Oxidative stress in patients with obstructive sleep apnea syndrome

Unraveling the Complexities of Oxidative Stress and Inflammation Biomarkers in Obstructive Sleep Apnea Syndrome: A Comprehensive Review

BACKGROUND

Obstructive sleep apnea syndrome (OSAS), affecting approximately 1 billion adults globally, is characterized by recurrent airway obstruction during sleep, leading to oxygen desaturation, elevated carbon dioxide levels, and disrupted sleep architecture. OSAS significantly impacts quality of life and is associated with increased morbidity and mortality, particularly in the cardiovascular and cognitive domains. The cyclic pattern of intermittent hypoxia in OSAS triggers oxidative stress, contributing to cellular damage. This review explores the intricate relationship between OSAS and oxidative stress, shedding light on molecular mechanisms and potential therapeutic interventions.

METHODS

A comprehensive review spanning from 2000 to 2023 was conducted using the PubMed, Cochrane, and EMBASE databases. Inclusion criteria encompassed English articles focusing on adults or animals and reporting values for oxidative stress and inflammation biomarkers.

RESULTS

The review delineates the imbalance between pro-inflammatory and anti-inflammatory factors in OSAS, leading to heightened oxidative stress. Reactive oxygen species biomarkers, nitric oxide, inflammatory cytokines, endothelial dysfunction, and antioxidant defense mechanisms are explored in the context of OSAS. OSAS-related complications include cardiovascular disorders, neurological impairments, metabolic dysfunction, and a potential link to cancer. This review emphasizes the potential of antioxidant therapy as a complementary treatment strategy.

CONCLUSIONS

Understanding the molecular intricacies of oxidative stress in OSAS is crucial for developing targeted therapeutic interventions. The comprehensive analysis of biomarkers provides insights into the complex interplay between OSAS and systemic complications, offering avenues for future research and therapeutic advancements in this multifaceted sleep disorder.

Oxidative Stress in Obstructive Sleep Apnea Syndrome: Putative Pathways to Hearing System Impairment

INTRODUCTION

OSAS is a disease that affects 2% of men and 4% of women of middle age. It is a major health public problem because untreated OSAS could lead to cardiovascular, metabolic, and cerebrovascular complications. The more accepted theory relates to oxidative stress due to intermittent hypoxia, which leads, after an intense inflammatory response through multiple pathways, to endothelial damage. The objective of this study is to demonstrate a correlation between OSAS and hearing loss, the effect of the CPAP on hearing function, and if oxidative stress is also involved in the damaging of the hearing system.

METHODS

A review of the literature has been executed. Eight articles have been found, where seven were about the correlation between OSAS and the hearing system, and only one was about the CPAP effects. It is noted that two of the eight articles explored the theory of oxidative stress due to intermittent hypoxia.

RESULTS

All studies showed a significant correlation between OSAS and hearing function (p < 0.05).

CONCLUSIONS

Untreated OSAS affects the hearing system at multiple levels. Oxidative stress due to intermittent hypoxia is the main pathogenetic mechanism of damage. CPAP has no effects (positive or negative) on hearing function. More studies are needed, with the evaluation of extended high frequencies, the execution of vocal audiometry in noisy environments, and the evaluation of potential biomarkers due to oxidative stress.

Investigating the Relationship between Obstructive Sleep Apnoea, Inflammation and Cardio-Metabolic Diseases

Obstructive sleep apnoea (OSA) is a prevalent underdiagnosed disorder whose incidence increases with age and weight. Uniquely characterised by frequent breathing interruptions during sleep-known as intermittent hypoxia (IH)-OSA disrupts the circadian rhythm. Patients with OSA have repeated episodes of hypoxia and reoxygenation, leading to systemic consequences. OSA consequences range from apparent symptoms like excessive daytime sleepiness, neurocognitive deterioration and decreased quality of life to pathological complications characterised by elevated biomarkers linked to endocrine-metabolic and cardiovascular changes. OSA is a well-recognized risk factor for cardiovascular and cerebrovascular diseases. Furthermore, OSA is linked to other conditions that worsen cardiovascular outcomes, such as obesity. The relationship between OSA and obesity is complex and reciprocal, involving interaction between biological and lifestyle factors. The pathogenesis of both OSA and obesity involve oxidative stress, inflammation and metabolic dysregulation. The current medical practice uses continuous positive airway pressure (CPAP) as the gold standard tool to manage OSA. It has been shown to improve symptoms and cardiac function, reduce cardiovascular risk and normalise biomarkers. Nonetheless, a full understanding of the factors involved in the deleterious effects of OSA and the best methods to eliminate their occurrence are still poorly understood. In this review, we present the factors and evidence linking OSA to increased risk of cardiovascular conditions.

Saliva Analysis of pH and Antioxidant Capacity in Adult Obstructive Sleep Apnea Patients

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) may be associated with and activates the stress response system, and variation in the physiological antioxidant capacity of body fluids. Our aim was to evaluate the variation of pH and antioxidant capacity on the saliva of obstructive sleep apnea subjects (OG) compared to a control group (CG).

METHOD

Fifty subjects with moderate/severe OSAS were recruited in Tor Vergata Hospital and compared with 20 healthy subjects CG. The buffer and the antioxidant capacity of the samples were quantified measuring the pH and the percentage of total salivary antioxidant capacity (%TAC), which refers to the reduced glutathione salivary concentration (GSH). Moreover, the protein concentration and the gelatinolytic activity of metalloproteinases were quantified.

RESULTS

The data showed that the pH value is slightly more alkaline in OSAS subjects; however, it is not directly related to the severity of OSAS. The %TAC was found to be significantly reduced by 86.2% in the OG. Proteins of saliva from the OG were found 1.5 times more concentrated than in the healthy sample. The gelatinolytic activity of metalloproteinases of healthy and OSA did not show statistically significant changes.

CONCLUSIONS

The salivary samples from OSAS compared to CG show an alteration of the oxidative state, the pH buffering power, and protein concentrations, inducing conditions that can easily evolve chronic gingivitis. Further investigations are necessary to evaluate the feasibility of using salivary fluid for the early diagnosis of oral or systemic problems in OSAS subjects.

Obstructive Sleep Apnea Syndrome: The Effect of Acute and Chronic Responses of Exercise

Obstructive Sleep Apnea Syndrome (OSAS) is a sleep disorder with high prevalence in general population, but alarmingly low in clinicians' differential diagnosis. We reviewed the literature on PubMed and Scopus from June 1980–2021 in order to describe the altered systematic pathophysiologic mechanisms in OSAS patients as well as to propose an exercise program for these patients. Exercise prevents a dysregulation of both daytime and nighttime cardiovascular autonomic function, reduces body weight, halts the onset and progress of insulin resistance, while it ameliorates excessive daytime sleepiness, cognitive decline, and mood disturbances, contributing to an overall greater sleep quality and quality of life.

Circulating Superoxide Dismutase Concentrations in Obstructive Sleep Apnoea (OSA): A Systematic Review and Meta-Analysis

Obstructive Sleep Apnoea (OSA) is characterized by a pro-oxidant state that results from the recurrent hypoxia-reoxygenation cycles. Superoxide dismutase (SOD), a key antioxidant enzyme involved in the detoxification of superoxide radicals, could represent a reliable marker to monitor the antioxidant defences in OSA. In order to capture and critically appraise the available evidence, we performed a systematic review and meta-analysis of studies reporting SOD concentrations in OSA patients and non-OSA controls in the electronic databases Pubmed, Web of Science, Scopus and Google Scholar. In total, 13 studies in 847 OSA patients and 438 non-OSA controls were included in the meta-analysis. Blood SOD concentrations were significantly lower in OSA patients (SMD = 0.87, p < 0.001). By contrast, serum/plasma SOD concentrations were not significantly different between the two groups. Although extreme between-study heterogeneity was observed, the SMD was not substantially modified when individual studies were sequentially removed. In conclusion, we observed that whole blood, but not serum/plasma, SOD concentrations were significantly lower in OSA patients compared with controls. Our meta-analysis suggests an impaired antioxidant defence in OSA that is more robustly assessed in the corpuscular biological matrix and provides useful background information for further studies investigating the association between SOD changes and clinical status in OSA.

Association between the circulating superoxide dismutase and obstructive sleep apnea: a meta-analysis

PURPOSE

Although it has been reported that superoxide dismutase (SOD) is related to obstructive sleep apnea (OSA), the results are controversial. In addition, the effects of the continuous positive airway pressure (CPAP) treatment on SOD levels are also inconsistent. The primary purpose of the present meta-analysis is to determine the relationship between the circulating SOD levels and OSA.

METHODS

The studies included in this meta-analysis were selected from the PubMed, Embase, Cochrane Library, and Scopus databases. Two researchers independently reviewed the studies. Data analysis was performed using Stata 15.1. The overall effects were measured using the standardized mean difference (SMD) with a 95% confidence interval (CI). A random-effects model or a fixed-effects model was used, depending on the heterogeneity of the studies.

RESULTS

A total of 14 studies were included, comprising 1240 patients and 457 controls. The results showed that the circulating SOD levels of the patients with OSA were significantly lower than that of the control group (SMD = - 1.645, 95% CI = - 2.279 to - 1.011, P < 0.001). We also studied changes in the circulating SOD levels in patients with OSA after the CPAP treatment. No significant difference was observed in the circulating SOD levels after the CPAP treatment (SMD = - 0.028, 95% CI = - 0.218 to 0.162, P = 0.772).

CONCLUSION

The results suggested that patients with OSA have reduced levels of SOD and were related to disease severity. The results also indicated that circulating SOD levels may be a reliable marker for detecting systemic oxidative stress in patients with OSA. However, the circulating SOD levels were not affected by the short-term (4-12 weeks) CPAP treatment. Therefore, further large-scale, well-designed randomized controlled trials with a longer CPAP therapy (more than 6 months preferably) and good adherence to the treatment are needed to investigate this issue.

Circulating Malondialdehyde Concentrations in Obstructive Sleep Apnea (OSA): A Systematic Review and Meta-Analysis with Meta-Regression

Oxidative stress induced by nocturnal intermittent hypoxia plays a significant pathophysiological role in obstructive sleep apnea (OSA). Malondialdehyde (MDA), one of the most commonly investigated markers of lipid peroxidation, might assist with the monitoring of oxidative balance in OSA. We conducted a systematic review and meta-analysis to evaluate the differences in circulating MDA concentrations between patients with OSA and non-OSA controls. A systematic search was conducted in the electronic databases Pubmed, Web of Science, Scopus and Google Scholar from inception to December 2020 by using the following terms: “malondialdehyde” or “MDA”; and “Obstructive Sleep Apnea Syndrome”, “OSAS” or “OSA”. We identified 26 studies in 1223 OSA patients and 716 controls. The pooled MDA concentrations were significantly higher in patients with OSA (standardized mean difference (SMD) 1.43 μmol/L, 95% confidence interval (CI) 1.03 to 1.83 μmol/L, p < 0.001). There was extreme heterogeneity between the studies (I² = 92.3%, p < 0.001). In meta-regression analysis, the SMD was significantly associated with age, the assay type used and publication year. In our meta-analysis, MDA concentrations were significantly higher in OSA patients than in controls. This finding suggests that MDA, which is a marker of lipid peroxidation, is involved in the pathogenesis of OSA and provides insights for future studies investigating its potential clinical use.

The effect of obstructive sleep apnea on peripheral blood amino acid and biogenic amine metabolome at multiple time points overnight

There are no clinical studies that have investigated the differences in blood serum metabolome between obstructive sleep apnea (OSA) patients and controls. In a single-center prospective observational study, we compared metabolomic profiles in the serum of OSA patients with apnea–hypopnea index (AHI) ≥ 15/h and control individuals. Peripheral blood was obtained at 3 different time points overnight: 9:00 p.m.; 5:00 a.m. and 7:00 a.m. We used a targeted approach for detecting amino acids and biogenic amines and analyzed the data with ranked general linear model for repeated measures. We recruited 31 patients with moderate-to-severe OSA and 32 controls. Significant elevations in median concentrations of alanine, proline and kynurenine in OSA patients compared to controls were detected. Significant changes in the overnight dynamics of serum concentrations occurred in OSA: glutamine, serine, threonine, tryptophan, kynurenine and glycine levels increased, whereas a fall occurred in the same biomarker levels in controls. Phenylalanine and proline levels decreased slightly, compared to a steeper fall in controls. The study indicates that serum profiles of amino acid and biogenic amines are significantly altered in patients with OSA referring to vast pathophysiologic shifts reflected in the systemic metabolism.

Premature ejaculation in OSAS: Does it improve with CPAP treatment?

AIM

Premature ejaculation (PE) is a common problem in male sexual health that significantly affects the quality of life. We aimed to evaluate the association of PE with obstructive sleep apnoea syndrome (OSAS), which is characterised by chronic oxidative stress, and to assess the effects of continuous positive airway pressure (CPAP) therapy on PE.

MATERIAL AND METHODS

Sexually active men between the ages of 20 and 50 who were newly diagnosed with PE, and diagnosed with moderate or severe OSAS were included in the study. Arabic Premature Ejaculation Index (AIPE) and Intravaginal Ejection Delay Time (IELT) were questioned for the diagnosis of PE. Patients with OSAS who accepted to participate in the study were given 1 year of CPAP treatment, and AIPE and IELT were questioned again, after the treatment. The results are compared with the results of the control group.

RESULTS

In total, 80 control subjects without OSAS, 85 patients with moderate OSAS and 82 patients with severe OSAS were included in the study. There were no significant differences between the groups in terms of age, BMI or thyroid function test results. Initial IELT and AIPE scores were significantly higher in the control group compared with the OSAS groups (for the IELT, 155.63 ± 98.78 vs 96.23 ± 60.60 and 62.86 ± 40.49; for the AIPE 26.18 ± 3.88 vs 18.71 ± 3.43 and 17.85 ± 3.83). Compared with initial (pretreatment) values, both scores improved significantly in both OSAS groups after 1 year of CPAP therapy (in moderate OSAS group, 96.23 ± 60.60 vs 134.17 ± 83.43 and 18.71 ± 3.43 vs 23.25 ± 3.43 and severe OSAS group 62.86 ± 40.49 vs 112.25 ± 71.58 and 17.85 ± 3.83 vs 24.18 ± 3.53).

CONCLUSION

For the first time in literature, we determined that the presence of OSAS was associated with significantly worse IELT and AIPE scores in males with PE, and the treatment of OSAS was related to the significant improvements in both scores, in the absence of any specific treatments for PE.

Increased the circulating levels of malondialdehyde in patients with obstructive sleep apnea: a systematic review and meta-analysis

PURPOSE

Obstructive sleep apnea (OSA) is a prevalent sleep disorder associated with increased risk of cardiovascular disease. Several studies have demonstrated elevated oxidative stress in patients with OSA. This oxidative stress is a direct inducer of lipid peroxidation. Malondialdehyde (MDA), a robust marker of lipid peroxidation, has been evaluated in patients with OSA but results have been inconsistent. The present systematic review and meta-analysis was performed to quantify the circulating levels of MDA in patients with OSA compared to controls.

METHODS

Search was performed in data bases of PubMed, Scopus, EMBASE, Web of Science, and Cochrane library, to find out those studies that measured MDA in patients with OSA compared to controls.

RESULTS

The search produced 563 records and after removing duplicates, 383 records remained. Screening by title and abstract and the evaluation of the full text resulted in the selection of 14 articles, which were included in the meta-analysis. Pooled analysis demonstrated higher levels of MDA in the patients compared to the controls (SMD (95% CI): 1.18 (0.68, 1.68), p < 0.0001).

CONCLUSION

The results of this meta-analysis demonstrated considerable elevation of MDA in patients with OSA compared to controls. The meta-analysis also indicated a positive association of MDA levels with the degree of severity of OSA. These results suggest a state of increased lipid peroxidation in patients with OSA.

Oxidative Stress and Inflammation Biomarker Expression in Obstructive Sleep Apnea Patients

Obstructive Sleep Apnea Syndrome (OSAS) is a respiratory sleep disorder characterised by repeated episodes of partial or complete obstruction of the upper airway during the night. This obstruction usually occurs with a reduction (hypopnea) or complete cessation (apnea) of the airflow in the upper airways with the persistence of thoracic-diaphragmatic respiratory movements. During the hypopnea/apnea events, poor alveolar ventilation reduces the oxygen saturation in the arterial blood (SaO₂) and a gradual increase in the partial arterial pressure of carbon dioxide (PaCO₂). The direct consequence of the intermittent hypoxia is an oxidative imbalance, with reactive oxygen species production and the inflammatory cascade’s activation with pro and anti-inflammatory cytokines growth. Tumour necrosis factors, inflammatory cytokines (IL2, IL4, IL6), lipid peroxidation, and cell-free DNA have been found to increase in OSAS patients. However, even though different risk-related markers have been described and analysed in the literature, it has not yet been clarified whether specified inflammatory bio-markers better correlates with OSAS diagnosis and its clinical evolution/comorbidities. We perform a scientific literature review to discuss inflammatory and oxidative stress biomarkers currently tested in OSAS patients and their correlation with the disease’s severity and treatment.

The Role of Vitamin C in Two Distinct Physiological States: Physical Activity and Sleep

This paper is a literature overview of the complex relationship between vitamin C and two opposing physiological states, physical activity and sleep. The evidence suggests a clinically important bidirectional association between these two phenomena mediated by different physiological mechanisms. With this in mind, and knowing that both states share a connection with oxidative stress, we discuss the existing body of evidence to answer the question of whether vitamin C supplementation can be beneficial in the context of sleep health and key aspects of physical activity, such as performance, metabolic changes, and antioxidant function. We analyze the effect of ascorbic acid on the main sleep components, sleep duration and quality, focusing on the most common disorders: insomnia, obstructive sleep apnea, and restless legs syndrome. Deeper understanding of those interactions has implications for both public health and clinical practice.

New Indices from Polysomnographic Measures for the Severity of Obstructive Sleep Apnea Syndrome -A Different Look at Obstructive Sleep Apnea Syndrome

Introduction

Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent abnormal respiratory events during sleep and causes oxidative stress which is reported as a major pathogenic mechanism for the development of various cardiovascular disorders. For the diagnosis and management of treatment, disease-related symptoms and the Apnea-Hypopnea Index (AHI) measured from polysomnographic (PSG) recordings are taken together. However, AHI do not sufficiently represent the total hypoxic load, and other indices related to apnea frequency, apnea duration, and desaturation degree should be investigated.

Methods

In this study, 317 polysomnographic recordings were retrospectively evaluated. Apart from the conventional AHI, apnea and/or hypopnea duration percentage (AHDP) and desaturation area (DesatArea) were calculated using PSG data.

Results

According to the AHI, 21.8%, 32.8% and 45.4% of cases were grouped as mild, moderate and severe OSAS, respectively. When AHDP was taken into account, 10.4%, 22.1% and 67.5% of the cases were regrouped as mild, moderate or severe OSAS, respectively. When the DesatArea calculation was used, the grouping of cases as mild, moderate or severe OSAS changed in value to 10.7%, 21.1% and 68.1%, respectively. The total group change was found to be 58.4% for both the AHDP and DesatArea formulation. With the AHDP formulation, regrouping was made in 52.2% of the mild OSAS cases and 62.5% of the moderate OSAS cases; by using the DesatArea calculation, 50.7% of mild OSAS cases and 63% of moderate OSAS cases were regrouped.

Conclusion

Our results show that when another parameters related to abnormal respiratory events are used, the same patients within the same group of disease severity are heterogeneously separated according to severity of hypoxia. It is suggested that grouping the patients based on AHI is insufficient and that using other polysomnographic measurements along with AHI should be considered to represent the severity of the disease.

Diastolic dysfunction in men with severe obstructive sleep apnea syndrome but without cardiovascular or oxidative stress-related comorbidities

Background:

We aimed to evaluate whether the severity of obstructive sleep apnea syndrome (OSAS) per se affects the prevalence of left ventricular (LV) diastolic dysfunction in patients without comorbidities.

Methods:

A total of 42 patients with first-diagnosed severe OSAS [apnea–hypopnea index (AHI) > 30] and 25 controls (AHI < 5), having been referred for snoring to the Sleep Laboratory Department of our tertiary Hospital, were enrolled in the study. Inclusion criteria were absence of any cardiovascular or oxidative stress-related comorbidities, and age between 20 and 70 years. Clinical, laboratory, echocardiographic, and polysomnographic data were recorded prospectively. Diastolic dysfunction diagnosis and grading was based on 2016 ASE/EACVI recommendations.

Results:

Severe OSAS was associated with significantly increased prevalence and degree of diastolic dysfunction (26/42; 61.9%) compared with controls (7/25; 28%) (p = 0.007). AHI ⩾ 55 (dichotomous value of severe OSAS subset) was also characterized by greater prevalence and degree of diastolic dysfunction compared with 30 < AHI < 55 patients (p = 0.015). In the severe OSAS subset, age >45 years-old, height <1.745 m, body-mass index (BMI) >27.76 kg m⁻², OSAS severity (AHI > 57.35), oxidative stress (overnight reduction of reduced to oxidized glutathione ratio < 18.44%), and BMI/height ratio > 16.155 kg m⁻³ (an index describing ‘dense’, short-heavy patients) presented significant diagnostic utility in identifying diastolic dysfunction in ROC-curve analysis (0.697 ⩾ AUC ⩾ 0.855, 0.001 ⩽ p ⩽ 0.018). In binary logistic regression model, advanced age (OR 1.23, 95% CI 1.025–1.477; p = 0.026) and AHI (OR 1.123, 95% CI 1.007–1.253; p = 0.036) showed independent association with diastolic dysfunction in severe OSAS.

Conclusions:

The present prospective study may suggest that severe OSAS is significantly associated with LV diastolic dysfunction; OSAS clinical severity exerts a positive influence on (and possibly constitutes an independent risk factor of) LV diastolic dysfunction.

The reviews of this paper are available via the supplementary material section.

Free Radical Oxidation and Sleep Disorders in Andro- and Menopause (Literature Review)

This review presents data on changes in the physiology of sleep during reproductive aging. It is noted that insomnia and obstructive sleep apnea syndrome (OSAS) are the main sleep disorders. The results of foreign and domestic studies in the field of free radical oxidation during sleep deprivation in animal models are presented, indicating the dependence of processes on the duration of sleep deprivation. The largest number of studies of free radical processes in a person with somnological pathology was carried out in the study of OSAS. Blood, urine, saliva, condensate of exhaled air can be biomaterial for determining the parameters of free radical oxidation. It was shown that the intensity of oxidative stress depends on the severity of OSAS, as evidenced by the positive correlation of the level of active products of thiobarbituric acid, the products of oxidation of proteins and carbonyl groups with the apnea/hypopnea index, determining the development of not only oxidative, but also carbonyl stress in patients with a severe degree OSAS. Biomarkers such as thioredoxin, malondialdehyde, superoxide dismutase, and reduced iron have shown a more stable relationship between increased oxidative stress and OSA. Despite the results obtained, the question of the association of oxidative stress and hypoxia in OSA remains debatable, which is associated with the opposite results of some studies. Insomnia, which occurs mainly in females, is accompanied by a high level of end products of lipid peroxidation with a decrease in the activity of antioxidants such as paraoxonase, an enzymatic component of the glutathione system. Along with this, menopausal women present low levels of uric acid, which correlates with high scores of the Pittsburgh sleep quality index questionnaire. Recent studies have identified an association between the activity of the «lipoperoxidation – antioxidants» system and the Clock 3111T/C gene polymorphism in menopausal Caucasian women, indicating the protective role of the minor allele.

Thiol-disulfide as a novel indicator of obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is an oxidative stress disease, which has been considered to be a notable risk and associated with increased cardiovascular morbidity and mortality. Thiol-disulfide homeostasis is as a novel indicator of oxidative stress.

OBJECTIVES

We aimed to evaluate thiol-disulfide homeostasis in a large patient population with OSA.

METHODS

A total of 230 with OSA and 40 healthy controls were included in the study. Inclusion criteria for OSA patients are having apnoea-hypopnoea index of ≥5/hour, being more than 18 years of age and having no previous treatment for OSA. Thiol-disulfide analysis was done for the patients and control group. Blood thiol-disulfide homeostasis was analysed using the new automatic method, developed by Erel and Neşelioğlu.

RESULTS

Among all OSA subjects, 149 (64.8%) were males and the mean ages of the patients were 53.38 ± 10.22. Total thiol, native thiol (SH) and disulfide (SS) levels were significantly lower in OSA group compared to the control group (P < .001, P < .001 and P = .039 respectively). Also, total thiol and native thiol (SH) were significantly different between the groups according to OSA severity (mild-moderate to severe OSA) (P < .001 and P < .001 respectively). Thiol-disulfide redox parameters were correlated with apnoea-hypopnoea index (AHI) scores.

CONCLUSION

The present prospective study showed that thiol/disulfide homeostasis was unbalanced in OSA patients. Especially, in OSA patients have low level of thiol/disulfide redox parameters when compared to healthy subjects. Evaluating thiol-disulfide homeostasis in OSA may be a contributing aspect to assessment and monitoring of the patient.

Oxidative Stress Indexes for Diagnosis of Health or Disease in Humans

Oxidative stress (OS) is the imbalance between oxidant and antioxidant molecules, in favor of oxidants, that causes aging and disease. Many studies have been published that demonstrate the relationship between OS and human health and disease; however, the following questions arise: (i) how are we sure that the OS is present in a biological process? (ii) Is the OS reported in the different investigations equivalent? (iii) What are the best oxidant and antioxidant markers for OS diagnosis? (iv) Can we establish the types and the intensity of the OS? (v) Does OS index could be useful for research and/or application in clinical medicine? In this regard, several indexes have been proposed to measure OS in humans relative to the state of health and disease, among which the following can be highlighted: Oxidative Stress Index (OSI), Tiol Ratios (-SH/TT, -SS/-SH, and-SS/TT), Glutathione Ratio (GSSG/GSH), Oxidative Stress Score (OSS), and OXY-index. Therefore, the aim of this review is to present the state of the art of knowledge about OS indexes for diagnosis of health or disease in humans. We searched for articles in English or Spanish in the PubMed/MEDLINE and Scopus electronic databases published up until May 2019. The keywords used were “oxidative stress,” “index,” and “oxidative stress index.” It was identified 11479 records in both databases, and 490 articles were analyzed. Our review suggests that all indexes analyzed allow diagnose and differentiate the OS related to human health and disease. Also, the studies on OSI, Oxy-score, and OSS indexes have proven to be reliable, practical, and with clinical utility. However, it is necessary to continue with longitudinal studies, especially assess the usefulness of the indexes in the clinical prognosis, and make comparative studies between the different indexes.

Correlation between obstructive sleep apnea and central retinal vein occlusion

To investigate the possible correlation between obstructive sleep apnea (OSA) and central retinal vein occlusion (CRVO). Thirty consecutive patients with a recent (<3mo) CRVO and an age- and sex-matched group of 30 control subjects were recruited. All subjects underwent full-night polysomnography to measure apnea-hypopnea index (AHI) and oxygen desaturation index (ODI). The average AHI and ODI were significantly higher in CRVO patients (AHI: 13.86±8.63, ODI: 9.21±4.47) than in control subjects (AHI: 8.51±6.36, ODI: 5.87±3.18; P=0.008 and 0.001 respectively). Additionally, the AHI was positively correlated with body mass index (BMI; r=0.476, P=0.017) and ODI (r=0.921, P<0.01) in both CRVO and control subjects. According to AHI scores, twenty-two (73.33%) CRVO patients had OSA and 12 (40.00%) control subjects had OSA, a difference that was statistically significant (P=0.019). OSA may be a risk factor for or a trigger of CRVO development.

Intermittent hypoxia, brain glyoxalase-1 and glutathione reductase-1, and anxiety-like behavior in mice

OBJECTIVE

Sleep apnea has been associated with anxiety, but the mechanisms of the sleep apnea-anxiety relationship are unresolved. Sleep apnea causes oxidative stress, which might enhance anxiety-like behavior in rodents. To clarify the apnea-anxiety connection, we tested the effect of intermittent hypoxia, a model of sleep apnea, on the anxiety behavior of mice.

METHODS

The rodents were exposed daily to 480 one-minute cycles of intermittent hypoxia to a nadir of 7±1% inspiratory oxygen fraction or to a sham procedure with room air. After 7 days, the mice from both groups were placed in an elevated plus maze and were video recorded for 10 min to allow analysis of latency, frequency, and duration in open and closed arms. Glyoxalase-1 (Glo1) and glutathione reductase-1 (GR1) were measured in the cerebral cortex, hippocampus, and striatum by Western blotting.

RESULTS

Compared to controls, the intermittent hypoxia group displayed less anxiety-like behavior, perceived by a statistically significant increase in the number of entries and total time spent in open arms. A higher expression of GR1 in the cortex was also observed.

CONCLUSION

The lack of a clear anxiety response as an outcome of intermittent hypoxia exposure suggests the existence of additional layers in the anxiety mechanism in sleep apnea, possibly represented by sleepiness and irreversible neuronal damage.

Effect of Acupuncture Therapy on Plasma Antidiuretic Hormone, Melatonin and Total Antioxidant Capacity Levels in Patients with Nocturia

Nocturia is a common symptom which causes sleeping disorders in the elderly. A number of studies have demonstrated that acupuncture may modulate a wide range of neuro endocrinological factors following stimulation of acupoints. We aim to examine the effect of acupuncture treatment and plasma levels of ADH, melatonin hormone and total antioxidant capacity (TAC) on nocturia patients. 28 healthy women subjects (Group I) and 27 women nocturia patients (Group II) have been joined to our study. Following a total of 10 acupuncture sessions has been applied with two sessions per week, we took blood samples from the nocturia patients (Group III). Plasma antidiuretic hormone, melatonin and TAC levels were studied by Elisa method. As a result, all of the patients responded to acupuncture treatment positively. In our study, patients with nocturnal polyuria (Group II) showed significantly low plasma antidiuretic hormone and melatonin levels in comparison to the Group I(p<0.001). Although plasma melatonin levels showed an increase by 12.35% in Group III in comparison to Group II, plasma ADH levels did not change between the two groups. Thus, it was concluded that melatonin could be beneficial for nocturia via central nervous system effect. Patients with nocturnal polyuria (Group II) plasma TAC level showed a decrease when compared with the control group (Group I). However, the plasma TAC level decreased by 9.83% following the 10th session in Group III in comparison to Group II (p=0,044). Based on our results we concluded that acupuncture treatment has a regulatory effect on plasma melatonin levels in patients with nocturia and can be used in the treatment of nocturia patients.

Chronic intermittent hypoxia exposure induces kidney injury in growing rats

OBJECTIVE

The objectives of this paper are to examine the effect of chronic intermittent hypoxia (CIH) on the morphological changes in the kidney of growing rats and to explore the mechanisms underlying the CIH-induced renal damage.

METHODS

Forty Sprague-Dawley rats were randomly divided into two groups: 2 and 4 weeks CIH groups (2IH, 4IH), and in the control group 2 and 4 weeks air-stimulated groups (2C, 4C), with 10 rats in each group. Pathological changes of renal tissue were observed by HE staining, PAS staining, and Masson staining. Real-time PCR method was used to detect the mRNA expression of HIF-1α, CuZnSOD/ZnSOD, and MnSOD in renal tissue.

RESULTS

(1) Intermittent hypoxia (IH) caused morphological damage in the kidney. Hypertrophy of epithelial cells in the kidney tubules and dilation in the glomeruli were observed under light microscope in HE and PAS stain, especially in 4IH group. Masson staining showed no significant fibrotic response in the IH groups. (2) Compared with the corresponding control groups, the levels of serum SOD were significantly lower in CIH groups, and especially in 4IH group. The mRNA expression of Cu/ZnSOD and MnSOD in CIH groups decreased significantly as compared to control groups. The mRNA levels of HIF-1α in the kidney were significantly higher in CIH groups than those in the corresponding control groups.

CONCLUSION

Oxidative stress played a critical role in renal damage by up-regulating HIF-1α transcription and down-regulating Cu/ZnSOD and MnSOD transcription after chronic intermittent hypoxia exposure in growing rats.

Atrial Fibrillation: Epidemiology, Pathophysiology, and Clinical Outcomes

The past 3 decades have been characterized by an exponential growth in knowledge and advances in the clinical treatment of atrial fibrillation (AF). It is now known that AF genesis requires a vulnerable atrial substrate and that the formation and composition of this substrate may vary depending on comorbid conditions, genetics, sex, and other factors. Population-based studies have identified numerous factors that modify the atrial substrate and increase AF susceptibility. To date, genetic studies have reported 17 independent signals for AF at 14 genomic regions. Studies have established that advanced age, male sex, and European ancestry are prominent AF risk factors. Other modifiable risk factors include sedentary lifestyle, smoking, obesity, diabetes mellitus, obstructive sleep apnea, and elevated blood pressure predispose to AF, and each factor has been shown to induce structural and electric remodeling of the atria. Both heart failure and myocardial infarction increase risk of AF and vice versa creating a feed-forward loop that increases mortality. Other cardiovascular outcomes attributed to AF, including stroke and thromboembolism, are well established, and epidemiology studies have championed therapeutics that mitigate these adverse outcomes. However, the role of anticoagulation for preventing dementia attributed to AF is less established. Our review is a comprehensive examination of the epidemiological data associating unmodifiable and modifiable risk factors for AF and of the pathophysiological evidence supporting the mechanistic link between each risk factor and AF genesis. Our review also critically examines the epidemiological data on clinical outcomes attributed to AF and summarizes current evidence linking each outcome with AF.

Sleep apnea and the subsequent risk of Parkinson's disease: a 3-year nationwide population-based study

PURPOSE

Sleep apnea (SA)-induced chronic intermittent hypoxia increases oxidative stress and inflammation, which may contribute to the pathophysiology of Parkinson's disease (PD). This study evaluated the risk of PD following SA diagnosis.

PATIENTS AND METHODS

This was a 3-year nationwide population-based matched cohort study using claims data from the National Health Insurance Research Database (NHIRD), Taiwan. We analyzed 1,944 patients diagnosed as having SA between 1997 and 2005 and a matched cohort of 9,720 non-SA patients from the NHIRD. Patients with a history of PD were excluded. Each patient was followed up for 3 years to evaluate subsequent PD development.

RESULTS

Of the 11,664 patients, 17 (0.9%) and 38 (0.4%) from the SA and matched non-SA cohorts, respectively, were subsequently diagnosed as having PD during follow-up. After adjustments for potential confounders, the SA cohort had a 1.85-fold higher risk of PD than the non-SA cohort (95% confidence interval [CI] =1.02-3.35; P=0.042). After age and sex stratification, PD development was independently associated with SA only in men (adjusted hazard ratio [HR], 2.26; 95% CI =1.11-4.63; P<0.05) and in patients aged ≥60 years (adjusted HR, 1.93; 95% CI =1.01-3.71; P<0.05).

CONCLUSION

Our study suggests that patients with SA are at an increased longitudinal risk of PD. Furthermore, age and male sex are independently associated with the risk of PD.

Oxidative Stress-induced Telomere Length Shortening of Circulating Leukocyte in Patients with Obstructive Sleep Apnea

The main mechanism of pathogenesis which causes systemic complications in obstructive sleep apnea (OSA) patients is believed to be intermittent hypoxia-induced intermediary effect and it depends on the burden of oxidative stress during sleep. We aimed to search the predictive markers which reflect the burden of systemic oxidative stress in patients with OSA and whether excessive telomere length shortening is a characteristic feature that can assess oxidative stress levels. We used quantitative PCR to measure telomere length using peripheral blood genomic DNA. Telomere lengths were compared in an age- and body mass index (BMI)-dependent manner in 34 healthy volunteers and 43 OSA subjects. We also performed reactive oxygen species assay to measure the concentration of hydrogen peroxide in the peripheral blood of healthy volunteers and OSA subjects. We found that the serum concentration of hydrogen peroxide was considerably higher in OSA patients, and that this was closely related with the severity of OSA. Significantly shortened telomere length was observed in the circulating leukocytes of the peripheral blood of OSA patients, and telomere length shortening was aggravated more acutely in an age- and BMI-dependent manner. An inverse correlation was observed between the concentration of hydrogen peroxide and the telomere length of OSA patients and excessive telomere length shortening was also linked to severity of OSA. The results provided evidence that telomere length shortening or excessive cellular aging might be distinctive in circulating leukocyte of OSA patients and may be an predictive biomarker for reflect the burden of oxidative stress in the peripheral blood of OSA patients.

Role of Oxidative Stress in the Neurocognitive Dysfunction of Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) is characterized by chronic nocturnal intermittent hypoxia and sleep fragmentations. Neurocognitive dysfunction, a significant and extraordinary complication of OSAS, influences patients' career, family, and social life and reduces quality of life to some extent. Previous researches revealed that repetitive hypoxia and reoxygenation caused mitochondria and endoplasmic reticulum dysfunction, overactivated NADPH oxidase, xanthine oxidase, and uncoupling nitric oxide synthase, induced an imbalance between prooxidants and antioxidants, and then got rise to a series of oxidative stress (OS) responses, such as protein oxidation, lipid peroxidation, and DNA oxidation along with inflammatory reaction. OS in brain could trigger neuron injury especially in the hippocampus and cerebral cortex regions. Those two regions are fairly susceptible to hypoxia and oxidative stress production which could consequently result in cognitive dysfunction. Apart from continuous positive airway pressure (CPAP), antioxidant may be a promising therapeutic method to improve partially reversible neurocognitive function. Understanding the role that OS played in the cognitive deficits is crucial for future research and therapeutic strategy development. In this paper, recent important literature concerning the relationship between oxidative stress and cognitive impairment in OSAS will be summarized and the results can provide a rewarding overview for future breakthrough in this field.

The Impact of Obstructive Sleep Apnea and Tobacco Smoking on Endothelial Function

BACKGROUND

Endothelial dysfunction has been recognized to occur in the context of obstructive sleep apnea (OSA) or tobacco smoking. However, the deleterious effect on vascular function with concurrence of both conditions is largely unknown.

OBJECTIVE

To investigate whether the concurrence of OSA and smoking poses an additive detriment to endothelial dysfunction.

METHODS

Chinese men without a history of chronic medical illness were invited to complete a questionnaire including smoking pack-year exposure, polysomnography and peripheral arterial tonometry (PAT) for endothelial function. Serum 8-isoprostane, advanced oxidation protein products (AOPP) and monocyte chemo-attractant protein-1 (MCP-1) were measured.

RESULTS

114 men were successfully enrolled. PAT ratio, adjusted for age and body mass index, correlated inversely with overall severity of OSA: apnea-hypopnea index (AHI), r = -0.160 (p = 0.092); oxygen desaturation index, r = -0.214 (p = 0.024); duration of oxygen saturation <90%, r = -0.219 (p = 0.020); and minimum oxygen saturation, r = 0.250 (p = 0.008). The PAT ratio decreased with increasing pack-year group (p = 0.018). It was lower with concurrent smoking history and moderate-severe OSA (AHI ≥15/h) compared to having one or neither factor (p = 0.011). Serum levels of 8-isoprostane and AOPP were positively related to severity of OSA, while MCP-1 correlated with smoking quantity. Multiple linear regression analyses showed that severity of intermittent hypoxia, MCP-1 and pack-year exposure were independent predictors of PAT ratio.

CONCLUSION

While OSA, in particular intermittent hypoxemia, and tobacco smoking were independent risk factors, the concurrence of moderate-severe OSA and smoking was associated with the most severe impairment in endothelial function.

Obstructive Sleep Apnoea and Atrial Fibrillation

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia and is associated with significant morbidity and mortality. Obstructive sleep apnoea (OSA) is common among patients with AF. Growing evidence suggests that OSA is associated with the initiation and maintenance of AF. This association is independent of obesity, body mass index and hypertension. OSA not only promotes initiation of AF but also has a significant negative impact on the treatment of AF. Patients with untreated OSA have a higher AF recurrence rate with drug therapy, electrical cardioversion and catheter ablation. Treatment with continuous positive airway pressure (CPAP) has been shown to improve AF control in patients with OSA. In this article, we will review and discuss the pathophysiological mechanisms of OSA that may predispose OSA patients to AF as well as the standard and emerging therapies for patients with both OSA and AF.

Diagnostic capability of biological markers in assessment of obstructive sleep apnea: a systematic review and meta-analysis

OBJECTIVE

The purpose of this systematic review is to evaluate the diagnostic value of biological markers (exhaled breath condensate, blood, salivary and urinary) in the diagnosis of OSA in comparison to the gold standard of nocturnal PSG.

METHODS

Studies that differentiated OSA from controls based on PSG results, without age restriction, were eligible for inclusion. The sample of selected studies could include studies in obese patients and with known cardiac disease. A detailed individual search strategy for each of the following bibliographic databases was developed: Cochrane, EMBASE, MEDLINE, PubMed, and LILACS. The references cited in these articles were also crosschecked and a partial grey literature search was undertaken using Google Scholar. The methodology of selected studies was evaluated using the 14-item Quality Assessment Tool for Diagnostic Accuracy Studies.

RESULTS

After a two-step selection process, nine articles were identified and subjected to qualitative and quantitative analyses. Among them, only one study conducted in children and one in adults found biomarkers that exhibit sufficiently satisfactory diagnostic accuracy that enables application as a diagnostic method for OSA.

CONCLUSION

Kallikrein-1, uromodulin, urocotin-3, and orosomucoid-1 when combined have enough accuracy to be an OSA diagnostic test in children. IL-6 and IL-10 plasma levels have potential to be good biomarkers in identifying or excluding the presence of OSA in adults.

Biomarkers associated with obstructive sleep apnea: A scoping review

The overall validity of biomarkers in the diagnosis of obstructive sleep apnea (OSA) remains unclear. We conducted a scoping review to provide assessments of biomarkers characteristics in the context of obstructive sleep apnea (OSA) and to identify gaps in the literature. A scoping review of studies in humans without age restriction that evaluated the potential diagnostic value of biological markers (blood, exhaled breath condensate, salivary, and urinary) in the OSA diagnosis was undertaken. Retained articles were those focused on the identification of biomarkers in subjects with OSA, the latter being confirmed with a full overnight or home-based polysomnography (PSG). Search strategies for six different databases were developed. The methodology of selected studies was classified using an adaptation of the evidence quality criteria from the American Academy of Pediatrics. Additionally the biomarkers were classified according to their potential clinical application. We identified 572 relevant studies, of which 117 met the inclusion criteria. Eighty-two studies were conducted in adults, 34 studies involved children, and one study had a sample composed of both adults and children. Most of the studies evaluated blood biomarkers. Potential diagnostic biomarkers were found in nine pediatric studies and in 58 adults studies. Only nine studies reported sensitivity and specificity, which varied substantially from 43% to 100%, and from 45% to 100%, respectively. Studies in adults have focused on the investigation of IL-6, TNF-α and hsCRP. There was no specific biomarker that was tested by a majority of authors in pediatric studies, and combinatorial urine biomarker approaches have shown preliminary promising results. In adults IL-6 and IL-10 seem to have a favorable potential to become a good biomarker to identify OSA.

Biomarkers to improve diagnosis and monitoring of obstructive sleep apnea syndrome: current status and future perspectives

Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent episodes of upper airway collapse associated with oxygen desaturation and sleep disruption. It is proposed that these periodic changes lead to molecular variations that can be detected by assessing serum biomarkers. Studies have identified inflammatory, oxidative, and metabolic perturbations attributable to sleep-disordered breathing. Given that OSAS is associated with increased cardiovascular and cerebrovascular morbidity, the ideal biomarker should enable timely recognition with the possibility of intervention. There is accumulating data on the utility of serum biomarkers for the evaluation of disease severity, prognosis, and response to treatment. However, current knowledge is limited by data collection techniques, disease complexity, and potential confounding factors. The current paper reviews the literature on the use of serum biomarkers in OSAS. It is concluded that the ideal serum biomarker still needs to be discovered, while caution is needed in the interpretation of hitherto available results.

Advanced oxidation protein products and ischaemia-modified albumin in obstructive sleep apnea

BACKGROUND

Several studies have shown that obstructive sleep apnea increases incidence of cardiovascular morbidity and mortality. The high systemic oxidative stress in obstructive sleep apnea has been considered as a major pathogenic mechanism leading to cardiovascular disease. Oxidative stress-related lipid and DNA oxidation in obstructive sleep apnea have been reported in the previous studies. In contrast, there is limited and contradictory information regarding protein oxidation in obstructive sleep apnea patients such as ischaemia-modified albumin and advanced oxidation protein products. Therefore, we aimed to investigate plasma ischaemia-modified albumin and advanced oxidation protein products and their correlation with total oxidative status and total antioxidative capacity in the obstructive sleep apnea patients.

METHODS

Plasma ischaemia-modified albumin, advanced oxidation protein products, total oxidative status and total antioxidative capacity were measured in 25 healthy volunteers and 59 obstructive sleep apnea patients diagnosed with polysomnography.

RESULTS

Plasma total antioxidative capacity was significantly lower (P = 0·012) and total oxidative status was significantly higher (P < 0·001) in the patients compared to the controls demonstrating increased oxidative stress in the patients. Plasma advanced oxidation protein products were significantly higher in the patients than the controls (P = 0·024). Plasma ischaemia-modified albumin levels were not statistically different between the obstructive sleep apnea patients and controls (P = 0·74).

CONCLUSIONS

We conclude that high systemic oxidative stress in obstructive sleep apnea is reflected by increased advanced oxidation protein products without causing an increase in ischaemia-modified albumin.

Inflammatory lung disease in Rett syndrome

Rett syndrome (RTT) is a pervasive neurodevelopmental disorder mainly linked to mutations in the gene encoding the methyl-CpG-binding protein 2 (MeCP2). Respiratory dysfunction, historically credited to brainstem immaturity, represents a major challenge in RTT. Our aim was to characterize the relationships between pulmonary gas exchange abnormality (GEA), upper airway obstruction, and redox status in patients with typical RTT (n = 228) and to examine lung histology in a Mecp2-null mouse model of the disease. GEA was detectable in ~80% (184/228) of patients versus ~18% of healthy controls, with “high” (39.8%) and “low” (34.8%) patterns dominating over “mixed” (19.6%) and “simple mismatch” (5.9%) types. Increased plasma levels of non-protein-bound iron (NPBI), F₂-isoprostanes (F₂-IsoPs), intraerythrocyte NPBI (IE-NPBI), and reduced and oxidized glutathione (i.e., GSH and GSSG) were evidenced in RTT with consequently decreased GSH/GSSG ratios. Apnea frequency/severity was positively correlated with IE-NPBI, F₂-IsoPs, and GSSG and negatively with GSH/GSSG ratio. A diffuse inflammatory infiltrate of the terminal bronchioles and alveoli was evidenced in half of the examined Mecp2-mutant mice, well fitting with the radiological findings previously observed in RTT patients. Our findings indicate that GEA is a key feature of RTT and that terminal bronchioles are a likely major target of the disease.

The DJ-1 protein as a candidate biomarker in obstructive sleep apnea syndrome

BACKGROUND

Oxidative stress has a central role in the pathophysiology of obstructive sleep apnea syndrome (OSAS). The DJ-1 protein functions as a sensor of oxidative stress, acting both as a reactive oxygen species scavenger (ROS) and an antioxidative response regulator. The aim of our study is to determine the serum levels of DJ-1 in OSAS patients and assess possible correlations with their clinical, demographical, and biochemical characteristics.

METHODS

The study included 120 subjects from the Sleep Disorder Laboratory of the University Hospital of Thessaly (100 males vs 20 females, mean age 48±10, Apnea-Hypopnea Index (AHI)>5 episodes per hour of sleep). Subjects underwent full-night polysomnography (PSG) followed by morning blood sampling. Serum DJ-1 levels were determined via ELISA kits. Statistical analysis was performed using SPSS 19.

RESULTS

The median DJ-1 levels were 56.7 ng/mL (IQR, 34.9-99.3 ng/mL). Statistically significant correlations were detected between DJ-1's levels and AHI (Spearman's rho=0.189, P=0.04), Desaturation Index (DI; Spearman's rho=0.239, P=0.012), and serum low-density lipoprotein (LDL) (Spearman's rho=-0.205, P=0.042).

CONCLUSIONS

DJ-1 may be a useful biomarker in OSAS due to its correlations with AHI and DI. The correlation with serum LDL warrants further investigation regarding possible implications in OSAS patients' cardiovascular comorbidities.

Salivary markers of oxidative stress in patients with obstructive sleep apnea treated with continuous positive airway pressure

PURPOSE

Obstructive sleep apnea syndrome (OSAS) is characterized by elevated oxidative stress. Measurement of oxidative stress in saliva seems to be promising in long-term treatment monitoring of OSAS patients. In this study, our aim was to investigate whether short-term continuous positive airway pressure (CPAP) treatment would influence oxidative stress in saliva.

METHODS

Patients with diagnosed OSAS (16 women, 28 men) underwent polysomnography during the first night and CPAP treatment during the second night. Saliva samples were taken in the evening and morning on both days. Markers of oxidative stress and antioxidant status were analyzed in saliva.

RESULTS

Evening concentrations of the salivary thiobarbituric acid reacting substances (p < 0.001), advanced glycation end-products (p < 0.001), and advanced oxidation protein products (p < 0.01) were significantly lower than morning values during the diagnostic night. However, salivary concentrations of none of the oxidative stress markers were significantly influenced by the CPAP treatment. No changes in salivary antioxidant status after CPAP therapy were found.

CONCLUSION

Salivary markers of oxidative stress and antioxidant status do not change significantly after one night treatment with CPAP. On the contrary, after 1 month with CPAP therapy, reduced markers of oxidative stress were reported. Therefore, the future studies should be focused on finding the optimal sampling frequency to clarify the potential of saliva for the monitoring of OSAS treatment.

Barrett's esophagus and the risk of obstructive sleep apnea: a case-control study

BACKGROUND

Prior studies suggest that obstructive sleep apnea may be associated with gastroesophageal reflux disease, a strong risk factor for Barrett's esophagus. The goals of this pilot case-control study were to determine whether Barrett's esophagus patients have an increased likelihood of obstructive sleep apnea and to determine whether nocturnal gastroesophageal reflux symptoms affect the relationship between Barrett's esophagus and obstructive sleep apnea risk.

METHODS

Patients with Barrett's esophagus completed the Berlin Questionnaire, a validated survey instrument identifying subjects at high risk for obstructive sleep apnea. Two outpatient control groups were recruited: 1) EGD Group, subjects matched to Barrett's esophagus cases by age, race, and gender with esophagogastroduodenoscopy negative for Barrett's esophagus; and 2) Colonoscopy Group, patients getting colonoscopy. Rates of scoring at high risk for obstructive sleep apnea were compared. Respondents were also questioned regarding severity of their typical gastroesophageal reflux symptoms and presence of nocturnal gastroesophageal reflux symptoms.

RESULTS

The study included 287 patients (54 Barrett's esophagus, 62 EGD, and 171 colonoscopy subjects). Barrett's esophagus patients were slightly older than colonoscopy patients and more obese. 56% (n = 30) of Barrett's esophagus subjects scored at high risk for obstructive sleep apnea, compared with 42% (n = 26) of EGD subjects (OR 1.73, 95% CI [0.83, 3.62]) and 37% (n = 64) of colonoscopy patients (OR 2.08, 95% CI [1.12, 3.88]). The association between Barrett's esophagus and scoring at high risk for obstructive sleep apnea compared with colonoscopy patients disappeared after adjusting for age. Barrett's esophagus patients reported more severe typical heartburn and regurgitation symptoms than either control group. Among all subjects, patients with nocturnal reflux symptoms were more likely to score at high risk for obstructive sleep apnea than patients without nocturnal reflux.

CONCLUSIONS

In this pilot study, a high proportion of Barrett's esophagus subjects scored at high risk for obstructive sleep apnea. Having Barrett's esophagus was associated with more severe gastroesophageal reflux symptoms, and nocturnal reflux symptoms were associated with scoring at high risk for obstructive sleep apnea. The need for obstructive sleep apnea screening in Barrett's esophagus patients with nocturnal gastroesophageal reflux symptoms should be further evaluated.

Blood trace minerals concentrations and oxidative stress in patients with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is associated with increased oxidative stress. Certain essential trace minerals have shown to play an important role in the maintenance of redox homeostasis. We determined the concentrations of trace minerals in OSA patients and assessed their relationships to OSA severity as indicated by the apnea/ hypopnea index (AHI).

METHODS

We enrolled 44 patients with newly diagnosed mild to moderate OSA and 20 without OSA. The following parameters were measured: polysomnographic values of nocturnal sleep; plasma trace minerals zinc (Zn), copper (Cu), iron (Fe), and erythrocyte selenium (Se); oxidative stress status; and plasma high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor-α (TNF-α).

RESULTS

Compared to controls matched for age, gender, and body mass index, OSA patients had lower concentrations of plasma Zn and erythrocyte Se and higher plasma concentrations of Cu and Fe. OSA patients had significantly higher plasma concentrations of hs-CRP, TNF-α, and malondialdehyde (MDA), and lower erythrocyte antioxidant enzyme glutathione peroxidase (GPx) and superoxide dismutase activities. Significant differences in all the above parameters were also found in patients with moderate OSA compared to those with mild OSA. Furthermore, AHI values correlated significantly with neck circumference, GPx activity, and MDA, hs-CRP, and TNF-α concentrations in OSA patients. AHI values were also negatively associated with concentrations of plasma Zn and erythrocyte Se, but were positively linked to plasma concentrations of Fe and Cu.

CONCLUSIONS

Abnormal concentrations of these trace minerals may reflect oxidative damage and inflammatory response, thus increasing the severity of OSA.