A MapReduce Framework for Analysing Portfolios of Catastrophic Risk with Secondary Uncertainty

AbstractThe design and implementation of an extensible framework for performing exploratory analysis of complex property portfolios of catastrophe insurance treaties on the Map-Reduce model is presented in this paper. The framework implements Aggregate Risk Analysis, a Monte Carlo simulation technique, which is at the heart of the analytical pipeline of the modern quantitative insurance/reinsurance pipeline. A key feature of the framework is the support for layering advanced types of analysis, such as portfolio or program level aggregate risk analysis with secondary uncertainty (i.e. computing Probable Maximum Loss (PML) based on a distribution rather than mean values). Such in-depth analysis is not supported by production-based risk management systems since they are constrained by hard response time requirements placed on them. On the other hand, this paper reports preliminary experimental results to demonstrate that in-depth aggregate risk analysis can be realized using a framework based on the MapReduce model

Radiological evidence of lymphangioleiomyomatosis in female and male patients with tuberous sclerosis complex

Item does not contain fulltextAIM: To determine the gender-specific prevalence of pulmonary cysts typical for lymphangioleiomyomatosis (LAM) in adult patients with known tuberous sclerosis complex (TSC). MATERIALS AND METHODS: A retrospective, cross-sectional study in a cohort of 206 adult TSC patients was performed. Institutional review board approval was obtained, and patient informed consent was waived. Patients had routinely undergone abdominal CT scanning between 1996 and 2006. All 186 patients (mean age 38 years; range 19-72 years; 91 (49%) male patients) in whom at least the lung bases were depicted on computed tomography (CT) were included. Images were reviewed for the presence of pulmonary thin-walled cysts. Descriptive statistics, two sample t-test to compare means, and chi(2)-test to compare proportions were applied. RESULTS: CT demonstrated pulmonary thin-walled cysts in the lung bases in 52 (28%) of 186 patients. Size varied from 2mm in diameter to more than 2 cm. Pulmonary cysts were detected in 40 (42%) of 95 female patients and in 12 (13%) of 91 male patients (p<0.001). In general, cysts were larger and more numerous in women than in men. Only minimal cystic changes were found in four women and two men, moderate cystic changes were seen in three women and seven men, but considerable cystic changes were seen almost exclusively in women (33 women versus three men). CONCLUSION: CT demonstrated thin-walled pulmonary cysts in the lung bases in 28% of 186 included patients with tuberous sclerosis complex. Female patients were more affected than male patients

Focal fatty areas in the myocardium of patients with tuberous sclerosis complex: a unique finding

Item does not contain fulltextWith this collection of computed tomography and magnetic resonance images, we illustrate a recently described novel finding in the myocardium of patients with tuberous sclerosis complex

Prevalence of subependymal giant cell tumors in patients with tuberous sclerosis and a review of the literature.

Item does not contain fulltextBACKGROUND AND PURPOSE: To investigate the prevalence of subependymal giant cell ependymomas (SEGA) in patients with tuberous sclerosis complex (TSC). METHODS: We performed a retrospective cross-sectional study in a cohort of 285 patients with known TSC. Institutional review board approval was obtained. We included all 214 TSC-patients who had received a contrast-enhanced computed tomography (CT) scan of the brain. The most recent scan was evaluated for SEGA and presence of hydrocephalus. Additionally, a literature search was performed, and pooled estimates of SEGA prevalence in TSC were calculated. We used descriptive statistics, two sample t-test, chi-squared-test, and meta-analysis as appropriate. RESULTS: Computed tomography showed radiological evidence of SEGA in 43 of the 214 TSC-patients (20%); 23 of 105 men (22%) and 20 of 109 women (18%; P = .52). Average maximum tumor size was 11.4 mm (range, 4-29 mm). Patients with SEGA (mean, 31 years; range, 16-58 years) were on average younger than patients without SEGA (mean, 37 years; range, 10-72 years; P = 0.007). No association between tumor size and patient age was detected. Nine patients had bilateral SEGA. Hydrocephalus was present in six of the 43 patients (14%). Meta-analysis of reported prevalence and our current study showed that studies using radiological evidence to diagnose SEGA gave a higher pooled estimate of the prevalence of SEGA in TSC (0.16; 95% CI: 0.12, 0.21) than studies using mainly histopathological evidence of SEGA (0.09; 95% CI: 0.07, 0.12). CONCLUSIONS: In our cohort, CT demonstrated evidence of SEGA in 20% of TSC-patients. Prevalence of SEGA in TSC is higher in studies using radiological evidence to diagnose SEGA than in studies using histopathological evidence

Echocardiographic screening results in patients with tuberous sclerosis complex.

Contains fulltext : 88782.pdf (publisher's version ) (Closed access)We sought to examine the frequency of abnormal echocardiographic findings in patients with tuberous sclerosis complex. In a retrospective cohort study, we included all patients with known tuberous sclerosis complex who had been sent to our cardiology department for echocardiographic screening from 1995 through August 2003 (n=56). Two research scientists independently reviewed the reports of the echocardiographic screening examinations for abnormal findings. We used descriptive statistics, the Mann-Whitney U test, and the chi(2) test. The mean age of patients included in the study was 35 years (range, 12-73 yr); 23 patients were male. Abnormal findings were seen in 22 patients (39%). The most common abnormal findings were focal areas of increased intramyocardial echogenicity, which were seen in 16 patients (29%). The clinical consequence of this finding is still unknown. We conclude that echocardiographic abnormalities are common in patients with tuberous sclerosis complex

IDH1 mutations in low-grade astrocytomas predict survival but not response to temozolomide.

Contains fulltext : 80414.pdf (publisher's version ) (Closed access)BACKGROUND: Mutations in isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) have been implicated in tumorigenesis of gliomas. Patients with high-grade astrocytomas with IDH1 or IDH2 mutations were reported to have a better survival, but it is unknown if this improved survival also holds for low-grade astrocytoma and whether these mutations predict outcome to specific treatment. METHODS: We retrospectively investigated the correlation of IDH1 and IDH2 mutations with overall survival and response to temozolomide in a cohort of patients with dedifferentiated low-grade astrocytomas treated with temozolomide at the time of progression after radiotherapy. RESULTS: IDH1 mutations were present in 86% of the 49 progressive astrocytomas. No mutations in IDH2 were found. Presence of IDH1 mutations were early events and significantly improved overall survival (median survival 48 vs 98 months), but did not affect outcome of temozolomide treatment. CONCLUSION: These results indicate that IDH1 mutations identify a subgroup of gliomas with an improved survival, but are unrelated to the temozolomide response

PCV chemotherapy for recurrent glioblastoma multiforme.

The authors evaluated response, time to progression (TTP), survival, prognostic factors, and toxicity in 63 patients with a recurrent glioblastoma multiforme treated with procarbazine, lomustine, and vincristine (PCV) chemotherapy. Complete and partial response was observed in two (3%) and five patients (8%). In 16 patients (25%), stable disease was observed. Median TTP and survival were 13 and 33 weeks. Age or = 90 were associated with longer TTP and survival. PCV treatment was generally well tolerated

Pregnancy-related hemangioblastoma progression and complications in von Hippel-Lindau disease

OBJECTIVE: We studied the reciprocal effect of pregnancy and von Hippel-Lindau (VHL) disease by analyzing the influence of pregnancy on VHL disease- related lesions and VHL disease on pregnancy outcome. METHODS: Medical charts and imaging reports from the VHL disease expertise centers in the Netherlands were used to retrospectively assess lesion progression score before and after pregnancy and to obtain data on pregnancy outcome and VHL disease-related lesions. The Friedman test was used for analysis (p </= 0.05). Twenty-nine patients were studied (48 pregnancies, 49 newborns). RESULTS: The progression score of cerebellar hemangioblastomas significantly changed between the single MRI scan before and the 2 scans after pregnancy (p = 0.049) (n = 12). Fetal mortality rate was 2% (n = 1) caused by maternal pheochromocytoma. Maternal VHL disease-related complications occurred in 17% (n = 8) of all pregnancies. In 4 patients, a life-threatening situation emerged: hydrocephalus due to cerebellar hemangioblastoma (n = 2) and pheochromocytoma (n = 2). CONCLUSIONS: Pregnancy in patients with VHL disease induces cerebellar hemangioblastoma progression and causes a high VHL disease-related pregnancy complication rate. We recommend intensified surveillance of patients with VHL disease, especially of cerebellar hemangioblastomas during preconception care and pregnancy