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T Sekimoto

Publications and source records attributed to T Sekimoto.

54 records · Page 3Linked to original sources
PubMed1983

A possible regulatory role of Ca++-calmodulin system in cellular cholesterol ester hydrolysis in the steroidogenic response to ACTH in bovine adrenocortical cells.

In order to corroborate the regulatory role of Ca++-calmodulin system in the steroidogenic response to adrenocorticotropic hormone (ACTH), the effects of calmodulin inhibitors (chlorpromazine, trifluoperazine, and W-7) on cortisol production and cellular cholesterol ester hydrolysis induced by ACTH in bovine adrenocortical cells were examined. Three calmodulin inhibitors diminished not only the cholesterol ester hydrolysis and cortisol production induced by ACTH in the presence of Ca++, but also inhibited the Ca++-induced hydrolysis and cortisol production in the absence of ACTH. Neither cortisol production in crude mitochondrial fraction nor the ACTH-induced Ca++-influx was affected by chlorpromazine. These results indicate that Ca++f-calmodulin system plays a significant regulatory role in the supply of free cholesterol to the adrenal mitochondria in the steroidogenic response to ACTH.

Adrenal Cortex↗
PubMed1975

Measurement of right ventricular volumes using 131I-MAA.

A method has been presented for determining the right ventricular residual ratio, that is, the ratio of the end-systolic volume to the end-diastolic volume during each cardiac cycle. 131I-MAA was injected as a bolus into the right ventricle, and the ratio of isotope remaining in the chamber during the succeeding cardiac cycles was determined with a collimated scintillation counter placed over the right ventricle. Since the counter detected the radioactivity from the entire right ventricular cavity, potential errors from incomplete mixing were minimized. The washout curve from the ventricle was distorted somewhat by the accumulation of isotope in intervening lung tissue. This distortion was eliminated by subtracting the build-up curve of radioactivity in the lung recorded simultaneously with a second scintillation counter positioned over the lateral chest wall. In 14 dogs anesthetized with chloralose, the right ventricular residual ratio was relatively constant at 40.4 plus or minus 3.1 per cent. Duplicate measurements differed by less than 3 per cent indicating the good reproducibility of the method. Right ventricular stroke volume was determined from cardiac output (dye dilution) and heart rate. With this and the simultaneously determined residual ratio (131I-MAA), end-diastolic volume could be calculated. Stroke volume and stroke work were highly correlated with end-diastolic volume, in keeping with the Frank-Starling mechanism.

Animals↗
PubMed1974

A new method for measurement of right ventricular residual ratio using 121I-MAA.

A new technique of precordial counting with 131I-MAA for measurement of right ventricular residual ratio (RVRR) was described. 131I-MAA was rapidly injected injected into the right ventricle at the time of right heart catheterization. The fraction of isotope discharged from this chamber per beat was determined with a crystal detector with tapered collimator which was pointed to the center of right ventricle. The radioisotope dilution curve was corrected by using the lung built up curve recorded by the other detector pointed to the lung field. Then, the right ventricular end-systolic volume (ESV) and the right ventricular end-diastolic volume (EDV) were calculated from the RVRR and stroke volume. In 6 patients with normal hemodynamics, the RVRR averaged 57.8 plus or minus 4.9%, the ESV 52.2 plus or minus 13.6 ml/M(2) and the EDV 89.4 plus or minus 15.1 ml/M(2). In 16 patients with heart diseases, the RVRR averaged 60.6 plus or minus 7.1%, the ESV 80.6 plus or minus 34.0 ml/M(2) and the EDV 127.2 plus or minus 43.6 ml/M(2). In 11 patients with chronic pulmonary diseases, the RVRR averaged 70.7 plus or minus 9.9%, the ESV 94.7 plus or minus 42.4 ml/M(2) and the EDV 133.0 plus or minus 46.5 ml/M(2). The RVRR in the last group increased significantly.

Adolescent↗
PubMedDate not supplied

Nuclear import and export of proteins: the molecular basis for intracellular signaling.

A family of latent cytoplasmic transcription factors termed Stats are activated by a variety of cytokines, and are then translocated into the nucleus where they activate transcription. Recent advances in nuclear protein import have shown that the extracellular signal-dependent nuclear import of Stat1 is mediated via complex formation with NPI-1 (a member of the alpha subunit family) and the beta subunit of the nuclear pore-targeting complex, and a small GTPase, Ran. The unique transport pathway of Stat1, which is different from that of the SV40T-antigen, indicates that a complex divergence exists in the function of transport factors and transport pathways.

Animals↗
PubMedDate not supplied

Effect of cutting instruments on permeability and morphology of the dentin surface.

There are major differences in morphological detail after cutting the dentin surface among the methods commonly used to prepare dental cavities. The purpose of this study was to compare dentin permeability and the morphology of the dentin surfaces prepared with diamond and carbide steel burs after etching with 6% citric acid. Twenty-four freshly extracted human third molars were sectioned, mounted on plexiglass, and connected to the dentin-permeability measuring apparatus. The permeability of dentin was measured by fluid filtration and expressed as hydraulic conductance. There were two study groups of 12 teeth. Each tooth had one occlusal cavity preparation prepared but utilized three depths: the original was prepared just into the dentin, the second 0.5 mm deeper than the first, and the third 0.5 mm deeper than the second. One group had the first cavity prepared with a diamond, the second deepened using a steel bur, then the third depth was made by use of the diamond. The other group had the first cavity preparation prepared with a steel bur, deepened 0.5 mm again using a diamond, then deepened again using a steel bur. Dentin permeability was measured after cavity preparation, then after 2 minutes of acid etching. Analysis of variance and Duncan's multiple range test were used to establish whether differences were significant at the 0.05 confidence level. Prepared and acid-etched surfaces were characterized using a scanning electron microscope to identify any differences between the two groups. After acid etching with 6% citric acid, the permeability of dentin cavities prepared with diamond burs was significantly less than the permeability of cavities prepared with carbide steel burs. After etching, there were differences in the appearance of the dentin surfaces prepared with diamonds and steel burs. Dentin bonding agents may have their effectiveness reduced when placed following cavity preparation by use of a diamond.

Dental Bonding↗