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At least 703 records · Page 39Linked to original sources
PubMed2002

Broad-spectrum bactericidal activity of Ag(2)O-doped bioactive glass.

Bioactive glass has found extensive application as an orthopedic and dental graft material and most recently also as a tissue engineering scaffold. Here we report an initial investigation of the in vitro antibacterial properties of AgBG, a novel bioactive glass composition doped with Ag(2)O. The bacteriostatic and bactericidal properties of this new material and of two other bioactive glass compositions, 45S5 Bioglass and BG, have been studied by using Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus as test microorganisms. Concentrations of AgBG in the range of 0.05 to 0.20 mg of AgBG per ml of culture medium were found to inhibit the growth of these bacteria. Not only was AgBG bacteriostatic, but it also elicited a rapid bactericidal action. A complete bactericidal effect was elicited within the first hours of incubation at AgBG concentrations of 10 mg ml(-1). 45S5 Bioglass and BG had no effect on bacterial growth or viability. The antibacterial action of AgBG is attributed exclusively to the leaching of Ag(+) ions from the glass matrix. Analytical measurements rule out any contribution to AgBG-mediated bacterial killing by changes in pH or ionic strength or the dissolution of other ionic species from the biomaterials. Our observations of the dissolution profiles of Ag(+) from AgBG in the presence and absence of bacteria are consistent with silver accumulation by the bacteria.

Bacteria↗
PubMed1996

Mammographic halo sign revisited.

PURPOSE: To determine whether increased silver halide deposition accounts for some curvilinear areas of hyperlucency (halo signs) that surround breast masses on screen-film mammograms. MATERIALS AND METHODS: Breast images obtained in 43 women (aged 30-67 years; mean, 48.6 years) that showed a halo sign were selected from the authors' teaching files. Optical magnification (x8.0-12.5) of the masses with halos was used to establish the pattern of silver halide deposition in the film emulsion. RESULTS: True radiolucent halos, differentiated from Mach bands by means of the increased silver halide deposition in the film emulsion, were identified in 44 masses in 36 women. Partial true radiolucent halos were identified in 32 (73%) of 44 masses. Thirty-eight (86%) of the 44 masses were cysts; three (7%), fibroadenomas; two (4%), infiltrating ductal carcinomas; and one (2%), axillary lymph node metastasis. True radiolucent halos were more common in growing benign and malignant lesions. CONCLUSION: A halo is not always a perceptual illusion.

Breast Diseases↗
PubMed1987

Modifications of electrode design for recording monophasic action potentials in animals and humans.

An Ag-AgCl electrode for recording monophasic action potentials by pressure contact is described. The electrode is mounted in a hand-held support designed for epicardial recordings during open-heart surgery from both the anterior and lateral walls of the left ventricle with minimal displacement of the heart. The support allows the electrode to be manipulated without the need for direct vision by the surgeon to any desired position while ensuring perpendicular apposition of the electrode without risk of damage to the myocardium. The permanently mounted electrode is also suitable for animal experiments. The electrode may be used for endocardial recordings in animals by direct puncture. Either a straight or curved electrode may be chosen as dictated by the recording site. The monophasic action potentials recorded by this electrode are of a high quality in terms of configuration, lack of drift, and amplitude.

Action Potentials↗
PubMed1988

A new fabrication technique for directly coupled transmural cardiac electrodes.

Many current attempts at electrophysiological elucidation of cardiac arrhythmia mechanisms have centered around activation sequence mapping. This is most commonly performed with polarized unipolar or bipolar metal electrodes, which, because of unstable direct current (DC) base-line potentials, necessitate alternating current (AC)-coupled amplification. An ideal nonpolarizable unipolar electrode offers unhindered exchange of charge allowing for stable DC recordings of biological electrical activity. In addition to activation information, DC unipolar recordings enable quantitation of systolic and diastolic potentials, other low-frequency phenomena of interest such as repolarization, as well as rapid recovery from such rapid extreme potential shifts such as defibrillation. Previous attempts to apply nonpolarizable electrodes to transmural cardiac investigations required complex wick electrode techniques to prevent mechanical movement of the fluid-metal interface when chlorided silver wire was used. We have developed a technique to fabricate miniature sintered Ag-AgCl electrodes that are mounted at various locations on a 20-gauge stainless steel needle permitting stable transmural DC unipolar electrogram recordings in vivo. The electrodes are low noise, rugged, sterilizable, and reusable and should prove useful in three-dimensional electrophysiological characterization of the heart.

Animals↗
PubMed2006

Skin physiology and textiles - consideration of basic interactions.

The skin exerts a number of essential protective functions ensuring homeostasis of the whole body. In the present review barrier function of the skin, thermoregulation, antimicrobial defence and the skin-associated immune system are discussed. Barrier function is provided by the dynamic stratum corneum structure composed of lipids and corneocytes. The stratum corneum is a conditio sine qua non for terrestrial life. Impairment of barrier function can be due to injury and inflammatory skin diseases. Textiles, in particular clothing, interact with skin functions in a dynamic pattern. Mechanical properties like roughness of fabric surface are responsible for non-specific skin reactions like wool intolerance or keratosis follicularis. Thermoregulation, which is mediated by local blood flow and evaporation of sweat, is an important subject for textile-skin interactions. There are age-, gender- and activity-related differences in thermoregulation of skin that should be considered for the development of specifically designed fabrics. The skin is an important immune organ with non-specific and specific activities. Antimicrobial textiles may interfere with non-specific defence mechanisms like antimicrobial peptides of skin or the resident microflora. The use of antibacterial compounds like silver, copper or triclosan is a matter of debate despite their use for a very long period. Macromolecules with antimicrobial activity like chitosan that can be incorporated into textiles or inert material like carbon fibres or activated charcoal seem to be promising agents. Interaction of textiles with the specific immune system of skin is a rare event but may lead to allergic contact dermatitis. Electronic textiles and other smart textiles offer new areas of usage in health care and risk management but bear their own risks for allergies.

Anti-Infective Agents↗
PubMed1990

Absence of right-left asymmetries in the rat hippocampus as demonstrated by Timm staining.

Although biochemical and behavioural studies have shown right-left differences in several areas of the rat limbic system, some anatomical studies reported no significant right-left differences in several morphological parameters of the hippocampus. The purpose of the present study was to determine whether there are asymmetries in the micro-anatomy of the rat hippocampus by examining the intensity of Timm staining in various hippocampal fields and the area occupied by mossy fibres by the use of combined microdensitometric and quantitative image analysis techniques. Timm staining demonstrates the distribution of intrahippocampal association pathways because it is a histochemical marker of zinc and other heavy transition metals. There were no right-left differences in the density of Timm staining at the level of the dentate gyrus, in the dendritic layer of CA1 and CA2 fields, in the mossy fibre area or in the subiculum. These findings provide further evidence of a lack of morphological asymmetry in the rat hippocampus.

Animals↗
PubMed1983

Toxic effects of silver-silver chloride electrodes on vascular smooth muscle.

We found that silver, either as silver metal or silver chloride, exerted toxic effects on the smooth muscle of isolated cannulated hamster cheek pouch arterioles. Silver initially stimulated the smooth muscle, producing a marked vasoconstriction. The vessels then dilated back to control diameters. Once the arterioles began to dilate, they became refractory to norepinephrine or potassium stimulation. We caution the use of silver in the presence of smooth muscle, especially when tissue mass is small or free protein concentration is low.

Animals↗
PubMed2005

Effect of Sn doping on the growth and optical properties of AgI nanoparticles.

Controlled iodization and Sn doping of vacuum-evaporated Ag films has helped understand the initial-stage kinetics of AgI nanoparticle growth under ambient conditions. Use of XRD, optical spectroscopy, and AFM has unravelled systematic correlation between Sn-induced disorder in Ag crystal structure, nanoparticle size, and exciton growth dynamics. Sn doping of Ag leads to three specific effects: removal of UV absorption minimum in Ag, introduction of a plasmon-type absorption in the red region, and a reduction in particle size in thicker (than 10 nm) films (but an increase in particle size in 10 nm films) relative to that in undoped Ag films.

Crystallization↗
PubMed2006

Syntheses of Ag, PbSe, and PbTe nanocrystals and their binary self-assembly exploration at low size-ratio.

Nanocrystals of Ag, PbSe, and PbTe were prepared via a high-temperature organic solution approach, respectively. Using a size-selection technique, the size-distribution of each set of nanocrystals could be fine-tuned and finally monodisperse products were achieved. Superlattice structure of binary self-assemblies in low size-ratio were also explored and characterized by transmission electron microscopy. It is realized that a success of achieving binary self-assembly pattern is greatly dependent on several key factors including particle size-distributions, relative concentrations of both components, as well as the size-ratios between Ag and PbSe (or PbTe) nanocrystals.

Lead↗
PubMed1994

Interference by Parvolex with chloride estimation by the Ag/AgCl method.

We demonstrate significant interference by Parvolex (acetylcysteine) with the Ag/AgCl method for chloride estimation. A study of four patients who had taken a paracetamol overdose and been treated with Parvolex implied this interference, and an in vitro study confirmed it. The interference was shown to decline upon storage of the serum at a similar rate in both the patient and in vitro studies. Suggested mechanism for these phenomena are given.

Blood Glucose↗
PubMed1999

Stoichiometry of the leaching process of fluoride-containing aluminosilicate glass-ionomer glasses.

Dental glass-ionomer cements (GIC) set by an acid-base reaction between a polyalkenoic acid and an ion-leachable glass. The exact relationship between the glass composition and the setting and final properties of GIC is not yet fully elucidated. As part of a systematic study of this relationship, we studied the leaching stoichiometry of glasses used in commercial formulations to correlate the glass composition with its leaching properties. The leaching experiments were performed in acetic acid solutions at pH = 3.4 by means of a pH-stat method. After predetermined time intervals, the suspension was filtered and the filtrate was analyzed for the glass constituents. The usefulness of the pH-stat method for the determination of glass reactivity was corroborated. The deviation of the leaching stoichiometry with respect to the pure glass stoichiometry decreased with increasing relative content of mono- and bivalent glass network dwellers and modifiers. Indications were found that the latter can be leached out independently and preferentially, while the leaching of network dwellers is coupled with the aluminum release. The F content as well as the reactivity of the glass affect the amount of fluoride available for release from a set GIC. It could be concluded that the leaching stoichiometry of GIC glasses can be correlated with their absolute and relative composition.

Acetates↗