Duration of Eligibility Prior to Cochlear Implantation: Have We Made Any Progress?

OBJECTIVE: The objective is to determine if eligibility (as defined as the duration of severe to profound hearing loss before cochlear implantation [CI]) has changed over the 30 years since Food and Drug Administration approval. DATA SOURCES: English-language, peer-reviewed articles, theses, and trial data available through PubMed and Cochrane Library databases up until and including May 31, 2016. STUDY SELECTION: One thousand six unique articles were identified. Prospective studies that reported duration of severe/profound hearing loss before CI in adult patients were included. Retrospective studies, reviews, meta-analyses, articles reporting pediatric or mixed data, hybrid/electroacoustic CI, and articles from centers outside the United States were excluded. Seventy-one studies met inclusion criteria and were included for analysis. DATA EXTRACTION: Contributing authors independently reviewed included studies for data validity and applicability. DATA SYNTHESIS: Metaregression was used to assess the relationship between the year of publication and duration of hearing loss. To account for a possible age effect, a second model was estimated including mean age at the time of study as a covariate. CONCLUSION: A positive association between study year and the duration of hearing loss before implantation was found showing a 0.28-year increase in the duration of hearing loss for every increasing study year. Contrary to conventional assumption, duration of eligibility for CI appears to be increasing. Though the reasons for this are not clear, current strategies to increase both awareness and access to CI seem to be falling short.

Fabrication and in vitro characterization of gadolinium-based nanoclusters for simultaneous drug delivery and radiation enhancement.

We report the synthesis of a gadolinium hydroxide (Gd(OH)3) nanorod based doxorubicin (Dox) delivery system that can enhance both magnetic resonance imaging contrast and radiation sensitivity. A simple and cost effective wet-chemical method was utilized in the presence of manganese (Mn) ions and Dox to produce the Gd(OH)3:Mn·Dox nanocluster structure. The Gd(OH)3:Mn·Dox nanocluster was composed of Mn-doped Gd(OH)3 nanorods arranged in parallel with Dox as a linker molecule between the adjacent nanorods. No other studies have utilized Dox as both the linker and therapeutic molecule in a nanostructure to date. The Gd(OH)3 nanorod is reported to have no significant cellular or in vivo toxicity, which makes it an ideal base material for this biomedical application. The Gd(OH)3:Mn·Dox nanocluster exhibited paramagnetic behavior and was stable in a colloidal solution. The nanocluster also enabled high Dox loading capacity and specifically released Dox in a sustained and pH-dependent manner. The positively charged Gd(OH)3:Mn·Dox nanoclusters were readily internalized into MDA-MB-231 breast cancer cells via endocytosis, which resulted in intracellular release of Dox. The released Dox in cells was effective in conferring cytotoxicity and inhibiting proliferation of cancer cells. Furthermore, a synergistic anticancer effect could be observed with radiation treatment. Overall, the Gd(OH)3:Mn·Dox nanocluster drug delivery system described herein may have potential utility in clinics as a multifunctional theranostic nanoparticle with combined benefits in both diagnosis and therapy in the management of cancer.

Layered gadolinium-based nanoparticle as a novel delivery platform for microRNA therapeutics.

Specific expression patterns of microRNA (miRNA) molecules have been linked to cancer initiation, progression, and metastasis. The accumulating evidence for the role of oncogenic or tumor-suppressing miRNAs identified the need for nano-scaled platform that can help deliver nucleotides to modulate miRNAs. Here we report the synthesis of novel layered gadolinium hydroxychloride (LGdH) nanoparticles, a member of the layered double hydroxide (LDH) family, with physiochemical properties suitable for cell uptake and tracing via magnetic resonance (MR) imaging. As a proof of concept, we demonstrate the inhibition of mature miRNA-10b in metastatic breast cancer cell line using LGdH nanoparticle as a delivery platform. Through characterization analysis, we show that nanoparticles are easily and stably loaded with anti-miRNA oligonucleotides (AMO) and efficiently penetrate cell membranes. We demonstrate that AMOs delivered by LGdH nanoparticles remain functional by inducing changes in the expression of its downstream effector and by curbing the invasive properties. Furthermore, we demonstrate the traceability of LGdH nanoparticles via T1 weighted MR imaging. LGdH nanoparticles, which are biocompatible with cells in vitro, provide a promising multifunctional platform for microRNA therapeutics through their diagnostic, imaging, and therapeutic potentials.