Electrochemical constant current linear polarization and atomic absorption spectroscopy were used to measure the corrosion rate of coronary stents made of 316L and 317L stainless steel in 30 degrees C Tyrode's solution. The results indicated that the corrosion rate of 316L and 317L stainless steel was 21 X 10(-3) microm/a, 9.8 X 10(-3) microm/a and 0.8 X 10(-3) m/a, 0.6 X 10(-3) microm/a, respectively. All corrosion rates were lower than the medical materials corrosion rate criteria, i.e. 0.25 microm/a. Moreover the corrosion resistance of 317L stainless steel was much higher than that of 316L stainless steel. The results from atomic absorption spectroscopy may correctly reflect the quantity of releasing metal ions in the solution.
Biocompatible Materials ; chemistry ; Corrosion ; Materials Testing ; Spectrophotometry, Atomic ; Stainless Steel ; chemistry ; Stents ; Surface Properties

The corrosion rates of TiNi, CoCrNiW and CoCrNiMo were measured in Tyrode's solution with potentiodynamic linear polarization, fore-point weak polarization, Cao Chunan weak polarization, transient linear polarization and atomic absorption spectroscopy. Results indicated that corrosion rates of these three alloys were very low due to their excellent corrosion resistance and the corrosion resistance of CoCrNiMo was the best. Corrosion rates of TiNi, CoCrNiW and CoCrNiMo were 0.691, 0.0595, 0.0490 micron/a and 0.0528, 0.0383, 0.0387 micron/a, respectively. The results measured by the first three methods were about ten times of those by the latter two methods, this was related to the applicability of each method and the alloy surface state. Transient linear polarization technique can determine low corrosion rate conveniently and quickly. Atomic absorption spectroscopy method, determining directly the concentration of ion in solution, and thus provide reference for material biocompatibility. And these two methods are properly used in measuring corrosion rates for biomedical materials.
Biocompatible Materials ; chemistry ; Cobalt ; chemistry ; Corrosion ; Materials Testing ; methods ; Nickel ; chemistry ; Spectrophotometry, Atomic ; Titanium ; chemistry

Adolescent ; Adult ; Antigens, CD34 ; blood ; Case-Control Studies ; Eosinophils ; Female ; Humans ; Interleukin-5 ; blood ; Leukocyte Count ; Male ; Middle Aged ; Rhinitis, Allergic, Perennial ; blood ; Young Adult

Intraductal papillary mucinous neoplasm (IPMN) is one of the precancerous lesions of the pancreas. Currently there is controversial over the management and follow-up strategy of IPMN, including the timing of surgery. The core problem lies in the accurate preoperative assessment of the nature of the lesions and the risk of malignant transformation. Cumulation of high-quality evidence and development of efficient evaluation methods are vital for the establishment of standardized decision-making system and the improvement of clinical benefits to patients. This review aims to summarize the consensus and controversies on surgical evaluation standards in the latest guidelines and representative literatures, and to look forward to the development direction of IPMN diagnosis and treatment decisions in combination with the progress of related evaluation techniques.

The electrochemical mechanism of austenitic stainless steel (SUS316L and SUS317L) coronary stents in flowing artificial body fluid has been investigated with electrochemical technologies. The results indicated that the flowing medium coursed the samples' pitting potential Eb shift negatively, increased the pitting corrosion sensitivity, accelerated its anodic dissolution, but had little effects on repassivated potential. The flowing environment had great effects on cathodic process. The oxygen reaction on the samples' surface became faster as the cathodic process was not controlled by oxygen diffusion but by mixed diffusion and electrochemical process. With the increase of velocity of solution, the pitting corrosion becomes liable to occur under this circumstance.
Biocompatible Materials ; chemistry ; Body Fluids ; chemistry ; Corrosion ; Electrochemistry ; Materials Testing ; Stainless Steel ; chemistry ; Stents

Objective:To study the differences in preoperative examination indexes between pancreatic head cancer and distal bile duct cancer, and to establish a preliminary prediction model to provide reference for clinical decision-making.Methods:Retrospective analysis was conducted on 243 consecutive patients who underwent open radical pancreaticoduodenectomy from January 1, 2015 to December 31, 2019 at the Chinese PLA General Hospital. There were 177 males and 66 females, aged (58.9±8.9) years old. Based on postoperative pathological results, these 243 patients were divided into the pancreatic head cancer group ( n=113) and the distal bile duct cancer group ( n=130). The clinical data of the two groups were collected. Minimum absolute value convergence and selection operator regression were used to screen the best predictors of pancreatic head cancer. The rms package was used to construct the nomogram model, and k-fold cross was used for internal validation. Results:Seven best predictive indexes are selected: age, rate of weight loss, main pancreatic duct diameter, neutrophil/lymphocyte, DTR (DBil/TBil), carcinoembryonic antigen and CA125. Based on these indexes, a nomogram prediction model was constructed with the C-index of 0.868 after k-fold cross-validation, indicating that discrimination of the model to be acceptable. Validation using calibration curve exhibited good concordance between the predicted probability with the ideal probability ( P=0.728). Conclusion:The nomogram prediction model established in this study effectively predicted patients with pancreatic head cancer, and helped preoperatively to differentiate pancreatic head cancer from distal cholangiocarcinoma.

Objective:To study the risk factors for early recurrence of patients undergoing radical pancreaticoduodenectomy (PD) for pancreatic ductal adenocarcinoma (PDAC) and construct a normogram model.Methods:Patients undergoing open radical PD for PDAC at Faculty of Hepato-Pancreato-Biliary Surgery, Chinese PLA General Hospital from January 2014 to December 2021 were retrospectively screened. A total of 213 patients were enrolled, including 145 males and 68 females, aged (58.4±9.8) years. Patients were divided into the early recurrence group ( n=59, recurrence within 6 months after surgery) and a control group ( n=154, no recurrence within 6 months after surgery). Using minimum absolute value convergence and selection operator regression (LASSO) and multi-factor logistic regression analysis, we screened out the best predictor of early recurrence after PD for PDAC, and then established a nomogram model. The effectiveness of the model was validated by receiver operating characteristic (ROC) curve, calibration curves, and decision analysis curves. Results:Multivariate logistic regression analysis showed that patients with obstructive jaundice, vascular invasion, massive intraoperative bleeding, high-risk tumors (poorly differentiated or undifferentiated), high carbohydrate antigen 19-9 to total bilirubin ratio, and high fibrinogen and neutrophil to lymphocyte ratio scores had a higher risk of early postoperative recurrence. Based on the indexes above, a nomogram prediction model was constructed. The area under the ROC curve was 0.797 (95% CI: 0.726-0.854). Validation of the calibration curve exhibited good concordance between the predicted probability and ideal probability, decision curve analysis showed that the net benefits of the groupings established according to the model were all greater than 0 within the high risk threshold of 0.08 to 1.00. Conclusion:The nomogram for predicting early recurrence after PD for PDAC has a good efficiency, which could be helpful to screen out the high-risk patients for adjuvant or neoadjuvant therapy.

Desmoplastic stroma of pancreatic ductal adenocarcinoma plays an important role in tumor progression and treatment resistance. Stroma-targeted therapies are therefore promising for clinical application and extensive related researches are undergoing. In this article, recent advances in stromal targeting strategies were reviewed from three perspectives: cancer-associated fibroblasts, extracellular matrix and angiogenesis, and an outlook for the future of this strategy was also provided.

Objective:To construct a predictive nomogram on postoperative overall survival (OS) in patients with pancreatic ductal adenocarcinoma (PDAC) after R 0 radical pancreaticoduodenectomy, and to evaluate its performance. Methods:The clinicopathological data of patients who underwent radical pancreaticoduodenectomy at the Faculty of Hepato-Pancreato-Biliary Surgery, Chinese PLA General Hospital from January 2014 to December 2019 for pathologically diagnosed PDAC were retrospectively collected and analyzed. There were 119 patients, with 85 males and 34 females, aged (58±11) years. Using multivariate Cox regression analysis (stepwise regression), a prediction nomogram was constructed. Concordance index (C-index), calibration curve, and time-dependent receiver operating characteristic (ROC) curve were applied to evaluate the predictive performance.Results:The 1-, 2-, and 3-year cumulative survival rates of these 119 patients were 67.2%, 35.0%, and 24.8%, respectively. High-grade tumors (poorly differentiated and undifferentiated), vascular carcinoma embolus, systemic immune inflammatory index <279.4×10 9/L, prognostic nutritional index <40.5, alanine aminotransferase-to-aspartate aminotransferase ratio>1.1, total bilirubin>258.5 μmol/L and plasma fibrinogen>3.43 g/L were independent risk factors for poor OS for PDAC patients after radical pancreaticoduodenectomy (all P<0.05). These indicators, together with age >63 years, constituted the regression formula for prediction with a C-index=0.74. The areas under the curve of ROC for the nomogram on predicting survival were 0.795, 0.803, and 0.836 at 1, 2, and 3-year respectively, and only slight deviations were observed on the calibration curves from the standard 45° line, suggesting that the survival prediction of the model in this dataset fitted well with the actual survival status. Conclusion:The predictive nomogram on OS in patients after R 0 radical pancreaticoduodenectomy based on the clinicopathological characteristics of PDAC was internally validated to have a good predictive performance on OS. The nomogram can help to optimize prognostic risk stratification and treatment decisions for this subgroup of patients. This prediction model needs to be further verified and improved by using large-scale cohort studies.

Objective:To assess the predictive value of aspartate aminotransferase-to-alanine amino-transferase ratio (DRR) on overall survival of patients with pancreatic ductal adenocarcinoma (PDAC) who underwent radical pancreaticoduodenectomy.Methods:A retrospective analysis was performed on the clinical data of 137 patients who underwent radical pancreaticoduodenectomy and were diagnosed with PDAC postoperatively at the Chinese PLA General Hospital from January 2015 to December 2020. There were 97 male and 40 female patients, with an average age of (58±10) years old. The patients were grouped according to the optimal survival risk cutoff value of DRR, and the differences in key clinical and pathological indicators between the groups were compared. Kaplan-Meier method was used for survival analysis, and log-rank test was used for comparison of survival rates. Multivariate Cox analysis was performed to evaluate the prognostic factors affecting survival.Results:The 137 PDAC patients were divided into two groups based on the optimal cutoff value of DRR, namely 1.1: DRR≥1.1 was defined as the high-DRR group ( n=29), and DRR<1.1 was defined as the low-DRR group ( n=108). The cumulative survival rate of the low-DRR group was better than that of the high-DRR group, and the difference was statistically significant ( P=0.003). The results of the multivariate Cox regression analysis showed that DRR≥1.1 ( HR=2.485, 95% CI: 1.449-4.261, P=0.001), preoperative biliary drainage ( HR=1.845, 95% CI: 1.030-3.306, P=0.039), lymph node metastasis N2 stage ( HR=2.240, 95% CI: 1.123-4.470, P=0.022), high tumor differentiation ( HR=2.001, 95% CI: 1.279-3.129, P=0.002), and intravascular cancer emboli ( HR=2.240, 95% CI: 1.123-4.470, P=0.022) were risk factors for poor overall survival in PDAC patients who underwent radical pancreaticoduodenectomy. Conclusion:DRR has predictive value for overall survival after surgery in PDAC patients undergoing radical pancreatoduodenectomy. A DRR of 1.1 or greater is a risk factor for poor overall survival after surgery in PDAC patients.