Biomedical subjects

Atsushi Narita

Publications and source records attributed to Atsushi Narita.

7 recordsLinked to original sources

PubMed2025

Plasma Proteomic Profiles of Pediatric Patients With Human Herpesvirus 6B Encephalitis Following Umbilical Cord Blood Transplantation.

Human herpesvirus 6B (HHV-6B) encephalitis is a rare but severe complication of hematopoietic cell transplantation. This study investigated the pathogenesis of HHV-6B encephalitis by comparing plasma proteomic profiles of four pediatric patients with HHV-6B encephalitis to three with asymptomatic HHV-6B reactivation following umbilical cord blood transplantation (UCBT). Plasma proteomic profiling was conducted using liquid chromatography-mass spectrometry. Overall, 260 proteins were identified and quantified in plasma samples. At the onset of HHV-6B encephalitis and asymptomatic reactivation, 20 and 24 proteins, respectively, were significantly upregulated compared to their respective pre-onset levels. Of these, 11 proteins were uniquely upregulated in HHV-6B encephalitis. S100-A9 and S100-A8 were the most and second-most upregulated proteins in HHV-6B encephalitis, respectively. Elevated plasma S100A8/A9 heterodimer levels were confirmed via enzyme-linked immunosorbent assay in three of the four patients with HHV-6B encephalitis. Pathway analysis identified neutrophil degranulation as the most enriched category among upregulated proteins in HHV-6B encephalitis. Additionally, proteins related to the protein-lipid complex remodeling pathway were more prominently upregulated in HHV-6B encephalitis than in asymptomatic reactivation. Proteomic analysis revealed distinct plasma protein profiles between HHV-6B encephalitis and asymptomatic HHV-6B reactivation in pediatric UCBT recipients. The inflammatory response mediated by S100A8/A9 proteins may play a critical role in the pathogenesis of HHV-6B encephalitis. These findings indicate that proteomic analysis may provide novel insights into the host response to HHV-6B reactivation and the subsequent development of HHV-6B encephalitis.

Humans↗

PubMed2006

Visible sensing of nucleic acid sequences with a genetically encodable unmodified RNA probe.

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Base Sequence↗

PubMed2006

Visible sensing of nucleic acid sequences using a genetically encodable unmodified mRNA probe.

We previously reported a molecular beacon-mRNA (MB-mRNA) strategy for nucleic acid detection/sensing in a cell-free translation system using unmodified RNA as a probe. Here in this presentation, we report that a combination with RNase H activity, which induces an additional process of irreversible cleavage of MB-domain, achieves an improved sequence selectivity (one nucleotide selectivity) and an enhanced sensitivity. This improved system finally enabled visible sensing of target nucleic acid sequence at a single nucleotide resolution under isothermal conditions.

Base Sequence↗

PubMed2005

Doubly catalytic sensing of HIV-1-related CCR5 sequence in prokaryotic cell-free translation system using riboregulator-controlled luciferase activity.

A molecular-beacon-type riboregulator (mRNA) was applied to multiply catalytic gene sensing. It consists of a reporter gene for firefly protein luciferase and, upstream thereof, a regulator hairpin domain composed of an RBS/anti-RBS stem (RBS = ribosome binding site) and a loop which is complementary to the target. The hairpin and, hence, the RBS are rendered open upon binding of a target oligonucleotide of the human CC chemokine receptor 5 sequence in a prokaryotic cell-free translation system (10 muL) to ignite ribosomal catalytic translation, or transcription/translation when using a DNA form of the probe, to produce luciferase, which is assayed by a catalytic chemiluminescence reaction. The sensing, using an unmodified RNA or even dsDNA as a probe with a chemiluminescence output, is thus doubly catalytic or amplifiable with a sensitivity at </=50 fmol in respect to the target with 4.5 fmol (1 ng/muL) of probe and a single nucleotide resolution.

Base Sequence↗

PubMed2005

Locked TASC probes for homogeneous sensing of nucleic acids and imaging of fixed E. coli cells.

We have designed a second-generation TASC (target-assisted self-cleavage) probe. It is based on the switching-on of incorporated cis-acting DNAzyme activity upon the target-induced conformational change of the otherwise inactive off-target probes locked in an intrastrand base-paired hairpin geometry. With E. coli 16S ribosomal RNA-relevant oligonucleotides as targets, the locked TASC probe exhibits an allosteric factor of k(on)/k(off) = 65 and the sequence selectivity is high, in terms of single nucleotide difference, when particular sequence and length of targets are chosen. Preliminary experiments with fixed E. coli cells show that the locked TASC probe with a FRET pair can be used to image fixed E. coli cells.

Allosteric Regulation↗

PubMed2005

Highly sensitive genotyping using artificial riboregulator system.

Bacterial Proteins↗

PubMed2004

A facile route to dynamic glycopeptide libraries based on disulfide-linked sugar-peptide coupling.

We report here that disulfide-linked dynamic glycopeptide libraries can be constructed from 1-thiosugar and cysteine-rich oligopeptide building blocks upon gentle air oxidation of a slightly basic (pH 7.8) aqueous solution thereof. A mixture of 1-thiogalactose and two oligopeptides H2N-CysGlyCysGly-CO2H and H2N-GlyCycCysGlyGly-CO2H, for example, affords a poorly HPLC-resolved disulfide library composed of various sugar-peptide conjugates and cyclic peptides, at least 10 of which can be identified by ESI mass spectrometry. The building components of disulfide members are exchangeable with each other in the presence of dithiothreitol as an initiator to allow dynamic equilibration. A preliminary SPR examination shows that the thiogalactose-derived library indeed contains active divalent galactoside species capable of cross-linking peanut lectin molecules.

Combinatorial Chemistry Techniques↗