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Biomedical subjects

W Dement

Publications and source records attributed to W Dement.

At least 19 recordsLinked to original sources
PubMed1998

The Taskforce 2000 survey on medical education in sleep and sleep disorders.

Previous research has shown evidence of a widening gap between scientific research and clinical teaching in sleep and sleep disorders. To address the deficiencies in current medical education in sleep, the Taskforce 2000 was established by the American Sleep Disorders Association. The present study was undertaken to assess the teaching activities, needs and interests of the membership of the two largest professional sleep societies (American Sleep Disorders Association and Sleep Research Society). Survey instruments included a brief, 5-item postcard survey, which was mailed to all members, followed by an in-depth, 34-item questionnaire, which was completed by 158 respondents from the intitial postcard survey (N = 808). Results indicated that the majority of respondents (65.2%) are currently involved in teaching sleep to medical students or postgraduate trainees, although the average amount of teaching time was only 2.1 hours for undergraduate and 4.8 hours for graduate education in sleep. Teaching of sleep laboratory procedures and clinical evaluation of sleep-disordered patients is limited at either an undergraduate or postgraduate level. The major deficiencies noted were the lack of time in the medical curriculum and the need for better resources and teaching facilities. A large majority of respondents indicated their willingness to be involved in sleep education for physicians, and rated this a high priority for the professional organization.

Curriculum↗
PubMed1991

Radioligand binding to adenosine receptors and adenosine uptake sites in different brain regions of normal and narcoleptic dogs.

The present study compares the characteristics of radioligand binding to adenosine receptors and adenosine uptake sites in 100- and 50-day-old normal and narcoleptic dogs. Binding to A1 receptors was quantified using a selective A1 agonist ([3H]N6-[(R)-1-methyl-2-phenylethyl] adenosine, [3H]R-PIA) and an antagonist ([3H]dipropyl-8-cyclopentyl-xanthine, [3H]CPX). Differences in the binding of [3H]R-PIA and that of [3H]5'-ethylcarboxamide adenosine ([3H]NECA), which binds to both A1 and A2 receptors with similar affinities, were used to quantify A2 receptors. Nucleoside transport sites were labeled with [3H]nitrobenzylthioinosine ([3H]NBTI), a potent inhibitor of nucleoside transport systems. The present study offered no evidence that either adenosine A1 receptors and adenosine uptake sites in the frontal cortex or adenosine A2 receptors in the putamen were altered in narcoleptic dogs. However, we found that adenosine A1 receptors in the dog exist in different affinity states and that the affinity state in which the receptor is found depends on the brain region examined. A characterization of these low- and high-affinity sites was performed and results indicated that these sites cannot be explained by a single interaction of the A1 receptor with a single G-protein population.

Adenosine↗
PubMed1989

Evidence for multiple [3H]prazosin binding sites in canine brain membranes.

Two classes of alpha 1 adrenoceptors were identified in canine brain and liver using conventional radioligand binding methods. Scatchard plots of specific [3H]prazosin binding to brain and liver membranes prepared from 100-150-day-old Doberman pinscher dogs were consistently curvilinear and best fit a two-site binding model (frontal cortex, Kd1 = 57.7 +/- 10.0 pM, Bmax1 = 64.6 +/- 17.1 fmol/mg protein, Kd2 = 1.5 +/- 0.5 nM, Bmax2 = 159 +/- 37.6 fmol/mg protein; liver, Kd1 = 82.6 +/- 36 pM, Bmax1 = 7.0 +/- 5.1 fmol/mg protein, Kd2 = 0.8 +/- 0.2 nM, Bmax2 = 62.1 +/- 8.7 fmol/mg protein). Kinetically derived affinity constants from association and dissociation experiments agreed with those obtained by Scatchard analyses of equilibrium binding data. Binding sites were saturable, heat labile, bound ligand reversibly, and appeared to be appropriately distributed in relation to endogenous catecholamine. [3H]Prazosin also bound with high affinity to two classes of binding site in porcine and bovine brain membrane but [3H]prazosin binding in monkey and rat brain was best described by a single-site binding model. Affinities obtained were in between values obtained for high and low affinity Kds in the other species. Competitions for [3H]prazosin binding sites in canine frontal cortex were conducted with the following antagonists: WB-4101, corynanthine, phentolamine, benoxathian, phenoxybenzamine, chlorethylclonidine, thymoxamine, prazosin, yohimbine and agonists: methoxamine, (-)-norepinephrine, and clonidine. All ligands but prazosin, norepinephrine and clonidine competed for specific [3H]prazosin binding in a statistically significant biphasic manner. Benoxathian and WB-4101 displayed the highest affinities (benoxathian: Ki1 = 0.26 nM, WB-4101: Ki1 = 0.20 nM) and selectivity (high affinity/low affinity: benoxathian = 1640, WB-4101 = 13204) for the high affinity [3H]prazosin binding site; chlorethylclonidine had highest affinity (Ki2 = 91 nM) and selectivity (low affinity/high affinity = 405) for the lower affinity [3H]prazosin binding site. As defined, the two sites were similar to the alpha 1a and alpha 1b recently described in the rat and rabbit. A noticeable difference was that the subtypes described in dog brain had a 30-fold difference in affinity for prazosin.

Animals↗
PubMed1987

The assessment of a new technology for evaluating respiratory abnormalities in sleep.

This study assessed the diagnostic utility of two technologies for evaluating respiratory abnormalities in sleep. We compared conventional polysomnography with a new, ambulatory microprocessor technology. Two key features of the comparison involved: (a) the use of multiple, skilled interpreters of each system; and (b) inter-rater agreement within the systems as a crucial test for the diagnostic utility of each. Results indicated that general categories of respiratory abnormalities could be judged more reliably than more specific categories, regardless of technology. For certain categories of respiratory abnormalities, however, inter-rater agreement with the newer technology was extremely low (e.g., reliability coefficients of .12, .09, and -0.6). Factors contributing to these low diagnostic reliabilities are discussed. Our data indicate that any assessment of new technology cannot be made apart from the clinical judgments to be rendered with that new technology. This approach may be generalizable to the assessment of other diagnostic technologies.

Diagnosis, Computer-Assisted↗
PubMed1985

Periodic leg movements during sleep in the elderly.

Periodic leg movements in sleep (PLMS) occur frequently in the sleep of elderly persons but their significance is unknown. In this study, 63 elderly persons with symptoms of insomnia but without history of renal disease were evaluated polysomnographically. All received laboratory evaluations for blood urea nitrogen (BUN) and creatinine and completed a questionnaire on sleep complaints. Results indicated a positive relationship between PLMS and urea nitrogen in elderly women. In addition, symptoms of leg twitching and prolonged sleep latency could distinguish arbitrarily formed high and low PLMS groups. These results suggest that PLMS could be a window on the age-related decline in renal function and that these movements are related to several highly specific symptoms of geriatric insomnia.

Aged↗
PubMed1985

Preliminary communication: intellectual deficit and sleep-related respiratory disturbance in the elderly.

Polysomnography and neuropsychological tests administered to 41 nondemented male subjects (mean age, 69.5) indicated that impaired performance was associated with sleep-related respiratory disturbance. Such deficits could reflect deficits in vigilance or cortical insult resulting from nightly hypoxemia. Whether the degree of impairment observed here predicts more severe dementia will await longitudinal studies.

Aged↗
PubMed1984

Issues in the diagnosis and treatment of insomnia.

Most people attribute a restorative function to sleep. This is because experimental or clinical sleep disturbance is usually followed by annoying symptoms of fatigue and sleepiness the following day. Can these daytime changes be documented objectively? In the past several years, the Multiple Sleep Latency Test (MSLT) has been developed and validated as an objective quantitative measure of sleepiness. Multiple assessments of sleep latency yield a profile of sleepiness across the day. This profile changes in the predicted direction with acute total and partial sleep deprivation, chronic sleep deprivation, sleep satiation, and in comparisons between hypersomnia patients and controls. Sleep and wakefulness are complementary phases in the daily cycle of human existence. Adequacy of sleep and energetic wakefulness next day are interacting phases in this cycle. Insomnia can be seen as a perception of disturbed sleep with daytime consequences, but is essentially also a symptom. This paper reviews a number of issues in the diagnosis and treatment of insomnia. The dimensions, daytime consequences and longitudinal aspects of insomnia are considered. Most investigations to date have been geared towards the problem of chronic insomnia and yet we are all likely to suffer from transient insomnia at some point. Psychiatric and psychophysiological disorders have been shown to be the most frequent causes of disorders of initiating and maintaining sleep. Moreover, there is an apparent disparity between subjective and objective sleep parameters with, for example, objectively disturbed sleep in noncomplaining subjects. The criteria of hypnotic efficacy and the effects of triazolam and flurazepam on sleep and daytime alertness have been investigated in normals, chronic insomniacs and the elderly. In general, chronic insomniacs showed all degrees of daytime alertness regardless of nocturnal sleep parameters. About one-third could be classified as fully alert all day long in spite of their complaints. The effect of flurazepam and triazolam on sleep (improvement) was essentially the same. Daytime effects were most closely related to half-life. The long-acting benzodiazepine, flurazepam, impaired daytime alertness although nocturnal sleep was improved. Triazolam improved not only nighttime sleep but also daytime alertness.

Chronic Disease↗
PubMed1984

Measurement error in visually scored electrophysiological data: respiration during sleep.

Electrophysiological sleep studies employ the simultaneous recording of multiple physiological parameters. These data are often scored and analyzed visually, i.e. by trained human scorers. In this study, we investigated the measurement error inherent in visual evaluation of respiratory disturbances during human sleep. Three trained scorers independently evaluated twenty-eight all-night sleep recordings. Results indicated that the scorers achieved high agreement on only selected variables. Scorers' experience did not affect the reliability and independent judgements of recording quality did not account for the discrepancies. These findings, although most relevant for the specific parameters studied here, as well as for these scoring criteria, subjects, and techniques, document the unreliability of certain visually scored sleep data. The present paradigm may be useful in evaluating other types of measurement error.

Aged↗
PubMed1984

Longitudinal development of sleep-related respiratory disturbance in adult humans.

A number of cross-sectional studies have found that sleep-related respiratory disturbance ( SRRD ) is common in elderly adults. This preliminary study reports on samples of middle-aged and elderly humans in good health whose polysomnographically recorded sleep was followed over time. Participants were selected for low levels of SRRD on Time 1 recording. Results indicated an increase in SRRD over the study period. This increase ws not limited to rapid eye movement or nonrapid eye movement sleep; tobacco usage, medication status, and weight gain could not account for the change, although in several cases, modest weight gain was associated with increased respiratory disturbance. These data imply that future studies of incidence of SRRD may reveal changes within a 10-year period, although the pathological consequences of these age-related changes, if any at all, may take a longer period to develop.

Aged↗
PubMed1984

Nighttime and daytime efficacy of flurazepam and oxazepam in chronic insomnia.

Trials of hypnotic medications typically determine efficacy by examining changes in polysomnographically recorded sleep and in daytime performance. The authors employed daytime sleepiness as a new, potentially crucial criterion in such trials. Oxazepam and flurazepam were effective in improving some polysomnographically defined measures of nocturnal sleep in 14 patients with chronic insomnia; flurazepam produced substantial daytime sleepiness and oxazepam did not. Oxazepam produced some rebound insomnia, consisting of about an hour's reduction of polysomnographically defined sleep, but without gross mood disturbance or the patients' awareness of sleep loss.

Chronic Disease↗
PubMed1983

Daytime sleepiness as a criterion in hypnotic medication trials: comparison of triazolam and flurazepam.

Sleep laboratory hypnotic medication trials typically determine efficacy by examining changes in polysomnographically recorded sleep. We introduce the use of daytime sleepiness, as assessed by the Multiple Sleep Latency Test (MSLT), as a criterion for daytime functioning in such trials. Two benzodiazepine hypnotics, triazolam (0.5 mg) and flurazepam (30 mg), with short and long half-lives respectively, were compared in a multicentered, double-blind crossover study. Results indicated these medications had virtually indistinguishable nocturnal effects, but differed dramatically during the day. Flurazepam decreased sleep latency on the MSLT, whereas triazolam did not. These results could indicate that daytime sleepiness is a concomitant effect of flurazepam.

Adult↗
PubMed1981

Delayed sleep phase syndrome. A chronobiological disorder with sleep-onset insomnia.

We describe a new syndrome called "delayed sleep phase insomnia." Thirty of 450 patients seen for a primary insomniac complaint had the following characteristics: (1) chronic inability to fall asleep at a desired clock time; (2) when not on a strict schedule, the patients have a normal sleep pattern and after a sleep of normal length awaken spontaneously and feel refreshed; and (3) a long history of unsuccessful attempts to treat the problem. These patients were younger than the general insomniac population and as a group did not have a specific psychiatric disorder. Six patients' histories are described in detail, including the successful nonpharmacological chronotherapy regimen (resetting the patients' biological clock by progressive phase delay). Delayed sleep phase insomnia is proposed to be a disorder of the circadian sleep-wake rhythm in which the "advance" portion of the phase response curve is small.

Adolescent↗
PubMed1977

Neuronal activity specific to REM sleep and its relationship to breathing.

The search for the neural substrate of a state of consciousness has led to the expectation that there may be neurons which discharge tonically and rhythmically during that state alone. We have now recorded in the cat the first evidence of neurons whose rhythmic discharge is consistent with the hypothesis of a tonically active neural substrate for rapid eye movement (REM) sleep. These neurons, located in the area of gigantocellular and lateral medullary tegmental fields, begin rhythmically discharging simultaneously with the cortical desynchronization at REM sleep onset and cease firing at arousal from REM; they are essentially silent at all other times. Modulations of the discharge rate correlate with the phasic events of REM sleep, such as ataxic breathing and eye movement bursts. In addition, there is a high correlation between their discharge rate and respiratory frequency analyzed on a breath-by-breath basis. The significant rhythmicity of their discharge coupled with high REM selectivity contrasts them with putative REM generators reported by others in the pons and suggests their crucial role in REM generation.

Action Potentials↗
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↗
PubMed1976

Evaluation of short-term and long-term treatment of the narcolepsy syndrome with clomipramine hydrochloride.

Clinical examinations, questionnaires, and 24- or 36-hour polygraphic recordings were performed on 21 adult patients with the narcolepsy syndrome to investigate the short- and long-term effects of clomipramine HCL. Cataplexy was improved by the medication, but tolerance was observed 4 1/2 months of treatment. Clomipramine HCL induced significant changes in the sleep EEG, chin EMG, and EOG. In two patients, clomipramine HCL caused a nocturnal myoclonia that produced insomnia. Sexual side effects were seen with clomipramine HCL, particularly in males. A combination of clomipramine HCL and L-Dopa apparently prevented this difficulty in one patient. A rebound of cataplexy was seen during the 15 days following withdrawal of the drug. Methysergide maleate was found to be ineffective on cataplexy in four patients.

Adult↗
PubMed1975

[Can an anomaly of the central nervous system be responsible for hemodynamic disorders].

Twenty-seven subjects with insomnia or diurnal hypersomnolence presented a sleep apnea syndrome when their respiration was systematically checked during sleep. These sleep-induced respiratory abnormalities were completely occult and pulmonary function tests performed during wakefulness were normal. The patients, all non-obese, presented serious pulmonary artery pressure changes which were directly connected with the repetitive sleep apneas. Half of the patients also had systemic hypertension. Two children (aged 11 and 15) underwent tracheostomies which by-passed the sleep-induced obstruction. Systemic hypertension was reduced after surgery.

Adolescent↗