Search PubMed⌕ Search

Biomedical subjects

T Takeuchi

Publications and source records attributed to T Takeuchi.

At least 1,333 records · Page 74Linked to original sources
PubMed1989

A study on spin-labelled oligonucleotide synthesis and its electron spin resonance behavior in solution.

An oligonucleotide spin-labelled with 4-amino-2,2,6,6-tetramethylpiperidine-N-oxyl (4-amino-TEMPO) at the internucleotide bond (d-Tp(L)TpTpTpT) prepared by oxidation of the pentanucleotide containing the H-phosphonate diester (d-Tp(H)TpTpTpT) in the presence of 4-amino-TEMPO, was separated and identified by high-performance, reverse-phase liquid chromatography combined with detection by electron spin resonance spectroscopy. This spin-labelled oligonucleotide produced a triplet with the slightly broadened M1 = -1 ESR component, while a triplet with almost equal intensities was obtained from the spin-label. The M1 = -1 component from the labelled oligonucleotide was further broadened in the presence of poly(A) which forms a complementary double strand with this molecule.

Chromatography, Liquid↗
PubMed1989

An artifact in the ESR spectrum obtained by spin trapping with DMPO.

In order to overcome a common problem in spin trapping with high concentrations of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) where ESR spectra are obtained which include an unidentified set of lines composed of a triplet of doublets, commercial DMPO was analyzed for its impurities by high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy. It has been determined that this undesirable ESR spectrum is due to an impurity included in the spin trap. This compound has been assigned to the hydroxylamine which is a DMPO-derivative having an epoxy ring located at the 2 and 3 positions.

Animals↗
PubMed1989

Changes in the concentrations of vitamin D and its metabolites in the plasma of healthy subjects orally given physiological doses of vitamin D2 by multivitamin or vitamin D preparations.

Changes in the concentrations of vitamin D and its metabolites in plasma of healthy subjects orally given physiological doses of vitamin D2 by multivitamin or vitamin D liquid preparations were determined and the bioavailability of vitamin D was studied. Separative assay on the D2 and D3 compounds of vitamin D, 25-hydroxyvitamin D (25-OH-D), 24R,25-dihydroxyvitamin D [24,25(OH)2D], and 1 alpha,25-dihydroxyvitamin D [1,25(OH)2D] was performed in plasma of eight healthy male volunteers. When the concentrations of vitamin D and its metabolites in plasma of volunteers were assayed after daily oral administration of 400 IU of vitamin D2 in a form of multivitamin tablet for 1 week, the variations of vitamin D3 and its metabolites in plasma levels were very small. In contrast, the concentrations of 25-OH-D2 and 1,25(OH)2D2 slightly increased after the administration, while neither vitamin D2 nor 24,25(OH)2D2 was detected. A single dose of 4,000 IU of vitamin D2 was orally given to the volunteers in a form of a vitamin D liquid preparation and the hourly variations were observed during 24 h. These concentrations of vitamin D2, 25-OH-D2, and 1,25(OH)2D2 were slightly higher than those of the repeated doses. The result suggests that even the high dose of 4,000 IU has little effect on the plasma levels of vitamin D2 and its metabolites by a single dose, indicating a low risk for hypervitaminosis D.

Administration, Oral↗
PubMed1989

[Treatment of suture-thread stones in the kidney by percutaneous nephrolithotripsy. Report of a case].

Percutaneous nephrolithotripsy was performed successfully to the stones in the left kidney, in which pyelolithotomy had been done three years earlier. There were foreign body stones with silk sutures used in the previous surgery as the nuclei. All the stones were removed, and a stricture in the renal pelvis was liberated endoscopically. No reports of endoscopic management to foreign body stones in a kidney are found in the Japanese literature. A few ways of the treatment are discussed.

Adult↗
PubMed1989

[Acute focal bacterial nephritis (acute lobar nephronia) report of two cases].

Acute focal bacterial nephritis (AFBN) is one of the acute renal infections, its entity can be distinguished from other renal infections by the findings of sonography and computed tomography. There is no evidence of liquefaction in focal masses of AFBN in contrast to renal abscess. We present two cases with AFBN. The first case was a 52-year-old man with diabetes mellitus and benign prostatic hypertrophy. The second case was a 24-year-old woman with bilateral vesico-ureteral refluxes. Although their initial symptoms mimicked those of acute pyelonephritis, the findings of sonography and computed tomography revealed renal masses. They were treated with anti-microbial agents, and showed rapid improvement on both clinical symptoms and renal masses.

Acute Disease↗
PubMed1989

N-salicylidene derivatives of pirarubicin.

The preparation and biological evaluation of N-salicylidene derivatives of pirarubicin are described. Pirarubicin was treated with various kinds of aryl aldehydes. Most of compounds synthesized here were more active than pirarubicin in vitro. Some of them showed significant prolongation of the survival period in experimental mice by oral administration. Interestingly, a derivative containing forphenicine exhibited the broadest dose-response range by intraperitoneal administration.

Animals↗
PubMed1989

Biosynthesis of benanomicins.

The biosynthesis of benanomicins A and B, produced by actinomycete strain MH193-16F4, was investigated by feeding experiments with 14C- and 13C-labeled compounds followed by measurement of radioactivity and 13C NMR analysis. A 2D double quantum coherence NMR spectrum of benanomicin A derived from sodium [1,2-13C2]acetate provided the location of intact acetate units, and confirmed the 13C assignments of benanomicins. The results indicate that the aglycone of benanomicins is derived from a dodecaketide, methionine and alanine.

Actinomycetales↗
PubMed1989

Serum effect on cellular uptake of spermidine, spergualin, 15-deoxyspergualin, and their metabolites by L5178Y cells.

Spergualin (SG) and 15-deoxyspergualin (DSG) were more slowly incorporated into L5178Y cells than spermidine. SG and DSG inhibited carrier-mediated transport of [3H]spermidine competitively with inhibition constants of 0.67 mM and 0.45 mM, respectively. Addition of calf serum stimulated uptake of [3H]spermidine into the cells in a serum concentration-dependent manner. The effect was not observed when horse serum was used in place of calf serum. Preincubation of spermidine in calf serum for 1 hour before addition to cells remarkably decreased cellular incorporation of tritium. Three amine oxidase inhibitors, aminoguanidine, 3-hydroxybenzyloxyamine, and semicarbazide, inhibited stimulation of uptake of [3H]spermidine by calf serum and the decrease of it by preincubation in calf serum. So we propose that cellular incorporation or binding of products generated by oxidation of spermidine by amine oxidase in calf serum was much faster than that of spermidine itself and they were unstable and transformed quickly to unincorporable or non-binding substances if cellular targets were not present. Effect of amine oxidase inhibitors on cytotoxic activity of SG and DSG were determined in low and high concentrations of calf serum. In the presence of 10% calf serum in the basal medium, cytotoxicity to L5178Y cells by SG and DSG was suppressed at high drug concentrations (above 10 micrograms/ml) and enhanced at low drug concentrations (below 2.5 micrograms/ml) by amine oxidase inhibitors. In the presence of 0.5% calf serum suppression of cytotoxicity at high drug concentrations by amine oxidase inhibitors was also observed, but enhancement at low drug concentrations was obscure. These data may suggest the existence of two kinds of cytotoxic mechanism of SG and DSG, one dependent on and one independent of amine oxidase in serum.

Amine Oxidase (Copper-Containing)↗
PubMed1989

Tumor cell permeability to peplomycin.

The uptake of [3H]peplomycin-Cu(II) ([3H]PEP-Cu(II)) into various tumor cell lines was studied. The time course of [3H]PEP-Cu(II) uptake into AH66, AH66F, Ehrlich and P388 cells was biphasic. The first phase of uptake was completed within 5 minutes. The second, slower phase, of uptake into AH66, AH66F and Ehrlich cells increased linearly with incubation time, but that into P388 cells reached a plateau level. In L1210 cells, only the first rapid uptake was observed. The lower uptake into P388 and L1210 cells during the second phase may be related to their insensitivity to PEP. However, the uptake into AH66F cells was higher than that into AH66 cells, although AH66F cells were less sensitive to PEP than AH66 cells. Deamide PEP was detected in intact cells which had taken up [3H]PEP-Cu(II) during 4 hours. This confirmed that PEP-Cu(II) was transported into the cell, the copper removed and PEP metabolized to deamide PEP. [3H]PEP-Cu(II) uptake into AH66 and AH66F cells increased in proportion to the extracellular concentration of drug up to at least 200 micrograms/ml, suggesting that uptake was not mediated by a carrier system. Metabolic inhibitors such as NaN3 and 2,4-dinitrophenol enhanced [3H]PEP-Cu(II) uptake, but did not influence efflux. Uptake was also enhanced by membrane modifiers such as dibucaine and chlorpromazine which increase the fluidity of lipid membranes. The results suggest that PEP-Cu(II) was taken up into tumor cells by passive diffusion, controlled by an energy-dependent cell membrane barrier.

Animals↗
PubMed1989

Role of DNA-binding in the cytotoxicity of an anthracycline, R20X2 and its morpholino analog, MX2.

3'-Deamino-3'-morpholino-13-deoxo-10-hydroxycarminomycin (MX2), a morpholino anthracycline derived from 13-deoxo-10-hydroxycarminomycin (R20X2) was 16 times less cytotoxic than R20X2 against cultured P388 leukemia cells. The reduced cytotoxicity of MX2 was not explainable by intracellular or intranuclear concentration of the drug or by its DNA-intercalating activity. Binding of MX2 and R20X2 to DNA was measured, after isolating the DNA fraction from an incubation mixture of the drugs with P388 cells or with calf thymus DNA. The amount of R20X2 bound to the DNA was obviously larger than that of MX2, and was dependent on incubation time. These data suggest that the poor binding activity of MX2 to DNA contributes to its reduced cytotoxicity.

Animals↗
PubMed1989

Altemicidin, a new acaricidal and antitumor substance. I. Taxonomy, fermentation, isolation and physico-chemical and biological properties.

Screening of new insecticidal and acaricidal antibiotics was carried out with reference to anti-brine shrimp activity from actinomycete strains isolated from marine environments. Of 200 actinomycete isolates, one isolate was found to produce a new substance, altemicidin. The strain was isolated from sea mud collected at Gamo, Miyagi Prefecture, Japan, and identified as Streptomyces sioyaensis SA-1758. Altemicidin was purified by Diaion CHP-20P and Sephadex LH-20 column chromatographies. The molecular formula was determined as C13H20N4O7S by elemental analysis, MS and 13C NMR spectrum. Altemicidin showed not only acaricidal activity but also antitumor activity. The compound showed no antimicrobial activity except the inhibitory activity to Xanthomonas strains.

Alkaloids↗
PubMed1989

Altemicidin, a new acaricidal and antitumor substance. II. Structure determination.

The structure of altemicidin, a new acaricidal and antitumor agent, was determined to be (1R,2S,3aR,7aS)-4-carbamoyl-2-hydroxy-6-methyl-1-(sulfamo ylacetamido)-2,3,3a,6, 7,7a-hexahydro-6-azaindene-1-carboxylic acid by a combination of spectroscopic and X-ray crystallographic analysis of its derivatives. Altemicidin is a monoterpene alkaloid.

Alkaloids↗
PubMed1989

Structure-activity relationship studies on 4''-O-acyltylosin derivatives: significance of their 23-O-mycinosyl and 4''-O-acyl moieties in antimicrobial activity against macrolide-resistant microbes.

Essential roles for both the 23-O-mycinosyl and 4''-O-acyl moieties of 4''-O-acyltylosin derivatives in the expression of antimicrobial activity against multiple macrolide-resistant strains of Staphylococci and mycoplasmas were demonstrated by in vitro comparison of the MICs of erythromycin, josamycin, tylosin and its 3- and 4''-O-acyl derivatives, demycinosyltylosin (DMT) and its 3- and 4''-O-acyl derivatives and 23-modified 3-O-acetyl-4''-O-isovaleryl-DMT derivatives.

Anti-Bacterial Agents↗
PubMed1989

Induction by herbimycin A of contact inhibition in v-src-expressed cells.

Herbimycin A, an inhibitor of pp60src tyrosin kinase, caused src oncogene-expressed cells to become sensitive to contact inhibition, but did not affect ras oncogene-expressed cells. The cell lines tested were temperature sensitive v-src- and temperature sensitive v-ras-integrated nontransformed rat kidney cell line (NRK) (srctsNRK and rastsNRK, respectively) and a wild-type v-src-integrated NIH3T3 (src3T3). srctsNRK cells in densely populated cultures (plated at 1.25 x 10(4) cells/cm2), grown at 33 degrees C in the presence of 0.45 micrograms/ml of herbimycin A, ceased the cell cycle at the G0-G1 stage within 2 days, and the cells showed normal morphology. Upon removal of herbimycin A, the quiescent cells resumed the cell cycle in concert with morphological alteration from 'normal' to 'transformed', and proceeded through the S and M stages successively in a synchronized manner. Cells in the late S stage, compared with those in other stages of the cell cycle, were more sensitive to the killing effect of 5-fluorodeoxyuridine. Such synchronism of the cell cycle was not observed with sparsely populated cultures (2.5 x 10(3) cells/cm2); the cells resumed their asynchronous growth after removal of herbimycin A, although their morphology returned to 'transformed' as in the experiment with the densely populated cultures. The induction by herbimycin A of contact inhibition in densely populated cultures was also observed with src3T3 (grown at 37 degrees C) but not with rastsNRK (grown at 33 degrees C).

Animals↗
PubMed1989

Effects of deoxyspergualin on hematopoiesis: studies of murine hematopoietic progenitor cell and peripheral blood cell levels.

The effect of a novel immunosuppressive agent, deoxyspergualin (DSG), on hematopoiesis in mice was studied with measurements of peripheral blood counts and assays of granulocyte-monocyte colony-forming cells (cfu-C) and spleen colony-forming cells (cfu-S) in bone marrow, during and after successive intraperitoneal administration of DSG. When DSG was administered at a strong immunosuppressive dose of 6.25 mg/kg daily for 15 days, mice developed significantly decreased peripheral blood counts and decreased bone marrow cells (BMC) during administration. After the completion of DSG administration a marked rebound in leukocytosis was observed and BMC returned to normal. In contrast, total cfu-C in the femur significantly increased during the DSG administration, and subsequently returned to normal. Moreover, total cfu-S in the femur were normally sustained in contrast with a decrease of BMC during the DSG administration. These findings suggest that DSG does not show generalized overt cytotoxicity against hematopoietic stem cells and freezes the ability of the stem cell in the proliferation or the differentiation.

Animals↗