AUTOFLUORESCENT AGGREGATES OF CHALCEDONY IN THE HUMAN BRAIN FROM

PRADO FIGUEROA, M.1; J SÁNCHEZ2 -

Búzios, RJ, Brazil

Congreso; I IBRO/LARC CONGRESS OF NEUROSCIENCES OF LATIN AMERICA, CARIBBEAN AND IBERIAN PENINSULA; 2008

IBRO/LARC Y SOC BRASILEIRA DE NEUROCIENCIA

C.01.108 Objectives.- Aluminum and silicon accumulations were detected in neurofibrillary tangle-bearing neurons and in normal elderly brains by a combination of scanning electron microscopy and X-ray spectrometry (EDS-SEM) (1). These inorganic elements are related to pathological changes in the cerebral cortex. The presence of chalcedony (SiO2) was also documented in the human brain, by using a petrographic microscope (2). Chalcedony is a microcrystalline fibrous form of silica consisting of nanoscale intergrowths of quartz and optically length-slow fibrous silica polymorph moganite (3). Based on this evidence we decided to document the presence of autofluorescent mineral chalcedony in autopsyderived brain tissue from aged patients (mean, 81 years) by using a Leica TSC – TS2 laser scanning confocal microscope (LSCM). Methods.- For these experiments, haematoxylin-eosin sections from routine neurohistologic preparations at the Pathology Department of the Instituto Nacional de Enfermedades Neoplásicas (INEN) Lima-Perú, were analyzed. Results.- A slight oversaturation of silicon is necessary for to allow chalcedony precipitation from the solution. Some quartz continues developing, forming large, euhedral overgrowths. Prismatic quartz belong to the rhombohedral crystal system, they are often twined or druse. Aggregates of prismatic quartz overgrowths are shown in this paper. These crystals show the characteristic autofluorescence with different excitation wavelengths, using a LSCM. Conclusions.- Fibrous minerals in biological environments generally grow either from an aqueous fluid in open spaces such cavities, or during retrograde metamorphism and alteration of preexisting minerals in the presence of an aqueous fluid. The fibrous habit of chalcedony might be worrisome for it can bind directly to DNA and cause DNA damage and neoplastic transformation. This is the first experimental evidence of biologically-produced crystalline silica mineral (chalcedony) and its degree of maturation, in human CNS from aged patients, using a LSCM. References: 1. Science 208: 297, 1980. 2. Micron, doi:10.1016/j.micron.2007.12.005. 3. Science 255: 441, 1982 Palavras-Chave: AChR, Neurodegeneration, Oxidative stress, Permineralization, Quartz, Silicon. Apoio Financeiro: This research was partially supported by grants given to María Prado Figueroa from the SGCyT, Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina. 412 412