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Validation Protocols (validation + protocol)
Selected AbstractsDetermination of dichloroanilines in human urine by gas chromatography/mass spectrometry: validation protocol and establishment of Reference Values in a population group living in central ItalyRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2006Roberta Turci 3,4- and 3,5-Dichloroanilines (DCAs) are common markers of some non-persistent pesticides, e.g. linuron, diuron, vinclozolin, and iprodione. The general population may be exposed to these DCAs and/or their precursors mainly through diet. Since adverse effects on human health, such as endocrine disruption, have been reported, biological monitoring is essential for exposure assessment both of occupationally exposed subjects and of the general population. A highly sensitive and selective gas chromatography/mass spectrometry (GC/MS) method has been developed for the determination of 3,4- and 3,5-DCAs in urine using 4-chloro-2-methylaniline as an internal standard. The selected ion monitoring (SIM) mode was employed for quantitation of the analytes. The sample treatment procedure is simple and fast and no derivatization is required. The overall method was validated including uncertainty measurement. The limit of detection (LOD) and the lower limit of quantitation (LLOQ) were determined to be 0.005 and 0.010,µg/L for both analytes. The method was then applied to the establishment of reference values for a population group living in a rural area of central Italy (Novafeltria, Marche). A total of 151 out of 153 samples were found to be positive for 3,5-DCA, and 81.7% were positive for 3,4-DCA. For this group, 3,4-DCA levels ranged from 0.01 to 6.19,µg/L, while 3,5-DCA urinary concentrations were between 0.02 and 6.71,µg/L. Copyright © 2006 John Wiley & Sons, Ltd. [source] Real-Time Polymerase Chain Reaction: A Novel Molecular Diagnostic Tool for Equine Infectious DiseasesJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2006N. Pusterla The focus of rapid diagnosis of infectious disease of horses in the last decade has shifted from the conventional laboratory techniques of antigen detection, microscopy, and culture to molecular diagnosis of infectious agents. Equine practitioners must be able to interpret the use, limitations, and results of molecular diagnostic techniques, as they are increasingly integrated into routine microbiology laboratory protocols. Polymerase chain reaction (PCR) is the best-known and most successfully implemented diagnostic molecular technology to date. It can detect slow-growing, difficult-to-cultivate, or uncultivatable microorganisms and can be used in situations in which clinical microbiology diagnostic procedures are inadequate, time-consuming, difficult, expensive, or hazardous to laboratory staff. Inherent technical limitations of PCR are present, but they are reduced in laboratories that use standardized protocols, conduct rigid validation protocols, and adhere to appropriate quality-control procedures. Improvements in PCR, especially probe-based real-time PCR, have broadened its diagnostic capabilities in clinical infectious diseases to complement and even surpass traditional methods in some situations. Furthermore, real-time PCR is capable of quantitation, allowing discrimination of clinically relevant infections characterized by pathogen replication and high pathogen loads from chronic latent infections. Automation of all components of PCR is now possible, which will decrease the risk of generating false-positive results due to contamination. The novel real-time PCR strategy and clinical applications in equine infectious diseases will be the subject of this review. [source] Validation of DNA probes for preimplantation genetic diagnosis (PGD) by fluorescence in situ hybridization (FISH) R1PRENATAL DIAGNOSIS, Issue 11 2006Stanislawa Weremowicz Abstract Background Preimplantation genetic diagnosis (PGD) by fluorescence in situ hybridization (FISH) is being employed increasingly by medical centers and private companies. Validation of any clinical assay, particularly one with novel applications such as PGD by FISH, is of critical importance in the clinical setting. This importance is recognized by both the College of American Pathologists (CAP) and the American College of Medical Genetics (ACMG), who recommend validation of FISH assays in the clinical setting. Validation of FISH assays for PGD is especially significant, as only one or two cells (blastomeres) will be available for testing of a given embryo. Methods We have developed validation protocols for a variety of FISH assays, including sex identification, structural chromosomal aneusomy, and aneuploidy screening with the Vysis, Inc., PGT probe panel. Results Our validation results show good individual performance of commercially available probes, and decreasing overall efficiency as the number of probes included in an assay increases. Copyright © 2006 John Wiley & Sons, Ltd. [source] Microbial contaminants in food: a big issue for a working group of the MoniQA NoE projectQUALITY ASSURANCE & SAFETY OF CROPS & FOOD, Issue 2 2009A. Hoehl Abstract Introduction The MoniQA Network of Excellence is an EC funded project working towards the harmonization of analytical methods for monitoring food quality and safety along the food supply chain. This paper summarises both the structure and tasks of the working group on microbial contaminants within the MoniQA NoE and specifically focuses on harmonisation strategies important in the microbiological analysis of food. Objectives There is a need for rapid microbiological methods in order to quickly and efficiently identify harmful pathogens in food sources. However, one of the major problems encountered with many new methods is their market acceptance, as they have to pass extensive validation/standardisation studies before they can be declared as official standard methods. Methods The working group on microbiological contaminants aims to contribute towards speeding up these prerequisites by collecting information on food law, quality assurance, quality control, sampling, economic impact, measurement uncertainty, validation protocols, official standard methods and alternative methods. Results The present report provides an overview of currently existing methodologies and regulations and addresses issues concerning harmonisation needs. One of the deliverables of the working group is the development of extended fact sheets and reviews based on relevant ,hot' topics and methods. The selection of food borne analytes for these fact sheets have been selected based on global, local and individual parameters. The working group has identified 5 groups of stakeholders (governmental bodies, standardisation/validation organisations, test kit/equipment manufacturers, food industry and consumers). Conclusion Current challenges of food microbiology are driven by new analytical methods, changes in the food market and altered consumer desires. The MoniQA NoE is contributing in overcoming these risks and challenges by providing a profound platform on microbiological rapid methods in food analysis to all stakeholders and it is expected that strong interaction within the network and beyond will foster harmonization. [source] On the use of logarithmic scales for analysis of diffraction dataACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2009Alexandre Urzhumtsev Predictions of the possible model parameterization and of the values of model characteristics such as R factors are important for macromolecular refinement and validation protocols. One of the key parameters defining these and other values is the resolution of the experimentally measured diffraction data. The higher the resolution, the larger the number of diffraction data Nref, the larger its ratio to the number Nat of non-H atoms, the more parameters per atom can be used for modelling and the more precise and detailed a model can be obtained. The ratio Nref/Nat was calculated for models deposited in the Protein Data Bank as a function of the resolution at which the structures were reported. The most frequent values for this distribution depend essentially linearly on resolution when the latter is expressed on a uniform logarithmic scale. This defines simple analytic formulae for the typical Matthews coefficient and for the typically allowed number of parameters per atom for crystals diffracting to a given resolution. This simple dependence makes it possible in many cases to estimate the expected resolution of the experimental data for a crystal with a given Matthews coefficient. When expressed using the same logarithmic scale, the most frequent values for R and Rfree factors and for their difference are also essentially linear across a large resolution range. The minimal R -factor values are practically constant at resolutions better than 3,Å, below which they begin to grow sharply. This simple dependence on the resolution allows the prediction of expected R -factor values for unknown structures and may be used to guide model refinement and validation. [source] | ||||||||||