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PubMed1986

Inhibitory effects of electrically activated silver material on cutaneous wound bacteria.

Silver has had a widespread application in the care of burn wounds and chronic skin ulcers. The in vitro evaluation of unbound ionic silver is reported in this study. A comparison is made between silver-coated fabric alone and the fabric acting under direct electric current anodization. A variety of commonly found predominant skin pathogens were tested in this comparative study. Our studies confirm previous reports demonstrating an effective penetration of the silver ion and its local antibacterial action. Accurate measurements of the bacteria-free "clear zones" surrounding the electrically activated silver-coated fabric showed these to be significantly larger than those of the silver fabric without electric stimulation. This method affords another option in the use of silver for its antibacterial property, i.e., by iontophoresis. Its potential clinical use awaits further in vivo trials.

Anti-Bacterial Agents↗
PubMed2004

Is povidone iodine an alternative to silver nitrate for renal pelvic instillation sclerotherapy in chyluria?

OBJECTIVE: To compare the efficacy and toxicity of 1% silver nitrate, 0.2% povidone iodine and 50% dextrose in renal pelvic instillation sclerotherapy (RPIS) for chyluria. PATIENTS AND METHODS: In a prospective randomized comparative study from January 1999 to June 2003, 106 patients (61 males and 45 females; mean age 36 years, sd 12, range 14-65) were randomized to receive 1% silver nitrate, 0.2% povidone iodine or 50% dextrose as RPIS. In all, nine doses were given at 8-h intervals, and patients followed at 6 weeks and then at 3-monthly intervals. Patients with 'persistence' or 'recurrence' of chyluria were treated with second course of RPIS using same sclerosant. RESULTS: The dextrose treatment was discontinued at mid-term because of poor success (one of 21 patients, P < 0.001). Of 85 patients, 44 received silver nitrate and 41 povidone iodine; both groups were well-matched and the mean follow-up was 28.4 and 23.3 months, respectively. 'Immediate clearance' was recorded in 91% and 98%, and recurrence in 21% and 22% of patients after the first course of RPIS, after silver nitrate and povidone, respectively; Kaplan-Meier estimates of 'disease-free duration' in the two groups (23.6 vs 20.1 months) were also similar (P = 0.7906). The cumulative success rate after two courses of RPIS was 82% (silver nitrate) and 83% (povidone; P = 1.0). Five (11%) patients in the silver nitrate and one (2%) in the povidone group had significant flank pain during treatment. CONCLUSIONS: Povidone iodine 0.2% is as effective for RPIS as 1% silver nitrate.

Adolescent↗
PubMed2004

Use of aqueous silver to enhance inactivation of coliphage MS-2 by UV disinfection.

A synergistic effect between silver and UV radiation has been observed that can appreciably enhance the effectiveness of UV radiation for inactivation of viruses. At a fluence of ca. 40 mJ/cm(2), the synergistic effect between silver and UV was observed at silver concentrations as low as 10 microg/liter (P < 0.0615). At the same fluence, an MS-2 inactivation of ca. 3.5 logs (99.97%) was achieved at a silver concentration of 0.1 mg/liter, a significant improvement (P < 0.0001) over the ca. 1.8-log (98.42%) inactivation of MS-2 at ca. 40 mJ/cm(2) in the absence of silver. Modified Chick-Watson kinetics were used to model the synergistic effect of silver and UV radiation. For an MS-2 inactivation of 4 logs (99.99%), the coefficient of dilution (n) was determined to be 0.31, which suggests that changes in fluence have a greater influence on inactivation than does a proportionate change in silver concentration.

Coliphages↗
PubMed1990

Disinfection of bacteria in water systems by using electrolytically generated copper:silver and reduced levels of free chlorine.

As an alternative disinfectant to chlorination, electrolytically generated copper:silver (400 and 40 micrograms/L copper and silver, respectively) with and without free chlorine (0.3 mg/L) was evaluated over a period of 4 weeks in indoor and outdoor water systems (100 L tap water with natural body flora and urine). Numbers of total coliform, pseudomonas, and staphylococci were all less than drinking water standards in systems treated with copper:silver and free chlorine and systems treated with free chlorine alone (1.0 mg/L). No significant differences (p less than or equal to 0.05) in bacterial numbers were observed between systems with copper:silver and free chlorine and those with free chlorine alone. Overall, free-chlorine treatments (0.3 or 1.0 mg/L) showed significantly lower heterotrophic plate numbers than those without free chlorine. When challenged with a natural Staphylococcus sp. isolate, water with copper:silver and free chlorine had a 2.4 log10 reduction in bacterial numbers within 2 min, while free chlorine alone or copper:silver alone showed 1.5 and 0.03 log10 reductions, respectively. Addition of copper:silver to water systems may allow the concentration of free chlorine to be reduced while still providing comparable sanitary quality of the water.

Bacteria↗
PubMed2005

Biosynthesis of gold and silver nanoparticles using Emblica Officinalis fruit extract, their phase transfer and transmetallation in an organic solution.

The design, synthesis and characterization of biologically synthesized nanomaterials have become an area of significant interest. In this paper, we report the extracellular synthesis of gold and silver nanoparticles using Emblica Officinalis (amla, Indian Gooseberry) fruit extract as the reducing agent to synthesize Ag and Au nanoparticles, their subsequent phase transfer to an organic solution and the transmetallation reaction of hydrophobized silver nanoparticles with hydrophobized chloroaurate ions. On treating aqueous silver sulfate and chloroauric acid solutions with Emblica Officinalis fruit extract, rapid reduction of the silver and chloroaurate ions is observed leading to the formation of highly stable silver and gold nanoparticles in solution. Transmission Electron Microscopy analysis of the silver and gold nanoparticles indicated that they ranged in size from 10 to 20 nm and 15 to 25 nm respectively. Ag and Au nanoparticles thus synthesized were then phase transferred into an organic solution using a cationic surfactant octadecylamine. Transmetallation reaction between hydrophobized silver nanoparticles and hydrophobized chloroaurate ions in chloroform resulted in the formation of gold nanoparticles.

Colloids↗
PubMed2003

A comparison of the antimicrobial effects of four silver-containing dressings on three organisms.

OBJECTIVE: To compare the antimicrobial activity of four silver-containing dressings: Acticoat (Smith and Nephew), Actisorb Silver 220 (Johnson and Johnson), Avance (SSL International) and Contreet-H (Coloplast). METHOD: The dressings were tested against three micro-organisms: a Gram-positive bacterium, Staphylococcus aureus; a Gram-negative organism, Escherichia coli; and a yeast, Candida albicans, using three different techniques. Each dressing also had its silver content analysed. RESULTS: Acticoat is likely to produce the most rapid antimicrobial effect in vitro because of the rapid release of relatively large concentrations of highly active silver ions. Contreet-H has broadly similar antimicrobial activity to Acticoat, but has a slower onset of action. Actisorb Silver 220 appears to offer less prospect of killing bacteria within the wound itself, but the dressing is capable of removing micro-organisms from wound exudate and sequestering them until they are inactivated by the silver within the charcoal fibres. Little convincing evidence for any antimicrobial activity of Avance was found. CONCLUSION: Although caution must always be exercised when extrapolating the results of laboratory-based studies to the clinical situation, potentially important differences were detected in the antimicrobial activity of the four products examined. It is also possible that the silver ions released by the dressings may have effects on wound healing that are unrelated to their antimicrobial activity. Further work is needed to address this issue.

Bandages↗
PubMed2005

Dual layer and multilayer enhancements from silver film over nanostructured surface-enhanced Raman substrates.

Novel dual layer and multilayer silver film over nanostructure (SFON) substrates have been developed that provide surface-enhanced Raman scattering (SERS) signal enhancements of greater than 1000% compared to conventional single layer SFON substrates. These substrates provide signal enhancement factors of 3.8 x 10(5) and greater for a variety of SERS active analytes. Substrate preparation is accomplished by vapor depositing a thick (approximately 100 nm) layer of silver on top of an underlying layer of alumina nanoparticles, followed by deposition of additional layers of silver with silver oxide layers between them. Unlike previous dual layer silver island based substrates that have been developed, these substrates do not rely on achieving an optimal morphology via deposition of silver. Instead, these substrates rely on the roughness being provided by the original under-layer, providing enhanced substrate homogeneity and more reproducible signals than either silver island substrates or colloidal substrates. In addition, the signal enhancement gives these substrates extended lifetimes compared to conventional single layer SFON substrates. Finally, this study also shows that geometric surface structure and surface roughness factors play little or no role in this enhancement process, allowing for this multilayer fabrication process to be applied to many different types of substrates achieving similar or even greater results.

Benzoic Acid↗
PubMed2000

Silver nitrate is superior to talc slurry in producing pleurodesis in rabbits.

STUDY OBJECTIVE: The ideal agent for producing pleurodesis has not been identified. Although talc is the agent most commonly used at the present time, there are concerns about its safety. Silver nitrate is a possible alternative agent. The purpose of the present study was to compare the effectiveness of intrapleural silver nitrate and talc slurry in producing pleurodesis in rabbits. Additionally, the total amount of pleural collagen and the distribution of thick and thin collagen fibers were studied. DESIGN: Two groups of 10 rabbits received either 0.50% silver nitrate or 400 mg/kg talc in a total volume of 2 mL intrapleurally. The animals were killed 28 days after injection, and the pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of inflammation and fibrosis. Collagen was assessed with the van Gieson's and picrosirius stains. RESULTS: The macroscopic pleurodesis (scale, 0 to 4; mean +/- SEM) resulting from the intrapleural injection of silver nitrate (3.4+/-0.2) was significantly better (p<0.001) than that resulting from talc (1.6+/- 0.1). The mean degree of microscopic pleural fibrosis induced by silver nitrate (3.3+/-0.3) was significantly higher (p = 0.003) than that induced by talc (1.8+/-0.1). The mean amount of microscopic pleural collagen (van Gieson's) was significantly greater (p<0.001) in the rabbits that received silver nitrate (3.0+/-0.2) than in those that received talc (1.6+/-0.2). The distribution of thick and thin collagen fibers did not differ between the groups. CONCLUSIONS: We conclude that, in our rabbit model, intrapleural silver nitrate was more effective than talc in producing a pleurodesis.

Animals↗
PubMed2002

Silver-coated endotracheal tubes associated with reduced bacterial burden in the lungs of mechanically ventilated dogs.

STUDY OBJECTIVES: To evaluate the influence of silver-coated endotracheal tubes on the lung bacterial burden of mechanically ventilated dogs. DESIGN: Randomized, double-blinded, controlled experiment. SETTING: Animal research facility of a regional medical university. PATIENTS OR PARTICIPANTS: Eleven healthy adult dogs. INTERVENTIONS: The dogs were intubated either with cuffed, noncoated endotracheal tubes or with endotracheal tubes having a novel antimicrobial silver hydrogel coating and were challenged with buccal administration of Pseudomonas aeruginosa. MEASUREMENTS AND RESULTS: The silver coating delayed the appearance of bacteria on the inner surface of the endotracheal tubes ([mean +/- SD] duration of mechanical ventilation before appearance of bacteria, 3.2 +/- 0.8 days; mean duration of mechanical ventilation, 1.8 +/- 0.4 days; p = 0.016). The mean total aerobic bacterial burden in the lung parenchyma was statistically lower among the dogs receiving the silver-coated endotracheal tubes compared to those not receiving them (4.8 +/- 0.8 vs 5.4 +/- 9 log cfu/g lung tissue, respectively; p = 0.010). Pronounced differences were seen in the gross and histologic assessments of inflammation in the lung. Using an increasing severity scale of 0 to 12 to assess four components of histology (ie, hyperemia, edema, cellular infiltration, and bacterial presence), dogs receiving noncoated endotracheal tubes had statistically greater histology scores compared to dogs receiving silver-coated endotracheal tubes (7.1 plus minus 1.6 vs 2.8 plus minus 1.2, respectively; p < 0.001). CONCLUSION: These results suggest that the silver coating of endotracheal tubes may delay the onset of and decrease the severity of lung colonization by aerobic bacteria. Based on these results, clinical studies are planned to determine the safety and clinical efficacy of silver-coated endotracheal tubes in patients requiring mechanical ventilation in the ICU setting.

Animals↗
PubMed2005

Intrapleural low-dose silver nitrate elicits more pleural inflammation and less systemic inflammation than low-dose talc.

STUDY OBJECTIVES: Several systemic effects have been described after talc pleurodesis. The aim of this study was to assess the systemic response induced by low, nonpleurodesis-inducing doses of talc and silver nitrate in an experimental model in rabbits. DESIGN: Groups of six rabbits were injected intrapleurally with talc, 100 mg/kg or 400 mg/kg, and silver nitrate, 0.1% or 0.5%. After 6, 24, or 48 h, samples of blood and pleural fluid were collected and assayed for leukocytes, percentage of neutrophils, lactate dehydrogenase, interleukin-8, and vascular endothelial growth factor (VEGF) levels. Preinjection blood samples were used as normal blood controls. MEASUREMENTS AND RESULTS: Silver nitrate 0.1% induced a more intense pleural inflammation than that produced by talc 100 mg/kg. In contrast, talc 100 mg/kg induced a more pronounced acute systemic response with higher values of WBCs and neutrophils, whereas silver nitrate 0.1% produced no significant increases in leukocytes or neutrophils. The serum interleukin-8 and VEGF levels increased in all groups, and decreased with time only in the silver nitrate 0.1% group. The highest serum VEGF levels were observed in the talc 100 mg/kg group. CONCLUSIONS: In conclusion, 0.1% silver nitrate produced an intense pleural inflammatory response with a less evident systemic response in comparison to 0.5% silver nitrate and talc 100 mg/kg or 400 mg/kg.

Animals↗
PubMed1996

Toxicological aspects of topical silver pharmaceuticals.

Silver is generally considered to present a relatively low toxic threat to humans because unintentional exposure to large doses of the noble metal is quite rare. However, as the intentional utilization of silver in pharmaceutical preparations and devices increases, subtle toxic effects of silver may be predictable and expected. The present review examines the scientific literature, primarily covering the past 10 years, dealing with reports describing various types of silver toxicity. These reports consist of both in vitro and in vivo data dealing with immunological, mesenchymal, neural, and parenchymal cell types. Particular emphasis is given to (1) the use of silver in topical antimicrobial preparations as toxicity relates to absorption through dermal wounds into the systemic circulation and possible effects on delayed wound healing, (2) possible local silver toxicity via iontophoretic devices, (3) current theories relating to the toxicological mechanism of action of silver.

Administration, Topical↗
PubMed1985

Some introductory comments on silver staining.

Silver staining has become a versatile method for the visualization of specific cell structures and products. The similarity of the impregnation "nuclei" of reduced silver staining to the silver "specks" or "nuclei" of the latent image in photography is noted. "Physical" development (reduction of ionic silver in solution) in silver staining as compared to "chemical" development (reduction of ionic silver remaining in a silver halide crystal) in photographic procedures is briefly discussed.

Animals↗
PubMed1993

Stimulating effects of mercuric- and silver ions on the superoxide anion production in human polymorphonuclear leukocytes.

In a survey of a number of heavy metal ions for effects on the oxidative metabolism (respiratory burst) of human polymorphonuclear leukocytes (neutrophils) we have found that mercury(II) and silver ions in micromolar concentration significantly increase the production of superoxide anions in cells, initiated by formyl-methionyl-leucylphenylalanine (fMLP). The stimulation of radical formation induced by a certain ion concentration varied considerably in cells isolated from different blood donors, from a moderate increase to a very large (up to 400% of control values). When the soluble stimulator phorbol myristate acetate (PMA) or the particulate stimulator Zymosan were used to initiate the cell respiratory burst, no additional stimulating effects by the metal ions on superoxide anion formation were observed. This fact might indicate that the effect of the metal ions on the fMLP-dependent initiation of cell activity is a mechanism coupled to the interaction between the chemotactic peptide and its corresponding receptor molecules on the cell surface. By increasing the concentration of silver ions during pre-incubation of resting neutrophils, a spontaneous activation of the cells could be recorded at a concentration exceeding 5 microM. However, the silver ion concentration at which such spontaneous initiation of the respiratory burst occurred varied significantly between blood samples from different donors with a concentration range of 5 to 15 microM. This effect could not be shown for mercuric ions due to the toxicity of the metal above 5 microM. Blood samples from some donors contained neutrophils that could be activated by either mercuric- or silver ions at concentration as low at 1 microM. The spontaneous activation of neutrophils with elevated concentrations of silver ions is kinetically similar to the PMA-induced. The onset of superoxide anion formation is preceded by a lag period whose length varies in time with the concentration of agent applied to the cells. It is a known fact that once the neutrophils have been activated with fMLP it is not possible to reactivate the cells by a second supplementation of fMLP. However, after cessation of the fMLP-induced activation, addition of PMA or silver ions gives rise to renewed production of superoxide anions. We propose two different mechanisms of action of silver ions on oxidative metabolism of neutrophils.(ABSTRACT TRUNCATED AT 400 WORDS)

Anions↗
PubMed1975

Interrelationship of dietary silver with copper in the chick.

Adding 900 p.p.m. silver (as silver nitrate) to a practical diet for chicks significantly depressed growth, increased wet and dry heart weight to body weight ratios and markedly increased mortality during a four-week experimental period. Blood packed cell volume was not affected. Supplementing the diet containing silver with 50 p.p.m. copper prevented cardiac enlargement and mortality, but only partially corrected the growth depression. Glycogen content of the heart was not affected, but aortic elastin content was significantly reduced by silver and restored to normal by supplemental copper. Dietary silver significantly reduced the copper content of blood, spleen, brain, liver, but except for the brain, the level of copper in these tissues was restored to normal by dietary copper supplementation. No significant differences in copper content of kidney tissue were observed among the treatment. Copper content of the excreta was not significantly increased by adding dietary silver, but was greatly increased by adding 50 p.p.m copper to the diet containing silver.

Administration, Oral↗
PubMed1994

Pin tract infections: silver vs uncoated pins.

To test the hypothesis that coating external fixation pins with a silver-containing compound (Spi-Argent, Spire Corp, Bedford, Mass) will reduce bacterial colonization and/or pin tract infection, 36 silver-coated and 12 conventional stainless steel pins were placed in the iliac crest of six sheep and inoculated with Staphylococcus aureus. After 2 1/2 weeks the pin sites were examined for motion and inflammation, and the pin tips were quantitatively cultured and examined with scanning electron microscopy (SEM). We found that 84% of the uncoated pins were infected, while 62% of the silver-coated pins were infected. Silver-coated pins were less frequently infected than uncoated pins (confidence interval [CI] > 85%). Also, silver-coated pins were loose less frequently than uncoated pins. Pin motion was closely correlated with infection: 28 of 32 infected pins (88%) had motion, while only 9 of 16 uninfected pins (56%) had motion (CI > 80%). SEM study of the pin tips showed a decreased level of glycocalyx-protected colonization on the surface of the silver-coated pins. Clinically, these results suggest that silver-coated pins will result in less infection and motion at the pin site, the most significant problems in external fixation.

Animals↗
PubMed1989

Absence of toxic effects in silver reclamation workers.

Recent reports have alleged that silver presents a toxic hazard to exposed workers. To define the potential risks of long-term exposure to silver better, a cross-sectional investigation was conducted of 27 Caucasian males occupationally exposed to primarily insoluble silver compounds and 27 matched referents. Physical examination and electron microscopy of skin biopsies revealed no cases of generalized argyria. Measurements of facial discoloration, judged from color photographs by panels of laymen and physicians, showed no significant difference between the two groups. Although 29% of the silver workers and none of the referents exhibited ocular silver deposition, optometric and contrast sensitivity test results revealed no significant deficits in visual performance. The kidney and respiratory findings were essentially normal in both populations. Despite the increased presence of silver in the blood, feces, and hair of the recovery workers versus the referents, there was no evidence that chronic silver exposure adversely affected the health of these employees.

Air Pollutants, Occupational↗
PubMed2002

Physiological responses to acute silver exposure in the freshwater crayfish (Cambarus diogenes diogenes)--a model invertebrate?

Adult crayfish (Cambarus diogenes diogenes) exposed to 8.41 +/- 0.17 microg silver/L (19.4% as Ag+) in moderately hard freshwater under flow-through conditions for 96 h exhibited ionoregulatory disturbance, elevated metabolic ammonia (T(amm)) production and substantial silver accumulation in the gills, hemolymph, and hepatopancreas. The ionoregulatory disturbance included both a generally reduced unidirectional Na+ influx and an increased unidirectional Na+ efflux, leading to a substantial net loss of Na+ from the silver-exposed crayfish. The Na+ uptake in silver-exposed crayfish differed overall from controls, while the increased Na+ efflux recovered to control values 48 h into the 96 h of exposure. The general inhibition of Na+ uptake could be explained by a reduced sodium/potassium-adenosine triphosphatase (Na/K-ATPase) activity in terminally obtained gill samples from the silver-exposed crayfish. The silver-induced effect on Na+ uptake and loss translated to reduced hemolymph Na+ concentrations but not significantly reduced hemolymph Cl- concentrations. Hemolymph T(anim) and T(amm) efflux both increased in silver-exposed crayfish, indicating an increased metabolic T(amm) production. The present study demonstrates that the toxic mechanism of waterborne silver exposure in freshwater crayfish resembles that of freshwater teleost fish. The crayfish might therefore be a useful model system for extending current environmental regulatory strategies, currently based on teleost fish, to invertebrates.

Ammonia↗
PubMedDate not supplied

Preconcentration of trace silver with yeast for river water analysis.

A new preconcentration method with yeast is presented. The method was evaluated for the determination of trace silver in river waters by graphite furnace atomic absorption spectrometry (GFAAS). A suitable cultivation bed for preconcentration of silver was 1.75 mg ml-1 2-ammonium hydrogen phosphate. The optimal cultivation time and temperature were 2 h and 25 degrees C. Under optimal conditions, silver in aqueous sample was concentrated to 6.9-fold by yeast. The detection limit was 4.6 pg ml-1 (3S/N) for silver in river water. The yeast preconcentration method was applied to the determination of silver in river waters. The recovery of spiked silver was in the range of 89 to 110%. By the preconcentration, it was found that ultra trace silver in river waters could be determined without interferences of matrix elements, after only the cultivation and with no chemical treatment.

Fresh Water↗