A collaborative study on the repeatability and the reproducibility of the Dutch standard-suspension-test for the evaluation of disinfectants.
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Candida albicans↗
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Results for “Repeatability and Reproducibility”
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The reproducibility of reported height and body weight in repeated questionnaire surveys.
Reproducibility of reported height and weight were studied via repeated questionnaire surveys distributed to subjects within a year. Effects of the factors which might influence the reproducibility of these values were investigated. Although only about half of the subjects reported the same height and 30% the same weight on the second questionnaire, no change was found in average height and weight after a one year interval for both male and female subjects. The reproducibility decreased with age for both height and weight. Smokers tended to have lower reproducibility for height than non-smokers. The shorter subjects had lower height reproducibility than their taller counterparts, while heavier subjects had lower weight reproducibility than light subjects. It was observed that the lower the weight reproducibility, the lower the height reproducibility and vice versa. Reported height or weight figures ending in zero or five were more frequent than the expected 10% with low reproducibility.
Adult↗
Method validation for strobilurin fungicides in cereals and fruit.
Strobilurins are a new class of fungicides that are active against a broad spectrum of fungi. In the present work a GC method for analysis of strobilurin fungicides was validated. The method was based on, extraction with ethyl acetate/cyclohexane, clean-up by gel permeation chromatography, (GPC) and determination of the content by gas chromatography (GC) with electron capture (EC-), nitrogen/phosphorous (NP-), and mass spectrometric (MS-) detection. Three strobilurins, azoxystrobin, kresoxim-methyl and trifloxystrobin were validated on three matrices, wheat, apple and grapes. The validation was based on recovery tests at three or four spiking levels, determined as double determinations and repeated three times (n = 6). The mean recoveries for the three detectors were in the range of 70-114%, and the LODs were between 0.004 mg/kg and 0.014 mg/kg, for all three strobilurins. The values for repeatability and reproducibility were within the limits for repeatability and reproducibility given by the Horwitz equation. Validation was not accepted for azoxystrobin in grapes on all three detectors and for azoxystrobin in apple for the MS-detector. A comparison of matrix-matched standards versus standards in solvent showed varying differences between the two calibration curves.
Acrylates↗
Repeated drought induces a reproducible DNA methylation response associated with gene expression in Quercus lobata.
UNLABELLED: Long-lived trees must continually adjust to environmental change and face sustained climatic shifts over their lifetimes. One increasingly important challenge is the rising frequency of drought caused by climate change. Environmentally responsive DNA methylation is widespread in plants, but whether it contributes to gene expression during environmental stress remains unclear, particularly in long-lived trees. Here, we integrated long read methylomes and transcriptomes from valley oak ( Quercus lobata ) seedlings exposed to repeated drought and well-watered treatments. Repeated drought induced a reproducible DNA methylation response that repeatedly targeted the same genomic regions despite turnover of individual methylated sites. These repeatedly targeted regions were transposable elements (TEs) located near genes. Genes adjacent to CHH-methylated TEs were enriched for core drought-response pathways, including abscisic acid signaling, osmotic adjustment and cell-wall remodeling, and remained transcriptionally activated under drought. However, higher CHH methylation levels were associated with progressively smaller transcriptional responses, suggesting that environmentally responsive DNA methylation influences how strongly drought- response genes are activated rather than simply switching them on or off. At the same time, greater CHH methylation was associated with continued repression of nearby TEs, suggesting that this response may simultaneously regulate gene activity while maintaining genome stability. Together, these findings identify a reproducible genome- regulatory response associated with repeated environmental stress in a long-lived tree. By repeatedly targeting the same genomic regions despite turnover of individual sites, this response provides a framework for how long-lived trees repeatedly adjust gene expression while maintaining genome stability during environmental change. SIGNIFICANCE STATEMENT: Plants cannot escape environmental change, and trees must repeatedly respond to stresses, such as drought, over lifetimes spanning decades to centuries. Yet little is known about the molecular mechanisms that make this remarkable resilience possible. Using a widespread California oak, we show that repeated drought repeatedly induced the same DNA methylation pattern in the same parts of the genome, even though the differentially methylated individual sites changed between drought events. This pattern was linked to how strongly drought-response genes were activated, suggesting that trees repeatedly deploy the same molecular program to respond to environmental stress. Our findings provide a new framework for understanding how long-lived organisms repeatedly adjust to changing climates.
Journal Article↗
Skin prick tests to common allergens in adult atopic eczema and rhinitis patients: reproducibility on duplicate and repeated testing.
Skin prick test reactivity to a battery of common allergens was examined in 26 adults with atopic eczema, in 9 patients with allergic rhinitis and in 10 nonatopic controls. In both patient groups, reactivity was most frequent for grass pollen, followed by rye, house dust mite, tree and herb, with no reactions to food allergens. Repeated tests at weekly intervals were less reproducible in weak reactions and in severely affected eczema patients compared to those lightly affected. Skin prick tests are therefore reliable and reproducible in atopics and provide means to counsel patients on avoidance of eliciting agents of their disease.
Adult↗
Repeated latex aeroallergen challenges employing a hooded exposure chamber: safety and reproducibility.
BACKGROUND: Bronchial, nasal, and conjunctival challenges are useful for clarifying discordant clinical history (Hx) and skin and/or serologic tests and in assessing semiquantitative changes in biologic sensitivity over time. The objective of this study was to determine the safety and reproducibility of repeated latex-allergen challenges with a hooded exposure chamber (HEC). METHODS: The HEC system comprises a powered forced-air respirator with a fitted face shield and hood that uses glove-derived latex-allergen associated cornstarch particles (LAC) to expose simultaneously the conjunctiva, nose, and lungs. Serial control and incremental LAC challenges are conducted until an endpoint based on upper and/or lower respiratory tract symptoms and peak expiratory flow rates is reached. Six latex-allergic (Hx and puncture skin test [PST]- and 5/6 radioallergosorbent test [RAST]-positive) subjects were challenged on three separate occasions at least 2 weeks apart. Serial latex PST midpoints and serum anti-latex IgE by RAST were monitored at each visit and at a fourth follow-up visit. RESULTS: All subjects responded to LAC, but not to air or control cornstarch administered as controls. All responses were confined to mild symptoms of allergic rhinoconjunctivitis and/or asthma that either resolved spontaneously or were reversed with inhaled albuterol. No subject experienced a systemic or delayed reaction. There were no significant changes in the endpoint LAC doses over the three challenge visits (P>0.2). The mean coefficient of variation for log2 endpoints within-subjects was 17.3+/-17.2% (SD). The serum latex-specific IgE was not significantly boosted by the three challenges (P>0.2). The concentration of latex extract necessary to produce an 8-mm wheal by PST was not significantly changed during the study (P>0.1), indicating that latex sensitivity was not affected by the repeated LAC exposures. CONCLUSIONS: The results of this study indicate that repeated HEC latex-allergen challenges are both reproducible and safe, and do not increase latex sensitivity.
Administration, Inhalation↗
Reproducibility of the peritoneal equilibration test in CAPD patients.
A study was undertaken to evaluate the short-term reproducibility of peritoneal equilibration test (PET) results. Nine patients with end-stage renal disease undergoing continuous ambulatory peritoneal dialysis underwent PETs under similar conditions on 2 consecutive days. Dialysate samples were obtained at 0 hours, midcycle, and at the end of exchange. There were no significant differences between the mean ratios at 4 hours for creatine, urea nitrogen, potassium and protein, and glucose between PET 1 and PET 2. A standard PET is highly reproducible when repeated under similar conditions. Reproducibility is better for ratios of creatinine, glucose, urea nitrogen, and potassium than for protein.
Aged↗
Micro-laser-induced breakdown spectroscopy technique: a powerful method for performing quantitative surface mapping on conductive and nonconductive samples.
Laser-induced breakdown spectroscopy (LIBS) has been applied mainly to bulk analysis of solids, liquids, and gases and less frequently for elemental microanalysis of solid surfaces. A micro-LIBS device devoted to analysis of the distribution of elements on surfaces is described. This device offers rapid access with a 3-microm spatial resolution to the microchemical structures of both conductive and nonconductive samples. Quantitative microchemical results of applications to ceramics are reported. By the use of a time-resolved acquisition spectrum, cerium in a uranium matrix was characterized with a cerium detection limit of 1.14%. Calibration curves obtained with manipulations during 1 year facilitated evaluations of reproducibility and repeatability. A 2% single-shot repeatability with a calibration reproducibility of approximately 7% is reported.
Journal Article↗
Third metacarpal bone mineral density assessment in the standing horse by dual X-ray absorptiometry: suitability, precision and accuracy.
Bone mineral density (BMD) is correlated to mechanical properties of bone. In the horse, dual energy X-ray absorptiometry (DXA) has yet only been performed ex-vivo, but a new portable DXA device would be ideal for in-vivo BMD measurement. We explored field suitability, precision and accuracy of this device for in-vivo third metacarpal density assessment. Precision was analysed by calculating measurement variation under repeated measurement tests with (reproducibility) and without (repeatability) limb repositioning. Repeatability and reproducibility were tested ex-vivo, at the same time that intra- and inter-operator reproducibility were assessed in-vivo. In order to test accuracy, bone mineral content (BMC) of several bone samples determined by DXA and ashing were compared. Repeatability was 1.47% and reproducibility 1.69% ex-vivo. In-vivo reproducibility varied between 2.91 and 4.06% for intra-operator test and between 3.13 and 5.53% for inter-operator test. BMC measured by DXA and ash weight were highly correlated (R2>0.99). In conclusion, under described conditions this DXA device is usable, accurate and precise. Its sensitiveness reaches 8.23% in an individual longitudinal monitoring. Using the third metacarpal bone as an example, we have shown that this device is suitable for experimental or clinical monitoring.
Absorptiometry, Photon↗
Reproducibility of cytologic atypia in repeat nipple duct lavage.
BACKGROUND: It is believed that atypical cells identified by nipple duct lavage (NDL) indicate an increased risk for breast carcinoma similar to atypical ductal hyperplasia diagnosed by tissue biopsy, but many basic performance characteristics of NDL currently are undefined. METHODS: NDL was performed in 108 patients unselected for breast carcinoma risk and then was repeated after 2-14 months (median, 8 months) if the initial lavage was classified as atypical. Breast magnetic resonance images (MRIs) were obtained from a subset of patients who had atypical lavage results. RESULTS: Marked atypia was diagnosed in 22% of 36 breasts with an incident carcinoma compared with 7% of 172 unaffected breasts (P = 0.01). After excluding breasts with an incident carcinoma, there were 32 patients (30%) with either mild or marked atypia. The lavage was repeated in 23 of these women, and the second lavage was classified as atypical in 48%. Neither marked atypia on the initial lavage nor a 5-year Gail risk > or = 1.7% predicted atypia on repeat lavage, but there was a trend for improved reproducibility when the atypia initially was diagnosed in a fluid-producing duct. MRIs were abnormal in 13% of 24 breasts with an atypical lavage, and ductal carcinoma in situ was diagnosed subsequently in 1 breast. CONCLUSIONS: Atypia frequently is diagnosed by NDL, but the reproducibility of repeat lavage is low. Lavage atypia may be physiologic or artifactual rather than pathologic in many instances. Marked atypia occasionally may represent mammographically occult ductal carcinoma in situ.
Adult↗
Ultrasonographic assessment of regional radial and longitudinal systolic function in healthy awake dogs.
BACKGROUND: Strain (St) and strain rate (SR) imaging are new ultrasound modalities based on tissue Doppler imaging (TDI) that allow quantitative assessment of segmental myocardial contraction or stretching and rate of deformation, respectively. HYPOTHESIS: Regional peak systolic St and SR could allow repeatable and reproducible assessment of systolic function of the right (RVW) and left (LVFW) myocardial walls in dogs. ANIMALS: Six healthy Beagle dogs were used to determine the repeatability and reproducibility of regional peak systolic St and SR in the RVW and LVFW (Study 1). These variables were also assessed in 30 healthy dogs of several breeds (Study 2). METHODS: Longitudinal peak systolic St and SR were recorded in 2 segments (basal and apical) of the RVW and LVFW. Radial peak systolic St and SR of the LVFW were also assessed. RESULTS: All within- and most (7/10) between-day coefficients of variation were <15%. Absolute values of the longitudinal deformation indices were significantly higher (P < .001) in the RVW (St = -39.5 +/- 5.5% and SR = -5.2 +/- 0.8 s(-1) at the base; St = -36.3 +/- 4.3% and SR = -4.7 +/- 1.1 s(-1) at the apex) than in the LVFW. Absolute values were also higher for the radial (St = 62.9 +/- 10.4% and SR = 5.8 +/- 1.1 s(-1), P < .001) than for the longitudinal LFVW motions. CONCLUSIONS AND CLINICAL IMPORTANCE: St and SR imaging is a repeatable and reproducible method for assessing systolic myocardial function. The combination of these indices with conventional echocardiographic variables may be useful for screening canine myocardial diseases.
Animals↗
Reproducibility of antibiogram of bovine mammary gland staphylococci under conditions of repeated subculturing.
The reproducibility of antibiogram profiles of 10 staphylococcal isolates of bovine mammary gland origin was tested under conditions of repeated subculturing. Prototype (original or index) antibiogram profiles were determined by subculturing these isolates from stock cultures stored at -70 degrees C. The isolates were then subcultured four times on blood agar and antibiogram profiles determined at each subculture on Mueller-Hinton agar. The antibiogram profiles of each isolate at each subculture were compared with the prototype profiles of that isolate. At repeat antibiogram determinations, deviations of < or = 5 mm in the individual zones of inhibition of penicillin, ampicillin and streptomycin from the prototype antibiogram profiles, resulted in a shift of only three isolates from the resistant to intermediate and one isolate from intermediate to resistant status of antibiotic susceptibility classification. It is suggested that in the interpretation of antibiogram, susceptibility classification (resistant, intermediate, or susceptible) variations accruing from a few millimetres differences in the diameter of the zones of inhibition should probably be disregarded.
Ampicillin↗
Forearm cephalic vein cross-sectional area changes at incremental congestion pressures: towards a standardized and reproducible vein mapping protocol.
OBJECTIVES: Duplex ultrasonography assessment of superficial forearm veins is frequently used before a hemodialysis arteriovenous fistula (AVF) is created. There is, however, no standardized preoperative duplex ultrasonography protocol. This study assessed B-mode image analysis reproducibility and reproducibility of repeated forearm superficial venous diameter measurements on different days at different venous congestion pressures (VCPs). METHODS: Diameters were determined using B-mode ultrasonography in 10 healthy male volunteers on days 1 and 14 at incremental VCP values (10 to 80 mm Hg). Intra- and interobserver agreement was assessed for B-mode image analysis by calculating interclass correlation coefficients (ICC). Reproducibility of repeated diameter measurements (maximum and minimum diameter at days 1 and 14), cross-sectional area size increase, and shape change due to incremental VCPs were determined by calculating ICC values. RESULTS: Analysis of intraobserver agreement of B-mode image interpretation yielded ICC values of 0.97 (95% confidence interval [CI], 0.94 to 0.99) and 0.97 (95% CI, 0.96 to 0.99) for determination of maximum and minimum diameters, respectively. Interobserver agreement analysis yielded ICC values of 0.95 (95% CI, 0.92 to 0.97) and 0.96 (95% CI, 0.96 to 0.99) for determination of maximum and minimum diameters, respectively. Reproducibility of repeated diameter measurements on days 1 and 14 improved substantially at incremental VCP values, with best reproducibility at VCPs >40 mm Hg. Repeated determination of cross-sectional area size increase and shape change due to VCP increase from 10 to 80 mm Hg yielded ICC values of 0.49 (95% CI, 0.19 to 1.00) and 0.09 (95% CI, 0.00 to 0.92), respectively. Maximum and minimum diameters as well as cross-sectional area size increased significantly (P < .01) due to VCP increase during both sessions. Cross-sectional area shape changed significantly (P < .01) due to VCP increase during both sessions. CONCLUSIONS: Diameter measurements on B-mode images are largely observer independent. Superficial venous cross-sectional area shape is noncircular, and cross-sectional area size depends on VCP. Both maximum and minimum venous diameters should be determined at VCPs >40 mm Hg to attain the best reproducibility. Further studies are needed to determine whether a standardized preoperative vein mapping protocol can reduce AVF nonmaturation rates.
Adult↗
Quality control in health care: an experiment in radiotherapy planning for breast cancer patients after mastectomy.
PURPOSE: The importance of evaluating and improving quality in clinical practice is now generally acknowledged. In this study we estimated different sources of variation in radiotherapy planning for breast cancer patients after mastectomy and sought to test the applicability of a reproducibility and repeatability (R&R) study in a clinical context. METHODS: Eleven radiation oncologists planned radiotherapy three times for three different kinds of breast cancer patients without knowing they were handling the same patient three times. Variation was divided into different components: physicians as operators, patients as parts, and repeated measurements as trials. Variation due to difference across trials (repeatability), that across the physicians (reproducibility), and that across the patients (variability) were estimated, as well as interactions between physicians and patients. Calculation was based on the sum of squares, and analysis was supported by various graphical presentations such as range charts and box plots. RESULTS: Some parts of the planning process were characterized by higher and different kinds of variation than the others. Interphysician variation (i.e., reproducibility) was not high but there were some clearly outlying physicians. The highest variation was in repeatability (= intraphysician variation). The major part of the variation was, however, that from patient to patient: 33% of the total in Parameter 1 and 85% of the total in Parameter 2. CONCLUSIONS: R&R studies are applicable and are needed to evaluate and improve quality in clinical practice. This kind of analysis provides opportunities to establish which kinds of patients require particularly careful attention, which points in the process are most critical for variation, which are the most difficult aspects for each physician and call for more careful description in documents, and which physicians need further training.
Analysis of Variance↗
Evaluation of five commercial antifungal susceptibility testing systems.
Five commercial antifungal susceptibility testing systems were studied for repeatability and reproducibility as well as concordance of results with the MICs for ten reference strains belonging to six different species. Repeatability was determined by testing each strain in triplicate on the same day, and reproducibility by repeating this triple determination on three different days. On the basis of 630 yeast-antifungal agent results for Mycototal and Mycostandard, 540 for Candifast, and 450 for ATB Fungus and Diff Test, repeatability was consistently equal to or greater than 95%. Reproducibility was 80.07% for Candifast and greater than 95% for the other systems. The concordance with the reference MICs was 51.65% for Candifast, 75.33% for ATB Fungus, 80.89% for Diff Test, 90.16% for Mycostandard and 90.32% for Mycototal. Although the performance of Diff Test and ATB Fungus was satisfactory, Mycototal and Mycostandard gave notably better results with imidazoles. Mycostandard, which is easier to use and includes tests for fluconazole and itraconazole, would seem to be potentially the most useful antifungal susceptibility test available at present.
Antifungal Agents↗
Rapid method for trace determination of organochlorine pesticides and polychlorinated biphenyls in yogurt.
A new multiresidue method was developed for the analysis of 19 organochlorine pesticides and 6 polychlorinated biphenyls in yogurt. The sample was extracted twice with acetone by homogenization with an Ultra-Turrax dispersing unit, and the combined extracts were filtered. The extract was then purified by reversed-phase C18 columns and subjected to further cleanup with neutral alumina columns. The residues were determined by gas chromatography with electron capture detection. After the method was optimized, it was validated by determination of recovery percentages, precision (repeatability and reproducibility), and sensitivity (detection and quantitation limits) with yogurt samples fortified at 10 and 1 microg/kg concentration levels. The recovery of 23 organochlorine residues ranged from 77 to 95% at a level of 10 microg/kg, from 74 to 102% at a level of 1 microg/kg, and between 54 and 61% for dieldrin and alpha-endosulfan. The method is repeatable and reproducible, with relative standard deviation values <19% for all residues except dieldrin. Detection and quantitation limits were between 0.02 and 0.62 microg/kg. The analytical method proposed was quick, accurate, repeatable, and reproducible for the determination of organochlorine residues in yogurt samples.
Chromatography, Gas↗
Central and peripheral corneal thickness measured with the TOPCON specular microscope SP-2000P.
PURPOSE: Modern refractive surgery and follow up relies on a knowledge of corneal thickness (CT) and shape, and the reliability of modern instrumentation providing such data is important. This study sought to determine the performance of the TOPCON SP-2000P specular microscope in measuring CT. The aims of this study were: (a) to determine if there is any difference between the CT results obtained from the first image, the clearest of three images and the mean of measurements from three images; (b) to determine the correlation between central and peripheral CT and (c) to investigate the reliability (repeatability and reproducibility) of the SP-2000P in the determination of central and peripheral CT. METHODS: The central and peripheral CT measurements shown on the first (f), the clearest (c) of three images and the mean (m) CT shown in three images captured with the SP-2000P of 43 subjects were compared. All images were captured by the same examiner. Nineteen of the subjects (male) returned on another day and measurements were taken by two examiners. RESULTS: fCT, cCT and mCT were not significantly different from each other. The intraclass correlation coefficients (ICC) between the three values were> 0.9 for all corneal locations measured. However, the variability in the differences between fCT and cCT was relatively greater for peripheral CT (except temporal). The peripheral CT values obtained were all significantly greater than the central CT, and statistically significant correlations were found between the central and each of the peripheral thickness. There was no statistically significant between-visit or between-examiner differences in the central or peripheral CT. The ICC values for between-visit differences for central and temporal measurements were > 0.9 but for the other corneal locations, the ICC values were 0.81 to 0.88. For between-examiner differences, the ICC value was 0.82 for inferior CT and > 0.9 for the other four CT. CONCLUSIONS: Differences in CT measurements obtained from the first and clearest images captured by the SP-2000P were not statistically significant but can be clinically significant for peripheral CT. We therefore suggest the use of the CT value obtained from the clearest of three images. For every unit change in central CT, there is an approximately equivalent change in peripheral CT. Based on the ICC values, the SP-2000P showed very good repeatability and reproducibility in the determination of central CT. For the determination of peripheral CT, the repeatability and reproducibility of the SP-2000P were good and reasonably good respectively. These findings have relevance to the measurement of the cornea before and after refractive surgery.
Adult↗
Water quality monitoring in membrane filtration systems.
We report on an experimental study of UF membrane fouling by colloidal particles. Deposition colloidal particles during membrane filtration causes a decline in permeate flux. Membrane flux is monitored on a laboratory scale, crossflow employing UF membranes. The existing modified fouling index (MFI) uses a microfilter membrane as a quick test of feed water quality. The MFI is based on cake filtration, and thus, a model can be developed for flux decline predication. However, this MFI is not sensitive to the presence of smaller particles. Therefore, more recently MFI using ultrafiltration membranes (MFI-UF) was developed. This research investigates various critical aspects of the MFI-UF test for use as a water quality indicator; stability of the MFI-UF over time, linearity of the index with particulate concentration, and reproducibility (1) of the test (reusability of a UF module) and (2) module manufacture. Pressure dependence of the MFI-UF was also examined. The aforementioned criteria were examined using a polyacrylonitrile module with 13,000 molecular weight cutoff for low fouling (tap and process water). The MFI-UF was stable over time and directly related to colloidal concentration. The MFI-UF test was reproducible for one module with repeated testing; reproducible module manufacture was found for 80% of the test modules.
Journal Article↗