PubMed Health⌕ Search

Biomedical subjects

A Isobe

Publications and source records attributed to A Isobe.

At least 19 recordsLinked to original sources
PubMed2006

Involvement of Sp-1 in the regulation of the Id-1 gene during trophoblast cell differentiation.

Id-1, a member of the helix-loop-helix transcription factor family, inhibits the differentiation of Rcho-1 cells, which were derived from rat choriocarcinoma and consist of trophoblast stem cells. Id-1 is expressed at a high level in undifferentiated trophoblast stem cells and then down-regulated during early differentiation, and is thought to be a key regulator in the trophoblast giant-cell differentiation pathway. In this study, we analyzed the signaling mechanism regulating the high expression levels of Id-1 in undifferentiated Rcho-1 cells. Promoter deletion analysis revealed that a 31-bp sequence (Box-2 region), located between -200 and -169bp in the Id-1 promoter is necessary for the promoter activity. Electrophoretic mobility shift assays and DNA affinity precipitation assays showed that Box-2-binding activity was decreased during differentiation and that Sp-1 protein bound to this sequence. The protein level of Sp-1 was decreased during the differentiation. These results suggest that the Sp-1 protein level may regulate the Box-2-binding activity and the trophoblast giant-cell differentiation.

Animals↗
PubMed2005

STAT3-mediated constitutive expression of SOCS3 in an undifferentiated rat trophoblast-like cell line.

In the trophoblast, constitutive expression of SOCS3 is important for the negative regulation of trophoblast giant cell differentiation. In this study, we analyzed the signaling pathway regulating the constitutive SOCS3 expression in undifferentiated Rcho-1 cells, which were derived from rat choriocarcinoma and consist of trophoblast stem cells that are capable of differentiating to trophoblast giant cells in vitro. PD98059, an MEK inhibitor, repressed the SOCS3 expression but AG490, a JAK2 inhibitor, did not. Promoter deletion analysis revealed that the STAT response element (SRE) in the SOCS3 promoter is necessary for the promoter activity. Overexpression of STAT3 increased the SOCS3 promoter activity, whereas expression of dominant-negative STAT3 reduced it. Constitutive STAT3 tyrosine phosphorylation that was not inhibited by either AG490 or PD98059 was demonstrated. Electrophoretic mobility shift assays showed the existence of a protein that bound to SRE and was supershifted with STAT3 antibody. This binding reaction was inhibited by neither AG490 nor PD98059. These findings imply that the ERK/MAPK pathway and STAT3 are involved in the constitutive activation of SOCS3 in undifferentiated Rcho-1 cells. Moreover, they indicate that the constitutive STAT3 tyrosine phosphorylation and the DNA binding activity of STAT3 do not depend on the ERK/MAPK or JAK kinase pathway. These results suggest that a trophoblast-specific STAT3 activation pathway is important for the regulation of giant cell differentiation.

Animals↗
PubMed2001

Ras/MAP kinase pathway is associated with the control of myotube formation but not myofibril assembly in quail myoblasts transformed with Rous sarcoma virus.

Tyrosine kinase activity of v-Src from Rous sarcoma virus (RSV) inhibits the differentiation of quail myoblasts. To clarify the inhibitory mechanism, we focused on the signaling pathways from v-Src. When the activation of the Ras/MAP (mitogen-activated protein) kinase pathway was inhibited by a dominant-negative mutant of Ras or PD98059, a specific inhibitor of p42 MAP kinase kinase, differentiation was restored; muscle specific proteins were expressed and myotubes formed even under active conditions of v-Src. Wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase (P13-kinase), showed no effects on the inhibition by v-Src. These findings suggest that v-Src activates the Ras/MAP kinase signaling pathway, but not the P13-kinase pathway, and inhibits the differentiation. However, the myotubes derived from the dominant-negative Ras did not form actin fibers, suggesting that myofibril assembly is regulated by other pathway(s) from v-Src.

Animals↗
PubMed2000

Structural features for fluorescing present in methoxycoumarin derivatives.

Structural features of fluorescent methoxycoumarins were examined from the viewpoint of substituent effect and ring structure in connection with intramolecular charge-transfer (ICT). The fluorescence of methoxycoumarins depended primarily upon the ICT from a C6-electron-donating group to the substituents at the C3-position of the coumarin ring. Furthermore, the presence of a lactone ring itself, including a carbonyl group, cyclic ether oxygen and ethylenic bond as partial ring structures, was found to be essential for fluorescing in methoxycoumarins according to the fluorescent behaviors of chemically deformed model compounds.

Chemical Phenomena↗
PubMed2000

Effect of temperature on fatty acid composition in each lipid fraction of Spirometra erinaceieuropaei plerocercoids.

The effects of temperature and host fatty acids on the fatty acid contents of Spirometra erinaceieuropaei plerocercoids were investigated to clarify their role in sparganosis. After 24 hr incubation at 18 C in host snake serum, omega6 series fatty acids, especially arachidonic acid in the phospholipid fraction of the plerocercoids, increased compared with those of plerocercoids incubated at 37 C. The changes in the ratio of polyunsaturated to saturated fatty acids in the phospholipid fraction of plerocercoids incubated in physiological saline for 6 hr at 10 C were almost the same as the changes at 37 C. The ratio of polyunsaturated to saturated fatty acids of the triglyceride fraction showed almost opposite change versus the phospholipid fraction. The percentage of arachidonic acid in the phospholipid fraction of plerocercoids increased during the first 3 hr of incubation and then decreased, regardless of temperature. At 37 C, the percentage of arachidonic acid in the free fatty acid fraction fell for the first 3 hr of incubation and was significantly elevated at the end of the 6-hr incubation. At 10 C, however, arachidonic acid in the free fatty acid fraction decreased for the first hour of incubation, increased at 3 hr of incubation, then decreased again. These results suggest that fatty acids of the plerocercoids are frequently exchanged between fractions. Plerocercoids can mobilize arachidonic acid to the free fatty acid fraction more quickly at lower temperature than at higher temperature. They may utilize mobilized arachidonic acid early in the infection stage to produce prostaglandins. Alternatively, they can incorporate arachidonic acid into the phospholipid fraction again when arachidonic acid is readily available in the environment.

Animals↗
PubMed1999

Food intake, serum lipids and amino acids of school children in agricultural communities in Japan.

OBJECTIVE: To investigate the correlation among serum lipids, amino acids and diet of children in Japan where the mortality of ischemic heart disease is still very low. DESIGN: Cross-sectional study. SETTING: Two towns in Shimane prefecture, typical mountainous agricultural communities in the western part of the mainland of Japan. SUBJECTS: 514 children (10-15 y) in the communities were recruited. RESULTS: The mean cholesterol levels ranged from 3.9 to 4.4 mmol/l for boys and from 4.3 to 4.5 mmol/l for girls, and serum cholesterol level fell with age in boys. Serum cholesterol level of girls rose once between 11 and 13 y and fell gradually. Fish intake was positively correlated with serum omega-3 series fatty acids. Milk intake was negatively and soybean intake was positively correlated with omega-3/omega-6 series fatty acids ratio. Serum branched-chain amino acids were correlated negatively with serum polyunsaturated/saturated fatty acids ratio. CONCLUSIONS: Serum cholesterol level of children in agricultural communities in Japan has risen, and is probably affected by the change of food intake. Promoting the intake of soybean and fish, which are traditional Japanese foods, will be important in preventing atherosclerosis and ischemic heart disease. Attention should be paid to the relationship between branched-chain amino acids level in blood and fatty acids metabolism to verify the mechanism of the progress of atherosclerosis.

Adolescent↗
PubMed1999

Medical education in China for the 21st century.

Drastic changes are occurring in medical education around the world. Medicine and medical technologies are developing rapidly and expanding beyond the multidisciplinary area. The needs of medical care and medical education are different even from those of several years ago. In order to cope with these increasing social needs, the innovation of medical education in China has become an urgent and important problem. This study is an attempt to answer the question of how to develop medical education in China for the 21st century, based on a historical review of the development of medical education. This development might be divided into three periods: (1) before the Cultural Revolution; (2) the Cultural Revolution (1966-76); and (3) post-Cultural Revolution (1977-present) in modern China, and based on problem analysis of the curriculum, teaching methods, education evaluation, systems and policies and the balance between educational needs and supplies. We concentrate on the discussion of how to solve these problems, and have designed a new strategy for the further development of medical education in China. This discussion and newly developing strategy focuses on the main targets and priorities and adoption of suitable measures according to the conditions of the country. The purposes are to elevate the quality of medical education, to train qualified doctors to meet continuously increasing needs and to maintain the development of medical education for the 21st century in China.

China↗
PubMed1999

Inflammatory action of 8-methoxypsoralen-spermine photoproduct (8-MOP-Spm-P(GFC)) and effects of various drugs on rat paw edema induced by 8-MOP-Spm-P(GFC).

The photoproducts produced by irradiating 8-methoxypsoralen (8-MOP) in the presence of spermine (Spm) were fractionated using gel filtration chromatography (GFC) on a Sephadex G-25 column. As a result, two bands which were characterized by the effects on hyaluronidase activity were obtained. The first band strongly activated the hyaluronidase, but a second band did not exhibit any effect on the enzyme activity. The first and second bands contained photoproducts with molecular weights (MW)>2700 and MW<728, respectively, determined by the GFC method. The photoproducts, 8-MOP-Spm-P(GFC) obtained from the first band, but not the photoproducts with lower MW from the second band, showed enzyme activating action. 8-MOP-Spm-P(GFC) induced paw edema, which was stronger in the first phase than the second one in rats, differing from that induced by carrageenin. This photoproduct was a substance with lower cell toxicity because it did not cause hemolysis on red blood cells or the release of lactic dehydrogenase from mast cells in rats. The effects of various drugs on 8-MOP-Spm-P(GFC)-induced edema were investigated. As a result, edema formation was inhibited by drugs with an anti-histaminic action, such as alimemazine, dl-chlorpheniramine, promethazine, ketotifen and azelastine, and with anti-serotonin action such as cyproheptadine. On the other hand, tranilast did not show significant inhibition and indomethacin showed a tendency to increase its formation. These results suggested that 8-MOP-Spm-P(GFC) is a new inflammatory substance and is very useful as an agent to develop new anti-inflammatory drugs without cyclooxygenase inhibitory action.

Animals↗
PubMed1998

Effect of serum fatty acid composition on coronary atherosclerosis in Japan.

The serum lipid profiles of patient's with or without significant coronary stenosis diagnosed by coronary angiography and of control subjects were compared. The level of high-density-lipoprotein cholesterol and eicosapentaenoic acid were significantly lower in the patients with significant coronary stenosis than in the control subjects. It suggests that high-density-lipoprotein cholesterol and omega3 fatty acids may have a protective effect on the progress of coronary atherosclerosis. The frequency of eating dark-meat fish was positively associated with serum eicosapentaenoic acid and docosahexaenoic acid, omega3 fatty acids, and inversely associated with serum stearic acid and linoleic acid. The frequency of eating soybean products was positively associated with serum docosahexaenoic acid and inversely associated with serum linoleic acid. It is necessary to discuss a way to popularise a diet of dark-meat fish and soybean products as a means of preventing coronary heart disease.

Aged↗
PubMed1998

A Trp 64 Arg mutation in the beta3-adrenergic receptor gene is not associated with moderate overweight in Japanese workers.

The aim of the present study was to investigate the trend for obesity and the relationship between Trp64Arg mutation in the beta3-adrenergic receptor gene and obesity-related phenotypes in Japanese workers. A total of 658 workers, 483 women and 175 men, responded to this survey. Genomic DNA was prepared from leukocytes, and DNA amplification by polymerase chain reaction was performed using 100 ng genomic DNA. Amplified fragments were digested with BstNI and analyzed by 3% agarose gel electrophoresis. The body mass index (BMI) increased from 21.1 +/- 2.6 to 22.0 +/- 3.0 kg/m2 for women and from 20.9 +/- 2.1 to 22.1 +/- 2.6 kg/m2 for men from 1982 to 1997. Body weight increased 63.3% for women and 67.4% for men over 15 years. The frequency of the Trp64Arg allele was 19.9%, and the frequency of heterozygote and homozygote carriers of the mutation was 32.9% and 3.4%, respectively. Changes in the BMI and body weight over 15 years from 1982 to 1997 did not differ significantly between subjects with or without the mutant allele in either women or men. The BMI was not significantly higher in subjects who were homozygous or heterozygous for the Trp64Arg mutation versus subjects who were homozygous for the normal allele. This mutation of the beta3-adrenergic receptor gene is not likely a major determinant of moderate obesity in the Japanese population.

Adult↗
PubMed1998

Characterization of myogenin expression in myotubes derived from quail myoblasts transformed with a temperature sensitive mutant of Rous sarcoma virus.

During myogenic differentiation of quail myoblasts transformed with a temperature sensitive mutant of Rous sarcoma virus (QM-RSV cells), it was observed that myogenin was continuously expressed in myotubes. In contrast, in myotubes derived from quail primary cells (parent cells of QM-RSV cells), myogenin expression was seen only in the myotubes not having striated structures comprised of myofibrils, but not in myotubes having the structures. The fact that there are not striated structures of myofibrils formed in myotubes derived from QM-RSV cells suggests that these myotubes stop at an immature state prior to the final differentiation. These results also suggest that myogenin is not only required for early steps during differentiation but also maturation steps of myotubes. To clarify the roles of myogenin after myotube formation and maturation, myotubes derived from QM-RSV cells were treated with N,N'-hexamethylene bisacetamide (HMBA) or incubated at 35.5 degrees C, a permissive temperature of RSV for suppression of myogenin expression. On treatment with HMBA, myogenin expression disappeared and myotubes began to incorporate 5-bromo-2'-deoxyuridine (BrdU) into the nuclei, whereas the expression remained in many myotubes on culture at 35.5 degrees C. These results suggest that immature myotubes can return to an up step of differentiation, prior to the commitment step with HMBA treatment, but not with culture at 35.5 degrees C.

Acetamides↗
PubMed1998

Evaluation of propolis (II): effects of Brazilian and Chinese propolis on histamine release from rat peritoneal mast cells induced by compound 48/80 and concanavalin A.

To establish a biological method for evaluating propolis and to reveal their anti-allergic action, the effects of the ethanol and water extracts (EA-ET and WA-WT, respectively) from Brazilian, Chinese and Japanese propolis on the histamine release induced by compound 48/80 and concanavalin A (Con A) were investigated. The relation between the inhibitory activities of these extracts on the histamine release and their E(1 cm)1% values were also examined. As a result, the following was found: 1) 0.003-0.01% ethanol and 0.03-0.1% water extracts inhibited the histamine release induced by compound 48/80 and Con A, and the inhibitory potencies of the former extracts were more than 10 times stronger than those of the latter extracts, making it clear that both the ethanol and water extracts possess an anti-allergic action; 2) most of the ethanol and water extracts responded to the histamine release induced by both the histamine releasers in a concentration-dependent manner; 3) the inhibitory activities of 0.003% EM from Hebei Province, EP from Sichuan Province, EQ from Zhejiang Province and ER from Anhui Province in China were weaker than those of 0.01% corresponding extracts, whereas 0.001% ED-EH from Brazilian propolis, EM, EN from Henan Province in China and EP-ER promoted the Con A-induced histamine release of more than 10%, suggesting that such extracts must be carefully given to humans; 4) the inhibitory potencies of only 0.03-0.1% water extracts from Chinese propolis on the Con A-induced histamine release related excellently with their E(1 cm)1% values; 5) from the results of the relation between the inhibitory potencies of the propolis extracts and their E(1 cm)1% values, it was suggested that an unknown compound, being a poorly water-soluble compound which is a non-flavonoid, with an anti-allergic action is contained in propolis; 6) to precisely evaluate the anti-allergic action of the propolis, the biological method, which measures the inhibitory activities of the propolis extracts on histamine release, was markedly superior to the physicochemical method.

Animals↗
PubMed1998

Arachidonic acid metabolism to prostaglandin E2, D2, F2alpha, and I2 in the plerocercoid of Spirometra erinaceieuropaei.

Changes in the fatty acid composition of phospholipid and triglyceride fractions in Spirometra erinaceieuropaei plerocercoids were investigated after 0, 0.5, 1, 3, and 6 hr incubation at 10 C and 37 C with physiological saline containing 5 mM arachidonic acid and 10 mg/ml bovine serum albumin, pH 7.0. At 37 C, arachidonic acid was absorbed and incorporated rapidly into the triglyceride fraction (over 14.4% in composition), and decreased after 2-3 hr; at 10 C, the amount of triglyceride increased slowly and continued to a maximum of 12.9% during 6 hr of incubation. We used a simplified method to extract and purify prostaglandins from the plerocercoid of S. erinaceieuropaei. Prostaglandins were quantified using gas chromatography-mass spectrometry. Prostaglandin E2, PGD2, PGF2alpha, and 6-keto-PGF1alpha were detected under different incubation conditions. In the dose-dependent experiment, PGD2 was detected in plerocercoids incubated with 0.5, 1, 2, and 5 mM arachidonic acid, pH 7.0, at 25 C; PGE2 was detected with 2 and 5 mM arachidonic acid. In the time-dependent experiment, where plerocercoids were incubated with 5 mM arachidonic acid, pH 7.0 at 25 C, PGF2alpha was first detected at 15 min; thereafter, 6-keto-PGF1alpha was detected at 30 min and PGD2 and PGE2 were detected at 1 hr. Thromboxane B2 was not detected in either the dose-dependent or time-dependent experiments, and only PGE2 was detected in the incubation medium with 5 mM arachidonic acid at 1 hr. These results reveal that when plerocercoids change from reptilian to mammalian hosts, they are able to absorb and modify arachidonic acid bound to albumin and generate prostaglandins under suitable conditions. Prostaglandins exhibit potent biological functions for immunoresponses that may be relevant to parasitism and the success of larva migrans in S. erinaceieuropaei.

Animals↗
PubMed1997

Inhibitory effect of nicotinamide to paraquat toxicity and the reaction site on complex I.

The inhibitory effect and mechanism of action of nicotinamide to paraquat toxicity were studied in male Sprague-Dawley rats. Proteins of submitochondrial particles (SMP), especially of mol. wt. 25-30 kDa, in rat lungs were destroyed by paraquat radicals, and aggregated protein bands approximately 100 kDa were observed by polyacrylamide electrophoresis. The competitive inhibition effects were observed of nicotinamide on NADH oxidation by paraquat via SMP in rat lungs and the Ki was 9.3 mM. The inhibitory effects of nicotinamide on lipid peroxidation by paraquat with rat lung and liver SMP were verified. The times of occurrence of dyspnea and death in rats after paraquat exposure were delayed by nicotinamide administration. The activity of NADH: ubiquinone reaction of NADH:ubiquinone oxidoreductase (complex I) in rat lung was reduced 24 h after paraquat exposure, and was protected by nicotinamide. The activity of NADH:ferricyanide reaction of complex I was, however, reduced by administration not only of paraquat but also nicotinamide. These results imply that nicotinamide is inhibitory to paraquat toxicity. Nicotinamide, paraquat, and ferricyanide may react at overlapping sites on complex I.

Animals↗
PubMed1997

Effects of organophosphorous compounds on fatty acid compositions and oxidative phosphorylation system in the brain of rats.

Effects of organophosphorous compounds, O,O-dimethyl O-4-nitro-m-tolyl phosphorothioate (MEP), O-ethyl O-p-nitrophenyl phenylphosphonothioate (EPN) and O-(4-cyanophenyl) O-ethyl phenylphosphonothioate (CYP), on the fatty acid composition and the subsequent effects on the oxidative phosphorylation system in the brain of rats were studied. After 6 days exposure in pesticides, polyunsaturated fatty acids in brain free fatty acid fractions of CYP treated rats decreased, and the unsaturation index in them were lower than those in the control rats. The polyunsaturated/saturated ratio (P/S ratio) in brain total lipids of CYP treated rats was lower than that in the control. The fatty acid composition in the brain of EPN treated rats had the same inclination as that of CYP treated rats. In the P/S ratio and unsaturation index in serum no difference was observed between CYP treated rats and the control, therefore CYP could affect the fatty acid composition in the rat brain directly. Free fatty acid contents in the brain of EPN and CYP treated rats decreased after 6 days exposure. Activities of complex I of brains were significantly higher in the EPN and CYP exposed rats than in the control rats in spite of the fact that no difference of ATP productivity was observed between them. These results suggest that EPN and CYP may affect the free fatty acid content, especially the polyunsaturated fatty acid content and consequently the enzyme activities in the oxidative phosphorylation system in the brain. Those phenomena, however, were not observed after 28 days exposure in pesticide, therefore those effects may be a passing phenomenon in an acute stage.

Animals↗
PubMed1997

Children's smoking habits in an agricultural community in Japan and the importance of a no smoking program integrating family, school and community health.

The object of this study is to establish a model of integration of the health promotion projects which have been planned separately by schools and communities so far in an agricultural area in Japan, to solve the problem of children's smoking. The subjects of the study were 10-15 y old schoolchildren and their parents. The questionnaires were completed by the children themselves at school and also by their parents at home, in July 1995. One fourth of the junior high school boys had ever tried smoking, while most of their parents did not notice that their children were smoking. More than half of the children who had ever tried smoking mainly acquired tobacco from their homes. One tenth of them were prompted to smoke by their fathers or other relatives. To develop a health promotion project for children which includes prevention of smoking, the provision of a health education program and an environment which encourages health are important for children. The project should also be community-based because participation of local inhabitants in the project gives it additional impetus. In order to promote the comprehensive health of children, we emphasize the importance of setting up a healthy district plan based on the health policy of the general community.

Adolescent↗
PubMed1997

Myogenin expression is necessary for commitment to differentiation and is closely related to src tyrosine kinase activity in quail myoblasts transformed with Rous sarcoma virus.

Quail myoblasts transformed with a temperature-sensitive mutant of Rous sarcoma virus (QM-RSV cells) proliferate at 35.5 degrees C, a permissive temperature for RSV, but differentiate at 41 degrees C, a nonpermissive temperature, with the formation of multinucleated myotubes and the synthesis of muscle-specific proteins. Tyrosine kinase activity of the src gene product derived from RSV is closely related to regulation of this temperature-dependent differentiation, and the cells obtain commitment to differentiation by incubation for about 12 h at 41 degrees C with dephosphorylation of tyrosine-phosphorylated protein(s). It was examined how myogenin, a member of myogenic regulatory factors, participates in commitment to differentiation and tyrosine dephosphorylation of QM-RSV cells. Myogenin was expressed within 8 h and reached a plateau within 10 h at 41 degrees C. Each cell clone whose differentiation proceeded faster or slower than the parental QM-RSV cells was reflected by a faster or slower myogenin expression, corresponding to the time that is required for commitment to differentiation. It was suggested that there is a lag time between myogenin expression and the acquisition of commitment in QM-RSV cells. On the other hand, at 35.5 degrees C, a condition which suppresses differentiation, myogenin expression was not detected. However, herbimycin A, an inhibitor of protein tyrosine kinase, induced myogenin expression even at 35.5 degrees C. On the contrary, myogenin expression was inhibited at 41 degrees C by sodium orthovanadate, an inhibitor of tyrosine-phosphorylated protein phosphatase. Furthermore, forced induction of myogenin into the cells cultured at 35.5 degrees C resulted in the formation of multinucleated myotubes and the synthesis of muscle-specific proteins. These results suggest that myogenin expression is one of the indispensable conditions for the acquisition of commitment to differentiation and is regulated by tyrosine phosphorylation and dephosphorylation of some protein(s) in QM-RSV cells.

Animals↗