Rapid turnover of the recirculating lymphocyte pool in vivo

Lymphocytes are unique among blood cells in their capacity to continually recirculate between blood and the tissues via the lymph. Previous estimates of lymphocyte lifespan in vivo and the turnover of the recirculating lymphocyte pool have been deduced from indirect labeling techniques. Using the fluorescent dye PKH-26, individual labeled cells have been tracked in sheep for periods >2 months. By direct measurement their lifespan was calculated. This label was found to be stable in vivo, allowing long-term analysis of the characteristics of the recirculating lymphocyte pool. It Is possible to calculate the rate of turnover of cells of the recirculating pool based on the rate at which labeled cells disappear from the lymphatic circulation. The recirculating lymphocyte pool was found to repopulate itself every 16.5 ± 3.0 days. Using this label, it was estimated that recirculating lymphocytes divide on average once every 29.8 ± 6.8 days. Labeled erythrocytes were also examined and found to have an average lifespan of 153 days, demonstrating no dye loss over the 2 month period of observation. These data suggest that the recirculating lymphocyte pool is a highly dynamic compartment, with a high rate of turnover and peripheral cell division in vivo. This is the first report of the direct measurement of the in vivo turnover of recirculating lymphocyte pools, and this method may now be used to further analyze the lifespan of individual lymphocyte subsets and the in vivo lifespan of other cell types in viv

Tracking dendritic cells: use of an in situ method to label all blood leukocytes

Here we describe an in situ procedure with a labeling index (percent of labeled blood leukocytes) >98%, which is high enough to permit the direct tracking of dendritic cell (DC) precursors from blood into lymphoid tissues, while circumventing the pitfalls associated with in vitro labeling. DC and lymphocytes have similar blood to afferent lymph migratory capabilities. This method has additional applications in tracking other rare cell populations in both normal and pathological state

Medicine dosing by weight in the home: Can parents accurately weigh preschool children? A method comparison study

Objective: To determine the accuracy with which parents can estimate preschool children's weight using home scales in order to calculate antipyretic dose. Design: Cross-sectional, method comparison study. Setting and participants: 156 preschool children aged 6 months to 6 years recruited from primary care and the community to an antipyretic strategies trial and managed at home. Comparison and outcome measures: Research nurse weight estimate using Seca 835-2 digital paediatric scales compared with parental weight estimate using usual home scales. Results: Parents of 62 (40%) preschool children had home scales. Research scale estimated weights were heavier than home scale weight estimates, with a mean difference of 0.41 kg (95% CI -0.24 to 0.74 kg), with 95% limits of agreement of -2.44 to 1.47 kg. Conclusion: Weight can be estimated accurately enough to calculate antipyretic medicine doses by the minority of parents having scales that can be used to estimate their child's weight

Paracetamol plus ibuprofen for the treatment of fever in children (PITCH): randomised controlled trial

Objective To investigate whether paracetamol (acetaminophen) plus ibuprofen are superior to either drug alone for increasing time without fever and the relief of fever associated discomfort in febrile children managed at home

Identifying the genetic basis of antigenic change in influenza A(H1N1)

Determining phenotype from genetic data is a fundamental challenge. Influenza A viruses undergo rapid antigenic drift and identification of emerging antigenic variants is critical to the vaccine selection process. Using former seasonal influenza A(H1N1) viruses, hemagglutinin sequence and corresponding antigenic data were analyzed in combination with 3-D structural information. We attributed variation in hemagglutination inhibition to individual amino acid substitutions and quantified their antigenic impact, validating a subset experimentally using reverse genetics. Substitutions identified as low-impact were shown to be a critical component of influenza antigenic evolution and by including these, as well as the high-impact substitutions often focused on, the accuracy of predicting antigenic phenotypes of emerging viruses from genotype was doubled. The ability to quantify the phenotypic impact of specific amino acid substitutions should help refine techniques that predict the fitness and evolutionary success of variant viruses, leading to stronger theoretical foundations for selection of candidate vaccine viruses

Phased Array Feed Calibration, Beamforming and Imaging

Phased array feeds (PAFs) for reflector antennas offer the potential for increased reflector field of view and faster survey speeds. To address some of the development challenges that remain for scientifically useful PAFs, including calibration and beamforming algorithms, sensitivity optimization, and demonstration of wide field of view imaging, we report experimental results from a 19 element room temperature L-band PAF mounted on the Green Bank 20-Meter Telescope. Formed beams achieved an aperture efficiency of 69% and system noise temperature of 66 K. Radio camera images of several sky regions are presented. We investigate the noise performance and sensitivity of the system as a function of elevation angle with statistically optimal beamforming and demonstrate cancelation of radio frequency interference sources with adaptive spatial filtering.Comment: 19 pages, 13 figure

The frequency distribution of presenting symptoms in children aged six months to six years to primary care.

Primary care providers and researchers wishing to estimate study recruitment rates need estimates of illness frequency in primary care. Previous studies of children's symptoms have found that presentations are most common for the symptoms: cough, fever, earache, rash, diarrhoea and vomiting. Since 2000, primary care provision in the United Kingdom has changed with the introduction of Walk-in-Centres (WICs) and new Out of Hours (OoHs) providers. To describe the type and frequency of parent-reported presenting symptoms at a range of primary care sites between 2005 and 2007. Parent-reported presenting symptoms, recorded in their own words, were extracted from data collected from all children aged six months to six years during recruitment to a randomised controlled trial. Presenting symptoms were coded and presented as frequency per 100 'consulting sessions' by type of primary care site. Results were evaluated from 2491 episodes of illness at 35 sites. When grouped by primary care site, respiratory symptoms were the most common at OoHs centres, the WIC and general practitioner (GP) surgeries. Trauma symptoms were common in the Emergency Department, but unexpectedly, diarrhoea and vomiting were more common in the Emergency Department and skin presenting symptoms more common at the WIC than at GP sites. We report the relative frequency of acute symptoms by type of primary care provider. These data may be useful to those planning recruitment to primary care paediatric studies and policy makers for planning primary care service provision