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Biomedical subjects

M Velasco

Publications and source records attributed to M Velasco.

At least 253 records · Page 14Linked to original sources
PubMed1980

Plasma prolactin increase following electric stimulation of the amygdala in humans.

Plasma levels of PRL, GH, FSH, LH, and TSH were studied at various intervals after electric stimulation of the amygdala, in 5 patients in whom electrodes had been chronically implanted in the course of their evaluation for surgical treatment of uncontrollable, temporal lobe seizures. Electric stimulation, but not sham stimulation, elicited in all cases a significant rise in plasma PRL. Plasma GH rose only in 1 patient and TSH in another. No significant changes in plasma FSH or LH were detected. It is suggested that a fine control mechanism of the hypothalamic hypophyseal final common pathway for the control of PRL secretion, may be mediated either by the ventral amygdalohypothalamic pathway or via the stria terminalis.

Adolescent↗
PubMed1980

Transsphenoidal microsurgery in the treatment of acromegaly and gigantism.

Twenty-five patients with acromegaly and 3 patients with gigantism underwent transsphenoidal microsurgery in an attempt to remove the tumor and preserve normal pituitary function whenever possible. An adenoma was identified and removed in 27 of 28 patients. Evaluation 3--6 months postoperatively revealed a GH level less than 5 ng/ml in 29 patients, 5--10 ng/ml in 4 patients and 11--29 ng/ml in 4 other patients. Dynamics of GH secretion were normal in 11 patients who had normal pituitary function and are considered cured. Two patients with low or undetectable GH levels are also considered cured at the expense of being hypopituitary. Three of 7 patients with normal basal GH levels but abnormal dynamics of GH secretion relapsed within 1 yr. Eleven of the 13 patients considered cured did not have extrasellar extension, while 14 of the 15 patients not cured had extrasellar extension. Five patients who were not cured with surgery received radiation therapy. Three patients were treated with an ergot derivative, Lergotrile mesylate, after surgery and radiation therapy failed to normalize GH levels. Transsphenoidal microsurgery is an optimal form of therapy for patients with acromegaly or gigantism, especially those with no extrasellar extension. Dynamics of GH secretion are very useful in evaluating the completeness of adenoma removal.

Acromegaly↗
PubMed1980

Diagnostic significance of the carcino-embryonal antigen in gynecologic neoplasia.

The carcino-embryonal antigen has been studied in 35 patients affected by malignant gynaecologic neoplasia (cervical, endometrial, vulval) and, for control, in 16 patients affected by small tumors of the genital area. In other 9 patients the day to day variability has been studied. Two determinants, before and after therapy were performed on every patient, and in many cases afterwards. The analysis of the results show the scarce reliability of the episodic C.E.A. determination of the plasma. The use of this parameter in the follow-up of malignant neoplasias gynaecologic can only be reserved in cases with high basic values and in which the therapy reduces the plasmic level significantly.

Carcinoembryonic Antigen↗
PubMed1979

A peculiar rhythmic EEG activity from ventrobasal thalamus during paradoxical sleep in man.

A peculiar 3/sec rhythmic EEG activity (named Vc rhythm) was consistently found at the ventrobasal thalamus (nucleus ventrocaudalis) during paradoxical sleep of patients with implanted electrodes used as an electrophysiological procedure for identification of the thalamic targets for the surgical treatment of tremor and rigidity. The Vc rhythm was formed by high voltage, sharp biphasic positive negative potentials which were absent during wakefulness, rare and isolated during slow wave sleep, increased in number and organized in trains during paradoxical sleep and blocked during arousal. Significant changes in number of Vc waves were found when patients shifted through these wakefulness-sleep states. Integrated EMG multiple unit activity also showed significant changes during these wakefulness-sleep shifts, which were parallel although inverse to those showed by Vc waves. A significant negative correlation (r = -0.7126) between number of Vc waves and EMG units was found. In contrast, Vc waves showed no correlation with other electrophysiological indicators of thalamic excitability (multiple unit activity and early evoked potentials) and sleep (scalp EEG frequency and ocular movements).

Electric Stimulation↗
PubMed1979

Wakefulness-sleep modulation of thalamic multiple unit activity and EEG in man.

Quantitative changes in the number of EEG waves and MUA neuronal spikes of various thalamic nuclear groups were studied during steady and transitional wakefulness-sleep states in a group of patients with implanted electrodes, used as an electrophysiological procedure for the surgical treatment of unilateral tremor and rigidity. Thalamic nuclei included ventroposterolateral (VPL), ventrolateral (VL) and centromedian (CM). Steady states included initial wakefulness (W1), slow wave sleep (SWS) I, II, IV and IIL, paradoxical sleep phasic (PSP) and tonic (PST) and final wakefulness (W2). Transitional states included transition from SWS to PSP (transition) and from sleep to W2 (arousal). (1) There was a significant correlation in EEG and MUA between different thalamic nuclei simultaneously recorded in the same patient during different steady-states. (2) Thalamic MUA significantly decreased from W to SWS, increased from SWS to PS and SWS to W2, while thalamic EEG significantly decreased from W to SWS, increased from SWS to W2 but was not significantly modified from SWS to PS, consecutive steady-state shifts. (3) Thalamic MUA significantly decreased while EEG remained unchanged from PSP to PST consecutive steady-state shifts. (4) Both thalamic MUA and EEG significantly decreased from SWS II to IIL while they were not systematically modified from W1 to W2 indirect steady-state shifts. (5) Thalamic MUA significantly increased 1 sec before transition and arousal while EEG increased 5 sec after arousal and did not change during transition.

Adult↗
PubMed1979

A reticulothalamic system mediating proprioceptive attention and tremor in man.

This report descirbes the electrophysiological characteristics of thalamic and subthalamic targets used to control tremor. In these targets exploratory electrodes recorded one or more of the following events. Electrical stimulation produced enhancement of tremor or other complex motor responses. Somatic evoked potentials (SEPs) induced by proprioceptive stimulation showed only late components, the amplitudes of which changed in various attentive situations. Multiunit activity showed spontaneous 3- to 6-Hz rhythmic bursts. And a lesion produced neglect of contralateral extremities and an ipsilateral decrease of scalp-recorded SEP late components. In contrast, in the areas located immediately posterior and dorsal, electrical stimulation produced contralateral paresthesias. Early components of SEPs could be recorded, as were rhythmic bursts of multiunit activity after the occurrence of peripheral tremor. Lesions produced sensory deficits in the contralateral extremities and ipsilateral blocking of all components of scalp SEPs. The latter areas are identified as the lemniscal system, but the former seem to be extralemniscal. Their electrophysiological characteristics suggest that they are probably involved in the process of selective attention and motor control.

Attention↗
PubMed1978

Effect of propranolol on sympathetic nervous activity in hydrallazine-treated hypertensive patients.

1 The effect of propranolol was examined on a) blood pressure and heart rate responses due to i.v. hydrallazine b) modification of these cardiovascular parameters during cold pressor test c) urinary catecholamine excretion rate. 2 Intravenous hydrallazine reduced significantly mean blood pressure by 15.2 mm Hg and increased heart rate by 24.9 beats/min. Propranolol reduced significantly mean blood pressure by 19.0 mm Hg and heart rate by 14.1 beats/min. Hydrallazine plus propranolol caused a significant reduction of mean blood pressure (by 37.7 mm Hg) but this was not accompanied by a significant fall in heart rate (by 3.3 beats/min). 3 During the control period, cold pressor test increased mean blood pressure by 16.0 mm Hg. Heart rate was increased by 12.5 beats/min in four patients. However, there was a reduction in heart rate (5.5 beats/min) in two other patients. During the propranolol period, cold pressor test-induced increase of mean blood pressure was not reduced but propranolol blocked the increase of heart rate. 4 Urinary catecholamine excretion rate was increased during hydrallazine administration. This excretion was not modified by propranolol.

Adult↗