A comparison of two global positioning system devices for team-sport running protocols

The comparability and reliability of global positioning system (GPS) devices during running protocols associated with team-sports was investigated. Fourteen moderately-trained males completed 690 m of straight-line movements, a 570 m change of direction (COD) course and a 642.5 m team-sport simulated circuit (TSSC); on two occasions. Participants wore a FieldWiz GPS device and a Catapult MinimaxX S4 10-Hz GPS device. Typical error of measurement (TE) and coefficient of variation (CV%) were calculated between GPS devices, for the variables of total distance and peak speed. Reliability comparisons were made within FieldWiz GPS devices, between sessions. Small TE were observed between FieldWiz and Catapult GPS devices for total distance and peak speed during straight-line (16.9 m [2%], 1.2 km·h⁻¹ [4%]), COD (31.8 m [6%], 0.4 km·h⁻¹ [2%]) and TSSC protocols (12.9 m [2%], 0.5 km·h⁻¹ [2%]), respectively, with no significant mean bias (p > 0.05). Small TE were also observed for the FieldWiz GPS device between sessions (p > 0.05) for straight-line (9.6 m [1%], 0.2 km·h⁻¹ [1%]), COD (12.8 m [2%], 0.2 km·h⁻¹ [1%]) and TSSC protocols (6.9 m [1%], 0.6 km·h⁻¹ [2%]), respectively. Data from the FieldWiz GPS device appears comparable to established devices and reliable across a range of movement patterns associated with team-sports.     

Direct comparison of two actigraphy devices with polysomnographically recorded naps in healthy young adults

The last 20 yrs have seen a marked increase in studies utilizing actigraphy in free-living environments. The aim of the present study is to directly compare two commercially available actigraph devices with concurrent polysomnography (PSG) during a daytime nap in healthy young adults. Thirty healthy young adults, ages 18–31 (mean 20.77 yrs, SD 3.14 yrs) simultaneously wore AW-64 and GT3X+ devices during a polysomnographically recorded nap. Mann-Whitney U (M-U) test, intraclass correlation coefficients, and Bland-Altman statistic were used to compare total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), and sleep efficiency (SE) between the two actigraphs and PSG. Epoch-by-epoch (EBE) agreement was calculated to determine accuracy, sensitivity, specificity, predictive values for sleep (PVS) and wake (PVW), and kappa and prevalence- and bias-adjusted kappa (PABAK) coefficients. All frequency settings provided by the devices were examined. For both actigraphs, EBE analysis found accuracy, sensitivity, specificity, PVS, and PVW comparable to previous reports of other similar devices. Kappa and PABAK coefficients showed moderate to high agreement with PSG depending on device settings. The GT3X+ overestimated TST and SE, and underestimated SOL and WASO, whereas no significant difference was found between AW-64 and PSG. However, GT3X+ showed overall better EBE agreements to PSG than AW-64. We conclude that both actigraphs are valid and reliable devices for detecting sleep/wake diurnal patterns. The choice between devices should be based on several parameters as reliability, cost of the device, scoring algorithm, target population, experimental condition, and aims of the study (e.g., sleep and/or physical activity). (Author correspondence: smednick@ucr.edu)     

Collection devices for cervicovaginal cytology: a comparison

OBJECTIVE: To compare cervicovaginal smears obtained by a cotton-tipped swab with those obtained by cervix brush and modified Ayre spatula. STUDY DESIGN: A combined cervicovaginal smear was collected from 100 women using 3 different collection devices: cotton-tipped swab, cervix brush, and modified Ayre spatula. In each patient a set of 3 smears was collected by the same cytotechnologist using all 3 devices in random order. Smears were evaluated using parameters mandatory for an optimal smear: evenly dispersed, well-preserved, adequate cells from the transformation zone. The cost and availability of the collection devices were also considered. RESULTS: The swab was the most effective device in obtaining thin, evenly spread, adequate, well-preserved smears as against the cervix brush and Ayre spatula. The pickup of abnormal cells was similar with the cotton-tipped swab and cervix brush, while the Ayre spatula failed to yield high grade squamous intraepithelial lesions, atypical glandular cells of undetermined significance and adenocarcinoma cells. The cotton-tipped swab proved to be the most cost effective. CONCLUSION: A properly prepared cotton-tipped swab is an inexpensive, readily available, nontraumatic collection device that yields smear of optimal quality.     

Temperature dependence of oscillation in squid axons: comparison of experiments with computations

The temperature dependence of the oscillatory behavior of experimental and computed axons was compared. In the experimental study of space-clamped giant axons of the squid, small oscillations after a single threshold spike were measured using the double glucose gap over the temperature range 10°-30°C during treatment with three concentrations of external CaCl₂ solutions. Calcium concentration had little effect on frequency, as was found also by Huxley in his computations at 18.5°C for a fiber at rest. The Q₁₀ both for the experimental and for the computed axon of FitzHugh was 2.25. The experimental measurements of the frequency of oscillations near threshold agree extremely well with the Hodgkin-Huxley calculations.     

Auto-CPAP therapy based on the forced oscillation technique.

Autoadjusting CPAP devices (APAP) are designed to continuously adjust the positive pressure to the required levels, and thus increase treatment quality and patient compliance. The results of APAP treatment strongly depend on the control mechanism of the respective APAP device. In agreement with other working groups, we have recently shown that the forced oscillation technique (FOT) is capable of detecting incipient upper airway obstruction prior to physiological reactions such as the onset of increasing esophageal pressure swings or microarousals. Therefore we studied efficacy and acceptance of a novel APAP device controlled exclusively by FOT. 100 consecutive patients with OSAS confirmed by polysomnography (mean AHI 47.9 +/- 22.6) and daytime sleepiness (Epworth sleepiness scale, ESS 12.6 +/- 3.9) were randomized to either APAP treatment (n = 50) or conventional CPAP treatment (n = 50). Polysomnographies were performed at the second treatment night and subjective sleepiness (modified ESS) was established in the morning. The respiratory disturbance was largely normalized in both treatment groups in the second treatment night (AHI 4.7 +/- 5.3 vs. 3.7 +/- 3.4; n.s.). Both groups showed largely improved sleep profiles and had markedly reduced ESS-scores (6.6 +/- 3.6 vs. 7.0 +/- 3.4; n.s.). The mean treatment pressure during APAP was significantly lower than during CPAP treatment (6.0 +/- 2.0 vs. 9.0 +/- 1.8 mbar; p < 0.001). There were no significant differences between APAP and CPAP treatment in any parameter of efficacy or acceptance. APAP treatment with this device controlled exclusively by FOT is well accepted by the patients and permits an adequate treatment of OSAS without the need for invidiual CPAP titration.     

Polysaccharide production: Experimental comparison of the performance of four mixing devices

This investigation was undertaken with the objective to compare experimentally the performance of four different mixing devices for the production of the polysaccharide pullulan with Aureobasidium pullulans (2552). Fermentations were performed using identical bioreactors with respectively an assembly of three Rushton turbines (RTB), a helical ribbon impeller (HR) and two different reciprocating plates (RPB1, RPB2). Each mixing vessel had identical geometry and working volume (18 L). These four fermentations were performed with an equal level of power input per unit volume (1000?W/m³) and gas flow rate (0.5 vvm, 9 L/min). For each system, the evolution of biomass, polysaccharide concentration, dissolved oxygen and agitation speed or frequency were recorded as a function of time along with the rheological properties of the culture broths. The type of mixing device used had a significant impact on the rate of biomass production and on polysaccharide physical properties. However, the rate of polysaccharide production appears to be less sensitive to the bioreactor design. The overall productivity, which represents the ability of micro-organisms to convert rapidly substrate into biomass and polysaccharide, was maximised using the RPB2 system. The quality of the synthesised polysaccharide, in terms of viscosity producing power, was highest using the HR system but the overall productivity was very low. Thus, the best compromise between productivity and product quality was achieved with the RPB2.     

Comparison of posturographic outcomes between two different devices

The Interactive Balance System (IBS), a posturography device for assessing posture control, is widely used in clinical and rehabilitation settings. However, data on the validity of the device are unavailable. Fluctuations of the center of pressure (COP) were measured in 24 healthy participants (age: 29 ± 5 (mean ± SD) years, 12 females) synchronously using the IBS, which was rigidly mounted on a Kistler platform. Four different bipedal conditions were examined: eyes open or closed on stable or soft surfaces. Time series were compared using congruity (CON, proportion of the measurement time during which values of both devices changed similarly in direction), whereas IBS-specific postural outcomes were correlated with traditional postural control outcomes of the Kistler force platform. The time-displacement curves showed similar shapes for CON (>0.9) for each of the four standing conditions without differences between male and female participants (P > 0.39). The path length results of both devices showed very high linear associations, explaining on average 92% (medio-lateral) or 96% (anterior-posterior) of the common variance. The Kistler path length of the anterior-posterior direction revealed nearly perfect linear associations with the stability index of the IBS (r² > 0.99). The results of this study indicate that the IBS provides valid posturographic results. Since the medial-lateral and anterior-posterior trajectories of the IBS can be used to calculate COP fluctuations, comparisons between different measurement systems are possible.     

Measurement of total respiratory impedance in calves by the forced oscillation technique

We have determined the resistance (Rrs) and the reactance (Xrs) of the total respiratory system in unsedated spontaneously breathing calves at various frequencies. A pseudorandom noise pressure wave was produced at the nostrils of the animals by means of a loudspeaker adapted to the nose by a tightly fitting mask. A Fourier analysis of the pressure in the nostrils and flow signals yielded mean Rrs and Xrs, over 16 s, at frequencies of 2-26 Hz. A good correlation was found between values of pulmonary resistances measured by the isovolume method at the respiratory frequency of animals and values obtained at a frequency of 6 Hz by use of our technique. The linearity of the respiratory system, the reproducibility of the technique, and the effects of upper airways on results have been studied. In healthy calves, Rrs increases with frequency. Mean resonant frequency is 7.5 Hz. Bronchospasm was induced in six calves by administration of intravenous organophosphates. Rrs tended to decrease with increasing frequency. Resonant frequency exceeded 26 Hz. All parameters returned to initial values after administration of atropine. In healthy calves, atropine produces a decrease in Rrs, especially at low frequencies. Values of resonant frequency are not modified.     

Measurement of total respiratory impedance in infants by the forced oscillation technique

The forced oscillation technique according to Làndsér et al. (J. Appl. Physiol. 41:101-106, 1976) was modified for use in infants. Adaptations, including a flexible tube to connect the infant to the measuring system and a bias flow to avoid rebreathing, did not influence impedance values. The linearity of the respiratory system was assessed and confirmed by 1) applying pseudo-random noise oscillations at three different amplitudes to 7 infants and 2) comparing in 12 infants impedance values obtained with pseudo-random noise and with sinusoidal oscillations at 12 and 32 Hz. Intersubject variability, averaged for all frequencies, was 6%. In 17 infants the relative error (+/- SD) between two series of five measurements within a time interval of 15 min was 0.5 +/- 5.7%. No statistically significant difference was found between impedance values before and after repositioning of the infant's head, whereas rotation resulted in a decrease in resistance and no effect on reactance. Our results indicate that the infant-adapted forced pseudo-random noise oscillation technique has the potential to give valuable information about ventilatory lung function in infants.     

DNA probe attachment on plastic surfaces and microfluidic hybridization array channel devices with sample oscillation

DNA probe immobilization on plastic surfaces and device assembly are both critical to the fabrication of microfluidic hybridization array channel (MHAC) devices. Three oligonucleotide (oligo) probe immobilization procedures were investigated for attaching oligo probes on four different types of plastic surfaces (polystyrene, polycarbonate, poly(methylmethacrylate), and polypropylene). These procedures are the Surmodics procedure, the cetyltrimethylammonium bromide (CTAB) procedure, and the Reacti-Bind procedure. To determine the optimal plastic substrate and attachment chemistry for array fabrication, we investigated plastic hydrophobicity, intrinsic fluorescence, and oligo attachment efficiency. The Reacti-Bind procedure is least effective for attaching oligo probes in the microarray format. The CTAB procedure performs well enough to use in array fabrication, and the concentration of CTAB has a significant effect on oligo immobilization efficiency. We also found that use of amine-modified oligo probes resulted in better immobilization efficiency than use of unmodified oligos with the CTAB procedure. The oligo probe immobilization on plastic surfaces by the Surmodics procedure is the most effective with regard to probe spot quality and hybridization sensitivity. A DNA hybridization assay on such a device results in a limit of detection of 12pM. Utilizing a CO(2) IR laser machining and adhesive layer approach, we have developed an improved procedure for realizing a DNA microarray inside a microfluidic channel. This device fabrication procedure allows for more feasible spot placement in the channel and reduced sample adsorption by adhesive tapes used in the fabrication procedure. We also demonstrated improved hybridization kinetics and increased detection sensitivity in MHAC devices by implementing sample oscillation inside the channel. A limit of detection of 5pM has been achieved in MHAC devices with sample oscillation.     

High-performance liquid chromatography determination of flunitrazepam and its metabolites in plasma by use of column-switching technique: comparison of two extraction columns

A study, using on-line column-switching high-performance liquid chromatography, evaluated two different extraction columns for the determination of flunitrazepam and its major metabolites: 7-aminoflunitrazepam, 7-acetamidoflunitrazepam and desmethylflunitrazepam. The procedure was based on the enrichment of benzodiazepines on the extraction column, followed by transfer of the compounds to the analytical column. The two extraction columns were compared: the first column was a BioTrap 500 MS (hydrophobic polymer), 20×4 mm I.D., and the second was a LiChrospher RP-18 ADS, 25×4 mm I.D. The analytical column used was a LiChrospher select B RP-8, 125×3 mm I.D. with 5 μm particle size. The extraction conditions for the two pre-concentration columns, such as extraction temperature, buffer concentration, buffer pH, acetonitrile percentage and flow-rate, were studied for the extraction from plasma of flunitrazepam and its metabolites mentioned above. The mobile phase of the analytical column was isocratic and composed of acetonitrile–20 mM phosphate buffer at pH 2.1 (35:65, v/v) and at a flow-rate of 0.3 ml/min.     

Comparison of two devices and two breathing patterns for exhaled breath condensate sampling

Introduction

Analysis of exhaled breath condensate (EBC) is a noninvasive method to access the epithelial lining fluid of the lungs. Due to standardization problems the method has not entered clinical practice. The aim of the study was to assess the comparability for two commercially available devices in healthy controls. In addition, we assessed different breathing patterns in healthy controls with protein markers to analyze the source of the EBC.

Methods

EBC was collected from ten subjects using the RTube and ECoScreen Turbo in a randomized crossover design, twice with every device - once in tidal breathing and once in hyperventilation. EBC conductivity, pH, surfactant protein A, Clara cell secretory protein and total protein were assessed. Bland-Altman plots were constructed to display the influence of different devices or breathing patterns and the intra-class correlation coefficient (ICC) was calculated. The volatile organic compound profile was measured using the electronic nose Cyranose 320. For the analysis of these data, the linear discriminant analysis, the Mahalanobis distances and the cross-validation values (CVV) were calculated.

Results

Neither the device nor the breathing pattern significantly altered EBC pH or conductivity. ICCs ranged from 0.61 to 0.92 demonstrating moderate to very good agreement. Protein measurements were greatly influenced by breathing pattern, the device used, and the way in which the results were reported. The electronic nose could distinguish between different breathing patterns and devices, resulting in Mahalanobis distances greater than 2 and CVVs ranging from 64% to 87%.

Conclusion

EBC pH and (to a lesser extent) EBC conductivity are stable parameters that are not influenced by either the device or the breathing patterns. Protein measurements remain uncertain due to problems of standardization. We conclude that the influence of the breathing maneuver translates into the necessity to keep the volume of ventilated air constant in further studies.     

Evaluating the forced oscillation technique in the detection of early smoking-induced respiratory changes

Background  

Early detection of the effects of smoking is of the utmost importance in the prevention of chronic obstructive pulmonary disease (COPD). The forced oscillation technique (FOT) is easy to perform since it requires only tidal breathing and offers a detailed approach to investigate the mechanical properties of the respiratory system. The FOT was recently suggested as an attractive alternative for diagnosing initial obstruction in COPD, which may be helpful in detecting COPD in its initial phases. Thus, the purpose of this study was twofold: (1) to evaluate the ability of FOT to detect early smoking-induced respiratory alterations; and (2) to compare the sensitivity of FOT with spirometry in a sample of low tobacco-dose subjects.