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At least 1,387 records · Page 77Linked to original sources
PubMed2005

A new amide from Asarum forbesii Maxim.

A highly unsaturated new amide, (2E,4Z,8Z,10Z)-N-isobutyl-2,4,8,10-dodecatetraenamide (1), was isolated in very small quantities from the whole plant of Asarum forbesii Maxim. together with four known compounds, (2E,4E,8Z,10E)-N-isobutyl-2,4,8,10-dodecatetraenamide (2), (-)-sesamin (3), (-)-asarinin (4) and (E)-asarone (5). The Z/E isomers, 1 and 2, were separated successfully by developed silver-ion medium-pressure liquid chromatography (SIMPLC). Compound 2 and the two diastereoisomers, 3 and 4, were isolated from this plant for the first time. The characterization of these compounds was achieved by various spectroscopic methods.

Amides↗
PubMed2006

Are multidose over-the-counter artificial tears adequately preserved?

PURPOSE: To investigate artificial tears containing different preservatives for antimicrobial efficacy. Based on the challenge test outlined in the European Pharmacopoeia, products were tested in their original containers to see whether their component preservative had sufficient activity. METHODS: Five brands of over-the-counter artificial tears each containing different preservatives (benzalkonium chloride/EDTA, parabens, chlorobutanol, silver chloride complex, and Purite-stabilized oxychloro complex) were inoculated with test microorganisms (Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans). Changes in the microbial start concentration with time were followed by plating onto growth media to provide a measure of the preservative efficacy. In another test, artificial tears were applied to paper disks that were then placed onto agar growth media seeded with microorganisms. Zones of inhibition were measured after incubation. RESULTS: Only the brand of artificial tears containing benzalkonium chloride/EDTA satisfied the major criteria for antimicrobial preservation for all the test microorganisms. Only a benzalkonium chloride/EDTA-containing disk placed on agar seeded with S. aureus produced a zone of inhibition in the agar diffusion test. CONCLUSION: The brand of artificial tears containing benzalkonium chloride/EDTA is suitable for sale in countries adopting the monographs of the European Pharmacopoeia. Other brands would only be suitable for sale if justified reasons for not meeting the major criteria for preservative efficacy can be provided.

Benzalkonium Compounds↗
PubMed1991

Interfacial thermodynamics of protein adsorption and ion co-adsorption. III. Electrochemistry of bovine serum albumin adsorption on silver iodide.

An experimental analysis of charge regulation in protein adsorption is presented. The model system consists of colloidal particles of the slightly water soluble salt silver iodide as the adsorbent and the protein bovine serum albumin as the adsorbate. Protein adsorption experiments corroborate earlier findings that albumin adsorbs maximally close to the isoelectric point of the protein. The adsorption is reversible with respect to protein-protein exchange. The charge regulation is studied by novel potentiometric titrations. The Galvani potential of the adsorbent, partially covered with protein, is varied by the addition of AgNO3/KI while the pH is kept constant by means of a pH-stat. It is shown that the ion co-adsorption is a linear decreasing function of the blank surface charge density. The results are consistent with thermodynamics: for the first time a few phenomenological linkage relations between the ion co-adsorptions and chemical potentials are verified experimentally. The charge regulation is interpreted in terms of a contact layer model, which explains the ion co-adsorption by compounded ion exchange equilibria in the small layer of atomic contact between adsorbed protein and surface.

Adsorption↗
PubMed2001

First evidence for the use of organosilver compounds in Pd-catalyzed coupling reactions; a mechanistic rationale for the Pd/Ag-catalyzed enyne synthesis?

Silver acetylides have been prepared and used in Pd-catalyzed coupling reactions. Enynes have thus been obtained in good yields. This work demonstrates that organosilver compounds could enter the Pd catalytic cycle; it also supports the role of silver acetylides as intermediates in the new Pd/Ag-catalyzed coupling reaction.

Journal Article↗
PubMed2003

Increased intensities of YOYO-1-labeled DNA oligomers near silver particles.

DNA detection is usually performed using fluorescence probes. Using a DNA oligomer stained with the widely used dye 1,1'-[1,3-propanediylbis[(dimethylimino)-3,1-propanediyl]]bis[4-[(3-methyl-2(3H)-benzoxazolylidene)methyl]]-quinolinum tetraiodide (YOYO-1), we show that a substrate containing silver particles can lead to a greater than 10-fold increase in the fluorescence intensity. Proximity to silver particles also increases the photostability of YOYO-1-DNA. These results suggest that substrates or gels containing silver particles may be used for increased sensitivity in DNA detection.

Base Sequence↗
PubMed2005

Hollow gold nanoparticles encapsulating horseradish peroxidase.

Hollow nanoshells of gold entrapping an enzyme, horseradish peroxidase (HRP), in the cavity of the nanoshell have been prepared in the reverse micelles by leaching out silver chloride (AgCl) from Au(shell)AgCl(core) nanoparticles with dilute ammonia solution. The particles have been characterised by dynamic laser light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and electron diffraction. The particle size is below 100 nm diameter, depending upon the size of the aqueous core of reverse micelles in which these particles have been prepared. This soft-chemical method for the preparation of such particles allows the entrapped enzyme to remain active inside the hollow gold nanoparticles. Small substrate molecules such as o-dianisidine can easily enter through the pores of the nanoshell and can undergo enzymatic oxidation by H2O2. The enzyme kinetics follows Michaelis-Menten mechanism. When the substrate is chemically conjugated with dextran molecule (10 kDa), the enzymatic reaction is practically completely prevented perhaps by the inability of dextran-o-dianisidine conjugate to penetrate the pores of the nanoshells. However, HRP did not show any activity when trapped inside solid gold nanoparticles.

Ammonia↗
PubMed1983

Gas chromatographic alkylation studies of phenytoin, mephenytoin and primidone: investigation of butylated derivatives.

The alkylation of phenytoin, mephenytoin and primidone with n-alkyl iodides in N,N-dimethylacetamide with tetramethylammonium hydroxide was investigated by gas chromatography. With methyl iodide phenytoin and mephenytoin were each converted into a single derivative; the use of other alkyl iodides yielded more than one product. Primidone was converted with methyl iodide and butyl iodide into a major derivative (> 90%) and a minor one. Butylation of the compounds by this method was compared with butylation in an acetone-butyl iodide mixture with potassium carbonate, caesium carbonate or silver oxide added, and with on-column butylation. All these methods resulted in the production of more than one derivative. The derivatives were identified by mass spectrometry and by 1H NMR and 13C NMR. With the acetone-butyl iodide-silver oxide method the main derivatives were O-butylated compounds. The other methods yielded predominantly N-butylated derivatives.

Journal Article↗
PubMed2004

[Effect of cerium nitrate supplementation to silver sulfathiazole preparations on survival of planctonic and attached to the dermis Staphylococcus aureus cells].

The purpose of this study was to evaluate the influence of preparations containing silver sulfathiazole, with or without cerium nitrate, on survival of Staphylococcus aureus. In the first step, sensitivity of the planctonic bacteria to the tested compounds was determined. Addition of cerium nitrate enhanced the antibacterial activity of silver sulfathiazole by 4 times, as evidenced by MIC and MBC values. For the estimation of antibacterial activity of the mentioned chemotherapeutic on attached bacteria in vitro model of an "infected wound" was applied. Sensitivity of bacteria attached to the dermis was lower than sensitivity of planctonic bacteria. Kinetics of the release of chemotherapeutic compounds incorporated into a collagen dressing was the most effective for the combination of silver sulfathiazole with cerium nitrate.

Anti-Infective Agents, Local↗
PubMed1997

The effect of some metal ions on volatile sulfur-containing compounds originating from the oral cavity.

Halitosis originates mainly from the oral cavity, and the volatile sulfur-containing compounds (VSC) are the major contributors of the unpleasant odor. Anaerobic G- bacteria use sulfur-containing amino acids in their production of VSC. Zinc has been shown to inhibit production of odiferous VSC, and the mechanism proposed has been that zinc, with its affinity for sulfur, oxidizes thiol groups and thereby inhibits the precursors of VSC. The aim of the study was to investigate whether, and to what extent, other metal ions with affinity for sulfur exert the same effect and whether a correlation exists between the sulfur affinity and VSC-inhibiting activity of these metals. VSC levels were measured on the 'morning breath' of 10 test subjects, using a portable sulfide monitor. The mouthrinses tested were aqueous solutions of zinc chloride, zinc citrate, stannous fluoride, cuprous gluconate, ferrous gluconate, and silver acetate, and they contained equimolar amounts of metals (1.47 mmol/I). The results showed that the ranking of Zn++ and Sn++ differed in the clinical test compared with sulfur affinity, and likewise with Ag+ and Fe++. It may therefore be concluded that there is no positive correlation between the inhibiting effect of metal ions on VSC and their affinity for sulfur.

Acetates↗
PubMed2001

Melanization of Cryptococcus neoformans reduces its susceptibility to the antimicrobial effects of silver nitrate.

Cryptococcus neoformans is a human pathogenic fungus that is frequently found in avian feces and Eucalyptus trees. There is evidence that C. neoformans can make a melanin-like pigment in pigeon excreta, a major natural environmental niche. Silver nitrate, AgNO3, is a highly toxic compound for bacteria and fungi. In this study we investigated the effects of melanin production by C. neoformans on the susceptibility of this fungus to AgNO3. C. neoformans was grown in media with and without the melanin precursor, L-dopa, for various times and susceptibility to AgNO3 was determined by measuring percentage of survival after incubation in AgNO3. There was an inverse association between time allowed for melanization and susceptibility to Ag+. Addition of melanin particles to a suspension of non-melanized C. neoformans cells reduced their susceptibility to AgNO3, consistent with metal ion chelation by melanin. Binding of Ag+ to melanin particles was demonstrated by atomic absorption spectroscopy. The results indicate that melanization of C. neoformans reduces susceptibility to a toxic heavy metal. This suggests a role for melanin in environmental protection against heavy metal toxicity.

Anti-Bacterial Agents↗
PubMed1976

Phase identification of dental amalgam using transmission electron microscopy.

Dental amalgam specimens were polished and afterward etched by an acid iodine solution. The replicas were obtained by the vacuum coating technique. The electron micrographs indicated that it was possible to identify the silver-mercury (gamma1) and tin-mercury (gamma2) intermetallic compounds formed during amalgam setting.

Dental Amalgam↗
PubMed1975

Distribution of various labeled thioglucoses in rodents.

Gold, silver and lead thioglucose were evaluated in rodents to determine the value of organo-metallic compounds in the study of metabolic abnormalities. Increased radioactivity concentration was noted in the hypothalamus with all compounds. Gold thioglucose concentrated in the kidneys and thymus, and 203Pb-thioglucose concentrated in the pancreas and thymus.

Adrenal Glands↗
PubMed1995

Reductive dehalogenation of bromoform in aqueous solution.

The hybrid semiconducter-macrocycle catalyst TiO2-cobalt phthalocyanine promotes the solar photolysis of aqueous bromoform under anaerobic conditions. The major decomposition products are dibromoethane and HBr. Bromomethane and methane were produced only after prolonged photolysis (30 hr). Acetone, derived from added 2-propanol, was the only observed oxidation product. Preliminary experiments showed that electrolytic reduction of aqueous carbon tetrachloride at a vitamin B12-modified silver electrode produced the expected lower homologues but with surprisingly high yields of methane.

Chemical Phenomena↗
PubMed2005

Betaine-induced assembly of neutral infinite columns and chains of linked silver(I) polyhedra with embedded acetylenediide.

Ten polymeric silver(I) double salts containing embedded acetylenediide: [(Ag2C2)2(AgCF3CO2)9(L1)3] (1), [(Ag2C2)2(AgCF3CO2)10(L2)3]H2O (2), [(Ag2C2)(AgCF3CO2)4(L3)(H2O)]0.75 H2O (3), [(Ag2C2)(1.5)(AgCF3CO2)7(L4)2] (4), [(Ag2C2)(AgCF3CO2)7(L5)2(H2O)] (5), [(Ag2C2) (AgC2F5CO2)7(L1)3(H2O)] (6), [(Ag2C2)(AgCF3CO2)7(L1)3(H2O)]2 H2O (7), [(Ag2C2)(AgC2F5CO2)6(L3)2] (8), [(Ag2C2)2(AgC2F5CO2)12(L4)2(H2O)4]H2O (9), and [(Ag2C2)(AgCF3CO2)6(L3)2(H2O)]H2O (10) have been isolated by varying the types of betaines, the perfluorocarboxylate ligands employed, and the reaction conditions. Single-crystal X-ray analysis has shown that 1-4 all have a columnar structure composed of fused silver(I) double cages, with C2(2-) species embedded in its stem and an exterior coat comprising anionic and zwitterionic carboxylates. For 5 and 6, single silver(I) cages are linked into a beaded chain through both types of carboxylate ligands. In 7, two different coordination modes of L1 connect the silver(I) polyhedra into a chain. For 8, the mu(2)-O,O' coordination mode of L3 connects the silver(I) double cages into a chain. Compound 9 exhibits a two-dimensional architecture generated from the cross-linkage of double cages by C2F5CO2-, L4, and [Ag2(C2F5CO2)2] units. Similar to 9, 10 is also a two-dimensional structure, which is formed by connecting the chains of linked double cages through [Ag2(CF3CO2)2] bridging.

Journal Article↗
PubMed2001

Exogenous ACC enhances volatiles production mediated by jasmonic acid in lima bean leaves.

We report the synergistic effects of exogenous 1-aminocyclopropane-1-carboxylic acid (ACC) and jasmonic acid (JA) on production of induced volatiles by excised lima bean leaves. Application of ACC alone to leaves induced trace amounts of volatiles. ACC positively affected three JA-induced volatiles, (E)- and (Z)-beta-ocimene, and (Z)-3-hexenyl acetate. The ethylene inhibitor, silver thiosulfate, inhibited the production of these compounds. The results suggest synergistic effects of JA and ACC on inducible volatile production by lima bean leaves. Furthermore, lima bean leaves treated with JA plus ACC became more attractive to predatory mites, Phytoseiulus persimilis, than those treated with JA alone.

Acari↗