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V Cortés

Publications and source records attributed to V Cortés.

9 recordsLinked to original sources
PubMed1999

Synergism between neuropeptide Y and norepinephrine highlights sympathetic cotransmission: studies in rat arterial mesenteric bed with neuropeptide Y, analogs, and BIBP 3226.

Although abundant literature supports the notion that neuropeptide Y (NPY) synergizes in vivo and in vitro, the vasomotor activity elicited by norepinephrine (NE), the converse interaction (i.e., the adrenergic modulation of the NPY vasomotor response) has been less characterized. To assess whether NE synergizes the vasomotor effect of NPY, the rat arterial mesenteric bed was chosen as a model experimental system. Mesenteries were precontracted with NE and few minutes later were perfused with exogenous NPY. Under these conditions, NPY contracted the arterial mesenteric bed with an EC50 value of 0.72 +/- 0.06 nM. NPY was unable to contract this vascular territory without an agonist-induced precontraction. Other agonists, such as endothelin-1, a synthetic analog of prostaglandin F2alpha, or 5-hydroxytryptamine, also were effective primers because in their presence, NPY was a potent vasoconstrictor. In contrast, mesenteries precontracted with KCl failed to evidence the NPY-induced rise in perfusion pressure. Two structural analogs of NPY, PYY and [Leu31, Pro34]NPY, mimicked the activity of NPY. The NPY fragment 13-36 did not elicit such a response. All NPY analogs exhibited less efficacy and potency relative to NPY. The NPY- and related structural analog-induced vasoconstriction was competitively and reversibly antagonized by BIBP 3226; the pA2 of the NPY interaction was 7.0. The application of 0.1 to 1 microM BIBP 3226 or 0.1 to 10 nM prazosin at the peak of the NPY vasomotor response elicited a gradual blockade of the vasoconstriction. Although BIBP 3226 blocked the increase in perfusion pressure elicited by NPY, leaving unaffected the NE-induced tone, 10 nM prazosin blocked the full response, including the NE-induced component. Tissue preincubation with 200 nM nifedipine abolished the NPY-induced vasoconstriction; likewise, the acute application of 10 to 100 nM nifedipine blocked gradually the maximal NPY-induced contraction. Removal of the mesenteric endothelial layer increased the potency of NPY by 2-fold; it also slightly potentiated the antagonist activity of BIBP 3226. The synergism between NPY and NE backs the principle of sympathetic cotransmission.

Animals↗
PubMed1998

[Electroretinogram: technique and clinical applications].

INTRODUCTION: The retina is a neuronal membrane that covers the posterior part of the eye chamber and is formed by several layers. The retinal function can be synthesize as the light translation into nervous impulses in the optic nerve. MATERIAL AND METHODS: The ERG is the expression of the changes of the electrical potential in the retina after a luminous stimulus. There are different types of retinal stimulators specially flash, ganzfeld and pattern which are the most used in the clinical neurophysiological explorations. RESULTS: We expose the obtained responses, the morphology, amplitude and latencies of the (a) and (b) waves in scotopic and photopic conditions with ganzfeld or flash stimulator. In the ERG pattern we describe the waves for the transitory ERGP as well as for the Steady-State ERGP. We refer to the protocols proposed by the International Society of Electrophysiology of Vision (ISCEV). We mention the clinical applications of these techniques and we give our personal experience in diseases such retinitis pigmentosa, maculopathies, retinal degenerations, vascular diseases, cataracts and traumatic lesions of the retina.

Electric Stimulation↗
PubMed1997

[Partial simple vegetative crisis: importance of electroencephalographic findings].

INTRODUCTION: 50% of the patients with cerebral tumours present with epileptic crises, which may be partial or generalized. The commonest partial crises have motor symptoms. These make up 30% of the simple partial crises. Partial simple crises with purely vegetative-type symptoms are very uncommon (less than 5%). They are considered to be caused by discharges in the internal regions of the temporal lobes, mainly in the limbic system. This means that it is very difficult to identify them using techniques of surface EEG. CLINICAL CASE: We describe the case of a patient with a cerebral tumour. The initial clinical features were short episodes of generalized coldness and sweating which had been present for the previous two weeks, without any other symptoms. During a routine EEG, focal critical paroxystic activity was recorded in the right temporal region. This coincided with a clinical episode similar to those described. CONCLUSIONS: The episodes were labelled partial simple vegetative crises. In this case the EEG was crucial for diagnosis and subsequently to recommend suitable treatment. However, difficulty in recording this type of crisis with a surface EEG makes correct diagnosis of these patients very difficult, since the epileptogenic focus is deeply situated.

Anticonvulsants↗
PubMed1996

Electro-oculographic recordings reveal reading deficiencies in learning disabled children.

This study was undertaken in order to learn the functional differences in reading tasks between two groups of children: those identified as learning disabled and a group of control children. During the earliest stages of learning to read, children adopt a logographic strategy, in which letter order is ignored and phonologic factors are secondary. The children later move into an alphabetic and then to an orthographic reading stage. Reading strategies can be studied by electro-oculographic (EOG) recordings during text reading. This investigation uses EOG to study text reading time, and number of saccadic and regressive movements, to test if learning disabled children show altered strategies on text reading. Nineteen learning disabled and thirteen control subjects were included in the study. Learning disabled children showed longer text reading time, and greater number of saccadic and regressive eye movements. Electro-oculographic recording is not a test customarily performed on learning disabled children. However, our results concerning the dynamic discriminative reading have shown that it can be a useful tool for the examination of learning disabled children.

Child↗
PubMedDate not supplied

[Electrodiagnosis in disorders of neuromuscular transmission].

INTRODUCTION: Electrophysiological studies are of recognized use in the confirmation of alterations of neuromuscular transmission in further determining their physiopathological characteristics, helping to differentiate them from other conditions with secondary effects on their function. DEVELOPMENT AND CONCLUSIONS: In our study we review the physiopathology of these disorders which compromise the safety factor of the neuromuscular junction, by presynaptic or postsynaptic alterations, and forms the basis of the results of electrophysiological studies. We describe the techniques currently most used: repetitive stimulation and single fibre electromyography complemented by conventional electromyography. Their application and findings in the commonest syndromes are discussed. Finally, their sensitivity, specificity and difficulties are considered.

Electromyography↗
PubMedDate not supplied

[Intraoperative monitoring of nerve roots in spinal surgery].

INTRODUCTION: The use of intraoperative monitoring to determine the functional integrity of the nervous system has grown steadily over the last 15 years. The development of new instrumentation systems in spinal surgery and a greater incidence of complications have led to the need to introduce new methods of monitoring. AIMS AND DEVELOPMENT: The purpose of this study is to analyse the neurophysiological techniques that are currently available and applied in order to prevent injury to nerve roots and the fibres of the cauda equina, to assess their indications and to determine their limitations, as well as the effects caused by anaesthesia.

Electromyography↗