Endothelial cell apoptosis in obstructive sleep apnea: a link to endothelial dysfunction

The Effect of Continuous Positive Airway Pressure (CPAP) Therapy on Serum Caspase-3 Level in Patients with Obstructive Sleep Apnea (OSA)

INTRODUCTION

Intermittent hypoxemia has an important role in the physiopathogenesis of obstructive sleep apnea (OSA) complications. Increased apoptosis due to intermittent hypoxemia may be an important clinical entity in OSA. In this study, we aimed to evaluate caspase-3 enzyme level, which is an indirect marker of increased apoptosis in patients with OSA and to evaluate the effect of OSA treatment with continuous positive airway pressure on caspase-3 enzyme level.

MATERIALS AND METHODS

This study included 141 consecutive patients admitted to the sleep-disordered breathing laboratory within 6 months. Caspase-3 was measured in routine blood samples obtained on the morning of polysomnography (PSG) performed at night. The compliance of the patients to CPAP treatment was evaluated and caspase-3 levels were checked again after treatment.

RESULTS

A total of 141 patients, 39 females (27,7%) and 102 males (72,3%) were included in the study. The mean age of the patients was 49 ± 12 years (min-17, max-77). According to PSG results, OSA was detected in 95.7% (135/141) of the cases. Mild OSA was 35 (24.8%), moderate OSA 39 (27.7%) and severe OSA 61 (43.3%) cases. Median caspase-3 enzyme levels were similar in men and women in the study group. There was no statistically significant difference in hemogram parameters and caspase-3 enzyme levels between the groups divided according to the presence and severity of OSA. It was determined that caspase-3 enzyme level did not change significantly after 3 months of CPAP treatment in OSA compared to pretreatment. Caspase-3 was found to have a negative correlation with both the percentage of daily use of CPAP therapy and the percentage of CPAP device use for more than 1 h per night. It was found that the control caspase-3 level decreased statistically significantly as the percentage of daily use of CPAP therapy increased (r = -0.397, p = 0.030). It was found that the control caspase-3 level decreased statistically significantly as the percentage of CPAP therapy use for more than 1 h per night increased (r = -0.411, p = 0.024).

CONCLUSION

The results of this study did not reveal a relationship between the severity of OSA and caspase-3 levels. However, blood caspase-3 levels decreased as treatment compliance increased, suggesting that CPAP treatment may correct increased apoptosis in OSA. There is a need for more comprehensive studies on this issue.

Obstructive sleep apnea hypopnea syndrome and vascular lesions: An update on what we currently know

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is the most prevalent sleep and respiratory disorder. This syndrome can induce severe cardiovascular and cerebrovascular complications, and intermittent hypoxia is a pivotal contributor to this damage. Vascular pathology is closely associated with the impairment of target organs, marking a focal point in current research. Vascular lesions are the fundamental pathophysiological basis of multiorgan ailments and indicate a shared pathogenic mechanism among common cardiovascular and cerebrovascular conditions, suggesting their importance as a public health concern. Increasing evidence shows a strong correlation between OSAHS and vascular lesions. Previous studies predominantly focused on the pathophysiological alterations in OSAHS itself, such as intermittent hypoxia and fragmented sleep, leading to vascular disruptions. This review aims to delve deeper into the vascular lesions affected by OSAHS by examining the microscopic pathophysiological mechanisms involved. Emphasis has been placed on examining how OSAHS induces vascular lesions through disruptions in the endothelial barrier, metabolic dysregulation, cellular phenotype alterations, neuroendocrine irregularities, programmed cell death, vascular inflammation, oxidative stress and epigenetic modifications. This review examines the epidemiology and associated risk factors for OSAHS and vascular diseases and subsequently describes the existing evidence on vascular lesions induced by OSAHS in the cardiovascular, cerebrovascular, retinal, renal and reproductive systems. A detailed account of the current research on the pathophysiological mechanisms mediating vascular lesions caused by OSAHS is provided, culminating in a discussion of research advancements in therapeutic modalities to mitigate OSAHS-related vascular lesions and the implications of these treatment strategies.

Diagnostic Role of Circulating Endocan Levels in Obstructive Sleep Apnea: A Systematic Review and Meta-Analysis

Endocan, as an endothelial cell damage marker, plays role in several cardiovascular and non-cardiovascular diseases. This systematic review and meta-analysis evaluates the role of endocan as a potential diagnostic or prognostic biomarker for obstructive sleep apnea (OSA). International databases including PubMed, Embase, Web of Science, and Scopus were searched for relevant studies assessing endocan levels in OSA patients compared with healthy controls or within different severities or comorbidities of OSA. Random-effect meta-analysis was performed in order to calculate the standardized mean difference (SMD) and 95% confidence interval (CI) of serum/plasma endocan in all comparisons. A total of 10 studies were included in our systematic review, among which seven were used in meta-analysis. Meta-analysis showed that endocan levels were significantly higher in patients with OSA compared with healthy controls (SMD 1.29, 95% CI 0.64-1.93, P < .001) and this was not different between serum and plasma subgroups. However, there was no statistical difference between severe and non-severe OSA patients (SMD .64, 95% CI -.22 to 1.50, P = .147). Considerably, higher endocan levels in patients with OSA in comparison with non-OSA individuals might have clinical implications. This association warrants further research due to its potential use as a diagnostic and prognostic biomarker.

Coagulation and Fibrinolysis in Obstructive Sleep Apnoea

Obstructive sleep apnoea (OSA) is a common disease which is characterised by repetitive collapse of the upper airways during sleep resulting in chronic intermittent hypoxaemia and frequent microarousals, consequently leading to sympathetic overflow, enhanced oxidative stress, systemic inflammation, and metabolic disturbances. OSA is associated with increased risk for cardiovascular morbidity and mortality, and accelerated coagulation, platelet activation, and impaired fibrinolysis serve the link between OSA and cardiovascular disease. In this article we briefly describe physiological coagulation and fibrinolysis focusing on processes which could be altered in OSA. Then, we discuss how OSA-associated disturbances, such as hypoxaemia, sympathetic system activation, and systemic inflammation, affect these processes. Finally, we critically review the literature on OSA-related changes in markers of coagulation and fibrinolysis, discuss potential reasons for discrepancies, and comment on the clinical implications and future research needs.

Recent Advances in Studies on the Role of Neuroendocrine Disorders in Obstructive Sleep Apnea-Hypopnea Syndrome-Related Atherosclerosis

Cardiovascular disease is a common cause of death worldwide, and atherosclerosis (AS) and obstructive sleep apnea-hypopnea syndrome (OSAHS) critically contribute to the initiation and progression of cardiovascular diseases. OSAHS promotes endothelial injury, vascular smooth muscle cell (VSMC) proliferation, abnormal lipid metabolism, and elevated arterial blood pressure. However, the exact OSAHS mechanism that causes AS remains unclear. The nervous system is widely distributed in the central and peripheral regions. It regulates appetite, energy metabolism, inflammation, oxidative stress, insulin resistance, and vasoconstriction by releasing regulatory factors and participates in the occurrence and development of AS. Studies showed that OSAHS can cause changes in neurophysiological plasticity and affect modulator release, suggesting that neuroendocrine dysfunction may be related to the OSAHS mechanism causing AS. In this article, we review the possible mechanisms of neuroendocrine disorders in the pathogenesis of OSAHS-induced AS and provide a new basis for further research on the development of corresponding effective intervention strategies.

Sleep-disordered breathing does not impact maternal outcomes in women with hypertensive disorders of pregnancy

Objective

Sleep-disordered breathing (SDB) is characterised by intermittent hypoxemia, sympathetic activation and widespread endothelial dysfunction, sharing pathophysiologic features with the hypertensive disorders of pregnancy. We sought to determine whether coexisting SDB would adversely impact the outcomes of women with gestational hypertension (GH) and preeclampsia (PE), and healthy matched controls.

Study design

Women diagnosed with GH or PE along with BMI- and gestation-matched normotensive controls underwent polysomnography in late pregnancy to establish the presence or absence of SDB (RDI ≥ 5). Clinical outcomes of hypertensive disease severity were compared between groups, and venous blood samples were taken in the third trimester and at delivery to examine for any impact of SDB on the anti-angiogenic markers of PE.

Results

Data was available for 17 women with PE, 24 women with GH and 44 controls. SDB was diagnosed in 41% of the PE group, 63% of the GH group and 39% of the control group. Women with PE and co-existing SDB did not have worse outcomes in terms of gestation at diagnosis of PE (SDB = 29.1 (25.9, 32.1) weeks vs. no SDB = 32.0 (29.0, 33.9), p = n.s.) and days between diagnosis of PE and delivery (SDB = 20.0 (4.0, 35.0) days vs. no SDB = 10.5 (9.0, 14.0), p = n.s.). There were also no differences in severity of hypertension, antihypertensive treatment and biochemical, haematological and anti-angiogenic markers of PE between SDB and no SDB groups. Similar results were observed among women with GH. Healthy control women with SDB were no more likely to develop a hypertensive disorder of pregnancy in the later stages of pregnancy (SDB = 5.9% vs. no SDB = 7.4%, p = n.s.). Increasing the threshold for diagnosis of SDB to RDI ≥ 15 did not unmask a worse prognosis.

Conclusion

The presence of SDB during pregnancy did not worsen the disease course of GH or PE, and was not associated with high blood pressure or anti-angiogenic markers of hypertensive disease amongst healthy pregnant women. Given the numerous reports of the relationship between SDB and diagnosis of hypertensive disorders of pregnancy, it appears more work is required to distinguish causal, versus confounding, pathways.

The Relationship Between Obstructive Sleep Apnea and Ruptured Intracranial Aneurysms

STUDY OBJECTIVES

The role of obstructive sleep apnea (OSA) in the overall outcome of ruptured intracranial aneurysms (RIAs) is unknown. We have investigated the role of OSA in overall outcome of RIAs.

METHODS

Data from 159 consecutive patients were retrospectively reviewed. A chi-square test and regression analysis were performed to determine the significant difference. A value of P < .05 was considered significant.

RESULTS

The prevalence of OSA in RIAs was fivefold higher in the nonaneurysm patient group, P = .002. The number of patients with hypertension (P < .0001), body mass index ≥ 30 (P < .0001), hyperlipidemia (P = .018), chronic heart disease (P = .002) or prior ischemic stroke (P = .001) was significantly higher in the OSA group. Similarly, the number of wide-neck aneurysms (P < .0001) and aneurysm > 7 mm (P = .004), poor Hunt and Hess grade IV-V (P = .005), vasospasms, (P = .03), and patients with poor Modified Rankin Scale scores (3-6) was significantly higher in the OSA group (P < .0001). Interestingly, for the first time in univariate (P = .01) and multivariate (P = .003) regression analysis, OSA was identified as an individual predictor of unfavorable outcome of RIAs. In addition, hypertension (P = .04), smoking (P = .049), chronic heart disease (P = .01), and Hunt and Hess grade IV-V (P = .04) were revealed as predictors of poor outcome of RIAs.

CONCLUSIONS

This is a novel study to determine the association between OSA and ruptured cerebral aneurysm in terms of comorbidities, size of aneurysm, severity of symptoms, and outcomes after treatment. In addition, for the first time, OSA is identified as a positive predictor of unfavorable outcome of RIAs.

Hematological indices as simple, inexpensive and practical severity markers of obstructive sleep apnea syndrome: a meta-analysis

Background

Clinical detection of inflammatory markers is useful to assess the degree of nocturnal hypoxia and predict the presence of complications in obstructive sleep apnea syndrome (OSAS) patients. Nowadays, some researchers proposed that hematological parameters could be substituted for novel disease-specific biochemical markers (such as C-reactive protein) because they were comparatively cheap, simple and practical. But there was a contradiction whether the hematological parameters were positively correlated with the OSAS severity.

Methods

Medical databases were searched included PubMed, Web of Science, Scopus, Cochrane Library, Clinical Trial, Embase and Google Scholar (up to March 29, 2018). We used weighted mean differences (WMDs) with 95% confidence intervals (CIs) from random-effects model.

Results

Seventeen studies were included in this meta-analysis and results were presented by different hematological parameters. Pooled analysis showed that OSAS was associated with a high level of WBC (white blood cell, 11 studies, 2,206 subjects, WMD: 0.58; 95% CI: 0.31 to 0.85; P<0.0001), NLR (neutrophil-to-lymphocyte ratio, 5 studies, 1416 subjects, WMD: 0.46; 95% CI: 0.13 to 0.80; P=0.007), MPV (mean platelet volume, 8 studies, 1,854 subjects, WMD: 0.63; 95% CI: 0.29 to 0.98; P=0.0004), PDW (platelet distribution width, 6 studies, 1,911 subjects, WMD: 0.76; 95% CI: 0.47 to 1.06; P<0.00001), PLR (platelet-to-lymphocyte ratio, 3 studies, 998 subjects, WMD: 21.76; 95% CI: 8.54 to 34.99; P=0.001), RDW (red cell distribution width, 5 studies, 1,701 subjects, WMD: 0.31; 95% CI: 0.11 to 0.51; P=0.002) and HCT (hematocrit, 3 studies, 662 subjects, WMD: 1.58; 95% CI: 0.52 to 2.64; P=0.003). But OSAS was associated with a low level of LYM (lymphocyte, 5 studies, 1,285 subjects, WMD: -0.27; 95% CI: -0.49 to -0.06; P=0.01). There was a gradual rising trend from mild OSAS to severe OSAS existed in all subgroups.

Conclusions

Hematological indices are comparatively Simple, Inexpensive and Practical Severity Markers of OSAS including WBC, LYM, NLR, MPV, PDW, PLR, RDW and HCT.

Effects of Antioxidant Tempol on Systematic Inflammation and Endothelial Apoptosis in Emphysematous Rats Exposed to Intermittent Hypoxia

PURPOSE

Obstructive sleep apnea and chronic obstructive pulmonary disease are independent risk factors of cardiovascular disease (CVD), and their coexistence is known as overlap syndrome (OS). Endothelial dysfunction is the initial stage of CVD; however, underlying mechanisms linking OS and CVD are not well understood. The aim of this study was to explore whether OS can lead to more severe inflammation and endothelial apoptosis by promoting endothelial dysfunction, and to assess the intervention effects of antioxidant tempol.

MATERIALS AND METHODS

Male Wistar rats (n=66) were exposed to normal oxygen [normal control (NC) group], intermittent hypoxia (IH group), cigarette smoke (CH group), as well as cigarette smoke and IH (OS group). Tempol intervention was assessed in OS group treated with tempol (OST group) or NaCl (OSN group). After an 8-week challenge, lung tissues, serum, and fresh blood were harvested for analysis of endothelial markers and apoptosis.

RESULTS

The levels of intracellular adhesion molecule-1, vascular cellular adhesion molecule-1, and apoptosis in circulating epithelial cells were the highest in OS group and the lowest in NC group. These levels were all greater in IH group than in CH group, and were lower in OST group than in OS and OSN groups (all p<0.001).

CONCLUSION

Synergistic effects of IH with cigarette smoke-induced emphysema produce a greater inflammatory status and endothelial apoptosis. OS-related inflammation and endothelial cell apoptosis may play important roles in promoting cardiovascular dysfunction, and antioxidant tempol could achieve a partial protective effect.

Protective Effects of Rhodiola Crenulata Extract on Hypoxia-Induced Endothelial Damage via Regulation of AMPK and ERK Pathways

Rhodiola crenulata root extract (RCE) has been shown to possess protective activities against hypoxia both in vitro and in vivo. However, the effects of RCE on response to hypoxia in the endothelium remain unclear. In this study, we aimed to examine the effects of RCE in endothelial cells challenged with hypoxic exposure and to elucidate the underlying mechanisms. Human umbilical vein endothelial cells were pretreated with or without RCE and then exposed to hypoxia (1% O₂) for 24 h. Cell viability, nitric oxide (NO) production, oxidative stress markers, as well as mechanistic readouts were studied. We found that hypoxia-induced cell death, impaired NO production, and oxidative stress. These responses were significantly attenuated by RCE treatment and were associated with the activation of AMP-activated kinase and extracellular signal-regulated kinase 1/2 signaling pathways. In summary, we showed that RCE protected endothelial cells from hypoxic insult and suggested that R. crenulata might be useful for the prevention of hypoxia-associated vascular dysfunction.

Cardiorespiratory interaction with continuous positive airway pressure

The treatment of choice for obstructive sleep apnoea (OSA) is continuous positive airway pressure therapy (CPAP). Since its introduction in clinical practice, CPAP has been used in various clinical conditions with variable and heterogeneous outcomes. In addition to the well-known effects on the upper airway CPAP impacts on intrathoracic pressures, haemodynamics and blood pressure (BP) control. However, short- and long-term effects of CPAP therapy depend on multiple variables which include symptoms, underlying condition, pressure used, treatment acceptance, compliance and usage. CPAP can alter long-term cardiovascular risk in patients with cardiorespiratory conditions. Furthermore, the effect of CPAP on the awake patient differs from the effect on the patients while asleep, and this might contribute to discomfort and removal of the use interface. The purpose of this review is to highlight the physiological impact of CPAP on the cardiorespiratory system, including short-term benefits and long-term outcomes.

Omentin-A Novel Adipokine in Respiratory Diseases

Adipokines, secreted by the adipose tissue, are extensively involved in the regulation and maintenance of various physiological and pathological processes, including insulin sensitivity, energy expenditure, glucose and lipid metabolism, inflammatory activity, neuroendocrine activity, immunity, cancer, homeostasis, angiogenesis, cardiovascular function, breeding and bone metabolism, and all functions of the endocrine-reproductive system axis. Omentin is a recently identified adipokine, which has become a research hotspot due to its pleiotropic effects on various diseases. However, the specific receptor for omentin has not been identified so far. In this study, we report that omentin levels fluctuate in various diseases. In addition, we have focused on the pleiotropic roles of omentin in pulmonary diseases, as it may act as a biomarker for malignant pleural mesothelioma (MPM) and is related to disease severity. Omentin may play significant roles in other pulmonary diseases, such as asthma, obstructive sleep apnea syndrome (OSAS), pulmonary arterial hypertension (PAH), acute respiratory distress syndrome (ARDS), and chronic obstructive pulmonary disease (COPD). This review summarizes the advances in current knowledge and future trends, which may provide a concise and general view on omentin and its effects on pulmonary biology.

Estradiol Regulates Txnip and Prevents Intermittent Hypoxia-Induced Vascular Injury

Chronic intermittent hypoxia (IH) contributes to obstructive sleep apnea (OSA)-related cardiovascular diseases through increasing oxidative stress. It has been widely recognized that estradiol decreases the risk for cardiovascular disease, but the estrogen replacement therapy is limited for its side effects. Thioredoxin (Trx) and its endogenous inhibitor, thioredoxin-interacting protein (Txnip), are associated with the protective effect of estradiol in some conditions. In this study, we aimed to explore whether estradiol could protect against IH-induced vascular injury, and the possible effect of Trx-1/Txnip in this process. Forty-eight adult female C57/BL6J mice were randomly divided into 4 groups, ovariectomy combined with IH group, sham operation combined with IH group, IH group and the control group. The mice treated with IH for 8 hrs/day, and 28 days. IH induced the injury of aorta, and ovariectomized mice were more prone to the IH-induced aortic injury, with higher level of oxidative stress. In vitro, estradiol increased Trx-1 level, but decreased the level of Txnip and oxidative stress in human umbilical vein endothelial cells (HUVECs) treated with IH for 16 hrs. Knock-down of Txnip by specific siRNA rescued oxidative stress and apoptosis. In conclusion, estradiol protects against IH-induced vascular injury, partially through the regulation of Trx-1/Txnip pathway.

The efficacy of continuous positive airway pressure therapy in reducing cardiovascular events in obstructive sleep apnea: a systematic review

Prospective studies show an association between obstructive sleep apnea and cardiovascular disease. Continuous positive airway pressure (CPAP) is the treatment of choice and effectively reduces subjective sleepiness and apneic and hypopneic events. However, randomized trials have not shown a reduction in cardiovascular outcomes with CPAP therapy. We review the past 10 years of randomized trial evidence regarding the therapeutic efficacy of CPAP on cardiovascular outcomes and mortality in adults with obstructive sleep apnea. The majority of studies found no significant improvement in cardiovascular outcomes with CPAP, although many noted nonsignificant benefits. Adjusted analysis in several trials showed significant cardiovascular benefit in those patients with higher CPAP compliance. Existing trials may lack sufficient follow-up and CPAP compliance, among other limitations.

Coexistence of obstructive sleep apnea worsens the overall outcome of intracranial aneurysm: a pioneer study

OBJECTIVE Obstructive sleep apnea (OSA) is associated with the progression of abdominal and thoracic aortic aneurysms. However, the role of OSA in the overall outcome of intracranial aneurysms (IAs) has not yet been established. Authors of this report investigated the role of OSA in the overall outcome of IAs. METHODS Radiological and clinical data on patients (from 2010 through 2015) with confirmed IA were retrospectively reviewed. Significant differences between the OSA and non-OSA groups were determined using a chi-square test. Logistic regression analysis was performed to identify the predictors of an unfavorable IA outcome. RESULTS Among the 283 patients with confirmed IAs, 45 patients (16%) were positively screened for OSA, a proportion that was significantly higher than the prevalence of OSA in nonaneurysmal neurosurgical patients (4%, p = 0.008). The percentage of patients with hypertension (p = 0.018), a body mass index ≥ 30 kg/m² (p < 0.0001), hyperlipidemia (p = 0.034), diabetes mellitus (p = 0.005), chronic heart disease (CHD; p = 0.024), or prior stroke (p = 0.03) was significantly higher in the OSA group than in the non-OSA group. Similarly, the percentage of wide-necked aneurysms (p = 0.00001) and patients with a poor Hunt and Hess Grade IV-V (p = 0.01) was significantly higher in the OSA group than in the non-OSA group. In addition, the percentage of ruptured aneurysms (p = 0.03) and vasospasms (p = 0.03) was significantly higher in the OSA group. The percentage of patients with poor modified Rankin Scale (mRS) scores (3-6) was significantly higher in the OSA group (p = 0.03). A separate cohort of patients with ruptured IAs showed similar results. In both univariate (p = 0.01) and multivariate (p = 0.04) regression analyses, OSA was identified as an individual predictor of an unfavorable outcome. In addition, hypertension and prior stroke were revealed as predictors of a poor IA outcome. CONCLUSIONS Complications of IA such as rupture and vasospasm are often the consequence of uncontrolled OSA. Overall outcome (mRS) of IAs is also affected by the co-occurrence of OSA. Therefore, the coexistence of OSA with IA affects the outcome of IAs. Obstructive sleep apnea is a risk factor for a poor outcome in IA patients.

Patients with Obstructive Sleep Apnea Display Decreased Flow-Mediated Dilatation: Evidence from a Meta-Analysis

Background

Endothelial dysfunction, which can be measured by flow-mediated dilatation (FMD), is an early clinical marker of atherosclerosis, which is considered to be the main cause of the observed cardiovascular complications in obstructive sleep apnea (OSA) patients. The association between OSA and endothelial dysfunction has been reported in a number of studies; however, the findings are not entirely consistent. Our aim was to meta-analytically synthesize the existing evidence to explore the association between OSA and endothelial dysfunction.

Material/Methods

Data from PubMed, EMBASE, the Cochrane library, and Google Scholar for all trials that investigated the relationship between endothelial dysfunction and OSA were systematically reviewed. The minimum inclusion criteria for the studies were reporting of the Apnea-Hypopnea Index (AHI) and FMD measurements (as an indicator of endothelial dysfunction) for both OSA and control groups. Data from case-control studies that met the inclusion criteria were extracted.

Results

Twenty-eight studies comprising a total of 1496 OSA patients and 1135 controls were included in the meta-analysis. A random-effects model was used. The weighted mean difference in the FMD measurements was −3.07 and the 95% confidence interval was −3.71 to −2.43 (P<0.01). Meta-regression analysis showed that age, sex, body mass index (BMI), blood pressure, glucose, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol did not explain the heterogeneity.

Conclusions

This meta-analysis showed that patients with OSA have decreased FMD, which may contribute to the development of atherosclerosis.

Erythrocyte deformability, plasma lipid peroxidation and plasma protein oxidation in a group of OSAS subjects

Considering that obstructive sleep apnea syndrome (OSAS) is usually associated with endothelial dysfunction, atherosclerosis and cardiovascular disorders, our aim was to examine the erythrocyte deformability and the oxidative status in a group of OSAS subjects. We consecutively enrolled 48 subjects with OSAS defined after a 1-night cardiorespiratory sleep study, subsequently subdivided according to the apnea/hypopnea index (AHI) value in two subgroups: Low (L = 21 subjects with AHI<30) and High (H = 27 subjects with AHI>30). We evaluated the erythrocyte deformability, expressed as elongation index (EI) and the parameters of the oxidative status, such as lipid peroxidation (expressed as thiobarbituric acid-reactive substances - TBARS) and protein oxidation (measured as carbonyl groups - PC). In the entire group and in the two subgroups of OSAS subjects we found a decreased erytrocyte deformability at all shear stresses, not correlated with the plasmatic oxidative stress nor with the polysomnographic parameters. Lipid peroxidation was increased in the whole group and in the H subgroup of OSAS while protein oxidation showed a different trend. As in OSAS the osmotic fragility and the metabolism of the red cells seem to be not impaired, the oxidative damage to the red cell membrane proteins might be responsible for the reduced erythrocyte deformability. This rheological alteration, in addition to the increase in whole blood and plasma viscosity and to the erythrocyte hyperaggregation, could influence the microcircolatory profile in OSAS subjects.

Roles and Mechanisms of Obstructive Sleep Apnea-Hypopnea Syndrome and Chronic Intermittent Hypoxia in Atherosclerosis: Evidence and Prospective

The morbidity and mortality of obstructive sleep apnea-hypopnea syndrome (OSAHS) are regarded as consequences of its adverse effects on the cardiovascular system. Chronic intermittent hypoxia (CIH) induced by OSAHS can result in vascular endothelial injury, thus promoting development of atherosclerosis (AS). Studies have shown that CIH is an independent risk factor for the occurrence and development of AS, but the underlying mechanism remains unclear. Here, we review clinical and fundamental studies reported during the last 10 years on the occurrence and development of AS mediated by CIH, focusing on inflammation, oxidative stress, insulin resistance, cell apoptosis, vascular endothelial injury, platelet activation, and neuroendocrine disorders. This review will offer current evidence and perspective to researchers for the development of effective intervention strategies for OSAHS-related cardiocerebrovascular diseases.

Hypoxia: The Force that Drives Chronic Kidney Disease

In the United States the prevalence of end-stage renal disease (ESRD) reached epidemic proportions in 2012 with over 600,000 patients being treated. The rates of ESRD among the elderly are disproportionally high. Consequently, as life expectancy increases and the baby-boom generation reaches retirement age, the already heavy burden imposed by ESRD on the US health care system is set to increase dramatically. ESRD represents the terminal stage of chronic kidney disease (CKD). A large body of evidence indicating that CKD is driven by renal tissue hypoxia has led to the development of therapeutic strategies that increase kidney oxygenation and the contention that chronic hypoxia is the final common pathway to end-stage renal failure. Numerous studies have demonstrated that one of the most potent means by which hypoxic conditions within the kidney produce CKD is by inducing a sustained inflammatory attack by infiltrating leukocytes. Indispensable to this attack is the acquisition by leukocytes of an adhesive phenotype. It was thought that this process resulted exclusively from leukocytes responding to cytokines released from ischemic renal endothelium. However, recently it has been demonstrated that leukocytes also become activated independent of the hypoxic response of endothelial cells. It was found that this endothelium-independent mechanism involves leukocytes directly sensing hypoxia and responding by transcriptional induction of the genes that encode the β2-integrin family of adhesion molecules. This induction likely maintains the long-term inflammation by which hypoxia drives the pathogenesis of CKD. Consequently, targeting these transcriptional mechanisms would appear to represent a promising new therapeutic strategy.

Impact of Obstructive Sleep Apnea Syndrome on Endothelial Function, Arterial Stiffening, and Serum Inflammatory Markers: An Updated Meta-analysis and Metaregression of 18 Studies

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) has been indicated to contribute to the development of cardiovascular disease; however, the underlying mechanism remains unclear. This study aimed to test the hypothesis that OSAS may be associated with cardiovascular disease by elevating serum levels of inflammatory markers and causing arterial stiffening and endothelial dysfunction.

METHODS AND RESULTS

Related scientific reports published from January 1, 2006, to June 30, 2015, were searched in the following electronic literature databases: PubMed, Excerpta Medica Database, ISI Web of Science, Directory of Open Access Journals, and the Cochrane Library. The association of OSAS with serum levels of inflammatory markers, endothelial dysfunction, and arterial stiffening were investigated. Overall, 18 eligible articles containing 736 patients with OSAS and 424 healthy persons were included in this meta-analysis. Flow-mediated dilation in patients with moderate-severe OSAS was significantly lower than that in controls (standardized mean difference -1.02, 95% CI -1.31 to -0.73, P<0.0001). Carotid-femoral pulse wave velocity (standardized mean difference 0.45, 95% CI 0.21-0.69, P<0.0001), augmentation index (standardized mean difference 0.57, 95% CI 0.25-0.90, P<0.0001), and serum levels of high-sensitivity C-reactive protein and C-reactive protein (standardized mean difference 0.58, 95% CI 0.42-0.73, P<0.0001) were significantly higher in patients with OSAS than in controls.

CONCLUSION

OSAS, particularly moderate-severe OSAS, appeared to reduce endothelial function, increase arterial stiffness, and cause chronic inflammation, leading to the development of cardiovascular disease.

Effects of continuous positive airway pressure treatment on coronary vasoreactivity measured by (82)Rb cardiac PET/CT in obstructive sleep apnea patients

PURPOSE

Obstructive sleep apnea syndrome (OSA) increases the risk of cardiovascular disease. We aimed at evaluating the effect of continuous positive airway pressure (CPAP) treatment on coronary endothelium-dependent vasoreactivity in OSA patients by quantifying myocardial blood flow (MBF) response to cold pressure testing (CPT).

METHODS

In the morning after polysomnography (PSG), all participants underwent a dynamic (82)Rb cardiac positron emitting tomography/computed tomography (PET/CT) scan at rest, during CPT and adenosine stress. PSG and PET/CT were repeated at least 6 weeks after initiating CPAP treatment. OSA patients were compared to controls and according to response to CPAP. Patients' characteristics and PSG parameters were used to determine predictors of CPT-MBF.

RESULTS

Thirty-two untreated OSA patients (age 58 ± 13 years, 27 men) and 9 controls (age 62 ± 5 years, 4 men) were enrolled. At baseline, compared to controls (apnea-hypopnea index (AHI) = 5.3 ± 2.6/h), untreated OSA patients (AHI = 48.6 ± 19.7/h) tend to have a lower CPT-MBF (1.1 ± 0.2 mL/min/g vs. 1.3 ± 0.4 mL/min/g, p = 0.09). After initiating CPAP, CPT-MBF was not different between well-treated patients (AHI <10/h) and controls (1.3 ± 0.3 mL/min/g vs. 1.3 ± 0.4 mL/min/g, p = 0.83), but it was lower for insufficiently treated patients (AHI ≥10/h) (0.9 ± 0.2 mL/min/g vs. 1.3 ± 0.4 mL/min/g, p = 0.0045). CPT-MBF was also higher in well-treated than in insufficiently treated patients (1.3 ± 0.3 mL/min/g vs. 0.9 ± 0.2 mL/min/g, p = 0.001). Mean nocturnal oxygen saturation (β = -0.55, p = 0.02) and BMI (β = -0.58, p = 0.02) were independent predictors of CPT-MBF in OSA patients.

CONCLUSIONS

Coronary endothelial vasoreactivity is impaired in insufficiently treated OSA patients compared to well-treated patients and controls, confirming the need for CPAP optimization.

Hematological Parameters as Predictors of Cardiovascular Disease in Obstructive Sleep Apnea Syndrome Patients

We investigated the role of the red cell distribution width (RDW) and other parameters including platelet (PLT) count, mean platelet volume (MPV), and platelet distribution width (PDW) in patients with obstructive sleep apnea syndrome (OSAS) having cardiovascular diseases (CVDs). Patients (n = 142) having sleep disorders and who applied for a night polysomnography were included in this study. For statistical analysis, chi-square test, bivarite correlation, and logistic and stepwise regression tests were used. A positive correlation between RDW MPV, RDW, and body mass index as well as PLT and apnea-hypopnea index were observed. A negative correlation between AHI and PDW (P= .041) and a positive correlation between AHI and PLT (P= .010) were found in the patients ≥40 years old with CVD. The RDW was higher in patients ≥40 years old who had CVD (P= .016), and 19% of them had RDW >14%. The PDW (odds ratio = 6.02 [95% confidence interval = 1.3-28.2],P= .023) appeared to be associated with increased risk of hyperlipidemia in patients with severe OSAS. If these results are confirmed, RDW could be used with other markers, especially PLT and PDW, in prediction of CVD in patients with severe OSAS.

Delayed neutrophil apoptosis mediates intermittent hypoxia-induced progressive heart failure in pressure-overloaded rats

BACKGROUND AND OBJECTIVE

Obstructive sleep apnea (OSA) and heart failure (HF) are common coexisting diseases. Intermittent hypoxia (IH), caused by repeated apnea/hypopnea events, accompanied by increased systemic inflammation, might contribute to the promotion of HF.

METHODS

To assess the hypothesis, rats were exposed to IH or normal air condition 4 weeks on the basis of normal heart function or pre-existing HF, which was induced by pressure overload caused by abdominal aortic constriction surgery performed 12 weeks earlier. Echocardiography was performed before and after IH exposure to evaluate left ventricular (LV) function. Serum concentrations of pro-inflammatory cytokines TNF-α and IL-6 were detected by enzyme-linked immunosorbent assay. Flow cytometric analysis was used to determine the apoptotic rate of polymorphonuclear neutrophils (PMNs).

RESULTS

The echocardiographic study showed a significant decrease in LV fractional shortening (FS) and ejection fraction (EF) as well as an increase in the LV relative wall thickness (RWT) index in HF rats, which was aggravated by further exposure to IH compared with single-handed HF-only and sham-IH and sham-control groups. A reduced PMN apoptotic rate was observed in HF-IH rats compared with HF-only, sham-IH, and sham-control rats. Serum concentrations of TNF-α and IL-6 were also increased in HF-IH rats, accompanied by delayed PMN apoptosis, indicating significant systemic inflammation induced by IH.

CONCLUSION

The results of this study demonstrated that IH aggravates LV remodeling and heart dysfunction in rats with pre-existing HF. Delayed neutrophil apoptosis, which was revealed in HF rats following exposure to IH, contributed to the exacerbation of myocardial damage and progression of heart dysfunction.

High prevalence of peripheral arterial disease in patients with obstructive sleep apnoea

INTRODUCTION

Obstructive sleep apnoea (OSA) merits increasing attention as cardiovascular risk factor. Whereas carotid and coronary artery disease have been associated with OSA, occurrence of peripheral arterial disease (PAD) in OSA remains undefined.

METHODS

We screened 100 patients with suspected OSA for PAD. After polysomnography, each patient underwent standardized angiological testing including ankle-brachial index (ABI), central pulse wave velocity, pulse wave index and duplex sonography.

RESULTS

Among total study population, PAD prevalence accounted for 88%, of those 68% had asymptomatic plaques and 20% were symptomatic Fontaine ≥ IIa. In confirmed OSA, prevalence raised up to 98%. Except for smoking habits, distribution of established risk factors did not differ between OSA groups (patients without, mild, intermediate and severe OSA). Presence of plaque, Fontaine PAD stages and intermittent claudication exhibited significant gain with increasing AHI. A logistic regression model revealed that age (OR = 1.199, 95% CI [1.066; 1.348]) and the logarithmically transformed AHI (OR = 5.426, 95% CI [1.068; 27.567]) had the strongest influence on plaque presence. Central pulse wave velocity as marker of arterial stiffness was positively correlated with AHI.

CONCLUSION

OSA is associated with a high prevalence of PAD. This implies substantial diseasés under-recognition and a presumable atherogenic role of OSA in the pathogenesis of PAD. However, vasoprotective impact of OSA treatment remains to be determined.

Biomarkers associated with obstructive sleep apnea and morbidities: a scoping review

OBJECTIVE

To map potential biomarkers of obstructive sleep apnea (OSA)-associated morbidities in both adults and children, to identify gaps in current evidence, and to determine the value of conducting a full systematic review.

METHODS

A scoping review was undertaken of studies in patients with OSA that evaluated the potential value of biological markers in identifying OSA-associated morbidities. Retained articles were only those studies whose main objective was to identify morbidity biomarkers in subjects with OSA, the latter being confirmed with a full overnight polysomnography (PSG) in a laboratory or at-home settings. The methodology of the selected studies was classified using an adaptation of the evidence quality criteria recommended by the American Academy of Pediatrics. Additionally the biomarkers were categorized according to their potential clinical applicability.

RESULTS

572 citations were identified of which 48 met inclusion criteria. Thirty-four studies were conducted in adults and 14 involved children. Most of the studies evaluated blood biomarkers, and presented 31 potential diagnostic biomarkers.

CONCLUSION

The majority of studies that performed explored blood-based biomarkers, with most not identifying definitive morbidity biomarkers. Of the potentially promising morbidity biomarkers, plasma IL-6 and high sensitivity C-reactive protein appear to exhibit a favorable profile, and may discriminate OSA patients with and without morbidities in both adults and children. MRP 8/14 was retained in children as well as cardiovascular morbidity-associated biomarker. Urinary neurotransmitters may also provide a good tool for screening OSA cognitive morbidity in children.

Angiotensin-converting enzyme inhibitor captopril reverses the adverse cardiovascular effects of polymerized hemoglobin

AIM

Cell-free hemoglobin-based oxygen carriers (HBOCs) may increase the risk of myocardial infarction and death. We studied the effect of an angiotensin-converting enzyme (ACE) inhibitor on HBOC-induced adverse cardiovascular outcomes and elucidated the underlying mechanisms.

RESULTS

With a dog cardiopulmonary bypass model, we demonstrated that a high-dose HBOC (3%, w/v) did not reduce-but aggravated-cardiac ischemia/reperfusion injury. Animals administered a high-dose HBOC experienced coronary artery constriction and depression of cardiac function. Exposure of isolated coronary arteries or human umbilical vein endothelial cells to high-dose HBOC caused impaired endothelium-dependent relaxation, increased endothelial cell necrosis/apoptosis, and elevated NAD(P)H oxidase expression (gp91(phox), p47(phox), p67(phox), and Nox1) and reactive oxygen species (ROS) production. All observed adverse outcomes could be suppressed by the ACE inhibitor captopril (100 μM). Co-incubation with free radical scavenger tempol or NAD(P)H oxidase inhibitor apocynin had no effect on captopril action, suggesting that the positive effects of captopril are ROS- and NAD(P)H oxidase dependent. ACE inhibition by captopril also contributed to these effects. In addition, bioavailable nitrite oxide (NO) reduced by high-dose HBOC was preserved by captopril. Furthermore, HBOC, at concentrations greater than 0.5%, inhibited large conductance Ca(2+)-activated K(+) channel currents in vascular smooth muscle cells in a dose-dependent manner, although captopril failed to improve current activity, providing additional evidence that captopril's effects are mediated by the endothelium, but not by the smooth muscle.

INNOVATION AND CONCLUSION

Captopril alleviates high-dose HBOC-induced endothelial dysfunction and myocardial toxicity, which is mediated by synergistic depression of NAD(P)H oxidase subunit overproduction and increases in vascular NO bioavailability.

Obstructive sleep apnoea increases the incidence of morning peak of onset in acute myocardial infarction

AIMS

There exists a discrepancy regarding the relationship between obstructive sleep apnoea (OSA) and circadian variation during the onset of acute myocardial infarction (MI). We hypothesized that OSA patients show a characteristic circadian variation and that the severity of OSA significantly affects this variation.

METHODS AND RESULTS

The present study included 288 patients with first acute MI who underwent percutaneous coronary intervention within 12 h of symptom onset. The diagnosis of OSA required an apnoea-hypopnoea index (AHI) of ≥5 events/h. A total of 216 patients fulfilled the OSA criteria. The incidence of MI onset between 06:00 and 11:59 hours was significantly higher in OSA patients than in control patients (38 vs. 25%, p=0.039). Circadian variation in the morning peak of MI onset was attenuated in mild OSA (as defined by AHI, 5.0-14.9 events/h; 33 vs. 25%, p=0.240). Moderate-to-severe OSA (as defined by AHI ≥15.0 events/h) clearly increased the incidence of MI onset between 06:00 and 11:59 hours (43 vs. 25%, p=0.014). Multiple logistic regression adjusting for AHI (≥15.0 events/h), age, body mass index, hypertension, and current smoking showed that moderate-to-severe OSA significantly contributed to MI onset between 06:00 and 11:59 hours (odds ratio 2.00, p=0.010).

CONCLUSIONS

OSA showed a morning peak with regard to MI onset, and moderate-to-severe OSA significantly enhanced this circadian variation.

Effects of moderate-to-severe obstructive sleep apnea on the clinical manifestations of plaque vulnerability and the progression of coronary atherosclerosis in patients with acute coronary syndrome

AIMS

It is unclear whether obstructive sleep apnea (OSA) increases the recurrence of acute coronary syndrome (ACS) in patients with acute myocardial infarction (MI). We hypothesized that moderate-to-severe OSA increased the number of adverse cardiovascular events in patients who underwent primary percutaneous coronary intervention (PCI).

METHODS AND RESULTS

This study included 272 patients with acute MI. Polysomnography at first admission determined that 124 patients suffered from moderate-to-severe OSA. The main study outcome measures were cardiac death, recurrence of ACS, and re-admission for heart failure. Major adverse cardiac events (MACEs) were defined as composite end points of individual clinical outcomes. Follow-up coronary angiograms were obtained in 222 patients. PCI-related measures were target vessel revascularization and newly necessitated PCI for progressive lesions. The moderate-to-severe OSA patients had increased ACS recurrence and MACEs compared with patients with mild OSA or without sleep apnea (16% vs. 7%, p = 0.014; 22% vs. 11%, p = 0.014, respectively). PCI for progressive lesions was also higher in the moderate-to-severe OSA patients (28% vs. 15%, p = 0.015). Cox regression analysis showed that moderate-to-severe OSA was an independent predictor of ACS recurrence (hazard ratio = 2.30, p = 0.040). In addition, moderate-to-severe OSA was an independent predictor of PCI for progressive lesions, with a hazard ratio of 2.38 (p = 0.015).

CONCLUSIONS

Moderate-to-severe OSA increased the risk of ACS and the incidence of PCI for progressive lesions. Increased plaque vulnerability might be related to these clinical manifestations.

The importance of laboratory parameters in patients with obstructive sleep apnea syndrome

Platelet activation and inflammation are the related mechanisms of pathogenesis in obstructive sleep apnea syndrome (OSAS). Mean platelet volume (MPV) and platelet distribution width (PDW) are the markers of platelet activation. C-reactive protein (CRP) and red cell distribution width (RDW) in relation to the inflammation in OSAS might be increased. We aimed to investigate the correlation of the MPV, PDW, and RDW levels with the severity of OSAS. We included 98 patients with suspected OSAS, evaluated by polysomnography. According to their apnea-hypopnea index (AHI), patients were divided into group A (n = 20; 20.4%) with AHI below 5/h; group B (n = 15; 15.3%) with AHI 5-14.9/h; group C (n = 26; 26.5%) with AHI 15-29.9/h; and group D (n = 37; 37.8%) with AHI ≥30/h. Hemoglobin, MPV, PDW, and RDW were measured using an automated blood cell counter. BMI and age showed a statistically significant and gradual increase in AHI groups. Hemoglobin, platelet, CRP, MPV, and RDW values did not differ between AHI groups. PDW was significantly higher in group D (mean value 14.4 ± 1.8) than in group A (13.2 ± 0.5) (P < 0.001). Epworth sleepiness scale was significantly higher in group D (9.9 ± 5.5) than in group A (5.6 ± 3.5), B (9.2 ± 3.6) and C (6.6 ± 3.8) (P = 0.005). When the four groups were compared, group D had the lowest minimum SpO2 value [group A (89.4 ± 3.0), B (86.7 ± 4.2), C (81.2 ± 6.4), and D (68.2 ± 13.0)]. There was a statistically significant correlation between AHI and age (r = 0.35, P < 0.001), BMI (r = 0.31, P = 0.003), PDW (r = 0.28, P = 0.006), and Epworth sleepiness scale (r = 0.29, P = 0.007). However, AHI was not correlated with CRP, MPV, and RDW. PDW is higher in severe OSAS and is correlated with different parameters of breathing function during sleep. The severity of OSAS was not correlated with CRP, MPV, and RDW. These findings show an evidence for platelet activation in OSAS and suggest that PDW might be related markers of OSAS severity.

Serum omentin levels in patients with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is associated with increased rates of cardiovascular diseases (CVD). The basic mechanisms involved in the increased cardiovascular risk of OSAS remain unclear. Recent discoveries of fat-secreted substances which serve endocrine roles improve our understanding of the relationship between OSAS, CVD, and the metabolic syndrome. In this study, we aimed to examine associations between omentin levels and OSA.

METHODS

Forty-six newly diagnosed OSA patients and 35 non-apneic controls were enrolled in this study. Demographical data, cigarette smoking status, previous history of chronic diseases including CVD and metabolic diseases and drugs, and habits were obtained using a standardized questionnaire. All patients underwent polysomnographic evaluation. Omentin was measured the following morning.

RESULTS

The mean age was 48.1 ± 12.5 (24-74) years in the OSA group and 42.8 ± 14.1 (21-69) years in the control group. Of the 81 patients, 46 (34 males and 12 females) were classified as having OSA and 35 patients (20 males and 15 females) as control. Plasma levels of omentin were found to be markedly higher in OSA patients (570.8 ng/ml) than in the control group (432.0 ng/ml; p < 0.001). In addition, plasma levels of omentin were found to be high in all OSA subgroups than in controls. The plasma omentin levels were significantly correlated only with age in patients with OSA.

CONCLUSIONS

We conclude that circulating omentin levels are elevated in OSA patients. To the best of our knowledge, this is the first clinical study that demonstrated the association between omentin and OSA.

Obstructive sleep apnea syndrome, vascular pathology, endothelial function and endothelial cells and circulating microparticles

Accelerated atherosclerosis and increased cardiovascular risk are frequently reported in patients with obstructive sleep apnea (OSA) syndrome. In this article the authors attempt a review of the current understanding of the relationship between vascular risk and OSA syndrome based on large cohort studies that related the disease to several cardiovascular risk factors and vascular pathologies. We also discuss the pathophysiological mechanisms that may be involved in this relationship, starting with endothelial dysfunction and its mediators. These include an increased oxidative stress and inflammation as well as several disorders of coagulation and lipid metabolism. Moreover, circulating microparticles from activated leukocytes (CD62L_MPs) are higher in patients with OSA and there is a positive correlation between circulating levels of CD62L_MPs and nocturnal hypoxemia severity. Finally, circulating level of endothelial microparticles and circulating endothelial cells seem to be increased in patients with OSA. Also, endothelial progenitor cells are reduced and plasma levels of the vascular endothelial growth factor are increased.

Significance of endothelial dysfunction in sleep-related breathing disorder

The endothelium functions not only as a semi-selective barrier between body tissue and circulation; it also plays an active role in the maintenance of a healthy vasculature. Endothelial dysfunction is increasingly found to play a pivotal role in the pathogenesis of atherosclerosis. Impaired endothelium-dependent vasodilation, as a marker of endothelial dysfunction, predates and predicts cardiovascular disease. Endothelial dysfunction is thought to result from oxidative stress, inflammatory gene activation and cytokine cascade, as well as impairment of endothelial repair mechanisms. In the context of sleep-related breathing disorders, obstructive sleep apnoea (OSA) is postulated to contribute independently to cardiovascular morbidity and mortality. Thus, endothelial dysfunction is an important target of research in vascular pathogenesis and also serves as an intermediary outcome indicator in clinical trials evaluating cardiovascular sequelae in OSA. Basic or translational studies have identified cellular and molecular mechanisms of potential relevance to endothelial dysfunction in OSA, while epidemiological or clinical studies have shown endothelial dysfunction attributable to sleep-disordered breathing, which could improve with effective treatment of OSA. Endothelial dysfunction is poised to serve as a call for timely intervention with possibility of halting or even reverting vascular injury in sleep-related breathing disorders. Much remains to be explored about the complex pathways of endothelial dysfunction and its clinical manifestations in subjects with OSA, which are likely to involve multiple contributing factors. Evidence-based information will allow us to construct the framework for guiding individualized clinical management and public health strategies for OSA, as well as cardiometabolic diseases.

Serum cardiotrophin-1 and IL-6 levels in patients with obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is associated with increased rates of cardiovascular diseases (CVD). Basic mechanisms involved in the increased cardiovascular risk of OSAS remain unclear. Inflammation has been shown to potentially play a critical role in this association. The aim of the present study was to investigate the level of cardiotrophin-1 (CT-1) in patients with OSAS. Forty-eight newly diagnosed OSAS patients and 37 nonapneic controls were enrolled in this study. Demographic data, cigarette smoking status, previous history of chronic diseases including CVD and metabolic diseases and drugs, and habits were obtained by a standardized questionnaire. All patients underwent polysomnographic evaluation. The mean age was 48.3 ± 12.3 (24-74) years in OSAS group. Median apnea-hypopnea index was 23.6 (6-91.8) and median body mass index was 30.4 (24.2-49.4) in the OSAS group. Plasma CT-1 levels in OSAS and control groups, respectively, were 12.03 ± 1.08 and 11.85 ± 1.18 pg/ml. There was no significant difference in the plasma levels of CT-1 and IL-6 between the OSAS group and the controls.

Effects of continuous positive airway pressure on endothelial function and circulating progenitor cells in obstructive sleep apnoea: a randomised sham-controlled study

OBJECTIVE

Obstructive sleep apnoea (OSA) is characterised by reoccurring apnoeas and hypopneas, causing repetitive hypoxia and reoxygenation, and is associated with endothelial dysfunction and reduced levels of circulating progenitor cells (CPCs). The potential to improve endothelial function and CPC levels in people with OSA by preventing hypoxic episodes with Continuous Positive Airway Pressure (CPAP) was investigated in a sham-controlled CPAP study.

METHODS

Men with moderate-to-severe OSA (mean ± SD: age=49 ± 12 y, apnoea hypopnea index (AHI)=37.6 ± 16.4 events/h, body mass index=31.5 ± 5.7 kg/m(2)) who were CPAP naïve without diabetes mellitus were randomised in a 12-week double-blind sham-controlled parallel group study to receive either active (n=25) or sham (n=21) CPAP. CPCs, isolated from blood, were measured by flow cytometry and by co-staining cultured cells (7 days) with acetylated low-density lipoprotein (acLDL) and lectin. Endothelial function was assessed by peripheral arterial tonometry (PAT).

RESULTS

Compared to sham, CPAP significantly decreased AHI (mean between-group difference -36.0 events/h; 95%CI, -49.7 to -22.3, p<0.0001) after 12 weeks. Despite this improvement in AHI, CPAP had no effect on change in CPC levels (including CD34(+)/KDR(+) (565 cells/mL; -977 to 2106, p=0.45), CD34(+)/KDR(+)/CD45(-) (37.0 cells/mL; -17.7 to 85.7, p=0.13), acLDL(+)/lectin(+) (-43.1 cells/field, -247 to 161, p=0.67)) or change in endothelial function (0.27; -0.14 to 0.67, p=0.19) compared to sham therapy.

CONCLUSIONS

Despite the improvement in OSA parameters and ablation of apnoeic events by CPAP, CPC counts and endothelial function in men with moderate-to-severe OSA were not significantly improved after 12 weeks of therapeutic CPAP when compared to sham control.

Circulating endothelial and progenitor cells: Evidence from acute and long-term exercise effects

Circulating bone-marrow-derived cells, named endothelial progenitor cells (EPCs), are capable of maintaining, generating, and replacing terminally differentiated cells within their own specific tissue as a consequence of physiological cell turnover or tissue damage due to injury. Endothelium maintenance and restoration of normal endothelial cell function is guaranteed by a complex physiological procedure in which EPCs play a significant role. Decreased number of peripheral blood EPCs has been associated with endothelial dysfunction and high cardiovascular risk. In this review, we initially report current knowledge with regard to the role of EPCs in healthy subjects and the clinical value of EPCs in different disease populations such as arterial hypertension, obstructive sleep-apnea syndrome, obesity, diabetes mellitus, peripheral arterial disease, coronary artery disease, pulmonary hypertension, and heart failure. Recent studies have introduced the novel concept that physical activity, either performed as a single exercise session or performed as part of an exercise training program, results in a significant increase of circulating EPCs. In the second part of this review we provide preliminary evidence from recent studies investigating the effects of acute and long-term exercise in healthy subjects and athletes as well as in disease populations.

Sleep-Disordered Breathing in Acute Ischemic Stroke and Transient Ischemic Attack: Effects on Short- and Long-Term Outcome and Efficacy of Treatment with Continuous Positive Airways Pressure – Rationale and Design of the SAS Care Study

Objectives

Sleep-disordered breathing represents a risk factor for cardiovascular morbidity and mortality and negatively affects short-term and long-term outcome after an ischemic stroke or transient ischemic attack. The effect of continuous positive airways pressure in patients with sleep-disordered breathing and acute cerebrovascular event is poorly known. The SAS CARE 1 study assesses the effects of sleep-disordered breathing on clinical evolution, vascular functions, and markers within the first three-months after an acute cerebrovascular event. The SAS CARE 2 assesses the effect of continuous positive airways pressure on clinical evolution, cardiovascular events, and mortality as well as vascular functions and markers at 12 and 24 months after acute cerebrovascular event.

Methods

SAS CARE 1 is an open, observational multicenter study in patients with acute cerebrovascular event acutely admitted in a stroke unit: a sample of 200 acute cerebrovascular event patients will be included. Vascular functions and markers (blood pressure, heart rate variability, endothelial function by peripheral arterial tonometry and specific humoral factors) will be assessed in the acute phase and at three-months follow-up. SAS CARE 2 will include a sample of patients with acute cerebrovascular event in the previous 60–90 days. After baseline assessments, the patients will be classified according to their apnea hypopnea index in four arms: non-sleep-disordered breathing patients (apnea hypopnea index <10), patients with central sleep-disordered breathing, sleepy patients with obstructive apnea hypopnea index ≥20, which will receive continuous positive airways pressure treatment, nonsleepy patients with obstructive sleep-disordered breathing (apnea hypopnea index ≥20), which will be randomized to receive continuous positive airways pressure treatment or not.

Conclusions

The SAS CARE study will improve our understanding of the clinical sleep-disordered breathing in patients with acute cerebrovascular event and the feasibility/efficacy of continuous positive airways pressure treatment in selected patients with acute cerebrovascular event and sleep-disordered breathing.

Effect of Han-uvulopalatopharyngoplasty on flow-mediated dilatation in patients with moderate or severe obstructive sleep apnea syndrome

CONCLUSION

Flow-mediated dilatation (FMD) is decreased in patients with moderate or severe obstructive sleep apnea syndrome (OSAS), and Han-uvulopalatopharyngoplasty (H-UPPP) can improve FMD.

OBJECTIVE

To evaluate FMD in patients with moderate or severe OSAS and observe the effect of H-UPPP on FMD in these patients.

METHODS

Forty-nine patients who were first diagnosed with moderate or severe OSAS by polysomnography (PSG) and had no other diseases served as the experimental group, and 35 individuals with normal PSG as the control group. FMD was measured with high-resolution B-mode ultrasonography in the two groups. PSG and FMD were again performed in the experimental group 6 months after H-UPPP.

RESULTS

FMD was significantly lower in the experimental group than in the control group (6.5 ± 2.1% vs 11.2 ± 2.9%, p < 0.01). FMD was significantly improved 6 months after H-UPPP compared with preoperative FMD (9.7 ± 2.7% vs 6.5 ± 2.1%, p < 0.01).

Effects of continuous positive airway pressure (CPAP) treatment for obstructive sleep apnea in arterial stiffness: a meta-analysis

Obstructive sleep apnea (OSA) is associated with increased arterial stiffness, a cumulative indicator of arterial health. Continuous positive airway pressure (CPAP) is the gold standard treatment for OSA. We conducted a meta-analysis of the available literature investigating the effect of CPAP on arterial stiffness in patients with OSA. Fifteen articles (n = 615 patients) assessing indices of arterial stiffness were identified. Five different meta-analyses were performed assessing: a) all indices of arterial stiffness, b) augmentation index (AIx), c) all pulse wave velocities (PWV), d) brachial-ankle PWV and e) carotid-femoral PWV. Pooled standardized mean differences (SMDs) and weighted mean differences (WMDs) were appropriately calculated through fixed or random effects models after assessing between-study heterogeneity. A significant improvement of all indices of arterial stiffness was observed after CPAP treatment (SMD = -0.74; 95%CI: -1.08 to -0.41). AIx and PWVs were also significantly improved (WMD = -4.86; 95%CI: -7.31 to -2.41 and WMD = -0.87; 95%CI: -0.98 to -0.77, respectively), as well as brachial-ankle PWV and carotid-femoral PWV (WMD = -0.86; 95%CI: -0.97 to -0.75 and WMD = -1.21; 95%CI:-1.92 to -0.50, respectively). Neither the proportion of compliant patients nor the duration of CPAP use altered the effect of arterial stiffness reduction after CPAP treatment. In conclusion, our meta-analyses showed significant improvements in all indices of arterial stiffness after CPAP treatment in patients with OSA. As clinical use of arterial stiffness is growing in popularity, the efficacy of this useful tool in assessing cardiovascular risk reduction among patients with OSA treated with CPAP needs to be further explored.

Heterogeneity in apoptotic responses of microvascular endothelial cells to oxidative stress

Oxidative stress contributes to disease and can alter endothelial cell (EC) function. EC from different vascular beds are heterogeneous in structure and function, thus we assessed the apoptotic responses of EC from lung and heart to oxidative stress. Since protein kinase Cδ (PKCδ) is activated by oxidative stress and is an important modulator of apoptosis, experiments assessed the level of apoptosis in fixed lung and heart sections of PKCδ wild-type (PKCδ(+/+)) and null (PKCδ(-/-)) mice housed under normoxia (21% O(2)) or hyperoxia (~95% O(2)). We noted a significantly greater number of TUNEL-positive cells in lungs of hyperoxic PKCδ(+/+) mice, compared to matched hearts or normoxic organs. We found that 33% of apoptotic cells identified in hyperoxic lungs of PKCδ(+/+) mice were EC, compared to 7% EC in hyperoxic hearts. We further noted that EC apoptosis was significantly reduced in lungs of PKCδ(-/-) hyperoxic mice, compared to lungs of PKCδ(+/+) hyperoxic mice. In vitro, both hyperoxia and H(2)O(2) promoted apoptosis in EC isolated from microvasculature of lung (LMVEC), but not from the heart (HMVEC). H(2)O(2) treatment significantly increased p38 activity in LMVEC, but not in HMVEC. Inhibition of p38 attenuated H(2)O(2)-induced LMVEC apoptosis. Baseline expression of total PKCδ protein, as well as the caspase-mediated, catalytically active PKCδ cleavage fragment, was higher in LMVEC, compared to HMVEC. PKCδ inhibition significantly attenuated H(2)O(2)-induced LMVEC p38 activation. Conversely, overexpression of wild-type PKCδ or the catalytically active PKCδ cleavage product greatly increased H(2)O(2)-induced HMVEC caspase and p38 activation. We propose that enhanced susceptibility of lung EC to oxidant-induced apoptosis is due to increased PKCδ→p38 signaling, and we describe a PKCδ-centric pathway which dictates the differential response of EC from distinct vascular beds to oxidative stress.

Importance and management of chronic sleep apnoea in cardiology

Sleep apnoea is a common, yet underestimated, chronic disorder with a major impact on morbidity and mortality in the general population. It is quickly becoming recognized as an independent risk factor for cardiovascular impairment. Hypertension, coronary artery disease, diabetes, cardiovascular rhythm and conduction abnormalities, cerebrovascular disease, and heart failure have all been linked to this syndrome. This review will explore the critical connection between sleep apnoea and chronic cardiovascular diseases while highlighting established and emerging diagnostic and treatment strategies.