Publications by authors named "Koji Ikezoe"

A 52-year-old man had developed hearing loss since childhood, as well as recurrent foot ulcers and osteomyelitis since his forties. He presented with gait disturbance and dysarthria that had worsened over four years and a month, respectively. Neurological exams revealed cognitive impairment, proximal weakness of the lower extremities, generalized hyperrflexia, ataxia, sensory disturbances predominant in deep sensation, urinary retention, and gait instability.

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Cerebellar climbing fibers convey sensorimotor information and their errors, which are used for motor control and learning. Furthermore, they represent reward-related information. Despite such functional diversity of climbing fiber signals, it is still unclear whether each climbing fiber conveys the information of single or multiple modalities and how the climbing fibers conveying different information are distributed over the cerebellar cortex.

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Background: Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant muscular disorder characterized by asymmetric muscle wasting and weakness. FSHD can be subdivided into two types: FSHD1, caused by contraction of the D4Z4 repeat on chromosome 4q35, and FSHD2, caused by mild contraction of the D4Z4 repeat plus aberrant hypomethylation mediated by genetic variants in SMCHD1, DNMT3B, or LRIF1. Genetic diagnosis of FSHD is challenging because of the complex procedures required.

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Reaching, grasping, and retrieving movements are essential to our daily lives and are common in many mammalian species. To understand the mechanism for controlling this movement at the neural circuit level, it is necessary to observe the activity of individual neurons involved in the movement. For stable electrophysiological or optical recordings of neural activity in a behaving animal, head fixation effectively minimizes motion artifacts.

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Natural scenes are characterized by diverse image statistics, including various parameters of the luminance histogram, outputs of Gabor-like filters, and pairwise correlations between the filter outputs of different positions, orientations, and scales (Portilla-Simoncelli statistics). Some of these statistics capture the response properties of visual neurons. However, it remains unclear to what extent such statistics can explain neural responses to natural scenes and how neurons that are tuned to these statistics are distributed across the cortex.

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Orientation preference maps (OPMs) are a prominent feature of primary visual cortex (V1) organization in many primates and carnivores. In rodents, neurons are not organized in OPMs but are instead interspersed in a "salt and pepper" fashion, although clusters of orientation-selective neurons have been reported. Does this fundamental difference reflect the existence of a lower size limit for orientation columns (OCs) below which they cannot be scaled down with decreasing V1 size? To address this question, we examined V1 of one of the smallest living primates, the 60-g prosimian mouse lemur (Microcebus murinus).

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In vivo calcium (Ca) imaging using two-photon microscopy allows activity to be monitored simultaneously from hundreds of individual neurons within a local population. While this allows us to gain important insights into how cortical neurons represent sensory information, factors such as photo-bleaching of the Ca indicator limit imaging duration (and thus the numbers of stimuli that can be tested), which in turn hampers the full characterization of neuronal response properties. Here, we demonstrate that using an encoding model combined with presentation of natural movies results in detailed characterization of receptive field (RF) properties despite the relatively short time for data collection.

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Article Synopsis
  • Establishes that precise neuronal connectivity in the neocortex during postnatal development relies on how circuits are reorganized through activity, which is not well understood.
  • Shows that during the first week after birth, layer 4 (L4) neurons in the barrel cortex fire together in a spontaneous "patchwork" pattern without external stimulation, reflecting the barrel map's structure.
  • Indicates this patchwork activity diminishes around week 2 of postnatal development and plays a key role in refining thalamocortical circuits in the neonatal barrel cortex, although it is mostly unaffected by whisker movements and can be reduced by anesthesia.
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Article Synopsis
  • This study aimed to investigate the presence of anti-neurofascin 155 (NF155) antibodies in patients with chronic inflammatory demyelinating polyneuropathy (CIDP).
  • Researchers analyzed serum samples from various patient groups, including those with CIDP, multiple sclerosis, other neuropathies, and healthy controls, to identify the anti-NF antibodies.
  • The results showed that 18% of CIDP patients tested positive for anti-NF155 antibodies, which were linked to younger onset age and specific clinical features like gait disturbances and distinct imaging findings, indicating a unique subset within CIDP patients.
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A majority of neurons in the monkey primary visual cortex (V1) are tuned to stimulus orientations. Preferred orientations and tuning strengths vary among V1 neurons. The preferred orientation of neurons gradually changes across the cortex with occasional failures of this organization.

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The ability to detect and discriminate sensory stimuli greatly improves with age. To better understand the neural basis of perceptual development, we studied the postnatal development of sensory responses in cortical neurons. Specifically, we analyzed neuronal responses to single-whisker deflections in the posteromedial barrel subfield (PMBSF) of the rat primary somatosensory cortex.

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In the primary visual cortex (V1) of some mammals, columns of neurons with the full range of orientation preferences converge at the center of a pinwheel-like arrangement, the 'pinwheel center' (PWC). Because a neuron receives abundant inputs from nearby neurons, the neuron's position on the cortical map likely has a significant impact on its responses to the layout of orientations inside and outside its classical receptive field (CRF). To understand the positional specificity of responses, we constructed a computational model based on orientation preference maps in monkey V1 and hypothetical neuronal connections.

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Thalamocortical afferents innervate both excitatory and inhibitory cells, the latter in turn producing disynaptic feedforward inhibition, thus creating fast excitation-inhibition sequences in the cortical cells. Since this inhibition is disynaptic, the time lag of the excitation-inhibition sequence could be approximately 2-3 ms, while it is often as short as only slightly above 1 ms; the mechanism and function of such fast IPSPs are not fully understood. Here we show that thalamic activation of inhibitory neurons precedes that of excitatory neurons, due to increased conduction velocity of thalamic axons innervating inhibitory cells.

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Chloroquine, an anti-malaria drug, is known to cause myopathy with rimmed vacuole formation. Although it disrupts the lysosomal degradation of proteins, the precise mechanism underlying muscle fiber degeneration has remained unclear. We investigated the temporal profiles of muscle fiber degeneration in chloroquine-treated rats, paying special attention to endoplasmic reticulum (ER) stress and autophagy.

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We report a 72-year-old man with eosinophilic myositis (EM). At age 71 he noticed a painful nodule in his left calf. A biopsy (first biopsy) showed marked infiltration of mononucleated cells and necrotic muscle fibers.

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Fibrodysplasia ossificans progressiva (FOP) is a rare autosomal dominant congenital disease characterized by progressive heterotopic endochondral osteogenesis with great-toe malformations. A 617G > A (R206H) mutation of the activin A type 1 receptor gene (ACVR1) has been found in all previously reported patients with FOP. Thus, this is one of the most specific of all disease-associated mutations.

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In myotonic dystrophy type 1 (DM1), alternative splicing of ryanodine receptor 1 (RyR1) and sarcoplasmic/endoplasmic reticulum Ca2+ ATPase (SERCA) genes has been reported. These proteins are essential for maintaining intracellular Ca2+ in skeletal muscle. To clarify involvement of endoplasmic reticulum (ER) stress in DM1 muscles, we examined the activation of ER stress-related proteins by immunohistochemistry, western blot analysis and RT-PCR.

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An improved method for Southern DNA and Northern RNA blotting using the Mupid-2 Mini-Gel System is described. We get sharp and clear bands in Southern and Northern blotting after only 30 min short gel electrophoresis instead of the several hours large gel electrophoresis of conventional methods. The high electrical voltage with a pulse-like current of the Mupid-2 Mini-Gel System also allows reduction of the amount of formaldehyde, a harmful reagent, from the gel running buffer in RNA blotting.

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Expanded CUG triplet repeats carrying mRNA seem to be responsible for myotonic dystrophy type 1 (DM1). To study the pathogenesis of DM1, we constructed a DM1 cell culture model using a PC12 neuronal cell line and screened flavonoids that ameliorate this mRNA gain of function. The expanded 250 CTG repeat was subcloned into the 3'-untranslated region of the luciferase gene yielding a stable transformant of PC12 (CTG-250).

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The amyloid beta-protein (Abeta) ending at 42 plays a pivotal role in Alzheimer's disease (AD). We have reported previously that intracellular Abeta42 is associated with neuronal apoptosis in vitro and in vivo. Here, we show that intracellular Abeta42 directly activated the p53 promoter, resulting in p53-dependent apoptosis, and that intracellular Abeta40 had a similar but lesser effect.

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A 29-year-old woman with benign congenital nemaline myopathy is reported. She did not walk until the age of one year and seven months. Although she acquired the ability to run, she ran very slowly.

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Article Synopsis
  • A 58-year-old woman developed stiffness, swelling, and muscle pain after climbing a mountain, showing symptoms similar to scleroderma one month later.
  • Lab tests indicated peripheral blood eosinophilia, high inflammation markers, and a positive IgM antibody for Borrelia afzelii.
  • Treatment with prednisolone, doxycycline, and amoxicillin improved her symptoms, marking the first reported case linking Borrelia afzelii to eosinophilic fasciitis.
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We report a 23-year-old man with mitochondrial encephalomyopathy. At 21 years of age, he noted speech distubance. Since his dysarthria did not improve thereafter, he was admitted to our hospital.

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We report a 20-year-old man with temporal lobe epilepsy (TLE) accompanied by hereditary motor and sensory neuropathy (HMSN). He had experienced complex partial seizures (CPS), which started with a nausea-like feeling, followed by loss of consciousness and automatism, since he was 6 years old. The frequency of attacks was at first decreased by phenytoin.

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