Mitochondrial Ca Uniporter-Dependent Energetic Dysfunction Drives Hypertrophy in Heart Failure.

The role of the mitochondrial calcium uniporter (MCU) in energy dysfunction and hypertrophy in heart failure (HF) remains unknown. In angiotensin II (ANGII)-induced hypertrophic cardiac cells we have shown that hypertrophic cells overexpress MCU and present bioenergetic dysfunction. However, by silencing MCU, cell hypertrophy and mitochondrial dysfunction are prevented by blocking mitochondrial calcium overload, increase mitochondrial reactive oxygen species, and activation of nuclear factor kappa B-dependent hypertrophic and proinflammatory signaling.

A novel method for determining murine skeletal muscle fiber type using autofluorescence lifetimes.

This work describes a simple way to identify fiber types in living muscles by fluorescence lifetime imaging microscopy (FLIM). We quantified the mean values of lifetimes τ1 and τ2 derived from a two-exponential fit in freshly dissected mouse flexor digitorum brevis (FDB) and soleus muscles. While τ1 values changed following a bimodal behavior between muscles, the distribution of τ2 is shifted to higher values in FDB.

Mitochondrial calcium uniporter complex activation protects against calcium alternans in atrial myocytes.

Cardiac alternans, defined as beat-to-beat alternations in action potential duration, cytosolic Ca transient (CaT) amplitude, and cardiac contraction is associated with atrial fibrillation (AF) and sudden cardiac death. At the cellular level, cardiac alternans is linked to abnormal intracellular calcium handling during excitation-contraction coupling. We investigated how pharmacological activation or inhibition of cytosolic Ca sequestration via mitochondrial Ca uptake and mitochondrial Ca retention affects the occurrence of pacing-induced CaT alternans in isolated rabbit atrial myocytes.

Amorphous SiO2 nanoparticles promote cardiac dysfunction via the opening of the mitochondrial permeability transition pore in rat heart and human cardiomyocytes.

Background: Silica nanoparticles (nanoSiO) are promising systems that can deliver biologically active compounds to tissues such as the heart in a controllable manner. However, cardiac toxicity induced by nanoSiO has been recently related to abnormal calcium handling and energetic failure in cardiomyocytes. Moreover, the precise mechanisms underlying this energetic debacle remain unclear.

Changes in the Stoichiometry of Uniplex Decrease Mitochondrial Calcium Overload and Contribute to Tolerance of Cardiac Ischemia/Reperfusion Injury in Hypothyroidism.

Thyroid hormone status in hypothyroidism (HT) downregulates key elements in Ca handling within the heart, reducing contractility, impairing the basal energetic balance, and increasing the risk of cardiovascular disease. Mitochondrial Ca transport is reduced in HT, and tolerance to reperfusion damage has been documented, but the precise mechanism is not well understood. Therefore, we aimed to determine the stoichiometry and activity of the mitochondrial Ca uniporter or uniplex in an HT model and the relevance to the opening of the mitochondrial permeability transition pores (mPTP) during ischemia/reperfusion (I/R) injury.

Nanoencapsulated Quercetin Improves Cardioprotection during Hypoxia-Reoxygenation Injury through Preservation of Mitochondrial Function.

The effective delivery of antioxidants to the cells is hindered by their high metabolization rate. In this work, quercetin was encapsulated in poly(lactic-co-glycolic) acid (PLGA) nanoparticles. They were characterized in terms of its physicochemical properties (particle size distribution, -potential, encapsulation efficiency, quercetin release and biological interactions with cardiac cells regarding nanoparticle association, and internalization and protective capability against relevant challenges).

Ex Vivo Cardiotoxicity of Antineoplastic Casiopeinas Is Mediated through Energetic Dysfunction and Triggered Mitochondrial-Dependent Apoptosis.

Casiopeinas are a group of copper-based antineoplastic molecules designed as a less toxic and more therapeutic alternative to cisplatin or Doxorubicin; however, there is scarce evidence about their toxic effects on the whole heart and cardiomyocytes. Given this, rat hearts were perfused with Casiopeinas or Doxorubicin and the effects on mechanical performance, energetics, and mitochondrial function were measured. As well, the effects of Casiopeinas-triggered cell death were explored in isolated cardiomyocytes.

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

Metabolic syndrome (MS) increases cardiovascular risk and is associated with cardiac dysfunction and arrhythmias, although the precise mechanisms are still under study. Chronic inflammation in MS has emerged as a possible cause of adverse cardiac events. Male Wistar rats fed with 30% sucrose in drinking water and standard chow for 25-27 weeks were compared to a control group.

Enhancing internalization of silica particles in myocardial cells through surface modification.

Surface modification in nanostructured mesoporous silica particles (MSNs) can significantly increase the uptake in myocardial cells. Herein, MSNs particles were synthesized and chemically functionalized to further assess their biocompatibility in rat myocardial cell line H9c2. The surface modification resulted in particles with an enhanced cellular internallization (3-fold increase) with respect to pristine particles.

Small Interfering RNA Targeting Mitochondrial Calcium Uniporter Improves Cardiomyocyte Cell Viability in Hypoxia/Reoxygenation Injury by Reducing Calcium Overload.

Intracellular Ca mishandling is an underlying mechanism in hypoxia/reoxygenation (H/R) injury that results in mitochondrial dysfunction and cardiomyocytes death. These events are mediated by mitochondrial Ca (Ca) overload that is facilitated by the mitochondrial calcium uniporter (MCU) channel. Along this line, we evaluated the effect of siRNA-targeting MCU in cardiomyocytes subjected to H/R injury.

Silica nanoparticles induce cardiotoxicity interfering with energetic status and Ca handling in adult rat cardiomyocytes.

Recent evidence has shown that nanoparticles that have been used to improve or create new functional properties for common products may pose potential risks to human health. Silicon dioxide (SiO) has emerged as a promising therapy vector for the heart. However, its potential toxicity and mechanisms of damage remain poorly understood.

Antineoplastic copper coordinated complexes (Casiopeinas) uncouple oxidative phosphorylation and induce mitochondrial permeability transition in cardiac mitochondria and cardiomyocytes.

Copper-based drugs, Casiopeinas (Cas), exhibit antiproliferative and antineoplastic activities in vitro and in vivo, respectively. Unfortunately, the clinical use of these novel chemotherapeutics could be limited by the development of dose-dependent cardiotoxicity. In addition, the molecular mechanisms underlying Cas cardiotoxicity and anticancer activity are not completely understood.

The receptor-binding domain of influenza virus hemagglutinin produced in Escherichia coli folds into its native, immunogenic structure.

The hemagglutinin (HA) surface glycoprotein promotes influenza virus entry and is the key protective antigen in natural immunity and vaccines. The HA protein is a trimeric envelope glycoprotein consisting of a globular receptor-binding domain (HA-RBD) that is inserted into a membrane fusion-mediating stalk domain. Similar to other class I viral fusion proteins, the fusogenic stalk domain spontaneously refolds into its postfusion conformation when expressed in isolation, consistent with this domain being trapped in a metastable conformation.

An influenza A/H1N1/2009 hemagglutinin vaccine produced in Escherichia coli.

Background: The A/H1N1/2009 influenza pandemic made evident the need for faster and higher-yield methods for the production of influenza vaccines. Platforms based on virus culture in mammalian or insect cells are currently under investigation. Alternatively, expression of fragments of the hemagglutinin (HA) protein in prokaryotic systems can potentially be the most efficacious strategy for the manufacture of large quantities of influenza vaccine in a short period of time.