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PubMed1979

Metabolism and distribution of gold compounds.

The pharmacokinetics of gold in blood and urine are compared during intramuscular and oral chrysotherapy for rheumatoid arthritis. Blood gold levels are 3 to 10 fold higher with injectable aurothioglucose and gold sodium thiomalate (50 mg/week) than with oral auranofin (6 mg/day). But, the serum half-life of the parenteral compounds is significantly shorter (5.5 days) than the oral agent (14-21 days). The gold content of urine is nearly 10 times higher with the intramuscular compounds than with the oral drug. The excretory pathways and tissue distribution of gold during conventional intramuscular chrysotherapy are reviewed. Forty percent of a 50 mg injection of gold sodium thiomalate is excreted in 7 days, of which 70% is recovered in the urine. Highest gold concentrations are found in the reticuloendothelial system, adrenal glands and kidneys, while the bone marrow, liver, skin and bone contain the greatest quantities of gold.

Animals↗
PubMed1979

Gold compounds in rheumatoid arthritis: clinical-pharmacokinetic correlates.

Currently available techniques do not enable the clinician to identify which patients with rheumatoid arthritis will respond favorably to chrysotherapy or to predict which patients will develop gold-related complications. Gold concentrations are similar in blood, urine, feces, skin, hair and nails in gold-responders and non-responders, and in gold-toxic and non-toxic patients. However, gold toxicity is a function of dosage schedule; higher than conventional doses increase the prevalence and severity of adverse reactions. Preliminary observations suggest that the frequency of common side-effects (e.g. dermatitis, stomatitis, proteinuria) from oral gold (auranofin) is less than that incurred with intramuscular gold prepartions. The possible genetic predisposition to develop gold toxicity is under investigation.

Aging↗
PubMedDate not supplied

Electrogenerated chemiluminescence of luminol in neutral and alkaline aqueous solutions on a silver nanoparticle self-assembled gold electrode.

The electrochemiluminescence (ECL) behaviour of luminol on a silver nanoparticle self-assembled gold electrode in neutral and alkaline solutions was investigated using conventional cyclic voltammetry (CV). The silver nanoparticle self-assembled gold electrode exhibited excellent ECL properties for the luminol ECL system. In neutral solutions, four ECL peaks (ECL-1-ECL-4) were observed at 0.73, 1.15, -0.46 and -1.35 V (vs. SCE), respectively. The intensities of these peaks were enhanced significantly compared with those on a bulk gold electrode and a gold nanoparticle self-assembled gold electrode. It was found that ECL-1 and ECL-2 on a silver nanoparticle-modified electrode were about 1000 and 1770 times stronger than those on a bare Au electrode and were about 17 and 15 times stronger than those on a gold nanoparticle-modified electrode, respectively. In alkaline solutions, four ECL peaks were also observed that were much stronger than those in neutral solutions, and ECL-1 and ECL-2 were enhanced by about three orders and one order of magnitude compared with those on a bare Au electrode and on a gold nanoparticle self-assembled electrode, respectively. Moreover, the silver nanoparticle-modified electrode exhibited good stability and reproducibility for luminol ECL. These peaks were found to depend on a number of factors, including silver nanoparticles on the surface of the modified electrode, potential scan direction, scan rate, scan range, the presence of O2 or N2, pH values, the concentrations of NaBr and luminol, and buffer solutions. The emitter of the ECL was confirmed as 3-aminophthalate by analysing the CL spectra. The surface state of the silver nanoparticle self-assembled electrode was characterized by scanning electron microscopy (SEM) and the interface property of the electrode was studied by electrochemical impedance spectroscopy (EIS). A mechanism for the formation of these ECL peaks is proposed. The results demonstrate that luminol has excellent ECL properties, such as strong ECL intensity and good reproducibility on a silver nanoparticle-modified gold electrode, in both neutral and alkaline solutions, which is of great potential in analytical applications.

Air↗
PubMed2006

Sustained increased risk of adverse cardiac events over 5 years after implantation of gold-coated coronary stents.

OBJECTIVE: To study the 5-year outcome of patients treated with gold-coated stent placement. BACKGROUND: We have previously shown in the setting of a randomized trial that gold-coated stents are associated with worse mid-term outcome, mainly because of an increased risk of restenosis, compared to uncoated stents. The long-term outcome and, in particular, mortality risk after implantation of gold-coated stents are not known. METHODS: A total of 731 patients with symptoms or signs of ischemia received randomly either a gold-coated (n = 367) or an uncoated steel stent (n = 364) of identical design. Patients were clinically followed-up at 1 and 5 years. The primary endpoint of the study was the composite of major cardiac events (death, myocardial infarction, or target vessel revascularization (TVR)). The incidence of death was a secondary endpoint. RESULTS: Five-year follow-up was available in 97.5% of the patients. The composite of death, myocardial infarction, or TVR occurred in 51% of the patients treated with gold-coated stents and 40% of the patients treated with uncoated stents (P = 0.005). Of note, there was a marked increase in the absolute difference in mortality between patients in the gold-coated and uncoated stent groups, from 1.6% at 1 year to 4.9% after 5-year follow-up (P = 0.09). A multivariate analysis showed that gold-coated stent implantation was independently associated with 5-year mortality (hazard ratio, 1.46; 95% confidence interval, 1.02-2.09; P = 0.04). CONCLUSIONS: Gold-coated stents are associated with a sustained increased overall risk for major cardiac events, and notably, they may increase the long-term mortality risk.

Aged↗
PubMed1989

Hepatic metabolism of colloidal gold-low-density lipoprotein complexes in the rat: evidence for bulk excretion of lysosomal contents into bile.

Rats were treated with 17 alpha-ethinyl estradiol to induce high levels of low-density lipoprotein receptors in hepatocytes. When these rats were given intravenous injections of low-density lipoprotein-colloidal gold complexes, most of the gold (labeled with 195Au) appeared to be taken up by Kupffer cells, as were complexes of colloidal gold with albumin or polyvinylpyrrolidone. However, when these rats were also administered gadolinium chloride, which blocks Kupffer cell activity, most of the low-density lipoprotein-gold (but not gold complexed with albumin or polyvinylpyrrolidone) was taken up into hepatocytes by receptor-mediated endocytosis and concentrated in peribiliary lysosomes, as determined by electron microscopy. Colloidal gold taken up as a complex with low-density lipoprotein was excreted into the feces via the common bile duct at a maximal rate of about 5% daily, 4 to 12 days after injection. Thereafter, the rate of gold excretion fell off until reaching a plateau after 3 weeks. At this late time, most of the colloidal gold was shown by electron microscopy to be in Kupffer cells, whereas earlier (6 days after injection) it was contained mainly in older hepatocytic lysosomes, identified by lipofuscin granules. It is concluded that, in rats, hepatocytic lysosomes empty most of their contents into bile every week or two, apparently by exocytosis.

Animals↗
PubMed1987

The use of avidin-gold complex for light microscopic localization of lectin receptors.

In the present study, we have investigated the use of avidin-gold complex (AG) as a possible cytochemical marker for visualizing and identifying lectin receptors in deparaffinized tissue sections. Monodispersed gold sols of 15 nm average diameter were prepared by sodium citrate reduction. The AG complex was prepared with highly purified egg-white avidin (avidin-D). Deparaffinized sections of cat duodenum were labeled with five different biotinylated lectins, then were washed and stained for 1-2 h with AG. Intensification of the gold staining was achieved by a modification of the silver-enhancement method. For each lectin, the labeling properties of the avidin-gold-silver (AGS) were compared with those of the avidin-biotin-peroxidase (ABC) and the lectin-gold (LG) methods. We found the lectin binding pattern demonstrated by the AG method to be similar to that of the ABC. The AG localization of the carbohydrate residues is more precise, compared to the peroxidase reaction due to lack of diffusion of the gold marker. Labeling with AGS resulted in improved staining over the AG method, similar to the staining intensity of the ABC. In addition, the two-step AG method provided more intense staining than the direct one-step procedure of the lectin-gold labeling. In conclusion, the use of the AGS method for histochemical visualization of lectin receptors requires a simple two-step procedure which allows highly accurate localization of tissue glycoconjugates. It entails using only a single gold-ligand complex applicable to any biotinylated lectin regardless of its biochemical nature.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Study of RNA distribution in the nucleolar components of Ehrlich cell using RNase-gold method.

The RNA distribution in Ehrlich tumour cell nucleoli has been investigated using RNase-gold method. This technique has been applied to sections of cells prepared under various fixation and embedding conditions. As expected, the specificity and intensity of labelling by gold particles have varied according to the experimental conditions used. Interestingly, however, it has been noted that the localization of gold particles does also vary and in particular within the fibrillar centre. This observation underlines the interest of assaying the RNase-gold complex under various conditions. The gold particles were particularly concentrated over the granular component and to a lesser extent, in the dense fibrillar component. In the latter constituent, it has been noted that the gold markers were preferentially localized at the edge of the dense fibrils. Surprisingly, a few gold particles have also been detected in the fibrillar centres. The weak labelling has persisted even after pepsin or DNase extraction but has completely disappeared after RNase extraction. Further, an inhibition of rRNA synthesis by a treatment with actinomycin D has not produced a significant decrease of the number of gold particles present in the fibrillar centre. These results suggest that fibrillar centres contain a small amount of RNA which would not correspond to pre-rRNA.

Animals↗
PubMed1989

Prevention of non-specific interactions of gold-labeled reagents on tissue sections.

The protein A-gold technique is amongst the most useful labeling techniques available for light and electron microscopic immunolabeling. Some electron microscopic studies, however, have suggested that protein A-gold, and other protein-gold complexes as well, may bind non-specifically to certain tissue structures, particularly in skin, creating a specious pattern of labeling. We utilized the protein A-gold technique with antiserum to both involucrin and keratin under a variety of conditions to document the specificity of labeling. When the standard conditions were followed, the protein A-gold technique produces highly specific results. These conditions include: 1. the blocking of unreacted aldehyde groups by amination; 2. the blocking of non-specific binding sites on tissue sections by preincubation with inert proteins; and 3. the use of proper concentration of the protein A-gold complex. However, non-specific labeling could be produced if the three components of the standard protocol were omitted. In particular, the use of too concentrated protein A-gold lead to non-specific labeling. We report here also updated working protocols for antigen detection with protein A-gold on semithin Lowicryl K4M and paraffin sections which provide optimal staining results.

Animals↗
PubMed1985

Simplified purification and testing of colloidal gold probes.

A novel efficient method for purifying and testing colloidal gold probes has been developed. The method consists of concentrating colloidal gold particles conjugated to IgG or protein A in dialysis bags over silica gel and purifying them by gel chromatography on small columns of Sephacryl S-400. Fractions collected are tested by paper immunocytochemical models. Comparisons to gold probes purified by conventional ultracentrifugation documents that ultrastructural staining intensities and total yield of gold probes is the same, but that the chromatographically purified gold probes are less prone to aggregation or clumping. The method has been extensively used for preparing conjugates of 5, 10 or 15 nm gold particles with antirabbit immunoglobulins but has also been exploited for preparing streptavidin-gold conjugates, protein A-gold conjugates and antirabbit immunoglobulin-silver conjugates.

Animals↗
PubMed1985

Conjugates of colloidal gold with native and acetylated low density lipoproteins for ultrastructural investigations on receptor-mediated endocytosis by cultured human monocyte-derived macrophages.

The morphological aspects of the binding and internalization of low density lipoproteins (LDL) and acetylated low density lipoproteins (AcLDL) by cultured human monocyte-derived macrophages were investigated. For this purpose, LDL and AcLDL were conjugated to 20 nm colloidal gold particles. After incubation of the cells with the conjugated lipoproteins at 4 degrees C some LDL- or AcLDL-gold complexes were found to be attached to the cell surface, but without characteristic localization. However, after incubation of the cells at 8 degrees C with either LDL-gold or AcLDL-gold, lipoprotein-gold complexes were present in clusters on the plasma membrane, often in coated pits. Cells incubated at 37 degrees C for various time periods showed internalization of both LDL- and AcLDL-gold complexes via small coated and non-coated vesicles and processing of the complexes in smooth-walled endosomes. When the cells were pulse-chased with LDL- or AcLDL-gold for 30 min at 37 degrees C, the gold conjugates occurred in dense bodies, probably lysosomes. The results suggest that although native and modified LDL are reported to be metabolized differently by macrophages, the morphological aspects of the endocytosis of LDL and AcLDL by cultured human monocyte-derived macrophages are similar.

Cell Membrane↗
PubMed1994

Lateral movement of mast cell surface protein detected by gold-labeled anti-IgE and its relation with fodrin.

Rat mast cells were incubated with gold-conjugated concanavalin A and the movement of gold particles was observed using a polarization microscope. In resting cells, the movement of gold particles was very slow. When cells were stimulated with compound 48/80, the gold particles rapidly moved laterally, unrelated to granule extrusion. When sensitized mast cells were stimulated with gold-conjugated anti-IgE (anti-IgE-gold), patching of anti-IgE-gold was also observed. Immunofluorescence microscopy of rat mast cells stained with anti-fodrin antibody and rhodamine-phalloidin revealed that both fodrin and actin exist beneath the cell membrane forming a complicated network. After stimulation of the cells with anti-IgE-gold, the fodrin network was disrupted and thin fluorescence was observed homogeneously on the cell surface. By means of Western blotting, alpha-fodrin was detected in the membrane fraction of mast cells at the 240 kDa protein band. From the present study, it is suggested that disruption of the fodrin network may occur in association with the process leading to mast cell degranulation.

Animals↗
PubMedDate not supplied

Adverse reactions with oral and parenteral gold preparations.

Auranofin (triethylphosphine gold), an oral gold preparation, has recently been made available, and along with injectable gold preparations, is of therapeutic value for rheumatoid arthritis. Serious gold toxicity is uncommon, and drug-related deaths rare. Many potential adverse reactions are similar, including dermatitis, stomatitis, thrombocytopenia, leucopenia, and proteinuria, generally with increased incidence in the injectable gold-treated patients. Oral gold is associated with benign lower gastrointestinal side effects, including diarrhoea, loose stools and abdominal cramps that are often dose-related and resolve spontaneously. The incidence of severe reactions such as thrombocytopenia, aplastic anaemia and exfoliative dermatitis is lower with oral gold than injectable preparations, and contributes to a superior risk-benefit ratio. The treatment of gold toxicity depends on the type and extent of organ involvement.

Administration, Oral↗
PubMed1997

[Epicutaneous testing with gold salts. 2 multicenter studies of the German Contact Allergy Group].

Between 1992 and 1994 two multicentre studies were performed in order to determine the frequency of sensitization to gold salts. In the first study (1992-1993), 872 patients were tested with gold sodium thiosulfate (NTS) 0.25% in Vaseline (V), 0.5% V. and with potassium dicyanoaurate (KDC) 0.002% aqueous solution. 44 patients (5.1%) had a positive patch test reaction to gold salts: 40 (4.6%) to NTS 0.5% V., 20 (2.3%) to NTS 0.25% V. and 5 (0.6%) to KDC. A higher number of positive patch tests to gold salts was noted in patients also sensitized to another metal salt (8.5%) as compared to those who showed no other sensitivities (3.6%). In a second multicentre study (1993-1994), 135 patients with associated sensitization to metal salts or intolerance to costume [correction of custom] jewelry were tested with the same test series as in the first study and with gold sodium thiomalate (ATM) 0.25% V.17 patients (12.6%) had a positive patch test reaction to gold salts: 16 (11.8%) to NTS 0.5% V., 10 (7.4%) to NTS 0.25% V. and 5 (3.7%) to ATM. The clinical relevance of the patch test reactions was considered as being "probable" in 5 cases; 1 in the first and 4 in the second study. Considering these results, NTS 0.5% V. seems to be the most reliable allergen for detecting gold allergy. However, a high proportion of probably false-positive reactions may occur. Further studies are therefore needed to analyze if the high frequency of positive patch tests to NTS 0.5% V. are due to irritant reactions or to a weak sensitization to gold without clinical symptoms.

Adult↗
PubMed2005

Use of ICP and XAS to determine the enhancement of gold phytoextraction by Chilopsis linearis using thiocyanate as a complexing agent.

Under natural conditions gold has low solubility that reduces its bioavailability, a critical factor for phytoextraction. Researchers have found that phytoextraction can be improved by using synthetic chelating agents. Preliminary studies have shown that desert willow (Chilopsis linearis), a common inhabitant of the Chihuahuan Desert, is able to extract gold from a gold-enriched medium. The objective of the present study was to determine the ability of thiocyanate to enhance the gold-uptake capacity of C. linearis. Seedlings of this plant were exposed to the following hydroponics treatment: (1) 5 mg Au L(-1) (2.5x10(-5) mol L(-1)), (2) 5 mg Au L(-1) + 10(-5) mol L(-1) NH4SCN, (3) 5 mg Au L(-1) + 5x10(-5) mol L(-1) NH4SCN, and (4) 5 mg Au L(-1) + 10(-4) mol L(-1) NH4SCN. Each treatment had its respective control. After 2 weeks we determined the effect of the treatment on plant growth and gold content by inductively coupled plasma-optical emission spectroscopy (ICP-OES). No signs of shoot-growth inhibition were observed at any NH4SCN treatment level. The ICP-OES analysis showed that addition of 10(-4) mol L(-1) NH4SCN increased the concentration of gold by about 595, 396, and 467% in roots, stems, and leaves, respectively. X-ray absorption spectroscopy (XAS) studies showed that the oxidation state of gold was Au(0) and that gold nanoparticles were formed inside the plants.

Bignoniaceae↗
PubMed2005

Assessing contamination paths of the German adult population with gold and platinum. The German Environmental Survey 1998 (GerES III).

BACKGROUND: Even though increased environmental platinum levels were found since the introduction of automobile catalytic converters, little is known about the pathways of corporal uptake and the bioavailability of platinum in the general adult population. The aim of this study is to identify and quantify the main exposure pathways of gold and platinum in the general adult population. METHODS: The German Environmental Survey 1998 (GerES III) collected population-based data on the corporal gold and platinum burden from a large sample of 1080 persons, 18-69 years of age. Urinary metal concentration was analysed by SF-ICP-MS. Exposure data were assessed by standardized questionnaires. Data were log transformed and analysed using multiple linear regression analysis with respect to exposure variables. RESULTS: The R2 of the linear regression model of urinary gold and platinum (ng/l) burden is 0.349 and 0.235, respectively. In both models, the number of teeth with noble metal dental alloy restorations (NMDAR) is the most important exposure pathway. One versus no tooth with NMDAR is associated with an increase of 23.7% in urinary gold and 35.6% in platinum concentration. Chewing gum intensifies the release of gold and platinum from NMDAR: every additional day per week when gum is chewed is associated with an increased gold (5.6%) and platinum (6.9%) burden. Furthermore, elevated urinary gold and platinum concentrations were found for higher creatinine concentrations, more frequent coffee consumption and for people from the upper social class. Gold burden is also increased in people with arthritis. Platinum burden is also increased in people living in western or northern Germany. Traffic-related variables had no significant effect on platinum burden.

Adult↗
PubMed2004

In vitro comparative analysis of the fit of gold alloy or commercially pure titanium implant-supported prostheses before and after electroerosion.

STATEMENT OF PROBLEM: For implant-supported prostheses, passive fit is critical for the success of rehabilitation, especially when alternative materials are used. PURPOSE: The purpose of this study was to compare interfacial fit of implant-supported prostheses cast in titanium to those cast in gold alloy. MATERIAL AND METHODS: Five 3-unit fixed partial dentures were fabricated in gold alloy (Degudent U) as 1-piece castings, and 5 others were similarly cast in commercially pure titanium (Grade 1). The interfacial gaps between the prostheses and the abutments were evaluated with an optical microscope, before and after electroerosion. Readings were made with both screws tightened (10 N.cm torque), and with only 1 side tightened, so as to also evaluate the passive fit of the prostheses. Data were compared statistically by 2-way analysis of variance and the post hoc Tukey multiple range test (alpha=.05). RESULTS: Before electroerosion, the interfacial gaps for the 1-piece prostheses were significantly smaller (P<.001) in the gold alloy group when the screws were tightened (Au=12.6 +/- 3.0 microm, compared to Ti=30.1 +/- 6.4 microm). When the side opposite the tightened side was analyzed, there was no significant difference between the gold alloy and titanium groups (Au=69.2 +/- 24.9 microm and Ti=94.2 +/- 39.6 microm). The electroerosion procedure significantly (P<.001) reduced the gaps at the interfaces for both groups under all conditions. Comparison between groups after electroerosion did not present significant differences when the side opposite the tightened side was analyzed, but the gold alloy group showed better fit when the tightened side was analyzed (12.8 +/- 1.4 microm for gold alloy; 29.6 +/- 4.4 microm for titanium) and when both screws were tightened (5.4 +/- 2.3 microm for gold alloy; 16.1 +/- 5.5 microm for titanium). CONCLUSIONS: Cast titanium prostheses, despite showing larger interfacial gaps between the prosthesis and abutment than those obtained with gold alloy, had improved fit after being subjected to electroerosion.

Analysis of Variance↗
PubMed1979

Bis(L-cysteinato)gold(I): chemical characterization and identification in renal cortical cytoplasm.

L-Cysteinatogold(I) was prepared by the reaction of L-cysteine with KAuBr4 in acidic media and its solubility determined from pH 4 to 10. The solubility at pH 7.4 and 37 degrees C is 1 microM. In the presence of excess cysteine, the solubility increases because of formation of bis(L-cysteinato)gold(I). The equilibrium-constant for formation of the bis complex is 2.1 +/- 0.4 X 10(-3), which at pH 7.4 CORRESPONDs to an apparant formation constant of 4.4 X10(4). The formation of the bis adduct was confirmed by chromatographic separation of the products of the reaction between [35S]-L-cysteine and Na2AuTM. This complex elutes with Kav = 1.15 which allows it to be distinguished from other gold thiolates that might form in vivo. The bis(cysteinato)gold(I) complex is shown to be present in kidney cytosol isolated from rats given Na2AuTM in vivo. When additional cysteine is added to the cytosol in vitro, the peak at 1.15 is increased, but if glutathione is added, the low molecular weight gold elutes at Kav = 1.00, which is taken as evidence for the existence of bis(cysteinato)gold(I) in the cytosol preparation. The amount of gold present as bis(cysteinato)gold(I) after 4 different dose schedules has been measured and found to increase with the total cytosol gold concentration. L-Cysteinatogold(I) does not dissolve in the presence of bovine serum albumin to form an adduct.

Animals↗
PubMed1980

The binding of Gold(I) to metallothionein.

The binding of gold(I) to metallothionein, MT, has been unambiguously established by the reaction of Na2AuTM with purified horse kidney MT. Zinc was displaced more readily than cadmium although the latter could be displaced using large Au/Cd ratios. The metal exchange reactions were complete within 2 hr of mixing. Further evidence that such reactions might be physiologically significant were obtained by studying in vitro metal displacements in the liver cytol of in vivo metal treated rats: When Na2AuTM was added to the cytosol of rats administered CdCl2 in vivo, zinc, copper and cadmium were displaced in 2/1/1 ratios from the metallothionein fraction. The zinc and cadmium displacement provide direct evidence that the gold was binding to MT. Addition of Cd+2 to liver cytosol of gold-treated rats resulted in displacement of copper and zinc, but not gold, from the MT fractions. When liver MT is prepared from rats exposed to Au or Cd, the Cd/protein ratio increased during the preparation, but the Au/protein ratio decreased. The Mt-bound metals account for 95% of the cytosolic Cd but only 15%-30% of the cytosolic gold in these studies. Thus, the nonspecific binding of gold to MT in vivo should be considered as one aspect in its equilibration among protein binding sites, which include, inter alia, metallothionein. Gold was found to coelute with zinc and cadmium in the MT fraction of rat kidney cytosol, when both Cd and Na2AuTM were administered to the rats. The possible significance of gold binding to MT in the treatment of rheumatoid arthritis--chrysotherapy--is briefly discussed.

Animals↗