PubMed · 3842338
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J G Salway. 1985. Interference from drugs.. https://pubmed.ncbi.nlm.nih.gov/3842338/
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The 1H nuclear magnetic resonance (NMR) spectra of biological samples, such as blood plasma and tissues, are information rich but data complex owing to superposition of the resonances from a multitude of different chemical entities in multiple-phase compartments, hampering detection and subsequent resonance assignments. To overcome these problems, several spectral-editing NMR experiments are described here, combining spin-relaxation filters (based on T(1), T(rho), and T(2)) with both one-dimensional and two-dimensional (2D) NMR spectroscopy. These techniques enable the separation of NMR resonances based on their relaxation times and allow simplification of the complex spectra. In this paper, the approach is exemplified using a control human blood plasma, which is a complex mixture of proteins, lipoproteins, and small-molecule metabolites. In the case of T(1rho)- and T(2)-edited 2D NMR experiments, a "flip-back" pulse was introduced after the relaxation editing to make the phase cycling of the "relaxation filter" and the 2D NMR part independent, thus enabling easy implementation of the phase-sensitive 2D NMR experiments. These methods also permit much higher receiver gains to be used to reduce digitization error, in particular, for the small resonances, which are sometimes vitally important for metabonomics studies. Both pulse sequences and experimental results are discussed for T(1)-, T(1rho)-, and T(2)-filtered COSY, T(2)-filtered phase-sensitive DQF-COSY, and T(1), T(1rho)-, and T(2)-filtered TOCSY NMR.
Laboratory results play a key role in the diagnostic procedure, the decision of treatment and the follow up of diseases. A high validity of the laboratory result is an important precondition for the efficacy in clinical medicine. Analytical standards have been developed under strong quality control criteria, however, there are no sufficiently defined standards for the pre- and postanalytical phase in laboratory diagnostics. Thus, most of laboratory errors are caused by pre- and postanalytical mistakes. The competent knowledge of possible sources for laboratory errors is a critical precondition for their avoidance. Diagnostic sensitivity and specificity play an important role for the choice of a laboratory test, whereas the predictive value should be considered for the medical relevance of the test result. In addition, many interference factors, which may influence the results of the laboratory tests have to be considered as age, sex, race, lifestyle, drugs, pregnancy, specimen collection, quality and handling as well as special factors, which may influence the complex of immunological and molecular diagnostics.