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PubMed1987

Gold colitis induced by auranofin treatment of rheumatoid arthritis: case report and review of the literature.

A case of ulcerative colitis occurred during treatment of rheumatoid arthritis with the new oral gold preparation auranofin after a cumulative dose of 2160 mg. A barium enema showed loss of mucosal pattern and a rectal biopsy disclosed deep erosions, mucosal inflammation, and crypt abscesses. Precipitates of gold were seen in the periglandular stroma. On electron microscopy the gold deposits seemed to be identical to granules described in gold nephropathy. As the extrapolated serum gold level was within the normal range at the onset of the complication, the morphological findings suggested a local toxicity of the drug. The patient recovered within 14 days of withdrawal of auranofin and the start of therapy with sulphasalazine and steroids. A review of the published work shows that the previously reported mortality in gold colitis of 40% has decreased in recent years. The causes of this decrease may be both the earlier diagnosis of gold colitis and the improved intensive care of its severe complications.

Arthritis, Rheumatoid↗
PubMed1999

High-resolution immunocytochemical labeling of replicas with ultrasmall gold.

The use of 10-15-nm gold probes in freeze-fracture immunocytochemistry sometimes results in poor immunogold labeling. Replica sites are labeled with only one or two gold particles, making it unlikely that the labeling depicts the true distribution of antigen. In this study, the feasibility of using ultrasmall ( approximately 1.4-nm) gold probes for immunocytochemical labeling of replicas was examined. When HLA Class I in neutrophil membrane replicas was labeled with various sized immunogold particles as the secondary detection system, the apparent distribution density was inversely related to the size of the particles (1.4-nm > 5-nm >10-nm >15-nm). Indeed, the density of the apparent distribution of HLA Class I labeled with 1.4-nm gold particles was about sevenfold greater than when labeling was carried out with the 10-nm gold particles. Similar results were obtained with CD16, another neutrophil membrane protein. Silver enhancement was required to visualize the 1.4-nm gold particles, but this procedure did not adversely affect replica membranes. These results suggest that, when followed by silver enhancement, 1.4-nm gold particles are effective probes for achieving high-resolution immunocytochemical labeling of replicas.(J Histochem Cytochem 47:569-573, 1999)

Freeze Fracturing↗
PubMed1988

Gold probe choice in simultaneous detection of human lymphocyte surface antigens at the ultrastructural level.

A double immunogold-labeling method in immunoelectron microscopy was used for simultaneous detection of two antigens by monoclonal antibodies [OKT 8 (CD 8), anti-Leu-7, anti-Leu-11b (CD 16)] on lymphocytes in suspension. The combination of gold probe size (5 nm and 15 nm) and monoclonal antibody was found to be decisive for detecting double-labeled cells with the OKT 8+, Leu-11b+ phenotype. The combinations of OKT 8 labeled with the 5-nm gold probe (OKT 8(5] and anti-Leu-11b with the 15-nm gold probe (Leu-11b15) gave double-labeled cells; the reverse situation, using OKT 8 with a 15-nm gold probe (OKT 8(15] and anti-Leu-11b with a 5-nm gold probe (Leu-11b5), did not. Double-labeled OKT 8+, Leu-7+ cells were detected irrespective of which gold probe combination was applied. Our findings indicate that although the double immunogold-labeling method is well suited for study of lymphocyte subsets, it is important to determine suitable combinations of gold probe sizes and monoclonal antibodies for the lymphocyte subset under study, taking into account surface antigen density, so that double labeling ensues.

Antibodies, Monoclonal↗
PubMed1993

Enhancement of antigenic site detection with gold labeled secondary and tertiary antibodies using the immunogold-silver staining method.

We report a modification of the immunogold-silver staining method (IGSS) for localizing hepatic phosphoenolpyruvate carboxykinase (PEPCK) in tissue sections, and we compare the efficacy of localizing the primary antibody with either a 5 nm gold labeled secondary antibody or 5 nm gold labeled secondary and tertiary antibodies. Light microscope examination of 10 microns frozen sections demonstrated that the use of combined secondary and tertiary gold labeled antibodies was superior to using a secondary gold labeled antibody alone. The increased labeling density (number of colloidal gold particles/antigenic site/cell) achieved by combined gold labeled antibodies was confirmed by electron microscopy. The increased labeling density resulted in a two-thirds reduction in the time needed for the IGSS physical development of the silver shells and less background. We achieved intense specific staining of hepatocytes expressing PEPCK while minimizing background staining. The use of combined secondary and tertiary gold labeled antibodies enhances the signal-to-noise ratio, achieves high resolution and is a suitable method for use in both light and electron microscopy.

Animals↗
PubMedDate not supplied

Post-embedding double-gold labeling immunoelectron microscopic co-localization of neurotransmitters in the rat brain.

BACKGROUND: In this report, we describe a new quantitative electron microscopic protocol based on the use of double colloidal-gold post-embedding immunostaining procedure as markers to analyze the subcellular distribution of enkephalin (ENK) and GABA neurotransmitters simultaneously in the same ultrathin tissue sections in the periaqueductal gray area (PAG) of the rat brain. MATERIAL AND METHODS: Double gold particle signals were significantly improved using a number of technical adjustments for the immunogold electron microscopic co-localization technique of ENK and GABA. The GABA-like neuronal elements were immuno-reacted with 20 nm gold particles and the enkephalin-like immunoreactive neurons were labeled with 10 nm gold particles. This double labeling was more apparent in tissue sections that were deactivated for the gold staining of the first antibody. Excellent double labeling was obtained when we blocked antigenicity of the first antiserum with hot (80 degrees C) paraformaldehyde fumes. To minimize the clumping of the second gold particles around the first gold particles used against the first antibody, we tried different staining order for the neurotransmitters tested in this study. It was necessary to use a detergent (Triton X-100) at very low concentration (0.1%) instead of etching to expose the antigenic determinants of the neurotransmitters and at the same time to reduce the deleterious effects on the morphology of the tissue sections. Furthermore, the high-glutaraldehyde fixation and the decrease in the interval between cutting and labeling of the ultrathin sections significantly improved the results obtained in this study. RESULTS: Double labeling of sections with ENK and GABA produced co-localization in 23.1% and 1.2% of the immunoreactive axonal terminals and dendrites, respectively. Most of the double-labeled terminals contained more GABA-like than ENK-like immunolabeling. Half of the axon terminals [51%] and dendrites [56%] in the ventrolateral PAG were not labeled with either of GABA or ENK immunoreactivity. CONCLUSIONS: This procedure was found to be completely compatible with good double immunolabeling and ultrastructural preservation.

Animals↗
PubMed2005

['Gold standard', not 'golden standard'].

In medical literature, both 'gold standard' and 'golden standard' are employed to describe a reference test used for comparison with a novel method. The term 'gold standard' in its current sense in medical research was coined by Rudd in 1979, in reference to the monetary gold standard. In the same way that the monetary gold standard allowed for the comparison of different currencies, the medical gold standard allowed for the comparison of different diagnostic tests. Whereas the gold standard was never regarded as infallible, the incorrect term 'golden standard' implies a level of perfection that is unattainable in medical science. Consequently, the correct term should be 'gold standard'.

Diagnostic Tests, Routine↗
PubMed1991

Demonstration of the cytoskeleton of lens epithelial cells with gold sol techniques.

1. The Triton-extraction procedure is well suited for the demonstration of the cytoskeleton by TEM. A good preservation of the fine cytoskeletal network depends on optimal drying. 2. Immunogold-labeling is a useful method for visualization of intermediate filaments (IF) and microfilaments (MF). Labelled and unlabelled filaments are discernible. 3. Various methods were tested for a direct gold-labeling of MF with phallotoxin-gold preparations: The application of phalloidin-gold complexes results in an intensive unspecific staining of cytoskeletal filaments. A modified coupling procedure for the binding of phallacidin to transferrin was necessary to avoid the agglomeration of gold particles. The direct labeling of the cytoskeleton by the application of phallacidin-transferrin-gold complexes to Triton-extracted cells demonstrated an enrichment of gold particles on the both types of filaments, but MF and IF were not discernible. The treatment with phallacidin-polylysin-gold complexes demonstrated labelled filaments, but without sufficient intensity.

Actin Cytoskeleton↗
PubMed1989

Brief review on progresses in enzyme-gold cytochemistry.

Initially developed for the in situ localization of nucleic acids, the enzyme-gold approach has been extended to the detection of a large variety of biological molecules. The enzyme-gold approach, based on the highly specific interaction existing between an enzyme and its substrate, can be used both in pre-embedding and post-embedding labeling procedures. Fixation and embedding conditions for the best preservation of each particular substrate under study have to be defined. On the other hand, conditions required to adsorb purified enzymes on colloidal gold particles should be determined according to the biochemical properties of each protein. Labeling protocols must be performed taking into consideration the optimal conditions for the enzymatic activity. The enzyme-gold complexes have been shown to retain their biochemical properties and the specificity of each labeling obtained has been assessed through various control experiments. Initially applied for the demonstration of nucleic acids, the approach has been extended to the ultrastructural localization of various substrates, and in particular, more recently, glycoconjugates and phospholipids. Indeed, various glycosidase-gold complexes and a phospholipase-gold complex, applied in pre- and post-embedding labeling protocols, did specifically label plasma membranes as well as various defined subcellular compartments. In addition, the morphometrical evaluation of labeling intensities revealed differences in amounts of binding sites between compartments. Considering its versatility, simplicity and efficiency, the enzyme-gold technique provides an alternative, very valuable cytochemical tool for the localization of a variety of biological molecules at the cellular and subcellular level.

Animals↗
PubMed1995

How low can you go? Use of very low dosage of gold in patients with mucocutaneous reactions.

OBJECTIVE: We identified a group of patients with rheumatoid arthritis (RA) who were sensitive to both the beneficial and the side effects of intramuscular (im) gold treatment and whose disease was well controlled with doses of gold between 2 mg every 6 weeks and 5 mg weekly. We describe the clinical course of these patients and their management aimed at maximizing the effectiveness of gold therapy. METHODS: Patients successfully treated with maintenance doses of im gold (< 20 mg/mo and not more than 10 mg/dose) were identified by chart review. Clinic records were reviewed to extract clinical and laboratory data. RESULTS: The population consisted of 11 female and 2 male patients with RA. Eleven were seropositive and 2 had Felty's syndrome. All developed mucocutaneous side effects within 20 weeks of beginning im gold therapy, at a time when RA had improved markedly compared to pretreatment status. Side effects recurred with sequential dosage adjustments so that doses > 10 mg were not tolerated. Side effects were managed by temporary discontinuation of gold until side effects resolved and resumption of treatment using usually 50% lower dosage. When side effects recurred the dosage was reduced further by 50%. Final maintenance dose was 2 mg every 4 weeks in 1 patient, 2 mg weekly in 1, 3 mg weekly in 3, 5 mg monthly in 1, 10 mg every 3 weeks in 2, 10 mg every 4 weeks in 2, 10 mg every 6 weeks in 1, and 5 mg weekly in 2 patients. All patients improved and 6 are in complete remission. Mean duration of therapy was 5.5 yrs. CONCLUSION: The minimum effective dose of im gold is not known. Dose and dose intervals should be individualized for optimal benefits and tolerability.

Adult↗
PubMedDate not supplied

[Mechanism of action of gold in treatment of rheumatoid arthritis].

Gold is one of the oldest and most effective drugs in the treatment of rheumatoid arthritis. Gold unfolds its therapeutic efficacy through various influences on the immune system. Gold alters antigen-processing and reduces cytokine expression of macrophages. Additionally, gold reduces adhesion molecules, antibody production and inhibits proteolytic enzymes. However, macrophages also oxidize gold(I) to gold(III) which is - by its increased protein reactivity - responsible for a large part of the gold side-effects.

Antirheumatic Agents↗
PubMed2025

Homogeneous Gold Catalysis: Development and Recent Advances.

Gold catalysis has witnessed remarkable advances over the past decade, with numerous insightful reviews chronicling this progress. However, a comprehensive review addressing developments in the field during the post-pandemic COVID era remains notably absent. This review aims to bridge that gap by providing an in-depth analysis of recent studies, shedding light on the unique properties of gold complexes, particularly the intriguing aurophilic interactions that distinguish gold chemistry. The review systematically explores the latest achievements in both mono- and dinuclear gold-catalyzed reactions, with a focus on their applications in diverse fields, including redox coupling, asymmetric catalysis, photo-, and electrocatalysis. A special emphasis is placed on the comparative performance of mono- and dinuclear gold catalysts, with the latter often exhibiting enhanced catalytic efficiency and selectivity in certain reactions. By integrating mechanistic insights and DFT perspectives with representative experimental studies from recent years, this review highlights the significance of gold catalysis to synthetic chemistry, identifies emerging trends and outlines future directions for the field.

Catalysis↗
PubMedDate not supplied

The pharmacokinetics of intramuscular gold sodium thiomalate in normal volunteers.

Four normal male volunteers participated in a study designed to examine the disposition of gold given intramuscularly as gold sodium thiomalate. Blood samples were collected for 32 days following the administration of 10 mg of gold sodium thiomalate. Plasma gold concentrations were determined by atomic absorption spectrometry. A triphasic decay pattern in plasma gold concentrations was observed. Terminal log-linear phases corresponded to a mean disposition half-life of 25 days. Apparent total body clearance of gold was 7.0 +/- 0.6 ml kg-1 day-1 and the apparent volume of distribution was 0.26 +/- 0.051 kg-1. These pharmacokinetic data are in contrast to previous data from other investigators who have reported half-lives of approximately 5 days. Data from the current study provide a sound rationale for the currently used empiric dosing regimens.

Adult↗
PubMed2006

A mass spectrometric investigation of the binding of gold antiarthritic agents and the metabolite [Au(CN)2]- to human serum albumin.

Electrospray ionisation (ESI) mass spectrometry was used to examine the reactions of the clinically used antiarthritic agent [Au(S2O3)2]3-, and AuPEt3Cl, a derivative of another clinically used agent auranofin, with human serum albumin (HSA) obtained from a human volunteer. Both compounds reacted readily with HSA to form complexes containing one or more covalently attached gold fragments. In the case of AuPEt3Cl, binding was accompanied by the loss of the chloride ligand, while for [Au(S2O3)2]3- the mass spectral data indicated binding of Au(S2O3) groups. Experiments performed using HSA with Cys34 blocked by reaction with iodoacetamide were consistent with reaction of both gold compounds with this amino acid. Separate blocking experiments using diethylpyrocarbonate and AuPEt3Cl also provided evidence for histidine residues acting as lower-affinity binding sites for this gold compound. ESI mass spectra of solutions containing [Au(S2O3)2]3- or [Au(CN)2]-, and HSA, provided evidence for the formation of protein complexes in which intact gold molecules were non-covalently bound. In the case of [Au(S2O3)2]3-, these non-covalent complexes proved to be transitory in nature. However, for [Au(CN)2]- a non-covalent complex containing a single gold molecule bound to HSA was found to be stable, and constituted the main adduct formed in solutions containing low-to-medium Au-to-HSA ratios. Evidence was also obtained for the formation of a covalent adduct in which a single Au(CN) moiety was bonded to Cys34 of the protein. AuPEt3Cl reacted to a much lower extent with HSA that had Cys34 modified by formation of a disulfide bond to added cysteine, than with unmodified HSA. This suggests that the extent of modification of the protein in vivo may have an important influence on the transport and bioavailability of gold antiarthritic drugs.

Antirheumatic Agents↗
PubMed1984

The effect of cyanide on the uptake of gold by red blood cells.

Cyanide markedly increased the rate of uptake of gold by red blood cells when incubated with sodium aurothiomalate, a polymeric gold complex. Thiocyanate had no significant effect on gold uptake. The effect of cyanide was demonstrated to be due to the conversion of aurothiomalate to the complexion, aurocyanide, which is rapidly taken up by red blood cells. At a low ratio (1:20) of cyanide to aurothiomalate, cyanide appeared to act as a shuttle to carry gold into red blood cells. Tobacco smoking is known to increase the concentrations of gold in red blood cells in patients treated with aurothiomalate. The present data indicate that this effect of smoking is most likely due to cyanide inhaled in tobacco smoke and not to thiocyanate, a circulating metabolite of cyanide. An effect of cyanide on the uptake of polymeric gold complexes to target cells such as polymorphonuclear leukocytes and monocytes is suggested.

Aurothioglucose↗
PubMed1992

In vivo corrosion behavior of gold-plated versus titanium dental retention pins.

Two types of titanium dental retention pins and a gold-plated stainless steel pin were tested for their in vivo corrosion behavior. Six paired samples of titanium and gold-plated pins were placed in box preparations of 12 periodontally involved premolars. Half of the samples were restored with a high copper admixed type amalgam while the rest were restored with a BisGMA-POCl2 bonding resin and a hybrid visible light-cured composite resin. After 3 months in vivo, the teeth were extracted, and the pins were removed and examined with an electron microprobe. The surface of the titanium pins was found to be smooth and without defects. Only traces of Ca and P could be identified from dentin. The gold-plated pins demonstrated cracks and pores, especially at the outer part of the serrations, resulting in disruption of the electroplated film. Traces of Hg, Sn, Cu, S, Zn, Ca, K, Cl, P, and S were detected at the gold-plated pin/amalgam interface, while Cl and P were found at the gold-plated pin/composite resin interface. The in vivo corrosion resistance of the titanium pins was found to be superior to that of the gold-plated stainless steel pins.

Calcium↗
PubMed2004

Resonance light scattering spectroscopy study of interaction between gold colloid and thiamazole and its analytical application.

In this paper, we used resonance light scattering (RLS) spectroscopy to study the interaction between thiol-containing pharmaceutical-thiamazole and gold colloid. At pH 5.2, the resonance light scattering spectrum of gold nanoparticles has a maximum peak at 555 nm and the RLS intensity is enhanced by trace amount of thiamazole due to the interaction between thiamazole and gold colloid. The binding of colloidal gold to thiamazole results in ligand-induced aggregation of colloidal gold, which was characterized by RLS spectrum, ultraviolet-visible (UV-Vis) spectrum, and transmission electron microscopy (TEM). Based upon the study, we proposed a highly sensitive, gold colloid-based assay using RLS spectrum to detect pharmaceuticals for the first time. The mechanism of binding interaction between Au colloid and thiamazole was also discussed.

Absorption↗
PubMed1980

The gold rush 1925-35.

Although from the time of Koch onwards there had been desultory experiments with a variety of gold preparations in the management of pulmonary tuberculosis, gold as a recognised and accepted treatment did not emerge until 1925. In that year Holger Mollgaard of Copenhagen introduced sanocrysin, a double thiosulphate of gold and sodium, with which he had conducted an extensive series of animal experiments. The results of these were considered to justify its use in clinical practice and two physicians, Secher and Faber, undeterred by its toxicity, reported enthusiastically in its favour. Other Danish physicians followed but, alarmed by violent reactions, modified the dosage, an example followed by British workers. Encouraging results continued to be reported although each series contained a significant proportion of failures, and toxicity remained high. The first properly planned and fully controlled clinical trial took place in the United States and produced a report which was wholly adverse and which sounded the death knell of gold therapy throughout America. Until 1934-35 gold was used extensively in Europe but thereafter there was a sudden and largely universal cessation of interest and within a few years gold, introduced with such éclat and carrying so many high hopes, had vanished from the therapy of tuberculosis even though, at that point, no better alternative was available.

Animals↗
PubMed1991

Protein AG-gold complex: an alternative probe in immunocytochemistry.

The purpose of this study was to evaluate the use of protein AG tagged with colloidal gold as a reliable immunocytochemical reagent. Protein AG is a recombinant of 47.3 KD molecular weight and pI = 4.3, which displays immunoglobulin Fc binding sites for both staphylococcal protein A and streptococcal protein G. It adsorbs to 10-nm colloidal gold particles with a lower affinity than does protein A, and is saturable. A maximal number of 12 protein AG molecules could be accommodated on the gold particle surface. Protein AG-gold conjugates yielded positive signals in post-embedding immunocytochemical assays when used as a secondary reagent in conjunction with several species and classes of polyclonal (rabbit, goat, sheep, guinea pig) and mouse monoclonal immunoglobulins (IgG1, IgG2, and IgG3). In addition, protein AG-gold was found to be a useful reagent in immunoblot analysis because of its ability to bind and identify nitrocellulose-immobilized IgGs (rabbit, mouse, goat, sheep, rat, and cow). Its spectrum of specificity towards various types of antibodies combines those of the parental protein A and protein G molecules. The protein AG-gold complex therefore appears to be a highly versatile and convenient alternative probe for immunochemical and immunocytochemical studies.

Bacterial Proteins↗