Asunto(s)

RESUMEN

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. Specific tests should be ordered on the basis of the individual patient's assessment and medical history. Nurses are an important link in the collection of patients' medical history and in assessment as well as in the interpretation of patients' laboratory results. A knowledge of diagnostic tests commonly used in the care of patients with ischemic heart disease is imperative if patients are to receive appropriate, timely, cost-effective care.

Asunto(s)

RESUMEN

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. The T m of >90% of the sequences was predicted within 5 K; 98% of the predicted T ms differ by not more than 10 K from the experimentally determined T m.

Asunto(s)

RESUMEN

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. The application of CL and DL by means of examples is described.

Asunto(s)

RESUMEN

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. Transient changes appeared from the start of shock wave administration; bright signals were seen in liver vessels for several hundred microseconds before they were flushed away with the blood flow. Stationary changes appeared later, increased in intensity over several hundred shock waves and persisted for minutes after cessation of shock wave administration. Both types of signals were interpreted as direct evidence that lithotripter shock waves generated cavitation in vivo. Similar signals were received in the partly degassed water of the lithotripter tub. At autopsy of the piglets, focal intralobular haemorrhages and thrombi of portal veins were detected in the shock wave path. The occurrence of cavitation and tissue damage in the same gross area suggests that cavitation might be involved in the generation of tissue damage by shock waves.

Asunto(s)

RESUMEN

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. Numerical simulation again reveals good quantitative agreement between the model predictions and laboratory data. Finally, the model is extended to give a preliminary description of the dynamics of helminth-host interactions of medical and ecological significance in the real world.

Asunto(s)

Asunto(s)

RESUMEN

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.

Asunto(s)

Asunto(s)

RESUMEN

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. In a more sophisticated system we will find as well either steady state or oscillatory solutions. We determine the role of the parameters with respect to stability and frequency. The most general case will be treated by means of the concept of Lyapunov exponents.

Asunto(s)

RESUMEN

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. Using the method of generalized Ginzburg-Landau equations introduced earlier we then analyze the nonlinear equations. As we are mainly interested in spatial pattern formation on a sphere we consider the problem under an appropriate constraint. Combining the two occurring solutions we find patterns well-known in biology, such as a gradient system and temporal oscillations.

Asunto(s)