Publications by authors named "Masataka Nishimura"

Article Synopsis
  • - This study examined how oral ferric citrate hydrate (FCH) affects iron absorption in hemodialysis patients and looked at the role of hepcidin-25, a hormone that regulates iron metabolism, in this process.
  • - Over six months, 268 participants were treated with FCH, and researchers tracked changes in serum iron levels to assess absorption, finding that lower hepcidin-25 levels correlated with better iron absorption.
  • - Results indicated that as erythropoiesis (red blood cell production) was limited, patients experienced higher hepcidin-25 levels, leading to lower iron absorption from the intestine despite ongoing treatment with FCH.
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Spectrotemporal integration is a key function of our auditory system for discriminating spectrotemporally complex sounds, such as words. Response latency in the auditory cortex is known to change with the millisecond time-scale depending on acoustic parameters, such as sound frequency and intensity. The functional significance of the millisecond-range latency difference in the integration remains unclear.

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The core region of the rodent auditory cortex has two subfields: the primary auditory area (A1) and the anterior auditory field (AAF). Although the postnatal development of A1 has been studied in several mammalian species, few studies have been conducted on the postnatal development of AAF. Using a voltage-sensitive-dye-based imaging method, we examined and compared the postnatal development of AAF and A1 in mice from postnatal day 11 (P11) to P40.

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Temporal precision is a determinant of performance in various motor activities. Although the accuracy and precision of timing in activities have been previously measured and quantified, temporal dynamics with flexible precision have not been considered. Here, we examined the temporal dynamics in timed motor activities (timed actions) using a guinea pig model in a behavioural task requiring an animal to control action timing to obtain a water reward.

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Background: Rectal endometriosis is a rare disease. A definitive diagnosis prior to surgery is often difficult. We encountered a patient with rectal sub-obstructive endometriosis that was treated by robot-assisted laparoscopic low anterior resection.

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Background: Juvenile polyposis is an autosomal dominant inherited disease characterized by the development of numerous hamartomatous and nonneoplastic polyps of the gastrointestinal tract. Juvenile polyposis has also recently been reported as a predisposition for gastrointestinal cancer.

Case Presentation: A 63-year-old man underwent esophagogastroduodenoscopy because of anemia and hypoalbuminemia during a follow-up for gastric polyposis, which showed multiple reddish polyps and two elevated lesions in the stomach.

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The prevailing model of the primate auditory cortex proposes a core-belt-parabelt structure. The model proposes three auditory areas in the lateral belt region; however, it may contain more, as this region has been mapped only at a limited spatial resolution. To explore this possibility, we examined the auditory areas in the lateral belt region of the marmoset using a high-resolution optical imaging technique.

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Neurobehavioral abnormalities are commonly associated with intractable childhood epilepsy. Studies from numerous labs have demonstrated cognitive and socialization deficits in rats and mice that have experienced early-life seizures. However, the cellular and molecular mechanisms underlying these effects are unknown.

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Background: In patients with diabetes, albuminuria is a risk marker of end-stage renal disease and cardiovascular events. An increased renin-angiotensin system activity has been reported to play an important role in the pathological processes in these conditions. We compared the effect of aliskiren, a direct renin inhibitor (DRI), with that of angiotensin receptor blockers (ARBs) on albuminuria and urinary excretion of angiotensinogen, a marker of intrarenal renin-angiotensin system activity.

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This study aimed to identify the parietal ventral (PV) area of the somatosensory cortex in mice and to determine whether auditory cortex and somatosensory cortex overlap. Using high resolution, voltage-sensitive dye-based imaging, we identified the PV area, which exhibited strong responses to stimulation of distal body parts but weak responses to stimulation of proximal and facial body parts. We further demonstrated a substantial overlap between the auditory and non-primary somatosensory areas, including the PV area.

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Here we studied the auditory thalamic input to the insular cortex using mice as a model system. An insular auditory field (IAF) has recently been identified in mice. By using retrograde neuronal tracing, we identified auditory thalamic neurons projecting to the IAF, primary auditory cortex (AI), and anterior auditory field (AAF).

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Although orderly representation of sound frequency over space is a hallmark feature of the primary auditory cortex (A1), the quantitative relationship between sound frequency and cortical position is unclear. We examined this relationship in the guinea pig A1 by presenting a series of stimulus tones with a wide frequency range, and recording the evoked cortical responses using an optical imaging technique with high spatial resolution. We identified the cortical positions of three best-frequency indices for each tone: the onset response position, the peak amplitude position, and the maximum rise rate position of the response.

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Severe childhood epilepsy is commonly associated with intellectual developmental disabilities. The reasons for these cognitive deficits are likely multifactorial and will vary between epilepsy syndromes and even among children with the same syndrome. However, one factor these children have in common is the recurring seizures they experience - sometimes on a daily basis.

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Recent studies in humans and monkeys have reported that acoustic stimulation influences visual responses in the primary visual cortex (V1). Such influences can be generated in V1, either by direct auditory projections or by feedback projections from extrastriate cortices. To test these hypotheses, cortical activities were recorded using optical imaging at a high spatiotemporal resolution from multiple areas of the guinea pig visual cortex, to visual and/or acoustic stimulations.

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Sphingomyelin (SM) is a sphingolipid reported to function as a structural component of plasma membranes and to participate in signal transduction. The role of SM metabolism in the process of hearing remains controversial. Here, we examined the role of SM synthase (SMS), which is subcategorized into the family members SMS1 and SMS2, in auditory function.

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Childhood epilepsy can be severe and even catastrophic. In these instances, cognition can be impaired-leading to long-term intellectual disabilities. One factor that could potentially cause cognitive deficits is the frequent seizures that characterize intractable epilepsy.

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We used voltage-sensitive-dye-based imaging techniques to identify and characterize the insular auditory field (IAF) in mice. Previous research has identified five auditory fields in the mouse auditory cortex, including the primary field and the anterior auditory field. This study confirmed the existence of the primary field and anterior auditory field by examining the tonotopy in each field.

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Impaired learning and memory are common in epilepsy syndromes of childhood. Clinical investigations suggest that the developing brain may be particularly vulnerable to the effects of intractable seizure disorders. Magnetic resonance imaging (MRI) studies have demonstrated reduced volumes in brain regions involved in learning and memory.

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In the primary auditory cortex (AI), a pure tone evokes propagating activity along a strip of the cortex. We have previously shown that focal activation of AI triggers autonomously propagating activity that resembles tone-evoked activity (Song et al., 2006).

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Experiments reported here were motivated by studies in both human epilepsy and animal models in which stunted dendritic arbors are observed. Our goal was to determine if chronic network hyperexcitability alters dendritic growth. Experiments were conducted in hippocampal slice cultures obtained from infant mice that express the fluorescent protein YFP in CA1 hippocampal pyramidal cells.

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We examined whether the use of non-steroidal anti-inflammatory drugs (NSAIDs) can affect the anemia and iron status of hemodialysis patients. We recruited patients from six dialysis centers who had undergone maintenance hemodialysis for at least four months. We examined the use of NSAIDs during the past three months based on their medical records and assigned the patients to three groups (group A, non-NSAID group; group B, aspirin group; and group C, non-aspirin NSAID group).

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Recent studies have shown that metabolic syndrome is associated with an increased risk for chronic kidney disease. We recently found that the prevalence of sodium-sensitive hypertension in patients with metabolic syndrome was significantly higher than that in patients with essential hypertension but without metabolic syndrome. We therefore assessed the effects of benidipine, a long-acting calcium channel blocker, on the sodium sensitivity of blood pressure and renal hemodymamics in 5 patients with metabolic syndrome.

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X-linked dystonia-parkinsonism (XDP) is a movement disorder endemic to the Philippines. The disease locus, DYT3, has been mapped to Xq13.1.

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In guinea pig auditory cortex, two core areas, a primary area (AI) and a dorsocaudal field (DC), and two belt regions ventral to AI and DC (VRB and VCB) with an intermediate zone (T) in between, together with a small field (S) rostral to AI, have been reported in single-electrode studies although field S and zone T have not been observed in imaging studies. Using a high-resolution in vivo optical-imaging system with the voltage-sensitive dye RH-795, we report here the successful imaging of a rostral small field and zone T and a ventral-to-dorsal frequency gradient in zone T. Further, we found that VRB can be subdivided into two areas, a ventrorostral field (VR) with properties similar to those reported for VRB, and a ventrocaudal field (VC) with novel properties.

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