Search PubMed⌕ Search

Biomedical subjects

R Ursin

Publications and source records attributed to R Ursin.

54 records · Page 3Linked to original sources
PubMed1983

REM-NREM cycle in the cat may be sleep-dependent.

The periodicity of the rapid eye movement-nonrapid eye movement (REM-NREM) cycle in real time versus compressed sleep was determined by autocorrelation, computed on the sequence of sleep stages in recordings from spontaneously sleeping cats. The resulting autocorrelation function was correlated to damped cosine waves, and the highest squared correlation coefficient (r2) was taken as indicating the most likely periodicity in the data entered for each animal. The periodicity of REM sleep was stronger (significantly higher r2) in the compressed sleep data than in the real-time data, indicating sleep dependency of the REM-NREM cycle. The REM-NREM cycle lengths determined by the autocorrelation technique were not significantly different for the real-time and compressed sleep data. The REM sleep episode interval, defined as the average interval between the start of successive REM sleep episodes, was significantly shorter for real-time sustained sleep than the cycle lengths as determined by the autocorrelation technique. A model is proposed which explains this phenomenon as due to fragmentation of REM sleep within the time periods with high probability for REM sleep. When such fragmentation occurs, the average REM sleep episode interval will not reflect an ultradian REM sleep periodicity.

Animals↗
PubMed1982

Sleep deprivation procedure produces stomach lesions in rats.

Sprague-Dawley male rats were deprived of food for 40 hr and subjected to sleep deprivation by the "flower pot" or handling intervention procedures during the final 24 hr. Five of six rats in the flower pot group exhibited stomach erosions. Only one rat in the handling group, and no rats in a food deprived control group showed such erosions. The flower pot group also had higher levels of corticosterone than the food deprived control group. These findings argue for more serious consideration of the effects of the stress of procedures for sleep deprivation.

Animals↗
PubMed1982

Effect of high pressure on EEG burst suppression dose of thiopental in rats.

The anesthetic induction dose of thiopental in rats was studied at 1 ATA air, 1 ATA helium-oxygen (He-O2), 4 ATA air, and at 4 ATA air plus 67 ATA helium (71 ATA). The compression rate was 0.3 ATA/min, and 1 h was spent at pressure before the experiment started. Thiopental was infused at a rate of 7.5 mg X kg-1 X min-1. The depth of anesthesia was assessed by electroencephalographic (EEG) recording using burst suppression of 1 s as the biological end point. The mean induction dose at 1 ATA air was 53.1 mg/kg and at 71 ATA was 74.7 mg/kg, an increase of 41%. The induction doses at 1 ATA He-O2 and 4 ATA air were 46.4 mg/kg and 45.3 mg/kg, respectively.

Animals↗
PubMed1980

Awakening thresholds for electrical brain stimulation in five sleep-waking stages in the cat.

Awakening thresholds during the different stages of a particular 5-stage sleep-waking classification in the cat were determined by electrical stimulation through electrodes implanted in the brain. Only areas from which orienting behaviour was elicited when stimulated during the alert waking (W-1) stage were used for the awakening threshold studies. The stages compared with W-1 were W-2, SWS-1, SWS-2 and REM sleep. There were stepwise increments in the awakening thresholds from one stage to the next in the predicted order from W-2 to REM sleep. There was some variation between structures, but the threshold increments were consistent and support the validity of the 5-stage sleep-waking classification.

Amygdala↗
PubMed1976

The effects of 5-hydroxytryptophan and L-tryptophan on wakefulness and sleep patterns in the cat.

Sleep in cats was studied for 24 h after i.p. injections of D,L-5-hydroxytryptophan (5-HTP, 40 mg/kg) or L-tryptophan (200 mg/kg and 300 mg/kg) in two separate experiments. Total sleep, total slow wave sleep or deep slow wave sleep was not changed in any experiment. There was an increase of the awake, drowsy pattern over the whole recording period after both 5-HTP and tryptophan injections. An accentuated drowsy pattern, with high voltage 4 c/sec synchronous waves, but with no sleep spindles, was seen during the first hours after 5-HTP injection. REM sleep was completely absent during the first 6 h after 5-HTP and significantly reduced during the first 3 h after tryptophan. The similarity of the effects of 5-HTP and tryptophan suggests that they both act as serotonin precursors. It is also suggested that the serotonin precursors have a general deactivating effect on the waking state, and that they do not necessarily subserve a specific sleep-inducing or sleep-maintaining function.

5-Hydroxytryptophan↗
PubMed1976

Effects of sleep of restricted sleep. A cat case study.

One male cat was adapted to different schedules of restricted sleep. The cat was allowed to go to sleep during a certain number of hours per day. During the rest of the 24 h period, wakefulness was enforced by means of a treadmill. The following schedules of restricted sleep were run: 12 h sleep--12 h treadmill (12S--12T), 8S--16T, 4S--20T. The cat was also adapted to a 36 h day: 12S--24T. The sleep was investigated after at least 2 weeks on each schedule and compared to ad lib. sleep (24S--0T). As available sleep time bacame shorter, the composition of the sleep changed. LSWS (in % of available sleep time) decreased, while DSWS % and REM sleep % increased. The length of the DSWS and REM sleep episodes increased with decreasing sleep time, as did sleep cycle length.

Animals↗
PubMedDate not supplied

Does para-chlorophenylalanine produce disturbed waking, disturbed sleep or activation by ponto-geniculo-occipital waves in cats?

Sleep-waking stages and PGO activity were continuously recorded for 2 days following a control injection and for 5 days following a single injection of 200 mg/kg PCPA. Following PCPA, quiet waking with desynchronized EEG activity (W-1 quiet) was increased, while waking with synchronous EEG activity (W-2) was reduced dramatically. Active waking (W-1 active) was not changed. Sleep was reduced following PCPA, in particular slow wave sleep with slow synchronous waves (SWS-2). The distribution of PGO activity on the sleep-waking stages was altered after PCPA. The sleep-waking changes preceded the PGO wave redistribution by 12--18 hours. The data do not support the PGO wave activation hypothesis for the sleep loss following PCPA administration. It is concluded that PCPA affects a deactivating, possibly slow wave producing mechanism, affecting relaxed waking and deep slow wave sleep but not sleep per se.

Animals↗