PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Reproducibility”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,531 records · Page 85Linked to original sources
PubMed1987

Reproducibility of platelet survival time measurements in patients with peripheral arterial occlusive disease.

In this study we investigated the reproducibility of 111-In-platelet survival time (PST) measurements and of plasma levels of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF 4) in 30 patients (median age: 60.5 years) with arteriographically proven peripheral arterial occlusive disease (PAOD) in a chronic stable phase. PST calculated by both the weighted mean - WM - (1. investigation: 187.1 [median] hours - repeat investigation: 188.3 hours) and multiple hit - MH - model (181.4----177.4 hours) demonstrated only a small spontaneous variation. The median coefficient of variation (CV) was 3.0 (WM) and 3.2 (MH), respectively. The reproducibility of beta-TG (CV: 6.1) was also satisfactory. We conclude that the good reproducibility of PST and plasma levels of beta-TG make them well suited to judge the influence of platelet-suppressant drugs on these parameters in patients with PAOD.

Adult↗
PubMed1991

Stability and reproducibility of time structure in spontaneous behavior of male rats.

The computer pattern recognition system for the study of spontaneous rat behavior has allowed new analytical techniques which expand the definition of experimentally induced changes in behavior. As with any technique, the stability of the measures must be considered when evaluating overall sensitivity. This study evaluates the stability and reproducibility of three behavioral measures: a measure of the number of initiations of specific behavioral acts, a measure of the total time of each act, and a measure of behavioral time structure. Normal statistical parameters are used to evaluate the significance of changes detected using the first two measures, but the third measure utilizes K-functions, the bootstrap and ad hoc criteria to evaluate significance of observed changes. This study compares the stability of results from these three measures as applied to fourteen different groups of control Sprague-Dawley male rats. All three measures provided stable and reproducible results, but the measure of time structure, the K-function analysis, provided the greatest consistency. Behavior, particularly spontaneous behavior, has traditionally been perceived as being intrinsically variable. However, this study shows that the computer pattern recognition system and its analytical techniques provide stable and reproducible values that vary only a few percent.

Amphetamine↗
PubMed1976

Cytotoxic testing for food allergy: evaluation of reproducibility and correlation.

Cytotoxic food tests still present conflicting opinions concerning their validity. Nine atopic patients with or without a history of food allergy were studied along with 5 nonatopic patients. All tests were conducted in a double-blind fashion with 6 determinations for each of 10 food antigens. Reproducibility of the test (5/6 positive or negative) was demonstrated with wheat, milk, yeast, chocolate, and orange. In the nonatopic group, reproducible results were obtained for wheat, egg, yeast, chocolate, and chicken. Clinical correlation with 11 foods in 7 patients was demonstrated. However, there were 46 positive tests without correlation and 2 negative tests with positive histories. Therefore, there appears to be reproducibility of the tests to only 3 foods but no apparent correlation with clinical symptoms. At the present time, cytotoxic tests offer no reliable help in establishing the diagnosis of food allergy.

Animals↗
PubMed1986

The reproducibility of acute lymphoblastic leukemia phenotype determinations: evaluation of monoclonal antibody and conventional hematopoietic markers.

Peripheral blood and/or bone marrow lymphoblasts from 25 patients with acute lymphoblastic leukemia (ALL) were tested with a panel of monoclonal antibodies (MoAbs) and conventional hematopoietic markers by three different laboratories. The results were analysed to evaluate the reproducibility of ALL phenotype determinations. Specimens were transported between laboratories by 24-h courier service and were classified on the basis of indirect immunofluorescence MoAb reactivities as follows: B-lineage ALL (BA-1+T-MCS-2-); T-lineage ALL (T+BA-1-MCS-2-); myeloid antigen ALL (MCS-2+BA-1-CALLA-T-) and unclassified ALL (BA-1-MCS-2-CALLA-T-). Conventional marker studies for surface immunoglobulin (sIg), cytoplasmic immunoglobulin (cIg), sheep erythrocyte rosette formation (E) and nuclear terminal deoxynucleotidyl transferase (TdT) were also performed. In the cases with sufficient marker data to permit classification, 90% (18/20) were identically classified by different laboratories and this concordance was statistically significant (p less than 0.05). The agreement between laboratories for individual MoAb and conventional marker analyses was statistically significant (p less than 0.05) for all markers with the exception of BA-2, cIg and TdT determinations. Six of 7 discordant BA-2 cases represented BA-2+ evaluations which had subsequent BA-2- results following specimen transportation. These findings suggest instability of the BA-2 antigen to transport conditions. A similar pattern of positive to negative evaluations following transportation was observed in 5/5 discordant results involving other MoAbs. Disagreement between laboratories for cIg and TdT determinations implies that the detection of cytoplasmic or nuclear antigens may be more prone to subjective interpretation than cell surface antigen marker analyses. Our findings suggest that immunofluorescence marker studies employing MoAbs to cell surface antigens are in general highly reproducible. Our results also indicate that specimen storage conditions and the cellular location of target antigens are important variables which may affect the reproducibility of ALL phenotype determinations.

Antibodies, Monoclonal↗
PubMed1984

Reproducibility of multistage graded exercise testing in patients with chronic stable angina.

Exercise testing is widely used for the diagnosis of ischaemic heart disease and for the evaluation of antianginal drugs. To assess reproducibility, analysis was carried out on 128 paired graded exercise tests from 103 patients performed at the same time of day and under identical conditions. Six different parameters were evaluated and compared between the basal test (no treatment) and the placebo test. During the basal period the mean (+/- SEM) exercise time to the development of angina was 6.0 (+/- 0.2) min and the 1 mm ST depression time was 4.1 (+/- 0.2) min. After 2 weeks of placebo the exercise time was 6.1 (+/- 0.2) min (P = NS) and the 1 mm ST depression time was 4.2 (+/- 0.2) min (P = NS). There was no significant difference between the resting or maximum heart rate on either test and the maximum ST segment depression (leads CM5 and CC5) was unaltered. In a second group of 17 patients where the basal tests were performed in the afternoon and the placebo tests in the morning, heart rate and ST segment were found to be reproducible but there was a significant difference in exercise time: 5.7 (+/- 0.7) min for the basal test and 8.3 (+/- 0.5) min for the placebo test (P less than 0.001); and of the 1 mm ST depression time: 2.7 (+/- 0.4) min for the basal test, and 5.4 (+/- 0.5) min for the placebo test (P less than 0.001). We conclude that exercise tests done under standardised conditions in the morning are highly reproducible in patients with chronic stable angina and therefore provide a valuable test for the evaluation of antianginal drugs.

Aged↗
PubMed1987

Occurrence and reproducibility of the "skip" phenomenon in bactericidal testing of Staphylococcus aureus.

A "skip" phenomenon, in which subcultures to determine bactericidal endpoints show discordant results, can make bactericidal testing of Staphylococcus aureus difficult to interpret. Either a single or several consecutive concentrations may be skipped, with insignificant growth from these concentrations, but heavy growth from higher antimicrobic concentrations. Replicate macrodilution minimum bactericidal concentration testing of cephalothin against S. aureus was investigated to determine the frequency and reproducibility of the skip phenomenon in this test. In preliminary testing, the skip phenomenon occurred at 24 hr in 11 of the 30 tests performed on ten S. aureus strains. Incubation of tubes for 48 hr before subculture markedly reduced the number of tests containing a skip tube (four of 30). The skip phenomenon was not reproducible either within concurrent replicate testing or on repeat testing of the same isolate on subsequent days. The ten strains were retested in replicative trials using the macrodilution test comparing Mueller-Hinton broth (MHB) and MHB supplemented with Tween 80. The number of skips occurring in the supplemented broth test was the same (two of 22) at 24 hr as nonsupplemented broth. For reproducible results, macrodilution minimum bactericidal testing requires performance of the test in duplicate, with repeat subculture at 48 hr if the skip phenomenon occurs in both trials at the 24-hr subculture. Killing curves performed on these isolates did not appear to demonstrate any relationship between the skip phenomenon and the paradoxical effect described by Eagle.

Cephalothin↗
PubMed1989

Reproducibility of left ventricular mass measurements by two-dimensional and M-mode echocardiography.

Both two-dimensional and M-mode echocardiography provide accurate estimates of left ventricular mass. However, their reproducibility in serial studies has not been compared, although this issue is critical to evaluation of regression of hypertrophy. To determine which technique provides more reproducible estimates of left ventricular mass, three serial studies were performed prospectively in each of eight normal adults over 5 months. Both two-dimensional and M-mode echocardiograms were obtained at each of these 24 studies. Measurements were performed by two independent observers who did not know patient identity. For the two-dimensional method, left ventricular mass was determined with use of a computer light-pen system and the truncated ellipsoid formula. For the M-mode method, mass was calculated from Penn convention measurements with use of the cube formula. At study 1 the group mean left ventricular mass by two-dimensional echocardiography (115 +/- 20 g) did not differ from that by M-mode study (127 +/- 37 g, p = NS). However, serial estimates of left ventricular mass were more reproducible by two-dimensional echocardiography. The mean difference among the three serial two-dimensional studies in each individual was 4.8 +/- 4 g (4.2 +/- 3%) by the two-dimensional method, but was 18.5 +/- 13 g (14.9 +/- 10%) by the M-mode method (p = 0.01). Interobserver results for left ventricular mass by two-dimensional echocardiography correlated closely (r = 0.95, n = 24, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Reproducibility of rotational panoramic radiography: mandibular linear dimensions and angles.

The reproducibility of nine mandibular variables (linear dimensions and angles) assessed from panoramic radiographs with the Orthopantomograph 5 (Siemens) was investigated. Attention was given to the possible influence of recording the reference number of the head positioner with one or two radiographers. Two separate exposures of three groups of patients were made under different radiographic conditions, each group representing one method. Acceptable reproducibility was observed for the vertical and angular variables, the method variance being mostly within 3% of the total variance. Horizontal variables were clearly more unreliable. No statistically significant differences were observed between the reproducibility of the right and left sides. A negative correlation was found between the angular variables within two groups. For most variables, only small differences among the methods were found. The highest reliability was obtained when the same radiographer recorded the reference number of the head positioner and made both exposures. An accuracy study on five dried skulls showed an image magnification of approximately 18% to 21% for the vertical variables, whereas the gonial angle assessed from a panoramic film was almost identical to that measured on the dried mandible.

Cephalometry↗
PubMed2005

Estimation of ACL forces by reproducing knee kinematics between sets of knees: A novel non-invasive methodology.

In situ force in the anterior cruciate ligament (ACL) has been quantified both in vitro in response to relatively simple loads by means of robotic technology, as well as in vivo in response to more complex loads by means of force transducers and computational models. However, a methodology has been suggested to indirectly estimate the in situ forces in the ACL in a non-invasive, non-contact manner by reproducing six-degree of freedom (six-DOF) in vivo kinematics on cadaveric knees using a robotic/UFS testing system. Therefore, the objective of this study was to determine the feasibility of this approach. Kinematics from eight porcine knees (source knees) were collected at 30 degrees , 60 degrees , and 90 degrees of flexion in response to: (1) an anterior load of 100 N and (2) a valgus load of 5 N m. The average of each kinematic data set was reproduced on a separate set of eight knees (target knees). The in situ forces in the ACL were determined for both sets of knees and compared. Significant differences (rho<0.05) were found between the source knees and the target knees for all flexion angles in response to an anterior load. However, in response to valgus loads, there was no significant difference between the source knees and the target knees at 30 degrees and 90 degrees of flexion. It was noted that there was a correlation between anterior knee laxity (the distance along the displacement axis from the origin to the beginning of the linear region of the load-displacement curve) and internal-external rotation. These data suggest that in order to obtain reproducible results one needs to first match knees to knees with comparable anterior knee laxity. Thus, an estimate of the in situ forces in the ACL during in vivo activities might be obtainable using this novel methodology.

Animals↗
PubMed2006

Development of a novel articulator that reproduced jaw movement with six-degree-of-freedom.

A novel robotic articulator that reproduced a six-degree-of-freedom jaw movement was developed and tested. A precise six-axis micro-positioning stage was employed for this articulator. A high-resolution jaw-tracking device measured the functional jaw movement of the patient and a six-axis micro-positioning stage reproduced recorded jaw movement data. A full veneer crown restoration was fabricated with this articulator system. A working cast was mounted on the positioning stage of the articulator. An occlusal table with soft wax was attached on the cast tooth die, and the jaw movements were reproduced to create a functionally generated path on the occlusal table. The finished occlusal record was used to obtain the wax pattern for the crown. In this subject, no intra-oral occlusal adjustment was necessary for setting the finished full veneer crown. Since this articulator could perform a precise reproduction of the dynamic jaw motion during the functional jaw movement, this system has potential to improve accuracy of the prosthetic teeth occlusion.

Biomimetics↗
PubMed2005

Bile duct ligation plus hyperammonemia in rats reproduces the alterations in the modulation of soluble guanylate cyclase by nitric oxide in brain of cirrhotic patients.

Modulation of soluble guanylate cyclase (sGC) by nitric oxide (NO) is altered in brain from cirrhotic patients. The aim of this work was to assess whether an animal model of cirrhosis, bile duct ligation, alone or combined with diet-induced hyperammonemia for 7-10 days reproduces the alterations in NO modulation of sGC found in brains from cirrhotic patients. sGC activity was measured under basal conditions and in the presence of NO in cerebellum and cerebral cortex of the following groups of rats: controls, bile duct ligation without or with hyperammonemia and hyperammonemia without bile duct ligation. In cerebellum activation of sGC by NO was significantly lower in bile duct ligated rats with (12 +/- five-fold) or without (14 +/- six-fold) hyperammonemia than in control rats (23 +/- seven-fold). In cerebral cortex activation of sGC by NO was higher in rats with bile duct ligation with hyperammonemia (124 +/- 30-fold) but not without hyperammonemia (59 +/- 15-fold) than in control rats (66 +/- 11-fold). The combination of bile duct ligation and hyperammonemia reproduces the alterations in the modulation of soluble guanylate cyclase by NO found in cerebral cortex and cerebellum of cirrhotic patients while bile duct ligation or hyperammonemia alone reproduces the effects in cerebellum but not in cerebral cortex.

Animals↗
PubMed2004

Reproducibility and responsiveness of the Whiplash Disability Questionnaire.

This study continued the validation of a Whiplash Specific Disability Questionnaire (WDQ) that was developed from the Neck Disability Index (NDI) using self-reported disabilities in a group of participants experiencing whiplash-associated disorders [J Manipulative Physiol Ther 14 (1991) 409]. Previous research has established the content, construct and face validity and internal consistency of the WDQ. The aim of this study was to establish the short-term and medium-term test-retest reliability and responsiveness of the WDQ. Participants (n = 63) receiving physiotherapy treatment for WAD were recruited from 30 private physiotherapy practices in Melbourne, Australia. Each participant completed three WDQ questionnaires over a 1-month period, the first two separated by 24 h. The third questionnaire contained an additional item that asked respondents to rate their perceived change in condition over the month. Reproducibility was determined using an intra-class correlation co-efficient. Responsiveness was assessed via correlation with participant perceived change, the effect size, standardised response mean (SRM) and the responsiveness statistic. Results demonstrated excellent short-term test-retest reliability (ICC 0.96). Reproducibility over 1 month was excellent (ICC 0.93). Correlation between change in WDQ score over 1 month and participant perceived change was r(s) = 0.64, the effect size was 0.03, the SRM was 0.08 and the responsiveness statistics were 0.90 (participants who improved) and -1.60 (participants who deteriorated). The minimal detectable change of the WDQ was established at 15 points. These results demonstrate that the WDQ has excellent short- and medium-term reproducibility and responsiveness in a population seeking treatment for WAD.

Adolescent↗
PubMed1986

Reproducibility of ventricular tachycardia suppression by antiarrhythmic drug therapy during serial electrophysiologic testing in coronary artery disease.

The short-term reproducibility of pharmacologic suppression of ventricular tachycardia (VT) induced by programmed cardiac stimulation was tested in patients with coronary artery disease presenting with documented recurrent VT or ventricular fibrillation. Sixty-three consecutive patients in whom sustained VT (30 patients) or nonsustained VT (33 patients) was induced by programmed cardiac stimulation without antiarrhythmic drug treatment, and in whom at least 1 oral antiarrhythmic drug regimen suppressed the induced VT during serial electrophysiologic testing, were entered into the study. Programmed cardiac stimulation was repeated after a mean of 37 +/- 14 hours during the same antiarrhythmic drug regimen. No VT was induced in 59 of the 63 patients during the second study, resulting in a rate of 94% for short-term reproducibility of pharmacologic suppression of induced VT. Of the remaining 4 patients, programmed cardiac stimulation during the second drug study induced sustained VT in 1 patient and nonsustained VT in 3 patients. There was no significant difference in mean right ventricular effective refractory period and QT interval between the first and second drug study. Thus, in this selected population of patients, pharmacologic suppression of electrically induced VT is a reproducible phenomenon.

Aged↗
PubMedDate not supplied

Reproducible demonstration of blood flow at duodenal ulcer margins by endoscopic reflectance spectrophotometry.

Changes in gastrointestinal mucosal blood flow were evaluated by index of oxygen saturation (ISO2) and index of hemoglobin concentration (IHB) measured with a reflectance spectrophotometer. This report examined the reproducibility of endoscopic measurements of ISO2 and IHB. Study 1: The everted stomachs of three anesthetized rats provided hands-on instruction (one teacher and three learners). Six sets of readings were obtained endoscopically (the mean calculated to give the measurement) at each level of gastric mucosal perfusion when gastric blood flow was varied by withdrawing blood from the carotid artery. Study 2: Fourteen duodenal ulcer patients with ulcer bleeding were transfused and stabilized. Two endoscopists (one teacher and one learner) took turns to obtain endoscopic ISO2 and IHB measurements at the margin of the ulcer and at the adjacent normal appearing mucosa. delta ISO2 was calculated as the ulcer margin value minus adjacent mucosa value. In study 1, the correlation coefficients between the ISO2 measurements of the experienced and those of the other three observers were 0.99, 0.97, and 0.97, respectively. In study 2, the correlation coefficients between the ISO2 measurements obtained at the ulcer margin and at the adjacent normal mucosa, and delta ISO2 obtained by the experienced observer and one of the three learners were 0.94, 0.97, and 0.94, respectively. Relative to the adjacent area, 79% of the duodenal ulcers studied had increased (+delta ISO2), and 21% had decreased blood flow (-delta ISO2) at the ulcer margins. IHB measurements were less reproducible, particularly at the ulcer margin. The measurements of ISO2 and delta ISO2 were reproducible in the everted rat stomach and in duodenal ulcer patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1999

Cytokine and immunoglobulin concentrations in cervical secretions: reproducibility of the Weck-cel collection instrument and correlates of immune measures.

Elucidation of local immune response at the cervix is important for understanding and evaluating STD vaccine approaches currently being proposed. However, no well-validated method exists for the collection of cervical secretions for evaluation of cervical immune response. The purpose of this study was to determine the reproducibility of the Weck-cel sponge used to collect cervical secretions for immunological assessment. Additionally, it was possible to examine correlates of immunity as part of our investigation. Two cervical secretion specimens were collected sequentially from each of 120 women using Weck-cel sponges. Cervical secretions were collected prior to Pap smear sampling to avoid blood contamination. At the laboratory, the duplicate specimens were weighed and tested in replicate wells to determine the concentration of two cytokines (IL-10 and IL-12) and two immunoglobulin isotypes (IgG and IgA). IL-12, total IgG, and total IgA showed a strong correlation between samples from the same woman ranging from 0.78 to 0.84. Kappa coefficients obtained after categorizing assay results ranged from 0.62 to 0.67. Variance components analysis suggested that 69% to 85% of the variance observed was accounted for by between-women variance, with the remaining variability attributed to variation between samples collected from the same woman. IL-10 results were less reproducible than those obtained from the other assays examined, suggesting problems with the assay used to measure this cytokine rather than with the Weck-cel sampling instrument. Various factors were found to significantly correlate with cytokine and immunoglobulin measures at the cervix. Age and reproductive status were associated with all four immune measures; women over 50 years of age and those who were postmenopausal had increased concentrations of IL-10, IL-12, IgG, and IgA. Hemoglobin concentrations were positively correlated with IgG and IL-10 concentrations, but not with IgA or IL-12 concentrations, suggesting local production of IgA and IL-12. The concentration of all immune measures decreased with increasing volume of collection. No significant association was observed between time from collection to freezing of specimens and concentrations of cytokines or immunoglobulins. Overall, our data suggest that measurement of immunological parameters in cervical secretions collected using Weck-cel sponges are reproducible. In addition, various correlates of cytokine and immunoglobulin concentrations were identified.

Adult↗
PubMed1984

Female urethral pressure profile; reproducibility, axial variation and effects of low dose oral contraceptives.

The variability of the female urethral pressure profile as determined with the microtransducer technique was studied in a group of healthy nulliparous women according to a standardized methodology. Estimation of the short term reproducibility, as well as investigation of which of several serially recorded urethral pressure profiles can be considered as most representative of the basal condition, was carried out by performing serial urethral pressure profile recordings within the same study session in 12 women. Estimation of the long term reproducibility and investigation of the influence of axial rotation of the transducer membrane on the measurements were carried out in 20 women who were on low dose oral contraceptives. No influence of low dose oral contraceptives on the urethral pressure profile measurements could be detected. When serial recordings were made within the same study session, the lowest values for the urethral closure pressure were generally observed in the 3rd and 4th recordings. The short term and long term reproducibility of urethral pressure profile measurements were generally the same for the measurements in both the supine and the sitting positions. Rotation of the transducer membrane as well as positional changes significantly influenced the urethral pressure profile recordings. The recordings in which the transducer was oriented ventrally generally showed a shorter urethral length and a higher closure pressure than those in which the pressure transducer was oriented laterally or dorsally. These observations as well as the observations made during dynamic testing indicate an asymmetrical distribution of urethral closure forces in healthy nulliparous women.

Adult↗
PubMed2000

Duplicate sampling reproducibility of atmospheric residues of herbicides for paired pan and high-volume air samplers.

The reproducibility of collection of atmospheric residues of the herbicides 2,4-D and triallate as bulk (wet plus dry) deposition samples by paired pan samplers and as particulate (filter) and vapour (PUF/XAD-2 resin cartridge) samples by paired high-volume air samplers was determined. Variability of herbicide concentrations in paired bulk deposition samples was within 25% for 65 and 80% of the samples for 2,4-D and triallate, respectively, with approximately 90% of the paired samples being within a factor of 2 for both herbicides. The vapour samples of 2,4-D and triallate showed similar reproducibilities. The highest reproducibility was observed for the filter samples with 92% of the paired data sets for 2,4-D being within 25% variability. No triallate was detected in the filter samples.

2,4-Dichlorophenoxyacetic Acid↗