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Biomedical subjects

F Laffont

Publications and source records attributed to F Laffont.

At least 37 records · Page 2Linked to original sources
PubMed1985

[Spinal and cortical SEP's in healthy subjects and paraplegics].

SEPs are evoked by electrical stimulation of tibial nerve in the fossa poplitea. Surface electrodes, located in S1, L4, L2, T12 with a reference in T6, can record lumbar evoked potentials and calculate a peripheral sensitive velocity. Bipolar leads between electrodes located in T12, T9, T6, T3 and C7 record medullary potential and calculate a medullary transit velocity. The cortical potential is monitored between C'z and a non-cephalic reference. 25 controls and 10 paraplegic patients are studied. In controls, sensitive peripheral velocity is 59 m/sec. The lumbar potential is composed of two negative waves, respectively due to the activation of sensitive roots and to the medullary potential. The medullary transit velocity, measured by the increase of the latency of the culmination of this negative wave along the spine, is 60 m/sec. The cortical potential is composed of two stable waves P30 N38 which are observed in every control; these waves are followed by a succession of positive and negative waves. In the 10 paraplegic patients, complete anesthesia observed in 5 cases is associated with an absence of cortical potential, and the hypoesthesia observed in 5 cases is associated with a cortical potential with a reduced amplitude (2 cases) or an increased latency (3 cases). In these last 3 cases, the medullary potential allows to specify the location of slowing of the transit velocity.

Adult↗
PubMed1984

Sleep disturbances in a case of brain-stem lesions; pharmacological study.

A pharmacological study was carried out of a case of severe insomnia following brain-stem lesions; several polygraphic controls were used. Initially total duration of sleep was brief (less than 4 h) with a high REM/NREM ratio and a short paradoxical sleep (PS) latency. In addition, periodic breathing and tremor were observed. Slow injection of delta-sleep-inducing peptide (DSIP) improved sleep both quantitatively and qualitatively, although PS latency remained short. These effects were reversible. The effects of 5-HTP + benzerazide, of L-DOPA + benzerazide (Modopar) and of clonazepam (Rivotril) were compared.

Brain Stem↗
PubMed1984

[Frontal evoked potentials and sensitivity to methylphenidate. Individual differences].

Auditory evoked potentials (AEPs) were recorded from 2 sites (Cz and Fz) on 17 subjects while awake. Five sound intensities were used (40-50-60-70-80 dB). Regression slopes relating AEP amplitude (N1-P2 component) to stimulus intensity were used to describe augmentation or reduction (A/R) of amplitude with increasing intensity. The individual differences thereby obtained have been related with the individual responsiveness to methylphenidate (MPD) measured by the modifications of polygraphic sleep parameters after absorption of this substance. The sleep parameters were recorded under 3 conditions: N1, night of habituation; N2, reference night (placebo); N3, night after 20 mg of methylphenidate (MPD); nights 2 and 3 consisted of a double blind cross-over. For the placebo condition, the lower the A/R slope while awake (and particularly the Fz slope), the higher the sleep efficiency, with scarcity of nocturnal awakening and precocity of the morning awakening. Individual differences concerning MPD responsiveness measured with sleep parameter modifications are significantly correlated with the frontal A/R slopes: the wakefulness effect of MPD increases as the frontal A/R slope weakens while a paradoxal drowsiness effect is observed at the other extreme (frontal augmenters). Moreover, sleep modifications due to the first night effect show similarities with those due to MPD and are correlated in the same way with frontal A/R slopes.

Adult↗
PubMed1983

Influence of waking and sleep stages on the inter-ictal paroxysmal activity in partial epilepsy with complex seizures.

Twenty-six patients suffering from partial epilepsy with complex seizures underwent polysomnographic recording. Paroxysmal activity (PA) densities in waking and sleep stages were assessed. Total PA densities of one night were found to be an increasing function of the seizure frequency in the previous period. Nineteen patients had more PA during sleep, 5 others in the waking state and the two remaining patients exhibited no differences in PA densities between sleep and waking. Nocturnal seizures were reported by patients showing the sleep PA increase pattern; they also used more anti-convulsants than patients showing the waking PA increase pattern. Differences in PA densities between these two groups were more pronounced in the more desynchronized (waking) and the more synchronized (stages 3 + 4) cortical states. The modulation by slow wave sleep stages was independent of, and superimposed on, the sleep/waking one.

Adolescent↗
PubMed1983

[Paroxysmal nocturnal activity in partial epilepsy in the adult].

Thirty-four adults with partial epilepsy underwent polysomnographic sessions. Three sub-groups of patients were determined by timing their EEG paroxysmal activities (PA) according to the possible increase in PA related to their sleeping or awake state. Twenty-seven had an increase in PA when sleeping, 5 when awake and no significant difference was found in two other patients. Patients who suffered from nocturnal or partial elementary epileptic seizures were those who showed a PA increase when in a sleep state. These patients had a lower PA density during a waking state than the patients with a PA increase when awake. The more synchronized (stages 3 + 4) and desynchronized (waking) cortical states influence the PA densities in such a way that there is a significant difference between both sub-groups. The PA density modulation found with the slow-wave sleep stages adds to that induced by sleep and waking states.

Adolescent↗
PubMed1983

[Sleep and dreams in patients with parietal and frontal lobe lesions].

Polygraphic recordings, psychological tests, and analyses of dreams during paradoxical sleep were conducted in 9 patients with parietal lobe, in 7 with frontal lobe lesions and in a control group. No significant differences in sleep organization were observed in the parietal group, but there was a considerable reduction in oneiric activity and alterations in results of some psychological tests. Several correlations based on statistical data are discussed. Oneiric activity was disorganized to a much lesser degree in patients with frontal lesions.

Adult↗
PubMed1982

Organization and role of platelet membrane phospholipids as studied with phospholipases A2 from various venoms and phospholipases C from bacterial origin.

Phospholipases A2 from various snake or bee venoms and phospholipases C secreted as exotoxins by several bacteria have been used to study the transverse distribution of phospholipids in the platelet plasma membrane and their role in platelet activation. An asymmetric distribution was described for phospholipids, characterized by a preferential localization of sphingomyelin and phosphatidylcholine in plasma membrane outer leaflet, whereas the inner half contains almost all of the anionic procoagulant phosphatidylserine and phosphatidylinositol. Such a distribution might explain the latency of procoagulant activity in resting platelets and implies an intracellular localization of arachidonic acid, the precursor of prostaglandins and thromboxanes. The external arachidonic acid is involved in phospholipase A2-induced aggregation, whereas phospholipase C from Clostridium welchii stimulates platelets through a thromboxane-independent pathway. The latter one is directly linked to the formation of phosphatidic and lysophosphatidic acids, which are able to activate cells through calcium mobilization. So, phospholipase C represents an interesting tool for studying the biochemical processes accompanying stimulation, since it is shown that it mimics the effects of an intracellular phospholipase C, the role of which in platelet activation is discussed.

Animals↗
PubMed1982

[Various factors affecting the onset of paroxysmal nocturnal interictal activities in primary generalized epilepsy in adults].

The relationships between the states of vigilance and the interictal EEG, paroxysmal activities (PA) were studied in 20 adults with generalized primary epilepsy. Each patient was submitted to 1-5 nocturnal polygraphic recordings. Sleep and waking modify the PA densities: 8 patients had a waking PA increase, 7 a sleep PA increase and 5 exhibited no differences of PA density between sleep and waking. Within these groups there was also an influence of slow wave sleep stages on PA densities. The function of auto-correlation of PA did not exhibit any periodicity even after correction of the effects of the states of vigilance. In patients monitored several nights the evolution of the PA densities during the successive sleep cycles throughout the night did not usually reveal a clear and stable pattern.

Adolescent↗
PubMed1981

[The place of Gelineau's syndrome (narcolepsy) among diurnal attacks of sleep and somnolence (author's transl)].

A clinical and electroencephalographic study was conducted in 41 patients (25 men and 16 women) complaining of diurnal attacks of sleep, and the results were compared with those obtained in 15 control subjects (7 men and 8 women) of the same age. EEG tracings were recorded during 33 hours in each subject. The total duration of the various phases of nocturnal sleep and the mean duration of each phase were the same in both groups. The incidence of EEG peculiarities, such as short delay in the onset of sleep and in the first stage of desynchronized sleep, and prolonged nocturnal periods of vigilance, was assessed in both groups, but no correlation was found between clinical and electrical data. The three criteria of Gelineau's syndrome (irresistible sleepiness, cataplexy and onset of sleep in desynchronized phase) were present in 35% of the patients.

Adult↗
PubMed1981

Studies on topological distribution of arachidonic acid replacement in platelet phospholipids and on enzymes involved in the phospholipid effect accompanying platelet activation.

In this short review recent results obtained on platelet phospholipid metabolism are summarized. The first part reports a topological study of arachidonic acid (AA) replacement in platelet phospholipids. It is shown that incubation of platelets with radioactive free arachidonic acid leads to a labelling of the phospholipids present inside the platelet, whereas the exchange of intact phosphatidylcholine (PC) molecules with the plasma lipoproteins occurs on the platelet outer surface. This should allow a selective labelling of the small external pool of AA in order to follow its behaviour during platelet activation. In the second part, some enzymes involved in the metabolism of phosphatidylinositol (PI) have been further characterized. The first one is a diglyceride-lipase, which is located in the plasma membrane and releases the two fatty acids esterifying the diglycerides formed from PI by the action of the platelet phospholipase C. Such an enzyme is probably responsible for the release of AA from PI occurring upon platelet activation. On the other hand, cytosolic phospholipid exchange proteins able to catalyse the transfer of PI between membranes have been identified. The possible role of the enzymes involved in the acceleration of PI turnover occurring during platelet activation is discussed.

Arachidonic Acid↗
PubMed1981

[Acquired aphasia in epileptic children--four cases with electrical infraclinic status epilepticus during sleep (author's transl)].

Four cases of acquired aphasia in epileptic children, associated with sub-continuous bitemporal paroxysmal activities (PA) during sleep, are described. Clinical improvement always followed the decrease or the unilateralization of PA. Persistence or aggravation of aphasia was observed when PA again became bitemporal and sub-continuous. Electroencephalographic characteristics of PA during sleep stages are described. Relationships of these cases with the 'sub-clinical electrical status epilepticus induced by sleep' and the physiopathology of aphasia are discussed.

Aphasia↗
PubMed1981

Effect of salbutamol, a putative cerebral beta agonist on sleep stages and interictal epileptic discharges.

The effects of Salbutamol 1.5 mg in 250 ml dextrose solution was tested on 14 epileptic patients following a double blind cross-over design. Sleep parameters and interictal paroxysmal activities density were measured. No seizures were encountered during the experiment. No modification of either sleep parameters (duration of sleep stages, latency of sleep and paradoxical sleep, duration of sleep cycles and awaking) or density of P. A. during waking state, on stage I, II, III and IV and paradoxical sleep were observed. In other respects, 5 patients had no P. A. during polygraphic sessions. They exhibited a longer duration of paradoxical sleep and a shorter duration of awaking than the 9 other patients with P. A. So with the dosage used here no implication of central beta-adrenoceptors in sleep mechanisms and production of epileptic activity are suggested.

Albuterol↗
PubMed1980

Event-related potentials evoked by sensory stimulation in normal mentally retarded and autistic children.

Evoked potentials (EPs) and slow potentials (SPs) were recorded during two sessions of sound (S) and light (L) conditioning (habituation: S alone; conditioning: coupling of SL; extinction: S alone after SL series). 125 children from 0 to 15 were examined: 82 exhibited signs of autistic behaviour and/or mental retardation; 43 were normally adapted. Two studies were performed. The first was an analysis of relationships: 65 clinical characters were noted for each child with behaviour scales and psychometric tests, 88 electrophysiological data were measured on averaged tracings. The second compared with t and chi 2 square methods the electrophysiological data of 3 groups clinically defined for age and typical syndrome. Results of the two studies supplemented each other. From the clinical point of view 3 major groups appeared: (1) autism, (2) mental retardation, (3) normal adaptation. From an electrophysiological point of view 2 major groups could be defined: (1) few conditioned EPs with small amplitude, generalized conditioned SPs, small unconditioned EPs, generalized unconditioned SPs, conditioning 'to time'; (2) many conditioned EPs, many conditioned rhythmic potentials, absence of generalized SPs, many localized vertex negative SPs (CNVs), large unconditioned EPs, no conditioning to time. Some differences were observed in generalized SPs, small and positive in mentally retarded children, negative or positive in autistic children. EP and SP data clearly help to differentiate pathological groups from a normal group but are insufficient to distinguish the autistic from the mentally retarded children.

Adolescent↗
PubMed1980

[Psychophysiological regin for rehabilition of chronic polydrug users in the Center of the Le Patriarche. 446 cases (author's transl)].

From 1974 to 1979, the rehabilitation centers of the association "Le Patriarche" located in the country side of southern France, have received 446 chronic polydrugs users who has consumed at one time or an other cannabis (marihuana, hashish) (87 p. cent), LSD (66 p. cent) and other hallucinogens (35 p. cent), psychodepressants (55 p. cent), psychostimulants (amphetamines, 85 p. cent; cocaïne, 50 p. cent) and opium and its derivatives (brown sugar, 47 p. cent; opiates, 67 p. cent; heroin, 50 p. cent). The dominant addictive drug was heroin and opiates, 52 p. cent, psychodepressants (barbitutiques and benzodiazepines, 33 p. cent, psychostimulants, 15 p. cent. Males were twice as numerous as female. Average age was 21 (range 14-38). Mean duration of drug abuse was 7 years. All these drug abusers display at entrance withdrawal symptoms. These were treated successfully by a drug free, psycho-physiological regimen comprising: 1. An elimination of all psychoactive drugs, including coffee, and alcohol. Tobacco was permitted. 2. Physical therapy (bath, exercise, massage) and forced fluid diuresis. 3. A supportive psychotherapy dispensed by rehabilitated addicts who had undergone successfully a similar regimen. This non-pharmacological method of treating withdrawal symptoms associated with opium, barbiturate and amphetamine addiction, was successful, and was not associated with any major clinical symptoms threatening the vital signs. Mean duration of detoxification was 5 days for opiates, 6 days for amphetamines and 10 days for barbiturates. 78 p. cent of these subjects remained in the centers from 3 months to 2 years, partaking in physical occupational and physiological rehabilitation paograms which allowed then to adopt a drug free life style and prepared them for social reinsertion.

Adolescent↗