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Results for “Repeatability and Reproducibility”

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PubMed1995

Use of the rhesus monkey as an experimental model to test the degree of efficacy of an anti-sporozoite peptide malaria vaccine candidate combined with copolymer-based adjuvants.

Humoral response against sporozoites is not effective in protecting individuals from getting malaria. Reduction in the infectivity of sporozoites has not been quantified for most anti-sporozoite vaccines tested. Quantification requires animal models providing predictable prepatent periods, e.g., time elapsed between sporozoite inoculation and detection of parasitemia, to be used as an indicator of activity against sporozoites. A delay in prepatent period from vaccinated animals would therefore reflect a protective effect in reducing the number of parasites. We report the vaccination of rhesus monkeys with a synthetic peptide reproducing part of the repeated region of the circumsporozoite protein of Plasmodium cynomolgi. This peptide was conjugated to the carrier protein diphtheria toxoid and injected with four adjuvant formulations that differed only by the type of emulsion or immunomodulator. Because all five control animals had a synchronous prepatent period after challenge with live sporozoites, it was possible to quantify the protective efficacy for each vaccine formulation, even though all monkeys developed parasitemia. Sporozoite elimination correlated with the immunomodulator and the type of emulsion. Such elimination was related neither to antibody titer against the immunizing peptide or the whole sporozoite, nor to antibody isotype induced by the vaccine formulation.

Adjuvants, Immunologic↗

PubMed2004

A validated PCR-based method to detect Listeria monocytogenes using raw milk as a food model--towards an international standard.

A PCR assay with an internal amplification control was developed for Listeria monocytogenes. The assay has a 99% detection probability of seven cells per reaction. When tested against 38 L. monocytogenes strains and 52 nontarget strains, the PCR assay was 100% inclusive (positive signal from target) and 100% exclusive (no positive signal from nontarget). The assay was then evaluated in a collaborative trial involving 12 European laboratories, where it was tested against an additional 14 target and 14 nontarget strains. In that trial, the inclusivity was 100% and the exclusivity was 99.4%, and both the accordance (repeatability) and the concordance (reproducibility) were 99.4%. The assay was incorporated within a method for the detection of L. monocytogenes in raw milk, which involves 24 h of enrichment in half-Fraser broth followed by 16 h of enrichment in a medium that can be added directly into the PCR. The performance characteristics of the PCR-based method were evaluated in a collaborative trial involving 13 European laboratories. In that trial, a specificity value (percentage of correct identification of blank samples) of 81.8% was obtained; the accordance was 87.9%, and the concordance was 68.1%. The sensitivity (correct identification of milk samples inoculated with 20 to 200 L. monocytogenes cells per 25 ml) was 89.4%, the accordance was 81.2%, and the concordance was 80.7%. This method provides a basis for the application of routine PCR-based analysis to dairy products and other foodstuffs and should be appropriate for international standardization.

Animals↗

PubMed1999

A validation study for the extraction and analysis of DNA from human nail material and its application to forensic casework.

A validation study was conducted to demonstrate that deoxyribonucleic acid (DNA) could be successfully extracted from human nail material and analyzed using short tandem repeat (STR) profiling and/or mitochondrial DNA (mtDNA) sequencing. This study involved the development of a DNA extraction protocol that includes a cleaning procedure designed to remove external contaminants (e.g., biological, chemical). This protocol was used to test human nail material that had been soaked in whole blood from a second donor and coated with gold-palladium to simulate scanning electron microscopic analysis. The results showed no indication of a mixture and were consistent with that of the nail donor. Fresh human nail material usually yielded both STR profiles and mtDNA sequence information; however, aged human nail material (approximately eight years old) yielded only mtDNA sequence information. Upon completion of the validation study, the extraction protocol was used for the analysis of a torn fingernail fragment recovered from the scene of a violent homicide in 1983. A partial STR profile and mtDNA sequence information indicated that the fingernail fragment was excluded as originating from the suspect and was, in fact, consistent with originating from one of the victims.

DNA↗

PubMed2000

[Investigation of the urinary tract in children in nuclear medicine].

The early detection of urologic abnormalities by antenatal sonography has resulted in the investigation of many infants and neonates for suspicion of either obstructive uropathy or reflux nephropathy. Nuclear medicine techniques allow to assess renal parenchyma integrity, to detect pyelonephritic scars and to measure absolute and relative renal function; these methods are easy to perform and reproducible, without any sedation, repeated venous punctures or bladder catheterization. Furthermore, the use of dynamic tubular tracers and frusemide test is a very usefull method which can differentiate between upper and/or lower urinary tract obstruction and determine the degree of obstruction (severe or incomplete) in order to plan for surgery or conservative treatment. The detection of vesicoureteric reflux may be difficult as it is an intermittent phenomenon: the use of the indirect radionuclide cystography (IRC), that is to say after completion of a dynamic renography, allows to detect reflux with a high sensitivity because images can be recorded continuously until the child voids, without any bladder catheterization and at low radiation dosis. In case of discordant results between micturating cysto-urethrography and IRC or of concomittant obstructive uropathy, the direct radionuclide cystography (DRC) is indicated for appropriate treatment. Nuclear medicine techniques do not give morphological information about the urinary tract and should be considered as complementary to radiological investigations in first evaluation of children with recurrent urinary tract infections or hydronephrosis.

Age Factors↗

PubMedDate not supplied

Determination of metals in foods by atomic absorption spectrometry after dry ashing: NMKL Collaborative Study.

A method for determination of lead, cadmium, zinc, copper, and iron in foods by atomic absorption spectrometry (AAS) after dry ashing at 450 degrees C was collaboratively studied in 16 laboratories. The study was preceded by a practice round of familiarization samples and another round in which solutions were distributed and the metals were determined directly by AAS. The study included 5 different foods (liver paste, apple sauce, minced fish, wheat bran, and milk powder) and 2 simulated diets. A single analysis was carried out with each sample. Suitable sample combinations were used as split-level combinations for determination of the repeatability standard deviation. The reproducibility relative standard deviation for each of the elements ranged from 20 to 50% for lead concentrations of 0.040-0.25 mg/kg, from 12 to 352% for cadmium concentrations of 0.001-0.51 mg/kg, from 4 to 8% for zinc concentrations of 0.7-38 mg/kg, from 7 to 45% for copper concentrations of 0.51-45 mg/kg, and from 11 to 14% for iron concentrations of 4-216 mg/kg.

Electrodes↗

PubMed1975

Effect of sulphur dioxide on tracheobronchial clearance at rest and during exercise.

Exposure to pollutants may cause injurious effects by impairing mucociliary transport, one of the lung's most important defences. We have studied the effect of sulphur dioxide (SO2) on tracheobronchial clearance (a) at rest and (b) while exercising, by monitoring lung retention of an inhaled radio-aerosol. Clearance was measured in two sets of conditions. 99mTc-albumen aerosol was inhaled as a bolus in late inspiration under controlled conditions to achieve reproducible deposition in large airways. The studies showed: (1) Clearance was highly reproducible in individuals in repeat control studies. (2) Acute exposure to 5 ppm SO2 showed a small transient speeding of mucociliary clearance at rest. (3) (i) Exercise alone speeded clearance significantly (P less than 0.05). (ii) Exercising in 5 ppm SO2 showed a significant speeding of clearance (P less than 0.05) beyond that found in air breathing exercise controls. (4) Pulmonary function tests showed no significant change except a decrease in flow rate (MMEF) in both (a) and (b) studies (P less than 0.01).

Adult↗

PubMedDate not supplied

In vitro study of laser diode 655 nm diagnosis of occlusal caries.

The aim of this in vitro study was to evaluate the performance of a new laser method (DIAGNOdent, KaVo) by comparing it to the visual inspection, conventional bitewing radiography and digital bitewing radiography. Fifty fresh permanent teeth with clinically sound or suspicious fissures were selected. The teeth were submitted to the diagnostic tests by 2 examiners independently after calibration. The laser examination was repeated to assess the reproducibility. The teeth were sectioned right in the spot that showed the highest value by the laser device. Histological examination of sections (40x magnification) served as gold standard. The results showed that: 1) the intra and interobserver agreement for the DIAGNOdent was excellent (values over 0.87); 2) the sensitivity, specificity and predictive values were very high; 3) and the Spearman correlation coefficient of DIAGNOdent was the best one (R = 0.81), followed by visual inspection (R = 0.68).

Dental Caries↗

PubMed2003

Quantitative assessment of gustatory function in a clinical context using impregnated "taste strips".

Assessment of gustatory sensitivity in a clinical setting is the prerequisite for correct diagnosis and adequate treatment of taste dysfunction. Despite of this, no taste test has been established for the routine clinical testing. The aim of the present study was to create a protocol which is easy to administer. The presently used technique is based on strips made from filter paper which were impregnated with different taste solutions (four concentrations each for sweet, sour, salty and bitter). These strips are placed on the tongue and subjects are asked to identify the taste quality. After establishing the concentration range of the taste solutions, the test was tried in 69 subjects. Each subject received eighteen taste strips (four concentrations of each taste quality plus two blanks) in a pseudo-randomized sequence. Results from this new procedure correlated significantly with the results of the well established extensive three-drop-technique (r69 = 0.67). Repeated measures indicated good reproducibility of the results for the taste strips (r69 = 0.68). These data suggest the usefulness of this new technique in routine clinical practice. Major advantages are long shelf-life, convenience of administration, short time needed for testing (approximately 8 min), and the possibility to test each side of the tongue separately.

Adolescent↗

PubMed2003

Rapid genotyping of haemostatic gene polymorphisms using the 5' nuclease assay.

Hemostatic gene polymorphisms have been shown to be associated with arterial and venous thrombotic disease. To date these polymorphisms have mainly been detected by labor-intensive conventional gel based methods. Aim of the present study was to design and optimize high throughput 5' nuclease assays for the detection of a set of 10 single-nucleotide polymorphisms (SNP) in genes of importance for hemostasis: plasminogen activator inhibitor type 1 -675 4G>5G, thrombin activatable fibrinolysis inhibitor Ala147Thr and 1,542C>G, beta-fibrinogen -455G>A, von Willebrand factor -1,051A>G, factor VII Arg353Gln, factor XIII Val34Leu, prothrombin 20,210G>A, tissue factor pathway inhibitor -287T>C, and methylenetetrahydrofolate reductase 1,298A>C. Specificity of each genotyping assay was confirmed by sequence-based typing and reproducibility was evaluated by repeated genotyping. The genotyping protocols presented here may serve as a valuable tool for clinical researchers interested in exploring associations between these SNPs and thrombotic disease.

Blood Coagulation Factors↗

PubMed1992

[Determination of differential renal function using 99m Tc-DMSA scintigraphy].

By examination of 331 patients, using 99mTc-DMSA, the authors confirmed that static scintigraphy is an accurate method for assessment of the separate renal function. In four groups of patients with different positions of the kidneys the authors proved that correction for different absorption of gamma radiation from the left and right kidney is essential. Without correction results with a significant error are obtained, in particular in patients with an asymmetric position of the kidneys, where the results calculated without correction cannot be used for clinical purposes. The results are not influenced by the time interval between administration of the radiopharmaceutical preparation and examinations within an interval of 2 to 4 hours, with the exception of patients with severe obstructive uropathy. For assessment of the relative function of the kidneys it is better to examine the patient in a vertical position. The reproducibility of results in repeated examinations and repeated evaluation is excellent.

Humans↗

PubMedDate not supplied

A recombinant yeast strain as a short term bioassay to assess estrogen-like activity of xenobiotics.

The study investigated the responsiveness of a recombinant Saccharomyces cerevisiae yeast strain to screen estrogen-like chemicals in order to use it as a first level short-term bioassay for environmental preventive medicine purposes. We used the yeast strain RMY326 ER-ERE, containing the human estrogen receptor alpha and a reporter gene lacZ encoding the enzyme b-galactosidase. We tested the natural steroid hormone 17beta-estradiol, diethylstilbestrol, colchicine, some phytoestrogens and pesticides, and organochlorine insecticides. The relative inductive efficiency (RIE) and EC50 values confirmed the sensitivity and specificity of the yeast strain. A statistically significant reproducibility of results in repeated experiments was assessed.

Biological Assay↗

PubMedDate not supplied

Experimental evaluation of different precision criteria applicable to microbiological counting methods.

The dispersion of microbiological counting measurements, when repeating the analysis on the same material both within a laboratory (repeatability) and between laboratories (reproducibility) can be characterized by the organization of interlaboratory studies, where several sets of identical test materials are sent to several laboratories. Using the example of data generated by an interlaboratory study on enumeration of Listeria monocytogenes in foods by the standardized reference method (colony-count technique), 2 types of robust estimators of reproducibility standard deviations, based on the median, were examined, in comparison with the classical estimators, based on the mean. Experimental evaluation indicated that the 3 approaches gave consistent results for most of the combinations. The usual log10 transformation of the enumeration results was also questioned before these calculations were conducted.

Algorithms↗

PubMedDate not supplied

[Adaptation of Biomerieux enzymatic UV ammonia on Konelab analysers].

INTRODUCTION: Circulating ammonia in normal patients is relatively low, despite the fact that ammonia is continually produced from endogenous amino acid metabolism. The physiopathological interest of plasmatic ammonia determination lies primarily in its relationships to hepatic insufficiency (cirrhotic or neoplasic), or the diagnosis and the forecast of the Reye's syndrome. OBJECTS: This study describes an evaluation of plasmatic ammonia determination by the UV end point enzymatic method using GLDH on KONELAB(TM) analyzers. METHODS: The glutamate dehydrogenase (GLDH : EC.1.4.1.3) catalyses the reducing amination of alpha-cetoglutarate in the presence of NH(4)(+) and of NADPH, H(+) to form glutamate and NADP(+). The reduction of NADPH,H(+)'s concentration, directly proportional to ammonia rates, is evaluated at 340 nm. All the conditions were met to optimize the method, while covering a satisfying field of measurement. RESULTS AND COMMENTS: The evaluation of the modified method showed a good precision (repeatability: CV < 4 %; interserial reproducibility: CV from 2.01 to 2.93 %; Intraserial reproducibility: CV equal to 0.67%) and a very good accuracy. The field of measurement extends from 27 to 250 micromol/L, with a limit of detection (L(D)) lowered to 0.325 micromol/L. CONCLUSION: The adapted technique is simple, fast, inexpensive and especially automatizable. It is in addition reliable and chiefly more sensitive, adapting particularly to the determination of plasmatic ammonia in urgency as in routine within our laboratory.

Ammonia↗

PubMedDate not supplied

Determination of the moisture content of instant noodles: interlaboratory study.

Determination of the moisture content of instant noodles, currently under discussion by the Codex Alimentarius Commission (CAC) requires 2 methods: one for fried noodles and the other for nonfried noodles. The method to determine the moisture content of fried noodles by drying at 105 degrees C for 2 h used in the Japanese Agricultural Standard (JAS) system of Japan can be applied to this purpose. In the present study, the JAS method for fried noodles was modified to be suitable for nonfried noodles by extending the drying time to 4 h. An interlaboratory study was conducted to evaluate interlaboratory performance statistics for these 2 methods. Ten participating laboratories each analyzed 5 test materials of fried and nonfried noodles as blind duplicates. After removal of outliers statistically, the repeatability (RSDr) and the reproducibility (RSD(R)) of these methods were 1.6-2.6 and 3.9-4.8% for fried noodles, and 0.3-1.5 and 1.3-2.9% for nonfried noodles, respectively.

Cooking↗

PubMedDate not supplied

Liquid chromatographic determination of pentaerythritol tetranitrate in pharmaceuticals: collaborative study.

A liquid chromatographic (LC) method for the determination of pentaerythritol tetranitrate (PETN) in pharmaceutical formulations and the bulk drug triturate was evaluated in an interlaboratory study that included 12 participating laboratories. The procedure involves extraction of the active ingredient with mobile phase, followed by filtration of the extract and reverse-phase liquid chromatography using an octadecylsiliane bonded phase column and UV detection at 230 nm. The mobile phase composition is 35% water in acetonitrile (v/v). Three bulk drug samples (20, 20, and 35% PETN), 2 commercial tablet formulations (20 and 80 mg PETN/tablet), and 1 commercial capsule formulation (45 mg PETN/capsule) were analyzed in duplicate by the proposed method. Repeatability (sr, RSDr) and reproducibility (SR, RSDR) based on peak height measurement for these samples ranged from 0.0066 to 0.1806 (0.53-3.36%) and 0.0165 to 0.2075 (0.76-3.86%), respectively. Results for peak area measurements ranged from 0.0145 to 0.2011 (0.93-3.74%) and 0.0231 to 0.2091 (1.28-3.89%), respectively. The method has been approved interim official first action by AOAC.

Capsules↗

PubMedDate not supplied

Methods of analysis for toxic elements in food products. 2. Review of USSR standards on determinations of heavy metals and arsenic.

Methods of analysis prescribed by USSR standards for Hg, Pb, Zn, As, Cd, Cu, Fe, and Sn in foods are described: for Hg--colorimetry of tetraiodide mercurate and atomic absorption spectroscopy (AAS); for Pb, Cd, Zn, and Cu--polarography; for Cu--colorimetry with sodium diethyldithiocarbamate and zinc dibenzyldithiocarbamate; for As--colorimetry with silver diethyldithiocarbamate; for Sn--colorimetry with quercetin; and for Fe--colorimetry with o-phenanthroline. All of the methods have the necessary metrological characteristics, including intralaboratory repeatability value (r), interlaboratory reproducibility value (R), minimum quantity of the element to be determined in the analytical test portion (MQSM), and the coefficients that account for mercury and arsenic losses during analysis. Establishing constant r- and R-values for the methods under consideration is expedient because (a) the methods suggested are used for safety purposes; and (b) the optimum amount of the element studied in the test sample is determined, to a certain degree, by the mass of the test portion.

Arsenic↗

PubMed1985

An experimental model for predicting the synergism of hyperthermia with cytostatics.

A simple prediction test for a combination of hyperthermia and chemotherapy checked on three experimental tumors and cells of the normal murine thymus is described. The testing procedure is based on checking the incorporation of labeled 125I 5-iodo-2-deoxyuridine into the DNA of tested cells affected solely by the enhanced temperature or by the cytostatic itself, or by a combination of both agents. The statistical analysis of repeated results demonstrated the reproducibility of the test. Testing of the potentiation effect of different non-cytostatic substances with enhanced temperatures also gave results corresponding to findings of other authors, performed in vivo or by the use of other techniques. Thus, this simple method is recommended for a screening, before considering the individual use of the combination of hyperthermia and chemotherapy in patients.

Animals↗

PubMedDate not supplied

Automated methods for determination of fat and moisture in meat and poultry products: collaborative study.

A collaborative study was conducted to compare automated methods for rapid determination of fat and moisture in meat and poultry products with the official AOAC solvent extraction and forced-air oven methods, respectively. Fourteen products were tested, with fat and moisture contents ranging from 2 to 43% and 44 to 74%, respectively. Eight of the collaborating laboratories analyzed the products by using a moisture/fat analyzer; 4 laboratories used the AOAC methods. Standard deviations for within-laboratory repeatability, between-laboratory reproducibility, and bias for each product indicated that the rapid methods were acceptable. The moisture/fat analyzer methods have been adopted official first action for fat and moisture analyses in meat and poultry products.

Animals↗