SEARCH · PubMed Health

Results for “Repeatability and Reproducibility”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources

PubMedDate not supplied

Determination of nitrogen content in milk by the Kjeldahl method using copper sulfate: interlaboratory study.

Copper sulfate was substituted for mercury as the catalyst in the International Dairy Federation (IDF) Standard 20A:1986 method for the determination of nitrogen content in milk. The substitution was supported by results obtained in an interlaboratory study by 24 laboratories in 12 countries. Each laboratory analyzed 12 test samples of milk as blind duplicates in a double split level design with high, medium, and low nitrogen concentrations. The method protocol requires the concurrent analyses of an ammonium salt solution and a tryptophan solution as internal quality control standards with a minimum nitrogen recovery between 99 and 100% for the former and at least 98% for the latter. The repeatability and reproducibility relative standard deviations are 0.5 and 1%, respectively, for the range 0.35-0.70 g N/100 g. The performance of the laboratories that did not meet the required quality control specifications was clearly poorer than that of those that did meet the specifications.

Animals↗

PubMedDate not supplied

Liquid chromatographic determination of flucytosine in capsules: collaborative study.

A liquid chromatographic method for the determination of flucytosine in capsules was collaboratively studied by 7 laboratories. The method uses a C18 reverse phase column, water-methanol-acetic acid mobile phase containing 1-octanesulfonic acid sodium salt, p-aminobenzoic acid as internal standard, and photometric detection at 285 nm. The mean recovery value (+/- SD) of flucytosine from a synthetic formulation representing capsules was 99.2 +/- 1.72% (CV = 1.73%). Composited samples of 250 and 500 mg commercial capsules gave assay values of (mean +/- SD) 103.17 +/- 2.21 and 99.29 +/- 1.29% of declared, respectively. CV values were 2.15 and 1.30%. Reproducibility and repeatability CVs were 2.19 and 1.50%, respectively, for the 250 mg capsules, and 1.34 and 0.63%, respectively, for the 500 mg capsules. The method has been adopted official first action.

Capsules↗

PubMed1988

Vitamin C in leukemia and preleukemia cell growth.

Vitamin C was shown to be an essential requirement for the growth of mouse myeloma cells in an in vitro colony assay. Human leukemia (acute nonlymphocytic leukemia) cell colonies grow well in a similar in vitro culture system, and vitamin C has been shown to enhance the growth of leukemic cell colonies in 77 (35%) of 219 leukemic patients while none of 34 normal bone marrows tested simultaneously shows growth enhancement by this vitamin. This vitamin C effect is reproducible in repeated experiments in same patients, specific to this vitamin, selective for leukemic cells, and is proven to be biological in nature. Further, leukemic cells are mobilized back and forth between cycling and resting states with vitamin C supplementation/depletion. Our more recent study indicates that the preleukemia (myelodysplastic syndrome), generally known to be related to acute nonlymphocytic leukemia, has similar pattern in terms of vitamin C sensitivity, with 8 of 25 patients (32%) showing the growth enhancement with this vitamin.

Ascorbic Acid↗

PubMed1986

Determination of estrogen receptor in breast cancer using monoclonal antibody technology: results of a multicenter study in the United States.

Three laboratories compared their routine steroid binding assays with the Abbott estrogen receptor-enzyme immunoassay (ER-EIA) to determine ER in breast cancer cytosols. Each laboratory was first trained to use the ER-EIA kit and then performed routine proficiency panels to determine assay reproducibility. The frozen panels prepared from MCF-7 cytosol produced good intraassay results but the between assay coefficients of variation were frequently above 10%. Lyophilized MCF-7 cytosols produced better reproducibility upon repeated assay. One laboratory demonstrated that New England Nuclear steroid binding kits and the ER-EIA produced comparable results when MCF-7 lyophilized cytosols were used. The analysis of breast tumor samples demonstrated excellent linear correlation coefficients for each laboratory (greater than 0.92 N approx. 60 samples each) but different slopes. The comparison of the ER-EIA with the New England Nuclear steroid binding assay produced a slope of 1.13. The ER-EIA appears to produce comparable results to the conventional steroid binding assays for the determination of ER in breast tumor cytosols.

Antibodies, Monoclonal↗

PubMedDate not supplied

Colorimetric determination of alkaline phosphatase as indicator of mammalian feces in corn meal: collaborative study.

In the official method for rodent filth in corn meal, filth and corn meal are separated in organic solvents, and particles are identified by the presence of hair and a mucous coating. The solvents are toxic, poor separation yields low recoveries, and fecal characteristics are rarely present on all fragments, especially on small particles. The official AOAC alkaline phosphatase test for mammalian feces, 44.181-44.184, has therefore been adapted to determine the presence of mammalian feces in corn meal. The enzyme cleaves phosphate radicals from a test indicator/substrate, phenolphthalein diphosphate. As free phenolphthalein accumulates, a pink-to-red color develops in the gelled test agar medium. In a collaborative study conducted to compare the proposed method with the official method for corn meal, 44.049, the proposed method yielded 45.5% higher recoveries than the official method. Repeatability and reproducibility for the official method were roughly 1.8 times more variable than for the proposed method. The method has been adopted official first action.

Alkaline Phosphatase↗

PubMed1986

Changes in pulmonary adenosine triphosphate-binding proteins detected by nucleotide photoaffinity labeling following treatment of mice with the tumor-modulatory agent butylated hydroxytoluene.

Protein kinases play a central role in the regulation of normal and neoplastic growth. A novel approach to evaluating this role is to apply the photoaffinity analogue of adenosine 5'-triphosphate (ATP), 8-azido[gamma-32P]adenosine 5'-triphosphate (8-N3-[gamma-32P]ATP), to extracts obtained from nondividing and dividing tissues in order to label high affinity ATP receptors, including protein kinases. A pattern of ATP-binding proteins was observed on autoradiograms prepared from lung extracts which were reproducible upon repeated experimentation and was identical among extracts prepared from several inbred strains. Seven specifically photolabeled proteins were detected with molecular weights of 120,000, 84,000, 53,000, 51,000, 43,000, 41,000, and 33,000. The pneumotoxicity that results from treating mice with butylated hydroxytoluene (BHT) is followed by a stimulation of lung cell proliferation as part of the regenerative repair phase. Increased photoincorporation of 8-N3-[gamma-32P]ATP into proteins with molecular weights of 41,000, 37,000 and 33,000 resulted from BHT treatment. The following correlations between increased photoincorporation and lung repair, as defined by an increased lung weight/body weight ratio, were observed: (a) these changes shared a similar BHT dose dependency; (b) both followed the same time course and were reversible; (c) both lung damage and enhanced photolabeling were abolished if the mice were pretreated with cedrene, an inducer of drug-detoxifying enzymes; (d) the effect of BHT on ATP-binding proteins was agent specific, since urethan treatment did not affect photoincorporation. These results demonstrate that the specific photolabeling of ATP receptors in tissue extracts is a sensitive indicator of a particular growth-related repair process.

Actins↗

PubMedDate not supplied

Gas chromatographic determination of deoxynivalenol in wheat with electron capture detection: collaborative study.

Ten laboratories participated in a collaborative study of a method for the determination of deoxynivalenol in wheat by gas chromatography with electron capture detection. Each laboratory analyzed 6 samples in duplicate. Each collaborator received samples spiked at the 100.3, 501.3, and 1002.6 ng/g levels; a control sample; and 2 naturally contaminated samples. The average recovery (outliers excluded) for the spiked samples was 92.2%. The mean repeatability and reproducibility, respectively, were 32.2 and 41.3% for the spiked samples and 30.9 and 47.6% for the naturally contaminated samples. The method was adopted official first action.

Chromatography, Gas↗

PubMed1987

The plain chest X-ray in acquired heart disease in adults.

The chest X-ray is a cheap, easily repeatable and reproducible method of investigating the structure and function of the heart. While it is rarely of decisive diagnostic importance in the setting of modern methods of noninvasive investigation, it is valuable in evaluating the severity of cardiac pathology and also in revealing unsuspected abnormalities which may complicate management. For this reason all patients should have a chest X-ray, preferably both frontal and lateral, at the first attendance for cardiac evaluation. In most cardiac departments a routine frontal chest X-ray is taken at each outpatient appointment.

Adult↗

PubMed1977

High pressure liquid chromatographic determination of 4,4'-(diazoamino)-dibenzenesulfonic acid in FD&C yellow no. 6.

Fourteen analysts from 9 laboratories evaluated a high pressure liquid chromatographic procedure for the determination of 4,4'-(diazoamino)-dibenzenesulfonic acid (DAADBSA) in FD&C Yellow No. 6. Each collaborator analyzed 5 samples nominally containing 0-0.050% DAADBSA. The repeatability and reproducibility of the method are estimated to be 0.003% and 0.020%, respectively. The method has been adopted as offical fist action.

Azo Compounds↗

PubMedDate not supplied

Liquid chromatographic determination of colchicine in pharmaceuticals: collaborative study.

A liquid chromatographic (LC) method for the determination of colchicine in pharmaceutical dosage forms and the bulk drug was evaluated in an interlaboratory study which included 13 participating laboratories. The method involves extraction (or dissolution) of the active ingredient with methanol-water (1 + 1), followed by filtration of the extract and reverse phase LC using an octylsilane bonded phase column and UV detection at 254 nm. The mobile phase consists of a methanol-phosphate buffer mixture (pH = 5.5). Three commercial tablet formulations (0.5-0.6 mg colchicine/tablet), 1 synthetic injectable preparation (0.510 mg colchicine/mL), and 1 bulk drug sample were assayed in duplicate by the proposed method. The reproducibility and repeatability standard deviations based on nonpooled results for each sample ranged from 0.0062 mg/mL to 0.0147 mg/tablet and from 0.0037 mg/mL to 0.0127 mg/tablet, respectively; the corresponding coefficients of variation ranged from 1.21 to 2.54% and from 0.73 to 2.19%, respectively. The mean recovery from the synthetic injectable formulation was 100.0%. The method has been adopted official first action.

Chromatography, Liquid↗

PubMedDate not supplied

Analysis of fat-soluble vitamins. XXIX. Liquid chromatographic determination of vitamin D in AD concentrates: collaborative study.

A simplified liquid chromatographic (LC) method for determining vitamin D in vitamin AD concentrates (greater than or equal to 5000 IU vitamin D/g) was collaboratively studied. In the simplified method, the 2 columns specified in AOAC LC method 43.101-43.109 are replaced by a single column, which separates the vitamin D isomers and the vitamin A esters. The procedure for oils includes dissolution and quantitation by normal phase LC. Dry multivitamin concentrates and aqueous dispersions are treated with an enzyme system and the vitamins are extracted with n-pentane. Six coded samples were distributed to 16 laboratories; 15 collaborators returned their results. Estimates of repeatability and reproducibility for the oil samples were 1.1 and 3.1%, respectively; for the high-level concentrated dry preparation 1.4 and 3.9% and for the low-level concentrated dry preparation 1.3 and 11.4%, respectively. These values are a considerable improvement over the results obtained in the 1979 multivitamin collaborative study. The method has been adopted official first action for determination of vitamin D in vitamin AD concentrates containing greater than or equal to 5000 IU vitamin D/g.

Chromatography, Liquid↗

PubMed1985

[Experimental measurements of renal circulation using digital functional angiography].

New techniques of digital image processing have been experimentally tested for the assessment of renal blood flow. The underlying principle in functional angiography is the extraction of flow parameters. Basically, density-time variations of the contrast medium are analyzed from each picture element of a 256 X 256 matrix. The real-time acquisition rate of images was 25/sec. For the calculation of angiographic flow a PDP 11/40 computer was used to interactively perform a time dependent segmentation of the renal arteries and the aorta. Subsequently, volume flow was calculated in relative units for the specific vascular segments under study. 15 control angiograms were made in 5 animals with cardiac output ranging between 0.8 to 2.2 l/min. Unilateral renal blood flow was calculated as 24 +/- 3.4% of pre-renal aortic flow without systematic side differences. Reproducibility from repeated flow measurements showed an SD of +/- 1.8% of the individual pre-renal aortic flow. Renal flow was also measured in 3 animals with an experimentally created 50% flow reduction of the left kidney. Angiographic flow in the left renal artery dropped to 12 +/- 2% of pre-renal flow. The present experimental data suggest that digital angiography has sufficient diagnostic capabilities for the detection of abnormal renal blood flow. The technique may serve as a useful diagnostic adjunct to conventional angiography and has the potential of assisting in the evaluation of renal vascular hypertension.

Angiography↗

PubMedDate not supplied

[Value of isotopic methods in the diagnosis of myocardial infarction of the right ventricle].

In the left ventricle, isotope techniques can be used to study the perfusion of the myocardium or the ventricular function. Because of the thinness of the walls of the right heart, the classical examinations and Thallium 201 perfusion cannot be used to demonstrate a disorder of perfusion in the right ventricle. Nevertheless, it is possible, with the aid of Technetium 99m labeled pyrophosphate, to diagnose and localise necrosis of the inferior wall with an acceptable degree of sensitivity, during the acute phase of the infarction. However, the major value of isotope techniques is to evaluate right ventricular function by determining the value of the global ejection fraction and the kinetic anomalies of the different walls. These methods, together with echocardiography, allow the diagnosis of lesions of the inferior part of the right ventricle in patients with inferior necrosis... Furthermore, because these methods allow quantification and because they are reproducible and repeatable, they can be used to follow the course of the right ventricular function in response to treatment.

Evaluation Studies as Topic↗

PubMedDate not supplied

[Effect of an intravenously administered phosphatidylserine emulsion on blood coagulation and blood system indices].

Experiments on white rats and rabbits showed that intravenous injection of phosphatidylethanol amine- and sphyngomyelin-stabilized phosphatidylserin emulsion produced hypocoagulemia. The effect was observed immediately after injection of the drug, reached a maximum after one hour and returned to normal following 24 hours. The changes became more intensive as the dose was increased and could be reproduced during repeated administrations over a period of ten days. The arterial blood pressure, velocity of the blood flow and volume of the circulating blood remained unchanged. There were no appreciable changes in the peripheral blood parameters or in bone marrow hemopoiesis on repeated administrations over a period of thirty days.

Animals↗

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

[The syndrome of auditory agnosia. A case report and an attempt of neuropsychological qualification (author's transl)].

Proceeding from the neuropsychological examination of a patient with an exceptionally selective impairment of auditory gnosis of vascular origin, we make an attempt to analyze structurally the syndrome of auditory agnosia, a study of which has been neglected in comparison with analyses of visual agnosia. In our analysis we refer to 28 case reports, documented in the literature. Decisive syndromal points of view are: a) there is an absence of significant audiological deficiencies; b) errors of the acoustic-discriminative type prevail in auditory-visual matching tasks; c) the gnostic deficit is modality specific; d) the same items are variably reproduced on repeated presentation; e) there is marked fluctuation of performance; f) there is exceptional irreversibility of the impairment; g) amusia is a more or less obligatory accompanying phenomenon; h) in cases of vascular origin there is always a history of repeated temporal lobe damage, this damage being predominantly in the form of bilateral lesions. This analysis indicates a close structural analogy to the syndrome of perceptive visual agnosia. We place great importance in the relationship between approaches and models of cognitive psychology (Neisser, 1967) which we see as important for further theoretical development in neuropsychology.

Adolescent↗

PubMed1983

Filament hygrometer for water activity measurement: interlaboratory evaluation.

A method is presented for measuring water activity (aw) of foods with a filament hygrometer. An interlaboratory evaluation carried out for the Nordic Committee on Food Analysis demonstrated that measurements can be made with a repeatability and reproducibility of 0.005 and 0.010 aw, respectively. The critical parameters of aw measurements are defined and discussed in relation to the accuracy and reproducibility required. The need for strictly standardized procedures for maintenance of the equipment, sample treatment, calibration, and measuring is emphasized.

Food Analysis↗

PubMedDate not supplied

Liquid chromatographic determination of methyldopa and methyldopa-thiazide combinations in tablets: collaborative study.

A reverse phase liquid chromatographic method for the determination of methyldopa, methyldopa-hydrochlorothiazide, and methyldopachlorothiazide in tablets was collaboratively studied by 8 laboratories. Each collaborator received 20 samples that included drug substance, synthetic and commercial tablet compositions. The overall repeatability and reproducibility standard deviations for commercial tablets were 1.11 and 1.75% for methyldopa, 0.96 and 1.62% for chlorothiazide, and 1.21 and 2.15% for hydrochlorothiazide, respectively. The overall recoveries of methyldopa, chlorothiazide, and hydrochlorothiazide added to synthetic tablets were 100.78, 100.70, and 101.34%, respectively. The method has been adopted official first action.

Chlorothiazide↗