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Biomedical subjects

W C Orr

Publications and source records attributed to W C Orr.

At least 109 records · Page 6Linked to original sources
PubMed1985

Effect of sleep state and position on the incidence of obstructive and central apnea in infants.

Sixty-four infants with a history of apnea were studied to determine the effects of sleeping position and sleep state (rapid eye movement [REM]) v (non-rapid eye movement [NREM]) on the occurrence of central and obstructive apneas. All-night polysomnographic studies were conducted on each infant, and the spontaneous occurrence of central and obstructive apneic events was determined in the prone, supine, and side positions. Sleeping position did not significantly affect the rate or duration of central or obstructive apneas. Furthermore, neither central nor obstructive apneic episodes were significantly altered by sleep state. These data suggest that, in spite of an ostensible predisposition to upper airway obstruction in the supine position and during rapid eye movement sleep, neither sleeping position nor sleep state appears to affect the rate of duration of apneic events.

Age Factors↗
PubMed1985

The effects of swallowing frequency and transdermal scopolamine on esophageal acid clearance.

Fourteen volunteers were studied on two occasions to assess the effect of swallowing frequency on acid clearance time. The experimental protocol consisted of two trials of infusion of 15 ml of 0.1 N HCl into the distal esophagus. One trial required swallowing every 30 s for 10 min. The other trial involved an initial rapid swallowing rate (seven swallows in the 1st min) with a gradual predetermined decline in rate. This procedure was repeated 12 h after application of a transdermal scopolamine patch. Baseline clearance times for rapid and slow swallowing were not significantly different. The anticholinergic drug significantly prolonged the clearance times for both rapid and slow swallowing. Under baseline conditions, sequential swallows (after the first three to four swallows) produced a significant rise in pH until the clearance criterion of pH 4.0 was reached. This effect was abolished with the anticholinergic drug. These results support a two-stage model of acid clearance with initial volume clearance and subsequent salivary buffering of residual intraesophageal acid.

Administration, Topical↗
PubMed1984

Nonhypersomnolent patients with obstructive sleep apnea.

Until recently, snoring had been considered both a medical enigma and a psychosocial problem. Snoring is now considered to be an acoustic phenomenon produced by vibration of the soft palate and the tonsillar pillars. We describe 20 patients with a clinical complaint of excessive snoring who were referred to rule out obstructive sleep apnea. All patients were without symptoms of daytime sleepiness and failure of the right heart. Twenty subjects were studied, 18 of whom were males. All subjects were monitored for one full night in the Sleep Laboratory. The apnea rate ranged from 9.0 to 94.0 incidents an hour with a mean of 30.0. Eight of the 20 subjects had obstructive episodes longer than 1 minute and three others had episodes longer than 55 seconds. Hypersomnolence, long thought to be a cardinal symptom, is not present in all patients with an ostensibly significant degree of obstructive sleep apnea.

Adult↗
PubMed1984

Effect of sleep on swallowing, esophageal peristalsis, and acid clearance.

Recent studies have shown that impaired esophageal clearance of refluxed material during the sleeping interval plays a major role in the pathogenesis of esophagitis. The present investigation compares esophageal responses to both acid and water infusions during sleep in asymptomatic subjects. Fourteen healthy individuals were studied. The subjects were studied for two nights in the sleep laboratory. Each night involved four to six infusions of 15 ml of either sterile water or 0.1 N HCl. A similar infusion was conducted during the presleep waking interval. Acid clearance time was shown to decrease as a function of increasing wakefulness during the acid clearing interval. Arousal responses were significantly greater with acid infusions during sleep (p less than 0.05). Awakenings from sleep with acid infusions were associated with significantly greater swallowing rates than those associated with water infusions (p less than 0.01). Peristaltic parameters of amplitude, velocity, and duration were not differentially affected by acid versus water infusions or by sleep versus waking.

Adult↗
PubMed1983

Postprandial sleepiness: objective documentation via polysomnography.

Fifteen normal volunteers were evaluated to assess the effect of a meal on sleep onset latency. The meal was administered in a counterbalanced design on 1 of 2 successive days. Subjects napped 20 min subsequent to the meal (or at the corresponding time on the no-meal day) and 1 h after the initiation of the first nap. Ten subjects completed the Stanford Sleepiness Scale (SSS) on arriving at the laboratory, and just prior to nap 1 and nap 2. Sleep onset latency after the meal was not significantly different from that obtained under the no-meal condition, but was significantly less on nap 1 as compared with nap 2 irrespective of day or meal. SSS did not reveal subjective differences in sleepiness between the initial estimate and the postmeal estimate. Only five subjects showed a decrease in sleep onset latency postprandially (1-11 min). Although group differences in postprandial sleepiness were not documented, the phenomenon was clearly exhibited by certain individuals. Thus, postprandial sleepiness is not an invariable consequence of meal ingestion; rather, it appears to be affected by numerous variables such as hunger, volume of the meal, and meal constituents.

Adult↗
PubMed1982

Clustering of spore-specific genes in Aspergillus nidulans.

We have investigated the chromosomal organization of genes that are expressed specifically in the asexual spores (conidia) of the Ascomycete fungus Aspergillus nidulans, using two experimental approaches. In the first, 30 different recombinant clones, containing long nuclear DNA inserts and at least one spore-specific gene, were selected randomly. The total number of spore-specific genes present in each clone was then determined by RNA blot analysis. In the second approach, several chromosomal recombinant DNA libraries, having average insert lengths ranging from 1 to 15 kilobases, were constructed. The fraction of clones in each library having one or more spore-specific poly(A)+RNA-coding regions was then determined by colony or plaque filter hybridization with radiolabeled, spore-specific, complementary DNA. The results from these experiments were compared to statistical predictions based on the assumption that the spore-specific genes are randomly distributed in the Aspergillus genome. In both cases, the experimental values deviated significantly from the predicted values, demonstrating that the spore-specific genes are nonrandomly arranged in the genome. Rather, they appear frequently to occur in tightly linked clusters.

Aspergillus nidulans↗
PubMed1982

Sleep and dreaming disturbances in closed head injury patients.

Single night sleep recordings in closed head injury patients 6 to 59 months after injury revealed less stage 1 and a greater number of awakenings compared to age matched controls. Neither the time spent in REM sleep nor the Wechsler Memory Quotient were related to complaints of decreased or absent dreaming following injury. The proportion of REM and number of awakenings, however, showed a moderate relationship to certain behavioural problems.

Adolescent↗
PubMed1982

Hypertensive peristalsis in the pathogenesis of chest pain: further exploration of the "nutcracker" esophagus.

The recently described "nutcracker esophagus" is associated with hypertensive peristaltic contractions and clinical complaints of chest pain and/or dysphagia. This report describes our experience with a group of 28 patients meeting the manometric and clinical criteria for this esophageal motor disorder, and it includes a specific comparison of contractions in the proximal and distal esophagus. Mean lower esophageal sphincter pressure, peak peristaltic pressures, mean peristaltic pressures, and contraction durations were all significantly elevated in the patient group. Using similarly radially oriented transducers, the amplitudes of peristaltic contractions in the distal esophagus were shown to be significantly greater in the patients than in an asymptomatic control group. No significant peristaltic differences were found between patients and controls in the proximal esophagus. These data support the existence of nutcracker esophagus as an identifiable esophageal motor disorder with several specific divergences from esophageal peristaltic parameters in controls.

Adult↗
PubMed1981

Acid clearance during sleep in the pathogenesis of reflux esophagitis.

Impaired esophageal clearing of refluxed gastric contents during sleep has been implicated in the pathogenesis of reflux esophagitis. To more directly evaluate this hypothesis, 13 symptomatic patients with esophagitis and 13 normal controls had 15 ml of 0.1 N HCl instilled into the esophagus in the recumbent position while awake and during polygraphically monitored sleep. When sleep was maintained for the majority of the acid-clearing duration, the clearance times for both patients and controls were significantly prolonged when compared to those while awake (P less than 0.01). However, when sleep was maintained for less than 50% of the acid-clearing interval, the patients showed significantly longer acid clearance times. The swallowing rate did not differentiate the two groups under any condition. These data show that sleep impairs esophageal acid clearance. Acid clearance occurred predominantly in association with arousals from sleep. The defective acid clearance found in patients with esophagitis probably plays a major role in the pathogenesis of this disorder.

Adult↗
PubMed1981

Myxedema and obstructive sleep apnea.

Three cases of hypersomnolence, snoring and documented sleep apnea are reported. All three patients were profoundly myxedematous, both clinically and biochemically. Polygraphic studies during sleep documented the presence of repetitive episodes of obstructive sleep apnea in all three patients. These were accompanied by arterial oxygen desaturation. After becoming euthyroid following the administration of the l-thyroxine all patients underwent a repeat evaluation in the sleep laboratory. These studies revealed nearly complete resolution of obstructive sleep apnea in all patients. In addition, several sleep parameters showed marked improvement. These data strongly suggest that the presence of profound daytime sleepiness in hypothyroid patients could be indicative of a potentially lethal complication of myxedema, obstructive sleep apnea.

Cholesterol↗
PubMed1981

Obstructive sleep apnea associated with tonsillar hypertrophy in adults.

Six adults with tonsillar enlargement were shown via all-night polygraphic recordings to have varying degrees of upper airway obstruction during sleep. All but one of these patients were noted to have profound and debilitating daytime sleepiness. All patients had extremely loud snoring with anecdotal reports of apnea. Postoperatively all patients reported a marked reduction in snoring and substantial improvement in their daytime sleepiness. Postoperative sleep laboratory evaluation in four cases revealed nearly complete obliteration of upper airway obstruction and improvement in several objective sleep measurements, such as sleep-onset latency. We conclude that even relatively mild tonsillar enlargement can play an important role in the pathogenesis of obstructive sleep apnea.

Adolescent↗
PubMed1980

Molecular cloning and selection of genes regulated in Aspergillus development.

Over 350 clones homologous to poly(A)+ RNAs that are significantly more prevalent in conidiating cultures of Aspergillus nidulans than in somatic cells have been selected from a recombinant DNA library formed between nuclear DNA and lambda Charon 4A. The procedure used for this selection involved in situ hybridization to a cDNA probe which had been selectively depleted of sequences represented in somatic cells by complement hybridization. Five of these clones have been characterized further. All but one encoded poly(A)+ RNAs that were at least ten times more prevalent in conidiating cultures than in somatic cells. One clone hybridized to a single, developmentally regulated RNA. The three others were complementary to several RNAs having different molecular weights, each of which was more prevalent in condiating cultures than in vegetative cells. These results and quantitative aspects of the selection procedure suggest that developmentally controlled poly(A)+ RNA coding regions may not be distributed randomly in the Aspergillus genome.

Aspergillus nidulans↗