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At least 1,531 records · Page 85Linked to original sources
PubMed2001

Degradation of endoplasmic reticulum (ER) quality control substrates requires transport between the ER and Golgi.

Endoplasmic reticulum (ER) quality control (ERQC) components retain and degrade misfolded proteins, and our results have found that the degradation of the soluble ERQC substrates CPY* and PrA* but not membrane spanning ERQC substrates requires transport between the ER and Golgi. Stabilization of these misfolded soluble proteins was seen in cells lacking Erv29p, a probable Golgi localized protein that cycles through the ER by means of a di-lysine ER retrieval motif (KKKIY). Cells lacking Erv29p also displayed severely retarded ER exit kinetics for a subset of correctly folded proteins. We suggest that Erv29p is likely involved in cargo loading of a subset of proteins, including soluble misfolded proteins, into vesicles for ER exit. The stabilization of soluble ERQC substrates in both erv29Delta cells and sec mutants blocked in either ER exit (sec12) or vesicle delivery to the Golgi (sec18) suggests that ER-Golgi transport is required for ERQC and reveals a new aspect of the degradative mechanism.

Amino Acid Sequence↗
PubMed2005

[A dynamic heart phantom for quality control in functional nuclear cardiac imaging].

A dynamic heart phantom for the quality control of tomographic systems used in nuclear cardiology imaging was developed, built, and tested. The heart phantom anatomically simulates the left ventricle of the heart. The variable parameters are represented by the volume of the left ventricle, the temporal course of the filling event, and the frequency of the filling of the left ventricle. These parameters can reliably simulate the wall motion, wall thickening, ejection fraction, and stroke volume of the left ventricle.

Diastole↗
PubMed1980

Quality control.

Explore the source record for details and available documents.

Education, Medical, Continuing↗
PubMed2002

Synthetic peptides identified from phage-displayed combinatorial libraries as immunodiagnostic assay surrogate quality-control targets.

BACKGROUND: Quantitative immunohistochemical (IHC) assays currently lack optimal reference quality-control material for cellular protein targets. To address this problem, we identified peptides that mimic the site on the native analyte to which the primary (monoclonal) antibody binds and used them as surrogate peptide controls. METHODS: We identified peptide candidates from a combinatorial peptide phage-display library that mimic the epitope for the 1D5 estrogen receptor (ER) monoclonal antibody (mAb). The peptide inserts of the phage clones were sequenced. Several phage-encoded peptides were then synthesized and analyzed for affinity and specificity. RESULTS: We identified phage clones that specifically bound to the ER 1D5 mAb. The binding was specific, in that the phage clones did not bind to two other isotype-matched mAbs. Their ability to bind the ER 1D5 mAb was related to the presence of a consensus sequence. Binding analysis revealed a K(d) of 8.3 x 10(-8) mol/L. The peptide was not recognized by any of 15 other mAbs commonly used for clinical IHC testing. Moreover, the peptide was able to inhibit the binding of ER 1D5 mAb to native ER, indicating that the peptide bound to ER 1D5 mAb at or close to the antigen-binding site. CONCLUSIONS: Surrogate peptide controls behave like the native analyte in terms of affinity and specificity. This technology may be especially useful when the native analyte is in short supply.

Amino Acid Sequence↗
PubMed1987

Quality control limits for teicoplanin susceptibility tests and confirmation of disk diffusion interpretive criteria.

For monitoring the performance of teicoplanin susceptibility tests, the following quality control limits are recommended: Staphylococcus aureus ATCC 29213, MIC of 0.12 to 0.5 micrograms/ml; Enterococcus faecalis ATCC 29212, MIC of 0.06 to 0.25 micrograms/ml; and S. aureus ATCC 25923, zones 15 to 19 mm in diameter (30-micrograms disks). However, some lots of Mueller-Hinton agar provided unusually large zones of inhibition with both vancomycin and teicoplanin disks, and these lots should be excluded before routine use. Teicoplanin and vancomycin differed only in their activity against oxacillin-resistant strains of Staphylococcus haemolyticus, which had decreased susceptibility to teicoplanin but were fully susceptible to vancomycin. For tests with 30-micrograms teicoplanin disks, zones less than or equal to 10 and greater than or equal to 14 mm in diameter represent resistant and susceptible breakpoints, respectively.

Anti-Bacterial Agents↗
PubMed2006

Quality control of PET radiopharmaceuticals using HPLC with electrochemical detection.

The usefulness of high-performance liquid chromatography with electrochemical detection (HPLC/ECD) in the quality control of positron emission tomography (PET) radiopharmaceuticals was evaluated for a number of substances. Chromatographic separation was performed using a reversed phase column and acetonitrile or 20 mM sodium phosphate buffer as the mobile phase. The effluent from the column was introduced into an electrochemical detector equipped with a glassy carbon electrode versus Ag/AgCl electrode operated in the direct current mode. In 19 of 21 PET radiopharmaceuticals studied, the compounds and corresponding precursors used in the synthesis of the radiopharmaceuticals could be successfully detected by the HPLC/ECD method. For 17 compounds with electroactive functional groups, such as aliphatic amines, phenols and aromatic amines, the detection limits were ppb levels for a 20-mul injection volume; this was significantly better compared with ultraviolet (UV) detection. This method could be applied to the analysis of [11C]MP4A, useful PET radiopharmaceutical for measuring acetylcholinesterase activity in the brain with no available UV absorbance.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Proposals for quality control methods of bacterial vaccines for immunostimulation. III. Effect of BCG and C. parvum on in vivo Listeria clearance and tumor growth.

Two quality control methods for BCG and C. parvum are described. First, in vivo macrophage dependent-spleen clearance of Listeria monocytogenes in inbred B10LP mice. BCG and C. parvum were administered intravenously prior to listeria inoculation (a prophylactic model). Conditions for enhanced listeria clearance including dose, route and time interval were described for each vaccine. Next, a tumor model was developed: i.e. a fibrosarcoma, chemically induced by 20-methylcholanthrene in inbred Balb/c mice. Increase in footpad thickness was used as a criterion for tumor growth. Optimal dose, route and time interval were established both in prophylactic and therapeutic situations, including intratumoral application. Depending on the conditions chosen, both inhibition and enhancement of tumor growth were observed. General conclusions of these studies are: (a) both models yield information on the effect of bacterial vaccines for immunostimulation; (b) statements on the effectiveness of any product should be based on careful studies including all variables.

Animals↗
PubMed1990

Peptide mapping on HIV polypeptides expressed in Escherichia coli. Quality control of different batches and identification of tryptic fragments containing residues of aromatic amino acids or cysteine.

Peptide mapping was used for the quality control of different batches of the recombinant HIV proteins p24 core and p24-gp41, expressed in Escherichia coli. These proteins comprise gag and env region polypeptides of the virus and may serve as suitable components in the diagnosis of HIV infections. The proteins were digested with trypsin and the mixtures were subjected to peptide mapping to prove batch equivalence of p24-gp41 and to isolate fragments of the p24-gp41 digest that differ from those of the p24 core digest. The proteins were reduced with dithiothreitol and the cysteine residues were derivatized by addition of 4-vinylpyridine. Peptide mapping was performed by means of reversed-phase high-performance liquid chromatography. Batch equivalence was proved by comparison of the maps. Peaks present in one map but not in the other were considered to be due to sequence differences or variability in digestion.

Amino Acid Sequence↗
PubMed1990

A quality control exercise of radionuclide calibrators among Belgian hospitals.

On the initiative of the Belgian Association of Hospital Physicists, eleven Belgian hospitals participated in a quality control of radionuclide calibrators conducted in collaboration with the Central Bureau for Nuclear Measurements of the Commission of the European Communities. For practical reasons the nuclide 57Co was chosen. The results from 20 different radionuclide calibrators show a fair agreement with a similar comparison carried out in 1980 in the UK.

Belgium↗
PubMed2002

Relative bias in diet history measurements: a quality control technique for dietary intervention trials.

OBJECTIVE: Investigation of relative bias in diet history measurement during dietary intervention trials. DESIGN: Retrospective analysis of human dietary data from two randomised controlled trials examining modified fat diets in the prevention and treatment of type II diabetes mellitus. SETTING: Wollongong, Australia. SUBJECTS: Thirty-five overweight, otherwise healthy subjects in trial 1 and 56 subjects with diabetes in trial 2. INTERVENTIONS: Diet history interviews and three-day weighed food records administered at one-month intervals in trial 1 and three-month intervals in trial 2. RESULTS: In a cross-sectional bias analysis, graphs of the association between bias and mean dietary intake showed that bias decreased in higher carbohydrate consumers in trial 1 (r = -0.344, P < 0.05). No other significant associations were found. In a longitudinal analysis, bias did not change over time in either trial. There were no significant differences in bias magnitudes between the trials, with the exception of monounsaturated fat measurement where bias was significantly greater and more positive in trial 2, indicating overestimation of monounsaturated fat intake with the diet history. Subjects in control and intervention groups underestimated energy, fat, saturated fat and alcohol intakes with the diet history in both trials. Overweight and obese individuals appeared to make the greatest contribution to the overall underestimation of saturated fat intake by the diet history regardless of whether they were in the control or intervention group and whether they were healthy or had diabetes. CONCLUSION: Bias in diet history measurement appears to be macronutrient-specific, with energy, fat and saturated fat consistently underreported in the interview by subjects with and without diabetes and in both intervention and control groups in a dietary intervention trial. Relative bias analysis appears to be an informative tool in quality control for dietary intervention trials when biochemical markers are unavailable.

Adult↗
PubMedDate not supplied

Validation of cefditoren MIC quality control ranges by a multi-laboratory study (2001).

The potency of cefditoren has been well documented to include broad coverage against both Gram-positive and Gram-negative organisms including species causing community-acquired respiratory tract infections. The accuracy of in vitro test results has been questioned due to debate over inconsistencies in quality control (QC) recommendations published by the National Committee for Clinical Laboratory Standards (NCCLS). Previous studies have recommended conflicting and generally broad MIC dilution ranges for several commonly used QC organisms. This study used NCCLS recommended guidelines to re-evaluate the MIC ranges using a seven laboratory M23-A2 design. The results of this multi-laboratory investigation leads to the proposal of the following QC range recommendations for cefditoren: Streptococcus pneumoniae ATCC 49619 (0.016-0.06 microg/mL); Haemophilus influenzae ATCC 49247 (0.06-0.25 microg/mL); Escherichia coli ATCC 25922 (0.12-1 microg/mL); and Staphylococcus aureus ATCC 29213 (0.25-1 microg/mL). These proposed ranges validate those suggested previously for E. coli and the problematic H. influenzae, but a three log(2) dilution range may be sufficient for S. aureus and S. pneumoniae.

Cephalosporins↗
PubMed1983

A simple, inexpensive quality control material for ortho ELT-8 platelet counts.

Dilutions of 1: 600 and 1: 3000 of 1 mum diameter polystyrene latex suspensions are simple, inexpensive materials for quality control of Ortho ELT-8 platelet counts. The coefficient of variation (CV) for a 12-week period at the 350 X 10(9)/l level was 2.2%, comparable with that of a commercial control. The CV at the 70 X 10(9)/l level was 3.5%.

Microspheres↗
PubMed2006

Comprehensive quality control utilizing the prehybridization third-dye image leads to accurate gene expression measurements by cDNA microarrays.

BACKGROUND: Gene expression profiling using microarrays has become an important genetic tool. Spotted arrays prepared in academic labs have the advantage of low cost and high design and content flexibility, but are often limited by their susceptibility to quality control (QC) issues. Previously, we have reported a novel 3-color microarray technology that enabled array fabrication QC. In this report we further investigated its advantage in spot-level data QC. RESULTS: We found that inadequate amount of bound probes available for hybridization led to significant, gene-specific compression in ratio measurements, increased data variability, and printing pin dependent heterogeneities. The impact of such problems can be captured through the definition of quality scores, and efficiently controlled through quality-dependent filtering and normalization. We compared gene expression measurements derived using our data processing pipeline with the known input ratios of spiked in control clones, and with the measurements by quantitative real time RT-PCR. In each case, highly linear relationships (R2 > 0.94) were observed, with modest compression in the microarray measurements (correction factor < 1.17). CONCLUSION: Our microarray analytical and technical advancements enabled a better dissection of the sources of data variability and hence a more efficient QC. With that highly accurate gene expression measurements can be achieved using the cDNA microarray technology.

Animals↗
PubMed1996

Matrix effects and the performance and selection of quality-control procedures to monitor PO2 measurements.

We have assessed how variation in the matrix of control materials would affect error detection and false-rejection characteristics of quality-control (QC) procedures used to monitor PO2 in blood gas measurements. To determine the expected QC performance, we generated power curves for S(mat)/S(meas) ratios of 0.0-4.0. These curves were used to estimate the probabilities of rejecting analytical runs having medically important errors, calculated from the quality required by the CLIA '88 proficiency testing criterion and the precision and accuracy expected for a typical analytical system. When S(mat)/S(meas) ratios are low, the effects of matrix on QC performance are not serious, permitting selections of QC procedures based on simple power curves for a single component of variation. As S(mat)/S(meas) ratios increase, single-rule procedures generally show a loss in error detection, whereas multirule procedures, including the 3(1)s control rule, show an increase in false rejections. An optimized QC design is presented.

Blood Gas Analysis↗
PubMed1984

Quality control and technical outcome of ISO-DALT two-dimensional electrophoresis in a clinical laboratory setting.

In this paper, we present initial quality-control evaluations for a prototype clinical laboratory, recommendations for clinical and technical data record-keeping, and laboratory protocols designed to minimize operator-dependent analytical error in a multi-user environment. These evaluations and recommendations are based on qualitative and semiquantitative two-dimensional electrophoresis studies of the College of American Pathologists' Reference Preparation for Serum Proteins (RPSP). We include the schematic map of RPSP and manually derived estimates of analytical precision for within-run and run-to-run performance with the standard 18 X 18 cm ISO-DALT system.

Amniotic Fluid↗
PubMed2003

Design and quality control issues related to dietary assessment, randomized clinical trials and meta-analysis of field-based studies in developing countries.

The essential design and quality control aspects of dietary assessment, randomized controlled trials (RCT) in developing countries and their subsequent meta-analysis are reviewed. Dietary assessment protocols consist of three stages: measurement of food intakes using a method appropriate for the study objectives, calculation of nutrient intakes and finally an evaluation of their nutrient adequacy. The latter may involve: 1) assessment of dietary diversity (average number of different foods consumed per day) and selected indices of dietary quality such as intakes of animal source foods (g/d); 2) percentage of energy from protein, fat and animal protein; 3) selected nutrient densities; and 4) dietary phytate:zinc molar ratio, as well as the prevalence of inadequate nutrient intakes calculated using a probability approach. To establish causality between the nutrient inadequacies identified and adverse health outcomes, RCT must be undertaken. A prerequisite of RCT is double-blind randomization, a procedure designed to eliminate biases arising from baseline confounding variables, unintended interventions and ascertainment bias. Results from existing RCT can be summarized via meta-analysis to gain a better understanding of the population relationship. Meta-analysis is a statistical technique involving linear models or generalized linear models, which can be performed after locating the individual studies, and selecting and abstracting all the necessary data.

Developing Countries↗