Circulating Sex-Specific Markers of Plaque Instability in Women and Men With Severe Carotid Atherosclerosis.

BACKGROUND: Sex-specific differences in plaque composition and instability underscore the need to explore circulating markers for better prediction of high-risk plaques. This cross-sectional study aims to (1) investigate differences in lipid, immune, and adipokine circulating profiles between men and women with stable versus unstable plaques and (2) identify circulating markers that can better classify men and women according to plaque instability. METHODS: Preoperative blood samples and plaque specimens were collected from consecutive men and women with carotid artery stenosis ≥50% and who underwent a carotid endarterectomy between 2009 and 2018. Adipokine, lipid, and immune profiling was conducted. Plaque stability was determined by gold-standard histological classifications. Statistical analyses, including χ2, ANOVA, Kruskal-Wallis, and logistic regression, assessed differences in plaque features and blood parameters between men and women with stable and unstable plaques. RESULTS: Of 470 recruited patients (aged 70.8±9.2 years), the final study analyses included 317 men and 143 women (aged 71.0±9.0 years). Men exhibited more unstable plaques (P<0.001), characterized by increased plaque hemorrhage, larger lipid core, and inflammation (P<0.001), along with less favorable circulating profiles. Antagonistic interactions between sex and white blood cell (WBC) counts, basophil-to-WBC ratio, and platelet counts influenced plaque instability. In men, low WBC counts, high monocyte-to-WBC ratio, low basophil-to-WBC ratio, and high LDL-C (low-density lipoprotein cholesterol) levels were associated with greater plaque instability (odds ratio, 0.827 [95% CI, 0.713-0.926], 1.158 [95% CI, 1.027-1.305], 0.495 [95% CI, 0.281-0.871], and 1.564 [95% CI, 1.001-2.443], respectively) and more unstable features (ie, inflammation, foam cells, and neovascularization). In women, a high basophil-to-WBC ratio was associated with greater plaque instability (3.142 [95% CI, 1.220-8.093]), hemorrhage, and thrombosis, while a high molecular weight-to-total adiponectin ratio was associated with decreased instability (0.014 [95% CI, 0.000-0.646]) and inflammation. CONCLUSIONS: Our findings demonstrated sex-specific differences, with women displaying more stable plaque phenotypes and favorable circulating profiles compared with men. This proof-of-concept study was also designed as the key first step in exploring novel sex-specific associations between circulating lipid, immune, and adipokine profiles and carotid plaque instability.

Relationship between circulating adipokines and cholesterol efflux in subjects with severe carotid atherosclerosis.

AIMS: Cholesterol efflux capacity (CEC) as a measure of high-density lipoprotein functionality is independently and inversely associated with increased risk of cardiovascular events and mortality, and advanced plaque morphology. Adipokines, adipose tissue-derived factors, can influence systemic lipoprotein metabolism, and participate in the regulation of vascular function and inflammation. We aimed to investigate the association between CEC and circulating adipokine levels (anti-inflammatory adiponectin, and pro-inflammatory chemerin and resistin) in subjects with severe carotid atherosclerotic disease and evaluate its impact on post-surgical outcomes. METHODS AND RESULTS: This is a cross-sectional study with a 5-year follow-up component. Consecutive patients with severe carotid atherosclerosis scheduled for a carotid endarterectomy were recruited from hospital-based centres in Montreal, Canada (n = 285). Fasting blood samples were collected pre-operatively and used to measure plasma total and high-molecular weight (HMW) adiponectin, chemerin, and resistin, and to perform cholesterol efflux assays in J774 macrophage-like cells. Five-year post-surgery outcomes were obtained through medical chart review. Subjects had a mean age of 70.1 ± 9.4, were 67.0 % male, had various comorbidities (hypercholesterolemia [85.3 %], hypertension [83.5 %], type 2 diabetes [34.5 %], coronary artery disease [38.6 %]), and previously experienced cerebrovascular symptomatology (77.9 %). CEC was independently and positively associated with total and HMW adiponectin levels (ß [95 % confidence interval]; 0.216 [0.134-0.298] and 0.107 [0.037-0.176], respectively) but not with chemerin or resistin. Total adiponectin had the greatest association accounting for 8.3 % of the variance in CEC. Interaction regression models demonstrated a significant interaction between adiponectin and chemerin in increasing CEC. Notably, with each unit increase in CEC there was a 93.9 % decrease in the odds of having an ischemic cerebrovascular event 5 years post-surgery (0.061 [0.007-0.561]). CONCLUSIONS: Our findings demonstrated circulating adiponectin to have a strong association with increased CEC in subjects with severe carotid atherosclerosis and high CEC to be associated with more favourable post-surgical outcomes. These findings reflect the importance of adipose tissue health in influencing CEC levels and atherosclerotic cardiovascular disease risk.

An LC-MS/MS Methodological Framework for Steroid Hormone Measurement from Human Serum.

Estrogens and androgens are important regulators of sexual development and physiological processes in men and women, acting on numerous organs throughout the body. Moreover, they can contribute to a variety of pathologies, including osteoporosis, cancer, and cardiovascular and neurologic diseases. Analysis of estrogens and androgens in biological samples has been commonly performed using immunoassays for many years. However, these assays are suboptimal, as there is cross-reactivity with similar analytes, and they have moderate specificity and sensitivity. Thus, there is a clinical need to develop highly sensitive and specific methods for the accurate measurement of estrogen and androgen concentrations. Herein, we describe the development of three liquid chromatography coupled tandem mass spectrometry-based methods that incorporate the use of a Triple Quadrupole Mass Spectrometer for quantitative measurement of endogenous concentrations of various steroid hormones in human serum samples: (1) the simultaneous measurement of testosterone, androstenedione, and cortisol, (2) dehydroepiandrosterone (DHEA), and (3) 17ß-estradiol (E2). The use of derivatizing reagents, Girard's reagent P and dansyl chloride, allowed for significant gains in sensitivity in the analysis of DHEA and E2, respectively, relative to the underivatized analyte. These procedures proved efficient and adequately sensitive for steroid hormone analysis in extracted patient sera samples from older men and postmenopausal women, providing reliable data down to low nanogram/ml and sub-nanogram/ml levels. Moreover, utilizing the combination of highly specific mass transitions associated with these analytes and their respective internal deuterated standards provided a high degree of specificity to the identity of these hormones.

Bioactive Scaffolds in Stem Cell-Based Therapies for Myocardial Infarction: a Systematic Review and Meta-Analysis of Preclinical Trials.

The use of bioactive scaffolds in conjunction with stem cell therapies for cardiac repair after a myocardial infarction shows significant promise for clinical translation. We performed a systematic review and meta-analysis of preclinical trials that investigated the use of bioactive scaffolds to support stem cell-aided cardiac regeneration, in comparison to stem cell treatment alone. Cochrane Library, Medline, Embase, PubMed, Scopus, Web of Science, and grey literature were searched through April 23, 2020 and 60 articles were included in the final analysis. The overall effect size observed in scaffold and stem cell-treated small animals compared to stem cell-treated controls for ejection fraction (EF) was 7.98 [95% confidence interval (CI): 6.36, 9.59] and for fractional shortening (FS) was 5.50 [95% CI: 4.35, 6.65] in small animal models. The largest improvements in EF and FS were observed when hydrogels were used (MD = 8.45 [95% CI: 6.46, 10.45] and MD = 5.76 [95% CI: 4.46, 7.05], respectively). Subgroup analysis revealed that cardiac progenitor cells had the largest effect size for FS, and was significant from pluripotent, mesenchymal and endothelial stem cell types. In large animal studies, the overall improvement of EF favoured the use of stem cell-embedded scaffolds compared to direct injection of cells (MD = 10.49 [95% CI: 6.30, 14.67]). Significant publication bias was present in the small animal trials for EF and FS. This study supports the use of bioactive scaffolds to aid in stem cell-based cardiac regeneration. Hydrogels should be further investigated in larger animal models for clinical translation.

Importance of sex and gender in ischaemic stroke and carotid atherosclerotic disease.

Stroke is a leading cause of death and disability worldwide. Women are disproportionately affected by stroke, exhibiting higher mortality and disability rates post-stroke than men. Clinical stroke research has historically included mostly men and studies were not properly designed to perform sex- and gender-based analyses, leading to under-appreciation of differences between men and women in stroke presentation, outcomes, and response to treatment. Reasons for these differences are likely multifactorial; some are due to gender-related factors (i.e. decreased social support, lack of stroke awareness), yet others result from biological differences between sexes. Unlike men, women often present with 'atypical' stroke symptoms. Lack of awareness of 'atypical' presentation has led to delays in hospital arrival, diagnosis, and treatment of women. Differences also extend to carotid atherosclerotic disease, a cause of stroke, where plaques isolated from women are undeniably different in morphology/composition compared to men. As a result, women may require different treatment than men, as evidenced by the fact that they derive less benefit from carotid revascularization than men but more benefit from medical management. Despite this, women are less likely than men to receive medical therapy for cardiovascular risk factor management. This review focuses on the importance of sex and gender in ischaemic stroke and carotid atherosclerotic disease, summarizing the current evidence with respect to (i) stroke incidence, mortality, awareness, and outcomes, (ii) carotid plaque prevalence, morphology and composition, and gene connectivity, (iii) the role of sex hormones and sex chromosomes in atherosclerosis and ischaemic stroke risk, and (iv) carotid disease management.

Expression of Resistin, Chemerin, and Chemerin's Receptor in the Unstable Carotid Atherosclerotic Plaque.

Background and Purpose: Unstable carotid plaques are a common cause of ischemic strokes. Identifying markers that reflect/contribute to plaque instability has become a prominent focus in cardiovascular research. The adipokines, resistin and chemerin, and ChemR23 (chemerin receptor), may play a role in carotid atherosclerosis, making them potential candidates to assess plaque instability. However, the expression and interrelationship of resistin and chemerin (and ChemR23) protein and mRNA within the carotid atherosclerotic plaque remains elusive. Thus, we investigated herein, the association between plaque mRNA and protein expression of resistin and chemerin (and ChemR23) and carotid plaque instability in humans, and whether sex differences exist in the relationship between these adipokines and plaque instability. Methods: Human carotid plaques were processed for immunohistochemical/mRNA analysis of resistin, chemerin, and ChemR23. Plaque instability was assessed by gold-standard histological classifications. A semi-quantitative scoring system was used to determine the intensity of adipokine expression on macrophages/foam cells, as well as the percentage of inflammatory cells stained positive. Plaque adipokine protein expression was also digitally quantified and mRNA expression was assessed by qRT-PCR. Results: Resistin and chemerin mRNA expression was 80% and 32% lower, respectively, in unstable versus stable plaques (P<0.05), while no difference in ChemR23 mRNA expression was observed. In contrast, greater resistin staining intensity and percentage of cells stained positive were detected in unstable versus stable plaques (P<0.01). Similarly, chemerin and ChemR23 staining intensity and percentage of cells stained were positively associated with plaque instability (P<0.05). No strong sex-specific relationship was observed between adipokines and plaque instability. Conclusions: This study examined the relationship between resistin, chemerin, and ChemR23, and carotid plaque instability, with a specific analysis at the plaque level. We reported a positive association between plaque instability and protein levels of resistin, chemerin, and ChemR23 but a negative association with resistin and chemerin mRNA expression. This suggests these adipokines exert proinflammatory roles in the process of carotid atherosclerosis and may be regulated via a negative feedback regulatory mechanism.

Sex differences in the efficacy of antihypertensive treatment in preventing cardiovascular outcomes and reducing blood pressure: protocol for a systematic review and meta-analysis.

INTRODUCTION: Hypertension is a leading cause of mortality worldwide and its prevalence is expected to rise over the next decade. Sex differences exist in the epidemiology and pathophysiology of hypertension. It is well established that antihypertensive treatment can significantly reduce the risk for stroke and other cardiovascular disease events. However, it remains unclear whether this effect is dependent on sex. In this protocol, we outlined a systematic review and meta-analysis to evaluate the effects of antihypertensive therapy in (1) reducing blood pressure and (2) preventing cardiovascular morbidity and mortality outcomes for each sex separately. METHODS AND ANALYSIS: The following electronic databases will be searched: Medline, Embase, The Cochrane Library, PubMed, Cumulative Index of Nursing and Allied Health Literature Plus, Web of Science, grey literature (Google Scholar) and several trial registries. Search strategies will be designed to identify human adult (≥18) randomised (and non-randomised) controlled trials, prospective and retrospective cohort studies, and case-control studies concerning 'sex-specific differences associated with the efficacy of antihypertensive treatment'. A preliminary search strategy was developed for Medline (1946-16 September 2019). Two investigators will independently review each article included in the final analysis. Primary outcomes investigated are cardiovascular morbidity and mortality and systolic and diastolic blood pressure. Pooled analyses will be conducted using the random-effects model. Publication bias will be assessed by visual inspection of funnel plots and by Begg's and Egger's statistical tests. Between-studies heterogeneity will be measured using the I2 test (p<0.10). Sources of heterogeneity will be explored by sensitivity, subgroup and metaregression analyses. ETHICS AND DISSEMINATION: This is the first meta-analysis that will comprehensively compare the efficacy of antihypertensive treatment regimens between men and women. Findings will be shared through scientific conferences and societies, social media and consumer advocacy groups. Results will be used to inform the current guidelines for management of hypertension in men and women by demonstrating the importance of implementing sex-specific recommendations. Ethical considerations are not applicable for this protocol.

Intensive Statin Therapy Compromises the Adiponectin-AdipoR Pathway in the Human Monocyte-Macrophage Lineage.

Background and Purpose- Statins are widely used for cardiovascular disease prevention through cholesterol-lowering and anti-inflammatory effects. Adiponectin, an anti-inflammatory adipokine, acts via two receptors, AdipoR1 and AdipoR2, to exert atheroprotective effects on the vasculature. We investigated whether statins can modulate the adiponectin-AdipoR pathway in the human monocyte-macrophage lineage. Methods- Monocytes were isolated from the whole blood of patients with severe carotid atherosclerosis (cross-sectional study) or from patients with cardiovascular risk factors (longitudinal study) and assessed for AdipoR1 and AdipoR2 gene expression using quantitative real-time polymerase chain reaction. In vitro, THP-1 (Tamm-Horsfall protein 1) macrophages were treated with increasing atorvastatin or rosuvastatin doses for 24- or 72-hours to determine the effect of statins on AdipoR expression and activity. Macrophage cytokine secretion (IL [interleukin]-1ß, IL-10, IL-6, and TNF [tumor necrosis factor]-α) was assessed by electrochemiluminescence. Results- AdipoR1 and AdipoR2 mRNA expression on circulating monocytes from patients with carotid atherosclerosis, was significantly lower by 1.36- and 1.17-fold, respectively, in statin users versus statin-naïve patients. Specifically, patients on high doses of atorvastatin (40-80 mg) or rosuvastatin (20-40 mg) had significantly lower AdipoR gene expression versus statin-naïve patients. Similarly, in the longitudinal in vivo study, longer atorvastatin/rosuvastatin treatment (≥5 months) in patients with cardiovascular risk factors resulted in lower AdipoR gene expression on circulating monocytes versus prestatin levels. In vitro, higher statin doses and longer exposure resulted in a greater decrease in AdipoR mRNA expression and greater macrophage secretion of pro-inflammatory cytokines, IL-1ß, IL-6, and TNF-α. High statin doses also reduced adiponectin's capacity to suppress intracellular cholesteryl ester levels in oxLDL (oxidized LDL)-loaded macrophages, with rosuvastatin exhibiting higher potency than atorvastatin. Conclusions- Our in vivo and in vitro studies identified a novel pleiotropic property of statins in modulating the adiponectin-AdipoR pathway in the human monocyte-macrophage lineage, where intensive statin therapy compromised the expression and function of adiponectin and its receptors.

New Quantitative Digital Image Analysis Method of Histological Features of Carotid Atherosclerotic Plaques.

OBJECTIVE: Atherosclerosis and its thrombotic complications are major causes of morbidity and mortality worldwide. Plaque stability assessment is considered to be important for both clinical and fundamental applications. The current gold standard method to investigate plaque stability is performed by histological assessment of plaque features using semi-quantitative classifications. However, these assessments can be limited by subjectivity and variability. Thus, the aim was to develop a new digital image analysis method to measure quantitatively individual plaque features that is more precise than existing semi-quantitative methods. METHODS: A quantitative method was developed using Image Pro Primer software. Carotid plaque specimens were obtained from patients who underwent carotid endarterectomy and categorised according to stability (definitely stable, probably stable, probably unstable, definitely unstable) based on the gold standard semi-quantitative method that assesses 10 histological plaque features. Using the new quantitative method, plaque features (n = 15) from each stability grade were then analysed by two independent raters. For the semi-quantitative analysis, quadratic weighted Cohen's kappa was used to test intra- and inter-rater reliability, while for the quantitative analysis, intraclass correlation coefficients (ICCs) were assessed. RESULTS: Intra-rater reliability demonstrated almost perfect agreement between both methods (Cohen's kappa range 0.831-0.969, ICC range 0.848-1.000). However, inter-rater reliability demonstrated mainly fair to moderate agreement (Cohen's kappa range 0.341-0.778) for the semi-quantitative analysis, while the digital image analysis method performed most optimally regarding reproducibility, yielding high ICCs close to 1 (ICC range 0.816-0.999). Using quantitative measurements, a statistically significant proportion of the individual plaque features (p < .05) were re-classified from one grade to another (shift by one) under the semi-quantitative classification. CONCLUSION: A new quantitative digital image analysis was developed for the accurate assessment of histological plaque features, which demonstrated higher precision than the gold standard semi-quantitative methods, as measured by between and within rater analysis. Moreover, quantitative image analysis of histological plaque features provided more detailed insight into plaque morphology and composition.

The role of adiponectin in cholesterol efflux and HDL biogenesis and metabolism.

Cholesterol efflux is the initial step in the reverse cholesterol transport pathway by which excess cholesterol in peripheral cells is exported and subsequently packaged into high-density lipoprotein (HDL) particles. Adiponectin is the most abundantly secreted adipokine that possesses anti-inflammatory and vasculoprotective properties via interaction with transmembrane receptors, AdipoR1 and AdipoR2. Evidence suggests that low levels of adiponectin may be a useful marker for atherosclerotic disease. A proposed anti-atherogenic mechanism of adiponectin involves its ability to promote cholesterol efflux. We performed a systematic review of the role of adiponectin in cholesterol efflux and HDL biogenesis, and of the proteins and receptors believed to be implicated in this process. Nineteen eligible studies (7 clinical, 11 fundamental, 1 clinical + fundamental) were identified through Ovid Medline, Ovid Embase, and Pubmed, that support the notion that adiponectin plays a key role in promoting ABCA1-dependent cholesterol efflux and in modulating HDL biogenesis via activation of the PPAR-γ/LXR-α signalling pathways in macrophages. AdipoR1 and AdipoR2 are suggested to also be implicated in this process, however the data are conflicting/insufficient to establish any firm conclusions. Once the exact mechanisms are unravelled, adiponectin may be critical in defining future treatment strategies directed towards increasing HDL functionality and ultimately reducing atherosclerotic disease.

Bioactive scaffolds in stem-cell-based therapies for cardiac repair: protocol for a meta-analysis of randomized controlled preclinical trials in animal myocardial infarction models.

BACKGROUND: Acute myocardial infarction (MI) remains one of the leading causes of death worldwide with no curative therapy available. Stem cell therapies have been gaining interest as a means to repair the cardiac tissue after MI and prevent the onset of heart failure. Many in vivo reports suggest that the use of stem cells is promising, yet clinical trials suggest that the cells fail to integrate into the native tissue, resulting in limited improvements in cardiac function and repair. To battle this limitation, the combination of using stem cells embedded in a bioactive scaffold that promotes cell retention is growing in interest. Yet, a systematic review of the literature on the use of stem cells embedded in bioactive scaffolds for cardiac repair has not yet been performed. In this protocol, we outline a systematic review and meta-analysis of preclinical trials in animal MI models that utilize stem cell-embedded scaffolds for cardiac repair and compare their effects to stem cell-treated animals without the use of a scaffold. METHODS/DESIGN: We will search the following electronic databases: Cochrane Library, MEDLINE, Embase, PubMed, Scopus and Web of Science, and gray literature: Canadian Agency for Drugs and Technologies in Health and Google Scholar. We will only include randomly controlled preclinical trials that have directly investigated the effects of stem cells embedded in a scaffold for cardiac repair in an animal MI model. Two investigators will independently review each article included in the final analysis. The primary endpoint that will be investigated is left ventricular ejection fraction. Secondary endpoints will include infarct size, end systolic volume, end diastolic volume, fractional shortening and left ventricular wall thickness. Pooled analyses will be conducted using the DerSimonian-Laird random effects and Mantel-Haenszel fixed-effect models. Between-studies heterogeneity will be quantified and determined using the Tau2 and I2 statistics. Publication bias will be assessed using visual inspection of funnel plots and complemented by Begg's and Egger's statistical tests. Possible sources of heterogeneity will be assessed using subgroup-meta analysis and meta-regression. DISCUSSION: To date, the use of scaffolds in myocardial repair has not yet been systematically reviewed. The results of this meta-analysis will aid in determining the efficacy of stem cell-embedded scaffolds for cardiac repair and help bring this therapy to the clinic.

Decreased Adiponectin-Mediated Signaling Through the AdipoR2 Pathway Is Associated With Carotid Plaque Instability.

BACKGROUND AND PURPOSE: Adiponectin, the most abundantly secreted anti-inflammatory adipokine, protects against all stages of atherosclerotic plaque formation by acting on its receptors, AdipoR1 (adiponectin receptor 1) and AdipoR2 (adiponectin receptor 2). Through binding of AdipoR1, adiponectin leads to the activation of the AMPK (adenosine monophosphate-activated protein kinase) pathway, whereas stimulation of PPAR-α (peroxisome proliferator-activated receptor-α) is attributed to the binding of AdipoR2. However, the role of adiponectin and its receptors in plaque instability remains to be characterized. Thus, we aimed to investigate whether the adiponectin-AdipoR pathway is associated with carotid atherosclerotic plaque instability. METHODS: The instability of plaque specimens obtained from patients who underwent a carotid endarterectomy (n=143) was assessed using gold standard histological classifications. RESULTS: Using immunohistochemistry, we showed that adiponectin and AdipoR1/AdipoR2 are expressed in human carotid plaques and that their expression was localized most abundantly in areas of macrophage and foam cell accumulation. Unstable plaques expressed more adiponectin protein (Western blot, P<0.05) and less AdipoR2 mRNA (2.11-fold decrease, P<0.05) than stable plaques, whereas AdipoR1 expression remained similar between stable and unstable plaques. Beyond AdipoR1/AdipoR2 expression, a graded decrease in PPAR-α protein levels was observed in relation to carotid plaque instability (P<0.001), whereas AMPK phosphorylation was increased (P<0.05). Our in vitro model of plaque instability, involving the induction of foam cells from human THP-1 (Tamm-Horsfall protein 1) macrophages treated with acetylated low-density lipoprotein, supported our in vivo conclusions. CONCLUSIONS: An overall abundance of adiponectin with a decrease in AdipoR2 expression and activity was observed in unstable plaques, suggesting that reduced signaling through the AdipoR2 pathway, and not through AdipoR1, may contribute to plaque instability.

Circulating adiponectin levels in relation to carotid atherosclerotic plaque presence, ischemic stroke risk, and mortality: A systematic review and meta-analyses.

BACKGROUND: Low circulating levels of adiponectin, an anti-inflammatory and vasculoprotective adipokine, are associated with obesity, type 2 diabetes, and atherosclerotic disease. Presence of unstable plaques in the carotid artery is a known etiological factor causing ischemic strokes. Herein, we systematically reviewed the association between circulating adiponectin and progression of carotid atherosclerotic disease, particularly evaluating the occurrence of (1) carotid atherosclerotic plaques, (2) ischemic stroke, and (3) mortality in subjects who suffered a previous ischemic stroke. METHODS: Medline, Embase, Biosis, Scopus, Web of Science, and Pubmed were searched for published studies and conference abstracts. The effect size and 95% confidence intervals (CIs) of the individual studies were pooled using fixed-effect or random-effect models. The quality of the eligible studies was evaluated using the Newcastle-Ottawa quality assessment scale. Sensitivity, subgroup, and meta-regression analyses were performed to address the impact of various risk factors on the association between adiponectin and ischemic stroke risk. RESULTS: Twelve studies fulfilled the inclusion criteria for 3 independent meta-analyses. The association of increasing circulating adiponectin levels (5µg/mL-increment) with presence of carotid plaque was not conclusive (n=327; OR: 1.07; 95% CI: 0.85-1.35; 2 studies), whereas high adiponectin levels showed a significant 8% increase in risk of ischemic stroke (n=13,683; 7 studies), with a more sizable association observed among men compared to women. HDL was observed to have a marginal effect on the association between adiponectin and ischemic stroke, while other evaluated parameters were not found to be effect modifiers. A non-significant association of adiponectin with mortality was yielded (n=663; OR: 2.58; 95% CI: 0.69-9.62; 3 studies). Although no publication bias was evident, there was significant between-study heterogeneity in most analyses. CONCLUSION: It appears that the direction of the relationship between adiponectin and carotid atherosclerotic plaque presence is dependent on the duration, severity, and nature of the underlying disease, while increased adiponectin levels were associated with an increase in risk for ischemic stroke. Lastly, the results from the mortality meta-analysis remain inconclusive. Future properly designed studies are necessary to further elucidate the role of adiponectin on atherosclerotic plaque development, and its related outcomes.

Circulating adiponectin and carotid intima-media thickness: A systematic review and meta-analysis.

BACKGROUND: Adiponectin (APN) is an adipokine with insulin-sensitizing, anti-inflammatory, and vasculoprotective properties. Hypoadiponectinemia has been linked with disease states, such as obesity, type 2 diabetes, and cardiovascular disease. Carotid intima-media thickness (cIMT) is a strong and independent predictor of both coronary and cerebrovascular events, and has been used as a surrogate marker of subclinical atherosclerosis. The aim of this report is to systematically review the evidence on the relationship between APN and cIMT in a wide range of individuals. MATERIALS AND METHODS: Medline, Embase, Biosis, Scopus, Web of Science, and Pubmed were searched for published studies and conference abstracts. The "sign test" and "vote count" methods were used to estimate the direction and significance of the relationship between APN and cIMT. The quality of the eligible studies was evaluated using an adapted version of the New Castle Ottawa quality assessment scale. RESULTS: Fifty-five articles fulfilled the inclusion criteria, comprised of only cross-sectional studies, including healthy subjects, general population, and individuals with metabolic, inflammatory, or other chronic diseases. Most associations between APN and cIMT followed a negative direction in the healthier and general populations, and also in cohorts with metabolic disorders and other chronic diseases, but not in those with inflammatory diseases (sign test). These associations were generally found to be weak or non-significant among all cohort groups studied (vote count). CONCLUSION: Our results are suggestive but not conclusive for an inverse association between APN levels and cIMT in diseased and non-diseased populations.

Circulating Chemerin Is Associated With Carotid Plaque Instability, Whereas Resistin Is Related to Cerebrovascular Symptomatology.

OBJECTIVE: The rupture of unstable carotid atherosclerotic plaques is one of the main causes of cerebrovascular ischemic events. There is need for circulating markers that can predict plaque instability and risk of stroke. Proinflammatory chemerin, leptin, and resistin, along with anti-inflammatory adiponectin, are adipokines with direct influence on vascular function. We investigated the association of circulating adipokines with carotid plaque instability and cerebrovascular symptomatology. APPROACH AND RESULTS: Neurologically symptomatic and asymptomatic patients (n=165) scheduled for carotid endarterectomy were recruited. Fasting blood samples were collected preoperatively; adiponectin and leptin levels were determined by radioimmunoassay; and chemerin and resistin levels were measured by enzyme-linked immunosorbent assays. The instability of plaque specimens was assessed using gold-standard histological classifications. Chemerin was significantly associated with plaque instability. The fully adjusted model, accounting for age, sex, body mass index, high-sensitivity C-reactive protein, type 2 diabetes mellitus, and circulating adiponectin, leptin, and resistin, yielded an odds ratio of 0.991 (95% confidence interval 0.985-0.998) for plaque instability per unit increase in chemerin. High leptin levels were significantly associated with presence of specific features of plaque instability. In subjects with type 2 diabetes mellitus, resistin levels were significantly elevated in symptomatic when compared with asymptomatic subjects (P=0.001) and increased the risk of cerebrovascular symptomatology (adjusted odds ratio 1.264, 95% confidence interval 1.004-1.594). CONCLUSIONS: Low chemerin and high resistin levels were associated with carotid disease severity, suggesting that these adipokines may act as potential markers for plaque instability and stroke risk. Future studies are needed to assess causation between circulating adipokines and plaque instability.

Mechanisms of radiation-induced sensorineural hearing loss and radioprotection.

Patients that receive radiotherapy are at risk of late sensorineural hearing loss when the inner ear is included within the radiation field. Preclinical and human temporal bone studies have shown that there is differential damage to cochlear structures depending on the amount of dose delivered to the inner ear. In vitro studies have suggested that reactive oxygen species (ROS) are the main initial actors in radiation-induced damage. The interaction of ROS with different cellular components can result in different apoptotic pathways. Therefore, approaches to radioprotection are mainly aimed to reduce ROS production through antioxidants. This review summarizes recent research in the field that can improve the understanding and boost preventive efforts of this adverse effect.

The effect of caffeine on hearing in a guinea pig model of acoustic trauma.

OBJECTIVE: Caffeine is a widely consumed substance affecting the metabolism of adenosine and cellular metabolism of calcium. Noise also affects these metabolic pathways while inducing hearing loss. The aim of this study was to determine the effect of daily intake of caffeine on hearing loss after an episode of acoustic trauma in guinea pigs. MATERIALS AND METHODS: In this pilot study, forty guinea pigs were randomly divided into four groups: group I (control, n=10) received intraperitoneal saline, group II (n=10) received intraperitoneal caffeine (120 mg/kg/day) for 14 days, group III (n=10) was exposed to noise (tone of 6 kHz at 120 dB for one hour) and group IV (n=10) was exposed to noise as group III and received caffeine as group II. Auditory brainstem responses were measured at four different frequencies (8, 16, 20, and 25 kHz) prior to and at intervals of 1h, 3 days, 10 days, and 14 days after the initial treatment. On day 14, morphological analysis was performed to assess the effects of caffeine on acoustic trauma. RESULTS: Aggravated hearing loss was observed in group IV after 10 days of follow-up. After 14 days, one of the four frequencies (8 kHz) tested showed statistically significant greater impairment in hearing (8.2 ± 3.6 dB, p=0.026). Auditory hair cells showed no difference while spiral ganglion cell counts were diminished in group IV (p<0.05). CONCLUSION: These findings indicate that caffeine may have a detrimental effect on hearing recovery after a single event of acoustic trauma.