Faculty Bibliography

OBJECTIVES/OBJECTIVE:The auditory experience of early deafened pediatric cochlear implant (CI) users is different from that of postlingually deafened adult CI users due to disparities in the developing auditory system. It is therefore expected that the auditory psychophysical capabilities between these two groups would differ. In this study, temporal resolving ability was investigated using a temporal modulation detection task to compare the performance outcomes between these two groups. DESIGN/METHODS:The minimum detectable modulation depth of amplitude modulated broadband noise at 100 Hz was measured for 11 early deafened children with a CI and 16 postlingually deafened adult CI users. RESULTS:Amplitude modulation detection thresholds were significantly lower (i.e., better) for the pediatric CI users than for the adult CI users. Within each group, modulation detection thresholds were not significantly associated with chronologic age, age at implantation, or years of CI experience. CONCLUSIONS:Early implanted children whose auditory systems develop in response to electric stimulation demonstrate better temporal resolving abilities than postlingually deafened adult CI users. This finding provides evidence to suggest that early implanted children might benefit from sound coding strategies emphasizing temporal information.

Bone cancer metastasis is extremely painful and decreases the quality of life of the affected patients. Available pharmacological treatments are not able to sufficiently ameliorate the pain and as cancer patients are living longer new treatments for pain management are needed. Decitabine (5-aza-2'-deoxycytidine), a DNA methyltransferases inhibitor, has analgesic properties in pre-clinical models of post-surgical and soft tissue oral cancer pain by inducing an up-regulation of endogenous opioids. In this study, we report that daily treatment with decitabine (2µg/g, i.p.) attenuated nociceptive behavior in the 4T1-luc2 mouse model of bone cancer pain. We hypothesized that the analgesic mechanism of decitabine involved activation of the endogenous opioid system through demethylation and reexpression of the transcriptionally silenced endothelin B receptor gene, Ednrb. Indeed, Ednrb was hypermethylated and transcriptionally silenced in the mouse model of bone cancer pain. We demonstrated that expression of Ednrb in the cancer cells lead to release of β-endorphin in the cell supernatant which reduced the number of responsive DRG neurons in an opioid-dependent manner. Our study supports a role of demethylating drugs, such as decitabine, as unique pharmacological agents targeting the pain in the cancer microenvironment.

BACKGROUND:Measurement of the angular depth of insertion (aDOI) of cochlear implant electrode arrays has numerous clinical and research applications. Plain-film radiographs are easily obtained intraoperatively and have been described as a means to calculate aDOI. CT imaging with 3D reformatting can also be used for this measurement, but is less conveniently obtained and requires higher radiation doses, a particular concern in pediatrics. The extent to which plain-film and 3D CT image-based measurements are representative of the true position of the electrode within the cochlea is unknown. METHODS:Cochlear implantation was performed on 10 cadaveric temporal bones. Five bones were implanted with perimodiolar electrodes (Contour Advance TM, Cochlear, Sydney, Australia) and five were implanted with lateral wall electrodes (Slim Straight, Cochlear). The insertion depths of the electrodes were varied. Each bone was imaged with a radiograph and CT. aDOI was measured for each bone in each imaging modality by a neurotologist and a neuroradiologist. To obtain a 'gold standard' estimate of aDOI, the implanted temporal bones were embedded in an epoxy resin and methodically sectioned at 100 μm intervals; histologic images were captured at each interval. A 3D stack of the images was compounded, and a MATLAB script used to calculate aDOI of the most apical electrode. Measurements in the three modalities (radiograph, CT, and histology) were then compared. RESULTS:The average aDOI across all bones was similar for all modalities: 423° for radiographs, 425° for CT scans, and 427° for histology, indicating that neither imaging modality resulted in large systematic errors. Using the histology-measured angles as a reference, the average error for CT-based measures (regardless of whether the error was in the positive or negative direction) was 12°, and that for radiograph-based measures was 15°. This small difference (12 vs 15° error) was not statistically significant. CONCLUSION/CONCLUSIONS:Based on this cadaveric temporal bone model, both radiographs and CTs can provide reasonably accurate aDOI measurements. In this small sample, and as expected, the CT-based estimates were more accurate than the radiograph-based measurements. However, the difference was small and not statistically significant. Thus, the use of plain radiographs to calculate aDOI seems judicious whenever it is desired to prevent unnecessary radiation exposure and expense.

Introduction: Vagus nerve stimulation is currently used as a medical treatment for those suffering from severe epilepsy or depression, but the mechanisms underlying vagus nerve stimulation are poorly understood. The vagus nerve helps connect essentially all peripheral organs to the central nervous system, sending afferents to the nucleus tractus solitarius. Recent studies indicate that vagus nerve stimulation can produce long-lasting plasticity in the cerebral cortex, leading to improved sensory processing and recovery of motor behavior after stroke (Boreland et al, Brain Stimul (2016). An understanding of the circuit mechanisms by which vagus nerve stimulation can produce these results would be important for enhancing behavioral outcomes and developing less invasive or non-invasive neuromodulatory therapeutic techniques. Method(s): Studies in mice provide an opportunity for monitoring and manipulating various aspects of neural circuits involved in behavior. One difficulty in the mouse model is the lack of vagus nerve cuff electrodes given the small size of the mouse vagus nerve. We first built a novel vagus nerve cuff electrode for mice and demonstrated reliable low-impedance recordings and stimulation during behavior in mice chronically implanted for months. Two-photon imaging of the auditory cortex was used to track neural responses to tones paired with vagus nerve stimulation. Animals are then trained on either a paired go/no-go or two-alternative forced choice auditory detection and recognition task (Martins and Froemke, Nat Neurosci 2015; Kuchibhotla et al. Nat Neurosci 2017). Result(s): Stimulation of the vagus nerve was calibrated to transiently reduce respiration without affecting other physiological processes (e.g., heart rate). Using two-photon imaging, we found that pairing target tones with vagus nerve stimulation for five minutes led to a short-term enhancement of sensory responses in the mouse auditory cortex. After several days of these brief 5-minute pairing sessions, long-term plasticity was observed with increases in representation of the target tone for at least days thereafter. Conclusion(s): These changes are reminiscent of the effects of basal forebrain stimulation (Froemke et al. Nature 2007) and we are now investigating how vagus nerve stimulation might lead to direct or indirect activation of central modulatory systems to improve plasticity and behavior in mice.

Introduction: The mammalian enteric nervous system (ENS) regulates intestinal function in response to luminal changes in nutrients and microbiota. The ENS also modulates immune cells to control microbial homeostasis and fight infections. Enteric neurons signal to the brain via the vagus nerve, providing a mechanism by which microbiota can influence neural activity and behavior at homeostasis or during infections with gut pathogens. However, little is known about the relation between vagus nerve activity and 'sickness behaviors' such as decreased attention, increased irritability and depression, and decreased interest and energy. Here we aimed to record vagus nerve responses in behaving animals towards understanding this gut-brain signaling connection in sickness behavior. Method(s): Custom nerve cuff electrodes were used to monitor vagus nerve activity of wild-type male mice. Cuffs were made with 0.2 mm micro-renathane tubing to surround the upper branch of the sensory vagus nerve and connected to socket gold pins and medwire. Chronic nerve cuffs were implanted in mice aged 6-12 weeks. Surgery consisted of securing gold pins to the cranial vertex and connecting electrodes to the vagus nerve in the neck, around which the cuff was placed. The grounding wire was secured near the cuff. One to two weeks post-surgery, each mouse underwent sickness induction via lipopolysaccharide (LPS) injection. LPS solution was formulated with 9.5/g muL of 0.9% saline solution and 0.5/g muL of pure LPS via intraperitoneal injection. Electrophysiological activity of the vagus nerve was recorded together with video monitoring of behavior, prior to injection to first establish a baseline, and post-injection activity was recorded for up to 24 hours. Sickness behavior was ethogrammed and neural activity analyzed in each animal. Result(s): LPS injection led to reduction of several different behaviors including overall motion in the homecage for hours afterwards. Analysis of simultaneously-recorded vagus activity is ongoing. Conclusion(s): We here describe an integrated system that combines long-term videography and behavioral analysis with recordings of the peripheral nerve activity using a custom chronic nerve cuff for the mouse vagus. Using this system, we have begun to relate neural activity in the sensory vagus to physiological state and behavioral changes in mice for the first time.

Purpose Although vocal training is often purported to restore and rebalance laryngeal muscle function, little is known about the direct effects of vocal training on the laryngeal muscles themselves. Consequently, parameters of vocal exercise dose, such as training duration and intensity, have not been well defined. The goal of this study was to use a behavioral animal model to determine the effects of short- and long-term ultrasonic vocalization (USV) training on USV acoustics, thyroarytenoid (TA) muscle neuromuscular junctions (NMJs), and TA muscle fiber size in adult rats. Method Twenty-four young adult male Long-Evans rats were divided into 3 groups (untrained control, 4-week training, and 8-week training). Baseline and posttraining USVs were recorded and acoustically analyzed for fundamental frequency, frequency bandwidth, amplitude, and duration. Presynaptic and postsynaptic NMJ morphological features and muscle fiber size were measured in the TA. Results USV training had no effect on USV acoustics. Eight weeks of USV training, however, resulted in a lower NMJ motor endplate dispersion ratio, consistent with previous findings. USV training did not affect fiber size within the TA muscle. Conclusions This study demonstrated that 8 weeks of USV training can induce peripheral neural adaptations in the NMJ of the TA muscle in young rats. The observed adaptations suggest that vocal training is consistent with endurance-type exercise, but the adaptations occur on a longer time scale than similar adaptations in the limb muscles.

Introduction/UNASSIGNED:Inhalation injury is an independent risk factor in burn mortality, imparting a 20% increased risk of death. Yet there is little information on the natural history, functional outcome, or pathophysiology of thermal injury to the laryngotracheal complex, limiting treatment progress. Methods/UNASSIGNED:Case series (n=3) of significant thermal airway injury. Results/UNASSIGNED:In all cases, the initial injury was far exceeded by the subsequent immune response and aggressive fibro-inflammatory healing. Serial examination demonstrated progressive epithelial injury, mucosal inflammation, airway remodeling, and luminal compromise. Histologic findings in the first case demonstrate an early IL-17A response in the human airway following thermal injury. This is the first report implicating IL-17A in the airway mucosal immune response to thermal injury. Our 2nd and 3rd patients received Azithromycin targeting IL-17A and showed clinical responses. The third patient also presented with exposed tracheal cartilage and underwent mucosal reconstitution via split-thickness skin graft over an endoluminal stent in conjunction with tracheostomy. This was associated with rapid abatement of mucosal inflammation, resolution of granulation tissue and return of laryngeal function. Conclusion/UNASSIGNED:Patients who present with thermal inhalation injury should receive a thorough multidisciplinary airway evaluation, including early otolaryngologic evaluation. New early endoscopic approaches (scar lysis, and mucosal reconstitution with autologous grafting over an endoluminal stent), when combined with targeted medical therapy aimed at components of mucosal airway inflammation (local corticosteroids and systemic Azithromycin targeting IL-17A) may have potential to limit chronic cicatricial complications.

PURPOSE/OBJECTIVE:Isocitrate dehydrogenase (IDH) mutant gliomas are a distinct glioma molecular subtype for which no effective molecularly-directed therapy exists. Low-grade gliomas, which are 80-90% IDH mutant, have high RNA levels of the cell surface Notch ligand DLL3. We sought to determine DLL3 expression by immunohistochemistry in glioma molecular subtypes and the potential efficacy of an anti-DLL3 antibody drug conjugate (ADC), rovalpituzumab tesirine (Rova-T), in IDH mutant glioma. EXPERIMENTAL DESIGN/METHODS:We evaluated DLL3 expression by RNA using TCGA data and by immunohistochemistry in a discovery set of 63 gliomas and 20 non-tumor brain tissues and a validation set of 62 known IDH wildtype and mutant gliomas using a monoclonal anti-DLL3 antibody. Genotype was determined using a DNA methylation array classifier or by sequencing. The effect of Rova-T on patient-derived endogenous IDH mutant glioma tumorspheres was determined by cell viability assay. RESULTS:Compared to IDH wildtype glioblastoma, IDH mutant gliomas have significantly higher DLL3 RNA (P<1x10-15) and protein by immunohistochemistry (P=0.0014 and P<4.3x10-6 in the discovery and validation set, respectively). DLL3 immunostaining was intense and homogeneous in IDH mutant gliomas, retained in all recurrent tumors, and detected in only 1 of 20 non-tumor brains. Patient-derived IDH mutant glioma tumorspheres overexpressed DLL3 and were potently sensitive to Rova-T in an antigen-dependent manner. CONCLUSIONS:DLL3 is selectively and homogeneously expressed in IDH mutant gliomas and can be targeted with Rova-T in patient-derived IDH mutant glioma tumorspheres. Our findings are potentially immediately translatable and have implications for therapeutic strategies that exploit cell surface tumor-associated antigens.

This evaluation of quality metrics uses data from the National Cancer Database to summarize hospital-level overall quality of care for patients with head and neck cancer in the United States.