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Biomedical subjects

T Nikaido

Publications and source records attributed to T Nikaido.

At least 145 records · Page 8Linked to original sources
PubMed1994

Early tensile bond strengths of several enamel and dentin bonding systems.

Tensile bond strength tests are commonly used for the evaluation of adhesive dental materials. The majority of these tests are carried out after 24 h of storage in water. However, determination of the early tensile bond strength could be more important, especially in relation to gap formation between the cavity surface and the restorative material. This study investigated the tensile bond strengths of five enamel/dentin bonding systems and two experimental dentin bonding systems. Tensile bond strengths were obtained at one min, ten min, and 24 h after the resin composite was cured. Bond strengths at the early stages were always somewhat less than the 24-hour test results. For the enamel/dentin bonding systems, a significant difference was found between the enamel and dentin bond strengths at all time periods, except with Superbond D-liner and Liner Bond. The experimental group with glyceryl methacrylate as the primer produced a good 24-hour result (14.3 MPa), but the early bond strengths were no different from those in the non-primer-treated groups. It was concluded that this material may actually retard the polymerization of the bonding resin. Previous workers have suggested that a tensile bond strength in the order of 20 MPa is necessary for gap-free restorations to be obtained. Should this be the case, then all of the materials tested, from the aspect of early bond strength, lack the strength for prevention of gap formation, although Superbond D-liner and Liner Bond approached this hypothetical figure. These systems, Superbond D-liner and Liner Bond, also exhibit small differences between the enamel and dentin tensile bond strengths.

Analysis of Variance↗
PubMed1994

Three new furostanol saponins from the bulbs of Ipheion uniflorum.

Phytochemical screening of the bulbs of Ipheion uniflorum (Liliaceae) has led to the isolation of three new furostanol saponins (2-4) along with a known phytoecdysteroid, ecdysterone (1). The structures of the new compounds were determined by two-dimensional NMR techniques, 1H-1H correlation spectroscopy (COSY), homonuclear Hartmann-Hahn (HOHAHA), phase-sensitive nuclear Overhauser effect spectroscopy (NOESY), heteronuclear multiple quantum coherence (HMQC) and heteronuclear multiple-bond correlation (HMBC) spectra, and hydrolysis to be 3 beta-hydroxy-22 alpha-methoxy-26-O-beta-D- glucopyranosyloxy-5 alpha-furost-25(27)-en-2-one 3-O-[O-alpha-L-rhamnopyranosyl-(1-->2)-O-[O-alpha-L-arabinopyranosyl+ ++- (1-->2)-O-[beta-D-xylopyranosyl-(1-->3)]-beta-D-glucopyranosyl-(1-->4)]- beta-D-galactopyranoside) (2) and its 25(27)-dihydro derivatives (3: 25S; 4: 25R). The inhibitory activity exhibited by compounds 1-4 and the corresponding spirostanol saponins (2a and 3a) of 2 and 3 on cAMP phosphodiesterase was assayed as a primary screening test to identify new compounds with medicinal potential.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1994

Triterpenoid saponins from Ardisia crenata and their inhibitory activity on cAMP phosphodiesterase.

Two novel triterpenoid saponins, ardisicrenoside C (1) [3 beta-O-(alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->4)- [beta-D-glucopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl)-16 alpha, 28-dihydroxy-olean-12-en-30-oic acid 30-O-beta-D-glucopyranosyl ester] and ardisicrenoside D (2) [3 beta-O-(beta-D-xylopyranosyl-(1-->2)- beta-D-glucopyranosyl-(1-->4)-[beta-D-glucopyranosyl-(1-->2)]-alpha-L- arabinopyranosyl)-16 alpha, 28-dihydroxy-olean-12-en-30-oic acid 30-O-beta-D-glucopyranosyl ester] were isolated from the roots of Ardisia crenata. Structure assignments are based on spectroscopic data including 2D-NMR (correlation spectroscopy (COSY), homonuclear Hartmann-Hahn spectroscopy (HOHAHA), heteronuclear correlated spectroscopy (HETCOR), heteronuclear multiple bond correlation (HMBC) and rotating frame NOE spectroscopy (ROESY)) experiments and some chemical reactions. In addition, the isolated saponins along with their prosapogenins and sapogenins have been evaluated for their inhibitory activity on cAMP phosphodiesterase as a primary screening test for new medicinal compounds.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1994

New steroidal saponins from the bulbs of Allium giganteum exhibiting potent inhibition of cAMP phosphodiesterase activity.

A new spirostanol saponin and two new furostanol saponins were isolated from the fresh bulbs of Allium giganteum together with several known saponins. The structures of the new compounds were determined on the basis of spectroscopic data, the products formed on hydrolysis and by comparing their properties with those of known compounds. The isolated saponins and their derivatives were evaluated for inhibitory activity by examining their action on cAMP phosphodiesterase as a primary screening test to identify new medicinal agents.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1994

Steroidal constituents from the underground parts of Reineckea carnea and their inhibitory activity on cAMP phosphodiesterase.

Phytochemical analysis of the underground parts of Reineckea carnea resulted in the finding of twelve steroidal constituents, five of which appeared to be new compounds and one to be the first isolation from a natural source. The identification and structural determination of the steroidal compounds were established by spectroscopic analysis and hydrolysis. The isolated saponins were evaluated for inhibitory activity on cAMP phosphodiesterase as a primary screening test to find new medicinal materials.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1993

Soft tissue vascular tumors. A flow cytometric DNA analysis.

BACKGROUND: The clinical behavior of soft tissue vascular tumors is difficult to predict on histologic grounds alone. METHODS: To assess the usefulness of DNA flow cytometry in predicting the biologic behavior of these tumors, the authors studied 51 soft tissue vascular tumors by DNA flow cytometry of paraffin-embedded tissue. RESULTS: All 20 capillary hemangiomas, one epithelioid hemangioma, two spindle cell hemangioendotheliomas, and two benign hemangiopericytomas had a diploid DNA content. Of the 20 patients with angiosarcomas, their ages ranged from 9-80 years (mean, 44.0 years), and the mean follow-up period was 16.5 months. Ten tumors (including two postmastectomy angiosarcomas) were cutaneous, six were deep soft tissues, and four were from other sites. These tumors were classified histologically into three types: sinusoidal (n = 10), capillary (n = 7), and mixed type (n = 3). Thirteen of the angiosarcomas (65%) were diploid, and seven (35%) were aneuploid. Three patients with angiosarcoma had lung metastases at initial diagnosis, and seven had them later in the course. Nine patients died of their disease within a period of 18 months after the initial diagnosis. All five patients with malignant hemangiopericytoma died of their disease. Three of these lesions had a diploid DNA content, and two had an aneuploid content. Although it was found that all benign and intermediate-grade malignant tumors were diploid, there were no significant correlations among histologic type, DNA ploidy, and clinical outcome in angiosarcomas and malignant hemangiopericytomas. CONCLUSIONS: Based on this study, DNA analysis has limited value in predicting the biologic behavior of malignant vascular tumors of the soft tissue.

Adolescent↗
PubMed1993

Lanosterol and 27-norlanosterol oligosaccharides from the bulbs of Chionodoxa gigantea.

New lanosterol and 27-norlanosterol oligosaccharides were found in the bulbs of Chionodoxa gigantea. Their structures were established mainly by extensive 2D NMR analysis as well as by comparison with spectral data of known compounds. The inhibition of cyclic AMP phosphodiesterase by the lanosterol derivatives was assayed as the primary screening test to find new medicinal materials.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1993

Steroidal saponins from the bulbs of Lilium regale and L. henryi.

Two new and three known steroidal saponins were isolated from the fresh bulbs of Lilium regale and two known saponins from those of L. henryi. The structures of the new saponins were established by extensive spectral data, hydrolysis and chemical correlation as (25R)-27-O-[(S)-3-hydroxy-3-methylglutaroyl]-spirost-5 -ene-3 beta,27-diol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-O-[beta-D-glucopyranosyl-(1-->3)]- beta-D-glucopyranoside and (25S)-spirost-5-ene-3 beta,17 alpha,27-triol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-O-[beta-D-glucopyranosyl-(1-->2)-O- beta-D-glucopyranosyl-(1-->4)]-beta-D-glucopyranoside. Inhibitory activity of the saponins on cyclic AMP phosphodiesterase was evaluated.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1993

Agapanthussaponins A-D, new potent cAMP phosphodiesterase inhibitors from the underground parts of Agapanthus inapertus.

The saponin fraction prepared from the methanolic extract of the underground parts of Agapanthus inapertus was found to exhibit inhibitory activity on cAMP phosphodiesterase (55.2%) at a concentration of 100 micrograms/ml. From this fraction, four new steroidal saponins, designated as agapanthussaponin A (1), B (2), C (3) and D (4), were isolated as the active principles, along with an inactive new furostanol saponin (5). The structures of 1-5 were determined by spectroscopic data and hydrolysis. The IC50 of 1-4 on cAMP phosphodiesterase were 0.7, 1.2, 1.1 and 2.0 (x 10(-5) M), respectively, which are more potent than that of papaverine (IC50 3.0 x 10(-5) M).

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1993

Tensile bond strength and curing gap formation of a dentin bonding resin.

Tensile bond strength and contraction gap tests were carried out using a new dentin bonding resin in association with various dentin conditioning and priming materials in vitro. For the tensile bond test, significant differences were found between the nonconditioned and conditioned dentin, and the primed and non-primed dentin surfaces. The strongest bond was obtained using a combination of phosphoric acid conditioning and priming with HEMA in glutaraldehyde at 151.3 kgf/cm2. Gap test results showed the presence of gaps in all of the test groups, but with variation in the extent of gap formation. A not significant, inverse correlation was determined between the tensile bond strength and gap tests (R = -0.65). The new bonding resin obtained good bond strengths in all cases, but high bond strengths can only be obtained with a combination of etching and priming. Similarly, the smallest gaps were associated with the etched and primed groups.

Animals↗
PubMed1992

Quercetin arrests human leukemic T-cells in late G1 phase of the cell cycle.

The effect of quercetin, a flavonoid found in many plants, on the proliferation of human leukemic T-cells was analyzed. Quercetin reversibly blocked the cell cycle at a point 3-6 h before the start of DNA synthesis. Expression of the growth-related genes histone H4, cyclin A and B, and p34cdc2 was suppressed in cells blocked with quercetin. Comparison of the quercetin arrest points with those of the cell cycle inhibitors aphidicolin and mimosine revealed a temporal order of arrest points in G1 of quercetin, mimosine, and aphidicolin. Mimosine and aphidicolin did not inhibit the expression of cyclin A or p34cdc2, whereas all three reagents inhibited expression of cyclin B. Low concentrations of the protein inhibitor cycloheximide inhibited release of the quercetin but not the mimosine or aphidicolin block. A [35S]methionine-labeled M(r) 60,000 protein disappeared in quercetin-treated cells and was rapidly synthesized after removal of quercetin, suggesting the possibility that the M(r) 60,000 protein induces DNA synthesis after the cell is released from a quercetin block. These results suggest the usefulness of quercetin in studies of the regulation of late G1 phase.

Aphidicolin↗
PubMed1992

A flow cytometric DNA analysis of giant cell tumors of bone including two cases with malignant transformation.

BACKGROUND AND METHODS: Flow cytometric DNA analysis was performed on 30 cases of giant cell tumor (GCT) of bone with the use of paraffin-embedded sections. RESULTS: According to the criteria of Huvos, they were classified histologically into three groups: Grade 1, 26 cases; Grade 2, 4 cases; and Grade 3, no cases. Among the Grade 1 cases, 21 were diploid and 5 were aneuploid. Of the four Grade 2 cases, three were diploid and one was aneuploid. Nine patients had local relapses. Among four patients with complications by lung metastases, two have remained well at 18 and 157 months with the metastases. The other two patients, who had Grade 1 DNA diploid GCT of the 11th thoracic spine, had malignant transformation (osteosarcoma) resulting from radiation therapy. In one patient, the primary lesion exposed to radiation and the lung lesions were diploid, but in the other patient both were found to be aneuploid at autopsy. No significant differences of S-phase fraction were observed between two different grade groups. There was no significant correlation among DNA ploidy, histologic grade, and the presence or absence of lung metastases. CONCLUSIONS: Based on this study, the DNA analysis has a limitation in predicting the biologic behavior of GCT.

Adolescent↗
PubMed1992

Steroidal saponins from Smilax riparia and S. china.

Two new neotigogenin glycosides were isolated from the rhizomes and roots of Smilax riparia and a new isonarthogenin glycoside from those of S. china. The structures were elucidated by a combination of spectroscopic analysis and hydrolysis followed by spectral and chromatographic analysis. Several known saponins were also isolated and identified. The inhibitory activity of the saponins on cAMP phosphodiesterase was examined.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1992

Steroidal saponins from the rhizomes of Smilax sieboldii.

Six new steroidal saponins were isolated from the rhizomes of Smilax sieboldii. Their structures were determined by spectroscopic analysis and hydrolysis to be 3 beta-hydroxy-(25R)-5 alpha-spirostan-6-one (laxogenin) 3-O-beta-D-glucopyranosyl-(1----4)-O-[alpha-L-arabinopyranosyl-(1- ---6)]-beta-D-glucopyranoside, laxogenin 3-O-alpha-L-arabinopyranosyl-(1----6)-beta-D-glucopyranoside, 3 beta,27-dihydroxy-(25S)-5 alpha-spirostan-6-one 3-O-beta-D-glucopyranosyl-(1----4)-O-[alpha-L-arabinopyranosyl-(1- ---6)]- beta-D-glucopyranoside, 26-O-beta-D-glucopyranosyl-3 beta,22 xi,26-trihydroxy-(25R)-5 alpha-furostan-6-one 3-O-alpha-L-arabinopyranosyl-(1----6)-beta-D-glucopyranoside, 26-O-beta-D-glucopyranosyl-3 beta,22 xi,26-trihydroxy-(25R)-5 alpha-furostan-6- one 3-O-beta-D-glucopyranosyl-(1----4)-O-[alpha-L-arabinopyranosyl-(1- ---6)]- beta-D-glucopyranoside and (25R)-5 alpha-spirostan-3 beta-ol (tigogenin) 3-O-beta-D-glucopyranosyl-(1----4)-O-[alpha-L-arabinopyranosyl- (1----6)]-beta-D-glucopyranoside. The inhibition of cAMP phosphodiesterase by the saponins was evaluated.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1992

Jatropham derivatives and steroidal saponins from the bulbs of Lilium hansonii.

Two new jatropham derivatives and three new steroidal saponins were isolated from the fresh bulbs of Lilium hansonii, along with previously known compounds. The structures of the new compounds were elucidated, on the basis of spectroscopic data and chemical evidence, and by comparing them with those of known compounds, as (-)-5-hydroxy-3-methyl-3-pyrrolin-2-one (jatropham) 5-O-beta-D-glucopyranosyl-(1----3)-beta-D-glucopyranoside, (2S*,4R*)-1-(3-methyl-2-oxo-3-pyrrolinyl)-4-methyl-5-oxo-2-pyrr olidinecarboxyli c acid, 26-O-beta-D-glucopyranosyl-(25R)-5 alpha-furostan-3 beta,22 zeta-diol 3-O-alpha-L-rhamnopyranosyl-(1----2)-O-[beta-D-glucopyranosyl-(1----4)]- beta-D-glucopyranoside, (25R)-5 alpha-spirostan-3 beta,12 alpha-diol 3-O-alpha-L-rhamnopyranosyl-(1----2)-O-[beta-D-glucopyranosyl-(1----4)]- beta-D-glucopyranoside and (25R)-spirost-5-en-3 beta,12 alpha-diol 3-O-alpha-L-rhamnopyranosyl-(1----2)-O-[beta-D-glucopyranosyl-(1----4)]- beta-D-glucopyranoside, respectively. The stereostructure of jatropham dimer, the plain structure of which was presented previously, was confirmed by X-ray crystallographic analysis. The inhibitory activity on cyclic AMP phosphodiesterase of the steroidal saponins was evaluated.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1992

[The study of Chinese herbal medicinal prescription with enzyme inhibitory activity. VI. The study of makyo-kanseki-to with adenosine 3',5'-cyclic monophosphate phosphodiesterase].

A Chinese herbal medicinal prescription, Makyo-kanseki-to, was studied for the inhibitory activity of adenosine 3',5'-cyclic monophosphate (cAMP) phosphodiesterase. The effect for the inhibitory activity of cAMP phosphodiesterase by combination with constituent crude drugs of the prescription was studied. Gypsum acted as a mitigatory component for Ephedra herb and Glycyrrhiza in cAMP phosphodiesterase inhibition test.

3',5'-Cyclic-AMP Phosphodiesterases↗