An extension to: Systematic assessment of commercially available low-input miRNA library preparation kits.

High-throughput sequencing has emerged as the favoured method to study microRNA (miRNA) expression, but biases introduced during library preparation have been reported. We recently compared the performance (sensitivity, reliability, titration response and differential expression) of six commercially-available kits on synthetic miRNAs and human RNA, where library preparation was performed by the vendors. We hereby supplement this study with data from two further commonly used kits (NEBNext, NEXTflex) whose manufacturers initially declined to participate. NEXTflex demonstrated the highest sensitivity, which may reflect its use of partially-randomized adapter sequences, but overall performance was lower than the QIAseq and TailorMix kits. NEBNext showed intermediate performance. We reaffirm that biases are kit specific, complicating the comparison of miRNA datasets generated using different kits.

Caution on the storage of waters and aqueous solutions in plastic containers for hydrogen and oxygen stable isotope analysis.

RATIONALE: The choice of containers for storage of aqueous samples between their collection, transport and water hydrogen ((2)H) and oxygen ((18)O) stable isotope analysis is a topic of concern for a wide range of fields in environmental, geological, biomedical, food, and forensic sciences. The transport and separation of water molecules during water vapor or liquid uptake by sorption or solution and the diffusive transport of water molecules through organic polymer material by permeation or pervaporation may entail an isotopic fractionation. An experiment was conducted to evaluate the extent of such fractionation. METHODS: Sixteen bottle-like containers of eleven different organic polymers, including low and high density polyethylene (LDPE and HDPE), polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET), and perfluoroalkoxy-Teflon (PFA), of different wall thickness and size were completely filled with the same mineral water and stored for 659 days under the same conditions of temperature and humidity. Particular care was exercised to keep the bottles tightly closed and prevent loss of water vapor through the seals. RESULTS: Changes of up to +5‰ for δ(2)H values and +2.0‰ for δ(18)O values were measured for water after more than 1 year of storage within a plastic container, with the magnitude of change depending mainly on the type of organic polymer, wall thickness, and container size. The most important variations were measured for the PET and PC bottles. Waters stored in glass bottles with Polyseal™ cone-lined PP screw caps and thick-walled HDPE or PFA containers with linerless screw caps having an integrally molded inner sealing ring preserved their original δ(2)H and δ(18)O values. The carbon, hydrogen, and oxygen stable isotope compositions of the organic polymeric materials were also determined. CONCLUSIONS: The results of this study clearly show that for precise and accurate measurements of the water stable isotope composition in aqueous solutions, rigorous sampling and storage procedures are needed both for laboratory standards and for unknown samples.

Matrix elimination ion chromatography method for the determination of trace levels of anionic impurities in high purity cesium iodide.

In the present study an ion chromatographic method based on matrix elimination has been developed for the determination of anionic impurities in high purity cesium iodide crystals. The presence of impurities has a detrimental effect on the characteristics of detectors based on cesium iodide crystals. In particular, oxygen-containing anions inhibit the resolving power of scintillators and decrease the optical absorption. The quantitative determination of anions (fluoride, chloride, bromide, nitrate, phosphate, and sulphate) simultaneously in the high-purity cesium iodide crystals has not been carried out before. The large concentration of iodide poses a challenge in the determination of anions (especially phosphate and sulphate); hence, matrix elimination is accomplished by adopting a sample pretreatment technique. The method is validated for linearity, accuracy, and precision. The limit of detection for different anions is in the range of 0.3-3 µg/g, and the relative standard deviation is in the range of 4-6% for the overall method.

[The practical experience of quality control organization in the laboratory of Municipal consultative diagnostic center 1 of St. Petersburg].

The article specifies the functioning of quality control system in the laboratory of Municipal consultative diagnostic center i 1 of St. Petersburg. Initially, on the basis of interpretations of biological variations of every analyte, the requirements to analytical quality are developed. Subsequently, the actually attainable reproducibility of measurements and their bias is examined. The real analytical characteristics of 27 biochemical analytes are presented. The aggregate laboratory ratings are quoted based on the results of involvement in three EQAS programs since 2005, concerning biochemistry, immunochemistry and hematology. The important quality of laboratory research on its analytical stage is maintained by the interaction between inter-laboratory and regular external control.

Development of laboratory reference material: Soil 1. Baseline and highly elevated concentrations of metals and polycyclic aromatic hydrocarbons.

Reference materials play a key part in systems of inspection and quality control of results of analytical measurements. The main limitation in using certified reference materials (CRM) is their high price, which results from the long and costly process of producing the reference material. An alternative to costly CRM materials is the employment of laboratory reference materials, particularly for interlaboratory control of measurement results and procedures. Under the auspices of the Chair of Analytical Chemistry at the Chemical Department of Gdansk University of Technology, research on the development of new reference materials is being conducted. At present, the research is aimed at producing a new laboratory reference material (LRM): 'Soil 1. Baseline and Highly Elevated Concentrations of Metals and Polycyclic Aromatic Hydrocarbons' - LRM soil 1. This paper presents the production stages of the developed laboratory reference material: acquisition of raw material from soil samples taken from the environment of the Tri-city (in Polish, Trójmiasto Gdansk, Sopot, Gdynia) bypass road, homogenization and subsequent dosage into appropriate containers, tests of homogeneity of sampled material within one container and between containers, based on the results of the determination of selected parameters (total carbon, content of optional metals - Hg, Fe, Cu Zn, Mn, Mg, water content, content of PAH-group analytes). The obtained results of homogeneity tests of the proposed future laboratory reference material have confirmed the homogeneity of soil samples within a container and between containers. Currently, interlaboratory tests are being carried out to determine the reference value.

Intra-laboratory assessment of method accuracy (trueness and precision) by using validation standards.

Assessment of accuracy of analytical methods is a fundamental stage in method validation. The use of validation standards enables the assessment of both trueness and precision of analytical methods at the same time. Procedures of intra-laboratory testing of method accuracy using validation standards are outlined and discussed.

[Requirements for analytical quality: use of the concept of biological variation].

By using a clinical biochemistry laboratory as an example, the authors show how the analytical quality system practically operates. The advantages of using a three-level model for analytical quality requirements on the basis of biological variations in analytes are discussed. Only does the use of a few normative documents present a possibility of creating an adequate quality system in a specific laboratory. The long-term coefficient of analytical variation is the most important characteristic of analytical quality and a necessary component of the day-to-day work of the laboratory. The level of quality is shown for 27 analytes. Despite the fact that the laboratory uses the same analytical systems as in the world, the level of analytical quality has turned out to be lower than in the best laboratories of Europe.

[Recommendations for the selection of storage media for archiving digital radiological image data based on the comparison of retrieval times at different PACS archive levels]. / Empfehlungen zur Medienwahl für die Archivierung radiologischer Bilddaten auf der Basis einer Analyse der Zugriffszeiten auf verschiedene PACS-Archivebenen.

PURPOSE: Recommendations for archiving digital radiological image data based on the comparison of retrieval times for different PACS archive levels. MATERIALS AND METHODS: For a large PACS installation (Agfa Impax, Release 4.1), image retrieval times for radiological standard examinations (chest radiographs with 2, MRI with 250, CT with 100 and 1000 images; n = 120, each) from hard disk array, magneto-optical disk (MOD), and magnetic tape archives (TAPE) were examined in high and low network traffic load. RESULTS: Even large CT examinations (1000 images) were available from hard disk arrays within 4.0 +/- 0.8 s, smaller studies within 1.8 +/- 0.3 s. Radiographic image retrieval from MOD (30 +/- 4.7 s) was more then 50 % faster than from TAPE. For typical cross-sectional studies, the velocity gain amounted to 19 %. For both technologies, no significant difference was found for large CT examinations (651 +/- 144 s). For high and low network traffic load scenarios, image retrieval times from hard disk, MOD, and TAPE archives increased by 87 %, 7 %, and 22 %, respectively. CONCLUSION: Hard disk arrays are specifically suited as departmental intermediate storage media because they allow fast access to current and previous examinations within a short time. Performance properties enable both MOD and TAPE systems to serve as long-term archives. However, MOD archives are less flexible in the expansion of storage capacity and at present the medium costs per memory unit are about 2 - 3 times higher than for tape archives. The use of existing MOD-archives may be adequate as intermediate archives. For new PACS installations or system expansions, however, it is recommended to combine a sufficiently large local data memory (RAID) with data storage on tape archives outside the radiological unit that can be used by other departments as well. Future development of hard disk prices will show whether archiving for the whole data retention period may be handled by RAID systems. In any case, prefetching problems and waiting periods for demanded pre-studies would not occur any more.

Strategy for streamlined release identity testing of chromatography media.

In accordance with the US Code of Federal Regulations 21CFR 211.84 (6)(d)(1), a specific identity test must be performed for the release of chromatography media (stationary phase) before use in production of human pharmaceuticals. Due to the complexity of the physical and chemical properties of these media, i.e., variable particle morphology, insolubility, and chemical inertness, the development of specific identity tests presents a challenge. In this paper we report a new strategy for media identification that uses a combination of three relatively simple techniques: Fourier transform infrared (FT-IR) and near infrared (NIR) spectroscopy in conjunction with search libraries, and particle size distribution analysis. The methods are well established and suitable for routine application in a quality control laboratory. A hierarchical selection procedure utilizing these methods permits assignment of a unique identity for each of the chromatography media in use at a given facility, and form the basis of release tests for the media. Although this strategy was developed using specific media, the generic nature of the technology and the selection strategy proposed would permit its application to other chromatography media as well.

Controle de qualidade do minoxidil em laboratórios de pequeno porte / Quality control of minoxidil in compounding pharmacies

O minoxidil é um fármaco empregado no tratamento de hipertensão e da alopécia androgenética em homens e mulheres. Comercialmente, encontra-se sob a forma de comprimidos e de loção tópica. Observou-se que, para a preparação de loções com concentração superior a 2 por cento, tem sido empregado o sal do fármaco, devido à sua maior solubilidade. No entanto, esta molécula não possui patente e tampouco é citada na literatura. Objetivou-se propôr métodos alternativos para o controle de qualidade do minoxidil e confirmar a molécula descrita no laudo do fornecedor/fabricante do sulfato de minoxidil. Os testes qualitativos desenvolvidos (solubilidade, reações de cor/formação de precipitado e cromatografia em camada delgada) possibilitaram a identificação do minoxidil, bem como sua diferenciação do sulfato de minoxidil. Alterações na metodologia oficial do minoxidil permitiram a substituição da titulação potenciométrica pela detecção visual do ponto final, mantendo-se as características de exatidão e precisão. A molécula de sulfato de minoxidil foi devidamente caracterizada por testes de espectrometria de massas e espectrometria no infravermelho, sendo que a molécula informada pelo laboratório produtor foi confirmada. No entanto, os teores encontrados na análise quantitativa do fármaco não puderam ser confirmados, pela impossibilidade de comparação com métodos analíticos instrumentais, por inexistência de substância de referência.

[Harmonization criteria for inspection procedures. Italian Group for Quality Assurance in Research]. / Criteri di armonizzazione delle modalità ispettive. GIQAR.

In order to achieve higher levels of harmonisation for the application of the principles of good laboratory practice (GLP), the monitoring Authority has set up for the inspectors some guidelines to conduct inspections, as approved by the National co-ordination committee. The extension of these guidelines should allow for an improved application of the GLP principles taking into account actual situations detected during inspections carried out over the past years. In this respect a great number of observations formulated by the inspectors after inspecting several test facilities have been examined without revealing laboratories' and inspectors' identities. In addition to this, the observations made by the inspectors during the annual training course at the Istituto Superiore di Sanità in 2000 have been carefully considered.

"Ocean-to-Ocean Project": a transcontinental external quality assessment trial in clinical chemistry realized throughout Eurasia.

More than 800 diagnostic laboratories situated throughout the Eur-Asian continent--from the Pacific Coast up to the North Sea littoral--were involved in a common survey of External Quality Assessment (EQA). It consisted of the simultaneous measurement of up to 30 analytes of 'general' clinical chemistry using the same batch of control material. The laboratories were associated in four EQA institutions: SKZL (The Netherlands), OQUASTA (Austria), SEKK (Czech Republic) and BKKSystem (Community of Independent States). The results demonstrated the feasibility of such a large-scale survey and provided a realistic idea about the state-of-the-art of laboratory diagnosis in these countries: Besides some local specific problems, such as poor quality of water or the forced use of reagents and calibrators from different sources, there are general problems hindering an efficient process of 'harmonization' in laboratory medicine, namely, the high methodological dispersion especially in the case of enzymes and of some organic analytes. At the same time there is a potential necessity for more concentrated implementation of internal quality assessment into the routine work of laboratories.