SEARCH · Search PubMed

Results for “quality control”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources

PubMed1999

Free and N-linked oligomannosides as markers of the quality control of newly synthesized glycoproteins.

It appears increasingly evident that the oligomannoside type N-glycans play important roles in the fate of newly synthesized glycoproteins in the rough endoplasmic reticulum. The variety of protein-bound oligomannoside isomers are involved in the quality control of glycoprotein, in their transport into the Golgi and probably as a degradation signal. A prerequisite of the degradation in the cytosol by the proteasome pathway is the release of the glycans as free oligomannosides. These oligomannosides are further processed in the cytosol into a peculiar isomer of Man5GlcNAc1 which enters into the lysosome to be further degraded into monosaccharides. In this review, we will illustrate how the different species of N-linked and free oligomannosides either are involved or are markers of the quality control and fate of newly synthesized glycoproteins.

Biomarkers↗

PubMed2000

[Laboratory network for the microscopic diagnosis of tuberculosis in Madagascar: quality control of slides].

As part of the National Tuberculosis Program (NTP), a quality control of the slides (search of acido-fast bacilli in the sputa) of the Treatment and Diagnosis Centers (TDC) forming the National Laboratory Network is carried out each year. In 1999, 76 TDC out of the 174 (44%) had been controlled using the method of double reading of the smears. The global concordance of the results in the 76 TDC is satisfactory (98%). Reability was 91% for the positive smears and 92% for the negative smears. A good quality of smears was observed in 53% of the centers. The TDC reliable at 100% for both positive and negative smears were 51 (67%) of which 36 (47%) had also a good quality of smears. Those later were mainly found in Toamasina, Fianarantsoa, Antananarivo and Mahajanga.

Bacteriological Techniques↗

PubMed1990

Determination of histamine in human plasma: the European external quality control study 1988.

There is an increasing interest in measuring human plasma histamine levels in various clinical conditions. A variety of 'old' and newly developed techniques are applied to meet this demand. However, the discrepancy between reported reference values for histamine in human plasma measured using this variety of techniques, suggests the existence of a certain degree of inaccuracy and imprecision. We therefore organized an external quality control study on the reliability of current histamine determinations in European laboratories. Three lyophilized plasma quality control samples, in duplicate, covering the normal and pathological range of histamine concentrations (0-45 nmol/l), two different aqueous histamine standard samples and one solvent sample were sent to 10 laboratories for the analysis of their histamine content. The following methods were used: gas chromatography-mass spectrometry (n = 2), enzymatic single isotopic assay (n = 1), fluorometric-fluoroenzymatic assay (n = 3), radioimmunoassay (n = 3) and high performance liquid chromatography (n = 2). The study was performed and evaluated according to the approved recommendations (1983) of the International Federation of Clinical Chemistry (IFCC). The target values +/- s.d. of the three plasma samples were: 39.5 +/- 4.6 nmol/l (CV = 11.6%), 2.3 +/- 2.2 nmol/l (CV = 96%) and 8.9 +/- 1.5 nmol/l (CV = 17%), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2007

Clematis huchouensis Tamura: a traditional Chinese herbal medicine and its quality control using a high performance liquid chromatography technique.

A simple, specific and reliable high performance liquid chromatography (HPLC) method has been developed and validated for study of fingerprint chromatograms of extracts from the whole plant of Clematis huchouensis Tamura (CHT) for quality control of a traditional Chinese medicinal (TCM) herb. An Agilent C18 column was used to separate extracts in this protocol and detection was made by ultraviolet absorbance at 340 nm. The column temperature was maintained at 25 degrees C. A mobile phase consisting of (a) water (with 30 mM KH2PO4) and (b) CH3CN, (c) CH3OH was found to be suitable for this separation at a flow rate of 0.8 microl min(-1) with gradient elution. Under the described conditions, a fingerprint profile of 8 compounds was collected within 35 min, which made the HPLC method unique and interesting. The fingerprint chromatograms had good stability, precision and reproducibility. Moreover, eco-climatic (habitat) effects were studied by comparison of fingerprint chromatograms obtained from extracts of CHT collected from two habitats, with rutin as a reference marker peak. The protocol developed is quite suitable for differentiation of extracts of CHT and can be used as a quality control method for this herb and a model for other herbal drugs.

China↗

PubMed1989

Reproducibility in quality control of protein (Western) immunoblot assay for antibodies to human immunodeficiency virus.

The protein (Western) immunoblot assay (IB) for antibodies to human immunodeficiency virus, like other laboratory procedures, sometimes gives variable results. In the Transfusion Safety Study, indistinguishable aliquots of four quality control (QC) samples have been routinely submitted for IB with each group of patient specimens. A false negative IB result was obtained for 1.7% of 179 assays of two known positive (QC) standards and a false positive result for 2.0% of 101 assays of two known negative (QC) standards. In addition, a test panel of 24 samples was sent on a single occasion to three widely used laboratories. A false positive result was reported by one laboratory and a false negative by a second. Although generally reliable, IB results may occasionally be in error. There is much more technical variability in the relative frequencies of antigen-antibody bands than has been recognized. These interlaboratory and intralaboratory comparisons show quality control checks are essential for all laboratories, and more than one specimen should be tested if its applicability to a specific patient is questionable. Specific bands are sufficiently inconstant for the same specimen to make appearance or disappearance on successive specimens prognostically unreliable.

Blotting, Western↗

PubMed2005

An Italian program of external quality control for quantitative assays based on real-time PCR with Taq-Man probes.

Quantitative real-time PCR techniques are increasingly being used for the measurement of nucleic acids in research applications as well as in the clinical laboratory. It is therefore important that external quality control programs (EQA) are implemented for the evaluation of the analytical aspects common to molecular tests based on quantitative PCR. The aim of this study was the development of an Italian program of external quality control for quantitative assays based on real-time PCR with Taq-Mantrade mark probes to compare the analytical performance of 42 laboratories. Participants were provided with a set of reagents (cDNA for reference curve preparation, primers-probe mix and three unknown samples) and requested to perform a conventional assay using the master mix employed in their laboratories. The quantitative results in unknown samples were analyzed. The results of our study showed clear heterogeneity in performance. Two of the 42 laboratories provided results indicating contamination during the experiment, whereas six did not provide values for at least one of the six standard points. Only 12 laboratories gave results that were both precise and accurate for all the samples tested. Regarding imprecision, 17 laboratories appeared to deviate in at least one result, whereas inaccuracy showed an inverse dose-dependent trend. Finally, 12 laboratories were not able to measure the sample with the lowest concentration. Ten of these laboratories were equipped with the same instruments. The results of this first round of analytical EQA of real-time PCR-based methods seem to indicate high variability among laboratories carrying out the same experimental protocol. These findings could have implications for any assay based on this type of technique. This survey demonstrates the importance of experimental EQAs of methodological proficiency testing. Our approach has proved useful for comparing the analytical aspects shared by all diagnostic laboratories applying quantitative assays for the measurement of nucleic acids based on the use of Taq-Mantrade mark probes and real-time platforms.

Base Sequence↗

PubMed2004

Establishing of quality control in health care system.

Importance of establishing quality control in health care system was given in this paper. It is necessary to standardize the protocols in any kind of medical treatment. Only main protocols and guidelines allow us to compare its usefulness in everyday practice doctors, medical teams and medical institutions. First, it is necessary to calculate life expectancy tables for population to whom health care system is established. Than, collecting of the data should be systematically performed by health care providers. So, if we use guidelines and standardized protocols in everyday practice we could compare medical work and with other countries which are in our interest.

Quality Assurance, Health Care↗

PubMed1973

The Leeds regional quality control scheme for clinical biochemistry: a progress report.

The results from a regional quality control scheme for clinical biochemistry are analysed. Comparison with results from an earlier period shows that the quality of several of the 15 routine analyses has improved. The methods by which the sera are produced and distributed, and the weekly results are analysed, are described. Each of the 25 laboratories receives an individual weekly computer printout within 24 hours of the deadline for the receipt of results. At the end of each six-month period a printout is produced ranking each laboratory for ;accuracy' and ;precision' for each test.

Alkaline Phosphatase↗

PubMed1989

[Quality control in computed tomography].

In comparison to the constancy checks in conventional roentgenography, quality control in computed tomography (CT) should be limited to a few simple but essential checks for image quality and radiation burden. These requirements, however, can only be fulfilled in part, because of the complexity of CT systems. Possible parameters are: water and air values, pixel noise/contrast resolution, spatial resolution, artifacts, homogeneity, contrast scale/tube voltage, slice thickness, positioning accuracy, image quality of the topogram, radiation dose and film imaging. With a simple test program, comprising 4 CT-scans and a camera test image that is presently being tested, most of the mentioned quantities can be checked.

Quality Control↗

PubMed1993

[A quality control for the culture system using endotoxin assays in human in vitro fertilization and embryo transfer].

The purpose of this study is to investigate the effects of endotoxin on human in vitro fertilization and embryo transfers (IVF-ET) and to evaluate a quality control system for a culture medium using endotoxin assays. Before the final water purification (in an ultra-pure water system with a depyrogen filter) of the medium, the sources of water were pre-purified as follows; (I) distillation-->deionization x 2, (II) distillation-->ultra-pure water system or (III) reverse osmosis system. The limulus amebocyte lysate gelation tests (sensitivities of 0.03 and 0.25EU/ml) were used to detect endotoxin in the medium and in pre-purified water (pre-water). No pregnancies occurred in the endotoxin-positive medium (endotoxin > or = 0.03EU/ml). The endotoxin-negative medium resulted in a 33.3% pregnancy rate and 13.4% implantation rate. No statistical differences in the implantation rate were found among these methods of pre-purification (I: 12.5%, II: 13.4% and III: 20.0%). Endotoxin was detected in all the pre-water between 0.25 and 4.0EU/ml. The clinical pregnancy rate (36.6%) and the implantation rate (16.9%) in pre-water of endotoxin < 0.25EU/ml were significantly higher than those (10.5% and 5.5%) in pre-water of endotoxin > or = 0.25EU/ml (p < 0.05). We confirmed that a very low concentration of endotoxin disturbed a human embryo implantation. Endotoxin assays, not only in the media, but also in pre-water before final purification are useful as a quality control for the IVF-ET program.

Culture Media↗

PubMed2006

Normal lymphocytes from leukemic samples as an internal quality control for fluorescence intensity in immunophenotyping of acute leukemias.

BACKGROUND: Multiparametric flow cytometry has become an indispensable but complex tool for the diagnosis of acute leukemias. Interpretation of immunophenotypic data within a six-parameter analytical space relies on the standardization and validation of the instrument, the reagents, and the procedure. To address whether or not residual normal lymphocytes, usually present within leukemic samples, can serve as internal quality control for fluorescence intensity, 116 leukemic and 35 normal samples were analyzed. METHODS: Eight laboratories participated in the study and recruited a total of 151 individuals including 29 patients with B-cell precursor acute lymphoblastic leukemia (BCP-ALL), 77 with acute myeloid leukemia (AML), 10 with T-cell precursor acute lymphoblastic leukemia (T-ALL), and 35 normal bone marrow donors. Lymphocytes were gated according to the CD45hi/SSClo gating strategy, after which median fluorescence intensities (MFI) as well as percentages of positive cells (%positive) for CD19, CD22, CD7, and CD3 were recorded. Nonparametric statistics were used to compare variation within and between laboratories. RESULTS: Normal lymphocytes within leukemic samples do not show substantial differences compared to lymphocytes from normal controls with respect to expression of CD19, CD22, CD7, and CD3. In particular, longitudinal control charts of MFI values for CD3 antigen provide useful information on analytical and instrument performance. CONCLUSION: Residual normal lymphocytes can serve as internal quality control for studies addressing fluorescence intensity in the setting of immunophenotyping of acute leukemias.

Acute Disease↗

PubMed2004

Alternative quality control for technetium-99m IDA complexes.

A quality control procedure for 99mTc-IDA complexes based on the use of C18 Sep-pak cartridges is developed and the validation of the procedure presented. C18 Sep-pak cartridges are pretreated by washing with 95% ethanol followed by 10(-3) N hydrochloric acid. A small amount of the 99mTc-IDA complex is applied, washed with 10(-3) N hydrochloric acid and eluted with 95% ethanol. The radiochemical purity values obtained for 99mTc-mebrofenin and 99mTc-disofenin using this Sep-pak procedure are comparable to those obtained using the standard two strip (ITLC-SG/100% methanol, ITLC-SA/20% saline) procedure.

Chromatography, Thin Layer↗

PubMed1991

Quality control does improve the performance of laboratory practice in primary health care.

Quality control surveys combined with teaching courses and expert consultations were offered to laboratories serving general practitioners in the county of Sør-Trøndelag, Norway. Fifty-one laboratories participated in the programme and the surveys during 1988-89. During the study period the number of laboratories having acceptable accuracy of their haemoglobin determination increased from approximately 80% to more than 90%. A similar increase was found also in precision where CV declined from 6.7% to approximately 2%. Additional positive effects were more close co-operation and more fruitful dialogues between the specialist laboratory and that of the general practitioners. The results offer promising perspectives to the control of laboratory performance in primary health care and the optimal use of laboratory tests.

Blood Specimen Collection↗

PubMed1997

The AutoPap 300 QC System multicenter clinical trials for use in quality control rescreening of cervical smears: I. A prospective intended use study.

BACKGROUND: The AutoPap 300 QC System is an automated device for the analysis of conventionally prepared cervical cytology slides. The AutoPap System selects an enriched population of cases for human quality control (QC) review. The device assigns a score based on the likelihood that a slide is abnormal. Cases are selected for QC rescreening that have scores exceeding a preset threshold corresponding to approximately the top 10% (or greater) of scores. METHODS: AutoPap false-negative detection, compared with a 10% random QC process, was tested in a 6-center clinical evaluation study. At each site, a block of up to 150 consecutive negative slides (including detected false-negative cases) were selected randomly daily. All slides were run on the AutoPap System and rescreened by cytotechnologists for truth determination. The false-negative cases included in the top 10% group selected by AutoPap System then were compared with false-negative detection by the random selection process. RESULTS: Fourteen thousand nine hundred fourteen cases were analyzed. The AutoPap-enriched 10% quality control group contained false-negative cases at rates 3 to 5 times that of the random selection method (P < 0.01). The sensitivity for all false-negative cases was 35% and was 52% for false-negative cases at the level of low grade squamous intraepithelial lesion and higher. CONCLUSIONS: The AutoPap 300 QC System provides the potential for a marked increase in the number of false-negative cervical cytology cases that can be detected on QC rescreening. A significant reduction in laboratory false-negative rates can be expected if this device is utilized in routine practice.

Automation↗

PubMed1991

Quality control testing of surfaces for mammalian cell culture using cells propagated in a protein-free medium.

Mouse NCTC clone 929 L (L-929) cells were propagated continuously for 3 years as monolayers in a protein-free chemically-defined medium. These cells, designated L-929-WS, were used for quality control testing of the surfaces of commercially available cell culture plastic flasks. Differences in attachment and saturation density of L-929-WS cells in a protein-free culture medium were taken to define various levels of quality of the culture vessels tested. The rate of attachment and growth of L-929-WS cells on a surface of a given quality correlated directly with that of human embryonal fibroblasts and embryonal epithelial cells grown in a serum-free medium supplemented with growth factors and hormones. L-929-WS cells propagated continuously in a protein-free medium provide a simple and sensitive assay system for more general quality control testing of surfaces used for the culture of monolayer cells.

Animals↗

PubMed2000

[Quality control in ambulatory health care. Results of an area-wide study by the public medical service of the Baden-Württemberg health insurance].

Discussions surrounding the quality of nursing care, fueled by recurring press reports, prompted the State Nursing Insurance Associations in Baden-Wuerttemberg to request the Health Insurance Medical Service to perform a quality control of outpatient nursing care services in the state. Based on a coordinated concept and for the first time in the Federal Republic of Germany, all authorized ambulatory institutions area-wide were subjected to a uniform assessment (total survey) during an official inquiry time period. The end results of these controls failed to verify the judgement often propagated by the press based on individual cases that high-quality nursing care can no longer be afforded under the present circumstances. On the average, 55% of the personnel provided to patients by outpatient nursing services were health care professionals. What is more, this professional staff rendered 75% of all nursing care services. The evaluation of the accompanied medical visits indicated that the vast majority attempted to take active nursing care into account. With regard to quality assurance, a great optimisation potential was indicated primarily in the area of nursing documentation. Only in about 35% of the nursing documents inspected was the nursing procedure always clearly evident. A future problem could arise from the fact that of all nursing professionals with leadership responsibilities, at the time of the survey only about 37% had completed the requisite professional training qualification programme of 460 training hours. If the time before the interim deadline (March 31, 2002) is not utilised, the institutions in question could face consequences that could threaten their very existence. It is evident that a large number of outpatient nursing care services in the state of Baden-Wuerttemberg do not have their economic foundation in the domain of the Nursing Care Insurance Law, which affects both patient structure and care intensity. As a consequence, there is no quality control or inspection whatsoever for the majority of nursing care services rendered by ambulatory nursing care services at present because they are not under the jurisdiction of the German Federal Social Legislation SGB XI.

Ambulatory Care↗

PubMed1992

[Quality control of stereotaxic cytologic test of non-palpable lesions of the breast].

The authors compare the accuracy and other indicators of efficiency of ten centers (1,784 total cases) performing stereotaxic cytology and adhering to a multicentric study aimed at validating a quality control system for this diagnostic procedure. The results from single centers were compared with average results. No significant differences were observed for most centers from the average sensitivity (86%), specificity (91%), positive predictive value of a dubious (57%) or positive (96%) cytologic report, inadequacy rate on malignant (6%) or benign (11%) lesions, and benign/malignant biopsy ratio (0.63). Some significant differences from the average values indicated the need for some centers to review different phases of the diagnostic process, namely to verify the accuracy of sampling sites (low sensitivity with good specificity and predictivity), to review the criteria for cytologic diagnosis (specificity less than 90%, low predictive value or higher predictive value for dubious compared with positive reports), to optimize the impact of cytology on the final decision (lack of reduction of benign/malignant biopsy ratio). Periodic check of the above parameters is proposed as a routine quality control of this diagnostic procedure.

Breast Diseases↗

PubMed2006

Preliminary investigations on the standardization and quality control for the determination of acid phosphatase activity in seminal plasma.

BACKGROUND: The determination of ACP in seminal plasma was considered as an appropriate biochemical marker to evaluate prostate function, as recommended by the WHO manual. However, few reports on the standardization and quality control for the determination of biochemical markers in seminal plasma have been documented. METHODS: Two frozen samples of seminal plasma with or without phenylmethylsulfonyl fluoride were determined for their acid phosphatase (ACP) levels. The ACP level and sperm concentration of each of 72 samples of seminal plasma obtained at 1000xg for 10 min or 3000xg for 15 min centrifugation were assayed. ACP activity in 10 samples of seminal plasma was measured immediately or standing for 30 min after dilution. The ACP levels in seminal plasma with or without chymotrypsin were also assayed. RESULTS: There was no significant difference of ACP levels (P=0.166) but of sperm concentrations (P=0.000) in seminal plasma obtained by centrifugation at different velocity. ACP activities in seminal plasma measured when standing for 30 min after dilution were significantly lower than those measured immediately after dilution (P=0.001). Both chymotrypsin and freezing-thawing had no apparent effect on the determination of ACP in seminal plasma. CONCLUSION: The results indicated that standing time after dilution and centrifugation velocity should be standardized, and frozen seminal plasma could serve as the quality control products for the determination of ACP activity among different laboratories.

Acid Phosphatase↗