COVID-19 neurotropism and implications for therapy

The mechanism underlying the pathogenesis of severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)infection in humans is poorly understood,although the cellular receptors which facilitate the virus fusion have been identified.Although the major symptoms of the infection have been identified as acute respiratory distress,pneumonia,and fever,recently,symptoms involving nervous system dysfunctions,including encephalopathy and stroke,have been detected.Herein,we comprehensively review the evidence that SARS-CoV-2 infection involves a neurotropic mechanism including a nose-brain-lung axis suggesting implications in therapy development.

Alzheimer’s disease risk after COVID-19:a view from the perspective of the infectious hypothesis of neurodegeneration

In light of the rising evidence of the association between viral and bacterial infections and neurodegeneration,we aimed at revisiting the infectious hypothesis of Alzheimer’s disease and analyzing the possible implications of COVID-19 neurological sequelae in long-term neurodegeneration.We wondered how SARS-CoV-2 could be related to the amyloid-βcascade and how it could lead to the pathological hallmarks of the disease.We also predict a paradigm change in clinical medicine,which now has a great opportunity to conduct prospective surveillance of cognitive sequelae and progression to dementia in people who suffered severe infections together with other risk factors for Alzheimer’s disease.

Advances in viral encephalitis:Viral transmission,host immunity,and experimental animal models

Viral infections have led to many public health crises and pandemics in the last few centuries.Neurotropic virus infection-induced viral encephalitis(VE),especially the symptomatic inflammation of the meninges and brain parenchyma,has attracted growing attention due to its high mortality and disability rates.Understanding the infectious routes of neurotropic viruses and the mechanism underlying the host immune response is critical to reduce viral spread and improve antiviral therapy outcomes.In this review,we summarize the common categories of neurotropic viruses,viral transmission routes in the body,host immune responses,and experimental animal models used for VE study to gain a deeper understanding of recent progress in the pathogenic and immunological mechanisms under neurotropic viral infection.This review should provide valuable resources and perspectives on how to cope with pandemic infections.

NEUROBIOLOGICAL EFFECTS OF NRCF DERIVED FROM DISTAL STUMPS OF MOTOR NERVE AND SENSORY NERVE AND b-FGF ON CULTURED MOTONEURON IN VITRO

Objective: To explore the mechanism of neurotropism in peripheral nerve regeneration by assessing the bioactivity of regeneration microcircumstance on motoneurons. Methods The motor branch Of femoral nerve to quadriceps was incised and the distal stump was sutured with one-end silicone chamber. The nerve regeneration chamber fluids from distal motor nerve stumps (motor branch of femoral nerve ) (MD-NRCF) was collected 7d post-operatively, and with the same method, nerve regeneration conditioned fluids from distal stumps nerve stumps (saphenous nerve ) (SD-NRCF) was collected. The dissociated rat’s motoneurons were co-cultured with MD-NRCF, SD-NRCF, basic fibroblast growth factor (b-FGF) and serum-free medium for 72h respectively and then were photographed under phase-contrast microscope. The longest neurites and cellbody areas of motoneurons from each group were measured by cell image processing computer system. MTT colorimetric assay was also used to measure cell activation. Results The cells of MD-NRCF group had significantly longer neurites than the other 3 groups, and their activation was also superior to those of the other groups. Conclusion These results indicate that MD-NRCF has more significant neurite-promoting and neurobiological effects on motoneuron than SD-NRCF and b-FGF.

Alternate paradigms on Zika virus-related complications:An analytical review

The proportion of the reported cases of Zika virus(ZIKV) infection reached the status of a pandemic. Numerous studies are being conducted on the isolation of ZIKV strains from various epidemics, diagnosis of the infections, various animal models and cell culture designs to study the pathogenesis of ZIKV in the attempts to find an effective ZIKV vaccine. This review focuses upon the 'Off-Spectrum' body of studies which analyses the epidemiology, pathogenesis and other attributes of ZIKV in the light of various dissident hypotheses.

Effects of COVID-19 on children with autism

The coronavirus disease 2019(COVID-19)pandemic affects all countries and populations worldwide,significantly impacting people with autism with a high risk of morbidity and mortality due to COVID-19.Approximately 25%of children with autism have an asymptomatic or symptomatic immune deficiency or dysfunction.In addition,they frequently have various comorbid conditions that increase the severity of COVID-19.In addition,severe COVID-19 during pregnancy may increase the risk of autism in the offspring.Furthermore,severe acute respiratory syndrome coronavirus 2 could target human nervous system tissues due to its neurotrophic effects.The COVID-19 pandemic intensely impacts many patients and families in the autism community,especially the complex management of autism-associated disorders during the complete lockdown.During the complete lockdown,children with autism had difficulties coping with the change in their routine,lack of access to special education services,limited physical space available,and problems related to food and sleep.Additionally,children with autism or intellectual disabilities are more liable to be abused by others during the pandemic when the standard community supports are no longer functioning to protect them.Early detection and vaccination of children with autism against COVID-19 are highly indicated.They should be prioritized for testing,vaccination,and proper management of COVID-19 and other infectious diseases.In this review,we discuss the various effects of COVID-19 on children with autism,the difficulties they face,the increased risk of infection during pregnancy,how to alleviate the impact of COVID-19,and how to correct the inequalities in children with autism.

Could autophagy dysregulation link neurotropic viruses to Alzheimer’s disease?

Neurotropic herpesviruses have been associated with the onset and progression of Alzheimer’s disease,a common form of dementia that afflicts a large percentage of elderly individuals.Interestingly,among the neurotropic herpesviruses,herpes simplex virus-1,human herpesvirus-6A,and human herpesvirus-6B have been reported to infect several cell types present in the central nervous system and to dysregulate autophagy,a process required for homeostasis of cells,especially neurons.Indeed autophagosome accumulation,indicating an unbalance between autophagosome formation and autophagosome degradation,has been observed in neurons of Alzheimer’s disease patients and may play a role in the intracellular and extracellular accumulation of amyloidβand in the altered protein tau metabolism.Moreover,herpesvirus infection of central nervous system cells such as glia and microglia can increase the production of oxidant species through the alteration of mitochondrial dynamics and promote inflammation,another hallmark of Alzheimer’s disease.This evidence suggests that it is worth further investigating the role of neurotropic herpesviruses,particularly human herpesvirus-6A/B,in the etiopathogenesis of Alzheimer’s disease.

Cortical spreading depression-induced preconditioning in the brain

Cortical spreading depression is a technique used to depolarize neurons. During focal or global ischemia, cortical spreading depression-induced preconditioning can enhance tolerance of further injury. However, the underlying mechanism for this phenomenon remains relatively unclear. To date, numerous issues exist regarding the experimental model used to precondition the brain with cortical spreading depression, such as the administration route, concentration of potassium chloride, induction time, duration of the protection provided by the treatment, the regional distribution of the protective effect, and the types of neurons responsible for the greater tolerance. In this review, we focus on the mechanisms underlying cor- tical spreading depression-induced tolerance in the brain, considering excitatory neurotransmission and metabolism, nitric oxide, genomic reprogramming, inflammation, neurotropic factors, and cellular stress response. Specifically, we clarify the procedures and detailed information regarding cortical spreading depression-induced preconditioning and build a foundation for more comprehensive investigations in the field of neural regeneration and clinical application in the future.

Brain-derived neurotropic factor and GABAergic transmission in neurodegeneration and neuroregeneration

Neurotoxicity induced by stress,radiation,chemicals,or metabolic diseases,is commonly associated with excitotoxicity,oxidative stress,and neuroinflammation.The pathological process of neurotoxicity induces neuronal death,interrupts synaptic plasticity in the brain,and is similar to that of diverse neurodegenerative diseases.Animal models of neurotoxicity have revealed that clinical symptoms and brain lesions can recover over time via neuroregenerative processes.Specifically,brain-derived neurotropic factor（BDNF） and gamma-aminobutyric acid（GABA）-ergic transmission are related to both neurodegeneration and neuroregeneration.This review summarizes the accumulating evidences that suggest a pathogenic role of BDNF and GABAergic transmission,their underlying mechanisms,and the relationship between BDNF and GABA in neurodegeneration and neuroregeneration.This review will provide a comprehensive overview of the underlying mechanisms of neuroregeneration that may help in developing potential strategies for pharmacotherapeutic approaches to treat neurotoxicity and neurodegenerative disease.

Phenylpropanoids as the biologically active compounds of the medicinal plants and phytopharmaceuticals

In the present paper are discussed the results of the investigations of the phenylpropanoids of the medicinal plants which are of the great interest as the sources of the neurotropic, adaptogenic, immunostimulating, antioxidative, and hepatoprotective preparations. There were shown the necessity of using of the standard samples of triandrin (Rhodiola rosea L. tissue cultures, Salix viminalis L. barks), rosavin (Rhodiola rosea L. rhizomes), syringin, or eleutheroside B [Eleutherococcus senticosus (Rupr. et Maxim.) Maxim. rhizomes, Syringa vulgaris L. barks], and silybin [Silybum marianum (L.) Gaertn. fruits] for purpose of the standardization of the corresponding drugs and pharmaceuticals. It was shown also the significance of γ-schizandrin, chicoric acid, rosmarinic acid and lavandoside for purposes of the standardization of raw material and preparations of Schizandra chinensis Baill. fruits and seeds, Echinacea purpurea (L.) Moench. herbs, Melissa officinalis L. herbs and Lavandula spica L. flowers respectively.

Correlation of prefrontal activity measured by near-infrared spectroscopy (NIRS) with mood, BDNF genotype and serum BDNF level in healthy individuals

Depression has been known to reduce the prefrontal activity associated with the execution of certain cognitive tasks, although whether a temporarily depressed or anxious mood in healthy individuals affects the prefrontal blood oxygen level during cognitive tasks is unknown. Combining the measurement of prefrontal activity with near-infrared spectroscopy (NIRS) and the two cognitive tasks, namely the letter version of the verbal fluency test (VFT-l) and the Stroop test, we measured the effect of a depressed or anxious mood and gender on the changes in the prefrontal oxygenated hemoglobin (Oxy-Hb) levels during those cognitive tests in healthy individuals. Depressed mood or anxious mood was assessed by the Hospital Anxiety and Depression Scale (HADS). Thereby we aimed to explore the possibility of NIRS measurement for detecting the early subclinical manifestation of major depression. Moreover, we examined the possible relationships between prefrontal activation and the functional Val66Met polymorphisms of the brain derived neurotropic factor (BDNF) gene and serum BDNF level. As a result, the increased prefrontal Oxy-Hb levels during cognitive tasks were significantly correlated with the severity of depressed mood in males. The course of the prefrontal Oxy-Hb increase was different depending on the cognitive tasks, i.e., the VFT-l or the Stroop test, in both genders. Correlations of BDNF genotype and serum BDNF level with the prefrontal Oxy-Hb levels during those cognitive tasks were negative. Our results suggest that the early subclinical manifestation of depressed mood in males might be detected by the NIRS measurement, which is not correlated with the individual properties of BDNF.

Serum Levels of Brain-Derived Neurotrophic Factor in Patients with Obsessive-Compulsive Disorder in a Japanese Population

A role of lower brain-derived neurotrophic factor (BDNF) content in the pathogenesis of several mental illnesses has been suggested, especially in major depression. It is not known whether BDNF is involved in the pathogenesis of obsessive-compulsive disorder (OCD). Herein, we assessed the serum BDNF content and its correlation with symptom severity in a Japanese population with OCD. The serum BDNF levels of OCD patients (n = 39) and healthy controls (n = 37) were measured by ELISA. The severity of OCD symptoms was assessed by the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) and the Beck Depression Inventory (BDI). The OCD patients’ BDNF levels were significantly higher than those of the controls (17.5 ± 7.3 vs. 12.7 ± 4.7) (p < 0.01). No correlation was observed between the OCD patients’ BDNF levels and their OCD symptoms as scored by the Y-BOCS. For all 76 subjects, the BDI scores were significantly negatively correlated with the serum BDNF levels. Our findings revealed that contrary to previous reports, the serum BDNF content in OCD patients could be higher than that of healthy subjects.

Long COVID:From olfactory dysfunctions to viral Parkinsonism

Neurological and psychiatric complications continue to be a public health concern in long coronavirus disease 2019(COVID-19).This varies from olfactory dysfunctions such as parosmia to cognitive and emotional challenges.Historically,the surge of neurological disorders followed the viral pandemics,for example,the emergence of Encephalitis Lethargica after the outbreak of Spanish Influenza.During and after COVID-19 infection,the problems associated with the sense of smell and the reports of affected olfactory and limbic brain areas are leading to a growing concern about the similarity with the symptoms and the pattern of degeneration observed at the onset of Parkinson's disease and Alzheimer's disease.These reports reveal the essentiality of long-term studies of olfactory and cognitive functions in the post-COVID era and the experiments using animal models to dissect the neural basis of these complications.In this manuscript,we summarize the research reporting the potential correlation between neurological disorders and viral pandemic outbreaks with a historical perspective.Further,we discuss the studies providing evidence of neurodegeneration due to severe acute respiratory syndrome coronavirus 2 infection by focusing on viral Parkinsonism.

Pathogenesis of enterovirus infection in central nervous system

Enteroviruses (EVs) are classified into 15 species according to their sequence diversity. They include four human EV (A, B, C, and D) and three rhinoviruses (A, B, and C), and cause diseases in millions of people worldwide. Generally, individuals with enteroviral infections have mild clinical symptoms, including respiratory illness, vomiting, diarrhea, dizziness, and fever. More importantly, some members of the human EV family are neurotropic pathogens that may cause a wide range of clinical diseases, such as aseptic meningitis and encephalitis. Previously, the EV that caused the most severe neurotropic symptoms was poliovirus (PV), a member of the EV C group. Poliovirus has been eliminated in most countries through a global vaccination campaign. Non-PV EVs infect the central nervous system (CNS) and are the major EVs causing neurological diseases. These human non-PV EVs include EV A (e.g., EV-A71, CVA6, and CVA16), B (e.g., CVA9 and CVB3, CVB5, echovirus 11 [E11], E30, and E7), C (e.g., CVA24), and D (e.g., EV-D68). Here, we review the relationship between EV infection and CNS diseases and advance in the use of cellular receptors and host immune responses during viral infection.

Taxonomy of Ochroconis, genus including opportunistic pathogens on humans and animals

The genus Ochroconis(Sympoventuriaceae,Venturiales)is revised and currently contains 13 species for which the phylogenetic position has been determined using multilocus sequencing.The older generic name Scolecobasidium is considered to be of doubtful identity because the type specimen is ambiguous.Within the Ochroconis lineage,phylogenetic distances of all markers analyzed are exceptionally large,both between and within species.A new genus Verruconis is proposed for the neurotropic opportunist Ochroconis gallopava.Species accepted within the lineages are keyed out on the basis of phenotypic characters.Main ecological traits within each species are discussed.Verruconis species are thermophilic and one of them is an important agent of infection in the brain,while Ochroconis is mesophilic,several species causing infections in cold-blooded animals.

长链多不饱和脂肪酸与学习记忆的关系及其分子机制

1 前言学习记忆是一个复杂的过程。它不仅包括突触传递及相关的信号事件,而且涉及突触的可塑性和基因转录后新蛋白质的合成。有关脑源神经营养因子(brain-derived neurotrophic factor, BDNF)、神经生长因子、神经营养因子-4/5(neurotrophin-4/5)的研究表明。

Trans-synaptic Neural Circuit-Tracing with Neurotropic Viruses

A central objective in deciphering the nervous system in health and disease is to define the connections of neurons. The propensity of neurotropic viruses to spread among synaptically-linked neurons makes them ideal for mapping neural circuits. So far, several classes of viral neuronal tracers have become available and provide a powerful toolbox for delineating neural networks. In this paper, we review the recent developments of neurotropic viral tracers and highlight their unique properties in revealing patterns of neuronal connections.

Cortical Organization of Centrifugal Afferents to the Olfactory Bulb: Mono-and Trans-synaptic Tracing with Recombinant Neurotropic Viral Tracers

Sensory processing is strongly modulated by different brain and behavioral states,and this is based on the top-down modulation.In the olfactory system,local neural circuits in the olfactory bulb(OB)are innervated by centrifugal afferents in order to regulate the processing of olfactory information in the OB under different behavioral states.The purpose of the present study was to explore the organization of neural networks in olfactory-related cortices and modulatory nuclei that give rise to direct and indirect innervations to the glomerular layer(GL)of the OB at the whole-brain scale.Injection of different recombinant attenuated neurotropic viruses into the GL showed that it received direct inputs from each layer in the OB,centrifugal inputs from the ipsilateralanterior olfactory nucleus(AON),anterior piriform cortex(Pir),and horizontal limb of diagonal band of Broca(HDB),and various indirect inputs from bilateral cortical neurons in the AON,Pir,amygdala,entorhinal cortex,hippocampus,HDB,dorsal raphe,median raphe and locus coeruleus.These results provide a circuitry basis that will help further understand the mechanism by which olfactory informationprocessing in the OB is regulated.

Interactions between neurotropic pathogens, neuroinflammatory pathways, and autophagic neural cell death

In recent times, there has been a significant increase in studies focusing on immunological functions of autophagy, however, knowledge of its roles and regulations in the central nervous system remains unclear. Present reviews highlight the molecular cross talk between host cell autophagy with inflammatory pathways in the context of neuro-infections. Intracellular pathogens might have an ability to manipulate the autophagy regulation process. An augmented autophagy and inflammation at the site of infection is traditionally considered host protective. Moreover, host cell autophagy might also facilitate pathogen survivability and multiplication in the brain environment. Consequently, an excessive autophagy and neuroinflammatory process do put surrounding healthy brain tissue at risk of pathogen invasion. The question arises, whether there are any known direct interactions of intracellular neurotropic pathogens with this degradative pathway that favour intracerebral pathogen survival and growth? It is worth exploring any such cooperation between pathogen factors and altered immune pathways that modulate autophagy regulatory genes causing massive neuronal damage. A detailed understanding of molecular mechanisms in microbial pathogenesis, neuroinflammatory and neuronal autophagy pathways might identify novel therapeutic targets and diagnostic biomarkers.