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Results for “method comparison”

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PubMed2002

Evaluation of sputum staining by modified cold method and comparison with Ziehl-Neelsen and fluorochrome methods for the primary diagnosis of tuberculosis.

An improved acid-fast staining technique for sputum examination for the primary diagnosis of tuberculosis is described. The technique was modified and simplified by the elimination of heating and by combining the stages of counterstaining: making the technique easier and safer, with less risk of phenol aerosols. The efficiency of this method was evaluated by comparison with two conventional methods, Ziehl-Neelsen (ZN) staining and fluorochrome staining; culture was deemed the gold standard for tuberculosis diagnosis. Of the 392 sputum samples examined, 22.7%, 19.4% and 22.9% were positive by the ZN, fluorochrome and modified cold (MC) staining methods respectively. In comparison with culture results, the sensitivities of ZN, fluorochrome and MC methods were 68.9%, 59.7% and 70.6% respectively; the specificities were 97.4%, 98.2% and 97.8% respectively and the efficiencies were 88.8%, 86.5% and 89.5% respectively. The fluorochrome method was statistically less sensitive than the ZN and MC (p < 0.05), but no significant differences between the ZN and MC were found (p > 0.05). The results of the MC and ZN methods were in close agreement (97.2%); the slides stained by these techniques could be stored for a long time and the staining reagents were stable for several weeks. In conclusion, the MC method proved to be a valuable alternative to ZN staining for the primary diagnosis of tuberculosis.

Fluorescent Dyes↗
PubMed1991

Calibration of Technicon Chem 1 multitest analysers.

Recently, two Technicon Chem 1 multitest clinical chemistry analysers were introduced after an evaluation in our laboratory. Calibration according to the instructions of the manufacturer resulted in significant differences between the assay results of the two Chem 1 analysers for twelve of twenty-two methods. To remove these differences we used an additional procedure based on the NCCLS EP-9P protocol for method comparison. Four reference methods were used as comparison methods. Our results indicate that, for three of these methods, the results on both Chem 1 analysers are biased in slope and intercept, and corrections of these parameters are necessary to produce results comparable to the reference method values. For the remaining eighteen assays, methods in routine use in our laboratory were used as comparison methods. In fifteen of eighteen assays, corrections of slope and (or) intercept were necessary to prevent changes in the cumulative average patient data produced by our laboratory. An adjustment of the slopes and intercepts, according to the multi-point calibration procedure presented here, resulted in significant differences between system-specific values measured in our laboratory and those assigned by the manufacturer for ten of thirteen methods. We conclude that the use of the multi-point calibration procedure presented in this article (based on calibration according to the instructions of the manufacturer and NCCLS EP-9P) greatly improves the intra-laboratory comparability and therefore should be part of multi-centre evaluations.

Autoanalysis↗
PubMedDate not supplied

Comparison of six respirator fit-test methods with an actual measurement of exposure in a simulated health care environment: Part III--Validation.

This article, the last in a series of three, describes the validation phase of a study conducted to test the correlation of respirator fit factors to the subject's actual exposure using biological sampling. The study consisted of three phases: protocol development, method comparison testing, and validation. Six quantitative fit-test methods were evaluated in the method comparison testing phase. The two fit methods with the highest correlation with the wearers' measured exposure were a corn oil method (R2 = 0.81) and an ambient aerosol method (R2 = 0.78). Because the ambient aerosol method is more commonly used in the workplace, it was selected for further analysis. In this validation phase, the fit factors measured during the ambient aerosol fit-test were used to calculate the exposures to Freon-113 by using the model determined in the method comparison testing phase of the study. The actual Freon-113 exposures were then measured and compared with the predicted exposures. The results verified that the ambient aerosol method fit factors are highly correlated to the total Freon-113 exposure dose and thus that the model had a predictive ability.

Air Pollutants, Occupational↗
PubMed1997

A comparison of three standard methods of identifying mast cells in endobronchial biopsies in normal and asthmatic subjects.

Reported mast-cell counts in endobronchial biopsies from asthmatic subjects are conflicting, with different methodologies often being used. This study compared three standard methods of counting mast cells in endobronchial biopsies from asthmatic and normal subjects. Endobronchial biopsies were obtained from atopic asthmatic subjects (n = 17), atopic nonasthmatic subjects (n = 6), and nonatopic nonasthmatic control subjects (n = 5). After overnight fixation in Carnoy's fixative, mast cells were stained by the short and long toluidine blue methods and antitryptase immunohistochemistry and were counted by light microscopy. Method comparison was made according to Bland & Altman. The limits of agreement were unacceptable for each of the comparisons, suggesting that the methods are not interchangeable. Coefficients of repeatability were excellent, and not different for the individual techniques. These results suggest that some of the reported differences in mast-cell numbers in endobronchial biopsies in asthma may be due to the staining method used, making direct comparisons between studies invalid. Agreement on a standard method is required for counting mast cells in bronchial biopsies, and we recommend the immunohistochemical method, since fixation is less critical and the resultant tissue sections facilitate clear, accurate, and rapid counts.

Adolescent↗
PubMed2000

Producing a full-scale model from computed tomographic data with the rapid prototyping technique using the binder jet method: a comparison with the laser lithography method using a dry skull.

Rapid prototyping using the binder jet method has recently been established and has already produced excellent results in industrial applications. The authors recently developed a technique for producing a full-scale model from computed tomographic (CT) data with the binder jet method as an approach to overcome the shortcomings of the laser lithography method, which is already widely used in medicine. They conducted a comparative investigation of full-scale models made with both techniques using a dry skull to determine the accuracy of the models. It was clearly demonstrated that the accuracy of the binder jet method was high enough to be used in craniomaxillofacial surgery because it was the same as the laser lithography method. This study employed data from the latest helical volume scan computed tomography device using a multidetector. The study showed that the new rapid prototyping technique was satisfactory in terms of speed, cost, installation environment, and accuracy of models, and that detailed shapes and structures can be reproduced well. Because this technique has many advantages over the laser lithography method, it should play a major role in craniomaxillofacial surgery and in other medical fields in combination with advances in CT devices. Although plaster is a more suitable fixation material when the emphasis is on the reproducibility of detailed structures, the binder jet method using starch is extremely useful for simulating operations and determining implant shapes because it allows for the prompt production of models.

Analog-Digital Conversion↗
PubMed1998

[Evaluation of pyuria by means of urinary sediment method--a comparison to the counting chamber method].

We compared the urinary sediment method to counting chamber method in evaluating pyuria, in order to elucidate an issue of urinary sediment method. The KOVA system was used for counting chamber method. Three hundred and ten urine specimens from the patients who visited Fuji City Central Hospital in March, 1995, were employed. The numbers of leukocytes of each specimen was counted by means of urinary sediment method and counting chamber method, and compared. The urinary leukocyte count evaluating by means of these two methods were correlated well. However, the discrepancy of urinary leukocyte counts by means of these two methods were recognized in two specimens. In these two specimens, the leukocyte count was 1 to 4/5HPF by means of urinary sediment method, but more than 50/microliter by means of counting chamber methods. Significant bacteria (10(4) cfu/ml or more), positive esterse reaction, and high pH (8.5) were recognized in both specimens. In addition, one of two these specimens was hypotonic (specific gravity was 1.008). Therefore, it was suggested that leukocytes were sometimes disrupted with centrifugation. These results indicate that counting chamber method is more useful urinary sediment method to detect pyuria.

Adolescent↗
PubMed1983

A comparison of methods of cardiac output measurement.

Cardiac output measurements determined by dye dilution, iced-injectate thermodilution and room temperature thermodilution were compared in man in order to assess the random error of each method and to examine the systematic error of both thermodilution methods in comparison with dye dilution. Results showed that random error was greatest with room temperature thermodilution and least using iced thermodilution. Iced thermodilution correlated well with dye dilution, tending to overestimate cardiac output only at low flows. Room temperature thermodilution, however, overestimated cardiac output by up to 25% in the clinically important range and more so at low cardiac output.

Cardiac Output↗
PubMed1983

Diffusion barriers in skin--a new method of comparison.

Using a method which allows the net barrier potential of skin to be expressed in terms of a 'penetration half-life', skin barriers to nandrolone and allyl oestrenol penetration were compared in human, rat and hamster skin. The ranking order in terms of the net barrier was: human = haired rat greater than or equal to hairless rat greater than hairless hamster. Using the same principles, the net barrier effects of the various layers in whole human skin were also compared. The dermis was only slightly less effective than the stratum corneum as a barrier to diffusion.

Allylestrenol↗
PubMed2002

Evaluation of new oxidation methods for the measurement of bilirubin on the aeroset clinical chemistry analyzer and comparison with methods on the Hitachi 717.

We evaluated analytical and performance quality of the new oxidation methods for direct and total bilirubin on the Abbott Aeroset clinical chemistry analyzer. Within-day imprecisions for Abbott Aeroset assays ranged from 0.7 to 2.9% and between-day imprecisions from 2.1 to 7.3%. Inaccuracies as compared with the control "target values" for the Jendrassik-Gróf method showed deviations of -18.2 to +4.2%. Limits of detection were determined and showed very low values of < or = 0.25 micromol/l and dilution linearities were confirmed up to > 300 micromol/l. A method comparison for 100 patient samples with established Jendrassik-Gróf and DPD methods on the Roche Hitachi 717 showed good linearities between the investigated methods (r > or = 0.995). Due to slopes that ranged from 0.829 to 0.950, reference ranges for the oxidation methods differ slightly from those of established Roche Jendrassik-Gróf methods, but results can be adapted by the introduction of converting factors. In conclusion, the oxidation bilirubin assays revealed convincing analytical and performance qualities for medical needs that were similar or even better than for established methods. Application of the oxidation methods on the Aeroset clinical chemistry analyzer also improves laboratory efficiency by increasing throughput, speed of obtaining results and lowered sample and reagent volumes compared to established methods.

Bilirubin↗
PubMed2001

Alkaline phosphatase activity: new assay for the Reflotron system. Results of the evaluation in eight clinical laboratories.

A new reagent carrier, Reflotron ALP, has been developed for the Reflotron system, allowing easy and rapid measurement (in less than 3 minutes) of alkaline phosphatase (ALP) activity in capillary blood, venous blood, heparinized plasma or serum. The evaluation of the analytical performance of the assay was carried out at eight clinical laboratories. The study of the imprecision using the measurements in human samples resulted in coefficients of variation ranging from 1.3% to 4.6% (within-run) and from 3.2% to 4.0% (day-to-day). The analytical specificity of the Reflotron ALP assay agrees well with ALP methods using a N-methyl-D-glucamine buffer solution. The calibration of the Reflotron ALP assay, however, is related to the reference intervals for ALP methods using a diethanolamine buffer solution. Method comparisons were performed with the ALP method on Hitachi instruments using diethanolamine buffer. Reflotron ALP measurements in blood and plasma in 157 randomly selected split samples showed excellent agreement (slope: 0.99; intercept: 0.7 U/l; median bias: 2.3%; median difference from the comparison method: -0.3%). Specimens from pregnant women and adolescents were excluded from this study. Differing values were obtained in a method comparison using 48 samples containing predominantly the ALP bone isoform (slope: 0.81; intercept: 31.5 U/l; median bias: 5.7%; median difference from the comparison method: -12.2%). Regression analysis of the results from 21 sera with prevailing placental ALP gave a slope of 1.51, and an intercept of -41.1 U/l (median bias: 8.6%; median difference from the comparison method: 35.6%). Reflotron ALP was compared with three different wet chemistry procedures using different buffer compounds: N-methyl-D-glucamine or diethanolamine or 2-amino-2-methyl-1-propanol. In samples containing predominantly ALP isoforms not of liver origin, the measurements with N-methyl-D-glucamine buffer gave the best fit with respect to Reflotron. In an interference study with 18 drugs, no effect on the test results could be detected. Total bilirubin up to 750 micromol/l and hemolysis up to 1.7 g/l free hemoglobin did not influence the test. Reflotron ALP proved to be an easy and rapid method with excellent precision. The accuracy related to an ALP method using diethanolamine buffer was good. The systematic differences for ALP in samples from pregnant women and adolescents have to be taken into account. The assay is well suited for differential diagnosis of hepatic diseases in decentralized testing.

Alkaline Phosphatase↗
PubMed1961

Isolation of Salmonellae from food samples. IV. Comparison of methods of enrichment.

A comparison of various methods of enhancing frequency of Salmonella isolations revealed that inoculation of a second enrichment broth, with culture from the first, was no improvement over the single direct enrichment method. It was inferior to centrifugation. Selenite was observed to produce more positive isolations at 48 hr than at 24. No change occurred in tetrathionate. Reconstitution of dried albumen with water produced a significant increase in isolations over direct inoculation of enrichment broth in the case of tetrathionate but not selenite broth.Pre-enrichment in lactose broth before inoculation of enrichment media was vastly superior to reconstitution in water for both enrichment broths. A comparison of results obtained using dulcitol, mannitol, lactose and carbohydrate-free purple broths in pre-enrichment indicated that the carbohydrate added was immaterial.

Culture Media↗
PubMed1985

[Evaluation of bacterial growth rate by the ATP-bioluminescence method (luciferase assay)--comparison with conventional methods and application to clinical studies].

Bacterial growth rate was evaluated by estimating the increase in ATP content of cultures of bacterial suspensions using luciferase assay, and the method was applied to the estimation of bactericidal activity of serum and anti-bacterial activity of antibiotics. The results obtained were as follows: The bacterial numbers or bacterial growth rate determined by the ATP-Bioluminescence method was in accordance with those by CFU assay and spectrometrical assay by optical density readings. Furthermore this method was confirmed to be non-time-consuming and more simple than other methods. Using this method, anti-bacterial activity of fresh serum was evaluated. The serum suppressed the growth rate of E. coli, Str. fecalis, CBS, Kleb. pneumoniae and Staph. aureus at least for 2 hours. Heat-inactivated serum and absorbed serum with bacteria tended to lose such suppressive effect. Thus the main effective factors seem to be complements and specific antibody. The anti-microbial activity of antibiotics was enhanced by addition of fresh serum to bacterial cultures, and the results were not in accordance with those by the conventional Disc method. Thus the sensitivity test under the influence of fresh serum is recommended in order to know the clinical effect of antibiotics. These results suggest the usefulness of ATP-Bioluminescence method in the clinical laboratory examinations or investigations.

Adenosine Triphosphate↗