A chaotic neural network mimicking an olfactory system and its application on image recognition

Based on the research of a biological olfactory system, a novel chaotic neural network model - K set model has been es- tablished. This chaotic neural network not only simulates the real brain activity of an olfactory system, but also presents a novel chaotic concept for signal processing and pattern recognition. The characteristics of the K set models are investigated and show that a KIII model can be used for image pattern classification.

From neurogenesis to neuronal regeneration: the amphibian olfactory system as a model to visualize neuronal development in vivo

How do individual neurons develop and how are they in- tegrated into neuronal circuitry？ To answer this question is essential to understand how the nervous system develops and how it is maintained during the adult life. A neural stem cell must go through several stages of maturation, including proliferation, migration, differentiation, and integration, to become fully embedded to an existing neuronal circuit. The knowledge on this topic so far has come mainly from cell culture studies. Studying the development of individual neurons within intact neuronal networks in vivo is inherently difficult. Most neurons are generated form neural stem cells during embryonic and early postnatal development.

Loss of CO_2 sensing by the olfactory system of CNGA3 knockout mice

Atmospheric CO2 can signal the presence of food, predators or environmental stress and trigger stereotypical behaviors in both vertebrates and invertebrates. Recent studies have shown that the necklace olfactory system in mice sensitively detects CO2 in the air. Olfactory CO2 neurons are believed to rely on cyclic gnanosine monophosphate （cGMP） as the key second messenger; however, the specific ion channel underlying CO2 responses remains unclear. Here we show that CO2-evoked neuronal and behavioral responses require cyclic nucleotide-gated （CNG） channels consisting of the CNGA3 subunit. Through Ca2＋-imaging, we found that CO2-triggered Ca2＋ influx was abolished in necklace olfactory sensory neurons （OSNs） of CNGA3-knockout mice. Olfactory detection tests using a Go/No-go paradigm showed that these knockout mice failed to detect 0.5% CO2. Thus, sensitive detection of atmospheric CO2 depends on the function of CNG channels consisting of the CNGA3 subunit in necklace OSNs. These data support the important role of the necklace olfactory system in CO2 sensing and extend our understanding of the signal transduction pathway mediating CO2 detection in mammals [Current Zoology 56 （6）： 793-799, 2010].

The olfactory system of Pieris brassicae caterpllars:from receptors to glomeruli

Tolfactory system of adult lepidopterans is among the best described neuronal circuits.However,comparatively little is known about the organization of the olfactory system in the larval stage of these insects.Here,we explore the expression of olfactory receptors and the organization of olfactory sensory neurons in caterpillars of Pieris brassicae,a significant pest species in Europe and a well-studied species for its chemical ecology.To describe the larval olfactory system in this species,we first analyzed the head transcriptome of third-instar larvae(L3)and identified 16 odorant receptors(ORs)including the OR coreceptor(Orco),13 ionotropic receptors(IRs),and 8 gustatory receptors(GRs).We then quantified the expression of these 16 ORs in different life stages,using qPCR,and found that the majority of ORs had significantly higher expression in the L4 stage than in the L3 and L5 stages,indicating that the larval olfactory system is not static throughout caterpillar development.Using an Orco-specific antibody,we identified all olfactory receptor neurons(ORNs)expressing the Orco protein in L3,L4,and L5 caterpillars and found a total of 34 Orco-positive ORNs,distributed among three sensilla on the antenna.The number of Orco-positive ORNs did not differ among the three larval instars.Finally,we used retrograde axon tracing of the antennal nerve and identified a mean of 15 glomeruli in the larval antennal center(LAC),suggesting that the caterpillar olfactory system follows a similar design as the adult olfactory system,although with a lower numerical redundancy.Taken together,our results provide a detailed analysis of the larval olfactory neurons in P brassicae,highlighting both the differences as well as the commonalities with the adult olfactory system.These findings contribute to a better understanding of the development of the olfactory system in insects and its life-stage-specific adaptations.

Olfactory dysfunction and its related molecular mechanisms in Parkinson’s disease

Changes in olfactory function are considered to be early biomarkers of Parkinson’s disease.Olfactory dysfunction is one of the earliest non-motor features of Parkinson’s disease,appearing in about 90%of patients with early-stage Parkinson’s disease,and can often predate the diagnosis by years.Therefore,olfactory dysfunction should be considered a reliable marker of the disease.However,the mechanisms responsible for olfactory dysfunction are currently unknown.In this article,we clearly explain the pathology and medical definition of olfactory function as a biomarker for early-stage Parkinson’s disease.On the basis of the findings of clinical olfactory function tests and animal model experiments as well as neurotransmitter expression levels,we further characterize the relationship between olfactory dysfunction and neurodegenerative diseases as well as the molecular mechanisms underlying olfactory dysfunction in the pathology of early-stage Parkinson’s disease.The findings highlighted in this review suggest that olfactory dysfunction is an important biomarker for preclinical-stage Parkinson’s disease.Therefore,therapeutic drugs targeting non-motor symptoms such as olfactory dysfunction in the early stage of Parkinson’s disease may prevent or delay dopaminergic neurodegeneration and reduce motor symptoms,highlighting the potential of identifying effective targets for treating Parkinson’s disease by inhibiting the deterioration of olfactory dysfunction.

Assessing the Adverse Impacts of PM_(2.5)on Olfactory System Using an Air-liquid Interface Culture Model of Primary Olfactory Epithelial Cells

The air-liquid interface(ALI)culture is a kind of recently developed system,which has proved its availability in simulating the biology of respiratory tract epithelial tissues.In this study,an ALI-based mouse primary olfactory epithelial cell(OEC)model was established to perform the exposure of PM_(2.5)(PM=particulate matter)collected from Dianshan Lake(Shanghai)and Wangdu(Hebei).The results showed that PM_(2.5)in both regions caused a decrease in cell viability in a dose-dependent manner.The 0.5 and 5µg/cm^(2)(around ambient concentrations)of PM_(2.5)disrupted OEC membrane integrity and produced oxidative stress with elevated indicators of malondialdehyde(MDA)and reactive oxygen species(ROS).In transcriptomic sequencing,the terms concerning inflammatory cytokines and second messenger cyclic adenosine-3′,5′-monophoshate(cAMP)were enriched in two treatments.The cytokine array showed the levels of some cytokines were altered,although inflammatory responses may not remarkably occur.Meanwhile,PM_(2.5)disturbed cAMP contents and key genes in the cAMP signaling pathway.The effects of PM_(2.5)of both regions were largely consistent,while Wangdu samples caused more ROS and Dianshan Lake samples tended to induce inflammatory injury.Thus,with the application of a novel ALI-based in vitro OEC model,our study demonstrated that ambient PM_(2.5)has the ability to threaten the physiologies and functions of the olfactory system.

Neurogenesis dynamics in the olfactory bulb:deciphering circuitry organization, function, and adaptive plasticity

Adult neurogenesis persists after birth in the subventricular zone, with new neurons migrating to the granule cell layer and glomerular layers of the olfactory bulb, where they integrate into existing circuitry as inhibitory interneurons. The generation of these new neurons in the olfactory bulb supports both structural and functional plasticity, aiding in circuit remodeling triggered by memory and learning processes. However, the presence of these neurons, coupled with the cellular diversity within the olfactory bulb, presents an ongoing challenge in understanding its network organization and function. Moreover,the continuous integration of new neurons in the olfactory bulb plays a pivotal role in regulating olfactory information processing. This adaptive process responds to changes in epithelial composition and contributes to the formation of olfactory memories by modulating cellular connectivity within the olfactory bulb and interacting intricately with higher-order brain regions. The role of adult neurogenesis in olfactory bulb functions remains a topic of debate. Nevertheless, the functionality of the olfactory bulb is intricately linked to the organization of granule cells around mitral and tufted cells. This organizational pattern significantly impacts output, network behavior, and synaptic plasticity, which are crucial for olfactory perception and memory. Additionally, this organization is further shaped by axon terminals originating from cortical and subcortical regions. Despite the crucial role of olfactory bulb in brain functions and behaviors related to olfaction, these complex and highly interconnected processes have not been comprehensively studied as a whole. Therefore, this manuscript aims to discuss our current understanding and explore how neural plasticity and olfactory neurogenesis contribute to enhancing the adaptability of the olfactory system. These mechanisms are thought to support olfactory learning and memory, potentially through increased complexity and restructuring of neural network structures, as well as the addition of new granule granule cells that aid in olfactory adaptation. Additionally, the manuscript underscores the importance of employing precise methodologies to elucidate the specific roles of adult neurogenesis amidst conflicting data and varying experimental paradigms. Understanding these processes is essential for gaining insights into the complexities of olfactory function and behavior.

Differential response of injured and healthy retinas to syngeneic and allogeneic transplantation of a clonal cell line of immortalized olfactory ensheathing glia:a double-edged sword

Olfactory ensheathing glia promote axonal regeneration in the mammalian central nervous system,including retinal ganglion cell axonal growth through the injured optic nerve.Still,it is unknown whether olfactory ensheathing glia also have neuroprotective properties.Olfactory ensheathing glia express brain-derived neurotrophic factor,one of the best neuroprotectants for axotomized retinal ganglion cells.Therefore,we aimed to investigate the neuroprotective capacity of olfactory ensheating glia after optic nerve crush.Olfactory ensheathing glia cells from an established rat immortalized clonal cell line,TEG3,were intravitreally injected in intact and axotomized retinas in syngeneic and allogeneic mode with or without microglial inhibition or immunosuppressive treatments.Anatomical and gene expression analyses were performed.Olfactory bulb-derived primary olfactory ensheathing glia and TEG3 express major histocompatibility complex classⅡmolecules.Allogeneically and syngenically transplanted TEG3 cells survived in the vitreous for up to 21 days,forming an epimembrane.In axotomized retinas,only the allogeneic TEG3 transplant rescued retinal ganglion cells at 7 days but not at 21 days.In these retinas,microglial anatomical activation was higher than after optic nerve crush alone.In intact retinas,both transplants activated microglial cells and caused retinal ganglion cell death at 21 days,a loss that was higher after allotransplantation,triggered by pyroptosis and partially rescued by microglial inhibition or immunosuppression.However,neuroprotection of axotomized retinal ganglion cells did not improve with these treatments.The different neuroprotective properties,different toxic effects,and different responses to microglial inhibitory treatments of olfactory ensheathing glia in the retina depending on the type of transplant highlight the importance of thorough preclinical studies to explore these variables.

Treadmill exercise in combination with acousto-optic and olfactory stimulation improves cognitive function in APP/PS1 mice through the brain-derived neurotrophic factor-and Cygb-associated signaling pathways

A reduction in adult neurogenesis is associated with behavioral abnormalities in patients with Alzheimer's disease.Consequently,enhancing adult neurogenesis represents a promising therapeutic approach for mitigating disease symptoms and progression.Nonetheless,nonpharmacological interventions aimed at inducing adult neurogenesis are currently limited.Although individual non-pharmacological interventions,such as aerobic exercise,acousto-optic stimulation,and olfactory stimulation,have shown limited capacity to improve neurogenesis and cognitive function in patients with Alzheimer's disease,the therapeutic effect of a strategy that combines these interventions has not been fully explored.In this study,we observed an age-dependent decrease in adult neurogenesis and a concurrent increase in amyloid-beta accumulation in the hippocampus of amyloid precursor protein/presenilin 1 mice aged 2-8 months.Amyloid deposition became evident at 4 months,while neurogenesis declined by 6 months,further deteriorating as the disease progressed.However,following a 4-week multifactor stimulation protocol,which encompassed treadmill running(46 min/d,10 m/min,6 days per week),40 Hz acousto-optic stimulation(1 hour/day,6 days/week),and olfactory stimulation(1 hour/day,6 days/week),we found a significant increase in the number of newborn cells(5'-bromo-2'-deoxyuridine-positive cells),immature neurons(doublecortin-positive cells),newborn immature neurons(5'-bromo-2'-deoxyuridine-positive/doublecortin-positive cells),and newborn astrocytes(5'-bromo-2'-deoxyuridine-positive/glial fibrillary acidic protein-positive cells).Additionally,the amyloid-beta load in the hippocampus decreased.These findings suggest that multifactor stimulation can enhance adult hippocampal neurogenesis and mitigate amyloid-beta neuropathology in amyloid precursor protein/presenilin 1 mice.Furthermore,cognitive abilities were improved,and depressive symptoms were alleviated in amyloid precursor protein/presenilin 1 mice following multifactor stimulation,as evidenced by Morris water maze,novel object recognition,forced swimming test,and tail suspension test results.Notably,the efficacy of multifactor stimulation in consolidating immature neurons persisted for at least 2weeks after treatment cessation.At the molecular level,multifactor stimulation upregulated the expression of neuron-related proteins(NeuN,doublecortin,postsynaptic density protein-95,and synaptophysin),anti-apoptosis-related proteins(Bcl-2 and PARP),and an autophagyassociated protein(LC3B),while decreasing the expression of apoptosis-related proteins(BAX and caspase-9),in the hippocampus of amyloid precursor protein/presenilin 1 mice.These observations might be attributable to both the brain-derived neurotrophic factor-mediated signaling pathway and antioxidant pathways.Furthermore,serum metabolomics analysis indicated that multifactor stimulation regulated differentially expressed metabolites associated with cell apoptosis,oxidative damage,and cognition.Collectively,these findings suggest that multifactor stimulation is a novel non-invasive approach for the prevention and treatment of Alzheimer's disease.

Progress in Research on Insect Olfactory Perception of Habitat Odor Molecules

A highly sensitive olfactory system allows insects to precisely identify and position volatile compounds from different sources in their habitats,and plays a crucial role in their foraging,mating,and oviposition activities.During evolution,insects have successfully developed a large and complex olfactory system to adapt to heterogeneous environments,enabling the maintenance of inset population.A comprehensive examination of the olfactory system of insects may therefore yield novel insights into the development of innovative pest control and prevention strategies,as well as the study of olfactory mechanisms in vertebrates and even humans.This paper outlines the current state of research into the signal transduction mechanism by which insects perceive the olfactory molecules of their habitats.The aim of this review is to provide a reference point for future studies into the olfactory perception mechanism and its potential applications in pest management.

The underlying mechanism of prodromal PD:insights from the parasympathetic nervous system and the olfactory system

Neurodegeneration of Parkinson’s disease(PD)starts in an insidious manner,30–50%of dopaminergic neurons have been lost in the substantia nigra before clinical diagnosis.Prodromal stage of the disease,during which the disease pathology has started but is insufficient to result in clinical manifestations,offers a valuable window for disease-modifying therapies.The most focused underlying mechanisms linking the pathological pattern and clinical characteristics of prodromal PD are the prion hypothesis of alpha-synuclein and the selective vulnerability of neurons.In this review,we consider the two potential portals,the vagus nerve and the olfactory bulb,through which abnormal alpha-synuclein can access the brain.We review the clinical,pathological and neuroimaging evidence of the parasympathetic nervous system and the olfactory system in the neurodegenerative process and using the two systems as models to discuss the internal homogeneity and heterogeneity of the prodromal stage of PD,including both the clustering and subtyping of symptoms and signs.Finally,we offer some suggestions on future directions for imaging studies in prodromal Parkinson’s disease.

Effects of combined acupuncture and eugenol on learning-memory ability and antioxidation system of hippocampus in Alzheimer disease rats via olfactory system stimulation

OBJECTIVE: To investigate the effects of combined acupuncture and eugenol on learning-memory ability and the antioxidation system of the hippocampus in Alzheimer disease (AD) rats. METHODS: Sixty Sprague Dawley rats, weighing (300±10) g, were randomly divided with 10 rats per group into a normal control group, AD model group, AD with cut olfactory nerve group, Xiu three-needle group, eugenol group, and combined acupuncture and eugenol group. The AD model was established by injection of amyloid β1-40 (Aβ 1-40). Morris maze tests were conducted for evaluating the learning-memory ability. Content of malo- ndialdehyde (MDA) and activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in the hippocampus were detected. RESULTS: The average escape latency and the mean swimming distance in the normal control group, the Xiu three-needle group, the eugenol group, and the combined acupuncture and euge-nol group were significantly shorter than those in the AD model group (all P<0.01). The combined acupuncture and eugenol group had shorter escape latency and mean swimming distance than those in the Xiu three-needle group and the eugenol group. There were no significant differences between the Xiu three-needle group and the eugenol group and between the AD group and the AD with cut olfactory nerve group (P>0.05). Compared with the normal control group, the MDA content in the hippocampus significantly increased (P<0.05) and GSH-Px and SOD activities significantly decreased in the AD model group (P<0.01). Compared with the AD model group, significantly decreased (P< 0.01) and SOD and GSH-Px activities significantly increased in the Xiu three-needle group, eugenol group, and combined acupuncture and eugenol group (P<0.05). Compared with the Xiu three-needle group and eugenol group, the MDA content significantly decreased (P<0.05) and SOD and GSH-Px activities increased (P<0.05) in the combined acupuncture and eugenol group. There were no significant differences among the three indices between the Xiu three-needle group and the eugenol group and between the AD model group and the AD with cut olfactory nerve group (P>0.05). CONCLUSION: Both Xiu three-needle and eugenol can increase learning-memory ability, decrease MDA content, and increase SOD and GSH-Px activities in the hippocampus in AD rats. The combination of acupuncture with eugenol has stronger effects, and the effects depend on the olfactory pathway.

The human olfactory system in two proteinopathies: Alzheimer’s and Parkinson’s diseases

Alzheimer’s and Parkinson’s diseases are the most prevalent neurodegenerative disorders.Their etiologies are idiopathic,and treatments are symptomatic and orientated towards cognitive or motor deficits.Neuropathologically,both are proteinopathies with pathological aggregates(plaques of amyloid-β peptide and neurofibrillary tangles of tau protein in Alzheimer’s disease,and Lewy bodies mostly composed of α-synuclein in Parkinson’s disease).These deposits appear in the nervous system in a predictable and accumulative sequence with six neuropathological stages.Both disorders present a long prodromal period,characterized by preclinical signs including hyposmia.Interestingly,the olfactory system,particularly the anterior olfactory nucleus,is initially and preferentially affected by the pathology.Cerebral atrophy revealed by magnetic resonance imaging must be complemented by histological analyses to ascertain whether neuronal and/or glial loss or neuropil remodeling are responsible for volumetric changes.It has been proposed that these proteinopathies could act in a prion-like manner in which a misfolded protein would be able to force native proteins into pathogenic folding(seeding),which then propagates through neurons and glia(spreading).Existing data have been examined to establish why some neuronal populations are vulnerable while others are resistant to pathology and to what extent glia prevent and/or facilitate proteinopathy spreading.Connectomic approaches reveal a number of hubs in the olfactory system(anterior olfactory nucleus,olfactory entorhinal cortex and cortical amygdala)that are key interconnectors with the main hubs(the entorhinal–hippocampal–cortical and amygdala–dorsal motor vagal nucleus)of network dysfunction in Alzheimer’s and Parkinson’s diseases.

Study of a Bionic Pattern Classifier Based on Olfactory Neural System

Simulating biological olfactory neural system, KⅢnetwork, which is a high-dimensional chaotic neural network, is designed in this paper. Different from conventional artificial neural network, the KⅢnetwork works in its chaotic trajectory. It can simulate not only the output EEG waveform observed in electrophysiological experiments, but also the biological intelligence for pattern classification. The simulation analysis and application to the recognition of handwriting numerals are presented here. The classification performance of the KⅢnetwork at different noise levels was also investigated.

Magnetic Resonance Imaging Findings of Olfactory Bulb in Anosmic Patients with COVID-19: A Systematic Review

Background Anosmia is one of the symptoms in individuals with SARS-CoV-2 infection.In anosmic patients,SARS-CoV-2 temporarily alters the signaling process in olfactory nerve cells and olfactory bulb(OB),which eventually damages the structure of the olfactory epithelium,leading to a permanent disorder in the olfactory pathway that this damaged structure is showed in MRI imaging Method Two investigators independently searched four databases consisting of PubMed,ProQuest,Scopus,and Web of Science for relevant records as of November 11,2020 with no time,space,and language restrictions.Google Scholar was also searched for the related resources within the time limit of 2020.All the found articles were reviewed based on the PRISMA flow diagram.Qualitative studies,case reports,editorials,letters,and other non-original studies were excluded from this systematic analysis.Results Initial search yielded 434 records.After reviewing the titles and abstracts,we selected 74 articles;finally,8 articles were depicted to be investigated and read in full text.The obtained results showed an increase in the width and volume of the olfactory cleft(OC),complete or partial destruction of OC,and complete occlusion of OC in COVID-19 patients.Deformation and degeneration as well as a subtle asymmetry were evident in the OBs.Computed tomography(CT),meganetic resonance imaging(MRI),and positron emission tomography(PET)were used to detect the outcomes of anosmia in these studies.Conclusions The changes in OC are greater than those in OB in patients with COVID-19,mainly due to the inflammatory and immune responses in OC.However,fewer changes in OB are due to neurological or vascular disorders.Topical steroid therapy and topical saline can be helpful.

Engineered olfactory system for in vitro artificial nose

The engineered biomimetic sensors can not only realize the action of organs,but also combine functional materials as in vitro organs by simulating the response of biological organs to different environmental signals.Artificial nose is a concept proposed by imitating biological olfactory system,simulating olfactory nerve cells,olfactory bulb and olfactory cortex through different materials to realize olfactory function.The sensor array used to sense external gas stimulation can be analyzed based on different recognition principles through different original signals such as optics,electricity,electrochemistry and bioelectricity.Furthermore,combined with pattern recognition and microarray technology,artificial nose can be highly integrated with biocompatible and other important properties to achieve in vitro application.The design principle and necessary components of artificial nose are introduced in this paper including sensing structure,recognition system and functional module.At the same time,the potential development prospects of molecular recognition technology,polymer-based materials and microarray integration in artificial nose are prospected.

Roles of the main olfactory and vomeronasal systems in the detection of androstenone in inbred strains of mice

We investigated the role of the main olfactory and accessory olfactory systems （MOS and AOS respectively） in the detection of androstenone. We used the following experimental approaches： behavioral, surgical removal of the vomeronasal organ （VNX） followed by histochemical verification and Fos immunohistochemistry. Using a Y-maze paradigm we estimated sensitivity of NZB/B1NJ and CBA/J mice to androstenone. CBA mice were 2,000-fold more sensitive to androstenone than NZB mice. VNX caused a 4-tol6-fold decrease in sensitivity to androstenone in highly-sensitive CBA mice, but did not affect thresholds in NZB mice. Results indicate the involvement of the MOS and AOS in the detection of androstenone. We observed a specific pattern of Fos-positive cells in the main olfactory bulb of CBA mice but not in NZB mice subsequent to exposure of mice to androstenone; the compound activated cells in the accessory olfactory bulb in both strains of mice, indicating the involvement of the vomeronasal organ. Patterns of Fos-positive cells in the vomeronasal organ were recorded subsequent to exposure to androstenone. Fos-positive receptor cells in the vomeronasal organ of CBA and NZB mice were different, in CBA mice Fos-positive cells were noted in both the basal and apical zones, however, in NZB mice activation was observed only in the apical zone [Current Zoology 56 （6）： 813-818, 2010].

Acupuncture for olfactory dysfunction in infected COVID-19 patients:Study protocol for a randomized,sham-controlled clinical trial

Background:Olfactory dysfunction(OD)is a common symptom of Corona Virus Disease 2019(COVID-19).It is defined as the reduced or distorted ability to smell during sniffing(orthonasal olfaction)and represents one of the early symptoms in the clinical course of COVID-19 infection.A large online questionnaire-based survey has shown that some post-COVID-19 patients had no improvement 1 month after discharge from the hospital.Objective:To explore the efficacy of acupuncture for OD in COVID-19 infected patients and to determine whether acupuncture could have benefits over sham acupuncture for OD in post-COVID-19 patients.Methods:This is a single-blind,randomized controlled,cross-over trial.We plan to recruit 40 post-COVID-19 patients with smell loss or smell distortions lasting for more than 1 month.Qualified patients will be randomly allocated to the intervention group(real acupuncture)or the control group(sham acupuncture)at a 1:1 ratio.Each patient will receive 8 sessions of treatment over 4 weeks(Cycle 1)and a 2-week follow-up.After the follow-up,the control group will be subjected to real acupuncture for another 4 weeks(Cycle 2),and the real acupuncture group will undergo the 4-week sham acupuncture.The primary outcomes will be the score changes on the questionnaire of olfactory functioning and olfaction-related quality of life at week 6,8,12,and 14 from the baseline.The secondary outcomes will be the changes in the olfactory test score at week 6 and 12 from the baseline measured by using the Traditional Chinese version of the University of Pennsylvania Smell Identification Test(UPSIT-TC).Discussion:The results of this trial will help to determine the effectiveness of acupuncture for OD in post-COVID-19 patients.This may provide a new treatment option for patients.

Prospects for the use of olfactory mucosa cells in bioprinting for the treatment of spinal cord injuries

The review focuses on the most important areas of cell therapy for spinal cord injuries.Olfactory mucosa cells are promising for transplantation.Obtaining these cells is safe for patients.The use of olfactory mucosa cells is effective in restoring motor function due to the remyelination and regeneration of axons after spinal cord injuries.These cells express neurotrophic factors that play an important role in the functional recovery of nerve tissue after spinal cord injuries.In addition,it is possible to increase the content of neurotrophic factors,at the site of injury,exogenously by the direct injection of neurotrophic factors or their delivery using gene therapy.The advantages of olfactory mucosa cells,in combination with neurotrophic factors,open up wide possibilities for their application in threedimensional and four-dimensional bioprinting technology treating spinal cord injuries.

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

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