Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
5.
Exp Brain Res ; 128(3): 383-9, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10501810

RESUMO

In order to assess the autoinhibitory control of endogenous acetylcholine (ACh) in rat and human neocortex, slices of these tissues were prelabelled with [(3)H]choline, superfused continuously and stimulated electrically using various frequencies in the presence or absence of drugs. The autoinhibitory feedback control of [(3)H]ACh release was operative - despite the absence of blockers of ACh esterase - at stimulation frequencies >/= 3 Hz in rat and >/= 6 Hz in human neocortex tissue. At these frequencies the muscarinic antagonist atropine (0.1 microM) disinhibited the release of [(3)H]ACh in both species. Estimation of the biophase concentration of ACh near the autoreceptor in the rat neocortex from concentration-response curves of the muscarinic agonist oxotremorine revealed that at 3 Hz about 25% of the autoreceptors were activated by endogenously released ACh. This estimation is consistent with an increase in [(3)H]ACh release to about 120% of control values by complete blockade of autoreceptors with atropine. The observation that in human neocortical tissue presynaptic autoinhibition of [(3)H]ACh release is operative at stimulation frequencies >/= 6 Hz suggests that selective blockade of autoinhibition may also increase ACh release in the cortex of Alzheimer's disease patients, without additional blockade of the enzyme acetylcholinesterase.


Assuntos
Acetilcolina/metabolismo , Atropina/farmacologia , Proteínas de Transporte/efeitos dos fármacos , Proteínas de Membrana Transportadoras , Antagonistas Muscarínicos/farmacologia , Neocórtex/efeitos dos fármacos , Proteínas de Transporte Vesicular , Acetilcolina/fisiologia , Idoso , Doença de Alzheimer/tratamento farmacológico , Animais , Proteínas de Transporte/fisiologia , Estimulação Elétrica/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Agonistas Muscarínicos/farmacologia , Antagonistas Muscarínicos/uso terapêutico , Neocórtex/metabolismo , Oxotremorina/farmacologia , Ratos , Transmissão Sináptica , Proteínas Vesiculares de Transporte de Acetilcolina
6.
Neuroradiology ; 41(8): 584-7, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10447570

RESUMO

We report an intramedullary angiolipoma with spinal cord compression studied by MRI, angiography and CT. Angiolipomas of the spine are rare benign tumours containing vascular and mature adipose elements. They are epidural in more than 90 % of the cases; only three cases of intramedullary angiolipoma are described. The clinical picture is nonspecific, but MRI and CT suggest the diagnosis.


Assuntos
Angiolipoma/diagnóstico , Neoplasias da Coluna Vertebral/diagnóstico , Adulto , Angiolipoma/diagnóstico por imagem , Vértebras Cervicais/diagnóstico por imagem , Vértebras Cervicais/patologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Compressão da Medula Espinal/etiologia , Neoplasias da Coluna Vertebral/diagnóstico por imagem , Vértebras Torácicas/diagnóstico por imagem , Vértebras Torácicas/patologia , Tomografia Computadorizada por Raios X
8.
Radiology ; 211(1): 169-75, 1999 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10189467

RESUMO

PURPOSE: To evaluate polyethylene terephthalate and polyurethane as coatings of vascular endoprostheses in the treatment of experimental arteriovenous fistulas (AVFs). MATERIALS AND METHODS: Nineteen bilateral carotid artery-to-external jugular vein AVFs were created in 10 adult dogs. Fourteen polyethylene terephthalate-coated and five polyurethane-coated self-expandable nitinol stents were placed with a transfemoral approach. Angiography was performed immediately after placement, after 1 and 3 weeks, and at months 3, 6, 9, and 12. All grafts were examined histopathologically. RESULTS: The AVF was successfully occluded with all but one of the polyethylene terephthalate-coated stents. Graft patency was seen with 12 polyethylene terephthalate-coated stents, while acute vessel occlusion was evident with two polyethylene terephthalate-coated stents following percutaneous transluminal angioplasty immediately after implantation. In the group with polyurethane-coated stents, three graft dislocations and two delayed vessel occlusions were observed. In both groups, histologic examination disclosed a mild foreign body reaction with a few macro-phages. No inflammatory reactions were seen. An unorganized fibrin layer was found adjacent to the polyurethane coating. CONCLUSION: Polyethylene terephthalate-coated nitinol stents showed good biocompatibility and a high rate of occlusion of experimental AVFs. The mechanical properties of the polyethylene terephthalate coating were similar to those of the nitinol stents, which facilitated handling. Polyurethane-coated stents showed frequent dislocation.


Assuntos
Ligas , Fístula Arteriovenosa/terapia , Materiais Revestidos Biocompatíveis , Polietilenotereftalatos , Poliuretanos , Stents , Animais , Fístula Arteriovenosa/diagnóstico por imagem , Fístula Arteriovenosa/etiologia , Artéria Carótida Primitiva , Cães , Veias Jugulares , Radiografia
10.
Acta Neuropathol ; 72(4): 402-5, 1987.
Artigo em Inglês | MEDLINE | ID: mdl-3577695

RESUMO

The effect of a selective irradiation of myelin by 3H beta-particles was studied by light and electron microscopic methods in guinea pig spinal cord. The animals were injected with [3H]leucine shortly after birth when the rate of myelin biosynthesis is high and sacrificed 130 days later. In spinal cord the radioactivity was mainly preserved in myelin because the half life of myelin proteins is much higher than that of most other CNS proteins. As a consequence the irradiation dose in the white matter was much higher than in the gray matter. In myelin internally irradiated by 3H beta-particles within 130 days at a dose of 10 Gy no alterations could be detected either by morphological or by morphometric methods.


Assuntos
Bainha de Mielina/efeitos da radiação , Medula Espinal/efeitos da radiação , Trítio/efeitos adversos , Animais , Animais Recém-Nascidos , Partículas beta , Cobaias , Leucina , Bainha de Mielina/fisiologia , Medula Espinal/crescimento & desenvolvimento
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...