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Biomedical subjects

A Ueno

Publications and source records attributed to A Ueno.

At least 91 records · Page 5Linked to original sources
PubMed1998

Design of peptides undergoing self-catalytic alpha-to-beta transition and amyloidogenesis.

Improved understanding of amyloidogenic peptides and proteins such as prion proteins and Alzheimer's beta peptides has attracted much attention to the elucidation of the molecular mechanisms of such amyloidogenesis. As a representative, in the prion protein, the conformational transitions from alpha-helix to beta-structure undergo along with the amyloidogenesis in a self-catalytic manner. Moreover, recent studies by the de novo design of peptides and proteins as well as the amyloidogenesis of peptides and proteins including pathogenic protein mutants have provided insight into the conformational changes essential to amyloidogenesis and correct folding.

Amino Acid Sequence↗
PubMed1998

Purification and characterization of 9-hexadecenoic acid cis-trans isomerase from pseudomonas sp. strain E-3

A 9-hexadecenoic acid cis-trans isomerase (9-isomerase) that catalyzed the cis-to-trans isomerization of the double bond of free 9-cis-hexadecenoic acid [16:1(9c)] was purified to homogeneity from an extract of Pseudomonas sp. strain E-3 and characterized. Electrophoresis of the purified enzyme on both incompletely denaturing and denaturing polyacrylamide gels yielded a single band of a protein with a molecular mass of 80 kDa, suggesting that the isomerase is a monomeric protein of 80 kDa. The 9-isomerase, assayed with 16:1(9c) as a substrate, had a specific activity of 22.8 &mgr;mol h-1 (mg protein)-1 and a Km of 117.6 mM. The optimal pH and temperature for catalysis were approximately pH 7-8 and 30 degrees C, respectively. The 9-isomerase catalyzed the cis-to-trans conversion of a double bond at positions 9, 10, or 11, but not that of a double bond at position 6 or 7 of cis-mono-unsaturated fatty acids with carbon chain lengths of 14, 15, 16, and 17. Octadecenoic acids with a double bond at position 9 or 11 were not susceptible to isomerization. These results suggest that 9-isomerase has a strict specificity for both the position of the double bond and the chain length of the fatty acid. The enzyme catalyzed the cis-to-trans isomerization of fatty acids in a free form, and in the presence of a membrane fraction it was also able to isomerize 16:1(9c) esterified to phosphatidylethanolamine. The 9-isomerase was strongly inhibited by catecholic antioxidants such as alpha-tocopherol and nordihydroguaiaretic acid, but was not inhibited by 1, 10-phenanthroline or EDTA or under anoxic conditions. Based on these results, the possible mechanism of catalysis by this enzyme is discussed.

Journal Article↗
PubMed1998

Analysis of mutant quantity and quality in human-hamster hybrid AL and AL-179 cells exposed to 137Cs-gamma or HZE-Fe ions.

We measured the number of mutants and the kinds of mutations induced by 137Cs-gamma and by HZE-Fe (56Fe [600 MeV/amu, LET = 190 KeV/micrometer) in standard AL human hamster hybrid cells and in a new variant hybrid, AL-179. We found that HZE-Fe was more mutagenic than 137Cs-gamma per unit dose (about 1.6 fold), but was slightly less mutagenic per mean lethal dose, DO, at both the S1 and hprt- loci of AL cells. On the other hand, HZE-Fe induced about nine fold more complex S1- mutants than 137Cs-gamma rays, 28% vs 3%. 137Cs-gamma rays induced about twice as many S1- mutants and hprt-mutants in AL-179 as in AL cells, and about nine times more of the former were complex, and potentially unstable kinds of mutations.

Animals↗
PubMed1998

Putrescine-stimulated intracellular Ca2+ release for invasiveness of rat ascites hepatoma cells.

Our previous study showed that treatment of highly invasive rat ascites hepatoma (LC-AH) cells with alpha-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase, decreased both their intracellular level of putrescine and their in vitro invasion of a monolayer of calf pulmonary arterial endothelial (CPAE) cells, and that both these decreases were completely reversed by exogenous putrescine, but not spermidine or spermine. Here we show that all adhering control (DFMO-untreated) cells migrated beneath CPAE monolayer with morphological change from round to cauliflower-shaped cells (migratory cells). DFMO treatment increased the number of cells that remained round without migration (nonmigratory cells). Exogenous putrescine, but not spermidine or spermine, induced transformation of all nonmigratory cells to migratory cells with a concomitant increase in their intracellular Ca2+ level, [Ca2+]i. The putrescine-induced increase in their [Ca2+]i preceded their transformation and these effects of putrescine were not affected by antagonists of the voltage-gated Ca2+ channel, but were completely suppressed by ryanodine, which also suppressed the invasiveness of the control cells. The DFMO-induced decreases in both [Ca2+]i and the invasiveness of the cells were restored by thapsigargin, which elevated [Ca2+]i by inhibiting endoplasmic Ca2+-ATPase, indicating that thapsigargin mimics the effects of putrescine. These results support the idea that putrescine is a cofactor for Ca2+ release through the Ca2+ channel in the endoplasmic reticulum that is inhibited by ryanodine, this release being initiated by cell adhesion and being a prerequisite for tumor cell invasion.

Animals↗
PubMed1998

Cloning of TCFL5 encoding a novel human basic helix-loop-helix motif protein that is specifically expressed in primary spermatocytes at the pachytene stage.

We have isolated a novel human gene that is expressed specifically in primary spermatocytes in the testis. The cDNA contains an open reading frame of 1356 bp, encoding a 452-amino-acid protein that includes a basic Helix-Loop-Helix (bHLH) motif. The gene, which was mapped to chromosome region 20q13.3-->qter by fluorescence in situ hybridization, consists of six exons and spans approximately 24 kb of genomic DNA. Immunohistochemical staining located the gene product exclusively in cell nuclei of primary spermatocytes at the pachytene stage, but not in those at the leptonema stage. We named this gene TCFL5 (transcription factor-like 5, basic helix-loop-helix). The cell-type and stage-specific expression of TCFL5 indicates that this protein may function in a crucial role in spermatogenesis as a transcription factor by regulating cell proliferation or differentiation of cells through binding to a specific DNA sequence like other bHLH molecules.

Animals↗
PubMed1998

Mouse paw edema induced by a novel bradykinin agonist and its inhibition by B2-antagonists.

A novel non-peptide bradykinin B2-receptor agonist, FR190997 (8-[2,6-dichloro-3-[N-[(E)4-(N-methylcarbamoyl)cinnamidoacetyl+ ++]-N-methylamino]benzyloxy]-2-methyl-4-(2-pyridylmethoxy)quinolin e), induced dose-dependent and longer-lasting swelling than bradykinin in the mouse paw. The swelling, peaking around 30 min, was suppressed dose-dependently by intraperitoneal administration of FR173657, a novel non-peptide B2-receptor antagonist. A known B2-antagonist, Hoe 140, also significantly suppressed this edema. The result indicates that the novel B2-agonist FR190997, being more stable than bradykinin, could induce plasma exudation locally in mice via the B2-receptor as a substitute for bradykinin.

Animals↗
PubMed1998

Morphological studies of glomeruli in obstructive kidneys by confocal laser scanning microscopy and quick-freezing replica method.

Morphological changes of glomeruli in obstructive kidneys were studied by using confocal laser scanning microscopy (CLSM), and quick-freezing and deep-etching (QF-DE) method. Twenty-one rabbits were divided into three groups, consisting of control, 6-hr bilateral ureteral obstruction (BUO) and 24-hr BUO. In the experimental groups, the attenuation of cell bodies, the lengthening and stretching of major processes, the cystic formation in the cytoplasm and the fusion of foot processes were observed on conventional ultrathin sections. These changes in the 24-hr BUO group were more clearly observed than those in the 6-hr BUO group. By the CLSM, cell bodies and foot processes of podocytes in the experimental groups were more intensely immunostained with anti-alpha-tubulin antibody and phalloidin-FITC. By the QF-DE method, cytoskeletons in the podocyte cell bodies and major processes were composed of numerous intermediate filaments, but distinct changes of actin filaments and microtubules were not observed in the control and experimental groups. Considering the physiological changes in BUO, the mechanical stress appeared to be brought about by hemodynamic factors rather than the change of intratubular pressure, resembling the morphological changes in experimental animals with hyperfiltration and the homeostatic adaptation of podocytes under the BUO condition.

Animals↗
PubMed1997

Inhibition of osteoblastic cell differentiation by conditioned medium derived from the human prostatic cancer cell line PC-3 in vitro.

Human prostatic carcinoma frequently metastasizes to bone tissue and activates bone metabolism, especially bone formation, at the site of metastasis. It has been reported that an extract of prostatic carcinoma and conditioned medium (CM) of a human prostatic carcinoma cell line, PC-3, established from a bone metastastic lesion, stimulate osteoblastic cell proliferation. However, there is little information about the effect of PC-3 CM on the differentiation of osteoblastic cells. In this study, we investigated the effect of PC-3 CM on the differentiation of two types of osteoblastic cells, primary fetal rat calvaria (RC) cells containing many undifferentiated osteoprogenitor cells, and ROS 17/2.8, a well-differentiated rat osteosarcoma cell line. PC-3 CM inhibited bone nodule formation and the activity of alkaline phosphatase (ALPase), an osteoblastic marker enzyme, on days 7, 14, and 21 (RC cells) or 3, 6, and 9 (ROS 17/2.8 cells) in a dose-dependent manner (5-30% CM). However, the CM did not affect cell proliferation or cell viability. PC-3 CM was found to markedly block the gene expression of ALPase and osteocalcin (OCN) mRNAs but had no effect on the mRNA expression of osteopontin (OPN), the latter two being noncollagenous proteins related to bone matrix mineralization. These findings suggest that PC-3 CM contains a factor that inhibits osteoblastic cell differentiation and that this factor may be involved in the process of bone metastasis from prostatic carcinoma.

Alkaline Phosphatase↗
PubMed1997

Altered pain perception and inflammatory response in mice lacking prostacyclin receptor.

Prostanoids are a group of bioactive lipids working as local mediators and include D, E, F and I types of prostaglandins (PGs) and thromboxanes. Prostacyclin (PGI2) acts on platelets and blood vessels to inhibit platelet aggregation and to cause vasodilatation, and is thought to be important for vascular homeostasis. Aspirin-like drugs, including indomethacin, which inhibit prostanoid biosynthesis, suppress fever, inflammatory swelling and pain, and interfere with female reproduction, suggesting that prostanoids are involved in these processes, although it is not clear which prostanoid is the endogenous mediator of a particular process. Prostanoids act on seven-transmembrane-domain receptors which are selective for each type. Here we disrupt the gene for the prostacyclin receptor in mice by using homologous recombination. The receptor-deficient mice are viable, reproductive and normotensive. However, their susceptibility to thrombosis is increased, and their inflammatory and pain responses are reduced to the levels observed in indomethacin-treated wild-type mice. Our results establish that prostacyclin is an antithrombotic agent in vivo and provide evidence for its role as a mediator of inflammation and pain.

Animals↗
PubMed1997

Identification and characterization of receptor for cytokine-induced neutrophil chemoattractant-3 on rat neutrophils.

Cytokine-induced neutrophil chemoattractants (CINCs), members of alpha-chemokines, are considered to be major neutrophil chemotactic factors in rats. Recombinant CINC-3/rat macrophage inflammatory protein-2 (MIP-2) having an additional tyrosine residue at the carboxyl terminus (CINC-3-Tyr) was constructed, purified, radiolabeled with 125I, and used for binding studies. The specific binding of 125I-labeled CINC-3-Tyr (125I-CINC-3-Tyr) to rat neutrophils reached a plateau after approximately 60 min at 4 degrees C. This binding of 125I-CINC-3-Tyr could be reversed by adding an excess amount of unlabeled CINC-3-Tyr. Scatchard analysis revealed approximately 12,000 binding sites per cell on rat neutrophils with an apparent Kd value of 120 pM. Chemical cross-linking experiments suggested that the rat neutrophil CINC-3 receptor is a mass of approximately 69 kDa. Taken together, our results strongly suggest that rat neutrophils express a high affinity receptor for CINC-3.

Animals↗
PubMed1997

Concordant induction of prostaglandin E2 synthase with cyclooxygenase-2 leads to preferred production of prostaglandin E2 over thromboxane and prostaglandin D2 in lipopolysaccharide-stimulated rat peritoneal macrophages.

Rat peritoneal macrophages were stimulated with lipopolysaccaride (LPS) for various periods and their ability to convert exogenous arachidonic acid to various prostanoids was examined. Unstimulated cells, which expressed cyclooxygenase (COX)-1 but not COX-2, produced thromboxane (TX) B2 > prostaglandin (PG) D2 > PGE2, whereas cells stimulated for 6-12 h with LPS exhibited marked increase in conversion to PGE2, which paralleled COX-2 induction, with minimal change in conversion to TXB2 and PGD2. Pharmacological studies showed that formation of PGE2 was mediated predominantly by COX-2, PGD2 by COX-1, and TXB2 by both COX-1 and COX-2 depending upon the timing of LPS stimulation. Measurement of the conversion of exogenous PGH2 to each prostanoid in cell lysates demonstrated LPS-dependent increase in PGE2 synthase activity that was degenerated by pretreatment with actinomycin D or cycloheximide. Thus, concordant induction of terminal PGE2 synthase with COX-2 leads to the preferred production of PGE2 to TXB2 and PGD2 by LPS-stimulated macrophages.

Animals↗
PubMed1997

Potentiating effect of buserelin acetate, an LHRH agonist, on the proliferation of ventral prostatic epithelial cells in testosterone-treated castrated rats.

BACKGROUND: We used buserelin acetate ([D-Ser(But)6] LHRH ), an LHRH agonist and strong blocker of LH secretion, as a treatment for prostatic cancer. It is possible that this LHRH agonist has a proliferative effect on the prostate in addition to suppressing LH secretion. The purpose of this study was to examine the proliferative effect of LHRH agonist on rat prostatic epithelial cells. METHODS: We determined the optimal dose of testosterone necessary to maintain a positive level of proliferating cell nuclear antigen (PCNA) in the ventral prostatic epithelial cells of castrated Wistar rats. Testosterone-treated rats then received various doses of buserelin acetate. Castrated rats without exogenous testosterone also received buserelin acetate. The PCNA positivity was determined by immunohistochemistry with anti-PCNA monoclonal antibody. RESULTS: The optimal dose of testosterone enanthate was 4 mg at 0 and 28 days after castration. Administration of buserelin acetate on day 0 and 28 in doses of 0.16 mg to 1.28 mg significantly increased PCNA positivity in a dose-dependent manner. Administration of buserelin acetate to castrated rats without testosterone also increased PCNA positivity but there was no statistical significance. CONCLUSIONS: Buserelin acetate has a potentiating effect on the proliferation of ventral prostatic epithelial cells of castrated rat in the presence of a physiological level of exogenous testosterone. This effect may slightly influence the result of hormonal therapy by LHRH agonist.

Animals↗
PubMed1997

Psychotropic drugs and local anesthetics restore cardiolipin-inhibited mammalian DNA topoisomerase I activity.

The activity of mammalian topoisomerase I is inhibited by acidic phospholipids. We investigated the effect of psychotropic drugs and local anesthetics on cardiolipin-inhibited calf thymus DNA topoisomerase I activity. Chlorpromazine, promethazine, and imipramine, which interact with phospholipids, suppressed the inhibitory effect of cardiolipin. The present results suggest that relaxation of DNA supercoiling is involved in the cytotoxic action of these drugs.

Anesthetics, Local↗
PubMed1997

[Induction of bradykinin B1 receptor in rats].

We found the time-dependent induction of the systemic hypotensive response to des-Arg9-bradykinin and the contractile response of ileum of rats to des-Arg9-bradykinin. Both induced responses to des-Arg9-bradykinin were inhibited by treatment with a B1 receptor competitive antagonist, while the responses to bradykinin was constant throughout the experiment and was not influenced by the B1 antagonist, suggesting that these responses occur via a B1 receptor. The potencies of des-Arg9-bradykinin in these responses were comparable to those of bradykinin at a molar base. The other characteristics of this phenomenon is that several hours were required to the induction of these responses. In a case of hypotensive response, intravenous LPS pretreatment was necessary, but not for the induction of contraction in ileum preparation. Treatment with actinomycin D or cycloheximide throughout the experiment suppressed the induction of the contractile response to des-Arg9-bradykinin. The expression of B1 receptor gene was also confirmed by a RT-PCR method. Therefore, we concluded that these responses to des-Arg9-bradykinin occurred via a B1 receptor, which could be newly generated time-dependently.

Animals↗
PubMed1997

Effects of ONO-2235, an aldose reductase inhibitor, on muscarinic receptors and contractile response of the urinary bladder in rats with streptozotocin-induced diabetes.

This study was conducted to evaluate effects of the aldose reductase inhibitor ONO-2235 on the contractile response to acetylcholine of the urinary bladder dome of streptozotocin-induced diabetes mellitus (DM) rats and simultaneously observe the changes in the function and number of muscarinic receptors and the sorbitol content of the bladder. The contractile response to acetylcholine increased 51% in the DM rat bladder dome compared to the normal rats; however, this was attenuated to a 10% increase by administration of 100 mg/kg ONO-2235 for 2 weeks. Treatment with ONO-2235 significantly decreased the specific [3H]quinuclidinyl benzilate binding in DM rats. However there was no significant dose-dependency among the ONO-2235-treated groups. The sorbitol levels of the sciatic nerve and the bladder were higher in the DM rats compared to the control rats; ONO-2235 decreased the level, although it did not completely reverse them to the control level. These results suggest that an aldose reductase inhibitor attenuates the increase of the muscarinic receptor number and normalizes the enhanced contractile response to acetylcholine caused by hyperglycemia and diuresis, probably through suppression of the polyol-pathway in the DM rat bladder dome.

Acetylcholine↗
PubMed1997

An analysis of the effects of nitroglycerin on forearm circumference, with simultaneous recordings of arterial and venous diameters and blood pressure.

The aim of this study is to define the effect of sublingually administered nitroglycerin (NTG) on the diameters of the forearm arteries and veins as well as to define the relationship between these vascular changes and the forearm circumference in healthy volunteers. For this purpose, we employed a noninvasive method permitting the simultaneous quantitative recording of vascular diameters, forearm circumference and blood pressure using a miniature load cell, linear differential transformers and mercury-in-rubber strain gauge. Sublingually administered NTG (0.3 mg) increased the radial arterial diameter and the forearm circumference, whereas the cephalic vein capacitance was decreased; consequently, the cephalic vein acts to moderate the increase in forearm circumference. The results clearly indicate that nitroglycerin dilates forearm arteries but not forearm veins in the normal state.

Adult↗
PubMed1997

Detection of viral RNA by electron microscopic in situ hybridization (ISH-EM) in the germinal epithelium of mice infected with encephalomyocarditis (EMC) virus.

Electron microscopic in situ hybridization (ISH-EM) was first applied to the detection of viral RNA in the germinal epithelium of mice inoculated i.p. with 10(5) plaque-forming units/mouse of the D variant of encephalomyocarditis virus (EMC-D). Signals of viral RNA were first detected in a small number of Sertoli cells showing mild degeneration at 2 days post inoculation, and 2 days later, they were also detected in germinal cells and spermatogonia when Sertoli cells showed prominent degeneration. The results clearly demonstrated that the first site of viral attack in the germinal epithelium was Sertoli cell in the case of EMC-D-induced mouse orchitis.

Animals↗