Diffuse plaques

Neuritic or senile plaques are extracellular protein deposits of fibrils and amorphous aggregates of P-amyloid protein.11 This formed protein is central to the pathogenesis of AD. The P-amyloid protein is present in a non-toxic, soluble form in human brains. In AD, conformational changes occur that render it insoluble and cause it to deposit into amorphous diffuse plaques associated with dystrophic neuritis.14 Over time, these deposits become compacted into plaques and the P-amyloid protein becomes fibrillar and neurotoxic. Inflammation occurs secondary to clusters of astrocytes and microglia surrounding these plaques. 

Morris JC, Storandt M, McKeel DW, Rubin EH, Price JL, et al. 1996. Cerebral amyloid deposition and diffuse plaques in normal aging evidence for presymp-tomatic and very mild Alzheimer s disease. Neurology 46 707-19... 

Primary screening for antiviral activity was carried out using the agar-diffusion plaque-inhibition method with cylinders [65]. The compounds were tested against one representative in each of the four taxonomic viral groups namely, picoma-, orthomyxo-, paramyxo- and herpes viruses, which represent a few of the most important families of the human patogens. The viruses used were poliovirus 1 (PV1), influenza virus A (FPV), Newcastle disease virus (NDV) and pseudorabies virus (PsRV). 

There are two major forms of plaques neuritic and diffuse. Neuritic plaques are composed of extracellular deposits of Ap surrounded by dystrophic neurites. Diffuse plaques are amorphous extracellular deposits of AP-immunoreactive granular material that lack neurites, and are thought to precede neuritic plaques. 

Ay amyloid deposits occur in two morphological classes the non-fibrillar diffuse plaques, non-congophilic, or pre-amyloid which are not associated with significant neuronal pathology, and the mature fibrous senile or neuritic plaques (end-stages of the distinct a-amino-and y secretase pathways ). 

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