Significant Difference In Reproducibility Research Articles

ПРИМЕНЕНИЕ СОРБЕНТА ДЛЯ ТВЕРДОФАЗНОЙ ЭКСТРАКЦИИ НА ОСНОВЕ ГИПРОМЕЛЛОЗЫ ДЛЯ КОЛИЧЕСТВЕННОГО ОПРЕДЕЛЕНИЯ КИСЛОТЫ САЛИЦИЛОВОЙ В КОМБИНИРОВАННЫХ ЛЕКАРСТВЕННЫХ ПРЕПАРАТАХ

Introduction. In quality control of pharmaceutical formulations, there are methodological approaches based on the preliminary separation of sample components and approaches without preliminary separation. The use of solid-phase extraction (SPE) allows to separate analytes during sample preparation, with the separation selectivity determining the analysis selectivity as a whole. Currently, sorbents that provide selectivity in interaction with the analyte are of interest. Various derivatives of cellulose are used to obtain selective sorbents: ethylcellulose, hydroxypropylmethylcellulose (hypromellose), carboxymethylcellulose, etc. On the pharmaceutical market of the Russian Federation, there are pharmaceutical formulations with the active pharmaceutical substance salicylic acid. The use of selective SPE for analysis is a promising direction of research in drug quality control. Aim. Evaluation of the metrological characteristics of benzocaine quantitation by UV-spectrophotometry in certain pharmaceutical formulations using hypromellose sorbent for solid-phase extraction. Material and methods. The sorbent using a method developed by us was obtained. Salicylic acid (FS.2.1.0634, Russia State Pharmacopoeia XV ed.) to form active binding sites in sorbent structure was applied. The sorbent structure is polycyanoacrylate matrix with hypromellose fragments, the surface area is 255.50 m2/g, pore volume is 0.1433 cm3, pore diameter is 5.32 nm. The sorption capacity of hypromellose sorbent for benzocaine was 12.2 ± 0.8 μg/g. The SPE technique is proposed. SPE includes the stages: conditioning, sample addition and step-by-step elution with purified water and sodium hydroxide solution 0.1 mol/L. The spectrophotometer SF-56 was used to measure the absorbance at an analytical wavelength of 286 nm. To evaluate the selectivity (specificity) of sample preparation during chromatographic (SPE) separation of pharmaceutical formulations, absorption spectra of eluates in the wavelength range of 200-400 nm were scanned. The salicylic acid identification in the eluate was carried out based on absorption peaks at 228 and 298 nm.The salicylic acid calibration curve in the range of 1-20 μg/ml. To determination the metrological characteristics of salicylic acid quantitation method, 16 parallel determinations of samples of each pharmaceutical formulation were made. Statistical processing of the experimental results and determination of the metrological characteristics evaluation of analytical technique were carried out in accordance with general pharmacopoeial monograph (OFS.1.1.0013 "Statistical processing of results of physical, physicochemical, and chemical tests"). Results. When realizing the salicylic acid quantitation technique for measuring absorbance, it is advisable to use only the first portions of eluate (a solution of sodium hydroxide) in a volume of 5-10 ml were obtained. The relative error in determining the average content of salicylic acid in the analyzed preparations ranged from 1.18 to 1.44% for methods with solid-phase extraction (SPE) and 1.86-2.62% in its absence. It has been shown that there is a statistically significant difference in reproducibility for all preparations, as indicated by F-criteria values ranging from 7.81 to 13.5, exceeding their tabulated values. For the method without solid-phase extraction (SPE), there was an overestimation of the salicylic acid content in all cases, increasing the systematic error on average by 87.5%. Conclusion. The possibility of using a selective hypromellose sorbent for sample preparation for salicylic acid quantitation determination in pharmaceutical formulations has been showed. The use of sorbent for analysis provides to systematic error decrement of salicylic acid quantitation by an average of 87.5%.

APPLICATION OF SELECTIVE HYPROMELLOSE SORBENT FOR THE BENZOCAINE QUANTITATION IN PHARMACEUTICAL FORMULATIONS

Introduction. In quality control of pharmaceutical formulations, there are methodological approaches based on the preliminary separation of sample components and approaches without preliminary separation. The use of solid-phase extraction (SPE) allows to separate analytes during sample prepa-ration, with the separation selectivity determining the analysis selectivity as a whole. Currently, sorbents that provide selectivity in interaction with the analyte are of interest. Aim. Evaluation of the metrological characteristics of benzocaine quantitation by UV-spectrophotometry in certain pharmaceutical formulations using hypromellose sorbent for solid-phase extraction. Material and methods. The sorbent using a method developed by us was obtained. Benzocaine (FS.2.1.0634, Russia State Pharmacopoeia XV ed.) to form active binding sites in sorbent structure was applied. The sorbent structure is polycyanoacrylate matrix with hypromellose fragments, the sur-face area is 255.50 m2/g, pore volume is 0.1433 cm3, pore diameter is 5.32 nm. The sorption capacity of hypromellose sorbent for benzocaine was 12.2±0.8 μg/g. The SPE technique is proposed. SPE includes the stages: conditioning, sample addition and step-by-step elution with purified water and hydrochloric acid solution 0.1 mol/L. The spectrophotometer SF-56 was used to measure the absorbance at an analytical wavelength of 286 nm. To evaluate the selectivity (specificity) of sample preparation during chromatographic (SPE) separation of pharmaceutical formulations, absorption spectra of eluates in the wavelength range of 200400 nm were scanned. The benzocaine identification in the eluate was carried out based on absorption peaks at 220 and 286 nm. The benzocaine calibration curve in the range of 120 μg/ml. To determination the metrological characteristics of benzocaine quan-titation method, 11 parallel determinations of samples of each pharmaceutical formulation were made. Results. When realizing the benzocaine quantitation technique for measuring absorbance, it is advisable to use only the first portions of eluate (a solu-tion of hydrochloric acid) in a volume of 510 ml were obtained. The relative error of benzocaine average concentration in the pharmaceutical formula-tions ranged from 1.28 to 1.34% for technique that included the SPE stage, and from 1.86 to 2.02% for technique that did not include it. A comparison of the modifications of the spectrophotometric quantitation of benzocaine in pharmaceutical formulation using hypromellose sorbent and technique without the SPE did not reveal a statistically significant difference in reproducibility. For the modification technique without SPE, an increase of benzo-caine concentration and in determination relative error by an average of 48.0% were observed. Conclusion. The possibility of using a selective hypromellose sorbent for sample preparation for benzocaine quantitation determination in pharmaceu-tical formulations has been showed. The use of a sorbent for SPE at the sample preparation stage reduces the systematic error of benzocaine spectro-photometry quantitation for the analyzed pharmaceutical formulations by an average of 79.2%.

Speckle tracking stress echocardiography in children: interobserver and intraobserver reproducibility and the impact of echocardiographic image quality

Speckle tracking echocardiography (STE) is increasingly used during functional assessments. However, reproducibility and dependence on echocardiographic image quality for speckle tracking stress echocardiography in pediatric patients have not been studied to date. 127 consecutive normotensive children without structural heart disease (mean age 13.4 ± 3.0 years, 50.4% female) underwent a stepwise semisupine cycle ergometric protocol. Left ventricular (LV) myocardial peak strain and strain rate were assessed at rest and during exercise. Interobserver and intraobserver assessments were performed and analyzed regarding echocardiographic image quality. LV peak global strain and strain rate were well reproducible with narrow limits of agreement without any significant bias both at rest and during all stages of exercise testing. Moreover, strain rate reproducibility slightly deteriorated in values between −1.5 and −3 s−1. Surprisingly, there was no significant difference in reproducibility between optimal, intermediate and poor quality of echocardiographic images. STE derived strain and strain rate measurements in children are feasible and highly reproducible during semisupine cycle ergometric stress echocardiography. Echocardiographic image quality does not seem to influence strain (rate) reproducibility. Myocardial deformation measurements in images with suboptimal visualization quality must be interpreted with caution.

Optimising the imaging plane for right ventricular magnetic resonance volume analysis in adult patients referred for assessment of right ventricular structure and function.

Our aim was to evaluate the reproducibility and accuracy of using short-axis and axial (transaxial) plane for magnetic resonance imaging analysis in adult patients referred for assessment of right ventricular (RV) structure and function. Twenty consecutive subjects (10 male, 10 female, mean age 32.2 ± 14.8 years) who were referred for RV assessment and had cardiac magnetic resonance imaging were retrospectively selected. Axial and short-axis manual contouring was performed using cine steady-state free precession sequences by three experienced imaging specialists. The reproducibility of end diastolic volumes, end systolic volumes and ejection fraction was assessed with intraclass correlation coefficients (ICCs) and paired t-tests. Left ventricular stroke volume (LVSV) and RV stroke volumes (RVSV) were compared with concordance correlation coefficients (CCCs) and t-tests to determine accuracy. The concordance between the RVSV and LVSV was good using both methods (axial RVSV CCC = 0.93, short-axis RVSV CCC = 0.86). Paired t-test and analysis of variance showed that the LV/RV stroke volume differences were not significant (p = 0.17). There was slight improvement in interobserver reliability with end systolic volume measurements (axial ICC = 0.92, short-axis ICC = 0.81) but this failed to reach statistical significance (p = 0.37). There was excellent intraobserver variability (ICC > 0.9). This study shows that there is no statistically significant difference in reproducibility or accuracy using the short-axis or axial orientations in RV volume analysis in adult patients being referred for RV assessment.

模擬大腸ファントムを用いたCTコロノグラフィの画像評価～再構成スライス厚が及ぼす影響について～

Computed tomography colonography (CTC) is a robust and reliable imaging test of the colon. Recent studies show good sensitivity for the identification of nonpolypoid (flat) lesions as well. The purpose of this study was to determine the accuracy and reproducibility of a volume-rendering (VR) and virtual gross pathology (VGP) technique for detecting a polypoid lesion phantom by varying slice thickness. The scan of a simulated house-made phantom was performed using a 16-slice CT scanner with varying combinations of tube voltage (120 kVp), effective exposure (100 mAs), detector configuration (16×0.75 mm), rotation time (0.75 s), helical pitch (0.688, 0.938, 1.066 and 1.188), reconstruction kernel (A, B and C), and section thickness/reconstruction interval (0.8/0.4, 1.0/0.5 and 1.5/0.75 mm). All image data were transferred to a three-dimensional workstation to assess multi-planar reformation (MPR), VR and VGP. Accuracy of volume measurement using the VR technique for quantitative analysis was compared using a paired t-test. Four radiological technologists also independently evaluated the visual score using the VGP technique for qualitative analysis, and their evaluations were compared using one-way analysis of variance with Fisher's protected least significant difference post-hoc test. There was a statistically significant difference in reproducibility between the three different slice thicknesses as to volume measurement and observer performance test (p<0.01 and p<0.05, respectively). Furthermore, the reproducibility improved when using thinner slices. In conclusion, VR and VGP techniques using a slice thickness of 0.8 mm made it possible to maintain accuracy and reproducibility when using CTC to detect polypoid lesions.

Audiological and transient evoked otoacoustic emission findings in patients with vitiligo

Objective To investigate hearing loss in patients with vitiligo. Study Design Case-control study. setting University hospital. subjects and Methods Conventional pure-tone and high-frequency audiometric tests were obtained, and pure-tone average hearing thresholds were calculated for 22 consecutive cases with vitiligo and 22 sex- and age-matched controls. Transient evoked otoacoustic emission testing was also performed. Results There was sensorineural hearing loss on pure-tone audiogram in 16 (36.4%) ears in patients with vitiligo. The hearing thresholds (in dB) were 16.02 ± 6.61 versus 12.39 ± 6.05, 15.68 ± 6.34 versus 13.18 ± 3.75, 15.80 ± 13.93 versus 7.39 ± 6.95, 25.11 ± 17.40 versus 15.91 ± 12.91, 29.89 ± 18.57 versus 17.84 ± 12.36, and 45.91 ± 23.31 versus 33.86 ± 15.99 in the patient and control groups at 0.25, 1, 4, 8, 10, and 12.5 kHz, respectively, and were statistically significantly different. Reduction of transient evoked otoacoustic emission amplitude was statistically significant at 4 kHz in patients with vitiligo (6.34 ± 3.98 dB vs 8.63 ± 5.15 dB, P = 0.023). There was no significant difference in reproducibility, stimulus intensity, stability, and average transient evoked otoacoustic emission amplitudes in patients with vitiligo. Conclusion Hearing thresholds at pure-tone and high-frequency audiometry were higher in patients with vitiligo. Also, significantly lower high-frequency amplitudes were recorded during transient evoked otoacoustic emission testing in the disease group.

Reproducibility of Airway Responsiveness in Horses Using Flowmetric Plethysmography and Histamine Bronchoprovocation

Inflammatory airway disease has a high prevalence in horses, but is often a diagnostic challenge. Flowmetric plethysmography and histamine bronchoprovocation (FP/HBP) is a simple and effective tool for diagnosis, but reproducibility of these measurements made over time has not been established. We hypothesize that the measurement of airway responsiveness in horses using FP/HBP is consistent over both short and long periods of time. Twenty-nine healthy adult horses from 2 university herds. In this prospective experimental study, airway responsiveness was determined in each horse at day 0 (baseline [BL]) with FP/ HBP, using PC35 (provocative concentration of histamine needed to increase Delta(flow) by 35%) as a measure of airway responsiveness. Each horse was re-tested 1-4 weeks after BL (short-term [ST]) and again at 3-12 months after BL (long-term [LT]). In the ST period, 23/27 (85%) of the horses had a PC35 that was within 1 doubling concentration of histamine of their BL value, with a mean change of 0.52 doubling concentrations (95% CI 0.26-0.79, range 0-2.06). For the LT data, 19/26 (73%) of horses were within 1 doubling concentration of their BL value, with a mean change of 0.81 doubling concentrations (95% CI 0.45-1.17, range 0.14-3.10). There was no significant difference in reproducibility between the 2 groups of subjects. Repeated measurements of airway responsiveness obtained with FP/HBP show acceptable reproducibility over time periods up to a year. However, caution must be used when testing horses when ambient air temperature is low.

Comparison of Cemented vs Uncemented Acetabular Component Positioning Using an Imageless Navigation System

Hip navigation was used as an assessment tool to compare ability to reproduce trial and definitive acetabular placement in total hip arthroplasty, using cemented and uncemented components. We demonstrated a significant difference in reproducibility between components. Of 20 uncemented cups, 4 (20%) deviated from the target inclination by 5° or more compared to none of 21 in the cemented group ( P = .048). Of the 20 uncemented cups, 7 (35%) deviated from the target version by 5° or more compared to none of 21 in the cemented group ( P = .003). This may explain higher rates of revision for dislocation with uncemented components. There was also a significant difference between the groups with regard to deviation from planned leg length ( P < .001).

Simultaneous determination of platinum group elements and rhenium in rock samples using isotope dilution inductively coupled plasma mass spectrometry after cation exchange separation followed by solvent extraction

A simple and precise determination method for platinum group elements (PGEs) and Re in rock samples was developed using isotope dilution coupled with inductively coupled plasma mass spectrometry (ID-ICP-MS). Cation exchange separation was employed for simplicity, because it is applicable to group separation and simultaneous isotopic measurement in contrast with the widely used anion exchange separation which entails separate elution. However, its application to ID-ICP-MS has been limited due to spectral interferences from impurities retained in the PGE fraction even after ion chromatography. To overcome this limitation, solvent extraction using N-benzoyl- N-phenylhydroxylamine (BPHA) in chloroform was successfully applied for further purification. After the examination of optimum experimental parameters in cation exchange separation and solvent extraction using synthetic PGE solution, the established procedure was applied to the determination of PGEs and Re in some geochemical reference materials. The obtained results agreed well with the literature data determined using the different digestion methods (NiS fire assay and the use of a high-pressure asher) within the analytical uncertainties of each other. Significant difference in reproducibility between Ru, Ir, Pt and Os group, and Pd and Re group was observed in the results for BHVO-2 and JA-2. By considering the error factors affecting analytical reproducibility, we concluded that the difference is ascribed to the sample heterogeneity of minor minerals enriched in Ru, Ir, Pt and Os.

Comparison of manual and semi-automated delineation of regions of interest for radioligand PET imaging analysis

BackgroundAs imaging centers produce higher resolution research scans, the number of man-hours required to process regional data has become a major concern. Comparison of automated vs. manual methodology has not been reported for functional imaging. We explored validation of using automation to delineate regions of interest on positron emission tomography (PET) scans. The purpose of this study was to ascertain improvements in image processing time and reproducibility of a semi-automated brain region extraction (SABRE) method over manual delineation of regions of interest (ROIs).MethodsWe compared 2 sets of partial volume corrected serotonin 1a receptor binding potentials (BPs) resulting from manual vs. semi-automated methods. BPs were obtained from subjects meeting consensus criteria for frontotemporal degeneration and from age- and gender-matched healthy controls. Two trained raters provided each set of data to conduct comparisons of inter-rater mean image processing time, rank order of BPs for 9 PET scans, intra- and inter-rater intraclass correlation coefficients (ICC), repeatability coefficients (RC), percentages of the average parameter value (RM%), and effect sizes of either method.ResultsSABRE saved approximately 3 hours of processing time per PET subject over manual delineation (p < .001). Quality of the SABRE BP results was preserved relative to the rank order of subjects by manual methods. Intra- and inter-rater ICC were high (>0.8) for both methods. RC and RM% were lower for the manual method across all ROIs, indicating less intra-rater variance across PET subjects' BPs.ConclusionSABRE demonstrated significant time savings and no significant difference in reproducibility over manual methods, justifying the use of SABRE in serotonin 1a receptor radioligand PET imaging analysis. This implies that semi-automated ROI delineation is a valid methodology for future PET imaging analysis.

Comparative study into the robustness of compartmental modeling and model‐free analysis in DCE‐MRI studies

To evaluate and compare the reproducibility of the preferred phenomenological parameter IAUC60 (initial area under the time-concentration curve [IAUC] defined over the first 60 seconds postenhancement) with the preferred modeling parameter (K(trans)), as derived using two simple models, in abdominal and cerebral data collected in typical Phase I clinical trial conditions. Dynamic contrast enhanced MRI (DCE-MRI) time series were acquired at two imaging centers from a group of patients with abdominal tumors and a group with gliomas. At both imaging centers, precontrast T1 was calculated using a variable flip angle three-dimensional spoiled gradient echo acquisition that was used to quantify tissue contrast agent concentration, allowing voxelwise definition of summary DCE-MRI parameters. A comparison of reproducibility showed that there was no statistically significant difference in reproducibility between IAUC60 and K(trans), although there was a trend towards better reproducibility for K(trans) (P = 0.0782). The 95% confidence intervals (CIs) for individual changes showed that for IAUC60 and K(trans), changes in excess of 47% and 31%, respectively, are outside the range of normal variability. Although modeling is more complex and more computationally intensive than an IAUC parameterization, our data suggest this approach to be preferable to a model-free approach since it provides greater physiological insight without a reduction in statistical power for Phase I/II clinical drug trials.

Evaluation of simple non‐invasive techniques for assessment of lower extremity arterial disease

To evaluate the reproducibility and precision of three, simple, non-invasive methods to measure blood pressure (BP) in the lower extremities by comparing reproducibility and sensitivity in finding abnormally low BP between ankle blood pressure (ABP) and toe blood pressure (TBP), by studying the concordance between TBP in toe 1 and 2 and evaluating the pole-pox method in patients with diabetes and lower extremity arterial disease (LEAD). The BP was measured twice, 1 week apart, in arms and legs in 13 controls and 12 patients with diabetes. ABP was assessed by using a Doppler pen for pulse registration. TBP was obtained by using a small cuff and a pulse oximetry sensor at toe 1 and 2. In eleven patients with diabetes and previously known LEAD ABP was obtained through the pole-pox method. No significant difference in reproducibility between absolute BPs and indices (coefficients of variation <9%) was found. A non-significant improvement with 4-8% in the sensitivity in detecting LEAD was seen when BP indices were used instead of absolute BP. A significant correlation in the variation over time for systemic and TBP (r = 0.34, P = 0.015) and a strong correlation was found between TBP measured at toe 1 and 2, respectively (r = 0.99, P < 0.001) was found. TBP measured with pole-pox method were significantly correlated with measurements made by the ordinary cuff technique (r = 0.75, P < 0.001). The use of TBP and ABP indices instead of absolute BP does not improve the reproducibility but may improve the sensitivity with respect to detection of LEAD, especially in patients with diabetes. The pole-pox method may be used as an alternative screening method in patients with diabetes and LEAD.

Reproducibility of Visual Analog Scale (VAS) Pain Scores to Mechanical Pressure

This study tested the reproducibility of visual analog scale (VAS) pain scores to measure changes in masseter muscle pain evoked by maximally tolerable mechanical stimulation over a short time period in healthy subjects. This study also evaluated gender differences in reproducibility of VAS scores to mechanical stimulation. Ten healthy female and eight healthy male individuals participated in this study. The recordings of VAS pain scores to an identical mechanical pressure on the masseter muscle were performed at three different sessions (T1, T2, and T3). The subjects rated their pain on a VAS to a maximally tolerable stimulus that was recorded on an algometer at the first session. The algometer pressure reading was recorded for each subject and then used to duplicate the same identical mechanical stimulus at each of the three sessions. This identical pressure was repeated in the same marked spot at six minutes and after 30 minutes. The subjects rated the pain on a VAS to this identical stimulus at each session. There was no significant difference in VAS pain scores of all subjects at T1, T2, and T3. There was no significant difference in reproducibility of VAS pain scores in females compared to males. Intraclass correlation coefficients were 0.811 on the right masseter and 0.844 on the left masseter. VAS pain scores to mechanical stimulation were reproducible over a short time period. Gender did not affect the reproducibility. This previously unreported method of measuring pain to repeated identical mechanical stimulation appears to have potential for both clinical and research application.

Messung des Augeninnendrucks mit dem Tono-Pen im Vergleich zum Applanationstonometer nach Goldmann - eine klinische Studie an 100 Augen

In clinical practice ophthalmologists often need a tonometer which is independent of a slit lamp. Such a hand-held device is the Tono-Pen. We compared the precision of two equal Tono-Pens with Goldmann applanation tonometry. Measurement of intraocular pressure (IOP) was done in 100 eyes of 51 patients (mean age 63 +/- 15 years) suffering from ocular hypertension or glaucoma. According to a random table either the right or left eye was measured using Goldmann tonometer first and the Tono-Pen second. For the other eye the measurement was reversed. One of the two equal Tono-Pens (Solan/USA) was used according to a second random table. Three measurements were obtained with each instrument on both eyes within 15 minutes subsequently. Patients were placed in an upright position for all measurements. Even for well-trained ophthalmologists a learning curve of approximately 10 measurements was observed using the Tono-Pen. The Tono-Pen measured an average IOP of 16.9 mm Hg in all 100 eyes. The Goldmann tonometer measured an average IOP of 17.7 mm Hg. The difference was not statistically significant. The standard deviation for all measurements was better for the Tono-Pen (4.7 mm Hg vs 5.8 mm Hg for Goldmann tonometer). No reduction of the IOP after Tono-Pen measurement was observed (in contrast to the Goldmann tonometer). The reproducibility of the Tono-Pen on the same eye was inferior to the Goldmann tonometer by a factor of 2. There was an almost significant difference in reproducibility between two equal Tono-Pens. Measurement of IOP with the Tono-Pen is comparable to Goldmann applanation tonometry if an average of 3 measurements is used. The difference between two equal Tono-Pens indicates the need for improvement of the quality check during production.

Diurnal variation in stature: is stretching the answer?

AIMSTo investigate the extent and timing of diurnal variation in stature and to examine the effectiveness of the stretched technique in reducing the loss in height.SETTINGA Southampton school.DESIGNFifty three children,...

The intra- and inter-operator variability of Echo-Doppler measurements for noninvasive pulmonary arterial pressure determination in congenital heart disease

Objective: This prospective study determines reproducibility of measurements derived from the pulmonary arterial (PA) blood flow velocity waveform in infants and children with congenital heart disease by performance of the Doppler echocardiographic examination by different echocardiographers. Additionally, the effect of respiration on reproductibility is investigation. Methods: In group I consisting of 44 consecutive patients (aged 0.1–16.2 years) admitted for echocardiography, the PA blood flow velocity waveform was independently determined by two equally experienced echocardiographers. To obtain intra-operator variability, one performed the examination again. In 38 mechanical ventilated patients (aged 0.2–15.6 years), PA blood flow velocity was examined twice by the same echocardiographer to investigate the effects of respiration on reproducibility (group II). Results: In both groups, no systematic difference between examinations could be shown for all Doppler measurements. In group I, the percentage of absolute difference between echocardiographers ranged from 6.0% to 26.4%. Maximal acceleration and deceleration were least reproducible. In group II, the percentage of absolute difference between successive PA bloodflow velocity waveform determinations ranged from 9.2% to 28.6%. No significant difference in reproducibility between respiratory phases was present for all Doppler measurements. Reproducibility was best in end-expiratory beats. Conclusions: reproducibility of measurements derived from the PA blood flow velocity waveform is low and might explain the conflicting results in non-invasive PA pressure determination. To overcome effects of respiration, selection of end-expiratory beats is reccommended.

Reproducibility and condylar position of a physiologic maxillomandibular centric relation in upright and supine body position

Better understanding of the physiologic features of the masticatory system has led to the evolution of the concept of maxillomandibular centric relation from the mechanical to physiological bases. However, the reproducibility of physiologic methods for centric relation determination has been criticized. In this clinical study the swallowing technique was modified to establish a physiologic centric relation in a reproducible manner. Condylar and disk positioning and reproducibility of the proposed modified swallowing technique (MST) were compared with the same parameters of a traditional technique, namely, the chin point guidance technique (CGT). Both techniques were studied with the patient in the upright and supine positions. Three interocclusal records were obtained for each technique-position combination for each of the 30 patients. The recorded maxillomandibular relations were analyzed on the three-dimensional analyzer. MST positioned the condyles in a more superoanterior position than did CGT, which was interpreted as a better seating of the condyles and disk in the articular fossae. There was no significant difference in reproducibility between MST and CGT on x, y or z axes ( p > 0.05), indicating that it is possible to establish a physiologic centric relation in a reproductible manner. The term “functional centric area” was proposed in this study to define a neuromuscularly determined centric occlusal scheme.

Reproducibility of Optic Nerve Head Topographic Measurements with the Glaucoma-Scope

Our purpose was to evaluate the reproducibility of optic nerve head depth measurements using the Glaucoma-Scope. Optic nerve head topography was measured with the Glaucoma-Scope in 10 normal subjects and in 10 patients with glaucoma. Five separate readings were obtained by a single observer from one eye of each subject on the same day. Mean depth values were calculated for the overall disc, each quadrant, and areas overlying vessels at those points at which the change from baseline exceeded 50 mum. Similar calculations were made for actual depth measurements in regions of potential clinical interest, including the bottom of the cup, the temporal slope, the nasal disc, and a peripapillary region, as well as 15 randomly selected single points. Reproducibility of the depth values was determined by calculating standard deviations, coefficients of variation, and 95% confidence intervals in the five separate measurements. The mean standard deviations in regions of potential clinical interest among the 20 subjects ranged from 3.98 mum to 14.09 mum, and the mean coefficient of variation ranged between 4.2% and 8.7%. The 95% confidence intervals for the total population ranged from 9.88 mum to 34.97 mum for the regions of interest and was 43 mum for the 15 random points. There was no statistically significant difference in reproducibility between the two groups of subjects. In this study the Glaucoma-Scope produced quantitative optic nerve head topographic measurements that were highly reproducible, within a tolerance of <50 mum.

The reproducibility of pantographic tracings on medicated and nonmedicated subjects

Tracings were made on three patients using a modified pantographic device. The tracings were made on glass flags with wax, etched, and superimposed. The effects of body position and modification were investigated. From this research project the following can be concluded: 1. A precise method has been developed which permits superimposition of pantographic tracings for analysis. 2. There is a significant difference in reproducibility between medicated and nonmedicated subjects. 3. The percentage coincidence of border tracings increases significantly when the patient is pantographed while under the influence of medication (Valium). 4. The angulation of the body does not appear to be significant for reproducing border tracings. 5. There appears to be no significant difference in the reproducibility of the border tracings relative to time (1, 1 1/2, 2, and 2 1/2 hours) after medication. 6. The lateral side shift of the jaw cannot always be reproduced accurately. 7. The neuromusculature appears to be the overriding factor governing border movements.