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Results for “Quality Control”

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PubMed2002

[Central inter-laboratory quality control for microscopic diagnosis of tuberculosis in Madagascar in 2000].

Since June 1997, a quarterly quality control of sputum smear exam for the tubercle diagnosis, depending on double reading of slides, was implemented between both central laboratories of the Mycobacteria National Reference Centre in Madagascar (mycobactoria laboratories of Institut Pasteur Madagascar [IPM] and Institut Hygiène Sociale [IHS]--Health Ministry). In 2000, four controls were done, in the course of which 240 slides were coloured by auramine, coming both from IPM and IHS, and another 80 slides from IHS were coloured by Ziehl-Neelsen. All the results were in agreement for the samples stained with auramine, while two false negatives were found for the samples stained with Ziehl-Neelsen. The maintenance of this quality control between the two laboratories is necessary to insure the reliability of their results and the controls that they make for the peripheral laboratories.

Bacteriological Techniques↗

PubMed1992

Quality control program of steroid receptor assays: an international study.

Lyophilized calf uterine cytosol standards were prepared for quality control of estrogen receptor (ER) determination, and lyophilized cytosols and tissue powders were used for quality control of progesterone receptor (PR) analysis. Two series of four samples were analyzed either for ER or PR contents, twice within one month, by 7 laboratories in 5 countries. Coefficient of variation (CV) of the between-laboratory averages assayed in a single run of ER-positive (ER+) and PR-positive (PR+) standards varied from 29.6 to 61.8% and from 32.4 to 76.2%, respectively. All laboratories, with the exception of a single value, could recognize samples of low, medium, an high ER level, as well as a negative sample. Most laboratories evaluated properly also the level of PR samples. The average between-laboratory CV values of protein determination in the relevant standards were 23%.

Animals↗

PubMed2006

Use of inert C&D materials for seawall foundation: quality control measures.

The technical viability of using inert construction and demolition (C&D) materials for the construction of seawall and breakwater foundations has been established by laboratory testing of the materials, numerical analysis of foundation stability, and a pilot field-scale engineering performance evaluation. However, quality control measures are still required so that only suitable materials are used for seawall and breakwater foundation construction. The development of different quality control measures for different site conditions is presented in this paper. The rationale, practicality, and implementation of these quality control measures are also discussed.

Conservation of Natural Resources↗

PubMedDate not supplied

Quality control of the autopap screening system employed as a primary screening device: rapid review of smears coded as no further review.

AIMS AND BACKGROUND: Automated reading of smears is increasingly used in cervical screening, and quality control procedures to check its performance are required. The aim of the present study was to evaluate the usefulness of rapid review of all smears coded as "no further review" (NFR) by the AutoPap system as a quality control procedure. METHODS: From 2002-2005, 153,269 smears were processed by AutoPap at the Centro per lo Studio e la Prevenzione Oncologica of Florence, Italy, and 24,503 (15.9%) were coded as NFR. All NFR smears underwent immediate rapid review by expert readers. RESULTS: Sixty-five of 118 NFR cases reviewed as ASCUS-R complied to recommended 6 months cytology, and 25 of 30 NFR cases reviewed as ASCUS-SIL or more severe accepted immediate colposcopy. As a result of such assessment, one single case of microinvasive carcinoma was detected in a woman aged 34 years: NFR smear had been reviewed as AGCUS, was followed by repeat AGCUS cytology and repeat negative colposcopy, and finally underwent conization. CONCLUSIONS: NFR report at AutoPap was associated with an extremely high negative predictive value, which might suggest using AutoPap as a primary screening tool, with NFR report prompting a "return to screening" recommendation. Rapid review of NFR smears is not recommended as a quality control measure for the negligible yield of high-grade lesions detected.

Adult↗

PubMed1985

Quality control of reflectometric determinations of glucose in dried blood spots on filter paper.

We evaluated the effect of sampling of capillary blood on filter paper on the later analysis for glucose. We found the method simple and reliable. Determination at the central laboratory of glucose in blood collected onto filter paper and comparison of the results with those obtained with test strips read in reflectometers at outpatient units is easy. Collecting duplicate samples on filter paper facilitates quality control by avoiding the complications that arise from using quality-control solutions that are not directly comparable with fresh blood, and it avoids the disturbances of test strip chemistry attributable to the glycolysis inhibitors added to blood samples intended for quality control.

Blood Glucose↗

PubMed1996

A quality control test for electronic portal imaging devices.

A quality control (QC) test suitable for routine daily use has been developed for video based electronic portal imaging devices. It provides an objective and quantitative test for acceptable image quality on the basis of the high contrast spatial resolution and the contrast-to-noise ratio (CNR). The test uses a phantom consisting of five sets of high-contrast rectangular bar patterns with spatial frequencies of 0.1, 0.2, 0.25, 0.4, and 0.75 lp/mm. Data obtained during a one month calibration period were used to determine a critical frequency fc for the relative square wave modulation transfer function and a critical contrast-to-noise ratio (CNRc). Subsequent measurements indicating significant deviations from these critical values result in warning messages to the operator indicating potential problems in system performance. Measurements over a period of two years show that the QC test provides a sensitive indication of imaging performance.

Biophysical Phenomena↗

PubMed2001

Manufacture and quality control of CAMPATH-1 antibodies for clinical trials.

BACKGROUND: CAMPATH-1 Abs have been used for T-cell depletion in stem-cell transplantation since the early 1980s. During that time there has been substantial progress in manufacturing techniques and quality control procedures. This article summarizes the methods used to produce the Abs for clinical use and describes results of quality control tests on representative batches. METHODS: Rat hybridoma and recombinant CHO cells were cultured in hollow-fiber fermentors. Antibodies were purified from the culture supernatant by fractionation with ammonium sulphate, or by column chromatography. Additional steps were added to assure the removal of DNA and viruses. A range of analytical methods was used to characterize the antibodies. Samples were stored frozen at -70 degrees C and re-analyzed many years later to assess the long-term stability. RESULTS: Hollow-fiber fermentors provided a simple and reliable means for antibody production, with yields between 3-10 mg/h and a convenient concentration for further processing (0.6-2.0 mg/mL). All of the CAMPATH-1 Abs (rat IgM, rat IgG2b and human IgG1) could be purified by affinity chromatography on Protein A, but the low pH required for elution caused unacceptable aggregation of the IgM. CAMPATH-1H contained approx. 20% dimeric IgG, which could be removed by size exclusion chromatography. Antibodies were stable for at least 6 years at -70 degrees C, but there was unacceptable aggregation of CAMPATH-1M in one batch stored for 9 years. DISCUSSION: Pilot-scale production of MAbs for clinical studies is feasible in a small academic center, but regulatory requirements now demand that great attention is paid to all aspects of manufacturing and quality assurance. Although the underlying principles of cell culture and protein chemistry remain the same, the level of documentation, validation and quality control has increased greatly over the last 20 years.

Alemtuzumab↗

PubMed1983

The first external quality control survey (EOCS) for antithyroglobulin- and antimicrosomal antibody determination.

Fourteen laboratories participated in an external quality control survey (EQCS) for antithyroglobulin- and antimicrosomal-antibody determination. Seventeen frozen serum samples from individuals suffering from various thyroid diseases were dispatched by mail. Different test systems were used by the participants including the haemagglutinatin test, radioimmunoassay (RIA), enzyme immunoassay (ELISA) and immunofluorescence test. The different test results of each participant were sized and could be compared by giving place numbers to each test result. Inter-laboratory quality control was performed by evaluation of a rank correlation coefficient. There was close agreement between the haemagglutination test results of antimicrosomal antibody determination with different test kits, and these tests showed good precision. Antithyroglobulin antibody titers from the two haemagglutination test-kits used, however, were not directly comparable. When sized by place numbers, antithyroglobulin antibody results from haemagglutinatin test, RIA and ELISA were in close agreement. The least correspondence was shown by the immunofluorescence test, in the antithyroglobulin antibody determination.

Antibodies↗

PubMedDate not supplied

Stat tests service and quality control at Hamad Medical Corporation Doha.

BACKGROUND: The recognition and validity of laboratory results can better be judged by its internal and external quality control systems. Here we report an internal quality check of the stat service provided to the inpatients at Hamad Medical Corporation, Doha, State of Qatar. METHODS: Periodic internal quality control of nine chemistry analytes, BUN, Na, K, Cl, Ca, Co2, Glucose, Creatinine and Bilirubin were made on auto-analyzer Astra VIII. BIORAD Normal and Abnormal (Chemistry Control) and immunoassay level 1, 2 and 3 were employed. All results falling with in 2 SD were accepted. RESULTS: 2 SD% for chemistry Normal and Abnormal ranged from 61.5% to 85.5% and 92.0% to 98.8% and for hormones Immunoassay level 1, 2, and 3 from 92.7% to 100% respectively.

Blood Chemical Analysis↗

PubMed2001

Immunolocalization of UDP-glucose:glycoprotein glucosyltransferase indicates involvement of pre-Golgi intermediates in protein quality control.

The UDP-glucose:glycoprotein glucosyltransferase (GT) is a protein folding sensor and glycosyltransferase that constitutes an important component of the protein quality control machinery. With the use of quantitative immunogold electron microscopy, we established the subcellular distribution of GT in rat liver and pancreas and Drosophila melanogaster salivary gland as well as cell lines and correlated it with that of glucosidase II, calreticulin, and pre-Golgi intermediate markers. Labeling for GT, as well as for glucosidase II and calreticulin, was found in the endoplasmic reticulum (ER), including nuclear envelope and pre-Golgi intermediates located between ER and Golgi apparatus, and in the cell periphery. In the rough ER, labeling for GT was inhomogeneous, with variously sized labeled and unlabeled cisternal regions alternating, indicative of a meshwork of quality control checkpoints. Notably, labeling intensity for GT was highest in pre-Golgi intermediates, corresponding to twice that of rough ER, whereas the Golgi apparatus exhibited no specific labeling. These results suggest that protein quality control is not restricted to the ER and that the pre-Golgi intermediates, by virtue of the presence of GT, glucosidase II, and calreticulin, are involved in this fundamental cellular process.

Animals↗

PubMed1974

Automated quality control for the haematology laboratory.

Two simple methods of using sophisticated statistical techniques to analyse intralaboratory quality control data are described. One method uses a plastic grid to assess the cumulative sum (cusum) graph. An equivalent procedure, which may be carried out by a laboratory computer, gives automated on-line quality control of the Coulter S blood counter. The possible development of simple apparatus to carry out the same function is discussed.

Automation↗

PubMed1996

Constructing a therapist-driven protocol. Spectrum of types and quality control.

Therapist-driven protocols for the implementation and delivery of respiratory care must be tailored to fit the needs of the individual institution. The method that is chosen for constructing a therapist-driven protocol depends on the type of protocol desired (disease-, symptom-, or treatment-based) and on whether a narrative or flow-diagram format is preferred. Because the goal of therapist-driven protocols is to provide a systematic method for determining appropriate respiratory care, quality control measures are necessary to ensure that desired outcomes are achieved. Quality control monitoring can be performed through the use of case-study exercises, verbal shift reports, and care-plan audits. Results of quality control monitoring techniques can be used to guide modification of protocols.

Clinical Protocols↗

PubMed2005

Quality control of slope-intercept measurements of glomerular filtration rate using single-sample estimates.

OBJECTIVES: Measurement of glomerular filtration rate (GFR) using the slope-intercept technique determines the plasma clearance curve by fitting a straight line to the logarithm of sample count rate. When two samples are used there is no check on the validity of curve fitting. GFR may also be estimated from single-sample concentrations. This study describes a method of quality control for the two-sample technique using the agreement between the one-sample and two-sample estimates. METHODS: GFR measurements using Tc-DTPA were performed on 225 adults and 100 children using two samples taken between 2 h and 4 h post-injection. The two-sample values obtained using the British Nuclear Medicine Guidelines slope-intercept technique were compared to one-sample estimates obtained using a new general equation. Equations describing the variation of GFR error with GFR value were defined. These were used to determine action levels giving the limits of expected agreement between slope-intercept and single-sample values. The use of these action levels for quality control was demonstrated in a further 120 GFR measurements. RESULTS: The variation of single-sample error estimate with GFR depended both on the time of sample and body surface area. For specific sample groups, the error variation with GFR could be approximated using a truncated quadratic equation. Four studies were identified as failing quality control in the dataset used to define the error equations. Two studies failed in the test dataset. CONCLUSIONS: One-sample equations give reliable estimates of GFR, which may be used for quality control of slope-intercept GFR assessment.

Adult↗

PubMed1996

Dual X-ray absorptiometry quality control: comparison of visual examination and process-control charts.

Dual X-ray absorptiometry (DXA) is widely used to monitor treatment efficacy in reducing the rate of bone mineral loss. In order to assure the validity of these measurements, instrument quality control of the DXA scanners becomes very important. This paper compares five quality control procedures (visual inspection, Shewhart chart with sensitizing rules, Shewhart chart with sensitizing rules and a filter for clinically insignificant mean changes, moving average chart and standard deviation, and cumulative sum chart [CUSUM]) in their ability to identify scanner malfunction by means of (1) an analysis of five longitudinal phantom data sets that had been collected during a clinical trial and (2) an analysis of simulated data sets. The visual inspection method is relatively subjective and depends on the operator's experience and attention. The regular Shewhart chart with sensitizing rules has a high false alarm rate. The Shewhart chart with sensitizing rules and an additional filter for clinically insignificant mean changes has the lowest false alarm rate but a relatively low sensitivity. The CUSUM method has good sensitivity and a low false alarm rate. In addition, this method provides an estimate of the date a change in the DXA scanner performance might have occurred. The method combining a moving average chart and a moving standard deviation chart came closest to the performance of the CUSUM method. Comparing the advantages and disadvantages of all methods, we propose the use of the CUSUM method as a quality control procedure for monitoring DXA scanner performance. For clinical trials use of the more intuitive Shewhart charts may be acceptable at the individual sites provided their scanner performance is followed up by CUSUM analysis at a central quality assurance center.

Absorptiometry, Photon↗

PubMed2026

plinkQC: an integrated tool for ancestry inference, sample selection, and quality control in population genetics.

MOTIVATION: Population genetic analyses rely on high quality datasets that pass rigorous controls for sample and marker quality. Many analyses also require additional processing including identification of ancestry and sample relatedness. A software package that addresses all these common, yet crucial tasks is missing. RESULTS: We have developed plinkQC, an R/CRAN package that combines these functionalities into a single software package with detailed vignettes for example applications. plinkQC determines the ancestry of study samples via a pre-trained random forest classifier that reaches 98% performance accuracy with just 5% of marker overlap between reference and user data. To obtain the maximal set of unrelated study samples, we developed a graph-based pruning method, taking both relationship estimates and sample quality into account. We demonstrate optimal sample selection on the 1000 Genomes project, where we retain an additional 71 samples compared to publicly available exclusion lists. Finally, plinkQC bundles these results together with per-individual and per-marker quality control checks into three simple functions and returns both the quality controlled dataset and quality control report about each step of the analysis. AVAILABILITY AND IMPLEMENTATION: plinkQC is available as an R/CRAN package. The documentation and code are available on github: https://meyer-lab-cshl.github.io/plinkQC/ and https://github.com/meyer-lab-cshl/plinkQC_manuscript.

Software↗

PubMed1987

Report on a joint European quality control survey for neonatal thyrotropin determinations (1986).

This paper presents the results of a joint European external quality control survey for thyrotropin determinations in blood dried on filter paper, carried out in 1986 in cooperation with several national quality control organizations. For the evaluation, 124 participants presented their individual diagnostic classifications in addition to their analytical results. Although, in relation to earlier studies of this kind, there was a significant improvement in interlaboratory precision the results still showed variance which depended on the analytical method and, possibly on the country in which it was performed. Regional differences were also evident in the diagnostic classifications.

Europe↗

PubMed1989

Quality control procedures in positron tomography.

The derivation of physiological parameters in positron tomography relies on accurate calibration of the tomograph. Normally, the calibration relates image pixel count density to the count rate from an external blood counter per unit activity concentration in each device. The quality control of the latter is simple and relies on detector stability assessed by measurement of a standard source of similar geometry to a blood sample. The quality control of the tomographic data depends on (i) detector stability, (ii) uniformity of calibration and normalisation sources and (iii) reproducibility of the attenuation correction procedure. A quality control procedure has been developed for an 8 detector ring (15 transaxial plane) tomograph in which detector response is assessed by acquiring data from retractable transmission ring sources. These are scanned daily and a print out of detector efficiencies is produced as well as changes from a given date. This provides the raw data from which decisions on recalibration or renormalization are made.

Quality Control↗

PubMed1991

Use of quality control standards in clinical flow cytometry.

Flow cytometry is important in the clinical laboratory, especially in hematology and cancer diagnosis. With newer applications being continuously developed clinicians who will use the results and laboratory staff who produce them should be aware of the instrumental quality control procedures required. This will allow evaluation of the reliability as well as the comparison of results between different laboratories. While information about sample preparation as well as staining procedures is easily available, information about instrumental quality control procedures is less so. Various standards and controls are available commercially and their correct choice and usage requires an understanding of the methodology of instrumental quality control. Methods to evaluate the precision, sensitivity and accuracy of measurements are discussed. Most laboratories report immunophenotyping data as the percentage of antibody positive cells and make no attempt to quantitate the amount of antibody binding per cell. Methods for quantitating the number of bound antibody molecules per cell along with a simple technique to compare results between laboratories are discussed. These techniques should encourage laboratory staff and clinicians to standardise methodology and to exchange patient data between laboratories.

Flow Cytometry↗