Self-expanding metal stent placement and pathological alterations among obstructive colorectal cancer cases

BACKGROUND Experimental studies suggest that self-expanding metal stents(SEMSs)enhance the aggressive behavior of obstructive colorectal cancer.The influence of SEMS placement on pathological alterations remains to be elucidated.AIM To determine whether SEMS placement is associated with molecular or pathological features of colorectal carcinoma tissues.METHODS Using a nonbiased molecular pathological epidemiology database of patients with obstructive colorectal cancers,we examined the association of SEMS placement with molecular or pathological features,including tumor size,histological type,American Joint Committee on Cancer(AJCC)-pTNM stage,and mutation statuses in colorectal cancer tissues compared with the use of transanal tubes.A multivariable logistic regression model was used to adjust for potential confounders.RESULTS SEMS placement was significantly associated with venous invasion(P<0.01),but not with the other features examined,including tumor size,disease stage,mutation status,and lymphatic invasion.In both the univariable and multivariable models with adjustment for potential factors including tumor location,histological type,and AJCC-pT stage,SEMS placement was significantly associated with severe venous invasion(P<0.01).For the outcome category of severe venous invasion,the multivariable odds ratio for SEMS placement relative to transanal tube placement was 19.4(95%confidence interval:5.24–96.2).No significant differences of disease-free survival and overall survival were observed between SEMS and transanal tube groups.CONCLUSION SEMS placement might be associated with severe venous invasion in colorectal cancer tissue,providing an impetus for further investigations on the pathological alterations by SEMSs in colorectal cancer development.

Surface Modification of NaCl Particles with Metal Films Using the Polygonal Barrel-Sputtering Method

In this study, the surfaces of NaCl particles were modified with metal films using the polygonal barrel-sputtering method. When Pt was sputtered on NaCl particles, the individual particles changed from white to metallic. Characterization of the treated samples indicated that thin Pt metal films were uniformly deposited on the NaCl particles. Immersion of the treated NaCl particles in water revealed that they floated to the surface of the water with the increase in the immersion time, although their original cubic shapes remained unchanged. The floating phenomenon of the Pt-coated NaCl particles, as mentioned above, suggests that NaCl was dissolved by the permeation of water through invisible defects such as grain boundaries in the Pt films, leading to the formation of hollow particle-like materials. It should be noted that uniform film deposition on the NaCl particles could also be achieved by sputtering with Au or Cu. Based on the obtained results, our sputtering method allows uniform surface modification of water-soluble and water-reactive powders that cannot be treated by conventional wet process using water.