Cardiac Metastatic Melanoma Causing Ventricular Arrhythmias Through Impaired Coronary Artery Vasodilation.

Melanoma is an aggressive malignant disease with a high rate of cardiac metastasis. There is a reported association between myocardial tumor invasion and ventricular arrhythmias. We present a case of cardiac metastatic melanoma causing ventricular arrhythmias through a novel mechanism of encasement of coronary arteries leading to reduced myocardial perfusion. (Level of Difficulty: Intermediate.).

Sustained monomorphic ventricular tachycardia as the presenting sign of Chagas' cardiomyopathy in a low prevalence setting, diagnosis and management challenges. A case report.

Approximately 300,000 people in the United States are estimated to have Chagas' disease, with cardiac manifestations including arrhythmias occurring in 20%-30% of patients. We report a patient diagnosed with Chagas' cardiomyopathy after presenting in ventricular tachycardia. This patient was asymptomatic before her presentation with recurrent episodes of ventricular tachycardia, which motivated us to screen her since she was an immigrant from an endemic Chagas region. This manuscript highlights some of the characteristic cardiac magnetic resonance imaging (MRI) and electrophysiology findings present in patients with Chagas' cardiomyopathy. We also detail the management of patients with Chagas' cardiomyopathy who have suffered from ventricular tachycardia.

Untemplated Resveratrol-Mediated Polydopamine Nanocapsule Formation.

Nanocapsules can be designed for applications including drug delivery, catalysis, and biological imaging. The mussel-inspired material polydopamine is a promising shell layer for nanocapsules because of its free radical scavenging capacity, ability to react with a broad range of functional molecules, lack of toxicity, and biodegradability. Previous reports of polydopamine nanocapsule formation have relied on a templating approach. Herein, we report a template-free approach to polydopamine nanocapsule formation in the presence of resveratrol, a naturally occurring anti-inflammatory and antioxidant compound found in red wine and grapes. Synthesis of nanocapsules occurs spontaneously in an ethanolic resveratrol/dopamine·HCl solution at pH 8.5. UV-vis absorbance spectroscopy and X-ray photoelectron spectroscopy indicate that resveratrol is incorporated into the nanocapsules. We also observed the formation of a soluble fluorescent dopamine-resveratrol adduct during synthesis, which was identified by high-performance liquid chromatography, UV-vis spectroscopy, and electrospray ionization mass spectrometry. Using transmission electron microscopy and dynamic light scattering, we studied the influence of solvent composition, dopamine concentration, and resveratrol/dopamine ratio on the nanocapsule diameter and shell thickness. The resulting nanocapsules have excellent free radical scavenging activity as measured by a 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. Our work provides a convenient pathway by which resveratrol, and possibly other hydrophobic bioactive compounds, may be encapsulated within polydopamine nanocapsules.

Size Control and Fluorescence Labeling of Polydopamine Melanin-Mimetic Nanoparticles for Intracellular Imaging.

As synthetic analogs of the natural pigment melanin, polydopamine nanoparticles (NPs) are under active investigation as non-toxic anticancer photothermal agents and as free radical scavenging therapeutics. By analogy to the widely adopted polydopamine coatings, polydopamine NPs offer the potential for facile aqueous synthesis and incorporation of (bio)functional groups under mild temperature and pH conditions. However, clear procedures for the convenient and reproducible control of critical NP properties such as particle diameter, surface charge, and loading with functional molecules have yet to be established. In this work, we have synthesized polydopamine-based melanin-mimetic nanoparticles (MMNPs) with finely controlled diameters spanning ≈25 to 120 nm and report on the pH-dependence of zeta potential, methodologies for PEGylation, and the incorporation of fluorescent organic molecules. A comprehensive suite of complementary techniques, including dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), X-ray photoelectron spectroscopy (XPS), zeta-potential, ultraviolet-visible (UV-Vis) absorption and fluorescence spectroscopy, and confocal microscopy, was used to characterize the MMNPs and their properties. Our PEGylated MMNPs are highly stable in both phosphate-buffered saline (PBS) and in cell culture media and exhibit no cytotoxicity up to at least 100 µg mL-1 concentrations. We also show that a post-functionalization methodology for fluorophore loading is especially suitable for producing MMNPs with stable fluorescence and significantly narrower emission profiles than previous reports, suggesting they will be useful for multimodal cell imaging. Our results pave the way towards biomedical imaging and possibly drug delivery applications, as well as fundamental studies of MMNP size and surface chemistry dependent cellular interactions.