248 results on '"Kenichiro, Miura"'
Search Results
202. Early occurrence of nephrotic syndrome associated with cord blood stem cell transplantation
- Author
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Ayaka Furuya, Kenichiro Miura, Kohmei Ida, Junko Takita, Hiroshi Terashima, Takashi Sekine, Masaru Takamizawa, Katsuyoshi Koh, and Takashi Igarashi
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Male ,Nephrology ,medicine.medical_specialty ,Nephrotic Syndrome ,Erythema ,Physiology ,Prednisolone ,medicine.medical_treatment ,Graft vs Host Disease ,chemical and pharmacologic phenomena ,Cord Blood Stem Cell Transplantation ,Hematopoietic stem cell transplantation ,Tacrolimus ,Recurrence ,Oral administration ,Physiology (medical) ,Internal medicine ,Humans ,Medicine ,Child ,Bone Marrow Transplantation ,business.industry ,Remission Induction ,Precursor Cell Lymphoblastic Leukemia-Lymphoma ,medicine.disease ,Surgery ,Pleural Effusion ,Transplantation ,surgical procedures, operative ,Child, Preschool ,medicine.symptom ,business ,Nephrotic syndrome - Abstract
Nephrotic syndrome (NS) associated with hematopoietic stem cell transplantation (HSCT) is usually related to chronic graft-versus-host disease (GVHD) and invariably occurs later than 100 days after transplantation. Here, we report the case of a 6-year-old boy who presented with NS only 61 days after cord blood stem cell transplantation (CBSCT). At 4 years old he was diagnosed with acute lymphoblastic leukemia and underwent bone marrow transplantation. Six months later, a recurrence was noted in the thymus, which required CBSCT at the age of 6. Acute GVHD and hemophagocytic syndrome occurred on day +13 and day +15, respectively, and were successfully treated with tacrolimus and a steroid. After tacrolimus was switched from intravenous infusion to oral administration, NS occurred on day +61. Complete remission was achieved in 3 weeks by resuming steroid treatment. Dry erythema with pigmentation and elevation of Th2 cytokine level suggest that NS in this case was also related to chronic GVHD. To our knowledge, this is the earliest occurrence of NS after HSCT. Hematologists and nephrologists should be aware that this condition may occur even in early periods after HSCT.
- Published
- 2011
203. Difference in perceptual and oculomotor responses revealed by apparent motion stimuli presented with an interstimulus interval
- Author
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Kenichiro Miura, Kenji Kawano, and Shizuka Nohara
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Adult ,Male ,medicine.medical_specialty ,Eye Movements ,Physiology ,media_common.quotation_subject ,Illusion ,Motion Perception ,Audiology ,Sensory Processing ,Motion (physics) ,Functional Laterality ,Contrast Sensitivity ,Motion ,Young Adult ,Perception ,medicine ,Psychophysics ,Reaction Time ,Humans ,media_common ,Communication ,business.industry ,General Neuroscience ,Interstimulus interval ,Eye movement ,Visual motion ,Pattern Recognition, Visual ,Female ,business ,Psychology ,Photic Stimulation - Abstract
To understand the mechanisms underlying visual motion analyses for perceptual and oculomotor responses and their similarities/differences, we analyzed eye movement responses to two-frame animations of dual-grating 3 f5 f stimuli while subjects performed direction discrimination tasks. The 3 f5 f stimulus was composed of two sinusoids with a spatial frequency ratio of 3:5 (3 f and 5 f), creating a pattern with fundamental frequency f. When this stimulus was shifted by 1/4 of the wavelength, the two components shifted 1/4 of their wavelengths and had opposite directions: the 5 f forward and the 3 f backward. By presenting the 3 f5 f stimulus with various interstimulus intervals (ISIs), two visual-motion-analysis mechanisms, low-level energy-based and high-level feature-based, could be effectively distinguished. This is because response direction depends on the relative contrast between the components when the energy-based mechanism operates, but not when the feature-based mechanism works. We found that when the 3 f5 f stimuli were presented with shorter ISIs (100 ms), whereas perceived directions were biased toward the direction of pattern shift. These results suggest that the energy-based mechanism is dominant in oculomotor responses throughout ISIs; however, there is a transition from energy-based to feature-tracking mechanisms when we perceive visual motion.
- Published
- 2014
204. An integrated eye movement score as a neurophysiological marker of schizophrenia
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Yuka Yasuda, Satomi Umeda-Yano, Hidenaga Yamamori, Kazutaka Ohi, Michiko Fujimoto, Masatoshi Takeda, Masaki Fukunaga, Kenichiro Miura, Ryota Hashimoto, and Masao Iwase
- Subjects
Adult ,medicine.medical_specialty ,Adolescent ,Eye Movements ,Schizophrenia (object-oriented programming) ,Severity of Illness Index ,Social Skills ,Young Adult ,Physical medicine and rehabilitation ,Cognition ,Japan ,Medicine ,Humans ,Eye Movement Measurements ,Biological Psychiatry ,Aged ,Psychiatric Status Rating Scales ,business.industry ,Eye movement ,Neurophysiology ,Middle Aged ,Psychiatry and Mental health ,Psychiatric status rating scales ,Schizophrenia ,Schizophrenic Psychology ,business ,Cognitive psychology - Published
- 2014
205. Retinotopic hemodynamic activation of the human V5/MT area during optokinetic responses
- Author
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Toshimitsu Takahashi, Kouki Hashimoto, Shigeru Muraki, Kenji Kansaku, Kenichiro Miura, and Kenji Kawano
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Adult ,Male ,Brain activation ,Visual perception ,Eye Movements ,genetic structures ,General Neuroscience ,Motion Perception ,Hemodynamics ,Optokinetic reflex ,Middle Aged ,Biology ,Magnetic Resonance Imaging ,Retina ,eye diseases ,Visual field ,Peripheral ,Functional imaging ,Retinotopy ,Humans ,Female ,Visual Fields ,Neuroscience ,Photic Stimulation ,Visual Cortex - Abstract
To detect retinotopic activation in the human V5/MT, we obtained fMRI signals during optokinetic responses (OKR). We used two types of patterns, consisting of random dots plotted in either the central or peripheral regions, to stimulate the central and peripheral visual fields, respectively. These patterns moved at a constant speed of 20 degrees/s rightward and leftward alternately. Subjects were required to track the patterns with their eyes. The two types of visual stimuli elicited different patterns of brain activation; the area with the most significant response to central visual field stimuli was located posteriorly to that responding to peripheral visual field stimuli.
- Published
- 2001
206. Initiation of smooth pursuit in humans
- Author
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Kenji Kawano, Kazuyo Suehiro, Yasushi Kodaka, Miyuki Yamamoto, and Kenichiro Miura
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Physics ,genetic structures ,Pursuit eye movement ,business.industry ,General Neuroscience ,Eye movement ,Centripetal force ,Smooth pursuit ,Eye position ,Optics ,Salience (neuroscience) ,Visual attention ,Computer vision ,Artificial intelligence ,business - Abstract
We examined the influence of target saliency on the initiation of smooth pursuit. The eye movements of five human subjects were recorded with the scleral search-coil technique. A video-projection system was used to create a pursuit target, consisting of a cluster of 14 red or green dots (0.5° squares) extending randomly over a 3°×3° region, and a surrounding background, consisting of stationary, random dots of the same size and density extending over an area 70°×40°. When the dots in the background and the target were of the same color, the target was indistinguishable from the background until it started to move. On the other hand, when the colors were different, the target was salient, even when stationary. We measured the changes in eye position over the 70-ms interval starting 70 ms after the onset of target motion (initial tracking response). When the target moved toward the fovea (centripetal motion), the initial tracking responses developed earlier when the dots in the target and background were of different color than when the two sets of dots were of the same color. However, in order to see this effect of target salience, it was critical that the colors be different before the onset of motion, but not afterwards. When the target moved away from the fovea (centrifugal motion), the initial tracking responses were independent of whether the colors of the target and the background were the same or different. Our data indicate that the initiation of tracking responses is very sensitive to the saliency of the target before the onset of target motion when that motion is toward the fovea.
- Published
- 2001
207. A case of adult Dent disease in Japan with advanced chronic kidney disease
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Tetsuo Mori, Junko Takita, Takashi Sekine, Yoshihiko Hidaka, Ken Saida, Kenichi Koike, Shunsuke Noda, Hisashi Shimojo, Yuji Kamijo, Takashi Ehara, Kenichiro Miura, Takashi Igarashi, and Daisuke Matsuoka
- Subjects
Nephrology ,medicine.medical_specialty ,Pathology ,Pediatrics ,biology ,business.industry ,CLCN5 ,Renal function ,Dent Disease ,Case Report ,General Medicine ,medicine.disease ,Focal segmental glomerulosclerosis ,Tubulopathy ,Internal medicine ,biology.protein ,Medicine ,Nephrocalcinosis ,business ,Kidney disease - Abstract
Dent disease is an inherited tubulopathy caused by a mutation in the CLCN5 chloride channel gene. In cases of Dent disease in Japan (Japanese Dent, J-Dent), renal function is generally preserved and rarely progresses to advanced kidney dysfunction. However, the long-term prognosis of J-Dent remains unknown. We report the case of a 32-year-old man with J-Dent who developed advanced kidney dysfunction. Since the age of 3 years, he persistently exhibited proteinuria, and examination of a kidney biopsy specimen indicated focal segmental glomerulosclerosis (FSGS)-like lesions. Repeated corticosteroid treatments were found to be ineffective. After the age of 18 years, the patient was lost to follow-up and treatment was discontinued. The patient presented to our hospital again at the age of 32 years with advanced kidney dysfunction with low-molecular-weight proteinuria (LMWP), along with proximal tubular dysfunction and nephrocalcinosis. The patient’s 5-year-old nephew was also found to have LMWP from the age of 7 months. Therefore, Dent disease was suspected and genetic testing in the patient and his nephew revealed a CLCN5 mutation. Our case report suggests that J-Dent may cause advanced kidney dysfunction in adulthood, and, therefore, close collaboration between pediatricians and nephrologists is essential for the early identification of this complication. When male patients exhibit chronic kidney disease (CKD) of unknown etiology along with proximal tubular dysfunction and nephrocalcinosis, Dent disease should be considered. Investigations of undiagnosed adult J-Dent cases and further research on the natural history of J-Dent will help us better understand its clinical characteristics, prognosis, and effective treatment options.
- Published
- 2013
208. A computational model for the detection of object motion by moving observer using self-motion signals
- Author
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Takashi Nagano and Kenichiro Miura
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Retina ,Information Systems and Management ,Computer science ,business.industry ,Observer (special relativity) ,Object motion ,Computer Science Applications ,Theoretical Computer Science ,medicine.anatomical_structure ,Match moving ,Motion field ,Artificial Intelligence ,Control and Systems Engineering ,Motion estimation ,medicine ,Structure from motion ,Self motion ,Computer vision ,Artificial intelligence ,business ,Software - Abstract
Generally, image motion is induced all over the retina when an observer moves around. In spite of this, we can immediately detect objects moving in our surroundings. In this paper, a computational model is proposed to explain such detection using self-motion signals. First, we analyze the general characteristics of retinal image motion caused by both object motion and observer motion. Then a computational model is constructed in which true object motion is detected using signals of self-motion and depth values under the supposition that the surroundings are always stationary. It is suggested that the nervous system uses similar mechanisms.
- Published
- 2000
209. Effects of smooth pursuit eye movement on ocular responses to sudden background motion in humans
- Author
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Yasushi Kodaka, Aya J. Takemura, Kenji Kawano, Kazuyo Suehiro, Kenichiro Miura, and Yuka Inoue
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Adult ,Male ,Communication ,genetic structures ,business.industry ,General Neuroscience ,Motion Perception ,Eye movement ,Fixation, Ocular ,General Medicine ,Visual motion processing ,Middle Aged ,Pursuit, Smooth ,Smooth pursuit ,Reaction Time ,Humans ,Female ,Visual Pathways ,Psychology ,business ,Neuroscience - Abstract
We studied the effects of horizontal smooth pursuit on the ocular tracking responses to brief perturbations of a textured background in humans. When the subject was fixating a stationary spot, a brief perturbation (60°/s, 40 ms) of the background in any one of four directions (right, left, up, down) elicited a small tracking response. When the subject was pursuing a target moving against the stationary background, the same background perturbation elicited a larger response when in the same direction as the pursuit, but a smaller response when its direction was opposite to the pursuit; the response to vertical background perturbations was also enhanced during pursuit. When the subject was pursuing while the target and background were moving together, the same background perturbations elicited the larger responses regardless of their direction. These results indicate that the sensitivity to background motion is increased during smooth pursuit. However, when pursuit is executed against a stationary background – the usual situation in everyday life – the system is selectively insensitive to the reafferent visual input associated with pursuit, thereby reducing the potentially adverse effect of the background on pursuit performance.
- Published
- 1999
210. A Method Utilizing Motion Signals from a Camera for the Detection of Actual Moving Objects
- Author
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Takashi Nagano and Kenichiro Miura
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Image flow ,Computer science ,business.industry ,Computation ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Improved method ,Motion (physics) ,Computer Science Applications ,Image (mathematics) ,Match moving ,Camera auto-calibration ,Computer Science::Computer Vision and Pattern Recognition ,Component (UML) ,Media Technology ,Computer vision ,Artificial intelligence ,Electrical and Electronic Engineering ,business - Abstract
In this paper, we propose a method for the detection of actual moving objects in a moving image obtained by a moving camera. First, we construct a basic method for the detection of actual moving objects by utilizing motion signals of a camera. In this method, actual moving objects are detected based on the difference between the actual image flow observed and the predicted image flow computed by utilizing motion signals of a camera. The basic method has some requirements which are difficult to satisfy, such as exact computation of depth values in the surroundings. Therefore, we improve this method to perform the correct detection of actual moving objects without depth signals. In the improved method, the detection is performed based on whether the actual image flow is involved in a subregion of the image flow which is computed as that of stationary objects or not. In this method, the exact computaion of depth values in the surroundings and the computation of a speed component for the translational motion of a camera are not required.
- Published
- 1998
211. Relationship between sandstone composition in the Cretaceous Shimanto Supergroup, eastern Shikoku, and Cretaceous are volcanism
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Kenichiro Miura, Takao Iwata, Kazuo Kiminami, and Takuji Matsuura
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Paleontology ,General Engineering ,General Earth and Planetary Sciences ,Volcanism ,Supergroup ,Geology ,Cretaceous ,General Environmental Science - Published
- 1998
212. Japanese Dent disease has a wider clinical spectrum than Dent disease in Europe/USA: genetic and clinical studies of 86 unrelated patients with low-molecular-weight proteinuria
- Author
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Fusako Komoda, Kenichiro Miura, Takeshi Matsuyama, Takashi Igarashi, Junko Takita, Takashi Sekine, Mitsunobu Shimadzu, and Akira Ashida
- Subjects
Adult ,Male ,medicine.medical_specialty ,Pathology ,Adolescent ,DNA Mutational Analysis ,Rickets ,Dent Disease ,Disease ,Gastroenterology ,Young Adult ,Japan ,Chloride Channels ,Internal medicine ,medicine ,Humans ,Hypercalciuria ,Child ,Transplantation ,Dent's disease ,Proteinuria ,biology ,business.industry ,CLCN5 ,Incidence ,Infant ,DNA ,medicine.disease ,Phosphoric Monoester Hydrolases ,United States ,Europe ,Phenotype ,Nephrology ,Child, Preschool ,Mutation ,biology.protein ,Female ,Nephrocalcinosis ,medicine.symptom ,business ,Biomarkers - Abstract
Dent disease is an X-linked disorder characterized by low-molecular-weight (LMW) proteinuria, hypercalciuria, nephrocalcinosis, urolithiasis and renal dysfunction. Dent disease is caused by mutations in at least two genes, i.e. CLCN5 and OCRL1, and its genetic background and phenotypes are common among European countries and the USA. However, only few studies on Dent disease in Japan, which was originally called 'low-molecular-weight proteinuric disease', have been reported thus far. In this study, we analysed genetic background and clinical phenotype and laboratory data of 86 unrelated Japanese Dent disease patients. The results demonstrated that the genetic basis of Japanese Dent disease was nearly identical to those of Dent disease in other countries. Of 86 unrelated Japanese Dent patients, 61 possessed mutations in CLCN5 (Dent-1), of which 27 were novel mutations; 11 showed mutations in OCRL1 (Dent-2), six of which were novel, and the remaining 14 patients showed no mutations in CLCN5 or OCRL1 (Dent-NI). Despite the similarity in genetic background, hypercalciuria was detected in only 51%, rickets in 2% and nephrocalcinosis in 35%. Although the patients were relatively young, six patients (8%) showed apparent renal dysfunction. Japanese Dent disease has a wider clinical spectrum than Dent disease in Europe and the USA.
- Published
- 2013
213. Mutational analyses of the ATP6V1B1 and ATP6V0A4 genes in patients with primary distal renal tubular acidosis
- Author
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Kazuhiro Takahashi, Junko Takita, Takashi Sekine, Yutaka Harita, Takashi Igarashi, Masataka Hisano, Asako Tajima, Kenichiro Miura, Miki Murai, Myoung-ja Park, Yasuhide Hayashi, Masayuki Ishihara, and Kentaro Ohki
- Subjects
Adult ,Male ,Vacuolar Proton-Translocating ATPases ,Adolescent ,Nonsense mutation ,DNA Mutational Analysis ,Biology ,Compound heterozygosity ,medicine.disease_cause ,Real-Time Polymerase Chain Reaction ,Frameshift mutation ,Renal tubular acidosis ,Exon ,Young Adult ,Distal renal tubular acidosis ,medicine ,Humans ,Family ,Child ,Gene ,Genetics ,Transplantation ,Mutation ,Infant, Newborn ,Infant ,Acidosis, Renal Tubular ,Exons ,Middle Aged ,medicine.disease ,Prognosis ,Molecular biology ,Nephrology ,Child, Preschool ,Female ,Follow-Up Studies - Abstract
Background. Mutations in the ATP6V1B1 and the ATP6V0A4 genes cause primary autosomal-recessive distal renal tubular acidosis (dRTA). Large deletions of either gene in patients with dRTA have not been described. Methods. The ATP6V1B1 and ATP6V0A4 genes were directly sequenced in 11 Japanese patients with primary dRTA from nine unrelated kindreds. Large heterozygous deletions were analyzed by quantitative real-time polymerase chain reaction (PCR). The clinical features of the 11 patients were also investigated. Results. Novel mutations in the ATP6V1B1 gene were identified in two kindreds, including frameshift, in-frame insertion and nonsense mutations. Large deletions in the ATP6V0A4 gene were identified in two kindreds. Exon 15 of ATP6V0A4 was not amplified in one patient, with a long PCR confirming compound heterozygous deletions of 3.7and 6.9-kb nucleotides, including all of exon 15. Direct DNA sequencing revealed a heterozygous frameshift mutation in ATP6V0A4 in another patient, with quantitative real-time PCR indicating that all exons up to exon 8 were deleted in one allele. Clinical investigation showed that four of the six patients with available clinical data presented with hyperammonemia at onset. Conclusions. To our knowledge, these dRTA patients are the first to show large deletions involving one or more entire exons of the ATP6V0A4 gene. Quantitative PCR amplification may be useful in detecting heterozygous large deletions. These results expand the spectrum of mutations in the ATP6V0A4 and ATP6V1B1 genes associated with primary dRTA and provide insight into possible structure–function relationships.
- Published
- 2013
214. Contributions of retinal direction-selective ganglion cells to optokinetic responses in mice
- Author
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Kenichiro Miura, Fumiyuki Araki, Takahisa Furukawa, Kenji Kawano, and Yuko Sugita
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Retinal Ganglion Cells ,Retinal Bipolar Cells ,Visual perception ,Mice, 129 Strain ,genetic structures ,Mutant ,TRPM Cation Channels ,Biology ,Stimulus (physiology) ,Direction selective ,Receptors, Metabotropic Glutamate ,chemistry.chemical_compound ,Mice ,medicine ,Animals ,Nystagmus, Optokinetic ,Mice, Knockout ,General Neuroscience ,Eye movement ,Retinal ,Optokinetic reflex ,Ganglion ,Mice, Inbred C57BL ,medicine.anatomical_structure ,chemistry ,Neuroscience ,Photic Stimulation - Abstract
In the mouse retina, there are two distinct groups of direction-selective ganglion cells, ON and ON-OFF, that detect movement of visual images. To understand the roles of these cells in controlling eye movements, we studied the optokinetic responses (OKRs) of mutant mice with dysfunctional ON-bipolar cells that have a functional obstruction of transmission to ON direction-selective ganglion cells. Experiments were carried out to examine the initial and late phases of OKRs. The initial phase was examined by measurement of eye velocity using stimuli of sinusoidal grating patterns of various spatiotemporal frequencies that moved for 0.5 s. The mutant mice showed significant initial OKRs, although the range of spatiotemporal frequencies that elicited these OKRs was limited and the response magnitude was weaker than that in wild-type mice. To examine the late phase of the OKRs, the same visual patterns were moved for 30 s to induce alternating slow and quick eye movements (optokinetic nystagmus) and the slow-phase eye velocity was measured. Wild-type mice showed significant late OKRs with a stimulus in an appropriate range of spatiotemporal frequencies (0.0625-0.25 cycles/°, 0.75-3.0 Hz, 3-48°/s), but mutant mice did not show late OKRs in response to the same visual stimuli. The results suggest that two groups of direction-selective ganglion cells play different roles in OKRs: ON direction-selective ganglion cells contribute to both initial and late OKRs, whereas ON-OFF direction-selective ganglion cells contribute to OKRs only transiently.
- Published
- 2013
215. SIRPα interacts with nephrin at the podocyte slit diaphragm
- Author
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Yuko, Kajiho, Yutaka, Harita, Hidetake, Kurihara, Shigeru, Horita, Atsuko, Matsunaga, Haruko, Tsurumi, Shoichiro, Kanda, Noriko, Sugawara, Kenichiro, Miura, Takashi, Sekine, Seisuke, Hattori, Motoshi, Hattori, and Takashi, Igarashi
- Subjects
Nephrotic Syndrome ,Podocytes ,Kidney Glomerulus ,Membrane Proteins ,Antigens, Differentiation ,Rats ,Disease Models, Animal ,Proteinuria ,Mutation ,Animals ,Humans ,Tyrosine ,Phosphorylation ,Receptors, Immunologic ,Protein Binding - Abstract
The slit diaphragm (SD) is an intercellular junction between renal glomerular epithelial cells (podocytes) that is essential for permselectivity in glomerular ultrafiltration. The SD components, nephrin and Neph1, assemble a signaling complex in a tyrosine phosphorylation dependent manner, and regulate the unique actin cytoskeleton of podocytes. Mutations in the NPHS1 gene that encodes nephrin cause congenital nephrotic syndrome (CNS), which is characterized by the loss of the SD and massive proteinuria. Recently, we have identified the expression of the transmembrane glycoprotein signal regulatory protein α (SIRPα) at the SD. In the present study, we analyzed the expression of SIRPα in developing kidneys, in kidneys from CNS patients and in proteinuric rat models. The possibility that SIRPα interacts with known SD proteins was also investigated. SIRPα was concentrated at the SD junction during the maturation of intercellular junctions. In the glomeruli of CNS patients carrying mutations in NPHS1, where SD formation is disrupted, the expression of SIRPα as well as Neph1 and nephrin was significantly decreased, indicating that SIRPα is closely associated with the nephrin complex. Indeed, SIRPα formed hetero-oligomers with nephrin in cultured cells and in glomeruli. Furthermore, the cytoplasmic domain of SIRPα was highly phosphorylated in normal glomeruli, and its phosphorylation was dramatically decreased upon podocyte injury in vivo. Thus, SIRPα interacts with nephrin at the SD, and its phosphorylation is dynamically regulated in proteinuric states. Our data provide new molecular insights into the phosphorylation events triggered by podocyte injury.
- Published
- 2012
216. Facilitative integration of local motion signals in the peripheral visual field observed in monkey ocular following responses
- Author
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Kenichiro Miura, Kenji Kawano, and Yuki Aoki
- Subjects
Physics ,Communication ,genetic structures ,business.industry ,General Neuroscience ,media_common.quotation_subject ,Motion Perception ,Motion (geometry) ,Brain ,General Medicine ,STRIPS ,Macaca mulatta ,Visual motion ,Electric Stimulation ,Peripheral ,Visual field ,law.invention ,Optics ,law ,Animals ,Spatial frequency ,Eccentricity (behavior) ,business ,media_common - Abstract
To explore how local motion signals in the peripheral visual field are integrated, we recorded ocular following responses (OFRs) to moving vertical gratings extending across a wide horizontal width (1) of various vertical heights, (2) of a thin strip (4° height) at various vertical eccentricities, and (3) of two thin strips separated with various vertical distances (double-grating) in four monkeys. We found that the OFRs became larger and responsive more to lower spatial frequency than to higher as the vertical height of the motion stimuli increased up to 8° or 16°. This result is consistent with the incorporation of visual motion signals originating in the peripheral visual field; the OFRs to thin strips of drifting gratings were tuned for lower spatial frequency as the eccentricity increased. We also found that the OFRs to the double-gratings were quite similar to the sum of the responses to the single gratings in the initial period, but were significantly larger than the linear-sum in the final period. This result suggests that a non-linear mechanism, by which weak local motion signals are integrated into an effective ensemble, underlies the OFRs.
- Published
- 2012
217. Principal Fourier component of motion stimulus dominates the initial optokinetic response in mice
- Author
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Kenichiro Miura, Kenji Kawano, and Yuko Sugita
- Subjects
Male ,genetic structures ,Motion Perception ,Stimulus (physiology) ,symbols.namesake ,Mice ,Reaction Time ,Animals ,Nystagmus, Optokinetic ,Communication ,Monocular ,Fourier Analysis ,business.industry ,General Neuroscience ,Eye movement ,General Medicine ,Optokinetic reflex ,Mice, Inbred C57BL ,Fourier transform ,Cortical control ,symbols ,Missing fundamental ,Brainstem ,business ,Psychology ,Neuroscience ,Photic Stimulation - Abstract
Optokinetic responses (OKRs) are reflexive eye movements elicited by a moving visual pattern, and have been recognized in a variety of species. Several brainstem and cortical structures are known to be implicated in the generation of OKRs in primates, while the OKRs of afoveate mammals have been posited to be dominated by subcortical structures. To understand the subcortical mechanism underlying OKRs, the initial OKRs to horizontal quarter-wavelength steps applied to vertical grating patterns were studied in adult C57BL/6J mice under the monocular viewing conditions. The initial OKRs to sinusoidal gratings showed directional asymmetry with temporal-to-nasal predominance, a common characteristic of afoveate mammals that uses the subcortical structures to elicit OKRs. We then examined whether the OKRs of afoveate mammals are driven by the same visual features of the moving images as those in primates. The OKRs in mice were elicited by using the missing fundamental (mf) stimuli and its variants that had been used to understand the mechanism(s) underlying the cortical control of eye movements in primates. We obtained the results indicating that the OKRs of mice are driven by the principal Fourier component of moving visual image as in primates despite the differences in neural circuitries.
- Published
- 2011
218. Direction and speed tuning to visual motion in cortical areas MT and MSTd during smooth pursuit eye movements
- Author
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Naoko Inaba, Kenji Kawano, and Kenichiro Miura
- Subjects
Male ,Time Factors ,genetic structures ,Sensory Receptor Cells ,Physiology ,Computer science ,Stimulus (physiology) ,Smooth pursuit ,Retina ,chemistry.chemical_compound ,Motion ,medicine ,Animals ,Visual Cortex ,Communication ,business.industry ,General Neuroscience ,Eye movement ,Retinal ,Macaca mulatta ,Retinal image ,Visual motion ,Pursuit, Smooth ,Temporal Lobe ,medicine.anatomical_structure ,chemistry ,Models, Animal ,Visual Perception ,Neuron ,business ,Neuroscience ,Photic Stimulation - Abstract
When tracking a moving target in the natural world with pursuit eye movement, our visual system must compensate for the self-induced retinal slip of the visual features in the background to enable us to perceive their actual motion. We previously reported that the speed of the background stimulus in space is represented by dorsal medial superior temporal (MSTd) neurons in the monkey cortex, which compensate for retinal image motion resulting from eye movements when the direction of the pursuit and background motion are parallel to the preferred direction of each neuron. To further characterize the compensation observed in the MSTd responses to the background motion, we recorded single unit activities in cortical areas middle temporal (MT) and MSTd, and we selected neurons responsive to a large-field visual stimulus. We studied their responses to the large-field stimulus in the background while monkeys pursued a moving target and while fixated a stationary target. We investigated whether compensation for retinal image motion of the background depended on the speed of pursuit. We also asked whether the directional selectivity of each neuron in relation to the external world remained the same even during pursuit and whether compensation for retinal image motion occurred irrespective of the direction of the pursuit. We found that the majority of the MSTd neurons responded to the visual motion in space by compensating for the image motion on the retina resulting from the pursuit regardless of pursuit speed and direction, whereas most of the MT neurons responded in relation to the genuine retinal image motion.
- Published
- 2011
219. Morphological and functional analyses of two infants with obstructive renal dysplasia
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Riki Nishimura, Kenichiro Miura, Takashi Sekine, Takashi Igarashi, Michio Nagata, Yutaka Kanamori, Atsuhiro Yanagisawa, and Kiyohide Sakai
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Nephrology ,Male ,medicine.medical_specialty ,Pathology ,Physiology ,Megaureter ,Urinary system ,Urology ,Multicystic dysplastic kidney ,Kidney ,Kidney Tubules, Proximal ,Ureter ,Physiology (medical) ,Internal medicine ,medicine ,Humans ,Multicystic Dysplastic Kidney ,Hydronephrosis ,Ultrasonography ,business.industry ,Infant, Newborn ,Infant ,medicine.disease ,Renal dysplasia ,medicine.anatomical_structure ,Urogenital Abnormalities ,Female ,Urinary tract obstruction ,business ,Ureteral Obstruction - Abstract
Renal dysplasia associated with urinary tract obstruction comprises two distinct phenotypes, i.e., multicystic dysplastic kidney (MCDK) and obstructive renal dysplasia (ORD). MCDK is a common manifestation in infants with renal dysplasia, which is characterized by multiloculated thin-walled cysts with no functional parenchyma and an atretic ureter owing to pyelocalyceal occlusion early in fetal life. In contrast, ORD is an extremely rare condition which is caused by severe obstruction of the distal ureter or urethra. Here, we report two infants with ORD. Both patients manifested unilateral kidney enlargement with multiple cortical cysts, mild hydronephrosis, and marked dilatation of the ipsilateral ureter. Contralateral kidneys and urinary tracts revealed no apparent radiological abnormalities. Serial ultrasonographic studies of fetal and neonatal kidneys in both cases revealed that ureteral dilatation was evident at gestational week 16 and 27, respectively, and most of the cortical cysts disappeared within 1–3 months after birth. The functions of the affected kidneys were severely impaired but evident at the time of birth. These manifestations were consistent with a diagnosis of ORD, and were distinct from the features of MCDK. Our observation of fetal and infantile kidneys in these two cases provides us with a better understanding of the pathogenesis of ORD.
- Published
- 2010
220. Resolution of Henoch-Schönlein purpura nephritis after acquired IgA deficiency
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Tomonosuke Someya, Toshiro Fujita, Hiroshi Hataya, Kenichi Ishizawa, Michio Nagata, Junichi Hirahashi, Takashi Sekine, Kenichiro Miura, Mototsugu Tanaka, and George Seki
- Subjects
Nephrology ,medicine.medical_specialty ,IgA Vasculitis ,Biopsy ,Renal function ,Kidney ,Gastroenterology ,Young Adult ,hemic and lymphatic diseases ,Internal medicine ,medicine ,Parvovirus B19, Human ,Humans ,Kidney surgery ,Proteinuria ,Nephritis ,medicine.diagnostic_test ,business.industry ,IgA Deficiency ,Glomerulonephritis ,Glomerulonephritis, IGA ,medicine.disease ,Purpura ,Pediatrics, Perinatology and Child Health ,Immunology ,Female ,medicine.symptom ,business ,Immunosuppressive Agents - Abstract
We report a case of Henoch-Schonlein purpura nephritis (HSPN) with acquired IgA deficiency due to parvovirus B19 infection. The patient was diagnosed as having Henoch-Schonlein purpura (HSP) at 6 years old, and subsequently developed macrohematuria and massive proteinuria of 7.4 g/day with decreased creatinine clearance of 70.2 ml/min/1.73 m(2) and significantly elevated serum IgA level of 449 mg/dl. The first kidney biopsy yielded the diagnosis of severe HSPN. After the initiation of the immunosuppressive therapy, the patient was infected with parvovirus B19 and developed virus-associated hemophagocytic syndrome (VAHS). Thereafter, the serum level of IgA selectively decreased and remained undetectable until the present time. Repeated kidney biopsies performed over a period of 14 years revealed a remarkable histological improvement in association with stabilization of the patient's kidney function. Considering the severity of initial kidney injury, persistent acquired IgA deficiency was likely to add favorable effects to the immunosuppressive therapy in this patient with HSPN.
- Published
- 2010
221. Children's toxicology from bench to bed--Drug-induced renal injury (1): The toxic effects of ARB/ACEI on fetal kidney development
- Author
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Takashi Sekine, Takashi Igarashi, Kazuhiro Takahashi, and Kenichiro Miura
- Subjects
medicine.medical_specialty ,Urinary system ,Urology ,Kidney development ,Angiotensin-Converting Enzyme Inhibitors ,Toxicology ,Kidney ,Fetal Kidney ,Renin-Angiotensin System ,Mice ,Pregnancy ,Internal medicine ,Renin–angiotensin system ,Morphogenesis ,Medicine ,Animals ,Humans ,cardiovascular diseases ,Urinary Tract ,business.industry ,Nephrogenic diabetes insipidus ,medicine.disease ,Obstructive Nephropathy ,Endocrinology ,medicine.anatomical_structure ,Prenatal Exposure Delayed Effects ,Kidney Failure, Chronic ,Female ,business ,Angiotensin II Type 1 Receptor Blockers - Abstract
Development of fetal kidney is a finely programmed sequence, and is regulated by many important molecules. The perturbation of normal kidney development leads to congenital anomalies of kidney and urinary tract (CAKUT). CAKUT includes hypoplastic/dysplastic kidney, obstructive nephropathy and several other anomalies. CAKUT is of clinically importance, since it could lead to end stage renal failure when its anomaly grade is severe. So far, several causative genes responsible for development of CAKUT have been identified, including genes encoding molecules related to the renin-angiotensin-aldosterone system, RAS system. In humans, maternal administration of agents with inhibitory effects on the RAS system, such as angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin type 1 receptor blockers (ARBs), have been reported to cause severe renal malformation, designated as ACEI/ARB fetopathy. In this paper, we overview the development of fetal kidney and address the effects of ACEIs/ARBs on fetal kidney.
- Published
- 2009
222. Initiation of the optokinetic response (OKR) in mice
- Author
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Yoshiro Wada, Naoki Shimizu, Hiromitsu Tabata, Kenichiro Miura, and Kenji Kawano
- Subjects
Visual perception ,genetic structures ,Photic Stimulation ,Models, Neurological ,Motion Perception ,Nystagmus ,Stimulus (physiology) ,Tonic (physiology) ,Contrast Sensitivity ,Mice ,Optics ,Motor system ,medicine ,Reaction Time ,Animals ,Nystagmus, Optokinetic ,Chemistry ,business.industry ,Eye movement ,Optokinetic reflex ,Sensory Systems ,Pursuit, Smooth ,Mice, Inbred C57BL ,Ophthalmology ,medicine.symptom ,business ,Neuroscience - Abstract
To study the initial part of the mouse optokinetic response, OKR (approximately 500 ms from the onset of visual stimulus motion), we recorded the ocular response to a vertical sinusoidal grating moving at a constant velocity. We found that the magnitude of the response monotonically increased as the stimulus contrast increased. The response showed a narrow band-pass property for the spatiotemporal frequency, with the largest sustained response observed at 0.125 cycle/deg and 1.5 Hz. We also found that temporal frequencies higher than 1.5 Hz elicited transient increase in the eye velocity, but weak or no sustained eye movements. Thus the initial OKR in mice is characterized by the spatiotemporal frequency of the visual stimuli. Our results suggest that the initial OKR contains two components: a transient that diminishes within approximately 200 ms, and a tonic that is maintained for more than 400 ms, and that the initial part of the OKR in mice is an appropriate measurement parameter for studies of the visual and motor systems, like ocular following response (OFR) in primates.
- Published
- 2009
223. Hypothetical membrane mechanisms in essential tremor
- Author
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David S. Zee, Stefano Ramat, Lance M. Optican, Kenichiro Miura, Aasef G. Shaikh, and Robert M Tripp
- Subjects
medicine.medical_specialty ,Essential Tremor ,Models, Neurological ,lcsh:Medicine ,Biology ,General Biochemistry, Genetics and Molecular Biology ,Membrane Potentials ,Cell membrane ,Internal medicine ,Reciprocal innervation ,medicine ,Biological neural network ,Humans ,Computer Simulation ,Medicine(all) ,Motor Neurons ,Membrane potential ,Essential tremor ,Biochemistry, Genetics and Molecular Biology(all) ,Research ,lcsh:R ,Cell Membrane ,General Medicine ,Hyperpolarization (biology) ,Neurophysiology ,medicine.disease ,Phenotype ,medicine.anatomical_structure ,Endocrinology ,Neuron ,Ion Channel Gating ,Neuroscience - Abstract
Background Essential tremor (ET) is the most common movement disorder and its pathophysiology is unknown. We hypothesize that increased membrane excitability in motor circuits has a key role in the pathogenesis of ET. Specifically, we propose that neural circuits controlling ballistic movements are inherently unstable due to their underlying reciprocal innervation. Such instability is enhanced by increased neural membrane excitability and the circuit begins to oscillate. These oscillations manifest as tremor. Methods Postural limb tremor was recorded in 22 ET patients and then the phenotype was simulated with a conductance-based neuromimetic model of ballistic movements. The model neuron was Hodgkin-Huxley type with added hyperpolarization activated cation current (Ih), low threshold calcium current (IT), and GABA and glycine mediated chloride currents. The neurons also featured the neurophysiological property of rebound excitation after release from sustained inhibition (post-inhibitory rebound). The model featured a reciprocally innervated circuit of neurons that project to agonist and antagonist muscle pairs. Results Neural excitability was modulated by changing Ih and/or IT. Increasing Ih and/or IT further depolarized the membrane and thus increased excitability. The characteristics of the tremor from all ET patients were simulated when Ih was increased to ~10× the range of physiological values. In contrast, increasing other membrane conductances, while keeping Ih at a physiological value, did not simulate the tremor. Increases in Ih and IT determined the frequency and amplitude of the simulated oscillations. Conclusion These simulations support the hypothesis that increased membrane excitability in potentially unstable, reciprocally innervated circuits can produce oscillations that resemble ET. Neural excitability could be increased in a number of ways. In this study membrane excitability was increased by up-regulating Ih and IT. This approach suggests new experimental and clinical ways to understand and treat common tremor disorders.
- Published
- 2008
224. The initial disparity vergence elicited with single and dual grating stimuli in monkeys: evidence for disparity energy sensing and nonlinear interactions
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Kenichiro Miura, Kenji Kawano, Kiyoto Matsuura, Naoko Inaba, Frederick A. Miles, and Yuko Sugita
- Subjects
Vision Disparity ,genetic structures ,Physiology ,Vergence eye movements ,Motion Perception ,Normal Distribution ,Vergence ,Grating ,Psychophysics ,Reaction Time ,Animals ,Humans ,Short latency ,Computer vision ,Physics ,Communication ,Vision, Binocular ,business.industry ,General Neuroscience ,Articles ,DUAL (cognitive architecture) ,Convergence, Ocular ,Macaca mulatta ,Nonlinear system ,Nonlinear Dynamics ,Energy sensing ,Data Interpretation, Statistical ,Artificial intelligence ,business ,Photic Stimulation - Abstract
We recorded the initial vertical vergence eye movements elicited in monkeys at short latency (∼70 ms) when the two eyes see one-dimensional (1D) horizontal grating patterns that are identical except for a phase difference (disparity) of one-quarter wavelength. With gratings composed of single sine waves, responses were always compensatory, showing Gaussian dependence on log spatial frequency (on average: peak = 0.75 cycles/deg; SD = 0.74; r2 = 0.980) and monotonic dependence on log contrast with a gradual saturation well described by the Naka-Rushton equation (on average: n = 0.89; C50 = 4.1%; r2 = 0.978). With gratings composed of two sine waves whose spatial frequencies were in the ratio 3:5 and whose disparities were of opposite sign (the 3f5f stimulus), responses were determined by the disparities and contrasts of the two sine-wave components rather than the disparity of the features, consistent with early spatial filtering of the monocular inputs before their binocular combination and mediation by detectors sensitive to disparity energy. In addition, responses to the 3f5f stimulus showed a nonlinear dependence on the relative contrasts of the two sine waves. Thus on average, when the contrast of one sine wave was 2.3 times greater than that of the other, the one with the lower contrast was largely ineffective as though suppressed, and responses were determined almost entirely by the sine wave of higher contrast: Winner-Take-All. These findings are very similar to those published previously on the vertical vergence responses of humans, indicating that the monkey provides a good animal model for studying these disparity vergence responses.
- Published
- 2008
225. Clinical features and mutational survey of NPHS2 (podocin) in Japanese children with focal segmental glomerulosclerosis who underwent renal transplantation
- Author
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Yuko Akioka, Daisuke Ogino, Hyogo Nakakura, Akiko Kitamura, Takeki Furue, Kenichiro Miura, Hiroko Chikamoto, Kazuhiro Takahashi, Takashi Sakano, Hiroyasu Tsukaguchi, Akira Ashida, Motoshi Hattori, Masataka Hisano, and Tae Oomori
- Subjects
Nephrology ,Male ,medicine.medical_specialty ,Pathology ,DNA Mutational Analysis ,Consanguinity ,urologic and male genital diseases ,Gastroenterology ,Pathogenesis ,Primary FSGS ,Focal segmental glomerulosclerosis ,Japan ,Recurrence ,Internal medicine ,medicine ,Humans ,Family history ,Child ,Transplantation ,Alanine ,Polymorphism, Genetic ,biology ,business.industry ,Glomerulosclerosis, Focal Segmental ,Intracellular Signaling Peptides and Proteins ,Membrane Proteins ,medicine.disease ,Kidney Transplantation ,female genital diseases and pregnancy complications ,Child, Preschool ,Pediatrics, Perinatology and Child Health ,Mutation ,Podocin ,biology.protein ,Female ,business ,Immunosuppressive Agents - Abstract
Recurrent FSGS is a major challenge in the field of nephrology. To clarify the role of NPHS2 defects in the pathogenesis of FSGS recurrence, we sequenced all eight exons of NPHS2 in 11 Japanese pediatric FSGS patients with or without post-transplant recurrence. All patients had biopsy-proven primary FSGS, had no family history of renal diseases or consanguinity, were steroid-resistant, and received living-related renal transplantation. The mean age at onset was 5.0 +/- 3.1 yr and mean age at renal transplantation was 10.4 +/- 4.1 yr. Mutational analysis of NPHS2 was performed using polymerase chain reaction and direct sequencing. We found a synonymous T/C polymorphism at alanine 318 (GCC to GCT) in seven of 11 patients but no other causative NPHS2 mutations. FSGS recurred immediately after transplant in seven patients, while the remaining four patients had no recurrence for 3.2-5.8 yr. There were no differences between recurrent and non-recurrent patients in the onset age and the interval from onset to ESRD. In conclusion, we detected no causative NPHS2 mutations in Japanese pediatric FSGS patients with or without post-transplant recurrence. Further studies on the involvement of other genes are required to better understand recurrent FSGS.
- Published
- 2008
226. Trial-by-trial updating of the gain in preparation for smooth pursuit eye movement based on past experience in humans
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Hiromitsu Tabata, Kenichiro Miura, and Kenji Kawano
- Subjects
Adult ,Male ,medicine.medical_specialty ,genetic structures ,Physiology ,General Neuroscience ,Fixation, Ocular ,Middle Aged ,Adaptation, Physiological ,Smooth pursuit ,Pursuit, Smooth ,Developmental psychology ,Physical medicine and rehabilitation ,Memory, Short-Term ,Fixation (visual) ,medicine ,Reaction Time ,Visual Perception ,Response Amplitude ,Humans ,Female ,Psychology ,Photic Stimulation - Abstract
To understand how the CNS uses past experiences to generate movements that accommodate minute-by-minute environmental changes, we studied the trial-by-trial updating of the gain for initiating smooth pursuit eye movements and how this relates to the history of previous trials. Ocular responses in humans elicited by a small perturbing motion presented 300 ms after appearance of a target were used as a measure of the gain of visuomotor transmission. After the perturbation, the target was either moved horizontally (pursuit trial) or remained in a stationary position (fixation trial). The trial sequence randomly included pursuit and fixation. The amplitude of the response to the perturbation was modulated in a trial-by-trial manner based on the immediately preceding trial, with preceding fixation and pursuit trials decreasing and increasing the gain, respectively. The effect of the previous trial was larger with shorter intertrial intervals, but did not diminish for at least 2,000 ms. A time-series analysis showed that the response amplitude was significantly correlated with the past few trials, with dynamics that could be approximated by a first-order linear system. The results suggest that the CNS integrates recent experiences to set the gain in preparation for upcoming tracking movements in a changing environment.
- Published
- 2007
227. Saliency-guided eye movement during free-viewing in schizophrenic patients
- Author
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Ryota Hashimoto, Masaki Fukunaga, Tadashi Isa, Kenichiro Miura, Michiko Fujimoto, Yuka Yasuda, Masatoshi Takeda, Kazutaka Ohi, Hidenaga Yamamori, and Masatoshi Yoshida
- Subjects
Ophthalmology ,business.industry ,Eye movement ,Computer vision ,Artificial intelligence ,business ,Psychology ,Sensory Systems - Published
- 2015
228. The effects of preceding moving stimuli on the initial part of smooth pursuit eye movement
- Author
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Kenichiro Miura, Yasuo Hisa, Kenji Kawano, Hiromitsu Tabata, and Masakatsu Taki
- Subjects
Adult ,Male ,medicine.medical_specialty ,Visual perception ,genetic structures ,Motion Perception ,Crt monitor ,Audiology ,Stimulus (physiology) ,Smooth pursuit ,Optics ,Conditioning, Psychological ,medicine ,Humans ,Habituation, Psychophysiologic ,business.industry ,General Neuroscience ,Eye movement ,Middle Aged ,Adaptation, Physiological ,Pursuit, Smooth ,Prolonged exposure ,Middle temporal area ,Conditioning ,Female ,business ,Psychology ,Photic Stimulation - Abstract
We examined whether there are any adaptive effects on the pursuit initiation after a prolonged exposure to moving visual stimuli. The eye movements of six human subjects were recorded with the scleral search-coil technique or a Dual Purkinje Image Eye-tracker system. A random-dot image appeared on a CRT monitor and moved coherently in one direction (rightward or leftward) at 10 deg/s for 4 s, while the subject fixated on a stationary target (conditioning stimulus). The screen was blanked for 0.2 s, and then the target stepped to the right or left of the center and moved 10 deg/s leftward or rightward. We measured change in the eye position over the open-loop period of the pursuit initiation. When the pursuit target moved in the same direction as the preceding visual stimulus, a significant reduction in the initial tracking responses (55.9% decrease on average) was found. We then studied in detail the properties of the motion adaptation in pursuit initiation by varying the visual conditions systematically and obtained the following findings. When the subjects tracked the target that moved at 10 deg/s, the pursuit initiation was affected not only by the conditioning stimulus of the same speed as the target, but also by those of different speeds. Further, the conditioning stimulus moving at 10 deg/s affected the pursuit initiation not only when the target moved with the same speed but also when it moved at different speeds (more remarkable for slower speeds). The effect of conditioning stimuli on the pursuit initiation was larger when the duration of the conditioning period was longer. The effect of conditioning stimuli decayed as the duration of the blank period became longer. The findings from the present study are consistent with the properties of neurons in the middle temporal area of monkeys.
- Published
- 2005
229. Ocular tracking of moving targets: effects of perturbing the background
- Author
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Kenichiro Miura, Yasushi Kodaka, Aya Takemura, Kenji Kawano, and Kazuyo Suehiro
- Subjects
Communication ,genetic structures ,Eye Movements ,Physiology ,Computer science ,business.industry ,General Neuroscience ,Track (disk drive) ,Motion Perception ,Eye movement ,Fixation, Ocular ,Tracking (particle physics) ,Smooth pursuit ,Motion (physics) ,Conditioning, Psychological ,Animals ,Macaca ,Computer vision ,Artificial intelligence ,business ,Photic Stimulation - Abstract
Primates are able to track a moving target with their eyes, even when the target is seen against a stationary textured background. In this situation, the tracking eye movement induces motion of the background images on the retina (reafference) that competes with the motion of the target's retinal image, potentially disrupting the tracking of the target. Previous work on humans reported that brief perturbations of the background in the opposite direction to pursuit were much less disruptive than perturbations in the same direction as pursuit. Furthermore, if the background moved together with the pursuit target—so as to effectively eliminate the reafference—then the effects of a subsequent background perturbation showed less dependence on direction. This suggested that the direction selectivity to background perturbations during pursuit against a stationary background was due, at least in part, to the prior motion of the background secondary to the pursuit. We now report similar findings in monkeys, and in addition, have investigated the effect of moving the background while the animal was fixating a stationary target. In this situation, the ocular tracking responses to subsequent brief perturbations of the moving background were weaker when the perturbations were in the same direction as the prior background motion than when in the opposite direction. This suggests that the selective insensitivity to the reafferent visual input associated with pursuit across a stationary background is, at least in part, independent of pursuit per se and attributable to a progressive reduction in the sensitivity to sustained background motion.
- Published
- 2004
230. Activities of MT/MST neurons during ocular following responses to moving grating patterns composed of two sinusoids
- Author
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Kenji Kawano, Kenichiro Miura, Yuki Aoki, and Naoko Inaba
- Subjects
Physics ,Optics ,business.industry ,General Neuroscience ,General Medicine ,Grating ,business - Published
- 2010
231. The ROC analysis reveals different motion sensitivity of neurons in area MT/MSTd during smooth pursuit
- Author
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Naoko Inaba, Kenichiro Miura, and Kenji Kawano
- Subjects
Physics ,business.industry ,General Neuroscience ,Pattern recognition ,General Medicine ,Artificial intelligence ,Sensitivity (control systems) ,business ,Motion (physics) ,Smooth pursuit - Published
- 2011
232. Intra- and inter-visual area differences in optimal spatial frequency: A human fMRI study
- Author
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Kenichiro Miura, Hidenao Fukuyama, Kenji Kawano, Nobukatsu Sawamoto, Tetsuya Yamamoto, and Hiroki Yamamoto
- Subjects
Computer science ,General Neuroscience ,General Medicine ,Spatial frequency ,Cartography - Published
- 2011
233. Attentional effects underlying the improved visuomotor processing in tracking a moving visual stimulus
- Author
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Kenji Kawano, Kenichiro Miura, and Yugo Kobayashi
- Subjects
General Neuroscience ,General Medicine ,Stimulus (physiology) ,Psychology ,Cognitive psychology - Published
- 2011
234. The temporal property difference and the way of interactions between monocular and binocular motion mechanisms
- Author
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Hiromitsu Tabata, Kenichiro Miura, Kenji Kawano, and Ryusuke Hayashi
- Subjects
Ophthalmology ,Monocular ,Computer science ,business.industry ,Property (programming) ,Computer vision ,Artificial intelligence ,business ,Sensory Systems ,Motion (physics) - Published
- 2010
235. Non-linear integration of local motion signals underlying ocular following responses in monkeys
- Author
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Yuki Aoki, Kenji Kawano, and Kenichiro Miura
- Subjects
Physics ,Nonlinear system ,business.industry ,General Neuroscience ,Computer vision ,General Medicine ,Artificial intelligence ,business ,Motion (physics) - Published
- 2010
236. Visual Motion Processing To Elicit Optokinetic Responses In Mice
- Author
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Naoki Shimizu, Yuko Sugita, Kenichiro Miura, and Kenji Kawano
- Subjects
General Neuroscience ,General Medicine ,Optokinetic reflex ,Visual motion processing ,Psychology ,Neuroscience - Published
- 2010
237. Contribution of color signals to ocular following responses
- Author
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Kiyoto Matsuura, Kenji Kawano, and Kenichiro Miura
- Subjects
General Neuroscience ,General Medicine - Published
- 2009
238. Mechanism of visual motion detection in the MST area of monkey cortex
- Author
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Kenichiro Miura, Naoko Inaba, and Kenji Kawano
- Subjects
Physics ,medicine.anatomical_structure ,Mechanism (biology) ,General Neuroscience ,Cortex (anatomy) ,medicine ,General Medicine ,Motion perception ,Visual motion detection ,Neuroscience - Published
- 2009
239. Difference in perceptual and oculomotor responses revealed by apparent motion stimuli presented with an interstimulus interval.
- Author
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Shizuka Nohara, Kenji Kawano, and Kenichiro Miura
- Subjects
PERCEPTUAL learning ,EYE movements ,INTERSTIMULUS interval ,WAVELENGTHS ,VISUAL perception - Abstract
To understand the mechanisms underlying visual motion analyses for perceptual and oculomotor responses and their similarities/differences, we analyzed eye movement responses to two-frame animations of dual-grating 3f5f stimuli while subjects performed direction discrimination tasks. The 3f5f stimulus was composed of two sinusoids with a spatial frequency ratio of 3:5 (3f and 5f), creating a pattern with fundamental frequency f. When this stimulus was shifted by 1/4 of the wavelength, the two components shifted 1/4 of their wavelengths and had opposite directions: the 5f forward and the 3f backward. By presenting the 3f5f stimulus with various interstimulus intervals (ISIs), two visual-motion-analysis mechanisms, low-level energy-based and high-level feature-based, could be effectively distinguished. This is because response direction depends on the relative contrast between the components when the energy-based mechanism operates, but not when the feature-based mechanism works. We found that when the 3f5f stimuli were presented with shorter ISIs (>100 ms), and 3f component had higher contrast, both perceptual and ocular responses were in the direction of the pattern shift, whereas the responses were reversed when the 5f had higher contrast, suggesting operation of the energy-based mechanism. On the other hand, the ocular responses were almost negligible with longer ISIs (>100 ms), whereas perceived directions were biased toward the direction of pattern shift. These results suggest that the energy-based mechanism is dominant in oculomotor responses throughout ISIs; however, there is a transition from energy-based to feature-tracking mechanisms when we perceive visual motion. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
240. Ocular following responses elicited by binocular first-order motion in primates
- Author
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Ryusuke Hayashi, Kenji Kawano, Kenichiro Miura, and Hiromitsu Tabata
- Subjects
Physics ,General Neuroscience ,General Medicine ,First order ,Neuroscience ,Motion (physics) - Published
- 2007
241. The effect of a symbolic cue on human smooth pursuit initiation
- Author
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Hiromitsu Tabata, Kenichiro Miura, Kenji Kawano, and Yuki Aoki
- Subjects
General Neuroscience ,General Medicine ,Psychology ,Neuroscience ,Smooth pursuit - Published
- 2007
242. Difference in Visual Motion Representation between Cortical Areas MT and MST during Ocular Following Responses.
- Author
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Kenichiro Miura, Naoko Inaba, Yuki Aoki, and Kenji Kawano
- Subjects
- *
CEREBRAL cortex , *TEMPORAL lobe , *CELL nuclei , *SPATIOTEMPORAL processes , *AVERSIVE stimuli , *VESTIBULO-ocular reflex - Abstract
The middle temporal (MT) and medial superior temporal (MST) areas are successive stations of the visual motion-processing stream and project in parallel to the pontine nucleus, which is closely associated with rapid stabilization of gaze. We recorded the neural activities of MTand MST neurons of monkeys during short-latency ocular following responses (OFRs) elicited by large-field sinusoidal gratings with different spatial frequencies drifting at different temporal frequencies, and examined the dependence on spatiotemporal frequency. The results indicate that most MT/MST neurons were tuned almost separately for spatial and temporal frequencies of motion stimuli. The difference between MT and MST neurons was particularly striking for the optimal spatial frequency (higher for MT and lower for MST). The spatiotemporal frequency dependence of the OFRs could be reproduced by a weighted sum of the population activities of theMTand MSTneurons. We conclude thatMTandMSTneurons work as spatiotemporal frequency sensors that extract motions of finer and coarser visual features and that both areas contribute to generation of OFRs. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
243. 2702 Estimation of local image velocity vectors by using a sequence of local motion signals
- Author
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Takashi Nagano, Kenichiro Miura, and Wakako Urushihara
- Subjects
Computer science ,business.industry ,General Neuroscience ,Motion estimation ,Motion (geometry) ,Computer vision ,General Medicine ,Artificial intelligence ,business ,Image (mathematics) ,Sequence (medicine) - Published
- 1997
244. Membrane channel properties of premotor excitatory burst neurons may underlie saccade slowing after lesions of omnipause neurons.
- Author
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Kenichiro Miura and Lance Optican
- Abstract
Chemical lesions of the brain stem region containing glycinergic omnipause neurons (OPNs) cause saccade slowing with no change in latency. To explore the mechanisms responsible for this deficit, simulation studies were performed with a conductance-based model of premotor excitatory burst neurons (EBNs) that incorporated multiple membrane channels, including the T-type calcium channel. The peak speed of a normal saccade was determined by the T- and NMDA currents in EBNs after the OPNs shut off. After OPN lesions, the model made slow saccades, because the EBN activity was lower than normal due to a reduced T-current (caused by the loss of hyperpolarization), and a reduced NMDA current (caused by a reduced glycine concentration around the receptors). Thus, we propose that two biophysical mechanisms are responsible for saccade slowing after OPN lesions: reduced T-current and reduced NMDA current, both of which are caused by the loss of glycine from OPNs. [ABSTRACT FROM AUTHOR]
- Published
- 2006
245. Tenotomy and congenital nystagmus: a null result is not a failure, for 'It is not the answer that enlightens, but the question'
- Author
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Edmond J. FitzGibbon, Lance M. Optican, and Kenichiro Miura
- Subjects
medicine.medical_specialty ,Ophthalmology ,Null result ,business.industry ,medicine.medical_treatment ,Tenotomy ,Medicine ,business ,Congenital nystagmus ,Sensory Systems ,Surgery - Full Text
- View/download PDF
246. Effects of tenotomy surgery on congenital nystagmus waveforms in adult patients. Part I. Wavelet spectral analysis
- Author
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Kenichiro Miura, Edmond J. FitzGibbon, Richard W. Hertle, and Lance M. Optican
- Subjects
Adult ,medicine.medical_specialty ,Visual acuity ,genetic structures ,medicine.medical_treatment ,Eye disease ,Tenotomy ,Electromyography ,Nystagmus ,Wavelet analysis ,medicine ,Humans ,Congenital nystagmus ,medicine.diagnostic_test ,Eye movement ,Signal Processing, Computer-Assisted ,Electrooculography ,Middle Aged ,medicine.disease ,Sensory Systems ,eye diseases ,Surgery ,Oculomotor disorder ,Ophthalmology ,Oculomotor Muscle ,Oculomotor Muscles ,sense organs ,medicine.symptom ,Psychology ,Nystagmus, Congenital ,Human - Abstract
Congenital nystagmus (CN) is an aperiodic oscillatory eye movement disorder. Horizontal rectus tenotomy with simple re-attachment has been proposed as a therapy for CN. This therapy might affect vision and/or eye movements. Another paper deals with improvements in visual acuity. This and the companion paper examine changes in eye movements. In this study, we examined the effect of tenotomy on nystagmus waveforms using wavelet spectral analysis. No common effect was found across the patients on the wavelet spectra of the CN beat, suggesting that tenotomy surgery has no effect, or only a quite small effect, on the waveform structure of CN.
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247. A new familial disease of saccadic oscillations and limb tremor provides clues to mechanisms of common tremor disorders.
- Author
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Aasef G. Shaikh, Kenichiro Miura, Lance M. Optican, Stefano Ramat, R. John Leigh, and David S. Zee
- Subjects
- *
FAMILIAL diseases , *TREMOR , *MOVEMENT disorders , *SACCADIC eye movements , *PHENOTYPES , *NEUROPHYSIOLOGY - Abstract
Tremor disorders pose fundamental questions about disease mechanisms, and challenges to successful neurotherapeutics: What causes motor circuits to oscillate in disorders in which the central nervous system otherwise seems normal? How does inheritance ‘determine’ the clinical phenotype in familial tremor disorders? Here, we address these questions. Analogies between the neural circuits controlling rapid eye movements (saccades) and those controlling limb movements allow us to translate the interpretations from the saccadic systems to the limb movement system. Moreover, the relatively well understood neurophysiology of the ocular motor system offers a unique opportunity to test specific hypotheses about normal and abnormal motor control of both eye and limb movements. We describe a new familial disorder—‘micro-saccadic oscillations and limb tremor (μSOLT)’—in a mother and daughter who had tiny saccadic oscillations of the eyes and tremor of the hands. This unique oscillatory movement disorder resembles other common tremor disorders (such as essential tremor) that occur in patients who have an otherwise normally functioning central nervous system. We hypothesize that μSOLT is caused by an inherited abnormality that results in abnormal membrane properties causing reduced external inhibition in the premotor neurons that generate the high-frequency discharge (burst) for saccades and for ballistic limb movements. To test this hypothesis, we recorded hand tremor and eye movements in two patients with μSOLT and particularly during natural circumstances when inhibition of the premotor saccadic burst neurons is removed (e.g. eye closure). We then simulated a conductance-based model for the premotor commands which included excitatory and reciprocally inhibitory burst neurons. The structure of this physiologically realistic model was based upon known cell types and anatomical connections in the brainstem (for saccades) and the thalamus (for limb movements). The physiological phenomenon of post-inhibitory rebound in premotor burst neurons makes the circuit inherently unstable and prone to oscillate unless prevented by external inhibition. Indeed, with simulated reduction of external inhibition (in this case glycinergic), saccadic oscillations and limb tremor were reproduced. Our results suggest that a single-inherited deficit can alter membrane properties, which impairs inhibition in an inherently unstable neural circuit causing the eye and limb oscillations in μSOLT. This concept has broad implications for understanding the mechanism and designing rationale pharmacotherapy for abnormal oscillations and may be applicable to other common disorders in which there are no structural abnormalities in the brain such as essential tremor. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
248. Rituximab for childhood-onset, complicated, frequently relapsing nephrotic syndrome or steroid-dependent nephrotic syndrome: a multicentre, double-blind, randomised, placebo-controlled trial.
- Author
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Kazumoto lijima, Mayumi Sako, Kandai Nozu, Rintaro Mori, Nao Tuchida, Koichi Kamei, Kenichiro Miura, Kunihiko Aya, Koichi Nakanishi, Yoshiyuki Ohtomo, Shori Takahashi, Ryojiro Tanaka, Hiroshi Kaito, Hidefumi Nakamura, Kenji Ishikura, Shuichi Ito, and Yasuo Ohashi
- Subjects
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RITUXIMAB , *NEPHROTIC syndrome in children , *PEDIATRIC nephrology , *DRUG efficacy , *MEDICAL screening , *THERAPEUTICS - Abstract
Background Rituximab could be an effective treatment for childhood-onset, complicated, frequently relapsing nephrotic syndrome (FRNS) and steroid-dependent nephrotic syndrome (SDNS). We investigated the efficacy and safety of rituximab in patients with high disease activity. Methods We did a multicentre, double-blind, randomised, placebo-controlled trial at nine centres in Japan. We screened patients aged 2 years or older experiencing a relapse of FRNS or SDNS, which had originally been diagnosed as nephrotic syndrome when aged 1-18 years. Patients with complicated FRNS or SDNS who met all other criteria were eligible for inclusion after remission of the relapse at screening. We used a computer-generated sequence to randomly assign patients (1:1) to receive rituximab (375 mg/m2) or placebo once weekly for 4 weeks, with age, institution, treatment history, and the intervals between the previous three relapses as adjustment factors. Patients, guardians, caregivers, physicians, and individuals assessing outcomes were masked to assignments. All patients received standard steroid treatment for the relapse at screening and stopped taking immunosuppressive agents by 169 days after randomisation. Patients were followed up for 1 year. The primary endpoint was the relapse-free period. Safety endpoints were frequency and severity of adverse events. Patients who received their assigned intervention were included in analyses. This trial is registered with the University Hospital Medical Information Network clinical trials registry, number UMIN000001405. Findings Patients were centrally registered between Nov 13, 2008, and May 19, 2010. Of 52 patients who underwent randomisation, 48 received the assigned intervention (24 were given rituximab and 24 placebo). The median relapse-free period was significantly longer in the rituximab group (267 days, 95% Cl 223-374) than in the placebo group (101 days, 70-155; hazard ratio: 0 • 27, 0 • 14—0 • 53; p<0• 0001). Ten patients (42%) in the rituximab group and six (25%) in the placebo group had at least one serious adverse event (p=0 • 36). Interpretation Rituximab is an effective and safe treatment for childhood-onset, complicated FRNS and SDNS. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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