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PubMed1978

Effects of occlusal therapy on pantographic reproducibility of mandibular border movements.

A clinical experiment was undertaken to study the relationship between occlusal therapy and pantographic reproducibility. Twenty-six subjects were categorized according to their ability to reproduce pantographic border movements and were put into either a control nonreproducible, control reproducible, or experimental nonreproducible group. From each subject a sequence of five pantographic surveys consisting of two morning and two afternoon pantographic recordings was taken. Each survey period lasted a minimum of 30 days. The experimental subjects alone were given occlusal splint therapy and occlusal adjustment therapy during the sequence of recall periods. The relationship between the effect caused by occlusal therapy and pantographic reproducibility was analyzed. For the purpose of analysis, the pantographic recordings were assessed a numerical score using a pantographic reproducibility index. A double-blind technique was used until all data were collected.

Adult↗

PubMed1987

Allergen bronchial challenge tests: variability and reproducibility of the early response.

We evaluated allergen bronchial challenge tests (ABCTs) variability and reproducibility during 2-week intervals, respectively, in 28 and 14 Dermatophagoides pteronyssinus-sensitized patients. Increasing doses of Dpt (1.25 to 160 X 10(-3) mg) of lyophilized Dpt extract were administered at 20-minute intervals by doubling the previous dose. Dose-response curves (D-RC) were constructed for each test with the logarithm (base 2) of the allergen dose and the FEV1 in milliliters as ordinate. We analyzed different indices: the allergen doses causing a 15% decrease in FEV1 (PD15) and a 20% decrease in FEV1 (PD20), the slope of the curve beyond PD15, the overall slope, and the area under the parabolic curve. We found considerable intersubject variability in early asthmatic responses to Dpt ABCTs. Bronchoconstriction induced by allergen produced a specific D-RC for each individual. PD20 was significantly correlated with all the indices representing the whole D-RC (i.e., overall slope and area); moreover, PD20 was found on the steepest portion of the curve in 24 of 28 D-RCs. With the methodology used, we obtained a satisfactory reproducibility in a 2-week interval: the linear slope obtained by log base 2 transformation of doses was highly reproducible (p less than 0.001), as was area p under the parabolic curve. PD20 is significantly reproducible in a range of one doubling dose (twofold variation). The reproducibility of ABCTs over a short period permits solid arguments for their use in the evaluation of prophylactic treatment and in clinical research.

Adult↗

PubMed1991

Late asthmatic responses after exercise challenge are reproducible.

In this study the reproducibility of a late asthmatic reaction (LAR) after exercise challenge (EC) has been documented. Eighty-three hospitalized patients with asthma were challenged with exercise. The patients were examined according to a standardized protocol that comprised 8 minutes of bicycling at 90% of predicted heart rate. An LAR after EC was considered to have occurred when there was a fall in peak expiratory flow rate greater than or equal to 20% on three or more time points on the exercise day compared to corresponding clock time on a control day. According to these criteria, 11 patients (13.3%) experienced an LAR. Those patients were rechallenged 21 to 150 days after the first EC, without changing the therapy regimen of the patients, to study its reproducibility. Eight patients (73%) demonstrated a reproducible LAR after EC based on the criteria for a positive LAR. Although the LAR after EC was reproducible, the time points at which the LAR took place after the second EC differed from LARs after the first EC. Our results indicate that the LAR after EC occurs in a considerable number of patients with bronchial asthma and is quite reproducible.

Adrenal Cortex Hormones↗

PubMed1996

Reproducibility of lumbar paraspinal surface electromyogram power spectra.

OBJECTIVE: To establish the reproducibility of surface recordings of electromyograms from lumbar erector spinae muscles. DESIGN: Repeated measurements in 10 male volunteers under controlled conditions. METHODS: While isometric load was held constant at (2/3) and (1/3) of maximum voluntary contraction, surface electromyograms were recorded from the 4th/5th lumbar interspace on three occasions separated by at least a day. Fresh surface electrodes were applied on each test occasion. The raw electromyographic signal was filtered and digitized and the signal processed by fast Fourier transformation to give median frequency and total amplitude spectra. Linear regression lines of median frequency and amplitude against time were calculated. The 'spectral halfwidth" was defined as the full width at half maximum of the composite amplitude spectrum. Reproducibility was assessed by calculation of the intraclass correlation coefficient. RESULTS: Reproducibility of initial median frequency and spectral halfwidth were found to be excellent at both (2/3) (ICCC 0.91 and 0.88) and (1/3) (ICCC 0.84 and 0.83) maximum voluntary contraction. Initial power and regression slopes of power and median frequency were not reproducible. CONCLUSIONS: The reproducibility of two electromyographic variables, the initial median frequency and the spectral halfwidth, were found to be satisfactory.

Journal Article↗

PubMed1991

Self-reproducing systems: structure, niche relations and evolution.

A formal definition of a self-reproducing system is proposed using Petri nets. A potential self-reproducing system is a set of places in the Petri net such that the number of tokens in each place increases due to some sequence of internal transitions (a transition is called internal to the marked subset of places if at least one of its starting places and one of its terminating places belongs to that subset). An actual self-reproducing system is a system that compensates the outflow of its components by reproduction. In a suitable environment every potential self-reproducing system becomes an actual one. Each Petri net can be considered as an ecosystem with the web of ecological niches bound together with trophic and other relations. The stationary dynamics of the ecosystem is characterized by the set of filled niches. The process of evolution is described in terms of niche composition change. Perspectives of the theory of self-reproducing systems in biology are discussed.

Biological Evolution↗

PubMed1996

Reproducibility and postprocessing of gradient-echo functional MRI to improve localization of brain activity in the human visual cortex.

High reproducibility of human FMRI studies is imperative for potential clinical applications of this new method for mapping human brain functions. So far, published data are not comparable quantitatively (even at the same field strength) as differences in sequence design and parameters as well as statistical methods applied to enhance function related image contrast, in particular, to extract the size of the "activated areas," are manifold. We present a study on reproducibility of gradient-echo FMRI in the human visual cortex using the different threshold strategies for correlation analysis that shows that, (a) applying adaptive correlation thresholds results in higher reproducibility compared to a fixed (0.5) threshold; (b) highly reproducible data can be obtained on a clinical 1.5 T MRI system, at least for repeated single subject studies (i.e., standard deviation of 2-30% for signal enhancement in 72-94% of the studies and 5-50% for activated area size in 63-88% of the studies, respectively, depending on threshold strategies); however, depending also on subject cooperation; (c) reproducibility across groups (alpha = const.) is worse, i.e., standard deviations are within 33-45% for signal enhancement and 41-74% for activated area size, respectively; (d) SNR is maximum at about 30 degrees flip angle, suggesting significant contributions from T1-effects for larger flip angles. Various technical, methodological, and physiological factors are influencing variability of signal enhancement and apparently activated area size, which should be taken into account if interpreting FMRI data quantitatively.

Adult↗

PubMed1988

The reproducibility of natural head posture: a methodological study.

Current clinical interest in natural head posture (NHP) derives from studies correlating NHP to craniofacial morphology, future growth trends, and to respiratory needs. It has also been argued that NHP is the logical reference and orientation position for craniofacial analysis and the publication of illustrations. The individual or group is presented as they naturally appear in life. Hence, lateral cephalometric radiographs recorded routinely in NHP would be more meaningful for the clinician. Underpinning all these potential clinical benefits is the incompletely answered question of the clinical reproducibility of NHP. In this study a natural head posture, the orthoposition, was defined and standardized for clinical use. The effects of ear posts, an external source of eye reference (a wall mirror), sex and time were evaluated in relation to the reproducibility of recording lateral cephalometric radiographs in this natural head posture. The sample comprised 217 randomly selected 12-year-old Chinese children in Hong Kong. Boys looked up more when changing from the self-balance position to the mirror eye reference position (mean change 2 degrees, P less than or equal to 0.001). No other significant male-versus-female differences were detected. NHP reproducibility was better with a mirror (with mirror, method error = 1.9 degrees, without mirror, method error = 2.7 degrees). No significant differences in reproducibility were detected between NHP recordings taken with and without ear posts. However, without ear posts the radiographs tended to be of poor quality. The reproducibility of same-day repeat radiographs recorded with ear posts and with a mirror (after 4 to 10 minutes and 1 to 2 hours) was 1.9 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

Cephalometry↗

PubMed1999

Plasma post-heparin lipase activities in the HERITAGE Family Study: the reproducibility, gender differences, and associations with lipoprotein levels. HEalth, RIsk factors, exercise Training and GEnetics.

OBJECTIVES: Examine the reproducibility of plasma lipid and lipoprotein measurements in the HERITAGE Family Study. DESIGN AND METHODS: In a sample of 379 subjects (191 men and 188 women), reproducibility was determined for lipids, lipoproteins (done on two occasions) and post-heparin lipase assays using an Intracenter Quality Control study by generating split samples from an additional 60 subjects (35 men and 25 women), which were assayed in a blind fashion by the lipid core laboratory. Reproducibility was estimated using intraclass correlation coefficients (ICC) for the selected variables. Analytical error (ANER) and coefficient of variation (CV) were also calculated. Day-to-day variation for 10 variables including plasma cholesterol and triglycerides (TG), HDL-cholesterol and its subfractions HDL2-cholesterol and HDL3-cholesterol, LDL-cholesterol and VLDL-cholesterol, as well as apoprotein (apo) A-I, apo B, and LDL-apo B were assessed. RESULTS: In the HERITAGE study, all lipid and lipoprotein variables had ICC above 0.79. Plasma VLDL-cholesterol (31 %) and TG (23%) levels, which are well known to be highly variable from one day to another, had CVs greater than 20%. Other variables had CVs lower than 10% except for HDL2-cholesterol which reached 16%. In the intracenter reliability sub-study, the measurement errors were found to be low except for HDL2-cholesterol. For the lipases, the reproducibility of repeated samples was very high, with ICC over 0.95. The within-assay CV corresponded to 2.1 and 5.3% for hepatic lipase (HL) and lipoprotein lipase (LPL), respectively, whereas the between-assay CV reached 8-12% for HL and about 15% for LPL. Due to the complexity of these two assays, the results are considered to be quite satisfactory. CONCLUSIONS: The reproducibility of plasma lipid and lipoprotein measurements, as well as of post-heparin lipase activities, is good in the multicenter HERITAGE Family Study. In addition, the well-documented gender difference in the plasma lipoprotein profile was confirmed in the present study, women having lower fasting triglyceride and LDL-cholesterol levels than men as well as reduced cholesterol/HDL-cholesterol and increased HDL2-cholesterol/ HDL3-cholesterol ratios compared to men. Results of the present study support the notion that the higher LPL and low HL activities found in women compared to men are important factors contributing to explain gender difference in the lipoprotein profile. However, additional factors not examined in the present study are involved beyond the contribution of post-heparin lipase to the sex dimorphism in plasma lipoprotein levels.

Female↗

PubMed1999

The reproducibility of videokeratoscope measurements as applied to the human cornea.

To be useful in contact lens fitting, the videokeratoscope (VK) must be able to provide the practitioner with credible data on the vertex radius and central topography, or 'shape, of the patient's cornea. For this purpose, it is desirable that the measured value of the former should be credible at the level of 0.05 mm. In order to examine the accuracy, repeatability and reproducibility of the corneal dimensions provided by the videokeratoscope, eight eyes were measured on four different EyeSys systems at four independent sites. The order of measurement was random at each site. This amounted to a balanced uniform-level precision experiment ('ring test') of the VK instruments as defined in International Standard ISO 5725. The resulting data were analysed using the statistical procedures given in this Standard to provide a formal statement of the measurement precision of the EyeSys VK system. Based on this study, the estimated measurement precision of the EyeSys videokeratoscope as applied to the latter principal meridian of the normal human cornea is: Vertex radius: repeatability standard deviation, S(R)=0.0805, reproducibility standard deviation, S(R)=0.1041. p value: repeatability standard deviation, S(r)=0.0473, reproducibility standard deviation, S(R)=0.0574. The estimated measurement precision for the steeper principal meridian is: Vertex radius: repeatability standard deviation, S(r)=0.0771; reproducibility standard deviation, S(R)=0.1015. p value: repeatability standard deviation, S(R)=0.0698; reproducibility standard deviation, S(R)=0.0749.

Journal Article↗

PubMed2003

Reproducibility of quantitative proteomic analyses of complex biological mixtures by multidimensional protein identification technology.

If quantitative proteomic technologies are to be of widespread use to the biological community, the reproducibility of each method must be investigated and determined. We have analyzed the reproducibility of complex quantitative proteomic analyses of metabolically labeled S. cerevisiae analyzed via multidimensional protein identification technology (MudPIT). Three independent cell growths of S. cerevisiae grown in rich and minimal media and independent MudPIT analyses of each were compared and contrasted. Quantitative MudPIT was found to be intra- and interexperimentally reproducible at both the peptide and protein levels. Proteins of potential low abundance were detected, identified, and quantified by identical peptides from three independent samples. In addition, when multiple peptides were matched to a protein, the relative abundance of each peptide was in agreement across the three samples. Despite the reproducibility, errors in the experimental determination of protein expression levels occurred, but the impact of the variation was minimized by replicate experiments. Last, quantitative MudPIT analyses will likely be improved by increasing the number of peptide hits per protein in a given analysis, which will provide for greater intraexperimental reproducibility.

Amino Acid Sequence↗

PubMed2002

Reproducibility of clinical performance assessment in practice using incognito standardized patients.

BACKGROUND: The reproducibility of authentic assessment methods has been investigated for objective structured clinical examinations (OSCEs) and video assessment in general practice, but not for assessment with incognito standardized patients. PURPOSE: To investigate the reproducibility of assessment with incognito standardized patients. METHODS: A total of 27 Dutch rheumatologists in 16 hospitals were each visited by 8 incognito standardized patients presenting with different rheumatological disorders. After each visit, the standardized patient completed a case-specific checklist containing items on medical history, physical examination and management. Over a 20-month period, 254 incognito visits took place, of which 201 were first visits. The standardized patient was detected by the rheumatologist in 2 cases only. These encounters were not included in the analysis. Generalizability theory was used to investigate the reproducibility of the assessment. RESULTS: One fifth of the variance can be attributed to variation between rheumatologists. The largest variance is due to the variation in difficulty among cases. A reproducible assessment requires 3 hours of testing time (6 cases) if it is obtained through a norm-referenced interpretation of scores and 7 hours of testing time (14 cases) if it is obtained through an absolute interpretation of scores. CONCLUSION: The reproducibility of performance assessment in clinical practice by incognito standardized patients is similar to that of other authentic measurements for the assessment of clinical competence and performance.

Analysis of Variance↗

PubMed2001

Reproducibility of exercise tolerance in patients with end-stage renal disease.

OBJECTIVE: To determine the interday reproducibility of peak and submaximal exercise tolerance of patients with end-stage renal disease (ESRD). DESIGN: Repeated measures. SETTING: Day-patient rehabilitation center. PARTICIPANTS: Twelve consecutively presenting, self-selected patients with ESRD. INTERVENTIONS: All patients performed peak exercise tolerance assessments on a cycle ergometer up to the point of volitional fatigue, with a 1-week interval between the 2 tests. MAIN OUTCOME MEASURES: Cardiopulmonary, hemodynamic, and physical performance parameters were assessed at peak exercise and at the lactate threshold. Standard error of measurement, percentage coefficient of variation (CV%), intraclass correlation coefficient (ICC), and limits of agreement (LOA) were calculated to determine the reproducibility of all variables. RESULTS: CV% (range, 5%-7%) and ICCs (range, .94 - .98) for oxygen uptake and heart rate at peak exercise and lactate threshold indicated highly acceptable levels of group mean reproducibility. LOA analysis revealed satisfactory levels of reproducibility for individual patients. CONCLUSION: Taken together, these reproducibility data may be applied to clinical work, requiring the quantification of changes in the exercise tolerance of patients with ESRD after short-term interventions (eg, exercise training, therapeutic use of recombinant erythropoietin).

Exercise Tolerance↗

PubMed1987

The influence of age, relative weight, smoking, and alcohol intake on the reproducibility of a dietary questionnaire.

To evaluate factors that affect the reproducibility of a semi-quantitative food frequency questionnaire used in a large prospective study we compared an extended 99-item questionnaire with a shorter, 61-item form completed by 1497 women with an interval of nine months between. Correlation coefficients for individual items assessed by the two questionnaires were highest for beverages (Spearman r = 0.70). For other foods, coefficients ranged from 0.60 to 0.70 for items eaten frequently (or habitually), to values between 0.34 and 0.45 for foods, such as sweet potatoes and ready made pie, that were eaten less frequently. For food items, the correlation between mean frequency of consumption and the reproducibility coefficient (Spearman r) was 0.51 (p less than 0.01), formally confirming that the reproducibility of measurements was positively associated with frequency of use. Pearson correlation coefficients for calorie-adjusted intakes of nutrients between the two questionnaires ranged from 0.40 for trans-fatty acids to 0.71 for vitamin E (including supplements). These correlation coefficients did not vary materially between subjects in different categories of smoking status or tertiles of age or relative weight. Moderate alcohol use had minimal effect on correlation coefficients, but reproducibility was slightly reduced among heavier drinkers. These data indicate that this self-administered dietary questionnaire can provide reproducible information about individual food and nutrient intakes which is not altered materially by age and a number of important health habits.

Adult↗

PubMed1977

Measurement of hemagglutination-inhibiting antibody to influenza virus in the 1976 influenza vaccine program: methods and test reproducibility.

Titers of hemagglutination-inhibiting (HAI) antibody were determined for all sera obtained from participants in the 1976 Influenza Vaccine Test Program. At least eight control sera were included in each test during the vaccine trial period for the purpose of monitoring HAI test reproducibility. Estimates of day-to-day reproducibility were defined as the percentages of duplicate aliquots of the same sera, tested on two separate days, having HAI antibody titers that did not differ by more than one twofold dilution. These reproducibility estimates ranged from 89% to 97% with influenza A/New Jersey/76 and A/Mayo Clinic/74 antigens. In contrast, within-day reproducibility estimates obtained from all sets of control sera ranged from 96% to 98%. Estimates of day-to-day test reproducibility obtained with selected sera taken after vaccination that were titrated on two differen days ranged from 90% to 98%. Geometric mean titers of these sera tested weeks or months apart differed on some occasions during the test period.

Antibodies, Viral↗

PubMed1987

Reproducibility of pressor response to handgrip: influence of time intervals, strength and duration of exercise.

1. The reproducibility of pressor response to handgrip performed at different time intervals and with different combinations of the product duration x strength of the exercise was evaluated in 14 normotensive subjects recording blood pressure with a noninvasive automatic device. 2. Subjects underwent five consecutive tests (30% of maximal voluntary contraction x 90 s) at 30 min, and 24 h intervals and repeated the test after 12 months. Furthermore, they underwent at 24 h intervals a randomized sequence of handgrip tests whose product strength x duration was combined in order to achieve either a constant or an increasing level of exercise. 3. Blood pressure response to exercise performed at 30 min intervals was much less reproducible than that induced by handgrip performed at time intervals greater than or equal to 24 h. 4. Increasing gradually the product strength x duration of the handgrip test there was a proportional blood pressure increase, whereas when the product was maintained constant diastolic blood pressure increase was also constant and reproducible within each subject. 5. This study shows that it is possible to obtain reproducible diastolic blood pressure responses to handgrip test measuring blood pressure with a non-invasive automatic device when the tests are performed at a time interval of at least 24 h. The choice of the strength and of the duration of the exercise is very important for the reproducibility of the test.

Adult↗

PubMed1988

Inter-examiner reproducibility of probing pocket depths in molar furcation sites.

This investigation was designed to determine the reproducibility of probing pocket depths in maxillary facial and mandibular facial and lingual grade II and III molar furcation sites. 80 untreated molar teeth with 102 furcation invasions due to periodontitis were probed with a pressure-sensitive periodontal probe by 3 examiners. 8 sites per furcation were measured by each examiner at a single examination. The sequence of examiner probing was rotated in order to evaluate the effect of sequential probing. Tracings were made from radiographs of the inter-root separations in order to classify the interradicular space and to determine the effect of root separation on reproducibility. Data was analyzed by regression analysis. Pearson correlations, intraclass correlations, and the Student-Newman-Keuls test. Analysis indicated a high reproducibility of the maxillary facial and mandibular facial and lingual furcation sites in this untreated adult sample. No effect was due to probing sequence. The mid-root prominences, the line angles, and the internal surface sites of the furcation roots were recordable and reproducible, while the horizontal measurements were not consistently recordable. The reproducibility of the facial and lingual furcation sites that were probed decreased with an increase in probing pocket depth and an increased degree of root separation.

Clinical Competence↗

PubMed1981

Alternative ways of estimating serological titer reproducibility.

A quantitative measure of the reproducibility of serum antibody titers has recently been proposed (R. J. Wood and T. M. Durham, J. Clin. Microbiol. 11: 541-545, 1980). The measure advocated is "the probability that the maximum ratio of two distinct (integer) titers (obtained in the blind) on the same specimen will not exceed 2." This measure of the reproducibility of serological titers is considered to be a fixed probability for any given specimen and set of test conditions. Although it is a fixed constant during the time period of a study, there are alternative methods one might use to compute an estimate of it, using laboratory data. Four such methods of estimating test reproducibility are discussed and evaluated. The estimates obtained from the two principle methods are evaluated quantitatively by means of Monte Carlo computer simulation. The simulation results show that, from a given sample of replicate integer titers, these two principal methods yield estimates that are highly correlated. In addition, with moderate numbers of replicates (sample size) these methods provide estimates that are on the average properly directed at the true reproducibility values (that is, are essentially, unbiased), particularly when the true reproducibility of the test is at least 0.9. The reliability, or stability, of the alternative estimates is studied for selected sample size.

Analysis of Variance↗

PubMed1975

Reproducibility of the analytab (API 20E) system.

The reproducibility of the Analytab (API 20E) system for identification of Enterobacteriaceae was evaluated with 110 clinical isolates. Each isolate was identified by two technologists at different times. Genus-species identification was 97.3% reproducible; however, only 55.5% of the strains gave identical reactions in all 20 of the API 20E biochemical tests on repeat testing. Of those strains which varied, 56% possessed only one variable biochemical test. The reproducibility for each biochemical test was calculated and ranged from 89 to 100%. A subset of 20 of the most variable strains was tested further under conditions of varying incubation time (15 and 22 h) and inoculum concentration (10(7), 10(5), and 10(3) colony-forming units per ml), and by having four technologists interpret the test results. The reproducibility for each biochemical test for these 20 variable strains ranged from 86 to 99%. Less variation in interpretation by technologists was seen at an incubation time of 22 h and an inoculum concentration of 10(7) colony-forming units per ml. Consideration of the reproducibility for each biochemical test can aid in determining the probability that two isolates suspected of being the same strain, but with API profiles which differ by one or more biochemical test results, are in fact the same strain. Variables such as inoculum size, incubation time, technologist interpretation, and strip variability affect the API test results and should be standardized to minimize their effects.

Bacteriological Techniques↗