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PubMed2001

Quality control in mutation analysis: the European Molecular Genetics Quality Network (EMQN).

UNLABELLED: The demand for clinical molecular genetics testing has steadily grown since its introduction in the 1980s. In order to reach and maintain the agreed quality standards of laboratory medicine, the same internal and external quality assurance (IQA/EQA) criteria have to be applied as for "conventional" clinical chemistry or pathology. In 1996 the European Molecular Genetics Quality Network (EMQN) was established in order to spread QA standards across Europe and to harmonise the existing national activities. EMQN is operated by a central co-ordinator and 17 national partners from 15 EU countries; since 1998 it is being funded by the EU commission for a 3-year period. EMQN promotes QA by two tools: by providing disease-specific best practice meetings (BPM) and EQA schemes. A typical BPM is focussed on one disease or group of related disorders. International experts report on the latest news of gene characterisation and function and the state-of-the-art techniques for mutation detection. Disease-specific EQA schemes are provided by experts in the field. DNA samples are sent out together with mock clinical referrals and a diagnostic question is asked. Written reports must be returned which are marked for genotyping and interpretation. So far, three BPMs have been held and six EQA schemes are in operation at various stages. Although mutation types and diagnostic techniques varied considerably between schemes, the overall technical performance showed a high diagnostic standard. Nevertheless, serious genotyping errors have been occurred in some schemes which underline the necessity of quality assurance efforts. CONCLUSION: The European Molecular Genetics Quality Network provides a necessary platform for the internal and external quality assurance of molecular genetic testing.

Benchmarking↗
PubMed1985

Effects of varying dilutions of quality control sera on precision of analytes.

Precisions obtained during an "unknown" quality control program using lyophilized serum reconstituted with varying amounts of diluent were compared with precisions achieved with the manufacturer's recommended dilution for 23 commonly measured analytes, including enzymes and radioimmunoassays, for four laboratories over two years. Except for bilirubin and possibly calcium and alkaline phosphatase, no tendency to deterioration of precision was observed as a result of varying the volume of diluent. The range of dilutions was from 92% to 108% of the recommended volume.

Alkaline Phosphatase↗
PubMed2006

[Does internal quality control reduce mistakes and complications? A plea for structured surgical education and increased transparency in clinical day-to-day work].

Quality control in most surgical departments shows major deficiencies. Only 50% have daily conferences on the surgical indication, and morbidity and mortality conferences are held in less than 20% of the institutions. However, pre-, intra- and postoperative quality control may be able to reduce mistakes and complications. Among others, the possibilities to reduce perioperative morbidity and mortality include preoperatively an early evaluation of the patient in the outpatient-clinic, intraoperatively a structured and didactic teaching of the surgical trainee and postoperatively a morbidity and mortality conference. In particular the latter one may promote surgical training and may increase transparency of the perioperative results. The delicate nature of morbidity and mortality conferences can be overcome in an atmosphere of mutual respect and personal honesty.

Attitude of Health Personnel↗
PubMed1993

DNA flow cytometry measurements as surrogate endpoints in chemoprevention trials: clinical, biological, and quality control considerations.

DNA flow cytometric evaluation of S-phase fraction (SPF) is a strong and consistent predictor of relapse-free survival in the node-negative breast cancer patient. As such, it can be implicated as a marker of tumor aggressiveness and has been shown to be an independent predictor of outcome in a multivariate setting. Measurement of ploidy status is less well-defined as a marker of prognosis, but may be an important marker of response to therapy. Estimation of DNA ploidy and proliferative capacity by flow cytometry can be obtained from virtually any type of specimen, including fine needle aspirates, fresh or frozen material, as well as formalin-fixed, paraffin-embedded material, as long as there is a sufficient number of tumor nuclei for assay. Therefore, the assay has clinical relevance in predicting relapse, as well as providing flexibility for sample preparation. In addition, flow cytometric measurements are biologically relevant markers. In general, DNA index is a good estimate of total chromosome number. SPF, using sophisticated modeling algorithms, shows good correlation with thymidine labeling index and/or bromodeoxyuridine incorporation, two standard assays used to measure DNA synthesis in fresh tissue. Recently, preliminary data in locally advanced breast cancer have indicated that ploidy and/or S-phase may also be useful in predicting cellular response to chemotherapy. Although there is good justification for measuring these parameters, appropriate quality control and quality assurance measures must be incorporated into all aspects of the assay--from sample handling and preparation to interpretation of cell cycle and histogram data.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Neoplasms↗
PubMed1990

Engineered human antibodies as immunologic quality control reagents.

This study demonstrates the utility of a panel of genetically-engineered human-mouse chimeric antibodies with variable region specificity for a hapten, NP, and constant regions analogous to the different human immunoglobulin isotypes as quality control reagents. They performed well as isotype-restricted human immunoglobulin proteins to test the specificity to total serum Ig immunoenzymetric assays and as antibodies to validate selected conjugated reagents used in human antibody immunoassays. The chimeric antibodies studied have several advantages over human paraproteins as quality control reagents for clinical assays. They possess single isotypes, are free of other human immunoglobulin isotypes, can be produced in large quantities in cell culture, and have a defined specificity for NP, an antigen that can be conjugated to BSA and isolubilized on most solid phase surfaces.

Animals↗
PubMed1989

Quality control in the IVF laboratory: in-vitro and in-vivo development of mouse embryos is unaffected by the quality of water used in culture media.

We have examined the effect of media made with tap water or with various purified waters on the fertilization of mouse oocytes, their development to blastocysts, their rate of hatching in vitro and their survival after transfer to recipients. Zona-intact and zona-free embryos, as well as cell clusters from 8-cell stage embryos, were also used. The macromolecular composition of the media was varied. We were unable to find any adverse effect of tap water under any condition examined. The implications of these findings for quality control in IVF units are discussed.

Animals↗
PubMed1998

KLT-based quality controlled compression of single-lead ECG.

An electrocardiogram (ECG) compression algorithm based on a combination of the Karhunen-Loeve transform (KLT) and multirate sampling is introduced. The use of multirate sampling reduces KLT computational times to those reported for wavelet-packet-based compression techniques. A beat-by-beat quality controlled compression criterion is shown to be necessary to ensure clinically adequate reconstruction of each beat. The resulting quality controlled algorithm efficiently achieves compression rates of approximately 30-40:1 for the MIT-BIH database.

Algorithms↗
PubMed1987

Acceptance testing and quality control of gamma cameras, including SPECT.

The measurement of several performance parameters of a scintillation camera at the time of installation and thereafter at regular intervals is necessary to ensure that the camera is operating within specifications and to detect changes over time that can initiate a request for service. There are varied opinions on what constitutes a satisfactory acceptance test and quality control program. Few individuals would disagree that either an acceptance test or routine quality control measurements are necessary, yet agreement on the contents and frequencies of these tests is lacking. This paper discusses the performance parameters of scintillation cameras that are usually measured for planar imaging and also for SPECT with rotating cameras.

Quality Control↗
PubMed2003

A disposable microbial based biosensor for quality control in milk.

The food industry needs suitable analytical methods for quality control, that is, methods that are rapid, reliable, specific and cost-effective as current wet chemistries and analytical practices are time consuming and may require highly skilled labor and expensive equipment. The need arises from heightened consumer concern about food composition and safety. The present study was carried out keeping in view the recently emerging concern of the presence of urea in milk, called "synthetic milk". The biocomponent part of the urea biosensor is an immobilized urease yielding bacterial cell biomass isolated from soil and is coupled to the ammonium ion selective electrode of a potentiometric transducer. The membrane potential of all types of potentiometric cell based probes is related to the activity of electrochemically detected product, and thus to the activity of the substrate by a form of the Nernst equation. Samples of milk were collected and analyzed for the presence of urea by the developed biosensor with a response time as low as 2 min. The results were in good correlation with the pure enzyme system.

Animals↗
PubMed2006

Precompression quality-control algorithm for JPEG 2000.

In this paper, a precompression quality-control algorithm is proposed. It can greatly reduce computational power of the embedded block coding (EBC) and memory requirement to buffer bit streams. By using the propagation property and the randomness property of the EBC algorithm, rate and distortion of coding passes is approximately predicted. Thus, the truncation points are chosen before actual coding by the entropy coder. Therefore, the computational power, which is measured with the number of contexts to be processed, is greatly reduced since most of the computations are skipped. The memory requirement, which is measured with the amount required to buffer bit streams, is also reduced since the skipped contexts do not generate bit streams. Experimental results show that the proposed algorithm reduces the computational power of the EBC by 80% on average at 0.8 bpp compared with the conventional postcompression rate-distortion optimization algorithm. Moreover, the memory requirement is also reduced by 90%. The average PSNR degrades only about 0.1-0.3 dB, on average.

Algorithms↗
PubMed1980

Quality control in therapeutic drug monitoring: intralaboratory precision and medical requirements.

Formal quality control procedures have become a part of the clinical laboratory. Application of these procedures to therapeutic drug monitoring, which has been introduced into the clinical laboratory relatively recently, is incomplete. Most attention has been directed toward questions of accuracy and laboratory-to-laboratory precision, particularly with respect to antiepileptic agents. Intralaboratory precision must be addressed first, since it is fundamental to accuracy and laboratory-to-laboratory variability and most patients are treated based on results generated by a single laboratory. Intralaboratory precision data were gathered from laboratories already offering therapeutic drug monitoring services. In addition, the intralaboratory precision demands of good medical management was gathered from physicians who use therapeutic drug monitoring services. For 20 specified drugs, most laboratories reported intralaboratory precision (relative standard deviations) of 10% or less. Managing physician responses demonstrated that most require precision of 10 to 15% or 20 to 25%. Individual laboratories should use these data as an indication of the level of intralaboratory precision that may be achieved and that is required. The state of the art of intralaboratory precision is acceptable relative to medical management, but may need improvement as it contributes to laboratory-to-laboratory variability.

Drug Therapy↗
PubMedDate not supplied

Interpretive criteria, quality control guidelines, and drug stability studies for susceptibility testing of cefotaxime, cefoxitin, ceftazidime, and cefuroxime against Neisseria gonorrhoeae.

Cefotaxime, cefoxitin, ceftazidime, and cefuroxime were tested in a multicenter study to establish susceptibility testing criteria and quality control guidelines for Neisseria gonorrhoeae. Interpretive criteria were established by using triplicate testing of at least 100 gonococcal strains having various susceptibility patterns to currently utilized drug regimens. Only a susceptible category was proposed for cefotaxime and ceftazidime (greater than or equal to 31 mm and less than or equal to 0.5 micrograms/ml) because of rare resistant isolates. The other interpretive crtieria were cefoxitin susceptible, greater than or equal to 28 mm (less than or equal to 2 micrograms/ml); intermediate, 24-27 mm (4 micrograms/ml), and resistant, less than or equal to 23 mm (greater than or equal to 8 micrograms/ml); cefuroxime-susceptible, greater than or equal to 31 mm (less than or equal to 1 micrograms/ml); moderately susceptible, 26-30 mm (2 micrograms/ml); and resistant, less than or equal to 25 mm (greater than or equal to 4 micrograms/ml). Quality control criteria were established by using multiple agar lots, three disk lots, and a number of replicates consistent with National Committee for Clinical Laboratory Standards M23-T guidelines.

Cefotaxime↗
PubMed2002

One hundred percent thorough quality control rescreening of liquid-based monolayers in cervicovaginal cytopathology.

BACKGROUND: Quality control (QC) of Papanicolaou (Pap) smear testing focuses on the identification of screening errors by 10% random, rapid, or thorough manual rescreening of some portion of negative smears. One hundred percent thorough manual rescreening has been reported to be the most effective method of identifying screening errors in conventional Pap smears (CP), but to the authors' knowledge no experience with this QC method has been reported for the ThinPrep Pap test (TP). The current study reports the estimated screening error rate of TP as determined by a QC program using 100% thorough rescreening. METHODS: All TP samples received at the study institution between January 1, 1999 and December 31, 2000 and initially screened as negative underwent thorough manual QC rescreening. RESULTS: A total of 53,419 TP samples were received during the study period. Of these, 5,368 cases (10%) initially were interpreted as abnormal. A total of 47,247 cases (88.4%) were rescreened. Abnormalities were identified in 804 additional cases, for a screening error rate of 13.0%. Of the 804 cases, 678 (84.3%) were atypical squamous cells of undetermined significance, 116 (14.4%) were low-grade squamous intraepithelial lesions, and 10 (1.2%) were high-grade squamous intraepithelial lesions. No tumors were identified on rescreening. CONCLUSIONS: In the current study, 100% thorough rescreening of TP samples was found to result in the detection of a significant number of abnormalities that would have been missed by routine random 10% QC rescreening. The screening error rate determined by 100% thorough QC rescreening of TP is comparable to that reported for CP QC rescreening.

Carcinoma, Squamous Cell↗
PubMed1980

[Quality control of Roentgen equipment with automatic exposure using a newly developed test phantom. Part II: surface dose, image parameters and quality number (author's transl)].

The article reproduces further results of quality control tests conducted with 42 automatically exposed roentgenographs of a test phantom, for the parameters surface dose (Do), film-distant (AF) and film-proximal (AN) resolution, optical density of dominant (SDom), film contrast (KF) and size of focus. By means of definition of the quality number z = AN x AF/log10 x Do, it is possible to state the sequence of qualitatively different X-ray films and to plot this against log10 t to take organ movements into consideration, thus supplying a simple criterion of the quality of Roentgen equipment. Good equipment will yield values of z/log10 t = 3, whereas medium-quality and insufficiently equipped apparatus will yield values around 2 or 1, respectively, or even below this figure. If the values are too low, analysis of all data obtained with the test phantom will supply indications with regard to the possible causes. Of the 42 X-ray films tested in this study, the z/log10 t values were above 2 in 15 cases, and below 2 in the same number of cases. Variations in the size of focus, optical density of dominant and contrast, are shown in the diagrams and described quantitatively by their average values anad standard errors.

Models, Structural↗
PubMed2006

Quality control metrics for LC-MS feature detection tools demonstrated on Saccharomyces cerevisiae proteomic profiles.

Quantitative proteomic profiling using liquid chromatography-mass spectrometry is emerging as an important tool for biomarker discovery, prompting development of algorithms for high-throughput peptide feature detection in complex samples. However, neither annotated standard data sets nor quality control metrics currently exist for assessing the validity of feature detection algorithms. We propose a quality control metric, Mass Deviance, for assessing the accuracy of feature detection tools. Because the Mass Deviance metric is derived from the natural distribution of peptide masses, it is machine- and proteome-independent and enables assessment of feature detection tools in the absence of completely annotated data sets. We validate the use of Mass Deviance with a second, independent metric that is based on isotopic distributions, demonstrating that we can use Mass Deviance to identify aberrant features with high accuracy. We then demonstrate the use of independent metrics in tandem as a robust way to evaluate the performance of peptide feature detection algorithms. This work is done on complex LC-MS profiles of Saccharomyces cerevisiae which present a significant challenge to peptide feature detection algorithms.

Algorithms↗
PubMed1983

Multicenter evaluation of the proposed quality control limits and interpretive zone standards for in vitro susceptibility testing with norfloxacin.

A seven-center collaborative study was carried out to evaluate the in vitro performance of the 10 micrograms norfloxacin disks on the basis of previously proposed interpretive susceptibility zone standards and quality control parameters. Of 7,858 clinical isolates tested, 93.2, 4.9, and 1.9% fell into the susceptible, moderately susceptible, and resistant groups, respectively. The quality control data based on a total of 1,368 zone diameter measurements compared quite favorably with the proposed performance limits as follows: Escherichia coli ATCC 25922, 28 to 35 mm versus 28 to 36 mm; Staphylococcus aureus ATCC 25923, 21 to 29 mm versus 17 to 29 mm; and Pseudomonas aeruginosa ATCC 27853, 23 to 27 mm versus 22 to 29 mm.

Anti-Infective Agents↗