Search PubMed⌕ Search

Biomedical subjects

S Takagi

Publications and source records attributed to S Takagi.

At least 325 records · Page 18Linked to original sources
PubMed1994

An efficient expression vector for transgenic medaka construction.

The transparency and external fertilization of the eggs of medaka (Oryzias latipes) make them ideally suitable for investigating molecular interactions that occur during vertebrate development. Genetically engineered medaka is a potential tool for such studies. It requires several types of suitable expression vectors. To obtain abundant and ubiquitous expression of foreign genes in medaka embryos, we have designed an expression vector that contains the proximal promoter and enhancer elements and polyadenylation signal of the medaka beta-actin gene. The utility of this "all-medaka" expression vector was examined using the Escherichia coli lacZ gene as a reporter gene. Most of the injected embryo showed high gene expression, and several embryos showed ubiquitous expression even at six days after injection. Of nine individuals derived from the injected embryos and grown until adult stage, one produced expression-positive F1 fish. The transgene was identified in these F1 using polymerase chain reaction (PCR). These data revealed that the expression vector based on the expression cassette from the medaka beta-actin gene should be useful for making transgenic medaka. The cloned gene in this cassette vector is stably transmittable and efficiently expressible.

Actins↗
PubMed1994

[p53 expression in colorectal adenoma and early carcinoma].

Expression of p53 was studied immunohistologically in 25 adenomas, 46 cancers in adenoma, and 18 cancers without adenoma, which were obtained by endoscopic polypectomy or mucosal resection. Positive ratio of p53 expression was 100% in cancer without adenoma, 78.3% in cancer in adenoma, and 48% in adenoma. We divided the positive case of p53 expression to three staining patterns, poorly stained type, focal type and diffuse type. The diffuse type was most of cancer without adenoma. In each diagnostic group there was no significant colleration between sex, age, and shape of polyp and the staining pattern. But in cancer without adenoma, there was significant colleration between size of polyp and the staining pattern, and number of the diffuse type increased as the polyp size was larger. Consequently, it was suggested that p53 takes a role of cancerization from adenomas at every step.

Adenoma↗
PubMed1994

[Mixed angioma of the brain: report of two cases].

Clinical features of two patients with mixed angiomas are presented. One patient with a cerebral venous angioma with arterial components was successfully treated with radiation therapy; and the other, who had a common draining vein with cerebellar arteriovenous malformation and venous angioma, was treated with surgical removal of the arteriovenous malformation. These two cases suggested that there is a similarity between the pathogenesis of arteriovenous malformation and venous angioma in the brain.

Adult↗
PubMed1993

(R)-1,2,3,4-tetrahydro[1]benzothieno[2,3-c]pyridines: novel optically active compounds with strong 5-HT1A receptor binding ability exhibiting anticonflict activity and lessening of memory impairment.

(R)-1,2,3,4-Tetrahydro[1]benzothieno[2,3-c]pyridine derivatives (60-114) were synthesized. The (R)-isomers have affinity for the 5-HT1A receptor while the (S)-isomers have no such ability. The affinity of the (R)-isomers was discussed on the basis of structure-activity relationships between the affinity and hydrophobicity of the (R)-isomers. Compounds 71 and 107, which are representative derivative compounds, have anticonflict activity and lessening of memory impairment. In particular, compound 107 cannot bind to receptors other than the 5-HT1A receptor, demonstrating that it is a unique compound with a different mechanism of action from that of conventional anxiolytics.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1993

Enhanced expression of LFA-3 on human T-cell lines and leukemic cells carrying human T-cell-leukemia virus type 1.

Previously, we studied the surface expression of LFA-1 (CD11a/CD18) and ICAM-1 (CD54) in a panel of 16 human T-cell lines and found that those carrying HTLV-1 pro-viruses expressed high levels of ICAM-1. Enhanced expression of ICAM-1 was also seen in fresh leukemic cells from ATL patients. In the present study, we systematically examined the surface expression of 19 different cell-adhesion molecules (CAMs) (the immunoglobulin superfamily, the homing receptors, the integrins, etc.) in a panel of 20 human T-cell lines (6 HTLV-1-negative lines and 14HTLV-1-positive lines). The surface expression of LFA-3 (CD58) was constantly enhanced in HTLV-1-positive T-cell lines except for MT-1, an ATL-derived cell line, which was devoid of a number of CAMs including ICAM-1. LFA-3 proteins and mRNA were found at strongly increased levels in HTLV-1-positive T-cell lines.

Antigens, CD↗
PubMed1993

Detection of 5-bromo-2-deoxyuridine (BrdUrd) incorporation with monoclonal anti-BrdUrd antibody after deoxyribonuclease treatment.

We studied the effects of deoxyribonucleases on the detection of 5-bromo-2-deoxyuridine (BrdUrd) by anti-BrdUrd monoclonal antibodies (mAbs). After DNase I treatment, BrdUrd was detected in cells fixed on slides with the anti-BrdUrd mAbs, B44 and BMC9318. The level of detection related to the degree of DNA digestion. DNA digestion of 25-75% resulted in levels of staining comparable to control preparations in which DNA was denatured by heating with formamide. Staining with the mAbs of DNase I-treated cells was abolished with S1 nuclease, a single-stranded DNA-specific nuclease. When exonuclease III was used after DNase I treatment, the staining intensity of cells fixed on slides increased, and BrdUrd could be detected in suspended cells by flow cytometry. Since this enzymatic method leading to the detection of BrdUrd does not involve cell loss, or destruction of either cellular morphology or epitope reactivity, as occurs with traditional DNA denaturation procedures, it is useful for kinetic studies of phenotypically mixed populations. Furthermore, staining with anti-BrdUrd mAb of cells treated with exonuclease III offers a simple approach to quantitation of apoptotic cells, in which an endogenous endonuclease is activated.

Antibodies, Monoclonal↗
PubMed1993

A novel early antigen associated with Epstein-Barr virus productive cycle.

A murine monoclonal antibody (mAb) 92A recognized a 48-kilodalton Epstein-Barr virus (EBV) early antigen (EA). The mAb stained nuclei of EBV-activated P3HR-1, B95-8 and Akata cells in a distinctive, microgranular immunofluorescence pattern. The 92A antigen was sensitive to methanol-fixation. Expression of the 92A antigen in those cells paralleled diffuse (EA-D) and restricted (EA-R) components of EA, and viral DNA (vDNA) replication. Phosphonoacetic acid did not inhibit expression of the 92A antigen. The colocalization of 92A antigen, EA-D, and vDNA was observed in viral replication compartments of B95-8 cells. On the other hand, in P3HR-1 virus-superinfected Raji cells the percentages of 92A antigen-positive cells were at much lower levels than were EA-D and -R positive cells. Immunofluorescence staining with 92A mAb was blocked by pretreatment with EBV-positive human sera, but not with EBV-negative sera. We conclude that 92A mAb recognizes a novel EA which may function in vDNA replication.

Animals↗
PubMed1993

Optical CT imaging of hemoglobin oxygen-saturation using dual-wavelength time gate technique.

Our results may be summarized as follows: 1. In-vivo hemoglobin oxygen-saturation images of rat brain can be obtained using near-infrared light. 2. The transmitted light has multiple scattered components, which degrade spatial resolution, though most of the scattering can be excluded by a suitable time-gating technique. 3. The hemoglobin oxygen-saturation of the cerebellum is higher than that of the cerebrum in untreated anesthetized rats. Although further improvements in the technique should result in better resolution, we have demonstrated the feasibility of using near-infrared light to obtain in-vivo hemoglobin oxygen-saturation images.

Animals↗
PubMed1993

Polymeric calcium phosphate cements: analysis of reaction products and properties.

Chemical and mechanical properties of water-based polymeric calcium phosphate cements (PCPC) were investigated. These cements were derived from mixing several types of water-soluble polymers, e.g., gelatin, poly(vinyl alcohol) (PVA), and poly(alkenoic acids) such as poly(acrylic acid), with a calcium phosphate cement (CPC) mixture consisting of equimolar amounts of tetracalcium phosphate (TTCP) and anhydrous dicalcium phosphate (DCPA) as well as several other TTCP-containing mixtures. Cement formation was observed with all of the PCPCs. With the gelatin and PVA cements, significant amounts of hydroxyapatite (HA) formation were observed within 24 h. Their setting times and mechanical properties were similar to those of the purely inorganic CPC that is derived from the reaction of TTCP and DCPA in water. Although the mechanical properties of a gelatin-CPC cement were only slightly improved, its handling characteristics were superior to that of CPC. Significantly faster setting and stronger cements were obtained using polycarboxylic acid polymers with CPC. However, only small amounts of HA were observed in these types of polymeric cements even after 1 mon storage in distilled water at 37 degrees C. This research demonstrates the feasibility of preparing several new types of dental cements based on the interaction of water-soluble polymers with a self-setting calcium phosphate powder mixture.

Acrylic Resins↗
PubMed1993

Polymeric calcium phosphate cements: setting reaction modifiers.

In this study, the effects of several additives on the setting behavior and mechanical properties of polymeric calcium phosphate cements were investigated. The cements were derived from a polycarboxylic acid (PCA) and a calcium phosphate cement (CPC) powder that consisted of equimolar amounts of tetracalcium phosphate (TTCP) and dicalcium phosphate (DCPA). Retardation of the setting reaction in the PCA-CPC cements was observed by adding tribasic sodium phosphate and fluorides such as stannous fluoride, zirconium(IV) fluoride and titanium(IV) fluoride. It was found that increasing the concentration of these additives decreased the mechanical strength of the cements. However, improvements in both setting and mechanical properties for the PCA-CPC cements were observed by the combined use of 8% (w/w) stannous fluoride and 10% (w/w) tartaric acid. The mechanical properties of the PCA-CPC cement also were improved by adding calcium acetate, calcium methacrylate, zirconium(IV) sulfate and phosphonoacetic acid.

Acetates↗
PubMed1993

Neuroanatomical substrate for the dorsal light response. II. Effects of kainic acid-induced lesions of the valvula cerebelli on the goldfish dorsal light response.

The dorsal light response (DLR) to the continuously rotating light source was investigated in goldfish that had lesioned the valvula cerebelli. The body inclination was observed and analyzed for every 10 degrees of light rotation. The effects of selective lesions of the medial and lateral valvula cerebelli on the DLR were compared. After the lesion of the medial valvula cerebelli, the fish responded to the rotating light in the similar pattern to that seen preoperatively. However, after the unilateral lesion of the lateral valvula cerebelli, the fish did not respond to light from the side contralateral to the lesion, as if the fish had been unilaterally blindfolded. The lesion induced by kainic acid of the rostral and caudal part of the lateral valvula cerebelli differently influenced on the DLR. The DLR was impaired only after the caudal part of the lateral valvula cerebelli was lesioned by kainic acid. These findings suggest that the lateral valvula cerebelli in goldfish mediate the induction of the visually guided aspects of the DLR.

Animals↗
PubMed1993

The membrane protein A5, a putative neuronal recognition molecule, promotes neurite outgrowth.

The A5 is an unique membrane protein that is expressed in the neurons of the visual system and general somatic sensory system of Xenopus laevis. We cultured retinal explants or trigeminal ganglion neurons on the monolayers of A5-expressing line cells obtained by transfection with the cDNA, and found that the A5-expressing transfectants promote neurite outgrowth for these A5-expressing neurons. The neurite outgrowth-promoting effect was inhibited by anti-A5 antibodies. While, the neurite outgrowth-promotion by the A5 transfectants was not observed for the vestibulocochlear ganglion neurons which lack the A5. These results indicate that the membrane protein A5 is a potent substrate for neurite extension of the A5-expressing neurons but not for the A5-negative ones, suggesting its involvement in specific neuronal interaction.

Animals↗
PubMed1993

The characteristics of alcoholics with HCV infection: histopathologic comparison with alcoholics without HCV infection and chronic type C hepatitis.

Out of 71 patients admitted to the National Kurihama Hospital and a related hospital for alcoholics or hepatic dysfunction, we studied the histopathology of alcoholics with HCV infection. Liver biopsies were divided into three groups depending on whether or not the patient was an alcoholic and anti-HCV antibody positive. The three groups were: (1) 30 HCV-antibody negative alcoholics, (2) 17 HCV-Ab positive alcoholics, and (3) 24 HCV-Ab positive non-alcoholics. Alcoholics developed specific hepatic fibrosis with a solid appearance, and the HCV-Ab negative alcoholics had relatively less lymphocytic infiltration. In contrast, patients with type C virus developed fibrosis with a loose appearance with more lymphocytic infiltrates including lymphfollicular accumulation. HCV-Ab positive alcoholics showed mixed features such as more fibrosis and less piecemeal necrosis and lymphocytic infiltration, especially in follicle formation, than HCV-Ab positive non-alcoholics. Changes of hepatocytes, such as hydropic swelling, fatty change and acidophilic body, increased in severity in the alcoholics compared with the non-alcoholics with viral hepatitis. These findings suggest that the combined exposure to both alcohol and HCV enhances hepatocellular damage, but suppresses inflammatory reactions such as lymphocyte infiltration and follicle formation seen in type C hepatitis.

Alcoholism↗
PubMed1993

Chemical structures of two subunits, A-subunit and B-subunit, of galactose-specific isolectins from Erythrina variegata seeds.

We previously isolated galactose-specific isolectins, EVLI, EVLII, and EVLIII, from the Erythrina variegata seeds [J. Chromatogr. 597, 207-211 (1992)]. The amino acid sequences of the two subunits, A- and B-subunits, of which the isolectins are composed, were determined. A comparison of the amino acid sequences of tryptic peptides from the two subunits revealed seven amino acid substitutions. Among them, Asn46, to which the oligosaccharide chain is linked in the A-subunit, is replaced by Asp46 in the B-subunit, causing the B-subunit to lack one glycosylation site. The N-linked oligosaccharides of these subunits were also analyzed. The N-linked oligosaccharides were first liberated by hydrazinolysis. After N-acetylation, the reducing ends of the oligosaccharides were coupled with 2-aminopyridine, and then the pyridylamino (PA-) derivatives were purified by gel filtration and HPLC on an ODS-silica column. One major sugar chain, accounting for more than 98% of the total, was purified from both species. The structure of this major sugar chain was established to be Man alpha 6(Man alpha 3)(Xyl beta 2)Man beta 4GlcNAc beta 4(Fuc alpha 3)GlcNAc. This finding that there is no structural difference of the sugar chains linked to the two subunits of E. variegata lectins, together with the results of amino acid sequence comparisons, indicates that the difference in molecular mass of these two subunits results almost wholly from the difference in the number of oligosaccharides linked to them.

Amino Acid Sequence↗
PubMed1993

Purification and characterization of a CM-glycinin digesting protease from soybean seeds.

A glycinin-digesting protease was purified from 4-h-imbibed soybean seeds to apparent homogeneity by a combination of DEAE-cellulose, gel filtration and Shodex IEC QA-824 chromatography. The purified soybean protease showed a single band on SDS-PAGE and degraded the carboxymethylated glycinin molecule at neutral or alkaline pH. The glycinin-digesting protease has an apparent molecular mass of 98 kilodaltons as estimated by SDS-PAGE under both reduced and non-reduced conditions. A peptidic substrate for the soybean protease was detected and purified from a tryptic digest of glycinin A5A4B3 complex; it corresponded to Ala(375)-Lys(381) of the B3 subunit. It was found that the protease could hydrolyze the peptide bond between Tyr(378) and Asn(389) of that peptide. The soybean protease was significantly inhibited by PMSF, indicating the endopeptidase is a serine protease. Moreover, the glycinin-digesting activity is also susceptible to EDTA and the inactivated enzyme could be restored by the addition of MnCl2, suggesting that Mn2+ is an important factor for the endopeptidase activity. To our knowledge, this is the first report of purification and characterization of a glycinin-digesting protease from soybean seeds.

Alanine↗