No evidence of enhanced oxidant production in blood obtained from patients with obstructive sleep apnea

The relation of dietary components with severity of obstructive sleep apnea in Cypriot patients: A randomized, stratified epidemiological study

Background

Obstructive Sleep Apnea (OSA) is considered a public health problem and its prevalence is increasing at an epidemic rate. The aim of this study was to examine whether individual nutrients (macronutrients, antioxidant vitamins) rather than energy restriction may potentially affect OSA severity in a representative population of Cyprus.

Methods

A total sample of 303 adults (>18 years old) with Cypriot citizenship and permanently residing in Cyprus were randomly selected. Selected patients have completed the food frequency questionnaire, and a physical activity questionnaire and underwent a sleep study to assess OSA severity.

Results

Overall, 303 patients were included in this study, 169 (55.8%) had mild OSA (apnea-hypopnea index—AHI <15) and the remaining 83 (27.4%) had moderate to severe OSA (AHI>15). The mean age of all patients was 55.7 years old. Patients with moderate to severe OSA had significant higher BMI levels, higher consumption of calories, higher hip circumference, waist circumference, waist-hip ratio and neck circumference and higher consumption of folic acid compared with the patients with mild OSA (p<0.05).

Conclusions

The findings suggest that increased energy intake regardless diet macronutrient composition is positively associated with OSA severity whereas higher folic acid intake seems to have a protective role.

The role of antioxidant vitamins and selenium in patients with obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is a disorder characterized by recurrent episodes of obstruction of the upper respiratory tract during sleep often accompanied by oxygen desaturations. Antioxidant defense mechanisms are important to prevent OSA-associated diseases and decrease mortality. We aimed to determine the levels of selenium and vitamins A, C, and E in patients with OSA but without any comorbidities and compare the results with a control group, theorizing that the findings may be helpful to understand the antioxidant mechanisms in the pathogenesis of OSA and associated diseases.

METHODS

We designed a case-control study with 146 subjects. Subjects were categorized into four groups by apnea-hypopnea index (AHI) scores: control (n = 32; AHI < 5), mild OSA (n = 32; 5 ≤ AHI < 15), moderate OSA (n = 34; 15 ≤ AHI < 30), and severe OSA (n = 48; AHI ≥ 30) groups. Serum levels of selenium were measured by atomic absorption spectrometer. Vitamin A, C, and E levels were measured by high-performance liquid chromatography and ultraviolet (HPLC-UV) detector.

RESULTS

After adjusting for age, BMI, and gender, serum selenium and vitamin A levels were found to be higher in patients with OSA compared with controls (ANCOVA, p < 0.008, and p = 0.014 respectively), and levels of these markers increased with the severity of the disease. AHI was positively correlated with selenium (r = 0.289; p < 0.001), and vitamin A levels (r = 0.276; p < 0.001).

CONCLUSION

These results demonstrated that antioxidant response with increased vitamin A, and selenium concentrations, may be important defense mechanisms in patients with OSA patients who do not have other comorbidities. Antioxidant nutrients or supplements may be implemented as a complementary treatment of OSA to support antioxidant defense.

Monitoring of microwave emission of HRP system during the enzyme functioning

Monitoring of microwave emission from aqueous solution of horseradish peroxidase (HRP) in the process of the enzyme functioning was carried out. For the monitoring, a system containing HRP, luminol and Н₂О₂ was employed. Microwave emission measurements were carried out in the 3.4-4.2 GHz frequency range using the active and passive modes (active-mode and passive-mode measurements). In the active mode, excitation of the solution in the pulsed electromagnetic field was accomplished. In the passive mode, no excitation was induced. It appears that the passive-mode measurements taken in the course of the peroxidase reaction in the enzyme system have shown a 0.5 °С increase of the microwave signal. Upon the active-mode measurements, taken in the same reaction conditions, the forced excitation of the solution has also led to the increase (by 2 °С) of the level of the microwave signal - i.e. to its 4-fold enhancement compared to the signal obtained in passive-mode measurements.

Renal vasodilating capacity and endothelial function are impaired in patients with obstructive sleep apnea syndrome and no traditional cardiovascular risk factors

OBJECTIVE

Patients with obstructive sleep apnea syndrome exhibit accelerated vascular aging and renal damage. Aim of the study was to investigate whether vascular dysfunction is a feature of obstructive sleep apnea syndrome per se or instead related to the presence of traditional cardiovascular risk factors.

METHODS

Forty patients with moderate-severe obstructive sleep apnea syndrome (20 with, 20 without traditional risk factors) and 20 matched healthy controls were enrolled. Renal vasodilating capacity, endothelium-dependent vasodilation in the brachial artery, carotid-femoral pulse wave velocity and carotid stiffness were measured. Oxidative stress, endothelial biomarkers and leukocyte adhesion molecule levels were also evaluated.

RESULTS

Apneic patients without traditional cardiovascular risk factors presented reduced endothelium-dependent vasodilation (3.7±2.1 versus 6.1±3.0%, P<0.05), increased serum E-selectin (49.8±11.5 versus 38.9±17.9 ng/ml, P<0.05), and impaired renal vasodilating capacity (6.0±4.3 versus 10.4±6.1%, P<0.05), as compared to healthy controls. Endothelial NO synthase expression was reduced (0.0133 versus 0.0221×10 copies/μg RNA, P<0.05), whereas oxidative stress parameters and leukocyte adhesion molecules were similar to controls. Patients with obstructive sleep apnea syndrome and traditional risk factors also exhibit increased aortic and carotid stiffness, increased renal resistive index and intima-media thickness, and reduced expression of the endothelial progenitor cell marker CD34: however, these parameters were similar to those of healthy controls in patients with isolated obstructive sleep apnea syndrome.

CONCLUSION

Obstructive sleep apnea syndrome is characterized by endothelial dysfunction and activation and impaired renal vasodilating capacity even in the absence of traditional cardiovascular risk factors, possibly due to reduced endothelial NO synthase expression.

Oxidative stress in patients with obstructive sleep apnea syndrome

PURPOSE

We aimed to investigate whether systemic oxidative stress is increased in patients with obstructive sleep apnea syndrome (OSAS).

METHODS

A total of 18 patients with severe OSAS and 13 controls were included in the study. Inclusion criteria for OSAS patients were: snoring and apnea-hypopnea index (AHI) of >30 in full polysomnography, no previous treatment for OSAS, non-smoking status, and a medical history of being free of comorbidities known to increase oxidative stress. Controls were recruited among subjects assessed for snoring in the Sleep Laboratory Department if they had AHI<5. At baseline, patients were evaluated by the Epworth Sleepiness Scale and underwent spirometry, echocardiography, and full polysomnographic study. Blood samples were collected for evaluation of oxidative stress biomarkers [protein carbonyls, reduced (GSH) and oxidized (GSSG) glutathione, 8-isoprostane, thiobarbituric acid-reactive substances (TBARS), catalase activity, Cu-Zn superoxide dysmutase (SOD), total antioxidant capacity (TAC)] before and on the morning following polysomnography.

RESULTS

The overnight (morning-night) change (%) of GSH/GSSG ratio and GSH was significantly different between OSAS and controls (p = 0.03 and p = 0.048, respectively). Plasma protein carbonyls, erythrocyte catalase activity, 8-isoprostane, SOD, TBARS, and TAC plasma values were not different between OSAS and controls (p > 0.05). No significant correlation was found between changes in the levels of biomarkers and AHI, arousal, or desaturation index.

CONCLUSION

The present prospective investigation in a population free of comorbidities or factors which may increase systemic oxidative stress provides evidence that obstructive sleep apnea per se might be associated with increased oxidative burden possibly via GSH/GSSG pathway.

Sleep-disordered breathing and pregnancy: potential mechanisms and evidence for maternal and fetal morbidity

PURPOSE OF REVIEW

This article reviews current data on pathophysiologic mechanisms by which sleep-disordered breathing during pregnancy may cause harm, and explores biological pathways for associated adverse maternal and fetal outcomes, especially pregnancy-induced hypertension and gestational diabetes.

RECENT FINDINGS

Accumulating data indicate that snoring and sleep apnea during pregnancy are likely to increase the risk for gestational hypertension and preeclampsia. Several new studies have observed that sleep-disordered breathing and short sleep duration also increase the risk of gestational diabetes, similar to observations in the general population. There are varying levels of emerging evidence for potential mechanisms, including oxidative stress, increased sympathetic activity and inflammation, adipokine levels and insulin resistance, linking sleep-disordered breathing events during pregnancy to adverse outcomes.

SUMMARY

Sleep-disordered breathing and adverse maternal-fetal outcomes such as preeclampsia and gestational diabetes share a number of mechanistic pathways, and growing data in pregnant women indicate that snoring and sleep apnea increase the risk of these and other complications for both the mother and the fetus. Nevertheless, direct evidence of the pathophysiologic mechanisms by which sleep-disordered breathing during pregnancy exerts negative effects remains sparse.