1 The influence of NG-nitro-L-Arginine (L-NNA) on non-adrenergic non-cholinergic (NANC) relaxations induced by electrical field stimulation was investigated in circular muscle strips of the guinea-pig gastric fundus. 2 In the presence of 106 M atropine and 4 x 106 M guanethidine, electrical field stimulation (40 V, 1 ms, 0.125-16 Hz) with 10 s trains at 5 min intervals induced short-lasting, frequency-dependent relaxations. Continuous stimulation, with cumulative increase of the stimulation frequency, induced sustained frequency-dependent relaxations. Both types of response were abolished by 3 x 10-6 M tetrodotoxin. 3 L-NNA (10-5M and 10-4M) concentration-dependently reduced both types of NANC response. Pre-incubation with 2 x 10-3M L-arginine prevented the inhibitory action of 10-5M L-NNA and partially antagonized that of I0-4 M L-NNA. D-arginine (2 x I0-3 M) did not protect against the inhibitory effect of L-NNA. 4 L-NNA did not consistently influence the basal tone of the tissues. L-Arginine and D-arginine likewise did not influence basal tone; they also had no influence on the electrically-induced NANC relaxations.5 NO (0-6 10-4 M) induced short-lasting concentration-dependent relaxations, while vasoactive intestinal polypeptide (VIP, (10--10-M) induced more sustained relaxations, that developed at a slower rate. The NO-and VIP-induced relaxations were not influenced by 10-4 M L-NNA. 6 These results suggest that NO is involved in NANC neurotransmission of the guinea-pig gastric fundus; its contribution to sustained NANC relaxation in the guinea-pig gastric fundus is much more important than in the rat.
Between 1991 and 2000, seven patients presented with symptomatic pineal cysts at our hospital (6 females, 1 male). Average age was 22 years (range 4-33 years). Headache was present in 6 patients, who were subsequently operated on. A scotoma and a transient inferior visual field deficit were minor signs in two patients respectively. A Parinaud syndrome with vertical gaze paralysis was found in none. In one child, paroxysmal pupillary dilatations and contractions ('springing pupils') constituted the only signs and a conservative policy was adopted. Four patients presented with hydrocephalus and were treated by an endoscopic resection of their pineal cysts (one stereotactically, three free-hand). Two other patients presented with a prolonged history of symptoms and signs: headache alone in one, headache with discrete neurological deficits in the other. Ventricles in these two patients were not dilated and therefore an open cyst resection by infratentorial supracerebellar approach was performed. Average follow-up in the six "operated" patients was 29 months (range 12-108 months). All four patients treated by endoscopy, are symptom-free at follow-up, whereas the two who were approached by open surgery, are not. Clinical presentation, radiological evaluation and treatment modalities of pineal cysts are discussed and compared with experiences reported in the literature. It is concluded that pineal cysts in the presence of obstructive hydrocephalus are a clear indication for endoscopy with a rigid endoscope.
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