Most applications of nanotechnology in cancer have focused on systemic delivery of cytotoxic drugs. Systemic delivery relies on accumulation of nanoparticles in a target tissue through enhanced permeability of leaky vasculature and retention effect of poor lymphatic drainage to increase the therapeutic index. Systemic delivery is limited, however, by toxicity and difficulty crossing natural obstructions, like the blood spine barrier. Magnetic drug targeting (MDT) is a new technique to reach tumors of the central nervous system. Here, we describe a novel therapeutic approach for high-grade intramedullary spinal cord tumors using magnetic nanoparticles (MNP). Using biocompatible compounds to form a superparamagnetic carrier and magnetism as a physical stimulus, MNP-conjugated with doxorubicin were successfully localized to a xenografted tumor in a rat model. This study demonstrates proof-of-concept that MDT may provide a novel technique for effective, concentrated delivery of chemotherapeutic agents to intramedullary spinal cord tumors without the toxicity of systemic administration.

Idiopathic SEL in the pediatric population is a rare entity. This is the first case of epidural lipomatosis isolated to the cervical region in an adult or child patient. In refractory, symptomatic cases of idiopathic SEL, surgical decompression is often required.

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Hereditary deafness is often a neurosensory disorder and affects the quality of life of humans. Only three X‐linked genes (POU class 3 homeobox 4 (POU3F4), phosphoribosyl pyrophosphate synthetase 1 (PRPS1), and small muscle protein X‐linked (SMPX)) are known to be involved in nonsyndromic hearing loss. Four PRPS1 missense mutations have been found to associate with X‐linked nonsyndromic sensorineural deafness (DFNX1/DFN2) in humans. However, a causative relationship between PRPS1 mutations and hearing loss in humans has not been well studied in any animal model. Phosphoribosyl pyrophosphate synthetase 1 (PRS‐I) is highly conserved in vertebrate taxa. In this study, we used the zebrafish as a model to investigate the auditory role of zebrafish orthologs (prps1a and prps1b) of the human PRPS1 gene with whole mount in situ hybridization, reverse transcription polymerase chain reaction, phenotypic screening, confocal imaging, and electrophysiological methods. We found that both prps1a and prps1b genes were expressed in the inner ear of zebrafish. Splice‐blocking antisense morpholino oligonucleotides (MO1 and MO2) caused exon‐2 skip and intron‐2 retention of prps1a and exon‐2 skip and intron‐1 retention of prps1b to knock down functions of the genes, respectively. MO1 and MO2 morphants had smaller otic vesicles and otoliths, fewer inner ear hair cells, and lower microphonic response amplitude and sensitivity than control zebrafish. Therefore, knockdown of either prps1a or prps1b resulted in significant sensorineural hearing loss in zebrafish. We conclude that the prps1 genes are essential for hearing in zebrafish, which has the potential to help us understand the biology of human deafness DFNX1/DFN2. Anat Rec, 303:544–555, 2020. © 2019 American Association for Anatomy

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