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Results for “Reproducibility”

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PubMed1991

Doppler flow velocity waveforms in the fetal cardiac outflow tract: reproducibility of waveform recording and analysis.

Reproducibility of flow velocity waveform recording and analysis was studied at fetal cardiac level (ductus arteriosus, pulmonary artery and ascending aorta) in 42 normal pregnancies. The flow velocity parameters studied were the peak systolic velocity (PSV), acceleration time (ACT), acceleration velocity (ACV), average velocity (AV) and flow velocity integral (FVI). In each patient, two consecutive measurements were performed (time delay 15 min) and of each measurement two hardcopies were analysed. A high reproducibility was achieved for the PSV, AV and FVI in all vessels studied; the coefficients of variation between readings of hardcopies were less than or equal to 3%, and the coefficients of variation between tests within patients were less than or equal to 7%. A moderate reproducibility was achieved for the ACT in the ascending aorta and pulmonary artery; the variation between tests was large for the ductus arteriosus. The reproducibility of the ACV was poor.

Aorta↗

PubMed1992

Reproducibility of transcranial Dopplersonography: a validation study.

Transcranial Doppler-sonography (TCD) is a useful noninvasive technique for the measurement of intracranial arterial blood flow velocity. The present study evaluated the reproducibility of this method for repeated measurements of flow velocity in the anterior, middle and posterior cerebral, and basilar arteries. Thirty-six patients (23 males and 13 females) were studied. Three measurements were made by the same examiner on each patient with a time interval of 1 h between the first and the second examination, and about 24 h between the first and the third examination. The statistical evaluation for the reproducibility was performed by calculating the correlation coefficient (r). The results showed good reproducibility of TCD for all arteries both between the first and second and between the first and third measurements (r = 0.78-0.97; p less than 0.001), but when the middle cerebral artery mean velocity is low the posterior cerebral artery reproducibility is poorest (r = 0.42-0.54).

Blood Flow Velocity↗

PubMed1994

Can a total body irradiation technique be fast and reproducible?

PURPOSE: Total body irradiation (TBI) is frequently a complex and time-consuming technique that significantly overloads Radiation Oncology departments. In an attempt to shorten TBI setup and treatment time we aimed to develop a system where the lung blocks are fixed with optimal precision to the build-up booster lucite screen while the patient is immobilized in a reproducible upright position. METHODS AND MATERIALS: Fifteen patients diagnosed with leukemia were conditioned before bone marrow transplant since March 1992. Patients were immobilized in a semistanding position in a special stand with arm bars and hand grips. Treatment was delivered with a 6 MV x-ray horizontal beam. Six fractions of 2.25 Gy (mean instantaneous dose rate of 13.8 +/- 3.8 cGy/min) were delivered twice a day over 3 days (total dose: 13.5 Gy). Each fraction was given in alternating AP (facing the beam) and PA (turning the back) projections. Customized lung blocks (35% transmission) were used to assure a maximum lung dose of 10 +/- 0.5 Gy. The blocks were taped to a 1 cm thick lucite screen interposed between the source and the patient. Lung shields were checked by port films before each fraction. The reproducibility of the patient's positioning (and lung shielding) was evaluated by measuring the horizontal and vertical deviations of the infero-external corners of the lung blocks in the port films in relation to the same point in the simulation films. In vivo dosimetry (thermoluminescence and diodes) was performed by placing dosimeters and probes in the central axis and in several off-axis sites. RESULTS: The mean horizontal and vertical deviations were 3.5 +/- 4.1 mm and 7.5 +/- 5.9 mm for the anterior fields, and 4.1 +/- 4.1 mm and 6.9 +/- 6.4 mm for the posterior fields. An acceptable position of the blocks was considered when deviations were < 5 mm horizontally and/or < 10 mm vertically. The mean time per fraction (i.e., interval between the patient's entering and leaving the treatment room) was 35 +/- 5 min. CONCLUSIONS: A satisfactory level of reproducibility can be reached with this technique. The reasonably short treatment time contributes to reproducibility and patient comfort.

Bone Marrow↗

PubMed1994

Quantitative MR imaging of lumbar intervertebral disc and vertebral bodies: methodology, reproducibility, and preliminary results.

Since relaxation times are influenced by the hydration of the tissue and the chemical environment of the water molecules, T1 and T2 measurements (quantitative MRI) could be used as an indicator for the water content and the biochemical composition of lumbar intervertebral discs. The discriminating power of quantitative MRI for tissue characterization in individuals (for clinical diagnosis) and in cohorts (e.g. for investigations on disc physiology or composition) relies on the reproducibility in relation to the expected tissue differences. We therefore investigated the reproducibility in vitro (lumbar spine phantom) and in vivo (10 volunteers). To estimate the differences between normal and pathologic tissues in vivo, 100 normal and 20 herniated intervertebral discs were examined by quantitative MRI in a first application of our method. The relaxation times were calculated from a set of 20 images obtained with five single-slice/multi-echo sequences at different TR values on a commercial whole-body system (1.5 T). We have found a satisfactory reproducibility in vitro (T1: 1.9%; T2: 6.2%), while the reproducibility was less satisfactory in vivo (T1: 16.4%; T2: 13.4%). Calculated from theses values, differences in relaxation times of various tissues must exceed 486 ms for T1 and 24 ms for T2 (tolerance limits) to allow discrimination with a 95% confidence in individuals. We observed statistically significant (p = 0.001) mean differences between normal (n = 100) and herniated (n = 20) intervertebral discs (delta T1: 196 ms; delta T2: 15 ms). Although statistical significant in cohorts, a discrimination of normal and herniated intervertebral discs is limited by quantitative MRI in individuals, since the differences are smaller than the tolerance limits necessary for a reliable clinical diagnosis. However, our results indicate that variations in the disc hydration and/or composition can be noninvasively detected by quantitative MRI in studies of cohorts with sufficient accuracy.

Adolescent↗

PubMed1990

Reproducibility of quantitative myocardial contrast echocardiography.

To determine whether myocardial contrast echocardiography is quantitatively reproducible, repeated intracoronary injections of sonicated albumin (5%) were performed in eight open chest dogs. Paired injections were performed at baseline, during ischemia produced by ligation of a coronary artery, and during hyperemia induced by intravenous infusion of 0.75 mg/kg body weight of dipyridamole. Contrast washout curves were generated for the left anterior descending coronary artery territory (ischemic area) and left circumflex coronary artery territory (nonischemic area) by beat per beat analysis of frozen end-diastolic frames of left ventricular short-axis views. Peak contrast intensity, contrast washout half-time and area under the curve were derived from these curves. A total of 75 contrast washout curves were analyzed for the study of interinjection, intraobserver and interobserver reproducibility. The correlation coefficients between measurements obtained from paired injections of the echocardiographic contrast agent (interinjection reproducibility) ranged from 0.78 for peak contrast intensity to 0.87 for area under the curve. Percent error varied between 14.7% and 24.7%. The intraobserver variability in measurements was less than the interinjection variability, with a cumulative mean percent error of 17.8% and correlation coefficients of 0.72 (peak contrast intensity), 0.95 (area under the curve) and 0.96 (washout half-time). Interobserver correlation for all indexes was high (r = 0.92 to 0.96). It is concluded that peak contrast intensity, contrast washout half-time and the area under the curve derived from myocardial contrast washout curves can be measured reproducibly from videotapes. In addition, the variability between two injections attempted under identical conditions is greater than reader variability from videotapes.

Albumins↗

PubMed1994

Evaluation of the MOS SF-36 physical functioning scale (PF-10): I. Unidimensionality and reproducibility of the Rasch item scale.

Indexes developed to measure physical functioning as an essential component of general health status are often based on sets of hierarchically-structured items intended to represent a broad underlying concept. Rasch Item Response Theory (IRT) provides a methodology to examine the hierarchical structure, unidimensionality, and reproducibility of item positions (calibrations) along a scale. Data gathered on the 10-item Physical Functioning Scale (PF-10) from a large sample of Medical Outcomes Study patients (N = 3445) were used to examine the hierarchical order, unidimensionality, and reproducibility of item calibrations. Rasch-IRT analyses generated an empirical item hierarchy, confirmed the unidimensionality of the PF-10 for most patients, and established the reproducibility of item calibrations across patient populations and repeated tests. These findings support the content validity of the PF-10 as a measure of physical functioning and suggest that valid Rasch-IRT summary scores could be generated as an alternative to the current Likert summative scores. Unidimensionality and reproducibility of the item scale are essential prerequisites for the development of Rasch-based person measures of physical functioning that can be used across populations and over repeated tests.

Activities of Daily Living↗

PubMed2005

Long-term reproducibility of routine ambulatory blood pressure monitoring in stable pediatric renal transplant recipients.

BACKGROUND: The aim of this study was to evaluate, in stable pediatric renal transplant recipients, the long-term reproducibility of average office and ambulatory blood pressure (BP) readings and day-to-night BP variability under similar clinical conditions. METHODS: The study involved 18 pediatric kidney transplant recipients who had repeated routine office and 24-h ambulatory BP monitoring (ABPM) in three visits, 12 months apart, over a 2-year period. Reproducibility of office and ambulatory BP averages between pairwise measurements were analyzed by calculating the mean difference and the standard deviation of the difference (SDD). Nondippers were arbitrarily defined by applying both a pediatric and an adult definition, respectively. RESULTS: Throughout the 2-year period, there were no significant differences in mean office, 24-h, daytime, night-time systolic, and diastolic BP values. Overall, SDD were lower for ambulatory BP recordings than for office BP measurements indicating a better long-term reproducibility for ABPM compared with office BP readings. The SDD for systolic and diastolic BP ranged from 12.4 to 13.7 and 6.3 to 9.5 for office BP and from 6.2 to 7.3 and 5.1 to 5.6 for 24-h BP, respectively. Regardless of the definition applied to define dipper and nondipper status, only half of the study group showed consistency in their circadian BP variability when comparing the three ABPMs. CONCLUSIONS: The present study demonstrates that long-term reproducibility of ABPM is superior to that for office measurements. Day-to-night BP variability, however, appears to change over time, making it questionable to classify a recipient as a dipper or nondipper during a single ABPM recording.

Adolescent↗

PubMed2006

Medium- and long-term reproducibility of self-reported exposure to physical ergonomics factors at work.

INTRODUCTION: The literature is sparse on reproducibility of self-reported exposure to physical ergonomics risk factors for musculoskeletal disorders (MSDs). Aims of this study were to evaluate, in a cohort of workers interviewed up to three times: 1-year test-retest reliability; and 5- and 6-year recall of physical exposures. We also examined whether reproducibility was influenced by the presence of UE MSD or by technological changes introduced between the last two surveys. METHODS: A cohort of automobile manufacturing employees was interviewed at baseline, one and six years later about work history, physical and psychosocial exposures at work, upper limb symptoms, injury and medical history, and demographics. Agreement between interviews was evaluated by intraclass correlation and Spearman coefficients. Differences in exposure between 1- and 6-year follow-up were analyzed by Wilcoxon matched-pairs signed-ranks test. RESULTS: Large and significant decreases in work pace and physical effort were observed from baseline, although an upper extremity composite index was quite stable in the total population. One-year test-retest reliability was fair to good for the composite exposure index (ICC=0.58), whole-body vibration, handling parts, and tool use, but poor for the other variables considered. Long-term reproducibility, from baseline or 1-year follow-up to 6-year follow-up, was poor for the composite index and almost all single items. UE MSD case status influenced 1-year test-retest reliability, with subjects who changed case status from baseline displaying higher reliability, but not reproducibility of recalled exposures. A strong regression to the mean effect was observed on exposures reported at follow-up surveys. CONCLUSIONS: Recalled ergonomics exposures could be employed in retrospective cohort studies as a somewhat reliable and unbiased estimate of the self-reported exposures that would have been obtained up to one year earlier, but not over a longer period (5-6 years). These longer-term results may have been limited by difficulty in matching jobs between interviews; also the regression to the mean effect likely contributed to reduce agreement. Changes in production technology and work organization produced a decrease in physical workload intensity and job pace, but did not have a substantial impact on an exposure index for the upper limb.

Automobiles↗

PubMed2005

Effect of passive stretch on reproducibility of hip range of motion measurements.

OBJECTIVE: To examine the intra- and intertester and intra- and interday reliability of hip passive range of motion (PROM) measurements and the effect of passive stretch on the reproducibility of PROM measurements. DESIGN: Reliability study. SETTING: Rehabilitation clinic at university hospital. PARTICIPANTS: Twenty volunteers (12 women, 8 men; age range, 18-45 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Two physical therapists made 2 PROM measurements on the first day and repeated them once after 2 days. The PROM in hip flexion, extension, and inner rotation and knee flexion were determined. The measurements of the hip flexion and inner rotation involved either 1 or 8 short-term passive stretches. The reproducibility was expressed as the intraclass correlation coefficient (ICC) and the coefficient of variation (CV) (in percent). RESULTS: The passive stretch increased significantly ( P <.05 to P <.001) the PROM of the hip joint. The reproducibility of the PROM measurement did not increase after repetitive passive stretch. The intra- and interday intra- and intertester ICC and CV of the PROM of the hip flexion and hip inner rotation ranged from .655 to .988 and 2.1% to 12.6%, respectively. The intra- and intertester intra- and interday ICC of the PROM of the hip extension ranged from .740 to .961, and the CV ranged from -85.5% to 242.6%. The intra- and intertester intra- and interday ICC of the PROM of the knee flexion ranged from .497 to .913, and the CV ranged from 2.5% to 9.9%. CONCLUSIONS: Repetitive stretching increased significantly the PROM in hip flexion and inner rotation, but the reproducibility of the PROM measurement did not improve. The hip flexion and the hip inner rotation PROM measurements had moderate to very high intra- and interday intra- and intertester reliabilities. The reliability of the PROM in hip extension and knee flexion was poor.

Adult↗

PubMed2006

Modulation of corticospinal excitability by paired associative stimulation: reproducibility of effects and intraindividual reliability.

OBJECTIVE: Electrical stimulation of the median nerve followed by a magnetic pulse on the primary motor cortex (M1) is effective to cause an increase in the amplitude of motor evoked potential (MEP) registered in the target muscle with the interstimulus interval (ISI) at 25ms (paired associative stimulation, PAS). The aim of this study is to evaluate the reproducibility of PAS with ISI 25 (PAS25), assessed in two separate sessions. Intraindividual reliability of TMS measures was also evaluated. METHODS: Motor threshold of abductor pollicis brevis (APB), assessed at rest, and MEP amplitude of APB and abductor digiti minimi (ADM) were assessed before and after PAS25 in 18 healthy volunteers (nine males and nine females). RESULTS: Data showed a significant increase of MEP amplitude in the target muscle (APB) after PAS25 and a reproducibility of group effect in the two sessions, as assessed by ANOVA, but a lack of intraindividual reliability, as assessed by intraclass correlation coefficients (ICC). CONCLUSIONS: The results underline the reproducibility of mean effects and the need to be careful when comparing the same subject on different days. SIGNIFICANCE: Electrical stimulation of the median nerve followed by a magnetic pulse delivered on M1 after 25ms causes a reproducible increase in MEP amplitude, without showing an acceptable intraindividual reliability.

Abducens Nerve↗

PubMed2005

Reproducibility of the spectral components of the electroencephalogram during driver fatigue.

OBJECTIVE: To date, no study has tested the reproducibility of EEG changes that occur during driver fatigue. For the EEG changes to be useful in the development of a fatigue countermeasure device the EEG response during each onset period of fatigue in individuals needs to be reproducible. It should be noted that fatigue during driving is not a continuous process but consists of successive episodes of 'microsleeps' where the subject may go in and out of a fatigue state. The aim of the present study was to investigate the reproducibility of fatigue during driving in both professional and non-professional drivers. METHODS: Thirty five non-professional drivers and twenty professional drivers were tested during two separate sessions of a driver simulator task. EEG, EOG and behavioural measurements of fatigue were obtained during the driving task. RESULTS: The results showed high reproducibility for the delta and theta bands (r>0.95) in both groups of drivers. CONCLUSIONS: The results are discussed in light of implications for future studies and for the development of an EEG based fatigue countermeasure device.

Adult↗

PubMed2004

Month-to-month and year-to-year reproducibility of high frequency QRS ECG signals.

High frequency electrocardiography analyzing the entire QRS complex in the frequency range of 150 to 250 Hz may prove useful in the detection of coronary artery disease, yet the long-term stability of these waveforms has not been fully characterized. Therefore, we prospectively investigated the reproducibility of the root mean squared voltage, kurtosis, and the presence versus absence of reduced amplitude zones in signal averaged 12-lead high frequency QRS recordings acquired in the supine position one month apart in 16 subjects and one year apart in 27 subjects. Reproducibility of root mean squared voltage and kurtosis was excellent over these time intervals in the limb leads, and acceptable in the precordial leads using both the V-lead and CR-lead derivations. The relative error of root mean squared voltage was 12% month-to-month and 16% year-to-year in the serial recordings when averaged over all 12 leads. Reduced amplitude zones were also reproducible up to a rate of 87% and 81%, respectively, for the month-to-month and year-to-year recordings. We conclude that 12-lead high frequency QRS electrocardiograms are sufficiently reproducible for clinical use.

Adult↗

PubMed2005

Reproducibility of eight lower limb muscles activity level in the course of an incremental pedaling exercise.

Despite the wide use of surface electromyography (EMG) recorded during dynamic exercises, the reproducibility of EMG variables has not been fully established in a course of a dynamic leg exercise. The aim of this study was to investigate the reproducibility of eight lower limb muscles activity level during a pedaling exercise performed until exhaustion. Eight male were tested on two days held three days apart. Surface EMG was recorded from vastus lateralis, rectus femoris (RF), vastus medialis, semimembranosus, biceps femoris, gastrocnemius lateral, gastrocnemius medianus and tibialis anterior during incremental exercise test. The root mean square, an index of global EMG activity, was averaged every five crank revolutions (corresponding to about 3 s at 85 rpm) throughout the tests. Despite inter-subjects variations, we showed a high reproducibility of the activity level of lower limb muscles during a progressive pedaling exercise performed until exhaustion. However, RF muscle seemed to be the less reproducible of the eight muscles investigated during incremental pedaling exercise. These results suggest that each subject adopt a personal muscle activation strategy in a course of an incremental cycling exercise but fatigue phenomenon can induce some variations in the most fatigable muscles (RF).

Adaptation, Physiological↗

PubMed2004

Improving the reproducibility of hydrogel-coated glutamate microsensors by using an automated dipcoater.

Hydrogel-coated microsensors based on carbon fiber electrodes (CFEs) are promising tools for in vivo analysis of endogeneous compounds such as glutamate. However, their construction generally depends on manual fabrication, which often results in poor reproducibility. The aim of this study was to improve the reproducibility and performance of glutamate microsensors. CFEs (10 microm diameter, 300-500 microm long) were coated with a cross-linked redox-polymer hydrogel containing l-glutamate oxidase, horseradish peroxidase and ascorbate oxidase. Various parameters that are likely to influence the reproducibility of the glutamate microsensors were studied. It appeared that the most crucial step in determining the microsensor performance is the manual hydrogel-application procedure. To control this procedure an automated dipcoater was constructed, which allowed mechanical application of the hydrogel on the CFE under standardized conditions. Significant improvements in performance were seen when the CFEs were dipcoated for 10 min at 37 degrees C. Further improvements were obtained when the automated hydrogel application was combined with other cross-link methods, such as electrodeposition and electrostatic complexation. A crucial factor in determining the microsensor performance is the hydrogel thickness. Microscopic observations revealed that, despite the use of an automated dipcoater, the layer thickness was not constant. By combining the automated dipcoat technique with amperometry, the layer thickness could be indirectly monitored and controlled, which resulted in significant improvements of the reproducibility of the sensors.

Amino Acid Oxidoreductases↗

PubMed2005

Considerations in measuring cartilage thickness using MRI: factors influencing reproducibility and accuracy.

OBJECTIVE: The primary goal of this study was to describe and evaluate conditions that could influence the precision and accuracy of measuring in vivo cartilage thickness in the weight bearing regions of the knee from magnetic resonance imaging (MRI). DESIGN: Three-dimensional (3D) models of the femoral cartilage were created from segmented MR images. The weight bearing regions on femoral cartilage were selected for the portion of the tibiofemoral joint that sustains contact during walking. Six regions of interest (three on each condyle) were located on the femur. Average cartilage thickness was calculated over each region. The sensitivity of the precision of the measurements to observer variability was evaluated using intra- and inter-observer reproducibility tests of cartilage thickness measurements from the MRI-derived 3D models. In addition, the quantitative influence of a rule-based protocol for segmentation was evaluated using the inter-observer reproducibility protocol. Accuracy tests were conducted on porcine knees by comparing 3D models from MR images and laser scans across weight bearing and non-weight bearing regions. RESULTS: The precision was substantially better for the intra-observer tests (Coefficient of variation (CV) = 1-3%) than the inter-observer tests. Adding a rule-based protocol reduced variability in inter-observer tests substantially (CV = 6.6% vs 8.3%). Accuracy tests showed that the central and weight bearing regions on each condyle were more accurate than boundary and non-weight bearing regions. In addition, these results indicate that care should be taken when determining cartilage thickness of weight bearing regions with cartilage degenerations, since the thickness of thinner cartilage can be systematically overestimated in MR images. CONCLUSIONS: A rule-based approach can substantially increase inter-observer reproducibility when measuring cartilage thickness from multiple observers. This improvement in inter-observer reproducibility could be an important consideration for longitudinal studies of disease progression. In quantifying cartilage thickness, central and weight bearing regions on each condyle can provide more accurate measurement than boundary and non-weight bearing regions with average accuracy of +/-0.2-0.3 mm. An important finding of this study was that the weight bearing regions, which are usually of the greatest clinical interest, were measured most accurately by sagittal plane imaging.

Cartilage, Articular↗

PubMed2006

Reproducibility of contrast enhanced magnetic resonance renography in adolescents.

PURPOSE: We sought to determine the reproducibility of magnetic resonance imaging renography using 3 different mathematical models and 2 different approaches to convert the relative signal intensity into quantitative indices. Furthermore, we wanted to examine the influence of fluid intake on the obtained renal parameters. MATERIALS AND METHODS: A total of 10 healthy volunteers 13 to 16 years old were subjected to magnetic resonance imaging 3 times within 10 weeks, including an examination where fluid intake was increased. At each examination 0.1 mmol/kg gadolinium diethylenetriamine pentaacetic acid was administrated intravenously as a rapid bolus during a fast magnetic resonance renography sequence. Images were acquired in the coronal plan, and 1,200 images were recorded during approximately 7 minutes. Cortical data were analyzed to estimate absolute and differential function of renal parameters by converting signal intensities into quantitative units. RESULTS: Using the simple approach that a change in magnetic resonance imaging signal is linearly related to the change in gadolinium diethylenetriamine pentaacetic acid concentration, we found reproducibility in the range of 1% to 5% of all estimations of the differential renal function. The relative glomerular ultrafiltration (ml per minute per cm(3) kidney cortex) was calculated and a reproducibility of 7% was observed for relative glomerular ultrafiltration (using the model based on deconvolution). Increased hydration caused a significant change in most parameters. CONCLUSIONS: Contrast enhanced magnetic resonance renography is reproducible in the normal human kidney but excessive water intake has a significant influence on these parameters. Further studies are required to elucidate whether similar measurements can be applied to a kidney with impaired function.

Adolescent↗

PubMed2004

Induced sputum methodology: Validity and reproducibility of total glutathione measurement in supernatant of healthy and asthmatic individuals.

Glutathione (GSH), a major antioxidant, has repeatedly been linked to the pathogenesis of pulmonary disease. The measurement of GSH in induced sputum (IS) offers a noninvasive tool for the study and monitoring of oxidative stress in airway diseases. In this study we assessed the validity and reproducibility of GSH quantification in IS from healthy subjects and individuals with mild asthma. We spectrophotometrically quantified total GSH in the IS of 31 healthy nonsmoking volunteers and 12 individuals with mild asthma. IS was processed with varying concentrations of dithiothreitol (DTT) in an effort to evaluate the effect of DTT on GSH measurements. We performed spiking experiments with defined concentrations of GSH and quantified the percentage of recovery and also analyzed the effect of induction time on GSH levels through sequential sampling of sputum portions (15, 30, and 45 minutes' induction). Finally we tested the reproducibility of GSH measurements at 2 separate time points (0 and 72 hours) and expressed it as an intraclass correlation coefficient (R(i)) with a coefficient of reliability (CR). Processing with DTT increased GSH values in IS (P <.05 for each DTT concentration > 0.001%). Recovery of GSH after spiking was complete, with a mean recovery of 102% +/- 4.8%. Increasing duration of induction led to an increase in sputum GSH (15 minutes, 10.2 +/- 2.3 micromol/L; 30 minutes, 18.4 +/- 3.5 micromol/L; 45 minutes, 26.1 +/- 4 micromol/L; P <.05 for all comparisons). Reproducibility of sputum GSH both in healthy subjects and asthmatic individuals was good (R(i) =.78, P <.001; and R(i) =.51, P =.003, respectively). With the use of standardized protocols for duration of induction and sample processing, sputum GSH measurement in healthy subjects and asthmatic individuals is valid and reproducible.

Administration, Inhalation↗

PubMed2006

Reproducibility of odor maps by fMRI in rodents.

The interactions of volatile odorants with the approximately 1000 types of olfactory receptor neurons in the olfactory mucosa are represented in the olfactory bulb by glomerular spatial activity maps. If these spatial maps underlie the perceptual identification of odorants then, for a given organism, they must be both specific and reproducible. However, this intra-organism reproducibility need not be present between organisms because genetic and developmental studies of olfactory bulb wiring suggest that there is substantial variation between the glomerular arrangements of closely related organisms and even between the two bulbs in a given animal. The ability of functional MRI (fMRI) to record responses of the entire rodent olfactory bulb repeatedly within the same subject has made it possible to assess the reproducibility of odor-induced spatial activity maps both within and between subjects exposed to equivalent stimuli. For a range of odorants, representing multiple chemical classes, a level of fMRI reproducibility (at 7.0 T and 9.4 T) comparable or superior to other cortical regions was demonstrated. While the responses of different bulbs to the same odorant could be localized within the same broad regions of the glomerular sheet, the precise magnitude and topology of the response within those regions were both often highly variable. These results demonstrate the robustness of high-field fMRI as a tool for assaying olfactory bulb function and provide evidence that equivalent perceptual outcomes may arise from divergent neural substrates.

Animals↗