Faculty Bibliography

G protein-coupled receptors (GPCRs) are the largest family of transmembrane signaling proteins. Within the gastrointestinal tract, GPCRs expressed by epithelial cells sense contents of the lumen, and GPCRs expressed by epithelial cells, myocytes, neurons, and immune cells participate in communication amongst cells. GPCRs control digestion, mediate digestive diseases, and coordinate repair and growth. GPCRs are the target of over one third of therapeutic drugs, including many drugs used to treat digestive diseases. Recent advances in structural, chemical, and cell biology research have revealed that GPCRs are not static binary switches that operate from the plasma membrane to control a defined set of intracellular signals. Rather, GPCRs are dynamic signaling proteins that adopt distinct conformations and subcellular distributions when associated with different ligands and intracellular effectors. An understanding of the dynamic nature of GPCRs has provided insights into the mechanism of activation and signaling of GPCRs, and has revealed opportunities for drug discovery. We review the allosteric modulation, biased agonism, oligomerization, and compartmentalized signaling of GPCRs that control digestion and digestive diseases. We highlight the implications of these concepts for the development of selective and effective drugs to treat diseases of the gastrointestinal tract.

BACKGROUND:Prompted by the revolution in high-throughput sequencing and its potential impact for treating cancer patients, we initiated a clinical research study to compare the ability of different sequencing assays and analysis methods to analyze glioblastoma tumors and generate real-time potential treatment options for physicians. METHODS:A consortium of seven institutions in New York City enrolled 30 patients with glioblastoma and performed tumor whole genome sequencing (WGS) and RNA sequencing (RNA-seq; collectively WGS/RNA-seq); 20 of these patients were also analyzed with independent targeted panel sequencing. We also compared results of expert manual annotations with those from an automated annotation system, Watson Genomic Analysis (WGA), to assess the reliability and time required to identify potentially relevant pharmacologic interventions. RESULTS:WGS/RNAseq identified more potentially actionable clinical results than targeted panels in 90% of cases, with an average of 16-fold more unique potentially actionable variants identified per individual; 84 clinically actionable calls were made using WGS/RNA-seq that were not identified by panels. Expert annotation and WGA had good agreement on identifying variants [mean sensitivity = 0.71, SD = 0.18 and positive predictive value (PPV) = 0.80, SD = 0.20] and drug targets when the same variants were called (mean sensitivity = 0.74, SD = 0.34 and PPV = 0.79, SD = 0.23) across patients. Clinicians used the information to modify their treatment plan 10% of the time. CONCLUSION/CONCLUSIONS:These results present the first comprehensive comparison of technical and machine augmented analysis of targeted panel and WGS/RNA-seq to identify potential cancer treatments.

OBJECTIVE:To determine adverse events after endoscopic flexible vs endoscopic rigid cricopharyngeal myotomy for treatment of Zenker's diverticulum (ZD). DATA SOURCES/METHODS:Systematic review of MEDLINE, Web of Science, CINAHL, Clinicaltrials.gov, and Cochrane Central Register of Controlled Trials for all years according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Additional studies were identified from review citations and a by hand search of manuscripts referencing ZD. REVIEW METHODS/METHODS:A structured literature search was conducted to identify studies for this systematic review. Methodological Index for Non-randomized Studies (MINORS) criteria were applied to assess study quality. For inclusion, each study had to provide data for at least 10 adult patients who had undergone endoscopic ZD repair reporting clear association with the postprocedure course in each case. Data extracted included all reported adverse events, recurrences, follow-up, and operative times. RESULTS:In total, 115 studies were included. All but 8 were retrospective case series. Sixty-one reported series of patients after rigid endoscopic stapler repair, 31 after rigid laser repair, and 13 with other rigid endoscopic instruments. Twenty-nine flexible endoscopic studies were included. Mortality, infection, and perforation were not significantly more likely in either the rigid or the flexible group, but bleeding and recurrence were more likely after flexible endoscopic techniques (20% vs <10% and 4% vs 0%, respectively). Dental injury and vocal fold palsy were reported rarely in the rigid endoscopic groups. CONCLUSIONS:Adverse events are rare after endoscopic Zenker's repair. The flexible approach minimizes exposure limitations and can be completed in some patients without general anesthesia. Transoral rigid approaches result in fewer revision surgeries compared with flexible diverticulotomy.

Neural representations of the external world are constructed and updated in a manner that depends on behavioral context. For neocortical networks, this contextual information is relayed by a diverse range of neuromodulatory systems, which govern attention and signal the value of internal state variables such as arousal, motivation, and stress. Neuromodulators enable cortical circuits to differentially process specific stimuli and modify synaptic strengths in order to maintain short- or long-term memory traces of significant perceptual events and behavioral episodes. One of the most important subcortical neuromodulatory systems for attention and arousal is the noradrenergic locus coeruleus. Here we report that the noradrenergic system can enhance behavior in rats performing a self-initiated auditory recognition task, and optogenetic stimulation of noradrenergic locus coeruleus neurons accelerated the rate at which trained rats began correctly responding to a change in reward contingency. Animals successively progressed through distinct behavioral epochs, including periods of perseverance and exploration that occurred much more rapidly when animals received locus coeruleus stimulation. In parallel, we made recordings from primary auditory cortex and found that pairing tones with locus coeruleus stimulation led to a similar set of changes to cortical tuning profiles. Thus both behavioral and neural responses go through phases of adjustment for exploring and exploiting environmental reward contingencies. Furthermore, behavioral engagement does not necessarily recruit optimal locus coeruleus activity.

Skill learning is fundamental to the acquisition of many complex behaviors that emerge during development. For example, years of practice give rise to perceptual improvements that contribute to mature speech and language skills. While fully honed learning skills might be thought to offer an advantage during the juvenile period, the ability to learn actually continues to develop through childhood and adolescence, suggesting that the neural mechanisms that support skill learning are slow to mature. To address this issue, we asked whether the rate and magnitude of perceptual learning varies as a function of age as male and female gerbils trained on an auditory task. Adolescents displayed a slower rate of perceptual learning as compared to their young and mature counterparts. We recorded auditory cortical neuron activity from a subset of adolescent and adult gerbils as they underwent perceptual training. While training enhanced the sensitivity of most adult units, the sensitivity of many adolescent units remained unchanged, or even declined across training days. Therefore, the average rate of cortical improvement was significantly slower in adolescents as compared to adults. Both smaller differences between sound-evoked response magnitudes and greater trial-to-trial response fluctuations contributed to the poorer sensitivity of individual adolescent neurons. Together, these findings suggest that elevated sensory neural variability limits adolescent skill learning.Significance Statement:The ability to learn new skills emerges gradually as children age. This prolonged development, often lasting well into adolescence, suggests that children, teens, and adults may rely on distinct neural strategies to improve their sensory and motor capabilities. Here, we found that practice-based improvement on a sound detection task is slower in adolescent gerbils than in younger or older animals. Neural recordings made during training revealed that practice enhanced the sound sensitivity of adult cortical neurons, but had a weaker effect in adolescents. This latter finding was partially explained by the fact that adolescent neural responses were more variable than in adults. Our results suggest that one mechanistic basis of adult-like skill learning is a reduction in neural response variability.

Chronic inflammation of the salivary glands from pathologic conditions such as Sjögren's syndrome can result in glandular destruction and hyposalivation. To understand which molecular factors may play a role in clinical cases of salivary gland hypofunction, we developed an aquaporin 5 (AQP5) Cre mouse line to produce genetic recombination predominantly within the acinar cells of the glands. We then bred these mice with the TNF-αglo transgenic line to develop a mouse model with salivary gland-specific overexpression of TNF-α; which replicates conditions seen in sialadenitis, an inflammation of the salivary glands resulting from infection or autoimmune disorders such as Sjögren's syndrome. The resulting AQP5-Cre/TNF-αglo mice display severe inflammation in the salivary glands with acinar cell atrophy, fibrosis, and dilation of the ducts. AQP5 expression was reduced in the salivary glands, while tight junction integrity appeared to be disrupted. The immune dysregulation in the salivary gland of these mice led to hyposalivation and masticatory dysfunction.

Perineural invasion (PNI), the neoplastic invasion of nerves, is a common pathological finding in head and neck cancer that is associated with poor clinical outcomes. PNI is a histological finding of tumor cell infiltration and is distinct from perineural tumor spread (PNTS), which is macroscopic tumor involvement along a nerve extending from the primary tumor that is by definition more advanced, being radiologically or clinically apparent. Despite widespread acknowledgement of the prognostic significance of PNI/PNTS, the mechanisms underlying its pathogenesis remain largely unknown, and specific therapies targeting nerve invasion are lacking. The use of radiation therapy for PNI/PNTS can improve local control and reduce devastating failures at the skull base. However, the optimal volumes to be delineated with respect to targeting cranial nerve pathways are not well defined, and radiation may carry risks of major toxicity secondary to the location of adjacent critical structures. Here we examine the pathogenesis of these phenomena, analyze the role of radiation in PNI/PNTS, and propose guidelines for radiation treatment design based on the best available evidence and the authors' collective experience in order to advance understanding and therapy of this ominous cancer phenotype.

A cochlear implant (CI) is a surgically implanted device for the treatment of severe to profound sensorineural hearing loss in children and adults. It works by transducing acoustic energy into an electrical signal, which is used to stimulate surviving spiral ganglion cells of the auditory nerve. The past 2 decades have witnessed an exponential rise in the number of CI surgeries performed. Continual developments in programming strategies, device design, and minimally traumatic surgical technique have demonstrated the safety and efficacy of CI surgery. As a result, candidacy guidelines have expanded to include both pre and postlingually deaf children as young as 1 year of age, and those with greater degrees of residual hearing. A growing proportion of patients are undergoing CI for off-label or nontraditional indications including single-sided deafness, retrocochlear hearing loss, asymmetrical sensorineural hearing loss (SNHL) in adults and children with at least 1 ear that is better than performance cut-off for age, and children less than 12 months of age. Herein, we review CI design, clinical evaluation, indications, operative technique, and outcomes. We also discuss the expanding indications for CI surgery as it relates to lateral skull base pathology, comparing CI to auditory brainstem implants, and address the concerns with obtaining magnetic resonance imaging (MRI) in CI recipients.

OBJECTIVES/OBJECTIVE:Adequate treatment of laryngopharyngeal malignancy often incorporates radiation therapy. Structures surrounding laryngopharynx exposed to traditional radiation doses are susceptible to posttreatment toxicity. Among poorly understood sequelae is the rare manifestation of sternoclavicular joint (SCJ) osteoradionecrosis (ORN). METHODS:Three institutional encounters prompted a comprehensive literature search, generating three published case reports. Systematic extraction and analysis (n = 6) of demographics, cancer history, comorbidities, ORN presentation, imaging, and management established the largest series to investigate this pathology. RESULTS:Patients were males (6), 54 to 70 years old, smokers (4), with Hypertension/dyslipidemia, myocardial infarction/coronary artery disease, second primary (2), diabetes mellitus (1), and myelofibrosis(1). Four underwent total laryngectomy, one primary, three as salvage. Five patients had concurrent chemoradiation (≥70 Gy). All patients presented with swollen, tender neck wounds concerning for persistent/recurrent malignancy. Computed tomography (CT) demonstrated bone erosion (5 of 5) and increased bone scan uptake (2 of 2). All responded to surgical exploration with drainage alone (1), sequestrectomy (2), or bone resection with synovectomy (3). Complete healing took 2 months to 3 years. One unrelated patient death occurred before control of ORN was achieved. DISCUSSION/CONCLUSIONS:Given varied patient characteristics, synergistic risk factors exist that alter bone radiation threshold, resulting in irreversible ischemic damage and osteoradionecrosis. Vascular susceptibility and inability to repair may regulate that threshold. Understanding this relationship will facilitate early detection and intervention. CONCLUSION/CONCLUSIONS:Integrating cases of sternoclavicular joint ORN promotes awareness of atypical laryngopharyngeal radiation complications, elucidates contributing factors, educates physicians on presentation and management, and provides a platform for prospective investigation. LEVEL OF EVIDENCE/METHODS:4. Laryngoscope, 2018.