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At least 397 records · Page 22Linked to original sources

Human generalized argyria: a submicroscopic and X-ray spectroscopic study.

A 58-year-old man presented with a slate-gray discoloration of the skin. The patient had no medical complaint apart from the increasing cosmetic disability. He gave no drug history and denied professional exposure to chemical compounds. General medical examination was noncontributory; routine laboratory data were within the normal range. Light microscopy revealed the presence of numerous, small, pigmented particles at the dermal level. The submicroscopic investigation showed that the granules were deeply electron dense, had an irregular polycyclic contour, and varied in size between 100 and 600 nm. They were predominantly located in relation to the basal laminae of the epidermis and the cutaneous appendages, and in the dermal elastic fibers. In addition, the authors were able to document the presence of silver particles lying free in the cytoplasm of both epithelial cells of the secretory segment of eccrine sweat glands and mastcells, findings that have never been reported so far. X-ray spectroscopy documented that the electron-opaque particles contained silver, with some differences in the elemental composition of the granules, according to their location. These novel findings expand the knowledge of the various mechanisms of interaction of silver with the cellular and extracellular environment and allow some speculations about possible mechanisms of silver detoxification.

Argyria↗

[Characterization of Ru(bpy)(3)2+ and Ru(phen)(3)2+ complexes with silver(i) ion of ground state in propylene-carbonate].

Phosphorescent bimolecular and termolecular exciplexes of 3Ru(bpy)(3)2+ and Ru(phen)(3)2+ (bpy = 2,2'-bipyridine, and phen = 1,10-phenathroline) formed by silver ions of ground state in propylene carbonate solution are identified and characterized. Formation constants, lifetime, radiative and non-radiative decay constats of exciplexes are determined. Temperature-dependent luminescence lifetime measurements have revealed that exciplex formation causes a decrease in the energy level of the luminescent excited state.

Cross-Linking Reagents↗

Ultrastructural localization of argyrophilic substances in diffuse plaques of Alzheimer-type dementia demonstrated by methenamine silver staining.

The ultrastructure of argyrophilic substances in diffuse plaques of an Alzheimer-type dementia brain was examined using methenamine silver (MS) electron microscopy with the pre-embedding method. Electron-dense substances, which were sparse aggregations of bundle-like structures with silver granules, were disseminated in the diffuse plaques. Comparison of serial MS and routine ultrathin sections revealed that diffuse plaques usually show scattered bundles of amyloid fibrils or amorphous materials, or both, between indistinct cell process membranes. Some of these processes were identified as astrocytic or dendritic in origin. A few degenerative neurites were frequently noted in large silver-positive areas but never in small areas. These findings suggest that the appearance of amyloid fibrils and amorphous materials between certain cell processes is a very early morphological change in the process of senile plaque formation.

Aged↗

A comparison of silver stain and SYPRO Ruby Protein Gel Stain with respect to protein detection in two-dimensional gels and identification by peptide mass profiling.

Proteomic projects are often focused on the discovery of differentially expressed proteins between control and experimental samples. Most laboratories choose the approach of running two-dimensional (2-D) gels, analyzing them and identifying the differentially expressed proteins by in-gel digestion and mass spectrometry. To date, the available stains for visualizing proteins on 2-D gels have been less than ideal for these projects because of poor detection sensitivity (Coomassie blue stain) or poor peptide recovery from in-gel digests and mass spectrometry (silver stain), unless extra destaining and washing steps are included in the protocol. In addition, the limited dynamic range of these stains has made it difficult to rigorously and reliably determine subtle differences in protein quantities. SYPRO Ruby Protein Gel Stain is a novel, ruthenium-based fluorescent dye for the detection of proteins in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels that has properties making it well suited to high-throughput proteomics projects. The advantages of SYPRO Ruby Protein Gel Stain relative to silver stain demonstrated in this study include a broad linear dynamic range and enhanced recovery of peptides from in-gel digests for matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry.

Acrylic Resins↗

Nanoleakage of dentin adhesive systems bonded to Carisolv-treated dentin.

The hybrid layer created in caries-affected dentin has not been fully elucidated and may influence bond durability. This study investigated the nanoleakage patterns of caries-affected dentin after excavation with Carisolv or conventional instruments treated with one of three adhesive systems. Flat occlusal dentin surfaces, including carious lesions, were prepared from extracted human molars and finished with wet 600-grit silicon carbide paper. Carious dentin was removed with Carisolv or round steel burs in conjunction with Caries Detector. PermaQuik, Single Bond or One-Up Bond F was bonded to the excavated dentin surfaces and adjacent flat occlusal surfaces and it was covered with Silux Plus resin-based composite. After 24-hour storage in 37 degrees C water, the bonded interfaces were polished to remove flash, and the surrounding tooth surfaces were coated with nail varnish. Specimens were immersed in 50% (w/v) silver nitrate solution for 24 hours, exposed to photo developing solution for eight hours, then sectioned longitudinally through the bonded, excavated dentin or "normal" dentin surfaces. The sectioned surfaces were polished, carbon coated and observed in a Field Emission-SEM using back scattered electrons. Silver deposition occurred along the base of the hybrid layer for all specimens. However, Single Bond showed a greater density of silver deposition in the caries-affected dentin compared with normal dentin. PermaQuik had a thicker hybrid layer in caries-affected dentin than normal dentin. One-Up Bond F exhibited a thin hybrid layer in normal dentin, but the hybrid layer was often difficult to detect in caries-affected dentin.

Acid Etching, Dental↗

An experimental and theoretical evaluation of the reactions of silver hyponitrite with phosphorus halides. In search of the elusive phosphorus-containing hyponitrites.

In the reaction of F2PBr, F2P(O)Br, (C6F5)2PBr, (CH3)2P(S)Br, and (CH3)2P(O)Cl with silver hyponitrite (AgON=NOAg), nitrous oxide (N2O) and mu-oxo phosphorus species were obtained in all cases rather than the plausible hyponitrite alternative. Theoretical calculations of the geometries and expected decomposition pathways of the phosphorus-containing hypothetical hyponitrites were carried out at the B3LYP/6-311+G(2df)//B3LYP/6-31+G(d) level. The cis-hyponitrite, XON=NOX (X=PF2, OPF2), is predicted to concertedly decompose to N2 plus phosphorus-containing radicals (OPF2, O2PF2) or to N2O plus the mu-oxo phosphorus species, X-O-X, (X=PF2, OPF2) with the former pathway having a smaller activation barrier (4.6 kcal/mol, X=PF2; 10.5 kcal/mol, X=OPF2). On the other hand, trans-hyponitrite can only decompose to N2 plus the phosphorus-containing radicals, because there is a very high barrier for rearrangement to cis-hyponitrite. These results are in disagreement with experiment, because only the mu-oxo phosphorus species are observed. Reconciliation between experiment and theory is made for X=OPF2 when a silver cation is included in the calculations. In THF (as a model for neat F2P(O)Br), the silver cation is predicted to reverse the order of the two transition states through stronger interactions with the oxygen atoms in the transition state of the N2O-producing pathway. Thus, Ag(I) is predicted to be not only catalytic for X=OPF2 but also product-specific toward the mu-oxo products.

Catalysis↗

Scanning electron microscopy of uncoated human metaphase chromosomes.

Human metaphase chromosomes were processed with a 3% glutaraldehydetannic acid technique and examined in a scanning electron microscope at 20 kV either without added metal coating or with 2 nm of sputtered gold coating. Several substrates--aluminum mnium foil, silver mirror deposit and sputtered gold-provided good conductive backgrounds for chromosomal spreads. Silver mirror deposit was the best conductive substrate tested. This method should prove to be a useful tool for monitoring the three-dimensional morphology of mitotic chromosomes with the possibility of studying various banding techniques, chromosomal uncoiling and secondary constrictions currently being examined in chromosomal studies.

Aluminum↗

[The dynamics of the healing of experimentally reproduced bone defects filled with different polyacrylamide gel-based compounds].

Time course of healing of standard osseous defects by introduction of polyacrylamide gel (PAG)-based materials was studied in rat experiments. PAG did not prevent the formation of soft-tissue and osseous regenerate in bone defects. Addition of hydroxyapatite, bactericidal agent, and lysozyme to PAG-based composition led in some cases to development of chronic inflammation and giant-cell reaction in osseous wound and to inhibition of the reparative processes.

Acrylic Resins↗

Enhanced lanthanide luminescence using silver nanostructures: opportunities for a new class of probes with exceptional spectral characteristics.

The photophysical effects of europium tetracycline immobilized in thin polyvinyl alcohol films coated onto silver nanostructures have been investigated. Complimentary to recent reports from our laboratories that the close proximity of luorophores to silver nanostructures can enhance their intrinsic radiative decay rate, we show that up to a 16-fold enhancement in lanthanide luminescence is possible, accompanied by a notable reduction in luminescence lifetime. These results suggest the potential future development of a new class of significantly brighter lanthanide based probes with exceptional spectral properties, which can probably undergo significantly more excitation-emission event cycles due to the reduced lifetime, substantially increasing detectability.

Europium↗

Nanoleakage within the hybrid layer: a correlative FEISEM/TEM investigation.

The aim of this study was to compare the nanoleakage patterns of the resin-dentin interfaces of three dentin bonding systems at both TEM and field emission in lens SEM (FEI-SEM) levels. A standardized smear layer was created with 180-grit silicon carbide paper (SiC) on dentin disks obtained from 18 noncarious human third molars. Specimens were randomly divided into three groups and bonded with a two-step total etching adhesive (Single Bond, SB), a two-step, self-etching adhesive (Clearfil SE BOND, SEB), and a one-step, self-etching adhesive (XENO III, XEIII). Nanoleakage was evaluated by using an ammoniacal silver-nitrate solution. Specimens were processed for TEM and FEI-SEM observation. The TEM of SB revealed silver deposits in adhesive and hybrid layers (HL). High-magnification FEI-SEM micrographs clearly identified these deposits as spherical clusters mainly associated with nonembedded collagen fibrils. TEM and FEI-SEM examination of SEB revealed some clusters of silver deposits within porosities and small channels of the HL. Additional silver deposits were observed between the peritubular dentin walls and the resin tags. XEIII revealed very fine and diffuse silver grains throughout the entire HL. SEM visualization of nanoleakage at a high level of resolution has not been previously described. FEI-SEM technology supported the TEM visualization with three-dimensional morphological data of the relations between the HL constituents and nanoleakage. The results of the present study confirm the hypothesis that both total- and self-etch adhesives are not able to fully infiltrate the dentin substrate.

Acid Etching, Dental↗

Controllable growth of chains and grids from polyoxomolybdate building blocks linked by silver(I) dimers.

Molecular growth processes utilizing a beta-octamolybdate synthon and {Ag2} dimers are described and the directing influence of "encapsulating" cations and coordinating solvent is also demonstrated. The growth of two 1D chains, (nBu4N)2n[Ag2Mo8O26]n (1) and (nBu4N)2n[Ag2Mo8O26(CH3CN)2]n (2), is achieved when nBu4N+ ions are used, and the diameter of the chains can be expanded by the coordination of CH3CN solvent (2). The formation of a type of gridlike structure in which 1D chains are crossed-over each other in alternatively packed layers is achieved in DMSO as the solvent; DMSO acts as a linking group to give (nBu4N)2n[Ag2Mo8O26(dmso)2]n (3), which, similar to 1 and 2, still incorporates the Bu4N+ ions that exert an "encapsulating" influence. However, in (HDMF)n[Ag3(Mo8O26)(dmf)4]n (4) the relatively bulky Bu4N+ ions are exchanged for protonated DMF cations, thereby allowing the chains to condense to a 2D array. The building block concept is further enforced by the isolation of a "monomeric" unit (Ph4P)2[Ag2Mo8O26(dmso)4] (5), which is isolated when the Ph4P+ ions are so "encapsulating" as to prevent aggregation of the {Ag-Mo8-Ag} building blocks. The nature of the AgAg dimers in each of the compounds 1-4 is examined by DFT calculations and the interplay between these Ag-Ag interactions and the structure types is described.

Acetonitriles↗

Silver amplification of mercury sulfide and selenide: a histochemical method for light and electron microscopic localization of mercury in tissue.

A method for light and electron microscopic demonstration of mercury sulfides and mercury selenides in mammalian tissue is presented. Silver ions adhering to the surface of submicroscopic traces of mercury sulfides or selenides in the tissue are reduced to metallic silver by hydroquinone. Physical development thereupon renders deposits of mercury sulfides or mercury selenide visible as spheres of solid silver. Examples of localization of mercury in the central nervous system and various organs from animals exposed to mercury chloride or methyl mercury chloride with or without additional sodium selenide treatment are presented. Selenium treatment results in a considerable increase in the amount of mercury that can be made visible by silver amplification. After mercury chloride treatment, most of the mercury is localized in lysosomes and is only rarely seen in secretory granules. After simultaneous selenium treatment, mercury is also found in nuclei of proximal tubule cells in the kidney and in macrophages. The "sulfide-osmium" method for ultrastructural localization of mercury suggested by Silberberg, Lawrence, and Leider (Arch Environ Health 19:7, 1969) and the light microscopic method using a photographic emulsion suggested by Umeda, Saito, and Saito (Jpn J Exp Med 39:17, 1969) have been experimentally analyzed and commented on.

Animals↗

Dot-immunogold-silver staining in the diagnosis of cysticercosis.

Dot-immunogold-silver staining (Dot-IGSS) and Dot-ELISA were used, with Taenia solium cyst fluid antigen, to detect specific antibodies in the sera of patients with cysticercosis. All 40 confirmed cases of cysticercosis were found to be positive when tested by 2 methods. The average titer of the sera detected by Dot-IGSS was 1:27,470, which was significantly higher than that detected by Dot-ELISA. The false positive rates were 2% and 4% in 50 healthy controls for Dot-IGSS and Dot-ELISA, respectively, with a low titer of 1:20.

Antibodies, Helminth↗

Self-assembled monolayers of alkaneselenolates on (111) gold and silver.

Self-assembled monolayers (SAMs) formed from didodecyl diselenide (C12SeSeC12) and didodecyl selenide (C12SeC12) on (111) Au and Ag substrates were extensively characterized by several complementary techniques. C12SeSeC12 was found to form contamination-free, densely packed, and well-ordered C12Se SAMs on both substrates, whereas the adsorption of C12SeC12 occurred only on Au and resulted in the formation of a SAM-like C12SeC12 film with a low packing density and a conformational disorder. The properties of the C12Se SAMs were compared with those of dodecanethiolate (C12S) SAMs. The packing density, orientational order, and molecular inclination in C12Se/Au and C12S/Au were found to be very similar. In contrast, C12Se/Ag exhibited significantly lower packing density, a lower degree of the conformational and orientational order, and a larger molecular inclination than C12S/Ag. The results suggest a sp3 bonding configuration for the selenium atom on Au and Ag and indicate a larger corrugation of the headgroup-substrate binding energy surface in C12Se/Ag than in C12S/Ag.

Gold↗

Cu(I)-carbenoid- and Ag(I)-Lewis acid-catalyzed asymmetric intermolecular insertion of alpha-diazo compounds into N-H bonds.

Chiral Cu(I)-bisoxazoline- and Cu(I)-PN-complexes were found to catalyze the intermolecular insertion of alpha-diazo compounds into N-H bonds. The insertion reactions proceed with enantioselectivities of up to 28% ee for the different alpha-diazo acetates into one of the N-H bonds of different amines. Analogous chiral Ag(I) complexes were found to give higher enantioselectivities of up to 48% ee, however, lower yields were obtained. There are indications, that the Ag(I)-mediated reactions follow a different reaction mechanism compared to the Cu(I)-catalyzed insertions. It is demonstrated that different alpha-amino acid derivatives can be obtained via this approach in good yields and with low to moderate enantioselectivities. However, the results obtained are the highest asymmetric inductions obtained for an intermolecular N-H insertion via chiral carbene complexes or chiral Lewis acid catalysis.

Catalysis↗

Ultrastructural demonstration of a glycoproteinic surface coat in allergenic pollen grains by combined cetylpyridinium chloride precipitation and silver proteinate staining.

In allergenic birch pollen grains, highly watersoluble surface substances were precipitated by the cationic detergent cetylpyridinium chloride (CPC) during aqueous fixation. After processing the pollen for electron microscopy, ultrathin sections of pollen grains were subjected to the periodic acid - thiocarbohydrazide - silver proteinate (PA-TCH-SP) procedure according to Thiery (1967) for the detection of vicinal glycol groups. It was found that the material precipitated by CPC on the surface and within the exine cavities of the pollen wall strongly reacted with the PA-TCH-SP reagent thus indicating the presence of polysaccharides on the surface of birch pollen grains. In samples which had not been treated with the cationic detergent, PA-TCH-SP reactivity was reduced to thin linings on the surface and within the exine cavities. In both cases the exine proper did not stain whereas the intine showed moderate staining. Within the aperture region of the intine, PA-TCH-SP reactivity is preferably associated with fibrillar or reticular structures. The results are discussed with special reference to biochemical findings on allergenic birch pollen proteins.

Cetylpyridinium↗

Quantitative proteome analysis in benign thyroid nodular disease using the fluorescent ruthenium II tris(bathophenanthroline disulfonate) stain.

Thyroid tumorigenesis involves qualitative and quantitative changes in protein expression, which can be comprehensively studied by proteome analysis. However, one of the technical bottlenecks of proteomics remains a reliable, sensitive and inexpensive method for quantification of differentially expressed proteins. This is due to the limited linear range of most available protein stains, i.e. silver and Coomassie blue, and high costs of commercially available fluorescent stains. In this paper we describe our experience with a lab-made ruthenium based fluorescent stain (ruthenium II tris(bathophenanthroline disulfonate) (RuBPs)) to perform proteome analysis of nodular thyroid disease. We first compared the properties of RuBPs with two highly sensitive protein stains: (1) silver staining and (2) the commercially available fluorescent dye Sypro Ruby. We show that in addition to its highly sensitive staining capabilities similar to Sypro Ruby and silver (2 ng), RuBPs offers several advantages such as a broad dynamic range (similar to Sypro Ruby and 500 times broader than the dynamic range of silver stain), low costs ( 0.03 per gel) and excellent compatibility with mass spectrometry. We then applied the inexpensive RuBPs stain to 2D gels (pH 4-7) of four benign thyroid nodules and normal thyroid tissue. We were able to detect approximately 1800 protein spots/gel in our thyroid samples. Quantitative changes in protein expression levels of at least 20-42 proteins were noted in the benign nodules compared with the normal thyroid tissue of the same patient. Differentially expressed spots were further characterised by nano-LC-FTICR and MALDI-TOF mass spectrometry. In summary we demonstrate, that the novel fluorescent ruthenium II tris(bathophenanthroline disulfonate) stain is a highly sensitive, reliable and inexpensive tool for quantitative proteome analysis in thyroid nodular disease.

Dextrans↗

Metal-organic architectures of silver(I), cadmium(II), and copper(II) with a flexible tricarboxylate ligand.

Three novel metal-organic architectures, [Ag3(bta)].1.5H2O (1), [Cd3(bta)2(H2O)7].5H2O (2), and [Cu11(bta)6(Hbta)2(H2O)10].29H2O (3), were obtained by reactions of the corresponding metal salts with a flexible tripodal ligand, benzene-1,3,5-triacetic acid (H3bta), and their structures were determined by single-crystal X-ray diffraction studies. The results revealed that, in complexes 1 and 2, the carboxylate groups of the bta3- ligand adopted varied coordination modes to link metal atoms and further to form three-dimensional structures with open channels occupied by water molecules, while in complex 3, for the first time, the flexible H3bta acted as a secondary building unit to generate a novel nanometer-sized metallocage, which is composed of a Cu(II) paddle wheel (square secondary building units) and bta3-/Hbta2- organic links (triangular secondary building units). The photoluminescence properties of complexes 1 and 2 were investigated, and the results showed that 2 exhibited photoluminescence in the solid state at room temperature.

Acetates↗