Determination of finger-motion impairment by linear measurement. Description of method and comparison with angular measurement.
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Biomechanical Phenomena↗
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Results for “method comparison”
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Quantitation of metabolites in human skeletal muscle during rest and exercise: a comparison of methods.
Quantitation of muscle metabolites in vastus lateralis needle biopsies from human subjects at rest and following exercise is evaluated using three different methods of normalization of the data, i.e., total protein, total creatine, and NAD+. Coefficients of variation between patient analyses are similar when the metabolite data are normalized by any of the descriptors in resting muscle and in muscle samples obtained following vigorous exercise. When multiple samples are taken from individual patients the intrapatient coefficient of variation is less than that for interpatient comparisons. Normalization to total creatine or NAD+ yields significantly smaller coefficients of variation than does normalization to total protein in these intrapatient comparisons (P less than 0.05). Based on these comparisons, we conclude that any of these methods evaluated for normalizing metabolite content is adequate for studying human subjects, but the total creatine and NAD+ methods may offer some advantage because of the lower variability obtained with these analyses.
Creatine↗
A method of comparison for standardized rates of low-incidence events.
The authors present an approximate but simple approach to comparing age-gender standardized rates of low-incidence events (mortality or morbidity) rates across several geographic areas. The presented method will be useful particularly when a person-level database, one that includes unique person identifiers, is not available. We specify conditions under which comparisons can be made without calculating empirical standard errors and worrying unduly about recurrent events. To compare indirectly standardized rates, only information on the size, the crude rate, and the standardized rate of the areas are needed. For comparing directly standardized rates, which requires stratum-specific rates, the method also requires stratum-specific total numbers of events and individuals but does not require person-level information. The proposed approach builds on previous work comparing rates using person-level data.
Coronary Angiography↗
A critical comparison of methods for the determination of the aging sensitivity in biomedical grade yttria-stabilized zirconia.
Since the recent failure events of two particular series of zirconia femoral heads for total hip replacement prosthesis, a large decrease in the use of zirconia ceramics for orthopaedic implants has been observed. In spite of the biomedical success of this material during the last 10 years, this decrease in use was required for safety reasons, until the cause of the failures is known. It has been shown that these failures were related to the low temperature hydrothermal degradation (also known as aging). Thus, it is crucial to better understand the aging behavior, in order to be able to assess its importance and then control it if required. In this study, various techniques relevant to assess the hydrothermal degradation sensitivity of biomedical grade yttria-stabilized zirconia are discussed and compared. The expected outputs of conventional methods, that is, X-ray diffraction and scanning electron microscopy are examined. More recent methods like optical interferometry and atomic force microscopy are presented, with their respective benefits and drawbacks. An up-to-date comparison of these different techniques is provided, and their use for ensuring the long-term reliability of a particular batch of zirconia in terms of aging degradation is demonstrated.
Biodegradation, Environmental↗
Volume estimates by imaging methods: model comparisons with visible woman as the reference.
OBJECTIVE: To compare the accuracy of four volume estimation models to actual tissue and organ volumes measured in the visible woman. METHODS: Actual volumes were calculated from 1-mm-thick visible woman images that were segmented for five major components including subcutaneous and visceral adipose tissue across the 1730 available slices. Four available models resolved to two equations: truncated cone/truncated pyramid vs. two-column/parallel trapezium. Between-slice interval and initial slice were systematically varied when deriving component volumes using the two equations in four regions. RESULTS: For each compartment and each between-slice interval, the means of the two-column model were always the same as the corresponding reference volumes, whereas those of the truncated cone model were smaller than the reference volumes. Similarly, the coefficient variation for the two-column model was always smaller than for the truncated cone model. DISCUSSION: The equation based on the parallel trapezium and the two-column models is more accurate in estimating tissue volumes than the corresponding equation for truncated pyramid and truncated cone models. This finding has important implications for the volume calculations of imaging-based body compartments such as adipose tissue.
Anatomy↗
A comparison of methods for determining total body protein.
The aim of the study was to find the optimal method (with respect to convenience and accuracy) for determining total protein in whole-body homogenates of rats. Three different protein extraction methods and five different protein concentration methods were assessed. The results were compared against a reference value measured by complete amino acid analysis after acid hydrolysis. The data demonstrated that extraction with 5% (w/v) sodium dodecylsulfate (SDS) in 0.5 N NaOH was far superior to that with water alone or to 6 N guanidine-HCl. A comparison of the Biuret, Bradford, and bicinchoninic acid methods on the SDS-NaOH-extracted samples showed that the Biuret method was optimal, giving a value that was 90% of the reference value with a small variation (2.4% of the mean). The Kjeldahl method gave the correct protein concentration only when a nitrogen factor of 5.51 +/- 0.03 (N = 5) was applied. The results suggest that extraction with SDS-NaOH followed by the Biuret procedure is a good method for measuring protein concentrations in whole body rat homogenates.
Amino Acids↗
Clinical performance of the new cardiac markers troponin T and CK-MB on the Elecsys 2010. A multicentre evaluation.
Elecsys assays for the cardiac markers Troponin T (cTnT) and CK-MB have been evaluated in an international multicenter study on the random access analyzer Elecsys 2010 to characterize their clinical performance and their comparability with respective established routine methods. In method comparison studies of Elecsys Troponin T (TnT) with Enzymun-Test TnT, good correlations (r > or = 0.95) and a high degree of correspondence (slopes in 4 laboratories between 0.95 and 1.05) were found. The method comparison studies of Elecsys CK-MB with various CK-MB routine methods lead to good correlations but some systematic deviation in the slopes due to varying standardization. In a reference population of 350 persons upper reference limits (97.5th percentile) of 0.03 milligrams/l for Elecsys TnT and 3.1 milligrams/l for Elecsys CK-MB were found. In cardiosensitivity studies the equivalent diagnostic information of the new Elecsys assays to routine methods was confirmed in the early diagnosis of acute myocardial infarction (AMI), the detection of minor myocardial damages in patients with unstable angina pectoris (UAP) and in time course data monitoring of AMI and bypass surgery patients. The superior sensitivity of cTnT versus CK-MB has been established in a screening situation where in 29 patients with cardiac diseases only cTnT, but not CK-MB, was found pathologically increased; this was due either to the larger diagnostic window of cTnT in AMI or to the more sensitive recognition of minor myocardial damage. In the same study, the cardiospecificity of Elecsys TnT was found to be at least 99.5%. This has also been demonstrated in an earlier study for Enzymun-Test TnT. Further cardiospecificity testing, e.g. in renal failure patients, showed results equivalent to those of Enzymun-Test TnT. An extended clinical study involving 294 patients with chest pain, of whom 58 had a final diagnosis of AMI, revealed highly comparable sensitivity and specificity for the Elecsys assays and routine methods. Thus, the already recommended clinical cut-off values of 0.1 milligrams/l for cTnT and 5 milligrams/l for CK-MB are also valid for the Elecsys assays. The slightly improved sensitivity of Elecsys TnT in the lower range even allows the recognition of pathological increase at cTnT concentrations below 0.1 milligrams/l in special situations with sufficient additional clinical information. Summarizing, provide the two cardiac markers on the Elecsys 2010 at least equivalent or even superior diagnostic information in various clinical situations of cardiac disease compared with routine methods. The short turn-around time and reliable performance qualify the Elecsys assays as new methods of choice for routine and emergency use.
Adult↗
Production of leptin in Escherichia coli: a comparison of methods.
A procedure is described for gram-scale refolding of Escherichia coli-derived human leptin inclusion bodies. Refolding was achieved by gradually reducing denaturant using a diafiltration method. Refolded leptin is characterized by in vivo modulation of food intake, reduction in body weight, and lowering of insulin and glucose levels in ob/ob mice. In addition, refolded leptin is characterized by radioimmunoassay (RIA) and activation of the leptin receptor in a cell-based assay. For comparison we also refolded leptin by a simple dilution method and produced periplasmic derived leptin, which did not require ex vivo folding. Leptin produced by these three methods and leptin obtained from commercial sources were compared using the RIA and the cell-based assay and appeared to be of comparable quality and potency.
Animals↗
Assay of follitropin and lutropin by fluorescence enzyme immunoassay.
Recently developed fluorescent enzyme immunoassays (FEIs) for follitropin (FSH) and lutropin (LH) designed for the Stratus analyzer were compared with a typical dual FSH-LH radioimmunoassay (RIA) procedure. The FEIs use monoclonal antibodies in a sandwich reaction scheme similar to that of immunoradiometric procedures but with filter paper tabs rather than polystyrene beads and alkaline phosphatase as a tag instead of a radioisotope. Precision of the FEI was comparable with that of the RIA tests with CVs typically under 10%. The detection limit of the FSH test is 0.4 IU/L and that of the LH test is 0.6 IU/L. Measurable carryover exists but is clinically inconsequential. Neither assay exhibits total specificity, but the degree of cross-reactivity is unlikely to be problematic in most situations. Recovery with the FSH assay was 103%, with the LH assay, it averaged 108%. Moderate amounts of bilirubin and triglycerides and gross hemolysis caused no significant interferences. Method comparison studies yielded the following: FEI for FSH, 1.16 RIA + 3.1, r = 0.97, n = 114; FEI for LH, 0.77 RIA - 0.23, r = 0.96, n = 112. Difference analysis of the method comparison data revealed relatively poor agreement between the FEI tests and the dual RIA procedure. With the adoption of method-specific normal reference ranges, the FEI tests offer attractive alternatives to radioisotopic FSH and LH assays.
Cross Reactions↗
HLA-B27 determination using serological methods. A comparison of enzyme immunoassay and a microlymphocytotoxic test with flow cytometry and a molecular biological assay.
Typing for HLA-B27 is routinely performed in patients with seronegative spondarthritides. Besides the microlymphocytotoxic test (MLCT), other serological techniques have been developed such as enzyme immunoassays (EIA) using serum or plasma as a source for the determination of soluble HLA-B27 (sHLA-B27) and flow cytometric (FC) methods. The aim of the present study was to check the accuracy and reliability of the EIA for sHLA-B27 in comparison to the MLCT using antibodies against HLA-B27 and cross-reacting specificities (CRS), as well as an FC method and a molecular biological method. Any discrepant results should be typed with the MLCT using a complete panel of anti-HLA-class I antibodies, with FC and with a molecular biological technique. The EIA should also be repeated in those patients, using serum and plasma from a new venipuncture. In 81 patients with rheumatic disorders, the EIA and the MLCT using antibodies against HLA-B27 and CRS were performed. Based on the MLCT with a complete panel of anti-HLA-class I antibodies as a standard, discrepant test results were obtained for 9 out of 81 patients with the MLCT using antibodies against HLA-B27 and CRS and with the EIA. The following wrong results occurred: in the MLCT with anti-HLA-B27 and CRS, there were two false-negative results; in the EIA there were four false-negative and one false-positive results; one sample was undeterminable. In comparison with the MLCT, including the complete panel of HLA-class I antibodies, as well as with a molecular biological technique, typing with FC showed a complete concordance. Our investigations demonstrated that for routine typing for HLA-B27 the MLCT cannot be replaced by EIA because of a significant number of mistypings. The MLCT performed only with antibodies against HLA-B27 and CRS may also lead to typing errors. No errors were detected using flow cytometry. If only serological methods can be performed in a laboratory a combination of flow cytometry and MLCT could therefore enhance the safety of HLA-B27 typing.
Adult↗
Simultaneous measurements of cerebral blood flow by the xenon/CT method and the microsphere method. A comparison.
Simultaneous measurements of cerebral blood flow have been performed in baboons to assess the correlation between the acute and invasive nondiffusible microsphere technique and the noninvasive xenon-enhanced CT method. Blood flows in small tissue volumes (approximately 1 cm3) were directly compared. The results of these studies demonstrate a statistically significant association between the two methods (P less than .001). Similar correlations were obtained by both the Kendall tau (tau) and the Spearman (r) methods. The problems and limitations of such correlations are discussed.
Animals↗
Is the Framingham risk function valid for northern European populations? A comparison of methods for estimating absolute coronary risk in high risk men.
OBJECTIVE: To examine the validity of estimates of coronary heart disease (CHD) risk by the Framingham risk function, for European populations. DESIGN: Comparison of CHD risk estimates for individuals derived from the Framingham, prospective cardiovascular Münster (PROCAM), Dundee, and British regional heart (BRHS) risk functions. SETTING: Sheffield Hypertension Clinic. Patients-206 consecutive hypertensive men aged 35-75 years without preexisting vascular disease. RESULTS: There was close agreement among the Framingham, PROCAM, and Dundee risk functions for average CHD risk. For individuals the best correlation was between Framingham and PROCAM, both of which use high density lipoprotein (HDL) cholesterol. When Framingham was used to target a CHD event rate > 3% per year, it identified men with mean CHD risk by PROCAM of 4.6% per year and all had CHD event risks > 1.5% per year. Men at lower risk by Framingham had a mean CHD risk by PROCAM of 1.5% per year, with 16% having a CHD event risk > 3.0% per year. BRHS risk function estimates of CHD risk were fourfold lower than those for the other three risk functions, but with moderate correlations, suggesting an important systematic error. CONCLUSION: There is close agreement between the Framingham, PROCAM, and Dundee risk functions as regards average CHD risk, and moderate agreement for estimates within individuals. Taking PROCAM as the external standard, the Framingham function separates high and low CHD risk groups and is acceptably accurate for northern European populations, at least in men.
Adult↗
[Evaluation of SL-573 in acute purulent diseases in the field of orodental surgery--a double-blind method in comparison with mepirizole].
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Acute Disease↗
Multicenter evaluation of a new capillary blood prothrombin time monitoring system.
The analytical performance of the new capillary blood prothrombin time monitoring system CoaguChek was examined in a multicenter evaluation at six hospitals. The coefficients of variation of the INR obtained in the CoaguChek imprecision study were approximately 7% in the control plasma provided (within-run and day-to-day) and 4% in blood (within-run). The prothrombin times were ascertained in capillary blood (CoaguChek PT Test) and citrated venous plasma (Hepato Quick, Thromborel S) from 359 patients under oral anticoagulation therapy with phenprocoumon, acenocoumarin or warfarin. The agreement with the test results obtained with the comparison methods was acceptable versus Hepato Quick assay (n = 359; y = 1.23 x -0.49, r = 0.888) and good versus Thromborel S method (n = 359; y = 1.09 x -0.28, r = 0.895). A simplified assessment of all test results (n = 795) in a nine-field comparison table showed a concordance with the comparison methods of more than 80 (Hepato Quick: 81%, Thromborel S: 83%). The concordance between Hepato-Quick and Thromborel S was slightly higher (88%). Its good analytical performance and convenient handling recommend the CoaguChek system as a suitable system for decentralized prothrombin time testing.
Blood Chemical Analysis↗
Query3d: a new method for high-throughput analysis of functional residues in protein structures.
BACKGROUND: The identification of local similarities between two protein structures can provide clues of a common function. Many different methods exist for searching for similar subsets of residues in proteins of known structure. However, the lack of functional and structural information on single residues, together with the low level of integration of this information in comparison methods, is a limitation that prevents these methods from being fully exploited in high-throughput analyses. RESULTS: Here we describe Query3d, a program that is both a structural DBMS (Database Management System) and a local comparison method. The method conserves a copy of all the residues of the Protein Data Bank annotated with a variety of functional and structural information. New annotations can be easily added from a variety of methods and known databases. The algorithm makes it possible to create complex queries based on the residues' function and then to compare only subsets of the selected residues. Functional information is also essential to speed up the comparison and the analysis of the results. CONCLUSION: With Query3d, users can easily obtain statistics on how many and which residues share certain properties in all proteins of known structure. At the same time, the method also finds their structural neighbours in the whole PDB. Programs and data can be accessed through the PdbFun web interface.
Algorithms↗
[Hexoproline in broncho-obstructive syndromes: a double-blind method for comparison with orciprenaline].
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Bronchial Spasm↗
Lessons from the organization of a proficiency testing program in food microbiology by interlaboratory comparison: analytical methods in use, impact of methods on bacterial counts and measurement uncertainty of bacterial counts.
The proficiency testing program in food microbiology RAEMA (Réseau d'Analyses et d'Echanges en Microbiologie des Aliments), created in 1988, currently includes 450 participating laboratories. This interlaboratory comparison establishes proficiency in detection of Salmonella and Listeria monocytogenes, as well as enumeration of aerobic micro-organisms, Enterobacteriaceae, coliforms, beta-glucuronidase-positive Escherichia coli, anaerobic sulfito-reducing bacteria, Clostridium perfringens, coagulase-positive staphylococci, and L. monocytogenes. Twice a year, five units samples are sent to participants to assess their precision and trueness for enumeration and detection of micro-organisms. Most of participating laboratories use standard or validated alternative methods, they were 50-70% in 1994 and, for 5 years, they are 95%. An increasing use of alternative methods was also observed. This phenomenon is all the more significant as standard methods are laborious and time consuming; thus, 50% of the laboratories use alternative methods for the detection of Salmonella and L. monocytogenes. More and more laboratories use ready-to-use media and although the percentage is variable according to the microflora, we can consider that, today, 50-60% of the laboratories participating to the proficiency program only use ready-to-use media. The internal quality assurance programs lead also to an increasing use of media quality controls. The impact of analytical methods on bacterial counts was assessed by grouping together the results obtained by participating laboratories during the 10 last testing schemes from 1999 to 2003. The identified significant factors influencing enumeration results are variable from one microflora to another. Some of them significantly influence many microflora: the plating method (spiral plating or not) is influential for aerobic micro-organisms, Enterobacteriaceae, coliforms, and staphylococci, the type of culture medium and the medium manufacturer is influential for aerobic micro-organisms, Enterobacteriaceae, coliforms, E. coli, anaerobic sulfito-reducing bacteria, staphylococci, and L. monocytogenes. Others are specific of some micro-organisms: the resuscitation broth for L. monocytogenes, the mode of medium preparation for staphylococci and the incubation temperature for C. perfringens. These effects lead generally to small differences of about 0.1 log10 cfu g(-1), except for the enumeration of anaerobic sulfito-reducing bacteria, where the difference reaches 0.7 log10 cfu g(-1). These results, although difficult to extrapolate to all actual situations, which associate numerous food constituents and physiological states of bacteria to detect or numerate, allow nevertheless the quantification of interlaboratory variations linked to the methods in use. The analysis of bacterial counts obtained by the laboratories participating to the RAEMA proficiency testing program allowed also to validate a formula to calculate the repeatability of bacterial counts and to estimate the between-laboratory uncertainties for the majority of micro-organisms enumerated in food microbiology. The repeatability uncertainty is only indirectly affected by the method in use but depends essentially on the number of counted colonies. On the other hand, the between-laboratory uncertainty varies with the enumeration method in use, this variability is relatively small for the enumerations calling for methods without colony confirmation, i.e. for the enumeration of aerobic micro-organisms, Enterobacteriaceae, 'total' and thermotolerant coliforms, beta-glucuronidase-positive E. coli and coagulase-positive staphylococci with the technique using the rabbit-plasma fibrinogen agar. For these methods, the average between-laboratory standard deviation is 0.17 log10 cfu g(-1). The between-laboratory uncertainty is, on the contrary, larger for more complex techniques. For the enumeration of coagulase-positive staphylococci with the Baird-Parker agar, the between-laboratory standard deviation is equal to 0.23 log10 cfu g(-1), it is equal to 0.28 log10 cfu g(-1) for the enumeration of L. monocytogenes, to 0.34 log10 cfu g(-1) for the enumeration of C. perfringens, and to 0.47 log10 cfu g(-1) for the enumeration of anaerobic sulfito-reducing bacteria.
Bacteria↗
On dose distribution comparison.
In radiotherapy practice, one often needs to compare two dose distributions. Especially with the wide clinical implementation of intensity-modulated radiation therapy, software tools for quantitative dose (or fluence) distribution comparison are required for patient-specific quality assurance. Dose distribution comparison is not a trivial task since it has to be performed in both dose and spatial domains in order to be clinically relevant. Each of the existing comparison methods has its own strengths and weaknesses and there is room for improvement. In this work, we developed a general framework for comparing dose distributions. Using a new concept called maximum allowed dose difference (MADD), the comparison in both dose and spatial domains can be performed entirely in the dose domain. Formulae for calculating MADD values for various comparison methods, such as composite analysis and gamma index, have been derived. For convenience in clinical practice, a new measure called normalized dose difference (NDD) has also been proposed, which is the dose difference at a point scaled by the ratio of MADD to the predetermined dose acceptance tolerance. Unlike the simple dose difference test, NDD works in both low and high dose gradient regions because it considers both dose and spatial acceptance tolerances through MADD. The new method has been applied to a test case and a clinical example. It was found that the new method combines the merits of the existing methods (accurate, simple, clinically intuitive and insensitive to dose grid size) and can easily be implemented into any dose/intensity comparison tool.
Algorithms↗