Anosmia: Differential diagnosis, evaluation, and management

Advanced investigation of a putative adsorption process of nine non key food odorants (non-KFOs) on the broadly tuned human olfactory receptor OR2W1: Statistical physics modeling and molecular docking study

In the present paper, statistical physics formalism was used to understand the olfactory perception via the investigation of dose-olfactory response curves of a putative adsorption process of nine non key food odorants (non-KFOs) on the broadly tuned human olfactory receptor OR2W1, in order to quantitative characterize the interactions between the nine studied non-KFOs, i. e., furfuryl sulfide, furfuryl disulfide, benzyl methyl disulfide, furfuryl methyl disulfide, benzyl methyl sulfide, 1-phenylethanethiol, benzyl mercaptan, furfuryl methyl sulfide and 3-phenylpropanol molecules and OR2W1 binding sites at a molecular level. Two advanced adsorption models have been proposed: the advanced monolayer monoenergy model (monolayer model with identical and independent olfactory receptor binding sites) (Model 1) and the advanced monolayer model with two independent types of olfactory receptor binding sites (Model 2). It was concluded that the monolayer monoenergy model was selected as the most adequate model to fit the experimental dose-olfactory response curves tabulated in literature. Actually, the numerical values of the three fitted physico-chemical parameters (RM1, n and C1) were obtained by a non-linear regression. Indeed, modeling results suggested that the number of docked non-KFOs per OR2W1 binding site n values (1.24 < n < 1.94) was always superior to 1, which indicated the non-parallel orientation of the studied odorants on the olfactory receptor and the multi-molecular adsorption mechanism. The estimated molar adsorption energy ΔEa values (ranged from 6.07 to 12.16 kJ/mol) for the nine olfactory systems confirmed the physical the exothermic characters of the adsorption process since ΔEa values were lower than 40 kJ/mol and positive. Furthermore, these estimated parameters were applied to characterize stereographically and energetically the interaction between the nine non-KFOs and OR2W1 through the determination of the human receptor binding site size distributions (RSDs) and the adsorption energy distributions (AEDs), which were spread out from 0.25 to 6.50 nm and from 0 to 22.50 kJ/mol, respectively. The docking computation between these nine non-KFOs and OR2W1 proved that the estimated binding affinities were belonged to the adsorption energies spectrum in general and the specific adsorption energy band or the molecular vibration modes limited spectrum (between 2.50 kJ/mol and 17 kJ/mol) (approximate olfactory band).

Decreased frontal and orbital volumes and increased cerebellar volumes in patients with anosmia Of Unknown origin: A subtle connection?

PURPOSE

Neuroimaging studies have shown that anosmia is accompanied by a decreased olfactory bulb volume, yet little is known about alterations in cerebral and cerebellar lobule volumes. The purpose of this study was to investigate structural brain alterations in anosmic patients.

METHODS

Sixteen anosmic patients (mean age 42.62 ± 16.57 years; 6 women and 10 men) and 16 healthy controls (mean age 43.37 ± 18.98 years; 9 women and 7 men) were included in this retrospective study. All subjects who underwent magnetic resonance imaging scans were analyzed using VolBrain and voxel-based morphometry after olfactory testing.

RESULTS

Despite being statistically insignificant, analysis using VBM revealed greater gray matter (GM) and white matter in the anosmia group compared to the healthy subjects. However, decreased GM (p < 0.001) and increased cerebellar (p = 0.046) volumes were observed in the anosmic patients.

CONCLUSIONS

The study revealed structural brain alterations in specific areas beyond the olfactory bulb. Our results indicate that the cerebellum may play an exceptional role in the olfactory process and that this will be worth evaluating with further dynamic neuroimaging studies.

Comparison between olfactory training and curcumin therapy in improving olfactory dysfunction in patients with chronic kidney disease

Objective

Olfactory dysfunction can be seen in chronic kidney disease (CKD) patients. We aimed to investigate the effects of olfactory training and curcumin on olfactory dysfunction in CKD patients and compare their impact with a placebo.

Methods

We conducted a double-blind, randomized, placebo-controlled trial in CKD patients, 2021-2022. We enrolled 60 participants in our study into three groups (curcumin, training, and control). Participants were randomized into trials and control groups and assessed using the Iran-smell identification test (Iran-SIT), a questionnaire of olfactory disorders (QOD), and a self-assessment tool. P-value < 0.05 was considered statistically significant.

Results

We gathered 58 participants (mean age of 56.1 ± 2.5, 56.9% men). All the tests showed that curcumin improved olfactory function after the trial, though it was significant in QOD (17.5 ± 11.8 vs. 13.1 ± 9.7, p = 0.045) and self-assessment results (8.5 ± 3.1 vs. 9.5 ± 4.0, p = 0.047). Moreover, compared to baseline, training patients experienced an increase in their olfactory function in Iran-SIT (15.3 ± 4.9 vs. 18.8 ± 2.7, p = 0.001), QOD (19.0 ± 10.4 vs. 12.2 ± 9.9, p = 0.003), and self-assessment tools (6.8 ± 1.8 vs. 8.2 ± 3.1, p = 0.027). In contrast, the olfactory function was unchanged in control in all the tests (p > 0.05). Also, the improved change of Iran-SIT and QOD scores during the trial was more significant in training compared to the curcumin group (p < 0.002).

Conclusion

The findings of this study indicate that olfactory training, even more than curcumin, can improve olfactory function in CKD patients. This information may help manage olfactory dysfunction in the CKD population.

Food Intake Changes and Their Impact on Quality of Life in Spanish Citizens with and without COVID-19 during Lockdown

The pervasive impact of the COVID-19 pandemic is just beginning to be analyzed. To date, only a handful of these studies have investigated the relationship between an individual’s quality of life (QoL) and their changes in food intake due to the virus (from the associated symptomatology of diagnosis to the universal impact of lockdown on individual lives, regardless of a person’s health status). Therefore, the purpose of this study is to identify changes in food intake resulting from the pandemic and the corresponding impact on QoL in the Spanish population. This study focuses its investigation on the 3-month time period within which lockdown was its most restrictive, March−May 2020. Survey questions ask participants to compare their eating habits, general health status, and QoL during these 3 months to times prior to the pandemic. We conducted an online survey amongst the Spanish population over 18 years old. Three surveys were administered: (1) the adult eating behavior questionnaire (EABQ), (2) EuroQoL-5D-5L, and (3) The determinants lifestyle changes during lockdown period (March to May 2020). A total of 86 participants were included, with a mean age of 34 years. In the analysis of QoL, significant differences were found according to age, sex, and the presence of a COVID-19 diagnosis. Likewise, in the analysis of food intake, significant differences were found by age (greater changes in the 18−29-years-old population) (p< 0.01) and by sex (women p < 0.03), as well as greater changes in those with a diagnosis of COVID-19. Furthermore, both food intake and COVID-19 diagnosis were variables that predicted QoL outcomes. In sum, forced home lockdown can cause changes in food intake, which can predict a lower QoL. It follows that the lockdown situation caused by the worldwide COVID-19 pandemic has affected the food intake and overall QoL of the Spanish population.

Effects of Social Isolation Measures Caused by the COVID-19 Pandemic on Occupational Balance, Participation, and Activities' Satisfaction in the Spanish Population

The COVID-19 pandemic caused a lot of social and health chaos. Our main aim in this study was to examine the impact of the COVID-19 pandemic on occupational balance in the Spanish population, one year post the beginning of the pandemic compared with the pre-pandemic period. Data were collected among the Spanish population over 18 years of age by the Occupational Balance Questionnaire online survey; questions about satisfaction and performance of activities, and on the modification of routine and habits were asked. A total of 300 participants were included; 55.3% were female, with a mean age of 41.39 years. Significantly greater occupational imbalance was found in 1-year-post-confinement period of pandemic, as well as an increase in the difficulty of performance and a decrease in satisfaction with it. A greater number of the sample had modified their routines (p < 0.01), lost habits (p < 0.01), and did not resume habits (p < 0.01). In the analysis by age groups, differences were found in the variables related to habits and occupational balance. The social restriction measures negatively impacted occupational balance in the Spanish population. There was a decrease in occupational participation, increased difficulty in performance, decreased satisfaction in occupational performance, and modification of habits and routines.

A comprehensive review on current understanding of bradykinin in COVID-19 and inflammatory diseases

Bradykinin, a member of the kallikrein–kinin system (KKS), is a potent, short-lived vasoactive peptide that acts as a vasodilator and an inflammatory mediator in a number of signaling mechanisms. Bradykinin induced signaling is mediated through kinin B1 (BDKRB1) and B2 (BDKRB2) transmembrane receptors coupled with different subunits of G proteins (G_αi/G_α0, G_αq and G_β1γ2). The bradykinin-mediated signaling mechanism activates excessive pro-inflammatory cytokines, including IL-6, IL-1β, IL-8 and IL-2. Upregulation of these cytokines has implications in a wide range of clinical conditions such as inflammation leading to fibrosis, cardiovascular diseases, and most recently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In SARS-CoV-2 infection, bradykinin is found to be at raised levels and is reported to trigger a diverse array of symptoms. All of this brings bradykinin to the core point as a molecule of immense therapeutic value. Our understanding of its involvement in various pathways has expanded with time. Therefore, there is a need to look at the overall picture that emerges from the developments made by deciphering the bradykinin mediated signaling mechanisms involved in the pathological conditions. It will help devise strategies for developing better treatment modalities in the implicated diseases. This review summarizes the current state of knowledge on bradykinin mediated signaling in the diverse conditions described above, with a marked emphasis on the therapeutic potential of targeting the bradykinin receptor.

“Anosmia” the mysterious collateral damage of COVID-19

COVID-19 pandemic spreads worldwide, with more than 100 million positive cases and more than 2 million deaths. From the beginning of the COVID-19 pandemic, several otolaryngologists described many cases of a sudden loss of smell (anosmia) associated with the disease with or without additional symptoms. Anosmia is often the first and sometimes the only sign in the asymptomatic carriers of COVID-19. Still, this disorder is underestimated, and it is not life-threatening. However, it significantly decreases the quality of life. This olfactory dysfunction continues in several cases even after the nasopharyngeal swab was negative. The occurrence of anosmia can be used as a screening tool for COVID-19 patients and can be used to identify these patients to accomplish the isolation and tracking procedures. In this review, we highlighted the possible mechanisms of anosmia in COVID-19 patients, major pathologies and features of anosmia, implications of anosmia in early diagnosis of COVID-19, evaluation of the smell function during COVID-19, and management and treatment options of COVID-19 anosmia.

Neuropsychological Symptom Identification and Classification in the Hospitalized COVID-19 Patients During the First Wave of the Pandemic in a Front-Line Spanish Tertiary Hospital

Studies specifically designed to determine the profile of psychiatric symptoms among COVID-19 patients are limited and based on case series, self-report questionnaires, and surveys. The objective of the study was to identify and classify the neuropsychological symptoms of hospitalized COVID-19 patients during the first wave of the pandemic in one of the most important front-line tertiary hospitals from Spain, and to analyze its correlation with diagnosed mental disorders, as well as to explore potential risk factors associated with mental health problems. This observational, cohort study involved data from COVID-19 patients at the University Hospital 12 de Octubre (Madrid, Spain) from February to May 2020. First, patients underwent a semistructured phone interview (screening phase), based on the Mini International Neuropsychiatric Interview (MINI). Then the confirmation of the diagnosis (confirmation phase) was performed in patients who reported a mental disorder development or worsening. A factorial analysis was performed to identify groups of symptoms. A tetrachoric matrix was created, and factorial analysis, by a principal component analysis, was employed upon it. Factors showing values >1.0 were selected, and a varimax rotation was applied to these factors. Symptoms most frequently identified in patients were anosmia/ageusia (54.6%), cognitive complaints (50.3%), worry/nervousness (43.8%), slowing down (36.2%), and sadness (35.4%). Four factors were identified after the screening phase. The first ("anxiety/depression") and second ("executive dysfunction") factors explained 45.4 and 11.5% of the variance, respectively. Women, age between 50 and 60 years, duration in the hospital (more than 13 days), and psychiatric history showed significant higher levels (number of symptoms) in the factors. This study reports the factor structure of the psychiatric symptoms developed by patients with a confirmed diagnosis of SARS-CoV2 during the first wave of the COVID-19. Three item domains (anxiety, depression, and posttraumatic stress disorder symptoms) were loaded together on one factor, whereas sleep disturbance stood up as a separate factor. Interestingly, the item anosmia/ageusia was not captured by any factor. In conclusion, an increase in neuropsychiatric morbidity is expected in the upcoming months and years. Therefore, screening for early symptoms is the first step to prevent mental health problems associated with this pandemic.

Clinical Features of Parosmia Associated With COVID-19 Infection

Objective

To characterize the clinical features, risk factors, symptom time‐course, and quality of life implications for parosmia among coronavirus disease (COVID)‐related olfactory dysfunction patients.

Methods

Individuals with olfactory dysfunction associated with laboratory‐confirmed or clinically suspected COVID‐19 infection were recruited from otolaryngology and primary care practices over a period from August 2020 to March 2021. Participants completed olfactory dysfunction and quality of life surveys.

Results

A total of 148 (64.1%) of 231 respondents reported parosmia at some point. Parosmia developed within 1 week of any COVID‐19 symptom onset in 25.4% of respondents, but more than 1 month after symptom onset in 43.4% of respondents. Parosmia was associated with significantly better quantitative olfactory scores on Brief Smell Identification Test (8.7 vs. 7.5, P = .006), but demonstrated worse quality of life scores, including modified brief Questionnaire of Olfactory Dysfunction—Negative Statements and Sino‐Nasal Outcome Test‐22 scores (12.1 vs. 8.5, P < .001; 26.2 vs. 23.2, P = .113). Participants who developed parosmia at any point were significantly younger and less likely to have history of chronic sinusitis than those who did not develop parosmia (40.2 vs. 44.9 years, P = .007; 7.2% vs. 0.7%, P = .006).

Conclusion

COVID‐19‐associated olfactory dysfunction is frequently linked with development of parosmia, which often presents either at onset of smell loss or in a delayed fashion. Despite better quantitative olfactory scores, respondents with parosmia report decreased quality of life. A majority of respondents with persistent parosmia have sought treatment.

Level of Evidence

3 Laryngoscope, 132:633–639, 2022

Prevalence of subjective impairments of the sense of smell and taste in employees of retirement and nursing homes during SARS-CoV-2 pandemic

Aim

To investigate the usability of querying subjective impairments of the sense of smell and taste in order to improve pre‐test probability in testing for SARS‐CoV‐2. To achieve this, exploring the prevalence of these restrictions in the COVID‐19‐negative population, as well as nasal co‐symptoms.

Design

A cross‐sectional study was carried out as part of the secondary prophylaxis, following the STROBE guidelines of the EQUATOR network.

Methods

In total, 1,734 employees of retirement and nursing homes were tested for COVID‐19 and asked for subjective reduction or loss in the sense of smell and taste, furthermore about nasal co‐symptoms such as nasal obstruction and rhinorrhoea.

Results

All employees tested negative for COVID‐19. Subjective hyposmia and hypogeusia rarely occurred and were usually accompanied by other nasal symptoms such as nasal obstruction. Querying subjective hyposmia/anosmia or hypogeusia/ageusia appears to be a useful anamnestic instrument for the clinical assessment of the probability of SARS‐CoV‐2 infection.

The role of sensory and olfactory pathways in multiple chemical sensitivity

Multiple chemical sensitivity (MCS) is characterised by non-specific and recurring symptoms affecting multiple organs and associated with exposure to chemicals, even at low concentrations, which are, under normal circumstances, harmless to the general population. Symptoms include general discomfort, cardiovascular instability, irritation of the sensory organs, breath disorders, hypersensitivity affecting the skin and epithelial lining of the gut, throat and lungs, anxiety, and learning and memory loss. Chemical intolerance is a key distinguishing feature of MCS, limiting considerably patients' lifestyle with serious social, occupational and economic implications. Since no specific diagnostic markers are currently available for chemical intolerance, the diagnosis relies on clinical symptoms. Despite the formulation of several hypotheses regarding the pathophysiology of MCS, its mechanisms remain undefined. A person-centred care approach, based on multidisciplinary and individualised medical plans, has shown promising results. However, more definite treatment strategies are required. We have reviewed the main experimental studies on MCS pathophysiology, focusing on the brain networks involved, the impact of environmental pollution on the olfactory system and the correlation with other pathologies such as neurodegenerative diseases. Finally, we discuss treatment strategies targeting the olfactory system.

Olfactory dysfunction in aging and neurodegenerative diseases

Alterations in olfactory functions are proposed to be early biomarkers for neurodegeneration. Many neurodegenerative diseases are age-related, including two of the most common, Parkinson's disease (PD) and Alzheimer's disease (AD). The establishment of biomarkers that promote early risk identification is critical for the implementation of early treatment to postpone or avert pathological development. Olfactory dysfunction (OD) is seen in 90% of early-stage PD patients and 85% of patients with early-stage AD, which makes it an attractive biomarker for early diagnosis of these diseases. Here, we systematically review widely applied smelling tests available for humans as well as olfaction assessments performed in some animal models and the relationships between OD and normal aging, PD, AD, and other conditions. The utility of OD as a biomarker for neurodegenerative disease diagnosis and future research directions are also discussed.

Pathophysiology and possible treatments for olfactory-gustatory disorders in patients affected by COVID-19

SARS-CoV-2 infects host cells mainly through the interaction between the virus's Spike protein and the viral receptors namely Angiotensin-Converting Enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). Both are highly expressed in the gastrointestinal tract, in the nasal and bronchial epithelium, as well as in the type II alveolar epithelial cells. The aim of this review is to report the evidences from the scientific literature on the pathophysiology and the available treatments for olfactory-gustatory disorders in patients with COVID-19. The mechanisms involved in these disorders are still unclear and studies on specific therapies are scarce. However, it has been hypothesized that a decrease in the sensitivity of the sensory neurons as well as the co-expression of ACE2 and TMPRSS2 in the alveolar epithelial cells are the main causes of olfactory-gustatory disorders. The possible mechanisms described in the literature for changes in taste perception in patients with COVID-19 include olfactory disorders and a competitive activity of COVID-19 on ACE2 receptors in the taste buds. In addition, SARS-CoV-2 can bind to sialic acid receptors in the taste buds. In general, evidences show that there is no specific treatment for olfactory-taste disorders induced by SARS-CoV-2, even though some treatments have been used and have shown some promising results, such as olfactory training, intranasal application of sodium citrate and vitamin A, as well as systemic use of omega-3 and zinc. Corticosteroids have also been used as a pharmacological approach to treat patients with olfactory dysfunction with some contradictory results. The knowledge of the mechanisms by which SARS-CoV-2 influences the sensory systems and how effective therapies can treat the loss of smell and taste will have important implications on the understanding and clinical management of olfactory-taste disorders.

Corticosteroid nasal spray for recovery of smell sensation in COVID-19 patients: A randomized controlled trial

Objectives

To evaluate the role of the topical corticosteroid, mometasone furoate, nasal spray in the treatment of post COVID-19 anosmia.

Methods

A prospective, randomized, controlled trial was conducted among patients with post COVID-19 anosmia. One hundred patients were randomly assigned to two groups; group I included 50 patients received mometasone furoate nasal spray in an appropriate dose of 2 puff (100 μg) once daily in each nostril for 3 weeks with olfactory training, group II included 50 patients were advised to keep on olfactory training only. The assessment of smell was done using (Visual Analog Scale from 0 to 10). All patients were initially evaluated after their recovery from COVID-19 and followed up for 3 weeks. The smell scores were recorded weekly and the duration of smell loss was recorded from the onset of anosmia till the full recovery.

Results

In both groups, the smell scores significantly improved by the end of the third week (P < 0.001). By comparing smell scores between both groups after 1 week, 2 weeks, and 3 weeks of treatment, there were no statistically significant differences between both groups. In group I, (62%) of patients completely recovered their sense of smell after 3 weeks of treatment, compared to (52%) of patients in group II (P = 0.31).

Conclusion

The results suggested that using mometasone furoate nasal spray as a topical corticosteroid in the treatment of post COVID-19 anosmia offers no superiority benefits over the olfactory training, regarding smell scores, duration of anosmia, and recovery rates.

Trial registration

ClinicalTrials.gov ID: NCT04484493

Loss of Olfactory Function-Early Indicator for Covid-19, Other Viral Infections and Neurodegenerative Disorders

The loss of the senses of smell (anosmia) and taste (ageusia) are rather common disorders, affecting up to 20% of the adult population. Yet, this condition has not received the attention it deserves, most probably because per se such a disorder is not life threatening. However, loss of olfactory function significantly reduces the quality of life of the affected patients, leading to dislike in food and insufficient, exaggerated or unbalanced food intake, unintentional exposure to toxins such as household gas, social isolation, depression, and an overall insecurity. Not only is olfactory dysfunction rather prevalent in the healthy population, it is, in many instances, also a correlate or an early indicator of a panoply of diseases. Importantly, olfactory dysfunction is linked to the two most prominent neurodegenerative disorders, Parkinson's disease and Alzheimer's disease. Anosmia and hyposmia (reduced sense of smell) affect a majority of patients years before the onset of cognitive or motor symptoms, establishing olfactory dysfunction as early biomarker that can enable earlier diagnosis and preventative treatments. In the current health crisis caused by SARS-CoV2, anosmia and dysgeusia as early-onset symptoms in virus-positive patients may prove to be highly relevant and crucial for pre-symptomatic Covid-19 detection from a public health perspective, preceding by days the more classical respiratory tract symptoms such as cough, tightness of the chest or fever. Thus, the olfactory system seems to be at the frontline of pathologic assault, be it through pathogens or insults that can lead to or at least associate with neurodegeneration. The aim of this review is to assemble current knowledge from different medical fields that all share a common denominator, olfactory/gustatory dysfunction, and to distill overarching etiologies and disease progression mechanisms.

COVID-19-Related Anosmia: The Olfactory Pathway Hypothesis and Early Intervention

Anosmia is a well-described symptom of Corona Virus Disease 2019 (COVID-19). Several respiratory viruses are able to cause post-viral olfactory dysfunction, suggesting a sensorineural damage. Since the olfactory bulb is considered an immunological organ contributing to prevent the invasion of viruses, it could have a role in host defense. The inflammatory products locally released in COVID-19, leading to a local damage and causing olfactory loss, simultaneously may interfere with the viral spread into the central nervous system. In this context, olfactory receptors could play a role as an alternative way of SARS-CoV-2 entry into cells locally, in the central nervous system, and systemically. Differences in olfactory bulb due to sex and age may contribute to clarify the different susceptibility to infection and understand the role of age in transmission and disease severity. Finally, evaluation of the degree of functional impairment (grading), central/peripheral anosmia (localization), and the temporal course (evolution) may be useful tools to counteract COVID-19.

COVID-19 Is a Multifaceted Challenging Pandemic Which Needs Urgent Public Health Interventions

Until less than two decades ago, all known human coronaviruses (CoV) caused diseases so mild that they did not stimulate further advanced CoV research. In 2002 and following years, the scenario changed dramatically with the advent of the new more pathogenic CoVs, including Severe Acute Respiratory Syndome (SARS-CoV-1), Middle Eastern respiratory syndrome (MERS)-CoV, and the new zoonotic SARS-CoV-2, likely originated from bat species and responsible for the present coronavirus disease (COVID-19), which to date has caused 15,581,007 confirmed cases and 635,173 deaths in 208 countries, including Italy. SARS-CoV-2 transmission is mainly airborne via droplets generated by symptomatic patients, and possibly asymptomatic individuals during incubation of the disease, although for the latter, there are no certain data yet. However, research on asymptomatic viral infection is currently ongoing worldwide to elucidate the real prevalence and mortality of the disease. From a clinical point of view, COVID-19 would be defined as "COVID Planet " because it presents as a multifaceted disease, due to the large number of organs and tissues infected by the virus. Overall, based on the available published data, 80.9% of patients infected by SARS-CoV-2 develop a mild disease/infection, 13.8% severe pneumonia, 4.7% respiratory failure, septic shock, or multi-organ failure, and 3% of these cases are fatal, but mortality parameter is highly variable in different countries. Clinically, SARS-CoV-2 causes severe primary interstitial viral pneumonia and a "cytokine storm syndrome", characterized by a severe and fatal uncontrolled systemic inflammatory response triggered by the activation of interleukin 6 (IL-6) with development of endothelitis and generalized thrombosis that can lead to organ failure and death. Risk factors include advanced age and comorbidities including hypertension, diabetes, and cardiovascular disease. Virus entry occurs via binding the angiotensin-converting enzyme 2 (ACE2) receptor present in almost all tissues and organs through the Spike (S) protein. Currently, SARS-CoV-2 infection is prevented by the use of masks, social distancing, and improved hand hygiene measures. This review summarizes the current knowledge on the main biological and clinical features of the SARS-CoV-2 pandemic, also focusing on the principal measures taken in some Italian regions to face the emergency and on the most important treatments used to manage the COVID-19 pandemic.

Understanding the Pathophysiology of COVID-19: Could the Contact System Be the Key?

To date the pathophysiology of COVID-19 remains unclear: this represents a factor determining the current lack of effective treatments. In this paper, we hypothesized a complex host response to SARS-CoV-2, with the Contact System (CS) playing a pivotal role in innate immune response. CS is linked with different proteolytic defense systems operating in human vasculature: the Kallikrein–Kinin (KKS), the Coagulation/Fibrinolysis and the Renin–Angiotensin (RAS) Systems. We investigated the role of the mediators involved. CS consists of Factor XII (FXII) and plasma prekallikrein (complexed to high-molecular-weight kininogen-HK). Autoactivation of FXII by contact with SARS-CoV-2 could lead to activation of intrinsic coagulation, with fibrin formation (microthrombosis), and fibrinolysis, resulting in increased D-dimer levels. Activation of kallikrein by activated FXII leads to production of bradykinin (BK) from HK. BK binds to B2-receptors, mediating vascular permeability, vasodilation and edema. B1-receptors, binding the metabolite [des-Arg⁹]-BK (DABK), are up-regulated during infections and mediate lung inflammatory responses. BK could play a relevant role in COVID-19 as already described for other viral models. Angiotensin-Converting-Enzyme (ACE) 2 displays lung protective effects: it inactivates DABK and converts Angiotensin II (Ang II) into Angiotensin-(1-7) and Angiotensin I into Angiotensin-(1-9). SARS-CoV-2 binds to ACE2 for cell entry, downregulating it: an impaired DABK inactivation could lead to an enhanced activity of B1-receptors, and the accumulation of Ang II, through a negative feedback loop, may result in decreased ACE activity, with consequent increase of BK. Therapies targeting the CS, the KKS and action of BK could be effective for the treatment of COVID-19.

Olfactory and gustatory dysfunctions in 100 patients hospitalized for COVID-19: sex differences and recovery time in real-life

Purpose

COVID-19 displays a variety of clinical manifestations; in pauci-symptomatic patients olfactory (OD) and gustatory dysfunctions (GD) may represent the first or only symptom. This topic is currently arousing great interest, and a growing number of papers are being published. Aim of this study is to investigate the timing of recovery from OD and GD in a real-life population hospitalized for COVID-19.

Methods

We followed up by a phone interview the first 100 patients discharged a month earlier from three Italian non-intensive care wards.

Results

All 100 patients were Caucasian, mean age was 65 years, 60% were males. Forty-two patients (mean age 63 years) experienced subjective chemosensory dysfunctions (29 OD and 41 GD): the male/female ratio was 2:1; 83% reported a complete or near complete recovery at follow-up. The recovery rate was not significantly different between males and females. The mean duration of OD and GD was 18 and 16 days, respectively. The mean recovery time from OD or GD resulted significantly longer for females than for males (26 vs 14 days, P = 0.009). Among the 42 symptomatic, the mean age of males was significantly higher than that of females (66 vs 57 years, P = 0.04), while the opposite was observed in the 58 asymptomatic patients (60 vs 73 years, P = 0.0018).

Conclusions

Recovery from OD or GD was rapid, occurring within 4 weeks in most patients. Chemosensory dysfunctions in women was less frequent, but longer lasting. The value of our study is its focus on a population of hospitalized patients significantly older than those previously described, and the additional data on gender differences.

In vivo measurement of the dynamics of norepinephrine in an olfactory bulb following ischemia-induced olfactory dysfunction and its responses to dexamethasone treatment

Information on the dynamics of molecules following olfactory dysfunction remains essential for understanding the molecular events involved in the pathological process of olfactory dysfunction. This study for the first time demonstrates a method based on the combination of in vivo microdialysis with high performance liquid chromatography (HPLC) and electrochemical detection (ECD) for the measurement of the dynamics of norepinephrine (NE) in the olfactory bulbs of Sprague-Dawley rats following olfactory dysfunction induced by brain ischemia and its responses toward dexamethasone treatment. The method possesses a high spatial resolution and benefits from in vivo microdialysis and high selectivity and is thus capable of measuring NE in the olfactory bulb of rats. With this method, the basal level of NE in the olfactory bulb was evaluated to be ca. 235 ± 25 nM (n = 6). This level was found to increase by 260 ± 90% at a time point of 240 min after brain ischemia with bilateral ligation of both common carotid arteries. The increase was found to be suppressed upon the treatment of the animals with 0.2% dexamethasone in the olfactory bulb. These results suggest that NE is involved in the pathological process of ischemia-induced olfactory dysfunction and this information is useful to further understand the molecular events involved in olfactory dysfunction.

A New Approach to Treating Neurodegenerative Otologic Disorders

Hearing loss, the most common neurological disorder and the fourth leading cause of years lived with disability, can have profound effects on quality of life. The impact of this "invisible disability," with significant consequences, economic and personal, is most substantial in low- and middle-income countries, where >80% of affected people live. Given the importance of hearing for communication, enjoyment, and safety, with up to 500 million affected globally at a cost of nearly $800 billion/year, research on new approaches toward prevention and treatment is attracting increased attention. The consequences of noise pollution are largely preventable, but irreversible hearing loss can result from aging, disease, or drug side effects. Once damage occurs, treatment relies on hearing aids and cochlear implants. Preventing, delaying, or reducing some degree of hearing loss may be possible by avoiding excessive noise and addressing major contributory factors such as cardiovascular risk. However, given the magnitude of the problem, these interventions alone are unlikely to be sufficient. Recent advances in understanding principal mechanisms that govern hearing function, together with new drug discovery paradigms designed to identify efficacious therapies, bode well for pharmaceutical intervention. This review surveys various causes of loss of auditory function and discusses potential neurological underpinnings, including mitochondrial dysfunction. Mitochondria mitigate cell protection, survival, and function and may succumb to cumulative degradation of energy production and performance; the end result is cell death. Energy-demanding neurons and vestibulocochlear hair cells are vulnerable to mitochondrial dysfunction, and hearing impairment and deafness are characteristic of neurodegenerative mitochondrial disease phenotypes. Beyond acting as cellular powerhouses, mitochondria regulate immune responses to infections, and studies of this phenomenon have aided in identifying nuclear factor kappa B and nuclear factor erythroid 2-related factor 2/antioxidant response element signaling as targets for discovery of otologic drugs, respectively, suppressing or upregulating these pathways. Treatment with free radical scavenging antioxidants is one therapeutic approach, with lipoic acid and corresponding carnitine esters exhibiting improved biodistribution and other features showing promise. These compounds are also histone deacetylase (HDAC) inhibitors, adding epigenetic modulation to the mechanistic milieu through which they act. These data suggest that new drugs targeting mitochondrial dysfunction and modulating epigenetic pathways via HDAC inhibition or other mechanisms hold great promise.

Promotion of olfactory receptor neuron differentiation of olfactory neuroepithelial cells by using chitosan solution

BACKGROUND

Olfactory dysfunction significantly influences patients' quality of life. Chitosan has been reported to support neuron and Schwann cell growth and even leads to orient axonal growth. However, researchers have yet to explore whether chitosan solution can promote differentiation of olfactory receptor neurons of the olfactory neuroepithelium and be used for treating olfactory dysfunction.

OBJECTIVE

To evaluate the effect of chitosan solution on the differentiation of olfactory neuroepithelial cells.

METHOD

Olfactory neuroepithelial cells were isolated from embryonic day 17 of Wistar rats and then cultured with and without soluble chitosan for 9 days. The concentration of chitosan solution was set at 0.1 mg/mL. The effects of treatment were assessed by immunocytochemistry and Western blot after culturing.

RESULTS

The morphologic analysis indicated that olfactory neuroepithelial cells treated with chitosan exhibited bipolar shape with asymmetric processes. In addition, from days 3 to 9, the expression level of βIII tubulin gradually reduced, but the expression level of olfactory marker protein significantly rose at day 9 in the chitosan groups (p < 0.05). Importantly, chitosan-treated olfactory neuroepithelial cells expressed more signal transduction apparatuses, olfactory neuron specific-G protein and adenylate cyclase 3, than those without chitosan treatment at day 9. Western blot analysis also further confirmed the results (p < 0.05).

CONCLUSION

Experimental results revealed that soluble chitosan promoted differentiation of olfactory neuroepithelial cells based on its role in olfactory receptor neuron differentiation, neurite outgrowth, and signal transduction apparatus expressions.

Imaging Sinonasal disease with MRI: Providing insight over and above CT

This article illustrates and discusses the applications and value of magnetic resonance imaging (MRI) in the evaluation of sinonasal disease. There are several clinical scenarios where MRI can add value over conventional computed tomography (CT) evaluation of the sinonasal spaces. Specifically, MRI can provide insight through better depiction of the anatomy of certain sinonasal sub-sites including the olfactory structures. It can aid in evaluating anosmia, sinusitis (fungal sinusitis and complications), benign and malignant lesions, CSF leaks and pathology extending into sinonasal spaces.

Epigenetic Treatment of Neurodegenerative Ophthalmic Disorders: An Eye Toward the Future

Eye disease is one of the primary medical conditions that requires attention and therapeutic intervention in ageing populations worldwide. Further, the global burden of diabetes and obesity, along with heart disease, all lead to secondary manifestations of ophthalmic distress. Therefore, there is increased interest in developing innovative new approaches that target various mechanisms and sequelae driving conditions that result in adverse vision. The research challenge is even greater given that the terrain of eye diseases is difficult to landscape into a single therapeutic theme. This report addresses the burden of eye disease due to mitochondrial dysfunction, including antioxidant, autophagic, epigenetic, mitophagic, and other cellular processes that modulate the biomedical end result. In this light, we single out lipoic acid as a potent known natural activator of these pathways, along with alternative and potentially more effective conjugates, which together harness the necessary potency, specificity, and biodistribution parameters required for improved therapeutic outcomes.

The Effect of Olfactory Training on the Odor Threshold in Patients with Traumatic Anosmia

Background

Olfactory training is a novel intervention that has been used to treat olfactory dysfunction. This study attempted to investigate the effect of olfactory training in patients with traumatic anosmia.

Methods

Patients with a clear history of anosmia after experiencing a head injury and whose phenyl ethyl alcohol (PEA) odor detection thresholds were — 1 after steroid and zinc treatment were included. The patients were randomly divided into two groups, with patients in one group given a bottle of PEA and those in another group given a bottle of mineral oil for 3-month olfactory training. All the patients were followed up with a PEA threshold test and the traditional Chinese version of the University of Pennsylvania Smell Identification Test (UPSIT-TC). Magnetic resonance imaging was performed to measure the volume of the olfactory bulbs. Any patient whose PEA threshold result was below —1.01 or whose UPSIT-TC score increased four or more points was considered to have shown improvement in their olfactory function.

Results

Forty-two patients received PEA olfactory training, whereas 39 received olfactory training with mineral oil. The improvement of PEA thresholds function was observed in 10 patients within the PEA group and in 2 patients in the mineral oil group. The frequency of improvement of threshold within the PEA group was significantly higher than that of the mineral oil group. Neither olfactory bulb volume nor UPSIT-TC score was significantly different between the two groups.

Conclusion

Our results showed that olfactory training with PEA can improve PEA odor threshold levels in patients with traumatic anosmia.

The role of metals in mammalian olfaction of low molecular weight organosulfur compounds

Covering: up to the end of 2017While suggestions concerning the possible role of metals in olfaction and taste date back 50 years, only recently has it been possible to confirm these proposals with experiments involving individual olfactory receptors (ORs). A detailed discussion of recent experimental results demonstrating the key role of metals in enhancing the response of human and other vertebrate ORs to specific odorants is presented against the backdrop of our knowledge of how the sense of smell functions both at the molecular and whole animal levels. This review emphasizes the role of metals in the detection of low molecular weight thiols, sulfides, and other organosulfur compounds, including those found in strong-smelling animal excretions and plant volatiles, and those used in gas odorization. Alternative theories of olfaction are described, with evidence favoring the modified "shape" theory. The use of quantum mechanical/molecular modeling (QM/MM), site-directed mutagenesis and saturation-transfer-difference (STD) NMR is discussed, providing support for biological studies of mouse and human receptors, MOR244-3 and OR OR2T11, respectively. Copper is bound at the active site of MOR244-3 by cysteine and histidine, while cysteine, histidine and methionine are involved with OR2T11. The binding pockets of these two receptors are found in different locations in the three-dimensional seven transmembrane models. Another recently deorphaned human olfactory receptor, OR2M3, highly selective for a thiol from onions, and a broadly-tuned thiol receptor, OR1A1, are also discussed. Other topics covered include the effects of nanoparticles and heavy metal toxicants on vertebrate and fish ORs, intranasal zinc products and the loss of smell (anosmia).