[Orbital hemangiopericytoma in children].
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Biomedical subjects
Publications and source records attributed to A Rodallec.
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In vivo visualization of the optic nerve (ON) by computed tomography (CT) has important clinical applications, both realized and potential. An accurate CT analysis of the ON is, however, hampered by a number of technical limitations. Sinuosity and gaze-shift-related motility of the ON tend to increase the difficulties of demonstrating in a consistently satisfactory fashion this anatomical structure. Nevertheless, if rigid imaging criteria are followed, adequate visualization of the ON may be attained in the majority of patients. Simultaneous visualization of the ON and the eyeball permits establishment of a neuroocular index for clinical use.
Increase in the caliber and course tortuosity of the optic nerve (ON) can be demonstrated by computed tomography (CT) in cases of papilledema due to intracranial tumors, hydrocephalus, pseudotumor cerebri, and other conditions causing increased intracranial pressure. The enlargement of the ON in these conditions is generally bilateral, although one of the nerves, usually of the side of the tumoral pathology, may be thicker. Enlargement on the ON may also be demonstrated by CT in papilledema due to optic neuritis. Occasionally, the thickened ON also display increased attenuation coefficient values.
On normal isolated or stimulated Guinea-Pig myocardial strips, a polyflavane extracted from Poterium spinosum (Rosaceae) increased the duration of the action potential plateau phase. Such a modification was also elicited on hypoxic strips; in this case it did not depend on the glucose concentration in the medium; it could be related to an effect on the slow calcium-sodium channel.
The effects of 4-aminopyridine (4-AP) on guinea pig myocardial ventricular isolated strips were studied by means of intracellular microelectrodes. 4-AP increased the maximal depolarization velocity and decreased the effects of quinidine. In contrast to adrenaline, 4-AP antagonized the effects of MnCl1, but was ineffective against the alterations induced by a sodium poor solution. These findings support the suggestion that 4-AP modifies the electrophysiological membrane properties probably by increasing the Na+ inward current.