Lack of Effect of Sleep Apnea on Oxidative Stress in Obstructive Sleep Apnea Syndrome (OSAS) Patients

PURPOSE: The aim of this study was to evaluate markers of systemic oxidative stress and antioxidant capacity in subjects with and without OSAS in order to investigate the most important factors that determine the oxidant-antioxidant status. METHODS: A total of 66 subjects referred to our Sleep laboratory were examined by full polysomnography. Oxidative stress and antioxidant activity were assessed by measurement of the derivatives of reactive oxygen metabolites (d-ROMs) and the biological antioxidant capacity (BAP) in blood samples taken in the morning after the sleep study. Known risk factors for oxidative stress, such as age, sex, obesity, smoking, hypelipidemia, and hypertension, were investigated as possible confounding factors. RESULTS: 42 patients with OSAS (Apnea-Hypopnea index >15 events/hour) were compared with 24 controls (AHI<5). The levels of d-ROMS were significantly higher (p = 0.005) in the control group but the levels of antioxidant capacity were significantly lower (p = 0.004) in OSAS patients. The most important factors predicting the variance of oxidative stress were obesity, smoking habit, and sex. Parameters of sleep apnea severity were not associated with oxidative stress. Minimal oxygen desaturation and smoking habit were the most important predicting factors of BAP levels. CONCLUSION: Obesity, smoking, and sex are the most important determinants of oxidative stress in OSAS subjects. Sleep apnea might enhance oxidative stress by the reduction of antioxidant capacity of blood due to nocturnal hypoxia

Parallel ray tracing with 5D adaptive subdivison

We present strategies for parallelising ray tracing based on 5D adaptive subdivision. Our goals are to obtain good speed-up and to efficiently balance the load between the processors while minimising the required memory per processor inherently large in 5D subdivision. First, loosely coupled strategies are presented, which are ideal for implementation on clusters of workstations, the most commonly used form of parallel processing nowadays. Then we consider a tightly coupled algorithm ideal for multiprocessors with fast interconnection network or shared memory. Finally, results on a cluster of workstations are presented and discussed

Parallel Ray Tracing with 5D Adaptive Subdivision

We present strategies for parallelising ray tracing based on 5D adaptive subdivision. Our goals are to obtain good speed-up and to efficiently balance the load between the processors while minimising the required memory per processor inherently large in 5D subdivision. First, loosely coupled strategies are presented, which are ideal for implementation on clusters of workstations, the most commonly used form of parallel processing nowadays. Then we consider a tightly coupled algorithm ideal for multiprocessors with fast interconnection network or shared memory. Finally, results on a cluster of workstations are presented and discussed

Lack of effect of sleep apnea on oxidative stress in obstructive sleep apnea syndrome (OSAS) patients

Purpose: The aim of this study was to evaluate markers of systemic oxidative stress and antioxidant capacity in subjects with and without OSAS in order to investigate the most important factors that determine the oxidant-antioxidant status. Methods: A total of 66 subjects referred to our Sleep laboratory were examined by full polysomnography. Oxidative stress and antioxidant activity were assessed by measurement of the derivatives of reactive oxygen metabolites (d-ROMs) and the biological antioxidant capacity (BAP) in blood samples taken in the morning after the sleep study. Known risk factors for oxidative stress, such as age, sex, obesity, smoking, hypelipidemia, and hypertension, were investigated as possible confounding factors. Results: 42 patients with OSAS (Apnea-Hypopnea index &amp;15 events/hour) were compared with 24 controls (AHI&lt;5). The levels of d-ROMS were significantly higher (p = 0.005) in the control group but the levels of antioxidant capacity were significantly lower (p = 0.004) in OSAS patients. The most important factors predicting the variance of oxidative stress were obesity, smoking habit, and sex. Parameters of sleep apnea severity were not associated with oxidative stress. Minimal oxygen desaturation and smoking habit were the most important predicting factors of BAP levels. Conclusion: Obesity, smoking, and sex are the most important determinants of oxidative stress in OSAS subjects. Sleep apnea might enhance oxidative stress by the reduction of antioxidant capacity of blood due to nocturnal hypoxia. © 2012 Simiakakis et al

Comparison between OSAS patients and control subjects.

<p>Comparison between OSAS patients and control subjects.</p

Correlations of d-ROMs metabolites.

<p>Correlations of d-ROMs metabolites.</p