Biomedical subjects

Toshiyuki Ito

Publications and source records attributed to Toshiyuki Ito.

4 recordsLinked to original sources

PubMed2006

Detection of single-base mismatch at distal end of DNA duplex by electrochemical impedance spectroscopy.

Herein, we report an anomalous electrochemical behavior of surface-bound DNA duplex that has single-base mismatches at its distal end. Single-stranded 15-base DNA was immobilized at its 5'end onto gold electrode surfaces. After hybridization with complementary or mismatched DNA, electrochemical impedance spectra were obtained using [Fe(CN)(6)]3-/4- as redox marker ions. Hybridization with the complementary DNA reduced the charge-transfer resistance (R(CT)), whereas single-base mismatches at the distal end of the duplex largely increased the R(CT). This anomaly was found only with the distal end: the increase in R(CT) was not observed for mismatches at either the middle or the proximal end. These results indicate that electrochemical detection of single-base alterations at an end of sample DNA is exceptionally easy because of the diametrically opposite responses. This detection principle is promising for the typing of single-nucleotide polymorphisms in combination with the single-base primer extension protocol.

Base Pair Mismatch↗

PubMed2005

Autonomous polymer loading and sample injection for microchip electrophoresis.

We have developed an extremely simple method for microchip electrophoresis. Loading of a sieving polymer solution and injection of a sample solution are autonomously executed by a microchip fabricated in poly(dimethylsiloxane) (PDMS). In advance, the energy for the fluid pumping is stored in bulk PDMS by evacuating air dissolved in PDMS, and the information for the sample plug regulation is coded into the microchannel design. Besides the simplicity, our method brings about an advantageous effect: sample compaction due to the discontinuous electrophoretic mobility at the sample/polymer interface. The sample compaction effect was moderate in ordinary size-dependent separation for double-stranded DNA and was extreme in affinity electrophoresis for single-stranded DNA (ssDNA). In the latter separation mode, ssDNA components were sequence-specifically separated by difference in affinity to a probe oligonucleotide immobilized to the sieving polymer matrix. We separated up to 60-mer ssDNA mixtures based on single-base substitutions. The separation processes included typically 100-fold sample compaction and were completed within 15-30 s. This technology provides easy, simple, and sensitive method for detection of gene point mutations and typing of single-nucleotide polymorphisms.

Base Sequence↗

PubMed2003

A role of Helicobacter pylori infection in the development of duodenal ulcer after adult living-related liver transplantation.

Gastrointestinal bleeding caused by peptic ulcer disease is one of the serious complications of living-related liver transplantation (LRLT). The aim of this study was to clarify the factors involved in peptic ulcer formation in adult LRLT recipients. Forty consecutive adult LRLT recipients without a history of peptic ulcer disease were studied. Twenty-five patients (62.5%) tested positive for Helicobacter pylori. After LRLT, duodenal ulcer (DU) developed in six patients, and all of them tested positive for H. pylori. In contrast, none of the H. pylori-negative patients developed DU. Preoperative serum gastrin levels in patients with DU were significantly higher than in those without DU, irrespective of H. pylori infection. Preoperative pepsinogen I levels in patients with DU were significantly higher than in those without DU with H. pylori infection. These data suggest involvement of H. pylori infection in the development of DU after LRLT. Eradication of H. pylori may prevent the development of DU after LRLT particularly in patients with hypergastrinemia and high serum pepsinogen I.

Adult↗

PubMed2002

[Dystrophin gene analysis on 76 families with dystrophinopathy].

We report for the last 1 year and 9 months results of the molecular diagnosis of Duchenne (DMD) and Becker (BMD) muscular dystrophy at Kobe University. Analysis was done on 87 patients belonging to 76 families (66 DMD cases, 10 BMD cases). We first determined the presence of deletions or duplications using Southern blot analysis. Then analyzed small mutations (point mutations or small deletions/insertions) by mRNA analysis using RT-PCR and direct sequencing. 69 mutations (89.5%) were found, 46 deletions (60.5%), 5 duplications (6.6%) and 17 point mutations (22.4%) including 15 nonsense mutation. mRNA analysis from lymphocytes or muscle was useful for screening patients without a mutation identifiable by Southern blot analysis.

Dystrophin↗