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At least 415 records · Page 23Linked to original sources
PubMed2003

Measurement of urinary porphyrins and porphyrin precursors in Dutch hospital laboratories: a review of quality control over 5 years.

BACKGROUND: We evaluated a quality control scheme for the measurement of urinary uroporphyrin, coproporphyrin, total urinary porphyrins and precursors of urinary porphyrins, delta-aminolevulinic acid and porphobilinogen that was performed in The Netherlands during a period of 5 years. METHODS: Six quality control samples were distributed each year to the participating laboratories. Mean concentrations and the corresponding coefficients of variation were calculated. RESULTS: Coefficients of variation varied widely and were very high in the concentration ranges that can be found in patients with low-grade porphyria. CONCLUSION: Commutable calibrators are needed to improve the laboratory diagnosis of porphyria.

Aminolevulinic Acid↗
PubMed1983

The impact of surgical quality control in multi-institutional group trials involving adjuvant cancer treatments.

Quality control involving surgical treatment in multi-institutional cancer trials is important because the results of postoperative adjuvant therapy might be obscured by inadequate surgery or pathologic examination of the specimen. In 1975, the Southeastern Cancer Study Group (SEG) initiated a randomized clinical trial of adjuvant immunotherapy (Corynebacterium parvum vs. bacillus Calmette-Guerin) in melanoma patients with nodal metastases. During the course of reviewing the results several years later, 20 of 136 patients (15%) entered into this study were judged as surgically ineligible. The reasons were: 1) biopsy of a metastatic node only without any subsequent regional lymph node dissection (12 patients), 2) partial lymph node dissection (six patients), or 3) too few nodes surgically removed or pathologically identified in the specimen (six patients). All 20 patients were entered into the study by medical oncologists. Thirteen of these 20 surgically ineligible patients have relapsed so far; many were taken off the study as "immunotherapy failures," when, in fact, they were surgical failures. Compared to the 116 surgically eligible patients, the 20 ineligible patients had a shorter median survival (4 months vs. 25 months) and a lower 1-year disease-free survival rate (36% vs. 62%, p = 0.01). The two groups were balanced equally with respect to prognostic factors. Because of these findings, minimum surgical and pathologic guidelines were established for each adjuvant therapy protocol in the SEG. Surgical quality control was reviewed by a surgeon in each institution prior to randomization and again by a surgical investigator centrally. Pathologic criteria were also defined more precisely. The problems with surgically ineligible patients have since been virtually eliminated. Quality control measures for surgical patients entered into cooperative group trials is an essential part of the protocol design and data review. In order to evaluate properly the impact of adjuvant therapy, each clinical trial must comprise a uniform group of surgically treated patients.

Biopsy↗
PubMed1996

Quality control during carotid endarterectomy.

Although some form of quality control assessment is standard practice following virtually all forms of peripheral vascular reconstruction, it is seldom applied to carotid endarterectomy. This is despite the fact that the complications following endarterectomy can be catastrophic, are often related to technical error and are not easily remedied. A number of novel quality control techniques are now available. This review article summarizes the application of these methods to ensuring optimal surgical practice in patients undergoing carotid endarterectomy.

Angioscopy↗
PubMed2000

A continuous quality control program for strict sperm morphology.

OBJECTIVE: To develop a training program with intervals of continuous quality control assessments for the evaluation of strict sperm morphology. DESIGN: Prospective analytical study. SETTING: Academic hospital and academic institution setting. PATIENT(S): Healthy sperm donors. INTERVENTION(S): Nine individual andrology laboratories in Switzerland were invited to participate in a training course for strict sperm morphology, which was followed up every 3 months by a continuous quality control program. Each laboratory received six slides over a period of 9 months, during which time the results were forwarded to the reference laboratory. Papanicolaou stain sperm slides were prepared and shipped to participating laboratories every 3 months. MAIN OUTCOME MEASURE(S): Percentage of normal spermatozoa. RESULT(S): The mean (+/-SE) percentage of normal sperm reported by the reference laboratory compared with the participating laboratories for slides 1-6 were 11. 4 +/- 1.6 vs. 17.3 +/- 6 (P>.2), 6.0 +/- 1.3 vs. 8.6 +/- 2.5 (P>.2), 9.0 +/- 0 vs. 9.6 +/- 3 (P>.2), 1 +/- 0 vs. 1.2 +/- 0.2 (P>.2), 23.3 +/- 0.3 vs. 28.0 +/- 1.3 (P>.2), and 2.0 +/- 0 vs. 6.1 +/- 1.2 (P>.2), respectively. Technician proficiency was reported to differ by <10% from the reference laboratory in 94% of cases. CONCLUSION(S): The results illustrate that training and proficiency testing can be conducted on a national and international level with the support of a reference laboratory. Global quality control measurements in andrology laboratories should become mandatory, since these results indicate that continuous quality control for laboratory technicians can be successful.

Humans↗
PubMed1999

Measures of quality control in the German component of the EPIC study. European Prospective Investigation into Cancer and Nutrition.

Quality control is an indispensable part of quality assurance in any study, intending to ensure high standards during data acquisition. The aim of this paper is to describe the measures of quality control undertaken in the German EPIC study centers and to present selected results of these procedures (EPIC = European Prospective Investigation into Cancer and Nutrition). For all data assessment tools applied in the German EPIC study, procedures were developed to monitor both the personnel as well as the technical instruments. These procedures combined quantitative and qualitative measurements of quality control. Interviewer performance was evaluated through direct observation and rated according to an evaluation score. Blood pressure and anthropometric measurements were both controlled through direct observation of measurement procedures as well as through periodical technical control of measurement devices. Blood sampling procedures were directly monitored and subsequent handling of the probes tightly recorded, including information on time sequence of work-up and room temperature. With these diverse control measurements and the obtained rating of assessment procedures a broad pool of information has been made available to support a critical evaluation of the data obtained in the EPIC study centers in Heidelberg and Potsdam.

Cohort Studies↗
PubMed1988

Evaluation of the L5178Y mouse lymphoma cell mutagenesis assay: quality-control guidelines and response categories.

A data-based approach to formulating quality-control criteria for the mouse lymphoma cell forward mutation assay is described. Quality-control guidelines for solvent controls, positive controls, and compound-treated cultures were developed based on analysis of over 800 experiments. Frequency distributions of experimental parameters of control cultures, such as mutant frequencies, cloning efficiencies, and suspension growths, were examined. Cloning efficiency and relative total growth affected the variability only when the test chemical was highly toxic. This information was used to generate the quality-control criteria, which were applied to an experiment before it was evaluated for a response. The response categories for classifying the effect of test chemicals on the assay system are defined in terms of (1) the statistically significant differences in average mutant frequency between solvent control cultures and cultures exposed to a chemical and (2) the trend of the dose-related responses.

Animals↗
PubMed2005

Effectiveness of education and quality control work group focusing on nursing practices for prevention of ventilator-associated pneumonia.

OBJECTIVES: To evaluate the effectiveness of education and quality control work group focusing on nursing practices for prevention of ventilator-associated pneumonia (VAP). MATERIAL AND METHOD: A quasi-experimental study was performed to evaluate the effect of education and quality control work group on prevention of VAP by 18 nurses in the womens' medical ward, Surat Thani Hospital, Thailand. Pre-intervention nursing practices were observed in March, 2002, followed by interventions in April 2002 and two post-tests on nursing practices in May 2002 and July 2002. Interventions included education and quality control work group focusing on nursing practices on prevention of VAR Each observation period lasted for one month. Research instruments included a demographic data collection form, a quality control circle teaching plan, an evaluation manual and an observational recording form. RESULTS: After the intervention, significant improvement on nursing practices for prevention of VAP was observed in the first (60% vs. 85%; P<0.001) and the second month (60% vs. 91 %; P<0.001) post-intervention. Compliance to nursing practice guidelines among the participants were also increased in all practice categories (87% vs. 98%; P<0.001). CONCLUSION: The present study suggests the positive roles of education and quality control work group to improve nursing practices for preventions of VAP Additional studies are needed to examine the long-term effects of these interventions.

Adult↗
PubMed2001

Benchmarking to the world's best in mathematics. Quality control in curriculum and instruction among the top performers in the TIMSS.

UNLABELLED: This article describes the education quality control systems (for mathematics) used by those countries that performed best on the Third International Mathematics and Science Study (TIMSS). Enforced quality control measures are defined as "decision points"--where adherence to the curriculum and instruction system can be reinforced. Most decision points involve stakes for the student, teacher, or school. They involve potential consequences for failure to adhere to the system and to follow the program at a reasonable pace. Generally, countries with more decision points perform better on the TIMSS. When the number of decision points and TIMSS test scores are adjusted for country wealth, the relationship between the degree of (enforced) quality control and student achievement appears to be positive and exponential. CONCLUSION: The more (enforced) quality control measures employed in an education system, the greater is students' academic achievement.

Benchmarking↗
PubMedDate not supplied

Quality control for deglycerolized red blood cells.

A quality-control procedure to detect inadequately deglycerolized red blood cells is feasible, although the cost-effectiveness of routinely employing such a test needs to be considered by each individual blood bank. When the standard deglycerolizing protocol is meticulously followed by experienced personnel, the chances of an error that would result in inadequate deglycerolization are remote. The administration of cells with excess residual glycerol can result only in intravascular lysis of the infused cells. However, if a blood bank feels the need for a quality-control test for deglycerolized red blood cells, resuspending cells in 0.7% NaCl and estimating the per cent hemolysis using a color comparator is a simple and effective test.

Blood Preservation↗
PubMed2005

Use of an amorphous silicon electronic portal imaging device for multileaf collimator quality control and calibration.

Multileaf collimator (MLC) calibration and quality control is a time-consuming procedure typically involving the processing, scanning and analysis of films to measure leaf and collimator positions. Faster and more reliable calibration procedures are required for these tasks, especially with the introduction of intensity modulated radiotherapy which requires more frequent checking and finer positional leaf tolerances than previously. A routine quality control (QC) technique to measure MLC leaf bank gain and offset, as well as minor offsets (individual leaf position relative to a reference leaf), using an amorphous silicon electronic portal imaging device (EPID) has been developed. The technique also tests the calibration of the primary and back-up collimators. A detailed comparison between film and EPID measurements has been performed for six linear accelerators (linacs) equipped with MLC and amorphous silicon EPIDs. Measurements of field size from 4 to 24 cm with the EPID were systematically smaller than film measurements over all field sizes by 0.4 mm for leaves/back-up collimators and by 0.2 mm for conventional collimators. This effect is due to the gain calibration correction applied by the EPID, resulting in a 'flattening' of primary beam profiles. Linac dependent systematic differences of up to 0.5 mm in individual leaf/collimator positions were also found between EPID and film measurements due to the difference between the mechanical and radiation axes of rotation. When corrections for these systematic differences were applied, the residual random differences between EPID and film were 0.23 mm and 0.26 mm (1 standard deviation) for field size and individual leaf/back-up collimator position, respectively. Measured gains (over a distance of 220 mm) always agreed within 0.4 mm with a standard deviation of 0.17 mm. Minor offset measurements gave a mean agreement between EPID and film of 0.01+/-0.10 mm (1 standard deviation) after correction for the tilt of the EPID and small rotational misalignments between leaf banks and the back-up collimators used as a reference straight edge. Reproducibility of EPID measurements was found to be very high, with a standard deviation of <0.05 mm for field size and <0.1 mm for individual leaf/collimator positions for a 10x10 cm2 field. A standard set of QC images (three field sizes defined both by leaves only and collimators only) can be acquired in less than 20 min and analysed in 5 min.

Calibration↗
PubMed1995

Proposed quality control guidelines for antimicrobial susceptibility tests using tilmicosin.

Quality control guidelines for tilmicosin, a novel veterinary-use-only macrolide, were developed in a multi-laboratory study according to established National Committee for Clinical Laboratory Standards (NCCLS) procedures (M23-T2). Tilmicosin was incorporated into Sensititre plates for broth microdilution endpoint testing and into two lots of 15-micrograms disks for Kirby-Bauer agar disk diffusion testing. One common lot and five unique lots of Mueller-Hinton media were used. (Broth was cation adjusted, and agar was supplemented with 5% defibrinated sheep blood.) Bacteria used for reference strains included Pasteurella haemolytica 128K, Pasteurella multocida ATCC 43137, and Staphylococcus aureus ATCC 29213 (microdilution) and ATCC 25923 (disk). Replicate tests were conducted. Disk diffusion and broth microdilution quality control ranges are proposed.

Animals↗
PubMed2005

Protein chip for detection of different HCV antibodies: preparation, quality control, and clinical evaluation.

INTRODUCTION: As a contagious disease caused by hepatitis C virus (HCV) hepatitis C is a serious threat to human health. Therefore, the detection and verification of HCV infection is very important in the treatment of hepatitis C. This study investigated the preparation, quality control, and clinical evaluation of a protein chip capable of simultaneously detecting different HCV antibodies. The aim was to establish a convenient method for the detection of HCV. METHOD: To prepare the protein chip, six antigens including five recombinant HCV antigens (chimeric, core, NS3, NS4, and NS5) and interleukin (IL)-1 were arrayed onto aldehyde-coated slides and blocked using 10% calf serum in phosphate buffered saline. After dilution with sample solution, the serum sample was added to a reaction well on the protein chip. After incubation for 30 minutes at 37 degrees C, fluorescence Cy3-labeled rabbit antihuman IgG was added and incubated again for 30 minutes at 37 degrees C, and then scanned. Positive or negative controls were established from serum samples with or without HCV infection. Clinical evaluation was done by detecting 490 serum samples using the protein chips and ELISA reagents, with 150 of the 490 serum samples confirmed by recombinant immunoblot assay (RIBA). RESULTS: The protein chip for detection of five HCV antibodies was successfully prepared. Fifteen positive controls and 15 negative controls were established as standard samples for quality control. The quality control-passed protein chip was tested again using the standard of the National Institute for the Control of Pharmaceutical and Biological Products (NICPBP), and met the quality control criteria prescribed by the NICPBP. In the clinical evaluation with 490 samples, the coincidence rates between the protein-chip assay and ELISA were 97.4% for positive and 100% for negative results. Five inconsistent samples that were positive in ELISA, but non-positive (four samples) or negative (one) in the protein-chip assay, were confirmed by RIBA (gold standard) to be four non-positive and one negative. The results of 150 samples showed the coincidence rates between protein chip and RIBA were 98.15% for positive and 96.88% for single-segment positive. CONCLUSION: The protein-chip assay has higher sensitivity and specificity than ELISA and has a high coincidence rate with RIBA. The protein chip, characterized by its easy operation and low economic cost, will be very useful for in vitro detection of HCV antibodies.

Hepacivirus↗
PubMed1996

Evaluation of protein containing quality control materials for blood gas analysis.

Protein containing quality control (QC) material in ampoules for blood gas, pH and electrolyte analysers has been manufactured using buffered protein (Bovine Serum Albumine, BSA) solution with sodium bicarbonate and chloride salts. For comparison a similar QC material but without protein was manufactured. Results obtained with ampouled QC material depend on pre-analytical effects, on matrix effects and on the stability of the material. Pre-analytical variation occurs with closed and/or opened ampoules. The shaking rate of the ampoule must be high (vortexing) and the duration of shaking long enough (15 seconds) to give good reproducibility. Temperature coefficients of protein containing controls are equal to those of protein free controls when incubated at different temperatures. Vigorously shaking of the ampoule gives a protein foam layer resulting in stable values for pH, pCO2 and pO2 during maximally 6 minutes after opening of the ampoule. Concerning matrix effects the CO2 buffer capacity of protein containing QC material is slightly higher compared to that of protein free QC materials as determined by tonometry with CO2/air gas mixtures and measuring pH and plotting log pCO2 vs. pH. The O2 buffer capacity measured as the bias on a properly functioning blood gas analyser is smaller than the bias of protein free QC material. The protein containing quality control is stable for at least 12 months when stored refrigerated at 2-6 degrees C and 28 days at room temperature.

Acid-Base Equilibrium↗
PubMed2001

Quality control for nucleic acid tests: common ground and special issues.

Traditional clinical laboratory quality control practices are being applied to new technologies for the detection and quantitation of nucleic acids in clinical samples, often with limited knowledge of the probability for clinically significant error detection or for false run rejection of such practices. This article reviews traditional quality control practices, discusses the possibilities for a more rational approach to quality control for nucleic acid tests and suggests some steps that can lead to quality improvement for these tests.

Clinical Laboratory Techniques↗
PubMed2002

[Quality control methods for recombinant human endostatin].

AIM: To establish the quality control methods for recombinant human endostatin. METHODS: Biological activity was determined by endothelial cell migration assays. Peptide mapping was tested by trypsin digestion and RP-HPLC. Purity was determined by non-reduced SDS-PAGE and RP-HPLC. Other tests including molecular weight, isoelectrical point, etc. were done according to the National Requirements for Biological Products (2000). RESULTS: The method of bioassay was established and used for determining activity of endostatin. Specific activity of the three batchs of drug substance was 1.45 x 10(6), 1.57 x 10(6) and 2.73 x 10(6) u.mg-1 proteins. Peptide mappings of the three batches of drug substance were completely identified. Both purity results of the products tested by SDS-PAGE and RP-HPLC were more than 99%. CONCLUSION: The established methods can effectively control the quality of recombinant human endostatin.

Cell Movement↗
PubMed1996

Applications of statistical quality control to cardiac surgery.

BACKGROUND: Although originally developed for use in manufacturing statistical quality control techniques may be applicable to other frequently performed, standardized processes. METHODS: We employed statistical quality control charts (X- s, p, and u) to analyze perioperative morbidity and mortality and length of stay in 1,131 nonemergent, isolated, primary coronary bypass operations conducted within a 17-quarter time period. RESULTS: The incidence of the most common adverse outcomes, including death, myocardial infarction, stroke, and atrial fibrillation, appeared to follow the laws of statistical fluctuation and were in statistical control. Postoperative bleeding, leg-wound infection, and the summation of total and major complications were out of statistical control in the early quarters of the study period but showed progressive improvement, as did postoperative length of stay. CONCLUSIONS: The incidence of morbidity and mortality after primary, isolated, nonemergent coronary bypass operations may be described by standard models of statistical fluctuation. Statistical quality control may be a valuable method to analyze the variability of these adverse postoperative events over time, with the ultimate goal of reducing that variability and producing better outcomes.

Coronary Artery Bypass↗
PubMedDate not supplied

Quality control of drug assays.

Previously published work relating to quality control of drug assays has dealt mainly with interlaboratory comparisons. It is suggested that participants in external quality assessment schemes wil derive the maximum benefit from their participation if a suitable intralaboratory quality control scheme is established. Such a scheme should be capable of providing estimates of within- and between-batch imprecision over the concentration range for which the assay is used and give an indication of the development of systematic error (relative to previous performance). A scheme using serum pools at 3 concentrations, each to be analysed at least in duplicate, is recommended. Adaptations of this scheme, to be used when the number of patient samples per batch does not justify this number of control samples, are discussed in relation to various analytical situations. A ratio of 1 control sample to 10 patient samples is considered reasonable. The interpretation of results from external quality assessment schemes using performance indices, graphical assessment of 'bias' and standard deviation interval (SDI = bias divided by standard deviation) and the statistical evaluation of proportional and additive error by linear regression (least squares) analysis is discussed. In some cases it has been possible, from the results of interlaboratory studies, to show that a particular method will not generally give satisfactory results when compared either with other currently available methods, e.g. UV - spectrophotometric methods for phenobarbitone, phenytoin, carbamazepine and theophylline, or on the grounds of clinical requirements, e.g. doubling dilution broth techniques for gentamicin. Improvement in intralaboratory reproducibility would facilitate the identification of technical factors contributing to interlaboratory variation.

Animals↗