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At least 37 records · Page 2Linked to original sources
PubMed1972

Developing elastic tissue. An electron microscopic study.

Electron microscopic identification of elastic tissue in normal and disease states has been uncertain due to the lack of a specific electron-dense stain. Recently we introduced a silver porphyrin electron microscopic stain (silver tetraphenylporphine sulfonate) for the identification of adult elastic tissue. This stain has now been employed to study the development of elastic tissue with the aim that new and old elastica can be differentiated at the electron microscopic level. Present observations showed that developing elastica consisted of two distinct morphologic components. Each portion exhibited different staining properties with the silver porphyrin and lead citrate. One component was fibrous and the other amorphous. The fibrous component stained with lead citrate while the amorphous stained with the silver porphyrin. The fibrous component was the first to appear; the amorphous portion appeared later in development and was formed within the fibrous matrix. Mature elastic tissue was devoid of the fibrous component. Based upon the morphologic appearance and staining properties, one can now differentiate between newly formed elastic tissue and the existing one in various disease states.

Animals↗
PubMed1992

Silver staining two types of meiotic nodules.

We have developed a reliable method for silver staining nodules on synaptonemal complexes (SCs) of tomato (Lycopersicon esculentum). This technique involves hypotonically bursting primary microsporocytes, fixing SC spreads with paraformaldehyde, and incubating the spreads at 40 degrees C in a 33% aqueous silver nitrate solution covered with nylon mesh. When tomato SCs were stained by this method, nodules were observed with the same distribution and frequency as nodules stained with uranyl acetate and lead citrate. Incubation in silver nitrate at higher temperatures caused the loss of some or all nodules. The pattern of loss suggests that two types of nodules coexist during late zygonema and early pachynema and that one type becomes the late nodules of mid-pachynema through early diplonema.

Meiosis↗
PubMed2006

A simple method to synthesize triangular silver nanoparticles by light irradiation.

We describe a simple method to synthesize triangular silver nanoparticles by photoreducing the silver ions by citrate. A noteworthy difference of the present method as compared with the previous photo-induced methods is that good shape control over the nanoparticles can be realized in the absence of soft templates or polymer directing agents. The formation process of the silver nanoparticles was investigated by UV-vis spectroscopy and transmission electron microscopy (TEM). It was found that the concentration of reactant plays important role in the morphology control of produced silver nanoparticles. As one of the applications of these nanoparticles, they were used as surface-enhanced Raman scattering substrates and 1,4-bis[2-(4-pyridyl)ethenyl]-benzene (BVPP) was used as a Raman probe to evaluate the enhancement ability of the triangular silver nanoparticles.

Chemistry↗
PubMed2004

Dynamics of the interaction forces at the silver/solution interface during amine adsorption.

The forces of interaction between a silver-coated particle and a flat silver surface in an aqueous medium were measured in the presence of a series of organic amines of varying concentrations. Atomic force microscopy (AFM) was used to quantify the replacement rate of adsorbed citrate molecules on the silver surfaces by a variety of amines, under conditions where the time scale of the amine adsorption was significantly slower than the time scale of the AFM measurements. The decay length of the electrostatic double-layer interaction between the silver surfaces was found to be time independent; thus, the change in surface change density (determined from the interaction forces) was used to quantify the replacement rate of adsorbed citrate by amine. In the absence of amine, the interaction force between the silver surfaces exhibited evidence of a multilayer structure of adsorbed citrate molecules on each silver surface. Upon addition of the amine, a decrease in the interaction force was always observed, where the dynamics of the force were dependent on both concentration and the molecular structure of the amine. These results are discussed with respect to formation of colloidal particles in synthesis routes where particle aggregation has a significant impact on the control of particle morphology and size.

Journal Article↗
PubMed2005

Interfacing capillary electrophoresis and surface-enhanced resonance Raman spectroscopy for the determination of dye compounds.

The at-line coupling of capillary electrophoresis (CE) and surface-enhanced resonance Raman spectroscopy (SERRS) was optimized for the separation and subsequent spectroscopic identification of charged analytes (dye compounds). Raman spectra were recorded following deposition of the electropherogram onto a moving substrate. To this end a new interface was developed using a stainless steel needle as a (grounded) cathode. The outlet end of the CE capillary was inserted into this metal needle; CE buffer touching the needle tip served as the electrical connection for the CE separation. A translation table was used to move the TLC plate at a constant speed during the deposition. The distance between the tip of the fused silica column and the TLC plate was kept as small as possible in order to establish a constant bridge-flow, while avoiding direct contact. The dyes Basic Red 9 (BR9), Acid Orange 7 (AO7) and Food Yellow 3 (FY3) were used as test compounds. After CE separation in a 20 mM borate buffer at pH 10, after deposition, concentrated silver colloid was added to each analyte spot, followed by irradiation with 514.5 nm light from an argon ion laser to record the SERRS signal using a Raman microscope. Different types of silver colloids were tested: Lee-Meisel type (citrate), borate, and gold-coated silver. BR9 (positively charged) gave much more intense SERRS spectra than the two negatively charged dyes. For BR9 and AO7 the citrate-coated Lee-Meisel colloid yielded the most intense SERRS spectra. The CE-SERRS system was used to separate and detect the negatively charged dyes. Silver colloid and nitric acid (to improve adsorption) were added post-deposition. Even though their chemical structures are very similar, AO7 and FY3 could be readily distinguished based on their SERRS spectra. The limits of detection (S/N = 3) of the CE-SERRS system ranged from 6.7 x 10(-5) M (2.6 x 10(-12) mol injected) for FY3 down to 1.8 x 10(-6) M (7.0 x 10(-14) mol injected) for BR9.

Journal Article↗
PubMed2006

Citrate-assisted synthesis of prickly nickel microwires and their surface modification with silver.

A new type of prickly nickel microwires assembled by thornlike nanocrystals was fabricated through a simple chemical reduction route with the assistance of citrate. Thus-prepared nickel wires were subsequently morphology-retained modified with a thin silver shell via transmetallation. Compared with the uncoated sample, the Ni(core)-Ag(shell) wires exhibited much-enhanced oxidation resistance, slightly changed magnetic properties and stark different catalysis for the creation of carbon particles in pyrolyzing acetone.

Letter↗
PubMed2003

Gastrointestinal and systemic uptake of bismuth in mice after oral exposure.

Bismuth compounds have been used in medicine for more than 200 years. In recent years, bismuth has gained renewed interest as a remedy for eradication of gastrointestinal pathogens, especially Helicobacter pylori. In this study we describe the anatomical distribution of bismuth in the gastrointestinal tract and other organs after oral exposure in a mouse model. After exposure of the experimental animals to ranitidine bismuth citrate or bismuth citrate, we used the autometallographic silver enhancement technique to demonstrate the presence of bismuth in tissue samples from the gastrointestinal tract, liver, spleen, thymus, kidney and lymph nodes. We exposed cultured murine peritoneal macrophages to bismuth citrate and examined the bismuth accumulation over time. We found that in the mouse bismuth is absorbed systemically after a single dose of either compound, ranitidine bismuth more easily than bismuth citrate. Uptake could be shown in the stomach, duodenum, ileum and kidney for hours after exposure. Weeks after the exposure, deposits of bismuth were found in lymph nodes, liver, spleen and kidney as well as in macrophages in the gastrointestinal lamina propria. At the subcellular level, bismuth was found exclusively in lysosomes, primarily in macrophages and dendritic cells. Subsequent analyses of macrophage cultures showed lysosomal accumulations to be time and dose dependent.

Absorption↗
PubMed1991

Staining plant cells with silver. I. The salt-nylon technique.

A technique is described for selectively silver staining nucleoli, active nucleolus organizers, nucleolar material attached to chromosomes, kinetochores, synaptonemal complexes, and chromosome cores in plant cells. The technique, called salt-nylon silver staining, involves spreading cells on glass slides, treating the cells with a solution of saline sodium citrate, and incubating the cells in a silver nitrate solution covered with nylon screen. Selected variables important for achieving reliable silver staining are considered.

Allium↗
PubMed1976

Morphology and histochemistry of the adrenal medulla. I. Various types of primary catecholamine-storing cells in the mouse adrenal medulla.

Semithin sections (Araldite) of mouse adreno-medullary tissue were examined in the light microscope after perfusion fixation with glutaraldehyde, glutaraldehyde/formaldehyde or after freeze-drying followed by a treatment with hot formaldehyde gas. The following methods were employed: (i) aldehyde-induced fluorescence of catecholamines, (ii) Schmorl's ferric ferricyanide reaction, (iii) argentaffin reaction, and (iiii) staining with alkaline lead citrate followed by Timm's silver sulphide reaction. The correspondence of results obtained by the various methods was proven in consecutive sections or by successively applying different methods to identical sections. Four types of primary catecholamine-storing cells were identified. NA1 cells contain cytoplasmic granules up to 0.3 mum in diameter which stain black with ammoniacal silver and display a bright white to yellow fluorescence. NA2 cells show smaller cytoplasmic granules which stain brown with the argentaffin method and give white catecholamine fluorescence. NA3 cells appear yellow-earth after applying the argentaffin reaction and show greenish fluorescence. NA4 cells are hardly identified in the light microscope. These cells are significantly smaller than the above mentioned cells and characterized by a high nucleo-cytoplasmic ratio. They become straw coloured with ammoniacal silver and show greenish fluorescence. The argentaffin reaction was also used to identify these cells in semithin sections of glutaraldehyde/osmium tetroxide fixed material. The fine structure of the various noradrenalin-storing cells was studied in consecutive thin sections. NA1 cells were found to contain two populations of granules, the larger ones measuring between 300 and 350 nm, the smaller ones about 175 nm. The granules in NA2 cells correspond to this latter population (175 nm). NA3 cells contain an uniform granule population with a main diameter of 120 nm. The smallest granules are seen in NA4 cells being in the dimension of 80 nm. Granules in NA1 and NA2 cells show uniformly high density, whereas those in NA3 and NA4 cells display cores of varying density. Granules with moderately dense cores in NA3 and NA4 cells may represent partially emptied sites of noradrenalin storage or dopamin containing particles.

Adrenal Medulla↗
PubMed1993

Ultrastructural morphology, cytochemistry, and morphometry of eosinophil granules in Chédiak-Higashi syndrome.

Lysosomal enlargement in Chédiak-Higashi Syndrome (CHS) occurs to varying degrees in different cell types and has provided insight into the pathophysiology of lysosomal granules. This study was undertaken to determine the extent of involvement of eosinophil crystalloid granules (CGs) and smaller non-crystalloid granules (NCGs) in giant granule formation. Eosinophils from two CHS patients were evaluated after glutaraldehyde fixation and staining for morphologic examination, peroxidase, and complex carbohydrate using uranyl acetate-lead citrate, diaminobenzidine-lead citrate, and periodate-thiocarbohydrazide-silver proteinate (PA-TCH-SP) methods, respectively. Although many CGs appeared normal in shape and size, several CGs appeared enlarged and a few measured over 5 microns in diameter, consistent with giant granule formation in CHS. These giant granules either occasionally contained a single large crystalloid or, more frequently, contained numerous normal-size crystalloids. Enlargement of granules was also observed in some precursor CGs of bone marrow early eosinophils, indicating that giant granule formation was initiated during granule genesis. Almost all NCGs in late eosinophils were small granules and stained strongly with PA-TCH-SP in contrast to CGs. Most, but not all small granules were peroxidase-positive in eosinophil precursors, whereas the percentage of peroxidase-negative small granules increased in late eosinophils. This indicated the presence of at least two small granule populations. Morphometric studies indicated CHS selectively involved CGs and demonstrated that neither the average size nor numbers of NCGs were significantly different from normal eosinophils. Thus, these studies indicate that CHS selectively involves CGs, and demonstrate preservation of normal granule size and heterogeneity for NCGs in late eosinophils. These observations suggest that the underlying CHS pathophysiology does not involve all lysosomal subpopulations.

Carbohydrate Metabolism↗
PubMed1990

Degradation of metal-labeled collagen implants: ultrastructural and X-ray microanalysis.

Three different metal salts, silver nitrate, uranyl acetate and lead citrate, are mixed with a collagen gel to produce 3 metal/collagen sponges. These sponges were implanted subcutaneously in the rat and samples harvested after 5 days of implantation. TEM observation shows that sponges are degraded and digested by macrophages, polymorphonuclear cells (PMN) and fibroblasts. We have observed that the location of the precipitates differs according to the metal added to the collagen. Lead precipitates stay longer on the collagen mesh while silver precipitates, after 5 days, are soon digested and are found in phagosomes of macrophages. Uranium precipitates are digested with the collagen and uranium/collagen associated pictures are seen in phagolysosomes. Metal precipitates accumulated in phagolysosomes of macrophagic cells are recognized by X-ray microanalysis. The degradation process of implanted collagen is discussed.

Animals↗
PubMed2004

Silver-colloid-nucleated cytochrome c superstructures encapsulated in silica nanoarchitectures.

We recently discovered that self-organized superstructures of the heme protein cytochrome c (cyt. c) are nucleated in buffer by gold nanoparticles. The protein molecules within the superstructure survive both silica sol-gel encapsulation and drying from supercritical carbon dioxide to form air-filled biocomposite aerogels that exhibit gas-phase binding activity for nitric oxide. In this investigation, we report that viable proteins are present in biocomposite aerogels when the nucleating metal nanoparticle is silver rather than gold. Silver colloids were synthesized via reduction of an aqueous solution of Ag+ using either citrate or borohydride reductants. As determined by transmission electron microscopy and UV-visible absorption spectroscopy, the silver nanoparticles vary in size and shape depending on the synthetic route, which affects the fraction of cyt. c that survives the processing necessary to form a biocomposite aerogel. Silver colloids synthesized via the citrate preparation are polydisperse, with sizes ranging from 1 to 100 nm, and lead to low cyt. c viability in the dried bioaerogels (approximately 15%). Protein superstructures nucleated at approximately 10-nm Ag colloids prepared via the borohydride route, including citrate stabilization of the borohydride-reduced metal, retain significant protein viability within the bioaerogels (approximately 45%).

Chemical Phenomena↗
PubMed1987

Solid-state esterification of codeine phosphate by the acid constituent of effervescent tablets.

Codeine phosphate in a paracetamol:codeine effervescent tablet was found to react at room temperature and 37 degrees C with the citric acid constituent to form citrate esters of codeine. The esterification was confirmed in a solid-state reaction at elevated temperature. The structures of the three possible monosubstituted esters (1-3) were elucidated from spectroscopic data (nuclear magnetic resonance and mass spectrometry) and by selective hydrolysis of the dimethyl esters to give symmetrical and asymmetrical dimethyl citrates. In the degradation reaction, formation of the symmetrically substituted citrate ester of codeine, 1, was found to predominate. Tartaric acid, which can be used in effervescent tablet formulations, was also found to give an ester with codeine phosphate in a similar nonsolvolytic reaction. A liquid chromatographic method was developed for the separation of the citrate esters of codeine.

Chemical Phenomena↗
PubMed1983

Citrate utilization by Escherichia coli: plasmid- and chromosome-encoded systems.

Citrate utilization plasmids have previously been identified in atypical Escherichia coli isolates. A different citrate-utilizing (Cit+) variant of E. coli K-12 arose as a consequence of two chromosomal mutations (B. G. Hall, J. Bacteriol. 151:269-273, 1982). The processes controlling the transport of citrate in both a Cit+ chromosomal mutant and a Cit+ plasmid system were studied. Both systems were found to be inducible in growth experiments. In transport assays with whole cells, citrate-grown cells accumulated [1,5-14C]citrate at two to three times the rate of uninduced cells. Only the Vmax was affected by induction, and the Km for whole cells remained at 67 microM citrate for the chromosomal strain and 120 microM citrate for the plasmid-conferred system. There was no detectable accumulation of radioactivity with [6-14C]citrate, because of rapid metabolism and the release of 14CO2. Energy-dependent citrate transport was found with membrane vesicles obtained from both the chromosome-conferred and the plasmid Cit+ systems. The vesicle systems were inhibited by valinomycin and carbonyl cyanide m-chloro-phenylhydrazone but not by nigericin and monensin. In contrast to whole cells, the vesicle systems were resistant to Hg2+ and showed identical kinetics with [1,5-14C]citrate and [6-14C]citrate. H+ appeared to be important for citrate transport in whole cells and membranes. Monovalent cations such as Na+ and K+, divalent cations such as Mg2+ and Mn2+, and anions such as PO4(3-), SO4(2-), and NO3- were not required. The two systems differed in inhibition by citrate analogs.

Aconitic Acid↗
PubMed1981

Binding of glycosomes to endoplasmic reticulum and to intermediate filaments in cardiac conduction fibers.

Canine cardiac conduction fibers were fixed with glutaraldehyde, postfixed with OsO4 and treated en bloc with uranyl acetate. Ultrathin sections were stained sequentially by periodic acid-thiosemicarbazide-silver proteinate, for glycogen, and by uranyl acetate and lead citrate, for protein. Glycosomes (organelles composed of cardiac conduction fibers were fixed with glutaraldehyde, postfixed with OsO4 and treated en bloc with uranyl acetate. Ultrathin sections were stained sequentially by periodic acid-thiosemicarbazide-silver proteinate, for glycogen, and by uranyl acetate and lead citrate, for protein. Glycosomes (organelles composed of cardiac conduction fibers were fixed with glutaraldehyde, postfixed with OsO4 and treated en bloc with uranyl acetate. Ultrathin sections were stained sequentially by periodic acid-thiosemicarbazide-silver proteinate, for glycogen, and by uranyl acetate and lead citrate, for protein. Glycosomes (organelles composed of glycogen and protein) were found attached to membranes of endoplasmic reticulum (ER) and to intermediate filaments (IF). The bound glycosomes retained their integrity after treatment of tissue en block with uranyl acetate, a procedure that destroyed free glycosomes in the same cell. the coincident distributions of ER and IF and their association with glycosomes suggests a functional relation between there three components.

Acids↗
PubMed2005

Shape-controlled synthesis of metal nanostructures: the case of silver.

The concept of shape-controlled synthesis is discussed by investigating the growth mechanisms for silver nanocubes, nanowires, and nanospheres produced through a polymer-mediated polyol process. Experimental parameters, such as the concentration of AgNO(3) (the precursor to silver), the molar ratio between poly(vinylpyrrolidone) (PVP, the capping agent) and AgNO(3), and the strength of chemical interaction between PVP and various crystallographic planes of silver, were found to determine the crystallinity of seeds (e.g., single crystal versus decahedral multiply twinned particles). In turn, the crystallinity of a seed and the extent of the PVP coverage on the seed were both instrumental in controlling the morphology of final product. The ability to generate silver nanostructures with well-defined morphologies provides a great opportunity to experimentally and systematically study the relationship between their properties and geometric shapes.

Citrates↗