475 research outputs found

    Parameters of the attenuated schistosome vaccine evaluated in the olive baboon

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    Five exposures of baboons to the attenuated schistosome vaccine gave greater protection than three exposures, but this attenuation was not sustained when challenge was delayed. Within the scope of the data collected, fecal egg counts and circulating antigen levels did not accurately predict the observed worm burdens. Levels of immunoglobulin G at challenge correlated best with protection, but there was little evidence of a recall response

    Randomly generated polytopes for testing mathematical programming algorithms

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    Randomly generated polytopes are used frequently to test and compare algorithms for a variety of mathematical programming problems. These polytopes are constructed by generating linear inequality constraints with coefficients drawn independently from a distribution such as the uniform or the normal. It is noted that this class of 'random' polytopes has a special property: the angles between the hyperplanes, though dependent on the specific distribution used, tend to be equal when the dimension of the space increases. Obviously this structure of 'random' polytopes may bias test results

    Should jaundice preclude resection in patients with gallbladder cancer? Results from a nation-wide cohort study

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    Background: It is controversial whether patients with gallbladder cancer (GBC) presenting with jaundice benefit from resection. This study re-evaluates the impact of jaundice on resectability and survival. Methods: Data was collected on surgically explored GBC patients in all Dutch academic hospitals from 2000 to 2018. Survival and prognostic factors were assessed. Results: In total 202 patients underwent exploration and 148 were resected; 124 non-jaundiced patients (104 resected) and 75 jaundiced patients (44 resected). Jaundiced patients had significantly (P < 0.05) more pT3/T4 tumors, extended (≥3 segments) liver- and organ resections, major post-operative complications and margin-positive resection. 90-day mortality was higher in jaundiced patients (14% vs. 0%, P < 0.001). Median overall survival (OS) was 7.7 months in jaundiced patients (2-year survival 17%) vs. 26.1 months in non-jaundiced patients (2-year survival 39%, P < 0.001). In multivariate analysis, jaundice (HR1.89) was a poor prognostic factor for OS in surgically explored but not in resected patients. Six jaundiced patients did not develop a recurrence; none had liver- or common bile duct (CBD) invasion on imaging. Conclusion: Jaundice is associated with poor survival. However, jaundice is not an independent adverse prognostic factor in resected patients. Surgery should be considered in patients with limited disease and no CBD invasion on imaging

    Extended resections for advanced gallbladder cancer: results from a nationwide cohort study

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    Background Extended resections (i.e., major hepatectomy and/or pancreatoduodenectomy) are rarely performed for gallbladder cancer (GBC) because outcomes remain inconclusive. Data regarding extended resections from Western centers are sparse. This Dutch, multicenter cohort study analyzed the outcomes of patients who underwent extended resections for locally advanced GBC. Methods Patients with GBC who underwent extended resection with curative intent between January 2000 and September 2018 were identified from the Netherlands Cancer Registry. Extended resection was defined as a major hepatectomy (resection of >= 3 liver segments), a pancreatoduodenectomy, or both. Treatment and survival data were obtained. Postoperative morbidity, mortality, survival, and characteristics of short- and long-term survivors were assessed. Results The study included 33 patients. For 16 of the patients, R0 resection margins were achieved. Major postoperative complications (Clavien Dindo >= 3A) occurred for 19 patients, and 4 patients experienced postoperative mortality within 90 days. Recurrence occurred for 24 patients. The median overall survival (OS) was 12.8 months (95% confidence interval, 6.5-19.0 months). A 2-year survival period was achieved for 10 patients (30%) and a 5-year survival period for 5 patients (15%). Common bile duct, liver, perineural and perivascular invasion and jaundice were associated with reduced survival. All three recurrence-free patients had R0 resection margins and no liver invasion. Conclusion The median OS after extended resections for advanced GBC was 12.8 months in this cohort. Although postoperative morbidity and mortality were significant, long-term survival (>= 2 years) was achieved in a subset of patients. Therefore, GBC requiring major surgery does not preclude long-term survival, and a subgroup of patients benefit from surgery.Transplant surger

    Prognostic value of total tumor volume in patients with colorectal liver metastases:A secondary analysis of the randomized CAIRO5 trial with external cohort validation

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    Background:This study aimed to assess the prognostic value of total tumor volume (TTV) for early recurrence (within 6 months) and overall survival (OS) in patients with colorectal liver metastases (CRLM), treated with induction systemic therapy followed by complete local treatment.Methods: Patients with initially unresectable CRLM from the multicenter randomized phase 3 CAIRO5 trial (NCT02162563) who received induction systemic therapy followed by local treatment were included. Baseline TTV and change in TTV as response to systemic therapy were calculated using the CT scan before and the first after systemic treatment, and were assessed for their added prognostic value. The findings were validated in an external cohort of patients treated at a tertiary center. Results:In total, 215 CAIRO5 patients were included. Baseline TTV and absolute change in TTV were significantly associated with early recurrence (P = 0.005 and P = 0.040, respectively) and OS in multivariable analyses (P = 0.024 and P = 0.006, respectively), whereas RECIST1.1 was not prognostic for early recurrence (P = 0.88) and OS (P = 0.35). In the validation cohort (n = 85), baseline TTV and absolute change in TTV remained prognostic for early recurrence (P = 0.041 and P = 0.021, respectively) and OS in multivariable analyses (P &lt; 0.0001 and P = 0.012, respectively), and showed added prognostic value over conventional clinicopathological variables (increase C-statistic, 0.06; 95 % CI, 0.02 to 0.14; P = 0.008). Conclusion: Total tumor volume is strongly prognostic for early recurrence and OS in patients who underwent complete local treatment of initially unresectable CRLM, both in the CAIRO5 trial and the validation cohort. In contrast, RECIST1.1 did not show prognostic value for neither early recurrence nor OS.</p

    Extended Resections for Advanced Gallbladder Cancer: Results from a Nationwide Cohort Study

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    Background: Extended resections (i.e., major hepatectomy and/or pancreatoduodenectomy) are rarely performed for gallbladder cancer (GBC) because outcomes remain inconclusive. Data regarding extended resections from Western centers are sparse. This Dutch, multicenter cohort study analyzed the outcomes of patients who underwent extended resections for locally advanced GBC. Methods: Patients with GBC who underwent extended resection with curative intent between January 2000 and September 2018 were identified from the Netherlands Cancer Registry. Extended resection was defined as a major hepatectomy (resection of ≥ 3 liver segments), a pancreatoduodenectomy, or both. Treatment and survival data were obtained. Postoperative morbidity, mortality, survival, and characteristics of short- and long-term survivors were assessed. Results: The study included 33 patients. For 16 of the patients, R0 resection margins were achieved. Major postoperative complications (Clavien Dindo ≥ 3A) occurred for 19 patients, and 4 patients experienced postoperative mortality within 90 days. Recurrence occurred for 24 patients. The median overall survival (OS) was 12.8 months (95% confidence interval, 6.5–19.0 months). A 2-year survival period was achieved for 10 patients (30%) and a 5-year survival period for 5 patients (15%). Common bile duct, liver, perineural and perivascular invasion and jaundice were associated with reduced survival. All three recurrence-free patients had R0 resection margins and no liver invasion. Conclusion: The median OS after extended resections for advanced GBC was 12.8 months in this cohort. Although postoperative morbidity and mortality were significant, long-term survival (≥ 2 years) was achieved in a subset of patients. Therefore, GBC requiring major surgery does not preclude long-term survival, and a subgroup of patients benefit from surgery

    Venous wedge and segment resection during pancreatoduodenectomy for pancreatic cancer: impact on short- and long-term outcomes in a nationwide cohort analysis

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    Background Venous resection of the superior mesenteric or portal vein is increasingly performed in pancreatic cancer surgery, whereas results of studies on short- and long-term outcomes are contradictory. The aim of this study was to evaluate the impact of the type of venous resection in pancreatoduodenectomy for pancreatic cancer on postoperative morbidity and overall survival. Methods This nationwide retrospective cohort study included all patients who underwent pancreatoduodenectomy for pancreatic cancer in 18 centres (2013-2017). Results A total of 1311 patients were included, of whom 17 per cent underwent wedge resection and 10 per cent segmental resection. Patients with segmental resection had higher rates of major morbidity (39 versus 20 versus 23 per cent, respectively; P < 0.001) and portal or superior mesenteric vein thrombosis (18 versus 5 versus 1 per cent, respectively; P < 0.001) and worse overall survival (median 12 versus 16 versus 20 months, respectively; P < 0.001), compared to patients with wedge resection and those without venous resection. Multivariable analysis showed patients with segmental resection, but not those who had wedge resection, had higher rates of major morbidity (odds ratio = 1.93, 95 per cent c.i. 1.20 to 3.11) and worse overall survival (hazard ratio = 1.40, 95 per cent c.i. 1.10 to 1.78), compared to patients without venous resection. Among patients who received neoadjuvant therapy, there was no difference in overall survival among patients with segmental and wedge resection and those without venous resection (median 32 versus 25 versus 33 months, respectively; P = 0.470), although there was a difference in major morbidity rates (52 versus 19 versus 21 per cent, respectively; P = 0.012). Conclusion In pancreatic surgery, the short- and long-term outcomes are worse in patients with venous segmental resection, compared to patients with wedge resection and those without venous resection.Of 1311 patients who underwent pancreatoduodenectomy, 17 per cent underwent venous wedge resection and 10 per cent underwent venous segmental resection. Venous segmental, but not venous wedge, resection was associated with higher major morbidity rates (odds ratio = 1.93, 95 per cent c.i. 1.20 to 3.11) and worse overall survival (hazard ratio = 1.40, 95 per cent c.i. 1.10 to 1.78), compared to no venous resection. This nationwide study found worse short- and long-term outcomes in patients who had venous segmental resection. The results of this study urge the need for improving outcomes in patients who require venous segmental resection.Surgical oncolog

    Random polytopes: Their definition, generation and aggregate properties

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    The definition of random polytope adopted in this paper restricts consideration to those probability measures satisfying two properties. First, the measure must induce an absolutely continuous distribution over the positions of the bounding hyperplanes of the random polytope; and second, it must result in every point in the space being equally as likely as any other point of lying within the random polytope. An efficient Monte Carlo method for their computer generation is presented together with analytical formulas characterizing their aggregate properties. In particular, it is shown that the expected number of extreme points for such random polytopes increases monotonically in the number of constraints to the limiting case of a polytope topologically equivalent to a hypercube. The implied upper bound of 2 n where n is the dimensionality of the space is significantly less than McMullen's attainable bound on the maximal number of vertices even for a moderate number of constraints.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47911/1/10107_2005_Article_BF01585093.pd
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