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At least 577 records · Page 32Linked to original sources
PubMed1981

Silver staining of the neuronal nucleus in electron microscopy: nucleolar organization in supraoptic nuclei of the rat hypothalamus.

The present paper describes a simple, efficient method for silver impregnation of supraoptic nuclei of the rat hypothalamus using a modification of the ammoniacal silver technique of Cajal (1903). This procedure, involving a silver-developer sequence in tissue blocks prior to plastic embedding, permits the simultaneous study of Ag-impregnated supraoptic neurons at both light and electron microscopic levels. Visualization of secretory magnocellular neurons impregnated by this technique using the electron microscope reveals a good preservation of nuclear structures. A selective accumulation of silver grains was observed over heterochromatin clumps and nucleoli, which allows the identification of the nucleolar fibrillar centers and also the dense fibrillar component as the main areas involved in the silver reaction. The meaning of such a silver-distribution pattern is discussed in the light of recent ultrastructural and biochemical data.

Animals↗
PubMed1987

Effects of selenium on toxicity and ultrastructural localization of silver in cultured macrophages.

The effects of selenium on cellular toxicity and histochemical distribution of silver were examined in a cell culture system of mouse peritoneal macrophages. Selenium caused a significant delay in the appearance of coagulation necrosis induced by high silver concentrations and reduced the cytostatic effect of lower doses of silver when long-term toxicity was examined. Furthermore, selenium increased the amount of silver that could be visualized by autometallography. The additional silver made available for this histochemical demonstration was located in the cytosol as well as in lysosomes, the sole localization of silver when selenium was not administered.

Animals↗
PubMed1979

Cytological and histochemical studies on the mechanism of the selective silver staining of nucleolus organizer regions (NORs).

A new silver staining method is presented (Ag-II staining) providing a rapid and reproducible way to selective silver staining of nucleolus organizer regions (NORs). In comparison with other techniques, such as the Ag-AS method and the Ag-I method, factors influencing silver stainability are discussed. Histochemical studies on the nature of the NOR-specific silver precipitate were performed either by employing various pretreatments or by inhibiting the participation ("blocking") of the various proteins or protein compounds in the staining reaction. The results would seem to indicate that the interactions of silver-ions with the carboxyl groups of acidic proteins which are involved in the rRNA-transcription process are mainly responsible for the selective silver staining of NORs.

Animals↗
PubMed1995

A paint incorporating silver to control mixed biofilms containing Legionella pneumophila.

A three-stage chemostat containing a mixed consortium of microorganisms, including Legionella pneumophila, was used to determine the suitability of a silver-containing paint to control biofouling in water systems. The paint was efficient in controlling total surface colonisation by heterotrophic microorganisms and growth of the pathogen over a 2-week period. Biodiversity was limited in the presence of the silver paint and this was thought to help control L. pneumophila numbers. Glass control tiles suspended alongside the silver painted tiles also had reduced colonisation for the 2-week period, suggesting that low levels of silver leached from the paint surface. This loss of silver was confirmed since the inhibition of biofouling and inclusion of the pathogen was not maintained after the 2-week period. Although this paint was unsuitable for controlling biofouling over extended time periods, the data suggest that a reformulated paint or electrochemical method of introducing silver ions may be successful.

Biofilms↗
PubMed1983

Synthesis, physical properties and microbiological activities of more water soluble silver sulfadiazine derivatives.

In this study the preparation of five hydrophilic derivatives of sulfadiazine is reported. The common structural element in the compounds is the 2-sulfonamidopyrimidine moiety. Three of these compounds are suitable for the preparation of a photostable I: I silver compound. These silver compounds are five to ten times more water soluble than silver sulfadiazine. The IR, 1H- and 13C-NMR data point to a similar co-ordination of silver in these compounds as with silver sulfadiazine. The microbiological activity of these silver compounds against St. aureus is slightly lower.

Bacteria↗
PubMed1999

The Erlanger silver catheter: in vitro results for antimicrobial activity.

The antimicrobial activity of a silver-impregnated polymer catheter (the Erlanger silver catheter) was demonstrated by determining the microbial adhesion to the surface of the catheter and by measuring the rate of proliferation (viability) of microorganisms at this site. On the surface of a catheter impregnated with silver, according to previously described methods, the bacterial adhesion of Staphylococcus epidermidis is reduced by 28-40%. Bacterial proliferation on the surface of the catheter and biofilm production are also substantially reduced by the elution of free silver ions from the catheter matrix. Bacteriostatic and bactericidal activities can be determined. The antimicrobial efficacy of the silver catheter is not reduced by blood components. There is no loss in antimicrobial activity for weeks after preincubation in water or phosphate buffered saline. The antimicrobial activity depends on the extent of the active silver surface.

Animals↗
PubMed1999

Analysis of the acute cytotoxicity of the Erlanger silver catheter.

The Erlanger silver catheter consists of a new form of polyurethane, which contains finely dispersed metallic silver. The aim of this study was to establish the biocompatibility of this intravenous catheter by investigating the acute cytotoxicity of extracts from the Erlanger silver catheter on human fibroblasts and lymphocytes. Extracts of the Erlanger silver catheter were not cytotoxic for MRC-5 human fibroblasts nor for sensitized phytohemagglutinin (PHA)-stimulated human lymphocytes. The addition of silver powder of up to 2% by weight to the basic catheter polyurethane Tecothane led to no increase in acute cytotoxicity in comparison with untreated Tecothane. The Erlanger silver catheter is a new intravenous catheter with good biocompatibility.

Adult↗
PubMed1999

Biocompatibility testing of a new silver-impregnated catheter in vivo.

The purpose of this investigation was to compare the local effects of polyurethane (Tecothane) and silicone tubes with or without silver impregnation in rats. Bacterial colonization or infection of the exit site and/or tunnel were documented and interpreted. All tubes were placed subcutaneously or percutaneously in the neck of 41 Sprague-Dawley rats and guided beneath the dorsal muscles into the peritoneal cavity. The incidence of bacterial abscesses along the implanted tubes was evaluated daily. After 90 days, or earlier if sepsis developed, the animals were killed painlessly and various organs and tissues from the entry site and the catheter tunnel examined histologically. In the group where polyurethane tubes were placed percutaneously, there was no difference in the frequency of abscesses between silver-impregnated and non-impregnated tubes (5/6 with and 5/7 without silver). The only difference noted was in the group with percutaneously placed silicone tubes between those with and without silver. Abscesses only occurred in 2/4 animals in the silver group and in 5/5 animals in the control group. Histological examination showed no difference in either group between infectious and foreign body reactions. Silver particles in subcutaneous, muscle and peritoneal tissue could not be demonstrated.

Animals↗
PubMed2004

Evaluation of a triple-lumen central venous heparin-coated catheter versus a catheter coated with chlorhexidine and silver sulfadiazine in critically ill patients.

OBJECTIVE: To compare the incidence of catheter colonization and catheter-related bloodstream infections between heparin-coated catheters and those coated with a synergistic combination of chlorhexidine and silver sulfadiazine. DESIGN: Randomized, controlled clinical trial. SETTING: A 20-bed medical-surgical intensive care unit. PATIENTS: A total of 180 patients requiring the insertion of a trilumen central venous catheter. INTERVENTIONS. Patients were randomized to receive either a trilumen heparin or chlorhexidine and silver sulfadiazine-coated catheter. MEASUREMENTS: Catheter colonization was defined by a semiquantitative catheter tip culture yielding 15 or more colony-forming units or quantitative culture of 1,000 or more colony-forming units/ml. Catheter-related bloodstream infection as the isolation of the same microorganism from a peripheral blood culture and catheter tip. RESULTS: A total of 260 catheters were cultured. Out of 132 heparin-coated catheters, 29 were colonized and out of 128 chlorhexidine and silver sulfadiazine-coated catheters, 13 were colonized ( p=0.03), relative risk RR=2.16 (1.18-3.97). This represents an incidence of 23.5 and 11.5 episodes of catheter colonization per 1,000 catheter-days, respectively ( p=0.0059), RR=2.04 (1.05-3.84). Microorganisms isolated in catheter colonization from heparin-coated catheters were gram-positive cocci 23, gram-negative bacilli 7, and Candida spp 4. In chlorhexidine and silver sulfadiazine-coated catheters were gram-positive cocci 6 and gram-negative bacilli 11 ( p=0.009). The incidence of catheter-related bloodstream infections per 1,000 catheter-days was 3.24 in heparin-coated catheters and 2.6 in chlorhexidine and silver sulfadiazine-coated catheters ( p=0.79), RR=1.22 (0.27-5.43). CONCLUSIONS: In critically ill patients the use of trilumen central venous catheters coated with chlorhexidine and silver sulfadiazine reduced the risk of catheter colonization due to prevention of gram-positive cocci and Candida spp.

Adult↗
PubMed2002

Biocompatibility, encrustation and biodegradation of ofloxacine and silver nitrate coated poly-L-lactic acid stents in rabbit urethra.

The purpose of this study was to evaluate the biocompatibility, encrustation and biodegradation properties of silver nitrate and ofloxacine blended caprolactone-L-lactide copolymer coated self-reinforced poly-L-lactic acid (SR-PLLA) urospirals in situ in the male rabbit urethra. SR-PLLA urospirals coated with 10% by weight silver nitrate or 5% by weight ofloxacine blended copolymer or pure copolymer were inserted into the posterior urethra of 18 male rabbits. No prophylactic antibiotics were given. The animals were sacrificed 1 or 6 months after insertion. Urethral tissue reactions were histologically scored semiquantitavely and the appearence of the stents assessed using scanning electron microscopy. The biodegradation time of SR-PLLA stents was remarkably reduced by the caprolactone coating. Silver nitrate and ofloxacine blended copolymer coated urospirals caused less tissue reaction than urospirals with a pure copolymer coating. Silver nitrate coating effectively prevented biofilm formation and stent encrustation. Silver nitrate and ofloxacine blended copolymer coated SR-PLLA urospirals had good biocompatibility properties in rabbit urethra. In particular, coating with silver nitrate may provide possibilities of preventing bacterial adhesion to bioabsorbable stents.

Animals↗
PubMed1983

Ammoniacal silver staining of proteins: mechanism of glutaraldehyde enhancement.

When the conditions for detecting proteins by ammoniacal silver staining (B. R. Oakley, D. R. Kirsch, and N. R. Morris (1980) Anal. Biochem. 105, 361-363.) following gel electrophoresis were varied, it was noted that glutaraldehyde pretreatment was necessary for maximal staining, which could not be explained simply as the result of "fixation." Further studies indicated that glutaraldehyde enhancement of protein staining with this silver reagent was probably due to oxidation of the aldehyde groups by silver ions, resulting in metallic silver depositions within the gel which act as nucleation sites for additional metallic silver localization in the protein bands upon the addition of formaldehyde developer. This proposed mechanism is consistent with the Tollen's reaction, as well as some aspects of the photographic process. Consistent with this notion, silver-staining intensities are directly related to mole percentage lysine of various standard proteins.

Aldehydes↗
PubMed1991

Detecting proteins containing 3,4-dihydroxyphenylalanine by silver staining of polyacrylamide gels.

Proteins in which some or all of the tyrosine side chains are post-translationally modified to dihydroxyphenylalanine have been found in several invertebrate phyla. In this paper we describe the unusual silver-staining properties of these 3,4-dihydroxyphenylalanine (Dopa)-proteins in silver-stained polyacrylamide gels. Our evidence suggests that the rapid silver staining of these proteins is due to the 3,4-dihydroxyphenol ring which is a highly effective reducing agent in the alkaline development conditions used in the final step of most silver-staining procedures. Normal proteins comprising the standard 20 amino acids and tyrosine on its own, do not reduce silver under these conditions. Pretreatment of the gels with acid-dichromate solutions abrogates the rapid staining of the Dopa-proteins. This rapid silver-staining technique will facilitate the rapid screening of many additional organisms for Dopa-proteins using sodium dodecyl sulfate gels and small amounts of tissue.

Animals↗
PubMed1996

The determination of silver in whole blood and its application to biological monitoring of occupationally exposed groups.

A sensitive and rapid technique for directly measuring silver in blood, using electrothermal atomization atomic absorption spectrophotometry (ETAAS) is described. The method can be used to analyse precisely up to 40 blood samples a day in duplicate. Well-mixed, whole blood samples, collected in EDTA, were diluted 1 + 4 with a diluent containing 40 g l.-1 ammonium dihydrogen orthophosphate and 0.5 ml l.-1 Triton X-100. Aliquots of diluted blood were then analysed by ETAAS using wall atomization with a pyrolytically coated tube. The coefficient of variation for within-run precision was 4.55% at 10 micrograms 1.-1 and 5% at 25 micrograms 1.-1 Between-run variation, it was 4.1% at 25 micrograms l.-1 The analytical recovery for the method was 98% +/- 3% at both 8 and 30 micrograms 1. -1 The detection limit of the method was 0.1 microgram 1. -1, which was sufficiently sensitive to distinguish exposed from non-exposed individuals. Blood silver levels in unexposed subjects were found to be between < 0.1 and 0.2 micrograms 1. -1. Blood silver levels were determined in 98 occupationally exposed workers involved in bullion production, cutlery manufacture, chemical manufacture, jewelery production and silver reclamation. Blood silver levels ranged from 0.1 to 23 micrograms 1.-1, with some of the highest levels found in silver reclaimers.

Environmental Monitoring↗
PubMed1984

Ultrastructural localization of exogenous silver in the anterior pituitary gland of the rat.

Silver accumulations in the anterior pituitary of argyric rats were demonstrated using a histochemical method that visualizes minute traces of the metal. Silver was localized intra- and extracellularly throughout the anterior pituitary. Intracellular deposits were found within the lysosomes of somatotrophs and gonadotrophs. Extracellularly, the grains were located in basal laminae of portal veins and sinusoidal capillaries and in the membrane separating the anterior pituitary and part intermedia. The amount of deposited silver was dependent upon the dose of silver administered. Increasing the dose of silver lactate from 10 to 30 mg resulted in increased deposition, whereas a further increase to 60 mg did not alter the amount of silver deposited.

Animals↗
PubMed1984

Further evidence that phosphoprotein C23 (110 kD/pI 5.1) is the nucleolar silver staining protein.

Previously we demonstrated a similar distribution between nucleolar organizing region-(NOR)-specific silver staining and localization of nucleolar phosphoprotein C23 (MW 110 kD/pI 5.1) [1, 2]. We now report that under fixation conditions which allow for antibody binding and subsequent silver staining, monoclonal antibody against protein C23 blocks NOR silver staining as well as silver staining in interphase nucleoli. Monoclonal antibody against nucleolar phosphoprotein B23 (MW 37 kD/pI 5.1) did not block silver staining in either NORs or interphase nucleoli. These, along with earlier observations, provide evidence that nucleolar phosphoprotein C23 is the major silver staining protein of the nucleolus and that it is directly or indirectly associated with rDNA.

Animals↗
PubMed1984

Silver-plated dies. Part I: Platability of impression materials.

The purpose of this study were to determine the acceptability of silver-plated dies made from representative brands of impression material from each of the four groups of elastomers and to determine the time required for initial plating of dies. Permlastic and Impregum , each previously shown to produce consistent silver-plated dies, were used for comparison. Representatives from the condensation-reaction and addition-reaction ( polyvinylsiloxanes ) silicones groups were tested until satisfactory materials were selected. Citricon and Xantopren - Optosil were tested in the former group and President and Reprosil in the latter. Conclusions include the following: All materials were flash-plated in 10 minutes or less. Acceptable silver-plated dies were obtained from Permlastic and Impregum . Acceptable silver-plated dies were obtained from condensation-reaction silicones with Xantopren - Optosil . From the polyvinylsiloxane group, Reprosil plated more consistently than President. Both produce acceptable dies. The technique modification studied was not effective for Citricon and President. The surface quality of silver-plated dies and the consistency of plating varies with materials. Individual impression materials should be tested prior to their routine clinical use with silver-plating procedures.

Dental Casting Technique↗
PubMed1988

Control of prosthetic bacterial infection: evaluation of an easily incorporated, tightly bound, silver antibiotic PTFE graft.

Despite the use of prophylactic antibiotics in vascular surgery, prosthetic infection rate remains 2-5%. Antibiotics bound to vascular prostheses can control experimentally induced infection but prolonged antibacterial activity has not been achieved. This study evaluates the in vivo efficacy and antibiotic retention of an easily prepared silver-antibiotic prosthesis. Prostheses were prepared by combining silver with oxacillin or amikacin using an organic solvent. After evaporation of the solvent, the graft was left impregnated with the antibiotic complex. In vivo retention studies were performed by implanting PTFE 110Ag-oxacillin prostheses in four canine abdominal aortas. When prostheses were explanted at 1 week, mean antibiotic retention was found to be 20% of original activity, higher than the mean inhibitory concentration for Staphylococcus aureus. In three groups of five dogs, 20 X 7-mm prostheses of PTFE alone, PTFE silver-oxacillin, or PTFE silver-amikacin were implanted in the abdominal aorta and the grafts were inoculated with 10(7) S. aureus of a known bacteriophage type, in a closed retroperitoneal pocket. The animals were sacrificed at 1 week and the prostheses were excised for quantitative bacterial culture. PFTE silver-oxacillin, and PTFE silver-amikacin prostheses had 1.7 X 10(2) and 2.0 X 10(2) colonies, respectively, significantly less (P less than 0.05) than controls (1.3 X 10(6) colonies). These data suggest that antibiotic prostheses can be easily prepared without binding agents. They retain the bound antibiotic for a prolonged period and are effective in reducing graft infection in a stringent direct contamination model.

Amikacin↗
PubMed1996

In vitro antimicrobial efficacy of silver iontophoretic catheter.

A silver iontophoretic catheter was designed consisting of two silver wires connected to an electric power source and disposed in a parallel and helical manner around the proximal subcutaneous segment of a silicone catheter. In an in vitro tunnelled bridge model the silver iontophoretic catheter prevented the migration of Staphylococcus epidermidis from the highly contaminated hub to the sterile tip over a 40-d period. The silver impregnated cuff and electrically charged wires made of aluminium or iron delayed migration for only 72 h. A modified Kirby-Bauer technique, used to test the inhibitory activity of antimicrobial catheters, showed that the silver iontophoretic catheter has a broad spectrum inhibitory activity against Gram-positive bacteria, Gram-negative bacteria and Candida albicans. The silver iontophoretic catheter provides a long-term electrochemical barrier against the migration of organisms from the external contaminated environment into the sterile intravascular compartment.

Catheterization↗