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T Seki

Publications and source records attributed to T Seki.

At least 181 records · Page 10Linked to original sources
PubMed1999

[Study of transforming growth factor-alpha expression in duodenal ulcer].

Various growth factors were also reported to promote healing of peptic ulcer. We have used a monoclonal antibody in conjunction with a standard immunohistochemical technique to characterize the expression of transforming growth factor-alpha (TGF-alpha) in duodenal ulcer. TGF-alpha immunoreactivity is found in Brunner's gland, also in immature gland and in duodenal epitheliums, but not in gastric metaplasia of the duodenum. TGF-alpha expression of healing and scar stage was higher than that of active stage. The presence or absence of Helicobacter pylori infection did not affect the expression of TGF-alpha in duodenal ulcer.

Adult↗
PubMed1999

[Renin-angiotensin-aldosterone system in the reproductive system].

Besides the circulating renin-angiotensin-aldosterone (R-A-A) system, the tissue R-A-A system has been elucidated to play important roles as autocrines and/or paracrines. The components of R-A-A system are expressed in the ovary, uterus and placenta, indicating the existence of the tissue R-A-A system in these organs. The data indicating the involvement of R-A-A system of these tissues into reproduction have been accumulated. AT2 receptors might modulate the initiation and progression of follicle atresia involving granulosa cell apoptosis. AT2 receptors are expressed abundantly in the uterus and decreased during pregnancy. The placental renin are shown to be secreted into the maternal circulation and elevate blood pressure. It is expected to elucidate the significance of the R-A-A system in the reproductive system.

Animals↗
PubMed1999

Preliminary investigation of resistance of plasmid DNA to neon ion beams using transformation into recipient Escherichia coli cells.

The sensitivity of the vector plasmid pKmK8 DNA to neon ion beams was studied under dry conditions. This plasmid contains the cloning vector pJKKmf(-) and a 3.6 kbp segment encoding the Escherichia coli crp gene that can be used in mutagenesis analysis. The survival curve of the plasmid indicated an exponential profile and a D10 value of about 16 kGy in the E. coli wild-type strain for DNA repair capability. This was similar to the D10 value for the shuttle vector plasmid pZ189 DNA. Therefore, it was assumed that the excision repair system in E. coli was not effective for repairing DNA lesions induced by irradiation with heavy ion beams.

DNA Damage↗
PubMed1999

[Hippocampal adult neurogenesis and neuronal circuit formation: an analysis with special reference to polysialic acid-neural cell adhesion molecule].

It is generally thought that neurons are generated during the embryonic and early postnatal periods, but not in the adult. However, as neurogenesis continues in the dentate granule layer of the adult hippocampal formation, this would imply that new neuronal circuits are being added to the adult hippocampus by adult neurogenesis. Since these newly generated granule cells specifically express polysialic acid (PSA)-neural cell adhesion molecule (NCAM), it is possible to examine the new neuronal circuit formed by these cells using PSA immunohistochemisty. As for PSA function, it has been shown that the PSA expression of the mossy fibers is required for synaptic arrangement. Recently neurogenesis and PSA expression in the adult hippocampus are reported to be affected by neuronal activity and hormones, suggesting that they are closely associated with hippocampal plasticity.

Animals↗
PubMed1999

[Arylamidase].

Explore the source record for details and available documents.

Aminopeptidases↗
PubMed1999

[Geobotanical studies on the island of Tanegashima (affinity of world property island Yakushima)].

A list was drawn up of wild plants growing on Tanegashiama island that were identified in our field work, and the list was compared with the flora of the rest of Japan and the flora of Taiwan. There were 166 families and 1,218 species consisting of 23 families and 159 species of Pteridophyta, 4 families and 7 species of Gymnosperma, 113 families and 700 species of the dicotyledous Angiosperma, and 26 families and 353 species of monocotyledous Angiosperma. There are 229 families and 5,500 species of plants in Japan, 196 families and 3,019 species in Kyushu, and 228 families and 3,477 species in Taiwan. There are 11 species of endemic plants on Tanegashima and Yakushima, and the best known of them is Pinus armandii Francht. var. amamiana Hatsushima. There are 181 species of flora of flora limited to the northern element, including several important medicinal plants, such as Akebia quinata Decaisne and Zanthoxylum piperitum DC. The 69 species of flora limited to the southern element include several important tropical plants, such as Messerschmidia argentea Johnston and Clerodendrum inerme Gaertn. Most of these plants are distributed on both island, but some of are distributed only Tanegashima. We concluded that one of the temperate borderlines of Japanese flora in the temperate zone is the islands of Tokara. The flora of Tanegashima and Yakushima are having a closely affinity of plant species and having the rich plant species.

Botany↗
PubMed1998

Cloning of two isoforms of mouse DNA helicase Q1/RecQL cDNA; alpha form is expressed ubiquitously and beta form specifically in the testis.

We cloned cDNAs encoding mouse homologues for the human DNA helicase Q1/RecQL (human helicase Q1) which has homology with the Escherichia coli RecQ protein and found that they encode two isoforms. The two isoforms are identical over the entire sequence except for the carboxyl terminal sequence spanning less than 30 amino acids. One of the two isoforms, alpha, contains a sequence, KKRK, in the carboxyl terminus, which is also contained in human helicase Q1 and was confirmed to function as the nuclear localization signal. The other form, beta, does not contain such a sequence. Expression of mouse helicase Q1 mRNA is extremely and relatively high in the testis and the thymus, respectively. RT-PCR analysis revealed that helicase Q1alpha was expressed in all tissues tested and the beta form was expressed only in the testis. A survey of expression of Q1alpha and Q1beta mRNA in the testis after birth revealed that Q1alpha mRNA is expressed in all testes of mice aged from 7 days to 8 weeks, and the expression of Q1beta mRNA begins 14 days after birth, corresponding to the appearance of cells in the pachytene stage.

Amino Acid Sequence↗
PubMed1998

Cloning of cDNA encoding a novel mouse DNA topoisomerase III (Topo IIIbeta) possessing negatively supercoiled DNA relaxing activity, whose message is highly expressed in the testis.

We cloned cDNA encoding a novel mouse homologue of DNA topoisomerase III (mTOP3beta). The nucleotide sequence contains an open reading frame of 863 amino acids, and the deduced molecular mass of the coded protein is 96.9 kDa. The overall sequence of mTOP3beta has a 48 and 36% identity with mouse TOP3alpha at the nucleotide and amino acid level, respectively. DNA topoisomerase IIIbeta was expressed using a baculovirus expression system and purified. The purified DNA topoisomerase IIIbeta had activity to relax negatively supercoiled DNA. Relaxation of supercoiled DNA was partial at 37 degreesC and complete relaxation was observed at higher temperatures. mTOP3beta mRNA was strongly expressed in the testis and relatively strongly in the brain. The levels of TOP3beta mRNA in the testis increased slightly 14 days and considerably 17 days after birth, when the cells in the pachytene phase begin to appear and increase.

Amino Acid Sequence↗
PubMed1998

The metabolic pathway of visual pigment chromophore formation in Drosophila melanogaster--all-trans (3S)-3-hydroxyretinal is formed from all-trans retinal via (3R)-3-hydroxyretinal in the dark.

Carotenoid-depleted fruit flies, Drosophila melanogaster, were reared on yeast/glucose medium containing lipid-depleted white corn grits and cholesterol. After rearing for more than a year, the yield of flies remained constant and the content of 3-hydroxyretinal in a head was three logarithmic units less than that of normal flies reared on medium containing yellow corn grits. When all-trans retinal was supplied as the sole source of retinoids, the flies formed and accumulated all-trans 3-hydroxyretinal in the dark. To examine the metabolic pathway to produce (3S)-3-hydroxyretinal in Drosophila, all-trans retinal was supplemented for two hours to carotenoid-depleted flies in the dark, and the subsequent changes in the composition of 3-hydroxyretinal enantiomers were analyzed using a chiral column on HPLC. The results indicated initial formation of (3R)-3-hydroxyretinal followed by isomerization into the 3S enantiomer. In another set of experiments, the membrane fraction was obtained from the head homogenate of retinoid-depleted flies and an in vitro assay of 3-hydroxyretinal formation from retinal was performed. The 3-hydroxyretinal produced was the 3R enantiomer, supporting the result obtained from the in vivo experiment whereby (3S)-3-hydroxyretinal is produced from retinal via (3R)-3-hydroxyretinal. Addition of NADPH enhanced 3-hydroxyretinal formation and the presence of carbon monoxide inhibited it, suggesting that hydroxylation at the C3 position of retinal occurred via the monooxygenase activity of cytochrome P-450.

Animals↗
PubMed1998

Carbachol inhibition of Ca2+ currents in ventricular cells obtained from neonatal and adult rats.

We investigated the postnatal developmental changes produced by the muscarinic receptor agonist, carbachol, on the L-type Ca2+ current (ICa(L)) in neonatal (aged 5 to 7 days) and adult (aged 2 to 5 months) rat ventricular cells by using the whole-cell voltage clamp technique. Carbachol inhibited the isoproterenol-stimulated ICa(L). The maximal inhibition was 89.3 +/- 4.8% (n = 5) in neonatal cells and 17.7 +/- 7.7% (n = 9) in adult cells. Carbachol inhibited the forskolin-stimulated ICa(L) to almost same extent as the isoproterenol-stimulated ICa(L). In the cells pretreated with pertussis toxin, carbachol failed to inhibit the isoproterenol-stimulated ICa(L), indicating that carbachol produced its effect via a pertussis toxin-sensitive G-protein pathway. The effects of carbachol in adult cells became more pronounced, increasing from 17.7% to 54.8% (n = 11), with the addition of the synthetic inhibitory G-protein alpha subunit (Gi alpha) (1 microM) to the reaction. Conversely, the alpha subunit of another pertussis toxin-sensitive synthetic G-protein (G(o) alpha, 1 microM) failed to mimic the effect of Gi alpha. These results suggest that, in rat ventricular cells, (1) the action of carbachol on ICa(L) showed a marked decrease during development; (2) the decrease in the effect of carbachol in adult cells is in part due to a decrease in the activity of pertussis toxin-sensitive G protein, especially Gi alpha.

Animals↗
PubMed1998

High susceptibility of p53(+/-) knockout mice in N-butyl-N-(4-hydroxybutyl)nitrosamine urinary bladder carcinogenesis and lack of frequent mutation in residual allele.

The loss of p53 functions is considered to compromise the growth-suppression machinery of the cell and facilitate neoplastic change. In humans, genetic alteration in the p53 gene is one of the most frequently observed molecular changes in tumors, including urinary bladder carcinomas. We have investigated the susceptibility of heterozygote p53 knockout mice to N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in terms of urinary bladder tumor induction. Both p53(+/-) knockout mice and C57BL/6 original parent strain were administered 0, 0.002, 0.004, 0.0075 and 0.025% BBN in the drinking water for 20 weeks. As compared with the C57BL/6 strain, greater lesion yields were observed in knockout mice after 20 weeks of treatment. Transitional cell carcinomas were found in 9 (75%) and 12 (100%) of each 12 mice of the 0.0075 and 0.025% BBN treatment groups, respectively, whereas only 1 (11%) and 6 (67%) of each 9 of the C57BL/6 mice demonstrated tumors. Preneoplastic lesions (dysplasia) were also observed more frequently in the lower dose groups in the knockout mice than C57BL/6 mice. PCR single-strand conformation polymorphism analysis followed by DNA direct sequencing of the p53 gene (exons 5-8) extracted from bladder tumors demonstrated mutations in 3 of 11 (27.3%; exon 7) and 8 of 29 (27.6%; exons 5-8) tumors in C57BL/6 and knockout mice, respectively. There was no significant difference in the mutation rates at the residual p53 gene between the two cases. All mutations observed in knockout mice were restricted to the normal allele, and none were present in the gene-targeted null allele. In a separate experiment, 5-bromo-2'-deoxyuridine labeling indices after treatment with BBN for 2 or 4 weeks were significantly higher in knockout mice than wild-type mice. Measurement of the urinary concentration of N-butyl-N-(3-carboxypropyl)nitrosamine, a proximate carcinogenic metabolite, revealed no significant differences between knockout and original parent strain after administration of 0.0075% BBN in the drinking water for 4 weeks. In conclusion, knockout mice are distinctly more sensitive to urinary bladder carcinogenesis induced by BBN than their original parent strain, as evidenced by elevated DNA synthesis during carcinogen administration and an increased tumor yield. The high susceptibility of p53 knockout mice appeared to be related to the high level of cell proliferation rather than that of N-butyl-N-(3-carboxypropyl)nitrosamine in the urine or that of mutations at the p53 gene.

Alleles↗
PubMed1998

cDNA cloning of mouse BLM gene, the homologue to human Bloom's syndrome gene, which is highly expressed in the testis at the mRNA level.

We cloned a cDNA encoding the mouse homologue to human Bloom's syndrome gene (BLM). The deduced amino acid sequence of mouse Blm showed 76% identity to the human sequence with very high homology in seven consecutive domains characteristic of DNA and RNA helicases. The expression of mBLM mRNA was examined in various tissues. Extremely high expression was observed in the testis as compared with other tissues. The mBLM mRNA level in the testis began to increase 12-14 days after birth, corresponding to the appearance of cells in the pachytene phase.

Adenosine Triphosphatases↗
PubMed1998

Metabolism analysis and on-line physiological state diagnosis of acetone-butanol fermentation.

Fermentation equations for acetone-butanol (AB) were applied in a metabolic analysis of the reaction network under various conditions; that is, at different pHs and a high NADH2 turnover rate using methyl viologen, in a Clostridium acetobutylicum culture. The results disclosed variations in the pattern of rate changes that reflected changes in the physiological state. A linear relationship was found to exist between NADH2 generation and butanol production rate. By coupling an automated measurement system with the fermentation model, on-line estimation of the culture state was accomplished. Based on the AB fermentation model, new parameters were defined for on-line diagnosis of the physiological state and determination of the best timing for amplifying NADH2 generation by the addition of methyl viologen to obtain a high level of butanol productivity. A potential means of achieving optimal control for a high level of solvent production, involving the correlation of certain rates, is proposed.

Acetone↗
PubMed1998

Beta-adrenoceptor antagonist propranolol potentiates hypotensive action of natriuretic peptides.

Beta-adrenoceptor antagonists are known to increase plasma atrial natriuretic peptide (ANP) levels despite their hypotensive action. The aim of the present study was to examine the role of the ANP system in the antihypertensive effects of a beta-adrenoceptor antagonist. We investigated the effects of propranolol (75 mg kg(-1) day(-1), p.o., 4 weeks) on the ANP system in stroke-prone spontaneously hypertensive rats. Plasma ANP levels were significantly higher in the propranolol group than in the control group. Both receptor densities and mRNA levels of ANP(C) receptor were significantly decreased in the lung as the major site of ANP clearance from the circulation. In contrast, both central venous pressure and ANP mRNA levels in the heart were not significantly different between the two groups. Under both basal and ANP-stimulated conditions, the cGMP content in the aorta was significantly greater in the propranolol group than in the control group, whereas the basal and stimulated cGMP content of the kidney was similar in the two groups. Inhibition of endogenous ANP action by a specific ANP receptor antagonist, HS-142-1, produced a greater increase of blood pressure in the propranolol group than in the control group. These results suggest potentiation of natriuretic peptide activity as a new antihypertensive mechanism of the beta-adrenoceptor antagonist propranolol.

Adrenergic beta-Antagonists↗
PubMed1998

DAMGO recognizes four residues in the third extracellular loop to discriminate between mu- and kappa-opioid receptors.

Previously, we reported that replacement of the region from the fifth transmembrane domain to the C-terminus of kappa-opioid receptor with the corresponding region of mu-opioid receptor gives high affinity for [D-Ala2, N-MePhe4, Gly-ol5]enkephalin (DAMGO), a mu-opioid receptor-selective ligand, to the resultant chimeric receptor, suggesting that the difference in the amino acid sequence within this region is critical for the discrimination between mu- and kappa-opioid receptors by DAMGO. In the present study, we constructed further six mu/kappa-chimeric receptors and revealed that at least two separate regions around the third extracellular loop are critical for the discrimination between mu- and kappa-opioid receptors by DAMGO. Furthermore, we constructed several mutant receptors by a site-directed mutagenesis technique and found that the difference between Glu297 of kappa-opioid receptor and Lys303 of mu-opioid receptor in one region, and the difference between Ser310, Tyr312 and Tyr313 of kappa-opioid receptor and Val316, Trp318 and His319 of mu-opioid receptor in the other region, are critical for the discrimination between these receptors by DAMGO. The mutant receptor, kappa (E297K + Y313H + Y312W + S310V), in which the Glu297, Ser310, Tyr312 and Tyr313 of kappa-opioid receptor were changed to Lys, Val, Trp and His, respectively, bound to DAMGO with high affinity (Kd = 8.7 +/- 1.2 nM) and efficiently mediated the inhibitory effect of DAMGO on intracellular cAMP accumulation. The present results showed that these four amino acid residues act as determinants for the discrimination between mu- and kappa-opioid receptors by DAMGO.

Adenylyl Cyclases↗