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Results for “Silver Compounds”

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At least 1,657 records · Page 92Linked to original sources
PubMed2005

A new self-assembling capsule via metal coordination.

A new octadentate cavitand forms a stable dimeric molecular capsule via metal-coordination, creating a large and elaborate three-dimensional cavity in which large aromatic guests are accommodated to form supramolecular complexes.

Dimerization↗
PubMed1994

Effect of low molecular weight heparan sulphate on angiogenesis in the rat cornea after chemical cauterization.

Vascularization of the cornea occurs in many pathological conditions and can result in loss of visual acuity. It is also thought that vascularization predisposes the cornea to reject grafts by facilitating the detection of foreign antigens in donor material. A rat corneal assay for angiogenesis was adopted in the present study to evaluate the possible angiostatic activity of a low molecular weight heparan sulphate (LMW-HS). Corneal lesions were induced by chemical cauterization at 2 mm from the corneoscleral limbus. Rats were randomized to receive two drops/eye four times daily, for 6 days, of a solution of LMW-HS in vehicle (2.5% carboxymethylcellulose), heparin, heparin plus hydrocortisone, or vehicle alone. After a 6 day-treatment period, the eyes were perfused with india ink and the degree of neovascularization was evaluated. In rats treated with vehicle alone a dense vascular network extending from the corneoscleral limbus to the cauterized site was observed; on the contrary, a markedly reduced vascular network was evidenced in animals treated with LMW-HS. The distribution of basic fibroblast growth factor (bFGF) in the cauterized cornea was also evaluated by using an immunohistochemical method. A marked bFGF immunoreactivity was demonstrated in corneal epithelium and stroma of control rats 12-48 hours after the cautery. These results lead to the assumption that LMW-HS could be used in ophthalmology to inhibit corneal neovascularization.

Animals↗
PubMed2004

Polymeric (mu2-nitrato-kappa2O:O')(mu2-nitrato-kappa2O:O)(mu4-pyridinium-4-thiolato-kappa4S:S:S:S)disilver(I).

The title compound, [Ag(2)(NO(3))(2)(C(5)H(5)NS)](n), was obtained from the reaction of silver nitrate with bis(4-pyridyl) disufide (4-PDS) in a mixture of ethanol and water, which suggests that the disulfide bond of 4-PDS can be cleaved under mild conditions. The structure of the title compound is a two-dimensional infinite array in which the asymmetric unit contains two Ag atoms, a pyridinium-4-thiolate molecule and two nitrate groups. Each pyridinium-4-thiolate molecule acts as a mu(4) bridge, linking four Ag atoms, with Ag-S bond distances of 2.4870 (19), 2.5791 (19), 2.5992 (19) and 2.848 (2) A. The Ag.Ag distances lie in the range 2.889 (2)-3.049 (1) A.

Journal Article↗
PubMed1994

Human interindividual variability--a major source of uncertainty in assessing risks for noncancer health effects.

For noncancer effects, the degree of human interindividual variability plays a central role in determining the risk that can be expected at low exposures. This discussion reviews available data on observations of interindividual variability in (a) breathing rates, based on observations in British coal miners; (b) systemic pharmacokinetic parameters, based on studies of a number of drugs; (c) susceptibility to neurological effects from fetal exposure to methyl mercury, based on observations of the incidence of effects in relation to hair mercury levels; and (d) chronic lung function changes in relation to long-term exposure to cigarette smoke. The quantitative ranges of predictions that follow from uncertainties in estimates of interindividual variability in susceptibility are illustrated.

Disease Susceptibility↗
PubMed1974

Cell-free mercury(II)-reducing activity in a plasmid-bearing strain of Escherichia coli.

The ability to reduce Hg(II) to Hg(0), which is determined by a plasmid-borne gene in Escherichia coli, is conferred by a Hg(II)-inducible activity which is located in the cytoplasm rather than in the periplasmic space of the cell. This Hg(II)-reducing activity can be isolated from the supernatant of a 160,000 x g centrifugation after French Press disruption of the cells. The activity is dependent on glucose-6-phosphate, glucose-6-phosphate dehydrogenase, and 2-mercaptoethanol, but is not enhanced by added nicotinamide adenine dinucleotide phosphate. Treatment of the active fraction with N-ethylmaleimide causes irreversible loss of the Hg(II)-reducing activity. Unlike the Hg(II)-reducing activity found in intact cells, the cell-free activity is not inhibited by toluene, potassium cyanide, or m-chlorocarbonylcyanide-phenylhydrazone; however, it is inhibited by Ag(I) and phenylmercuric acetate to the same extent as the activity in intact cells. Neither phenylmercuric acetate nor methylmercuric chloride is reduced to Hg(0) by the cell-free activity. Au(III), however, is a substrate for the cell-free activity; it is reduced to metallic colloidal Au(0).

Alkaline Phosphatase↗
PubMed2001

Efficacy of antiadhesive, antibiotic and antiseptic coatings in preventing catheter-related infections: review.

In recent years, central venous catheters (CVCs) are increasingly used in clinical practice. However, complications such as local or systemic infections are frequent for both temporary and indwelling vascular catheters. Annually, in the United States of America there are more than 200,000 cases of nosocomial bloodstream infections (BSIs), of which 90% are related to the use of an intravascular device. These infections are associated with increased morbidity and mortality, prolonged hospitalization and growing medical costs. Technological treatments of polymer surfaces including coating the catheter with antimicrobial substances may be promising tools for prevention of catheter-associated infections. A large number of surface-treated central venous catheters are now commercially available. In this paper the features and the clinical efficacy of different antimicrobial coatings are reviewed.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Treatment of venous stasis ulcers with Unna's boot and activated charcoal].

In this study the author describes the results of venous stasis ulcers treatment using Unna's boot and activated coal and silver in 47 patients aged 30-80. Total treatment time was from 2 to 16 weeks, with the average of 6 days between two consecutive bandages. Among these 47 patients, 87% have had their wounds healed, 8.5% have been unsuccessful in healing them and 4.5% have dropped the treatment, the main profits observed were the decrease of bandage number, patients and Public Health Service money saving and treatment compliance.

Adult↗
PubMed1988

Silver staining of the nucleolar organizer regions (NORs) in semithin Lowicryl sections.

The one-step silver technique was applied to semithin Lowicryl sections of root meristem cells of Allium cepa and a human tumor cell line (TG cells). In vegetal cells, after 5 min of staining reaction, the Ag-NOR proteins formed ring-shaped structures peripherally within the nucleolus. In animal cells silver granules were distributed over the entire nucleolus. The specificity of the staining reaction was increased by incubation of the sections in NH4Cl and Schiff's reagent prior to Ag-NOR silver staining.

Allium↗
PubMedDate not supplied

The effect of tooth preparation on microleakage behavior.

Many factors contribute to the microleakage of a restoration. One of the more important is the method of cavity preparation. This study compared the microleakage behavior of composite restorations placed in cavities prepared by different techniques. It also compared and correlated the microleakage data produced by an electrochemical vs a staining technique. Class V cavities were prepared in 48 premolars by four techniques: (1) tungsten carbide bur in a high-speed handpiece followed by acid etching; (2) air abrasion (27 microns Al2O3) followed by acid etching; (3) air abrasion (50 microns Al2O3) and (4) air abrasion (27 microns Al2O3), with n = 12 in each group. All teeth were restored with Prime and Bond 2.1 and Tetric Flow, then thermocycled between 5 degrees and 55 degrees C for 5000 cycles with a one minute dwell at each temperature. After thermocycling, a PVC-covered Cu wire was inserted apically into the pulp chamber of each tooth and sealed into position. Leakage was continuously followed by a conductimetric method for 75 days. The teeth then were immersed in 50% AgNO3 for two hours, rinsed in distilled water for 60 seconds, then placed in a rapid photographic developer solution for two hours, followed by rinsing and sectioning for microscopic examination. Electrochemical data were examined by ANOVA and Newman-Keuls multiple comparison tests, while Kruskal-Wallis and Rank Sum Difference tests were used on the staining evaluations. Spearman's rho test was used to correlate the two test techniques. Electrochemical data for cavities prepared with a bur or air abrasion followed by acid etching prior to restoration showed significantly less (p < or = 0.05) microleakage (mean leakage currents of 1.89 & 1.57 microA, respectively) than teeth prepared with air abrasion alone (mean leakage currents of 3.60 & 3.40 microA, respectively). Rank sum AgNO3 staining data (196 & 242 vs 371 & 368) supported these findings. The correlation between the electrochemical and staining data was significant (p < or = 0.05) for all four groups of test specimens.

Acid Etching, Dental↗
PubMed1977

[pH-dependence characteristics of Ca-ATPase activity of heavy meromyosin with modified SH-groups].

Study of pH-dependence of Ca-ATPase activity of heavy meromyosin (HMM) at low and high ionic strength showed essential differences in the modifying effect of two sulfhydryl reagents, p-CMB and silver. Silver ions in conditions studied independently on pH and KCl concentration produce an inhibition of ATP hydrolysis by myosin and HMM, the shape of the pH-dependence curve remaining similar to that of the native enzyme up to 40% of blocking free sulfhydryl groups. At the same degree of binding of sulfhydryl groups with p-CMB at 0,5 M KCl the pH-dependence curve due to activation at neutral pH changes it's shape and becomes similar to that for dissociation of two ionizable groups (at neutral and alkaline regions). In contrast to this, a low or zero concentrations of KCl no activation was observed for the enzyme with 40-50% of SH-Groups modified by p-CMB and Ca-ATPase in this case seemed to be independent of pH. The data obtained suggest that SH-Groups are not included into the active site of myosin, and the activating effect observed for some sulfhydryl reagents, is due to conformational changes and it can be the result of the penetrance of the organic part of the reagent molecule into hydrophobic region of the protein.

Adenosine Triphosphatases↗
PubMed1989

Effect of inhibitors of arachidonic acid metabolism on corneal neovascularization in the rat.

We used computerized image analysis to evaluate quantitatively the ability of topically applied corticosteroids (dexamethasone sodium phosphate, prednisolone acetate), cyclooxygenase inhibitors (flurbiprofen, indomethacin, ketorolac), lipoxygenase inhibitors (REV 5901, esculetin, quercetin), and dual cyclooxygenase/lipoxygenase inhibitors (BW 755C, BW A540C) to reduce corneal neovascularization in the rat induced by silver/potassium nitrate cauterization. Significant decreases in the neovascular response were found with corticosteroids and cyclooxygenase inhibitors. A complete dose-response curve was performed for a representative compound from each class. Dexamethasone was found to be superior to flurbiprofen in its ability to reduce neovascularization in this model, while no significant inhibition was noted with either REV 5901 or BW 755C, even at high doses. We conclude that the corneal angiogenic response in this model can be reduced by inhibition of cyclooxygenase as well as by other mechanisms that are steroid-dependent but are, as yet, poorly defined.

Administration, Topical↗