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Results for “Repeatability and Reproducibility”

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PubMed1978

Spectrophotometric determination of pyrantel tartrate in swine feeds by method of standard additions: collaborative study.

The spectrophotometric method for pyrantel tartrate in swine feeds was collaboratively studied. Twenty-seven laboratories assayed feeds containing 0.0103, 0.0965, and 0.7902% pyrantel tartrate. Repeatability (sigmao) and reproducibility (sigmax) standard deviations were: sigmao = 0.00068%, sigmax = 0.00105% (10% of grand mean) for 0.0103% pyrantel tartrate level; sigmao - 0.0065%, sigmax = 0.0090% (10% of grand mean) for 0.0965% pyrantel tartrate level; and sigmao = 0.0415%, sigmax = 0.0743% (10% of grand mean) for 0.7902% pyrantel tartrate level. The mean theoretical recovery values for feeds containing 0.0103, 0.0965, and 0.7902% were 100, 97, and 96%, respectively. The method was adopted as official first action for feeds or concentrates containing 0.0106-0.8811% pyrantel tartrate.

Animal Feed↗

PubMed1983

Direct measurement of apoprotein C-III specific activity in 125I-labeled very low density lipoproteins using immunoaffinity chromatography.

We have developed a technique for isolating apoprotein C-III by immunoaffinity chromatography, allowing the measurement of its specific radioactivity in lipoprotein fractions from small plasma samples. IgG specific for apoC-III was purified from goat antisera and bound to Sepharose. One ml of this gel (5 mg of IgG) bound 80-90 micrograms of apoC-III. The specific activity of apoC-III was determined by application of delipidated very low density lipoproteins to 1-ml columns and analysis of the protein eluted at pH 2.5 for mass and radio-activity. The coefficient fo variation for apoC-III specific activity determination from 125I-labeled VLDL was 4.3%. Minimal contamination of the eluates by apoproteins B, E, and C-II was confirmed by radioimmunoassay (0.3-1.2%). Following the injection of autologous 125I-labeled VLDL, specific activity decay curves for VLDL apoC-III were biexponential, with the clearance of apoC-III being slower in hypertriglyceridemic subjects. These affinity columns can be used repeatedly and yield reproducible results. This technique should be useful for simultaneous studies of the turnover of several apoproteins in the same individual following a single injection of labeled autologous lipoprotein.

Apolipoprotein C-III↗

PubMed1983

[Repetitive skin testing in patients with lower leg eczema and leg ulcer].

16 patients with lower leg dermatitis and venous ulcers had been subject to patch-testing during 1974 to 1977. When retested in 1982, the number of positive reactions per patient increased from 3.82 to 5.87 on an average. 54% of the positive epicutaneous test reactions could be reproduced in the repeated patch test. Meanwhile, 9 of 16 of patients were free of lower leg dermatitis and 8 of them were free of venous ulcers. This paper deals with the problematic nature as well as the likely causes of the apparent inconsistency of epicutaneous test reactions in patients with lower leg dermatitis and venous ulcers.

Allergens↗

PubMed1995

[Diagnosis of coronary heart disease using echocardiography 3D reconstructions. Diagnosis of global and regional left ventricular function].

The technique of tomographic 3D-echocardiographic reconstructions allows, beside the morphological description of cardiac structures, a left ventricular quantification concerning the diagnosis of the coronary heart disease. The advantage of the tomographic 3D-reconstruction and tomographic quantification is that the left ventricular volume is determined directly by manual planimetry during the whole heart cycle and will not be approximated by geographical algorithms as used for 2D-techniques and alternative 3D-techniques. We worked with the Echoscan reconstruction unit (TomTec) equipped with a pentium-processor and a 64 RAM memory for the acquisition and digitalization of a 3D-echocardiographic image data set (Figures 2a and 2b). Automatic image acquisition is performed using a unit existing of a common ultrasound transducer and a special rotational motor device. All the examinations described in this publication are performed by a transthoracic approach. Examining asymmetric model hearts with aneurysm an experimental study sustentiated the high accuracy of determining asymmetric ventricle volumes (mean of difference [3D--true dimensions] = 0.91 ml; SD of differences = +/- 6.17 ml) and aneurysm volume (mean of difference = 0.43 ml; SD of difference = +/- 2.14 ml). Also high reproducibility of 2 repeated 3D-measurements was documented (ventricular volumetry: mean of difference = -0.09 ml; SD of difference = 3.15 ml. Aneurysm volumetry: mean of difference = 0.24 ml; SD of difference = 0.17 ml). The principle of quantification by tomographic planimetry is usable the same way in vivo (Figures 3 and 4).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Volume↗

PubMed1995

Continuous occlusion test to determine detrusor contractile performance.

PURPOSE: A study was conducted to determine the merits of the continuous occlusion test as a method of detrusor contractility assessment by comparing it with other stop tests and with contractility derived from pressure-flow analysis. MATERIALS AND METHODS: The continuous occlusion test was performed in elderly men by occluding the bladder outlet before the onset of a detrusor contraction and it was repeated to assess reproducibility. The magnitude of the isovolumetric contraction, maximum slope of the detrusor contraction, and duration of detrusor activation were determined. Voluntary and mechanical stop tests were performed during the mid voiding phase. Continuous occlusion test parameters were compared with the pressure-flow contractility parameters. RESULTS: The continuous occlusion test was evaluated in 159 patients. The maximum isovolumetric contraction pressure of the continuous occlusion test was significantly higher than that of the voluntary stop test (49 patients). Continuous occlusion test contractility parameters were reproducible. The maximum isovolumetric contraction pressure and the maximum slope of the detrusor contraction of the continuous occlusion test significantly correlated with the estimated maximum isovolumetric contraction pressure and estimated velocity of shortening (derived from pressure-flow), respectively (r = 0.79, p < 0.0001 and r = 0.385, p = 0.016, 39 patients). The watts factor was well correlated with maximum isovolumetric contraction pressure (r = 0.75, 39 patients). CONCLUSIONS: Our study suggests that the continuous occlusion test can be used as an effective alternative method of assessing detrusor contractility.

Adult↗

PubMed1994

191Os/191mIr-generator for studying arterial blood flow in experimental animal models.

Iridium-191m (191mIr, t1/2 = 4.96 sec), an ultra-short lived tracer, has turned out to be suitable for gamma imaging. It can be obtained in high yields from an 191Os/191mIr-generator with a low 191Os breakthrough. In this study the blood flow in the carotid and kidney arteries was studied in rabbits by radionuclide arteriograms. In addition, the whole body retention and biodistribution of 191Os was studied in rats. 191mIr was obtained from an activated carbon system, in a modification of the procedure described in the literature. The kidney regions (study I) of rabbits were imaged dynamically (5 frames/second) for up to 40 seconds, and the investigations were repeated 4-7 times in the same animal. Similarly, the carotid arteries were studied (study II) and from the curves flow parameters were calculated. In order to study the 191Os breakthrough two groups of rats (n = 5) were sacrificed one day and four days after injecting five diagnostic doses into the tail vein (study III). In study III the Os-retention was highest in the kidneys and spleen, followed by the muscles and liver: 0.11-0.12% ID/g tissues were obtained at 1 day and 0.10-0.13% ID/g at 4 days, respectively. These values indicate that the breakthrough values are by no means toxic and that investigations can be repeated immediately with a negligible radiation exposure. The investigations performed with the same animals (I-II) could be easily repeated and were reproducible. All of this indicates that 191mIr is suitable for radionuclide angiography and the generator system is simple and safe to use (191Os is beta-emitter).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Enzyme-linked immunosorbent assay for detection of zearalenone in corn, wheat, and pig feed: collaborative study.

A direct competitive enzyme-linked immunosorbent assay (ELISA) screening method for zearalenone in corn, wheat, and feed at 500 ng/g was evaluated by 23 collaborators (22 laboratories) in an international collaborative study. Eighteen samples of spiked or naturally contaminated corn, wheat, and pig feed were prepared by the sponsoring laboratory and sent for testing with complete test kits to participating collaborators in Canada, Italy, Sweden, The Netherlands, and the United States. Test samples were extracted with methanol-water solution (70 + 30) by shaking on a wrist-action shaker for 3 min. A portion of the extract was mixed with an equal volume of zearalenone-enzyme conjugate, and the mixture was incubated with zearalenone-specific monoclonal antibodies coated onto microtiter wells. All test samples were assayed in duplicate. One of 52 (2%) blanks was reported positive. Thirty-nine of the 52 (75%) samples that were spiked at 500 ng/g were reported as positive. Forty-nine of the 51 (96%) samples with concentrations at or above 1000 ng/g were reported as positive. The overall incidence of false negatives was 6.0% and the incidence of false positives was 22.7% by the ELISA method. Only one (3.4%) false negative was reported for samples containing > or = 800 ng/g. In the spectrophotometric method, 8 collaborators determined approximate levels of zearalenone in test samples from standard curves constructed from spiked extracts (0-3000 ng/g of each commodity tested). This method gave and overall incidence of false negatives of 5.7% and false positives of 17.8%. Average relative standard deviations, RSDr (repeatability) and RSDR (reproducibility), were 11.6 and 25.1% for spiked samples and 11.7 and 33.1% for naturally contaminated samples, respectively. Standard curves were constructed with each set of samples assayed. Comparison of absorbance values from these standard curves indicate the performance of reagents and antibody used in the assay. The ELISA method has been adopted first action by AOAC INTERNATIONAL as a screening method for zearalenone at > or = 800 ng/g in corn, wheat, and pig feed.

Animal Feed↗

PubMedDate not supplied

Analysis of milk-based infant formula. Phase IV. Iodide, linoleic acid, and vitamins D and K: U.S. Food and Drug Administration-Infant Formula Council: collaborative study.

In 1982, the U.S. Food and Drug Administration, the Infant Formula Council and its member companies, contract laboratories, and other government laboratories began a study of analytical methods for the nutrients listed in the Infant Formula Act of 1980. Phases I, II, III, and V have been completed. The present report provides data on Phase IV, in which 13 laboratories collaboratively studied an ion-selective electrode method for analyzing iodide, a gas chromatographic method for linoleic acid, and 2 liquid chromatographic (LC) methods each for vitamins D and K. Data were insufficient to evaluate one each of the LC methods studied for vitamins K and D. The relative standard deviations (RSD) are sufficient for the nutrient levels found in infant formula. RSDs (%) for repeatability (RSDr) and reproducibility (RSDR), respectively, were as follows: iodide, 4.0-11.4 and 13.5-18.2; linoleic acid, 1.0-1.6 and 3.5-5.1; vitamin K1, 3.2-16.0 and 6.2-19.4; and vitamin D3, 4.2 and 35.0. The recommendation to adopt the method for vitamin D was supported by the results of a ministudy. All laboratories were capable of using these methods with little training. The methods for determination of iodide, linoleic acid, and vitamins D and K in ready-to-feed milk-based infant formula have been adopted first action by AOAC International.

Chromatography, Gas↗

PubMedDate not supplied

Analysis of milk-based infant formula. Phase V. Vitamins A and E, folic acid, and pantothenic acid: Food and Drug Administration-Infant Formula Council: collaborative study.

In 1982, the U.S. Food and Drug Administration, the Infant Formula Council and its member companies, contract laboratories, and other government laboratories began a study of analytical methods for the nutrients listed in the Infant Formula Act of 1980 (P.L. 96-359). Four phases of the study have been completed and are discussed in earlier reports. The present report provides data on Phase V, in which 13 laboratories collaboratively studied individual methods for folic acid, pantothenic acid, and vitamin E, in addition to 2 methods for vitamin A. Vitamins A and E are determined by liquid chromatography. Folic acid and pantothenic acid are determined by microbiological methods using acidimetric and/or turbidimetric assays as the determinative step. In most cases, relative standard deviations for repeatability, RSDr, and reproducibility, RSDR, are as good as those that would be predicted from other collaborative studies. RSDr and RSDR values obtained for the 5 methods are 9.35 and 25.44% for folic acid, 4.59 and 10.23% for pantothenic acid, 8.46 and 11.69% for vitamin E, 3.62 and 9.72% for vitamin A (retinol isomers), and 4.9 and 10.5% for vitamin A (retinol). The 5 methods have been adopted first action by AOAC International.

Animals↗

PubMed1996

Potassium channel modulation: a new drug principle for regulation of smooth muscle contractility. Studies on isolated airways and arteries.

K+ channels play a key role in regulation of membrane potential and cell excitability. Several different types of K+ channels have been identified and the presence, characteristics and functions of these channels vary among different tissues. The 3 most important K+ channels in smooth muscle are the KATP (activated by a fall in intracellular ATP and a rise in nucleotide diphosphates and blocked by glibenclamide), BKCa (activated by a rise in intracellular Ca2+) and Kv (activated by depolarization). Cromakalim, pinacidil and nicorandil are members of a rapidly increasing group of novel drugs which open K+ channels. Opening of such channels leads to K+ efflux, membrane hyperpolarization, reduced excitability and smooth muscle relaxation. The purpose of the studies included in this thesis was to investigate this novel drug principle of K+ channel modulation on smooth muscle contractility of isolated airways and arteries and on neuroeffector transmission in airways. Smooth muscle contractility was measured in airway and vascular ring preparations suspended in isometric myographs. Neurotransmitter release was elicited by transmural electrical field stimulation. The major findings were: 1) Membrane depolarization by high extracellular K+ concentrations induced contraction of airway smooth muscle that was easily relaxed by Ca2+ antagonists and abolished in a Ca2+ free medium indicating that K+ contraction is triggered by Ca2+ influx through voltage-operated Ca2+ channels. Indomethacin was required to obtain reproducible responses upon repeated exposure to K+ suggesting that endogenous prostaglandins are released by K+ and interferes with its contractile effect. K+ depolarization was shown to be a valuable pharmacological tool for detection of drugs acting by K+ channel opening. The prototype K+ channel opener cromakalim relaxed contractions induced by 20-30 mM K+ but had no effect against contraction induced by 124 mM K+. This was a unique profile of action not shared by other types of airway and vascular smooth muscle relaxants. As the extracellular K+ concentration is raised the outward directed electrochemical gradient for K+ is reduced and at high K+ concentrations the effect of K+ channel opening is negligible. Although the K+ channel opener pinacidil had a higher relaxant potency against contraction induced by 30 mM K+ than by 124 mM K+, it still relaxed the latter contraction indicating an additional K+ channel independent mechanism of action of the drug. When K+ depolarization is used as a pharmacological tool, it is essential to maintain osmolarity. Addition of KCI directly to the tissue bath solution, which previously was a commonly applied technique, produced confounding and unwanted effects due to hyperosmolarity per se. 2) Pinacidil and cromakalim relaxed guinea-pig trachea either tone was spontaneous or induced by a range of airway spasmogens (histamine, PGF2 alpha, LTC4/LTD4 or carbachol) of relevance as asthma mediators. The relaxant effectiveness of the drugs was reduced when tone was elicited by carbachol. The airway smooth muscle relaxation produced by pinacidil and cromakalim was selectively blocked by the antidiabetic sulfonylureas glibenclamide, glipizide and glibornuride and also by phentolamine. These drugs are blockers of KATP which therefore indicates that this channel is the target for cromakalim and pinacidil in airway smooth muscle. Additional to the antagonistic action against K+ channel openers the sulfonylurea KATP blockers and phentolamine at higher concentrations relaxed airway smooth muscle by yet unknown mechanisms that seemed unrelated to KATP. 3) Cromakalim and pinacidil inhibited nerve-mediated e-NANC contractile responses in guinea-pig bronchi. Such responses are due to release of SP and related tachykinins from sensory nerve endings. These neuropeptides cause bronchoconstriction and airway inflammation and may possibly play an important role in the pathophysiology of asthma.

Animals↗

PubMedDate not supplied

[Secondary infection with hepatitis A in Rhesus monkeys after experimental inoculation].

Time course of specific humoral immunity is studied in 186 Macaca mulatta spontaneously infected with hepatitis A virus (HAV). Immunity parameters are characterized quantitatively and qualitatively and their similarity to those in human hepatitis A (HA) is demonstrated. Repeated HA was reproduced in 12 seropositive Macaca mulatta infected with HAV-MR in high doses. The disease was characterized either by periodical virus release with feces for 1.5-2 months (10(4) ID50) or by that together with a notable increase of SGPT for 1.5-4 months (10(5) ID50) without morphologic changes in the liver, indicating a lesser severity of infection. Reinfection was associated with a rapid expressed increase of class G anti-HAV titers to 20,000-74,000 and no class M antibodies. Virus release with feces in the absence of the main specific diagnostic criterion, IgM antibodies, may be epidemiologically significant. Hyperimmune sera from monkeys with reinfection are intended to be used as the antibody component of immune diagnostic agent.

Animals↗

PubMed2000

Reproducible biphasic cutaneous edema induced by topical and repeated application of antigen in sensitized mice.

An allergic dermatitis model was developed by repeated sensitization and challenge with antigen (ovalbumin, OA) over 7 months in mice. ddY mice were sensitized by i.p. injection of OA adsorbed on Al(OH)3 (1 microg OA/2 mg Al(OH)3/animal) once every 3 weeks. Antigen challenge was conducted by injection of OA solution (0.1, 1 and 10 microg/site) into the skin of the hind paw instep 10 d after the respective sensitizations. At the 1st challenge, all the 3 groups showed an immediate edematous response with the peak at 30 min or 1 h after the challenge. The group challenged with the highest dose (10 microg/site) of the antigen developed a clear late-phase edema, which was observed at the 2nd challenge, increasing until the 3rd challenge, reaching a plateau at further challenges. On the other hand, such late phase edema scarcely developed in the group challenged with the lowest dose (0.1 microg/site) of the antigen. The amount of circulating specific IgE antibody increased following repeated sensitizations and challenges in all groups, but there were no significant differences in the levels among them. Mepyramine suppressed the early edema by approximately 50%, yet the late phase edema was unaffected. In conclusion, using Al(OH)3+antigen for sensitization and an appropriate amount of antigen for challenge, reproducible biphasic edematous responses were observed long-term without desensitization. This model may be classified as an acute allergic dermatitis and can be useful for quantitatively evaluating the effects of anti-allergic drugs.

Animals↗

PubMed1994

Simultaneous assessment of vasoreactivity using transcranial Doppler ultrasound and cerebral blood flow in healthy subjects.

Blood flow velocities in both middle cerebral arteries and regional cerebral blood flow in their perfusion territories were measured simultaneously in 36 healthy subjects. In 20 subjects, the measurements were first performed under basal conditions and then repeated 15-20 min after an intravenous injection of 1 g of acetazolamide. Reproducibility of simultaneous blood flow and velocity measurements was tested by examining 16 subjects on two occasions under basal conditions with an interval of 20 min. Relatively good reproducibility was found for repeated measurements of velocity and blood flow, being best when side-to-side asymmetry was assessed. The increase in blood flow velocities after acetazolamide was symmetrical (right side, 34.2%; and left side, 35.5%), and the velocity increase was significantly correlated with basal values. The increase in cerebral blood flow was also symmetrical (right side, 29.8%; left side, 30.1%) but not correlated with basal flow values. No significant relationship was found between velocity increase and increase in regional cerebral blood flow. This finding is probably not only due to methodological inaccuracies but may suggest that acetazolamide has an effect on the diameter of the middle cerebral artery or on the magnitude of this artery's perfusion territory. This study supports the use of acetazolamide for assessing cerebral vasoreactivity following the definition of lower limits for velocity and flow increase and for asymmetry of the response.

Acetazolamide↗

PubMed2006

Towards standard methods for the detection of Cryptosporidium parvum on lettuce and raspberries. Part 2: validation.

We report the results of interlaboratory collaborative trials of methods to detect oocysts of the protozoan parasite Cryptosporidium parvum on lettuce and raspberries. The trials involved eight expert laboratories in the United Kingdom. Samples comprised 30 g lettuce, and 60 g raspberries. Lettuce samples were artificially contaminated at three levels: low (8.5-14.2 oocysts), medium (53.5-62.6 oocysts), and high (111.3-135.0 oocysts). Non-contaminated lettuce samples were also tested. The method had an overall sensitivity (correct identification of all artificially contaminated lettuce samples) of 89.6%, and a specificity (correct identification of non-contaminated samples) of 85.4%. The total median percentage recovery (from all artificially contaminated samples) produced by the method was 30.4%. The method was just as reproducible between laboratories, as repeatable within a laboratory. Raspberry samples were artificially contaminated at three levels: low (8.5-26.8 oocysts), medium (29.7-65.7 oocysts), and high (53.9-131.3 oocysts). Non-contaminated raspberry samples were also tested. The method had an overall sensitivity (correct identification of all artificially contaminated raspberry samples) of 95.8%, and a specificity (correct identification of non-contaminated samples) of 83.3%. The total median percentage recovery (from all artificially contaminated samples) produced by the method was 44.3%. The method was just as reproducible between laboratories, as repeatable within a laboratory. The results of the collaborative trial indicate that these assays can be used effectively in analytical microbiological laboratories.

Animals↗

PubMedDate not supplied

Multiple reproducibility indices for evaluation of cognitive functional MR imaging paradigms.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate a variety of reproducibility indices for cognitive functional MR imaging (fMRI) paradigms that account for both overlapping and extraneous regions of activation. METHODS: Eight right-handed volunteers were imaged with fMRI by using a word-generation paradigm and a forward-backward text-listening paradigm. The paradigms were performed twice in the session and repeated 1 week later. Reproducibility indices for the four repeated studies were determined on the basis of pair-wise computation of the ratio of the probability-weighted intersection volume divided by the union volume of surviving activation clusters. The intersection volume was determined by using several iterations of the morphologic dilatation operator with additional voxels accrued in the intersection weighted by an exponential function. Computed indices included global reproducibility, language area reproducibility, extraneous activation reproducibility, and laterality. RESULTS: The word-generation paradigm had reproducibility values that were significantly greater than those of the forward-backward text-listening paradigm (global reproducibility, 0.75 vs 0.5, P <.005; language area reproducibility, 0.85 vs 0.6, P <.008; mean extraneous activation reproducibility, 0.68 vs 0.41, P <.002). The forward-backward text-listening paradigm demonstrated more focal activations, whereas the word-generation demonstrated larger activations outside the dominant language areas that were highly reproducible. CONCLUSION: For clinically relevant language paradigms, multiple reproducibility indices should be taken into account in selecting an appropriate paradigm. Compared with a forward-backward text-listening task, a word-generation task has higher reproducibility indices at the expense of localizing ability. The forward-backward paradigm demonstrates more focal activations with less extraneous activation.

Adult↗

PubMedDate not supplied

Combination of total solids determined by oven drying and fat determined by Mojonnier extraction for measurement of solids-not-fat content of raw milk: collaborative study.

Each of 9 laboratories analyzed 9 pairs of blind duplicate raw milk samples for fat, using the Mojonnier ether extraction method (16.E13-16.E17), and for total solids, using a new direct forced air oven method. Solids-not-fat was determined by subtracting percent fat from percent total solids. The solids-not-fat content of the samples tested in the collaborative study ranged from 8.48 to 9.36%. The average repeatability standard deviation (sr) and the average reproducibility standard deviation (SR) for the solids-not-fat method were 0.019 and 0.041, respectively. Average repeatability (RSDr) and reproducibility (RSDR) relative standard deviations were 0.218 and 0.466%, respectively. The mean repeatability value (r) was 0.055; the mean reproducibility value (R) was 0.117. The difference between milk total solids determined by direct forced air oven drying and milk fat determined by Mojonnier ether extraction has been approved for interim official first action for determination of solids-not-fat content of milk.

Animals↗

PubMed2002

Triplet repeat DNA structures and human genetic disease: dynamic mutations from dynamic DNA.

Fourteen genetic neurodegenerative diseases and three fragile sites have been associated with the expansion of (CTG)n (CAG)n, (CGG)n (CCG)n, or (GAA)n (TTC)n repeat tracts. Different models have been proposed for the expansion of triplet repeats, most of which presume the formation of alternative DNA structures in repeat tracts. One of the most likely structures, slipped strand DNA, may stably and reproducibly form within triplet repeat sequences. The propensity to form slipped strand DNA is proportional to the length and homogeneity of the repeat tract. The remarkable stability of slipped strand DNA may, in part, be due to loop-loop interactions facilitated by the sequence complementarity of the loops and the dynamic structure of three-way junctions formed at the loop-outs.

DNA↗

PubMed1985

Observer reproducibility during computer-assisted planimetric measurements of nuclear features.

To evaluate observer variance during microprocessor-assisted planimetry, nuclear features (area, perimeter, and form factor) were studied in a series of mammary ductal carcinomas. Fragments of formalin-fixed, paraffin-embedded tissue were re-embedded in plastic, sectioned at 1 micron, stained with methylene blue, and studied with a Zeiss-Kontron MOP-3 microprocessor-assisted planimeter. Both interobserver and intraobserver reproducibility were evaluated, the former among three different observers and the latter by two observers repeating their own measurements. Reproducibility was good for measurement of area, but deteriorated progressively for measurement of perimeter and form factor. Not only was observer correlation poor (identified via linear regression), but paired t-tests also showed consistent variation among observers. The major difficulty was in following the irregular nuclear contours that are characteristic of cancer cells. It is concluded that adequate demonstration of observer reproducibility remains an essential part of tissue investigation, even when the objective methods typical of morphometry are used.

Breast Neoplasms↗