Proton magnetic resonance spectroscopy of brain in obstructive sleep apnea in Egyptian subjects

AbstractObjectiveThe overall objective of this work is to study the cerebral metabolic changes in patients with OSA and to determine the usefulness of MRS as an objective method for evaluation of CNS impairment in these patients.Materials and methodsThis study included two groups; group1 fifteen (15) patients diagnosed with obstructive sleep apnea hypopnea syndrome, and group 2 ten (10) healthy volunteers of comparable age.Magnetic resonance spectra were obtained from frontal periventricular white matter.For all subjects, height, body weight, and BMI were assessed. Waist and hip circumference were measured and waist/hip ratio (W/H ratio) was calculated.Overnight polysomnography (PSG) to identify sleep apnea was done. Daytime sleepiness was evaluated by the Epworth Sleepiness Scale. Symptoms of anxiety and depression were measured with the Hospital Anxiety and Depression Scale (HADS).ResultsN-acetylaspartate-to-creatine (NAA/Cr) and choline-to-creatine (Cho/Cr) ratios were significantly lower in the frontal white matter of obstructive sleep apnea patients when compared to controls. Absolute concentrations of N-acetylaspartate (NAA) and choline (Cho) were also significantly reduced in the frontal white matter of patients with sleep apnea. Statistically significant negative correlations existed between AHI and metabolites concentrations and ratios in patients with OSAHS. Significant positive correlations existed in patients with OSAHS between Hospital and depression scale for depression (HAD-D) and AHI (r=0.764, p=0.001), ODI (r=0.571, p=0.026), and ESS (r=0.644, p=0.010), respectively. Significant positive correlations existed in patients with OSAHS between Hospital and depression scale for anxiety (HAD-A) and AHI (r=0.753, p=0.001), and ESS (r=0.537, p=0.039), respectively. Multivariate Linear regression model of factors predictive showed AHI as the main predictor factor for choline to creatine ratio in patients with OSAHS with t=5.180, at p<0.001.ConclusionOSA patients show abnormal brain metabolites related to neuronal damage due to intermittent chronic hypoxemia. Anxious and depressive symptoms are highly prevalent in patients with severe untreated OSAS. The severity of depressive and anxious symptoms may be related to excessive daytime sleepiness and to nocturnal hypoxemia both of which are strongly correlated to brain metabolites. AHI seems to be the main predictor factor for choline to creatine ratio in patients with OSAHS

Broadcasting in MANETs using multi-source Random Linear Network Coding

Multicasting and broadcasting are important communication techniques in wireless adhoc networks. Recently, Network Coding (NC), which has emerged as a promising technique for various applications, has been applied to multicast and broadcast in wireless adhoc networks. Random Linear Network Coding (RLNC) is one type of NC that does not require prior knowledge of what the neighbours have received and therefore is relatively easy to implement as a distributed protocol, even in highly mobile adhoc environments

Adaptive Random Linear Network Coding with controlled forwarding for wireless broadcast

Multicasting and Broadcasting are important communication techniques in wireless adhoc networks to disseminate control messages and other important information during emergencies, battlefield operations, disaster relief efforts, etc. In this paper we propose an adaptive multi-source broadcasting protocol using Random Linear Network Coding. One key feature of this protocol is its multi-source operation, coding packets from different sources in the same generation. The protocol also efficiently controls the number of re-transmissions based on neighborhood information, limits the size of generations by introducing the concept of Generation Distance (GD) for multi-source operation, supports early decoding, and adaptively calculates the time-out for generations based on the generation size and transmission rate (packets/sec). Simulation results show that inter-mixing of packets from different sources results in improved Packet Delivery Ratio (PDR) as well as lower latency, compared to the already proposed single-source schemes. We also investigated its adaptive performance compared to a baseline flooding protocol and show that our protocol delivers consistently high PDR and low latency in both single-source and multi-source scenarios for a range of network densities and traffic rates

Mitigating Network Denial-of-Service through Diversity-Based Traffic Management

In this paper we explore the feasibility of mitigating network denial-of-service (NDoS) attacks (attacks that consume network bandwidth) by dynamically regulating learned classes of network traffic. Ou