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Biomedical subjects

S Niimi

Publications and source records attributed to S Niimi.

At least 73 records · Page 4Linked to original sources
PubMed1988

[The expression of c-myc, c-fms, c-sis oncogenes in the trophoblast of normal pregnancy and trophoblastic disease].

Recently it has been suggested that proto-oncogene plays a role not only in cellular proliferation, development and differentiation, but also in neoplastic transformation. We now show the expression and its localization of c-myc, c-fms and c-sis proto-oncogenes in human developing chorionic tissue and fresh surgical specimens of mole and choriocarcinoma with the method of Northern blotting and In-situ hybridization. The 2.4kb c-myc transcript has been localized to the cytotrophoblast in early placenta and also localized to the C and S typed trophoblastic cells in mole and choriocarcinoma. The 4.0kb c-fms transcript has been localized to the syncytiotrophoblast, especially the highly differentiated syncytiotrophoblast in the second and third trimesters and S typed trophoblastic cells in mole and choriocarcinoma. Moreover, the 4.0kb c-sis transcript has been localized to the cytotrophoblast in early placenta, but not detected in mole or choriocarcinoma. First, these results suggest that the stage and site specific expression of c-myc, c-fms and c-sis proto-oncogenes are clearly related to the proliferation, development and differentiation of normal trophoblastic cells. Second, the expression of c-myc, c-fms proto-oncogenes may be of particular importance in the tumorigenesis and progression of trophoblastic disease.

Blotting, Northern↗
PubMed1987

Multihormonal regulation of transcription of the tryptophan 2,3-dioxygenase gene in primary cultures of adult rat hepatocytes with special reference to the presence of a transcriptional protein mediating the action of glucocorticoids.

For study of hormonal regulation of gene expression of tryptophan 2,3-dioxygenase (EC 1. 13. 11. 11, TO), a DNA clone containing a sequence complementary to TO mRNA was prepared with TO mRNA from rat liver enriched 62-fold by immunoadsorption. Primary cultures of adult rat hepatocytes were treated with dexamethasone, and the amount of TO mRNA was measured by RNA dot-blot hybridization with this TO cDNA. Dexamethasone induced this TO mRNA 7-fold, while their treatments with dexamethasone plus glucagon induced the TO mRNA 18-fold. This induction of TO mRNA by dexamethasone plus glucagon was inhibited by insulin or epinephrine. Studies on transcription in isolated nuclei showed that these hormonal changes in the level of TO mRNA were caused by changes in the rate of transcription of the TO gene. Thus, expression of TO in the liver is regulated multihormonally at the transcriptional step. There was a long lag period before stimulation of transcription of the TO gene by dexamethasone in hepatocytes cultured for 20 h: the maximal rate was attained after 6-8 h. The lag time depended on the culture time without dexamethasone and was shorter after shorter culture of the cells. This finding suggested that a transcriptional factor that was lost during culture mediated the action of glucocorticoids. Consistent with this idea, cycloheximide or puromycin almost completely blocked enhanced transcription of the TO gene by dexamethasone after a 20-h culture, but not after a 2-h culture. These findings indicate that a short-lived transcriptional protein, which is also regulated by glucocorticoids, mediates their effect on expression of the TO gene.

Animals↗
PubMed1983

Hormonal regulation of translatable mRNA of glucose-6-phosphate dehydrogenase in primary cultures of adult rat hepatocytes.

The quantity of translatable mRNA of glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ 1-oxidoreductase, EC 1.1.1.49) in primary cultures of adult rat hepatocytes subjected to different hormonal conditions was determined with a reticulocyte-lysate, cell-free system. The level of glucose-6-phosphate dehydrogenase mRNA was about 5-fold higher in the presence of insulin than in its absence. This increase of glucose-6-phosphate dehydrogenase mRNA reached a maximum 12 h after the addition of insulin. The maximum level of induction of glucose-6-phosphate dehydrogenase mRNA required 10(-8) M insulin. Glucagon and triiodothyronine had no effect on the glucose-6-phosphate dehydrogenase mRNA level. The increase of glucose-6-phosphate dehydrogenase activity correlated with the increase in level of mRNA of this enzyme. This suggests that the changes in glucose-6-phosphate dehydrogenase activity in response to the above hormonal changes are primarily due to changes in the amount of mRNA coding for this enzyme.

Animals↗
PubMed1983

Hormonal regulation of translatable mRNA of tryptophan 2,3-dioxygenase in primary cultures of adult rat hepatocytes.

Tryptophan 2,3-dioxygenase [EC 1.13.11.11] in primary cultures of adult rat hepatocytes was induced 3-4 fold by 1 microM dexamethasone and 6-7 fold by dexamethasone plus glucagon (0.1 microM). Changes of the enzyme activity, amount of enzyme, measured by immunotitration, and rate of enzyme synthesis, assayed by measurement of [3H]leucine incorporation into the enzyme protein, were closely correlated. Furthermore, in a reticulocyte lysate system for cell-free protein synthesis, mRNA of the enzyme was translated to the protein corresponding to the subunit of tryptophan 2,3-dioxygenase, which was identified by SDS-polyacrylamide gel electrophoresis. The activity of translatable mRNA of the enzyme was increased more than 10-fold by dexamethasone and its final content in total mRNA was 0.34%. Glucagon alone did not increase mRNA activity, but dexamethasone plus glucagon increased mRNA activity to twice that with dexamethasone alone, the maximal content of the mRNA being 0.77% of the total mRNA content 12 h after addition of hormones. Insulin (0.1 microM) caused 75% inhibition of the maximum increase of mRNA activity of the enzyme induced by dexamethasone and glucagon. Epinephrine (10 microM) also caused 58% inhibition of the maximum increase. Insulin and epinephrine also suppressed increase of mRNA of tryptophan 2,3-dioxygenase induced by dexamethasone alone. Therefore, dexamethasone alone or together with glucagon stimulated transcription of tryptophan 2,3-dioxygenase increasing its mRNA and enzyme synthesis in hepatocytes. Conversely, insulin and epinephrine suppressed these increases of mRNA synthesis and thus decreased enzyme synthesis.

Animals↗
PubMed1981

Pharyngeal wall movement during speech.

The purpose of this study was to investigate the functional differences between the lateral walls of the mesopharynx and the epipharynx during speech. Endoscopic and electromyographic techniques were used to demonstrate the movement patterns of these two different levels of the pharyngeal wall and activities of the muscles which were supposed to induce these movements. From the movement date, it was concluded that the epipharyngeal wall contributed to the velopharyngeal closure and the mesopharyngeal wall to the vowl articulation. Electromyographic data clearly showed that the levator veli palatini muscle induced the horizontal movement of the epipharyngeal wall as well as the vertical movement of the velum. On the other hand, the superior constrictor muscle appeared to behave as one of the responsible muscles for the medial displacement of the mesopharyngeal wall.

Computers↗
PubMed1980

Rhodamine 6G, inhibitor of both H+-ejections from mitochondria energized with ATP and with respiratory substrates.

Rhodamine 6G inhibited ATP hydrolysis by oligomycin-sensitive ATPase, purified from rat liver mitochondria, in good accord with the dose-response curve for its inhibition of energy transduction of ATP synthesis in mitochondria, but it did not inhibit ATP hydrolysis by purified F1. Rhodamine 6G also inhibited both H+-ejections from mitochondria energized with respiratory substrates and with ATP. The present findings show that the inhibitory effect of rhodamine 6G on energy transduction is not due to a modification of the transport system for adenine nucleotides, Pi, and respiratory substrates, and that the inhibition sites of rhodamine 6G are on components related with H+-ejection by redox components and also on F0.

Adenosine Triphosphate↗
PubMed1980

Anisotropic inhibition of energy transduction in oxidative phosphorylation in rat liver mitochondria by tetraphenylarsonium.

Tetraphenylarsonium (TPA+) inhibited energy transduction in oxidative phosphorylation in mitochondria but not in submitochondrial particles, which are inside-out relative to the membranes of mitochondria. TPA+ incorporated into the inside of submitochondrial particles inhibited ATP synthesis in the particles. TPA+ also inhibited the reduction of NAD by succinate coupled with oxidation of succinate by O2 and hydrolysis of ATP. Energization of mitochondrial inner membranes with succinate and with ATP induced binding sites on the membranes for TPA+. The amounts of energy-dependent binding sites for TPA+ on mitochondria energized with succinate and with ATP, respectively, were 90 and 13 nmol/mg of protein. TPA+ also caused shrinkage of mitochondria energized with succinate and with ATP in an energy-dependent fashion. The energy-dependent binding of TPA+, TPA+-induced H+-ejection, TPA+-induced shrinkage of mitochondria, and TPA+-induced inhibition of energy transduction occurred in parallel. The present findings show that TPA+ inhibits energy transduction by binding to negative charges created on lipophilic domains near the surface of the outer side (C-side) of the mitochondrial inner membranes, and that it has no inhibitory activity on the inner side (M-side) of the membranes.

Adenosine Triphosphate↗
PubMed1979

A stereo-fiberscope with a magnetic interlens bridge for laryngeal observation.

A stereoscopic method of observation of the larynx and the pharynx during speech utterances has been devised, making use of fiber-optic cables and a magnetic bridge. The cables are inserted via the subject's nostrils. The bridge makes the two objective lenses at the tips of the cables abut within the pharynx near the uvula, and the two images viewed through the separate lenses at the prescribed mutual distance are recorded on each frame of a 16-mm film side by side for computer processing of the three-dimensional data.

Fiber Optic Technology↗