Long-term olfactory loss post-COVID-19: Pathobiology and potential therapeutic strategies.

An acute loss of smell emerged as a striking symptom present in roughly half of the people infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus in the early phases of the COVID-19 pandemic. In most COVID-19 patients, olfaction recovers over the course of a few weeks. However, a lasting partial or complete loss of smell, often associated with distorted olfactory perceptions termed parosmia, has emerged as a widespread problem impacting at least 5%-10% of those who experience anosmia due to COVID-19. Our inability to offer effective therapies to this hyposmic or anosmic population, comprising millions of patients, highlights an enormous unmet need for the medical system. Here, we summarize the current understanding of the pathobiology causing acute olfactory loss due to SARS-CoV-2 infection, focusing on how the virus interacts with the peripheral olfactory system, a major site of viral infection. We also explore the problem of long-COVID olfactory dysfunction, which may accompany other persistent systemic disorders collectively termed postacute sequelae of COVID-19. Specifically, we discuss an emerging model focused on unresolved immune cell activity driving ongoing dysfunction. Finally, we review current and future therapeutic approaches aimed at restoring olfactory function.

Olfactory neuroblastoma mimics molecular heterogeneity and lineage trajectories of small-cell lung cancer.

The olfactory epithelium undergoes neuronal regeneration from basal stem cells and is susceptible to olfactory neuroblastoma (ONB), a rare tumor of unclear origins. Employing alterations in Rb1/Trp53/Myc (RPM), we establish a genetically engineered mouse model of high-grade metastatic ONB exhibiting a NEUROD1+ immature neuronal phenotype. We demonstrate that globose basal cells (GBCs) are a permissive cell of origin for ONB and that ONBs exhibit cell fate heterogeneity that mimics normal GBC developmental trajectories. ASCL1 loss in RPM ONB leads to emergence of non-neuronal histopathologies, including a POU2F3+ microvillar-like state. Similar to small-cell lung cancer (SCLC), mouse and human ONBs exhibit mutually exclusive NEUROD1 and POU2F3-like states, an immune-cold tumor microenvironment, intratumoral cell fate heterogeneity comprising neuronal and non-neuronal lineages, and cell fate plasticity-evidenced by barcode-based lineage tracing and single-cell transcriptomics. Collectively, our findings highlight conserved similarities between ONB and neuroendocrine tumors with significant implications for ONB classification and treatment.

Safety and Feasibility of Steroid-Eluting Stent as a Bolster in Endoscopic Anterior Skull Base Reconstruction.

BACKGROUND: With a rising incidence of cerebrospinal fluid (CSF) leaks, endoscopic endonasal CSF leak repair is increasingly performed. Current approaches utilize a variety of materials including free mucosal grafts and vascularized flaps, but post-op leaks continue to be reported. Steroid-eluting bioabsorbable stents (SES) are used during functional endoscopic sinus surgery for chronic rhinosinusitis to reduce inflammation and scarring while maintaining patency of sinus ostia. OBJECTIVE: The aim of this study is to assess the feasibility of SES as a graft/flap bolster for endoscopic endonasal CSF leak repair. METHODS: This is a retrospective review of patients undergoing endoscopic endonasal CSF leak repair with SES placed as part of the bolster technique at a tertiary care center between January 2019 and May 2022. Age, sex, BMI, comorbid idiopathic intracranial hypertension, pathology, location of CSF leak, intraoperative CSF leak flow, reconstruction type, and presence of post-op CSF leak were recorded. RESULTS: Twelve patients (mean age 52, median BMI 30.9, 58% female) had SES placement as part of the bolster technique. The most common pathology was meningoencephalocele (75%). Reconstruction was performed with either a free mucosal graft (6), or a flap (6). No post-op CSF leaks occurred at a reconstruction site with a stent, and no known complications were reported. All sinusotomies were patent at the last follow-up visit. CONCLUSIONS: SES placement as an adjunct to graft and/or flap bolster appears to be safe and feasible during anterior skull base reconstruction and CSF leak repair providing longer term structural support and preserving sinus drainage patency.

Polycomb repressive complex 2 regulates basal cell fate during adult olfactory neurogenesis.

Adult neurogenesis occurs in the mammalian olfactory epithelium to maintain populations of neurons that are vulnerable to injury yet essential for olfaction. Multipotent olfactory basal stem cells are activated by damage, although mechanisms regulating lineage decisions are not understood. Using mouse lesion models, we focused on defining the role of Polycomb repressive complexes (PRCs) in olfactory neurogenesis. PRC2 has a well-established role in developing tissues, orchestrating transcriptional programs via chromatin modification. PRC2 proteins are expressed in olfactory globose basal cells (GBCs) and nascent neurons. Conditional PRC2 loss perturbs lesion-induced neuron production, accompanied by altered histone modifications and misexpression of lineage-specific transcription factors in GBCs. De-repression of Sox9 in PRC2-mutant GBCs is accompanied by increased Bowman's gland production, defining an unrecognized role for PRC2 in regulating gland versus neuron cell fate. Our findings support a model for PRC2-dependent mechanisms promoting sensory neuronal differentiation in an adult neurogenic niche.

Preparation of Human Olfactory Epithelial Biopsies for Downstream Analysis.

The olfactory mucosa, lining a portion of the nasal cavity, houses the primary olfactory sensory neurons responsible for odor transduction, along with supporting cell populations. Tremendous advances have come from studying the peripheral olfactory system in animal models, especially the mouse. However, acquired human olfactory disorders lack effective therapies, and many of these conditions involve pathology in the olfactory mucosa. Thus, the ability to obtain human olfactory biopsy samples from subjects with olfactory dysfunction, or controls, may be of value. Here, we describe established techniques for collecting olfactory tissue from human subjects and preparing samples for downstream assays such as immunohistochemistry, flow cytometry, single-cell RNA-sequencing, or chromatin studies.

Deconstructing Olfactory Epithelium Developmental Pathways in Olfactory Neuroblastoma.

Olfactory neuroblastoma is a rare tumor arising from the olfactory cleft region of the nasal cavity. Because of the low incidence of this tumor, as well as an absence of established cell lines and murine models, understanding the mechanisms driving olfactory neuroblastoma pathobiology has been challenging. Here, we sought to apply advances from research on the human olfactory epithelial neurogenic niche, along with new biocomputational approaches, to better understand the cellular and molecular factors in low- and high-grade olfactory neuroblastoma and how specific transcriptomic markers may predict prognosis. We analyzed a total of 19 olfactory neuroblastoma samples with available bulk RNA-sequencing and survival data, along with 10 samples from normal olfactory epithelium. A bulk RNA-sequencing deconvolution model identified a significant increase in globose basal cell (GBC) and CD8 T-cell identities in high-grade tumors (GBC from ∼0% to 8%, CD8 T cell from 0.7% to 2.2%), and significant decreases in mature neuronal, Bowman's gland, and olfactory ensheathing programs, in high-grade tumors (mature neuronal from 3.7% to ∼0%, Bowman's gland from 18.6% to 10.5%, olfactory ensheathing from 3.4% to 1.1%). Trajectory analysis identified potential regulatory pathways in proliferative olfactory neuroblastoma cells, including PRC2, which was validated by immunofluorescence staining. Survival analysis guided by gene expression in bulk RNA-sequencing data identified favorable prognostic markers such as SOX9, S100B, and PLP1 expression. Significance: Our analyses provide a basis for additional research on olfactory neuroblastoma management, as well as identification of potential new prognostic markers.

Characterizing Olfactory Dysfunction in Patients with Unilateral Cleft Lip Nasal Deformities.

Background: Unilateral cleft lip nasal deformity (uCLND) is associated with olfactory dysfunction, but the underlying etiology remains poorly understood. Objective: To investigate the etiology of uCLND-associated olfactory dysfunction using clinical, computational, and histologic assessments. Methods: Inclusion criteria: uCLND patients >16 years undergoing septorhinoplasty. Exclusion criteria: prior septoplasty or rhinoplasty, pregnancy, sinusitis. Measured outcomes: patient-reported scores, rhinomanometry, smell identification and threshold tests, computational fluid dynamics (CFD) airflow simulations, and histologic analysis of olfactory epithelium. Results: Five uCLND subjects were included: 18-23 years, three male and two female, four left-sided cleft and one right-sided cleft. All subjects reported moderate to severe nasal obstruction. Smell identification and threshold tests showed varying degrees of hyposmia. Nasal resistance was higher on the cleft side versus noncleft side measured by rhinomanometry (median 3.85 Pa-s/mL, interquartile range [IQR] = 21.96, versus 0.90 Pa-s/mL, IQR = 5.17) and CFD (median 1.04 Pa-s/mL, IQR = 0.94 vs. 0.11 Pa-s/mL, IQR = 0.12). Unilateral olfaction varied widely and was dependent on unilateral percentage olfactory airflow. Biopsies revealed intact olfactory neuroepithelium. Conclusions: uCLND-associated olfactory dysfunction appears to be primarily conductive in etiology and highly susceptible to variations in nasal anatomy. Clinical Trial Registration number: NCT04150783.

Persistent post-COVID-19 smell loss is associated with immune cell infiltration and altered gene expression in olfactory epithelium.

SARS-CoV-2 causes profound changes in the sense of smell, including total smell loss. Although these alterations are often transient, many patients with COVID-19 exhibit olfactory dysfunction that lasts months to years. Although animal and human autopsy studies have suggested mechanisms driving acute anosmia, it remains unclear how SARS-CoV-2 causes persistent smell loss in a subset of patients. To address this question, we analyzed olfactory epithelial samples collected from 24 biopsies, including from nine patients with objectively quantified long-term smell loss after COVID-19. This biopsy-based approach revealed a diffuse infiltrate of T cells expressing interferon-γ and a shift in myeloid cell population composition, including enrichment of CD207+ dendritic cells and depletion of anti-inflammatory M2 macrophages. Despite the absence of detectable SARS-CoV-2 RNA or protein, gene expression in the barrier supporting cells of the olfactory epithelium, termed sustentacular cells, appeared to reflect a response to ongoing inflammatory signaling, which was accompanied by a reduction in the number of olfactory sensory neurons relative to olfactory epithelial sustentacular cells. These findings indicate that T cell-mediated inflammation persists in the olfactory epithelium long after SARS-CoV-2 has been eliminated from the tissue, suggesting a mechanism for long-term post-COVID-19 smell loss.

Olfactory dysfunction and COVID-19.

Here, we provide an overview of olfactory dysfunction associated with COVID-19. We provide background regarding the organization and function of the peripheral olfactory system. A review of the relevant literature on anosmia and parosmia due to infection with SARS-CoV-2, the virus causing COVID-19, is provided. Specific attention is focused on possible mechanisms by which the virus may interact with and damage the cell populations of peripheral olfactory system. Evidence from human studies as well as animal models is considered. Finally, we discuss current recommendations for evaluation and management of patients with persistent post-COVID olfactory dysfunction, as well as possible future research directions.

Persistent post-COVID-19 smell loss is associated with inflammatory infiltration and altered olfactory epithelial gene expression.

Most human subjects infected by SARS-CoV-2 report an acute alteration in their sense of smell, and more than 25% of COVID patients report lasting olfactory dysfunction. While animal studies and human autopsy tissues have suggested mechanisms underlying acute loss of smell, the pathophysiology that underlies persistent smell loss remains unclear. Here we combine objective measurements of smell loss in patients suffering from post-acute sequelae of SARS-CoV-2 infection (PASC) with single cell sequencing and histology of the olfactory epithelium (OE). This approach reveals that the OE of patients with persistent smell loss harbors a diffuse infiltrate of T cells expressing interferon-gamma; gene expression in sustentacular cells appears to reflect a response to inflammatory signaling, which is accompanied by a reduction in the number of olfactory sensory neurons relative to support cells. These data identify a persistent epithelial inflammatory process associated with PASC, and suggests mechanisms through which this T cell-mediated inflammation alters the sense of smell.

Validation of the Argentine version of the Montreal Cognitive Assessment Test (MOCA): A screening tool for Mild Cognitive Impairment and Mild Dementia in Elderly.

The MoCA is a brief useful test to diagnose mild cognitive impairment (MCI) and mild dementia (MD). To date, no Argentine cross-cultural adapted validations of the Spanish version have been reported. OBJECTIVE: To validate the MoCA in the elderly and study its usefulness in MCI and MD. METHODS: This study included 399 individuals over 60 years old evaluated in the Cognitive-Behavioral Department (2017-2018). Patients with<3 years of education, sensory disturbances, psychiatric disorders, or moderate-severe dementia were excluded. The control group comprised cognitively normal subjects. Participants were classified according to neuropsychological assessment and clinical standard criteria into Control, MCI or MD groups. A locally adapted MoCA (MOCA-A) was administered to the patients and controls. RESULTS: Mean educational level was 10.34 years (SD 3.5 years). MoCA-A score differed significantly among groups (p<0.0001). MoCA-A performance correlated with educational level (r: 0.406 p<0.00001). Adopting a cut-off score ≥25 (YI=0.55), the sensitivity for MCI was 84.8% and for MD ​​100%, with specificity of 69.7%. When adding a single point to the score in patients with ≤12 years of education, the specificity of the test reached 81%. CONCLUSION: The MoCA-A is an accurate reliable screening test for MCI and MD in Argentina.

O MoCA é um teste breve e útil para diagnosticar comprometimento cognitivo leve (CCL) e demência leve. Até o momento, nenhuma validação argentina com adaptação transcultural da versão em espanhol havia sido relatada. OBJETIVO: Validar o MoCA em idosos e estudar sua utilidade no CCL e demência leve. MÉTODOS: Este estudo incluiu 399 indivíduos acima de 60 anos avaliados no departamento cognitivo-comportamental (2017-2018). Foram excluídos pacientes com menos de 3 anos de escolaridade, com distúrbios sensoriais, distúrbios psiquiátricos e demência moderada a grave. O grupo controle foi cognitivamente normal. Eles foram classificados de acordo com a avaliação neuropsicológica e os critérios clínicos padrão em Controles, MCI e demência leve. A versão adaptada do MoCA (MOCA-A) foi administrado aos pacientes e controles. RESULTADOS: Média de escolaridade: 10,34 anos (DP: 3,5). O escore MoCA-A foi significativamente diferente entre os grupos (p<0,0001). O MoCA-A correlacionou-se com a escolaridade (r=0,406 p<0,00001). Com uma pontuação de corte ≥25 (IY=0,55), a sensibilidade para CCL foi de 84,8% e para demência leve 100%, com especificidade de 69,7%. Adicionando um ponto único à pontuação em pacientes com menos de 12 anos de escolaridade, a especificidade do teste atingiu 81%. CONCLUSÃO: O MoCA-A é um teste de rastreamento preciso e confiável para MCI e demência leve na Argentina.

Validation of the Argentine version of the Montreal Cognitive Assessment Test (MOCA): A screening tool for Mild Cognitive Impairment and Mild Dementia in Elderly / Validação da versão argentina do teste montreal cognitive assessment test (moca): um instrumento de triagem para comprometimento cognitivo leve e demência leve em idosos

ABSTRACT. The MoCA is a brief useful test to diagnose mild cognitive impairment (MCI) and mild dementia (MD). To date, no Argentine cross-cultural adapted validations of the Spanish version have been reported. Objective: To validate the MoCA in the elderly and study its usefulness in MCI and MD. Methods: This study included 399 individuals over 60 years old evaluated in the Cognitive-Behavioral Department (2017-2018). Patients with<3 years of education, sensory disturbances, psychiatric disorders, or moderate-severe dementia were excluded. The control group comprised cognitively normal subjects. Participants were classified according to neuropsychological assessment and clinical standard criteria into Control, MCI or MD groups. A locally adapted MoCA (MOCA-A) was administered to the patients and controls. Results: Mean educational level was 10.34 years (SD 3.5 years). MoCA-A score differed significantly among groups (p<0.0001). MoCA-A performance correlated with educational level (r: 0.406 p<0.00001). Adopting a cut-off score ≥25 (YI=0.55), the sensitivity for MCI was 84.8% and for MD ​​100%, with specificity of 69.7%. When adding a single point to the score in patients with ≤12 years of education, the specificity of the test reached 81%. Conclusion: The MoCA-A is an accurate reliable screening test for MCI and MD in Argentina.

RESUMO. O MoCA é um teste breve e útil para diagnosticar comprometimento cognitivo leve (CCL) e demência leve. Até o momento, nenhuma validação argentina com adaptação transcultural da versão em espanhol havia sido relatada. Objetivo: Validar o MoCA em idosos e estudar sua utilidade no CCL e demência leve. Métodos: Este estudo incluiu 399 indivíduos acima de 60 anos avaliados no departamento cognitivo-comportamental (2017-2018). Foram excluídos pacientes com menos de 3 anos de escolaridade, com distúrbios sensoriais, distúrbios psiquiátricos e demência moderada a grave. O grupo controle foi cognitivamente normal. Eles foram classificados de acordo com a avaliação neuropsicológica e os critérios clínicos padrão em Controles, MCI e demência leve. A versão adaptada do MoCA (MOCA-A) foi administrado aos pacientes e controles. Resultados: Média de escolaridade: 10,34 anos (DP: 3,5). O escore MoCA-A foi significativamente diferente entre os grupos (p<0,0001). O MoCA-A correlacionou-se com a escolaridade (r=0,406 p<0,00001). Com uma pontuação de corte ≥25 (IY=0,55), a sensibilidade para CCL foi de 84,8% e para demência leve 100%, com especificidade de 69,7%. Adicionando um ponto único à pontuação em pacientes com menos de 12 anos de escolaridade, a especificidade do teste atingiu 81%. Conclusão: O MoCA-A é um teste de rastreamento preciso e confiável para MCI e demência leve na Argentina.

Elevated glucose alters global gene expression and tenascin-C alternative splicing in mesangial cells.

Mesangial cells are the major extracellular matrix (ECM)-producing cells in the kidney glomerulus and, when exposed to elevated glucose levels, they up-regulate assembly of fibronectin (FN) and other ECM proteins. Increases in glucose concentration are known to alter gene expression; here we investigated the connection between increased ECM production and changes in gene expression in mesangial cells. Comparison of mesangial cells grown in normal or high glucose conditions by RNA-sequencing showed significant expression changes in over 6000 genes and, when grouped by KEGG pathway analysis, identified the ECM-receptor interaction and focal adhesion pathways among the top 5 upregulated pathways. Of note was the significant increase in expression of tenascin-C (TN-C), a known regulator of FN matrix assembly. Mouse TN-C has multiple isoforms due to alternative splicing of 6 FNIII repeat exons. In addition to the transcriptional increase with high glucose, exon inclusion via alternative splicing was also changed resulting in production of higher molecular weight isoforms of TN-C. Mesangial cells grown in normal glucose secreted small isoforms with 1-2 variable repeats included whereas in high glucose large isoforms estimated to include 5 repeats were secreted. Unlike the smaller isoforms, the larger TN-C was not detected in the FN matrix. This change in TN-C isoforms may affect the regulation of FN matrix assembly and in this way may contribute to increased ECM accumulation under high glucose conditions.

Acute Bilateral Superior Branch Vestibular Neuropathy.

The rapid onset of a bilateral vestibular hypofunction (BVH) is often attributed to vestibular ototoxicity. However, without any prior exposure to ototoxins, the idiopathic form of BVH is most common. Although sequential bilateral vestibular neuritis (VN) is described as a cause of BVH, clinical evidence for simultaneous and acute onset bilateral VN is unknown. We describe a patient with an acute onset of severe gait ataxia and oscillopsia with features compatible with acute BVH putatively due to a bilateral VN, which we serially evaluated with clinical and laboratory vestibular function testing over the course of 1 year. Initially, bilateral superior and horizontal semicircular canals and bilateral utricles were impaired, consistent with damage to both superior branches of each vestibular nerve. Hearing was spared. Only modest results were obtained following 6 months of vestibular rehabilitation. At a 1-year follow-up, only the utricular function of one side recovered. This case is the first evidence supporting an acute presentation of bilateral VN as a cause for BVH, which would not have been observed without critical assessment of each of the 10 vestibular end organs.

Establishing Primary Human Glioblastoma Adherent Cultures from Operative Specimens.

This chapter describes a method for isolation, maintenance, and propagation of primary glioblastoma (GBM) cells in adherent monolayer cultures from patient tumor specimens. This method enables the establishment of GBM cultures with stem or progenitor-like cell characteristics, including self-renewal capacity, differentiation along restricted neural lineages, and tumor-initiating potential when orthotopically injected into immunocompromised mice. This experimentally tractable model system is therefore suitable for a wide variety of analyses in vitro as well as in vivo. Key examples of biological analyses that can be performed using these cells are also described.

Intra-Attack Vestibuloocular Reflex Changes in Ménière's Disease.

Ménière's attack has been shown to temporarily alter the vestibuloocular reflex (VOR). A patient with unilateral Ménière's disease was serially evaluated with the video Head Impulse Test during single, untreated episodes of acute vertigo. Spontaneous nystagmus activity was concurrently recorded in order to establish the three typical phases of Ménière's attack (irritative, paralytic, and recovery) and correlate them with VOR performance. The onset of attack was associated with a quick change in VOR gain on the side of the affected ear. While a rapidly progressive reduction of the VOR was evident at the paralytic nystagmus phase, in the recovery phase the VOR gain returned to normal and the direction of the previous nystagmus reversed. The membrane rupture potassium intoxication theory provides a good foundation with which to explain these dynamic VOR changes and the observed triphasic direction behavior of the spontaneous nystagmus. We additionally postulated that endolymphatic fluid displacement could have a synergic effect during the earliest phase of attack.

Overall outpatient satisfaction and its components: perceived changes at the Huntington VA Medical Center over five years.

The number of veterans obtaining healthcare services at Huntington Veteran's Administration Medical Center (HVAMC) had significantly increased over the five-year span from fiscal year 2000 through fiscal year 2004. The authors' purpose in this study was to determine changes in outpatient satisfaction levels at HVAMC over that five-year period. The authors assessed the following specific measures of patient satisfaction: courtesy, access, patient preferences, coordination of care, education and information, emotional support, overall quality, pharmacy services, and overall satisfaction. Of the 17,000 patients meeting the criteria, 630 were randomly selected; 195 patients completed surveys, resulting in a 31% response rate. Results demonstrated an overall significantly higher level of patient satisfaction than five years previously. On the basis of these results, the medical center administration can probably conclude that any process he improvements made over the five-year period have been successful.