Local regression: a new approach for measurement system comparison analysis.

A new graphical approach for analysis of measurement system comparison studies is proposed. Unlike the established linear regression and Bland-Altman analysis, it does not depend on the assumption of a linear relationship. We review the established analysis approaches and propose a difference plot with non-parametric regression as an adequate tool to describe the relationship between two measurement systems.

Statistical methods for monitoring the relationship between the IFCC reference measurement procedure for hemoglobin A1c and the designated comparison methods in the United States, Japan, and Sweden.

Background: The American Diabetes Association (ADA)/European Association for the Study of Diabetes (EASD)/International Diabetes Federation (IDF)/IFCC Consensus Statement on the worldwide standardization of HbA(1c) states that "...

Uncertainty calculation for calibrators and controls of laboratory diagnostic assays.

The uncertainty of the results from calibrators and controls is an important component of the overall uncertainty of the results of medical samples. The purpose of this note is to review procedures of standardization and to describe the respective calculation of the uncertainty components for calibrators and controls of commercial routine diagnostic assays. The authors hope that the laying out of the procedures for uncertainty calculation of routine calibrators and controls contributes (i) to the transparency on how this component of uncertainty is derived and (ii) to a better understanding and use of the uncertainty concept in the routine laboratory.

Shifting paradigms. Teaching gerontological nursing from a new perspective.

Gerontological health care is undergoing a revolution, much like that of the feminist movement of the 1960s. Fundamental changes in health care require revisions in nursing education to ensure appropriate care of older adults in the least restrictive environment. The purpose of this study is to promote the preparation of future nurses who have the knowledge and the skills necessary to provide nursing care for the growing cohorts of older adults.

Use of measurements of myoglobin and cardiac troponins in the diagnosis of acute myocardial infarction.

Research indicates that no tests of a single cardiac marker are 100% specific and sensitive for diagnosis of AMI in all patients. Each biomarker has advantages and disadvantages (see Table). Over-reliance on a single diagnostic test is risky.

Critical level and detection limit: performance measures for PCR-based assays.

In clinical diagnostic work, sensitivity and specificity are key assay features. In this note we introduce two clinically relevant statistical assay performance measures, the critical level (CL), and the detection limit (DL) for the PCR-based assay. To allow for easy access to these characteristics a Windows-based program has been developed.

A formula for thermal stability (Tm) prediction of PNA/DNA duplexes.

An empirical formula for thermal stability (T m) prediction of PNA/DNA duplexes has been derived. The model is based on the T m as calculated for the corresponding DNA/DNA duplex employing a nearest neighbour approach, by including terms for the pyrimidine content and length of the PNA to take into account the increased thermostability of PNA/DNA hybrids and the asymmetry of the PNA-DNA heteroduplex. The predictive power of the T m prediction formula was challenged with an independent data set not used for model building.

Biological effects of shock waves: cavitation by shock waves in piglet liver.

Shock waves are known to generate cavitation in vitro. In vivo, extracorporeal shock waves may cause haemorrhages in tissues. Two types of changes were detected by conventional, real-time B-scan ultrasound when shock waves were administered to 5 piglet livers in vivo: transient changes consisting of bright signals in intrahepatic branches of the portal vein and tributaries of the hepatic vein, presumed to originate from gas bubbles, and stationary changes consisting of brightening of the area along the long axis of the high pressure field, presumed to indicate an increased number of gas-filled bubbles in this area.

The population dynamics of acquired immunity to helminth infection: experimental and natural transmission.

Recently we described a mathematical model of the role of acquired immunity in host-helminth interactions. The model gives a good quantitative description of the results of experiments involving the nematode Heligmosomoides polygyrus in laboratory mice. Here we apply the model to the results of two further laboratory studies of the same parasite-host interaction: (i) the repeated experimental infection of a genetically heterogeneous host population, and (ii) the natural transmission of the parasite within mouse populations under different dietary conditions.

The population dynamics of acquired immunity to helminth infection.

Based on experimental evidence we develop and exploit a mathematical model to describe the role of acquired immunity in host-helminth interactions. We show that the model gives a quantitative description of the population dynamics in a laboratory situation involving a host immunological response. We make practical predictions based on these results.

On the dynamics of a simple biochemical control circuit.

The quantitative dynamics of a biochemical control circuit that regulates enzyme or protein synthesis by end-product feedback is analyzed. We first study a simplified repressible system, which is known to exhibit either a steady state or an oscillatory solution. By showing the analogy of this n-dimensional system with a time-delay equation for a single variable the mechanism of the self-sustained oscillations becomes transparent.

Pattern formation in morphogenesis. Analytical treatment of the Gierer-Meinhardt model on a sphere.

We first treat the Gierer-Meinhardt equations by linear stability analysis to determine the critical parameter, at which the homogeneous distributions of activator and inhibitor concentrations become unstable. We find two types of instabilities: one leading to spatial pattern formation and another one leading to temporal oscillations. We consider the case where two instabilities are present.