Biomedical subjects

K Hashimoto

Publications and source records attributed to K Hashimoto.

At least 91 records · Page 5Linked to original sources

PubMed2001

Cortical silent period in the tongue induced by transcranial magnetic stimulation.

Cortical silent period (SP) of the limb muscles is thought to reflect the cortical excitability. However, the lingual SP has not been examined precisely even in normal subjects. We investigated SP in the tongue induced by transcranial magnetic stimulation (TMS) in 18 controls. Surface electrodes were placed on the lingual dorsum using a bipolar technique. A round coil (13.5 cm in outer diameter) connected with Magstim 200 stimulator was placed on the motor cortex of the tongue, and the intensity of the stimulation was increased stepwise to maximum. SP was detected in all subjects especially at the contralateral side to the stimulated side, without contamination of peripheral SP. The duration of SP depended on the stimulus intensity, while the degrees of muscle contraction did not influence SP. SP of the tongue showed similar characteristics to that of limb muscles. This suggests that SP of lingual muscles can be clinically useful for the evaluation of corticobulbar excitability.

Adult↗

PubMed2001

Roles of glutamate receptor delta 2 subunit (GluRdelta 2) and metabotropic glutamate receptor subtype 1 (mGluR1) in climbing fiber synapse elimination during postnatal cerebellar development.

Climbing fiber (CF) synapse formation onto cerebellar Purkinje cells (PCs) is critically dependent on the synaptogenesis from parallel fibers (PFs), the other input to PCs. Previous studies revealed that deletion of the glutamate receptor delta2 subunit (GluRdelta2) gene results in persistent multiple CF innervation of PCs with impaired PF synaptogenesis, whereas mutation of the metabotropic glutamate receptor subtype 1 (mGluR1) gene causes multiple CF innervation with normal PF synaptogenesis. We demonstrate that atypical CF-mediated EPSCs (CF-EPSCs) with slow rise times and small amplitudes coexisted with typical CF-EPSCs with fast rise times and large amplitudes in PCs from GluRdelta2 mutant cerebellar slices. CF-EPSCs in mGluR1 mutant and wild-type PCs had fast rise times. Atypical slow CF responses of GluRdelta2 mutant PCs were associated with voltage-dependent Ca(2+) signals that were confined to PC distal dendrites. In the wild-type and mGluR1 mutant PCs, CF-induced Ca(2+) signals involved both proximal and distal dendrites. Morphologically, CFs of GluRdelta2 mutant mice extended to the superficial regions of the molecular layer, whereas those of wild-type and mGluR1 mutant mice did not innervate the superficial one-fifth of the molecular layer. It is therefore likely that surplus CFs of GluRdelta2 mutant mice form ectopic synapses onto distal dendrites, whereas those of wild-type and mGluR1 mutant mice innervate proximal dendrites. These findings suggest that GluRdelta2 is required for consolidating PF synapses and restricting CF synapses to the proximal dendrites, whereas the mGluR1-signaling pathway does not affect PF synaptogenesis but is involved in eliminating surplus CF synapses at the proximal dendrites.

Aging↗

PubMed2001

Downregulation of E-cadherin and Desmoglein 1 by autocrine hepatocyte growth factor during melanoma development.

During melanoma development, transformed cells evade keratinocyte-mediated control by downregulating cell adhesion molecules. This study investigated the regulation of cell adhesion by hepatocyte growth factor (HGF) in melanoma. Melanocytes and two melanoma lines, WM164 and WM35, expressed normal level E-cadherin and Desmoglein 1, whereas most melanomas (18 out of 20) expressed no E-cadherin and significantly reduced Desmoglein 1. Overexpression of dominant negative E-cadherin and Desmoglein in melanocytes demonstrated that both molecules contribute to adhesion between melanocytes and keratinocytes. In contrast to melanocytes, most melanomas expressed HGF. All melanocytic cells expressed the HGF receptor c-Met, and autocrine HGF caused constitutive activation of c-Met, MAPK and PI3K. When autocrine activation was induced with HGF-expressing adenovirus, E-cadherin and Desmoglein 1 were decreased in melanocytes, WM164 and WM35. MAPK inhibitor PD98059 and PI3K inhibitor wortmannin partially blocked the downregulation, suggesting that both pathways are involved in this process. c-Met was coimmunoprecipitated with E-cadherin, Desmoglein 1 and Plakoglobin, suggesting that they form a complex (es) that acts to regulate intercellular adhesion. Together, the results indicate that autocrine HGF decouples melanomas from keratinocytes by downregulating E-cadherin and Desmoglein 1, therefore frees melanoma cells from the control by keratinocytes and allows dissemination of the tumor mass.

Autocrine Communication↗

PubMed2001

Identification of sonic hedgehog-responsive genes using cDNA microarray.

Sonic hedgehog (Shh) is a secreted signaling protein that plays important roles in a variety of developmental processes and also in pathogenesis of some human cancers and congenital diseases. Molecules that function downstream of Shh, however, still remain elusive. Here we searched for Shh-responsive genes by using an in-house cDNA microarray. Two genes were newly identified to be Shh responsive in neuroepithelial cell line MNS-70: the metal-binding protein Ceruloplasmin (Cp) and the serine protease inhibitor inter-alpha-trypsine inhibitor heavy chain H3 (ITIH3). In MNS-70 cells, expression of ITIH3 was regulated by Gli zinc-finger transcription factors downstream of Shh, whereas Cp appeared to be regulated by Gli-independent pathways. Cp mRNA was detected in the developing mouse brain, where its expression domain was closely adjacent to that of Shh. These results demonstrate that microarray technology provides a useful tool for studying expression of developmentally regulated genes.

Animals↗

PubMed2001

Exposure to diesel exhaust exacerbates allergen-induced airway responses in guinea pigs.

Diesel exhaust (DE) is a major air pollutant in urban areas. To clarify the effects of DE on the exacerbation of asthma, guinea pigs were exposed 12 h daily to 3 mg/m(3) DE or air for 8 wk with or without sensitization to ovalbumin (OVA). In the DE-exposed sensitized animals, both immediate (IAR) and late (LAR) airway responses were enhanced after the inhalation challenge by OVA, compared with the DE-unexposed sensitized animals. Mucus was greatly accumulated in the airways of DE-exposed sensitized animals during IAR. The number of eosinophils and level of sialic acid concentration in bronchial lavage fluids were also significantly higher in the DE-exposed sensitized animals than in the DE-unexposed control animals. During LAR, intercellular spaces of the bronchial epithelium became enlarged in the DE-exposed sensitized animals, showing infiltration by numerous eosinophils. Albumin concentration was significantly higher in the bronchial lavage fluids from the DE-exposed sensitized animals than in those from the DE-unexposed control animals. These results suggest that exposure to DE enhances mucus hypersecretion and eosinophilic inflammation during IAR. DE exposure also increases airway permeability and airway inflammation during LAR. Thus, DE exposure exacerbates allergen-induced airway responses in guinea pigs.

Allergens↗

PubMed2001

Immune interaction between respiratory syncytial virus infection and allergen sensitization critically depends on timing of challenges.

Severe respiratory syncytial virus (RSV) infection has been hypothesized to be a risk factor for the development of allergy and asthma, but epidemiologic studies in humans have been inconclusive. By use of a well-characterized murine model of RSV infection and allergic sensitization with ovalbumin, the effect of a preceding severe RSV infection on the development of the pulmonary allergic inflammatory response and airway hyperresponsiveness (AHR) was tested. The impact of prior allergic sensitization on RSV-induced illness, as measured by weight loss, also was evaluated. RSV infection before allergic sensitization decreased allergen-induced AHR, production of interleukin-13 in lung tissue, and lung eosinophilia. In contrast, allergic sensitization before RSV infection increased AHR and decreased RSV-related weight loss and lung levels of interferon-gamma but did not alter viral clearance. These data provide evidence that RSV-associated AHR occurs in hosts with allergic responses and that allergic inflammation is diminished when preceded by RSV infection.

Allergens↗

PubMed2001

Cancer chemopreventive activity of carotenoids in the fruits of red paprika Capsicum annuum L.

Capsanthin and related carotenoids isolated from the fruits of red paprika Capsicum annuum L. showed potent in vitro anti-tumor-promoting activity with inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Among them, capsanthin diester and capsorbin diester showed strong inhibitory effects. Furthermore, capsanthin , capsanthin 3'-ester and capsanthin 3,3'-diester , major carotenoids in paprika, exhibited potent anti-tumor-promoting activity in an in vivo mouse skin two-stage carcinogenesis assay using 7, 12-dimethylbenz[a]anthracene as an initiator and TPA as a promoter.

Animals↗

PubMed2001

Overexpression of the Wiskott-Aldrich syndrome protein N-terminal domain in transgenic mice inhibits T cell proliferative responses via TCR signaling without affecting cytoskeletal rearrangements.

Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by thrombocytopenia with small platelets, severe eczema, and recurrent infections due to defects in the immune system. The disease arises from mutations in the gene encoding the WAS protein (WASP), which plays a role as an adaptor molecule in signal transduction accompanied by cytoskeletal rearrangement in T cells. To investigate the functional domain of WASP, we developed transgenic mice overexpressing the WASP N-terminal region (exon 1-5) including the Ena/VASP homology 1 (pleckstrin homology/WASP homology 1) domain, in which the majority of mutations in WAS patients have been observed. WASP transgenic mice develop and grow normally under the specific pathogen-free environment, and showed normal lymphocyte development. However, proliferative responses and cytokine production induced by TCR stimulation were strongly inhibited in transgenic mice, whereas Ag receptor capping and actin polymerization were normal. These findings suggest that overexpressed Ena/VASP homology 1 (pleckstrin homology/WASP homology 1) domain of WASP inhibits the signaling from TCR without coupling of cytoskeletal rearrangement. WASP transgenic mice shown here could be valuable tools for further understanding the WASP-mediated processes.

Actins↗

PubMed2001

Assignment of 118 novel cDNAs of cynomolgus monkey brain to human chromosomes.

In order to isolate genes that may not be represented in current human brain cDNA libraries, we have sequenced about 20,000 sequence tags of cDNA clones derived from cerebellum and parietal lobe of cynomolgus monkeys (Macaca fascicularis). We determined the entire cDNA sequence of approximately 700 clones whose 5'-terminal sequences showed no homology to annotated putative genes or expressed sequence tags in current databases of genetic information. From this, 118 clones with sequences encoding novel open reading frames of more than 100 amino acid residues were selected for further analysis. To localize the genes corresponding to these 118 newly identified cDNA clones on human chromosomes, we performed a homology search using the human genome sequence and fluorescent in situ hybridization. In total, 108 of 118 clones were successfully assigned to specific regions of human chromosomes. This result demonstrates that genes expressed in cynomolgus monkey are highly conserved throughout primate evolution, and that virtually all had human homologs. Furthermore, we will be able to discover novel human genes in the human genome using monkey homologs as probes.

Animals↗

PubMed2001

Presynaptic inhibition caused by retrograde signal from metabotropic glutamate to cannabinoid receptors.

We report a type of synaptic modulation that involves retrograde signaling from postsynaptic metabotropic glutamate receptors (mGluRs) to presynaptic cannabinoid receptors. Activation of mGluR subtype 1 (mGluR1) expressed in cerebellar Purkinje cells (PCs) reduced neurotransmitter release from excitatory climbing fibers. This required activation of G proteins but not Ca2+ elevation in postsynaptic PCs. This effect was occluded by a cannabinoid agonist and totally abolished by cannabinoid antagonists. Depolarization-induced Ca2+ transients in PCs also caused cannabinoid receptor-mediated presynaptic inhibition. Thus, endocannabinoid production in PCs can be initiated by two distinct stimuli. Activation of mGluR1 by repetitive stimulation of parallel fibers, the other excitatory input to PCs, caused transient cannabinoid receptor-mediated depression of climbing fiber input. Our data highlight a signaling mechanism whereby activation of postsynaptic mGluR retrogradely influences presynaptic functions via endocannabinoid system.

Animals↗

PubMed2001

Preliminary evaluation of electrochemical PNA array for detection of single base mismatch mutations.

We report here a preliminary evaluation of a microfabricated disposable-type peptide nucleic acid (PNA) array, with a 20-channel electrode, for the detection of cancer gene c-Ki-ras. Synthetic 15-mer PNA probes complimentary to ras sequence modified with cysteine were immobilized on the gold electrodes on the array. The electrochemical PNA array was reacted with 20-mer oligonucleotide target or 128 bp PCR product for 1 h. The anodic current derived from an electrochemically active DNA binder Hoechst 33258 was measured using the PNA array in the 50 microL of reaction chamber. The anodic current from Hoechst 33258 increased with increasing the concentration of PCR product of ras gene in the range from 10(11) to 10(15) copy mL(-1). The single base mismatch mutations of c-Ki-ras/61 were also detected using the electrochemical PNA array.

Base Pair Mismatch↗

PubMed2001

Sarcoplasmic reticulum Ca(2+) atpase (SERCA) 1a structurally substitutes for SERCA2a in the cardiac sarcoplasmic reticulum and increases cardiac Ca(2+) handling capacity.

Ectopic expression of the sarcoplasmic reticulum (SR) Ca(2+) ATPase (SERCA) 1a pump in the mouse heart results in a 2.5-fold increase in total SERCA pump level. SERCA1a hearts show increased rates of contraction/relaxation and enhanced Ca(2+) transients; however, the cellular mechanisms underlying altered Ca(2+) handling in SERCA1a transgenic (TG) hearts are unknown. In this study, using confocal microscopy, we demonstrate that SERCA1a protein traffics to the cardiac SR and structurally substitutes for the endogenous SERCA2a isoform. SR Ca(2+) load measurements revealed that TG myocytes have significantly enhanced SR Ca(2+) load. Confocal line-scan images of field-stimulated SR Ca(2+) release showed an increased rate of Ca(2+) removal in TG myocytes. On the other hand, ryanodine receptor binding activity was decreased by approximately 30%. However, TG myocytes had a greater rate of spontaneous ryanodine receptor opening as measured by spark frequency. Whole-cell L-type Ca(2+) current density was reduced by approximately 50%, whereas the time course of inactivation was unchanged in TG myocytes. These studies provide important evidence that SERCA1a can substitute both structurally and functionally for SERCA2a in the heart and that SERCA1a overexpression can be used to enhance SR Ca(2+) transport and cardiac contractility.

Animals↗

PubMed2001

Discovery of novel mesangial cell proliferation inhibitors using a three-dimensional database searching method.

A three-dimensional pharmacophore model of mesangial cell (MC) proliferation inhibitors was generated from a training set of 4-(diethoxyphosphoryl)methyl-N-(3-phenyl-[1,2,4]thiadiazol-5-yl)benzamide, 2, and its derivatives using the Catalyst/HIPHOP software program. On the basis of the in vitro MC proliferation inhibitory activity, a pharmacophore model was generated as seven features consisting of two hydrophobic regions, two hydrophobic aromatic regions, and three hydrogen bond acceptors. Using this model as a three-dimensional query to search the Maybridge database, structurally novel 41 compounds were identified. The evaluation of MC proliferation inhibitory activity using available samples from the 41 identified compounds exhibited over 50% inhibitory activity at the 100 nM range. Interestingly, the newly identified compounds by the 3D database searching method exhibited the reduced inhibition of normal proximal tubular epithelial cell proliferation compared to a training set of compounds.

Benzamides↗

PubMed2001

In vivo canine model comparison of cardiohemodynamic and electrophysiological effects of a new antipsychotic drug aripiprazole (OPC-14597) to haloperidol.

The cardiovascular effects of aripiprazole were assessed in comparison with those of haloperidol using a halothane-anesthetized canine model with monophasic action potential monitoring. Aripiprazole (n = 6) or haloperidol (n = 6) was infused over 10 min at escalating doses of 0.03, 0.3, and 3.0 mg/kg with intervals of 20 min between doses. Clinically relevant plasma concentrations were obtained after 0.03-0.3 mg/kg of aripiprazole as well as haloperidol. After 0.03-0.3 mg/kg of aripiprazole, positive chronotropic, inotropic, and dromotropic effects, shortening of the ventricular effective refractory period (ERP) and repolarization phase, and decrease of total peripheral resistance were observed in a dose-related manner. However, in the presence of a beta-blocking dose of esmolol (0.1 mg/kg/min), these changes were not induced. After 3.0 mg/kg of aripiprazole administration, cardiac effects induced by the lower doses were attenuated or disappeared, while the negative chronotropic, dromotropic, and hypotensive actions and prolongation of ERP and repolarization phase were induced. After 0.03 mg/kg of haloperidol, no significant change was observed, except for the decrease of the peripheral resistance. After 0.3-3.0 mg/kg of haloperidol, negative chronotropic, inotropic, and hypotensive actions, intraventricular conduction delay, and prolongation of ventricular ERP and repolarization phase were observed in a dose-related manner accompanied by further decrease of the peripheral resistance. The inhibitory effects of aripiprazole on cardiovascular parameters in dogs were less potent than those of haloperidol at clinically relevant exposures, moreover, aripiprazole, unlike haloperidol, neither induced early afterdepolarization nor prolonged the ventricular electrical vulnerable period. Therefore, aripiprazole can be considered safer to use than haloperidol.

Animals↗

PubMed2001

Solution- and solid-phase synthesis of components for tethered bilayer membranes.

The synthesis of the novel compound PhCH(2)SS(C(24)H(44)N(4)O(10))(C(20)H(41)) (5) for the preparation of tethered bilayer membranes is described. The compound is the all-amide analogue of the previously reported ester-containing membrane-forming material PhCH(2)SS(C(24)H(40)O(14))(C(20)H(41)) (1). The advanced intermediate (C(20)H(41)) C(16)H(28)N(3)O(8) (17) was prepared from the same starting materials using both solution-phase (13% yield) and solid-phase (81% yield) techniques. Monolayers on gold derived from 5 have been analyzed by ellipsometry and FTIR. The monolayers exhibit thicknesses similar to monolayers derived from 1 and possess H-bonded amide functionality.

Journal Article↗

PubMed2001

Effect of non-peptide corticotropin-releasing factor receptor type 1 antagonist on adrenocorticotropic hormone release and interleukin-1 receptors followed by stress.

Previous studies demonstrated that ether-laparotomy significantly increased iodine-125-labeled interleukin-1alpha ([125I]IL-1alpha) binding in the mouse anterior pituitary at 2 h after the onset of stress. Corticotropin-releasing factor (CRF) receptor antagonist, D-Phe CRF (12-41), abolished ether-laparotomy-induced increase in [125I]IL-1alpha binding in the pituitary, showing that CRF plays a pivotal role in the regulation of IL-1 receptors under stress conditions. In an attempt to define the effect of CRA 1000 (2-(N-(2-methylthio-4-isopropylphenyl)-N-ethylamino-4-(4-(3-fluorophenyl)-1,2,3,6-tetrahydropyridin-1-yl)-6-methylpyrimidine), a non-peptide CRF receptor type 1 antagonist on the regulation of hypothalamic-pituitary-adrenal (HPA) axis and IL-1 receptors in the mouse, we measured plasma adrenocorticotropic hormone (ACTH) and corticosterone levels, [125I]IL-1alpha binding and the expression of transcripts for type 1 IL-1 receptor (IL-1R1 mRNA) in the pituitary at 2 h after endotoxin lipopolysaccharide (LPS) treatment or ether-laparotomy stress with or without CRA 1000 pretreatment. A single injection of LPS dramatically increased plasma ACTH and corticosterone levels compared with saline injection. In contrast, plasma ACTH levels were significantly attenuated in response to one LPS injection following oral CRA 1000 pretreatment. LPS-induced plasma corticosterone levels tended to be lower after CRA 1000 pretreatment but it did not reach statistical significance. Ether-laparotomy stress significantly increased plasma ACTH and corticosterone levels at 2 h after the onset of stress and CRA 1000 pretreatment did not affect the peak ACTH and corticosterone levels following stress. Ether-laparotomy stress resulted in a robust increase in [125I]IL-1alpha binding and IL-1R1 mRNA levels in the pituitary. CRA 1000 pretreatment significantly decreased ether-laparotomy stress-induced IL-1R1 mRNA levels but did not affect [125I]IL-1alpha binding. Pretreatment with CRA 1000 without stress significantly increased [125I]IL-1alpha binding and IL-1R1 mRNA levels compared with those in vehicle pretreatment. These data demonstrate differential effects of CRA 1000 in HPA axis following endotoxin and ether-laparotomy stress and complex interactions between CRF and IL-1 receptors during stress.

Adjuvants, Immunologic↗

PubMed2001

Gene organization of bovine BCNT that contains a portion corresponding to an endonuclease domain derived from an RTE-1 (Bov-B LINE), non-LTR retrotransposable element: duplication of an intramolecular repeat unit downstream of the truncated RTE-1.

BCNT (a protein named after Bucentaur or craniofacial development protein 1) has a unique structure in Ruminantia. Bovine BCNT contains a region of the endonuclease domain derived from a truncated RTE-1 (previously called Bov-B LINE), a non-LTR retrotransposable repetitive element, and two repeat units (intramolecular repeat, IR) each with 40 amino acids in the C-terminal region. In contrast the human and mouse BCNT proteins contain one repeat unit and lack the RTE-1-derived portion. The 3' UTR of bovine bcnt cDNA also contains an approximately 300-bp portion homologous to the 3'-part of RTE-1. We examined the bovine bcnt genomic DNA sequence to understand how the bovine bcnt gene has been organized. The sequence of 3' UTR homologous portion was found to more closely resemble the Art2 element than the bovine RTE-1. By PCR screening a bovine/hamster hybrid somatic cell panel, the bovine bcnt gene was mapped to chromosome 18, syntenic human chromosome 16q on which human BCNT is located. The bcnt genomic DNA sequence corresponding to the cDNA downstream of a RTE-1 derived portion reveals that each IR unit is flanked by both 5'-side and 3'-side introns and that 3'-UTR consists of one exon. The alignment of the above sequence with a bovine RTE-1 did not show any significant homology downstream of the endonuclease domain. On the other hand, the alignment of the intron sequences with each other revealed that the six sequential homologous segments ranging in size from 40 to 453 bp existed over a 1 kb long sequence between both the 5'- and 3'-side introns flanking each bovine IR unit. In addition, both the 174-bp of 5'-side intron and 80-bp of 3'-side intron neighboring each 120-bp IR exon are significantly homologous among the two bovine IRs, human IR and mouse IR. These results suggest that a truncated bovine RTE-1 was inserted into the intron upstream of an IR unit of an ancestor bcnt gene and that a duplication of a relatively long region that includes IR occurred in the bovine genome.

3' Untranslated Regions↗

PubMed2001

Interstitial photodynamic therapy with rotating and reciprocating optical fibers.

BACKGROUND: Photodynamic therapy (PDT) is an effective treatment modality that allows selective destruction of malignant tumor cells. However, because of the difficulty in exposing deeper areas of tumors, the modality has strictly limited indications. In this study, the authors introduce a new method for delivering laser light to a three-dimensional, wide area with the purpose of improving the therapeutic value of PDT. METHODS: Three patients with squamous cell carcinoma of the tongue were treated with the present course. After administering porfimer sodium, laser-proof tubes were inserted through the tumor, and optical fibers were passed through the tubes. Pulse laser was emitted from the obliquely prepared fiber tip and distributed toward the target area while rotating and reciprocating the optical fiber. RESULTS: Two patients achieved a complete response without any complications or functional disabilities. The third patient, however, had a partial response and required surgery. CONCLUSIONS: The results indicate the capability of distributing laser light to an entire area of solid tumor. However, the ideal dose of laser light for the treatment of tumors remains unknown. Interstitial PDT will be more efficacious and reliable after the dosimetry is established.

Aged↗