172 research outputs found

    Space Charge Limited Transport and Time of Flight Measurements in Tetracene Single Crystals: a Comparative Study

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    We report on a systematic study of electronic transport in tetracene single crystals by means of space charge limited current spectroscopy and time of flight measurements. Both II-VV and time of flight measurements show that the room-temperature effective hole-mobility reaches values close to μ≃1\mu \simeq 1 cm2^2/Vs and show that, within a range of temperatures, the mobility increases with decreasing temperature. The experimental results further allow the characterization of different aspects of the tetracene crystals. In particular, the effects of both deep and shallow traps are clearly visible and can be used to estimate their densities and characteristic energies. The results presented in this paper show that the combination of II-VV measurements and time of flight spectroscopy is very effective in characterizing several different aspects of electronic transport through organic crystals.Comment: Accepted by J. Appl. Phys.; tentatively scheduled for publication in the January 15, 2004 issue; minor revisions compared to previous cond-mat versio

    A Decision Analysis Evaluating Screening for Kidney Cancer Using Focused Renal Ultrasound

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    Background Screening for renal cell carcinoma (RCC) has been identified as a key research priority; however, no randomised control trials have been performed. Value of information analysis can determine whether further research on this topic is of value. Objective To determine (1) whether current evidence suggests that screening is potentially cost effective and, if so, (2) in which age/sex groups, (3) identify evidence gaps, and (4) estimate the value of further research to close those gaps. Design, setting, and participants A decision model was developed evaluating screening in asymptomatic individuals in the UK. A National Health Service perspective was adopted. Intervention A single focused renal ultrasound scan compared with standard of care (no screening). Outcome measurements and statistical analysis Expected lifetime costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio (ICER), discounted at 3.5% per annum. Results and limitations Given a prevalence of RCC of 0.34% (0.18–0.54%), screening 60-yr-old men resulted in an ICER of £18 092/QALY (€22 843/QALY). Given a prevalence of RCC of 0.16% (0.08–0.25%), screening 60-yr-old women resulted in an ICER of £37 327/QALY (€47 129/QALY). In the one-way sensitivity analysis, the ICER was <£30 000/QALY as long as the prevalence of RCC was ≥0.25% for men and ≥0.2% for women at age 60 yr. Given the willingness to pay a threshold of £30 000/QALY (€37 878/QALY), the population-expected values of perfect information were £194 million (€244 million) and £97 million (€123 million) for 60-yr-old men and women, respectively. The expected value of perfect parameter information suggests that the prevalence of RCC and stage shift associated with screening are key research priorities. Conclusions Current evidence suggests that one-off screening of 60-yr-old men is potentially cost effective and that further research into this topic would be of value to society. Patient summary Economic modelling suggests that screening 60-yr-old men for kidney cancer using ultrasound may be a good use of resources and that further research on this topic should be performed

    The Impact of Histological Subtype on the Incidence, Timing, and Patterns of Recurrence in Patients with Renal Cell Carcinoma After Surgery-Results from RECUR Consortium

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    Background: Current follow-up strategies for patients with renal cell carcinoma (RCC) after curative surgery rely mainly on risk models and the treatment delivered, regardless of the histological subtype. Objective: To determine the impact of RCC histological subtype on recurrence and to examine the incidence, pattern, and timing of recurrences to improve follow-up recommendations. Design, setting, and participants: This study included consecutive patients treated surgically with curative intention (ie, radical and partial nephrectomy) for non-metastatic RCC (cT1-4, M0) between January 2006 and December 2011 across 15 centres from 10 countries, as part of the euRopEan association of urology renal cell carcinoma guidelines panel Collaborative multicenter consortium for the studies of follow-Up and recurrence patterns in Radically treated renal cell carcinoma patients (RECUR) database project. Outcome measurements and statistical analysis: The impact of histological subtype (ie, clear cell RCC [ccRCC], papillary RCC [pRCC], and chromophobe RCC [chRCC]) on recurrence-free survival (RFS) was assessed via univariate and multivariate analyses, adjusting for potential interactions with important variables (stage, grade, risk score, etc.) Patterns of recurrence for all histological subtypes were compared according to recurrence site and risk criteria. Results and limitations: Of the 3331 patients, 62.2% underwent radical nephrectomy and 37.8% partial nephrectomy. A total of 2565 patients (77.0%) had ccRCC, 535 (16.1%) had pRCC, and 231 (6.9%) had chRCC. The median postoperative follow-up period was 61.7 (interquartile range: 47-83) mo. Patients with ccRCC had significantly poorer 5-yr RFS than patients with pRCC and chRCC (78% vs 86% vs 91%, p = 0.001). The most common sites of recurrence for ccRCC were the lung and bone. Intermediate-/high-risk pRCC patients had an increased rate of lymphatic recurrence, both mediastinal and retroperitoneal, while recurrence in chRCC was rare (8.2%), associated with higher stage and positive margins, and predominantly in the liver and bone. Limitations include the retrospective nature of the study. Conclusions: The main histological subtypes of RCC exhibit a distinct pattern and dynamics of recurrence. Results suggest that intermediate- to high-risk pRCC may benefit from cross-sectional abdominal imaging every 6 mo until 2 yr after surgery, while routine imaging might be abandoned for chRCC except for abdominal computed tomography in patients with advanced tumour stage or positive margins. Patient summary: In this analysis of a large database from 15 countries around Europe, we found that the main histological subtypes of renal cell carcinoma have a distinct pattern and dynamics of recurrence. Patients should be followed differently according to subtype and risk score. (C) 2020 Published by Elsevier B.V. on behalf of European Association of Urology.Peer reviewe

    Management of Sporadic Renal Angiomyolipomas: A Systematic Review of Available Evidence to Guide Recommendations from the European Association of Urology Renal Cell Carcinoma Guidelines Panel

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    CONTEXT: Little is known about the natural history of sporadic angiomyolipomas (AMLs); there is uncertainty regarding the indications of treatment and treatment options. OBJECTIVE: To evaluate the indications, effectiveness, harms, and follow-up of different management modalities for sporadic AML to provide guidance for clinical practice. EVIDENCE ACQUISITION: A systematic review of the literature was undertaken, incorporating Medline, Embase, and the Cochrane Library (from 1 January 1990 to 30 June 2017), in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. No restriction on study design was imposed. Patients with sporadic AML were included. The main interventions included active surveillance, surgery (nephron-sparing surgery and radical nephrectomy), selective arterial embolisation, and percutaneous or laparoscopic thermal ablations (radiofrequency, microwaves, or cryoablation). The outcomes included indications for active treatment, AML growth rate, AML recurrence rate, risk of bleeding, post-treatment renal function, adverse events of treatments, and modalities of follow-up. Risk of bias assessment was performed using standard Cochrane methods. EVIDENCE SYNTHESIS: Among 2704 articles identified, 43 were eligible for inclusion (zero randomised controlled trials, nine nonrandomised comparative retrospective studies, and 34 single-arm case series). Most studies were retrospective and uncontrolled, and had a moderate to high risk of bias. CONCLUSIONS: In active surveillance series, spontaneous bleeding was reported in 2% of patients and active treatment was undertaken in 5%. Active surveillance is the most chosen option in 48% of the cases, followed by surgery in 31% and selective arterial embolisation in 17% of the cases. Selective arterial embolisation appeared to reduce AML volume but required secondary treatment in 30% of the cases. Surgery (particularly nephron-sparing surgery) was the most effective treatment in terms of recurrence and need for secondary procedures. Thermal ablation was an infrequent option. The association between AML size and the risk of bleeding remained unclear; as such the traditional 4-cm cut-off should not per se trigger active treatment. In spite of the limitations and uncertainties relating to the evidence base, the findings may be used to guide and inform clinical practice, until more robust data emerge. PATIENT SUMMARY: Sporadic angiomyolipoma (AML) is a benign tumour of the kidney consisting of a mixture of blood vessels, fat, and muscle. Large tumours may have a risk of spontaneous bleeding. However, the size beyond which these tumours need to be treated remains unclear. Most small AMLs can be monitored without any active treatment. For those who need treatment, options include surgical removal of the tumour or stopping its blood supply (selective embolisation). Surgery has a lower recurrence rate and lower need for a repeat surgical procedure

    Costo-Efficacia di cabozantinib nel trattamento di seconda linea del tumore a cellule renali metastatico (mRCC) in Italia:

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    Introduction: Renal cell carcinoma (RCC) is the most common form of kidney cancer with >30% already metastatic at diagnosis. For patients who fail tyrosine kinase inhibitor (TKI) therapy, the Italian Medical Oncology Association recommends (level IA) nivolumab and cabozantinib. The aim of this study was to compare the cost-effectiveness of cabozantinib with nivolumab for treatment of adult patients with mRCC following prior TKI therapy in Italy. Methods: A partitioned survival (area under the curve) model was developed for the Italian medical environment. Cost-effectiveness was assessed from the Italian National Healthcare Service (SSN) perspective over a 30-year time horizon (annual discount: 3% rate). In the absence of head-to-head studies, clinical evidence was based on results of network meta-analysis. Health-state-related utilities were informed by EQ-5D data from the METEOR study. Resource use and costs were obtained from published sources. Results: Treatment with cabozantinib dominates nivolumab across a 30-years time horizon. In the reference case, treatment with cabozantinib results in an incremental 0.268 quality-adjusted life years (QALY) and an incremental 0.349 life years (LY) gained with a total saving, for the Italian SSN, of €5,605 compared to nivolumab over 30 years. Cabozantinib is associated with gains in quality adjusted life years versus nivolumab, in all analyses. Results were shown to be sensitive to drug prices variation and robust when altering other parameters. Discussion: Cabozantinib represents an efficient option in the management of mRCC after initial TKI-therapy in Italy. Drug prices impact final results, and this must be carefully considered, especially considering the confidential discounts and outcome/financial-based agreements currently in place in Italy

    Respiratory maneuvers in echocardiography: a review of clinical applications

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    During echocardiographic examination, respiration induces cyclic physiological changes of intracardiac haemodynamics, causing normal variations of the right and left ventricle Doppler inflows and outflows and physiological variation of extracardiac flows. The respiration related hemodynamic variation in intra and extracardiac flows may be utilized in the echocardiography laboratory to aid diagnosis in different pathological states. Nevertheless, physiologic respiratory phases can cause excessive translational motion of cardiac structures, lowering 2D image quality and interfering with optimal Doppler interrogation of flows or tissue motion
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