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PubMed2005

Comparison of nonlinear dynamic methods and perturbation methods for voice analysis.

Nonlinear dynamic methods and perturbation methods are compared in terms of the effects of signal length, sampling rate, and noise. Results of theoretical and experimental studies quantitatively show that measurements representing frequency and amplitude perturbations are not applicable to chaotic signals because of difficulties in pitch tracking and sensitivity to initial state differences. Perturbation analyses are only reliable when applied to nearly periodic voice samples of sufficiently long signal lengths that were obtained at high sampling rates and low noise levels. In contrast, nonlinear dynamic methods, such as correlation dimension, allow the quantification of chaotic time series. Additionally, the correlation dimension method presents a more stable analysis of nearly periodic voice samples for shorter signal lengths, lower sampling rates, and higher noise levels. The correlation dimension method avoids some of the methodological issues associated with perturbation methods, and may potentially improve the ability for real time analysis as well as reduce costs in experimental designs for objectively assessing voice disorders.

Adult↗
PubMed1987

Comparative analysis of two rapid automated methods and a semiautomated version of the urease method for determining aminoglycoside concentrations in serum.

The Syva EMIT Autolab 6000 and the Abbott TDX automated methods for measuring serum aminoglycoside concentrations were compared with each other and with a new semiautomated version of the urease technique. Each was evaluated for accuracy, reproducibility, cost, and ease of use. All three methods gave satisfactory results, although the Abbott TDX was the most accurate. Both automated methods gave results within minutes, whereas the new urease method, which involved more initial manipulation, took 1.25 h to complete (mainly incubation time). There was no difference in accuracy of performance between experienced and inexperienced operators. The new urease method was much cheaper in terms of initial capital expenditure and in cost per test and needed no provision of manufacturer's back-up maintenance services. This could prove invaluable in situations where financial resources are at a premium. Otherwise, the Abbott TDX is currently our method of choice, and reasons for its preference to the EMIT system are listed.

Anti-Bacterial Agents↗
PubMed2025

A universal, high-quality, and high-yield DNA purification method for mycobacteria, including Mycobacterium tuberculosis: large-scale assessment of the chloroform-bead method.

UNLABELLED: Genomic analysis of mycobacteria has become increasingly crucial for understanding drug-resistance mechanisms, molecular epidemiology, and pathogenesis. However, efficient extraction of high-molecular-weight genomic DNA from these organisms remains challenging because of their thick mycolic acid-rich cell walls. In this study, we report the chloroform-bead method, a universal DNA extraction protocol that combines chemical and mechanical disruptions to overcome these challenges. Multi-laboratory evaluation (16 sites) demonstrated the chloroform-bead method's superiority over conventional methods for Mycobacterium tuberculosis (DNA yield: 17.9 vs 1.9 &#xb5;g, purity A260/A230: 1.86 vs 1.22, both P < 0.001). Single-facility assessment extended these findings to >32 nontuberculous mycobacterial species (n = 1,058), showing performance comparable to M. tuberculosis (n = 1,000), with both achieving median yields of 22.2 &#xb5;g DNA and consistent quality metrics. The chloroform-bead method significantly reduced the processing time from 2 to 3 days to 2 h while ensuring complete sample sterilization, eliminating the need for species-specific optimization. This streamlined and universally applicable protocol represents a practical advancement in mycobacterial DNA extraction methodology, ideal for high-throughput genomic studies and routine clinical diagnostics. IMPORTANCE: Mycobacterial genomics is crucial for understanding pathogenesis and drug resistance; however, DNA extraction remains a significant challenge because of its unique cell wall. Traditional methods rely on enzymatic treatments, resulting in complex and time-consuming protocols with variable results. The chloroform-bead method introduces a paradigm shift by chemically and mechanically disrupting the mycolic acid layer and eliminating the need for enzymatic treatment. This standardized approach ensures consistent, high-quality DNA extraction across diverse mycobacterial species, thereby enhancing research capabilities and clinical applications.

Chloroform↗
PubMed1975

The acetyltransferase enzyme method for the assay of serum gentamicon concentrations and a comparison with other methods.

The adenylytransferase/acetyltransferase methods of gentamicin assay have been evaluated for accuracy, speed, and cost. For a comparable cost of materials the latter method is more accurate than that using the adenylytransferase enzyme. The acetyltransferase method is much quicker than the adenyltransferase due to the shorter time necessary for radioactive counting. Sonication is an easier method of enzyme preparation than the previously used osmotic shock technique. The acetyltransferase method is reproducible and there was a very good correlation between it and a microbiological agar-plate diffusion method.

Acetyltransferases↗
PubMed1979

Superiority of a soil debris isolation method over a beet seed colonization method for assay of Rhizoctonia solani at high soil inoculum densities.

A quantitative soil debris isolation method (all debris from known weight of soil plated) and a garden beet seed saprophytic colonization method were compared over a 1-year period for assaying Rhizoctonia solani population. Four fields of different soil textures were selected. Within each field four areas of healthy and four areas of diseases (rhizoctonia root and crown rot) sugarbeets were sampled bimonthly from August 1976 until June 1977. The maximum numbers of R. solani colonies obtained by the debris method were 2 per gram of soil in areas of healthy beets, and 11 per gram of soil in areas of diseased sugarbeets. At such high inoculum densities the beet seed colonization method underestimated R. solani populations, because the inoculum per unit of soil exceeded the numbers of beet seeds per unit of soil available for colonization. Modifications of the beet seed method did not significantly alter results of colonization assays. Ranked correlation comparisons of assay methods yielded r = 0.81 for all data.

Mitosporic Fungi↗
PubMed2006

Spatial four-alternative forced-choice method is the preferred psychophysical method for naïve observers.

H. R. Blackwell (1952) investigated the influence of different psychophysical methods and procedures on detection thresholds. He found that the temporal two-interval forced-choice method (2-IFC) combined with feedback, blocked constant stimulus presentation with few different stimulus intensities, and highly trained observers resulted in the "best" threshold estimates. This recommendation is in current practice in many psychophysical laboratories and has entered the psychophysicists' "folk wisdom" of how to run proper psychophysical experiments. However, Blackwell's recommendations explicitly require experienced observers, whereas many psychophysical studies, particularly with children or within a clinical setting, are performed with naïve observers. In a series of psychophysical experiments, we find a striking and consistent discrepancy between naïve observers' behavior and that reported for experienced observers by Blackwell: Naïve observers show the "best" threshold estimates for the spatial four-alternative forced-choice method (4-AFC) and the worst for the commonly employed temporal 2-IFC. We repeated our study with a highly experienced psychophysical observer, and he replicated Blackwell's findings exactly, thus suggesting that it is indeed the difference in psychophysical experience that causes the discrepancy between our findings and those of Blackwell. In addition, we explore the efficiency of different methods and show 4-AFC to be more than 3.5 times more efficient than 2-IFC under realistic conditions. While we have found that 4-AFC consistently gives lower thresholds than 2-IFC in detection tasks, we have found the opposite for discrimination tasks. This discrepancy suggests that there are large extrasensory influences on thresholds--sensory memory for IFC methods and spatial attention for spatial forced-choice methods--that are critical but, alas, not part of theoretical approaches to psychophysics such as signal detection theory.

Attention↗
PubMed1985

Methods of assigning accurate values to reference serum. Part 2. The use of definitive methods, reference laboratories, transferred values and consensus values.

Eight analytes (Ca, Cl, cholesterol, glucose, Mg, K, Na and urate) have been determined in one horse serum masterlot by up to six different procedures: (i) by so-called definitive methods; (ii) by a group of reference laboratories using a variety of analytical methods; (iii) using the results of two independent external quality assessment schemes; (iv) by transferring values from a human serum standard reference material analysed by definitive methods; (v) by similar transfer of values from several batches of horse reference serum previously analysed by definitive methods; and (vi) as in (v) but using a group of reference laboratories. The results have confirmed the validity and usefulness of the transfer process in value assignment and in identifying outliers due to inaccurate methods. Definitive methods are shown to be subject to error, and although they appear to be the most accurate single techniques currently available, they are not definitive in the sense of being without bias and having no known source of inaccuracy.

Animals↗
PubMed2003

Biostatistical methods for the validation of alternative methods for in vitro toxicity testing.

Statistical methods for the validation of toxicological in vitro test assays are developed and applied. Validation is performed either in comparison with in vivo assays or in comparison with other in vitro assays of established validity. Biostatistical methods are presented which are of potential use and benefit for the validation of alternative methods for the risk assessment of chemicals, providing at least an equivalent level of protection through in vitro toxicity testing to that obtained through the use of current in vivo methods. Characteristic indices are developed and determined. Qualitative outcomes are characterised by the rates of false-positive and false-negative predictions, sensitivity and specificity, and predictive values. Quantitative outcomes are characterised by regression coefficients derived from predictive models. The receiver operating characteristics (ROC) technique, applicable when a continuum of cut-off values is considered, is discussed in detail, in relation to its use for statistical modelling and statistical inference. The methods presented are examined for their use for the proof of safety and for toxicity detection and testing. We emphasise that the final validation of toxicity testing is human toxicity, and that the in vivo test itself is only a predictor with an inherent uncertainty. Therefore, the validation of the in vitro test has to account for the vagueness and uncertainty of the "gold standard" in vivo test. We address model selection and model validation, and a four-step scheme is proposed for the conduct of validation studies. Gaps and research needs are formulated to improve the validation of alternative methods for in vitro toxicity testing.

Animal Testing Alternatives↗
PubMed2002

Comparison of an aggregate scoring method with a consensus scoring method in a measure of clinical reasoning capacity.

BACKGROUND: Diversity of clinical reasoning paths of thought among experts is well known. Nevertheless, in written clinical reasoning assessment, the common practice is to ask experts to reach a consensus on each item and to assess students on a unique "good answer." PURPOSES: To explore the effects of taking the variability of experts answers into account in a method of clinical reasoning assessment based on authentic tasks: the Script Concordance Test. METHODS: Two different methods were used to build answer keys. The first incorporated variability among a group of experts (criterion experts) through an aggregate scoring method. The second was made with the consensus obtained from the group of criterion experts for each answer. Scores obtained with the two methods by students and another group of experts (tested experts) were compared. The domain of assessment was gynecology-obstetric clinical knowledge. The sample consisted of 150 clerkship students and seven other experts (tested experts). RESULTS: In a context of authentic tasks, experts' answers on items varied substantially. Amazingly, 59% of answers given individually by criterion group experts differed from the answer they provided when they were asked in a group to provide the "good answer" required from students. The aggregate scoring method showed several advantages and was more sensitive to detecting expertise. CONCLUSIONS: The findings suggest that, in assessment of complex performance in ill-defined situations, the usual practice of asking experts to reach a consensus on each item reduces and hinders the detection of expertise. If these results are confirmed by other researches, this practice should be reconsidered.

Cluster Analysis↗
PubMed2003

Comparison of the auxiliary function method and the discrete-ordinate method for solving the radiative transfer equation for light scattering.

Two methods for solving the radiative transfer equation are compared with the aim of computing the angular distribution of the light scattered by a heterogeneous scattering medium composed of a single flat layer or a multilayer. The first method [auxiliary function method (AFM)], recently developed, uses an auxiliary function and leads to an exact solution; the second [discrete-ordinate method (DOM)] is based on the channel concept and needs an angular discretization. The comparison is applied to two different media presenting two typical and extreme scattering behaviors: Rayleigh and Mie scattering with smooth or very anisotropic phase functions, respectively. A very good agreement between the predictions of the two methods is observed in both cases. The larger the number of channels used in the DOM, the better the agreement. The principal advantages and limitations of each method are also listed.

Journal Article↗
PubMed1989

Comparison of the reflectance method (Reflotron reflectance photometer) with the absorbance method (automatic analysers) for the determination of cholesterol.

The European Atherosclerosis Society (1) and the Expert Panel of the US National Cholesterol Education Program (2) have issued detailed guide values for recognition and management of hyperlipidaemia in adults. In these guidelines, the diagnosis of dyslipidaemia based on the measurements of total cholesterol, triacylglycerols, HDL and LDL cholesterol plays an important role. A prerequisite for the desired success of interventive measures is the reliability of the analytical data. The aim of this study was to investigate the precision and accuracy of Reflotron Cholesterol, a method based on the dry chemistry principle. Accuracy was assessed by establishing the correlation with the standardized automated methods used in routine lipid diagnosis. In addition, it was also examined whether the Reflotron Cholesterol results in plasma and blood are comparable. The Reflotron cholesterol (sample: blood) showed a good correlation with the CHOD/PAP method on a Hitachi 737 instrument (sample: plasma). The median value of the differences of the test results was -0.4%. Similarly, the method comparison of Reflotron Cholesterol (sample: blood) versus CHOD/PAP method on a SMAC instrument (sample: plasma) showed that Reflotron produces slightly (1.8%) higher results. The Reflotron Cholesterol values obtained from blood samples were slightly lower than those from plasma samples (median value of the differences: -2.2%). The results suggest that for routine purposes Reflotron Cholesterol provides results which are in good agreement with those obtained by standardized wet chemistry methods.

Autoanalysis↗
PubMed1995

Performance of a direct, immunoseparation based LDL-cholesterol method compared to Friedewald calculation and a polyvinyl sulphate precipitation method.

The analytical performance of a direct, immunoseparation based LDL-cholesterol method (Genzyme Corporation) was evaluated on an ELAN analyser (Merck), and compared with the performance of routinely used methods (LDL-cholesterol estimated by the Friedewald equation, and LDL-cholesterol obtained after polyvinyl sulphate precipitation). Within-day coefficients of variation (CVs) were 0.79 to 2.51% for immunoseparation based LDL-cholesterol; the between-day CVs varied between 2.62 and 3.89%, i.e. within the recommended National Cholesterol Education Program (NCEP) goal of < 4%. A method comparison study, according to the National Committee for Clinical Laboratory Standards (NCCLS) EP9-P guidelines, was performed using fasting normo- and hypertriacylglycerolaemic as well as cholestatic sera. In fresh normotriacylglycerolaemic sera immunoseparation based LDL-cholesterol (y) and Friedewald LDL-cholesterol (x) values were identical as slope and intercept of the Passing & Bablok regression equation were not significantly different from one and zero, respectively (y = 1.006 x -0.107; N = 45). In contrast, immunoseparation based LDL-cholesterol (y) differed significantly from polyvinyl sulphate LDL-cholesterol (x) results (y = 0.922 x + 0.234; N = 103). Freezing normotriacylglycerolaemic sera (three weeks, -20 degrees C) resulted in a negative bias of -5.8% for the immunoseparation based LDL-cholesterol method, and in a positive bias of +5.3% for the polyvinyl sulphate method, compared to fresh specimens. Immunoseparated LDL-cholesterol was completely recovered up to at least 37.84 mmol/l serum triacylglycerols. We conclude that the immunoseparation based LDL-cholesterol method is a practical, not technically demanding technique well applicable within routine clinical laboratories.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

Measurement of intrahepatic shunted blood flow by ethanol-1-14C method as compared with D-galactose-1-14C method.

Ethanol-1-14C method for the measurement of intrahepatic shunted blood flow was compared with the method of continuous infusion of D-galactose-1-14C. In controls, in chronic hepatitis, and in hepatic cirrhosis, per cent intrahepatic shunt measured by the ethanol-1-14C- method was about a half or one-third of that measured by the D-galactose-1-14C method. Study of radioactivity-dye concentration ratio of the blood sampled from the inferior vena cava showed that per cent intrahepatic shunt was underestimated by the ethanol-1-14C method because of permeability of ethanol-1-14C through the capillaries. In patients with hepatic carcinoma, in whom the carcinomatous tissue was supplied mainly by the hepatic artery, there was no significant difference in per cent intrahepatic shunt between both methods.

Ethanol↗
PubMed1996

Comparison of measured nutrients with the values calculated by the weighing method and duplicate method.

The values obtained by the weighing and duplicate methods were compared with those obtained by direct chemical measurement to evaluate the validity of these methods on 27 meals in an agricultural village in Aomori Prefecture. Using the Fourth revised edition of the Japanese Standard Food Consumption Table, the lipid, protein, carbohydrate and energy content of each meal were calculated by each method, and the values were compared with the direct, chemically-measured values. The values for nutrients except protein obtained by the weighing method were slightly lower than those obtained by the duplicate method or direct measurement. A higher correlation with the directly-measured values was noted for the values obtained by the duplicate method. Among analyzed nutrient values, the highest correlation was noted for protein, followed by energy.

Aged↗
PubMed2006

Evaluation of a kinetic uricase method for serum uric acid assay by predicting background absorbance of uricase reaction solution with an integrated method.

A patented kinetic uricase method was evaluated for serum uric acid assay. Initial absorbance of the reaction mixture before uricase action (A(0)) was obtained by correcting the absorbance at 293 nm measured before the addition of uricase solution, and background absorbance (A(b)) was predicted by an integrated method. Uric acid concentration in reaction solution was calculated from A, the difference between A(0) and A(b), using the absorptivity preset for uric acid. This kinetic uricase method exhibited CV<4.3% and recovery of 100%. Lipids, bilirubin, hemoglobin, ascorbic acid, reduced glutathione and xanthine <0.32 mmol/L in serum had no significant effects. A linearly responded to 1.2 to 37.5 micromol/L uric acid in reaction solution containing 15 microl serum. The slope of linear response was consistent with the absorptivity preset for uric acid while the intercept was consistent with that for serum alone. Uric acid concentrations in clinic sera by different uricase methods positively correlated to each other. By Bland-Altman analysis, this kinetic uricase method accorded with that by quantifying the total change of UV absorbance on the completion of uricase reaction. These results demonstrated that this kinetic uricase method is reliable for serum uric acid assay with enhanced resistance to both xanthine and other common errors, wider range of linear response and much lower cost.

Humans↗
PubMed1983

Modulation of optical density by sulfhydryl reagents in microbiuret method: a modified method for protein determination in the presence of sulfhydryl reagents.

2-Mercaptoethanol increases the optical density of assay solutions at wavelengths between 280 to 400 nm, and therefore interferes with the measurement of protein concentration by the microbiuret method. Protein concentration can be determined in the presence of 2-mercaptoethanol up to 6 mM by modification of the method as follows: after the precipitation of protein by trichloroacetic acid in the presence of deoxycholate, the precipitate is resolubilized with NaOH solution. Dithiothreitol interfered with the protein determinations could by made in the presence of 4 mM of dithiothreitol with the modified microbiuret method. This modified method is time-saving and more reliable than other methods for protein determination, such as Lowry's method, in the presence of sulfhydryl reagents.

Proteins↗
PubMed1995

Detecting erythromycin resistance in Streptococcus pyogenes: reliability of the disk diffusion method and the breakpoint susceptibility testing method. Finnish Study Group for Antimicrobial Resistance (FIRE).

Erythromycin susceptibility of clinical Streptococcus pyogenes isolates was determined at 19 Finnish clinical microbiology laboratories by their routine disk diffusion method and by a screening method adapted from the breakpoint susceptibility testing method. Results obtained at 12 laboratories using 4 major variants of the disk method were further evaluated. From these laboratories, 286 consecutive resistant and 349 consecutive susceptible isolates were sent to the Antimicrobial Research Laboratory, Turku where the MIC of erythromycin was determined. 96% and 97% of the disk results were correct, as compared with MIC results, when general and laboratory-specific breakpoints, respectively, were used. The results of the screening method were comparable to those of the disk method.

Drug Resistance, Microbial↗
PubMed1993

Search for new and improved radiolabeling methods for monoclonal antibodies. A review of different methods.

The radiolabeling of monoclonal antibodies for routine clinical applications have been intensively researched during the past decade. The traditional radiolabeling methods are direct radioiodination using oxidative reagents, such as chloramine T, and coupling metals by use of bifunctional chelates like diethylenetriamine-pentaacetic acid (DTPA). More recently technetium labeling has also been used. In this review the selection of different radioisotopes is discussed as well as the various traditional or newer methods to introduce the radiolabel into the antibody structure. Labeling methods for radiohalogens, for technetium and rhenium isotopes, and for 3-valent cation radiometals are reviewed. Some of the newer methods offer simplified labeling procedures, but usually the new methods are more complicated than the earlier ones. However, new labeling methods are available for almost any radioelement group and they may result in better preserved original nature of the antibody and lead to better clinical results.

Animals↗