Biomedical subjects

T Kikuchi

Publications and source records attributed to T Kikuchi.

At least 109 records · Page 6Linked to original sources

PubMed2000

Detection of mRNAs in Peyer's patches of the developing mouse embryo.

We describe a method to identify cells expressing mRNA of interest in the developing digestive tract by whole mount in situ hybridization with digoxigenin-labeled RNA probes. In preparing samples, serosal tissue surrounding the intestine was removed. Enzymatic reactions and probe concentrations were optimized. Furthermore, polyvinyl alcohol was included in the reaction mixture for the color development of alkaline phosphatase conjugated to the antibody against digoxigenin. These modifications improved the sensitivity and enabled us to identity cells that express mRNA in embryonic intestine. Using the antisense probe for VCAM-1, the protein product of which is an immunohistochemical marker of the Peyer's patch in the embryonic intestine, cells expressing mRNA were identified as spot-like clusters in Peyer's patches, confirming the validity of the method. With this method, mRNAs of both lymphotoxins alpha and beta, key molecules for peripheral lymphoid organ development, were found to be confined to the Peyer's patch in the developing intestine. Whole mount in situ hybridization analysis is a useful tool for exploring spatio-temporal expression profiles of mRNA in the developing immune organs.

Animals↗

PubMed2000

Regulation of murine airway eosinophilia and Th2 cells by antigen-conjugated CpG oligodeoxynucleotides as a novel antigen-specific immunomodulator.

The characteristic features of bronchial asthma reflect the orchestrated activity of Th2 cells. Oligodeoxynucleotides containing CpG motifs (CpG) have recently been highlighted as an immunomodulator that biases toward a Th1-dominant phenotype. We have previously reported that intratracheal coadministration of CpG and allergen inhibited airway eosinophilia and hyperresponsiveness in a synergistic manner. To substantiate the synergism between CpG and Ag, we introduced a covalently linked conjugate between CpG and Ag and examined the efficacy on airway eosinophilia and Th2 cytokine production. We found that the conjugated form of CpG plus Ag was 100-fold more efficient in regulating airway eosinophilia than the unconjugated mixture. The inhibitory effects lasted for at least 2 mo. The inhibition of airway eosinophilia by the conjugate was Ag specific and associated with an improvement of the airway hyperresponsiveness and the unresponsiveness of the Ag-specific Th2 cells in the regional lymph nodes. The CpG-Ag conjugate was 100-fold more effective than the unconjugated mixture for inducing in vitro Th1 differentiation in an IL-12-dependent manner. Our data show that CpG conjugated to Ag can work as a novel Ag-specific immunomodulator and imply that inhalation of allergen-CpG conjugate could be a desensitization therapy for patients with bronchial asthma.

Adjuvants, Immunologic↗

PubMed2000

Kinetics of a finite one-dimensional spin system as a model for protein folding.

Simple spin models are used to analyze the kinetic nature of lowest energy state formation of the spin systems as models of protein folding kinetics. The models employed in the present paper are based on the spin systems as models of biopolymers previously proposed by the author for the analysis of the equilibrium nature of transitions [T. Kikuchi, Biophys. Chem. 65 (1997) 109]. In particular, the effect of frustrations on the kinetics is investigated with the Monte Carlo simulations in this study. The results show that the kinetics of the present systems are characterized by the ratio of foldables (pathways on the energy landscape that to lead to the lowest energy state) and the temperature dependence of the mean first passage time of foldables. We also discuss the free energy profile of the present models and the relation of the present results to the kinetics of actual proteins.

Algorithms↗

PubMed2000

Catalytic enantioselective protonation of lithium enolates with chiral imides

The catalytic enantioselective protonation of simple enolates was achieved using a catalytic amount of chiral imides and stoichiometric amount of achiral proton sources. Among the achiral proton sources examined in the protonation of the lithium enolate of 2,2,6-trimethylcyclohexanone catalyzed by (S,S)-imide 1, 2, 6-di-tert-butyl-p-cresol (BHT) and its derivatives gave the highest enantiomeric excess. For example, 90% ee of (R)-enriched ketone was obtained when (S,S)-imide 1 (0.1 equiv) and BHT (1 equiv) were used. Use of 0.01 equiv of the chiral catalyst still caused a high level of asymmetric induction. For catalytic protonation of the lithium enolate of 2-methylcyclohexanone, chiral imide 6 possessing a chiral amide portion was superior to (S,S)-imide 1 as a chiral proton source and the enolate was effectively protonated with up to 82% ee.

Journal Article↗

PubMed2000

Tubby-like protein 1 as an autoantigen in cancer-associated retinopathy.

Cancer-associated retinopathy (CAR) is a rare paraneoplastic syndrome that is characterized by retinal degeneration. Two cDNA clones, recoverin and tubby-like protein 1 (TULP1), were isolated from a human retinal cDNA library by using serum from a CAR patient as the probe. Both recoverin and TULP1 are retina-specific protein, and TULP1 is a member of tubby gene family. A determination of the recognized amino acid sequence of TULP1 by the patient serum and immunohistochemical studies on the distribution of TULP1 in the retina were done in this study.

Amino Acid Sequence↗

PubMed2000

3,4-dihydro-2(1H)-quinolinone as a novel antidepressant drug: synthesis and pharmacology of 1-[3-[4-(3-chlorophenyl)-1-piperazinyl]propyl]-3,4- dihydro-5-methoxy-2(1H)-quinolinone and its derivatives.

To develop a novel antidepressant drug with central nervous system-stimulating activity, we prepared a series of 1-[omega-(4-substituted phenyl-1-piperazinyl)alkyl]-3, 4-dihydro-2(1H)-quinolinone derivatives and examined their activities by their effects at 30 and 100 mg/kg po on the sleeping time of mice anesthetized with halothane and on the time required for recovery from coma induced in mice by cerebral concussion. We examined their binding affinities for sigma receptors by evaluating their ability to inhibit [(3)H]-1,3-di(o-tolyl)guanidine ([(3)H]DTG) binding to the rat whole brain membrane in comparison with three putative sigma receptor agonists: 1,3-di(o-tolyl)guanidine (DTG, 66), (+)-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2, 6-methano-3-benzazecin-8-ol (SKF10,047, 67), and (+)-1,2,3,4,5, 6-hexahydro-6,11-dimethyl-3-(3-methyl-2-butenyl)-2, 6-methano-3-benzazecin-8-ol (pentazocine, 68). Among the series of derivatives, 1-[3-[4-(3-chlorophenyl)-1-piperazinyl]propyl]-3, 4-dihydro-5-methoxy-2(1H)-quinolinone hydrochloride (34b) and its mesylate (34c), at a dose of 30 mg/kg po, reduced the sleeping time and the time for recovery from coma and they inhibited [(3)H]DTG binding for sigma receptors. The putative sigma receptor agonists reduced the sleeping time and the time for recovery from coma whereas two sigma receptor antagonists, alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazinebutanol hydrochloride (BMY14802, 69) and cis-9-[3-(3, 5-dimethyl-1-piperazinyl)propyl]carbazole dihydrochloride (rimcazole, 70), were inactive in the two tests. Preadministration of the putative sigma receptor antagonists 69 (3 mg/kg po) and 70 (30 mg/kg po) completely antagonized the actions of 34b and the sigma receptor agonists in the test for recovery from coma. These results suggested that 34b and 34c are sigma receptor agonists. Furthermore, a single administration of 1 and 10 mg/kg po 34b and 34c showed antidepressant-like activity by reducing the immobility time in the forced-swimming test with mice, while a tricyclic antidepressant, 10, 11-dihydro-N,N-dimethyl-5H-dibenz[b,f]azepine-5-propanamine hydrochloride (imipramine, 1) (10 and 30 mg/kg po), did not reduce the time after a single administration. 1 reduced the time after repeated administration of 30 mg/kg po once a day for 4 days. The structure-activity relationship of the series of compounds is also discussed.

Animals↗

PubMed2000

Lens epithelium-derived growth factor: effects on growth and survival of lens epithelial cells, keratinocytes, and fibroblasts.

We isolated a clone encoding a protein from a human lens epithelial cell (LEC) cDNA library with antibody (Ab) from a cataract patient and named it "lens epithelium-derived growth factor" (LEDGF). LEDGF is found to be identical to p75, a coactivator of both transcription (1) and pre-mRNA splicing (2). In serum-free medium LEDGF stimulated growth of LECs, cos7 cells, skin fibroblasts, and keratinocytes, and prolonged cell survival. Without LEDGF, the aforementioned cells did not survive. Also in serum-free medium, Ab to LEDGF neutralizing LEDGF blocked cell growth and caused cell death. Thus, LEDGF, a regulatory factor, may play an important role for growth and survival of a wide range of cell types.

Amino Acid Sequence↗

PubMed2000

Quantitative DNA methylation analysis by fluorescent polymerase chain reaction single-strand conformation polymorphism using an automated DNA sequencer.

A novel DNA methylation assay technique, termed bisulfite single-strand conformation polymorphism (bisulfite-SSCP), is a combination of sodium-bisulfite modification and fluorescence-based polymerase chain reaction (PCR)-SSCP. After bisulfite treatment followed by PCR amplification, methylated and unmethylated alleles can be simultaneously separated in a nondenaturing gel using an automated DNA sequencer. Using bisulfite-SSCP, methylation of hMLH1 was detected in a quantitative manner. This method is not only simple, quick, accurate, and quantitative, but detailed information about methylation is also available with less work. Methylation analysis of large numbers of samples for multiple loci will be facilitated by bisulfite-SSCP.

Adaptor Proteins, Signal Transducing↗

PubMed2000

The relationship between persistent secretion of RANTES and residual infiltration of eosinophils and memory T lymphocytes after Helicobacter pylori eradication.

Helicobacter pylori (HP)-infected gastric mucosa displays a conspicuous infiltration of mononuclear cells as well as neutrophils. RANTES is a potent chemoattractant peptide for memory T lymphocytes and eosinophils. RANTES protein concentration and the numbers of RANTES-, CD45RO-, and major basic protein (MBP)-positive cells were therefore evaluated in the gastric mucosa from 51 patients with HP-positive chronic gastritis before and after HP eradication and from 22 HP-negative healthy volunteers. RANTES protein concentration was significantly elevated in HP-positive cases and remained high after HP eradication. The numbers of RANTES-, CD45RO-, and MBP-positive cells were significantly increased in HP-positive cases and were well correlated with RANTES protein levels. All tended to decrease after HP eradication, but did not reach the level of HP-negative cases, even at 24 months after HP eradication. It was concluded that persistent expression and secretion of RANTES were closely related to residual infiltration of memory T lymphocytes and eosinophils, for a prolonged period after HP eradication. This seems to be an important mechanism of prolonged gastric mucosal immune response against HP infection, even after HP eradication, and of persistent mucosal damage and atrophy.

Adult↗

PubMed2000

Expression of keratan sulfate at the arthroplasty surface after cup arthroplasty.

Fibrous tissue which regenerated on the acetabular arthroplasty surface was obtained from a 52-year-old woman who underwent total hip replacement after cup arthroplasty. The histological features of this newly formed fibrous tissue and expression of keratan sulfate, which is a characteristic matrix component of articular cartilage, were studied. Microscopic observation revealed that the arthroplasty surface consisted mainly of fibrous tissue which did not show metachromasia with toluidine blue staining, but there were many nodular structures communicating with the bone marrow. Immunostaining for keratan sulfate revealed clear positive staining around the cells of the nodular structures communicating with the bone marrow, while only weakly positive staining was observed in the superficial layer of the loose fibrous tissue. The present study revealed marked formation of articular cartilaginous tissue in areas having good communication with the bone marrow, which indicates that maintenance of this communication may be necessary to improve the outcome of cup arthroplasty.

Arthroplasty, Replacement, Hip↗

PubMed2000

Hyaluronan in synovial fluid of patients with loose total hip prosthesis. Comparison with hyaluronan in patients with hip osteoarthritis and idiopathic osteonecrosis of femoral head.

The concentration and molecular weight of hyaluronan (HA) in the synovial fluid of the hip joint were determined in 13 patients (aged 62.8 +/- 9.4 years) who had undergone prior total hip arthroplasty(THA), 23 patients (aged 65.0 +/- 8.2 years) with osteoarthritis of the hip joint (OA), and 13 patients (aged 40.2 +/- 2.7 years) with idiopathic osteonecrosis of the femoral head (ION). A sample of synovial fluid was obtained during revision THA because of loosening of the total hip prosthesis for the THA group, and during the first replacement surgery or osteotomy for the OA and ION groups. The concentration of HA in the synovial fluid was 0.64 +/- 0.42 mg/ml in the THA group, 1.07 +/- 0.28 mg/ml in the OA group, and 1.30 +/- 0.56 mg/ml in the ION group. The concentration of HA in the synovial fluid of the THA patients was significantly lower than that of the OA and ION patients (P = 0.0156 vs OA, P = 0.003 vs ION). The molecular weight of HA was 309 +/- 88.3 x 10(4) Da in the THA group, 377 +/- 201 x 10(4) Da in the OA group, and 240 +/- 148 x 10(4) Da in the ION group; these values do not differ significantly (P = 0.259 vs OA, P = 0.174 vs ION). Among the THA patients, there was no relation between the concentration of HA and the age of the patient, length of time since the first operation, or type of prosthesis fixation; there was also no relation between the molecular weight of HA and each of these factors. These results suggest that a pseudosynovial membrane is regenerated after THA, and that it produces HA of the same molecular weight as that in patients with OA and ION, although in smaller quantities.

Adult↗

PubMed2000

Potassium ion recycling pathway via gap junction systems in the mammalian cochlea and its interruption in hereditary nonsyndromic deafness.

In the mammalian cochlea, there are two independent gap junction systems, the epithelial cell gap junction system and the connective tissue cell gap junction system. Thus far, four different connexin molecules, including connexin 26, 30, 31, and 43, have been reported in the cochlea. The two networks of gap junctions form the route by which K+ ions that pass through the sensory cells during mechanosensory transduction can be recycled back to the endolymphatic space, from which they reenter the sensory cells. Activation of hair cells by acoustic stimuli induces influx of K+ ions from the endolymph to sensory hair cells. These K+ ions are released basolaterally to the extracellular space of the organ of Corti, from which they enter the cochlear supporting cells. Once inside the supporting cells they move via the epithelial cell gap junction system laterally to the lower part of the spiral ligament. The K+ ions are released into the extracellular space of the spiral ligament by root cells and taken up by type II fibrocytes. This uptake incorporates K+ into the connective tissue gap junction system. Within this system, the K+ ions pass through the tight junctional barrier of the stria vascularis and are released within the intrastrial extracellular space. The marginal cells of the stria vascularis then take up K+ and return it to the endolymphatic space, where it can be used again in sensory transduction. It is highly probable that mutations of connexin genes that result in human nonsyndromic deafness cause dysfunction of cochlear gap junctions and thereby interrupt K+ ion recirculation pathways. In addition to connexin mutations, other conditions may disrupt gap junctions within the ear. For example, mice with a functionally significant mutation of Brain-4, which is expressed in the connective tissue cells within the cochlea, show marked depression of the endolymphatic potential and profound sensorineural hearing loss. It seems likely that disruption of connective tissue cells by this mutation disrupts K+ ion entry into the stria vascularis and thereby results in loss of endolymphatic potential. The association of sensorineural hearing loss with these genetic disorders provides strong evidence for the necessity of gap junction systems for the normal functioning of the cochlea.

Animals↗

PubMed2000

A novel compound heterozygous mutation in the RDH5 gene in a patient with fundus albipunctatus.

PURPOSE: To report a novel compound heterozygous mutation in the 11-cis retinol dehydrogenase (RDH5) gene in a patient with fundus albipunctatus. METHOD: We examined the RDH5 gene genotype in members of a Japanese family. Clinical examination showed that the proband had fundus albipunctatus and his aunt had retinitis pigmentosa. The RDH5 gene was analyzed by direct genomic sequencing. RESULTS: The proband had a compound heterozygotic missense mutation of Val177Gly (GTC-->GGC) and Arg280His (CGC-->CAC) in his RDH5 gene. His mother had the Arg280His mutation and his father had the Val177Gly mutation, but his father's aunt who has typical retinitis pigmentosa had the wild type RDH5 gene. The occurrence of Val177Gly has not been reported in the RDH5 gene of fundus albipunctatus. CONCLUSION: A novel compound heterozygous missense mutation in the RDH5 gene was found in a patient with fundus albipunctatus.

Alcohol Oxidoreductases↗

PubMed2000

Gap junction systems in the mammalian cochlea.

Recent findings that a high proportion of non-syndromic hereditary sensorineural hearing loss is due to mutations in the gene for connexin 26 indicate the crucial role that the gene product plays for normal functioning of the cochlea. Excluding sensory cells, most cells in the cochlea are connected via gap junctions and these gap junctions appear to play critical roles in cochlear ion homeostasis. Connexin 26 occurs in gap junctions connecting all cell classes in the cochlea. There are two independent systems of cells, which are defined by interconnecting gap junctions. The first system, the epithelial cell gap junction system, is mainly composed of all organ of Corti supporting cells, and also includes interdental cells in the spiral limbus and root cells within the spiral ligament. The second system, the connective tissue cell gap junction system, consists of strial intermediate cells, strial basal cells, fibrocytes in the spiral ligament, mesenchymal cells lining the bony otic capsule facing the scala vestibuli, mesenchymal dark cells in the supralimbal zone, and fibrocytes in the spiral limbus. One function of these gap junctional systems is the recirculation of K(+) ions from hair cells to the strial marginal cells. Interruption of this recirculation, which may be caused by the mutation in connexin 26 gene, would deprive the stria vascularis of K(+) and result in hearing loss.

Animals↗

PubMed2000

Protective effects of murine recombinant interferon-beta administered by intravenous, intramuscular or subcutaneous route on mouse hepatitis virus infection.

The significance of the route for administration of murine recombinant interferon-beta (IFN-beta) for inducing its therapeutic effects has been studied. BALB/c mice were daily injected intravenously, intramuscularly or subcutaneously with 1.5x10(3), 1. 5x10(4), or 1.5x10(5) IU of IFN-beta, from one day before to 8th day after mouse hepatitis virus (MHV-2) challenge. All mice received IFN-beta survived significantly longer than those without IFN. In the liver of those IFN-treated mice, viral growth and the histopathological damages were extremely alleviated. These results suggest that, irrespective of the differences in the route of administration, IFN-beta markedly suppressed viral activity when its administration was started prior to viral infection. For clinical use, however, further studies are needed on the optimal route for administration if IFN-beta is given after viral infection.

Animals↗

PubMed2000

Cisplatin-induced apoptotic cell death in Mongolian gerbil cochlea.

Cisplatin is well known to cause cochleotoxicity. In order to determine the underlying mechanisms of cisplatin-induced cell death in the cochlea, we investigated the apoptotic changes and the expression of bcl-2 family proteins controlling apoptosis. Mongolian gerbils were administered 4 mg/kg/day cisplatin consecutively for 5 days. The cisplatin-treated animals showed a significant deterioration in the responses of both distortion product otoacoustic emissions and the endocochlear potential as compared with those of the age-matched controls, suggesting outer hair cell and stria vascularis dysfunction. The presence of DNA fragmentation revealed by a terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling method was recognized in the organ of Corti, the spiral ganglion, and the stria vascularis in the cisplatin-treated animals whereas almost negative results were obtained in the control animals. The nuclear morphology obtained by Hoechst 33342 staining revealed pyknotic and condensed nuclei, confirming the presence of the characteristic features of apoptosis. A significant increase and reduction in the number of bax- and bcl-2-positive cells, respectively, following cisplatin treatment was observed in the cells of the organ of Corti, the spiral ganglion, and the lateral wall. These findings suggest a critical role for bcl-2 family proteins in the regulation of apoptotic cell death induced by cisplatin. The underlying mechanisms of the cisplatin-induced cell death are discussed.

Animals↗

PubMed2000

Molecular modeling of human serum transferrin for rationalizing the changes in its physicochemical properties induced by iron binding. Implication of the mechanism of binding to its receptor.

In order to rationalize the physicochemical properties of human serum-transferrin (STf) and the STf-receptor (TfR) recognition process, we have tried to predict the 3D structures of apo- and iron-loaded STf using a homology modeling technique to study the changes in the structural characteristics that take place upon the uptake of iron by STf in solution. The crystal structures of both forms for ovotransferrin were used as templates for the STf modeling. The modeled structure of STf gave a satisfactory interpretation for the typical physicochemical properties such that (1) STf has a negative electrophoretic mobility and its value increases with iron uptake, and (2) the radius of gyration Rg of Tf decreases with iron uptake. It was found that upon iron binding, interdomain closures take place with large movements of the NII and CII subdomains comprising the N- and C-lobes in STf through a hinge-bending motion, accompanied by the opening of the bridge region with a displacement of more than 15 A. Moreover, in view of the findings from our capillary electrophoresis experiments that the electrostatic interactions significantly contribute to a specific binding of Fe2-STf with TfR, it is inferred that the connecting (bridge) and its neighboring region associated with a surface exposure of negative charge play an important role in the STf-receptor recognition process.

Amino Acid Sequence↗

PubMed2000

A CoMFA analysis with conformational propensity: an attempt to analyze the SAR of a set of molecules with different conformational flexibility using a 3D-QSAR method.

CoMFA analysis, a widely used 3D-QSAR method, has limitations to handle a set of SAR data containing diverse conformational flexibility since it does not explicitly include the conformational entropic effects into the analysis. Here, we present an attempt to incorporate the conformational entropy effects of a molecule into a 3D-QSAR analysis. Our attempt is based on the assumption that the conformational entropic loss of a ligand upon making a ligand-receptor complex is small if the ligand in an unbound state has a conformational propensity to adopt an active conformation in a complex state. For a QSAR analysis, this assumption was interpreted as follows: a potent ligand should have a higher conformational propensity to adopt an 'active-conformation'-like structure in an unbound state than an inactive one. The conformational propensity value was defined as the populational ratio, Nactive/Nstable, of the number of energetically stable conformers, Nstable, to the number of 'active-conformation'-like structures, Nactive. The latter number was calculated by counting the number of conformers that satisfied the structural parameters deduced from the active conformation. A set of SAR data of imidazoleglycerol phosphate dehydratase inhibitors containing 20 molecules with different conformational flexibility was used as a training set for developing a 3D structure-activity relationship by a CoMFA analysis with the conformational propensity value. This resulted in a cross-validated squared correlation coefficient of the CoMFA model with the conformational propensity value (Rcross2 = 0.640) higher than that of the standard CoMFA model (Rcross2 = 0.431). Then we evaluated the quality of the CoMFA models by predicting the inhibitory activity for a new molecule.

Models, Molecular↗