Matthew J. Provenzano

The ErbB inhibitors trastuzumab and erlotinib inhibit growth of vestibular schwannoma xenografts in nude mice: a preliminary study.

Objective: To analyze the ability of ErbB inhibitors to reduce the growth of vestibular schwannoma (VS) xenografts. Methods: Vestibular schwannoma xenografts were established in the interscapular fat pad in nude mice for 4 weeks. Initially, a small cohort of animals was treated with the ErbB2 inhibitor trastuzumab or saline for 2 weeks. Animals also received bromodeoxyuridine injections to label proliferating cells. In a longer-term experiment, animals were randomized to receive trastuzumab, erlotinib (an ErbB kinase inhibitor), or placebo for 12 weeks. Tumor growth was monitored by magnetic resonance imaging during the treatment period. Cell death was analyzed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling of fragmented DNA. Results: Tumors can be distinguished with T2-weighted magnetic resonance imaging sequences. Trastuzumab significantly reduced the proliferation of VS cells compared with control (p < 0.01) as analyzed by bromodeoxyuridine uptake. Control tumors demonstrated slight growth during the 12-week treatment period. Both trastuzumab and erlotinib significantly reduced the growth of VS xenografts (p < 0.05). Erlotinib, but not trastuzumab, resulted in a significant increase in the percentage of terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling of fragmented DNA-positive VS cells (p < 0.01). Conclusion: In this preliminary study, the ErbB inhibitors trastuzumab and erlotinib decreased growth of VS xenografts in nude mice, raising the possibility of using ErbB inhibitors in the management of patients with schwannomas, particularly those with neurofibromatosis Type 2.

p75NTR expression and nuclear localization of p75NTR intracellular domain in spiral ganglion Schwann cells following deafness correlate with cell proliferation

Spiral ganglion Schwann cells (SGSCs) myelinate spiral ganglion neurons (SGNs) and represent a potential source of neurotrophic support for SGNs. Deafening due to loss of hair cells results in gradual degeneration and death of SGNs. Successful efforts to maintain or regenerate a functional auditory nerve may depend on a healthy population of SGSCs, yet the responses of SGSCs to neural injury remain largely unknown. Here we investigate the role of p75(NTR) in SGSC responses to gradual denervation. Following deafening, SGSCs in the osseous spiral lamina (OSL) and, subsequently, in Rosenthals canal (RC) expressed elevated p75(NTR) compared to hearing controls. p75(NTR)-positive cells co-labeled with S100 and RIP antibodies (Schwann cell markers), but not with anti-neurofilament. The pattern of p75(NTR) expression mirrored the pattern of neural degeneration, beginning in the OSL of the cochlea base and later extending into the apex. SGSCs expressed sortilin, a p75(NTR) co-receptor for pro-neurotrophins. Both pro-nerve growth factor (pro-NGF) and pro-brain derived neurotrophic factor (proBDNF) induced apoptosis in cultured SGSCs. Deafened animals exhibited significantly higher levels of SGSC proliferation (as measured by BrdU uptake) compared to hearing animals while total Schwann cell density remained stable, suggesting a tight regulation of SGSC proliferation and cell death. SGSCs undergoing cell division lose p75(NTR) expression from the cell surface and demonstrate nuclear localization of the intracellular domain (ICD), raising the possibility that p75(NTR) cleavage and ICD nuclear localization regulate SGSC proliferation. These results suggest that p75(NTR) contributes to SGSC responses to deafening and neural degeneration.

p75NTR and Sortilin Increase After Facial Nerve Injury

Objectives: After axotomy, Schwann cells (SCs), required for successful nerve regeneration, undergo a number of cellular changes including dedifferentiation, proliferation, expression of molecules that support axon growth, and apoptosis. This study investigated the role of p75NTR, sortilin, and proneurotrophins in SC survival after facial nerve (FN) axotomy.

A role for epigenetics in hearing: Establishment and maintenance of auditory specific gene expression patterns.

Epigenetics is a large and diverse field encompassing a number of different mechanisms essential to development, DNA stability and gene expression. DNA methylation and histone modifications work individually and in conjunction with each other leading to phenotypic changes. An overwhelming amount of evidence exists demonstrating the essential nature of epigenetics to human biology and pathology. This field has spawned a vast array of knowledge, techniques and pharmaceuticals designed to investigate and manipulate epigenetic phenomena. Despite its centricity to molecular biology, little work has been conducted examining how epigenetics affects hearing. In this review, we discuss both the basic tenets of epigenetics and highlight the most recent advances in this field. We discuss its importance to human development, genomic stability, gene expression, epigenetic modifying agents as well as briefly introduce the expansive field of cancer epigenetics. We then examine the evidence of a role for epigenetics in hearing related processes and hearing loss. The article concludes with a discussion of areas of epigenetic research that could be applied to hearing research.

Human chondrosarcoma cells acquire an epithelial-like gene expression pattern via an epigenetic switch: Evidence for mesenchymal-epithelial transition during sarcomagenesis

Chondrocytes are mesenchymally derived cells that reportedly acquire some epithelial characteristics; however, whether this is a progression through a mesenchymal to epithelial transition (MET) during chondrosarcoma development is still a matter of investigation. We observed that chondrosarcoma cells acquired the expression of four epithelial markers, E-cadherin,desmocollin 3, maspin, and 14-3-3σ, all of which are governed epigenetically through cytosine methylation. Indeed, loss of cytosine methylation was tightly associated with acquired expression of both maspin and 14-3-3σ in chondrosarcomas. In contrast, chondrocyte cells were negative for maspin and 14-3-3σ and displayed nearly complete DNA methylation. Robust activation of these genes was also observed in chondrocyte cells following 5-aza-dC treatment. We also examined the transcription factor snail which has been reported to be an important mediator of epithelial to mesenchymal transitions (EMTs). In chondrosarcoma cells snail is downregulated suggesting a role for loss of snail expression in lineage maintenance. Taken together, these results document an epigenetic switch associated with an MET-like phenomenon that accompanies chondrosarcoma progression.

Regulation of 14-3-3σ expression in human thyroid carcinoma is epigenetically regulated by aberrant cytosine methylation

Increased 14-3-3sigma expression has been observed by immunohistochemistry in papillary and anaplastic tumors, but not follicular thyroid cancers. 14-3-3sigma mRNA expression and methylation status was examined in tumor cell lines and primary thyroid tissues using real-time RT-PCR, bisulfite sequencing and methylation-specific PCR. Most of the 27 CpGs in the genes CpG island were methylated in normal thyroid, TPC-1, NPA, FTC-238 and 2-7, which did not express 14-3-3sigma. In contrast, they were unmethylated in KAK-1 and anaplastic lines KAT4 and DRO-90. 14-3-3sigma expression was not increased in thyroid carcinomas, the majority of which had a methylated CpG island. In addition, 5-aza-dC treatment increased 14-3-3sigma expression in the FTC-238 and NPA cell lines, which had low baseline expression. We conclude 14-3-3sigma expression in thyroid carcinomas is regulated by CpG island hypermethylation.

Use of the King LT for emergency airway management.

OBJECTIVE To discuss the role of the King LT reusable supraglottic airway in emergency airway management. DESIGN Retrospective case series review. SETTING Tertiary academic medical facility. PATIENTS We studied patients who presented to the emergency trauma center having undergone intubation at an outside facility or at the scene of the incident. The otolaryngology service was consulted for definitive management of the airway. MAIN OUTCOME MEASURE Airway evaluation and management once the King LT has been placed. RESULTS Six patients with known prehospitalization use of the King LT presented to the emergency trauma center and subsequently required emergency tracheostomy for establishment of a secure airway. Fiberoptic and/or direct laryngoscopic evaluation performed with the tube in place failed to reveal whether safe oral endotracheal intubation could be performed because of visualization problems. Examination after tracheostomy and removal of the King LT revealed that in 2 patients, orotracheal intubation would have been difficult or impossible, whereas another 4 patients could have been intubated. One patient had prehospitalization placement of a King LT, which resulted in subcutaneous emphysema because of placement within the mediastinum. The patient was able to be successfully intubated and did not require tracheostomy. CONCLUSIONS The King LT offers benefits in emergency situations, but evaluation of the airway is challenging and often necessitates tracheostomy for establishment of a safe and secure airway. Even if tracheostomy is not required, serious complications may occur.

Pediatric endoscopic airway management with posterior cricoid rib grafting.

To confirm and extend reported successful treatment of posterior glottic stenosis in pediatric patients using endoscopic laser division of the posterior cricoid plate with augmentation using costal cartilage.

A Novel Low Cost Task Trainer for Tonsillectomy Simulation

Objective: 1) Develop a novel low cost task trainer which appropriately simulates the basic steps involved in a tonsillectomy procedure for the novice trainee. 2) Assess this task trainer for feasibility, face validity, usability, and content validity using a group of expert observers. Method: The task trainer was developed to reproduce all steps of the tonsillectomy procedure using pieces of steak with adherent connective tissue to simulate the tonsil for electrocautery dissection. Pediatric otolaryngology attendings and fellows were surveyed using a 5-point Likert scale to assess ease of use, realism, and perceived utility. Results: The model consists of a Styrofoam head with cut-out oropharynx and steak pieces suspended by metal clips and wired to an electrocautery unit. Surgeons use a headlight, grasp the muscle, and electro-dissect it away from the fat. Cost of the model was twenty US dollars. Ten attending pediatric otolaryngologists and 4 pediatric otolaryngology fellows completed simulated tonsillectomies and surveys. Participants rated a median realism score of 4 out of 5 (very realistic) and ease of use a median 5 out of 5 (simple and intuitive). All participants agreed residents would be better prepared for real tonsillectomies after using the model. Conclusion: Production and use of a tonsillectomy task trainer is a feasible and inexpensive endeavor for training programs and may provide appropriate usability and fidelity in simulating tonsillectomy for trainees. Face and content validity were confirmed by expert observers. Further study will assess validity and effectiveness for teaching and assessment.

Cellular Iodine Transport: Body Distribution of the Human Sodium Iodide Symporter

This chapter examines the distribution of the symporter throughout the body. Special attention is paid to its biological significance, structure, and function. Each organ important to the iodine handling process is examined for evidence of expression of the symporter. The symporter is a large complex protein that is dependent on proper protein folding, posttranslational modifications, protein trafficking, cellular polarity, and cellular organization for its function. The symporter transports an iodide ion into the cell through an active process using sodium ions as cotransport molecules. The symporter is expressed in numerous organs of the body including the thyroid, stomach, breast, placenta, salivary glands and eye. Experiments examining mRNA levels, protein expression, and iodine uptake have demonstrated its presence in a host of organs and tissues. Much is already known of NIS function and regulation in organs such as the thyroid and breast. However, NIS expression in many parts of the body remains to be completely understood. The mechanisms controlling expression of the symporter are often tissue-dependent and rely on a number of different proteins and hormones. Disease states such as cancer can change the expression of the symporter.