Temperature fluctuations in the lower limbs of young and elderly individuals during activities of daily living.

Age-related deficiencies in thermoregulation diminish the capacity to defend against heat loss under conditions often encountered during activities of daily living (ADL). A potential consequence of these deficiencies is that elderly individuals could have colder lower limbs, which would exacerbate the age-related decline in plantarflexor contractile properties and compromise recovery from a tripping incident. Moreover, a common self-perception among the elderly is that their limbs are cold. However, this impression has never been documented, especially under ADL conditions. Our objective was to test the hypothesis that elderly individuals have lower plantarflexor temperatures than their younger counterparts. Skin temperatures above the plantarflexors of elderly and young individuals were continuously recorded during ADL in the winter months and compared under three conditions: quiescent indoor temperature, during a cold challenge, and the recovery period subsequent to the cold challenge. For quiescent indoor periods, differences in skin temperature between the two groups were not statistically significant. During cold exposures, both age and exposure duration were statistically significant factors related to the decrease in skin temperature, with the elderly group maintaining warmer temperatures. In the recovery period following short duration cold exposures, a statistically significant difference between the two groups for the decrease in skin temperature persisted for the first 9min of recovery. The results do not support the hypothesis that the lower limbs of elderly participants are colder. Higher limb temperatures observed in elderly participants were consistent with previous studies of age-related thermoregulatory changes, indicating that deficiencies in vasoconstriction are persistent in ADL.

Indirect foot-and-mouth disease vaccine potency testing based on a serological alternative.

Foot-and-mouth disease (FMD) vaccine potency testing has historically been performed by experimentally infecting vaccinated cattle. A few alternative approaches to the in vivo challenge test based on the correlation between serum titres of primo-vaccinated cattle and protection against infection have been proposed, but none have been accepted by the European Pharmacopoeia (Ph.Eur.) due to the lack of statistical power and the pooling of data over time. The present study addresses these issues and presents data of 150 cattle vaccinated according to Ph.Eur. standards. Four laboratories took part in the serological testing and different serological assays were used, including virus neutralisation assays and ELISA formats. Models correlating specific anti-FMD virus antibody titres to protection were built using logistic regression followed by Receiver Operating Characteristic (ROC) analysis. The best models accurately predicted the in vivo protection status in 80.0% of the cases. Although differences were observed between laboratories and assays used, the majority of antibody pass-levels, determined using ROC analysis, corresponded to at least 75.0% probability of protection. The indirect potency assessment procedure proposed is at least as precise (repeatability=65.8%, reproducibility=60.7%) as the in vivo test, can be standardised and results in a quantitative PD50 value. The validity of the procedure was also demonstrated.

Detection and estimation of avian infectious bronchitis virus antigen by a novel indirect liquid-phase blocking enzyme-linked immunosorbent assay using chicken and rabbit affinity purified immunoglobulins.

An indirect liquid-phase blocking (LPB) enzyme-linked immunosorbent assay (ELISA) using chicken and rabbit affinity purified immunoglobulin G (IgG) has been developed to detect and estimate avian infectious bronchitis virus (IBV) antigen concentration directly in infected allantoic fluid. The method is based on the principle of binding of specific IgG to the test IBV antigen and the assay of unbound IgG on an antigen-coated ELISA plate. The immunoglobulins are chicken N-terminal S2 peplomeric protein-specific IgG isolated by immunoaffinity chromatography on synthetic peptide coupled to CNBr-activated Sepharose 4B or rabbit polyclonal IgG purified from the serum using Protein A Sepharose 4B. The assay detected all tested IBV strains and field isolates propagated in chicken embryos. Signal to noise ratios were calculated from LPB ELISA absorbance units and a diagnostic threshold was established from the signal to noise ratio frequency distribution of samples positive or negative for IBV by virus titration or reverse transcription polymerase chain reaction. The relative sensitivity of the test ranged between 10(5) and 10(6) median egg infectious doses (EID(50)) for chicken IgG and between 10(3) and 10(4) EID(50) for rabbit IgG, depending on the test strain. The assay is simple and takes less than 3 h to perform. It does not require expensive reagents and can be readily adapted to monitor the IBV antigen concentration in allantoic fluids during propagation of vaccine strains or in samples of freeze-dried, live-attenuated IBV vaccines.