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The excitatory responses of neurones in the anterior cingulate cortex of the rat to iontophoretically applied substance P (SP) are reduced by noradrenaline (NA) applied iontophoretically or released from noradrenergic pathways. In order to determine the receptor involved in this inhibitory effect we have studied the effects of a number of receptor-specific adrenergic agonists and antagonists on responses of cingulate neurones to SP in rats anaesthetized with chloral hydrate. Low iontophoretic currents (0-15 nA) of NA, adrenaline and the beta-agonist, clenbuterol, all strongly reduced responses to SP. Isoprenaline was also effective but less consistently so, although problems were experienced with its iontophoretic release from micropipettes. The alpha 1-agonists, phenylephrine and methoxamine were also able to reduce responses to SP. However, this reduction required higher iontophoretic currents (15-60 nA) and was associated with depressant effects on baseline firing rate. The alpha 2-agonist clonidine was only weakly active at high currents and this too was associated with depression of baseline firing. Similar weak effects were noted with dopamine. The inhibitory effects of NA on SP responses were convincingly blocked or reversed by the beta-antagonist, practolol, but not by the alpha 1-antagonist, prazosin. The reduction of SP responses by phenylephrine was also blocked by practolol but unaffected by prazosin. Finally, reduction of SP excitations by activation of the coeruleocortical pathway was also blocked by practolol applied iontophoretically to the cortical cells. These results are consistent with the hypothesis that the effect of NA on SP responsiveness in the cingulate cortex is mediated by beta-adrenoreceptors. 相似文献
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Long-term effects of cochlear implants in children. 总被引:5,自引:0,他引:5
Susan B Waltzman Noel L Cohen Janet Green J Thomas Roland 《Otolaryngology--head and neck surgery》2002,126(5):505-511
OBJECTIVE: Since 1987, when the use of multichannel cochlear implants was initiated in children, candidacy has expanded; many thousands of children have received these devices, and results have revealed a wide range of performance. However, few long-term studies exist on a large population of these children. There have been concerns expressed that cochlear implant function might degrade over time, that devices and electrodes might migrate and extrude in the growing child, or that there might even be a deleterious effect of long-term stimulation of the cochlear nerve. The purpose of this study was to explore the long-term effects of implantation as a function of performance over time, reimplantation, and educational factors. STUDY DESIGN AND SETTING: We studied 81 children who received implants at a major academic medical center and were followed for 5 to 13 years. RESULTS: Results revealed significant gains in speech perception, use of oral language, and ability to function in a mainstream environment. There was no decrease in performance over time and no significant incidence of device or electrode migration or extrusion, and device failure did not cause a deterioration in long-term outcome. CONCLUSIONS: Multichannel cochlear implants in children provide perception, linguistic, and educational advantages, which are not adversely affected by long-term electrical stimulation. 相似文献
46.
The purpose of this article is to determine if any change has occurred in the role labyrinthectomy plays in the therapeutic armamentarium of members of the American Neurotologic Society. Questionnaires were sent to all members and 42% of these were returned. Analysis of the questionnaires suggests that labyrinthectomy still remains an important tool in the surgical management of vertigo, although it is less frequently employed now than 10 years ago. This seems to be the consequence of increased valuation of even minimal levels of residual hearing. 相似文献
47.
48.
Value of grading squamous cell carcinoma of the head and neck. 总被引:3,自引:0,他引:3
We report a series of 3,294 patients with squamous cell carcinoma of the head and neck seen by one of us between 1963 and 1990. Two thousand and seven patients had a histologically proven and graded, but previously untreated, squamous cell carcinoma of the mucosal surfaces of the head and neck. These tumors had been graded previously by many different pathologists in many different hospitals, both in the United Kingdom and the United States, as well as continental Europe, over this period. Of the host factors both sex and age were associated with differentiation: 34% of patients less than age 50 had a well-differentiated tumor compared with 44% greater than age 50; 32% of women had a poorly differentiated tumor compared with 26% of men. General condition had no correlation with degree of differentiation. Site was closely associated with grading: well-differentiated tumors were more common in the mouth and larynx and poorly differentiated tumors in the pharynx. Furthermore, of poorly differentiated tumors, 19% arose from areas normally lined by keratinized squamous epithelium, 22% from a nonkeratinized area, 36% from respiratory epithelium, and 45% from areas normally covered by lymphoid epithelium. T stage had no significant correlation with differentiation. However, 46% of patients with poorly differentiated tumors had a nodal metastasis at presentation compared with only 28% of well-differentiated tumors. Distant metastases at presentation were found in 3.4% of poorly differentiated tumors compared with 1.8% of well-differentiated tumors. The survival fell significantly from 33% for well-differentiated tumors to 27% for poorly differentiated tumors. The recurrence rate at the primary site rose from 25% for well-differentiated tumors to 27% for poorly differentiated tumors, and recurrence in the lymph nodes rose from 26% to 30%. Both differences were just significant. 相似文献
49.
Norbert Boos Daniel Dreier Esther Hilfiker Volker Schade Roland Kreis Josef Hora Max Aebi Chris Boesch 《Journal of orthopaedic research》1997,15(1):141-149
The purpose of this investigation was to determine differences in tissue composition of symptomatic and asymptomatic disc herniations as reflected in T1 and T2 relaxation times (quantitative magnetic resonance investigation of the lumber spine. The longitudinal and transverse magnetic rlaxation times (T1 and T2, respectively) were calculated from a set of 20 images obtained with five single-slice/multi-echo sequences at different repetition time values on a commercial whole-body system (1.5 T). Twenty-two symptomatic and asymptomatic disc herniations could be matched according to age, gender, disc level, and the extent of herniation (protrusion or extrusion) and were compared with regard to T1 and T2 relaxation times. Symptomatic disc herniations exhibited significantly (pT1 < 0.04 and pT2 < 0.003) shorter T1(ΔT1:–182.1 milliseconds, ?15%) and T2(ΔT2: ?11.0 milliseconds, ?21%) relaxation times than matched asymptomatic herniations. Symptomatic disc herniations also exhibited more advanced disc degeneration as graded by Pearce's criteria (p < 0.01). These results suggest that symptomatic and morphologically matched asymptomatic disc herniations differ with regard to disc matrix composition. 相似文献
50.
S. Uhlig Roland Lewis Featherstone 《Naunyn-Schmiedeberg's archives of pharmacology》1997,356(3):392-397
To gain more insight into the complex pulmonary interactions of endothelins (ET), we studied airway and vascular responses
to endothelins in isolated perfused rat lungs in the presence of the novel ETB-receptor antagonist BQ788. In particular we focused on airway responses and on prostacyclin release. The effectiveness of
BQ788 in our system was shown by its ability to concentration-dependently prevent vasoconstriction (IC50 0.1μM), bronchoconstriction (IC50 0.1μM) and prostacyclin production (IC50<0.1μM) induced by the ETB-receptor agonist IRL1620 (1nmol). Airway responses to ET-1: ET-1-induced bronchoconstriction was aggravated by BQ123 (1 or
8μM), while BQ788 pretreatment (1 or 8μM) showed no significant effect. Simultaneous treatment with 8μM BQ123 and BQ788 attenuated
the ET-1-induced bronchoconstriction. Vascular responses to ET-1: ET-1 (1nmol)-induced vasoconstriction was potentiated by
BQ788 (1 or 8μM), but attenuated by the ETA-receptor antagonist BQ123 (1μM). In the presence of BQ788 diminished amounts of the stable prostacyclin metabolite 6-keto-PGF1α were detected in the perfusate. Simultaneous treatment with 8μM BQ123 and BQ788 completely prevented the ET-1-induced vasoconstriction.
Conclusions: Both ETA- and ETB-receptors contribute to ET-1-induced vasoconstriction and bronchoconstriction. The ET-1-induced vasoconstriction is attenuated
by stimulation of ETB-receptors, a response that is partly mediated by prostacyclin. Due to the mutual interactions between ETA- and ETB-receptors, simultaneous inhibition of both receptors is required to prevent the deleterious effects of ET-1 on lung functions.
Received: 17 October 1996 / Accepted: 16 May 1997 相似文献