Adaptive autophagy reprogramming in Schwann cells during peripheral demyelination.

The myelin sheath is an essential structure for the rapid transmission of electrical impulses through axons, and peripheral myelination is a well-programmed postnatal process of Schwann cells (SCs), the myelin-forming peripheral glia. SCs transdifferentiate into demyelinating SCs (DSCs) to remove the myelin sheath during Wallerian degeneration after axonal injury and demyelinating neuropathies, and macrophages are responsible for the degradation of myelin under both conditions. In this study, the mechanism by which DSCs acquire the ability of myelin exocytosis was investigated. Using serial ultrastructural evaluation, we found that autophagy-related gene 7-dependent formation of a "secretory phagophore (SP)" and tubular phagophore was necessary for exocytosis of large myelin chambers by DSCs. DSCs seemed to utilize myelin membranes for SP formation and employed p62/sequestosome-1 (p62) as an autophagy receptor for myelin excretion. In addition, the acquisition of the myelin exocytosis ability of DSCs was associated with the decrease in canonical autolysosomal flux and was demonstrated by p62 secretion. Finally, this SC demyelination mechanism appeared to also function in inflammatory demyelinating neuropathies. Our findings show a novel autophagy-mediated myelin clearance mechanism by DSCs in response to nerve damage.

Clinical characteristics of benign paroxysmal positional vertigo after traumatic brain injury.

INTRODUCTION: The aim of the present study was to evaluate the characteristics of brain injury and to assess the relationship between them and treatment outcomes in patients with traumatic benign paroxysmal positional vertigo (t-BPPV). MATERIALS AND METHODS: Sixty-three consecutive patients who were diagnosed with BPPV within 2 weeks after head trauma were included. RESULTS: Cerebral concussion, intracranial hemorrhages (ICH), skull fracture without ICH, and hemorrhagic contusion were observed in 68%, 24%, 5%, and 3% of t-BPPV patients, respectively. BPPV with single canal involvement was observed in 52 (83%) patients and that with multiple canal involvement was observed in 11 (17%) patients. The number of treatment sessions was not significantly different according to the cause of head trauma (p = 0.252), type of brain injury (p = 0.308) or location of head trauma (p = 0.287). The number of recurrences was not significantly different according to the cause of head trauma (p = 0.308), type of brain injury (p = 0.536) or location of head trauma (p = 0.138). CONCLUSION: The present study demonstrated that there were no significant differences in treatment sessions until resolution and the mean number of recurrences according to the type of brain injury.

FK506-binding protein-like and FK506-binding protein 8 regulate dual leucine zipper kinase degradation and neuronal responses to axon injury.

The dual leucine zipper kinase (DLK) is a key regulator of axon regeneration and degeneration in response to neuronal injury; however, regulatory mechanisms of the DLK function via its interacting proteins are largely unknown. To better understand the molecular mechanism of DLK function, we performed yeast two-hybrid screening analysis and identified FK506-binding protein-like (FKBPL, also known as WAF-1/CIP1 stabilizing protein 39) as a DLK-binding protein. FKBPL binds to the kinase domain of DLK and inhibits its kinase activity. In addition, FKBPL induces DLK protein degradation through ubiquitin-dependent pathways. We further assessed other members in the FKBP protein family and found that FK506-binding protein 8 (FKBP8) also induced DLK degradation. We identified the lysine 271 residue in the kinase domain as a major site of DLK ubiquitination and SUMO3 conjugation and was thus responsible for regulating FKBP8-mediated proteasomal degradation that was inhibited by the substitution of the lysine 271 to arginine. FKBP8-mediated degradation of DLK is mediated by autophagy pathway because knockdown of Atg5 inhibited DLK destabilization. We show that in vivo overexpression of FKBP8 delayed the progression of axon degeneration and suppressed neuronal death after axotomy in sciatic and optic nerves. Taken together, this study identified FKBPL and FKBP8 as novel DLK-interacting proteins that regulate DLK stability via the ubiquitin-proteasome and lysosomal protein degradation pathways.

Regulation of the V-ATPase subunit ATP6V0D2 and its role in demyelination after peripheral nerve injury.

After peripheral nerve injury, demyelinating Schwann cells discharge myelin debris and macrophages execute myelin degradation, leading to demyelination of degenerating axons, which is essential for efficient nerve regeneration. In this study, we show that vacuolar-type proton ATPase subunit d2 (Atp6v0d2) is among the most highly upregulated genes in degenerating mouse sciatic nerves after nerve injury using microarray analysis. ATP6V0D2 is mostly expressed in macrophages of injured nerves. Atp6v0d2 knockout mice display delayed peripheral nerve demyelination and significantly attenuated myelin lipid digestion after nerve injury. However, macrophage recruitment and Schwann cell dedifferentiation are unaffected by loss of Atp6v0d2 expression. Taken together, these data demonstrate that ATP6V0D2 in macrophages is specifically required for demyelination during Wallerian degeneration.

Rapid generation of potent antibodies by autonomous hypermutation in yeast.

The predominant approach for antibody generation remains animal immunization, which can yield exceptionally selective and potent antibody clones owing to the powerful evolutionary process of somatic hypermutation. However, animal immunization is inherently slow, not always accessible and poorly compatible with many antigens. Here, we describe 'autonomous hypermutation yeast surface display' (AHEAD), a synthetic recombinant antibody generation technology that imitates somatic hypermutation inside engineered yeast. By encoding antibody fragments on an error-prone orthogonal DNA replication system, surface-displayed antibody repertoires continuously mutate through simple cycles of yeast culturing and enrichment for antigen binding to produce high-affinity clones in as little as two weeks. We applied AHEAD to generate potent nanobodies against the SARS-CoV-2 S glycoprotein, a G-protein-coupled receptor and other targets, offering a template for streamlined antibody generation at large.

The stem cell marker Prom1 promotes axon regeneration by down-regulating cholesterol synthesis via Smad signaling.

Axon regeneration is regulated by a neuron-intrinsic transcriptional program that is suppressed during development but that can be reactivated following peripheral nerve injury. Here we identify Prom1, which encodes the stem cell marker prominin-1, as a regulator of the axon regeneration program. Prom1 expression is developmentally down-regulated, and the genetic deletion of Prom1 in mice inhibits axon regeneration in dorsal root ganglion (DRG) cultures and in the sciatic nerve, revealing the neuronal role of Prom1 in injury-induced regeneration. Elevating prominin-1 levels in cultured DRG neurons or in mice via adeno-associated virus-mediated gene delivery enhances axon regeneration in vitro and in vivo, allowing outgrowth on an inhibitory substrate. Prom1 overexpression induces the consistent down-regulation of cholesterol metabolism-associated genes and a reduction in cellular cholesterol levels in a Smad pathway-dependent manner, which promotes axonal regrowth. We find that prominin-1 interacts with the type I TGF-ß receptor ALK4, and that they synergistically induce phosphorylation of Smad2. These results suggest that Prom1 and cholesterol metabolism pathways are possible therapeutic targets for the promotion of neural recovery after injury.

Direction-changing spontaneous nystagmus in patients with dizziness.

PURPOSE: The present study aimed to investigate the clinical features of patients with direction-changing spontaneous nystagmus (DCSN) and gain insight into its underlying mechanisms. METHODS: Medical records and vestibular function test results collected in our dizziness clinic between February 2013 and February 2020 were retrospectively reviewed. Spontaneous nystagmus was recorded while sitting upright using videonystagmography for 2 min to confirm the spontaneous changes in nystagmus direction. Causative disease diagnoses were based on the patients' clinical history, audiometry results, vestibular function tests, and imaging studies. RESULTS: Of 4786 patients, DCSN was observed in 41 (0.86%). Causative disease diagnoses included vestibular neuritis (n = 9), lateral semicircular canal cupulopathy (n = 9), cerebellopontine angle tumor (n = 8), vestibular paroxysmia (n = 2), vestibular migraine (n = 2), vestibular nucleus infarction (n = 1), sudden sensorineural hearing loss with vertigo (n = 2), Meniere's disease (n = 2), Ramsay Hunt syndrome (n = 1), labyrinthine fistula due to middle ear cholesteatoma (n = 1), lateral semicircular canal dysplasia (n = 1), post tympanomastoidectomy dizziness (n = 1), and head trauma (n = 2). CONCLUSIONS: Although the periodicity of DCSN could not be determined because of insufficiently long observation times, it was observed in various central and peripheral vestibulopathies. Careful examination of spontaneous nystagmus over a sufficient period may ensure the detection of DCSN when evaluating dizziness.

ßPix Guanine Nucleotide Exchange Factor Regulates Regeneration of Injured Peripheral Axons.

Axon regeneration is essential for successful recovery after peripheral nerve injury. Although growth cone reformation and axonal extension are crucial steps in axonal regeneration, the regulatory mechanisms underlying these dynamic processes are poorly understood. Here, we identify ßPix (Arhgef7), the guanine nucleotide exchange factor for Rac1 GTPase, as a regulator of axonal regeneration. After sciatic nerve injury in mice, the expression levels of ßPix increase significantly in nerve segments containing regenerating axons. In regrowing axons, ßPix is localized in the peripheral domain of the growth cone. Using ßPix neuronal isoform knockout (NIKO) mice in which the neuronal isoforms of ßPix are specifically removed, we demonstrate that ßPix promotes neurite outgrowth in cultured dorsal root ganglion neurons and in vivo axon regeneration after sciatic nerve crush injury. Activation of cJun and STAT3 in the cell bodies is not affected in ßPix NIKO mice, supporting the local action of ßPix in regenerating axons. Finally, inhibiting Src, a kinase previously identified as an activator of the ßPix neuronal isoform, causes axon outgrowth defects in vitro, like those found in the ßPix NIKO neurons. Altogether, these data indicate that ßPix plays an important role in axonal regrowth during peripheral nerve regeneration.

Src-mediated phosphorylation of ßPix-b regulates dendritic spine morphogenesis.

PAK-interacting guanine nucleotide exchange factor (ßPix; also known as Arhgef7) has been implicated in many actin-based cellular processes, including spine morphogenesis in neurons. However, the molecular mechanisms by which ßPix controls spine morphology remain elusive. Previously, we have reported the expression of several alternative spliced ßPix isoforms in the brain. Here, we report a novel finding that the b isoform of ßPix (ßPix-b) mediates the regulation of spine and synapse formation. We found that ßPix-b, which is mainly expressed in neurons, enhances spine and synapse formation through preferential localization at spines. In neurons, glutamate treatment efficiently stimulates Rac1 GEF activity of ßPix-b. The glutamate stimulation also promotes Src-mediated phosphorylation of ßPix-b in both an AMPA receptor- and NMDA receptor-dependent manner. Tyrosine 598 (Y598) of ßPix-b is identified as the major Src-mediated phosphorylation site. Finally, Y598 phosphorylation of ßPix-b enhances its Rac1 GEF activity that is critical for spine and synapse formation. In conclusion, we provide a novel mechanism by which ßPix-b regulates activity-dependent spinogenesis and synaptogenesis via Src-mediated phosphorylation.

Nystagmus in Ramsay Hunt syndrome with or without dizziness.

BACKGROUND: The presence of dizziness has been reported as a negative prognostic factor for recovery of facial palsy in Ramsay Hunt syndrome (RHS). The aim of this study was to investigate the incidence and patterns of nystagmus in RHS patients without dizziness, and discuss possible mechanisms. We also compared the severity and prognosis of facial palsy between RHS patients with and without dizziness. METHODS: From January 2014 to January 2019, 36 patients diagnosed with RHS (27 with dizziness and 9 without dizziness) were included. Patterns of nystagmus were examined and categorized using video-nystagmography. House-Brackmann(HB) grade of facial palsy was compared between RHS patients with and without dizziness. RESULTS: Not only RHS patients with dizziness exhibited nystagmus in most cases (96%, 26 of 27) but also as many as 67% (6 of 9) of RHS patients without dizziness exhibited nystagmus, though the intensity was remarkably weak. In both groups of RHS with and without dizziness, direction-fixed nystagmus and direction-changing positional nystagmus were observed. Initial HB grade and recovery of facial palsy after treatment were not significantly different between RHS with and without dizziness. CONCLUSION: Various patterns of nystagmus including direction-fixed and positional direction-changing nystagmus were observed in RHS patients, and inflammation of the vestibular nerve and inner ear end organs may be responsible for the production of nystagmus in these patients. The results support that the evaluation of vestibular function may be necessary even in RHS patients who do not complain of dizziness or vertigo.

Facial Nerve Hematoma After Penetrating Middle Ear Trauma: A Cause of Delayed Facial Palsy.

ABSTRACT: Penetrating middle ear injury may cause hearing loss, vertigo, or facial nerve injury, although facial nerve paralysis followed by head trauma is a rare condition. In this study, we report a case of a 3-year-old patient with delayed facial palsy on the left side that developed 4 days after an accidental tympanic membrane perforation caused by a cotton-tipped swab. Otoendoscopic examination revealed a perforation in the posterosuperior quadrant of the tympanic membrane. Audiometry revealed no hearing loss on the injured side, and eye movement examination did not reveal spontaneous or positional nystagmus. Pre- and postcontrast T1-weighted magnetic resonance imaging demonstrated high signal intensity along the tympanic portion of the fallopian canal, which suggested that hemorrhage within the facial canal may be a cause of delayed facial palsy. It can be assumed that traumatic injury at the dehiscent facial nerve in the tympanic portion caused hematoma within the fallopian canal, resulting in delayed facial nerve palsy.

DLK regulates a distinctive transcriptional regeneration program after peripheral nerve injury.

Following damage to a peripheral nerve, injury signaling pathways converge in the cell body to generate transcriptional changes that support axon regeneration. Here, we demonstrate that dual leucine zipper kinase (DLK), a central regulator of injury responses including axon regeneration and neuronal apoptosis, is required for the induction of the pro-regenerative transcriptional program in response to peripheral nerve injury. Using a sensory neuron-conditional DLK knockout mouse model, we show a time course for the dependency of gene expression changes on the DLK pathway after sciatic nerve injury. Gene ontology analysis reveals that DLK-dependent gene sets are enriched for specific functional annotations such as ion transport and immune response. A series of comparative analyses shows that the DLK-dependent transcriptional program is distinct from that promoted by the importin-dependent retrograde signaling pathway, while it is partially shared between PNS and CNS injury responses. We suggest that DLK-dependency might provide a selective filter for regeneration-associated genes among the injury-responsive transcriptome.

Atypical clinical manifestations of herpes zoster oticus: diagnostic usefulness of magnetic resonance imaging.

Typical symptoms of Ramsay Hunt syndrome (RHS) consist of painful vesicular eruptions in the external ear, unilateral facial palsy, and/or vestibulocochlear deficit. When RHS patients show atypical clinical manifestations, correct diagnosis can be delayed, and ideal treatment timing for antiviral therapy may be missed. The aim of this study is to describe RHS patients with atypical clinical manifestations and evaluate the usefulness of magnetic resonance imaging (MRI) for early differential diagnosis. We retrospectively reviewed the clinical data and investigated the findings of internal auditory canal (IAC) MRI of seven patients diagnosed with RHS presenting "atypical" clinical manifestations between January 2013 and December 2016. "Typical" symptoms of RHS consist of herpetic vesicular eruption and facial palsy with or without vestibulocochlear deficit. Regardless of symptomatic presentations, IAC MRI demonstrated post-contrast enhancement of cranial nerve (CN) VII, CN VIII, and IAC dura in patients with atypical clinical manifestations. In cases with multiple lower CN palsy, enhancement along the involved nerve was observed on IAC MRI. When RHS was complicated by acute parotiditis, diffuse enhancement of the parotid gland was demonstrated. The present study shows that in IAC MRI of RHS patients with atypical clinical manifestations, post-contrast enhancement was not confined to the facial nerve but also observed in CN VIII and IAC dura regardless of the symptoms, which may facilitate early diagnosis of RHS.

Cortical and subcortical changes in resting-state functional connectivity before and during an episode of postoperative delirium.

OBJECTIVE: Delirium is an acute brain failure related to uncertain problems in neural connectivity, including aberrant functional interactions between remote cortical regions. This study aimed to elucidate the underlying neural mechanisms of delirium by clarifying the changes in resting-state functional connectivity induced by postoperative delirium using imaging data scanned before and after surgery. METHOD: Fifty-eight patients with a femoral neck fracture were preoperatively scanned using resting-state functional magnetic resonance imaging. Twenty-five patients developed postoperative delirium, and 14 of those had follow-up scans during delirium. Eighteen patients without delirium completed follow-up scans 5 or 6 days after surgery. We assessed group differences in voxel-based connectivity, in which the seeds were the posterior cingulate cortex, medial prefrontal cortex and 11 subcortical regions. Connections between the subcortical regions were also examined. RESULTS: The results showed four major findings during delirium. Both the posterior cingulate cortex and medial prefrontal cortex were strongly connected to the dorsolateral prefrontal cortex. The posterior cingulate cortex had hyperconnectivity with the inferior parietal lobule, whereas the medial prefrontal cortex had hyperconnectivity with the frontopolar cortex and hypoconnectivity with the superior frontal gyrus. Connectivity of the striatum with the anterior cingulate cortex and insula was increased. Disconnections were found between the lower subcortical regions including the neurotransmitter origins and the striatum/thalamus in the upper level. CONCLUSIONS: Our findings suggest that cortical dysfunction during delirium is characterized by a diminution of the anticorrelation between the default mode network and task-positive regions, excessive internal connections in the posterior default mode network and a complex imbalance of internal connectivity in the anterior default mode network. These dysfunctions can be attributed to the loss of reciprocity between the default mode network and central executive network associated with defective function in the salience network, which might be closely linked to aberrant subcortical neurotransmission-related connectivity and striato-cortical connectivity.

Horizontal transfer of DNA methylation patterns into bacterial chromosomes.

Horizontal gene transfer (HGT) is the non-inherited acquisition of novel DNA sequences. HGT is common and important in bacteria because it enables the rapid generation of new phenotypes such as antibiotic resistance. Here we show that in vivo and in vitro DNA methylation patterns can be horizontally transferred into bacterial chromosomes to program cell phenotypes. The experiments were performed using a synthetic system in Escherichia coli where different DNA methylation patterns within the cis-regulatory sequence of the agn43 gene turn on or off a fluorescent reporter (CFP). With this system we demonstrated that DNA methylation patterns not only accompany the horizontal transfer of genes into the bacterial cytoplasm but can be transferred into chromosomes by: (i) bacteriophage P1 transduction; and (ii) transformation of extracellular synthetic DNA. We also modified the experimental system by replacing CFP with the SgrS small RNA, which regulates glucose and methyl α-D-glucoside uptake, and showed that horizontally acquired DNA methylation patterns can increase or decrease cell fitness. That is, horizontally acquired DNA methylation patterns can result in the selection for and against cells that have HGT. Findings from these proof-of-concept experiments have applications in synthetic biology and potentially broad implications for bacterial adaptation and evolution.

Aversive eye gaze during a speech in virtual environment in patients with social anxiety disorder.

OBJECTIVE: One of the main characteristics of social anxiety disorder is excessive fear of social evaluation. In such situations, anxiety can influence gaze behaviour. Thus, the current study adopted virtual reality to examine eye gaze pattern of social anxiety disorder patients while presenting different types of speeches. METHODS: A total of 79 social anxiety disorder patients and 51 healthy controls presented prepared speeches on general topics and impromptu speeches on self-related topics to a virtual audience while their eye gaze was recorded. Their presentation performance was also evaluated. RESULTS: Overall, social anxiety disorder patients showed less eye gaze towards the audience than healthy controls. Types of speech did not influence social anxiety disorder patients' gaze allocation towards the audience. However, patients with social anxiety disorder showed significant correlations between the amount of eye gaze towards the audience while presenting self-related speeches and social anxiety cognitions. CONCLUSION: The current study confirms that eye gaze behaviour of social anxiety disorder patients is aversive and that their anxiety symptoms are more dependent on the nature of topic.

Paradoxical suppression of small RNA activity at high Hfq concentrations due to random-order binding.

Small RNAs (sRNAs) are important regulators of gene expression during bacterial stress and pathogenesis. sRNAs act by forming duplexes with mRNAs to alter their translation and degradation. In some bacteria, duplex formation is mediated by the Hfq protein, which can bind the sRNA and mRNA in each pair in a random order. Here we investigate the consequences of this random-order binding and experimentally demonstrate that it can counterintuitively cause high Hfq concentrations to suppress rather than promote sRNA activity in Escherichia coli. As a result, maximum sRNA activity occurs when the Hfq concentration is neither too low nor too high relative to the sRNA and mRNA concentrations ('Hfq set-point'). We further show with models and experiments that random-order binding combined with the formation of a dead-end mRNA-Hfq complex causes high concentrations of an mRNA to inhibit its own duplex formation by sequestering Hfq. In such cases, maximum sRNA activity requires an optimal mRNA concentration ('mRNA set-point') as well as an optimal Hfq concentration. The Hfq and mRNA set-points generate novel regulatory properties that can be harnessed by native and synthetic gene circuits to provide greater control over sRNA activity, generate non-monotonic responses and enhance the robustness of expression.

A personality trait contributes to the occurrence of postoperative delirium: a prospective study.

BACKGROUND: Although various physical risk factors for delirium have been identified, the effect of psychological aspects is currently unknown. This study aimed to examine psychological risk factors for postoperative delirium and to identify hidden subgroups of delirium in clinical and psychological feature space. METHODS: Among 200 patients with hip fracture, 78 elderly patients were prospectively evaluated for clinical and psychological assessments before surgery. As delirium was assessed from the next day to the 7th day after surgery, postoperative delirium was found in 40 patients, but not in 38 patients. Univariate and multivariate logistic regression analyses were used to explore risk factors for postoperative delirium. Phenotypic subgroups of delirium were assessed using Topological Data Analysis, in which the significant risk factors were used for evaluating filter and distance metrics. RESULTS: Mini-Mental State Examination, neuroticism, conscientiousness, and regional anesthesia were identified as a predictive risk factor for postoperative delirium. The filter metric showed significant negative correlations with nutrition-related factors such as total protein and albumin. When filter metric and Euclidean distances were entered, delirious patients were bifurcated as a function of personality traits and anesthesia method in the patient-patient network. CONCLUSIONS: A personality trait of neuroticism and conscientiousness may predispose elderly patients to postoperative delirium and this influence may be amplified by regional anesthesia. This study verifies the contribution of psychological risk factors to delirium and provides new insight for complex etiologies of delirium by mapping various clinical variables in the topological space.

Clinical manifestations in patients with herpes zoster oticus.

Patients with herpes zoster oticus (HZO) may exhibit diverse symptoms regarding cochleovestibular dysfunction. This study investigated the clinical manifestations of HZO by comparing symptoms associated with dysfunctions of the 7th and 8th cranial nerves (CN VII and VIII, respectively). This study is a retrospective case series. Eighty-one patients with HZO who had dysfunction of CN VII or VIII were included in this study. Electroneuronography (ENoG) values were compared among patient groups with facial weakness. Patients with ipsilateral facial weakness (62 of 81) were more common than those without. Among 81 patients, those with facial weakness, hearing loss, and vertigo were most common, and only 1 patient had vertigo without hearing loss or facial weakness. Most patients with vertigo also had hearing loss (28 of 30), and patients without hearing loss did not have vertigo (19 of 21). While patients with vertigo had worse ENoG values than those without vertigo, ENoG values were not significantly different between patients with and without hearing loss. In conclusion, various clinical manifestations of CN VII and VIII dysfunction are possible in patients with HZO. Patients with vertigo had worse ENoG values than those without, which may indicate that vertigo reflects more severe facial nerve degeneration in HZO patients with facial weakness.