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At least 937 records · Page 52Linked to original sources
PubMed2006

A discussion of silver as an antimicrobial agent: alleviating the confusion.

Within the last 3 to 5 years, many silver-based antimicrobial dressings have become available and more are on the way. However, sometimes dressing manufacturers and authors make claims and send messages that conflict with data and conclusions in the literature, creating confusion for clinicians. A literature review of six relevant and frequently discussed topics was conducted. Pre-clinical and clinical study data suggest that: a) bacterial resistance to silver may occur, b) silver dissociation is affected by the test medium used, c) bactericidal activity differences may be a function of the bacterial strain used for testing, d) higher rather than lower levels of silver may be needed because Ag+ binds to proteins and nucleic acids, e) rapid delivery of silver (ie, rate of kill) may be a positive factor when considering prevention of silver resistance and biofilm formation, and f) based on the vast majority of in vivo studies available, silver does not adversely effect viable cells; thus, is not cytototoxic. Continued research into the implications of the data is warranted.

Anti-Infective Agents, Local↗
PubMed1990

Electron microscopical localization of the lead in peripheral blood neutrophils of the rat with timm sulphide silver method and X-ray probe microanalysis.

The distribution of lead ions in rat peripheral neutrophils was investigated using Timm sulphide silver method. In the neutrophils of adult male rats the Pb-precipitates were electron microscopically localized at 1.5, 3.0 and 6.0 hours after a single intraperitoneal injection of lead at dose 150 mgPb kg b. w. After increased lead ions input to cell matrix a formation of cytoplasmic metal deposits as well as an aggregation of Pb-complexes within deep invaginations of nuclear membrane was detectable. Furthermore, the neutrophils were prepared to examination by scanning electron microscope according to Domagała et al. (1979). In neither case there was a clear difference of neutrophil surface morphology between exposed and control populations. The same preparations were then used to X-ray probe microanalysis, and correlation between the presence of Timm reaction product and lead indication was obtained.

Animals↗
PubMed2006

[Biocompatibility test of polymethylmethacrylate denture base resin containing silver-supported antimicrobial agent STR-1 at nanometer level].

OBJECTIVE: To evaluate the biocompatibility of polymethylmethacrylate(PMMA) denture base resin containing silver-supported antimicrobial agent STR-1 of nanometer level in vitro. METHODS: According to the national standards for biological evaluation of dental materials, the cytotoxicity of denture base resin containing STR-1 at concentrations of 5 g/L and 10 g/L was examined by molecular filtrating method, and the hemolysis of STR-1, denture base resin containing STR-1 at concentrations of 5 g/L and 10 g/L was also surveyed. RESULTS: The control denture base resin without containing STR-1 and the denture base resins containing STR-1 at concentrations of 5 g/L and 10 g/L were not cytotoxic to L929 cells. Two hours and 24 hours after cell culturing, the filter membranes of the control and experimental groups were stained evenly with blue color. The staining intensity was not decreased and the fading areas were 0 mm2 during the culturing. The cytotoxicity grades were 0. The hemolysis rates of the antimicrobial agent STR-1 and the denture base resins containing STR-1 at concentrations of 5 g/L and 10 g/L were 1.7%, 3.5% and 3.7% respectively. They were less than the national guild standard 5% which represent no hemolysis. CONCLUSION: The PMMA denture base resins containing silver-supported antimicrobial agents STR-1 of nanometer level at concentrations of 5 g/L and 10 g/L exhibit good biocompatibility.

Animals↗
PubMed1991

Delayed neurotoxic effects of bis (1-methylethyl) phosphorofluoridate (DFP) in the European ferret: a possible mammalian model for organophosphorus-induced delayed neurotoxicity.

This study examined the effects of the organophosphorus delayed neurotoxicant bis (1-methylethyl) phosphorofluoridate (DFP) on the central nervous system of the European ferret. Animals received subcutaneous injections of either 2 or 4 mg DFP/kg b.w. The extent of neuropathology was determined by the Fink-Heimer method, the activities of neuropathy target esterase (NTE) and cholinesterase (ChE) by enzyme assay methods, and the severity of clinical signs by a graded scale. In ferrets injected with 4 mg DFP/kg b.w., dense axonal and terminal degeneration were noted at 21 and 28 days post-DFP in the gracile, inferior vestibular, and lateral reticular nuclei, medial and dorsal accessory nuclei of the inferior olive, and in cerebellar folia I-IV. Degeneration was also noted in laminae VI-VII throughout most of the spinal cord and in the ventral motor nucleus at the level of the cervical enlargement. Both NTE and ChE activities were maximally inhibited at 6 hr post-dosing. NTE activity returned to control levels by 4 days while ChE activities reached control levels at 21 days. Clinical signs at 21 and 28 days post-DFP ranged from slight hindlimb weakness to severe ataxia or hindlimb paralysis. Less severe degeneration and clinical signs were noted in the animals exposed to 2 mg DFP/kg b.w. These findings indicate that the European ferret may be a model species for assessing the effects of organophosphorus delayed neurotoxicants.

Animals↗
PubMed1990

Changes in distribution of chloride ions in embryonic chicken retinal pigment epithelium.

Changes in the distribution pattern of chloride ions were studied in the embryonic chicken retinal pigment epithelium (RPE), chloride ions being deposited as silver chloride (AgCl) in the RPE and observed by electron microscope. Before the 7th day after fertilization, the chloride ions did not accumulate anywhere in the tissue. From the 8th day, the chloride ions accumulated in the cytoplasm and the intercellular space, first in the posterior fundus RPE and later in the anterior fundus RPE. Melanin pigment granules and apical microvilli of the RPE developed from the posterior fundus toward the anterior fundus in parallel with the changes in the distribution pattern of chloride ions. These results suggest that the chloride ion transport function of the RPE appears first in the posterior fundus on the 8th day after fertilization and thereafter the development of the chloride ion transport moves to the anterior fundus. This development of the transport function appears to progress in parallel with the morphological development of the RPE cells.

Animals↗
PubMed1989

[Are Ag-points, gutta percha and amalgam still applicable for apical sealing?].

Nowadays Ag-points, gutta percha and amalgam are widely used as orthograde or retrograde root-filling materials. The biocompatibility of these materials however remains debatable. Ag-points are easy to manipulate and when used together with an appropriate cement, offer an adequate seal. Yet an important disadvantage is the susceptibility to corrosion resulting in argyrosis and inflammatory reaction. Tissue cultures proved these corrosion by products to be highly cytotoxic. Other investigations, reported that the inflammatory tissue response seen with gutta percha, may be due to small amounts of additives included in gutta percha. Equally, there is no unanimity concerning the biocompatibility of amalgam, and the extent of corrosion and inflammatory reaction is possibly related to the composition of the amalgam used. Nevertheless in vivo studies demonstrated that, when freshly mixed amalgam, gutta percha or Ag-points are implanted in the femur of rats, mature bone was formed in direct contact with these materials.

Animals↗
PubMed1989

Histochemical observation of distribution of chloride ion around ciliary epithelium.

Chloride ions are shown to be actively transported by the ciliary epithelium. The distribution of these ions around the ciliary epithelium was studied by electron microscopy: chloride ions were deposited as silver chloride (AgCl) in the tissue. Albino rabbits, bullfrogs and chick embryos just before hatching were used. In all the animals examined, the concentration of chloride ions was lower in the nonpigmented and pigmented epithelial cells of the ciliary epithelium than in the extracellular space. The chloride ions appeared to accumulate between the nonpigmented epithelial cells.

Animals↗
PubMedDate not supplied

Simple and rapid spectrophotometric method for determination of adrenaline and isoprenaline.

A simple, rapid, and specific method for determination of adrenaline bitartrate and isoprenaline sulfate was developed. The method is based on the oxidation reaction in aqueous solution of either adrenaline bitartrate or isoprenaline sulfate in the presence of silver oxide to give a red aminochrome measurable at 490 nm. The color is stable for 2 h. Beer's law is valid within a concentration range of 5-80 micrograms/mL for each drug. All variables were studied to optimize the reaction conditions. The method is specific for catecholamine drugs having a secondary amine in the side chain. Other catecholamines such as orciprenaline and noradrenaline do not interfere, and no interference was observed in the presence of common pharmaceutical adjuvants. Interference due to sodium metabisulfite and sodium chloride was circumvented. The validity of the method was tested by analyzing adrenaline injections and isoprenaline tablets. Good recoveries were obtained for these preparations. The results were comparable to those obtained by official procedures. The proposed method is also recommended as a stability indicating assay for oxidative degradation of both drugs.

Chemical Phenomena↗