BACKGROUND The preservation of optimized DNA and its extraction from formalin-fixed, paraffin-embedded (FFPE) tissues are important issues. There has been some doubt over whether 10% neutral-buffered formalin is an ideal fixation solution for DNA preservation over non-buffered formalin, as conventionally recommended. In this study, the correlation between the efficiency of DNA extraction from FFPE tissues and buffered formalin was evaluated. METHODS Several tissues with same conditions except fixatives were fixed in four different formalin solution groups and were routinely processed as paraffin-embedding protocols. DNAs were extracted from four different FFPE tissues that were stored for over 3 months and over 9 months. The quantity and quality of the DNAs were assessed with a NanoDrop ND-1000 spectrophotometer, and the polymerase chain reaction (PCR) amplification and degradation were analyzed via microchip electrophoresis.
KRAS mutation analysis and microsatellite instability (BAT25) PCR were performed with each sample. RESULTS The results showed no remarkable difference in the four groups. CONCLUSIONS The study findings demonstrate that DNA preservation is fairly unaffected by a neutral buffer where there is short formalin manufacture period and an adequate formalin fixation time before embedding in paraffin.
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The gross tissue specimens are a valuable aid to the teaching of pathology and anatomy. However, traditional methods for storage and handling of them are discouragingly difficult and, recently, minimal surgical resections as well as preoperative interventions make it more difficult to have instructive gross specimens. Plastination is a process of tissue preservation by impregnation with silicone polymers or epoxy resins. The process in our study involves dehydration by cryosubstitution in aceton, defatting, forced impregnation of silicon polymer in a vacuum, curing and finishing. We submitted 40 surgically resected specimens to plastination. The resulting specimens are odorless, relatively dry, durable, life-like, non-hazardous, maintenance-free, and do not deteriorate with time.
Plastinated specimens are a useful adjunct to the teaching of pathology, particularly suited for use in small groups, and appropriate method of tissue preservation. They are much preferred to wet preparation and conventional pots by both students and teachers owing to their accessibility, superior illustrative powers, and comparative ease of interpretation.