Comparison of Polysomnography, Single-Channel Electroencephalogram, Fitbit, and Sleep Logs in Patients With Psychiatric Disorders: Cross-Sectional Study.

BACKGROUND: Sleep disturbances are core symptoms of psychiatric disorders. Although various sleep measures have been developed to assess sleep patterns and quality of sleep, the concordance of these measures in patients with psychiatric disorders remains relatively elusive. OBJECTIVE: This study aims to examine the degree of agreement among 3 sleep recording methods and the consistency between subjective and objective sleep measures, with a specific focus on recently developed devices in a population of individuals with psychiatric disorders. METHODS: We analyzed 62 participants for this cross-sectional study, all having data for polysomnography (PSG), Zmachine, Fitbit, and sleep logs. Participants completed questionnaires on their symptoms and estimated sleep duration the morning after the overnight sleep assessment. The interclass correlation coefficients (ICCs) were calculated to evaluate the consistency between sleep parameters obtained from each instrument. Additionally, Bland-Altman plots were used to visually show differences and limits of agreement for sleep parameters measured by PSG, Zmachine, Fitbit, and sleep logs. RESULTS: The findings indicated a moderate agreement between PSG and Zmachine data for total sleep time (ICC=0.46; P<.001), wake after sleep onset (ICC=0.39; P=.002), and sleep efficiency (ICC=0.40; P=.006). In contrast, Fitbit demonstrated notable disagreement with PSG (total sleep time: ICC=0.08; wake after sleep onset: ICC=0.18; sleep efficiency: ICC=0.10) and exhibited particularly large discrepancies from the sleep logs (total sleep time: ICC=-0.01; wake after sleep onset: ICC=0.05; sleep efficiency: ICC=-0.02). Furthermore, subjective and objective concordance among PSG, Zmachine, and sleep logs appeared to be influenced by the severity of the depressive symptoms and obstructive sleep apnea, while these associations were not observed between the Fitbit and other sleep instruments. CONCLUSIONS: Our study results suggest that Fitbit accuracy is reduced in the presence of comorbid clinical symptoms. Although user-friendly, Fitbit has limitations that should be considered when assessing sleep in patients with psychiatric disorders.

Prevalence of obstructive sleep apnea as assessed by polysomnography in psychiatric patients with sleep-related problems.

PURPOSE: Patients with psychiatric disorders often complain of sleep disturbances and are frequently suspected of obstructive sleep apnea (OSA). However, data regarding sleep problems evaluated by attended polysomnography (PSG) remain limited in this population. We analyzed the results of attended PSG from psychiatric patients with sleep-related problems to determine the prevalence and features of sleep disorders among this population. METHODS: We retrospectively investigated the attended PSG results of patients with psychiatric disorders: major depressive disorder, bipolar disorder, neurodevelopmental disorder, schizophrenia, neurocognitive disorder, anxiety disorder, somatic symptom disorder. RESULTS: Of 264 patients, 158 men (60%), mean age was 47 ± 19.9 years. More than half of the patients with major depressive disorder (62%), bipolar disorder (70%), schizophrenia (58%), neurocognitive disorders (55%), and somatic symptom disorder (56%) had OSA. Among the psychiatric patients with OSA, 62% of these patients had moderate to severe OSA. The risk factors for OSA were snoring, male, age, and body mass index. The presence of OSA was not associated with the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale score, or benzodiazepine, antipsychotic, or antidepressant use. Other sleep disorders were insomnia (19%), central disorders of hypersomnia (8%), restless legs syndrome/periodic limb movement of sleep (8%), rapid eye movement sleep behavior disorder (7%), and central sleep apnea syndrome (3%). CONCLUSIONS: PSG revealed that moderate to severe OSA was common in psychiatric patients with or without snoring. Subjective symptoms and psychotropics did not predict OSA. Therefore, PSG is needed to reveal sleep conditions in patients with psychiatric disorders.

Performance of an ambulatory electroencephalogram sleep monitor in patients with psychiatric disorders.

Key clinical symptoms observed among individuals with psychiatric disorders include difficulty falling asleep or maintaining sleep, poor sleep quality and nightmares. Those suffering from sleep disorders often present with symptoms of discontent with regard to sleep quality, timing and quantity, and these symptoms have an adverse impact on function and quality of life. A minimally invasive technique would be preferable in patients with psychiatric disorders, who tend to be sensitive to environmental change. Accordingly, we evaluated the performance of Zmachine Insight Plus, an ambulatory electroencephalography sleep monitor, in patients with psychiatric disorders. One hundred and three patients undergoing polysomnography were enrolled in this study. Zmachine Insight Plus was performed simultaneously with polysomnography. Total sleep time, sleep efficiency, wake after sleep onset, rapid eye movement (REM) sleep, light sleep (stages N1 and N2) and deep sleep (stage N3) were assessed. Total sleep time, sleep efficiency, wake after sleep onset, REM sleep duration and non-REM sleep duration of Zmachine Insight Plus showed a significant correlation with those of polysomnography. Lower sleep efficiency and increased frequency of waking after sleep onset, the arousal index and the apnea-hypopnea index on polysomnography were significantly associated with the difference in sleep parameters between the two methods. Among patients with psychiatric disorders who are sensitive to environmental change, Zmachine Insight Plus would be a useful technique to objectively evaluate sleep quality.

Forced expression of miR-143 and -145 in cardiomyocytes induces cardiomyopathy with a reductive redox shift.

BACKGROUND: Animal model studies show that reductive stress is involved in cardiomyopathy and myopathy, but the exact physiological relevance remains unknown. In addition, the microRNAs miR-143 and miR-145 have been shown to be upregulated in cardiac diseases, but the underlying mechanisms associated with these regulators have yet to be explored. METHODS: We developed transgenic mouse lines expressing exogenous miR-143 and miR-145 under the control of the alpha-myosin heavy chain (αMHC) promoter/enhancer. RESULTS: The two transgenic lines showed dilated cardiomyopathy-like characteristics and early lethality with markedly increased expression of miR-143. The expression of hexokinase 2 (HK2), a cardioprotective gene that is a target of miR-143, was strongly suppressed in the transgenic hearts, but the in vitro HK activity and adenosine triphosphate (ATP) content were comparable to those observed in wild-type mice. In addition, transgenic complementation of HK2 expression did not reduce mortality rates. Although HK2 is crucial for the pentose phosphate pathway (PPP) and glycolysis, the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) was unexpectedly higher in the hearts of transgenic mice. The expression of gamma-glutamylcysteine synthetase heavy subunit (γ-GCSc) and the in vitro activity of glutathione reductase (GR) were also higher, suggesting that the recycling of GSH and its de novo biosynthesis were augmented in transgenic hearts. Furthermore, the expression levels of glucose-6-phosphate dehydrogenase (G6PD, a rate-limiting enzyme for the PPP) and p62/SQSTM1 (a potent inducer of glycolysis and glutathione production) were elevated, while p62/SQSTM1 was upregulated at the mRNA level rather than as a result of autophagy inhibition. Consistent with this observation, nuclear factor erythroid-2 related factor 2 (Nrf2), Jun N-terminal kinase (JNK) and inositol-requiring enzyme 1 alpha (IRE1α) were activated, all of which are known to induce p62/SQSTM1 expression. CONCLUSIONS: Overexpression of miR-143 and miR-145 leads to a unique dilated cardiomyopathy phenotype with a reductive redox shift despite marked downregulation of HK2 expression. Reductive stress may be involved in a wider range of cardiomyopathies than previously thought.

Patient characteristics affecting accurate detection of sleep apnea using a bed sheet-type portable monitor.

PURPOSE: Although performed inside a laboratory, attended polysomnography (PSG) has long been the gold standard for the diagnosis of sleep apnea. However, high costs and long wait times have led to the development of home-based portable monitoring devices. A bed sheet-shaped device called SD102 (Suzuken Co., Nagoya, Japan) has been developed, and its accuracy in evaluating sleep apnea is becoming evident. The purpose of this study was to confirm the accuracy of SD102 in evaluating sleep apnea and to investigate patient characteristics that may contribute to inaccurate test results in patients with suspected obstructive sleep apnea (OSA). METHODS: One hundred and eighty-nine patients simultaneously underwent PSG and portable monitoring by using a home sleep apnea testing (HSAT) device. A blinded, experienced technologist using the American Academy of Sleep Medicine criteria versions 2.1 and 2.3 scored the PSG data and HSAT device data, respectively. RESULTS: The respiratory event index (REI) by HSAT significantly correlated with the apnea-hypopnea index (AHI) by PSG (r = 0.974, p < 0.001). HSAT sensitivity, specificity, and positive and negative predictive values of 0.99, 0.83, 0.95, and 0.97, respectively. Body mass index and arousal index were significantly associated with the difference between REI from SD102 HSAT and AHI from PSG. CONCLUSIONS: This study demonstrates the good agreement between REI and AHI in patients with suspected OSA and suggests that understanding the limitations of different testing methods may help in the accurate detection of OSA.

Effects of sleep-disordered breathing and hypertension on cognitive function in elderly adults.

Purpose: The prevalence of sleep-disordered breathing (SDB) increases with aging. SDB is a risk of hypertension, and both might lead to cognitive decline. However, the role of SDB and hypertension on the pathogenesis of age-related cognitive decline remains unclear. We examined the effects of these two diseases on cognitive function in elderly adults.Methods: Fifty-two elderly individuals (mean age, 69.6 ± 4.0 years) free from impairment in daily living activities participated in this study. Apnea/hypopnea index (AHI) and minimum oxygen saturation (SpO2) were assessed using a portable home monitoring device. We evaluated excessive daytime sleepiness with the Epworth sleepiness scale (ESS). Cognitive performance was assessed using the Wisconsin card sorting test (WCST), continuous performance test-Identical pairs (CPT-IP), and N-back task. Hypertension and diabetes mellitus were evaluated via questionnaire and blood pressure value.Results: The WCST category achievement was significantly lower in participants with minimum SpO2 <90% than those with minimum SpO2 ≥90%. The percentage of correct answer on the 0- and 1-back tasks was significantly lower in the hypertensives than normotensives. Minimum SpO2 was correlated with category achievement on the WCST. Multiple regression analysis including age, sex, body mass index, AHI, minimum SpO2, ESS, hypertension, and diabetes mellitus revealed that hypertension was the most significant factor for percentage correct answers on the 0- and 1-back tasks. There were no significant correlations between body mass index, ESS or diabetes mellitus and the parameters of WCST, CPT-IP, or N-back tasks.Conclusion: In elderly adults, nocturnal hypoxia and hypertension had a negative effect on cognitive function.

Hydrogen gas improves left ventricular hypertrophy in Dahl rat of salt-sensitive hypertension.

PURPOSE: Hypertension is an important risk factor for death resulting from stroke, myocardial infarction, and end-stage renal failure. Hydrogen (H2) gas protects against many diseases, including ischemia-reperfusion injury and stroke. The effects of H2 on hypertension and its related left ventricular (LV) function have not been fully elucidated. The purpose of this study was to investigate the effects of H2 gas on hypertension and LV hypertrophy using echocardiography. METHODS: Dahl salt-sensitive (DS) rats were randomly divided into three groups: those fed an 8% NaCl diet until 12 weeks of age (8% NaCl group), those additionally treated with 2% H2 gas (8% NaCl + 2% H2 group), and control rats maintained on a diet containing 0.3% NaCl until 12 weeks of age (0.3% NaCl group). H2 gas was supplied through a gas flowmeter and delivered by room air (2% hydrogenated room air, flow rate of 10 L/min) into a cage surrounded by an acrylic chamber. We evaluated interventricular septal wall thickness (IVST), LV posterior wall thickness (LVPWT), and LV mass using echocardiography. RESULTS: IVST, LVPWT, and LV mass were significantly higher in the 8% NaCl group than the 0.3% NaCl group at 12 weeks of age, whereas they were significantly lower in the 8% NaCl + 2% H2 group than the 8% NaCl group. There was no significant difference in systolic blood pressure between the two groups. CONCLUSION: Our findings suggest that chronic H2 gas inhalation may help prevent LV hypertrophy in hypertensive DS rats.

Very low frequency component of heart rate variability as a marker for therapeutic efficacy in patients with obstructive sleep apnea: Preliminary study.

BACKGROUND: Although positive airway pressure (PAP) therapy is effective for treating obstructive sleep apnea (OSA), some patients with severe OSA are intolerable to this treatment, which may lead to an increase in the mortality and morbidity of cardiovascular diseases. We investigated the relationship between heart rate variability (HRV) and sleep parameters during natural sleep and treatment of patients with OSA. MATERIALS AND METHODS: This was the cross-sectional observation study. Patients were 17 males with severe OSA who were unable to accept continuous PAP. Standard polysomnography was performed for two consecutive nights, i.e., during natural sleep and following night with bilevel PAP (BiPAP) treatment. Time-dependent responses of the amplitudes of low frequency (LF), very low frequency (VLF), and high frequency components of HRV were assessed with the technique of complex demodulation. RESULTS: Apnea-hypopnea index, oxygen desaturation time, and percentage of stage 1 sleep were significantly reduced, whereas the percentages of rapid eye movement and stages 3 + 4 sleep were increased, by BiPAP treatment. Therapy also reduced the amplitudes of VLF and LF components of HRV. Difference in amplitudes of VLF during natural sleep and treatment with BiPAP was significantly correlated with difference in percentages of stage 1 and stages 3 + 4 sleep. CONCLUSION: Therapy-induced amelioration of OSA and sleep quality was accompanied by decrease in the amplitudes of VLF components of HRV. The VLF component may thus reflect physiological changes in both autonomic activity and sleep structure and serve as an objective marker for therapeutic efficacy in patients with severe OSA.

Effects of hypnotics on prefrontal cortex activity during a verbal fluency task in healthy male subjects: A near-infrared spectroscopy study.

OBJECTIVE: To assess the effects of hypnotics on prefrontal cortex activity in healthy subjects using near-infrared spectroscopy (NIRS) in a double-blind, placebo-controlled crossover trial. METHODS: Eighteen healthy males received acute doses of ramelteon (8 mg), triazolam (0.125 mg), or placebo in a predetermined randomization schedule, with a washout period of more than 1 week. All subjects performed a verbal fluency task during NIRS assessments at baseline and at 1 and 4 hr post-dose. The number of words correctly generated during the task (behavioral performance) and scores on the Stanford Sleepiness Scale (SSS) were also recorded at each test time. RESULTS: Compared with the placebo, triazolam (0.125 mg) significantly decreased oxyhemoglobin (oxy-Hb) concentration change in NIRS during the posttask period and significantly increased behavioral performance, whereas triazolam (0.125 mg) and ramelteon (8 mg) significantly increased SSS scores. CONCLUSIONS: The differential effects of two types of hypnotics on oxy-Hb change measured by NIRS were observed in acute dosing, suggesting that when assessing brain activity of patients with psychiatric disorders, researchers should consider how certain types of hypnotics can influence brain function. This would also provide useful information to clinicians when prescribing hypnotics suitable for their patients' conditions.

REM sleep without atonia in middle-aged and older psychiatric patients and Lewy body disease: a case series.

OBJECTIVE: Rapid eye movement (REM) sleep behavior disorder (RBD) is commonly associated with Lewy body disease, narcolepsy, or depression. In contrast, the relationship between REM sleep without atonia (RWA), which is a hallmark of RBD on polysomnography, and clinical characteristics remains unclear. The purpose of this study is to investigate the clinical features of psychiatric patients exhibiting RWA and its relevance to Lewy body disease. METHODS: Of 55 consecutive patients who underwent polysomnography at the psychiatric ward, 25 patients with sleep apnea syndrome were excluded, and 12 patients exhibiting RWA were identified. The clinical profiles were compared between the groups with and without RWA. RESULTS: The mean age and the frequency of neurocognitive disorders were significantly higher in 12 patients with RWA than in 18 without. Only five of the 12 patients exhibiting RWA had episodes of dream-enactment behavior, and fulfilled the clinical criteria for RBD. Two young patients were diagnosed with narcolepsy, while the other middle-aged and older patients fulfilled the clinical criteria for Parkinson's disease (n = 1), dementia with Lewy bodies (n = 4), idiopathic RBD (n = 2), and major depressive disorder (MDD) (n = 3). The patients with MDD exhibited constipation and/or olfactory dysfunction. Moreover, neuroimaging examinations in the patients with MDD revealed isolated occipital hypoperfusion in three patients and mild dopamine transporter deficit in one patient. CONCLUSIONS: Rapid eye movement sleep without atonia itself may be associated with specific clinical profiles, even when dream-enactment behavior is absent. Continued follow-up of the patients with MDD exhibiting RWA is warranted to determine if they represent the prodromal Parkinson's disease/dementia with Lewy bodies. Copyright © 2016 John Wiley & Sons, Ltd.

Influence of sleep duration on cortical oxygenation in elderly individuals.

AIM: Short sleep duration is a risk factor for cardiovascular diseases. Cerebral blood flow and its regulation are affected by pathological conditions commonly observed in the elderly population, such as dementia, atherosclerosis, diabetes mellitus (DM), stroke, and hypertension. The purpose of this study was to examine the influence of sleep duration on cortical oxygenated hemoglobin (OxyHb) using near-infrared spectroscopy (NIRS). METHODS: Seventy-three individuals (age, 70.1 ± 3.9 years, 51 men and 22 women) participated in this study. Cortical OxyHb levels were measured with NIRS. We evaluated age, body mass index (BMI), smoking status, alcohol intake, sleep duration, hypertension, DM, and hyperlipidemia using a questionnaire. Blood pressure was measured using plethysmography. RESULTS: Peak OxyHb and area under the NIRS curve significantly decreased in participants with sleep duration <7 h compared with those with sleep duration ≥7 h (0.136 ± 0.212 mM·mm vs 0.378 ± 0.342 mM·mm, P = 0.001; 112.0 ± 243.6 vs 331.7 ± 428.7, P = 0.012, respectively). Sleep duration was significantly correlated with peak OxyHb level and area under the NIRS curve (r = 0.378, P = 0.001; r = 0.285, P = 0.015, respectively). Multiple regression analysis, including age, BMI, sex, smoking status, alcohol intake, sleep duration, hypertension, DM, and hyperlipidemia revealed that sleep duration was the only significant independent factor associated with peak OxyHb and area under the NIRS curve (ß = 0.343, P = 0.004; ß = 0.244, P = 0.049, respectively), and smoking status was independently correlated with time to the peak OxyHb (ß = -0.319, P = 0.009). CONCLUSION: Sleep duration may be an important factor that influences cortical oxygenation in the elderly population.

Endomyocardial radial strain rate imaging during dobutamine stress echocardiography for the evaluation of contractile reserve in patients with dilated cardiomyopathy.

PURPOSE: Myocardial contractile reserve is associated with clinical prognosis in patients with dilated cardiomyopathy (DCM). We assessed myocardial contractile reserve using tissue Doppler strain rate imaging with dobutamine stress echocardiography in DCM patients. METHODS: Simultaneous echocardiography and left ventricular (LV) catheterization during dobutamine stress were performed in 20 patients with DCM, and echocardiography was performed in 31 control subjects. Dobutamine was infused at a starting dose of 5 µg/kg/min for 5 minutes and then at 10 µg/kg/min. Peak endomyocardial radial strain (ɛ) and systolic strain rate (SRsys ) measured with echocardiography and the maximum first derivative of LV pressure (LV dP/dtmax ) derived from catheterization were used as indices of contractility. Their percentage change from baseline to the dose of 10 µg/kg/min was calculated. RESULTS: The ɛ and SRsys were significantly smaller in DCM patients than in controls. The LV dP/dtmax , ɛ, and SRsys were significantly higher at the dose of 10 µg/kg/min than at baseline. The percentage change in SRsys was significantly correlated with the percentage change in LV dP/dtmax . CONCLUSIONS: Strain rate imaging during dobutamine stress in DCM might prove noninvasively informative for the evaluation of myocardial contractile reserve and provide insight into LV systolic dysfunction. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:555-560, 2016.

The Effect of Habitual Physical Training on Left Ventricular Function During Exercise Assessed by Three-Dimensional Echocardiography.

BACKGROUND: Stroke volume (SV) in trained athletes continuously increases with progressive exercise intensity. We studied whether physical training affected left ventricle (LV) function response to exercise using 3D echocardiography and tissue Doppler imaging (TDI). METHODS: Eleven male university athletes and 12 male university nonathletes were enrolled in this study. After baseline data were collected, subjects performed a symptom-limited supine bicycle ergometer exercise test. Initial workload was 25 Watts (W) and increased 25 W every 3 minutes. At rest and every exercise stage, LV end-systolic and diastolic volume index (LVEDVI and LVESVI), SV index (SVI), cardiac index (CI), LV ejection fraction (LVEF), and early lateral mitral flow velocity (Ea) were evaluated. Heart rate (HR), and systolic and diastolic blood pressure (SBP and DBP) were continuously recorded. RESULTS: Nonathletes showed a slow increase in CI, and SVI reached a plateau value at a HR of 90 beats per minute (bpm). In contrast, CI and SVI increased progressively and continuously in athletes. Both CI and SVI were significantly higher in athletes than in nonathletes at HRs of 100, 110, and 120 bpm. LVEDVI kept increasing in athletes while it plateaued in nonathletes. In contrast, LVESV decreased continuously during exercise in both groups. There was no significant difference in LVEF, Ea, SBP, or DBP at rest and during exercise between the two groups. CONCLUSION: LV responses to exercise in athletes were different from those of in nonathletes; thus, habitual physical training may play an important role in the increase in both SVI and CI in young individuals.

Smoking acutely impaired endothelial function in healthy college students.

OBJECTIVE: Cigarette smoking has been clearly pointed out as a risk factor for cardiovascular disease. Endothelial dysfunction contributes to the development of cardiovascular disease. Flow-mediated dilation (FMD) has been known as one of the endothelial function markers. We investigated the acute and chronic effects of smoking on endothelial function in college-aged smokers. METHODS: Eighteen smokers (mean age: 21 +/- 1 y) and 14 non-smokers (mean age: 20 +/- 1 y) were enrolled in this study. Brachial-ankle pulsed wave velocity (baPWV), systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were measured using a plethysmograph. Endothelium- dependent FMD was induced by reactive hyperaemia. High-resolution ultrasound with a 7.5-MHz linear array transducer was used to measure the diam- eter of the right brachial artery. Measurement of baPWV, SBP, DBP, HR, artery diameter, and %FMD was performed in smokers and non-smokers after 10 min bed rest, and after smoking one cigarette in the smokers. The interval between the two measurements was more than 15 minutes. RESULTS: There were no significant differences on baPWV, SBP, DBP, HR, baseline brachial artery diameter between smokers and non-smokers. Percent FMD after smoking was significantly lower than that at rest values in smokers (8.7 +/- 4.0 vs. 5.3 +/- 2.4, P < 0.005), although %FMD at rest was not significantly different between smokers and non-smokers. No other markers showed any significant differences between smokers at rest and after smoking. CONCLUSION: Even the smoking of one cigarette dramatically impaired endothelial function, although habitual cigarette smoking did not decrease FMD in young healthy smokers.

The effects of acute treatment with paroxetine, amitriptyline, and placebo on the equilibrium function in healthy subjects: a double-blind crossover trial.

OBJECTIVE: Depression is common in old age, and is treatable with antidepressants. However, antidepressants use can increase the risk of falls. Thus, we assessed the effects of antidepressants on equilibrium function using posturography. METHODS: This study recruited 10 healthy male volunteers (35.3 ± 3.7 years). In this double-blinded, three-way crossover trial, they received acute doses of 10 mg paroxetine, 25 mg amitriptyline, and placebo. They were administered posturography at baseline and 4-h postdosing. RESULTS: At 4-h postdosing, amitriptyline significantly decreased the locus length per unit area (L/A) and increased the envelope area compared with those at baseline. Meanwhile, the total length and the locus length per time (L/T) at 4-h postdosing of amitriptyline did not show significant differences from those at baseline. After paroxetine treatment, there were no significant differences in total length, L/T, L/A, and the envelope area between baseline and 4-h postdosing. CONCLUSION: An acute dose of amitriptyline significantly decreased L/A and increased the envelope area as markers of body sway. Evaluation of equilibrium function is important for preventing the potential risk of falls and body sway after taking antidepressants.

Blood Pressure Regulation and Hypertension in Obstructive Sleep Apnea Syndrome: A Historical Perspective.

In obstructive sleep apnea syndrome (OSAS), an underlying disease of secondary hypertension, repeated episodes of asphyxia due to obstructive sleep apnea (OSA), followed by arousal, lead to various cardiovascular consequences. Using a canine model of OSAS, it was found that a single load of OSA caused an abrupt increase in blood pressure (BP) (Apnea Surge in seconds), while multiple OSA episodes occurring nightly for 1-3 months led to a sustained elevation of BP during both nighttime and daytime. Epidemiological studies on 24-hour ambulatory BP measurements revealed that some hypertensive patients experienced elevated BP in the early morning (Morning Surge), which could be intensified by OSAS. The resonance of Apnea Surge in seconds and Morning Surge increases the risk of organ damage, triggers the cardiovascular events, and adversely affects the prognosis of hypertensive patients with OSAS.For ameliorating these risks, OSA should be treated with positive airway pressure properly.

Assessment of cognitive function and sleep-wake rhythms in community-dwelling older adults.

Disruption of the circadian rhythm and sleep-wake cycles is a consequence of aging and is associated with the cognitive decline and many neurodegenerative conditions. We investigated the bedtime, wake-up time, sleep timing (midpoint between bedtime and wake-up time), and sleep timing standard deviation (SD) using the actigraphy among 80 consecutive volunteers aged ≥ 60 years. Global cognitive function and executive function of detailed cognitive domains were evaluated using the mini-mental state examination (MMSE) and Wisconsin card sorting test (WCST) and subjective daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS). The category achievement (CA), total errors (TE), perseverative errors of Nelson (PEN), non-perseverative errors (NPE), and difficulties in maintaining set (DMS) on the WCST were significantly correlated with sleep timing SD (CA: r = - 0.276, p = 0.013, TE: r = 0.311, p = 0.005, PEN: r = 0.241, p = 0.032, NPE: r = 0.250, p = 0.025, DMS: r = 0.235, p = 0.036), but not with the MMSE score. Multiple regression analyses with the stepwise forward selection method including age, ESS score, bedtime, sleep timing, and sleep timing SD, revealed that the ESS score, and sleep timing SD were significant factors related to CA on the WCST (ESS score: ß = - 0.322, p = 0.004; sleep timing SD: ß = - 0.250, p = 0.022). Assessment of sleep-wake rhythms, daytime sleepiness, and cognitive function using the MMSE and WCST is valuable for the prediction of cognitive decline in the geriatric population.

Expression of a highly active catalase VktA in the cyanobacterium Synechococcus elongatus PCC 7942 alleviates the photoinhibition of photosystem II.

The repair of photosystem II (PSII) after photodamage is particularly sensitive to reactive oxygen species-such as H2O2, which is abundantly produced during the photoinhibition of PSII. In the present study, we generated a transformant of the cyanobacterium Synechococcus elongatus PCC 7942 that expressed a highly active catalase, VktA, which is derived from a facultatively psychrophilic bacterium Vibrio rumoiensis, and examined the effect of expression of VktA on the photoinhibition of PSII. The activity of PSII in transformed cells declined much more slowly than in wild-type cells when cells were exposed to strong light in the presence of H2O2. However, the rate of photodamage to PSII, as monitored in the presence of chloramphenicol, was the same in the two lines of cells, suggesting that the repair of PSII was protected by the expression of VktA. The de novo synthesis of the D1 protein, which is required for the repair of PSII, was activated in transformed cells under the same stress conditions. Similar protection of the repair of PSII in transformed cells was also observed under strong light at a relatively low temperature. Thus, the expression of the highly active catalase mitigates photoinhibition of PSII by protecting protein synthesis against damage by H2O2 with subsequent enhancement of the repair of PSII.

Poor sleep quality impairs cognitive performance in older adults.

The prevalence of insomnia increases with age. Short sleep duration is associated with deficits in cognitive performance. We hypothesized that short sleep duration and sleep quality influence cognitive performance in older adults. The study included 78 adults aged 60 years and over (72.2 ± 5.9 years). Total sleep time and sleep efficiency (total sleep time/time in bed × 100) were calculated using actigraphy. We evaluated cognitive performance with the continuous performance test-identical pairs and the number-back test. Sleep apnea was evaluated overnight with a portable home monitoring system. The accuracy of the 0-back test significantly decreased in participants with total sleep time less than 5 h compared with those with total sleep time greater than 7 h, but there was no significant difference in continuous performance test-identical pairs between the two groups. Participants with sleep efficiency <85% showed a significant decrease in 0- and 1-back test accuracy compared with those with sleep efficiency ≥85%. There were no significant differences in the accuracy of number-back tests and continuous performance test-identical pairs between apnea-hypopnea index ≥15 h(-1) and apnea-hypopnea index <15 h(-1) groups, or among lowest SpO2  ≥ 90%, lowest 80-90%, and lowest SpO2  < 80% groups. Age, total sleep time and sleep efficiency were significantly correlated with accuracy on the 0-back test. Age and sleep efficiency were significantly correlated with accuracy on the 1-back test. Multiple regression analysis revealed that total sleep time was independently correlated with accuracy on the 0-back test, while age was independently correlated with accuracy on the 1-back test. Our findings suggest that sleep duration and sleep quality may play a role in cognitive performance in older adults.

Comparison of oxygen desaturation patterns in children and adults with sleep-disordered breathing.

PURPOSE: Although the number of apnea-hypopnea episodes per hour apnea-hypopnea index (AHI) is typically used to evaluate sleep-disordered breathing (SDB) in adults, it does not provide an accurate characterization of SDB in children. We investigated differences in SDB patterns in children and adults to evaluate SDB severity in children. MATERIALS AND METHODS: Fifteen adults (mean age, 45.3 ± 8.4 years) and 15 children (mean age, 6.7 ± 3.9 years) with adenotonsillar hypertrophy underwent standard polysomnography. The change of oxygen saturation (ΔSpO2) was defined as the difference between baseline SpO2 during stable nighttime breathing and the lowest SpO2 accompanied by an apnea-hypopnea event. The number of apnea-hypopnea episodes was determined using two different criteria to define an episode (criterion 1: cessation of airflow for at least 10s; criterion 2: cessation of airflow for at least two consecutive breaths). RESULTS: Mean ΔSpO2 accompanied by obstructive apneas lasting ≤10 s was significantly greater in children than in adults, although there was no significant difference in the duration of apnea-hypopnea episodes. The slope of the regression line between ΔSpO2 and apnea-hypopnea duration in children was greater than in adults (P<0.005). AHI in children was higher when calculated using criterion 2 compared to criterion 1 (10.9 ± 9.4 vs. 6.5 ± 4.9/h, P=0.003). CONCLUSIONS: ΔSpO2 is a good indicator of SDB severity in children, and should therefore be considered in the diagnosis and treatment of pediatric SDB along with AHI.