gleason ≥4 + 3 disease. Overall there was a change in prostate cancer management in 77 men (37.0%) after TPB. CONCLUSIONS: Early TPB during AS is associated with significant upgrading and a change in treatment plan in over a third of men. If TPB was omitted in men with a PI-RADS score <3 and a PSA density <0.15, 12% of those harbouring more significant disease would have been misclassified.

Immunocytochemical detection of ERG expression in exfoliated urinary cells identifies with high specificity patients with prostate cancer.

OBJECTIVES: To evaluate the immunocytochemical detection of ERG protein in exfoliated cells as a means of identifying patients with prostate cancer (PCa) before prostate biopsy. MATERIALS AND METHODS: Urine samples (30 mL) were collected after digital rectal examination (DRE) from 159 patients with an elevated age-specific prostate-specific antigen (PSA) and/or an abnormal DRE who underwent prostate biopsy. In all cases, exfoliated urinary cells from half of the urine sample underwent immunocytochemical assessment for ERG protein expression. Exfoliated cells in the remaining half underwent assessment of TMPRSS2:ERG status using either nested reverse-transcriptase (RT)-PCR (151 cases) or fluorescence in situ hybridization (FISH; eight cases). Corresponding tissue samples were evaluated using FISH to determine chromosomal gene fusion tissue status and immunohistochemistry (IHC) to determine ERG protein expression. Results were correlated with clinicopathological variables. RESULTS: The sensitivity and specificity of urinary ERG immunocytochemistry (ICC) for PCa were 22.7 and 100%, respectively. ERG ICC results correlated with advanced tumour grade, stage and higher serum PSA. In comparison, urine TMPRSS2:ERG transcript analysis had 27% sensitivity and 98% specificity for PCa detection. On tissue IHC, ERG staining was highly specific for PCa. In all, 52% of cancers harboured foci of ERG staining; however, only 46% of cancers that were found to have ERG overexpression were positive on urine ICC. The ERG ICC results showed strong concordance with urinary RT-PCR and FISH, and tissue IHC and FISH. CONCLUSION: This is the first study to show that cytological gene fusion detection using ICC is feasible and identifies patients with adverse disease markers. ERG ICC was highly specific, but this technique was less sensitive than RT-PCR.

Wave tailoring by precompression in confined granular systems.

We present a granular system whose response under an impact load can be varied from rapidly decaying to almost constant amplitude waves by an external regulator. The system consists of a granular chain of larger spheres surrounded by small spheres, confined in a hollow cylindrical tube and supporting wave propagation along the axis of the cylinder. We demonstrate using numerical simulations that the response can be controlled by applying radial precompression. These observations are then complemented by an asymptotic analysis, which shows that the decay in the leading wave is due to energy leakage to the oscillating small beads in the tail of the wave. This system has potential applications in systems requiring tuning of elastic waves.

Characterization of wave propagation in elastic and elastoplastic granular chains.

For short duration impulse loadings, elastic granular chains are known to support solitary waves, while elastoplastic chains have recently been shown to exhibit two force decay regimes [ Pal, Awasthi and Geubelle Granular Matter 15 747 (2013)]. In this work, the dynamics of monodisperse elastic and elastoplastic granular chains under a wide range of loading conditions is studied, and two distinct response regimes are identified in each of them. In elastic chains, a short loading duration leads to a single solitary wave propagating down the chain, while a long loading duration leads to the formation of a train of solitary waves. A simple model is developed to predict the peak force and wave velocity for any loading duration and amplitude. In elastoplastic chains, wave trains form even for short loading times due to a mechanism distinct from that in elastic chains. A model based on energy balance predicts the decay rate and transition point between the two decay regimes. For long loading durations, loading and unloading waves propagate along the chain, and a model is developed to predict the contact force and particle velocity.

Transperineal template prostate biopsies in men with raised PSA despite two previous sets of negative TRUS-guided prostate biopsies.

BACKGROUND: The possibility of prostate cancer as a cause for steadily rising PSA despite previously negative transrectal ultrasound (TRUS)-guided prostate biopsies is a major concern. An initial negative TRUS-guided prostate biopsy does not necessarily exclude the presence of clinically significant prostate cancer. We determined the role of transperineal template prostate biopsy (TPTPB) in prostate cancer detection in men with raised PSA despite two previous sets of negative TRUS biopsies. METHODS: Between January 2008 and August 2012, a total of 122 men's records were reviewed after having 36-core TPTPB following two previous sets of negative TRUS biopsies despite raised PSA. A retrospective record of PSA levels, clinicopathological parameters and histological outcomes was made. RESULTS: Mean age was 63 years (range 49-77), and mean PSA was 18.0 (range 2.0-119.0). A total of 71/122 (58 %) men were diagnosed with prostate cancer on TPTPB. Of these, 28 (39 %), 34 (48 %), 5 (7 %), and 4 (6 %) had Gleason score 6, 7 (3 + 4), 7 (4 + 3), and 9 (4 + 5), respectively. The mean number of positive cores was 7 (range 1-22). Of these, only 15 (21 %) had ≤2 cores positive and Gleason score of 6. Of the 51 (42 %) men with a negative histology on TPTPB, 11 (22 %), 10 (19 %), and 30 (59 %) had atypical small acinar proliferation, high-grade prostatic intraepithelial neoplasia, or benign pathology. CONCLUSION: TPTPB is associated with a high rate of clinically significant prostate cancer diagnosis (58 %) in men with raised PSA despite two previous sets of negative TRUS biopsies.

Defining prostate cancer risk before prostate biopsy.

Prostate cancer is the most commonly diagnosed cancer in men. At present, patients are selected for prostate biopsy on the basis of age, serum prostate specific antigen (PSA), and prostatic digital rectal examination (DRE) findings. However, due to limitations in the use of PSA and DRE, many patients undergo unnecessary prostate biopsy. A further problem arises as many patients are diagnosed and treated for indolent disease. This review of the literature highlights the strengths and weaknesses of existing methods of prebiopsy risk stratification and evaluates promising serum, urine, and radiologic prostate cancer biomarkers, which may improve risk stratification for prostate biopsy in the future.

Risk of erectile dysfunction and retrograde ejaculation associated with thulium laser vaporesection of the prostate for bladder outflow obstruction: a retrospective study.

OBJECTIVE: The aim of this study was to determine the incidence of erectile dysfunction and retrograde ejaculation following thulium:yttrium-aluminium-garnet (Tm:YAG) laser prostate vaporesection (ThuVaRP). PATIENTS AND METHODS: Between January 2009 and June 2010, 113 consecutive patients underwent ThuVaRP for bladder outflow obstruction. Of these, 54 (48%) were included in the study as they were able to maintain an erection for sexual intercourse prior to undergoing ThuVaRP. All patients had benign pathology and had not undergone previous bladder neck surgery. The incidence of erectile dysfunction and retrograde ejaculation was reported at a mean follow-up period of 12 months post-operatively. RESULTS: The mean patient age was 71 years (range 46-90). The mean follow-up period was 12 months (range 4-21). 11 (20%) patients experienced worsening erectile function with 3 (6%) noticing an improvement. A total of 30 patients (56%) experienced some degree of retrograde ejaculation. 4 patients (7%) noticed an improvement in their ejaculation. Retrograde ejaculation was more common in patients with an indwelling catheter in situ for refractory urinary retention (43 vs. 17%, p = 0.04) and in diabetic patients (27 vs. 4%, p = 0.03). There was an increased trend of erectile dysfunction in men aged ≥70 years, with hypertension and with hypercholesterolaemia, but this was not significant. CONCLUSION: Our retrospective study has demonstrated that the overall risk of erectile dysfunction and retrograde ejaculation associated with ThuVaRP is 20 and 56%, respectively.

Intermediate-term efficacy of Tm:YAG laser prostate vaporesection for bladder outlet obstruction: initial experience from a UK teaching hospital.

OBJECTIVES: To assess the safety and clinical efficacy of Tm:YAG laser vaporesection of the prostate (ThuVaRP) at intermediate-term follow-up. PATIENTS AND METHODS: We identified the first 60 consecutive patients who underwent ThuVaRP at our institute. Operative outcomes assessed were resection time, resection weight, drop in haemoglobin, transfusion rate, catheter time and complication rate. The International Prostate Symptom Score (IPSS) was documented at a mean follow-up period of 19 months postoperatively. RESULTS: 45/60 patients underwent treatment due to lower urinary tract symptoms secondary to benign prostatic obstruction, 11/60 patients had a long-term catheter in situ for refractory urinary retention secondary to benign prostatic obstruction, and 4/60 patients had bladder outflow obstruction secondary to adenocarcinoma of the prostate. 1/60 patients developed urosepsis, 1/60 patients developed a urinary tract infection and 1/60 patients required 3-way catheterization and irrigation due to haematuria. No patients required a blood transfusion. The mean IPSS at a mean follow-up interval of 19 months (range 15-28 months) was 5.1 (range 1-23). Postoperative maximum flow rate improved from 7.9 to 17.1 ml/s, and post-micturition residual volume decreased from 254 to 86 ml. CONCLUSION: ThuVaRP is safe and appears to have durable efficacy at intermediate follow-up.