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At least 919 records · Page 51Linked to original sources
PubMed2004

Electrochemical gene detection by using adamantyl naphthalene diimide coupled with ferrocenyl-beta-cyclodextrin.

The adamantyl moieties of adamantylnaphthalene diimide (AND) can be incorporated into the cavity of ferrocenyl-beta-cyclodextrin even where they are bound to double stranded DNA by threading intercalation. When this ternary complex is formed on the DNA probe-immobilized electrode, electrochemical DNA detection is feasible: the electrode hybridized with target DNA gave rise to a current peak corresponding to the ferrocene oxidation upon treatment with AND and ferrocenyl-beta-cyclodextrin (Fc-beta-CD).

Adamantane↗
PubMed2002

Mobilisation and bioavailability of arsenic around mesothermal gold deposits in a semiarid environment, Otago, New Zealand.

Arsenopyrite (FeAsS) is the principal arsenic (As) mineral in mineralised mesothermal veins (typically 5,000 mg/kg As) in southeastern New Zealand. Groundwater in contact with arsenopyrite-bearing rocks has elevated As concentrations (up to 0.1 mg/l). The arsenopyrite decomposes slowly on oxidation in soils and historic mine workings in a cool semiarid climate. Dissolved As is predominantly As(III) in association with arsenopyrite, but this is rapidly oxidised over days to weeks to As(V) in the vadose zone. Oxidation is facilitated by particulate Fe and/or Mn oxyhydroxides, and by bacteria in surface waters. Evaporative concentration of dissolved As(V) in the vadose zone causes precipitation of scorodite (Fe(III)As(V)O4*2H2O). Adsorption of As(V) to Fe oxyhydroxides in soils and groundwater pathways lowers dissolved As concentrations. Soils over mineralised veins typically have <200 mg/kg As, as most As is removed in solution on geological time scales. Most plants on the mineralised rocks and soils do not take up As, although some inedible species can fix up to 18 mg/kg As. Hence, bioavailability of As(V) is low in this environment, despite the substantial As flux. Similar As mobility is seen in an active gold mine processing plant and tailings. Arsenopyrite dissolves more rapidly on agitation, and mine waters can have dissolved As >200 mg/l, predominantly as As(V). This dissolved As decreases in tailings waters to near 2 mg/l, mainly as As(III) when in contact with arsenopyrite. Weak oxidation of evaporatively dried tailings causes cementation with scorodite and iron oxyhydroxides, and scorodite precipitation exerts some control on dissolved As(V) concentrations. High dissolved As in mine waters is lowered by adsorption to iron oxyhydroxides, and waters discharged from the mine site have negligible dissolved As.

Arsenic↗
PubMed2006

Resistance determinants of a highly arsenic-resistant strain of Leptospirillum ferriphilum isolated from a commercial biooxidation tank.

Two sets of arsenic resistance genes were isolated from the highly arsenic-resistant Leptospirillum ferriphilum Fairview strain. One set is located on a transposon, TnLfArs, and is related to the previously identified TnAtcArs from Acidithiobacillus caldus isolated from the same arsenopyrite biooxidation tank as L. ferriphilum. TnLfArs conferred resistance to arsenite and arsenate and was transpositionally active in Escherichia coli. TnLfArs and TnAtcArs were sufficiently different for them not to have been transferred from one type of bacterium to the other in the biooxidation tank. The second set of arsenic resistance genes conferred very low levels of resistance in E. coli and appeared to be poorly expressed in both L. ferriphilum and E. coli.

Arsenates↗
PubMed2005

Preparation of gold nanoparticles modified with tetrathiafulvalene via direct sulfur bridge.

A new tetrathiafulvalene-modified gold colloid was prepared. The modification or coordination of 2-[4,5-ethylenedisulfanyl-1,3-dithiol-2-ylidene]-1,3-dithiole-4-thiolate to the surface of gold nanoparticles was characterized by UV-Vis and Raman spectra, and cyclic voltammograms. The most valuable point of the modified gold nanoparticles is their redox activities. The cyclic voltammogram of the tetrathiafulvalene-modified gold colloid on a Pt electrode showed two pair of redox peaks, at E1/2 = +0.67 V and at +0.87 V (vs. a saturated calomel electrode, in MeCN-0.1 M Bu4NClO4), corresponding to TTF/TTF*+ and TTF*+/TTF2+, respectively. A gold electrode modified with a self-assembled monolayer of the tetrathiafulvalene was also prepared and its cyclic voltammogram behaviors were in accordance with those of the nano-Au system. The E1/2 data are higher than those of the neutral mother precursor and the separation of E1/2(1) to E1/2(2) becomes very narrow. The data of E1/2 also revealed that electrochemical behavior of the no-spacer system (TTF-S-Au) are different from that of a spacer system (TTF-S-(CH2)n-Au).

Colloids↗
PubMed1998

Immunogenetic basis of environmental lung disease: lessons from the berylliosis model.

The role of genetic factors has been hypothesized in the pathogenesis of a number of chronic inflammatory lung diseases. The genes of the major histocompatibility complex (MHC) locus on human chromosome 6 have been identified as important determinants in diseases caused both by inorganic and organic compounds such as beryllium, gold, acid anhydrides, isocyanates and grass pollens. Since many environmental factors are the determinants of the immunopathogenesis of asthma, pulmonary granulomatous disorders, hypersensitivity pneumonitis and fibrotic lung disorders, an understanding of the interaction between environmental factors is crucial to epidemiology, prevention and treatment of these disorders. Berylliosis is an environmental chronic inflammatory disorder of the lung caused by inhalation of beryllium dusts. A human leukocyte antigen class II marker (HLA-DP Glu69) has been found to be strongly associated with the disease. In in vitro studies, the gene has been shown to play a direct role in the immunopathogenesis of the disease. In human studies, the gene has been shown to confer increased susceptibility to beryllium in exposed workers, thus suggesting that HLA gene markers may be used as epidemiological probes to identify population groups at higher risk of environmental lung diseases, to identify environmental levels of lung immunotoxicants that would be safe for the entire population and to prevent disease risk associated with occupation, manufactured products and the environment. Studies on the associations between human leukocyte antigens and chronic inflammatory lung disorders are reviewed in the context of the berylliosis model.

Animals↗
PubMed2003

An amperometric biosensor for glucose based on electrodeposited redox polymer/glucose oxidase film on a gold electrode.

In this paper, we described a glucose biosensor based on the co-electrodeposition of a poly(vinylimidazole) complex of [Os(bpy)2Cl](+/2+) (PVI-Os) and glucose oxidase (GOX) on a gold electrode surface. The one-step co-electrodeposition method provided a better control on the sensor construction, especially when it was applied to microsensor construction. The modified electrode exhibited the classical features of a kinetically fast redox couple bound to an electrode surface and the redox potential of the redox polymer/enzyme film was 0.14 V (vs. SCE). For a scan rate of up to 200 mV s(-1), the peak-to-peak potential separation was less than 25 mV. In the presence of glucose, a typical catalytic oxidation current was observed, which reached a plateau at 0.25 V (vs. SCE). Under the optimal experimental conditions, the steady-state electrooxidation current measured at 0.30 V (vs. SCE) was linear to the glucose concentration in the range of 0-30 mM. Successful attempts were made in blood sample analysis.

2,2'-Dipyridyl↗
PubMed2004

[Docetaxel and non-small cell lung cancer].

Docetaxel (Taxotere) is a taxoid used in various tumoral diseases. Its role in metastatic or locally advanced non small cell lung cancer treatment is undeniable. In pretreated patients with metastatic NSCLC, two recent phase III trials have shown an improvement of survival and quality of life for patients receiving docetaxel. In front line treatment, docetaxel administered alone every three weeks or in combination with a platine compound has became a gold standard treatment. Activity of the associations cisplatinium/docetaxel and carboplatin/docetaxel is similar to those reported with previous combinations containing a platine derivative. The weekly schedule of docetaxel and its combination with other well known active drugs in NSCLC such as gemcitabin or vinorelbin deserve further evaluations. Therapeutic options with docetaxel in adjuvant situation in resected NSCLC or in combination with radiation therapy in operable locally advanced NSCLC should be developed in the next future.

Antineoplastic Agents, Phytogenic↗
PubMed2002

Forty-five years of chemical discovery including a golden quarter-century.

Inorganic chemistry became a passion for me as a graduate student in the 1950s. It was exciting to be part of the renaissance of the discipline, and I am pleased to have contributed to its strength. Physical concepts applied to the understanding of the properties of transition metal compounds guided our work initially. In the 1970s, probably as a direct result of the world abandoning the gold standard, the chemistry of gold was awakened after a long sleep. Much of the chemistry covered in this review of our work relates to novel compounds of gold and the properties they display which have been uncovered during the last 25 years of the 20th century. Stable metal-metal bonded Au(II) and organometallic Au(III) compounds, bi- and trimetallic oxidative addition, phosphorescent species with microsecond lifetimes, gold chains resulting from aurophilic bonding stronger than H-bonding, and recently, gold binding to organic pi acids have intrigued my group and other gold chemists during this period.

Journal Article↗
PubMed1992

Effect of repeated administration of chelating agents on distribution, excretion, and renal toxicity of gold sodium thiomalate in rats.

The effects of the repeated administration of D-penicillamine, 2,3-dimercaptosuccinic acid, 2,3-dimercaptopropane sulphonate, and N-(2-mercapto-2-methylpropanoyl)-L-cysteine 24 h after gold sodium thiomalate (AuTM) injection on the distribution, excretion, and renal toxicity of gold in rats were investigated. Three i.p. injections of these chelating agents (1.2 mmol/kg) at 1, 3, and 5 days after AuTM injection (0.026 mmol/kg) removed gold from kidney and liver through urinary and fecal excretion, and protected against the renal damage induced by AuTM. These findings indicate that these compounds are useful antidotes for gold toxicity.

Animals↗
PubMed2000

In-line coupling capillary electrochromatography with amperometric detection for analysis of explosive compounds.

Amperometric detection at a bare gold electrode has been in-line coupled with capillary electrochromatography (CEC) for analysis of nitroaromatic and nitroamine explosives in contaminated soils and ground water. The CEC column packed with 3 microm C18 particles performed best using a mobile phase containing 70-80% methanol, 30 or 20% water, 5 mM sodium dodecyl sulfate (SDS) and 10mM 2-(N-morpholino)ethanesulfonic acid (MES). In contrast, the separation column packed with 1.5 km C18 particles exhibited the best separation when only 30% methanol was added to a mobile phase containing 70% water, 7 mM SDS, and 10 mM MES. The detection, based on electrochemical reduction of the explosives (-0.7 or -1 V vs. Ag/AgCl, depending upon the level of methanol in the mobile phase), was compatible with such mobile phases. The detection limits for 13 explosives ranged from 100 to 200 ppb, i.e., about twofold better than those obtained with electrokinetic chromatography (EKC)/amperometric detection. From an operational viewpoint, exhaustive column conditioning was a prerequisite and care should be taken to prevent bubble formation and current breakdown during the course of separation. The CEC column equipped with amperometric detection successfully measured explosives in ground water and extracts prepared from contaminated soils and the results obtained agreed well with those of the U.S. Environmental protection Agency (EPA) method.

Azocines↗
PubMed2002

Surface treatment agent for dental metals using a thiirane monomer and a phosphoric acid monomer.

To develop a new surface treatment agent which improves the bond strength of adhesive resin to both non-precious and precious metals, experimental treatment agents containing both an adhesive bonding promoter for precious metals and one for non-precious metals were prepared by dissolving epithioalkyl methacrylate (EP3MA or EP8MA) and 10-methacryloyloxydecyl dihydrogen phosphate (MDP) in acetone. The surfaces of dental metals were treated by the treatment agents and metal specimens were butt-jointed together with MMA-PMMA resins. After 2,000 thermal cyclings in water at temperatures of 4 and 60 degrees C, tensile bond strengths were measured. The effectiveness of surface treatments was evaluated by tensile bond strengths and microscopic failure mode analysis after the tensile test. The combined treatment of EP3MA-MDP or EP8MA-MDP was used effectively for non-precious metals as well as precious metals, and was shown to be extremely effective compared with the single treatment of EP3MA, EP8MA, or MDP.

Adhesiveness↗
PubMed1986

Relative potency of chemical carcinogens in rodents.

Extensive carcinogenesis data compiled by Gold et al. for 770 compounds tested in 2944 chronic bioassays in animals provided an opportunity to compare cancer rates across animal species for a wide variety of compounds administered by various routes of exposure. The comparisons in this paper are restricted to the most frequently tested species: rats, mice, and hamsters. When sufficient experimental data exist, Gold et al. provide estimates of the TD50 (the chronic dose rate expressed in mg/kg body weight/day which halves the actuarially adjusted percentage of tumor-free animals at the end of a standard lifetime experiment). Since the current practice generally is to base risk assessments upon the data set producing the highest cancer risk, the ratio of the minimum TD50's provides a measure of the relative potency between two species for each compound administered to animals by the same route. The geometric means of the ratios of minimum TD50's for rats:mice are 1/2.2 and 1/1.3 for diet and gavage, respectively. A mean ratio for rats: mice of 1/1.48 is obtained for compounds administered in the diet when the tumor site is the liver for both species. In general the minimum TD50 is lowest for the rat and highest for the hamster. Although limited data are available for inhalation studies, this route of administration resulted in the poorest agreement between rats and mice. In general, comparisons of minimum TD50's across the three rodent species are generally within a factor of 100 for a wide variety of compounds.

Administration, Inhalation↗