Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

To determine whether the number and location of positive surgical margins (PSMs) in radical prostatectomy (RP) surgical specimens affect biochemical recurrence (BCR) rates.', 'The locations of PSMs were recorded for 1308 consecutive men who underwent RP between October 2000 and December 2006. BCR was defined as three consecutive prostate-specific antigen (PSA) level rises with the peak level >or=0.15 ng/mL. Multivariate regression analyses were used to identify preoperative predictors of PSMs and BCR. The estimated 5-year risk of BCR was calculated using the Kaplan-Meier method.', 'In all, 128 (9.8%) men had one or more PSMs. The mean body mass index, mean preoperative serum PSA level, the distributions of clinical stage and biopsy Gleason scores, and the presence or absence of biopsy perineural invasion were significantly different between men with or with no PSMs. In multivariate analysis, baseline serum PSA level, Gleason score and perineural invasion were independent preoperative predictors of PSMs. The 5-year actuarial BCR rates were dependent on the site of the PSM (P = 0.035) and not the number of PSMs (P = 0.18). The rank order of estimated 5-year BCR rates according to the site of PSMs were base > anterior > posterolateral > apex approximately posterior.
Does site of positive surgical margins influence biochemical recurrence after radical prostatectomy?

Pigs are frequently used as animal models in experimental medicine. To identify processes of vascular development or regression, vascular elements must be recognised and quantified in a three-dimensional (3D) arrangement. Vascular corrosion casts enable the creation of 3D replicas of vascular trees. The aim of our study was to identify suitable casting media and optimise the protocol for porcine liver vascular corrosion casting.', 'Mercox II®️ (Ladd Research, Williston, Vermont, USA) and Biodur E20®️ Plus (Biodur Products, Heidelberg, Germany) were tested in 4 porcine livers. The resins (volume approximately 700 mL) were injected via the portal vein. Corrosion casts were examined by macro-computed tomography, micro-computed tomography and scanning electron microscopy.', 'For hepatectomies, the operating protocol was optimised to avoid gas or blood clot embolisation. We present a protocol for porcine liver vascular bed casting based on corrosion specimens prepared using Biodur E20®️ epoxy resin.
Does porcine liver vascular bed in Biodur E20 corrosion cast?

There is increasing interest in educational methods that are loosely aggregated under the title of problem-based learning (PBL), but it remains unclear whether PBL is as successful as its conventional predecessor in transmitting factual information.', "The authors designed and implemented a PBL curriculum for a third-year surgical clerkship, then prospectively compared that technique with the conventional format. Each student's subject-related knowledge was assessed with a specifically tailored 195-question written exam and correlated with National Board of Medical Examiners shelf exams. Student and faculty responses to the technique were also sought and tabulated.", 'Student and faculty responses to PBL were uniformly positive. We were unable, however, to demonstrate effects on our evaluation instruments. Neither individual student performance nor grouped scores differed based on the mode of presentation.
Is problem orientation a new approach to surgical education?