Showing papers by "Hokkaido University published in 1979"

Membrane potential of mitochondria measured with an electrode sensitive to tetraphenyl phosphonium and relationship between proton electrochemical potential and phosphorylation potential in steady state.

Abstract: The membrane potential of mitochondria was estimated from the accumulation of tetraphenyl phosphonium (TPP+), which was determined with the TPP+-selective electrode developed in the present study. The preparation and some operational parameters of the electrode were described. The kinetics for uptake by mitochondria of TPP+ and DDA+ (dibenzyldimethyl ammonium) were analyzed, and it was found that TPP+ permeated the mitochondrial membrane about 15 times faster than DDA+. The final amounts of accumulation of TPP+ and DDA+ by mitochondria were approximately equal. For the state-4 mitochondria, the membrane potential was about 180 mV (interior negative). Simultaneous measurements of TPP+-uptake and oxygen consumption showed that the transition between states 3 and 4 was detectable by use of the TPP+-electrode. After the TPP+-electrode showed that state-4 was reached, the extra-mitochondrial phosphorylation potential was measured. The difference in pH across the membrane was measured from the distribution of permeant anion, acetate, so as to calculate the proton electrochemical potential. The ratio of extra-mitochondrial phosphorylation potential to proton electro-chemical potential, n was close to 3. This value of n was also found to be 3 when ATP was hydrolyzed under the condition that the respiratory chain was arrested. The implication that n = 3 was discussed.

HEAT‐INDUCED GELATION OF MYOSIN: FACTORS OF pH AND SALT CONCENTRATIONS

Abstract: The heat-induced gelation of myosin was optimally developed at temperatures between 60° and 70°C and at pH 6.0 as studied quantitatively by measuring shear modulus of myosin in 0.6M KCl. No difference was observed in the gelation profile, when KCl was replaced by NaCl. The shear modulus of the gel formed at 65°C and pH 6.0 increased proportionally to the 1.8 power of myosin concentration. Although the heat gelling ability of myosin as measured by the shear modulus did not increase with increasing salt concentration from 0.4–1.0M, irrespective of storage time at 0°C of the stock myosin solution (0.6M KCl) or suspension (0.1M KCl), it varied drastically with time of storage at salt concentrations between 0.1 and 0.3. This variation in shear modulus at O.1–0.3M KCl was apparent due to the storage conditions. These changes in the salt concentration dependence of the heat gelation of myosin corresponded well with the changes in solubility of myosin during storage. Studies on selected physico-chemical properties of the original stock myosin during storage indicated gradual increase in viscosity with little inactivation of ATPase as well as very slight decrease in sulfhydryl content, suggesting the spontaneous transformation (aggregation) of myosin molecules to a less soluble state.

Changes in shear modulus, ultrastructure and spin-spin relaxation times of water associated with heat-induced gelation of myosin

Abstract: Gelation of myosin in 0.6M KC1 at pH 7.0 and 6.0 during heating at various temperatures between 25–70°C was quantitatively measured by a simple shear modulus tester devised in our laboratory. Shear modulus data indicated that gelation occurs with a stepwise elevation of temperature from 30–60°C. Heat-treatment of the protein solution remarkably influenced the structure and water mobility in the system. Myosin gel formed by heating had a micro-network structure, which was not-present in the original myosin solution. The myosin gel had a slower value of spin-spin relaxation time compared to that of the original untreated sample, suggesting that the water mobility in the gel system was somehow restricted. The heat-induced gelation of myosin may be the result of the development of a three dimensional network structure which holds water in a less mobilized state.

Studies on Chitin. I. Acetylation of Chitin

Abstract: Chitin was converted into diacetylchitin and also into various kinds of acetylchitins. A fully acetylated chitin was prepared by the acetylation of chitin in acetic anhydride—methanesulfonic acid mixture at 0°C overnight, or in acetic anhydride—perchloric acid mixture at 0°C for 3 h. Variously acetylated chitins were prepared by similar procedures applying a calculated amount of acetic anhydride in glacial acetic acid. The reaction of alkaline chitin with acetic anhydride gave 0.3 acetylchitin (0.3 mol of –OH groups are acetylated per one N-acetylglucosamine residue), and heating this with anhydrous sodium acetate in acetic anhydride produced ca 1.1 acetylchitin. However, it was difficult to further improve the degree of acetylation by this alkaline method. The acetylation of chitin resulted in an increase of solubility in formic acid, and diacetylchitin was easily soluble even in 85-% aqueous formic acid. The analytical data showed that the chitin residue exists as a stable hemihydrate unless it is completely acetylated. Infrared absorption spectra for chitin and acetylchitins were also investigated.

Accumulation of Early Mitotic Cells in Ethidium Bromide-Treated Human Lymphocyte Cultures

Abstract: When human lymphocyte cultures are exposed to EB (10μg/ml) for 2 hr prior to fixation, there is a marked increase in frequency of early mitotic cells, possibly due to the prolongation of the prophase-metaphase transition This procedure may serve as a simple method for obtaining a large number of cells with extremely elongated chromosomes, which would permit a great precision of human chromosome analyses

Hydrographic features of the deep water of the Bering Sea—the sea of Silica

Abstract: The deep water of the Bering Sea contains concentrations of dissolved silicate up to 240 μg at. Sil−1. Nitrate concentrations are less than in the North Pacific at the depths with the same oxygen contents. The rates of chemical and biochemical reactions occurring in the deep water (below 2km) were estimated from hydrographic data by applying a modified one-dimensional model. Oxidation of organic matter in the oxygenated water column of the Bering Sea was twice that of the North Pacific. Silicate regeneration, or dissolution of biogenic opal and denitrification, or bacterial nitrate reduction to gaseous nitrogen, on and in the bottom sediments of the deep Bering Sea basin were calculated to be 212 and 20 mg at.m−2 yr−1, respectively. These values are consistent with the ones estimated from vertical profiles of dissolved silicate and nitrate in the interstitial water of the sediments. The chemical anomaly observed in deep water of the Bering Sea can be produced by these reactions in the bottom sediments. The decomposition of organic matter in anoxic sediments accounts for about 8% of the total organic matter decomposing in the water column below 2km and in the sediments.

Effective Interaction with Three-Body Effects

Abstract: Three-body effects, which are effects of three-body force and three-hotly correlation, are introduced into the two-body nuclear force in a semi-phenomenological way to reproduce the nuclear saturation over all nuclei by the lowest order Brueckner theory. On the hasis of the reaction matrix calculation of nuclear matter with this two-body force including the three· body effects, a new effective potential is proposed which includes two independent parameters, namely, nuclear density and starting-energy. Because of the effect of three-body force, this effective potential is more attractive in the 'E state, compared with the usual one, and assures overall saturation without any artificial modification. The starting-energy dependence of the effective potential is also strengthened by the three- body force. The starting-energy dependence is found to work well for nuclear saturation together with the density dependence. Present density dependence is weaker than that of the usual clensity dependent effective potentials. The effective potential is decomposed into central, spin-orbit and tensor components.

Drug-carrier Property of Albumin Microspheres in Chemotherapy. II. Preparation and Tissue Distribution in Mice of Microsphere-entrapped 5-Fluorouracil

Abstract: Bovine serum albumin microspheres contatining 5-fluorouracil-6-3H were prepared by heating at 180° (or 150°, 100°) of 25% albumin solution in cottonseed oil emulsion. The shape of this microsphere was invariably spherical, and the average diameter was 0.66μ. After intravenous injection in mice, 5-fluorouracil-6-3H entrapped in albumin microspheres localized mainly in the liver, and the disappearance rate of radioactivity in microspheres from the tissue was very slow in comparison with that of free drugs. The microsphere might be delivered into reticuloendothelial system in the liver because ofits phagocytic activity, as well as the distribution following injection of albumin macroaggregates. Such preferential localization and sustained release of entrapped drugs suggested that albumin microspheres are useful as drug-carrier in chemotherapy.

Evidence for two B-cell alloantigen loci in theHLA-D Region

Abstract: Antigenic determinants recognizable by human antisera (Hon 7 and 2075abs sera) were found in a partially purified antigen preparation obtained from an HLA-D and -DR homozygous cell line (EBV-Wa). Sequential coprecipition tests showed that two determinants detectable with Hon 7 and 2075abs sera (Hon 7 and 2075abs determinants) were present on different molecules. These two antigenic determinants were shown to be allotypic and were expressed predominantly in the B-cell-rich fraction. Family studies showed that both antigenic determinants segregated concordantly with respectiveHLA haplotypes. In the population study, the 2075abs and Hon 7 determinants were shown to be in strong linkage disequilibrium and the 2075abs determinant perfectly correlated with the HLA-DRw4 specificity. The results indicate that the Hon 7 determinant is coded for by a gene distinct from alleles at theHLA-DR locus. Furthermore, the locus (Hon 7) coding for the Hon 7 determinant is suggested to be very closely linked with theHLA-DR locus.

Viral xenogenization of intact tumor cells.

Abstract: Publisher Summary Tumor immunotherapy modifies tumor cells so that they become more foreign to the host. This chapter explores the ways investigators have attempted to make tumor cells foreign to the host by increasing their antigenicity. It reviews attempts to induce new foreign proteins on tumor cells and to increase the antigenicity of existing tumor-specific or tumor-associated antigens (TSA or TAA) on tumor cells. By both of these methods tumor cells can be made more highly immunogenic or more easily immunosensitive to the immune responses of the host. Tumor cells show low antigenicity and are not readily recognized as foreign by the host. By the process of xenogenization of tumor cells infected with a nonlytic budding murine virus, the regression of tumors is caused when inoculated into normal hosts owing to an acquisition of virus-specific antigen that is foreign in the host. Xenogenization is used to describe the process of making a tumor cell antigenically foreign to the host. Studies performed on tumor cells that have been infected with a nonlytic budding virus are summarized in the chapter. It also discusses the acquisition of a virus-specific new antigen in tumor cells.

Studies on Chitin. III. Preparation of Chitin Fibers

Abstract: The chitin fiber was obtained from a chitin-formic acid solution which was found to be spinnable. This solution was prepared through repeated freezing process by the addition of dichloroacetic acid and isopropyl ether. Dichloroacetic acid and methanesulfonic acid were also found to be solvents for chitin, though the spinnability could not be observed owing to rapid reduction of viscosity even at low temperature. Chitin fibers were successfully prepared from formic acid solution, and better qualities were found for these than for the fibers prepared through the chitin viscose. X-Ray diffraction analysis suggested that the regenerated chitin would have a similar structure to the natural chitin. The clear and flexible chitin film was prepared from formic acid–dichloroacetic acid or formic acid–urea solution by casting on a glass plate and solidifying in ethanol.

Marine Terpenes and Terpenoids. I. Structures of Four Cembrane-type Diterpenes : SarCophytol-A, Sarcophytol-A Acetate Sarcophytol-B, and Sarcophytonin-A, from the Soft Coral, Sarcophyton glaucum

Abstract: The lipid extract of the soft coral, Sarcophyton glaucum, was found to contain significant amounts of cembrane-type diterpenes. The structures of four major components, sarcophytol-A, sarcophytol-A acetate, sarcophytol-B, and sarcophytonin-A were characterized on the basis of spectral data and degradative studies by ozonolysis. Sarcophine and 16-deoxosarcophine, which were reported to be abundant in S. glaucum collected in the Red Sea, were not found yet.

Pitting corrosion for retaining acrylic resin facings.

Abstract: 1. Pitting corrosion provides undercuts suitable for retaining a resin facing. 2. Using a cathode with a proper shape, pits were uniformly distributed on the surface of a metal casting. The size of pits varies, depending on the time of pitting treatment. 3. The retentive pits were excellent in both retentive strength and marginal sealing when compared with spherical powder and beads.