Electrophysiological Assessment Research Articles

Aldosterone Robustly Promotes Atrial Fibrillation in the Presence of Chronic Volume Overload in Rats.

We investigated the modulatory effects of aldosterone on atrial remodeling induced by an abdominal aorto-venocaval shunt (AVS) in rats, as patients with primary hyperaldosteronism are suggested to have a higher risk of developing atrial fibrillation (AF). The rats were divided into four groups based on the basis of whether they underwent AVS surgery, received aldosterone using an intraperitoneally implanted osmotic minipump, or both. Aldosterone was started at 0.5 µg/h during the AVS surgery, and morphological and electrophysiological assessments were performed four weeks after AVS creation. The atrial structural changes induced by AVS, including atrial cell hypertrophy and fibrosis, were not modulated by aldosterone, whereas P-wave duration was longer in aldosterone-treated AVS rats than in non-treated rats. Although the average AF duration induced by burst pacing was 10-25 s in the untreated, aldosterone-treated, and AVS rats, the AF duration was approximately 100 s in the aldosterone-treated AVS rats. Meanwhile, there was no significant difference in the atrial effective refractory period among the four experimental groups. Notably, premature atrial contractions (PAC) were frequently observed in aldosterone-treated sham rats, while paroxysmal AF, in addition to PAC, was detected in aldosterone-treated AVS rats, which was not induced in non-treated AVS rats. These findings suggest that aldosterone robustly promotes AF, particularly in the presence of chronic volume overload.

Combined use of CLP290 and bumetanide alleviates neuropathic pain and its mechanism after spinal cord injury inrats.

We aimed to explore whether the combination of CLP290 and bumetanide maximally improves neuropathic pain following spinal cord injury (SCI) and its possible molecular mechanism. Rats were randomly divided into five groups: Sham, SCI + vehicle, SCI + CLP290, SCI + bumetanide, and SCI + combination (CLP290 + bumetanide). Drug administration commenced on the 7th day post-injury (7 dpi) and continued for 14 days. All rats underwent behavioral assessments for 56 days to comprehensively evaluate the effects of interventions on mechanical pain, thermal pain, cold pain, motor function, and other relevant parameters. Electrophysiological assessments, immunoblotting, and immunofluorescence detection were performed at different timepoints post-injury, with a specific focus on the expression and changes of KCC2 and NKCC1 proteins in the lumbar enlargement of the spinal cord. CLP290 and bumetanide alleviated SCI-associated hypersensitivity and locomotor function, with the combination providing enhanced recovery. The combined treatment group exhibited the most significant improvement in restoring Rate-Dependent Depression (RDD) levels. In the combined treatment group and the two individual drug administration groups, the upregulation of potassium chloride cotransporter 2 (K+-Cl-cotransporter 2, KCC2) expression and downregulation of sodium potassium chloride cotransporter 1 (Na+-K+-Cl-cotransporter 1, NKCC1) expression in the lumbar enlargement area resulted in a significant increase in the KCC2/NKCC1 ratio compared to the SCI + vehicle group, with the most pronounced improvement seen in the combined treatment group. Compared to the SCI + vehicle group, the SCI + bumetanide group showed no significant paw withdrawal thermal latency (PWTL) improvement at 21 and 35 dpi, but a notable enhancement at 56 dpi. In contrast, the SCI + CLP290 group significantly improved PWTL at 21 days, with non-significant changes at 35 and 56 days. At 21 dpi, KCC2 expression was marginally higher in monotherapy groups versus SCI + vehicle, but not significantly. At 56 dpi, only the SCI + bumetanide group showed a significant difference in KCC2 expression compared to the control group. Combined application of CLP290 and bumetanide effectively increases the ratio of KCC2/NKCC1, restores RDD levels, enhancesGABAA receptor-mediated inhibitory function in the spinal cord, and relieves neuropathic pain in SCI; Bumetanide significantly improves neuropathic pain in the long term, whereas CLP290 demonstrates a notable short-term effect.

Motor unit number index in Bell's palsy: A potential electrophysiological biomarker for early evaluation.

Reliable, noninvasive early diagnostics of neuromuscular function in Bell's palsy, which causes facial paralysis and reduced quality of life, remain to be established. Here, we aimed to evaluate the utility of the motor unit number index (MUNIX) for the quantitative electrophysiological assessment of early-stage Bell's palsy, its correlation with clinical assessments, changes following treatment, and association with clinical prognosis. MUNIX measures were recorded from the bilateral zygomaticus, orbicularis oculi, and orbicularis oris muscles of 10 healthy individuals and 64 patients with Bell's palsy. The patients were assessed by two specialist neurologists using the House-Brackmann and Sunnybrook Facial Grading Systems. Repeat assessments were performed on 20 patients with Bell's palsy who received treatment. Additionally, the 64 patients were reassessed using clinical scales after a 1-month interval. The MUNIX values of the main affected muscles on the affected side were lower than those on the healthy side in patients with Bell's palsy (p<.05). The MUNIX measurements significantly correlated with the clinical facial nerve palsy scale scores (p<.05). Significant improvements were observed in the MUNIX values on repeat testing following treatment (p<.05). The baseline motor unit size index (the compound muscle action potential amplitude divided by MUNIX) was positively associated with improved clinical presentation after 1 month (p<.05). MUNIX can be used as an electrophysiological biomarker for the quantitative assessment of facial nerve palsy and treatment response, and as a prognostic biomarker, in patients with early Bell's palsy, and is recommended as a complement to conventional neurophysiological examinations.

An essential role for the latero-medial secondary visual cortex in the acquisition and retention of visual perceptual learning in mice

Perceptual learning refers to any change in discrimination abilities as a result of practice, a fundamental process that improves the organism’s response to the external environment. Visual perceptual learning (vPL) is supposed to rely on functional rearrangements in brain circuity occurring at early stages of sensory processing, with a pivotal role for the primary visual cortex (V1). However, top-down inputs from higher-order visual areas (HVAs) have been suggested to play a key part in vPL, conveying information on attention, expectation and the precise nature of the perceptual task. A direct assessment of the possibility to modulate vPL by manipulating top-down activity in awake subjects is still missing. Here, we used a combination of chemogenetics, behavioral analysis and multichannel electrophysiological assessments to show a critical role in vPL acquisition and retention for neuronal activity in the latero-medial secondary visual cortex (LM), the prime source for top-down feedback projections reentering V1.

Pain hypersensitivity, sensorimotor impairment, and decreased muscle force in a novel rat model of radiation-induced peripheral neuropathy.

Radiation-induced peripheral neuropathy is a rare, but serious complication often resulting in profound morbidity, life-long disability, and chronic debilitating pain. Unfortunately, this type of peripheral neuropathy is usually progressive, and almost always irreversible. To date, a standardized rat model of radiation-induced peripheral neuropathy has not been established. The purpose of the present study was to examine neuropathic pain, sensorimotor impairment, and muscle force parameters following the administration of a clinically relevant radiation dose in a rat model. Ten rats were randomly assigned to one of two experimental groups: (1) radiation and (2) sham-radiated controls. Radiated animals were given a clinically relevant dose of 35 Gray (Gy) divided into five daily doses of 7 Gy/day. This regimen represents a human equivalent dose of 70 Gy, approximating the same dosage utilized for radiotherapy in oncologic patients. Sham-radiated controls were anesthetized and placed in the radiation apparatus but were not given radiation. All animals were tested for baseline values in both sensorimotor and pain behavioral tests. Sensorimotor testing consisted of the evaluation of walking tracks with the calculation of the Sciatic Functional Index (SFI). Pain-related behavioral measures consisted of mechanical allodynia (von Frey test), cold allodynia (Acetone test), and thermal allodynia (Hargreaves test). Animals were tested serially over an 8-week period. At the study endpoint, electrophysiological and muscle force assessments were completed, and histomorphometric analysis was performed on all sciatic nerves. Animals that underwent radiation treatment displayed significantly greater pain hypersensitivity to mechanical stimulation as compared to sham radiated controls from weeks 4 to 8 of testing. SFI values indicated sensorimotor impairments in the overground gait of radiated animals as compared to non-radiated animals. Furthermore, radiated animals displayed reduced twitch and tetanic muscle force when compared to sham radiated controls. A clinically relevant human equivalent dose of fractionated 35 Gy in rats established significant pain hypersensitivity, impairments in sensorimotor locomotion, and decreased muscle force capacity. This novel rodent model of radiation-induced peripheral neuropathy can be utilized to assess the potential efficacy of therapeutic treatments to either prevent or remediate this clinically debilitating condition.

RXR agonist, 9-cis-13,14-dihydroretinoic acid (9CDHRA), reduces damage and protects from demyelination in transsynaptic degeneration model

Neurodegenerative and demyelinating disease, such as multiple sclerosis (MS) are at the forefront of medical research and the discovery of new drugs and therapeutics. One phenomenon of degeneration seen in these diseases is transsynaptic degeneration (TSD), where damage from one axon spreads to the other axons that are connected to it synaptically. It has previously been found that demyelination occurs prior to neuronal loss in an experimental form of induced TSD. Retinoid-x receptor (RXR) agonists have been shown to promote remyelination. Therefore, this study aimed to reveal the effects of a novel endogenous RXR-γ agonist, 9-cis-13,14-dihydroretinoic acid (9CDHRA), on preventing or restoring the effects of TSD. 9CDHRA was administered to mice following optic nerve crush (ONC) procedures, and electrophysiology (visual evoked potential, VEP) and histological (immunofluorescent) assessments were performed. It was found that 9CDHRA treatment effectively delayed glial activation and reduced the presence of apoptosis at the site of injury and further anterogradely in the visual system, including the lateral geniculate nucleus (LGN) and primary visual cortex (V1). Most notably, 9CDHRA was able to maintain myelin levels following ONC, and effectively protected from demyelination. This was corroborated by VEP recordings with improved P1 latency. The promising findings regarding the injury attenuating and myelin protecting properties of 9CDHRA necessitates further investigations into the potential therapeutic uses of this compound.

Temporal dynamics of neocortical development in organotypic mouse brain cultures: a comprehensive analysis.

Murine organotypic brain slice cultures have been widely used in neuroscientific research and are offering the opportunity to study neuronal function under normal and disease conditions. Despite the broad application, the mechanisms governing the maturation of immature cortical circuits in vitro are not well understood. In this study, we present a detailed investigation into the development of the neocortex in vitro. Using a holistic approach, we studied organotypic whole hemisphere brain slice cultures from postnatal mice and tracked the development of the somatosensory area over a 5-wk period. Our analysis revealed the maturation of passive and active intrinsic properties of pyramidal cells together with their morphology, closely resembling in vivo development. Detailed multielectrode array (MEA) electrophysiological assessments and RNA expression profiling demonstrated stable network properties by 2 wk in culture, followed by the transition of spontaneous activity toward more complex patterns including high-frequency oscillations. However, culturing weeks 4 and 5 exhibited increased variability and initial signs of neuronal loss, highlighting the importance of considering developmental stages in experimental design. This comprehensive characterization is vital for understanding the temporal dynamics of the neocortical development in vitro, with implications for neuroscientific research methodologies, particularly in the investigation of diseases such as epilepsy and other neurodevelopmental disorders.NEW & NOTEWORTHY The development of the mouse neocortex in vitro mimics the in vivo development. Mouse brain cultures can serve as a model system for cortical development for the first 2 wk in vitro and as a model system for the adult cortex from 2 to 4 wk in vitro. Mouse organotypic brain slice cultures develop high-frequency network oscillations at γ frequency after 2 wk in vitro. Mouse brain cultures exhibit increased heterogeneity and variability after 4 wk in culture.

Neuronal repair after spinal cord injury by in vivo astrocyte reprogramming mediated by the overexpression of NeuroD1 and Neurogenin-2

BackgroundAs a common disabling disease, irreversible neuronal death due to spinal cord injury (SCI) is the root cause of functional impairment; however, the capacity for neuronal regeneration in the developing spinal cord tissue is limited. Therefore, there is an urgent need to investigate how defective neurons can be replenished and functionally integrated by neural regeneration; the reprogramming of intrinsic cells into functional neurons may represent an ideal solution.MethodsA mouse model of transection SCI was prepared by forceps clamping, and an adeno-associated virus (AAV) carrying the transcription factors NeuroD1 and Neurogenin-2(Ngn2) was injected in situ into the spinal cord to specifically overexpress these transcription factors in astrocytes close to the injury site. 5-bromo-2´-deoxyuridine (BrdU) was subsequently injected intraperitoneally to continuously track cell regeneration, neuroblasts and immature neurons marker expression, neuronal regeneration, and glial scar regeneration. In addition, immunoprotein blotting was used to measure the levels of transforming growth factor-β (TGF-β) pathway-related protein expression. We also evaluated motor function, sensory function, and the integrity of the blood-spinal cord barrier(BSCB).ResultsThe in situ overexpression of NeuroD1 and Ngn2 in the spinal cord was achieved by specific AAV vectors. This intervention led to a significant increase in cell regeneration and the proportion of cells with neuroblasts and immature neurons cell properties at the injury site(p < 0.0001). Immunofluorescence staining identified astrocytes with neuroblasts and immature neurons cell properties at the site of injury while neuronal marker-specific staining revealed an increased number of mature astrocytes at the injury site. Behavioral assessments showed that the intervention did not improve The BMS (Basso mouse scale) score (p = 0.0726) and gait (p > 0.05), although the treated mice had more sensory sensitivity and greater voluntary motor ability in open field than the non-intervention mice. We observed significant repair of the BSCB at the center of the injury site (p < 0.0001) and a significant improvement in glial scar proliferation. Electrophysiological assessments revealed a significant improvement in spinal nerve conduction (p < 0.0001) while immunostaining revealed that the levels of TGF-β protein at the site of injury in the intervention group were lower than control group (p = 0.0034); in addition, P70 s6 and PP2A related to the TGF-β pathway showed ascending trend (p = 0.0036, p = 0.0152 respectively).ConclusionsThe in situ overexpression of NeuroD1 and Ngn2 in the spinal cord after spinal cord injury can reprogram astrocytes into neurons and significantly enhance cell regeneration at the injury site. The reprogramming of astrocytes can lead to tissue repair, thus improving the reduced threshold and increasing voluntary movements. This strategy can also improve the integrity of the blood-spinal cord barrier and enhance nerve conduction function. However, the simple reprogramming of astrocytes cannot lead to significant improvements in the striding function of the lower limbs.

Benefit of Modulated Masking in hearing according to age

ObjectiveTo analyze the Benefit of Modulated Masking (BMM) on hearing in young, adult and elderly normal-hearing individuals. MethodsThe sample included 60 normal-hearing individuals aged 18–75 years who underwent behavioral assessment (sentence recognition test in the presence of steady and modulated noise) and electrophysiological assessment (cortical Auditory Evoked Potential) to investigate BMM. The results were analyzed comparatively using the paired t-test and ANOVA for repeated measures, followed by the Bonferroni post-hoc test (p-value < 0.05). ResultsA decrease in latencies and an increase in amplitudes of cortical components (P1-N1-P2) was observed due to noise modulation in all age groups. Modulated noise generated better auditory threshold responses (electrophysiological and behavioral), compared to steady noise. The elderly presented a higher threshold in both hearing domains, compared to the other participants, as well as a lower BMM magnitude. ConclusionIt was possible to conclude that the modulated noise generated less interference in the magnitude of the neural response (smaller latencies) and in the neural processing time (larger amplitudes) for the speech stimulus in all participants. The higher auditory thresholds (electrophysiological and behavioral) and the lower BMM magnitude observed in the elderly group, even in the face of noise modulation, suggest a lower temporal auditory performance in this population, and may indicate a deficit in the temporal resolution capacity, associated with the process of aging. Level of evidence3.

Repetitive Transcranial Magnetic Stimulation-Mediated Neuroprotection in the 5xFAD Mouse Model of Alzheimer's Disease Through GABRG2 and SNAP25 Modulation.

Alzheimer's disease (AD) is a leading neurodegenerative disorder with substantial impacts on cognition and behavior. Repetitive transcranial magnetic stimulation (rTMS), a non-invasive neuromodulation technique, has been used to treat various neuropsychiatric disorders, but its efficacy in AD has not been thoroughly investigated. This study examines the neuroprotective effects of rTMS in the 5xFAD mouse model of AD, with a particular focus on its modulation of GABAergic neuronal activity via the GABRG2 and SNAP25 proteins. Transcriptomic sequencing of rTMS-treated 5xFAD mice revealed 32 genes influenced by the treatment, among which GABRG2 was identified as a critical modulatory target. Electrophysiological assessments, including whole-cell patch clamp recordings from frontal cortex neurons, demonstrated significant alterations in inhibitory synaptic currents following rTMS. Subsequent experiments involved sh-GABRG2 transduction combined with rTMS treatment (20Hz, 14 days), examining behavioral responses, GABAergic neuron functionality, cortical GABA expression, cerebrospinal fluid GABA concentrations, β-amyloid accumulation, and pro-inflammatory cytokine levels. The results indicated notable improvements in behavioral performance, enhanced functionality of GABAergic neurons, and reductions in β-amyloid deposition and neuroinflammation after rTMS treatment. Further analysis revealed that SNAP25 overexpression could counteract the negative effects of GABRG2 silencing, highlighting the crucial role of SNAP25 downstream of GABRG2 in mediating rTMS's therapeutic effects in AD. This research highlights rTMS's potential to modulate synaptic and vesicular transport mechanisms, offering a promising avenue for ameliorating symptoms of AD through neuroprotective pathways.

Non-syndromic OTX2-associated pattern dystrophy: a 10-year multimodal imaging study.

To report novel multimodal imaging features and long-term follow-up of Orthodenticle Homeobox 2 (OTX2)-associated pattern Gdystrophy. A 14-year-old boy referred with glaucoma suspect and macular pigmentation underwent fundus autofluorescence imaging, optical coherence tomography, fluorescein and indocyanine green angiography, visual field test, microperimetry and electrophysiology over a ten-year period. Next-generation sequencing panel identified a de novo heterozygous likely pathogenic OTX2 variant, c.259G>A, [p.(Glu87Lys)]. Visual acuity was 20/40 OD and 20/30 OS. Examination showed bilateral enlarged optic nerve heads and increased disc cupping, multiple cilioretinal arteries, a pigmentary maculopathy with stellate-shaped region of hypoautofluorescence, shallow serous macular detachment, subretinal deposits and temporal avascular retina. Angiography showed no source of leakage and absence of retinal neovascularisation despite extensive peripheral non perfusion. Electrophysiological assessments demonstrated mild progressive rod and cone pathway abnormalities, reduced light-adapted b:a ratio, and reduced Arden ratio on electro-oculogram. Ten-year follow-up confirmed a stable disease course despite persistent submacular fluid. There was no associated pituitary structural abnormality or dysfunction. This case study contributes to further understanding of OTX2-associated pattern dystrophy, highlighting its stability over 10 years. Further investigation into inter-individual and intrafamilial variability is warranted.

CPEB2-activated axonal translation of VGLUT2 mRNA promotes glutamatergic transmission and presynaptic plasticity

BackgroundLocal translation at synapses is important for rapidly remodeling the synaptic proteome to sustain long-term plasticity and memory. While the regulatory mechanisms underlying memory-associated local translation have been widely elucidated in the postsynaptic/dendritic region, there is no direct evidence for which RNA-binding protein (RBP) in axons controls target-specific mRNA translation to promote long-term potentiation (LTP) and memory. We previously reported that translation controlled by cytoplasmic polyadenylation element binding protein 2 (CPEB2) is important for postsynaptic plasticity and memory. Here, we investigated whether CPEB2 regulates axonal translation to support presynaptic plasticity.MethodsBehavioral and electrophysiological assessments were conducted in mice with pan neuron/glia- or glutamatergic neuron-specific knockout of CPEB2. Hippocampal Schaffer collateral (SC)-CA1 and temporoammonic (TA)-CA1 pathways were electro-recorded to monitor synaptic transmission and LTP evoked by 4 trains of high-frequency stimulation. RNA immunoprecipitation, coupled with bioinformatics analysis, were used to unveil CPEB2-binding axonal RNA candidates associated with learning, which were further validated by Western blotting and luciferase reporter assays. Adeno-associated viruses expressing Cre recombinase were stereotaxically delivered to the pre- or post-synaptic region of the TA circuit to ablate Cpeb2 for further electrophysiological investigation. Biochemically isolated synaptosomes and axotomized neurons cultured on a microfluidic platform were applied to measure axonal protein synthesis and FM4-64FX-loaded synaptic vesicles.ResultsElectrophysiological analysis of hippocampal CA1 neurons detected abnormal excitability and vesicle release probability in CPEB2-depleted SC and TA afferents, so we cross-compared the CPEB2-immunoprecipitated transcriptome with a learning-induced axonal translatome in the adult cortex to identify axonal targets possibly regulated by CPEB2. We validated that Slc17a6, encoding vesicular glutamate transporter 2 (VGLUT2), is translationally upregulated by CPEB2. Conditional knockout of CPEB2 in VGLUT2-expressing glutamatergic neurons impaired consolidation of hippocampus-dependent memory in mice. Presynaptic-specific ablation of Cpeb2 in VGLUT2-dominated TA afferents was sufficient to attenuate protein synthesis-dependent LTP. Moreover, blocking activity-induced axonal Slc17a6 translation by CPEB2 deficiency or cycloheximide diminished the releasable pool of VGLUT2-containing synaptic vesicles.ConclusionsWe identified 272 CPEB2-binding transcripts with altered axonal translation post-learning and established a causal link between CPEB2-driven axonal synthesis of VGLUT2 and presynaptic translation-dependent LTP. These findings extend our understanding of memory-related translational control mechanisms in the presynaptic compartment.

Distinct neurodevelopmental and epileptic phenotypes associated with gain- and loss-of-function GABRB2 variants

Variants in GABRB2, encoding the β2 subunit of the γ-aminobutyric acid type A (GABAA) receptor, can result in a diverse range of conditions, ranging from febrile seizures to severe developmental and epileptic encephalopathies. However, the mechanisms underlying the risk of developing milder vs more severe forms of disorder remain unclear. In this study, we conducted a comprehensive genotype-phenotype correlation analysis in a cohort of individuals with GABRB2 variants. Genetic and electroclinical data of 42 individuals harbouring 26 different GABRB2 variants were collected and accompanied by electrophysiological analysis of the effects of the variants on receptor function. Electrophysiological assessments of α1β2γ2 receptors revealed that 25/26 variants caused dysfunction to core receptor properties such as GABA sensitivity. Of these, 17 resulted in gain-of-function (GOF) while eight yielded loss-of-function traits (LOF). Genotype-phenotype correlation analysis revealed that individuals harbouring GOF variants suffered from severe developmental delay/intellectual disability (DD/ID, 74%), movement disorders such as dystonia or dyskinesia (59%), microcephaly (50%) and high risk of early mortality (26%). Conversely, LOF variants were associated with milder disease manifestations. Individuals with these variants typically exhibited fever-triggered seizures (92%), milder degrees of DD/ID (85%), and maintained ambulatory function (85%). Notably, severe movement disorders or microcephaly were not reported in individuals with loss-of-function variants. The data reveals that genetic variants in GABRB2 can lead to both gain and loss-of-function, and this divergence is correlated with distinct disease manifestations. Utilising this information, we constructed a diagnostic flowchart that aids in predicting the pathogenicity of recently identified variants by considering clinical phenotypes. This work was funded by the Australian National Health & Medical Research Council, the Novo Nordisk Foundation and The Lundbeck Foundation.

A Prediction Rule for the Dystonic Spread of Blepharospasm: A 4-Year Prospective Cohort Study.

Blepharospasm (BSP), focal dystonia with the highest risk of spread, lacks clear understanding of early spreading risk factors and objective prognostic indicators. We aimed to identify these risk factors through clinical and electrophysiological assessments, and to establish a predictive model for dystonic spread in BSP. We prospectively followed BSP patients for 4 years, collecting data on dystonic spread, and conducting electrophysiological evaluations. The blink reflex, masseter inhibitory reflex, and trigeminal somatosensory evoked potential were assessed. Univariable and multivariable Cox proportional hazard regression models were used to assess clinical characteristics associated with BSP dystonic spread. A predictive model was constructed using a nomogram, and performance of the model was evaluated using the area under the receiver operating characteristic curve. A total of 136 enrolled participants (mean age 56.34 years) completed a 4-year follow-up. Among them, 62 patients (45.6%) showed spread to other body regions. Multivariable Cox regression analysis showed that a high Hamilton Anxiety Scale score (hazard ratio 1.19, 95% confidence interval 1.13-1.25, p < 0.001), prolonged trigeminal somatosensory evoked potential mandibular branch P1-N2 peak interval (hazard ratio 1.11, 95% confidence interval 1.02-1.21, p = 0.017), and elevated trigeminal somatosensory evoked potential mandibular branch P1-N2 peak amplitude (hazard ratio 1.26, 95% confidence interval 1.12-1.41, p < 0.001) were independent risk factors for BSP dystonic spread within 4 years. Combining these factors, the predictive models demonstrated excellent discriminative ability, with the receiver operating characteristic curve score being 0.797, 0.790, 0.847, and 0.820 at 1, 2, 3 and 4 years after enrollment, respectively. We established a predictive model with significant value for anticipating dystonic spread in BSP, offering crucial evidence. These findings contribute essential insights into the early clinical identification of the development and evolution of BSP diseases. ANN NEUROL 2024.

Biallelic variants in COX18 cause a mitochondrial disorder primarily manifesting as peripheral neuropathy.

Defects in mitochondrial dynamics are a common cause of Charcot-Marie-Tooth disease (CMT), while primary deficiencies in the mitochondrial respiratory chain (MRC) are rare and atypical for this etiology. This study aims to report COX18 as a novel CMT-causing gene. This gene encodes an assembly factor of mitochondrial Complex IV (CIV) that translocates the C-terminal tail of MTCO2 across the mitochondrial inner membrane. Exome sequencing was performed in four affected individuals. The patients and available family members underwent thorough neurological and electrophysiological assessment. The impact of one of the identified variants on splicing, protein levels, and mitochondrial bioenergetics was investigated in patient-derived lymphoblasts. The functionality of the mutant protein was assessed using a Proteinase K protection assay and immunoblotting. Neuronal relevance of COX18 was assessed in a Drosophila melanogaster knockdown model. Exome sequencing coupled with homozygosity mapping revealed a homozygous splice variant c.435-6A>G in COX18 in two siblings with early-onset progressive axonal sensory-motor peripheral neuropathy. By querying external databases, we identified two additional families with rare deleterious biallelic variants in COX18 . All affected individuals presented with axonal CMT and some patients also exhibited central nervous system symptoms, such as dystonia and spasticity. Functional characterization of the c.435-6A>G variant demonstrated that it leads to the expression of an alternative transcript that lacks exon 2, resulting in a stable but defective COX18 isoform. The mutant protein impairs CIV assembly and activity, leading to a reduction in mitochondrial membrane potential. Downregulation of the COX18 homolog in Drosophila melanogaster displayed signs of neurodegeneration, including locomotor deficit and progressive axonal degeneration of sensory neurons. Our study presents genetic and functional evidence that supports COX18 as a newly identified gene candidate for autosomal recessive axonal CMT with or without central nervous system involvement. These findings emphasize the significance of peripheral neuropathy within the spectrum of primary mitochondrial disorders and the role of mitochondrial CIV in the development of CMT. Our research has important implications for the diagnostic workup of CMT patients.

USP38 exacerbates pressure overload-induced left ventricular electrical remodeling

BackgroundUbiquitin-specific protease 38 (USP38), belonging to the USP family, is recognized for its role in controlling protein degradation and diverse biological processes. Ventricular arrhythmias (VAs) following heart failure (HF) are closely linked to ventricular electrical remodeling, yet the specific mechanisms underlying VAs in HF remain inadequately explored. In this study, we examined the impact of USP38 on VAs in pressure overload-induced HF.MethodsCardiac-specific USP38 knockout mice, cardiac-specific USP38 transgenic mice and their matched control littermates developed HF induced by aortic banding (AB) surgery. After subjecting the mice to AB surgery for a duration of four weeks, comprehensive investigations were conducted, including pathological analysis and electrophysiological assessments, along with molecular analyses.ResultsWe observed increased USP38 expression in the left ventricle of mice with HF. Electrocardiogram showed that the USP38 knockout shortened the QRS interval and QTc, while USP38 overexpression prolonged these parameters. USP38 knockout decreased the susceptibility of VAs by shortening action potential duration (APD) and prolonging effective refractory period (ERP). In addition, USP38 knockout increased ion channel and Cx43 expression in ventricle. On the contrary, the increased susceptibility of VAs and the decreased expression of ventricular ion channels and Cx43 were observed with USP38 overexpression. In both in vivo and in vitro experiments, USP38 knockout inhibited TBK1/AKT/CAMKII signaling, whereas USP38 overexpression activated this pathway.ConclusionOur data indicates that USP38 increases susceptibility to VAs after HF through TBK1/AKT/CAMKII signaling pathway, Consequently, USP38 may emerge as a promising therapeutic target for managing VAs following HF.

Development of a major histocompatibility complex class II conditional knockout mouse to study cell-specific and time-dependent adaptive immune responses in peripheral nerves.

The precise relationship between molecular mimicry and tissue-specific autoimmunity is unknown. Major histocompatibility complex (MHC) class II antigen presenting cell-CD4+ T-cell receptor complex interactions are necessary for adaptive immunity. This study aimed to determine the role of endoneurial endothelial cell MHC class II in autoimmune polyneuropathy. Cryopreserved Guillain-Barré syndrome (GBS) patient sural nerve biopsies and sciatic nerves from the severe murine experimental autoimmune neuritis (sm-EAN) GBS model were studied. Cultured conditional ready MHC Class II antigen A-alpha chain (H2-Aa) embryonic stem cells were used to generate H2-Aaflox/+ C57BL/6 mice. Mice were backcrossed and intercrossed to the SJL background to generate H2-Aaflox/flox SJL mice, bred with hemizygous Tamoxifen-inducible von Willebrand factor Cre recombinase (vWF-iCre/+) SJL mice to generate H2-Aaflox/flox; vWF-iCre/+ mice to study microvascular endothelial cell adaptive immune responses. Sm-EAN was induced in Tamoxifen-treated H2-Aaflox/flox; vWF-iCre/+, H2-Aaflox/flox; +/+, H2-Aa+/+; vWF-iCre/+ and untreated H2-Aaflox/flox; vWF-iCre/+ adult female SJL mice. Neurobehavioral, electrophysiological and histopathological assessments were performed at predefined time points. Endoneurial endothelial cell MHC class II expression was observed in normal and inflamed human and mouse peripheral nerves. Tamoxifen-treated H2-Aaflox/flox; vWF-iCre/+ mice were resistant to sm-EAN despite extensive MHC class II expression in lymphoid and non-lymphoid tissues. A conditional MHC class II knockout mouse to study cell- and time-dependent adaptive immune responses in vivo was developed. Initial studies show microvascular endothelial cell MHC class II expression is necessary for peripheral nerve specific autoimmunity, as advocated by human in vitro adaptive immunity and ex vivo transplant rejection studies.

Identification of Matrine as a Kirsten rats Arcomaviral oncogene homolog inhibitor alleviating chemotherapy-induced neuropathic pain

BackgroundChemotherapy-induced peripheral neuropathy (CIPN) represents a prevailing and severe clinical concern, characterized by limited availability of clinically effective treatment strategies. Current evidence endorses matrine's potential as a neuroprotective and analgesic agent for CIPN. Nevertheless, the precise targets and mechanisms of action of matrine remain insufficiently explored, impeding comprehensive pharmacological investigation and clinical application. ObjectiveThis study endeavors to elucidate the analgesic and neuroprotective effects of matrine in mice with vincristine-induced neuropathic pain. A focal point is the identification of matrine's specific target and the underlying molecular mechanisms governing its analgesic and neuroprotective actions. MethodsTo discern matrine's analgesic effects in CIPN mice, we conducted behavioral experiments encompassing the Von Frey filament test and Hargreaves Test. Furthermore, we conducted electrophysiological and histopathological assessments involving HE staining, Nissl staining, and Fluoro-Jade B staining to evaluate matrine's effects on neuroprotection within dorsal root ganglia and the spinal cord of CIPN mice. Sequentially, thermal shift assay, GTP hydrolysis assay, and nucleotide exchange assay were executed to validate matrine's inhibitory effects on KRAS. Molecular docking and site-directed mutagenesis experiments were implemented to identify the precise binding pocket of matrine on KRAS. Lastly, matrine's inhibitory effects on downstream signaling pathways of KRAS were confirmed through experiments conducted at animal model. ResultsMatrine exhibited a notable increase in mechanical withdrawal threshold and thermal withdrawal latency in vincristine-treated mice. This compound substantially ameliorated the neurofunctional blockade associated with sensory and motor functions induced by vincristine. Moreover, matrine mitigated pathological damage within DRG and the L4-L5 spinal cord regions. The study's MST experiments indicated matrine's substantial elevation of KRAS's melting temperature. The GTP hydrolysis and nucleotide exchange assays revealed concentration-dependent inhibition of KRAS activity by matrine. Molecular docking provided insight into the binding mode of matrine with KRAS, while site-directed mutagenesis verified the specific binding site of matrine on KRAS. Lastly, matrine's inhibition of downstream Raf/Erk1/2 and PI3K/Akt/mTOR signaling pathways of KRAS was confirmed in VCR mice. ConclusionCompared to previous studies, our research has identified matrine as a natural inhibitor of the elusive protein KRAS, often considered "undruggable." Furthermore, this study has revealed that matrine exerts its therapeutic effects on chemotherapy-induced peripheral neuropathy (CIPN) by inhibiting KRAS activation, subsequently suppressing downstream signaling pathways such as Raf/Erk1/2 and PI3K/Akt/mTOR. This investigation signifies the discovery of a novel target for matrine, thus expanding the potential scope of its involvement in KRAS-related biological functions and diseases. These findings hold the promise of providing a crucial experimental foundation for forthcoming drug development initiatives centered around matrine, thereby advancing the field of pharmaceutical research.

Exploring laser-induced acute and chronic retinal vein occlusion mouse models: Development, temporal in vivo imaging, and application perspectives.

Photodynamic venous occlusion is a commonly accepted method for establishing mouse models of retinal vein occlusion (RVO). However, existing model parameters do not distinguish between acute and chronic RVO subtypes. Large variations in laser energy seem to correlate with fluctuating retinopathy severity and high rates of venous recanalization during the acute phase, along with the variable levels of retinal perfusion during the chronic phase. After optimizing the modeling procedure and defining success and exclusion criteria, laser energy groups of 80mW, 100mW, and 120mW were established. Multimodal imaging confirmed that higher energy levels increased the incidence of retinal cystoid edema and intraretinal hemorrhage, exacerbated the severity of exudative retinal detachment, and reduced the venous recanalization rate. For the acute model, 100mW was considered an appropriate parameter for balancing moderate retinopathy and venous recanalization. Continuous imaging follow-up revealed that day 1 after RVO was the optimal observation point for peaking of retinal thickness and intensive occurrence of retinal cystic edema and intraretinal hemorrhage. After excluding the influence of venous recanalization on retinal thickness, acute retinal edema demonstrated a positive response to standard anti-vascular endothelial growth factor therapy, validating the clinical relevance of the acute RVO model for further study in pathogenic mechanisms and therapeutic efficacy. For the chronic model, the 120mW parameter with the lowest venous recanalization rate was applied, accompanied by an increase in both photocoagulation shots and range to ensure sustained vein occlusion. Imaging follow-up clarified non-ischemic retinopathy characterized by tortuosity and dilation of the distal end, branches, and adjacent veins of the occluded vein. These morphological changes are quantifiable and could be combined with electrophysiological functional assessment for treatment effectiveness evaluation. Moreover, the stable state of venous occlusion may facilitate investigations into response and compensation mechanisms under conditions of chronic retinal hypoperfusion.

Clinical and Molecular Characterization of AIPL1-Associated Leber Congenital Amaurosis/Early-Onset Severe Retinal Dystrophy

PurposeThis study aimed to characterize the clinical features, genetic findings, and genotype-phenotype correlations of patients with Leber congenital amaurosis (LCA) or early-onset severe retinal dystrophy (EOSRD) harboring biallelic AIPL1 pathogenic variants. DesignRetrospective case series. MethodsThis study consecutively enrolled 51 patients from 47 families with a clinical diagnosis of LCA/EOSRD harboring disease-causing variants in the AIPL1 gene, from October 2021 to September 2023. Molecular genetic findings, medical history, and ophthalmic evaluation including visual acuity (VA), multimodal retinal imaging, and electrophysiologic assessment were reviewed. ResultsOf the 51 patients (32 with LCA and 19 with EOSRD), 27 (53%) were females, and age at last review ranged from 0.5 to 58.4 years. We identified 28 disease-causing AIPL1 variants, with 18 being novel. In patients with EOSRD, the mean (range) VA was 1.3 (0.7-2.7) logMAR and 1.3 (0.5-2.3) logMAR for right and left eyes respectively, with an average annual decline of 0.03 logMAR (R2 = 0.7547, P < .01). For patients with LCA, the VA ranged from light perception to counting fingers. Optical coherence tomography imaging demonstrated preservation of foveal ellipsoid zone in the 5 youngest EOSRD patients and 9 LCA children. Electroretinography showed severe cone-rod patterns in 78.6% (11/14) of patients with EOSRD, while classical extinguished pattern was documented in all patients with LCA available for the examination. The most common mutation was the nonsense variants of c.421C>T, with an allele frequency of 53.9%. All patients with EOSRD carried at least one missense mutation, of whom 13 identified with c.152A>G and 5 with c.572T>C. Twenty-six patients with LCA harbored two null AIPL1 variants, while 18 were homozygous for c.421C>T and 6 were heterozygous for c.421C>T with another loss-of-function variant. ConclusionsThis study reveals distinct clinical features and variation spectrum between AIPL1-associated LCA and EOSRD. Patients harboring at least one nonnull mutation, especially c.152A>G and c.572T>C, were significantly more likely to have a milder EOSRD phenotype than those with two null mutations. Residual foveal outer retinal structure observed in the youngest proportion of patients suggests an early window for gene augmentation therapy.