This study demonstrated an inverse correlation between deposition of encrusting bodies and the local WSS in a stented ureter model. Critical regions with low WSS and susceptible to encrustation were identified, including "inactive" side holes (i.e., with minimal or absent flow exchange between stent and ureter) and the cavity formed by a ureteral occlusion. Findings from this study can open new avenues for improving the stent's design through fluid dynamic optimization.
Ureteric stents are clinically deployed to retain ureteral patency in the presence of an obstruction of the ureter lumen. Despite the fact that multiple stent designs have been researched in recent years, encrustation and biofilm-associated infections remain significant complications of ureteral stenting, potentially leading to the functional failure of the stent. It has been suggested that “inactive” side-holes of stents may act as anchoring sites for encrusting crystals, as they are associated with low wall shear stress (WSS) levels. Obstruction of side-holes due to encrustation is particularly detrimental to the function of the stent, since holes provide a path for urine to by-pass the occlusion. Therefore, there is an unmet need to develop novel stents to reduce deposition of encrusting particles at side-holes. In this study, we employed a stent-on-chip microfluidic model of the stented and occluded ureter to investigate the effect of stent architecture on WSS distribution and encrustation over its surface. Variations in the stent geometry encompassed (i) the wall thickness and (ii) the shape of side-holes. Stent thickness was varied in the range 0.3-0.7 mm, while streamlined side-holes of triangular shape were evaluated (with a vertex angle in the range 45°-120°). Reducing the thickness of the stent increased WSS and thus reduced the encrustation rate at side-holes. A further improvement in performance was achieved by using side-holes with a triangular shape; notably, a 45° vertex angle showed superior performance compared to other angles investigated, resulting in a significant increase in WSS within “inactive” side-holes. In conclusion, combining the optimal stent thickness (0.3 mm) and hole vertex angle (45°) resulted in a ∼90% reduction in encrustation rate within side-holes, compared to a standard design. If translated to a full-scale ureteric stent, this optimised architecture has the potential for significantly increasing the stent lifetime while reducing clinical complications.
OBJECTIVE Treatment with a BRAF mutation inhibitor might shrink otherwise refractory craniopharyngiomas and is a promising preoperative treatment to facilitate tumor resection. The aim of this study was to investigate the noninvasive diagnosis of BRAF-mutated craniopharyngiomas based on MRI characteristics. METHODS Fifty-two patients with pathologically diagnosed craniopharyngioma were included in this study. Polymerase chain reaction was performed on tumor tissue specimens to detect BRAF and CTNNB1 mutations. MRI manifestations-including tumor location, size, shape, and composition; signal intensity of cysts; enhancement pattern; pituitary stalk morphology; and encasement of the internal carotid artery-were analyzed by 2 neuroradiologists blinded to patient identity and clinical characteristics, including BRAF mutation status. Results were compared between the BRAF-mutated and wild-type (WT) groups. Characteristics that were significantly more prevalent (p < 0.05) in the BRAF-mutated craniopharyngiomas were defined as diagnostic features. The minimum number of diagnostic features needed to make a diagnosis was determined by analyzing the receiver operating characteristic (ROC) curve. RESULTS Eight of the 52 patients had BRAF-mutated craniopharyngiomas, and the remaining 44 had BRAF WT tumors. The clinical characteristics did not differ significantly between the 2 groups. Interobserver agreement for MRI data analysis was relatively reliable, with values of Cohen κ ranging from 0.65 to 0.97 (p < 0.001). A comparison of findings in the 2 patient groups showed that BRAF-mutated craniopharyngiomas tended to be suprasellar (p < 0.001), spherical (p = 0.005), predominantly solid (p = 0.003), and homogeneously enhancing (p < 0.001), and that patients with these tumors tended to have a thickened pituitary stalk (p = 0.014). When at least 3 of these 5 features were present, a tumor might be identified as BRAF mutated with a sensitivity of 1.00 and a specificity of 0.91. The area under the ROC curve for the sum of all 5 diagnostic criteria was 0.989 (p < 0.001). CONCLUSIONS The BRAF mutation status of craniopharyngiomas might be predicted using certain MRI features with relatively high sensitivity and specificity, thus offering potential guidance for the preoperative administration of BRAF mutation inhibitors.
IntroductionAn ideal stent would offer simple insertion and removal with no discomfort and/or migration, it would have no biofilm formation or encrustation and would also maintain the patient's quality of life.Material and methodsIn this mini-review, we outlined the engineering developments related to stent material, design and coating.ResultsThere have been a wide variety of in-vitro, model-based, animal-based and clinical studies using a range of commercial and non-commercial stents. Ureteric stents have evolved since their first usage with a wider range of stent design, material and coating available for laboratory and clinical use.ConclusionsWhile engineering innovations have led to the evolution of stents, more work needs to be done to address the issues relating to stent encrustation and biofilm formation.
Objective To construct and validate a nomogram for patients with endometrial carcinoma to predict the 3‐ and 5‐year overall survival (OS) based on the Surveillance, Epidemiology, and End Results (SEER) database. Methods Demographic and clinical pathologic characteristics of patients with endometrial carcinoma diagnosed between 1973 and 2015 were extracted from the SEER database. Univariate and multivariate Cox analyses were carried out to identify the independent characteristics and further included into the construction of a nomogram. Finally, concordance index and calibration curves were used to validate the nomogram. Results A total of 49 844 patients were enrolled into our analysis. The results of univariate Cox analysis showed that age, race, marital status, FIGO Stage, grade, and metastatic status to bone, brain, lung, or liver were significant factors. Multivariate Cox analysis was performed and it confirmed all factors as independent variables. Next, a nomogram was constructed using these independent variables in prediction of the 3‐ and 5‐year OS. Furthermore, results with concordance indices (0.852 in training set and 0.861 in validation set) and calibration curves closer to ideal curves indicated the accurate predictive ability of this nomogram. Conclusions The individualized nomogram demonstrated a good ability in prognostic prediction for patients with endometrial carcinoma.
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