Kenshi Kuma, Junya Tanaka, Kensuke Matsunaga, Katsuhiko Matsunaga,
Recent studies point out that dissolved iron in seawater is bound to strong organic complexes that have stability constants consistent with microbially produced siderophores. In the present study, the growth and iron uptake of the coastal marine diatom Chaetoceros sociale were experimentally measured in culture experiments at 10°C in media containing a terrestrial fungal hydroxamate ferrisiderophore, desferriferrichrome (DFC)‐Fe(III) (2 DFC:1 Fe and 10 DFC:1 Fe) complex with an Fe concentration of ...
Tópico(s): Marine and coastal ecosystems
2000 - Wiley | Limnology and Oceanography
Hiroki Nakatsuka, Shinsuke Ohta, Junya Tanaka, Kazuko Toku, Yoshiaki Kumon, Nobuji Maeda, Masahiro Sakanaka, Saburo Sakaki,
We examined cytosolic cytochrome c in gerbil hippocampal CA1 and CA3 regions after induction of 5-min ischemia by immunoblotting. In the CA1 region, cytochrome c was detected in the cytosolic fraction from 1 to 6 h after ischemia by Western blotting, while it was not detected in the CA3 region. Following intraventricular administration of cyclosporin A (CsA), detectable cytosolic cytochrome c was dramatically decreased, and about 80% of CA1 neurons survived after ischemia. The present studies demonstrate ...
Tópico(s): Alzheimer's disease research and treatments
1999 - Elsevier BV | Brain Research
Junya Tanaka, Kazuko Toku, Masahiro Sakanaka, Nobuji Maeda,
It is believed that ramified resting microglial cells in the brain are differentiated from macrophage-like ameboid cells, although the mechanism for the differentiation is not fully understood. In the present study, we investigated whether the differentiation of microglial cells is observable in mixed brain cell culture prepared from newborn rat forebrains. In confluent mixed brain cell culture, both ramified and ameboid microglial cells were simultaneously present. The ramified cells were located ...
Tópico(s): S100 Proteins and Annexins
1999 - Elsevier BV | Neuroscience Research
Keiji Igase, Junya Tanaka, Yoshiaki Kumon, Bo Zhang, Yasutaka Sadamoto, Nobuji Maeda, Saburo Sakaki, Masahiro Sakanaka,
It was previously reported that prosaposin possesses neurotrophic activity that is ascribed to an 18-mer peptide comprising the hydrophilic sequence of the rat saposin C domain. To evaluate the effect of the 18-mer peptide on ischemic neuronal damage, the peptide was infused in the left lateral ventricle immediately after occlusion of the left middle cerebral artery (MCA) in stroke-prone spontaneously hypertensive (SP-SH) rats. The treatment ameliorated the ischemia-induced space navigation disability ...
Tópico(s): Neurobiology and Insect Physiology Research
1999 - SAGE Publishing | Journal of Cerebral Blood Flow & Metabolism
Kenshi Kuma, Junya Tanaka, K. Matsunaga,
Tópico(s): Aquatic Ecosystems and Phytoplankton Dynamics
1999 - Springer Science+Business Media | Marine Biology
Junya Tanaka, Kazuko Toku, Bo Zhang, Ken Ishihara, Masahiro Sakanaka, Nobuji Maeda,
Reactive oxygen and nitrogen species (RO/NS) such as nitric oxide (NO), hydroxyl radical (OH·), and superoxide anion (O2−) are generated in a variety of neuropathological processes and damage neurons. In the present study, we investigated the neuroprotective effects of rat astrocytes against RO/NS-induced damage using neuron–glia cocultures, and the effects were compared to those of microglial cells. Sodium nitroprusside (SNP), 3-morpholinosydnonimine (SIN-1), and FeSO4 were used to generate NO, O2− and ...
Tópico(s): Barrier Structure and Function Studies
1999 - Wiley | Glia
Hui Peng, Tong‐Chun Wen, Junya Tanaka, Nobuji Maeda, Seiji Matsuda, Junzo Desaki, Satoko Sudo, Bo Zhang, Masahiro Sakanaka,
Epidermal growth factor (EGF) has been considered to be a candidate for neurotrophic factors on the basis of the results of several in vitro studies. However, the in vivo effect of EGF on ischemic neurons as well as its mechanism of action have not been fully understood. In the present in vivo study using a gerbil ischemia model, we examined the effects of EGF on ischemia-induced learning disability and hippocampal CA1 neuron damage. Cerebroventricular infusion of EGF (24 or 120 ng/d) for 7 days to ...
Tópico(s): Neuroinflammation and Neurodegeneration Mechanisms
1998 - SAGE Publishing | Journal of Cerebral Blood Flow & Metabolism
Kazuko Toku, Junya Tanaka, Hajime Yano, Junzo Desaki, Bo Zhang, Lihua Yang, Ken Ishihara, Masahiro Sakanaka, Nobuji Maeda,
Apoptotic neuronal death is known to occur in the developing brain and in the mature brain of patients with ischemic and degenerative disorders. Although microglial cells are known to become activated in specific conditions, it has not been elucidated whether they enhance or prevent neuronal apoptosis. The present study was intended to observe how microglial cells are involved in neuronal death. When rat primary cortical neurons were incubated with a nitric oxide (NO) donor sodium nitroprusside (SNP; ...
Tópico(s): Atherosclerosis and Cardiovascular Diseases
1998 - Wiley | Journal of Neuroscience Research
Hiroko Fujita, Junya Tanaka, Nobuji Maeda, Masahiro Sakanaka,
The effects of several cyclic adenosine monophosphate (cAMP)-elevating agents on the proliferation of cultured rat microglia were investigated by immunocytochemical staining with an antibody against proliferating cell nuclear antigen (PCNA). Epinephrine, isoproterenol, forskolin and 8Br-cAMP suppressed the microglial proliferation. A β2-selective agonist terbutaline but not a β1-selective agonist dobutamine mimicked the effect of the above cAMP-elevating agents. Furthermore, a non-selective β-receptor ...
Tópico(s): Receptor Mechanisms and Signaling
1998 - Elsevier BV | Neuroscience Letters
Junya Tanaka, Kazuko Toku, Seiji Matsuda, Satoko Sudo, Hiroko Fujita, Masahiro Sakanaka, Nobuji Maeda,
Cultured microglial cells usually exhibit ameboid morphology and peripheral macrophage-like properties, which are distinct from those observed in the normal mature brain. This might be caused by the inappropriate culture of microglial cells in high concentrations (approximately 200-400 microM) of Gly and Ser, although the concentrations of the amino acids in extracellular spaces of the brain parenchyma are quite low (approximately 5 microM). In the present study, we focused on the concentration-dependent ...
Tópico(s): Alzheimer's disease research and treatments
1998 - Wiley | Glia
Bo Zhang, Seiji Matsuda, Junya Tanaka, Norihiko Tateishi, Nobuji Maeda, Tong‐Chun Wen, Hui Peng, Masahiro Sakanaka,
Oral administration of red ginseng powder before but not after transient forebrain ischemia prevents delayed neuronal death in gerbils. One neuroprotective molecule within red ginseng powder is ginsenoside Rb1. The mechanism of action(s) of ginsenoside Rb1 remains to be determined. We performed intracerebroventricular infusion of 0.6 μg/d ginsenoside Rb1 before or after permanent occlusion of the left middle cerebral artery in stroke-prone spontaneous hypertensive rats. Ginsenoside Rb1 significantly ...
Tópico(s): Biological and pharmacological studies of plants
1998 - Elsevier BV | Journal of Stroke and Cerebrovascular Diseases
Tong‐Chun Wen, Junya Tanaka, Hui Peng, Junzo Desaki, Seiji Matsuda, Nobuji Maeda, Hiroko Fujita, Kohji Sato, Masahiro Sakanaka,
In the central nervous system, interleukin (IL)-3 has been shown to exert a trophic action only on septal cholinergic neurons in vitro and in vivo, but a widespread distribution of IL-3 receptor (IL-3R) in the brain does not conform to such a selective central action of the ligand. Moreover, the mechanism(s) underlying the neurotrophic action of IL-3 has not been elucidated, although an erythroleukemic cell line is known to enter apoptosis after IL-3 starvation possibly due to a rapid decrease in ...
Tópico(s): Immune Response and Inflammation
1998 - Rockefeller University Press | The Journal of Experimental Medicine
Satoko Sudo, Junya Tanaka, Kazuko Toku, Junzo Desaki, Seiji Matsuda, Tatsuru Arai, Masahiro Sakanaka, Nobuji Maeda,
Although microglial cells are well known to become activated in the pathological brain, mechanisms underlying the microglial activation are not fully understood. In the present study, with an aim to elucidate whether neurons are involved in the microglial activation, we compared the morphology and the superoxide anion (O2−)-generating activity of rat microglial cells in pure culture with those of cells cocultured with rat primary cortical neurons. Microglial cells in pure culture in serum-free Eagle' ...
Tópico(s): Barrier Structure and Function Studies
1998 - Elsevier BV | Experimental Neurology
Lihua Yang, Junya Tanaka, Bo Zhang, Masahiro Sakanaka, Nobuji Maeda,
We investigated lipopolysaccharide (LPS)-induced nitric oxide (NO) production by rat microglia in neuron-microglia and astrocyte-microglia cocultures to evaluate the influence of neurons and astrocytes on microglial activity. Microglial cells solely cultured in medium devoid of serine (Ser), glycine (Gly) hardly expressed inducible NO synthase (iNOS), while those cocultured with neurons and astrocytes expressed iNOS. When microglial cells and astrocytes were separately cultured by using tissue culture ...
Tópico(s): Immune cells in cancer
1998 - Elsevier BV | Biochemical and Biophysical Research Communications
Satoko Sudo, Tong‐Chun Wen, Junzo Desaki, Seiji Matsuda, Junya Tanaka, Tatsuru Arai, Nobuji Maeda, Masahiro Sakanaka,
β-Estradiol has been considered to be a neurotrophic agent, but its in vivo effect on gerbils with transient forebrain ischemia has not yet been demonstrated. In the first set of the present experiments, we infused β-estradiol at a dose of 0.05 or 0.25 μg/day for 7 days into the lateral ventricles of normothermic gerbils starting 2 h before 3-min forebrain ischemia. β-Estradiol infusion at a dose of 0.25 μg/day prevented significantly the ischemia-induced reduction of response latency time as revealed ...
Tópico(s): Neurogenesis and neuroplasticity mechanisms
1997 - Elsevier BV | Neuroscience Research
Jung-Dae Lim, Tong Wen, Seiji Matsuda, Junya Tanaka, Nobuji Maeda, Hui Peng, Junko Aburaya, Ken Ishihara, Masahiro Sakanaka,
Our previous study showed that the oral administration of red ginseng powder before but not after transient forebrain ischemia prevented delayed neuronal death in gerbils, and that a neuroprotective molecule within red ginseng powder was ginsenoside Rb1. However, it remains to be clarified whether or not ginsenoside Rb1 acts directly on the ischemic brain, and the mechanism by which ginsenoside Rb1 protects the ischemic CA1 neurons is not determined. Without elucidation of the pharmacological property ...
Tópico(s): Biological and pharmacological studies of plants
1997 - Elsevier BV | Neuroscience Research
Junya Tanaka, Hiroko Fujita, Seiji Matsuda, Kazuko Toku, Masahiro Sakanaka, Nobuji Maeda,
Effects of steroid hormones on the regulation of function and morphology of microglial cells were investigated using the cultured cells isolated from forebrain of newborn rats. Cortisol, corticosterone, and aldosterone at 100 nM caused a strong shrinkage of microglial cells cultured in a serum-supplemented medium. However, cholesterol, pregnenolone, testosterone, estradiol, and dehydroepiandrosterone did not exhibit any significant effects. The corticosteroids also inhibited the GM-CSF-mediated ...
Tópico(s): Hormonal Regulation and Hypertension
1997 - Wiley | Glia
Norihiko Tateishi, Yoji Suzuki, Junya Tanaka, Nobuji Maeda,
ABSTRACT Objective : To construct images of oxygen saturation and the distribution of erythrocytes in a network of microvessels. Methods : The image of a small group of microvessels under an inverted microscope was incorporated into an image processor through a video camera and was digitized. Based on the information obtained through six visible interference filters of different wavelengths, oxygen saturation and the amount of erythrocytes in microvessels were calculated with a computer. The system ...
Tópico(s): Hemoglobin structure and function
1997 - Wiley | Microcirculation
Junya Tanaka, M. Markerink–van Ittersum, Harry W.M. Steinbusch, Jan de Vente,
We investigated the nature of cGMP-synthesizing cells in the developing rat forebrain using cGMP-immunocytochemistry in combination with in vitro incubation of brain slices. When brain slices of immature rats, aged between 1 and 4 weeks, were incubated with sodium nitroprusside (SNP), a nitric oxide (NO) donor compound, in the presence of the phosphodiesterase inhibitor isobutylmethylxanthine (IBMX), small round cells with a few processes in and around the corpus callosum were visualized with the cGMP- ...
Tópico(s): Adenosine and Purinergic Signaling
1997 - Wiley | Glia
Nobuji Maeda, Yoshio Suzuki, Junya Tanaka, Norihiko Tateishi,
Flow dynamics of human erythrocytes was compared in elastic (E) and hardened (H) microvessels with inner diameters of 10-40 microns. The thickness of the marginal cell-free layer and the overall flow resistance were measured with a vascular bed isolated from rabbit mesentery (E vascular bed) as well as with a 4% paraformaldehyde-fixed bed (H vascular bed). 1) In both E and H microvessels, the thickness of the cell-free layer increased with increasing inner diameter of the microvessels and with decreasing ...
Tópico(s): Platelet Disorders and Treatments
1996 - American Physical Society | AJP Heart and Circulatory Physiology
Hiroko Fujita, Junya Tanaka, Kazuko Toku, Norihiko Tateishi, Yoji Suzuki, Seiji Matsuda, Masahiro Sakanaka, Nobuji Maeda,
Microglia transform from ameboid to ramified cells during development and display an ameboid appearance again under certain pathological conditions. Some cytokines produced by astrocytes may be responsible for the microglial transformation. In the present study, we compared the effects of cytokines, granulocyte/macrophage colony-stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF), and interleukin-3 (IL-3) on the morphology of rat cultured microglia. For quantitative evaluation, ...
Tópico(s): Morinda citrifolia extract uses
1996 - Wiley | Glia
Yasunori Kotani, Seiji Matsuda, Tong‐Chun Wen, Masahiro Sakanaka, Junya Tanaka, Nobuji Maeda, Keiji Kondoh, Shuichi Ueno, Akira Sano,
Abstract: Prosaposin, a 517‐amino‐acid glycoprotein, not only acts as the precursor of saposin A, B, C, and D but also possesses neurotrophic activity to rescue hippocampal CA1 neurons from ischemic damage in vivo and to promote neurite extension of neuroblastoma cells in vitro. Recently, the trophic activity of prosaposin on human neuroblastoma cells has been shown to reside in the NH 2 ‐terminal hydrophilic sequence (LIDNNRTEEILY) of the human saposin C. Here we show that prosaposin, saposin C, ...
Tópico(s): Biochemical Analysis and Sensing Techniques
1996 - Wiley | Journal of Neurochemistry
It is generally accepted that process-bearing microglial cells originate from ameboid macrophage-like mesodermal cells. This transformation, often called ramification, accompanies down regulation of macrophage-like properties, but the mechanisms involved in ramification have not been clarified. We investigated factors to promote ramification in culture. Isolated ameboid microglial cells were seeded on living or paraformaldehyde-fixed astrocyte monolayers. About 80% of the cells ramified on the fixed ...
Tópico(s): Bone Tissue Engineering Materials
1996 - Elsevier BV | Experimental Neurology
T. Gotow, Junya Tanaka, Mamoru Takeda,
Neurofilaments accumulated in perikarya and dendrites of anterior horn cells and Purkinje cells of rabbit treated by aluminum chloride were analysed with a variety of techniques. Four different monoclonal antibodies against phosphorylated and nonphosphorylated epitopes on neurofilament H subunit were used to compare phosphorylation state of these accumulated neurofilaments with that of axonal neurofilaments. Although immunoblotting revealed no significant difference in phosphorylation between control ...
Tópico(s): Cellular Mechanics and Interactions
1995 - Elsevier BV | Neuroscience
Masahiro Kira, Junya Tanaka, Kenji Sobue,
Abstract Neuronal growth cones move actively, accompanying changes in intracellular Ca 2+ concentration. The movement of growth cones may partly depend on the actomyosin system, considering the presence of actin and myosin II. Yet, Ca 2+ ‐sensitive regulatory proteins for the actomyosin system have not been identified in growth cones. In the present study, caldesmon, an inhibitory protein on actin‐myosin interaction, was detected in the growth cone fraction isolated from embryonic rat brain, using ...
Tópico(s): Muscle Physiology and Disorders
1995 - Wiley | Journal of Neuroscience Research
Akihiro Inoue, Takanori Ohnishi, Masahiro Nishikawa, Yoshihiro Ohtsuka, Kosuke Kusakabe, Hajime Yano, Junya Tanaka, Takeharu Kunieda,
High invasiveness is a characteristic of glioblastoma (GBM), making radical resection almost impossible, and thus, resulting in a tumor with inevitable recurrence. GBM recurrence may be caused by glioma stem-like cells (GSCs) that survive many kinds of therapy. GSCs with high expression levels of CD44 are highly invasive and resistant to radio-chemotherapy. CD44 is a multifunctional molecule that promotes the invasion and proliferation of tumor cells via various signaling pathways. Among these, paired ...
Tópico(s): Cancer Cells and Metastasis
2023 - Multidisciplinary Digital Publishing Institute | Cancers
Yuhei Kawajiri, Sora-at Tanusilp, Masaya Kumagai, Manabu Ishimaru, Yuji Ohishi, Junya Tanaka, Ken Kurosaki,
A pair of n-type Bi2Te3–xSex and p-type (Bi,Sb)2Te3 is known as a promising candidate for assembling a high thermoelectric efficiency module operating at near room temperature. While the dimensionless figure of merit (zT) of p-type (Bi,Sb)2Te3 is commonly larger than 1.0, n-type Bi2Te3–xSex has a lower zT value of ∼0.8 at room temperature. Here, we aim to enhance the zT of n-type Bi2Te3–xSex through the energy filtering effect that can improve the Seebeck coefficient by adding Au. In the Bi2Te2.8Se0. ...
Tópico(s): Advanced Thermodynamics and Statistical Mechanics
2021 - American Chemical Society | ACS Applied Energy Materials
Mohammed E. Choudhury, Kazuya Miyanishi, Haruna Takeda, Junya Tanaka,
Poor sleep quality and disrupted circadian behavior are a normal part of aging and include excessive daytime sleepiness, increased sleep fragmentation, and decreased total sleep time and sleep quality. Although the neuronal decline underlying the cellular mechanism of poor sleep has been extensively investigated, brain function is not fully dependent on neurons. A recent antemortem autographic study and postmortem RNA sequencing and immunohistochemical studies on aged human brain have investigated ...
Tópico(s): Circadian rhythm and melatonin
2021 - Multidisciplinary Digital Publishing Institute | International Journal of Molecular Sciences
Mohammed E. Choudhury, Kanta Mikami, Yuiko Nakanishi, Taisei Matsuura, Ryo Utsunomiya, Hajime Yano, Madoka Kubo, Rina Ando, Jun Iwanami, Masakatsu Yamashita, Masahiro Nagai, Junya Tanaka,
Myeloid differentiation primary response gene 88 (MyD88) is essential for microglial activation. Despite the significant role of microglia in regulating sleep homeostasis, the contribution of MyD88 to sleep is yet to be determined. To address this, we performed electroencephalographic and electromyographic recordings on MyD88-KO mice and wild-type mice to investigate their sleep/wake cycles. In the daytime, MyD88-KO mice exhibited prolonged wakefulness and shorter non-rapid eye movement sleep duration. ...
Tópico(s): Circadian rhythm and melatonin
2021 - Elsevier BV | Journal of Neuroimmunology
Masahiro Nishikawa, Akihiro Inoue, Takanori Ohnishi, Hajime Yano, Saya Ozaki, Yonehiro Kanemura, Satoshi Suehiro, Yoshihiro Ohtsuka, Shohei Kohno, Shiro Ohue, Seiji Shigekawa, Hideaki Watanabe, Riko Kitazawa, Junya Tanaka, Takeharu Kunieda,
The poor prognosis of glioblastoma multiforme (GBM) is primarily due to highly invasive glioma stem-like cells (GSCs) in tumors. Upon GBM recurrence, GSCs with highly invasive and highly migratory activities must assume a less-motile state and proliferate to regenerate tumor mass. Elucidating the molecular mechanism underlying this transition from a highly invasive phenotype to a less-invasive, proliferative tumor could facilitate the identification of effective molecular targets for treating GBM. ...
Tópico(s): Cancer Research and Treatments
2021 - Elsevier BV | Translational Oncology