Hiroshi Sumitomo

Oligosaccharide-Carrying Styrene-Type Macromers. Polymerization and Specific Interactions Between the Polymers and Liver Cells

Abstract Polystyrene derivatives with lactose, glucose, maltose, maltotriose, maltopentaose, and maltoheptaose on each benzene ring were prepared by the radical polymerization of a new class of macromers synthesized by coupling the corresponding oligosaccharide lactones with p-vinylbenzylamine. These polymers consisting of amphiphilic structural units were water-soluble, and organic solutes were bound to hydrophobic microenvironments of the polymers in water. α-D-Glucopyranose-carrying polymers were recognized and precipitated by concanavalin A. Cultivation of liver cells (hepatocytes) was attempted using culture dishes whose surface was coated with lactose-, glucose-, maltose-, and maltotriose-carrying polystyrenes. It has been found that a lactose-carrying polystyrene (PVLA) is a useful surface material for hepatocyte culture. 1) Highly specific adhesion of hepatocytes was attained for PVLA-coated dishes with or without serum supplement. 2) The cell adhesion was a threshold phenomenon with respect to th...

Separation of Parenchymal Liver Cells Using a Lactose-Substituted Styrene Polymer Substratum

Earlier we reported that a lactose-carrying polystyrene (PVLA) was effective as a surface material for the adhesion of rat hepatocytes. Hepatocyte adhesion to PVLA-coated dishes reached 73% in 1 h and a maximum (92%) after 12 h in serum-supplemented Williams’ medium E. The hepatocyte adhesion was; (1) galactose-specific, (2) a threshold event, (3) effected by high galactose-density (cluster effect), (4) calciumion dependent, and (5) inhibited by colchicine. These characteristics are similar to those for the clearance of asialoglycoproteins by hepatocyte. It is known [4-10] that asialoglycoproteins, whose oligosaccharide terminals are galactopyranosyl residues, are taken up from the blood circulation by hepatocytes and degraded by lysosomes. Therefore, it is assumed that the hepatocyte adhesion is mediated by galactose-specific receptors of the surface of a hepatocyte. This paper reports that PVLA is useful for the separation of parenchymal cells from non-parenchymal cells. The isolation of parenchymal cells by the collagenase perfusion technique was introduced by Berry and Friend [11], developed by Seglen [12,13] and has been extensively used [14-17]. According to this method, parenchymal cells are sepa-

Preparation of a new polyamide macromer having a vinylbenzyl group from bicyclic oxalactam and its radical copolymerization with styrene

SummaryA new polyamide macromer having a vinylbenzyl end group (1), of which molecular weight was 3700–3800, was prepared by the anionic polymerization of bicyclic oxalactam (2) followed by the reaction with p-vinylbenzylamine. Its radical copolymerization with styrene was conducted to obtain a novel graft copolymer consisting of a polystyrene stock-chain and hydrophilic polyamide branches.

Water permeation and solute rejection behaviors of a novel hydrophilic polyamide membrane

SummaryThe poly(BOL) membrane prepared by “casting polymerization” exhibited an excellent fractional solute-rejection behavior in the aqueous solution, having a comparatively sharp boundary region at the molecular weight range of about 200 to 1400, together with an extremely high water permeability. These conspicuous behaviors, as well as a great capacity for water absorption, may result from some delicate arrangement of polar hydrophilic and nonpolar hydrophobic microdomains probably formed along and between the polymer chains.

Polyamides as barrier materials

In the performance data of various polyamide and related membranes published to date there should be valuable information for molecular design of more excellent barrier materials. But at present a means for their evaluation and optimization is still not clear. One of the reasons may at least come from the competitive flood of proposals for the detailed mechanisms of reverse osmosis, e.g. the solution-diffusion model, the sieve model, the preferential sorption model and so on.109)

Synthesis of a β-(1→6)-linked polysaccharide via ring-opening polymerization with neighboring-group participation

Abstract (1→6)-β- d -Galactopyranan was synthesized by cationic ring-opening polymerization of 1,6-anhydro-2- O -benzoyl-3,4-di- O -benzyl-β- d -galactopyranose and subsequent deprotection. The polymerization proceeded at 0° and 20°, using 10–50 mol% of phosphorus pentafluoride as initiator in dichloromethane, to give the polymer of M n 2.6–3.6 × 10 3 . The benzyl and benzoyl groups were removed by using sodium in liquid ammonia and an exclusively (1→6)-linked β- d -galactopyranan oligosaccharide of average d.p. 7 was obtained. The formation of the β-(1→6)-linkage was explained by a neighbouring-group effect on the steric control of the propagation step: BzO-2 in the growing terminal unit reacted with the cyclic tri-alkyloxonium ion to form a stable dioxacarbenium (dioxolenium) ion, which allowed exclusive β-side attack of the incoming monomer.

Ring-opening polymerization of bicyclic acetals, oxalactone, and oxalactam

Reaction mechanisms of ring-opening polymerization and structures and properties of resulting polymers of bicyclic acetals including 6,8-dioxabicyclo[3.2.1]octane (abbreviated to DBO) and 6,8-dioxabicyclo[3.2.1]oct-3-ene (DBOE), bicyclic oxalactone 6,8-dioxabicyclo[3.2.1]octan-7-one (DBOO), bicyclic oxalactam 8-oxa-6-azabicyclo[3.2.1.]octan-7-one (BOL), and related hetero bicyclic compounds are reviewed. Polysaccharide analogues were prepared from DBO and DBOE. Novel macrocyclic oligoesters were obtained in high yields from DBOO. BOL yielded easily a novel hygroscopic polyamide membrane of high molecular weight.

Peculiar transition observed on the temperature dependence of water permeability of a novel hydrophilic polyamide membrane

SummaryThe relationship between the logarithmic hydraulic permeability and the reciprocal absolute temperature for a novel hydrophilic polyamide membrane peculiarly refracted at about 27°C, which was inferred to be some kind of transition point of the poly(BOL) in water. Some participation mode of water molecules in polar sites, including inter- and intramolecular hydrogen bonds through amide and ether groups, along poly(BOL) chains may vary discontinuously at the temperature.

Interaction between rat hepatocytes and oligosaccharide-containing polystyrene derivatives.

オリゴ糖を側鎖にもつポリスチレン型単独重合体を塗布した培養皿の上でラット肝細胞の接着実験を行い, 重合体中の糖鎖が生物認識信号としての機能を発現することと, 重合体がハイブリッド型生医学材料としての優れた特性をもつことを明らかにした。グルコース, マルトース, ラクトース, 及びマルトトリオースから出発して重合体を合成し, その希薄溶液をガラス及びポリスチレン製培養皿に静重して重合体を吸着させることによって, 重合体を塗布した培養皿を調製した, ラクトースを側鎖にもつ重合体 (PVLA) は, 血清の有無にかがわらず, 肝細胞の接着能を飛躍的に向上させることと, この効果が10-4mg mlの臨界濃度以上の溶液を用いることによって特異的に発現することを見いだした. 肝細胞がPVLAのD-ガラクトース糖鎖末端を認識し, 結合することにより接着機能が発現するものと考えた.

Polymerization of bicyclic acetals

SummaryAn optically active, stereoregular polyacetal having a dextran-type backbone structure but opposite absolute configuration of the asymmetric carbons (the L-series) was prepared by the cationic ring-opening polymerization of (+)-(1R, 4R, 5S)-4-bromo-6,8-dioxabicyclo[3.2.1]octane (