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Tomofumi Santa

Publications and source records attributed to Tomofumi Santa.

At least 19 recordsLinked to original sources
PubMed2007

Synthesis and fluorescent properties of bi- and tricyclic 4-N-carbamoyldeoxycytidine derivatives.

New bi- and tricyclic deoxycytidine derivatives (dChpd, dCmpp, dCtpp, dCppp) were synthesized as analogues of a fluorescent nucleoside, dChpp, previously reported. The carbamoyl group of dChpd and the 5-position of the cytosine ring are bridged via an ethylene linker so that the modified group forms a nonplanar structure with the cytosine ring. The fluorescent study of dChpd indicated that the coplanar structure between the carbamoyl group and the cytosine ring is of importance. N-Methylation of the carbamoyl group (dCmpp) weakened the intensity of the fluorescence of dChpp, and the derivative (dCtpp), which had a thiocarbamoyl group, lost its fluorescent property. Moreover, addition of a pyrrolo-ring (dCppp) to dChpp enhanced the intensity of fluorescence, and an emission light was observed with a marked Stokes shift of 120 nm.

Deoxycytidine↗
PubMed2006

Depletion of serotonin selectively impairs short-term memory without affecting long-term memory in odor learning in the terrestrial slug Limax valentianus.

The terrestrial slug Limax is able to acquire short-term and long-term memories during aversive odor-taste associative learning. We investigated the effect of the selective serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) on memory. Behavioral studies indicated that 5,7-DHT impaired short-term memory but not long-term memory. HPLC (high-performance liquid chromatography) analysis revealed that 5,7-DHT significantly reduced serotonin content in the central nervous system. The present study suggests that acquisition, retention, and/or retrieval of short-term memory involves serotonin, and neither acquisition nor retrieval of long-term memory requires serotonin at a level as high as that required for short-term memory.

5,7-Dihydroxytryptamine↗
PubMed2006

Synthesis and properties of a new fluorescent bicyclic 4-N-carbamoyldeoxycytidine derivative.

[reaction: see text] A bicyclic 4-N-carbamoyldeoxycytidine derivative (1, dC(hpp)) geometrically locked was synthesized as a new fluorescent nucleobase. The hybridization properties of oligodeoxynucleotides containing dC(hpp) were investigated by use of T(m) analysis. It was found that dC(hpp) forms stable base pairs not only with the complementary guanine base, but also with the adenine base. Interestingly, the fluorescence of dC(hpp) was suppressed only when a dC(hpp)-dG base pair was formed.

Base Pairing↗
PubMed2006

Synthesis of the isotope-labeled derivatization reagent for carboxylic acids, 7-(N,N-dimethylaminosulfonyl)-4-(aminoethyl)piperazino-2,1,3-benzoxadiazole (d6) [DBD-PZ-NH2 (D)], and its application to the quantification and the determination of relative amount of fatty acids in rat plasma samples by high-performance liquid chromatography/mass spectrometry.

The isotope-labeled benzofurazan derivatization reagent for carboxylic acids, 7-(N,N-dimethylaminosulfonyl)-4-(aminoethyl)piperazino-2,1,3-benzoxadiazole (d6) [DBD-PZ-NH2 (D)] was synthesized. DBD-PZ-NH2 (D) was used for the accurate quantification of fatty acids by liquid chromatography/mass spectrometry (LC/MS). The standard fatty acids were derivatized with DBD-PZ-NH2 (D) to the stable isotope-labeled compounds for the fatty acids derivatives of DBD-PZ-NH2 and used for the internal standards. The obtained calibration curves for fatty acids were linear over the range 0.1-200 microM (r2 > 0.999). Fatty acids in plasma samples were determined after derivatization with DBD-PZ-NH2 and analyzed by LC/MS using standard fatty acid DBD-PZ-NH2 (D) derivatives as internal standards. Furthermore, the relative amounts of fatty acids in two plasma samples were determined after derivatization with DBD-PZ-NH2 and DBD-PZ-NH2) (D). The isotope-labeled derivatization reagent was useful for accurate quantification and the determination of relative amounts of the metabolites in biological samples having the target functional group.

Animals↗
PubMed2006

A further study on the combined use of internal standard and isotope-labeled derivatization reagent for expansion of linear dynamic ranges in liquid chromatography-electrospray mass spectrometry.

The combined use of a so-called internal standard and the isotope-labeled derivatization reagent for the quantification of analytes for liquid chromatography-mass spectrometry (LC/MS) was further studied. The sample solution (containing the analytes and an internal standard) was derivatized with the light form of the derivatization reagent, 7-(N,N-dimethylaminosulfonyl)-4-(aminoethyl)piperazino-2,1,3-benzoxadiazole (DBD-PZ-NH(2)) or 7-(N,N-dimethylaminosulfonyl)-4-piperazino-2,1,3-benzoxadiazole (DBD-PZ). A standard solution of the analytes (containing an internal standard) was derivatized with the isotope (d(6))-labeled derivatization reagent, DBD-PZ-NH(2) (D) or DBD-PZ (D), and served as the isotope-labeled internal standards. The peak heights of the targeted analytes derivatives in the sample solution were corrected using those of the internal standard and the heavy form derivatives of the standards, and the calibration curves were constructed. The curve bending of the calibration curves caused by the ion suppression at the ion source was suppressed and the linear dynamic ranges of the calibration curves were expanded. The derivatives of DBD-PZ-NH(2) were about 10 times more sensitively detected than those of DBD-PZ derivatives and, therefore, DBD-PZ-NH(2) might be suitable for sensitive detection.

Chromatography, Liquid↗
PubMed2006

Synthesis of fluorescent cyclic cytosine nucleosides and their fluorescent properties upon incorporation into oligonucleotides.

We report here the synthesis and spectroscopic characterization of a new fluorescent pyrimidopyrimidoindole nucleoside derivative (dC(PPI)) modified at the cytosine base. The photophysical properties of dC(PPI) were examined by fluorescent spectroscopy and quantum chemical calculations. It was found that dC(PPI)-labeled oligonucleotides gave almost the same thermal stability as that of the corresponding unmodified sequences. In addition, the quantum yield of dC(PPI) in the double-stranded state was significantly higher than that in the single-stranded state.

DNA Probes↗
PubMed2005

Development of an HPLC-fluorescence determination method for carboxylic acids related to the tricarboxylic acid cycle as a metabolome tool.

We report the simultaneous determination of the carboxylic acids related to the tricarboxylic acid (TCA) cycle, which plays an important role in producing adenosine triphosphate (ATP) and generating energy in mitochondria. Seven carboxylic acids from the TCA cycle, and pyruvic acid and 2-methylsuccinic acid, as an internal standard, were derivatized with a fluorescent reagent for carboxyl groups, 4-N,N-dimethylaminosulfonyl-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ), in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and 4-N,N-dimethyaminopyridine as the coupling reagents, at 60 degrees C for 120 min. Subsequently, the excess DBD-PZ was removed efficiently using a cation-exchange cartridge, SDB-RPS (Empore). These fluorescent derivatives were separated well from each other on an octadecyl silica column (TSKgel ODS-80Ts, 250 x 4.6 mm, i.d.) with an eluent of acetonitrile-water containing 1% formic acid at a flow rate of 0.8 mL/min, and were detected fluorometrically at 560 nm, with excitation at 450 nm. The validation data were satisfactory in the range of 2.5-100 microm citric acid, isocitric acid, 2-oxoglutaric acid, succinic acid and fumaric acid. The detection limit (S/N = 3) for citric acid was 2 fmol on the column. The structures of these derivatives were confirmed by high-performance liquid chromatography-mass spectrometry, which proved that their carboxylic groups were completely labeled with DBD-PZ, except for oxaloacetic acid. This HPLC method was successfully applied to the analysis of TCA cycle metabolites in rat urine. The method will also be useful for metabolome research, such as for target analyses of metabolites with carboxyl groups, not only in urine but also in cells and organs.

Animals↗
PubMed2005

Synthesis of benzofurazan derivatization reagents for carboxylic acids and its application to analysis of fatty acids in rat plasma by high-performance liquid chromatography-electrospray ionization mass spectrometry.

The derivatization regents for carboxylic acids, DAABD-AE (4-[2-(N,N-dimethylamino)ethylaminosulfonyl]7-(2-aminoethylamino)-2,1,3-benzoxadiazole), MePZBD-AE ([4-(4-N-methyl)piperazinosulfonyl]-7-(2-aminoethylamino)-2,1,3-benzoxadiazole) and APZBD-NHMe ([4-(4-N-aminoethyl)piperazinosulfonyl]-7-methylamino-2,1,3-benzoxadiazole) were developed for electrospray ionization-mass spectrometry (ESI-MS). The derivatization reaction with fatty acids was completed at 60 degrees C within 30 min. The derivatives of fatty acids were separated on a reversed-phase column and detected with ESI-MS. The detection limits attained for fatty acids were femtomol range and the calibration curves were linear over the range from 0.1 to 100 pmol (r2 > 0.992) for DAABD-AE and MePZBD-AE. DAABD-NHMe was applied to the analysis of fatty acids in rat plasma samples.

Animals↗
PubMed2005

Effects of molecular mass and hydrophobicity on transport rates through non-specific pathways of the silkworm larva midgut.

We previously reported that therapeutic drug effects in the silkworm infection model are largely influenced by midgut permeability. In this report, we describe the effects of drug molecular mass and hydrophobicity on transport through the silkworm larva midgut membrane. Hydrophilic compounds with a molecular mass of greater than 400Da did not permeate the silkworm larva midgut, and the hydrophobicity of similar-sized compounds had positive effects on the transport rate. Furthermore, we compared transport rates through the midgut membrane between cefcapene sodium (CFPN-Na) and cefcapene pivoxil (CFPN-PI), which is a CFPN-Na prodrug. The in vitro transport rate of CFPN-PI was three times faster than that of CFPN-Na. Moreover, when CFPN-PI and CFPN-Na were injected into the living silkworm larva midgut, CFPN-PI appeared rapidly in the haemolymph, whereas CFPN-Na did not. The 50% effective dose (ED50) of CFPN-PI administered via the midgut was one-sixth that of CFPN-Na. These findings suggest that the general features of the non-specific transport route are similar between silkworm larvae and mammals.

Animals↗
PubMed2005

Amelioration of vascular endothelial dysfunction in obstructive sleep apnea syndrome by nasal continuous positive airway pressure--possible involvement of nitric oxide and asymmetric NG, NG-dimethylarginine.

BACKGROUND: Asymmetric NG,NG-dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide (NO) synthase and its plasma concentration is elevated in patients with cardiovascular risk factors, including hyperlipidemia, hypertension, diabetes, and hyperhomocysteinemia. Obstructive sleep apnea syndrome (OSAS) has been attracting attention as a risk factor for cardiovascular disorders because it often accompanies hypertension, obesity, glucose impairment, and dyslipidemia, all of which are factors in metabolic syndrome and risk factors for cardiovascular disease. METHODS AND RESULTS: In the present study, flow-mediated vasodilatation (FMD) of the brachial artery and plasma concentrations of ADMA were measured before and after nasal continuous positive airway pressure (nCPAP) therapy, which abrogates apnea, in 10 male patients aged 36-69 years old, who were given a diagnosis of OSAS by polysomnography. The percent FMD (%FMD) improved significantly from 3.3+/-0.3% to 5.8+/-0.4% (p<0.01) and 6.6+/-0.3% (p<0.01), before, 1 week, and 4 weeks after nCPAP, respectively. At the same time, the plasma NOx concentrations, metabolites of NO, tended to increase, but the plasma ADMA concentration decreased inversely to %FMD and NOx. A negative correlation between %FMD and plasma ADMA concentration, and a positive correlation between %FMD and plasma NOx concentrations were observed. CONCLUSION: Nasal CPAP improves endothelial function, in part by the decreasing ADMA concentration, thereby potentiating NO production.

Adult↗
PubMed2004

Determination of rat blood S-D-lactoylglutathione by a column-switching high-performance liquid chromatography with precolumn fluorescence derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole.

A method for the determination of S-d-lactoylglutathione (SLG), an intermediate metabolite of the glyoxalase system, in rat blood is described. After hemolysis and deproteinization of 30 microl of rat blood, SLG in the blood was determined by a column-switching HPLC system with precolumn fluorescence derivatization with a fluorogenic reagent, 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F). Calibration curves for the determination of SLG showed a good linearity (r2 > 0.999) over the range of 20-100 pmol SLG spiked in rat blood samples. The accuracy was in the range of 97-104% (20-100 pmol SLG spiked in rat blood sample, N = 4). The detection limit was 8.12 fmol, and the quantitation limit was 27.07 fmol, respectively. The intra- and interday coefficients of variance were 4.63% (N = 5) and 9.98% (N = 5), respectively. The concentrations of SLG in whole blood from male Wistar-Kyoto rats (12 weeks old) were 3.48+/-0.78 microM (N = 4, mean+/-SE). In streptozotocin-induced diabetic rats, the concentration of SLG was significantly increased, approx 5-fold, compared with normal rats, suggesting that the metabolic flux of the glyoxalase system increases in red blood cells during hyperglycemia.

4-Chloro-7-nitrobenzofurazan↗
PubMed2004

Fluorogenic derivatization reagents suitable for isolation and identification of cysteine-containing proteins utilizing high-performance liquid chromatography-tandem mass spectrometry.

The fluorogenic derivatization reagents with a positive charge, 4-(dimethylaminoethylaminosulfonyl)-7-chloro-2,1,3-benzoxadiazole (DAABD-Cl) and 7-chloro-2,1,3-benzoxadiazole-4-sulfonylaminoethyltrimethylammonium chloride (TAABD-Cl), are proposed for use in proteomics studies. Following derivatization of protein mixtures with these reagents, a series of standard processes of isolation, digestion, and identification of the proteins were performed utilizing high-performance liquid chromatography-fluorescence detection and tandem mass spectrometry with the probability-based protein identification algorithm. Both DAABD and TAABD derivatives were detected fluorometrically at the femtomole level and showed more than 100-fold improvement in sensitivity compared to the underivatized original compounds with an electrospray ionization ion trap mass spectrometer analysis. The modification of the MASCOT database search system memorized with the fragment information of a DAABD-attached Cys residue allowed the identification of the proteolytic peptide fragments of the derivatized bovine serum albumin (BSA) with an estimated 38% sequence coverage of BSA. Utilizing DAABD-Cl as a derivatization reagent, identification of several proteins was also possible in a soluble extract of Caenorhabditis elegans (10 microg of protein). Consequently, for identification of proteins in the complex matrixes of proteins, DAABD-Cl could be a more appropriate reagent than ammonium 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate as reported previously.

Animals↗
PubMed2004

A fully automated amino acid analyzer using NBD-F as a fluorescent derivatization reagent.

A fully automated amino acid analyzer using NBD-F (4- fluoro-7-nitro-2,1,3-benzoxadiazole) as a fluorescent derivatization reagent was developed. The whole analytical process was fully automated from derivatization, injection to HPLC separation and quantitation. The derivatization reaction conditions were re-evaluated and optimized. Amino acids were derivatized by NBD-F for 40 min at room temperature in the borate buffer (pH 9.5). The derivatives were separated within 100 min and fluorometrically detected at 540 nm with excitation at 470 nm. The detection limits for amino acids were in the range of 2.8-20 fmol. The calibration curves were linear over the range of 20 fmol to 20 pmol on column with the correlation coefficients of 0.999. The coefficients of variation were less than 5% at 3 pmol injection for all amino acids. Amino acids in rat plasma were determined by the proposed HPLC method.

4-Chloro-7-nitrobenzofurazan↗
PubMed2004

An automated analyzer for vancomycin in plasma samples by column-switching high-performance liquid chromatography with UV detection.

An automated analyzer for vancomycin in rat plasma by column-switching high-performance liquid chromatography (HPLC) with UV detection was developed. The method includes in-line extraction of vancomycin by ion-exchange cartridge column and a separation on a reversed-phase column with UV detection at 215 nm. Plasma samples were diluted by mobile phase solution and directly injected to HPLC. Vancomycin was quantitatively recovered from rat plasma samples. The separation was completed within 15 min. The calibration curve was linear over the range from 0.5 to 100 microg/mL with the detection and quantification limits of 0.5 microg/mL (2.5 ng on column; signal-to-noise ratio = 3). The values of precision in intra- and inter-day assays (n = 3) were less than 1.92 and 3.69%, respectively. This method does not require time-consuming pre-treatment and is suitable for the routine assay of plasma samples.

Animals↗
PubMed2004

Quantitative evaluation of the therapeutic effects of antibiotics using silkworms infected with human pathogenic microorganisms.

The injection of bacteria (Staphylococcus aureus, Stenotrophomonas maltophilia) or true fungi (Candida albicans, Candida tropicalis) that are pathogenic to humans into the silkworm hemolymph leads to death of the larvae within 2 days. Antibiotics used for clinical purposes have therapeutic effects on silkworms infected with these pathogens. The 50% effective doses obtained by injection into the silkworm hemolymph are consistent with those reported for mice. Injection of vancomycin and kanamycin into the silkworm hemolymph was effective, but oral administration was not. Chloramphenicol, which is effective by oral administration, appeared in the silkworm hemolymph soon after injection into the midgut, whereas vancomycin did not. Isolated midgut membranes were impermeable to vancomycin. Thus, the ineffectiveness of oral administration of vancomycin to silkworms is due to a lack of intestinal absorption.

Administration, Oral↗
PubMed2003

Capillary electrophoresis with laser induced-fluorescence detection of profens derivatized with the water-soluble fluorogenic reagent 4-N-(4-N'-aminoethyl)piperazino-7-nitro-2,1,3-benzoxadiazole.

Profens, including pranoprofen, fenoprofen, flurbiprofen, ketoprofen and ibuprofen (Ib), were derivatized by a water-soluble benzofurazan fluorescent reagent, 4-N-(4-N'-aminoethyl)piperazino-7-nitro-2,1,3-benzoxadiazole and then were run on capillary electrophoresis in a NH4Ac-HAc buffer of pH 3.1 containing 2.4 mM beta-cyclodextrin. At room temperature, the derivatization reaction was catalyzed by triphenyl phosphine and diphenyl disulfide in acetonitrile medium, and the derivatives fluoresce around 530 nm when excited at 488 nm. With the CE running on a 50 cm x 50 microm I.D. length fused-silica capillary of by using Ar+ laser induced-fluorescence detection, the detection limits attained were in the range of 0.16 to 0.3 fmol.

4-Chloro-7-nitrobenzofurazan↗
PubMed2003

First fluorescent photoinduced electron transfer (PET) reagent for hydroperoxides.

A novel fluorescent reagent for hydroperoxides, 4-(2-diphenylphosphinoethylamino)-7-nitro-2,1,3-benzoxadiazole (1), was developed on the basis of the method for designing photoinduced electron transfer (PET) reagents having a benzofurazan skeleton. Compound 1 was quantitatively reacted with hydroperoxides to give its fluorescent derivative, 2. In acetonitrile, the Phi value (0.44) of 2 was 31 times greater than that of 1. The long excitation (458 nm) and emission (520 nm) wavelengths of 2 are suitable for the determination of hydroperoxides, especially in biosamples. [structure: see text]

Fluorescence Resonance Energy Transfer↗