Circulating nonesterified fatty acid level as a predictive risk factor for sudden death in the population

Free fatty acids and mortality among adults in the United States: a report from US National Health and Nutrition Examination Survey (NHANES)

BACKGROUND

The relationship between free fatty acids (FFAs) and the risk of mortality remains unclear. There is a scarcity of prospective studies examining the associations between specific FFAs, rather than total concentrations, of their effect on long-term health outcomes.

OBJECTIVE

To evaluate the correlation between different FFAs and all-cause and cardiovascular mortality in a large, diverse, nationally representative sample of adults in the US, and examine how different FFAs may mediate this association.

METHODS

This cohort study included unsaturated fatty acids (USFA) and saturated fatty acids (SFA) groups in the US National Health and Nutrition Examination Survey (NHANES) from 2011 to 2014 and provided blood samples for FFAs levels. Multiple model calibration was performed using Cox regression analysis for known risk factors to explore the associations between FFAs and all-cause and cardiovascular mortality.

RESULTS

In the group of USFA, 3719 people were included, median follow-up, 6.7 years (5.8-7.8 years). In the SFA group, we included 3900 people with a median follow-up, 6.9 years (5.9-8 years). In the USFA group, myristoleic acid (14:1 n-5) (hazard ratio (HR) 1.02 [1.006-1.034]; P = 0.004), palmitoleic acid (16:1 n-7) (HR 1.001 [1.001-1.002]; P < 0.001), cis-vaccenic acid (18:1 n-7) (HR 1.006 [1.003-1.009]; P < 0.001), nervonic acid (24:1 n-9) (HR 1.007 [1.002-1.012]; P = 0.003), eicosatrienoic acid (20:3 n-9) (HR 1.027 [1.009-1.046]; P = 0.003), docosatetraenoic acid (22:4 n-6) (HR 1.024 [1.012-1.036]; P < 0.001), and docosapentaenoic acid (22:5 n-6) (HR 1.019 [1.006-1.032]; P = 0.005) were positively associated with the all-cause mortality, while docosahexaenoic acid (22:6 n-3) had a statistically lower risk of all-cause mortality (HR 0.998 [0.996-0.999]; P = 0.007). Among the SFA group, palmitic acid (16:0) demonstrated a higher risk of all-cause mortality (HR 1.00 [1.00-1.00]; P = 0.022), while tricosanoic acid (23:0) (HR 0.975 [0.959-0.991]; P = 0.002) and lignoceric acid (24:0) (HR 0.992 [0.984-0.999]; P = 0.036) were linked to a lower risk of all-cause mortality. Besides 23:0 and 24:0, the other FFAs mentioned above were linearly associated with the risks of all-cause mortality.

CONCLUSIONS

In this nationally representative cohort of US adults, some different FFAs exhibited significant associations with risk of all-cause mortality. Achieving optimal concentrations of specific FFAs may lower this risk of all-cause mortality, but this benefit was not observed in regards to cardiovascular mortality.

Eicosapentaenoic Acid Rescues Cav1.2-L-Type Ca2+ Channel Decline Caused by Saturated Fatty Acids via Both Free Fatty Acid Receptor 4-Dependent and -Independent Pathways in Cardiomyocytes

Dietary intake of omega-3 polyunsaturated fatty acids (eicosapentaenoic acid, EPA) exerts antiarrhythmic effects, although the mechanisms are poorly understood. Here, we investigated the possible beneficial actions of EPA on saturated fatty acid-induced changes in the L-type Ca2+ channel in cardiomyocytes. Cardiomyocytes were cultured with an oleic acid/palmitic acid mixture (OAPA) in the presence or absence of EPA. Beating rate reduction in cardiomyocytes caused by OAPA were reversed by EPA. EPA also retrieved a reduction in Cav1.2 L-type Ca2+ current, mRNA, and protein caused by OAPA. Immunocytochemical analysis revealed a distinct downregulation of the Cav1.2 channel caused by OAPA with a concomitant decrease in the phosphorylated component of a transcription factor adenosine-3',5'-cyclic monophosphate (cAMP) response element binding protein (CREB) in the nucleus, which were rescued by EPA. A free fatty acid receptor 4 (FFAR4) agonist TUG-891 reversed expression of Cav1.2 and CREB mRNA caused by OAPA, whereas an FFAR4 antagonist AH-7614 abolished the effects of EPA. Excessive reactive oxygen species (ROS) accumulation caused by OAPA decreased Cav1.2 and CREB mRNA expressions, which was reversed by an ROS scavenger. Our data suggest that EPA rescues cellular Cav1.2-Ca2+ channel decline caused by OAPA lipotoxicity and oxidative stresses via both free fatty acid receptor 4-dependent and -independent pathways.

The abnormalities of free fatty acid metabolism in patients with hypertrophic cardiomyopathy, a single-center retrospective observational study

BACKGROUND

Previous studies have shown the importance of energy deficiency and malfunctioning mitochondria in the pathophysiology of hypertrophic cardiomyopathy (HCM). There has been a little research into the relationship between plasma free fatty acids (FFA), one of the heart's main energy sources, and HCM. We evaluated its clinical importance in HCM to see if there was a link between plasma FFA metabolism and HCM.

METHODS

In a single-center retrospective observational study, we investigated 420 HCM patients diagnosed at Beijing Anzhen Hospital between January 1, 2018, and December 31, 2022. Meanwhile, 1372 individuals without HCM (non-HCM) were recruited. 391 non-HCM patients were chosen as controls via a propensity score matching (PSM) study with a 1:1 ratio.

RESULTS

FFA in HCM patients showed statistically significant correlations with creatinine (r = 0.115, p = 0.023), estimated GFR (r=-0.130, p = 0.010), BNP (r = 0.152, p = 0.007), LVEF (r=-0.227, p < 0.001), LVFS (r=-0.160, p = 0.002), and LAD (r = 0.112, p = 0.028). Higher FFA levels were found in HCM patients who had atrial fibrillation and NYHY functional classes III or IV (p = 0.015 and p = 0.022, respectively). In HCM patients, multiple linear regression analysis revealed that BNP and LVEF had independent relationships with increasing FFA (Standardized = 0.139, p = 0.013 and =-0.196, p < 0.001, respectively).

CONCLUSIONS

Among HCM patients, the plasma FFA concentration was lower, and those with AF and NYHY functional class III or IV had higher FFA levels, and LVEF and BNP were independently associated with increasing FFA. The findings of the study should help inspire future efforts to better understand how energy deficiency contributes to hypertrophic cardiomyopathy (HCM) development.

Identification of sudden cardiac death from human blood using ATR-FTIR spectroscopy and machine learning

OBJECTIVE

The aim of this study is to identify a rapid, sensitive, and non-destructive auxiliary approach for postmortem diagnosis of SCD, addressing the challenges faced in forensic practice.

METHODS

ATR-FTIR spectroscopy was employed to collect spectral features of blood samples from different cases, combined with pathological changes. Mixed datasets were analyzed using ANN, KNN, RF, and SVM algorithms. Evaluation metrics such as accuracy, precision, recall, F1-score and confusion matrix were used to select the optimal algorithm and construct the postmortem diagnosis model for SCD.

RESULTS

A total of 77 cases were collected, including 43 cases in the SCD group and 34 cases in the non-SCD group. A total of 693 spectrogram were obtained. Compared to other algorithms, the SVM algorithm demonstrated the highest accuracy, reaching 95.83% based on spectral biomarkers. Furthermore, by combing spectral biomarkers with age, gender, and cardiac histopathological changes, the accuracy of the SVM model could get 100%.

CONCLUSION

Integrating artificial intelligence technology, pathology, and physical chemistry analysis of blood components can serve as an effective auxiliary method for postmortem diagnosis of SCD.

Protective effect of vitamin B6 against doxorubicin-induced cardiotoxicity by modulating NHE1 expression

Doxorubicin (DOX) has been used to treat various types of cancer, but its application is limited due to its heart toxicity as well as other drawbacks. Chronic inhibition of Na+ /H+ exchanger (NHE1) reduces heart failure and reduces the production of reactive oxygen species (ROS); vitamin B6 (VitB6 ) has been demonstrated to have a crucial role in antioxidant mechanism. So, this study was designed to explore the effect of VitB6 supplement on the DOX-induced cardiotoxicity and to imply whether NHE1 is involved. Ultrasonic cardiogram analysis revealed that VitB6 supplement could alleviate DOX-induced cardiotoxicity; hematoxylin and eosin (HE) and Masson's staining further confirmed this effect. Furthermore, VitB6 supplement exhibited significant antioxidative stress and antiapoptosis effect, which was evidenced by decreased serum malondialdehyde (MDA) content and increased serum superoxide dismutase (SOD) content, and decreased Bcl-2-associated X protein/B-cell lymphoma-2 ratio, respectively. Collectively, VitB6 supplement may exert antioxidative and antiapoptosis effects to improve cardiac function by decreasing NHE1 expression and improve DOX-induced cardiotoxicity.

Propofol in ICU Settings: Understanding and Managing Anti-Arrhythmic, Pro-Arrhythmic Effects, and Propofol Infusion Syndrome

Propofol has revolutionized anesthesia and intensive care medicine owing to its favorable pharmacokinetic characteristics, fast onset, and short duration of action. This drug has been shown to be remarkably effective in numerous clinical scenarios. In addition, propofol has maintained an overwhelmingly favorable safety profile; however, it has been associated with both antiarrhythmic and proarrhythmic effects. This review concisely summarizes the dual arrhythmic cardiovascular effects of propofol and a rare but serious complication, propofol infusion syndrome (PRIS). We also discuss the need for careful patient evaluation, compliance with recommended infusion rates, and vigilant monitoring.

Propofol-Related Infusion Syndrome: A Clinical Review

Propofol-related infusion syndrome (PRIS) is a lethal condition characterized by multiple organ system failures. It can occur due to prolonged administration of propofol (an anesthetic) in mechanically intubated patients. The main presenting features of this condition include cardiovascular dysfunction with particular emphasis on impairment of cardiovascular contractility, metabolic acidosis, lactic acidosis, rhabdomyolysis, hyperkalaemia, lipidaemia, hepatomegaly, acute renal failure, and eventually mortality in most cases. The significant risk factors that predispose one to PRIS are: critical illnesses, increased serum catecholamines, steroid therapy, obesity, young age (significantly below three years), depleted carbohydrate stores in the body, increased serum lipids, and most importantly, heavy or extended dosage of propofol. The primary pathophysiology behind PRIS is the disruption of the mitochondrial respiratory chain that causes inhibition of adenosine triphosphate (ATP) synthesis and cellular hypoxia. Further, excess lipolysis of adipose tissue occurs, especially in critically ill patients where the energy source is lipid breakdown instead of carbohydrates. This process generates excess free fatty acids (FFAs) that cannot undergo adequate beta-oxidation. These FFAs contribute to the clinical pathology of PRIS. It requires prompt management as it is a fatal condition. The clinicians must observe the patient's electrocardiogram (ECG), serum creatine kinase, lipase, amylase, lactate, liver enzymes, and myoglobin levels in urine, under propofol sedation. Doctors should immediately stop propofol infusion upon noticing any abnormality in these parameters. The other essentials of management of various manifestations of PRIS will be discussed in this article, along with a detailed explanation of the condition, its risk factors, diagnosis, pathophysiology, and presenting features. This article aims to make clinicians more aware of the occurrence of this syndrome so that better ways to manage and treat this condition can be formulated in the future.

Strategies for Therapeutic Amelioration of Aberrant Plasma Zn2+ Handling in Thrombotic Disease: Targeting Fatty Acid/Serum Albumin-Mediated Effects

The initiation, maintenance and regulation of blood coagulation is inexorably linked to the actions of Zn²⁺ in blood plasma. Zn²⁺ interacts with a variety of haemostatic proteins in the bloodstream including fibrinogen, histidine-rich glycoprotein (HRG) and high molecular weight kininogen (HMWK) to regulate haemostasis. The availability of Zn²⁺ to bind such proteins is controlled by human serum albumin (HSA), which binds 70–85% of plasma Zn²⁺ under basal conditions. HSA also binds and transports non-esterified fatty acids (NEFAs). Upon NEFA binding, there is a change in the structure of HSA which leads to a reduction in its affinity for Zn²⁺. This enables other plasma proteins to better compete for binding of Zn²⁺. In diseases where elevated plasma NEFA concentrations are a feature, such as obesity and diabetes, there is a concurrent increase in hypercoagulability. Evidence indicates that NEFA-induced perturbation of Zn²⁺-binding by HSA may contribute to the thrombotic complications frequently observed in these pathophysiological conditions. This review highlights potential interventions, both pharmaceutical and non-pharmaceutical that may be employed to combat this dysregulation. Lifestyle and dietary changes have been shown to reduce plasma NEFA concentrations. Furthermore, drugs that influence NEFA levels such as statins and fibrates may be useful in this context. In severely obese patients, more invasive therapies such as bariatric surgery may be useful. Finally, other potential treatments such as chelation therapies, use of cholesteryl transfer protein (CETP) inhibitors, lipase inhibitors, fatty acid inhibitors and other treatments are highlighted, which with additional research and appropriate clinical trials, could prove useful in the treatment and management of thrombotic disease through amelioration of plasma Zn²⁺ dysregulation in high-risk individuals.

Diet and Sudden Death: How to Reduce the Risk

In addition to the association of dietary patterns, specific foods and nutrients with several diseases, including cardiovascular disease and mortality, there is also strong emerging evidence of an association of dietary patterns with the risk of sudden cardiac death (SCD). In this comprehensive review, data are presented and analyzed about foods and diets that mitigate the risk of ventricular arrhythmias (VAs) and SCD, but also about arrhythmogenic nutritional elements and patterns that seem to enhance or facilitate potentially malignant VAs and SCD. The antiarrhythmic or protective group comprises fish, nuts and other foods enriched in omega-3 polyunsaturated fatty acids, the Mediterranean and other healthy diets, vitamins E, A and D and certain minerals (magnesium, potassium, selenium). The arrhythmogenic-food group includes saturated fat, trans fats, ketogenic and liquid protein diets, the Southern and other unhealthy diets, energy drinks and excessive caffeine intake, as well as heavy alcohol drinking. Relevant antiarrhythmic mechanisms include modification of cell membrane structure by n-3 polyunsaturated fatty acids, their direct effect on calcium channels and cardiomyocytes and their important role in eicosanoid metabolism, enhancing myocyte electric stability, reducing vulnerability to VAs, lowering heart rate, and improving heart rate variability, each of which is a risk factor for SCD. Contrarily, saturated fat causes calcium handling abnormalities and calcium overload in cardiomyocytes, while a high-fat diet causes mitochondrial dysfunction that dysregulates a variety of ion channels promoting VAs and SCD. Free fatty acids have been considered proarrhythmic and implicated in facilitating SCD; thus, diets increasing free fatty acids, e.g., ketogenic diets, should be discouraged and replaced with diets enriched with polyunsaturated fatty acids, which can also reduce free fatty acids. All available relevant data on this important topic are herein reviewed, large studies and meta-analyses and pertinent advisories are tabulated, while protective (antiarrhythmic) and arrhythmogenic specific diet constituents are pictorially illustrated.

The mitochondrial calcium uniporter promotes arrhythmias caused by high-fat diet

Obesity and diabetes increase the risk of arrhythmia and sudden cardiac death. However, the molecular mechanisms of arrhythmia caused by metabolic abnormalities are not well understood. We hypothesized that mitochondrial dysfunction caused by high fat diet (HFD) promotes ventricular arrhythmia. Based on our previous work showing that saturated fat causes calcium handling abnormalities in cardiomyocytes, we hypothesized that mitochondrial calcium uptake contributes to HFD-induced mitochondrial dysfunction and arrhythmic events. For experiments, we used mice with conditional cardiac-specific deletion of the mitochondrial calcium uniporter (Mcu), which is required for mitochondrial calcium uptake, and littermate controls. Mice were used for in vivo heart rhythm monitoring, perfused heart experiments, and isolated cardiomyocyte experiments. MCU KO mice are protected from HFD-induced long QT, inducible ventricular tachycardia, and abnormal ventricular repolarization. Abnormal repolarization may be due, at least in part, to a reduction in protein levels of voltage gated potassium channels. Furthermore, isolated cardiomyocytes from MCU KO mice exposed to saturated fat are protected from increased reactive oxygen species (ROS), mitochondrial dysfunction, and abnormal calcium handling. Activation of calmodulin-dependent protein kinase (CaMKII) corresponds with the increase in arrhythmias in vivo. Additional experiments showed that CaMKII inhibition protects cardiomyocytes from the mitochondrial dysfunction caused by saturated fat. Hearts from transgenic CaMKII inhibitor mice were protected from inducible ventricular tachycardia after HFD. These studies identify mitochondrial dysfunction caused by calcium overload as a key mechanism of arrhythmia during HFD. This work indicates that MCU and CaMKII could be therapeutic targets for arrhythmia caused by metabolic abnormalities.

Association of Serum Nonesterified Fatty Acids with Cardiovascular Event in Patients with Chronic Kidney Disease

Background

Chronic kidney disease (CKD) has been suggested to be associated with a high risk of cardiovascular diseases (CVD). The study aimed to evaluate the prognostic significance of nonesterified fatty acid (NEFA), also well known as free fatty acid, on predicting cardiovascular events in patients with CKD.

Methods

A total of 957 hospitalized patients with CKD in a stable clinical condition were enrolled at baseline. Then, the serum NEFA levels were measured. These included patients were prospectively followed up for a median of 10.2 years (range=0.4–11.5 years). We assessed whether serum NEFA levels at baseline can predict cardiovascular event during the follow-up.

Results

A total of 278 (29.1%) patients experienced cardiovascular events during follow-up. The Kaplan–Meier curve demonstrated that patients with higher serum NEFA levels (≥19.8 mg/dl) had a higher rate of cardiovascular events than patients with lower NEFA levels (<19.8 mg/dl). Multivariate Cox regression analysis suggested that elevated serum NEFA levels (HR=1.62; 95% CI 1.40–2.16, P<0.001) were independently associated with increased risk of cardiovascular events after correction for clinical confounding factors.

Conclusion

Elevated serum NEFA levels were associated with higher risk of cardiovascular events and may be a new parameter predicting cardiovascular events in patients with CKD, which may strengthen its potential effect in clinical practice.

Berberine improves dietary-induced cardiac remodeling by upregulating Kruppel-like factor 4-dependent mitochondrial function

Multiple studies have showed that berberine protects against heart diseases, including obesity-associated cardiomyopathy. However, it is not fully disclosed the potential molecular mechanisms of berberine on controlling cardiac remodeling. Kruppel-like factor (KLF) 4, identified as a critical transcriptional factor, participates in multiple cardiac injuries. The present study was to explore whether KLF4 determined the cardioprotective benefits of berberine in dietary-induced obese mice. High fat diet-induced obese mice were treated with berberine with or without lentivirus encoding Klf4 siRNA, and cardiac parameters were analyzed by multiple biological approaches. In dietary-induced obese mouse model, administration of berberine obviously increased cardiac level of KLF4, which closely correlated with improvement of cardiac functional parameters. Co-treatment of lentivirus encoding Klf4 siRNA abolished cardioprotective benefits of berberine, including induction of cardiac hypertrophy, fibrosis, functional disorders, inflammatory response and oxidative stress. Mechanistically, we found berberine improved cardiac mitochondrial biogenesis and activities, whereas silencing Klf4 decreased berberine-upregulated mitochondrial quality, ATP production and oxygen consumption. Our present study demonstrated that berberine protected against dietary-induced cardiac structural disorders and mitochondrial dysfunction dependent on cardiac KLF4 signaling. Cardiac KLF4 was one of potential therapeutic targets for obesity-induced cardiac injuries.

Nonesterified Fatty Acids and Kidney Function Decline in Older Adults: Findings From the Cardiovascular Health Study

RATIONALE & OBJECTIVE

Circulating nonesterified fatty acids (NEFAs) make up a small portion of circulating lipids but are a metabolically important energy source. Excessive circulating NEFAs may contribute to lipotoxicity in many tissues, including the kidneys. We investigated the relationship between total circulating NEFA concentration and kidney outcomes in older, community-dwelling adults.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

4,698 participants≥65 years of age in the Cardiovascular Health Study who underwent total fasting serum NEFA concentration measurements in 1992-1993.

EXPOSURE

Fasting serum NEFA concentration at one time point.

OUTCOME

Three primary outcomes: estimated glomerular filtration rate (eGFR) decline of≥30%, the composite of eGFR decline≥30% or kidney failure with replacement therapy, and change in eGFR. These outcomes were assessed over 4- and 13-year periods.

ANALYTICAL APPROACH

Logistic regression for the dichotomous outcomes and mixed effects models for the continuous outcome, with sequential adjustment for baseline covariates. Inverse probability of attrition weighting was implemented to account for informative attrition during the follow-up periods.

RESULTS

Serum NEFA concentrations were not independently associated with kidney outcomes. In unadjusted and partially adjusted analyses, the highest quartile of serum NEFA concentration (compared with lowest) was associated with a higher risk of≥30% eGFR decline at 4 years and faster rate of decline of eGFR. No associations were evident after adjustment for comorbidities, lipid levels, insulin sensitivity, medications, and vital signs: the odds ratio for the eGFR decline outcome was 1.33 (95% CI, 0.83-2.13), and the difference in eGFR slope in the highest versus lowest quartile of serum NEFA concentration was-0.15 (95% CI, -0.36 to 0.06) mL/min/1.73m² per year.

LIMITATIONS

Single NEFA measurements, no measurements of post-glucose load NEFA concentrations or individual NEFA species, no measurement of baseline urine albumin.

CONCLUSIONS

A single fasting serum NEFA concentration was not independently associated with long-term adverse kidney outcomes in a cohort of older community-living adults.

Free fatty acids, cardiovascular disease, and mortality in the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Fasting free fatty acid (FFA) levels may be associated with cardiovascular disease (CVD) and mortality, but research among generally healthy adults, females, and racially/ethnically diverse populations is lacking.

OBJECTIVE

The primary aim of this project was to investigate prospective associations between fasting FFAs and coronary heart disease (CHD) and CVD incidence and CVD-specific and all-cause mortality in a generally healthy age, sex, and racially/ethnically heterogeneous population.

METHODS

This study was conducted in the Multi-Ethnic Study of Atherosclerosis cohort using baseline (2000-2002) fasting FFAs and outcome data through 2015 (N = 6678). Cox proportional hazards regression was used to calculate hazard ratios for associations between FFAs and CHD, CVD, CVD-specific mortality, and all-cause mortality. Interactions by age, sex, race/ethnicity, and metabolic syndrome were evaluated by stratification and cross-product terms. A secondary analysis was conducted to evaluate associations between FFAs, and inflammatory and endothelial activation biomarkers were evaluated using linear regression (analytic N range: 964-6662).

RESULTS

FFA levels were not associated with CHD or CVD incidence. Higher FFAs were associated with CVD-specific and all-cause mortality, but associations were attenuated in fully adjusted models with a borderline significant association remaining only for all-cause mortality (fully adjusted, per standard deviation increase hazard ratio = 1.07, 95% confidence interval: 1.00-1.14). Associations did not differ by age, sex, race/ethnicity, or metabolic syndrome.

CONCLUSIONS

Fasting FFAs were not associated with CHD, CVD, or CVD-specific mortality and were modestly associated with all-cause mortality, regardless of age, sex, race/ethnicity, or metabolic syndrome status.

Anti-arrhythmic properties of non-antiarrhythmic medications

Traditional anti-arrhythmic drugs are classified by the Vaughan-Williams classification scheme based on their mechanisms of action, which includes effects on receptors and/or ion channels. Some known anti-arrhythmic drugs do not perfectly fit into this classification scheme. Other medications/molecules with established non-anti-arrhythmic indications have shown anti-arrhythmic properties worth exploring. In this narrative review, we discuss the molecular mechanisms and evidence base for the anti-arrhythmic properties of traditional non-antiarrhythmic drugs such as inhibitors of the renin angiotensin system (RAS), statins and polyunsaturated fatty acids (PUFAs). In summary, RAS antagonists, statins and PUFAs are 'upstream target modulators' that appear to have anti-arrhythmic roles. RAS blockers prevent the downstream arrhythmogenic effects of angiotensin II - the main effector peptide of RAS - and the angiotensin type 1 receptor. Statins have pleiotropic effects including anti-inflammatory, immunomodulatory, modulation of autonomic nervous system, anti-proliferative and anti-oxidant actions which appear to underlie their anti-arrhythmic properties. PUFAs have the ability to alter ion channel function and prevent excessive accumulation of calcium ions in cardiac myocytes, which might explain their benefits in certain arrhythmic conditions. Clearly, whilst a number of anti-arrhythmic drugs exist, there is still a need for randomised trials to establish whether additional agents, including those already in clinical use, have significant anti-arrhythmic effects.

Classic and Novel Biomarkers as Potential Predictors of Ventricular Arrhythmias and Sudden Cardiac Death

Sudden cardiac death (SCD), most often induced by ventricular arrhythmias, is one of the main reasons for cardiovascular-related mortality. While coronary artery disease remains the leading cause of SCD, other pathologies like cardiomyopathies and, especially in the younger population, genetic disorders, are linked to arrhythmia-related mortality. Despite many efforts to enhance the efficiency of risk-stratification strategies, effective tools for risk assessment are still missing. Biomarkers have a major impact on clinical practice in various cardiac pathologies. While classic biomarkers like brain natriuretic peptide (BNP) and troponins are integrated into daily clinical practice, inflammatory biomarkers may also be helpful for risk assessment. Indeed, several trials investigated their application for the prediction of arrhythmic events indicating promising results. Furthermore, in recent years, active research efforts have brought forward an increasingly large number of “novel and alternative” candidate markers of various pathophysiological origins. Investigations of these promising biological compounds have revealed encouraging results when evaluating the prediction of arrhythmic events. To elucidate this issue, we review current literature dealing with this topic. We highlight the potential of “classic” but also “novel” biomarkers as promising tools for arrhythmia prediction, which in the future might be integrated into clinical practice.

Vitamin B6 inhibits macrophage activation to prevent lipopolysaccharide-induced acute pneumonia in mice

Macrophage activation participates in the pathogenesis of pulmonary inflammation. As a coenzyme, vitamin B6 (VitB6) is mainly involved in the metabolism of amino acids, nucleic acids, glycogen and lipids. We have previously reported that activation of AMP‐activated protein kinase (AMPK) produces anti‐inflammatory effects both in vitro and in vivo. Whether VitB6 via AMPK activation prevents pulmonary inflammation remains unknown. The model of acute pneumonia was induced by injecting mice with lipopolysaccharide (LPS). The inflammation was determined by measuring the levels of interleukin‐1 beta (IL‐1β), IL‐6 and tumour necrosis factor alpha (TNF‐α) using real time PCR, ELISA and immunohistochemistry. Exposure of cultured primary macrophages to VitB6 increased AMP‐activated protein kinase (AMPK) Thr172 phosphorylation in a time/dose‐dependent manner, which was inhibited by compound C. VitB6 downregulated the inflammatory gene expressions including IL‐1β, IL‐6 and TNF‐α in macrophages challenged with LPS. These effects of VitB6 were mirrored by AMPK activator 5‐aminoimidazole‐4‐carboxamide ribonucleoside (AICAR). However, VitB6 was unable to inhibit LPS‐induced macrophage activation if AMPK was in deficient through siRNA‐mediated approaches. Further, the anti‐inflammatory effects produced by VitB6 or AICAR in LPS‐treated macrophages were abolished in DOK3 gene knockout (DOK3^−/−) macrophages, but were enhanced in macrophages if DOK3 was overexpressed. In vivo studies indicated that administration of VitB6 remarkably inhibited LPS‐induced both systemic inflammation and acute pneumonia in wild‐type mice, but not in DOK3^−/− mice. VitB6 prevents LPS‐induced acute pulmonary inflammation in mice via the inhibition of macrophage activation.

The role of implantable cardioverter-defibrillators and sudden cardiac death prevention: indications, device selection, and outcome

Multiple randomized multicentre clinical trials have established the role of the implantable cardioverter-defibrillator (ICD) as the mainstay in the treatment of ventricular tachyarrhythmias and sudden cardiac death (SCD) prevention. These trials have focused mainly on heart failure patients with advanced left ventricular dysfunction and were mostly conducted two decades ago, whereas a more recent trial has provided conflicting results. Therefore, much remains to be determined on how best to balance the identification of patients at high risk of SCD together with who would benefit most from ICD implantation in a contemporary setting. Implantable cardioverter-defibrillators have also evolved from the simple, defibrillation-only devices implanted surgically to more advanced technologies of multi-chamber devices, with physiologic bradycardic pacing, including cardiac resynchronization therapy, atrial and ventricular therapeutic pacing algorithms, and subcutaneous ICDs. These multiple options necessitate individualized approach to device selection and programming. This review will focus on the current knowledge on selection of patients for ICD treatment, device selection and programming, and future directions of implantable device therapy for SCD prevention.

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Dietary Saturated Fat Promotes Arrhythmia by Activating NOX2 (NADPH Oxidase 2)

BACKGROUND

Obesity and diets high in saturated fat increase the risk of arrhythmias and sudden cardiac death. However, the molecular mechanisms are not well understood. We hypothesized that an increase in dietary saturated fat could lead to abnormalities of calcium homeostasis and heart rhythm by a NOX2 (NADPH oxidase 2)-dependent mechanism.

METHODS

We investigated this hypothesis by feeding mice high-fat diets. In vivo heart rhythm telemetry, optical mapping, and isolated cardiac myocyte imaging were used to quantify arrhythmias, repolarization, calcium transients, and intracellular calcium sparks.

RESULTS

We found that saturated fat activates NOX (NADPH oxidase), whereas polyunsaturated fat does not. The high saturated fat diet increased repolarization heterogeneity and ventricular tachycardia inducibility in perfused hearts. Pharmacological inhibition or genetic deletion of NOX2 prevented arrhythmogenic abnormalities in vivo during high statured fat diet and resulted in less inducible ventricular tachycardia. High saturated fat diet activates CaMK (Ca2+/calmodulin-dependent protein kinase) in the heart, which contributes to abnormal calcium handling, promoting arrhythmia.

CONCLUSIONS

We conclude that NOX2 deletion or pharmacological inhibition prevents the arrhythmogenic effects of a high saturated fat diet, in part mediated by activation of CaMK. This work reveals a molecular mechanism linking cardiac metabolism to arrhythmia and suggests that NOX2 inhibitors could be a novel therapy for heart rhythm abnormalities caused by cardiac lipid overload.

Sudden Cardiac Death (SCD) - risk stratification and prediction with molecular biomarkers

Sudden cardiac death (SCD) is a sudden, unexpected death that is caused by the loss of heart function. While SCD affects many patients suffering from coronary artery diseases (CAD) and heart failure (HF), a considerable number of SCD events occur in asymptomatic individuals. Certain risk factors for SCD have been identified and incorporated in different clinical scores, however, risk stratification using such algorithms is only useful for health management rather than for early detection and prediction of future SCD events in high-risk individuals. In this review, we discuss different molecular biomarkers that are used for early detection of SCD. This includes genetic biomarkers, where the majority of them are genomic variants for genes that encode for ion channels. Meanwhile, protein biomarkers often denote proteins that play roles in pathophysiological processes that lead to CAD and HF, notably (i) atherosclerosis that involves oxidative stress and inflammation, as well as (ii) cardiac tissue damage that involves neurohormonal and hemodynamic regulation and myocardial stress. Finally, we outline existing challenges and future directions including the use of OMICS strategy for biomarker discovery and the multimarker panels.

Predictors of cardiac arrhythmic events in non coronary artery disease patients

Arrhythmic sudden cardiac death (SCD) represents a major worldwide public health problem accounting for 15–20% of deaths. Risk stratification to identify patients at risk of SCD is crucial in order to implement preventive measures in the general population. Several biomarkers have been tested exploring different pathophysiological mechanisms of cardiac conditions. Conflicting results have been described limiting so far their use in clinical practice. The use of new biomarkers such as microRNAs and sex hormones and the emerging role of genetic on risk prediction of SCD is a current research topic showing promising results.

This review outlines the role of plasma biomarkers to predict ventricular arrhythmias and SCD in non coronary artery disease with a special focus on their relationship with the genetic biomarkers.

Free Fatty Acids' Level and Nutrition in Critically Ill Patients and Association with Outcomes: A Prospective Sub-Study of PermiT Trial

OBJECTIVES

The objectives of this study were to evaluate the clinical and nutritional correlates of high free fatty acids (FFAs) level in critically ill patients and the association with outcomes, and to study the effect of short-term caloric restriction (permissive underfeeding) on FFAs level during critical illness.

PATIENTS/METHOD

In this pre-planned sub-study of the PermiT (Permissive Underfeeding vs. Target Enteral Feeding in Adult Critically Ill Patients) trial, we included critically ill patients who were expected to stay for ≥14 days in the intensive care unit. We measured FFAs level on day 1, 3, 5, 7, and 14 of enrollment. Of 70 enrolled patients, 23 (32.8%) patients had high FFAs level (baseline FFAs level >0.45 mmol/L in females and >0.6 mmol/L in males).

RESULTS

Patients with high FFAs level were significantly older and more likely to be females and diabetics and they had lower ratio of partial pressure of oxygen to the fraction of inspired oxygen, higher creatinine, and higher total cholesterol levels than those with normal FFAs level. During the study period, patients with high FFAs level had higher blood glucose and required more insulin. On multivariable logistic regression analysis, the predictors of high baseline FFAs level were diabetes (adjusted odds ratio (aOR): 5.36; 95% confidence interval (CI): 1.56, 18.43, p = 0.008) and baseline cholesterol level (aOR, 4.29; 95% CI: 11.64, 11.19, p = 0.003). Serial levels of FFAs did not differ with time between permissive underfeeding and standard feeding groups. FFAs level was not associated with 90-day mortality (aOR: 0.49; 95% CI: 0.09, 2.60, p = 0.40).

CONCLUSION

We conclude that high FFAs level in critically ill patients is associated with features of metabolic syndrome and is not affected by short-term permissive underfeeding.

Clinical Overview of Obesity and Diabetes Mellitus as Risk Factors for Atrial Fibrillation and Sudden Cardiac Death

The epidemics of obesity and diabetes mellitus are associated with an increased incidence of both atrial fibrillation (AF), the most common sustained arrhythmia in adults, and sudden cardiac death (SCD). Obesity and DM are known to have adverse effects on cardiac structure and function. The pathologic mechanisms are thought to involve cardiac tissue remodeling, metabolic dysregulation, inflammation, and oxidative stress. Clinical data suggest that left atrial size, epicardial fat pad thickness, and other modifiable risk factors such as hypertension, glycemic control, and obstructive sleep apnea may mediate the association with AF. Data from human atrial tissue biopsies demonstrate alterations in atrial lipid content and evidence of mitochondrial dysfunction. With respect to ventricular arrhythmias, abnormalities such as long QT syndrome, frequent premature ventricular contractions, and left ventricular hypertrophy with diastolic dysfunction are commonly observed in obese and diabetic humans. The increased risk of SCD in this population may also be related to excessive cardiac lipid deposition and insulin resistance. While nutritional interventions have had limited success, perhaps due to poor long-term compliance, weight loss and improved cardiorespiratory fitness may reduce the frequency and severity of AF.

Omega-3 Polyunsaturated Fatty Acids: Benefits and Endpoints in Sport

The influence of nutrition has the potential to substantially affect physical function and body metabolism. Particular attention has been focused on omega-3 polyunsaturated fatty acids (n-3 PUFAs), which can be found both in terrestrial features and in the marine world. They are responsible for numerous cellular functions, such as signaling, cell membrane fluidity, and structural maintenance. They also regulate the nervous system, blood pressure, hematic clotting, glucose tolerance, and inflammatory processes, which may be useful in all inflammatory conditions. Animal models and cell-based models show that n-3 PUFAs can influence skeletal muscle metabolism. Furthermore, recent human studies demonstrate that they can influence not only the exercise and the metabolic response of skeletal muscle, but also the functional response for a period of exercise training. In addition, their potential anti-inflammatory and antioxidant activity may provide health benefits and performance improvement especially in those who practice physical activity, due to their increased reactive oxygen production. This review highlights the importance of n-3 PUFAs in our diet, which focuses on their potential healthy effects in sport.

Lipid Profiles in Out-of-Hospital Sudden Unexpected Death

Objective

To determine the association between serum lipid measurements and the occurrence of out-of-hospital sudden unexpected death (OHSUD).

Patients and Methods

We compared 139 OHSUD cases (43 female patients [30.9%]) and 968 controls (539 female patients [55.7%]) from Wake County, North Carolina, from March 1, 2013, through February 28, 2015. Individuals were included if they were aged 18 to 64 years and had lipid measurements in the 5 years before their death (cases) or the most recent health care encounter (controls). Covariates were abstracted from medical records for all subjects, and those with triglyceride (TG) levels greater than 400 mg/dL (to convert to mmol/L, multiply by 0.0259) were excluded for low-density lipoprotein (LDL)–related analyses.

Results

By linear regression using age- and sex-adjusted models, cases of OHSUD had lower adjusted mean total cholesterol (170.3±52.2 mg/dL vs 188.9±39.7 mg/dL; P<.001), LDL cholesterol (90.9±39.6 mg/dL vs 109.6±35.2 mg/dL; P<.001), and non–high-density lipoprotein (HDL) (121.6±49.8 mg/dL vs 134.3±39.6 mg/dL; P<.001) levels and a higher adjusted TG/HDL-C ratio (4.7±7 vs 3±2.7; P<.001) than did controls. By logistic regression using age- and sex-adjusted models, the odds of OHSUD were elevated per unit increase in TG/HDL-C ratio (1.08; 95% CI, 1.03-1.12).

Conclusion

Out-of-hospital sudden unexpected death cases had more favorable levels of total cholesterol, LDL cholesterol, and non-HDL, possibly indicating a lack of association between traditional lipid cardiovascular risk factors and sudden unexpected death. A comparatively elevated TG/HDL-C ratio in cases may corroborate an evolving hypothesis of how vasoactive and prothrombotic remnant-like lipoprotein particles contribute to sudden unexpected death.

Polyunsaturated fatty acids, inflammation, and metabolic syndrome in South Asian Americans in Maryland

Metabolic syndrome (MetS) is characterized by the accumulation of cardiovascular risk factors among men and women worldwide. The use of very long-chain polyunsaturated fatty acids (VLC PUFA) could potentially benefit individuals with MetS. The goal was to better understand the relationship between MetS and VLC PUFA in South Asian (SA) Americans who experience an elevated risk for heart disease. We analyzed a cross section of South Asian (SA) using the automated self-administered 24-hr recall (ASA24) and clinic data in a low-income SA in Maryland. We found no correlation between MetS indicators (high-density lipoprotein (HDL) cholesterol, triglycerides, fasting blood glucose, diastolic blood pressure, and waist circumference (WC)) and dietary n-3 PUFA (eicosapentaenoic, docosapentaenoic acids). However, dietary n-6 VLC PUFA (arachidonic acid [AA]) was associated with cholesterol and fasting blood glucose levels. SA with MetS did not have a significantly low level of dietary VLC PUFA intake, and there were no SA group differences in the intake of VLC PUFA but there were significant gender differences. Dietary practices in SA may contribute to increased proinflammatory markers and play a role in elevated MetS components.

Adiponectin, Free Fatty Acids, and Cardiovascular Outcomes in Patients With Type 2 Diabetes and Acute Coronary Syndrome

OBJECTIVE

In observational cohorts, adiponectin is inversely associated and free fatty acids (FFAs) are directly associated with incident coronary heart disease (CHD). Adiponectin tends to be reduced and FFAs elevated in type 2 diabetes. We investigated relationships of adiponectin and FFA and major adverse cardiovascular events (MACEs) and death in patients with acute coronary syndrome (ACS) and type 2 diabetes using data from the AleCardio (Effect of Aleglitazar on Cardiovascular Outcomes After Acute Coronary Syndrome in Patients With Type 2 Diabetes Mellitus) trial, which compared the PPAR-α/γ agonist aleglitazar with placebo.

RESEARCH DESIGN AND METHODS

Using Cox regression adjusted for demographic, laboratory, and treatment variables, we determined associations of baseline adiponectin and FFAs, or the change in adiponectin and FFAs from baseline, with MACEs (cardiovascular death, myocardial infarction, or stroke) and death.

RESULTS

A twofold higher baseline adiponectin (n = 6,998) was directly associated with risk of MACEs (hazard ratio [HR] 1.17 [95% CI 1.08-1.27]) and death (HR 1.53 [95% CI 1.35-1.73]). A doubling of adiponectin from baseline to month 3 (n = 6,325) was also associated with risk of death (HR 1.20 [95% CI 1.03-1.41]). Baseline FFAs (n = 7,038), but not change in FFAs from baseline (n = 6,365), were directly associated with greater risk of MACEs and death. There were no interactions with study treatment.

CONCLUSIONS

In contrast to prior observational data for incident CHD, adiponectin is prospectively associated with MACEs and death in patients with type 2 diabetes and ACS, and an increase in adiponectin from baseline is directly related to death. These findings raise the possibility that adiponectin has different effects in patients with type 2 diabetes and ACS than in populations without prevalent cardiovascular disease. Consistent with prior data, FFAs are directly associated with adverse outcomes.

Biomarkers to Predict Cardiovascular Death

This article reviews biomarkers that have been shown to identify subjects at increased risk for cardiovascular death within the general population, in those with established coronary artery disease, and in those with heart failure. Use of biomarkers for risk stratification for sudden cardiac death continues to evolve. It seems that a multimarker strategy for risk stratification using simple measures of circulating proteins and usual clinical risk factors, particularly in patients with known coronary artery disease, can be used to identify patients at near-term risk of death. Whether similar strategies in the general population will prove to be cost-effective needs to be investigated.

Sudden Cardiac Death in Ischemic Heart Disease: Pathophysiology and Risk Stratification

Sudden cardiac death (SCD) accounts for approximately 360,000 deaths annually in the United States. Ischemic heart disease is the major cause of death in the general adult population. SCD can be due to arrhythmic or nonarrhythmic cardiac causes. Arrhythmic SCD may be caused by ventricular tachyarrhythmia or pulseless electrical activity/asystole. This article reviews the most recent pathophysiology and risk stratification strategies for SCD, emphasizing electrophysiologic surrogates of conduction disorder, dispersion of repolarization, and autonomic imbalance. Factors that modify arrhythmic death are addressed.

Monotherapy of experimental metabolic syndrome: II. Study of cardiovascular effects

Metabolic syndrome belongs to the most important risk factors of cardiovascular diseases. The aim of this study was to investigate changes in cardiovascular system induced by high cholesterol and high fat diet (HCHF) in HTG rats and their influence by a pyridoindole antioxidant - SMe1EC2 (S). The effects of S were compared with those of atorvastatin (A). Male HTG rats were fed HCHF (1% cholesterol + 7.5% lard) for 4 weeks. S and A were administered p.o., 50 mg/kg b.w. Following experimental groups were used: Wistar rats (W), hypertriglyceridemic rats (HTG), HTG rats fed HCHF (CHOL), HTG+S (S-HTG), CHOL+S (S-CHOL), and CHOL+A (A-CHOL). Values of blood pressure (BP) and selected ECG parameters were monitored in conscious animals, functions of the isolated heart and aorta were analyzed ex vivo. At the end of the experiment, systolic (sBP) and diastolic (dBP) blood pressure was increased in HTG and CHOL. S and A decreased BP in all treated groups. Accordingly with BP changes, the aortic endothelial function of CHOL was damaged. Both S and A administration ameliorated the endothelium-dependent relaxation to values of W. PQ and QTc intervals were prolonged in CHOL, while the treatment with S or A improved ECG findings. Prodysrhythmogenic threshold was decreased significantly in CHOL and both treatments returned it to the control values. In conclusion, HCHF increased BP, impaired endothelial relaxation of the aorta and potentiated susceptibility of myocardium to dysrhythmias. The effect of S on the changes induced by HCHF diet was more pronounced than that of A.

Proinflammatory Cytokines Are Soluble Mediators Linked with Ventricular Arrhythmias and Contractile Dysfunction in a Rat Model of Metabolic Syndrome

Metabolic syndrome (MS) increases cardiovascular risk and is associated with cardiac dysfunction and arrhythmias, although the precise mechanisms are still under study. Chronic inflammation in MS has emerged as a possible cause of adverse cardiac events. Male Wistar rats fed with 30% sucrose in drinking water and standard chow for 25–27 weeks were compared to a control group. The MS group showed increased weight, visceral fat, blood pressure, and serum triglycerides. The most important increases in serum cytokines included IL-1β (7-fold), TNF-α (84%), IL-6 (41%), and leptin (2-fold), the latter also showing increased gene expression in heart tissue (35-fold). Heart function ex vivo in MS group showed a decreased mechanical performance response to isoproterenol challenge (ISO). Importantly, MS hearts under ISO showed nearly twofold the incidence of ventricular fibrillation. Healthy rat cardiomyocytes exposed to MS group serum displayed impaired contractile function and Ca²⁺ handling during ISO treatment, showing slightly decreased cell shortening and Ca²⁺ transient amplitude (23%), slower cytosolic calcium removal (17%), and more frequent spontaneous Ca²⁺ release events (7.5-fold). As spontaneous Ca²⁺ releases provide a substrate for ventricular arrhythmias, our study highlights the possible role of serum proinflammatory mediators in the development of arrhythmic events during MS.

Vitamin B6 prevents isocarbophos-induced vascular dementia in rats through N-methyl-D-aspartate receptor signaling

BACKGROUND

We have previously reported that the long-term exposure of organophosphorus induces vascular dementia (VD) in rats. As a coenzyme, vitamin B6 is mainly involved in the regulation of metabolisms. Whether vitamin B6 improves VD remains unknown.

METHODS

The model of VD was induced by feeding rats with isocarbophos (0.5 mg/kg per two day, 12 weeks). The blood flow of the posterior cerebral artery (PCA) in rat was assessed by transcranial Doppler (TCD). The learning and memory were evaluated by the Morris Water Maze (MWM) test.

RESULTS

Administration of vitamin B6 increased the blood flow in the right and left posterior cerebral arteries and improved the functions of learning and memory in isocarbophos-treated rats. Vitamin B6 increased the protein levels of N-methyl-D-aspartate receptor (NMDAR) 2B, postsynaptic densities (PSDs) protein 95, and calmodulin-dependent protein kinase II (CaMK-II) in the hippocampus, which were decreased by isocarbophos in rats. Morphological analysis by light microscope and electronic microscope indicated disruptions of the hippocampus caused by isocarbophos were normalized by vitamin B6. Importantly, the antagonist of NMDAR signaling by eliprodil abolished these beneficial effects produced by vitamin B6 on PCA blood flow, learning, memory, and hippocampus structure in rats, as well as the protein expression of NMDAR 2B, PSDs protein 95, and CaMK-II in the hippocampus.

CONCLUSION

Vitamin B6 activates NMDAR signaling to prevent isocarbophos-induced VD in rats.

[Sudden cardiac death: A better understanting for a better prevention]

Sudden cardiac death is defined as a natural and unexpected death, in a previous apparently healthy individual. It represents a major public health issue, with up to 50% of the cardiovascular mortality. Using data from the Paris Sudden Death Expertise Centre registry, this article summarises the main cardiovascular abnormalities associated with sudden cardiac death, the different preventives approaches, and provides a systematic diagnostic approach.

Key Questions for Translation of FFA Receptors: From Pharmacology to Medicines

The identification of fatty acids as ligands for the G-protein coupled free fatty acid (FFA) receptor family over 10 years ago led to intensive chemistry efforts to find small-molecule ligands for this class of receptors. Identification of potent, selective modulators of the FFA receptors and their utility in medicine has proven challenging, in part due to their complex pharmacology. Nevertheless, ligands have been identified that are sufficient for exploring the therapeutic potential of this class of receptors in rodents and, in the case of FFA1, FFA2, FFA4, and GPR84, also in humans. Expression profiling, the phenotyping of FFA receptor knockout mice, and the results of studies exploring the effects of these ligands in rodents have uncovered a number of indications where engagement of one or a combination of FFA receptors might provide some clinical benefit in areas including diabetes, inflammatory bowel syndrome, Alzheimer's, pain, and cancer. In this chapter, we will review the clinical potential of modulating FFA receptors based on preclinical and in some cases clinical studies with synthetic ligands. In particular, key aspects and challenges associated with small-molecule ligand identification and FFA receptor pharmacology will be addressed with a view of the hurdles that need to be overcome to fully understand the potential of the receptors as therapeutic targets.

Drug induced mitochondrial dysfunction: Mechanisms and adverse clinical consequences

Several commonly used medications impair mitochondrial function resulting in adverse effects or toxicities. Drug induced mitochondrial dysfunction may be a consequence of increased production of reactive oxygen species, altered mitochondrial permeability transition, impaired mitochondrial respiration, mitochondrial DNA damage or inhibition of beta-oxidation of fatty acids. The clinical manifestation depends on the specific drug and its effect on mitochondria. Given the ubiquitous presence of mitochondria and its central role in cellular metabolism, drug-mitochondrial interactions may manifest clinically as hepatotoxicity, enteropathy, myelosuppression, lipodystrophy syndrome or neuropsychiatric adverse effects, to name a few. The current review focuses on specific drug groups which adversely affect mitochondria, the mechanisms involved and the clinical consequences based on the data available from experimental and clinical studies. Knowledge of these adverse drug-mitochondrial interactions may help the clinicians foresee potential issues in individual patients, prevent adverse drug reactions or alter drug regimens to enhance patient safety.

Quantification of total content of non-esterified fatty acids bound to human serum albumin

Non-esterified fatty acids bound to the human serum albumin (HSA) contribute to several HSAs properties of special concern in pathologies, for instance to the reactivity of the free HSA-Cys34 thiol group (important antioxidative thiol pool in plasma), and to the affinity for binding of molecules and ions (for example cobalt as a prominent biomarker in heart ischemia). Therefore, the method for determination of FAs bound to HSA was developed. FAs were released from HSA (previously isolated from serum by ammonium sulfate precipitation) using acidic copper(II) sulfate in phosphoric acid, extracted by n-heptane-chloroform (4:1, v/v) mixture, spotted on TL silica-gel and then developed with n-heptane-chloroform-acetic acid (5:3:0.3, v/v/v). Common office flatbed scanner and software solution for densitometric image analysis, developed in R, were used. The linearity of calibration curve in concentration range from 0.1 to 5.0mmol/L stearic acid was achieved. The method was proved to be precise (with RSD of 1.4-4.7%) and accurate. Accuracy was examined by standard addition method (recoveries 97.2-102.5%) and by comparison to results of GC. The method is sample saving, technically less demanding, and cheap, and therefore suitable for determination of FAs/HSA ratio when elevated concentrations of free FAs are reliable diagnostic/risk parameter of pathological states.

Integrative analysis of metabolome and gut microbiota in diet-induced hyperlipidemic rats treated with berberine compounds

Background

Hyperlipidemia is a major component of metabolic syndrome, and often predicts cardiovascular diseases. We developed a new therapeutic agent berberine compounds (BC), consisting of berberine, oryzanol and vitamin B₆, and determined their anti-hyperlipidemia activity and underlying mechanisms.

Methods

Male Wistar rats were fed a high fat diet (HFD) to induce hyperlipidemia, and then given BC orally for 4 weeks. Body weight and food intake were recorded weekly, and lipid profiles in serum were determined biochemically. Metabolites in serum, urine, liver and feces were analyzed by GC–MS, and the structure of microbiota was determined by 16S rDNA sequencing.

Results

Lipid lowering was observed in the hyperlipidemic rats upon BC treatment without apparent adverse side effects. Metabolomics analysis indicated that the BC treatment resulted in increased pyruvic acid, serotonin, and ketogenic and glycogenic amino acid levels in the serum, increased pyridoxine and 4-pyridoxic acid in the urine, decreased hypotaurine and methionine in the liver, and increased putrescine and decreased deoxycholate and lithocholate in feces. The BC treatment also resulted in an enrichment of beneficial bacteria (e.g. Bacteroides, Blautia) and a decrease in Escherichia.

Conclusions

The lipid lowering effect of BC treatment in hyperlipidemic rats is associated with a global change in the metabolism of lipids, carbohydrates and amino acids, as well as the structure of microbiota.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0987-5) contains supplementary material, which is available to authorized users.

Serum-Based Oxylipins Are Associated with Outcomes in Primary Prevention Implantable Cardioverter Defibrillator Patients

Introduction

Individuals with systolic heart failure are at risk of ventricular arrhythmias and all-cause mortality. Little is known regarding the mechanisms underlying these events. We sought to better understand if oxylipins, a diverse class of lipid metabolites derived from the oxidation of polyunsaturated fatty acids, were associated with these outcomes in recipients of primary prevention implantable cardioverter defibrillators (ICDs).

Methods

Among 479 individuals from the PROSE-ICD study, baseline serum were analyzed and quantitatively profiled for 35 known biologically relevant oxylipin metabolites. Associations with ICD shocks for ventricular arrhythmias and all-cause mortality were evaluated using Cox proportional hazards models.

Results

Six oxylipins, 17,18-DiHETE (HR = 0.83, 95% CI 0.70 to 0.99 per SD change in oxylipin level), 19,20-DiHDPA (HR = 0.79, 95% CI 0.63 to 0.98), 5,6-DiHETrE (HR = 0.73, 95% CI 0.58 to 0.91), 8,9-DiHETrE (HR = 0.76, 95% CI 0.62 to 0.95), 9,10-DiHOME (HR = 0.81, 95% CI 0.65 to 1.00), and PGF_1α (HR = 1.33, 95% CI 1.04 to 1.71) were associated with the risk of appropriate ICD shock after multivariate adjustment for clinical factors. Additionally, 4 oxylipin-to-precursor ratios, 15S-HEPE / FA (20:5-ω3), 17,18-DiHETE / FA (20:5-ω3), 19,20-DiHDPA / FA (20:5-ω3), and 5S-HEPE / FA (20:5-ω3) were positively associated with the risk of all-cause mortality.

Conclusion

In a prospective cohort of patients with primary prevention ICDs, we identified several novel oxylipin markers that were associated with appropriate shock and mortality using metabolic profiling techniques. These findings may provide new insight into the potential biologic pathways leading to adverse events in this patient population.

Effect of Selenium Deficiency on Phosphorylation of the AMPK Pathway in Rats

Selenium is an important trace element for human health. Previous studies have raised concern that dietary selenium intake may change energy metabolism. AMP-activated protein kinase (AMPK) is a sensor of energy status that controls cellular energy homeostasis. We aimed to determine the effect of selenium on the phosphorylation of AMPK pathway between Se-deficient and normal Sprague-Dawley rats. Twenty-four weaning rats were fed either a Se-deficient diet (0.02 mg Se/kg) or a standard diet (0.18 mg Se/kg). After 109 days, total serum levels of non-esterified fatty acid and total amino acids were significantly higher and the serum insulin concentration was significantly lower in Se-deficient rats than in healthy controls. Selenium concentration and the activity of glutathione peroxidase (GPx) in myocardial tissue were significantly lower in Se-deficient rats. Importantly, mRNA levels of acetyl-CoA carboxylase beta (ACACB), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), and protein levels of p-AMPKα were increased in the Se-deficient group compared to normal controls (p < 0.05). In conclusion, our results suggest that selenium deficiency induces changes in metabolic and molecular parameters involved in energy metabolism in the AMPK pathway.

Inhibition of NAPDH Oxidase 2 (NOX2) Prevents Oxidative Stress and Mitochondrial Abnormalities Caused by Saturated Fat in Cardiomyocytes

Obesity and high saturated fat intake increase the risk of heart failure and arrhythmias. The molecular mechanisms are poorly understood. We hypothesized that physiologic levels of saturated fat could increase mitochondrial reactive oxygen species (ROS) in cardiomyocytes, leading to abnormalities of calcium homeostasis and mitochondrial function. We investigated the effect of saturated fat on mitochondrial function and calcium homeostasis in isolated ventricular myocytes. The saturated fatty acid palmitate causes a decrease in mitochondrial respiration in cardiomyocytes. Palmitate, but not the monounsaturated fatty acid oleate, causes an increase in both total cellular ROS and mitochondrial ROS. Palmitate depolarizes the mitochondrial inner membrane and causes mitochondrial calcium overload by increasing sarcoplasmic reticulum calcium leak. Inhibitors of PKC or NOX2 prevent mitochondrial dysfunction and the increase in ROS, demonstrating that PKC-NOX2 activation is also required for amplification of palmitate induced-ROS. Cardiomyocytes from mice with genetic deletion of NOX2 do not have palmitate-induced ROS or mitochondrial dysfunction. We conclude that palmitate induces mitochondrial ROS that is amplified by NOX2, causing greater mitochondrial ROS generation and partial depolarization of the mitochondrial inner membrane. The abnormal sarcoplasmic reticulum calcium leak caused by palmitate could promote arrhythmia and heart failure. NOX2 inhibition is a potential therapy for heart disease caused by diabetes or obesity.

Vitamin B6 Prevents Endothelial Dysfunction, Insulin Resistance, and Hepatic Lipid Accumulation in Apoe (-/-) Mice Fed with High-Fat Diet

Backgrounds. VitB6 deficiency has been associated with a number of adverse health effects. However, the effects of VitB6 in metabolic syndrome are poorly understood. Methods. VitB6 (50 mg/kg/day) was given to Apoe (-/-) mice with hkdigh-fat diet (HFD) for 8 weeks. Endothelial dysfunction, insulin resistance, and hepatic lipid contents were determined. Results. VitB6 administration remarkably increased acetylcholine-induced endothelium-dependent relaxation and decreased random blood glucose level in Apoe (-/-) mice fed with HFD. In addition, VitB6 improved the tolerance of glucose and insulin, normalized the histopathology of liver, and reduced hepatic lipid accumulation but did not affect the liver functions. Clinical and biochemical analysis indicated that the levels of VitB6 were decreased in patients with fatty liver. Conclusions. Vitamin B6 prevents endothelial dysfunction, insulin resistance, and hepatic lipid accumulation in Apoe (-/-) mice fed with HFD. Supplementation of VitB6 should be considered to prevent metabolic syndrome.

Sudden Cardiac Death Risk Stratification - An Update

Sudden cardiac death (SCD) remains a major public health problem worldwide, yet current methods to identify those at greatest risk are inadequate. High-risk individuals may benefit from potentially life-saving treatment, such as insertion of an implantable-cardioverter defibrillator (ICD). However, such treatments are expensive and have their own associated risks. Furthermore, most cases of SCD occur in the general adult population who may be relatively asymptomatic but yet have an underlying predisposition to SCD. Hence, there is great interest and clinical need in improving methods for risk stratification of SCD to identify those at greatest risk and implement the most appropriate treatment. This review provides an update on current risk-stratification methods for SCD in high-risk groups, in particular patients with reduced left ventricular function following acute myocardial infarction and those with non-ischaemic dilated cardiomyopathy, and highlights some novel methods that may have a role to play in future risk-stratification schemes. Approaches and challenges for SCD risk stratification among the general public are also discussed.

Propofol infusion syndrome: a structured review of experimental studies and 153 published case reports

INTRODUCTION

Propofol infusion syndrome (PRIS) is a rare, but potentially lethal adverse effect of a commonly used drug. We aimed to review and correlate experimental and clinical data about this syndrome.

METHODS

We searched for all case reports published between 1990 and 2014 and for all experimental studies on PRIS pathophysiology. We analysed the relationship between signs of PRIS and the rate and duration of propofol infusion causing PRIS. By multivariate logistic regression we looked at the risk factors for mortality.

RESULTS

Knowledge about PRIS keeps evolving. Compared to earlier case reports in the literature, recently published cases describe older patients developing PRIS at lower doses of propofol, in whom arrhythmia, hypertriglyceridaemia and fever are less frequently seen, with survival more likely. We found that propofol infusion rate and duration, the presence of traumatic brain injury and fever are factors independently associated with mortality in reported cases of PRIS (area under receiver operator curve = 0.85). Similar patterns of exposure to propofol (in terms of time and concentration) are reported in clinical cases and experimental models of PRIS. Cardiac failure and metabolic acidosis occur early in a dose-dependent manner, while arrhythmia, other electrocardiographic changes and rhabdomyolysis appear more frequently after prolonged propofol infusions, irrespective of dose.

CONCLUSION

PRIS can develop with propofol infusion <4 mg/kg per hour and its diagnosis may be challenging as some of its typical features (hypertriglyceridaemia, fever, hepatomegaly, heart failure) are often (>95 %) missing and others (arrhythmia, electrocardiographic changes) occur late.

Sudden cardiac death risk stratification

Arrhythmic sudden cardiac death (SCD) may be caused by ventricular tachycardia/fibrillation or pulseless electric activity/asystole. Effective risk stratification to identify patients at risk of arrhythmic SCD is essential for targeting our healthcare and research resources to tackle this important public health issue. Although our understanding of SCD because of pulseless electric activity/asystole is growing, the overwhelming majority of research in risk stratification has focused on SCD-ventricular tachycardia/ventricular fibrillation. This review focuses on existing and novel risk stratification tools for SCD-ventricular tachycardia/ventricular fibrillation. For patients with left ventricular dysfunction or myocardial infarction, advances in imaging, measures of cardiac autonomic function, and measures of repolarization have shown considerable promise in refining risk. Yet the majority of SCD-ventricular tachycardia/ventricular fibrillation occurs in patients without known cardiac disease. Biomarkers and novel imaging techniques may provide further risk stratification in the general population beyond traditional risk stratification for coronary artery disease alone. Despite these advances, significant challenges in risk stratification remain that must be overcome before a meaningful impact on SCD can be realized.

Propofol infusion syndrome in adults: a clinical update

Propofol infusion syndrome is a rare but extremely dangerous complication of propofol administration. Certain risk factors for the development of propofol infusion syndrome are described, such as appropriate propofol doses and durations of administration, carbohydrate depletion, severe illness, and concomitant administration of catecholamines and glucocorticosteroids. The pathophysiology of this condition includes impairment of mitochondrial beta-oxidation of fatty acids, disruption of the electron transport chain, and blockage of beta-adrenoreceptors and cardiac calcium channels. The disease commonly presents as an otherwise unexplained high anion gap metabolic acidosis, rhabdomyolysis, hyperkalemia, acute kidney injury, elevated liver enzymes, and cardiac dysfunction. Management of overt propofol infusion syndrome requires immediate discontinuation of propofol infusion and supportive management, including hemodialysis, hemodynamic support, and extracorporeal membrane oxygenation in refractory cases. However, we must emphasize that given the high mortality of propofol infusion syndrome, the best management is prevention. Clinicians should consider alternative sedative regimes to prolonged propofol infusions and remain within recommended maximal dose limits.

Glycated albumin with loss of fatty acid binding capacity contributes to enhanced arachidonate oxygenation and platelet hyperactivity: relevance in patients with type 2 diabetes

High plasma concentrations of nonesterified fatty acids (NEFAs), transported bound to serum albumin, are associated with type 2 diabetes (T2D). The effects of albumin on platelet function were investigated in vitro. Modifications of albumin, such as those due to glycoxidation, were found in patients with T2D, and the consequences of these modifications on biological mechanisms related to NEFA handling were investigated. Mass spectrometry profiles of albumin from patients with T2D differed from those from healthy control subjects. Diabetic albumin showed impaired NEFA binding capacity, and both structural and functional alterations could be reproduced in vitro by incubating native albumin with glucose and methylglyoxal. Platelets incubated with albumin isolated from patients with T2D aggregated approximately twice as much as platelets incubated with albumin isolated from healthy control subjects. Accordingly, platelets incubated with modified albumin produced significantly higher amounts of arachidonate metabolites than did platelets incubated with control albumin. We concluded that higher amounts of free arachidonate are made available for the generation of active metabolites in platelets when the NEFA binding capacity of albumin is blunted by glycoxidation. This newly described mechanism, in addition to hypoalbuminemia, may contribute to platelet hyperactivity and increased thrombosis, known to occur in patients with T2D.

Biomarkers in electrophysiology: role in arrhythmias and resynchronization therapy

Circulating biomarkers related to inflammation, neurohormones, myocardial stress, and necrosis have been associated with commonly encountered arrhythmic disorders such as atrial fibrillation (AF) and more malignant processes including ventricular arrhythmias (VA) and sudden cardiac death (SCD). Both direct and indirect biomarkers implicated in the heart failure cascade have potential prognostic value in patients undergoing cardiac resynchronization therapy (CRT). This review will focus on the role of biomarkers in AF, history of SCD, and CRT with an emphasis to improve clinical risk assessment for arrhythmias and patient selection for device therapy. Notably, information obtained from biomarkers may supplement traditional diagnostic and imaging techniques, thus providing an additional benefit in the management of patients.

Nonesterified fatty acids and cardiovascular mortality in elderly men with CKD

BACKGROUND AND OBJECTIVES

Although nonesterified fatty acids (NEFAs) are essential as energy substrate for the myocardium, an excess of circulating NEFAs can be harmful. This study aimed to assess plausible relationships between serum NEFA and mortality due to cardiovascular disease (CVD) in individuals with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a prospective cohort study from the third examination cycle of the Uppsala Longitudinal Study of Adult Men, a population-based survey of 1221 elderly men aged 70-71 years residing in Uppsala, Sweden. Data collection took place during 1991-1995. All participants had measures of kidney function; this study investigated 623 (51.7%) of these patients with manifest CKD (defined as either eGFR<60 ml/min per 1.73 m(2) or urine albumin excretion rate ≥20 µg/min). Follow-up for mortality was done from examination date until death or December 31, 2007. After a median follow-up of 14 years (interquartile range, 8-16.8), associations of NEFAs with mortality (related to all causes, CVD, ischemic heart disease [IHD], or acute myocardial infarction) were ascertained.

RESULTS

The median serum NEFA was 14.1 mg/dl (interquartile range, 11.3-17.8). No association was found with measures of kidney function. Diabetes and serum triglycerides were the only multivariate correlates of NEFA. During follow-up, 453 participants died, of which 209 deaths were due to CVD, including 88 IHD deaths, with 41 attributed to acute myocardial infarction (AMI). In fully adjusted covariates, serum NEFA was an independent risk factor for all-cause mortality (hazard ratio [HR] per log2 increase, 1.22; 95% confidence interval [95% CI], 1.00 to 1.48) and CVD-related death (HR, 1.51; 95% CI, 1.15 to 1.99), including both IHD (HR, 1.51; 95% CI, 1.00 to 2.32) and AMI mortality (HR, 2.08; 95% CI, 1.09 to 3.98).

CONCLUSIONS

Elevated serum NEFA associated with CVD mortality, and particularly with mortality due to AMI, in a homogeneous population of older men with moderate CKD.

Elevated Free Fatty Acid is Associated with Cardioembolic Stroke Subtype

Background and Objectives:

Free fatty acids (FFAs), an important energy substrate, have an association with cardiovascular diseases, such as atherosclerosis, myocardial dysfunction and abnormal cardiac rhythm. However, limited reports are available on the association between FFAs and ischemic stroke. We hypothesized that plasma FFA concentration could be associated with an ischemic stroke, emphasizing the relationship between FFA and subtypes of ischemic stroke.

Methods:

A cross-sectional study examined the association between FFA concentration and subtypes of stroke and cerebral atherosclerosis from a hospital-based acute stroke registry.

Results:

Data of 715 stroke patients were analyzed. The concentration of FFA was highest in the cardioembolic stroke subtype compared with the other stroke subtypes. Logistic regression analysis revealed that an increase in FFA concentration was significantly associated with the cardioembolic subtype after the adjustment of covariates. FFA concentration was also higher in patients with atrial fibrillation (AF) than those without AF. According to the presence of atherosclerotic stenosis, no significantly difference of FFA concentration was found for intracranial and extracranial cerebral arterial atherosclerosis.

Conclusion:

Here we report a significant association between fasting FFA concentration and the cardioembolic stroke subtype. AF is suggested as the mediating factor between FFA and the cardioembolic stroke subtype.

Fatty acids and the risk of death during acute myocardial ischaemia

Plasma free fatty acids (non-esterified fatty acids) increase in the first hour of the onset of acute myocardial ischaemia. This results from catecholamine stimulation of adipose tissue lipolysis. It can lead to a metabolic crisis in the injured myocardium with the development of ventricular arrhythmias and increased early mortality. Preconditioning, β-adrenergic blockade and glucose–insulin–potassium are possible therapeutic approaches, but anti-lipolytic agents, such as some nicotinic acid derivatives, can reduce plasma free fatty acid concentrations within minutes and have untried potential. A clinical trial of their effectiveness is needed from the first moment when a patient with an acute coronary syndrome is seen by paramedics.