Biomedical subjects

M Tafti

Publications and source records attributed to M Tafti.

45 records · Page 3Linked to original sources

PubMed1993

[Polysomnography findings in middle-aged and elderly narcoleptics].

The comparison of 24 hours polysomnographic recordings of middle-aged narcoleptic subjects (39-51 years, group A) with 11 twenty four hours and 3 nighttime recordings of elderly narcoleptic subjects (aged 60-72 years, group B) using T test for non paired values was made. No difference was found in parameters of nighttime registrations: total sleep time (A:510.4 +/- 71.2 min., B: 475.9 +/- 92.4 min), intrasleep wakefulness (A: 107.5 +/- 75.3 min., B: 112.3 +/- 65.3 min), latencies of sleep stages (1NREM-A: 3.4 +/- 2.8 min, B: 4.3 +/- 3.7 min, 2NREM-A: 7.4 +/- 7.6 min, B: 6.6 +/- 12.7 min, 3NREM-A: 27.2 +/- 10.4 min, B: 51.6 +/- 62.6 min, REM-A: 62.2 +/- 59.5 min, B: 64.6 +/- 71.6 min), relative duration of each sleep stage (1NREM-A: 20.0 +/- 9.5%, B: 21.4 +/- 13.2%, 2NREM-A: 51.3 +/- 8.5%, B: 51.9 +/- 14.2%, 3 +/- 4NREM-A: 8.2 +/- 6.5%, B: 7.2 +/- 6.5%, REM-A: 20.4 +/- 4.5%, B: 19.1 +/- 5.7%), and sleep continuity index (A: 0.83 +/- 0.11, B: 0.81 +/- 0.11). Total sleep time in the daytime was similar (A: 160.5 +/- 53.8 min, B: 180.5 +/- 59.9 min), the number of sleep episodes during the day was in elderly patients higher (A: 3.4 +/- 1.2, B: 4.8 +/- 1.3, P < 0.05) and the number of sleep onset REM periods was in elderly subjects slightly higher (A: 1.9 +/- 1.1, B: 2.7 +/- 1.7). The authors conclude that the nocturnal sleep of both age groups of narcoleptic subjects is disturbed and the character and the intensity of this disturbance are similar. Elderly narcoleptic subjects displayed more daytime sleep periods.

Adult↗

PubMed1992

Sleep deprivation in narcoleptic subjects: effect on sleep stages and EEG power density.

Sleep of 8 narcoleptic and 8 control subjects was recorded under baseline (i.e., prior wakefulness 16 h) and after 24 h without sleep. During both baseline and recovery total sleep time and stage 2 non-REM sleep were significantly decreased in narcoleptic subjects. Slow wave activity (i.e., EEG power density in the range of 0.75-4.5 Hz) decayed exponentially during baseline and after sleep deprivation in both narcoleptic and control subjects. During both baseline and recovery EEG power density in delta and sigma frequencies in non-REM sleep was enhanced in narcoleptic subjects relative to controls. In REM sleep differences in the same direction were present in delta and beta frequencies. After sleep deprivation EEG power density in non-REM sleep was elevated in delta and some higher frequencies in both patients and controls, but the response to sleep deprivation was stronger in narcoleptic subjects. These data show that in narcoleptic subjects regulatory processes underlying non-REM sleep homeostasis are operative and indicate that the response to sleep deprivation is stronger than in control subjects.

Adolescent↗

PubMed1992

Effects of zopiclone on subjective evaluation of sleep and daytime alertness and on psychomotor and physical performance tests in athletes.

1. In a double-blind cross-over study 8 athletes received during 2 sessions of 2 nights zopiclone (7.5 mg) or placebo. 2. Residual effects on subsequent daytime functions were evaluated both subjectively by visual analogue scales as well as objectively by a test battery measuring psychomotor and physical skills. 3. Zopiclone had some favourable effects on self-estimated sleep quality and daytime sleepiness. 4. Psychomotor and physical performance tests did not show any significant difference between zopiclone and placebo. 5. We conclude that zopiclone has useful hypnotic activity without significant adverse effects on athletic performance.

Adult↗

PubMed1992

Sleep in human narcolepsy revisited with special reference to prior wakefulness duration.

Sleep of 11 narcoleptic subjects was recorded on baseline and after 16 and 24 hours of prior wakefulness (16 and 24 hours sleep deprivation). Eleven sex- and age-matched control subjects were recorded for comparisons. All recordings in narcoleptic subjects were characterized by frequent sleep onset rapid eye movement (REM) episodes, increased amounts of wake time after sleep onset and low sleep efficiencies. Mean total sleep time (TST) was significantly decreased in narcoleptic subjects after sleep deprivation (SD). Recovery sleep after 24 hours SD showed reduced nonREM (NREM) sleep stage 2 percentage, whereas percentages of stage 4 and slow-wave sleep (SWS = stages 3 + 4) were significantly increased. The values of REM sleep percentage of TST were remarkably constant throughout and did not differ significantly as a function of experimental conditions, indicating a normal REM sleep pressure in narcolepsy. Sleep stage analysis per sleep cycles revealed significant differences between the two groups. Percentages of stage 4 and SWS were increased during the first cycle of recovery sleep in narcoleptic subjects. Stage 2 was decreased during the third cycle, and SWS decreased rapidly from cycle 1 to cycle 2 and slightly increased thereafter. These results indicate that sleep need is increased in narcolepsy, whereas its decrease over the first NREM-REM cycle is accelerated. We hypothesize that this could reflect an alteration of the homeostatic process of sleep regulation in narcolepsy.

Adolescent↗

PubMed1992

Sleep onset rapid-eye-movement episodes in narcolepsy: REM sleep pressure or nonREM-REM sleep dysregulation?

Thirty-two narcoleptic subjects with excessive daytime sleepiness and cataplexy were recorded for 33 continuous hours. The continuous polysomnographic recording (CPSG) was followed by a standard MSLT at 2-h intervals. There were 64 sleep onset REM episodes (SOREMs) vs 64 sleep onset nonREM episodes (SONREMs) during the CPSG, and 102 SOREMs vs 50 SONREMS during the MSLT. Both sleep onset types peaked at 13-15 h during the CPSG while sleep onsets were evenly distributed during the MSLT. In the latter procedure, the mean sleep latency was significantly shorter with SOREMs occurrence than with SONREMs occurrence. Two factors were extracted in each procedure by means of a Varimax Rotated Factor Analysis. During the CPSG, SOREMs were related to the preceding nocturnal sleep parameters in the first factor, and to the daytime total sleep time and the total number of sleep onsets in the second factor. During the MSLT, SOREMs were related only to the mean sleep latency and the total number of sleep onsets. It was concluded that the occurrence of SOREMs is primarily due to the residual somnolence in narcoleptic subjects. However, their occurrence during the MSLT is largely independent of the prior history of sleep and waking. Thus, we propose a nonREM-REM sleep dysregulation hypothesis to account for the appearance of SOREMs in narcolepsy.

Journal Article↗

PubMed1992

Respiratory variation of the ballistocardiogram during increased respiratory load and voluntary central apnoea.

Heavy snoring is associated with increased respiratory variation of the ballistocardiogram (BCG). The cause for this association is not known. Although the BCG is a sensitive method to measure myocardial performance, the validity of the signal as a marker of snoring-related haemodynamic changes has not been tested. The aim of this study was to investigate whether ballistocardiographic respiratory variation (BRV) correlates with intrathoracic pressure variation (IPV). The BRV and the IPV were measured in five healthy, normal-weight, awake adults during normal breathing, during breath-holding with constant intrathoracic pressure, and during breathing against increased respiratory resistance (high IPV). The BCG was recorded with the static charge-sensitive bed (SCSB) and the intrathoracic pressure with an oesophageal balloon. The mean BRV was significantly lower during central apnoea than during free breathing (8.2 versus 29.4% p less than 0.0001). When breathing against increased respiratory load, the BRV increased in a linear manner as function of the IPV (r = 0.68, p less than 0.01). There was significant interindividual variation in the response. We conclude that changes in the BRV reflect changes in the IPV. Further studies are needed to evaluate whether the BCG could be used as a noninvasive alternative to the oesophageal balloon in monitoring changes of respiratory resistance during heavy snoring.

Adult↗

PubMed1991

Why don't all heavy snorers have obstructive sleep apnea?

Patients with obstructive sleep apnea (OSA) and heavy snorers without apnea both show intrathoracic suction pressures during sleep that exceed their static upper airway closing pressures. Complete airway occlusion, however, occurs only in the former patient group. We hypothesized that the kinetic properties of the airflow would be different in these two types of patients because of differences in upper airway morphology. The pharyngeal computed tomography (CT) was used to measure the cross-sectional areas of the upper airways in 15 patients with OSA, 25 nonapneic heavy snorers, and 14 control subjects while they were awake. Nocturnal breathing was monitored with the static charge-sensitive bed (SCSB). The patients with OSA had a narrower airspace at the velopharyngeal (VP) level than the controls (p less than 0.01); the nonapneic snorers did not differ from the other groups. At the tongue base (TB) and the hyoid bone (HB) levels there was no difference between the OSA and the control groups, but the nonapneic snorers had narrower airways at both of these levels compared with control subjects (p less than 0.01) and at the hyoid bone level compared with the OSA group (p less than 0.05). The VP/HB ratio was the parameter that best distinguished the patients with OSA from the nonapneic snorers (lower in the OSA group, p less than 0.001). We suggest that airway collapse during sleep is favored by a narrow velopharynx associated with large hypopharynx. Some heavy snorers may not have an oropharyngeal collapse because the peak inspiratory suction pressure could already be damped down at the level of the relatively narrow hypopharyngeal airways.

Airway Resistance↗

PubMed1990

Skeletal muscle extracts promote the survival of neurofilament-positive mammalian sensory neurons.

Cultured neurons of the mammalian dorsal root ganglia (DRG) can be divided, as in intact ganglia, into two classes: 'large light' (neurofilament-positive) and 'small dark' (neurofilament-negative) neurons. While 'small dark' neuron survival depends on NGF during ontogenesis, little is known about the neurotrophic factor requirement of the 'large light' sub-population. This study demonstrates that the in vitro survival of neonatal mammalian neurofilament-positive DRG neurons requires the presence of a neurotrophic factor present in skeletal muscle extract.

Animals↗

PubMed1989

[A world record in marathon tennis: sleep deprivation and performance].

We studied the effects of marked sleep deprivation on the EEG patterns and performance of a physically fit man (age 26) on the occasion of the world record continuous marathon tennis play (147 hours, 20 minutes). Before and immediately after the marathon, the sleep patterns of the player were recorded in our laboratory. After playing for 40 and 80 hours and within 24 hours, the performance changes were evaluated each hour. Amounts of the different sleep stages during the first recovery night compared with those of the baseline indicate an increase of 56% for total sleep time, 54% for stages 1 and 2, 154% for stages 3 and 4 and 20% for REM sleep. During the second recovery night, only REM sleep showed an increase. Activity index showed a marked decrease after 80 hours of sleep deprivation compared with that after 40 hours and was dramatically worsened during nighttime. The number of faults and pauses was also increased after 80 hours, suggesting a clear performance deterioration. Our results confirmed the effects of sleep deprivation on the recovery and performance deterioration.

Adult↗