In situ observation of the aggregated morphology and interaction of dialkyldimethylammonium bromide with DNA at air/water interface by Brewster angle microscopy

The adsorption of DNA on the Langmuir film of a cationic surfactant, dioctadecyldimethylammonium bromide (DODA·Br), and the change of the aggregation morphology of the composite monolayer with respect to surface pressure have been investigated by Brewster angle microscopy (BAM). In contrast with the case of DODA·Br on pure water subphase, when DNA was dispersed into subphase, its adsorption to the interface monolayer through electrostatic interaction decreases the charge density and therefore promotes the formation of domain at low surface pressure. In addition, the electrostatic interaction changed the phase morphology of DODA·Br Langmuir monolayer under different surface pressure, that is, from flower-shaped crystalline domain on the pure water subphase to circular domain on the subphase dispersed with DNA. The result also shows that the monolayer of the composite at air/water interface under the high pressure is not homogeneous, but consists of incompletely fused domains. For the Langmuir film of the surfactant with shorter alkyl-chains, similar morphology can be observed both under the high and low surface pressure. But the tight-stacked circular domain is no longer observed.

PKC and CaMK in human skeletal muscle : effects of exercise

The effects of exercise on novel signalling enzymes in skeletal muscle of humans was investigated. It was shown that exercise increased the activity of a calcium and calmodulin activated kinase. High-intensity, but submaximal, exercise increased the activity of some but not all isoforms of protein kinase C, a lipid-activated kinase family. These findings suggest that these enzymes may be part of the signalling process leading to beneficial adaptation to repeated exercise as well as the control of function within skeletal muscle during exercise.

Intramuscular determinants of the VO₂ slow component in trained cyclists

Fifteen trained male cyclists had muscle biopsies and performed cycling tests to determine if relationships exist between the oxygen uptake response and various intramuscular variables. It was found that muscle oxidative capacity is better able to explain the oxygen uptake response during high intensity cycling than muscle fiber distribution.

Effects of starting strategy on 5-min cycling time-trial performance

The importance of pacing for middle-distance performance is well recognized, yet previous research has produced equivocal results. Twenty-six trained male cyclists ( V O_2peak 62.8+5.9 ml ·kg^-1 · min^-1· maximal aerobic power output 340+43 W; mean+s) performed three cycling time-trials where the total external work (102.7+13.7 kJ) for each trial was identical to the best of two 5-min habituation trials. Markers of aerobic and anaerobic metabolism were assessed in 12 participants. Power output during the first quarter of the time-trials was fixed to control external mechanical work done (25.7+3.4 kJ) and induce fast-, even-, and slow-starting strategies (60, 75, and 90 s, respectively). Finishing times for the fast-start time-trial (4:53+0:11 min:s) were shorter than for the even-start (5:04+0:11 min:s; 95% CI=5 to 18 s, effect size=0.65, P 50.001) and slow-start time-trial (5:09+0:11 min:s; 95% CI=7 to 24 s, effect size=1.00, P 50.001). Mean VO₂ during the fast-start trials (4.31+0.51 litres · min^-1) was 0.18+0.19 litres · min^-1 (95% CI=0.07 to 0.30 litres · min^-1, effect size=0.94, P =0.003) higher than the even- and 0.18+0.20 litres · min^-1 (95% CI=0.5 to 0.30 litres · min^-1, effect size=0.86, P =0.007) higher than the slow-start time-trial. Oxygen deficit was greatest during the first quarter of the fast-start trial but was lower than the even- and slow-start trials during the second quarter of the trial. Blood lactate and pH were similar between the three trials. In conclusion, performance during a 5-min cycling time-trial was improved with the adoption of a fast- rather than an even- or slow-starting strategy.

Assessing physical activity during recess using accelerometry

Background : Physical activity guidelines recommend children should engage in 60 min of moderate-to-vigorous physical activity (MVPA) a day. School recess presents an opportunity for children to be physically active during the school day. Limited research has investigated children's activity levels during recess and its contribution to physical activity recommendations. Moreover, no target for physical activity during recess has been set.

Methods : One hundred sixteen boys and 112 girls (aged 5–10 years) from 23 schools had their physical activity during recess quantified using a uniaxial accelerometer during three recess breaks on one school day. The percentage of time spent engaged in moderate, high, and very high intensity activity was calculated using existing thresholds.

Results : Boys engaged in more moderate, high, and very high intensity activity than girls. On average, boys and girls spent 32.9% and 23% of recess engaged in physical activity, respectively.

Conclusions : Boys engaged in higher intensity activities than girls. The results suggest that recess can contribute 28 min for boys and 21.5 min for girls toward the accumulation of recommended daily physical activity. However, the physical activity intensities that children engaged in were low during recess. On average, children in this study did not achieve 50% of recess time in physical activity. Interventions for increasing the physical activity of children in the playground are warranted.

Relationships between measures of fitness, physical activity, body composition and vascular function in children

Background : The prevalence of obesity and physical inactivity in Western countries has increased rapidly. Both are modifiable risk factors for cardiovascular disease. Atherosclerosis begins in childhood and endothelial dysfunction is its earliest detectable manifestation.

Methods : We assessed flow-mediated dilation (FMD) in 129 children (75 female; 10.3 + 0.3 yrs; 54 male; 10.4; 0.3 yrs). FMD was normalised for differences in the eliciting shear rate stimulus between subjects (SR_AUC). Fitness was assessed as peak oxygen uptake during an incremental treadmill exercise test (VO₂peak). Body composition was measured using a dual-energy X-ray absorptiometry (DEXA) scan. Physical activity (PA) was assessed using Actigraph accelerometers. The cohort was split into tertiles according to FMD% and also FMD% corrected for SR_AUC to gain insight into the determinants of vascular function.

Results : Across the cohort, significant correlations were observed between FMD%/SR_AUC and DEXA percentage fat (r = −0.23, p = 0.009) and percentage lean mass (r = 0.21, p = 0.008), and also with PA performed at moderate-to-high intensity (r = 0.363, p = 0.001). For children in the lowest FMD%/SR_AUC tertile, a stronger relationship with all PA measures was observed, particularly with high intensity PA (r = 0.572, P = 0.003). Regression analysis revealed that high intensity PA was the only predictor of impaired FMD%/SR_AUC.

Conclusions : These data suggest that traditional risk factors for CHD in adult populations impact upon vascular function in young people. Furthermore, it appears that individuals with impaired FMD may benefit from performing high intensity PA, whereas no relationships exist between FMD and lower intensities of PA or between PA and FMD in those subjects who possess preserved vascular function a priori.

Substituted naphthoquinones as novel amino acid sensitive reagents for the detection of latent fingermarks on paper surfaces

In this paper, we present our preliminary studies into naphthoquinones as novel reagents for the detection of latent fingermarks on paper. Latent fingermarks deposited on paper substrates were treated with solutions of selected naphthoquinones in ethyl acetate/HFE-7100, with subsequent heating. The selected compounds were 1,4-dihydroxy-2-naphthoic acid, 1,2-naphthoquinone-4-sulfonate, 2-methoxy-1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone. All of the tested compounds yielded purple-brown visible fingermarks, which also exhibited photoluminescence when illuminated with a high intensity filtered light source at 555nm and viewed through red goggles. Indirect heat using an oven at 150 ◦C for 1 h was found to be superior to direct heat with an iron, which while providing faster development lead to increased levels of background colouration. Luminescence spectrophotometry revealed differences in photoluminescence characteristics for fingermarks developed with the different naphthoquinones, with excitation over the range 530–590 nm. Luminescence spectrophotometry of developed lysine, glycine and serine spots on paper was used to confirm that the naphthoquinones were reacting with amino acids in the latent fingermark.

Effect of body tilt angle on fatigue and EMG activities in lower limbs during cycling

This study compared the rate of fatigue and lower limb EMG activities during high-intensity constantload cycling in upright and supine postures. Eleven active males performed seven cycling exercise tests: one upright graded test, four fatigue tests (two upright, two supine) and two EMG tests (one upright, one supine). During the fatigue tests participants initially performed a 10 s all-out effort followed by a constant-load test with 10 s all-out bouts interspersed every minute. The load for the initial two fatigue tests was 80% of the peak power (PP) achieved during the graded test and these continued until failure. The remaining two fatigue tests were performed at 20% PP and were limited to the times achieved during the 80% PP tests. During the EMG tests subjects performed a 10 s all-out effort followed by a constant-load test to failure at 80% PP. Normalised EMG activities (% maximum, NEMG) were assessed in five lower limb muscles. Maximum power and maximum EMG activity prior to each fatigue and EMG test were unaffected by posture. The rate of fatigue at 80% PP was significantly higher during supine compared with upright posture (-68 ± 14 vs. -26 ± 6 W min-1, respectively, P\0.05) and the divergence of the fatigue responses occurred by the second minute of exercise. NEMG responses were significantly higher in the supine posture by 1–4 min of exercise. Results show that fatigue is significantly greater during supine compared with upright high-intensity cycling and this effect is accompanied by a reduced activation of musculature that is active during cycling.

Seasonal reduction in physical activity and flow-mediated dilation in children

Purpose: Cardiovascular disease is a process that has its origins in childhood. Endothelial dysfunction is the earliest detectable manifestation of cardiovascular disease. This study aimed to assess the impact of seasonal changes in physical activity (PA) and body composition on conduit artery endothelial function in children.

Method: We studied 116 children (70 girls aged 10.7 ± 0.3 yr and 46 boys aged 10.7 ± 0.3 yr) on two occasions; in the northern summer (June) and late autumn (November). We assessed flow-mediated dilation (FMD) using high-resolution Doppler ultrasound. Body composition was measured by dual-energy x-ray absorptiometry. PA was assessed using accelerometry.

Results: FMD (10.0% ± 4.3% to 7.9% ± 3.9%, P < 0.001) and PA (94.1 ± 34.8 to 77.8 ± 33.7 min·d-1, P < 0.01) decreased, while percentage body fat increased (27.6% ± 6.8% to 28.0% ± 6.6%, P < 0.001) between summer and autumn. Decreases in FMD correlated with decreases in high-intensity PA (r = 0.23, P = 0.04), and change in high-intensity PA was the only predictor of change in FMD. No relationships were evident between changes in body composition and FMD.

Conclusions: Vascular function decreased between summer and autumn in this cohort. There were no relationships between change in FMD and changes in body composition or low/moderate-intensity PA. The associations between FMD and high-intensity PA suggests that future interventions should encourage this form of behavior, particularly at the times of year associated with lower PA.

Neuromuscular control and running economy is preserved in elite international triathletes after cycling

Running is the most important discipline for Olympic triathlon success. However, cycling impairs running muscle recruitment and performance in some highly trained triathletes; though it is not known if this occurs in elite international triathletes. The purpose of this study was to investigate the effect of cycling in two different protocols on running economy and neuromuscular control in elite international triathletes. Muscle recruitment and sagittal plane joint angles of the left lower extremity and running economy were compared between control (no preceding cycle) and transition (preceded by cycling) runs for two different cycle protocols (20-minute low-intensity and 50-minute high-intensity cycles) in seven elite international triathletes. Muscle recruitment and joint angles were not different between control and transition runs for either cycle protocols. Running economy was also not different between control and transition runs for the ow-intensity (62.4 ^ 4.5 vs. 62.1 ^ 4.0 ml/min/kg, p . 0.05) and high-intensity (63.4 ^ 3.5 vs. 63.3 ^ 4.3 ml/min/kg, p . 0.05) cycle protocols. The results of this study demonstrate that both low- and high-intensity cycles do not adversely influence neuromuscular control and running economy in elite international triathletes.

Change in running kinematics after cycling are related to alterations in running economy in triathletes

Emerging evidence suggests that cycling may influence neuromuscular control during subsequent running but the relationship between altered neuromuscular control and run performance in triathletes is not well understood. The aim of this study was to determine if a 45 min high-intensity cycle influences lower limb movement and muscle recruitment during running and whether changes in limb movement or muscle recruitment are associated with changes in running economy (RE) after cycling. RE, muscle activity (surface electromyography) and limb movement (sagittal plane kinematics) were compared between a control run (no preceding cycle) and a run performed after a 45 min high-intensity cycle in 15 moderately trained triathletes. Muscle recruitment and kinematics during running after cycling were altered in 7 of 15 (46%) triathletes. Changes in kinematics at the knee and ankle were significantly associated with the change in VO₂ after cycling (p < 0.05). The change in ankle angle at foot contact alone explained 67.1% of the variance in VO₂. These findings suggest that cycling does influence limb movement and muscle recruitment in some triathletes and that changes in kinematics, especially at the ankle, are closely related to alterations in running economy after cycling.

Sprint cycling performance is maintained with short-term contrast water immersion

Purpose: Given the widespread use of water immersion during recovery from exercise, we aimed to investigate the effect of contrast water immersion on recovery of sprint cycling performance, HR and, blood lactate.

Methods: Two groups completed high-intensity sprint exercise before and after a 30-min randomized recovery. The Wingate group (n = 8) performed 3 x 30-s Wingate tests (4-min rest periods). The repeated intermittent sprint group (n = 8) cycled for alternating 30-s periods at 40% of predetermined maximum power and 120% maximum power, until exhaustion. Both groups completed three trials using a different recovery treatment for each trial (balanced randomized application). Recovery treatments were passive rest, 1:1 contrast water immersion (2.5 min of cold (8-C) to 2.5 min of hot (40-C)), and 1:4 contrast water immersion (1 min of cold to 4 min of hot). Blood lactate and HR were recorded throughout, and peak power and total work for pre- and postrecovery Wingate performance and exercise time and total work for repeated sprinting were recorded.

Results: Recovery of Wingate peak power was 8% greater after 1:4 contrast water immersion than after passive rest, whereas both contrast water immersion ratios provided a greater recovery of exercise time (È10%) and total work (È14%) for repeated sprinting than for passive rest. Blood lactate was similar between trials. Compared with passive rest, HR initially declined more slowly during contrast water immersion but increased with each transition to a cold immersion phase.

Conclusions: These data support contrast water immersion being effective in maintaining performance during a short-term recovery from sprint exercise. This effect needs further investigation but is likely explained by cardiovascular mechanisms, shown here by an elevation in HR upon each cold immersion.

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.