Potential neuroinvasive pathways of SARS-CoV-2: Deciphering the spectrum of neurological deficit seen in coronavirus disease-2019 (COVID-19)

Persistent dysfunctions of brain metabolic connectivity in long-covid with cognitive symptoms

PURPOSE

Our study examines brain metabolic connectivity in SARS-CoV-2 survivors during the acute-subacute and chronic phases, aiming to elucidate the mechanisms underlying the persistence of neurological symptoms in long-COVID patients.

METHODS

We perfomed a cross-sectional study including 44 patients (pts) with neurological symptoms who underwent FDG-PET scans, and classified to timing infection as follows: acute (7 pts), subacute (17 pts), long-term (20 pts) phases. Interregional correlation analysis (IRCA) and ROI-based IRCA were applied on FDG-PET data to extract metabolic connectivity in resting state networks (ADMN, PDMN, EXN, ATTN, LIN, ASN) of neuro-COVID pts in acute/subacute and long-term groups compared with healthy controls (HCs). Univariate approach was used to investigate metabolic alterations from the acute to sub-acute and long-term phase.

RESULTS

The acute/subacute phase was characterized by hyperconnectivity in EXN and ATTN networks; the same networks showed hypoconnectivity in the chronic phase. EXN and ATTN hypoconnectivity was consistent with clinical findings in long-COVID patients, e.g. altered performances in neuropsychological tests of executive and attention domains. The ASN and LIN presented hyperconnectivity in acute/subacute phase and normalized in long-term phase. The ADMN and PDMN presented a preseverved connectivity. Univariate analysis showed hypometabolism in fronto-insular cortex in acute phase, which reduced in sub-acute phase and disappeared in long-term phase.

CONCLUSION

A compensatory EXN and ATTN hyperconnectivity was found in the acute/subacute phase and hypoconnectivity in long-term. Hypoconnectivity and absence of hypometabolism suggest that connectivity derangement in frontal networks could be related to protraction of neurological symptoms in long-term COVID patients.

COVID-19 related cognitive, structural and functional brain changes among Italian adolescents and young adults: a multimodal longitudinal case-control study

Coronavirus disease 2019 (COVID-19) has been associated with brain functional, structural, and cognitive changes that persist months after infection. Most studies of the neurologic outcomes related to COVID-19 focus on severe infection and aging populations. Here, we investigated the neural activities underlying COVID-19 related outcomes in a case-control study of mildly infected youth enrolled in a longitudinal study in Lombardy, Italy, a global hotspot of COVID-19. All participants (13 cases, 27 controls, mean age 24 years) completed resting-state functional (fMRI), structural MRI, cognitive assessments (CANTAB spatial working memory) at baseline (pre-COVID) and follow-up (post-COVID). Using graph theory eigenvector centrality (EC) and data-driven statistical methods, we examined differences in ECdelta (i.e., the difference in EC values pre- and post-COVID-19) and Volumetricdelta (i.e., the difference in cortical volume of cortical and subcortical areas pre- and post-COVID) between COVID-19 cases and controls. We found that ECdelta significantly between COVID-19 and healthy participants in five brain regions; right intracalcarine cortex, right lingual gyrus, left hippocampus, left amygdala, left frontal orbital cortex. The left hippocampus showed a significant decrease in Volumetricdelta between groups (p = 0.041). The reduced ECdelta in the left amygdala associated with COVID-19 status mediated the association between COVID-19 and disrupted spatial working memory. Our results show persistent structural, functional and cognitive brain changes in key brain areas associated with olfaction and cognition. These results may guide treatment efforts to assess the longevity, reversibility and impact of the observed brain and cognitive changes following COVID-19.

Characterizing neuroinvasion and neuropathology of SARS-CoV-2 by using AC70 human ACE2 transgenic mice

COVID-19 presents with a plethora of neurological signs and symptoms despite being characterized as a respiratory disease, including seizures, anxiety, depression, amnesia, attention deficits, and alterations in consciousness. The olfactory nerve is widely accepted as the neuroinvasive route by which the etiological agent SARS-CoV-2 enters the brain, but the trigeminal nerve is an often-overlooked additional route. Based on this consensus, we initially conducted a pilot experiment investigating the olfactory nerve route of SARS-CoV-2 neuroinvasion via intranasal inoculation in AC70 human ACE2 transgenic mice. Notably, we found that the trigeminal ganglion is an early and highly efficient site of viral replication, which then rapidly spread widely throughout the brain where neurons were primarily targeted. Despite the extensive viral infection across the brain, obvious evidence of tissue pathology including inflammatory infiltration, glial activation, and apoptotic cell deaths were not consistently observed, albeit inflammatory cytokines were significantly induced. However, the expression levels of different genes related to neuronal function, including the neurotransmitter dopamine pathway as well as synaptic function, and markers of neuronal damage were altered as compared to mock-infected mice. Our findings suggest that the trigeminal nerve may serve as a neuroinvasive route complementary to the olfactory nerve and that the ensuing neuroinvasion presented a unique neuropathological profile. This study provides insights into potential neuropathogenic mechanisms utilized by coronaviruses.

Sustainable and technically smart spectrophotometric determination of PAXLOVID: a comprehensive ecological and analytical performance rating

The Food and Drug Administration (FDA) authorized the administration of ritonavir (RIT)-boosted nirmatrelvir (NMV) on May 25, 2023, for the treatment of mild to moderate COVID-19 in patients who are at high risk of developing severe COVID-19. In accordance with sustainability and environmental friendliness, simple, eco-friendly, and sustainable spectrophotometric methods were established for concurrently estimating RIT and NMV in newly launched copackaged pills. The suggested solutions for resolving the spectral overlap between RIT and NMV involve the following mathematical methods: the first derivative method (1D), second derivative method (2D), and dual-wavelength zero-order method (DWZ). When ethanol was used as a green dilution solvent, the linearity range was adjusted (10-250 µg/mL) for both drugs. The procedures resulted in a high correlation coefficient (not less than 0.9996) and satisfactory levels of detection and quantification. Additionally, method validation was performed in accordance with International Council for Harmonization norms. Moreover, a detailed ecological and sustainability evaluation protocol was established to confirm the greenness and whiteness of the methods. Finally, the proposed method, along with previously reported methods for analysing NMV and RIT, were reviewed analytically and ecologically.

Angiotensin-Converting Enzyme-2 (ACE2) Downregulation During Coronavirus Infection

Angiotensin-converting enzyme-2 (ACE2) downregulation represents a detrimental factor in people with a baseline ACE2 deficiency associated with older age, hypertension, diabetes, and cardiovascular diseases. Human coronaviruses, including HCoV-NL63, SARS-CoV-1, and SARS CoV-2 infect target cells via binding of viral spike (S) glycoprotein to the ACE2, resulting in ACE2 downregulation through yet unidentified mechanisms. This downregulation disrupts the enzymatic activity of ACE2, essential in protecting against organ injury by cleaving and disposing of Angiotensin-II (Ang II), leading to the formation of Ang 1-7, thereby exacerbating the accumulation of Ang II. This accumulation activates the Angiotensin II type 1 receptor (AT1R) receptor, leading to leukocyte recruitment and increased proinflammatory cytokines, contributing to organ injury. The biological impacts and underlying mechanisms of ACE2 downregulation during SARS-CoV-2 infection have not been well defined. Therefore, there is an urgent need to establish a solid theoretical and experimental understanding of the mechanisms of ACE2 downregulation during SARS-CoV-2 entry and replication in the host cells. This review aims to discuss the physiological impact of ACE2 downregulation during coronavirus infection, the relationship between ACE2 decline and virus pathogenicity, and the possible mechanisms of ACE2 degradation, along with the therapeutic approaches.

Causal effect of COVID-19 on optic nerve and visual pathway disorders: genetic evidence of lung-brain axis

Purpose

To investigate the potential causal association between COVID-19 exposure and optic nerve and visual pathway disorders through a two-sample bidirectional Mendelian randomization (MR) analysis, and to provide empirical support for the lung-brain axis.

Methods

This MR analysis utilized publicly accessible summary-level data from genome-wide association studies on COVID-19 (n=158,783) and optic nerve and visual pathway diseases (n=412,181), primarily involving individuals of European descent. The random-effect inverse-variance weighted estimation was applied as the main analytical approach, complemented by MR-Egger, weighted median, and weighted mode methods. The heterogeneity and pleiotropy of the instrumental variables were assessed using Cochran's Q test, leave-one-out sensitivity analysis, MR-Egger intercept test, MR-PRESSO, and funnel plot evaluations.

Results

In the forward analysis, the inverse-variance weighted method identified a significant causal effect of COVID-19 on optic nerve and visual pathway disorders (odds ratio = 1.697, 95% confidence interval: 1.086-2.652, p = 0.020). Directionally consistent results were also observed with MR-Egger regression, weighted median, and weighted mode approaches. Conversely, the reverse analysis revealed no causal effects of optic nerve and visual pathway disorders on COVID-19 susceptibility.

Conclusion

Our findings suggest that COVID-19 exposure may increase the risk of developing optic nerve and visual pathway disorders, supporting the lung-brain axis hypothesis. These results underscore the importance of vigilant monitoring of the visual system in patients recovering from COVID-19 and suggest potential avenues for future therapeutic strategies.

[Dizziness and hearing loss in healthcare workers with COVID-19]

Coronavirus disease 2019 (COVID-19) affects the respiratory system. Studying the clinical characteristics of this infection has revealed its tropism to the nervous system, which is responsible for neurological and sensory damage, in particular, dizziness and hearing loss. To determine the frequency and characteristics of the neurological impairment represented by dizziness and hearing loss in healthcare professionals (HCP) with COVID-19. Cross-sectional descriptive study conducted among HCP at Charles Nicolle Hospital (CNH) in Tunis affected by COVID-19 during the period from September 2020 to December 2020. Data collection was carried out by regular telephone follow-up of COVID-19 symptoms in these HCPs during the period of sanitary isolation. A total of 482 HCPs with COVID-19 were collected. The average age of the population was 41 ± 10 years, of which 111 were men (23%) and 371 were women (77%). The main neurological manifestations were: headache (71.2%), anosmia (60%), dizziness (21.8%), and hearing loss (1.5%). Patients with vertigo were significantly older (P=0.035), female (P=0.003), obese (P=0.014), suffering from more comorbidities (P=0.004), and having greater professional seniority (P=0.009). Dizziness was significantly associated with fever (P=0.001), abdominal pain (P=0.001), and desaturation (P=0.039). Neurological symptoms including dizziness and hearing loss may be the only sign with which a case of COVID-19 could be recognized. Raising awareness of such a presentation of COVID-19 patients is crucial during this pandemic period to prevent infectious spread, especially in hospitals.

Square the Circle: Diversity of Viral Pathogens Causing Neuro-Infectious Diseases

Neuroinfections rank among the top ten leading causes of child mortality globally, even in high-income countries. The crucial determinants for successful treatment lie in the timing and swiftness of diagnosis. Although viruses constitute the majority of infectious neuropathologies, diagnosing and treating viral neuroinfections remains challenging. Despite technological advancements, the etiology of the disease remains undetermined in over half of cases. The identification of the pathogen becomes more difficult when the infection is caused by atypical pathogens or multiple pathogens simultaneously. Furthermore, the modern surge in global passenger traffic has led to an increase in cases of infections caused by pathogens not endemic to local areas. This review aims to systematize and summarize information on neuroinvasive viral pathogens, encompassing their geographic distribution and transmission routes. Emphasis is placed on rare pathogens and cases involving atypical pathogens, aiming to offer a comprehensive and structured catalog of viral agents with neurovirulence potential.

Optic Neuritis in Resolving Phase of COVID-19 Infection and Its Management: A Case Report

Optic neuritis is assumed to be immune-mediated, although the specific antigens that cause demyelination are uncertain. Systemic T-cell activation is detected at the onset of symptoms, which occurs before alterations in cerebrospinal fluid (CSF). The optic nerve disease is a rare disease and can occur in one or both eyes, especially in those with no established inflammatory or autoimmune illnesses. Adult ophthalmic neuritis is usually unilateral and is frequently associated with multiple sclerosis (MS). Generally, it starts as a rapid loss of vision and pain in eye movement. It progresses and achieves the maximal deficiency over a week. The objectives of this paper were to determine the association between coronavirus disease 2019 (COVID-19) and optic neuritis and to study the management of optic neuritis in the resolving phase of COVID-19. A case study was done on a 38-year-old female complaining of sudden diminution of vision in her right eye for one week. She tested positive on the reverse transcriptase-polymerase chain reaction (RT-PCR) test for COVID-19 for which she was managed symptomatically and was started on antiretrovirals. This case report is based on an infrequent COVID-19 complication. It has been proposed that this virus has the probability of manifesting various neurological complications. In our case, optic neuritis occurs mainly three weeks after COVID-19 infection. Our patient was managed by intravenous methylprednisolone injection followed by oral prednisone for 14 days. So, further case studies will be required to support the above treatment plan for optic neuritis caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Unilateral or bilateral optic neuritis can occur as a neurological complication in the resolving stage of COVID-19 infection. Early detection and treatment with steroids can result in the best visual outcome.

Utility of sustainable ratio derivative spectrophotometry for the concurrent assay of synergistic repurposed drugs for COVID-19 infections; Insilico pharmacokinetics proof

The cutting-edge combination of fluvoxamine (FVM) and ivermectin (IVM) has been presented as a proposed dosage form for the treatment of COVID-19 infections in early diagnosed patients. The main objective of this work is to develop simple, sensitive, and efficient methods for the synchronous quantification of FVM and IVM without any prior separation. Four green UV-methods were employed for the synchronous quantification, namely: Fourier functions convolution of absorption spectra, FFAS, Fourier functions convolution of derivative spectra of absorption curves, FFDS, Fourier function convolution of ratio spectra of absorption curves, FFRS and the dual-wavelength method, DWM. FFRS and DWM approaches can be able to reconcile the two components' significantly interfering spectrum presented in this commixture. Good linearity was checked in the range of 5-40, and 2.5-25 μg/mL for the FVM, and IVM, respectively. All approaches developed have been recommended in compliance with ICH principles. Furthermore, the approaches' greenness was predestined by "National Environmental Method Index" (NEMI), "Analytical GREEnness metric (AGREE)", the "Analytical Eco-Scale", and the "Green Analytical Procedure Index" (GAPI). In addition, spider diagram was utilized for the assessment of the greenness index of the solvent used. Beside greenness, the sustainability of our methods was investigated using the HEXAGON tool. Continuing the constant pursuit of greenness, drug-drug interactions (DDIs) between FVM & IVM were predicted by insilico tools to ensure the safety of the suggested mixture as a preliminary step before invitro and in vivo studies. Because they were deemed sustainable, affordable, and successful, the suggested UV-methods may be used for routine quality control investigations of the indicated formulations FVM & IVM.

Extracellular Vesicles: The Invisible Heroes and Villains of COVID-19 Central Neuropathology

Acknowledging the neurological symptoms of COVID-19 and the long-lasting neurological damage even after the epidemic ends are common, necessitating ongoing vigilance. Initial investigations suggest that extracellular vesicles (EVs), which assist in the evasion of the host's immune response and achieve immune evasion in SARS-CoV-2 systemic spreading, contribute to the virus's attack on the central nervous system (CNS). The pro-inflammatory, pro-coagulant, and immunomodulatory properties of EVs contents may directly drive neuroinflammation and cerebral thrombosis in COVID-19. Additionally, EVs have attracted attention as potential candidates for targeted therapy in COVID-19 due to their innate homing properties, low immunogenicity, and ability to cross the blood-brain barrier (BBB) freely. Mesenchymal stromal/stem cell (MSCs) secreted EVs are widely applied and evaluated in patients with COVID-19 for their therapeutic effect, considering the limited antiviral treatment. This review summarizes the involvement of EVs in COVID-19 neuropathology as carriers of SARS-CoV-2 or other pathogenic contents, as predictors of COVID-19 neuropathology by transporting brain-derived substances, and as therapeutic agents by delivering biotherapeutic substances or drugs. Understanding the diverse roles of EVs in the neuropathological aspects of COVID-19 provides a comprehensive framework for developing, treating, and preventing central neuropathology and the severe consequences associated with the disease.

COVID-19 and Mental Health: A "Pandemic Within a Pandemic"

The COVID-19 pandemic has brought significant changes in daily life for humanity and has had a profound impact on mental health. As widely acknowledged, the pandemic has led to notable increases in rates of anxiety, depression, distress, and other mental health-related issues, affecting both infected patients and non-infected individuals. COVID-19 patients and survivors face heightened risks for various neurological and psychiatric disorders and complications. Vulnerable populations, including those with pre-existing mental health conditions and individuals living in poverty or frailty, may encounter additional challenges. Tragically, suicide rates have also risen, particularly among young people, due to factors such as unemployment, financial crises, domestic violence, substance abuse, and social isolation. Efforts are underway to address these mental health issues, with healthcare professionals urged to regularly screen both COVID-19 and post-COVID-19 patients and survivors for psychological distress, ensuring rapid and appropriate interventions. Ongoing periodic follow-up and multidimensional, interdisciplinary approaches are essential for individuals experiencing long-term psychiatric sequelae. Preventive strategies must be developed to mitigate mental health problems during both the acute and recovery phases of COVID-19 infection. Vaccination efforts continue to prioritize vulnerable populations, including those with mental health conditions, to prevent future complications. Given the profound implications of mental health problems, including shorter life expectancy, diminished quality of life, heightened distress among caregivers, and substantial economic burden, it is imperative that political and health authorities prioritize the mental well-being of all individuals affected by COVID-19, including infected individuals, non-infected individuals, survivors, and caregivers.

Probing long COVID through a proteomic lens: a comprehensive two-year longitudinal cohort study of hospitalised survivors

BACKGROUND

As a debilitating condition that can impact a whole spectrum of people and involve multi-organ systems, long COVID has aroused the most attention than ever. However, mechanisms of long COVID are not clearly understood, and underlying biomarkers that can affect the long-term consequences of COVID-19 are paramount to be identified.

METHODS

Participants for the current study were from a cohort study of COVID-19 survivors discharged from hospital between Jan 7, and May 29, 2020. We profiled the proteomic of plasma samples from hospitalised COVID-19 survivors at 6-month, 1-year, and 2-year after symptom onset and age and sex matched healthy controls. Fold-change of >2 or <0.5, and false-discovery rate adjusted P value of 0.05 were used to filter differentially expressed proteins (DEPs). In-genuity pathway analysis was performed to explore the down-stream effects in the dataset of significantly up- or down-regulated proteins. Proteins were integrated with long-term consequences of COVID-19 survivors to explore potential biomarkers of long COVID.

FINDINGS

The proteomic of 709 plasma samples from 181 COVID-19 survivors and 181 matched healthy controls was profiled. In both COVID-19 and control group, 114 (63%) were male. The results indicated four major recovery modes of biological processes. Pathways related to cell-matrix interactions and cytoskeletal remodeling and hypertrophic cardiomyopathy and dilated cardiomyopathy pathways recovered relatively earlier which was before 1-year after infection. Majority of immune response pathways, complement and coagulation cascade, and cholesterol metabolism returned to similar status of matched healthy controls later but before 2-year after infection. Fc receptor signaling pathway still did not return to status similar to healthy controls at 2-year follow-up. Pathways related to neuron generation and differentiation showed persistent suppression across 2-year after infection. Among 98 DEPs from the above pathways, evidence was found for association of 11 proteins with lung function recovery, with the associations consistent at two consecutive or all three follow-ups. These proteins were mainly enriched in complement and coagulation (COMP, PLG, SERPINE1, SRGN, COL1A1, FLNA, and APOE) and hypertrophic/dilated cardiomyopathy (TPM2, TPM1, and AGT) pathways. Two DEPs (APOA4 and LRP1) involved in both neuron and cholesterol pathways showed associations with smell disorder.

INTERPRETATION

The study findings provided molecular insights into potential mechanism of long COVID, and put forward biomarkers for more precise intervention to reduce burden of long COVID.

FUNDING

National Natural Science Foundation of China; Chinese Academy of Medical Sciences (CAMS) Innovation Fund for Medical Sciences; Clinical Research Operating Fund of Central High Level Hospitals; the Talent Program of the Chinese Academy of Medical Science; Training Program of the Big Science Strategy Plan; Ministry of Science and Technology of the People's Republic of China; New Cornerstone Science Foundation; Peking Union Medical College Education Foundation; Research Funds from Health@InnoHK Program.

Brain MRI findings in neurologically symptomatic COVID-19 patients: a systematic review and meta-analysis

BACKGROUND

Coronavirus disease 2019 (COVID-19) has been associated with nervous system involvement, with more than one-third of COVID-19 patients experiencing neurological manifestations. Utilizing a systematic review, this study aims to summarize brain MRI findings in COVID-19 patients presenting with neurological symptoms.

METHODS

Systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) checklist. The electronic databases of PubMed/MEDLINE, Embase, Scopus, and Web of Science were systematically searched for literature addressing brain MRI findings in COVID-19 patients with neurological symptoms.

RESULTS

25 publications containing a total number of 3118 COVID-19 patients with neurological symptoms who underwent MRI were included. The most common MRI findings and the respective pooled incidences in decreasing order were acute/subacute infarct (22%), olfactory bulb abnormalities (22%), white matter abnormalities (20%), cerebral microbleeds (17%), grey matter abnormalities (12%), leptomeningeal enhancement (10%), ADEM (Acute Disseminated Encephalomyelitis) or ADEM-like lesions (10%), non-traumatic ICH (10%), cranial neuropathy (8%), cortical gray matter signal changes compatible with encephalitis (8%), basal ganglia abnormalities (5%), PRES (Posterior Reversible Encephalopathy Syndrome) (3%), hypoxic-ischemic lesions (4%), venous thrombosis (2%), and cytotoxic lesions of the corpus callosum (2%).

CONCLUSION

The present study revealed that a considerable proportion of patients with COVID-19 might harbor neurological abnormalities detectable by MRI. Among various findings, the most common MRI alterations are acute/subacute infarction, olfactory bulb abnormalities, white matter abnormalities, and cerebral microbleeds.

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.

SARS-CoV-2-associated organs failure and inflammation: a focus on the role of cellular and viral microRNAs

SARS-CoV-2 has been responsible for the recent pandemic all over the world, which has caused many complications. One of the hallmarks of SARS-CoV-2 infection is an induced immune dysregulation, in some cases resulting in cytokine storm syndrome, acute respiratory distress syndrome and many organs such as lungs, brain, and heart that are affected during the SARS-CoV-2 infection. Several physiological parameters are altered as a result of infection and cytokine storm. Among them, microRNAs (miRNAs) might reflect this poor condition since they play a significant role in immune cellular performance including inflammatory responses. Both host and viral-encoded miRNAs are crucial for the successful infection of SARS-CoV-2. For instance, dysregulation of miRNAs that modulate multiple genes expressed in COVID-19 patients with comorbidities (e.g., type 2 diabetes, and cerebrovascular disorders) could affect the severity of the disease. Therefore, altered expression levels of circulating miRNAs might be helpful to diagnose this illness and forecast whether a COVID-19 patient could develop a severe state of the disease. Moreover, a number of miRNAs could inhibit the expression of proteins, such as ACE2, TMPRSS2, spike, and Nsp12, involved in the life cycle of SARS-CoV-2. Accordingly, miRNAs represent potential biomarkers and therapeutic targets for this devastating viral disease. In the current study, we investigated modifications in miRNA expression and their influence on COVID-19 disease recovery, which may be employed as a therapy strategy to minimize COVID-19-related disorders.

Covid-19 related cognitive, structural and functional brain changes among Italian adolescents and young adults: a multimodal longitudinal case-control study

Coronavirus disease 2019 (COVID-19) has been associated with brain functional, structural, and cognitive changes that persist months after infection. Most studies of the neurologic outcomes related to COVID-19 focus on severe infection and aging populations. Here, we investigated the neural activities underlying COVID-19 related outcomes in a case-control study of mildly infected youth enrolled in a longitudinal study in Lombardy, Italy, a global hotspot of COVID-19. All participants (13 cases, 27 controls, mean age 24 years) completed resting state functional (fMRI), structural MRI, cognitive assessments (CANTAB spatial working memory) at baseline (pre-COVID) and follow-up (post-COVID). Using graph theory eigenvector centrality (EC) and data-driven statistical methods, we examined differences in ECdelta (i.e., the difference in EC values pre- and post-COVID-19) and volumetricdelta (i.e., the difference in cortical volume of cortical and subcortical areas pre- and post-COVID) between COVID-19 cases and controls. We found that ECdeltasignificantly between COVID-19 and healthy participants in five brain regions; right intracalcarine cortex, right lingual gyrus, left hippocampus, left amygdala, left frontal orbital cortex. The left hippocampus showed a significant decrease in volumetricdelta between groups (p=0.041). The reduced ECdelta in the right amygdala associated with COVID-19 status mediated the association between COVID-19 and disrupted spatial working memory. Our results show persistent structural, functional and cognitive brain changes in key brain areas associated with olfaction and cognition. These results may guide treatment efforts to assess the longevity, reversibility and impact of the observed brain and cognitive changes following COVID-19.

Pre-existing T Cell Memory to Novel Pathogens

Immunological experiences lead to the development of specific T and B cell memory, which readies the host for a later pathogen rechallenge. Currently, immunological memory is best understood as a linear process whereby memory responses are generated by and directed against the same pathogen. However, numerous studies have identified memory cells that target pathogens in unexposed individuals. How "pre-existing memory" forms and impacts the outcome of infection remains unclear. In this review, we discuss differences in the composition of baseline T cell repertoire in mice and humans, factors that influence pre-existing immune states, and recent literature on their functional significance. We summarize current knowledge on the roles of pre-existing T cells in homeostasis and perturbation and their impacts on health and disease.

Association of Molnupiravir and Nirmatrelvir-Ritonavir with reduced mortality and sepsis in hospitalized omicron patients: a territory-wide study

This study evaluates the association between antivirals (Molnupiravir and Nirmatrelvir-Ritonavir) and all-cause and respiratory mortality and organ dysfunction among high-risk COVID-19 patients during an Omicron outbreak. Two cohorts, Nirmatrelvir-Ritonavir versus control and Molnupiravir versus control, were constructed with inverse probability treatment weighting to balance baseline characteristics. Cox proportional hazards models evaluated the association of their use with all-cause mortality, respiratory mortality, and all-cause sepsis (a composite of circulatory shock, respiratory failure, acute liver injury, coagulopathy, and acute liver impairment). Patients recruited were hospitalized and diagnosed with the COVID-19 Omicron variant between February 22, 2022 and April 15, 2022, and followed up until May 15, 2022. The study included 17,704 patients. There were 4.67 and 22.7 total mortalities per 1000 person-days in the Nirmatrelvir-Ritonavir and control groups respectively before adjustment (weighted incidence rate ratio, - 18.1 [95% CI - 23.0 to - 13.2]; hazard ratio, 0.18 [95% CI, 0.11-0.29]). There were 6.64 and 25.9 total mortalities per 1000 person-days in the Molnupiravir and control groups respectively before adjustment (weighted incidence rate ratio per 1000 person-days, - 19.3 [95% CI - 22.6 to - 15.9]; hazard ratio, 0.23 [95% CI 0.18-0.30]). In all-cause sepsis, there were 13.7 and 35.4 organ dysfunction events per 1000 person-days in the Nirmatrelvir-Ritonavir and control groups respectively before adjustment (weighted incidence rate ratio per 1000 person-days, - 21.7 [95% CI - 26.3 to - 17.1]; hazard ratio, 0.44 [95% CI 0.38-0.52]). There were 23.7 and 40.8 organ dysfunction events in the Molnupiravir and control groups respectively before adjustment (weighted incidence ratio per 1000 person-days, - 17.1 [95% CI, - 20.6 to - 13.6]; hazard ratio, 0.63 [95% CI 0.58-0.69]). Among COVID-19 hospitalized patients, use of either Nirmatrelvir-Ritonavir or Molnupiravir compared with no antiviral use was associated with a significantly lower incidence of 28-days all-cause and respiratory mortality and sepsis.

Olfactory dysfunction: A plausible source of COVID-19-induced neuropsychiatric symptoms

Olfactory dysfunction and neuropsychiatric symptoms are commonly reported by patients of coronavirus disease 2019 (COVID-19), a respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Evidence from recent research suggests linkages between altered or loss of smell and neuropsychiatric symptoms after infection with the coronavirus. Systemic inflammation and ischemic injury are believed to be the major cause of COVID-19-related CNS manifestation. Yet, some evidence suggest a neurotropic property of SARS-CoV-2. This mini-review article summarizes the neural correlates of olfaction and discusses the potential of trans-neuronal transmission of SARS-CoV-2 or its particles within the olfactory connections in the brain. The impact of the dysfunction in the olfactory network on the neuropsychiatric symptoms associated with COVID-19 will also be discussed.

Comparative transcriptomics reveals highly conserved regional programs between porcine and human colonic enteric nervous system

The porcine gut is increasingly regarded as a useful translational model. The enteric nervous system in the colon coordinates diverse functions. However, knowledge of the molecular profiling of porcine enteric nerve system and its similarity to that of human is still lacking. We identified the distinct transcriptional programs associated with functional characteristics between inner submucosal and myenteric ganglia in porcine proximal and distal colon using bulk RNA and single-cell RNA sequencing. Comparative transcriptomics of myenteric ganglia in corresponding colonic regions of pig and human revealed highly conserved programs in porcine proximal and distal colon, which explained >96% of their transcriptomic responses to vagal nerve stimulation, suggesting that porcine proximal and distal colon could serve as predictors in translational studies. The conserved programs specific for inflammatory modulation were displayed in pigs with vagal nerve stimulation. This study provides a valuable transcriptomic resource for understanding of human colonic functions and neuromodulation using porcine model.

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.

Neuromasts and Olfactory Organs of Zebrafish Larvae Represent Possible Sites of SARS-CoV-2 Pseudovirus Host Cell Entry

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the acute respiratory disease coronavirus disease 2019 (COVID-19), which has resulted in millions of deaths globally. Here, we explored the mechanism of host cell entry of a luciferase-ZsGreen spike (SARS-CoV-2)-pseudotyped lentivirus using zebrafish embryos/larvae as an in vivo model. Successful pseudovirus entry was demonstrated via the expression of the luciferase (luc) gene, which was validated by reverse transcription-PCR (RT-PCR). Treatment of larvae with chloroquine (a broad-spectrum viral inhibitor that blocks membrane fusion) or bafilomycin A1 (a specific inhibitor of vacuolar proton ATPases, which blocks endolysosomal trafficking) significantly reduced luc expression, indicating the possible involvement of the endolysosomal system in the viral entry mechanism. The pharmacological inhibition of two-pore channel (TPC) activity or use of the tpcn2^dhkz1a mutant zebrafish line also led to diminished luc expression. The localized expression of ACE2 and TPC2 in the anterior neuromasts and the forming olfactory organs was demonstrated, and the occurrence of endocytosis in both locations was confirmed. Together, our data indicate that zebrafish embryos/larvae are a viable and tractable model to explore the mechanism of SARS-CoV-2 host cell entry, that the peripheral sense organs are a likely site for viral host cell entry, and that TPC2 plays a key role in the translocation of the virus through the endolysosomal system. IMPORTANCE Despite the development of effective vaccines to combat the COVID-19 pandemic, which help prevent the most life-threatening symptoms, full protection cannot be guaranteed, especially with the emergence of new viral variants. Moreover, some resistance to vaccination remains in certain age groups and cultures. As such, there is an urgent need for the development of new strategies and therapies to help combat this deadly disease. Here, we provide compelling evidence that the peripheral sensory organs of zebrafish possess several key components required for SARS-CoV-2 host cell entry. The nearly transparent larvae provide a most amenable complementary platform to investigate the key steps of viral entry into host cells, as well as its spread through the tissues and organs. This will help in the identification of key viral entry steps for therapeutic intervention, provide an inexpensive model for screening novel antiviral compounds, and assist in the development of new and more effective vaccines.

ACE2, Circumventricular Organs and the Hypothalamus, and COVID-19

The SARS-CoV-2 virus gains entry to cells by binding to angiotensin-converting enzyme 2 (ACE2). Since circumventricular organs and parts of the hypothalamus lack a blood-brain barrier, and immunohistochemical studies demonstrate that ACE2 is highly expressed in circumventricular organs which are intimately connected to the hypothalamus, and the hypothalamus itself, these might be easy entry points for SARS-CoV-2 into the brain via the circulation. High ACE2 protein expression is found in the subfornical organ, area postrema, and the paraventricular nucleus of the hypothalamus (PVH). The subfornical organ and PVH are parts of a circuit to regulate osmolarity in the blood, through the secretion of anti-diuretic hormone into the posterior pituitary. The PVH is also the stress response centre in the brain. It controls not only pre-ganglionic sympathetic neurons, but is also a source of corticotropin-releasing hormone, that induces the secretion of adrenocorticotropic hormone from the anterior pituitary. It is proposed that the function of ACE2 in the circumventricular organs and the PVH could be diminished by binding with SARS-CoV-2, thus leading to a reduction in the ACE2/Ang (1-7)/Mas receptor (MasR) signalling axis, that modulates ACE/Ang II/AT1R signalling. This could result in increased presympathetic activity/neuroendocrine secretion from the PVH, and effects on the hypothalamic-pituitary-adrenal axis activity. Besides the bloodstream, the hypothalamus might also be affected by SARS-CoV-2 via transneuronal spread along the olfactory/limbic pathways. Exploring potential therapeutic pathways to prevent or attenuate neurological symptoms of COVID-19, including drugs which modulate ACE signalling, remains an important area of unmet medical need.

Neurological Manifestations of SARS-CoV2 Infection: A Narrative Review

The COVID-19 virus frequently causes neurological complications. These have been described in various forms in adults and children. Headache, seizures, coma, and encephalitis are some of the manifestations of SARS-CoV-2-induced neurological impairment. Recent publications have revealed important aspects of viral pathophysiology and its involvement in nervous-system impairment in humans. We evaluated the latest literature describing the relationship between COVID-19 infection and the central nervous system. We searched three databases for observational and interventional studies in adults published between December 2019 and September 2022. We discussed in narrative form the neurological impairment associated with COVID-19, including clinical signs and symptoms, imaging abnormalities, and the pathophysiology of SARS-CoV2-induced neurological damage.

SARS-CoV-2 mediated neurological disorders in COVID-19: Measuring the pathophysiology and immune response

The emergence of beta-coronavirus SARS-CoV-2 gets entry into its host cells by recognizing angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRESS2) receptors, which are responsible for coronavirus diseases-2019 (COVID-19). Global communities have been affected by COVID-19, especially caused the neurological complications and other critical medical issues. COVID-19 associated complications appear in aged people with underlying neurological states, especially in Parkinson's disease (PD) and Alzheimer's disease (AD). ACE2 receptors abundantly expressed in dopamine neurons may worsen the motor symptoms in PD and upregulates in SARS-CoV-2 infected aged patients' brain with AD. Immune-mediated cytokines released in SARS-CoV-2 infection lead to an indirect immune response that damages the central nervous system. Extreme cytokines release (cytokine storm) occurs due to aberrant immune pathways, and activation in microglial propagates CNS damage in COVID-19 patients. Here, we have explored the pathophysiology, immune responses, and long-term neurological impact on PD and AD patients with COVID-19. It is also a crucial step to understanding COVID-19 pathogenesis to reduce fatal outcomes of neurodegenerative diseases.

SARS-CoV-2-specific T cells in unexposed adults display broad trafficking potential and cross-react with commensal antigens

The baseline composition of T cells directly affects later response to pathogens, but the complexity of precursor states remains poorly defined. Here, we examined the baseline state of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T cells in unexposed individuals. SARS-CoV-2-specific CD4+ T cells were identified in prepandemic blood samples by major histocompatibility complex (MHC) class II tetramer staining and enrichment. Our data revealed a substantial number of SARS-CoV-2-specific T cells that expressed memory phenotype markers. Integrated phenotypic analyses demonstrated diverse preexisting memory states that included cells with distinct polarization features and trafficking potential to barrier tissues. T cell clones generated from tetramer-labeled cells cross-reacted with antigens from commensal bacteria in the skin and gastrointestinal tract. Direct ex vivo tetramer staining for one spike-specific population showed a similar level of cross-reactivity to sequences from endemic coronavirus and commensal bacteria. These data highlight the complexity of precursor T cell repertoire and implicate noninfectious exposures to common microbes as a key factor that shapes human preexisting immunity to SARS-CoV-2.

Brain cortical alterations in COVID-19 patients with neurological symptoms

Background

Growing evidence suggests that the central nervous system is affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), since infected patients suffer from acute and long-term neurological sequelae. Nevertheless, it is currently unknown whether the virus affects the brain cortex. The purpose of this study was to assess the cortical gray matter volume, the cortical thickness, and the cortical surface area in a group of SARS-CoV-2 infected patients with neurological symptoms compared to healthy control subjects. Additionally, we analyzed the cortical features and the association with inflammatory biomarkers in the cerebrospinal fluid (CSF) and plasma.

Materials and methods

Thirty-three patients were selected from a prospective cross-sectional study cohort during the ongoing pandemic (August 2020-April 2021) at the university hospitals of Basel and Zurich (Switzerland). The group included patients with different neurological symptom severity (Class I: nearly asymptomatic/mild symptoms, II: moderate symptoms, III: severe symptoms). Thirty-three healthy age and sex-matched subjects that underwent the same MRI protocol served as controls. For each anatomical T1w MPRAGE image, regional cortical gray matter volume, thickness, and surface area were computed with FreeSurfer. Using a linear regression model, cortical measures were compared between groups (patients vs. controls; Class I vs. II-III), with age, sex, MRI magnetic field strength, and total intracranial volume/mean thickness/total surface area as covariates. In a subgroup of patients, the association between cortical features and clinical parameters was assessed using partial correlation adjusting for the same covariates. P-values were corrected using a false discovery rate (FDR).

Results

Our findings revealed a lower cortical volume in COVID-19 patients' orbitofrontal, frontal, and cingulate regions than in controls (p < 0.05). Regional gray matter volume and thickness decreases were negatively associated with CSF total protein levels, the CSF/blood-albumin ratio, and CSF EN-RAGE levels.

Conclusion

Our data suggest that viral-triggered inflammation leads to neurotoxic damage in some cortical areas during the acute phase of a COVID-19 infection in patients with neurological symptoms.

Analysis of SARS-CoV-2 viral loads in stool samples and nasopharyngeal swabs from COVID-19 patients in the United Arab Emirates

Coronavirus disease 2019 (COVID-19) was first identified in respiratory samples and was found to commonly cause cough and pneumonia. However, non-respiratory symptoms including gastrointestinal disorders are also present and a big proportion of patients test positive for the virus in stools for a prolonged period. In this cross-sectional study, we investigated viral load trends in stools and nasopharyngeal swabs and their correlation with multiple demographic and clinical factors. The study included 211 laboratory-confirmed cases suffering from a mild form of the disease and completing their isolation period at a non-hospital center in the United Arab Emirates. Demographic and clinical information was collected by standardized questionnaire and from the medical records of the patient. Of the 211 participants, 25% tested negative in both sample types at the time of this study and 53% of the remaining patients had detectable viral RNA in their stools. A positive fecal viral test was associated with male gender, diarrhea as a symptom, and hospitalization during infection. A positive correlation was also observed between a delayed onset of symptoms and a positive stool test. Viral load in stools positively correlated with, being overweight, exercising, taking antibiotics in the last 3 months and blood type O. The viral load in nasopharyngeal swabs, on the other hand, was higher for blood type A, and rhesus positive (Rh factor). Regression analysis showed no correlation between the viral loads measured in stool and nasopharyngeal samples in any given patient. The results of this work highlight the factors associated with a higher viral count in each sample. It also shows the importance of stool sample analysis for the follow-up and diagnosis of recovering COVID-19 patients.

Probiotics in the Management of Mental and Gastrointestinal Post-COVID Symptomes

Patients with “post-COVID” syndrome manifest with a variety of signs and symptoms that continue/develop after acute COVID-19. Among the most common are gastrointestinal (GI) and mental symptoms. The reason for symptom occurrence lies in the SARS-CoV-2 capability of binding to exact receptors, among other angiotensin converting enzyme 2 (ACE2) receptors in gastrointestinal lining and neuropilin-1 (NRP-1) in the nervous system, which leads to loss of gastrointestinal and blood-brain barriers integrity and function. The data are mounting that SARS-CoV-2 can trigger systemic inflammation and lead to disruption of gut-brain axis (GBA) and the development of disorders of gut brain interaction (DGBIs). Functional dyspepsia (FD) and irritable bowel syndrome (IBS) are the most common DGBIs syndromes. On the other hand, emotional disorders have also been demonstrated as DGBIs. Currently, there are no official recommendations or recommended procedures for the use of probiotics in patients with COVID-19. However, it can be assumed that many doctors, pharmacists, and patients will want to use a probiotic in the treatment of this disease. In such cases, strains with documented activity should be used. There is a constant need to plan and conduct new trials on the role of probiotics and verify their clinical efficacy for counteracting the negative consequences of COVID-19 pandemic. Quality control is another important but often neglected aspect in trials utilizing probiotics in various clinical entities. It determines the safety and efficacy of probiotics, which is of utmost importance in patients with post-acute COVID-19 syndrome.

Clinical Phenotypes and Mortality Biomarkers: A Study Focused on COVID-19 Patients with Neurological Diseases in Intensive Care Units

Purpose: To identify clinical phenotypes and biomarkers for best mortality prediction considering age, symptoms and comorbidities in COVID-19 patients with chronic neurological diseases in intensive care units (ICUs). Subjects and Methods: Data included 1252 COVID-19 patients admitted to ICUs in Cuba between January and August 2021. A k-means algorithm based on unsupervised learning was used to identify clinical patterns related to symptoms, comorbidities and age. The Stable Sparse Classifiers procedure (SSC) was employed for predicting mortality. The classification performance was assessed using the area under the receiver operating curve (AUC). Results: Six phenotypes using a modified v-fold cross validation for the k-means algorithm were identified: phenotype class 1, mean age 72.3 years (ys)-hypertension and coronary artery disease, alongside typical COVID-19 symptoms; class 2, mean age 63 ys-asthma, cough and fever; class 3, mean age 74.5 ys-hypertension, diabetes and cough; class 4, mean age 67.8 ys-hypertension and no symptoms; class 5, mean age 53 ys-cough and no comorbidities; class 6, mean age 60 ys-without symptoms or comorbidities. The chronic neurological disease (CND) percentage was distributed in the six phenotypes, predominantly in phenotypes of classes 3 (24.72%) and 4 (35,39%); χ² (5) 11.0129 p = 0.051134. The cerebrovascular disease was concentrated in classes 3 and 4; χ² (5) = 36.63, p = 0.000001. The mortality rate totaled 325 (25.79%), of which 56 (17.23%) had chronic neurological diseases. The highest in-hospital mortality rates were found in phenotypes 1 (37.22%) and 3 (33.98%). The SSC revealed that a neurological symptom (ageusia), together with two neurological diseases (cerebrovascular disease and Parkinson's disease), and in addition to ICU days, age and specific symptoms (fever, cough, dyspnea and chilliness) as well as particular comorbidities (hypertension, diabetes and asthma) indicated the best prediction performance (AUC = 0.67). Conclusions: The identification of clinical phenotypes and mortality biomarkers using practical variables and robust statistical methodologies make several noteworthy contributions to basic and experimental investigations for distinguishing the COVID-19 clinical spectrum and predicting mortality.

Therapeutic potential of P2X7 purinergic receptor modulation in the main organs affected by the COVID-19 cytokine storm

Defined by the World Health Organization as a global public health pandemic, coronavirus 2019 (COVID-19) has a global impact and the death of thousands of people. The "severe acute respiratory syndrome coronavirus 2" virus (SARS-CoV-2) is the etiologic agent of this disease, which uses the angiotensin-converting enzyme receptor 2 (ACE2) to infect the body, so any organ that expresses the gene ACE2 is a possible target for the new coronavirus. In addition, in severe cases of COVID-19, a cytokine storm occurs, which triggers widespread systemic inflammation due to the uncontrolled release of proinflammatory cytokines. In this perspective, the modulation of purinergic receptors are highlighted in the literature as a possible therapy, considering its application in other viral infections and systemic inflammation. Therefore, the objective of this review is to gather information on the modulation of the P2X7 receptor in the main organs directly affected by the virus and by the cytokine storm: heart, brain, lung, liver and kidneys. Thus, demonstrating possible therapies for reducing inflammation, as well as reducing the level of morbidity and mortality of COVID-19.

Medicinal Herbs in the Relief of Neurological, Cardiovascular, and Respiratory Symptoms after COVID-19 Infection A Literature Review

COVID-19 infection causes complications, even in people who have had a mild course of the disease. The most dangerous seem to be neurological ailments: anxiety, depression, mixed anxiety-depressive (MAD) syndromes, and irreversible dementia. These conditions can negatively affect the respiratory system, circulatory system, and heart functioning. We believe that phytotherapy can be helpful in all of these conditions. Clinical trials confirm this possibility. The work presents plant materials (Valeriana officinalis, Melissa officinalis, Passiflora incarnata, Piper methysticum, Humulus lupulus, Ballota nigra, Hypericum perforatum, Rhodiola rosea, Lavandula officinalis, Paullinia cupana, Ginkgo biloba, Murraya koenigii, Crataegus monogyna and oxyacantha, Hedera helix, Polygala senega, Pelargonium sidoides, Lichen islandicus, Plantago lanceolata) and their dominant compounds (valeranon, valtrate, apigenin, citronellal, isovitexin, isoorientin, methysticin, humulone, farnesene, acteoside, hypericin, hyperforin, biapigenin, rosavidin, salidroside, linalool acetate, linalool, caffeine, ginkgolide, bilobalide, mihanimbine, epicatechin, hederacoside C,α-hederine, presegenin, umckalin, 6,7,8-trixydroxybenzopyranone disulfate, fumaroprotocetric acid, protolichesteric acid, aucubin, acteoside) responsible for their activity. It also shows the possibility of reducing post-COVID-19 neurological, respiratory, and cardiovascular complications, which can affect the functioning of the nervous system.

COVID-19 and Neurodegenerative Diseases: Prion-Like Spread and Long-Term Consequences

COVID-19 emerged as a global pandemic starting from Wuhan in China and spread at a lightning speed to the rest of the world. One of the potential long-term outcomes that we speculate is the development of neurodegenerative diseases as a long-term consequence of SARS-CoV-2 especially in people that have developed severe neurological symptoms. Severe inflammatory reactions and aging are two very strong common links between neurodegenerative diseases and COVID-19. Thus, patients that have very high viral load may be at high risk of developing long-term adverse neurological consequences such as dementia. We hypothesize that people with neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and aged people are at higher risk of getting the COVID-19 than normal adults. The basis of this hypothesis is the fact that SARS-CoV-2 uses as a receptor angiotensin-converting enzyme 2 to enter the host cell and that this interaction is calcium-dependent. This could then suggest a direct relationship between neurodegenerative diseases, ACE-2 expression, and the susceptibility to COVID-19. The analysis of the available literature showed that COVID-19 virus is neurotropic and was found in the brains of patients infected with this virus. Furthermore, that the risk of having the infection increases with dementia and that infected people with severe symptoms could develop dementia as a long-term consequence. Dementia could be developed following the acceleration of the spread of prion-like proteins. In the present review we discuss current reports concerning the prevalence of COVID-19 in dementia patients, the individuals that are at high risk of suffering from dementia and the potential acceleration of prion-like proteins spread following SARS-CoV-2 infection.

Longitudinally extensive transverse myelitis (LETM) secondary to SARS‐CoV‐2 infection: A recent reality in spinal cord injury rehabilitation

Transverse myelitis can be a complication of SARS‐CoV‐2 infection. We report the case of a transverse myelitis related to SARS‐CoV‐2 infection. Beyond the disease itself, neurological involvement affects functionality. In this situation, physical and rehabilitation medicine plays a crucial role in managing patient rehabilitation.

Neuropsychological Outcomes in Adult Patients and Survivors of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is believed to affect central nervous system functions through various indirect, and possibly direct, mechanisms. We are only now beginning to understand the possible effects of the virus on human cognition. This review summarizes extant yet limited literature on clinical neuropsychological findings in adult coronavirus disease 2019 (COVID-19) patients and survivors. Neuropsychological outcomes were often in the form of cognitive screen results, although various studies administered comprehensive batteries. With respect to screens, the Montreal Cognitive Assessment appeared relatively sensitive to cognitive dysfunction associated with COVID-19. Patients and survivors presented with weaknesses on screens and comprehensive batteries, although the pattern of these weaknesses was not specific to etiology. Broadly, weaknesses were suggestive of executive dysfunction, although more than one study did not detect significant impairment. Weaknesses should be interpreted cautiously due to potential confounds/contributing factors (weaknesses may partly reflect psychiatric sequelae; weaknesses may be over-interpreted due to inadequate assessment of premorbid functioning). Studies reported different approaches in defining impairment, likely contributing to variable findings. The current review discusses ongoing efforts to harmonize approaches to evaluating neuropsychological functioning globally, as well as emphasizes taking a comprehensive approach towards understanding how the disease affects cognition.

SARS-CoV-2 entry sites are present in all structural elements of the human glossopharyngeal and vagal nerves: Clinical implications

Background

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections result in the temporary loss of smell and taste in about one third of confirmed cases.

Methods

We used immunohistochemistry to confirm the presence of ACE2, NRP1 and TMPRSS2 in two cranial nerves (IX and X) that mediate taste where they leave/join the medulla. Samples from three (two paraffin embedded and one frozen) postmortem samples were studied (facial (VII) nerve was not available). We also performed immunohistochemistry using the same antibodies in two human cell lines (oligodendrocytes and fibroblasts), and we isolated RNA from one nerve and performed PCR to confirm the presence of the mRNAs that encode the proteins visualized.

Findings

All three of the proteins (ACE-2, NRP1 and TMPRSS2) required for SARS-CoV-2 infections appear to be present in all cellular components (Schwann cells, axons, vascular endothelium, and connective tissue) of the human IXth and Xth nerves near the medulla. We also found their mRNAs in the nerve and in human oligodendrocytes and fibroblasts which were stained by antibodies directed at the three proteins examined.

Interpretation

Infection of the IXth and Xth nerves by the SARS-CoV-2 virus is likely to cause the loss of taste experienced by many Covid patients. Migration of the virus from the oral cavity through these nerves to brainstem respiratory centers might contribute to the problems that patients experience.

Funding

This study was supported by the Intramural Research Program of the National Institute of Dental and Craniofacial Research (NIDCR), NIH (intramural project no. ZDE000755-01), and the Human Brain Tissue Bank, Semmelweis University, Budapest, Hungary from the Hungarian Brain Research Program (2017-1.2.1-NKP-2017-00002).

Does COVID-19 increase the long-term relapsing-remitting multiple sclerosis clinical activity? A cohort study

Background

Some current evidence is pointing towards an association between COVID-19 and worsening of multiple sclerosis (MS), stressing the importance of preventing COVID-19 among people with MS (pwMS). However, population-based evidence regarding the long-term post-COVID-19 course of relapsing-remitting multiple sclerosis (RRMS) was limited when this study was initiated.

Objective

To detect possible changes in MS clinical disease activity after COVID-19.

Methods

We conducted an observational study from July 2020 until July 2021 in the Isfahan MS clinic, comparing the trends of probable disability progression (PDP) – defined as a three-month sustained increase in expanded disability status scale (EDSS) score – and relapses before and after probable/definitive COVID-19 diagnosis in a cohort of people with RRMS (pwRRMS).

Results

Ninety pwRRMS were identified with definitive COVID-19, 53 of which were included in the final analysis. The PDP rate was significantly (0.06 vs 0.19, P = 0.04), and the relapse rate was insignificantly (0.21 vs 0.30, P = 0.30) lower post-COVID-19, compared to the pre-COVID-19 period. The results were maintained after offsetting by follow-up period in the matched binary logistic model. Survival analysis did not indicate significant difference in PDP-free (Hazard Ratio [HR] [95% CI]: 0.46 [0.12, 1.73], P = 0.25) and relapse-free (HR [95% CI]: 0.69 [0.31, 1.53], P = 0.36) survivals between the pre- and post-COVID-19 periods. Sensitivity analysis resulted similar measurements, although statistical significance was not achieved.

Conclusion

While subject to replication in future research settings, our results did not confirm any increase in the long-term clinical disease activity measures after COVID-19 contraction among pwRRMS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02590-9.

SARS-CoV-2 Infects Primary Neurons from Human ACE2 Expressing Mice and Upregulates Genes Involved in the Inflammatory and Necroptotic Pathways

Transgenic mice expressing human angiotensin-converting enzyme 2 under the cytokeratin 18 promoter (K18-hACE2) have been extensively used to investigate the pathogenesis and tissue tropism of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Neuroinvasion and the replication of SARS-CoV-2 within the central nervous system (CNS) of K18-hACE2 mice is associated with increased mortality; although, the mechanisms by which this occurs remain unclear. In this study, we generated primary neuronal cultures from K18-hACE2 mice to investigate the effects of a SARS-CoV-2 infection. We also evaluated the immunological response to SARS-CoV-2 infection in the CNS of K18-hACE2 mice and mouse neuronal cultures. Our data show that neuronal cultures obtained from K18-hACE2 mice are permissive to SARS-CoV-2 infection and support productive virus replication. Furthermore, SARS-CoV-2 infection upregulated the expression of genes involved in innate immunity and inflammation, including IFN-α, ISG-15, CXCL10, CCL2, IL-6 and TNF-α, in the neurons and mouse brains. In addition, we found that SARS-CoV-2 infection of neurons and mouse brains activates the ZBP1/pMLKL-regulated necroptosis pathway. Together, our data provide insights into the neuropathogenesis of SARS-CoV-2 infection in K18-hACE2 mice.

N, B. V, S. R, A. S. COVID-19: Invasion, pathogenesis and possible cure - A review

Today, Coronavirus disease (COVID-19) which is believed to be transmitted from bats to humans where the people of Wuhan city, China exposed to the wet animal market is an important international public health anxiety (Xiong et al., 2020). Although, several measures were undertaken to treat the diseases by various medical advancements and by a variety of treatment procedures, still the mortality is higher. Hence, social distancing has been implemented to control the current outburst of this pandemic which spreads through human to human transmission. As a consequence, there is a need to completely understand the route of invasions of the virus into the humans and the target receptors besides the other factors leading to the disease. Several vaccines and drugs have been developed with its own pros and cons. Many are still under the various phase of R&D and clinical trials. Here we highlight the possible entry molecules, pathogenesis, symptomatology, probable cure and the recently developed vaccines for the existing pandemic due to the COVID-19.

Distinct Symptoms and Underlying Comorbidities with Latitude and Longitude in COVID-19: A Systematic Review and Meta-Analysis

The coronavirus disease 2019 (COVID-19) pandemic is straining global health resources, and the prevalence of severe disease appears to vary across countries. In accordance with PRISMA guidelines, we performed a systematic review and meta-analysis of clinical features and underlying medical conditions of COVID-19. Eighty-seven studies, involving 1,434,931 COVID-19 patients from the Americas, Asia, Europe, and Oceania, were included. Geographically, the rate of severity was highest in Asia (95% confidence interval (CI) 0.23‒0.30). The rates of comorbidities of COVID-19 patients in the Americas were significantly higher than those in Asia. Most Asian patients had fever (95%CI 0.70‒0.81), and most Oceanian patients had cough (95%CI 0.68‒0.70) as their prevalent symptom. Dyspnea was common in the Americas (95%CI 0.33‒0.64), Europe (95%CI 0.29‒0.64), and high latitude regions (95%CI 0.53‒0.82). European patients exhibited significantly high rates of loss of smell and taste (95%CI 0.60-0.97). In low-latitude regions, cancer (95%CI 14.50‒4.89) had the strongest correlation with illness severity. Comorbid diseases and clinical manifestations of severe COVID-19 patients vary substantially between latitudes and longitudes. Region-specific care should be considered to treat and improve the prognosis of COVID-19 patients.

SARS-CoV-2 entry sites are present in all structural elements of the human glossopharyngeal and vagal nerves: clinical implications

Severe acute respiratory syndrome coronavirus (SARS-CoV-2) infections result in the temporary loss of smell and taste (anosmia and dysgeusia) in about one third of confirmed cases. Several investigators have reported that the viral spike protein receptor is present in olfactory neurons. However, no study has been published to date showing the presence of viral entry sites angiotensin-converting enzyme 2 (ACE2), neuropilin1 (NRP1), and TMPRSS2, the serine protease necessary for priming the viral proteins, in human nerves that are responsible for taste sensation (cranial nerves: VII, IX and X). We used immunocytochemistry to examine three postmortem donor samples of the IXth (glossopharyngeal) and Xth (vagal) cranial nerves where they leave/join the medulla from three donors to confirm the presence of ACE2, NRP1 and TMPRSS2. Two samples were paraffin embedded; one was a frozen sample. In addition to staining sections from the latter, we isolated RNA from it, made cDNA, and performed PCR to confirm the presence of the mRNAs that encode the proteins visualized. All three of the proteins required for SARS-CoV-2 infections appear to be present in the human IXth and Xth nerves near the medulla. Direct infection of these nerves by the COVID-19 virus is likely to cause the loss of taste experienced by many patients. In addition, potential viral spread through these nerves into the adjacent brainstem respiratory centers might also aggravate the respiratory problems patients are experiencing.

Optic neuropathies post-Covid 19 - review

The Corona virus infection started at the end of 2019 in Wuhan - China and spread rapidly throughout the world, generating the Covid 19 pandemic. The manifestations of the Covid disease were extremely varied, from a simple flu, with fever, cough, weakness, headache, joint pain, up to severe pneumonia, with severe acute respiratory syndrome (SARS-Cov2) and even death. The symptomatology of the disease, the evolution and the complications that appeared varied, depending on the associated pathology - diabetes mellitus (DM), hypertension (HT), the age and the immune status of the patient. Aim: The ocular manifestations related to Covid 19 were mostly represented by conjunctivitis, but the neurotropic character of Corona virus could justify the appearance of certain neuro-ophthalmological manifestations, such as: optic neuritis (ON), cranial nerve palsies, visual field (VF) anomalies. The aim of this paper was to research the cases of optic neuropathy post-Covid 19, published in the specialty literature between 2020 and 2022. The following were evaluated: risk factors, distribution by age group and gender, evolution and complications, as well as the clinical forms of optic neuropathies. Materials and methods: We used Google Scholar and PubMed databases to find articles on optic neuropathies related to the Covid-19 infection. We followed the articles published during the pandemic and selected 21 cases, belonging to 17 authors, irrespective of their origin and the language in which they were written. Results: 21 patients affected by ON in the Covid-19 disease, 11 women and 10 men, were mentioned. The optic neuropathies described by the authors were: retrobulbar optic neuropathy, only one associated with myelin oligodendrocyte glycoprotein (MOG), papillitis, neuroretinitis, anterior ischemic optic neuropathy (AION), out of which one arteritic anterior ischemic optic neuropathy (AAION) and the others non-arteritic anterior ischemic optic neuropathy (NAAION), one being related to pronation in an oro-tracheal intubated (OTI) patient with acute respiratory distress syndrome (ARDS). Discussions: The neuro-ophthalmological complications associated with Covid 19 disease can be severe, so the patients should be monitored continuously. Many investigations (serological, immunological and imaging exams) are necessary to exclude other etiologies of ON. Conclusions: A complete ophthalmological exam is mandatory for each patient diagnosed with Covid 19 disease, even if they have ocular manifestations or not. Abbreviations: SARS-Cov2 = severe acute respiratory syndrome; DM = Diabetes mellitus; HT = Hypertension; ON = Optic neuritis; VF = Visual field ; NS = Nervous system; CRP = C-reactive Protein; CL = cytokines; IL = interleukins; TNFɑ = tumor necrosis factor; CNS = central nervous system; ACE = angiotensin-converting enzyme; CRVO = central retinal vein occlusion; MOG = myelin oligodendrocyte glycoprotein; MOG-AD = myelin oligodendrocyte glycoprotein antibody disease; BBB = blood-brain barrier; ARDS = acute respiratory distress syndrome; IOP = intraocular pressure; CVP = central venous pressure; MSOF = multiple systems organ failure; AAION = arteritic anterior ischemic optic neuropathy; NAION = non-arteritic anterior ischemic optic neuropathy; AION = anterior ischemic optic neuropathy; OCT = optical coherence tomography; CT = computer tomography; AFG = angiofluorography; MRI = magnetic resonance imaging; ESR = erythrocyte sedimentation rate; RF = rheumatoid factor; ANA = antinuclear antibodies; ANCA = antineutrophil cytoplasmic antibodies; AQP4 = anti aquaporin 4; NMO = neuromyelitis optica; CSF = cerebrospinal fluid; OTI = oro-tracheal intubated; VA = visual acuity; ONTT = optic neuritis treatment trial; RNFL = retinal nerve fiber layer; ICU = intensive care unit; LE = left eye; RE = right eye; MS = multiple sclerosis; ICH = intracranial hypertension; BCVA = best correction visual acuity; LP = light perception; APD = afferent pupillary defect; BM = biomicroscopy; PDN = prednisone; MTX = methotrexate; MTPN = methylprednisolone; NSAID = non-steroidal anti-inflammatory drugs; CGL = cells ganglion layer; VEP = visual evoked potential; CF = counting fingers.

Sensitivity Enhancement of Dual Gate FET Based Biosensor Using Modulated Dielectric for Covid Detection

This paper presents a dual gate dielectric modulated FET (DGDMFET) biosensor with enhanced sensitivity for covid detection. In earlier literature, the biosensors are operated using the surface interaction with the virus biomolecules that are reflected through a channel or gate. The downside of these types of sensors has limited sensitivity. In this paper, we have considered that the change in the dielectric constant due to virus proteins results in a significant shift in the threshold voltage of FET. Enhancement of sensitivity is done by using the novel dual metal gate arrangement with different work functions (higher at the source end and lower at the drain end) and the chromic oxide (Cr₂O₃) layer, which is carved out vertically to form nanogap. At the same time, interface charge density is maintained nearly equal to 1.0 × 10¹¹ cm⁻² at the Si-SiO₂ layer. To demonstrate the proposed biosensor, electrical parameters (electron concentration, surface potential, energy band distribution, and electric field) and the absolute percentage sensitivity of threshold voltage, subthreshold slope, ON current, and transconductance are evaluated and compared with related literature. The ATLAS device simulator is used for the simulation of the proposed device.

COVID-19 outcomes among pregnant and nonpregnant women at reproductive age in Egypt

BACKGROUND

To describe demographic, clinical and epidemiological characteristics of pregnant and nonpregnant women with confirmed COVID-19 at reproductive age and determine risk factors of COVID-19 severe outcomes during pregnancy.

METHODS

A retrospective study for females aged 18-49 with confirmed COVID-19 by RT-PCR in Egypt, February-July 2020. Data were obtained from Egypt National Surveillance, bivariate and multivariate analysis for demographic and clinical characteristics and outcomes of COVID-19 between pregnant and nonpregnant women including ICU admission, need for ventilator and death was performed.

RESULTS

A total of 23 095 females were identified, with mean (SD) age of 35.1 (8.1) year. Of those, 408 (1.8%) were pregnant, with mean (SD) age of 29.3 (8.1) years. Compared to nonpregnant, pregnant patients were more likely to be admitted to hospital (OR = 1.7 CI = 1.4-2.1), ICU (OR = 2.4, CI = 1.3-4.3), need ventilator (OR = 3.9, CI = 2.1-7.4) and have severe outcome (OR = 3.0, CI = 1.9-4.7). Factors associated with severe outcome included: pregnancy, age > 30 years, underlying medical conditions, and living in rural areas.

CONCLUSION

Pregnant women with COVID-19 are at higher risk of severe symptoms and outcome including ICU admission, requiring ventilator and death. To reduce risk of severe outcome, counseling about for seeking medical care and health education about COVID-19 preventive measures should be performed.

SARS-CoV-2-specific T cells in unexposed adults display broad trafficking potential and cross-react with commensal antigens

The baseline composition of T cells directly impacts later response to a pathogen, but the complexity of precursor states remains poorly defined. Here we examined the baseline state of SARS-CoV-2 specific T cells in unexposed individuals. SARS-CoV-2 specific CD4 + T cells were identified in pre-pandemic blood samples by class II peptide-MHC tetramer staining and enrichment. Our data revealed a substantial number of SARS-CoV-2 specific T cells that expressed memory phenotype markers, including memory cells with gut homing receptors. T cell clones generated from tetramer-labeled cells cross-reacted with bacterial peptides and responded to stool lysates in a MHC-dependent manner. Integrated phenotypic analyses revealed additional precursor diversity that included T cells with distinct polarized states and trafficking potential to other barrier tissues. Our findings illustrate a complex pre-existing memory pool poised for immunologic challenges and implicate non-infectious stimuli from commensal colonization as a factor that shapes pre-existing immunity.

ONE SENTENCE SUMMARY

Pre-existing immunity to SARS-CoV-2 contains a complex pool of precursor lymphocytes that include differentiated cells with broad tissue tropism and the potential to cross-react with commensal antigens.

Neurological complications and infection mechanism of SARS-COV-2

Currently, SARS-CoV-2 has caused a global pandemic and threatened many lives. Although SARS-CoV-2 mainly causes respiratory diseases, growing data indicate that SARS-CoV-2 can also invade the central nervous system (CNS) and peripheral nervous system (PNS) causing multiple neurological diseases, such as encephalitis, encephalopathy, Guillain-Barré syndrome, meningitis, and skeletal muscular symptoms. Despite the increasing incidences of clinical neurological complications of SARS-CoV-2, the precise neuroinvasion mechanisms of SARS-CoV-2 have not been fully established. In this review, we primarily describe the clinical neurological complications associated with SARS-CoV-2 and discuss the potential mechanisms through which SARS-CoV-2 invades the brain based on the current evidence. Finally, we summarize the experimental models were used to study SARS-CoV-2 neuroinvasion. These data form the basis for studies on the significance of SARS-CoV-2 infection in the brain.

Post-acute sequelae of COVID-19: Evidence of mood & cognitive impairment

Acute health consequences associated with coronavirus disease 2019 (COVID-19) infection have been thoroughly characterized; however, long-term impacts are not yet understood. Post-acute sequelae of COVID-19 (PASC), also known as Long COVID syndrome, is the persistence of COVID-19 symptoms long after viral infection. In addition to physical symptoms, those with PASC experience changes in mental health, but few studies have empirically examined these effects. The current study investigated mood and cognitive functioning in individuals who have recovered from COVID-19 infection. We recruited 100 male and female adults (M ​= ​30 years old) with no history of mood or cognitive impairment prior to the COVID-19 pandemic (Jan. 2020). Half of the subjects were healthy controls (i.e., no prior COVID-19 infection) and half had received a past COVID-19 diagnosis (ascertained by PCR or antibody test) but were no longer infectious. Participants completed self-reported measures of stress, depression, and anhedonia, as well as the Attention Network Test (ANT), a behavioural measure of attentional alerting, orienting and executive functioning. Relative to controls, depression and anhedonia were significantly higher in the past-COVID group. Selective impairment in attention was observed in the past-COVID group, marked by deficits in executive functioning while alerting and orienting abilities remained intact. Effects were most pronounced among individuals diagnosed 1-4 months prior to assessment. There were no group differences in pandemic-related experiences with respect to social interaction, social distancing, or isolation. The past-COVID group scored significantly higher on perceived stress; however, this did not moderate any effects observed on mood or cognition. These findings implicate a protracted reaction to the virus, possibly via prolonged inflammation, contributing to sustained mood dysregulation and cognitive impairment. Future research should examine the neural and physiological underpinnings of PASC, particularly mechanisms that promote psychiatric sequelae 1-4 months following diagnosis.

Assessment of olfactory and gustatory functions in COVID-19 patients

Background/aim

This study aims to evaluate of olfactory and gustatory functions of COVID-19 patients and possible risk factors for olfactory and gustatory dysfunctions.

Materials and methods

The cross-sectional study included adult patients who were diagnosed with COVID-19 in Gazi University Hospital between April 2020 and June 2020. Volunteered patients participated in a survey in which olfactory and gustatory functions and various clinical information were questioned. Sinonasal Outcome Test-22 was also administrated to all patients.

Results

A hundred and seventy-one patients participated in this study. Olfactory and gustatory dysfunctions rates were 10.5% (n: 18) and 10.5% (n: 18), respectively. Patients without any symptom other than smell and taste dysfunctions were clustered as group 1 and patients who are clinically symptomatic were clustered as group 2. Olfactory dysfunction occurred in 8% of group 1 and 17.4% of group 2 (p = 0.072). Gustatory dysfunction rate of smokers was 19.7% and significantly higher than gustatory dysfunction rate of nonsmokers (5.5%) (p = 0.007). Twenty-seven-point-eight percent of the patients with olfactory dysfunction (n = 5) were male and 72.2% (n: 13) were female. Sex did not show significant effect on rate of olfactory dysfunction. Twenty-five patients participated in psychophysical olfactory function test. No participant reported olfactory dysfunction at the time of test. Of the participants, 64% (n: 16) were normosmic and 36% (n: 9) were hyposmic according to Sniffin’ Stick test.

Conclusion

Olfactory and gustatory dysfunctions are more common in patients who are clinically symptomatic than those diagnosed during contact tracing. Objective tests may show that frequency of olfactory dysfunction is greater than frequency of self-reported olfactory dysfunction.

Intermittent Frontal Rhythmic Discharges as an Electroencephalogram Biomarker of Acute SARS-CoV-2 Infection-Associated Encephalopathy in Children

Data on neurological sequelae of COVID-19 infection in children are sparse. Neurotropic and neuroinvasive potentials of the SARS-CoV-2 virus are a matter of ongoing scientific debate and not yet well understood. Most of the reported symptoms are nonspecific including headache, encephalopathy, weakness, and as a part of multisystem inflammatory response syndrome. Few observational studies have reported acute encephalopathy to be one of the neurological manifestations of COVID-19 infection, mostly in adults. A little is known about epileptogenesis or electroencephalogram (EEG) findings in this limited cohort of pediatric patients. We report a 17-year-old female with type 1 diabetes mellitus (DM), who presented with two weeks history of intermittent headaches, followed by a one-day history of acute change in behavior in the form of prolonged staring, decreased speech, confusion, and alternating periods of agitation and sleepiness. No fever or respiratory symptoms. Her blood glucose was normal. Brain MRI was unremarkable. Cerebrospinal fluid (CSF) studies showed 1000 RBCs, no WBCs, normal glucose/protein, negative culture, and negative infectious PCR, and autoimmune panels. She was found to be positive for SARS-CoV-2 PCR with negative IgG. Her EEG showed remarkable background slowing and frequent frontal intermittent rhythmic discharges. She was managed with high-dose steroids with the full clinical recovery of all symptoms at discharge, as well as normalization of subsequent EEG studies. We hypothesize there may be some specific seizure characteristics or EEG patterns in patients with pediatric COVID-19 infection and concomitant acute encephalopathy. It is perhaps reasonable to obtain EEG studies in children who test positive for SARS-CoV-2 and report central neurological symptoms. Long-term follow-up of this cohort of patients will be helpful to understand the clinical significance and implications of such neurophysiological studies.