Photoluminescence characterization in silicon nanowire fabricated by thermal oxidation of nano-scale Si fin structure.

Low-temperature photoluminescence (PL) spectra of electron-hole systems in Si nanowires (NWs) prepared by thermal oxidization of Si fin structures were studied. Mapping of PL reveals that NWs with uniform width are formed over a large area. Annealing temperature dependence of PL peak intensities was maximized at 400 °C for each NW type, which are consistent with previous reports. Our results confirmed that the micro-PL demonstrated here is one of the important methods for characterizations of the interface defects in Si NWs.

Hyper-O-GlcNAcylation inhibits the induction of heat shock protein 70 (Hsp 70) by sodium arsenite in HeLa cells.

O-Linked ß-N-acetylglucosamine-modification (O-GlcNAcylation) is a reversible, post-translational, and regulatory modification of nuclear, mitochondrial, and cytoplasmic proteins that is responsive to cellular stress. However, the role of O-GlcNAcylation in the induction of heat shock proteins (Hsps) by arsenite remains unclear. We used O-(2-acetamido-2-deoxy-D-glucopyranosylidene) amino N-phenyl carbamate (PUGNAc), an inhibitor of O-GlcNAcase, and glucosamine (GlcN), an enhancer of the hexosamine biosynthesis pathway, or O-GlcNAc transferase (OGT) short interfering RNA (siRNA) to enhance or suppress cellular O-GlcNAcylation levels, respectively, in HeLa cells. The exposure to arsenite increased O-GlcNAcylation and Hsp 70 levels in HeLa cells. However, the pre-treatment with PUGNAc or GlcN, which enhanced O-GlcNAcylation levels, decreased the arsenite-induced expression of Hsp 70. The pre-treatment with OGT siRNA, which suppressed O-GlcNAcylation levels, did not affect the induction of Hsp 70. We then examined the effects of O-GlcNAcylation on the nuclear translocation and phosphorylation of heat shock factor 1 (HSF1), and found that neither the nuclear translocation nor phosphorylation of HSF1 was regulated by O-GlcNAcylation. Finally, Hsp 70 mRNA expression was induced by arsenite, whereas the addition of PUGNAc slightly suppressed its induction. These results indicate that O-GlcNAcylation is related to arsenite-induced Hsp 70 expression, and demonstrated that hyper-O-GlcNAcylation inhibited the induction of Hsp 70 via transcriptional factors instead of HSF1.

O-GlcNAc modification affects the ATM-mediated DNA damage response.

BACKGROUND: O-Linked ß-N-acetylglucosamine (O-GlcNAc) is a reversible, post-translational, and regulatory modification of nuclear, mitochondrial, and cytoplasmic proteins that is responsive to cellular stress. The role of O-GlcNAcylation in the ataxia-telangiectasia mutated (ATM)-mediated DNA damage response is unknown. It is unclear whether ATM, which is an early acting and central component of the signal transduction system activated by DNA double strand breaks, is an O-GlcNAc-modified protein. METHODS: The effect of O-GlcNAc modification on ATM activation was examined using two inhibitors, PUGNAc and DON that increase and decrease, respectively, levels of protein O-GlcNAcylation. To assess O-GlcNAcylation of ATM, immunoprecipitation and immunoblot analyses using anti-ATM or anti-O-GlcNAc antibody were performed in HeLa cells and primary cultured neurons. Interaction of ATM with O-GlcNAc transferase (OGT), the enzyme that adds O-GlcNAc to target proteins, was examined by immunoprecipitation and immunoblot analyses using anti-ATM. RESULTS: Enhancement of protein O-GlcNAcylation increased levels of X-irradiation-induced ATM activation. However, decreases in protein O-GlcNAcylation did not affect levels of ATM activation, but these decreases did delay ATM activation and ATM recovery processes based on assessment of de-phosphorylation of phospho-ATM. Thus, activation and recovery of ATM were affected by O-GlcNAcylation. ATM was subjected to O-GlcNAcylation, and ATM interacted with OGT. The steady-state O-GlcNAc level of ATM was not significantly responsive to X-irradiation or oxidative stress. GENERAL SIGNIFICANCE: ATM is an O-GlcNAc modified protein, and dynamic O-GlcNAc modification affects the ATM-mediated DNA damage response.

Case report: Presumptive subcutaneous malignant peripheral nerve sheath tumor with intracranial invasion and osteolysis in the posterior fossa of a dog.

A 13-year-old castrated male Toy Poodle presented with an acute vestibular disorder. Magnetic resonance imaging and computed tomography revealed a large oval space-occupying mass with skull destruction located from the subcutaneous tissue to the posterior fossa region. Histopathologically, the mass was a bundled growth of spindle-shaped mesenchymal tumor cells between the myofibrillar and collagen bundles. The cells were moderately irregular in size and had eosinophilic stained cytoplasm. The cells were highly atypical and had rare mitotic figures. Neoplastic cells were immunoreactive for S100, GFAP, Olig-2, SOX10 and immunonegative for NF, E-cadherin, and Claudin-1. Collective findings were presumptive with a diagnosis of malignant peripheral nerve sheath tumor.

Protective effect of N-glycan bisecting GlcNAc residues on beta-amyloid production in Alzheimer's disease.

Alteration of glycoprotein glycans often changes various properties of the target glycoprotein and contributes to a wide variety of diseases. Here, we focused on the N-glycans of amyloid precursor protein whose cleaved fragment, beta-amyloid, is thought to cause much of the pathology of Alzheimer's disease (AD). We previously determined the N-glycan structures of normal and mutant amyloid precursor proteins (the Swedish type and the London type). In comparison with normal amyloid precursor protein, mutant amyloid precursor proteins had higher contents of bisecting GlcNAc residues. Because N-acetylglucosaminyltransferase III (GnT-III) is the glycosyltransferase responsible for synthesizing a bisecting GlcNAc residue, the current report measured GnT-III mRNA expression levels in the brains of AD patients. Interestingly, GnT-III mRNA expression was increased in AD brains. Furthermore, beta-amyloid treatment increased GnT-III mRNA expression in Neuro2a mouse neuroblastoma cells. We then examined the influence of bisecting GlcNAc on the production of beta-amyloid. Both beta-amyloid 40 and beta-amyloid 42 were significantly decreased in GnT-III-transfected cells. When secretase activities were analyzed in GnT-III transfectant cells, alpha-secretase activity was increased. Taken together, these results suggest that upregulation of GnT-III in AD brains may represent an adaptive response to protect them from additional beta-amyloid production.

Translocation of lysosomal cathepsin D caused by oxidative stress or proteasome inhibition in primary cultured neurons and astrocytes.

We reported previously that N-linked glycoproteins were accumulated in the cytosol of the normal aging rat brain, and that one protein had been identified as cathepsin D (Mech. Ageing Dev., 127, 771-778 (2006)). In this study, to elucidate the mechanism of cathepsin D accumulation in the cytosol, we examined the effects of oxidative stress and proteasome inhibition on the apoptosis and subcellular localization of cathepsin D in primary cultured neurons and astrocytes. Using 4'-6-diamidino-2-phenylindole (DAPI)- or Hoechst 33342-staining and annexin V detection, we found that oxidative stress caused by tert-butyl hydroperoxide and proteasome inhibition by lactacystin induced apoptosis in neurons and astrocytes. Furthermore, after cell fractionation, it was demonstrated that cathepsin D was translocated from lysosomes to cytosol under apoptosis-inducing conditions in both cells. These results suggested that oxidative stress and the suppression of proteasome activity triggered the translocation of cathepsin D from lysosomes to cytosol. The possible mechanism of age-related accumulation of cathepsin D in the cytosol of the normal rat brain will be discussed.

Effects of erythropoietin on glial cell development; oligodendrocyte maturation and astrocyte proliferation.

We investigated the effects of erythropoietin (Epo) in glial cell development, especially the maturation of late stage immature oligodendrocytes and the proliferation of astrocytes. Epo mRNA level in oligodendrocytes was much more prominent than those in neurons or astrocytes, which were the same as those in the young adult kidney, while Epo receptor (Epo-R) mRNA level were almost the same among neural cells, kidney and liver tissues. On immunohistochemical examination, Epo-R expression was also detected in O4-positive immature oligodendrocytes and glial fibrillary acidic protein positive astrocytes. These results suggested that types of both glial cells are responsive to Epo. The numbers of mature oligodendrocytes, which are characterized by myelin basic protein and process development, were increased by treatment with recombinant human Epo (rhEpo) (0.001-0.1 U/ml). The maturation of oligodendrocytes was also enhanced by coculture with astrocytes in vitro. However, when mixed cultured cells (oligodendrocytes+astrocytes) were treated with anti-Epo antibody and/or soluble Epo-R, the differentiation of oligodendrocytes was partially inhibited. Interestingly, high dose rhEpo (1, 3, 10 U/ml) markedly enhanced the proliferation of astrocytes. These results suggested that Epo not only promotes the differentiation and/or maturation in oligodendrocytes, but also enhances the proliferation of astrocytes. It is generally accepted that astrocytes produce Epo, and therefore Epo might act on astrocytes in an autocrine manner. The astrocytes stimulated with Epo may further accelerate the maturation of oligodendrocytes. These comprehensive effects of Epo might also affect the ability of oligodendrocyte lineage cells to promote myelin repair in the normal and damaged adult central nervous system.

Effect of a traditional Chinese herbal medicine, Ren-Shen-Yang-Rong-Tang (Japanese name: Ninjin-Youei-To), on oligodendrocyte precursor cells from aged-rat brain.

Understanding of oligodendrocyte precursor cells and their role in the generation of oligodendrocytes in developing and adult rodents has been considered, particularly much less is known about aged-rodent oligodendrocyte precursor cells and their cell lineage. In this present study, we have developed oligodendrocyte cultures from the 30-month-old rat brain and examined whether oligodendrocyte precursor cells can proliferate in vitro. Adult oligodendrocyte precursor cells (O1(-), O4(+)) and oligodendrocytes (O1(+), O4(+)) are present in the cultures of the 30-month-old rat brain. They are also capable of proliferating and differentiating in the cultures. These capabilities increased four- to fivefold, when the aged rats are treated with Ninjin-Youei-To for 3 months in comparison with those of control aged rats. These results suggest that Ninjin-Youei-To has a potential mitotic effect on oligodendrocyte precursor cells in aged-rat brains and may be expected to have a therapeutic effect on brain aging.

Increased bisecting and core-fucosylated N-glycans on mutant human amyloid precursor proteins.

Alteration of glycoprotein glycans often changes various properties of the glycoprotein. To understand the significance of N-glycosylation in the pathogenesis of early-onset familial Alzheimer's disease (AD) and in beta-amyloid (Abeta) production, we examined whether the mutations in the amyloid precursor protein (APP) gene found in familial AD affect the N-glycans on APP. We purified the secreted forms of wild-type and mutant human APPs (both the Swedish type and the London type) produced by transfected C17 cells and determined the N-glycan structures of these three recombinant APPs. Although the major N-glycan species of the three APPs were similar, both mutant APPs contained higher contents of bisecting N-acetylglucosamine and core-fucose residues as compared to wild-type APP. These results demonstrate that familial AD mutations in the polypeptide backbone of APP can affect processing of the attached N-glycans; however, whether these changes in N-glycosylation affect Abeta production remains to be established.

Monoclonal antibody Rip specifically recognizes 2',3'-cyclic nucleotide 3'-phosphodiesterase in oligodendrocytes.

The antigen recognized with monoclonal antibody (mAb) Rip (Rip-antigen) has been long used as a marker of oligodendrocytes and myelin sheaths. However, the identity of Rip-antigen has yet to be elucidated. We herein identified the Rip-antigen. No signal recognized by mAb-Rip was detected by immunoblot analyses in the rat brain, cultured rat oligodendrocytes, or the oligodendrocyte cell line CG-4. As this antibody worked very well on immunocytochemistry and immunohistochemistry, Rip-antigen was immunopurified with mAb-Rip from the differentiated CG-4 cells. Eight strong-intensity bands thus appeared on 5-20% SDS-PAGE with SYPRO ruby fluorescence staining. To identify these molecules, each band extracted from the gel was analyzed by MALDI-QIT/TOF mass spectrometry. We found an interesting molecule in the oligodendrocytes from an approximately 44-kDa band as 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP). To test whether CNP was recognized by mAb-Rip, double-immunofluorescence staining was performed by using Alexa Fluor 488-conjugated mAb-Rip and Alexa Fluor 568-conjugated mAb-CNP in the rat cerebellum, mouse cerebellum, cultured rat oligodendrocytes, and CG-4 cells. The Rip-antigen was colocalized with CNP in these cells and tissues. To provide direct evidence that CNP was recognized by mAb-Rip, rat Cnp1-transfected HEK293T cells were used for double-immunofluorescence staining with mAb-Rip and mAb-CNP. The Rip-antigen was colocalized with CNP in rat Cnp1-transfected HEK293T cells, but the antigen was not detected by mAb-Rip and mAb-CNP in mock-transfected HEK293T cells. Overall, we have demonstrated that the antigen labeled with mAb-Rip is CNP in the oligodendrocytes.

Differentiation of immature oligodendrocytes is regulated by phosphorylation of cyclic AMP-response element binding protein by a protein kinase C signaling cascade.

Previous experiments showed that the expression and phosphorylation levels of cyclic AMP-response element binding protein (CREB) are important factors that regulate oligodendrocyte differentiation. The present study was designed to determine whether CREB phosphorylation advances oligodendrocyte differentiation or vice versa and to identify the protein kinase that primarily regulates CREB phosphorylation. We examined the expression and phosphorylation levels of CREB in developing oligodendrocytes at a specific differentiation stage by double-immunocytochemical staining with specific differentiation markers and antibody for phosphorylated CREB. We found that the CREB expression level increased along oligodendrocyte differentiation, and that its phosphorylated level was highest in immature oligodendrocytes. We also showed that CREB phosphorylation was regulated principally by protein kinase C (PKC) activity in immature oligodendrocytes. Our findings suggest that CREB phosphorylation is dependent on a PKC signaling cascade, and this phosphorylation activates CREB-mediated transcription and advances the differentiation of immature to mature oligodendrocytes.

Germin-like protein gene family of a moss, Physcomitrella patens, phylogenetically falls into two characteristic new clades.

We identified 77 EST clones encoding germin-like proteins (GLPs) from a moss, Physcomitrella patens in a database search. These Physcomitrella GLPs ( PpGLP s) were separated into seven groups based on DNA sequence homology. Phylogenetic analysis showed that these groups were divided into two novel clades clearly distinguishable from higher plant germins and GLPs, named bryophyte subfamilies 1 and 2. PpGLPs belonging to bryophyte subfamilies 1 lacked two cysteines at the conserved positions observed in higher plant germins or GLPs. PpGLPs belonging to bryophyte subfamily 2 contained two cysteines as observed in higher plant germins and GLPs. In bryophyte subfamily 1, 12 amino acids, in which one of two cysteines is included, were deleted between boxes A and B. Further, we determined the genomic structure of all of seven PpGLP genes. The sequences of PpGLP s of bryophyte subfamily 1 contained one or two introns, whereas those of bryophyte subfamily 2 contained no introns. Other GLPs from bryophytes, a liverwort GLP from Marchantia polymorpha , and two moss GLPs from Barbula unguiculata and Ceratodon purpureus also fell into bryophyte subfamily 1 and bryophyte subfamily 2, respectively. No higher plant germins and GLPs were grouped into the bryophyte subfamilies 1 and 2 by our analysis. Moreover, we revealed that PpGLP6 had manganese-containing extracellular superoxide dismutase activity. These results indicated that bryophyte possess characteristic GLPs, which phylogenetically are clearly distinguishable from higher plant GLPs.

Influence of cell density and thyroid hormone on glial cell development in primary cultures of embryonic rat cerebral hemisphere.

The influence of cell density and thyroid hormone (TH) on the development of astrocytes and oligodendrocytes was investigated in primary cultures prepared from rat cerebral hemisphere on embryonic day (E)18. At the beginning of the culture, most of the cells were microtubule-associated protein 2 (MAP2)-positive neurons, whereas O1-positive oligodendrocytes and glial fibrillary acidic protein (GFAP)-positive astrocytes were rarely observed. After the cells were maintained in serum-free defined medium, astrocytes developed at high cell density but rarely at a low one. When leukemia inhibitory factor (LIF) was supplemented in low-density cultures, the levels of GFAP expression markedly increased to almost the same extent as in high-density culture without TH. This suggests that, in low-density cultures, astrocyte progenitors could not differentiate because of insufficient astrocyte-inducing factors. Interestingly, the addition of TH increased GFAP expression levels only at high density. The number of oligodendrocytes increased with TH addition at both cell densities, although the effects were more remarkable at high density. These results suggest that cell density and TH are pivotal factors in the development of both astrocytes and oligodendrocytes. It is also suggested that the effects of TH on glial cell development could be accelerated via cell-cell communications.

Study of expression of myelin basic proteins (MBPs) in developing rat brain using a novel antibody reacting with four major isoforms of MBP.

Myelin basic proteins (MBPs) are the major protein components of myelin. MBP isoforms are known to have different expression patterns. In order to distinguish the different expression patterns on myelination, we have developed a novel antibody reacting with the four major isoforms of MBPs with molecular masses of 21.5 kDa, 18.5 kDa, 17.0 kDa, and 14.0 kDa. These MBPs were initially separated by acid urea gel and sodium dodecyl sulfate polyacrylamide gel electrophoreses and detected with the luminol reaction. Then the antibody developed was used to determine the relative amounts of MBP isoforms. The MBPs of oligodendrocytes were detected by the enhanced luminol reaction using Renaissance (Dupont NEN, Boston, MA). From the immunological aspect, the MBP monoclonal antibody (Sires et al. [1981] Science 214:87-89) was revealed to recognize MBPs with molecular masses of 21.5 kDa and 18.5 kDa. Furthermore, we found that Ile-166 in the rat 18.5-kDa MBP isomers was replaced by methionine. The 14.0-kDa and 18.5-kDa isoforms of MBP are the most abundant MBP species and comprise more than 70% of the total MBPs in 3.5-and 24-month-old rats. MBPs are expressed during development and the compositions of MBPs in mature (3.5 months old) and aged (24 months old) rats were almost the same. The expression of the 14.0-kDa and 18.5-kDa MBPs occurred earlier in the cerebellum and the spinal cord than in the cerebrum by approximately 1 week. MBPs are also expressed upon oligodendrocyte maturation by interacting with astrocytes. The above results suggest that the regulation of MBP isoforms during development and oligodendrocyte differentiation may indicate the point of occurrence of both the unique patterns of isoform expression and the shift in intracellular localization of MBPs with the maturation of oligodendrocytes.

Acute renal failure due to cholesterol crystal embolism treated with LDL apheresis followed by corticosteroid and candesartan.

Cholesterol crystal embolism (CCE) is caused by the shedding of cholesterol crystals into the bloodstream, and it has been recently recognized as a serious complication after vascular procedures. Our case of CCE, which was diagnosed by skin and renal biopsies, occurred in a patient with hypertension and diabetes mellitus, 3 months after coronary angiography, with the development of renal failure and blue toes. After low-density lipoprotein apheresis (LDL-A), the skin lesions, including livedo reticularis and pain from the acrocyanotic toes, dramatically improved, with partial recovery of renal function. Following the administration of low-dose corticosteroid and candesartan--an angiotensin II type 1 receptor antagonist (ARB)--the eosinophilia disappeared and renal function improved gradually with a decrease in urinary protein excretion. Therefore, a combination therapy of LDL-A, low-dose corticosteroid, and an ARB is a possible treatment for CCE, although the possibility of spontaneous recovery of renal function cannot be eliminated for this patient.