Long-term Neurological Dysfunction Research Articles

When bones deceive: Beyond skeletal dysplasia

Congenital hypothyroidism results from a partial or complete loss of thyroid function. It is the most common treatable cause of mental retardation. Thyroid hormone facilitates the growth and development of the skeleton through its direct effects on chondrocyte proliferation and differentiation and its permissive effects on the growth hormone. Due to the congenital hypothyroidism screening programs, congenital hypothyroidism is rare, and hence, other differential diagnoses are often considered in children presenting later in life with short stature and coarse facies such as storage disorders, genetic disorders, and skeletal dysplasia. This article aims to assess and discuss the value of radiology, especially plain radiography and ultrasonography in the diagnosis of congenital hypothyroidism and prevent long-term mental retardation and neurological dysfunction.

Neuroprotectant Activity of Novel Water-Soluble Synthetic Neurosteroids on Organophosphate Intoxication and Status Epilepticus-Induced Long-Term Neurological Dysfunction, Neurodegeneration, and Neuroinflammation.

Organophosphates (OPs) and nerve agents are potent neurotoxic compounds that cause seizures, status epilepticus (SE), brain injury, or death. There are persistent long-term neurologic and neurodegenerative effects that manifest months to years after the initial exposure. Current antidotes are ineffective in preventing these long-term neurobehavioral and neuropathological changes. Additionally, there are few effective neuroprotectants for mitigating the long-term effects of acute OP intoxication. We have pioneered neurosteroids as novel anticonvulsants and neuroprotectants for OP intoxication and seizures. In this study, we evaluated the efficacy of two novel synthetic, water-soluble neurosteroids, valaxanolone (VX) and lysaxanolone (LX), in combating the long-term behavioral and neuropathological impairments caused by acute OP intoxication and SE. Animals were exposed to the OP nerve agent surrogate diisopropylfluorophosphate (DFP) and were treated with VX or LX in addition to midazolam at 40 minutes postexposure. The extent of neurodegeneration, along with various behavioral and memory deficits, were assessed at 3 months postexposure. VX significantly reduced deficits of aggressive behavior, anxiety, memory, and depressive-like traits in control (DFP-exposed, midazolam-treated) animals; VX also significantly prevented the DFP-induced chronic loss of NeuN(+) principal neurons and PV(+) inhibitory neurons in the hippocampus and other regions. Additionally, VX-treated animals exhibited a reduced inflammatory response with decreased GFAP(+) astrogliosis and IBA1(+) microgliosis in the hippocampus, amygdala, and other regions. Similarly, LX showed significant improvement in behavioral and memory deficits, and reduced neurodegeneration and cellular neuroinflammation. Together, these results demonstrate the neuroprotectant effects of the novel synthetic neurosteroids in mitigating the long-term neurologic dysfunction and neurodegeneration associated with OP exposure. SIGNIFICANCE STATEMENT: Survivors of nerve agents and organophosphate (OP) exposures suffer from long-term neurological deficits. Currently, there is no specific drug therapy for mitigating the impact of OP exposure. However, novel synthetic neurosteroids that activate tonic inhibition provide a viable option for treating OP intoxication. The data from this study indicates the neuroprotective effects of synthetic, water-soluble neurosteroids for attenuation of long-term neurological deficits after OP intoxication. These findings establish valaxanolone and lysaxanolone as potent and efficacious neuroprotectants suitable for injectable dosing.

Long-term neurological dysfunction associated with COVID-19: Lessons from influenza and inflammatory diseases?

As the COVID-19 pandemic persists, SARS-CoV-2 infection is increasingly associated with long-term neurological side effects including cognitive impairment, fatigue, depression, and anxiety, colloquially known as "long-COVID." While the full extent of long-COVID neuropathology across years or even decades is not yet known, we can perhaps take direction from long-standing research into other respiratory diseases, such as influenza, that can present with similar long-term neurological consequences. In this review, we highlight commonalities in the neurological impacts of influenza and COVID-19. We first focus on the common potential mechanisms underlying neurological sequelae of long-COVID and influenza, namely (1) viral neurotropism and (2) dysregulated peripheral inflammation. The latter, namely heightened peripheral inflammation leading to central nervous system dysfunction, is emerging as a shared mechanism in various peripheral inflammatory or inflammation-associated diseases and conditions. We then discuss historical and modern examples of influenza- and COVID-19-associated cognitive impairment, depression, anxiety, and fatigue, revealing key similarities in their neurological sequelae. Although we are learning that the effects of influenza and COVID differ somewhat in terms of their influence on the brain, as the impacts of long-COVID grow, such comparisons will likely prove valuable in guiding ongoing research into long-COVID, and perhaps foreshadow what could be in store for individuals with COVID-19 and their brain health.

A Pediatric Rat Model of Organophosphate-Induced Refractory Status Epilepticus: Characterization of Long-Term Epileptic Seizure Activity, Neurologic Dysfunction and Neurodegeneration.

Children are highly vulnerable to the neurotoxic effects of organophosphates (OPs), which can cause neuronal developmental defects, including intellectual disability, autism, epilepsy, and related comorbidities. Unfortunately, no specific pediatric OP neurotoxicity model currently exists. In this study, we developed and characterized a pediatric rat model of status epilepticus (SE) induced by the OP diisopropylfluorophosphate (DFP) and examined its impact on long-term neurological outcomes. Postnatal day 21 rats were exposed to a DFP regimen with standard antidotes. Progressive behavioral deteriorations were assessed over a three-month period. Development of epileptic seizures, ictal discharges, high-frequency oscillations (HFOs), and interictal spikes were monitored by video-electroencephalography recordings. Histology-stereology analysis was performed to assess neurodegeneration, neuroinflammation, and morphologic abnormalities. DFP-exposed, post-SE animals exhibited significantly elevated levels of anxiety and depression than age-matched controls at 1, 2, and 3 months post-exposure. DFP-exposed animals displayed aggressive behavior and a marked decline in object recognition memory, as well as prominent impairment in spatial learning and memory. DFP-exposed animals had striking electrographic abnormalities with the occurrence of displayed epileptic seizures, ictal discharges, HFOs, and interictal spikes, suggesting chronic epilepsy. Neuropathological analysis showed substantially fewer principal neurons and inhibitory interneurons with a marked increase in reactive microglia and neuroinflammation in the hippocampus and other brain regions. DFP-exposed animals also exhibited mossy fiber sprouting indicating impaired network formations. Long-term epileptic seizures and neuropsychiatric functional deficits induced by DFP were consistent with neuropathological defects. Collectively, this pediatric model displays many hallmarks of chronic sequelae reminiscent of children exposed to OPs, suggesting that it will be a valuable tool for investigating pathologic mechanisms and potential treatment strategies to attenuate long-term OP neurotoxicity. SIGNIFICANCE STATEMENT: Millions of children are exposed to organophosphates (OPs) used in agriculture or chemical incidents. This study investigated the long-term impact of neonatal exposure to the OP chemical diisopropylfluorophosphate (DFP) on neurobehavioral and neurodevelopmental outcomes in adulthood. DFP exposure caused long-lasting behavioral abnormalities, epileptic seizures, and bilateral brain defects with an array of neurological sequelae seen in children's OP neurotoxicity. Thus, this model provides a novel tool to explore therapeutic interventions that mitigate long-term neurotoxic effects of children exposed to OP-induced seizures and status epilepticus.

Neurosteroids as Novel Anticonvulsants for Refractory Status Epilepticus and Medical Countermeasures for Nerve Agents: A 15-Year Journey to Bring Ganaxolone from Bench to Clinic.

This article describes recent advances in the use of neurosteroids as novel anticonvulsants for refractory status epilepticus (RSE) and as medical countermeasures (MCs) for organophosphates and chemical nerve agents (OPNAs). We highlight a comprehensive 15-year journey to bring the synthetic neurosteroid ganaxolone (GX) from bench to clinic. RSE, including when caused by nerve agents, is associated with devastating morbidity and permanent long-term neurologic dysfunction. Although recent approval of benzodiazepines such as intranasal midazolam and intranasal midazolam offers improved control of acute seizures, novel anticonvulsants are needed to suppress RSE and improve neurologic function outcomes. Currently, few anticonvulsant MCs exist for victims of OPNA exposure and RSE. Standard-of-care MCs for postexposure treatment include benzodiazepines, which do not effectively prevent or mitigate seizures resulting from nerve agent intoxication, leaving an urgent unmet medical need for new anticonvulsants for RSE. Recently, we pioneered neurosteroids as next-generation anticonvulsants that are superior to benzodiazepines for treatment of OPNA intoxication and RSE. Because GX and related neurosteroids that activate extrasynaptic GABA-A receptors rapidly control seizures and offer robust neuroprotection by reducing neuronal damage and neuroinflammation, they effectively improve neurologic outcomes after acute OPNA exposure and RSE. GX has been selected for advanced, Biomedical Advanced Research and Development Authority-supported phase 3 trials of RSE and nerve agent seizures. In addition, in mechanistic studies of neurosteroids at extrasynaptic receptors, we identified novel synthetic analogs with features that are superior to GX for current medical needs. Development of new MCs for RSE is complex, tedious, and uncertain due to scientific and regulatory challenges. Thus, further research will be critical to fill key gaps in evaluating RSE and anticonvulsants in vulnerable (pediatric and geriatric) populations and military persons. SIGNIFICANCE STATEMENT: Following organophosphate and nerve agent intoxication, refractory status epilepticus (RSE) occurs despite benzodiazepine treatment. RSE occurs in 40% of status epilepticus patients, with a 35% mortality rate and significant neurological morbidity in survivors. To treat RSE, neurosteroids are better anticonvulsants than benzodiazepines. Our pioneering use of neurosteroids for RSE and nerve agents led us to develop ganaxolone as a novel anticonvulsant and neuroprotectant with significantly improved neurological outcomes. This article describes the bench-to-bedside journey of bringing neurosteroid therapy to patients, with ganaxolone leading the way.

Vagus nerve stimulation in cerebral stroke: biological mechanisms, therapeutic modalities, clinical applications, and future directions.

Stroke is a major disorder of the central nervous system that poses a serious threat to human life and quality of life. Many stroke victims are left with long-term neurological dysfunction, which adversely affects the well-being of the individual and the broader socioeconomic impact. Currently, post-stroke brain dysfunction is a major and difficult area of treatment. Vagus nerve stimulation is a Food and Drug Administration-approved exploratory treatment option for autism, refractory depression, epilepsy, and Alzheimer's disease. It is expected to be a novel therapeutic technique for the treatment of stroke owing to its association with multiple mechanisms such as altering neurotransmitters and the plasticity of central neurons. In animal models of acute ischemic stroke, vagus nerve stimulation has been shown to reduce infarct size, reduce post-stroke neurological damage, and improve learning and memory capacity in rats with stroke by reducing the inflammatory response, regulating blood-brain barrier permeability, and promoting angiogenesis and neurogenesis. At present, vagus nerve stimulation includes both invasive and non-invasive vagus nerve stimulation. Clinical studies have found that invasive vagus nerve stimulation combined with rehabilitation therapy is effective in improving upper limb motor and cognitive abilities in stroke patients. Further clinical studies have shown that non-invasive vagus nerve stimulation, including ear/cervical vagus nerve stimulation, can stimulate vagal projections to the central nervous system similarly to invasive vagus nerve stimulation and can have the same effect. In this paper, we first describe the multiple effects of vagus nerve stimulation in stroke, and then discuss in depth its neuroprotective mechanisms in ischemic stroke. We go on to outline the results of the current major clinical applications of invasive and non-invasive vagus nerve stimulation. Finally, we provide a more comprehensive evaluation of the advantages and disadvantages of different types of vagus nerve stimulation in the treatment of cerebral ischemia and provide an outlook on the developmental trends. We believe that vagus nerve stimulation, as an effective treatment for stroke, will be widely used in clinical practice to promote the recovery of stroke patients and reduce the incidence of disability.

A modified murine photothrombotic stroke model: a minimally invasive and reproducible cortical and sub-cortical infarct volume and long-term deficits.

Ischemic stroke is one of the major causes of devastating neurological disabilities and mortality worldwide. Despite extensive research for treatment approaches, there remains limited therapy in the stroke field. Therefore, more research is required for reproducibility to understand stroke pathology in pre-clinical studies. In the current modified method, mice were subjected to photothrombotic stroke (pt-MCA; proximal-middle cerebral artery was exposed with a 532nm laser beam for 4min) by retro-orbital injection of photosensitive dye, Rose Bengal (15mg/kg) before the laser light exposure. Sensorimotor deficits were assessed by rotarod and catwalk test at 72h following post-pt-MCAO, and brain samples were collected for infarct volume and hemorrhagic transformation (HT) assessments. Cognitive impairments were assessed by a novel objective recognition and Morris's water maze tests at the end of the follow-up. pt-MCAO animals significantly reduced body weight and impaired motor and cognitive functions. Furthermore, pt-MCAO animals showed apparent infarction, brain edema, and increased HT compared to the sham animals. Additionally, this method enables concurrent measurement of short-term and long-term neurological dysfunction with relatively larger cortical and sub-cortical infarct volume following pt-MCAO. With respect to the other models, this modified model offers enhanced reproducibility regarding infarct volume and cognitive/functional outcomes and avoids complications associated with critical surgeries and craniotomy. In conclusion, this modified model helps to understand stroke pathogenesis and minimize the animals' numbers which help to increase the scientific and statistical potential in pre-clinical studies.

Admission Clinical and EEG Features Associated With Mortality and Long-term Neurologic and Cognitive Outcomes in Pediatric Cerebral Malaria.

For children with cerebral malaria, mortality is high, and in survivors, long-term neurologic and cognitive dysfunctions are common. While specific clinical factors are associated with death or long-term neurocognitive morbidity in cerebral malaria, the association of EEG features with these outcomes, particularly neurocognitive outcomes, is less well characterized. In this prospective cohort study of 149 children age 6 months to 12 years who survived cerebral malaria in Kampala, Uganda, we evaluated whether depth of coma, number of clinical seizures, or EEG features during hospitalization were associated with mortality during hospitalization, short-term and long-term neurologic deficits, or long-term cognitive outcomes (overall cognition, attention, memory) over the 2-year follow-up. Higher Blantyre or Glasgow Coma Scores (BCS and GCS, respectively), higher background voltage, and presence of normal reactivity on EEG were each associated with lower mortality. Among clinical and EEG features, the presence of >4 seizures on admission had the best combination of negative and positive predictive values for neurologic deficits in follow-up. In multivariable modeling of cognitive outcomes, the number of seizures and specific EEG features showed independent association with better outcomes. In children younger than 5 years throughout the study, seizure number and presence of vertex sharp waves were independently associated with better posthospitalization cognitive performance, faster dominant frequency with better attention, and higher average background voltage and faster dominant background frequency with better associative memory. In children younger than 5 years at CM episode but 5 years or older at cognitive testing, seizure number, background dominant frequency, and the presence of vertex sharp waves were each associated with changes in cognition, seizure number and variability with attention, and seizure number with working memory. In children with cerebral malaria, seizure number is strongly associated with the risk of long-term neurologic deficits, while seizure number and specific EEG features (average background voltage, dominant rhythm frequency, presence of vertex sharp waves, presence of variability) are independently associated with cognitive outcomes. Future studies should evaluate the predictive value of these findings.

Near-infrared-IIb fluorescent nanozymes for imaging-guided treatment of traumatic brain injury

Traumatic brain injury (TBI) often results in damage to the blood–brain barrier (BBB), leading to secondary effects such as neuroinflammation mediated by reactive oxygen species (ROS), which can increase the risk of long-term neurological dysfunction. Therefore, it is crucial to remove excessive ROS and monitor the status of BBB for timely clinical intervention. Here, we developed a fluorescent nanozyme by doping Mn atoms into PbS/CdS quantum dots (QDs) that emit in the near-infrared-II (NIR-IIb, 1500–1700 nm) region, enabling imaging-guided treatment of TBI. The QD-based nanozyme exhibited excellent antioxidant activity due to uniformly distributed Mn atoms on the surface, which effectively scavenged ROS and inhibited the release of pro-inflammatory factors, thus providing neuroprotective effects for TBI treatment. Additionally, the nanozyme demonstrated exceptional NIR-IIb fluorescence performance, allowing for dynamic monitoring of BBB status with high spatiotemporal resolution to guide precise TBI treatment.

Mild traumatic brain injury history is associated with lower brain network resilience in soldiers.

Special Operations Forces combat soldiers sustain frequent blast and blunt neurotrauma, most often classified as mild traumatic brain injuries. Exposure to repetitive mild traumatic brain injuries is associated with persistent behavioural, cognitive, emotional and neurological symptoms later in life. Identifying neurophysiological changes associated with mild traumatic brain injury exposure, in the absence of present-day symptoms, is necessary for detecting future neurological risk. Advancements in graph theory and functional MRI have offered novel ways to analyse complex whole-brain network connectivity. Our purpose was to determine how mild traumatic brain injury history, lifetime incidence and recency affected whole-brain graph theoretical outcome measures. Healthy male Special Operations Forces combat soldiers (age = 33.2 ± 4.3 years) underwent multimodal neuroimaging at a biomedical research imaging centre using 3T Siemens Prisma or Biograph MRI scanners in this cross-sectional study. Anatomical and functional scans were preprocessed. The blood-oxygen-level-dependent signal was extracted from each functional MRI time series using the Big Brain 300 atlas. Correlations between atlas regions were calculated and Fisher z-transformed to generate subject-level correlation matrices. The Brain Connectivity Toolbox was used to obtain functional network measures for global efficiency (the average inverse shortest path length), local efficiency (the average global efficiency of each node and its neighbours), and assortativity coefficient (the correlation coefficient between the degrees of all nodes on two opposite ends of a link). General linear models were fit to compare mild traumatic brain injury lifetime incidence and recency. Nonparametric ANOVAs were used for tests on non-normally distributed data. Soldiers with a history of mild traumatic brain injury had significantly lower assortativity than those who did not self-report mild traumatic brain injury (t148 = 2.44, P = 0.016). The assortativity coefficient was significantly predicted by continuous mild traumatic brain injury lifetime incidence [F1,144 = 6.51, P = 0.012]. No differences were observed between recency groups, and no global or local efficiency differences were observed between mild traumatic brain injury history and lifetime incidence groups. Brain networks with greater assortativity have more resilient, interconnected hubs, while those with lower assortativity indicate widely distributed, vulnerable hubs. Greater lifetime mild traumatic brain injury incidence predicted lower assortativity in our study sample. Less resilient brain networks may represent a lack of physiological recovery in mild traumatic brain injury patients, who otherwise demonstrate clinical recovery, more vulnerability to future brain injury and increased risk for accelerated age-related neurodegenerative changes. Future longitudinal studies should investigate whether decreased brain network resilience may be a predictor for long-term neurological dysfunction.

An Examination of Visual Quality of Life and Functional Vision Among Collision and Non-Collision Athletes Over a Competitive Season.

Repetitive head impacts (RHIs) experienced during sports are gaining attention due to potential long-term neurological dysfunction, absent of a diagnosed concussion. One area susceptible to dysfunction is vision. The goal of this study was to evaluate changes in visual quality of life (VQOL) and functional vision scores from pre- to post-season among collision and non-collision athletes. The Visual Functioning Questionnaire-25 and Neuro-Ophthalmic Supplement (NOS), as well as functional vision testing (Mobile Universal Lexicon Evaluation System - MULES) were completed pre- and post-season by three groups: collision athletes, non-collision athletes, and minimally active controls (MACs). There were 42 participants, with 41 (21 male, 20 female) completing both testing sessions, with a mean (standard deviation [SD]) age of 21 (2.46) years (collision group, n = 14; non-collision group, n = 13, MACs, n = 14). Baseline analyses revealed no significant differences between groups for VQOL or MULES scores. However, those with a family history of psychiatric disorder scored significantly worse on NOS. Post-season/follow-up testing revealed no significant differences between groups for VQOL scores. Non-collision athletes significantly improved on the MULES test by 2.46 ± 3.60 (SD) s (35.0 [95% confidence interval, 0.29-4.63]; p = .03). Change score results from pre- to post-season were not significant. Although the groups were not significantly different from one another, non-collision athletes significantly improved MULES scores, whereas collision athletes performed the worst, suggesting exposure to RHIs may impact functional vision. Thus, further evaluation of RHIs and their impact on vision is warranted.

Alpha-Asarone Ameliorates Neurological Dysfunction of Subarachnoid Hemorrhagic Rats in Both Acute and Recovery Phases via Regulating the CaMKII-Dependent Pathways.

Early brain injury (EBI) is the leading cause of poor prognosis for patients suffering from subarachnoid hemorrhage (SAH), particularly learning and memory deficits in the repair phase. A recent report has involved calcium/calmodulin-dependent protein kinase II (CaMKII) in the pathophysiological process underlying SAH-induced EBI. Alpha-asarone (ASA), a major compound isolated from the Chinese medicinal herb Acorus tatarinowii Schott, was proven to reduce secondary brain injury by decreasing CaMKII over-phosphorylation in rats' model of intracerebral hemorrhage in our previous report. However, the effect of ASA on SAH remains unclear, and the role of CaMKII in both acute and recovery stages of SAH needs further investigation. In this work, we first established a classic SAH rat model by endovascular perforation and intraperitoneally administrated different ASA doses (10, 20, and 40mg/kg) 2h after successful modeling. Then, the short- and long-term neurobehavioral performances were blindly evaluated to confirm ASA's efficacy against SAH. Subsequently, we explored ASA's therapeutic mechanism in both acute and recovery stages using histopathological examination, TUNEL staining, flow cytometry, Western-blot, double-immunofluorescence staining, and transmission electron microscopy (TEM) observation. Finally, KN93, a selective CaMKII inhibitor, was applied in oxyhemoglobin-damaged HT22 cells to explore the role of CaMKII in ASA's neuroprotective effect. The results demonstrated that ASA alleviated short- and long-term neurological dysfunction, reduced mortality and seizure rate within 24h, and prolonged 14-day survival in SAH rats. Histopathological examination showed a reduction of neuronal damage and a restoration of the hippocampal structure after ASA treatment in both acute and recovery phases of SAH. In the acute stage, the Western-blot and flow cytometer analyses showed that ASA restored E/I balance, reduced calcium overload and CaMKII phosphorylation, and inhibited mitochondrion-involved apoptosis, thus preventing neuronal damage and apoptosis underlying EBI post-SAH. In the recovery stage, the TEM observation, double-immunofluorescence staining, and Western-blot analyses indicated that ASA increased the numbers of synapses and enhanced synaptic plasticity in the ipsilateral hippocampi, probably by promoting NR2B/CaMKII interaction and activating subsequent CREB/BDNF/TrkB signaling pathways. Furthermore, KN93 notably reversed ASA's neuroprotective effect on oxyhemoglobin-damaged HT22 cells, confirming CaMKII a potential target for ASA's efficacy against SAH. Our study confirmed for the first time that ASA ameliorated the SAH rats' neurobehavioral deterioration, possibly via modulating CaMKII-involved pathways. These findings provided a promising candidate for the clinical treatment of SAH and shed light on future drug discovery against SAH.

Therapeutic Hypothermia Attenuates Cortical Interneuron Loss after Cerebral Ischemia in Near-Term Fetal Sheep.

Therapeutic hypothermia significantly improves outcomes after neonatal hypoxic-ischemic (HI) encephalopathy but is only partially protective. There is evidence that cortical inhibitory interneuron circuits are particularly vulnerable to HI and that loss of interneurons may be an important contributor to long-term neurological dysfunction in these infants. In the present study, we examined the hypothesis that the duration of hypothermia has differential effects on interneuron survival after HI. Near-term fetal sheep received sham ischemia or cerebral ischemia for 30 min, followed by cerebral hypothermia from 3 h after ischemia end and continued up to 48 h, 72 h, or 120 h recovery. Sheep were euthanized after 7 days for histology. Hypothermia up to 48 h recovery resulted in moderate neuroprotection of glutamate decarboxylase (GAD)+ and parvalbumin+ interneurons but did not improve survival of calbindin+ cells. Hypothermia up to 72 h recovery was associated with significantly increased survival of all three interneuron phenotypes compared with sham controls. By contrast, while hypothermia up to 120 h recovery did not further improve (or impair) GAD+ or parvalbumin+ neuronal survival compared with hypothermia up to 72 h, it was associated with decreased survival of calbindin+ interneurons. Finally, protection of parvalbumin+ and GAD+ interneurons, but not calbindin+ interneurons, with hypothermia was associated with improved recovery of electroencephalographic (EEG) power and frequency by day 7 after HI. The present study demonstrates differential effects of increasing the duration of hypothermia on interneuron survival after HI in near-term fetal sheep. These findings may contribute to the apparent preclinical and clinical lack of benefit of very prolonged hypothermia.

Baseline Gait and Motor Function Predict Long-Term Severity of Neurological Outcomes of Viral Infection.

Neurological dysfunction following viral infection varies among individuals, largely due to differences in their genetic backgrounds. Gait patterns, which can be evaluated using measures of coordination, balance, posture, muscle function, step-to-step variability, and other factors, are also influenced by genetic background. Accordingly, to some extent gait can be characteristic of an individual, even prior to changes in neurological function. Because neuromuscular aspects of gait are under a certain degree of genetic control, the hypothesis tested was that gait parameters could be predictive of neuromuscular dysfunction following viral infection. The Collaborative Cross (CC) mouse resource was utilized to model genetically diverse populations and the DigiGait treadmill system used to provide quantitative and objective measurements of 131 gait parameters in 142 mice from 23 CC and SJL/J strains. DigiGait measurements were taken prior to infection with the neurotropic virus Theiler's Murine Encephalomyelitis Virus (TMEV). Neurological phenotypes were recorded over 90 days post-infection (d.p.i.), and the cumulative frequency of the observation of these phenotypes was statistically associated with discrete baseline DigiGait measurements. These associations represented spatial and postural aspects of gait influenced by the 90 d.p.i. phenotype score. Furthermore, associations were found between these gait parameters with sex and outcomes considered to show resistance, resilience, or susceptibility to severe neurological symptoms after long-term infection. For example, higher pre-infection measurement values for the Paw Drag parameter corresponded with greater disease severity at 90 d.p.i. Quantitative trait loci significantly associated with these DigiGait parameters revealed potential relationships between 28 differentially expressed genes (DEGs) and different aspects of gait influenced by viral infection. Thus, these potential candidate genes and genetic variations may be predictive of long-term neurological dysfunction. Overall, these findings demonstrate the predictive/prognostic value of quantitative and objective pre-infection DigiGait measurements for viral-induced neuromuscular dysfunction.

Mitochondria-containing extracellular vesicles (EV) reduce mouse brain infarct sizes and EV/HSP27 protect ischemic brain endothelial cultures.

Ischemic stroke causes brain endothelial cell (BEC) death and damages tight junction integrity of the blood-brain barrier (BBB). We harnessed the innate mitochondrial load of BEC-derived extracellular vesicles (EVs) and utilized mixtures of EV/exogenous 27 kDa heat shock protein (HSP27) as a one-two punch strategy to increase BEC survival (via EV mitochondria) and preserve their tight junction integrity (via HSP27 effects). We demonstrated that the medium-to-large (m/lEV) but not small EVs (sEV) transferred their mitochondrial load, that subsequently colocalized with the mitochondrial network of the recipient primary human BECs. Recipient BECs treated with m/lEVs showed increased relative ATP levels and mitochondrial function. To determine if the m/lEV-meditated increase in recipient BEC ATP levels was associated with m/lEV mitochondria, we isolated m/lEVs from donor BECs pre-treated with oligomycin A (OGM, mitochondria electron transport complex V inhibitor), referred to as OGM-m/lEVs. BECs treated with naïve m/lEVs showed a significant increase in ATP levels compared to untreated OGD cells, OGM-m/lEVs treated BECs showed a loss of ATP levels suggesting that the m/lEV-mediated increase in ATP levels is likely a function of their innate mitochondrial load. In contrast, sEV-mediated ATP increases were not affected by inhibition of mitochondrial function in the donor BECs. Intravenously administered m/lEVs showed a reduction in brain infarct sizes compared to vehicle-injected mice in a mouse middle cerebral artery occlusion model of ischemic stroke. We formulated binary mixtures of human recombinant HSP27 protein with EVs: EV/HSP27 and ternary mixtures of HSP27 and EVs with a cationic polymer, poly (ethylene glycol)-b-poly (diethyltriamine): (PEG-DET/HSP27)/EV. (PEG-DET/HSP27)/EV and EV/HSP27 mixtures decreased the paracellular permeability of small and large molecular mass fluorescent tracers in oxygen glucose-deprived primary human BECs. This one-two punch approach to increase BEC metabolic function and tight junction integrity may be a promising strategy for BBB protection and prevention of long-term neurological dysfunction post-ischemic stroke.

Predictive value of neurophysiological monitoring during posterior communicating artery aneurysm clipping for postoperative neurological deficits.

This study aimed to evaluate the diagnostic effect of intraoperative neurophysiological monitoring in identifying intraoperative ischemic events and predicting postoperative neurological dysfunction during PCoA aneurysm clipping, as well as to explore the safe duration of intraoperative temporary clipping of the parent artery. All 71 patients with PCoA aneurysm underwent craniotomy and aneurysm clipping. MEP and SSEP were used for monitoring during operation to evaluate the influence of MEP/SSEP changes on postoperative neurological function. Receiver operating characteristic (ROC) curve analysis was used to calculate optimal duration of intraoperative temporary clipping. Patients with intraoperative MEP/SSEP changes were more likely to develop short-term and long-term neurological deficits than those without MEP/SSEP changes (P < 0.05). From the ROC curve analysis, the safe time from the initiation of temporary clipping during the operation to the early warning of neurophysiological monitoring was 4.5 min (AUC = 0.735, 95%CI 0.5558-0.912). Taking 4.5 min as the dividing line, the incidence of short-term and long-term neurological dysfunction in patients with temporary clipping >4.5 min was significantly higher than that in patients with temporary clipping ≤4.5 min (P = 0.015, P = 0.018). Intraoperative MEP/SSEP changes are significantly associated with postoperative neurological dysfunction in patients with PCoA aneurysms. The optimal duration of temporary clipping of the parent artery during posterior communicating aneurysm clipping was 4.5 min under neurophysiological monitoring.

Protective effect of isoflurane preconditioning on neurological function in rats with HIE.

Hypoxic-ischemic encephalopathy (HIE) is an important cause of neonatal death and disability, which can lead to long-term neurological and motor dysfunction. Currently, inhalation anesthetics are widely used in surgery, and some studies have found that isoflurane (ISO) may have a positive effect on neuroprotection. In this paper, we investigated whether ISO pretreatment has a neuroprotective effect on the neurological function of HIE rats. Here, 7-day-old neonatal rats were randomly divided into a sham group, a hypoxic-ischemic (HI) group, and an ISO pretreatment (pretreatment) group. The pretreatment group was pretreated with 2% ISO for 1 h, followed by the HI group to establish an HI animal model. The HI‑induced neurological injury was evaluated by Zea‑Longa scores and triphenyltetrazolium (TTC) staining. Neuronal number and histomorphological changes were observed with Nissl staining and Hematoxylin-eosin (HE) staining. In addition, motor learning memory function was evaluated by the Morris water maze (MWM), the Y-maze, and the rotarod tests. HI induced severe neurological dysfunction, brain infarction, and cell apoptosis as well as obvious neuron loss in neonatal rats. In the MWM, the rats in the pretreatment group showed a decrease in escape latency (p = 0.042), indicating that pretreatment with ISO could improve the learning ability of HI rats. The results of Nissl staining showed that in the HI group, there was an irregular arrangement of neurons and nuclear fixation; however, the cell damage was significantly reduced and the total number of neurons was increased after ISO pretreatment (p < 0.001). In conclusion, ISO pretreatment improved cognitive function and attenuated HI-induced reduction of Nissl-positive cells and spatial memory impairment, suggesting that pretreatment with ISO before HI modeling could reduce neuronal cell death in the hippocampus after HI.

Intermittent hypoxic conditioning restores neurological dysfunction of mice induced by long-term hypoxia.

Central nervous system diseases are associated with hypoxia, which usually cause irreversible nerve damage, but the underlying mechanism is unclear and effective intervention strategies are lacking. This study was designed to explore the mechanism and treatment strategy of hypoxia-induced nerve injury. In this study, 13% O2 was used to treat mice for 0, 1, 3 7, and 14 days, Morris water maze and other animal behavior experiments were used to evaluate the neurological function of mice. TUNEL, BrdU, PCNA, DCX, and SOX2 staining were used to observe the apoptosis and proliferation of mouse neurons. RT-PCR and Iba1 staining were used to evaluate the release of inflammatory factors IL-1β, IL-6, and TNF-α and the activation of microglia. Short-term hypoxia promotes neurogenesis, while long-term hypoxia inhibits neurogenesis. The changes in hypoxia-induced neurogenesis were positively correlated with neurological functions, but negatively correlated with apoptosis. Moreover, intermittent hypoxic conditioning restored long-term hypoxia-induced neurological dysfunction by promoting neural stem cell generation and inhibiting the release of inflammatory factors IL-1β, IL-6, and TNF-α and the activation of microglia. Hypoxia promoted neurogenesis in a time-dependent manner, and intermittent hypoxic conditioning exerted a neuroprotective effect through promoting neural stem cell generation and suppressing inflammation induced by long-term hypoxia stress, which provided a novel concept to develop a treatment for hypoxia-related brain injury.

Severe Neuro-COVID is associated with peripheral immune signatures, autoimmunity and neurodegeneration: a prospective cross-sectional study

Growing evidence links COVID-19 with acute and long-term neurological dysfunction. However, the pathophysiological mechanisms resulting in central nervous system involvement remain unclear, posing both diagnostic and therapeutic challenges. Here we show outcomes of a cross-sectional clinical study (NCT04472013) including clinical and imaging data and corresponding multidimensional characterization of immune mediators in the cerebrospinal fluid (CSF) and plasma of patients belonging to different Neuro-COVID severity classes. The most prominent signs of severe Neuro-COVID are blood-brain barrier (BBB) impairment, elevated microglia activation markers and a polyclonal B cell response targeting self-antigens and non-self-antigens. COVID-19 patients show decreased regional brain volumes associating with specific CSF parameters, however, COVID-19 patients characterized by plasma cytokine storm are presenting with a non-inflammatory CSF profile. Post-acute COVID-19 syndrome strongly associates with a distinctive set of CSF and plasma mediators. Collectively, we identify several potentially actionable targets to prevent or intervene with the neurological consequences of SARS-CoV-2 infection.

Modified exosomal SIRPα variants alleviate white matter injury after intracerebral hemorrhage via microglia/macrophages

BackgroundDespite limited efficiency, modulation of microglia/macrophages has shown to attenuate neuroinflammation after intracerebral hemorrhage (ICH). In this context, we evaluated the efficacy of modified exosomal signal regulatory protein α (SIRPα) variants (SIRPα-v Exos) in microglia/macrophages and neuroinflammation-associated white matter injury after ICH.MethodsSIRPα-v Exos were engineered to block CD47-SIRPα interactions. After obtaining SIRPα-v Exos from lentivirus-infected mesenchymal stem cells, C57BL/6 mice suffering from ICH underwent consecutive intravenous injections of SIRPα-v Exos (6 mg/kg) for 14 days. Afterwards, the volume of hematoma and neurological dysfunctions were assessed in mice continuously until 35 days after ICH. In addition, demyelination, electrophysiology and neuroinflammation were evaluated. Furthermore, the mechanisms of microglial regulation by SIRPα-v Exos were investigated in vitro under coculture conditions.ResultsThe results demonstrated that the clearance of hematoma in mice suffering from ICH was accelerated after SIRPα-v Exo treatment. SIRPα-v Exos improved long-term neurological dysfunction by ameliorating white matter injury. In addition, SIRPα-v Exos recruited regulatory T cells (Tregs) to promote M2 polarization of microglia/macrophages in the peri-hematoma tissue. In vitro experiments further showed that SIRPα-v Exos regulated primary microglia in a direct and indirect manner in synergy with Tregs.ConclusionOur studies revealed that SIRPα-v Exos could accelerate the clearance of hematoma and ameliorate secondary white matter injury after ICH through regulation of microglia/macrophages. SIRPα-v Exos may become a promising treatment for ICH in clinical practice.Graphical