Biomedical subjects

Takumi Tanaka

Publications and source records attributed to Takumi Tanaka.

4 recordsLinked to original sources

PubMed2006

Serum carboxypeptidase A activity as a biomarker for early-stage pancreatic carcinoma.

BACKGROUND: The early stage of pancreatic carcinoma lacks typical clinical signs and symptoms, and is difficult to diagnose. We developed an assay for active form of serum carboxypeptidase A (F-CPA) and its zymogen precursor pro CPA, and evaluated them as a marker for early-stage pancreatic carcinoma. METHODS: Serum CPA from 406 patients including 169 with pancreatic carcinoma, 53 with acute pancreatitis, 23 with chronic pancreatitis, and 161 with non-pancreatic diseases were assayed by a method with N-acetyl-phenylalanyl-l-3-thiaphenylalanine as substrate and dl-benzylsuccinic acid as specific inhibitor of CPA. Activation of pro CPA was carried out using trypsin. RESULTS: An established assay system was performed fully automatically and possesses enough performance for routine clinical assay. This system requires 31 minutes for CPA detection. No significant differences were detected between the F-CPA activity of patients with pancreatic carcinoma and that of patients with non-pancreatic diseases (p=0.168). F-CPA was mainly increased in patients with pancreatitis. Since total-CPA (T-CPA, T-CPA=pro CPA+F-CPA) was increased both in patients with pancreatic carcinoma and those with acute pancreatitis (p<0.0001, each case), the F-CPA/T-CPA ratio was low only in the patients with pancreatic carcinoma. The rate of positivity of T-CPA in the early stage of pancreatic carcinoma in which tumor was less than 2 cm was 77%, and higher than those of CA19-9 (31%), CEA (8%), and elastase 1 (46%). CONCLUSION: It was suggested that assays of both T-CPA and F-CPA in serum might be useful for the surveillance of early-stage pancreatic carcinoma.

Biomarkers, Tumor↗

PubMed2005

Quantitative microarray-based DNA-DNA hybridization assay for measuring genetic distances among bacterial species and its application to the identification of family Enterobacteriaceae.

Quantitative DNA-DNA hybridization to measure the genetic distances among bacterial species is indispensable for taxonomical determination. In the current studies, we developed a method to determine bacterial DNA relatedness on a glass microarray. Reference DNAs representing a total 93 species of Enterobacteriaceae were arrayed on a glass microplate, and signal intensities were measured after 2 hr of hybridization with Cy3-labeled bacterial DNAs. All immobilized DNAs from members of the family Enterobacteriaceae were identified by this method except for DNAs from Yersinia pseudotuberculosis and Y. pestis. These results suggest that quantitative microarray hybridization could be an alternative to conventional DNA-DNA hybridization for measuring chromosome relatedness among bacterial species.

DNA, Bacterial↗

PubMed2003

Quantitative filtration-blotting of protein in the presence of sodium dodecyl sulfate and its use for protein assay.

It is thought that sodium dodecyl sulfate (SDS), an anionic detergent, binds to hydrophobic moieties of peptide to destroy the conformational structure of protein. Because of this property, it is involved in many biochemical procedures such as separations of protein and proteolytic digestion. In the course of our study on a solid-phase protein assay, we found that SDS acts as an effective reagent for protein blotting onto a hydrophobic membrane of polyvinylidene difluoride with a manifold dot-blot apparatus. At least 0.1% SDS in an acid-ethanol blotting solution, while reducing the bias of pronounced interferers for protein assay to protein-membrane interaction, quantitatively retains protein on the membrane. Presumably, protein denatures by SDS to become an unfolded state and adsorbs into the membrane by hydrophobic interaction, even in the presence of excess SDS. Therefore, bolts stained with a pyrogallol red-molybdate complex (Pyromolex) reagent unreactive to the membrane allowed a precise protein determination without significant interference of materials, especially detergents in the sample solution. The filtration-blotting with SDS would be a crucial procedure for quantitative analyses such as immunoblotting in detergent-containing samples, together with the solid-phase protein assay with limited sample volumes, such as 20 microL or less.

Chemistry Techniques, Analytical↗

PubMed2003

Use of transcriptional sequencing in difficult to read areas of the genome.

In genome and cDNA sequencing projects, current cycle sequencing often encounters difficult-to-sequence templates which have unique secondary structures due to GC-rich composition or repeated regions. Due to the formation of stable secondary structures, remarkable decreases in fluorescent signals are observed in cycle sequencing reactions. It is not easy to determine the nucleotide sequences of these regions. Although several modifications of sequencing reactions have been tried to overcome these problems, some unreadable regions remain as gaps in genome sequencing projects. Here, we further developed transcriptional sequencing technology and evaluated the sequencing accuracy in these regions. The method was successively applied to artificial GC cluster templates and putative secondary structure-forming templates from genomic and cDNA clones. Our results indicate that transcriptional sequencing is a powerful and accurate method for GC-rich regions, simple sequence repeats, hairpins (inverted repeats), tandem repeat DNA templates, and gap-closing in draft sequencing data.

Animals↗