Measurement of endothelial cell free radical generation: evidence for a central mechanism of free radical injury in postischemic tissues

Empagliflozin improves mitochondrial dysfunction in diabetic cardiomyopathy by modulating ketone body metabolism and oxidative stress

Ketone bodies are considered as an alternative energy source for diabetic cardiomyopathy (DCM) and can improve the energy supply of the heart muscle, suggesting that it may be an important area of research and development as a therapeutic target for DCM. Cumulative cardiovascular trials have shown that sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce cardiovascular events in diabetic populations. Whether SGLT2 inhibitors improve DCM by enhancing ketone body metabolism remains and whether they help prevent oxidative damage remains to be clarified. Here, we present the combined results of nine GSE datasets for diabetic cardiomyopathy (GSE215979, GSE161931, GSE145294, GSE161052, GSE173384, GSE123975, GSE161827, GSE210612, and GSE5606). We found significant up-regulated gene 3-hydroxymethylglutaryl CoA synthetase 2 (HMGCS2) and down-regulated gene 3-hydroxybutyrate dehydrogenase (BDH1) and 3-oxoacid CoA-transferase1 (OXCT1), respectively. Based on the analysis of the constructed protein interaction network, it was found that HMGCS2 was in the core position of the interaction network. In addition, Gene ontology (GO) enrichment analysis mainly focused on redox process, acyl-CoA metabolic process, catalytic activity, redox enzyme activity and mitochondria. The activity of HMGCS2 in DCM heart was increased, while the expression of ketolysis enzymes BDH1 and OXCT1 was inhibited. In vivo, Empagliflozin (Emp) treated DCM group significantly decreased ventricular weight, myocardial cell cross-sectional area, and myocardial fibrosis. In addition, Emp further promoted the activity of BDH1 and OXCT1, increased the utilization of ketone bodies, further promoted the activity of HMGCS2 in DCM, and increased the synthesis of ketone bodies, prevented mitochondrial breakage and dysfunction, increased myocardial ATP to provide sufficient energy, inhibited oxidative stress and apoptosis of cardiac cells ex vivo, and improved the myocardial dysfunction of DCM. Emp can improve mitochondrial dysfunction in diabetic cardiomyopathy by regulating ketone body metabolism and oxidative stress. These findings provide a theoretical basis for evaluating Emp as a treatment for DCM.

Classic Phytochemical Antioxidant and Lipoxygenase Inhibitor, Nordihydroguaiaretic Acid, Activates Phospholipase D through Oxidant Signaling and Tyrosine Phosphorylation Leading to Cytotoxicity in Lung Vascular Endothelial Cells

Nordihydroguaiaretic acid (NDGA), a dicatechol and phytochemical polyphenolic antioxidant and an established inhibitor of human arachidonic acid (AA) 5-lipoxygenase (LOX) and 15-LOX, is widely used to ascertain the role of LOXs in vascular endothelial cell (EC) function. As the modulatory effect of NDGA on phospholipase D (PLD), an important lipid signaling enzyme in ECs, thus far has not been reported, here we have investigated the modulation of PLD activity and its regulation by NDGA in the bovine pulmonary artery ECs (BPAECs). NDGA induced the activation of PLD (phosphatidic acid formation) in cells in a dose- and time-dependent fashion that was significantly attenuated by iron chelator and antioxidants. NDGA induced the formation of reactive oxygen species (ROS) in cells in a dose- and time-dependent manner as evidenced from fluorescence microscopy and fluorimetry of ROS and electron paramagnetic resonance spectroscopy of oxygen radicals. Also, NDGA caused a dose-dependent loss of intracellular glutathione (GSH) in BPAECs. Protein tyrosine kinase (PTyK)-specific inhibitors significantly attenuated NDGA-induced PLD activation in BPAECs. NDGA also induced a dose- and time-dependent phosphorylation of tyrosine in proteins in cells. NDGA caused in situ translocation and relocalization of both PLD₁ and PLD₂ isoforms, in a time-dependent fashion. Cyclooxygenase (COX) inhibitors were ineffective in attenuating NDGA-induced PLD activation in BPAECs, thus ruling out the activation of COXs by NDGA. NDGA inhibited the AA-LOX activity and leukotriene C₄ (LTC₄) formation in cells. On the other hand, the 5-LOX-specific inhibitors, 5, 8, 11, 14-eicosatetraynoic acid and kaempferol, were ineffective in activating PLD in BPAECs. Antioxidants and PTyK-specific inhibitors effectively attenuated NDGA cytotoxicity in BPAECs. The PLD-specific inhibitor, 5-fluoro-2-indolyl deschlorohalopemide (FIPI), significantly attenuated and protected against the NDGA-induced PLD activation and cytotoxicity in BPAECs. For the first time, these results demonstrated that NDGA, the classic phytochemical polyphenolic antioxidant and LOX inhibitor, activated PLD causing cytotoxicity in ECs through upstream oxidant signaling and protein tyrosine phosphorylation.

Commentary: On the merit of an early contributor of the "Preparation for Oxidative Stress" (POS) theory

This commentary acknowledges the contributions of the Ukrainian biologist, Dr. Volodymyr Lushchak, to the understanding of the physiological adaptive strategy called "Preparation for Oxidative Stress" (POS). In the 1990s, various studies revealed that activities of antioxidant enzymes rose in animals under hypometabolic conditions. These timely observations allowed scientists to propose that this increase could prepare animals for reoxygenation events following the release of oxygen restriction, but in doing so, would trigger oxidative damage, hence the use of the term "preparation". Over next 25 years, the phenomenon was described in detail in more than one hundred studies of animals under conditions of aestivation, hypoxia/anoxia, freezing, severe dehydration, ultraviolet exposure, air exposure of water-breathing animals, salinity stress, and others. The POS phenomenon remained without a mechanistic explanation until 2013, when it was proposed that a small increase in oxyradical formation during hypoxia exposure (in hypoxia-tolerant animals) could activate redox-sensitive transcription factors that, in turn, would initiate transcription and translation of antioxidant enzymes. Dr. Lushchak, who studied goldfish under severe hypoxia in the 1990s, had actually proposed the increased production of oxyradicals under this condition and concluded that it would lead to an upregulation of antioxidant enzymes, the hallmark of the POS strategy. However, his research partner at the time, Dr. Hermes-Lima, thought the idea did not have sufficient evidence to support it and recommended the removal of this explanation. In those days, the main line of thinking was that increased oxyradical formation under hypoxia was "impossible". So, as it turns out, the ideas of Dr. Lushchak were well ahead of his time. It then took >10 years before the biochemical and molecular mechanisms responsible for triggering the POS response were clarified. In the present article, this fascinating history is described to highlight Dr. Lushchak's contributions and insights about the POS theory.

Sex-dependent association analysis between serum uric acid and spontaneous hemorrhagic transformation in patients with ischemic stroke

Objective

The association between serum uric acid (UA) and spontaneous hemorrhagic transformation (HT) has been seldom studied, and the role of UA in spontaneous HT remains unclear. This study aims to investigate the sex-dependent association between UA and spontaneous HT in patients with ischemic stroke.

Method

We retrospectively included patients with ischemic stroke in a tertiary academic hospital between December 2016 and May 2020. Patients were included if they presented within 24 h after the onset of symptoms and did not receive reperfusion therapy. Spontaneous HT was determined by an independent evaluation of neuroimaging by three trained neurologists who were blinded to clinical data. A univariate analysis was performed to identify factors related to spontaneous HT. Four logistic regression models were established to adjust each factor and assess the association between UA and spontaneous HT.

Results

A total of 769 patients were enrolled (64.6% were male patients and 3.9% had HT). After adjusting the confounders with a P < 0.05 (model A) in the univariate analysis, the ratio of UA and its interquartile range (RUI) was independently associated with spontaneous HT in male patients (OR: 1.85; 95% CI: 1.07-3.19; P = 0.028), but not in female patients (OR: 1.39; 95% CI: 0.28-6.82; P = 0.685). In models B-D, the results remain consistent with model A after the adjustment for other potential confounders.

Conclusions

Higher serum UA was independently associated with a higher occurrence of spontaneous HT in male patients who were admitted within 24 h after the stroke onset without receiving reperfusion therapy.

Atrial nitroso-redox balance and refractoriness following on-pump cardiac surgery: a randomized trial of atorvastatin

AIMS

Systemic inflammation and increased activity of atrial NOX2-containing NADPH oxidases have been associated with the new onset of atrial fibrillation (AF) after cardiac surgery. In addition to lowering LDL-cholesterol, statins exert rapid anti-inflammatory and antioxidant effects, the clinical significance of which remains controversial.

METHODS AND RESULTS

We first assessed the impact of cardiac surgery and cardiopulmonary bypass (CPB) on atrial nitroso-redox balance by measuring NO synthase (NOS) and GTP cyclohydrolase-1 (GCH-1) activity, biopterin content, and superoxide production in paired samples of the right atrial appendage obtained before (PRE) and after CPB and reperfusion (POST) in 116 patients. The effect of perioperative treatment with atorvastatin (80 mg once daily) on these parameters, blood biomarkers, and the post-operative atrial effective refractory period (AERP) was then evaluated in a randomized, double-blind, placebo-controlled study in 80 patients undergoing cardiac surgery on CPB. CPB and reperfusion led to a significant increase in atrial superoxide production (74% CI 71-76%, n = 46 paired samples, P < 0.0001) and a reduction in atrial tetrahydrobiopterin (BH4) (34% CI 33-35%, n = 36 paired samples, P < 0.01), and in GCH-1 (56% CI 55-58%, n = 26 paired samples, P < 0.001) and NOS activity (58% CI 52-67%, n = 20 paired samples, P < 0.001). Perioperative atorvastatin treatment prevented the effect of CPB and reperfusion on all parameters but had no significant effect on the postoperative right AERP, troponin release, or NT-proBNP after cardiac surgery.

CONCLUSION

Perioperative statin therapy prevents post-reperfusion atrial nitroso-redox imbalance in patients undergoing on-pump cardiac surgery but has no significant impact on postoperative atrial refractoriness, perioperative myocardial injury, or markers of postoperative LV function.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT01780740.

Hyperuricemia is Associated With 2- and 5-Year Adverse Outcomes in Patients With ST-Segment Elevation Myocardial Infarction Undergoing Percutaneous Coronary Intervention

BACKGROUND

Hyperuricemia has recently been identified as a risk factor of cardiovascular diseases; however, prognostic value of hyperuricemia in patients with ST-segment elevation myocardial infarction (STEMI) remained unclear. Simultaneously, the mechanism of this possible relationship has not been clarified. At present, some views believe that hyperuricemia may be related to the inflammatory response. Our study aimed to investigate the association between hyperuricemia and long-term poor prognosis and inflammation in STEMI patients undergoing percutaneous coronary intervention (PCI).

METHODS

A total of 1,448 consecutive patients with STEMI were studied throughout 2013 at a single center. The primary endpoint was all-cause death at 2- and 5-year follow-up. Inflammatory biomarkers were collected on admission of those patients: high sensitive C-reactive protein (hs-CRP), erythrocyte sedimentation rate (ESR), and white blood cell (WBC) count.

RESULTS

Hyperuricemia was associated with higher 2- and 5-year all-cause death in STEME patients compared to normouricemia (5.5% vs. 1.4%, P <0.001; 8.0% vs 3.9%, P = 0.004; respectively). After multivariable adjustment, hyperuricemia was still an independent predictor of 2-year all-cause death (hazard ratio (HR) =4.332, 95% confidence interval (CI): 1.990-9.430, P <0.001) and 5-year all-cause death (HR =2.063, 95% CI: 1.186-3.590, P =0.010). However, there was no difference in hs-CRP, ESR, and WBC count on admission in STEMI patients with hyperuricemia compared to normouricemia (P >0.05).

CONCLUSIONS

Hyperuricemia was associated with higher risks of 2- and 5-year all-cause deaths in patients with STEMI undergoing PCI. However, this study did not find a correlation between hyperuricemia and inflammatory responses in newly admitted STEMI patients.

Sulfide and transition metals - A partnership for life

Sulfide and transition metals often came together in Biology. The variety of possible structural combinations enabled living organisms to evolve an array of highly versatile metal-sulfide centers to fulfill different physiological roles. The ubiquitous iron‑sulfur centers, with their structural, redox, and functional diversity, are certainly the best-known partners, but other metal-sulfide centers, involving copper, nickel, molybdenum or tungsten, are equally crucial for Life. This review provides a concise overview of the exclusive sulfide properties as a metal ligand, with emphasis on the structural aspects and biosynthesis. Sulfide as catalyst and as a substrate is discussed. Different enzymes are considered, including xanthine oxidase, formate dehydrogenases, nitrogenases and carbon monoxide dehydrogenases. The sulfide effect on the activity and function of iron‑sulfur, heme and zinc proteins is also addressed.

Hyperuricemia-induced endothelial insulin resistance: the nitric oxide connection

Hyperuricemia, defined as elevated serum concentrations of uric acid (UA) above 416 µmol L^-1, is related to the development of cardiometabolic disorders, probably via induction of endothelial dysfunction. Hyperuricemia causes endothelial dysfunction via induction of cell apoptosis, oxidative stress, and inflammation; however, it's interfering with insulin signaling and decreased endothelial nitric oxide (NO) availability, resulting in the development of endothelial insulin resistance, which seems to be a major underlying mechanism for hyperuricemia-induced endothelial dysfunction. Here, we elaborate on how hyperuricemia induces endothelial insulin resistance through the disruption of insulin-stimulated endothelial NO synthesis. High UA concentrations decrease insulin-induced NO synthesis within the endothelial cells by interfering with insulin signaling at either the receptor or post-receptor levels (i.e., proximal and distal steps). At the proximal post-receptor level, UA impairs the function of the insulin receptor substrate (IRS) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) in the insulin signaling pathway. At the distal level, high UA concentrations impair endothelial NO synthase (eNOS)-NO system by decreasing eNOS expression and activity as well as by direct inactivation of NO. Clinically, UA-induced endothelial insulin resistance is translated into impaired endothelial function, impaired NO-dependent vasodilation, and the development of systemic insulin resistance. UA-lowering drugs may improve endothelial function in subjects with hyperuricemia.

Detection and structural analysis of lipid-derived radicals in vitro and in vivo

Lipids can be oxidized by reactive oxygen species, resulting in lipid peroxidation and the formation of reactive metabolites such as lipid-derived electrophiles. These products have been reported to induce inflammation, angiogenesis, and ferroptosis. Lipid peroxidation can produce many different products, each of which performs a different function, and which can be challenging to detect in vivo. The initial products of lipid oxidation are lipid-derived radicals, which can cause extensive chain reactions leading to lipid peroxidation. Hence, the ability to detect lipid radicals may provide information about this important class of molecules and the mechanism by which they cause cellular and tissue damage in a wide range of oxidative conditions. In this review, we report recent scientific advances in the detection of lipid-derived radicals in vitro and in cultured cells. We also introduce the possibility of visualization and structural analysis of lipid-derived radicals generated not only in in cells but also in animal tissue samples from oxidative disease models, using fluorescence-based lipid radicals' detection probes. We anticipate that the various innovative techniques summarized in this paper will be applied and further developed to clarify the role of lipid peroxidation in the pathogenesis of oxidative stress-associated diseases.

Multimodal Imaging of Microvascular Abnormalities in Retinal Vein Occlusion

The technologies of ocular imaging modalities such as optical coherence tomography (OCT) and OCT angiography (OCTA) have progressed remarkably. Of these in vivo imaging modalities, recently advanced OCT technology provides high-resolution images, e.g., histologic imaging, enabling anatomical analysis of each retinal layer, including the photoreceptor layers. Recently developed OCTA also visualizes the vascular networks three-dimensionally, which provides better understanding of the retinal deep capillary layer. In addition, ex vivo analysis using autologous aqueous or vitreous humor shows that inflammatory cytokine levels including vascular endothelial growth factor (VEGF) are elevated and correlated with the severity of macular edema (ME) in eyes with retinal vein occlusion (RVO). Furthermore, a combination of multiple modalities enables deeper understanding of the pathology. Regarding therapy, intravitreal injection of anti-VEGF drugs provides rapid resolution of ME and much better visual improvements than conventional treatments in eyes with RVO. Thus, the technologies of examination and treatment for managing eyes with RVO have progressed rapidly. In this paper, we review the multimodal imaging and therapeutic strategies for eyes with RVO with the hope that it provides better understanding of the pathology and leads to the development of new therapies.

Serum uric acid level negatively correlated with the prevalence of clopidogrel low response in patients undergoing antiplatelet treatment with aspirin and clopidogrel

BACKGROUND AND AIMS

It has been reported that elevated serum uric acid (SUA) is related to inflammation and potentially to platelet hyper-reactivity. However, the relationship between elevated SUA and residual platelet reactivity is uncertain in patients on dual antiplatelet treatment (DAPT) with aspirin and clopidogrel.

METHODS AND RESULTS

A cross-sectional cohort study was conducted on 2569 patients undergoing DAPT with aspirin and clopidogrel. Patients' SUA levels, residual platelet aggregation, routine blood tests and clinical characteristics were recorded. The relationship between SUA level and residual platelet aggregation was assessed by correlation analysis, and the relationship between SUA level and the prevalence of clopidogrel low response (CLR) was assessed by multivariate logistic regression analysis. Adenosine diphosphate (ADP) induced platelet aggregation (PL_ADP) was higher in normal-SUA group than that in hyperuricemia group [30(21, 40) % vs. 27(19, 39) %, p = 0.032]. No significant difference was found for arachidonic acid (AA) induced platelet aggregation (PL_AA) between the two groups [4(2, 5) % vs. 3(2, 5) %, p = 0.557]. The correlation between SUA and PL_ADP was statistically significant(r = -0.115, p < 0.001), while that between SUA and PL_AA was non-significant (r = -0.012, p = 0.643). Using the multivariate logistic regression analysis, higher SUA concentration was associated with a decreased risk of clopidogrel low response (CLR) (OR [95%CI] = 0.997 [0.995-0.999], p = 0.001).

CONCLUSION

This is the largest study to date showing that in patients receiving DAPT with aspirin and clopidogrel, SUA is independently and negatively associated with the prevalence of clopidogrel low response.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov Unique Identifier: NCT01955200.

Role of endothelial dysfunction in heart failure

Coronary artery disease is a major underlying etiology for heart failure. The role of coronary microvascular disease, and endothelial dysfunction, in the pathophysiology of heart failure is poorly appreciated. Endothelial dysfunction, induced by oxidative stress, contributes to the development of heart failure. Alterations of endothelial function and nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway are involved in the pathophysiology of heart failure with both reduced and preserved ejection fraction. Indeed, an altered endothelium dependent vasodilatation, causing repeated episodes of ischemia/reperfusion, can induce a chronic stunned myocardium with systolic dysfunction and an increased diastolic stiffness with diastolic dysfunction. Moreover, the altered NO-cGMP pathway directly affects myocardial homeostasis. Endothelial dysfunction is associated with worse prognosis and higher rate of cardiovascular events. Potential therapeutic strategies targeting the NO-cGMP pathway in patients with HF will be discussed in this review article. Although clinical data are still inconclusive, the NO-cGMP pathway represents a promising target for therapy.

Induction of homeostatic biological parameters in reward deficiency as a function of an iron-free multi-nutrient complex: Promoting hemoglobinization, aerobic metabolism, viral immuno-competence, and neuroinflammatory regulation

BACKGROUND

A common neurological condition worldwide is Reward Deficiency Syndrome (RDS) leading to both substance and non-substance addictive behaviors, that must be combatted by integrating both central nervous system and peripheral nervous system biological approaches. Integrity of hemoglobin is a crucial determining factor for the overall health functions. Nutrient repletion therapy should be a fundamental strategy to restore the healthy properties of blood. A unique patent-pending iron-free VMP35 formulation was engineered by our laboratory to restore iron-dependent hemoglobin in anemic cells using a proprietary Prodosome® absorption technology. This formulation, containing an array of nano-emulsified botanical ingredients rich in bioflavonoids, strengthens the structural integrity of connective tissues, and potentiates immune competence, cellular aerobic metabolism, and enhances efficient regulation of inflammatory events. We discuss the intricate aspects of strong vs. fragile immunity and consequential inflammatory responses to convey a deeper understanding of the varied and overly complex sequela of immunological behaviors and events. The effect of the VMP35 is mediated through highly absorbable nutritional/nutrigenomic repletion enabling improvements in the systemic set of functional behaviors. In fact, the iron-free VMP35 facilitates a "Systems Biology Approach" which restores hemoglobin status, reverses anaerobic hypoxia, improves competent immune responsivity, and regulates appropriate and controlled activation of general and neuro-inflammatory sequela. Under these pathogenic circumstances, iron-deficiency anemia has been misconceptualized, and a new nosological term, Chronic Anemia Syndrome, is proposed. The comparative therapeutic rationale of Reductionist vs. Systems Biology approaches is also explained in detail.

METHODS

The efficacy of the novel therapeutic iron-free VMP35 liquid nutraceutical is detailed in restoring iron-dependent hemoglobin to RBCs and boosting cellular morphology, viability, and immune competence, thereby reducing the need for prolonging inflammatory sequela.

RESULTS

This was demonstrated in a previous IRB approved multi-subject human study. In addition, two recent case studies report dramatic restorative benefits of nutrient repletion therapy of the VMP35 on subjects having experienced near-fatal events, which confirmed the findings explained in this manuscript.

CONCLUSIONS

This novel iron-free VMP35 modulates an array of homeostatic biological parameters such as enhanced hemoglobinization, aerobic metabolism, viral immuno-competence, and inflammatory regulation. Further research, examining mechanistic and beneficial effects in athletic performance, is in progress. Importantly, during these troubled immune challenging times, modulating an array of homeostatic immunological and inflammatory dysfunctions are tantamount to improved population outcomes.

TRIAL REGISTRATION

The Clinical investigation in a total of 38 subjects was conducted under an Institutional Review Board (IRB) from the Path Foundation in New York, NY (#13-009 April 25, 2013). The two case studies were done at Lancaster General Hospital, Lancaster, PA, and Jefferson University Hospital, Philadelphia, PA, USA. Both studies were retrospectively registered.

A plasma metabonomics study on the therapeutic effects of the Si-miao-yong-an decoction in hyperlipidemic rats

ETHNOPHARMACOLOGICAL RELEVANCE

The Si-miao-yong-an decoction (SMYAD) is a famous traditional Chinese medicinal formula that has been used for centuries in ancient China for treating thromboangiitis obliterans. Because of its long history of use, it has been used to treat patients in China for thousands of years. In recent years, SMYAD has been widely used for treating cardiovascular and endocrine diseases. It was shown to significantly increase high-density lipoprotein-cholesterol levels and reduce total cholesterol and low-density lipoprotein-cholesterol levels in the serum.

AIM OF THE STUDY

Herein, a serum metabonomics approach based on the HPLC-MS/MS method was adopted to evaluate the therapeutic effect of SMYAD on high-fat diet-induced hyperlipidemia, and investigate the mechanisms for treating hyperlipidemia.

MATERIALS AND METHODS

Firstly, the change in body weight, liver histopathology, and serum biochemistry, including that in the levels of hepatotoxicity-related enzymes, oxidative stress indexes, and inflammatory factors were monitored in rats, to evaluate the therapeutic effect of SMYAD on high-fat diet-induced hyperlipidemia. Then, a serum metabolomics approach was applied, to cluster different groups using principle component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), as well as to screen out sensitive and reliable biomarkers. Finally, the metabolic pathways associated with specific biomarkers were analyzed, to understand the possible mechanism underlying the action of SMYAD.

RESULTS

The results indicated that SMYAD had significant anti-hyperlipidemic, anti-oxidant, and anti-inflammatory effects. Based on the results of serum metabolomics analysis, the hyperlipidemic rats showed completely different results compared to the control rats; metabolite profiles of rats from the SMYAD treatment groups showed a trend comparable to those of the normal control group in a dose-dependent manner. Besides, twelve biomarkers associated with pyruvate metabolism, taurine and hypotaurine metabolism, TCA cycle, bile acid metabolism, and glucose metabolism were identified and confirmed, to clarify the mechanism of action of SMYAD.

CONCLUSION

Using metabonomics technology, it was predicted that the therapeutic effects of SMYAD were associated with its anti-oxidation as well as anti-inflammatory activities and the adjustment of the pyruvate, taurine as well as hypotaurine metabolism pathways in the hyperlipidemic state. This study provided evidence regarding the clinical application of SMYAD and thoroughly explored the mechanism underlying the action of this traditional Chinese medicine.

ArrhythmoGenoPharmacoTherapy

This review is focusing on the understanding of various factors and components governing and controlling the occurrence of ventricular arrhythmias including (i) the role of various ion channel-related changes in the action potential (AP), (ii) electrocardiograms (ECGs), (iii) some important arrhythmogenic mediators of reperfusion, and pharmacological approaches to their attenuation. The transmembrane potential in myocardial cells is depending on the cellular concentrations of several ions including sodium, calcium, and potassium on both sides of the cell membrane and active or inactive stages of ion channels. The movements of Na+, K+, and Ca2+ via cell membranes produce various currents that provoke AP, determining the cardiac cycle and heart function. A specific channel has its own type of gate, and it is opening and closing under specific transmembrane voltage, ionic, or metabolic conditions. APs of sinoatrial (SA) node, atrioventricular (AV) node, and Purkinje cells determine the pacemaker activity (depolarization phase 4) of the heart, leading to the surface manifestation, registration, and evaluation of ECG waves in both animal models and humans. AP and ECG changes are key factors in arrhythmogenesis, and the analysis of these changes serve for the clarification of the mechanisms of antiarrhythmic drugs. The classification of antiarrhythmic drugs may be based on their electrophysiological properties emphasizing the connection between basic electrophysiological activities and antiarrhythmic properties. The review also summarizes some important mechanisms of ventricular arrhythmias in the ischemic/reperfused myocardium and permits an assessment of antiarrhythmic potential of drugs used for pharmacotherapy under experimental and clinical conditions.

Repurposing Disulfiram as An Anti-Cancer Agent: Updated Review on Literature and Patents

BACKGROUND

Despite years of success of most anti-cancer drugs, one of the major clinical problems is inherent and acquired resistance to these drugs. Overcoming the drug resistance or developing new drugs would offer promising strategies in cancer treatment. Disulfiram, a drug currently used in the treatment of chronic alcoholism, has been found to have anti-cancer activity.

OBJECTIVE

To summarize the anti-cancer effects of Disulfiram through a thorough patent review.

METHODS

This article reviews molecular mechanisms and recent patents of Disulfiram in cancer therapy.

RESULTS

Several anti-cancer mechanisms of Disulfiram have been proposed, including triggering oxidative stress by the generation of reactive oxygen species, inhibition of the superoxide dismutase activity, suppression of the ubiquitin-proteasome system, and activation of the mitogen-activated protein kinase pathway. In addition, Disulfiram can reverse the resistance to chemotherapeutic drugs by inhibiting the P-glycoprotein multidrug efflux pump and suppressing the activation of NF-kB, both of which play an important role in the development of drug resistance. Furthermore, Disulfiram has been found to reduce angiogenesis because of its metal chelating properties as well as its ability to inactivate Cu/Zn superoxide dismutase and matrix metalloproteinases. Disulfiram has also been shown to inhibit the proteasomes, DNA topoisomerases, DNA methyltransferase, glutathione S-transferase P1, and O6- methylguanine DNA methyltransferase, a DNA repair protein highly expressed in brain tumors. The patents described in this review demonstrate that Disulfiram is useful as an anti-cancer drug.

CONCLUSION

For years the FDA-approved, well-tolerated, inexpensive, orally-administered drug Disulfiram was used in the treatment of chronic alcoholism, but it has recently demonstrated anti-cancer effects in a range of solid and hematological malignancies. Its combination with copper at clinically relevant concentrations might overcome the resistance of many anti-cancer drugs in vitro, in vivo, and in patients.

Chemical Probes for Redox Signaling and Oxidative Stress

SIGNIFICANCE

Cellular reactive oxygen species (ROS) mediate redox signaling cascades that are critical to numerous physiological and pathological processes. Analytical methods to monitor cellular ROS levels and proteomic platforms to identify oxidative post-translational modifications (PTMs) of proteins are critical to understanding the triggers and consequences of redox signaling. Recent Advances: The prevalence and significance of redox signaling has recently been illuminated through the use of chemical probes that allow for sensitive detection of cellular ROS levels and proteomic dissection of oxidative PTMs directly in living cells.

CRITICAL ISSUES

In this review, we provide a comprehensive overview of chemical probes that are available for monitoring ROS and oxidative PTMs, and we highlight the advantages and limitations of these methods.

FUTURE DIRECTIONS

Despite significant advances in chemical probes, the low levels of cellular ROS and low stoichiometry of oxidative PTMs present challenges for accurately measuring the extent and dynamics of ROS generation and redox signaling. Further improvements in sensitivity and ability to spatially and temporally control readouts are essential to fully illuminate cellular redox signaling.

SGLT2 inhibition with empagliflozin attenuates myocardial oxidative stress and fibrosis in diabetic mice heart

Background

Hyperglycaemia associated with myocardial oxidative stress and fibrosis is the main cause of diabetic cardiomyopathy. Empagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor has recently been reported to improve glycaemic control in patients with type 2 diabetes in an insulin-independent manner. The aim of this study was to investigate the effect of empagliflozin on myocardium injury and the potential mechanism in type 2 diabetic KK-Ay mice.

Methods

Thirty diabetic KK-Ay mice were administered empagliflozin (10 mg/kg/day) by oral gavage daily for 8 weeks. After 8 weeks, heart structure and function were evaluated by echocardiography. Oxidants and antioxidants were measured and cardiac fibrosis was analysed using immunohistochemistry, Masson’s trichrome stain and Western blot.

Results

Results showed that empagliflozin improved diabetic myocardial structure and function, decreased myocardial oxidative stress and ameliorated myocardial fibrosis. Further study indicated that empagliflozin suppressed oxidative stress and fibrosis through inhibition of the transforming growth factor β/Smad pathway and activation of Nrf2/ARE signaling.

Conclusions

Glycaemic control with empagliflozin significantly ameliorated myocardial oxidative stress injury and cardiac fibrosis in diabetic mice. Taken together, these results indicate that the empagliflozin is a promising agent for the prevention and treatment of diabetic cardiomyopathy.

The Prediction of Cardiac Events in Patients with Acute ST Segment Elevation Myocardial Infarction: A Meta-analysis of Serum Uric Acid

Objective

The current study aimed to explore the predictive ability of serum uric acid (SUA) in patients suffering from acute ST segment elevation myocardial infarction (STEMI).

Method

PubMed, EMBASE, Cochrane Library, and Medline databases were systematically searched from their respective inceptions to February 2018. Systematic analysis and random-effects meta-analysis of prognostic effects were performed to evaluate STEMI outcomes [i.e., in-hospital mortality, one-year mortality, in-hospital Major Adverse Cardiovascular Events (MACE)] in relation to SUA.

Results

A total of 12 studies (containing 7,735 patients with acute STEMI) were identified (5,562 low SUA patients and 3,173 high SUA patients). Systematic analysis of these studies showed that high SUA patients exhibited a higher incidence of in-hospital MACE (OR, 2.30; P < 0.00001), in-hospital mortality (OR, 3.03; P < 0.0001), and one-year mortality (OR, 2.58; P < 0.00001), compared with low SUA patients.

Conclusions

Acute STEMI patients with high SUA exhibited an elevated incidence rate of in-hospital MACE, in-hospital mortality, and one-year mortality. Further randomized controlled trials will be needed to verify these results.

Evaluation of the association between hyperuricemia and coronary artery disease: A STROBE-compliant article

The aim of the study was to assess the independent contribution of hyperuricemia to coronary artery disease (CAD) confirmed by coronary angiography (CAG), and to explore associations between serum uric acid (SUA) level and CAD.We performed a retrospective cohort study of 5069 patients who underwent CAG. Patients were divided into groups: hyperuricemia (n = 1178) versus nonhyperuricemia (n = 3891) and CAD (n = 3433) versus non-CAD (n = 1636).The incidence of CAD was higher in the hyperuricemia group than in the nonhyperuricemia group (71.5% vs 66.6%, P = .002). Hyperuricemia and CAD were significantly correlated in women (odds ratio = 1.509, 95% confidence interval, 1.106-2.057, P = .009). And there were trends, higher SUA quartiles were associated with higher percentage of CAD (62.3%, 68.0%, 68.9%, and 71.7% for quartiles 1, 2, 3, and 4, respectively, P < .001), and the incidence of 3-vessel disease increased (25.2%, 26.4%, 27.2%, and 31.1% for quartiles 1, 2, 3, and 4, respectively, P = .001) and that of normal vessel decreased (37.7%, 32.0%, 31.1%, and 28.3% for quartiles 1, 2, 3, and 4, respectively, P < .001) across quartiles, these trends were found in female group, but not in male group. The SUA level significantly increased as the number of diseased vessels increased (P < .001).There was an independent correlation between hyperuricemia and CAD in women. A higher SUA level was associated with a higher incidence of 3-vessel disease in women.

Putting xanthine oxidoreductase and aldehyde oxidase on the NO metabolism map: Nitrite reduction by molybdoenzymes

Nitric oxide radical (NO) is a signaling molecule involved in several physiological and pathological processes and a new nitrate-nitrite-NO pathway has emerged as a physiological alternative to the "classic" pathway of NO formation from L-arginine. Since the late 1990s, it has become clear that nitrite can be reduced back to NO under hypoxic/anoxic conditions and exert a significant cytoprotective action in vivo under challenging conditions. To reduce nitrite to NO, mammalian cells can use different metalloproteins that are present in cells to perform other functions, including several heme proteins and molybdoenzymes, comprising what we denominated as the "non-dedicated nitrite reductases". Herein, we will review the current knowledge on two of those "non-dedicated nitrite reductases", the molybdoenzymes xanthine oxidoreductase and aldehyde oxidase, discussing the in vitro and in vivo studies to provide the current picture of the role of these enzymes on the NO metabolism in humans.

A selenoprotein T-derived peptide protects the heart against ischaemia/reperfusion injury through inhibition of apoptosis and oxidative stress

AIM

Selenoprotein T (SelT or SELENOT) is a novel thioredoxin-like enzyme whose genetic ablation in mice results in early embryonic lethality. SelT exerts an essential cytoprotective action during development and after injury through its redox-active catalytic site. This study aimed to determine the expression and regulation of SelT in the mammalian heart in normal and pathological conditions and to evaluate the cardioprotective effect of a SelT-derived peptide, SelT43-52(PSELT) encompassing the redox motif which is key to its function, against ischaemia/reperfusion(I/R) injury.

METHODS

We used the isolated Langendorff rat heart model and different analyses by immunohistochemistry, Western blot and ELISA.

RESULTS

We found that SelT expression is very abundant in embryo but is undetectable in adult heart. However, SelT expression was tremendously increased after I/R. PSELT (5 nmol/L) was able to induce pharmacological post-conditioning cardioprotection as evidenced by a significant recovery of contractility (dLVP) and reduction of infarct size (IS), without changes in cardiac contracture (LVEDP). In contrast, a control peptide lacking the redox site did not confer cardioprotection. Immunoblot analysis showed that PSELT-dependent cardioprotection is accompanied by a significant increase in phosphorylated Akt, Erk-1/2 and Gsk3α-β, and a decrement of p38MAPK. PSELT inhibited the pro-apoptotic factors Bax, caspase 3 and cytochrome c and stimulated the anti-apoptotic factor Bcl-2. Furthermore, PSELT significantly reduced several markers of I/R-induced oxidative and nitrosative stress.

CONCLUSION

These results unravel the role of SelT as a cardiac modulator and identify PSELT as an effective pharmacological post-conditioning agent able to protect the heart after ischaemic injury.

Genetic deletion of CD38 confers post-ischemic myocardial protection through preserved pyridine nucleotides

Following the onset of ischemia/reperfusion (I/R), CD38 activation occurs and is associated with depletion of NAD(P)(H) in the heart as well as myocardial injury and endothelial dysfunction. Studies with pharmacological inhibitors suggest that the NADP+-hydrolyzing ability of CD38 can deplete the NAD(P)(H) pools. However, there is a need for more specific studies on the importance of CD38 and its role in the process of endothelial dysfunction and myocardial injury in the post-ischemic heart. Therefore, experiments were performed in hearts of mice with global gene knockout of CD38. Isolated perfused CD38-/- and wild type (WT) mouse hearts were studied to determine the link between CD38 activation, the levels of NADP(H), endothelial dysfunction, and myocardial injury after I/R. Genetic deletion of CD38 preserves the myocardial and endothelial NADP(H) pools compared to WT. Whole heart BH4 levels in CD38-/- hearts were also preserved. Post-ischemic levels of cGMP were greatly depleted in WT hearts, but preserved to near baseline levels in CD38-/- hearts. The preservation of these metabolite pools in CD38-/- hearts was accompanied by near full recovery of NOS-dependent coronary flow, while in WT hearts, severe impairment of endothelial function and NOS uncoupling occurred with decreased NO and enhanced superoxide generation. CD38-/- hearts also exhibited marked protection against I/R with preserved glutathione levels, increased recovery of left ventricular contractile function, decreased myocyte enzyme release, and decreased infarct size. Thus, CD38 activation causes post-ischemic depletion of NADP(H) within the heart, with severe depletion from the endothelium, resulting in endothelial dysfunction and myocardial injury.

Characterization of CD38 in the major cell types of the heart: endothelial cells highly express CD38 with activation by hypoxia-reoxygenation triggering NAD(P)H depletion

The NAD(P)⁺-hydrolyzing enzyme CD38 is activated in the heart during the process of ischemia and reperfusion, triggering NAD(P)(H) depletion. However, the presence and role of CD38 in the major cell types of the heart are unknown. Therefore, we characterize the presence and function of CD38 in cardiac myocytes, endothelial cells, and fibroblasts. To comprehensively evaluate CD38 in these cells, we measured gene transcription via mRNA, as well as protein expression and enzymatic activity. Endothelial cells strongly expressed CD38, while only low expression was present in cardiac myocytes with intermediate levels in fibroblasts. In view of this high level expression in endothelial cells and the proposed role of CD38 in the pathogenesis of endothelial dysfunction, endothelial cells were subjected to hypoxia-reoxygenation to characterize the effect of this stress on CD38 expression and activity. An activity-based CD38 imaging method and CD38 activity assays were used to characterize CD38 activity in normoxic and hypoxic-reoxygenated endothelial cells, with marked CD38 activation seen following hypoxia-reoxygenation. To test the impact of hypoxia-reoxygenation-induced CD38 activation on endothelial cells, NAD(P)(H) levels and endothelial nitric oxide synthase (eNOS)-derived NO production were measured. Marked NADP(H) depletion with loss of NO and increase in superoxide production occurred following hypoxia-reoxygenation that was prevented by CD38 inhibition or knockdown. Thus, endothelial cells have high expression of CD38 which is activated by hypoxia-reoxygenation triggering CD38-mediated NADP(H) depletion with loss of eNOS-mediated NO generation and increased eNOS uncoupling. This demonstrates the importance of CD38 in the endothelium and explains the basis by which CD38 triggers post-ischemic endothelial dysfunction.

Therapeutic Hypothermia Reduces Oxidative Damage and Alters Antioxidant Defenses after Cardiac Arrest

After cardiac arrest, organ damage consequent to ischemia-reperfusion has been attributed to oxidative stress. Mild therapeutic hypothermia has been applied to reduce this damage, and it may reduce oxidative damage as well. This study aimed to compare oxidative damage and antioxidant defenses in patients treated with controlled normothermia versus mild therapeutic hypothermia during postcardiac arrest syndrome. The sample consisted of 31 patients under controlled normothermia (36°C) and 11 patients treated with 24 h mild therapeutic hypothermia (33°C), victims of in- or out-of-hospital cardiac arrest. Parameters were assessed at 6, 12, 36, and 72 h after cardiac arrest in the central venous blood samples. Hypothermic and normothermic patients had similar S100B levels, a biomarker of brain injury. Xanthine oxidase activity is similar between hypothermic and normothermic patients; however, it decreases posthypothermia treatment. Xanthine oxidase activity is positively correlated with lactate and S100B and inversely correlated with pH, calcium, and sodium levels. Hypothermia reduces malondialdehyde and protein carbonyl levels, markers of oxidative damage. Concomitantly, hypothermia increases the activity of erythrocyte antioxidant enzymes superoxide dismutase, glutathione peroxidase, and glutathione S-transferase while decreasing the activity of serum paraoxonase-1. These findings suggest that mild therapeutic hypothermia reduces oxidative damage and alters antioxidant defenses in postcardiac arrest patients.

Luteolinidin Protects the Postischemic Heart through CD38 Inhibition with Preservation of NAD(P)(H)

We recently showed that ischemia/reperfusion (I/R) of the heart causes CD38 activation with resultant depletion of the cardiac NADP(H) pool, which is most marked in the endothelium. This NADP(H) depletion was shown to limit the production of nitric oxide by endothelial nitric oxide synthase (eNOS), which requires NADPH for nitric oxide production, resulting in greatly altered endothelial function. Therefore, intervention with CD38 inhibitors could reverse postischemic eNOS-mediated endothelial dysfunction. Here, we evaluated the potency of the CD38 inhibitor luteolinidin, an anthocyanidin, at blocking CD38 activity and preserving endothelial and myocardial function in the postischemic heart. Initially, we characterized luteolinidin as a CD38 inhibitor in vitro to determine its potency and mechanism of inhibition. We then tested luteolinidin in the ex vivo isolated heart model, where we determined luteolinidin uptake with aqueous and liposomal delivery methods. Optimal delivery methods were then further tested to determine the effect of luteolinidin on postischemic NAD(P)(H) and tetrahydrobiopterin levels. Finally, through nitric oxide synthase-dependent coronary flow and left ventricular functional measurements, we evaluated the efficacy of luteolinidin to protect vascular and contractile function, respectively, after I/R. With enhanced postischemic preservation of NADPH and tetrahydrobiopterin, there was a dose-dependent effect of luteolinidin on increasing recovery of endothelium-dependent vasodilatory function, as well as enhancing the recovery of left ventricular contractile function with increased myocardial salvage. Thus, luteolinidin is a potent CD38 inhibitor that protects the heart against I/R injury with preservation of eNOS function and prevention of endothelial dysfunction.

The Nrf2/Keap1/ARE Pathway and Oxidative Stress as a Therapeutic Target in Type II Diabetes Mellitus

Despite improvements in awareness and treatment of type II diabetes mellitus (TIIDM), this disease remains a major source of morbidity and mortality worldwide, and prevalence continues to rise. Oxidative damage caused by free radicals has long been known to contribute to the pathogenesis and progression of TIIDM and its complications. Only recently, however, has the role of the Nrf2/Keap1/ARE master antioxidant pathway in diabetic dysfunction begun to be elucidated. There is accumulating evidence that this pathway is implicated in diabetic damage to the pancreas, heart, and skin, among other cell types and tissues. Animal studies and clinical trials have shown promising results suggesting that activation of this pathway can delay or reverse some of these impairments in TIIDM. In this review, we outline the role of oxidative damage and the Nrf2/Keap1/ARE pathway in TIIDM, focusing on current and future efforts to utilize this relationship as a therapeutic target for prevention, prognosis, and treatment of TIID.

Generation of hydroxyl radicals and singlet oxygen during oxidation of rhododendrol and rhododendrol-catechol

The generation of hydroxyl radicals and singlet oxygen during the oxidation of 4-(4-hydroxyphenyl)-2-butanol (rhododendrol) and 4-(3,4-dihydroxyphenyl)-2-butanol (rhododendrol-catechol) with mushroom tyrosinase in a phosphate buffer (pH 7.4) was examined as the model for the reactive oxygen species generation via the two rhododendrol compounds in melanocytes. The reaction was performed in the presence of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) spin trap reagents for hydroxyl radical or 2,2,6,6-tetramethyl-4-piperidone (4-oxo-TEMP), an acceptor of singlet oxygen, and their electron spin resonances were measured. An increase in the electron spin resonances signal attributable to the adduct of DMPO reacting with the hydroxyl radical and that of 4-oxo-TEMP reacting with singlet oxygen was observed during the tyrosinase-catalyzed oxidation of rhododendrol and rhododendrol-catechol, indicating the generation of hydroxyl radical and singlet oxygen. Moreover, hydroxyl radical generation was also observed in the autoxidation of rhododendrol-catechol. We show that generation of intermediates during tyrosinase-catalyzed oxidation of rhododendrol enhances oxidative stress in melanocytes.

Measurement of Reactive Oxygen Species, Reactive Nitrogen Species, and Redox-Dependent Signaling in the Cardiovascular System: A Scientific Statement From the American Heart Association

Reactive oxygen species and reactive nitrogen species are biological molecules that play important roles in cardiovascular physiology and contribute to disease initiation, progression, and severity. Because of their ephemeral nature and rapid reactivity, these species are difficult to measure directly with high accuracy and precision. In this statement, we review current methods for measuring these species and the secondary products they generate and suggest approaches for measuring redox status, oxidative stress, and the production of individual reactive oxygen and nitrogen species. We discuss the strengths and limitations of different methods and the relative specificity and suitability of these methods for measuring the concentrations of reactive oxygen and reactive nitrogen species in cells, tissues, and biological fluids. We provide specific guidelines, through expert opinion, for choosing reliable and reproducible assays for different experimental and clinical situations. These guidelines are intended to help investigators and clinical researchers avoid experimental error and ensure high-quality measurements of these important biological species.

Antioxidant strategies in respiratory medicine

Pulmonary oxidant stress plays an important pathogenetic role in disease conditions including acute lung injury/adult respiratory distress syndrome (ALI/ARDS), hyperoxia, ischemia-reperfusion, sepsis, radiation injury, lung transplantation, COPD, and inflammation. Reactive oxygen species (ROS), released from activated macrophages and leukocytes or formed in the pulmonary epithelial and endothelial cells, damage the lungs and initiate cascades of pro-inflammatory reactions propagating pulmonary and systemic stress. Diverse molecules including small organic compounds (e.g. gluthatione, tocopherol (vitamin E), flavonoids) serve as natural antioxidants that reduce oxidized cellular components, decompose ROS and detoxify toxic oxidation products. Antioxidant enzymes can either facilitate these antioxidant reactions (e.g. peroxidases using glutathione as a reducing agent) or directly decompose ROS (e.g. superoxide dismutases [SOD] and catalase). Many antioxidant agents are being tested for treatment of pulmonary oxidant stress. The administration of small antioxidants via the oral, intratracheal and vascular routes for the treatment of short- and long-term oxidant stress showed rather modest protective effects in animal and human studies. Intratracheal and intravascular administration of antioxidant enzymes are being currently tested for the treatment of acute oxidant stress. For example, intratracheal administration of recombinant human SOD is protective in premature infants exposed to hyperoxia. However, animal and human studies show that more effective delivery of drugs to cells experiencing oxidant stress is needed to improve protection. Diverse delivery systems for antioxidants including liposomes, chemical modifications (e.g. attachment of masking pegylated [PEG]-groups) and coupling to affinity carriers (e.g. antibodies against cellular adhesion molecules) are being employed and currently tested, mostly in animal and, to a limited extent, in humans, for the treatment of oxidant stress. Further studies are needed, however, in order to develop and establish effective applications of pulmonary antioxidant interventions useful in clinical practice. Although beyond the scope of this review, antioxidant gene therapies may eventually provide a strategy for the management of subacute and chronic pulmonary oxidant stress.

Uric acid and high-residual platelet reactivity in patients treated with clopidogrel or ticagrelor

BACKGROUND AND AIM

High residual platelet reactivity (HRPR) is still an important challenge, despite the advent of new potent ADP-antagonists. Therefore it is of extreme importance to identify factors that can influence platelet activation. Serum uric acid (SUA) has been largely addressed in the past as a possible risk factor for coronary artery disease, with a possible association with platelets hyperreactivity. So far no studies have assessed the role of serum uric acid on the response to dual antiplatelet therapy. Therefore, the aim of our study was to evaluate the impact of uric acid levels on platelet function in patients treated with dual antiplatelet therapy (DAPT) with clopidogrel or ticagrelor.

METHODS AND RESULTS

We scheduled for platelet function assessment at 30-90 days post-discharge patients treated with DAPT (ASA + clopidogrel or ticagrelor) for an ACS or elective percutaneous coronary intervention (PCI). Platelet function was assessed by whole blood impedance aggregometry (Multiplate(®)-Roche Diagnostics AG), HRPR was considered for ASPI test >862 AU(∗)min (for ASA) and ADP test values ≥417 AU* min (for ADP-antagonists).

RESULTS

We included a total of 493 patients (262 were on ASA and clopidogrel and 231 on ASA and ticagrelor). Patients were divided according to quartiles of serum uric acid levels measured at the time of platelet aggregation assessment (Group 1 <4.6 mg/dL, n = 114; Group 2, 4.7-5.8 mg/dL, n = 133; Group 3, 5.9-6.8 mg/dL, n = 124; Group 4, >6.9, n = 122). Patients with higher uric acid levels were older, more often smokers, with history of hypertension and previous coronary artery bypass surgery and renal failure and were more often on therapy with diuretics at admission. Patients with higher SUA had higher triglycerides and fibrinogen. Uric acid levels did not influence ASPI, COL, TRAP and ADP tests. High residual platelet reactivity (HRPR) was observed in 1.5% of patients treated with ASA, with no difference according to SUA quartiles (p = 0.60), confirmed at multivariate analysis after correction for baseline confounders (adjusted OR[95%CI] = 1.05 [0.44-2.52], p = 0.90). HRPR for ADP-antagonists was observed in 23.6% of patients, with no difference according to SUA quartiles (p = 0.47); this result was confirmed also after correction for baseline confounders (adjusted OR[95%CI] = 1.04 [0.84-1.28], p = 0.73). Moreover, no association was found between HRPR and uric acid levels both among patients treated with clopidogrel (p = 0.35) or ticagrelor (p = 0.74), that was confirmed after correction for baseline confounding factors (adjusted OR[95%CI] = 1.18 [0.90-1.55], p = 0.23) and (adjusted OR[95%CI] = 0.96 [0.63-1.47], p = 0.85). The absence of association between SUA and platelet reactivity was confirmed at linear regression analysis both with clopidogrel (r = 0.03, p = 0.55) or ticagrelor (r = -0.01, p = 0.85).

CONCLUSION

This is the first large study showing that in patients receiving DAPT, uric acid levels do not influence response to ticagrelor and clopidogrel or the effectiveness of ASA.

Chimeric Aptamer-Gelatin Hydrogels as an Extracellular Matrix Mimic for Loading Cells and Growth Factors

It is important to synthesize materials to recapitulate critical functions of biological systems for a variety of applications such as tissue engineering and regenerative medicine. The purpose of this study was to synthesize a chimeric hydrogel as a promising extracellular matrix (ECM) mimic using gelatin, a nucleic acid aptamer, and polyethylene glycol. This hydrogel had a macroporous structure that was highly permeable for fast molecular transport. Despite its high permeability, it could strongly sequester and sustainably release growth factors with high bioactivity. Notably, growth factors retained in the hydrogel could maintain ∼ 50% bioactivity during a 14-day release test. It also provided cells with effective binding sites, which led to high efficiency of cell loading into the macroporous hydrogel matrix. When cells and growth factors were coloaded into the chimeric hydrogel, living cells could still be observed by day 14 in a static serum-reduced culture condition. Thus, this chimeric aptamer-gelatin hydrogel constitutes a promising biomolecular ECM mimic for loading cells and growth factors.

Impact of sex on uric acid levels and its relationship with the extent of coronary artery disease: A single-centre study

BACKGROUND

Serum uric acid (SUA) elevation has been largely addressed in the past as a possible risk factor for cardiovascular disease. However, uric acid has not clearly emerged as independent risk factor for coronary artery disease. Several studies in literature have assessed sex-related differences in the association between elevated SUA levels and cardiovascular events with conflicting results. Therefore, aim of the current study was to evaluate the relationship between uric acid levels and the extent of coronary artery disease in male and female patients undergoing coronary angiography.

METHODS

Our population is represented by 3520 consecutive patients undergoing coronary angiography from March 2007 to October 2012. Patients were divided according to Tertiles of SUA (Males, Group 1, ≤5.5 mg/dL-0.33 mmol/mol, n = 762, Group 2, 5.5-6.8 mg/dL-0.33-0.40 mmol/mol, n = 829 and Group 3 ≥6.8 mg/dL-0.40 mmol/mol, n = 851), (Females, Group 1, ≤4.8 mg/dL-0.28 mmol/mol, n = 349, Group 2, 4.8-6.3 mg/dL-0.28-0.37 mmol/mol, n = 359 and Group 3 ≥ 6.3 mg/dL-0.37 mmol/mol, n = 370). Fasting samples were collected for uric acid levels assessment. Coronary disease was defined for at least 1 vessel stenosis >50% as evaluated by QCA. Severe coronary disease was defined as three-vessel disease and/or left main disease.

RESULTS

Among 3520 patients, we identified 2442 men (69.4%) and 1078 women (30.6%). Males had higher levels of uric acid than women (6.33 ± 1.7 vs 5.8 ± 1.9 - p < 0.001). The association between elevated uric acid (≥7 mg/dl or 0.42 mmol/l) and male gender was confirmed after correction for baseline confounding factors (Adjusted OR = 1.28 [1.01-1.62], p = 0.004). Males displayed a significantly higher prevalence and extent of CAD (p < 0.001) and more complex coronary lesions (p < 0.001). However, no significant relationship was observed between uric acid and CAD (Adjusted OR [95%CI] = 0.90 [0.76-1.06], p = 0.22) or severe CAD (Adjusted OR [95%CI] = 0.89 [0.79-1.01], p = 0.08). Among females, higher SUA levels were significantly associated with higher prevalence of severe CAD (p < 0.001) (Adjusted OR [95% CI] = 1.29 [1.03-1.62], p = 0.03).

CONCLUSION

Our study showed that uric acid levels are significantly higher in men. However, high uric acid levels are associated with severe CAD only in women. Future large studies are certainly needed to confirm our findings and to evaluate the effects of SUA lowering therapies on cardiovascular prevention and outcome, especially in women.

Prognostic value of serum uric acid: new-onset in and out-of-office hypertension and long-term mortality

OBJECTIVE

Serum uric acid (SUA) has been associated with an increased cardiovascular risk, but no conclusive evidence exists on whether it is an independent risk factor or a reflection of other risk factors to which it is related. We examined the relationship of SUA with a number of cardiovascular variables [including risk factors never evaluated before, such as organ damage and out-of-office blood pressure (BP)], as well as its prognostic relevance in the population.

METHODS

In 2045 participants of the Pressioni Arteriose Monitorate E Loro Associazioni study, we measured, along with SUA, metabolic, renal, and anthropometric variables, left-ventricular mass index, and office, home and ambulatory BP. Cardiovascular and all-cause mortality was assessed over a 16-year follow-up period, and measurements were repeated 10 years after the initial data collection.

RESULTS

Baseline SUA had a near-normal distribution, with a mean value of 4.9 ± 1.3 (SD) mg/dl and a significant direct relationship with BP and metabolic variables, serum creatinine and left-ventricular mass index. It was among the factors independently predicting new-onset home and ambulatory hypertension, the increased risk of developing these conditions for 1  mg/dl increase of SUA after adjustment for all available potential confounders being 34 and 29%, respectively (P = 0.015 and P = 0.014). An increase in SUA of 1  mg/dl also independently predicted cardiovascular and all-cause mortality, the fully adjusted increase in risk being 22% (P = 0.03) and 12% (P = 0.04), respectively.

CONCLUSION

In the general population of the Pressioni Arteriose Monitorate E Loro Associazioni study, SUA correlated with a number of cardiovascular risk factors. Nevertheless, it independently predicts new-onset out-of-office hypertension, and long-term cardiovascular and all-cause mortality.

Nitrite reductase activity of rat and human xanthine oxidase, xanthine dehydrogenase, and aldehyde oxidase: evaluation of their contribution to NO formation in vivo

Nitrite is presently considered a NO "storage form" that can be made available, through its one-electron reduction, to maintain NO formation under hypoxia/anoxia. The molybdoenzymes xanthine oxidase/dehydrogenase (XO/XD) and aldehyde oxidase (AO) are two of the most promising mammalian nitrite reductases, and in this work, we characterized NO formation by rat and human XO/XD and AO. This is the first characterization of human enzymes, and our results support the employment of rat liver enzymes as suitable models of the human counterparts. A comprehensive kinetic characterization of the effect of pH on XO and AO-catalyzed nitrite reduction showed that the enzyme's specificity constant for nitrite increase 8-fold, while the Km(NO2(-)) decrease 6-fold, when the pH decreases from 7.4 to 6.3. These results demonstrate that the ability of XO/AO to trigger NO formation would be greatly enhanced under the acidic conditions characteristic of ischemia. The dioxygen inhibition was quantified, and the Ki(O2) values found (24.3-48.8 μM) suggest that in vivo NO formation would be fine-tuned by dioxygen availability. The potential in vivo relative physiological relevance of XO/XD/AO-dependent pathways of NO formation was evaluated using HepG2 and HMEC cell lines subjected to hypoxia. NO formation by the cells was found to be pH-, nitrite-, and dioxygen-dependent, and the relative contribution of XO/XD plus AO was found to be as high as 50%. Collectively, our results supported the possibility that XO/XD and AO can contribute to NO generation under hypoxia inside a living human cell. Furthermore, the molecular mechanism of XO/AO-catalyzed nitrite reduction was revised.

Measurement and characterization of superoxide generation from xanthine dehydrogenase: a redox-regulated pathway of radical generation in ischemic tissues

The enzyme xanthine oxidoreductase (XOR) is an important source of oxygen free radicals and related postischemic injury. Xanthine dehydrogenase (XDH), the major form of XOR in tissues, can be converted to xanthine oxidase (XO) by oxidation of sulfhydryl residues or by proteolysis. The conversion of XDH to XO has been assumed to be required for radical generation and tissue injury. It is also possible that XDH could generate significant quantities of superoxide, ^•O₂^–, for cellular signaling or injury; however, this possibility and its potential ramifications have not been previously considered. To unambiguously determine if XDH can be a significant source of ^•O₂^–, experiments were performed to measure and characterize ^•O₂^– generation using XDH from chicken liver that is locked in the dehydrogenase conformation. Electron paramagnetic resonance spin trapping experiments with 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide demonstrated that XDH in the presence of xanthine produces significant amounts of ^•O₂^–. NAD⁺ and NADH inhibited the generation of ^•O₂^– from XDH in a dose-dependent manner, with NAD⁺ exhibiting stronger inhibition than NADH at low physiological concentrations. Decreased amounts of NAD⁺ and NADH, which occur during and following tissue ischemia, enhanced the generation of ^•O₂^– from XDH in the presence of xanthine. It was observed that XDH-mediated oxygen radical generation markedly depressed Ca²⁺-ATPase activity of isolated sarcoplasmic reticulum vesicles from cardiac muscle, and this was modulated by NAD⁺ and NADH. Thus, XDH can be an important redox-regulated source of ^•O₂^– generation in ischemic tissue, and conversion to XO is not required to activate radical formation and subsequent tissue injury.

Hypoxia and reoxygenation induce endothelial nitric oxide synthase uncoupling in endothelial cells through tetrahydrobiopterin depletion and S-glutathionylation

Ischemia-reperfusion injury is accompanied by endothelial hypoxia and reoxygenation that trigger oxidative stress with enhanced superoxide generation and diminished nitric oxide (NO) production leading to endothelial dysfunction. Oxidative depletion of the endothelial NO synthase (eNOS) cofactor tetrahydrobiopterin can trigger eNOS uncoupling, in which the enzyme generates superoxide rather than NO. Recently, it has also been shown that oxidative stress can induce eNOS S-glutathionylation at critical cysteine residues of the reductase site that serves as a redox switch to control eNOS coupling. While superoxide can deplete tetrahydrobiopterin and induce eNOS S-glutathionylation, the extent of and interaction between these processes in the pathogenesis of eNOS dysfunction in endothelial cells following hypoxia and reoxygenation remain unknown. Therefore, studies were performed on endothelial cells subjected to hypoxia and reoxygenation to determine the severity of eNOS uncoupling and the role of cofactor depletion and S-glutathionylation in this process. Hypoxia and reoxygenation of aortic endothelial cells triggered xanthine oxidase-mediated superoxide generation, causing both tetrahydrobiopterin depletion and S-glutathionylation with resultant eNOS uncoupling. Replenishing cells with tetrahydrobiopterin along with increasing intracellular levels of glutathione greatly preserved eNOS activity after hypoxia and reoxygenation, while targeting either mechanism alone only partially ameliorated the decrease in NO. Endothelial oxidative stress, secondary to hypoxia and reoxygenation, uncoupled eNOS with an altered ratio of oxidized to reduced glutathione inducing eNOS S-glutathionylation. These mechanisms triggered by oxidative stress combine to cause eNOS dysfunction with shift of the enzyme from NO to superoxide production. Thus, in endothelial reoxygenation injury, normalization of both tetrahydrobiopterin levels and the glutathione pool are needed for maximal restoration of eNOS function and NO generation.

Uric acid and risk of periprocedural myocardial infarction in patients undergoing percutaneous coronary intervention

BACKGROUND

Periprocedural myocardial infarction still occurs in patients undergoing percutaneous coronary intervention. However, very little is known about the role of biomarkers possibly predicting this complication. Serum uric acid has been associated with enhanced inflammatory status, higher thrombotic risk and poorer outcome after percutaneous coronary intervention. We therefore, evaluated the association between uric acid levels and periprocedural myocardial infarction in patients undergoing percutaneous coronary intervention.

METHODS

We evaluated 1272 consecutive patients undergoing percutaneous coronary intervention. We measured myonecrosis biomarkers at intervals from 8 to 48 h after percutaneous coronary intervention. Periprocedural myonecrosis was defined as a troponin I increase by 3 times the upper limit normal (ULN) or by 50% of an elevated baseline value and periprocedural myocardial infarction as creatine kinase-Myocardial Band increase by 3 times the ULN or 50% of baseline.

RESULTS

Patients were divided according to tertile values of uric acid (< 5.40, ≥ 6.70 mg/dL). Serum uric acid was related to age, male gender, hypertension, smoking, renal failure (p < 0.001), previous coronary artery bypass grafts (p = 0.05), therapy with ACE inhibitors (p = 0.001) and diuretics (p < 0.001), glycaemia (p = 0.001), creatinine (p < 0.001), haemoglobin (p = 0.002) and white blood cells (p = 0.02). Serum uric acid was inversely related to type C lesions (p = 0.03) and coronary thrombus (p = 0.02). SUA did not affect the risk of periprocedural myocardial infarction (p = 0.29; adjusted odds ratio = 1.11[0.93-1.32], p = 0.26) or periprocedural myonecrosis (p = 0.97; adjusted odds ratio = 0.99[0.86-1.14], p = 0.89). Results were confirmed at subgroup analyses of higher-risk subsets of patients.

CONCLUSION

This is the first large study showing that serum uric acid is not associated with an increase in the risk of periprocedural myocardial infarction in patients undergoing percutaneous coronary revascularization.

Impact of diabetes on uric acid and its relationship with the extent of coronary artery disease and platelet aggregation: a single-centre cohort study

BACKGROUND

Serum uric acid (SUA) elevation has been associated with the main determinants of atherosclerosis and metabolic syndrome, although an independent relationship between SUA and coronary artery disease (CAD) has never been confirmed. Recent reports suggested a central role of SUA in diabetic patients, possibly being an early marker of impaired glucose metabolism and best predicting the risk of cardiovascular events in these patients. Aim of current study was to evaluate the relationship between diabetes and uric acid and its association with the extent of CAD and platelet aggregation among diabetics.

METHODS

In diabetic patients undergoing coronary angiography, fasting samples were collected for uric acid levels assessment. Coronary disease was defined for at least 1 vessel stenosis>50% as evaluated by QCA.

RESULTS

Diabetes was observed in 1173 out of 3280 (35.7%) diabetes was related to age, hypercholesterolemia, hypertension, BMI, renal failure, previous MI or coronary revascularization (p<0.001, respectively) and smoking (p=0.001). Diabetics were more frequently treated with ACE-inhibitors, ARBs, b-blockers, calcium-antagonists, diuretics, statins (p<0.001, respectively), and ASA (p=0.004). Diabetics displayed higher glycemia and HbA1c (p<0.001), higher creatinine and triglycerides (p<0.001) but lower total and HDL cholesterol (p<0.001) and haemoglobin (p<0.001). No significant difference was found in SUA levels between diabetic and non diabetic patients (p=0.09). In fact, we identified age, renal failure, hypertension, smoking, BMI, use of diuretics, statins, haemoglobin, triglycerides and HDL cholesterol levels as independent predictors of higher levels of uric acid (3rd tertile,≥6.7mg/dl or 0.39mmol/l). Among diabetic patients, no relationship was found between uric acid and the extent of coronary artery disease (p=0.27; adjusted OR [95%CI]=0.93 [0.76-1.1], p=0.48), or severe (LM-trivessel) CAD (P=0.05; adjusted OR [95%CI]=1.01 [0.86-1.18], p=0.94). Furthermore, SUA levels did not influence platelet aggregation.

CONCLUSION

Ageing, BMI, renal failure, hypertension, smoking, use of statins and diuretics, haemoglobin, HDL cholesterol and tryglicerides levels but not diabetes or glycemic control are independent predictors of hyperuricemia. Among diabetic patients, higher SUA is not independently associated with the extent of CAD or with platelet aggregation.

The roles of reactive oxygen species and autophagy in mediating the tolerance of tumor cells to cycling hypoxia

Tumor hypoxia (low oxygenation) causes treatment resistance and poor patient outcome. A substantial fraction of tumor cells experience cycling hypoxia, characterized by transient episodes of hypoxia and reoxygenation. These cells are under a unique burden of stress, mediated by excessive production of reactive oxygen species (ROS). Cellular components damaged by ROS can be cleared by autophagy, rendering cycling hypoxic tumor cells particularly vulnerable to inhibition of autophagy and its upstream regulatory pathways. Activation of the PERK-mediated signaling arm of the unfolded protein response during hypoxia plays a critical role in the defense against ROS, both by stimulating glutathione synthesis pathways and through promoting autophagy.