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Results for “Repeatability and Reproducibility”

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At least 109 records · Page 6Linked to original sources

PubMed1992

Relationship between nonspecific bronchial responsiveness to methacholine and peripheral mononuclear leukocyte beta-adrenergic receptor function in young drug-naive subjects.

Asthma is associated with dysfunction of the beta-adrenergic receptor adenylyl cyclase signal transduction pathway. It has been argued that this results from receptor down-regulation by beta-agonist therapy. This study examined the relationship between nonspecific bronchial responsiveness (NSBR) to methacholine (Newcastle dosimeter method) and beta-adrenergic receptor density (Bmax) and affinity (%KH) in membranes from peripheral blood mononuclear leukocytes (MNL) in 12 male (27.3 +/- 1.7 yr old) and 14 female (31.4 +/- 1.7 yr old) drug-naive subjects with and without symptoms of mild intermittent wheezing. None had ever smoked or received any antiasthma medication. "Hyperresponsive" subjects were defined as those (n = 11) whose simplified slope of FEF50 (calculated as the percent fall in FEF50 divided by the dose of methacholine) was more than one SD above the mean for asymptomatic subjects. The log of the slope was reproducible (repeatability coefficient = 0.43) on two nonconsecutive days. Multiple regression analysis (overall R2 = 0.57) revealed negative relationships between the log of the slope and both Bmax (p = 0.016) and %KH (p = 0.011). Analysis of variance confirmed a lower mean (+/- SEM) value of %KH in "hyperresponsives" (45.7 +/- 5.5%) than in "normoresponsives" (60.4 +/- 4.1%, p = 0.04) with a similar trend for Bmax (hyperresponsives = 33.5 +/- 4.1 fmol/mg, normoresponsives = 45.9 +/- 7.1 fmol/mg, p = 0.18). These relationships between bronchial responsiveness, Bmax, and %KH cannot be explained by drug therapy, and they provide further evidence that there is an intrinsic impairment in the function of beta-adrenergic receptors on peripheral MNLs from subjects with high levels of nonspecific bronchial responsiveness.

Adolescent↗

PubMedDate not supplied

Controlled release from a large capsule membrane corked with phosphatidylethanolamine bilayers: effect of temperature, pH and concentration of Ca2+ ions.

Permeations of a fluorescent probe entrapped in the inner aqueous phase of a large nylon capsule membrane corked with phosphatidylethanolamine bilayers were reversibly controlled by (i) the phase transition of bilayers, (ii) the ambient pH change, and (iii) the addition of Ca2+/EDTA from outside. Their signal-receptive permeation control could be reproduced repeatedly without damaging corking bilayers, in contrast to that of liposomal membranes.

Calcium↗

PubMed1989

Correlation of tonography and constant pressure perfusion measurements of outflow facility in the rabbit.

The values of aqueous outflow facility, determined using tonography and constant pressure perfusion, were compared in the New Zealand white rabbit. Four-minute indentation tonography was followed by multi-level constant pressure perfusion lasting 60 minutes in one randomly chosen eye of each animal. Mean outflow facility was 0.26 +/- 0.07 microliter/(min) (mmHg) using tonography and 0.26 +/- 0.6 microliter/(min) (mmHg) using constant pressure perfusion. These values are similar (p greater than 0.6) and show significant correlation (r = 0.914, p less than 0.001). Constant pressure perfusion was associated with a time-dependent facility increase, and with increased flow and stable resistance at higher infusion pressures. These results suggest that tonography may represent a repeatable, reproducible, and valid noninvasive technique to monitor outflow facility in this animal. This may be important in the evaluation of medications which alter wound healing after glaucoma filter surgery.

Animals↗

PubMed1987

The rabbit ear pedicle flap. A new model for evaluating factors affecting the circulation in flaps.

Laser Doppler flowmetry and transcutaneous oximetry were compared regarding their speed and accuracy in detecting occlusion of the artery of an experimental rabbit ear pedicle flap. The laser Doppler flowmeter showed a significant decrease in flow and the transcutaneous oximeter showed a significant decrease in oxygen tension within one minute after occlusion of the artery. A significant increase in flow was observed within one minute, and a significant increase in oxygen tension readings was observed one minute after the artery was opened. A steady state after opening the artery was reached sooner for the laser Doppler flowmeter readings. This study suggests that laser Doppler flowmetry and transcutaneous oximetry are equally fast and accurate in detecting changes in blood flow to a pedicle graft. These methods also have equally good reproducibility. Repeated clampings within a 30 min period did not affect the measured parameters.

Animals↗

PubMedDate not supplied

[Ratio of r- and K-forms of selection in life cycles of trematodes (Plathelminthes, Trematoda).

The situation is considered in a continuum of r-K-selection of hermaphroditic and parthenogenetic populations of trematodes (fish parasites) of three species: Bunodera luciopercae, Sphaerostomum bramae, and Phyllodistomum elongatum. Maritae of B. luciopercae and S. bramae are characterized by a low fertility, single-type reproduction, and long prereproductive period, and are involved in interspecific competition. On the contrary, maritae of Ph. elongatum rapidly mature, are highly fertile, repeatedly reproduce, and occur in a "competitive vacuum". Pathenitae of these trematodes combine the features of both forms of selection, which is accounted for by adaptations to the parasitic mode of life. A reproductive tactic of parthenitae has been proposed, based on the redioid or sporocystoid types. According to the community of features, B luciopercae as a species is a "K-strategiest", S. bramae equally combines the features of both forms of selection, and Ph. elongatum is an "r-strategist".

Animals↗

PubMed1976

[Effect of synovial fluid from rheumatoid arthritis patients on leukocyte migration].

By means of the migration inhibition test, the influence of the synovial fluid of rheumatoid arthritis patients on normal blood lymphocytes was investigated. There was the hypothesis that the migration inhibitory factor is already formed in the synovial membrane of rheumatoid arthritis patients. In 35 cases a migration inhibition could be demonstrated, in 3 cases the migration of normal lymphocytes remained uninfluenced, in 6 cases a migration enhancement occurred. The demonstration of the rheumatic factor in the synovial fluids used was partly positive, partly negative. Especially the demonstration of a migration enhancement--this phenomenon could be reproduced repeatedly--cannot yet be interpreted unequivocally and requires further investigations.

Arthritis, Rheumatoid↗

PubMed1986

Automated kinetic assay of angiotensin-converting enzyme in serum.

We have developed and validated an automated kinetic method for angiotensin-converting enzyme (EC 3.4.15.1) on the Olli C + D analyzer, modified from that of Ronca-Testoni (Clin Chem 1983;29:1093-6) with N-[3-(2-furyl)-acryloyl]-L-phenylalanylglycylglycine used as substrate. We have determined appropriate reaction conditions for the assay, verified the principal analytical reliability criteria (repeatability, reproducibility, sensitivity), and established normal reference intervals (mean +/- SD) for the enzyme's activity, using serum of normal adults (100 +/- 35 U/L, n = 150), newborns (130 +/- 27 U/L, n = 10), women taking oral contraceptives (103 +/- 30 U/L, n = 10), smokers (109 +/- 38 U/L, n = 27), and patients with sarcoidosis (220 +/- 48 U/L, n = 15).

Adult↗

PubMed1988

[Activated thromboplastin time, plasma heparin and plasma fibrinogen using the Fibrintimer 10].

After a thorough study, and having chosen the machine that is to equip an average sized haemostasis laboratory, the installation then requires certain steps (the reorganisation of work, better adapted reagents, a change of normality, a fine tuning of the technics, the time to get used to the machine). In this perspective, this work describes the regulation of the technic to determine the heparin activity on the Fibrintimer 10 (F 10) by chronometry (thrombin clotting time with variable concentration), a study of the repeatability and reproducibility of activated partial thromboplastin time (APTT), plasma heparin (HEP) and fibrinogen on the Fibrintimer 10, a study of the correlation between the results we got with the F 10 and the thermostat water-bath for the APTT and the HEP and between those we got on the F 10 and the fibrometer for the fibrinogen. The F 10 has allowed us to save more time whilst keeping the same technics and reagents. The determination of the heparin activity, by thrombin clotting time with variable concentration, gives us a method which is quick, cheap and useful for the following-up of the patients undergoing a treatment with standard heparin. The reproducibility and repeatability prove to be good for the 3 tests in our operatory conditions as well as the correlations between the results we get with both methods.

Adult↗

PubMed1985

[Relaxation and filling of the left ventricle measured by computer analysis of the unidimensional (M-type) echocardiogram in healthy subjects and patients with hypertrophic cardiomyopathy].

The indices of systolic and earli diastolic function (relaxation and rapid filling) were established in 16 healthy subjects and 35 patients with idiopathic hypertrophic cardiomyopathy by computer analysis ("Echocomputer" RIEMT--MA, Sofia) and left ventricular and mitral valve M-type echocardiogram. In a considerable part of the partients with hypertrophic cardiomyopathy, pathological changes were established in the diastolic function of left ventricle--lengthening of iso-voluminal relaxition, reduction of velocity and increase of the dimension of left ventricular cavity, reduction of velocity and fraction of blood flow in the phase of rapid filling of left ventricle. Those changes of diastolic function are a manifestation of increased resistance, restriction of left ventricular filling that could partially explain the tendency to reduction of stroke and minute volume in some patients with hypertrophic cardiomyopathy with normal and increased indices of systolic function of left ventricle (fraction of shortening, ejection fraction, veloycity of reduction of dimension of left ventricle in the phase of ejection)? There is considerable correlation between the changes of diastolic function and those of the hypetrophic process and reduction of left ventricular cavity. The computer analysis of the echogram, enables the more detailed, fast and accurate determination of important indices of diastolic and systolic function of left ventricle, with a good repeated reproducibility.

Adult↗

PubMed1979

The suicide technique in vitro for granulocytic progenitor cells (CFC) by application of hydroxyurea (HU) to low concentrations of human bone marrow cells.

A suicide technique applicable to human bone marrow granulocytic progenitor cells has been previously described (3). This study discusses the conditions for its use on bone marrow aspirates poor in cells. When the number of cells exposed to hydroxyurea (HU) is proportional to the quantity of HU it is possible to avoid artifacts due to HU toxicity. This technique can repeatedly reproduce a 40--50% suicide. To obtain this result we suggest using a 6.10(-6) mM/ml/cell HU concentration.

Bone Marrow↗

PubMed1971

Serum digoxin by radioimmunoassay.

Using the radioimmunoassay technique for measuring serum digoxin, it was found that patients who were given 0.25 mg. digoxin orally per day had a mean serum level of 0.83 +/- 0.06 ng. per ml. In patients given 0.5 mg. daily the mean level was 1.30 +/- 0.14 ng. A higher 24-hour urinary excretion of digoxin was associated with the higher serum levels in the latter group. Individuals who exhibited electrocardiographic evidence of digoxin toxicity had a mean serum level of 2.81 +/- 0.21 ng. The majority of patients with high serum levels had evidence of impaired renal function, and it is in this clinical situation that knowledge of serum digoxin levels is likely to be most helpful in determining dose schedules.The method is specific, sensitive and reproducible. Repeated measurements on the same patient on maintenance therapy showed little variation. To obtain dependable serum levels blood should be drawn at least five hours after oral, and three hours after intravenous administration.

Administration, Oral↗

PubMed1979

[Comparative study of digoxin determination by E.L.I.S.A. and radioimmunoassay techniques (author's transl)].

This study is based on a double blind interlaboratory comparison between radioimmunoassay and E.L.I.S.A. digoxin determination. The correlation between digoxin values found with these two methods is good (r = 0.96 for therapeutic and toxic ranges 1,0 ng/ml - 5,5 ng/ml). The results indicate good repeatability, reproducibility and precision. The determination by E.L.I.S.A. can be performed with sera or plasma. The presence of haemolysis makes no appreciable difference in results. No variation is observed when different kits are used from an identical lot. However digoxin gives an important cross reactivity with digitoxin in Enzymeimmunoassay. Therefore it is necessary to know exactly the digitalis glycoside before the determination in order to avoid significant error.

Digoxin↗

PubMed1982

[Serum amylase determination : automated continuous flow method (author's transl)].

A simple automated assay was described for the determination of serum amylase using a chromogenic substrate. The reaction was stopped by filtration across a cellulose nitrate membrane. The analytic parameters of this method were studied. Repeatability, reproducibility and precision were convenient. The calibration curve was linear up to 850 U/I. An excellent correlation was obtained after comparison with the manual method (Phadebas amylase test). The effects of haemolysis and very high ascorbic concentrations of bilirubin, glucose, uric acid and ascorbic acid were negligible on the value measured. The serum turbidity was alone to induce a variation by excess.

Amylases↗

PubMedDate not supplied

[Susceptibility of Ornithodoros papillipes (Argasidae) ticks to the rickettsia Coxiella burnetii].

A definition of susceptibility of an arthropod to an infectious or invasional agent is given. The susceptibility means a capacity of the arthropod for infection in a result of which the agent either completes a part of its life cycle in the organism of its invertebrate host or reproduces repeatedly in the organs and tissues of its internal medium causing or not causing a noticeable damage. On the model of the tick O. papillipes and Q. fever agent there were shown differences in the resistance of arthropods to Rickettsiae depending on the developmental phase of the invertebrate host. Under otherwise equal conditions the susceptibility of nymphs of O. papillipes to C. burnetii was in nymph II 146 times, in nymph I 280 times and in larvae 50 000 times less than in nymph IV. It has been established that nymphs I, II, and IV engorge blood only 2.5, 14 and 50 times more respectively than larvae. It shows that the success of infection depends to a larger extent on the degree of susceptibility of an arthropod to a corresponding agent than on the quantity of engorged infected blood. The formula of estimation of agent concentration necessary for successful infection of 50 per cent of ticks is given.

Animals↗

PubMed1981

[A rapid technique for extraction of urinary 17-kéto and 17-hydroxy-corticosteroids by chromatography (author's transl)].

The extraction ot total urinary 17-keto and 17-hydroxy steroids has been effected by a rapid procedure involving pre-packed kieselguhr column chromatography. This work successively studies the correlation of this technique with the classical extraction by mechanical agitation (42 and 61 subjects), its reproducibility, repeatability and recovery of added internal standards. The proposed method seems convenient for routine clinical analysis.

17-Hydroxycorticosteroids↗

PubMed1982

Phleborheography--results of a ten-year experience.

Phleborheography (PRG) is a physiologic volumetric plethysmographic technique that was developed for the diagnosis of lower extremity deep venous thrombosis. During the past 10 years, 21, 626 extremities have been studied with 709 corresponding venograms. Overall data reveal a sensitivity of 92% (247/268) and specificity of 95% (418/441). There were 21 false negative PRG results, and 12 of these were due to isolated calf vein thrombosis. There were 23 false positive results, and 11 of these were considered true errors of the technique. When isolated calf vein thrombosis was disregarded, the sensitivity increased to 95%. PRG detected 45 of 57 (79%) isolated calf vein thrombi. The modified criteria for interpretation included respiratory waves and baseline elevation as the major criteria and prominent arterial pulsation and foot emptying as the minor criteria. PRG has recently been used to monitor the duration of thrombolytic therapy. While data are limited, this appears to be a promising contribution to the quantification of individual response to lytic therapy and may indicate an objective end point for treatment. PRG is a sensitive and specific method of detecting deep vein obstruction. It is a painless, reproducible, repeatable technique that requires minimal patient cooperation. PRG is a versatile laboratory technique that can be used for a variety of applications in addition to the diagnosis of deep vein thrombosis.

False Negative Reactions↗

PubMed1980

[Assay of 3-methoxy 4-hydroxyphenyl ethylene glycol (MHPG) and its conjugates in the urine (author's transl)].

Urinary MHPG was assayed by gas chromatography using a flame ionisation detector. The technic proposed was reproducible, repeatable and linear. The frequent values determined in adult subjects of both sexes were 8.64 1.34 mumol/24 h without any difference between the sexes. On the other hand, urinary excretion of total MHPG showed a positive correlation with age. It was excreted in the conjugated form, of which 50 p. cent was sulphoconjugated, 41 p. cent glucuroconjugated, and 9 p. cent free. Owing to its simplicity, this method may be applied to the study of mood disorders.

Adult↗

PubMed1995

[Methods for determining lead and cadmium in blood; cadmium, copper, nickel and chromium in urine using flameless atomic absorption spectrometry].

The estimation of environmental and occupational exposure to metals is based on the determination of metal concentrations in biological material. This paper describes methods for determining lead and cadmium in blood, and cadmium, copper, nickel and chromium in urine. The methods are evaluated in view of their linearity, precision, repeatability, reproducibility and detectability. The reliability of the methods was verified by determining lyphilized standards of known metal concentrations (Behring). The reproducibility expressed by the value of relative standard deviation ranged from 1.2% to 7.8%. In the case of lead and cadmium determinations, the reliability of results was confirmed due to the participation of our laboratory in the UK NEQAS external control project, the Queen Elizabeth Hospital, Birmingham. The results of external quality control (MR VIS = 19 for lead, as compared with the mean = 41 for all the project participants and MR VIS = 29 for cadmium, mean = 62) prove undoubtedly correctness of the methods applied. A small volume of sample to be analyzed is their major advantage, and due to adopted analytical parameters the methods can be used to determine metals in biological material in order to assess occupational or environmental exposure.

Cadmium↗