Independent assessment of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) sample preparation quality: A novel statistical approach for quality scoring.

Preparation of samples according to an optimized method is crucial for accurate determination of polymer sample characteristics by Matrix-Assisted Laser Desorption Ionization (MALDI) analysis. Sample preparation conditions such as matrix choice, cationization agent, deposition technique or even the deposition volume should be chosen to suit the sample of interest. Many sample preparation protocols have been developed and employed, yet finding the optimal sample preparation protocol remains a challenge.

Is there a suitable point-of-care glucose meter for tight glycemic control? Evaluation of one home-use and four hospital-use meters in an intensive care unit.

Background: Implementation of tight glycemic control (TGC) and avoidance of hypoglycemia in intensive care unit (ICU) patients require frequent analysis of blood glucose. This can be achieved by accurate point-of-care (POC) hospital-use glucose meters. In this study one home-use and four different hospital-use POC glucose meters were evaluated in critically ill ICU patients.

Alignment and clustering strategies for GC×GC-MS features using a cylindrical mapping.

Comprehensive two-dimensional gas chromatography coupled to mass spectrometry is a powerful tool to analyze complex samples. For application of the technique in studies like biomarker discovery in which large sets of complex samples have to be analyzed, extensive preprocessing is needed to align the data obtained in several injections (analyses). We developed new alignment and clustering algorithms for this type of data.

Representative drug sampling: sample size calculations revisited.

Calculating the required number of samples to be tested from a consignment of pills suspected of containing drugs can be performed from a Bayesian perspective. Procedures in literature are based on the outstanding work of Aitken. However, in the mathematical treatment of the problem, the limitedness of the consignment is not systematically used.

A statistical approach to assess analytical sensitivity of diagnostic assays in the presence of false-positive results.

Analytical sensitivity is one of the performance characteristics of diagnostic tests. As always, a subtle balance has to be found between sensitivity and specificity, but given the clinical setting and the intended use of the diagnostic system, a less than 100% specificity can be perfectly acceptable. Probit analysis is a wide-spread statistical technique used to assess the concentrations corresponding to pre-set hit rates, but this technique assumes a 100% specificity.

Sensitivity studies for quantitative assays: use of censored data analysis.

Probit regression analysis is frequently used to study the relation between the concentration of an analyte in a sample and the probability that the assay used yields a positive test result. For these analyses only the qualitative classification 'positive' or 'negative' is used, whereas, particularly in the case where the assay is quantitative in nature, the results contain more information. In the current paper, we propose an alternative method, in which the negative test results are treated as being (left) censored.

Stochastic processes defining sensitivity and variability of internally calibrated quantitative NASBA-based viral load assays.

For quantitative assessment of virus particles in patient plasma samples various assays are commercially available. Typical performance characteristics for such assays are sensitivity, precision and the range of linearity. In order to assess these properties it is common practice to divide the range of inputs into subranges in order to apply different statistical models to evaluate these properties separately.

Mathematic modeling of the risk of HBV, HCV, and HIV transmission by window-phase donations not detected by NAT.

Background: Blood transfusion centers around the world have introduced minipool NAT to reduce the risk of HBV, HCV, and HIV transmission by blood donations drawn in the infectious window phase. What would be the reduction in the residual risk when minipool NAT would be replaced by single-donation NAT?

Study Design And Methods: A mathematic model was developed to estimate the probability of virus transmission by blood transfusion when NAT screening methods are used for virologic safety testing. The major assumptions used are threefold: 1) The viral nucleic acid concentrations in the early window phase of infection double in 2.

Principles of quantitation of viral loads using nucleic acid sequence-based amplification in combination with homogeneous detection using molecular beacons.

For quantitative NASBA-based viral load assays using homogeneous detection with molecular beacons, such as the NucliSens EasyQ HIV-1 assay, a quantitation algorithm is required. During the amplification process there is a constant growth in the concentration of amplicons to which the beacon can bind while generating a fluorescence signal. The overall fluorescence curve contains kinetic information on both amplicon formation and beacon binding, but only the former is relevant for quantitation.