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Biomedical subjects

H Ishimoto

Publications and source records attributed to H Ishimoto.

51 records · Page 3Linked to original sources
PubMed1992

Thromboxane A2 receptor characterization in human astrocytoma cells and rabbit platelets by a new thromboxane antagonist, [3H]ONO NT-126.

Thromboxane A2 receptors of human astrocytoma cells and rabbit platelets were characterized by a binding of a new potent and selective thromboxane A2 antagonist, [3H]ONO NT-126. [3H]ONO NT-126 bound with a high affinity to membranes derived from astrocytoma cells and platelets. In astrocytoma cells, the nonspecific binding determined by 1 microM S-145 was observed in high percentage to total binding. Scatchard plots of both membranes were linear, expressing a single binding site with the Kd of 0.17 nM and Bmax of 46.4 fmol/mg protein in astrocytoma cell membranes and with the Kd of 0.28 nM and Bmax of 1585 fmol/mg protein in platelet membranes, respectively. [3H]ONO NT-126 binding was displaced most potently by ONO NT-126 among other thromboxane A2 analogues. [3H]ONO NT-126 binding was displaced by ONO NT-126, S-145, SQ29548, STA2 and U46619 with Ki values (nM) of 0.21, 1.14, 7.05, 23.5 and 235 in astrocytoma cell membranes and 0.23, 5.55, 259, 9.25 and 43.7 in platelet membranes, respectively. The characteristics of TXA2 receptors apparently differ in rabbit platelets and human astrocytoma cells.

Animals↗
PubMed1991

Trifluoperazine inhibits phosphoinositide hydrolysis as a histamine H1-receptor antagonist.

In human astrocytoma cells (1321N1), trifluoperazine potently inhibited histamine-induced phosphoinositide hydrolysis, while it slightly inhibited carbachol-induced phosphoinositide hydrolysis. Trifluoperazine as well as diphenhydramine inhibited [3H]mepyramine binding in astrocytoma cell membranes with Ki values of 0.052 microM and 0.005 microM, respectively. However, trifluoperazine only slightly inhibited [3H]quinuclidinyl benzilate binding with a Ki value of 3 microM. These results indicate that trifluoperazine specifically inhibits histamine-induced phosphoinositide hydrolysis as a histamine H1-receptor antagonist in human astrocytoma cells.

Astrocytoma↗
PubMed1991

[The effect of immediate delivery on the fetus with reverse end-diastolic flow velocity in umbilical artery velocimetry].

Reverse end-diastolic flow velocity suggests a catastrophic fetal condition. Some authors have suggested that perinatal management of these pregnancies should be more aggressive. Despite increased opportunities to use Doppler ultrasonography, guidelines for clinical management of such pregnancies have not been established. We have applied immediate delivery to 6 patients out of 7 patients who showed reverse end-diastolic flow velocity. When the study population was compared with the population of the other authors, there were no differences in gestational age at diagnosis, birth weight, or incidence of maternal hypertension. However, the study patients were delivered at significantly higher Apgar scores and had a lower perinatal mortality rate. These results suggest that immediate delivery of the fetus with reverse end-diastolic flow may be correlated with a favorable perinatal outcome.

Blood Flow Velocity↗
PubMedDate not supplied

Single-molecule magnets: a new class of tetranuclear manganese magnets.

The preparation, X-ray structure, and detailed physical characterization are presented for a new type of single-molecule magnet [Mn4(O2CMe)2(pdmH)6](ClO4)2 (1). Complex 1.2MeCN.Et2O crystallizes in the triclinic space group P1, with cell dimensions at 130 K of a = 11.914(3) A, b = 15.347(4) A, c = 9.660(3) A, alpha = 104.58(1) degree, beta = 93.42(1) degree, gamma = 106.06(1) degree, and Z = 1. The cation lies on an inversion center and consists of a planar Mn4 rhombus that is mixed-valent, MnIII2MnII2. The pdmH- ligands (pdmH2 is pyridine-2,6-dimethanol) function as either bidentate or tridentate ligands. The bridging between Mn atoms is established by either a deprotonated oxygen atom of a pdmH- ligand or an acetate ligand. The solvated complex readily loses all acetonitrile and ether solvate molecules to give complex 1, which with time becomes hydrated to give 1.2.5H2O. Direct current and alternating current magnetic susceptibility data are given for 1 and 1.2.5H2O and indicate that the desolvated complex has a S = 8 ground state, whereas the hydrated 1.2.5H2O has a S = 9 ground state. Ferromagnetic interactions between MnIII-MnII and MnIII-MnIII pairs result in parallel spin alignments of the S = 5/2 MnII and S = 2 MnIII ions. High-frequency EPR spectra were run for complex 1.2.5H2O at frequencies of 218, 328, and 436 GHz in the 4.5-30 K range. A magnetic-field-oriented polycrystallite sample was employed. Fine structure is clearly seen in this parallel-field EPR spectrum. The transition fields were least-squares-fit to give g = 1.99, D = -0.451 K, and B4 degrees = 2.94 x 10(-5) K for the S = 9 ground state of 1.2.5H2O. A molecule with a large-spin ground state with D < 0 can function as a single-molecule magnet, as detected by techniques such as ac magnetic susceptibility. Out-of-phase ac signals (chi'' M) were seen for complexes 1 and 1.2.5H2O to show that these complexes are single-molecule magnets. A sample of 1 was studied by ac susceptibility in the 0.4-6.4 K range with the ac field oscillating at frequencies in the 1.1-1000 Hz range. A single peak in chi'' M vs temperature plots was seen for each frequency; the temperature of the chi'' M peak varies from 2.03 K at 995 Hz to 1.16 K at 1.1 Hz. Magnetization relaxation rates were evaluated in this way. An Arrhenius plot gave an activation energy of 17.3 K, which, as expected, is less than the 22.4 K value calculated for the thermodynamic barrier for magnetization direction reversal for an S = 8 complex with D = -0.35 K. The 1.2.5H2O complex with an S = 9 ground state has its chi'' M peaks at higher temperatures.

Journal Article↗
PubMedDate not supplied

MR imaging of non-CNS fetal abnormalities: a pictorial essay.

The recent popularity of prenatal magnetic resonance (MR) imaging has been associated with the development of ultrafast MR imaging techniques such as the single-shot fast spin-echo sequence. However, the majority of previous reports have concerned the fetal central nervous system (CNS) and chest disorders. MR imaging can demonstrate non-CNS fetal anatomy and pathologic conditions clearly. With its excellent tissue contrast, MR imaging provides information that supplements that provided by ultrasonography (US), especially in cases of neck, chest, and gastrointestinal lesions. Because of its large field of view, MR imaging allows evaluation of the relationship between a large lesion and adjacent structures. MR imaging should be considered if the diagnosis of a suspected non-CNS lesion is unclear at fetal US. MR imaging plays an important complementary role to US in cases of non-CNS fetal lesions and will be further accepted for fetal imaging in the future.

Abdomen↗
PubMedDate not supplied

Prediction of smallness for gestational age by maternal serum human chorionic gonadotropin levels and by uterine artery Doppler study.

OBJECTIVES: To compare the utility of maternal serum human chorionic gonadotropin (MShCG) levels with that of uterine artery Doppler study in predicting small for gestational age (SGA) birth and pregnancy-induced hypertension (PIH). METHODS: MShCG assay and uterine artery Doppler study were performed in 359 consecutive pregnant women with singleton pregnancies. MShCG levels > or =2.0 multiples of the median at 15-18 weeks' gestation were considered to be elevated. An abnormal uterine artery Doppler velocimetry at 21-24 weeks' gestation was defined as a mean pulsatility index above the 95th percentile or the presence of an early diastolic notch in either uterine artery. The predictive values of MShCG levels and uterine artery Doppler velocimetry were evaluated for the risk of SGA birth and PIH. RESULTS: Forty-one subjects gave birth to SGA infants, and 20 developed PIH. Patients with MShCG elevation or abnormal uterine artery Doppler velocimetry showed a significantly higher incidence of SGA infants than the controls. The sensitivity and specificity of MShCG elevation for SGA birth were 17.1 and 93.4%, respectively, compared with abnormal uterine artery Doppler velocimetry, which had 24.4 and 94.3%, respectively. There was no significant difference between these methods. Elevated levels of MShCG and abnormal uterine artery Doppler velocimetry were not associated with PIH. CONCLUSION: Elevated levels of second-trimester MShCG were as sensitive and specific in predicting SGA births as abnormal uterine artery Doppler velocimetry.

Arteries↗