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PubMedDate not supplied

Comparison of two immunochemical methods with thin-layer chromatographic methods for determination of aflatoxins.

Three different methods were compared for the determination of total flatoxins in corn and peanuts naturally contaminated with aflatoxins and in corn, peanuts, cottonseed, peanut butter, and poultry feed spiked with aflatoxins B1, B2, and G1. The 3 methods were an enzyme-linked immunosorbent assay (ELISA) screening test; a monoclonal antibody-affinity column-solid-phase separation method; and the AOAC official thin-layer chromatography (TLC) methods for all except poultry feed, for which Shannon's TLC method for mixed feed was used. The ELISA test is designed to provide only positive results for total aflatoxins at greater than or equal to 20 ng/g or negative results at less than 20 ng/g. The affinity column separation is coupled with either bromination solution fluorometry to estimate total aflatoxins or liquid chromatography (LC) to quantitate individual aflatoxins. Fluorodensitometry was used to determine aflatoxins in commodities analyzed by the TLC methods. The LC and TLC results were in good agreement for all the analyses. The results for the affinity column using bromination solution fluorometry were similar except those for cottonseed, which were about 60% higher. The ELISA screening method correctly identified naturally contaminated corn and peanut positive samples. No false positives were found for controls. The correct response for spiked corn, raw peanuts, peanut butter, and cottonseed at greater than or equal to 20 ng aflatoxins/g was about 90%. The correct response for spiked poultry feed at greater than or equal to 20 ng aflatoxins/g was about 50%.

Aflatoxins↗
PubMed1989

[Enhancement of enamel crystallinity with gel method during orthodontic treatment. The 2nd report: application of micro-area X-ray diffraction method].

This study is to review an effect on the improvement of enamel crystallinity with gel method in the course of orthodontic treatment by applying gelatin gel method (group II) as well as silica-hydro gel method (group I) to bracket-bonded enamel surfaces of extracted teeth and for a relative review, the chopped cross sections of the above teeth were analyzed by the method of micro area X-ray diffraction. The results obtained were as follows: 1. As a result of identifying by the method of microarea X-ray diffraction, the present of hydroxyapatite, Ca5(PO4)3OH and fluorapatite, Ca5(PO4)3F was recognized at any section of every group. 2. In making a relative study of the variation of line profile and peak shift, an outstanding difference was not acknowledged in line profile, however, peak shift in the direction of high angle side was indicated on the experimental side of each group and a tendency for peak shift was more noticeable near by enamel cuticle. At boundary sites and on the control side, the variation was only shown in one part of group II. Also a tendency for peak shift in the direction of high angle side was recognized in group I rather than in group II. From the foregoing results, it was found to be effective to improve tooth substance of the bracket-bonded enamel and in that event, the silica-hydro gel method was suggested to be superior to the gelatin gel method. Also with the regard to the bracket-bonded sides, tooth substance was noticeably improved at enamel cuticle but not sufficiently improved at sites underneath the brackets and at boundary sites of the both, therefore, one of the future subjects would be to review such areas.

Apatites↗
PubMed1989

[Confidence factors-method for estimating the confidence limits of standardized population rate of indirect method].

The standardized rate of indirect method is widely used, but no method of interval estimation for its population rate has been reported. The authors have discussed the standard error of standardized rate of indirect method and suggested that a method using this standard error should be used to determine the confidence limits for the population rate. In this paper, the authors put forward another method (Confidence Factors-Method) which can be easily applied to determine the confidence limits. It gives approximately the same result with the method mentioned above.

Mathematics↗
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↗
PubMed1981

Comparison of Eustachian tube function measured by the microflow method and a new quantitative impedance method.

Eustachian tube function in 25 applicants for flight training was tested during simulated flights using two methods alternately; the integrating microflow method with a stationary pressure chamber, and a new quantitative impedance method in combination with a new mobile pressure chamber. All ears were tested by both methods. The results of the various tests did not differ significantly between methods. The reliability of the measurements was good and almost equal in both methods. Several practical advantages with the new impedance method in combination with the mobile pressure chamber make it preferable.

Acoustic Impedance Tests↗
PubMed1981

[Evaluation of methods to determine the vitamin B6 status of humans. 1. alpha-EGOT: methods and validation].

A semiautomatic method to determine the activation coefficient of the glutamic-oxaloacetic-transaminase in the erythrocytes is described. This method is compared with other methods and possible sources of error are discussed. Colorimetric methods show considerable disadvantages, such as lack of precision or unspecific hydrazone formation. The kinetic tests avoid these problems. This is in part due to the fact that enzyme stimulation by excessive PLP-addition as used in our procedure bears practical and theoretical advantages. Nevertheless, comparison with published data on vitamin B6 status remains difficult because of insufficient standardization of the used methods. To validate our method we performed experiments testing the stability of the samples, short-term physiological changes and influence of the chelating agent EDTA on transamination. Heparinised blood samples can be stored only for one day with changing at 4 degrees C or room temperature. Storing of the erythrocytic suspension at deep-freezing temperature (-18 degrees C) leads to considerable changes of results. When kept under liquid nitrogen there is no change of the alpha-values for at least 45 days. The addition of EDTA to the samples is known to exclude the influences of cations, such as non enzymatic transamination of a direct alteration of the enzyme activity and therefore EDTA should be added to improve standardisation of the method. The described procedure is a fast, reliable and precise way to determine the alpha-EGOT.

Aspartate Aminotransferases↗
PubMed1994

Candidate reference method for determining serum theophylline applied to target-setting in external quality assessment and routine method evaluation.

We present a candidate reference method for the determination of serum theophylline by isotope dilution gas chromatography-mass spectrometry, using extractive alkylation in sample preparation. The maximum method bias was < 1.0%. The mean method imprecision (CV) was 0.63% (range 0.37-0.96%), calculated from the results of six measurements independently performed on 3 days. The maximum total error of the method, including the method bias and 95% confidence interval, was < 2.1%. Investigation of various substances and metabolites for interference proved the specificity of the proposed method. The method was used to evaluate three routine assays by linear regression analysis. Performance of the TDx II (Abbott) was excellent and of the Emit 2000 (Syva) assay was good. The Kodak Ektachem assay showed a high dispersion of results and a pronounced positive bias in the subtherapeutic range.

Evaluation Studies as Topic↗
PubMed1993

[Length method in evaluating right ventricular volume in children with congenital heart disease: a comparison with two dimensional echocardiographic method].

The accuracy and reliability of two-dimensional echocardiographic length method in right ventricular volume measurement were assessed by three-dimensional echocardiographic method in 10 normal children, 10 patients with atrial septal defect, and 10 patients with pulmonary stenosis. Their age and sex were matched. Right ventricular end diastolic, end systolic, mid-systolic volume, and ejection fraction evaluated by length method were correlated very well with the values obtained by three-dimensional echocardiographic method in normal and pulmonary stenosis group (r = 0.71-0.95, P < 0.01). In atrial septal defect group, right ventricular volume obtained by the two methods was correlated well (r = 0.86-0.95, P < 0.01). Although the correlation in right ventricular ejection fraction was lower, it was still significant. The shortening rate of X, Y, Z parameters required by length method were similar in each group: delta Z % > delta X % > delta Y %. We conclude that right ventricular volume and function could be assessed accurately by two-dimensional echocardiographic length method in children with right ventricular volume or pressor overloaded, and that right ventricular systolic pattern is similar in those situations.

Child, Preschool↗
PubMed1995

A comparison of a 30-cluster survey method used in India and a purposive method in the estimation of immunization coverages in Tamil Nadu.

A 30-cluster survey method that is employed for estimating immunization coverages by the Government of India (GOI) was compared with a Purposive method, to investigate whether the likely omission of SC/ST and backward classes in the former would lead to the reporting of higher coverages. The essential difference between the two methods is in the manner in which the first household is selected in the chosen first stage sampling units (villages). With the GOI method, it is often close to the village centre, whereas with the Purposive method it is always in the periphery or in a pocket consisting of SC/ST or backward classes. A concurrent comparison of the two methods in three districts in Tamil Nadu showed no real differences in the coverage with DPT and BCG vaccines. However, the coverage was consistently higher by the GOI method in the case of the Polio vaccine (by 1.5%, 3.1% and 5.3% in the 3 districts), and the Measles vaccine (by 4.8%, 13.3% and 13.9%); the average difference was 3.3% for Polio vaccine (p = 0.08) and 7.3% for Measles vaccine (p = 0.01).

Analysis of Variance↗
PubMed1997

Collection of pancreatic juice from growing pigs. A comparative study of the pouch method and the catheter method.

CONCLUSION: The results of this study demonstrate that there are large differences in the amount of pancreatic juice secreted and in the chemical and enzymatic composition of pancreatic juice when the pouch and the catheter methods were used, and these differences must be taken into consideration in future studies with either method. METHODS: A study was performed to compare the two most commonly used methods to collect pancreatic juice from growing pigs; namely, the pouch method (PM) and the catheter method (CM). In the first part of the study, three barrows (initial weight 37 kg) were fitted with a pancreatic pouch re-entrant cannula. An isolated pouch was prepared in which the pancreatic duct enters the duodenum. In the second part of the study, also with three barrows (initial weight 32 kg), a catheter was inserted into the pancreatic duct. RESULTS: At several points during the 24-h collection, the hourly rate of pancreatic juice secretion in CM pigs was larger (p < 0.05) than for PM pigs. CM pigs also had a higher (p < 0.05) daily volume of secretion, 4.09 vs 2.63 L/24 h for PM pigs. The pH of pancreatic juice collected from CM pigs was consistently higher (p < 0.01) throughout the 24-h collection. In contrast, the concentration and daily output of bicarbonate did not differ between CM and PM pigs. The concentration of protein in pancreatic juice from PM pigs (7.21 g/L) was higher (p < 0.001) than for CM pigs (4.08 g/L). Specific amylase and lipase and total amylase activities were greater (p < 0.01) in pancreatic juice collected from PM pigs. Specific and total carboxyl ester hydrolase and colipase activities were substantially (p < 0.01) larger in pancreatic juice collected from CM pigs. A major difference between the methods was that trypsin and chymotrypsin were fully active in pancreatic juice from PM pigs, whereas virtually no trypsin or chymotrypsin activity was detected in pancreatic juice from CM pigs. Specific and total chymotrypsin activities did not differ between PM and CM pigs. Both specific and total trypsin activities were substantially higher in pancreatic juice from CM pigs: 3682 U/L and 12,752 U/24 h, respectively, vs 1031 U/L and 2639 U/24 h, respectively, in pancreatic juice from PM pigs.

Animals↗
PubMedDate not supplied

Extension of dry ash atomic absorption and spectrophotometric methods to determination of minerals and phosphorus in soy-based, whey-based, and enteral formulae (modification of AOAC Official Methods 985.35 and 986.24): collaborative study.

Eight laboratories participated in a collaborative study of AOAC Official Method 985.35, Minerals in Ready-to-Feed Milk-Based infant Formula and Pet Foods, Atomic Absorption Spectrophotometric Method; and 7 laboratories participated in a study of AOAC Official Method 986.24, Phosphorus in Milk-Based infant Formula, Spectrophotometric Method, to extend these methods to infant formulae (other than milk-based) and enteral products. Three ready-to-feed soy-based formulae and 2 soy-based powder formulae were chosen to represent the plant matrix. A whey-based formula and a casein-based enteral formula were also included in the study. Soy formulae containing nearly identical concentrations of particular elements were matched, and an application of the Youden "closely matched pair" approach was used to estimate repeatability parameters. Average reproducibility values were as follows: calcium, 9.3%; copper, 9.7%; Iron, 5.5%; potassium, 4.0%; magnesium, 5.2%; manganese, 10.6%; sodium, 4.7%; phosphorus, 10.5%; and zinc, 7.3%. At similar analyte concentrations, the between-laboratory variabilities compared well with those reported for the official methods. Most repeatability and reproducibility parameters compared well with the original collaborative study. AOAC Official Methods 985.35 and 966.24 have been modified to extend their applicability to infant formulae (other than milk-based) and enteral products.

Animal Feed↗
PubMed1997

Graphical interpretation of analytical data from comparison of a field method with reference method by use of difference plots.

Various viewpoints have been offered regarding the appropriate use of scatter plots or difference plots (bias plots or residual plots) in comparing analytical methods. In many of these discussions it seems the basic concepts of identity (within inherent imprecision) and acceptability based on analytical goals (analytical quality specifications) have been forgotten. With the increasing number of Reference Methods in laboratory medicine, these basic concepts are becoming more important in validation of field methods. Here we describe a simple and effective graphical test of these hypotheses (identity and acceptability) by use of difference plots. These plots display the underlying hypothesis before the measured differences are plotted and allow interpretation of the results according to specific criteria. We further describe simple but effective interpretations of the data, when the hypothesis is not fulfilled, by using two data sets drawn from comparisons of field methods for S-creatinine with a Reference Method for this analyte. The difference plot is a graphical tool with related simple statistics for comparison of a field method with a Reference Method, focusing on (a) identity within the inherent analytical imprecision or (b) acceptability within analytical quality specifications. Calculation of the standard deviation of the differences is an indispensable tool for evaluation of aberrant-sample bias (matrix effects).

Chemistry, Clinical↗
PubMed1998

The accuracy of laboratory measurements in clinical chemistry: a study of 11 routine chemistry analytes in the College of American Pathologists Chemistry Survey with fresh frozen serum, definitive methods, and reference methods.

CONTEXT: Better procedures are needed whereby national proficiency testing survey providers can assess and improve the accuracy of laboratory measurements in clinical chemistry. SETTING: The 1994 College of American Pathologists Comprehensive Chemistry Survey. DESIGN: This study of matrix effects and the accuracy of laboratory measurements for 11 analytes linked the logistics of the Survey to definitive methods at the National Institutes of Standards and Technology, reference methods at the Centers for Disease Control and Prevention, proficiency testing materials, and a fresh frozen serum sample. The data were analyzed with a statistical model of laboratory measurements. RESULTS: (1) Matrix biases affected the results reported from 69% of the 644 peer group/survey specimen pairs evaluated. (2) Because of matrix biases, the reference value was the correct target value only 32% of the time; thus, the traceability established by definitive method and reference method value assignments on Chemistry Survey specimens did not assure accuracy on patient samples. (3) In contrast to matrix biases, the error caused by random matrix effects with proficiency testing samples was about the same as that caused by random specimen effects with fresh frozen serum, and both were less than within-run random analytic error. (4) Calibration biases occurred in 73% of the 180 peer groups evaluated, and, after matrix biases were removed, the total variance of interlaboratory measurements was due to peer group calibration bias (48%), within-peer-group random calibration error (31 %), within-run random error (14%), and random specimen effects (7%). CONCLUSIONS: An opportunity exists to improve method calibration accuracy in clinical chemistry. With improved design, national proficiency testing surveys can monitor and help reduce method calibration error by converting reported survey results to a true accuracy base that predicts accuracy on patient samples. For medical purposes, the correct target values on artificial (matrix-modified) chemistry materials are reference values adjusted for the matrix bias of each peer group. Matrix biases estimated by the use of fresh frozen serum can be used as factors to transfer the accuracy of definitive methods from artificial reference materials to patient samples.

Bias↗
PubMed1998

Torso loading via a harness method activates trunk muscles less than a hand loading method.

There is a need for data comparing muscle activity under equivalent moments at the torso using different loading methods. In torso biomechanics, it is often necessary to apply moments to people and then measure or predict the muscle activity in response to the external load. Alternative methods exist to generate moments including applying forces by a chest harness and loads held in the hands. The limitation of previous research has been to use only one of the loading methods, generally harness loading, assuming it produces muscle activity equal to when loads are held in the hands. The objective of the this study was to test if equivalent moments at L3/L4 applied to subjects through two loading methods resulted in the same muscle activity. Subjects maintained a static posture while attempting a combination of flexion/extension, lateral bending, and torsion to counter the external loads applied via hand and harness loading methods. Hand and harness loading did not result in equal muscle activity as measured by electromyographic techniques. The left and right latissimus dorsi had increases in activity (16-25%) when loads were held with the hands instead of applied via the harness. Increased activity for hand loading was also found for the left and right rectus abdominis (13-17%) and left external oblique (24%). The left and right erector spinae and right external oblique exhibited the same activity for both loading methods. The current findings indicate that studies of torso loading using a shoulder harness to create torso moments may be lowering activity of some torso muscles.

Adult↗
PubMed1994

Method switching and not using modern methods lead to abortions in Mauritius.

Contraceptive prevalence in Mauritius (76%) is among the highest in the world. Yet, it is estimated that each year there are some 20,000 cases of induced abortion, which is illegal in the country. A study based on a sample of 475 women admitted to three hospitals with complications due to induced abortion revealed considerable use of unreliable methods (e.g., withdrawal and natural methods), frequent method switching, and inconsistent use of modern methods. The study also found that women seeking abortion were usually under 30 years of age, and 20% of women with abortion complications were not using any method, and some 50% were using an unreliable method at the time they became pregnant. It emerged that with increasing numbers of women employed, their work schedules hindered their going to a family planning clinic and resulted in abortion being used as a back-up to contraception failure. Among the women with abortion complications, 25% had already had a previous abortion. These findings came as a big surprise to the family planning services. To discuss the findings, a national symposium was held in July, 1993. The symposium was attended by government ministers, members of parliament, and international personalities in the field of family planning. A discussion of the results of the study also took place in the National Assembly, where a motion was tabled to decriminalize abortion. The findings also facilitated, albeit indirectly, the approval of Norplant in the country.

Abortion, Induced↗
PubMed1979

[Critical study of methods of estimation by an enzymatic method of serum triglycerides (author's transl)].

The authors describe a critical study of two entirely enzymatic methods of determination of serum triglycerides which differ mainly by the choice of hydrolytic agents: esterase and hydrolase by the Roche methods, lipase and esterase in the case of the Boehringer method. The estimation of the resulting free glycerol requires 3 sequential enzymatic reactions (glycerol kinase, pyruvate kinase, lactate dehydrogenase, ending by the measurement of the consumed reduced NAD. The study of the kinetics of the analysis in two stages is carried out using standard solutions of glycerol and with human sera of variable concentration; the optimal conditions of the reaction time and temperature are drawn up. The trials of repeatability and reproducibility from day to day were carried out together with evaluation of the precision. The method was compared with Beohringer's method (n = 50) using hydrolysis of alcoholic potash. The authors conclude on the use of the methods studied.

Esterases↗
PubMed1977

Combined gel filtration, biuret/copper method compared with an immunochemical method for urinary protein measurement.

We compared an immunochemical method specific for plasma proteins with a chemical method, in which interfering substances are separated by gel filtration and "total" urinary protein is determined by the biuret reaction followed by reaction of protein-bound copper with diethyldithiocarbamate after a second gel filtration to remove nonprotein-bound copper. More than 250 24-h urine samples were analyzed by each method. There was linear agreement and a correlation of 0.96 between the two methods, but urinary protein values determined by the immunochemical method, especially for patients with multiple myeloma, were lower than by the chemical method.

Chromatography, Gel↗