Emergency department care of patients with Duchenne muscular dystrophy.

Patients with Duchenne muscular dystrophy are living longer and are increasingly seen in Emergency Departments. Though the most common cause of death remains progressive respiratory failure, increased life expectancies have unmasked the significance of progressive myocardial dysfunction, now associated with nearly 40% of mortalities in the DMD population. Cardiac complications such as arrhythmias and cardiomyopathy are becoming ever more widely recognized. Emergency physicians may encounter DMD patients with untreated, undiagnosed or worsening of known heart disease. This review will initially familiarize the emergency physician with the pathophysiology and lifetime trajectory of care for these patients before describing specific emergency department evaluation and treatment.

Corneal Penetrating Elastin-Like Polypeptide Carriers.

PURPOSE: Elastin-like polypeptide (ELP) is a bioengineered protein widely applied as a drug carrier due to its biocompatibility and amenability to modification with cell-penetrating peptides (CPPs) and therapeutic agents. The purpose of this study was to determine whether topically applied ELP or CPP-fused ELPs penetrate the corneal barrier. METHODS: In vitro binding and cytotoxicity to human corneal epithelial (HCE) cells were determined for ELP or CPP-ELPs. Corneal binding, clearance, and penetration were assessed in a rabbit model following topical application of the fluorescently labeled proteins by quantitative fluorescence imaging and histology. RESULTS: ELP bound to HCE cells in vitro, and binding/uptake was enhanced 2- to 3-fold by the addition of CPPs. When applied topically to rabbit eyes, ELP accumulated in the cornea at levels 7.4-fold higher than did an equivalent dose of immunoglobulin G. Both ELP and a CPP-ELP penetrated the corneal epithelium and were detectable in the stroma. Addition of CPPs to ELP, however, did not significantly enhance corneal uptake or penetration in vivo relative to ELP alone. The polypeptides cleared from the cornea over a period of 20-30 min after application, after which cornea levels reached a steady state of 15-30 µg/mL for up to 3 h. CONCLUSIONS: The ELP drug carrier can penetrate the corneal epithelium and accumulate in the stroma. Given its amenability for fusion to multiple types of therapeutic agents, ELP has the potential to serve as a drug carrier for topical ocular applications.

Growth factor purification and delivery systems (PADS) for therapeutic angiogenesis.

BACKGROUND: Therapeutic angiogenesis with vascular endothelial growth factor (VEGF), delivered either via recombinant protein infusion or via gene therapy, has shown promise in preclinical models of various diseases including myocardial infarction, renovascular disease, preeclampsia, and neurodegenerative disorders. However, dosing, duration of expression, and tissue specificity are challenges to VEGF gene therapy, and recombinant VEGF delivery suffers from extremely rapid plasma clearance, necessitating continuous infusion and/or direct injection at the site of interest. METHODS: Here we describe a novel growth factor purification and delivery system (PADS) generated by fusion of VEGF121 to a protein polymer based on Elastin-like Polypeptide (ELP). ELP is a thermally responsive biopolymer derived from a five amino acid repeat sequence found in human tropoelastin. VEGFPADS were constructed by fusion of the ELP coding sequence in-frame with the VEGF121 coding sequence connected by a flexible di-glycine linker. In vitro activity of VEGFPADS was determined using cell proliferation, tube formation, and migration assays with vascular endothelial cells. Pharmacokinetics and biodistribution of VEGFPADS in vivo were compared to free VEGF in mice using quantitative fluorescence techniques. RESULTS: ELP fusion allowed for recombinant expression and simple, non-chromatographic purification of the ELP-VEGF121 chimera in yields as high as 90 mg/L of culture and at very high purity. ELP fusion had no effect on the VEGF activity, as the VEGFPADS were equally potent as free VEGF121 in stimulating HUVEC proliferation, tube formation, and migration. Additionally, the VEGFPADS had a molecular weight five-fold larger than free VEGF121, which lead to slower plasma clearance and an altered biodistribution after systemic delivery in vivo. CONCLUSION: PADS represent a new method of both purification and in vivo stabilization of recombinant growth factors. The use of this system could permit recombinant growth factors to become viable options for therapeutic angiogenesis in a number of disease models.

A polypeptide drug carrier for maternal delivery and prevention of fetal exposure.

BACKGROUND: Pregnant females are largely overlooked in drug development due to concerns for fetal health. Additionally, pregnancy is often an exclusion criterion in clinical trials, so the safety of many drugs during pregnancy is unknown. PURPOSE: The goal of this study was to evaluate Elastin-like Polypeptide (ELP), a synthetic protein derived from human elastin, for maternally sequestered drug delivery. ELP is a versatile drug carrier with a long plasma half-life, low immunogenicity, and the ability to be fused to nearly any small molecule or protein-based therapeutic. METHODS: We determined the pharmacokinetics, biodistribution, and fetal exposure to the ELP drug carrier using quantitative fluorescence techniques in a rat pregnancy model. RESULTS: After either bolus IV administration or continuous infusion over five days, ELPs accumulated strongly in the kidneys, liver, and placenta, but importantly, little to no ELPs were detectable in the fetus. Within the placenta, ELPs were localized to the chorionic plate and broadly distributed within the labyrinth, but were excluded from the fetal portion of the chorionic villi. CONCLUSION: These data indicate that ELP does not cross the placenta, and they suggest that this adaptable drug delivery system is a promising platform for prevention of fetal drug exposure.