出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.34, no.6, pp.294-303, 2009 (Released:2015-06-14)

All living organisms on the earth rely solely on a single molecule as an energy currency, ATP (adenosine triphosphate). This small molecule supports nearly all the activities that require energy, and our body synthesizes roughly as much ATP every day as our body weight. In the biological world, ATP synthesis is certainly the most prevalent chemical reaction and the enzyme, ATP synthase, responsible for most of this task, is one of the most ubiquitous, abundant proteins on the earth. ATP synthase uses physical rotation of its own subunits as a step of catalysis - a novel mechanism, different from any other known enzymes. Rotation is not a favourite motion in living organisms; there is no animal with wheels, no bird with a propeller, and no fish with a screw. The crystal structures of the main part of ATP synthase show in atomic detail how the appearance of this world tiniest motor made of protein is remarkably reminiscent of the man–made motors. The driving force that spins ATP synthase is trans-membrane gradient of hydrogen ion concentration that is generated by respiration (burning the food) or by sunshine. We have videoimaged the rotary motion of ATP synthase that spins as fast as several hundred revolutions per second. The mechanism of the motor is completely different from the man–made motor. ATP synthase is bi–particle structure with a common rotary shaft. The flow of hydrogen ions through the lower particle drives the rotation of the central rotor that then forces upper particle to make the bending motion for synthesis of ATP. Imagine billions of billion rotary motors are spinning in our body, day and night, without rest. When the motors stop, we die.
著者
林 久由 鈴木 裕一
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.36, no.6, pp.293-299, 2011 (Released:2012-05-18)
参考文献数
38

Chloride ions play many physiological roles, including regulation of cell volume, fluid secretion and acid.base balance. An efficient absorption of Cl- in the intestine is important to maintain the optimal levels of Cl- in the body. Three chloride absorptive pathways have been proposed : 1) a paracellular pathway, which is dependent on potential difference; 2) an electroneutral pathway involving parallel functioning of Na+/H+ exchange and Cl-/HCO3- exchange; 3) an HCO3- dependent Cl- absorptive pathway, which is not coupled to a parallel Na+/H+ exchange. Among these chloride absorptive mechanisms, the second electroneutral NaCl absorption is thought to be a predominant pathway. At least six Cl-/HCO3- exchangers (SLC4A1, SLC4A2, SLC4A3, SLC26A2, SLC26A3, SLC26A6) have been found in intestinal epithelial cells. However, the role of each exchanger and regulatory mechanisms in the intestine have not been well studied. This review in particular focuses on the role and regulation of SLC26A3 in the gastrointestinal tract.
著者
松﨑 勝巳
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.32, no.4, pp.185-189, 2007 (Released:2015-06-27)

The conversion of soluble, nontoxic amyloid β-protein (Aβ) to aggregated, toxic Aβ rich in β-sheet structures by seeded polymerization is considered to be the key step in the development of Alzheimer’s disease. Accumulating evidence suggests that lipid rafts (microdomains) in membranes mainly composed of sphingolipids (gangliosides and sphingomyelin) and cholesterol play a pivotal role in this process. Our model membrane studies revealed the following mechanism. Soluble Aβ with unordered structures specifically binds to raft-like membranes containing a ganglioside cluster, the formation of which is facilitated by cholesterol. The membrane-bound Aβ forms an α-helix-rich structure at lower densities. At higher densities, Aβ undergoes a conformational transition to a β-sheet-rich structure that can serve as a seed for amyloid fibril formation. This model was confirmed in cellar level using rat pheochromocytoma PC12 cells. Fourier-transform infrared spectroscopic and electron micrographic studies revealed that the structures of Aβ fibrils formed in solution and lipid rafts are different. The fibrilization can be inhibited by small organic compounds and biocompatible nanogels.
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.34, no.6, pp.328-335, 2009 (Released:2015-06-14)
被引用文献数
1 1

It was previously considered that the practical application of liposomal medicines was very difficult. The pharmaceutical technologies for mass production, long term stability during storage, encapsulation efficiency of the drug, etc. were seemed big problems to be solved, and it was well known that the liposomal particles are apt to be entrapped in vivo by the reticuloendothelial system (RES) such as liver, spleen, etc. Fortunately, owing to the progress of science, about 10 liposomal medicines containing the anticancer agents, the antifungal agents, etc. were launched out and are now contributed to medical treatment in the world. Recently liposomes are expected to be useful as the vectors for in vivo nucleic acid (plasmid DNA, siRNA, etc.) therapy and as the tools for target validation in the area of drug discovery. There are already many liposomal reagents for transfection, and some clinical trials are performed using liposomes. It is considered that liposomes, the membrane–structure particles, have unlimited potential in the medical field.
著者
須郷 高信 斎藤 恭一
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.13, no.5, pp.272-282, 1988-09-01 (Released:2011-03-04)
参考文献数
72
被引用文献数
5 2

Many methods of recovery of uranium from seawater have been suggested : coprecipitation, adsorption, ion flotation, solvent extraction, and others. Of these, only the adsorption method using a suitable solid adsorbent seems to be feasible with regard to economic and envirom ental impacts. Extensive investigations of adsorbents have been carried out. Among the various organic resins, chelating resins containing amidoxime groups have been selected. A novel amidoxime-group-containing adsorbent of hollow-fiber form was prepared by radiation-induced graft polymerization of acrylonitrile onto a polyethylene hollow fiber, followed by chemical conversion of the produced cyano group to an amidoxime group. The fixed-bed adsorption column, 30 cm in length and charged with the bundle of amidoxime hollow-fibers, was found to adsorb uranium from seawater at a sufficiently high rate : 0.66 mg uranium per g of adsorbent in 25 days.
著者
長井 孝紀 田中 滋康 高田 真理
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.29, no.3, pp.154-160, 2004-05-01 (Released:2011-03-04)
参考文献数
20

Amphibians regulate the osmotic and ionic composition of their body fluids by water and ion transport across their skin. When dehydrated, desert toads press down the pelvic region of ventral skin on moist surfaces to achieve maximal water absorption. Aquaporins (AQP) are trans-membrane proteins permeable to water. We cloned three isoforms of AQP (AQP-h1, -h2, -h3) in tissues of tree frogs. AQP-h3 was abundantly expressed in the pelvic region of ventral skin, facilitating water absorption across the skin. Antibodies to AQP-h3 labeled the cell membrane of the granulosum cells in the skin. AQP-h3 was progressively expressed during metamorphosis of larval frogs. Expression of AQP-h3 was facilitated by and diuretic hormone, argine vasotocin. Collectively, AQP-h3 is a molecule to play a positive role in water absorption across the amphibian skin. In bullfrogs short circuit current across the skin was suppressed by amiloride, a blocker for epithelial Na+ channel (ENaC), showing that transport of sodium ions occurs through ENaC. Na+ transport increased in parallel with metamorphosis of the tadpole. In cultured skins of the tadpole Na+ transport was facilitated by aldosterone, but counteracted by prolactin. Such counteraction seemed to be removed by thyroid hormone (T3) during metamorphosis to adapt a terrestrial environment.
著者
高野 幹久 湯元 良子
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.36, no.4, pp.145-153, 2011 (Released:2011-12-13)
参考文献数
25
被引用文献数
3 3

The lung is expected as a promising administration route for protein and peptide drugs. However, information concerning alveolar absorption mechanisms of these high molecular weight drugs is lacking. The alveolar region of the lung is lined with a continuous epithelium comprising of type I and type II epithelial cells, and squamous type I cells cover 90~95% and cuboidal type II cells cover 5~10% of the alveolar surface area. Using primary cultured alveolar type II and transdifferentiated type I cells, however, it was found that type II cells would play a significant role in albumin and insulin endocytosis from the alveolar space. Functional and siRNA studies suggest that albumin is taken up by clathrin-mediated endocytosis in type II cells, while clathrin- and caveolae-independent but dynamin-dependent pathway is involved in insulin endocytosis. The approach to enhance insulin uptake by the alveolar epithelial cells and absorption from the lung is also discussed.
著者
小松 裕明
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.21, no.5, pp.311-317, 1996-09-01 (Released:2011-03-04)
参考文献数
23

It was now well established that phosphatidylcholines or phosphatidylglycerols can form an interdigitated structural phase (Iphase), in which acyl chains of the lipids fully interpenetrate the hydrocarbon chains of the opposing monolayer in the presence of short chain alcohols and some other amphiphiles. It has been suggested that the interdigitated structure as well as a hexagonal II structure plays an important role in regulating many functions of biological membranes. We have demonstrated the participation ofIphase formation in ethanol-induced liposomal aggregation and fusion. We have also focused on control of permeability as one of the biomembrane functions, and the effects of ethanol on the permeability of large unilamellar vesicles composed of various phospho-lipids were studied by monitoring the leakage of the fluorescent dye, calcein, entrapped in the inner aqueous phase of the vesicles. In the cases of mixed membranes composed of DPPC and dilauroyl phosphatidylethanolamine (DLPE), as well as DPPC liposomal membranes, large permeabilities were observed in the wide range of ethanol concentrations, where the normal bilayer andIphase coexist and the membrane is in a phase-separated state. These results suggested that ethanol can disturb the normal control of biological membrane permeability.
著者
酒井 清孝
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.14, no.1, pp.31-44, 1989-01-01 (Released:2011-03-04)
参考文献数
24

Various materials are presently available for hollow fiber dialysis membranes which satisfy technical and medical requirements such as high permeability to uremic toxins and water, biocompatibility, resistance to sterilization, and high mechanical strength. New dialysis membranes with high permeability to β2-microglobulin and with biocompatibility leading to low complement activation have been developed for more optimal hemodialysis. Data on structure and permeability are then required to prepare the new dialysis membranes. Much attention should be paid also to the geometry of hollow fiber dialysis membranes available for chronic renal failure patients with elevated hematocrits caused by the administration of erythropoietin.
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.33, no.3, pp.94-101, 2008 (Released:2015-06-18)

Serotonin transporter (SERT), a member of Na+/Cl– - dependent transporter family, is predicted to be a protein with a twelve membrane-spanning structure, which terminates the serotonergic neural transmission by re-uptaking serotonin into pre-synapse. It has been well-known that SERT is a target of antidepressants and abusive drugs. Although the pathogenesis of depression and mechanism underlying antidepressants action remains unclear, recent accumulated evidences have revealed that antidepressants promote the regeneration of neurons, which was damaged by repeated stress and recurrences of depression. In addition, analysis of crystal structure of bacterial leucine transporter, a homologue of mammalian Na+/Cl– - dependent neurotransmitter transporter, provides us a new information concerning the interactions of tricyclic antidepressants with serotonin transporter.
著者
伊藤 新次 吉岡 薫 寺川 美加
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.29, no.1, pp.58-65, 2004-01-01 (Released:2011-03-04)
参考文献数
11

In the ultrafiltration of honey, filtration efficiency can not be expressed by permeate flux because it is necessary to dilute raw honey with water. Instead, rate of recovered sugar (RRS) which considers permeate flux and sugar content, was employed as an indicator of the filtration efficiency in this study.The effect of dilution on filtration efficiency was that RRS increased with a decrease in sugar content at initial stage of filtration. However, at concentration factor (CF) above 1.5, RRS at sugar content of 40% was higher than that at sugar content of 30%. This result was probably caused by changes in characteristics of suspended solids in raw honey due to dilution. In this case, the changes were small when the sugar content was 50%.The effect of operation temperature on filtration efficiency was shown that high RRS was observed at 50°C rather than 20°C and 30°C, however, temperature influenced cake resistance less than sugar content during filtration.The effects of operation pressure and cross-flow velocity on filtration efficiency were that when cross-flow velocity was 1.07-1.6 m/s, RRS increased as pressure increased. Whereas influence of cross-flow velocity on RRS decreased as pressure became decreased.Furthermore, total operation energy was easily calculated using inlet pressure under several filtration conditions to obtain a constant volume of permeate.At constant pressure, the cross-flow velocity was proportional to the energy. At constant cross-flow velocity, there were optimum pressures at each cross-flow velocity for useful filtration.
著者
髙田 礼人
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.31, no.5, pp.243-247, 2006 (Released:2015-06-19)

Enveloped viruses have a lipid bilayer (envelope) surrounding viral components including their genomic DNA or RNA. The entry of these viruses into host cells requires membrane fusion between viral envelope and host cell plasma membrane. Envelope-associated glycoproteins bind to the specific receptors and catalyze membrane fusion. Newly synthesized viral proteins and genomic nucleic acids are incorporated into new envelope at the final stage of virus replication, budding. This article reviews the interaction between viral proteins and host cell membrane.
著者
上山 洋一郎
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.34, no.6, pp.351-354, 2015 (Released:2015-06-14)

Silver ions, while being lethal to single-celled microorganisms, are known to be harmless to human cells. We have adopted highly active fine organic silver grains, developed by combining our long accumulated fine organic synthesis and fine particle technologies, to the filter. Antibodies (also known as immunoglobulin) are used by the immune system to identify and neutralize foreign objects, such as viruses. For the antiviral function, we have applied the specific antibody ‘immunoglobulin yolk (IgY)’ for the filter, and the filter has proved to dramatically reduce the infectivity of type A (H1N1, H3N2) and type B influenza viruses and also of the Avian flu A(H5N1).
著者
吉岡 朋久
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.30, no.1, pp.29-37, 2005 (Released:2015-07-01)
被引用文献数
1 1
著者
水本 隆雄
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.33, no.2, pp.82-84, 2008 (Released:2015-06-17)
参考文献数
4
被引用文献数
7 6

Harnal D is a fast-disintegrating tablet containing fine, modified-release (MR) particles. The dissolution-controlled film on the MR particles consisted of a mixture of water-soluble and -insoluble polymers, with a very smooth particle surface (as determined by SEM observation). During dissolution testing, very fine pores on the surface of the MR particles were formed, and the drug release rate was controlled through these pores. The dissolution-controlled film was usually damaged during the compression process, and thus the dissolution rate increased. However WOWTAB technology, which was applied to Harnal D, can be manufactured at a low compression pressure, thereby avoiding damage to the dissolution-controlled film. In fact, there was no difference in the dissolution rate between the MR particles and tablet.
著者
喜多 英敏
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.33, no.5, pp.247-253, 2008 (Released:2015-06-14)
被引用文献数
1

This paperreviews the recent research and development of gas separation membranes. Gas separation propertiesbased on the relationship with the structure–property ofpolymeric materials are summarized and recent advances innew materials attemptingto create a molecular sieving property in order to improve the membrane performance aredescribed.
著者
田中 一宏 酒多 喜久
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.36, no.3, pp.113-121, 2011 (Released:2012-09-14)
参考文献数
48
被引用文献数
2

The recent research circumstances of photocatalytic overall splitting of H2O and the membrane separation of H2 and O2 for constructing the hydrogen production system by applying photocatalytic H2O splitting are introduced. Here, the principle of photocatalytic H2O splitting and photocatalysts for the reaction are explained on the historical aspect. Furthermore, the photocatalysts with high photocatalytic ability to the reaction, not only the photocatalysts and photocatalytic systems work under solar irradiation but also those show high efficiency are introduced. Incorporating gas separation membranes into the photocatalytic reactor leads to a safe and energy-efficient hydrogen production process. Since any research of application of gas separation membrane to this purpose has not been found in the literature, our research is introduced. The goal performance that the membrane should achieve to produce safe H2 and O2 streams have been determined by a simple model of a membrane module. Permeability and selectivity of H2 over O2 for silica membranes, carbon membranes, and polyimide membranes have been examined in a temperature range from 35 to 100 °C. Some silica membranes have passed the goal at 100 °C for a wet mixture of H2/O2(2/1).
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.31, no.4, pp.221-223, 2006 (Released:2015-07-01)
著者
大場 哲彦 渡名喜 力 大木 和夫
出版者
日本膜学会
雑誌
(ISSN:03851036)
巻号頁・発行日
vol.29, no.3, pp.169-179, 2004-05-01 (Released:2011-03-04)
参考文献数
22
被引用文献数
1 1

Laurdan, one of the environment-sensitive fluorescent probes, is useful for monitoring membrane fluidity and is widely used for spectroscopic and imaging applications. In the imaging applications, the generalized polarization parameter (GP), defined by two fluorescent intensities at characteristic wavelengths, is used as a measure of membrane fluidity and polarity. However, time-resolved fluorescent spectra of laurdan revealed that the three excited states concern with the emission spectra. We have measured the steady-state fluorescence spectra and the fluorescence anisotropy of laurdan, prodan and NBD-PE in the DPPC and DLPC bilayers at various temperatures. The spectral dependence on the excitation wavelength is interpreted as the red edge effects that are related to the existence of excited-state distribution of fluorophores on their interaction energy with the environment and the slow dielectric relaxation of this environment. The emission peak of laurdan in the liquid-crystalline phase is independent of the red edge excitation, while prodan and NBD-PE show significant red edge effects. This results strongly suggest that laurdan changes its electronic excited state by the specific interaction with a few water molecules in the bilayers and that in addition the non-specific solvent relaxation causes further spectral shifts in the case of prodan in the bilayers and laurdan in the micella. A new three state model for the absorption and emission of laurdan is proposed. The availability and limitation of the GP method are disscussed.