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At least 1,063 records · Page 59Linked to original sources
PubMed1965

SOME OBSERVATIONS ON THE FINE STRUCTURE OF THE LATERAL LINE ORGAN OF THE JAPANESE SEA EEL LYNCOZYMBA NYSTROMI.

The fine structure of the lateral line organ of the Japanese sea eel Lyncozymba nystromi has been studied with the electron microscope. The sensory epithelium of the lateral line organ consists of a cluster of two major types of cells, the sensory hair cells and the supporting cells. The sensory cell is a slender element with a flat upper surface provided with sensory hairs, Two different types of synapses are distinguished on the basal surface of the receptor cell. The first type is an ending without vesicles and the second type is an ending with many vesicles. These are presumed to correspond to the afferent and the efferent innervations of the lateral line organ. The fine structure of the supporting cells and the morphological relationship between the supporting cells and the receptor cells were observed. The possible functions of the supporting cells are as follows: (a) mechanical and metabolic support for the receptor cell; (b) isolation of the individual receptor cell; (c) mucous secretion and probably cupula formation; (d) glial function for the intraepithelial nerve fibers. Both myelinated and unmyelinated fibers were found in the lateral line nerve. The mode of penetration of these fibers into the epithelium was observed.

Animals↗
PubMed2006

Adenosine test in the diagnosis of unexplained syncope: marker of conducting tissue disease or neurally mediated syncope?

Adenosine test (supine administration of a 20 mg intravenous bolus with electrocardiographic and blood pressure monitoring) has been endorsed by the European Society of Cardiology guidelines on syncope management as an 'experimental' test in the diagnosis of unexplained syncope. The test is quick and cheap, but there is no consensus as to what condition, if any, the adenosine test is exposing, with conducting tissue disease and neurally mediated syncope proposed by various authors. In this article, we review the possible mechanisms underlying a positive adenosine test, its safety, and a comprehensive examination of the literature supporting each of the putative causal diagnoses.

Adenosine↗
PubMed2003

Anterograde slow pathway is not the same as retrograde slow pathway conducted in the reverse direction in patients with uncommon atrioventricular nodal reentrant tachycardia.

INTRODUCTION: The aim of this study was to examine the location of anterograde and retrograde slow pathways in 16 patients with uncommon atrioventricular nodal reentrant tachycardia (AVNRT), including the fast-slow form in 10, slow-slow form in 5, and both fast-slow and slow-slow forms in 1. METHODS AND RESULTS: Patients were divided into two groups according to the approach used for slow pathway ablation in the initial radiofrequency catheter ablation (RFCA): one approach used earliest atrial activation during tachycardia (ES group, n = 9), and the other used a slow potential during sinus rhythm (SP group, n = 7). When the initial RFCA failed to eliminate slow pathway conduction in the ES group, an additional RFCA guided by a slow potential was performed. The ratio of lengths from the His-bundle region to the RFCA site and coronary sinus ostium (Abl/His-CS ratio) and the ratio of amplitudes of atrial and ventricular potentials at the RFCA site (A/V ratio) were compared between the two groups. In the initial RFCA, retrograde slow pathway conduction was eliminated without impairment of anterograde slow pathway conduction in 8 (89%) patients from the ES group, and bidirectional slow pathway conduction was eliminated in 6 (86%) patients from the SP group. Residual anterograde slow pathway conduction that was preserved after the initial RFCA in 8 of 9 patients was eliminated by an additional slow potential-guided RFCA. Both the Abl/His-CS ratio (0.86 +/- 0.07 vs 0.73 +/- 0.11, P = 0.01) and A/V ratio (0.80 +/- 0.31 vs. 0.14 +/- 0.01, P < 0.001) were higher in the ES group than the SP group. The ratios for the residual anterograde slow pathway ablation in the ES group were similar to those in the SP group. CONCLUSION: The results of this study suggest that the retrograde slow pathway runs more on the atrial side of the tricuspid valve annulus at the level of the coronary sinus ostium compared with the anterograde slow pathway, although both pathways run parallel or are fused in portions more proximal to the His bundle.

Adult↗
PubMed1983

The Croonian Lecture, 1983. Voltage-gated ion channels in the nerve membrane.

In the Croonian Lecture for 1957, Sir Alan Hodgkin described the role of the channels selective for sodium and potassium ions in the conduction of the nervous impulse. An essential feature of these channels is the manner in which the complex kinetics of their opening and closing is controlled by the electric field across the membrane, and the purpose of the present lecture is to consider the advances that have been made in the past 25 years towards an understanding of the underlying molecular mechanisms. One such advance has been the successful recording, independently of the ionic currents, of the small asymmetry current known as the gating current, that accompanies the conformational changes that take place in the sodium channels. A quantitative analysis of the characteristics of the gating current suggests that activation is brought about by two more or less independent processes operating in parallel, to one of which the slower mechanism of inactivation is coupled sequentially. However, it is clear that a complete picture of the gating system will only be arrived at by combining evidence of this kind with that provided by other new lines of approach such as studies of single ion channels in various tissues by means of fluctuation analysis and the patch-clamping technique, and a reinvestigation of the kinetics of activation of the potassium channels.

Anesthetics, Local↗