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Biomedical subjects

O Benoit

Publications and source records attributed to O Benoit.

18 recordsLinked to original sources
PubMed1992

Sleep apneas in high altitude residents (3,800 m).

The question is: to what extent periodic breathing usually observed in translocated subjects at high altitude affects normal and polycythemic residents of high altitude? Standard sleep parameters, chest wall movements, temperature of ventilated gas and arterial O2 saturation (SaO2) were continuously recorded in 7 normal highlanders (mean hematocrit: 51%) and 14 polycythemic highlanders (mean hematocrit: 68%) during one night in La Paz, 3,850 m, Bolivia. The patterns of breathing instability were analysed by two ways: measuring duration of apneas and counting all the oscillations of SaO2 greater than 1%. Normal and polycythemic highlanders displayed a wide intersubject variability with regard to breathing instability, hence no significant difference in the total number of apneas and oscillations of SaO2 could be evidenced between the 2 groups. However, the longest apneas and the highest number of oscillations of SaO2 were found in the polycythemic highlanders.

Adaptation, Physiological↗
PubMed1992

Effects of a two-hour early awakening and of bright light exposure on plasma patterns of cortisol, melatonin, prolactin and testosterone in man.

Bright light is a synchronizing agent that entrains human circadian rhythms and modifies various endocrine and neuroendocrine functions. The aim of the present study was to determine whether and how the exposure to a bright light stimulus during the 2 h following a 2 h earlier awakening could modify the disturbance induced by the the sleep deprivation on the plasma patterns of hormones whose secretion is sensitive to light and/or sleep, namely melatonin, prolactin, cortisol and testosterone. Six healthy and synchronized (lights on: 07.00-23.00) male students (22.5 +/- 1.1 years) with normal psychological profiles volunteered for the study in winter. The protocol consisted of a baseline control night (customary sleep schedule) followed by three shortened nights with a rising at 05.00 and a 2 h exposure to either dim light (50 lux; one week) or bright light (2000 lux; other week). Our study showed a phase advance of the circadian rhythm of plasma cortisol without significant modifications of the hormone mean or peak concentration. Plasma melatonin concentration decreased following bright light exposure, whereas no obvious modifications of plasma testosterone or prolactin patterns could be observed in this protocol.

Adult↗
PubMed1991

Hypnotics and sleep physiology: a consensus report. European Sleep Research Society, Committee on Hypnotics and Sleep Physiology.

The effects of hypnotics on descriptive and functional aspects of electrophysiological sleep parameters are assessed in this report. Because of the arbitrary definition of some of the criteria underlying the conventional sleep stage scoring procedure, computer-aided methods of EEG analysis have become increasingly important for recording and interpreting pharmacological effects on sleep. Of particular interest are the changes of EEG slow-wave activity, since this parameter varies as a function of prior sleep and waking. Several types of interaction between hypnotics and sleep regulation are discussed, some recent pharmacological developments are highlighted, and some common problems in clinical trials are specified.

Anti-Anxiety Agents↗
PubMed1991

[Benefits and risks of hypnotics].

Rationalisation of the war of hypnotics has recently been under discussion in France: a review of the benefits and risks of these substances may therefore be useful. Chronic insomnia is a result of multiple factors, among which individual characteristics of the personality play an important role. Hypnotic treatment is symptomatic; its beneficial influence on sleep progressively vanishes in few weeks, while some negative residual effects on daytime functioning (mood, alertness, performance, memory impairment) may persist. The main problems posed by hypnotic treatment with benzodiazepines are related to tolerance effects during the treatment period and to rebound insomnia and withdrawal phenomena after discontinuation. Practical issues for the treatment of insomnia, based on international consensus, are presented.

France↗
PubMed1990

Modifications of sleep structure by brief forced awakenings at different times of the night.

Four subjects were awakened once a night for 10 min at either 01.30, 03.30 or 05.30 h. During the waking intervals, they performed a mental task while remaining in bed. The awakenings did not significantly modify the amount of different stages during subsequent sleep with no effect of time of occurrence in the night. In contrast, the timing of the awakening within the cycle had a significant influence on REM cycle structure. If awakening occurred during a REM episode or shortly thereafter, the following inter-REM interval was shortened; if it occurred late in the cycle, that is shortly before a REM episode, it increased the inter-REM interval beyond the reference length of the corresponding uninterrupted cycle. An explanation based on a model of sleep which implies the simultaneous activity of REM-on and REM-off neurones is proposed.

Adult↗
PubMed1990

Psychophysiological effects of early morning bright light exposure in young adults.

The effects of bright light on circadian rhythms in man are well documented. Nevertheless the theoretical basis and the rules for the practical utilization of light exposure as therapy need still to be better defined. The present study determined to what extent a 2-hr bright light exposure (0500-0700 h) improved the adjustment to an early rising in normal adults. Phase changes were assessed in subjective alertness, performance in several search tasks, time estimation, and a visual discrimination task, as well as in body motility, plasma cortisol concentrations, and body temperature. In comparison with a dim light exposure, the bright light resulted in increased motor activity during waking, in earlier peak of subjective alertness, and an improvement in performance speed in three out of five tasks in the morning. Cortisol and body temperature also were phase-advanced. In summary, light applied to a portion of the circadian cycle sensitive to phase advance shifts influenced rhythms with strong endogenous components (temperature and cortisol), while other rhythms with strong exogenous components were more sensitive to sleep deprivation caused by the early rising time.

Adult↗
PubMed1990

The Multiple Sleep Latency Test: individual variability and time of day effect in normal young adults.

The influence of individual characteristics on diurnal physiological sleep tendency was investigated in young good sleepers. Fifty-five subjects underwent a Multiple Sleep Latency Test (MSLT) procedure. Among them 11 also participated in Repeated Test Sustained Wakefulness (RTSW) procedure. The MSLT results were analyzed as a function of both the number of sleep onsets per day and the time of day. Diurnal sleepiness seemed to be better appreciated by sleep onset (SO) frequency than by the traditional criteria of sleep latency. SO frequency, unlike latency, was influenced by factors such as usual sleep duration, morning/evening score, and RTSW procedure. Time of day effect was characterized by a decrease in sleep tendency at the beginning and at the end of the day (decrease in SO frequency and increase in SO latencies); between these two points a peak of sleepiness around 1400 was observed. The morning and evening periods of high alertness could represent important anchor points for the coupling of the sleep/wake and temperature rhythms.

Adult↗
PubMed1990

Periodic breathing and O2 saturation in relation to sleep stages at high altitude.

This study was designed to compare sleep organization at high altitude (HA) and sea level (SL) and to estimate the extent periodic breathing (PB) negatively influences arterial O2 saturation (SaO2). Six lowlanders were studied at SL and after 3 weeks spent at 3,800 m (La Paz, Bolivia). Three EEG leads, EOG, submental EMG, chest and abdominal motion, temperature of ventilated gas, and SaO2 were polygraphically recorded. Comparison of HA and SL data disclosed that: 1) Sleep organization was identical, with the same percentage of REM and stage 4. 2) PB (cycle length: 20 s; central apnea: 9 s) occurred in three subjects during all stages of sleep except REM (43-60% of total sleep). A periodic lowering in heart rate occurred during ventilatory oscillation. 3) During PB, SaO2 oscillated very regularly from 78-90%, which resulted in a mean SaO2 value calculated during oscillations similar to that of the non-periodic breathers. We conclude that lung O2 uptake during PB is preserved.

Altitude↗
PubMed1985

[Silicone inclusions in the spleen in a patient under chronic hemodialysis].

A 67-year-old woman with chronic renal failure, in periodic hemodialysis, presented an hemolytic anemia in relation to splenic sequestration. Light Microscopic examination of the spleen revealed multiple granulomatous reaction. Numerous macrophages contained inclusions which were non-birefringent and non-staining with routine stains. Electron microscopy, scanning electron microscopy and energy dispersive X-Ray analysis were performed and revealed silicone. Its origin was silicone tubing of the hemodialysis equipment. Pathogenic effects of silicone are discussed.

Aged↗
PubMed1978

[Study of sleep of shift workers with alternating schedules: adaptation and recovery in case of rapid shift rotation (3-4 days) (author's transl)].

An electroencephalographic study of the sleep of shift workers (3 x 8) was performed in a French oil refinery. The recordings of diurnal sleep showed: a severe disorganization of the first day sleep (very short duration, decrease of PS and SWS in absolute amount); a trend towards better sleep characteristics (duration, PS and SWS amount) through the day-sleep period. Recovery night sleep appeared different when following curtailed night sleep (morning shift) and when following curtailed day sleep (night shift). Nocturnal sleep following immediately the diurnal sleep shows only partly the characteristics of a real recovery. Thus there seems to be a beginning adaptation to schedule reversal. This result supports a rapid shift alternation (3-4 days) which restrains both the cumulated sleep deficit and the adaptation to schedule reversal.

Electroencephalography↗
PubMed1978

[Sleep in children with episodic sleep phenomena: a comparison with the normal child].

(1) The sleep pattern of 23 children, aged 5-12 years, with episodic nocturnal phenomena (night-terrors, somnambulism, rhythmic movements) was recorded during two successive nights. It was compared with that of a group of 21 normal children of the same age. (2) In the pathological group, slow wave sleep (SLP, stages 3 and 4) was significantly shortened during the 2 nights. This deficit mainly involved the first 3h of sleep. (3) As for the slow wave sleep, REM sleep (SP) modifications prevailed during the first hours of sleep. The first REM period was delayed and preceded by more numerous and atypical partial REM periods. The duration of the first REM period increased faster as a function of its latency than in the normal child. (4) In contrast with this difficulty for REM sleep to occur during the first part of the night, the subsequent REM sleep pattern was similar in the 2 groups (total REM sleep duration, mean REM period duration, mean REM cycle duration). For equal latencies, REM periods had similar duration. Finally, the total REM sleep amount was a linear function of the total sleep time, with more or less identical coefficients for the two groups. (5) The part played by these modifications during the first hours of sleep in the occurrence of night terrors and somnambulism is discussed.

Child↗
PubMed1977

[Reticular activity and intracranial pressure. Acute and chronic intracranial hypertension (author's transl)].

Modifications of mesencephalic and bulbar reticular formation activity were studied with microelectrodes during acute and chronic intracranial hypertension. In both cases, the mesencephalic reticular activity increased progressively until a pressure level of 70 to 90 cm of CSF was reached and then fell irreversibly to less than the base value. The bulbar reticular activity followed the same pattern but more slowly. Different hypotheses are advanced to explain these modifications and their meanings.

Animals↗
PubMedDate not supplied

[Respiration and night sleep in children "at risk" for sudden and unexpected death (author's transl)].

Polygraphic recordings were used to study respiration and night sleep in 26 such children. These children, who were "at risk" for sudden and unexpected death, could be divided into two groups : near-miss (NM) (15 cases), and those who were brothers, sisters, or cousins of a child who had died suddenly and unexpectedly (8 cases), or had periodic respiration (RP) (3 cases). No significant differences were found between the groups in respiratory tests, except for a significantly lower RP rate in the NM group and an increase in number of isolated pauses. Sleep organization was similar in both groups, though there was a significantly higher rate of active sleep (SA) in the NM group more than 2 months old. The highest respiratory indices were noted in the extreme cases of a non-NM group (including 2 brothers of infants who had died unexpectedly). Treatment with Diphemanil methylsulfate (Prantal) reduced the number of SA and respiratory pauses of the NM infants less than 2 months old.

Female↗