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Results for “Repeatability and Reproducibility”

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At least 829 records · Page 46Linked to original sources

PubMedDate not supplied

[Characteristics of food anaphylactic reactions to proteins and protein preparations in guinea pigs with different duration of hexenal-induced sleep].

The state of guinea pig sensitization was studied in the direct test in vivo by induction of active food anaphylaxis (FA). The animals were orally sensitized with food allergens: chick ovalbumin (OVA), bovine serum albumin, and protein preparations N 1 and N 2 (PP N 1 and N 2). In guinea pigs with null hexenal-induced sleep (NHS) and long hexenal-induced sleep (LHS), 40 min, the duration of HS is reliably reproduced in repeated testing. The intensity of FA reactions in guinea pigs with NHS was less manifested than in the animals with LHS with both food allergens. Significantly higher allergenic properties of PP N 2 were expressed in the animals with LHS. It was shown that varying anaphylactic sensitivity of guinea pigs in the above groups was not related with different permeability of the gastrointestinal tract of these animals for OVA macromolecules. Possibilities of metabolic validation of increasing anaphylactic sensitivity of guinea pigs with LHS have been considered.

Anaphylaxis↗

PubMed2006

Electroanalytical determination of donepezil HCl in tablets and human serum by differential pulse and osteryoung square wave voltammetry at a glassy carbon electrode.

Donepezil hydrochloride (DNP) is used for the treatment of mild to moderate dementia of the Alzheimer's type. The voltammetric behavior of DNP was studied at a glassy carbon electrode using cyclic, linear sweep, differential pulse (DPV) and square-wave (OSWV) voltammetric techniques. DNP exhibited irreversible anodic waves within the pH range 1.80 and 9.00 in different supporting electrolytes. The peak was characterized as being irreversible and diffusion-controlled. The possible mechanism of the oxidation process is discussed. The current-concentration plot was rectilinear over the range from 1 x 10(-6) to 1 x 10(-4) M in Britton-Robinson buffer at pH 7.0 with a correlation coefficient between 0.997 and 0.999 in supporting electrolyte and human serum samples using the DPV and SWV techniques. The repeatability and reproducibility of the methods for both media (supporting electrolyte and serum sample) were determined. Precision and accuracy of the developed methods were demonstrated by recovery studies. The standard addition method was used for the recovery studies. No electroactive interferences were found in biological fluids from endogenous substances or additives present in tablets. The methods developed were successfully applied to the determination of DNP in tablets and in spiked human serum.

Algorithms↗

PubMed1991

UK external quality assessment scheme for immunoassays in endocrinology.

UK EQAS provide the UK with a comprehensive system for EQA in endocrinology, as well as in other aspects of clinical chemistry and laboratory medicine. UK EQAS in endocrinology are scientifically designed to yield an objective assessment of participants' performance and stimulate improvements in between-laboratory agreement. The design uses appropriate specimens, based on liquid human serum and prepared with minimal processing and additives in the organising centres to enable detailed study of recovery and other important factors. Target values are validated by reproducibility on repeated distribution and by recovery and parallelism studies. Reports are presented informatively, and emphasise the cumulative scoring system (bias and variance) for performance assessment. Computerised data processing and data presentation form an integral part of these schemes, and a common core computing system is in use throughout these UK EQAS. Participants receive advice and assistance in the interpretation of performance data and, when appropriate, in the resolution of problems.

Chemistry, Clinical↗

PubMedDate not supplied

Liquid chromatographic determination of chloramphenicol in calf tissues: studies of stability in muscle, kidney, and liver.

A liquid chromatographic method has been developed for the measurement of chloramphenicol (CAP) in muscle, liver, and kidney. The mean recovery levels were 82.6, 75.3, and 79.2% in muscle, liver, and kidney, respectively. The method was repeatable and reproducible for CAP measurement in muscle, with a detection limit of 1 microgram/kg. Investigation of CAP stability in muscle, liver, and kidney showed that CAP stability in muscle was good at -20 degrees C; for spiked liver and kidney, degradation of CAP was observed, and the use of piperonyl butoxide (PB) for metabolism inhibition was recommended for recovery and linearity studies. However, PB was unnecessary for preservation of treated animal tissues if samples were cut into cubes and cooled at -20 degrees C, just after slaughter, pending analysis. With these limitations, CAP can be measured in liver and kidney.

Animals↗

PubMedDate not supplied

Dry rehydratable film for enumeration of total coliforms and Escherichia coli in foods: collaborative study.

Rehydratable dry-film plating methods for total coliforms and Escherichia coli in foods have been compared to the AOAC most probable number methods. Fourteen laboratories participated in the collaborative study. Three coliform and E. coli levels in 6 samples of 4 product types (flour, nuts, cheese, and beef with gravy) and in 3 samples of 2 product types (mushrooms and raw turkey) were tested in duplicate by the participants. The mean log counts for the 3 methods were comparable. In general, the repeatability and reproducibility variances of the plating methods were as good as or better than that of the MPN method. The method has been adopted official first action by AOAC.

Animals↗

PubMed1978

[Comparative analysis of the action of an interferon inducer in in vitro and in vivo systems].

Investigation of interferon inductor (poly IC) in vitro (chick embryon fibroblasts) and in vivo (mice) showed that the main parameters of the preparation effect, i. e. induction of interferon and development of resistance to viruses are as a whole quite comparable. The phenomenon of hyporeactivity in the both systems was reproduced on repeated use of the inductor. At the same time significant differences in the stimulating effect of DEAE-dextran were registered. The merits and demerits of the in vitro system for using in studies on antiviral drugs of the above type are discussed.

Animals↗

PubMedDate not supplied

Antihypertensive and diuretic effects of NZ-105, a novel dihydropyridine derivative.

Studies on the antihypertensive and diuretic actions of NZ-105, a new dihydropyridine derivative, were performed in comparison with nicardipine. NZ-105 and nicardipine (5, 10 and 20 mg/kg, p.o.) dose-dependently decreased systolic blood pressure in three types of experimentally hypertensive rats, including spontaneously hypertensive rats, renal hypertensive rats and deoxycorticosterone acetate-salt hypertensive rats and normotensive Wistar-strain rats. The hypotensive effects were larger in hypertensive rats than in normotensive Wistar rats. The hypotensive actions of NZ-105 were very slow in onset and long-lasting in all models, e.g., the hypotension by NZ-105 (10 mg/kg, p.o.) reached a peak (-52 mmHg) at 3 hr and lasted for more than 9 hr in spontaneously hypertensive rats. The hypotensive action in spontaneously hypertensive rats was reproducible after repeated dosing twice a day for 29 days. The hypotensive action after i.v. injection of NZ-105 (0.1 mg/kg) in spontaneously hypertensive rats was also slow in onset (peak time: 10 min) and long-lasting (more than 120 min). The hypotensive potency of NZ-105 was about the same as that of nicardipine, but the increment in heart rate was smaller than in the case of nicardipine. Both NZ-105 and nicardipine showed diuretic and natriuretic actions in spontaneously hypertensive rats. After repeated administration, these actions of NZ-105 were unchanged, whereas those of nicardipine were reduced. These results suggest that NZ-105 is a useful antihypertensive drug with concomitant diuretic effects.

Animals↗

PubMedDate not supplied

Colorimetric determination of hydroxyproline as measure of collagen content in meat and meat products: NMKL collaborative study.

A colorimetric method for the determination of hydroxyproline as a measure of collagen in meat and meat products has been collaboratively studied in 18 laboratories. The method includes hydrolysis with sulfuric acid, oxidation with chloramine-T, and formation of a reddish purple complex with 4-dimethylaminobenzaldehyde. Five frozen and 3 freeze-dried samples were tested, ranging in content from 0.11 to 0.88% and from 0.39 to 4.0% hydroxyproline, respectively. The mean values of 2 identical samples were 0.245 and 0.251%. The average recovery from a spiked sample was 96.1%. The hydroxyproline content of a known sample (a mixture of 2 samples in the ratio 5:2) was calculated to 1.42%, which agrees well with the analytical result, 1.40%. In comparison with other collaborative studies, based on the ISO analytical method, the repeatability and reproducibility of this method agree well with the other results. This method was accepted as an official NMKL method by all national Committees, and has been adopted official first action by AOAC as an NMKL-AOAC method.

Animals↗

PubMed1990

[Daunomycin rats. Second Report. Is it possible to use daunomycin rats as an experimental model of chronic renal failure?].

We have previously reported that daunomycin rats can be used as an experimental model of chronic renal failure. We have since studied whether the result were reproducible by repeating the experiment. In this experiment we used larger numbers of rats and many more parameters of investigation compared with the previous experiment. The period of observation was extended to 42 weeks. Twenty-one female Wistar rats were given an injection of 12 mg/Kg of daunomycin into the jugular vein by the one-shot method. Ten control rats were injected with physiological saline. Eighteen daunomycin rats developed chronic renal failure within the observation period. Renal failure was confirmed by the levels of BUN and creatinine, the uremic peak 2a and the pathological findings. One rat died from a tumor and another rat died from thrombosis of the descending aorta. In only one rat was not at the level defined as chronic renal failure, although it was impaired even in this case. There was a correlation between the lifespan of the daunomycin rats and the amount of urine protein at 4 weeks. Rats with heavy proteinuria at 4 weeks died of uremia at an early age. There was a variety of evidence of daunomycin damage when rats were autopsied, not only in the renal glomeruli but also in the pancreas, liver and spleen. Some parts of the pancreas and liver showed vacuolated cells. We supposed that these various changes of many internal organs of daunomycin rats were secondary changes for chronic renal failure. We reconfirmed that daunomycin rats can be used as an experimental model of chronic renal failure.

Animals↗

PubMedDate not supplied

Gas chromatographic determination of nicotine in environmental tobacco smoke: collaborative study.

A gas chromatographic method for determination of vapor phase nicotine in environmental tobacco smoke (ETS) was collaboratively studied by 6 laboratories. Nicotine is desorbed from XAD-4 sample tubes with ethyl acetate containing triethylamine and determined by gas chromatography with nitrogen-selective detection. Each collaborator received blind duplicate samples at each of 6 nicotine concentrations. Three concentrations were generated by spiking XAD-4 tubes with known amounts of nicotine; the remaining 3 concentrations were ETS samples obtained in a carefully controlled environmental chamber containing sidestream and exhaled mainstream smoke from 1R4F Kentucky reference cigarettes. Repeatability and reproducibility relative standard deviations ranged from 4.4 to 11.1% and from 7.0 to 11.1%, respectively, for nicotine concentrations evaluated (up to 6 micrograms/cu m). The method has been adopted official first action.

Chromatography, Gas↗

PubMed1989

Matters relating to tooth sizes in Kenyan and British subjects.

The mesio-distal widths of teeth and the breadth of the dental arches were measured on study casts of twenty young Kenyan African males and twenty young male British adults in Belfast, Northern Ireland. All subjects had normal occlusion. Measurements were repeated for reproducibility testing which proved satisfactory. With the exception of the lower central incisor, all the Kenyan teeth were larger than their Caucasian counterparts, but only the differences relating to the premolar and molar teeth reached the level of statistical significance. The lower arch breadths measured between the first premolars and between the first permanent molars proved significantly greater in the Kenyan group. In the upper arch, the mean premolar breadth was greater but the difference in molar breadth was not statistically significant. This finding relates to the diminished buccal overjet in the Kenyan subject.

Black People↗

PubMed1989

Detection of anti-vascular endothelial cell antibodies with microcytotoxicity testing.

Antivascular endothelial cell antibodies (anti-VEC) were detected in 20 out of 20 serum samples from post renal transplant nephrectomy patients using a microcytotoxicity (MET) test, but in only 1 of 100 healthy blood donors. Cytotoxicity to VEC could occur in the absence of lymphocytotoxic antibodies. In this paper factors influencing the specificity and sensitivity of microcytotoxicity on vascular endothelial cell (VEC) were studied, including improvements in the preparation of VEC from an umbilical cord vein to get 95% and more of purity and viability; adequate dilution of rabbit sera to reduce its nonspecific VEC cytotoxic effect; and results read by exactly adjusted phase contrast microscopy to reduce the percentage of false negative. The original titers of allotypic and monoclonal antibodies against VEC have been shown to be reproducible in repeated testing during the past two years. The recognition of the weak cytotoxic effects of anti-HLA on VEC makes possible direct application of microcytotoxicity on VEC, to detect anti-VEC and to study VEC antigen classification (through a comparison of the cytotoxic effects of tested sera on VEC and concordant lymphocytes).

Antibodies↗

PubMed1977

Spectral analysis of mouse EEG after the administration of N,N-dimethyltryptamine.

Mice were implanted with permanent cortical electrodes. The EEG was recorded during the sleep-wake cycle and after the administration of N,N-dimethyltryptamine (DMT). Based upon spectral analysis the EEG was classified into three categories: awake, slow-wave sleep (SWS), and rapid eye movement sleep (REM). The dominant frequencies were located below 2 Hz in the case of SWS and between 6 and 9 Hz for REM. When DMT was administered intraperitoneally at 20 or 40 mg/kg, a dose-dependent hypersynchrony at 2.5-4.5 Hz was always observed lasting for up to 60 min. Hypersynchronous activity in the same range was occasionally observed during awake. In this range DMT induced a different but unique frequency for each animal. This individual frequency was closely reproduced by repeated administrations of DMT to the same animal.

Animals↗

PubMed1988

Quantitative determination of tumor blood flow and perfusion via deuterium nuclear magnetic resonance spectroscopy in mice.

Murine RIF-1 tumor blood flow and perfusion were quantified by deuterium NMR using D2O as a freely diffusible tracer. After direct intratumor injection of D2O saline solution, the tracer (HOD) residue from the tumor was detected by deuterium NMR and the deuterium residue washout time course was then analyzed employing multicompartment flow models (S-G. Kim and J.J.H. Ackerman, manuscript submitted for publication). The mean tumor blood flow and perfusion rate was 18.5 +/- 8.5 SD ml/(100 g.min) (n = 46) when analyzed by a two-compartment in-series flow model. A number of tumors (n = 15 out of 61 total) showed a biexponential deuterium tracer washout curve. Application of a three-compartment flow model (S-G. Kim and J.J.H. Ackerman, manuscript submitted for publication) fitted the biexponential residue decay data well and yielded a mean tumor blood flow of 15.7 +/- 9.7 SD, fast- and slow-flow components of 36.8 +/- 19.8 SD and 9.7 +/- 5.8 SD ml/(100 g.min), and a fast-flow component fraction of 21 +/- 10 SD%. Small tumors of less than 0.5 cm3 had faster blood flow, 21.1 +/- 8.4 SD ml/(100 g.min) (n = 27), than large tumors of greater than 1.0 cm3, 9.4 +/- 2.9 SD ml/(100 g.min) (n = 13). The NMR measurement of tumor blood flow and perfusion was not dependent on the number of direct intratumor injection sites and was found reproducible upon repeated measurements of individual tumors. Good agreement with previous in situ photon activation H215O flow determinations was observed.

Animals↗

PubMed1988

Measurement of absolute left ventricular volume by radionuclide angiography: a technical review.

Absolute left ventricular volumes have important clinical implications in the evaluation of cardiac performance. Several invasive and noninvasive techniques have been reported, none of which can be considered ideal for this purpose. Contrast angiography, echocardiography and radionuclide ventriculography are open to criticism. Different radioisotopic approaches are described with emphasis on the importance of accurate separation of left ventricular activity, the selection of background activity, and the correction for photon attenuation by body tissues. Improper use of statistics and validation techniques have obscured the value of these techniques. In the absence of a 'gold standard' there should be a 'radioisotopic' left ventricular volume with established independent characteristics, repeatability and reproducibility by which new approaches can be judged.

Cardiac Volume↗

PubMed1988

Action spectrum for UV erythema and reproduction of the skin lesions in hydroa vacciniforme.

Action spectra for UV erythema and reproduction of the skin lesions in 4 patients with hydroa vacciniforme (HV) were studied. Vesicles were successfully reproduced by repeated daily monochromatic irradiations of 330, 340, 350 and 360 nm for 5, 6 or 7 days. The daily doses were equivalent to global solar radiation for 70-190 min. The vesicles produced were identical to those of HV, macroscopically and histologically. Repeated daily exposures to a small dose of UVA produced vesicles, whereas a large but single exposure to UVA failed to do so. Daily exposures to UVB failed to produce the vesicles. The minimal erythema dose (MED) was lower than the minimum limits of the normal persons in the 290-310 nm range.

Adolescent↗

PubMed1988

[Use of an expert system as a tool to carry out urinary cyto-bacteriologic tests].

An expert system for urine examinations was developed. Its validation was performed in a routine work, by comparison of expert decisions with software conclusions. Results of finished examinations or in progress were taken into account. The agreement was satisfactory. In addition to reliability, advantages constituted by availability, flexibility and adaptability were notified. Repeatability and reproducibility were also emphasized.

Algorithms↗

PubMed1977

Collaborative study of a method for the detection of Clostridium botulinum and its toxins in foods.

The mouse toxicity and protection technique for the detection and identification of Clostridium botulinum and its toxins in foods was collaboratively studied by 11 laboratories. Each laboratory received 4 samples of cream of mushroom soup; 2 contained spores and toxin of C. botulinum type A, 1 contained spores and toxin of C. botulinum type E, and 1 contained spores of C. sporogenes. The media used were cooked meat medium (beef heart or chopped liver broth) and trypticase peptone glucose yeast extract broth with trypsin. The results indicate that this method has a high degree of repeatability and reproducibility. All 11 laboratories correctly identified the toxins and the nontoxic sample in the food and detected and identified the viable spores in the samples by means of the subsequent cultures. This method has been adopted as official first action.

Biological Assay↗