title: Autofluorescent chalcedony in human brains from elderly patients.
abstract: Chalcedony, a microcrystalline form of silica (SiO(2)), has been found in the human brains of elderly patients by using a standard optical petrographic microscope. We document here our visualization of chalcedony using a Leica TCS - SP2 confocal laser scanning microscope. Sections of human brain were collected after autopsy from elderly patients. The autofluorescent character of chalcedony allowed us to obtain three-dimensional images of the crystals and mature prismatic quartz (chalcedony) was observed. Chalcedony occurred as rhombohedral (trigonal) crystals approximately 30 microm in size distributed in patches or aggregates. A less mature silica polymorph of about 1- 2 microm in size was detected near the crystals. This is the first time that biogenically-produced crystalline mineral as autofluorescent crystal aggregates has been observed in the human central nervous system of elderly patients using confocal laser scanning microscopy.
authors.affiliation: Instituto de Investigaciones Bioquímicas de Bahía Blanca, CONICET/Universidad Nacional del Sur, LaCarrindanga km 7, CC 857, FWB8000 Bahía Blanca, Argentina. inprado@criba.edu.ar
authors.forename: M
authors.initials: M
authors.lastname: Prado Figueroa
authors.forename: J
authors.initials: J
authors.lastname: Sánchez Lihón
mesh_terms: D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology*; D001923:Brain Chemistry; D005453:Fluorescence; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D012825:Silicon / Q000737:chemistry*
chemical_list: D012825:Silicon