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At least 613 records · Page 34Linked to original sources
PubMed1997

[Agranulocytosis after application of silver sulfadiazine in a 2-month old infant].

BACKGROUND: A granulocytosis associated with the use of silver sulfadiazine has been described in burn patients. This agranulocytosis may be due to either an allergic reaction or a bone marrow toxicity by silver sulfadiazine. CASE REPORT: A 1-month old baby was hospitalized in pediatric intensive care unit after a stage one repair of a tracheoesophegeal fistula. Gastroesophageal reflux and tracheomalacia appeared in the post operative period. When she was 2-months old, she developed a perineal erythema. A topical therapy was begun, with daily applications of silver sulfadiazine and ketoconazole. Five days later, agranulocytosis (granulocytes = 0.21 x 10(9).L-1) occurred. Silver sulfadiazine therapy was immediately stopped. Granulocyte count returned to normal over a few days. No other etiology than silver sulfadiazine could be found to explain agranulocytosis. The small surface of administration, the chronology of the events and the rapid correction of the disorders after silver sulfadiazine interruption argued for an immuno-allergic reaction to this drug. Medical problems were easily controlled and the patient recovered well. CONCLUSION: This event occurred when sulfadiazine was applied in a small cutaneous area in a young baby. This may be an argument for an allergic reaction; alternatively, it could be explained by an increased cutaneous absorption of a cytotoxic drug in younger people.

Agranulocytosis↗
PubMed1998

Activity of silver ions in different media.

A major problem in medicine is the large number of infections associated with implanted and indwelling devices. Silver coating of medical devices is believed to preserve infection resistance. Several in vitro and animal studies as well as clinical observations on silver-nylon, silver-intramedullary pins, silver-oxide-Foley catheters and silver-coated vascular protheses have been interpreted as successful for the prophylaxis of foreign-body infections. Nevertheless, these products have not been established in clinical use. In this study we have been able to present physico-chemical and pharmacological data as well as simple microbiological experiments explaining the reduced anti-microbial activity of silver-ions in some biological fluids.

Bacterial Adhesion↗
PubMed2002

A novel approach for the adsorption of iodine-125 on silver wire as matrix for brachytherapy source for the treatment of eye and prostate cancer.

The adsorption of iodine-125 on silver wire bits coated with palladium to be sealed in titanium capsules as brachytherapy sources was studied. A method was optimized to obtain quantitative adsorption of 125I on the palladium treated silver wires. A comparative evaluation of palladium coated and uncoated (bare) silver wires on the adsorption of 125I was made. While, the adsorption of bare silver wires showed low, inconsistent uptake (approximately 60%) of 125I with high leachability (approximately 4%), the Pd coated silver wires showed quantitative and consistent uptake of 125I (approximately 90%) and exhibited low leachability (0.01%). 125I adsorbed on Pd coated silver wires could be used as a matrix for the preparation of interstitial sources in eye and prostate cancer therapy.

Adsorption↗
PubMed2003

Rifampin and Triclosan but not silver is effective in preventing bacterial infection of vascular dacron graft material.

OBJECTIVES: To evaluate the efficacy of silver- or Triclosan-coated prosthetic material compared to Rifampin bonded Dacron concerning their resistance to infection following subcutaneous implantation and contamination with Staphylococcus aureus. DESIGN: Animal experimental study in mice. MATERIAL AND METHODS: Thirty-six C3H/HcN mice (Charles River Lab., Sulzfeld, Germany) with a weight between 24 and 27 g were randomised into six groups counting six animals each. Group I: control, gel-sealed dacron graft, group II: gel-sealed dacron graft and local contamination, group III: Intergard-Silver-prosthesis and contamination, group IV: silver/gel-sealed dacron prosthesis (test graft) and contamination, group V: Rifampin-bonded gel-sealed graft and contamination, group VI: Triclosan/collagen-coated dacron graft and contamination. Dacron graft material 0.8x1 cm was subcutaneously implanted in mice. Local contamination with 2x10(7)/0.2 ml S. aureus ATCC 25923 was carried out in groups II to VI. On day 14 the animals were killed and the grafts were explanted. The microscopic, histologic and microbiological evaluation of the graft material and the perigraft tissue was performed. RESULTS: In control group I no case of infection was detected. In group II, 6 of 6 animals showed infection. In group III (Intergard-Silver) and group IV (silver/gel-test graft) were 6 of 6, in group V (Rifampin) only 1 of 6 grafts and in group VI (Triclosan) 4 of 6 grafts were infected. The difference between the low rate of infection in group V (Rifampin) in comparison to the completely infected groups III and IV (Silver) as well as the control group II was significant. Treatment of grafts with Triclosan could prevent infection only in 1/3 of the cases in group IV. CONCLUSION: Silver coating failed to prevent graft infection material. A potential antimicrobial property was evident for Triclosan whereas Rifampin-bonded grafts exhibit a significantly reduced infection rate. Thus, silver-coated vascular grafts cannot ensure protection from vascular graft infection.

Animals↗
PubMed2003

Socially-induced changes in sodium regulation affect the uptake of water-borne copper and silver in the rainbow trout, Oncorhynchus mykiss.

Subordinate fish take up more copper during water-borne exposure than dominant fish and consequently display higher tissue burdens. The present study demonstrated a similar effect of social status on water-borne silver uptake. We evaluated whether differences in copper and silver accumulation between individuals could be due to differences in metabolic rate, internal concentrations of cortisol or sodium uptake rates. In the absence of social interaction, experimentally increased metabolic rates (via moderate exercise) and elevated whole body cortisol concentrations (via feeding of a cortisol-spiked diet) did not result in increased metal uptake. However, elimination of the difference in sodium uptake rates between dominant and subordinate fish by exposing them to a saturating level of water-borne sodium (50 mM) resulted in an elimination of copper uptake differences. No significant differences in sodium and silver uptake rates were seen between dominant and subordinate fish exposed to elevated silver concentrations. Therefore, it appears that socially-mediated differences in copper and silver accumulation are a result of differences in sodium uptake rates as both silver and copper are known to cross the gill epithelia via sodium transport pathways.

Animal Feed↗
PubMed1980

Treatment of allergic and vasomotor rhinitis by the local application of silver nitrate.

A new, simple and effective local treatment of allergic and vasomotor rhinitis is presented. Using 15 per cent silver nitrate, bilateral chemical cautery of the anterior part of the nasal septum and inferior turbinates has been carried out at weekly intervals on 1 to 5 occasions, in 41 cases. No distinction was made between allergic rhinitis and vasomotor rhinitis. 92.6 per cent of cases belonged to the age group of 11 to 50 years. There was a slight predominance of female over male patients in this study. Only those cases were selected who had sneezing as the presenting symptom, while 17 per cent of these patients also suffered from asthma. The eosinophil count in the blood was below 5 per cent in 73.2 per cent of cases, and was above 10 per cent in 9.8 per cent of cases. Eosinophils were present in the nasal secretions of of 66.6 per cent of patients. Intestinal parasites were detected in the stools of 19.5 per cent of cases. No significant quantity of methaemoglobin was detected in the blood of any patient. Silver nitrate was applied after topical anaesthesia with 4 per cent lignocaine solution. The majority of patients had 2 to 4 applications. 68.3 per cent of patients had good relief, particularly from sneezing and watering of the nose. If patients treated with only a single application of silver nitrate are excluded from the series, 79.4 per cent patients reported relief. Significantly, out of 7 cases who were suffering from allergic rhinitis as well as asthma, 57.1 per cent of cases had freedom from the asthma. Among 3 patients who had no relief with earlier intranasal hydrocortisone injections, 66.6 per cent cases had good relief with silver nitrate. One patient who had good relief from allergic rhinitis developed anosmia after this treatment and some patients experienced transient sneezing and rhinorrhoea after the application of silver nitrate. Long-term results are awaited and it is suggested that further studies are necessary regarding the number of applications, the interval between applications, the strength of the silver nitrate solution, and the possible use of other chemical or physical agents for this mode of treatment.

Administration, Topical↗
PubMed2005

Silver complexation and tandem mass spectrometry for differentiation of isomeric flavonoid diglycosides.

For detection and differentiation of isomeric flavonoids, electrospray ionization mass spectrometry is used to generate silver complexes of the type (Ag + flavonoid)+. Collisionally activated dissociation (CAD) of the resulting 1:1 silver/flavonoid complexes allows isomer differentiation of flavonoids. Eighteen flavonoid diglycosides constituting seven isomeric series are distinguishable from each other based on the CAD patterns of their silver complexes. Characteristic dissociation pathways allow identification of the site of glycosylation, the type of disaccharide (rutinose versus neohesperidose), and the type of aglycon (flavonol versus flavone versus flavanone). This silver complexation method is more universal than previous metal complexation methods, as intense silver complexes are observed even for flavonoids that lack the typical metal chelation sites. To demonstrate the feasibility of using silver complexation and tandem mass spectrometry to characterize flavonoids in complex mixtures, flavonoids extracted from grapefruit juice are separated by high-performance liquid chromatography and analyzed via a postcolumn complexation ESI-MS/MS strategy. Diagnostic fragmentation pathways of the silver complexes of the individual eluting flavonoids allow successful identification of the six flavonoids in the extract.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Geranium leaf assisted biosynthesis of silver nanoparticles.

Development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. In this paper, we report on the use of Geranium (Pelargonium graveolens) leaf extract in the extracellular synthesis of silver nanoparticles. On treating aqueous silver nitrate solution with geranium leaf extract, rapid reduction of the silver ions is observed leading to the formation of highly stable, crystalline silver nanoparticles in solution. Transmission electron microscopy analysis of the silver particles indicated that they ranged in size from 16 to 40 nm and were assembled in solution into quasilinear superstructures. The rate of reduction of the silver ions by the geranium leaf extract is faster than that observed by us in an earlier study using a fungus, Fusarium oxysporum, thus highlighting the possibility that nanoparticle biosynthesis methodologies will achieve rates of synthesis comparable to those of chemical methods. This study also represents an important advance in the use of plants over microorganisms in the biosynthesis of metal nanoparticles.

Chemical Precipitation↗
PubMed2006

Synthesis from caffeine of a mixed N-heterocyclic carbene-silver acetate complex active against resistant respiratory pathogens.

The bis(N-heterocyclic carbene) (NHC) silver complex, 3, with a methyl carbonate anion was formed from the reaction of the iodide salt of methylated caffeine, 1, with silver (I) oxide in methanol. Attempts to crystallize this complex from a mixture of common alcohols and ethyl acetate led to the formation of an NHC-silver acetate complex, 4. The more direct synthesis of 4 was accomplished by the in-situ deprotonation of 1 by silver acetate in methanol. Complex 4 demonstrated antimicrobial activity against numerous resistant respiratory pathogens from the lungs of cystic fibrosis (CF) patients including members of the Burkholderia cepacia complex that cause a high rate of mortality in patients with cystic fibrosis (CF). Application of this NHC silver complex to primary cultures of murine respiratory epithelial cells followed by microarray analysis showed minimal gene expression changes at the concentrations effective against respiratory pathogens. Furthermore, methylated caffeine without silver showed some antibacterial and antifungal activity.

Acetates↗
PubMed2005

Metal-enhanced fluoroimmunoassay on a silver film by vapor deposition.

We studied a fluoroimmunoassay using metal-enhanced fluorescence (MEF) detection on silver film generated by vapor deposition method. The morphology of the silver film was controlled through the thickness of the film. A silica layer was coated on the silver film to protect the film and separate the fluorophore from the metal surface. Rabbit immunoglobulin G (IgG) was adsorbed on the silica by physiosorption and then dye-labeled anti-rabbit IgG was bound to the immobilized rabbit IgG. It was observed that the fluorophore was quenched on a thin silver film (2 nm), enhanced on a thick film (>5 nm), and reached saturation (ca. 10 times enhancement) at 20 nm. The MEF was also dependent on the thickness of the silica with a maximum at 10 nm. The lowest lifetime was observed on the 20 nm silver film, which was consistent with the saturation of MEF. These results showed the properties of a silver film needed for a maximum increase of fluorescence intensity in a fluoroimmunoassay. Dependence of the MEF on the emission wavelength was also studied using different dye-labeled anti-rabbit IgGs.

Clinical Laboratory Techniques↗
PubMed2005

Influence of pinning effects on the electrochemical formation of silver patterns in agarose-containing sols and gels.

The formation of silver patterns via electrolysis from aqueous silver sulfate + x% w/v agarose sol and gel media, with and without supporting electrolyte, in a quasi-two-dimensional (2D) cylindrical cell at room temperature, is utilized as a reference system to investigate the complexity of pinning effects. From pattern morphology and electrochemical data, both delocalized and localized pinning in the bulk dominate the drift of the growth front, depending on the concentration of agarose in the heterogeneous media. Delocalized pinning results from mobile, small agarose aggregates at the growth front and from their accumulation by the front drift. For gels, localized pinning comes from their own percolated structure. A depinning/pinning transition is observed in going from sols to gels. The relative contribution of diffusion and advection in mass-transport-controlled silver electrodeposition depends on the plating bath composition. On the other hand, silver ion attachment to the cathode appears to be interfered with by some screening caused by weakly adsorbed, mobile agarose aggregates at the metal surface without slowing down the rate of the electron-transfer step at the cathode. Their relative contribution of a delocalized, localized pinning and screening effect to a great extent determines the morphology and transition in the growth mode of silver patterns in both media. The analysis of charge and current transients and the corresponding silver pattern morphologies for open and dense radial patterns is made. Results are qualitatively simulated with a novel, rather simple cellular automaton algorithm.

Electrochemistry↗
PubMed2006

Preparation and study of polyacryamide-stabilized silver nanoparticles through a one-pot process.

A one-pot route was illustrated to synthesize stable well-dispersed silver colloids stabilized by polyacrylamide on a large scale. Reduction of silver ions and polymerization of acrylamide occurred almost simultaneously in the absence of a commonly used reducing agent and initiator. A possible mechanism for the formation of silver nanoparticles with bimodal size distribution was proposed. The structure and composition of the obtained nanoparticles were characterized carefully. Furthermore, light scattering simulation and UV-vis absorption studies confirmed that the obtained colloids were the mixture of Ag and Ag2O nanoparticles. The presence of silver oxide layers on the nanoparticle surface should be responsible for the broadening of the surface plasmon band of silver nanoparticles. Ag2O layers could be added or removed from Ag nanoparticle surfaces by the addition of HNO3, HAc, or NaCl solution to the as-obtained silver colloids.

Acrylic Resins↗
PubMed2006

Self-assembly of silver nanoparticles: synthesis, stabilization, optical properties, and application in surface-enhanced Raman scattering.

Silver nanoparticle aggregates were synthesized in large scale using resorcinol under alkaline condition to obtain an assembly of silver clusters. Stable dispersion of the cluster in aqueous medium has been examined out of resorcinol-capped silver nanoparticle assemblies. The UV-vis spectroscopy during the particle evolution has been studied in detail. From the high-resolution TEM (HRTEM) image and XRD pattern it was confirmed that the particles are made of pure silver only. The capping action of resorcinol has been authenticated from the FTIR spectra. UV-vis spectroscopy and TEM images reveal that the temperature, effect of vibrational energy, heat shock, and time-dependent particle evolution have unique bearing on the stability and surface properties of the clusters. The concentrations of silver nitrate, resorcinol, and NaOH have important influence on the particle evolution and its size. TEM images incite us to examine the aggregates to capitulate surface-enhanced Raman scattering (SERS) to the single molecular level using crystal violet (CV) and cresyl fast violet (CFV) as molecular probes. The SERS intensity of CV increases with increasing the size of the silver aggregate.

Metal Nanoparticles↗
PubMed2006

Silver colloid nanoparticles: synthesis, characterization, and their antibacterial activity.

A one-step simple synthesis of silver colloid nanoparticles with controllable sizes is presented. In this synthesis, reduction of [Ag(NH(3))(2)](+) complex cation by four saccharides was performed. Four saccharides were used: two monosaccharides (glucose and galactose) and two disaccharides (maltose and lactose). The syntheses performed at various ammonia concentrations (0.005-0.20 mol L(-1)) and pH conditions (11.5-13.0) produced a wide range of particle sizes (25-450 nm) with narrow size distributions, especially at the lowest ammonia concentrations. The average size, size distribution, morphology, and structure of particles were determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), and UV/Visible absorption spectrophotometry. The influence of the saccharide structure (monosacharides versus disaccharides) on the size of silver particles is briefly discussed. The reduction of [Ag(NH(3))(2)](+) by maltose produced silver particles with a narrow size distribution with an average size of 25 nm, which showed high antimicrobial and bactericidal activity against Gram-positive and Gram-negative bacteria, including highly multiresistant strains such as methicillin-resistant Staphylococcus aureus. Antibacterial activity of silver nanoparticles was found to be dependent on the size of silver particles. A very low concentration of silver (as low as 1.69 mug/mL Ag) gave antibacterial performance.

Anti-Bacterial Agents↗
PubMed2004

Synthesis of aqueous Au core-Ag shell nanoparticles using tyrosine as a pH-dependent reducing agent and assembling phase-transferred silver nanoparticles at the air-water interface.

We demonstrate that the amino acid tyrosine is an excellent reducing agent under alkaline conditions and may be used to reduce Ag+ ions to synthesize stable silver nanoparticles in water. The tyrosine-reduced silver nanoparticles may be separated out as a powder that is readily redispersible in water. The silver ion reduction at high pH occurs due to ionization of the phenolic group in tyrosine that is then capable of reducing Ag+ ions and is in turn converted to a semi-quinone structure. These silver nanoparticles can easily be transferred to chloroform containing the cationic surfactant octadecylamine by an electrostatic complexation process. The now hydrophobic silver nanoparticles may be spread on the surface of water and assembled into highly ordered, linear superstructures that could be transferred as multilayers onto suitable supports by the versatile Langmuir-Blodgett technique. Further, tyrosine molecules bound to the surface of Au nanoparticles through amine groups in the amino acid may be used to selectively reduce silver ions at high pH on the surface of the Au nanoparticles, thus leading to a simple strategy for realizing phase-pure Au core-Ag shell nanostructures.

Air↗
PubMed1999

Effect of inflammatory stimuli on the silver staining pattern of the rat carotid endothelium.

Silver nitrate stains the intercellular junctions of the endothelium and other cytoplasmic or membrane components. Two protocols are described for the silver staining of rat carotid endothelium that exclude the use of pressurized fixatives and simplify the technique previously described for rat aorta. The entire surface of the carotid endothelium was examined and several parameters (stigmata, granularity, clustering of anionic sites, transversal lines, weakening of silver lines and leukocyte adhesion) were evaluated. We studied the pattern of silver staining in two situations: (1) endothelial activation and (2) neurogenic inflammation. Endothelial activation was produced by the intravenous administration of a proinflammatory albumin or polyinosinic acid. Both products cause a marked increase in leukocyte adhesion concomitant with a decrease in argyrophilia and a weakness or loss of silver lines. Neurogenic inflammation, which is mediated by substances released from sensory nerves, was induced by the intravenous administration of substance P or capsaicin. Both stimuli produced an increase in argyrophilia and weakness or loss of silver lines. Substance P caused a clustering of anionic sites, whereas this phenomenon was more discrete with capsaicin. Nearly 80% of all examined rats (controls and inflammatory stimuli treated) showed endothelial membrane disruptions formed by clusters of cells often in the shape of streaks aligned with the long axis of the vessel. The detection of these discontinuities is important, as loss of endothelial integrity is central in the initiation of pathological events.

Animals↗
PubMed2004

Fluorescence enhancements on silver colloid coated surfaces.

We observed a strong, more than 16-fold, enhancement of Texas Red-labeled BSA fluorescence emission when deposited on silver colloid coated surfaces (SCCS). The same labeled protein deposited on silver island films (SIFs) showed an approximate 8-fold fluorescence enhancement. The lifetimes of Texas Red-BSA fluorescence are significantly shorter on silvered surfaces than on uncoated quartz substrate indicating a strong change in radiative decay rate of the dyes. We also observed a 36-fold increased brightness of overlabeled fluorescein-HSA deposited on silver colloid coated surface. Stronger enhancement observed for overlabeled Fl-HSA protein indicates that presence of silver particles partially decreased self-quenching. Our results indicate that surfaces coated with silver colloids are valuable substrates for metal-enhanced fluorescence.

Algorithms↗
PubMed2001

Antimicrobial activity of silver nitrate against periodontal pathogens.

Metal ions were evaluated as potential antimicrobial agents suitable for local delivery in the oral cavity for the treatment of periodontitis. Silver nitrate, copper chloride, and zinc chloride were tested for antimicrobial activity in in vitro killing assays conducted in phosphate buffered saline with a series of oral bacteria including gram-negative periodontal pathogens and gram-positive streptococci. Copper and zinc salts failed to exhibit strong and consistent activity against periodontal pathogens. In contrast, silver at a concentration of 0.5 microg/mL produced a 3 log10 reduction in colony forming units (CFU)/mL or greater against all periodontal pathogens tested including Porphyromonas gingivalis, Prevotella intermedia, Prevotella denticola, Bacteroides forsythus, Fusobacterium nucleatum vincentii, Campylobacter gracilis, Campylobacter rectus, Eikenella corrodens, and Actinobacillus actinomycetemcomitans. In comparison, substantially higher concentrations of silver nitrate failed to kill oral streptococci. A silver nitrate concentration of 25 microg/mL produced log10 reductions in CFU/mL of 3.5-5 in killing assays performed in human serum against P. gingivalis, demonstrating the ability of silver to retain activity in a biological medium similar to that encountered in vivo in the periodontal pocket. These results identify silver nitrate, an antimicrobial that may possess advantages over traditional antibiotics, as a potential agent for controlled release local delivery in the oral cavity for the treatment of periodontitis.

Administration, Topical↗