Showing papers by "Kyoto University published in 1989"

A thin slice preparation for patch clamp recordings from neurones of the mammalian central nervous system.

Abstract: (1) A preparation is described which allows patch clamp recordings to be made on mammalian central nervous system (CNS) neurones in situ. (2) A vibrating tissue slicer was used to cut thin slices in which individual neurones could be identified visually. Localized cleaning of cell somata with physiological saline freed the cell membrane, allowing the formation of a high resistance seal between the membrane and the patch pipette. (3) The various configurations of the patch clamp technique were used to demonstrate recording of membrane potential, whole cell currents and single channel currents from neurones and isolated patches. (4) The patch clamp technique was used to record from neurones filled with fluorescent dyes. Staining was achieved by filling cells during recording or by previous retrograde labelling. (5) Thin slice cleaning and patch clamp techniques were shown to be applicable to the spinal cord and almost any brain region and to various species. These techniques are also applicable to animals of a wide variety of postnatal ages, from newborn to adult.

Structural parts involved in activation and inactivation of the sodium channel.

Abstract: Structure-function relationships of the sodium channel expressed in Xenopus oocytes have been investigated by the combined use of site-directed mutagenesis and patch-clamp recording. This study provides evidence that the positive charges in segment S4 are involved in the voltage-sensing mechanism for activation of the channel and that the region between repeats III and IV is important for its inactivation.

Primary structure and expression from complementary DNA of skeletal muscle ryanodine receptor.

Abstract: The sequence of 5,037 amino acids composing the ryanodine receptor from rabbit skeletal muscle sarcoplasmic reticulum has been deduced by cloning and sequencing the complementary DNA The predicted structure suggests that the calcium release channel activity resides in the C-terminal region of the receptor molecule, whereas the remaining portion constitutes the 'foot' structure spanning the junctional gap between the sarcoplasmic reticulum and the transverse tubule

Primary structure and functional expression of the cardiac dihydropyridine-sensitive calcium channel

Abstract: IN cardiac muscle, where Ca2+ influx across the sarcolemma is essential for contraction, the dihydropyridine (DHP)-sensitive L-type calcium channel1 represents the major entry pathway of extracellular Ca2+. We have previously elucidated the primary structure of the rabbit skeletal muscle DHP receptor by cloning and sequencing the complementary DNA2. An expression plasmid carrying this cDNA, microinjected into cultured skeletal muscle cells from mice with muscular dysgenesis, has been shown to restore both excitation-contraction coupling and slow calcium current missing from these cells, so that a dual role for the DHP receptor in skeletal muscle transverse tubules is suggested3. We report here the complete amino-acid sequence of the rabbit cardiac DHP receptor, deduced from the cDNA sequence. We also show that messenger RNA derived from the cardiac DHP receptor cDNA is sufficient to direct the formation of a functional DHP-sensitive calcium channel in Xenopus oocytes. Furthermore, higher calcium-channel activity is observed when mRNA specific for the polypeptide of relative molecular mass ∼140,000 (α2-subunit)4–6 associated with the skeletal muscle DHP receptor is co-injected.

Manufacturer-supplier relationships in Japan and the concept of relation-specific skill☆

Abstract: This paper investigates manufacturer-supplier relationships in Japan based on field research on two major industries. I first show that various modes of relations exist and that longstanding relations are more densely distributed where customized parts are transacted. Then I show that this phenomenon can be ascribed to ratings exercised by the purchasing firm on some skill accumulated by each supplier. I construct the concept of multidimensional relation-specific skill accumulated by each supplier through learning and technological investments, and relate this concept to Aoki's work on relational quasi-rent and Williamson's scheme to classify transactions.

Ascorbate Peroxidase in Tea Leaves: Occurrence of Two Isozymes and the Differences in Their Enzymatic and Molecular Properties

Abstract: Two isozymes of ascorbate (AsA) peroxidase were found in tea leaves, and one of them (AsA peroxidase II) was purified to homogeneity, as judged by polyacrylamide gel electrophoresis. AsA peroxidase II is a monomer with a molecular weight of 34,000 and contains protoheme, but it is not a glycoprotein. The enzyme showed a Soret peak at 409 nm and at 420 nm when oxidized and reduced, respectively, with an a-band at 556 nm. The oxidized enzyme showed two small peaks at 478 nm and 530 nm

Primary structure and functional expression from complementary DNA of the rod photoreceptor cyclic GMP-gated channel

Abstract: The complete amino-acid sequence of the cyclic GMP-gated channel from bovine retinal rod photo-receptors, deduced by cloning and sequencing its complementary DNA, shows that the protein contains several putative transmembrane segments, followed by a region that is similar to the cyclic GMP-binding domains of cyclic GMP-dependent protein kinase. Expression of the complementary DNA produces cyclic GMP-gated channel activity in Xenopus oocytes.

ATL‐derived factor (ADF), an IL‐2 receptor/Tac inducer homologous to thioredoxin; possible involvement of dithiol‐reduction in the IL‐2 receptor induction.

Abstract: HTLV-I transformed T cells not only express a large number of interleukin-2 receptors [IL-2R/p55(Tac)], but also produce a factor named ATL-derived factor (ADF) that augments the expression of IL-2R/p55(Tac). Based on a partial N-terminal amino acid sequence, complementary DNA (cDNA) clones for human and mouse ADF were isolated and sequenced. Recombinant ADF produced by COS-7 monkey kidney cells showed IL-2R/Tac inducing activity on YT cells, which are sensitive for ADF. ADF mRNA was strongly expressed in HTLV-I(+) T cells lines, but not in inactivated cells (THP-1, unstimulated PBMC). Furthermore, in normal human peripheral blood mononuclear cells, the expression of ADF mRNA was enhanced by mitogens or phorbol myristate acetate, suggesting a possible involvement of ADF in the lymphocyte activation. Homology analysis revealed an unexpected relationship between ADF and dithiol-reducing enzyme, thioredoxin, involved in many important biological reactions such as the conversion of ribonucleotides into deoxyribonucleotides, or the stabilization of glucocorticoid receptors. The biological significance of the generation of a redox potential in lymphocyte activation, and the possible involvement of dithiol reduction in the induction of IL-2R/Tac are discussed.

Conformal Field Theory on Universal Family of Stable Curves with Gauge Symmetries

Abstract: Publisher Summary This chapter focuses on the conformal field theory (CFT) on universal family of stable curves with gauge symmetries. CFT has not only useful application to string theory and two-dimensional critical phenomena but also has beautiful and rich mathematical structure, and it has interested many mathematicians. CFT is characterized by infinite-dimensional symmetry such as Virasoro algebra. Especially, its correlation functions are characterized by differential equations arising from representations of infinite-dimensional Lie algebras. Physically, correlation functions should have the properties such as locality, holomorphic factorization, and monodromy invariance (duality). To build conformal field theory having such properties, usual approach is to construct holomorphic (chiral) conformal blocks, which are the half of the theory and to study its monodromy.

Transmembrane control of cadherin-mediated cell adhesion: a 94 kDa protein functionally associated with a specific region of the cytoplasmic domain of E-cadherin.

Abstract: Cadherins are a family of transmembrane glycoproteins which play a key role in Ca(2+)-dependent cell-cell adhesion. Cytoplasmic domains of these molecules are anchored to the cell cytoskeleton and are required for cadherin function. To elucidate how the function of cadherins is controlled through their cytoplasmic domains, we deleted five different regions in the cytoplasmic domain of E-cadherin. After transfecting L cells with cDNA encoding the mutant polypeptides, we assayed aggregating activity of these transfectants; all these mutant proteins were shown to have an extracellular domain with normal Ca(2+)-sensitivity and molecular weight. Two mutant polypeptides with deletions in the carboxy half of the cytoplasmic domain, however, did not promote cell-cell adhesion and had also lost the ability to bind to the cytoskeleton, whereas the mutant molecules with deletions of other regions retained the ability to promote cell adhesion and to anchor to the cytoskeleton. Thus, the cytoplasmic domain contains a subdomain which was involved in the cell adhesion and cytoskeleton-binding functions. When E-cadherin in F9 cells or in L cells transfected with wild-type or functional mutant cadherin polypeptides was solubilized with nonionic detergents and immunoprecipitated, two additional 94 and 102 kDa components were coprecipitated. The 94 kDa component, however, was not detected in the immunoprecipitates from cells expressing the mutant cadherins which had lost the adhesive function. These results suggest that the interaction of the carboxy half of the cytoplasmic domain with the 94 kDa component regulates the cell binding function of the extracellular domain of E-cadherin.

Electrokinetic chromatography: An interface between electrophoresis and chromatography

Abstract: Electrokinetic chromatography is a new type of analytical separation method, which utilizes the experimental technique of capillary zone electrophoresis in combination with the principle of chromatography. A theoretical plate number of 250 000 is easily obtained in 10 min.

Antioxidant activity of β-carotene-related carotenoids in solution

Abstract: The effect of the antioxidant activity of β-carotene and related carotenoids on the free radical-oxidation of methyl linoleate in solution was examined by measuring the production of methyl linoleate hydroperoxides. Canthaxanthin and astaxanthin which possess oxo groups at the 4 and 4′-positions in the β-inonone ring retarded the hydroperoxide formation more efficiently than β-carotene and zeaxanthin which possess no oxo groups. The rates of autocatalytic oxidation of canthaxanthin and astaxanthin were also slower than those of β-carotene and zeaxanthin. These results suggest that canthaxanthin and astaxanthin are more effective antioxidants than β-carotene by stabilizing the trapped radicals.

Positron emission tomography using fluorine-18 deoxyglucose in evaluation of coronary artery bypass grafting

Abstract: To assess the clinical value of positron emission tomography (PET) in the evaluation of coronary artery bypass grafting (CABG), PET perfusion and metabolic imaging using nitrogen-13 ammonia and fluorine-18 deoxyglucose (FDG) was performed before and 5 to 7 weeks after CABG in 22 patients with coronary artery disease. Postoperative improvement in hypoperfusion was observed more often in the metabolically active segments (62%) than in the inactive segments (27%) on the preoperative PET study (p less than 0.05). Similarly, the postoperative lessening of wall motion abnormality was observed more often in the metabolically active segments (78%) than in the inactive segments (22%) (p less than 0.001). Of 19 asynergic segments showing increased FDG uptake before operation, the postoperative PET revealed a decrease in FDG uptake in 13 (68%) and persistent uptake in 6 (32%). The improvement in asynergy was observed in all the segments that showed a postoperative decrease in FDG uptake, but in only 50% of those with persistent uptake (p less than 0.01). On the other hand, 4 of 5 segments showing a new FDG uptake after operation revealed further wall motion abnormality. Furthermore, the segments metabolically active before operation were more likely to have patent grafts (95%) than the metabolically inactive segments (70%) (p less than 0.05). Thus, preoperative metabolic imaging using PET appears to be useful for predicting the response to CABG. Improvement in metabolic derangement was associated with improvement in regional function after CABG.

Tissue biocompatibility of cellulose and its derivatives.

Abstract: Tissue biocompatibility of cellulose and its derivatives was examined in two in vivo tests, one for absorbance by living tissue and one for foreign body reaction. The samples examined were regenerated celluloses and cellulose derivatives: methyl cellulose, ethyl cellulose, aminoethyl cellulose, hydroxyethyl cellulose, and cellulosic polyion complexes. The in vivo absorbance by living tissue was found to depend on the degree of crystallinity and the chemical structure of the sample. The foreign body reaction was relatively mild for all the samples examined, showing that cellulose can be converted to biocompatible materials by physical and/or chemical transformation.

Reconstitution of Tubular Myelin from Synthetic Lipids and Proteins Associated with Pig Pulmonary Surfactant

Abstract: To analyze the mechanism of formation of tubular myelin (TM), we reconstituted TM from synthetic lipids and two surfactant-associated proteins (SP15 and SP35). SP15 was extracted from lyophilized pig pulmonary surfactant with 5% Triton X-100 and purified by DEAE-cellulose, CM-cellulose, and affinity chromatography with a specific antibody. SP35 was extracted from the precipitate of the 5% Triton X-100 extraction with pH 10 borate buffer and purified by DEAE-cellulose column chromatography. Lipid-SP15 complex was formed by a detergent dialysis method using octylglucopyranoside, and to this complex were added various concentrations of SP35 at 37° C. Structures similar to TM were formed when lipid-SP15 complex containing dipalmitoylphosphatidylcholine:phosphatidylglycerol from egg lecithin (2:1) and SP15 (lipid/protein, 5:1) was incubated with SP35 at concentrations of 0.15 to 0.22 mg/ml in CaCl2-containing buffer. At higher concentrations of SP35, many six-sided lattices were formed; the addition of EDTA ab...

Differential regulation of three sodium channel messenger RNAs in the rat central nervous system during development

Abstract: The levels of the mRNAs encoding sodium channels I, II and III in various regions of the developing rat central nervous system (from embryonal day 10 to postnatal day 90) have been examined by blot hybridization analysis with specific probes. The three sodium channel mRNAs exhibit different temporal and regional expression patterns. The expression of sodium channel I mRNA rises after a lag phase to adult levels during the second and third postnatal weeks with stronger increases in caudal regions of the brain and in spinal cord. Sodium channel II mRNA increases steadily until the first postnatal week, keeping high adult levels in rostral regions of the brain or reaching low adult levels after the second postnatal week in most caudal regions of the brain and in spinal cord; cerebellum shows low levels during the first two postnatal weeks but high adult levels. In all regions, sodium channel III mRNA attains maximum levels around birth and decreases during the first and second postnatal weeks to reach variable low adult levels. These results suggest that sodium channel III is expressed predominantly at fetal and early postnatal stages and sodium channel I predominantly at late postnatal stages, whereas sodium channel II is expressed throughout the developmental stages studied with greater regional variability.

Dynamics and stability in coordination of multiple robotic mechanisms

Abstract: This paper discusses the dynamical coordination of multiple robot manipulators or a multifingered robot hand. The coor dination problem is divided into two phases: determining the resultant force by multiple robotic mechanisms; determining the internal force between mechanisms. The resultant force is used for maintaining dynamic equilibrium and for generat ing the restoring force. A dynamic coordinative control scheme which guarantees the object stability is proposed, associated with the determination of the resultant forces. The internal force is used to satisfy the static frictional constraints and is related to contact stability. The minimizing internal force is defined as the internal force which yields the minimal norm force satisfying static frictional constraints and the minimizing internal force is solved by applying a nonlinear programming method. The concept of the minimizing inter nal force is fundamental and important because it can theo retically answer whether the object can be grasped and m...

Exogenous expression of mouse interferon gamma cDNA in mouse neuroblastoma C1300 cells results in reduced tumorigenicity by augmented anti-tumor immunity

Abstract: To examine the influence of interferon gamma (IFN-gamma) on tumorigenicity, we established constitutively IFN-gamma-producing cell lines from a malignant mouse neuroblastoma, C1300, by retroviral transfer of a mouse IFN-gamma cDNA. The gene-transferred cells generally showed an enhanced high-level expression of the major histocompatibility complex class I antigens at the cell surface and the transcription levels, irrespective of their IFN-gamma-producing potential. Although in vitro cell growth of these cells was unaffected by the IFN-gamma production, their s.c. tumor growth in syngeneic A/J mice was dependent upon levels of IFN-gamma production; tumors induced by a low-producer line grew well at a rate similar to those induced by the parental one, but tumor growth of a high-producer line was strongly suppressed. This apparent tumor suppression was abolished by simultaneous i.p. injection of anti-Lyt2.2 and/or anti-IFN-gamma monoclonal antibodies, and subsequently large tumors of the high producer were generated. Anti-asialoganglioside GM1 antibodies allowed the high-producer line to induce a substantial but only transient tumor growth, whereas other antibodies, such as anti-Lyt2.1, anti-IFN-beta, and anti-activated macrophage, had no such effect. The mice immunized with the high-producer line were resistant to tumor growth of the parental cells but permitted another kind of A/J tumor line, Sa-1, to induce remarkable tumors. These results indicate that the reduced tumorigenicity of the IFN-gamma high-producer line was due to the augmented specific anti-tumor immunity, in which cytotoxic T lymphocytes seemed to play a decisive role, probably as a result of the immunomodulatory effects of the IFN-gamma derived from the tumor.

Fractal Dimension of Fault Systems in Japan: Fractal Structure in Rock Fracture Geometry at Various Scales

Abstract: Based on fault maps, whether or not the fracture geometry of rocks is self-similar, was examined by using a box-counting algorithm. The statistical self-similarity (fractal structure) of the fault fracture systems holds well at the scale of about 2 to 20 km. The fractal dimension in Japan varied from 1.05 to 1.60. The fractal dimension is about 1.5–1.6 at the central part of the Japan Arc, and decreases with distance from the center. At a smaller scale, the fractal structure also holds well in the rock fracture geometry. The fractal dimension of the North Izu Peninsula fault system (branching faults) is 1.49 at the scale of 0.625 to 10 km, the fractal dimension of rock fracture geometry at the scale order of 10−1 to 10−2 meters is about 1.49–1.61. The upper limit of the fractal dimension of rock fracture geometry is about 1.6, judging from the estimation of fractal dimension on actual fracture geometry of rocks. This value may impose a restraint on modeling of faulting and the fracture process of rocks.

Magnetism in La2CuO4 based compounds

Abstract: To explain recent observations of incommensurate spin modulation in doped La2CuO4 an interacting electron system is investigated from the itinerant side where a magnetic band is nearly half-filling. An analytical solution of spin density wave with infinite higher harmonics is obtained, giving rise to a soliton lattice spin structure, striped charge domain walls which run perpendicular to the modulation vector Q and associated midgap state. Temperature and doping dependences of Q are predicted.

A harmonic calculus on the Sierpinski spaces

Abstract: A reconstruction of the well-known theory of calculus on [0, 1] will naturally bring a calculus associated with the harmonic functions, Laplace operator, Gauss-Green’s formula and so on, on theN-Sierpinski space whose Hausdorff dimension is (logN)/(log 2).