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At least 19 recordsLinked to original sources
PubMed1999

Antimicrobial activity and spectrum of SCH27899 (Ziracin) tested against gram-positive species including recommendations for routine susceptibility testing methods and quality control. Quality Control Study Group.

SCH27899 is an oligosaccharide, everninomicin antibiotic with activity primarily against Gram-positive pathogens. The activity of SCH27899 was evaluated against 360 routine clinical isolates by the broth microdilution (BMD), agar dilution (AD), disk diffusion (DD), and Etest (AB BIODISK, Solna, Sweden) methods. In addition, results from a nine center SCH27899 quality control (QC) trial were used to establish QC ranges. SCH27899 MICs for 330 Gram-Positive strains, including multiply-resistant staphylococci and enterococci, ranged from 0.015 to 1 microgram/ml with MIC90s of 0.12 to 0.5 microgram/ ml. SCH27899 had no measurable activity against the 30 selected Gram-negative strains tested (MICs, > 256 micrograms/ml), with the exception of Moraxella catarrhalis MICs, 0.12 microgram/ ml). Etest MICs for SCH27899 correlated well with AD and BMD results with > 90% of MICs within +/- one log2 dilutions of the reference test results. Three disk concentrations (2.5-, 5-, 10-microgram) of SCH27899 were evaluated, but minimal difference of zone diameters between disk drug contents was observed (+/- 2 mm). SCH27899 disk zone diameters correlated poorly with reference MICs due to small zone diameters (range, 11 to 22 mm) attributed to poor diffusion through agar mediums, a product of this compound's high molecular weight and solubility. The use of the DD method for SCH27899 was not recommended. The proposed MIC quality assurance limits for SCH27899 using Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 was 0.06 to 0.25 microgram/ml for both QC strains and methods. SCH27899 appears to be a eveminomicin-derivative widely active against important Gram-positive cocci, and in vitro dilution testing methods would be preferred for clinical use, validated by the recommended MIC control ranges cited in this report.

Aminoglycosides↗
PubMed2000

Angulation errors in parallel-hole and fanbeam collimators: computer controlled quality control and acceptance testing procedure.

UNLABELLED: Angulation errors in collimators of 1 degrees or even less can seriously diminish the resolution of SPECT images. We have developed a computer-controlled quality control procedure that can be used for acceptance testing and regular routine checks. METHODS: Using a marker point source and a computer-controlled x-y positioning table, we investigated 7 parallel-hole and 3 fanbeam collimators. The results are presented as collimator surface maps, which are easy to interpret visually. RESULTS: The measurement accuracy for absolute angulation errors was better than 0.32 degrees. Regional variations in channel tilt could be detected with an accuracy better than 0.16 degrees. Six parallel-hole collimators were found acceptable for high-resolution SPECT imaging. For a parallel-hole collimator that had to be replaced because of nonoptimal image quality, our measurements clearly identified regions of directionally uniform angulation errors. Two fanbeam collimators showed slight concavities. CONCLUSION: Automation of the measurement and evaluation process make this procedure suitable for both acceptance tests and routine quality control checks. It can be applied to parallel-hole, fanbeam, converging, and diverging collimators, regardless of their individual geometry. No technical collimator specifications are needed. Our results reveal subtle mechanical deformations of collimators. They also show that for a detailed investigation, angulation error surface maps should be used to discover regional preferences in channel orientation.

Equipment Design↗
PubMed1985

Who 'controls' quality control data analysis?

A common quality control tool is peer group comparison of data from commercial controls. While its real-time effectiveness is limited, inappropriate statistical management of the data can cause an individual lab's performance to be misrepresented. Here are two examples where vendor-directed data analysis contained flagrant errors. The finding that vendors use inappropriate algorithms to compare accuracy and precision of peer performance suggests a need, the author believes, to set rigorous standards of reporting for the protection of participating laboratories.

California↗
PubMedDate not supplied

Quality control, quality assurance, and proficiency testing in the andrology laboratory.

The primary goal of any andrology laboratory should be the performance of accurate, reproducible, high-quality, and clinically relevant laboratory testing. An underlining objective of such a goal is to better serve the ordering physician, and the patient, by continually improving laboratory performance. Quality control (QC) is the procedure that determines accurate and reproducible testing. Proficiency testing (PT) is the process allowing physicians to compare results from one laboratory to another. Quality assurance (QA) is the mechanism ensuring high-quality, clinically relevant testing. Together, QC, QA, and PT serve as the foundation responsible for a program that continually improves the overall quality of the testing, allowing the physician ordering the test to be more effective in treating the patient. Several examples are presented to assist the implementation of effective QC and QA programs aimed at continually improving performance in the andrology laboratory.

Andrology↗
PubMed1999

Quality control, quality assessment of laboratory tests, lipid profile.

The first external quality control survey implemented by the Japan Medical Association was performed in 1967, and now. 2.400 or more laboratories are participating in this survey. The survey for total cholesterol was performed from the first survey, triglyceride survey was started in 1973, and survey of HDL-cholesterol was started in 1981. CVs of results for above items in the surveys were greatly improved after the 1980's. CVs in the 1970's were 8 to 10 per cent. but from the middle of the 1980's they were about 3 per cent or less. The main reason for this improvement is the introduction of automated analyzers in laboratories. An additional reason for this improvement is the requirement for accuracy of cholesterol determination by physicians, because the Japan Society of Atherosclerosis decided the consensus value of cholesterol for the initiation of treatment in 1987. Supply of standard material for cholesterol since 1995 is also a reason for this improvement. In 1995. CVs of cholesterol assays by were less than 3% when using most determination kits. Two determination kits, however, were found to give very high CVs. Both of them used dry chemistry, and the reason for these discrepancies was matrix effects of the survey material.

Automation↗
PubMed1996

Quality assurance in the mycobacteriology laboratory. Quality control, quality improvement, and proficiency testing.

In conclusion, the components of QA (QC, QI, and PT) in the mycobacteriology laboratory address not only the accuracy of testing but also provide a measure for the laboratory practices that are necessary to effectively diagnose and control tuberculosis in the community. Given the extremely important role of laboratory testing in the control of tuberculosis, providing rapid diagnosis and determination of susceptibility test results, laboratories should use the recommendations concerning turnaround times as either achievable goals or a measure of whether the laboratory should be performing mycobacteriology tests. We strongly urge laboratories to include their turnaround times for test results and the timeliness of reporting those results in their annual QA program.

Bacteriology↗
PubMed1999

Quality control, quality assessment of laboratory tests, HbA1c.

HbA1c level is known to be highly correlated with blood sugar level for a while after the maximum blood sugar level was observed, and is now considered more reliable than blood sugar as a long-term index of blood sugar control in diabetic patients. The Diabetes Control and Complication Trial in United States of America reported that mean HbA1c was the dominant predictor of retinopathy progression and that 10% lower HbA1c (e.g., 8 vs. 7.2 %) is associated with a 43 % to 45 % lower risk of progression of retinopathy. This report indicated that only a 1% difference in HbA1c level has a critical effect on progression of diabetic retinopathy. It also indicates the need for high precision and accuracy of hemoglobin A1c determination for control of diabetes patients. There are various methods to measure HbA1c. but now most laboratories use the high-performance liquid chromatography (HPLC) method; immunoassay is the second most popular, followed by affinity chromatography. It has been reported that each of these methods has its own characteristics, and that their results can vary considerably. In addition, there are two types of HbA1c, one a stable component and the other a labile component, and the measured HbA1c values were influenced by the contents of labile component included in the sample. The Japan Diabetes Society took a leading role and organized a committee on inter-laboratory standardization of HbA1c Determination in 1994. The HPLC method, which eliminates labile components, is used in most laboratories. Also, the number of laboratories using the immunoassay has gradually increased, while use of the other methods has rapidly decreased. In conclusion, since the proposal of a reference method and initiation of supply of reference materials by the Japan Diabetes Society, inter-laboratory differences in measured values have become much smaller, mainly due to the methods used for measurements. We need to continue efforts toward further standardization of HbA1c determination.

Blood Chemical Analysis↗
PubMed1982

The cost of quality control.

Quality control and quality assurance increasingly are under evaluation. The number of procedures required to guarantee the medical reliability of the data generated by clinical laboratories has grown steadily with little or no signs of abating. Laboratorians would do well to anticipate the cost/benefit questions that appear inevitable. In this article, the author adduces some cost data.

Cost-Benefit Analysis↗
PubMedDate not supplied

Routine quality control tests for film-screen mammographic systems with automatic exposure control.

Quality control of the contrast and density of mammograms is of extreme importance not only because of patient dose considerations but also because of the need to monitor changes in the breast over extended periods of time. A phantom and test technique has been developed and used at two institutions for monitoring the ability of mammographic generators and phototiming systems to provide consistent contrast and density. The phantom consists of a solid acrylic block and an embedded aluminum step wedge designed specially for low kVp use. Optical densities of various portions of the phantom are used to determine constancy of density and contrast. By minimizing fluctuations due to processing and film handling, normal variations were reduced enough to determine changes in contrast and density due to generator and phototimer changes equivalent to those monitored in processor quality control programs. The data have been correlated with changes in processor function. Changes in density and contrast values have also been related to phototimer malfunction and reduced image quality.

Autoanalysis↗
PubMed2002

Quality control and quality assessment of coagulation tests in Japan.

We have used prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (Fbg), and fibronogen/fibrin degradation products (FDP) as screening coagulation tests, and antithrombin III (AT III), plasminogen (Plg), alpha2-plasmin inhibitor (alpha2-PI), protein C (PC), thrombin-AT III complex (TAT), plasmin-alpha2-PI complex (PIC), and D-dimer as special coagulation tests. We report the present condition of internal and external quality control for these coagulation tests in Japan. We made a summary report of internal quality control of some coagulation tests in Division of Hematology Laboratory, Department of Laboratory Medicine, Hokkaido University Hospital. The repeatability and reproducibility of screening tests were good, but those of special tests were partly adequate. We have participated in some external quality control surveillance including Japan Medical Association (JMA), Japanese Association of Laboratory Medical Technologists (JALMT), College of American Pathologists (CAP), and some commercial quality control surveillance. We also reported the results of some external quality control surveillance.

Blood Coagulation Tests↗
PubMed2005

Quality control and quality assessment of data from surface-enhanced laser desorption/ionization (SELDI) time-of flight (TOF) mass spectrometry (MS).

BACKGROUND: Proteomic profiling of complex biological mixtures by the ProteinChip technology of surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry (MS) is one of the most promising approaches in toxicological, biological, and clinic research. The reliable identification of protein expression patterns and associated protein biomarkers that differentiate disease from health or that distinguish different stages of a disease depends on developing methods for assessing the quality of SELDI-TOF mass spectra. The use of SELDI data for biomarker identification requires application of rigorous procedures to detect and discard low quality spectra prior to data analysis. RESULTS: The systematic variability from plates, chips, and spot positions in SELDI experiments was evaluated using biological and technical replicates. Systematic biases on plates, chips, and spots were not found. The reproducibility of SELDI experiments was demonstrated by examining the resulting low coefficient of variances of five peaks presented in all 144 spectra from quality control samples that were loaded randomly on different spots in the chips of six bioprocessor plates. We developed a method to detect and discard low quality spectra prior to proteomic profiling data analysis, which uses a correlation matrix to measure the similarities among SELDI mass spectra obtained from similar biological samples. Application of the correlation matrix to our SELDI data for liver cancer and liver toxicity study and myeloma-associated lytic bone disease study confirmed this approach as an efficient and reliable method for detecting low quality spectra. CONCLUSION: This report provides evidence that systematic variability between plates, chips, and spots on which the samples were assayed using SELDI based proteomic procedures did not exist. The reproducibility of experiments in our studies was demonstrated to be acceptable and the profiling data for subsequent data analysis are reliable. Correlation matrix was developed as a quality control tool to detect and discard low quality spectra prior to data analysis. It proved to be a reliable method to measure the similarities among SELDI mass spectra and can be used for quality control to decrease noise in proteomic profiling data prior to data analysis.

Female↗
PubMed1995

[The value of long-term results for quality control].

Quality control is as important today as always. In orthopaedic surgery this largely means follow-up of patients. Long-term thinking and planning need long-term outcome studies, since orthopaedic therapy, especially an operation, has lifelong consequences. It is essential to know whether these are better or worse than the natural course of the disease. An operation is not always the best solution. Long-term and short-term continuous control are equally important; both have to be done despite of great practical difficulties. The assessment must become more patient-related than technique-related. Prospective studies cannot provide quick long-term answers; retrospective studies are needed, too. Political aspects complicate the issue. They are also addressed in this paper.

Humans↗
PubMed2005

Mechanism of class 1 (glycosylhydrolase family 47) {alpha}-mannosidases involved in N-glycan processing and endoplasmic reticulum quality control.

Quality control in the endoplasmic reticulum (ER) determines the fate of newly synthesized glycoproteins toward either correct folding or disposal by ER-associated degradation. Initiation of the disposal process involves selective trimming of N-glycans attached to misfolded glycoproteins by ER alpha-mannosidase I and subsequent recognition by the ER degradation-enhancing alpha-mannosidase-like protein family of lectins, both members of glycosylhydrolase family 47. The unusual inverting hydrolytic mechanism catalyzed by members of this family is investigated here by a combination of kinetic and binding analyses of wild type and mutant forms of human ER alpha-mannosidase I as well as by structural analysis of a co-complex with an uncleaved thiodisaccharide substrate analog. These data reveal the roles of potential catalytic acid and base residues and the identification of a novel (3)S(1) sugar conformation for the bound substrate analog. The co-crystal structure described here, in combination with the (1)C(4) conformation of a previously identified co-complex with the glycone mimic, 1-deoxymannojirimycin, indicates that glycoside bond cleavage proceeds through a least motion conformational twist of a properly predisposed substrate in the -1 subsite. A novel (3)H(4) conformation is proposed as the exploded transition state.

Amino Acid Substitution↗