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Biomedical subjects

S Takagi

Publications and source records attributed to S Takagi.

At least 235 records · Page 13Linked to original sources
PubMed1996

Identification of plexin family molecules in mice.

By screening of E17.5 mouse brain cDNA libraries, we isolated two cDNAs encoding new plexin-like proteins. Sequencing revealed that these two proteins were type 1 membrane proteins which showed over 60% identity at the amino acid level to mouse plexin 1. Moreover, putative extracellular segments of these two proteins had three repeats of a cysteine-rich domain which is a common motif for plexin proteins. Thus, we named these two proteins mouse plexin 2 and mouse plexin 3. We obtained mouse plexin 3 cDNA clones in which a part of protein-coding region was deleted. Also, Northern blot analysis showed molecular heterogeneity in mouse plexin 2 mRNAs. These findings indicate that in the mouse, plexins comprise a molecular family (the plexin family).

Alternative Splicing↗
PubMed1996

Identification of a neuronal cell surface molecule, plexin, in mice.

We searched for mouse homologues of the cell adhesion protein plexin which was originally found in Xenopus, and obtained a cDNA encoding a plexin-like protein. We referred to this protein as mouse plexin 1. The overall amino acid identity between mouse plexin 1 and Xenopus plexin was 84%. As in the Xenopus plexin, the extracellular segment of mouse plexin 1 protein possessed three cysteine-rich domains which showed significant homology with the cysteine-rich domain of the c-Met proto-oncogene protein product (c-Met protein) and Met-like receptor protein tyrosine kinases. Northern blot analysis indicated that mouse plexin 1 was predominantly expressed in the brain.

Amino Acid Sequence↗
PubMed1996

Involvement of transforming growth factor beta1 in autocrine enhancement of gelatinase B secretion by murine metastatic colon carcinoma cells.

We have reported previously that highly metastatic LuM1 cells derived from colon carcinoma colon 26 secrete larger amounts of gelatinase B than NM11 cells with poor metastatic potential, and that an increase in this gelatinase B secretion can be induced by autocrine factors (Hyup et A, Cancer Res., 54: 3611-3616, 1994). In the present study, a partial characterization was achieved by comparison of the autocrine factor preparation (fraction G) from serum-free medium conditioned with metastatic LuM1 cells with soluble factors known to stimulate gelatinase B secretion. Secretion of gelatinase B by LuM1 cells was augmented by tumor necrosis factor alpha, transforming growth factor beta1 (TGF-beta1), interleukin 1beta, or epidermal growth factor, and specific neutralizing antibodies abolished the induced increases. Platelet-derived growth factor and insulin-like growth factor 1 had no effect on gelatinase B secretion by LuM1 cells. The enhancement of gelatinase B secretion by fraction G was partially inhibited by the antibody to TGF-beta1. TGF-beta1 was detected in both active and latent forms in serum-free medium conditioned with LuM1 or NM11 cells, with the amount of TGF-beta1 higher in the former case. Gelatinase B secretion by LuM1 cells was enhanced by the addition of TGF-beta1 to the culture medium, but that by NM11 cells was not seriously affected, although the latter bound more of the factor. These results indicate the involvement of this growth factor in the autocrine stimulation of gelatinase B secretion by LuM1 cells. However, the autocrine factor effect was not fully explained by TGF-beta1 in the medium, and the involvement of some other unknown factor(s) was thus indicated.

Animals↗
PubMed1996

Sp1 family proteins recognize the U5 repressive element of the long terminal repeat of human T cell leukemia virus type I through binding to the CACCC core motif.

We have identified several nuclear proteins binding to the U5 repressive element (U5RE) at the U5 region of the human T cell leukemia virus type I (HTLV-I) long terminal repeat (LTR). In gel mobility shift assays with the U5RE DNA probe, Jurkat T cell nuclear proteins generated five different complexes, named U5RE binding protein complexes (U5RP)-A1, -A2, -A3, -B, and -C. Only U5RP-C was affected by pretreatment with an excess of poly(dI-dC) and was immunodepressed by anti-Ku/p80 antibodies, suggesting that U5RP-C is a nonspecific complex involving Ku antigen. UV cross-linking showed at least six nuclear proteins involved in the other complexes, including U5RP-A1, -A2, -A3, and -B. The sequence of the binding core element of these specific complexes, determined by competition assays and gel mobility shift assays using a series of the U5RE mutants, is CACCC which is identical to that for the Sp1 transcription factor. LTR with a mutant U5RE, which has no ability to bind with the nuclear proteins, showed stronger promoter activity than LTR with the wild U5RE, suggesting that the specific interaction of these U5RE-binding proteins might result in the U5-mediated repression. U5RP-A1 was supershifted by anti-Sp1 antibodies and U5RP-A2 and -B were supershifted by anti-Sp3 antibodies, suggesting that Sp1 or Sp3 is involved in U5RP-A1 or U5RP-A2 and -B, respectively. Although the other nuclear proteins remain to be characterized, these findings suggest that U5RE-binding proteins in U5RP-A1, -A2, -A3, and -B are involved in HTLV-I gene repression.

Base Sequence↗
PubMed1996

Developmentally regulated expression of a cell surface protein, neuropilin, in the mouse nervous system.

Neuropilin (previously A5) is a cell surface glycoprotein that was originally identified in Xenopus tadpole nervous tissues. In Xenopus, neuropilin is expressed on both the presynaptic and postsynaptic elements in the visual and general somatic sensory systems, suggesting a role in neuronal cell recognition. In this study, we identified a mouse homologue of neuropilin and examined its expression in developing mouse nervous tissues. cDNA cloning and sequencing revealed that the primary structure of the mouse neuropilin was highly similar to that of Xenopus and that the extracellular segment of the molecule possessed several motifs that were expected to be involved in cell-cell interaction. Immunohistochemistry and in situ hybridization analyses in mice indicated that the expression of neuropilin was restricted to particular neuron circuits. Neuropilin protein was localized on axons but not on the somata of neurons. The expression of neuropilin persisted through the time when axons were actively growing to form neuronal connections. These observations suggest that neuropilin is involved in growth, fasciculation, and targeting for a particular groups of axons.

Amino Acid Sequence↗
PubMed1996

Laparoscopic partial hepatectomy and left lateral segmentectomy: technique and results of a clinical series.

BACKGROUND: Technical difficulties have impeded the development of laparoscopic hepatectomy. This article describes a new technique for performing partial hepatectomy and left lateral segmentectomy by means of laparoscopy, and the results in a series of 11 consecutive patients are reported. METHODS: A microwave tissue coagulator is used in combination with an ultrasonic surgical aspirator to divide hepatic parenchyma without pneumoperitoneum. Branched vessels and ducts are clipped and transected. The largest vessels were suture ligated in some cases. The endoscopic linear stapler was used to transect the left hepatic vein for left lateral segmentectomy. The resected liver was maneuvered into a specimen bag and removed. The argon beam coagulator was used to secure hemostasis of the plane of transection. RESULTS: Eleven patients underwent laparoscopic hepatic resection. Indications included isolated metastatic lesion, hepatocellular carcinoma, hemangioma, Wilson's disease, and hemochromatosis. Three patients underwent left lateral segmentectomy, and eight underwent partial hepatectomy. Ten procedures were performed uneventfully; one patient required conversion to open hepatectomy because of excessive bleeding. Notable differences were seen in blood loss compared with open hepatectomy, and no operative complications occurred. Postoperative pain was minimal. CONCLUSIONS: The laparoscopic hepatectomy, especially partial or left lateral segmentectomy, appears to be a viable surgical alternative in selected cases.

Adolescent↗
PubMed1996

Polymeric calcium phosphate cements derived from poly(methyl vinyl ether-maleic acid).

OBJECTIVES: The purpose of this study was to assess the feasibility of forming polymeric calcium phosphate cements from a mixed powder of dicalcium phosphate/tetracalcium phosphate or only tetracalcium phosphate and poly(methyl vinyl ether-maleic acid) (PMVE-Ma), and to study their setting reaction. METHODS: The setting reaction process of the polymeric cements was evaluated by mechanical strength tests, infrared spectroscopy and x-ray diffraction analysis and compared with that of a water-setting calcium phosphate cement. The mechanical strength data were analyzed using ANOVA and Scheffé's multiple comparisons test. RESULTS: Cements prepared from the mixed powder and 25-30 wt% aqueous solutions of PMVE-Ma had high mechanical strength after 24 h storage in distilled water at 37 degrees C. The hardening mechanism depended on an acid-base reaction between the carboxyl groups of PMVE-Ma and the mixed powder, especially its tetracalcium phosphate component. The formation of hydroxyapatite in the polymeric calcium phosphate cement was not detected and is apparently inhibited as a result of the competing reaction of PMVE-Ma with the mixed powder. SIGNIFICANCE: The cement-forming reaction was significantly faster than that of a water-setting calcium phosphate cement and slower than that observed with the mixed powder and polyacids such as poly(acrylic acid). The characteristics of the polymeric cements suggest that the materials may be useful in cavity lining or endodontic sealing.

Analysis of Variance↗
PubMed1996

Effect of mutations on the intracellular localization of Bombyx mori cytoplasmic polyhedrosis virus polyhedrin.

We have already cloned the polyhedrin genes of the wild-type strain H Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) and its mutant, strain A. In this work, polyhedrin genes of mutant BmCPV strains C1 and C2 were cloned and their nucleotide sequences were determined. The polyhedrin amino acid sequences of strains C1 and C2 were compared with that of strain H. Strains C1 and C2 contained two and three sites of mutation in their polyhedrin genes, respectively. Four amino acids (249RLLV) were added at the carboxy terminus of the polyhedrin of strain A, C1 and C2 and the corresponding polyhedrin genes were introduced into a baculovirus expression vector. Intracellular localization of expressed polyhedrin as well as the morphology and localization of polyhedra were investigated by Western blot and microscopy analysis. Recombinant baculovirus containing the polyhedrin gene of strain H produced hexahedral polyhedra in both the cytoplasm and the nucleus. However, the hexahedral polyhedra of strain A were localized only in the nucleus. Normal polyhedra were not observed in cells infected with recombinant baculoviruses expressing strain C1 or C2 polyhedrin genes, but amorphous structures were found in infected cells. Results of expression of a chimaeric luciferase-containing carboxyl-terminal sequence of strain A demonstrated that this sequence was responsible for the nuclear localization. We suggest that a mutation at the carboxy terminus of BmCPV polyhedrin led to nuclear localization of polyhedrin and that several other mutations were responsible for modification of the crystallization pattern of polyhedrin.

Amino Acid Sequence↗
PubMed1996

Alcohol and substance use among Japanese high school students.

In the first large-scale survey on the use of alcohol and tobacco and the inhalation of paint thinner by Japanese high school students, a higher percentage of respondents reported past or regular use of these substances than in a 1978 survey. The survey was conducted in 44 high schools. The 14,438 respondents (ages 15-18 years) represented 9 of Japan's 47 geographically distinct urban and rural prefectures. Most (76%) reported that they had consumed alcohol at some time, and 50% reported drinking on a regular basis. Alcohol consumption, drinking partners, and motivation for drinking were compared by student gender, geographic region, and years of education. Fewer students reported smoking cigarettes: 32% had smoked at some time, and 14% smoked regularly. Inhalation of paint thinner was rare: 3% had purposely inhaled it, and 1% had abused it. A significant percentage of the alcohol drinkers also used tobacco and/or thinner, a tendency that was the same despite differences in gender, grade in high school, and urban or rural geographic region. A tendency toward polysubstance use was evident among these high school students.

Adolescent↗
PubMed1996

Distinctive serial magnetic resonance changes in a young woman with rapidly evolved neurocysticercosis, with positron emission tomography results.

A woman aged 21 years noticed numbness of the left hand, dysarthria, and right hemiparesis. Magnetic resonance imaging (MRI) showed homogeneously enhanced lesions in the bilateral cerebral white matter; these enlarged within 2 weeks, showing ring-like enhancement, and then spontaneously decreased in size and enhancement. Neurocysticercosis was confirmed by repeated, significantly positive serology results and the dramatic response to praziquantel. Subsequently, positron emission tomography (PET) revealed persisting regions of possibly decreased cerebral uptake of [18F]2-fluoro-2-deoxyglucose. This is the first documentation of such distinctive serial MRI changes and the results of PET in neurocysticercosis.

Adult↗
PubMed1996

In vivo induction of apoptosis and immune responses in mice by administration of lipopolysaccharide from Porphyromonas gingivalis.

In vivo administration of Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) to mice induced apoptosis before a specific immune response. Apoptosis was associated with the expression of immunoglobulin and Ia on B cells and of CD5 and several markers on T cells. Apoptosis peaked in the spleen and lymph nodes on day 2, and the second peak occurred in the thymus on day 9. Tumor necrosis factor alpha (TNF-alpha) could mediate apoptosis, because the serum TNF-alpha levels were significantly higher than those of controls at 1 day before apoptosis and recombinant murine TNF-alpha induced apoptosis. The apoptosis induced by Pg-LPS was similar to that induced by Escherichia coli LPS in its basic manner, but it was unique in the response of thymus T cells. It was suggested that Pg-LPS could induce apoptosis for the elimination of early nonspecific activated lymphocytes.

Animals↗
PubMed1996

Differential transactivation of the intercellular adhesion molecule 1 gene promoter by Tax1 and Tax2 of human T-cell leukemia viruses.

Previously, we showed that surface expression of intercellular adhesion molecule 1 (ICAM-1) was strongly upregulated in T cells carrying proviral human T-cell leukemia virus type 1 (HTLV-1) and that the viral transactivator protein Tax1 was capable of inducing the ICAM-1 gene. To determine the responsive elements in the human ICAM-1 gene promoter, a reporter construct in which the 5'-flanking 4.4-kb region of the ICAM-1 gene was linked to the promoterless chloramphenicol acetyltransferase (CAT) gene was cotransfected with expression vectors for Tax1 and Tax2, both of which were separately confirmed to be potent transactivators of the HTLV-1 long terminal repeat (LTR). Tax1 strongly activated the ICAM-1 promoter in all the cell lines tested: three T-cell lines (Jurkat, MOLT-4, and CEM), one monocytoid cell line (U937), and HeLa. Unexpectedly, Tax2 activated the ICAM-1 promoter only in HeLa. By deletion and mutation analyses of the 1.3-kb 5'-flanking region, we found that Tax1 transactivated the ICAM-1 promoter mainly via a cyclic AMP-responsive element (CRE)-like site at -630 to -624 in the Jurkat T-cell line and via an NF-kappaB site at -185 to -177 and an SP-1 site at -59 to -54 in HeLa. On the other hand, Tax2 was totally inactive on the ICAM-1 promoter in Jurkat but transactivated the promoter via the NF-kappaB site at -185 to -177 in HeLa. Gel mobility shift assays demonstrated proteins specifically binding to the CRE-like site at -630 to -624 in Tax1-expressing T-cell lines. Stable expression of Tax1 but not Tax2 in Jurkat subclones enhanced the surface expression of ICAM-1. The differential ability of Tax1 and Tax2 in transactivation of the ICAM-1 gene may be related to the differential pathogenicity of HTLV-1 and HTLV-2.

Gene Products, tax↗
PubMed1996

A case of uveitis associated with chronic active Epstein-Barr virus infection.

Ocular complications of chronic active Epstein-Barr virus infection (CAEBV) have rarely been reported. We describe a 7-year-old girl with CAEBV with associated uveitis. The patient was first observed to have recurrent fever and hepatosplenomegaly in August 1991. She presented with left facial nerve palsy in June 1993. Ocular examination showed right iridocyclitis. Both optic disks were swollen, and the retinal vessels were dilated. Antibody titers to EBV were markedly elevated. Treatment with topical steroids. systemic interleukin-2 and splenectomy dramatically relieved all her symptoms. including the ocular ones.

Antibodies, Viral↗
PubMed1996

Quantitative assessment of the efficacy of amorphous calcium phosphate/methacrylate composites in remineralizing caries-like lesions artificially produced in bovine enamel.

Recent studies show that methacrylate-based composites with amorphous calcium phosphate (ACP) as a filler can release supersaturating levels of calcium and phosphate ions in proportions favorable for apatite formation. These findings suggest that such composites could be effectively used as coatings for remineralizing teeth damaged by tooth decay. To examine this hypothesis, we tested composites in vitro for their efficacy to remineralize artificially formed caries-like lesions in extracted bovine incisors. Single 120-microns-thick sagittal tooth sections were placed in holders that exposed only the carious enamel surface. The exposed surfaces were coated with a 1-mm- to 1.5-mm-thick layer of the composite containing, by mass, 40% apatite, silica, or P2O7(-4)-stabilized ACP and 60% photoactivated resin comprised of Bis-GMA, TEGDMA, HEMA, and ZrM. The photocured composite-coated sections were immersed either in a remineralizing solution for 4 weeks at 37 degrees C (static model) or cyclically immersed in demineralizing (0.5 h) and remineralizing solutions (11.5 h) for 2 weeks (dynamic model). Quantitative digital image analysis of matched 102 microns x 220 microns areas from contact microradiographs taken of the sections before and after immersion showed that lesions coated with ACP-filled composites fractionally recovered 71% +/- 33% of their lost mineral compared with 14% +/- 13% for apatite controls in the static model and 38% +/- 16% compared with -6% +/- 24% in the dynamic model. The results suggest that sealants based on ACP-filled methacrylate composites have the potential to remineralize carious enamel lesions.

Animals↗