Search results for: Kumiko Sakai-Kato

Items from 1 to 20 out of 35 results

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Detailed Morphological Characterization of Nanocrystalline Active Ingredients in Solid Oral Dosage Forms Using Atomic Force Microscopy

Kumiko Sakai-Kato, Kunie Nanjo, Yuki Takechi-Haraya, Yukihiro Goda, more

AAPS PharmSciTech > 2019 > 20 > 2 > 1-8

The characterization of nanocrystalline active ingredients in multicomponent formulations for the design and manufacture of products with increased bioavailability is often challenging. The purpose of this study is to develop an atomic force microscopy (AFM) imaging method for the detailed morphological characterization of nanocrystalline active ingredients in multicomponent oral formulations. The...

article

Imaging and size measurement of nanoparticles in aqueous medium by use of atomic force microscopy

Yuki Takechi-Haraya, Yukihiro Goda, Kumiko Sakai-Kato

Analytical and Bioanalytical Chemistry > 2018 > 410 > 5 > 1525-1531

Size control of nanoparticles in nanotechnology-based drug products is crucial for their successful development, since the in vivo pharmacokinetics of nanoparticles are size-dependent. In this study, we evaluated the use of atomic force microscopy (AFM) for imaging and size measurement of nanoparticles in aqueous medium. The height sizes of rigid polystyrene nanoparticles and soft liposomes were measured...

article

Involvement of scavenger receptor class B type 1 and low-density lipoprotein receptor in the internalization of liposomes into HepG2 cells

Kumiko Sakai-Kato, Mari Sakurai, Yuki Takechi-Haraya, Kunie Nanjo, more

Biochimica et Biophysica Acta (BBA) - Biomembranes > 2017 > 1859 > 11 > 2253-2258

In this study, HepG2 cells, an in vitro model system for human hepatocytes, were used to evaluate the interaction of lipoprotein receptors with liposomes carrying fluorescently labeled cholesterol and their subsequent intracellular uptake. In these experiments, two lipoprotein receptors, scavenger receptor class B type 1 (SR-B1) and low-density lipoprotein receptor (LDLR), accounted for approximately...

article

Membrane Rigidity Determined by Atomic Force Microscopy Is a Parameter of the Permeability of Liposomal Membranes to the Hydrophilic Compound Calcein

Yuki Takechi-Haraya, Kumiko Sakai-Kato, Yukihiro Goda

AAPS PharmSciTech > 2017 > 18 > 5 > 1887-1893

We determined the permeability coefficient of a model hydrophilic drug, calcein, encapsulated within saturated lipid-based nano-sized liposomes of various lipid profiles. We demonstrated that the addition of cholesterol to liposomes containing saturated lipids increased the permeability of the liposomal membrane to calcein via a decrease in the membrane bending modulus, as determined by means of atomic...

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Enthalpy-driven interactions with sulfated glycosaminoglycans promote cell membrane penetration of arginine peptides

Yuki Takechi-Haraya, Ryo Nadai, Hitoshi Kimura, Kazuchika Nishitsuji, more

Biochimica et Biophysica Acta (BBA) - Biomembranes > 2016 > 1858 > 6 > 1339-1349

The first step of cell membrane penetration of arginine peptides is thought to occur via electrostatic interactions between positive charges of arginine residues and negative charges of sulfated glycosaminoglycans (GAGs) on the cell surface. However, the molecular interaction of arginine peptides with GAG still remains unclear. Here, we compared the interactions of several arginine peptides of Tat,...

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General considerations regarding the in vitro and in vivo properties of block copolymer micelle products and their evaluation

Kumiko Sakai-Kato, Nobuhiro Nishiyama, Masato Kozaki, Takeshi Nakanishi, more

Journal of Controlled Release > 2015 > 210 > C > 76-83

Block copolymer micelles are nanoparticles formed from block copolymers that comprise a hydrophilic polymer such as poly(ethylene glycol) and a poorly soluble polymer such as poly(amino acids). The design of block copolymer micelles is intended to regulate the in vivo pharmacokinetics, stability, and distribution profiles of an entrapped or block copolymer-linked active substance. Several block copolymer...

article

Physicochemical properties and in vitro intestinal permeability properties and intestinal cell toxicity of silica particles, performed in simulated gastrointestinal fluids

Kumiko Sakai-Kato, Masayuki Hidaka, Keita Un, Toru Kawanishi, more

BBA - General Subjects > 2014 > 1840 > 3 > 1171-1180

Amorphous silica particles with the primary dimensions of a few tens of nm, have been widely applied as additives in various fields including medicine and food. Especially, they have been widely applied in powders for making tablets and to coat tablets. However, their behavior and biological effects in the gastrointestinal tracts associated with oral administration remains unknown.Amorphous silica...

article

Elucidating the molecular mechanism for the intracellular trafficking and fate of block copolymer micelles and their components

Kumiko Sakai-Kato, Keita Un, Kunie Nanjo, Nobuhiro Nishiyama, more

Biomaterials > 2014 > 35 > 5 > 1347-1358

Block copolymer micelles have shown promise for the intracellular delivery of chemotherapeutic agents, proteins, and nucleic acids. Understanding the mechanism of their intracellular trafficking and fate, including the extracellular efflux of the polymers, will help improve their efficacy and minimize their safety risks. In this Leading Opinion paper, we discuss the molecular mechanism of block copolymer...

article

Intracellular trafficking mechanism, from intracellular uptake to extracellular efflux, for phospholipid/cholesterol liposomes

Keita Un, Kumiko Sakai-Kato, Yuki Oshima, Toru Kawanishi, more

Biomaterials > 2012 > 33 > 32 > 8131-8141

Liposomes are widely used as drug delivery vehicles to transfer chemotherapeutic agents, proteins, and nucleic acids into target cells. To improve therapeutic effects and reduce unexpected toxic side-effects, it is necessary to understand the mechanism of liposomal uptake into cells, and the intracellular fate of internalized liposomes. The intracellular fate of synthesized components used in the...

article

Evaluation of intracellular trafficking and clearance from HeLa cells of doxorubicin-bound block copolymers

Kumiko Sakai-Kato, Keiko Ishikura, Yuki Oshima, Minoru Tada, more

International Journal of Pharmaceutics > 2012 > 423 > 2 > 401-409

New technologies are needed to deliver medicines safely and effectively. Polymeric nanoparticulate carriers are one such technology under investigation. We examined the intracellular trafficking of doxorubicin-bound block copolymers quantitatively and by imaging doxorubicin-derived fluorescence using confocal microscopy. The polymers were internalized by endocytosis and distributed in endosomal/lysosomal...

article

Size separation and size determination of liposomes

Kumiko Sakai‐Kato, Shigenori Ota, Kenji Hyodo, Hiroshi Ishihara, more

Journal of Separation Science > 34 > 20 > 2861 - 2865

We developed a method for separating liposomes by size and determining their average diameters. Liposomes with different average diameters were separated on a monolithic silica capillary column, and the size of the liposomes corresponding to each peak was determined online with a dynamic light scattering detector coupled to the capillary liquid chromatography system. The calculated diameters for the...

article

Size separation of colloidally dispersed nanoparticles using a monolithic capillary column

Kumiko Sakai-Kato, Shigenori Ota, Toyohide Takeuchi, Toru Kawanishi

Journal of Chromatography A > 2011 > 1218 > 32 > 5520-5526

We developed a method to separate colloidally dispersed nanoparticles on monolithic capillary columns. Silica nanoparticles were eluted according to their sizes, and the plots of the logarithm of the size of nanoparticles against their elution volume showed good linearity (r=0.992) over wide range of sizes. Because of the high porosity of the monolithic column (porosity; 88%), the column's length...

article

Analysis of intracellular doxorubicin and its metabolites by ultra-high-performance liquid chromatography

Kumiko Sakai-Kato, Eiko Saito, Keiko Ishikura, Toru Kawanishi

Journal of Chromatography B > 2010 > 878 > 19 > 1466-1470

Doxorubicin, a highly effective anticancer drug, produces severe side effect such as cardiotoxicity, which is mainly caused by its metabolite, doxorubicinol. While in vitro studies by measuring cellular concentration of doxorubicin have been reported, there have been no reports on measuring cellular concentration of the metabolites. In this report, we developed a sensitive and high-throughput method...

article

Stability of folding structure of Zic zinc finger proteins

Kumiko Sakai-Kato, Yoshinori Umezawa, Katsuhiko Mikoshiba, Jun Aruga, more

Biochemical and Biophysical Research Communications > 2009 > 384 > 3 > 362-365

Zic family proteins have five C ₂ H ₂ -type zinc finger (ZF) motifs. We physicochemically characterized the folding properties of Zic ZFs. Alteration of chelation with zinc ions and of hydrophobic interactions changed circular dichroism spectra, suggesting that they caused structural changes. The motifs were heat stable, but electrostatic interactions had little effect on structural...

article

Screening system for d-Asp-containing proteins using d-aspartyl endopeptidase and two-dimensional gel electrophoresis

Kumiko Sakai-Kato, Tadatoshi Kinouchi, Noriko Fujii, Kazuhiro Imai, more

Amino Acids > 2009 > 36 > 1 > 125-129

d-Asp-containing proteins have been implicated in many aging-related diseases. To clarify the role of d-Asp-containing proteins in such diseases, we developed a screening system for these proteins using a d-aspartyl endopeptidase that specifically cleaves the proteins at the C-terminus. The digested proteins were detected by means of two-dimensional gel electrophoresis and identified using nano-liquid...

article

Structural requirements for the flavonoid fisetin in inhibiting fibril formation of amyloid β protein

Tatsuhiro Akaishi, Takeo Morimoto, Mami Shibao, Sayaka Watanabe, more

Neuroscience Letters > 2008 > 444 > 3 > 280-285

Fisetin (3,3′,4′,7-tetrahydroxyflavone) has been found to be neuroprotective, induce neuronal differentiation, enhance memory, and inhibit the aggregation of the amyloid β protein (Aβ) that may cause the progressive neuronal loss in Alzheimer's disease. The diverse collection of biological activities of this compound may lead to a new type of therapeutic drug for Alzheimer's disease. As the first...

article

CD spectra show the relational style between Zic-, Gli-, Glis-zinc finger protein and DNA

Kumiko Sakai-Kato, Akira Ishiguro, Katsuhiko Mikoshiba, Jun Aruga, more

BBA - Proteins and Proteomics > 2008 > 1784 > 7-8 > 1011-1019

Zic family proteins have five C2H2-type zinc finger motifs. The Zic-zinc finger domains show high homology to the corresponding domains of the Gli and Glis families, which also contain five C2H2-type zinc finger motifs. The zinc finger motifs of the proteins of these three protein families form an α-helix conformation in solution. The addition of oligo DNA that included a Gli-binding sequence increased...

article

Racemization of the amyloidal β Asp1 residue blocks the acceleration of fibril formation caused by racemization of the Asp23 residue

Kumiko Sakai-Kato, Megumi Naito, Naoko Utsunomiya-Tate

Biochemical and Biophysical Research Communications > 2007 > 364 > 3 > 464-469

Amyloid β proteins extracted from the amyloid cores of neuritic plaques are considerably racemized at their Asp residues. To assess the impact of d-Asp on amyloid β _1–42 conformation and on initiation of amyloid fibril formation, we used wild-type amyloid β _1–42 and analogs in which d-Asp was substituted for l-Asp at residues 1, 7, 23, and all combinations of these residues. Amyloid...

article

Cationic starch derivatives as dynamic coating additives for protein analysis in capillary electrophoresis

Kumiko Sakai-Kato, Masaru Kato, Tohru Nakajima, Toshimasa Toyo’oka, more

Journal of Chromatography A > 2006 > 1111 > 2 > 127-132

Positively charged starch derivatives were used to modify the inner surface of fused-silica capillaries by addition to running buffer, which were subsequently employed in capillary electrophoresis (CE). Capillaries coated with the cationic starch derivatives were shown to generate a stable, reversed electroosmotic flow (EOF) in the investigated pH range of 3–9. The presented coating procedure was...

article

Simultaneous analysis of cationic, anionic, and neutral compounds using monolithic CEC columns

Masaru Kato, Yuko Onda, Kumiko Sakai-Kato, Toshimasa Toyo’oka

Analytical and Bioanalytical Chemistry > 2006 > 386 > 3 > 572-577

A new capillary electrochromatography (CEC) column for the simultaneous analysis of cationic, neutral, and anionic compounds using CEC-ESI-MS is described. Three different silica monolith columns were prepared by changing the poly(ethylene glycol) (PEG) contents for comparison of the separation property of these columns. Different separation programs were used for the simultaneous separation of different...

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INFONA - science communication portal

Search results for: Kumiko Sakai-Kato

Detailed Morphological Characterization of Nanocrystalline Active Ingredients in Solid Oral Dosage Forms Using Atomic Force Microscopy

Imaging and size measurement of nanoparticles in aqueous medium by use of atomic force microscopy

Involvement of scavenger receptor class B type 1 and low-density lipoprotein receptor in the internalization of liposomes into HepG2 cells

Membrane Rigidity Determined by Atomic Force Microscopy Is a Parameter of the Permeability of Liposomal Membranes to the Hydrophilic Compound Calcein

Enthalpy-driven interactions with sulfated glycosaminoglycans promote cell membrane penetration of arginine peptides

General considerations regarding the in vitro and in vivo properties of block copolymer micelle products and their evaluation

Physicochemical properties and in vitro intestinal permeability properties and intestinal cell toxicity of silica particles, performed in simulated gastrointestinal fluids

Elucidating the molecular mechanism for the intracellular trafficking and fate of block copolymer micelles and their components

Intracellular trafficking mechanism, from intracellular uptake to extracellular efflux, for phospholipid/cholesterol liposomes

Evaluation of intracellular trafficking and clearance from HeLa cells of doxorubicin-bound block copolymers

Size separation and size determination of liposomes

Size separation of colloidally dispersed nanoparticles using a monolithic capillary column

Analysis of intracellular doxorubicin and its metabolites by ultra-high-performance liquid chromatography

Stability of folding structure of Zic zinc finger proteins

Screening system for d-Asp-containing proteins using d-aspartyl endopeptidase and two-dimensional gel electrophoresis

Structural requirements for the flavonoid fisetin in inhibiting fibril formation of amyloid β protein

CD spectra show the relational style between Zic-, Gli-, Glis-zinc finger protein and DNA

Racemization of the amyloidal β Asp1 residue blocks the acceleration of fibril formation caused by racemization of the Asp23 residue

Cationic starch derivatives as dynamic coating additives for protein analysis in capillary electrophoresis

Simultaneous analysis of cationic, anionic, and neutral compounds using monolithic CEC columns

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