Jieon Kim

The limited intestinal absorption via paracellular pathway is responsible for the low oral bioavailability of doxorubicin.

Abstract 1. Doxorubicin exhibited dose-independent pharmacokinetics after intravenous (5–20u2009mg/kg) and oral (20–100u2009mg/kg) administration to rats. Nearly all (82.1–99.7%) of the orally administered doxorubicin remained unabsorbed, and the hepatic first-pass extraction ratio and oral bioavailability of doxorubicin were approximately 0.5% and 1%, respectively. Based on these results, it is likely that the primary factor responsible for the low oral bioavailability of doxorubicin is the limited intestinal absorption, rather than the CYP3A4-mediated first-pass metabolism. 2. Moreover, the in vitro transport and cellular uptake studies using Caco-2 cell monolayers have revealed that doxorubicin crosses the intestinal epithelium primarily via the paracellular pathway (accounting for 85.6% of the overall absorptive transport) probably due to its physicochemical properties (hydrophilic cation; pKau2009=u20099.67, logu2009Pu2009=u2009−0.5). These results suggest that P-glycoprotein (P-gp)-mediated efflux activity does not play a significant role in limiting the intestinal absorption of doxorubicin, attenuating the absorptive transport by only 5.56–13.2%. 3. Taken together, the present study demonstrated that the limited and paracellular intestinal absorption of doxorubicin was a major factor responsible for its low oral bioavailability, restricting the role of CYP3A4-mediated first-pass metabolism and P-gp-mediated efflux.

The effect of pore formers on the controlled release of cefadroxil from a polyurethane matrix.

The effect of various pore formers on the controlled release of an antibacterial agent from a polymeric device was examined in order to develop a novel biomaterial that prevents bacterial adhesion and growth on its surface. Cefadroxil was chosen as the model antibiotic and was incorporated into a polyurethane matrix by the solvent-casting method. Polyethylene glycol (PEG) 1450, D-mannitol, or bovine serum albumin (BSA) was used as a pore former. The amount of cefadroxil released from various formulations at 37 degrees C was measured by HPLC. The morphological change of matrices before and after release studies was investigated by scanning electron microscopy (SEM). The duration of antimicrobial activities of matrices against Escherichia coli and Bacillus subtilis was evaluated by measuring the diameters of the inhibition zone. Changing the weight fraction and particle size of the pore formers/drug mixtures could control the release of cefadroxil from the matrix. The release rate of cefadroxil increased as the loading dose of the pore former increased (15<20<25%). Cefadroxil released from these devices exhibited antibacterial activity for 5-6 days. These results imply that an antibiotic-loaded polymeric device that could prevent bacterial infection on its surface can be formulated using appropriate pore formers.

On generating sets of Yoshikawa moves for marked graph diagrams of surface-links

A marked graph diagram is a link diagram possibly with marked

IDEAL COSET INVARIANTS FOR SURFACE-LINKS IN ℝ4

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On the Alexander biquandles of oriented surface-links via marked graph diagrams

-valent vertices. S. J. Lomonaco, Jr. and K. Yoshikawa introduced a method of representing surface-links by marked graph diagrams. Specially, K. Yoshikawa gave local moves on marked graph diagrams, nowadays called Yoshikawa moves. It is now known that two marked graph diagrams representing equivalent surface-links are related by a finite sequence of these Yoshikawa moves. In this paper, we provide some generating sets of Yoshikawa moves on marked graph diagrams representing unoriented surface-links, and also oriented surface-links. We also discuss independence of certain Yoshikawa moves from the other moves.

Computations of quandle cocycle invariants of surface-links using marked graph diagrams

In [Towards invariants of surfaces in 4-space via classical link invariants, Trans. Amer. Math. Soc.361 (2009) 237–265], Lee defined a polynomial [[D]] for marked graph diagrams D of surface-links in 4-space by using a state-sum model involving a given classical link invariant. In this paper, we deal with some obstructions to obtain an invariant for surface-links represented by marked graph diagrams D by using the polynomial [[D]] and introduce an ideal coset invariant for surface-links, which is defined to be the coset of the polynomial [[D]] in a quotient ring of a certain polynomial ring modulo some ideal and represented by a unique normal form, i.e. a unique representative for the coset of [[D]] that can be calculated from [[D]] with the help of a Grobner basis package on computer.

Biquasile colorings of oriented surface-links

Carrell defined the fundamental biquandle of an oriented surface-link by a presentation obtained from its broken surface diagram, which is an invariant up to isomorphism of the fundamental biquandle. Ashihara gave a method to calculate the fundamental biquandle of an oriented surface-link from its marked graph diagram (ch-diagram). In this paper, we discuss the fundamental Alexander biquandles of oriented surface-links via marked graph diagrams, derived computable invariants and their applications to detect non-invertible oriented surface-links.

A multiple conjugation biquandle and handlebody-links

By using the cohomology theory of quandles, quandle cocycle invariants and shadow quandle cocycle invariants are defined for oriented links and surface-links via broken surface diagrams. By using symmetric quandles, symmetric quandle cocycle invariants are also defined for unoriented links and surface-links via broken surface diagrams. A marked graph diagram is a link diagram possibly with

Biquandle (co)homology and handlebody-links

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Presentation of immersed surface-links by marked graph diagrams

-valent vertices equipped with markers. S. J. Lomonaco, Jr. and K. Yoshikawa introduced a method of describing surface-links by using marked graph diagrams. In this paper, we give interpretations of these quandle cocycle invariants in terms of marked graph diagrams, and introduce a method of computing them from marked graph diagrams.