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At least 73 records · Page 4Linked to original sources
PubMed2000

[Basic study on anti-bacterial urethral catheter. I. Development of a new anti-bacterial coating material for silicon catheters].

In order to develop a new anti-bacterial urethral catheter, we studied anti-bacterial and anti-adherent coating material suitable for silicon catheters. Several aspects of various silver compounds were examined, including anti-bacterial activity, chemical property and toxicity. Among silver citrate, silver phosphate and silver oxide, which were found to have excellent anti-bacterial activities, silver citrate was regarded as the material of choice for anti-bacterial coating in terms of durable activity and biological safety. It was also found that several surfactants inhibited bacterial adherence to the surface of silicon catheters. Among them soybean lecithin exhibited excellent anti-adherent activity in a dose dependent manner. Finally, a mixture of silver citrate, soybean lecithin and liquid silicon at the ratio of 2:2:8 was regarded as an ideal anti-bacterial coating material for silicon catheters.

Animals↗
PubMed2000

Digestion method for silver accumulated in micro-organisms.

Silver is accumulated to high concentrations in certain microbial strains. Here a bomb digestion method is proposed, using HNO3 and HCl, for the extraction and digestion of silver and silver compounds from the organic matrix. The method is applicable for the quantitative determination of silver by inductively coupled plasma atomic emission spectroscopy.

Bacteria↗
PubMed2001

Diversity of silver resistance genes in IncH incompatibility group plasmids.

Silver compounds are used as antimicrobial agents in medicine and bacteria that develop resistance to silver cations (Ag(+)) pose problems similar to those of antibiotic-resistant bacteria. The first set of Ag(+) resistance genes (sil) was from plasmid pMG101, now assigned to the IncHI incompatibility group. Questions of whether sil genes are unique to pMG101 or are more widely found, and whether they are associated with a specific incompatibility group or occur in many plasmid groups and on bacterial chromosomes were addressed. sil genes were identified in five IncH plasmids, but not in plasmids of the IncP incompatibility group. Three sil genes (silP, silR and silE) from these plasmids were PCR-amplified, cloned, sequenced and compared to those of pMG101. Differences of 0-50 nt per kb of sequence were found. Predicted gene products were 0-6% different in amino acid sequence, but the differences did not alter residues thought to be involved in protein function (see supplementary data at http://mic.sgmjournals.org or http://www.uic.edu/depts/mcmi/individual/gupta/index.htm). For representative IncH plasmid R476b and pMG101 the effects of Ag(+) exposure on resistance levels were measured by growth. The inducibility of silC, silR and silE gene expression after Ag(+) exposure was studied by reverse transcriptase (RT)-PCR. Silver resistance increased after Ag(+) exposure for strains carrying plasmid R476b. silC and silE expression from R476b was inducible after Ag(+) exposure and was constitutive and high from pMG101. The mRNA levels for the regulatory gene silR was constitutive for both pMG101 and R476b. Close homologues for silABC(ORF96)RS from pMG101 are clustered on the chromosomes of Escherichia coli strains K-12 and O157:H7, without contiguous silP and silE homologues. Insertion deletions of the E. coli K-12 chromosomal homologues for silA and silP gave Ag(+) hypersensitivity for growth. The silA homologue knockout was complemented back to wild-type resistance by the same gene cloned on a plasmid. Homologues of sil genes have also been identified on other enterobacterial genomes.

Anti-Bacterial Agents↗
PubMed1985

Tissue deposition of silver following topical use of silver sulphadiazine in extensive burns.

Silver sulphadiazine has been applied to the burn wounds of 509 patients during the past 10 years. Eleven patients with burns covering more than 20 per cent of the body surface showed silver deposits in the mucosa of the lips, gingiva and cheeks. The colour of the burn wound was also slightly darker than in patients not treated with silver compounds. This darker colour spontaneously disappeared during the year following discharge from hospital. The pathogenesis of silver deposition has been discussed in relation to other published studies.

Administration, Topical↗
PubMed1996

Extraction and separation of silver using triphenylphosphine sulphide.

Silver compounds are used in pharmaceutical and ayurvedic medicines. A method is proposed for the extraction separation of silver from Cu, Cd, Zn, Ni, Pt (IV) and Au (III) from nitrate solution using triphenylphosphine sulphide as an extractant. The recovery of silver is tested both volumetrically and/or by ICP-AES technique.

Journal Article↗
PubMed1980

Endogenous and exogenous ocular and systemic silver deposition.

The ocular distribution of particulate silver after prolonged ingestion and the topical application of an organic silver compound (argyrol) are described and compared with the distribution after long-term occupational contact with refined silver. The deposits appear to be inert and to cause no functional visual deficit.

Aged↗
PubMed1978

Silver impregnation methods for reticulum fibers and reticulin: a re-investigation of their origins and specificity.

Maresch (1905) introduced Bielschowsky's silver impregnation technic for neurofibrils as a stain for reticulum fibers, but emphasized the nonspecificity of such procedures. This lack of specificity has been confirmed repeatedly. Yet, since the 1920's the definition of "reticulin" and studies of its distribution were based solely on silver impregnation technics. The chemical mechanism and specificity of this group of stains is obscure. Application of Gomori's and Wilder's methods to human tissues showed variations of staining patterns with the fixatives and technics employed. Besides reticulum fibers, various other tissue structures, e.g. I bands of striated muscle, fibers in nervous tissues, and model substances, e.g. polysaccharides, egg white, gliadin, were also stained. Deposition of silver compounds on reticulum fibers was limited to an easily removable substance; the remaining collagen component did not bind silver. These histochemical studies indicate that silver impregnation technics for reticulum fibers have no chemical significance and cannot be considered as histochemical technics for "reticulin" or type III collagen.

Connective Tissue Cells↗
PubMed2005

[Antimicrobially effective compounded medications. Clinical value and critical comments].

Triphenyl-methan dyes, traditionally used in dermatology should be reevaluated with caution. Their use should be limited due to the uncertain pharmacological-toxicological risk-benefit ratio and the lack of pharmacological quality of the raw substances. Sometimes antimicrobial activity is insufficient and the cytotoxic effects, along with the inhibition of wound healing, make these dyes less suitable for topical treatment in dermatology. Chinolinolsulfat (Chinosol) and Clioquinol should be used in low concentrations and only on small areas. Due to their negative benefit-risk profile ethracidinlactate-monohydrate (Rivanol) and phenylmercuri-borate (Mercuchrom) should not be used as topical antimicrobial substances. The present publication is intended to give practical recommendations on compounded medications for topical antimicrobial use. Even though some of the cited compounds must be considered critically, we recommend the topical use of chlorhexidine salts, polihexanide, triclosan, polyvidone iodide and silver compounds. Useful standardised compounded formulations containing these four groups are listed in the NRF (Neues Rezeptur Formularium: New German Pharmacopoeia for compounded medication).

Anti-Bacterial Agents↗
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↗
PubMed2003

Stability of the gold(i)-phosphine bond. A comparison with other group 11 elements.

The stability of gold phosphine complexes of the form [Au(PH(3))(n)()](+) (n = 1-4) and [AuCl(PH(3))(n)()] (n = 1-3) is analyzed in detail by applying quantum theoretical methods and compared to the coordination behavior of the lighter group 11 elements copper and silver. It is shown that, once [M(PH(3))(2)](+) or [MClPH(3)] (M = Cu, Ag, and Au) is formed, further coordination by PH(3) ligands is relatively weak; i.e., the energy gain to form [M(PH(3))(3)](+) from [M(PH(3))(2)](+) is less than 60 kJ mol(-)(1), and less than 100 kJ mol(-)(1) to form [MCl(PH(3))(2)] from [MClPH(3)]. Relativistic effects in gold significantly influence these factors and reduce the tendency for phosphine coordination beyond two-coordination. This implies that the most favored coordination number for gold is two with either a linear P-Au-P or P-Au-X arrangement (X = a strongly coordinating ligand like Cl(-)). Instead, X-Au-PH(3) units prefer to interact via close Au-Au contacts (aurophilic interactions) keeping the linear structure approximately intact, while the corresponding copper and silver compounds prefer PH(3) coordination to strongly bound M(2)Cl(2) units (M = Cu or Ag) where two chlorine atoms bridge the two metal atoms thus having the formal coordination number of three for copper or silver.

Journal Article↗
PubMed1978

Structures of silver sulfonamides.

The structures of silver sulfonamides were found to depend highly on the substituent at the amide nitrogen of the sulfonamide. Silver is coordinated to that nitrogen and the sulfonamide is in the amido form if no substituent is present or if the substituent is a phenyl, acetyl, or 2-pyrimidyl group. If the substituent is a 2-thiazolyl or 2-pyridinyl group, the sulfonamide is in the imido form and silver coordinates to the nitrogen of the substituent. Depending on the number of suitable donor atoms per sulfonamide, the silver compounds are charged or uncharged and the primary amino group may be involved in complexation.

Chemical Phenomena↗
PubMed2000

Control of Pythium root rot on hydroponically grown cucumbers with silver-coated cloth.

Silver-coated cloth (SCC) effectively controlled root rot that was caused by Pythium aphanidermatum in hydroponically grown cucumber plants. The presence of SCC in the hydroponic solution reduced the root rot from 100% to 10% 20 days after inoculation with zoospores of P. aphanidermatum. It was suggested that the inhibition of SCC was caused not only by the silver ion dissolved from SCC, but also by the metallic silver and silver compounds formed on the surface of the root.

Cucumis sativus↗
PubMed1989

Absence of toxic effects in silver reclamation workers.

Recent reports have alleged that silver presents a toxic hazard to exposed workers. To define the potential risks of long-term exposure to silver better, a cross-sectional investigation was conducted of 27 Caucasian males occupationally exposed to primarily insoluble silver compounds and 27 matched referents. Physical examination and electron microscopy of skin biopsies revealed no cases of generalized argyria. Measurements of facial discoloration, judged from color photographs by panels of laymen and physicians, showed no significant difference between the two groups. Although 29% of the silver workers and none of the referents exhibited ocular silver deposition, optometric and contrast sensitivity test results revealed no significant deficits in visual performance. The kidney and respiratory findings were essentially normal in both populations. Despite the increased presence of silver in the blood, feces, and hair of the recovery workers versus the referents, there was no evidence that chronic silver exposure adversely affected the health of these employees.

Air Pollutants, Occupational↗
PubMed1996

The autometallographic zinc-sulphide method. A new approach involving in vivo creation of nanometer-sized zinc sulphide crystal lattices in zinc-enriched synaptic and secretory vesicles.

A new version of Timm's sulphide silver method involving in vivo binding of zinc ions in zinc enriched terminals is presented. By injecting sodium sulphide into the vena cava of deeply anaesthetized animals, it is possible to bind chemically the vesicular zinc, i.e. chelatable zinc (zinc ions), in secretory and synaptic vesicles, in the form of zinc sulphide crystal lattices. Four minutes after the intravenous injection the animal is perfused transcardially with a phosphate-buffered solution of glutaraldehyde, glutaraldehyde and formaldehyde, or with a saline solution. The nanometer-sized catalytic crystals can then be silver-amplified in cryostat and vibratome sections by exposure to an autometallographic developer. It is demonstrated that contemporaneously with silver enhancement, the zinc sulphide crystals are transformed to the corresponding silver sulphide crystals. For ultrastructural studies, autometallographic development of vibratome sections is recommended. From these sections tissue blocks are cut from the areas of interest, blockstained with osmium tetroxide and embedded in Epon. This approach results in a zinc-specific autometallographic staining of the sections of a hitherto unseen, high technical quality.

Animals↗
PubMed2004

Evaluation of the protective effects of reactive sulfide on the acute toxicity of silver to rainbow trout (Oncorhynchus mykiss).

Acute 96-h toxicity tests were performed with juvenile rainbow trout (Oncorhynchus mykiss) exposed to AgNO3 in either the absence or the presence of 100 nM reactive sulfide to evaluate the protective effect of aqueous sulfides against ionic Ag toxicity. The sulfide was presented in the form of zinc sulfide (ZnS) clusters under oxic conditions. Silver was lost from the water column during the course of the experiment, so mean measured Ag concentrations were used to generate all median lethal concentration (LC50) data. The system was complicated in that Ag2S precipitated because of the need for large amounts of Ag to obtain lethal effects in the presence of ZnS. Some of the losses of Ag could be explained by complexation with ZnS and formation of solid Ag2S. Other losses were probably the result of partial adsorption to exposure-chamber walls or to complexation with ligands or functional groups within organic material produced by the fish. The LC50 (95% confidence interval) values generated using measured concentrations for total Ag were 139 (122-162) nM in the absence of sulfide and 377 (340-455) nM in the presence of 100 nM sulfide. The LC50 values generated using measured concentrations from filtered (pore size, 0.45 microm) water samples were 122 (105-145) nM in the absence of sulfide and 225 (192-239) nM in the presence of 100 nM sulfide. These results suggest a stoichiometric protection of sulfides up to a 2:1 ratio of Ag:sulfide. Greater accumulation of Ag at the gills was measured in fish exposed to AgNO3 in the presence of sulfide.

Animals↗
PubMed2000

Phosphine sampling and analysis using silver nitrate impregnated filters.

In the field of industrial hygiene, besides the necessity of monitoring phosphine with direct reading apparatus to prevent accidents, there is a need for a method of sampling and analysing phosphine to control workers' exposure. The use of filters impregnated with silver nitrate to collect arsine, phosphine and stibine in workplace air has been described in the literature. Having previously chosen this type of filter to collect arsine, we studied its characteristics for phosphine capture. A filter impregnated with sodium carbonate was used both as a prefilter to collect the particles and to trap arsenic trioxide. After dissolving the silver compounds in nitric acid, ICP emission spectrometry was used to carry out the analysis. This article describes the comparative sampling we performed in a microelectronic laboratory and in a fumigation chamber (130 samples) to determine the concentration of AgNO3 impregnation solution to be used, the detection limit of the method and the retention capacity of the impregnated filters. Interference with other gases reacting with silver nitrate was studied and the storage time for sampled filters and analysis solutions was checked. The detection limit of the adopted method is better than 1 microg per filter, and the retention capacity exceeds 300 microg per filter. The problem of how to sample phosphine when H2S, NH3, or HCl is present has been solved, but the problem of sampling phosphine in atmospheres where acetylene evolves remains. Sampled filters and filter solutions are stable for more than three months at ambient temperature.

Environmental Monitoring↗
PubMed1981

Peptide segment coupling in aqueous medium: silver ion activation of the thiolcarboxyl group.

The use of the thiolcarboxyl function for the assemblage of deblocked peptide segments in aqueous medium has been investigated. The C-terminal thiolcarboxyl peptide Ac-Tyr-Arg-Arg-Glu-Arg-Gly-SH (2a) has been synthesized by the solid-phase method. The silver compound of peptide 2a was coupled to H-Phe-Ala-Glu-Gly-OH in 50% aqueous dimethylformamide to give a 40% yield of Ac-Tyr-Arg-Arg-Glu-Arg-Gly-Phe-Ala-Glu-Gly-OH.

Amino Acid Sequence↗