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PubMed1983

Gold therapy in the elderly rheumatoid arthritis patient.

Forty elderly (greater than or equal to 60 years old) and 101 young (less than 60 years old) rheumatoid arthritis patients receiving injectable gold therapy were followed prospectively between April 1971 and April 1982. The mean total gold compound received was 1,392 mg in the young group and 1,861 in the elderly group. Besides age, the only significant difference between the two groups was the increased gold compound received by the elderly. To determine efficacy and toxicity within and between certain age groups, the 141 patients were divided into 4 arbitrary age groups: group A (less than 30 years), group B (30-44 years), group C (45-59 years), and group D (greater than or equal to 60 years). The elderly responded to the gold therapy as well as the young patients did, at any time frame examined after 3 months of therapy. There was no difference in clinical benefit among groups A, B, C, and D. Nine patients in the elderly group and 15 in the young group had therapy discontinued because of no response. This difference was not significant among the groups A, B, C, and D. There was no difference in outcome of individual toxicity between the elderly and the young groups, and no difference in frequency of toxicity between the age groups A, B, C, and D. Serious hematologic toxicity occurred only in patients over 47 years of age, and nephrotic syndrome occurred only in patients over 52. In this study, gold therapy was found to be as clinically beneficial in the elderly as in the young patients, and the toxicity and drug failure rates were not significantly different.

Adolescent↗
PubMed2004

Immobilization and biocatalytic activity of fungal protease on gold nanoparticle-loaded zeolite microspheres.

Gold nanoparticles are excellent biocompatible surfaces for the immobilization of enzymes. However, separation of the gold nanoparticle-enzyme bioconjugate material from the reaction medium is often difficult. In this study, we investigate the assembly of the gold nanoparticles on the surface of the amine-functionalized zeolite microspheres in the formation of zeolite-gold nanoparticle "core-shell" structures and, thereafter, the use of this structure in immobilization of fungal protease. The assembly of gold nanoparticles on the zeolite surface occurs through the amine groups present in 3-aminopropyltrimethoxysilane (3-APTS). The fungal proteases bound to the massive "core-shell" structures were easily separated from the reaction medium by mild centrifugation and exhibited excellent reuse characteristics. The biocatalytic activity of fungal protease in the bioconjugate was marginally enhanced relative to the free enzyme in solution. The bioconjugate material also showed significantly enhanced pH and temperature stability and a shift in the optimum temperature of operation.

Adsorption↗
PubMed2007

Thermosensitive copolymer networks modify gold nanoparticles for nanocomposite entrapment.

The core-shell gold nanoparticles and copolymer of N-isopropylacrylamide (NIPAM) and N,N'-methylenebisacrylamide (MBAA) hybrids (Au@copolymer) were fabricated through surface-initiated atom-transfer radical polymerization (ATRP) on the surface of gold nanoparticles in 2-propanol/water mixed solvents. The surface of citrate-stabilized gold nanoparticles was first modified by a disulfide initiator for ATRP. The slight cross-linking polymerization between NIPAM and MBAA occurred on the gold surface and resulted in the formation of core-shell Au@copolymer nanostructures that were characterized by TEM, and FTIR and UV-visible spectroscopy. Such synthesized Au@copolymer hybrids possess clearly thermosensitive properties and exhibit "inspire" and "expire" water behavior in response to temperature changes in aqueous solution. Because of this property, we enable to trap and encapsulate smaller nanoparticles by using the free space of the copolymer-network scaffold anchored at the gold surface.

Gold↗
PubMed2003

A combined atomic force microscopy and molecular dynamics simulation study on a plastocyanin mutant chemisorbed on a gold surface.

A mutant of copper plastocyanin, covalently bound to an Au (111) surface through an engineered disulfide bridge, was investigated in aqueous medium by atomic force microscopy (AFM) and molecular dynamics (MD) simulations. Tapping-mode AFM images revealed adsorption of single molecules which are homogeneously distributed over the substrate and strongly bound to gold and display uniform lateral size. A statistical analysis of the height of the macromolecules on the gold substrate evidenced a distribution around a mean value consistent with that expected from the crystallographic data and with a relatively large standard deviation. A 10-ns classical MD simulation of mutated plastocyanin, hydrated by a layer of water, covalently bound to a gold surface by one or two sulfur atoms, was performed. The simulations indicate that the bound protein retains, in both cases, its overall tertiary structure during the dynamic evolution. Moreover, the macro-molecule can assume different orientations with respect to the gold substrate, which give rise to a distribution of heights on the gold substrate. Experimental and MD simulation results are compared and discussed in connection with the topological and dynamical properties of the protein system.

Adsorption↗
PubMed2004

Disposable twin gold electrodes for amperometric detection in capillary electrophoresis.

We describe a simple and easy way to construct gold microelectrodes for amperometric detection in capillary electrophoresis (CE). The gold microelectrodes, in single or twin sets, were obtained from recordable compact discs (gold-sputtered type), which present highly reproducible surface characteristics. The performance of these electrodes was evaluated by using a home-made CE equipment. The basic steps for the electrode construction are: drawing on a microcomputer; laser printing of the design on wax paper; heat-transfer of the toner onto the gold surface of a peeled recordable compact disc (CD-R); etching of the gold layer from unprinted regions; removal of the toner with a solvent; sealing of unused electrode areas with varnish. One electrode at a time was connected to a potentiostat (or two, to a bipotentiostat) and operated in a wall jet configuration relative to the CE capillary outlet. The amperometric signals were integrated for quantification purposes. Repetitive injections (n = 10) of a mixture containing iodide, ascorbic acid, dipyrone, and acetaminophen (20, 200, 500, and 100 microM), presented relative standard deviations of 2.9, 4.5, 6.1, and 4.0%, respectively. For these analytes, the detection limits (S/N = 3, 30 s of 100 mm hydrodynamic injection) were 0.1, 0.5, 3.1, and 1.1 microM, respectively.

Disposable Equipment↗
PubMed1980

Histocompatibility antigens and gold toxicity: a preliminary report.

To investigate the possibility that genetic factors are involved in the outcome of gold salt therapy for arthritis, histocompatibility antigens (HLA) were determined for 32 patients treated with gold salts. A comparison of patients who achieved remission following gold therapy with those who did not failed to demonstrate any difference in HLA antigens. Patients who had experienced adverse reactions during gold therapy were found to have an increased frequency of the HLA-B12 antigen. Gold toxicity occurred in 69.2 per cent (9/13) of patients with the B12 antigen, compared with 26.3 per cent (5/19) of patients without the antigen (P = 0.035).

Adult↗
PubMed2006

Immobilization and characterization of gamma-aminobutyric acid on gold surface.

gamma-Aminobutyric acid (GABA) is one of two main inhibitory neurotransmitters in the central nervous system that plays an important role in neuronal function and dysfunction. Immobilization of GABA molecules on a rigid surface in an ordered fashion will provide an opportunity to understand some of the fundamental properties related to its structure and function. In this study, we report a novel strategy for immobilization of bioactive GABA on gold substrate. GABA was immobilized in three consecutive steps, namely gold substrate amination, dextran covalent attachment, and GABA immobilization. Surface chemistry was verified at each step using XPS and FTIR. Bioactivity of GABA immobilized on the gold surface was studied using atomic force microscopy to reveal antigen-antibody binding. Nonspecific protein adsorption on the bioactive surface was analyzed quantitatively using anti-GABA antibody and an enzyme linked nonspecific anti-immunoglobulin-G antibody in an ELISA assay. GABA functionalized surface has high affinity for anti-GABA, while showing significantly low affinity for nonspecific anti-IgG antibody. All these data support the presence of a bio-functional immobilized GABA on the gold surface. In conclusion, we report a novel technique for immobilizing bioactive GABA molecules in an orderly fashion on gold substrates.

Coated Materials, Biocompatible↗
PubMed2006

Joint properties of cast Fe-Pt magnetic alloy laser welded to gold alloys.

This study investigated the joint properties of a cast Fe-Pt magnetic alloy (Fe-36 at % Pt) laser welded to three gold alloys. The gold alloys used were ADA Type II and Type IV gold alloys, and an Ag-based (Ag-Au) gold alloy. Cast plates (0.5 x 3.0 x 10 mm) were prepared for each alloy. After the cast Fe-Pt plates were heat treated, they were butted against each of the three alloys and then laser welded with Nd:YAG laser at 200 V. Homogeneously welded specimens were also prepared for each alloy. Tensile testing was conducted at a crosshead speed of 1 mm/min. Failure load (N) and elongation (%) were recorded. After tensile testing, the fractured surfaces were examined with the use of SEM. The failure-load values of the group of alloys welded homogeneously were ranked in the order of: Ag-Au alloy > Type IV alloy > Type II alloy > Fe-Pt alloy. The Type IV alloy welded to Fe-Pt alloy had the highest failure-load value among the three alloys tested. The elongation results tended to follow a similar pattern. The results of this study indicated that Type IV gold alloy is a suitable alloy for metal frameworks to which cast Fe-Pt magnetic alloy is laser welded.

Alloys↗
PubMed1988

Enzyme-gold affinity labelling of cellulose.

The enzyme-linked colloidal gold affinity labelling technique was tested as a method to localize cellulose on thin sections of plant cell walls and slime mold spores. Commercially available cellulase from cultures of Trichoderma reesei, the main components being cellobiohydrolase I and II (CBH I, CBH II) and endoglucanase (EG), was linked to colloidal gold by using standard techniques and applied as a dilute, buffered suspension to thin sections. After brief exposure, e.g., 15-30 minutes, cellulose exposed on the surface of sections was labelled with the enzyme-gold complex. Poststaining did not appear to have a deleterious effect on the labelled sections. The specificity of labelling was demonstrated by its complete inhibition when carboxymethylcellulose was incorporated in the labelling mixture, by lack of labelling of 1,4-beta-mannans or 1,3-beta-xylans in noncellulosic walls of marine algae, by lack of labelling of 1,4-beta-glucans in chitin, by much lower labelling density when done at 4 degrees C, and by lack of labelling when sections were predigested with cellulase. Labelling with the crude commercial cellulase was compared to labelling with purified CBH I-, CBH II-, and EG-linked colloidal gold, and the labelling pattern was similar. This method was found useful on conventionally fixed material and required no special preparation other than the use of inert (Ni or Au) grids and 0.5% gelatin to reduce nonspecific binding of the gold complex. Labelling was similar in the several embedding resins tested: LR White, Lowicryl K4M, Epon 812, and Spurr's.(ABSTRACT TRUNCATED AT 250 WORDS)

Affinity Labels↗
PubMed1989

Ultrastructural localization of DNA on ultrathin sections of resin-embedded tissues by the lactoferrin-gold complex.

Lactoferrin, a DNA-binding protein, was complexed to colloidal gold and applied on ultrathin sections of resin-embedded plant tissues and bacterial cultures. Optimal results were obtained when lactoferrin was tagged to colloidal gold particles at pH 9.2. Postfixation with osmium tetroxide and embedding with Epon did not prevent the accessibility of the protein towards its corresponding binding sites. In plant nuclei, labeling was observed over the dense chromatin and to a lesser extent over the dispersed chromatin. Nucleolar labeling was preferentially located over the dense fibrillar component. Gold particles were also found to be associated with chloroplasts and mitochondria. In prokaryotic cells, a dispersed labeling was noted over the cytoplasm and, in some cases, the aggregation of few gold particles suggested the presence of packed DNA fibrils. Various control experiments confirmed the specificity of the labeling pattern obtained. Lactoferrin-gold complex appears to be a valuable probe for the intracellular demonstration of DNA molecules in double-fixed and Epon-embedded tissues.

Colloids↗
PubMed1990

Small colloidal gold conjugated to Fab fragments or to immunoglobulin G as high-resolution labels for electron microscopy: a technical overview.

Fab-colloidal gold labelling in conjunction with negative staining and high-resolution electron microscopy was used for targeting single protein units in regular arrays. These were bacteriophage T4 polyheads with Fab-Au2.5, and a specific antibody binding site on the haemagglutinin polypeptide of influenza virus with Fab-Au3, Fab-Au2.5, and Fab-Au1-2. For the latter, IgG-Au3 was also used. Experimental details are summarized to provide generally applicable methods for the preparation of small gold colloids Fab-Au and of labelling. The putative mechanism of protein-gold complex formation and adsorption to preferred sites on Fab and IgG, most probably to sulphur-rich regions, is discussed. The influence of pH during complex formation was found to be of minor importance in the samples investigated. Reported experimental details and our own experiences suggest that the importance of a protein's pI relative to its optimum gold complexing pH critically depends on the nature of the protein in question rather than being of general importance for protein-gold complex stability.

Bacterial Proteins↗
PubMed2005

Synergistic enhancement of selective nanophotothermolysis with gold nanoclusters: potential for cancer therapy.

BACKGROUND AND OBJECTIVE: We developed a new approach that enhances selective photothermolysis of tumor through laser activation of synergistic phenomena around nanoclusters, which are self-assembled into cancer cells. STUDY DESIGN/MATERIALS AND METHODS: In vitro verification of this approach was performed by laser pulse irradiation (420-570 nm and 1064 nm; 8-12 nanosecond; 0.1-10 J/cm2) of MDA-MB-231 breast cancer cells targeted with primary antibodies to which 40-nm gold nanoparticles were selectively attached by means of secondary antibodies. Photothermal (PT) radiometry, thermolens techniques, electron microscopy, atomic force microscopy, silver and gold enhancing kits, and viability test (Annexin V-propidium iodide) were employed to study nanoparticle spatial organization, the dynamics of microbubble formation, and cell damage. RESULTS: The assembly of gold nanoclusters on the cell membrane was accompanied by increased local absorption and red-shifting as compared to cells that did not have nanoclusters. These effects were amplified by a silver-enhancing kit and pre-irradiation of cells with low laser-pulse energy. Finally, a significant increase in laser-induced bubble formation and cancer cell killing was observed using near-IR lasers (1064 nm). A cancer cell antigens was used to provide target specificity for nanoclusters formation making the cancer cells sensitive to laser activation. CONCLUSION: The described approach uses relatively small and simple gold nanoparticles offering more effective delivery to target. In addition, the further self-assembling of these nanoparticles into nanoclusters on live cells provides significant enhancement of laser-induced cell damage. These nanoclusters (gold "nanobombs") can be activated in cancer cells only by confining near-IR laser pulse energy within the critical mass of the nanoparticles in the nanoclusters.

Adenocarcinoma↗
PubMed1994

A general method for plasma membrane isolation by colloidal gold density shift.

A general method for isolating plasma membranes is described. Vegetative amoebae of Dictyostelium discoideum were allowed to directly adsorb raw colloidal gold of particle diameter 10-20 nm. After quenching the gold surface, the cells were lysed and the lysates were diluted in 60% sucrose and centrifuged through a 65% sucrose cushion to selectively pellet the gold-laden membranes. Three generally applicable exogenous cell surface markers were used to follow the plasma membranes: intercalated [3H]cholesterol, octadecylrhodamine, and the adsorbed gold colloid itself. The isolates routinely contained approximately 60% of these tags, enriched approximately 15-fold with respect to protein. The recovery and degree of enrichment of contaminating markers in the plasma membrane fraction were lysosomes (3% and 1-fold); mitochondria (11% and 3-fold); rough endoplasmic reticulum, as reflected by RNA (3% and 0.7-fold); and DNA (9% and 4-fold). Membrane proteins and lipids were quantitatively solubilized from the gold by detergents. We conclude that this methodology provides an approach to the isolation of plasma membranes which compares favorably to existing techniques with respect to yield, purity, and ease.

Cell Membrane↗
PubMed1998

Thyroid stimulating hormone assays based on the detection of gold conjugates by scanning force microscopy.

Low bulk concentrations of thyroid stimulating hormone (TSH) were detected by scanning force microscopy (SFM) using gold-labeled conjugates. Anti-TSH antibodies were covalently bound onto amino-modified silicon oxide wafers. Surface modification was examined by contact-angle measurements, ellipsometry, X-ray photoelectron spectroscopy, and SFM. Antibodies were found to form a monolayer of prone molecules with an average surface density of 5000 IgG/mum2. TSH molecules were then allowed to bind to immobilized antibodies. The immunological reaction was quantified by SFM using gold-labeled species. Two scanned force microscopic immunoassays (SFMIA) were compared: first, a competitive test which used gold-labeled TSH molecules mixed with free TSH antigens was performed . Afterward, a sandwich assay was carried out, using gold-labeled anti-TSH antibodies. This latter method was found to be far more sensitive than competitive SFMIA. Gold conjugates were also found to be of great use to quantify antigens in large volumes by a sandwich test: a sensitivity threshold as low as 0.015 ng of TSH/ml (0.075 UI/ml or 6 x 10(-13) M) was estimated.

Binding, Competitive↗
PubMed1998

Gold, the noble metal and the paradoxes of its toxicology.

Gold is possibly the most ancient and, in its recent incarnation as a delivery vehicle for gene therapy, one of the most modern agents in all of medicine's pharmacopoeia. Its administration to humans is both deliberate and inadvertent. It is universally recognized as the most inert of metals, yet it can be sensitizing. Gold's broadest clinical application (in rheumatoid arthritis) derives from a premise that was totally flawed. It is employed clinically to effect immune suppression yet it can engender toxicities that stem from immunostimulation. To complete this series of paradoxes, the toxicity of gold, unlike that of most pharmaceuticals, is, in general, not predictably related to the levels it attains within bodily tissues. Accordingly, the pharmacology and toxicology of gold is remarkably complex. Recent laboratory discoveries concerning gold's metabolism, have emphasized the important metabolic differences between its three oxidation states (0, I and III). When placed in the context of a wealth of clinical experience, these discoveries provide useful insights into its toxicology and shine a revealing light on the mechanisms which account for its seemingly paradoxical behaviour.

Animals↗
PubMed2004

Arsenic hazards to humans, plants, and animals from gold mining.

Arsenic sources to the biosphere associated with gold mining include waste soil and rocks, residual water from ore concentrations, roasting of some types of gold-containing ores to remove sulfur and sulfur oxides, and bacterially enhanced leaching. Arsenic concentrations near gold mining operations are elevated in abiotic materials and biota: maximum total arsenic concentrations measured were 560 microg/L in surface waters, 5.16 mg/L in sediment pore waters, 5.6 mg/kg DW in bird liver, 27 mg/kg DW in terrestrial grasses, 50 mg/kg DW in soils, 79 mg/kg DW in aquatic plants, 103 mg/kg DW in bird diets, 225 mg/kg DW in soft parts of bivalve molluscs, 324 mg/L in mine drainage waters, 625 mg/kg DW in aquatic insects, 7,700 mg/kg DW in sediments, and 21,000 mg/ kg DW in tailings. Single oral doses of arsenicals that were fatal to 50% of tested species ranged from 17 to 48 mg/kg BW in birds and from 2.5 to 33 mg/kg BW in mammals. Susceptible species of mammals were adversely affected at chronic doses of 1-10 mg As/kg BW or 50 mg As/kg diet. Sensitive aquatic species were damaged at water concentrations of 19-48 microg As/L, 120 mg As/kg diet, or tissue residues (in the case of freshwater fish) > 1.3 mg/kg fresh weight. Adverse effects to crops and vegetation were recorded at 3-28 mg of water-soluble As/L (equivalent to about 25-85 mg total As/kg soil) and at atmospheric concentrations > 3.9 microg As/m3. Gold miners had a number of arsenic-associated health problems, including excess mortality from cancer of the lung, stomach, and respiratory tract. Miners and schoolchildren in the vicinity of gold mining activities had elevated urine arsenic of 25.7 microg/L (range, 2.2-106.0 microg/L). Of the total population at this location, 20% showed elevated urine arsenic concentrations associated with future adverse health effects; arsenic-contaminated drinking water is the probable causative factor of elevated arsenic in their urine. Proposed arsenic criteria to protect human health and natural resources are listed and discussed. Many of these proposed criteria do not adequately protect sensitive species.

Animals↗
PubMed2004

Mercury hazards from gold mining to humans, plants, and animals.

Mercury contamination of the environment from historical and ongoing mining practices that rely on mercury amalgamation for gold extraction is widespread. Contamination was particularly severe in the immediate vicinity of gold extraction and refining operations; however, mercury, especially in the form of water-soluble methylmercury, may be transported to pristine areas by rainwater, water currents, deforestation, volatilization, and other vectors. Examples of gold mining-associated mercury pollution have been shown for Canada, the U.S., Africa, China, the Philippines, Siberia, and South America. In parts of Brazil, for example, mercury concentrations in all abiotic materials, plants, and animals, including endangered species of mammals and reptiles, collected near ongoing mercury amalgamation gold mining sites were far in excess of allowable mercury levels promulgated by regulatory agencies for the protection of human health and natural resources. Although health authorities in Brazil are unable to detect conclusive evidence of human mercury intoxication, the potential exists in the absence of mitigation for epidemic mercury poisoning of the mining population and environs. In the U.S., environmental mercury contamination is mostly from historical gold mining practices, and portions of Nevada remain sufficiently mercury contaminated to pose a hazard to reproduction of carnivorous fishes and fish-eating birds. Concentrations of total mercury lethal to sensitive representative natural resources range from 0.1 to 2.0 microg/L of medium for aquatic organisms; from 2,200 to 31,000 microg/kg BW (acute oral) and from 4,000 to 40,000 microg/kg (dietary) for birds; and from 100 to 500 microg/kg BW (daily dose) and from 1,000 to 5,000 microg/kg diet for mammals. Significant adverse sublethal effects were observed among selected aquatic species at water concentrations of 0.03-0.1 microg Hg/L. For some birds, adverse effects, mainly on reproduction, have been associated with total mercury concentrations (microg/kg FW) of 5,000 in feathers, 900 in eggs, and 50-100 in diet, and with daily intakes of 640 microg/kg BW. Sensitive nonhuman mammals showed significant adverse effects of mercury when daily intakes were 250 microg/kg BW, when dietary levels were 1,100 microg/kg, or when tissue concentrations exceeded 1,100 microg/kg. Proposed mercury criteria for protection of aquatic life range from 0.012 microg/L for freshwater life to 0.025 microg/L for marine life; for birds, less than 100 microg/kg diet FW; and for small mammals, less than 1,100 microg/kg FW diet. All these proposed criteria provide, at best, minimal protection.

Animals↗
PubMed1995

Localization of nuclear RNA by pre- and post-embedding in situ hybridization using different gold probes.

Pre-embedding and post-embedding in situ hybridization techniques were compared for the localization of RNAs in the nucleus. 28S rRNA and transcripts of the epidermal growth factor receptor (EGF-receptor) were localized with both hybridization methods. Pre-embedding hybridizations were performed on cells permeabilized with Triton X-100, whereas post-embedding hybridizations were carried out on Lowicryl K4M sections. From these studies it was concluded that, for labelling of 28S rRNA, the post-embedding in situ hybridization is preferred, whereas EGF-receptor transcripts were successfully detected only after pre-embedding in situ hybridization. Furthermore, the detection of the hybrids with ultra-small gold particles was compared to the detection with 6 nm gold particles in both pre- and post-embedding in situ hybridization studies. From our results it is concluded that the use of ultra-small gold particles results in higher label efficiency. Therefore, ultra-small gold particles are preferable to 6 nm gold particles for the detection of hybrids in high-resolution in situ hybridization experiments.

Cell Nucleus↗