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PubMedDate not supplied

Kinetics of bacterial survival on polymer coatings with particular reference to indoor air quality.

The goal of the present study was to assess the bactericidal properties of various polyester coatings (PES) with and without anti-bacterial additives such as silver or polymer compounds. Under the experimental conditions used, the release of anti-bacterial additives was not an appreciable factor. The survival rate of Enterococcus faecalis mainly depended on environmental factors such as the relative humidity and the presence of nutrients. Based on the experimental points and the mathematics of disinfection, it was possible to model the survival kinetics of airborne bacteria after settling on polymer coatings. On clean materials, the coatings displayed an anti-bacterial property. Nevertheless, this was not sufficient, first, to ensure hygiene and indoor air quality and, secondly, to be adapted in domestic appliances or in hospitals. Indeed, most of the bacterial population still survived after several days' exposure. This weak effect of the anti-bacterial additives could be explained by their accessibility at the coating/bacteria interface.

Air Pollution, Indoor↗
PubMed1981

Inhibition by metals of a canine renal calcium, magnesium-activated adenosinetriphosphatase.

A number of metals were examined for inhibition of a canine renal calcium, magnesium-activated adenosinetriphosphatase (Ca2+, Mg2+-ATPase). Of the 27 metals investigated, only compounds of mercury, silver, gold, and uranium demonstrated 50% inhibition of the enzyme at concentrations lower than 10(-4) M. The order of inhibitory potency was Hg greater than Ag greater than U greater than Au. Organic mercury (chlormerodrin, mersalyl, p-chloromercuribenzoate) was less potent than inorganic mercuric chloride, but organic gold sodium thiomalate was equipotent with inorganic gold chloride. The inhibition produced by each metal decreased parallel to the decrease in enzyme activity, seen as the source of enzyme moved from the outer cortex inward to the papilla of the kidney. The regions of highest activity showed the greatest inhibition by each metal, and inhibition decreased as the control activity of the tissue decreased. This variability of inhibition was not related to the protein content of the enzyme preparation. As the ATP concentration increased, the inhibition produced by U was reduced; if the Mg (but not the Ca concentration) was increased while the ATP concentration remained constant, the inhibition increased. Changes in the Ca, Mg, and ATP concentrations did not alter the inhibition produced by Hg, Ag, and Au.

Animals↗
PubMed1990

Demonstration of a surface antigen of Clostridium tyrobutyricum by use of immunoblotting with a monoclonal antibody.

A monoclonal antibody, prepared against whole cells of Clostridium tyrobutyricum, recognized a surface antigen extracted by heat treatment or by hot phenol-water treatment. This antigen, after analysis by polyacrylamide gel electrophoresis and immunoblotting, has been shown to present a regularly-spaced ladder pattern similar to those shown by the lipopolysaccharide of many gram-negative bacteria. The proteinase K has been shown to have no effect on the recognition of this epitope by the monoclonal antibody. On the contrary, the inhibition of the antigen reactivity to the monoclonal antibody after a mild periodate oxidation suggests the involvement of a carbohydrate moiety in the epitope. Moreover, the SDS-PAGE analysis of phenol-water extracts has shown an additional compound, detected by silver staining but not recognized by the monoclonal antibody.

Antibodies, Monoclonal↗
PubMed1979

Resolution of saturated and unsaturated 5 beta-cholanoic acids by gas-liquid and thin-layer chromatography.

The thin-layer and gas-liquid chromatographic properties of the methyl ester acetates were determined for a series of 20 monounsaturated 5 beta-cholanoic acids representing the simple chemical and enzymic dehydration products of the common bile acids. The unsaturated acids were generally indistinguishable from their saturated analogues by thin-layer chromatography on plain silica gel, but resolution was achieved on silica gel impregnated with silver nitrate for compounds having sterically exposed double bonds. The gas-liquid chromatographic behaviour of the unsaturated bile acids on the OV-225, SE-30, and Poly-S-179 liquid phases was closely similar to that observed for the saturated bile acids. The 5 beta-cholenoic acids obeyed the general rules of chromatographic mobility based on the overall shape of the molecule and the number and configuration of functional groups, with a constant retention factor attributable to the olefinic bond. The structural information provided by the chromatographic behaviour of the standard unsaturated bile acids allows a distinction to be made among most of the isomeric 5 beta-cholenoates. A complete identification of all isomeric olefins is possible when chromatographic and mass spectrometric data are combined.

Bile Acids and Salts↗
PubMed1965

REACTION OF THE CARCINOGEN DIMETHYLNITROSAMINE WITH PROTEINS AND WITH THIOL COMPOUNDS IN THE INTACT ANIMAL.

1. [(14)C]Dimethylnitrosamine was administered to rats, and the formation of free and protein-bound S-methylcysteine was investigated. 2. Very little S-methylcysteine was found in liver acid-soluble fraction, in liver protein or in urine. 3. The methylhistidines formed in liver protein were found to have largely disappeared by 6 days after injection of dimethylnitrosamine. 4. The significance of these results in the carcinogenic action of dimethylnitrosamine is discussed.

Alkylation↗
PubMed2003

Improved synthesis of pure [18F]fluoro-compounds for PET studies from bromo-compounds.

For preparing [18F]labeled compounds free from bromo-compounds for PET (positron emission tomography) studies, we propose the following two processes in which no separation is needed between the fluoro-compound and bromo-compound : (1). the bromo-compound is first converted into O-tosylate, which is then [18F]fluorinated; and (2). after [18F]fluorination of the bromo-compound, its excess is converted into an easily separable compound, e.g., phthalimide-compound. Direct tosylation with silver tosylate was effected in 65-85% yield for most commercial bromo-compounds, and with potassium phthalimide, the bromo-compounds in cold run were converted easily into phthalimide-compounds in 84-90% yield.

Chemistry, Organic↗
PubMed2001

[A comparison of SERS of positive and negative nano-silver adsorbing cation and anion molecule].

A study on the negative charge colloid of nano-silver particles with anion and cation molecules has been done. The results of the experiment show that the negative charge colloid of nano-silver particle has no SERS effect when anion molecule adsorbed on its surface. While the cation molecule in adsorbed on its surface the SERS effect is enhanced. The SERS effects are just opposite when the two molecules separately adsorbed on the surface of the positive colloid of nano-silver particles. The paper hypothesizes that strong SERS effect can be got by using proper colloid of nano-silver particles. It is practical to develop the use of SERS.

Adsorption↗
PubMed2004

Photochemical deposition of SERS active silver nanoparticles on silica gel and their application as catalysts for the reduction of aromatic nitro compounds.

We report an impregnation technique for immobilization of silver(I) gelatin complex on silica gel. Subsequent UV exposure of the dry impregnated silica gel deposited silver nanoparticles on the solid matrix. Conventional techniques (UV-visible spectroscopy, TEM, EDAX, and thermal analysis) have been used to identify and characterize silver particles on silica surfaces. The photoproduced silver particles have shown unique SERS activity that authenticates the presence of silver nanoclusters in the silica matrix. Hence, the surface of the silica matrix remains SERS-active for months. This surface activity of the silica matrix inspired us to successfully study the catalytic reduction of nitro-compounds in aqueous, organic, and three different micellar media. Different thermodynamic parameters for the reduction processes have also been evaluated. Catalytic activity of the particles in micelles is explained in the light of hydrophobic and electrostatic interactions between the substrate and the micelles.

Journal Article↗
PubMed1997

Sensitive in situ hybridization with catalyzed reporter deposition, streptavidin-Nanogold, and silver acetate autometallography: detection of single-copy human papillomavirus.

The usefulness of standard in situ hybridization for viral nucleic acid detection is occasionally limited by its sensitivity limit of 10 to 50 copies per cell. A modified version of the recently described signal amplification method, catalyzed reporter deposition (CARD), and its application to formalin-fixed cells and tissue sections is presented. Deposition of the reporter is facilitated by using horseradish peroxidase catalyzing the deposition of biotinylated tyramide on the location of the probe target. The biotin accumulation created is usually detected with streptavidin-labeled enzymes or fluorochromes. In the present investigation, this step was replaced by streptavidin-Nanogold and combined with silver acetate autometallography. This resulted in deep-black precipitation at positive in situ hybridized reaction sites. The sensitivity of this new approach was tested with a biotinylated, genomic probe specific for human papillomavirus (HPV)-16/18. SiHa cells, a cervical carcinoma-derived cell line with one to two HPV16 copies per cell, and 10 histologically confirmed cervical carcinomas were used for the study. All samples were previously HPV16 positive with solution polymerase chain reaction, but only two of the cervical carcinomas were positive with standard in situ hybridization with barely visible signals. When employing CARD-Nanogold, SiHa cells and 9 of 10 biopsies proved positive with marked signals. It is concluded that this nonisotopic method can detect single viral copies in situ in routinely fixed material and may have the potential to replace in situ polymerase chain reaction in many applications.

Acetates↗
PubMed2000

[Syntheses, reactions and spectroscopic properties of cluster compounds containing ME4 (M = Mo, W; E = S, Se) units].

The synthetic reactions and spectroscopic studied of molybdenum (tungsten) -copper (silver, iron) -sulphur (selenium) cluster compounds, which can be prepared by the stepwise or unit construction reactions through the successive addition ML (L = Cl, Br, Sr, R2 etc) across six edges or four faces of ME4 (M = Mo, W; E = S, Se) tetrahedra, are described. A series of Mo (W)-Cu-S cluster compounds, (Et4N)2 [MCu2E4 (S2CNR2)2], (Et4N)2 [MCu2E3O (S2CNR2)2], [MCu2E4 (dppe)2] (dppe = bis (diphenylphosphine) ethane), (Et4N)2 [MCu3E4 (S2CNR2)4] (M = Mo, E = Se, R = Et (1a), R2 = C4H8 (1b), R = PhCH2 (lc)), (Et4N)2 [MCu4E4 (S2CNR2)4] (M = Mo, E = Se, R = Me (2)) (Et4N)2 [M2Cu4S8 (S2CNEt2)2], (Et4N)2 [M2Cu4S6O2- (S2CNC4H8)2], [Mo2Cu4S8 (dppm)2], [Mo2Cu4S6O2 (dppm)2], (dppm = bis (diphenylphosphine) -methane), (Et4N)4 (ME4Cu10L12) (M = Mo, E = Se, L = PhCH2S (3)), MoFe3Se4 (mu-R2NCS2)2 (R2NCS2)4 have been prepared and characterized by UV, IR and X-ray diffraction analyses.

Copper↗
PubMed2002

Effectiveness of silver diamine fluoride and sodium fluoride varnish in arresting dentin caries in Chinese pre-school children.

Untreated dental caries in Chinese pre-school children is common. This prospective controlled clinical trial investigated the effectiveness of topical fluoride applications in arresting dentin caries. Three hundred seventy-five children, aged 3-5 years, with carious upper anterior teeth were divided into five groups. Children in the first and second groups received annual applications of silver diamine fluoride solution (44,800 ppm F). Sodium fluoride varnish (22,600 ppm F) was applied every three months to the lesions of children in the third and fourth groups. For children in the first and third groups, soft carious tissues were removed prior to fluoride application. The fifth group was the control. Three hundred eight children were followed for 30 months. The respective mean numbers of arrested carious tooth surfaces in the five groups were 2.5, 2.8, 1.5, 1.5, and 1.3 (p < 0.001). Silver diamine fluoride was found to be effective in arresting dentin caries in primary anterior teeth in pre-school children.

Analysis of Variance↗
PubMed2005

Bayesian analysis of clustered interval-censored data.

The recording of multiple interval-censored failure times is common in dental research. Modeling multilevel data has been a difficult task. This paper aims to use the Bayesian approach to analyze a set of multilevel clustered interval-censored data from a clinical study to investigate the effectiveness of silver diamine fluoride and sodium fluoride varnish in arresting active dentin caries in Chinese pre-school children. The time to arrest dentin caries on a surface was measured. A three-level random-effects Weibull regression model was used. Analysis was performed with WinBUGS. Results revealed a strong positive correlation (0.596) among the caries lesions' arrest times on different surfaces from the same child. The software WinBUGS made the above complicated estimation simple. In conclusion, the annual application of silver diamine fluoride on caries lesions, and caries removal before the application, were found to shorten the arrest time.

Bayes Theorem↗
PubMedDate not supplied

Etiologic factors and pathologic alterations in selenium-vitamin E deficiency and excess in animals and humans.

The etiology of selenium-vitamin E (Se-E) deficiency diseases may be complex. Many of the syndromes involve combined deficiency of selenium and vitamin E. Selenium moves into the animal and human food chain from soil and plants, which may contain inadequate amounts of the nutrient in many areas of the world. Vitamin E may be in low concentration in many animal feeds unless supplements are added. Some syndromes, such as steatitis in cats, result from an increased requirement of vitamin E in diets that contain large amounts of polyunsaturated fatty acids, and these diseases will only respond to vitamin E administration. Deficiency syndromes in animals owing to pure Se deficiency are infrequent and have been produced mainly by laboratory studies utilizing extreme deficiency conditions. Other factors that may affect the occurrence of these deficiency diseases are concurrent dietary deficiency of S-containing amino acids, bioavailability of different forms of dietary Se, intake of compounds that antagonize Se (e.g., silver salts), and exposure to various prooxidant substances (e.g., iron compounds, oxygen, ozone, and various drugs).

Animals↗