Endothelial dysfunction and C-reactive protein in relation with the severity of obstructive sleep apnea syndrome

Breast cancer cells and adipocytes in hypoxia: metabolism regulation

Adipocytes play a significant role in breast cancer due to the unique histological structure of the breast. These have not only been detected adjacent to breast cancer cells but they have also been implicated in cancer development. Adipocytes in obese individuals and tumor microenvironment (TME) have a common feature, that is, hypoxia. The increased expression of hypoxia-inducible factor (HIF)-1α is known to alter the metabolism and functions of adipocytes. In this study, we described the mechanism linking the hypoxia-sensing pathway manifested by HIF to adipocytes and breast cancer and discussed the mechanism underlying the role of hypoxic adipocytes in breast cancer development from the perspective of metabolic remodeling. The processes and pathways in hypoxic adipocytes could be a promising target in breast cancer therapy.

The causal relationships between obstructive sleep apnea and elevated CRP and TNF-α protein levels

BACKGROUND

Obstructive sleep apnea (OSA) and inflammation are closely related. This study aimed to evaluate the associations and causal effect between C-reactive protein (CRP) and tumour necrosis factor-alpha (TNF-α) levels andOSA.

METHODS

Pooled analysis was conducted to compare the expression differences of CRP and TNF-α between OSA patients with different severity and controls, and between continuous positive airway pressure (CPAP) and non-CPAP interventions for OSA patients. Using published GWAS summary statistics, we conducted a bidirectional two-sample Mendelian Randomization (MR) to estimate the causal relationships between CRP and TNF-α levels and OSA risk. Effect estimates were evaluated using inverse-variance weighted (IVW) as primary method, and several other MR methods as sensitivity analysis.

RESULTS

Both TNF-α (WMD [95%CI] = 5.86 [4.80-6.93] pg/ml, p < .00001) and CRP (WMD [95%CI] = 2.66 [2.15-3.17] mg/L, p < .00001), showed a significant increase in OSA patients compared with controls and this increasing trend was associated with OSA severity. Besides, compared to blank control (non-CPAP), CPAP treatment can reduce high TNF-α (WMD [95%CI]= -4.44 [-4.81, -4.07]pg/ml, p < .00001) and CRP (WMD [95%CI]= -0.91 [-1.65, -0.17] mg/l, p = .02) in OSA. Moreover, the primary MR analysis by IVW showed that OSA was the genetically predicted cause of elevated CRP (estimate: 0.095; 95% CI, [0.010-0.179]; p = .029) using six SNPs as the instrument variable, which were repeated by weighted median (estimate: 0.053; 95% CI, [0.007, 0.100]; p =.024) and MR RAPS (estimate: 0.109; 95% CI, [0.079, 0.140]; p = 1.98x10^-12). Besides, the causal effect from elevated CRP on increased OSA risk was almost significant by IVW (OR:1.053; 95% CI, [1.000, 1.111]; p = .053). However, there were no causal associations between TNF-α and OSA from both directions.

CONCLUSIONS

Increased CRP and TNF-α were associated with OSA severity and sensible to CPAP treatment. Also, OSA had a suggestive causal effect on elevated CRP.

A Case-Control Study on the Changes in High-Sensitivity C-Reactive Protein and Tumor Necrosis Factor-Alpha Levels with Surgical Treatment of OSAS

Obstructive sleep apnea syndrome (OSAS) is a common but underdiagnosed condition with significant health and economic implications for society. Inflammatory mediators are proposed to be associated with the presence and severity of OSAS and contribute to morbidity and mortality. This paper details a prospective non-randomized case control study of a cohort of subjects, who underwent surgical treatment of OSAS and were enrolled to assess the sleep parameters and blood levels of selected inflammatory markers at pre-operative and post-operative time points, also comparing them to the levels in a control group. A total of 25 study subjects and 18 control subjects were enrolled. Median values and interquartile range (IQR) of the apnea-hypopnea index (AHI) in the study group pre-operatively and post-operatively were 34 (18.5-45.5) and 13.3 (7.5-27.3), while in the control group 1.4 (1.0-2.1) per hour. The mean (IQR) hs-CRP levels (mg/L) were 1.782 (0.941-5.594) and 1.980 (0.990-5.445) in the study group, pre-operatively and post-operatively, respectively, while 0.891 (0.767-1.436) in the control group. The mean (IQR) TNF-α levels (pg/mL) were 7.999 (6.137-9.216) and 6.614 (5.534-7.460) pre-and post-operatively, respectively, and were 6.000 (5.026-6.823) in the control group. Results demonstrated that both inflammatory markers, hs-CRP and TNF-α, are higher in subjects with OSAS compared to the controls, and their levels decrease, but are still higher than the controls, after successful surgical treatment. Further analysis including the body mass index and age demonstrated that these changes were significant for TNF-α, but not hs-CRP.

Biochemical Markers and Obstructive Sleep Apnea Risk in Individuals After Long-Term Bariatric Surgery

BACKGROUND

Individuals who have undergone long-term bariatric surgery may be at increased obstructive sleep apnea (OSA) risk. The purpose of this study was to estimate the frequency of OSA risk and its associations, via biochemical markers, in patients who have undergone long-term bariatric surgery.

METHODS

This cross-sectional study evaluated patients after 5 years or more post Roux-en-Y gastric bypass. Biochemical markers, anthropometrics, and OSA risk, via the STOP-Bang score screening tool, were evaluated. Independent Student t, Pearson's chi-squared, or correlation tests were applied, according to total OSA risk score groups or its isolated components.

RESULTS

Among the 77 patients evaluated (88.3% female; body mass index = 32.7 ± 5.8 kg/ m²; postoperative time = 9.9 ± 3.1 years), 36 were at risk for OSA. OSA risk score was positively correlated to high-sensitivity C-reactive protein levels (r² = 0.270; p = 0.025), triglycerides (r² = 0.338, p = 0.004), total cholesterol (r² = 0,262; p = 0,028), and HbA1c (r² = 0.332; p = 0.005). Compared to each counterpart, basal insulin and triglycerides were higher among those who self-reported witnessed apnea (12.8 ± 6.5 vs 8.1 ± 3.8, p = 0.013; 136.4 ± 41.1 vs 88.5 ± 34.8, p = 0.001, respectively), while levels of total cholesterol and LDL-C were higher in participants who reported tiredness (183.9 ± 27.0 vs 164.8 ± 33.4, p = 0.005; 105.9 ± 24.4 vs 92.0 ± 26.6, p = 0.018). Participants with snoring also had higher levels of triglycerides (107 ± 41.1 vs 83.7 ± 33.9, p = 0.010).

CONCLUSIONS

OSA risk was highly prevalent among patients who had undergone long-term bariatric surgery, as noted via increased STOP-Bang scores, as were isolated components related to inflammatory markers and lipid and glycemic profile.

Evaluation of Blood Levels of C-Reactive Protein Marker in Obstructive Sleep Apnea: A Systematic Review, Meta-Analysis and Meta-Regression

(1) Introduction: High sensitivity C-reactive protein (hs-CRP) and CRP are inflammatory biomarkers associated with several inflammatory diseases. In both pediatric and adult individuals with Obstructive Sleep Apnea (OSA) higher hs-CRP and CRP were observed, compared to controls. With the present systematic review, meta-analysis and meta-regression we expand upon previous meta-analyses in four ways: (1) We included 109 studies (96 in adults and 13 in children); (2) we reported subgroup and meta-regression analyses in adults with OSA compared to controls on the serum and plasma levels of hs-CRP; (3) we reported subgroup and meta-regression analyses in adults with OSA compared to controls on the serum and plasma levels of CRP; (4) we reported serum and plasma levels of both hs-CRP and CRP in children with OSA, always compared to controls. (2) Materials and Methods: The PubMed/Medline, Scopus, Cochrane Library, and Web of Science databases were searched to retrieve articles published until 31 May 2020, with no restrictions. The data included basic information involving the first author, publication year, country of study, ethnicity of participants in each study, age, BMI, and AHI of both groups, and mean and standard deviation (SD) of plasma and serum levels of CRP and hs-CRP. (3) Results: A total of 1046 records were retrieved from the databases, and 109 studies were selected for the analysis (96 studies reporting the blood levels of hs-CRP/CRP in adults and 13 studies in children). For adults, 11 studies reported plasma hs-CRP, 44 serum hs-CRP, 9 plasma CRP, and 32 serum CRP levels. For children, 6 studies reported plasma hs-CRP, 4 serum hs-CRP, 1 plasma CRP, and 2 serum CRP levels. Compared to controls, the pooled MD of plasma hs-CRP levels in adults with OSA was 0.11 mg/dL (p < 0.00001). Compared to controls, the pooled MD of serum hs-CRP levels in adults with OSA was 0.09 mg/dL (p < 0.00001). Compared to controls, the pooled MD of plasma CRP levels in adults with OSA was 0.06 mg/dL (p = 0.72). Compared to controls, the pooled MD of serum CRP levels in adults with OSA was 0.36 mg/dL (p < 0.00001). Compared to controls, the pooled MD of plasma hs-CRP, serum hs-CRP, plasma hs-CRP, and serum hs-CRP in children with OSA was 1.17 mg/dL (p = 0.005), 0.18 mg/dL (p = 0.05), 0.08 mg/dL (p = 0.10), and 0.04 mg/dL (p = 0.33), respectively. The meta-regression showed that with a greater apnea-hypapnea index (AHI), serum hs-CRP levels were significantly higher. (4) Conclusions: The results of the present systematic review, meta-analysis and meta-regression showed that compared to healthy controls plasma and serum levels of hs-CRP and serum CRP level were higher in adults with OSA; for children, and compared to controls, just plasma hs-CRP levels in children with OSA were higher.

Splenic infarction associated with obstructive sleep apnoea/hypopnoea syndrome: a case report

Splenic infarction is rare, resulting from occlusion of the splenic artery or its branches. Its aetiology is complex and multifactorial involving various vascular and thrombotic diseases, thus, misdiagnosis or missed diagnosis is common. Here, the case of a 45-year old male patient diagnosed with splenic infarction caused by secondary erythrocytosis associated with obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is reported. The patient presented with 10 days of abdominal distension and pain that worsened after eating, and had developed to include nausea, vomiting and fever. The patient had a history of night snoring for over 10 years without treatment, a diagnosis of chronic pulmonary heart disease and secondary polycythaemia 5 years previously, and diagnosis of OSAHS 1 year previously. He had not received previous non-invasive ventilation or oxygen therapy. Enhanced upper abdomen computed tomography (CT) showed splenic infarction, bone marrow cytology suggested secondary polycythaemia, and sleep polysomnography revealed severe OSAHS. Low molecular-weight heparin, ceftriaxone, fluid and oxygen treatment gradually relieved abdominal distension and pain. Enhanced CT showed splenic infarction improvement. The present case highlights that splenic embolism should not be ignored as a potential complication of OSAHS.

Obstructive sleep apnea, hypertension, resistant hypertension and cardiovascular disease

Obstructive sleep apnea (OSA) is one of the most common causes of hypertension (HTN) and cardiovascular disease (CVD). It is also a quite common underlying factor in resistant HTN (RHTN). The main etiological factor of OSA is obesity, which is a rapidly growing global epidemic. To control obesity, patients should be encouraged by health care professionals to lose weight and be educated about weight loss strategies such as lifestyle modifications, which include regular exercise, low-calorie diet, low sodium intake, smoking cessation, and decreased alcohol consumption. This review also emphasizes the importance of screening for OSA as the major underlying cause of essential, and RHTN, which can lead to CVD and can cause end-organ damage. It also stresses the importance of using continuous positive airway pressure (CPAP) and its beneficial effects, along with other antihypertensive regimens, in treating HTN, and RHTN. Treatment with CPAP therapy decreases sympathetic activity, high blood pressure (BP), heart rate, and CVD as well as its associated mortality.

Endothelial Function of Patients with Morbid Obesity Submitted to Roux-en-Y Gastric Bypass With and Without Obstructive Sleep Apnea-Hypopnea Syndrome

BACKGROUND

Obesity is associated with obstructive sleep apnea-hypopnea syndrome (OSA) and both induce endothelial dysfunction. However, the effect of OSA on endothelial function after bariatric surgery has not been investigated yet.

OBJECTIVES

This study aims to evaluate the impact of weight loss on endothelial function in patients with and without obstructive sleep apnea (OSA) in the first 6 months after bariatric surgery.

SETTING

This study was conducted at a university hospital, in Brazil.

METHODS

The sample consisted of 56 patients homogeneously divided into groups with and without OSA. All patients underwent Roux-en-Y gastric bypass (RYGB), and the diagnosis of OSA was performed by polysomnography. The patients were evaluated preoperatively and 6 months after surgery. The evaluations included anthropometric measures, electrical bioimpedance, clinical symptoms of OSA, and endothelial function (flow-mediated dilation). RYGB improved the anthropometric, bioimpedance, and endothelial function results in both groups.

RESULTS

Patients presented a significant clinical improvement in OSA symptoms throughout the study. However, patients with OSA had an improvement in the endothelial function 2.5% lower (p < 0.001) than patients without APNEA syndrome.

CONCLUSION

This study demonstrates that the existence of OSA prior to bariatric surgery interferes in the improvement of endothelial function.

Cardiovascular endpoints for obstructive sleep apnea with twelfth cranial nerve stimulation (CARDIOSA-12): Rationale and methods

OBJECTIVES/HYPOTHESIS

To determine the effect of therapeutic levels of hypoglossal nerve stimulation therapy (HGNS), compared to subtherapeutic levels of HGNS, on 24-hour ambulatory blood pressure, sympathetic activity, and vascular function.

STUDY DESIGN

Double-blind, sham-controlled, randomized crossover trial of 10-week duration at a university medical center METHODS: The target enrollment is 60 randomly assigned subjects. Interventions are active versus sham (subtherapeutic) HGNS therapy.

RESULTS

The primary outcome is 24-hour ambulatory systolic blood pressure. Secondary outcomes include 24-hour ambulatory diastolic blood pressure, nocturnal systolic and diastolic pressure, muscle sympathetic nerve activity, pre-ejection period, flow-mediated dilation, and pulse wave velocity.

CONCLUSIONS

The Cardiovascular Endpoints for Obstructive Sleep Apnea With Twelfth Cranial Nerve Stimulation study is designed to examine obstructive sleep apnea and test the effects of HGNS on the cardiovascular system through a sham-controlled trial in patients with moderate-severe obstructive sleep apnea.

LEVEL OF EVIDENCE

1 Laryngoscope, 2635-2643, 2018.

Chronic intermittent hypoxia induces hormonal and male sexual behavioral changes: Hypoxia as an advancer of aging

Sleep apnea is a common sleep disorder characterized by intermittent periods of low blood oxygen levels. The risk for sleep apnea increases with age and is more prevalent in men than women. A common comorbidity of sleep apnea includes male sexual dysfunction, but it is not clear if a causal relationship exists between sleep apnea and sexual dysfunction. Possible mechanisms that link these two disorders include oxidative stress and testosterone. Oxidative stress is elevated in clinical patients with sleep apnea and in rodents exposed to chronic intermittent hypoxia (CIH), an animal model for apnea-induced hypopnea. Further, oxidative stress levels increase with age. Therefore, age may play a role in sleep apnea-induced sexual dysfunction and oxidative stress generation. To investigate this relationship, we exposed gonadally intact 3 (young) and 12 (middle-aged) month old male F344/BN F1 hybrid male rats to 8 days of CIH, and then examined male sexual function. Plasma was used to assess circulating oxidative stress and hormone levels. Middle-aged male rats had lower testosterone levels with increased sexual dysfunction and oxidative stress, independent of CIH. However, CIH decreased testosterone levels and increased sexual dysfunction and oxidative stress only in young gonadally intact male rats, but not in gonadectomized young rats with physiological testosterone replacement. In sum, CIH had a greater impact on younger gonadally intact animals, with respect to sexual behaviors, testosterone, and oxidative stress. Our data indicate CIH mimics the effects of aging on male sexual behavior in young gonadally intact male rats.

Is C-reactive protein a marker of obstructive sleep apnea?: A meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) is a common disease, distinguished by recurrent episodes of upper airway obstruction during sleep, with an inflammatory component. C-reactive protein (CRP) and high-sensitivity C-reactive protein (hs-CRP) are markers of systemic inflammation and may serve as biomarkers of OSA.

METHODS

Scientific studies published from January 1, 2006, to January 1, 2016 were obtained via searches of PubMed, Embase, SCI, and China National Knowledge Internet (CNKI) using relevant terms. Studies concerning serum CRP level/ hs-CRP in OSA patients were reviewed by 2 independent reviewers. Studies were included if they conform with our specific criteria of inclusion. Eligible studies were subjected to quality review, data extraction, and meta-analysis by using RevMan (version 5.2) and STATA (version 12.0).

RESULTS

There were 15 studies that met inclusion criteria that included a total of 1297 subjects. Meta-analysis revealed that serum CRP levels in the OSA group were 1.98 mmol/L higher than those in control group (95% confidence interval: 1.39-2.58, P < .01). Similarly, serum hs-CRP levels in the OSA group were 1.57 mmol/L higher than that in the control group (95% confidence interval: 0.96-2.18, P < .01). Subgroup analysis showed greater differences between OSA patients and controls in the setting of obesity (body mass index)> = 30. The total weighted mean difference (WMD) between OSA and controls within the subgroup of subjects who had a CRP was 2.10; for hs-CRP, the WMD was 2.49. Comparing OSA patients of mean apnea hypopnea index> = 15 and controls, the total WMD for the CRP subgroup was 2.19; for the hs-CRP subgroup, the WMD was 1.70.

CONCLUSION

In our meta-analysis, serum CRP/hs-CRP levels were discovered to be higher in OSA patients compared with control subjects. Those with higher body mass index and apnea hyponea index demonstrated larger differences in CRP/hs-CRP levels. These data are consistent with an inflammatory component of OSA pathophysiology and support the role of CRP/hs-CRP as a biomarker in this disease.

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.

Obstructive Sleep Apnea Is Associated with Elevated High Sensitivity C-Reactive Protein Levels Independent of Obesity: Korean Genome and Epidemiology Study

Obstructive sleep apnea syndrome (OSA) has been recognized as a common health problem, and increasing obesity rates have led to further remarkable increases in the prevalence of OSA, along with more prominent cardiovascular morbidities. Though previous studies have reported an independent relationship between elevated high sensitivity C-reactive protein (hsCRP) levels and OSA, the issue remains controversial owing to inadequate consideration of obesity and various confounding factors. So far, few population based studies of association between OSA and hsCRP levels have been published. Therefore, the purpose of the present study was to investigate whether OSA is associated with increased hsCRP levels independent of obesity in a large population-based study. A total of 1,835 subjects (968 men and 867 women) were selected from a larger cohort of the ongoing Korean Genome and Epidemiology Study (KoGES). Overnight polysomnography was performed on each participant. All participants underwent anthropometric measurements and biochemical analyses, including analysis of lipid profiles and hsCRP levels. Based on anthropometric data, body mass index (BMI) and waist hip ratio (WHR) were calculated and fat mass (FM) were measured by means of multi-frequency bioelectrical impedance analysis (BIA). Mild OSA and moderate to severe OSA were defined by an AHI >5 and ≥15, respectively. The population was sub-divided into 3 groups based on the tertile cut-points for the distribution of hsCRP levels. The percentage of participants in the highest tertile of hsCRP increased dose-dependently according to the severity of OSA. After adjustment for potential confounders and obesity-related variables (BMI, WHR, and body fat) in a multiple logistic model, participants with moderate to severe OSA had 1.73-, 2.01-, and 1.61-fold greater risks of being in the highest tertile of hsCRP levels than participants with non-OSA, respectively. Interaction between obesity (BMI ≥25kg/m²) and the presence of moderate-to-severe OSA was significant on the middle tertile levels of hsCRP (OR = 2.4), but not on the highest tertile, compared to the lowest tertile. OSA is independently associated with elevated hsCRP levels and may reflect an increased risk for cardiovascular morbidity. However, we found that OSA and obesity interactively contribute to individuals with general levels of hsCRP (<1.01 mg/dl). The short-term and long-term effects of elevated hsCRP levels on cardiovascular risk in the context of OSA remain to be defined in future studies.

Endothelial function and carotid intima media thickness in obstructive sleep apnea without comorbidity

PURPOSE

The objective of this study was to evaluate endothelial function and carotid intima media thickness (CIMT) in moderate to severe obstructive sleep apnea (OSA) without comorbidities.

METHODS

It is an observational case control study in which endothelial function was assessed using flow-mediated dilatation (FMD) and peripheral arterial tonometry (PAT), and carotid artery ultrasound was used to measure CIMT in study group subjects that included 20 normotensive, non-diabetic, treatment naïve, and moderate to severe OSA patients, and 20 normotensive, non-diabetic, and non-OSA subjects served as a control group. Study was conducted in Polysomnography Laboratory, Department of Internal Medicine, All India Institute of Medical Sciences (AIIMS) Hospital, New Delhi.

RESULTS

FMD was significantly lower in the moderate to severe OSA group compared to non-OSA group (mean ± SD, 8.3 ± 2.8 vs. 13.4 ± 4.1 %; p = 0.0001). Reactive hyperemia index (RHI) was also significantly lower in the OSA group (1.55 ± 0.27 vs. 2.01 ± 0.48, p = 0.0007). CIMT was observed to be significantly higher in the OSA group compared to the non-OSA group (0.54 ± 0.09 vs. 0.48 ± 0.08 mm; p = 0.049). In the OSA group, FMD, RHI, and CIMT did not show a significant correlation with OSA disease severity indices [apnea hypopnea index (AHI), oxygen desaturation index (ODI), and minimum O₂ saturation].

CONCLUSION

Endothelial function in macrovascular and microvascular circulation is significantly impaired in moderate to severe OSA patients without comorbidities. These patients also show evidence of subclinical atherosclerosis, in the form of increased CIMT.

Comparison of Endothelial Function in Asian Indians Versus Caucasians

BACKGROUND

Asian Indians have markedly increased mortality due to coronary artery disease (CAD). Impaired endothelial function has been linked to an increased risk of acute cardiovascular events. We tested the hypothesis that endothelial function was attenuated in Asian Indians and Caucasians.

METHODS

We studied 14 Asian Indians [mean age: 30 ± 6 years; mean body mass index (BMI): 25 ± 3 kg/m(2)] and 11 Caucasians (mean age: 30 ± 5 years; mean BMI: 26 ± 2 kg/m(2)). All 25 subjects were healthy men and nonsmokers without any history of CAD or diabetes and were not taking medications. Endothelial function was evaluated by ultrasound measures of flow-mediated dilatation (FMD) and endothelium-independent nonflow mediated vasodilatation (NFMD) of the brachial artery, in the morning immediately after awakening (6 a.m.) in a fasting state.

RESULTS

Mean age, BMI, apnea-hypopnea index, heart rate, and blood pressure were similar in both groups (P = >0.05). When correcting for body surface area, brachial artery diameter was not different between the two groups (2.1% ± 0.3% vs. 2.2% ± 0.4%; P = 0.29). FMD and NFMD were similar in Asian Indians and Caucasians (5.9% ± 4.1% vs. 5.7% ± 2.6%, P = 0.70; 16.4% ± 8% vs. 14.8% ± 4.1%, P = 0.58, respectively).

CONCLUSION

Endothelial function in Asian Indian men is not attenuated in comparison to Caucasian men.

Erectile Dysfunction and Sexual Hormone Levels in Men With Obstructive Sleep Apnea: Efficacy of Continuous Positive Airway Pressure

In this study, the prevalence of erectile dysfunction (ED) and serum sexual hormone levels were evaluated in men with obstructive sleep apnea (OSA). In these patients, the efficacy of continuous positive airway pressure (CPAP) was determined. The 207 men (mean age 44.0 ± 11.1 years) enrolled in the study were stratified within four groups based on their apnea-hypopnea index score: simple snoring (n = 32), mild OSA (n = 29), moderate OSA (n = 38), and severe OSA (n = 108). The International Index of Erectile Dysfunction-5 (IIEF-5) score was obtained from each patient, and blood samples for the analysis of sexual hormones (prolactin, luteotropin, follicle-stimulating hormone, estradiol, progestin, and testosterone) were drawn in the morning after polysomnography. The IIEF-5 test and serum sexual hormone measurements were repeated after 3 months of CPAP treatment in 53 men with severe OSA. The prevalence of ED was 60.6 % in OSA patients overall and 72.2 % in those with severe OSA. Compared with the simple snoring group, patients with severe OSA had significantly lower testosterone levels (14.06 ± 5.62 vs. 17.02 ± 4.68, p = .018) and lower IIEF-5 scores (16.33 ± 6.50 vs. 24.09 ± 1.94, p = .001). The differences in the other sexual hormones between groups were not significant. After 3 months of CPAP treatment, there were no significant changes in sexual hormone levels, but the IIEF-5 score had improved significantly (18.21 ± 4.05 vs. 19.21 ± 3.86, p = .001). Severe OSA patients have low testosterone concentration and high ED prevalence. IIEF-5 scores increased significantly after CPAP treatment, but there was no effect on serum testosterone levels.

Neck Circumference and Incidence of Diabetes Mellitus over 10 Years in the Korean Genome and Epidemiology Study (KoGES)

Neck circumference, a proxy for upper-body fat, may be a unique fat depot that indicates metabolic risk beyond whole body fat. We investigated whether neck circumference is associated with development of diabetes mellitus (DM) in a subset of data with Korean Genome and Epidemiology Study (n = 3521, age range = 42–71 years). Nondiabetic subjects at the baseline were categorized into 4 groups (Q1–Q4) according to their neck circumference. Parameters related with β-cell function and insulin resistance including Epworth sleepiness scale and snoring habit were examined. The development of DM was confirmed biannually based on a 75-g oral glucose tolerance test. Over the 10 years, 2623 (74.5%) among 3521 subjects were followed-up. Among them, 632 (24.1%) developed DM. The incidence of DM increased from 17.6% in Q1 to 18.2% in Q2, to 25.4% in Q3, and to 36.0% in Q4 (P < 0.001). After adjusting for most risk factors related with DM, the relative risks of DM development were 0.989 (95% confidence interval, 0.638–1.578), 1.660 (1.025–2.687), and 1.746 (1.037–2.942) in men and 0.939 (0.540–1.769), 1.518 (0.808–2.853), and 2.077 (1.068–4.038) in women in Q2, Q3, and Q4, respectively when compared to Q1. This finding indicates negative impact from large neck circumference in the development of DM.

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.

Echocardiographic findings and plasma endothelin-1 levels in obese patients with and without obstructive sleep apnea

OBJECTIVE

Obstructive sleep apnea (OSA) and obesity are increasingly prevalent worldwide. Both promote endothelial dysfunction contributing to systemic and pulmonary hypertension over time. Endothelin-1 (ET-1) plays a pivotal role in the development of pulmonary hypertension (PH). The aim of the present study was to assess the association between plasma ET-1 and echocardiographic findings in obese individuals with and without OSA, as well as in non-obese patients with OSA.

METHODS

Ninety-seven subjects (56 males) were enrolled in the study. All subjects underwent the following tests: venous endothelin-1 levels, pulmonary function testing, and arterial blood gas analysis. All patients except controls underwent transthoracic echocardiography and portable testing for sleep-disordered breathing.

RESULTS

Plasma ET-1 levels were significantly higher in obese patients, both with and without OSA (respectively, n = 30 (mean value, 268.06 ± 49.56 pg/ml) and n = 32 (mean value, 263.12 ± 65.26 pg/ml)), compared with non-obese patients with OSA or to healthy controls (respectively, n = 20 (mean value, 149.8 ± 23.09 pg/ml) and n = 15 (mean value, 152.3 ± 27.64 pg/ml); p < 0.0001). Pulmonary artery pressure (PAPs) in obese patients with OSA were significantly higher than in obese patients without OSA (p < 0.0001), while there was no statistical difference between PAPs of obese patients without OSA, compared with the group of non-obese OSA patients. Plasma ET-1 levels significantly correlated with systolic PAPs in obese patients both with and without OSA (respectively, n = 30, r = 0.385, p = 0.03567; n = 32, r = 0.3497, p = 0.0497).

CONCLUSIONS

Our study suggests that endothelin levels are more strongly associated with weight than the presence of sleep-disordered breathing, but pulmonary artery hypertension is associated with both weight and OSA.

Sex differences of continuous positive airway pressure treatment on flow-mediated dilation in patients with obstructive sleep apnea syndrome

INTRODUCTION

There is growing research evidence suggesting the presence of endothelial dysfunction and systemic inflammation in patients with obstructive sleep apnea syndrome (OSAS). Continuous positive airway pressure (CPAP) is the most effective method for treating OSAS; nonetheless, the effects of CPAP on the aforementioned pathophysiologic pathways as well as on the systemic disease that result or coexist with the OSAS remain elusive.

AIM

To assess the effect of 3-month CPAP therapy on endothelial-dependent dilation, plasma levels of inflammatory markers, blood pressure (BP), and glucose control on male and female patients with OSAS.

METHODS

Our study group consisted of 40 (24 males and 16 females) patients with no prior history of cardiovascular disease, with an apnea-hypopnea index ≥15, who were assigned to receive CPAP treatment. Measurements of flow-mediated dilation (FMD), 24-hour ambulatory BP, and blood analysis were performed at baseline and 3 months after CPAP therapy.

RESULTS

Baseline FMD values were negatively correlated with the apnea-hypopnea index (r=-0.55, P=0.001). After 3 months of CPAP, there was an increase in the FMD values (5.40%±2.91% vs 3.13%±3.15%, P<0.05) and a significant reduction in the patients' 24-hour systolic BP (122.82±11.88 mmHg vs 130.24±16.75 mmHg, P<0.05), diastolic BP (75.44±9.14 mmHg vs 79.68±11.09 mmHg, P<0.05), and pulse pressure (47.38±9.77 mmHg vs 52.72±11.38 mmHg, P<0.05); daytime systolic BP (125.76±12.69 mmHg vs 132.55±17.00 mmHg, P<0.05) and diastolic BP (77.88±10.39 mmHg vs 82.25±11.01 mmHg, P<0.05); nighttime systolic BP (118.17±13.16 mmHg vs 126.22±17.42 mmHg, P<0.05) and pulse pressure (46.61±10.76 mmHg vs 52.66±11.86 mmHg, P<0.05); and C-reactive protein and HbA1c levels (0.40 [0.40-0.70] mg/L vs 0.60 [0.40-0.84] mg/L and 5.45%±0.70% vs 5.95%±1.08%, respectively; P<0.05). When divided by sex, only male patients produced similar statistically significant results, while female patients failed to show such associations.

CONCLUSION

Our results suggest that CPAP therapy improves the endothelial function, the BP, and the glucose control in male patients with OSAS. Further research is warranted in order to verify these results and to further elucidate the impact of CPAP on the cardiovascular risk of male and female patients with OSAS.

Correlation between pentraxin-3 and endothelial dysfunction in obstructive sleep apnea syndrome

BACKGROUND AND AIM

Obstructive sleep apnea syndrome (OSAS) is an independent risk factor for cardiovascular disease. Recent studies showed endothelial dysfunction and pentraxin-3 both of an early marker for development of cardiovascular disease. The aim of the study was to evaluate the relationship between severity of OSAS and endothelial dysfunction and inflammatory markers including pentraxin-3 and high-sensitivity C-reactive protein (hs-CRP).

METHODS

This was a cross-sectional study in which patients who had undergone a polysomnographic study for diagnosis of OSAS were recruited. Included patients were grouped according to apnea-hypopnea index (AHI) as mild (AHI between 5 and 14.9) and moderate-severe OSAS (AHI ⩾ 15). Patients with AHI < 5 served as control group. Endothelial function was evaluated by flow-mediated dilatation (FMD). Serum pentraxin-3 and hs-CRP levels were measured.

RESULTS

Eighty-three patients enrolled for the study. We found a significant increment in pentraxin-3 and hs-CRP levels and a significant decrement in FMD as the severity of OSAS increased. There was a negative correlation between FMD and AHI, pentraxin, and hs-CRP.

CONCLUSION

OSAS patients have significantly elevated pentraxin-3 levels and endothelial dysfunction. Furthermore, both pentraxin-3 and endothelial dysfunction were independently associated with severity of OSAS defined by AHI.

Adipocyte hypoxia promotes epithelial-mesenchymal transition-related gene expression and estrogen receptor-negative phenotype in breast cancer cells

The development of breast cancer is linked to the loss of estrogen receptor (ER) during the course of tumor progression, resulting in loss of responsiveness to hormonal treatment. The mechanisms underlying dynamic ERα gene expression change in breast cancer remain unclear. A range of physiological and biological changes, including increased adipose tissue hypoxia, accompanies obesity. Hypoxia in adipocytes can establish a pro-malignancy environment in breast tissues. Epidemiological studies have linked obesity with basal-like breast cancer risk and poor disease outcome, suggesting that obesity may affect the tumor phenotype by skewing the microenvironment toward support of more aggressive tumor phenotypes. In the present study, human SGBS adipocytes were co-cultured with ER-positive MCF7 cells for 24 h. After co-culture, HIF1α, TGF-β, and lectin-type oxidized LDL receptor 1 (LOX1) mRNA levels in the SGBS cells were increased. Expression levels of the epithelial-mesenchymal transition (EMT)-inducing transcription factors FOXC2 and TWIST1 were increased in the co-cultured MCF7 cells. In addition, the E-cadherin mRNA level was decreased, while the N-cadherin mRNA level was increased in the co-cultured MCF7 cells. ERα mRNA levels were significantly repressed in the co-cultured MCF7 cells. ERα gene expression in the MCF7 cells was decreased due to increased HIF1α in the SGBS cells. These results suggest that adipocytes can modify breast cancer cell ER gene expression through hypoxia and also can promote EMT processes in breast cancer cells, supporting an important role of obesity in aggressive breast cancer development.

Impacts of comorbidities on the association between arterial stiffness and obstructive sleep apnea in the elderly

BACKGROUND

Although the impact of obstructive sleep apnea (OSA) on cardiovascular risk is reasonably well established in middle-aged patients, the debate persists as to whether OSA also increases this risk in the elderly. Arterial stiffness has been used as an early independent predictor of cardiovascular risk.

STUDY OBJECTIVES

We sought to determine whether OSA has significant effects on the arterial stiffness in the elderly population and evaluate the impact of comorbidities on the association between arterial stiffness and OSA.

METHODS

We performed a cross-sectional study in a university hospital. Elderly participants (≥60 years) were invited to participate in our study between November 2010 and January 2013. OSA was diagnosed using gold standard polysomnography and arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV), cardio-ankle vascular index (CAVI) and central systolic and diastolic blood pressure (cSBP and cDBP). The high-sensitivity C-reactive protein (hs-CRP) level was also measured.

RESULTS

We found no significant association between the severity of OSA and the arterial stiffness-related parameters cSBP, cDBP, baPWV, CAVI and hs-CRP. However, in patients with no comorbid medical conditions or use of medications (n = 101), we showed a modest association between OSA and arterial stiffness-related parameters and hs-CRP.

CONCLUSION

We conclude that OSA is associated with increased arterial stiffness in an otherwise healthy elderly population, although the association was obviated by comorbidities and medications perhaps due to ceiling effects.

Sex-specific characteristics of anthropometry in patients with obstructive sleep apnea: neck circumference and waist-hip ratio

OBJECTIVE

This study aimed to investigate the sex-specific effects of anthropometric profiles on the occurrence and severity of obstructive sleep apnea (OSA).

METHODS

We evaluated 151 patients with suspected OSA undergoing polysomnography and anthropometric measurements such as body mass index (BMI), neck and waist circumference (NC and WC), and waist-hip ratio (WHR).

RESULTS

In men, NC (P = .006), WC (P = .035), and WHR (P = .003) were significantly increased in OSA and all were significantly correlated with apnea hypopnea index (AHI). However, in female OSA patients, BMI (P = .05), WC (P = .008), and WHR (P = .001) were elevated, but only WHR was significantly correlated with AHI. Correlation analyses showed significant correlations between NC and other anthropometric indexes in men but not in women. The receiver operating characteristic curves revealed that NC and WHR in men, and WHR in women, were significant in both model I (AHI > or = 5) and model 2 (AHI > or = 15).

CONCLUSION

Waist-hip ratio is the most reliable correlate of OSA in both sexes. Neck circumference is an independent risk factor for male, but not for female, OSA patients. These different aspects of obesity may contribute to the pathogenesis of OSA and provide helpful guidance in the screening of OSA.

Links between ectopic fat and vascular disease in humans

The average of overweight individual can have differential fat depots in target organs or specific compartments of the body. This ectopic fat distribution may be more of a predictive factor for cardiovascular risk than obesity. Abdominal visceral obesity, a representative ectopic fat, is robustly associated with insulin resistance and cardiovascular risk. Fat depots in the liver and muscle tissue cause adverse cardiometabolic risk by affecting glucose and lipid metabolism. Pericardial fat and perivascular fat affect coronary atherosclerosis, cardiac function, and hemodynamics. Fat around the neck is associated with systemic vascular resistance. Fat around the kidney may increase blood pressure and induce albuminuria. Fat accumulation in or around the pancreas alters glucose metabolism, conferring cardiovascular risk. Ectopic fat may act as an active endocrine and paracrine organ that releases various bioactive mediators that influence insulin resistance, glucose and lipid metabolism, coagulation, and inflammation, which all contribute to cardiovascular risk. Because both obese and apparently lean individuals can have ectopic fat, regional fat distribution may play an important role in the development of cardiovascular diseases in both nonobese and obese people.

Pilot study of the effects of bariatric surgery and continuous positive airway pressure treatment on vascular function in obese subjects with obstructive sleep apnoea

BACKGROUND

The mechanisms by which obesity and obstructive sleep apnoea (OSA) may contribute to endothelial dysfunction are unclear.

AIMS

We sought to follow up a sample of obese subjects undergoing either bariatric surgery or continuous positive airway pressure (CPAP) therapy to treat OSA. We hypothesised improved vascular function with both therapeutic approaches, consistent with a reversible OSA effect on the circulation.

METHODS

Twenty-seven obese (BMI ≥30 kg/m(2)) subjects with OSA underwent either bariatric surgery without CPAP (n = 12, median BMI 43.7 kg/m(2) IQR 9.4) or CPAP (n = 15, median BMI 33.8 kg/m(2) IQR 6.6). Polysomnography and vascular testing (flow-mediated dilation of the brachial artery measured with high-resolution ultrasound, endothelium-dependent change in skin blood flow measured with laser Doppler flowmetry, and arterial stiffness measured with applanation tonometry) took place at baseline and after 6 months.

RESULTS

Both groups showed significant improvements in the apnoea-hypopnea index and overnight oxygen saturation. Endothelium-dependent microvascular reactivity was 45.6% (IQR 37.5) at baseline in the CPAP group, which increased to 69.1% (IQR 62.3) post-treatment (P < 0.05). No significant changes were observed in the surgery group, despite significant weight loss (post-surgery BMI 32.7 kg/m2 IQR 8.6 (P < 0.01); no change in BMI was observed in the CPAP group. There were no significant changes in brachial artery flow-mediated dilation in either group.

CONCLUSIONS

This pilot study demonstrates that 6 months of CPAP may be sufficient to improve endothelium-dependent microvascular reactivity, while substantial surgically induced weight loss did not result in improvements. Further research should be directed towards comparative effectiveness trials using these novel surrogate outcomes, as well as hard cardiovascular outcomes.

TST, as a polysomnographic variable, is superior to the apnea hypopnea index for evaluating intermittent hypoxia in severe obstructive sleep apnea

The polysomnography (PSG) index of the apnea hypopnea index (AHI) is considered the 'gold standard' for stratifying the severity of obstructive sleep apnea (OSA). However, AHI cannot reflect the true characteristic of chronic intermittent hypoxia (CIH), which may trigger systemic inflammation in some OSA patients. High-sensitivity C-reactive protein (hsCRP) is considered a biomarker of systemic inflammation in OSA patients. The aim of the present study was to evaluate the relationship between PSG variables and hsCRP in men with severe OSA. Men with severe OSA (AHI ≥ 30 events/h) diagnosed by PSG were enrolled. AHI and body mass index were matched between a high hsCRP group (hsCRP ≥ 3.0 mg/L) and a low hsCRP group. A blood sample was taken for serum hsCRP analysis. Multiple regression analysis was performed to assess independent predictors of high hsCRP. One hundred and fifty-two subjects were enrolled in the study (76 in each group). Mean serum hsCRP was 3.76 ± 2.13 mg/L. The mean percentage of total sleep time spent with SaO2 <90% (TST) in the high hsCRP group was significantly higher than in the low hsCRP group (20.99 ± 18.52 vs. 5.84 ± 7.30, p < 0.001). Multivariate analysis showed that TST was the strongest predictor, contributing to 27.7% of hsCRP variability (β = 0.496, p < 0.01). TST may be superior to AHI for evaluating CIH among OSA patients. The severity of OSA should be stratified by a combination of AHI and other hypoxia variables.

Association between obstructive sleep apnea severity and endothelial dysfunction in an increased background of cardiovascular burden

The objective of this study is to examine whether increasing obstructive sleep apnea (OSA) severity is associated with worsening endothelial function. The design is a cross-sectional examination of the baseline assessment of a multi-centre randomized controlled clinical trial examining the effects of oxygen, continuous positive airway pressure (CPAP) therapy or lifestyle modifications on cardiovascular biomarkers. Participants were recruited from cardiology clinics at four sites. Participants with an apnea-hypopnea index (AHI) of 15-50 and known cardio/cerebrovascular disease (CVD) or CVD risk factors were included. OSA severity indices [oxygen desaturation index (ODI), AHI and percentage of sleep time below 90% oxygen saturation (total sleep time <90)] and a measure of endothelium-mediated vasodilatation [Framingham reactive hyperaemia index (F-RHI) derived from peripheral arterial tonometry (PAT)] were assessed. The sample included 267 individuals with a mean AHI of 25.0 ± 8.5 SD and mean F-RHI 0.44 ± 0.38. In adjusted models, the slope of the relationship between ODI and F-RHI differed above and below an ODI of 24.6 (P = 0.04), such that above an ODI of 24.6 there was a marginally significant decline in the geometric mean of the PAT ratio by 3% [95% confidence interval (CI): 0%, 5%; P = 0.05], while below this point, there was a marginally significant incline in the geometric mean of the PAT ratio by 13% (95% CI: 0%, 27%; P = 0.05) per 5-unit increase in ODI. A similar pattern was observed between AHI and F-RHI. No relation was noted with total sleep time <90 and F-RHI. There was evidence of a graded decline in endothelial function in association with higher levels of intermittent hypoxaemia.

Effect of CPAP treatment on endothelial function and plasma CRP levels in patients with sleep apnea

BACKGROUND

Continuous positive airway pressure (CPAP) is the most effective method for treating obstructive sleep apnea syndrome (OSAS) and alleviating symptoms. Improved sleep quality with effective CPAP therapy might also contribute to attenuated systemic inflammation and improved endothelial function, with subsequent reduction of cardiovascular risk. The aim of this study was to assess the effect of 3-month CPAP therapy on brachial artery flow-mediated dilation (FMD) and plasma C-reactive protein (CRP) levels in patients with OSAS.

MATERIAL/METHODS

Our study group consisted of 38 male patients with no prior history of cardiovascular disease. Twenty patients with an Apnea-Hypopnea Index (AHI) ≥15 were assigned to receive CPAP treatment and 18 subjects with an AHI<5 were included in the control group. Six patients failed to comply with the CPAP treatment. Measurement of FMD and blood analysis was performed at baseline and 3 months after CPAP therapy.

RESULTS

Baseline FMD values were negatively correlated with age, BMI, AHI, DSI,% of time <90% Sa02, and CRP (p<0.05). Plasma CRP values were positively correlated with BMI, AHI, DSI and% of time <90% Sa02 (p<0.05). In the group of patients who complied with the CPAP treatment, there was a significant increase in the FMD values (9.18 ± 0.55 vs. 6.27 ± 0.50) and a decrease in the levels of CRP (0.67 ± 0.15 vs. 0.84 ± 0.18) (p<0.05).

CONCLUSIONS

Appropriate CPAP therapy improved both CRP and FMD values, suggesting its potentially beneficial role in reducing cardiovascular risk in OSAS patients.

Endothelial function is well preserved in obese patients with mild obstructive sleep apnea

PURPOSE

Endothelial dysfunction is one of the early markers of cardiovascular complications in obstructive sleep apnea (OSA). The aim of our study was to evaluate whether overweight patients with mild OSA displayed endothelial dysfunction, and to assess the effect of 1-year lifestyle intervention with an early very low calorie diet in endothelial function.

METHODS

At baseline, the study population consisted of 83 overweight patients with mild OSA and 46 weight-matched non-OSA subjects. OSA patients were further randomized into a 1-year supervised lifestyle intervention group or control group which received routine lifestyle counselling. Endothelial function measured by brachial artery flow-mediated dilatation (FMD), apnea-hypopnea index (AHI), body mass index (BMI), and metabolic parameters were assessed at baseline and 12 months.

RESULTS

No correlations between endothelial function and mild OSA were detected. However, patients with impaired endothelial function had lower mean saturation and impaired endothelial function correlated significantly with glucose intolerance and dyslipidemia. After the lifestyle intervention and successful weight reduction, AHI, BMI, serum triglycerides and insulin improved significantly; however, no improvement in FMD was detected.

CONCLUSIONS

Mild OSA was not observed to be associated with endothelial dysfunction. Although in mild OSA endothelial function is still preserved, lifestyle intervention with weight reduction did achieve an improvement in other obesity-related risk factors for cardiovascular diseases, thus highlighting the importance of early intervention.

Atorvastatin protects against deleterious cardiovascular consequences induced by chronic intermittent hypoxia

Chronic intermittent hypoxia (IH), a major component of obstructive sleep apnea (OSA), contributes to the high risk of cardiovascular morbidity. We have previously demonstrated that IH-induced oxidative stress is involved in the hypertension and in the hypersensitivity to myocardial infarction. However, the mechanisms underlying these cardiovascular alterations are still unclear, as well as the role of potential protective treatment. Atorvastatin has pleiotropic actions, including increasing nitric oxide (NO) bioavailability and reducing inflammation and oxidative damage. The aim of this study was to evaluate the beneficial effect of a two time course of this treatment against the deleterious cardiovascular consequences of IH. Rats were divided into two groups subjected to chronic IH or normoxic (N) exposure. IH consisted of repetitive one-minute cycles (with only 30 s of a 5% inspired O2 fraction) and was applied for eight hours during daytime, for 14 (simultaneous protocol) or 28 d (delayed protocol). Atorvastatin (10 mg/kg/ d) or its vehicle was administered during the 14 d simultaneous protocol or the last 14 d of the delayed protocol. For both protocols, systolic arterial pressure was significantly increased by 14 d IH exposure. Atorvastatin prevented this deleterious effect in the simultaneous protocol. Carotid artery compliance and endothelial function were significantly altered after 28 d but not after 14 d of IH exposure. Delayed atorvastatin administration preserved these vascular parameters. IH also increased hypersensitivity to myocardial infarction after 14 d exposure, and atorvastatin abolished this deleterious effect. IH also enhanced cardiac NADPH expression and decreased aortic superoxide dismutase activity after 14 d exposure. Atorvastatin significantly restored these activities. In conclusion, whereas IH rapidly increased blood pressure, myocardial infarction hypersensitivity and oxidative stress, compliance, endothelial function and the structural wall of the carotid artery were only altered after a longer IH exposure. Atorvastatin prevented all these deleterious cardiovascular effects, leading to a potentially novel pharmacological therapeutic strategy for OSA syndrome.

Correlation between endothelial dysfunction, Rho-associated protein kinase activity, C-reactive protein and obstructive sleep apnoea syndrome in male patients

OBJECTIVE

This study investigated the association between obstructive sleep apnoea syndrome (OSAS) and flow-mediated dilatation (FMD), Rho-associated protein kinase (ROCK) activity, and C-reactive protein (CRP) concentrations in male patients.

METHODS

Consecutive patients with symptoms suggestive of OSAS were recruited and divided into non-OSAS (n = 18) and OSAS (n = 32) groups. FMD was measured in the brachial artery; blood samples were taken to measure ROCK activity and CRP concentrations.

RESULTS

ROCK activity and CRP concentrations were significantly higher, and FMD was significantly lower, in the OSAS group than in the non-OSAS group. There was a correlation between ROCK activity and FMD. In stepwise multiple regression analyses, the proportion of sleep time spent with an oxygen saturation < 90% was a significant determinant of ROCK activity, while body mass index was the only significant determinant of CRP concentration. The oxygen desaturation index was a significant determinant of FMD.

CONCLUSIONS

OSAS increased ROCK activity and was a major determinant of endothelial dysfunction.

Obstructive sleep apnea syndrome (OSAS) and hypertension: pathogenic mechanisms and possible therapeutic approaches

Obstructive sleep apnea syndrome (OSAS), a chronic condition characterized by collapse of the pharynx during sleep, has been increasingly recognized as a health issue of growing importance over the last decade. Recently emerging evidence suggests that there is a causal link between OSAS and hypertension, and hypertension represents an independent risk factor in OSAS patients. However, the pathophysiological basis for patients with OSAS having an increased risk for hypertension remains to be elucidated. The main acute physiological outcomes of OSAS are intermittent hypoxia, intrapleural pressure changes, and arousal from sleep, which might induce endothelial dysfunction, sympathetic activation, renin-angiotensin-aldosterone system activation, lipid metabolism dysfunction, and increased oxidative stress. This brief review focuses on the current understanding of the complex association between OSAS and hypertension.

Coagulability in obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a common disorder that affects both quality of life and cardiovascular health. The causal link between OSA and cardiovascular morbidity⁄mortality remains elusive. One possible explanation is that repeated episodes of nocturnal hypoxia lead to a hypercoagulable state that predisposes patients to thrombotic events. There is evidence supporting a wide array of hematological changes that affect hemostasis (eg, increased hematocrit, blood viscosity, platelet activation, clotting factors and decreased fibrinolytic activity).

OBJECTIVE

To provide a comprehensive review of the current evidence associating OSA with increased coagulability, and to highlight areas for future research.

METHODS

Keyword searches in Ovid Medline were used to identify relevant articles; all references in the articles were searched for relevant titles. The Web of Science was used to identify articles citing the relevant articles found using the Ovid Medline search. All original peer-reviewed articles, meta-analyses and systematic reviews regarding the pertinent topics between 1990 and present were selected for review.

RESULTS

Hematocrit, blood viscosity, certain clotting factors, tissue factor, platelet activity and whole blood coagulability are increased in patients with OSA, while fibrinolysis is impaired.

CONCLUSION

There is considerable evidence that OSA is associated with a procoagulant state. Several factors are involved in the procoagulant state associated with OSA. There is a need for adequately powered clinical studies involving well-matched control groups to address potential confounding variables, and to accurately delineate the individual factors involved in the procoagulant state associated with OSA and their response to treatment.

Oxidative stress mediated arterial dysfunction in patients with obstructive sleep apnoea and the effect of continuous positive airway pressure treatment

Background

Several studies suggest an increase of oxidative stress and a reduction of endothelial function in obstructive sleep apnoea syndrome (OSAS). We assessed the association between OSAS, endothelial dysfunction and oxidative stress. Further aim was to evaluate the effect of nasal continuous positive airway pressure (nCPAP) on oxidative stress and arterial dysfunction.

Methods

We studied 138 consecutive patients with heavy snoring and possible OSAS. Patients underwent unattended overnight home polysomnography. Ten patients with severe OSAS were revaluated after 6 months of nCPAP therapy. To assess oxidative stress in vivo, we measured urinary 8-iso-PGF2α and serum levels of soluble NOX2-derived peptide (sNOX2-dp). Serum levels of nitrite/nitrate (NOx) were also determined. Flow-mediated brachial artery dilation (FMD) was measured to asses endothelial function.

Results

Patients with severe OSAS had higher urinary 8-iso-PGF2α (p<0.001) and serum NOX2 and lower NOx. A negative association was observed between FMD and OSA severity. Apnea/hypopnea index was significantly correlated with the indices of central obesity and with urinary 8-isoprostanes (r=0.298, p<0.001). The metabolic syndrome (t=-4.63, p<0.001) and urinary 8-isoprostanes (t=-2.02, p<0.05) were the only independent predictors of FMD. After 6-months nCPAP treatment, a significant decrease of serum NOX2, (p<0.005) and urinary 8-iso-PGF2α (p<0.01) was observed, while serum NOx showed only a minor increase. A statistically significant increase of FMD was observed (from 3.6% to 7.0%).

Conclusions

The results of our study indicate that patients with OSAS and cardiometabolic comorbidities have increased oxidative stress and arterial dysfunction that are partially reversed by nCPAP treatment.

Effect of continuous positive airway pressure on C-reactive protein levels in sleep apnea: a meta-analysis

OBJECTIVE

Evaluate the effects of continuous positive airway pressure (CPAP) on C-reactive protein (CRP) levels, reported either as a primary or secondary end point among patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) based on a meta-analysis of published studies.

DATA SOURCES

English-language searches of PubMed, Ovid, and the Cochrane databases were completed. Reference sections of identified studies were also examined for additional relevant articles to review.

REVIEW METHODS

Studies of adult patients with OSAHS who reported pre- and post-CPAP treatment CRP were reviewed and analyzed. Two independent reviewers extracted data from 10 peer-reviewed studies, which were combined using a random effects meta-analysis model.

RESULTS

The CPAP treatment was found to lead to a significant reduction in CRP levels (17.8%, P = .002). This corresponds to an effect size of -0.485 (-0.731, -0.240). Sensitivity analysis was done to determine the impact of study design. Both case-control studies and case-series studies yielded a significant effect. Sensitivity analysis also yielded a significant effect for studies with average body mass index <30, studies where CPAP was employed over automatic positive airway pressure, and studies treating patients ≤ 3 months. Analysis of publication bias, however, revealed a likelihood of "missing" studies.

CONCLUSION

Although there is a significant lack of high-quality studies addressing this question, this analysis suggests that treatment with CPAP leads to a statistically significant reduction in CRP levels. However, the mean pre- and posttreatment CRP levels observed are considered "high risk" for cardiovascular morbidity. The clinical significance of this finding as it relates to cardiovascular risk reduction and the relationship between CRP and OSAHS requires further study.

C-reactive protein (CRP) is a predictor of high medical-care expenditures in a community-based elderly population aged 70 years and over: the Tsurugaya project

Because CRP is a strong independent predictor of various diseases, it was hypothesized that CRP may be a useful predictor or treatment target for medical-care expenditures. The aim of this study was to investigate the relationship between CRP and medical-care expenditures in a community-dwelling elderly population. This prospective cohort study was conducted including 925 Japanese subjects aged ≥70 years. A high-sensitivity CRP assay was used by applying the nephelometric method. Hospitalizations, outpatient visits, and expenditures were ascertained through computerized linkage with claims lodged between August 2002 and March 2008 with the Miyagi National Health Insurance (NHI) Association. Since medical-care expenditures were not normally distributed, the category of high medical-care expenditures (>75th percentile of medical-care expenditures: inpatient expenditures >$494/month; outpatient expenditure >$522/month; total expenditures >$1103/month) was used to examine the relation of CRP levels with medical-care expenditures. Multiple logistic regression analysis was used to examine the relationship between CRP cutoff points (low concentrations: <1.0mg/L; intermediate concentrations: 1.0-3.0mg/L; or high concentrations: ≥3.0 mg/L) and medical-care expenditures during 6 year-follow up period. After adjustment for potential confounding factors, a positive association of CRP with hospitalization, and total expenditures (p for trend=0.03 and 0.02, respectively) was found. An elevated baseline CRP level is an independent predictor of increases in prospective medical-care expenditures among community-dwelling elderly. Further study is required to clarify whether reducing CRP by intervention is a cost-effective measure.

Effect of Adenotonsillectomy on Endothelin-1 and C-Reactive Protein Levels in Children with Sleep-Disordered Breathing

Objective. This study aimed to evaluate the influence of adenotonsillectomy on the plasma concentration of endothelin-1 (ET-1) and C-reactive protein (CRP) in children with sleep-disordered breathing (SDB). The relationship between quality of life and ET-1 levels was also evaluated.

Setting. Tertiary referral center.

Study Design. Before-and-after case series.

Methods. Fasting blood samples for ET-1 and high-sensitivity CRP were drawn preoperatively in all patients and at 3 to 4 months postoperatively. The Obstructive Sleep Apnea–18 (OSA-18) survey and Brouilette symptom score were completed by each child’s parents during the same time periods.

Results. The mean ET-1 level decreased from 3.51 ± 0.93 fmol/mL to 2.67 ± 0.69 fmol/mL postoperatively ( P < .01). OSA-18 survey scores and Brouilette symptom scores also decreased in the postoperative period ( P < .01). When comparing moderate and severe cases to mild cases according to Brouilette scores, ET-1 levels were significantly higher in moderate and severe cases ( P < .01). There was a significant correlation between ET-1 and the OSA-18 survey scale ( r = 0.442; P = .001). Although CRP levels decreased from 0.63 ± 1.19 mg/dL to 0.31 ± 0.23 mg/dL postoperatively, this was not statistically significant.

Conclusion. Adenotonsillectomy effectively lowered plasma ET-1 levels in children with SDB and thus may have reduced their related risk for cardiovascular disease. In addition, adenotonsillectomy improved quality of life in this group.

Inflammatory pathways in children with insufficient or disordered sleep

Sleep is not only an essential physiological function, but also serves important roles in promoting growth, maturation, and overall health of children and adolescents. There is increasing interest regarding the impact of sleep and its disorders on the regulation of inflammatory processes and end-organ morbidities, particularly in the context of metabolic and cardiovascular diseases (CVD) and their complications. Obstructive sleep apnea syndrome (OSAS) is an increasingly common health problem in children, and in the last decade, the emergence of increasing obesity rates has further led to remarkable increases in the prevalence of OSAS, along with more prominent neurocognitive, behavioral, cardiovascular and metabolic morbidities. Although the underlying mechanisms leading to OSAS-induced morbidities are likely multi-factorial, and remain to be fully elucidated, activation of inflammatory pathways by OSAS has emerged as an important pathophysiological component of the end-organ injury associated with this disorder. To this effect, it would appear that OSAS could be viewed as a chronic, low-grade inflammatory disorder. Furthermore, the concurrent presence of obesity and OSAS poses a theoretically increased risk of OSAS-related complications. In this review, we will critically review the current state of research regarding the impact of insufficient and disrupted sleep and OSAS on the immune processes and inflammatory pathways that underlie childhood OSAS as a distinctive systemic inflammatory condition in children, and will explore potential interactions between OSAS and obesity.

Patients with obstructive sleep apnea exhibit impaired endothelial function after myocardial infarction

BACKGROUND

Impaired brachial flow-mediated dilation (FMD) is associated with risk for subsequent cardiovascular events in patients after myocardial infarction (MI). These patients often have obstructive sleep apnea (OSA). We tested the hypothesis that patients with OSA post MI will exhibit more severe impairment in FMD.

METHODS

We studied 64 patients with MI admitted to our hospital. OSA was determined using polysomnography. FMD was measured using high-resolution ultrasonography, with researchers blind to the OSA diagnosis.

RESULTS

The mean age was 60 ± 11 years, and the mean BMI was 29 (26, 32 kg/m(2)), 84% of patients were men, 39% had moderate to severe OSA (apnea-hypopnea index [AHI] > 15), and 31% of the patients had mild OSA (5 ≤ AHI < 15). FMD was severely impaired in patients with moderate to severe OSA (0.8% ± 0.7%) as compared with patients without OSA (4.7% ± 0.8%, P = .001) and with mild OSA (3.9% ± 0.8%, P = .015). Linear regression showed that FMD was associated with log nocturnal nadir oxygen saturation (minSaO(2)) (β = 31.17, P = .0001), age (β = -0.11, P = .006). MinSaO(2) was an independent predictor of FMD after adjustment for possible confounders (β = 26.15, P = .001).

CONCLUSIONS

FMD is severely impaired in patients with moderate to severe OSA post MI, which may be partially related to nocturnal hypoxemia. Patients with OSA may, therefore, be at higher risk for subsequent cardiovascular events after an MI. Identifying and treating OSA may have important implications in the long-term prognosis of patients post MI. Further studies are necessary to determine if the presence of OSA would affect the long-term occurrence of cardiovascular events after an MI.

Severity of obstructive sleep apnea syndrome and high-sensitivity C-reactive protein reduced after relocation pharyngoplasty

OBJECTIVES

To report improvement of obstructive sleep apnea syndrome (OSAS) and changes of high-sensitivity C-reactive protein (hs-CRP) concentrations after relocation pharyngoplasty (RP), a high variant of uvulopalatopharyngoplasty.

STUDY DESIGN

Prospective comparative study.

SETTING

Tertiary referral center.

SUBJECTS AND METHODS

Thirty consecutive OSAS patients without a preexisting diagnosis of cardiovascular disease who underwent RP were assessed for body mass index (BMI), Epworth Sleepiness Scale (ESS), sleep apnea-hypopnea index (AHI), and serum levels of hs-CRP at baseline and 6 months postoperatively.

RESULTS

Of the subjects, the mean values of age, BMI, ESS, AHI, and hs-CRP were 39.5 ± 7.0 years, 27.5 ± 4.5 kg/m(2), 10.8 ± 4.2, 46.2 ± 22.9 events/hour, and 2.06 ± 1.78 mg/L, respectively. After 6 months postoperatively, RP reduced the ESS (Δ = -4.3 ± 4.5, P < .001) and AHI (Δ = -28.3 ± 21.1, P < .001) and levels of hs-CRP (Δ = -0.67 ± 1.36, P = .012) significantly, whereas BMI measurements were indifferent (Δ = -0.42 ± 1.28, P = .073). Moreover, the changes of AHI and hs-CRP were particularly remarkable in patients with very severe OSAS (AHI ≥60).

CONCLUSION

Although many OSAS patients remain in the mild-moderate category, equivalent improvements in excessive daytime sleepiness and reductions of hs-CRP concentrations indicate that reduction of AHI is not all that matters after RP.

Patients with venous thromboembolism appear to have higher prevalence of obstructive sleep apnea than the general population

INTRODUCTION

The link between obstructive sleep apnea (OSA) and venous thromboembolism (VTE) remains unclear. We sought to study a possible association between VTE and OSA.

METHODS

We retrospectively collected data on patients with VTE between 1999 and 2009. Data on demographics and comorbidities were recorded as well as body mass index was calculated. Primary outcome was prevalence of OSA defined as an apnea-hypopnea index (AHI) ≥5. The study was registered at clinicaltrials.gov (NCT01051297).

RESULTS

We identified 840 patients with VTE. Obstructive sleep apnea was confirmed in 130 (15.5% [13%-17.9%]). Compared to the control group (no OSA), those who had OSA were more obese (83.8% vs 43.8%) and had statistically higher prevalence of diabetes, coronary artery disease, and congestive heart failure.

CONCLUSIONS

The prevalence of OSA 15.5% (13%-17.9%) appears to be higher than that of the general population among patients with VTE. Our findings suggest a possible link between OSA and VTE.

The effects of nasal continuous positive airway pressure on vascular functions and serum cardiovascular risk factors in obstructive sleep apnea syndrome

PURPOSE

We investigated whether the nasal continuous positive airway pressure (nCPAP) could have impacts on impaired vascular functions and serum cardiovascular risk factors in obstructive sleep apnea syndrome (OSAS).

METHODS

We enrolled 25 OSAS patients of moderate to severe degree. After polysomnography, carotid-femoral pulse wave velocity (cfPWV) and flow-mediated dilation (FMD) were measured. Also, serum levels of C-reactive protein (CRP), total cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, glucose, and insulin were measured. After nCPAP treatment (mean duration, 138.7 ± 42.6 days), these tests were performed again.

RESULTS

The mean apnea hypopnea index prior to nCPAP was 64.9 ± 20.0/h, which decreased to 4.1 ± 2.0/h with nCPAP (p < 0.001). After nCPAP, cfPWV (m/s) decreased from 11.2 ± 4.5 to 9.3 ± 2.1 (p = 0.031), and FMD (%) was improved from 5.52 ± 2.49 to 6.58 ± 2.50 (p = 0.006). Body mass index, serum levels of CRP, total cholesterol, triglyceride, HDL cholesterol, or glucose did not change after nCPAP. Insulin resistance was not improved either.

CONCLUSIONS

The cfPWV and FMD were significantly improved after nCPAP treatment, even though there was no significant change in body weight or serum cardiovascular risk factors. The nCPAP treatment could decrease risks of cardiovascular complications in OSAS patients through improving vascular functions.