Production of Lactobacillus brevis ProGA28 attenuates stress-related sleep disturbance and modulates the autonomic nervous system and the motor response in anxiety/depression behavioral tests in Wistar-Kyoto rats

AIMS

Many studies have reported that the production of Lactobacillus brevis is beneficial for sleep, but the underlying mechanism remains unclear. Other known beneficial effects of Lactobacillus brevis include improvement of anxious or depressive symptoms and better modulation of the autonomic nervous system, both of which impact sleep. In this study, we investigated whether the sleep benefit of Lactobacillus brevis was associated with the modulating effects on the autonomic nervous system and anxious/depressive symptoms.

MAIN METHODS

Wistar-Kyoto rats were fed the production of Lactobacillus brevis (ProGA28) for the last 2 weeks of treatment before being exposed to case exchange (stress-induced insomnia paradigm). Waking, quiet sleep, and paradoxical sleep states were defined based on polysomnographic measurements. Autonomic functioning was assessed by heart rate variability (HRV). A combined behavioral test was used to evaluate anxiety-like or depressive-like behaviors after the following 2 days.

KEY FINDINGS

In exposure to the dirty cage, the control group had significant prolongation of sleep latency, sleep loss during the first 2 h, and decreased parasympathetic activity and increased sympathetic activity during quiet sleep, which were significantly mitigated in the ProGA28 group. In behavioral tests, the ProGA28 group exhibited significantly less anxiety/depression-like motor responses in the elevated plus maze test, the forced swimming test, and the three-chamber social interaction test. Less initial sleep loss in the ProGA28 group was related to higher parasympathetic activity during quiet sleep, and shorter sleep latency in both groups was associated with longer time staying in the open arm in the elevated plus maze test.

SIGNIFICANCE

These findings suggest that L. brevis ProGA28 can attenuate stress-related sleep disturbance, which may be associated with increased parasympathetic activity and decreased anxiety-like behaviors.

Using a 360° Virtual Reality or 2D Video to Learn History Taking and Physical Examination Skills for Undergraduate Medical Students: Pilot Randomized Controlled Trial

BACKGROUND

Learning through a 360° virtual reality (VR) or 2D video represents an alternative way to learn a complex medical education task. However, there is currently no consensus on how best to assess the effects of different learning materials on cognitive load estimates, heart rate variability (HRV), outcomes, and experience in learning history taking and physical examination (H&P) skills.

OBJECTIVE

The aim of this study was to investigate how learning materials (ie, VR or 2D video) impact learning outcomes and experience through changes in cognitive load estimates and HRV for learning H&P skills.

METHODS

This pilot system-design study included 32 undergraduate medical students at an academic teaching hospital. The students were randomly assigned, with a 1:1 allocation, to a 360° VR video group or a 2D video group, matched by age, sex, and cognitive style. The contents of both videos were different with regard to visual angle and self-determination. Learning outcomes were evaluated using the Milestone reporting form. Subjective and objective cognitive loads were estimated using the Paas Cognitive Load Scale, the National Aeronautics and Space Administration Task Load Index, and secondary-task reaction time. Cardiac autonomic function was assessed using HRV measurements. Learning experience was assessed using the AttrakDiff2 questionnaire and qualitative feedback. Statistical significance was accepted at a two-sided P value of <.01.

RESULTS

All 32 participants received the intended intervention. The sample consisted of 20 (63%) males and 12 (38%) females, with a median age of 24 (IQR 23-25) years. The 360° VR video group seemed to have a higher Milestone level than the 2D video group (P=.04). The reaction time at the 10th minute in the 360° VR video group was significantly higher than that in the 2D video group (P<.001). Multiple logistic regression models of the overall cohort showed that the 360° VR video module was independently and positively associated with a reaction time at the 10th minute of ≥3.6 seconds (exp B=18.8, 95% CI 3.2-110.8; P=.001) and a Milestone level of ≥3 (exp B=15.0, 95% CI 2.3-99.6; P=.005). However, a reaction time at the 10th minute of ≥3.6 seconds was not related to a Milestone level of ≥3. A low-frequency to high-frequency ratio between the 5th and 10th minute of ≥1.43 seemed to be inversely associated with a hedonic stimulation score of ≥2.0 (exp B=0.14, 95% CI 0.03-0.68; P=.015) after adjusting for video module. The main qualitative feedback indicated that the 360° VR video module was fun but caused mild dizziness, whereas the 2D video module was easy to follow but tedious.

CONCLUSIONS

Our preliminary results showed that 360° VR video learning may be associated with a better Milestone level than 2D video learning, and that this did not seem to be related to cognitive load estimates or HRV indexes in the novice learners. Of note, an increase in sympathovagal balance may have been associated with a lower hedonic stimulation score, which may have met the learners' needs and prompted learning through the different video modules.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03501641; https://clinicaltrials.gov/ct2/show/NCT03501641.

Biomaterial-induced conversion of quiescent cardiomyocytes into pacemaker cells in rats

Pacemaker cells can be differentiated from stem cells or transdifferentiated from quiescent mature cardiac cells via genetic manipulation. Here we show that the exposure of rat quiescent ventricular cardiomyocytes to a silk-fibroin hydrogel activates the direct conversion of the quiescent cardiomyocytes to pacemaker cardiomyocytes by inducing the ectopic expression of the vascular endothelial cell-adhesion glycoprotein cadherin. The silk-fibroin-induced pacemaker cells exhibited functional and morphological features of genuine sinoatrial-node cardiomyocytes in vitro, and pacemaker cells generated via the injection of silk fibroin in the left ventricles of rats functioned as a surrogate in situ sinoatrial node. Biomaterials with suitable surface structure, mechanics and biochemistry could facilitate the scalable production of biological pacemakers for human use.

Long-term atomoxetine-oxybutynin combination use may be beneficial for the prevention of obstructive sleep apnea

One recent study showed that atomoxetine-oxybutynin combination (AOC) use is effective in reducing obstructive sleep apnea (OSA) severity. We used a nationwide database to examine the association between AOC use and the risk of OSA incidence. This retrospective cohort study used Taiwan's National Health Insurance Research Database between the years 2000 and 2015. The patients who used atomoxetine or oxybutynin were included as an exposed cohort. The exposed and unexposed groups were selected in a ratio of 1:3 with sex, age, and index year matching. We used the multivariate Cox proportional regression model to evaluate the association between AOC use and the risk of an incident diagnosis of OSA. The incidence rates of OSA in the exposed cohort (N = 8940) and the unexposed cohort (N = 26,820), were 21.92 and 22.93 per 100,000 person-years, respectively. The adjusted hazard ratio of oxybutynin use only and AOC with a treatment duration of ≥ 366 days were 0.307 (95% CI 0.204-0.995, P = 0.045) and 0.299 (95% CI 0.102-0.933, P = 0.002), respectively. Long-term atomoxetine-oxybutynin combination therapy may be beneficial to reduce the risk of obstructive sleep apnea. Further studies to examine these mechanisms are warranted.

Roles of cardiovascular autonomic regulation and sleep patterns in high blood pressure induced by mild cold exposure in rats

Increased blood pressure (BP) caused by exposure to cold temperatures can partially explain the increased incidence of cardiovascular events in winter. However, the physiological mechanisms involved in cold-induced high BP are not well established. Many studies have focused on physiological responses to severe cold exposure. In this study, we aimed to perform a comprehensive analysis of cardiovascular autonomic function and sleep patterns in rats during exposure to mild cold, a condition relevant to humans in subtropical areas, to clarify the physiological mechanisms underlying mild cold-induced hypertension. BP, electroencephalography, electromyography, electrocardiography, and core body temperature were continuously recorded in normotensive Wistar-Kyoto rats over 24 h. All rats were housed in thermoregulated chambers at ambient temperatures of 23, 18, and 15 °C in a randomized crossover design. These 24-h physiological recordings either with or without sleep scoring showed that compared with the control temperature of 23 °C, the lower ambient temperatures of 18 and 15 °C not only increased BP, vascular sympathetic activity, and heart rate but also decreased overall autonomic activity, parasympathetic activity, and baroreflex sensitivity in rats. In addition, cold exposure reduced the delta power percentage and increased the incidence of interruptions during sleep. Moreover, a correlation analysis revealed that all of these cold-induced autonomic dysregulation and sleep problems were associated with elevation of BP. In conclusion, mild cold exposure elicits autonomic dysregulation and poor sleep quality, causing BP elevation, which may have critical implications for cold-related cardiovascular events.

Difficulty in initiating sleep is associated with poor morning cardiovascular function

Insomnia is a risk factor for hypertension and cardiovascular events, and this association is strongest for sleep-onset insomnia. This study explored morning cardiovascular function in individuals with sleep-onset insomnia by analysing heart rate variability (HRV), blood pressure variability, and baroreflex sensitivity. Sleep quality of fifteen good sleepers and 13 individuals with sleep-onset insomnia was measured by overnight polysomnography, followed by continuous recordings of the participant's blood pressure and heart rate for 10 min immediately after they had woken up the following morning. After morning awakening (averaged time: 12.33 ± 10.48 min), a significantly reduced vagal tone assessed by HRV, including lower total power of HRV, lower high frequency of HRV, and elevated slopes of systolic as well as diastolic blood pressure in the morning with a blunted baroreflex sensitivity in the insomnia group were noted, compared to the control group. No differences in sympathetic-related activity were observed. The regulation of cardiovascular activity by the parasympathetic nervous system plays an important role in sleep-onset insomnia. Weak vagal modulation and blunted baroreflex sensitivity were evident in this insomnia subtype, which indicates that difficulty in initiating sleep can independently affect morning cardiovascular function.

Snoring Sound Characteristics are Associated with Common Carotid Artery Profiles in Patients with Obstructive Sleep Apnea

BACKGROUND

Obstructive sleep apnea (OSA) and snoring have been reported to be modifiable risk factors for thick carotid intima-media thickness (CIMT) and carotid atherosclerosis, which are closely linked to cardiovascular disease.

METHODS

This cross-sectional study prospectively recruited 70 participants with OSA and without a history of carotid artery disorder, who primarily sought surgical Intervention. OSA and snoring were assessed with the Epworth Sleepiness Scale, Snore Outcomes Survey, polysomnography, and snoring sound recording. The carotid arteries were evaluated with ultrasonography and divided into three types of carotid artery profiles (normal carotid artery, thick CIMT, or significant carotid atherosclerosis). Multivariate linear/logistic/categorical regressions were performed with the forward selection approaches/logistic least absolute shrinkage and selection operator, as appropriate.

RESULTS

Normalized snoring sound energy (301-850 Hz) was independently associated with the carotid intima-media thickness (regression coefficient [β] = 0.01, standard error [SE] = 0.004, P = 0.03; R ² = 0.067) and type of carotid profile (β = 0.40, SE = 0.09, P < 0.001; R ² = 0.156). Normalized snoring sound energy (4-300 Hz) (β = -0.10, SE = 0.04, P = 0.01) and female sex (β = 1.90, SE = 0.94, P = 0.04) were independently related to the presence of carotid stenosis (R ² = 0.159). The optimal regression model of the type of carotid artery profile included normalized snoring sound energy (301-850 Hz) (β = 0.33, SE = 0.14, P = 0.03), snoring time (β = 0.26, SE = 0.13, P = 0.047), female sex (β = 0.26, SE = 0.13, P = 0.047), and increased age (β = 0.20, SE = 0.10, P = 0.04) under the control of the Snore Outcomes Survey score, 3% oxygen desaturation index, snoring sound energy (4-1500 Hz), normalized snoring sound energy (851-1500 Hz), cigarette smoking, and hyperlipidemia (R ² = 0.427).

CONCLUSION

Our findings suggested that snoring sound characteristics are associated with carotid artery profiles among early OSA patients who cannot be noticed by ultrasound because organic changes of the carotid artery have not yet started. Future studies are warranted to verify the clinical significance of the results.

Disclosure of suboptimal health status through traditional Chinese medicine-based body constitution and pulse patterns

OBJECTIVES

Suboptimal health status (SHS) is a dynamic state wherein people have not been diagnosed with a disease but tend to develop diseases. People with SHS often experience fatigue and other nonspecific symptoms, which are related to a deviated body constitution in traditional Chinese medicine (TCM). However, the correlation between TCM constitution and SHS has not been adequately investigated. Furthermore, no study has explored the radial pulse analysis-an assistive objective indicator of TCM constitution-in healthy people and people with SHS.

DESIGN

A cross-sectional study.

SETTINGS/LOCATION

Center for Traditional Medicine, Taipei Veterans General Hospital, Taiwan.

SUBJECTS

Sixty-six adults (27 healthy participants and 39 participants with SHS) who were aged 20-39 years.

OUTCOME MEASURES

The body constitution questionnaire (BCQ) scores, suboptimal health status questionnaire-25 (SHSQ-25) scores, and radial pulse waves detected using sphygmography were recorded. Pulse wave analyses are presented as the ratio of frequency below 10 Hz to that above 10 Hz (SER10), which represent energy changes in organ blood flow.

RESULTS

Participants with SHS had significantly higher Yang-Xu, Yin-Xu, and stasis scores of BCQ compared with healthy participants. The SHSQ-25 scores of the participants with SHS were moderately correlated with their Yang-Xu, Yin-Xu, and stasis scores (r = 0.65, 0.66, and 0.72, respectively; all p < 0.001), but weak correlations were discovered for healthy participants. The participants with SHS had significantly higher SER10 at the left guan (the "liver" system in TCM) than did the healthy participants.

CONCLUSIONS

SHS is moderately correlated with TCM-based constitution and those with SHS had increased SER10 at the leftguan of the radial pulse.

Real-world evidence on the use of benzodiazepine receptor agonists and the risk of venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE) is a life-threatening disease, and some studies reported that benzodiazepine receptor agonist (BZRA) use could increase the risk of VTE, but this association lacks population-based evidence.

OBJECTIVES

To investigate the association between BZRA use and the risk of VTE.

PATIENTS/METHODS

A nested case-control study analyzing Taiwan's claims database was conducted of patients with at least one new BZRA prescription on record from January 1, 2002, to December 31, 2012. We included new users who did not have any BZRA prescriptions in the preceding 2 years and identified cases with VTE and disease risk score matched control subjects. We used a logistic regression model to investigate the association between BZRA exposure and the risk of VTE. The exposure duration, dose, and classes of BZRAs were comprehensively evaluated.

RESULTS

We identified 2800 VTE cases and 2800 matched controls. Current BZRA prescription (≤90 days) was associated with VTE occurrence (adjusted odds ratio [aOR]: 1.83; 95% confidence interval [CI], 1.62-2.06). The point estimates of benzodiazepine hypnotics (aOR: 2.00; 95% CI, 1.45-2.76) had a marginally higher risk of VTE than nonbenzodiazepine hypnotics (aOR: 1.39; 95% CI, 1.07-1.81). The VTE risk was increased with combination BZRA use, number of BZRA used, and a higher dose of BZRA. On examination of individual BZRA, the risk of VTE was higher with flunitrazepam use (aOR: 2.99; 95% CI, 1.43-6.28) than other BZRAs.

CONCLUSIONS

This study presents that current BZRA use may increase the risk of VTE. Also, benzodiazepine hypnotics, especially flunitrazepam, have a higher risk of VTE.

Voluntary exercise enhances hippocampal theta rhythm and cognition in the rat

Regular exercise promotes learning and memory functions. Theta activity is known to relate to various cognitive functions. An increase in theta power may be related to higher cognitive functioning and learning functions. However, evidence is lacking to directly confirm that exercise training can increase the theta activity and promote various cognitive functions simultaneously. We hypothesize that long-term voluntary exercise increases the activity of hippocampal theta rhythm and enhances memory behavior. We used the voluntary wheel running model and a training period of 8 weeks. We started the training when the rats were 12 weeks old. Before and after intervention, we performed a 24 -h electrophysiological recording and 8-arm radial maze test to analyze the hippocampal theta rhythm in awake stage, and spatial memory functions. We discovered that middle to high range frequency (6.5-12 Hz) of theta power was increased after exercise intervention. In addition, the working memory error of 8-arm radial maze test in the exercise group decreased significantly after the 8 weeks of treatment, and these reductions were negatively correlated with hippocampal theta activity. Our results demonstrate that 8-weeks voluntary exercise increases both hippocampal theta amplitude and spatial memory in the rats.

Implementation of Wireless Biosensor for Continuous EEG Monitoring in Neurological Intensive Care

Seizure is a common complication in a neurological intensive care unit (NICU) and it requires continuous electroencephalograms (EEG) monitoring. Implementation of EEG for each bed in a NICU is very expensive and require labor work for interpretation of EEG. To provide an affordable device of EEG in NICU, we developed a low-cost wireless biosensor, which utilized the current standard of the internet of things technology (IoT). In this study, we implement a wireless biosensor for continuous EEG monitoring in NICU and discuss its feasibility. To provide a low-cost EEG device, we embraced Bluetooth and mobile phone technology, which is convenient for implementation. We build a two-channel EEG biosensor, which utilizes Bluetooth to transmit the signal to mobile phones. Then, mobile phones use Wi-Fi technology to send data to the server. Additionally, we also developed a registry to organize the patient's EEG data. In six months research period, we have 65.8% of patients collected successfully. Using 2 channel-biosensor in NCU is feasible. It also develops a neuromedical database by collecting and monitoring physiological signals to develop future neuromedical research.

Behaviour consistency is a sensitive tool for distinguishing the effects of aging on physical activity

We attempted to establish a novel parameter of behaviour consistency to help determine the effect of age on physical activity. Using the speed of movement to quantify behaviour might not be sufficient to determine this effect. The slowing of motor activities that occurs with aging is related to the decline of the aging brain. Previous studies have found different running-related hippocampal theta rhythm responses in the aging and exercise model. Therefore, we hypothesized that a familiarity with the environment and physical strength affect behavioural consistency in rats during running exercises. For this study, we used a treadmill and 30-minute running test at constant speeds and compared changes in the triaxial accelerometer and hippocampal theta rhythm between adult and middle-aged rats. No significant differences in RR intervals, mean cross-correlations (MCCs), or the proportion of good correlation coefficient (PGCC) were observed between adult and middle-aged rats in awake states before running on the treadmill. The root mean square (RMS) of the triaxial acceleration vectors in middle-aged rats was higher than that in adult rats. In the treadmill running tests, the RMS observed in middle-aged rats was significantly lower than that observed in adult rats. MCC and PGCC, which indicate movement consistencies, were significantly higher in middle-aged rats than they were in adult rats during the entire running test. However, only the RMS of the adult rats showed a negative correlation with exercise duration. Both MCC and PGCC were positively correlated with exercise duration. By contrast, a similar phenomenon was not found in the changes or differences in hippocampal theta rhythms between these two groups. Therefore, we consider that the MCC and PGCC could distinguish age-related movement differences and indicate coordination/adaptation during exercise. Changes in physical activity and alterations in the hippocampal theta rhythm were not different between the groups.

Failure to de-arouse during sleep-onset transitions in the heart rates of individuals with sleep-onset insomnia

OBJECTIVE

Increased cardiovascular risk associated with sleep-onset insomnia has been reported, but the patterns of heart rate (HR) transitions during sleep onset in individuals with sleep-onset insomnia remain uncertain. This study explored the HR dynamics during objective and subjective sleep onset transitions among sleep-onset insomnia.

METHODS

Seventeen good sleepers and 17 individuals with sleep-onset insomnia had their night-time HR measured. HR and heart rate variability (HRV) were analyzed within 8-min periods of pre- and post-transition of stage N1, stage N2 and subjective sleep onset.

RESULTS

A significantly higher low-frequency percentage of HRV was observed in pre-N1 period among insomnia group, compared with good sleepers. Decline in HR begins in 160 s prior to N1 onset among good sleepers, whereas the HRs of insomnia group were reduced only after N1 onset in comparison to their HRs at the time of N1 onset. The good sleepers and insomnia group both had their HRs dropped to a level comparable to their HRs at respective stage N2 onset at 220 s and 80 s prior to N2 onset. No differences in HR was found during subjective sleep onset transition in both groups.

CONCLUSION

During the wake-to-sleep transition, a low and stable HR was observed before cortical alternations in good sleepers; however, a consistently high HR until N1 onset was shown among sleep-onset insomnia. This finding suggests a state-dependent and failure to de-arouse from the high arousal level of wakefulness into light sleep is associated with sleep initiation difficulty.

Autonomic reactivity during reading of a somatic distress script in patients with somatic symptom disorder

OBJECTIVE

The relationship between resting-state heart rate variability (HRV) and somatic symptom disorder (SSD) has been explored in several studies. We planned to examine HRV during the performance of psychological tasks, and assumed that it could be applied for the diagnosis of SSD.

METHODS

Fifty-three patients with SSD and 52 healthy controls were recruited. Demographic and psychological data were collected. Subjects' HRV was measured over five 5-minute blocks during which they viewed different scripts (resting state; health anxiety; somatic distress; depression; neutral topic). After each block they completed a self-assessment manikin. Generalized estimated equation analysis was used to analyze the impact of mental scripts, SSD and sex on physiological and psychological indicators.

RESULTS

In men there was a script*SSD interaction concerning high-frequency power (HF) involving the neutral script; SSD men showed significantly higher HF than healthy men when viewing neutral script. In women there were script*SSD interactions with respect to low-frequency power (LF) and HF involving the somatic distress script and a script*SSD interaction with respect to LF and emotional valence involving the neutral script; SSD women revealed significantly lower LF and HF than healthy women when viewing somatic distress script, they also showed significantly lower LF and higher valence than healthy ones during neutral script. The somatic distress script*SSD interaction still influenced LF and HF in women after adjusting for potential confounders.

CONCLUSION

In women cue-specific HRV is a better method of differentiating people with SSD from healthy individuals than resting-state HRV.

TRIAL REGISTRATION INFORMATION

The Research Ethics Committee of National Taiwan University Hospital approved this study (approval number: 201410050RINB).

The Risk of Hospitalization for Motor Vehicle Accident Injury in Narcolepsy and the Benefits of Stimulant Use: A Nationwide Cohort Study in Taiwan

STUDY OBJECTIVES

To examine the risk of hospitalization for motor vehicle accident injury (MVAI) in patients with narcolepsy and the effects of stimulant use on MVAI occurrence in patients with narcolepsy.

METHODS

This is a population-based, retrospective cohort study using Taiwan's National Health Insurance Research Database between 2000 and 2013. We included patients with narcolepsy based on the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, 347. The case and matched control participants were selected in a ratio of 1:3, and the traffic accident (ICD-9-CM codes: E810-E819) plus injury codes (ICD-9-CM codes: 800.xx-999.xx) due to MVAI following hospitalization were used for the study outcome. The type of injury, causes, intentionality, and the effects of stimulant use on patients with narcolepsy were also assessed.

RESULTS

A total of 1,316 participants were enrolled, including 329 participants with narcolepsy and 987 participants without narcolepsy. During a 14-year follow-up period, a total of 104 participants had MVAI, of whom 47 (1,559.54 per 100,000 person-years) belonged to the narcolepsy cohort and 57 (556.21 per 100,000 person-years) to the non-narcolepsy cohort. After adjusting for covariates, the risk of hospitalization for MVAI among participants with narcolepsy was still significantly higher than those without narcolepsy (adjusted hazard ratio = 6.725; 95% confidence interval = 4.421-10.231; P < .001). The use of modafinil or methylphenidate, as monotherapy or combined treatment, was associated with a lower risk of MVAI in the narcolepsy cohort.

CONCLUSIONS

Patients with narcolepsy may have a higher risk of hospitalization for MVAI and stimulant use could mitigate such risk.

Short Sleep Duration Is Associated With Increased Serum Homocysteine: Insights From a National Survey

STUDY OBJECTIVES

Both short sleep duration and increased serum homocysteine levels are associated with cardiovascular events. However, research on the relationship between sleep duration and serum homocysteine levels is sparse. The aim of this study is to examine the association between sleep duration and serum homocysteine levels from a national database.

METHODS

In total, 4,480 eligible participants older than 20 years who had serum homocysteine data and reported sleep duration were enrolled from the US National Health and Nutrition Examination Survey of 2005 to 2006. The association between sleep duration and serum homocysteine levels was analyzed using multivariate regression models for covariate adjustment.

RESULTS

Serum homocysteine level was lowest in individuals with a sleep duration of 7 hours and increased in those with both shorter and longer self-reported total sleep time (groups were categorized into ≤ 5 hours, 6 hours, 7 hours, 8 hours, and ≥ 9 hours). After adjustment for covariates, those in the group sleeping ≤ 5 hours had significantly higher serum homocysteine levels than the reference group (sleep duration of 7 hours). In subgroup analyses by sex, body mass index (BMI), and ethnicity, the association between short sleep duration (≤ 5 hours) and higher serum homocysteine levels persisted in women, individuals with obesity (BMI ≥ 30 kg/m²), and non-Hispanic whites.

CONCLUSIONS

This study highlighted that short sleep duration was associated with higher serum homocysteine levels in women, individuals with obesity (BMI ≥ 30 kg/m²), and non-Hispanic whites; this finding might suggest increased vulnerability to cardiovascular risk or other atherothrombotic events in these groups in the context of short sleep.

Effects of long-term exercise on arrhythmogenesis in aged hypertensive rats

Chronic hypertension is a multifactorial disease that is highly associated with cardiovascular disorders. Physical activity, such as long-term exercise, is advocated as a treatment for hypertension, but the responses of different age groups to long-term exercise are unknown. We used aged spontaneous hypertensive rats (SHRs, 80 weeks old) to test the hypothesis that long-term exercise compensated for deficient autonomic control and reduced susceptibility to ventricular tachycardia (VT) and ventricular fibrillation (VF) in this animal model. The aged SHRs were divided into control and voluntary exercise groups. Ambulatory electrocardiography was recorded for the heart rate variability (HRV) analysis. Programmed stimulation was applied to exposed hearts to induce ventricular arrhythmia in situ. Then, the hearts were isolated for an optical mapping study. The results showed that increased HRV indices were broadly related to vagal dominance in the high-intensity exercise group. Exercise altered the electrical propagation dynamic properties, such as the action potential duration restitution (APDR). Furthermore, the VF inducibility decreased with increased exercise intensity. Taken together, our results suggest that long-term exercise reduces the risk of arrhythmogenesis in aged SHRs through enhanced vagal control and stabilized electrical dynamics.

Effects of depression and melatonergic antidepressant treatment alone and in combination with sedative-hypnotics on heart rate variability: Implications for cardiovascular risk

OBJECTIVES

To examine heart rate variability (HRV) in unmedicated patients with major depressive disorder (MDD) and its changes after treatment with agomelatine alone and in combination with sedative-hypnotics.

METHODS

We recruited 152 physically healthy, unmedicated patients with MDD and 472 age- and sex-matched healthy volunteers. Frequency-domain measures of HRV were obtained during enrolment for all participants and again for MDD patients after 6 weeks of treatment with agomelatine alone and combining sedative-hypnotics.

RESULTS

Compared to the controls, unmedicated patients exhibited significantly lower mean R-R intervals, low-frequency (LF) HRV, and high-frequency (HF) HRV, but higher LF/HF ratios. Fifty-six and 49 patients successfully completed agomelatine monotherapy and the combination therapy of agomelatine and sedative-hypnotics, respectively. Between-group analyses showed significant treatment-by-group interactions for LF-HRV, HF-HRV and LF/HF ratio. The results showed a significant increase in HF-HRV after agomelatine monotherapy, a significant decrease in LF-HRV and HF-HRV, and a increase in the LF/HF ratio after combination therapy.

CONCLUSIONS

MDD patients had reduced HRV, and the patterns of HRV changes differed between patients treated with agomelatine alone and in combination with sedative-hypnotics. Clinicians should consider HRV effects when adding sedative-hypnotics to agomelatine, which is important for depressed patients who already have decreased cardiac vagal tone.

Influence of Accelerometer Placement and/or Heart Rate on Energy Expenditure Prediction during Uphill Exercise

Studies using a triaxial accelerometer and heart rate (HR) simultaneously for estimating energy expenditure (EE) during uphill exercise are rare. Exploring the optimal location for placing the accelerometer for predicting EE during uphill exercise is essential. Sixteen healthy male participants (M ± SEM; age 25.00 ± 0.61 years; body weight 74.13 ± 2.51 kg; body height 1.74 ± 0.01 m; body mass index 24.30 ± 0.63 kg/m²) exercised on a treadmill under 12 conditions (4 speeds and 3 gradients) on 3 days. Triaxial accelerometers, an HR recorder, and a metabolic measurement system were simultaneously used. Accelerometer outputs from various anatomical locations (upper arm, chest, lower back, waist, thigh, and instep) showed significant positive correlations with EE (0.819, 0.846, 0.816, 0.820, 0.672, and 0.669, respectively; p < .05). The linear regression equation for changes in HR showed the highest coefficient of determination (r²) of .837 with 87.9% reliability. When the HR signal was included, the r² value (> .842) and reliability (87.9%) between the accelerometer outputs and EE improved. Accelerometer outputs from the waist position alone provide highly accurate EE values. Using both accelerometer outputs and HR for EE estimation during uphill exercise is feasible and improves the accuracy of EE prediction.

Incorporation of Mobile Application (App) Measures Into the Diagnosis of Smartphone Addiction

OBJECTIVE

Global smartphone expansion has brought about unprecedented addictive behaviors. The current diagnosis of smartphone addiction is based solely on information from clinical interview. This study aimed to incorporate application (app)-recorded data into psychiatric criteria for the diagnosis of smartphone addiction and to examine the predictive ability of the app-recorded data for the diagnosis of smartphone addiction.

METHODS

Smartphone use data of 79 college students were recorded by a newly developed app for 1 month between December 1, 2013, and May 31, 2014. For each participant, psychiatrists made a diagnosis for smartphone addiction based on 2 approaches: (1) only diagnostic interview (standard diagnosis) and (2) both diagnostic interview and app-recorded data (app-incorporated diagnosis). The app-incorporated diagnosis was further used to build app-incorporated diagnostic criteria. In addition, the app-recorded data were pooled as a score to predict smartphone addiction diagnosis.

RESULTS

When app-incorporated diagnosis was used as a gold standard for 12 candidate criteria, 7 criteria showed significant accuracy (area under receiver operating characteristic curve [AUC] > 0.7) and were constructed as app-incorporated diagnostic criteria, which demonstrated remarkable accuracy (92.4%) for app-incorporated diagnosis. In addition, both frequency and duration of daily smartphone use significantly predicted app-incorporated diagnosis (AUC = 0.70 for frequency; AUC = 0.72 for duration). The combination of duration, frequency, and frequency trend for 1 month can accurately predict smartphone addiction diagnosis (AUC = 0.79 for app-incorporated diagnosis; AUC = 0.71 for standard diagnosis).

CONCLUSIONS

The app-incorporated diagnosis, combining both psychiatric interview and app-recorded data, demonstrated substantial accuracy for smartphone addiction diagnosis. In addition, the app-recorded data performed as an accurate screening tool for app-incorporated diagnosis.

Changes in Sleep Architecture under Sustained Pain in Adult Male Rats Subjected to Neonatal Short-Lasting Local Inflammatory Insult

Neonatal, short-lasting, local, nociceptive insult by carrageenan can cause long-term alterations in somatosensory and neurohumoral systems. We previously revealed hyporesponsiveness of the autonomic nervous system (ANS) after painful stimulation of adult rats in a neonatal carrageenan-induced pain model. Sleep disturbance has been highly correlated with pain and ANS activity. In the present study, adult rats that had received an intraplantar injection of carrageenan on postnatal day 1 were investigated to determine if there were alterations in their sleep architecture upon the stimulation of pain. Polysomnographic and heart rate variability recordings were carried out, with a wireless transmission of data, for 24 h under baseline conditions and after an intraplantar injection of complete Freund's adjuvant to induce sustained nociception. Increased active awake (AW) and decreased quiet sleep (QS) and paradoxical sleep (PS) times were noted in the control animals. In the carrageenan-treated rats, the AW time increased but with decreased alertness, as revealed by decreases in beta and increases in theta power. The QS time did not decrease. The PS time decreased during the first 12 h, then increased during the following 12 h, suggesting an early rebound of formerly deprived PS time. Sympathetic activation under sustained pain was not apparent in any stage of sleep in carrageenan-treated rats and was even suppressed in AW time. An impaired sympathetic reaction to pain may have contributed to the atypical changes in sleep architecture in these rats. In conclusion, pain in early life has a long-term effect on the cardiovascular-autonomic-electroencephalographic responses to pain later in life. The physiological relevance of these results remains undetermined.