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Biomedical subjects

T Kikuchi

Publications and source records attributed to T Kikuchi.

At least 505 records · Page 28Linked to original sources
PubMed1991

[Transaortic repair of aortopulmonary septal defect in neonate (20 days of age, 2175 gram) using profoundly hypothermic circulatory arrest].

In a 20-days old girl, aortopulmonary septal defect (total defect type) was closed by transaortic patch repair with cardiopulmonary bypass (CPB). The postoperative course was uneventful, and she was discharged 43 days later. This is the youngest and lowest-weight case ever reported in Japan. Various procedures for aortopulmonary septal defect have been proposed with or without CPB. However, transaortic repair with the aid of profoundly hypothermic circulatory arrest seems to be the most preferable corrective surgery for total defect type of neonate and low-weight infant.

Aortopulmonary Septal Defect↗
PubMed1991

Production of cytokines by chondrocytes and its role in proteoglycan degradation.

Increased populations of interleukin 1 (IL-1), tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6) and stromelysin (MMP-3) positive chondrocytes were found in osteoarthritic cartilage with immunoperoxidase microscopy using monospecific antibodies. Chondrocytic cytokine and MMP-3 productions were confirmed with tissue cultures of human osteoarthritic and healthy cartilage and monolayer cultures of rabbit articular chondrocytes. IL-6 production was induced by IL-1 alpha and TNF-alpha. The effects of these cytokines on proteoglycan degradation was also studied. While IL-1 alpha and TNF-alpha accelerated proteoglycan release and caseinase production by chondrocytes, IL-6 had no effect by itself and even depressed the effect of IL-1 alpha. Our results suggest that the cytokine network plays a crucial role in the chondrocyte mediated breakdown of cartilage.

Animals↗
PubMed1990

Reduction of nerve growth factor level in the brain of genetically ataxic mice (weaver, reeler).

By a highly sensitive enzyme immunoassay we measured the level of nerve growth factor (NGF) in the cerebellum and cerebrum of the neurologically mutant mice, weaver, reeler and Purkinje cell degeneration (PCD). A significant decrease in NGF level was observed in both cerebellum and cerebrum of weaver and reeler mutants of either sex. However, there was no such difference between normals and mutants in the case of the PCD mice. These results show that weaver and reeler mice have abnormalities of NGF synthesis and/or degradation not only in the cerebellum but also in the cerebrum.

Animals↗
PubMed1990

Structural organization of the human S-antigen gene. cDNA, amino acid, intron, exon, promoter, in vitro transcription, retina, and pineal gland.

S-Antigen (S-Ag) is a major soluble photoreceptor protein involved in the visual transduction cascade. Several S-Ag cDNAs and a gene coding for human S-Ag were isolated from cDNA and gene libraries. The gene sequences of the coding, noncoding, and 5'-flanking regions of the gene were determined. The S-Ag gene was approximately 50 kbp (kilobase pairs) in length and contained 16 exons and 15 introns. The length of most exons was less than 100 base pairs (bp) and the smallest one was only 10 bp. In contrast, the length of most introns was larger than 2 kbp, and the gene comprised 97% intron and 3% exon. The splice sites for donor and acceptor were in good agreement with the GT/AG rule. The S-Ag protein of 403 amino acid residues was translated from a mRNA of 1.9 kbp, and the mRNA was transcribed from a gene of 50 kbp. The 5'-flanking region of the gene, approximately 1.1 kbp long, had no known regulatory elements for transcription such as TATA, GC, and CCAAT boxes. Interestingly, the 5'-flanking region had promoter activity in an in vitro transcription assay using a nuclear extract of rat brain. A major transcription start site was found at 387 bp upstream from the translation start site ATG. Our results indicate that the sequence of S-Ag promoter differs from other known promoters and may, perhaps, be specific for photoreceptor rod cells and pinealocytes.

Amino Acid Sequence↗
PubMed1990

Conformation in solution of porcine brain natriuretic peptide determined by combined use of nuclear magnetic resonance and distance geometry.

The conformation in solution of porcine brain natriuretic peptide was determined by combined use of NMR spectroscopy and distance geometry. A set of 157 inter-proton-distance constraints was derived from the two-dimensional NOE spectra, and further a set of three hydrogen bond constraints was obtained from analysis of the temperature dependence of labile protons. The five structures with minimal violations were selected after performing distance-geometry calculations starting from 40 random initial conformations. The distance-geometry structures were further refined by the use of restrained energy minimization and restrained molecular dynamics. This structure shows a compact conformation with the carboxy-terminal region, Asn21-Tyr26, folded back to the disulfide-linked loop region, Cys4-Cys20. The characteristics of the conformation determined are as follows: conformations of the three segments interposed by glycine residues, which are Arg7-Ile12, Ser14-Leu18 and Cys20-Arg25, were well defined and the segments Arg7-Ile12 and Cys20-Arg25 are rather close to each other and nearly parallel. The biological significance of these local conformations is discussed on the basis of comparisons with those of atrial natriuretic peptide reported by Kobayashi et al.

Amino Acid Sequence↗
PubMed1990

Metabolism of glycyrrhetic acid by rat liver microsomes-II. 22 alpha- and 24-hydroxylation.

18 beta-Glycyrrhetic acid (GA, an aglycone of glycyrrhizin) is converted to 3-oxo-18 beta-glycyrrhetic acid (3-oxoGA) in the presence of NADP+ by rat liver homogenates, but GA was converted in the presence of NADPH to two other metabolites showing lower Rf values on thin-layer chromatography (TLC) than those of GA and 3-oxoGA by postmitochondrial supernatant of rat liver. The GA-metabolizing activity in the presence of NADPH was localized in microsomes, similar to localization of GA-oxidizing activity to 3-oxoGA. The GA-metabolizing activity required NADPH as a cofactor and O2 for full activity and was inhibited with CO, suggesting the hydroxylation reaction of GA by cytochrome P450. Two metabolites (I and II, lower and higher Rf values on TLC, respectively) were purified on preparative TLC. Mass spectral (MS) analyses of II and methyl ester of acetylated I indicated the formation of monohydroxylated metabolites. On the basis of 3H- and 13C-NMR assignments I and II were identified to be 22 alpha- and 24-hydroxy-18 beta-glycyrrhetic acids, respectively. 3-OxoGA and 3-epi-18 beta-glycyrrhetic acid (3-epiGA) seem to be also hydroxylated at C-22 and C-24. A metabolite of 3-oxoGA showing a lower Rf value was also identified as 22 alpha-hydroxy-3-oxo-18 beta-glycyrrhetic acid by MS and 3H- and 13C-NMR spectral analyses. In 22 alpha-hydroxylation the best substrate was 3-oxoGA, followed by GA and 3-epiGA. On the other hand, for 24-hydroxylation the best substrate was GA, then 3-oxoGA, and 3-epiGA in order. However, 18 alpha-glycyrrhetic acid (18 alpha-GA) was a poor substrate for both 22 alpha- and 24-hydroxylation.

Animals↗
PubMed1990

Interleukin-6 enhances murine megakaryocytopoiesis in serum-free culture.

We investigated the effect of interleukin-6 (IL-6) on murine megakaryocytopoiesis in a serum-free culture system. The addition of IL-6 to a culture containing interleukin-3 (IL-3) resulted in a significant increase in the number of megakaryocyte colonies by bone marrow cells of normal mice. The megakaryocytic progenitors that survive exposure to 5-fluorouracil (5-FU) exhibited a more significant response to IL-6 and IL-3. Polyclonal anti-IL-6 antibody neutralized the stimulatory effect of IL-6 on megakaryocyte colony growth supported by IL-3. Delayed addition experiments and replating experiments of blast cell colonies showed that megakaryocytic progenitors are supported by IL-3 in the early stage of the development but require IL-6 for their subsequent proliferation and differentiation. In addition, IL-6 increased the size of megakaryocytes in granulocyte-macrophage-megakaryocyte colonies. The combination of granulocyte colony-stimulating factor or granulocyte-macrophage colony stimulating factor with IL-3 resulted in an increase in the granulocyte-macrophage colony growth of bone marrow cells of 5-FU-treated mice or normal mice, respectively, but had little effect on the enhancement of pure and mixed megakaryocyte colony growth. These results suggest that IL-6 plays an important role in murine megakaryocytopoiesis.

Animals↗
PubMed1990

Determination of N-nitrosodimethylamine in fish products using gas chromatography with nitrogen-phosphorus detection.

A simple and rapid gas chromatographic method for the determination of N-nitrosodimethylamine (NDMA) in fish products is described. NDMA is extracted from a dried sample with methylene chloride, mixed with n-hexane and passed through a silica gel column. NDMA adsorbed on silica gel is eluted with methylene chloride-diethyl ether (7:3) and the eluate is passed through a Sep-Pak alumina A cartridge column, on which NDMA is adsorbed. NDMA is eluted from the cartridge with diethyl ether-methanol (2:1) and the solution is injected into a gas chromatograph with nitrogen-phosphorus detection. This method does not use solvent evaporation and concentration in the clean-up procedure, which eliminates the loss of volatile NDMA and artifactual formation of NDMA in the analytical procedure. The detection limit is 0.5-1 micrograms/kg and recoveries from salted pollack roe spiked at 40 and 4 micrograms/kg were 96.7% [relative standard deviation (R.S.D.) 3.6%] and 85.0% (R.S.D. 6.8%) respectively.

Aluminum Oxide↗
PubMed1990

Effects of interleukin-3 and interleukin-4 on the development of "connective tissue-type" mast cells: interleukin-3 supports their survival and interleukin-4 triggers and supports their proliferation synergistically with interleukin-3.

We examined the effects of interleukin-3 (IL-3) and interleukin-4 (IL-4) on connective tissue-type mast cells (CTMC) purified from murine peritoneal cells. Although both factors failed to induce extensive proliferation of CTMC, they stimulated CTMC proliferation synergistically in a dose-dependent manner. Pretreatment of CTMC with IL-3 and/or IL-4 indicated that the sustained presence of both factors was required for the development of type 1 mast cell colonies. The delayed addition of IL-3 to cultures of purified CTMC with IL-4 induced no colony formation, while the delayed addition of IL-4 to cultures with IL-3, even on day 28 of culture, induced type 1 colony formation. In replating type 1 colonies induced by IL-3 and IL-4 to secondary cultures with IL-3 alone, few secondary colonies developed. However, the delayed addition of IL-4 to the secondary culture induced many type 1 colonies. The purified CTMC cultured with IL-3 retained the morphological and cytochemical characteristics of CTMC, as well as proliferative ability. These observations indicate that IL-3 supports the survival of CTMC in methylcellulose culture and that IL-4 triggers and supports CTMC proliferation synergistically with IL-3. The serum-free culture of purified CTMC and the culture of single CTMC demonstrated that the synergistic effect of IL-3 and IL-4 on colony growth and the surviving effect of IL-3 on CTMC require no influence from accessory cells or other humoral factors.

Animals↗
PubMed1990

Synergistic action of phorbol ester and IL-3 in the induction of "connective tissue-type" mast cell proliferation.

12-O-Tetradecanoylphorbol-13-acetate (TPA), a tumor-promoting phorbol ester, induced the proliferation of connective tissue-type mast cells (CTMC) synergistically with IL-3 in a methylcellulose culture, as well as with IL-4. The culture of single CTMC and the serum-free culture of CTMC fractionated by Percoll density gradient centrifugation showed that this synergistic action of IL-3 and TPA required no effects of accessory cells or other humoral factors. Although the populations of CTMC acted on by TPA and IL-4 seemed to be close to each other, the velocity of colony growth induced by the simultaneous stimulation of the combination of TPA and IL-4 was faster than that induced by either TPA or IL-4 in the presence of IL-3. In addition, the addition of anti-IL-4 antibody did not neutralize the effect of TPA on the proliferation of CTMC. These results suggest that TPA and IL-4 act on the proliferation of CTMC synergistically with IL-3 via a different pathway. Beside TPA, other phorbol derivatives capable of activating protein kinase C (PKC) induced the proliferation of CTMC synergistically with IL-3, but phorbol derivatives which were unable to activate PKC did not. These results indicate that the activation of PKC is involved in the process of TPA action on the proliferation of CTMC. Furthermore, the facts that 1-oleoyl-2-acetylglycerol, which activated membrane PKC transiently, and staurosporine, which has been reported to inhibit PKC, did not induce the proliferation of CTMC in the presence of IL-3 and that the effect of TPA was exhibited by the sustained stimulation suggest that the action of TPA on the proliferation of CTMC requires at least two steps. The first one is the primary activation of membrane PKC and the second one is the disappearance of PKC from the cells, "down-regulation."

Alkaloids↗
PubMed1990

Insulin-like growth factor-1 (IGF-1), insulin, and epidermal growth factor (EGF) are survival factors for density-inhibited, quiescent Balb/c-3T3 murine fibroblasts.

The great majority of murine Balb/c-3T3 fibroblasts in density-inhibited, quiescent cultures disintegrate and die rapidly when cells are deprived of serum in the medium. Platelet-derived growth factor (PDGF, 5 ng/ml) used alone and insulin-like growth factor (IGF-1, 40 ng/ml) + epidermal growth factor (EGF, 10 ng/ml) prevent most of this cell death and all three factors used together protect close to all cells in the confluent monolayer as determined by counting trypsinized cell suspensions in a Coulter counter. IGF-1 used alone affords a high level of protection during the first 5 hours of incubation in serum-free medium but the protective effect declines subsequently unless EGF is also present. EGF alone has little protective activity. The survival-promoting activity of PDGF used alone or of PDGF + EGF + IGF-1 is not significantly decreased by selective inhibition of messenger precursor RNA transcription with 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole (DRB, 20 or 40 microM), which prevents G1 traverse of the cells mediated by the combination of the three growth factors. DRB also does not interfere with the early protective effect of IGF-1 + EGF, but decreases the late protective effect of this growth factor combination. DRB by itself decreases cell viability in the absence of growth factors or serum. In these experiments viability was assayed by neutral red uptake by using an automated microplate reader. Inhibition of protein synthesis with cycloheximide (CHX, 1 or 5 micrograms/ml) over a 20-hour period was associated with decreased survival of cells protected by IGF-1 + EGF or PDGF + EGF + IGF, but also with decreased survival of cells incubated in the absence of growth factors or serum. The decrease in survival was somewhat more marked when IGF + EGF was present than when PDGF + EGF + IGF-1 was present. Insulin (1,500 ng/ml) mimics the action of IGF-1 (40 ng/ml). The cell survival-enhancing activities of growth factors are concentration dependent. The evidence presented indicates that PDGF, EGF, and IGF-1 (or insulin) act through distinctive mechanisms in affording protection of cells against death. The short-term protective effects of the growth factors are independent of gene expression and may be mediated via metabolic events. Long-term protection may be dependent on gene expression, especially in the case of IGF-1 + EGF.

Animals↗
PubMed1990

Expression of the spike protein of murine coronavirus JHM using a baculovirus vector.

The spike (S) protein of murine coronavirus JHM strain (JHMV) has been expressed in insect cells using a recombinant baculovirus vector. The expressed S protein was shown to be glycosylated and expressed on the cell surface, and to be similar in size and antigenic properties to the S protein produced in mouse cells infected by JHMV. However, no proteolytic cleavage was detected in insect cells. The sera from rats immunised with S protein derived from insect cells reacted in immunoprecipitation and immunofluorescence with the S protein produced in JHMV-infected mouse cells. However, the antisera failed to neutralize the infectivity of JHMV. The studies on two proteins expressed by recombinant baculoviruses, corresponding to the cleavage products S1 and S2, and a panel of monoclonal antibodies suggest that the majority of epitopes which elicit the neutralizing antibodies are present in the N terminal half of the S protein.

Animals↗
PubMed1990

Axonal degeneration of ascending sensory neurons in gracile axonal dystrophy mutant mouse.

The distribution of axonal spheroids was examined in the central nervous system of gracile axonal dystrophy (GAD) mutant mice. Only few spheroids are observed in the gracile nucleus of the medulla in normal mice throughout the period examined, while they are first noted in GAD mice as early as 40 days after birth. The incidence of spheroids shifts from the gracile nucleus to the gracile fasciculus of the spinal cord with the progress of disease, suggesting that the degenerating axonal terminals of the dorsal ganglion cells back from the distal presynaptic parts in the gracile nucleus, along the tract of the gracile fasciculus, toward the cell bodies in the dorsal root ganglion. This phenomenon indicates that the distribution of spheroids is age dependent and reflects a dying-back process in degenerating axons. In addition to the gracile nucleus and the gracile fasciculus, which is one of the main ascending tracts of primary sensory neurons, it was noted that the other primary sensory neurons joined with some of the second-order neurons at the dorsal horn and neurons at all levels of the dorsal nucleus (Clarke's column) are also severely affected in this mutant. The incidence of the dystrophic axons are further extended to the spinocerebellar tract and to particular parts of the white matter of the cerebellum, such as the inferior cerebellar peduncle and the lobules of I-III and VIII in the vermis. These results indicate that this mutant mouse is a potential animal model for human degenerative disease of the nervous system, such as neuroaxonal dystrophy and the spinocerebellar ataxia.

Animals↗
PubMed1990

Ontogeny of the Na(+)-H+ exchanger in rat ileal brush-border membrane vesicles.

The developmental maturation of Na(+)-H+ antiporter was determined using a well-validated brush-border membrane vesicles (BBMV's) technique. Na+ uptake represented transport into an osmotically sensitive intravesicular space as evidenced by an osmolality study at equilibrium. An outwardly directed pH gradient (pH inside/pH outside = 5.2/7.5) significantly stimulated Na+ uptake compared with no pH gradient conditions at all age groups; however, the magnitude of stimulation was significantly different between the age groups. Moreover, the imposition of greater pH gradient across the vesicles resulted in marked stimulation of Na+ uptake which increased with advancing age. Na+ uptake represented an electroneutral process. The amiloride sensitivity of the pH-stimulated Na+ uptake was investigated using [amiloride] 10(-2)-10(-5) M. At 10(-3) M amiloride concentration, Na+ uptake under pH gradient conditions was inhibited 80, 45, and 20% in BBMV's of adolescent, weanling and suckling rats, respectively. Kinetic studies revealed a Km for amiloride-sensitive Na+ uptake of 21.8 +/- 6.4, 24.9 +/- 10.9 and 11.8 +/- 4.17 mM and Vmax of 8.76 +/- 1.21, 5.38 +/- 1.16 and 1.99 +/- 0.28 nmol/mg protein/5 sec in adolescent, weanling and suckling rats, respectively. The rate of pH dissipation, as determined by the fluorescence quenching of acridine orange, was similar across membrane preparation of all age groups studied. These findings suggest for the first time the presence of an ileal brush-border membrane Na(+)-H+ antiporter system in all ages studied. This system exhibits changes in regard to amiloride sensitivity and kinetic parameters.

Amiloride↗
PubMed1990

Use of bovine lung heparin to obviate anaphylactic shock caused by porcine gut heparin.

Intracardiac repair in a 7-year-old girl with tetralogy of Fallot was hampered because of an anaphylactic reaction with cardiopulmonary collapse caused by porcine gut heparin. This patient had an extremely rare case of hypersensitivity to porcine gut heparin but not to bovine lung heparin. Uneventful radical operation could be performed with the use of bovine lung heparin for systemic heparinization during cardiopulmonary bypass.

Anaphylaxis↗
PubMed1990

Cloning of a Bacteroides gingivalis outer membrane protein gene in Escherichia coli.

Gene banks of chromosomal DNA from Bacteroides gingivalis 381 were constructed using the bacteriophage replacement vector lambda L47.1. A clone encoding an outer membrane protein from B. gingivalis was identified by Western blot screening with antiserum raised against the outer membrane fraction of B. gingivalis 381 cells. The DNA insert contained within this phage was cloned into the plasmid vector pACYC184 to create the recombinant plasmid pMD123. An Escherichia coli transformant, MD123, containing pMD123 produced a protein having an apparent molecular weight of 40 kDa. The recombinant protein was purified, and amino acid analysis revealed the recombinant protein to have a relatively high content of hydrophobic amino acids (43.6%). Antiserum against the purified recombinant 40 kDa protein reacted with a polypeptide of similar size in the outer membrane fraction and vesicles of B. gingivalis.

Amino Acids↗
PubMed1990

Liver damage by the crown-of-thorns starfish (Acanthaster planci) lethal factor.

Upon autopsy of mice injected with the crown-of-thorns starfish (Acanthaster planci) lethal factor, a change in color of the liver, swelling of the gall bladder and jaundice were observed. After administration of the lethal factor into mice, activities of glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), lactate dehydrogenase (LDH), acid phosphatase (ACP) and alkaline phosphatase (ALP) were significantly elevated in serum. Hepatic ALP also increased markedly but hepatic GOT, GPT and ACP showed a tendency to decrease. Activity of hepatic LDH first decreased and then returned to control level. Histopathological studies showed that severe degenerative changes such as enlargement and necrosis of hepatocytes were caused in the mouse liver by the lethal factor. These results strongly suggested that the A. planci lethal factor is a potent hepatotoxin.

Animals↗