Biomedical subjects

Akihiro Inoue

Publications and source records attributed to Akihiro Inoue.

11 recordsLinked to original sources

PubMed2006

Differential control of postsynaptic density scaffolds via actin-dependent and -independent mechanisms.

Organization and dynamic remodeling of postsynaptic density (PSD) are thought to be critical in postsynaptic signal transduction, but the underlying molecular mechanisms are not well understood. We show here that four major scaffolding molecules, PSD-95, GKAP, Shank, and PSD-Zip45, show distinct instability in total molecular content per synapse. Fluorescence recovery after photobleaching also confirmed their distinct turnover rates. Among the PSD molecules examined, PSD-95 was most stable, but its elimination did not influence the dynamics of its direct binding partner GKAP. Multiple interactions of scaffolding molecules with the actin cytoskeleton have suggested their importance in both maintenance and remodeling of the PSD. Indeed, acute pharmacological disruption of F-actin rapidly eliminated the dynamic fraction of GKAP, Shank, and PSD-Zip45, without changing synaptic localization of PSD-95. GKAP content in synapses increased after pharmacological enhancement of neuronal activity, whereas Shank and PSD-Zip45 content showed reduction. Inhibition of F-actin dynamics prevented activity-dependent redistribution of all three scaffolds. We also assessed involvement of glutamate receptors in the regulation of PSD dynamics. Genetic manipulations eliminating either NMDA receptors or metabotropic glutamate receptors did not primarily influence mobility of their binding scaffolds. These results collectively indicate a critical role of filamentous actin in determining the extent of dynamic reorganization in PSD molecular composition.

Actins↗

PubMed2006

[A case of emergency carotid endarterectomy for severe stenosis of the cervical internal carotid artery presenting with progressing stroke: importance of managing blood pressure postoperatively].

We report a case treated successfully by emergency carotid endarterectomy (CEA) for progressing stroke resulting from pseudo-occlusion of the internal carotid artery (ICA). A 67-year-old male was admitted to our hospital with dysarthria. Neurological examination on admission revealed mild left-sided motor weakness and dysarthria. Computed tomography (CT) showed cerebral infarction in the territory of the perforating artery of right middle cerebral artery (MCA). Magnetic resonance (MR) imaging indicated similar findings and cervical MR angiography revealed occlusion of right cervical ICA. Cerebral conventional angiography and CT angiography revealed pseudo-occlusion of the right ICA. ECD-single photon emission tomography (SPECT) indicated low perfusion in the territory of the right ICA. Conservative therapy was performed using free radical scavengers and antiplatelet drugs, but neurological signs deteriorated. Revascularization using CEA was therefore performed. After surgery, the patient was restless with neurological abnormalities, and trans-cranial Doppler (TCD), INVOS-3100 and MRA revealed hyperperfusion. Strict control of blood pressure under propofol anesthesia allowed effective management of hyperperfusion syndrome. After a 1-month follow-up period, the patient was discharged with only mild left hemiparesis.

Aged↗

PubMed2006

[Case of clipping of a ruptured aneurysm of the posterior cerebral artery (P2) via the transchoroidal-fissure approach].

A 59-year-old female was found to be drawn in a swimming pool and transferred to our hospital. The patient was comatose on admission (Hunt & Kosnk: Grade IV). Computed tomography (CT) showed diffuse subarachnoid hemorrhage (SAH) with thick hematoma in the left ambient cistern. Conventional cerebral angiography and 3D-digital subtraction angiography revealed aneurysms (ANs) of the left posterior cerebral artery (P2), and bifurcation of the left internal carotid and posterior communicating arteries (IC-PC). Successful neck clipping was performed the same day through the temporal horn via the insula for ruptured P2 AN, and the non-ruptured IC-PC AN was also obliterated using a pterional approach. Postoperative course was uneventful except for initial disturbance of consciousness and aphasia. The patient was discharged with no neurological deficit 1 month after surgery. This approach may be preferable in cases involving high positioned PCA AN in the ambient cistern, particularly in the acute phase of severe SAH, as the brain is protected from the detrimental effects of strong temporal retraction and a wider working space is provided.

Aneurysm, Ruptured↗

PubMed2006

[A case of high-aged idiopathic spinal cord herniation from dural defect].

Idiopathic spinal cord herniation was assumed to be a rare disease. However, the incidence of discovering this condition appears to have been increasing recently with advances in neuroradiological diagnosis using magnetic resonance imaging (MRI) and computed tomographic myelogram (CTM). We present herein an operated case of high-aged idiopathic spinal cord herniation. A 71-year-old female presented with spastic paresis of the right lower limb and sensory disturbance of pain and temperature below the level of the left Th4 dermatome, consistent with Brown-Séquard syndrome. MRI and CTM revealed right ventral displacement of the spinal cord and dilatation of the dorsal subarachnoid space at Th2/3. Laminectomy of Th1-3 was performed, herniated spinal cord was untethered and repositioned, and the dural defect was sealed with GORE-TEX dura substitute. Postoperative MRI revealed normal location of the spinal cord and neurological state improved slightly. The patient was discharged 1 month after the operation. Among many cases of spinal cord herniations, this is considered to be a rare case of idiopathic spinal cord herniation in an elderly patient.

Aged↗

PubMed2006

[Two cases of main trunk artery occlusion associated with multiple cerebral aneurysms].

We report 2 cases of multiple aneurysms (AN) associated with main trunk artery occlusion. CASE 1: A 52-year-old male was admitted to our hospital with dysarthria and weakness of the right side of the body. Computed tomography (CT) showed cerebral infarction in the left corona radiata. MR angiography and conventional angiography showed occlusion of the left middle cerebral artery (MCA) and saccular aneurysms (ANs) at the origin of the anterior communicating artery (A-com) and bifurcation of the right MCA. Subsequent 123I-IMP-single photon emission tomography (SPECT) revealed marked reduction of cerebral blood flow and disturbed reactivity to acetazolamide in the left cerebral hemisphere. Superficial temporal artery (STA)-MCA anastomosis was performed to improve cerebral blood flow and reduce hemodynamic stress for AN of the A-com and right MCA. At 5 months after the first operation, neck clipping was performed successfully for the non-ruptured A-com AN and right MCA AN. CASE 2: A 65-year-old male was admitted to our hospital. CT revealed subarachnoid hemorrhage (SAH), and 3D-computed tomographic angiography (CTA) and cerebral angiography showed basilar top AN, A-com AN and right MCA AN associated with right internal carotid artery occlusion. Right ACA and MCA territories were visualized from the A-com artery and posterior cerebral artery. STA-MCA anastomosis was performed to improve cerebral blood flow and reduce hemodynamic stress for ANs. In the same operation, successful neck clipping was performed for BA top AN and right MCA AN. In such cases as these, particularly in ischemic cases associated with main trunk artery occlusion, it was important to consider surgery for AN after STA-MCA anastomosis in anticipation of improved cerebral blood flow and reduce hemodynamic stress for AN.

Aged↗

PubMed2005

Bi-directional regulation of postsynaptic cortactin distribution by BDNF and NMDA receptor activity.

Abstract Cortactin is an F-actin-associated protein which interacts with the postsynaptic scaffolding protein Shank at the SH3 domain and is localized within the dendritic spine in the mouse neuron. Green fluorescent protein (GFP)-based time-lapse imaging revealed cortactin redistribution from dendritic cytoplasm to postsynaptic sites by application of brain-derived neurotrophic factor (BDNF). This response was mediated by mitogen-activated protein (MAP) kinase activation and was dependent on the C-terminal SH3 domain. In contrast, activation of N-methyl-D-aspartate (NMDA) receptors induced loss of cortactin from postsynaptic sites. This NMDA-dependent redistribution was blocked by an Src family kinase inhibitor. Conversely, increasing Src family kinase activity induced cortactin phosphorylation and loss of cortactin from the postsynaptic sites. Finally, blocking of endogenous BDNF reduced the amount of cortactin at the postsynaptic sites and an NMDA receptor antagonist prevented this reduction. These results indicate the importance of counterbalance between BDNF and NMDA receptor-mediated signalling in the reorganization of the postsynaptic actin cytoskeleton during neuronal development.

2-Amino-5-phosphonovalerate↗

PubMed2005

[A case of common carotid artery dissection showing remission in short-term].

We report a case of left common carotid artery dissection showing complete remission in the short term. A 48-year-old man presented a 1-week history of weakness in the right arm. Neurological findings revealed mild motor weakness of the right upper extremity. Magnetic resonance imaging (MRI) showed sporadic cerebral infarction and hemorrhagic infarction in the area of the left middle cerebral artery (MCA) and the posterior border zone. Computed tomographic angiography (CTA) revealed irregular stenosis with a smooth surface in the left common carotid artery and ultrasonography indicated an iso-echoic lesion in the same area. ECD-single-photon emission tomography (SPECT) showed low perfusion only in the infarcted territory. Conservative therapy using a free radical scavenger and aspirin was carried out and the patient displayed full neurological recovery. After a 3-week follow-up period, carotid angiography and CTA showed almost complete disappearance of the stenotic lesion.

Aortic Dissection↗

PubMed2005

[A case involving complete removal of C2 dumbbell type neurinoma with preservation of the surrounding supportive tissue].

We report a case in which C2 neurinoma was completely removed with preservation of the surrounding supportive tissue. A 47-year-old female was admitted to our hospital with gait disturbance and spinal tumor identified in other hospital. Neurological examination on admission revealed hyperreflexia in bilateral limbs and pathological reflexes. Cervical plain X-radiography showed erosion of the left C2 lamina. Axial Gd-enhanced T1 weighted magnetic resonance (MR) images showed partial enhancement of a dumbbell shaped tumor at the C1-2 level, revealing compression of the spinal cord to the right and extending to postero-laterally, and coronal MR images demonstrated that the tumor was clearly surrounded by the semispinalis capitis, semispinalis cervicis and inferior oblique muscles. The tumor was resected through a posterior approach without injuring the surrounding supportive tissue. Post operatively, she did not complain of nuchal pain during neck movement. After a 6-month follow-up period, cervical plain X-radiography showed preservation of cervical alignment, and coronal Gd-enhanced T1-weighted MR images demonstrated preservation of the posterior group of cervical muscles. It is desirable to preserve the surrounding supportive tissue as far as possible in order to minimize the postoperative neck pain and instability of cervical spine, like this case.

Cervical Vertebrae↗

PubMed2004

Estimation of the impact of providing outpatients with information about SARS infection control on their intention of outpatient visit.

To examine the effect of provision of information about the infection control in the specific infection disease treatment unit in a city hospital on the outpatient's intention of outpatient service use, respondents who underwent outpatient medical care at the hospital (N = 821) were asked whether or not they intended to continue the outpatient visit at the hospital if a severe acute respiratory syndrome (SARS) patient was admitted to the unit. Although 56% of respondents replied that they could continue to visit the department if a SARS patient was admitted to the unit in the hospital before they read the information, the proportion of those who intended to continue outpatient care significantly increased by 15% after they read it. The logistic regression analyses revealed that respondents who had frequently visited the outpatient department (P < 0.001), those who felt relieved by reading the information about the unit (P < 0.001), and those who did not worry about nosocomial SARS infection inside the hospital (P < 0.001) were significantly more likely to reply that they would continue outpatient visits. We estimated that admission of a SARS patient to the unit would result in a 20% decrease in the cumulative total number of outpatients in the hospital during a 180-day interval after admission of a SARS patient to the unit, and the cumulative total number of outpatients increased by 7% after they read the information. This study suggests that providing outpatients with appropriate information about SARS infection control in the hospital had a statistically significant and substantial impact on the outpatients' intention to continue outpatient visits at the hospital.

Cross Infection↗

PubMed2003

p250GAP, a novel brain-enriched GTPase-activating protein for Rho family GTPases, is involved in the N-methyl-d-aspartate receptor signaling.

N-methyl-d-aspartate (NMDA) receptors regulate structural plasticity by modulating actin organization within dendritic spines. Herein, we report identification and characterization of p250GAP, a novel GTPase-activating protein for Rho family proteins that interacts with the GluRepsilon2 (NR2B) subunit of NMDA receptors in vivo. The p250GAP mRNA was enriched in brain, with high expression in cortex, corpus striatum, hippocampus, and thalamus. Within neurons, p250GAP was highly concentrated in the postsynaptic density and colocalized with the GluRepsilon2 (NR2B) subunit of NMDA receptors and with postsynaptic density-95. p250GAP promoted GTP hydrolysis of Cdc42 and RhoA in vitro and in vivo. When overexpressed in neuroblastoma cells, p250GAP suppressed the activities of Rho family proteins, which resulted in alteration of neurite outgrowth. Finally, NMDA receptor stimulation led to dephosphorylation and redistribution of p250GAP in hippocampal slices. Together, p250GAP is likely to be involved in NMDA receptor activity-dependent actin reorganization in dendritic spines.

Actins↗

PubMed2003

The dynamic organization of postsynaptic proteins: translocating molecules regulate synaptic function.

Physiological roles for postsynaptic molecules in synaptogenesis and plasticity are under intense investigation. Recent imaging experiments, including GFP-based and single-particle tracking strategies, reveal rapid movement of synaptic components to and from the postsynaptic sites. Furthermore, specific patterns of neuronal activity and/or activation of specific transmitter receptors trigger selective translocation of postsynaptic components. These emerging dynamic properties of synaptic specializations add another layer of complexity to the signaling mechanisms of CNS synapses.

Animals↗