Kodai Kume

Nitric oxide-mediated modulation of calcium/calmodulin-dependent protein kinase II.

The mechanisms of NO inhibition of CaMK [Ca(2+)/CaM (calmodulin)-dependent protein kinase] II activity were studied. In rat pituitary tumour GH3 cells, TRH [thyrotrophin (TSH)-releasing hormone]-stimulated phosphorylation of nNOS [neuronal NOS (NO synthase)] at Ser(847) was sensitive to an inhibitor of CaMKs, KN-93, and was enhanced by inhibition of nNOS with 7NI (7-nitroindazole). Enzyme activity of CaMKII following in situ treatment with 7NI was also increased. The in vitro activity of CaMKII was inhibited by co-incubation either with nNOS and L-arginine or with NO donors SNAP (S-nitroso-N-acetyl-DL-penicillamine) and DEA-NONOate [diethylamine-NONOate (diazeniumdiolate)]. Once inhibited by these treatments, CaMKII was observed to undergo full reactivation on the addition of a reducing reagent, DTT (dithiothreitol). In transfected cells expressing CaMKII and nNOS, treatment with the calcium ionophore A23187 further revealed nNOS phosphorylation at Ser(847), which was enhanced by 7NI and CaMKII S-nitrosylation. Mutated CaMKII (C6A), in which Cys(6) was substituted with an alanine residue, was refractory to 7NI-induced enhancement of nNOS phosphorylation or to CaMKII S-nitrosylation. Furthermore, we could identify Cys(6) as a direct target for S-nitrosylation of CaMKII using MS. In addition, treatment with glutamate caused an increase in CaMKII S-nitrosylation in rat hippocampal slices. This glutamate-induced S-nitrosylation was blocked by 7NI. These results suggest that inactivation of CaMKII mediated by S-nitrosylation at Cys(6) may contribute to NO-induced neurotoxicity in the brain.

Inhibition of neuronal nitric-oxide synthase by phosphorylation at Threonine1296 in NG108-15 neuronal cells.

We demonstrate that neuronal nitric‐oxide synthase (nNOS) is directly inhibited through the phosphorylation of Thr1296 in NG108‐15 neuronal cells. Treatment of NG108‐15 cells expressing nNOS with calyculin A, an inhibitor of protein phosphatase 1 and 2A, revealed a dose‐dependent inhibition of nNOS enzyme activity with concomitant phosphorylation of Thr1296 residue. Cells expressing a phosphorylation‐deficient mutant in which Thr1296 was changed to Ala proved resistant to phosphorylation and suppression of NOS activity. Mimicking phosphorylation mutant of nNOS in which Thr1296 is changed to Asp showed a significant decrease in nNOS enzyme activity, being competitive with NADPH, relative to the wild‐type enzyme. These data suggest that phosphorylation of nNOS at Thr1296 may involve the attenuation of nitric oxide production in neuronal cells through the decrease of NADPH‐binding to the enzyme.

p90 RSK-1 associates with and inhibits neuronal nitric oxide synthase

Evidence is presented that RSK1 (ribosomal S6 kinase 1), a downstream target of MAPK (mitogen-activated protein kinase), directly phosphorylates nNOS (neuronal nitric oxide synthase) on Ser847 in response to mitogens. The phosphorylation thus increases greatly following EGF (epidermal growth factor) treatment of rat pituitary tumour GH3 cells and is reduced by exposure to the MEK (MAPK/extracellular-signal-regulated kinase kinase) inhibitor PD98059. Furthermore, it is significantly enhanced by expression of wild-type RSK1 and antagonized by kinase-inactive RSK1 or specific reduction of endogenous RSK1. EGF treatment of HEK-293 (human embryonic kidney) cells, expressing RSK1 and nNOS, led to inhibition of NOS enzyme activity, associated with an increase in phosphorylation of nNOS at Ser847, as is also the case in an in vitro assay. In addition, these phenomena were significantly blocked by treatment with the RSK inhibitor Ro31-8220. Cells expressing mutant nNOS (S847A) proved resistant to phosphorylation and decrease of NOS activity. Within minutes of adding EGF to transfected cells, RSK1 associated with nNOS and subsequently dissociated following more prolonged agonist stimulation. EGF-induced formation of the nNOS-RSK1 complex was significantly decreased by PD98059 treatment. Treatment with EGF further revealed phosphorylation of nNOS on Ser847 in rat hippocampal neurons and cerebellar granule cells. This EGF-induced phosphorylation was partially blocked by PD98059 and Ro31-8220. Together, these data provide substantial evidence that RSK1 associates with and phosphorylates nNOS on Ser847 following mitogen stimulation and suggest a novel role for RSK1 in the regulation of nitric oxide function in brain.

Neuromyelitis optica spectrum disorder presenting with repeated hypersomnia due to involvement of the hypothalamus and hypothalamus-amygdala linkage.

We report the case of a 46-year-old Japanese woman with neuromyelitis optica spectrum disorder presenting with repeated hypersomnia accompanied by decreased CSF orexin level. First episode associated with hypothalamic-pituitary dysfunction showed bilateral hypothalamic lesions that can cause secondary damage to the orexin neurons. The second episode associated with impaired memory showed a left temporal lesion involving the amygdala. The mechanism remains unknown, but the reduced blood flow in the hypothalamus ipsilateral to the amygdala lesion suggested trans-synaptic hypothalamic dysfunction secondary to the impaired amygdala. A temporal lesion involving the amygdala and hypothalamus could be responsible for hypersomnia due to neuromyelitis optica spectrum disorder.

Serum microRNA expression profiling in patients with multiple system atrophy

Multiple system atrophy (MSA) is a sporadic neurodegenerative disease that is pathologically characterized by α-synuclein positive glial cytoplasmic inclusions in oligodendrocytes. The clinical diagnosis of MSA is often challenging as there are no established biomarkers and diagnoses are now based on clinical findings alone. At present, the etiology and pathogenesis of MSA are unclear. It has been reported that dysregulation of microRNA (miRNA/miR) serves an important role in neurodegenerative disorders including Alzheimers disease, Parkinsons disease and amyotrophic lateral sclerosis. The miRNA profile of patients with MSA remains to be established. The present study investigated the serum miRNA expression level of 10 patients with MSA, using microarray chips including 668 miRNAs. It was identified that 50 miRNAs were significantly upregulated and 17 miRNAs were significantly downregulated in the serum of the patients with MSA. The most upregulated miRNA was miR-16, which may induce the accumulation of α-synuclein. The target genes of some miRNAs upregulated in MSA (including miR-17, 20a, 24, 25, 30d and 451) were associated with autophagy-associated molecules. The present study concluded that the expression pattern of miRNAs may be a clinical biomarker for MSA and targeting these miRNAs may provide a novel treatment for MSA.

Assessment of sensory perception and processing using current perception threshold in Parkinson's disease

Although peripheral deafferentation is one of the causes of abnormal sensory processing in Parkinsons disease (PD), functional assessment of different‐size sensory nerve populations remains insufficient.

Transcranial Magnetic Stimulation with the Maximum Voluntary Muscle Contraction Facilitates Motor Neuron Excitability and Muscle Force

Three trials of transcranial magnetic stimulation (TMS) during the maximum voluntary muscle contraction (MVC) were repeated at 15-minute intervals for 1 hour to examine the effects on motor evoked potentials (MEPs) in the digital muscles and pinching muscle force before and after 4 high-intensity TMSs (test 1 condition) or sham TMS (test 2 condition) with MVC. Under the placebo condition, real TMS with MVC was administered only before and 1 hour after the sham TMS with MVC. Magnetic stimulation at the foramen magnum level (FMS) with MVC was performed by the same protocol as that for the test 2 condition. As a result, MEP sizes in the digital muscles significantly increased after TMS with MVC under test conditions compared with the placebo conditions (P < 0.05). Pinching muscle force was significantly larger 45 minutes and 1 hour after TMS with MVC under the test conditions than under the placebo condition (P < 0.05). FMS significantly decreased MEP amplitudes 60 minutes after the sham TMS with MVC (P < 0.005). The present results suggest that intermittently repeated TMS with MVC facilitates motor neuron excitabilities and muscle force. However, further studies are needed to confirm the effects of TMS with MVC and its mechanism.

Advantage of 11C-methionine positron emission tomography for assessing IgG4-related central nervous system lesions

Although IgG4-related central nervous system (CNS) lesions are typified by infundibular hypophysitis [1], hypertrophic pachymeningitis (HPM) and intracerebral inflammatory pseudotumor (IIP) have been reported [2–9]. These lesions are usually assessed by MRI with contrast. F-fluorodeoxy-glucose (FDG) or C-methionine (MET) positron emission tomography (PET) has been described as a promising modality for IgG4-related HPM [7, 9], but a comparative study of FDG-PET and MET-PET in the same patients has not been conducted. We describe an advantage of MET over FDG in a patient with IgG4-related HPM and IIP complicated by otitis media and mastoiditis. A 70-year-old woman was admitted to our hospital in July 2011 for the management of ataxic gait and brain lesions on MRI. Thirteen months earlier, she had developed bilateral hearing loss. Five months earlier, steroid therapy based on the diagnosis of autoimmune otitis media was ineffective. Around that time, she wobbled a bit when walking. Brain MRI showed a high-intensity lesion on fluid-attenuated inversion recovery (FLAIR) imaging in the left parieto-occipital region. On admission, she was afebrile; no abnormal findings in general physical examination. Neurological examinations revealed cerebellar ataxia. Pure tone audiometry showed elevated threshold (right: 108.3 dB, left: 115 dB). Laboratory tests revealed a slight elevation in serum total IgG (1,688 mg/dl) but not in IgG4 (67.5 mg/dl). The major autoantibodies and fungal markers were all negative. Her CSF showed elevated protein (79 mg/dl) without pleocytosis. ACE and sIL-2R in the serum and CSF were normal. Brain MRI revealed parenchymal hyperintensities on FLAIR imaging in the right cerebellar hemisphere and the left frontal and parietooccipital regions (Fig. 1). Thickening of the dura mater adjacent to these lesions was suspected, but MRI with contrast was contraindicated for her asthma. With a 64-slice PET/CT scanner (Biograph mCT; Siemens, Hoffman Estates, IL, USA) with a spatial resolution of 4.27 mm, MET-PET was obtained first, considering the short half-life of C. FDG-PET was then performed on the same day. Although the FDG accumulation was observed corresponding to the suspected dura mater thickening on MRI, it was not easy to differentiate the pathological lesions from normal cortex. The uptake of MET in the dura mater and bilateral mastoids was more clear and intense than that of FDG. Neither FDG nor MET accumulated in the parenchymal lesions (Fig. 1, Table 1). Biopsy of the dura mater and left middle ear showed marked lymphocyte infiltration and fibrosis. Infiltration of IgG4 ? plasma cells was observed in the dura mater [ratio of IgG4 ?/ IgG ? cells (68 %) and IgG4 ? plasma cells counts (83/ high power field)] but not in the middle ear. According to the IgG4-related disease diagnostic criteria, the diagnosis K. Kume K. Deguchi (&) T. Masaki Department of Gastroenterology and Neurology, Kagawa University Faculty of Medicine, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, Japan e-mail: kdeguchi@med.kagawa-u.ac.jp

Subacute Sensorimotor Neuropathy Accompanied by Anti-ganglioside GM1 Antibody in a Patient with Lung Cancer

A 66-year-old man presented with subacute sensorimotor neuropathy in association with small cell lung cancer. Tests for the anti-ganglioside antibody GM1-IgM were positive. Chemotherapy and intravenous immunoglobulin treatment led to a slight improvement in neurological symptoms. Four additional cases of neuropathy accompanied by anti-ganglioside antibody and lung cancer have been reported. The most commonly reported pattern was subacute sensorimotor neuropathy. Patients died from cancer progression after 5 to 18 months. There is evidence that anti-ganglioside antibody inhibits tumor progression, prolonging the patient survival. However, severe neurological disturbance may offset the survival benefit of anti-ganglioside antibody in patients with paraneoplastic neurological syndrome.

Dialysis-induced Subdural Hematoma in an Arachnoid Cyst Associated with Autosomal Dominant Polycystic Kidney Disease.

Arachnoid cyst (AC) is a neurological complication of autosomal dominant polycystic kidney disease (ADPKD). Although an AC can increase the risk of a subdural hematoma, the clinical presentation of bleeding into an AC associated with ADPKD is not well known. We herein report the case of a 59-year-old woman in whom the initiation of hemodialysis for renal failure led to AC bleeding. A change of anticoagulant from heparin to nafamostat mesilate allowed dialysis to continue without rebleeding. These findings suggest that hemodialysis in patients with an AC associated with ADPKD may increase the risk of bleeding. Nafamostat mesilate may be useful in such cases.