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At least 1,045 records · Page 58Linked to original sources
PubMed1988

Quality control of mammographic equipment: a 5-year follow-up.

A quality-control project covering 56 pieces of mammographic equipment was carried out in Finland. The evaluation was based on the determination of contrast, film optical density, resolution, focus size, tube voltage, exposure time, half-value thickness, reproducibility and linearity of exposure, surface and exit dose, and defects at each centre when employing routinely used techniques. Dose and image quality were assessed using three phantoms. The results are compared with those obtained 5 years earlier and by other authors. Although the situation has, in many ways, improved considerably over the last 5 years (for instance, the average whole-breast dose has fallen on average by 84%, 7.37----1.10 mGy), there is still room for further improvement, especially in the optimization of the developing processes.

Female↗
PubMed1981

Evaluation of quality-control materials for high-density-lipoprotein cholesterol quantitation.

Commercial quality-control materials and frozen plasma and serum pools were evaluated for high-density lipoprotein (HDL) cholesterol quantitation by the heparin-Mn2+ and phosphotungstate-Mg2+ precipitation methods and by ultracentrifugal and electrophoretic methods. We evaluated among-day precision; inter-method differences in HDL cholesterol quantitation; lipid composition and electrophoretic mobility of th lipoprotein density fractions; and the effects of modifications in reagent concentration and temperature. Frozen plasma pools (in-house) and frozen serum pools (prepared by the Center for Disease Control) were determined to be suitable HDL controls. Also, a commercial lyophilized serum free of very-low-density lipoprotein (VLDL) to which VLDL is added in a diluent solution (Analytical Control) also appeared suitable as an HDL control material. Conventional lyophilized pools (Lyphochek Elevated, Monitrol I, Ortho Normal, Precilip) were less suitable as control materials because of poor between-day precision for one or both of the precipitation methods and, in some cases, because of large absolute differences observed between the HDL methods. A serum pool stabilized with ethylene glycol (Beckman Level I) was the least as appropriate as an HDL control material. Other lyophilized pools--Lipid Fraction Control (Hyland) prepared by a modified lyophilization process and Lipidophor (Immuno Diagnostika) prepared by lyophilization with a stabilizing agent--appear promising.

Apolipoproteins↗
PubMed1991

[Quality control of a computer system for repeat prescriptions].

The results of a quality control of a computer system of repeated prescription (RPS) and its basic features are reported. The selected quality criteria were the following: reduction of the bureaucratic index in the visit, correct fulfillment of the treatment order, health attention circuits of the RPS, and compliance of the patient with the treatment. The record of activities and a random sample of treatment orders (TO) were used as sources of data. Quality indexes near the optimal standard (OS) were achieved: bureaucratic index 12.8% (OS = 15%), fulfillment of the TO 94% (OS = 100%), specified dosages 86% (OS = 100%), prescriptions in out-of-date orders 7% (OS = 0%), use higher than calculated 1% (OS = 0%), and use lower than calculated 36% (OS = 25%). Finally, the corrective measures for the detected quality problems are proposed, and the advantages of the computer RPS are discussed.

Algorithms↗
PubMed1991

The need for primary quality control of commercially available immunoassay kits.

Discrepancies among three commercially available luteinising hormone (LH) radioimmunoassay RIA kits, all calibrated against the second-IRP-HMG (World Health Organisation International Laboratory for Biological Standards), were observed. Even though the Japan Radioisotope Association carries out external quality control in Japan every year, inaccuracies still exist. This problem also exists elsewhere, and it is proposed that a global monitoring system of primary quality control (PQC) should be introduced by a body such as the World Health Organisation.

Luteinizing Hormone↗
PubMed1993

FRAR course on laboratory approaches to aging. Genetic quality control in laboratory rodents.

Laboratory rodents are widely used in gerontological research. Many different strains are available, and superficially there is little to distinguish them (many are albino), although they may differ markedly in life span and pattern of spontaneous disease, as well as for a whole range of biochemical, immunological, behavioural and physiological characteristics. As experience has shown that strains can easily become muddled, some form of genetic quality control is essential. There is no single method of genetic quality control which can be recommended for all occasions. Methods based on identification of Mendelian genetic markers, such as biochemical and immunological polymorphisms can be sensitive, but may be expensive and require considerable expertise. Methods based on simultaneous study of several markers, such as skin grafting and polyvalent strain-specific antisera, may be cheaper but less flexible. DNA fingerprinting and the use of microsatellite markers appear to be the methods of choice in the future, though these are still expensive and require considerable expertise.

Animals↗
PubMed2005

Quality control assessment of ePTFE precoating procedure for in vitro endothelial cell seeding.

Over the past two decades, in vitro autologous endothelial cell (EC) coverage of expanded polytetrafluoroethylene (ePTFE) graft has been developed and clinically applied with success in infrainguinal bypasses. Before endothelialization, the luminal surface of the graft has to be coated with a currently used fibrinolytically inhibited fibrin glue. The aim of this work is to validate the precoating of the ePTFE (4 mm ID) ringed graft with fibrin. Twenty cm-long grafts were precoated with fibrin glue (2 operators) then fixed for microscopy investigations. Grafts were sliced into 3 regions. Thickness analysis was evaluated by image processing. Three grafts have been tested for endothelialization and observed at days 3, 8. Cell-free coated ePTFE were imaged using high-frequency ultrasound modality. Whatever the examined segment an overall homogeneous covering protein is shown. Fibrin thickness after image processing is 8.5+/-0.25 and 4.1+/-0.4 microm for two operators (P < .001). We have evaluated reproducibility and inter- and intra-variability of the operator, assessed quality controls and quality assurance all along the prosthesis and finally endothelialization and subsequent behaviour under shear stress conditions.

Bioprosthesis↗
PubMed2002

Quality control of the blood pressure phenotype in the European Project on Genes in Hypertension.

OBJECTIVES: In the European Project on Genes in Hypertension (EPOGH) standardized epidemiological methods were used to determine complex phenotypes consisting of blood pressure (BP) in combination with other traits. In this report, we present the quality control of one of the BP phenotypes. METHODS: In seven European countries eight different research groups recruited random samples of nuclear families. Trained observers measured the BP five times consecutively with the participants in the seated position at each of two separate home visits, 1 to 3 weeks apart, according to the guidelines of the British Hypertension Society. Quality assurance and quality control of this BP phenotype were implemented according to detailed instructions defined in the protocol of the EPOGH study. RESULTS: On 31 August 2001, BP measurements of 2476 subjects were available for analysis. Fewer BP readings than the five planned per visit occurred in one of the eight centres, but only in 0.4% of the home visits. Across centres the relative frequency of identical consecutive readings for systolic or diastolic blood pressure varied from 0 to 6%. The occurrence of odd readings ranged from 0 to 0.1%. Of the 49,488 systolic and diastolic BP readings, 24.0% ended on a zero (expected 20%). In most EPOGH centres there was a progressive decline in the BP from the first to the second home visit. Overall, these decreases averaged 2.36 mmHg [95% confidence interval (CI): 1.98-2.74, P < 0.001] for systolic BP and 1.74 mmHg (95% CI: 1.46-2.02, P < 0.001) for diastolic BP. CONCLUSIONS: Quality assurance and control should be planned at the design stage of a project involving BP measurement and implemented from its very beginnings until the end. The procedures of quality assurance set up in the EPOGH study for the BP measurements resulted in a well-defined BP phenotype, which was consistent across centres.

Adolescent↗
PubMed2006

Quality-control ranges for antimicrobial susceptibility testing by broth dilution of the Brachyspira hyodysenteriae type strain (ATCC 27164T).

There are no approved standards for antimicrobial susceptibility testing of the fastidious spirochete Brachyspira hyodysenteriae. An interlaboratory study was performed to establish MIC quality control ranges for six antimicrobial agents for the type strain of B. hyodysenteriae using broth dilution. The results showed that B. hyodysenteriae B78T ATCC 27164T is a suitable quality control strain. This is a first step toward standardization of methods regarding this anaerobe.

Animals↗
PubMed1990

Quality control test for immunoreactivity of radiolabeled antibody.

A rapid method for the measurement of the immunoreactive fraction of a radiolabeled monoclonal antibody or antibody fragment has been developed. This may be used as a quality control test prior to patient administration of the radiolabeled antibody preparation. The test employs solid phase antigens and the assay is conducted under conditions of antigen excess. Assay parameters have been evaluated and a standardized procedure has been developed. The assay has been compared to a standard extrapolation method and found to give approximately the same result. The test has been used on four different radiolabeled antibodies currently in clinical trials in patients with colorectal cancer. Mean immunoreactive fractions for these radiolabeled antibodies ranged from 35 to 65% and the variability of the immunoreactive fraction ranged from 140 to 240% for different antibodies. We conclude that the quality, defined as the immunoreactive fraction, of radiolabeled antibodies is both low and highly variable, indicating the need for a quality control test of these radiopharmaceuticals in the clinic prior to patient administration.

Animals↗
PubMed1998

Proteasome and thiol involvement in quality control of glycosylphosphatidylinositol anchor addition.

Improperly processed secretory proteins are degraded by a hydrolytic system that is associated with the endoplasmic reticulum (ER) and appears to involve re-export of lumenal proteins into the cytoplasm for ultimate degradation by the proteasome. The chimaeric protein hGHDAF28, which contains a crippled glycosylphosphatidylinositol (GPI) C-terminal signal peptide, is degraded by a pathway highly similar to that for other ER-retained proteins and is characterized by formation of disulphide-linked aggregates, failure to reach the Golgi complex and intracellular degradation with a half life of approximately 2 h. Here we show that N-acetyl-leucinal-leucinal-norleucinal, MG-132 and lactacystin, all inhibitors of the proteasome, protect hGHDAF28; hGHDAF28 is still proteolytically cleaved in the presence of lactacystin or MG-132, by the removal of approximately 2 kDa, but the truncated fragment is not processed further. We demonstrate that the ubiquitination system accelerates ER-degradation of hGHDAF28, but is not essential to the process. Overall, these findings indicate that GPI quality control is mediated by the cytoplasmic proteasome. We also show that the presence of a cysteine residue in the GPI signal of hGHDAF28 is required for retention and degradation, as mutation of this residue to serine results in secretion of the fusion protein, implicating thiol-mediated retention as a mechanism for quality control of some GPI signals. Removal of the cysteine also prevents inclusion of hGHDAF28 in disulphide-linked aggregates, indicating that aggregate formation is an additional retention mechanism for this class of protein. Therefore our data suggest that an unpaired terminal cysteine is the retention motif of the hGHDAF28 GPI-processing signal and that additional information may be required for efficient engagement of ER quality control systems by the majority of GPI signals which lack cysteine residues.

Acetylcysteine↗
PubMed2001

Statistical issues of quality control in organised breast cancer screening.

BACKGROUND: European guidelines for breast-cancer screening recommend an integrated approach of mammography screening with subsequent assessment and biopsy, if required, in one screening unit under permanent quality control, for which target values are released. Although the calculation of the respective rates (e.g. for participation, assessment, biopsy, or cancer detection) appears trivial, the statistical assessment of their compatibility with the target values is less obvious. This is especially true if subjects with a positive diagnostic result leave the screening-assessment chain prematurely, and information about further diagnostic results outside the organised screening is lacking. METHOD: Statistical models for the basic situation, in which complete information about the screening and assessment outcome is available, as well as for when information is incomplete, are presented. The statistical methods for obtaining the confidence limits, statistical tests and sample sizes needed to obtain a desired power of tests for the process parameters of interest are also given. RESULTS: The sample-size calculations indicate that large numbers of enrolled subjects are required to obtain reasonably narrow confidence limits, and that incomplete information about the outcome of diagnostic procedures among screening positives considerably worsens the feasibility of quality control. CONCLUSIONS: Although the methodology is specified for breast-cancer screening, it should be adaptable easily to other screening issues.

Breast Neoplasms↗
PubMedDate not supplied

Pharmaceutical quality control of the investigational polymer-conjugated platinum anticancer agent AP 5280.

AP 5280 is a novel polymer-conjugated platinum anticancer agent currently in Phase I clinical trials. In order to guarantee the quality of AP 5280 drug substance for use in the manufacture of a drug product for intravenous human use, an array of tests was utilized for its quality control. Proton nuclear magnetic resonance (1H NMR) spectroscopy and infrared (IR) spectroscopy were employed for structural identification. The molecular weight (MW) and MW distribution, which play a large role in the distribution of AP 5280 in vivo, were determined by Size Exclusion Chromatography (SEC). Platinum binding assessment was performed using platinum nuclear magnetic resonance (195Pt NMR) spectroscopy. The free platinum content and release profile of small platinum species, measured using Flameless Atomic Absorption Spectroscopy (F-AAS), were determined as a measure of molecular integrity, a very important aspect of its assumed mechanism of action. The total platinum content of the copolymer was determined employing flame Atomic Absorption Spectroscopy (AAS). The combined results of the analyses performed on AP 5280 drug substance provided a meaningful picture of its structure, size, and integrity--an excellent basis for its quality control.

Acrylamides↗
PubMed2006

[Application study of human sperm motility bioassay in IVF laboratory quality control].

OBJECTIVE: To investigate the sensitivity of human sperm survival bioassay to using known concentrations of potential toxin of formalin and to elevate the application value of human sperm motility assay as a quality control method in detecting the components used in IVF program. METHODS: Fresh semen was obtained from healthy males at andrology laboratory by masturbation. Sperm was processed on a gradient column of isolate medium and PBS medium. In experiment 1, the medium with 0.25%, 0.75% concentration of formalin and control medium were added to the Falcon culture tubes containing HTF medium with or without 0.3% bovine albumin serum and with or without light mineral oil. In experiment 2, in 3 types of culture tubes containing HTF medium with or without 0.3% bovine albumin serum and with or without light mineral oil, the sperm was exposed to each culture tube and cultured for 24 and 48 hrs at room temperature, and the motile sperms were counted under the microscope. RESULTS: The average sperm motility index in the HTF medium with 0.25% formalin at 24 hrs was 0.594 +/- 0.331, significantly higher than in the HTF medium with 0.75% formalin (0.450 +/- 0.284) (P < 0.01). In the medium containing 0.25% and 0.75% formalin with 0.3% bovine albumin serum and light mineral oil, the average sperm survival indexes were 0.683 +/- 0.334 and 0.527 +/- 0.345, respectively, higher than without bovine albumin serum and light mineral oil (0.394 +/- 0.311 and 0.424 +/- 0.311). The average sperm index of 7 ml tissue culture tube made in Denmark was 0.677 +/- 0.335, higher than the other two types of culture tubes made in the USA (0.551 +/- 0.317 and 0.596 +/- 0.327) (P < 0.001). When the sperm cultured in the medium with 0.3% bovine albumin serum and light mineral oil, the average sperm survival indexes were 0.821 +/- 0.259 and 0.645 +/- 0.335, respectively, higher than without bovine albumin serum or light mineral oil (0.571 +/- 0.321 and 0.395 +/- 0.245) (P < 0.01). CONCLUSION: The sperm survival bioassay is a sensitivity quality control method to detect the components in the IVF laboratory. The 7 ml tissue culture tube made in Denmark is most suitable for culturing human embryos. Sperm can be protected when cultured in the medium with 0.3% albumin bovine serum and light mineral oil.

Adult↗
PubMedDate not supplied

Validation of standardized high-performance thin-layer chromatographic methods for quality control and stability testing of herbals.

In herbal medicinal products the entire herbal drug or an herbal drug preparation is regarded as the active pharmaceutical ingredient, regardless of whether constituents with defined therapeutic activity are known. In quality control and stability testing of herbal medicinal products, fingerprint chromatograms are used as powerful tools to evaluate and compare the composition of compounds in such products. To fulfill the International Conference on Harmonization and Good Manufacturing Practice-based regulatory requirements in pharmaceutical quality control, chromatographic fingerprint analysis needs to be validated. Based on a standardized methodology, this paper provides a comprehensive concept for evaluating validation parameters for planar chromatographic fingerprinting by considering the stationary phase, sample application, developing solvent, chromatogram development, plate labeling, derivatization, documentation, and chromatographic equipment. Validation parameters addressed include stability of the analyte, selectivity, robustness testing, and method reproducibility.

Chromatography, High Pressure Liquid↗
PubMed1998

[Systematic internal quality control in surgery 1993 to 1997].

From April 1, 1993 to Dec. 31, 1997, the perioperative course of 5690 patients was recorded prospectively and postoperative morbidity and lethality was determined in the framework of a program for a systematic internal quality control. Goal of the program is the demonstration of treatment quality which possibly out quality improvement. The share of old and sicker patients was significantly increasing during the observation period. Morbidity and hospital lethality remained constant despite a rising necessity of postoperative intensive care. High risk surgery was performed on more patients in the university hospital than in non-university hospitals. The rate of postsurgical complications was lower, length of stay was equal (surgery for inguinal hernia) or lower (cholecystectomy). The rate of not indicated appendectomy could be lowered and morbidity and lethality in the treatment of esophagus carcinoma was lowered by the application of this concept. For the partial duodenopanceatectomy, the examination of the individual surgeon as a risk factor revealed a significant dependence on the experience of the surgeon. There was only a tendency of this effect demonstrable in medium or small surgery like colon resection of gastrectomy. The rate of continence preservation in rectal carcinoma was increased to 75% combined with a drop of perioperative morbidity and length of stay. The systematic internal quality control allows for the assessment of treatment quality and the fast recognition of weak spots. It is a suitable complementary tool for quality improvement in the framework of quality management in surgical patients. The extension of the concept by recording postoperative quality of life and long time results is planned.

Abdomen↗
PubMed1989

Characterization of laboratory working standard for quality control of immunometric and radiometric estrogen receptor assays. Clinical evaluation on breast cancer biopsies. Italian Committee for Hormone Receptor Assays Standardization.

The objective of the study was to characterize a low-cost and reliable working standard material for quality control of estrogen receptor (ER) determination with dextran-coated charcoal (DCC) and enzyme immunoassay (EIA) methods. Human fibromatous uterine lyophilized cytosol demonstrated good characteristics of stability and applicability for this purpose. Eleven laboratories participated in the intralaboratory and interlaboratory quality control study, and they achieved slightly higher coefficients of variation for ER-EIA (interlaboratory, 37.7%; intralaboratory, 22.9%) than for ER-DCC (interlaboratory, 24.2%; intralaboratory, 15.7%). There was an excellent correlation between ER results with ER-EIA and ER-DCC for 268 breast cancer biopsies. Quality assurance for ER assays using DCC techniques and immunometric methods with monoclonal antibodies (ER-EIA) can be set up with this available material of human origin to satisfy the characteristics of both techniques and the species specificity of monoclonal antibodies.

Breast Neoplasms↗