Biomedical subjects

S Okada

Publications and source records attributed to S Okada.

At least 307 records · Page 17Linked to original sources

PubMed1999

[Digoxin Reference Standard (Control 991) of National Institute of Health Sciences].

The raw material of digoxin was examined to prepare a "Digoxin Reference Standard". The analytical data obtained were: optical rotation, [alpha](20)D = + 11.7 degree; loss on drying, 0.008%, infrared spectrum, the same as that of the Digoxin Reference Standard (Control 807); high-performance liquid chromatography, several impurities detected and the total amount estimated to be about 0.31%, assay by spectrophotometry, 100.1%. Based on the above results, the candidate material was authorized as the Digoxin Reference Standard (Control 991) of the National Institute of Health Sciences.

Digoxin↗

PubMed1999

[Lanatoside C Reference Standard (Control 981) of National Institute of Health Sciences].

The raw material of lanatoside C was examined for preparation of the "Lanatoside C Reference Standard". The analytical data obtained were: melting point, 247.4 degree C; optical rotation, [alpha]20(D) = + 34.0 degree, loss on drying, 6.93%; infrared spectrum, the same as that of the Lanatoside C Reference Standard (Control 784); thin-layer chromatography, two impurities detected; high-performance liquid chromatography, several impurities detected and the total amount estimated to be about 1.26%; assay by spectrophotometry, 103.0%. Based on the above results, the candidate material was authorized as the Lanatoside C Reference Standard (Control 981) of the National Institute of Health Sciences.

Government Agencies↗

PubMed1999

[Glycyrrhizic Acid Reference Standard (Control 991) of National Institute of Health Sciences].

The raw material of glycyrrhizic acid examined for preparation of the "Glycyrrhizic Acid Reference Standard". The analytical data obtained were: UV spectrum: Lambda max, 251 nm; specific absorbance (E (1%) 1cm) in ethanol at 251 nm, 146; IR spectrum, specific absorptions at 1716,1656, 1215, and 1170 cm-1; and the spectrum of raw material was consistent with that of Standard (Control 941). Also, thin-layer chromatography, no impurities detected; high-performance liquid chromatography, three impurities detected. The amount of each impurity was estimated at less than 0.1%, and the total amount of impurities was less than 0.2%. Based on the above results, the candidate material was authorized as the Glycyrrhizic Acid Reference Standard (Control 991) of the National Institute of Health Sciences.

Glycyrrhizic Acid↗

PubMed1999

[Tocopherol Succinate Reference Standard (Control 981) of National Institute of Health Sciences].

The raw material of tocopherol succinate was tested for preparation of the "Tocopherol Succinate Reference Standard (Control 981)". The analytical data obtained were: infrared spectrum same as that of the Tocopherol Succinate Reference Standard (Control 8510); specific absorbance, E(1%)1 cm (286 nm) = 40.7; thin-layer chromatography, no impurities detected until 50.0 microgram; high-performance liquid chromatography (HPLC),three impurities detected and amount of tocopherol succinate estimated to be 98.2%, loss on drying, 0.19%, assay by HPLC, 101.7%. Based on the above results, the raw material was authorized as the Japanese Pharmacopoeia Reference Standard (Control 981).

Government Agencies↗

PubMed1999

[Fluocinolone Acetonide Reference Standard (Control 981) of National Institute of Health Sciences].

The raw material of fluocinolone acetonide was examined for preparation of the "Fluocinolone Acetonide Reference Standard (Control 981)". The analytical data obtained were: melting point, 271.5 degree C; UV spectrum, Lambda max of 237.0 nm and specific absorbance in ethanol at 237 nm of 359.3; IR spectrum, same as that of the Fluocinolone Acetonide Reference Standard (Control 904); optical rotation, [alpha]20(D) = + 102.8; thin-layer chromatography, no impurities detected; high-performance liquid chromatography, one impurity detected and total amount estimated to be about 0.17%; loss on drying, 0.29%; assay by HPLC, 100.9%. Based on the above results, the raw material was authorized as the Fluocinolone Acetonide Reference Standard (Control 981) of the National Institute of Health Sciences.

Fluocinolone Acetonide↗

PubMed1999

[Fluocinonide Reference Standard (Control 981) of National Institute of Health Sciences].

The raw material of fluocinonide was examined for preparation of the "Fluocinonide Reference Standard (Control 981)". The analytical data obtained were: UV spectrum, lambda max of 237.4 nm; IR spectrum, same as that of the Fluocinonide Reference Standard (Control 841); optical rotation, [alpha]20(D) = + 84.4 degree, thin-layer chromatography, one impurity detected; high-performance liquid chromatography, three impurities detected and total amount estimated to be about 0.20%; loss on drying, 0.15%; assay by HPLC, 99.6% Based on the above results, the raw material was authorized as the Fluocinonide Reference Standard (Control 981) of the National Institute of Health Sciences.

Fluocinonide↗

PubMed1998

Regulation of insulin-stimulated GLUT4 translocation by Munc18c in 3T3L1 adipocytes.

Insulin stimulates glucose transporter (GLUT) 4 vesicle translocation from intracellular storage sites to the plasma membrane in 3T3L1 adipocytes through a VAMP2- and syntaxin 4-dependent mechanism. We have observed that Munc18c, a mammalian homolog of the yeast syntaxin-binding protein n-Sec1p, competed for the binding of VAMP2 to syntaxin 4. Consistent with an inhibitory function for Munc18c, expression of Munc18c, but not the related Munc18b isoform, prevented the insulin stimulation of GLUT4 and IRAP/vp165 translocation to the plasma membrane without any significant effect on GLUT1 trafficking. As expected, overexpressed Munc18c was found to co-immunoprecipitate with syntaxin 4 in the basal state. However, these complexes were found to dissociate upon insulin stimulation. Furthermore, endogenous Munc18c was predominantly localized to the plasma membrane and its distribution was not altered by insulin stimulation. Although expression of enhanced green fluorescent protein-Munc18c primarily resulted in a dispersed cytosolic distribution, co-expression with syntaxin 4 resulted in increased localization to the plasma membrane. Together, these data suggest that Munc18c inhibits the docking/fusion of GLUT4-containing vesicles by blocking the binding of VAMP2 to syntaxin 4. Insulin relieves this inhibition by inducing the dissociation of Munc18c from syntaxin 4 and by sequestering Munc18c to an alternative plasma membrane binding site.

3T3 Cells↗

PubMed1998

Left ventricular regional systolic motion in patients with right ventricular pressure overload.

Left ventricular regional systolic motion was investigated in patients with right ventricular pressure overload and 10 controls using tagged cine magnetic resonance imaging. The regional shortening fraction was determined in four segments (septal, lateral, inferior, and anterior) on the short-axis image. An asynchrony index, nonhomogeneity of regional shortening, was calculated. Septal shortening in these patients was depressed, and showed an inverse correlation with the right-to-left ventricular peak pressure ratio (r=-0.80, P<0.01). Lateral shortening was greater in the patients than in the controls (P<0.01). The asynchrony index was significantly greater in the patients than in the controls (P<0.01), and correlated with the right-to-left systolic pressure ratio (r=0.64, P=0.02) and the left ventricular end-diastolic pressure (r=0.79, P<0.01). The altered distribution of regional circumferential shortening results in an increased heterogeneity of regional systolic motion. These findings may have important implications for the assessment of ventricular function in patients with right ventricular pressure overload.

Adult↗

PubMed1998

The phosphatidylinositol 3-kinase inhibitor wortmannin sensitizes quiescent but not proliferating MG-63 human osteosarcoma cells to radiation.

Recent genetic and biochemical studies indicate that DNA-dependent protein kinase (DNA-PK) plays an important role in DNA double-strand break (dsb) repair and V(D)J recombination. Since the catalytic subunit of DNA-PK (DNA-PKcs) has high sequence homology with phosphatidylinositol 3-kinase (PI 3-kinase), we examined the effect of wortmannin, a specific inhibitor of PI 3-kinase, on the survival of human tumor cells after X-irradiation. The present study demonstrates that wortmannin at 20 microM is an effective radiosensitizer of quiescent (Q), but not proliferating (P) cells. In addition, the rejoining of DNA dsb is significantly inhibited in Q, but not in P cells. Finally, we found that Q cell extracts have approximately five-fold less DNA-PK activity than those of P cells. After a 2 h exposure to wortmannin, the DNA-PK activity of Q cell extracts was considerably lower than that of P cells. This can explain why wortmannin sensitizes Q, but not P cells to radiation.

Androstadienes↗

PubMed1998

In vivo stimulation-induced release of manganese in rat amygdala.

The role of manganese ions in neural functions is poorly understood because of the low level of manganese in the brain. An excess of this ion is associated with neurological disorders such as extrapyramidal symptoms. We demonstrated that manganese may be taken up by piriform neurons (tertiary olfactory neurons) after release from the terminals of secondary olfactory neurons, in which 54Mn taken up by the soma may be anterogradely transported [A. Takeda, Y. Kodama, S. Ishiwatari, S. Okada, Manganese transport in the neural circuit of Rat CNS, Brain Res. Bull. (45) (1998) 149-152]. Here we demonstrate for the first time that 54Mn previously taken up into the amygdala is released with neurotransmitters into the extracellular space during stimulation with high K+. The results suggest that the role of manganese ions in the amygdala, and probably in the olfactory system, is dynamically linked to neural signalling processes.

Amygdala↗

PubMed1998

c-Fos induces apoptosis in germinal center B cells.

We examined the role of c-Fos in the differentiation of mature B cells into IgG-producing cells using transgenic mice carrying the c-fos gene under the control of the IFN-alpha/beta-inducible Mx promoter (Mx-c-fos) or the constitutive H-2Kb promoter (H2-c-fos). Splenic B cells from Mx-c-fos mice were cultured with LPS and rIL-4, and IgG1+ B cells were developed in the culture after day 3. When IFN-alpha/beta was added to the culture from day 2, development of IgG1+ B cells was perturbed, and the number of apoptotic cells increased within 24 h, suggesting that c-Fos induces apoptosis in Ig class-switching B cells. To confirm the effect of c-Fos on B cell differentiation in vivo, H2-c-fos mice were immunized with DNP-OVA. The mice produced primary IgM, but not IgG, anti-DNP Ab in serum and failed to generate germinal centers in spleen. The perturbation of germinal center formation in H2-c-fos mice was rescued by mating them with transgenic mice carrying the bcl-2 gene with the Ig promoter. However, primary IgG1 anti-DNP Ab production was still suppressed in doubly transgenic mice, suggesting that Bcl-2 can delay the time of c-Fos-induced apoptosis in Ig class-switching B cells but cannot rescue the death. Since c-Fos is induced in mature B cells reacted with Ags, and clonal deletion of self-reactive B cells in germinal centers is insensitive to Bcl-2, these results suggest that c-Fos plays a causal role in clonal deletion of germinal center B cells.

Animals↗

PubMed1998

24R,25-dihydroxyvitamin D3 increases cyclic GMP contents, leading to an enhancement of osteocalcin synthesis by 1,25-dihydroxyvitamin D3 in cultured human osteoblastic cells.

The effect of the physiological vitamin D metabolite 24R, 25-dihydroxyvitamin D3 [24R,25(OH)2D3] on human osteoblastic cells was assessed. Physiological concentrations (10(-9)-10(-8) M) of 24R, 25(OH)2D3 significantly increased the cyclic guanosine 5'-monophosphate (cGMP) content in the human osteoblastic cells by approximately 200% in 5 to 15 min. In contrast, 24S, 25-dihydroxyvitamin D3 had only a weak effect on the cGMP content, and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] did not affect the content. The production of osteocalcin was not induced by 10(-9)-10(-8) M of 24R,25(OH)2D3 in the absence of 1,25(OH)2D3. However, the same concentration of 24R,25(OH)2D3 showed stimulatory effects on osteocalcin synthesis in the presence of 10(-9) M 1, 25(OH)2D3. Rp-8Br-cyclic GMP, a specific inhibitor of cyclic GMP-dependent protein kinase, significantly inhibited the cooperative effect of 24R,25(OH)2D3 with 1,25(OH)2D3 on the osteocalcin synthesis, although Rp-8Br-cyclic AMP, a specific inhibitor of cyclic AMP-dependent protein kinase, did not affect the cooperative effect. In addition, okadaic acid enhanced the osteocalcin synthesis induced by 1,25(OH)2D3. These observations suggest that 24R,25(OH)2D3 has a unique activity of increasing cGMP contents in osteoblastic cells, and that the increase in cGMP contents may lead to the cooperative effect of 24R,25(OH)2D3 with 1, 25(OH)2D3 on osteocalcin synthesis. These data support the hypothesis that 24R,25(OH)2D3 has a physiological role in human bone and mineral metabolism.

24,25-Dihydroxyvitamin D 3↗

PubMed1998

Zinc transport from the striatum and substantia nigra.

65Zn was unilaterally injected into the striatum or substantia nigra of rats to see the transport of intracerebral zinc (Zn). In the case of intrastriatal injection, 65Zn was densely distributed in the ipsilateral medial forebrain bundle (MFB) and the substantia nigra. On unilateral colchicine injection into the MFB, 65Zn distribution in the ipsilateral substantia nigra decreased significantly compared to that of the contralateral one after 65Zn injection into the bilateral striata. These results suggest the presence of axonal transport of 65Zn taken up by striatonigral gamma-aminobutyric acid (GABA)-ergic and/or nigrostriatal dopaminergic neurons. On the other hand, in the case of intranigral injection, 65Zn was distributed in the ipsilateral MFB, striatum, globus pallidus, pontine reticular nuclei, and pontine nuclei. 65Zn distribution in the pons 1 day after intranigral injection was very similar to that 6 days after intrastriatal injection, suggesting that, in the case of intrastriatal injection of 65Zn, nigral 65Zn, which was transported anterogradely and/or retrogradely from the striatum, was transported to the postsynaptic neurons through the synapse and then transported to the pons.

Animals↗

PubMed1998

Regenerative response in acute renal failure due to vitamin E deficiency and glutathione depletion in rats.

In this study, we investigated some factors contributing to renal regeneration after acute renal failure (ARF) induced by vitamin E (VE) deficiency and glutathione (GSH) depletion. Acute renal failure was induced by feeding rats a vitamin E-deficient diet for 6 weeks and then injecting buthionine sulfoximine (BSO), a glutathione-depleting agent. The level of hepatocyte growth factor (HGF), a renotropic factor for regeneration in the kidney, showed a transient increase at 5 hr after the BSO treatment. Subsequently, renal ornithine decarboxylase (ODC) activity, a marker of G1 phase, and labeling index (LI) of proliferating cell nuclear antigen (PCNA), a marker of DNA synthesis (S phase), reached peaks at 10 and 53 hr after the injection, respectively. Thus, it appears that the increase in ornithine decarboxylase activity and subsequent elevation in proliferating cell nuclear antigen labeling index following the increase in the hepatocyte growth factor level in the kidneys are closely related to the renal regenerative response after acute renal failure.

Acute Kidney Injury↗

PubMed1998

Characterization of a novel human natural killer-cell line (NK-YS) established from natural killer cell lymphoma/leukemia associated with Epstein-Barr virus infection.

A novel cell line was established from a patient with a leukemic-state nasal angiocentric natural killer (NK) cell lymphoma with systemic skin infiltration. The morphology of the leukemic cells was large-granular-lymphocyte (LGL), and their immunophenotype was CD2+, CD3-, CD5+, CD7+, CD16-, CD56+, and CD57-. The presence of Epstein-Barr viral (EBV) genome was shown in specimens from the patient's nose, skin, and peripheral blood by in situ hybridization using an EBV-encoded small RNA-1 probe or by Southern blotting using a terminal-repeat probe of the EBV genome. Leukemic cells were cocultured with a mouse stromal cell line (SPY3-2) in the presence of 100 U/mL recombinant human interleukin-2 and a novel stromal cell-independent cell line, NK-YS, was established. The NK-YS cells showed LGL morphology and expressed surface CD2, CD5, CD7, CD25, CD56, and CD95. The NK-YS cells retained cytotoxicity against K562 and Jurkat cells. A Southern blotting using a terminal-repeat probe of EBV showed that NK-YS and fresh leukemic cells had a clonal EBV genome, whereas the T-cell receptor beta and gamma chain genes of NK-YS were not rearranged. In an immunocytochemical analysis, the NK-YS cells showed a type-II latent infection of EBV. The NK-YS cells preserved the original characteristics of NK cell lymphoma/leukemia and will be a useful tool for the study of biological characteristics of EBV-associated nasal angiocentric NK cell lymphoma/leukemia.

Adult↗

PubMed1998

Kinetic Analyses of Colloidal Crystallization in Alcoholic Organic Solvents and Their Aqueous Mixtures As Studied by Reflection Spectroscopy.

Reflection spectroscopy is used for the kinetic analyses of the nucleation and growth process of colloidal crystals of silica spheres (110 nm in diameter) in exhaustively deionized suspensions of purely alcoholic organic solvents (methyl alcohol, ethyl alcohol, and ethylene glycol) and aqueous mixtures with alcohols (methyl, ethyl, n-propyl, and n-butyl alcohols and ethylene glycol). Sphere concentrations studied range from 0.001 to 0.01 in volume fraction, rather high compared with those in water. Induction periods are from 5 to 2000 s and are prolonged with decreasing sphere concentration. Nucleation rates are 10(-3) to 10(3) mm-3 s-1 and increase sharply as sphere concentration increases. The crystal growth rates, v have been determined from the increase of intensity in the sharpened reflection peaks. Values of v range from 1 to 27 µm/s and decrease linearly as the reciprocal sphere concentration increases. Nucleation and crystallization rates decrease sharply as the fraction of the organic solvents increases in the mixtures with water. The importance of the electrostatic intersphere repulsion through the electrical double layers and the cooperative and synchronized fluctuation of colloidal spheres in the crystallization processes is supported. Copyright 1998 Academic Press.

Journal Article↗

PubMed1998

Regional ventricular systolic abnormalities caused by a rudimentary chamber in patients with univentricular hearts.

Previous studies have demonstrated that regional wall motion abnormalities are common in univentricular hearts; however, the mechanism of this abnormality and its relation to hemodynamics remain unclear. The aim of this study was to document and analyze the etiology of regional wall motion abnormality and its relation to hemodynamics in univentricular hearts. Sixteen patients (age 11+/-6 years) were examined. A tagged cine magnetic resonance imaging method that superimposes "tags" on myocardium was used to assess regional systolic motion. The tags were traced from end-diastole to end-systole, and the percent regional shortening fraction was calculated as the shortening ratio. The tags were positioned on 6 segments. Normal ranges for wall motion were established from 10 normal volunteers. An asynchrony index was calculated as the SD divided by the mean regional shortening fraction to quantify asynchronous regional motion. Hemodynamic parameters were also obtained by cardiac catheterization. In patients, regional shortening fraction was significantly lower in segments adjacent to the rudimentary chamber compared with normal values in both circumferential and longitudinal directions (p <0.05 and p <0.01, respectively). The asynchrony index was much greater in patients than in controls (62+/-25 vs 27+/-10, p <0.01). The index correlated with rudimentary chamber volume and the rudimentary/main chamber volume ratio (r = 0.58, r = 0.79, respectively). Furthermore, the index correlated with end-diastolic pressure (r = 0.82). The rudimentary chamber may play an important role in causing asynchronous regional motion, and this motion may contribute to ventricular diastolic dysfunction.

Adolescent↗

PubMed1998

Cyclic glucans produced by the intramolecular transglycosylation activity of potato D-enzyme on amylopectin.

Potato D-enzyme catalyses an intramolecular transglycosylation reaction on amylose to produce cycloamylose, a novel cyclic alpha-1, 4 glucan. To determine if a similar activity could be observed with a high molecular weight branched substrate, recombinant potato D-enzyme was incubated with amylopectin. The substrate was converted into two fractions of lower molecular mass. Fraction I comprised 15% cyclic molecules of which the majority contained both alpha-1,4 and alpha-1,6 links. These were shown to be branched molecules with branches shorter than those in amylopectin. Fraction II comprised 80% cyclic molecules of which the majority contained only alpha-1,4 links (cycloamylose). Since fraction II appeared before fraction I, we propose that D-enzyme first catalysed the cyclisation of the outer side chains of amylopectin and then the cyclisation of inner chains to produce branched clusters. These results demonstrate that D-enzyme can catalyse the transfer of branched glucans, and suggest novel ways in which it may participate in starch metabolism in plants.

Amylopectin↗