7th Drug hypersensitivity meeting: part two

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The selection of microbial communities by constant or fluctuating temperatures

The diversity of bacterial communities isolated from Antarctic lake sediment in chemostats under constant low temperature (8°C) or diurnally fluctuating temperature (1°C to 16°C) was examined. The median optimum temperature for growth of the freshwater bacteria isolated from the fluctuation chemostat was significantly lower (P < 1%) than that for those from the constant temperature chemostat. The diversity of the enriched bacterial community isolated in the chemostat culture subjected to short‐term temperature fluctuations was greater than that enriched under constant temperature. At least 4 different groups of bacteria, that occupied separate ‘temperature niches’, were isolated from the fluctuating chemostat compared to only one group isolated from the stable chemostat. Furthermore, a pseudomonad from the fluctuating chemostat was shown to out‐compete another pseudomonad from the stable chemostat when both were subjected to the fluctuating temperature regime. However, the pseudomonad of constant (8°C) temperature origin out‐competed that isolated under fluctuating conditions when subjected to a stable temperature regime

The effect of pedometer step goal, feedback and self-monitoring interventions on accelerometer-measured physical activity in children

This study assessed the utility of 3-week goal-setting, self-monitoring and step-feedback pedometer interventions for increasing physical activity (PA) in children, and the relative impact of individual and group-standardised goals. Three classes of primary school children (n = 68) were randomised to: (a) individual-standardised goal (IS), (b) group-standardised goal (GS) or (c) open pedometer control (CON) groups. PA was assessed via accelerometry (baseline and end-point). There were no main effects for study group, but there was an interaction between time and group for moderate-to-vigorous PA (MVPA), with MVPA time change differing between IS and CON, as MVPA increased in IS but decreased in CON. Mean plots showed MVPA increased in less-active children allocated IS goals, but decreased in GS children. MVPA in more-active children did not change in IS, but declined in GS and CON. Goal-setting, self-monitoring and step-feedback pedometer interventions did not modify PA. Individual-standardised goals may, however, have utility due to mitigating the decline in MVPA in more-active and increasing MVPA in less-active children

Discrepancies in accelerometer-measured physical activity in children due to cut-point non-equivalence and placement site

This study examined dissonance in physical activity (PA) between two youth-specific hip-derived intensity cut-points for the Actiwatch (AW), and compared PA between hip and wrist placements using site-specific cut-points. Twenty-four children aged 11.2 ± 0.5 years wore the AW on the right hip and non-dominant wrist during a typical school day. Minutes of sedentary behaviour and vigorous activity were greater using Puyau et al. (2002) cut-points, but light, moderate, and moderate-to-vigorous (MVPA) were greater when derived using Puyau et al. (2004) cut-points (P < 0.01). Total hip activity counts were lower than wrist. Sedentary minutes were greater at the hip, but minutes of light, vigorous and MVPA were lower (P < 0.01). Moderate minutes were greater at the hip, but differed only when applying the Puyau et al. (2004) cut-points (P < 0.01). In conclusion, data comparisons between two hip derived AW cut-points and between hip and wrist data are inappropriate. Future researchers using the AW at the hip should present data reduced using both published cut-points. As hip and wrist data differ, the wrist placement is preferable as it will likely increase children's compliance to monitoring protocols due to reduced obtrusiveness compared to the hip

The impact of school-day variation in weight and height on National Child Measurement Programme body mass index-determined weight category in Year 6 children

Background In England, the National Child Measurement Programme (NCMP) annually measures the weight and height of Year 6 schoolchildren (age 10–11 years). While measurement protocols are defined, the time of measurement within the school day is not. This study examined the impact of school-day variation in weight and height on NCMP body mass index (BMI)-determined weight category in Year 6 children. Methods Standing height and weight were measured in morning and afternoon sessions in 74 children, boys (n= 34; height: 141.16 ± 7.45 cm; weight: 36.48 ± 9.46 kg, BMI: 18.19 ± 3.98 kg/m2) and girls (n= 40; height: 144.58 ± 7.66 cm; weight: 42.25 ± 11.29 kg; BMI: 19.97 ± 3.98 kg/m2) aged 11 ± 0.3 years. Results In the whole sample, height decreased (Mean =−0.51 cm, 95% CI: −0.39 to −0.64 cm, P= 0.01), weight did not change (Mdn = 36.40 to 36.35, P= 0.09) and BMI increased (Mdn = 18.04 to 18.13, P= 0.01). In girls weight increased (Mdn = 41.40 to 41.60, P= 0.01). BMI percentile increased (Mdn = 57th to 59.5th centile, P= 0.01). One girl increased in BMI category from morning to afternoon according to the clinical cut-offs (≤2nd, >91st and >98th) and three girls increased BMI category according to the population monitoring cut-offs (≤2nd, ≥85th, ≥95th). Conclusions School-day variation in height (and in girls alone, weight) impact upon increased BMI and BMI percentile in afternoon versus morning measurements in Year 6 children. Although not reaching statistical significance, resultant variation in categorization at the individual level may lead to unwarranted follow-up procedures being initiated. Further research with larger samples is required to further explore the impact of daily variability in height and weight upon both clinical and population monitoring BMI-determined weight status categorization in the NCMP

Intra‐ and Inter‐Instrument Reliability of the Actiwatch 4 Accelerometer in a Mechanical Laboratory Setting

This study aimed to quantify the intra-and inter-instrument reliability of the Actiwatch 4 accelerometer (AW4) in a mechanical setting. Twenty seven AW4 were attached to an isokinetic dynamometer and subjected to angular acceleration for 30 min at 50 deg/sec representing moderate intensity (MPA condition) and 200 deg/sec representing vigorous intensity (VPA condition), with a repeat trial conducted. Reliability was assessed using coefficient of variation (CV), absolute percent error (APE), and intraclass correlation coefficients (ICC). Mean AW4 activity counts displayed acceptable reliability according to CV in both conditions (ConMPA: CVintra = 4.6%, APEintra = 6.6%, CVinter = 6.4%, APEinter = 5.2%; ConVPA: CVintra = 3.9%, APEintra = 5.6%, CVinter = 5.9%, APEinter = 4.7%). When counts were re-categorised into minutes of MPA and VPA, lower CV values were observed (ConMPA: CVintra = 3.2%, APEintra = 4.5%, CVinter = 4.3%, APEinter = 3.2%; ConVPA: CVintra = 0.0%, APEintra = 0.0%, CVinter = 0.0%, APEinter = 0.0%). When activity counts were re-categorised as minutes of MVPA, excellent reliability was observed (CVintra, APEintra, CVinter, and APEinter = 0.0%) in both conditions. Mean AW4 activity counts exhibit reliability statistics comparable to other accelerometers. Reliability is improved when activity counts are re-categorised as time spent in MPA and VPA, with greatest reliability obtained when counts are recategorised as time spent in MVPA. As MVPA is the subcomponent of physical activity most associated with health benefits it would appear that the AW4 is reliable for measuring time spent in this health enhancing intensity category, at least from testing in a mechanical laboratory setting