187 research outputs found

    Thermal analysis of a pm sm using fea and lumped parameter modeling

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    Permanent magnet synchronous motors are often used in hybrid electric vehicles due to the high power density. Overheating in a PMSM motor can cause negative effects on the work of permanent magnets and a significant shortening of the life of the machine due to the phenomenon of the thermal ageing of insulation. Therefore, it is extremely important to know the exact temperature distribution in different parts of the electrical machine under various operating conditions. This paper presents a lumped parameter thermal model and FE model of a permanent magnet synchronous motor. A method for the homogenization of a stator winding is also described. In order to validate the accuracy of the calculation results, measurements on the physical model of the machine were carried out

    High resolution computed tomography and pulmonary function in common variable immunodeficiency

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    SummaryPatients with common variable immunodeficiency (CVID) have impaired production of immunoglobulins and hence recurrent airway infections, which in turn may lead to radiological changes and impaired lung function. Uncertainty exists about the nature and frequency of the radiological and the physiological abnormalities, and how they relate to each other. We reassessed high resolution computed tomography (HRCT) images in 65 patients, reported results from previously measured lung function tests, and studied relations between radiology, function and clinical variables. Airway obstruction, ventilatory restriction and impaired gas diffusion was found in 40, 34 and 21% of the patients, respectively. HRCT abnormalities were present in 94% of the subjects, mild changes being the most common. Bronchial wall thickening, found in two thirds of the patients, was related to airway obstruction and impaired gas diffusion. Linear and/or irregular opacities, the most frequent interstitial abnormality, was related to impaired gas diffusion. Bronchiectasis was found in more than half, but only severe bronchiectasis was related to airway obstruction. Since bronchial wall thickening and linear and/or irregular opacities are both frequent and important determinants of impaired pulmonary function, more attention should be given to these features in the follow up of CVID patients

    Clinical Risk Factors Associated with Late-Onset Invasive Group B Streptococcal Disease: Systematic Review and Meta-analyses.

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    BACKGROUND: Group B streptococcal (GBS) infection remains one of the most significant causes of late-onset sepsis and meningitis (LOGBS) among young infants. However, transmission routes and risk factors for LOGBS are not yet fully understood. METHODS: We conducted systematic reviews on clinical risk factors previously reported in the literature (prematurity, low birth weight [<2500 g], antenatal colonization, multiple-gestation pregnancy, maternal age <20 years, male infant sex, intrapartum fever, prolonged rupture of membranes) and meta-analyses to determine pooled estimates of risk. RESULTS: We included 27 articles, reporting 5315 cases. Prematurity (odds ratio 5.66; 95% confidence interval [4.43-7.22]), low birth weight (6.73; [4.68-9.67]), maternal colonization (2.67; [2.07-3.45]), and multiple-gestation pregnancies (8.01; [5.19-12.38]) were associated with an increased risk of LOGBS. CONCLUSIONS: Prematurity/low birth weight and maternal colonization are major risk factors for LOGBS. Future GBS vaccine studies should try to establish the optimal time for vaccination during pregnancy to protect preterm infants

    QOL-04. Histology, treatment, and extent of pretreatment hydrocephalus are major determents of neurocognitive outcome for survivors of pediatric posterior fossa tumors - report from the German HIT-studies [Abstract]

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    BACKGROUND: Cognitive impairments following pediatric brain tumors are generally attributed to tumor site, surgical intervention, complications as well as to nonsurgical treatment. We investigated impairments for patients with medulloblastoma (MB), ependymoma (EP) and low-grade glioma (LGG) of the cerebellum treated within the German pediatric brain tumor network to compare and rank major determents. PATIENTS+METHODS: Following protocol treatment, 245 patients with MB (n=106), EP (n=32), and cerebellar LGG (n=107, surgery only) were examined 2 + 5 years after diagnosis using the German “Neuropsychological-Basic-Diagnostic” (NBD) tool based on the Cattell-Horn-Carroll model for intelligence. Within this retrospective study, multiple linear regression models were applied. RESULTS: The MB+EP vs. LGG-cohort differed slightly in median age at diagnosis (8.7/6.1 years) and location (cerebellar hemispheres: 8%MB+EP/49.5%LGG), while sex-ratio, grade of resection, extent of pre-operative hydrocephalus were comparable. With smaller median tumor-volume in the MB+EP vs. LGG-cohort (34.1/44.1cm3), ranges broadly overlapped. Median scores of age-appropriate tests were in the lower normal range for all patients for fluid and crystallized intelligence, selective attention, visual-spatial processing (VSP) and verbal short-term memory (median=93-103), but distinctly below for processing speed (PS), and psychomotor speed abilities (PMS) (median=65-84). Higher doses of craniospinal irradiation (>23.4Gy/23.4Gy) resulted in lower scores for most domains for MB-patients compared to LGG-patients (e.g., PS-estimate: >23.4Gy:-27.71, p=0.026/23.4Gy:-9.93, p=0.286). EP-patients (surgery+54Gy local radiation) scored better than LGG-patients except for PS (estimate:-15.65, p=0.111). Impairments were accentuated with higher degrees of hydrocephalus (estimate:-7.64, p=0.103) in patients with incomplete resection (estimate:12.23, p=0.006) for PMS both hands. CONCLUSION: Following age-adapted comprehensive treatment, survivors of a cerebellar tumor show significant impairments of PMS abilities in our trials. Our data suggest that slow growing LGG impair neurocognitive development more than local radiotherapy for ependymoma, while craniospinal irradiation compromises VSP and PS in MB. Initial symptomatic intracranial pressure remains a strong predictor for general neuropsychological impairment

    MEDB-41. Identifying a subgroup of patients with early childhood sonic hedgehog-activated medulloblastoma with unfavorable prognosis after treatment with radiation-sparing regimens including intraventricular methotrexate [Abstract]

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    PURPOSE/METHODS: Clinical and molecular risk factors in 142 patients 3 years] 47% vs 85% [<1 year] vs 84% [1-3 years], p<0.001). No TP53 mutations were detected (n=47). DNA methylation classification identified three subgroups: SHH-1(v12.3) (n=39), SHH-2(v12.3) (n=19), and SHH-3(v12.3) (n=19), with distinct cytogenetic profiles (chromosome 2 gains in SHH-1(v12.3), very few alterations in SHH-2(v12.3), and chromosome 9q losses in SHH-3(v12.3)), age profiles (median age [years] SHH-1(v12.3): 1.7, SHH-2(v12.3): 0.9, SHH-3(v12.3): 3.0, p<0.001), and histological distribution (SHH-2(v12.3): 74% MBEN, SHH-1(v12.3)/SHH-3(v12.3): 77%/79% DMB, p<0.001). PFS was more unfavorable in patients with SHH-3(v12.3)-medulloblastoma (5-year PFS 53% vs 86% [SHH-1(v12.3)] vs 95% [SHH-2(v12.3)], p=0.002), which remained the only risk factor on multivariable Cox regression for PFS. OS was comparable (5-year OS 94% [SHH-3(v12.3)] vs 97% [SHH-1(v12.3)] vs 100% [SHH-2(v12.3)], p=0.6). 8/9 patients with SHH-3(v12.3)-medulloblastoma received radiotherapy at relapse (6 craniospinal, 2 local [1 Gorlin syndrome, 1 BRCA2 germline mutation], 1 no radiotherapy [Gorlin syndrome]). CONCLUSION: We identify patients with an increased risk of relapse when treated with radiation-sparing approaches among children with early childhood SHH-medulloblastoma. If these tumors differ from SHH-3-medulloblastoma typically described in older children remains to be verified. Treatment recommendations need to consider cancer predisposition syndromes

    Local and systemic therapy of recurrent medulloblastomas in children and adolescents: results of the P-HIT-REZ 2005 study

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    SIMPLE SUMMARY: A medulloblastoma recurrence is usually associated with an unfavorable prognosis. The German P-HIT-REZ 2005 Study gathered data from patients with relapsed medulloblastomas treated in different, non-randomized therapy arms dependent on preconditions of the patients (previous treatment, comorbidities, relapse pattern), the decision of treating physicians, and the patients’/parents’ choice. A total of 93 evaluable patients with refractory or relapsed medulloblastoma were enrolled. The main aim of this study was to analyze the impact of patient and disease characteristics as well as local and systemic therapies on post-relapse progression-free (PFS) and overall survival (OS). In multivariate analysis, a short time until the first recurrence (<18 months) was the strongest predictor for a worse PFS and OS, which was mainly associated with molecular subgroup 3. Metastatic disease, at relapse, only had a significant impact on OS. Re-biopsy, at relapse, is highly recommended to investigate the histopathological and molecular genetic tumor characteristics and to exclude a secondary malignancy. ABSTRACT: Recurrent medulloblastomas are associated with survival rates <10%. Adequate multimodal therapy is being discussed as having a major impact on survival. In this study, 93 patients with recurrent medulloblastoma treated in the German P-HIT-REZ 2005 Study were analyzed for survival (PFS, OS) dependent on patient, disease, and treatment characteristics. The median age at the first recurrence was 10.1 years (IQR: 6.9–16.1). Median PFS and OS, at first recurrence, were 7.9 months (CI: 5.7–10.0) and 18.5 months (CI: 13.6–23.5), respectively. Early relapses/progressions (<18 months, n = 30/93) found mainly in molecular subgroup 3 were associated with markedly worse median PFS (HR: 2.34) and OS (HR: 3.26) in regression analyses. A significant survival advantage was found for the use of volume-reducing surgery as well as radiotherapy. Intravenous chemotherapy with carboplatin and etoposide (ivCHT, n = 28/93) showed improved PFS and OS data and the best objective response rate (ORR) was 66.7% compared to oral temozolomide (oCHT, n = 47/93) which was 34.8%. Intraventricular (n = 43) as well as high-dose chemotherapy (n = 17) at first relapse was not related to a significant survival benefit. Although the results are limited due to a non-randomized study design, they may serve as a basis for future treatment decisions in order to improve the patients’ survival

    Second-generation molecular subgrouping of medulloblastoma: an international meta-analysis of Group 3 and Group 4 subtypes

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    In 2012, an international consensus paper reported that medulloblastoma comprises four molecular subgroups (WNT, SHH, Group 3, and Group 4), each associated with distinct genomic features and clinical behavior. Independently, multiple recent reports have defined further intra-subgroup heterogeneity in the form of biologically and clinically relevant subtypes. However, owing to differences in patient cohorts and analytical methods, estimates of subtype number and definition have been inconsistent, especially within Group 3 and Group 4. Herein, we aimed to reconcile the definition of Group 3/Group 4 MB subtypes through the analysis of a series of 1501 medulloblastomas with DNA-methylation profiling data, including 852 with matched transcriptome data. Using multiple complementary bioinformatic approaches, we compared the concordance of subtype calls between published cohorts and analytical methods, including assessments of class-definition confidence and reproducibility. While the lowest complexity solutions continued to support the original consensus subgroups of Group 3 and Group 4, our analysis most strongly supported a definition comprising eight robust Group 3/Group 4 subtypes (types I–VIII). Subtype II was consistently identified across all component studies, while all others were supported by multiple class-definition methods. Regardless of analytical technique, increasing cohort size did not further increase the number of identified Group 3/Group 4 subtypes. Summarizing the molecular and clinico-pathological features of these eight subtypes indicated enrichment of specific driver gene alterations and cytogenetic events amongst subtypes, and identified highly disparate survival outcomes, further supporting their biological and clinical relevance. Collectively, this study provides continued support for consensus Groups 3 and 4 while enabling robust derivation of, and categorical accounting for, the extensive intertumoral heterogeneity within Groups 3 and 4, revealed by recent high-resolution subclassification approaches. Furthermore, these findings provide a basis for application of emerging methods (e.g., proteomics/single-cell approaches) which may additionally inform medulloblastoma subclassification. Outputs from this study will help shape definition of the next generation of medulloblastoma clinical protocols and facilitate the application of enhanced molecularly guided risk stratification to improve outcomes and quality of life for patients and their families

    Identification of low and very high-risk patients with non-WNT/non-SHH medulloblastoma by improved clinico-molecular stratification of the HIT2000 and I-HIT-MED cohorts

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    Molecular groups of medulloblastoma (MB) are well established. Novel risk stratification parameters include Group 3/4 (non-WNT/non-SHH) methylation subgroups I-VIII or whole-chromosomal aberration (WCA) phenotypes. This study investigates the integration of clinical and molecular parameters to improve risk stratification of non-WNT/non-SHH MB. Non-WNT/non-SHH MB from the HIT2000 study and the HIT-MED registries were selected based on availability of DNA-methylation profiling data. MYC or MYCN amplification and WCA of chromosomes 7, 8, and 11 were inferred from methylation array-based copy number profiles. In total, 403 non-WNT/non-SHH MB were identified, 346/403 (86%) had a methylation class family Group 3/4 methylation score (classifier v11b6) ≥ 0.9, and 294/346 (73%) were included in the risk stratification modeling based on Group 3 or 4 score (v11b6) ≥ 0.8 and subgroup I-VIII score (mb_g34) ≥ 0.8. Group 3 MB (5y-PFS, survival estimation ± standard deviation: 41.4 ± 4.6%; 5y-OS: 48.8 ± 5.0%) showed poorer survival compared to Group 4 (5y-PFS: 68.2 ± 3.7%; 5y-OS: 84.8 ± 2.8%). Subgroups II (5y-PFS: 27.6 ± 8.2%) and III (5y-PFS: 37.5 ± 7.9%) showed the poorest and subgroup VI (5y-PFS: 76.6 ± 7.9%), VII (5y-PFS: 75.9 ± 7.2%), and VIII (5y-PFS: 66.6 ± 5.8%) the best survival. Multivariate analysis revealed subgroup in combination with WCA phenotype to best predict risk of progression and death. The integration of clinical (age, M and R status) and molecular (MYC/N, subgroup, WCA phenotype) variables identified a low-risk stratum with a 5y-PFS of 94 ± 5.7 and a very high-risk stratum with a 5y-PFS of 29 ± 6.1%. Validation in an international MB cohort confirmed the combined stratification scheme with 82.1 ± 6.0% 5y-PFS in the low and 47.5 ± 4.1% in very high-risk groups, and outperformed the clinical model. These newly identified clinico-molecular low-risk and very high-risk strata, accounting for 6%, and 21% of non-WNT/non-SHH MB patients, respectively, may improve future treatment stratification
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