4] Periodate methods: Determination of compounds oxidized to carbonyl acids

A simple technique is described for the ultrastructural localization of periodate-reactive mucosubstances and polysaccharides containing 1,2-glycols in thin sections of routinely fixed tissues. In this method the sugar residues are oxidized by periodic acid and the resulting aldehydes presumably reduce chelated bismuth subnitrate to metallic bismuth which then appears as a fine electron-opaque precipitate at the sites of the reducing sugars. The periodic acid-alkaline bismuth procedure provides a high resolution electron microscopic technique for demonstrating tissue sites of periodate-engendered groups very similar to the light microscopic periodic acid-Schiff reaction. The reaction can be prevented by the omission of periodate oxidation or alkaline bismuth subnitrate and by aldehyde blockage with the blocking agent, m-aminophenol. However, glycogen stains markedly without prior periodate oxidation, presumably through chelation of bismuth by hydroxyl groups. Other structures which stain without prior periodate oxidation are liver lysosomal dense bodies and, occasionally, ribosomes.

Determination of carbonyl acids formed upon periodate oxidation II. Analysis of various carbonyl acid precursors

Mechanism and rate of anomalous extraction of chloride salts from water to 1,2-dichloroethane

Applications of bio-oil are limited by its challenging properties including high moisture content, low pH, high viscosity, high oxygen content, and low heating value. Separation of switchgrass bio-oil components by adding water, organic solvents (hexadecane and octane), and sodium hydroxide may help to overcome these issues. Acetic acid and phenolic compounds were extracted in aqueous and organic phases, respectively. Polar chemicals, such as acetic acid, did not partition in the organic solvent phase. Acetic acid in the aqueous phase after extraction is beneficial for a microbial-electrolysis-cell application to produce hydrogen as an energy source for further hydrodeoxygenation of bio-oil. Organic solvents extracted more chemicals from bio-oil in combined than in sequential extraction; however, organic solvents partitioned into the aqueous phase in combined extraction. When sodium hydroxide was added to adjust the pH of aqueous bio-oil, organic-phase precipitation occurred. As the pH was increased, a bi...

We succeeded in developing of a new method for in vitro poly(3-hydroxybutyrate) (P(3HB)) synthesis with coenzyme A (CoA) recycling. Thiophenyl (R)-3-hydroxybutyrate was used as a precursor for the monomer, (R)-3-hydroxybutylCoA ((R)-3HBCoA). The (R)-3HBCoA was synthesized by the ester exchange reaction between thiophenyl (R)-3-hydroxybutyrate and CoA. Although the polymerization reaction in the buffer (water phase) was performed, the reaction did not occurred. The results of a PHA synthase assay in the presence of thiophenol suggested that the reaction was inhibited by a small amount of thiophenol. To avoid the inhibition of PHA synthase by thiophenol, a water−organic solvent two-phase reaction system was developed for the polymerization reaction. The water−organic solvent two-phase reaction system has been used previously for the bioconversion of substrates with low solubility in water; it was used to remove thiophenol released during the ester exchange reaction from the water phase. Thiophenyl (R)-3-hydroxybutyrate and PHA synthase were dissolved in the organic solvent and water phases, respectively. Ester exchange between thiophenol and CoA occurs at the interface of water and the organic solvent phase, and the (R)-3HB 3-hydroxybutylCoA synthesized was polymerized sequentially by PhaC. The organic solvents with high a logPow of more than 3.9 such as hexane, octane, decane, or dodecane were found to be suitable for the organic solvent phase in the two-phase system. The polymerization reaction mixture showed signs of turbidity in 2 h, after which white precipitates formed. The structural analyses by 1H NMR spectroscopy indicated that the product was P(3HB). The weight-averaged molecular weight and molecular weight distribution of P(3HB) synthesized were found to be 1.6 × 106 and 2.9, respectively. The maximum yield of P(3HB) based on thiophenyl (R)-3-hydroxybutyrate was 47%.

Mucin histochemistry of experimental gastric cancers induced in rats by N-methyl-N'-nitro-N-nitrosoguanidine or 4-nitroquinoline 1-oxide was analysed by labelled lectin staining for concanavalin A (Con A) after prior periodate oxidation (paradoxical Con A staining) or Arachis hypogarea agglutinin (peanut lectin, PNA) with or without prior periodate oxidation. In the digestive tracts of control-group rats the mucins were classified into class II or III by paradoxical Con A staining. Class II mucins were found in surface mucous cells, goblet cells and the surface coat of intestinal absorptive cells, while class III mucins were present in mucous neck cells, pyloric gland cells and Brunner's gland cells. Although class III mucins showed PNA reactivity, those in pyloric gland cells selectively lost positive staining after 1-4 h oxidation with periodate. Thus phenotypic expression of class III mucin-positive cells in the gastric mucosa could be further classified into mucous-neck-cell type and pyloric-gland-cell type on the basis of this sensitivity to periodate oxidation. Metaplastic cells in fundic mucosa and almost all class III mucin-positive cells in adenomatous hyperplasias, well-differentiated adenocarcinomas and signet-ring cell carcinomas, which developed in both fundic and pyloric mucosae, showed pyloric gland phenotypic expression.

Role of water in the mechanism of the salt extraction to the organic solvent

The effect of aliphatic alcohols upon the dissociation of micrococcus lysodeikticus membrane lipids and proteins

Solvent selection in the preparation of poly( dl-lactide) microspheres prepared by the solvent evaporation method

Review: 43 refs.

Multiphase reaction media involving water and carbon dioxide for selective hydrogenation

Distribution of binary mixtures of citric, acetic and oxalic acid between water and organic solutions of tri- n-octylamine Part I. Organic solvent toluene

Binding sites for three fucose specific lectins, Aleuria aurantia agglutinin (AAA), Lotus tetragonolobus agglutinin (LTA) and Ulex europeus I agglutinin (UEA I), were investigated in sections from normal human and rat muscles, in muscle from patients with Duchenne muscular dystrophy (DMD) and in denervated and devascularized rat muscle. In normal human and rat muscle AAA detected fucosylated glycocompounds in the sarcoplasm, sarcolemma, interfibre connective tissue and vascular structures. In normal human muscle addition of fucose to the AAA incubation medium or treatment of the sections with formaldehyde followed by periodic oxidation before lectin incubation strongly inhibited the staining at all sites other than endothelial cells. In normal rat muscle the same staining procedures strongly inhibited the AAA binding at all sites other than the sarcolemma. Incubation with LTA resulted in a diffuse reaction around the vascular structures in rat muscle, while in human muscle a moderate, homogeneous staining was present in all muscle fibres. Treatment of the sections with formaldehyde and periodic acid before incubation with LTA resulted in strongly labelled muscle capillaries in both human and rat muscle. The only elements in the muscle tissues that were stained with UEA I were human endothelial cells. In denervated and devascularized rat muscle incubation with AAA revealed a novel fucose expression that appeared intracellularly in some necrotic fibres. The AAA-positive fucose residues in the sarcolemma of normal muscle fibres that were resistant to periodic acid oxidation could not be shown by AAA in denervated muscle. In DMD muscle a cryptic sarcolemmal fucose expression could be shown with AAA.(ABSTRACT TRUNCATED AT 250 WORDS)

A thermodynamic model for reactive extraction of macro amounts of zirconium and hafnium with TBP

Organisation and heterogeneous photoreactivity of water-soluble zinc meso-tetrakis(4-carboxyphenyl) porphyrin (ZnTPPC) were investigated at polarisable liquid / liquid interfaces by systematically varying the organic phase solvent. The remarkable affinity of ZnTPPC for the molecular interfacial boundary manifested itself by modulations in the surface excess charge. Potential dependence of interfacial coverage of the porphyrin appeared to be affected by the nature of the organic phase solvent. Heterogeneous photoinduced ET between the specifically adsorbed porphyrin molecules and the redox species present in the organic solvent manifests itself as photocurrent responses. Photocurrent responses are also found to be strongly dependent on the nature of the organic phase solvent. Variations in the photocurrent magnitude were rationalised in terms of the interfacial organisation of the porphyrin and the phenomenological electron transfer rate constant using a modified Marcus model. Formation of a self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) on gold electrode was investigated by Kelvin probe technique and electrochemical impedance spectroscopy as a function of immersion time in thiol solution. Kelvin probe measurements exhibited a monotonic increase in surface potential with immersion time. The increase in surface potential was attributed to the formation of gold-thiolate bonding. Maximum coverage of thiol molecules were obtained after an immersion time of 10 h. Double-layer capacitance (Cdl) values of thiol modified electrodes were extracted from the impedance measurements as a function of immersion time. Furthermore, Cdl values dropped significantly and reached a constant value within a short immersion time in thiol. Multilayer film of pLys and pGlu was fabricated on MUA modified gold electrodes. Polyelectrolyte modified electrodes displayed characteristics electrochemical features of diffusion through pinholes. Photocurrent responses originating from the porphyrin sensitised ultrathin polyelectrolyte multilayer assembly is investigated as a function of bias potential and illumination light intensity. Redox couples incorporated within the multilayer assembly act as carriers of the photogenerated charges across the film. The incident photon to current conversion efficiency (IPCE) of porphyrin sensitised multilayer assemblies is estimated to be 0.02%. Finally, electrochemical and optical properties of metal nanoparticle architectures on pLys modified gold electrodes were investigated. Monodispersed randomly distributed arrays of Au nanoparticles were formed upon electrostatic deposition from solution. Kelvin probe measurements exhibited a steady increase in compensation potential difference (CPD) with deposition time which reached a plateau after 4 h. From the scanning electron micrographs, we estimated maximum particle coverage of 8.6 × l010cm-2 separated by an average edge-to-edge separation of 25 nm from the nearest neighbour. The plasmon resonance band of Au nanoparticles in the ensemble featured a shift to longer wavelengths and were broader compared to that of colloidal particles in aqueous solution. Cyclic voltammetry and impedance measurements indicated strong electronic coupling between the nanoparticles in the ensemble and the electrode. Furthermore, fabrication of a three-dimensional assembly of metal nanoparticles and pLys using electrostatic layer-by-layer method is also illustrated.