ISO 20184-2:2018 pdf free

ISO 20184-2:2018 pdf free.Molecular in vitro diagnostic examinations一Specifications for pre-examination processes for frozen
tissue
All steps of a diagnostic workflow can influence the final analytical test result. Thus, the entire workflow including biomolecule stability and sample storage conditions shall be verified and validated.Workflow steps which cannot always be controlled (e.g. warm ischemia) shall be documented. A risk assessment of non-controllable workflow steps including their potential impact on the examination test performance shall be performed and mitigation measures shall be established to enable the required examination test performance.
The stability of the specific proteins to be examined and their posttranslational modifications (if important for the assay) should be investigated throughout the complete pre-examination process prior to the development and implementation of an examination test (e.g. by performing a time course experiment or study; see also Annex A and Reference [8]).
Before tissues are stabilized by freezing, protein amounts, conformations and binding status can change e.g. by protein degradation and altered synthesis following gene induction, gene down regulation, RNA degradation, and changes of the biochemical pathway and energy status. These effects depend on the duration of warm and cold ischemia and the ambient temperature before freezing. In addition, the described effects can vary in different donors’/patients’ tissues.
Generally, the longer the duration of warm and cold ischemia and the higher the ambient temperature before freezing the tissue specimen, the higher is the risk that changes in the protein profile can occur.
NOTE Prolonged cold ischemia durations result in changes of protein (e.g. cytokeratin 18) and phosphoprotein (e.g. phospho-p42/44) amounts[8][2]. Keeping the specimen on wet-ice diminishes this effect[1Q].
Protein amounts as well as posttranslational modifications can also vary during the pre-examination phase,depending on the origin and type of tissue, the underlying disease, the surgical procedure, the drug regimen,and drugs administered for anaesthesia or treatment of concomitant disease and on the different environmental conditions after the tissue removal from the body.
As warm ischemia cannot be easily standardized, its duration shall be documented. When it is not possible to avoid cold ischemia, its duration shall be documented and temperatures of the specimen container’s surroundings shall be documented. Where the specimen is transported to another facility for freezing, the transport duration shall be documented and the ambient conditions should also be
documented.ISO 20184-2 pdf free.