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Results for “method comparison”

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PubMed1996

Enzymatic measurement of creatine in erythrocytes.

We describe an automated enzymatic procedure for quantifying creatine in erythrocytes. In this assay, after sample clean-up, creatine kinase (CK; EC 2.7.3.2) and pyruvate kinase (EC 2.1.7.40) are used as auxiliary enzymes; lactate dehydrogenase (EC 1.1.1.27) is used in the indicator reaction. CK is also used as the starting reagent. Data obtained with the present method (y) correlated as follows with those from the comparison method (x) for creatine measurement in erythrocytes (colorimetric, diacetyl-alpha-naphthol): y = 1.017x - 27.5 (S(y/x) = 11.9, r = 0.997). Precision data were obtained by analyzing three different samples of erythrocytes nine times per day for 25 days with both methods. The total CVs determined by our method and the comparison method were respectively 3.0-4.8% (measured creatine range, 171-463 micromol/L) and 5.1-7.1% (creatine, 185-485 micromol/L). We established the reference interval (mean +/- 2SD) for creatine in erythrocytes from healthy individuals as 194-538 micromol/L for men (n = 71) and 241-677 micromol/L for women (n = 100). Using erythrocytes from patients with various hematological abnormalities and chronic renal failure, who were being treated with continuous ambulatory peritoneal dialysis or hemodialysis, we performed a clinical evaluation and obtained results in agreement with existing data on biochemical markers for the mean age of erythrocytes.

Adolescent↗

PubMed1984

[Structural relations in the comparison of methods in clinical chemistry. Application to the study of bias between a centrifugal analysis (Cobas) and the Kodak-Ektachem method].

In this paper, the authors present the aims of a comparison of 2 biochemical methods in terms of their accuracy. They discuss the inadequacies of classical statistical techniques (paired series, linear correlation coefficient, regression). Instead of them, the authors suggest other approaches based on the structural relationship and, more particularly, York's method which, at the present time, seems to be the best one adapted to the most frequently encountered experimental conditions. They illustrate their view by a study of bias between centrifuge analysis (Cobas) and the Kodak-Ektachem process in plasma calcium assay.

Autoanalysis↗

PubMed1998

Reference standardization and triglyceride interference of a new homogeneous HDL-cholesterol assay compared with a former chemical precipitation assay.

A homogeneous HDL-c assay (HDL-H), which uses polyethylene glycol-modified enzymes and sulfated alpha-cyclodextrin, was assessed for precision, accuracy, and cholesterol and triglyceride interference. In addition, its analytical performance was compared with that of a phosphotungstic acid (PTA)/MgCl2 precipitation method (HDL-P). Within-run CVs were < or = 1.87%; total CVs were < or = 3.08%. Accuracy was evaluated in fresh normotriglyceridemic sera using the Designated Comparison Method (HDL-H = 1.037 Designated Comparison Method + 4 mg/L; n = 63) and in moderately hypertriglyceridemic sera by using the Reference Method (HDL-H = 1.068 Reference Method - 17 mg/L; n = 41). Mean biases were 4.5% and 2.2%, respectively. In hypertriglyceridemic sera (n = 85), HDL-H concentrations were increasingly positively biased with increasing triglyceride concentrations. The method comparison between HDL-H and HDL-P yielded the following equation: HDL-H = 1.037 HDL-P + 15 mg/L; n = 478. We conclude that HDL-H amply meets the 1998 NCEP recommendations for total error; its precision is superior compared with that of HDL-P, and its average bias remains below +/-5% as long as triglyceride concentrations are < or = 10 g/L and in case of moderate hypercholesterolemia.

Chemical Precipitation↗

PubMed1994

A comparison of methods for testing homogeneity of proportions in teratologic studies.

We consider teratologic studies in which the aim is to compare the survival rate of animals in a treatment group to the corresponding rate in a control group. The design of such studies often involves the allocation of intact litters of animals to treatment, invalidating the application of standard statistical methods. We review the strengths and weaknesses of several approaches for dealing with this problem including methodology recently developed for the analysis of clustered binary data. A simulation study is conducted in which litter sizes are generated from a distribution having specified mean and degree of imbalance. It is recommended on the basis of this study and on theoretical considerations that the choice of method should depend on whether the comparison of interest is experimental or observational. For experimental comparisons, involving the random assignment of litters to different treatment groups, methods based on the adjustment of standard chi-square statistics are recommended unless the number of litters in each group is very large.

Animals↗

PubMed1996

Protein structure comparison using representation by line segment sequences.

This paper proposes a new comparison method of tertiary protein structures. The method consists of two parts. First, a sequence of line segments which approximates each tertiary protein structure is computed. Then, an alignment of the sequences of line segments corresponding to input structures is computed. The proposed method is considered as an intermediate one between two comparison methods: a method based on topology diagram and a method based on structure alignment. Moreover it takes less CPU time than structure alignment methods because most structures are represented by means of sequences of at most 100 line segments. The effectiveness of the method is confirmed through a comparison with a previous method and an application to database searching for similar structures.

Algorithms↗

PubMed1979

Bone marrow acid phosphatase in prostate cancer: an assessment by immunoassay and biochemical methods.

Comparisons of the bone marrow and serum acid phosphatase values obtained by counterimmunoelectrophoresis and the Roy biochemical test were made in 72 patients with and in 13 patients without prostatic cancer. The counter-immunoelectrophoresis test, when positive at more than 1 international unit per liter, showed only 4.4% falsely positive results. The Roy biochemical test, which uses sodium thymolphthalein monophosphate as the substrate, had 65% falsely positive bone marrow acid phosphatase levels. Conflicting reports regarding the value of bone marrow acid phosphatase determinations in patients with prostatic cancer result from the use of non-specific substrates in biochemical methods for measurement and from the trauma incidental to bone marrow aspiration, which releases many non-prostatic acid phosphatase enzymes. The use of immunoassay such as counter-immunoelectrophoresis minimizes this source of error.

Acid Phosphatase↗

PubMed1980

Bone marrow acid phosphatase in prostate cancer: an assessment by immunoassay and biochemical methods.

Comparisons of the bone marrow and serum acid phosphatase values obtained by counter-immunelectrophoresis and the Roy biochemical test were made in 72 patients with and in 13 patients without prostatic cancer. The counter-immunoelectophoresis test, when positive at more than 1 international unit per liter, showed only 4.4 per cent falsely positive results. The Roy biochemical test, which used sodium thymolphthalein monophosphate as the substrate, had 65 per cent falsely positive bone marrow acid phosphatase levels. Conflicting reports regarding the value of bone marrow acid phosphatase determinations in patients with prostatic cancer result from the use of non-specific substrates in biochemical methods for measurement and from the trauma incidental to bone marrow aspiration, which releases many non-prostatic acid phosphatase enzymes. The use of immunoassay such as counter-immunoelectrophoresis minimizes this source of error.

Acid Phosphatase↗

PubMed2006

Feasibility of fully automated detection of fiducial markers implanted into the prostate using electronic portal imaging: a comparison of methods.

PURPOSE: To investigate the feasibility of fully automated detection of fiducial markers implanted into the prostate using portal images acquired with an electronic portal imaging device. METHODS AND MATERIALS: We have made a direct comparison of 4 different methods (2 template matching-based methods, a method incorporating attenuation and constellation analyses and a cross correlation method) that have been published in the literature for the automatic detection of fiducial markers. The cross-correlation technique requires a-priory information from the portal images, therefore the technique is not fully automated for the first treatment fraction. Images of 7 patients implanted with gold fiducial markers (8 mm in length and 1 mm in diameter) were acquired before treatment (set-up images) and during treatment (movie images) using 1MU and 15MU per image respectively. Images included: 75 anterior (AP) and 69 lateral (LAT) set-up images and 51 AP and 83 LAT movie images. Using the different methods described in the literature, marker positions were automatically identified. RESULTS: The method based upon cross correlation techniques gave the highest percentage detection success rate of 99% (AP) and 83% (LAT) set-up (1MU) images. The methods gave detection success rates of less than 91% (AP) and 42% (LAT) set-up images. The amount of a-priory information used and how it affects the way the techniques are implemented, is discussed. CONCLUSIONS: Fully automated marker detection in set-up images for the first treatment fraction is unachievable using these methods and that using cross-correlation is the best technique for automatic detection on subsequent radiotherapy treatment fractions.

Feasibility Studies↗

PubMed1991

A brief comparison of methods for preparing fish chromosomes: an overview.

Methods for preparing fish chromosomes are presented for comparison, and their differences and similarities are given in tabular form. Many of the seemingly new and improved methods are merely modifications of known techniques. Differences between the methods used to prepare slides complicate the direct comparison of results. The development of standard methods appears to be desirable.

Animals↗

PubMed1989

Assessment of the significance and severity of premenstrual tension--II. Comparison of methods.

Seven methods for the detection of premenstrual tension (PMT) have been compared, using daily records of bipolar mood scores kept by 44 women with the premenstrual syndrome during 133 menstrual cycles. Four of the methods were simple procedures based on contrasting the premenstrual scores with those elsewhere in the cycle and using either a ratio or difference to detect PMT. In the other three methods, the mood scores were fitted to a model. The comparison suggest that methods which (1) use bipolar scores, (2) optimise the thresholds separating PMT+ from PMT- cycles and (3) are based on known PMT symptom patterns, are likely to be satisfactory whatever their level of sophistication. Methods based on unipolar scores on the other hand, succeed only when PMT severity is measured as the difference between two quantities, and fail when ratios are used. In this study with its bipolar mood score data base, six of the methods gave similar results. Discrepancies between methods (9-23%) were associated with double symptom peaks and with the appearance of symptoms early in the luteal phase. For such cycles only the method based on a 5-term Fourier series provided useful information.

Emotions↗

PubMed1992

Quantitative method for comparison of skeletal muscle architectural properties.

A numerical method is presented which calculates the architectural difference index between two muscles. This index is based upon the parameters, identified using statistical discriminant analysis, which best characterize the various muscles. This index can be used to reduce multiple architectural properties into a single value and may be useful in selecting donor muscles which are required to perform a substitute function for another muscle which has been lost or injured.

Animals↗

PubMed1979

Comparative studies of the primary structures of ribosomal RNAs of several eukaryotic cell lines by the fingerprinting method.

Comparisons of the primary structures of 18S and 28S ribosomal RNAs of man, rat, mouse and chicken were made by two-dimensional fractionation including electrophoresis at pH 3.5 and homochromatography. All large T1 oligonucleotides were recovered from the different fingerprints and their radioactivity was measured. They were then hydrolysed with pancreatic RNase and the pancreatic products were digested with alkali to determine their base composition and detect modified residues. Finally, residues bearing a modification on the ribose were analysed by hydrolyses with snake venom and spleen phosphodiesterases. For the 18A RNAs 23, 27, 26, 24 oligonucleotides, whose lengths range from 22 to 10 residues, were analyzed respectively for man, rat, mouse and chicken. Among these, 14 are identical in the four species, two at least are common to man, rat, mouse but differ by the presence of A-Cps in chicken spot 4' instead of A-Up in spot 4 and A2-Gp in chicken spot 14 instead of A2-Gp in spot 13. For the 28S RNAs of man, rat, mouse and chicken, 20, 19, 21 and 22 oligonucleotides ranging in length from 27 to 12 residues were analyzed. 11 of them are common to the four species; 4 of them are found in man, rat, mouse and one of these (spot 1) has a corresponding spot in chicken from which it differs only by the existence of A3-Up instead of A2-Up. Another mammalian oligonucleotide (spot 6) differs from its homologous chicken spot (spot 6') bytwo point mutations. The same modified residues as found by Khan and Maden in man, chicken, and xenopus, have been found in rat and mouse. Moreover when these modified residues are common to several species they are found within an identical nucleotide sequence, as can be seen in the case of spots 1, 3, 9, 11 of 18S RNAs and 4, 7, 13 for 28S RNAs. The number of differences observed between the ribosomal RNAs of the four species were compared to the number of differences observed in the same species for several proteins, globins alpha and beta, insulin, cytochrome C and lysozyme.

Animals↗

PubMed1996

Histogram-matching and histogram-flattening contrast correction methods: a comparison.

OBJECTIVES: To compare the results or two methods of histogram matching and two methods of histogram flattening for their ability to correct for contrast variations in digital dental images. METHODS: A custom-built, aluminium stepwedge with 0.1, 0.5 and 1.0 mm steps was placed over Ektaspeed films and exposed for 0.06, 0.12 and 0.25 s, respectively. Radiographs were digitized at 50 microns spatial resolution and 12-bit contrast resolution. Contrast corrections were performed using Rüttimann et al.'s algorithm (1986) for one method of matching (RM) and flattening (RF) and Castleman's algorithm (1979) for the other method of matching (CM) and flattening (CF). Mean pixel grey-scale values were determined for each step. The 0.12 s exposure was considered to be the target image exposure. Absolute differences in pixel grey-scale values between the target images and the modified images were determined. RESULTS: The median values of the absolute differences in pixel grey-scale values between the target images and the contrast corrected images were: CM = 4.3; RM = 4.1; CF = 70.2 and RF = 70.2. CONCLUSION: Castleman's and Rüttimann's matching algorithms perform equally well in correcting digital image contrast. Histogram flattening was less effective.

Algorithms↗

PubMed2003

Performance characteristics of four immunonephelometric assays for the quantitative determination of IgA and IgM in cerebrospinal fluid.

Measurement of IgA and IgM in cerebrospinal fluid (CSF) can be useful in the diagnosis of multiple sclerosis and other central nervous system disorders. The Dade Behring (Deerfield, IL) N Latex IgA and N Latex IgM tests on the BN II System and Beckman Coulter (Brea, CA) low-concentration IgA and IgM tests on the IMMAGE Immunochemistry System were evaluated for linearity, imprecision, method comparison, and reference interval verification. Both IgA methods were linear from 1.4 to at least 50 mg/L. Both IgM methods were linear from 0.14 to more than 6 mg/L. The total imprecision of the BN II IgA and IgM methods and the IMMAGE IgA method was less than 10%. The imprecision of the IMMAGE IgM method was 10.2% at 0.49 mg/L and less than 5% at higher IgM concentrations. Method comparison studies indicated that IgA and IgM methods on both instruments showed good comparability. Reference interval studies demonstrated that both methods had similar reference intervals that agreed with published values of less than 6 mg/L for IgA and less than 1.3 mg/L for IgM. Methods for quantifying IgA and IgM in CSF on the BN II and IMMAGE nephelometers perform well and give comparable results.

Humans↗

PubMed1998

"Threshold-level" multipulse transcranial electrical stimulation of motor cortex for intraoperative monitoring of spinal motor tracts: description of method and comparison to somatosensory evoked potential monitoring.

UNLABELLED: Numerous methods have been pursued to evaluate function in central motor pathways during surgery in the anesthetized patient. At this time, no standard has emerged, possibly because each of the methods described to date requires some degree of compromise and/or lacks sensitivity. OBJECT: The goal of this study was to develop and evaluate a protocol for intraoperative monitoring of spinal motor conduction that: 1) is safe; 2) is sensitive and specific to motor pathways; 3) provides immediate feedback; 4) is compatible with anesthesia requirements; 5) allows monitoring of spontaneous and/or nerve root stimulus-evoked electromyography; 6) requires little or no involvement of the surgical team; and 7) requires limited equipment beyond that routinely used for somatosensory evoked potential (SSEP) monitoring. Using a multipulse electrical stimulator designed for transcranial applications, the authors have developed a protocol that they term "threshold-level" multipulse transcranial electrical stimulation (TES). METHODS: Patients considered at high risk for postoperative deficit were studied. After anesthesia had been induced and the patient positioned, but prior to incision, "baseline" measures of SSEPs were obtained as well as the minimum (that is, threshold-level) TES voltage needed to evoke a motor response from each of the muscles being monitored. A brief, high-frequency pulse train (three pulses; 2-msec interpulse interval) was used for TES in all cases. Data (latency and amplitude for SSEP; threshold voltage for TES) were collected at different times throughout the surgical procedure. Postoperative neurological status, as judged by evaluation of sensory and motor status, was compared with intraoperative SSEP and TES findings for determination of the sensitivity and specificity of each electrophysiological monitoring technique. Of the 34 patients enrolled, 32 demonstrated TES-evoked responses in muscles innervated at levels caudal to the lesion when examined after anesthesia induction and positioning but prior to incision (that is, baseline). In contrast, baseline SSEPs could be resolved in only 25 of the 34 patients. During surgery, significant changes in SSEP waveforms were noted in 12 of these 25 patients, and 10 patients demonstrated changes in TES thresholds. Fifteen patients experienced varying degrees and durations of postoperative neurological deficit. Intraoperative changes in TES thresholds accurately predicted each instance of postoperative motor weakness without error, but failed to predict four instances of postoperative sensory deficit. Intraoperative SSEP monitoring was not 100% accurate in predicting postoperative sensory status and failed to predict five instances of postoperative motor deficit. As a result of intraoperative TES findings, the surgical plan was altered or otherwise influenced in six patients (roughly 15% of the sample population), possibly limiting the extent of postoperative motor deficit experienced by these patients. CONCLUSIONS: This novel method for intraoperative monitoring of spinal motor conduction appears to meet all of the goals outlined above. Although the risk of postoperative motor deficit is relatively low for the majority of spine surgeries (for example, a simple disc), high-risk procedures, such as tumor resection, correction of vascular abnormalities, and correction of major deformities, should benefit from the virtually immediate and accurate knowledge of spinal motor conduction provided by this new monitoring approach.

Adolescent↗

PubMed1990

Growth related increase in rat intervertebral disc size: a quantitative radiographic and histologic comparison.

Methods were developed for measuring the width of lumbar intervertebral discs in Sprague-Dawley rats. Rates of growth of the L4-5 and L5-6 discs in a rostral-caudal direction in an approximately midsagittal plane were reported from analysis of radiographic and histologic data. The radiographic data correlated with histologic data (p less than 0.001). It was concluded that the L4-5 and L5-6 intervertebral discs continue to increase in size throughout the first 18 months of life of the rat, well past the age of rapid gain in body weight.

Animals↗

PubMedDate not supplied

[Structural analysis of translating ribosomes. Proton magnetic resonance method].

Comparison has been made of the proton magnetic resonance (PMR) spectra of translating ribosomes in the pre-translocation and post-translocation states as well as of the complexes of translating ribosomes with elongation factors Tu (EF-Tu) or G (EF-G) in the presence of the uncleavable analogue of GTP--guanylyl-imidodiphosphate (GMP-PNP). It is shown that proteins L7/L12 within the translating ribosomes possess a high intramolecular mobility both in the pre-translocation and in the post-translocation states. The interaction of EF-G with translating ribosomes results in a decrease of the mobility of the L7/L12 proteins. The interaction of EF-Tu with translating ribosomes leads to slight changes in the PMR spectra different from the changes caused by EF-G.

Magnetic Resonance Spectroscopy↗

PubMed1981

[Diagnosis of cardiac insufficiency in patients with acute myocardial infarct by non-invasive methods].

Comparison of the clinical noninvasive findings with wedge pressure allowed the authors to disclose the most informative signs for the recognition of normal or abnormal pressure in the pulmonary capillaries. The use of the successive diagnostic procedure provides the possibility for correct recognition of normal or increased wedge pressure in 76% of cases and of pressure within the range of compensatory values and exceeding them, in 77.5%.

Acute Disease↗