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1.
RSC Adv ; 9(32): 18353-18358, 2019 Jun 10.
Article in English | MEDLINE | ID: mdl-35515234

ABSTRACT

Purely organic crystals, κ-X3(Cat-EDT-TTF)2 [X = H or D, Cat-EDT-TTF = catechol-fused tetrathiafulvalene], are a new type of molecular conductor with hydrogen dynamics. In this work, hydrostatic pressure effects on these materials were investigated in terms of the electrical resistivity and crystal structure. The results indicate that the pressure induces and promotes hydrogen (deuterium) localization in the hydrogen bond, in contrast to the case of the conventional hydrogen-bonded materials (where pressure prevents hydrogen localization), and consequently leads to a significant change in the electrical conducting properties (i.e., the occurrence of a semiconductor-insulator transition). Therefore, we have successfully found a new type of pressure-induced phase transition where the cooperation of the hydrogen dynamics and π-electron interactions plays a crucial role.

2.
J Am Chem Soc ; 136(34): 12184-92, 2014 Aug 27.
Article in English | MEDLINE | ID: mdl-25127315

ABSTRACT

A hydrogen bond (H-bond) is one of the most fundamental and important noncovalent interactions in chemistry, biology, physics, and all other molecular sciences. Especially, the dynamics of a proton or a hydrogen atom in the H-bond has attracted increasing attention, because it plays a crucial role in (bio)chemical reactions and some physical properties, such as dielectricity and proton conductivity. Here we report unprecedented H-bond-dynamics-based switching of electrical conductivity and magnetism in a H-bonded purely organic conductor crystal, κ-D3(Cat-EDT-TTF)2 (abbreviated as κ-D). This novel crystal κ-D, a deuterated analogue of κ-H3(Cat-EDT-TTF)2 (abbreviated as κ-H), is composed only of a H-bonded molecular unit, in which two crystallographically equivalent catechol-fused ethylenedithiotetrathiafulvalene (Cat-EDT-TTF) skeletons with a +0.5 charge are linked by a symmetric anionic [O···D···O](-1)-type strong H-bond. Although the deuterated and parent hydrogen systems, κ-D and κ-H, are isostructural paramagnetic semiconductors with a dimer-Mott-type electronic structure at room temperature (space group: C2/c), only κ-D undergoes a phase transition at 185 K, to change to a nonmagnetic insulator with a charge-ordered electronic structure (space group: P1). The X-ray crystal structure analysis demonstrates that this dramatic switching of the electronic structure and physical properties originates from deuterium transfer or displacement within the H-bond accompanied by electron transfer between the Cat-EDT-TTF π-systems, proving that the H-bonded deuterium dynamics and the conducting TTF π-electron are cooperatively coupled. Furthermore, the reason why this unique phase transition occurs only in κ-D is qualitatively discussed in terms of the H/D isotope effect on the H-bond geometry and potential energy curve.


Subject(s)
Bridged Bicyclo Compounds, Heterocyclic/chemistry , Catechols/chemistry , Deuterium/chemistry , Electric Conductivity , Magnetic Phenomena , Semiconductors , Crystallization , Crystallography, X-Ray , Electron Transport , Hydrogen Bonding , Molecular Structure , Phase Transition , Spectrum Analysis, Raman
3.
PLoS One ; 7(11): e50391, 2012.
Article in English | MEDLINE | ID: mdl-23209732

ABSTRACT

BACKGROUND: Granulocyte colony-stimulating factor (G-CSF) is a protein that stimulates differentiation, proliferation, and survival of cells in the granulocytic lineage. Recently, a neuroprotective effect of G-CSF was reported in a model of cerebral infarction and we previously reported the same effect in studies of murine spinal cord injury (SCI). The aim of the present study was to elucidate the potential therapeutic effect of G-CSF for SCI in rats. METHODS: Adult female Sprague-Dawley rats were used in the present study. Contusive SCI was introduced using the Infinite Horizon Impactor (magnitude: 200 kilodyne). Recombinant human G-CSF (15.0 µg/kg) was administered by tail vein injection at 1 h after surgery and daily the next four days. The vehicle control rats received equal volumes of normal saline at the same time points. RESULTS: Using a contusive SCI model to examine the neuroprotective potential of G-CSF, we found that G-CSF suppressed the expression of pro-inflammatory cytokine (IL-1 beta and TNF- alpha) in mRNA and protein levels. Histological assessment with luxol fast blue staining revealed that the area of white matter spared in the injured spinal cord was significantly larger in G-CSF-treated rats. Immunohistochemical analysis showed that G-CSF promoted up-regulation of anti-apoptotic protein Bcl-Xl on oligpodendrocytes and suppressed apoptosis of oligodendrocytes after SCI. Moreover, administration of G-CSF promoted better functional recovery of hind limbs. CONCLUSIONS: G-CSF protects oligodendrocyte from SCI-induced cell death via the suppression of inflammatory cytokines and up-regulation of anti-apoptotic protein. As a result, G-CSF attenuates white matter loss and promotes hindlimb functional recovery.


Subject(s)
Granulocyte Colony-Stimulating Factor/metabolism , Oligodendroglia/cytology , Spinal Cord Injuries/metabolism , Animals , Apoptosis , Cerebral Infarction/metabolism , Female , Immunohistochemistry/methods , Inflammation , Interleukin-1beta/metabolism , Microscopy, Fluorescence/methods , Movement , Myelin Sheath/metabolism , Neurons/metabolism , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Spinal Cord/metabolism , Up-Regulation , bcl-X Protein/metabolism
4.
Neuropathology ; 31(1): 48-58, 2011 Feb.
Article in English | MEDLINE | ID: mdl-20573032

ABSTRACT

The aim of this study was to evaluate whether transplantation of human bone marrow stromal cell-derived Schwann cells (hBMSC-SC) promotes functional recovery after contusive spinal cord injury of adult rats. Human bone marrow stromal cells (hBMSC) were cultured from bone marrow of adult human patients and induced into Schwann cells (hBMSC-SC) in vitro. Schwann cell phenotype was confirmed by immunocytochemistry. Growth factors secreted from hBMSC-SC were detected using cytokine antibody array. Immunosuppressed rats were laminectomized and their spinal cords were contused using NYU impactor (10 g, 25 mm). Nine days after injury, a mixture of Matrigel and hBMSC-SC (hBMSC-SC group) was injected into the lesioned site. Five weeks after transplantation, cresyl-violet staining revealed that the area of cystic cavity was smaller in the hBMSC-SC group than that in the control group. Immunohistochemistry revealed that the number of anti-growth-associated protein-43-positive nerve fibers was significantly larger in the hBMSC-SC group than that in the control group. At the same time, the number of tyrosine hydroxylase- or serotonin-positive fibers was significantly larger at the lesion epicenter and caudal level in the hBMSC-SC group than that in the control group. In electron microscopy, formation of peripheral-type myelin was recognized near the lesion epicenter in the hBMSC-SC group. Hind limb function recovered significantly in the hBMSC-SC group compared with the control group. In conclusion, the functions of hBMSC-SC are comparable to original Schwann cells in rat spinal cord injury models, and are thus potentially useful treatments for patients with spinal cord injury.


Subject(s)
Recovery of Function , Schwann Cells/transplantation , Spinal Cord Injuries/pathology , Spinal Cord Injuries/surgery , Animals , Bone Marrow Cells/cytology , Bone Marrow Cells/metabolism , Bone Marrow Transplantation , Cell Differentiation , Cysts/pathology , Female , Humans , Immunohistochemistry , Male , Microscopy, Electron, Transmission , Nerve Regeneration/physiology , Rats , Rats, Wistar , Schwann Cells/metabolism , Schwann Cells/ultrastructure , Spinal Cord Injuries/metabolism , Stem Cells/cytology , Stem Cells/metabolism , Stromal Cells/cytology , Stromal Cells/metabolism , Young Adult
5.
Phys Rev Lett ; 102(17): 176403, 2009 May 01.
Article in English | MEDLINE | ID: mdl-19518803

ABSTRACT

We report on the experimental results of interlayer magnetoresistance in the multilayer massless Dirac fermion system alpha-(BEDT-TTF)2I3 under hydrostatic pressure and its interpretation. We succeeded in detecting the zero-mode Landau level (n=0 Landau level) that is expected to appear at the contact points of Dirac cones in the magnetic field normal to the two-dimensional plane. The characteristic feature of zero-mode Landau carriers including the Zeeman effect is clearly seen in the interlayer magnetoresistance.

6.
Acta Neuropathol ; 117(3): 321-8, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19125256

ABSTRACT

Macrophage migration inhibitory factor (MIF) is a multipotential protein that acts as a proinflammatory cytokine, a pituitary hormone, and a cell proliferation and migration factor. The objective of this study was to elucidate the role of MIF in spinal cord injury (SCI) using female MIF knockout (KO) mice. Mouse spinal cord compression injury was produced by application of a static load (T8 level, 20 g, 5 min). We analyzed the motor function of the hind limbs and performed histological examinations. Hind-limb function recovered significantly in the KO mice starting from three weeks after injury. Cresyl-violet staining revealed that the number of surviving neurons in the KO mice was significantly larger than that of WT mice six weeks after injury. Immunohistochemical analysis revealed that the number of NeuN/caspase-3-active, double-positive, apoptotic neurons in the KO mice was significantly smaller than that of the WT mice 24 and 72 h after SCI. These results were related to in-vitro studies showing increased resistance of cerebellar granular neurons from MIF-KO animals to glutamate neurotoxicity. These results suggest that MIF existence hinders neuronal survival after SCI. Suppression of MIF may attenuate detrimental secondary molecular responses of the injured spinal cord.


Subject(s)
Cell Death , Locomotion , Macrophage Migration-Inhibitory Factors/deficiency , Neurons/metabolism , Recovery of Function , Spinal Cord Injuries , Analysis of Variance , Animals , Caspase 3/metabolism , Cells, Cultured , Cerebellum/pathology , DNA-Binding Proteins , Extremities/physiopathology , Female , Glutamic Acid/toxicity , Immunohistochemistry , Macrophage Migration-Inhibitory Factors/genetics , Mice , Mice, Inbred BALB C , Mice, Knockout , Nerve Tissue Proteins/metabolism , Neurons/pathology , Nuclear Proteins/metabolism , Spinal Cord Compression/complications , Spinal Cord Injuries/etiology , Spinal Cord Injuries/pathology , Spinal Cord Injuries/physiopathology , Time Factors
7.
J Neurosurg Spine ; 9(6): 600-10, 2008 Dec.
Article in English | MEDLINE | ID: mdl-19035756

ABSTRACT

OBJECT: The authors previously reported that Schwann cells (SCs) could be derived from bone marrow stromal cells (BMSCs) in vitro and that they promoted axonal regeneration of completely transected rat spinal cords in vivo. The aim of the present study is to evaluate the efficacy of transplanted BMSC-derived SCs (BMSC-SCs) in a rat model of spinal cord contusion, which is relevant to clinical spinal cord injury. METHODS: Bone marrow stromal cells were cultured as plastic-adherent cells from the bone marrow of GFPtransgenic rats. The BMSC-SCs were derived from BMSCs in vitro with sequential treatment using beta-mercaptoethanol, all-trans-retinoic acid, forskolin, basic fibroblast growth factor, platelet derived-growth factor, and heregulin. Schwann cells were cultured from the sciatic nerve of neonatal, GFP-transgenic rats. Immunocytochemical analysis and the reverse transcriptase-polymerase chain reaction were performed to characterize the BMSC-SCs. For transplantation, contusions with the New York University impactor were delivered at T-9 in 10- to 11-week-old male Wistar rats. Four groups of rats received injections at the injury site 7 days postinjury: the first received BMSCSCs and matrigel, a second received peripheral SCs and matrigel, a third group received BMSCs and matrigel, and a fourth group received matrigel alone. Histological and immunohistochemical studies, electron microscopy, and functional assessments were performed to evaluate the therapeutic effects of BMSC-SC transplantation. RESULTS: Immunohistochemical analysis and reverse transcriptase-polymerase chain reaction revealed that BMSC-SCs have characteristics similar to SCs not only in their morphological characteristics but also in their immunocytochemical phenotype and genotype. Histological examination revealed that the area of the cystic cavity was significantly reduced in the BMSC-SC and SC groups compared with the control rats. Immunohistochemical analysis showed that transplanted BMSCs, BMSC-SCs, and SCs all maintained their original phenotypes. The BMSC-SC and SC groups had a larger number of tyrosine hydroxilase-positive fibers than the control group, and the BMSC-SC group had more serotonin-positive fibers than the BMSC or control group. The BMSC-SC group showed significantly better hindlimb functional recovery than in the BMSC and control group. Electron microscopy revealed that transplanted BMSC-SCs existed in association with the host axons. CONCLUSIONS: Based on their findings, the authors concluded that BMSC-SC transplantation reduces the size of the cystic cavity, promotes axonal regeneration and sparing, results in hindlimb functional recovery, and can be a useful tool for spinal cord injury as a substitute for SCs.


Subject(s)
Axons/physiology , Bone Marrow Transplantation/methods , Nerve Regeneration , Schwann Cells , Spinal Cord Injuries/therapy , Stromal Cells/cytology , Animals , Cell Differentiation , Male , Rats , Rats, Wistar , Recovery of Function , Spinal Cord Injuries/pathology , Spinal Cord Injuries/physiopathology , Thoracic Vertebrae
8.
Neurosci Lett ; 444(2): 143-7, 2008 Oct 24.
Article in English | MEDLINE | ID: mdl-18672025

ABSTRACT

Anoikis is a type of apoptosis due to the detachment from the extracellular matrix and neighboring cells. In case of cell transplantation therapy for spinal cord injury, preparation of graft cells includes dissociation of cultured cells, which may cause anoikis-induced cell death. Thus suppression of anoikis may increase survival of grafted cells. Here we tested the effect of brain-derived neurotrophic factor (BDNF) on anoikis-induced cell death of cultured Schwann cells. Schwann cells were collected and cultured from sciatic nerves of neonatal Wistar rats. Schwann cells were plated upon a non-adherent polyhydroxyethyl methacrylate substrate to induce anoikis. BDNF was added into the culture medium at various concentrations. Twenty-four hours after non-adherent culture, approximately 40% of Schwann cells died and BDNF significantly decreased the number of dead cells in that culture condition. Next, Schwann cells were transplanted with or without BDNF treatment into contused rat spinal cord 1 week after injury. Five weeks after transplantation, immunohistochemistry revealed that the number of transplanted cells was significantly larger in the BDNF-treated group than that of the non-treated group. Suppression of anoikis may increase survival of grafted cells in case of cell therapy for spinal cord injury.


Subject(s)
Anoikis , Brain-Derived Neurotrophic Factor/pharmacology , Schwann Cells/drug effects , Animals , Animals, Newborn , Cells, Cultured , Female , Immunohistochemistry , Rats , Rats, Wistar , Schwann Cells/physiology , Schwann Cells/transplantation , Sciatic Nerve/cytology , Spinal Cord Injuries/pathology , Spinal Cord Injuries/therapy
9.
J Neuropathol Exp Neurol ; 66(8): 724-31, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17882016

ABSTRACT

Granulocyte colony-stimulating factor (G-CSF) is a protein that stimulates differentiation, proliferation, and survival of granulocytic lineage cells. Recently, a neuroprotective effect of G-CSF was reported in a model of cerebral infarction. The aim of the present study was to elucidate the potential therapeutic effect of G-CSF for spinal cord injury (SCI) in mice. We found that G-CSF is neuroprotective against glutamate-induced cell death of cerebellar granule neurons in vitro. Moreover, we used a mouse model of compressive SCI to examine the neuroprotective potential of G-CSF in vivo. Histologic assessment with cresyl violet staining revealed that the number of surviving neurons in the injured spinal cord was significantly increased in G-CSF-treated mice. Immunohistochemistry for neuronal apoptosis revealed that G-CSF suppressed neuronal apoptosis after SCI. Moreover, administration of G-CSF promoted hindlimb functional recovery. Examination of signaling pathways downstream of the G-CSF receptor suggests that G-CSF might promote functional recovery by inhibiting neuronal apoptosis after SCI. G-CSF is currently used in the clinic for hematopoietic stimulation, and its ongoing clinical trial for brain infarction makes it an appealing molecule that could be rapidly placed into trials for patients with acute SCI.


Subject(s)
Granulocyte Colony-Stimulating Factor/therapeutic use , Neurons/drug effects , Recovery of Function/drug effects , Spinal Cord Injuries , Animals , Animals, Newborn , Behavior, Animal , Caspase 3/metabolism , Cell Death/drug effects , Cells, Cultured , Cerebellum/cytology , Dose-Response Relationship, Drug , Enzyme Inhibitors/pharmacology , Female , Granulocyte Colony-Stimulating Factor/pharmacology , Mice , Mice, Inbred BALB C , Neurons/physiology , Phosphopyruvate Hydratase/metabolism , RNA, Messenger/metabolism , Receptors, Granulocyte Colony-Stimulating Factor/genetics , Receptors, Granulocyte Colony-Stimulating Factor/metabolism , Reverse Transcriptase Polymerase Chain Reaction/methods , Spinal Cord Injuries/drug therapy , Spinal Cord Injuries/pathology , Spinal Cord Injuries/physiopathology , Statistics, Nonparametric , Time Factors
10.
Brain Res ; 1149: 223-31, 2007 May 29.
Article in English | MEDLINE | ID: mdl-17391650

ABSTRACT

The aim of the present study was to elucidate the effects of granulocyte colony-stimulating factor (G-CSF)-mediated mobilization of bone marrow-derived stem cells on the injured spinal cord. Bone marrow cells of green fluorescent protein (GFP) transgenic mice were transplanted into lethally irradiated C57BL/6 mice. Four weeks after bone marrow transplantation, spinal cord injury was produced by a static load (20 g, 5 min) at T8 level. G-CSF (200 microg/kg/day) was injected subcutaneously for 5 days. Immunohistochemistry for GFP and cell lineage markers was performed to evaluate G-CSF-mediated mobilization of bone marrow-derived cells into injured spinal cord. Hind limb locomotor recovery was assessed for 6 weeks. Immunohistochemistry revealed that G-CSF increased the number of GFP-positive cells in injured spinal cord, indicating that bone marrow-derived cells were mobilized and migrated into injured spinal cord. The numbers of double positive cells for GFP and glial markers were larger in the G-CSF treated mice than in the control mice. Luxol Fast Blue staining revealed that G-CSF promoted white matter sparing. G-CSF treated mice showed significant recovery of hind limb function compared to that of the control mice. In conclusion, G-CSF showed efficacy for spinal cord injury treatment through mobilization of bone marrow-derived cells.


Subject(s)
Bone Marrow Cells/metabolism , Bone Marrow Transplantation , Granulocyte Colony-Stimulating Factor/therapeutic use , Nerve Regeneration/physiology , Recovery of Function/physiology , Spinal Cord Injuries/therapy , Animals , Cell Movement/physiology , Granulocyte Colony-Stimulating Factor/metabolism , Immunohistochemistry , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Spinal Cord Compression/therapy
11.
Chemistry ; 13(6): 1872-81, 2007.
Article in English | MEDLINE | ID: mdl-17136783

ABSTRACT

The crystal architecture, magnetic properties, and thermodynamic properties of [n-butylferrocene][Ni(mnt)2] (1), [tert-butylferrocene][Ni(mnt)2] (2), [1,1'-diethylferrocene][Ni(mnt)2] (3), and [1,1'-diisopropylferrocene][Ni(mnt)2] (4) were investigated (mnt=maleonitriledithiolate). These complexes exhibit a unique supramolecular structure in which the ferrocenium cations constitute honeycomb-like assembled structures surrounding columns of the anions. For 1, the cations form a dimer through a very short intermolecular ferrocene-ferrocene distance of 3.28 A, which mediates an antiferromagnetic interaction with a singlet-triplet energy gap of 5 K. First-order phase transitions occur in 1-3 at 364, 361, and 350 K, respectively, accompanied by thermal hysteresis.

12.
J Neurosurg Spine ; 5(5): 424-33, 2006 Nov.
Article in English | MEDLINE | ID: mdl-17120892

ABSTRACT

OBJECT: The use of human umbilical cord blood (HUCB) cells has been reported to improve functional recovery in cases of central nervous system injuries such as stroke, traumatic brain injury, and spinal cord injury (SCI). The authors investigated the effects of hemopoietic stem cells that were derived from HUCB and transplanted into the injured spinal cords of rats. METHODS: One week after injury, an HUCB fraction enriched in CD34-positive cells was transplanted into the experimental group. In control animals, vehicle (Matrigel) was transplanted. Recovery of motor functions was assessed using the Basso-Beattie-Bresnahan Locomotor Scale, and immunohistochemical examinations were performed. Cells from HUCB that were CD34 positive improved functional recovery, reduced the area of the cystic cavity at the site of injury, increased the volume of residual white matter, and promoted the regeneration or sparing of axons in the injured spinal cord. Immunohistochemical examination revealed that transplanted CD34-positive cells survived in the host spinal cord for at least 3 weeks after transplantation but had disappeared by 5 weeks. The transplanted cells were not positive for neural markers, but they were positive for hemopoietic markers. There was no evidence of an immune reaction at the site of injury in either group. CONCLUSIONS: These results suggest that transplantation of a CD34-positive fraction from HUCB may have therapeutic effects for SCI. The results of this study provide important preclinical data regarding HUCB stem cell-based therapy for SCI.


Subject(s)
Cord Blood Stem Cell Transplantation , Hematopoietic Stem Cell Transplantation , Spinal Cord Injuries/therapy , Transplantation, Heterologous , Animals , Antigens, CD34/physiology , Disease Models, Animal , Hindlimb/physiopathology , Humans , Infant, Newborn , Male , Rats , Rats, Wistar , Recovery of Function/physiology , Spinal Cord Injuries/pathology , Spinal Cord Injuries/physiopathology
13.
Exp Neurol ; 200(2): 392-7, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16624299

ABSTRACT

Axonal regeneration in the central nervous system is blocked by many different growth inhibitory factors. Some of these inhibitors act on neurons by activating RhoA and Rho-kinase, an effector of RhoA. Several studies have shown that Rho-kinase inhibition immediately after spinal cord injury enhances axonal sprouting and functional recovery. In this study, we ask whether delayed treatment with Rho-kinase inhibitor is effective in promoting regeneration and functional recovery. We administered Fasudil, a Rho-kinase inhibitor, locally to the injury site 4 weeks or immediately after contusion of the thoracic spinal cord in rats. Although the immediate treatment significantly stimulated axonal sprouting and recovery of hindlimb function, treatment started 4 weeks after surgery had no effect on fiber sprouting or locomotor recovery. Our findings suggest that RhoA/Rho-kinase alone may not account for the irreversible arrest of axon outgrowth in the chronic stage of injury in the central nervous system.


Subject(s)
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/analogs & derivatives , Enzyme Inhibitors/administration & dosage , Nerve Regeneration/drug effects , Protein Serine-Threonine Kinases/antagonists & inhibitors , Recovery of Function/drug effects , Spinal Cord Injuries/drug therapy , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/administration & dosage , Animals , Behavior, Animal/drug effects , Biotin/analogs & derivatives , Dextrans , Disease Models, Animal , Drug Administration Schedule , Immunohistochemistry/methods , Intracellular Signaling Peptides and Proteins , Male , Motor Activity/drug effects , Pyramidal Tracts/drug effects , Pyramidal Tracts/pathology , Rats , Rats, Wistar , Statistics, Nonparametric , Time Factors , rho-Associated Kinases
14.
Inorg Chem ; 44(23): 8628-41, 2005 Nov 14.
Article in English | MEDLINE | ID: mdl-16271005

ABSTRACT

Charge-transfer salts of branched-alkyl biferrocenes, (1',1' ''-R2-1,1' '-biferrocene)[Ni(mnt)2] (1a, R = isopropyl; 2a, R = dineopentyl) and (1',1' ''-R2-1,1' '-biferrocene)2[Co(mnt)2]2 (1b, R = isopropyl; 2b, R = dineopentyl), were prepared. Their valence states were investigated using X-ray crystallography and Mössbauer spectroscopy. Complexes 1a and 1b show segregated-stack crystal structures that contain columns of acceptors, whereas structures of 2a and 2b, which contain bulky donors, are rather discrete. All of the complexes contain mixed-valent biferrocenium monocations. A two-step valence transition was found in complex 1a. The crystal contains two crystallographically independent cations: one undergoes valence localization below room temperature; the other undergoes valence localization below ca. 130 K. The former transition is derived from asymmetry of the crystal environment around the cation, whereas the latter one is caused by symmetry lowering coupled with a spin-Peierls transition (T(C) = 133.2 K) associated with the dimerization of the acceptors. This compound was found to exhibit a dielectric response based on valence tautomerization. Other complexes (1b, 2a, and 2b) show a valence-trapped state. In all complexes, charge localization was found to occur through local electrostatic interactions between the donor's cationic moiety and the acceptor's electronegative moieties.

15.
Neuroreport ; 16(16): 1763-7, 2005 Nov 07.
Article in English | MEDLINE | ID: mdl-16237323

ABSTRACT

We compared the effects of hematopoietic stem cell and marrow stromal cell transplantation for spinal cord injury in mice. From green fluorescent protein transgenic mouse bone marrow, lineage-negative, c-kit- and Sca-1-positive cells were sorted as hematopoietic stem cells and plastic-adherent cells were cultured as marrow stromal cells. One week after injury, hematopoietic stem cells or marrow stromal cells were injected into the lesioned site. Functional recovery was assessed and immunohistochemistry was performed. In the hematopoietic stem cell group, a portion of green fluorescent protein-positive cells expressed glial marker. In the marrow stem cell group, a number of green fluorescent protein and fibronectin-double positive cells were observed. No significant difference was observed in the recovery between both groups. Both hematopoietic stem cells and marrow stromal cells have the potential to restore the injured spinal cord and to promote functional recovery.


Subject(s)
Bone Marrow Cells/physiology , Bone Marrow Transplantation/methods , Hematopoietic Stem Cell Transplantation/methods , Hematopoietic Stem Cells/physiology , Spinal Cord Injuries/surgery , Adenomatous Polyposis Coli Protein/metabolism , Animals , Disease Models, Animal , Female , Fibronectins/metabolism , Flow Cytometry/methods , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Immunohistochemistry/methods , Leukocyte Common Antigens/metabolism , Mice , Mice, Inbred C57BL , Mice, Transgenic , Time Factors
16.
J Neuropathol Exp Neurol ; 64(1): 37-45, 2005 Jan.
Article in English | MEDLINE | ID: mdl-15715083

ABSTRACT

The aim of this study was to evaluate whether transplantation of Schwann cells derived from bone marrow stromal cells (BMSC-SCs) promotes axonal regeneration and functional recovery in completely transected spinal cord in adult rats. Bone marrow stromal cells (BMSCs) were induced to differentiate into Schwann cells in vitro. A 4-mm segment of rat spinal cord was removed completely at the T7 level. An ultra-filtration membrane tube, filled with a mixture of Matrigel (MG) and BMSC-SCs (BMSC-SC group) or Matrigel alone (MG group), was grafted into the gap. In the BMSC-SC group, the number of neurofilament- and tyrosine hydroxylase-immunoreactive nerve fibers was significantly higher compared to the MG group, although 5-hydroxytryptamine- or calcitonin gene-related peptide-immunoreactive fibers were rarely detectable in both groups. In the BMSC-SC group, significant recovery of the hindlimb function was recognized, which was abolished by retransection of the graft 6 weeks after transplantation. These results demonstrate that transplantation of BMSC-SCs promotes axonal regeneration of lesioned spinal cord, resulting in recovery of hindlimb function in rats. Transplantation of BMSC-SCs is a potentially useful treatment for spinal cord injury.


Subject(s)
Axons/transplantation , Bone Marrow Transplantation/methods , Nerve Regeneration/physiology , Recovery of Function/physiology , Schwann Cells/transplantation , Spinal Cord Injuries/physiopathology , Animals , Immunohistochemistry , Male , Motor Activity/physiology , Rats , Rats, Wistar , Schwann Cells/cytology , Spinal Cord Injuries/metabolism , Spinal Cord Injuries/pathology , Stromal Cells/cytology , Stromal Cells/transplantation , Thoracic Vertebrae/innervation , Thoracic Vertebrae/surgery , Time Factors
17.
Chem Commun (Camb) ; (21): 2454-5, 2004 Nov 07.
Article in English | MEDLINE | ID: mdl-15514812

ABSTRACT

A newly synthesized donor meso-DMBEDT-TTF [DMBEDT-TTF = 2-(5,6-dihydro-1,3-dithiolo[4,5-b][1,4]dithiin-2-ylidene)-5,6-dihydro-5,6-dimethyl-1,3-dithiolo[4,5-b][1,4]dithiin] afforded a superconducting salt beta-(meso-DMBEDT-TTF)2PF6, with a transition temperature at 4.3 K (onset) under a hydrostatic pressure of 4.0 kbar.


Subject(s)
Electric Conductivity , Heterocyclic Compounds, 2-Ring/chemistry , Sulfhydryl Compounds/chemistry , Crystallography, X-Ray , Models, Molecular , Molecular Structure , Temperature
18.
Acta Neuropathol ; 108(1): 31-6, 2004 Jul.
Article in English | MEDLINE | ID: mdl-15067555

ABSTRACT

Macrophage migration inhibitory factor (MIF) is a multipotential protein that acts as a pro-inflammatory cytokine, pituitary hormone, immunoregulator, and mitogen. To elucidate function of MIF in spinal cord injury, we examined expression of MIF after compression-induced spinal cord injury using Northern blot analysis, in situ hybridization and immunohistochemistry. The MIF mRNA was up-regulated in injured spinal cord, peaking 3 days after injury shown by Northern blot analysis. In situ hybridization revealed up-regulation of MIF in microglia accumulating in the lesion epicenter 3 days after injury and astrocytes around the cystic cavity 1 week after injury. Double staining showed co-localization of MIF and tomato lectin in the lesioned site, indicating that microglia accumulating to the lesion epicenter express MIF. The time course of MIF expression is different from that of previous reports about cytokine expression peaking at earlier time points; thus, it is unlikely that MIF acts as a pro-inflammatory factor in the present study. The MIF may contribute to proliferation of astrocytes around the lesioned site in spinal cord injury because of its cell proliferation-promoting property.


Subject(s)
Gene Expression Regulation/physiology , Macrophage Migration-Inhibitory Factors/metabolism , Spinal Cord Compression/metabolism , Spinal Cord Injuries/metabolism , Up-Regulation/physiology , Animals , Blotting, Northern/methods , Cell Count/methods , Immunohistochemistry/methods , In Situ Hybridization/methods , Macrophage Migration-Inhibitory Factors/genetics , Male , Microglia/metabolism , Plant Lectins/metabolism , RNA, Messenger/metabolism , Rats , Rats, Wistar , Reverse Transcriptase Polymerase Chain Reaction/methods , Spinal Cord Compression/complications , Spinal Cord Injuries/etiology , Time Factors
19.
J Am Chem Soc ; 124(7): 1251-60, 2002 Feb 20.
Article in English | MEDLINE | ID: mdl-11841294

ABSTRACT

The systematic study of band-filling control for four kinds of organic conductors with various kinds of ground states has succeeded. (1) By partial substitution of (GaCl(4))(-) by (MCl(4))(2-) [M = Co, Zn] in the anion blocking layer of lambda-ET(2)(GaCl(4))(-) [ET = bis(ethylenedithio)tetrathiafulvalene], single crystals of lambda-ET(2)(GaCl(4))(-)(1-x)(MCl(4))(2-)(x) [x = 0.0, 0.05, 0.06] have been obtained. The resistivity at room temperature decreases from 3 Omega cm (x = 0.0) to 0.1 Omega cm (x = 0.06) by doping to the antiferromagnet with an effective half-filled band (x = 0.0). (2) Another 2:1 (donor/anion) salt, delta'-ET(2)(GaCl(4))(-), which is a spin gap material, has been doped as delta'-ET(2)(GaCl(4))(-)(1-x)(MCl(4))(2-)(x) [x = 0.05, 0.14]. The resistivity is lowered from 10 Omega cm (x = 0.0) to 0.3 Omega cm (x = 0.14). For both 2:1 salts, the semiconducting behaviors have transferred to relatively conductive semiconducting ones by doping. (3) As for alpha-type 3:1 salts, the parent material is in a charge-ordering state such as alpha-(ET(+)ET(+)ET(0))(CoCl(4))(2-)(TCE), where the charge-ordered donors are dispersed in the two-dimensional conducting layer. Although the calculation of alpha-ET(3)(CoCl(4))(2-)(TCE) shows a band-insulating nature, and the crystal structure analysis indicates that this material is in a charge-ordering state, the metallic behavior down to 165 K has been observed. With doping of (GaCl(4))(-) to the alpha-system, isostructural alpha-ET(3)(CoCl(4))(2-)(1-x)(GaCl(4))(-)(x)(TCE) [x = 0.54, 0.57, 0.62] have been afforded, where the pattern of the horizontal stripe-type charge ordering changes with an increase of x. (4) By doping (GaCl(4))(-) to the 3:2 gapless band insulator which is isostructural to beta'-ET(3)(MCl(4))(2)(2-) [M = Zn, Mn], the obtained beta'-ET(3)(CoCl(4))(2-)(2-x)(GaCl(4))(-)(x) [x = 0.66, 0.88] shows metallic behavior down to 100 and 140 K, respectively. They are the first metallic states in organic conductors by band-filling control of the gapless band insulator. These systematic studies of band-filling control suggest that the doping to the gapless band insulator with a pseudo-1/2-filled band is most effective.

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