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Recent work on transmissible spongiform encephalopathies (TSEs) suggests a role for protein quality-control mechanisms in both prion protein aggregation and pathogenesis. Cytosolic accumulation of prion protein seems to be neurotoxic and might occur when proteasome function is compromised and quality control is overwhelmed. These findings are discussed in the light of other studies linking proteasome inhibition and neurodegeneration.
One of the principal objectives of the MRFIT was to teach and motivate participants assigned to the SI group to adhere to a fat-controlled dietary regimen over the course of the trial. The magnitude of the trial (with more than 12,000 participants, half of them assigned to the SI protocol, to be followed for at least 6 years in 22 separate centers) presented new challenges for maintenance of quality control over a nutrition intervention program. Collection of data to monitor changes in dietary intake over time in SI and UC groups, as well as information to assess dietary adherence levels in SI participants also presented large-scale challenges in maintenance of quality control. The MRFIT formulated many of its initial nutrition intervention and data collection decisions based on experience of the earlier National Diet Heart Study (NDHS). In order to avoid coding 7-day dietary records by local clinic nutritionists (as in NDHS), the trial opted for collection of 24-hour dietary recalls that were coded centrally at the Nutrition Coding Center. It necessitated extra attention to training and certification of clinic nutritionist-interviewers to be certain that NCC coders had sufficiently precise information about all foods entered on dietary recall forms. Since dietary intake data were collected over a time span of approximately 10 years, procedures for updating the food composition database and coding rules were a necessity. Continuing attention to training and monitoring of performance of clinic nutritionist-interviewers also was important. The MRFIT nutrition intervention program was designed with the need for interclinic comparability of intervention techniques in mind. This required not only development of study-wide nutrition intervention materials, but also necessitated ongoing attention to staff training and monitoring procedures in order to ensure intercenter comparability of efforts. The success of the nutrition intervention modality depended upon the continuing efforts of the nutrition counselors not only to achieve dietary adherence but also to monitor levels of dietary adherence over time. The NDHS experience served as a springboard for designing the MRFIT nutrition intervention and data collection procedures. It is hoped that techniques for maintaining and monitoring quality control over the MRFIT nutrition modality as outlined in this chapter may prove useful to future planners.
OBJECTIVE: The purpose of this study was to investigate if an octadecyl (18C) minicolumn could be applied successfully for quality control of 99mTc exametazime (HMPAO). METHODS: The 18C column system using saline eluent was validated against the Whatman 17 method in calculating the percent radiochemical purity of 99mTc-HMPAO. The behavior of 99mTc-pertechnetate (99mTc04-) and hydrolyzed-reduced 99mTc (99mTc02) on the column was examined, as well as method reproducibility. RESULTS: The column method is reproducible and yields results that are highly comparable to the Whatman 17 method. Technetium-99m-pertechnetate is associated with the eluent, and some 99mTc02 is retained by the column but this level is insignificant to the final patient dose. CONCLUSION: The minicolumn system is safe, simple, rapid and reliable for the quality control analysis of routine 99mTCHMPAO preparations.
Quality control parameters for broth microdilution and disk diffusion susceptibility tests were defined and the interpretive criteria for disk diffusion tests reviewed. For interpretation of tests with 15 micrograms azithromycin disks, the following criteria are recommended: greater than or equal to 19 mm for the susceptible category (MIC less than or equal to 2.0 micrograms/ml) and less than or equal to 15 mm for the resistant category (MIC greater than or equal to 8.0 micrograms/ml). Using these criteria, there was 97% overall agreement between broth dilution and disk diffusion tests; Haemophilus influenzae isolates were susceptible to azithromycin by both methods. The quality control strain Staphylococcus aureus ATCC 25923 gave zones of 21 to 26 mm in diameter in a six-laboratory collaborative study. In azithromycin broth microdilution tests the following MIC control limits are recommended: Escherichia coli ATCC 25922, 2.0-8.0 micrograms/ml; Staphylococcus aureus ATCC 29213, 0.25-1.0 micrograms/ml; and Enterococcus faecalis ATCC 29212, 1.0-4.0 micrograms/ml.
The quality controls of blood components, realised in Transfusion Centres, are necessary to check the true conformity of products in accordance with official standards. This controls are insufficient to enhance blood components quality. The practical application of the quality management allows us to reach this aim easier. After the quality display, after it efficiency and regulatory measurement and after a quality objectives selection, we consider that the professional training and the data presentation contribute to the necessary confidence for a better quality management. Finally, standardization and automatization of production processes constitute the only ways to improve the real quality, to decrease waste products and, of course, to increase the productivity.
We developed a computer subsystem that permits users to implement multirule, multistage quality control procedures. The subsystem runs as a task in the RelationaLABCOM information system and permits the collection of data from on-line instruments, as well as through manual (keyboard) entry. The choices of control rules and their combinations are at the discretion of each laboratory section, with the system automatically administering the chosen protocols for all the technologists working with the computer. Retrospective data analysis and statistics are available for review by laboratory personnel. The subsystem provides a significant improvement in the availability of real-time quality control at the bench.
OBJECTIVE: To establish the characteristic mode of HPLC fingerprint of Fufangteng combination formula for the quality control of this medicine. METHOD: 10 batch certified products were selected to establish the characteristic mode of HPLC fingerprint of Fufangteng combination formula by chromatographic pattern matching and retention time correction. RESULT: This characteristic mode of HPLC fingerprint can clearly differentiate the eligible Fufangteng products from the unqualified products. CONCLUSION: This method can provide thorough information for the quality control of Fufangteng combination formula.
Traditional quality-control methods are effective for detecting systematic error caused by deterioration of reagents or instruments, but ineffective for detecting sporadic error, which is more likely to occur in low-volume testing environments. Decentralized testing performed by individuals without formal laboratory training has a high potential for sporadic errors. New methods for validating test results, used each time a test result is produced, should replace current quality-control procedures. Under the rules of CLIA '88, manufacturers and the US Food and Drug Administration have an opportunity to develop new approaches to test validation.
Quality control (QC) process is performed to detect and correct errors in the laboratory, of which systematic errors are repeated and affect all the laboratory process thereafter. This makes it necessary for all the laboratories to detect and correct errors effectively and efficiently. We developed an on-line quality assurance system for detection and correction of systematic error, and linked it to the Unity Plus/Pro (Bio-Rad Laboratories, Irvine, USA), a commercially available quality management system. The laboratory information system based on the client-server paradigm was developed using NCR3600 (NCR, West Columbia, USA) as the server and database for server was Oracle 7.2 (Oracle, Belmont, USA) and development tool was Powerbuilder (Powersoft Burlignton, UK). Each QC material is registered and gets its own identification number and tested the same way as patient sample. The resulting QC data is entered into the Unity Plus/Pro program by in-house data entering program or by manual input. With the implementation of in-house laboratory information system (LIS) and linking it to Unity Plus/Pro, we could apply Westgard's multi-rule for higher error detection rate, resulting in more systematic and precise quality assurance for laboratory product, as well as complementary to conventional external quality assessment.
In research settings, longitudinal measurements of bone mineral density have become an integral part of the assessment of patients with metabolic skeletal disorders. To adequately utilize longitudinal measures, confidence in the long-term precision of the measurement technique must be very high. Dual-energy x-ray absorptiometry (DXA) has become commonly utilized in this context, and to better understand its long-term precision and to develop quality assurance protocols for its use, we examined the performance of eight DXA machines over a 3 year period. Anthropomorphic spine phantoms were measured frequently on each machine during the period of observation, and precision was estimated from the consistency of these determinations. Overall precision was excellent (mean longitudinal coefficient of variation, 0.4%). Nevertheless, by using a series of objective quality control criteria, small alterations in the performance of each machine were identified (mean number of changes, 4.6 in 3 years; mean magnitude, 0.0039 g/cm2, or 0.4%). The cumulative effects of those changes were sufficient to cause a significant (albeit minor) change in the regression slopes (phantom mineral density versus time) of most machines. The same quality control rules were also used to quantitate the magnitude of change and to adjust retrospectively machine performance during the period of observation, such that alterations were minimal and regression slopes were not significantly different from zero. Although the precision of DXA is excellent, alterations in machine function must be anticipated during longitudinal use. The development of quality control protocols provides the means to detect change objectively and to adjust for alterations in performance during the course of longitudinal evaluations.
UNLABELLED: The method of quality control (QC) described on the package insert for (99m)Tc-tetrofosmin requires meticulous attention to technique for accurate radiochemical purity results. About 30 min are needed. Other proposed methods have been validated only with pertechnetate. We developed a convenient new method using silica cartridges. METHODS: A silica cartridge with 70:30 methanol:water was determined to be acceptable. The method was validated against sodium pertechnetate ((99m)TcO(4)), (99m)Tc-glucoheptonate, (99m)Tc-sulfur colloid, and low-purity (99m)Tc-tetrofosmin. The validations were made by using a small volume of concentrated (99m)TcO(4) with expired kits. Instant thin-layer chromatography (ITLC) showed 6 impurities after an hour or two. The effects of sample size and flow rate were determined. The precision of repeated tests was determined by comparison with the results of 8 replications on the same batch. The 2 methods were compared at a hospital and at 2 commercial nuclear pharmacies, for a total of 134 replications, with 21 preparations being of <90% radiochemical purity. RESULTS: Volumes between 25 and 100 micro L did not affect the silica-cartridge method but did affect the ITLC method. Flow rate is critical and must be < or =5 mL/min with the silica cartridges. The SD and variance by ITLC were 7 and 51 times larger, respectively. Using the package insert technique as the gold standard, all batches of <90% radiochemical purity were rejected and those of >90% radiochemical purity were accepted. Linear regression gave the following equation: ITLC = 1.0051 x silica cartridge (R = 0.99). One- and 2-binned chi(2) analyses gave P values > 0.999999. A 2 x 2 contingency table showed 100% sensitivity, accuracy, and specificity, with a Fisher's exact test P value of 5.7 x 10(-25). Correlation was nearly perfect. CONCLUSION: According to the published rating criteria for alternate radiochemical purity tests (American Pharmacists' Association), the silica-cartridge method has a score of 90.2, versus 65.8 for ITLC. On the basis of published criteria for alternate radiochemical purity testing methods, the new method is clearly seen to be superior. Furthermore, alternate methods were validated only with free (99m)TcO(4) and colloidal impurities. We showed that these are not the significant radiochemical impurities with (99m)Tc-tetrofosmin and that those methods are not valid. This new method is fast, convenient, accurate, safe, and economical, but careful control of flow rate is required.
The need for quality control in diagnostic histopathology and cytology is analysed together with a discussion of previously reported experience in this field. The philosophical and mathematical inferences of this type of exercise are debated also in relationship to personally observed experiences in respect of uterine cervical cytology and histology. The desirability of methods of monitoring of diagnostic quality and of obtaining quality improvement are emphasized and suggestions made regarding the techniques most suited to these objectives.
This article introduces the SPD theory in modern quality management to statistically monitor the each link of medical equipment quality control, for the aim of heightening the service level and competitiveness.
Multilaboratory studies have been carried out to establish quality control limits for broth microdilution susceptibility tests with 39 different antimicrobial agents and four different control strains. For each drug-microorganism combination, 100 MIC values were recorded (20 from each of five laboratories). An acceptable range of MICs was defined as values that included greater than 95% of those 100 MICs. In a series of consecutive tests, less than or equal to 5% of the MIC values might be expected to be one doubling dilution interval above or below the limits defined in that way: at least 95% of those MIC determinations should be within the narrow control limits. The 39 antimicrobial agents provided 111 drug-microorganism combinations for which usable quality control limits could be defined. The greater than 95% rule yielded a narrow range (including only two dilution steps) with 58 of the 111 control limits, and 53 control limits permitted a more traditional three-dilution step range of MICs.
INTRODUCTION: The aim of the study was to carry out a quality control of fetal weight estimated by ultrasonography in an obstetric ward of a district hospital. MATERIALS AND METHODS: The study comprised 105 scannings. The weight estimates were projected to the date of birth, and the difference in percentage between the actual birth weight and the projected weight was estimated. RESULTS: There was a good agreement between the projected weight and the actual birth weight (r = 0.87). The mean value was -2.5%, and the standard deviation in the difference between the projected weight estimates and the actual birth weight, was 11%, which was consistent with findings in other studies. DISCUSSION: Ongoing quality control of weight estimates and establishment of obstetric databases are recommended.
In terms of quality control, the surgeon carries responsibility for the accurate measurement and recording of clinical signs at the time of first presentation. Furthermore, the surgeon has to obtain efficiently a histopathological specimen of the primary tumour and also to formulate a plan for the most effective treatment of the primary tumour and axillary lymph nodes. As part of quality control in management of infiltrating carcinomas, axillary clearance should be intrinsic to the primary treatment whether this is mastectomy or a breast conservation technique. Failure to clear the axilla can result in under-staging so that adjuvant systemic therapy may not be given to patients who might benefit from such treatment. There is need for close cooperation between radiotherapists and surgeons in the management and follow up of patients with early breast cancer.
SETTING: Ho Chi Minh City, Vietnam. OBJECTIVE: To evaluate the impact of slide reading errors at peripheral level on case-finding and treatment decisions. DESIGN: Over a 6-month period in 1997, information on date, type of slide, results of other slides from the patient, and treatment status was collected for all slides from district TB centers detected as having reading errors during smear microscopy quality control re-readings. RESULTS: Reading errors were detected in 117 slides: 115 (98.3%) were incorrectly read as negative, and 75 (65.2%) of these errors occurred in case-finding slides. In the 75 falsely negative case-finding slides, re-reading resulted in initiation of treatment in 38 patients (50.7%). The remaining 37 (49.3%) had only one positive slide and were told to return for follow-up after 6 months; the two (5.4%) who did return were both diagnosed with active TB. Detection of errors in the 40 false-negative follow-up slides resulted in treatment changes in four patients (10%). CONCLUSIONS: Quality control plays a critical role in helping to ensure the timely diagnosis and treatment of new TB cases and appropriate management of patients currently on treatment. The usefulness of quality control could be enhanced by focusing greater efforts on case-finding slides initially read as negative.
The Clinical and Laboratory Standards Institute (CLSI; formerly National Committee for Clinical Laboratory Standards, or NCCLS) M38-A standard for the susceptibility testing of filamentous fungi does not specifically address the testing of dermatophytes. In 2003, a multicenter study investigated the reproducibility of the microdilution method developed at the Center for Medical Mycology, Cleveland, Ohio, for testing the susceptibility of dermatophytes. Data from that study supported the introduction of this method for testing dermatophytes in the future version of the CLSI M38-A standard. In order for the method to be accepted by CLSI, appropriate quality control isolates needed to be identified. To that end, an interlaboratory study, involving the original six laboratories plus two additional sites, was conducted to evaluate potential candidates for quality control isolates. These candidate strains included five Trichophyton rubrum strains known to have elevated MICs to terbinafine and five Trichophyton mentagrophytes strains. Antifungal agents tested included ciclopirox, fluconazole, griseofulvin, itraconazole, posaconazole, terbinafine, and voriconazole. Based on the data generated, two quality control isolates, one T. rubrum isolate and one T. mentagrophytes isolate, were identified and submitted to the American Type Culture Collection (ATCC) for inclusion as reference strains. Ranges encompassing 95.2 to 97.9% of all data points for all seven drugs were established.