Estimation of in vitro prebiotic activity of individual and mixed dietary fibres

Background: Epidemiological studies have demonstrated a link between dietary fibre deficiency and prevalence of many “Western diseases” particularly colon related diseases. Many of the health benefits associated with dietary fibre are attributed to their prebiotic effect. However, not all fibres have the same prebiotic potential or the same impact on colon health.

Objective: To examine the in vitro fermentation properties of individual and mixed dietary fibres by measuring fermentation byproducts over time.

Design: Wheat bran and guar gum were selected for this study. Individual and mixed dietary fibres were added to batch fermentation system and were inoculated with fresh faecal inoculum (n= 4). Positive (inulin) and negative (no substrate) fermenters were also used to determine the differences. The pH of the five fermenters was adjusted to a baseline of 5.5 and 6.8 representing the pH of the proximal and distal sections of the colon respectively. Samples were drawn out of the fermenters at 0, 3, 9 and 24 hours for the analysis of pH, ammonia and short chain fatty acids (SCFAs).

Outcomes: There were no significant differences in the pH levels at various time points between fermenters adjusted to pH 5.5 at baseline. However, in fermenters adjusted to pH 6.8 the pH of the fermenter containing wheat bran increased over the time (24h (P = 0.017)) due to production of a high amount of ammonia. The total SCFAs production was greater in fermenters containing combined fibres.

Conclusion: There is a large inter-individual variation in the prebiotic effect of all types of dietary fibres, however, in the present study, dietary fibre combinations showed greater prebiotic potential compared with the individual fibres.

Manage one beach or two? Movements and space-use of the threatened hooded plover (Thinornis rubricollis) in south-eastern Australia

An understanding of space use and dispersal of a wildlife species is essential for effective management. We examined the movements of a beach-dwelling, threatened population of hooded plover (Thinornis rubricollis) in southern central Victoria, Australia, by analysing sightings of colour-banded birds (4897 sightings; 194 birds tracked for up to 9 years). Most movements were relatively short (5050 ± 305 m), with 61.4% <1 km and 95.3% <20 km; they lacked directional or sexual bias. The extent of coastline used by individual birds was 47.8 ± 58.0 km. Regional differences in average distances moved by adults were apparent. For adults, movement rates (mean distance per day) were higher during the non-breeding season than during the breeding season. Non-breeding adults generally remained close to their partners (non-breeding, 456.3 ± 163.9 m; breeding, 148.2 ± 45.3 m). Largest flock sizes were recorded during the non-breeding period, and flocking was not uniformly distributed along the coast but appeared to be concentrated in particular locations. The frequency of pair cohesion (i.e. when the distance between partners was zero on a given day) was similar during the breeding (69.6%) and non-breeding seasons (67.7%). Breeding territories (kernel analysis) were 36.7 ± 5.7 ha and overlapped from year to year in all cases (23 pairwise comparisons; 47.9 ± 7.1% overlap). The high fidelity and constancy of territories confirms they warrant ongoing management investment, although the species relies on a matrix of breeding and non-breeding sites. The latter appear to occur in specific parts of the coast and warrant enhanced protection and more research attention. Fragmentation of the breeding population might occur where habitat is rendered unsuitable for > ~50 km.

Studies of the human lymphocyte P2Z receptor and its activation of phospholipase D

Extracellular adenosine 5′-triphosphate (ATP) is an agonist for the P2Z receptor of human leukaemic lymphocytes and opens a Ca ²⁺-selective ion channel, which also conducts Ba²⁺, Sr²⁺ and the small fluorescent dye, ethidium⁺. A wide range of receptor agonists, many of which raise cytosolic [Ca²⁺] activate phospholipase D (PLD). In the present study, it was shown that both ATP and 3′-O-(4-benzoylbenzoyl)-ATP (BzATP) stimulated PLD activity in a concentration-dependent manner, and the inhibitory effects of suramin, oxidised ATP, extracellular Na⁺ and Mg²⁺ suggested that the effect of these agonists is mediated by P2Z receptors. The role of divalent cations in ATP-stimulated PLD activity was investigated. Several agonists (eg ATP, thapsigargin, ionomycin) stimulated a rise in cytosolic [Ca²⁺] in human lymphocytes, but only ATP and ionomycin stimulated PLD activity. When Ca²⁺ influx was prevented by EGTA, the majority of ATP-stimulated and all of ionomycin-stimulated PLD activity was inhibited. Preloading cells with the Ca²⁺ chelator, BAPTA, reduced cytosolic [Ca²⁺] and, paradoxically, ATP-stimulated PLD activity was potentiated. ATP-stimulated PLD activity was supported by both Ba²⁺ and Sr²⁺ when they were substituted for extracellular Ca²⁺. Furthermore, both ATP-stimulated PLD activity and ATP-stimulated ¹³³Ba²⁺ influx showed a linear dependence on extracellular [Ba²⁺]. Thus it was concluded that ATP stimulated PLD activity in direct proportion to the influx of divalent cations through the P2Z ion channel and this PLD activity was insensitive to changes in bulk cytosolic [Ca²⁺]. The calmodulin (Ca²⁺/CaM) inhibitor, trifluoperazine (TFP) inhibited ionomycin- and ATP-stimulated PLD activity and ATP-stimulated apoptosis, but had no effect on PLD activity already activated by ATP. However, TFP inhibited ATP-stimulated Ca²⁺, Ba²⁺ and ethidium⁺ fluxes, at concentrations below those which inhibit Ca²⁺/CaM, suggesting that TFP inhibits the P2Z receptor. Similarly, the isoquinolinesulphonamide, KN-62, a selective inhibitor of Ca²⁺/CaM-dependent protein kinase II (CaMKII), also prevented ATP-stimulated apoptosis, but had no effect on pre-activated PLD. In addition, KN-62, and an analogue, KN-04, which has no effect on CaMKII, potently inhibited ATP-stimulated Ba²⁺ influx (IC₅₀ 12.7 ± 1.5 and 17.3 ± 2.7 nM, respectively), ATP-stimulated ethidium⁺ uptake (IC₅₀ 13.1 ± 2.6 and 37.2 ± 8.9 nM, respectively), ATP-stimulated phospholipase D activity (50% inhibition 5.9 ± 1.2 and 9.7 ± 2.8 nM, respectively) and ATP-induced shedding of the surface adhesion molecule, L-selectin (IC₅₀ 31.5 ± 4.5 and 78.7 ± 10.8 nM, respectively). They did not inhibit phorbol ester- or ionomycin-stimulated PLD activity or phorbol ester-induced L-selectin shedding. Neither KN-62 nor KN-04 (both 500 nM) have any effect on UTP-stimulated Ca²⁺ transients in fura-2-loaded human neutrophils, a response which is mediated by the P2Y₂ receptor, neither did they inhibit ATP-stimulated contractile responses mediated by the P2X₁ receptor of guinea pig urinary bladder. Thus, KN-62 and KN-04 are almost equipotent as P2Z inhibitors with IC₅₀s in the nanomolar, indicating that their actions cannot be due to CaMKII inhibition, but rather that they are potent and direct inhibitors of the P2Z receptor. Extracellular ATP-induced shedding of L-selectin from lymphocytes into the medium is a Ca²⁺-independent response. L-selectin is either cleaved by a metalloproteinase or a PLD with specificity for glycosylphosphatidylinositol (GPI). The novel hydroxamic acid-based zinc chelator, Ro-31-9790 blocks ATP-induced L-selectin shedding, but was without effect on ATP-induced Ba²⁺ influx or ATP-stimulated PLD activity. Furthermore, another zinc chelator, 1,10-phenanthroline, an inhibitor of a GPI-PLD, potentiated rather than inhibited ATP-stimulated PLD activity, suggesting that ATP-induced L-selectin shedding and ATP-stimulated PLD activity are independent of each other. Although extracellular ATP is the natural ligand for the lymphocyte P2Z receptor, it is less potent than BzATP in stimulating Ba²⁺ influx. Concentration-response curves for BzATP- and ATP-stimulated ethidium⁺ influx gave EC₅₀s 15.4 ± 1.4 µM and 85.6 ± 8.8 µM, respectively. The maximal response to ATP was only 69.8 ± 1.9% of that for BzATP. Hill coefficients were 3.17 ± 0.24 and 2.09 ± 0.45 for BzATP and ATP respectively, suggesting greater positive cooperativity for BzATP than for ATP in opening the P2Z-operated ion channel. A rank order of agonist potency of BzATP > ATP = 2MeSATP > ATPγS was observed for agonist-stimulated ethidium⁺ influx, while maximal influxes followed a rank order of BzATP > ATP > 2MeSATP > ATPγS. When ATP (300 -1000 µM) was added simultaneously with 30 µM BzATP (EC₉₀), it reduced both ethidium⁺ and Ba²⁺ fluxes by 30 - 40% relative to values observed with BzATP alone. KN-62, previously shown to be a specific inhibitor of the lymphocyte P2Z receptor, was a less potent antagonist of BzATP-induced fluxes than ATP, when maximal concentrations of both agonists (50 and 500 µM respectively) were used. However, when BzATP (18 µM) was used at a concentration equiactive with a maximally effective ATP concentration, KN-62 showed the same inhibitory potency for both agonists. The ecto-ATPase antagonist, ARL-67156, inhibited both ATP- and BzATP-stimulated Ba²⁺ influx, suggesting that the lower efficacy of ATP compared with BzATP was not due to preferential hydrolysis of ATP. Thus, the natural ligand, ATP, is a partial agonist for the P2Z receptor while BzATP is a full agonist. Moreover the competitive studies show that only a single class of P2-receptor (P2Z class) is expressed on human leukaemic lymphocytes. Both ATP- and BzATP-stimulated PLD activity were significantly inhibited (P < 0.05) when cells were suspended in iso-osmotic choline Cl medium. Choline⁺ was found to be a permeant for the P2Z ion channel, since ATP induced a large uptake of [¹⁴C]choline⁺ (60 to 150 µmol/ml intracellular water) during a 5 min incubation, which remained in the cells for several hours, and ATP was used to load cells with these levels of choline⁺. Intracellular choline⁺ inhibited ATP-, BzATP-, PMA- and ionomycin-stimulated PLD activity. Brief exposure of lymphocytes to ATP increased the subsequent basal rate of ethidium⁺ uptake, and this was prevented by intracellular choline⁺. It is proposed that P2Z-mediated Ca²⁺ influx in lymphocytes activates PLD leading to significantly changes of the phospholipid composition of the plasma membrane, which subsequently produces a permeability lesion, which in turn contributes to cell death.

Sources of variation contributing to production and quality attributes of Kyrgyz cashmere in Osh and Naryn provinces : implications for industry development

We aimed to quantify the sources of variation contributing to the production and quality of cashmere produced in five districts in Osh and Naryn provinces of Kyrgyzstan. In early spring 2008 mid-side cashmere samples were taken from 719 cashmere adult females, and 41 cashmere adult males and castrates. Samples came from 53 villages and a total of 156 farmers’ flocks. For 91 goats from 33 farmers in 13 villages of two districts that had been sampled earlier, cashmere was combed from the goat at the time of a second visit (end of April 2008) when the cashmere would normally be harvested. Following standard cashmere objective measurement, data were examined using general linear modelling to quantify the effects of potential determinants. The mean fibre diameter (MFD) of cashmere differed between provinces (Osh 15.7 μm, Naryn 16.7 μm; P = 4.4 × 10−20). About 42% of the cashmere was <16 μm, 48% was 16.0–18.0 μm and 9.5% was >18.0 μm. Most of the cashmere samples were coloured (81%), with 63% black and 19% white. The percentage of cashmere samples that were white declined as MFD increased (26% < 14 μm to 11% of >18 μm). The primary determinants of cashmere MFD of individual goats were age of goat (range 1.46 μm, P = 1.8 × 10−12) and farm (range 6.5 μm, P = 1.7 × 10−14). The lesser effects detected for sex (range 0.9 μm, P = 0.026) and colour of cashmere (range 1.8 μm, P = 0.023) were based on small sample sizes and are unreliable. Age of goat had important affects on fibre diameter variation (up to 1.7% in coefficient of variation, P = 5.8 × 10−6) and fibre curvature (2.5–5°/mm, P = 2.1 × 10−4). By far the greatest effect on fibre curvature was cashmere MFD (P = 3.0 × 10−104) with a smaller effect of sex (about 5°/mm, P = 3.0 × 10−6). Village effects were detected on fibre diameter variability (range 4.5% in coefficient of variation, P = 0.027) and fibre curvature (range 15°/mm, P = 1.6 × 10−7). There was a strong negative association between increasing MFD and declining fibre curvature (−5.11 ± 0.181°/mm per 1 μm; P = 7.1 × 10−121; r2 = 0.51). Average combed cashmere weight was 164 g, the clean cashmere content was 0.661 and median clean cashmere production was 110 g per goat (range 60–351 g). Combed cashmere production increased with altitude of the village, probably related to different moulting times as spring temperatures warmed up later in higher altitude villages up to 3200 masl. Measurements of combed cashmere MFD were coarser than the mid-side samples taken earlier in the year. There are farmers and cashmere goats in the sampled districts of Kyrgyzstan which produce the finest qualities of commercial cashmere as the vast majority of cashmere is fine, has low variation in fibre diameter and has fibre crimping (curvature) typical of Chinese and Mongolian cashmere. There is substantial scope to increase the production and commercial value of cashmere produced by Kyrgyz goats. In particular, some villages and farmers need to change their buck selection practices if they wish to produce acceptable cashmere. Farmers should separate their finer and white cashmere prior to sale.

Antihypertensive treatments obscure familial contributions to blood pressure variation

The linkage and association between inherent blood pressure and underlying genotype is potentially confounded by antihypertensive treatment. We estimated blood pressure variance components (genetic, shared environmental, individual-specific) in 767 adult volunteer families by using a variety of approaches to adjusting blood pressure of the 244 subjects (8.2%) receiving antihypertensive medications. The additive genetic component of variance for systolic pressure was 73.9 mm Hg(2) (SE, 8.8) when measured pressures (adjusted for age by gender within each generation) were used but fell to 61.4 mm Hg(2) (SE, 8.0) when treated subjects were excluded. When the relevant 95th percentile values were substituted for treated systolic pressures, the additive genetic component was 81.9 mm Hg(2) (SE, 9.5), but individual adjustments in systolic pressure ranged from -53.5 mm Hg to +64.5 mm Hg (mean, +17.2 mm Hg). Instead, when 10 mm Hg was added to treated systolic pressure, the additive genetic component rose to 86.6 mm Hg(2) (SE, 10.1). Similar changes were seen in the shared environment component of variance for systolic pressure and for the combined genetic and shared environmental (ie, familial) components of diastolic pressure. There was little change in the individual-specific variance component across any of the methods. Therefore, treated subjects contribute important information to the familial components of blood pressure variance. This information is lost if treated subjects are excluded and obscured by treatment effects if unadjusted measured pressures are used. Adding back an appropriate increment of pressure restores familial components, more closely reflects the pretreatment values, and should increase the power of genomic linkage and linkage disequilibrium analyses.

The influence of specific luminal factors on the colonic epithelium : high-dose butyrate and physical changes suppress early carcinogenic events in rats

INTRODUCTION Although luminal delivery of butyrate is one putative mechanism by which biology of the colonic epithelium might be influenced by changes in luminal contents, there is a paucity of supportive cause–effect evidence. This study aimed to directly establish whether distal colonic butyrate delivery is able to alter the response of the distal colonic epithelium to a carcinogen.
METHODS Groups of male Sprague-Dawley rats with chronically intubated colons received infusions of 80 mM butyrate or 0.9 percent saline into distal colon two or five times daily. Three weeks after exposure to azoxymethane (15 mg/kg subcutaneously), the density of aberrant crypts was quantified in distal colon.
RESULTS Infusions of 0.5 ml twice daily, whether containing saline or butyrate, decreased the number of aberrant crypt foci by 45 percent compared with rats receiving no infusions (P = 0.004, analysis of variance). Similar results were obtained when infusions were restricted to the postinitiation phase. When infusions were increased to 1 ml five times daily, saline infusions similarly suppressed aberrant crypt formation (38 percent), but butyrate infusions suppressed it to a greater degree (by 64 percent; P = 0.02 compared with saline infusion, t-test).
CONCLUSIONS High levels of butyrate delivery to the distal colonic lumen alter the epithelial response to a carcinogen in otherwise healthy rats. This finding directly supports the notion that the effects of butyrate on cells in vitro do occur in vivo provided a sufficient dose is delivered. The effect of infusion of liquid per se on the epithelial response highlights the potential impact physical changes alone can have on the colonic epithelium.

The projected impact of population and high-risk strategies for risk-factor control on coronary heart disease and stroke events

Objective: To model the impact of both population and high-risk strategies on cardiovascular disease (CVD) outcomes.

Design, setting and participants: A CVD risk-factor survey was carried out in rural south-eastern Australia from 2004 to 2006. Using a stratified random sample, data for 1116 participants aged 35–74 years were analysed. Applying the Framingham risk equations to risk-factor data, 5-year probabilities of a coronary heart disease event, stroke and cardiovascular event were calculated. The effect of different changes in risk factors were modelled to assess the extent to which cardiovascular diseases can be prevented by changing the risk factors at a population level (population strategy), among the high-risk individuals (high-risk strategy) or both.

Results: Among men, a population strategy could reduce cardiovascular events by 19.3% (193 per 1000 per 5 years), the high-risk strategy by 12.6% (126 per 1000) and a combined strategy by 24.1% (241 per 1000); and among women, by 21.9% (219 per 1000), 19.0% (190 per 1000) and 28.7% (287 per 1000), respectively.

Conclusions: For prevention of CVD in Australia, it is important both to treat high-risk individuals and to reduce the mean risk-factor levels in the population. We show how risk-factor survey data can be used to set targets for prevention and to monitor progress in line with the recommendations of the National Preventative Health Taskforce.

Sunlight exposure caused yellowing and increased mineral content in wool

This study determines how levels of various trace metals in wool and the colour of the fibre change as a result of sunlight exposure and treatment with chelating compounds during wool growth. Twenty-four yearling Merino sheep were clipped on the shoulders and rumps and fitted with sheep coats modified with transparent patches. Patches over the shoulder wool (one per sheep) were either polyethylene (PE) that transmits ultraviolet light or polyvinyl chloride (PVC) that excludes ultraviolet light. The rump wool on each sheep was treated either with a copper chelator treatment (kojic acid or methyl gentisate in aqueous alcohol) or aqueous alcohol only. For 12 of the sheep the rumps were exposed to sunlight through PE patches while rump wool on the other sheep was covered by the sheep coat. Wool was harvested after 11 weeks’ growth with yellowness (Y-Z) and individual mineral contents measured using the same clean wool sample. Sunlight exposure through PE patches caused a mean increase in Y-Z to 9.1 (shoulder) or 9.5–10.1 (rump) from a base level of 7.1–7.2 (shoulder) or 7.0–7.6 (rump) in wool protected by the sheep coat. In contrast, there was no significant change in Y-Z for the PVC patch (shoulder). Therefore, it appears that ultraviolet light damage caused the increased Y-Z. Most of the trace metals analysed increased in the shoulder wool exposed to sunlight but the paired differences for PVC were lower than PE. It appears that changes in fibre caused by sunlight exposure (especially ultraviolet light) facilitate adsorption of minerals from the environment, including the animal’s own suint. Application of the chelating compounds to the rump wool caused pronounced yellowing of the wool with Y-Z increase being most pronounced for kojic acid. Copper levels in the wool were reduced by kojic acid and methyl gentisate while calcium levels were increased by kojic acid and reduced by methyl gentisate. It is not clear from these findings whether minerals and copper in particular contribute to yellowing of wool. However, the different effects of sunlight and chelation on mineral contents in wool shown may well relate to alternative mechanisms of discoloration (i.e. photoyellowing versus bacterial).

Profile of position movement demands in elite junior Australian rules footballers

This study investigated the positional movement patterns in elite junior Australian Football (AF). Thirty players (17.1 ± 0.9 years) participating in this study were tracked over seven home games of the regular 2006 Victorian junior (Under 18) league season. Using lapsed-time video analysis, each position for an entire match was videotaped on three separate occasions over the course of the season. Data analysed included the number of individual efforts, duration and frequency of efforts; distance and percentage time for the classifications of standing, walking jogging, running and sprinting. Results showed that the midfield position travelled the greatest distance (4173 ± 238 m per quarter; p < 0.05; ES = .94) whilst the full forward/full back travelled the least (2605 ± 348 m per quarter, p < 0.05, ES = 1.21). For all positions, walking or jogging accounted for the greatest number of efforts (45-55%), conversely running and sprinting accounted for 5-13% of match efforts. The majority of efforts across all classifications were between 0-3.99 s. The data from this study provides further evidence that AF is an intermittent sport characterised by high intensity movements separated by low intensity movements at a ratio of one high intensity effort every 12-40 s. However, careful interpretation of the data is required when training junior AF players for specific positions, given the specific group studied.

The epidemiology of cryptosporidiosis in New Zealand, 1997-2006

Aims New Zealand has a high incidence of cryptosporidiosis compared to other developed countries. This study aimed to describe the epidemiology of this disease in detail and to identify potential risk factors.

Methods We analysed anonymous cryptosporidiosis notification (1997–2006) and hospitalisation data (1996–2006). Cases were designated as “urban” or “rural” and assigned a deprivation level based on their home address. Association between disease rates and animal density was studied using a simple linear regression model, at the territorial authority level.

Results Over the 10-year period 1997–2006, the average annual rate of notified cryptosporidiosis was 22.0 cases per 100,000 population. The number of hospitalisations was equivalent to 3.6% of the notified cases. There was only 1 reported fatality. The annual incidence of infection appeared fairly stable, but showed marked seasonality with a peak rate in spring (September–November in New Zealand). The highest rates were among Europeans, children 0–9 years of age, and those living in low deprivation areas. Notification rates showed large geographic variations, with rates in rural areas 2.8 times higher than in urban areas, and with rural areas also experiencing the most pronounced spring peak. At the territorial authority (TA) level, rates were also correlated with farm animal density.

Conclusions Most transmission of Cryptosporidium in New Zealand appears to be zoonotic: from farm animals to humans. Prevention should focus on reducing transmission in rural setting, though more research is needed to identify which strategies are likely to be most effective in that environment.

Use of silicone hydrogel contact lenses by Australian optometrists

Background: Prior to the launch of silcone hydrogel (Si-H) materials in Australia in 1999, only 1.6 per cent of lenses were prescribed on a continuous wear basis.

Methods: One thousand surveys were distributed randomly to practitioners in Australia during January 2000, 2001 and 2002 (total surveys 3,000). Each anonymous survey requested data about the next 10 patients fitted with contact lenses, including date, age, gender, new fitting or refitting, lens material type, lens design, frequency of replacement, modality of wear, uses per week and care regimen.

Results: Twenty per cent (599) were returned, reporting data on 5,976 fittings. A total of 710 fittings used Si-H contact lenses (11.9 per cent), which represented 18.6 per cent of all soft lens fittings. During the three years, the proportion of practitioners prescribing Si-H lenses increased from 42.2 to 52.5 per cent. In 2000, 43.8 per cent were daily wear, which decreased to 32.2 per cent by 2002. The solution system of choice for daily wear lenses was multipurpose solutions (98.4 per cent); the only alternative was hydrogen peroxide systems. Continuous wear represented 11.7 per cent of all fittings, ofwhich 85.7 per cent were Si-H, 3.0 per cent RGP lenses and 11.3 per cent conventional hydrogels. For continuous wear, 79.0 per cent of fittings were to existing wearers, whereas for daily wear, 59.4 per cent were existing wearers. More males were prescribed Si-H continuous wear contact lenses, while females were more likely to be prescribed Si-H on a daily wear basis.

Discussion: Si-H contact lenses were introduced to the Australian market as a continuous wear contact lens, yet many practitioners use this product for daily wear with multipurpose solutions. By 2002, more practitioners were prescribing Si-H contact lenses for continuous wear than in 2000, suggesting a growing confidence in that product for that mode of wear. A comparison with an earlier survey shows there is an increase in continuous wear from 1.6 per cent to 11.7 per cent over a five-year period.

Assessing volume of accelerometry data for reliability in preschool children

Purpose: This study examines what volume of accelerometry data (h·d-1) is required to reliably estimate preschool children’s physical activity and whether it is necessary to include weekday and weekend data.

Methods: Accelerometry data from 493 to 799 (depending on wear time) preschool children from the Melbourne-based Healthy Active Preschool Years study were used. The percentage of wear time each child spent in total (light–vigorous) physical activity was the main outcome. Hourly increments of daily data were analyzed. t-tests, controlling for age and clustering by center of recruitment, assessed the differences between weekday and weekend physical activity. Intraclass correlation coefficients estimated reliability for an individual day. Spearman–Brown prophecy formula estimated the number of days required to reach reliability estimates of 0.7, 0.8, and 0.9.

Results: The children spent a significantly greater percentage of time being physically active on weekend compared with weekdays regardless of the minimum number of hours included (t = 12.49–16.76, P < 0.001 for all). The number of days required to reach each of the predetermined reliability estimates increased as the number of hours of data per day decreased. For instance, 2.7–2.8 d of data were required to reach a reliability estimate of 0.7 with 10 or more hours of data per day; 3.3–3.4 d were required to meet the same reliability estimate for days with 7 h of data.

Conclusions: Future studies should ensure they include the minimum amount of data (hours per day and number of days) as identified in this study to meet at least a 0.7 reliability level and should report the level of reliability for their study. In addition to weekdays, at least one weekend day should be included in analyses to reliably estimate physical activity levels for preschool children.

Patterns of physical activity and sedentary behaviour in preschool children

Background
Little is known about patterns of sedentary behavior (SB) and physical activity among preschoolers. Therefore, in this observational study patterns of SB and moderate-to-vigorous physical activity (MVPA) were examined in detail throughout the week in preschool-aged boys and girls.

Methods
A sample of 703 Melbourne preschool children (387 boys; 4.6 ± 0.7 y) were included in data analysis. SB and MVPA data were collected using accelerometry over an eight-day period. Percentage of time per hour in SB and in MVPA between 08:00 h and 20:00 h was calculated. Multi-level logistic regression models were created to examine the hour-by-hour variability in SB and MVPA for boys and girls across weekdays and weekend days. Odds ratios (OR) were calculated to interpret differences in hour-by-hour SB and MVPA levels between boys and girls, and between weekdays and weekend days.

Results
The highest SB levels co-occurred with the lowest MVPA levels from the morning till the early afternoon on weekdays, and during the morning and around midday on weekends. Besides, participation in SB was the lowest and participation in MVPA was the highest from the mid afternoon till the evening on weekdays and weekend days. The variability across the hours in SB and, especially, in MVPA was rather small throughout weekdays and weekends. These patterns were found in both boys and girls. During some hours, girls were found to be more likely than boys to demonstrate higher SB levels (OR from 1.08 to 1.16; all p < 0.05) and lower MVPA levels (OR from 0.75 to 0.88; all p < 0.05), but differences were small. During weekends, hour-by-hour SB levels were more likely to be lower (OR from 0.74 to 0.98; all p < 0.05) and hour-by-hour MVPA levels were more likely to be higher (OR from 1.15 to 1.50; all p < 0.05), than during weekdays, in boys and girls.

Conclusion
Entire weekdays, especially from the morning till the early afternoon, and entire weekend days are opportunities to reduce SB and to promote MVPA in preschool-aged boys and girls. Particularly weekdays hold the greatest promise for improving SB and MVPA. No particular time of the week was found where one sex should be targeted.

Prospective evaluation of respiratory exacerbations in children with cystic fibrosis from newborn screening to 5 years of age

Background Newborn screening allows novel treatments for cystic fibrosis (CF) to be trialled in early childhood before irreversible lung injury occurs. As respiratory exacerbations are a potential trial outcome variable, we determined their rate, duration and clinical features in preschool children with CF; and whether they were associated with growth, lung structure and function at age 5 years. Methods: Respiratory exacerbations were recorded prospectively in Australasian CF Bronchoalveolar Lavage trial subjects from enrolment after newborn screening to age 5 years, when all participants underwent clinical assessment, chest CT scans and spirometry. Results 168 children (88 boys) experienced 2080 exacerbations, at an average rate of 3.66 exacerbations per person-year; 80.1% were community managed and 19.9% required hospital admission. There was an average increase in exacerbation rate of 9% (95% CI 4% to 14%; p<0.001) per year of age. Exacerbation rate differed by site (p<0.001) and was 26% lower (95% CI 12% to 38%) in children receiving 12 months of prophylactic antibiotics. The rate of exacerbations in the first 2 years was associated with reduced forced expiratory volume in 1 s z scores. Ever having a hospitalmanaged exacerbation was associated with bronchiectasis (OR 2.67, 95% CI 1.13 to 6.31) in chest CT scans, and lower weight z scores at 5 years of age (coefficient -0.39, 95% CI -0.74 to -0.05). Conclusions Respiratory exacerbations in young children are markers for progressive CF lung disease and are potential trial outcome measures for novel treatments in this age group.

Resting toucher: a time and motion analysis of elite lawn bowls

Whilst numerous investigations have explored the physical demands placed upon competitive sportspeople from a wide array of sports little is known about the physical demands placed on lawn bowlers. The purpose of this study was to ascertain the movement activities of Australian representative singles and pairs players and to determine the frequency and duration of these activities. One match each of two male and two female players (one singles and one pairs player per gender) were videotaped during an international tournament. During playback of the videotaped matches (n = 4), a single observer coded the players’ activities into five distinct categories (waiting, walking forward, walking backward, jogging and bowling) using a computerised video editing system (Gamebreaker™ Digital Video Analysis System). Field calibration of players over 30m for forward motions and 15m for the backward motion was performed to allow for the estimation of total distance covered during the match. Heart rate was monitored during each match. The duration of a match was found to be (mean ± SD) 1hr 28 ± 15mins. The total distance covered during each match was 2093 ± 276m. The mean percentage of match time spent in each motion was: waiting, 61.8 ± 9.3%; walking forward, 22.3 ± 5.6%; walking backward, 2.0 ± 0.4%; jogging, 1.1 ± 0.5%; and bowling, 8.5 ± 4.2%. Average heart rate was found to be 57 ± 7% of age-predicted HRmax with a maximum of 78 ± 9% of age-predicted HRmax. The results of this study suggest that playing lawn bowls at an international level requires light-moderate intensity activity similar to that reported for golf.