Biomedical subjects

Hiroyuki Taguchi

Publications and source records attributed to Hiroyuki Taguchi.

10 recordsLinked to original sources

PubMed2005

Effects of poly(ethylene glycol) (PEG) concentration on the permeability of PEG-grafted liposomes.

Poly(ethylene glycol)-grafted liposomes (PEG-liposomes) were prepared from dipalmitoylphosphatidylcholine (DPPC) with various amounts of distearoyl-N-monomethoxy poly(ethylene glycol)-succinyl-phosphatidylethanolamines (DSPE-PEG) with PEG molecular weights of 1000, 2000, 3000 and 5000. The effects of DSPE-PEG concentration on the permeability of PEG-liposomes were investigated using carboxyfluorescein (CF). In the gel state, the CF leakage from PEG-liposomes was decreased with increasing mole fractions of DSPE-PEG for all PEG molecular weights. In the liquid-crystalline state, the CF leakage from PEG-liposomes containing DSPE-PEG1000 gradually increased with increasing mole fractions of DSPE-PEG, while that of PEG-liposomes whose molecular weight in PEG units was above 2000 rapidly decreased by the addition of DSPE-PEG. Furthermore, no effect of PEG molecular weight on CF leakage was observed. The relationship between the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) (or 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH)) and the mole fraction of DSPE-PEG for PEG-liposomes was also investigated. No significant changes in fluorescence polarization of DPH for liposomal bilayer membranes was observed in the gel and liquid-crystalline states due to the addition of DSPE-PEG, while that of TMA-DPH was decreased compared with that of liposomes without DSPE-PEG in both states.

Dose-Response Relationship, Drug↗

PubMed2005

Preparation and clinical application of indomethacin gel for medical treatment of stomatitis.

The preparation and clinical applications of indomethacin (IM) gel were investigated in the treatment of stomatitis resulting from chemotherapy and radiotherapy for cancer. IM gel was prepared by adding various water-soluble polymers [hydroxypropyl cellulose (HPC), etc.] to IM aqueous solution. The release rate of IM from IM gels was found to decrease with increasing polymer concentration and viscosity and to follow a first-order reaction rate equation. The release rate of IM from the IM gel with HPC was decreased gradually with increasing polymer concentration and to be easily controllable compared with gels with other polymers. The time before pain relief occurred after application of the IM gel was slightly shorter and the duration of pain relief was longer compared with the IM aqueous solution. It was confirmed that IM gel is useful in the treatment of stomatitis.

Administration, Topical↗

PubMed2004

A modified method using static head-space gas chromatography for determining the stability constants of 1-alkanol/alpha-cyclodextrin complexation.

A modification of the conventional static head-space gas chromatography method (SHSGC method) to determine stability constants for 1-alkanol/alpha-CD inclusion complexes was investigated. The 1 : 1 stability constants determined by this modified SHSGC method are in reasonable agreement with the corresponding values reported previously. The modified SHSGC method precludes the necessity of the calibration curve by the use of Henry's law constant of guest. Consequently, the modified SHSGC method is more advantageous than the conventional SHSGC method because the experimental time required for determination of the stability constant is markedly reduced.

Calibration↗

PubMed2003

Solubilization of (+)-limonene by anionic/cationic mixed surfactant systems.

The combined effects of sodium n-octyl sulfate (SOS) and cetyltrimethylammonium bromide (CTAB) on the solubilization of (+)-limonene in aqueous solution were studied using a headspace gas chromatography technique. The findings showed the mixing of SOS and CTAB resulted in positive synergistic effects on the solubility of (+)-limonene. The positive synergistic effects are explained from the perspective of the phase behavior of this mixed surfactant system.

Alkanesulfonic Acids↗

PubMed2003

Complexation of butylbenzenes with 2-hydroxypropyl-cyclodextrins in aqueous solution.

The stability constants for the inclusion of butylbenzenes (BBs) with 2-hydroxypropyl-cyclodextrins (2HP-CDs) in aqueous solution have been determined using the static head-space method. The 1:1 stability constants were obtained by this method. For the complexation of BBs by 2HP-alpha-CD, the order of stability constants was n-BB > isoBB > tert-BB. In contrast, the order for complexation of BBs by 2HP-beta-CD was the opposite: tert-BB > isoBB > n-BB. The order of the stability constants by 2HP-gamma-CD was similar to that of 2HP-beta-CD, but the values of the stability constants were not significantly different in the BB types. In addition, the binding effects are discussed in relation to the different alkyl groups of BBs.

2-Hydroxypropyl-beta-cyclodextrin↗

PubMed2003

Effects of poly(ethylene glycol) (PEG) chain length of PEG-lipid on the permeability of liposomal bilayer membranes.

The effects of poly(ethylene glycol) (PEG) chain length of PEG-lipid on the membrane characteristics of liposomes were investigated by differential scanning calorimetry (DSC), freeze-fracture electron microscopy (FFEM), fluorescence polarization measurement and permeability measurement using carboxyfluorescein (CF). PEG-liposomes were prepared from mixtures of dipalmitoyl phosphatidylcholine (DPPC) and distearoyl phosphatidylethanolamines with covalently attached PEG molecular weights of 1000, 2000, 3000 and 5000 (DSPE-PEG). DSC and FFEM results showed that the addition of DSPE-PEG to DPPC in the preparation of liposomes caused the lateral phase separation both in the gel and liquid-crystalline states. The fluidity in the hydrocarbon region of liposomal bilayer membranes was not significantly changed by the addition of DSPE-PEG, while that in the interfacial region was markedly increased. From these results, it was anticipated that the CF leakage from PEG-liposomes is accelerated compared with DPPC liposomes. However, CF leakage from liposomes containing DSPE-PEG with a 0.060 mol fraction was depressed compared with regular liposomes, and the leakage decreased with increasing PEG chain length. Furthermore, the CF leakage from liposomes containing DSPE-PEG with a 0.145 mol fraction was slightly increased compared with that of liposomes containing DSPE-PEG with a 0.060 mol fraction. It is suggested that the solute permeability from the PEG-liposomes was affected by not only properties of the liposomal bilayer membranes such as phase transition temperature, phase separation and membrane fluidity, but also the PEG chain of the liposomal surface.

Lipid Bilayers↗

PubMed2003

Primary structure of cytochrome c gene from the white root rot fungus Rosellinia necatrix.

The nucleotide sequence of the cytochrome c (CytC) gene of the white root rot fungus Rosellinia necatrix was analyzed. The structure of this gene, which had three introns in the coding region, was similar to that of Aspergillus nidulans. The second intron of the R. necatrix CytC gene was not present in Neurospora crassa or Fusarium oxysporum. However, the amino acid sequence of R. necatrix was most similar to that of Neurospora crassa. Thus, it seemed that the second intron of the R. necatrix CytC gene was inserted into its present position after R. necatrix and its closest relatives diverged evolutionarily.

Amino Acid Sequence↗

PubMed2002

Dietary diacylglycerol suppresses high fat diet-induced hepatic fat accumulation and microsomal triacylglycerol transfer protein activity in rats.

We have recently shown that the long-term ingestion of dietary diacylglycerol (DAG) mainly containing 1,3-isoform reduces body fat accumulation in humans as compared to triacylglycerol (TAG) with the same fatty acid composition. The fat reduction in this human experiment was most pronounced in visceral fat and hepatic fat. Recent animal studies have also indicated that dietary DAG induces alteration of lipid metabolism in the rat liver. In the present study, the dietary effects of DAG on high fat diet-induced hepatic fat accumulation and hepatic microsomal triglyceride transfer protein (MTP) activity were examined in comparison with those of TAG diet in rats. When the TAG oil content was increased from 10 to 30 g/100 g diet, hepatic TAG concentration, hepatic MTP activity and MTP large subunit mRNA levels were significantly increased after 21 days. However, when the dietary TAG oil (30 g/100 g diet) was replaced with the same concentration of DAG oil with the same fatty acid composition, the increase of the TAG concentration and the MTP activity in the liver were significantly less and the mRNA levels remained unchanged. The MTP activity levels correlated significantly with hepatic TAG concentration.These results showed that dietary DAG may suppress high fat diet-induced MTP activity in the liver, and indicated the possibility that hepatic TAG concentration may regulate hepatic MTP activity.

Journal Article↗

PubMed2002

Primary structure of the histone 2B gene in the white root rot fungus, Rosellinia necatrix.

The nucleotide sequence of the histone 2B (H2B) gene in the white root rot fungus, Rosellinia necatrix, was determined. The gene has two introns in the coding region at positions conserved in the Neurospora crassa and Aspergillus nidulans H2B genes, but the third intron present in the H2B gene from N. crassa and A. nidulans is absent in the R. necatrix H2B gene. The amino acid sequence of the coding region of the R. necatrix gene resembled that of N. crassa and A. nidulans. Therefore, the third intron in the H2B gene of N. crassa and A. nidulans may have been inserted into the present position after species diversification.

Amino Acid Sequence↗

PubMed2002

[Microbiological evaluation of Helicobacter pylori stool antigen detection (HpSA) kit; its specificity and reactivity with coccoid form of H. pylori].

Helicobacter pylori stool antigen detection kit (HpSA) was microbiologically evaluated. All of the 10 strains of H. pylori showed positive result in HpSA test, but other bacteria of 16 species and 18 strains did not. In addition, the coccoid form of 10 H. pylori strains reacted positively with the HpSA kit as well as the helical form, although the OD450 value was slightly lower than that of helical form in 7 out of 10 strains examined. The minimum number of H. pylori showing positive reaction in HpSA test was 7.0 x 10(3) cfu. Feces of both conventional and germ free mice inhibited partially the reaction of H. pylori with HpSA kit, but this decrease in the reactivity was recovered by freeze-thawing of the feces. In contrast, freeze-thawing of the mice feces with H. pylori decreased the sensitivity in HpSA test, but it was also shown that coccoid form had a stronger reactivity than helical form. These results indicate that the HpSA kit is a rapid and useful diagnostic method for detection of H. pylori, particularly its coccoid form, in the fecal specimens.

Animals↗