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Recent evidence suggests that obstructive sleep apnea (OSA) may increase the risk of Alzheimer´s disease (AD), with the latter promoting alterations in brain tissue stiffness, a feature of ageing. Here, we assessed the effects of age and intermittent hypoxia (IH) on brain tissue stiffness in a mouse model of OSA. Two-month-old and 18-month-old mice (N=10 each) were subjected to IH (20% O 2 40 s – 6% O 2 20 s) for 8 weeks (6 h/day). Corresponding control groups for each age were kept under normoxic conditions in room air (RA). After sacrifice, the brain was excised and 200-micron coronal slices were cut with a vibratome. Local stiffness of the cortex and hippocampus were assessed in brain slices placed in an Atomic Force Microscope. For both brain regions, the Young's modulus (E) in each animal was computed as the average values from 9 force-indentation curves. Cortex E mean (±SE) values were 442±122 Pa (RA) and 455±120 (IH) for young mice and 433±44 (RA) and 405±101 (IH) for old mice. Hippocampal E values were 376±62 (RA) and 474±94 (IH) for young mice and 486±93 (RA) and 521±210 (IH) for old mice. For both cortex and hippocampus, 2-way ANOVA indicated no statistically significant effects of age or challenge (IH vs. RA) on E values. Thus, neither chronic IH mimicking OSA nor ageing up to late middle age appear to modify local brain tissue stiffness in otherwise healthy mice. [ABSTRACT FROM AUTHOR]

Abstract: Background: Obstructive sleep apnea is common in patients waiting for bariatric surgery (BS). International consensuses have recommended assessment of obstructive sleep apnea in the preoperative evaluation to avoid perioperative complications. Polysomnography is the standard diagnostic method but is expensive and time-consuming. The aim of our study was to detect those patients who merit treatment before BS using a simple predictor model. The study was conducted at 3 university hospitals (Hospital de Bellvitge, Hospital de la Santa Creu i Sant Pau, Hospital Clinic de Barcelona). Methods: A prospective cross-sectional study was conducted of 136 consecutive bariatric subjects. The outcome variable was severe obstructive sleep apnea, defined as an apnea-hypoapnea index of ≥30 events/hr by polysomnography. The predictors evaluated were anthropometric and clinical in the first model, with an oxygen desaturation index of ≥3% added to the second model. Predictive models were constructed using multivariate logistic regression analysis. The best model was selected according to the area under the receiver operating characteristic curve. Results: The first model identified 4 independent factors: age, waist circumference, systolic blood pressure, and witnessed apnea episodes, with a sensitivity of 78%, specificity of 68%, and area under the receiver operating characteristic curve of .83 (95% confidence interval .76–.90, P < .001). The second model identified 2 independent factors (witness apnea episodes, oxygen desaturation index of ≥3%), with a sensitivity of 91%, specificity of 85%, and area under the receiver operating characteristic curve of .94 (95% confidence interval .89–.98, P < .001). The 2-step model predictive values were sensitivity of 90%, specificity of 91%, and accuracy of 90% (95% confidence interval 84–94%). After applying the first model and then the second, 45% of subjects would have been ruled out (15% and 30%, respectively) and 55% would require additional sleep management before BS. Conclusion: The proposed model could be useful for improving the management of complex patients before BS and optimizing limited polysomnography resources. [Copyright &y& Elsevier]

Abstract: Background: Home continuous positive airway pressure (CPAP) titration with automatic devices is not possible in a non-negligible percentage of patients with sleep apnea–hypopnea syndrome (SAHS). Objectives: To test the feasibility of a novel telemetric system for home CPAP titration. Methods: One-night home CPAP titration was carried out on 20 SAHS patients (56±3years; BMI=35±2kg/m2). A telemetric unit, based on the conventional GPRS mobile phone network and connected to a commercial CPAP device, allowed the hospital technician to monitor flow, pressure and air leaks by remote control and titrate CPAP (elimination of apneas, hypopneas, flow limitation and snoring) in real time. After 1 week, a full hospital polysomnography was performed while the patient was subjected to the value of CPAP that was previously titrated at home via telemetry. Results: The home-titrated CPAP systematically improved patients’ breathing: the apnea–hypopnea index and percentage of sleep time with arterial oxygen saturation below 90% were reduced from 58.1±5.1 to 3.8±0.6 events/h and from 19.8±1.1% to 4.4±0.7%, respectively. This CPAP value (9.15±0.47 cmH2O) was virtually the same as the pressure that optimized breathing during hospital polysomnography (9.20±0.41 cmH2O; mean difference: 0.02 cmH2O, limits of agreement:±1.00cmH2O). Conclusions: This pilot study shows that a simple telemetric system, requiring neither a special telemedicine network nor any infrastructure in the patient’s home, made it possible to perform effective remote CPAP titration on SAHS patients. [Copyright &y& Elsevier]

Summary: Nasal continuous positive airway pressure (CPAP) is an effective treatment for most patients with obstructive sleep apnea syndrome (OSAS), improving sleepiness, cognitive function and mood. A number of patients, however, complain about persistent sleepiness after CPAP. In these cases another clinical history should be carried out to confirm the diagnosis of OSAS, to check CPAP compliance and to exclude associated conditions such as poor sleep hygiene, depression, narcolepsy or idiopathic hypersomnia. If necessary, a full polysomnography (PSG) followed by a multiple sleep latency test or even a full PSG with CPAP titration should be performed. Experimental data in animals suggest that long-term intermittent hypoxia related to the apneic events could deteriorate the brain structures that regulate alertness. This impairment, if present in humans, could be another reason for residual sleepiness after CPAP. Modafinil has been shown to reduce subjective sleepiness after CPAP in OSAS patients. Further studies are warranted to clarify the way in which CPAP modifies sleepiness. [Copyright &y& Elsevier]

Abstract: Background: Rhinitis is a potential side effect of nasal continuous positive airway pressure (nCPAP). Heated Humidification (HH) is applied to treat rhinitic symptoms, but its usefulness is controversial. Confounding factors such as previous rhinitis or nasal obstruction make it difficult to draw definitive conclusions. Animal models could therefore be useful. Objectives: To study the effects of HH as a mechanism that may reduce nasal inflammation during nCPAP application in the presence or absence of an oral leak (OL). Methods: Prospective controlled animal study. Setting I: Sixty Sprague–Dawley rats were distributed into noCPAP (naïve), sham-CPAP with HH, 5 and 10cm H2O nCPAP, and 10cm H2O nCPAP with HH for 5h. Setting II: Thirty-three rats were exposed to nCPAP, nCPAP with a controlled OL, and nCPAP with controlled OL and HH (n =11 each). The degree of nasal inflammation was assessed by directly evaluating the percentage of neutrophils in the nasal mucosa. Results: Percentage of neutrophils was higher after 5h of 10cm nCPAP compared to the control group (0.96±0.26% vs. 0.18±0.05%; p =0.001). When HH was applied, the percentage of neutrophils did not differ from that observed in the nCPAP group. The addition of a controlled OL, did not show significant differences in the neutrophils count compared to nCPAP alone (0.75±0.19% vs. 0.83±0.29%; p =0.70). Moreover, the application of HH to the rat with OL did not change the percentage of neutrophils. Conclusions: HH applied to an acute rat model of nCPAP with and without a controlled OL does not seem to reduce nasal inflammation. [Copyright &y& Elsevier]

Power semiconductor devices are constructed to endure high voltages (>30 V) and manage high current density. Edge termination is a specific feature that must be integrated into the device architecture to achieve high voltage capability in vertical power components. It is necessary to design these edge terminations while taking into account the device's architecture and technology. Termination efficiency is the main factor, but its area is also of great significance. Many edge termination designs with efficiency close to 100 % have been reported and are currently used in commercial devices. However, having a near-100 % static breakdown voltage is not the only requirement in modern power devices. Today, most power applications rely on the avalanche capability as a key parameter. Avalanche capability is defined by the device ability to enter in non-destructive avalanche mode, where the component can temporarily sustain a high voltage and a high current in blocking mode. The Unclamped Inductive Switching (UIS) test can be used to measure the avalanche mode, and it can be customized to define a safe operating area for a full avalanche mode (SOA). The safe operation of both single pulse and repetitive pulsed avalanche limits can be characterized. Such operation mode is now controlled in both Silicon and Silicon Carbide based power devices. However, the development of novel wide and ultra-wide band gap semiconductors in regards to avalanche capability and SOA still require a lot of work. [ABSTRACT FROM AUTHOR]

This paper reviews advanced gate dielectric processes for SiC MOSFETs. The poor quality of the SiO 2 /SiC interface severely limits the value of the channel field-effect mobility, especially in 4H-SiC MOSFETs. Several strategies have been addressed to overcome this issue. Nitridation methods are effective in increasing the channel mobility and have been adopted by manufacturers for the first generations of commercial power devices. Gate oxide doping techniques have also been successfully implemented to further increase the channel mobility, although device stability is compromised. The use of high-k dielectrics is also analyzed, together with the impact of different crystal orientations on the channel mobility. Finally, the performance of SiC MOSFETs in harsh environments is also reviewed with special emphasis on high temperature operation. [ABSTRACT FROM AUTHOR]

Abstract In previous works, an alternative gate oxide configuration, based on a boron treatment, was proposed in order to enhance the SiO 2 /SiC interface quality, enabling high channel mobility n-channel 4H-SiC lateral MOSFETs. In this paper we study the effect of this treatment on 6H-SiC MOSFETs and we compare it to their 4H-SiC counterparts. The gate oxide boron treatment highly increases mobility values in 4H-SiC whereas the increase is lower in 6H-SiC. The mobility increase by the boron treatment in 4H-SiC MOSFETs is related to the decrease of near interface oxide traps (NIOTs). Then, a different NIOTs density and energy location can be seen as a possible explanation for the different mobility improvement behavior seen in both polytypes. [ABSTRACT FROM AUTHOR]

Abstract: Aims: Brugada syndrome is characterized by typical ECG features, ventricular arrhythmias and sudden cardiac death (SCD), more frequent during nighttime. Autonomic cardiovascular control has been implicated in triggering the ventricular arrhythmias. Sleep-disordered breathing (SDB) elicits marked autonomic changes during sleep and is also associated with an increased risk of nighttime SCD. Brugada patients may have a higher likelihood of SDB compared to controls. However, no data are available on cardiac autonomic control in Brugada patients, particularly with regard to the comorbidity of SDB. Methods: We evaluated autonomic cardiovascular control in Brugada patients with SDB (BRU-SDB, n=9), without SDB (BRU, n=9), in controls (CON, n=8) and in non-Brugada patients with SDB (n=6), during wakefulness and sleep (N2, N3 and REM). Linear spectral and entropy-derived measures of heart rate variability (HRV) were performed during apnea-free stable breathing epochs. Results: Total HRV was attenuated in BRU-SDB compared to CON and BRU. During N2 and REM, in BRU-SDB patients sympathetic modulation decreased compared to BRU and CON, while during REM, they showed an increased parasympathetic modulation, compared to the other two groups. BRU-SDB and SDB were similar in terms of spectral components. Entropy-derived indices showed preserved dynamic changes in Brugada patients compared to controls through the different sleep stages. Conclusion: Brugada syndrome per se does not appear associated with an altered autonomic cardiovascular control during wakefulness and sleep. The comorbidity with SDB may contribute to disrupted autonomic cardiovascular regulation during sleep, possibly predisposing to the increased likelihood of sleep-related ventricular tachyarrhythmias and SCD. [Copyright &y& Elsevier]

Abstract: Background: Obstructive sleep apnea (OSA) is associated with cardiovascular disorders, but the different comorbidities in OSA patients make it difficult to know their specific effects on the development of cardiovascular injury. The aim of the present study was to investigate whether recurrent obstructive apneas could lead to myocardial injury. Methods: Thirty-six male Sprague–Dawley rats (300–350g) were either acutely (3h) or sustainably (5h/day, for 10days) subjected to obstructive apneas with a pattern of 15s each, 60apneas/h. Corresponding control groups were formed for the acute and sustained models. To assess the induction of systemic inflammation, IL1-β was measured in plasma. Ventricular tissue injury was evaluated by histological techniques (presence of inflammatory cell infiltration, eosin autofluorescence, and detection of apoptosis). Results: After 3h of obstructive apneas, a significant increase in IL1-β (64.9±29.6ng/μl) were observed with respect to the controls (7.3±1.0ng/μl), but no myocardial injury was present. Conversely to the acute model, the systemic inflammation triggered by obstructive apneas for 10days was reduced. However, the percentage of area with enhanced eosin autofluorescence and of apoptotic cells (1.83±0.35% and 24.4±1.5%, respectively) was increased when compared to the control group (0.72±0.20% and 5.0±2.8%, respectively). Conclusions: This study suggests that obstructive apneas are a potential source of early systemic and ventricular inflammation and myocardial cell injury after sustained apneas application, which could represent an initial phase in the progression of heart disease associated with OSA. [Copyright &y& Elsevier]

We investigated breathing patterns and the occurrence of arrhythmias and ST-segment changes during sleep in patients with Brugada syndrome. Patients with Brugada syndrome are more likely to die from ventricular arrhythmias during sleep. ST-segment changes have been correlated with risk of sudden cardiac death. Whether sleep disturbances may contribute to arrhythmogenesis is unknown. Patients with Brugada syndrome underwent overnight polysomnography with simultaneous 12-lead electrocardiographic recording. A control group matched by age, gender, and body mass index (BMI) also underwent polysomnography. Twenty patients were included (50 ± 15 years old, 75% men). Despite their normal BMI (24.7 ± 2.7 kg/m2), 45% had sleep-disordered breathing (SDB), with a mean apnea-hypopnea index of 17.2 ± 14 events/hour. In patients with a high risk of arrhythmias, 5 (63%) had SDB. In the control group, 27% had SDB. Atrial or ventricular arrhythmias were not observed. Spontaneous ST-segment changes occurred in 2 patients over 45 different time points. Most ST-segment changes were observed during rapid eye movement sleep (31%) or within 1 minute of arousals (44%). Regarding respiratory events, 25 (56%) of ST-segment changes were related to occurrence of apnea or hypopnea. In conclusion, patients with Brugada syndrome have a high prevalence of SDB even in the setting of normal BMI. The higher incidence of nocturnal death in patients with Brugada syndrome may be conceivably related to co-morbid SDB. Moreover, autonomic instability encountered in rapid eye movement sleep and arousals could potentiate the risk of arrhythmias. [Copyright &y& Elsevier]