Association between lipid peroxidation and inflammation in obstructive sleep apnoea

TRIM24 upregulates ORM2 to alleviate abnormal lipid metabolism, inflammation, and oxidative stress in mice with obstructive sleep apnea syndrome & metabolic dysfunction-associated steatotic liver disease

Obstructive sleep apnea syndrome (OSAS) is associated with the development and progression of metabolic dysfunction-associated steatotic liver disease (MASLD). Tripartite Motif Containing 24 (TRIM24) deficiency was reported to cause hepatic lipid accumulation and hepatitis. However, the expression, function, and mechanism of TRIM24 in OSAS & MASLD remain unclear. OSAS & MASLD mouse model was established by intermittent hypoxia (IH) & high-fat diet. IH- & 1% free fatty acid-induced mouse liver cells were served as in vitro model. TRIM24 and HIF-1α were upregulated under IH condition. HIF-1α enhanced the transcriptional activity of TRIM24. Overexpression of TRIM24 reduced hepatic lipid accumulation, decreased serum levels of TC, TG, and LDL-C, and increased serum levels of HDL-C in OSAS & MASLD mice. Additionally, overexpression of TRIM24 alleviated inflammation, oxidative stress, and modulated aberrant lipid metabolism. Mechanically, TRIM24 upregulated the expression of ORM2, a key regulator of hepatic lipogenesis, by binding to H3K27ac and recruiting RAR-alpha to ORM2 promoter. The cell rescue model verified that ORM2 mediated the hepatoprotective effects of TRIM24. Our evidence reveals the important role of TRIM24 as an epigenetic co-regulator of transcription in OSAS & MASLD, providing additional insights into understanding the pathogenesis and preventing the development of OSAS & MASLD.

Ethanolic Extract from Fruits of Pintoa chilensis, a Chilean Extremophile Plant. Assessment of Antioxidant Activity and In Vitro Cytotoxicity

Pintoa chilensis is a shrub with yellow flowers that reach up to two meters high, endemic of the Atacama Region in Chile. This species grows under special environmental conditions such as low altitude, arid areas, and directly sun-exposed habitats. In the present study, ethanolic extract was obtained from fruits of P. chilensis, and then partitioned in solvents of increasing polarity to obtain five fractions: hexane (HF), dichloromethane (DF), ethyl acetate (AF), and the residual water fraction (QF). The antioxidant activity of extracts was evaluated by using the DPPH, ABTS, and FRAP methods. The results show that the antioxidant capacity of P. chilensis is higher than that reported for other plants growing in similar environments. This effect is attributed to the highest content of flavonoids and total phenols found in P. chilensis. On the other hand, the cell viability of a breast cancer cell line (MCF-7) and a non-tumor cell line (MCF-10A) was assessed in the presence of different extract fractions. The results indicate that the hexane fraction (HF) exhibits the highest cytotoxicity on both cell lines (IC50 values equal to 35 and 45 µg/mL), whereas the dichloromethane fraction (DF) is the most selective one. The GC-MS analysis of the dichloromethane fraction (DF) shows the presence of fatty acids, sugars, and polyols as major components.

Association of Obstructive Sleep Apnea-Hypopnea Syndrome with hearing loss: A systematic review and meta-analysis

Objective

This study seeks to investigate the relationship between Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) and hearing impairment by meta-analysis.

Methods

Cochrane Library, PubMed, Embase, Web of Science and other databases are searched from their establishment to July 1st, 2022. Literature on the relationship between OSAHS and hearing loss is collected, and two researchers independently perform screening, data extraction and quality evaluation on the included literature. Meta-analysis is performed using RevMan 5.4.1 software. According to the heterogeneity between studies, a random-effects model or fixed-effects model is used for meta-analysis.

Results

A total of 10 articles are included, with 7,867 subjects, 1,832 in the OSAHS group and 6,035 in the control group. The meta-analysis shows that the incidence of hearing impairment in the OSAHS group is higher than in the control group (OR = 1.38; 95% CI 1.18–1.62, Z = 4.09, P < 0.001), and the average hearing threshold of OSAHS patients is higher than that of the control group (MD = 5.89; 95% CI 1.87–9.91, Z = 2.87, P = 0.004). After stratifying the included studies according to hearing frequency, the meta-analysis shows that the OSAHS group has a higher threshold of 0.25, and the response amplitudes at frequencies 2, 4, 6, and 8 kHz are all higher than those of the control group.

Conclusion

Compared with the control group, the OSAHS group has a higher incidence of hearing loss, mainly high-frequency hearing loss. Thus, OSAHS is closely associated with and a risk factor for hearing loss.

Profiling inflammatory and oxidative stress biomarkers following taurine supplementation: a systematic review and dose-response meta-analysis of controlled trials

Taurine (Tau) has modulatory effects on inflammatory and oxidative stress biomarkers; however, the results of clinical studies are not comprehensive enough to determine the effect of different durations and doses of Tau supplementation on inflammatory and oxidative stress biomarkers. The current study was conducted based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. For this purpose, PubMed/Medline, Scopus, and Embase databases were systematically searched to obtain the relevant studies published before 30th March 2021. Meta-analysis was performed on controlled clinical trials by using the random-effects method. Non-linear relationship between variables and effect size was performed using dose-response and time-response analyses. The Cochrane Collaboration's tool was used to evaluate the quality of included studies. Tau supplementation can reduce the levels of malondialdehyde (MDA) (SMD = -1.17 µmol/l; 95% CI: -2.08, - 0.26; P = 0.012) and C-reactive protein (CRP) (SMD = -1.95 mg/l; 95% CI: -3.20, - 0.71; P = 0.002). There have been no significant effects of Tau supplementation on the levels of tumor necrosis factors-alpha (TNF-α) (SMD = -0.18 pg/ml; 95% CI: -0.56, 0.21; P = 0.368), and interleukin-6 (IL-6) (SMD = -0.49 pg/ml; 95% CI: -1.13, 0.16; P = 0.141). Besides, Tau has more alleviating effect on oxidative stress and inflammation on 56 days after supplementation (P < 0.05). Tau can decrease the levels of CRP and MDA. Based on the currently available evidence, Tau has no significant effect on the level of TNF-α and IL-6. Eight-week of Tau supplementation has more beneficial effects on inflammatory and oxidative stress biomarkers.

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

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

Sleep apnea, coronary artery calcium density and cardiovascular events: results from the Multi-Ethnic Study of Atherosclerosis (MESA)

STUDY OBJECTIVES

Evaluate the association between obstructive sleep apnea (OSA), coronary artery calcium (CAC) density, and cardiovascular events in the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS

We analyzed 1041 participants with non-zero CAC scores who had polysomnography and CAC density data from the fifth examination of MESA. OSA was defined as apnea-hypopnea index [AHI] ≥ 15 events/hour. Multivariable linear regression models were used to evaluate the independent association between OSA and CAC density. Additionally, we evaluated the impact of OSA on associations of CAC measures with incident CVD events by testing for interaction in Cox proportional hazard regression models.

RESULTS

Our analytical sample was 45% female with a mean age of 70.6 +/- 9 years. Of this sample, 36.7% (n=383/1041) had OSA (AHI≥15). OSA was inversely and weakly associated with CAC density (β= -0.09, 95% CI -0.17 to -0.02, p=0.014) and remained significantly associated after controlling for traditional cardiovascular risk factors (β= -0.08, 95% CI -0.16 to 0, p=0.043). However, this inverse association was attenuated after controlling for BMI (β=-0.05, 95% CI -0.13 to 0.02, p=0.174). The mean follow-up period for CVD events was 13.3 +/- 2.8 years. Additionally, exploratory analysis demonstrated that CAC density was independently and inversely associated with CVD events only in the non-OSA subgroup (AHI≤15) (HR 0.509 [CI 0.323 - 0.801], p=0.0035).

CONCLUSIONS

OSA was associated with lower CAC density, but this association was attenuated by BMI. Further, increased CAC density was associated with a reduced risk of CVD events only in individuals within the non-OSA group in exploratory analysis.

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.

The impact of sleep disorders on microvascular complications in patients with type 2 diabetes (SLEEP T2D): the protocol of a cohort study and feasibility randomised control trial

BACKGROUND

Obstructive sleep apnoea (OSA) is very common in patients with type 2 diabetes (T2D). We and others have shown that OSA was associated with diabetes-related microvascular complications in patients with T2D in cross-sectional and longitudinal studies and that compliance with continuous positive airway pressure (CPAP) reduced the progression of microvascular complications. Hence, we hypothesised that adequate CPAP reduces the development of microvascular complication in patients with T2D.

METHODS

SLEEP T2D is a cohort study with embedded feasibility, open-label, parallel-arm, randomised control trial (RCT) over 2 years. The primary aim is the feasibility of conducting a definitive RCT assessing the impact of CPAP on chronic kidney disease and other microvascular complications in patients with T2D. The main parameters are to assess willingness of participants to be randomised, follow-up rates, CPAP adherence/compliance, to optimise the choice of outcome measures for a substantive trial, and to identify the parameters for sample size calculations. The secondary aims of the study are related to the impact of CPAP, sleep-related disorders, and sleep chronotype on a variety of diabetes-related end points. The study participants were recruited from the T2D services in multiple NHS trusts across England. The main exclusion criteria for the cohort study are as follows: T1D, eGFR < 15 mL/min/1.73 m², known OSA, active malignancy or chronic kidney disease from reasons other than diabetes, pregnancy, professional drivers, and a history of falling asleep whilst driving within last 2 years. The main exclusion criteria from the RCT were as follows: Apnoea-Hypopnoea Index < 10 and Epworth Sleepiness Score ≥ 11. Study participants were extensively phenotyped clinically and biochemically. The OSA diagnosis was based on multichannel portable device (ApneaLink Air^TM, Resmed).

DISCUSSION

The feasibility RCT will help us design the future RCT to assess the impact of CPAP on diabetes-related microvascular complications. The cohort study will generate preliminary data regarding the impact of sleep quality, duration, and chronotype on diabetes-related outcomes which could lead to further mechanistic and interventional studies.

TRIAL REGISTRATION

ISRCTN, ISRCTN12361838 . Registered 04 April 2018, Protocol version: v5.0 02.12.19.

Effects of Continuous Positive Airway Pressure Treatment for Obstructive Sleep Apnea-Hypopnea Syndrome on Corneal Morphological Characteristics

PURPOSE

To evaluate the effects of continuous positive airway pressure (CPAP) therapy on corneal endothelial morphometry and pachymetry in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS).

METHODS

This prospective, observational study included patients with OSAHS who were evaluated right before and after the commencement of CPAP treatment. Each patient underwent a detailed ophthalmologic examination and assessment of their corneal endothelium with a noncontact specular microscope (Tomey EM-3000; Tomey Corp). Endothelial cell density, coefficient of variation of cell area (CV), hexagonal cell appearance ratio (%Hex), and central corneal thickness were measured. The post-CPAP results were compared with the results of a control group. The differences in the corneal parameters between pre- and post-CPAP therapy of the OSAHS group were correlated with the pretreatment polysomnography results.

RESULTS

Twenty-seven distinct eyes of 27 patients recently diagnosed with OSAHS and 30 eyes of 30 healthy individuals were used for the statistical analysis. The mean age of patients with OSAHS was 54.2 ± 11.8 years, and after 9.6 months (range 3-18 mo) of good adherence to CPAP treatment, their CV values, indicating polymegathism, decreased from 41.7 ± 8.7 to 38.3 ± 5.8 (P = 0.04), whereas %Hex, indicating pleomorphism, increased from 45.8% ± 8.2% to 48.4% ± 6.6% (P = 0.008). Their post-CPAP corneal parameters did not differ significantly from those of the control group (P > 0.05). A significant positive correlation was observed between the decrease in CV and the duration of the treatment (Rs = 0.566, P = 0.002), as well as the pre-CPAP nonrapid eye movement (NREM) sleep percentage (Rs = 0.459, P = 0.02). A negative correlation was noted between the decrease in CV and the percentage of rapid eye movement (REM) sleep (Rs = -0.459, P = 0.02).

CONCLUSIONS

Better oxygenation during sleep, resulting from increased CPAP adherence, had a significant influence on corneal endothelium, providing an improvement in corneal polymegathism and pleomorphism, with a potential return of CV and %Hex to their normal values. Greater improvement in polymegathism was observed in patients with greater proportion of NREM sleep.

Toll-Like Receptor-4-Mediated Inflammation is Involved in Intermittent Hypoxia-Induced Lung Injury

PURPOSE

Intermittent hypoxia (IH) is a recognized risk factor for multiple organs damage, resulting in lung injury. Its pathophysiology is still poorly understood. Toll-like receptor 4 (TLR4) signaling plays a critical role in host immune response to invading pathogen and non-infectious tissue injury. The role of TLR4-mediated inflammation in IH-induced lung injury was investigated in this study.

METHODS

Lean adult male TLR4-deficient (TLR4^-/-) mice and their controls (C57BL/6 mice) were exposed to either IH (FiO₂ 6-8% for 25 s, 150 s/cycle, 8 h/day) or air (normoxic mice) for 6 weeks. Animals were sacrificed after 6-week exposure, and the lung tissues were harvested for morphological and inflammatory analyses. The expression of TLR4 and nuclear factor kappa-B (NF-κB) P65 were examined by real-time quantitative polymerase chain reaction and immunohistochemical method. Serum cytokine levels of interleukin (IL)-6 and tumor necrosis factor-alpha (TNF-α) were analyzed by enzyme-linked immunosorbent assay.

RESULTS

IH induced morphological and inflammation changes in the lung. IH for 6 weeks induced higher expression of TLR4 (C57BL/6-N vs C57BL/6-IH, P < 0.05) and resulted in higher release of TNF-α, IL-6 (P < 0.05), and NF-κB P65 (P < 0.05). These alterations were remitted by TLR4 deletion.

CONCLUSIONS

TLR4-mediated inflammation plays an important role in the development of IH-induced lung injury in mice, possibly through mechanisms involving nuclear factor-κB. Targeting TLR4/NF-κB pathway could represent a further therapeutic option for sleep apnea patients.

Evaluation of Serum and Plasma Interleukin-6 Levels in Obstructive Sleep Apnea Syndrome: A Meta-Analysis and Meta-Regression

Obstructive sleep apnea syndrome (OSAS) is considered a low-grade chronic inflammatory disease. Interleukin-6 (IL-6) is one of the most significant inflammatory markers and an excellent proxy for the inflammatory/immune system. The present meta-analysis and meta-regression aimed at comparing plasma and serum levels of IL-6 between individuals (children and adults) with OSAS and healthy controls. Four databases, PubMed/Medline, Scopus, Cochrane Library, and Web of Science, were comprehensively searched to retrieve articles published up to December, 2019, with no further restrictions. RevMan 5.3 software was used to calculate the crude mean difference (MD) and 95% confidence interval (CI). The results of funnel plots and meta-regression were analyzed by the CMA 2.0 software. Sixty-three studies (57 with adults; six with children) were included in the present meta-analysis. For adults, 37 studies reported significantly higher serum IL-6 levels and 20 reported significantly higher plasma IL-6 levels for those with OSAS than for healthy controls [pooled MD of 2.89 pg/ml (P < 0.00001) and pooled MD of 2.89 pg/ml (P < 0.00001), respectively]. The pooled analysis of serum and plasma IL-6 levels in children with OSAS compared with controls revealed that only the MD of plasma IL-6 levels was significant (MD = 0.84 pg/ml, P = 0.004). Results of the meta-regression showed that greater age was associated with higher serum IL-6 levels. Egger's test revealed a publication bias across the studies for serum and plasma IL-6 levels (P = 0.00044 and P = 0.01445, respectively). In summary, the meta-analysis and meta-regression confirmed that, compared to healthy controls, individuals with OSAS (children and adults) had higher serum/plasma IL-6 levels.

Sphingomyelins Prevent Propagation of Lipid Peroxidation-LC-MS/MS Evaluation of Inhibition Mechanisms

Free radical driven lipid peroxidation is a chain reaction which can lead to oxidative degradation of biological membranes. Propagation vs. termination rates of peroxidation in biological membranes are determined by a variety of factors including fatty acyl chain composition, presence of antioxidants, as well as biophysical properties of mono- or bilayers. Sphingomyelins (SMs), a class of sphingophospholipids, were previously described to inhibit lipid oxidation most probably via the formation of H-bond network within membranes. To address the “antioxidant” potential of SMs, we performed LC-MS/MS analysis of model SM/glycerophosphatidylcholine (PC) liposomes with different SM fraction after induction of radical driven lipid peroxidation. Increasing SM fraction led to a strong suppression of lipid peroxidation. Electrochemical oxidation of non-liposomal SMs eliminated the observed effect, indicating the importance of membrane structure for inhibition of peroxidation propagation. High resolution MS analysis of lipid peroxidation products (LPPs) observed in in vitro oxidized SM/PC liposomes allowed to identify and relatively quantify SM- and PC-derived LPPs. Moreover, mapping quantified LPPs to the known pathways of lipid peroxidation allowed to demonstrate significant decrease in mono-hydroxy(epoxy) LPPs relative to mono-keto derivatives in SM-rich liposomes. The results presented here illustrate an important property of SMs in biological membranes, acting as “biophysical antioxidant”. Furthermore, a ratio between mono-keto/mono-hydroxy(epoxy) oxidized species can be used as a marker of lipid peroxidation propagation in the presence of different antioxidants.

[Cardiac dysfunction and the obstructive sleep apnoea syndrome]

INTRODUCTION

Cardiac insufficiency affects nearly 2% of the population with increased morbidity/mortality despite advances in therapeutic management. The sleep apnoea syndrome (SAS) is a risk factor for, and cause of aggravation of, myocardial dysfunction.

BACKGROUND

SAS is found in 70% of patients with chronic cardiac failure, 65% of patients with refractory hypertension, 60% of patients with cerebro-vascular accidents and 50% of patients with atrial fibrillation. The associated cardiovascular mortality is multiplied by a factor of 2 to 3. The pathophysiological mechanisms are intermittent nocturnal hypoxia, variations in CO₂ levels, variations in intrathoracic pressure and repeated arrousals from sleep, concurrent with sympathetic hyperactivity, endothelial dysfunction and systemic inflammation.

CONCLUSIONS

SAS and cardiological management in patients presenting with myocardial dysfunction should be combined. It is necessary to pursue the scientific investigations with the aim of determining a precise care pathway and the respective places of each of the cardiological and pulmonary measures.

Is C-reactive protein elevated in obstructive sleep apnea? a systematic review and meta-analysis

Purpose: This study examined whether circulating C-reactive protein (CRP) is elevated in obstructive sleep apnoea (OSA) independent of the confounding effects of comorbidities, smoking, body mass index (BMI), age and gender. Methods: A systematic review of the literature was performed using PubMed, Embase and Cochrane databases from 1 January 1997 to 1 November 2017 using the key words obstructive sleep apnoea and C-Reactive protein to identify full text English language studies that compared CRP in adult non-smoking OSA participants without comorbidities and adult healthy non-smoking control participants matched for BMI, age and gender. Data from eligible studies were subjected to meta-analysis using RevMan version 5.3. Results: Five studies (219 OSA participants, 116 controls) met the selection criteria. The total standard mean difference for circulating high sensitivity CRP was 0.61 mg/dL higher in OSA participants than in control participants (confidence interval: 0.38 to 0.84, p < 0.00001), with low between-studies heterogeneity (df = 7, p = 0.16, I² = 33%) and minimal evidence of publication bias. Conclusions: CRP levels in non-smoking OSA participants without comorbidities were increased relative to levels in healthy matched non-smoking control participants, suggesting that pharyngeal or systemic inflammatory effects attributable to OSA may elevate CRP.

Association of continuous positive airway pressure with F2-isoprostanes in adults with obstructive sleep apnea: a meta-analysis

PURPOSE

Obstructive sleep apnea (OSA) is associated with increased F2-isoprostanes, a reliable standard biomarker of oxidative stress. Treatment with continuous positive airway pressure (CPAP) is effective for all degrees of OSA. However, it remains unknown whether treatment with CPAP will decrease F2-isoprostanes. A meta-analysis was conducted to determine the effect of CPAP treatment on F2-isoprostanes among patients with OSA.

METHODS

The PubMed, Embase, Web of Science, and Cochrane library were searched before September, 2018. Eight articles assessing indices of F2-isoprostanes from various body fluids were identified. Pooled standardized mean difference (SMD) and weighted mean difference (WMD) were appropriately calculated through fixed or random effects models after assessing between-study heterogeneity.

RESULTS

A total of 4 studies with 108 patients were pooled for exhaled breath condensate (EBC) F2-isoprostanes; 3 studies with 93 patients were pooled for serum or plasma F2-isoprostanes; and 3 studies with 102 patients were pooled for urinary F2-isoprostanes. A significant decrease of EBC F2-isoprostanes was observed after CPAP treatment (WMD = 2.652, 95% CI = 0.168 to 5.136, z = 2.09, p = 0.036), as well as serum or plasma F2-isoprostanes and urinary F2-isoprostanes (SMD = 1.072, 95% CI = 0.276 to 1.868, z = 2.64, p = 0.008 and WMD = 85.907, 95% CI = 50.443 to 121.372, z = 4.75, p = 0.000, respectively).

CONCLUSIONS

This meta-analysis suggested that CPAP therapy was associated with a significant decrease in F2-isoprostanes in patients with OSA.

Clinical usefulness of the body muscle-to-fat ratio for screening obstructive sleep apnea syndrome in patients with inadequately controlled type 2 diabetes mellitus

AIMS

To investigate whether body composition measures can be used for screening obstructive sleep apnea syndrome (OSAS) in patients with type 2 diabetes mellitus (T2DM) suspected of having OSAS.

METHODS

Subjects were 186 hospital inpatients with inadequately controlled T2DM. We measured the respiratory disturbance index (RDI) as an indicator of OSAS using a sheet-type breath detection monitor, defining OSAS as an RDI ≥ 19 events/hour. Elementary body composition was measured by bioelectrical impedance analysis using InBody770.

RESULTS

Simple logistic regression analysis identified body weight, body mass index (BMI), waist circumference, total body fat mass, body fat percentage, and body muscle-to-fat ratio (BMFR) as significantly associated with OSAS. The Nagelkerke R² test showed that the BMFR was the most suitable measure for screening OSAS. Multivariate logistic regression analysis demonstrated that BMFR was significantly and independently associated with OSAS. In receiver operating characteristic curve analysis, the area under the BMFR curve was 0.70 (P < 0.001), indicating that BMFR was significantly predictive of OSAS. Furthermore, BMFR was the most suitable measure for screening OSAS in a sub-group analysis of non-obese patients with relatively low BMI (<27.5 kg/m²).

CONCLUSIONS

In patients with T2DM, the BMFR is useful for screening OSAS in daily clinical practice.

Association of inflammatory genes in obstructive sleep apnea and non alcoholic fatty liver disease in Asian Indians residing in north India

Background

Previous studies have indicated that variants of the high sensitive C-reactive protein (CRP), Interleukin (IL)-6 and leptin receptor (LEPR) genes are associated with the presence of obstructive sleep apnea (OSA) but not in non-alcoholic fatty liver disease (NAFLD) in Asian Indians. The study was conducted to investigate the association of CRP rs1130864 (1444C/T), IL-6 rs1800795 (-174G/C) and LEPR rs1137101 (Q223R) genes with OSA and NAFLD in Asian Indians residing in North India.

Methods

240 overweight/ obese subjects [body mass index (BMI>23kg/m²)], 124 with OSA and with NAFLD (group 1), 47 with OSA without NAFLD (group 2), 44 without OSA and with NAFLD (group 3) and 25 without OSA and without NAFLD (group 4) were recruited in this study. The severity of NAFLD was based on abdomen liver ultrasound and of OSA on overnight polysomnography. Clinical details, anthropometry profile, body composition, biochemical parameters and inflammatory markers were measured. Polymerase chain reaction and restriction fragment length polymorphism of CRP, IL-6 and LEPR gene was performed. The associations of these polymorphisms with clinical, anthropometric and biochemical profiles were investigated. The genotypes were confirmed by DNA sequencing analysis.

Results

The C, T and R alleles of IL-6, CRP and LEPR genes was more frequent in OSA and NAFLD subjects and significantly correlated with higher protein levels. The prevalence of variant genotypes C/T of CRP, G/C of IL-6 and Q/R of LEPR genes was significantly higher in OSA subjects as compared to non OSA subjects. Further, C/C genotype of IL-6 (G/C), T/T of CRP (C/T) and RR genotype of LEPR (Q/R) was associated with significantly higher BMI, fat mass (kg), % body fat, waist circumference, serum triglycerides, total cholesterol, alkaline phosphate, aspartate transaminase and fasting insulin levels in OSA and NAFLD subjects. Using a multivariate analysis, the combined effect of three polymorphisms of CRP, IL-6 and LEPR gene variants on OSA and NAFLD risk was evaluated. Odds ratio for OSA and NAFLD with the combination of the three gene polymorphisms increased to 2.84 (95% CI: 1.08–6.54; p = 0.04) even when adjusted for sex, age and BMI.

Conclusion

Polymorphisms of pro-inflammatory cytokine genes were associated with increased risk of OSA and NAFLD in Asian Indians.

Strategies to decrease oxidative stress biomarker levels in human medical conditions: A meta-analysis on 8-iso-prostaglandin F2α

The widespread detection of elevated oxidative stress levels in many medical conditions has led to numerous efforts to design interventions to reduce its effects. Efforts have been wide-ranging, from dietary changes to administration of antioxidants, supplements, e.g., omega-3-fatty acids, and many medications. However, there is still no systemic assessment of the efficacy of treatments for oxidative stress reduction across a variety of medical conditions. The goal of this meta-analysis is, by combining multiple studies, to quantitate the change in the levels of the popular oxidative stress biomarker 8-iso-prostaglandin F2α (8-iso-PGF2α) after a variety of treatment strategies in human populations. Nearly 350 unique publications with 180 distinct strategies were included in the analysis. For each strategy, the difference between pre- or placebo and post-treatment levels calculated using Hedges' g value of effect. In general, administration of antibiotics, antihyperlipidemic agents, or changes in lifestyle (g = - 0.63, - 0.54, and 0.56) had the largest effect. Administration of supplements, antioxidants, or changes in diet (g = - 0.09, - 0.28, - 0.12) had small quantitative effects. To fully interpret the effectiveness of these treatments, comparisons to the increase in g value for each medical condition is required. For example, antioxidants in populations with coronary artery disease (CAD) reduce the 8-iso-PGF2α levels by g = - 0.34 ± 0.1, which is quantitatively considered a small effect. However, CAD populations, in comparison to healthy populations, have an increase in 8-iso-PGF2α levels by g = 0.38 ± 0.04; therefore, the overall reduction of 8-iso-PGF2α levels is ≈ 90% by this treatment in this specific medical condition. In conclusion, 8-iso-PGF2α levels can be reduced not only by antioxidants but by many other strategies. Not all strategies are equally effective at reducing 8-iso-PGF2α levels. In addition, the effectiveness of any strategy can be assessed only in relation to the medical condition investigated.

Which place of pharmacological approaches beyond continuous positive airway pressure to treat vascular disease related to obstructive sleep apnea?

Obstructive sleep apnea (OSA) is characterized by recurrent episodes of partial or complete upper airway obstruction, occurring during sleep, leading to chronic intermittent hypoxia (IH), which harms the cardiovascular system. OSA is associated with both functional and structural vascular alterations that contribute to an increased prevalence of fatal and non-fatal cardiovascular events. OSA is a heterogeneous disease with respect to the severity of hypoxia, the presence of daytime symptoms, obesity, and cardiovascular comorbidities. Various clusters of OSA phenotypes have been described leading to more highly personalized treatment. The aim of this review is to describe the various therapeutic strategies including continuous positive airway pressure (CPAP), oral appliances, surgery, weight loss, and especially pharmacological interventions that have been evaluated to reduce vascular alterations in both OSA patients and preclinical animal models. Conventional therapies, predominantly CPAP, have a limited impact on vascular alterations in the presence of co-morbidities. A better knowledge of pharmacological therapies targeting IH-induced vascular alterations will facilitate the use of combined therapies and is crucial for designing clinical trials in well-defined OSA phenotypes.

Elevated copper, hs C-reactive protein and dyslipidemia in drug free schizophrenia: Relation with psychopathology score

Inflammation, dyslipidemia and altered copper levels have been reported in several psychiatric disorders, including schizophrenia. However, their association with the severity of psychopathology in schizophrenia is yet to be established. The present study was designed to assess the serum levels of copper, highly sensitive C-reactive protein (hs-CRP) and lipid profile and to explore their association with psychopathology scores in schizophrenia. 40 cases and 40 controls were included in the study. Serum copper, hs-CRP and lipid profile were estimated in all the subjects. Disease severity was assessed using Positive and Negative Syndrome Scale (PANSS). Copper, hs-CRP, total cholesterol and LDL-Cholesterol were significantly increased and HDL-Cholesterol was significantly reduced in schizophrenia cases when compared with controls. Copper was positively correlated with hs-CRP (r=0.338, p=0.003). Total cholesterol was significantly correlated with PANSS total (r=0.452, p=0.003) and negative symptom scores (r=0.337, p=0.033). Triacylglycerol was positively correlated with general psychopathology symptom score (r=0.416, p=0.008). Copper and hs-CRP were increased and correlated well with each other in schizophrenia cases. Though total cholesterol and triacylglycerol showed positive association with severity of the psychopathology, copper and hs-CRP were not associated with the disease severity.

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

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

Effects of vitamin D supplementation as an adjuvant therapy in coronary artery disease patients

OBJECTIVES

Low vitamin D status has been shown to be associated with coronary artery disease. We planned to research the effects of vitamin D3 supplementation on the severity of coronary artery disease.

DESIGN

We investigated the effect of 0.5 μg vitamin D3 per day in a randomized, placebo-controlled, double-blind study in 90 stable coronary artery disease patients residing in Beijing. Coronary angiography was performed before and after 6 months of treatment that took place between January and June. 25-Hydroxyvitamin D was measured by chemiluminescence assay. Coronary artery disease severity was assessed by using the SYNTAX scores.

RESULTS

In vitamin D supplementation group, there was a significant increase in mean 25-hydroxyvitamin D levels from baseline (19.9 ± 9.8 ng/ml) to 6 months (35.8 ± 12.1 ng/ml; p < 0.001). At 6 months, the primary end point, a difference in the fall of SYNTAX score between the groups was -2.5 (95% CI -5.1 to -0.5; p < 0.001) under intention to treat analysis. Compared with the control group, patients treated with vitamin D3 also had greater decreases in high sensitivity C-reactive protein and renin-angiotensin system activity (p < 0.05).

CONCLUSIONS

Vitamin D supplementation has beneficial effects on coronary artery disease; it can be an adjuvant therapy for patients with coronary artery disease.

Reduction in oxidative stress biomarkers after adenotonsillectomy

OBJECTIVES

A number of otolaryngic conditions such as chronic tonsillitis, adenoid hypertrophy, and obstructive sleep apnea are associated with oxidative stress and elevated levels of serum oxidants. The objective of this study is to measure changes in urine biomarkers of oxidative stress in children after adenotonsillectomy.

METHODS

Twenty-two children with sleep disordered breathing (SDB) with tonsil and adenoid hypertrophy were enrolled prior to adenotonsillectomy. Controls consisted of 20 healthy children. Urine samples were collected from all patients. Levels of three urinary biomarkers for oxidative status, 8-hydroxy-2-deoxyguanosine (8-OxodG), F(2)-isoprostane, and malondialdehyde (MDA) were measured using high performance liquid chromatography. For the study group, urine samples were repeated 3 weeks after surgery.

RESULTS

In the study group, preoperative urinary levels of 8-OxodG were higher than in controls (p=0.015). Levels decreased after surgery compared to preoperative levels (p=0.002), and reached control levels (p=0.167) at 3 weeks. Levels of urinary F(2)-isoprostane were similar in both groups (p=0.252), but decreased significantly after surgery (p=0.020).

CONCLUSIONS

Children with SDB have elevated levels of urinary 8-OxodG, a marker of oxidative stress. Adenotonsillectomy results in decreased 8-OxodG and F(2)-isoprostane. These findings suggest that urine analysis may represent a valuable tool for the measurement of oxidative stress.

Is there an effect of obstructive sleep apnea syndrome on oxidative stress and inflammatory parameters in patients with craniofacial anomalies?

The aim of this study was to test the hypothesis that obstructive sleep apnea syndrome (OSAS) exhibits oxidative stress and inflammation in patients who have a congenital, craniofacial anomaly.This prospective, cross-sectional cohort study included ambulant sleep study data to asses OSAS in patients with syndromic craniosynostosis and Treacher Collins syndrome. Laboratory analyses were performed including malondialdehyde, tumor necrosis factor α (TNF-α), interleukin 6, and high-sensitivity C-reactive protein.Forty-eight patients were included; 11 were adults; 37 were children. The patients' body mass indexes were normal, with a median (SD) of 0.7 (-1.82 to 2.48) in children and 20.5 (15.2-29.4) in adults. Obstructive sleep apnea syndrome was diagnosed in 23 of 48 patients. It was mild (median obstructive apnea-hypopnea index [oAHI], 2.3; oxygenation-desaturation index [ODI], 0.9) in 16 patients and moderate/severe in 7 patients (median oAHI, 10.8; ODI, 5.0). Neither oxidative stress nor inflammation had a correlation with the oAHI and ODI. Only TNF-α was found significantly higher in both the OSAS and non-OSAS groups compared with the reference values (median, 15.1 pg/mL and 12.3 pg/mL versus 4.05 [0.0-8.1 pg/mL], P < 0.001 and P < 0.001, respectively).Based on our findings we conclude that (mainly mild) OSAS, oxidative stress, as well as high-sensitivity C-reactive protein and interleukin 6 levels are not abnormal in the day time in a population of nonobese patients with a craniofacial anomaly. The increased level of TNF-α cannot be explained by OSAS. Future research should focus on mapping chronobiologic changes for further interpretation of the results.

Investigation of the Plasma Nitrite Levels and Oxidant-Antioxidant Status in Obstructive Sleep Apnea Syndrome

INTRODUCTION

Obstructive sleep apnea (OSA) is one of the most prevalent sleep disorders. In the present study, we assessed the nitrite level, which is an indirect indicator of nitric oxide (NO), total oxidant status (TOS), total antioxidant status (TAS) and oxidative stress index (OSI), which may be associated with endotel dysfunction. We investigated the difference between the groups and the relationship among the severity of comorbid conditions.

METHODS

This study was conducted in 39 OSA patients confirmed by polysomnography and 40 healthy subjects (controls). The OSA group consisted of 10 women and 29 men and the control group consisted of 20 women and 20 men. Polysomnographic revealed mild OSA in two, moderate in 7 and severe in 30 cases. We measured plasma TAS, TOS and nitrite levels from venous blood. The OSI value was obtained by dividing the TOS and TAS values. Values were compared with the control group and between patient groups.

RESULTS

A high body mass index (BMI), cardiovasculer diseases (CVD) and the use of medication for co-morbid diseases were more prevalent in the OSA group (p=.001, p=.029 and p=.006, respectively). The median plasma TOS level and OSI in the obstructive sleep apnea syndrome (OUA) group were significantly higher than those in the control group (p=.001 and p=.001, respectively). The plasma median nitrite level and TAS did not show any significant difference between the OSA and the control groups. None of the parameters revealed a significant difference between severe and moderate OSA cases.

CONCLUSION

Our findings in the present study revealed that the oxidant-antioxidant balance shifted toward the oxidant side in OSA cases; however, the NO level did not change. These findings together may point out that some molecules other than NO may have a role in the pathophysiology of endothelial dysfunction and also in the disturbed oxidant-antioxidant balance in OSA.

OSAS-related inflammatory mechanisms of liver injury in nonalcoholic fatty liver disease

Obstructive sleep apnoea syndrome (OSAS) is a common sleep disorder, affecting over 4% of the general population, and is associated with metabolic syndrome and cardiovascular disease, independent of obesity and traditional risk factors. OSAS has been recently connected to nonalcoholic fatty liver disease (NAFLD), the most common chronic liver disease in the world, which can be found in 30% of the general adult population. Several studies suggest that the chronic intermittent hypoxia (CIH) of OSAS patients may per se trigger liver injury, inflammation, and fibrogenesis, promoting NAFLD development and the progression from steatosis to steatohepatitis, cirrhosis, and hepatocellular carcinoma. In NAFLD patients, liver disease may be caused by hypoxia both indirectly by promoting inflammation and insulin resistance and directly by enhancing proinflammatory cytokine production and metabolic dysregulation in liver cells. In this review, we focus on molecular mechanisms linking OSAS to NAFLD, including hypoxia inducible factor (HIF), nuclear factor kappa B (NF-κB), YKL-40, unfolded protein response, and hypoxic adipose tissue inflammation, which all could provide novel potential therapeutic approaches for the management of NAFLD patients with OSAS.

All-cause mortality from obstructive sleep apnea in male and female patients with and without continuous positive airway pressure treatment: a registry study with 10 years of follow-up

BACKGROUND

More information is needed about the effect on mortality of continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea (OSA), especially in women.

METHODS

We employed a historical cohort study design, using data from 25,389 patients with a diagnosis of OSA selected from the Danish National Patient Registry for the period 1999-2009. We used Cox proportional hazard function to evaluate the all-cause mortality from OSA in middle-aged and elderly males and females who were treated, or not, with CPAP.

RESULTS

Female OSA patients had a lower mortality than males, irrespective of whether they received CPAP treatment. CPAP treatment improved survival, as illustrated by the hazard ratio of 0.62 (P<0.001). This effect was dependent on gender: CPAP had no significant effect on 20- to 39-year-old males and females, but the overall mortality in this age group was small. Survival was increased by CPAP in 40- to 59-year-old and ≥60-year-old males, but no such effect was observed in females. Positive predictors of survival were young age, female gender, higher educational level, and low 3-year prior comorbidity as estimated by the Charlson Comorbidity Index. Negative predictors for survival were male gender, age ≥60 years, no CPAP treatment, prior comorbidity, and low educational level.

CONCLUSION

CPAP therapy is associated with reduced all-cause mortality in middle-aged and elderly males, but no significant effect was found in females.

Effects of 8 weeks of CPAP on lipid-based oxidative markers in obstructive sleep apnea: a randomized trial

Dyslipidaemia and increased oxidative stress have been reported in severe obstructive sleep apnea, and both may be related to the development of cardiovascular disease. We have previously shown in a randomized crossover study in patients with moderate to severe obstructive sleep apnea that therapeutic continuous positive airway pressure treatment for 8 weeks improved postprandial triglycerides and total cholesterol when compared with sham continuous positive airway pressure. From this study we have now compared the effect of 8 weeks of therapeutic continuous positive airway pressure and sham continuous positive airway pressure on oxidative lipid damage and plasma lipophilic antioxidant levels. Unesterified cholesterol, esterified unsaturated fatty acids (cholesteryl linoleate: C18:2; and cholesteryl arachidonate: C20:4; the major unsaturated and oxidizable lipids in low-density lipoproteins), their corresponding oxidized products [cholesteryl ester-derived lipid hydroperoxides and hydroxides (CE-O(O)H)] and antioxidant vitamin E were assessed at 20:30 hours before sleep, and at 06:00 and 08:30 hours after sleep. Amongst the 29 patients completing the study, three had incomplete or missing [CE-O(O)H] data. The mean apnea -hypopnoea index, age and body mass index were 38 per hour, 49 years and 32 kg m(-2) , respectively. No differences in lipid-based oxidative markers or lipophilic antioxidant levels were observed between the continuous positive airway pressure and sham continuous positive airway pressure arms at any of the three time-points [unesterified cholesterol 0.01 mm, P > 0.05; cholesteryl linoleate: C18:2 0.05 mm, P > 0.05; cholesteryl arachidonate: C20:4 0.02 mm, P = 0.05; CE-O(O)H 2.5 nm, P > 0.05; and lipid-soluble antioxidant vitamin E 0.03 μm, P > 0.05]. In this study, accumulating CE-O(O)H, a marker of lipid oxidation, does not appear to play a role in oxidative stress in obstructive sleep apnea.

Cardiovascular risk in patients with sleep apnoea with or without continuous positive airway pressure therapy: follow-up of 4.5 million Danish adults

BACKGROUND

The prognostic significance of age and continuous positive airway pressure (CPAP) therapy on cardiovascular disease in patients with sleep apnoea has not been assessed previously.

METHODS

Using nationwide databases, the entire Danish population was followed from 2000 until 2011. First-time sleep apnoea diagnoses and use of CPAP therapy were determined. Incidence rate ratios (IRRs) of ischaemic stroke and myocardial infarction (MI) were analysed using Poisson regression models.

RESULTS

Amongst 4.5 million individuals included in the study, 33 274 developed sleep apnoea (mean age 53, 79% men) of whom 44% received persistent CPAP therapy. Median time to initiation of CPAP therapy was 88 days (interquartile range 34-346). Patients with sleep apnoea had more comorbidities compared to the general population. Crude rates of MI and ischaemic stroke were increased for sleep apnoea patients (5.4 and 3.6 events per 1000 person-years compared to 4.0 and 3.0 in the general population, respectively). Relative to the general population, risk of MI [IRR 1.71, 95% confidence interval (CI) 1.57-1.86] and ischaemic stroke (IRR 1.50, 95% CI 1.35-1.66) was significantly increased in patients with sleep apnoea, in particular in patients younger than 50 years (IRR 2.12, 95% CI 1.64-2.74 and IRR 2.34, 95% CI 1.77-3.10, respectively). Subsequent CPAP therapy was not associated with altered prognosis.

CONCLUSIONS

Sleep apnoea is associated with increased risk of ischaemic stroke and MI, particularly in patients younger than 50 years of age. CPAP therapy was not associated with a reduced rate of stroke or MI.

Oxidative stress in children with obstructive sleep apnea syndrome

STUDY OBJECTIVES

Pediatric obstructive sleep apnea (OSA) is associated with cardiovascular consequences, including accelerated atherosclerosis and endothelial dysfunction. Increased lipid peroxidation, a marker of oxidative stress, has been identified in adults with OSA in a severity-dependent manner, with attenuation following treatment with continuous positive airway pressure therapy. Studies on oxidative stress in children with OSA are sparse and results are inconclusive. The objective of this study was to compare lipid peroxidation in children with OSA to non-OSA children.

METHODS

A prospective cross-sectional study of 26 children with polysomnography-confirmed OSA (oAHI ≥ 5/h TST) was conducted. Thirty age- and body mass index z-score-matched children with primary snoring (PS) served as a comparison group (oAHI ≤ 1/h TST). Fasting blood samples were obtained on the morning following the sleep study. Plasma oxidized low-density lipoprotein (oxLDL) concentrations were measured by enzyme-linked immunosorbent assay.

RESULTS

There were no group differences in patient characteristics and their lipid profiles. The mean oxLDL levels of the OSA group were significantly higher than those of the comparison group (53.1 ± 13.0 vs. 45.7 ± 10.0 U/L, respectively, p = 0.02). There was a significant positive correlation between plasma oxLDL and the apnea hypopnea index (r = 0.29, p = 0.03) and between oxLDL and the oxygen desaturation index (r = 0.51, p = 0.003), and a significant negative correlation between SpO2 nadir and oxLDL (r = -0.29, p = 0.03).

CONCLUSIONS

OSA in children is associated with increased lipid peroxidation in a severity-dependent manner. Lipid peroxidation levels correlate with the degree of intermittent hypoxia.

Obstructive sleep apnoea and diabetes: an update

PURPOSE OF REVIEW

The relationship between obstructive sleep apnoea (OSA) and dysglycaemia is well established. However, uncertainty remains as to the extent that obesity mediates this relationship. The impact of OSA treatment on glucose metabolism and the consequences of having OSA in patients with diabetes is unclear. This review aims to summarize the latest evidence regarding the links between OSA and dysglycaemia.

RECENT FINDINGS

OSA is associated with insulin resistance in lean individuals and predicts insulin resistance worsening longitudinally. Continuous positive airway pressure (CPAP) lowers insulin resistance in CPAP-compliant patients. OSA is associated with impaired β-cell function. In patients with type 2 diabetes (T2D), the association between OSA and glycosylated haemoglobin (HbA1c) is related to nocturnal hypoxaemia. Apnoea hypopnoea index (AHI) during rapid eye movement (REM) (not non-REM) sleep is associated with HbA1c. In-laboratory, supervised CPAP improves glycaemia. OSA is associated with and predicts the progression of some diabetic vascular complications. Intensive lifestyle intervention in patients with T2D improves OSA independent of weight loss.

SUMMARY

OSA is associated with insulin resistance and β-cell dysfunction independent of obesity. OSA is associated with HbA1c and vascular complications in patients with T2D. CPAP might improve insulin resistance and glycaemic measures. Lifestyle intervention has a significant impact on AHI in patients with T2D.

Vitamin D and nifedipine in the treatment of Chinese patients with grades I-II essential hypertension: a randomized placebo-controlled trial

OBJECTIVES

Low vitamin D status has been shown to be associated with hypertension. We planned to research the effect of vitamin D and nifedipine in the treatment of patients with essential hypertension.

METHODS

Patients with grades I-II essential hypertension were enrolled in this single-center, double-blind, placebo-controlled trial in Beijing. All patients received a conventional antihypertensive drug (nifedipine, 30 mg/d). One hundred and twenty-six patients were randomly assigned to receive vitamin D (n=63, 2000 IU/d) or a placebo (n=63) as an add-on to nifedipine, by the method of permutated block randomization. Ambulatory blood pressure monitoring was performed at baseline (month 0), at month 3 and at month 6.

RESULTS

In vitamin D supplementation group, there was a significant increase in mean 25-hydroxyvitamin D levels from baseline (19.4 ± 11.6 ng/ml) to 6 months (34.1 ± 12.2 ng/ml; p<0.001). At 6 months, the primary end points, a difference in the fall of 24-h mean blood pressure, between the groups was -6.2 mmHg (95% CI -11.2; -1.1) for systolic blood pressure (p<0.001) and -4.2 mmHg (95% CI -8.8; -0.3) for diastolic blood pressure (p<0.001) under intention to treat analysis. In patients with vitamin D <30 ng/ml at baseline (n=113), 24-h mean blood pressure decreased by 7.1/5.7 mmHg (p<0.001). Safety and tolerability were similar among the two groups.

CONCLUSIONS

Vitamin D supplementation can reduce blood pressure in patients with hypertension, it can be an adjuvant therapy for patients with grades I-II essential hypertension.

CLINICAL TRIAL REGISTRATION

This study was registered in the Chinese Clinical Trial Registry, it is available in Website: http://www.chictr.org/cn/;

REGISTRATION NUMBER

ChiCTR-ONC-13003840.

Obstructive Sleep Apnoea and Type 2 Diabetes

With the growing prevalence of obesity, the burden of type 2 diabetes is increasing. Obstructive sleep apnoea (OSA) is a very common medical condition that is associated with increased risk of cardiovascular disease and mortality. Obesity is a common risk factor for OSA and type 2 diabetes and hence it is not surprising that OSA and type 2 diabetes are interlinked. OSA has been shown to be an independent risk factor for the development of incident pre-diabetes/type 2 diabetes. OSA is also associated with worse glycaemic control and vascular disease in patients with type 2 diabetes. However, evidence for the benefits of OSA treatment in patients with type 2 diabetes is still lacking. The aim of this article is to provide an overview of OSA, the relationships between OSA and dysglycaemia and the impact of OSA in patients with type 2 diabetes, highlighting recent advances in the field.

Urinary concentration of 8-isoprostane as marker of severity of pediatric OSAS

BACKGROUND

F2-isoprostanes are considered to be a reliable standard biomarker of oxidative stress in vivo because they are not influenced by the intake of lipids in the diet, and they are chemically stable molecules and easily detected. This study aimed to test the hypothesis that 8-isoprostane level is a useful marker to valuate the severity of pediatric obstructive sleep apnea (OSA).

METHODS

Sixty-five children with sleep-disordered breathing (SDB) (mean age 5.9±2.0 years; 63.1% males) were recruited. The urine sample for the measurement of 8-isoprostane was collected the morning after the polysomnographic recording. Children were divided into two groups according to their apnea-hypopnea index (AHI).

RESULTS

Urinary 8-isoprostane levels positively correlated with the sleep clinical record score (r=0.38, p=0.002) and AHI (r=0.24, p=0.05) and negatively correlated with age (r=-0.36, p=0.003) and body surface area (r=-0.38, p=0.002). Urinary 8-isoprostane levels were significantly higher in the group with AHI of ≥5 events (ev)/h than in the group with AHI of <5 ev/h (p<0.01).

CONCLUSIONS

Urinary 8-isoprostane may be used as a specific inflammatory marker to predict the severity of OSA; this method has the advantage of being noninvasive and easy to use in both compliant and noncompliant children.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Obstructive sleep apnea and endothelial progenitor cells

BACKGROUND

Obstructive sleep apnea (OSA) occurs in 4% of middle-aged men and 2% of middle-aged women in the general population, and the prevalence is even higher in specific patient groups. OSA is an independent risk factor for a variety of cardiovascular diseases. Endothelial injury could be the pivotal determinant in the development of cardiovascular pathology in OSA. Endothelial damage ultimately represents a dynamic balance between the magnitude of injury and the capacity for repair. Bone marrow-derived endothelial progenitor cells (EPCs) within adult peripheral blood present a possible means of vascular maintenance that could home to sites of injury and restore endothelial integrity and normal function.

METHODS

We summarized pathogenetic mechanisms of OSA and searched for available studies on numbers and functions of EPCs in patients with OSA to explore the potential links between the numbers and functions of EPCs and OSA. In particular, we tried to elucidate the molecular mechanisms of the effects of OSA on EPCs.

CONCLUSION

Intermittent hypoxia cycles and sleep fragmentation are major pathophysiologic characters of OSA. Intermittent hypoxia acts as a trigger of oxidative stress, systemic inflammation, and sympathetic activation. Sleep fragmentation is associated with a burst of sympathetic activation and systemic inflammation. In most studies, a reduction in circulating EPCs has emerged. The possible mechanisms underlying the decrease in the number or function of EPCs include prolonged inflammation response, oxidative stress, increased sympathetic activation, physiological adaptive responses of tissue to hypoxia, reduced EPC mobilization, EPC apoptosis, and functional impairment in untreated OSA. Continuous positive airway pressure (CPAP) therapy for OSA affects the mobilization, apoptosis, and function of EPCs through preventing intermittent hypoxia episodes, improving sleep quality, and reducing systemic inflammation, oxidative stress levels, and sympathetic overactivation. To improve CPAP adherence, the medical staff should pay attention to making the titration trial a comfortable first CPAP experience for the patients; for example, using the most appropriate ventilators or proper humidification. It is also important to give the patients education and support about CPAP use in the follow-up, especially in the early stage of the treatment.

The effects of low vitamin D on coronary artery disease

PURPOSE

Coronary Artery Disease (CAD) remains a major cause of morbidity and mortality in the world. Low vitamin D status has been shown to be associated with increased risk of developing cardiovascular disease, hypertension and obesity. We planned to research the association between low vitamin D status and the severity of CAD.

PROCEDURES

A total of 348 consecutive patients undergoing coronary angiography for evaluation of CAD were included in this study. 25-Hydroxyvitamin D [25(OH)D] was measured by chemiluminescence assay. CAD severity was assessed by using the SYNTAX scores. The data presented are the mean levels/values and standard deviation.

FINDINGS

The serum 25(OH)D level of CAD patients was 18.2 ± 10.6 ng/ml. The SYNTAX scores were 27.8 ± 8.5. In a multivariate linear regression analysis (adjusted for age, high-sensitivity C-reactive protein, SYNTAX score, parathyroid hormone, body mass index, haemoglobin and creatinine), the serum 25(OH)D level showed a negative correlation with SYNTAX score and high-sensitivity C-reactive protein (hsCRP) level. Logistic regression analysis identified 25(OH)D as an independent factor related to high SYNTAX scores. Patients whose vitamin D levels were in the lowest 25(OH)D category (<20 ng/ml) were more often in the high SYNTAX scores group, with their incidence about two-fold higher than those in the highest 25(OH)D category (>30 ng/ml).

CONCLUSION

Low vitamin D is associated with the severity of coronary artery stenosis.