RESUMEN
Electrical stimulation of the retina elicits visual perception in patients with retinitis pigmentosa. Using the potentials of microsystem technology, neural prostheses to restore vision become feasible that are completely implantable in the eye. In this paper, we describe the development of an inductively coupled epiretinal vision prosthesis. Microelectronic chips for data encoding and stimulation were assembled on flexible substrates with an integrated electrode array. The system was encapsulated with parylene C and silicone rubber. The receiver part was placed into an artificial intraocular lens. Microcables led to the stimulation array in the macula region. This prototype elicited spatio-temporal patterns in the visual cortex after electrical stimulation of the retina in the cat.
RESUMEN
Leaves, roots and rhizomes, and inflorescenses of Pulmonaria obscura from two localities and of two different growth forms within one site were analyzed by GC-MS for their content in pyrrolizidine alkaloids (PAs). In roots and rhizomes PAs of the lycopsamine type typical for the Boraginaceae could be detected, e. g. intermedine, lycopsamine, and their O(7)-derivatives. The total PA concentrations in roots and rhizomes lay between 0.026 and 0.158 mg/g dry weight. In leaves and inflorescenses, on the other hand, only trace amounts of PAs (below 0.4 ng/mg dry weight) could be detected. No significant differences in total concentration of PAs could be found between the two sites.