The rearing and maintenance of breeding chickens in isolators: 2. Plastic tent isolators

Plastic tent isolators for the rearing and maintenance of chickens from day-old to 80 weeks of age free from a number of pathogens have been evaluated. The use of individual ventilation units for each isolator has been compared with a central plant capable of supplying several isolators and has been found to be more efficient and have lower running costs.     

The installation of high-field NMR equipment in a hospital environment

Installing high-field magnets in hospital environments has implications for safety, for the performance of the equipment and for the well-being of the subjects who will be examined. This paper outlines the relevant properties of magnets and identifies the requirements necessary for a safe and usable installation. One approach to the meeting of these requirements is described.     

A compact mock circulation loop for the in vitro testing of cardiovascular devices

In vitro cardiovascular device performance evaluation in a mock circulation loop (MCL) is a necessary step prior to in vivo testing. A MCL that accurately represents the physiology of the cardiovascular system accelerates the assessment of the device's ability to treat pathological conditions. To serve this purpose, a compact MCL measuring 600 × 600 × 600 mm (L × W × H) was constructed in conjunction with a computer mathematical simulation. This approach allowed the effective selection of physical loop characteristics, such as pneumatic drive parameters, to create pressure and flow, and pipe dimensions to replicate the resistance, compliance, and fluid inertia of the native cardiovascular system. The resulting five-element MCL reproduced the physiological hemodynamics of a healthy and failing heart by altering ventricle contractility, vascular resistance/compliance, heart rate, and vascular volume. The effects of interpatient anatomical variability, such as septal defects and valvular disease, were also assessed. Cardiovascular hemodynamic pressures (arterial, venous, atrial, ventricular), flows (systemic, bronchial, pulmonary), and volumes (ventricular, stroke) were analyzed in real time. The objective of this study is to describe the developmental stages of the compact MCL and demonstrate its value as a research tool for the accelerated development of cardiovascular devices.     

Is rheumatoid factor useful in primary care? A retrospective cross-sectional study

Rheumatoid factor (RF) is frequently tested in general practice where its utility as a diagnostic test for rheumatoid arthritis (RA) is not known. We undertook a retrospective cross-sectioal study to determine the utility and cost of RF in a primary care population. We compared RF with recorded clinical features based on the American College of Rheumatology (ACR) criteria as a diagnostic test for RA in 235 patients in general practice using receiver operating characteristic curves and calculated the cost of testing per case of RA. We analysed 36,191 RF requests made to one laboratory from 2003–2009 at a mean annual cost of £58,164 and the variation and annual cost of RF testing between 77 practices. The sensitivity and specificity of RF at the optimal cut-off value of 20 U/ml were 0.6 and 0.96 and that of two documented clinical ACR criteria were 0.9 and 0.92, respectively. No ACR criteria were documented in 150 (63.8 %) patients who had RF tested. The overall cost of RF testing per case of seropositive RA was £708.75. Of all RF requests, 66.6 % was made by GPs, 7.0 % by rheumatologists and 26.4 % by other hospital departments. The proportion of positive tests was 5.8 % in primary care and 17.7 % in rheumatology. The mean number of tests performed annually in primary care was 4.65 (SD 2.7) per 1,000 patients. RF is less sensitive for RA than clinical features in primary care and is frequently requested in cases without clinical evidence of the disease, adding to the overall cost.