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At least 649 records · Page 36Linked to original sources
PubMed2005

Study on the immobilization of anti-IgG on Au-colloid modified gold electrode via potentiometric immunosensor, cyclic voltammetry, and electrochemical impedance techniques.

The immobilization of anti-IgG on Au-colloid modified gold electrodes has been investigated. A cleaned gold electrode was first immersed in a mercaptoethylamine (AET) solution, and then gold nanoparticles were chemisorbed onto the thiol groups of the mercaptoethylamine. Finally, anti-IgG was adsorbed onto the surface of the gold nanoparticles. Potentiometric immunosensor, cyclic voltammetry, and electrochemical impedance techniques were used to investigate the immobilization of anti-IgG on Au colloids. In the impedance spectroscopic study, an obvious difference of the electron transfer resistance between the Au-colloid modified electrode and the bare gold electrode was observed. The cyclic voltammogram tends to be more irreversible with increased anti-IgG concentration. Using the potentiometric immunosensor, the proposed technique is based on that the specific agglutination of antibody-coated gold nanoparticles, averaging 16 nm in diameter, in the presence of the corresponding antigen causes a potential change that is monitored by a potentiometry. It is found that the developed immunoagglutination assay system is sensitive to the concentration of IgG antigen as low as 12 ng mL(-1). Experimental results showed that the developed technique is in satisfactory agreement with the ELISA method, and that gold nanoparticles can be used as a biocompatible matrix for antibody or antigen immobilization.

Biocompatible Materials↗
PubMed2004

Aggregation of photolytic gold nanoparticles at the surface of chitosan films.

Formation and aggregation of photolytic gold nanoparticles at the surface of chitosan (CTO) films have been investigated. When thin films of chloroauric acid salt of CTO were irradiated with UV light in wet air at room temperature for 10 min, gold nanoparticles of approximately 10 nm size are formed at the film surface. Detailed X-ray photoelectron spectroscopy (XPS) study and field emission type scanning electron microscopy (FE-SEM) observation have been carried out to characterize gold nanoparticles at the film surface. The shift of Au(4f) peak to the higher energy side and broadening of full width at half-maximum in the XPS spectrum are the direct evidence of the existence of gold atoms and small clusters in the early stage of photolysis. According to FE-SEM observation, growth in the particle diameter and aggregation of nanoparticles were observed after prolonged irradiation, and, finally, the film surface was densely covered with gold particles of 20-100-nm size. Gold atoms and clusters could move in the film and precipitate to the irradiated surface. Chemical composition analysis further suggests that gold particles at the surface are covered with an ultrathin CTO layer, which is partly oxidized by oxygen and chlorinated by chlorine during photochemical reactions.

Air↗
PubMed2001

Multicenter study of the frequency of contact allergy to gold.

Gold sodium thiosulfate (GSTS) is reputed to be the most reliable gold antigen, but control studies are still required. Although Koreans have more varied sources of contact with gold, such as herbal medicines with gold coatings and indwelling gold acupuncture needles, no epidemiological studies have been performed. This study examined the frequency and sources of contact allergy to gold in South Korea by a multicenter study. Patch testing with 0.5% GSTS in pet. was conducted in 255 eczema patients and 58 control subjects. Results were observed at 21 days (D) to ensure there were no undetected late reactions in 54 observed patients and 47 controls. 8 (3.1%) of the 255 patients reacted positively to GSTS, including 1 with a late reaction. 1 of the 58 controls showed a positive reaction to GSTS on D4 with a negative reaction on D14. Clinical relevance was lacking in the patients with positive reactions. Unexpectedly, the above particular sources of gold contact gave rise to few allergic reactions in our patients.

Adolescent↗
PubMed1980

[Pharmacokinetics of gold after administration of aurokeratinate (author's transl)].

Aurokeratinate (Auro-Detoxin) was administered intramuscularly to patients with chronic rheumatoid arthritis, using two different dosage schedules and measuring serum gold concentration. (1) Using slowly rising doses (as generally practised) the gold level gradually rose to 3.2 microgram/ml after four weeks (before the ninth injection), without reaching cumulation equilibrium. Elimination from serum occurred during this phase, with a half-life of 3-5 days. When treatment was continued at about 25 mg gold twice weekly, the cumulation equilibrium was reached with a minimal value at 3.5 microgram/ml and a maximal one of 6 microgram/ml, elimination half-life then being increased to nine days. During the subsequent maintenance treatment with 65 mg gold once a month the serum-gold concentration fell to about 1 microgram/ml, maximal values being about 6 microgram/ml, with an elimination half-life of 11 days. (2) With a constant dose of about 25 mg gold twice weekly, cumulation equilibrium was reached after two weeks (3.4 microgram/ml before the fifth injection), while on 50 mg gold every 14 days as maintenance dose the serum concentration was between 2 microgram/ml minimally and 6 microgram/ml maximally. At the modified dosage the drug was well tolerated.

Arthritis, Rheumatoid↗
PubMed1984

Gold sensitivity blast transformation.

A 36-year-old female patient developed eczema from wearing gold jewelry. Epicutaneous skin tests were performed with gold leaf, potassium dicyanoaurate, gold sodium thiosulphate, gold chloride, sodium chloroaurate and potassium bromoaurate. The test was positive with gold sodium thiosulphate only. Blast transformation was induced with all the gold salts except sodium chloroaurate, and the positive responses seemed to be dose-dependent. In vitro gold salt-induced reactions are useful in the diagnosis of allergic contact dermatitis.

Adult↗
PubMed1997

Contact allergy to gold sodium thiosulfate. A comparative study.

During 1995, we added gold sodium thiosulfate and potassium dicyanoaurate to the patch test standard series. Our purpose was to compare the reactivity of the gold salts, to determine the frequency of contact allergy to gold in our country, to compare our results with those of the Malmö group and, finally to try to clarify the clinical relevance 2853 patients were routinely tested and 168 patients answered a questionnaire similar to that used by the Malmö group. Contact allergy to gold was found in 23 patients, all women: 22 to gold sodium thiosulfate (0.78%), only 1 to potassium dicyanoaurate and 2 to both salts. All reactors had their ears pierced and were exposed to gold jewelery (mainly earrings). Simultaneous allergies to nickel and cobalt were statistically significant in patients with positive patch tests to gold sodium thiosulfate. Atopy was no more common among these patients.

Chi-Square Distribution↗
PubMed1999

Gold--a controversial sensitizer. European Environmental and Contact Dermatitis Research Group.

Until recently, gold allergy was considered to be extremely rare. Gold has been used and worshipped for thousands of years without any obvious complaints of skin problems, either in those participating in mining and other ways of prospecting, or in those wearing jewellery. When studies on contact allergy to gold sodium thiosulfate were published at the beginning of the 1990s, the allergic nature of the reported positive patch test reactions to gold was questioned. The major argument for such questioning was the lack of demonstrable clinical relevance in most positive reactors. A major reason for the questioning may have been confusion in differentiating between contact allergy and allergic contact dermatitis. To arrive at a diagnosis of allergic contact dermatitis, 3 steps have, in principle, to be fulfilled: (i) establishment of contact allergy; (ii) demonstration of present exposure; (iii) assessment of clinical relevance, i.e., causing or aggravating a contact dermatitis. In this paper, these steps are discussed with regard to gold. With our present knowledge of contact allergy-allergic contact dermatitis, we do not recommend including gold sodium thiosulfate in the standard series. It should be applied for scientific purposes and when allergic contact dermatitis from gold is suspected.

Dermatitis, Allergic Contact↗
PubMed1983

Gold levels produced by treatment with auranofin and sodium aurothiomalate.

Sixty-three patients with rheumatoid arthritis were randomly divided into 3 groups, and treated with either sodium aurothiomalate (Myocrisin), auranofin, or placebo. Gold levels in whole blood, plasma, and haemolysate were measured serially along with clinical and laboratory parameters of efficacy. Auranofin produced a higher ratio of haemolysate to plasma gold than Myocrisin, and it appears that the affinity of the red cell for gold is reduced during therapy with auranofin. Gold levels did not correlate with changes in the pain score, erythrocyte sedimentation rate, and C-reactive protein, nor with the development of toxicity. In the Myocrisin group the haemolysate gold level achieved was dependent on the number of cigarettes smoked. In the auranofin group there was no such correlation, but the haemolysate gold level was higher for smokers than non-smokers. The likely action of gold is discussed.

Adult↗
PubMed1996

Flare-up at contact allergy sites in a gold-treated rheumatic patient.

Contact allergy to gold sodium thiosulfate and gold sodium thiomalate was established by skin testing in a rheumatic patient intended for gold therapy. An intramuscular test dose of gold sodium thiomalate (Myocrisin) induced a flare-up of previously positive epicutaneous and intradermal test reactions, with a histological and immunohistochemical picture compatible with an allergic contact dermatitis. Since gold allergy is frequent, the cutaneous side-effects of gold therapy ("gold dermatitis") may be explained by such an immunopathological reaction.

Antirheumatic Agents↗
PubMed1985

Acquired resistance against gold(III)-chloride in cultured human cells.

Acquired resistance against gold(III)-chloride was developed in cultures of human epithelial cells derived from normal skin, by growing them with stepwise increased concentrations of the compound in the medium. Resistance to 350 mumol gold-chloride/l, about twice the commonly tolerated concentration and an otherwise lethal concentration to the cells, was attained after an adaptation period of 2-3 months. These cells had preserved their normal appearance except from small inclusion bodies in the cytoplasm. The effect of 350 mumol gold-chloride/l culture medium on cell growth of the sensitive (HE) and resistant (HEAu350) cell strain, was tested over a period of 9 days. On day 9, 2% of the HE cells and 80% of the HEAu350 cells remained adherent to the flasks compared with their nontreated control cells. The doubling time of the HE cells grown without gold was 24 h, that of the HEAu350 cells grown continuously on 350 mumol/l was 36 h. The HE cells died on prolonged exposure to this concentration. Measurement of the cellular content of Au, Cu and Zn by atomic absorption spectrophotometry revealed that the HEAu350 cells contained 1.8 times as much cellular and cytosolic Au per mg cell protein as the HE cells. Sixty per cent of the cytosolic gold in the HEAu350 cells was bound to high molecular weight proteins; no metallothionein was detected. Both strains contained minor amounts of zinc and copper compared with gold. The HEAu350 cells contained twice as much cellular Cu/mg cell protein as the HE cells, whereas the zinc content remained unchanged. The mechanism of acquired resistance against gold-chloride in these cells remains unknown.(ABSTRACT TRUNCATED AT 250 WORDS)

Cells, Cultured↗
PubMed2002

[Spectroscopic studies on electrostatically self-assembled gold nanoparticulate thin films].

Colloidal gold was prepared by citrate-induced reduction of hydrogen tetrachloroaurate. Gold nanoparticulate thin films were built up using the electrostatic self-assembly technique and characterized by different spectroscopes. The UV-Vis absorbance spectrum indicated that the gold colloid was a monodisperse suspension. The calculation using the Scherrer's equation on base of the X-ray diffraction spectrum indicated that the average size of the gold particles assembled on the substrates was about 21 nm. The X-ray photoelectron spectra showed that the reduction of hydrogen tetrachloroaurate was almost complete and that the gold was present in the thin films largely as Au zero. The X-ray photoelectron spectra also showed that the gold particles were attracted and fixed onto the PDDA-modified substrates by electrostatic forces. The UV-Vis absorbance spectra and the surface enhanced Raman scattering spectra indicated that, arising from the interparticle coupling, the gold nanoparticulate thin films displayed strong collective plasma resonance absorption and sur faced enhanced Raman scattering effect.

Colloids↗
PubMed2006

[Research on development of gold immunochromagraphic assay test kit for serum Coxsackievirus IgM antibody.].

BACKGROUND: To develop gold immunochromatographic assay (GICA) test kit for serum Coxsackievirus IgM antibody and optimize the key experiment conditions. METHODS: Colloidal gold particles of 20 nm were prepared and coupled with sheep anti-human IgM, the gold immunochromatography assay test kit was setup for serum Coxsackievirus IgM antibody. RESULTS: The spheroidal colloid gold particles of 20 nm showed bright red in color. The minimal stable concentration (MSC) of gold sheep anti-human IgM was 1 ug/ml, and the suitable stable concentration (SSC) was 1.5 ug/ml. The pH 8.2 was appropriate; 30 sera samples were tested by GICA and ELISA, there was no significant difference between the two methods. CONCLUSION: The quality of gold immunochromatography assay test kit is associated with such factors as the quality and quantity of antigen or antibody, colloid gold particles, buffers, etc.

Chromatography, Affinity↗
PubMedDate not supplied

The influence of cigarette smoking on blood gold distribution during chrysotherapy.

Plasma and erythrocyte gold concentrations were measured in 35 patients taking gold sodium thiomalate (GSTM) for rheumatoid arthritis. In 6 patients with adverse effects attributable to gold therapy at the time of sampling, gold concentrations in plasma and erythrocyte fractions were no different from those without adverse effects. A significant difference was seen in the distribution of gold in the blood of cigarette smokers compared to non-smokers, with smokers having higher erythrocyte and lower plasma gold concentrations. A prospective study on 15 patients commencing treatment with GSTM showed that the higher concentrations of erythrocyte gold seen in smokers were achieved within the first 2 weeks of treatment.

Arthritis, Rheumatoid↗
PubMed1998

Treatment of pemphigus with gold.

BACKGROUND: Although gold has been reported to be useful in treating pemphigus vulgaris, its use has waned in recent years because of concerns regarding efficacy and toxicity. OBJECTIVE: To review 26 patients with pemphigus who were treated with intramuscular gold over a 10-year period. RESULTS: Gold was effective in 62% of patients as a primary treatment for pemphigus or as a steroid-sparing agent. An average of 3 months of therapy was required before the daily prednisone dosage could be halved. Four patients were free of disease and stopped receiving all therapy at the conclusion of the study. Toxic effects due to gold therapy developed in 42% of patients and all adverse effects resolved with its cessation. CONCLUSIONS: While toxic effects limit the use of gold in many patients with pemphigus, it may be effective in treating a large percentage of patients who otherwise are unable to reduce their steroid requirement. Because of its delayed onset of action, patients treated with gold usually require systemic steroids when therapy is initiated. Controlled, prospective trials are needed to further evaluate the efficacy of gold and its potential steroid-sparing effects.

Adult↗
PubMedDate not supplied

Some improvement in tissue preparation and colloidal-gold immunolabeling for electron microscopy.

The application of freeze-substitution (FS) and freeze-drying (FD) techniques and the protein A-gold-antibody complex immunocytochemical methods are described. The two tissue-preparation techniques produced excellent ultrastructure and topographical fixation of antigens when compared with conventional tissue-preparation techniques. In the FS preparation, however, occasional extragranular immunolabeling was recognized. This may suggest the leakage of antigens from the secretory granules. The FD procedure was considered the best, since such labeling was almost negligible. The protein A-gold-antibody complexes are easily prepared and label the antigens clearly. If the protein A-coated gold particles are saturated with antibodies, there is no interaction between gold particles. Thus, multiple antigens can be determined even in single secretory granules. In fact, we demonstrated intragranular colocalization of immunoreactive oxytocin, labeled with 50-nm gold particles, and immunoreactive methionine-enkephalin, labeled with 15-nm gold particles, in the axonal terminals of the FD-prepared rat neurohypophysis. This study demonstrates the value of the use of gold-antibody complexes for immunocytochemical labeling on FS- or FD-treated tissues.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Localization and quantification of hormones, ligands, and mRNA with affinity-gold probes.

The application of immunogold techniques to localize pituitary hormones produces label that can be quantified and correlated with different secretory states. This report focuses on three major applications of the technology. In the first set of studies, immunogold labels for adrenocorticotropin (ACTH) or luteinizing hormone (LH beta) and follicle-stimulating hormone (FSH beta) were applied to ultrathin sections of pituitaries from adrenalectomized rats or from rats in different stages of the estrous cycle. During the first week after adrenalectomy, ACTH cell area increased. The concentration of immunoperoxidase label (amount of label/area of the corticotropes) decreased. Counts of gold markers showed that there were no changes in the concentration of antigens per granule. Three weeks after adrenalectomy, the amount of immunoperoxidase label increased along with the concentration of that label. The concentration of gold label for ACTH on granules also increased. All changes correlated well with increases in serum ACTH stimulated by adrenalectomy. In the studies of cycling rats, gonadotropes showed increases in the number of gold markers for LH beta or FSH beta per granule area just before an elevation in serum levels. There were also increases in the proportion of granules that contained only LH beta or FSH beta (monohormonal) before the rise in secretion. Thus, nonparallel release of gonadotropins might be attributed to changes in the ratio of gonadotropins packaged per granule. In the second series of studies, avidin-gold labels were used to identify sites of binding of biotinylated ligands. These studies illustrate and quantify binding by biotinylated gonadotropin-releasing hormone (GnRH) to ovarian or pituitary target cells. Triple-labeling protocols (avidin-peroxidase followed by immunogold) show that the target cells in the pituitary contain gonadotropins. In the third set of studies, avidin gold or avidin peroxidase was used to label sites of hybridization of a biotinylated cRNA probe to gonadotropin beta subunit mRNA. The sites of hybridization appear on rough endoplasmic reticulum; however, further work is needed to improve cell ultrastructure and perserve antigens. Triple-labeling protocols (avidin-peroxidase followed by immunogold) show the feasibility of the technique as well as the need for further refinement. To summarize, these studies describe multiple applications of gold labels for the localization of antigens, ligands, and mRNA. The labels are sensitive for detection of antigens and ligands and easily quantified. Quantitative analyses show changes in concentration of gold label that correlate well with secretory states.

Adrenalectomy↗
PubMedDate not supplied

Comparison of detecting sensitivities of different sizes of gold particles with electron-microscopic immunogold staining using atrial natriuretic peptide in rat atria as a model.

The detecting sensitivities of different-sized gold particles were compared in the localization of atrial natriuretic peptide (ANP) in rat atria. The secondary antibodies were goat antirabbit labeled with 5, 15, 30, or 40 nm colloidal gold diluted 1:2 to 1:100 in Tris buffer. The relative quantity of alpha-ANP immunoreactivity in specific granules was determined by subtracting the number of gold particles in 1 micron 2 nongranule area from that in 1 micron 2 granule area measured with a computerized image analyzer. The optimal dilution that achieved the maximal contrast between specific and background label was influenced by the particle size. Optimal dilutions were 1:80, 1:30, 1:20, and 1:5 for 5, 15, 30, and 40 nm gold, respectively. At optimal dilutions, the maximal detecting sensitivity (MDS) was in inverse proportion to the gold particle size; however, this relationship is not entirely linear. The ratio among the MDSs of 5, 15, 30, and 40 nm gold particles was approximately 34:9:3:2. A double immunogold staining was performed to localize alpha- and beta-ANPs with 15 and 5 nm gold, respectively. Both antigens were detected in the same granules. If the ratios established from the single staining data were used, the ratio between the alpha- and the beta-ANP antigens in the same granules was approximately 2.8:1. The data obtained in this study provide a useful reference for applications of immunogold electron microscopy in a quantitative manner, particularly for double immunogold labeling.

Animals↗
PubMedDate not supplied

Ocular chrysiasis correlated with gold concentrations in the crystalline lens during chrysotherapy.

The eyes of 11 patients with rheumatoid arthritis (RA) who received extended chrysotherapy (mean cumulative dose greater than 7 grams during a mean 6-year period) were examined biomicroscopically. Minute reddish-purple particles were seen in the cornea (corneal chrysiasis) in 5 and in the lens (lens chrysiasis) in 4 patients. Particulate deposits were absent in 11 other RA patients who had not received gold treatment. Seven crystalline lenses from 5 gold-treated patients were removed surgically because of incidental cataract formation and analyzed for gold content using neutron activation analysis. Although the mean lens gold concentration was higher in these patients than in non-gold-treated controls without RA (0.0073 microgram/grams versus 0.001 microgram/grams), the absolute gold level was markedly lower than that found in 25 diverse tissue analyzed previously. This finding is compatible with the absence of clinical gold-related lens disease or visual impairment.

Adult↗