Tuning the 3D Printability and Thermomechanical Properties of Radiation Shields.

Additive manufacturing, with its rapid advances in materials science, allows for researchers and companies to have the ability to create novel formulations and final parts that would have been difficult or near impossible to fabricate with traditional manufacturing methods. One such 3D printing technology, direct ink writing, is especially advantageous in fields requiring customizable parts with high amounts of functional fillers. Nuclear technology is a prime example of a field that necessitates new material design with regard to unique parts that also provide radiation shielding. Indeed, much effort has been focused on developing new rigid radiation shielding components, but DIW remains a less explored technology with a lot of potential for nuclear applications. In this study, DIW formulations that can behave as radiation shields were developed and were printed with varying amounts of porosity to tune the thermomechanical performance.

Impact of warm versus cold ischemia on renal function following partial nephrectomy.

INTRODUCTION: We evaluated renal function following partial nephrectomy with cold ischemia (CI) versus warm ischemia (WI). METHODS: Data were collected from 1,396 patients at six institutions who underwent partial nephrectomy for a renal mass with normal contralateral kidney to evaluate percent change in glomerular filtration rate (GFR) at 3-18 months. A multivariate linear regression model tested the association of percent change GFR with clinical, operative, and pathologic factors. RESULTS: A total of 874 patients (63 %) underwent PN with CI and 522 (37 %) with WI. All patients undergoing laparoscopic and robotic-assisted partial nephrectomy (n = 443) had WI, whereas 92 % of open partial nephrectomy patients (n = 953) had CI. The CI group had a lower mean baseline GFR (72 vs. 80 ml/min/1.73 m(2)), longer median ischemia time (33 vs. 29 min), and larger mean tumor size (3.2 vs. 2.9 cm) with more advanced pathologic stage (T1b-T3: 25 vs. 16 %) (all p values <0.001). Patients with CI and WI demonstrated 12.3 and 10.1 % reductions in renal function from baseline, respectively (p = 0.067). Increasing age, female gender, and increasing tumor size were associated with reduction in renal function (all p values <0.001). Neither renal hypothermia nor operative technique independently predicted reduced renal function. Sensitivity analyses limited to ischemia time >30 min, baseline estimated glomerular filtration rate <60 ml/min/1.73 m(2), or tumors >4 cm did not significantly alter the findings. CONCLUSIONS: Increasing age, female gender, and larger tumor size independently predict a decrease in renal function following partial nephrectomy with a normal contralateral kidney. Within the limitations of a non-randomized comparison, including lack of parenchymal preservation percentage, neither surgical approach (open or laparoscopic) nor presence of hypothermia appears to be associated with long-term renal function.

Chronic kidney disease before and after partial nephrectomy.

PURPOSE: We performed a multi-institutional retrospective cohort study to evaluate baseline renal function of patients who underwent partial nephrectomy for renal tumors, and determined rates of progression to higher stages of chronic kidney disease. MATERIALS AND METHODS: The Modification of Diet in Renal Disease study equation was used to estimate glomerular filtration rate. Preoperative and postoperative serum creatinine values were obtained from patients who underwent partial nephrectomy at 6 institutions with a normal contralateral kidney, and had baseline chronic kidney disease stage I (estimated glomerular filtration rate greater than 90 ml/minute/1.73 m(2)), II (estimated glomerular filtration rate 60 to 89 ml/minute/1.73 m(2)) or III (estimated glomerular filtration rate 30 to 59 ml/minute/1.73 m(2)). The end point was change in chronic kidney disease stage at long-term followup (3 to 18 months). Multivariate logistic and Cox regression models tested the association of newly acquired chronic kidney disease stage III or greater with pertinent demographic, tumor and surgical factors. RESULTS: For 1,228 patients with followup creatinine data at least 3 months after partial nephrectomy median baseline glomerular filtration rate was 74 ml/minute/1.73 m(2). At baseline 19%, 59% and 22% of patients had chronic kidney disease stage I, II and III, respectively. At long-term followup for patients with baseline chronic kidney disease stage I or II median postoperative glomerular filtration rate was 67 ml/minute/1.73 m(2) with 29% having progression to chronic kidney disease stage III or greater. Increasing age, female gender, increasing tumor size, clamping of the renal artery and vein, and lower preoperative estimated glomerular filtration rate were independently associated with newly acquired chronic kidney disease stage III or greater. The presence of comorbid conditions such as coronary artery disease, diabetes mellitus or hypertension did not independently predict an increased risk of higher chronic kidney disease stage. CONCLUSIONS: Chronic kidney disease stage III or greater will develop postoperatively in approximately a third of patients with an estimated glomerular filtration rate greater than 60 ml/minute/1.73 m(2), and this progression is associated with definable demographic, tumor and surgical factors.

Chronic Kidney Disease Epidemiology Collaboration versus Modification of Diet in Renal Disease equations for renal function evaluation in patients undergoing partial nephrectomy.

PURPOSE: A novel equation, the Chronic Kidney Disease Epidemiology Collaboration, has been proposed to replace the Modification of Diet in Renal Disease for estimated glomerular filtration rate due to higher accuracy, particularly in the setting of normal renal function. We compared these equations in patients with 2 functioning kidneys undergoing partial nephrectomy. MATERIALS AND METHODS: We assembled a cohort of 1,158 patients from 5 institutions who underwent partial nephrectomy between 1991 and 2009. Only subjects with 2 functioning kidneys were included in the study. The end points were baseline estimated glomerular filtration rate, last followup estimated glomerular filtration rate (3 to 18 months), absolute and percent change estimated glomerular filtration rate ([absolute change/baseline] × 100%), and proportion of newly developed chronic kidney disease stage III. The agreement between the equations was evaluated using Bland-Altman plots and the McNemar test for paired observations. RESULTS: Mean baseline estimated glomerular filtration rate derived from the Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration equations were 73 and 77 ml/minute/1.73 m(2), respectively, and following surgery were 63 and 67 ml/minute/1.73 m(2), respectively. Mean percent change estimated glomerular filtration rate was -12% for both equations (p = 0.2). The proportion of patients with newly developed chronic kidney disease stage III following surgery was 32% and 25%, according to the Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration equations, respectively (p = 0.001). CONCLUSIONS: For patients with 2 functioning kidneys undergoing partial nephrectomy the Chronic Kidney Disease Epidemiology Collaboration equation provides slightly higher glomerular filtration rate estimates compared to the Modification of Diet in Renal Disease equation, with 7% fewer patients categorized as having chronic kidney disease stage III or worse.

Impact of ischemia on renal function after laparoscopic partial nephrectomy: a multicenter study.

PURPOSE: We assessed the influence of renal ischemia on long-term global renal function after laparoscopic partial nephrectomy in patients with 2 functioning kidneys in a large, multicenter cohort. MATERIALS AND METHODS: Collected data included demographic, clinical and surgical characteristics, tumor parameters and renal function outcomes at 4 institutions in a total of 401 patients with 2 functioning kidneys who underwent laparoscopic partial nephrectomy. Renal function was assessed in the immediate postoperative period (days 1 to 3) and at last followup (greater than 1 month) using the estimated glomerular filtration rate calculated by the 4-variable Modification of Diet in Renal Disease equation. Ischemia time and covariates were modeled on the percent change in the estimated glomerular filtration rate using linear regression. RESULTS: Median ischemia time was 29 minutes (IQR 22, 34). The postoperative change and the last (long-term) change in the estimated glomerular filtration rate were -16% and -11%, respectively. Median time to the last estimated glomerular filtration rate measurement was 13 months (IQR 6, 24). On multivariate analysis shorter ischemia and operative times, external or ureteral irrigation with cold saline and female gender were associated with less postoperative percent change in the estimated glomerular filtration rate. Smaller tumor size and absent diabetes were associated with less of a final percent change in the estimated glomerular filtration rate. Ischemia time was not associated with a percent change in the estimated glomerular filtration rate at last followup. CONCLUSIONS: Within the range of times in these series renal ischemia did not have a clinically significant impact on global renal function in patients with 2 functioning kidneys who underwent laparoscopic partial nephrectomy, as measured by the estimated glomerular filtration rate.

Advanced patient age is associated with inferior cancer-specific survival after radical nephroureterectomy.

OBJECTIVE: To assess the impact of patient age on outcomes after radical nephroureterectomy (RNU) for upper tract urothelial carcinoma (UTUC). PATIENTS AND METHODS: Data were collected on 1453 patients treated with RNU at 13 centres. Pathological slides were reviewed by dedicated genitourinary pathologists according to standardized criteria. Age at RNU was analysed both as a continuous and categorical variable (<50, n = 85; 50-59.9, n = 229; 60-69.9, n = 416; 70-79.9, n = 523; > or =80 years, n = 200). RESULTS Patients aged <50 years were less likely to have undergone previous ureteroscopy and to have a history of bladder cancer (P < or = 0.026). Advanced age was associated with infiltrative architecture and female gender (P < or = 0.003). Patients aged >70 years were less likely to undergo lymphadenectomy and to receive adjuvant chemotherapy (P < or = 0.026). In multivariable analyses, being older was associated with decreased all-cause (AC) survival (>60 years) and cancer-specific survival (CSS; >80 years) after controlling for the effects of standard pathological features (P < or = 0.006). However, addition of age did not improve the predictive accuracy of a base model that included standard pathological features for prediction of either disease recurrence, AC survival or CSS. CONCLUSIONS: Being older at the time of RNU was associated with decreased survival. This finding could be due to a change in the biological potential of the tumour cell, a decrease in the host's defence mechanisms, or differences in care patterns. Further work is needed to improve our understanding of UTUC outcomes in this growing segment of the population and to develop strategies to improve cancer control in the elderly.

The extent of lymphadenectomy seems to be associated with better survival in patients with nonmetastatic upper-tract urothelial carcinoma: how many lymph nodes should be removed?

BACKGROUND: The role and extent of lymphadenectomy in patients with upper-tract urothelial carcinoma (UTUC) is debated. OBJECTIVE: To establish whether the number of lymph nodes (LNs) removed might be associated with better cause-specific survival in patients with UTUC. DESIGN, SETTING, AND PARTICIPANTS: The study included 552 consecutive patients who underwent radical nephroureterectomy (RNU) and lymphadenectomy between 1992 and 2006. INTERVENTION: Patients were treated with RNU and lymphadenectomy. MEASUREMENTS: Univariable and multivariable Cox proportional hazards regression models addressed the association between the number of LNs removed and cause-specific mortality (CSM). The number of LNs removed was coded as a cubic spline to allow for nonlinear effects. Finally, the most informative cut-off for the number of removed LNs was identified. RESULTS AND LIMITATIONS: In the entire population, the number of LNs removed was not associated with CSM in univariable (hazard ratio [HR]: 0.99; p=0.16) or in multivariable (HR: 0.97; p=0.12) analyses. In contrast, in the subgroup of pN0 patients (n=412), the number of LNs removed achieved the independent predictor status of CSM (HR: 0.93; p=0.02). Eight LNs removed was the most informative cut-off in predicting CSM (HR: 0.42; p=0.004). The inclusion of the variable defining dichotomously the number of removed LNs (< 8 vs > or = 8) in the base model (age, Eastern Cooperative Oncology Group performance status, pathologic stage, grade, architecture, and lymphovascular invasion) significantly increased the accuracy in predicting CSM (+1.7%; p<0.001). CONCLUSIONS: The extension of the lymphadenectomy in pN0 UTUC patients seems to be associated with CSM. Longer survival was observed in patients in whom at least eight LNs had been removed.

Impact of lymph node dissection on cancer specific survival in patients with upper tract urothelial carcinoma treated with radical nephroureterectomy.

PURPOSE: We examined the impact of lymphadenectomy on the clinical outcomes of patients with upper tract urothelial cancer treated with radical nephroureterectomy. MATERIALS AND METHODS: Data were collected on 1,130 consecutive patients with pT1-4 upper tract urothelial cancer treated with radical nephroureterectomy at 13 centers worldwide. Patients were grouped according to nodal status (pN0 vs pNx vs pN+). The choice to perform lymphadenectomy was determined by the treating surgeon. All pathology slides were reevaluated by dedicated genitourinary pathologists. Univariable and multivariable Cox regression models measured the association of nodal status (pN0 vs pNx vs pN+) with cancer specific survival. RESULTS: Overall 412 patients (36.5%) had pN0 disease, 578 had pNx disease (51.1%) and 140 had pN+ disease (12.4%). The 5-year cancer specific survival estimate was lower in patients with pN+ compared to those with pNx disease (35% vs 69%, p <0.001), which in turn was lower than that in those with pN0 disease (69% vs 77%, p = 0.024). In the subgroup of patients with pT1 disease (345) cancer specific survival rates were not different in those with pN0 and pNx. In pT2-4 cases (813) cancer specific survival estimates were lowest in pN+, intermediate in pNx and highest in pN0 (33% vs 58% vs 70%, p = 0.017). When adjusted for the effects of standard clinicopathological features pN+ was an independent predictor of cancer specific survival (p <0.001). pNx was significantly associated with worse prognosis than pN0 in pT2-4 upper tract urothelial cancer only. CONCLUSIONS: Nodal status is a significant predictor of cancer specific survival in upper tract urothelial cancer. pNx is significantly associated with a worse prognosis than pN0 in pT2-4 tumors. Patients expected to have pT2-4 disease should undergo lymphadenectomy to improve staging and thereby help guide decision making regarding adjuvant chemotherapy.

Comparison of oncologic outcomes for open and laparoscopic nephroureterectomy: a multi-institutional analysis of 1249 cases.

BACKGROUND: Data regarding the oncologic efficacy of laparoscopic nephroureterectomy (LNU) compared to open nephroureterectomy (ONU) are scarce. OBJECTIVE: We compared recurrence and cause-specific mortality rates of ONU and LNU. DESIGN, SETTING, AND PARTICIPANTS: Thirteen centers from three continents contributed data on 1249 patients with nonmetastatic upper tract urothelial carcinoma (UTUC). MEASUREMENTS: Univariable and multivariable survival models tested the effect of procedure type (ONU [n=979] vs LNU [n=270]) on cancer recurrence and cancer-specific mortality. Covariables consisted of institution, age, Eastern Cooperative Oncology Group (ECOG) performance status score, pT stage, pN stage, tumor grade, lymphovascular invasion, tumor location, concomitant carcinoma in situ, ureteral cuff management, previous urothelial bladder cancer, and previous endoscopic treatment. RESULTS AND LIMITATIONS: Median follow-up for censored cases was 49 mo (mean: 62). Relative to ONU, LNU patients had more favorable pathologic stages (pT0/Ta/Tis: 38.1% vs 20.8%, p<0.001) and less lymphovascular invasion (14.8% vs 21.3%, p=0.02) and less frequently had tumors located in the ureter (64.5 vs 71.1%, p=0.04). In univariable recurrence and cancer-specific mortality models, ONU was associated with higher cancer recurrence and mortality rates compared to LNU (hazard ratio [HR]: 2.1 [p<0.001] and 2.0 [p=0.008], respectively). After adjustment for all covariates, ONU and LNU had no residual effect on cancer recurrence and mortality (p=0.1 for both). CONCLUSIONS: Short-term oncologic data on LNU are comparable to ONU. Since LNU was selectively performed in favorable-risk patients, we cannot state with certainty that ONU and LNU have the same oncologic efficacy in poor-risk patients. Long-term follow-up data and morbidity data are necessary before LNU can be considered as the standard of care in patients with muscle-invasive or high-grade UTUC.

Tumour architecture is an independent predictor of outcomes after nephroureterectomy: a multi-institutional analysis of 1363 patients.

OBJECTIVE: To assess whether tumour architecture can help to refine the prognosis of patients treated with nephroureterectomy (NU) for urothelial carcinoma (UC) of the upper urinary tract (UT), as the prognostic value of tumour architecture (papillary vs sessile) in UTUC remains elusive. PATIENTS AND METHODS: The study included 1363 patients with UTUC and treated with radical NU at 12 centres worldwide. All slides were re-reviewed according to strict criteria by genitourinary pathologists who were unaware of the findings of the original pathology slides and clinical outcomes. Gross tumour architecture was categorized as sessile vs papillary. RESULTS: Papillary growth was identified in 983 patients (72.2%) and sessile growth in 380 (27.8%). The sessile growth pattern was associated with higher tumour grade, more advanced stage, lymphovascular invasion, and metastasis to lymph nodes (all P < 0.001). In multivariable Cox regression analyses that adjusted for the effects of pathological stage, grade and lymph node status, tumour architecture (sessile or papillary) was an independent predictor of cancer recurrence (hazard ratio 1.5, P = 0.002) and cancer-specific mortality (1.6, P = 0.001). Adding tumour architecture increased the predictive accuracy of a model that comprised pathological stage, grade and lymph node status for predicting cancer recurrence and cancer-specific death by a minimal but statistically significant margin (gain in predictive accuracy 1% and 0.5%, both P < 0.001). CONCLUSION: The tumour architecture of UTUC is associated with established features of biologically aggressive disease, and more importantly, with prognosis after radical NU. Including tumour architecture in predictive models for disease progression should be considered, aiming to identify patients who might benefit from early systemic therapeutic intervention.

Peri-operative renal function and outcome after orthotopic heart transplantation.

BACKGROUND: Renal insufficiency is an established risk factor in patients undergoing cardiovascular surgery. We sought to evaluate the relationship between renal function and outcomes after orthotopic heart transplantation (OHT). METHODS: We conducted a retrospective review of 622 adults who underwent 628 consecutive OHTs between 1994 and 2001 at our institution. The recipients were divided into either normal (Group 1) or impaired (Group 2) pre-operative renal function. Impaired renal function was defined as creatinine clearance (CrCl) < 40 ml/min (Cockroft-Gault formula). Meanwhile, patients in Group 1 (normal) were defined by CrCl > or = 40 ml/min. The primary end points of the study were early and late mortality. The secondary end point included post-operative renal failure defined by the requirement of dialysis or renal allograft in the early post-operative period. The Kaplan-Meier method was used to determine actuarial survival. RESULTS: Early mortality was 7% (38/531) in Group 1 and 17% (16/96) in Group 2 (p = 0.002). Similarly, the death rate per 100 patient-years was 4.8 and 8.1 for the groups, respectively (p = 0.03). Nine percent of patients in Group 1 required post-operative dialysis (49/531), whereas 32% of recipients in Group 2 required this intervention (31/96) (p < 0.001). Early mortality was 41% for patients requiring post-operative dialysis and 3% for those not requiring such intervention (p < 0.001). Early mortality after post-operative dialysis was 41% (20/49) in Group 1 and 42% (13/31) in Group 2 (p = 0.2). CONCLUSIONS: CrCl < 40 ml/min is a useful marker for increased post-operative renal failure and mortality. Recipients who require post-operative dialysis have greatly increased mortality regardless of pre-operative CrCl. Dialysis in patients after heart transplantation carries a prohibitive risk. Dialysis as a bridge to renal transplantation may reduce this high mortality rate.