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At least 1,657 records · Page 92Linked to original sources
PubMed1994

Improvement of hepatitis C virus RNA polymerase chain reaction through a multicentre quality control study. French Study Group for the Standardization of Hepatitis C Virus PCR.

Nine French laboratories, using the polymerase chain reaction (PCR) for detection of hepatitis C virus (HCV) RNA, initiated a quality control study to assess and to improve the specificity and sensitivity of their procedures. The study was carried out in three rounds, based on coded panels consisting of anti-HCV positive and anti-HCV negative samples. For the first panel, each laboratory followed its own protocol: 100% sensitivity was observed in two laboratories, 100% specificity in seven. For the second panel, all laboratories were required to use both their own procedure and a consensus procedure established from those laboratories which provided the best results on the first panel. With their own procedure, 100% sensitivity was observed in five laboratories and 100% specificity in all. With the common procedure, 100% sensitivity was observed in all but one, and 100% specificity in all. The third panel included three positive samples with four successive dilutions. For two samples, 8/8 laboratories had positive signals until the 1/100 dilution and discrepant results beyond this dilution; for the third sample, the signals were more discrepant. These results indicate that optimization and standardization of PCR may help laboratories to improve their procedure.

Base Sequence↗
PubMed2006

Three-color cDNA microarrays with prehybridization quality control yield gene expression data comparable to that of commercial platforms.

Despite their lower cost and high content flexibility, a limitation of in-house-prepared arrays has been their susceptibility to quality control (QC) issues and lack of QC standards across laboratories. Therefore, we developed a novel three-color array system that allows prehybridization QC as well as the Matarray software to facilitate acquisition of accurate gene expression data. In this study, we compared performance of our rat cDNA array to the Affymetrix RG-U34A and Agilent G4130A arrays using 2,824 UniGenes represented on all three arrays. Before data filtering, poor interplatform agreement was observed; however, after data filtering, differentially expressed UniGenes exhibited correlation coefficients of 0.91, 0.88, and 0.92 between the Affymetrix vs. Agilent, Affymetrix vs. cDNA, and Agilent vs. cDNA arrays, respectively. The Affymetrix, Agilent, and cDNA arrays agreed well with quantitative RT-PCR conducted on 42 UniGenes, yielding correlation coefficients of 0.90, 0.90, and 0.96, respectively. Each platform underestimated ratios relative to quantitative RT-PCR, possessing respective slopes of 0.86 (R2 = 0.81), 0.65 (R2 = 0.81), and 0.70 (R2 = 0.92). Overall, these data show that the combination of our novel technical and analytic approaches yield an accurate platform for functional genomics that is concordant with commercial discovery arrays in terms of identifying regulated genes and pathways.

Analysis of Variance↗
PubMedDate not supplied

Biological and chemical quality control of spermicidal raw material nonoxynol-9 and nonoxynol-9 containing vaginal contraceptive (ABF contraceptive film): determination of spermicidal activity and assay of nonoxynol-9.

The paper presents a routine biological and chemical quality control of nonoxynol-9 raw material and pharmaceutical formulation containing nonoxynol-9 (ABF contraceptive film). The biological control performed based on the determination and comparison of the spermicidal activities different dilutions of the standard raw materials solution and assay raw material or nonoxynol-9 pharmaceutical formulation solution on the human or breeding bull sperm using a modified Sander-Cramer method. The test preparations of the nonoxynol-9 raw materials or pharmaceutical formulation should show equal or higher spermicidal activity than the standard. The spermicidal activity should not be lower than dilution 1:90. The chemical control is performed based on the determination and comparison of nonoxynol-9 content in the standard raw material solution and assay raw material or nonoxynol-9 pharmaceutical formulation solution using UV-spectrophotometric method determining and comparing the absorbances at the maximum absorbance wavelength (275 nm). The content of nonoxynol-9 in the raw material assay solution or pharmaceutical formulation (ABF contraceptive film) should be within 90-110% of the declared value.

Animals↗
PubMed1995

Molecular characterization and multilaboratory evaluation of Enterococcus faecalis ATCC 51299 for quality control of screening tests for vancomycin and high-level aminoglycoside resistance in enterococci.

Studies were conducted to validate the use of Enterococcus faecalis ATCC 51299 (which is vancomycin resistant and resistant to high levels of gentamicin and streptomycin) and E. faecalis ATCC 29212 (which is susceptible to vancomycin and against which gentamicin or streptomycin and cell wall-active agents have synergistic kill activity) as controls in an agar screening test for vancomycin resistance and high-level streptomycin and gentamicin resistance and a broth microdilution screening test for high-level streptomycin and gentamicin resistance. Both organisms performed as expected in these tests and will serve as appropriate controls. However, E. faecalis ATCC 29212 was occasionally noted to produce light growth on the vancomycin screening plate with certain lots of agar. Quality control ranges for disk diffusion tests with disks with large amounts of streptomycin (300 micrograms) and gentamicin (120 micrograms) were established for E. faecalis ATCC 29212; zone limits are 16 to 22 mm for gentamicin and 14 to 19 mm for streptomycin. No zones for inhibition were seen when E. faecalis ATCC 51299 was tested with these high-content disks.

Aminoglycosides↗
PubMed1975

Radiochromatographic quality control: a simplified system.

A simple means of graphically displaying the degree of radiocompound binding purity using a shielded G-M tube integrated with a rate metar and strip cahrt recorder is described. The instrument produces a permanent quality-control record and eliminates time-consuming radio-chromatographic segment counting.

Chromatography, Paper↗
PubMed2001

Sequence verification as quality-control step for production of cDNA microarrays.

To generate cDNA arrays in our core laboratory, we amplified about 2300 PCR products from a human, sequence-verified cDNA clone library. As a quality-control step, we sequenced the PCR products immediately before printing. The sequence information was used to search the GenBank database to confirm the identities. Although these clones were previously sequence verified by the company, we found that only 79% of the clones matched the original database after handling. Our experience strongly indicates the necessity to sequence verify the clones at the final stage before printing on microarray slides and to modify the gene list accordingly.

Gene Library↗
PubMed1995

[Quality control of the micro-ELISA technic applied to the diagnosis of human and canine visceral leishmaniasis].

Visceral leishmaniasis (VL) or kala-azar is, in Portugal, a zoonosis with the dog as reservoir. A quality control of the technique of micro-ELISA was carried out, using as reference the technique of IFI, the most commonly used for the diagnosis of this protozoosis, both for human and canine sera. Three different methods were used to estimate the cut-off point: X + 2sd (average for negative sera plus two standard deviation), P/N and J index. As quality parameteres were used sensitivity, specificity, efficacy and positive predictive value. The cut-off point for human sera was established at 0.100 A, with 100% sensitivity, 90.5% specificity, 95.3% efficacy and 91.4% positive predictive value, and for canine sera in 0.200 A, with 80.0% sensitivity, 94.3% specificity, 87.7% efficacy and 96.6% positive predictive value. Reproducibility was not fully satisfactory and two different ways of improving it are proposed: P/N and a correction factor. A statistically significant correlation was observed between micro-ELISA's absorbances and IFI titres regarding human sera, though it was not possible to do the same for dog sera.

Animals↗
PubMed2003

Statistical and graphical methods for quality control determination of high-throughput screening data.

High-throughput screening (HTS) is used in modern drug discovery to screen hundreds of thousands to millions of compounds on selected protein targets. It is an industrial-scale process relying on sophisticated automation and state-of-the-art detection technologies. Quality control (QC) is an integral part of the process and is used to ensure good quality data and mini mize assay variability while maintaining assay sensitivity. The authors describe new QC methods and show numerous real examples from their biologist-friendly Stat Server HTS application, a custom-developed software tool built from the commercially available S-PLUS and Stat Server statistical analysis and server software. This system remotely processes HTS data using powerful and sophisticated statistical methodology but insulates users from the technical details by outputting results in a variety of readily interpretable graphs and tables. It allows users to visualize HTS data and examine assay performance during the HTS campaign to quickly react to or avoid quality problems.

Computer Graphics↗
PubMed1993

Studies of quality control of 99mTc-labelled macroaggregated albumin--Part 1. Aggregation of non-mercaptalbumin and its conformation.

The aggregative condition of albumin was investigated using bovine serum albumin (BSA) as a model for quality control of 99mTc-macroaggregated albumin (99mTc-MAA). Uniformalized aggregates were obtained from the oxidized non-mercapt-type of BSA by heating. The size of the aggregates was affected by the pH and the types of buffer solutions used as well as the concentrations of albumin and buffers. The beta form structure of the albumin was more stable on heating and this may contribute to its aggregation. Aggregation of oxidized non-mercaptalbumin afforded a portion of smaller sized particles in MAA, this being an inappropriate factor for scintiscanning of lungs. Our results suggest that it is necessary to remove oxidized type albumin from human serum albumin as the starting material, in order to prepare MAA with a uniform and larger particle size.

Albumins↗
PubMedDate not supplied

[The quality control of a photoprotector bag against ultraviolet light].

The action of light on parenteral nutritional solutions may affect the stability of many of their ingredients. The aim of this study is to perform quality controls on a commercial photoprotective bag by quantifying the degradation of riboflavin in isotonic saline solution during forty-eight hours. Thirty solutions were prepared using 5 mg of riboflavin in 500 ml of saline solution. These were divided into three batches; one not protected from the light, one in a black bag and the third in a commercial bag. Samples were taken at 0 and 48 hours, and were analyzed by spectrophotometry. Solutions were prepared using 1.75 mg of riboflavin in 500 ml of saline solution. The same method was followed, and the samples were analyzed by fluorometry. The results were analyzed using the Student t test. The black bag was seen to be superior to the other two as a protector against ultraviolet light. There were no significant differences between the commercial bag and the non-protective bag.

Evaluation Studies as Topic↗
PubMed1993

The applicability of the cumulative embryo score system for embryo selection and quality control in an in-vitro fertilization/embryo transfer programme.

The cumulative embryo score system involves three aspects of relevance in pregnancy achievement during in-vitro fertilization (IVF) and embryo transfer: cleavage rates, morphological qualities and the number of embryos transferred. The scores of 602 IVF/embryo transfer trials were calculated and analysed to determine the system's relationship to pregnancy rate, pregnancy outcome and the incidence of twin and triplet pregnancies. The system was also applied to cycles where endotoxins were either present in or absent from culture medium, in order to evaluate its validity in quality control analyses. Pregnancy rates were found to increase from 4%, with scores between 1 and 10, to 35% in the 41-50 group. The score of 20 was the criterion for separating patients into poor and good pregnancy prognosis groups (P = 0.00001). Biochemical abortions occurred more frequently with scores < 20 (P = 0.00978), but a similar relationship was not found in clinical abortion rates (P = 0.62206). Birth rates below and above a score of 20 (2.8 and 19.2%, respectively) differed significantly (P = 0.0005). The scores of twins overlapped extensively with those of singleton births, but those of all triplets were > 40. The system did not reflect a correlation between embryo quality and the presence of endotoxins in culture medium.

Culture Techniques↗
PubMed1982

A quality control study to assess the inter-laboratory variability of routine estrogen and progesterone receptor assays.

The steroid hormone receptor laboratories of Bern, Basel, Zürich, Locarno, Lausanne and Geneva have participated in a quality control study to assess potential inter-laboratory variability in results of tests for determination of steroid hormone receptor status in human breast tumor biopsies. Homogeneous breast tumor powders containing low, medium and high concentrations of estrogen receptors (ER) and progesterone receptors (PR) were prepared in Bern and dispatched on solid CO2 to each laboratory within 1 day of preparation. Each laboratory was requested to assay each powder for ER and PR by their usual procedures. The results revealed that the quantitative discrepancies in ER and PR binding values among the participants could be attributed in part to variations in the methods used for measuring cytosol protein content and also to the differences in hormone receptor assay methods. Nevertheless, all of the laboratories were able to identify the samples containing low, medium and high concentrations of ER and PR.

Breast Neoplasms↗
PubMed1995

Quality control guidelines for National Committee for Clinical Laboratory Standards recommended broth macrodilution testing of amphotericin B, fluconazole, and flucytosine.

Amphotericin B, fluconazole, and flucytosine (5FC) were tested in a multilaboratory study to establish quality control (QC) guidelines for yeast antifungal susceptibility testing. Ten candidate QC strains were tested in accordance with National Committee for Clinical Laboratory Standards M27-P guidelines against the three antifungal agents in each of six laboratories. Each laboratory was assigned a unique lot of RPMI 1640 broth medium as well as a lot of RPMI 1640 common to all of the laboratories. The candidate QC strains were tested 20 times each against the three antifungal agents in both unique and common lots of RPMI 1640. A minimum of 220 MICs per drug per organism were generated during the study. Overall, 95% of the MICs of amphotericin B, fluconazole, and 5FC fell within the desired 3 log2-dilution range (mode +/- 1 log2 dilution). Excellent performance with all three drugs was observed for Candida parapsilosis ATCC 22019 and C. krusei ATCC 6258. With these strains, on-scale 3 log2-dilution ranges encompassing 96 to 99% of the MICs of all three drugs were established. These two strains are recommended for QC testing of amphotericin B, fluconazole, and 5FC. Reference ranges were also established for an additional four strains for use in method development and for training. Four strains failed to perform adequately for recommendation as either QC or reference strains.

Amphotericin B↗
PubMed2001

Use of similarity measures for quality control of benthic diatom samples.

A method for evaluating the similarity of replicate benthic diatom samples based on the Bray-Curtis similarity measure is described. This technique may be useful as part of quality control procedures where objective performance measures are required. Levels of similarity > 60% typically indicate good agreement between the primary analyst and auditor. However, an evaluation of 57 comparisons indicated that achievable levels of similarity were dependent upon the species diversity of the sample, with samples with high species diversity typically having lower levels of similarity than samples with low species diversity. Whilst a threshold value of 60% is adequate for most samples, a stiffer threshold of 70% should be applied to samples with very low levels of diversity.

Diatoms↗
PubMed2001

[Statistical quality control of clinical laboratory analyses using Chi squared criterion (use of computer modeling)].

Models of analytical series simulating good results and series with systematic errors were created on the basis of data bank of results of clinical biochemical analyses by computer simulation method. The quality of analyses was evaluated using chi 2 test. This parameter reacts to slight systematic errors and depends little on changes in the examined patient population; on the other hand, its sensitivity is the higher the longer is the analytical series. Statistical method for quality control by the chi 2 test is highly sensitive, absolutely objective, and requires no extra expenses for control studies.

Chi-Square Distribution↗
PubMed1993

Automatic film processors' quality control test in Greek military hospitals.

The two major military radiology installations (Athens, Greece) using a total of 15 automatic film processors were assessed using the 21-step-wedge method. The results of quality control in all these processors are presented. The parameters measured under actual working conditions were base and fog, contrast and speed. Base and fog as well as speed displayed large variations with average values generally higher than acceptable, whilst contrast displayed greater stability. Developer temperature was measured daily during the test and was found to be outside the film manufacturers' recommended limits in nine of the 15 processors. In only one processor did film passing time vary on an every day basis and this was due to maloperation. Developer pH test was not part of the daily monitoring service being performed every 5 days for each film processor and found to be in the range 9-12; 10 of the 15 processors presented pH values outside the limits specified by the film manufacturers.

Calibration↗