Cysteine hydropersulfide reduces lipid peroxidation and protects against myocardial ischaemia-reperfusion injury - Are endogenous persulfides mediators of ischaemic preconditioning?

Earlier studies revealed the presence of cysteine persulfide (CysSSH) and related polysulfide species in various mammalian tissues. CysSSH has both antioxidant and oxidant properties, modulates redox-dependent signal transduction and has been shown to mitigate oxidative stress. However, its functional relevance in the setting of myocardial ischaemia-reperfusion injury (IRI) remains unknown. The present study was undertaken to (1) study the dynamics of production and consumption of persulfides under normoxic and hypoxic conditions in the heart, and (2) determine whether exogenous administration of the CysSSH donor, cysteine trisulfide (Cys-SSS-Cys) at the onset of reperfusion rescues functional impairment and myocardial damage by interfering with lipid peroxidation. Utilising a well-established ex vivo Langendorff murine model, we here demonstrate that endogenous tissue concentrations of CysSSH are upregulated when oxygen supply is compromised (global myocardial ischaemia) and rapidly restored to baseline levels upon reperfusion, suggestive of active regulation. In a separate set of experiments, exogenous administration of Cys-SSS-Cys for 10 min at the onset of reperfusion was found to decrease malondialdehyde (MDA) concentrations, formation of 4-hydroxynonenal (4-HNE) protein adducts and rescue the heart from injury. Cys-SSS-Cys also restored post-ischaemic cardiac function, improving both coronary flow and left ventricular developed pressure (LVDP). Taken together, these results support the notion that endogenous CysSSH plays an important role as a "redox preconditioning" agent to combat the oxidative insult in myocardial IRI.

Evaluation of Acute Supplementation With the Ketone Ester (R)-3-Hydroxybutyl-(R)-3-Hydroxybutyrate (deltaG) in Healthy Volunteers by Cardiac and Skeletal Muscle 31P Magnetic Resonance Spectroscopy.

In this acute intervention study, we investigated the potential benefit of ketone supplementation in humans by studying cardiac phosphocreatine to adenosine-triphosphate ratios (PCr/ATP) and skeletal muscle PCr recovery using phosphorus magnetic resonance spectroscopy (31P-MRS) before and after ingestion of a ketone ester drink. We recruited 28 healthy individuals: 12 aged 23-70 years for cardiac 31P-MRS, and 16 aged 60-75 years for skeletal muscle 31P-MRS. Baseline and post-intervention resting cardiac and dynamic skeletal muscle 31P-MRS scans were performed in one visit, where 25 g of the ketone monoester, deltaG®, was administered after the baseline scan. Administration was timed so that post-intervention 31P-MRS would take place 30 min after deltaG® ingestion. The deltaG® ketone drink was well-tolerated by all participants. In participants who provided blood samples, post-intervention blood glucose, lactate and non-esterified fatty acid concentrations decreased significantly (-28.8%, p ≪ 0.001; -28.2%, p = 0.02; and -49.1%, p ≪ 0.001, respectively), while levels of the ketone body D-beta-hydroxybutyrate significantly increased from mean (standard deviation) 0.7 (0.3) to 4.0 (1.1) mmol/L after 30 min (p ≪ 0.001). There were no significant changes in cardiac PCr/ATP or skeletal muscle metabolic parameters between baseline and post-intervention. Acute ketone supplementation caused mild ketosis in blood, with drops in glucose, lactate, and free fatty acids; however, such changes were not associated with changes in 31P-MRS measures in the heart or in skeletal muscle. Future work may focus on the effect of longer-term ketone supplementation on tissue energetics in groups with compromised mitochondrial function.

miRNAs as novel immunoregulators in cancer.

The immune system is a well-known vital regulator of tumor growth, and one of the main hallmarks of cancer is evading the immune system. Immune system deregulation can lead to immune surveillance evasion, sustained cancer growth, proliferation, and metastasis. Tumor-mediated disruption of the immune system is accomplished by different mechanisms that involve extensive crosstalk with the immediate microenvironment, which includes endothelial cells, immune cells, and stromal cells, to create a favorable tumor niche that facilitates the development of cancer. The essential role of non-coding RNAs such as microRNAs (miRNAs) in the mechanism of cancer cell immune evasion has been highlighted in recent studies. miRNAs are small non-coding RNAs that regulate a wide range of post-transcriptional gene expression in a cell. Recent studies have focused on the function that miRNAs play in controlling the expression of target proteins linked to immune modulation. Studies show that miRNAs modulate the immune response in cancers by regulating the expression of different immune-modulatory molecules associated with immune effector cells, such as macrophages, dendritic cells, B-cells, and natural killer cells, as well as those present in tumor cells and the tumor microenvironment. This review explores the relationship between miRNAs, their altered patterns of expression in tumors, immune modulation, and the functional control of a wide range of immune cells, thereby offering detailed insights on the crosstalk of tumor-immune cells and their use as prognostic markers or therapeutic agents.

The unspoken benefit of participation in a clinical trial.

BACKGROUND: Publicly funded trials do not usually offer financial incentives to volunteers. An intensive level of medical care could act as an additional motivator for participation. Our aim was to establish whether patients may draw any clinical benefit from volunteering in a clinical trial. METHODS: We analysed the recruitment process of a phase II randomised controlled trial, the Inorganic Nitrate in Angina Study. RESULTS: Two-hundred and thirteen patients with a history of stable angina and who had been under at least annual primary care review were screened for participation by history taking, examination, 12-lead electrocardiography, treadmill test and echocardiography. Thirty-five (16.4%) patients were found to have significant unstable or new clinical pathology, requiring urgent clinical attention. We identified 17 (7.9%) patients with unstable angina. Furthermore, we found new undiagnosed pathologies: amyloidosis in two (0.9%), hypertrophic cardiomyopathy in two (0.9%), left ventricular systolic dysfunction (ejection fraction <45%) in three (1.4%), left ventricular thrombus in one (0.4%), significant valvular disease in five (2.4%) and arrhythmias in six (2.8%). CONCLUSION: Compared with routine care, patients screened for a clinical trial may come under an increased level of scrutiny that may affect their clinical management. This may act as additional motivator to attract patients to future studies.

Role of NAD+ in regulating cellular and metabolic signaling pathways.

BACKGROUND: Nicotinamide adenine dinucleotide (NAD+), a critical coenzyme present in every living cell, is involved in a myriad of metabolic processes associated with cellular bioenergetics. For this reason, NAD+ is often studied in the context of aging, cancer, and neurodegenerative and metabolic disorders. SCOPE OF REVIEW: Cellular NAD+ depletion is associated with compromised adaptive cellular stress responses, impaired neuronal plasticity, impaired DNA repair, and cellular senescence. Increasing evidence has shown the efficacy of boosting NAD+ levels using NAD+ precursors in various diseases. This review provides a comprehensive understanding into the role of NAD+ in aging and other pathologies and discusses potential therapeutic targets. MAJOR CONCLUSIONS: An alteration in the NAD+/NADH ratio or the NAD+ pool size can lead to derailment of the biological system and contribute to various neurodegenerative disorders, aging, and tumorigenesis. Due to the varied distribution of NAD+/NADH in different locations within cells, the direct role of impaired NAD+-dependent processes in humans remains unestablished. In this regard, longitudinal studies are needed to quantify NAD+ and its related metabolites. Future research should focus on measuring the fluxes through pathways associated with NAD+ synthesis and degradation.

Insights Into the Role of CircRNAs: Biogenesis, Characterization, Functional, and Clinical Impact in Human Malignancies.

Circular RNAs (circRNAs) are an evolutionarily conserved novel class of non-coding endogenous RNAs (ncRNAs) found in the eukaryotic transcriptome, originally believed to be aberrant RNA splicing by-products with decreased functionality. However, recent advances in high-throughput genomic technology have allowed circRNAs to be characterized in detail and revealed their role in controlling various biological and molecular processes, the most essential being gene regulation. Because of the structural stability, high expression, availability of microRNA (miRNA) binding sites and tissue-specific expression, circRNAs have become hot topic of research in RNA biology. Compared to the linear RNA, circRNAs are produced differentially by backsplicing exons or lariat introns from a pre-messenger RNA (mRNA) forming a covalently closed loop structure missing 3' poly-(A) tail or 5' cap, rendering them immune to exonuclease-mediated degradation. Emerging research has identified multifaceted roles of circRNAs as miRNA and RNA binding protein (RBP) sponges and transcription, translation, and splicing event regulators. CircRNAs have been involved in many human illnesses, including cancer and neurodegenerative disorders such as Alzheimer's and Parkinson's disease, due to their aberrant expression in different pathological conditions. The functional versatility exhibited by circRNAs enables them to serve as potential diagnostic or predictive biomarkers for various diseases. This review discusses the properties, characterization, profiling, and the diverse molecular mechanisms of circRNAs and their use as potential therapeutic targets in different human malignancies.

Tumor microenvironment: an evil nexus promoting aggressive head and neck squamous cell carcinoma and avenue for targeted therapy.

Head and neck squamous cell carcinoma (HNSCC) is a very aggressive disease with a poor prognosis for advanced-stage tumors. Recent clinical, genomic, and cellular studies have revealed the highly heterogeneous and immunosuppressive nature of HNSCC. Despite significant advances in multimodal therapeutic interventions, failure to cure and recurrence are common and account for most deaths. It is becoming increasingly apparent that tumor microenvironment (TME) plays a critical role in HNSCC tumorigenesis, promotes the evolution of aggressive tumors and resistance to therapy, and thereby adversely affects the prognosis. A complete understanding of the TME factors, together with the highly complex tumor-stromal interactions, can lead to new therapeutic interventions in HNSCC. Interestingly, different molecular and immune landscapes between HPV+ve and HPV-ve (human papillomavirus) HNSCC tumors offer new opportunities for developing individualized, targeted chemoimmunotherapy (CIT) regimen. This review highlights the current understanding of the complexity between HPV+ve and HPV-ve HNSCC TME and various tumor-stromal cross-talk modulating processes, including epithelial-mesenchymal transition (EMT), anoikis resistance, angiogenesis, immune surveillance, metastatic niche, therapeutic resistance, and development of an aggressive tumor phenotype. Furthermore, we summarize the recent developments and the rationale behind CIT strategies and their clinical applications in HPV+ve and HPV-ve HNSCC.

Cytokine-chemokine network driven metastasis in esophageal cancer; promising avenue for targeted therapy.

Esophageal cancer (EC) is a disease often marked by aggressive growth and poor prognosis. Lack of targeted therapies, resistance to chemoradiation therapy, and distant metastases among patients with advanced disease account for the high mortality rate. The tumor microenvironment (TME) contains several cell types, including fibroblasts, immune cells, adipocytes, stromal proteins, and growth factors, which play a significant role in supporting the growth and aggressive behavior of cancer cells. The complex and dynamic interactions of the secreted cytokines, chemokines, growth factors, and their receptors mediate chronic inflammation and immunosuppressive TME favoring tumor progression, metastasis, and decreased response to therapy. The molecular changes in the TME are used as biological markers for diagnosis, prognosis, and response to treatment in patients. This review highlighted the novel insights into the understanding and functional impact of deregulated cytokines and chemokines in imparting aggressive EC, stressing the nature and therapeutic consequences of the cytokine-chemokine network. We also discuss cytokine-chemokine oncogenic potential by contributing to the Epithelial-Mesenchymal Transition (EMT), angiogenesis, immunosuppression, metastatic niche, and therapeutic resistance development. In addition, it discusses the wide range of changes and intracellular signaling pathways that occur in the TME. Overall, this is a relatively unexplored field that could provide crucial insights into tumor immunology and encourage the effective application of modulatory cytokine-chemokine therapy to EC.

Takotsubo Syndrome: Finally Emerging From the Shadows?

It is now 30 years since Japanese investigators first described Takotsubo Syndrome (TTS) as a disorder occurring mainly in ageing women, ascribing it to the impact of multivessel coronary artery spasm. During the intervening period, it has become clear that TTS involves relatively transient vascular injury, followed by prolonged myocardial inflammatory and eventually fibrotic changes. Hence symptomatic recovery is generally slow, currently an under-recognised issue. It appears that TTS is induced by aberrant post-ß2-adrenoceptor signalling in the setting of "surge" release of catecholamines. Resultant activation of nitric oxide synthases and increased inflammatory vascular permeation lead to prolonged myocardial infiltration with macrophages and associated oedema formation. Initially, the diagnosis of TTS was made via exclusion of relevant coronary artery stenoses, plus the presence of regional left ventricular hypokinesis. However, detection of extensive myocardial oedema on cardiac MRI imaging offers a specific basis for diagnosis. No adequate methods are yet available for definitive diagnosis of TTS at hospital presentation. Other major challenges remaining in this area include understanding of the recently demonstrated association between TTS and antecedent cancer, the development of effective treatments to reduce risk of short-term (generally due to shock) and long-term mortality, and also to accelerate symptomatic recovery.

Non-invasive biomarkers for monitoring the immunotherapeutic response to cancer.

Immunotherapy is an efficient way to cure cancer by modulating the patient's immune response. However, the immunotherapy response is heterogeneous and varies between individual patients and cancer subtypes, reinforcing the need for early benefit predictors. Evaluating the infiltration of immune cells in the tumor and changes in cell-intrinsic tumor characteristics provide potential response markers to treatment. However, this approach requires invasive sampling and may not be suitable for real-time monitoring of treatment response. The recent emergence of quantitative imaging biomarkers provides promising opportunities. In vivo imaging technologies that interrogate T cell responses, metabolic activities, and immune microenvironment could offer a powerful tool to monitor the cancer response to immunotherapy. Advances in imaging techniques to identify tumors' immunological characteristics can help stratify patients who are more likely to respond to immunotherapy. This review discusses the metabolic events that occur during T cell activation and differentiation, anti-cancer immunotherapy-induced T cell responses, focusing on non-invasive imaging techniques to monitor T cell metabolism in the search for novel biomarkers of response to cancer immunotherapy.

Biventricular pacemaker therapy improves exercise capacity in patients with non-obstructive hypertrophic cardiomyopathy via augmented diastolic filling on exercise.

AIMS: Treatment options for patients with non-obstructive hypertrophic cardiomyopathy (HCM) are limited. We sought to determine whether biventricular (BiV) pacing improves exercise capacity in HCM patients, and whether this is via augmented diastolic filling. METHODS AND RESULTS: Thirty-one patients with symptomatic non-obstructive HCM were enrolled. Following device implantation, patients underwent detailed assessment of exercise diastolic filling using radionuclide ventriculography in BiV and sham pacing modes. Patients then entered an 8-month crossover study of BiV and sham pacing in random order, to assess the effect on exercise capacity [peak oxygen consumption (VO2 )]. Patients were grouped on pre-specified analysis according to whether left ventricular end-diastolic volume increased (+LVEDV) or was unchanged/decreased (-LVEDV) with exercise at baseline. Twenty-nine patients (20 male, mean age 55 years) completed the study. There were 14 +LVEDV patients and 15 -LVEDV patients. Baseline peak VO2 was lower in -LVEDV patients vs. +LVEDV patients (16.2 ± 0.9 vs. 19.9 ± 1.1 mL/kg/min, P = 0.04). BiV pacing significantly increased exercise ΔLVEDV (P = 0.004) and Δstroke volume (P = 0.008) in -LVEDV patients, but not in +LVEDV patients. Left ventricular ejection fraction and end-systolic elastance did not increase with BiV pacing in either group. This translated into significantly greater improvements in exercise capacity (peak VO2 + 1.4 mL/kg/min, P = 0.03) and quality of life scores (P = 0.02) in -LVEDV patients during the crossover study. There was no effect on left ventricular mechanical dyssynchrony in either group. CONCLUSION: Symptomatic patients with non-obstructive HCM may benefit from BiV pacing via augmentation of diastolic filling on exercise rather than contractile improvement. This may be due to relief of diastolic ventricular interaction. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov NCT00504647.

Claudin-1, A Double-Edged Sword in Cancer.

Claudins, a group of membrane proteins involved in the formation of tight junctions, are mainly found in endothelial or epithelial cells. These proteins have attracted much attention in recent years and have been implicated and studied in a multitude of diseases. Claudins not only regulate paracellular transepithelial/transendothelial transport but are also critical for cell growth and differentiation. Not only tissue-specific but the differential expression in malignant tumors is also the focus of claudin-related research. In addition to up- or down-regulation, claudin proteins also undergo delocalization, which plays a vital role in tumor invasion and aggressiveness. Claudin (CLDN)-1 is the most-studied claudin in cancers and to date, its role as either a tumor promoter or suppressor (or both) is not established. In some cancers, lower expression of CLDN-1 is shown to be associated with cancer progression and invasion, while in others, loss of CLDN-1 improves the patient survival. Another topic of discussion regarding the significance of CLDN-1 is its localization (nuclear or cytoplasmic vs perijunctional) in diseased states. This article reviews the evidence regarding CLDN-1 in cancers either as a tumor promoter or suppressor from the literature and we also review the literature regarding the pattern of CLDN-1 distribution in different cancers, focusing on whether this localization is associated with tumor aggressiveness. Furthermore, we utilized expression data from The Cancer Genome Atlas (TCGA) to investigate the association between CLDN-1 expression and overall survival (OS) in different cancer types. We also used TCGA data to compare CLDN-1 expression in normal and tumor tissues. Additionally, a pathway interaction analysis was performed to investigate the interaction of CLDN-1 with other proteins and as a future therapeutic target.

Long-lasting blood pressure lowering effects of nitrite are NO-independent and mediated by hydrogen peroxide, persulfides, and oxidation of protein kinase G1α redox signalling.

AIMS: Under hypoxic conditions, nitrite (NO2-) can be reduced to nitric oxide (NO) eliciting vasorelaxation. However, nitrite also exerts vasorelaxant effects of potential therapeutic relevance under normal physiological conditions via undetermined mechanisms. We, therefore, sought to investigate the mechanism(s) by which nitrite regulates the vascular system in normoxia and, specifically, whether the biological effects are a result of NO generation (as in hypoxia) or mediated via alternative mechanisms involving classical downstream targets of NO [e.g. effects on protein kinase G1α (PKG1α)]. METHODS AND RESULTS: Ex vivo myography revealed that, unlike in thoracic aorta (conduit vessels), the vasorelaxant effects of nitrite in mesenteric resistance vessels from wild-type (WT) mice were NO-independent. Oxidants such as H2O2 promote disulfide formation of PKG1α, resulting in NO- cyclic guanosine monophosphate (cGMP) independent kinase activation. To explore whether the microvascular effects of nitrite were associated with PKG1α oxidation, we used a Cys42Ser PKG1α knock-in (C42S PKG1α KI; 'redox-dead') mouse that cannot transduce oxidant signals. Resistance vessels from these C42S PKG1α KI mice were markedly less responsive to nitrite-induced vasodilation. Intraperitoneal (i.p.) bolus application of nitrite in conscious WT mice induced a rapid yet transient increase in plasma nitrite and cGMP concentrations followed by prolonged hypotensive effects, as assessed using in vivo telemetry. In the C42S PKG1α KI mice, the blood pressure lowering effects of nitrite were lower compared to WT. Increased H2O2 concentrations were detected in WT resistance vessel tissue challenged with nitrite. Consistent with this, increased cysteine and glutathione persulfide levels were detected in these vessels by mass spectrometry, matching the temporal profile of nitrite's effects on H2O2 and blood pressure. CONCLUSION: Under physiological conditions, nitrite induces a delayed and long-lasting blood pressure lowering effect, which is NO-independent and occurs via a new redox mechanism involving H2O2, persulfides, and PKG1α oxidation/activation. Targeting this novel pathway may provide new prospects for anti-hypertensive therapy.

Inorganic nitrate and nitrite supplementation fails to improve skeletal muscle mitochondrial efficiency in mice and humans.

BACKGROUND: Inorganic nitrate, abundant in leafy green vegetables and beetroot, is thought to have protective health benefits. Adherence to a Mediterranean diet reduces the incidence and severity of coronary artery disease, whereas supplementation with nitrate can improve submaximal exercise performance. Once ingested, oral commensal bacteria may reduce nitrate to nitrite, which may subsequently be reduced to nitric oxide during conditions of hypoxia and in the presence of "nitrite reductases" such as heme- and molybdenum-containing enzymes. OBJECTIVE: We aimed to explore the putative effects of inorganic nitrate and nitrite on mitochondrial function in skeletal muscle. METHODS: Mice were subjected to a nitrate/nitrite-depleted diet for 2 wk, then supplemented with sodium nitrate, sodium nitrite, or sodium chloride (1 g/L) in drinking water ad libitum for 7 d before killing. Skeletal muscle mitochondrial function and expression of uncoupling protein (UCP) 3, ADP/ATP carrier protein (AAC) 1 and AAC2, and pyruvate dehydrogenase (PDH) were assessed by respirometry and Western blotting. Studies were also undertaken in human skeletal muscle biopsies from a cohort of coronary artery bypass graft patients treated with either sodium nitrite (30-min infusion of 10 µmol/min) or vehicle [0.9% (wt:vol) saline] 24 h before surgery. RESULTS: Neither sodium nitrate nor sodium nitrite supplementation altered mitochondrial coupling efficiency in murine skeletal muscle, and expression of UCP3, AAC1, or AAC2, and PDH phosphorylation status did not differ between the nitrite and saline groups. Similar results were observed in human samples. CONCLUSIONS: Sodium nitrite failed to improve mitochondrial metabolic efficiency, rendering this mechanism implausible for the purported exercise benefits of dietary nitrate supplementation. This trial was registered at clinicaltrials.gov as NCT04001283.

Hypocapnia Alone Fails to Provoke Important Electrocardiogram Changes in Coronary Artery Diseased Patients.

BACKGROUND: There is still an urgent clinical need to develop non-invasive diagnostic tests for early ischemic heart disease because, once angina occurs, it is too late. Hypocapnia has long been known to cause coronary artery vasoconstriction. Some new cardiology tests are accompanied by the claim that they must have potential diagnostic value if hypocapnia enhances their cardiac effects in healthy subjects. But no previous study has tested whether hypocapnia produces bigger cardiac effects in patients with angina than in healthy subjects. METHODS: Severe hypocapnia (a PetCO2 level of 20 mmHg) lasting >15 min was mechanically induced by facemask, while conscious and unmedicated, in 18 healthy subjects and in 10 patients with angina and angiographically confirmed coronary artery disease, awaiting by-pass surgery. Each participant was their own control in normocapnia (where CO2 was added to the inspirate) and the order of normocapnia and hypocapnia was randomized. Twelve lead electrocardiograms (ECG) were recorded and automated measurements were made on all ECG waveforms averaged over >120 beats. 2D echocardiography was also performed on healthy subjects. RESULTS: In the 18 healthy subjects, we confirm that severe hypocapnia (a mean PetCO2 of 20 ± 0 mmHg, P < 0.0001) consistently increased the mean T wave amplitude in leads V1-V3, but by only 31% (P < 0.01), 15% (P < 0.001) and 11% (P < 0.05), respectively. Hypocapnia produced no other significant effects (p > 0.05) on their electro- or echocardiogram. All 10 angina patients tolerated the mechanical hyperventilation well, with minimal discomfort. Hypocpania caused a similar increase in V1 (by 39%, P < 0.05 vs. baseline, but P > 0.05 vs. healthy controls) and did not induce angina. Its effects were no greater in patients who did not take ß-blockers, or did not take organic nitrates, or had the worst Canadian Cardiovascular Society scores. CONCLUSION: Non-invasive mechanical hyperventilation while awake and unmedicated is safe and acceptable, even to patients with angina. Using it to produce severe and prolonged hypocapnia alone does produce significant ECG changes in angina patients. But its potential diagnostic value for identifying patients with coronary stenosis requires further evaluation.

Alterations in Cardiac Deformation, Timing of Contraction and Relaxation, and Early Myocardial Fibrosis Accompany the Apparent Recovery of Acute Stress-Induced (Takotsubo) Cardiomyopathy: An End to the Concept of Transience.

BACKGROUND: Takotsubo syndrome is an increasingly recognized cause of chest pain and occasionally of cardiogenic shock. Despite rapid improvement of the left ventricular (LV) ejection fraction, recent registry data raise concerns about long-term prognosis. The aim of this study was to test the hypothesis that restoration of normal ejection fraction after acute takotsubo syndrome is not equivalent to full functional recovery. METHODS: Fifty-two patients with takotsubo syndrome (according to the Mayo Clinic criteria plus cardiac magnetic resonance imaging to exclude myocardial infarction) and 44 healthy control subjects of the same age, gender, and cardiovascular comorbidity distribution were prospectively recruited. The focus of the investigation was on patients with takotsubo syndrome presenting with ST-segment elevation-type electrocardiographic findings or malignant arrhythmias and with LV apical ballooning variant, and a 4-month recovery endpoint was assessed. Patients underwent echocardiographic assessment of LV myocardial deformation (global longitudinal, radial, and circumferential strain; LV twist, torsion, and untwist; and time to peak twist and untwist) and assessment of LV myocardial structure by pre- and post-contrast-enhanced cardiac magnetic resonance by T1 mapping acutely and at 4-month follow-up. Control subjects underwent a single-time-point investigation. Data were analyzed using paired or unpaired tests, as appropriate for their distribution, and corrected for multiple comparisons. RESULTS: The patients' mean age was 66 years (range, 28-87 years), and 92% were women. All abnormal echocardiographic indices observed acutely in patients with takotsubo syndrome improved (but did not necessarily normalize) at follow-up. Significant mechanotemporal alterations characterizing both systole (global longitudinal strain and apical circumferential strain, P < .01 for both; LV twist, twist rate, and torsion, P < .0001 for all) and diastole (untwist rate and time to peak untwisting, P < .001 for both) persisted at 4-month follow-up compared with control subjects, despite normalization of LV ejection fraction and volumes. Although native T1 (which demonstrates edema) normalized at 4-months follow-up only in segments contracting normally during the acute phase (T1 = 1,180 ± 40.6 msec [normally contracting segments, P = .20 vs control value of 1,189 ± 16 msec] and T1 = 1,208 ± 60.3 msec [dysfunctional segments, P < .05 vs control]), the extracellular volume fraction (which demonstrates diffuse fibrosis) remained significantly abnormal in all LV segments (whether normally contracting [0.328 ± 0.043, P < .001] or ballooning during acute presentation [0.320 ± 0.044, P < .001], both vs control value of 0.273 ± 0.045). CONCLUSIONS: In patients with the most clinically severe spectrum of takotsubo cardiomyopathy, regional LV systolic and diastolic deformation abnormalities persist beyond the acute event, despite normalization of global LV ejection fraction and size. In addition, although myocardial edema partly subsides, a process of global microscopic fibrosis develops in its place, detected as early as 4 months.

Present and future pharmacotherapeutic agents in heart failure: an evolving paradigm.

Many conditions culminate in heart failure (HF), a multi-organ systemic syndrome with an intrinsically poor prognosis. Pharmacotherapeutic agents that correct neurohormonal dysregulation and haemodynamic instability have occupied the forefront of developments within the treatment of HF in the past. Indeed, multiple trials aimed to validate these agents in the 1980s and early 1990s, resulting in a large and robust evidence-base supporting their use clinically. An established treatment paradigm now exists for the treatment of HF with reduced ejection fraction (HFrEF), but there have been very few notable developments in recent years. HF remains a significant health concern with an increasing incidence as the population ages. We may indeed be entering the surgical era for HF treatment, but these therapies remain expensive and inaccessible to many. Newer pharmacotherapeutic agents are slowly emerging, many targeting alternative therapeutic pathways, but with mixed results. Metabolic modulation and manipulation of the nitrate/nitrite/nitric oxide pathway have shown promise and could provide the answers to fill the therapeutic gap between medical interventions and surgery, but further definitive trials are warranted. We review the significant evidence base behind the current medical treatments for HFrEF, the physiology of metabolic impairment in HF, and discuss two promising novel agents, perhexiline and nitrite.

Stereoselective handling of perhexiline: implications regarding accumulation within the human myocardium.

PURPOSE: Perhexiline is a prophylactic anti-ischaemic agent with weak calcium antagonist effect which has been increasingly utilised in the management of refractory angina. The metabolic clearance of perhexiline is modulated by CYP2D6 metaboliser status and stereoselectivity. The current study sought to (1) determine whether the acute accumulation of perhexiline in the myocardium is stereoselective and (2) investigate the relationship between duration of short-term therapy and the potential stereoselective effects of perhexiline within myocardium. METHOD: Patients (n = 129) from the active arm of a randomised controlled trial of preoperative perhexiline in cardiac surgery were treated with oral perhexiline for a median of 9 days. Correlates of atrial and ventricular concentrations of enantiomers were sought via univariate followed by multivariate analyses. RESULTS: Myocardial uptake of both (+) and (-) perhexiline was greater in ventricles than in atria, and there was more rapid clearance of (-) than (+) perhexiline. The main determinants of atrial uptake of both (+) and (-) perhexiline were the plasma concentrations [(+) perhexiline: ß = -0.256, p = 0.015; (-) perhexiline: ß = -0.347, p = 0.001] and patients' age [(+) perhexiline: ß = 0.300, p = 0.004; (-) perhexiline: ß = 0.288, p = 0.005]. Atrial uptake of (+) enantiomer also varied directly with duration of therapy (ß = 0.228, p = 0.025), while atrial uptake of (-) perhexiline varied inversely with simultaneous heart rate (ß = -0.240, p = 0.015). CONCLUSION: (1) Uptake of both perhexiline enantiomers into atrium is greater with advanced age and displays evidence of both saturability and minor stereoselectivity. (2) Atrial uptake of (-) perhexiline may selectively modulate heart rate reduction.

Improvement in cardiac energetics by perhexiline in heart failure due to dilated cardiomyopathy.

OBJECTIVES: The aim of this study was to determine whether short-term treatment with perhexiline improves cardiac energetics, left ventricular function, and symptoms of heart failure by altering cardiac substrate utilization. BACKGROUND: Perhexiline improves exercise capacity and left ventricular ejection fraction (LVEF) in patients with heart failure (HF). (31)P cardiac magnetic resonance spectroscopy can be used to quantify the myocardial phosphocreatine/adenosine triphosphate ratio. Because improvement of HF syndrome can improve cardiac energetics secondarily, we investigated the effects of short-term perhexiline therapy. METHODS: Patients with systolic HF of nonischemic etiology (n = 50, 62 ± 1.8 years of age, New York Heart Association functional class II to IV, LVEF: 27.0 ± 1.44%) were randomized to receive perhexiline 200 mg or placebo for 1 month in a double-blind fashion. Clinical assessment, echocardiography, and (31)P cardiac magnetic resonance spectroscopy were performed at baseline and after 1 month. A substudy of 22 patients also underwent cross-heart blood sampling at completion of the study to quantify metabolite utilization. RESULTS: Perhexiline therapy was associated with a 30% increase in the phosphocreatine/adenosine triphosphate ratio (from 1.16 ± 0.39 to 1.51 ± 0.51; p < 0.001) versus a 3% decrease with placebo (from 1.36 ± 0.31 to 1.34 ± 0.31; p = 0.37). Perhexiline therapy also led to an improvement in New York Heart Association functional class compared with placebo (p = 0.036). Short-term perhexiline therapy did not change LVEF. Cross-heart measures of cardiac substrate uptake and respiratory exchange ratio (which reflects the ratio of substrates used) did not differ between patients who received perhexiline versus placebo. CONCLUSIONS: Perhexiline improves cardiac energetics and symptom status with no evidence of altered cardiac substrate utilization. No change in LVEF is seen at this early stage. (Metabolic Manipulation in Chronic Heart Failure; NCT00841139).