Sleep organization and regulation

Sleep is a vital, complex state with as yet unknown functions. It is active and highly organized and is regulated by homeostatic, circadian, and ultradian processes. It consists of two distinct sleep states, rapid eye movement (REM) and non-rapid eye movement (NREM), both of which have a dramatic impact on many aspects of physiology and behavior. The significance and consequences of the REM-NREM organization of sleep are not known. On the other hand, the sleep state and its organization are quite fragile and dynamic. Any number of factors can disrupt sleep and its expression, and its nature changes over the life span. What is certain is that any reduction and/or disruption of sleep hinders an organism's ability to navigate through the waking state.

Effects of sleep deprivation on daytime sleepiness in primary insomnia

STUDY OBJECTIVES

This study investigated changes in MSLT scores and recovery sleep following total sleep deprivation in subjects with insomnia as compared to normal sleepers.

DESIGN

Matched-groups design.

SETTING

A sleep disorders center in a large medical center.

PARTICIPANTS

Ten individuals with psychophysiological insomnia and ten age- and sex-matched normal sleepers served as subjects.

INTERVENTIONS

Subjects underwent total sleep deprivation after baseline polysomnography and MSLT. A post-deprivation MSLT was obtained, as well as polysomnography on the recovery night and an MSLT after the recovery night.

MEASUREMENTS AND RESULTS

Both groups showed significant decreases in MSLT scores following total sleep deprivation, as compared to baseline. Both groups had significantly shorter scores on a nighttime MSLT compared to a daytime MSLT. The insomnia group also showed a significant increase in total sleep time on the recovery night compared to baseline.

CONCLUSIONS

The MSLT is sensitive to changes in sleepiness associated with total sleep deprivation in individuals with primary insomnia.

A human REV7 homolog that interacts with the polymerase zeta catalytic subunit hREV3 and the spindle assembly checkpoint protein hMAD2

Widespread alteration of the genomic DNA is a hallmark of tumors, and alteration of genes involved in DNA maintenance have been shown to contribute to the tumorigenic process. The DNA polymerase zeta of Saccharomyces cerevisiae is required for error-prone repair following DNA damage and consists of a complex between three proteins, scRev1, scRev3, and scRev7. Here we describe a candidate human homolog of S. cerevisiae Rev7 (hREV7), which was identified in a yeast two-hybrid screen using the human homolog of S. cerevisiae Rev3 (hREV3). The hREV7 gene product displays 23% identity and 53% similarity with scREV7, as well as 23% identity and 54% similarity with the human mitotic checkpoint protein hMAD2. hREV7 is located on human chromosome 1p36 in a region of high loss of heterozygosity in human tumors, although no alterations of hREV3 or hREV7 were found in primary human tumors or human tumor cell lines. The interaction domain between hREV3 and hREV7 was determined and suggests that hREV7 probably functions with hREV3 in the human DNA polymerase zeta complex. In addition, we have identified an interaction between hREV7 and hMAD2 but not hMAD1. While overexpression of hREV7 does not lead to cell cycle arrest, we entertain the possibility that it may act as an adapter between DNA repair and the spindle assembly checkpoint.

New trends in insomnia management

Pharmacological management of insomnia is continually evolving. The introduction of non-benzodiazepine benzodiazepine receptor agonist hypnotics provides an opportunity to understand different patterns of pharmacological activity with mechanistic differences in receptor activity. The impact of insomnia on daytime functioning and long-term health and socioeconomic status has been recognized. Epidemiological studies indicate that insomnia is associated with increased absenteeism and healthcare costs (although the latter appear to be partly attributable to comorbid depression). It will thus be important to determine whether hypnotics, in addition to their effects on sleep, provide other benefits for the patient that are related to these parameters. The successful resolution of this issue will require the adoption of additional outcome measures, such as effects on quality of life and healthcare costs. Recognition that long-term hypnotic use is widespread among insomniacs has prompted proposals for alternative prescribing patterns. Although certain hypnotics appear to be free of tolerance on prolonged use, caution is required in the long-term use of any hypnotic because of the lack of systematic data on chronic efficacy and safety. Therefore, alternative administration schedules (e.g. intermittent and 'as required') are being investigated. These may have very different consequences in terms of abuse liability and patients' perceptions of efficacy, and thus permit a more effective and appropriate use of this drug class.

Effects of an experimentally induced rhinovirus cold on sleep, performance, and daytime alertness

STUDY OBJECTIVES

There is accumulating evidence that the common cold produces impairments in psychomotor vigilance. This has led some investigators to hypothesize that such illnesses may also have disruptive effects on sleep. While several self-report studies suggest that viral illness may influence sleep parameters, no studies have assessed polysomnographically recorded sleep following viral infections.

DESIGN

Parallel control group comparison.

SETTING

Sleep laboratory in a large urban medical center.

PARTICIPANTS

Twenty-one men and women with susceptibility to the rhinovirus type 23.

INTERVENTIONS

Nasal inoculation with rhinovirus type 23.

MEASUREMENTS

Polysomnographically recorded sleep for five nights (2300-0700 h) post-viral inoculation. Twice daily (1030 and 1430 h) performance assessment during each experimental day using auditory vigilance and divided attention tasks. A multiple sleep latency test (MSLT) was performed daily for the duration of the study.

RESULTS

In symptomatic individuals, total sleep time decreased an average of 23 min, consolidated sleep decreased an average of 36 min, and sleep efficiency was reduced by an average of 5% during the active viral period (experimental days/nights 3-5) compared with the incubation period. Psychomotor performance was impaired. These changes were significantly greater than those observed in asymptomatic individuals.

CONCLUSIONS

The common cold can have detrimental effects on sleep and psychomotor performance in symptomatic individuals during the initial active phase of the illness.

Acid-sensitive polyethylene glycol conjugates of doxorubicin: preparation, in vitro efficacy and intracellular distribution

Coupling anticancer drugs to synthetic polymers is a promising approach of enhancing the antitumor efficacy and reducing the side-effects of these agents. Doxorubicin maleimide derivatives containing an amide or acid-sensitive hydrazone linker were therefore coupled to alpha-methoxy-poly(ethylene glycol)-thiopropionic acid amide (MW 20000 Da), alpha,omega-bis-thiopropionic acid amide poly(ethylene glycol) (MW 20000 Da) or alpha-tert-butoxy-poly(ethylene glycol)-thiopropionic acid amide (MW 70000 Da) and the resulting polyethylene glycol (PEG) conjugates isolated through size-exclusion chromatography. The polymer drug derivatives were designed as to release doxorubicin inside the tumor cell by acid-cleavage of the hydrazone bond after uptake of the conjugate by endocytosis. The acid-sensitive PEG conjugates containing the carboxylic hydrazone bonds exhibited in vitro activity against human BXF T24 bladder carcinoma and LXFL 529L lung cancer cells with IC70 values in the range 0.02-1.5 microm (cell culture assay: propidium iodide fluorescence or colony forming assay). In contrast, PEG doxorubicin conjugates containing an amide bond between the drug and the polymer showed no in vitro activity. Fluorescence microscopy studies in LXFL 529 lung cancer cells revealed that free doxorubicin accumulates in the cell nucleus whereas doxorubicin of the acid-sensitive PEG doxorubicin conjugates is primarily localized in the cytoplasm. Nevertheless, the acid-sensitive PEG doxorubicin conjugates retain their ability to bind to calf thymus DNA as shown by fluorescence and visible spectroscopy studies. Results regarding the effect of an acid-sensitive PEG conjugate of molecular weight 20000 in the chorioallantoic membrane (CAM) assay indicate that this conjugate is significantly less embryotoxic than free doxorubicin although antiangiogenic effects were not observed.

Repeated nocturnal sleep latencies in narcoleptic, sleepy and alert subjects

OBJECTIVES

The purpose of this study was to assess nocturnal sleep latencies among narcoleptics.

METHODS

Thirteen narcoleptics and matched sleepy and alert controls participated in this study. Subjects were awakened three times on each of two experimental nights. The latencies to sleep and rapid eye movement sleep were evaluated at the beginning of the night and following each experimental awakening.

RESULTS

The alert group (AG) had a significantly longer mean nocturnal sleep latency than the narcoleptic (NG) and sleepy groups (SG). The sleep latencies at 23:00 and 01:10 h were significantly longer than the latencies at 03:10 and 05:10 h. The interaction between group and time of night demonstrated longer latencies at 23:00 and 03:10 h for the AG when compared to the SG and the NG. At 01:10 and 05:10 h all groups had comparable latencies. The number of subjects in the NG who had multiple sleep onset REM periods (SOREMPs) was significantly higher than in either the AG or the SG.

CONCLUSIONS

Narcoleptics were found to have a heightened propensity to fall asleep and increased number of SOREMPs during nocturnal sleep opportunities. These characteristics are consistent with the daytime polysomnographic findings known in this patient population.

Sleepiness and the reinforcing and subjective effects of methylphenidate

On 4 days, 6 volunteers received 10 mg methylphenidate or placebo at 0900 after 4 or 8 hr time in bed (TIB) and then on 4 days after 4 or 8 hr TIB chose their preferred capsule. On sampling days, 4 hr TIB increased multiple sleep latency test (MSLT) scores and Fatigue scale scores on the Profile of Mood States (POMS). In both TIBs, the drug increased the MSLT and POMS Vigor and Tension scale scores. It reduced POMS Fatigue scores and improved divided attention performance to a greater extent after 4 versus 8 hr. Drug was chosen on 88% of days after 4 hr, but only 29% of days after 8 hr. Preference for the drug depends on sleepiness and is mediated by performance-enhancing and fatigue-altering effects.

[Giant diverticula of the colon. Apropos of 2 cases]

Giant diverticulum of the colon is a rare complication of the colonic diverticulosis. It generally involves the sigmoid colon. In the chronic form, without symptoms or with only a few non-specific symptoms, an abdominal mass is frequently palpable. A plain abdominal radiogram, showing a gas-filled cyst, can suggest the diagnosis. If needed, an abdominal CT scan is appropriate and seems to be more accurate than a barium enema. The treatment of choice is a segmental resection of the colon involving the giant diverticulum, followed by a direct anastomosis. Despite the old age of these patients, both postoperative morbidity and mortality are low and justify such a radical approach. The acute clinical presentation (about 20%) is generally due to a peritonitis by perforation of the giant diverticulum and requires an emergency colectomy.

Characteristics of insomnia in the United States: results of the 1991 National Sleep Foundation Survey. I

The National Sleep Foundation in conjunction with the Gallup Organization conducted telephone interviews with a sample of Americans (N = 1000) to examine the prevalence and nature of difficulty with sleep. Consistent with other national studies, about one-third of Americans reported some type of sleep problem. Approximately one in four reported occasional insomnia while 9% reported that their sleep difficulty occurred on a regular nightly basis. The problem most frequently reported by insomniacs was waking up in the morning feeling drowsy or tired, followed by waking up in the middle of the night, difficulty going back to sleep after waking up and difficulty falling asleep initially. Importantly, insomniacs rarely visited a physician to discuss their sleep problem and four out of ten insomniacs self-medicated with either over-the-counter medications or with alcohol. Two-thirds of the insomniacs reported that they did not have an understanding of available treatments for insomnia.

Reduction of fibronectin expression by intravitreal administration of antisense oligonucleotides

We have investigated whether antisense oligonucleotides delivered intravitreally could reduce gene expression specifically in the retina. In this study, phosphorothioate antisense oligonucleotides targeted to fibronectin transcripts were coupled to a novel carrier and used to specifically reduce fibronectin (FN) expression in retinal vascular cells. Using confocal microscopy, fluorescence from fluorescein isothio-cyanate-labeled FN-oligonucleotides was detected in retinal vascular cells at 24 h postinjection and persisted until day 6 (the end point of this study). The fibronectin mRNA level was consistently decreased to 86.7% +/- 7.9% of control (p<0.05) at day 2, and 46.7% +/- 4.9% of control (p<0.01) at day 6. In contrast, the beta-actin mRNA level, an internal control, was unaltered in rat retinas that received FN-oligonucleotides. Fibronectin protein level at day 6 was also significantly reduced to 61.4% +/- 16% of control (p<0.01). No toxic effect resulting from the carrier was detected histologically. Thus, intravitreal delivery of antisense oligonucleotides to modulate abnormal gene expression in retinal diseases may be an effective approach for ocular gene therapy.

Daytime consequences and correlates of insomnia in the United States: results of the 1991 National Sleep Foundation Survey. II

The daytime consequences and correlates of insomnia were examined in the National Sleep Foundation and the Gallup Organization survey of 1,000 randomly selected Americans. Respondents were grouped as having occasional insomnia, chronic insomnia or no insomnia. There were dramatic differences in reported waking behaviors and psychosocial measures by insomniacs compared to those who do not report sleep difficulty. These problems include impaired concentration, impaired memory, decreased ability to accomplish daily tasks and decreased enjoyment of interpersonal relationships. Importantly, most of these variables showed an increasing degree of impairment with greater frequency of sleep disturbance. These findings suggest that insomnia negatively impacts aspects of waking function related to quality of life.

The detection of brief daytime sleep episodes

INTRODUCTION

In the present study we evaluated the characteristics of sleep-onset detection (during daytime nap opportunities) as a function of differing sleep lengths among healthy, asymptomatic subjects.

METHODS

Twenty subjects were randomized into a Latin square design in which each subject received 1, 5, 10, and 20 minutes of sleep during an MSLT. Subjects were asked after each nap if they fell asleep. The rate of sleep detection was analyzed as a function of sleep duration.

RESULTS

Three subjects detected sleep onset after 1 minute of sleep, 7 subjects after 5 minutes of sleep, 10 subjects after 10 minutes of sleep, and 14 after 20 minutes of sleep (chi 2 = 9.63, p < .05).

CONCLUSIONS

The present data indicate the importance of sleep duration in an individual's ability to detect the occurrence of sleep. Importantly, only three subjects detected sleep after 1 minute of sleep, emphasizing the dangerous nature of brief sleep episodes in the context of public safety.

Psychometric evaluation of daytime sleepiness and nocturnal sleep onset scales in a representative community sample

BACKGROUND

The public health importance of daytime sleepiness as a risk factor for accidents, interpersonal problems, and decreased productivity has been recognized. However, epidemiologic research on this topic has been limited by the reliance on laboratory measures (i.e., the Multiple Sleep Latency Test-MSLT). Two scales, daytime sleepiness and nocturnal sleep onset, have been identified from the self-report Sleep-Wake Activity Inventory (SWAI) in a clinic sample and validated against the MSLT. This study evaluates the replicability of the two scales in a population sample and assesses potential thresholds in scale scores that distinguish normal from pathologic levels of daytime sleepiness and difficulty falling asleep.

METHODS

The sample consisted of 2181 subjects 18-45 years old in the Detroit metropolitan area. All sleep characteristic information covered the 2 weeks prior to interview. Split-half sample factor analyses were conducted to assess replicability of the results. Distribution of scale scores and their relation to construct validity variables were used to evaluate possible thresholds.

RESULTS

A two-factor model appeared to best account for the variation among the 12 items from the SWAI. The two factors accounted for 50% of the variance in both split-half sample analyses. The revised eight-item daytime sleepiness and two-item nocturnal sleep onset scales showed good and fair internal consistency respectively across both split-half samples. There appeared to be a "natural break" in daytime sleepiness scale scores that was associated with a substantial and consistent change in number of hours slept. No breaks appeared in nocturnal sleep onset scores.

CONCLUSIONS

This study replicated the results of the clinic-based study and suggested a potentially useful diagnostic threshold for self-report excessive daytime sleepiness. Epidemiology of sleep depends on the ability to move from the laboratory to population surveys in reliable and valid ways. Development of self-report is a step in that direction.

Ethanol as a hypnotic in insomniacs: self administration and effects on sleep and mood

The purpose of this study was to assess the effects of low ethanol doses on sleep and mood and to assess its reinforcing effects used as a hypnotic. Twenty healthy adults, aged 21-45 yrs, all moderate social drinkers, were studied: eleven subjects had insomnia and nine were normal sleepers, as documented by clinical polysomnography. On two sampling nights each, ethanol (0.5 g/kg) or placebo was administered before sleep in color-coded cups presented in three doses (0.2, 0.2, and 0.1 g/kg) separated by 15 min. On three subsequent nights subjects chose their preferred presleep beverage (0.2 g/kg ethanol or placebo) based on cup color and were given an opportunity for 3 additional refills (0.2 g/kg each) of the chosen beverage at 15 min intervals, yielding a total possible dose of 0.8 g/kg. Insomniacs chose ethanol 67% of nights and normals 22%. Insomniacs chose significantly more ethanol refills than normals for an average nightly dose of 0.45 g/kg and normals took significantly more placebo refills. On the sampling nights 0.5 g/kg ethanol reduced REM sleep for both groups for the 8-hr sleep period and in insomniacs increased stage 3-4 sleep and reduced stage 1 sleep during the first half of the night to the level seen in the normals. Other sleep variables were not altered in either group or halves of the night. Presleep improvements in the Profile of Mood States tension and concentration factors were also associated with ethanol administration. Thus, acutely, both sleep and mood effects appear to be associated with the reinforcing effects of ethanol as a hypnotic for insomniacs.

The behavioral morbidity of obstructive sleep apnea

The behavioral morbidity associated with obstructive sleep apnea (OSA) includes symptoms of excessive daytime sleepiness (EDS), neurocognitive deficits, psychological problems, and possibly an increased chance of accidents. EDS is among the most frequently reported symptoms in patients diagnosed with OSA. The available data suggest that the primary cause of EDS is sleep fragmentation. The subjective measures of sleepiness include the sleep wake activity inventory and the epworth sleepiness scale. Sleepiness can also be evaluated objectively in the sleep laboratory using the multiple sleep latency test or the maintenance of wakefulness test. The neurocognitive manifestations of OSA include impairments in vigilance, concentration, memory, and executive function. There is no agreed on consensus as to how to best quantify neurocognitive deficits in this population. Symptoms consistent with depression or personality changes have also been described, but are likely to be correlates of EDS and/or the chronicity of the disorder. Manifestations of the behavioral morbidity of OSA are reversible, but dependent on the degree of normalization in sleep-disordered breathing and the individual's sleep habits.

Application of grounded theory to content definition: a case study

Successful implementation of a clinical information system requires clinician involvement throughout the process of content definition and system development to ensure acceptance of the automated care process. In these times of downsizing, however, clinicians are not always able to participate fully in the dontent definition phase of system development and often become frustrated with their inability to obtain the patient information they need from the system. The qualitative research principles of grounded theory afford clinicians the opportunity to participate in content definition for information systems. This article presents a case study of the application of grounded theory to develop systematically the content definition for a clinical information system in preparation for implementation on four medical-surgical units.

Daytime CPAP titration: a viable alternative for patients with severe obstructive sleep apnea

OBJECTIVE

Continuous positive airway pressure (CPAP) is the treatment of choice for patients diagnosed with severe obstructive sleep apnea (OSA). The implementation of CPAP therapy has traditionally been based on full-night titration studies or split-night protocols. This study compared a group of patients who received a regular nocturnal CPAP titration with patients who received a daytime CPAP titration. The objective of the study was to determine if daytime CPAP titration is a viable alternative for the implementation of CPAP treatment in patients with severe OSA.

STUDY DESIGN

Fourteen patients (13 men and one woman) received a daytime CPAP titration (day group). The day group was matched to 18 patients (17 men and one woman) who were titrated under a full-night regular nocturnal study (night group). Eligible patients were those with severe OSA (respiratory event index > 40). The groups were matched by age, sex, and body mass index.

RESULTS

Daytime and nocturnal CPAP titration studies yielded sufficient amounts of rapid eye movement (REM) and non-REM sleep to help determine CPAP settings. Importantly, the diurnal and nocturnal CPAP titrations resulted in comparable therapeutic pressures as well as comparable resolution of sleep-disordered breathing. After 1 week of treatment, the groups exhibited similar CPAP use and comparable improvements in subjective sleepiness as indicated by their increase in sleep/wake activity inventory scores.

CONCLUSIONS

Daytime CPAP titration studies may be a viable alternative for the efficient and expedient implementation of CPAP therapy among some patients with severe OSA.

The effects of REM sleep deprivation on the level of sleepiness/alertness

STUDY OBJECTIVES

The purpose of this study was to evaluate the effects of acute REM deprivation on daytime sleepiness/alertness, as measured by the MSLT.

PARTICIPANTS

Twenty-six healthy, normal volunteers (14 males and 12 females) participated in this study. Participating subjects were in good physical and psychological health and were asymptomatic as to sleep/wake complaints.

INTERVENTIONS

Subjects spent 5 nights and 5 days in the laboratory. The first night and day were utilized for screening purposes. The remaining stay in the laboratory consisted of a baseline night and day, 2 deprivation nights and days, and a recovery night and day. Each night, a nocturnal polysomnogram was employed to monitor subjects' sleep. Each day, subjects underwent an MSLT to evaluate their sleepiness/alertness. Subjects were randomized into REM-deprivation (RD) and yoked-control (YC) groups. On deprivation nights, RD subjects were awakened each time they entered stage REM sleep, and the YC subjects were awakened concomitantly with the RD subjects, assuming they were not in stage REM sleep.

RESULTS

The REM-deprived subjects did not demonstrate any changes in MSLT scores across experimental days. In contrast, the YC subjects documented significantly lower MSLT scores on deprivation days due to decreased total sleep time.

CONCLUSION

The REM-deprivation procedure antagonized the effects of sleep loss on daytime sleepiness, resulting in increased alertness for RD subjects compared to YC subjects. The mechanism by which REM deprivation exerts its alerting effects is unknown and will require future research.

The perception of sleep as a function of the level of daytime sleepiness among patients with obstructive sleep apnea

Subjective estimates of sleep onset among patients with a variety of sleep disorders have been shown to be inaccurate. This inability in perceiving sleep onset is potentially dangerous for this population, in particular, for individuals who are required to drive long distances or operate heavy machinery as part of their daily activities. This study evaluated the perception of sleep among 237 consecutive patients diagnosed with obstructive sleep apnea. Patients completed an overnight sleep-laboratory evaluation followed by an objective evaluation of sleep propensity. The latter was done using the Multiple Sleep Latency Test (MSLT). Patients with an accurate perception of having slept on the MSLT were found to have shorter sleep latencies when compared with those with an inaccurate perception of their sleep. The results of this study suggest that the rapidity with which sleep is manifested is an important contributor to the accurate perception of sleep.