Regulation of lipid synthesis in myelin modulates neural activity and is required for motor learning.

Brain function relies on both rapid electrical communication in neural circuitry and appropriate patterns or synchrony of neural activity. Rapid communication between neurons is facilitated by wrapping nerve axons with insulation by a myelin sheath composed largely of different lipids. Recent evidence has indicated that the extent of myelination of nerve axons can adapt based on neural activity levels and this adaptive myelination is associated with improved learning of motor tasks, suggesting such plasticity may enhance effective learning. In this study, we examined whether another aspect of myelin plasticity-changes in myelin lipid synthesis and composition-may also be associated with motor learning. We combined a motor learning task in mice with in vivo two-photon imaging of neural activity in the primary motor cortex (M1) to distinguish early and late stages of learning and then probed levels of some key myelin lipids using mass spectrometry analysis. Sphingomyelin levels were elevated in the early stage of motor learning while galactosylceramide levels were elevated in the middle and late stages of motor learning, and these changes were correlated across individual mice with both learning performance and neural activity changes. Targeted inhibition of oligodendrocyte-specific galactosyltransferase expression, the enzyme that synthesizes myelin galactosylceramide, impaired motor learning. Our results suggest regulation of myelin lipid composition could be a novel facet of myelin adaptations associated with learning.

CD34+/CD144+ circulating endothelial cells as an indicator of carotid atherosclerosis.

BACKGROUND: The relationships between the number of circulating endothelial cells (CECs) or endothelial progenitor cells (EPCs) and indicators of carotid atherosclerosis, such as the intima-media thickness (IMT) and plaque score are not well characterized in patients with chronic ischemic stroke. The objective of this study was to investigate these relationships in patients with chronic ischemic stroke and in patients with risk factors for stroke. METHODS: A total of 58 patients (69.6 ± 10.0 years, 21 females) with chronic ischemic stroke or with risk factors for stroke were included in this study. IMT was measured using an IntimaScope, and the numbers of CECs and EPCs were measured using flow cytometry. CECs and EPCs were defined as CD34+/CD144+ and CD34+/CD133+ cells, respectively. RESULTS: The number of CECs in patients with large artery atherosclerosis was higher than that in patients with cardioembolism or small vessel occlusion (P < .05). In contrast, there were no significant differences in the number of EPCs between groups. A positive correlation was also observed between the plaque score and the number of CECs (r(2) = .139, P < .05, n = 36). Moreover, the number of CECs in patients with moderate and severe atherosclerosis (.32 ± .11/µL, n = 22) was higher than that in patients with no plaque and mild atherosclerosis (.25 ± .07/µL, n = 34, P < .05). CONCLUSIONS: The number of CECs was high in patients with large artery atherosclerosis who experienced chronic ischemic stroke. And this number may reflect severity of carotid atherosclerosis.

[Management of stroke in patients with diabetes mellitus].

Diabetes mellitus is an independent risk factor for ischemic stroke. Medical interview, physical, neurological, and radiological examination are performed for diagnosis of stroke. CT, MRI, MRA, CT angiography, and carotid ultrasonography are used for classification of type of ischemic stroke. Immediate treatment using such as rt-PA or endovascular therapy improves the prognosis. Antiplatelet therapy is recommended for purposes of risk reduction of recurrent stroke, but blood sugar control is uncertain.

Fiber type-specific expression of low-density lipoprotein receptor-related protein 6 in human skeletal muscles.

OBJECTIVE: Gene expression patterns differ in the two types of skeletal muscle fiber. The Wnt signaling pathway, which includes low-density lipoprotein receptor-related protein 6 (LRP6), has been associated with cell differentiation and glucose metabolism in skeletal muscles. We examined the relationships between muscle fiber types and LRP6 expression. METHODS: Adenosine triphosphatase was assayed histochemically, and the levels of expression of LRP6 and myosin were analyzed immunohistochemically, in frozen sections of muscle fiber obtained from 16 muscle biopsy samples. The expression pattern of LRP6 in C2C12 cells was assayed by immunocytochemistry. RESULTS: LRP6 was expressed only in type II fibers. Type IIc fibers showed variations in LRP6 expression. Expression of LRP6 was observed at the stage of myoblast differentiation. CONCLUSION: Antibody to LRP6 may be useful for identifying type II skeletal muscle fibers. LRP6 may influence glucose metabolism in type II fibers of human skeletal muscles.

Isolated unilateral hypoglossal nerve paralysis caused by internal carotid artery dissection.

We here report the case of isolated hypoglossal nerve paralysis. Magnetic resonance imaging demonstrated characteristic findings of internal carotid artery dissection that should be considered as one of the differential diagnosis of ipsilateral pure hypoglossal nerve paralysis.

Safety evaluation of substituting clopidogrel for ticlopidine in Japanese patients with ischemic stroke--Hiroshima ticlopidine, clopidogrel safe exchange trial.

BACKGROUND: Clopidogrel is sometimes substituted for ticlopidine when cerebrovascular or cardiovascular patients develop hematologic abnormalities after ticlopidine treatment. However, the adverse event rate after the substitution to clopidogrel remains undetermined. Therefore, in this study, we aimed to define the risk of adverse events after substituting clopidogrel for ticlopidine without a washout period. METHODS: We prospectively enrolled patients older than 20 years who had a history of noncardioembolic strokes, including transient ischemic attacks, were treated with ticlopidine for at least 6 months. This study was conducted from August 26, 2008, when the first patient was enrolled, to January 16, 2012, the date of the last patient examination, at 8 active stroke centers in Hiroshima, Japan. We excluded patients who had severe disabilities, evidence of cardioembolic stroke, or history of a bleeding event. Each patient received clopidogrel (either 50 mg or 75 mg) once a day in place of ticlopidine without a washout period. Follow-up exams were scheduled within 12 months after the medication substitution. The primary end point of this study was adverse events of interest, including clinically significant reduced blood cell counts, hepatic dysfunction, bleeding, and other serious side effects. RESULTS: In this study, 110 patients were enrolled and analyzed in an intent-to-treat manner (modified intent to treat). Within the scheduled follow-up periods, 9 primary end point events were observed in separate patients. The primary end point events were observed at a rate of 8.4% per year (Kaplan-Meier method). At the time of enrolment, 16 patients met the exclusion criteria, of which 8 recovered from their abnormal hematologic results to the institutional normal limit after the substitution of ticlopidine for clopidogrel (57.4% per year). CONCLUSIONS: The adverse event rates after the substitution of ticlopidine for clopidogrel is similar to the adverse event rates of patients who were initially treated with clopidogrel. The substitution of clopidogrel for ticlopidine should be considered for patients who develop hematologic abnormalities from ticlopidine treatment.

Neuromodulation with transcranial direct current stimulation contributes to motor function recovery via microglia in spinal cord injury.

Spinal cord injury (SCI) is damage or trauma to the spinal cord, which often results in loss of function, sensation, or mobility below the injury site. Transcranial direct current stimulation (tDCS) is a non-invasive and affordable brain stimulation technique used to modulate neuronal circuits, which changes the morphology and activity of microglia in the cerebral cortex. However, whether similar morphological changes can be observed in the spinal cord remains unclear. Therefore, we evaluated neuronal population activity in layer 5 (L5) of M1 following SCI and investigated whether changes in the activities of L5 neurons affect microglia-axon interactions using C57BL/6J mice. We discovered that L5 of the primary motor cortex (corticospinal neurons) exhibited reduced synchronized activity after SCI that correlates with microglial morphology, which was recovered using tDCS. This indicates that tDCS promotes changes in the morphological properties and recovery of microglia after SCI. Combining immunotherapy with tDCS may be effective in treating SCI.

A dopamine D1-like receptor-specific agonist improves the survival of septic mice.

In this study, a murine sepsis model was developed using the cecum ligation and puncture (CLP) technique. The expression of the proinflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin-1ß (IL-1ß) in the brain increased 6 h after CLP but decreased 24 h later when elevated endogenous dopamine levels in the brain were sustained. Methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride reduced dopamine levels in the striatum and increased mortality in septic mice. Dopamine D1-like receptors were significantly expressed in the brain, but not in the lungs. Intraperitoneally administered SKF-81297 (SKF), a blood-brain barrier-permeable D1-like receptor agonist, prevented CLP-induced death of septic mice with ameliorated acute lung injury and cognitive dysfunction and suppressed TNF-α and IL-1ß expression. The D1-like receptor antagonist SCH-23390 abolished the anti-inflammatory effects of SKF. These data suggest that D1-like receptor-mediated signals in the brain prevent CLP-induced inflammation in both the brain and the periphery.

Recurrent embolic strokes associated with vertical atlantoaxial subluxation in a patient with rheumatoid arthritis: a case report and review of literature.

We report a 78-year-old woman with rheumatoid arthritis who developed recurrent embolic cerebellar strokes associated with vertical atlantoaxial subluxation (AAS). On contrast angiography, the bilateral vertebral arteries (VAs) were occluded between the C1 and C2 levels, and the distal parts of bilateral VA were supplied by the collateral circulations. Dynamic cerebral angiography and carotid duplex ultrasonography showed that blood flow was substantially decreased in the left VA and left posterior inferior cerebellar artery on cervical anteflexion. It is suggested that vertical AAS reduced the blood flow of collateral circulation in the left VA with cervical anteflexion and might be a cause of recurrent ischemic stroke.

[Remodeling of Neuronal Circuits in Chronic Pain].

Chronic pain is associated with various brain malfunctions, such as allodynia and anxiety. The underlying mechanism is a long-term alteration of neural circuits in the related brain regions. Here, we focus on the contribution of glial cells to build up pathological circuits. In addition, an attempt to enhance the neuronal plasticity of the pathological circuits to repair them to relieve abnormal pain will be introduced. The possible clinical applications will also be discussed.

[Microglial regulation of brain function and pathological changes].

Microglia are the only immune cells in the central nervous system. It has been shown that microglia actively regulate the number of neurons by participating in the cell death of neural stem cells during development and maturation. In addition, recent optical techniques have enabled in vivo imaging, which has revealed the function of microglia on synapses. Microglia regularly monitor synaptic activity and remove synapses that show abnormal activity in the event of brain infarction or other disorders. During development, microglia contribute to the formation of immature synapses by contacting dendrites during early synapse formation, and they are also involved in the de-synaptic process by selectively removing weakly active synapses through the use of classical complement cascade signaling. Furthermore, these abnormalities are known to contribute to the development of autism during development and to the development of Alzheimer's disease during maturation. In addition to this, microglia also contribute to plastic changes in synapses during the learning process in maturation. Furthermore, by modifying synaptic activity, microglia are known to be involved in changes in the activity of neuronal circuits. In addition to these synaptic functions, microglia are also known to be involved in the permeability of the blood-brain barrier. In this chapter, these functions will be summarized and discussed.

Activity-dependent oligodendrocyte calcium dynamics and their changes in Alzheimer's disease.

Oligodendrocytes (OCs) form myelin around axons, which is dependent on neuronal activity. This activity-dependent myelination plays a crucial role in training and learning. Previous studies have suggested that neuronal activity regulates proliferation and differentiation of oligodendrocyte precursor cells (OPCs) and myelination. In addition, deficient activity-dependent myelination results in impaired motor learning. However, the functional response of OC responsible for neuronal activity and their pathological changes is not fully elucidated. In this research, we aimed to understand the activity-dependent OC responses and their different properties by observing OCs using in vivo two-photon microscopy. We clarified that the Ca2+ activity in OCs is neuronal activity dependent and differentially regulated by neurotransmitters such as glutamate or adenosine triphosphate (ATP). Furthermore, in 5-month-old mice models of Alzheimer's disease, a period before the appearance of behavioral abnormalities, the elevated Ca2+ responses in OCs are ATP dependent, suggesting that OCs receive ATP from damaged tissue. We anticipate that our research will help in determining the correct therapeutic strategy for neurodegenerative diseases beyond the synapse.

Microglia enable cross-modal plasticity by removing inhibitory synapses.

Cross-modal plasticity is the repurposing of brain regions associated with deprived sensory inputs to improve the capacity of other sensory modalities. The functional mechanisms of cross-modal plasticity can indicate how the brain recovers from various forms of injury and how different sensory modalities are integrated. Here, we demonstrate that rewiring of the microglia-mediated local circuit synapse is crucial for cross-modal plasticity induced by visual deprivation (monocular deprivation [MD]). MD relieves the usual inhibition of functional connectivity between the somatosensory cortex and secondary lateral visual cortex (V2L). This results in enhanced excitatory responses in V2L neurons during whisker stimulation and a greater capacity for vibrissae sensory discrimination. The enhanced cross-modal response is mediated by selective removal of inhibitory synapse terminals on pyramidal neurons by the microglia in the V2L via matrix metalloproteinase 9 signaling. Our results provide insights into how cortical circuits integrate different inputs to functionally compensate for neuronal damage.

Controlled activation of cortical astrocytes modulates neuropathic pain-like behaviour.

Chronic pain is a major public health problem that currently lacks effective treatment options. Here, a method that can modulate chronic pain-like behaviour induced by nerve injury in mice is described. By combining a transient nerve block to inhibit noxious afferent input from injured peripheral nerves, with concurrent activation of astrocytes in the somatosensory cortex (S1) by either low intensity transcranial direct current stimulation (tDCS) or via the chemogenetic DREADD system, we could reverse allodynia-like behaviour previously established by partial sciatic nerve ligation (PSL). Such activation of astrocytes initiated spine plasticity to reduce those synapses formed shortly after PSL. This reversal from allodynia-like behaviour persisted well beyond the active treatment period. Thus, our study demonstrates a robust and potentially translational approach for modulating pain, that capitalizes on the interplay between noxious afferents, sensitized central neuronal circuits, and astrocyte-activation induced synaptic plasticity.

[Clinical characteristics of ischemic stroke in elderly patients with cancer].

AIM: We classified acute ischemic stroke patients with cancer according to their causal relations, and attempted to evaluate the clinical characteristics of ischemic stroke associated with cancer. METHODS: This is a retrospective study of all acute ischemic stroke patients admitted to our hospital between January 2006 and March 2009. Among acute ischemic stroke patients, we identified 30 patients with a history of cancer, or who developed cancer within 1 year from their ischemic stroke onset. There were 2 patients excluded from our evaluation because they had undergone extirpation of their cancer more than 5 years before stroke onset, and no recurrence of cancer within 5 years of stroke onset was noted. Finally, 28 patients were enrolled and evaluated in this study. Ischemic stroke was classified based on the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. In addition, we classified the patients according to their causal relations of ischemic stroke with cancer. RESULTS: The median patient age was 74 years (range, 56 to 91 years); 68% of patients were men. Of these, 8 (29%) were classified into an ischemic stroke related to cancer group. There was a higher prevalence of ischemic stroke related to cancer in patients under 75 years old with clinical stage IV cancer (p=0.02). D-dimer tended to be higher in those patients with ischemic stroke related to cancer in this study (p=0.13). CONCLUSION: Ischemic stroke related to cancer was found more frequently in patients under 75 years old with advanced cancer. Additionally, D-dimer tended to be higher in those patients with ischemic stroke related to cancer.

Overexpression of neuronal K+-Cl- co-transporter enhances dendritic spine plasticity and motor learning.

The neuronal K+-Cl- cotransporter KCC2 maintains a low intracellular Cl- concentration and facilitates hyperpolarizing GABAA receptor responses. KCC2 also plays a separate role in stabilizing and enhancing dendritic spines in the developing nervous system. Using a conditional transgenic mouse strategy, we examined whether overexpression of KCC2 enhances dendritic spines in the adult nervous system and characterized the effects on spine dynamics in the motor cortex in vivo during rotarod training. Mice overexpressing KCC2 showed significantly increased spine density in the apical dendrites of layer V pyramidal neurons, measured in vivo using two-photon imaging. During modest accelerated rotarod training, mice overexpressing KCC2 displayed enhanced spine formation rates, greater balancing skill at higher rotarod speeds and a faster rate of learning in this ability. Our results demonstrate that KCC2 enhances spine density and dynamics in the adult nervous system and suggest that KCC2 may play a role in experience-dependent synaptic plasticity.

The roles of cortical astrocytes in chronic pain and other brain pathologies.

Astrocytes are the most abundant cell type in the brain. Several decades ago, they were considered to be only support cells in the central nervous system. Recent studies using advanced technologies have clarified that astrocytes play more active roles in regulating neuronal function and remodeling synaptic structures by releasing molecules called gliotransmitters. In addition to various physiological functions, astrocytes are activated under disease conditions, such as chronic pain, releasing molecules that in turn cause reorganization of the central nervous system microstructure and disrupt behavior in pathological conditions. In the present review, we summarize cortical astrocyte function in chronic pain and other neurological disorders and discuss the role of astrocytes in brain pathologies.

Cortical astrocytes prime the induction of spine plasticity and mirror image pain.

Peripheral nerve injury causes maladaptive plasticity in the central nervous system and induces chronic pain. In addition to the injured limb, abnormal pain sensation can appear in the limb contralateral to the injury, called mirror image pain. Because synaptic remodeling in the primary somatosensory cortex (S1) has critical roles in the induction of chronic pain, cortical reorganization in the S1 ipsilateral to the injured limb may also accompany mirror image pain. To elucidate this, we conducted in vivo 2-photon calcium imaging of neuron and astrocyte activity in the ipsilateral S1 after a peripheral nerve injury. We found that cross-callosal inputs enhanced the activity of both S1 astrocytes and inhibitory neurons, whereas activity of excitatory neurons decreased. When local inhibitory circuits were blocked, astrocyte-dependent spine plasticity and allodynia were revealed. Thus, we propose that cortical astrocytes prime the induction of spine plasticity and mirror image pain after peripheral nerve injury. Moreover, this result suggests that cortical synaptic rewiring could be sufficient to cause allodynia on the uninjured periphery.

Neurological Complications in Eosinophilic Granulomatosis with Polyangiitis (EGPA): The Roles of History and Physical Examinations in the Diagnosis of EGPA.

Objective To investigate the clinical symptoms, the physical and neurological findings, and the clinical course of neurological complications in eosinophilic granulomatosis with polyangiitis (EGPA). Methods A retrospective chart review of EGPA cases managed by two referral hospitals was performed, with a focus on the neurological findings. The study analyzed the symptoms at the onset of EGPA and investigated their chronological relationship. The patient delay (the delay between the onset of symptoms and the initial consultation), and the physician delay (the delay from consultation to the initiation of therapy) were determined and compared. The involved nerves were identified thorough a neurological examination. The cases with central nervous system (CNS) involvement were described. Results The average duration of symptoms prior to the initiating of therapy for sensory disturbances, motor deficits, rash, edema, and fever was 23, 5, 21, 18, and 24 days, respectively. Among the EGPA-specific symptoms, sensory disturbance was often the first symptom (63%), and was usually followed by the appearance of rash within four days (63%). The average physician delay (32.9±38.3 days) was significantly longer than the average patient delay (7.9±7.8 days; p=0.010). Reduced touch sensation in the superficial peroneal area, and weakness of dorsal flexion of the first toe secondary to deep peroneal nerve involvement, were highly sensitive for identifying the presence of peripheral nerve involvement in our series of patients with EGPA. Two cases, with CNS involvement, had multiple skin lesions over their hands and feet (Janeway lesions). Conclusion Japanese physicians are not always familiar with EGPA. It is important for us to consider this disease, when an asthmatic patient complains about the new onset of an abnormal sensation in the distal lower extremities, which is followed several days later by rash.

A case of chronic inflammatory demyelinating polyradiculoneuropathy after treatment with pegylated interferon α-2a in a patient with chronic hepatitis B virus infection.

We report the case of a 42-year-old man with chronic hepatitis B virus infection who developed weakness and paresthesia in the extremities 2 months after administration of pegylated interferon (Peg-IFN)α-2a. Nerve conduction studies conducted 6 months after onset showed abnormal temporal dispersions in both tibial nerves. We diagnosed chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) resulting from treatment with Peg-IFNα-2a. Neurological symptoms were prolonged despite suspension of the treatment. Subsequent treatment with intravenous immunoglobulin improved both clinical symptoms and temporal dispersion. IFNα-induced CIDP is rare, but can reportedly progress even after interruption of IFN-α without immunotherapy. Patients presenting with polyneuropathy after initiation of IFN-α thus require close attention.