Faculty Bibliography

Although the auditory system has limited information processing resources, the acoustic environment is infinitely variable. To properly encode the natural environment, the developing central auditory system becomes somewhat specialized through experience-dependent adaptive mechanisms that operate during a sensitive time window. Recent studies have demonstrated that cellular and synaptic plasticity occurs throughout the central auditory pathway. Acoustic-rearing experiments can lead to an over-representation of the exposed sound frequency, and this is associated with specific changes in frequency discrimination. These forms of cellular plasticity are manifest in brain regions, such as midbrain and cortex, which interact through feed-forward and feedback pathways. Hearing loss leads to a profound re-weighting of excitatory and inhibitory synaptic gain throughout the auditory CNS, and this is associated with an over-excitability that is observed in vivo. Further behavioral and computational analyses may provide insights into how theses cellular and systems plasticity effects underlie the development of cognitive functions such as speech perception

PURPOSE OF REVIEW: Sentinel node biopsy (SNB) is emerging as a potential tool to evaluate neck node metastasis in head and neck cancer. The purpose of this article is to undertake a systemic review of published literature and to outline future directions for further studies. RECENT FINDINGS: Existing data suggest that the status of the sentinel lymph node (SLN) predicts the pathologic stage of the nodal basin. It has been demonstrated that radiolabeled lymphoscintigraphy is superior to blue dye to localize the SLN in head and neck cancer. SLN biopsy should be recommended only in patients with previously untreated early stage (T1/2) oral cavity and orophparynx cancer with clinical N0 stage. The procedure is technique sensitive. The isolated SLN should be subjected to serial step sectioning at 150 microm and staining by hematoxylin and eosin and immunohistochemistry. Intraoperative frozen section and imprint cytology are not sensitive to identify small foci of micrometastasis and isolated tumor cells within the SLN. The clinical relevance of micrometastasis and isolated tumor cells needs to be established. It is necessary to develop a better method for intraoperative pathological confirmation of SLN metastasis. There exists no randomized clinical trial with adequate power that compares SNB and elective neck dissection in head and neck cancer. SUMMARY: SNB in head and neck squamous cell carcinoma should be considered as an investigational tool pending validation by larger randomized clinical trials; therefore, it should not be recommended at present outside a clinical trial setting.

Persistent oral ulcers and erosions can be the final common manifestation, sometimes clinically indistinguishable, of a diverse spectrum of conditions ranging from traumatic lesions, infectious diseases, systemic and local immune-mediated lesions up to neoplasms. The process of making correct diagnosis for persistent oral ulcers still represents a challenge to clinicians. Major diagnostic criteria should include the clinical appearance of both ulcer and surrounding non-ulcerated mucosa, together with the evaluation of associated signs and symptoms, such as: number (single or multiple), shape, severity of the ulcer(s), conditions of remaining mucosa (white, red or with vesiculo-bullous lesions) and systemic involvement (e.g. fever, lymphadenopathy or evaluation of haematological changes). The aim of this paper was to review the literature relating to persistent oral ulcers and provide a helpful, clinical-based diagnostic tool for recognising long-standing ulcers in clinical dental practice. The authors, therefore, suggest distinguishing simple, complex and destroying (S-C-D system) ulcerations, as each requires different diagnostic evaluations and management. This classification has arisen from studying the current English literature relating to this topic, performed using MEDLINE / PubMed / Ovid databases.

OBJECTIVES: We studied the effect of transforming growth factor (TGF)-beta on immortalized human vocal fold fibroblasts. METHODS: Normal human vocal fold fibroblasts were subjected to sequential lentiviral transduction with genes for human telomerase (hTERT) and SV40 large T antigen in order to produce an 'immortalized' cell line of normal phenotype. After confirmation of vocal fold fibroblast transfection, these cells, referred to as HVOX, were treated with various concentrations of exogenous TGF-beta1 and assayed for collagen secretion, migration, and proliferation. In addition, components of the TGF-beta signaling pathway were examined in this cell line. RESULTS: TGF-beta stimulated collagen secretion and migration without altering proliferation of HVOX. HVOX constitutively expressed type I and II TGF-beta receptors, as well as messenger RNA for the Smad signaling proteins and for all TGF-beta isoforms. Exogenous TGF-beta1 induced temporally dependent alterations in Smad2 and Smad3 gene expression. TGF-beta increased Smad7 expression at both 4 and 24 hours. Prolonged exposure to TGF-beta decreased TGF-beta1 gene expression. CONCLUSIONS: Insight into the underlying pathophysiology of vocal fold fibrosis is likely to yield improved therapeutic strategies to mitigate vocal fold scarring. Our data suggest that TGF-beta signaling may be both paracrine and autocrine in this vocal fold fibroblast cell line, and we therefore propose that TGF-beta may be a reasonable target for therapies to prevent and/or treat vocal fold fibrosis, given its putative role in both acute and chronic vocal fold injury, as well as its effects on vocal fold fibroblasts

A 48-year-old woman with a history of chronic intranasal cocaine abuse presented with unilateral proptosis associated with severe visual loss from optic neuropathy in the right eye. Imaging showed extensive bone and soft tissue destruction in the paranasal region and an orbital mass. Initial biopsies suggested a low-grade neoplasm. The correct diagnosis was established only on repeat biopsy, which revealed marked pleomorphism and nonspecific chronic inflammation with irregular collagen bundles containing thick-walled blood vessels. This case emphasizes that intranasal cocaine abuse may clinically, radiographically, and histopathologically mimic a neoplasm or a necrotizing vasculitis.

This paper presents an optimal path planning method of steerable electrode arrays for robot assisted cochlear implant surgery In this paper, the authors present a novel design of steerable electrode arrays that can actively bend at the up An embedded strand in the electrode array provides an active steering degrees of freedom (DoF) This paper addresses the calibration of the steerable electrode arrays and the optimal path planning for inserting it into planar and three dimensional scala tympani models The goal of the path planning is to minimize the intracochlear forces that the electrode array applies on the walls of the scala tympam during insertion This problem is solved by designing insertion path planning algorithms that provide best fit between the shape of the electrode aunty and the curved scala tympani during insertion Optimality measures that account fittape discrepancies between the steerable electrode array and the scala tympam are used to solve for the optimal path planning of the robot Different arrangements of DoF and insertion speed force feedback (ISFF) are simulated and experimentally validated in this paper A quality of insertion metric describing the gap between the steerable electrode array and the scala tympam model is presented and as correspondence to the insertion force is shown The results of using 1DoF 2DoF and 4DoF electrode array insertion setups are compared The 1DoE insertion setup fiver nonsteerable electrode arrays The 2DoF insertion setup uses single axis insertion with steerable electrode arrays. The 4DoF insertion setup allows full control of the insertion depth and the approach angle of the electrode with respect to the cochlea while using steerable electrode arrays It is shown that living steerable electrode arrays significantly reducer the maximal insertion force (59.6% or more) and effectively prevents buckling of the electrode array The 4DoF Insertion setup further reduces the maximal electrode insertion forces The results of using ISFF for steerable electrodes show a slight decrease in the insertion forcer in contrast to a slight increase for nonsteerable electrodes These results show that further research is required in order to determine the optimal ISFF control law and its effectiveness in reducing electrode invention fortes [DOI 10.1115/1.3039513]