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Biomedical subjects

G Gandolfo

Publications and source records attributed to G Gandolfo.

At least 37 records · Page 2Linked to original sources
PubMed1989

Ca2+ channel blockers prevent seizures induced by a class of K+ channel inhibitors.

Intracerebroventricular injection into rats of mast-cell degranulating peptide (MCD), dendrotoxin I (DTXI) and 4-aminopyridine (4-AP), three blockers of a subclass of K+ channels, elicited epileptiform wave bursts and convulsions. Three different types of L-type Ca2+ channel inhibitors (+)PN 200-110, a 1,4-dihydropyridine, (-)D888, a phenylalkylamine, and fluspirilene, a diphenylbutylpiperidine, were potent blockers of the convulsant-induced hyperexcitatory effects when they were administered preventively. D-AP5, a N-methyl-D-aspartate antagonist, was active on the 4-AP-induced seizures but was without effect on the MCD- and dendrotoxin-induced seizures.

4-Aminopyridine↗
PubMed1989

Hippocampal theta activity in the acute precollicular rat.

In eleven acute precollicular rats, cortical and hippocampal EEG activity was recorded. Hippocampal theta activity of low frequency (mean 4.5 c/sec) was found in nine rats and in four occupied above 50% of the recording time. In contrast, in the cortex the synchronized EEG activity dominated. The electrical stimulation of the posterior hypothalamus induced the theta rhythm, or increased its frequency. The large amounts of theta activity in some rats suggests that the forebrain theta pacemakers, partly modulated by the posterior hypothalamus, are released from brain stem inhibitory influences.

Animals↗
PubMed1988

Fetal serotoninergic transplants in the fourth ventricle of adult rodents reverse sleep disturbances induced by neonatal administration of 5,7-dihydroxytryptamine.

Rats received a neonatal (at 4 days of age) intracisternal injection of 5,7-dihydroxytryptamine which eliminates serotonin (5-HT) throughout adulthood. Sleep recordings, performed on these rats at adult age, demonstrated significant decreases in paradoxical sleep. Dissociated fetal 5-HT cell suspensions transplanted in the IVth ventricle of these rats restored paradoxical sleep. However, fetal neuronal noradrenergic or cholinergic transplants did not restore paradoxical sleep. These results suggest that paradoxical sleep is directly or indirectly mediated through serotoninergic mechanisms.

5,7-Dihydroxytryptamine↗
PubMed1988

Automatic sleep-wake scoring in the rat on microcomputer APPLE II.

An automatic scoring system in real time of sleep-wake behavior in the rat was elaborated on microcomputer APPLE II. Four electrophysiological recording channels were used to distinguish seven behavioral states. Because the rat shows behavioral stages which are short-lasting, the analysis is performed second by second. It is based on the detection of the signal energy in specific frequency bands. The percentage of time passed in each stage is computed every 15 min, 1 h, 6 h and 24 h, the analysis extending during several days without interruption. The data are also printed out in a listing in real time and histograms in batch mode. Because of the interindividual differences, a calibration is needed. It is performed with a program in batch mode which allows an adjustment of parameters of determination from given specific digitized sequence in each rat. The accuracy of the automatic method was tested by the C contingency test, the theoretical maximal level being at 0.93: the intra- and inter-researchers contingency was 0.89, that between researchers and the computer was 0.85.

Animals↗
PubMed1988

Incidence and prognostic significance of autoantibodies against erythrocytes and platelets in chronic lymphocytic leukemia (CLL).

Antiglobulin Test (AT), and Dixon Tests (DT) have been studied in 100 patients with CLL. Thirty-five patients were Rai stage 0 and I, 19 patients stage 2, 13 patients stage 3 and 33 patients stage 4. Twelve patients showed a Red Blood Cells Autoantibodies (RBCAb) positivity; a positivity (direct, indirect, or both) of DT was present in 74% of patients. The presence of autoantibodies against erythrocytes and platelets did not influence survival curves, but anemia and thrombocytopenia are risk factors for survival, independently of the presence of an autoimmune disorder. Nine patients RBCAb positive and DT positive showed the worst survival curve, five out of these were anemic and one thrombocytopenic and anemic.

Aged↗
PubMed1987

The brain response to the bee venom peptide MCD. Activation and desensitization of a hippocampal target.

The mast cell-degranulating peptide (MCD) isolated from bee venom has been found previously to have receptor sites in rat brain. Behavioral and electrocorticographic responses following intracerebroventricular injections of various doses of MCD have been analyzed. MCD produced a quasi-permanent hippocampal theta rhythm in the motionless animal alternating with epileptiform spike waves and paroxystic seizures. At a dose of 70 pmol seizures occurred for half of the treated rats. At a dose of 100 pmol generalized paroxystic crises were observed for all the rats. These effects were not antagonized by naloxone, morphine, diazepam and progabide. Rats recovered 24 h after a 100 pmol injection of MCD. A second ipsilateral injection to these rats showed the occurrence of a desensitization phenomenon. Desensitization was not observed when the second injection was contralateral. These physiological responses were studied in relation with a biochemical approach on membrane sites of action of MCD using [125I]MCD and their behavior in the desensitization process. The target of [125I]MCD is the ipsilateral hippocampus. Recovery from MCD effects was not due to MCD degradation. Desensitization was not due to down-regulation of the MCD receptor level.

Animals↗
PubMed1986

Statistical argument for a presynaptic origin of the second positive component of somesthetic primary cortex evoked potential elicited by central afferent stimulation.

The positive components 1 and 2 of the averaged field response induced in the somesthetic S1 cortex by submaximal stimulation of cortical radiation and supramaximal stimulation of lemniscus medialis showed non-existent amplitude variability whereas the dispersion was significant for components 3, 4 and 5. The same stimulus delivered at a short intershock interval only induced waves 1 and 2 without any amplitude variability, the three following ones being under complete refractoriness. These results suggest a presynaptic origin of component 2.

Animals↗
PubMed1986

[Neonatal administration of 5,7-dihydroxytryptamine induces in the adult rat a decrease in paradoxical sleep restored by an intracisternal injection of fetal raphe cells].

By a method of automatic on-line scoring of sleep-waking stages in the rat, a significant decrease of the mean circadian level of paradoxical sleep and a significant increase of light slow sleep were shown in adult animals after neonatal disruption of serotoninergic system by intracisternal injection of 100 micrograms of 5.7-dihydroxytryptamine, when compared to an aged matched sham group. The level of paradoxical sleep was restored in the neurotoxin-treated rats by an intracisternal injection of a suspension of foetal raphe neurons.

5,7-Dihydroxytryptamine↗
PubMed1986

A massive but short lasting forebrain deafferentation during sleep in the rat and cat.

The rat and cat show just prior and sometimes after paradoxical sleep a short-lasting behavioral stage characterized by: i) frontal cortex high amplitude spindle bursts and low frequency theta activity in the dorsal hippocampus, and ii) the lowest ventrobasal complex transmission level of all sleep-waking stages. The duration of this "intermediate" stage is increased at the expense of paradoxical sleep by low doses of barbiturate. The intercollicular "cerveau isolé" preparation shows for hours the electrophysiological patterns of the intermediate stage. It is concluded that the intermediate stage of sleep corresponds to a forebrain massive deafferentation process leading to a functional disconnecting from the brainstem. For the survival of the species it is understandable that this behavioral stage is necessarily short lasting.

Animals↗
PubMed1985

Cerveau isolé and pretrigeminal rat preparations.

Cortical and hippocampal EEG activity was analysed in cerveau isolé and and pretrigeminal rats. In the acute stage, waking EEG patterns were absent in the cerveau isolé, whereas sleep EGG patterns were absent in the preparations. However, already on the second day the EEG waking sleep cycle recovered in the majority of rats. Paradoxically, stimuli directed to the caudal part of the preparations evoked stronger cortical and hippocampal EEG arousal than olfactory and visual stimuli. The rats exhibited some locomotor and grooming behaviour and could be fed orally. It is concluded that the activity of the isolated cerebrum of the rat is similar to that of cat preparations, but that functions of the caudal neuraxis are superior in rats.

Animals↗
PubMed1985

Study of sleep spindles in the rat: a new improvement.

The two kinds of sleep spindles, previously described in the rat, were studied in intact animals, cerveau isole preparations and unilaterally neodecorticated rats. The anterior (frontal) spindles reach their maximum during deep slow sleep, when accompanied by theta activity, during the so-called intermediate stage which occurs just before and after paradoxical sleep. This stage is extended by low doses of barbiturate and similar patterns are induced by an intercollicular transection. The anterior spindles are suppressed by unilateral nedecortication and become abortive on contralateral hemisphere. The posterior ones, larger when recorded in the dorsal hippocampus than an the occipital cortex precede the appearance of the theta activity of intermediate stage. They are absent when the theta rhythm is present, during the long-continued intermediate stage under barbiturate ad in the cerveau isole preparation; but an unilateral neodecortication does not prevent the occurrence of posterior spindles on the white matter. Thus, during deep slow sleep, the rat shows both frontal cortex spindles, fully spread out during intermediate stage, and posterior spindles, probably originating from structures implied in the theta genesis and heralding the occurrence of this rhythmic slow activity.

Animals↗
PubMed1984

Cerveau isolé and pretrigeminal rats.

Cortical and hippocampal EEG activity was analysed in 14 cerveau isole and 8 pretrigerninal rats. In the acute stage, waking EEG patterns were absent in the cerveau isole, whereas sleep EEG patterns were absent in the pretrigeminal preparations. However, already on the second day the EEG waking-sleep cycle recovered in the majority of rats. Paradoxically, stimuli directed to the caudal part of preparations evoked stronger cortical and hippocampal EEG arousal than olfactory and visual stimuli. The behavior of the caudal part was observed in 25 preparations. Although in abortive form, the rats did show some locomotor and grooming behavior, and could be fed orally. The peripheral events of paradoxical sleep appeared only on the fourth or fifth day of survival of the cerveau isole rats. It is concluded that the activity of the isolated cerebrum of the rat is similar to that of cat preparations, but that functions of the caudal neuraxis are superior in rats.

Animals↗
PubMed1984

Intermediate stage of sleep in the cat.

Intermediate stage of sleep, previously described in the rat, was studied in the cat. The intermediate stage was a short-lasting episode, represented in the EEG activity by cortical spindles, which was accompanied by theta activity in the hippocampus. The cortical EEG spindles appeared simultaneously with hippocampal theta or on its background. Sometimes, geniculo-occipital waves were recorded during this stage. Such an episode of a few such episodes in sequence occurred frequently just before the paradoxical sleep and occasionally just after it. The amplitude of the positive fourth component of the somesthetic evoked potential induced in the S1 cortex by stimulation of the ventrobasal complex, was lower during the intermediate stage than during the other stages of the sleep-waking cycle. The EEG pattern of the intermediate stage was periodically observed under Nembutal anesthesia at the expense of paradoxical sleep and in acute cerveau isolé preparation. The results suggest that activatory ascending influences from the brainstem, which modulate waking processes, gradually decrease during slow sleep and are the lowest during the intermediate stage, when the influences for paradoxical sleep are still negligible.

Animals↗
PubMed1982

Transmission in the ventrobasal complex of thalamus during rapid sleep and wakefulness in the homolaterally neodecorticated rat.

The thalamic input was assessed from the amplitude of field evoked potential induced antidromically in the lemniscus medialis by ventrobasal complex stimulation. In the control rats, the amplitude of the antidromic response was greater during waking with theta activity in the dorsal hippocampus, i.e., in the attentive and/or psychomotor active animal, than during waking without theta rhythm. During rapid sleep, the antidromic response also transiently increased in amplitude during the bursts of rapid eye movements. After homolateral neodecortication, the difference between the two waking states disappeared in terms of the magnitude of the evoked response, while during rapid sleep the enhanced response during periods of eye movement bursts was still present. The thalamic output was studied by measuring the amplitude of postsynaptic field evoked potential induced by lemniscal stimulation. In control rats, the responsiveness level was higher during waking without theta as related to waking with theta and during rapid sleep as compared to rapid sleep periods with eye movement bursts. Homolateral decortication did not affect the characteristic modulations of thalamic output both during waking and rapid sleep. Results show that ventrobasal complex transmission is modulated: (i) during waking with theta by both corticofugal presynaptic and extracortical postsynaptic processes, (ii) during eye movement bursts of rapid sleep by an extracortical presynaptic control.

Afferent Pathways↗
PubMed1981

Hippocampal theta activity in the acute cerveau isolé cat.

In three cerveau isole cats, cortical and hippocampal EEG activity were recorded. In the cortical records, spindles alternated with low-voltage activity, whereas theta activity dominated in the hippocampus. The amount and frequency of theta were similar to those described previously for the pretrigeminal cat. In confirmation of previous results on rats, although cortical EEG activity differs in cerveau isole cat and pretrigeminal cat, both preparations show domination of theta activity in the hippocampus. It is concluded that the mesencephalic transection eliminates inhibitory effects from the lower brainstem on generators of the theta rhythm.

Animals↗