Severe acute respiratory syndrome coronavirus infection causes neuronal death in the absence of encephalitis in mice transgenic for human ACE2. J Virol. 2008;82:7264-7275. [PMID: 18495771 DOI: 10.1128/jvi.00737-08]

Neuromuscular defects after infection with a beta coronavirus in mice

COVID-19 affects primarily the lung. However, several other systemic alterations, including muscle weakness, fatigue and myalgia have been reported and may contribute to the disease outcome. We hypothesize that changes in the neuromuscular system may contribute to the latter symptoms observed in COVID-19 patients. Here, we showed that C57BL/6J mice inoculated intranasally with the murine betacoronavirus hepatitis coronavirus 3 (MHV-3), a model for studying COVID-19 in BSL-2 conditions that emulates severe COVID-19, developed robust motor alterations in muscle strength and locomotor activity. The latter changes were accompanied by degeneration and loss of motoneurons that were associated with the presence of virus-like particles inside the motoneuron. At the neuromuscular junction level, there were signs of atrophy and fragmentation in synaptic elements of MHV-3-infected mice. Furthermore, there was muscle atrophy and fiber type switch with alteration in myokines levels in muscles of MHV-3-infected mice. Collectively, our results show that acute infection with a betacoronavirus leads to robust motor impairment accompanied by neuromuscular system alteration.

The Pathogenesis of COVID-19-Related Taste Disorder and Treatments

COVID-19, mainly manifested as acute respiratory distress syndrome, has afflicted millions of people worldwide since 2019. Taste dysfunction is a common early-stage symptom of COVID-19 infection that burdens patients for weeks or even permanently in some cases. Owing to its subjectivity and complexity, the mechanism of taste disorder is poorly studied. Previous studies have reported that the COVID-19 entry receptors are highly expressed in taste buds, thereby intensifying the cytocidal effect. Taste receptor cells are vulnerable to inflammation, and the COVID-19-induced cytokine storm causes secondary damage to taste function. Interferon and various proinflammatory cytokines can trigger cell apoptosis and disrupt the renewal of taste bud stem cells. This immune response can be further enhanced by the accumulation of Angiotensin II (Ang II) caused by an unbalanced local renin-angiotensin system (RAS) system. In addition, severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is neurotropic and can invade the brain through the olfactory bulb, affecting the nervous system. Other factors, such as host zinc deficiency, genetic susceptibility, sialic acid, and some neurotransmitters, also contribute to the pathogenesis process. Although several medical interventions have displayed effectiveness, only a few strategies exist for the treatment of postinfectious dysgeusia. Stem cell-based taste regeneration offers promise for long-term taste disorders. Clinical studies have demonstrated that stem cells can treat long COVID-19 through immune regulation. In dysgeusia, the differentiation of taste bud stem cells can be stimulated through exogenous epithelial-derived and neural-derived factors to regenerate taste buds. Tongue organoids are also emerging as functional taste buds, offering new insights into the study of taste regeneration. This review presents the current evidence of the pathogenesis of COVID-19-related dysgeusia, summarizes currently available treatments, and suggests future directions of taste regeneration therapy.

Insights into COVID-19: Perspectives on Drug Remedies and Host Cell Responses

In light of the COVID-19 global pandemic caused by SARS-CoV-2, ongoing research has centered on minimizing viral spread either by stopping viral entry or inhibiting viral replication. Repurposing antiviral drugs, typically nucleoside analogs, has proven successful at inhibiting virus replication. This review summarizes current information regarding coronavirus classification and characterization and presents the broad clinical consequences of SARS-CoV-2 activation of the angiotensin-converting enzyme 2 (ACE2) receptor expressed in different human cell types. It provides publicly available knowledge on the chemical nature of proposed therapeutics and their target biomolecules to assist in the identification of potentially new drugs for the treatment of SARS-CoV-2 infection.

Case Report: High-dose steroid and IVIG successful treatment in a case of COVID-19-associated autoimmune encephalitis: a literature review

Autoimmune encephalitis is a rare but critical complication of COVID-19. The management of COVID-19-associated autoimmune encephalitis includes the use of steroids, intravenous immunoglobulin (IVIG), plasmapheresis, and monoclonal antibody therapy. This study presented a patient with critical COVID-19 autoimmune encephalitis who rapidly recovered after the initiation of corticosteroids and IVIG therapy. This study reviewed the current literature on the pathophysiological mechanisms, diagnosis, and management of COVID-19-associated autoimmune encephalitis.

Neurological Manifestations of Coronavirus Disease 2019 and Mpox in Pediatric Patients and Their Management: A State-of-the-Art Systematic Review

BACKGROUND

There is an increasing number of cases being reported of neurological manifestations of Coronavirus disease 2019 (COVID-19) infection and Monkeypox (Mpox), both during the course of the infection and as a presenting symptom. We aim to review the neurological manifestations of COVID-19 and monkeypox in pediatric patients and their management.

METHODS

We conducted a systematic review that included cohort studies and case series or reports involving a pediatric population of patients with a confirmed COVID-19 or Mpox infection and their neurological manifestations. We searched the following electronic databases: PubMed, EMBASE, and Scopus.

RESULTS

From 1136 articles identified, 127 studies were included. Headache, stroke, Guillain-Barré syndrome, seizure, nerve palsies, and multisystem inflammatory syndrome in children were the most common neurological symptoms caused by COVID-19, whereas encephalitis was commonly seen in patients with Mpox. Rare neurological manifestations of COVID-19 included cerebral venous sinus thrombosis, plexopathies, demyelinating disorders, encephalitis, etc., and rare neurological manifestations of Mpox included headache.

CONCLUSIONS

Our review highlights the importance of investigating possible neurological manifestations and closely monitoring these patients to develop a better understanding of the treatment strategies that can be adopted.

Probable Neuropsychological and Cognitive Complications Due to Cytokine Storm in Patients With COVID-19

Introduction

COVID-19 (coronavirus disease 2019) was first identified in China in December 2019 and is rapidly spreading worldwide as a pandemic. Since COVID-19 causes mild to severe acute respiratory syndrome, most studies in this context have focused on pathogenesis primarily in the respiratory system. However, evidence shows that the central nervous system (CNS) may also be affected by COVID-19. Since COVID-19 is spreading, it is necessary to study its possible cognitive effects on COVID-19 patients and their recovery.

Methods

The articles used in this study were searched by keywords, such as cytokine storm and COVID-19, COVID-19 and executive dysfunction, cognitive disorder, and COVID-19, central nervous system (CNS) and COVID-19, coronavirus, neuroinvasion in Science Direct, Scopus, PubMed, Embase, and Web of Science databases based on preferred reporting items for systematic reviews and meta-analysis (PRISMA) checklist. The study evaluates all observational studies published between December 2019 and April 2021 in peer-reviewed journals, including cross-sectional, cohort, case-control studies, case reports, and case series. The search result was 106 articles, of which 73 articles related to COVID-19, the stages of infection by this virus, its effect on the nervous system and neurological symptoms, the cytokine storm caused by this infection, and the possible cognitive consequences caused by this virus in patients, has been reviewed. Other articles were not checked due to their limited relevance to the topic under discussion.

Results

Studies showed that neurons may be directly affected by severe acute respiratory syndrome coronavirus (SARS-CoV)-1 and SARS-CoV-2. Furthermore, various studies indicated that systemic inflammation (so-called "cytokine storm") is also responsible for brain damage induced by infection with SARS-CoV-1 and SARS-CoV-2. In such a way that these patients showed elevated levels of interleukin (IL-), 6, 8, and 10 and of tumor necrosis factor-alpha (TNF-α) in their blood.

Conclusion

Various cognitive defects have been observed following an increased level of cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6, 8. Therefore, due to the increased level of these pro-inflammatory factors in the brains of these patients, cognitive deficits can be expected, which need further investigation.

Case Report: Four cases of SARS-CoV-2-associated Guillain-Barré Syndrome with SARS-CoV-2-positive cerebrospinal fluid detected by metagenomic next-generation sequencing: a retrospective case series from China

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is often absent or at low levels in the cerebrospinal fluid (CSF) of patients with previous SARS-CoV-2-associated Guillain-Barré syndrome (GBS). This has led to speculation that SARS-CoV-2-associated GBS is more likely mediated by post-infectious immunity or a parainfection. This understanding has influenced the development of treatment regimens for SARS-CoV-2-associated GBS. This paper reports our experience with four Chinese patients with SARS-CoV-2-associated GBS who tested positive for SARS-CoV-2 RNA in the CSF. They developed symptoms of peripheral nerve damage 4-15 days after fever and confirmed SARS-CoV-2 infection, all of whom presented with progressive weakness of both lower limbs; three with autonomic nerve function impairment such as constipation and urination disorder; and one with polycranial neuritis and Miller-Fisher syndrome. Three patients were tested for anti-ganglioside antibodies, and one tested positive for GD1a-IgG. Four patients recovered well after treatment with anti-viral drugs combined with intravenous immunoglobulin. The present results showed that SARS-CoV-2 RNA can be detected via mNGS in the CSF of some patients with SARS-CoV-2-associated GBS, suggesting that SARS-CoV-2-associated GBS may have multiple pathogeneses.

Brain Renin-Angiotensin System: From Physiology to Pathology in Neuronal Complications Induced by SARS-CoV-2

Angiotensin-converting enzyme 2 (ACE2), a key enzyme in the renin-angiotensin system (RAS), is expressed in various tissues and organs, including the central nervous system (CNS). The spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for coronavirus disease-2019 (COVID-19), binds to ACE2, which raises concerns about the potential for viral infection in the CNS. There are numerous reports suggesting a link between SARS-CoV-2 infection and neurological manifestations. This study aimed to present an updated review of the role of brain RAS components, especially ACE2, in neurological complications induced by SARS-CoV-2 infection. Several routes of SARS-CoV-2 entry into the brain have been proposed. Because an anosmia condition appeared broadly in COVID-19 patients, the olfactory nerve route was suggested as an early pathway for SARS-CoV-2 entry into the brain. In addition, a hematogenous route via disintegrations in the blood-brain barrier following an increase in systemic cytokine and chemokine levels and retrograde axonal transport, especially via the vagus nerve innervating lungs, have been described. Common nonspecific neurological symptoms in COVID-19 patients are myalgia, headache, anosmia, and dysgeusia. However, more severe outcomes include cerebrovascular diseases, cognitive impairment, anxiety, encephalopathy, and stroke. Alterations in brain RAS components such as angiotensin II (Ang II) and ACE2 mediate neurological manifestations of SARS-CoV-2 infection, at least in part. Downregulation of ACE2 due to SARS-CoV-2 infection, followed by an increase in Ang II levels, leads to hyperinflammation and oxidative stress, which in turn accelerates neurodegeneration in the brain. Furthermore, ACE2 downregulation in the hypothalamus induces stress and anxiety responses by increasing corticotropin-releasing hormone. SARS-CoV-2 infection may also dysregulate the CNS neurotransmission, leading to neurological complications observed in severe cases of COVID-19. It can be concluded that the neurological manifestations of COVID-19 may be partially associated with changes in brain RAS components.

Vertigo symptom scores and videonystagmographic examinations in recovered coronavirus disease 2019 patients

OBJECTIVE

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) may be among the viral agents that affect the audio-vestibular system. This study aimed to investigate vestibular symptoms and videonystagmographic examinations in recovered coronavirus disease 2019 (Covid-19) patients compared with the control group.

METHOD

The patients were evaluated with Vertigo Symptom Scale questionnaire and audiometric, tympanometric, stapedial reflex and videonystagmographic examinations.

RESULTS

A total of 92 of the patients in the coronavirus disease 2019 patients group and 25 of the volunteers in the control group were included in the study. The mean Vertigo Symptom Scale score was found to be significantly higher (p < 0.001) in the coronavirus disease 2019 group. Furthermore, one of the hospitalised patients was diagnosed with vestibular neuritis.

CONCLUSION

The vestibular system may also be affected in some coronavirus disease 2019 patients. Although this may be seen as dizziness in some patients, in rare cases it can cause severe issues, such as vestibular neuritis.

Incidence of Delirium in Critically Ill Patients With and Without COVID-19

BACKGROUND

It is known that patients with COVID-19 are at high risk of developing delirium. The aim of the study was to compare the incidence of delirium between critically ill patients with and without a diagnosis of COVID-19.

METHODS

This is a retrospective study conducted in a southern Brazilian hospital from March 2020 to January 2021. Patients were divided into two groups: the COVID-19 group consisted of patients with a diagnosis of COVID-19 confirmed by reverse transcription-polymerase chain reaction (RT-PCR) or serological tests who were admitted to specific ICUs. The non-COVID-19 group consisted of patients with other surgical and medical diagnoses who were admitted to non-COVID ICUs. All patients were evaluated daily using the Intensive Care Delirium Screening Checklist (ICDSC). The two cohorts were compared in terms of the diagnosis of delirium.

RESULTS

Of the 649 patients who remained more than 48 h in the ICU, 523 were eligible for the study (COVID-19 group: 292, non-COVID-19 group: 231). There were 119 (22.7%) patients who had at least one episode of delirium, including 96 (32.9%) in the COVID-19 group and 23 (10.0%) in the non-COVID-19 group (odds ratio [OR] 4.42; 95% confidence interval [CI], 2.69 to 7.26; p < 0.001). Among patients mechanically ventilated for two days or more, the incidence of delirium did not differ between groups (COVID-19: 89/211, 42.1% vs non-COVID-19: 19/47, 40.4%; p  =  0.82). Logistic regression showed that the duration of mechanical ventilation was the only independent factor associated with delirium (p  =  0.001).

CONCLUSION

COVID-19 can be associated with a higher incidence of delirium among critically ill patients, but there was no difference in this incidence between groups when mechanical ventilation lasted two days or more.

The relationship between sublingual immunotherapy for allergic rhinitis and the risk of symptoms in patients with COVID-19 infection

To evaluated the risk ratio of Allergic rhinitis (AR) people on the symptoms after COVID-19 infection, and explored the relationship between AR and the symptoms after COVID-19 infection. An observational study was performed of people from outpatient department of the Hospital of Chengdu University of Chinese Medicine. Participants completed an electronic survey and between January 10 to January 20, 2023. We divided the participants into three groups according to the disease information of the population: non-AR people group (AR-N), AR patients with sublingual immunotherapy group (AR-S), and AR patients with conventional therapy group (AR-C). A total of 1116 participants were included in the study, with an average age of 21.76 ± 8.713, women accounted for 62.5%, men accounted for 37.5%. The final results showed that the risk of most symptoms after AR-C infection was not different from that of AR-N, except for sore throat, dry and itchy, chest distress, shortness of breath, and dyspnea. AR-S could effectively reduce the risk of post-infection symptoms including: dry and itchy (OR = 0.484, 95%CI: 0.335-0.698), pain (OR = 0.513, 95%CI:0.362-0.728), cough (OR = 0.506, 95% CI:0.341-0.749), expectoration (OR = 0.349, 95% CI:0.244-0.498), fever (OR = 0.569, 95% CI:0.379-0.853), head and body pain (OR = 0.456, 95% CI:0.323-0.644), fatigue (OR = 0.256, 95% CI:0.177-0.371), cold limbs (OR = 0.325, 95%CI:0.227-0.465), diarrhea (OR = 0.246, 95% CI:0.132-0.457), constipation (OR = 0.227, 95%CI:0.100-0.513), hyposmia (OR = 0.456, 95% CI:0.296-0.701), hypogeusia (OR = 0.397, 95% CI:0.259-0.607), chest distress (OR = 0.534, 95% CI:0.343-0.829), shortness of breath (OR = 0.622, 95% CI:0.398-0.974), palpitations (OR = 0.355, 95% CI:0.206-0.613). The risk of symptoms after COVID-19 infection in allergic rhinitis population receiving sublingual immunotherapy is lower.

Enteric nervous system as a target and source of SARS-CoV-2 and other viral infections

Coronavirus disease 2019 (COVID-19) has been demonstrated to affect several systems of the human body, including the gastrointestinal and nervous systems. The enteric nervous system (ENS) is a division of the autonomic nervous system that extends throughout the gut, regulates gastrointestinal function, and is therefore involved in most gut dysfunctions, including those resulting from many viral infections. Growing evidence highlights enteric neural cells and microbiota as important players in gut inflammation and dysfunction. Furthermore, the ENS and gastrointestinal immune system work together establishing relevant neuroimmune interactions during both health and disease. In recent years, gut-driven processes have also been implicated as players in systemic inflammation and in the initiation and propagation of several central nervous system pathologies, which seem to be hallmarks of COVID-19. In this review, we aim to describe evidence of the gastrointestinal and ENS infection with a focus on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We discuss here viral-induced mechanisms, neuroplasticity, and neuroinflammation to call attention to the enteric neuroglial network as a nervous system with a sensitive and crucial position to be not only a target of the new coronavirus but also a way in and trigger of COVID-19-related symptoms.

Post-infection treatment with the E protein inhibitor BIT225 reduces disease severity and increases survival of K18-hACE2 transgenic mice infected with a lethal dose of SARS-CoV-2

The Coronavirus envelope (E) protein is a small structural protein with ion channel activity that plays an important role in virus assembly, budding, immunopathogenesis and disease severity. The viroporin E is also located in Golgi and ER membranes of infected cells and is associated with inflammasome activation and immune dysregulation. Here we evaluated in vitro antiviral activity, mechanism of action and in vivo efficacy of BIT225 for the treatment of SARS-CoV-2 infection. BIT225 showed broad-spectrum direct-acting antiviral activity against SARS-CoV-2 in Calu3 and Vero cells with similar potency across 6 different virus strains. BIT225 inhibited ion channel activity of E protein but did not inhibit endogenous currents or calcium-induced ion channel activity of TMEM16A in Xenopus oocytes. BIT225 administered by oral gavage for 12 days starting 12 hours before infection completely prevented body weight loss and mortality in SARS-CoV-2 infected K18 mice (100% survival, n = 12), while all vehicle-dosed animals reached a mortality endpoint by Day 9 across two studies (n = 12). When treatment started at 24 hours after infection, body weight loss, and mortality were also prevented (100% survival, n = 5), while 4 of 5 mice maintained and increased body weight and survived when treatment started 48 hours after infection. Treatment efficacy was dependent on BIT225 dose and was associated with significant reductions in lung viral load (3.5 log10), virus titer (4000 pfu/ml) and lung and serum cytokine levels. These results validate viroporin E as a viable antiviral target and support the clinical study of BIT225 for treatment and prophylaxis of SARS-CoV-2 infection.

Cognitive impairment after long COVID-19: current evidence and perspectives

COVID-19, caused by the SARS-CoV-2 virus, is a respiratory infectious disease. While most patients recover after treatment, there is growing evidence that COVID-19 may result in cognitive impairment. Recent studies reveal that some individuals experience cognitive deficits, such as diminished memory and attention, as well as sleep disturbances, suggesting that COVID-19 could have long-term effects on cognitive function. Research indicates that COVID-19 may contribute to cognitive decline by damaging crucial brain regions, including the hippocampus and anterior cingulate cortex. Additionally, studies have identified active neuroinflammation, mitochondrial dysfunction, and microglial activation in COVID-19 patients, implying that these factors may be potential mechanisms leading to cognitive impairment. Given these findings, the possibility of cognitive impairment following COVID-19 treatment warrants careful consideration. Large-scale follow-up studies are needed to investigate the impact of COVID-19 on cognitive function and offer evidence to support clinical treatment and rehabilitation practices. In-depth neuropathological and biological studies can elucidate precise mechanisms and provide a theoretical basis for prevention, treatment, and intervention research. Considering the risks of the long-term effects of COVID-19 and the possibility of reinfection, it is imperative to integrate basic and clinical research data to optimize the preservation of patients' cognitive function and quality of life. This integration will also offer valuable insights for responding to similar public health events in the future. This perspective article synthesizes clinical and basic evidence of cognitive impairment following COVID-19, discussing potential mechanisms and outlining future research directions.

COVID-19 and Neurological Manifestations

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a newly emerged coronavirus, has sparked a global pandemic with its airborne transmission and ability to infect with asymptomatic patients. The pathophysiology is thought to relate to the binding of angiotensin converting enzyme 2 (ACE2) receptors in the body. These receptors are widely expressed in various body organs such as the lungs, the heart, the gastrointestinal tract (GIT), and the brain. This article reviews the current knowledge on the symptoms of coronavirus disease 2019 (COVID-19), highlighting the neurological symptoms that are associated with COVID-19, and discussing the possible mechanisms for SARS-CoV-2 virus infection in the body.

Schizophrenia and the COVID-19 pandemic: A narrative review from the biomedical perspective

The outbreak of the Coronavirus Disease 2019 (COVID-19) pandemic in 2020 caused a rapid worsening of global mental health. Patients with severe mental disorders, including schizophrenia, are at higher risk of being infected. The neuroinvasive potential of the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) has been confirmed. The aim of this article was to present a narrative and comprehensive review of multidimensional associations between schizophrenia and COVID-19 with special emphasis on common biological pathways. Online searches were performed in the PubMed database and covered the publication period until September 17, 2022. Search terms included "psychosis", "schizophrenia", "inflammation" and "COVID-19". Viewed as a neuroinflammatory state, schizophrenia shares several neurobiological mechanisms with the COVID-19. Environmental stress, common comorbidities of schizophrenia and adverse effects of antipsychotic treatment are associated with the higher severity and mortality of the COVID-19. Additionally, more frequent relapses of psychosis have been observed, and might be related to lower treatment adherence. In the context of clinical manifestation, higher level of negative symptoms has been identified among patients with schizophrenia during the pandemic. Improvements in mental health care policy and treatment adjustment are necessary to protect people with schizophrenia who are the population that is particularly vulnerable to the consequences of the COVID-19 pandemic. Future research will show if prenatal infection with the SARS-CoV-2 increases a risk of psychosis.

Respiratory issues in patients with multiple sclerosis as a risk factor during SARS-CoV-2 infection: a potential role for exercise

Coronavirus disease-2019 (COVID-19) is associated with cytokine storm and is characterized by acute respiratory distress syndrome (ARDS) and pneumonia problems. The respiratory system is a place of inappropriate activation of the immune system in people with multiple sclerosis (MS), and this may cause damage to the lung and worsen both MS and infections.The concerns for patients with multiple sclerosis are because of an enhance risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The MS patients pose challenges in this pandemic situation, because of the regulatory defect of autoreactivity of the immune system and neurological and respiratory tract symptoms. In this review, we first indicate respiratory issues associated with both diseases. Then, the main mechanisms inducing lung damages and also impairing the respiratory muscles in individuals with both diseases is discussed. At the end, the leading role of physical exercise on mitigating respiratory issues inducing mechanisms is meticulously evaluated.

Intranasal soluble ACE2 improves survival and prevents brain SARS-CoV-2 infection

A soluble ACE2 protein bioengineered for long duration of action and high affinity to SARS-CoV-2 was administered either intranasally (IN) or intraperitoneally (IP) to SARS-CoV-2-inoculated k18hACE2 mice. This decoy protein (ACE2 618-DDC-ABD) was given either IN or IP, pre- and post-inoculation, or IN, IP, or IN + IP but only post-inoculation. Survival by day 5 was 0% in untreated mice, 40% in the IP-pre, and 90% in the IN-pre group. In the IN-pre group, brain histopathology was essentially normal and lung histopathology significantly improved. Consistent with this, brain SARS-CoV-2 titers were undetectable and lung titers reduced in the IN-pre group. When ACE2 618-DDC-ABD was administered only post-inoculation, survival was 30% in the IN + IP, 20% in the IN, and 20% in the IP group. We conclude that ACE2 618-DDC-ABD results in markedly improved survival and provides organ protection when given intranasally as compared with when given either systemically or after viral inoculation, and that lowering brain titers is a critical determinant of survival and organ protection.

Transient Anosmia and Dysgeusia in COVID-19 Disease: A Cross Sectional Study

Objective

This study aims to explore the prevalence of anosmia and dysgeusia and their impact on COVID-19 patients.

Methods

This is a cross-sectional study. Patients diagnosed with COVID-19 between 1st October 2020 and 30th June 2021 were randomly selected from a national COVID-19 registry. COVID-19 cases were diagnosed using molecular testing method which measured the viral E gene. The Anosmia Reporting Tool, and a brief version of the questionnaire on olfactory disorders were used to measure the outcomes via telephone interviews. Data were analysed using SPSS 27 statistics software.

Results

A total of 405 COVID-19 adults were included in this study, 220 (54.3%) were males and 185 (45.8%) were females. The mean±SD age of participants was 38.2 ± 11.3 years. Alterations in the sense of smell and taste were reported by 206 (50.9%), and 195 (48.1%) of the patients, respectively. Sex and nationality of participants were significantly associated with anosmia and dysgeusia (p < 0.001) and (p-value=0.001) respectively. Among patients who experienced anosmia and dysgeusia, alterations in eating habits (64.2%), impact on mental wellbeing (38.9%), concerns that the alterations were permanent (35.4%), and physical implications and difficulty performing activities of daily living (34%) were reported.

Conclusion

Anosmia and dysgeusia are prevalent symptoms of COVID-19 disease, especially among females. Although transient, anosmia and dysgeusia had considerable impact on patient's life. Neuropsychological implications of COVID-19 in acute infection phase and prognosis of anosmia and dysgeusia in COVID-19 are areas for further exploration.

COVID-19: Mechanisms, risk factors, genetics, non-coding RNAs and neurologic impairments

The novel coronavirus infection (COVID-19) causes a severe acute illness with the development of respiratory distress syndrome in some cases. COVID-19 is a global problem of mankind to this day. Among its most important aspects that require in-depth study are pathogenesis and molecular changes in severe forms of the disease. A lot of literature data is devoted to the pathogenetic mechanisms of COVID-19. Without dwelling in detail on some paths of pathogenesis discussed, we note that at present there are many factors of development and progression. Among them, this is the direct role of both viral non-coding RNAs (ncRNAs) and host ncRNAs. One such class of ncRNAs that has been extensively studied in COVID-19 is microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Moreover, Initially, it was believed that this COVID-19 was limited to damage to the respiratory system. It has now become clear that COVID-19 affects not only the liver and kidneys, but also the nervous system. In this review, we summarized the current knowledge of mechanisms, risk factors, genetics and neurologic impairments in COVID-19. In addition, we discuss and evaluate evidence demonstrating the involvement of miRNAs and lnRNAs in COVID-19 and use this information to propose hypotheses for future research directions.

The Risk Factors for Acute Cerebrovascular Accident (Stroke) in Patients with Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2)

Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) patients may experience an acute ischemic stroke; however, risk factors, in-hospital deaths, and outcomes have not been thoroughly investigated. This study investigates the risk factors, comorbidities, and outcomes in patients with SARS-VoV-2 infection and acute ischemic stroke compared to patients without these conditions. The present retrospective study was conducted in the King Abdullah International Medical Research Centre (KAIMRC), Ministry of National Guard, Health Affairs, Riyadh, Saudi Arabia, during the period from April 2020 to February 2022. This study investigates the risk variables among the individuals who were diagnosed with either SARS-CoV-2 with stroke or patients with stroke alone. A total of 42,688 COVID-19 patients were registered, 187 cases of strokes were listed in COVID-19 patients, however, 5395 cases with stroke without SARS-CoV-2 infection. The results revealed that factors including age, hypertension, deep vein thrombosis, and ischemic heart disease are associated with an increased risk of ischemic stroke. The results also displayed an elevated frequency of in-hospital deaths in COVID-19 patients with acute ischemic stroke. The results also showed that SARS-CoV-2 together predicts the probability of stroke and death in the study sample. The study findings conclude that ischemic strokes were infrequent in patients with SARS-CoV-2 and usually occur in the presence of other risk factors. The risk factors of ischemic strokes in patients with SARS-CoV-2 are old age, male gender, hypertension, hyperlipidaemia, DVT, ischemic heart disease, and diabetes mellitus. Furthermore, the results showed a higher frequency of in-hospital deaths in COVID-19 patients with stroke compared to COVID-19 patients without stroke.

Post-COVID-19 persistent olfactory, gustatory, and trigeminal chemosensory disorders: Definitions, mechanisms, and potential treatments

The nose and the oral cavities are the main sites for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry into the body. Smell and taste deficits are the most common acute viral manifestations. Persistent smell disorders are the most common and bothersome complications after SARS-CoV-2 infection, lasting for months to years. The mechanisms and treatment of persistent post-coronavirus disease 2019 (COVID-19) smell and taste disorders are still challenges. Information sources for the review are PubMed, Centers for Disease Control and Prevention, Ovid Medline, Embase, Scopus, Web of Science, International Prospective Register of Systematic Reviews, Cumulative Index to Nursing and Allied Health Literature, Elton Bryson Stephens Company, Cochrane Effective Practice and Organization of Care, Cooperation in Science and Technology, International Clinical Trials Registry Platform, World Health Organization, Randomized Controlled Trial Number Registry, and MediFind. This review summarizes the up-to-date information about the prevalence, patterns at onset, and prognoses of post-COVID-19 smell and taste disorders, evidence for the neurotropism of SARS-CoV-2 and the overlap between SARS-CoV-1, Middle East respiratory syndrome coronavirus, and SARS-CoV-2 in structure, molecular biology, mode of replication, and host pathogenicity, the suggested cellular and molecular mechanisms for these post-COVID19 chemosensory disorders, and the applied pharmacotherapies and interventions as trials to treat these disorders, and the recommendations for future research to improve understanding of predictors and mechanisms of these disorders. These are crucial for hopeful proper treatment strategies.

The Impact of COVID-19 on People Living with HIV-1 and HIV-1-Associated Neurological Complications

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the causative pathogen of the coronavirus disease 2019 (COVID-19) pandemic, a fatal respiratory illness. The associated risk factors for COVID-19 are old age and medical comorbidities. In the current combined antiretroviral therapy (cART) era, a significant portion of people living with HIV-1 (PLWH) with controlled viremia is older and with comorbidities, making these people vulnerable to SARS-CoV-2 infection and COVID-19-associated severe outcomes. Additionally, SARS-CoV-2 is neurotropic and causes neurological complications, resulting in a health burden and an adverse impact on PLWH and exacerbating HIV-1-associated neurocognitive disorder (HAND). The impact of SARS-CoV-2 infection and COVID-19 severity on neuroinflammation, the development of HAND and preexisting HAND is poorly explored. In the present review, we compiled the current knowledge of differences and similarities between SARS-CoV-2 and HIV-1, the conditions of the SARS-CoV-2/COVID-19 and HIV-1/AIDS syndemic and their impact on the central nervous system (CNS). Risk factors of COVID-19 on PLWH and neurological manifestations, inflammatory mechanisms leading to the neurological syndrome, the development of HAND, and its influence on preexisting HAND are also discussed. Finally, we have reviewed the challenges of the present syndemic on the world population, with a particular emphasis on PLWH.

The Effects of Extrinsic and Intrinsic Factors on Neurogenesis

In the mammalian brain, neurogenesis is maintained throughout adulthood primarily in two typical niches, the subgranular zone (SGZ) of the dentate gyrus and the subventricular zone (SVZ) of the lateral ventricles and in other nonclassic neurogenic areas (e.g., the amygdala and striatum). During prenatal and early postnatal development, neural stem cells (NSCs) differentiate into neurons and migrate to appropriate areas such as the olfactory bulb where they integrate into existing neural networks; these phenomena constitute the multistep process of neurogenesis. Alterations in any of these processes impair neurogenesis and may even lead to brain dysfunction, including cognitive impairment and neurodegeneration. Here, we first summarize the main properties of mammalian neurogenic niches to describe the cellular and molecular mechanisms of neurogenesis. Accumulating evidence indicates that neurogenesis plays an integral role in neuronal plasticity in the brain and cognition in the postnatal period. Given that neurogenesis can be highly modulated by a number of extrinsic and intrinsic factors, we discuss the impact of extrinsic (e.g., alcohol) and intrinsic (e.g., hormones) modulators on neurogenesis. Additionally, we provide an overview of the contribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection to persistent neurological sequelae such as neurodegeneration, neurogenic defects and accelerated neuronal cell death. Together, our review provides a link between extrinsic/intrinsic factors and neurogenesis and explains the possible mechanisms of abnormal neurogenesis underlying neurological disorders.

Long-Term Effects of SARS-CoV-2 in the Brain: Clinical Consequences and Molecular Mechanisms

Numerous investigations have demonstrated significant and long-lasting neurological manifestations of COVID-19. It has been suggested that as many as four out of five patients who sustained COVID-19 will show one or several neurological symptoms that can last months after the infection has run its course. Neurological symptoms are most common in people who are less than 60 years of age, while encephalopathy is more common in those over 60. Biological mechanisms for these neurological symptoms need to be investigated and may include both direct and indirect effects of the virus on the brain and spinal cord. Individuals with Alzheimer's disease (AD) and related dementia, as well as persons with Down syndrome (DS), are especially vulnerable to COVID-19, but the biological reasons for this are not clear. Investigating the neurological consequences of COVID-19 is an urgent emerging medical need, since close to 700 million people worldwide have now had COVID-19 at least once. It is likely that there will be a new burden on healthcare and the economy dealing with the long-term neurological consequences of severe SARS-CoV-2 infections and long COVID, even in younger generations. Interestingly, neurological symptoms after an acute infection are strikingly similar to the symptoms observed after a mild traumatic brain injury (mTBI) or concussion, including dizziness, balance issues, anosmia, and headaches. The possible convergence of biological pathways involved in both will be discussed. The current review is focused on the most commonly described neurological symptoms, as well as the possible molecular mechanisms involved.

Acute Vertigo in a Patient Following COVID-19 Infection: A Case Report and Literature Review

COVID-19 has infected millions of people worldwide causing millions of deaths. COVID-19 has many serious effects on organs of the body especially the respiratory system causing pneumonia and acute respiratory distress syndrome (ARDS). The disease also has severe complications on other different organs; kidneys and liver which may end in multi-organ failure. Most common symptoms that have been detected in large section of patients were fever, cough and loss of taste or smell and less commonly sore throat, headache and muscle pain. The incidence of vertigo or dizziness is a rare symptom of COVID-19. In this case report, we introduce a 59-year-old male patient suffering from acute vertigo attack after COVID-19 infection. The patient had negative medical history of vertigo and any ear diseases. The patient received REGEN-COV (casirivimab and imdevimab) for COVID-19 and meclizine for vertigo. Vertigo attacks lasted for the two weeks follow up after disappearance of COVID-19 symptoms despite receiving vertigo medication. In conclusion, vertigo may be the sole neurological manifestation of COVID-19. More observational studies should address this symptom and researchers should also focus on identifying the origin of developing vertigo and the direct or indirect mechanisms that SARS-CoV-2 triggers to develop dizziness in general. This research should deliver a clear message, especially to ER physicians to consider proper referral of these patients without underestimating the risk of developing more serious COVID-19 symptoms as ARDS and multi-organ failure if no proper testing and follow-up are provided.

Infection routes, invasion mechanisms, and drug inhibition pathways of human coronaviruses on the nervous system

So far, numerous studies have reported on how coronaviruses affect the human nervous system. However, these studies mainly focused on the impact of a single coronavirus on the nervous system, and failed to fully report the invasion mechanisms and the rules of symptoms of the seven human coronaviruses. This research can assist medical professionals in identifying the regularity of coronavirus invasion into the nervous system by examining the impacts of human coronaviruses on the nervous system. Meanwhile, the discovery also helps humans to prevent the damage to the human nervous system caused by the more novel coronavirus in advance, thus reducing the rate of disease transmission and fatality caused by such viruses. In addition to describing the structures, routes of infection, and symptomatic manifestations of human coronaviruses, this review also finds that the structures of human coronaviruses correlate with virulence, pathways of infection, and blocking mechanisms of drugs. This review can provide a theoretical basis for the research and development of related drugs, promote the prevention and treatment of coronavirus infectious diseases, and contribute to global epidemic prevention.

Shared molecular signatures between coronavirus infection and neurodegenerative diseases provide targets for broad-spectrum drug development

Growing evidences have suggested the association between coronavirus infection and neurodegenerative diseases. However, the molecular mechanism behind the association is complex and remains to be clarified. This study integrated human genes involved in infections of three coronaviruses including SARS-CoV-2, SARS-CoV and MERS-CoV from multi-omics data, and investigated the shared genes and molecular functions between coronavirus infection and two neurodegenerative diseases, namely Alzheimer's Disease (AD) and Parkinson's Disease (PD). Seven genes including HSP90AA1, ALDH2, CAV1, COMT, MTOR, IGF2R and HSPA1A, and several inflammation and stress response-related molecular functions such as MAPK signaling pathway, NF-kappa B signaling pathway, responses to oxidative or chemical stress were common to both coronavirus infection and neurodegenerative diseases. These genes were further found to interact with more than 20 other viruses. Finally, drugs targeting these genes were identified. The study would not only help clarify the molecular mechanism behind the association between coronavirus infection and neurodegenerative diseases, but also provide novel targets for the development of broad-spectrum drugs against both coronaviruses and neurodegenerative diseases.

Depression and Anxiety During the COVID-19 Pandemic: Epidemiology, Mechanism, and Treatment

The Coronavirus Disease 2019 (COVID-19) pandemic has had an adverse impact on the physical and mental health of the public worldwide. In addition to illness in patients with COVID-19, isolated people and the general population have experienced mental health problems due to social distancing policies, mandatory lockdown, and other psychosocial factors, and the prevalence of depression and anxiety significantly increased during the pandemic. The purpose of this review is to elucidate the epidemiology, contributing factors, and pathogenesis of depression and anxiety. during the pandemic. These findings indicate that physicians and psychiatrists should pay more attention to and identify those with a high risk for mental problems, such as females, younger people, unmarried people, and those with a low educational level. In addition, researchers should focus on identifying the neural and neuroimmune mechanisms involved in depression and anxiety, and assess the intestinal microbiome to identify effective biomarkers. We also provide an overview of various intervention methods, including pharmacological treatment, psychological therapy, and physiotherapy, to provide a reference for different populations to guide the development of optimized intervention methods.

Central Apnea in Patients with COVID-19 Infection

Background: The Coronavirus Disease 2019 (COVID-19) is a global pandemic that has killed over 1.5 million people worldwide. A constellation of multisystem involvement with SARS-CoV-2 has been reported. COVID-19 has been shown to affect the human nervous system, however, both the extent and severity of involvement have yet to be fully elucidated. In this manuscript, we aimed to better understand the effect of COVID-19 on neuro-respiratory status by studying COVID-19 patients who presented with central apnea. Methodology: We analyzed patient characteristics, clinical outcomes, laboratory results, and imaging results of three patients with symptomatic, PCR-proven COVID-19 and episodes of central apnea. Results: Of the three patients included in this study, two patients developed new central apnea, and one patient developed an exacerbation of underlying central apnea despite COVID-19 treatments with systemic steroids and remdesivir. All occurred, on average, 15 days after the onset of COVID-19 symptoms. At 1-year follow-up, all patients experienced complete resolution of apneic breathing. Conclusions: Physicians should be vigilant for the presentation of COVID-19 with central apnea. Central apnea may be a complication in patients with severe COVID-19 infection. More research is warranted to further understand this association.

Mapping peripheral and abdominal sarcopenia acquired in the acute phase of COVID-19 during 7 days of mechanical ventilation

Our aim was to map acquired peripheral and abdominal sarcopenia in mechanically ventilated adults with COVID-19 through ultrasound measurements. On Days 1, 3, 5 and 7 after admission to critical care, the muscle thickness and cross-sectional area of the quadriceps, rectus femoris, vastus intermedius, tibialis anterior, medial and lateral gastrocnemius, deltoid, biceps brachii, rectus abdominis, internal and external oblique, and transversus abdominis were measured using bedside ultrasound. A total of 5460 ultrasound images were analyzed from 30 patients (age: 59.8 ± 15.6 years; 70% men). Muscle thickness loss was found in the bilateral anterior tibial and medial gastrocnemius muscles (range 11.5-14.6%) between Days 1 and 3; in the bilateral quadriceps, rectus femoris, lateral gastrocnemius, deltoid, and biceps brachii (range 16.3-39.1%) between Days 1 and 5; in the internal oblique abdominal (25.9%) between Days 1 and 5; and in the rectus and transversus abdominis (29%) between Days 1 and 7. The cross-sectional area was reduced in the bilateral tibialis anterior and left biceps brachii (range 24.6-25.6%) between Days 1 and 5 and in the bilateral rectus femoris and right biceps brachii (range 22.9-27.7%) between Days 1 and 7. These findings indicate that the peripheral and abdominal muscle loss is progressive during the first week of mechanical ventilation and is significantly higher in the lower limbs, left quadriceps and right rectus femoris muscles in critically ill patients with COVID-19.

Thymus vulgaris, a natural pharmacy against COVID-19: A molecular review

Introduction

A worldwide pandemic infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of a deadly disease called COVID-19. Interaction of the virus and the Angiotensin converting-enzyme 2 (ACE2) receptor leads to an inflammatory-induced tissue damage. Thymus vulgaris L. (TvL) is a plant with a long history in traditional medicine that has antimicrobial, antiseptic, and antiviral properties. Thymol and Carvacrol are two important biological components in Thyme that have anti-inflammatory, antioxidant, and immunomodulatory properties. This study is a molecular review on the potential effects of TvL and its active compounds on SARS-COV2 infection.

Method

This is a narrative review in which using PubMed, Scopus, ISI, Cochrane, ScienceDirect, Google scholar, and Arxiv preprint databases, the molecular mechanisms of therapeutic and protective effects of TvL and its active compounds have been discussed regarding the molecular pathogenesis in COVID-19.

Results

Thyme could suppress TNF-alpha, IL-6, and other inflammatory cytokines. It also enhances the anti-inflammatory cytokines like TGF-beta and IL-10. Thyme extract acts also as an inhibitor of cytokines IL-1-beta and IL-8, at both mRNA and protein levels. Thymol may also control the progression of neuro-inflammation toward neurological disease by reducing some factors. Thyme and its active ingredients, especially Thymol and Carvacrol, have also positive effects on the renin-angiotensin system (RAS) and intestinal microbiota.

Conclusions

Accordingly, TvL and its bioactive components may prevent COVID-19 complications and has a potential protective role against the deleterious consequences of the disease.

Gastrointestinal, Respiratory, and Olfactory Neurotropism of Sars-Cov2 as a Possible Trigger of Parkinson's Disease: Is a Multi-Hit Multi-Step Process on the Cards

Since the first emergence of COVID-19 on the global stage, there has been a wealth of evidence to suggest that SARS-Cov2 is not merely a pulmonary pathogen. This virus is unique in its ability to disrupt cellular pathways related to protein homeostasis, mitochondrial function, stress response, and aging. Such effects raise concerns about the long-term fate of survivors of COVID-19 infection, particularly regarding neurodegenerative diseases. The concept of interaction between environmental factors and alpha-synuclein formation in the olfactory bulb and vagal autonomic terminals with subsequent caudo-cranial migration has received much attention in the context of PD pathogenesis. Anosmia and gastrointestinal symptoms are two well-known symptoms of COVID-19, with evidence of an olfactory bulb and vagal infiltration by SARS-CoV2. This raises the possibility of the spread of the viral particles to the brain along multiple cranial nerve routes. Neurotropism, coupled with the ability of the SARS-Cov2 virion to induce abnormal protein folding and stress responses in the central nervous system, in presence of an inflammatory milieu, reinforced by hypoxia, coagulopathy, and endothelial dysfunction, reverberates the intriguing possibility of activation of a neurodegenerative cascade leading to the development of pathological alpha-synuclein aggregates and thus, triggering the development of PD in survivors of COVID19. This review attempts to summarize and critically appraise existing evidence from basic science research and clinical reports of links between COVID-19 and PD and explores the prospect of a multi-hit pathophysiological process, induced by SARS-Cov2 infection, ultimately converging on perturbed cellular protein homeostasis, which although is intriguing, presently lacks robust evidence for confirmation.

The regulation of host cytoskeleton during SARS-CoV-2 infection in the nervous system

The global economy and public health are currently under enormous pressure since the outbreak of COVID-19. Apart from respiratory discomfort, a subpopulation of COVID-19 patients exhibits neurological symptoms such as headache, myalgia, and loss of smell. Some have even shown encephalitis and necrotizing hemorrhagic encephalopathy. The cytoskeleton of nerve cells changes drastically in these pathologies, indicating that the cytoskeleton and its related proteins are closely related to the pathogenesis of nervous system diseases. In this review, we present the up-to-date association between host cytoskeleton and coronavirus infection in the context of the nervous system. We systematically summarize cytoskeleton-related pathogen-host interactions in both the peripheral and central nervous systems, hoping to contribute to the development of clinical treatment in COVID-19 patients.

[The alleged mechanisms of olfactory disorders in the new coronavirus infection]

In March 2020, the World Health Organization (WHO) announced the beginning of the COVID-19 pandemic, which continues to the present. A change in the sense of smell, up to the complete disappearance of odors, is regarded as one of the early symptoms of the disease. Sometimes anosmia was the only sign of infection of the patient. As is known, a disturbance of the sense of smell indicates a serious pathology of the brain, such as the consequences of traumatic brain injuries, strokes, Alzheimer's disease, Parkinson's disease, autoimmune diseases, a side-effect of drug therapy. The review is dedicated to the pathogenesis of anosmia in COVID-19. For a better understanding of the pathogenesis, the article presents a brief anatomy and physiology of the olfactory organ as well as the probable mechanisms of anosmia: encephalitis, inflammatory edema of the olfactory cleft, olfactory epithelium damage, apoptosis of bipolar neurons, damage of olfactory cell cilia and damage of olfactory bulbs. Because of the rapid accumulation of information on this topic, there is a need to structure, periodic systematization and presentation to a wide range of specialists.

The Latest Cellular and Molecular Mechanisms of COVID-19 on Non-Lung Organs

Understanding the transmission pathways of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will aid in developing effective therapies directed at the virus’s life cycle or its side effects. While severe respiratory distress is the most common symptom of a coronavirus 2019 (COVID-19) infection, the virus is also known to cause damage to almost every major organ and system in the body. However, it is not obvious whether pathological changes in extra-respiratory organs are caused by direct infection, indirect, or combination of these effects. In this narrative review, we first elaborate on the characteristics of SARS-CoV-2, followed by the mechanisms of this virus on various organs such as brain, eye, and olfactory nerve and different systems such as the endocrine and gastrointestinal systems.

How viral infections cause neuronal dysfunction: a focus on the role of microglia and astrocytes

In recent decades, a number of infectious viruses have emerged from wildlife or reemerged that pose a serious threat to global health and economies worldwide. Although many of these viruses have a specific target tissue, neurotropic viruses have evolved mechanisms to exploit weaknesses in immune defenses that eventually allow them to reach and infect cells of the central nervous system (CNS). Once in the CNS, these viruses can cause severe neuronal damage, sometimes with long-lasting, life-threatening consequences. Remarkably, the ability to enter the CNS and cause neuronal infection does not appear to determine whether a viral strain causes neurological complications. The cellular mechanisms underlying the neurological consequences of viral infection are not fully understood, but they involve neuroimmune interactions that have so far focused mainly on microglia. As the major immune cells in the brain, reactive microglia play a central role in neuroinflammation by responding directly or indirectly to viruses. Chronic reactivity of microglia leads to functions that are distinct from their beneficial roles under physiological conditions and may result in neuronal damage that contributes to the pathogenesis of various neurological diseases. However, there is increasing evidence that reactive astrocytes also play an important role in the response to viruses. In this review article, we summarize the recent contributions of microglia and astrocytes to the neurological impairments caused by viral infections. By expanding knowledge in this area, therapeutic approaches targeting immunological pathways may reduce the incidence of neurological and neurodegenerative disorders and increase the therapeutic window for neural protection.

Chemosensory Ability and Sensitivity in Health and Disease: Epigenetic Regulation and COVID-19

Throughout the animal kingdom, our two chemical senses, olfaction and gustation, are defined by two primary factors: genomic architecture of the organisms and their living environment. During the past three years of the global COVID-19 pandemic, these two sensory modalities have drawn much attention at the basic science and clinical levels because of the strong association of olfactory and gustatory dysfunction with viral infection. Loss of our sense of smell alone, or together with a loss of taste, has emerged as a reliable indicator of COVID-19 infection. Previously, similar dysfunctions have been detected in a large cohort of patients with chronic conditions. The research focus remains on understanding the persistence of olfactory and gustatory disturbances in the post-infection phase, especially in cases with long-term effect of infection (long COVID). Also, both sensory modalities show consistent age-related decline in studies aimed to understand the pathology of neurodegenerative conditions. Some studies using classical model organisms show an impact on neural structure and behavior in offspring as an outcome of parental olfactory experience. The methylation status of specific odorant receptors, activated in parents, is passed on to the offspring. Furthermore, experimental evidence indicates an inverse correlation of gustatory and olfactory abilities with obesity. Such diverse lines of evidence emerging from basic and clinical research studies indicate a complex interplay of genetic factors, evolutionary forces, and epigenetic alterations. Environmental factors that regulate gustation and olfaction could induce epigenetic modulation. However, in turn, such modulation leads to variable effects depending on genetic makeup and physiological status. Therefore, a layered regulatory hierarchy remains active and is passed on to multiple generations. In the present review, we attempt to understand the experimental evidence that indicates variable regulatory mechanisms through multilayered and cross-reacting pathways. Our analytical approach will add to enhancement of prevailing therapeutic interventions and bring to the forefront the significance of chemosensory modalities for the evaluation and maintenance of long-term health.

COVID-19: A trigger of autoimmune diseases

The SARS-coronavirus-2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19), has spread worldwide and caused a global health emergency. SARS-CoV-2 is a coronaviridae virus that infects target cells by interacting with the plasma membrane-expressed angiotensin-converting enzyme 2 (ACE2) via the S1 component of the S protein. Effective host immune response to SARS-CoV-2 infection, which includes both innate and adaptive immunity, is critical for virus management and elimination. The intensity and outcome of COVID-19 may be related to an overabundance of pro-inflammatory cytokines, which results in a "cytokine storm" and acute respiratory distress syndrome. After SARS-CoV-2 infection, the immune system's hyperactivity and production of autoantibodies may result in autoimmune diseases such as autoimmune hemolytic anemia, autoimmune thrombocytopenia, Guillain-Barré syndrome, vasculitis, multiple sclerosis, pro-thrombotic state, and diffuse coagulopathy, as well as certain autoinflammatory conditions such as Kawasaki disease in children. We have reviewed the association between COVID-19 and autoimmune disorders in this article.

Appearance of extrapyramidal symptoms in adolescent psychiatry patients during COVID-19 infection

Since the start of the pandemic, there has been an increase in the incidence of psychiatric morbidity among those infected with coronavirus disease 2019 (COVID-19) and those indirectly affected by COVID-19. There has been a considerable increase in the number of individuals with such psychiatric conditions as depression, acute stress disorders, anxiety, and posttraumatic stress disorder (PTSD). About one-third of patients with COVID-19 are reported to have developed short and long-term neuropsychiatric conditions such as delirium, agitation, altered consciousness, hypoxic encephalopathy encephalitis, dysexecutive syndrome, cerebrovascular complications (e.g., stroke), hypoxic encephalopathy, convulsions, neuromuscular dysfunction, demyelinating processes, or parkinsonism through several pathophysiological mechanisms. Nevertheless, as the pandemic progressed, data on neuropsychiatric manifestations implied that the pathologic capacity of COVID-19 and its association with the onset and/or exacerbation of psychiatric morbidity indicate that COVID-19 is potentially related to neuropsychiatric involvement. Patients with existing mental disorders under psychotropic treatment exposed to the COVID-19 infection have been represented by an increased risk of worsened psychiatric symptoms and expanded drug side effects. The present study aimed to describe five pediatric patients with various psychiatric illness that experienced COVID-19 infection and had potentially associated neuropsychiatric involvement, such as exacerbation of underlying psychiatric symptoms and extrapyramidal side effects. To the best of our knowledge, the present study is the first to describe adolescents with COVID-19 infection that presented with a series of manifestations in the form of an increase in extrapyramidal symptoms (EPS)  during exacerbation of underlying psychiatric disease.

Full protection from SARS-CoV-2 brain infection and damage in susceptible transgenic mice conferred by MVA-CoV2-S vaccine candidate

Vaccines against SARS-CoV-2 have been shown to be safe and effective but their protective efficacy against infection in the brain is yet unclear. Here, in the susceptible transgenic K18-hACE2 mouse model of severe coronavirus disease 2019 (COVID-19), we report a spatiotemporal description of SARS-CoV-2 infection and replication through the brain. SARS-CoV-2 brain replication occurs primarily in neurons, leading to neuronal loss, signs of glial activation and vascular damage in mice infected with SARS-CoV-2. One or two doses of a modified vaccinia virus Ankara (MVA) vector expressing the SARS-CoV-2 spike (S) protein (MVA-CoV2-S) conferred full protection against SARS-CoV-2 cerebral infection, preventing virus replication in all areas of the brain and its associated damage. This protection was maintained even after SARS-CoV-2 reinfection. These findings further support the use of MVA-CoV2-S as a promising vaccine candidate against SARS-CoV-2/COVID-19.

Repeated ethanol exposure and withdrawal alters angiotensin-converting enzyme 2 expression in discrete brain regions: Implications for SARS-CoV-2 neuroinvasion

BACKGROUND

People with alcohol use disorder (AUD) may be at higher risk for COVID-19. Angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) are required for cellular entry by SARS-CoV-2, but information on their expression in specific brain regions after alcohol exposure is limited. We sought to clarify how chronic alcohol exposure affects ACE2 expression in monoaminergic brainstem circuits and other putative SARS-CoV-2 entry points.

METHODS

Brains were examined for ACE2 using immunofluorescence after 4 weeks of chronic intermittent ethanol (CIE) vapor inhalation. We also examined TMPRSS2, Cathepsin L, and ADAM17 by Western blot and RAS pathway mediators and pro-inflammatory markers via RT-qPCR.

RESULTS

ACE2 was increased in most brain regions following CIE including the olfactory bulb (OB), hypothalamus (HT), raphe magnus (RMG), raphe obscurus (ROB), locus coeruleus (LC), and periaqueductal gray (PAG). We also observed increased colocalization of ACE2 with monoaminergic neurons in brainstem nuclei. Moreover, soluble ACE2 (sACE2) was elevated in OB, HT, and LC. The increase in sACE2 in OB and HT was accompanied by upregulation of ADAM17, an ACE2 sheddase, while TMPRSS2 increased in HT and LC. Cathepsin L, an endosomal receptor involved in viral entry, was also increased in OB. Alcohol can increase Angiotensin II, which triggers a pro-inflammatory response that may upregulate ACE2 via activation of RAS pathway receptors AT1R/AT2R. ACE2 then metabolizes Angiotensin II to Angiotensin (1-7) and provokes an anti-inflammatory response via MAS1. Accordingly, we report that AT1R/AT2R mRNA decreased in OB and increased in the LC, while MAS1 mRNA increased in both OB and LC. Other mRNAs for pro-inflammatory markers were also dysregulated in OB, HT, raphe, and LC.

CONCLUSIONS

Our results suggest that alcohol triggers a compensatory upregulation of ACE2 in the brain due to disturbed RAS and may increase the risk or severity of SARS-CoV-2 infection.

Pathogenesis and progression of anosmia and dysgeusia during the COVID-19 pandemic

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is the causative agent of COVID-19 which was detected in late 2019 in Wuhan, China. As of September 2022, there have been over 612 million confirmed cases of COVID-19 with over 6.5 million associated deaths. In many cases, anosmia and dysgeusia have been identified as primary symptoms of COVID-19 infection in patients. While the loss of smell (anosmia) and loss of taste (dysgeusia) due to COVID-19 infection is transient in most patients, many report that these symptoms persist following recovery. Understanding the pathogenesis of these symptoms is paramount to early treatment of the infection. We conducted a literature review of Google Scholar and PubMed to find and analyze studies discussing anosmia and dysgeusia in the context of COVID-19 to understand the progression and management of these symptoms. The mechanism for dysgeusia is largely unknown; however, pathogenesis of anosmia includes inflammation and cytokine release resulting from the infection that alters neuronal signaling, thus inducing the loss of smell that patients experience. Anosmia may be managed and potentially resolved sooner with a combination therapy of olfactory training and budesonide irrigation of the nasal cavity. It is important to note that the variants of SARS-CoV-2 are genetically distinguished from the original virion due to a mutation in their spike proteins, giving them a different symptom profile regarding anosmia and dysgeusia. This variability in symptomatology is an area of study that needs to be further explored.

Human ACE-2, MCP1 and micro-RNA 146 as Novel Markers for COVID- 19 Affection and Severity

BACKGROUND & AIMS

Coronavirus disease - 2019 (COVID-19) is a major pandemic that causes high morbidity and mortality rates.

AIM OF THIS STUDY

to detect the relations between many risk factors, ACE-2, MCP-1, Micro RNA 146 gene expression, and COVID-19 infection and disease severity.

METHODS

This study was carried out on 165 cases of COVID-19 and 138 controls. ACE2 and MCP1 levels were measured in COVID-19 cases and control by ELISA and micro-RNA-146 expression by PCR.

RESULTS

We found an increased blood level of ACE2 and MCP1 in COVID- 19 patients than in healthy persons and a significant down-regulation of micro-RNA 146 gene expression in cases than in controls. There was a significant correlation between increased blood level of ACE2, regulation of micro-RNA 146 gene expression and severity of lung affection, a significant correlation was found between increased blood level of MCP1 and thrombosis in COVID-19 patients. Neurological complications were significantly correlated with more viral load, more ACE2 blood level, and down regulation of micro RNA146 expression.

CONCLUSION

High viral load, increased blood level of ACE2, and down-regulation of micro-RNA 146 expression are associated with more severe lung injury and the presence of neurologic complications like convulsions and coma in COVID-19 Egyptian patients.

Mechanistic Insight and Possible Mechanism of Seizure in Covid-19: The Nuances and Focal Points

Coronavirus disease 2019 (COVID-19) is a primary respiratory disease with an alarming impact worldwide. COVID-19 is caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) and presents various neurological symptoms, including seizures. SARS-CoV-2 shows neuroinvasive and neurotropic capabilities through a neuronal angiotensin-converting enzyme 2 (ACE2), which is also highly expressed in both neuronal and glial cells. Therefore, SARS-CoV-2 can trigger neuroinflammation and neuronal hyperexcitability, increasing the risk of seizures. Olfactory neurons could be an exceptional neuronal pathway for the neuroinvasion of respiratory viruses to access the central nervous system (CNS) from the nasal cavity, leading to neuronal injury and neuroinflammation. Although neuronal ACE2 has been widely studied, other receptors for SARS-CoV-2 in the brain have been proposed to mediate viral-neuronal interactions with subsequent neurological squeals. Thus, the objective of the present critical review was to find the association and mechanistic insight between COVID-19 and the risk of seizures.

COVID-19 (novel SARS-CoV-2) neurological illness

COVID-19 illness is associated with diverse neurological manifestations. Its exceptionally high prevalence results from unprecedented genetic diversity, genomic recombination, and superspreading. With each new mutation and variant, there are foreseeable risks of rising fatality and novel neurological motor complications in childhood and adult cases. This chapter provides an extensive review of COVID-19 neurological illness, notably the motor manifestations. Innovative treatments have been developed to stem the spread of infectious contagious illness, and attenuate the resultant cytokine storm and other postinfectious immune aspects responsible for postacute COVID-19 syndrome due to the multiplier effect of infection, immunity, and inflammation, termed I3.

Neurological manifestations of SARS-CoV-2 infections: towards quantum dots based management approaches

Developing numerous nanotechnological designed tools to monitor the existence of SARS-CoV-2, and modifying its interactions address the global needs for efficient remedies required for the management of COVID-19. Herein, through a multidisciplinary outlook encompassing different fields such as the pathophysiology of SARS-CoV-2, analysis of symptoms, and statistics of neurological complications caused by SARS-CoV-2 infection in the central and peripheral nervous systems have been testified. The anosmia (51.1%) and ageusia (45.5%) are reported the most frequent neurological manifestation. Cerebrovascular disease and encephalopathy were mainly related to severe clinical cases. In addition, we focus especially on the various concerned physiological routes, including BBB dysfunction, which transpired due to SARS-CoV-2 infection, direct and indirect effects of the virus on the brain, and also, the plausible mechanisms of viral entry to the nerve system. We also outline the characterisation, and the ongoing pharmaceutical applications of quantum dots as smart nanocarriers crossing the blood-brain barrier and their importance in neurological diseases, mainly SARS-CoV-2 related manifestations Moreover, the market status, six clinical trials recruiting quantum dots, and the challenges limiting the clinical application of QDs are highlighted.

Delayed onset of fatal encephalitis in a COVID-19 positive patient

BACKGROUND

The SARS-nCoV-2019 epidemic has spread since December 2019, quickly gaining worldwide attention. Symptoms consist of fever, cough and breathing difficulties. An increasing number of studies are focusing on neurological manifestations. In addition to the typical ageusia and anosmia, up to 30% of cases can present headache, nausea and vomiting. More serious neurological manifestations, such as encephalitis, thrombosis and cerebral haemorrhage have been reported.

CASE DESCRIPTION

We described the case of a 47-year-old man who tested positive for COVID-19 virus in early March 2020. After two negative nasopharyngeal swabs, 41 days after the diagnosis of COVID-19 infection, he developed intense headache with fever, and he was hospitalized. He had subsequent generalized epileptic seizures and intubation was necessary. Contrast Head MRI was negative for brain abscesses or tumours but detected severe vasogenic oedema of the white matter with 10 mm shift of the midline and compression of the right lateral ventricle. Massive cortisone support therapy was ineffective. We diagnosed brain death on day 43 from the infection diagnosis.

DISCUSSION

COVID-19 virus can reach the brain, penetrating into the neuronal cells through the interaction between the spike protein S1 and the host ACE-2 receptor, expressed in the capillary endothelium. We believe that in this infection, the pro-inflammatory state induced by the cytokine storm can cause a cerebral cell-mediated response, with subsequent vasodilatation and brain oedema.

CONCLUSION

To our knowledge, this is the first description of a delayed onset cell-mediated encephalitis caused by COVID-19 virus after more than 40 days from the diagnosis.

Exploring the research landscape of COVID-19-induced olfactory dysfunction: A bibliometric study

Since the outbreak of COVID-19, olfactory dysfunction (OD) has become an important and persistent legacy problem that seriously affects the quality of life. The purpose of this paper is to quantitatively analyze and visualize the current research status and development trend of COVID-19 related OD by using VOSviewer software. Based on the Web of Science database, a total of 1,592 relevant documents were retrieved in January 2023, with publication time spanning from 2020 to 2023. The bibliometric analysis revealed that the most influential research results in the field of COVID-19 related OD were concentrated in journals of related disciplines such as otorhinolaryngology, medicine, general and internal, virology, neurosciences, etc. The knowledge base of the research is mainly formed in two fields: COVID-19 clinical research and OD specialized research. The research hotspots are mainly concentrated in six directions: COVID-19, long COVID, smell, anosmia, OD, and recovery. Based on the results of the bibliometric analysis, the temporal trends of COVID-19 related OD studies were visually revealed, and relevant suggestions for future research were proposed.

Generation and Characterization of a SARS-CoV-2-Susceptible Mouse Model Using Adeno-Associated Virus (AAV6.2FF)-Mediated Respiratory Delivery of the Human ACE2 Gene

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the aetiological agent of coronavirus disease 2019 (COVID-19) that has caused a pandemic with millions of human infections. There continues to be a pressing need to develop potential therapies and vaccines to inhibit SARS-CoV-2 infection to mitigate the ongoing pandemic. Epidemiological data from the current pandemic indicates that there may be sex-dependent differences in disease outcomes. To investigate these differences, we proposed to use common small animal species that are frequently used to model disease with viruses. However, common laboratory strains of mice are not readily infected by SARS-CoV-2 because of differences in the angiotensin-converting enzyme 2 (ACE2), the cellular receptor for the virus. To overcome this limitation, we transduced common laboratory accessible strains of mice of different sexes and age groups with a novel a triple AAV6 mutant, termed AAV6.2FF, encoding either human ACE2 or luciferase via intranasal administration to promote expression in the lung and nasal turbinates. Infection of AAV-hACE2-transduced mice with SARS-CoV-2 resulted in high viral titers in the lungs and nasal turbinates, establishment of an IgM and IgG antibody response, and modulation of lung and nasal turbinate cytokine profiles. There were insignificant differences in infection characteristics between age groups and sex-related differences; however, there were significant strain-related differences between BALB/c vs. C57BL/6 mice. We show that AAV-hACE2-transduced mice are a useful for determining immune responses and for potential evaluation of SARS-CoV-2 vaccines and antiviral therapies, and this study serves as a model for the utility of this approach to rapidly develop small-animal models for emerging viruses.