Development of a Gallium-doped Germanium Far-infrared Photoconductor Direct Hybrid Two-dimensional Array

Applied Optics. Apr, 2003  |  Pubmed ID: 12716158

To our knowledge, we are the first to successfully report a direct hybrid two-dimensional (2D) detector array in the far-infrared region. Gallium-doped germanium (Ge:Ga) has been used extensively to produce sensitive far-infrared detectors with a cutoff wavelength of approximately equal to 110 microm (2.7 THz). It is widely used in the fields of astronomy and molecular and solid spectroscopy. However, Ge:Ga photoconductors must be cooled below 4.2 K to reduce thermal noise, and this operating condition makes it difficult to develop a large format array because of the need for a warm amplifier. Development of Ge:Ga photoconductor arrays to take 2D terahertz images is now an important target in such research fields as space astronomy. We present the design of a 20 x 3 Ge:Ga far-infrared photoconductor array directly hybridized to a Si p-type metal-oxide-semiconductor readout integrated circuit using indium-bump technology. The main obstacles in creating this 2D array were (1) fabricating a monolithic Ge:Ga 2D array with a longitudinal configuration, (2) developing a cryogenic capacitive transimpedance amplifer, and (3) developing a technology for connecting the detector to the electronics. With this technology, a prototype Ge:Ga photoconductor with a direct hybrid structure has shown a responsivity as high as 14.6 A/W and a minimum detectable power of 5.6 x 10(-17) W for an integration time of 0.14 s when it was cooled to 2.1 K. Its noise is limited by the readout circuit with 20 microV/Hz(1/2) at 1 Hz. Vibration and cooling tests demonstrated that this direct hybrid structure is strong enough for spaceborne instruments. This detector array will be installed on the Japanese infrared satellite ASTRO-F.

Odorant Response Assays for a Heterologously Expressed Olfactory Receptor

Biochemical and Biophysical Research Communications. Jun, 2003  |  Pubmed ID: 12767924

Odorant responsiveness of a mouse olfactory receptor, mOR-EG, was investigated in various heterologous cells using a variety of detection methods. Odorant-induced Ca(2+) response was observed in HEK293 cells that coexpressed mOR-EG and the promiscuous G protein, G alpha 15. Without G alpha 15, a robust increase in cAMP level was observed upon odorant-stimulation in various mammalian cells. A luciferase reporter gene assay using zif268 promoter was adopted to amplify the cAMP signals. In Xenopus laevis oocytes, odorant-stimulated currents were recorded when mOR-EG cRNA was co-injected with either G alpha 15 or cAMP-dependent channel. These results suggest that odorant responsiveness can be monitored via a signaling pathway mediated by endogenous G alphas or transfected G alpha 15 in heterologous cell systems. Various functional assays for a heterologously expressed olfactory receptor reported in this study, are potentially useful for high-throughput ligand screening and functional analyses of hundreds of olfactory receptors.

Gene Expression Patterns in in Vivo Normal Adult Astrocytes Compared with Cultured Neonatal and Normal Adult Astrocytes

Neurochemistry International. Jul-Aug, 2004  |  Pubmed ID: 15145538

This paper presents data on the basal gene expression patterns, determined by microarray analysis, for cultured neonatal and normal adult striatal astrocytes, and for comparison, for astrocytes isolated directly from adult rat striatum (in vivo adult astrocytes). Of the 1176 genes on the Clontech array, 1101 were expressed in one of the three types of astrocyte samples. Nineteen of the genes were expressed only in the astrocytes taken directly from adult rats (in vivo adult). The cultured neonatal astrocytes expressed many genes at a two-fold or greater level than their expression in cultured adult astrocytes, including genes in the adhesion, cytoskeleton, and extracellular matrix (ECM) family, signal transduction genes, and genes related to apoptosis, DNA-binding, and cell cycle regulation. Overall the results support the concept that cultured neonatal astrocytes are more "activated" than cultured adult cells, although the adult cells expressed higher levels of many metabolic enzyme and protease/protease inhibitor genes.

Gene Expression Profiles of Reactive Astrocytes in Dopamine-depleted Striatum

Brain Pathology (Zurich, Switzerland). Jul, 2004  |  Pubmed ID: 15446582

We have used cDNA array analysis to examine the expression of genes in reactive astrocytes of dopamine-depleted striatum of rats in vivo, an animal model for Parkinson disease, compared to those from control striatum. The striatum of both normal adult rats and rats whose substantia nigra had been lesioned with 6-hydroxydopamine was removed one week following lesion. After fixing the tissue in RNAlater, individual astrocytes, isolated directly from dissociated striatum and confirmed to be astocytes by expression of glial fibrillary acidic protein (GFAP) mRNA using single cell RT-PCR, were used as the source of mRNA. Co-localization of GFAP with either of 2 antibodies known to label only reactive astrocytes in vivo confirmed that virtually all astrocytes in the lesioned striatum were reactive. The analysis has identified 29 genes whose expression is turned on or enhanced in dopamine-depleted striatal astrocytes and 2 whose expression is decreased. In situ hybridization was used to confirm the localization of 8 of these genes to astrocytes: these included GDNF, NGF, bFGF, TNF-alpha, MIP-1alpha, c-jun, Fra-1 and Fra-2. Understanding these gene differences that occur in astrocytes in response to dopamine depletion should enhance our ability to promote recovery from the injury.

Endoscopic Hemostasis Using Fibrin Adhesive to Treat Hemorrhage in the Upper Digestive System

Surgery Today. 2004  |  Pubmed ID: 15526123

There are several methods of achieving endoscopic hemostasis of hemorrhage in the upper digestive system. We compared the therapeutic results and advantages of using a local injection of fibrin adhesive for endoscopic hemostasis, which we have found more effective than other hemostatic methods.

Identification and Functional Characterization of a Sex Pheromone Receptor in the Silkmoth Bombyx Mori

Proceedings of the National Academy of Sciences of the United States of America. Nov, 2004  |  Pubmed ID: 15545611

Sex pheromones released by female moths are detected with high specificity and sensitivity in the olfactory sensilla of antennae of conspecific males. Bombykol in the silkmoth Bombyx mori was the first sex pheromone to be identified. Here we identify a male-specific G protein-coupled olfactory receptor gene, B. mori olfactory receptor 1 (BmOR-1), that appears to encode a bombykol receptor. The BmOR-1 gene is located on the Z sex chromosome, has an eight-exon/seven-intron structure, and exhibits male-specific expression in the pheromone receptor neurons of male moth antenna during late pupal and adult stages. Bombykol stimulation of Xenopus laevis oocytes expressing BmOR-1 and BmGalphaq elicited robust dose-dependent inward currents on two-electrode voltage clamp recordings, demonstrating that the binding of bombykol to BmOR-1 leads to the activation of a BmGalphaq-mediated signaling cascade. Antennae of female moths infected with BmOR-1-recombinant baculovirus showed electrophysiological responses to bombykol but not to bombykal. These results provide evidence that BmOR-1 is a G protein-coupled sex pheromone receptor that recognizes bombykol.

Insect Sex-pheromone Signals Mediated by Specific Combinations of Olfactory Receptors

Science (New York, N.Y.). Mar, 2005  |  Pubmed ID: 15692016

We describe two male-specific olfactory receptors (ORs) in the silk moth, Bombyx mori, that are mutually exclusively expressed in a pair of adjacent pheromone-sensitive neurons of male antennae: One is specifically tuned to bombykol, the sex pheromone, and the other to bombykal, its oxidized form. Both pheromone ORs are coexpressed with an OR from the highly conserved insect OR subfamily. This coexpression promotes the functional expression of pheromone receptors and confers ligand-stimulated nonselective cation channel activity. The same effects were also observed for general ORs. Both odorant and pheromone signaling pathways are mediated by means of a common mechanism in insects.

Glioma Cells Under Hypoxic Conditions Block the Brain Microvascular Endothelial Cell Death Induced by Serum Starvation

Journal of Neurochemistry. Oct, 2005  |  Pubmed ID: 16042757

Angiogenesis is one of essential components for the growth of neoplasms, including malignant gliomas. However, tumor vascularization is often poorly organized and marginally functional due to tumor structural abnormalities, inducing regional or temporal hypoxic conditions and nutritional shortages in tumor tissues. We investigated how during angiogenesis migrating endothelial cells survive in these hypoxic and reduced nutritional conditions. Human brain microvascular endothelial cells (HBMECs) underwent apoptosis and necrosis after serum withdrawal. This endothelial cell death was blocked by recombinant VEGF protein or the culture medium of U251 glioma cells exposed to hypoxia (H-CM). Hypoxic treatment increased vascular endothelial growth factor (VEGF) and tumor necrosis factor alpha (TNF-alpha) expression in U251 glioma cells. H-CM activated nuclear factor-kappaB (NFkappaB) protein and increased the gene expression of antiapoptotic factors including Bcl-2, Bcl-X(L), survivin and X-chromosome-linked inhibitor of apoptosis protein (XIAP) in endothelial cells. The survival activity of H-CM for endothelial cells was abolished by two kinds of VEGF inhibitors {Cyclopeptidic VEGF inhibitor and a VEGF receptor tyrosine kinase inhibitor (4-[(4'-chloro-2'-fluoro) phenylamino]-6, 7-dimethoxyquinazoline)} or NFkappaB inhibitors (ALLN and BAY 11-7082). These VEGF inhibitors did not block the activation of NFkappaB induced by H-CM in endothelial cells. On the contrary, TNF-alpha antagonist WP9QY enhanced the survival activity of H-CM for endothelial cells and blocked NFkappaB activation induced by H-CM under serum-starved conditions. Taken together, our data suggest that both the secretion of VEGF from glioma cells and activation of NFkappaB in endothelial cells induced by TNF-alpha are necessary for endothelial cell survival as they increase the expression of antiapoptotic genes in endothelial cells under conditions of serum starvation. These pathways may be one of the mechanisms by which angiogenesis is maintained in glioma tissues.

Case with Bromine Exposure Leading to Respiratory Insufficiency

Chūdoku Kenkyū : Chūdoku Kenkyūkai Jun Kikanshi = The Japanese Journal of Toxicology. Apr, 2005  |  Pubmed ID: 16045175

A 21-year-old male had a chemical burn on the right forearm when he inadvertently spilled bromine during an experiment. Since he inhaled vaporized bromine and had dyspnea and pharyngalgia, he arrived at our hospital in an ambulance as an emergency patient. On arrival, he kept a clear consciousness with a pulse rate of 98, body temperature of 36.8 degrees C, blood pressure of 132/80 mmHg, respiratory rate of 25, and oxygen saturation of 100%. (10 L/min of oxygen were administered.) He had marked dry coughs. His clothes had a foreign odor with mucosal irritation. Arterial blood gas analysis and blood biochemistry were normal. Based on these findings, he was diagnosed with chemical airway damage and bulbar conjunctiva from the exposure to bromine and a chemical burn on the right forearm. His respiratory condition became worse after admission, resulting in pulmonary edema. He was endotracheally intubated and controlled with an artificial ventilator on Day 3 after his injury. He was continuously treated with steroids and sivelestat sodium hydrate, which gradually improved his respiration. He was released from the artificial ventilator and extubated on Day 7. Although dyspnea associated with body movement and hoarseness persisted after extubation, the symptoms decreased and he was discharged on Day 41. This rare case is worth attention because serious respiratory insufficiency requiring artificial ventilation due to pulmonary edema from bromine exposure has not been reported in Japan.

[Molecular Mechanisms Underlying Sex-pheromone Reception in Insects]

Tanpakushitsu Kakusan Koso. Protein, Nucleic Acid, Enzyme. Oct, 2005  |  Pubmed ID: 16218457

Gene Expression Profiles of Reactive Astrocytes Cultured from Dopamine-depleted Striatum

Neurobiology of Disease. Nov, 2005  |  Pubmed ID: 16242635

We have carried out cDNA array analysis in order to characterize the gene expression profiles of reactive astrocytes from dopamine-depleted striatum. Astrocytes were cultured from the striatum of normal adult rats (adult astrocytes) or adult rats in which the substantia nigra had been lesioned 1 week earlier with 6-hydroxydopamine (reactive astrocytes), an animal model for Parkinson's disease. Three antibodies, 19D1, O1E4, and 13A11, known to label only reactive astrocytes in vivo, stained cultured reactive astrocytes but not adult astrocytes. Analysis with cDNA arrays showed that 38 genes were up-regulated and 75 genes down-regulated in reactive astrocytes compared to normal adult astrocytes. The expression of growth factor and transcription factor genes predominated among the up-regulated genes while those for signal transduction molecules, metabolic enzymes, and receptors for growth factors, hormones, and neurotransmitters predominated among the down-regulated genes. These results will allow the field to address the molecular profiles and functions of astrocytes activated in response to dopamine depletion and may be useful for developing new therapies for Parkinson's disease.

Cryogenic Optical Performance of the ASTRO-F SiC Telescope

Applied Optics. Nov, 2005  |  Pubmed ID: 16294954

The lightweight cryogenic telescope on board the Japanese infrared astronomical satellite, ASTRO-F, which is scheduled to be launched early in 2006, forms an F/6 Ritchey-Chretien system with a primary mirror of 710 mm in diameter. The mirrors of the ASTRO-F telescope are made of sandwich-type silicon carbide (SiC) material, comprising a porous core and a chemical-vapor-deposited coat of SiC on the surface. To estimate the optical performance of the flight model telescope, the telescope assembly was tested at cryogenic temperatures, the total wavefront errors of which were measured by an interferometer from outside a liquid-helium chamber. As a result, the wavefront error obtained at 9 K shows that the imaging performance of the ASTRO-F telescope is diffraction limited at a wavelength of 6.2 microm, which is a little worse than our original goal of diffraction-limited performance at 5.0 microm.

Acquisition of Resistance to Antitumor Alkylating Agent ACNU: a Possible Target of Positron Emission Tomography Monitoring

Nuclear Medicine and Biology. Jan, 2006  |  Pubmed ID: 16459256

Early detection of tumor response to chemotherapy is of great importance for appropriate treatment of tumors. In this study, characteristics of two positron emission tomography (PET) tracers, [(18)F]2-fluoro-2-deoxy-D-glucose (FDG) and[(18)F]3'-fluoro-3'-deoxy-thymidine (FLT), in the early detection of tumor cell response as well as tolerance development to chemotherapy was compared using rat C6 glioma cells and 1-(4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl)-3-nitrosoureahydrochloride (ACNU). ACNU is an alkylating agent known to induce drug resistance through expression of O(6)-methylguanine-deoxyribonucleic acid methyl transferase (O(6)-MGMT). We established an ACNU-resistant C6 glioma cell line (C6/ACNU) and investigated the effect of ACNU on the uptake of FLT and FDG. In C6 cells, DNA synthesis presented as [(3)H]thymidine ([(3)H]Thd) incorporation into DNA was quickly suppressed by ACNU. In C6/ACNU cells, the suppression was recovered promptly, indicating that DNA alkylation occurs initially but highly expressed O(6)-MGMT repairs DNA, leading to the recovery of DNA synthesis. The patterns of FLT uptake in C6 and C6/ACNU were difficult to distinguish in the very early stage of the treatment, though it was reported that FLT uptake well correlated with proliferation in certain conditions. FDG uptake showed different patterns between the resistant and control cells, with significantly decreased uptake in C6 cells and unchanged uptake in C6/ACNU cells at 18-24 h after the treatment. Though difficult to be directly translated into clinical situation, the present study will provide a base to develop an appropriate protocol to assess tumor response to treatment by PET and to design effective treatment plans.

Astroblastoma: Immunohistochemical and Ultrastructural Study of Distinctive Epithelial and Probable Tanycytic Differentiation

Neuropathology : Official Journal of the Japanese Society of Neuropathology. Feb, 2006  |  Pubmed ID: 16521483

We report the clinicopathological findings of astroblastoma found in an 8-year-old girl who was subsequently treated for 11 years. The primary superficially circumscribed tumor was located in the frontoparietal lobe, while the recurrent and the second recurrent tumor were restricted to the same region 11 years later. The tumors obtained on these three occasions showed fundamentally the same histological, immunohistochemical and fine structural features. They exhibited astrocytic as well as ependymal tanycytic features with apparent epithelial cell lineage. The tumor cells showed typical features of astroblastoma comprising prominent perivascular pseudorosettes with remarkable vascular sclerosis. The immunohistochemical study revealed intensive positivity of GFAP, vimentin, epithelial membrane antigen (EMA), cytokeratin, connexin 26 and 32, desmocollin 1 and neuronal cadherin. The fine structure revealed divergent types of junctional complexes, some of which were connected with tonofilament bundles. Numerous microvilli protruded and basal lamina abutted on the tumor cell surface. We report these unique histological features, and stress that astroblastoma should be categorized as a specific type of neuroepithelial tumor.

Gene Expression Profiles of 1-(4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU)-resistant C6 Rat Glioma Cells

Journal of Neuro-oncology. Sep, 2006  |  Pubmed ID: 16645721

Chemotherapy in itself is suspected to cause the development or selection of drug-resistant tumor cells, which have more aggressive phenotypes. The authors investigated the differential changes of gene expression in the 1-(4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU)-resistant subline of the C6 rat glioma (C6AR2), which was established from C6 rat glioma cells by exposure to ACNU in vitro. The resistance to ACNU of C6AR2 was confirmed by MTS assay. The increased expression of O6-methylguanine-DNA methyltransferase in C6AR2 cells was shown using RT-PCR. C6AR2 cells displayed a higher proliferative activity relative to C6 cells. Analysis with cDNA array showed that 19 genes were transcriptionally up-regulated and 16 genes down-regulated in C6AR2 cells compared to C6 cells. They belonged to various functional classes of genes beside the drug-resistant system. Among them, the down-regulation of several genes in C6AR2 cells, including c-kit, pleiotrophin, platelet-derived growth factor receptor-alpha, peripheral myelin protein-22 and NG2 chondroitin sulfate proteoglycan, which are expressed originally in developmental glial lineages, were verified using semi-quantitative RT-PCR. In addition, the gene expression of astroglial intermediate filament proteins, including GFAP, vimentin and nestin, were decreased in C6AR2 cells relative to C6 cells in semi-quantitative RT-PCR and immunocytochemistry. These findings may represent an undifferentiated state of ACNU-resistant glioma cells and a more aggressive phenotype in recurrent tumors following chemotherapy.

Neuronal Loss and Expression of Neurotrophic Factors in a Model of Rat Chronic Compressive Spinal Cord Injury

Spine. Aug, 2006  |  Pubmed ID: 16915089

An experimental animal study about neuronal loss and the expression of neurotrophic factors in the chronic compressive spinal cords.

Reinforcement Therapy Using Nitric Oxide Synthase Inhibitors Against Endotoxin Shock in Dogs

Surgery Today. 2006  |  Pubmed ID: 16937286

Nitric oxide synthase (NOS) inhibitors were confirmed to correct the hypotension associated with septic shock, but the overall prognosis is often pessimistic. The histological findings failed to show any improvement. In fact, some patients even exhibited signs of exacerbation. The purpose of this study was to investigate the therapeutic effects of NOS inhibitors and catecholamines in dogs suffering from endotoxin shock. The histological changes produced by these agents were also evaluated.

Rapid Assay for Plasma Soluble E-selectin Predicts the Development of Acute Respiratory Distress Syndrome in Patients with Systemic Inflammatory Response Syndrome

Translational Research : the Journal of Laboratory and Clinical Medicine. Dec, 2006  |  Pubmed ID: 17162250

A newly developed rapid immunoassay method for plasma soluble E-selectin (sES) was examined to determine whether it can predict the development of acute respiratory distress syndrome (ARDS) in critically ill patients with systemic inflammatory response syndrome (SIRS). Plasma levels of sES were measured on admission (day 1) to the emergency unit. Development of various types of organ failures including ARDS was compared in the first 5 days of admission (from day 1 to day 5) between patients with normal plasma levels of sES and those with elevated plasma levels of sES. Plasma levels of sES were determined using a newly developed latex agglutination method that takes 20 min to obtain the test results. The normal range of the plasma sES level was 4.8-29.7 ng/mL with this method. Among the patients examined, 22 patients showed elevated sES levels (D(A)E group) and 28 showed normal sES levels (D(A)N group). Development of ARDS was significantly higher in the D(A)E group (15/22, 68.2%) than in the D(A)N group (4/28, 14.3%) (P < 0.001) and that of cardiovascular system failure, renal failure, and coagulation system failure was also significantly higher in the D(A)E group than in the D(A)N group. The mortality rate at 28 days after admission was higher in the D(A)E group (27.3%) than in the D(A)N group (0%) (P < 0.05). Determination of sES levels by this new rapid assay method might be useful for prediction of the development of ARDS in critically ill patients with SIRS, a pathologic condition that has the potential risk for development of multiple organ failure.

The Combined Effects of Multiple Chemotherapeutic Agents for Malignant Glioma Cells

Journal of Neuro-oncology. Aug, 2007  |  Pubmed ID: 17361333

The prognosis of malignant gliomas remains poor, despite the progress of surgery and radiotherapy. Chemotherapy has been shown to prolong an overall survival, but the benefits are still small. To overcome this situation, the optimal regimen of antineoplastic agents is required. In the present study, we investigated the effect of the association of five chemotherapeutic drugs, including ACNU, CBDCA, CDDP, VCR, and VP-16, on cell survival of U87, YKG1, A172, and U251 human glioma cell lines, using median-effect analysis. A synergistic effect was obtained by treatment involving the association of VP-16 with ACNU or CDDP among the combinations of two drugs, and the association of ACNU, CBDCA, and VP-16 in the combination of three drugs. This preclinical screening using median-effect analysis supports the design of clinical trials by indicating more effective combinations of antineoplastic agents for malignant gliomas.

Microscopic Surface Structure of C/SiC Composite Mirrors for Space Cryogenic Telescopes

Applied Optics. Apr, 2007  |  Pubmed ID: 17384720

We report on the microscopic surface structure of carbon-fiber-reinforced silicon carbide (C/SiC) composite mirrors that have been improved for the Space Infrared Telescope for Cosmology and Astrophysics (SPICA) and other cooled telescopes. The C/SiC composite consists of carbon fiber, silicon carbide, and residual silicon. Specific microscopic structures are found on the surface of the bare C/SiC mirrors after polishing. These structures are considered to be caused by the different hardness of those materials. The roughness obtained for the bare mirrors is 20 nm rms for flat surfaces and 100 nm rms for curved surfaces. It was confirmed that a SiSiC slurry coating is effective in reducing the roughness to 2 nm rms. The scattering properties of the mirrors were measured at room temperature and also at 95 K. No significant change was found in the scattering properties through cooling, which suggests that the microscopic surface structure is stable with changes in temperature down to cryogenic values. The C/SiC mirror with the SiSiC slurry coating is a promising candidate for the SPICA telescope.

[Role of Endothelial Dysfunction in the Development of Severe Sepsis--the Pathomechanism, Evaluation by Laboratory Tests and New Therapeutic Strategies]

Rinsho Byori. The Japanese Journal of Clinical Pathology. Mar, 2007  |  Pubmed ID: 17441473

Tumor necrosis factor (TNF) is critically involved in biological responses against various insults. TNF excessively produced by monocytes or macrophages activates endothelial cells and neutrophils, thereby inducing endothelial cell injury. Endothelial cells are capable of inhibiting TNF production by producing prostaglandins that inhibit TNF production. Sensory neurons play an important role in promotion of the endothelial production of prostaglandins by releasing calcitonin gene-related peptide. Neutrophils activated by TNF release a huge amount of neutrophil elastase that is capable of decreasing endothelial prostaglandin production. Consequently, TNF production is enhanced, leading to the development of multi-organ failure in sepsis. E-selectin, an endothelial leukocyte adhesion molecule, is released from the endothelial cell membrane by the action of TNF and exists as soluble E-selectin in plasma. The detection of increases in plasma levels of soluble E-selectin in patients with systemic inflammatory response syndrome predicts the imminent onset of acute respiratory syndrome. Early detection of increases in plasma levels of soluble E selectin by a rapid assay system, developed by the authors, enables early effective treatment of patients with sepsis.

CD98 Immunoreactivity in Multinucleated Giant Cells of Glioblastomas: an Immunohistochemical Double Labeling Study

Neuropathology : Official Journal of the Japanese Society of Neuropathology. Apr, 2008  |  Pubmed ID: 18021193

CD98, which is identical to fusion regulatory protein-1 (FRP-1), has been reported to induce and regulate cell fusion and multinucleated giant cell formation. To investigate the association between CD98 and multinucleated giant cells (MNGCs) in glioblastomas, we investigate the CD98 immunoreactivity of MNGCs and the proliferative potential in CD98 immunoreactive MNGCs in paraffin-embedded sections obtained from patients with glioblastomas. Double immunohistochemical staining for CD98 and Ki67 as a mitotic marker were performed in formalin-fixed and paraffin-embedded specimens obtained from 16 patients with primary glioblastomas including MNGCs. Most CD98 immunoreactive (CD98+) tumor cells were negative for Ki67. CD98+ MNGCs were identified in 15 cases. CD98+ Ki67- MNGCs were identified in 14 cases and ranged in number from one to 48 (6.7 +/- 11.5). CD98- Ki67+ MNGCs were identified in 15 cases and ranged in number from one to 32 (11.1 +/- 9.6). Mitotic index (MI) of CD98+ MNGCs (4.8 +/- 2.7%) was significantly lower than that of CD98- MNGCs (91.1 +/- 24.6%) (P < 0001). These results suggest that multinucleated giant cell formation may be developed by fusion among CD98- producing cells in glioblastomas.

Expression of Vascular Endothelial Growth Factor-A and MRNA Stability Factor HuR in Human Meningiomas

Journal of Neuro-oncology. Jun, 2008  |  Pubmed ID: 18317686

We studied the expression of vascular endothelial growth factor-A (VEGF-A) and mRNA stability factor HuR in 40 supratentorial meningiomas using RT-PCR, ELISA and immunohistochemistry, and analyzed their associations with the clinicopathological characteristics, including microvascular density (MVD), peritumoral brain edema (PTBE), histological subtypes and grades, and the performance of preoperative arterial embolization. Furthermore, we investigated the involvement of HuR in the upregulation of VEGF-A expression using primary meningioma cell cultures. The level of VEGF-A is elevated in meningiomas with PTBE and in higher grade meningiomas. Preoperative arterial embolization did not significantly increase the level of VEGF-A, but it did increase the expression of HuR in tumor tissues. HuR expression was correlated positively with VEGF-A expression in meningioma tissues. In in vitro experiments, hypoxia induced the upregulation of VEGF-A expression and the cytoplasmic translocation of HuR protein in meningioma cells, and inhibition of the cytoplasmic translocation of HuR reduced the upregulation of VEGF-A expression in meningioma cells. These findings suggest that the expression of VEGF-A relates to the development of PTBE with meningiomas and the histological grade, and that HuR is involved in the upregulation of VEGF-A expression in human meningiomas.

Cryogenic Optical Measurements of 12-segment-bonded Carbon-fiber-reinforced Silicon Carbide Composite Mirror with Support Mechanism

Applied Optics. Mar, 2008  |  Pubmed ID: 18327285

A 720 mm diameter 12-segment-bonded carbon-fiber-reinforced silicon carbide (C/SiC) composite mirror has been fabricated and tested at cryogenic temperatures. Interferometric measurements show significant cryogenic deformation of the C/SiC composite mirror, which is well reproduced by a model analysis with measured properties of the bonded segments. It is concluded that the deformation is due mostly to variation in coefficients of thermal expansion among segments. In parallel, a 4-degree-of-freedom ball-bearing support mechanism has been developed for cryogenic applications. The C/SiC composite mirror was mounted on an aluminum base plate with the support mechanism and tested again. Cryogenic deformation of the mirror attributed to thermal contraction of the aluminum base plate via the support mechanism is highly reduced by the support, confirming that the newly developed support mechanism is promising for its future application to large-aperture cooled space telescopes.

Insect Olfactory Receptors Are Heteromeric Ligand-gated Ion Channels

Nature. Apr, 2008  |  Pubmed ID: 18408712

In insects, each olfactory sensory neuron expresses between one and three ligand-binding members of the olfactory receptor (OR) gene family, along with the highly conserved and broadly expressed Or83b co-receptor. The functional insect OR consists of a heteromeric complex of unknown stoichiometry but comprising at least one variable odorant-binding subunit and one constant Or83b family subunit. Insect ORs lack homology to G-protein-coupled chemosensory receptors in vertebrates and possess a distinct seven-transmembrane topology with the amino terminus located intracellularly. Here we provide evidence that heteromeric insect ORs comprise a new class of ligand-activated non-selective cation channels. Heterologous cells expressing silkmoth, fruitfly or mosquito heteromeric OR complexes showed extracellular Ca2+ influx and cation-non-selective ion conductance on stimulation with odorant. Odour-evoked OR currents are independent of known G-protein-coupled second messenger pathways. The fast response kinetics and OR-subunit-dependent K+ ion selectivity of the insect OR complex support the hypothesis that the complex between OR and Or83b itself confers channel activity. Direct evidence for odorant-gated channels was obtained by outside-out patch-clamp recording of Xenopus oocyte and HEK293T cell membranes expressing insect OR complexes. The ligand-gated ion channel formed by an insect OR complex seems to be the basis for a unique strategy that insects have acquired to respond to the olfactory environment.

Expression of Vascular Endothelial Growth Factor-A and MRNA Stability Factor HuR in Human Astrocytic Tumors

Neuropathology : Official Journal of the Japanese Society of Neuropathology. Dec, 2008  |  Pubmed ID: 18498284

High-grade astrocytic tumors, such as glioblastoma, possess rich vascular components, which are necessary for their growth. VEGF-A is considered to be the major mediator of angiogenesis in malignant neoplasms including high-grade astrocytic tumors. The upregulation of VEGF-A expression in tumor cells is induced by two mechanisms: the transcriptional activation and the post-transcriptional stabilization of VEGF-A mRNA. While the former mechanism mediated by hypoxia inducible factor-1 alpha (HIF-1alpha) has been revealed, the latter mediated by mRNA stability factor HuR remains unclear in astrocytic tumors. In the present study, we investigated the expression of VEGF-A and mRNA stability factor HuR in supratentorial astrocytic tumors of 27 adults using RT-PCR, ELISA, and immunohistochemistry. Furthermore, we studied the involvement of HuR in the upregulation of VEGF-A expression using malignant astrocytoma cell lines. In higher-grade astrocytic tumors, the level of VEGF-A and microvascular density were elevated, cytoplasmic expression of HuR, which potentially means the protection of VEGF-A mRNA from degradation by ribonucleases, appeared, and they were correlated positively. In in vitro experiments, the inhibition of the cytoplasmic translocation of HuR protein by leptomycin B (LMB) reduced the upregulation of VEGF-A expression in malignant astrocytic tumor cells under hypoxic conditions. These findings suggest that the expression of VEGF-A and cytoplasmic translocation of HuR relates to the histological grade, and that HuR is involved in the upregulation of VEGF-A expression, in human astrocytic tumors.

Prognostic Significance of the Immunohistochemical Expression of O6-methylguanine-DNA Methyltransferase, P-glycoprotein, and Multidrug Resistance Protein-1 in Glioblastomas

Neuropathology : Official Journal of the Japanese Society of Neuropathology. Aug, 2009  |  Pubmed ID: 19019175

We studied the expression of O(6)-methylguanine-DNA methyltransferase (O(6)-MGMT), P-glycoprotein (Pgp), and multidrug resistance protein-1 (MRP-1) in 23 glioblastomas using RT-PCR, methylation-specific PCR, and immunohistochemistry, and analyzed their association with overall patient survival. Univariate analysis of collected data demonstrated that the expressions of O(6)-MGMT and MRP-1 detected by immunohistochemistry, in addition to the consistent factors, including preoperative Karnofsky performance scale (KPS), radical surgery, and tumor location and extension, were significant prognostic factors for the overall survival (OS) of patients with glioblastoma, who received nimustine (ACNU)-based chemotherapy in association with surgery and radiotherapy. Among them, following multivariate analysis, preoperative KPS, radical surgery, tumor location, and the expression of O(6)-MGMT remained as significant prognostic factors. These findings suggest that immunohistochemical analysis of O(6)-MGMT in patients with glioblastoma can be a useful method to predict the effects of chemotherapy and identify alternative chemotherapeutic regimens for O(6)-MGMT-positive patients.

Smelling the Difference: Controversial Ideas in Insect Olfaction

The Journal of Experimental Biology. Jul, 2009  |  Pubmed ID: 19525421

In animals, the sense of smell is often used as a powerful way to attract potential mates, to find food and to explore the environment. Different animals evolved different systems to detect volatile odorants, tuned to the specific needs of each species. Vertebrates and nematodes have been used extensively as models to study the mechanisms of olfaction: the molecular players are olfactory receptors (ORs) expressed in olfactory sensory neurons (OSNs) where they bind to volatile chemicals, acting as the first relay of olfactory processing. These receptors belong to the G protein-coupled receptor (GPCR) superfamily; binding to odorants induces the production and amplification of second messengers, which lead to the depolarization of the neuron. The anatomical features of the insect olfactory circuit are similar to those of mammals, and until recently it was thought that this similarity extended to the ORs, which were originally annotated as GPCRs. Surprisingly, recent evidence shows that insect ORs can act like ligand-gated ion channels, either completely or partially bypassing the amplification steps connected to the activation of G proteins. Although the involvement of G proteins in insect olfactory signal transduction is still under question, this new discovery raises fascinating new questions regarding the function of the sense of smell in insects, its evolution and potential benefits compared with its mammalian counterpart.

Controversy and Consensus: Noncanonical Signaling Mechanisms in the Insect Olfactory System

Current Opinion in Neurobiology. Jun, 2009  |  Pubmed ID: 19660933

There is broad consensus that olfactory signaling in vertebrates and the nematode C. elegans uses canonical G-protein-coupled receptor transduction pathways. In contrast, mechanisms of insect olfactory signal transduction remain deeply controversial. Genetic disruption of G proteins and chemosensory ion channels in mice and worms leads to profound impairment in olfaction, while similar mutations in the fly show more subtle phenotypes. The literature contains contradictory claims that insect olfaction uses cAMP, cGMP, or IP3 as second messengers; that insect odorant receptors couple to G(alpha)s or G(alpha)q pathways; and that insect odorant receptors are G-protein-coupled receptors or odor-gated ion channels. Here we consider all the evidence and offer a consensus model for a noncanonical mechanism of olfactory signal transduction in insects.

Neuropeptide Feedback Modifies Odor-evoked Dynamics in Caenorhabditis Elegans Olfactory Neurons

Nature Neuroscience. May, 2010  |  Pubmed ID: 20364145

Many neurons release classical transmitters together with neuropeptide co-transmitters whose functions are incompletely understood. Here we define the relationship between two transmitters in the olfactory system of C. elegans, showing that a neuropeptide-to-neuropeptide feedback loop alters sensory dynamics in primary olfactory neurons. The AWC olfactory neuron is glutamatergic and also expresses the peptide NLP-1. Worms with nlp-1 mutations show increased AWC-dependent behaviors, suggesting that NLP-1 limits the normal response. The receptor for NLP-1 is the G protein-coupled receptor NPR-11, which acts in postsynaptic AIA interneurons. Feedback from AIA interneurons modulates odor-evoked calcium dynamics in AWC olfactory neurons and requires INS-1, a neuropeptide released from AIA. The neuropeptide feedback loop dampens behavioral responses to odors on short and long timescales. Our results point to neuronal dynamics as a site of behavioral regulation and reveal the ability of neuropeptide feedback to remodel sensory networks on multiple timescales.

Cryogenic Optical Testing of an 800 Mm Lightweight C/SiC Composite Mirror Mounted on a C/SiC Optical Bench

Applied Optics. Jul, 2010  |  Pubmed ID: 20648171

We tested the optical performance at cryogenic temperatures of an 800 mm diameter lightweight mirror, consisting of carbon-fiber reinforced silicon carbide and with a mass of 11.2 kg. The ceramic composite of the mirror was HB-Cesic, developed by ECM, Germany, and Mitsubishi Electric Corporation, Japan. The test was carried out while the mirror was mounted, via Invar stress relief supports, on a lightweight optical bench also made of HB-Cesic. During the test, both the mirror and the optical bench were cooled to 18 K in a liquid-helium chamber. The test consisted of measuring the mirror's change of surface figure with an interferometer installed outside the cryo-chamber. The cryogenic deformation of the mirror was 110 nm RMS with no significant residual deformation after cooling, which is very promising for the applicability of the HB-Cesic composite to large lightweight cryogenic space optics.