Procalcitonin is expressed in osteoblasts and limits bone resorption through inhibition of macrophage migration during intermittent PTH treatment

Intermittent injections of parathyroid hormone (iPTH) are applied clinically to stimulate bone formation by osteoblasts, although continuous elevation of parathyroid hormone (PTH) primarily results in increased bone resorption. Here, we identified Calca, encoding the sepsis biomarker procalcitonin (ProCT), as a novel target gene of PTH in murine osteoblasts that inhibits osteoclast formation. During iPTH treatment, mice lacking ProCT develop increased bone resorption with excessive osteoclast formation in both the long bones and axial skeleton. Mechanistically, ProCT inhibits the expression of key mediators involved in the recruitment of macrophages, representing osteoclast precursors. Accordingly, ProCT arrests macrophage migration and causes inhibition of early but not late osteoclastogenesis. In conclusion, our results reveal a potential role of osteoblast-derived ProCT in the bone microenvironment that is required to limit bone resorption during iPTH.

Mice Carrying a Ubiquitous R235W Mutation of Wnt1 Display a Bone-Specific Phenotype

Since a key function of Wnt1 in brain development was established early on through the generation of non-viable Wnt1-deficient mice, it was initially surprising that WNT1 mutations were found to cause either early-onset osteoporosis (EOOP) or osteogenesis imperfecta type XV (OI-XV). The deduced function of Wnt1 as an osteoanabolic factor has been confirmed in various mouse models with bone-specific inactivation or overexpression, but mice carrying disease-causing Wnt1 mutations have not yet been described. Triggered by the clinical analysis of EOOP patients carrying a heterozygous WNT1 mutation (p.R235W), we introduced this mutation into the murine Wnt1 gene to address the question of whether this would cause a skeletal phenotype. We observed that Wnt1^+/R235W and Wnt1^R235W/R235W mice were born at the expected Mendelian ratio and that they did not display postnatal lethality or obvious nonskeletal phenotypes. At 12 weeks of age, the homozygous presence of the Wnt1 mutation was associated with reduced trabecular and cortical bone mass, explained by a lower bone formation rate compared with wild-type littermates. At 52 weeks of age, we also observed a moderate bone mass reduction in heterozygous Wnt1^+/R235W mice, thereby underscoring their value as a model of WNT1-dependent EOOP. Importantly, when we treated wild-type and Wnt1^+/R235W mice by daily injection of parathyroid hormone (PTH), we detected the same osteoanabolic influence in both groups, together with an increased cortical thickness in the mutant mice. Our data demonstrate the pathogenicity of the WNT1-R235W mutation, confirm that controlling skeletal integrity is the primary physiological function of Wnt1, and suggest that osteoanabolic treatment with teriparatide should be applicable for individuals with WNT1-dependent EOOP. © 2020 American Society for Bone and Mineral Research.

Modifiable vascular risk factors, white matter disease and cognition in early Parkinson's disease

BACKGROUND AND PURPOSE

Dementia in Parkinson's disease (PD) is common and disabling. Identification of modifiable risk factors for it is essential. Vascular risk factors (VRFs) may be associated with cognitive decline in early PD. Biomarkers that serve as surrogates of the long-term effect of VRFs on PD are needed. To that end, we aimed to quantitate white matter hyperintensities (WMH) in early PD, measure associations with VRFs and examine relationships between WMH and longitudinal cognition.

METHODS

Participants in the Parkinson's Progression Markers Initiative study (141 patients with PD, 63 healthy controls) with adequate baseline structural brain magnetic resonance imaging data were included. Hypertension and diabetes history, and body mass index were combined to create a vascular risk score. WMH were quantitated via automated methods. Cognition was assessed annually with a comprehensive test battery.

RESULTS

In the PD group, vascular risk score was associated with WMH for total brain (β = 0.210; P = 0.021), total white matter (β = 0.214; P = 0.013), frontal (β = 0.220; P = 0.002) and temporal (β = 0.212; P = 0.002) regions. Annual rate of change in global cognition was greater in those with higher vascular risk score (β = -0.040; P = 0.007) and greater WMH (β = -0.029; P = 0.049). Higher temporal WMH burden was associated with great decline over time in verbal memory (β = -0.034; P = 0.031).

CONCLUSIONS

In early PD, modifiable VRFs are associated with WMH on brain magnetic resonance imaging. Temporal WMH burden predicts decline in verbal memory. WMH may serve as a surrogate marker for the effect of VRFs on cognitive abilities in PD.

Gastroesophageal reflux and obstructive sleep apnea

OBJECTIVE

To determine the extent to which gastroesophageal reflux (GER)-initiated laryngeal chemoreflexes contribute to obstructive sleep apnea (OSA).

METHODS

Prospective, nonrandomized clinical trial of an antireflux treatment protocol as a means of reducing the severity of OSA. Population consisted of 10 males aged 20 to 64 years with confirmed OSA (by overnight polysomnography) and GER (by ambulatory pH probe monitoring). Patients were treated with omeprazole and standard antireflux protocol for 30 days and pre- and posttreatment polysomnography variables were compared.

RESULTS

Mean apnea index declined 31% (45-31, P = .04); mean respiratory disturbance index declined 25% (62-46, P = .06). Three patients (30%) are "treatment responders" as defined by traditional OSA treatment definitions.

CONCLUSIONS

These results suggest a potential relationship between OSA and GER, the treatment of which may be an effective adjunctive in those with both disorders. Treatment of GER may significantly impact OSA in select individuals.

Sexual behavior in sleep, sleepwalking and possible REM behavior disorder: a case report

Seven cases of sexual behavior during sleep (SBS) have been recently reported. The subjects had histories of behavioral parasomnias as well as positive family histories of parasomnia. A 27 year-old man with a history of sexual behavior during sleep was reported. His sleep history disclosed sleepwalking (SW) since 9 years of age. He also developed episodes of highly disruptive and violent nocturnal behavior with dream enactment at age 20 years, which often resulted in physical injuries either to himself or his wife and infant. His wife also reported episodes of amnestic sexual behavior that began 4 years before referral. During the episodes, the patient typically procured his wife, achieving complete sexual intercourse with total amnesia. Physical and neurological diagnostic workups were unremarkable. Family history disclosed sleepwalking in his brother. He was put on 2mg/day of bedtime clonazepam with a remarkable clinical improvement. This case involves either the combination of violent and non-violent sleepwalking with SBS, or the superimposition of presumed REM sleep behavior disorder (RBD) on top of preexisting SW in a man who also developed SBS in adulthood. Thus, this is a case report of probable parasomnia overlap syndrome.

Correlation between blood adenosine metabolism and sleep in humans

Blood adenosine metabolism, including metabolites and metabolizing enzymes, was studied during the sleep period in human volunteers. Searching for significant correlations among biochemical parameters found: adenosine with state 1 of slow-wave sleep (SWS); activity of 5'-nucleotidase with state 2 of SWS; inosine and AMP with state 3-4 of SWS; and activity of 5'-nucleotidase and lactate with REM sleep. The correlations were detected in all of the subjects that presented normal hypnograms, but not in those who had fragmented sleep the night of the experiment. The data demonstrate that it is possible to obtain information of complex brain operations such as sleep by measuring biochemical parameters in blood. The results strengthen the notion of a role played by adenosine, its metabolites and metabolizing enzymes, during each of the stages that constitute the sleep process in humans.

Effects of zaleplon or triazolam with or without ethanol on human performance

Objectives and background: Given that non-selective gamma-aminobutyric acid (GABA) agonist hypnotics impair performance and potentiate the disruptive effects of ethanol, this study was done to determine the performance-impairing and ethanol-potentiating effects of zaleplon, a new selective GABA agonist hypnotic.Methods: Eighteen healthy men (12) and women (six), 31.5+/-5.6 years old, were studied. Each underwent six treatments of 2 days in duration, presented in a Latin square design with 2-12 recovery days between. The treatments were: placebo-placebo; placebo-ethanol; triazolam-placebo; triazolam-ethanol; zaleplon-placebo; and zaleplon-ethanol; with triazolam (0.25 mg) or placebo administered at 08:30 h, zaleplon (10 mg) or placebo at 09:00 h, and ethanol (0.75 g/kg) or placebo consumed from 09:30 h. Performance tests were completed each day at 10:30, 12:00 and 14:30 h.Results: Breath ethanol concentration (BrEC), tested 0.5, 2.0, 4.5 and 6 h post consumption, did not differ among treatments and peaked at 0.052%, declining to 0.037, 0.009 and 0.001%. Triazolam with and without ethanol impaired digit symbol substitution, symbol copying, simple and complex reaction times and divided attention performance relative to placebo-placebo treatment. It did so consistently at 10:30 and 12:00 h, and less consistently at 14:30 h. Zaleplon without ethanol impaired only digit symbol substitution and divided attention tracking, and only at 10:30 h. Zaleplon with ethanol impaired most measures at 10:30 and 12:00 h, but not at 14:30 h. Zaleplon without ethanol consistently differed from triazolam without ethanol in the extent of performance impairment. Zaleplon with ethanol began to differ from triazolam with ethanol in performance impairment on the 12:00 and 14:30 h test sessions. Ethanol itself impaired most measures at 10:30 h, fewer at 12:00 h and none at 14:30 h. All active drug treatments increased self-rated sleepiness compared with placebo-placebo. Triazolam without ethanol produced greater self-rated sleepiness than zaleplon without ethanol. The addition of ethanol to both drugs generally produced comparable levels of self-rated sleepiness.Conclusions: In an absolute sense, zaleplon produced less performance impairment and a shorter period of ethanol potentiation than triazolam.

Sleepiness/alertness among healthy evening and morning type individuals

Objective: The aim of this study was to determine the level of sleepiness/alertness among different chronotypes.Background: The Horne-Ostberg Morningness-Eveningness Questionnaire (MEQ) has allowed the characterization of chronotypes that are associated with a number of biological factors including: body temperature, cortisol rhythm, sleep patterns, and architecture.Methods: Fifty-six consecutive normal volunteers underwent an 8-h polysomnogram followed by a multiple sleep latency test (MSLT). Each subject also completed the MEQ and the Sleep/Wake Activity Inventory.Results: Evening types (ET) reported significantly later bedtimes and risetimes than both morning types (MT) and neither types (NT, P<0.05). On nocturnal polysomnography, the ET documented significantly longer latencies to stage 1 and persistent sleep when compared to both the NT and MT (P<0.01). There were no significant differences in the level of sleepiness on the MSLT across the different chronotypes. However, the pattern of sleepiness differed among them. While ET and NT showed differential sleep latencies across nap opportunities, MT showed no evidence of circadian variation on their level of sleepiness.Conclusions: There were no overall differences in daytime sleepiness/alertness across chronotypes. However, a differential pattern of sleep latencies was noted on the MSLT.

Inappropriate ICD therapy due to lead-related noise in an active fixation ICD lead

INTRODUCTION

Despite advances in technology, problems with effective ventricular endocardial sensing continue to arise and to result in inappropriate implantable cardioverter defibrillator (ICD) therapies.

METHODS AND RESULTS

The patient is a 79-year-old man with ischemic cardiomyopathy and ventricular tachycardia (VT) who received inappropriate ICD therapies due to lead-related noise detection. Noise was created by the distal helix, which was not fully deployed, intermittently contacting the internal guidepost of the lead (CPI, Guidant, model 0155). After the complete deployment of the helix the problem resolved and the pacing parameters remained stable.

CONCLUSION

To our knowledge, this is the first confirmed case report of non-physiologic sensing secondary to the incompletely deployed helix of an active fixation defibrillation lead. A design flaw with this lead led to its redesign to avoid noise over-sensing.

Treatment regimen and hypnotic self-administration

RATIONALE AND OBJECTIVES

Previous studies have shown that insomniacs self-administer hypnotics at high nightly rates. This study determined whether prior experience with different treatment regimens (i.e., instructions and capsule availability) would alter the previously observed high hypnotic self-administration rates.

METHODS

Sixty-four healthy men and women with (n = 32) and without (n = 32) insomnia, 21-55 years, self administered placebo or triazolam (0.25 mg) after different prior treatment regimens. They received one of three different treatment regimens enforced for 11 nights: a capsule each night, a capsule as needed, or a capsule every third night. On 14 subsequent nights they choose to self-administer a capsule or not, placebo during 1 week and triazolam (0.25 mg) the other (counterbalanced in order).

RESULTS

Insomniacs self-administered more capsules than normals and triazolam was self-administered more than placebo. For both groups, treatment regimen had a minimal effect on capsule self-administration. During the treatment phase, triazolam improved self-ratings of sleep relative to placebo. During the choice phase, nightly variations in self-rated sleep predicted self-administration of a capsule on the following night, regardless of whether the capsule was active drug or placebo.

CONCLUSIONS

The data of this study are consistent with the view that hypnotic self-administration by insomniacs is therapy-seeking behavior and not drug abuse.

Self-reported levels of sleepiness among subjects with insomnia

Objectives: To determine the prevalence of sleepiness in a cohort of insomnia subjects. We evaluated if differential levels of subjective sleepiness predict systematic differences in the polysomnographic characteristics of these subjects.Background: Insomnia is prevalent among the adult population. While it has been speculated that sleepiness may be an important daytime consequence of insomnia, this has not been demonstrated.Methods: Sixty-two subjects with complaints of insomnia for at least 6 months were polysomnographically evaluated. Subjects were asked to self-report their level of sleepiness based on their experiences for the previous 7 days. Subjects were divided into three groups based on their level of sleepiness. Sleepiness was determined using the excessive daytime sleepiness scale of the Sleep/Wake Activity Inventory (SWAI-EDS).Results: Twenty-two percent of insomnia subjects were found to be sleepy on the EDS scale of the SWAI. The level of sleepiness was also found to predict difficulty initiating sleep both on the nocturnal scale of the SWAI, and on nocturnal polysomnography.Conclusions: This study established a base rate of sleepiness among a cohort of insomnia subjects. It also demonstrated a wide spectrum of sleepiness/alertness among subjects with insomnia. Differential levels of sleepiness were found to predict nocturnal sleep latencies.

Public health risks of railroad hazardous substance emergency events

The number of railroad events reported to the Agency for Toxic Substances and Disease Registry's Hazardous Substances Emergency Events Surveillance system increased from 84 in 1993 to 177 in 1998. Comparisons of data on railroad and non-railroad events were made. The results overall indicated a greater potential impact of railroad events on public health. A median number of 2039 persons were living within a 1-mile radius of railroad events versus 982 for non-railroad events. The percentage of events during times when people are more likely to be home was also greater for railroad events. Railroad event victims were more likely to need hospital treatment than non-railroad event victims, which suggested the need for better community planning, reevaluation of current federal regulations and priorities for railroad hazardous material transport, and enhanced railroad industry commitment to safety.

Scoring reliability of the multiple sleep latency test in a clinical population

STUDY OBJECTIVES

To determine intrarater and interrater scoring reliability of the multiple sleep latency test (MSLT) in a population of sleep clinic patients.

DESIGN

N/A.

SETTING

Urban sleep center.

PATIENTS

200 consecutive sleep center patients (diagnoses included: obstructive sleep apnea, narcolepsy, periodic-limb-movement, and individuals with no diagnosis).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

MSLTs were recorded and scored according to standard clinical procedures. One of four clinical polysomnographers and one of seven polysomnographic technologists scored each MSLT. All MSLTs were then rescored by the same polysomnographer. The intrarater reliability coefficient for mean MSLT score was .87 and interrater reliability was .90. Coefficients for the mean number of REM onsets during the MSLT were .81 for intrarater and .88 for interrater reliability. Intrarater and interrater agreement (kappa coefficients) for the presence of at least one REM onset during the MSLT was .78 and .86, respectively. For the presence of greater than one REM onset, a kappa of .78 was obtained for intrarater agreement and .91 for interrater agreement.

CONCLUSIONS

The clinical MSLT displays excellent interrater and intrarater reliability estimates for both sleep latency and REM onset scores in a sleep-disordered population.

Efficacy of uvulopalatopharyngoplasty in unselected patients with mild obstructive sleep apnea

OBJECTIVES

Uvulopalatopharyngoplasty (UPPP) is widely used as a first-step procedure for the surgical management of obstructive sleep apnea (OSA) syndrome but best manages obstruction occurring at the level of the oropharynx alone and not the hypopharynx. Previous publications have noted mediocre results with use of this procedure in unselected patients with OSA, but less clear is the effectiveness of this procedure in the unselected patient with mild OSA (respiratory event index [REI] 5-25). Using objective and subjective criteria, we retrospectively analyzed the results of UPPP in patients with mild OSA.

METHODS

We examined 37 patients with mild OSA (REI 13.5 +/- 5.1, range 5.6-23.1) who had been operated on during 1996 with UPPP with or without tonsillectomy and/or septoplasty. Follow-up polysomnography was obtained in 25 (68%) an average of 40.5 weeks after surgery and compared with findings before surgery. Subjective assessment of sleepiness was performed with the Sleep-Wake Activity Inventory.

RESULTS

Ten patients (40%) had a postoperative reduction in the REI of more than 50%, comparable with the improvements reported in those with more severe apnea. Those who did not have a reduction in REI after surgery actually saw an increase in average REI from 16.6 +/- 5 to 26.7 +/- 18.4. Similarly, subjective assessment of sleepiness with the Sleep-Wake Activity Inventory showed no statistically significant improvement after surgery.

CONCLUSION

Overall, these results indicate that UPPP alone in the unselected patient provides little benefit in the management of mild OSA, similar to findings for more severe OSA. Surgeons must use great care in discerning the level of obstruction in the patient with mild OSA to tailor the appropriate retropalatal and/or retrolingual procedures and thereby achieve excellent surgical outcomes.

CPAP therapy in patients with mild OSA: implementation and treatment outcome

Objectives: To determine continuous positive airway pressure (CPAP) treatment compliance and reversal of excessive daytime sleepiness in patients with mild OSA.Background: CPAP therapy is the most widely accepted and used intervention in patients with a diagnosis of obstructive sleep apnea (OSA). There are, however, no widely accepted protocols to help guide the rational use of CPAP therapy. Patients with mild OSA (respiratory event index (REI) >5 or </=25) represent a subset of the OSA population where CPAP implementation needs to be evaluated.Methods: This is a retrospective study of 740 consecutive patients evaluated for sleep apnea in 1996. Mild OSA was documented in 241 patients, of whom, 41 opted for CPAP therapy. Implementation of CPAP treatment included an education session and an overnight clinical polysomnography (CPSG) for titration purposes. Patients returned for follow-ups after 1 week and 1 year of CPAP use. During each appointment, compliance and response to treatment were evaluated.Results: Of the initial 41 patients nine were lost to follow-up, 16 discontinued CPAP use during the first week, and 16 were still using CPAP after 1 year. For the 16 still using CPAP after one year, hours of use the first week was correlated to hours of use the first year (r=0.81). Patients using CPAP more than 4 h/night experienced a marked improvement in daytime sleepiness after 1 year (P<0.01).Conclusions: Patients with mild OSA showed a high rate of CPAP discontinuation. Those patients who manifested good compliance during the first week of treatment continued using CPAP for the entire first year. These patients experienced improved alertness during the day. A 1 week trial on CPAP therapy is warranted to identify patients who benefit from this form of therapy.

Performance of black and white South African children on the Wechsler Intelligence Scale for Children--Revised and the Kaufman Assessment Battery

The validity of traditional intelligence tests for cultural groups that differ from those for whom the tests were normed has come under scrutiny. This is particularly the case for the previously disadvantaged black majority in South Africa. The Kaufman Assessment Battery for Children (K-ABC) is reportedly a relatively nondiscriminatory test of intellectual functioning. This study compared the performance of 21 black and 35 white third-grade South African children on the K-ABC and the Wechsler Intelligence Scale--Revised (WISC-R) at two schools for children with learning problems. While the WISC-R Verbal and Full Scale IQ of black children were significantly lower than that of whites, there was no significant difference between these groups on the K-ABC. Teachers' ratings for white and black pupils were acceptably concordant with students' performance on the K-ABC but not on the WISC-R. Support is provided for the usefulness of the K-ABC as a relatively nondiscriminatory alternative to the WISC-R for South African children.

Thyroid testing and thyroid hormone replacement in patients with sleep disordered breathing

The current literature recommends that patients who have symptoms of sleep disordered breathing should be evaluated for hypothyroidism. Thyroid hormone replacement therapy has been reported by some authors to be effective in treating obstructive sleep apnea in hypothyroid patients. The present study prospectively evaluated the prevalence of hypothyroidism in 1,000 consecutively presenting patients who came to the office for evaluation of snoring or obstructive sleep apnea syndrome. The authors also examined the efficacy of treatment for hypothyroidism on sleep apnea in patients with both disorders. Of the 1,000 patients, routine thyroid testing was performed on 834; only 10 of these patients (1.2%) were discovered to have previously undiagnosed clinical hypothyroidism. Four of the 10 patients with newly diagnosed clinical hypothyroidism had obstructive sleep apnea syndrome, and they received thyroid hormone replacement therapy. Once these four patients achieved a euthyroid state, repeat polysomnography showed that there was no significant difference between their pre- and posttreatment respiratory disturbance index. Based on the results of our study, we conclude the following: 1) The prevalence of hypothyroidism in patients who are evaluated for sleep disordered breathing is no greater than that of the general population. 2) Thyroid replacement therapy results in little or no improvement in sleep apnea in patients with clinical hypothyroidism. 3) Routine thyroid function screening is not indicated for patients who are being evaluated for sleep disordered breathing.

Narcolepsy and other causes of excessive daytime sleepiness

Narcolepsy is a chronic disorder characterized by excessive daytime sleepiness, cataplexy, and other auxiliary symptoms. An interview can ascertain specific symptomatology, whereas a polysomnogram can reveal distinct clinical features. The clinical and laboratory evaluation together enable an accurate diagnosis of narcolepsy. This diagnosis includes a wide spectrum of symptom combinations. Treatment of narcolepsy should include the empathic guidance of a sleep clinician, an emphasis on sleep hygiene, and in many cases pharmacotherapy.

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.

Group supervision of groups: a modern analytic perspective

This article is introduced by historical references to Freud's Wednesday Evening Society and to relevant sources in the literature on group supervision. The aims of group supervision are defined: helping supervisees to understand the individuals who comprise their groups, helping the supervisee become a group-oriented therapist, alerting supervisees to the critical task of monitoring and regulating the amount of emotional excitation within their groups, helping supervisees deal with the range of feelings induced in them by their groups, and helping them become familiar with the principles and become proficient in the techniques of modern analysis. Major aspects of the group-supervisory process are delineated and illustrated through the use of relevant vignettes. Resistance in supervisory groups is discussed with examples of the resolution of some resistances. The author's method and style of leading supervisory groups is presented, as are observations on the boundaries of supervisory groups.

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.

Relation between impedance and electrode temperature during radiofrequency catheter ablation of accessory pathways and atrioventricular nodal reentrant tachycardia

OBJECTIVES

Impedance monitoring has been proposed as a method to assess the adequacy of tissue heating during catheter ablation procedures. The purpose of this study was to evaluate the relation among initial impedance, fall in impedance, and electrode temperature during catheter ablation procedures.

METHODS AND RESULTS

Data from 248 applications of radiofrequency energy in 45 consecutive patients (26 with accessory pathways and 19 with atrioventricular nodal reentrant tachycardia) referred for catheter ablation were analyzed. The initial impedance was higher during ablation of accessory pathways than during atrioventricular nodal reentrant tachycardia (116+/-66 versus 106+/-80 omega, P < .001). In both groups, a significant correlation was observed between the initial impedance and temperature (R = 0.98, P < .001). After accounting for differences between patients and ablation targets, an even closer correlation was observed (accessory pathways: R = 0.95, P < .0001; atrioventricular nodal reentrant tachycardia: R = 0.94, P < .0001).

CONCLUSION

These data suggest that monitoring of the initial impedance and the fall in impedance during ablation procedures may provide clinically valuable information to assess the efficacy of tissue heating and lesion formation.

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.

Relationship between the upper limit of vulnerability determined in normal sinus rhythm and the defibrillation threshold in patients with implantable cardioverter defibrillators

The upper limit of vulnerability is the strength above which ventricular fibrillation is no longer inducible with a shock delivered during the vulnerable phase of the cardiac cycle. It has been demonstrated that the upper limit of vulnerability correlates with the defibrillation threshold in a paced rhythm. The purpose of this study is to evaluate the correlation of the upper limit of vulnerability determined in normal sinus rhythm with the defibrillation threshold using a simplified protocol in patients undergoing placement of an ICD. We studied 28 patients who underwent ICD implantation. CPI generators and Endotak leads were used in all patients. Device-based testing was used to determined the defibrillation threshold and the upper limit of vulnerability. The upper limit of vulnerability was tested with three shocks delivered at 0, 20, and 40 ms before the peak of the T wave during normal sinus rhythm. The defibrillation threshold was determined by a simple step up-down protocol. The upper limit of vulnerability (9.0 +/- 4.5 J) did not significantly differ from the defibrillation threshold (9.9 +/- 4.0 J), P = NS. A close correlation was present, correlation coefficient = 0.75, P < 0.0001. The upper limit of vulnerability was within 5 J of the defibrillation threshold in 27 (96%) of the 28 patients. The upper limit of vulnerability underestimated the defibrillation threshold by 10 J in one patient who had a defibrillation threshold of 15 J. The upper limit of vulnerability determined in normal sinus rhythm correlates significantly with the defibrillation threshold in patients undergoing ICD implantation. The protocol is simple and easily implemented clinically.

The siesta culture concept is not supported by the sleep habits of urban Mexican students

Evidence in support for the concept of the so-called 'siesta culture' is not well developed and has, to date, relied largely on qualitative anthropological data. Presumably such cultures are characterized by a strong tendency for daytime naps and daytime sleepiness, phenomena which may partially represent the effects of geographic, climatic or light conditions and/or cultural influences. In this study we surveyed the nocturnal sleep habits and daytime sleep tendencies of 577 Mexican college students residing in Mexico City (19 degrees N latitude). Results indicated a number of parallels between the reported sleep habits of these students and those reported from other cultures at latitudes far to the north (North America, Europe), such as longer sleep at the weekends, an association between snoring and daytime sleepiness and a lack of relationship between nocturnal sleep duration and the reported tendency to nap. There was some suggestion that these Mexican students may actually nap less when compared to other college student populations. Taken together, these results call into question what is meant by the concept of a 'siesta culture', at least in this urban, educated, upper social economic scale (SES) population, and suggest that future studies in equatorial regions be undertaken to further appreciate the role of climate, photoperiod and/or culture in the tendency for humans to nap during the day.