To elucidate the synthetic activity in relation to the morphology of the epithelial cells of the small and large intestine, in situ hybridization with a poly-deoxyribothymidine (poly d(T)) probe was ...applied to paraffin sections of formalin-fixed blocks. This effectively displays poly-adenylated RNA and, by implication, messenger RNA (mRNA). By minimizing proteinase K pretreatment, the relative concentrations of cellular mRNA were visualized. This revealed minimal mRNA in crypt columnar cells, and maximal mRNA in proliferating cells and in cells showing terminal differentiation. The latter include surface epithelial cells, endocrine cells, Paneth cells, and maturing, but not mature, goblet cells. The goblet cells showing positive hybridization can be regarded as active cells and show characteristic morphology. Such cells are particularly evident in untreated coeliac disease, remitting ulcerative colitis, and transitional mucosa. The proliferating cells showing increased hybridization include normal mitotically active crypt epithelium, regenerating epithelium in ulcerative colitis, adenomatous epithelium, and adenocarcinomatous epithelium. The similarity of hybridization between metaplastic polyp epithelium and surface colonocytes is consistent with the concept that metaplastic polyps are formed of cells showing premature terminal differentiation.
Surface electroencephalogram (EEG) recording remains the gold standard for noninvasive assessment of electrical brain activity. It is the most efficient way to diagnose and classify epilepsy ...syndromes as well as define the localization of the epileptogenic zone. The EEG is useful for management decisions and for establishing prognosis in some types of epilepsy. Electroencephalography is an evolving field in which new methods are being introduced. The Canadian Society of Clinical Neurophysiologists convened an expert panel to develop new national minimal guidelines. A comprehensive evidence review was conducted. This document is organized into 10 sections, including indications, recommendations for trained personnel, EEG yield, paediatric and neonatal EEGs, laboratory minimal standards, requisitions, reports, storage, safety measures, and quality assurance.
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