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At least 829 records · Page 46Linked to original sources
PubMed1977

Fenoprofen, aspirin, and gold induction in rheumatoid arthritis.

Fenoprofen calcium (2,400 mg/day) or aspirin (3,900 mg/day) was administered in double-blind fashion to 20 rheumatoid patients during 6 months of gold induction therapy, and to 20 rheumatoid patients not receiving gold. Among both the gold-treated and nongold-treated patients, the fenoprofen and aspirin groups improved equally in all but one parameter of disease activity. Fenoprofen and aspirin did not differ significantly in the observed prevalences of abdominal discomfort, guaiac-positive stools, or peptic ulcers. Aspirin was associated with significantly higher mean serum glutamic oxaloacetic transaminase (SGOT) levels than fenoprofen, but only among patients undergoing gold induction. Comparison of efficacy parameters between patients treated with gold and patients treated with oral drugs alone revealed significant differences favoring gold.

Adult↗
PubMed1979

Acid dissociation and metal complex formation constants of penicillamine, cysteine, and antiarthritic gold complexes at simulated biological conditions.

Ionization constants for acid functions of D-penicillamine, L-cysteine, thiomalic acid, and thioglucose were measured by pH titration at 37 degrees and 0.15 M ionic strength. Chelate formation constants for these ligands with calcium(II), iron(III), and gold(I) were then determined under the same conditions chosen to approximate the in vivo situation. Only iron(III) formed both 1:1 and 1:2 chelates with D-penicillamine, L-cysteine, and thiomalate; calcium formed weak and gold strong 1:1 complexes with all ligands studied. Because of precipitate formation, the stability constants for the systems thioglucose-iron(III), D-penicillamine-gold(I), and L-cysteine-gold(I) had to be determined indirectly with thiomalic acid as the competing ligand. The in vivo fate of antiarthritic gold(I) compounds remained uncertain, but gold(I) chelates probably persist as such for extended periods.

Acids↗
PubMed1980

Binding of gold to bovine serum albumin using flameless atomic absorption.

A graphite furnace atomic absorption spectrophotometric assay capable of accurately determining nanogram amounts of gold in biological fluids was developed. The presence of bovine serum albumin and/or phosphate in the sample reduced the method sensitivity without affecting the linear response. Binding of gold was studied by ultrafiltration using cones with a molecular weihght cutoff of 25,000. The binding of gold at various concentrations to 2 and 4% bovine serum albumin in 0.1 M phosphate buffer, pH 7.4, was independent of the gold and protein concentrations. In the 2-10 microgram/ml range, the overall binding values (mean +/- SD) of gold to 2 and 4% bovine serum albumin were 98 +/- 1.6 (n = 35) and 99 +/- 1.0% (n = 15), respectively. When ultrafiltration cones with a molecular weight cutoff of 50,000 were used, the extent of binding to 2% bovine serum albumin was 85.4 +/- 1.6% (n=11). This statistically significant difference (p less than 0.001) was due to variations in the protein retention of the two cone types. Interaction studies showed that gold was not displaced from the binding sites by salicylic acid (200 microgram/ml) or vice versa.

Animals↗
PubMed2001

Interactions of selected gold(III) complexes with calf thymus DNA.

DNA represents the primary target for platinum antitumor metal complexes and is the probable target for newly developed cytotoxic gold(III) complexes. To test this hypothesis the reactions with calf thymus DNA of five representative gold(III) complexes--namely [Au(en)(2)]Cl(3), [Au(dien)Cl]Cl(2), [Au(cyclam)](ClO(4))(2)Cl, [Au(terpy)Cl]Cl(2) and [Au(phen)Cl(2)]Cl--were analyzed in vitro through various physicochemical techniques including circular dichroism, absorption spectroscopy, DNA melting, and ultradialysis. It is shown that all tested complexes interact with DNA and modify significantly its solution behavior. The solution conformation of DNA is affected to variable extents by the individual complexes as shown by CD titration experiments. Notably, in all cases, the gold(III) chromophore is not largely perturbed by addition of calf thymus DNA ruling out occurrence of gold(III) reduction. Ultradialysis experiments point out that the binding affinity of the various complexes for the DNA double helix is relatively low; in most cases the gold(III)/DNA interaction is electrostatic in nature and reversible. The implications of these findings for the mechanism of action of antitumor gold(III) complexes are discussed.

Animals↗
PubMed1998

Mercury exposure of maroon workers in the small scale gold mining in Suriname.

Suriname is experiencing a revival of small scale gold mining activities, with about 10,000 to 15,000 workers involved in 1996. The estimated production in 1995 is at least 10,000 kg crude gold. Gold is extracted with mercury and methods used are comparable with those described for gold mining in the Amazon Basin. Since no data exist on the internal mercury exposure of workers in Suriname a study was performed. A group of mercury-exposed Maroons, who are principally involved in the mining located in the tropical rainforest, is compared with nonexposed Maroons living in a non-gold mining area. Blood and urine samples of both groups were analyzed for total mercury using an atomic absorption spectrometer with an FIAS hydride system. In the study 28 exposed and 17 controls with a comparable mean age (P=0.544; exposed 27+/-7.2 years, n=26; controls 26+/-7.7 years, n=17), all males, participated. The urine levels for both groups differ statistically significantly from each other (P<0.001; exposed mean 27.5+/-21.1 microg/g creatinine; controls mean 5. 2+/-2.9 microg/g creatinine). This is, however, not the case with the blood levels (P=0.036: exposed mean 18.1+/-11.0 microg/L, n=25; controls mean 26.8+/-14.6 microg/L, n=16). In contrast with blood the urine total mercury levels in this study confirm, on a group basis, exposure to mercury as described for individuals working in the gold mining in the Amazon Basin.

Adolescent↗
PubMed1999

Gold-tagged RNA-A probe for macromolecular assemblies.

Ribonucleic acids (RNAs) play a key role in many fundamental life processes. These polymers are often found complexed with proteins in extremely large particles whose molecular mass may reach several millions of daltons (e.g., ribosomes, spliceosomes, and viruses). Structural studies of such RNA-protein complexes should help elucidate their mode of action. For the structural analyses of many macromolecular assemblies, electron microscopy (EM) has served an instrumental role. However, localization by EM of RNA within biological complexes is not yet a straightforward undertaking. Here we describe a methodology for the covalent tagging of RNA molecules with gold clusters, thereby enabling their direct visualization by microscopical methods. Our strategy involves transcription in vitro of RNAs that carry free thiol groups, using ribonucleoside triphosphate analogs containing a substituent with a terminal thiol group on their heterocyclic ring. This synthesis is followed by coupling of gold clusters to the thiolated transcript through a maleimido group. Visualization of such gold-tagged RNAs by transmission electron microscopy showed spots of gold clusters, with a diameter of 1-2 nm, arranged at nearly regular distances on an imaginary curve that presumably corresponds to the RNA chain. This assignment was corroborated by atomic force microscopy that exhibited images of RNA chains in which knob-like structures, whose height corresponds to the diameter of the gold clusters, were clearly seen. This study demonstrates the potential use of nucleic acids that are covalently labeled with gold clusters for the structural characterization of protein-RNA complexes.

Globins↗
PubMed1984

Labelling of colloidal gold with protein. A quantitative study using beta-lactoglobulin.

Markers prepared by labelling colloidal gold with macromolecules such as lectins, antibodies and protein A are gaining wide acceptance both in transmission and scanning electron microscopy. However detailed information on the process and extent of adsorption of macromolecules onto gold particles are still lacking. The adsorption isotherm of protein onto gold particles was studied quantitatively using goat beta-lactoglobulin (beta L) tritiated in vivo. When this protein was modified chemically by iodination with 125I, the adsorption isotherm was not significantly different (Langmuir type for monolayer). In the presence of saturating amount of beta L, a maximum of 13-14 molecules was adsorbed per particle of 12 nm in diameter for a theoretical maximum of 20 (compact monolayer). Ellipsometric measurements on nickel-coated slides indicated that betas L was adsorbed onto metallic surfaces as a compact monolayer. The molecules were irreversibly adsorbed on gold particles, kept to a large extent their capacity to bind anti-beta L antibodies and could not be displaced by polyethylene glycol, a stabilizer commonly used in the preparation of gold markers. Only markers labelled with more than 5 beta L molecules per particle could be completely bound by immobilized anti-beta L antibodies. Preliminary data indicated that the energetics of adsorption of beta L onto colloidal gold was in agreement with that expected from the mutual interaction of surface and adsorbate.

Adsorption↗
PubMed1986

Controlled growth of colloidal gold particles and implications for labelling efficiency.

A new method is reported for the preparation of colloidal gold particles with diameters ranging between 5 and 12 nm. The initial gold particle population, with an average diameter of 5.6 +/- 0.9 nm, is prepared by reduction of chloroauric acid with white phosphorous. An increase in particle diameter by growth is obtained by reduction of chloroauric acid with white phosphorous in the presence of colloidal gold particles. The labelling efficiency of these gold particles, conjugated with protein A, in indirect immunolabelling experiments is investigated by labelling of beta-galactosidase on ultrathin cryosections of Escherichia coli cells. We demonstrate that the labelling efficiency is at least dependent on particle diameter, probe concentration and preparation method. In addition it is shown, that with this new method, gold particle populations can be prepared with minor overlap in diameter spreading. Therefore these gold probes are suitable for qualitative double labelling experiments. The quantitative aspect of immunolabelling is discussed.

Colloids↗
PubMed1982

Allergic contact gingivostomatitis due to gold.

The sixth case of an allergic contact gingivostomatitis to gold crowns previously misdiagnosed as erosive lichen planus is reported. Patch tests to gold chloride (0.5%) and 0.05 cm3 intradermal gold sodium thiomalate (Myochrysine 50 mg/cm3) were positive at 48-72 h. Histopathology of the allergic contact gingivitis revealed a pseudolymphomatous inflammatory dermal reaction with a dense lymphohistiocytic and plasma cell infiltrate. Removal of the gold crowns resulted in a gradual resolution of the gingivostomatitis in 4-6 months, and the patient has remained free of clinical disease for over 3 years. A review of the reported cases of allergic gingivostomatitis to gold crowns revealed that each patient clinically presented with an erosive and ulcerative inflammatory response was usually associated with a clinical history of gold jewelry intolerance.

Adult↗
PubMed1988

Elderberry bark lectin--gold techniques for the detection of Neu5Ac (alpha 2,6) Gal/GalNAc sequences: applications and limitations.

The lectin from the elderberry (Sambucus nigra L.) bark, shown to recognize the sequence neuraminic acid (alpha 2,6) galactose/N-acetylgalactosamine, was applied for detecting binding sites in Lowicryl K4M sections by light and electron microscopy. The lectin was used either directly complexed to colloidal gold or in a two-step cytochemical affinity technique. The lectin-gold complex proved to be superior and thus was extensively tested on rat liver, kidney and hepatoma cells as well as on sheep and bovine submandibular glands. Controls to establish specificity of lectin-gold binding included sugar and glycoprotein inhibition tests and enzymic removal of sialic acid. In agreement with biochemical data demonstrating the potentiating effect of sialic acid on the binding of the lectin to oligosaccharides, enzymic removal of sialic acid from liver sections resulted in abolition of lectin staining. However, in the submandibular glands, neuraminidase pretreatment of the sections had no effect on the subsequent lectin-gold binding. In rat kidney some structures became negative while others retained the lectin-gold staining due to binding to penultimate N-acetylgalactosamine exposed after sialic acid removal. In line with this, spot blot analysis demonstrated that the lectin-gold complex reacted with both fetuin and asialofetuin. Taken together, these results suggest that, for cytochemical staining, the sialic acid and the galactose/N-acetylgalactosamine lectin combining subsites of Sambucus nigra L. lectin are equally reactive with cellular glycoconjugates and that neuraminidase predigestion of tissue sections is of utmost importance to ensure specificity of staining for the sequence neuraminic acid (alpha 2,6) galactose/N-acetylgalactosamine.

Acetylgalactosamine↗
PubMed1991

Enzyme-gold cytochemistry of seed xyloglucans using two xyloglucan-specific hydrolases. Importance of prior heat-deactivation of the enzymes.

Two pure, homogeneous xyloglucan-hydrolyzing enzymes from germinated nasturtium seeds have been used to localize xyloglucans specifically in seed cell walls. The enzymes, a novel endo (1----4)-beta-D-glucanase which shows absolute specificity towards xyloglucans and a beta-D-galactosidase which is capable of removing galactosyl residues from polymeric xyloglucans, were used to stabilize gold sols. The complexes were applied to ultrathin sections of nasturtium (Tropaeolum majus L) and tamarind (Tamarindus indica L) seeds. The gold complexes prepared from the active enzyme proteins retained enzyme activity, and such complexes gave extremely weak section-labelling or no labelling at all. When the enzymes were subjected to heat-deactivation before being used to stabilize the gold sols, gold complexes were obtained which lacked enzyme activity, but which gave strong, specific labelling of xyloglucans in ultrathin sections. The specificity of the labelling was checked by substrate-competition, by pretreatment of sections with the active and heat-denaturated enzymes and by comparing the labelling of xyloglucan-containing storage cells with other cell types in the same section. The labelling was maximal at the pH which was optimal for the active enzyme. We conclude that the enzyme-gold complexes which retain high activity against the substrate to be localized are likely to be unsuitable as cytochemical probes because they may cause in situ substrate modification. In the case of the enzyme complexes described here the specific localization obtained with the gold complexes prepared from heat deactivated enzymes may be attributable to the retention by the heat-treated enzymatically-inactive proteins of substrate recognition.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1985

Ultrastructural localization of DNA and RNA in Allium porrum interphase cells by means of nuclease-gold complexes.

Nucleic acids have been localized in Allium porrum interphase meristematic cells by means of labelling with nuclease-gold complexes, a technique which provides high resolution and improved specificity. DNase-gold labelling was observed over dense chromatin and to a lesser extent over dispersed chromatin. Nucleolar labelling was restricted to the dense fibrillar component, very few particles being located over the fibrillar centres. Labelling by the RNase-gold complex was present over both the cytoplasm and the nucleoplasm. Cytoplasm labelling was intense over the rough endoplasmic reticulum but absent over vacuoles. In the nucleoplasm many gold particles were located at the border between the condensed and the dispersed chromatin. Nucleolar labelling was intense over the granular zones but many gold particles were also seen over the dense fibrillar component. Fibrillar centres showed, however, no labelling with the RNase-gold complex. These results are consistent with previous autoradiographic and cytochemical observations carried out on the same plant material.

Cell Nucleolus↗
PubMed1980

[Clinical trial in couples of effectiveness and side-effects of gold and D-penicillamine in long term treatment of rheumatoid arthritis (author's transl)].

A prospective clinical trial in couples was done to compare effectiveness and toxicity of gold and D-penicillamine (D-Pen.) in treatment of rheumatoid arthritis (r.A.). Respecting defined criteria 70 patients were put to couples according to a random list and were treated with gold or D-Pen. alternatively. Physical and laboratory indices of inflammatory activity were checked every 3 months, X-rays every 12 months. Dropouts (side effects, missing compliance, uneffectiveness) were replaced by the nextcoming fitting patient. Thirty-two of 147 totally recruited patients stopped treatment because of side effects, three because of unsatisfying efficiency. Forty-two patients shuned the necessary controls. The clinical course was better in 16 couples with gold, only in sex couples with D-Pen. Thirteen pairs showed no difference in this respect (p = 0.05). Looking to the laboratory parameters separately D-Pen. tends to be superior (p < 0.05), radiografic deterioration seems to be more seldom with gold (< 0.05). Side effects occur with both drugs in comparable frequency (15/44 with D-Pen., 17/52 with gold), but the complications with D-Pen. are more serious. Altogether this trial shows gold superior to D-Pen. in the long-term treatment of r.A.

Adult↗
PubMed1986

A double-blind study on the effect of discontinuation of gold therapy in patients with rheumatoid arthritis.

To assess the benefit of further gold treatment of rheumatoid arthritis (RA) patients who had already received more than 6 g of this metal, 24 such patients were included in a double-blind trial. Besides this "gold group" comprising 11 patients who received gold (Auromyose) in the same dosage schedule as before the study, the trial included a "placebo group" comprising 13 patients who received gold in a suspension diluted 1/100. In either group clinical, laboratory, and radiological data did not differ after 6 and 24 months in relation to the results at entry except for the serum gold concentrations, which were lower in the placebo group. We conclude that discontinuation of the treatment in RA patients who have received more than 6 g gold is not harmful to the patients for at least two years after withdrawal.

Aged↗
PubMed1987

Serum gold concentrations during treatment with auranofin.

Serum gold concentrations were measured in rheumatoid arthritis patients during chronic treatment with the orally adsorbable gold compound auranofin. In agreement with data in the literature, the highest serum gold concentration was reached after 16 weeks of treatment with 6 mg auranofin daily. A striking finding in this study was that thereafter the serum gold concentrations did not appear to plateau but declined gradually. Statistically this resulted in a significantly lower concentration after one year as compared with week 16 (p less than 0.05, paired t-test). It is suggested that a shift from protein bound gold to cell-bound gold might be the explanation.

Adult↗
PubMed2002

Decorated surfaces by biofunctionalized gold beads: application to cell adhesion studies.

We describe a simple but versatile method to decorate solid surfaces randomly with colloidal gold particles to which ligands of cell receptors can be coupled to generate local attraction sites for the control of cell adhesion. A self-assembled monolayer of (3-mercaptopropyl)trimethoxysilane was deposited on glass slides. Gold beads were anchored to the functionalized surface through the sulfur group. We characterized the gold bead distribution on the functionalized surface with reflection interference contrast microscopy. The gold beads were functionalized with a disulfide-coupled cyclic pentapeptide containing an arginine-glycine-aspartic acid (RGD) tripeptide sequence which is selectively recognized by integrin receptors alpha(V)beta(3) of endothelial cells. A blocking layer of bovine serum albumin was adsorbed onto the surface to prevent non-specific binding of the cells. We demonstrate that the RGD-functionalized colloidal gold beads act as local attraction centers, mediating rapid cell anchoring on a substrate impeding cell adhesion in the absence of attraction centers. Surprisingly, microinterferometry shows that after a time delay of about 1 h, the regions of the cell surface between the gold beads form close contacts with the substrate, which is attributed to strong van der Waals attraction after escape of repeller molecules from the contact surface.

Biophysics↗
PubMed1982

Sequential gold and penicillamine therapy in rheumatoid arthritis.

Ninety patients with rheumatoid arthritis who had received courses of gold followed by penicillamine for their disease were evaluated to determine the predictiveness of a certain response or adverse reaction to gold for the same response or adverse reaction to penicillamine. Most patients who were considered gold-responders also responded to penicillamine, and most patients who did not respond to gold responded to penicillamine as well. Regarding toxicity, gold reactions did not predict reactions to penicillamine except that that patients with gold-induced proteinuria were at a higher risk for development of proteinuria during penicillamine therapy (p less than 0.001), and this usually occurred within the first six months of treatment. Patients with penicillamine-associated mucocutaneous reactions tended to have low gamma globulin levels (p less than 0.05) and were less likely to have subcutaneous nodules (p less than 0.05).

Adult↗
PubMed1988

Inhibition of production of macrophage-derived angiogenic activity by the anti-rheumatic agents gold sodium thiomalate and auranofin.

We have investigated the effect of gold sodium thiomalate and auranofin, gold compounds employed in the treatment of rheumatoid arthritis, on production of macrophage-derived angiogenic activity. Elicited mouse peritoneal macrophages were cultured in the presence or absence of gold compounds or thiomalic acid, and the macrophages or their conditioned media were then assayed for their angiogenic activity in rat corneas. Control macrophage conditioned medium was potently angiogenic. In contrast, conditioned medium from gold or thiomalic acid treated macrophages was not. Addition of gold compounds or thiomalic acid to control macrophage conditioned medium did not inhibit its angiogenic activity. Drug treatments did not significantly affect macrophage lactate dehydrogenase release, lysozyme release, or protein synthesis. We conclude that gold sodium thiomalate and auranofin potently reduce the detectable angiogenic activity produced by macrophages.

Animals↗