It was recently shown that supernormal conduction in the diseased His-Purkinje system is more common than previously thought, and is always associated with prolongation of refractoriness. To assess ...whether supernormal conduction could also occur in the accessory pathway of patients with ventricular pre-excitation, 21 patients with manifestly prolonged refractoriness in the accessory pathway were studied. Under these conditions, programmed atrial stimulation revealed a phase of supernormal conduction in 16 (76%) of the 21. Therefore, what was believed to be a nonexistent or exceptional physiologic event was shown to be a rather common finding, at least under certain circumstances. Supernormal conduction occurred in all 7 patients with an anterograde refractory period of 480 to 980 ms, and in 5 of 10 patients with a refractory period >1.0 second or with no anterograde conduction. Supernormal conduction could not be demonstrated in four patients with a refractory period ≤440 ms, but appearedin all four patients after the refractory period was prolonged by a rapid rate of stimulation or administration of ajmaline.
The electrophysiologic changes underlying the occurrence of supernormal conduction in the accessory pathway are similar to those previously reported for the bundle branch system. The demonstration of supernormal conduction in the accessory pathway may uncover the presence of concealed ventricular pre-excitation. Supernormal conduction over the accessory pathway may facilitate a rapid ventricular response during atrial fibrillation, even if the refractory period is prolonged.
An extensive literature links the immune responses to neuroendocrine regulation. We have examined the effects of the neuropeptide hormone angiotensin II on the production of the immunomodulatory ...lymphokine interferon-gamma (IFN-gamma). Angiotensin II (10(-6)-10(-8) M) stimulated (three- to fivefold) the IFN-gamma production in human blood lymphocytes obtained from normal individuals. At 10(-9) M angiotensin II stimulation disappeared and was reestablished at physiological concentrations of the neuropeptide (10(-10)-10(-11) M). Stimulation by angiotensin II was compared with the classical effect of the lectin phytohemagglutinin, and it was seen that both actions are mediated by external calcium (as they are blocked by EGTA 2.5 mM) and that the stimuli follow different kinetics, reaching the steady state at 6 h with angiotensin II and later (18 h) when the lectin was used. The effect of angiotensin II over the IFN-gamma production was blocked by its analog sarcosine 1-isoleucine 8-angiotensin II, showing the specificity of angiotensin II action. These findings demonstrate a selective biological regulation of IFN-gamma production by angiotensin II and suggest another regulation pathway of immune responses.
We observed that Sendai virus preinduction of peripheral blood mononuclear cells and subsequent mitogenic stimulation resulted in: (i) Superproduction of interferon-gamma, (IFN-gamma) (ii) an ...increase in interleukin-2 (IL-2) synthesis that correlates with DNA synthesis when stimulated with phytohemagglutinin (PHA) or pokeweed mitogen (PWM) after treatment with the Sendai virus, while stimulation with Protein A from Staphylococcus aureus was not affected, and (iii) enhanced tumor necrosis factor-alpha (TNF-alpha) production in response to bacterial lipopolysaccharide (LPS). Treatment of monocyte cultures with LPS and cycloheximide or actinomycin-D inhibited the superinduction phenomenon. When cycloheximide was added at the viral induction time, the inhibition of TNF-alpha superproduction and DNA synthesis was still observed. These results suggest that Sendai virus lymphocyte superinduction is specific for a particular stimulatory pathway, not dependent on mRNA accumulation, and probably mediated by induction of an activating protein.
O botulismo constitui uma forma rara de intoxicação alimentar, particularmente em nosso meio. A única epidemia comprovada desta doença no Brasil ocorreu na década de 1950, no Rio Grande do Sul, onde ...nove pessoas a adquiriram, após a ingestão de conserva caseira de peixe. O presente estudo relata um surto de Botulismo tipo A ocorrido em uma família de 8 membros, dos quais 7 contraíram esta toxinfecção após a ingestão de carne suína conservada sob a forma de enlatado caseiro. Duas pessoas evoluíram para o óbito, e os restantes recuperaram-se após variável tempo de evolução. Onze meses após, diagnosticou-se novo caso desta doença, cuja fonte da intoxicação não pôde ser detectada Os autores pretendem com esta publicação, divulgar a segunda epidemia comprovada de Botulismo no Brasil, e chamar atenção para seu quadro clínico, diagnóstico e tratamento, praticamente desconhecidos em nosso meio.
Caractérisation de la dispersion avec un modèle fractionnaire Cherifi, Mustapha; He, Ganming; Mastrangelo, Victor ...
Comptes rendus de l'Académie des sciences. Série II, Mécanique, physique, chimie, astronomie,
1998, 1998-1-00, Letnik:
326, Številka:
1
Journal Article
Nous utilisons un concept de dispersion fractionnaire pour analyser le régime de diffusion anormale, mis en évidence pour la dispersion d'un traceur dans une expérience hydrodynamique de ...Taylor-Couette. La diffusion anormale est caractérisée par un paramètre α (exposant de diffusion), égal à 2 pour la diffusion gaussienne. Les résultats de l'équation de convection-diffusion fractionnaire sont comparés aux courbes de distribution des temps de séjour de la concentration du traceur, et à ceux donnés par un modèle de convection-diffusion à quatre paramètres. L'exposant α, le coefficient de diffusion généralisé ainsi que la vitesse axiale de l'écoulement sont déterminés par ajustement.
We use the fractional dispersion concept to analyse the anomalous diffusion regime shown in a tracer dispersion in a hydrodynamical Taylor-Couette experiment. The anomalous diffusion is characterized with a parameter a (diffusion exponent), equal to two for the Gaussian diffusion. The results of the fractional advection-diffusion equa lion are compared to the concentration curves of the residence time distributions obtained in the experiment and to those from a coupled advection-diffusion model. The diffusion exponent, the generalized diffusion coefficient and the axial velocity are evaluated by fit.
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