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Biomedical subjects

E A Lucas

Publications and source records attributed to E A Lucas.

36 records · Page 2Linked to original sources
PubMed1985

Sleep apnea and the Arnold-Chiari malformation.

We present a polysomnogram-documented report of central sleep apnea (427 events) and moderately severe decreases in arterial oxygen saturation (to 81%) associated with the Arnold-Chiari malformation (ACM). Daytime hypersomnolence and other symptoms had significantly impaired our patient's work performance. After surgical correction of the ACM, there was marked improvement in symptomatology. A post-surgery polysomnogram revealed marked improvement in the number of central apneas (74 events) and only mild decreases in oxygen saturation (to 94%).

Arnold-Chiari Malformation↗
PubMed1985

The respiratory response to stimulation of juxta-pulmonary capillary receptors in the non-anesthetized cat.

To avoid the modifying influence of general anesthesia on vagal control of respiration, we investigated the effect of phenyldiguanide (PDG), a drug known to stimulate juxta-pulmonary capillary ("J") receptors, in the non-anesthetized, unrestrained cat and recorded EEG, eye movements, neck muscle EMG, EKG and respiratory movements. The response to bolus injection of PDG into the right atrium was qualitatively similar to the one seen in cats under anesthesia, consisting of bradycardia and apnea followed by rapid shallow breathing (RSB). The injection-response latencies ranged from 1.5 to 3 s, indicating that the effect originated on the venous side of the cardiopulmonary region. Vagal block with lidocaine, which was applied via external tubings feeding into implanted vagal "sleeves", abolished the responses to PDG, demonstrating their dependence on vagal mediation. Atropine blocked the bradycardia but did not affect the apnea. All doses of PDG which affected respiration uniformly produced initial apnea, whose duration, in any given animal and trial session, exhibited a consistent dose-response relationship. Slow injections also produced apnea. RSB following the apnea was variable in frequency and amplitude of excursions and in its overall duration, and failed to reveal a dose-response relationship. Apnea lasted significantly longer when injections were made during slow wave sleep or REM sleep as compared to injections given during wakefulness or drowsiness. Arousal from all states of sleep occurred simultaneously with the onset of apnea and bradycardia and was also dependent on the vagi. Spontaneous awakening from sleep, by contrast, was always associated with an increase in breathing.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1980

Effect of amphetamine and pentobarbital on sleep-wake patterns of cats with basal forebrain lesions.

The effects of amphetamine and pentobarbital upon electrographic state were studied in naive cats and cats with forebrain lesions that induce insomnia. Amphetamine increased alertness and decreased both slow wave sleep (SWS) and rapid eye movement (REM) sleep states for up to 12 h in both intact animals and cats with lesions. Pentobarbital inhibited REM sleep and alert states while increasing SWS and drowsy states in naive cats. The effect was mainly restricted to the first 8 h. In cats with forebrain lesions, the effects were similar except that the amount of REM sleep was significantly elevated. During a portion of the first 8 h, the tracing cannot be distinguished from a normal control sample. It is hypothesized that pentobarbital mimics the normal inhibitory influence of the intact forebrain and either induces or facilitates 'normal' sleep patterns in cats with forebrain lesions.

Amphetamine↗
PubMed1979

Effects of a short light-dark cycle on the sleep-wake patterns of the cat.

The purpose of this study was to measure the effect of a short, 106 min, light-dark (LD) cycle on the sleep-wake (SW) patterns of the cat. Eight cats prepared for chronic sleep studies were observed with electrographic tracings for 48 hr on a regular 12:12 hr LD schedule and again after 2 weeks of adaptation to a 27 min light and 79 min dark schedule. Each 1 min of data was scored as either alert, drowsy, slow wave sleep (SWS) or REM sleep. The parameters studied were percent electrographic state, state epoch length, polycyclic SW cycle, and mean vigilance. The short LD cycle caused a significant increase in alert state accompanied by reductions in drowsy, SWS, and REM sleep states. Although the effect was more pronounced during lights-on intervals, the trend was also present in dark intervals. Alert episodes of about all lengths increased. There were decreases in longer episodes of the other three states and a tendency for shorter episodes to increase in number. Episodes of the polycyclic SW cycle did not tend to follow the short LD cycle. The mean length of both sleep and wake episodes increased rather than decreased. However, mean vigilance values increased toward wakefulness at or near the light interval. Analyses showed that both the amplitude and phase relationship of this increase was significantly related to the 27 min light interval in comparison to base-line data. It was hypothesized that both light-dark and dark-light transitions represent alerting cues to the cat. Differences between the SW response of the cat and the rat to LD cycles are discussed.

Animals↗
PubMed1977

Baseline sleep-wake patterns in the pointer dog.

The 24-hr electrographic patterns (EEG, EOG, EMG) of six normal pointer dogs were recorded in a laboratory setting. Two states of sleep (slow-wave and rapid eye movement) and wakefulness (alert and drowsy) were identified. The total recording period comprised 44% of alert wakefulness, 21% of the drowsy state, while slow-wave sleep occupied 23% and REM sleep 12% of the time. The mean length of a REM sleep episode averaged 6 min and the mean REM sleep cycle was 20 min. The mean polycyclic sleep-wake cycle was 83 min. Sleep episodes averaged 45 min and the mean waking episode was 38 min. There was an average of two REM sleep episodes per sleep-wake cycle. The dog has a propensity to sleep over a 16-hr interval from 1300 to 0500 but the most sleep occurred between 2100 and 0400 hr during darkness.

Animals↗
PubMed1976

The bony tentorium of the cat: stereotaxic coordinates.

The cat's tentorium cerebelli is an osseous structure which overlies much of the brain stem. None of the current brain atlases list the coordinates of this bony projection. With a stiff wire and a stereotaxic apparatus, the location of its free edge and dorsal surface was mapped in 1.0 mm steps in the skulls of 16 cats. In the midline the dorsal surface meets the calvaria at a point 7 mm posterior and 15 mm superior to the atlas zero (intra-aural plane + 10 mm horizontal). From this junction it slopes inferiorly and anteriorly between the cerebrum and cerebellum along a 50 degree slope to terminate along a curved line. In the midline this free edge is located 0.5 mm anterior, and 6.5 mm superior to the atlas zero. It recedes laterally along a curved line to a point 6 mm lateral, 6 mm superior and 3 mm posterior to the atlas zero. The free edge then curves forward and descends to pass through an imaginary line 3 mm anterior and 4.5 mm inferior to the altas zero. Statistical comparisons between measurements made in male and female cats revealed no significant differences.

Animals↗