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PubMed1994

Recovery of silver from radiographic fixer.

This study examined the silver content of 10 brands of dental x-ray film that are commercially available in Japan. Kodak Ektaspeed EP-22 (Eastman Kodak Co., Rochester, N.Y.) was found to have the highest silver content, and SD 100 Gold X-ray Film (San Dental Co., Ltd., Tokyo, Japan) had the lowest content of silver. Electrolysis and ion exchange were used as the methods of silver recovery from films in the general dental office. Ion exchange was more than 99% efficient in silver recovery from the radiographic fixer and resulted in an 80% reduction in biochemical oxygen demand and a 95% reduction in chemical oxygen demand. However, these levels and other environmental pollutants were still above the limits set by the Japanese Pollutant Control law.

Dental Waste↗
PubMed1988

Mercury localization in mouse kidney over time: autoradiography versus silver staining.

Several methods of silver staining have been employed to localize mercury in tissue, under the assumption that the techniques represent total Hg, but recent reports have suggested that these stains are specific for a limited fraction of the Hg present in some samples. Magos et al. (1985, Arch. Toxicol. 57, 260-267) hypothesized that the stains actually vary with inorganic mercury content. The purpose of the present study was to compare localization by radiolabeling to localization by one silver stain, the photoemulsion histochemical technique, in tissues prepared to contain a range of levels of total Hg and a range of levels of inorganic Hg. Mice dosed with 8 mg Hg/kg as MeHg were killed 24 hr, 1 week, or 2 weeks after exposure, to allow a decrease in total Hg and an increase in the proportion of demethylated Hg over time. Mice dosed with 4 mg Hg/kg as HgCl2 provided samples in which all the Hg present was in the inorganic form. Atomic absorption of kidneys of mice dosed with MeHg showed that total Hg fell from 55 micrograms/g to 39 to 25 over 2 weeks, while the inorganic fraction climbed from about 2 to 27 to 35%. Grain counts from autoradiographs of 203Hg-labeled sections correlated with total Hg content at +0.88, but silver staining was correlated with inorganic Hg content, appearing only at late termination times in MeHg-exposed animals, but soon after dosing in mice exposed to inorganic Hg. The photoemulsion histochemical technique revealed a substance strictly localized in the proximal tubules, while autoradiographs and grain counts showed total Hg to be present throughout the kidney tissue. These results support the contention that silver stains are selective for inorganic Hg and suggest that the distribution of inorganic Hg, whether introduced experimentally or by gradual demethylation, is different from the distribution of MeHg. If subsequent studies support the association of silver stains with inorganic Hg, it should be possible to localize Hg in histologic sections, distinguishing between organic and inorganic forms, which differ in toxicity.

Animals↗
PubMed1989

An investigation into the permeability of composite materials using silver nitrate.

A new effect of silver-nitrate staining on dental composites and unfilled polymers has been observed which may be useful in the study of polymer permeability. After extended storage in silver nitrate, the materials developed a layer of brown stain in the subsurface. The color was thought to be caused by the presence of finely divided silver precipitated in microcavities within the composite. Energy Dispersive Analysis by x-ray confirmed the presence of silver in the stained zone. The width and shade of staining varied in different materials. After 90 days, layers of different shades could be seen within the stained zone. The exact shade of the stain is thought to depend upon the size of the precipitated silver particles, which is directly related to the sizes of the microcavities.

Absorption↗
PubMed1984

Silver bands in chronic granulocytic leukemia: I. Increased banding associated with blastic transformation.

We have tested the proposal that the level of silver banding in leukemic cells of Ph1 + chronic granulocytic leukemia (CGL) patients increases as the disease progresses. Blood and/or bone marrow cells from 14 patients were cultured for 24 hr before banding. In all but one case, there were two populations of mitoses, those with silver bands on their nucleolar organizing regions (NORs) and those without. The percentage of cells that banded was higher, on average, in cultures from 7 patients in blastic transformation (80%) than in 8 chronic cases (36%) or in one accelerated phase (49%). Also, the mean number of NORs stained in banded cells was higher in blastic phase (6.9) compared with chronic phase cells (4.4). Hyperdiploid cell lines were present in four cases of myeloblastic transformation. All such cells were silver banded, and the mean fraction of NORs banded in them was relatively high. An increase in silver banding with time was shown in two of the patients. It seems that silver banding does increase in CGL cells as the disease progresses. This may arise either through an increase in the rate of ribosomal RNA synthesis in leukemic cells present in the blastic phase or possibly by a decrease in the rate of degradation (or processing) of newly synthesized rRNA.

Adult↗
PubMed1994

Antibacterial activity of Actisorb Plus, Actisorb and silver nitrate.

Activated Charcoal Cloth with silver (Actisorb Plus) and solutions of silver nitrate, but not Actisorb (Activated Charcoal Cloth without silver), demonstrated antibacterial activity against Gram-negative and Gram-positive bacteria. This activity was unimpaired in the presence of plasma. Sodium thioglycollate was an effective neutralizer of Actisorb Plus and of silver nitrate, indicating that the release of silver from Actisorb Plus contributed to the antibacterial activity of the dressing.

Charcoal↗
PubMed1993

N-ethylmaleimide inhibition of silver-enhanced sodium transport across toad (Bufo macinus) skin.

1. Silver stimulated short-circuit current and transepithelial potential difference. 2. N-Ethylmaleimide inhibited the silver-induced short-circuit current. 3. There was a biphasic inhibition of silver-induced short-circuit current by N-ethylmaleimide. 4. There is a specific, maximal number of sulfhydryl groups associated with active sodium absorption. 5. Stimulation of active sodium transport by antidiuretic hormone was blunted by the presence of silver. 6. The silver-induced short-circuit current is carried by a net active sodium transfer from the outside to the inside bathing solution.

Animals↗
PubMedDate not supplied

Use of an amino-cupric-silver technique for the detection of early and semiacute neuronal degeneration caused by neurotoxicants, hypoxia, and physical trauma.

A new amino-cupric silver protocol is described for detection of neuronal degeneration. We describe its selectivity in visualizing both early and semiacute degeneration after intracerebral or systemic administration of a variety of neurotoxicants in rats, and after transient ischemic episodes in gerbils. As early as 5 min after physical trauma, or 15 min following either intrastriatal injections of glutamate analogs or exposure to ischemic episodes, neuronal silver staining was evident at primary sites of trauma (i.g. injection sites) and at hodologically related secondary sites. With intoxication by peripheral injections of trimethyltin (IP) or intracerebral injections of Doxorubicin, reproducible patterns of degeneration are demonstrable after 24 h or after 9-13 days, respectively. The amino-cupric silver method permits simultaneous detection of all neuronal compartments against a clear background. Degeneration in the neuronal cell bodies, dendrites, axons and terminals, as well as the recruitment of new structures in a progressive pathologic process, could be accurately followed. The inclusion of new reagents increased the sensitivity vis-à-vis previous versions of the cupric-silver method. The advantages and disadvantages of the current method in comparison with other means of neurotoxic assessment are discussed in detail, with special emphasis on its unique ability to discriminate irreversible degenerative phenomena and degeneration of axonal components in cases where the cell body remains apparently intact. The amino-cupric silver method is an especially useful tool for surveying neuronal damage in basic neuroscience investigations and in neuropathologic and neurotoxic assessment.

Animals↗
PubMed2006

Short-term exposure to waterborne free silver has acute effects on membrane current of Xenopus oocytes.

Waterborne free silver can cause osmo- and ionoregulatory disturbances in freshwater organisms. The effects of a short-term exposure to extracellular Ag+ ions on membrane currents were investigated in voltage-clamped defolliculated Xenopus oocytes. At a holding potential of -60 mV, ionic silver (1 microM Ag+) increased inward currents (=I(Ag)) from -8+/-2 nA to -665+/-41 nA (n=74; N=27). I(Ag) activated within 2 min of silver exposure and then rose impetuously. This current was largely reversible by washout and repeatable. I(Ag) reversed around -30 mV and rectified slightly at more positive potentials. Na+-free bath conditions reduced the silver-induced current to a smaller but sustained current. The response to silver was abolished by the Cl- channel blockers DIDS and SITS, whereas niflumic acid strongly potentiated I(Ag). Intraoocyte injection of AgNO3 to about 1 mM [Ag]i strongly potentiated I(Ag). Extracellular application of either dithiothreitol (DTT), a compound known to reduce disulfide bridges, or L-cysteine abolished Ag+-activated increase of membrane current. In contrast, n-ethylmaleimide (NEM) which oxidizes SH-groups potentiated I(Ag). Hypoosmotic bath solution significantly increased I(Ag) whereas hyperosmolar conditions attenuated I(Ag). The activation of I(Ag) was largely preserved after chelation of cytosolic Ca2+ ions with BAPTA/AM. Taken together, these data suggest that Xenopus oocytes are sensitive to short-term exposure to waterborne Ag+ ions and that the elicited membrane currents result from extra- and intracellular action of Ag+ ions on peptide moieties at the oocyte membrane but may also affect conductances after internalization.

Animals↗
PubMed2005

Surface characterization of silver-doped bioactive glass.

A bioactive glass belonging to the system SiO(2)-CaO-Na(2)O was doped with silver ions by ion exchange in molten salts as well as in aqueous solution. The ion exchange in the solution was done to check if it is possible to prepare an antimicrobial material using a low silver content. The doped glass was characterized by means of X-ray diffraction, SEM observation, EDS analysis, bioactivity test (soaking in a simulated body fluid), leaching test (GFAAS analyses) and cytotoxicity test. It is demonstrated that these surface silver-doped glasses maintain, or even improve, the bioactivity of the starting glass. The measured quantity of released silver into simulated body fluid compares those reported in literature for the antibacterial activity and the non-cytotoxic effect of silver. Cytotoxicity tests were carried out to understand the effect of the doped surfaces on osteogenic cell adhesion and proliferation.

Anti-Bacterial Agents↗
PubMed2005

Impact of heat on nanocrystalline silver dressings. Part I: Chemical and biological properties.

Thermal stability of heat-treated nanocrystalline silver dressings was investigated using chemical techniques and biological assays. Dressings were heat-treated for 24h at temperatures from 23 to 110 degrees C. Bactericidal efficacy of heat-treated dressings was measured using a log reduction assay, while antibacterial longevity was determined via plate-to-plate transfer corrected zone of inhibition assays. Over the temperature range tested, biological activity dropped from excellent to negligible. Biological longevity results showed that controlled release properties of the dressings were significantly reduced by heat treatments above 75 degrees C. These data illustrate nanocrystalline silver sensitivity to heat. Further, it was clear that dressing efficacy is determined by total available soluble silver, not total silver in the dressing. It was determined that the quantity of soluble silver decreased significantly with increased heat treatment temperatures. These results should be considered in developing new nanocrystalline drug delivery systems.

Anti-Bacterial Agents↗
PubMed2006

Antimicrobial activities of silver used as a polymerization catalyst for a wound-healing matrix.

Wound healing is a complex and orchestrated process that re-establishes the barrier and other functions of the skin. While wound healing proceeds apace in healthy individual, bacterial overgrowth and infection disrupts this process with significant morbidity and mortality. As such, any artificial matrix to promote wound healing must also control infecting microbes. We had earlier developed a two-part space-conforming gel backbone based on polyethyleneglycol (PEG) or lactose, which used ionic silver as the catalyst for gelation. As silver is widely used as an in vitro antimicrobial, use of silver as a catalyst for gelation provided the opportunity to assess its function as an anti-microbial agent in the gels. We found that these gels show bacteriostatic and bactericidal activity for a range of Gram-negative and Gram-positive organisms, including aerobic as well as anaerobic bacteria. This activity lasted for days, as silver leached out of the formed gels over a day in the manner of second-order decay. Importantly the gels did not limit either cell growth or viability, though cell migration was affected. Adding collagen I fragments to the gels corrected this effect on cell migration. We also found that the PEG gel did not interfere with hemostasis. These observations provide the basis for use of the gel backbones for incorporation of anesthetic agents and factors that promote wound repair. In conclusion, silver ions can serve dual functions of catalyzing gelation and providing anti-microbial properties to a biocompatible polymer.

Anti-Bacterial Agents↗
PubMed2006

Effect of silver on burn wound infection control and healing: review of the literature.

Silver compounds have been exploited for their medicinal properties for centuries. At present, silver is reemerging as a viable treatment option for infections encountered in burns, open wounds, and chronic ulcers. The gold standard in topical burn treatment is silver sulfadiazine (Ag-SD), a useful antibacterial agent for burn wound treatment. Recent findings, however, indicate that the compound delays the wound-healing process and that silver may have serious cytotoxic activity on various host cells. The present review aims at examining all available evidence about effects, often contradictory, of silver on wound infection control and on wound healing trying to determine the practical therapeutic balance between antimicrobial activity and cellular toxicity. The ultimate goal remains the choice of a product with a superior profile of infection control over host cell cytotoxicity.

Anti-Infective Agents↗
PubMed2005

Studying the size/shape separation and optical properties of silver nanoparticles by capillary electrophoresis.

This paper describes the feasibility of employing capillary electrophoresis (CE) to separate silver particles in nanometer regimes. We have found that the addition of an anionic surfactant, sodium dodecyl sulphate (SDS), to the running electrolyte prevents coalescence of the silver particles during the process, which improves the separation performance; the concentration of SDS required for optimal silver nanoparticle separation is ca. 20 mM. By monitoring the electropherograms using a diode-array detection (DAD) system, we have also investigated the separation of suspended silver nanorods with respect to their shapes. Our results demonstrate that the combination of CE and DAD is a powerful one for the separation and characterization of various silver nanoparticles.

Electrophoresis, Capillary↗
PubMed2004

Use of an oxonol dye in combination with confocal laser scanning microscopy to monitor damage to Staphylococcus aureus cells during colonisation of silver-coated vascular grafts.

The antimicrobial silver-coating of medical prostheses is regarded as a means to reduce the risk of bacterial colonisation after implantation. The effect of a silver-coating of vascular grafts on biofilm formation was assessed in batch cultures of Staphylococcus aureus, using confocal laser scanning microscopy. Total cells in biofilms were analysed by staining with the DNA-binding fluorochrome SYTO 62 and the proportion of damaged cells was quantified with the membrane potential-sensitive dye bis-(1,3-dibutylbarbituric acid) trimethine oxonol. Both the extent of biofilm formation and the proportion of viable biofilm cells were significantly diminished on the surface of the silver-coated vascular grafts compared with uncoated controls, probably due to the antimicrobial activity of silver ions released from the silver-coated graft surface.

Anti-Bacterial Agents↗
PubMed2005

Argyria secondary to ingestion of homemade silver solution.

Argyria is a rare skin disease caused by cutaneous deposition of silver granules in the skin as a result of exposure to silver substrate or ingestion of silver salt. This report describes a patient with generalized argyria caused by ingestion of homemade colloidal silver solution. The patient learned about the uses of the silver solution and its preparation at a convention for "natural medicine."

Argyria↗
PubMed2005

Surface-enhanced Raman activity and stability study of silver films prepared by reduction of Ag+ ions in N,N-dimethylformamide.

A new SERS-active silver film prepared by directly depositing silver nanoparticles on glass is reported. The spontaneous reduction of Ag+ ions in N,N-dimethylformamide (DMF) (in the absence of a protecting agent) leads to the deposition of silver nanoparticles on clean glass surfaces in contact with the solution. The observed optical micrographs and AFM images show that the arrangement of the nanoparticles is inhomogeneous and the particles appear to be closely packed. These films are shown to be excellent substrates for SERS measurements, demonstrating significant enhancement, good stability, and trace detection capability. The SERS enhancement of the silver films with different deposition times was compared and found that the 8-h film gives the largest enhancement ability with an enhancement factor estimated at about 10(9). It is also found that the silver films stored for 80 days in air show no significant degradation in their sensitivity.

Dimethylformamide↗
PubMed2005

Nanocrystalline silver dressings as an efficient anti-MRSA barrier: a new solution to an increasing problem.

The emergence of multi-drug-resistant strains of bacteria represents a particular challenge in the field of wound management. The aim of the current study was to investigate whether nanocrystalline silver dressings possess the physical properties to act as a barrier to the transmission of methicillin-resistant Staphylococcus aureus (MRSA) in the laboratory setting and in a clinical setting. Initially, MRSA suspension and colony culture experiments were performed showing that nanocrystalline silver dressings act as potent and sustained antimicrobial agents, efficiently inhibiting MRSA penetration. Subsequently, a double-centre clinical trial was initiated using nanocrystalline silver dressings as a cover for 10 MRSA colonized wounds in a total of seven patients. By delineating the MRSA load on the upper side of the dressing and the wound bed each time the dressing was changed (i.e. after 1, 24, 48 and 72 h), nanocrystalline silver dressings were found to provide a complete, or almost complete, barrier to the penetration/spread of MRSA in 95% of readings. In addition, 67% of all wound observations showed a decrease in the MRSA load with an eradication rate of 11%. We believe that nanocrystalline silver dressings may become an important part of local MRSA management, with cost benefits to both patients and the healthcare system.

Bandages↗
PubMed2005

Silver-enhanced colloidal gold metalloimmunoassay for Schistosoma japonicum antibody detection.

A silver-enhanced colloidal gold metalloimmunoassay has been proposed for the determination of Schistosoma japonicum antibody (SjAb) in rabbit serum. The adult worm antigen of S. japonicum (SjAg) was adsorbed passively on the walls of a polystyrene microwell and then reacted with the desired SjAb. The colloidal gold-labeled goat anti-rabbit IgG secondary antibody was adsorbed on the walls of the polystyrene microwells through the reaction with SjAb, followed by the silver enhancement process, dissolution of silver metal atoms in an acidic solution, and determination of dissolved silver ions by anodic stripping voltammetry (ASV) at a glassy-carbon electrode. Assay conditions were optimized, including the reaction time of SjAg with SjAb, the interaction of SjAb with the colloidal gold-labeled secondary antibody, the dilution ratio of the colloidal gold-labeled secondary antibody and the silver enhancement time. The integration of the anodic stripping peak current depended linearly on the SjAb logarithmic concentration over the range of 6.4 ng/ml to 100 microg/ml. A detection limit as low as 3.0 ng/ml SjAb was achieved, which was better than the piezoelectric body acoustic wave sensor (detection limit of 7.2 microg/ml) and the renewable amperometric immunosensor (detection limit of 0.36 microg/ml). Rabbit serum samples with various degrees of infection were analyzed, and the results demonstrate that the proposed method meets the requirements of clinical analysis.

Animals↗