Recently, separation technique of fine particles from suspension with membrane using overlapped driving forces of pressure field and electric field has been widely used in pharmaceutical industry, food industry, biological industry and so on.
Electrophoresis and electroosmosis are very important phenomena for electrodialysis, electro -ultrafiltration, electroosmotic dewatering of sludge, isoelectric focusing, etc. Therefore, the former-equations concerning electrophoresis and electrodialysis are discussed from a practically available point of view.
This paper deals with the following subjects.
(1) The effect of particle concentration of suspension on electrophoretic velocity is discussed. This problem is very important in the case where concentrative suspension is treated practically.
(2) Equation of electroosmotic flow rate passing through particle packed bed, respective membranes combined in series and in parallel with different kinds of membranes.
(3) Electrokinetic phenomena in the nonaqueous dispersion system and the applications of these phenomena to separation are introduced.
(4) The characteristics of electro-ultrafiltration and problems in electro-ultrafiltration to be solved are discussed.
(5) Recent studies on continuous separation of biochemical substances such as protein, enzyme, hormone, etc. are reviewed and in the cases of scale up and continuous operation for separation apparatus, problems to be solved hereafter are considered.

抄録全体を表示

After prolonged incubation of target cells with hormones or neurotransmitters, the cellular responses are often blunted, a phenomenon generally referred to desensitization. In rat parotid acinar cells, desensitization of substance P-induced inos itol 1, 4, 5-trisphosphate (IP₃) formation has been documented. Substance P stimulation does not, however, inducea loss of responsiveness to muscarinic cholinergic stimulation in these same cells. The desensitization of the substance P response occurs within 10 sec after the addition of the peptide and essentially completed by 1 min. Desensitization is generally divided into two categories : one form is the homologous desensitization, in which only agonists specific to the receptor act as the desensitizing agent. The other form is heterologous which is characterized by diminished responsiveness to agonist for different receptor pathways, which is linked to the same signalling pathway : The desensitization of the substances P-induced IP₃ response is parallelled by a lossof specific binding sites for substance P. Thus the homologous desensitization apparently involves down-regulation of the substance P receptor. The substance P receptors are coupled to GTP binding protein. However, the GTP binding protein may not be related to the desensitization, because the effect of GTP_γS was not desensitized in the permeabilized-cells which had been desensitized to substance P. The recovery of the binding sites as wellas the recovery of the responsiveness to substance P is slow, requiring 1-2h. As a kind of feedback system, the protein kinase C may inhibit Ca²⁺-mobilizing receptor systems. Phorbol esters, exclusiveactivators of protein kinase C, inhibited substance P-induced IP₃ formation. However, the loss of substance P receptors was not induced by the phorbol ester. Inhibitors of protein kinase C inhibited the effect of phorbol ester, but not the desensitization. These results suggest that the desensitization of substance P is not related to the protein kinase C-system.

抄録全体を表示

Polarized cells such as epithelial cells and polarized neurons are characterized by their cell surface organization in which proteins are segregated and maintained in distinct plasma membrane domains. In order to examine the continuity of lipid bilayer between different plasma membrane domains, a method has been introduced to fuse liposomes selectively to one domain of the cell surface using influenza hemagglutinin protein.
When liposomes containing fluorescent lipids were fused to the apical domain of epithelial Madin Darby canine kidney (MDCK) cells, diffusion of lipids to the basolateral surface was observed only when fluorescent lipids were distributed in the inner leaflet of the liposomes. On the other hand, when liposomes were fused to the axon of cultured hippocampal neurons, diffusion of neither inner nor outer leaflet lipids to the somatodendritic domain was observed. These results suggest that the epithelial cells and the neurons have different membrane barriers. In MDCK cells, newly synthesized plasma membrane proteins are segregated in trans Golgi network to be transported to either apical or basolateral domains. Recent data suggest the occurrence of subdomains enriched with apical proteins and glycosphingolipids in the Golgi apparatus.

抄録全体を表示

We have investigated the interactions of three classes of antimicrobial peptides (hypelcin A, trichopolyn I, and magainins) with lipid bilayers by using several physichochemical techniques (fluorescence, circular dichroism, infrared absorption, and differential scanning calorimetry) to obtain basic information on the molecular-level mechanisms for their bioactivities. In zwitterionic phosphatidyl-choline membranes, hydrophobic peptides, hypelcin A and trichopolyn I, form helices, deeply penetrating the hydrophobic region of the bilayers. There are no specific interactions between membranebound peptide molecules. The penetration disrupts the lipid packing, permeabilizing the bilayers. The membrane action of hypelcin A, the larger peptide, is three fold stronger. In contrast to these hydrophobic peptides, cationic magainin peptides specifically bind with acidic lipid bilayers, e.g., phosphatidylglycerol, to form amphiphilic helices. Electrostatic interactions are important in the binding process. The helical rods lie parallel to the membrane surface and form an aggregate. Magainins cause minimal perturbation of the hydrophobic core of the membranes, coinciding with much weaker membrane permeabilization activity. However, detailed permeabilization mechanisms are a subject of further study.

抄録全体を表示

Polyimide membranes of 6 FDA- p- PDA, 6 FDA-4, 4'-ODA and BTC-4, 4'-ODA were prepared. Gas permeabilities and selectivities of carbon dioxide and methane for the films were measured. 6 FDA polyimides exhibit both high selectivities and high permeabilities in CO₂/CH₄ separation. Molecular structure of polyimides were investigated by using molecular simulation technique. 6FDA polyimides show helix configuration due to bending and twisting of polymer chain at carbon atom having-C (CF₃) ₂- substituent groups. On the other hand normal polyimides without-C (CF₃) ₂- give straight configuration. Helix configuration can be one of the important reason for high selectivity and high permeability of hexafluoro-substituted polyimide.

抄録全体を表示

The release of drugs such as ketoprofen and indomethacin from polymer membrane of poly (2-methacryloyloxyethyl phosphorylcholine (MPC) -co-n-butyl methacrylate (BMA)) was investigated with attention to the unique characters of the copolymer as a hydrogel. The release rate of these drugs was increased with an increase in MPC content in the copolymer. The rate of hydration in poly (MPC-co-BMA) was increased with an increase not only in MPC composition and but also in temperature. Therefore, the release rate of drugs was reversibly regulated in response to the change in temperature. It can be concluded that the release of drugs from the MPC copolymer membrane was accelerated by the positive change of the hydration with an increase in temperature and was suppressed by the formation of skin layer at the surface of the membrane with a decrease in temperature.

抄録全体を表示