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PubMed1983

Immunosuppressive actions of gold salts.

In rheumatoid arthritis both lymphocyte-mediated and antibody-mediated immune reactions are important for the inflammatory lesions. In vivo activated B lymphocytes/plasma cells, T lymphocytes and monocytes/macrophages (Mo) are intimately involved in the disease process. Several clinical observations suggest an immunosuppressive action of gold salts. In humans, gold salts interfere with a number of Mo functions in vitro, including cellular interactions between Mo and T lymphocytes. Some workers have shown that the activation of human T lymphocytes is inhibited by gold salts, most probably secondary to an inhibition of Mo-T cell cooperation. Recent experiments indicate that gold salts also affect the in vitro differentiation of human B lymphocytes in response to polyclonal activators. Both the gold atom and the SH group seem to be important for the immunosuppressive actions of gold salts.

Anti-Inflammatory Agents↗

PubMed1989

Inhibition of several enzymes by gold compounds. II. beta-Glucuronidase, acid phosphatase and L-malate dehydrogenase by sodium thiomalatoraurate (I), sodium thiosulfatoaurate (I) and thioglucosoaurate (I).

Bovine liver beta-D-glucuronide glucuronohydrolase, EC 3.2.1.32), wheat germ acid phosphatase (orthophosphoric monoesterphosphohydrolase, EC 3.1.3.2) and bovine liver L-malate dehydrogenase (L-malate: NAD oxidoreductase, EC 1.1.1.37) were inhibited by a series of gold (I) complexes that have been used as anti-inflammatory drugs. Both sodium thiosulfatoaurate (I) (Na AuTs) and sodium thiomalatoraurate (NaAuTM) effectively inhibited all three enzymes, while thioglucosoaurate (I) (AuTG) only inhibited L-malate dehydrogenase. The equilibrium constants (K1) ranged from nearly 4000 microM for the NaAuTM-beta-glucuronidase interaction to 24 microM for the NaAuTS-beta-glucuronidase interaction. The rate of covalent bond formation (kp) ranged from 0.00032 min-1 for NaAuTM-beta-glucuronidase formation to 1.7 min-1 for AuTG-L-malate dehydrogenase formation. The equilibrium data shows that the gold (I) drugs bind by several orders lower than the gold (III) compounds, suggesting a significantly stronger interaction between the more highly charged gold ion and the enzyme. Yet the rate of covalent bond formation depends as much on the structure of the active site as upon the lability of the gold-ligand bond. It was also observed that the more effective the gold inhibition the more toxic the compound.

Acid Phosphatase↗

PubMed1986

Chrysiasis: the role of sun exposure in dermal hyperpigmentation secondary to gold therapy.

To investigate the role of sun exposure in the pathophysiology of chrysiasis, we studied 10 Caucasian female patients with rheumatoid arthritis: 4 with clinically apparent chrysiasis and 6 without apparent pigmentation. Three patients without chrysiasis had received over 4 g of gold and 3 less than one g. The mean melanin score, determined by histological examination of sun exposed and nonsun exposed skin, was significantly higher in the sun exposed skin of the chrysiasis and high dose controls than low dose controls (p less than .05). Concentration of gold measured semiquantitatively by transmission electron microscopy and quantitatively by atomic absorption showed increased gold concentration in sun exposed when compared to nonsun exposed skin of chrysiasis and high dose controls (p = .26). Low dose controls had no gold demonstrated by either method. Our results suggest that gold deposition in the dermis stimulates melain production and that melanin is important in hyperpigmentation of chrysiasis. Furthermore ultraviolet light may induce preferential uptake of gold by the skin.

Arthritis, Rheumatoid↗

PubMedDate not supplied

Anterior-pituitary adrenal function of gold-treated patients with juvenile rheumatoid arthritis.

The hypothesis that gold therapy enhances endogenous cortisol secretion was tested in juvenile rheumatoid arthritis patients. The secretion of cortisol, dehydroepiandrosterone-sulfate (DHEA-S) and several peptide hormones was determined from plasma samples collected every 20 min for 24 hours. In random patients cortisol secretion was significantly greater in gold treated patients than in similar patients not receiving gold. However, when untreated patients were restudied after initiation of gold therapy, there was no significant change in cortisol secretion. Gold therapy also did not significantly alter secretion of the peptide hormones or DHEA-S. Thus, gold does not appear to influence endogenous hormone secretion.

Adolescent↗

PubMedDate not supplied

The comparative evaluation of the physical and chemical properties of gold compounds.

A wide range of modern physical and chemical techniques can be used to evaluate the properties of gold compounds. These allow the identification of the design features which control their pharmacological activity: the oxidation state (formal charge) on the gold atom, number and types of atoms bonded to gold (coordinated ligands), the stereochemical arrangement of ligands around gold (coordination geometry), and specific targeting groups in the ligands. The polymeric, hydrophilic, gold thiolate compounds are contrasted with the monomeric, lipophilic triethylphosphine gold compound auranofin (AF). The dynamic ligand exchange reactions of the 2 classes of drugs differ markedly; however other reactions are possible, and may lead to some common intermediates in vivo. This conclusion is based on preliminary results using nuclear magnetic resonance spectroscopy, a technique which allows us to monitor reactions in intact cells.

Aurothioglucose↗

PubMed1975

Nephrotoxic effect of parenteral and intraarticular gold. Ultrastructure and electron microprobe examination of clinical and experimental material.

The presence of gold in the kidney of a 58-year-old woman was confirmed by use of ultrastructural and microprobe examinations. A series of animal experiments were performed in which small single doses of gold were administered systemically and intraarticularly in rabbits. Both the colloidal suspension and the soluable salt gold sodium thiomalate (Myochrysine) were used. Selective lesions occurred in the proximal convoluted tubules and the mitochondria appeared to be the target organelle. They contained gold after gold sodium thiomalate but not after colloidal gold.

Animals↗

PubMed1993

Dicyanogold (I) is a common human metabolite of different gold drugs.

Gold based drugs and their metabolites have been characterized using reversed phase, ion pairing chromatography with an inductively coupled plasma mass spectrometer as an element specific detector. For a patient receiving gold sodium thiomalate the principal gold species in the urine is [Au(CN)2]-, which is also seen in a low molecular weight infiltrate of the blood. The same compound is also identified in the urine and blood of a patient taking auranofin and in patients taking solganol. This represents the first identification of a specific gold metabolite in biological fluids taken from patients undergoing gold therapy and the first evidence that different gold drugs have common metabolites.

Anions↗

PubMedDate not supplied

A review of the study of protein secretion applying the protein A-gold immunocytochemical approach.

Exocrine and endocrine types of secretion were investigated in various cells by applying the protein A-gold immunocytochemical approach. Several proteins secreted by rat pancreatic and parotid acinar cells, mouse ameloblasts, rat pancreatic B cells and lymph-node plasma cells, and frog hepatocytes were studied using specific antibodies. While light microscope immunohistochemistry has allowed for good topographical identification of positive cells in tissues, the protein A-gold approach used at the electron microscope level has demonstrated the presence of specific antigenic sites in particular cellular compartments. All secretory proteins studied were detected in the rough endoplasmic reticulum, the Golgi apparatus, and the secretory granules of the corresponding secreting cells. In addition, some of the proteins were also found in lysosome-like structures. When good ultrastructural preservation of the cellular organelles was achieved, the labeling was revealed with very high resolution and precise localization. In such cases, we found labeling over transitional elements of the endoplasmic reticulum and in smooth vesicles in the Golgi area. The Golgi apparatus was subdivided into three compartments according to differences in labeling: the cisternae on the cisside, those of the trans-side and the trans-most rigid one. Quantitative evaluations of the intensities of labeling have allowed for 1) demonstration of the high specificity of the different labelings; 2) revelation of the existence of a gradient of increasing intensity that follows precisely the progress of the proteins along their secretory pathway; and 3) identification of intracellular sites where increments of protein antigenicity occur. Furthermore, they have revealed the existence of alterations in protein processing that occurred under experimental and pathological conditions. Double-labeling approaches were performed to demonstrate two different antigenic sites on the same tissue section by applying protein A-gold complexes formed by gold particles of different sizes. Protein A-gold immunocytochemistry has also been combined with cytochemical and radioautographic techniques. This review thus demonstrates that high-resolution quantitative immunocytochemistry can contribute significantly to the investigation of the intracellular processing of secretory proteins. It also illustrates the potential and versatility of the protein A-gold technique, which in combination with other procedures constitutes a powerful method in cell biology.

Ameloblasts↗

PubMed1989

Thrombocytopenia associated with auranofin therapy: evidence for a gold-dependent immunologic mechanism.

Thrombocytopenia associated with gold therapy is thought to be due to an immune-mediated mechanism. Relatively few patients have been studied so far, and precise details of the pathophysiology of this disease remain undetermined. We report a patient with gold-induced thrombocytopenia resulting from auranofin therapy. The patient's plasma contained platelet-reactive antibodies detectable only in the presence of gold salts. Antibody binding occurred at gold concentrations ranging from 0.01 to 10,000 ng/ml. The binding occurred independently of gold salt used, suggesting that substitution of a different gold preparation in this patient would result in a similar thrombocytopenia. These data support a drug-dependent immune mechanism for platelet destruction.

Antibodies↗

PubMed1995

Distribution of colloidal gold tracer within rat parasternal lymph nodes after intrapleural injection.

BACKGROUND: Tracer studies are an important tool to obtain information about the processes involved in the immunological response. Colloidal gold is widely used as a tracer, but its small size of label can cause some difficulty during low-resolution analysis. To overcome this difficulty, we developed a new method to follow the route of tracer movement within lymph nodes. METHODS: We applied conventional X-ray analysis, X-ray fluorescence analysis (XFA) subtractional microscopy using synchrotron radiation (SR) beams, light microscopy, and ultrastructural analysis to study the distribution and quantity of colloidal gold coupled with albumin within rat parasternal lymph node 2, 4, 6, 8, and 10 h after intrapleural injection of the tracer. RESULTS: At all the time points XFA-SR revealed that tracer formed a circle with a maximum concentration in the node periphery. XFA-SR measured colloidal gold concentration in the nodes reached its maximum (0.5-0.75 weight %) in 6-8 h. Subtractional microscopy revealed superficially located groups of cells filled with colloidal gold tracer. Light microscopy and ultrastructural analysis confirmed that the tracer was concentrated in the reticular cells, situated in the sinuses of the node. Sinusoidal reticular cells concentrated tracer at much higher rates than sinusoidal macrophages. Four hours after injection, gold appeared in the lysosomes of the follicular reticular cells. At the same time point, evidence of antigen presentation was obtained. Antigen presentation proved to be an extremely rara event since only one ultrastructural incident was found in 150 analysed grids. CONCLUSIONS: SR is a valuable tool for the analysis of gold tracer passage within the living organism.

Animals↗

PubMed1982

Gold inhibition of the production of the second complement component by lymphokine-stimulated human monocytes.

The ability of gold sodium thiomalate to inhibit production of the second complement component (C2) by monocytes stimulated by a lymphokine (monocyte complement stimulator is demonstrated. This gold salt inhibits C2 production irreversibly if monocytes are incubated with it before or during lymphokine stimulation. Thiomalic acid is not inhibitory. Monocytes already stimulated by lymphokine are resistant to inhibition of C2 production by gold sodium thiomalate. Gold salts do not reduce monocyte viability, phagocytic ability (latex heads) accessory cell function (as measured by the ability to present antigen to autologous lymphocytes), or capacity to act as stimulating cells in mixed leukocyte culture. Gold sodium thiomalate's inhibition of monocyte responsiveness to lymphokine may be significant in explaining the therapeutic benefit of gold salts in rheumatoid arthritis.

Cell Survival↗

PubMed1985

Effects of gold sodium thiomalate on functional correlates of human monocyte maturation.

The mechanism of action of gold salts in the treatment of rheumatoid arthritis is unknown. Effects of gold on monocyte-macrophage function could be due to inhibition of maturation and differentiation. We found that 3 markers of monocyte differentiation, loss of peroxidase activity, spontaneous synthesis of C2, and spontaneous cytotoxicity for chicken erythrocytes, were all inhibited by gold treatment. This was not a general toxic effect since phorbol myristate acetate could still induce gold-treated monocytes to lyse chicken erythrocytes. Also, phorbol myristate acetate-stimulated superoxide production, a monocyte function not requiring further differentiation, was not inhibited by incubation with gold. Lymphokine-stimulated cytotoxicity for nucleated target cells, another function of monocytes, was inhibited only partially for certain target cells and not at all for others. These data suggest that gold has the capacity to selectively inhibit some monocyte functions which are associated with macrophage differentiation.

Cell Line↗

PubMed1993

Suppression of interleukin-2 and interleukin-2 receptor biosynthesis by gold compounds in in vitro activated human peripheral blood mononuclear cells.

OBJECTIVE: To further investigate the mechanism of action of gold compounds by studying their effects on interleukin-2 (IL-2) and IL-2 receptor (IL-2R) biosynthesis. METHODS: We cultured phytohemagglutinin- or anti-CD3 antibody-activated normal peripheral blood mononuclear cells (PBMC), as well as the erythroleukemic K562 cell line, in the presence of gold sodium thiomalate or auranofin. Tritiated thymidine incorporation assays, cytotoxicity assays, immunofluorescence analysis, enzyme-linked immunosorbent assay, Northern blot, and RNA dot-blot hybridization were used. RESULTS: Gold compounds, at concentrations attainable in vivo, inhibited the proliferation of normal PBMC, with no evidence of direct cytotoxicity. This inhibitory effect was associated with a dose-dependent suppression of both IL-2 and IL-2R messenger RNA accumulation. In contrast, the same concentrations of gold compounds failed to inhibit the spontaneous proliferation of the IL-2-independent K562 cells. CONCLUSION: Our findings suggest an IL-2/IL-2R-mediated mechanism for suppression of lymphocyte proliferation by gold compounds, which might account for the immunomodulatory effects of gold in patients with rheumatoid arthritis.

Antibodies↗

PubMedDate not supplied

Tartrate-resistant acid phosphatase: a potential target for therapeutic gold.

Gold compounds are disease-modifying agents for the treatment of rheumatoid arthritis. They act on the immune system but the mechanism is not fully understood. Gold has been shown to affect antigen processing by T-cells and also reduces expression of cytokines in macrophages. Tartrate-resistant acid phosphatase (TRAP), expressed by osteoclasts, macrophages and dendritic cells is an enzyme with roles in skeletal metabolism and the immune response. TRAP is able to degrade skeletal phosphoproteins including osteopontin, identical to the T-cell cytokine, Eta-1; we thus propose that TRAP regulates the Eta-1 pathway common to the immune system and skeleton. We compared the distribution of osteopontin and TRAP in sections of 18-day-old embryonic mice by immunohistochemistry. Both proteins occurred in the same locations. To determine whether gold compounds exert their effects by modification of TRAP activity, we examined the action of gold chloride and the prodrugs, aurothioglucose and aurothiomalate on the dephosphorylation of osteopontin by TRAP. Aurothioglucose and aurothiomalate had little effect on phosphatase activity; gold chloride was a potent non-competitive inhibitor (Ki < 47 x 10(-9) M). These findings indicate a possible molecular mechanism for the action of therapeutic gold and further implicate TRAP in the control of immunity.

Acid Phosphatase↗

PubMed2003

Gold coating and restenosis after primary stenting of ostial renal artery stenosis.

Predictors of restenosis after stent angioplasty of ostial renal artery stenosis (RAS) and long-term technical success, particularly the influence of gold coating, are unknown. During a 4-year period (1996-2000), we treated 156 consecutive patients with 219 ostial RAS of > or = 70% diameter stenosis. Gold-coated stents were used in 29% of RAS (n = 64); the vessel diameter ranged from 3 to 9 mm. The restenosis rate was 11.4% at 12 months, 12.2% for gold-coated stents and 11.1% for noncoated stents. Restenosis rates were 16% for < or = 4 mm, 17% for 5 mm, 10% for 6 mm, and 0% for > or = 7 mm (P < or = 0.05). In a backward stepwise logistic regression analysis including gold coating, vessel diameter, gender, diabetes, smoking status, as well as lesion diameter stenosis before and after stenting, vessel diameter was found the only independent predictor of restenosis (odds ratio = 0.57; 95% CI = 0.35-0.93; P = 0.02, for an increase in vessel diameter of 1 mm). Gold coating was not a significant predictor (odds ratio = 1.09; 95% CI = 0.39-3.03; P = 0.87). Seven major (4.5%) complications occurred. There were no procedural fatalities. The restenosis rate after stent angioplasty of ostial RAS is influenced by the vessel diameter but not by gold coating.

Adult↗

PubMed1984

Reproducibility and accuracy of left ventricular ejection fraction and wall motion determinations using gold-195m: a new ultrashort-lived radionuclide for cardiac studies.

Gold-195m has a halflife of 30.5 sec. Its ultrashort halflife and low radiation exposure (240 mrads to the kidney from a 20-mCi injection) make it an ideal agent for sequential first-transit studies of cardiac function. The reproducibility of ejection fraction and wall motion determinations were assessed from two gold-195m first-pass angiograms performed 3 min apart in 38 subjects. The accuracy of these evaluations was assessed by performing another first-transit study using technetium-99m. The correlation of the ejection fraction between the two gold-195m angiograms was 0.95 (standard error of the estimate (SEE) = 0.049) over an ejection fraction range of 20-78. The correlation of the ejection fraction using technetium-99m versus gold-195m was 0.95; SEE = 0.050. Only six minor discrepancies were noted when wall motion was evaluated in the gold-195m angiograms and compared with the technetium-99m study. We conclude that gold-195m can provide repeated, accurate, and reproducible ejection fraction and wall motion determinations with conventional imaging equipment at a substantially lower radiation exposure than with technetium-99m.

Angiography↗

PubMed1987

Wheat germ agglutinin-apoHRP gold: a new retrograde tracer for light- and electron-microscopic single- and double-label studies.

In this report, we describe a new colloidal-gold-labelled retrograde tracer, wheat germ agglutinin (WGA) conjugated to enzymatically inactive horseradish peroxidase (apoHRP). This protein gold complex (WGAapoHRP-Au) is a sensitive marker for retrograde tracing of the projections of CNS neurons at the light-microscopic (LM) level when a silver-enhancement procedure is used to detect the gold in the tracer. For electron-microscopic (EM) analysis, the silver-enhanced sections undergo a further gold-toning step. This protects against rapid oxidation and dissolution of the silver precipitate during the osmication procedure. A major advantage of WGAapoHRP-Au is that it can be used in a variety of multiple-labelling studies. When the retrograde transport of the new tracer is combined with that of the fluorescent dye, True Blue, neurons that have bifurcating axons can be readily demonstrated. Simultaneous immunofluorescent detection of the cytochemistry of the double-retrogradely labelled neurons is also possible. In contrast to a WGA-HRP gold complex, the new complex has no enzymatic activity. Thus HRP-based techniques (e.g., anterograde transport of WGA-HRP or peroxidase-antiperoxidase immunocytochemistry) can be performed on tissue that contains retrogradely labelled neurons marked with WGAapoHRP-Au without having to pretreat tissue so as to destroy endogenous HRP enzyme activity. At the EM level, the gold is readily distinguished from DAB immunoreaction product. This makes both LM and EM double-labelling studies possible. The great sensitivity of the new tracer, its compatibility with a variety of aldehyde fixatives, its ease of detection, and the fact that it can be simultaneously used with several fluorescent and HRP-based immunocytochemical and tracing techniques make WGAapoHRP-Au a valuable tool for LM and EM characterization of CNS cytochemistry and connectivity.

3,3'-Diaminobenzidine↗

PubMed2004

Fabrication, characterisation and voltammetric studies of gold amalgam nanoparticle modified electrodes.

The tabrication, characterisation, and electroanalytical application of gold and gold amalgam nanoparticles on glassy carbon electrodes is examined. Once the deposition parameters for gold nanoparticle electrodes were optimised, the analytical utility of the electrodes was examined in CrIII electroanalysis. It was found that gold nanoparticle modified (Au-NM) electrodes possess higher sensitivity than gold macroelectrodes. In addition, gold amalgam nanoparticle modified (AuHg-NM) electrodes were fabricated and characterised. The response of those electrodes was recorded in the presence of important environmental analytes (heavy metal cations). It was found AuHg-NM electrodes demonstrate a unique voltammetric behaviour and can be applied for electroanalysis when enhanced sensitivity is crucial.

Carbon↗