Autofluorescent chalcedony in human brains from elderly patients.

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.

Biosilicification (chalcedony) in human cerebral cortex, hippocampus and cerebellum from aged patients.

Aluminum and silicon have been observed to be present in the human degenerated brain and normal elderly brains by using a combination of scanning electron microscopy and X-ray spectrometry (EDS-SEM). Al and Si of electric organs were also reported--in electrocytes and cholinergic nerves--from living electric fish (family Rajidae). A biogenically produced crystalline mineral phase (i.

Chalcedony (a crystalline variety of silica): biogenic origin in electric organs from living Psammobatis extenta (family Rajidae).

The electric organs of electric fish have been used extensively for the study of peripheral cholinergic synapses. Aluminum and silicon have been observed in the electrocytes of Psammobatis extenta, a fish belonging to the family Rajidae, using a combination of scanning electron microscopy and X-ray spectrometry. Based on this evidence, the presence of silica minerals has been documented by means of mineralogical techniques.

SEM-EDS probing of morphological and physiological changes produced by a porphyrin photosensitizer in Psammobatis extenta electrocytes.

Morphological and physiological changes produced by the intracellular localization of an alkyl long-chain tetraphenylporphyrin photosensitizer in Psammobatis extenta electrocytes were studied by means of SEM-EDS. Immediately after photosensitizer penetration, electrocytes swell and their convex faces lose all invaginations. This effect is due to chloride and sodium ion flux into electrocytes, in accordance with energy dispersive X-ray microanalysis.

Intracellular localization of a long alkyl chain tetraphenylporphyrin and chloride channel activation in Psammobatis extenta electrocytes.

The intracellular localization of a tetraphenylporphyrin bearing four long lipophilic alkyl chains in electrocytes from Psammobatis extenta(Rajidae) is described. In contrast to what is usually the case, this porphyrin derivative is localized in the electromotor nerves and the nuclear chromatin of the electrocytes. Both structures exhibited intense fluorescence, whereas, the mitochondria were only slightly fluorescent.