BackgroundThe potential problems associated with the use of formalin in histology, such as health hazards, degradation of RNA and cross-linking of proteins are well recognized. We describe the utilization of a formalin-free fixation and processing system for tissue detection of two important biopredictors in breast cancer – estrogen receptor and HER2 – at the RNA and protein levels.MethodsParallel sections of 62 cases of breast cancer were fixed in an alcohol-based molecular fixative and in formalin. Molecular fixative samples were processed by a novel formalin-free microwave-assisted processing system that preserves DNA, RNA and proteins. Formalin-fixed samples were processed using the conventional method. Estrogen receptor was assessed by immunohistochemistry and real-time PCR. HER2 was assessed by immunohistochemistry, FISH, CISH and real-time PCR.ResultsThe immunohistochemical reaction for estrogen receptor was similar in molecular- and formalin-fixed samples (Spearman Rank R = 0.83, p < 0.05). Also HER2 result was similar to that of formalin-fixed counterparts after elimination of antigen retrieval step (Spearman Rank R = 0.84, p < 0.05). The result of HER2 amplification by FISH and CISH was identical in the molecular fixative and formalin-fixed samples; although a shorter digestion step was required when using the former fixative. Real-time PCR for both estrogen receptor and HER2 were successful in all of the molecular fixative specimens.ConclusionThe formalin-free tissue fixation and processing system is a practical platform for evaluation of biomolecular markers in breast cancer and it allows reliable DNA and RNA and protein studies.

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Array-based comparative genomic hybridization (a-CGH) is a promising tool for clinical genomic studies. However, pre-analytical sample preparation methods have not been fully evaluated for this purpose. Parallel sections of normal male human skin biopsy samples were collected and immediately immersed in saline, formalin and a molecular Wxative for 8, 12 and 24 h. Genomic DNA was isolated from the samples and subjected to ampliWcation and labeling. Labeled samples were then co-hybridized with normal reference female DNA to Agilent oligonucleotide-based a-CGH 44k slides. Pre-analytic parameters such as DNA yield, quality of genomic DNA and labeling eYcacy were evaluated. Also microarray analytical variables, including the feature signal intensity, data distribution dynamic range, signal to noise ratio and background intensity levels were assessed for data quality. DNA yield and quality of genomic DNA-as evaluated by spectrophotometry and gel electrophoresis-were similar for fresh and molecular Wxative-exposed samples. In addition, labeling eYcacy of dye incorporation was not drastically diVerent. There was no diVerence between fresh and molecular Wxative material comparing scan parameters and stem plot analysis of a-CGH result. Formalin-Wxed samples, on the other hand, showed various errors such as oversaturation, non-uniformity in replicates, and decreased signal to noise ratio. Overall, the a-CGH result of formalin samples was not interpretable. DNA extracted from formalin-Wxed tissue samples is not suitable for oligonucleotide-based a-CGH studies. On the other hand, the molecular Wxative preserves tissue DNA similar to its fresh state with no discernable analytical diVerences.

La encefalopatía traumática crónica (ETC) es una enfermedad neurodegenerativa que se produce como consecuencia traumatismoscerebrales repetitivos; concusiones, que son un síndrome clínico que se caracteriza por una alteración de la función cerebral5. Una concusión, bajo su estricta definición, no debiese causar cambios estructurales en el cerebro por lo que no sería visible a través de imágenes, sí existen cambios a nivel microscópicos, bioquímicos y biomecánicos1. La mayoría de los pacientes tienen completa resolución de sus síntomas dentro de 10 días (90%), pero existe un pequeño porcentaje que persiste con estos8, pudiendo presentarse como un síndrome postconcusional, síndrome de segundo impacto o una encefalopatía traumática crónica3. La ETC se caracteriza por la acumulación de prot-tau hiperfosforilada en neuronas y astrocitos2. Estas se van a presentar en forma de ovillos o hilos neurofibrilares. En etapas iniciales las encontraremos de forma focalizada en la corteza frontal y en las formas más severas su distribución será más generalizada, distribuyéndose en la mayoría de las regiones del cerebro9. Su diagnóstico se realiza a través de histopatología, por lo que hasta el momento sólo se ha logrado post-mortem. Se está trabajando en nuevas tecnologías asociadas a biomarcadores y PET para lograr una diagnostico premortem. El mayor énfasis en el manejo de esta taupatía es la prevención y adecuado manejo de las concusiones.