Eisaku Iizuka

Effects of polyelectrolyte complex (PEC) on human periodontal ligament fibroblast (HPLF) function. II. Enhancement of HPLF differentiation and aggregation on PEC by L-ascorbic acid and dexamethasone.

In addition to many types of extra cellular matrix (ECM) in vivo, cells are stimulated by many types of vitamins, hormones, growth factors, etc. In this paper the effects of L-ascorbic acid 2-phosphate (Asc-2P) and dexamethasone (Dex) on proliferation and differentiation of human periodontal ligament fibroblast (HPLF) using polyelectrolyte complex (PEC) as a matrix in vitro will be discussed. The PEC was composed of chitosan as a polycation, with carboxymethyl (CPEC) or sulfated chitin (SPEC). Asc-2P (0.2 mM) inhibited the growth of HPLF on CPEC, but promoted the growth on SPEC. Moreover, the aggregation of HPLF on CPEC was inhibited by Asc-2P, but that on SPEC was induced in the presence of Asc-2P and Dex. Although Asc-2P reduced an increase in alkaline phosphatase (ALPase) activity of HPLF on CPEC as well, it induced a twofold increase in ALPase activities on SPEC and TCD. Furthermore, in the medium containing Asc-2P and 100 mM of Dex, cell growth was inhibited, but ALPase activity was promoted on both SPEC and TCD to form many aggregates on SPEC. ALPase activity increased by twofold over that of HPLF cultured in the medium containing only Asc-2P. Therefore, it is suggested that the cell functions of HPLF are controlled by the combination of PEC and additives.

Electric orientation of liquid crystals of poly-γ-benzyl-l-glutamate

Abstract The orientation of liquid crystals of poly-γ-benzyl- l -glutamate in low-strength electric fields was studied mainly by the infrared dichroic ratio. 1. 1. A high degree of orientation of liquid crystals of poly-γ-benzyl- l -glutamate in electric fields resulted from the cooperative but very complicated behavior of the polypeptide molecules. 2. 2. In dilute liquid-crystalline solutions, the polypeptide molecules behaved as if independent molecular clusters having a dipole moment some 730 times as large as that of the single polypeptide molecule (of degree of polymerization 650) were present in solution. 3. 3. The polypeptide molecules in liquid-crystalline solution could not achieve perfect orientation owing to the nature of the liquid crystals even if only the birefringent phase existed in solution. 4. 4. Electric current through liquid-crystalline solution was slight, and did not seem to have much effect on the electric orientation.

Light Scattering by Liquid Crystals of Poly-γ-benzylglutamates in Electric Field

Abstract -Liquid crystalline solutions of poly-γ-benzylglutamates have been measured in static electric fields using light scattering methods. It has been made clear that molecular clusters are present in solution when high dielectric solvents are used. Sufficient conditions, though not the necessary ones, have been obtained to indicate that the molecular clusters are rod-like in a very low electric field supporting an idea previously proposed. From the change of the V h scattering mode, polymer (and molecular cluster) orientation can be determined. Change in the scattering mode when the direction of the external electric field is reversed is drastic, and a tentative explanation for this is given. In dioxane, formation of the rod-like molecular clusters and their orientation are brought about by the induced dipole of the polymer and/or the electric current through the liquid crystalline solution unlike that in the high dielectric solvents.

Experiments on Magnetic Orientation of Liquid Crystals of Poly-γ-Benzyl-L-Glutamate

Orientation of poly-γ-benzyl-L-glutamate under magnetic field has been measured in liquid-crystalline solution and in film, cast and dried from the solution, by means of optical and electrostatic methods. The orientation which is in the direction of the external field is of an antiparallel type and proposed to be due to induced magnetic dipoles of the side chain groups of the polypeptide molecules. Although the orientation is poor in solution, it is striking in film, and some cooperative behavior of the permanent electric dipoles in a system of the molecular clusters of the polypeptide and of the solvent molecules, which becomes especially prominent as the solution is dried up, is suggested to be involved. Some wall effects from the surfaces of the optical cell used, however, make it difficult of detect true magnetic orientation in solution.

Effects of polyelectrolyte complex (PEC) on human periodontal ligament fibroblast (HPLF) function. I. Three-dimensional structure of HPLF cultured on PEC

Human periodontal ligament fibroblast (HPLF) cultured on tissue culture dishes (TCD), irrespective of the presence of serum, showed only a spreading form. In contrast, using polyelectrolyte complex (PEC) as a matrix, HPLF showed spreading, round, and aggregate forms. Cells of the inner part of the aggregate contacted with each other to form a three-dimensional structure, and this condition corresponded to typical tissues in vivo. These seemed to be related to the interrelation between growth and morphology; that is, the HPLF of the spreading form was considered to belong to a proliferation phase, and the HPLF of the round and aggregate forms, with a little growth, seemed to belong to a functional phase of the cell cycle, indicating that PEC is able to control such cell functions as proliferation, morphology, and differentiation. The cell aggregate was observed only on PEC with carboxymethyl residues and was stained by alizarin red (AR), which suggested mineralization. The spreading cells on PEC containing sulfate residues were not stained by AR. Therefore, it was found that there was a certain relationship between cell growth and morphology, and that PEC affected the cell cycle and promoted proliferation and differentiation of HPLF.

Magnetic-Field Orientation of the Liquid Crystals of Polyribonucleotide Complexes

Abstract Small-angle laser light scattering and double refractive index measurements on the nematic solutions of poly(A) poly(U) and poly(A)-2poly(U) have been carried out in static magnetic fields and the data have been discussed in terms of alignment of rodlike molecular clusters having induced, magnetic dipole moments. It has been suggested that these polyribonucleotide complexes are diamagnetic and their maximum magnetic susceptibilities are in the direction parallel to the axes of polymer helices. Best agreement with the measurements is obtained assuming that certain wall effects of the optical cell and spacer, which is introduced into the optical cell, are involved.

Interaction of polyelectrolytes with albumin using fluorescence measurement

Abstract Because proteins are polyampholytes, they can interact with poly-electrolytes, mainly through an electrostatic force. In this report we discuss the interaction of serum albumin, which is a major component of serum proteins, with synthetic polyelectrolytes using fluorescent measurement. Polycations interact with anionic amino acids in a relatively random fashion only above the isoelectric point of albumin. On the other hand, polyanions interact selectively with a specific site of albumin, the drug binding site II in which basic amino acids are localized.

NMR Measurements of Liquid Crystals of Poly-γ-Benzyl-L-Glutamate in Static Electric Fields

A couple of parallel-plate electrodes have been made of Nesa glass. NMR spectra of liquid-crystalline solutions of poly-γ-benzyl-L-glutamate in static electric fields obtained using these electrodes are reliable. The signal of a solvent molecule such as dichloromethane or dibromomethane splits into a doublet owing to magnetic dipole-dipole interactions as in the case of the magnetic orientation of these solutions, indicating that the solvent molecules orient in the direction of the electric field. Dilute liquid-crystalline solutions which still do not contain isotropic portions evidently have a strong center signal showing presence of free solvent molecules. Orientation of the solvent molecules is apt to be disturbed by a weak electric current through the solution and magnitude of the steady-state separation of the doublet can not be used as a measure for the polymer (and molecular cluster) orientation.

Species specificity of the conformation of silk fibroin in solution

Abstract The conformation of silk fibroins in aqueous solution is determined by optical rotatory dispersion and infrared absorption. 1. 1. Silk fibroins of subfamilies Bombycinae and Thaumetopoeinae, whose main primary structures are alternating glycine and alanine (or serine in the former sequences), essentially exist in a disordered conformation. 2. 2. Bombycinae fibroins are slightly β when taken straight from the posterior silkgland and Thaumetopoeinae fibroin is slightly α-helical in a certain species. 3. 3. Saturniinae fibroins, whose main primary structures are sequences of consecutive alanines, contain 15–20% α-helix. 4. 4. In all the fibroins tested, however, a cross β-form appears, regardless of the subfamily, when more than 30% (v/v) dioxane or methanol is added to solution. The α-helix which is primarily present in Saturniinae fibroins remains unchanged while in Thaumetopoeinae fibroins it is newly formed.

Circular dichroism of poly(β-benzyl-l-aspartate) films in the α, β and ω conformations

The conformations of poly(β-benzyl l-aspartate) (PBLA) in film were studied by means of circular dichroism (c.d.). Films of PBLA show c.d. which is related to the benzyl chromophores of this polypeptide. The magnitude and sign of the c.d. of the benzyl chromophores depend on the conformation i.e. α-helix, ω-helix or β-form. The aromatic c.d. of the left-handed α-helix or the left-handed ω-helix is negative in sign, and that of the β-form is positive in sign. The absolute magnitude of the c.d. of PBLA is much larger in the ω-helical conformation than in the α-helical or the β-conformations. In the left-handed α-helical PBLA (α-PBLA), the positive dichroism band of the n−π∗ peptide electronic transition is observed at about 226 nm. When the α-PBLA is converted to the left-handed ω-helical PBLA (ω-PBLA), the band at 226 nm shifts to 224 nm, and its magnitude becomes much smaller. In the β-form PBLA (β-PBLA), this band is negative in sign and observed at 223 nm. The absolute magnitude of the c.d. relative to this electronic transition follows the order: β-form < ω-helix < α-helix.