Background: Sleep apnea syndrome (SAS) is accompanied by decreased alveolar ventilation due to upper airway stenosis and obstruction during sleep. This in turn induces a combination of hypoxemia and hypercapnia, a state in which the arterial partial pressure of carbon dioxide can be used as a key index for ascertaining patient condition and clinical course under treatment. Patients with SAS are also suspected to exhibit alveolar hypoventilation when awake. To thoroughly evaluate patients in an awake state at SAS diagnosis or at the start of treatment, we non-invasively measured the arterial partial pressure of carbon dioxide and investigated the usefulness of this approach.

　Methods: Using the TOSCA 500^TM a device for measurement of partial pressure of arterial transcutaneous carbon dioxide (PtcCO₂), we determined PtcCO₂ and investigated its correlation with the severity of SAS on initial examination in an awake state.

　Results: PtcCO₂ correlated weakly but non-significantly with severity and BMI, and was maintained within normal range even in severe cases.

　Conclusion: Severe SAS patients keep PtcCO₂ within normal range.

　Taurine (2-aminoethanesulfonic acid) is a sulfur-containing amino acid widely distributed in mammalian tissues. Although taurine is structurally analogous to the neurotransmitter gammaaminobutyric acid, suggesting that it may promote neuroendocrine activity, its role in promoting psychological stress in human subjects remains unelucidated. To this end, we aimed to determine the impact of a single oral dose of taurine on psychological stress induced by a calculation task. Healthy adult male university students (n ＝ 20) participated in a double-blinded placebocontrolled crossover trial. On day 1 of the experiment, participants ingested 3 g of taurine or 1g of dextrin (placebo). After a 15-min rest period, each participant was challenged with two calculation tasks, each lasting for a period of 15 min and separated by a 5-min rest period. In the second part of the experiment, participants ingested 1 g of the dextrin placebo and were asked to remain seated, with no specific tasks provided (control). We collected saliva samples from each participant before and after the experimental trials. The levels of salivary amylase activity increased significantly in response to the dextrin ingestion in both the placebo (p＜0.01) and control (p＜0.05) settings but not in response to taurine ingestion. The concentration of salivary chromogranin A (CgA) decreased significantly in response to taurine ingestion (p ＜ 0.01) but not in response to the dextrin ingestion in both the placebo and the control experiments. The changes in amylase activity (placebo＞control＞taurine) suggested that the increase in amylase activity that was amplified by the calculation task was suppressed by taurine ingestion. Similarly, CgA concentration in saliva from participants in the control trial exhibited a decrease, but this was increased in response to the calculation tasks (placebo). Taurine ingestion not only suppressed this increase but also amplified its decrease. Collectively, our results indicated that taurine ingestion suppressed the increase in the amylase activity and the decrease in CgA concentration in saliva in response to a calculation task. This finding is consistent with previous reports indicating that taurine can activate inhibitory signals to suppress adrenergic stimuli.

　Objective: It has been reported that increasing body temperature in the elderly confers clinical benefits such as activation of the immune system. The purpose of this study was to investigate the effects of short bouts of exercise over a protracted period on body temperature in the elderly.

　Methods: A total of 88 elderly participants were required to exercise for short bouts twice a week over a period of 2 years. The participants were divided into a below normal body temperature (n＝60) and an above normal body temperature group (n ＝ 28), with the baseline temperature set at 36.3°C.

　Results: In the below normal body temperature group, body temperature showed a significant increase after 2 years (36.05 ± 0.12°C to 36.29 ± 0.12°C, p ＜ 0.0001), while no significant change was observed in the normal body temperature group (36.34 ± 0.07°C from 36.37 ± 0.13°C,). A significant negative relationship was observed between change in body temperature and body temperature at the start of training (r＝ -0.69, p＜0.001). Multivariate analysis revealed that increase in body temperature was the factor most closely associated with decrease in the frequency of the common cold.

　Conclusion: Short bouts of exercise over a protracted period increased body temperature and decreased the frequency of colds in the elderly, especially in those with lower baseline body temperatures.

　Background：Clinical biomarkers predictive of postoperative delirium remain to be identified. Such biomarkers would aid in the planning of nursing care during the postoperative recovery period.

　Objectives: The purpose of this study was to determine whether postoperative delirium was associated with serum BDNF or proBDNF levels in patients undergoing abdominal surgery.

　Methods: Blood samples were collected from patients who had undergone abdominal surgery on the morning of postoperative day 1. Serum concentrations of BDNF and proBDNF in these samples were determined by ELISA.

　Results: Postoperative delirium developed in 4 of the patients. The results of ELISA revealed no statistically significant difference in concentrations of BDNF or proBDNF between samples from patients with or without postoperative delirium. A marked increase was observed in proBDNF levels in the samples from 2 of the 4 cases of postoperative delirium. A marked increase in proBDNF concentration and a decrease in potassium were observed in one case of hypoactive delirium.

　Conclusions: Examination of the relationship between serum BDNF or proBDNF level and the presence or absence of delirium on postoperative day 1 in 31 Japanese patients who underwent abdominal surgery revealed three findings: first, in patients with delirium, there was no change in BDNF concentration, but proBDNF concentration showed a tendency to increase; second, postoperative serum proBDNF levels were negatively correlated with potassium levels; third, hypoactive delirium tended to be associated with hypokalemia.

　Background: Clinical trials have shown efficacy and safety of direct oral anticoagulants (DOAC) comparable with that of warfarin in preventing stroke in patients with non-valvular atrial fibrillation (AF). However, postmarketing surveillance showed that numerous patients received “off-label”under-dosing of DOAC.

Methods: Between 2012 and 2015, consecutive AF patients newly initiated on rivaroxaban with preserved renal function were evaluated and prospectively followed until death or last follow-up. Patients were divided into two groups; taking rivaroxaban 15 mg (standard dose) and 10 mg (“off-label”under-dose). Primar y outcome was cardiovascular events (embolic events or cardiovascular death) and secondar y outcome was hemorrhage. Cox proportional hazards modeling was used to assess independent risk factors for events.

Results: Of 300 non-valvular AF patients (68 ± 10 years old, 22 ％ “off-label”under-dose), 13 (4.3％) had cardiovascular events and 22 (7％) had hemorrhagic events during mean follow-up of 13 ± 11 months. In the multivariable Cox proportional hazards model, “off-label”under-dosing of rivaroxaban carried significant independent risk of cardiovascular events but not hemorrhagic events.

Conclusion: In nonvalvular AF with preserved renal function, “off-label”under-dosing of rivaroxaban carries increased risk of cardiovascular events, but do not prevent hemorrhagic events.