Biomedical subjects

H Yoshida

Publications and source records attributed to H Yoshida.

At least 163 records · Page 9Linked to original sources

PubMed2001

Overexpression of kalpha1 tubulin mRNA in thyroid anaplastic carcinoma.

The expression levels of (k)alpha1 tubulin in 84 benign and malignant thyroid tissues were measured by means of real-time quantitative reverse transcription-polymerase chain reaction. An increased expression of (k)alpha1 tubulin mRNA was observed in all of five anaplastic carcinomas and some of the papillary carcinomas. Expression levels of (k)alpha1 tubulin relative to thyroglobulin mRNA were slightly increased in papillary carcinomas and greatly increased in anaplastic carcinomas. Chemotherapeutic agents which are targeted to microtubules may be considered as an alternative choice for the treatment of anaplastic carcinomas and some differentiated carcinomas in which increased expression of (k)alpha1 mRNA is observed.

Carcinoma↗

PubMed2001

Structure of the YSPTSPS repeat containing two SPXX motifs in the CTD of RNA polymerase II: NMR studies of cyclic model peptides reveal that the SPTS turn is more stable than SPSY in water.

The carboxyl-terminal domain of RNA polymerase II, which is rich in phosphorylation sites, contains 17--52 tandem repeats with the consensus sequence of the heptapeptide, YSPTSPS. The repeat unit of the heptapeptide has two SPXX motifs showing potential beta-turns, SPTS and SPSY. NMR studies were performed in water at pH 4.0 for two cyclic peptides containing one and two repeat units, cyclo-[C(1)R(2)D(3)Y(4)S(5)P(6)T(7)S(8)P(9)S(10)Y(11)S(12)R(13)D(14)C(15)] (peptide 1) and cyclo-[C(1)R(2)D(3)Y(4)S(5)P(6)T(7)S(8)P(9)S(10)Y(11)S(12)P(13)T(14)S(15)P(16)N(17)Y(18)S(19)R(20)D(21)C(22)] (peptide 2), which are cyclized with a disulfide bridge of two Cys residues at the N- and C-termini. SP in 1 and 2 are predominantly in trans form. The following NMR parameters were detected: (1) lower temperature coefficients of amide proton chemical shifts of T7 and S8 in 1, and Tx (T7 or T14), Sx (S8 or S15), Tz (T14 or T7) and Sz (S15 or S8) in 2, (2) significantly large deviation of H(alpha) chemical shifts from its random coil value (Delta H(alpha)) of Pro preceding the Thr (P6 in 1, and Px and Pz in 2), (3) relatively large (3)J(HNH alpha) coupling constants (>8.7 Hz) of T7 in 1 and Tx and Tz in 2, and (4) NOE (d(NN) (i, i+1)) connectivities between the amide protons of T7-S8 and S10-Y11 in 1, and Tx-Sx, S10-Y11, Tz-Sz, and N17-Y18 in 2, although two Pro-Thr-Ser segments in 2 (each of these are annotated by 'x' and 'z') in the first and second repeat units were not distinguishable. Comparison of the NMR parameters between the cyclic peptides and the corresponding linear peptides indicates that cyclization promotes structural stabilization in water. The present NMR data were consistent with the presence of a beta-turn at both SPTS and SPSY: S(5)P(6)T(7)S(8) and S(8)P(9)S(10)Y(11) in 1, and SPxTxSx, SPzTzSz, SP(9)S(10)Y(11), SP(16)N(17)Y(18) in 2. However, the structure of the SPTS segment is more stable than that of the SPSY segment. Conformations consistent with NMR parameters including NOE distances were obtained through molecular dynamics and energy minimization methods. These calculations yielded two stable conformers for the SPTS segment. One of the two corresponds to a type I beta-turn.

Amino Acid Sequence↗

PubMed2001

Low-dose retinoic acid enhances in vitro invasiveness of human oral squamous-cell-carcinoma cell lines.

Retinoids inhibit the proliferation of several types of tumour cells, and are used for patients with several malignant tumours. In this study, we examined the effect of retinoic acids (RAs) on the invasive potentials of the oral squamous cell carcinoma (SCC) cells, BHY and HNt. BHY cells expressed all of retinoid nuclear receptors (RARalpha, beta, gamma, and RXRalpha) and cytoplasmic retinoic acid binding proteins (CRABP1 and CRABP2). HNt cells lacked the expression of RARbeta, but expressed other nuclear receptors and CRABPs. All-trans retinoic acid (ATRA) and 13-cis retinoic acid (13-cisRA) (10(-6)and 10(-7)M) inhibited the growth of the cells, but low-dose ATRA and 13-cisRA (10(-8)M) marginally affected the growth of the cells. Surprisingly, low-dose RAs enhanced the activity of tissue-type plasminogen activator (tPA), and activated pro-matrix metalloproteinases (proMMP2 and proMMP9). Activation of proMMP2 and proMMP9 was inhibited by aprotinin, a serine-proteinase, tPA inhibitor. Furthermore, low-dose RAs enhanced the in vitro invasiveness of BHY cells. These results indicate that low-dose RAs enhances the in vitro invasiveness of oral SCC cells via an activation of proMMP2 and proMMP9 probably mediated by the induction of tPA.

Antineoplastic Agents↗

PubMed2001

Quantitative measurement of thyroglobulin mRNA in peripheral blood of patients after total thyroidectomy.

Previous studies have reported the clinical usefulness of reverse transcription-polymerase chain reaction (RT-PCR) detection of thyroglobulin (TG) mRNA in the peripheral blood of patients with differentiated thyroid carcinoma. To evaluate this usefulness, we measured TG mRNA in the peripheral blood of patients diagnosed with thyroid carcinoma after total thyroidectomy by real-time quantitative RT-PCR using glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA as an internal control. Surprisingly, we detected TG mRNA in all samples obtained after total thyroidectomy, including those from 4 medullary carcinomas. Further, there was no statistical difference in expression levels of TG mRNA in the patients with or without metastasis, and no significant correlation was found between serum TG concentrations and the expression levels of TG mRNA. These results give rise to a question regarding the clinical applications of not only RT-PCR detection but also quantitative measurement of TG mRNA in peripheral blood.

Adolescent↗

PubMed2001

Expression of alpha-synuclein in a human glioma cell line and its up-regulation by interleukin-1beta.

Although alpha-synuclein is expressed primarily in neurons, it is a major component of oligodendroglial and astrocytic inclusions in several neurodegenerative diseases. Recent study has further demonstrated that alpha-synuclein is expressed in cultured rat oligodendrocytes. We determined whether alpha-synuclein might be expressed in astrocytic cells. alpha-Synuclein mRNA and protein were detected in U251 human astrocytic glioma cells and normal human astrocytes, and the levels were increased in the former, but not in the latter, by stimulation with interleukin-1beta in a time- and concentration-dependent manner. Serum deprivation also led to an increase of alpha-synuclein mRNA and protein in U251 cells. Immunofluorescent staining confirmed the cell-associated alpha-synuclein. These findings suggest that human astrocytes can produce alpha-synuclein in culture and that certain inflammatory cytokines and cell stress increase alpha-synuclein expression.

Astrocytes↗

PubMed2001

cDNA microarray analysis of Helicobacter pylori-mediated alteration of gene expression in gastric cancer cells.

Helicobacter pylori infection stimulates several intracellular signaling pathways and is accompanied by increased gene expression in gastric epithelial cells. High-density cDNA microarray was used to characterize the mRNA expression profile of genes in human gastric cancer cells (MKN45, AGS) cocultured with H. pylori. Coculture with cag pathogenicity island (PAI)-positive H. pylori (wild-type) significantly up-regulated mRNA expression in 8 of 2304 genes tested. In 6 (interleukin-8, I(kappaB)alpha, A20, ERF-1, keratin K7, glutathione peroxidase) of the 8 genes, up-regulation was confirmed by RT-PCR. In coculture with isogenic cagE-negative mutant ((Delta)cagE), which encodes a type IV secretion system with other genes in the cag PAI, no significant up-regulation was found. We further analyzed the role of A20. Transfection of expression vector encoding A20 resulted in an inhibition of H. pylori-mediated NF-kappaB activation, indicating that H. pylori-mediated A20 expression could be a negative regulator of NF-kappaB activation. Taken together, these results indicate the importance of microarray technology as a tool for analyzing the complex interplay between H. pylori and the host.

Adenocarcinoma↗

PubMed2001

New ages for the last Australian megafauna: continent-wide extinction about 46,000 years ago.

All Australian land mammals, reptiles, and birds weighing more than 100 kilograms, and six of the seven genera with a body mass of 45 to 100 kilograms, perished in the late Quaternary. The timing and causes of these extinctions remain uncertain. We report burial ages for megafauna from 28 sites and infer extinction across the continent around 46,400 years ago (95% confidence interval, 51,200 to 39,800 years ago). Our results rule out extreme aridity at the Last Glacial Maximum as the cause of extinction, but not other climatic impacts; a "blitzkrieg" model of human-induced extinction; or an extended period of anthropogenic ecosystem disruption.

Animals↗

PubMed2001

Effects of nociceptinNH2 and [Nphe1]nociceptin(1-13)NH2 on rat brain noradrenaline release in vivo and in vitro.

We have investigated the effects of nociceptin/orphanin FQ (NC) receptor agonist NCNH2 and a competitive NC receptor antagonist, [Nphe1]NC(1-13)NH2 on noradrenaline (NA) release in vivo using microdialysis in freely moving animals and in vitro from cerebrocortical slices. One nmol of NCNH2 injected into rat locus coeruleus inhibited NA release from the prefrontal cortex (E(max) 27.4+/-5.7% 30 min after injection) which was partially (33%) reversed by 100 nmol of [Nphe1]NC(1-13)NH2. In cerebrocortical slices NCNH2 inhibited NA release in a concentration-dependent manner (EC50 12 nM, E(max) 29.4%) that was reversed by [Nphe1]NC(1-13)NH2. In both preparations, [Nphe1]NC(1-13)NH2 per se was inactive. These data demonstrate an inhibition of NA release by NCNH2 in a [Nphe1]NC(1-13)NH2 sensitive manner in both in vivo brain microdialysis and in vitro cerebrocortical slices studies in rats.

Animals↗

PubMed2001

Myocardial heat shock proteins during the development of heart failure.

When cardiomyocytes are exposed to stresses, production of heat shock proteins (HSPs) in the cells is enhanced. Such increase in cellular HSP production is considered to bring about tolerance against stress-induced cell damage. The exact role of the cellular HSPs remains unclear. In the present study, HSPs in the viable left ventricular myocardium were determined during the development of heart failure following coronary artery ligation (CAL). The rats after CAL showed symptoms of chronic heart failure (CHF) at the 8th week, but not at the 1st and 2nd weeks. Myocardial HSP27, which may bind to cytoskeletal protein, at the 1st, 2nd, and 8th weeks after CAL was approximately 180, 160, and 125% of the control, respectively. Myocardial HSP60, one of mitochondrial proteins, at the 8th week increased to 140% of the control, whereas those at the 1st and 2nd weeks did not change. Myocardial HSP72, an inducible form of HSP70 family, at the 1st week after CAL increased to 180% of the control, whereas that at the 2nd or 8th week was similar to control. Myocardial heat shock constitutive protein 73 (HSC73), a constitutively expressed form of HSP70 family, and HSP90, which may bind to steroid hormone receptor and actin fiber, of CAL rats did not alter throughout the experiment. These findings show that diverse changes in the production of myocardial HSPs occur during the development of heart failure. Only the increase in myocardial HSP60 production was associated with the development of CHF.

Animals↗

PubMed2001

Synergistic stimulation, by tumor necrosis factor-alpha and interferon-gamma, of fractalkine expression in human astrocytes.

Fractalkine is a CX3C chemonkine that appears to be a neuron-to-microglia signal molecule in the central nervous system. We studied the expression of fractalkine in normal human astrocytes in culture, by using semi-quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. We found that tumor-necrosis factor alpha (TNF-alpha) and interferon-gamma (IFN-gamma) synergistically enhance the expression of fractalkine. The expression of both fractalkine mRNA and protein was increased in time- and concentration-dependent manners in the cells co-stimulated with TNF-alpha and IFN-gamma. Cycloheximide, an inhibitor of protein synthesis, and dexamethasone had no effect on the synergy of the stimulation of fractalkine expression. We conclude that normal human astrocytes produce fractalkine by co-stimulation with pro-inflammatory cytokines and it may serve as a potential signal for immune and inflammatory responses in the central nervous system.

Astrocytes↗

PubMed2001

An oxidized derivative of cholesterol increases the release of soluble vascular cell adhesion molecule-1 from human umbilical vein endothelial cells in culture.

Treatment of human umbilical vein endothelial cells (HUVECs) with 7-ketocholesterol resulted in an increased release of soluble vascular cell adhesion molecule-1 (VCAM-1) into culture medium. 7-Ketocholesterol did not enhance the expression of mRNA for VCAM-1. 7 beta-Hydroxy- or 25-hydroxycholesterol had no effect on soluble VCAM-1 levels. Western blot analysis revealed that soluble VCAM-1, in the conditioned medium of both 7-ketocholesterol-stimulated and control cells, had a molecular size of 100 kDa. Stimulation of the TNF-alpha-treated HUVECs with 7-ketocholesterol further increased the levels of soluble VCAM-1 in the culture medium. Again, 7-ketocholesterol did not affect the VCAM-1 mRNA level, which was enhanced by TNF-alpha. Pretreatment of the cells with tissue inhibitor of membrane metalloproteinase-2 (TIMP-2) completely inhibited the release of VCAM-1 in response to 7-ketocholesterol but TIMP-1 had no effect. Adherence of mononuclear cells to TNF-stimulated HUVEC monolayers was slightly inhibited by 7-ketocholesterol, but this oxysterol did not affect the basal adherence to non-stimulated HUVECs. Immunofluorescent staining of the cells confirmed diffuse perinuclear distribution of VCAM-1 in HUVECs treated with TNF-alpha, but 7-ketocholesterol did not affect the intensity or distribution of immunofluorescence. We conclude that 7-ketocholesterol releases VCAM-1 from the endothelium probably by a proteolytic process.

Blotting, Western↗

PubMed2001

Identification of the G13 (cAMP-response-element-binding protein-related protein) gene product related to activating transcription factor 6 as a transcriptional activator of the mammalian unfolded protein response.

Eukaryotic cells control the levels of molecular chaperones and folding enzymes in the endoplasmic reticulum (ER) by a transcriptional induction process termed the unfolded protein response (UPR). The mammalian UPR is mediated by the cis-acting ER stress response element consisting of 19 nt (CCAATN(9)CCACG), the CCACG part of which is considered to provide specificity. We recently identified the basic leucine zipper (bZIP) protein ATF6 as a mammalian UPR-specific transcription factor; ATF6 is activated by ER stress-induced proteolysis and binds directly to CCACG. Here we report that eukaryotic cells express another bZIP protein closely related to ATF6 in both structure and function. This protein encoded by the G13 (cAMP response element binding protein-related protein) gene is constitutively synthesized as a type II transmembrane glycoprotein anchored in the ER membrane and processed into a soluble form upon ER stress as occurs with ATF6. The proteolytic processing of ATF6 and the G13 gene product is accompanied by their relocation from the ER to the nucleus; their basic regions seem to function as a nuclear localization signal. Overexpression of the soluble form of the G13 product constitutively activates the UPR, whereas overexpression of a mutant lacking the activation domain exhibits a strong dominant-negative effect. Furthermore, the soluble forms of ATF6 and the G13 gene product are unable to bind to several point mutants of the cis-acting ER stress response element in vitro that hardly respond to ER stress in vivo. We thus concluded that the two related bZIP proteins are crucial transcriptional regulators of the mammalian UPR, and propose calling the ATF6 gene product ATF6alpha and the G13 gene product ATF6beta.

Activating Transcription Factor 6↗

PubMed2001

Essential role of the mitochondrial apoptosis-inducing factor in programmed cell death.

Programmed cell death is a fundamental requirement for embryogenesis, organ metamorphosis and tissue homeostasis. In mammals, release of mitochondrial cytochrome c leads to the cytosolic assembly of the apoptosome-a caspase activation complex involving Apaf1 and caspase-9 that induces hallmarks of apoptosis. There are, however, mitochondrially regulated cell death pathways that are independent of Apaf1/caspase-9. We have previously cloned a molecule associated with programmed cell death called apoptosis-inducing factor (AIF). Like cytochrome c, AIF is localized to mitochondria and released in response to death stimuli. Here we show that genetic inactivation of AIF renders embryonic stem cells resistant to cell death after serum deprivation. Moreover, AIF is essential for programmed cell death during cavitation of embryoid bodies-the very first wave of cell death indispensable for mouse morphogenesis. AIF-dependent cell death displays structural features of apoptosis, and can be genetically uncoupled from Apaf1 and caspase-9 expression. Our data provide genetic evidence for a caspase-independent pathway of programmed cell death that controls early morphogenesis.

Animals↗

PubMed2001

Synthesis and characterization of bis(mu-hydroxo)diiron(III) complex of N-(4-nitro-2-hydroxy)phenylmethyl-N-(2-pyridylethyl)-N-(2-pyridylmethyl)amine and hydroxylation reaction of alkane.

Bis(mu-hydroxo)diiron(III) complex, [Fe2III(mu-OH)2(NE)2](NO3)2 x 3H2O (3) (N-(4-nitro-2-hydroxy)phenylmethyl-N-(2-pyridylethyl)-N-(2-pyridylmethyl)amine = HNE, where H denotes a dissociable proton of the p-nitrophenol group), has been prepared and characterized by X-ray crystallography, electronic and magnetic spectroscopies.

Alkanes↗

PubMed2001

IL-7 prevents both caspase-dependent and -independent pathways that lead to the spontaneous apoptosis of i-IEL.

Intestinal intraepithelial lymphocytes (i-IEL) readily undergo spontaneous apoptosis in vitro through an unclear mechanism. Here we examined the relationship between caspases, which plays a major role in apoptosis, and IL-7 in the spontaneous apoptosis of i-IEL in vitro. We demonstrated that IL-7 and zVAD prevented the spontaneous apoptosis of i-IEL by approximately 50% and 25% respectively with no additive protection seen when both are used. IL-7 preferentially prevented the apoptosis of gammadelta i-IEL, while zVAD equally prevented the apoptosis of gammadelta and alphabeta i-IEL. Lastly, we demonstrated that the spontaneous apoptosis of i-IEL is associated with a marked increase in caspase activity. Caspase activity was completely inhibited by zVAD, but only slightly by IL-7. Overall these results suggest that two pathways lead to the spontaneous apoptosis of i-IEL, one which is caspase dependent and the other which is caspase independent. IL-7 appears to exert its effect on i-IEL undergoing spontaneous by partially inhibiting both apoptotic pathways.

Amino Acid Chloromethyl Ketones↗

PubMed2001

Compartmentalization of Peyer's patch anlagen before lymphocyte entry.

We have shown that Peyer's patch (PP) first develops as a simple and even cell aggregation during embryogenesis. To investigate when and how such a simple cell aggregation forms the complex PP architecture, we analyzed the distribution of cells expressing IL-7R alpha (PP inducer cells), VCAM-1 (mesenchymal cells), CD11c (dendritic cells), and mature lymphocytes by whole-mount immunostaining of 17.5 days post coitus to 2 days postpartum mouse gut. Our results show that compartmentalization of PP anlagen commences at day 18.5 of gestation by clustering and subsequent follicle formation of IL-7R alpha(+), VCAM-1(+), and CD11c(+) cells. This process adds the primitive architecture of PP anlage with several follicles in which IL-7R alpha(+) cells localize in the center, while VCAM-1(+) and CD11c(+) cells localize at the fringe. This follicle formation is accompanied by the establishment of PP-specific vascular network expressing mucosal addressin cellular adhesion molecule-1. Mature B and T lymphocytes entering in the PP anlage are distributed promptly to their own target zones; B cells to the follicle and T cells to nonfollicular zones. Our analysis of scid/scid mouse indicate that the initial processes including formation of PP-specific vascular network occur in the absence of lymphocytes. These observations indicate that the basic architecture of PP is formed by a set of cell lineages assembled during the initial phase of induction of PP anlagen before entry of mature lymphocytes.

Animals↗

PubMed2001

Molecular basis for hematopoietic/mesenchymal interaction during initiation of Peyer's patch organogenesis.

Mice deficient in lymphotoxin beta receptor (LTbetaR) or interleukin 7 receptor alpha (IL-7Ralpha) lack Peyer's patches (PPs). Deficiency in CXC chemokine receptor 5 (CXCR5) also severely affects the development of PPs. A molecular network involving these three signaling pathways has been implicated in PP organogenesis, but it remains unclear how they are connected during this process. We have shown that PP organogenesis is initiated at sites containing IL-7Ralpha(+) lymphoid cells and vascular cell adhesion molecule (VCAM)-1/intercellular adhesion molecule (ICAM)-1 expressing nonlymphoid elements. Here we characterize these lymphoid and nonlymphoid components in terms of chemokine signals. The lymphoid population expresses CXCR5 and has a strong chemotactic response to B lymphocyte chemoattractant (BLC). Importantly, chemokines produced by VCAM-1(+)ICAM-1(+) nonlymphoid cells mediate the recruitment of lymphoid cells. Furthermore, we show that these VCAM-1(+)ICAM-1(+) cells are mesenchymal cells that are activated by lymphoid cells through the LTbetaR to express adhesion molecules and chemokines. Thus, promotion of PP development relies on mutual interaction between mesenchymal and lymphoid cells.

Animals↗

PubMed2001

XAFS study on active Pr sites in zeolite as a photocatalyst for decomposition of nitrous oxide.

The praseodymium-exchanged mordenite degassed at 873 K acted as a highly active heterogeneous photocatalyst for the stoichiometric decomposition of N2O. Analysis of Pr L3-edge EXAFS revealed that the Pr species were isolated each other in the large channel of zeolite, and that the active Pr species were coordinated by ca. four oxygen atoms and one Al atom. On the other hands, the inactive Pr species are surrounded by ca. 10 oxygens of adsorbed waters. The former low-coordinated Pr species allowed a strong adsorption of N2O, which could be the first step of the decomposition reaction.

Journal Article↗