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Results for “Repeatability and Reproducibility”

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PubMed2006

European multicenter evaluation of high-density DNA probe arrays for detection of hepatitis B virus resistance mutations and identification of genotypes.

Polymorphisms along the hepatitis B virus (HBV) genome have an impact on disease outcome, sensitivity to antiviral treatment, escape from vaccination, and laboratory diagnosis. We have designed a diagnostic tool based on duplex amplification of the whole HBV genome and a high-density DNA chip designed to detect 245 mutations, 20 deletions, and 2 insertions at 151 positions and to determine the genotype of the virus in serum. Assay performances were evaluated with 170 samples, characterized by determination of viral load and sequencing of the Pol, S, and precore genes and the basal core promoter. One hundred fifty-three samples (90%) could be amplified and analyzed by the chip. Only two samples with more than 10(3) genome copies/ml could not be analyzed. Genotype had no impact on analytical sensitivity. Reproducibility studies showed no difference between repeats for codon and genotype determination. Genotype determination by sequencing and the chip were concordant in 148 of 151 samples. Twelve thousand one hundred sixty-one codons were analyzed by both techniques. Only 89.4% could be determined by sequencing, and among the remaining 11,335 codons, 92.8% were identical by sequencing and the chip. Failures to identify an amino acid by the chip were mainly due to reduced hybridization efficiency attributed to unexpected polymorphisms. Optimization of the chip-based reagent for the analysis of the HBV genome is ongoing. This first evaluation showed that DNA chip technology can provide important information in relation to the clinical management of chronic hepatitis B.

DNA, Viral↗
PubMed1990

[Evaluation of exercise test reproducibility in patients with ischemic cardiopathy].

We evaluated the repeatability of some measurements taken during the bicycle ergometer exercise test (exercise duration, heart rate and pressure rate product at angina and ST segment depression times) in 166 consecutive non-selected ambulatory patients with proven ischemic heart disease. One hundred and sixty-six patients with history of angina and/or myocardial infarction performed three exercise tests within seven days of wash-out. Eighty-six (58.1%) of these experienced angina and ischemic ST segment depression during all three tests (group 1), and 80 (48.2%) finished at least one test without angina or ST segment depression (group 2). The degree of angina (according to Canadian Cardiovascular Society classification) was higher in the first group than in the second one; on the contrary, exercise duration as well as pressure rate product at ischemic threshold, heart rate and pressure rate product at the onset of angina were significantly lower (0.001 less than p less than 0.05) in the former group. In group 1, we analyzed ergometric parameter measurement "repeatability" during the three consecutive exercise tests. The analysis of variance for repeated measurements showed that exercise duration and pressure rate product values at ischemic threshold did not vary significantly in the three tests, while other ergometric parameters showed a greater variability (0.001 less than p less than 0.05). Age, previous myocardial infarction or rest angina, the number of critically stenotic coronary vessels and the ejection fraction did not condition the repeatability of the test. In conclusion, in our population of non-selected ischemic patients only 52% developed angina and ischemic ST segment depression during all three exercise tests performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2001

Evaluation of BACTEC Mycobacteria Growth Indicator Tube (MGIT 960) automated system for drug susceptibility testing of Mycobacterium tuberculosis.

The reliability of the BACTEC MGIT 960 system, an automated version of the Mycobacteria Growth Indicator Tube (MGIT), for antimicrobial susceptibility testing of Mycobacterium tuberculosis was evaluated on 78 clinical isolates. Rifampin (RMP), isoniazid (INH), streptomycin (SM), and ethambutol (EMB) were tested at the following concentrations: 1.0 microg/ml for RMP, 0.1 and 0.4 microg/ml for INH, 1.0 and 4.0 microg/ml for SM, and 5.0 and 7.5 microg/ml for EMB. Results were compared with those obtained by the BACTEC 460 TB radiometric system. Initially the reproducibility study showed 99.5% agreement on repeat testing with all the four drugs. With susceptibility testing of clinical isolates, excellent agreement between the two systems was found for all the drugs. A total of nine major errors were observed for only three isolates, resistant according to BACTEC MGIT 960 and susceptible according to BACTEC 460 TB, to SM (4.0 microg/ml), INH (0.1 microg/ml), and EMB (5.0 microg/ml) (one isolate) and to SM (1.0 microg/ml), INH (0.4 microg/ml), and EMB (5.0 microg/ml) (two isolates). When these isolates were tested by using the conventional proportion method on Löwenstein-Jensen medium, agreement with BACTEC MGIT 960 was found for five results and with BACTEC 460 TB for the remainder. The time to report results was 7.9 days by MGIT 960 and 7.3 days by BACTEC 460 TB, which was not found statistically significant (P > 0.05). In conclusion, the performance of BACTEC MGIT 960 was found similar to that of BACTEC 460 TB and this new system can be considered a good alternative to the radiometric method for routine susceptibility testing of M. tuberculosis.

Antitubercular Agents↗
PubMed2002

Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.

The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.

Amino Acid Sequence↗
PubMed2006

Energy demands of walking in persons with postpoliomyelitis syndrome: relationship with muscle strength and reproducibility.

OBJECTIVES: To describe the energy demands of walking in subjects with postpoliomyelitis syndrome (PPS) in comparison with the demands in healthy subjects, and to assess the reproducibility of walking energy measurements. DESIGN: Four repeated measurements with a 1-week interval between each measurement. SETTING: Outpatient clinic of a university hospital. PARTICIPANTS: Fourteen subjects with PPS and 14 age- and sex-matched healthy subjects. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Walking speed and energy cost of walking. The correlation parameter was lower-extremity muscle strength sum (MSS). The reproducibility parameters were standard error (SE) of measurement and smallest detectable difference (SDD). RESULTS: Walking speed in subjects with PPS (61.8 m/min) was significantly lower (-28%) and energy cost (4.8 J.kg(-1).m(-1)) was significantly higher (40%) than in healthy subjects. MSS correlated strongly with energy cost (r=-.84, P=.000), explaining 71% of the variance. The SE of measurement of energy cost measurements ranged between 1.7% and 3.4% for PPS subjects and between 1.2% and 2.4% for healthy subjects. The SDD ranged between 4.6% and 9.4% for PPS subjects and between 3.3% and 6.6% for healthy subjects, depending on the number of repeated measurements that were considered. CONCLUSIONS: Energy cost of walking in subjects with PPS is strongly related to the extent of muscle weakness in the lower extremities. Although variability was greater for PPS subjects than for healthy subjects, reproducibility of energy cost measurements was high. Therefore, metabolic assessment of energy cost of walking is a sensitive tool that can reveal clinically relevant changes even in the condition of a person with PPS.

Adult↗
PubMed1999

[Reproducibility of the walking test in patients with cystic fibrosis].

OBJECTIVE: The walking test is a useful and objective method for evaluating the tolerance for exercise in patients with chronic bronchopulmonary diseases. Our objective was to check the reproducibility of this test and evaluate whether there are differences between tests of varying duration (2 and 6 minutes) in a group of patients with cystic fibrosis. PATIENTS AND METHODS: We utilized the walking test on 29 patients who were in a stable phase and under care in the Cystic Fibrosis Unit of our hospital. Two tests were carried out, one of 2 minutes and the other of 6 minutes duration, both of which were repeated after a 15-minute interval. RESULTS: The reproducibility of the walking test in this type of patient was very good and we found an excellent correlation between the two-minute test and the six-minute test. We did not observe a training effect when the test was repeated. CONCLUSIONS: The two minute walking test has a high reproducibility and we propose this test, because it is shorter and more comfortable for pediatric patients with cystic fibrosis, in order to evaluate the evolution, progressive deterioration of the of the patient and the response to different types of treatments.

Adolescent↗
PubMedDate not supplied

The effects of high-dose ivermectin regimens on Onchocerca volvulus in onchocerciasis patients.

Ivermectin, at the standard dose of 150 micrograms/kg bodyweight, does not kill the adult worms of Onchocerca volvulus and does not disrupt embryogenesis or spermatogenesis. Repeated standard doses, if maintained, arrest microfilarial production but result in only a mild-to-modest macrofilaricidal effect. We investigated whether high doses would effectively kill the adult worms, and whether cessation of microfilarial production could be reproduced by an equivalent, single, high dose. One hundred men participated in a double-blind placebo-controlled trial and received increasing doses of ivermectin from 150 micrograms/kg to 1600 micrograms/kg bodyweight. Nodules were excised at day 180 and examined by histopathology. Total doses of ivermectin up to 1600 micrograms/kg were not significantly more effective than 150 micrograms/kg. Moreover, they did not reproduce the marked inhibitory effects of the repeat standard-dose regimens on embryogenesis, nor the modest effect on adult worm viability, at comparable total doses. These effects may be functions of multiplicities of dosages rather than of the total dose. Our findings also suggest that repeated high-dose regimens are unlikely to be more effective than a similar number of 150 micrograms/kg doses. This deficiency of ivermectin requires that the search for macrofilaricides remains a top priority.

Animals↗
PubMed1995

DNA fingerprinting and forensic medicine.

In forensic medicine, DNA fingerprinting for identification is becoming a necessary procedure. A method to radiolabel M13 DNA probe by primer extension using a specific oligonucleotide primer was developed. The method specifically labeled the two 15 bp repeats in M13 DNA which hybridize to target DNA giving rise to DNA fingerprinting patterns. The M13 probe labeled by this method has proven useful for individual identification, paternity testing and monitoring reconstitution in bone marrow transplantation. The genetic locus D1S80 and D17S30 containing a variable number of tandem repeats (VNTR) have also been successfully amplified from human genomic DNA isolated from blood (50 ng from each sample) by the polymerase chain reaction (PCR) using oligonucleotide primers complementary to the flanking sequences as primers for amplification. DNA bands were detected by ethidium bromide staining after electrophoresis on agarose gels. Analysis of this VNTR locus was thus achieved without the need for Southern blot or radioactive material. The small size of the DNA fragments produced in the PCR amplification permited good resolution of individual alleles. The precise specification of the number of tandem repeats present in each allelic fragment was reproducible from one analysis to another.

Base Sequence↗
PubMed1999

Recording the photopic electroretinogram from conscious adult Yucatan micropigs.

The micropig is viewed by many as one of the best animal models of human system physiology. The purpose of this study was to develop a simple, rapid and reliable method to record clinical electroretinograms from conscious adult Yucatan micropigs. Photopic ERGs were recorded from 18 conscious animals following a 3-h period of preadaptation to a moderate photopic environment. Rectal temperature and blood pressure were monitored throughout the experiment. In order to test the reproducibility of our procedure, the same protocol was repeated (n=6 micropigs) on three different recording sessions each separated by a 48-h period. Our results indicate that the recording of reproducible ERGs, in the conscious Yucatan micropig, is feasible provided that an adequate experimental approach is used. We believe that our method will enable investigators to perform retinal physiology experiments using an approach which is compatible with that used in a human clinical setup thus facilitating the transposition of experimental data from animal to human.

Adaptation, Ocular↗
PubMed1995

Highly discriminating heptaplex short tandem repeat PCR system for forensic identification.

We describe a highly discriminating multiplex short tandem repeat PCR human identification system that gives a matching probability for Caucasians of European ancestry of 2.94 x 10(-8) or 5.66 x 10(-10) when used in combination with a previously described system. The system produces discrimination equal to or greater than four single locus probes (restriction fragment length polymorphism [RFLP] typing of variable nucleotide tandem repeat [VNTR] loci). The test is robust and reproducible and works with 1-10 ng of template DNA, using fluorescent detection of PCR products from either 4 or 6 short tandem repeat loci and the X-Y homologous gene amelogenin, giving simultaneous sex diagnosis.

Alleles↗
PubMed1985

[Evaluation of intermittent claudication using a treadmill with measurement of systolic pressure at the ankle following exercise].

Intermittent claudication (IC) and maximum walking distance (MWD) were studied in 173 patients and compared to post-stress Doppler claudicant ankle pressure (PSCAP) and to ankle index (PSCAI) recorded 2 minutes after exercise. Self-evaluation of MWD by the patient was inaccurate in 60% of cases. The treadmill testing (at 12% of rate and 2 miles/hour) exhibited a clinically overt IC in 93 cases with MWD of 166 m +/- 76, a PSCAP of 24 mm Hg +/- 24 and a PSCAI of 0.17 +/- 0.17. A clinically questionable IC occurred in 50 cases with significantly higher values (p less than 0.001) for MWD (278 m +/- 75) PSCAP (52 mm Hg +/- 24) and PSCAI (0.34 +/- 0.16). In 30 cases without IC after 400 m on treadmill, the PSCAP (81 mm HG +/- 26) and the PSCAI (0.57 +/- 0.18) were significantly (p less than 0.001) higher than in IC groups and related to milder iliofemoral stenosis. Overall reproducibility of MWD (mean = 190 m +/- 90) with 2 or 3 repeated measures in 75 cases, was 10.8% +/- 8.6 with large individual variations. Overall reproducibility of PSCAP after standardized treadmill testing in 42 cases was 6.5 +/- 5.3 (range of CV = 0 to 16%). A variation of PSCAP of more than 15 mm Hg is considered significant at level 0.01. It is concluded that overt IC with foot pallor and PSACP at 40 mm Hg or less reflects actual and reproducible MWD (especially below 300 m).(ABSTRACT TRUNCATED AT 250 WORDS)

Ankle↗
PubMedDate not supplied

Evidence for neuromuscular fatigue during high-intensity cycling in warm, humid conditions.

The purpose of this study was to examine and describe the neuromuscular changes associated with fatigue using a self-paced cycling protocol of 60-min duration, under warm, humid conditions. Eleven subjects [mean (SE) age 21.8 (0.8) years; height 174.9 (3.0) cm; body mass 74.8 (2.7) kg; maximum oxygen consumption 50.3 (1.8) ml.kg.min-1] performed one 60-min self-paced cycling time trial punctuated with six 1-min "all out" sprints at 10-min intervals, while 4 subjects repeated the trial for the purpose of determining reproducibility. Power output, integrated electromyographic signal (IEMG), and mean percentile frequency shifts (MPFS) were recorded at the mid-point of each sprint. There were no differences between trials for EMG variables, distance cycled, mean heart rate, and subjective rating of perceived exertion for the subjects who repeated the trial (n = 4). The results from the repeated trials suggest that neuromuscular responses to self-paced cycling are reproducible between trials. The mean heart rate for the 11 subjects was 163.6 (0.71) beats.min-1. Values for power output and IEMG expressed as a percentage of that recorded for the initial sprint decreased during sprints 2-5, with normalised values being 94%, 91%, 87% and 87%, respectively, and 71%, 71%, 73%, and 77%, respectively. However, during the final sprint normalised power output and IEMG increased to 94% and 90% of initial values, respectively. MPFS displayed an increase with time; however, this was not significant (P = 0.06). The main finding of this investigation is the ability of subjects to return power output to near initial values during the final of six maximal effort sprints that were included as part of a self-paced cycling protocol. This appears to be due to a combination of changes in neuromuscular recruitment, central or peripheral control systems, or the EMG signal itself. Further investigations in which changes in multiple physiological systems are assessed systematically are required so that the underlying mechanisms related to the development of fatigue during normal dynamic movements such as cycling can be more clearly delineated.

Adolescent↗
PubMed1991

The reproducibility and heritability of individual differences in osmoregulatory function in normal human subjects.

The rise in plasma vasopressin produced by infusion of hypertonic saline varies widely among healthy adults. To determine if these interindividual differences are reproducible, we used linear regression to analyze the relationship of plasma vasopressin to plasma osmolality during repeat hypertonic saline infusion in seven normal subjects. The results confirmed that the slope or sensitivity of the relationship differed widely between subjects (0.12 to 1.66 pg/ml/mOsm/kg) and revealed that these differences were highly reproducible. (r = 0.94 on repeat testing). The individual values for osmotic threshold were less variable (280 to 288 mOsm/kg) as well as less clearly reproducible (r = 0.61). To determine whether these differences are genetically influenced, we compared the vasopressin osmolality relationships within seven monozygotic and six dizygotic twin pairs. We found that the threshold and sensitivity values correlated significantly within monozygotes (r = 0.95 and 0.95) but not within dizygotes (r = 0.34 and 0.21). When the osmoregulation of thirst was similarly evaluated, the individual relationships were as variable as for plasma vasopressin, but only the threshold values in monozygotes correlated significantly (r = 0.92). In 80 healthy adults, the frequency distributions of the osmotic threshold and sensitivity of the vasopressin responses were essentially normal. We conclude that the sensitivity for vasopressin secretion as well as the osmotic thresholds for thirst and vasopressin demonstrate significant polygenetic variance among healthy adults.

Adult↗
PubMed1999

p205 is a major target of autoreactive T cells in rheumatoid arthritis.

OBJECTIVE: The p205 autoantigen and interleukin-2 (IL-2) function synergistically to stimulate T lymphocytes from patients with rheumatoid arthritis (RA), and a p205-derived amino acid sequence is identical to an immunoglobulin sequence located within a domain that is reactive with rheumatoid factors (RF). This study was conducted to analyze in detail the T cell immune response against p205 and to investigate whether immunity to p205 may play a role in T cell-mediated immunopathology in active RA. METHODS: Cibachron blue, protein A-Sepharose, and gel filtration on Sephacryl were used successively to enrich p205 from synovial fluid (SF). T lymphocytes from RA patients were isolated from the peripheral blood (PB), lymph nodes, and SF, and p205 and peptides derived from known sequences were assessed by T cell proliferation assays in the presence of IL-2. RESULTS: P205-specific proliferation of T cells was observed in PB as well as in SF. When p205 was isolated from RA SF, proliferation of RA T cells peaked on day 3. With p205 purified from SF from trauma patients, there was a significant shift of the maximum T cell proliferation to day 8. T cells were of CD4 or CD8 phenotype, and B cells did not proliferate to a significant degree. The T cell response to p205 was always higher for SF mononuclear cells (SFMC) compared with PBMC (P < 0.001). In 1 RA patient who underwent repeated leukapheresis, this led to a reproducible decline in p205-specific T cell proliferation to control levels. PB T cells specifically proliferating in response to p205 were detected in 20 of 32 RA patients (63%). Of 26 patients with other inflammatory rheumatic diseases, only 1 showed a minor response to p205, while normal donors did not demonstrate a significant T cell proliferation. A synthetic p205-derived peptide, with an amino acid sequence identical to an immunoglobulin sequence located in the area where RF binds, was reactive with T cells from RA patients. CONCLUSION: P205 appears to be a major target of autoreactive T cells in RA. P205-specific T cells are primed and more abundant at the site of inflammation. As a T cell target in RA, p205 may well be an antigen involved in the initiation of RF production.

Adult↗
PubMed1993

Investigation of retroviral involvement in chronic fatigue syndrome.

Within the last few years significant efforts have been made to identify objective reliable diagnostic markers from individuals with chronic fatigue syndrome (CFS). We report the absence of a previously described retroviral marker (HTLV-II gag) in a blinded study of CFS cases. Even with excellent reproducible sensitivities, this marker failed in repeated attempts to distinguish cases from controls. In addition, four other retroviruses (simian T cell leukaemia virus, human spumavirus, bovine leukaemia virus and simian retrovirus) were examined for their presence in these CFS cases and found to be absent. Our findings suggest that these agents, at least as markers, are non-distinguishing for CFS and that other factors may be confounding the resolution of an aetiology to this syndrome.

Biomarkers↗
PubMed1991

Study of belching ability in antireflux surgery patients and normal volunteers.

The ability to belch was evaluated by a novel test, after gaseous stomach distension to standard volume, in 16 patients after antireflux surgery and nine healthy volunteers. A structured assessment of dyspeptic symptoms was also carried out in both groups. Repeat studies in volunteers showed acceptable reproducibility for the new test of belching capacity (within-subject coefficient of variance 4.5 per cent). After antireflux surgery, patients had lower volume individual belches (median(range) 27.5(0-104) ml in patients versus 76(15-165) ml in volunteers; P less than 0.02) and belched less gas within 1 h of the stimulus than volunteers (median(range) 205(0-1363) ml in patients versus 456(45-818) ml in volunteers; P less than 0.05). Belching frequency was similar in both groups. The incidence and severity of symptoms were unrelated to belched gas volumes.

Adult↗
PubMed2003

Capillary electrophoresis coupled to time of flight-mass spectrometry of therapeutic peptide hormones.

We have established a method for separation and characterization of a series of peptide hormones of pharmaceutical interest and wide therapeutical use by capillary electrophoresis-electrospray-mass spectrometry (CE-ES-MS) using a sheath flow interface. Several parameters were systematically investigated, such as concentration of the electrolyte, organic solvent and sheath liquid composition, gas flow rates and capillary position. Moreover, limits of detection, linearity, repeatability and day-to-day reproducibility of the proposed method were studied in order to obtain the main quality parameters.

Electrolytes↗