49 research outputs found

    Experimental Design for Variable Selection in data bases

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    This paper analyses the influence of 13 stylized facts of the German economy on the West German business cycles from 1955 to 1994. The method used in this investigation is Statistical Experimental Design with orthogonal factors. We are looking for all existing Plackett-Burman designs realizable by coded observations of these data. The plans are then analysed by regression with forward selection and various classification methods to extract the relevant variables for separating upswing and downswing of the cycles. The results are compared with already existing studies on this topic. --

    DNA methylation profiling to predict recurrence risk in meningioma: development and validation of a nomogram to optimize clinical management

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    Abstract Background Variability in standard-of-care classifications precludes accurate predictions of early tumor recurrence for individual patients with meningioma, limiting the appropriate selection of patients who would benefit from adjuvant radiotherapy to delay recurrence. We aimed to develop an individualized prediction model of early recurrence risk combining clinical and molecular factors in meningioma. Methods DNA methylation profiles of clinically annotated tumor samples across multiple institutions were used to develop a methylome model of 5-year recurrence-free survival (RFS). Subsequently, a 5-year meningioma recurrence score was generated using a nomogram that integrated the methylome model with established prognostic clinical factors. Performance of both models was evaluated and compared with standard-of-care models using multiple independent cohorts. Results The methylome-based predictor of 5-year RFS performed favorably compared with a grade-based predictor when tested using the 3 validation cohorts (ΔAUC = 0.10, 95% CI: 0.03–0.018) and was independently associated with RFS after adjusting for histopathologic grade, extent of resection, and burden of copy number alterations (hazard ratio 3.6, 95% CI: 1.8–7.2, P &lt; 0.001). A nomogram combining the methylome predictor with clinical factors demonstrated greater discrimination than a nomogram using clinical factors alone in 2 independent validation cohorts (ΔAUC = 0.25, 95% CI: 0.22–0.27) and resulted in 2 groups with distinct recurrence patterns (hazard ratio 7.7, 95% CI: 5.3–11.1, P &lt; 0.001) with clinical implications. Conclusions The models developed and validated in this study provide important prognostic information not captured by previously established clinical and molecular factors which could be used to individualize decisions regarding postoperative therapeutic interventions, in particular whether to treat patients with adjuvant radiotherapy versus observation alone. </jats:sec

    Correlation of structure and properties in the silver-ion conducting systems AgI-AgMxOy (M=P,Cr,Mo)

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    Silberiodid-Silberoxisalz-Verbindungen des Typs AgI-AgMxOy (M=V, Nb, Ta, Cr, Mo, W,.....B, Ge, P, As, S, Se, Te) sind sowohl als Keramiken als auch als Gläser wegen ihrer hohen Ionenleitfähigkeit bei vergleichsweise überschaubarer Elektrochemie wichtige Modellsubstanzen für die Untersuchung von Transporteigenschaften in silberionenleitenden Festelektrolyten. Die Transportpfade für bewegliche Ionen in Festelektrolyten lassen sich mit Hilfe von Bindungslängen- Bindungsstärken-Beziehungen als Valenzsummendarstellungen abschätzen. Zwar sind die Phasendiagramme zahlreicher Silberiodid-Silberoxisalz-Systeme bekannt, aber bisher sind nur drei der bis jetzt bekannten kristallinen Phasen strukturell untersucht worden. Dadurch bleibt ein wesentlicher Zugang zum Verständnis der Struktur-Leitfähigkeitskorrelationen nahezu ungenutzt. Ziel dieser Arbeit war daher in den Systemen AgI-AgMxOy (M=P, Cr, Mo) systematische Untersuchungen zur Synthese und strukturellen Charakterisierung der kristallinen Phasen durchzuführen.Anhand der strukturbestimmten Phasen läßt sich anschließend die Verwendbarkeit von Valenzsummendarstellungen für die Voraussage von Leitfähigkeitspfaden in diesen Systemen überprüfen. Ebenso ließ sich dadurch der Einfluß der Gegenionen auf die Beweglichkeit der Silberionen näher bestimmen. Im Gegensatz zur bislang vorherrschenden Ansicht kann die Leitfähigkeit der kristallinen Phasen nur erklärt werden, wenn auch Silberionen auf Plätzen mit gemischter Koordination zur Leitfähigkeit beitragen

    A case report of pseudo-progression after pembrolizumab in metastatic gastric cancer and a review of immunotherapy in gastroesophageal tumors

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    In this report, we present the medical history of a 30-year-old male patient with HER2- and PD-L1-negative metastasized adenocarcinoma of the gastric cardia, who received three cycles of pembrolizumab (200mg every 2 weeks) after the failure of the first-line (1L) treatment with docetaxel, cisplatin, 5fluorouracil (DCF). A restaging computed tomography (CT) scan for the chest and abdomen revealed an apparent progressive disease; therefore, the treatment was terminated. Five months after the termination of the treatment, a new CT scan demonstrated a spontaneous treatment response although no treatment was given during this time period, indicating pseudo-progression of the tumor in the first restaging after three cycles of pembrolizumab. This finding is apparently due to the long-term sustainable immunological effects of pembrolizumab. The current report will present this rare case in more detail and summarize the closed and ongoing clinical trials of immunotherapy drugs in gastroesophageal cancer.(VLID)365613

    Spatio-Temporal Simulation of First Pass Drug Perfusion in the Liver

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    The liver is the central organ for detoxification of xenobiotics in the body. In pharmacokinetic modeling, hepatic metabolization capacity is typically quantified as hepatic clearance computed as degradation in well-stirred compartments. This is an accurate mechanistic description once a quasi-equilibrium between blood and surrounding tissue is established. However, this model structure cannot be used to simulate spatio-temporal distribution during the first instants after drug injection. In this paper, we introduce a new spatially resolved model to simulate first pass perfusion of compounds within the naive liver. The model is based on vascular structures obtained from computed tomography as well as physiologically based mass transfer descriptions obtained from pharmacokinetic modeling. The physiological architecture of hepatic tissue in our model is governed by both vascular geometry and the composition of the connecting hepatic tissue. In particular, we here consider locally distributed mass flow in liver tissue instead of considering well-stirred compartments. Experimentally, the model structure corresponds to an isolated perfused liver and provides an ideal platform to address first pass effects and questions of hepatic heterogeneity. The model was evaluated for three exemplary compounds covering key aspects of perfusion, distribution and metabolization within the liver. As pathophysiological states we considered the influence of steatosis and carbon tetrachloride-induced liver necrosis on total hepatic distribution and metabolic capacity. Notably, we found that our computational predictions are in qualitative agreement with previously published experimental data. The simulation results provide an unprecedented level of detail in compound concentration profiles during first pass perfusion, both spatio-temporally in liver tissue itself and temporally in the outflowing blood. We expect our model to be the foundation of further spatially resolved models of the liver in the future
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