Funciones neurocognitivas alteradas en paciente intoxicada por monóxido de carbono / Altered neurocognitive functions in a patient with carbon monoxide poisoning

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Sleep and wakefulness in the green iguanid lizard (Iguana iguana).

The reptile Iguana iguana exhibits four states of vigilance: active wakefulness (AW), quiet wakefulness (QW), quiet sleep (QS) and active sleep (AS). Cerebral activity decreases in amplitude and frequency when passing from wakefulness to QS. Both parameters show a slight increase during AS. Heart rate is at a maximum during AW (43.8+/-7.9 beats/min), decreases to a minimum in QS (25.3+/-3.2 beats/min) and increases in AS (36.1+/-5.7 beats/min). Tonical and phasical muscular activity is present in wakefulness, decreases or disappears in QS and reappears in AS. Single or conjugate ocular movements are observed during wakefulness, then disappear in QS and abruptly reappear in AS. Although these reptiles are polyphasic, their sleep shows a tendency to concentrate between 20:00 and 8:00 h. Quiet sleep occupies the greater percentage of the total sleep time. Active sleep episodes are of very short duration, showing an average of 21.5+/-4.9 (mean+/-SD). Compensatory increment of sleep following its total deprivation was significant only for QS. Reaction to stimuli decreased significantly when passing from wakefulness to sleep. It is suggested that the lizard I. iguana displays two sleep phases behaviorally and somatovegetatively similar to slow wave sleep and paradoxical sleep in birds and mammals.

Topographical distribution of the locus coeruleus and raphe nuclei in the lizard Ctenosaura pectinata: functional implications on sleep.

The nature of sleep in reptiles has traditionally created intense discussion and has originated some controversy. Nevertheless, some authors have described a sleep phase analogous to sleep in endotherm vertebrates. It is known that in mammals, the locus coeruleus and raphe nuclei, located in the brain stem, are functionally related to the sates vigilance regulation. In contrast the presence of two sleep phases in the lizard Ctenosaura pectinata similar to slow wave sleep and rapid eye movement sleep have been described. Therefore we carried out studies of the brain stem of C. pectinata to search for cellular groupings related to the regulation of these sleep phases. We identified and described the topographical distribution of the locus coeruleus and raphe nuclei in the lizard C. pectinata. Results show that these nuclei that have been functionally related to vigilance states in mammals, are also present in C. pectinata. These nuclei are formed by fairly well defined cellular groupings placed in the brain stem.

Sleep patterns of the volcano mouse (Neotomodon alstoni alstoni).

Sleep-waking patterns of the volcano mouse were studied under laboratory conditions. This rodent exhibits four states of vigilance: active wakefulness (Aw), quiet wakefulness (Qw), slow-wave sleep (SWS), and paradoxical (PS), or rapid-eye movement (REM) sleep. These states present, in general, the classic mammalian electrophysiological patterns. Although sleep periods were distributed at any time of the nychthemeral cycle, they showed the tendency to concentrate between 0800 and 2000 hours. The volcano mouse may be considered as a "good" sleeper, because it shows a relatively high percentage of sleep from the total recording time (TRT). Slow-wave sleep occupied 64.54 +/- 8.84% (mean +/- SD) of the total recording time, while 7.56 +/- 1.31% corresponded to rapid-eye movement sleep. The average duration of the rapid-eye movement sleep phase was 126.48 +/- 17.79 s, exhibiting an average recurrence of 49 +/- 9.28 phases throughout the nychthemeral cycle. Mean duration of the sleep cycle was 9.23 +/- 2.36 min. Quantitative data of the volcano mouse sleep may be considered adequate for its body size and characteristic of an animal which sleeps in secure places under free-living conditions.

Effect of p-chlorophenylalanine (PCPA) on sleep and monoamines content in the brain of a lizard species.

Administration of PCPA, a specific inhibitor of serotonin synthesis, induced a significant decrease of total sleep time in the lizard Ctenosaura pectinata. This effect was exerted on both quiet sleep and active sleep, but it was more intense on active sleep. Reduction in the amount of active sleep was due to a decrease in the number of the episodes not in their mean duration, since this parameter increased significantly from 5.97 s, under control conditions, to 11.77 s, 10.66 s and 8.85 s at 24, 48 and 72 h after PCPA injection, respectively. Neurochemical analysis showed a significant decrease in the amount of serotonin in the analyzed brain stem structures 12 h after PCPA administration. The possible participation of serotonergic mechanisms in the regulation of reptilian sleep is discussed.

Cerebral death induced by electrical current.

Application of a 126 V, 3 Ampers electrical current produces brain death in dogs assessed by irreversible installation of an isoelectric electroencephalogram. Cerebral death was immediate or preceded by a paroxistic activity of short duration (25 +/- 12 Seconds; Mean +/- SD). Besides the isoelectric electroencephalogram, there were immediate respiratory arrest and cardiac fibrillations followed by heart stopping. Reflexes were absent and no response to painful stimuli was observed. An appropriate utilization of the experimental method described in this study may contribute to improve the knowledge about the pathophysiology of cerebral death in humans.

[Effects of 1,5 benzodiazepine beta lactam on sleep]. / Efecto de una beta lactama de 1.5 benzodiazepina sobre el sueño.

Various substances have been used as sleep inductors, but their use has declined, due to their undesirable side effects, and they have been replaced mainly by benzodiazepines. There currently exists a great variety of benzodiazepines with an increasing, clinical use, although they also present certain disadvantages. The effect on sleep of the intraperitoneal administration (0.9 mg/kg) of 7-(p-cl-phenyl)-8-phenoxy-4,5-benzo-3-aza-2-none, was analysed in chronically implanted wistar rats. Results indicate that this substance decreases wakefulness and increases significantly slow-wave and paradoxical sleep. Latency of the first phase of paradoxical sleep show a tendency to increase. It is concluded that this substance has hypnogenic effects.