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PubMed1989

[Serum and tissue silver levels after burns treated with silver compounds].

This study was performed in order to investigate serum and tissue silver levels in burns which were used 10 percent silver nitrate as a topical agent. We formed four groups of animals and pulverized 10 percent silver nitrate solution to the first group (GI) that included ten rabbits of which backs were burned by boiling water and silver sulphadiazine cream to second group (GII) with nine rabbits. We carried out 10 percent silver nitrate solution to the first control group (GIII) and silver sulphadiazine cream to the second control group (GIV) each of which had seven animals with unburned skin. We obtained blood samples from every animal before and after application of topical agent on the 1st, 3rd, 7th, 15th, 21st and 28th. We determined serum and tissue silver levels by atomic absorption spectrophotometer in kidney and liver of the animals which were sacrificed on the 28th day. In first and second groups we found that serum silver values reached on 3rd day to the maximum level and then the values decreased gradually. We also determined that diminution of the serum silver levels were prominent following on 15th day. It was shown that there was no silver in the serum on 28th day except four animals. The silver deposition in the liver was much more than in the kidney. Between these two groups there was significant difference neither in the serum on the same days nor the tissue silver levels. According to these data it was concluded that serum and tissue silver levels with 10 percent silver nitrate used in burns produced no difference from that of 1 percent silver sulphadiazine cream.

Administration, Topical↗
PubMed2002

[Increased serum and urinary levels of silver during treatment with topical silver sulfadiazine].

BACKGROUND: Argyria, induced by prolonged absorption, is often of professional or medical origin. We report two cases of per cutaneous intoxication with topical silver sulfadiazine. CASE REPORTS: A 64 year-old hypertensive, diabetic woman presented bilateral venous ulcers on the legs. She had applied 100 g of silver sulfadiazine 1 p. 100 cream per week for the past 18 months. Silver concentration in blood high: 38 microgram/l (N<0.5) and led to renal dysfunction, without ocular or hepatic abnormality. A 19 year-old woman was treated with topical silver sulfadiazine for thermic cutaneous burns on legs. Renal and hepatic function was normal but silver concentration in blood was high at 440 microgram/l (N<0) with urinary excretion of silver at 12 microgram/l (N=0). DISCUSSION: Silver, from prolonged and excessive use of topical silver sulfadiazine, deposits in large amounts throughout the body: skin, labial mucosa, gingiva, kidney, liver and cornea. Monitoring concentration of silver in blood and/or urine is necessary, especially in patients treated with silver sulfadiazine cream for cutaneous burns. Indeed, silver is rapidly absorbed through the burn wound. It provokes hepatic, renal and neurologic tissue toxicity. Renal and hepatic function tests are not correlated with serum silver levels. CONCLUSION: The potential for silver toxicity is a direct consequence of applying silver sulfadiazine to extensive burn wounds. Hence monitoring concentrations of silver in blood and/or urine of patients receiving this treatment is recommended.

Adult↗
PubMed2000

Adduct formation or metathesis reactions of silver complexes containing the fluorinated ligands [HB(3,5-(CF3)2Pz)3]- and [CF3SO3]-: formation of silver adducts containing unsupported silver-germanium bonds.

A mixture of [HB(3,5-(CF3)2Pz)3]Ag(eta 2-toluene) and [(Me)2ATI]GeCl in CH2Cl2, rather than undergoing metathesis, formed a 1:1 adduct [HB(3,5-(CF3)2Pz)3]Ag<--GeCl[(Me)2ATI] (1, where [HB(3,5-(CF3)2Pz)3] = hydrotris(3,5-bis(trifluoromethyl)pyrazolyl)borate and [(Me)2ATI] = N-methyl-2-(methylamino)troponiminate) featuring a silver-germanium bond. Solutions of 1 (in CH2Cl2 or toluene) did not precipitate AgCl even after several days. However, it easily underwent metathesis with CF3SO3Ag, leading to the chloride-free product [HB(3,5-(CF3)2Pz)3]Ag<--Ge(OSO2CF3)[(Me)2ATI] (2). Compounds 1 and 2 were characterized by X-ray crystallography. The Ag-Ge bond distances of 1 and 2 are 2.4215(9) and 2.4116(10) A, respectively.

Journal Article↗
PubMed2000

Effects of an acute silver challenge on survival, silver distribution and ionoregulation within developing rainbow trout eggs (Oncorhynchus mykiss).

Rainbow trout eggs were acutely challenged with silver (as AgNO(3)) at different stages of development from fertilization through to hatch in moderately hard water (120 mg CaCO(3) l(-1), 0.70 mM (25 mg l(-1)) Cl(-), 1.3 mg l(-1) DOC, 12.3+/-0.1 degrees C) at measured total silver concentrations of 0.11+/-0.004, 1.55+/-0.15, and 14.15+/-1.52 microg l(-1). Four separate acute challenges were conducted, each consisting of 5 days exposure to the respective silver concentration, followed by 4 days recovery after transfer to silver-free water (series 1, 1-10 days post-fertilization; series 2, 8-17 days post-fertilization; series 3, 16-25 days post-fertilization; series 4, 23-32 days post-fertilization). Mortality was not significantly different from control during exposure to 0.11, 1.55, and 14.15 microg l(-1) total silver in series 2, 3 and 4 (mortality for series 1 data could not be calculated for technical reasons). In the four days of recovery following silver exposure, however, there was significant mortality at 14.15 microg l(-1) total silver reaching 100, 31 and 72% in series 2, 3 and 4, respectively, indicating eggs are more sensitive in the period of 8-17 and 23-32 days post-fertilization at this temperature. Mortality following silver exposure was associated with ionoregulatory impairment in series 3 and 4, where up to 60% of whole egg [Na(+)] and [Cl(-)] was lost relative to controls at 14.15 microg l(-1) total silver. Significant but smaller reductions in egg [Na(+)] and/or [Cl(-)] were also observed at 0.11 and 1.55 microg l(-1) total silver. The greatest accumulation of silver in whole eggs and chorions occurred in series 4, reaching concentrations of 0.53 microg g(-1) (eggs) and 15.5 microg g(-1) (chorions) in the 14.15 microg l(-1) treatment. The accumulation of silver in the whole eggs and chorions of the 0.11 microg l(-1) treatment was not different from controls throughout embryonic development. Of the total silver content, only a small proportion of silver was found in the embryos (1-17%), indicating that the chorion is a protective barrier during acute silver exposure.

Animals↗
PubMed2000

A nose-to-nose comparison of the physiological effects of exposure to ionic silver versus silver chloride in the European eel (Anguilla anguilla) and the rainbow trout (Oncorhynchus mykiss).

Physiological mechanisms of silver toxicity (as silver nitrate) to the sensitive rainbow trout (Oncorhynchus mykiss) (96 h LC50: 10.2 µg silver l(-1), in soft, low chloride water) and the more tolerant European eel (Anguilla anguilla)(96 h LC50: 34.4 µg silver l(-1), in the same water) were investigated during acute exposure to silver, using concentrations varying from 3 to 22 µg silver l(-1). Silver was present either predominantly in the form of ionic silver, or in the form of silver chloride complexes (AgCl(aq)). Inhibition of the branchial Na(+),K(+)-ATPase enzyme activity and the active influx of Na(+) leading to net Na(+) loss were the key toxic effect in both species. In the rainbow trout, but not in the European eel, Cl(-) influx was also impaired during silver exposure. However, even under control conditions, Cl(-) influx was negligible in the eel. Water Cl(-) clearly protected against the silver-induced physiological disturbance in rainbow trout, presumably by changing the speciation of silver from ionic silver to AgCl complexes. However, such a protective effect was not observed in the European eel. Differences in whole body Na(+) turnover rates between the two species (1.1% per day in the European eel versus 19% per day in the rainbow trout) together with the lack of effect of silver exposure on Cl(-) homeostasis in the European eel are hypothesized to be the main reasons for the different silver tolerance observed in the two species.

Journal Article↗
PubMed1983

Localization of exogenous silver in brain and spinal cord of silver exposed rats.

Exogenous silver in brain and spinal cord sections from rats treated with Protargol, silver lactate or silver nitrate was visualized by physical development. The silver penetrated the blood-brain barrier and accumulated in neurones and glia. The distribution of silver in the CNS was heterogeneous. Even with low doses and short survival periods, silver was found to accumulate in large motoneurones in the brain stem and spinal cord and neurones in the cerebellar nuclei. Silver was only found in di- and telencephalic structures after extensive exposure. Silver distribution following oral silver lactate and silver nitrate treatment differed in that silver nitrate resulted in a relatively high content of silver in glia whereas deposition occurred preferentially in neurones following silver lactate treatment. Electron-microscopical studies showed that silver was located intracellularly in the lysosomes and extracellularly in basement membranes and elastic fibres of the vessels.

Animals↗
PubMed2006

An investigation of the surface enhanced Raman scattering (SERS) from a new substrate of silver-modified silver electrode by magnetron sputtering.

'Pure' silver nanoparticles on silver electrode were prepared by magnetron sputtering. The silver-modified silver electrode has good stability and the silver nanoparticles on silver electrode have homogeneous size distribution. Compared with the silver colloid modified silver electrode, there were no any extraneous component ions on the electrode, for the modified silver nanoparticles are prepared by magnetron sputtering. Synchronously, we obtained much higher quality SERS spectra of adenine molecules on the silver electrode modified by magnetron sputtering (SEMMS), and the study of the adsorption behavior of adenine on the silver-modified silver electrode by surface enhanced Raman scattering (SERS) indicated that the silver-modified silver electrode was highly efficient substrates for SERS investigation. From the rich information on the SEMMS obtained from high-quality potential-dependent SERS, we may deduce the adsorption behavior of adenine and the probable SERS mechanism in the process. The probable reasons are given.

Adenine↗
PubMed2005

Silver absorption and antibacterial efficacy of silver dressings.

OBJECTIVE: To evaluate the patterns of silver release from selected sustained silver-release dressings and the protective role of proteins in wound exudate and wound scale. The bactericidal action of silver in chronic wound therapy is also examined. METHOD: Sequential microbiological examination of wound swabs from seven patients with chronic wounds and sampling of wound exudate and wound scale. Silver content was measured using atomic absorption spectrometry. The ability of Contreet Foam to absorb exudate and release silver was studied in punch biopsy wounds in a rodent model. RESULTS: Silver accumulation in wound exudate correlated well with its viscosity and protein content. Silver bound to wound scale and debris was approximately proportional to the silver ion release from dressings. Bacterial burden was controlled, but not eliminated, following chronic silver therapy. CONCLUSION: Silver dressings (Acticoat-7, Actisorb Silver, Contreet Foam, Aquacel Ag and Flamazine) were found to be safe for use in chronic wound therapy. Excess silver ion is bound by wound exudate and wound scale as a protective mechanism. Silver-release dressings are not likely to result in germ-free wounds. Further studies are needed to examine potential silver resistance.

Aged↗
PubMed2002

Electronic properties of the silver-silver chloride cluster interface.

The objective of this study was to gain insight into the electronic structure of silver-silver chloride cluster composites and especially into the metal-semiconductor interface. For this purpose a theoretical study of (AgCl)(n) (n=4, 32, 108, 192, and 256), of Ag(m) (m=1-9, 30, 115, 276, and 409), and of the cluster composites Ag(115)-(AgCl)(192) and Ag(409)-(AgCl)(192) has been carried out. Density of levels (DOL), local density of levels (l-DOL), and projection of surface states, as well as projection of properties of individual atoms or groups of atoms obtained in molecular orbital calculations, are shown to be powerful tools for gaining deep insight into the properties of these large systems. The Ag(115)-(AgCl)(192) aggregate, consisting of a cubic Ag(115) cluster without corner atoms on top of a cubic (AgCl)(192) cluster, was found to be remarkably stable with a cluster-to-cluster distance of about 280 pm, and a geometry in which the number of bonding interactions between the silver atoms of Ag(115) and the chloride ions of (AgCl)(192) is at its maximum. A sharp jump in charge distribution occurs at the Ag(115)-(AgCl)(192) composite interface. The first AgCl slab picks up negative charge from the two adjacent silver slabs, so that in total the silver cluster is positively charged. In addition, the core of the silver cluster is positively charged with respect to its outermost layer. The main reason for the charge transfer from the silver cluster to the silver chloride is the newly formed MIGS (metal induced gap states) in the energy-gap range of the silver chloride and the MIdS (metal induced d states) in the d-orbital region. Their wave functions mix with orbitals of the silver cluster and with both the orbitals of the silver and the chloride ions of the silver chloride. The MIGS and the MIdS are of a quite localized nature. In them, nearest neighbor interactions dominate, with the exception of close-lying silver chloride surface states-which mix in to a large extent. We conclude that especially the MIGS not only influence the photochemical properties of silver chloride, but that their existence might be probed by appropriate spectroscopic measurements.

Journal Article↗
PubMed2004

Sensitive silver staining of protein in sodium dodecyl sulfate-polyacrylamide gels using an azo dye, calconcarboxylic acid, as a silver-ion sensitizer.

A highly sensitive silver staining method for detecting proteins in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was developed. It is based on the silver nitrate staining method but also employs an azo dye, calconcarboxylic acid (NN), as a silver-ion sensitizer. It increases silver binding on protein bands or spots by the formation of a silver-dye complex and also increases the reducing power of silver ions to metallic silver by NN itself with formaldehyde. After a 2 h gel fixing step, the protocol including sensitization, silver-ion impregnation, and reduction steps can be completed in 1 h. The sensitivity is superior to that of silver stain with glutardialdehyde as a silver-ion sensitizer. The detection limit of NN-silver stain is 0.05-0.2 ng protein. Considering the high sensitivity without using glutardialdehyde, the NN-silver stain would be useful for routine silver staining of proteins.

Azo Compounds↗
PubMed1996

The mechanism of Bodian's silver staining: effect of copper ion on silver impregnation.

We studied the effect of the duration (0.5-48 h) of silver impregnation on the intensity of Bodian's silver staining using formalin-fixed, paraffin-embedded sections of a human brain. The silver ion (Ag+) and copper ion (Cu2+) in the silver protein solution were quantified simultaneously for treatments of various durations. Both the intensity of staining and the quantities of Ag+ and Cu2+ were greatly affected by the duration of silver impregnation. While the quantity of Ag+ considerably decreased during the first 4 h of impregnation, that of Cu2+ greatly increased. Only small changes were observed in both ions after 12 h. Neurofibrils or axons, and neurofibrillary tangles (NFTs) were clearly stained after 12-24 and 16-48 h of impregnation, respectively. Strong staining of these components was not observed for other durations of treatment. The amount of metallic copper in silver impregnation also affected both the intensity of staining and the quantities of Ag+ and Cu2+ in the silver protein solution. Ag+ and Cu2+ were also present in the gold trichloride acid solution in which the section was toned. These findings suggest that both Cu2+ derived from metallic copper and silver protein are deposited on sections during silver impregnation, that the amount of Cu2+ may determine the amount of silver protein deposited on the section, and that the reduced (metallic) form of silver and copper on the section may participate in gold toning. Thus, to achieve strong staining of a desired component, it is important to examine the conditions of silver impregnation (i.e. duration and amount of metallic copper). For strong staining of neurofibrils, axons and NFTs, optimal results are obtained by the addition of 5 g of metallic copper foil to 100 ml of 1% silver protein solution, and by 16-24 h of impregnation.

Aged↗
PubMed2003

Comparison of discharge silver concentrations from electrolytic plating and metallic replacement silver recovery units.

Silver-based photographic X-ray film is made of solid crystals of silver chloride or silver bromide suspended in a gelatin and then coated on a film. During the X-ray developing process, the image is processed and the nonimage areas containing solid silver chloride or silver bromide crystals are removed in a solution called the fixer. There may be local environmental regulations that regulate the amount of silver discharged from a facility. To meet these regulations, many facilities have added silver recovery units to their processes. Two different types of recovery processes are in use in a large hospital and three clinics under study. All of the units were claimed by their respective manufacturers to be able to recover silver down to concentrations of 5 mg/L. This concentration would ensure that the building that houses each unit would meet the local county limit of 0.5 mg/L silver for total building silver discharge. The hypothesis for this research is that one system, newer and more expensive, consisting of so-called electrolytic plating units (EPUs) (which are followed by so-called metallic replacement units [MRUs] as a backup), will have better silver recovery than MRUs alone. A total of six units were sampled, three EPUs (in combination with MRUs) and three MRUs. The units were sampled once or twice a day for 10 days for a total of 17 samples from each. The samples then were analyzed by inductively coupled plasma spectroscopy, and an analysis of variance was performed on the results. The range for the electrolytic plating unit/metallic replacement unit combinations was 0.20-99.9 mg/L (mean of 35.15 mg/L; median of 33.8 mg/L). The range for the MRUs alone was 7.2-1112 mg/L (mean of 565.5 mg/L; median of 720 mg/L). Many individual results exceeded 5 mg/L, such that extensive dilution would be required to ensure the building effluent did not exceed 0.5 mg/L. It is suggested that the metallic replacement units be changed to EPUs (with metallic replacement backup units) because they had better silver recovery. Also, the EPU combinations need to be sampled regularly to ensure that their silver concentrations are at acceptable levels.

Conservation of Natural Resources↗
PubMed2006

Silver deposition and tissue staining associated with wound dressings containing silver.

Argyria is the general term used to denote a clinical condition in which excessive administration and deposition of silver causes a permanent irreversible gray-blue discoloration of the skin or mucous membranes. The amount of discoloration usually depends on the route of silver delivery (ie, oral or topical administration) along with the body's ability to absorb and excrete the administered silver compound. Argyria is accepted as a rare dermatosis but once silver particles are deposited, they remain immobile and may accumulate during the aging process. Topical application of silver salts (eg, silver nitrate solution) may lead to transient skin staining. To investigate their potential to cause skin staining, two silver-containing dressings (Hydrofiber and nanocrystalline) were applied to human skin samples taken from electively amputated lower limbs. The potential for skin discoloration was assayed using atomic absorption spectroscopy. When the dressings were hydrated with water, a significantly higher amount of silver was released from the nanocrystalline dressing compared to the Hydrofiber dressing (P <0.005), which resulted in approximately 30 times more silver deposition. In contrast, when saline was used as the hydration medium, the release rates were low for both dressings and not significantly different (silver deposition was minimal). Controlling the amount of silver released from silver-containing dressings should help reduce excessive deposition of silver into wound tissue and minimize skin staining.

Administration, Cutaneous↗
PubMed2006

Size-controlled synthesis of monodispersed silver nanoparticles capped by long-chain alkyl carboxylates from silver carboxylate and tertiary amine.

Monodispersed silver nanoparticles capped by long-chain alkyl carboxylates were prepared by the reaction of silver carboxylate with tertiary amine at 80 degrees C for 2 h. This approach is a unique, size-controlled synthetic method for the large-scale preparation of silver nanoparticles. Long-chain alkyl carboxylate derived from a precursor acts as a stabilizer to avoid the aggregation of silver nanoparticles and to control particle size. In addition, amine plays an important role both as a reagent to form a thermally unstable, amine-coordinated intermediate, bis(amine)silver(I) carboxylate, and as a mild reducing agent for the intermediate to produce nanoparticles at a low temperature. The silver core and carboxylate-capping ligand of silver nanoparticles were characterized by various techniques such as transmission electron microscopy, optical absorption spectroscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, gas chromatograph mass spectroscopy, and thermogravimetric and differential thermal analysis. The diameter of the nanoparticles can be strongly influenced by the alkyl chain length and the structure of the carboxylate. The average diameters of the silver nanoparticles were controlled to less than 5 nm in the case of silver carboxylate with a single alkyl chain length of 13 or 17 carbon atoms. On the contrary, the average diameters of silver nanoparticles became large and polydisperse in the case of silver carboxylate with a chain length of 7 carbon atoms or a branched chain. In comparing triethylamine with trioctylamine, there was no obvious effect to regulate the size distribution of the nanoparticles because they could not function as a capping ligand of the nanoparticles due to their weak coordination to silver. In addition, the heat treatment of silver nanoparticles in solution rather than in the solid state was effective for the growth of particles while maintaining narrow size distributions.

Journal Article↗
PubMed2005

Exposure-related health effects of silver and silver compounds: a review.

A critical review of studies examining exposures to the various forms of silver was conducted to determine if some silver species are more toxic than others. The impetus behind conducting this review is that several occupational exposure limits and guidelines exist for silver, but the values for each depend on the form of silver as well as the individual agency making the recommendations. For instance, the American Conference of Governmental Industrial Hygienists has established separate threshold limit values for metallic silver (0.1 mg/m3) and soluble compounds of silver (0.01 mg/m3). On the other hand, the permissible exposure limit (PEL) recommended by the Occupational Safety and Health Administration and the Mine Safety and Health Administration and the recommended exposure limit set by the National Institute for Occupational Safety and Health is 0.01 mg/m3 for all forms of silver. The adverse effects of chronic exposure to silver are a permanent bluish-gray discoloration of the skin (argyria) or eyes (argyrosis). Most studies discuss cases of argyria and argyrosis that have resulted primarily from exposure to the soluble forms of silver. Besides argyria and argyrosis, exposure to soluble silver compounds may produce other toxic effects, including liver and kidney damage, irritation of the eyes, skin, respiratory, and intestinal tract, and changes in blood cells. Metallic silver appears to pose minimal risk to health. The current occupational exposure limits do not reflect the apparent difference in toxicities between soluble and metallic silver; thus, many researchers have recommended that separate PELs be established.

Argyria↗
PubMed1995

Solubility of silver sulfadiazine in physiological media and relevance to treatment of thermal burns with silver sulfadiazine cream.

Silver sulfadiazine cream has been a standard treatment for burns over the past two decades. Although many studies have described the phenomenon of silver absorption from burn wounds treated with silver sulfadiazine, they failed to examine the chemistry underlying the absorption process: Silver chloride was assumed to form at the burn wound and absorption of silver was believed to be negligible. Here we have developed chemical model systems to investigate the interactions of silver sulfadiazine and silver chloride in direct contact with synthetic serum electrolyte solution (SSES), with SSES plus endogenous ligands or beef blood plasma, and with human serum. The results indicate that silver absorption from an acute burn site can be significant, because human serum is capable of solubilizing silver. This finding is of concern, given the potential for silver toxicity as a direct consequence of applying silver sulfadiazine to extensive burn wounds.

Absorption↗
PubMed1997

Passage of silver ions through membrane-mimetic materials, and its relevance to treatment of burn wounds with silver sulfadiazine cream.

Treatment of acute burn wounds with silver sulfadiazine has raised concern of potential silver toxicity. As the wound heals, a barrier forms between the silver sulfadiazine and the blood, but this membrane is not impenetrable, and so silver absorption is still possible. In this work, we have modeled chemical systems to investigate the transport of silver sulfadiazine and silver chloride through cellulose, chitosan, collagen, and polyethylene membranes into the following media: synthetic serum electrolyte solution (SSES), SSES plus glutathione, and human serum, to simulate some of the chemical processes occurring at a burn wound during healing. Our results clearly indicate that membranes can retard the movement of silver ions, especially those that have silver-binding properties. This suggests that silver absorption at a healing wound will be minimized by entrapment of silver in the growing membrane network, and thus the likelihood of silver toxicity will be reduced.

Absorption↗