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Results for “Reproducibility”

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At least 793 records · Page 44Linked to original sources

PubMed2000

[Study of the reproducibility of cardiac output measurement during exercise in pre-pubertal children by doppler echocardiography and CO2 inhalation].

Non-invasive measurement of the cardiac output is essential in investigations of healthy children. However, the data concerning the reproducibility of the measurements are very limited. The aim of this study was to assess the reproducibility of the measurement of cardiac output during exercise by Doppler echocardiography and reinhalation of CO2 (extrapolation method). Fourteen pre-pubertal children underwent two similar tests at increasingly intense levels of exercise. The cardiac output was measured at rest and during the last minute of each stepwise increment of exercise. The results show no difference between the cardiac outputs of the two tests, whichever method was used and at all levels of exercise. They also demonstrate a better reproducibility of cardiac output measurement by Doppler echocardiography (coefficient of variation: 7.5% at rest and 5.2% at maximal effort) compared with reinhalation of CO2 (coefficient of variation: 16.8% at rest and 11.7% at maximal effort). Both methods showed better reproducibility on exercise, resulting from smaller variations in heart rate and stroke volume on effort than at rest. The authors conclude that Doppler echocardiography is very accurate and its simplicity makes it the method of choice in pre-pubertal children for measuring cardiac output during exercise.

Carbon Dioxide↗

PubMed2002

Repeatability and reproducibility of macular thickness measurements with the Humphrey OCT system.

PURPOSE: To assess the accuracy, precision, repeatability, and reproducibility of measurements made by the Humphrey optical coherence tomography (OCT) system (Humphrey-Zeiss Medical Systems, San Leandro, CA). METHODS: The performance of the system was first investigated by scanning a test object containing an air gap of known size. Measurements were repeated with water or glycerin in the gap. In the clinical setting, macular thickness measurements were obtained from a control group of 20 normal subjects. For analysis, these scans were divided into eight sections, each containing 10 A-scans. RESULTS: The average gap thickness was found to be close to the true value in all cases. The overall coefficients of intersession reproducibility were less than 1% for the test object and 1.51% for the control group. There was no significant difference between scans acquired during different sessions. The overall coefficients of repeatability for the test object were between 0.2% and 1.1% and between 1% and 2% for the control group. The range of normal retinal thickness in terms of the 5th and 95th percentiles was 222 to 248 microm in women and 234 to 257 microm in men. CONCLUSIONS: Measurements made from OCT scans were found to be accurate and precise. Introducing water or glycerin into the test object resulted in considerable degradation of the signal, but measurements of gap thickness were still shown to be accurate, precise, reproducible, and repeatable. Retinal thickness measurements in the macular area were repeatable and reproducible. This demonstrates that OCT is a useful tool in the monitoring of patients with conditions that affect macular thickness, even when there is considerable degradation of the OCT signal.

Adult↗

PubMed2002

Evaluation of published clinical studies for reproducibility, comparability and adherence to evidence-based methods.

PURPOSE: To evaluate the "Materials and Methods" of long-term clinical studies in relation to documentation, reproducibility and comparability with and without employing the systematic methods of evidence-based medicine. MATERIALS AND METHODS: The "Materials and Methods" sections in 45 clinical long-term published studies of direct posterior resin-based composite restorations were evaluated for their use of systematic methods of evidence-based medicine. The search was limited to the years 1988-1997, using the key words "clinical study/evaluation/results/report, long-term, in vivo, posterior, Class I/II, composite, restoration". Special attention was directed to comparisons of the underlying documentation, descriptions of the operative techniques used, and their reproducibility. In addition, an evidence-based search was carried out using the Internet PubMed interface for MEDLINE, using identical synonyms, to identify studies with high levels of quality of evidence. Documentation, reproducibility, and comparability of "Materials and Methods" were also evaluated. RESULTS: Results revealed how difficult it is to interpret results based on tenuous premises, subjective standards, and inadequate study designs. Only one article could be identified when the search was limited to "humans" and "randomized clinical trials". None of the articles, even when fulfilling the highest quality of evidence, showed sufficient or satisfactory quality of reproducibility in their descriptions in Materials and Methods.

Clinical Trials as Topic↗

PubMed2002

Improving Gram-stained reproducible result by further adding clue cells in diagnosing bacterial vaginosis.

The reproducibility of interpretation in diagnosing bacterial vaginosis may be enhanced by adding pus cells and clue cells into two different criteria, developed by Spiegel et al. and Nugent et al. The purpose of study was designed to find out which parameter was more reproducible. 100 patients were collected with the diagnosis of bacterial vaginosis as an experimental group, while the other 100 patients who were with routine Papanicolaou smears in gynecologic clinic the collected as a control group. Two slides, including the original and reproducible ones, were obtained from vaginal smears for each patient. Three technicians read the slides randomly by using two different criteria, plus pus cells and clue cells. This showed the agreement for clue cells is the best method regardless of experimental group or control group (Kappa values between 0.708 and 1.000). The intra-observer agreement for the diagnosis of bacterial vaginosis by the method of Nugent et al. is superior to the method of Spiegel et al. Our data show the comparison of Amsel criteria versus Nugent criteria for the diagnosis of bacterial vaginosis with sensitivity of 88.9%, specificity of 55.4%, negative positive value of 62.1%, and positive predictive value of 85.8%. Moreover, our data also demonstrate the comparison of Amsel criteria versus the diagnosis either based on Nugent criteria or the presence of clue cells with sensitivity of 95.7%, specificity of 56.7%, negative positive value of 81.2%, and positive predictive value of 87.1%. The results demonstrate further adding score of the clue cells can enhance the reproducible diagnosis of bacterial vaginosis, which is superior to the methods of Nugent et al. and Spiegel et al.

Cytodiagnosis↗

PubMedDate not supplied

Peripapillary nerve fiber layer thickness measurement reproducibility using optical coherence tomography.

OBJECTIVE: To assess reproducibility of quadrantic and clock hour sectors of retinal nerve fiber layer thickness in normal eyes using optical coherence tomography. MATERIALS AND METHODS: Normal eyes of healthy volunteers meeting eligibility criteria were imaged by two inexperienced operators. Six 360 degrees circular scans with a diameter of 3.4 mm centered on the optic disc were obtained during each scanning session, and a baseline image was formed using 3 high-quality images defined by the software. Images were obtained on three different days within a 4-week period. Variance and coefficient of variation (CV) were calculated for quadrantic and retinal nerve fiber layer clock hour sectors obtained from the baseline image. RESULTS: Five normal eyes were scanned. Intraoperator reproducibility was high. The mean (+/- SD) CV for total retinal nerve fiber layer thickness was 5.3 +/- 3.82% and 4.33 +/- 3.7% for operators 1 and 2, respectively. Interoperator reproducibility was good with statistically similar variance for all quadrantic and clock hour retinal nerve fiber layer parameters (P = .42 to .99). The nasal retinal nerve fiber layer was the most variable sector for both operators (mean CV: 10.42% and 7.83% for operators 1 and 2, respectively). Differences in mean total, nasal, temporal, and superior retinal nerve fiber layer thickness were not statistically significant between operators for all eyes; however, for inferior retinal nerve fiber layer thickness, there was a significant (P = .0007) difference between operators in one eye. CONCLUSION: Peripapillary retinal nerve fiber layer thickness assessments using optical coherence tomography have good intraoperator and interoperator reproducibility. Inexperienced operators can generate useful measurement data with acceptable levels of variance.

Adult↗

PubMed2002

[Reproducibility of spiro-ergometric exercise test parameters in patients with heart failure].

UNLABELLED: The aim of the study was to determine the degree of reproducibility of parameters of cardiopulmonary exercise (CPX) tests in patients with chronic heart failure (HF). MATERIAL AND METHODS: We investigated 30 patients (7 women, 23 men) with ages ranging from 44 to 68 and a mean age of 56 +/- 14.5 years with HF due to dilated cardiomyopathy (5 patients) and coronary artery diseases (25 patients). The mean ejection fraction was 24 +/- 6.2%. All the patients were symptomatically stable during the preceding 4 weeks. After a preliminary test, the patients underwent two treadmill CPX tests using modified Naughton protocol with a 1-week interval between tests. CPX tests were performed at the same time of the day, using the same equipment and the patients were receiving constant medication. The reproducibility was assessed for: Rest heart rate (HRrest), oxygen uptake at the anaerobic threshold (VO2AT) and peak exercise (VO2peak), carbon dioxide production (VCO2peak), ventilatory equivalent of carbon dioxide (VE/VCO2peak) and oxygen (VE/VO2peak), end-tidal partial pressure for carbon dioxide (PETCO2peak), exercise time (T) and respiratory exchange ratio (RER). RESULTS: The reproducibility was found for all analyzed parameters of CPX tests: HRpeak (p < 0.0001), VO2AT (p < 0.0001), T (p < 0.001), HRpeak (p < 0.0001), VO2peak (p < 0.0001), VO2peak%N (p < 0.0001), VE/VCO2peak (p < 0.0001), VE/VO2peak (p < 0.0001), PETCO2peak (p < 0.0001), RER (p < 0.004). CONCLUSION: On adherence to standardized conditions, an excellent reproducibility exists for the most important parameters of cardiopulmonary exercise tests. CPX tests provide a useful and objective method of assessing functional capacity and diseases progression in patients with heart failure.

Adult↗

PubMed2003

Reproducibility of 11C-raclopride binding in the rat brain measured with the microPET R4: effects of scatter correction and tracer specific activity.

UNLABELLED: A new generation of commercial animal PET cameras may accelerate drug development by streamlining preclinical testing in laboratory animals. However, little information on the feasibility of using these machines for quantitative PET in small animals is available. Here we investigate the reproducibility of microPET imaging of (11)C-raclopride in the rat brain and the effects of tracer-specific activity and photon scatter correction on measures of D2 receptor (D2R) availability. METHODS: Sprague-Dawley rats (422 +/- 29 g; n = 7) were anesthetized with ketamine/xylazine and catheterized for tail vein injection of (11)C-raclopride. Each animal was positioned prone in the microPET, centering the head in the field of view. MicroPET data was collected for 60 min-starting at (11)C-raclopride injection-and binned into 24 time frames (6 x 10 s, 3 x 20 s, 8 x 60 s, 4 x 200 s, 3 x 600 s). In 3 studies, (11)C-raclopride was administered a second time in the same animal, with 2-4 h between injections. In a fourth animal, raclopride (1 mg/kg) was coinjected with (11)C-raclopride for the second injection. Three rats received a single dose of (11)C-raclopride. The range of doses for all studies was 6.11-18.54 MBq (165-501 micro Ci). The specific activity at injection was 4.07-48.1 GBq/ micro mol (0.11-1.3 Ci/ micro mol). Region-of-interest analysis was performed and the distribution volume ratio (DVR) was computed for striatum/cerebellum using sinograms uncorrected and corrected for scatter using a tail-fit method. RESULTS: Test-retest results showed that the (11)C-raclopride microPET DVR was reproducible (change in DVR = -8.3% +/- 4.4%). The average DVR from 6 rats injected with high specific activity (<4 nmol/kg) was 2.43 +/- 0.19 (coefficient of variation = 8%). The DVR for the blocking study was 1.23. The DVR depended on the mass of tracer (11)C-raclopride injected for doses >1.5 nmol/kg. Scatter fractions within the rat head were approximately 25%-45% resulting in an average increase of DVR of 3.5% (range, 0%-10%) after correction. CONCLUSION: This study shows that the (11)C-raclopride microPET-derived DVR is reproducible and suitable for studying D2R availability in the rat brain. MicroPET sensitivity was sufficient to determine reproducible DVRs from (11)C-raclopride injections of 9.25 MBq (approximately 250 micro Ci). However, the effect of tracer mass on the DVR should be considered for studies using more than approximately 1-2 nmol/kg raclopride, and scatter correction has a measurable impact on the results.

Animals↗

PubMed2003

An evaluation of the reproducibility of the measurement of the intima-media thickness of carotid arteries.

The intima-media thickness (IMT) of carotid arteries was demonstrated to be a reliable measure for early stages of atherosclerosis. B-mode ultrasound may be used to measure carotid IMT. The measurements of the IMT of the carotid artery (CA) conducted by different investigators can be comparable and enable the implementation of clinical trial successfully while maintaining a high reproducibility value. The objective of the study was to evaluate the reproducibility of the measurements made by the same investigator on two separate occasions (intraobserver variability) and the reproducibility of the off-line measurements between four sonographers in our laboratory (interobserver variability). The IMT of CA in 25 subjects (15 post stroke and 10 healthy persons) was investigated with the use of high-resolution ultrasonography. The CA subdivided into the common, bulbs and internal segments were scanned twice with a 3-week interval. Additionally three other readers with different levels of experience and skills in ultrasonography were asked to perform the same measurements in duplicate with at least a 3-week interval between. A high concurrence for intraobserver variability was detected with a correlation coefficient ranging from 0.92 to 0.95; p < 0.0001, and maximal bias 0.019 mm. Interobserver variability for all four readers also demonstrated a high correlation coefficient ranging from 0.72 to 0.83; p < 0.0001, and the maximal bias of measurements did not exceed 0.08 mm. The analogue measurements performed by the team demonstrate a reliable reproducibility in terms of the results of morphologic measurements. The differences obtained in the study were less than the error of the method (i.e. 0.1 mm) and should not influence clinical decision-making. Additionally, this study demonstrated that interobserver concurrence increases with the increasing experience of the investigators.

Aged↗

PubMed1992

Reproducibility of childhood respiratory symptom questions.

The reproducibility of answers to childhood respiratory symptom questions was investigated by administering two childhood respiratory symptom questionnaires twice, with a one month interval, to the same population of Dutch school children. The questionnaires were completed by the parents of 410 children from 6-12 yrs old. One questionnaire was developed by the World Health Organization (WHO). The other questionnaire was developed for use by school health services and was based mainly on the American Thoracic Society (ATS) questionnaire for respiratory symptoms in childhood. It was called the Child Health Care (CHC) Questionnaire. Half of the parents received a questionnaire in which the WHO questions came first on both occasions, the other half a questionnaire in which the CHC questionnaire came first on both occasions. The reproducibility of the answers was assessed by calculating Cohen's Kappa, a chance-corrected measure of association. Questions about "wheeze", "asthma", "bronchitis", "cough and phlegm", and "pneumonia" were found to give good to excellent reproducibility, with Kappa values ranging from 0.60-0.96. Questions about "phlegm", "cough", "chest congestion" and "runny/congested nose" were less satisfactory in this respect, with Kappa values generally well below 0.60. The reproducibility of the answers did not depend on the order in which the questionnaires were administered, on the gender or age of the child, or on the smoking habits or educational level of the parents.

Child↗

PubMed2003

Bristle end rounding of manual toothbrushes and reproducibility of end rounding classification.

PURPOSE: To evaluate the bristle end rounding quality of the toothbrushes selected. Furthermore the reproducibility of the bristle tip classification method was assessed. METHODS: Fifteen different manual toothbrushes were examined by taking into account the traumatic potential of toothbrushing caused by sharp and edged bristle end geometry. Three brushes for young children (0-4 years of age), eight brushes for children of 5-14 years of age and four brushes for juveniles and adults were included. The macroscopic criteria to which the selected brushes had to conform were: a compact toothbrush handle, a small brush head with rounded contours and a medium or soft bristle stiffness. Bristle tip geometry was investigated under SEM according to a modified scale by Silverstone & Featherstone. End rounding was examined in five regions equally distributed over the brush head. Two brushes of each brand were included in the SEM investigation. For evaluation of reproducibility , end roundings of 119 bristle tips were assessed twice by one experienced examiner and once by two additional unexperienced examiners. RESULTS: The proportion of acceptably rounded bristle tips varied widely from 65.2 - 99%. Half of the products examined achieved a level of at least 90% acceptable bristle end rounding. Five of the toothbrushes examined had between 70 and 90% acceptable bristle end geometries, while two products had less than 70%. Intraindividual reproducibility regarding acceptable and unacceptable end rounding was 99.16%, interindividual reproducibility varied between 90.76% and 94.96%.

Adolescent↗

PubMed2003

A system for the acquisition of reproducible digital skin lesions images.

A major issue concerning the design and implementation of an image acquisition system for skin lesions is its ability to capture reproducible images. The reproducibility is considered essential for image analysis and for the comparison of sequential images during follow-up studies. This paper describes a prototype image acquisition system that includes a standardized illumination and capturing geometry with polarizing filters and a series of software corrections: Calibration to Black, White and Color for color constancy, Internal camera Parameters adjustment and Pose extraction for stereo vision, Shading correction and Noise Filtering for color quality. The validity of the calibration procedure and the images' reproducibility were tested by capturing sample images in three different lighting conditions: dark, medium and intense lighting. For each case the average values of the three color planes RGB and their standard deviations were calculated; the measured error differences ranged between 0.7 and 12.9 (in the 0-255 scale). Preliminary experiments for stereo measurements provided repeatability of about 0.3 mm. The above results demonstrate the reproducibility of the captured images at a satisfactory level. The developed prototype was also evaluated clinically, for its ability to support the construction of knowledge-based decision systems and for telemedicine, thus to support telemedical sessions in dermatology.

Greece↗

PubMed2004

Reproducibility of 99mTc-TRODAT-1 SPECT measurement of dopamine transporters in Parkinson's disease.

UNLABELLED: Functional brain imaging targeting the presynaptic dopamine nerve terminal of the nigrostriatal system has been used for monitoring disease progression and evaluating therapeutic effectiveness in patients with Parkinson's disease (PD). (99m)Tc-TRODAT-1 binds with high selectivity to the dopamine transporters in the striatum and can be imaged with SPECT 4 h after injection. We studied the test and retest reproducibility of (99m)Tc-TRODAT-1 SPECT measures in patients with PD to assess the reliability of (99m)Tc-TRODAT-1 for longitudinal evaluation of the nigrostriatal dopaminergic function. METHODS: Each of 20 patients with PD underwent 2 (99m)Tc-TRODAT-1 SPECT scans at an interval of 2-3 wk. Patients were imaged 4 h after injection of 925 MBq (99m)Tc-TRODAT-1. Two imaging outcome measures were evaluated: the ratio of specific-striatal-to-nonspecific uptake and the striatal asymmetry index. For both measures, the test/retest variability was calculated. Reproducibility of the 2 outcome measures was evaluated in terms of intraclass correlation coefficient (ICC) and 95% limits of agreement. RESULTS: The mean ratio of specific-striatal-to-nonspecific uptake showed excellent test/retest reproducibility with a mean variability of 10.20%, an ICC of 0.95 (95% confidence interval = 0.88-0.98), and 95% limits of agreement, ranging from -0.19 to 0.19. The striatal asymmetry index had larger test/retest variability (60.41%), a slightly smaller ICC of 0.86 (95% confidence interval = 0.65-0.95), and a wider range of 95% limits of agreement (-16.09 to 15.19). In addition, there was a significant negative correlation between the mean ratio of specific-striatal-to-nonspecific uptake and the motor subscore of the Unified Parkinson's Disease Rating Scale in both test and retest conditions. CONCLUSION: Our data indicate that the imaging outcome expressed by the mean ratio of specific-striatal-to-nonspecific uptake has an excellent test/retest reproducibility and correlates with disease severity. These findings suggest that (99m)Tc-TRODAT-1 SPECT imaging is useful and feasible for measuring disease progression in PD.

Brain↗

PubMedDate not supplied

Intraobserver reproducibility of retinal nerve fiber layer measurements using scanning laser polarimetry and optical coherence tomography in normal and ocular hypertensive subjects.

PURPOSE: To evaluate quantitatively the intraobserver reproducibility of measurements of the retinal nerve fiber layer (RNFL) in healthy subjects and an ocular hypertensive population using two nerve fiber analyzers. METHODS: Sixty eyes of normal (n=30) and ocular hypertensive subjects (n=30) were consecutively recruited for this study and underwent a complete ophthalmologic examination and achromatic automated perimetry. RNFL were measured using scanning laser polarimeter (GDx-VCC) and optical coherence tomography (OCT Model 3000). Reproducibility of the RNFL measurements obtained with both nerve fiber analyzers were compared using the coefficient of variation. RESULTS: In both groups the authors found fair correlations between the two methods in all ratio and thickness parameters. The mean coefficient of variation for measurement of the variables ranged from 2.24% to 13.12% for GDx-VCC, and from 5.01% to 9.24% for OCT Model 3000. The authors could not detect any significant differences between healthy and ocular hypertensive eyes, although in normal eyes the correlations improved slightly. Nevertheless, the test-retest correlation was slightly better for GDx-VCC than for OCT Model 3000 (5.55% and 7.11%, respectively). CONCLUSIONS: Retinal mapping software of both nerve fiber analyzers allows reproducible measurement of RNFL in both healthy subjects and ocular hypertensive eyes, and shows fair correlations and good intraobserver reproducibility. However, in our study, GDx showed a better test-retest correlation.

Adult↗

PubMed2006

PET imaging of serotonin transporters with [11C]DASB: test-retest reproducibility using a multilinear reference tissue parametric imaging method.

UNLABELLED: Parametric imaging of serotonin transporters (SERT) with 11C-labeled 3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)benzonitrile ([11C]DASB) PET is a useful data analysis tool. The purpose of this study was to evaluate the reproducibility of measurements of SERT binding potential (BP) and relative blood flow (R1) by a 2-parameter multilinear reference tissue parametric imaging method (MRTM2) for human [11C]DASB studies. METHODS: Eight healthy subjects (3 men, 5 women; age, 26 +/- 9 y) underwent 2 [11C]DASB PET scans separated by 1 h on the same day (dose, 703 +/- 111 MBq). Parametric images of BP and R1 were generated by MRTM2 using the cerebellum as a reference region. The k'2 (clearance rate constant from the reference region) required by MRTM2 was estimated by the 3-parameter MRTM. Reproducibility of BP and R1 measurements was evaluated by calculating bias (100 x (retest - test/test), variability (SD of the bias), and reliability (intraclass correlation coefficient = rho) for several representative regions of interest (ROIs). BP and R1 were estimated for ROI time-activity curves fitted by MRTM2 and were compared with those based on the parametric images. RESULTS: The test-retest (0.066 +/- 0.013/0.06 +/- 0.011 min(-1)) MRTM k'2 reproducibility was excellent with small bias (3%) and variability (6%) and high reliability (0.95). Retest BP values were consistently lower than those of test BP values in all regions (a mean negative bias of approximately 6%; P < 0.001). The test-retest BP variability was relatively small, ranging from 4% to 13%, with rho ranging from 0.44 to 0.85. In contrast to BP, test-retest R1 values were similar with negligible bias of < or =0.1%. The test-retest R1 variability was excellent and smaller than that of BP ranging from 3% to 6%, with rho ranging from 0.58 to 0.95. BP and R1 values estimated by the ROI time-activity curve-fitting method were slightly lower ( approximately 3% and approximately 1%, respectively) than those by the parametric imaging method (P < 0.001). However, the test-retest bias and variability of BP and R1 were very similar for both ROI and parametric methods. CONCLUSION: Our results suggest that [11C]DASB parametric imaging of BP and R1 with the noninvasive MRTM2 method is reproducible and reliable for PET studies of SERT.

Adult↗

PubMed2005

Reproducibility of retention time using a splitless nanoLC coupled to an ESI-FTICR mass spectrometer.

Replicate injections of a myoglobin tryptic digest, ultrafiltrates of human serum, and ultrafiltrates of human plasma made on a splitless nanoscale liquid chromatography system coupled to a Fourier-transform ion cyclotron resonance mass spectrometer were utilized to assess analytical reproducibility. The mean (across 19 tryptic fragments detected in at least 3 of 24 replicate injections) of the 95% CIM of retention time is +/-6.3 sec and the maximum is +/-11.6 sec; when only those tryptic fragments that were found in 24 of 24 replicates are considered, the maximum 95% CIM of retention time drops to +/-6.7 sec. This represents a deviation of at most seven spectra. Similarly, in the serum (and plasma) filtrates, 95% of the 393 (312) species observed in 3 replicate injections had a 95% CIM of retention time of +/-22.0 (+/-18.5) sec or less. Ion abundance was similarly reproducible, with an average across those tryptic fragments observed in all 24 replicates of the coefficient of variation of ion abundance equal to 37.0%. This reproducibility represents a significant improvement over prior work, which required flow splitting in order to achieve nanoliter-per-minute flow rates. These improvements in retention time reproducibility will also be observed with mass spectrometers employing mass analyzers other than FT-ICR.

Case-Control Studies↗

PubMed2006

Stability of IGF-I concentration despite divergent results of repeated GH stimulating tests indicates poor reproducibility of test results.

OBJECTIVE: Growth hormone (GH) secretion is routinely assessed in provocative tests. However, some limitations of these tests have been reported, including a weak correlation between spontaneous GH secretion and GH peak in stimulating tests, poor reproducibility of test results and normalisation of previously decreased GH response to stimulation in the repeated provocative tests. The observed discrepancies between the results of consecutive GH stimulating tests in the same patient may be explained either by real changes in GH secretion or by the poor reproducibility of GH response to stimulation. Normalisation of previously decreased GH secretion should entail the increase of insulin-like growth factor-I (IGF-I) concentration, while stability of IGF-I secretion despite divergent GH response to stimulation in repeated tests might indicate the poor reproducibility of GH stimulating tests. continue with The aim of the study was a comparison of GH peak in repeated stimulating tests and of corresponding, simultaneously measured IGF-I concentration. METHODS: The investigation comprised 84 children with short stature who underwent repeated GH tests and IGF-I evaluation. In 60 patients each of two different tests (with clonidine and with glucagon, in standard doses) was performed twice, together with IGF-I measurement during both evaluations. In 20 patients (remaining in the same pubertal stage during the time period between the procedures in question) at least one test, together with IGF-I measurement, was repeated within one year. RESULTS: The correlation between the results of GH tests, repeated during the two evaluations, was weak (r=0.22, p<0.05 for all patients and r=0.25, p<0.05 for the patients examined 2 times within 1 year), with the high within-subject variability (43.4 % and 59.5 %, respectively). Conversely, the correlation between two values of IGF-I SDS was good both for all patients (r=0.65, p<0.05) and especially for the patients examined twice within 1 year (r=0.96, p<0.05), with low within-subject variability for the latter subgroup of patients (11.2 %). The same GH stimulating tests, performed twice in the same patient, led to different conclusions (either the confirmation of GHD diagnosis or its exclusion) in most of examined patients. Poor reproducibility of GH stimulating tests, rather than the possibility of short-term changes in GH secretion, was confirmed.

Adolescent↗

PubMed1991

[Reproducibility of three-dimensional point by point measurements on the optic nerve head surface using a computerized image analysis system].

The reproducibility of topographic measurements of the optic nerve head was studied using a prototype Humphrey Retinal Analyzer system (Allergan Humphrey SKB, San Leandro, CA). Digital simultaneous stereographic images were obtained using programs in the Analyzer. The analyzer expressed the results in terms of microns of elevation at approximately 300 locations on the optic nerve head surface. At least 3 separate stereoscopic digital images were made of each of 8 eyes of 5 subjects. One randomly selected image of each disc was analyzed twice in order to determine intra-image reproducibility, and topographic analyses of two randomly selected images of each disc were compared to estimate the inter-image variability. We calculated the coefficients of variation (CV) of measurements at the center point of the optic disc. Further, we computed the absolute value of the difference in the degree of elevation among the measured locations on the optic disc and calculated the median and 95 percentile value of that group of approximately 300 differences. The CV, medians, and the 95 percentile values thus obtained for the 8 discs ranged from 0 to 6.1%, from 6 to 20 microns, and from 20 to 69 microns, respectively for intra-image reproducibility. Those for inter-image reproducibility ranged from 1.5 to 59.1%, from 6 to 33 microns, and from 36 to 92 microns, respectively.

Humans↗

PubMed1991

[Problems of the reproducibility of the inhaled dosage exemplified with the Pari provocation test I apparatus].

The unspecific bronchial provocation test--usually performed with histamine, metacholine or carbachol--is used to determine whether bronchial hyperreactivity is present, and to what degree. Epidemiological studies have shown, that an overlap exists between "healthy" and "sick". There are several reasons for this, the most important being the insufficient reproducibility of intrabronchial deposition and the fact that the total provocation dose is often unknown. The following factors must be taken into account to improve this situation: 1. Only those devices where the particle spectrum is not influenced by the inspiration flow (without additional airstream) should be used to produce aerosols. 2. The air current containing aerosols is vapour saturated when liquid aerosols are produced. As the vapour is derived from the nebulizing solution it forms part of the weight or volume loss, this can be up to 50% of the total weight/volume loss. The aerosol output is far more constant and practically independent of the vapour saturation and the temperature. The intrabronchial dose can therefore not be calculated according to the weight loss of the nebulizer, as this is incorrect. 3. The evaporation of the nebulizing solution leads to an increase in the concentration of the test substance, especially towards the end of the evaporation process. Thus, the volume of the nebulizing solution should always be as large as possible or renewed early. 4. The slower the inhalation maneuver, the less the reproducibility of the intrabronchial deposition is impaired. The intrabronchial deposition varies least, when a slow inspiratory vital capacity maneuver is carried out (inspiration time greater than 8 s). Exhalation should be normal or even rapid, as aerosol deposition is thus increased, due to airway collapse. Breath-holding at the end of inspiration, for about 3-4 seconds, is favourable. 5. The anatomy of the glottic region varies greatly interindividually, influencing intrabronchial deposition. To reduce this to a minimum, the average diameter of the particles should not exceed 2 microns. On the other hand, the diameter of particles should not be under 1 micron, as the inhaled amount of substance is then markedly reduced (volume approximately d3). 6. Reservoirs, storaging the aerosol before inhalation, increase reproducibility, since they stabilize the aerosol due to vapour saturation. Plastic reservoirs must either be of antistatic material, or made antistatic by being filled repeatedly. The reproducibility of intrabronchial deposition is in the range of +/- 15% for the PARI-Provokationstest device I, (determined by radioactive labelling).(ABSTRACT TRUNCATED AT 400 WORDS)

Aerosols↗