Advanced emergency braking system reduces the risk of motor vehicle collisions caused by falling asleep while driving in patients with untreated obstructive sleep apnea.

Obstructive sleep apnea leads to excessive daytime sleepiness and cognitive dysfunction, which are risk factors for motor vehicle collisions. We aimed to clarify if vehicles with an advanced emergency braking system could reduce motor vehicle collisions caused by falling asleep while driving among patients with untreated obstructive sleep apnea. We enrolled patients with untreated obstructive sleep apnea who underwent polysomnography. The questionnaires included the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, history of drowsy driving accidents, and use of an advanced emergency braking system. Multivariate analysis was performed, and odds ratios and 95% confidence intervals were calculated. This study included 1097 patients (mean age, 51.2 ± 12.9 years). Collisions caused by falling asleep while driving were recorded in 59 (5.4%) patients, and were more frequently observed in vehicles without an advanced emergency braking system (p = 0.045). Multivariate analysis showed that these collisions were associated with use of an advanced emergency braking system (odds ratio [95% confidence interval]: 0.39 [0.16-0.97], p = 0.04), length of driving (2.79 [1.19-6.50], p = 0.02), total sleep time (2.40 [1.62-3.55], p < 0.0001), sleep efficiency (0.94 [0.90-0.98], p = 0.003) and periodic limb movement index (1.02 [1.01-1.03], p = 0.004). The collision risk caused by falling asleep while driving in vehicles with an advanced emergency braking system was significantly lower. This study indicates that advanced emergency braking systems may be a preventive measure to reduce motor vehicle collisions among patients with untreated obstructive sleep apnea.

Nocturnal hypoxemia is related to morning negative affectivity in untreated patients with severe obstructive sleep apnea.

The relationship between sleep apnea and morning affectivity remains unclear. We aimed to clarify how sleep disturbance in patients with obstructive sleep apnea (OSA) influences their affectivity. The enrolled participants underwent the Positive and Negative Affect Schedule on their beds immediately before and after overnight polysomnography. Thirty patients with OSA were divided into two groups according to the apnea-hypopnea index (AHI): mild to moderate OSA (5 ≤ AHI < 30/h) and severe OSA (AHI ≥ 30/h) groups. Additionally, 11 healthy participants (AHI < 5/h) were included as the control group. No independent association was found between affectivity and OSA severity markers in the whole population; however, the severe OSA group had a significantly higher cumulative percentage of sleep time at saturations < 90% (CT90) and worsened morning negative affectivity. Multiple regression analysis showed that CT90 was an independent factor for increasing negative affectivity in the severe OSA group (p = 0.0422). In patients with OSA, the receiver operating characteristic curve analysis showed that the best cutoff value for CT90 for predicting no decrease in negative affectivity after sleep was 1.0% (sensitivity = 0.56, specificity = 0.86); the corresponding area under the curve was 0.71. Worsening of negative affectivity in the morning was influenced by nocturnal hypoxemia in patients with severe OSA.

Effects of Continuous Positive Airway Pressure Therapy on Nocturnal Blood Pressure Fluctuation Patterns in Patients with Obstructive Sleep Apnea.

This retrospective study was designed to evaluate the effects of continuous positive airway pressure (CPAP) therapy, a well-established treatment for obstructive sleep apnea (OSA), on nocturnal blood pressure fluctuations (NBPFs) during rapid eye movement (REM) and non-REM sleep, and to evaluate the NBPF patterns in patients with OSA. We included 34 patients with moderate-to-severe OSA who underwent polysomnography using pulse transit time before and at 3−6 months after CPAP therapy. Nocturnal BP and NBPF frequency in REM and non-REM sleep were investigated, as well as NBPF pattern changes after receiving CPAP therapy. CPAP therapy resulted in significant reductions in the apnea−hypopnea index (AHI), arousal index, nocturnal systolic and diastolic BP, and NBPF frequency in REM and non-REM sleep (all p < 0.01). A higher AHI before CPAP resulted in lower nocturnal systolic BP (r = 0.40, p = 0.019) and NBPFs (r = 0.51, p = 0.002) after CPAP. However, 58.8% of patients showed no change in NBPF patterns with CPAP therapy. CPAP therapy significantly improved almost all sleep-related parameters, nocturnal BP, and NBPF frequency in REM and non-REM sleep periods, but NBPF patterns showed various changes post-CPAP therapy. These results suggest that factors other than OSA influence changes in NBPF patterns.

Efficacy of a Combination Therapy for Difficulties Waking Up in Non-School-Attending Students.

School non-attendance due to difficulties waking up is increasing in Japan, and affected students are commonly diagnosed with orthostatic dysregulation (OD); however, OD-associated sleep problems are overlooked. To date, no sleep-medicine-based treatment for wake-up difficulties in non-school-attending students has been established. This study aimed to assess the efficacy of a novel combination therapy for these students. We assessed the combined effect of sleep hygiene guidance, low-dose aripiprazole administration (3 mg/day), and blue-light exposure on wake-up difficulty in 21 non-school-attending teenage patients. The patients were evaluated using sleep studies and questionnaires before and after treatment. The average subjective total sleep time calculated from sleep diaries before treatment in the patients was 10.3 h. The therapy improved wake-up difficulty by 85.7% and further improved school non-attendance by 66.7%. The subjective sleep time significantly decreased by 9.5 h after treatment (p = 0.0004). The self-rating Depression Scale and mental component summary of the 36-item Short-Form Health Survey significantly improved after treatment (p = 0.002 and p = 0.01, respectively). Wake-up difficulties were caused by the addition of a delayed sleep phase to the patients' long sleep times. The novel combination therapy was effective in improving wake-up difficulty and mental quality of life in non-school-attending teenage students.

Prospective, Multicenter, Cross-Sectional Survey on Dry Eye Disease in Japan.

INTRODUCTION: Dry eye disease (DED) is commonly encountered in eye clinics and hospitals, and it is therefore very important to understand DED prevalence in outpatients. METHODS: A multicenter, hospital-based cross-sectional study was conducted among outpatients in Japan to ascertain DED prevalence and relationships between DED and patient profiles, including eye disease, DED diagnosis history, and surgical history. DED was diagnosed according to diagnostic criteria of the Asia Dry Eye Society. Patient self-assessment of DED-related subjective symptoms was conducted using the 5-Item Dry Eye Questionnaire (DEQ-5). Tear break-up time was evaluated in subjective symptom-positive patients. RESULTS: The prevalence of DED was 55.7% in 990 patients (mean age 69.1 ± 13.4 years), DED was commonly experienced in combination with other ocular diseases. In revisiting patients, 15.2% had not previously been diagnosed as DED, and their total DEQ-5 scores were higher than those of patients who had undergone DED treatment. CONCLUSION: This study revealed that more than half of the outpatients had DED. Among revisiting patients, there were many "hidden" DED patients who had not been diagnosed with DED in the past. There is a high likelihood of finding DED comorbidity in patients with other eye diseases in eye clinics and hospitals. FUNDING: Santen Pharmaceutical Co., Ltd. TRIAL REGISTRATION: UMIN Clinical Trials Registry Identifier, UMIN000035506.

Self-oscillating polymer brushes.

An autonomous functional surface has been designed by using self-oscillating polymers that convert the chemical energy of the Belousov-Zhabotinsky reaction into conformational changes of the polymer chains (see picture: red: hydrophobic/collapsed, green: hydrophilic/extended). Self-oscillating polymer brushes were grafted onto the inner surface of a glass capillary, and autonomous propagation of a chemical wave was observed.

Self-oscillating surface of gel for autonomous mass transport.

As a novel biomimetic gels deffering from conventonal stimuli-responsive polymer gels, we have developed a "self-oscillating" gel that swells and deswells periodically under constant condition without on-off switching of external stimuli. The gel is composed of poly(N-isopropylacrylamide) to which the catalyst of the oscillating chemical reaction, called Belousov-Zhabotinsky reaction, is covalently immobilized. The chemical oscillation is converted to the mechanical oscillation of the gel through the change in hydrophilicity of polymer chains with the redox changes of the immobilized catalyst. By utilizing the self-oscillating gel, several kinds of functional material systems such as biomimetic actuators, etc. are expected. Here we review a potential application to functional surface to realize autonomous mass-transport by utilizing the peristaltic motion of the gel. With the propagation of the chemical wave, the loaded cargo is autonomously transported on the surface. In order to fabricate the self-driven gel conveyer for a wider use including biomedical applications, the interactions between the self-oscillating gel and the loaded gel cargo were investigated and their influence on the transport phenomena were evaluated.

Self-driven gel conveyer: effect of interactions between loaded cargo and self-oscillating gel surface.

A "self-oscillating" gel that swells and deswells periodically under constant conditions is developed as a novel biomimetic gel differing from conventional stimuli-responsive polymer gels. By utilizing the peristaltic motion of the self-oscillating gel, autonomous mass-transport systems can be realized. With the propagation of the chemical wave, the loaded gel cargo is autonomously transported by rotating on the surface. To apply the self-driven gel conveyer to a wider range of uses, it is important to investigate the influence of the physical interaction between the self-oscillating gel and the loaded cargo on its transporting ability. Here, the effect of the interaction is evaluated by using several kinds of gel cargo with varying charge states, hydrophilicities, and surface roughnesses.

Self-oscillating gel as novel biomimetic materials.

Stimuli-responsive polymers and their application to biomaterials have been widely studied. On the other hand, as a novel biomimetic polymer, we have been studying the polymer with an autonomous self-oscillating function by utilizing oscillating chemical reactions. So far, we succeeded in developing a novel self-oscillating polymer and gels by utilizing the oscillating reaction, called the Belousov-Zhabotinsky (BZ) reaction, which is recognized as a chemical model for understanding several autonomous phenomena in biological systems. The self-oscillating polymer is composed of poly(N-isopropylacrylamide) (PNIPAAm) network in which the catalyst for the BZ reaction is covalently immobilized. Under the coexistence of the reactants, the polymer undergoes spontaneous cyclic soluble-insoluble changes or swelling-deswelling changes (in the case of gel) without any on-off switching of external stimuli. In this paper, our recent studies on the self-oscillating polymer gels and the design of functional material systems using the polymer are summarized.

Design of a mass transport surface utilizing peristaltic motion of a self-oscillating gel.

Novel conveyer gels exhibiting autonomous peristaltic motion without external stimuli were prepared by copolymerizing temperature-responsive N-isopropylacrylamide (NIPAAm), ruthenium tris(2,2'-bipyridine) (Ru(bpy)(3)) as the catalyst for the Belousov-Zhabotinsky (BZ) reaction, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS). When the gel was immersed in the catalyst-free BZ solution, the BZ reaction occurred in the gel and the chemical wave propagated followed by the peristaltic motion of the gel. In this study, we investigated the influence of the AMPS feed ratio on the network structure and the swelling-deswelling properties of the poly(NIPAAm-co-Ru(bpy)(3)-co-AMPS) gels. The gel had a microphase-separated structure when the AMPS feed ratio was less than 5 mol % due to the effect of the poor solvent in the polymerization process. On the other hand, when the AMPS feed ratio is more than 10 mol %, the gel is a homogeneous structure. The microphase-separated structure highly improved the swelling-deswelling kinetics and generated a swelling-deswelling amplitude of more than 10% of the gel thickness, which was approximately 10 times larger than that of the gel with a homogeneous network structure. Further, we attempted to transport an object by utilizing the peristaltic motion of poly(NIPAAm-co-Ru(bpy)(3)-co-AMPS) gels. A cylindrical poly(acrylamide) (PAAm) gel was transported on the gel surface with the propagation of the chemical wave when the AMPS feed ratio was low (less than 2.5 mol %). We have proposed a model to describe the mass transport phenomena based on the Hertz contact theory, and the relation between the transportability and the peristaltic motion was discussed. It was found that the microphase-separated structure of the gel had an important role for mass transport phenomena.