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PubMed2006

Efficacy and safety of silver textile in the treatment of atopic dermatitis (AD).

BACKGROUND: Patients with atopic dermatitis (AD) have an increased tendency to develop bacterial skin infections. Colonization with Staphylococcus aureus is known to be a major trigger and might also play a pathophysiological role. Because of their antiseptic action, silver-coated textiles suppress S. aureus colonization and toxin formation, thus damping the inflammatory reaction. OBJECTIVES: To evaluate the clinical effectiveness and safety of a special silver textile in the treatment of patients suffering from acute AD. METHODS: In a randomized phase II monocenter parallel-group comparative study 30 patients were recruited (average age 25.5 years, min. 4 years, max. 70 years) who were affected by AD in an acute phase. During the first study phase from Day 1 to Day 14, 10 patients received a silver textile (Group 1), 10 a silver-free textile (Group 2), and 10 prednicarbate ointment (Group 3). In the second phase from Day 15 to Day 28 all patients wore the silver textile, and during the follow-up period from Day 28 to Day 56 no textiles were used. Prednicarbate ointment was allowed as emergency medication, but ointment consumption was measured. The overall severity of the disease was evaluated using the SCORAD index as the primary efficacy parameter. Secondary parameters included severity of pruritus and the patients' assessment of their disease control (uncontrolled, limited, good or complete). Safety tests included hematology, blood chemistry, urinalysis for silver, and physical examination for silver deposits in the skin and mucous membranes. RESULTS: The initial SCORAD was 61.6 (IQR 26.6, min. 30.6, max. 99.9). At the end of the Study Phase 1 the SCORAD had improved significantly in the patients of Groups 1 (74.6-29.9, p = 0.005) and 3 (57.8-24.0, p = 0.009). During Study Phase 2 healing of eczema continued in Group 1 (SCORAD 29.9-18.1, p = 0.037), was observed in Group 2 (48.2-24.1, p = 0.015), and remained at an improved level in Group 3 (SCORAD 24-23.5). Consumption of prednicarbate ointment (Phase 1, Phase 2, follow-up period, medians are given): Group 1: 135 g, 10 g, 45 g; Group 2: 13 g, 0 g, 0 g; Group 3: 145 g, 30 g, 90 g. Silver textiles reduced the severity of the pruritus (p = 0.031); silver-free textiles (n.s.) and prednicarbate (n.s.) were less effective. No undesired events were observed. CONCLUSION: The elastic silver textile worn directly against the skin led to an impressive improvement of AD and a reduction in the use of prednicarbate ointment.

Adolescent↗
PubMed2005

Detection of silver protein complex injections in the bovine udder using X-ray fluorescence: a preliminary investigation.

To determine the feasibility of using x-ray fluorescence (XRF) to detect the presence of silver in the mammary gland of dairy cows injected with mild silver protein suspension. The XRF spectroscopy was conducted on cadaver udders with and without mild silver protein injected. Spectral analysis was performed in order to determine the amplitude of the silver K-alpha peak that was detected. By comparing the amplitude of the K-alpha peak to the background, a minimum time of collection was determined, as a measure of the time required to observe a silver signal that is significantly non-zero. The minimum detection time required for evidence of injected silver suspension was calculated to be 2.8 +/- 0.2 s. Even with an additional requirement that the net signal exceed 50 counts, the clear indication of the presence of silver will be observed within 4 min of interrogation. X-ray fluorescence spectroscopy was shown to be a viable method for the detection of injected silver protein in cadaver mammary glands of dairy cows. While these findings are promising, further studies must be conducted to investigate the time dependence of the silver signal when diffusion, absorption, and redistribution are involved, under conditions that better mimic those encountered at an exhibition. This technique, used in conjunction with screening ultrasound examinations, has the potential to confirm sites of injection of silver compounds.

Animals↗
PubMedDate not supplied

Biocompatibility of silver-coated peritoneal dialysis catheter in a porcine model.

OBJECTIVE: Previous studies have shown that silver formulations coated onto implantable materials retard bacterial colonization and reduce the incidence of catheter-related infections. The objective of this study was to assess the histologic effects of sputter-coated silver/ silicone implants on host tissue. DESIGN: Sputter silver-coated silicone peritoneal dialysis catheter segments with and without Dacron cuffs were implanted in the subcutaneous fat and muscle in 4 pigs. Noncoated implants served as controls. The specimens were retrieved at 1, 2, 3, 4, 7, 8, 9, 10, 12, and 27 weeks. EXPERIMENTAL ANIMALS: Four 6-week-old male Yorkshire-Landrace pigs (5-6 kg) were used. MAIN OUTCOME MEASURES: Histologic parameters evaluated included the degree of inflammation, the number of giant cells, the extent of silver particulate inclusions, and the thickness of the capsules. All specimens were evaluated by a single blinded pathologist. Microbiologic analyses were also performed. RESULTS: The silver-coated catheters were associated with less inflammation than were the noncoated catheters, both in fat and muscle (p = 0.04). The number of giant cells was also lower around the silver-coated than the non-coated catheters, which were implanted in subcutaneous fat (p < 0.05). Particulate inclusions compatible with silver or silver oxide were observed only in tissue around silver-coated implants (p < 0.0001). The thickness of the capsules and the extent of the inflammatory zones were not significantly different. There was no evidence of infection-related changes. CONCLUSIONS: These data suggest that the sputter silver coating does not act as a significant tissue irritant.

Animals↗
PubMed1996

Immunogold silver staining for light microscopy.

The immunogold silver staining method (IGSS) is widely used as a sensitive and specific immunohistochemical visualisation technique. IGSS involves the specific deposition of metallic silver at the site of immunogold labelling and provides a means of visualisation at low magnification by light or electron microscopy. Silver developers for IGSS rapidly deposit metallic silver only at the site of heavy metals, including gold and silver, because of their catalytic activity. The developing solution contains the silver ions and reducing agent necessary for this reaction. Using different silver salts as ion donors and by selecting an appropriate temperature and pH, visible amounts of silver can be deposited in a few minutes at the site of colloidal gold labelling while little non-specific background deposition occurs. Inclusion of protective colloids in the solution can also be used to control the reaction. Although studies of the chemical basis of silver deposition around unlabelled colloidal gold date back to 1939, immunogold enhancement by silver was established in 1983. The IGSS method evolved from the combination of disparate photographic, histochemical and immunogold techniques which have been effectively combined and optimised over the last 10 years to provide a visualisation system which is well suited to many immunohistochemical studies.

Humans↗
PubMed2001

A comparative study of third-order nonlinear optical properties of silver phenylacetylide and related compounds via ultrafast optical Kerr effect measurements.

A comparative study of the third-order nonlinear optical properties, via the newly developed heterodyned optical Kerr effect (OHD-OKE) measurements, of silver phenylacetylide and related compounds is reported. [AgC[triple bond]CC(6)H(5)](n) (1) was found to exhibit efficient third-order nonlinear optical susceptibility chi((3)) of 2.4 x 10(-14) esu, and second hyperpolarizability gamma of 9.07 x 10(-32) esu. These results are compared with those of two related silver phenylacetylide compounds, namely, a double salt, (silver phenylacetylide).(silver tert-butylthiolate) [AgC[triple bond]CC(6)H(5).AgS(t-C(4)H(9))](n) complex (2), and a cluster, triphenylphosphine silver phenylacetylide tetramer, [(C(6)H(5))(3)PAgC[triple bond]CC(6)H(5)](4) (3), as well as that of the related organic polymer polyphenylacetylene (4). These four compounds represent different types of phenylacetylide derivatives: 1 is an organometallic polymer, 2 a polymeric double salt, 3 a discrete metal cluster, and 4 an organic polymer. It was found that the third-order optical nonlinear response was enhanced by the incorporation of silver d electrons into the delocalized conjugated organic pi system, and its magnitude is highly dependent upon the extent of the pi delocalization. Specifically, the relative magnitudes of chi((3)) and gamma follow the order silver phenylacetylide polymer (1) > (silver phenylacetylide).(silver tert-butylthiolate) double salt (2) > polyphenylacetylene polymer (4) > tetrameric (triphenylphosphine silver phenylacetylide)(4) cluster (3). The observed trend may be attributed to the decreasing length of pi conjugation. It is interesting to note that the incorporation of Ag(I) into the polymeric framework of polyphenylacetylene enhances the chi((3)) by 25-fold for the same degree of polymerization (n = 7). The signs of chi((3)) and gamma, which are related to the response mechanisms, were found to be solvent dependent.

Journal Article↗
PubMed2004

Electrochemical deposition of silver in room-temperature ionic liquids and its surface-enhanced Raman scattering effect.

The use of room-temperature ionic liquids (RTILs) as media for electrochemical application is very attractive. In this work, the electrochemical deposition of silver was investigated at a glassy carbon electrode in hydrophobic 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) and hydrophilic 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) RTILs and in KNO3 aqueous solution by cyclic voltammetric and potentiostatic transient techniques. The voltammograms showed the presence of reduction and oxidation peaks associated with the deposition and dissolution of silver from AgBF4 in both BMIMPF6 and BMIMBF(4), resembling the redox behavior of AgNO3 in KNO3 aqueous solution. A crossover loop was observed in all the cyclic voltammograms of these electrochemical systems, indicating a nucleation process. From the analysis of the experimental current transients, it was shown that the electrochemical deposition process of silver in these media was characteristic of 3D nucleation with diffusion-controlled hemispherical growth, and the silver nucleation closely followed the response predicted for progressive nucleation in BMIMPF6 and instantaneous nucleation in KNO3 aqueous solution, respectively. Compared with these two cases, the electrochemical deposition of silver in BMIMBF4 deviated from both the instantaneous and progressive nucleation models, which could be controlled by mixed kinetics and diffusion. On the basis of the experimental results, it was shown that parameters such as viscosity and water miscibility of RTILs would affect the electrodeposition behavior of silver. Atom force microscopy was employed to probe the surface morphology of the silver deposit, and it showed that the shining electrodeposit of silver was fairly dense and separate nanoclusters of <100 nm were in evidence, corresponding to an island growth model. The strongly enhanced Raman scattering from the monolayer film of 4-mercaptobenzoic acid demonstrated that as-prepared silver nanoparticular film was surface-enhanced Raman scattering (SERS) active. The enhancement factor was calculated to be up to 9.0 x 10(5) and 1.0 x 10(6) for the silver film obtained in BMIMPF6 and BMIMBF4 RTILs, respectively.

Journal Article↗
PubMed2006

Endocrine evidence that silvering, a secondary metamorphosis in the eel, is a pubertal rather than a metamorphic event.

Silvering (transition from yellow to silver eel) has been traditionally considered as a metamorphosis in view of the numerous morphological, physiological and behavioral changes preparing the eel for the oceanic migration. However, some changes, such as increases in gonad weight and steroidogenesis, suggest that silvering could also be considered as a pubertal event. In order to assess which endocrine axis may be involved in the induction of silvering, we compared the profiles of pituitary and peripheral hormones during the transition from yellow to silver female eels. A strong activation of the gonadotropic axis was shown during silvering. Follicle-stimulating hormone (FSH) mRNA levels increased during the early stages of silvering, followed by a later increase in luteinizing hormone (protein and mRNA) levels. In addition, plasma levels of sexual steroids (estradiol, E2; testosterone, T, and 11-ketotestosterone) and of vitellogenin significantly increased. In contrast, thyrotropin mRNA levels did not change and no or weak variations in plasma thyroid hormones were observed, indicating no or moderate change of the thyrotropic axis during silvering. Similarly, the somatotropic axis was not activated, as shown by pituitary growth hormone expression (protein and mRNA) and plasma levels. In addition, we studied the effects of chronic treatments of female yellow eels with thyroid hormone (thyroxine, T4) and sex steroids (T and E2) on biometrical parameters characteristics of silvering. T induced an increase in eye size and a reduction of digestive tract, whereas T4 and E2 had no effect. These hormonal profiles and experimental data lead to the conclusion that eel silvering should be considered as an onset of puberty rather than a 'genuine' metamorphosis.

Animals↗
PubMed2006

Biomimetics of silver nanoparticles by white rot fungus, Phaenerochaete chrysosporium.

Extracellular synthesis of silver nanoparticles by a white rot fungus, Phaenerochaete chrysosporium is reported in this paper. Incubation of P. chrysosporium mycelium with silver nitrate solution produced silver nanoparticles in 24h. These silver nanoparticles were characterized by means of UV-vis spectroscopy, X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The synthesized silver nanoparticles absorbed maximum at 470 nm in the visible region. XRD spectrum of the silver nanoparticles confirmed the formation of metallic silver. The SEM characterization of the fungus reacted on the Ag+ indicated that the protein might be responsible for the stabilization of silver nanoparticles. This result was further supported by the TEM examination. Though shape variation was noticed, majority of the nanoparticles were found to be of pyramidal shape as seen under TEM. Photoluminescence spectrum showed a broad emission peak of silver nanoparticles at 423 nm when excited at 350 nm. Apart from eco-friendliness, fungus as bio-manufacturing unit will give us an added advantage in ease of handling when compared to other classes of microorganisms.

Ascomycota↗
PubMed1995

Mechanism of irreversible inactivation of phosphomannose isomerases by silver ions and flamazine.

Silver ions and silver-containing compounds have been used as topical antimicrobial agents in a variety of clinical situations. We have previously shown that the enzyme phosphomannose isomerase (PMI) is essential for the biosynthesis of Candida albicans cell walls. In this study, we find that PMI can be inhibited by silver ions. This process is shown to be irreversible, and is a two-step process, involving an intermediate complex with a dissociation constant, Ki, of 59 +/- 8 microM, and a maximum rate of inactivation of 0.25 +/- 0.04 min-1 in 50 mM Hepes buffer, pH 8.0 at 37 degrees C. The enzyme can be protected against this inactivation by the substrate mannose 6-phosphate, with a dissociation constant of 0.31 +/- 0.04 mM, close to its Km value. Flamazine (silver sulfadiazine) is a silver-containing antibiotic which is used clinically as a topical antimicrobial and antifungal agent. We compared the ability of silver sulfadiazine and two other silver-containing compounds to irreversibly inactivate C. albicans PMI. The addition of the organic moiety increased the affinity of the compounds, with silver sulfadiazine showing a Ki of 190 +/- 30 nM. In all cases, the maximum inhibition rate was similar, implying a similar rate-determining step. Silver sulfadiazine does not inhibit Escherichia coli PMI, and this suggests a role of the only free cysteine, Cys-150, in the inactivation process. To confirm this, we mutated this residue to alanine in C. albicans PMI. The resultant Cys150 --> Ala mutant protein showed similar Vm and Km values to the wild-type enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine↗
PubMed1993

Effect of preinduction of metallothionein on tissue distribution of silver and hepatic lipid peroxidation.

Silver ion causes a number of toxic effects, it decreases the activities of lactate dehydrogenase and glutathione peroxidase, and the peroxidation of membrane lipids. Silver ions complex strongly to sulfhydryl groups and the effects of preinduction of metallothionein, a sulfur-rich protein, on silver administration in rats were examined. The preinduction of metallothionein decreased the mortality of mice following silver administration. A major portion of the incorporated silver in the liver was bound to the basal membrane and cellular components, and the distribution of silver into cytosol was small. The preinduction of metallothionein decreased the amount of bound silver in the membrane and increased the distribution of silver in the cytosol; in addition, it depressed silver-induced lipid peroxidation in liver.

Animals↗
PubMed2002

[Time resolution spectrum measurements of the process of photon acting on the silver halide materials].

The silver halide material is a very important optical information material. Silver halide material plays a very imperative role in the development of the information science and technology. The time characters of the photon action process determine the quality of the silver halide material to a great degree. We adopt the microwave absorption technology to measure the time characters of the process of the photon acting on silver halide material. A sample of the silver halide material is inserted into a microwave resonant cavity. With the excitation of excimer laser, photogenerated charge carriers are created in the silver halide material. The generation of the photogenerated charge carriers changes the dielectric function of the silver halide material. Therefore, the change of the dielectric function embodies the information of the time characters of the photogenerated change carries. At the same time, the change of the dielectric function results in an alteration of the cavity quality factor. This change leads to a reflected microwave. The reflected microwave contains the information of the time characters of the photon action process. Through the measurement of the reflected microwave, we can obtain the time resolution spectrum of the process of the photon acting on the silver halide material and study the time characters of the photon action process. The time resolution spectra of the process of the photon acting on various silver halide materials were obtained in our experiments. We analyzed the time characters of photon acting on the black-and-white film, color film and X-ray film.

Absorption↗
PubMed2000

Efficacy of silver-coated fabric to prevent bacterial colonization and subsequent device-based biofilm formation.

Efficacy of silver-coated poly(ethylene terephthalate) to prevent bacterial attachment and subsequent infection was quantified in vitro, in both batch- and flowing-fluid experiments. Kinetic analysis of batch suspended cell cultures of Staphylococcus epidermidis (SE), at various growth-limiting nutrient concentrations, in the absence of any fabric, indicated a maximum culture growth rate constant micro(max) = 0.78 +/- 0.02 h(-1). Batch experiments for Control fabric samples indicated that SE cultures exhibited about the same suspended cell growth rate (0.72 +/- 0.02 h(-1)) as observed in batch suspended cultures without fabric. Suspended SE cultures in the presence of silver-coated fabric grew at a considerably lower rate, 0.15 +/- 0.01 h(-1), indicating the inhibitory effect of Ag(+2) ion released from the fabric. Growth rates of suspended SE cultures were 5-6 times higher in the fluid phase in contact with the Control fabric compared to cultures exposed to silver-coated fabric. Maximum suspended cell concentrations attained at time = 24 h were 1-2 orders of magnitude higher for Control fabrics vs. silver-coated fabric. In all batch colonization experiments, both live and dead SE bacterial cells accumulate on the surfaces of both silver-coated and Control fabrics. Adherent viable SE cells accumulated to 1-2 orders of magnitude more ( approximately 5 x 10(+8) cells/cm(2)) on Control fabric than SE cells on the silver-coated fabric ( approximately 1.1 x 10(+6) cells/cm(2)), respectively. Between 70-95% SE cells on the Control fabric were viable, while on the silver-coated fabric samples, at 24 h, viable cells were less than 10% of the adherent community (i.e., greater than 90% nonviable cells). In flow cell colonization experiments, SE cells accumulated on Control fabric to a maximum adherent cell concentration of 6 x 10(+7) - 8 x 10(+7) cells/cm(2) by 24 h with the proportion of viable cells remaining relatively constant at 76% throughout an experiment. Both noninvasive microscopic enumeration and destructive assays gave the same results for adherent cell numbers. Using silver-coated fabric, total cells numbers (live + dead) reached a level of approximately 1.1 x 10(+7) - 3.0 x 10(+7) cells/cm(2) after about 6 h and remained constant. However, while the proportion of viable cells initially on the surface was 63-75%, this fraction dropped continuously during each experiment to less than 6% viable cells at 24 h. Regardless of the criteria, the number of viable or nonviable cells attached to silver-coated fabric were significantly lower than on Control fabric.

Bacteria↗
PubMedDate not supplied

Effects of a 2.5-mg silver acetate lozenge on initial and long-term smoking cessation.

BACKGROUND: Silver acetate over-the-counter products, such as gum, lozenge, and spray, produce an aversive metallic taste when combined with cigarette smoke. Hence, they hold promise of serving as an effective smoking deterrent, one that may be used on a self-help basis. PROCEDURE: Five hundred adult smokers, male and female, were assigned randomly to one of two experimental conditions, 2.5-mg silver acetate lozenge and placebo lozenge. A double-blind study of the effects of a 2.5-mg silver acetate lozenge on initial (3 weeks) and long-term (12 months) smoking cessation was carried out. RESULTS: About 90% of the subjects (n = 500) reported using the lozenge (silver acetate or placebo) for smoking cessation, and they used about five lozenges per day. Over 70% of the quitters (n = 70) reported using the lozenge on an as-needed basis for relapse prevention. The overall objectively verified quit rates for subjects assigned to the silver acetate and placebo conditions at Visit 3 (3 weeks) were 17% (n = 42) and 11% (n = 28), respectively, a difference which approached statistical significance (P = 0.071). When the analysis was restricted to subjects who used the product, a statistically significant difference (P < 0.05) in initial smoking cessation emerged (26%, n = 37 vs 16%, n = 23) for subjects assigned to the silver acetate and placebo conditions. At 12 months follow-up, 26% (n = 11) of initial quitters in the silver acetate condition and 32% (n = 9) of the quitters in the placebo condition were abstinent. This difference was not statistically significant. CONCLUSIONS: The study demonstrated modest efficacy for the effect of the 2.5-mg silver acetate lozenge on initial smoking cessation for the subset of subjects who used the product as recommended. We failed to demonstrate efficacy of the lozenge for long-term relapse prevention. Additional research on the efficacy of the 2.5-mg silver acetate lozenge and long-term abstinence in general appears warranted.

Acetates↗
PubMed1987

Silver affects viability and structure of cultured mouse peritoneal macrophages and peroxidative capacity of whole mouse liver.

The effects of silver on cultured mouse peritoneal macrophages were examined by estimation of cell survival and by light and electron microscopy. Addition of silver lactate to the culture medium at final concentrations of 40 and 80 microM resulted in coagulation necrosis and rapid cell death. At lower concentrations cell structure appeared normal. However, the rate of cell death at 20 microM silver lactate was increased as compared to controls. Silver, visualized by physical development/autometallography, was invariably located in lysosomes. The production of malondialdehyde in mouse liver of silver-treated mice as compared to controls was also examined. This lipid peroxidation product had increased to the same amount in animals treated with silver for either 3 days or with only one silver injection 4 h before examination. This study has demonstrated that silver affects viability and structure of cultured macrophages, possibly due to induction of lipid peroxidation, as demonstrated to occur in the liver of silver-exposed mice.

Animals↗
PubMed1987

Autometallography: tissue metals demonstrated by a silver enhancement kit.

In biological tissue, minute accumulations of gold, silver, mercury and zinc can be visualized by a technique whereby metallic silver is precipitated on tiny accumulations of the two noble metals, or on selenites or sulphides of all four metals. In the present study a silver enhancement kit, primarily intended for the amplification of colloidal gold particles, has been used to demonstrate these catalytic tissue metals. Sections from animals exposed intravitally to aurothiomalatate, silver lactate, mercury chloride, sodium selenite or perfused with sodium sulphide were subjected to a commercial silver enhancement kit (IntenSE, Janssen Pharmaceutica). It was found that the kit performs adequately to the silver lactate gum arabic developer and to the photographic emulsion technique. The kit can be used as a silver enhancement medium for the demonstration of zinc by the Neo-Timm and selenium methods and for demonstration of gold, silver, and mercury in tissues from animals intravitally exposed to these metals. It can also be used for counterstaining silver treated osmium fixed tissues embedded in plastic.

Animals↗
PubMed1983

Neuronal accumulation of silver in brains of progeny from argyric rats.

Using a photochemical method silver was demonstrated in the brains of 1-, 14-, and 45-day-old rats which had been exposed to silver on gestational days 18 and 19. In the brain tissue of new-born rats, silver was found in the lysosomes of neurons and astroglia. Minor changes in the anatomic distribution of silver were observed between days 1 and 45. The pattern seen at day 45 was identical to that observed in silver-exposed adults. At day 1, the choroid plexus and meninges were heavily loaded with silver both intra- and extracellularly. In particular, macrophage-like cells of the meningeal spaces contained large amounts of silver. In these structures, the silver had virtually disappeared by day 45. Silver was always seen in basement membranes of the cerebral vessels.

Animals↗
PubMed2000

[Antimicrobial efficacy of a silver layer on hydrogel lenses] Citation].

BACKGROUND: The high standard of hygiene required in using contact lenses requires regular sterilization, for which the application of a hydrogen peroxide system or storage in liquids containing antimicrobial agents are regarded as the most effective procedures. An approach to avoiding contamination could be to provide the lenses themselves with antimicrobial properties. For this purpose contact lenses equipped with a silver layer were examined for their effect on bacteria. MATERIALS AND METHODS: The antimicrobial efficacy of a silver layer on Weflex 55 hydrogellenses (watercontent 55%, nonionic) was investigated. The lenses were incubated at 37 degrees C for 1 h in suspensions (10(8) CFU/ml) with Pseudomonas aeruginosa or Staphylococcus aureus and were rinsed afterwards. The detachment of the adherent bacteria took place by shaking the lenses in the presence of glass beads (diameter 0.5 mm). Samples of these suspensions were taken, and microbial counts were performed before and after incubation of the contaminated lenses for 6 h and 24 h in a sterile solution of sodium chloride (0.9%, w/v). RESULTS: Lenses with a silver layer showed markedly fewer test organisms than did unprepared lenses. However, this effect was detectable only when the contaminated lenses were kept in sodium chloride solution (0.9%) for several hours. After incubation for 67 at 25 degrees C the microbial numbers of P. aeruginosa were diminished by about 4 log steps, and those of S. aureus by about 1 log step. Particularly in the case of P. aeruginosa the antimicrobial property of the silver layer was very effective. The microbial numbers of this species, which can cause serious infections of the eyes, were reduced after 24 h by more than 6 log steps. However, S. aureus showed a reduction of only 1.5 log steps. These results reflect the antimicrobial effect of silver ions which are dissolved from depots in the surfaces of the lenses only in traces because of their low dissolution properties. CONCLUSIONS: These first investigations of preserved contact lenses indicate a new possibility for reducing lens-induced infections of the eyes. Due to the weak efficacy against the gram-positive species S. aureus a silver layer probably cannot replace other sterilization procedures completely, but it may represent an additional protection from contamination. Side effects to the eyes due to the negligible toxicity of oligodynamics silver concentrations, such are known to occur with high silver concentrations, should be not expected, but possible allergic reactions caused by the silver-ions should be investigated.

Anti-Bacterial Agents↗
PubMed1994

Potent and reversible interaction of silver with pure Na,K-ATPase and Na,K-ATPase-liposomes.

The Na,K-ATPase (EC 3.6.1.37) is the receptor for cardioactive steroids, the only specific inhibitors known at the present time for this unique membrane bound transport system. We report here that silver is the most rapid and potent inhibitor of isolated Na,K-ATPase ever described. Inhibition of Na,K-ATPase activity by silver is immediate and strikingly distinct from other inhibitors: addition of 1 mM of cysteine or DMPS reactivates the silver blocked-enzyme immediately. The results reveal that silver interacts with Na,K-ATPase and inhibits differently by an on-off mechanism involving most likely a few critical sulfhydryl groups. Inhibition of Na-K transport by silver has been demonstrated also in an artificial membrane, e.g., in liposomes reconstituted with pure Na,K-ATPase performing active transport. Silver inhibits the active 86Rb transport mediated by the pure Na,K-ATPase molecule. The Na,K-ATPase contained in the liposomes was labeled specifically with 110mAg and appeared to bind two silver ions. Taken together, the results show that the mechanism of silver interaction with Na,K-ATPase might be different from other metals, for instance, mercury. The unique action mechanism of silver suggests a fundamental role of a few critical sulfhydryl groups for Na,K-transport.

Animals↗