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Biomedical subjects

M Velasco

Publications and source records attributed to M Velasco.

At least 199 records · Page 11Linked to original sources
PubMed1984

Paroxysmal discharges during paradoxical sleep anticipating the occurrence of focal motor seizures in cats.

Sleep recordings were made some days before the occurrence of focal motor seizures in cats injected with alumina cream in the motor cortex. The wakefulness EEG was completely normal. Slow-wave sleep showed spike-spindles and occasional isolated spikes. During paradoxical sleep, abortive seizures appeared. They were only electrographic and never produced arousal of the animals. The precipitating role of phasic paradoxical sleep on focal motor seizures is proposed.

Animals↗
PubMed1984

Effect of fentanyl and naloxone on the P300 auditory potential.

The effect of fentanyl (opioid agonist) and naloxone (morphine antagonist) on the amplitude, area and latency of the P300 auditory potential was studied in patients undergoing minor surgical procedures. Fentanyl (5.0 micrograms/kg), naloxone (3.0 micrograms/kg) and isotonic saline (for control) were injected intravenously through a catheter just before surgery, and following a single-blind procedure and three different pharmacological paradigms with three consecutive conditions each: (1) initial baseline (C), saline (S) and late baseline (C'); (2) C, fentanyl (F) and C'; (3) C, naloxone (N) and C'. Fentanyl significantly reduced the amplitude and area with no changes in the latency of small (S) and large (L) P300 potentials. Concomitantly, fentanyl increased the number of omitted counts of the target tones of the "odd ball" P300 test and the spatial threshold of the two point discrimination test in patients with small and large P300 potentials. Naloxone significantly increased the amplitude and area and decreased the latency of the small P300 potential and decreased the amplitude and area with no changes in latency of the large P300 potentials. Concomitantly, naloxone decreased the number of omitted counts of the patients with small but not large P300 potentials and decreased the spatial threshold in patients with both small and large P300 potentials. Neither fentanyl nor naloxone produced systematic changes in the evaluation of pain and hearing of patients with small and large P300 potentials. Although dramatic changes in pulse, blood pressure, respiration and EEG were found in some cases immediately after the administration of fentanyl and naloxone, these changes were not consistent and were not present at the time other tests were performed.

Adult↗
PubMed1984

Effect of fentanyl and naloxone on human somatic and auditory-evoked potential components.

The effect of fentanyl (a morphine agonist) and naloxone (a morphine antagonist) on early and late components of somatic (SEP)- and auditory (AEP)-evoked potentials was studied in patients undergoing minor surgical procedures, in which these compounds were used in producing and regulating a state of neuroleptanalgesia. Fentanyl (2.5, 5.0 and 10.0 micrograms/kg), naloxone (1.5 and 3.0 micrograms/kg) and isotonic saline (for comparative purposes) were injected just before surgery, intravenously through a catheter and following a single blind procedure and three different pharmacological paradigms with four consecutive conditions each: (1) Initial baseline (C), first saline (S), second saline (S') and late baseline (C'). (2) C, First fentanyl (F), second naloxone (N') and C. (3) C, First naloxone (N), second fentanyl (F') and C'. Special care was taken in controlling the constancy of the muscular and cochlear receptor activation concomitant to somatic-evoked potentials and auditory-evoked potentials, determined by the amplitude of the muscular response at the tenar muscles (MP) and component I of the brain stem potentials ( ABSP ). Evaluation by the patients pain, topognoses and hearing and other somatic and autonomic indicators of the level of the analgesic response were also controlled. Fentanyl significantly reduced, while naloxone increased, the amplitude of late components P150 of somatic-evoked potentials and auditory-evoked potentials. Concomitantly, fentanyl increased, while naloxone decreased, the spatial threshold (two point discrimination test) at finger tip and arm. These effects were observed in patients taking various doses, although they were more consistent with larger doses of these compounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Alumina cream-induced focal motor epilepsy in cats. Part 5. Excision and transplant of the epileptogenic granuloma.

The role of alumina cream (AC) epileptic granulomas in producing clinical convulsions and EEG spikes was evaluated by excising and transplanting such granulomas from donors to recipient cats. In donors, granulomas were produced by single microinjections of AC into the right motor cortex and were subsequently excised during latent premature (P), mature (M), convulsive, and remission stages. The excised granulomas from donors were homogenized and injected into the homologous cortices of the recipient cats. The epileptogenic effect of the AC granuloma transplant in the recipients and the antiepileptogenic effect of the AC granuloma excision in the donors were evaluated by the presence or absence of clinical convulsions and the maximal EEG spike density at the right motor cortex (MSD) after lesion excision and transplant. In addition, a correlation between MSD (spikes/10 min) of donors and recipients and the aluminum content (microgram/ml) in granuloma and perilesional cortex of control epileptic cats (neither excised nor transplanted) was established during latent P, M, convulsive, and remission stages. The epileptogenic effect of AC granulomas transplanted into recipients was significantly larger when they were excised from donors in latent P and M than in convulsive, and in convulsive than in remission. The antiepileptogenic effect of AC granuloma excision in donors was significantly larger in latent P than in latent M and convulsive, and in convulsive than in remission. The aluminum content of AC granuloma and perilesional and contralateral cortices in controls was significantly larger in latent P and M than in convulsive and in convulsive than in remission.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1984

Subcortical correlates of the auditory brain stem potentials in the monkey: bipolar EEG and multiple unit activity responses.

Bipolar EEG and multiple unit activity (MUA) responses correlated to the vertex auditory brain stem potentials (ABSP) were recorded in different brain stem and diencephalic primary auditory pathways and other anatomically related structures of large monkeys under barbiturate anesthesia. Bipolar EEG responses were recorded bilaterally to monaural stimulation and were formed by 3 or more of 6 consecutive components labeled A, B, C, D, E and F (peak latencies of 3.8, 4.2, 4.6, 5.0, 7.8 and 11.8 msec) correlated in latency with waves III, IV, V, VI, VII and SP3 of the ABSP, respectively. Component B was prominent and showed clearcut reverse polarity at the trapezoid body (TB) and superior olivary complex (SOC), while components C and F inverted and everted polarity at the mesencephalic reticular formation (MRF) and medial geniculate nucleus thalami (MG). Subcortical MUA peaks A, B, C, D and E time locked to the stimulus presentation correlated in latency to those of the bipolar EEG responses. In addition, a significant correlation was found between percentage amplitude of the subcortical EEG response components and MUA peaks in different structures contra- (r = 0.847) and ipsilateral (r = 0.973) to the stimulated ear. Although a single wave of the vertex ABSP correlated in latency with more than one response component in different subcortical loci, amplitude of component A was significantly larger (P less than or equal to 0.02) at TB ipsilateral, B at TB and SOC bilateral, and C and F at MRF, and D and E at MG contralateral to the stimulated ear.

Acoustic Stimulation↗
PubMed1984

Plasma prolactin in women with mastodynia.

Plasma prolactin was measured by radioimmunoassay during the luteal phase in 22 patients affected by moderate or severe mastodynia and results were compared to those of 43 control subjects. No consistent changes were seen during the course of the luteal phase in either group. No significant differences were noted between the prolactin levels of the two groups. No association was found between moderate or severe mastodynia and variations of plasma prolactin levels.

Adult↗
PubMed1983

Alumina cream-induced focal motor epilepsy in cats. IV. Peduncular and midline tegmental lesions.

The effect of peduncular and midline tegmental lesions on EEG-EMG patterns of type B and C alumina cream-induced focal motor seizures was studied on cats with chronically implanted electrodes and cannula lesion systems. EEG patterns included number, amplitude and contralateral propagation of type B spikes and occurrence and duration of type C tonic-clonic discharges. EMG patterns included phasic multiple unit activity (EMG MUA) time locked to the onset of type B EEG spikes and time locked to the onset (contradversive OTCD) and end (clonic ETCD) of type C tonic-clonic EEG paroxysmal discharges. (1) Lesions of the middle third of the cerebral peduncle, ipsilateral to the cortical epileptogenic focus, blocked type B muscular convulsions and significantly decreased phasic EMG MUA at contralateral face, neck and limbs. (2) Bilateral peduncular lesions blocked clonic type C muscular convulsions and significantly decreased phasic clonic ETCD EMG MUA at the same body regions. (3) Midline tegmental lesions blocked phasic type C muscular convulsions and significantly decreased phasic contradversive OTCD EMG MUA at neck muscles. (4) Bilateral peduncular lesions significantly increased and midline tegmental lesions significantly decreased (below the previous interictal) contradversive OTCD EMG MUA. (5) Neither peduncular nor midline tegmental lesions significantly changed EEG patterns of type B and C seizures.

Aluminum Oxide↗
PubMed1983

Push-pull perfusion of pentylenetetrazol in the brain stem of 'encéphale isolé' cats.

Nine 'encéphale isolé' cats had 'push-pull' perfusions of pentylenetetrazol (PTZ) in various loci of the brain stem, while the EEG from the right and left motor cortices, EMG from neck muscles, ocular movements and clinical changes were recorded. Perfusions in the rostral MRF induced bilateral rhythmic paroxysmal EEG discharges and myoclonic twitching of neck and head, more prominent in the muscles contralateral to the perfused side. PTZ in the caudal MRF induced tonic-clonic paroxysmal EEG discharges and EMG seizures, similar to those seen when PTZ is injected systemically. Perfusion in the PRF induced EEG spindle bursts, muscular hypotonia and myosis. When perfusion in the MRF inducing rhythmic paroxysmal EEG discharges and myoclonic twitching was followed by perfusion in the PRF, the EEG discharges were not modified, but the myoclonic movements were abolished. Perfusions outside the MRF and PRF did not produce obvious changes other than tonic gaze deviation to the contralateral side or nystagmus. The results suggest that PTZ has a differential effect in various structures of the CNS, producing primary generalized convulsive seizures when acting directly on the MRF.

Animals↗
PubMed1983

Effect of sagittal transections of the brain stem tegmentum on alumina cream-induced focal motor seizures in cats.

The effect of extensive and circumscribed sagittal transections of the brain stem tegmentum on types B (epilepsia partialis continua) and C (contradversive tonic-clonic seizures) alumina cream-induced focal motor seizures in cats was investigated. The neurological abnormalities of cats with transections and differences in the EEG-EMG patterns of types B and C seizures between operated and intact animals were statistically analyzed. Animals with either extensive or superior central nucleus transections showed bilateral neglect and internuclear palsy syndromes, no tonic type C seizures (contradversion), and a significant decrease in electromyogram multiple-unit activity (EMG MUA) from 0 to 10 s or more after the onset of EEG paroxysmal tonic-clonic discharges. Animals with rostral transections showed a unilateral neglect and internuclear palsy or ataxic syndromes with a concomitant partial reduction of contradversive seizures and a significant decrease in EMG MUA from 0 to 5 s or less after the onset of EEG tonic-clonic discharges; those with dorsal and caudal transections showed a transient neglect and insomniac syndromes with no differences in contradversion and EMG MUA at the onset of EEG tonic-clonic discharges in relation to intacts. Experimental and intact animals showed neither differences in types C and B EEG patterns nor in EMG MUA at the end of type C EEG tonic-clonic discharges and type B EEG spikes. These results support the idea that tonic and clonic muscular seizures are due to epileptic impulses originating in the cerebral cortex and mediated at the level of the brain stem by different pathways.

Aluminum Oxide↗
PubMed1983

Cardiovascular hemodynamic interactions between clonidine and minoxidil in hypertensive patients.

The systemic, cardiovascular hemodynamic and biochemical interactions between clonidine and minoxidil were studied in ten patients with refractory and/or accelerated hypertension. Clonidine in oral doses of 150 to 900 micrograms/day decreased mean blood pressure (MAP) 18.6 mm Hg (p less than 0.01), average heart rate (HR) 16.4 bpm (p less than 0.01), limb blood flow 1.63 ml/100 g min (p less than 0.05), plasma renin activity (PRA) 1.13 ng/ml/hr (p less than 0.025), and urinary noradrenaline excretion rate 16.45 micrograms/24hr (p less than 0.05). Clonidine increased the preejection period index (PEPI) 12.4 msec ( p less than 0.001), but did not alter cardiac index (CI), total peripheral resistance index (TPRI), limb vascular resistance nor dopamine beta-hydroxylase activity. When minoxidil in oral doses of 5 to 22.5 mg was added, a further decrease in MAP of 24.2 mm Hg (p less than 0.01) was observed; PEPI decreased 20.6 msec (p less than 0.01), limb blood flow decreased 13.2 mm Hg/min 100 g/ml (p less than 0.05), and total peripheral resistance index decreased 13.3 mm Hg/min m2/L (p less than 0.05). Minoxidil increased average heart rate 8.2 bpm (p less than 0.05), PRA 1.68 ng/ml/hr (p less than 0.05) and urinary noradrenaline excretion rate 5.0 micrograms/24 hr (p less than 0.01). Limb blood flow, cardiac index and dopamine beta hydroxylase activity were not significantly altered by minoxidil. Neither clonidine nor minoxidil affected cardiovascular responses to treadmill exercise. We concluded that clonidine is a useful alternative agent to block a minoxidil-induced increase in sympathetic nervous activity.

Adult↗
PubMed1983

A comparative study on the effects of pindolol and propranolol on systemic and cardiac haemodynamics in hypertensive patients.

Eight out-patients with essential hypertension participated in a comparative, placebo-controlled study with a cross-over design. Pindolol and propranolol were administered orally in doses of 20.0 +/- 3.13 mg/d (mean +/- SEM) and 125.0 +/- 19.17 mg/d respectively. Pindolol reduced mean blood pressure by 11.9 mmHg; pre-ejection period index by 8.1 msec; total peripheral resistance by 3.1 mmHg min/L; and limb vascular resistance by 3.28 mmHg min 100 g/ml. Heart rate, cardiac output, plasma renin activity and urinary norepinephrine excretion rate were not altered by pindolol. Propranolol reduced mean blood pressure by 14.0 mmHg; heart rate by 9.1 beats/min; cardiac output by 0.57 L/min; limb blood flow by 1.06 ml/100 g.min; and plasma renin activity by 1.44 ng/ml/h; and increased pre-ejection period index by 8.7 msec. Total peripheral resistance, limb vascular resistance and urinary norepinephrine excretion rate were not altered by propranolol. It was concluded that: (1) the drugs, pindolol and propranolol, are equally effective as antihypertensive agents; (2) heart function and plasma renin activity are decreased by propranolol and unaltered by pindolol; (3) total peripheral resistance is decreased by pindolol and unaltered by propranolol; and (4) these findings may be explained by the intrinsic sympathomimetic activity exhibited by pindolol only.

Adult↗