Publications by authors named "Koichi Shigeno"

The purpose of our research is to develop functional additives that enhance mucosal absorption of biologics, such as peptide/protein and antibody drugs, to provide their non-to-poor invasive dosage forms self-managed by patients. Our previous in vivo and in vitro studies demonstrated that the intranasal absorption of biologics in mice was significantly improved when coadministered with oligoarginines anchored chemically to hyaluronic acid via a glycine spacer, presumably through syndecan-4-mediated macropinocytosis under activation by oligoarginines. The present mouse experiments first revealed that diglycine-L-tetraarginine-linked hyaluronic acid significantly enhanced the intranasal absorption of sulpiride, which is a poor-absorptive organic compound with a low molecular weight.

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Article Synopsis
  • Previous research showed that L-octaarginine linked to hyaluronic acid can improve the absorption of protein drugs under 22 kDa when taken intranasally.
  • This study explored its use for larger antibody drugs, showing that the bioavailability of ranibizumab (48 kDa) increased from 0.67% to 6.2% when combined with the hyaluronic acid derivative.
  • Results indicated that this absorption enhancement mechanism relies on syndecan-4-induced macropinocytosis, making it effective for various antibody sizes, with no involvement from clathrin or caveolin-1 in the uptake process.
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Article Synopsis
  • - The study investigates how cell-penetrating peptides attached to polymers can enhance the absorption of biologics through mucosal routes, highlighting past mouse experiments that showed significant improvements in mucosal absorption of protein drugs using hyaluronic acid modified with l-octaarginine.
  • - Results revealed that somatropin had a bioavailability of 19% when applied to lung mucosa but only about 1% with nasal administration, which increased to 46% when paired with the absorption enhancer.
  • - The effectiveness of the absorption enhancer varied by route; while oral and rectal administration saw improved somatropin absorption, intragastric use did not yield positive results, suggesting the pulmonary route is optimal for administering biologics.
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Low-temperature co-fired ceramics (LTCCs) are dielectric materials that can be co-fired with Ag or Cu; however, conventional LTCC materials are mostly poorly thermally conductive, which is problematic and requires improvement. We focused on ZnAlO (gahnite) as a base material. With its high thermal conductivity (~59 W·m·K reported for 0.

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Cell-penetrating peptides such as oligoarginines are one of promising tools that improve mucosal absorption of poorly membrane-permeable biologics. We have already demonstrated that conjugation of L-octaarginine to hyaluronic acid via a tetraglycine spacer resulted in a 3-fold enhancement of nasal absorption of somatropin (Mw: ca. 22.

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We have developed an aggregate of D-octaarginine immobilized at multiple points on a co-polymer of N-vinylacetamide and acrylic acid. Previous studies revealed that immunoglobulin G and A were induced when mice were inoculated with influenza virus antigens under coadministration with the D-octaarginine-immobilized polymers as a mucosal vaccine adjuvant. Infection experiments demonstrated that mice vaccinated with a mixture of inactivated influenza viruses and the polymers were protected from infection with mouse-adapted infectious viruses.

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We have been investigating the potential use of polymers modified with cell-penetrating peptides as an adjuvant for mucosal vaccination and have already developed nondegradable poly( N-vinylacetamide- co-acrylic acid) (PNVA- co-AA) with which d-octaarginine, a typical cell-penetrating peptide, was grafted. Our previous murine infection experiments demonstrated that immunoglobulin G (IgG) and immunoglobulin A (IgA) were induced in systemic circulation and secreted on nasal mucosa, respectively, through 4-time nasal inoculations with a mixture of influenza viral antigens and d-octaarginine-linked PNVA- co-AA at 7-day intervals, and that immunized mice were perfectly protected from homologous virus infection. In the present study, we designed novel biodegradable polymers bearing cell-penetrating peptides from a perspective of clinical application.

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Peptide and protein drugs, which are categorized as biologics, exhibit poor membrane permeability. This pharmacokinetic disadvantage has largely restricted the development of noninvasive dosage forms of biologics that deliver into systemic circulation. We have been investigating the potential use of cell-penetrating peptide-linked polymers as a novel absorption enhancer to overcome this challenge.

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We have been investigating the potential of oligoarginine-linked polymers as an adjuvant for mucosal vaccination that induces immunoglobulin G (IgG) in systemic circulation and immunoglobulin A (IgA) secreted on the mucosa. Our latest infection experiments demonstrated that mice immunized nasally with a mixture of inactivated influenza viruses and poly(N-vinylacetamide-co-acrylic acid) (PNVA-co-AA) modified with D-octaarginine were perfectly protected from homologous virus infection. On the contrary, virus infection was observed in mice immunized with the antigen alone.

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