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At least 109 records · Page 6Linked to original sources
PubMed1997

Age-related changes of sulphide-silver staining in the rat hippocampus.

The influence of ageing on sulphide-silver positive zinc stores was assessed in the stratum radiatum of the CA1-CA3 sub fields of the rat hippocampus and in the molecular layer of the dentate gyrus using a silver amplification histochemical technique associated with microdensitometry. The volume of areas examined for microdensitometry was evaluated as well by quantitative image analysis. Male Sprague-Dawley rats aged 3 months (considered to be young), 12 months (considered to be adult) and 24 months (considered to be old) were used. Microdensitometric analysis of values of sulphide-silver staining corrected for the volume of hippocampal areas investigated revealed no age-dependent changes of staining in the CA1 sub field of the hippocampus. In the CA2 sub field a decrease of sulphide-silver staining was noticeable in aged rats in comparison with younger cohorts. A progressive reduction in the intensity of sulphide-silver staining was observed in the CA3 sub field of the hippocampus. In the molecular layer of the dentate gyrus, the intensity of staining was decreased in adult and old rats in comparison with young animals. These findings indicate a different sensitivity to ageing of histochemically detectable zinc stores of rat hippocampus. The possibility of a specific sensitivity to senescence of different zinc-containing pathways of the hippocampus is discussed.

Aging↗
PubMed1998

Effects of pulsed Nd:YAG laser irradiation on root canal wall dentin with different laser initiators.

The effects of pulsed Nd:YAG laser irradiation with different laser initiators on the permeability and ultrastructure of the root canal wall dentin were investigated in vitro. Forty extracted human single-rooted teeth were randomly assigned to four groups. Group 1 teeth were not lased as a control. Group 2 specimens received four 10-s duration laser exposures for a total exposure of 40 s/canal. In group 3 specimens, the root canals were painted with black ink and then lased by the same method as group 2 teeth. In group 4 specimens, root canals were treated with 38% Ag(NH3)2F and then lased by the same method as group 2 teeth. Laser parameters were set at 2 W, 20 pps. After being placed in 0.6% rhodamine B solution for 48 h, the teeth were sectioned for study by stereoscope and scanning electron microscopy. Statistical analysis showed there were significant differences (p < 0.05) in dentin permeability in the apical areas between groups 3 and 1, 4 and 1, and 4 and 2. Scanning electron microscopic examination showed that laser treatment alone had no obvious effects on the root canal wall. The root canal surfaces prepared for by laser irradiation with black ink or 38% Ag(NH3)2F revealed melting, smear layer evaporation, and open dentinal tubules. Black ink was more effective than 38% Ag(NH3)2F as a Nd:YAG laser initiator.

Dental Pulp Cavity↗
PubMed1998

Radiopaque poly(2-hydroxyethyl methacrylate) particles containing silver iodide complexes tested on cell culture.

Silver iodide complexes have been used as an effective radiopacifying agent to prepare radiopaque poly(2-hydroxyethyl methacrylate) (poly(HEMA)) particles. Incorporation of silver iodide complexes inside the poly(HEMA) particles was achieved by first swelling particles in potassium iodide solution and precipitating the silver iodide complexes using a 30 wt% solution of silver nitrate. The dry particles contained 15 wt% of silver iodide complexes. Particles were easily monitored using a standard imaging technique based on X-ray absorption. Toxicity of the particles has been determined in in vitro experiments on a cell culture. As no inhibition of growth of cells surrounding the particles was observed, they can be considered non-toxic.

Biocompatible Materials↗
PubMed1998

A simplified procedure for the physical development of the sulphide silver method to reveal synaptic zinc in combination with immunocytochemistry at light and electron microscopy.

The pool of zinc present in excitatory synaptic terminals in normal and pathological conditions (for instance the status epilepticus induced by kainic acid) can be stained by a silver sulphide method followed by physical development of the insoluble zinc-sulphide complexes. In this study we applied a previously described simple and rapid developing procedure that reveals synaptic zinc, to the study of normal and pathological hippocampi and combined it with pre and postembedding immunocytochemical methods to detect different antigens. Normal and kainic acid-treated rats were perfused with fixative solutions containing sodium sulphide and 50 microm-thick vibratome sections of the hippocampi were incubated in a commercial developing solution (IntenSE M, Amersham). The developed vibratome sections were then (1) mounted for light microscopy or osmicated and epon-embedded for electron microscopy; or (2) processed for the preembedding immunoenzymatic detection of various antigens (GABA, parvalbumin, calbindin) with light and electron microscopy. Thin sections from epon-embedded samples were also processed for the postembedding immunogold localization of glutamate. This very simple and rapid procedure gives rise to zinc-specific staining, comparable to that obtained with classical developing methods and good preservation of both antigenicity and ultrastructure. It is therefore possible to detect, in the same thick or thin section, zinc reaction product and different antigens.

Animals↗
PubMed1999

Efficacy of topical silver against fungal burn wound pathogens.

BACKGROUND: Fungal infections of burn wounds have become an important cause of burn-associated morbidity and mortality. The nature of fungal infections dictates aggressive treatment to minimize the morbidity associated with these infections. Persons with large total body surface area burns are particularly susceptible to fungal infections and are treated in such a manner as to minimize their risk of infection. METHODS: This study examined the in vitro fungicidal efficacy of a variety of different topical agents. By placing fungal inocula in contact with mafenide acetate, silver nitrate, silver sulfadiazine, and a nanocrystalline silver-coated dressing, we determined the kill kinetics of these topical agents against a spectrum of common burn wound fungal pathogens. RESULTS: The topical antimicrobials that were tested demonstrated varying degrees of efficacy against these pathogens. CONCLUSION: The nanocrystalline silver-based dressing provided the fastest and broadest-spectrum fungicidal activity and may make it a good candidate for use to minimize the potential of fungal infection, thereby reducing complications that delay wound healing.

Antifungal Agents↗
PubMed2000

Bioaccumulation and localization of exogenous cadmium in a teleost by electron microscopy (TEM) and its specific quantitation by electron probe X-ray microanalysis (EPMA).

A cadmium bioconcentration study was carried out in a fresh water teleost, Colisa fasciatus, to study the bioaccumulation kinetics and fate of exogenous cadmium (Cd) in biological tissues. Study shows that on exposure of the fish to a sublethal concentration of cadmium in test water, Cd uptake results in its bioconcentration in gills, liver and muscle tissues. To explore whether the accumulated Cd reaches the membranes or inside the cells, transmission electron microscopy (TEM) of the thin sections of tissues was done after histochemical localization of Cd in cells by modified SST method. TEM studies of sections of gills, liver and muscle tissues showed the deposits of exogenous Cd (visualized as dense clouds) in biological cells. This suggests the presence of free or loosely bound Cd on the membranes and inside the cells, which in the presence of Na2S is converted into insoluble metal sulfides. Electron probe X-ray microanalysis (EPMA) studies confirmed the presence of Cd on the membrane surface as well as inside the cells of bioindicator organs suggesting involvement of membrane transport of exogenous Cd inside the cells and its deposition as loosely bound insoluble metal complexes.

Animals↗
PubMed1997

Plasmids and bacterial resistance to biocides.

Plasmid-encoded bacterial resistance to antibiotics and to anions and cation (including important mercurial and silver compounds) has been widely studied. Plasmid-mediated resistance to organic cationic agents which are important biocides has been described for chlorhexidine and quaternary ammonium compounds (and also for the less important acridine, diamidines and ethidium bromide) in antibiotic-resistant Staphylococcus aureus and Staph. epidermidis strains. Plasmids may also encode reduced biocide susceptibility of Gram-negative bacteria, but intrinsic resistance is likely to be of greater significance. Antibiotic resistance and biocide resistance may be linked but this is not always found clinically.

Anti-Infective Agents, Local↗
PubMed2000

Disinfection kinetics: a new hypothesis and model for the tailing of log-survivor/time curves.

A new hypothesis for the understanding of chemical disinfection, which we have termed the Intrinsic Quenching hypothesis, is presented. This mechanistic treatment of disinfection kinetics is based on the hypothesis that the biocide concentration may not be in vast excess over the microbes, as is normally assumed. A mathematical model was developed and found to be useful in describing the observed kinetics of several disinfectants. The model suggested that the reason for the observation of non-linear, log-survivor curves was due to the ability of the microbes, in clean, soil-free conditions, to intrinsically quench the bulk concentration of biocide.

Disinfectants↗
PubMed1999

Silver-based crystalline nanoparticles, microbially fabricated.

One mechanism of silver resistance in microorganisms is accumulation of the metal ions in the cell. Here, we report on the phenomenon of biosynthesis of silver-based single crystals with well-defined compositions and shapes, such as equilateral triangles and hexagons, in Pseudomonas stutzeri AG259. The crystals were up to 200 nm in size and were often located at the cell poles. Transmission electron microscopy, quantitative energy-dispersive x-ray analysis, and electron diffraction established that the crystals comprise at least three different types, found both in whole cells and thin sections. These Ag-containing crystals are embedded in the organic matrix of the bacteria. Their possible potential as organic-metal composites in thin film and surface coating technology is discussed.

Crystallization↗
PubMed2002

Bis(trimethylphosphine)silver(I) hexafluorophosphate.

In the title two-coordinate silver compound, [Ag(C(3)H(9)P)(2)]PF(6), the cation has crystallographically imposed mirror symmetry, and approximates very closely to 3m (D(3d)) symmetry with fully staggered methyl groups in the solid state. The Ag atom has a nearly linear coordination geometry, with a P[bond]Ag[bond]P angle of 178.70 (4) degrees. The Ag[bond]P bond lengths are 2.3746 (12) and 2.3783 (12) A, which are significantly longer than the Au[bond]P bond length of 2.304 (1) A in the analogous two-coordinate gold cation. The lack of intramolecular steric effects within the present cations containing trimethylphosphine (cone angle 118 degrees), compared with those in known cations containing trimesitylphosphine (cone angle 212 degrees), provides a better comparison of M[bond]P distances and thus more conclusive evidence that Au really is smaller than Ag.

Journal Article↗
PubMed2004

First bent form for the hydroxo-bridged cis-diammineplatinum(II) dimer [Pt(2)(NH(3))(4)(micro-OH)(2)](ClO(4))(2).

The third crystal structure containing the hydroxo-bridged cis-diammineplatinum(II) dimer has been determined for a perchlorate salt of the complex, [Pt(2)(NH(3))(4)(micro-OH)(2)](ClO(4))(2). However, the dinuclear cations in the nitrate and the carbonate salts, [Pt(2)(NH(3))(4)(micro-OH)(2)](NO(3))(2) [Faggiani, Lippert, Lock & Rosenberg (1977). J. Am. Chem. Soc. 99, 777-781] and [Pt(2)(NH(3))(4)(micro-OH)(2)](CO(3)).H(2)O [Lippert, Lock, Rosenberg & Zvagulis (1978). Inorg. Chem. 17, 2971-2975], were reported to possess a nearly planar geometry. The cation in the title perchlorate salt has been found to possess an exceptional bent form in which two Pt coordination planes within the dimer are tilted at an angle of 151.7 (1) degrees to one another. The diplatinum entity has a syn orientation with regard to the conformation of two hydroxo bridges, in part due to the one-dimensional hydrogen-bonding network achieved in the crystal structure. DFT MO investigations have also been carried out to reveal that the planar-bent selection could be induced by the anti-syn selection at the H(hydroxo) atoms. Comparison has also been made between the geometrical features of the three salts from the viewpoint of the orientation of H(hydroxo) atoms.

Carbonates↗
PubMed1988

Inhibition of bacterial colonization by antimicrobial agents incorporated into dental resins.

The antimicrobial activity of several chemical agents was determined by incorporating these agents into dentine adhesive resin and following the colonization of Streptococcus mutans on the surfaces of the resin and culture vessel, as well as in the surrounding medium, by optical density measurements. It was found that sodium fluoride and dodecylamine, an organic amine, exhibited excellent antimicrobial properties. These chemicals not only inhibited bacterial growth completely but also seemed to reduce the adhesion of the bacteria to the resin surface. A silver compound, protargin, was mildly effective in inhibiting growth of S. mutans. Copper oxide and chelating acids such as vanillic acid, syringic acid, and ethylenediamine-n, n' diacetic acid (EDDA) were not effective as antimicrobial agents against S. mutans.

Amines↗
PubMed1976

Antifungal properties of electrically generated metallic ions.

A qualitative and quantitative investigation was undertaken to study the susceptibility of unicellular eucaryotic organisms (yeasts) to metallic cations generated by low levels of direct current. Results were characteristic of effects obtained previously using clinical and standard bacteria test organisms. The present study demonstrated that anodic silver (Ag(+)) at low direct currents had inhibitory and fungicidal properties. Broth dilution susceptibility tests were made on several species of Candida and one species of Torulopsis. Growth in all isolates was inhibited by concentrations of electrically generated silver ions between 0.5 and 4.7 mug/ml, and silver exhibited fungicidal properties at concentrations as low as 1.9 mug/ml. The inhibitory and fungicidal concentrations of electrically generated silver ions are lower than those reported for other silver compounds.

Antifungal Agents↗
PubMed2006

Hygienic relevance and risk assessment of antimicrobial-impregnated textiles.

The antimicrobial impregnation of textiles is intended to provide protection of textiles against microbial corrosion, prevention of malodor or prophylaxis and therapy of infections, respectively. For every biocidal product a careful risk assessment for humans and the environment has to be performed. The advantage of antimicrobially active textiles has to be documented for every agent as well as for every application, and a balance has to be found between a textile's quality rating and the potential risks, e.g. sensitization, disturbance of the ecology of the skin, toxic side effects by means of systemic absorption, cytotoxicity, genotoxicity, carcinogenicity, teratogenicity and ecotoxicity. This article evaluates the applicability of silver compounds as well as the classic antimicrobials triclosan, quaternary ammonium compounds, copper and further new options like chitosan and zeolite. It has to be emphasized that there are no objections against the use of antimicrobially active textiles if their use is equal or superior to other preventive or therapeutic measures. This applies to the amelioration of the course of dermatological diseases with disturbed skin flora, in particular atopic dermatitis, the prevention and therapy of acute and chronic wound infections by wound dressings, the use of impregnated surgical suture material as well as special indications in the prevention of infection in medical facilities. The use of antimicrobial textiles for the prevention of dermatomycosis by antifungal impregnation is of questionable use; the antimicrobial impregnation of textiles for deodorization purposes has to be avoided. Presently, from a hygienic point of view, the following questions have to be clearly determined: declaration of any antimicrobial impregnation; development of international standards for in vitro testing and preclinical evaluation of efficacy and tolerance; evaluation of the advantage of the antimicrobial properties for the intended use including the risk-benefit assessment.

Anti-Infective Agents↗
PubMed2002

Polysulfonates derived from metal thiolate complexes as inhibitors of HIV-1 and various other enveloped viruses in vitro.

Sodium 2-mercaptoethanesulfonate reacts with the metal ions Pd(II), Pt(II), Ag(I), Cd(II) and Zn(II) to yield complexes containing multiple anionic sulfonate sites. On the basis of spectroscopic and other analytical data the complexes were assigned the tentative molecular formulas: Pd6(SCH2CH2SO3Na)12, Ptn(SCH2CH2SO3Na)2n+2, Agn(SCH2CH2SO3Na)n, Na2Zn4(SCH2CH2SO3Na)10, and Na2Cd4(SCH2CH2SO3Na)10. The complexes displayed a variety of differences in activity towards DNA and RNA viruses. The platinum complex showed no measurable cytotoxicity and exhibited a spectrum of antiviral activity resembling that of dextran sulfate. It was active against HIV-1 and HIV-2, herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), thymidine kinase-deficient HSV-1, human cytomegalovirus, vesicular stomatitis virus (VSV), influenza A virus, respiratory syncytial virus (RSV), Sindbis virus, Junin virus and Tacaribe virus. The palladium complex also showed no measurable cytotoxicity, but was completely inactive against most viruses, with one notable exception: both HIV-1 and HIV-2 were substantially inhibited by the palladium complex. The silver complex showed significantly less antiviral activity and greater cytotoxicity than the platinum complex but did show some selectivity against RSV. The zinc complex showed only modest activity against VSV, RSV, Junin virus, and Tacaribe virus, and like the silver compound was more cytotoxic than either the platinum or palladium complex. The cadmium complex was toxic to all of the cell lines used for in vitro evaluation of antiviral activity. Based on these results, the platinum and palladium compounds appear to be promising candidates for further studies, that is, as vaginal microbicides in the prevention of genital HIV and/or HSV transmission.

Anti-HIV Agents↗
PubMed2006

Electric-current-assisted application of self-etch adhesives to dentin.

The use of electric current during the application of etch-and-rinse adhesive systems has been recently claimed to increase bonding of etch-and-rinse adhesives by enhancing substrate impregnation. The null hypothesis tested in this study was that electrically assisted application has no effect on bond strength of self-etching bonding systems. Three self-etch adhesives (Protect-Bond, Xeno III, and Prompt L-Pop) were applied with the aid of an electric signal-generating device (ElectroBond) and tested vs. controls prepared with the same disposable sponges but without electric current. Specimens bonded under the influence of electric current exhibited increased microtensile bond strength compared with the controls (p<0.05). High-resolution SEM analysis showed that bonding under the influence of electricity reduced interfacial nanoleakage. It is speculated that resin infiltration may be improved by the attraction of polar monomers by an electric current or by modification of the dentin surface charges, resulting in better water substitution or evaporation.

Ammonia↗