Search PubMed⌕ Search

Biomedical subjects

F Velasco

Publications and source records attributed to F Velasco.

At least 127 records · Page 7Linked to original sources
PubMed1982

Functional activities and concentrations of plasmin inhibitors in normal subjects and D.I.C. patients.

Alpha-2-macroglobulin and fast antiplasmin, the main inhibitors of the fibrinolytic system, and the presence of plasmin-antiplasmin complex (P-AP) were studied in 15 DIC patients and in 20 healthy individuals. There was a lack of correlation between immunological and chromogenic substrates alpha-2 antiplasmin levels when P-AP complex were found in DIC patients (in 6/15 cases). The levels of alpha-2-macroglobulin were within the normal range in most of these patients, confirm the secondary role of this inhibitor in fibrinolysis.

Adolescent↗
PubMed1982

Subcortical correlates of the auditory brain stem potentials in man: bipolar EEG and multiple unit activity and electrical stimulation.

Bipolar EEG and multiple unit activity (MUA) responses related to the vertex auditory brain stem potentials (ABSP) were studied in different subcortical loci in parkinsonian and epileptic patients with implanted electrodes used as an electrophysiological procedure for surgical treatment. In addition, the subjective responses of patients to the electrical stimulation of these subcortical loci were studied for their possible auditory sensations. (1) Two types of bipolar EEG responses to monoaural stimulation were recorded from a limited number of subcortical loci: type A responses were formed by two consecutive components of opposite polarity peaking at 5.2 and 8.5 msec post-stimulus in 3 different loci contra- and ipsilateral to the stimulated ear: mesencephalic reticular formation (MRF), medial geniculate (MG) and lateral geniculate (LG) nuclei thalami. The polarity of the first component was everted while the second component was inverted between MRF and MG. Type B responses were formed by one component mainly peaking at 15.5 msec post-stimulus with no polarity reversal in either side within the ventral portion of the hippocampus bilaterally (CnA). (2) MUA responses were recorded only within the basal portion of MG bilaterally. Contralateral MUA responses consisted of 3 consecutive activation bursts peaking at 5.5, 7.2 and 9.0 msec post-stimulus and correlated in latency with waves IV-V, VI and VII of ABSP respectively. Ipsilateral MUA responses consisted of two consecutive activation bursts peaking at 14.0 and 16.0 msec post-stimulus and correlating with SN following ABSP. (3) Threshold electrical stimulation of the MG elicited subjective auditory responses referred to the contralateral ear.

Auditory Pathways↗
PubMed1982

Specific and non-specific multiple unit activities during pentylenetetrazol seizures in animals with mesencephalic transections.

A group of cats with brain stem transection at the mesencephalic level was studied during the administration of convulsive doses of pentylenetetrazol in regard to changes in EMG multiple unit activity (MUA), as a method to determine the course of muscular convulsions and their relation with EEG and MUA changes in the motor cortex, pyramidal tract and mesencephalic and pontine reticular formations. PTZ induced significant increase in the duration of EMG tonic convulsions, lasting 3-100 times longer than the entire tonic-clonic seizure seen in intact animals after similar doses of PTZ and not accompanied by EEG or pyramidal tract "seizures", but by an equally long-lasting increase in MUA of mesencephalic and pontine reticular formations. Comparing present results with those seen in intact, "encéphale isolé" and "pretrigeminal" preparations, it is concluded that the mesencephalon is important for both: activating tonic phase of the convulsions and the EEG changes seen in PTZ-induced seizures. It also suggests that termination of seizures is due to inhibitory influences of supramesencephalic structures.

Animals↗
PubMed1982

Subcortical correlates of the auditory brainstem potentials in the monkey: referential responses.

Referential responses correlated with the vertex auditory brain-stem potentials (ABSP) were recorded from different brainstem and diencephalic structures of large monkeys under barbiturate anesthesia. Polarity, latency, and amplitude of various response components were determined from structures located 2 mm apart along five different vertical trajectories aiming at the trapezoid body (TB), superior olivary complex (SOC), mesencephalic reticular formation (MRF), medial geniculate nucleus thalami (MG), and inferior colliculus (IC). Latency correlations, amplitude differences, voltage profiles, current-source-density-distribution, and current flows of the various response components were subsequently calculated. Subcortical referential responses were formed by seven initial fast positive components (I, II, A, B, C, D and E) and one late slow negative component (F) correlated to waves I to VII and SP3 of the vertex ABSP respectively. Positive components C and D' also correlated to SP1 and SN1 of ABSP respectively. Amplitude of component B at contralateral SOC and C, D' and F at contralateral MRF was significantly larger than those of other subcortical responses and vertex ABSP. A single component of the subcortical referential responses accompanied changes in voltage, CSD, and current flows of various brainstem structures. However, considering only major changes in these parameters, component B accompanied a voltage positive and a CSD positive-negative peak and an ascending current flow at the SOC; component C accompanied similar changes at MRF, and components D' and F accompanied voltage negative and CSD negative-positive-negative peaks and ascending and descending current flows at MRF. In contrast, no systematic changes in voltage, CSD and current flows accompanied components I, II, A, D and E.

Animals↗
PubMed1982

Effect of dextro-amphetamine on reticulo-preoptic interactions in "encéphale isolé" cats.

Intravenous administration of a single dose of dextro-amphetamine (1 mg/kg) in the "encéphale isolé" cat significantly increased amplitude of the P50 and N110 components of the preoptic potential evoked by the stimulation of the mesencephalic reticular formation and decreased all components of the mesencephalic reticular formation potential evoked by preoptic stimulation. Concomitantly, a state of increased and persistent arousal response was found. These findings support the idea that during wakefulness there is a reticular facilitation and a preoptic inhibition.

Animals↗
PubMed1981

[Ventricular septal defect: Prognosis of spontaneous closure (author's transl)].

In a series of 150 cases of isolated ventricular septal defect (VSD), the authors have found 25 cases (16%) of spontaneous closure over an average period of observation of 20 months. The closure was observed in 32% of the cases before 6 months and in 60% before 12 months, with a range between 1 month and 8 years. The number of out patient with was 7 per case on average. A large group of parameters was taken into account in every case; from some of them, indicators of prognosis of closure were obtained, among them: early appearance of the murmur, descending shape, muscular character of the VSD, absence of symptoms and diastolic rumble, presence of ejection clic and normality in ECG and XRay.

Age Factors↗
PubMed1980

Alumina cream-induced focal motor epilepsy in cats. IV. Thickness and cellularity of layers in the perilesional motor cortex.

Thickness and cellularity of motor cortical layers adjacent to epileptogenic lesions produced by administration of alumina cream (AC) were measured in the brains of 18 cats that were at latent, convulsive, and remissive stages of an experimental model of epilepsy. Sham-operated animals were used as controls. Brains were fixed by perfusion and embedded in paraffin. Sections of motor cortex adjacent to the AC deposit were obtained at constant thickness to measure thickness and cellularity in each cortical layer. A statistically significant reduction in thickness and cellularity was detected in layers 2, 4, and 6, whereas reduction in these aspects was not significant in layers 3 and 5 in the initial stages of the model (latent and convulsive). It is suggested that AC may exert a cytotoxic effect on inhibitory neurons located at layers 2 and 4, to determine an imbalance of intracortical excitability.

Aluminum Hydroxide↗