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Discrimination Power (discrimination + power)
Selected AbstractsPortosystemic pressure gradient during transjugular intrahepatic portosystemic shunt with Viatorr stent graft: What is the critical low threshold to avoid medically uncontrolled low pressure gradient related complications?JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 1 2008Hwan-Hoon Chung Abstract Background:, Inappropriately decreased portosystemic pressure gradient (PSG) during transjugular intrahepatic portosystemic shunt (TIPS) can cause fatal complications but the critical low threshold of PSG is still not clear. The aim of the present study was to evaluate the critical low threshold of PSG during TIPS. Methods:, Sixty-six patients with cirrhosis who successfully underwent de novo TIPS with Viatorr stent grafts were studied. Medically uncontrolled low pressure gradient (LPR) complication was defined as when a patient died, or when acute transplantation or a TIPS reduction procedure was performed due to refractory encephalopathy or the deterioration of hepatic function within 3 months after the procedure. For the determination of the risk group for medically uncontrolled LPR complications, the Child-Pugh score and the model of end-stage liver disease (MELD) score showing a 100% negative predictive value was decided on as a threshold for each score. The risk group was defined when either of both scores was higher than its threshold. For the determination of a critical low post-TIPS PSG, a value of post-TIPS PSG showing the highest discrimination power on the receiver operating characteristic (ROC) curve in the risk group was decided on as a critical low threshold of PSG. The medically uncontrolled LPR complication rates of the patients with the determined threshold or lower were evaluated for the risk group. Results:, Medically uncontrolled LPR complications developed in nine patients (13.6%). Five patients died and four patients had TIPS reduction procedures. Patients with more than 10 on the Child-Pugh score or more than 14 on the MELD score were determined to be the risk group and 34 patients were included. The critical lower threshold of the post-TIPS PSG showing the highest discrimination power on the ROC curve was 5 mmHg (sensitivity 100%, specificity 72%), and the medically uncontrolled LPR complication rates of the patients with 5 mmHg or lower on the post-TIPS PSG were 56.3% (9/16) in the risk group. Conclusions:, The critical threshold of the post-TIPS PSG to avoid the medically uncontrolled LPR complications of TIPS was >5 mmHg. The PSG should not be reduced below this level in the risk group. [source] Improved performance characteristics of the von Willebrand factor ristocetin cofactor activity assay using a novel automated assay protocolJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 10 2010A. HILLARP Summary.,Background, objectives and methods:,An accurate, sensitive and precise assay for reliable determination of the ristocetin cofactor activity of von Willebrand factor (VWF:RCo) in plasma and von Willebrand Factor (VWF)-containing concentrates has been evaluated. The assay is based on a commercially available automated protocol with modifications including a combination of adding additional ristocetin and the use of two calibration curves for the high and low measuring ranges. Results:,Addition of extra ristocetin resulted in improved measurement of VWF recoveries from various VWF-containing concentrates that were underestimated using the standard automated protocol. The modifications resulted in improved assay performance over an extended measuring range (2.00,0.03 IU mL,1). Accuracy was tested using VWF deficiency plasma spiked with the 1st international standard (IS) for VWF concentrate. Seven dilutions, ranging from 1.80 to 0.05 IU mL,1, were analyzed and resulted in measured concentrations between 80% and 100% of the assigned potency of the standard. Linearity was determined from the regression plot of the same concentrate dilutions and resulted in a correlation coefficient of 0.998. The repeatability, expressed as coefficient of variation, was 2% in the normal range (0.90 IU mL,1) and 8% at the level of 0.05 IU mL,1. The corresponding reproducibility results were 2% and 15% at the normal and low measuring ranges, respectively. Conclusions:,Analysis of patients with von Willebrand disease (VWD) indicates that the modified automated BCS® protocol has a superior discrimination power compared with the standard protocol. This is especially true in samples with low VWF, as in patients with type 3 VWD. [source] Characterization of novel sugarcane expressed sequence tag microsatellites and their comparison with genomic SSRsPLANT BREEDING, Issue 4 2006L. R. Pinto Abstract Microsatellites or simple sequence repeats (SSRs) are one of the most suitable markers for genome analysis as they have great potential to aid breeders to develop new improved sugarcane varieties. The development of SSR derived from expressed sequence tags (EST) opens new opportunities for genetic investigations at a functional level. In the present work, the polymorphism obtained with a subset of 51 EST,SSRs derived from sucest was compared with those generated by 50 genomic SSRs (gSSR) in terms of number of alleles, polymorphism information content, discrimination power and their ability to establish genetic relationships among 18 sugarcane clones including three Saccharum species (S. officinarum, S. barberi, S. sinense). The majority of EST,SSRs loci had four to six alleles in contrast to the seven to nine observed for the gSSRs loci. Approximately, 35% of the gSSRs had PIC values around 0.90 in contrast to 15% of the EST,SSRs. However, the mean discrimination power of the two types of SSR did not differ significantly as much as the average genetic similarity (GS) based on Dice coefficient. The correlation between GS of the two types of SSRs was high (r = 0.71/P = 0.99) and significant. Although differences were observed between dendrograms obtained with each SSR type, both were in good agreement with pedigree information. The S. officinarum clone IJ76-314 was grouped apart from the other clones evaluated. The results here demonstrate that EST,SSRs can be successfully used for genetic relationship analysis, extending the knowledge of genetic diversity of sugarcane to a functional level. [source] Determination of aerobic-anaerobic metabolism-related compounds in a Chaoborus flavicans population by infusion ion trap mass spectrometry of extracts of individual larvaeRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2006Maria da Graça Gama Melão In a daily migration, the aquatic larvae of Chaoborus flavicans (a phantom midge) alternate oxygen-saturated and anoxic lake strata. To investigate this cycle, larvae were collected at a natural environment, and acetate, propionate, pyruvate, lactate, glycerol, phosphate, maleate, succinate, glucose and citrate were determined. Each larva was homogenized with 200,µL water and deproteinized with a spin-filter; 50,µL aliquots were mixed with 50,µL of a buffer containing 80,mM propylamine, 20,mM HCl and 0.06,mM 2,4-dihydroxybenzoic acid (internal standard) in methanol. The extracts were infused in an electrospray ionization ion-trap mass spectrometer. The limits of detection for the [M,H], peaks ranged from 2,µM for pyruvate and lactate to 200,µM for acetate and glycerol. The MS2 ion-trap spectra obtained at pH 7 (ammonium acetate buffer) were used to distinguish maleate (cis -2-butenedioic), which gave [M,CO2,H], (m/z 71), from fumarate (trans -2-butenedioic), which showed first a loss of water yielding an instable peak at m/z 97. The compounds involved in the aerobic-anaerobic adjustment of the metabolism were revealed by linear discriminant analysis. Acetate, citrate, glucose, maleate (which decreased during the daytime), and particularly succinate (which increased), showed the maximal discrimination power between the day- and night-time samples. Copyright © 2006 John Wiley & Sons, Ltd. [source] Development and Validation of the Excess Mortality Ratio,adjusted Injury Severity Score Using the International Classification of Diseases 10th EditionACADEMIC EMERGENCY MEDICINE, Issue 5 2009Jaiyong Kim MD Abstract Objectives:, This study aimed to develop and validate a new method for measuring injury severity, the excess mortality ratio,adjusted Injury Severity Score (EMR-ISS), using the International Classification of Diseases 10th Edition (ICD-10). Methods:, An injury severity grade similar to the Abbreviated Injury Scale (AIS) was converted from the ICD-10 codes on the basis of quintiles of the EMR for each ICD-10 code. Like the New Injury Severity Score (NISS), the EMR-ISS was calculated from three maximum severity grades using data from the Korean National Injury Database. The EMR-ISS was then validated using the Hosmer-Lemeshow goodness-of-fit chi-square (HL chi-square, with lower values preferable), the area under the receiver operating characteristic curve (AUC-ROC), and the Pearson correlation coefficient to compare it with the International Classification of Diseases 9th Edition,based Injury Severity Score (ICISS). Nationwide hospital discharge abstract data (DAD) from stratified-sample general hospitals (n = 150) in 2004 were used for an external validation. Results:, The total number of study subjects was 29,282,531, with five subgroups of particular interest identified for further study: traumatic brain injury (TBI, n = 3,768,670), traumatic chest injury (TCI, n = 1,169,828), poisoning (n = 251,565), burns (n = 869,020), and DAD (n = 26,374). The HL chi-square was lower for EMR-ISS than for ICISS in all groups: 42,410.8 versus 55,721.9 in total injury, 7,139.6 versus 20,653.9 in TBI, 6,603.3 versus 4,531.8 in TCI, 2,741.2 versus 9,112.0 in poisoning, 764.4 versus 4,532.1 in burns, and 28.1 versus 49.4 in DAD. The AUC-ROC for death was greater for EMR-ISS than for ICISS: 0.920 versus 0.728 in total injury, 0.907 versus 0.898 in TBI, 0.675 versus 0.799 in TCI, 0.857 versus 0.900 in poisoning, 0.735 versus 0.682 in burns, and 0.850 versus 0.876 in DAD. The Pearson correlation coefficient between the two scores was ,0.68 in total injury, ,0.76 in TBI, ,0.86 in TCI, ,0.69 in poisoning, ,0.58 in burns, and ,0.75 in DAD. Conclusions:, The EMR-ISS showed better calibration and discrimination power for prediction of death than the ICISS in most injury groups. The EMR-ISS appears to be a feasible tool for passive injury surveillance of large data sets, such as insurance data sets or community injury registries containing diagnosis codes. Additional further studies for external validation on prospectively collected data sets should be considered. [source] Application of the Time-Dependent ROC Curves for Prognostic Accuracy with Multiple BiomarkersBIOMETRICS, Issue 1 2006Yingye Zheng Summary The rapid advancement in molecule technology has led to the discovery of many markers that have potential applications in disease diagnosis and prognosis. In a prospective cohort study, information on a panel of biomarkers as well as the disease status for a patient are routinely collected over time. Such information is useful to predict patients' prognosis and select patients for targeted therapy. In this article, we develop procedures for constructing a composite test with optimal discrimination power when there are multiple markers available to assist in prediction and characterize the accuracy of the resulting test by extending the time-dependent receiver operating characteristic (ROC) curve methodology (Heagerty, Lumley, and Pepe, 2000, Biometrics56, 337,344). We employ a modified logistic regression model to derive optimal linear composite scores such that their corresponding ROC curves are maximized at every false positive rate. We provide theoretical justification for using such a model for prognostic accuracy. The proposed method allows for time-varying marker effects and accommodates censored failure time outcome. When the effects of markers are approximately constant over time, we propose a more efficient estimating procedure under such models. We conduct numerical studies to evaluate the performance of the proposed procedures. Our results indicate the proposed methods are both flexible and efficient. We contrast these methods with an application concerning the prognostic accuracies of expression levels of six genes. [source] A food safety control low mass-range proteomics platform for the detection of illicit treatments in veal calves by MALDI-TOF-MS serum profilingBIOTECHNOLOGY JOURNAL, Issue 11 2009Lorenza Della Donna Abstract Performance enhancing agents (PEAs) are illegally used in cattle and other meat producing species to increase food conversion and lean meat production. Due to the very short breeding cycle, veal calves represent the meat producing bovine category mostly subjected to illicit treatments. These chemical agents are difficult to detect by conventional analytical approaches due to the employment of synergistic formulations at very low dosage and given the use of uncharacterized novel compounds. Such a scenario has fostered a strong interest in the discovery of functional molecular biomarkers for the detection of growth promoting agents in meat producing species. A multivariate MALDI-TOF-MS proteomics platform has been developed using bovine serum samples. Analytical performances have been thoroughly evaluated in order to enable reproducible profiles from 10 ,L sera samples. We propose univariate and multivariate discrimination models capable to identify calves undergoing illicit treatments. In particular, we found a strong discrimination power associated with a polypeptide fragment from ,2-glycoprotein-I. We provide a fundamental proof of concept in the potential application of MALDI-TOF-MS proteomics profiling in the food safety control. [source] | |||||||||||||