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PubMed1994

Approaches to quality control with an application to a new cancer registry in a developing country.

Quality control should be maintained in all disease registries by appropriate statistical procedures to assure complete, accurate, reliable, and timely morbidity and mortality data. Shewhart control charts are recommended for evaluating item completeness. Accuracy and reliability can be evaluated with stringent diagnostic criteria, re-abstraction of records, and statistical measures such as the kappa statistic. Discrepancies between observed and expected data in various time periods can be used to evaluate whether data entering a registry meet timeliness criteria. The reporting delay distribution can be used to examine timeliness of reported data and to adjust incidence rates for potential lack of timeliness in reporting. An application of these quality control procedures is demonstrated using two variables selected from a hospital-based study consisting of 119 breast cancer records collected from the Division of Medical Records, Dr Soetomo Hospital, Surabaya, Indonesia. The results indicate that the variable LASTNAME met the selected criteria for completeness and reliability. The variable ADDRESS met the reliability but not the completeness criterion. All reported cases met the timeliness criterion. The demonstration confirmed the need for registries to establish formal quality control procedures.

Breast Neoplasms↗
PubMedDate not supplied

Web-based X-ray quality control documentation.

The department of radiology at the Medical College of Georgia Hospital and Clinics has developed an equipment quality control web site. Our goal is to provide immediate access to virtually all medical physics survey data. The web site is designed to assist equipment engineers, department management and technologists. By improving communications and access to equipment documentation, we believe productivity is enhanced. The creation of the quality control web site was accomplished in three distinct steps. First, survey data had to be placed in a computer format. The second step was to convert these various computer files to a format supported by commercial web browsers. Third, a comprehensive home page had to be designed to provide convenient access to the multitude of surveys done in the various x-ray rooms. Because we had spent years previously fine-tuning the computerization of the medical physics quality control program, most survey documentation was already in spreadsheet or database format. A major technical decision was the method of conversion of survey spreadsheet and database files into documentation appropriate for the web. After an unsatisfactory experience with a HyperText Markup Language (HTML) converter (packaged with spreadsheet and database software), we tried creating Portable Document Format (PDF) files using Adobe Acrobat software. This process preserves the original formatting of the document and takes no longer than conventional printing; therefore, it has been very successful. Although the PDF file generated by Adobe Acrobat is a proprietary format, it can be displayed through a conventional web browser using the freely distributed Adobe Acrobat Reader program that is available for virtually all platforms. Once a user installs the software, it is automatically invoked by the web browser whenever the user follows a link to a file with a PDF extension. Although no confidential patient information is available on the web site, our legal department recommended that we secure the site in order to keep out those wishing to make mischief. Our interim solution has not been to password protect the page, which we feared would hinder access for occasional legitimate users, but also not to provide links to it from other hospital and department pages. Utility and productivity were improved and time and money were saved by making radiological equipment quality control documentation instantly available on-line.

Computer Security↗
PubMed1987

Preparation and stability of low-cost liquid quality-control serum stabilized with ethanediol.

The use of quality-control serum to monitor laboratory performance is an essential part of any health laboratory. However, laboratories in many countries are disadvantaged because of the non-availability or high cost of commercial quality-control sera. Here we describe the stability of bovine serum stabilized with ethanediol, prepared at low cost by simple techniques that are available in most laboratories.

Animals↗
PubMed1979

Outliers in clinical chemistry quality-control schemes.

Results submitted to large-scale quality-control schemes are commonly judged against the mean and standard deviation (SD) of the results from other laboratories. It is desirable to ignore outlying values in estimating this mean and standard deviation, and results more than 2.5 or 3 SD from the mean are commonly rejected. I show that an outlier can so inflate the estimated SD that its presence is not detected by this method. Alternative estimators that are less influenced by outliers are described, and their application to quality-control data is discussed.

Blood Chemical Analysis↗
PubMed1993

Accurate enzyme activity measurements. Two decades of development in the commutability of enzyme quality control materials.

Commercial serum preparations are integral components of both internal and external quality control programs for enzyme activity measurements. However, properties of these materials may differ significantly from those of clinical specimens. Differences from clinical specimens may include the following: species origin of the enzyme; isoenzyme form(s); integrity of the molecular species; matrix of the solution; processes such as lyophilization; and addition of preservatives. There are also significant differences among methods measuring the activity of a single enzyme including a diversity of compounds that may serve as substrate(s); variable cofactor or metal supplementation; and differences in the substrate concentration(s), buffer substances, pH, and temperature. The measured response to each of these variations in assay technique may differ among these types of specimens. To be acceptable, quality control materials must have properties similar to those of clinical specimens. Thus, the concept of commutability that we originated and first applied to enzyme activity measurements remains useful, and its further application to the problem of "matrix effects" is reviewed here. Multivariate display techniques are applied to the specific examples of aspartate aminotransferase, alpha-amylase, and alkaline phosphatase to judge the commutability of quality control materials for these enzymes.

Bias↗
PubMed1989

Quality control in schistosomiasis programmes.

The evaluation of a schistosomiasis control programme requires regular monitoring of the performance of technicians responsible for measuring prevalence rates and intensities of infection; simple quality control measures are the most effective form of monitoring. Quality control of microscopy has usually been carried out immediately after primary examination of fresh microscope specimens or by transport of preserved urine or stool samples to a central laboratory; the first method was impossible in Madagascar, and the second involved severe loss and breakage of specimen containers. A new method involving the transport of dried filters fixed on plastic sheets with adhesive tape was therefore used. Essential requirements of the quality control methods were simplicity, effectiveness, acceptability to field technicians, and the production of results valuable to the control programme. Acceptable limits of error (ALE) were determined by a combination of trial-and-error assessment of technicians' capabilities, and the application of a rule-of-thumb derived from quality control studies in clinical chemistry. Results were prepared in the form of simple 2 x 2 tables and easily understood charts for visual assessment of results. Technicians' work varied from excellent to poor; false negative rates (FNR) were usually higher than false positive rates (FPR) and technicians' field counts of eggs were most often lower than control counts. Control proved very useful in motivating technicians, in maintaining high work standards, and in identifying technicians needing further training.

Animals↗
PubMed2003

Endoplasmic reticulum quality control of unassembled iron transporter depends on Rer1p-mediated retrieval from the golgi.

Endoplasmic reticulum (ER) quality control is a conserved process by which misfolded or unassembled proteins are selectively retained in the endoplasmic reticulum (ER). Failure in oligomerization of multisubunit membrane proteins is one of the events that triggers ER quality control. The transmembrane domains (TMDs) of unassembled subunits are determinants of ER retention in many cases, although the mechanism of the TMD-mediated sorting of unassembled subunits remains elusive. We studied a yeast iron transporter complex on the cell surface as a new model system for ER quality control. When Fet3p, a transmembrane subunit, is not assembled with the other membrane subunit, Ftr1p, unassembled Fet3p is exclusively localized to the ER at steady state. The TMD of Fet3p contains a determinant for this process. However, pulse-chase analysis and in vitro budding assays indicate that unassembled Fet3p rapidly escapes from the ER. Furthermore, Rer1p, a retrieval receptor for ER-resident membrane proteins in the Golgi, is responsible for the TMD-dependent ER retrieval of unassembled Fet3p. These findings provide clear evidence that the ER quality control of unassembled membrane proteins can be achieved by retrieval from the Golgi and that Rer1p serves as a specific sorting receptor in this process.

Ceruloplasmin↗
PubMed2002

Quality control of sputum smear examination in Cebu Province.

SETTING: Rural Health Units (RHUs) in Cebu Province, Philippines. OBJECTIVE: To assess and improve the on-going quality control of tuberculosis activities in Cebu Province. METHODS: During the period of the study, from January 1996 to December 1997, positive slides (100% in 1996 and 20% or 100% in 1997) and 20% of negative slides selected from all of the slides examined at the RHUs were assessed on the quality of smear preparation. The readings were blindly cross-checked by the provincial assessors. RESULTS: In 1997, 1) 90% of RHUs participated in the quality control activity; 2) the proportion of good quality smears increased markedly; and 3) the false positive and false negative rates did not change during the period, but most of the false positives were observed among the scanty positives of the field reading, and no false negatives were noted among the heavily positive slides. CONCLUSION: Although the false positive and negative rates did not decrease during the period, the quality control procedure resulted in marked improvements in smear preparation, a high participation of RHUs in the quality control programme and the elimination of large discrepancies between readers on positive slides in 1997. It is considered to have significantly improved the NTP's smear microscopy service in Cebu Province.

Humans↗
PubMed1984

Preparation and stability of freeze-dried Neisseria gonorrhoeae cultures used for external quality control.

In 1976, the Center for Disease Control initiated an external quality control program for the isolation and identification of Neisseria gonorrhoeae. This program required microbial samples of sufficient stability for shipment to laboratories throughout the United States. The Centers for Disease Control undertook studies to determine the most appropriate media for the propagation of strains for freeze-drying, the cell-suspending media that would afford protection during and after freeze-drying, the most favorable growth conditions, the proper times and methods for harvesting cells, the appropriate lyophilization conditions, the critical residual moisture content, and the stability of samples. These studies resulted in the development of methods for preparing and testing freeze-dried samples suitable for shipment.

Bacteriological Techniques↗
PubMed1995

Attenuated typhoid vaccine Salmonella typhi Ty21a: fingerprinting and quality control.

Live attenuated vaccines, developed with molecular genetical techniques, require new approaches for their quality control. To develop novel quality control tests that enhanced and extended existing procedures, the attenuated vaccine strain Salmonella typhi Ty21a and its parent strain Ty2 were characterized by pulsed-field gel electrophoresis (PFGE) and direct nucleotide sequence analysis. Mutant and parent strains were distinguished using fingerprints generated by the resolution on PFGE of chromosomal DNA digested with each of the enzymes SfiI, SpeI or XbaI. These fingerprints were stable through multiple in vitro passages of the vaccine strain and were identical from one batch of vaccine to another. It was also possible to distinguish between the mutant and parent strains by direct nucleotide sequence analysis of the galE gene. This analysis identified two base changes in the gene from strain Ty21a: a single base deletion causing a frameshift that would result in a truncated gene product, accounting for the galE phenotype; and a transition that eliminated an AluI restriction site. The consequent change in the AluI fingerprint of the galE gene in strain Ty21a provided a rapid, PCR-based alternative to the use of differential media or biochemical assays for the identification of the vaccine strain.

Amino Acid Sequence↗
PubMed1998

Quality control in toxicological analysis.

The validity and effectiveness of quality control procedures are reviewed here in light of the principles of analytical toxicology, and of the professional responsibility involved in awareness of the profound influence which analytical results have in the fields of health and social security. Regardless of the methods used, laboratory work should aim essentially at achieving a very high degree of reliability. Factors contributing to the 'quality' of analytical results and methods used to check their reliability are discussed here. The technical background and organization of internal and external quality control procedures are presented, with particular reference to educational aspects, and to the ways in which computer and internet technologies may be exploited for further improvement of the effectiveness of these procedures.

Clinical Laboratory Techniques↗
PubMed1997

Rapid rescreening of cervical smears as a quality control method.

The use of a rapid rescreening method as part of an internal quality control programme is reported. During a 12-month period 33,976 smears were reviewed (90.9% of total workload). Two-hundred and nineteen reports were altered, with 23 dyskaryotic smears identified, a false-negative rate of 0.07% a false-negative dyskaryotic rate of 1.7%. Smears reported as dyskaryotic were also subjected to the rapid screening method (with 86.8% correctly identified) as well as using the method to assess smears before the usual primary screen (with 67.2% of dyskaryotic smears correctly identified). Rapid rescreening as a quality control method is effective and although it has limitations, should replace 10% proportional rescreening as the preferred daily quality control method of choice.

False Negative Reactions↗
PubMed2006

Optimization and validation of a quantitative capillary electrophoresis sodium dodecyl sulfate method for quality control and stability monitoring of monoclonal antibodies.

In previous work, a capillary electrophoresis sodium dodecyl sulfate (CE-SDS) method using precolumn labeling and laser-induced fluorescence (LIF) detection was developed at Genentech Inc. as part of the control system for the quality control release of a recombinant monoclonal antibody (rMAb) (Hunt, G.; Nashabeh, W. Anal. Chem. 1999, 71, 2390-2397.). In the current work, a generic and quantitative CE-SDS assay with LIF detection of rMAbs with improved accuracy and precision is described. The implementation of an alkylating step with iodoacetamide and optimization of the incubation temperature and time, in the presence of SDS, greatly decrease any thermally induced fragmentation of nonreduced labeled rMAb samples. In addition, a quantitative study of the effects of sample buffer pH on rMAb fragmentation is also presented. Furthermore, the performance of alternative CE-SDS polymer solutions and instrumentation for quantitative analysis of rMAbs is shown in this article. The validation of this method, under the guidelines of the International Committee on Harmonization (ICH), demonstrates that the assay quantitatively determines the consistency of rMAb manufacture as it relates to size heterogeneity and product purity.

Antibodies, Monoclonal↗
PubMed1995

Mechanical and dosimetric quality control for computer controlled radiotherapy treatment equipment.

Modern computer controlled radiotherapy treatment equipment offers the possibility of delivering complex, multiple field treatments with minimal operator intervention, thus making multiple field conformal therapy practical. Conventional quality control programs are inadequate for this new technology, so new quality control procedures are needed. A reasonably fast, sensitive, and complete daily quality control program has been developed in our clinic that includes nearly automated mechanical as well as dosimetric tests. Automated delivery of these quality control fields is performed by the control system of the MM50 racetrack microtron, directed by the CCRS sequence processor [D. L. McShan and B. A. Fraass, Proceedings of the XIth International Conference on the use of computers in Radiation Therapy, 20-24 March 1994, Manchester, U.K. (North Western Medical Physics Department, Manchester, U.K., 1994), pp. 210-211], which controls the treatment process. The mechanical tests involve multiple irradiations of a single film to check the accuracy and reproducibility of the computer controlled setup of gantry and collimator angles, table orientation, collimator jaws, and multileaf collimator shape. The dosimetric tests, which involve multiple irradiations of an array of ionization chambers in a commercial dose detector (Keithly model 90100 Tracker System) rigidly attached to the head of the treatment gantry, check the output and symmetry of the treatment unit as a function of gantry and collimator angle and other parameters. For each of the dosimetric tests, readings from the five ionization chambers are automatically read out, stored, and analyzed by the computer, along with the geometric parameters of the treatment unit for that beam.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed2001

Ability of laboratories to detect emerging antimicrobial resistance: proficiency testing and quality control results from the World Health Organization's external quality assurance system for antimicrobial susceptibility testing.

The accuracy of antimicrobial susceptibility data submitted by microbiology laboratories to national and international surveillance systems has been debated for a number of years. To assess the accuracy of data submitted to the World Health Organization by users of the WHONET software, the Centers for Disease Control and Prevention distributed six bacterial isolates representing key antimicrobial-resistance phenotypes to approximately 130 laboratories, all but one of which were outside of the United States, for antimicrobial susceptibility testing as part of the World Health Organization's External Quality Assurance System for Antimicrobial Susceptibility Testing. Each laboratory also was asked to submit 10 consecutive quality control values for several key organism-drug combinations. Most laboratories were able to detect methicillin (oxacillin) resistance in Staphylococcus aureus, high-level vancomycin resistance in Enterococcus faecium, and resistance to extended-spectrum cephalosporins in Klebsiella pneumoniae. Many laboratories, particularly those using disk diffusion tests, had difficulty in recognizing reduced susceptibility to penicillin in an isolate of Streptococcus pneumoniae. The most difficult phenotype for laboratories to detect was reduced susceptibility to vancomycin in an isolate of Staphylococcus epidermidis. The proficiency testing challenge also included a request for biochemical identification of a gram-negative bacillus, which most laboratories recognized as Enterobacter cloacae. Although only a small subset of laboratories have submitted their quality control data, it is clear that many of these laboratories generate disk diffusion results for oxacillin when testing S. aureus ATCC 25923 and S. pneumoniae ATCC 49619 that are outside of the acceptable quality control range. The narrow quality control range for vancomycin also proved to be a challenge for many of the laboratories submitting data; approximately 27% of results were out of range. Thus, it is important to establish the proficiency of laboratories submitting data to surveillance systems in which the organisms are tested locally, particularly for penicillin resistance in pneumococci and glycopeptide resistance in staphylococci.

Anti-Bacterial Agents↗
PubMed1998

Quality control of beer hopped with reduced isomerised products.

The traditional method for measuring bitterness in beer by UV absorbance (ASBC 9.6) remains a viable quality control method for normally hopped beer. However, after reduction of isoalpha acids specific absorptivity of active components change and HPLC analysis shows to be a reliable method for quality control of these materials. This work is intended to adapt mathematically the ASBC (American Society of Brewing Chemist) spectrophotometrical method and to evaluate an HPLC method to control the composition of different commercial reduced isomerised products added to unhopped wort and partially kettle hopped beer. The results we obtained showed that the HPLC method is reliable for quality control of reduced isomerised products and that the traditional spectrophotometrical method is viable for quality control of beer, also using reduced isomerised products as far as an adequate factor is used.

Beer↗
PubMed1986

Quality control in the office laboratory.

Assuring quality of testing is as important in the doctor's office laboratory as it is in the hospital and independent laboratory. However, the office laboratory's problems and needs are different from those of the larger lab, and the professional laboratorian's solutions are not always appropriate for the office laboratory. It is necessary to recognize that the education and skill levels of the office laboratory staff preclude some of the quality control methods used in professionally staffed laboratories. For some test systems, new control methods will need to be developed. The professional laboratorian can provide valuable assistance to the doctor's office laboratory in assuring quality.

Laboratories↗
PubMed2005

Folding and quality control of the VHL tumor suppressor proceed through distinct chaperone pathways.

The mechanisms by which molecular chaperones assist quality control of cytosolic proteins are poorly understood. Analysis of the chaperone requirements for degradation of misfolded variants of a cytosolic protein, the VHL tumor suppressor, reveals that distinct chaperone pathways mediate its folding and quality control. While both folding and degradation of VHL require Hsp70, the chaperonin TRiC is essential for folding but is dispensable for degradation. Conversely, the chaperone Hsp90 neither participates in VHL folding nor is required to maintain misfolded VHL solubility but is essential for its degradation. The cochaperone HOP/Sti1p also participates in VHL quality control and may direct the triage decision by bridging the Hsp70-Hsp90 interaction. Our finding that a distinct chaperone complex is uniquely required for quality control provides evidence for active and specific chaperone participation in triage decisions and suggests that a hierarchy of chaperone interactions can control the alternate fates of a cytosolic protein.

Cells, Cultured↗