Role of C3a as a Novel Regulator of 25(OH)D3 to 1α,25-Dihydroxyvitamin D3 Metabolism in Upper Airway Epithelial Cells.

In patients with chronic rhinosinusitis with nasal polyps, primary human sinonasal epithelial cell (HSNEC) 1α-hydroxylase levels are reduced, as is their ability to metabolize 25-hydroxycholecalciferol [25(OH)D3] to its active metabolite, 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3]. In this study, we sought to identify the factor responsible for the regulation of HSNEC metabolism of 25(OH)D3, focusing on C3 and C3a. Multiple inhaled irritants trigger the release of complement components, C3 and C3a, leading to suppression of 1α-hydroxylase levels in HSNECs. Recombinant C3a was able to decrease 1α-hydroxylase and impair 25(OH)D3 to 1,25(OH)2D3 metabolism, while addition of a C3a receptor antagonist restored conversion. Conversely, 1,25(OH)2D3 suppressed Aspergillus fumigatus-induced C3 and C3a levels in HSNEC supernatant. Given the ability of 1,25(OH)2D3 to modulate LL37 in other cell types, we examined its regulation in HSNECs and relationship to C3a. 1,25(OH)2D3 stimulated the secretion of LL37, whereas A. fumigatus and C3a suppressed it. Conversely, LL37 reduced the release of C3/C3a by HSNECs. Lastly, oral steroid use and in vitro dexamethasone application both failed to increase 1α-hydroxylase or reduce C3a levels. In summary, in this article, we describe for the first time a novel relationship between complement activation and local vitamin D metabolism in airway epithelial cells. The presence of elevated C3/C3a in patients with asthma and/or chronic rhinosinusitis with nasal polyps may account for their impaired HSNEC 25(OH)D3 to 1,25(OH)2D3 metabolism and explain why they receive limited therapeutic benefit from oral vitamin D3 supplementation.

Use of Water Proton NMR to Characterize Protein Aggregates: Gauging the Response and Sensitivity.

Water proton transverse relaxation rate R2(1H2O) measurements by NMR stand out as a powerful noninvasive tool to detect protein aggregates, including subvisible particles in biopharmaceutical formulations. To understand the applicability of water proton NMR ( wNMR), we studied the response and sensitivity of wNMR to the aggregates of a monoclonal antibody (mAb) within a wide size range at different aggregate levels, for three different physical stresses: freeze-thaw cycling, heating, and agitation. We compared the sensitivity and response of wNMR with those observed by conventional techniques of size exclusion chromatography (SEC), microflow imaging (MFI), and dynamic light scattering (DLS). Our findings showed that wNMR detects mAb aggregates within wide aggregate levels and in a wide range of aggregate sizes. wNMR was sensitive to an increase in soluble protein aggregates in the range of <1.0%. In most cases, wNMR demonstrated linear response toward the aggregate fraction. Nonlinearity of such response potentially points to the presence of larger size aggregates that possibly rearrange and/or dissociate upon dilution. The results demonstrate the potential of wNMR as a quantitative and noninvasive analytical tool for characterizing protein aggregates in biopharmaceutical formulations.

Water Proton NMR: A Tool for Protein Aggregation Characterization.

Formulation stability is a critical attribute of any protein-based biopharmaceutical drug due to a protein's inherent tendency to aggregate. Advanced analytical techniques currently used for characterization of protein aggregates are prone to a number of limitations and usually require additional manipulations with the sample, such as dilution, separation, labeling, and use of special cuvettes. In the present work, we compared conventional techniques for the analysis of protein aggregates with a novel approach that employs the water proton transverse relaxation rate R2(1H2O). We explored differences in the sensitivity of conventional techniques, size-exclusion chromatography (SEC), microflow imaging (MFI), and dynamic light scattering (DLS), and water NMR (wNMR) toward the presence of monoclonal antibody aggregates generated by different stresses. We demonstrate that wNMR outperformed SEC, DLS, and MFI in that it was most consistently sensitive to increases in both soluble and insoluble aggregates, including subvisible particles. The simplicity of wNMR, its sensitivity, and possibility of noninvasive measurements are unique advantages that would permit its application for more efficient and higher throughput optimization of protein formulations.

Plasmonic measurements of monoclonal antibody self-association using self-interaction nanoparticle spectroscopy.

One of the most significant challenges in developing therapeutic monoclonal antibodies (mAbs) is their unpredictable solubilities and viscosities at the high concentrations required for subcutaneous delivery. This challenge has motivated the development of screening assays that rapidly identify mAb variants with minimal self-association propensities and/or formulation conditions that suppress mAb self-association. Here we report an improved version of self-interaction nanoparticle spectroscopy (SINS)capable of characterizing both repulsive and attractive self-interactions between diverse mAbs. The basis of SINS is that self-interactions between mAbs immobilized on gold nanoparticles increase (repulsion) or decrease (attraction)interparticle distances, which shift the wavelength of maximum absorbance (plasmon wavelength) in opposite directions.We find that the robustness of SINS is improved by varying the amount of immobilized mAb by co-adsorbing a polyclonal antibody. The slopes of the plasmon wavelength shifts as a function of the amount of immobilized mAb (0.01­0.1 mg/mL) are correlated with diffusion interaction parameters measured at two to three orders of magnitude higher antibody concentrations. The ability of SINS to rapidly screen mAb self-association in a microplate format using dilute mAb solutions makes it well suited for use in diverse settings ranging from antibody discovery to formulation.

Regulatory and Implementation Considerations for Artificial Intelligence.

Successful artificial intelligence (AI) implementation is predicated on the trust of clinicians and patients, and is achieved through a culture of responsible use, focusing on regulations, standards, and education. Otolaryngologists can overcome barriers in AI implementation by promoting data standardization through professional societies, engaging in institutional efforts to integrate AI, and developing otolaryngology-specific AI education for both trainees and practitioners.

Management of the Nasolacrimal Duct in Expanded Endoscopic Approaches to the Maxillary Sinus: A Systematic Review with Evidence-based Recommendations.

BACKGROUND: Utilizing expanded endoscopic approaches to the maxillary sinus for the endonasal management of a variety of tumors is increasing in popularity. The nasolacrimal duct (NLD) may be injured inadvertantly or need to be removed during tumor resection or to augment visualization. Management of the NLD can take the form of transection alone, transection with stenting, or performing a formal dacryocystorhinostomy to avoid postoperative sequelae of injury. The purpose of this study was to review the literature and determine the optimal management of the NLD during expanded maxillary sinus approaches. METHODS: A systematic review of Ovid, Embase, Medline, and Cochrane databases was performed to identify studies involving expanded approaches to the maxillary sinus and that explicitly reported the status of the NLD and postoperative outcomes. RESULTS: Nineteen studies were included in the analysis and divided into two groups: NLD-preserving (n = 9 studies; n = 191 patients in aggregate) and NLD-involving (n = 10 studies; n = 296 patients in aggregate). In the NLD-preserving subgroup, one patient out of a subgroup aggregate of 191 patients (0.5%) developed epiphora. In the NLD-involving subgroup, sharp transection alone was the most common method of NLD removal and was associated with a low rate of epiphora (study rates: 0 to 18.2%; aggregated subgroup rate: 7.0%, 21 / 296). Spontaneous resolution of symptoms was common (60%-100% cases). CONCLUSIONS: The NLD should be preserved when feasible from an exposure and tumor-control perspective. When pathology or approach requires the removal of the NLD, rates of persistent epiphora are very low, regardless of surgical technique. When expanded maxillary approaches are employed, particularly for benign tumors, and require removal of the NLD, sharp transection is the simplest method of removal, provides a low rate of postoperative epiphora, and is supported by the available literature.

Sinonasal and Skull Base Metastatic Renal Cell Carcinoma: A Case Series.

Metastatic lesions to the paranasal sinuses and skull base, while rare, carry a poor prognosis. Renal cell carcinoma has been reported in multiple case reports to be one of the most common distant malignancies to spread to the paranasal sinuses; however, it is often unrecognized by physicians, and thus treatment is delayed. To increase awareness of this disease process, we describe three cases of metastatic renal cell carcinoma to the sinonasal cavity, which is the largest case series in the literature to date.

Non-tuberculous Mycobacterium Rhinosinusitis in an Immunocompetent Patient.

Non-tuberculous mycobacteria (NTM) are slow-growing opportunistic pathogens that cause a variety of cutaneous, soft tissue, and pulmonary infections. On rare occasions, NTM causes chronic rhinosinusitis, with the majority of cases presenting in immunocompromised individuals. Other potential risk factors include the presence of foreign bodies, previous sinus surgery or chemoradiation, and use of contaminated water in sinus rinses. We report here a rare case of NTM rhinosinusitis in an otherwise immunocompetent 66-year-old female. The patient underwent functional endoscopic sinus surgery where intraoperative acid-fast bacteria cultures grew Mycobacterium abscessus. She received five weeks of broad-spectrum IV antibiotic therapy followed by three months of oral azithromycin, tigecycline, and linezolid. A one-year post-operative visit showed appropriate healing without crusting or visible infection. This case contributes to the small handful of documented presentations of NTM rhinosinusitis in immunocompetent patients. NTM should be considered when patients present with refractory rhinosinusitis as they may require extended courses of antibiotic treatment. Familiarity with risk factors can further expedite making a diagnosis, ensuring prompt initiation of treatment and relief of symptoms for patients.

The Transverse Turbinate Line: A Reliable Landmark for the Maxillary Sinus Natural Ostium.

OBJECTIVES: Approximating the maxillary sinus natural ostium's (MSNO) natural position during anterograde surgery is challenging, as only a single visual "landmark," the maxillary line, is routinely offered to guide the identification of the MSNO in three-dimensional space. Despite almost 40 years of endoscopic sinus surgery (ESS) experience in North America, maxillary recirculation and discontinuity between the natural and surgical ostia are commonly encountered during revision ESS. Consequently, we feel an additional visual landmark would assist in localizing the MSNO with or without image guidance. In this study, we aim to provide a second reliable landmark in the sinonasal cavity. METHODS: We present a cadaveric anatomical landmark series that provides a second visual landmark for the MSNO, which we have labeled the transverse turbinate line (TTL): a 2-millimeter zone of confidence for the craniocaudal positioning of the MSNO that can be combined with the anteroposterior (AP) landmark of the maxillary line. RESULTS: In our study, 40 cadaveric sinuses were dissected, and the TTL was found to correspond consistently with the zone between the superior and inferior aspects of the MSNO. CONCLUSION: We anticipate that this second relational landmark may decrease the time required for anterograde access to the MSNO in trainees, increase the accuracy of identification, and translate to lower long-term recirculation and maxillary surgery failure rates. LEVEL OF EVIDENCE: NA Laryngoscope, 133:3285-3291, 2023.

Utilization of Nasal Mucus to Investigate the Pathophysiology of Chronic Rhinosinusitis.

BACKGROUND: Nasal mucus is proving to be a useful means by which to study the pathogenesis of chronic rhinosinusitis (CRS). Given the increase in publications examining nasal mucus and the lack of a review on this topic, we will focus on this noninvasive approach to studying CRS. Particular attention will be drawn towards inflammatory cytokines and biomarkers and their influence on disease severity. METHODS: A literature review of papers published in English pertaining to nasal mucus was performed using the PubMed database. The search utilized combinations of the following keywords: sinusitis, polyps, sample collection, nasal mucus, or nasal secretion. Studies solely on acute or bacterial sinusitis, allergic rhinitis, or cystic fibrosis were not included. RESULTS: A wide variety of materials and methods have been used to collect nasal mucus. Numerous assay types have been performed with the most common being ELISA, cytometric bead array, and proteomics. Most studies have focused on examining the levels of Th1/Th2 cytokines along with chemokines associated with type 2 immunity. Other factors identified include growth factors, senescence-associated proteins, complement, and antimicrobial defenses have also been identified. Nasal mucus cytokines have proven useful in cluster analysis and predicting postoperative improvement in Sino-nasal Outcome Test (SNOT-22) scores. One limitation of the use of nasal mucus is that some studies have suggested that nasal mucus does not always reflect the tissue microenvironment. CONCLUSIONS: Nasal mucus represents a critical tool by which to examine the sinonasal microenvironment in a noninvasive manner. Unlike studies of tissue, it can be utilized in both surgically and medically managed patients and avoids the trauma of biopsies. However, studies are still needed to determine the most effective method for nasal mucus collection. Studies should also take care to confirm that nasal mucus markers do, in fact, reflect the levels of the product studied in the tissue.

Sinonasal IgG4-related sclerosing disease: A rare entity and challenging diagnosis.

Objectives: To describe the rare presentation, imaging and histological findings, and treatments in patients with IgG4-related disease (IgG4-RD) and diagnostic pitfalls and difficulties. Methods: Cases of sinonasal IgG4-RD were retrieved, and clinicopathological features were reviewed. Results: Seven cases of sinonasal IgG4-RD were identified over an 11-year period, including four males and three females, with an age range of 19-66 years (median 58 years). Patients presented with symptoms related to the mass effect of the lesions or the destructive nature of the disease including fullness, swelling, obstruction, and pain. Serum IgG and IgG4 levels, IgG/IgG4 ratios, storiform fibrosis, obliterative phlebitis, and plasma cell infiltration were seen in varying proportions. Bony erosion and tissue inflammation were present in some cases. Conclusion: Sinonasal IgG4-RD is exceedingly rare among other IgG4-RD and varied in its clinical presentation thus posing as a clinically difficult disease to diagnosis. Proper clinical, pathological, and immunohistopathological analysis is required for accurate diagnosis. Such disease should be considered in all cases of similar presentation to those in this study.Level of Evidence: 4.

Curvularia and the Brain: Case Demonstration of Optimal Management.

Background: Curvularia is a ubiquitous fungus found in tropical climates and has been reported to grow on marijuana leaves. Rarely, it can infect humans and propagate from the nasal sinuses into the brain. Case: A 28-year-old immunocompetent patient presented with history of nasal polyps, headache, and subtle visual deficits on the right. Imaging revealed what appeared to be an invasive mass growing through the ethmoid and sphenoid sinuses into the anterior cranial fossa. Results: Otolaryngology performed an endoscopic nasal biopsy with pathology and cultures consistent for Curvularia (figure 6). A combination case with neurosurgery and otolaryngology was planned. Surgeons used a bifrontal craniotomy and endonasal approach for gross total resection. Following resection, the patient was placed on 4 weeks of amphotericin treatment followed by 12 months of voriconazole based on recommendations by infectious disease. The patient has been stable since surgery. Conclusion: Curvularia is a rare but potentially life threatening central nervous system infection that can be acquired from inhalational marijuana use. This illustrative case shows the importance of aggressive debridement followed by broad spectrum antifungal treatment to optimize outcome. With marijuana's increasing popularity, Curvalaria should be included on the differential diagnosis.

Characterization of a Novel Bispecific Antibody With Improved Conformational and Chemical Stability.

Bispecific antibodies containing single-chain variable fragment (scFv) appended to immunoglobulins G offer unique development challenges. Here, we describe the stability of a novel bispecific format, BiS5, where the scFv is tethered to the CH3 domain. BiS5 showed an improved conformational and chemical stability compared with that of BiS4 in which the scFv is appended in the hinge region between the Fab and Fc. By switching the location of the scFv from hinge region to the CH3, there was an improved stabilization of CH2 and scFv domains. Interestingly, no noticeable impact was observed on the conformational stability of CH3 and Fab domains. BiS4 and BiS5 showed different aggregation and fragmentation rates under accelerated temperature stress conditions. BiS4 showed higher fragmentation rates compared with BiS5 likely owing to fragmentation in the linker region on either side of the scFv while BiS5 is more resistant toward fragmentation owing to tethering of scFv to the CH3 domain at its N and C terminus. In conclusion, the location of scFv affects both aggregation and fragmentation kinetics. These insights into the molecular structure and correlations with their physical and chemical stability will help formulation development of these novel bispecific antibodies.

Isolated leptomeningeal progression from sinonasal carcinomas: Implications for staging workup and treatment.

PURPOSE: To evaluate the rate and risk factors of isolated leptomeningeal progression in sinonasal carcinomas. METHODS: We retrospectively reviewed imaging and clinical records to determine progression patterns, and estimated rates using the Kaplan-Meier method. We evaluated risk factors using proportional hazard regression. RESULTS: We analyzed 120 patients who received adjuvant or primary radiotherapy for sinonasal carcinomas. Most patients had T4 disease (68%) and underwent surgery (84%) and chemotherapy (72%). Twenty-seven (23%) patients developed distant metastases (DM), including 20 (17%) with isolated DMs. Leptomeningeal progression was the most common site of isolated DMs (n = 9; 45%) with an average disease-free interval of 1.2 years (0.1-4.3 years). High-grade histology (P = 0.0003), intracranial invasion (P < 0.0001), and neuroendocrine histology (P = 0.06) were associated with increased risk. CONCLUSIONS: Isolated leptomeningeal progression is a common pattern of DM in advanced sinonasal carcinomas. We recommend adding cerebrospinal fluid cytology and contrast-enhanced spine MRI to routine staging evaluations for high-risk patients.

Perioperative management in endoscopic endonasal skull-base surgery: a survey of the North American Skull Base Society.

BACKGROUND: The objective of this work was to better understand variations in perioperative management in endoscopic endonasal skull-base surgery (EESBS) and to identify trends in management based upon the practice patterns of North American Skull Base Society (NASBS) members. METHODS: A 29-question survey evaluating perioperative EESBS management was sent to all NASBS members. Responses were analyzed with descriptive statistics. Subgroup analysis was performed based on participant demographics. A Bonferroni correction was performed and a p value <0.01 was considered statistically significant for subgroup analysis. RESULTS: Of 651 invitees, 116 responded (17.8%). Participants were primarily from the United States (81.0%), and practiced in academic centers (83.6%). The majority were neurosurgeons (55.2%) or rhinologists (27.6%). Most surgeons (83.6%) advocated use of preoperative intravenous antibiotics (96.6%) and image guidance in all cases (83.6%). Lumbar drains were not recommended for cases in which an intraoperative cerebrospinal fluid (CSF) leak was not anticipated (94.8%). Nasoseptal flaps (NSFs) were not recommended in cases without intraoperative CSF leak (84.5%), but were recommended in cases of high-flow intraoperative CSF leak (97.4%). While postoperative restrictions were highly variable, most providers recommended CSF leak precautions (89.7%), flying restrictions (94.0%), and driving restrictions (95.6%) regardless of intraoperative CSF leak status. Most experts also recommended that continuous positive airway pressure (CPAP) be avoided for at least 2 weeks when an intraoperative CSF leak is encountered (81.9%). CONCLUSION: Despite variation in perioperative management of EESBS patients, important trends were identified by this study. Further investigation is needed to standardize perioperative practice patterns in EESBS.

Application of Ultrasonic Aspirators in Rhinology and Skull Base Surgery.

Ultrasonic aspirators (UAs) are increasingly being used in rhinology and skull base surgery. The use of ultrasonic vibration for the removal of bony tissue transfers minimal heat to surrounding tissues and is relatively atraumatic to nearby soft tissue structures. This article details the development and application of this technology in septoturbinoplasty, endoscopic dacryocystorhinostomy (DCR), and skull base surgery. The benefits and limitations of UAs compared with conventionally powered instruments are discussed.

Surgical repair of spontaneous cerebrospinal fluid (CSF) leaks: A systematic review.

Objectives: To review the safety and efficacy of surgical management for spontaneous cerebrospinal fluid (CSF) leaks of the anterior and lateral skull base. Data Sources: A systematic review of English articles using MEDLINE. Review Methods: Search terms included spontaneous, CSF, cerebrospinal fluid, endoscopic, middle fossa, transmastoid, leak, rhinorrhea. Independent extraction of articles by 3 authors. Results: Patients with spontaneous CSF leaks are often obese (average BMI of 38 kg/m2) and female (72%). Many patients also have obstructive sleep apnea (∼45%) and many have elevated intracranial pressure when measured by lumbar puncture. In addition to thinning of the skull base, radiographic studies also demonstrate cortical bone thinning. Endoscopic surgical repair of anterior skull base leaks and middle cranial fossa (MCF) approach for repair of lateral skull base leaks are safe and effective with an average short-term failure rate of 9% and 6.5%, respectively. Long-term failure rates are low. One randomized trial failed to show improved success of anterior leak repairs with the use of a lumbar drain (LD) (95% with vs. 92% without; P = 0.2). In a large retrospective cohort of MCF lateral skull base repairs, perioperative LD use was not necessary in >94% of patients. Conclusions: Spontaneous CSF leaks are associated with female gender, obesity, increased intracranial hypertension, and obstructive sleep apnea. Endoscopic repair of anterior skull base leaks and MCF or transmastoid approaches for lateral skull base leaks have a high success rate of repair. In most cases, intraoperative placement of lumbar drain did not appear to result in improved success rates for either anterior or lateral skull base leaks. Level of Evidence: 2a, Systematic Review.

Aspiration of Aluminum Beverage Can Tab: Case Report and Literature Review.

We describe the case of a 16-year-old male who aspirated a beverage can tab resulting in significant functional impairment. Since the introduction of beverage can opening tabs ("pop-tops" or "pull-tabs") nearly 50 years ago, five cases of their aspiration have been reported in the literature and this is the first case to report tracheal lodgment. We describe the clinical course for this patient including the inadequacy of radiographic evaluation and a significant delay in diagnosis. We highlight unique features of small aluminum foreign bodies that require consideration and mention a potential change in epidemiology associated with evolving product design. Our primary objective is increased awareness among otolaryngologists that radiography is unreliable for diagnosis or localization of small aluminum foreign bodies. The patient history must therefore be incorporated with other imaging modalities and/or endoscopic evaluation. Also, given the marked prevalence of aluminum beverage cans, we suspect that the inadvertent aspiration of can tabs is more common than indicated by the paucity of published reports.

Advances in Microdebrider Technology: Improving Functionality and Expanding Utility.

Since its application in nasal surgery, the microdebrider has revolutionized the practice of endoscopic sinus surgery. As the demands and breadth of procedures performed endoscopically have increased, so has the need for improvement in the microdebrider and related technologies. This article addresses how use of the microdebrider has impacted endonasal surgery and discusses current advances, which include creation of specialty hand pieces and blades, increases in instrument rotational speed, incorporation of navigation and energy, adaptation for intracranial use, and disposable instrumentation designed for in office use. Advances in microdebrider technology have improved functionality and expanded the utility of these devices.