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PubMed1991

Dual-lumen catheters: quality control tests for radiopacity.

A protocol utilizing a single-point densitometer was developed for the quality control (Q.C.) of the radiopacity of dual-lumen radiographic catheters where x-rays generated at 80 kVp are typically used. Catheter contrast, defined as the difference between catheter radiopacity and background optical density (O.D.) when an aluminum plate is imaged, forms the basic Q.C. parameter. When a given catheter is repeatedly measured, catheter contrast varies with a standard deviation of 0.013 O.D. units. The effects of minor background O.D. variations on contrast are significant, but empirically correctable. A variation in measured contrast of approx. 0.01 O.D. units is observed per 10 kVp energy variation. Aluminum plate thickness has a significant effect on the results; however, other details of the protocol geometry are less important. Variations due to catheter orientation were examined and imaging of packaged catheters was demonstrated.

Catheterization↗
PubMed2006

Bap31 enhances the endoplasmic reticulum export and quality control of human class I MHC molecules.

The assembly of class I MHC molecules and their export from the endoplasmic reticulum (ER) is governed by chaperones and accessory proteins. We present evidence that the putative cargo receptor protein Bap31 participates in the transport and the quality control of human class I molecules. Transfection of the human adenocarcinoma cell line HeLa with yellow fluorescent protein-Bap31 chimeras increased surface levels of class I in a dose-dependent manner, by as much as 3.7-fold. The increase in surface class I resulted from an increase in the rate of export of newly synthesized class I molecules to the cell surface and from an increase in the stability of the exported molecules. We propose that Bap31 performs quality control on class I molecules in two distinct phases: first, by exporting peptide-loaded class I molecules to the ER/Golgi intermediate compartment, and second, by retrieving class I molecules that have lost peptides in the acidic post-ER environment. This function of Bap31 is conditional or redundant, because we find that Bap31 deficiency does not reduce surface class I levels. Overexpression of the Bap31 homolog, Bap29, decreases surface class levels in HeLa, indicating that it does not substitute for Bap31.

Bacterial Proteins↗
PubMed1981

A comparative investigation of the gel chromatography column scanning method for quality control of 99mTc-methylenediphosphonate.

Gel chromatography column scanning (GCS) is the method of choice for quality control of 99mTc-MDP preparations. Using tis method all the labelled components are obtained rapidly in one simple test procedure. The influence of various parameters such as gel type, column size, prehistory of column, equilibration, eluent, elution volume and flow rate upon the results have been investigated. Test results for 99mTc-MDP have been compared for several different GCS systems, a few TLC systems and column chromatography with fraction collection. The GCS technique, optimized for testing 99mTc-MDP preparations, has been applied in a few experiments in which very good reproducibility is required: Labelling kinetics and stability when stored at room temperature or in a refrigerator and influence of the 99mTc/(99mTc + 99Tc) atomic ratio and of the amount of radioactivity on the 99mTc-MDP labelling yield, covering parameter ranges of clinical interest, have been studied.

Chromatography, Gel↗
PubMed1985

Distribution of patients' test values and applicability of "average of normals" method to quality-control of radioimmunoassays.

Applicability of the Hoffmann's average of normals (Mn) method was evaluated in quality control (QC) of radioimmunoassays (RIA) for thyroxine, 3,5,3'-tri-iodothyronine, thyrotropin, and insulin--assays that are performed routinely in the authors' laboratory. In the first three RIAs, the patterns of the distributions were almost constant and Mn showed significant correlations with values of QC sera and intercepts of the dose-response curve. In insulin RIA, the patterns varied appreciably and Mn showed correlations with parameters that reflect a disturbance in the distribution. Exclusion of assays with abnormal distributions, however, resulted in better correlations of Mn with other QC parameters. These results suggest that average of normals method can be a very useful adjunct to conventional QC methods for RIA. The possibility that the method may be affected by a disturbance in the distribution can be monitored by computation of parameters reflecting such disturbance.

Humans↗
PubMedDate not supplied

Development of Neisseria gonorrhoeae in vitro susceptibility test methods for cefixime including quality control guidelines.

Cefixime was tested in a multilaboratory study to establish susceptibility testing interpretive criteria and quality control (QC) guidelines for Neisseria gonorrhoeae. Interpretive criteria were established by using triplicate testing of 102 representative gonococcal strains. Only a susceptible category was proposed for cefixime (greater than or equal to 31 mm and less than or equal to 0.25 micrograms/ml) because of very rare, resistant isolates. QC ranges [N. gonorrhoeae American Type Culture Collection (ATCC) 49226] were established using multiple GC agar lots, three disk lots, and a number of test replicates consistent with the National Committee for Clinical Laboratory Standards (NCCLS) M23-T guidelines. Cefixime was stable in GC agar medium for at least 21 days when stored at 2 degrees-5 degrees C. Oral third-generation cephalosporins, such as cefixime, appear to represent potentially useful clinical alternatives to parenteral drugs of the same class for single-dose therapy of gonorrhea.

Cefixime↗
PubMed2001

Quality control of the elongation step of protein synthesis by tmRNP.

Trans-translation is a quality-control process, activated upon premature termination of protein elongation, which recycles stalled ribosomes and degrades incomplete polypeptides. These functions are facilitated by transfer-messenger RNA (tmRNA, also called 10Sa RNA or SsrA RNA), a small stable RNA molecule encoded by the SsrA gene found in bacteria, chloroplasts and mitochondria. Most tmRNAs consist of a tRNA- and an mRNA-like domain connected by up to four pseudoknots. Comparative sequence analysis provided the first insight into tmRNA secondary and three-dimensional structure. Studies of the E. coli tmRNA in vitro and in vivo demonstrated that tmRNA functions as a ribonucleoprotein (RNP) complex with elongation factor Tu (EF-Tu), protein SmpB and ribosomal protein S1. The tRNA-like and mRNA-like activities of tmRNA mark prematurely terminated proteins for degradation by attaching to their C-termini peptide tags, which are recognized by numerous proteases. Studies aimed at understanding the details of the molecular mechanisms of trans-translation are ongoing.

Peptide Elongation Factors↗
PubMed2006

Combination of TLC and HPLC-MS/MS methods. Approach to a rational quality control of Chinese star anise.

In this study, a methodological approach for an effective and reliable quality control of Chinese star anise (Illicium verum Hook. F.) is developed and validated. A combined method of TLC and HPLC-MS/MS was used for differentiation of various Illicium species, especially Chinese and Japanese star anise. Species can be distinguished by their TLC flavonoid pattern. A sensitive and selective HPLC/ESI-MS/MS method was developed for the detection and quantification of lower admixtures of I. anisatum and of further toxic Illicium species at a low concentration range using the sesquiterpene lactone anisatin as a marker. The proposed assay includes a solid-phase extraction cleanup procedure with a high recovery (>90%). Chromatographic separation of anisatin was carried out on a C18 column, followed by MS detection using ESI in negative mode. The precursor/product ion transitions m/z 327 --> 127 (quantifier) and m/z 327 --> 297 (qualifier) were monitored. Statistical evaluation of this multireaction-monitoring procedure reveals good linearity and intra- and interday precision. The limits of detection and quantification are 1.2 and 3.9 microg/kg, respectively.

Chromatography, High Pressure Liquid↗
PubMed2006

NMR-based quality control approach for the identification of false positives and false negatives in high throughput screening.

The quality of the data generated in a high throughput screening (HTS) run is fundamental for selecting bona fide inhibitors and for ensuring the capture of the full richness of inhibitors present in a chemical library. For this purpose a quality control filter based on three one dimensional (1D) proton NMR experiments is proposed. The approach called SPAM (Solubility, Purity and Aggregation of the Molecule) Filter requires the acquisition of a 1D reference spectrum, a WaterLOGSY spectrum and/or a selective longitudinal relaxation filter spectrum for the identified hits dissolved in aqueous solution and in the presence of a water soluble reference molecule. This palette of experiments permits the rapid characterization of the identity, purity, solubility and aggregation state of the active compound. This knowledge is crucial for deriving accurate IC(50) and K(1) values of the inhibitors, for identifying false negatives and for detecting promiscuous inhibitors. Only compounds that pass through the SPAM Filter can be considered as starting points for medicinal chemistry efforts directed toward lead optimization. Examples of this approach in the identification of false positives in a screening run against the enzyme thymidine phosphorylase (TP) and the rescue of a false negative in a screening run against the Ser/Thr kinase AKT1 are presented.

Algorithms↗
PubMed2005

Implementation and validation of three automated methods for measuring ultrasound maximum depth of penetration: application to ultrasound quality control.

Systematic measurements of maximum depth of penetration (DOP) of ultrasound (US) scanners are essential for quality control (QC). Conventionally, DOP measurements are performed visually and as such they could be affected by various external factors, scanner control settings, and operator related errors. Automated methods should be free of the issues associated with interoperator dependence and are an attractive alternative to the visual DOP measurements. We implement and test three automated methods for measuring DOP. The methods base their measurements on signal to noise (SNR) analysis of uniform US phantom images. Two of the methods use pairs of phantom images. The third one uses a single phantom image and an "in-air" image. The validation tests included precision, sensitivity, repeatability, and usability in routine QC application. Methods based on pairs of phantom images measure the DOP with precision +/-0.2 cm or better. Precision of the single phantom image method is +/-0.05 cm, and that method is also the most sensitive of the three. All three methods are demonstrated to be repeatable among different users. Since the images for the DOP computation are collected free-hand the sensitivity to hand-transducer motion during image acquisition was also tested. Unlike the single-phantom-image based method, the methods using image pairs were found to be very sensitive to transducer motion and therefore less convenient for clinical QC applications. In conclusion, the single-phantom-image method is best suited for routine QC in a real-life clinical practice.

Algorithms↗
PubMed1997

Quality control of glycosylphosphatidylinositol anchor attachment in mammalian cells: a biochemical study.

hGHDAF28 is a chimaeric protein consisting of human growth hormone fused to a crippled signal sequence for glycosylphosphatidylinositol (GPI)-anchor addition from decay-accelerating factor, and serves as a model for quality control of GPI-anchor addition. hGHDAF28 is retained in a pre-Golgi compartment and degraded intracellularly by a mechanism with similarity to that for other endoplasmic reticulum (ER)-retained proteins (Field, Moran, Lee, Keller and Caras (1994) J. Biol. Chem. 269, 10830-10837). We have studied the specific pathway of degradation for hGHDAF28 using a number of compounds which affect protein folding and trafficking pathways in eukaryotic cells. We found that high concentrations of dithiothreitol (DTT) accelerated loss of hGHDAF28 by degradation from cell lysates, without promoting secretion or alteration of disulphide-bond distribution, in contrast to a number of other examples of ER-retained proteins where DTT alters disulphide-bond formation. Additionally, degradation of hGHDAF28 was sensitive to pH, being promoted at pH 6.0 and inhibited at pH 8.0; however, the latter effect was transient, indicating incomplete blockade. Degradation was also partially enhanced by depletion of ER calcium with thapsigargin, but this was again a partial and transient effect. Furthermore, degradation was temperature sensitive, with a gradual decrease in rate observed at lower temperatures. However, a sharp decrease in turnover between 15 degrees C and 20 degrees C, indicative of a requirement for transport to a post-ER compartment, was not observed. Degradation of hGHDAF28 was insensitive to treatment with nocodozole or compounds preventing cytoplasmic autophagy, suggesting that ER degradation is independent of classical autophagy and microtubule-dependent processes. In addition, disruption of N-glycosylation with tunicamycin, or inhibition of processing of immature N-glycan chains with castanospermine or deoxynojirimycin, had little effect on the stability of hGHDAF28, suggesting that disruption of the BiP/calnexin quality-control system by bulk cellular secretory proteins does not influence the ER-degradation pathway of hGHDAF28. Intermolecular hGHDAF28 cysteine bonds result in the formation of aggregates which are probably important in the retention of the molecule. The insensitivity of this structure to reduction in vivo, together with the enhanced degradation rate, indicates that DTT mediates its effect on stability via a molecule involved in degradation of hGHDAF28, possibly a thiol-sensitive protease.

Animals↗
PubMed1994

Quality control of red cell filtration at the patient's bedside.

BACKGROUND: Concern has been raised about the quality of white cell (WBC) reduction in blood components when it is performed by filtration at the patient's bedside. Thus, the quality of red cell (RBC) filtration performed at the bedside through two new flatbed WBC-reduction filters was evaluated. STUDY DESIGN AND METHODS: In the laboratory, 25 and 10 RBC units suspended in additive solution were stored for 1 to 2 and 14 to 21 days, respectively, and filtered through each filter. At the end of filtration, an automated complete blood count and a manual WBC count (Nageotte chamber) were determined in two samples collected from 1) a segment clamped at 5 and 25 cm below the filter along the line connecting prefiltration and postfiltration bags and 2) the postfiltration bag. In addition, 10 of the 11 nurses of the hematology outpatient clinic administered to hematologic patients 25 RBC units stored for 1 to 2 days through each type of filter. At the end of transfusion, a segment was collected from the transfusion set and a WBC count was performed as described above. No filter priming or rinsing with saline was done. RESULTS: WBC counts obtained after laboratory filtration in the segments were similar to those obtained from the postfiltration bags and from the segments collected at the bedside in all cases, with the exception of 14- to 21-day-old RBCs filtered in the laboratory through one of the filters, which produced slightly higher WBC counts in the segments than were seen in the postfiltration bags. The difference was not significant. In no case was the count in the postfiltration bag higher than that in the segment. Nurse training was easy, and bedside filtration was associated with no untoward effects. CONCLUSION: The RBC filtration at the patient's bedside can be equal in quality to that performed in the laboratory, at least in such clinical settings as hematology and oncology departments in which blood transfusion is common practice, and if simple training is provided to the nursing staff. Under the conditions of this study, it seems that quality control of RBC bedside filtration is feasible and simple.

Blood Transfusion↗
PubMed2005

The value of pH as a quality control indicator for apheresis platelets.

BACKGROUND: Standards and regulations require measurement of pH as an apheresis platelet (PLT) component quality monitor. The usefulness of this quality control (QC) measure was investigated. STUDY DESIGN AND METHODS: QC data were retrospectively reviewed for apheresis PLTs collected over 4.5 years. Three collection devices were used, the Amicus (Baxter), the CS-3000 Plus (Baxter), and the MCS+ LN9000 (Haemonetics). Each month, four components from each instrument were sampled. PLT counts and component volume were measured immediately after collection, and pH, after 5 days of storage. RESULTS: A total of 668 products were studied. pH decreased as PLT concentration increased (r(2) = 0.129, p < 0.001) and as component volume decreased (r(2) = 0.086, p = 0.02). PLT concentration and volume, however, were poor predictors of a low pH. Apheresis instrument type affected pH. The 216 components collected with use of the CS-3000 device had a lower pH than components from the other two instruments. Only 13 components had a pH value less than the acceptable level of 6.2, 12 of which were collected with the CS-3000. CONCLUSIONS: For newer-model blood cell separators, pH measurements do not provide information that might identify a manufacturing problem. Because factors that influence pH are controlled or monitored for each component, evaluation of pH on a sample group provides an indication of the quality of specific component only, rather than an effective monitor of the quality of the manufacturing process.

Blood Banks↗
PubMed1976

A quality control program for analytical procedures using standard additions.

A technique is presented which permits the rapid, simple quality control of analyses that are calibrated by the method of standard additions. The control program is based on the recovery of known amounts of added-in standard material, rather than the direct reading of instrument response.

Chemistry Techniques, Analytical↗
PubMed1986

The computer in quality control of hemodialysis patient care.

A computerized, custom-designed medical information system (MIS) has been used for more than eight years in the care of patients with chronic renal failure treated by hemodialysis in a Cincinnati medical center. A comprehensive clinical data base that forms the core of the system readily serves the need for sophisticated quality control analysis. Application of the MIS in the day-to-day management of patients in one limited care dialysis clinic is detailed, with particular attention to its capacity to contribute to the quality of care of the individual patient. Data can be stored in the system periodically with relative ease; this enables physicians, nurses, and other personnel concerned with patient care to monitor the quality of procedures and treatments used in their patients. The system is shown to be cost-effective.

Blood Pressure↗
PubMed2001

[Role and functional spectrum of HPTLC in a hospital pharmaceutical quality control program].

As part of the development of a quality assurance program (QAP), a high performance thin layer chromatography (HPTLC) analysis unit was installed in the pharmacy department at Gustave-Roussy. The HPTLC-CAMAG consists of: 1) an HPTLC-Vario development chamber for optimization of the mobile phases; 2) TLC Sampler III automated sample applicators; 3) solid teflon migration chambers, i.e., horizontal tanks that enable separation to be carried out either in sandwich or in saturation mode; 4) a TLC Scanner 3 densitometer controlled by CATS 4 software; and 5) a Pentium MMX 233 MHz personal computer with an external backup unit. HPTLC quantitative and qualitative analysis has now reached a remarkably high level of development and performance. The samples (aqueous or non-aqueous solutions) that are to be processed are automatically applied by spraying (50-300 nl) in calibrated bands of a few mm (with up to 64 3-mm bands per 10 x 20 cm plate) on high-performance stationary phases and of wide technological diversity. The chromatogram is obtained in 10 min, and run over a migration pathway of 5-6 cm. The plates are read by absorption-reflection or fluorescence-reflection at an ad hoc wavelength (190-800 nm), then the peak areas which have been scanned are calculated by the trapezoid method. The calibration curves are generated by Michaelis-Menten non-linear regression, and validated by internal quality control. The analytical yield is high, i.e., up to 50 assays and 250 determinations per day. HPTLC analysis covers a wide functional range, and can be used in the following ways: 1) as a teaching tool for separative analysis and GLP; 2) it is an invaluable method for the optimization of mobile phases and for the determination of absorption spectra and absorption maxima, with a view to developing HPLC methods in complex matrices; 3) it provides major support for post-production quality control of prescribed hospital preparations of all types, e.g., those connected with parenteral nutrition, chemotherapy, synthetic narcotic analgesia; and it can also be used for dry dosage analysis; 4) it is useful in pharmaceutical assessment, e.g., in studies on the physico-chemical characteristics of various substances, such as their identity, purity, concentration, stability and compatibility, particularly with regard to generic products; 5) it can contribute to monitoring the safety of medical apparatus and equipment via the analysis of container-content interactions; 6) it provides a qualification system for personnel and procedures for within- and between-center validation of GMP. Setting up such an HPTLC quality control unit requires a basic investment of about 0.9 MF or 70,000 US dollars for a cost of no more than 10 F or 1.5 US dollars (including tax) per routine assay. After 18 months in operation and 16,500 assays, the HPTLC analysis unit has become one of the mainstays of the Gustave-Roussy QAP.

Chromatography, High Pressure Liquid↗
PubMed1997

An intralaboratory quality control program for quantitation of CD34+ cells by flow cytometry.

This study was undertaken to develop a quality control protocol to monitor instrument, operator, and CD34 assay performance. A dual level control system was established by cryopreserving aliquots of cells from peripheral blood progenitor cell (PBPC) collections exhibiting different percentages of CD34+ cells. Twenty-five samples from each control specimen were assayed to establish a control range (mean +/- 2 SD). Levey-Jennings graphs were prepared for each control specimen to plot multiple measurements of CD34%. No significant differences were observed between fresh or cryopreserved PBPC aliquots in terms of light scatter properties or CD34 antigen density within the gated cell population. Cryopreserved PBPC samples are ideal for serving as a positive methodology control for daily CD34 analysis. Furthermore, such a system can help identify problems with assay reagents, sample preparation technique, or incorrect data analysis.

Antigens, CD34↗
PubMed2006

Uncertainties of exposure-related quantities in mammographic x-ray unit quality control.

Breast screening programs operate in many countries with mammographic x-ray units subject to stringent quality control tests. These tests include the evaluation of quantities based on exposure measurements, such as half value layer, automatic exposure control reproducibility, average glandular dose, and radiation output rate. There are numerous error sources that contribute to the uncertainty of these exposure-related quantities, some of which are unique to the low energy x-ray spectrum produced by mammographic x-ray units. For each of these exposure-related quantities, the applicable error sources and their magnitudes vary, depending on the test equipment used to make the measurement, and whether or not relevant corrections have been applied. This study has identified and quantified a range of error sources that may be used to estimate the combined uncertainty of these exposure-related quantities, given the test equipment used and corrections applied. The uncertainty analysis uses methods described by the International Standards Organization's Guide to the Expression of Uncertainty in Measurement. Examples of how these error sources combine to give the uncertainty of the exposure-related quantities are presented. Using the best test equipment evaluated in this study, uncertainties of the four exposure-related quantities at the 95% confidence interval were found to be +/-1.6% (half value layer), +/-0.0008 (automatic exposure control reproducibility), +/-2.3% (average glandular dose), and +/-2.1% (radiation output rate). In some cases, using less precise test equipment or failing to apply corrections, resulted in uncertainties more than double in magnitude.

Breast↗
PubMed1995

[Therapeutic quality control of follow-up of oral anticoagulation in primary care: 4-year experience].

OBJECTIVE: To find the rate of therapeutic control and the frequency of complications among patients receiving oral anticoagulant therapy, attending in a primary care center. DESIGN: Descriptive study over the last four years. SETTING: An urban primary care center. PATIENTS AND METHODS: We included all patients in oral anticoagulant treatment controlled in our center among 1989 and 1993, excluding that patients with less than three months in control, or discontinued control. The prothrombin time was measured by international normalized ratio (INR). To measure the therapeutic quality control, we used the method proposed by the International Society of Thrombosis and Haemostasis. The frequency of complications was measured in number of events/100 patients/year. RESULTS: In the 136 patients studied the average time in control was 23.57 months. The 68.37 percent of determinations were within satisfactory ranges. The frequency of minor hemorrhages was 13.36 by 100 patients/year, 1.08 of major hemorrhages, and 2.53 of thromboembolism events. CONCLUSIONS: The results obtained in this audit are similar to the communicated by other centers. The therapeutic control of oral anticoagulants can carry out in primary care with enough quality and some advantages: more facility to health education, better accessibility, and more integration of anticoagulation therapy in global care of patients.

Administration, Oral↗