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Results for “Repeatability and Reproducibility”

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At least 1,099 records · Page 61Linked to original sources

PubMedDate not supplied

Enumeration of probiotic pediococci in animal feed: interlaboratory study.

An enumeration method to be used as official control under Council Directive 70/524/EEC for probiotic pediococci used as feed additives was validated for consideration for adoption as Comitée Européen de Normalisation (CEN) and ISO standards. Seventeen laboratories in 11 European countries carried out an interlaboratory study. A spread plate method following BS ISO 15214:1998 using 4 different agars [MRS, acidified MRS, MRS with triphenyl tetrazolium chloride (TTC), and a newly developed pediococci selective medium (PSM)] was validated. Precision data in terms of repeatability (r) and reproducibility (R) of the method for each medium using different feeding stuffs with a high and a low inoculation level were determined. Pediococci were present in the samples in mixtures with other probiotics. The enumeration of pediococci on all agars showed an RSDr value of 0.4-3.1% and an RSDR of 1.3-4.8%. MRS agar was preferred, followed by acidified MRS and MRS + TTC agar. All 4 media gave similar counts. Depending on the presence and concentration of other probiotic, such as enterococci, lactobacilli, and yeast, acidified MRS or MRS + TTC agar are recommended. The PSM was selective for pediococci and can be used if this species is present at a concentration more than 10-fold lower than other species that can grow on the MRS agars. The methodology with all 4 media is not applicable to mineral feed.

Agar↗

PubMedDate not supplied

Multicenter validation of PCR-based method for detection of Salmonella in chicken and pig samples.

As part of a standardization project, an interlaboratory trial including 15 laboratories from 13 European countries was conducted to evaluate the performance of a noproprietary polymerase chain reaction (PCR)-based method for the detection of Salmonella on artificially contaminated chicken rinse and pig swab samples. The 3 levels were 1-10, 10-100, and 100-1000 colony-forming units (CFU)/100 mL. Sample preparations, including inoculation and pre-enrichment in buffered peptone water (BPW), were performed centrally in a German laboratory; the pre-PCR sample preparation (by a resin-based method) and PCR assay (gel electrophoresis detection) were performed by the receiving laboratories. Aliquots of BPW enrichment cultures were sent to the participants, who analyzed them using a thermal lysis procedure followed by a validated Salmonella-specific PCR assay. The results were reported as negative or positive. Outlier results caused, for example, by gross departures from the experimental protocol, were omitted from the analysis. For both the chicken rinse and the pig swab samples, the diagnostic sensitivity was 100%, with 100% accordance (repeatability) and concordance (reproducibility). The diagnostic specificity was 80.1% (with 85.7% accordance and 67.5% concordance) for chicken rinse, and 91.7% (with 100% accordance and 83.3% concordance) for pig swab. Thus, the interlaboratory variation due to personnel, reagents, thermal cyclers, etc., did not affect the performance of the method, which will be proposed as part of a developing international PCR standard.

Animals↗

PubMed2004

Interlaboratory comparison of olfactometry in Japan.

In 2000, 2001, and 2002, interlaboratory comparison of olfactometry was carried out in order to collect basic data for the establishment of a quality control procedure and the determination of quality criteria for the triangular odour bag method. In 2000, interlaboratory comparison was conducted by using a measurement method for samples taken at smoke stacks. On the other hand, the measurement method for samples taken at boundary lines was used for interlaboratory comparison in 2001. A total of seven olfactometry laboratories in Japan participated in each test, and mean values, repeatability standard deviations, reproducibility standard deviations, and standard deviations under intermediate conditions of detection threshold of ethyl acetate were calculated from the results. These values can be used in a quality control process of olfactometry. In 2002, interlaboratory comparison was carried out by using a measurement method for samples taken at smoke stacks. A total of 137 olfactometry laboratories in Japan participated in the test, and 69% of them lay within the permissible range of the odour index.

Air Pollutants↗

PubMed2006

[Preparation of uniform-sized chitosan microspheres and application as carriers for protein drugs].

Chitosan microsphere has been wildly researched in controlled release of protein and peptide drug because of its excellent mucoadhesive and permeation enhancing effect across the biological surfaces. The control of the size and size distribution of microspheres is necessary in order to improve reproducibility, bioavailability, and repeatable release behavior. In this work, uniform-sized chitosan microspheres containing insulin were prepared by a novel membrane emulsification technique combined with glutaraldehyde crosslinking method. In order to prepare uniform-sized chitosn microspheres, it is necessary to modify hydrophilic membrane into hydrophobicity. It is found that there exists a linear relationship between the size of chitosan microspheres and pore size of the membrane used, so it is easy to control the size of microspheres by using membranes with different pore size. In this study, the effect of different amount of crosslinker and crosslinking time on microspheres' morphology, encapsulation efficiency (EE) and release profile of drug in vitro were investigated. It is shown that the morphology of microspheres is more smooth and spherical, and the release rate is slower with the increase of amount of glutaraldehyde and prolongation of crosslinking time. When the molar ratio of amino group of chitosan to aldehyde group of glutaraldehyde is 1:0.7, and crosslinking time is 1 h, the highest EE was obtained (about 65%). Date obtained suggest that chitosan microspheres prepared by this new method would be a promising system for controlled release of protein drugs.

Biocompatible Materials↗

PubMed1976

[Experimental reproduction of necrotic enteritis in the chicken. 2. Further mono- and polyinfections with CL. perfringens and coccidia with special reference to ground-kept chickens].

Coccidial oocysts and/or vegetative germs, spores, and toxins of Cl. perfringens Type A were used in mono-infection and poly-infection experiments on SPF chicken aged seven and 56 days and kept under different conditions. Necrotic enteritis was regularly reproduced in all experimental groups with polyinfections. In chicken aged seven days necrotic enteritis was reproduced even after repeated mono-infections with 4 X 10(9) gerus and toxin of Cl. perfringens. The loss figures recorded from ground-kept infected groups were higher than those established from the cage-kept animals. The pathologica-anatomic findings recorded from the dead chicken included necrotic, ulcerative, and catarrhal to haemorrhagic intestinal inflammations, with necrotic enteritis being most strongly pronounced in the ileum and jejunum. All infected groups lost not only animals but weight as well. Their average weight on the 21 st day from the onset of infection was up to 26.4 per cent lower than that of the control groups.

Animals↗

PubMedDate not supplied

Sulfuric acid/hydrogen peroxide digestion and colorimetric a collaborative study.

Seven laboratories participated in a collaborative study of a method for determination of phosphorus in meat and meat products. Samples are digested in sulfuric acid and hydrogen peroxide; digestion is complete in approximately 10 min. Phosphorus is determined by colorimetric analysis of a dilute aliquot of the sample digest. The collaborators analyzed 3 sets of blind duplicate samples from each of 6 classes of meat (U.S. Department of Agriculture classifications): smoked ham, water-added ham, canned ham, pork sausage, cooked sausage, and hamburger. The calibration curve was linear over the range of standard solutions prepared (phosphorus levels from 0.05 to 1.00%); levels in the collaborative study samples ranged from 0.10 to 0.30%. Standard deviations for repeatability (sr) and reproducibility (SR) ranged from 0.004 to 0.012 and 0.007 to 0.014, respectively. Corresponding relative standard deviations (RSDr and RSDR, respectively) ranged from 1.70 to 7.28% and 3.50 to 9.87%. Six laboratories analyzed samples by both the proposed method and AOAC method 24.016 (14th Ed.). One laboratory reported results by the proposed method only. Statistical evaluations indicated no significant difference between the 2 methods. The method has been adopted official first action by AOAC.

Animals↗

PubMed1991

[High resolution electrocardiogram and late potential monitoring].

The signal-averaged ECG became an important noninvasive method for identifying life-threatening ventricular arrhythmias. It is most accurate in patients with coronary artery disease and can be helpful in predicting whether a patient with an unexplained syncope or nonsustained VT is at risk of developing sustained ventricular tachycardia or not. A patient with an entirely normal signal-averaged ECG is at very low risk of sustained VT. In contrast, an abnormal signal-averaged ECG should raise suspicion about VT, and prompt further studies, including electrophysiological testing. Signal-averaged ECG can also be used repeatedly with acceptable reproducibility. Technological advances and improvements in the frequency analysis of the averaged signal may increase the predictive accuracy of the technique and consequently enhance its clinical applications.

Electrocardiography↗

PubMed1990

Local treatment of spasmodic torticollis with botulinum toxin.

Fifteen patients with spasmodic torticollis were treated with local injections of botulinum--A toxin. All the patients were followed for a period of 4 to 7 months. Thirteen out of 15 patients (86%) improved in the amount of sustained movements of torticollis. In six out of 9 patients presenting with pain complete relief was noted. Beneficial effects of botulinum toxin injections lasted from 2 to 3 months, with reproducible efficacy after repeated injections. The most frequent side effect was dysphagia, presented in 10 patients.

Adult↗

PubMedDate not supplied

Precision parameters of methods of analysis required for nutrition labeling. Part I. Major nutrients.

Major components of foods and feeds are fat, protein, and carbohydrates. Fat and protein are determined by direct measurements that are interpreted as the quantity of the constituent. Carbohydrates are usually calculated by difference. For this calculation, values for moisture/solids, ash, and "fiber" are also needed. The readily available collaborative studies for the determination of these major components are reviewed in an attempt to assign precision parameters to validated methods of analysis. When a number of studies for the same analyte, in the same food, by the same method are available, it is seen that the precision parameters among laboratories (standard deviations, SR; relative standard deviations, RSDR) and the ISO maximum tolerable difference functions (repeatability value, r; reproducibility value, R) are not characterized by any conventional distribution. The precision data are best summarized as a median or average parameter and the interval containing the centermost 90% of reported values. Typically, the precision of methods of analysis can be expressed as a function of concentration only, independent of analyte, matrix, and method. The average RSDR value from each collaborative data set can then be used as the numerator in a ratio containing, as the denominator, the value calculated from the Horwitz equation: RSDR = 2 exp (1 - 0.5 log C) where C is the concentration as a decimal fraction. A series of ratios consistently above 1, and especially above 2, probably indicates that a method is unacceptable with respect to precision. By this criterion, only the protein (Kjeldahl) determination is unqualifiedly acceptable with a 90% interval for RSDR of 1 to 3% at C values above about 0.01 (1 g/100 g). Fat, moisture/solids, and ash are acceptable down to limiting concentrations in the region of 1 to 5 g/100 g, if a test portion large enough to provide at least 50 mg of weighable residue or volatiles is specified. Measurements of individual carbohydrates and fiber-related analytes have unexpectedly poor precisions among laboratories. The variability, although high, may still be suitable for nutrition labeling. Reliability of analyses for the control of labeling of the primary nutrients must be achieved through quality assurance programs that require strict adherence to the directions of empirical methods and the use of suitable reference materials for absolute methods.

Databases, Bibliographic↗

PubMed1990

Synergistic potentiation of in vivo antitumor activity of anti-human T-leukemia immunotoxins by recombinant alpha-interferon and daunorubicin.

In the present study, immunotoxins (ITs) containing ricin A chain (RA) and anti-human T leukemia monoclonal antibodies SN1 and SN2 were used with or without alpha-interferon (IFN) and/or daunorubicin (DNR) for in vivo tumor suppression. SN1 and SN2 are directed toward two unique human T-leukemia-associated cell surface antigens, TALLA and GP37, respectively. As the tumor model, we used nude mice bearing ascitic tumors of Ichikawa, a human T acute lymphoblastic leukemia cell line. In initial studies, we investigated the effect of the IT injection schedule on the efficacy of ITs in the in vivo suppression of the ascitic tumors. Four doses of 20 micrograms each of SN1-RA and SN2-RA completely suppress the tumor growth in 100% of the treated mice when the IT treatment is initiated either 1 or 2 days after tumor inoculation of 1.6 x 10(7) Ichikawa cells into the mice. Subsequently, we investigated the potentiating effects of IFN and DNR on the in vivo antitumor activity of ITs. To this end, we chose to initiate the treatment 4 days after the tumor inoculation when IT treatment alone is only partially effective. ITs (10 micrograms each of SN1-RA and SN2-RA) plus IFN (2 x 10(5) IU) or ITs plus IFN plus DNR (5 micrograms) completely suppress tumor growth in 100% of the treated mice while similar treatment with any one of the three agents is only partially effective. Similar treatment with ITs plus DNR or IFN plus DNR results in complete suppression of tumor growth in 80% of the treated mice. These results were reproducible in a repeated experiment. To gain information about the mechanisms involving the IFN potentiation of IT activity, we carried out several experiments. The cell surface expression of TALLA and GP37 was slightly augmented by the in vitro incubation of Ichikawa cells with IFN as measured by fluorescence-activated cell sorter analysis. The degree of the increase in either TALLA or GP37 was significantly smaller than that of HLA class I antigens in the same experiment. In in vitro experiments, IFN did not show any significant cytotoxic activity against Ichikawa cells or augment the cytotoxic activity of ITs against Ichikawa cells. On the other hand, injections of IFN into nude mice augmented activity of macrophages and NK cells; however, Ichikawa leukemia cells were rather resistant to the NK cell lysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMedDate not supplied

Gas chromatographic assay of supplemental vitamin E acetate concentrates: collaborative study.

A gas chromatographic (GC) method for determination of supplemental alpha-tocopheryl acetate in high potency vitamin E powders and oils was collaboratively studied as an alternative to the AOAC colorimetric method (43.147-43.151, Emmerie-Engel), which requires saponification, extraction of the saponifiable fraction, and quantitation by colorimetry. The simpler GC procedure requires only extraction and/or enzymatic digestion and dilution before quantitation. Six blind duplicates were distributed to 10 laboratories; all 10 returned results. Repeatability (sr) and reproducibility (sR), % vitamin E/g, for the feed oil concentrates was 1.1 and 1.3, respectively; for the feed adsorbates 1.0 and 1.5; and for the spray-formulated powders 1.4 and 1.3. These results compare favorably with results obtained in a comparison study of the GC and Emmerie-Engel methods conducted by BASF in 1985. The method has been approved interim official first action for determination of alpha-tocopheryl acetate in vitamin E acetate concentrates as an alternative for those products only to AOAC colorimetric method 43.147-43.151.

Chromatography, Gas↗

PubMed1987

Quantitative determination of cyclosporin A in whole blood and plasma by high performance liquid chromatography.

A simple, specific and sensitive method for monitoring therapeutic levels of the immunosuppressive agent cyclosporin A (CyA) in whole blood and plasma has been developed which uses a high performance liquid chromatography and involves a simple liquid-liquid extraction procedure. Samples were delipolysed with 0.1 mM dextran sulfate sodium salt, extracted with n-hexane, and chromatographed on a Lichrosorb Si-60 column with UV detection at 215 nm. Each of CyA and internal standard (cyclosporin D) is resoluted clearly as a single peak and no interfering peaks are observed on the chromatograms. The detection limit is 5 ng/ml in whole blood and plasma. The reproducibility assessed by repeated analysis is satisfactory, that is to say, each coefficient of variation of the within-run and between-run precision is below 4%. The analytical recovery of added CyA is almost complete. This method is sensitive enough for monitoring whole blood and plasma levels of CyA in renal transplant patients in the therapeutic dose range, and is also applicable to the study on the distribution of CyA between plasma and non-plasma fractions of blood in patients with renal allografts.

Adolescent↗

PubMed1988

Purification of anti-apolipoprotein CIII antibodies by exploiting their affinity for apolipoprotein CIII linked to polyacrylamide gel after isoelectric focusing.

A new immunoaffinity technique for purifying anti-apolipoprotein CIII antibodies has been developed by isolating bands of apo CIII2 from isoelectric focusing (IEF) gel. Total apo C was obtained from delipidated very-low-density lipoprotein by chromatography on Sephacryl S 200. Apo CIII2 was separated from the apo CII band by IEF on polyacrylamide gel with use of pH 4-6 ampholytes. After sonication of the band in distilled water and various different washes, we directly mixed with antiserum a suspension of apo CIII2 bound to IEF-polyacrylamide gel. After their elution, we tested the specificity of the antibodies by an enzyme immunoassay technique, using plates coated with apolipoprotein, 100 ng per well. No cross-contamination of eluted anti-apo CIII antibodies by anti-apo CII or anti-apo E antibodies was observed. This affinity technique is easy to use, rapid to perform, and no sophisticated apparatus is needed. The gels can be used repeatedly and yield reproducible results with a very good analytical recovery (94%). We anticipate that this technique will prove useful for purification of other antibodies, particularly antibodies to apolipoproteins such as anti-apo CII and anti-apo E.

Acrylic Resins↗

PubMed1978

Environmentally triggered cardiac disease.

Twelve highly selected patients with non-arteriosclerotic cardiac arrhythmias and/or chest pain refractory to medication and having symptoms related to smooth muscle sensitization were studied in a rigidly controlled, relatively fume- and particle-free environment. The majority of signs and symptoms cleared in 10 patients without medication while under environmental control, and in 10 of the 12 patients all arrhythmias were reproduced with controlled, repeated individual-blind and double-blind incitant challenges. Blood abnormalities occurred in the complement and T-lymphocyte systems.

Adolescent↗

PubMed1986

Gated xenon scans for right ventricular function.

The complex geometry of the right ventricle makes the use of radionuclides an attractive method for assessing right ventricular function. The use of the gated 133Xe technique for this purpose offers several advantages. A short i.v. infusion over 20 sec of 133Xe permits scans to be obtained, gated to the electrocardiogram at rest and during maximal exercise using a standard gamma camera. The method is both reproducible (3.5%) and repeatable (2.8%), and because of the short half-life within the patient with most of the radioisotope being excreted by the lungs, scans may be repeated within a few minutes and the radiation dose to the patient is small. Right ventricular ejection fraction obtained from gated xenon scans is shown to correlate well with measurements obtained from both standard gated technetium scans and first-pass studies.

Female↗

PubMed1985

Rapid measurement of free anticonvulsant drugs by direct liquid chromatography of serum ultrafiltrates.

In this simultaneous assay of unbound phenobarbital, phenytoin, primidone, and carbamazepine, serum ultrafiltrate is prepared by centrifugation in disposable filter units (Centrifree Micropartition System, Amicon Corp.) and injected directly onto a reversed-phase liquid-chromatography column. Drugs in the effluent are detected by absorbance at 210 nm. The measured concentrations were not critically dependent on the exact conditions of ultrafiltration (rotor angle, speed or time of centrifugation, amount of sample filtered). Pooled serum containing all four drugs gave reproducible results in repeated analyses during several days. For comparison we assayed 113 clinical specimens for one or more of these drugs by this method, and for the total (bound plus unbound) concentration of each drug by immunoassay. For each drug there was a nearly linear relationship between the two types of measurements, except for six specimens that had unusually high fractions of unbound drug. This assay appears highly suitable for routine determination of the free, biologically active fraction of anticonvulsant drugs, possibly as an alternative to measurements of total drug concentrations.

Anticonvulsants↗

PubMed1985

The book availability study as an objective measure of performance in a health sciences library.

In its search for an objective overall diagnostic evaluation, the University of Illinois Library of the Health Sciences' Program Evaluation Committee selected a book availability measure; it is easy to administer and repeat, results are reproducible, and comparable data exist for other academic and health sciences libraries. The study followed the standard methodology in the literature with minor modifications. Patrons searching for particular books were asked to record item(s) needed and the outcome of the search. Library staff members then determined the reasons for failures in obtaining desired items. The results of the study are five performance scores. The first four represent the percentage probability of a library's operating with ideal effectiveness; the last provides an overall performance score. The scores of the Library of the Health Sciences demonstrated no unusual availability problems. The study was easy to implement and provided meaningful, quantitative, and objective data.

Books↗

PubMed1969

[Biochemical study of the genital secretions of sterile bovine females presenting normal estrus cycles].

Exocervical samplings of 57 cows' genital secretions (30 normal reproducing and 27 repeat breeder cows) were studied during estrus. An attempt has been made to detect the following electrolytes: A1, Ca, Co, Cu, Fe, K, Mg, Mn, Na and Zn in these secretions. Ca, K, Mg and Na were found. No significant difference is noted in the Ca, K and Mg concentration (P>0.05) between the two groups, whereas a highly significant difference (P<0.001) in exocervical Na concentration has been measured between these groups.

Animals↗