Publications by authors named "Masami Takahashi"

Objectives: This study aimed to compare the extracellular matrix of primary cartilage with the secondary cartilage of chicks using immunohistochemical analyses in order to understand the features of chick secondary chondrogenesis.

Methods: Immunohistochemical analysis was performed on the extracellular matrix of quadrate (primary), squamosal, surangular, and anterior pterygoid secondary cartilages using various antibodies targeting the extracellular matrix of cartilage and bone.

Results: The localization of collagen types I, II, and X, versican, aggrecan, hyaluronan, link protein, and tenascin-C was identified in the quadrate cartilage, with variations within and between the regions.

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Cluster of differentiation 146 (CD146) is known to localize in stem cells and precursor cells of various tissues. In this study, to analyze the function of CD146 in odontoblast differentiation, immunohistochemical localization of CD146 was examined during rat molar tooth development and after cavity preparation. At the cap and bell stages, many CD146-positive cells were visible around the blood vessels in the dental papillae.

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This study explored end-of-life (EOL) activities among community-dwelling Japanese older adults and the relationships between EOL activities and related variables. One hundred twenty-three older adults (38 men, 87 women; mean age = 72.54 years) who attended EOL seminars were surveyed regarding EOL activities, attitudes toward death, and mental health status.

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Youth encounter issues of religion in the process of identity formation. However, most prior studies have focused on Christian youth in Western counties. This study examined the relationship between identity formation and religious beliefs in the Eastern national context where Buddhism and non-institutional folk religions are prevalent.

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Neurotransmitter release is mediated by the SNARE complex, but the role of its phosphorylation has scarcely been elucidated. Although PKC activators are known to facilitate synaptic transmission, there has been a heated debate on whether PKC mediates facilitation of neurotransmitter release through phosphorylation. One of the SNARE proteins, SNAP-25, is phosphorylated at the residue serine-187 by PKC, but its physiological significance has been unclear.

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Background: To elucidate mechanisms of epileptogenesis and epileptic maturation, and to develop new AEDs, it is indispensable to administer various drugs and to examine their effects on EEG over a long period of observation.

New Method: We constructed a device for the continuous measurement of electroencephalography (EEG) and the infusion of anti-epileptic drugs over a prolonged period of time in moving mice. The system includes a slip ring and a swivel to prevent twisting of the recording cable and infusion tube, respectively.

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SNAP-25 is a neurotransmitter vesicular docking protein which has been associated with brain disorders such as attention deficit hyperactivity disorder, bipolar disorder and schizophrenia. In this project, we were interested if clinical factors are associated with differential SNAP-25 expression. We examined the SNAP-25 isoform mRNA and protein levels in postmortem cortex Brodmann's area 9 (BA9) and BA24 (n = 29).

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A mouse model of epilepsy was generated by inducing status epilepticus (SE) for either 1.5 or 4.5h with pilocarpine to study anxiety-related behaviors, changes in the electroencephalogram of the cerebral cortex and hippocampus, and expression of hippocampal proteins.

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VAMP7 is a SNARE protein that mediates specific membrane fusions in intracellular trafficking and was recently reported to regulate autophagosome formation. However, its function in pancreatic β-cells is largely unknown. To elucidate the physiological role of VAMP7 in β-cells, we generated pancreatic β-cell-specific VAMP7 knockout (Vamp7(flox/Y);Cre) mice.

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Nitrated guanine nucleotide 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP) generated by reactive oxygen/nitrogen species causes protein S-guanylation. However, the mechanism of 8-nitro-cGMP formation and its protein targets in the normal brain have not been identified. Here, we investigated 8-nitro-cGMP generation and protein S-guanylation in the rodent brain.

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Snap25(S187A/S187A) mouse is a knock-in mouse with a single amino acid substitution at a protein kinase C-dependent phosphorylation site of the synaptosomal-associated protein of 25 kDa (SNAP-25), which is a target-soluble NSF attachment protein receptor (t-SNARE) protein essential for neurotransmitter release. Snap25(S187A/S187A) mice exhibit several distinct phenotypes, including reductions in dopamine and serotonin release in the brain, anxiety-like behavior, and cognitive dysfunctions. Homozygous mice show spontaneous epileptic convulsions, and about 15% of the mice die around three weeks after birth.

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Article Synopsis
  • The pro-peptide of brain-derived neurotrophic factor (BDNF) is produced alongside its mature form but its biological functions are not well understood.
  • Research shows the BDNF pro-peptide is expressed in hippocampal tissues and enhances long-term depression (LTD) through specific receptor activation.
  • The presence of a specific BDNF genetic variant (Val66Met) negatively impacts hippocampal LTD, linking the pro-peptide's role in synaptic plasticity to memory function in humans.
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Susceptible healthcare personnel (HCP) are at high risk for acquiring and transmitting measles, mumps, rubella, and varicella (MMRV). Presumptive evidence of immunity to MMRV is recommended for HCP. The aim of this investigation was to examine the seroprevalence of MMRV in Japanese HCP and the association with history or vaccination in terms of occupational safety.

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Protein tyrosine kinases, which are highly expressed in the central nervous system, are implicated in many neural processes. However, the relationship between protein tyrosine kinases and neurotransmitter release remains unknown. In this study, we found that ionomycin, a Ca²⁺ ionophore, concurrently induced asynchronous neurotransmitter release and phosphorylation of a non-receptor protein tyrosine kinase, proline-rich tyrosine kinase 2 (Pyk2), in clonal rat pheochromocytoma PC12 cells and cerebellar granule cells, whereas introduction of Pyk2 siRNA dramatically suppressed ionomycin-induced neurotransmitter release.

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Transmembrane α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor regulatory proteins (TARPs) are auxiliary subunits that regulate AMPA receptor trafficking to the plasma membrane and localization to postsynaptic sites. The classical TARP family consists of four members: stargazin/γ-2, γ-3, γ-4 and γ-8. The TARP γ-8 isoform, which is highly expressed in the hippocampus, has a unique, long C-terminal domain with five distinct regions: two glycine-rich regions, a serine/arginine-rich region, a proline/alanine (P/A) rich region, and a PSD-95/Dlg/ZO-1 (PDZ) binding motif.

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Synaptosomal-associated protein of 25 kDa (SNAP-25), a t-SNARE protein, plays a crucial role in neurotransmitter release by exocytosis. Protein kinase C phosphorylates SNAP-25 at Ser(187), however the physiological significance of this phosphorylation event in brain function remains unclear. In the present study, we found that SNAP-25 phosphorylation increased rapidly in the mouse brain following cold-water restraint stress.

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The purpose of this study was to determine whether calmodulin (CaM) plays a role in neurotransmitter release by examining the effect that ophiobolin A (OBA), a CaM antagonist, on neurotransmitter release from clonal rat pheochromocytoma PC12 cells, primary cortical neurons, and primary cerebellar granule cells. OBA inhibited Ca²⁺/CaM-dependent phosphorylation of cAMP response element binding protein in all cell types tested. Moreover, Ca²⁺-dependent release of dopamine and acetylcholine from PC12 cells were remarkably reduced by OBA in a dose-dependent and temporal manner, but neurotransmitter release partially recovered with the addition of CaM in membrane permeabilized PC12 cells.

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Calnexin is a molecular chaperone that resides in the endoplasmic reticulum and participates in the folding and assembly of nascent proteins. In the present study, calnexin was found in both synaptic and non-synaptic membrane components of rat brain tissue. Immunohistochemical staining of mouse hippocampal sections revealed the presence of calnexin in the neuronal cell soma, as well as dendrite-enriched regions.

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Background: Synaptosomal-associated protein, 25 kDa (SNAP-25) regulates the exocytosis of neurotransmitters. Growing evidence suggests that SNAP-25 is involved in neuropsychiatric disorders, such as schizophrenia, attention-deficit/hyperactivity disorder, and epilepsy. Recently, increases in anxiety-related behaviors and epilepsy have been observed in SNAP-25 knock-in (KI) mice, which have a single amino acid substitution of Ala for Ser187.

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Synaptosomal-associated protein 25 (SNAP-25) plays an essential role in exocytotic neurotransmitter release as a t-SNARE protein. SNAP-25 is phosphorylated at Ser(187) in a protein kinase C (PKC)-dependent manner, but the mechanism for dephosphorylation has yet to be clarified. We investigated SNAP-25 dephosphorylation by comparing it to growth associated protein 43 (GAP-43), another PKC-dependent presynaptic phosphoprotein, in crude mouse brain synaptosome preparations.

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Pathological examination of dementia with Lewy bodies patients identified the presence of abnormal α-synuclein (αSyn) aggregates in the presynaptic terminals. αSyn is involved in the regulation of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex. Importantly, αSyn-transgenic mouse and postmortem examination of patients with Parkinson's disease have demonstrated the abnormal distribution of SNARE protein in presynaptic terminals.

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Ipsilateral and contralateral hippocampal CA3-CA1 and CA2-CA1 projections were investigated in adult male Long-Evans rats by retrograde tracing. Injection of the retrograde tracer cholera toxin subunit B in the strata oriens and radiatum of dorsal CA1 resulted in labeling of predominantly pyramidal cells in ipsilateral and contralateral CA3 and CA2. The contralateral and ipsilateral anterior-posterior extents of CA3 innervation to CA1 were similar.

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The Ca(2+) -dependent activator protein for secretion (CAPS) family consists of two members (CAPS1 and CAPS2) and regulates the exocytosis of catecholamine-containing or neuropeptide-containing dense-core vesicles (DCVs) at secretion sites such as nerve terminals. A large fraction of CAPS1, however, is localized in the cell soma, and we have recently shown the possible involvement of somal CAPS1 in DCV trafficking in the trans-Golgi network. CAPS1 and CAPS2 are differentially expressed in various regions of the mouse brain but exhibit similar expression patterns in other tissues, such as the spleen.

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Synaptosomal-associated protein of 25 kDa (SNAP-25) is a presynaptic protein essential for neurotransmitter release. Previously, we demonstrate that protein kinase C (PKC) phosphorylates Ser(187) of SNAP-25, and enhances neurotransmitter release by recruiting secretory vesicles near to the plasma membrane. As PKC is abundant in the brain and SNAP-25 is essential for synaptic transmission, SNAP-25 phosphorylation is likely to play a crucial role in the central nervous system.

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Soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP)-25 is a neuronal SNARE protein essential for neurotransmitter release from presynaptic terminals. Three palmitoylated SNAP-25 family proteins: SNAP-25a, SNAP-25b, and SNAP-23, are expressed in the brain, but little is known about their distributions and functions. In the present study, we generated specific antibodies to distinguish these three homologous proteins.

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