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Biomedical subjects

A Ueno

Publications and source records attributed to A Ueno.

At least 19 recordsLinked to original sources
PubMed1992

Netropsin specifically enhances RNA polymerase II termination at terminator sites in vitro.

We describe an in vitro system that emulates the specific and efficient transcriptional termination associated with the human gastrin gene terminator in vivo. The system involves a dC-tailed DNA template containing the gastrin gene terminator sequence, purified RNA polymerase II, and purified elongation factor TFIIS. In this system, the basal level of termination by RNA polymerase II at the gastrin gene terminator is specifically enhanced by netropsin, an (A + T)-rich minor groove-binding peptide. This enhanced termination is maintained even with TFIIS, which normally suppresses termination at this site. In vitro termination is terminator sequence-specific. Mutant sequences that reduce or abolish termination in vivo show corresponding reductions in activity in the in vitro system. This in vitro emulation of in vivo activities of wild-type and mutant terminators strongly suggests that netropsin and a putative termination factor may share some aspects of their biochemical mechanisms. The general applicability of this system to the study of RNA polymerase II elongation and termination is suggested by the enhancement of termination seen at both the gastrin and human histone H3.3 gene terminators.

Base Sequence↗
PubMed1992

Suppression of myoelectrical activity of gastric smooth muscle by endogenous gastric prostaglandin E2.

The myoelectrical activity of the gastric smooth muscle, recorded by a bipolar electrode placed at the gastric antrum in rats, could be recorded when the stomach was distended with 5 ml of physiological saline. This activity may be induced by a mucosal reflex and was inhibited both by atropine and by pirenzepine. Replacement of physiological saline with solutions of NaCl suppressed this myoelectrical activity. This suppression was dependent on the concentrations of NaCl in the solutions, from 0.3 to 1.0 M. Pretreatment with indomethacin (10 mg/kg, intravenous) completely prevented this suppression induced by different concentrations of NaCl solutions. Intragastric administration of 1.0 M NaCl in solution caused an increase in the levels of PGE2 in the gastric lumen. Intragastric administration of OU-1308, a synthetic derivative of PGE1, also suppressed the myoelectrical activity in a dose-dependent manner. It is concluded that the suppression of gastric myoelectrical activity by hyperosmolar NaCl may be attributable to the generation of endogenous PGE2 in the stomach.

Alprostadil↗
PubMed1992

Phenylethanoid and lignan glycosides from Verbascum thapsus.

Verbascum thapsus afforded, in addition to three known phenylethanoid glycosides and four lignan ones, five new phenylethanoid glycosides and one new lignan glycoside. Structures of the compounds were elucidated by spectroscopic methods and chemical evidence.

Carbohydrate Sequence↗
PubMed1992

Triterpenoid saponins from Sophora subprostrata.

From Sophora subprostrata Radix, the roots of Sophora subprostrata, six triterpenoidal saponins having soyasapogenol A, B, sophoradiol and kuzusapogenol A as aglycones, were isolated as their methyl esters. The structure of a new saponin was established to be 3-O-[alpha-L-rhamnopyranosyl(1----2)-D-galactopyranosyl(1----2)-beta-D- glucuronopyranosyl] kuzusapogenol A methyl ester by means of 1H and 13C NMR spectroscopy and chemical evidence.

Carbohydrate Sequence↗
PubMed1992

Saponins from Trifolium repens.

From the whole plant of white clover, Trifolium repens, five new triterpenoid saponins, designated cloversaponins I-V, were isolated together with four known saponins, beta-D-glucoronopyranosylsoyasapogenol B, soyasaponin I, soyasaponin II and azukisaponin II as their methyl esters. Their structures were determined by 2H NMR and 13C NMR spectroscopy and chemical evidence.

Carbohydrate Sequence↗
PubMed1992

Effects of sialagogues on ornithine decarboxylase induction and proto-oncogene expression in murine parotid gland.

The mechanism of a sialagogue-induced increase in ornithine decarboxylase (ODC) activity and the expressions of proto-oncogenes in murine parotid gland were investigated by use of isoproterenol (IPR), carbachol (CC), and methoxamine (MTX). The results were as follows: (1) The three sialagogues had similar effects on the parotid in vivo (mouse parotid after a single injection of IPR) and/or in vitro (rat parotid explants cultured on siliconized lens paper floating on 199 medium containing IPR, CC, or MTX), the order of their effectiveness being IPR > CC > MTX. (2) Northern/dot and Western blot analyses revealed that the sialagogues elevated the steady-state levels of ODC mRNA and ODC protein to maxima at two h and six h, respectively, after stimulation. The increases were roughly proportional to those in ODC activity, suggesting that sialagogue-dependent enzyme induction is regulated at the transcriptional level. (3) The mRNAs of four of nine proto-oncogenes examined showed sialagogue-dependent increases to maxima at 30 min (c-fos) or 60 min (c-jun, c-myc, and c-src) after the beginning of stimulation. These increases were all transient, with the levels returning to the control values (without sialagogue) within 60 min. (4) The IPR-dependent elevations of ODC activity and the mRNAs of ODC, c-fos, and c-jun were inhibited by monensin, but not by polymyxin B. On the other hand, the CC-dependent increases in these parameters were inhibited by polymyxin B but not by monensin.(ABSTRACT TRUNCATED AT 250 WORDS)

Amanitins↗
PubMed1992

Inhibitory effect of taxol, a microtubule stabilizing agent, on induction of DNA synthesis is dependent upon cell lines and growth factors.

Growth-arrested rat fibroblasts, 3Y1, and human diploid fibroblasts, TIG-1, were induced to synthesize DNA by stimulation with various agents such as fetal bovine serum (FBS), epidermal growth factor (EGF), colcemid, or colchicine. Taxol, a microtubule-stabilizing agent, blocked the induction of DNA synthesis after stimulation with colcemid or colchicine in both cell lines. Taxol inhibited the induction of DNA synthesis after stimulation with FBS or EGF in TIG-1, but did not in 3Y1. 12-O-tetradecanoylphorbol-13-acetate (TPA) induced DNA synthesis in TIG-1, which was reduced only partly by taxol. Taxol stabilized or polymerized microtubules in both cell lines. These results indicate that the inhibitory effect of taxol on the induction of DNA synthesis varied among cell lines and among growth factors, and suggest that signal transduction processes may be differentiated by taxol sensitivity. In TIG-1 cells, when taxol was added within 6 h, about halfway into the initiation of DNA synthesis after the addition of FBS or EGF, the inhibition of DNA synthesis still occurred. Taxol did not inhibit the induction of c-fos and c-myc genes by FBS or EGF stimulation. Colchicine itself did not induce these genes in TIG-1. Thus, taxol appeared to inhibit the induction of DNA synthesis not by blockage in the early transduction process of the growth signal from the cell surface to nuclei but by blockage in processes operating in the mid- or late-prereplicative phase.

Alkaloids↗
PubMed1992

Studies on natural antioxidants in citrus species. I. Determination of antioxidative activities of citrus fruits.

The antioxidative activities of twenty types of citrus fruits were investigated with a screening method which is based on rat liver microsomal lipid peroxidation induced by dihydronicotinamide adenine dinucleotide phosphate (NADPH) and adenosine diphosphate (ADP). The activities of the exocarp were greater than those of the sarcocarp and the activities from immature fruits (collected in July-August) were greater than those from mature fruits. The strongest antioxidative activity was found in ponkan (Citrus reticulata Blanco) collected in July.

Animals↗
PubMed1992

Studies on differentiation-inducing activities of triterpenes.

Differentiation-inducing activity of over 180 extracts of crude drugs and plants was tested using mouse myeloid leukemia cell line (M1). The methanol extracts of clove (Syzygium aromaticum Merrill et Perry, Myrtaceae) showed remarkable induction of differentiation of M1 cells into macrophage-like cells. From the extract, oleanolic acid (1) and crategolic acid (2) were isolated as the active components. We also tested other triterpenes, such as oleananes, ursanes and dammaranes, to investigate the structure-activity relationship. Some triterpene aglycones showed differentiation-inducing activity, but triterpene glycosides showed little activity. Furthermore, the differentiation-inducing activity of these triterpene compounds was tested against human acute promyelocytic leukemia cell line (HL-60).

Animals↗
PubMed1992

[Chest wall reconstruction with a prosthetic material molded from a extirpated specimen].

A new molding technique of the Acryl-resin Marlex-mesh sandwich method is described. After the wide extirpation of the chest wall, the defect size tends to grow up more larger than the specimen. For making a just fit size prosthesis, we cut off a cardboard as the same size as the specimen and the Acryl-resin Marlex sandwich is molded from the cardboard. Other some know-how are in the text.

Acrylic Resins↗
PubMed1991

Stimulation of transcript elongation requires both the zinc finger and RNA polymerase II binding domains of human TFIIS.

The eukaryotic transcriptional factor TFIIS enhances transcript elongation by RNA polymerase II. Here we describe two functional domains in the 280 amino acid human TFIIS protein: residues within positions 100-230 are required for binding to polymerase, and residues 230-280, which form a zinc finger, are required in conjunction with the polymerase binding region for transcriptional stimulation. Interestingly, a mutant TFIIS with only the polymerase binding domain actually inhibits transcription, whereas a mutant in which the polymerase binding and zinc finger domains are separated by an octapeptide is only weakly active. The zinc finger itself has no effect on transcription, but in contrast to the wild-type protein, it binds to oligonucleotides. These findings suggest that TFIIS may interact with RNA polymerase II such that the normally masked zinc finger can specifically contact nucleotides in the transcription elongation zone at a position juxtaposed to the polymerization site.

Amino Acid Sequence↗
PubMed1991

Cloning, expression and characterization of the human transcription elongation factor, TFIIS.

The cDNA for the human elongation factor, TFIIS, has been cloned and expressed in E. coli with the T7 expression system. This 280-amino acid TFIIS protein is shorter by 21 residues than that of the mouse. The missing 21 residues are located in the amino-terminal region, which is not thought to be required for transcriptional stimulation. Apart from this gap, human and mouse proteins reveal 96% overall identity and 98.5% sequence similarity if conservative substitutions are taken into account. The bacterially expressed human protein and the purified calf thymus proteins are indistinguishable in their ability to stimulate transcript elongation by purified RNA polymerase II. Estimation of the native molecular size of the human protein in solution indicates that it exists as a dimer.

Amino Acid Sequence↗
PubMed1991

Sialagogue-stimulated protein phosphorylation related to ornithine decarboxylase induction in cultured rat parotid explants.

Both beta-adrenergic (isoproterenol) and cholinergic (carbachol) sialagogues increase amylase secretion, ornithine decarboxylase activity and DNA synthesis in murine parotid gland in vivo and in vitro. These agonists enhanced the incorporation of labelled inorganic orthophosphate into parotid proteins in rat parotid explants cultured on siliconized lens paper floating on serum-free 199 medium. Analysis of the labelled proteins by SDS-PAGE and autoradiography revealed that isoproterenol enhanced the phosphorylation of four proteins with apparent molecular weights of 17, 20, 31 and 32 kDa and carbachol stimulated the phosphorylation of 31 and 32 K proteins. Isoproterenol-dependent ornithine decarboxylase induction and phosphorylation of the proteins were selectively suppressed by monensin but not by polymyxin B, whereas carbachol-dependent ornithine decarboxylase induction and protein phosphorylation were inhibited by polymyxin B but not by monensin. Neither monensin nor polymyxin B suppressed isoproterenol- or carbachol-stimulated amylase secretion. Time course experiments showed that sialagogue-stimulated protein phosphorylation preceded the increase of ornithine decarboxylase activity and had almost disappeared when it was maximal. Propranolol and atropine, antagonists of isoproterenol and carbachol, respectively, completely inhibited not only amylase secretion and ornithine decarboxylase induction but also protein phosphorylation stimulated by the corresponding agonists. These findings suggest that increased phosphorylation of specific proteins is associated with sialagogue-stimulated ornithine decarboxylase induction but not amylase secretion.

Amylases↗
PubMed1991

Interference in the radioimmunoassay of gastric prostaglandins by cimetidine, a histamine H2 blocker.

The present study was undertaken to assess whether cimetidine alters the levels of endogenous prostaglandin (PG) E2 and 6-keto-PGF1 alpha in the rat stomach. When cimetidine was mixed in vitro with a suspension of dextran-coated charcoal, to which [3H]-PGE2 had been adsorbed, levels of free [3H]-PGE2 were increased by cimetidine at concentrations above 1.0 mM, because of preferable adsorption of this blocker to the charcoal. Dextran-coated charcoal is used for the separation of antibody-bound [3H]-PGs from the free labelled compounds in the radioimmunoassay of PGs. Addition of cimetidine to standard solutions of PGE2 shifted the PGE2 calibration curve upward. Thus, when PGs in cimetidine-containing samples were quantitated by reference to the normal calibration curve, the assessed levels of PG were lower than the actual levels. Removal of cimetidine from the assay samples was successfully achieved by use of SEP-PAK C18 columns. Rats were injected intraperitoneally with 100 mg/kg of cimetidine only once or with 20 mg/kg twice daily for 7 days. Using this cleaning method, we found that both the basal levels of PGE2 and 6-keto-PGF1 alpha and those levels increased by intragastric administration of 1.0 M NaCl solution did not differ between rats treated with cimetidine and those treated with vehicle. It can be, therefore, concluded that cimetidine does not affect the gastric PG production.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

Absence of mutagenic effects of continuous and pulsed ultrasound in cultured (AL) human-hamster hybrid cells.

Mutagenic effects of continuous and pulsed ultrasound were looked for using an in vitro assay system, the AL hybrid, that is up to 100 times more sensitive for mutagens such as x-rays and neutrons than the assays used previously to evaluate ultrasound. Cells in suspension in rotated plastic test tubes were insonated with continuous wave ultrasound at 1 MHz, ISPTP = 0.62-40 W/cm2 for 0-40 min. Cells attached in the central region of culture flasks received pulsed exposures at fc = 2.5 MHz, PRF = 1 kHz, 2 and 8 cycles per pulse, with p- = 1.2 MPa (ISPTA = 31-180 mW/cm2) for 0-30 min. Although these exposures were cytotoxic (the plating efficiency was decreased to approximately 65% by the highest doses), induction of mutation, if any occurred, was less than would be expected in this test system from 10-30 cGy of x-ray.

Animals↗
PubMed1991

Immobilized-enzyme electrode for nicotinamide adenine dinucleotide (reduced form) (NADH) sensing and application to the kinetic studies of NADH dependent dehydrogenases.

Amperometric determination of nicotinamide adenine dinucleotide (reduced form) (NADH) at an immobilized-diaphorase (Dp) electrode is described. The measurement was conducted using ferrocenylmethanol as a mediator in a stirred solution at 0.20 V versus a saturated calomel electrode. A linear relationship between the steady-state current and the concentration of NADH was found over the range 0.005-0.125 mmol dm-3. The immobilized-Dp electrode showed outstanding stability and the current response reached a steady state within 2-3 seconds upon addition of NADH. The proposed electrode was used to follow the reactions of pig heart lactate dehydrogenase and horse liver alcohol dehydrogenase. The kinetic investigation using the immobilized-Dp electrode gave the kinetic parameters (Michaelis constants, Km values, and maximum velocities, Vm values), which were in satisfactory agreement with those determined by a conventional spectrophotometric method.

Electrodes↗
PubMed1991

Efficacy of endoscopic retrograde cholecystoendoprosthesis (ERCCE) for cholecystitis.

Fourteen patients with cholecystitis were treated by endoscopic placement of an endoprosthesis into the cystic duct. In these patients the administration of antibiotics had failed to change the clinical picture of cholecystitis. Clinical and ultrasonographic findings before and two months after stenting were compared. There was an improvement in abdominal pain in 9 out of 14 cases (64%); fever, present in 5 patients, disappeared in all. No clinical complications were observed. Sonographic findings in terms of gallbladder wall thickening and sludge present within the gallbladder improved in 57% and 88%, respectively. Our results indicate that this endoscopic procedure may be effective in the treatment of cholecystitis.

Aged↗