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At least 793 records · Page 44Linked to original sources
PubMed1987

Effect of thiamine on the excretion of subcutaneously injected lead in rats.

The effect of thiamine on the excretion of lead in feces was investigated using rats injected subcutaneously with lead acetate and thiamine pyrophosphate. The amount of lead excreted increased with the amounts of thiamine administered, while lead concentrations in blood, liver and femur also increased. The amount of lead excreted in feces decreased, however, with administration of oxythiamine and vanadium. These results suggest that excretion of lead in feces is enhanced by thiamine and that it promotes evacuation of lead from the body.

Animals↗
PubMed2001

Intravaginal toxicity studies of a gel-microemulsion formulation of spermicidal vanadocenes in rabbits.

Bis-cyclopentadienyl complexes of vanadium(IV) or vanadocenes are rapid and potent inhibitors of human sperm motility with potential as a new class of contraceptive agents. We investigated the toxicity potential of intravaginally administered gel-microemulsion formulation of two representative vanadocenes, vanadocene acetylacetonato monotriflate (VDACAC) and vanadocene dithiocarbamate (VDDTC), in the rabbit model. New Zealand White rabbits in subgroups of three were exposed intravaginally to a gel-microemulsion with and without 0.1 or 0.25% VDACAC and VDDTC for 10 consecutive days. The doses of vanadocenes used were nearly 500- to 1250-fold and 2000- to 5000-fold higher than their respective in vitro spermicidal EC50 values. Animals were euthanized on day 11 and vaginal tissues were evaluated for local toxicity by histopathology, cell proliferating activity by immunohistochemical detection of proliferating cell nuclear antigen (PCNA), and in situ apoptosis by the terminal deoxynucleotidyl transferase-mediated FITC-deoxyuridine triphosphate nick end-labeling (TUNEL) assay and confocal laser scanning microscopy (CLSM). Blood was analyzed for clinical chemistry profiles. Vanadium content in selected organs and body fluids was determined by atomic absorption spectroscopy. None of the rabbits given 0.1% VDACAC and VDDTC intravaginally developed epithelial ulceration, edema, leukocyte influx, or vascular congestion characteristic of inflammation. Only minimal to moderate irritation was observed at 0.25% VDACAC and VDDTC. A significant decrease in epithelial and stromal PCNA expression was observed in the 0.25% dose group. However, TUNEL assay and CLSM revealed no staining in the vaginal epithelium and only minimal nonspecific staining in the stroma. Repetitive intravaginal application of 0.1 or 0.25% VDACAC and VDDTC had no adverse effects on clinical chemistry profiles. Vanadium was not incorporated into rabbit tissues and body fluids at levels above 1 microg/g. Thus, intravaginal administration of VDACAC and VDDTC at concentrations nearly 500 and 2000 times higher than their respective in vitro spermicidal EC50 values did not induce marked vaginal irritation, mucosal toxicity, or systemic absorption of vanadium in the rabbit model. The lack of significant mucosal or systemic toxicity of intravaginal vanadocenes observed may have particular clinical utility as a new class of contraceptive agents.

Administration, Intravaginal↗
PubMed1975

Systematic identification of drugs of abuse I: spot tests.

More than 40 of the most commonly encountered street drugs were subjected to several spot tests. These tests were carried out in a special sequence leading to the construction of a flowsheet. Thus, with a limited number of simple tests, it is possible to identify tentatively or narrow down the drug. Since each drug investigated was subjected to all selected tests, whether such tests were developed for this type of compound or not, some unexpected and undocumented results were obtained.

Alkaloids↗
PubMed2005

Crystal field analysis of energy level structure of LiAlO2:V3+ and LiGaO2:V3+.

A detailed analysis of the energy level structure of tetrahedrally coordinated V(3+) ion in lithium aluminum oxide LiAlO(2) (gamma-phase) and lithium dioxogallate LiGaO(2) is performed using the exchange charge model of the crystal field theory. The parameters of the crystal field acting on the V(3+) optical electrons are calculated from crystal structure data assuming C(1) point symmetry of the [VO(4)](5-) impurity center in LiAlO(2) and LiGaO(2). Crystal field splitting of all five LS terms of the V(3+) ion ((3)F, (3)P, (1)S, (1)D, (1)G) is calculated. The energy levels obtained are compared with experimental absorption spectra and results of application of other crystal field models (the angular overlap model and Racah theory) to the considered crystals; though only one fitting parameter of the exchange charge model was used, a good agreement with experimental data on the ground and excited state absorption is demonstrated.

Aluminum Oxide↗
PubMed2002

Heterometal cubane-type MFe(3)S(4) clusters (M = Mo, V) trigonally symmetrized with hydrotris(pyrazolyl)borate(1-) and tris(pyrazolyl)methanesulfonate(1-) capping ligands.

A series of heterometal cubane-type clusters containing [VFe(3)S(4)](2+) and [MoFe(3)S(4)](3+,2+) cores has been prepared. Ligand substitution of [(DMF)(3)VFe(3)S(4)Cl(3)](-) affords [(Tpms)VFe(3)S(4)L(3)](2)(-) (L = Cl(-) (8), EtS(-) (9), p-MeC(6)H(4)S(-), p-MeC(6)H(4)O(-)). A new procedure for the preparation of molybdenum single cubanes is introduced by the reaction of recently reported [(Tp)MoS(S(4))](-) with FeCl(2)/NaSEt to afford [(Tp)MoFe(3)S(4)Cl(3)](-) (1, 75% yield). This procedure is more efficient that the existing multistep synthesis of single cubanes, which generally affords clusters of mirror symmetry. Also prepared were [(Tp)MoFe(3)S(4)L(3)](-) (L = EtS(-) (2), p-MeC(6)H(4)S(-)). Reduction of 1 with borohydride gives [(Tp)MoFe(3)S(4)Cl(3)](2-) (5, 67%). Owing to the nature of the heterometal ligand, all clusters have idealized trigonal symmetry, reflected in their (1)H NMR spectra. Trigonal structures are demonstrated by crystallography of (Bu(4)N)[1,2], (Bu(4)N)(2)[5] x MeCN, and (Me(4)N)(2)[8,9]. The availability of 1 and 5 allows the first comparison of structures and (57)Fe isomer shifts of [MoFe(3)S(4)](3+,2+) in a constant ligand environment. Small increases in most bond distances indicate that an antibonding electron is added in the reduction of 1. Collective synthetic and electrochemical results from this and other studies demonstrate the existence of the series of oxidation states [VFe(3)S(4)](3+,2+,1+) and [MoFe(3)S(4)](4+,3+,2+) whose relative stabilities within a given series are strongly ligand dependent. Isomer shifts indicate that the reduction of 1 largely affects the Fe(3) subcluster and are consistent with the formal descriptions [MoFe(3+)(2)Fe(2+)S(4)](3+) (1) and [MoFe(3+)Fe(2+)(2)S(4)](2+) (5). Reaction of 1 with excess Li(2)S in acetonitrile affords the double cubane [[(Tp)MoFe(3)S(4)Cl(2)](2)(mu(2)(-)S)](2)(-), whose sulfide-bridged structure is supported by two sequential reductions separated by 290 mV, in analogy with previously reported double cubanes of higher charge. Trigonally symmetric single cubanes eliminate isomers in the formation of double cubanes and other cluster structures, and may be of considerable value in the preparation of new types of M-Fe-S clusters. (Tpms = tris(pyrazolyl)methanesulfonate(1-); Tp = hydrotris(pyrazolyl)borate(1-).)

Boron Compounds↗
PubMed2001

[Calculation of spectroscopic parameters of Ho3+ in Ho:YVO4 crystal].

The intensity parameters omega lambda of Ho3+ in Ho:YVO4 crystal were calculated with J-O theory according to the absorption spectrum. Based on these omega lambda values, the oscillator strength of excited energy state, spontaneous radiation rate, branching ratio and integrated emission cross section were estimated. A discussion on potentiality of application in the infrared laser material is given.

Chemical Phenomena↗
PubMed1987

Hydrolysis of WR2721 by mouse liver cell fractions.

A study of the dephosphorylation of WR2721 by broken cell preparations of mouse liver revealed the presence of at least two distinctive activities. One activity was inactivated by heat treatment and was present in the nuclear and microsomal fractions. It had an optimum pH at 9 and was inhibited by sodium vanadate, EDTA, and phenylalanine. Further subcellular fractionation demonstrated the localization of this activity in plasma membrane. A second WR2721 hydrolysis activity was detected in the cytosol fraction (postmicrosomal supernatant), which changed little with pH over the range of 5 to 10; sodium vanadate did not inhibit it. The cytosolic activity in response to heat treatment was complicated since there was an initial decrease followed by an increase in catalytic activity as a function of time at 55 degrees C. Enzyme kinetic analysis of the plasma membrane-associated activity in the microsomal fraction was performed, and Km and Vmax values of 12.5 and 69.9 nmol/min/mg protein, respectively, were obtained.

Amifostine↗
PubMed1986

Methodological aspects of assessing atmospheric contamination with metal aerosols in the vicinity of thermal power complexes.

A study of metal aerosols content in waste steam-containing gases from a thermal power station operating on oil fuel revealed that the concentrations of V2O5, Al2O3, Fe2O3, MnO2 and Cr2O3 are not influenced by the operational mode, type of boiler, the mean ratios being 1 : 0, 3 : 0, 27 : 0, 2 : 0, 03 : 0 and 0.25 respectively. Comparing the metal content in oil fuel and waste gases showed that no more than 10% of the studied compounds are sorbed on the boiler walls, the remaining 90% being released into the atmosphere. It is suggested that V2O5 be determined as an integral indicator with the aim of rapid hygienic assessment of the extent of atmospheric contamination with metal aerosols. The presented results may be used in preventive and regular sanitary surveillance during thermal power plant designing, construction and reconstruction.

Aerosols↗
PubMed1994

Is vanadium of human nutritional importance yet?

The trace element vanadium has been studied by the nutrition community for four decades, yet has not achieved essential status for human beings. It is found in compounds at valences of 2, 3, 4, or 5, with the tetravalent and pentavalent forms being the most common. In human beings, pharmacologic amounts of vanadium (ie, 10 to 100 times normal intake) affect cholesterol and triglyceride metabolism, influence the shape of erythrocytes, and stimulate glucose oxidation and glycogen synthesis in the liver. Vanadium's primary mode of action is as a cofactor that enhances or inhibits enzymes. Recent evidence suggests that vanadium may be essential for higher animals. After their mothers had been fed carefully formulated vanadium-deficient diets, second-generation goat kids suffered skeletal damage and died within 3 days of parturition. Although ubiquitous in air, soil, water, and the food supply, vanadium is generally found in nanogram or microgram quantities, which makes it difficult to measure. Estimates for the American intake of vanadium (based on a food intake of 500 g dry weight) are 10 to 60 micrograms/day. Vanadium levels in diets from five regions of the United States range from 30.9 +/- 1.5 in the Southeast to 50.5 +/- 1.5 micrograms/kg dry weight in the West. Although vanadium is thought to be essential for goats, new data may soon support its essentiality in human beings.

Animals↗
PubMed2004

[Study on solid phase extraction and spectrophotometric determination of vanadium in environmental samples with 2-(2-quinolinylazo)-1,3-dihydroxidebenzene].

Based on the color reaction of 2-(2-quinolinylazo)-1,3-dihydroxidebenzene (QADHB) with vanadium (v) and the solid phase extraction of its colored complex with C18 cartridge, a new method for the determination of vanadium was studied. In the presence of CTMAB and citric acid-sodium hydroxide buffer solution (pH 3.5) medium. QADHB reacts with vanadium(II) to form a stable 2:1 complex. The colored complex was extracted by C18 cartridge and eluted the retained chelate from cartridge with ethanol (containing 2% of acetic acid), then can be determined by spectrophotometry at 552 nm. Beer's law is obeyed in range of 0-1.0 mg/l. This method can be applied to the determination of vanadium in environmental samples with good results.

Azo Compounds↗
PubMed1998

Specific S-nitrosothiol (thionitrite) quantification as solution nitrite after vanadium(III) reduction and ozone-chemiluminescent detection.

Increasing evidence suggests that S-nitrosothiols (thionitrites) might represent naturally occurring nitric oxide surrogates and function as intermediates in nitrogen monoxide metabolism. A facile, sensitive, and selective micromethod has been developed and validated for quantification of S-nitrosothiols as their mercury-displaceable nitrogen monoxide content. In this method, brief (5-min), room-temperature pretreatment of S-nitrosothiol with a molar excess of aqueous mercuric chloride was used to liberate into solution, quantitatively, the nitrogen monoxide moiety, which rapidly and quantitatively converted to its stable solution end-product, nitrite. Solution nitrite was reduced back to nitric oxide with vanadium(III), and the nitric oxide was detected by gas-phase chemiluminescence after reaction with ozone in a commercial nitric oxide analyzer. A linear relationship was observed between S-nitrosothiol-bound nitrogen monoxide and ozone-chemiluminescent detector response over a wide range (16.3-3500 pmol) of nitric oxide, as generated by reaction of vanadium(III) with either nitrite standard or mercury-treated S-nitrosothiol. Assay response was quantitatively identical for equivalent amounts of nitrite and S-nitrosothiol-bound nitrogen monoxide. The method displayed 96% selectivity for nitrite vs. nitrate and negligible (<2%) interference by nitrosated compounds bearing nitrogen monoxide moieties bound to either nitrogen or carbon. The lower limits of quantitative sensitivity and qualitative detection were below 50 and 20 pmol S-nitrosothiol-bound nitrogen monoxide-equivalents, respectively. The intraday and interday coefficients of variation did not exceed 8%. This technique has been applied to quantify structurally diverse natural and synthetic S-nitrosothiols with quantitative recovery from complex biological samples such as culture media and plasma at levels of nitrogen monoxide-equivalents undetectable by the popular Saville colorimetric method.

Humans↗
PubMed2005

New homoleptic organometallic derivatives of vanadium(III) and vanadium(IV): synthesis, characterization, and study of their electrochemical behaviour.

The arylation of [VCl3(thf)3] with LiR(Cl), where R(Cl) is a polychlorinated phenyl group [C6Cl5, 2,4,6-trichlorophenyl(tcp), or 2,6-dichlorophenyl (dcp)] gives four-coordinate, homoleptic organovanadium(III) derivatives with the formula [Li(thf)(4)][V(III)(R(Cl))(4)] (R(Cl) = C(6)Cl(5) (1), tcp (2), dcp (3)). The anion [V(III)(C6Cl5)4]- has an almost tetrahedral geometry, as observed in the solid-state structure of [NBu4][V(C6Cl5)4] (1') (X-ray diffraction). Compounds 1-3 are electrochemically related to the neutral organovanadium(IV) species [V(IV)(R(Cl))4] (R(Cl) = C6Cl5 (4), tcp (5), dcp (6)). The redox potentials of the V(IV)/V(III) semisystems in CH2Cl2 decrease with decreasing chlorination of the phenyl ring (E(1/2) = 0.84 (4/1), 0.42 (5/2), 0.25 V (6/3)). All the [V(IV)(R(Cl))4] derivatives involved in these redox couples could also be prepared and isolated by chemical methods. The arylation of [VCl(3)(thf)(3)] with LiC6F5 also gives a homoleptic organovanadium(III) compound, but with a different stoichiometry: [NBu4]2[V(III)(C6F5)5] (7). In this five-coordinate species, the C6F5 groups define a trigonal bipyramidal environment for the vanadium atom (X-ray diffraction). EPR spectra for the new organovanadium compounds 1-6 are also given and analysed in terms of an elongated tetrahedral structure with C(2v) local symmetry. It is suggested that the R(Cl) groups exert a protective effect towards the vanadium centre.

Journal Article↗
PubMed2000

Investigation of the transported heavy metal ions in xylem sap of cucumber plants by size exclusion chromatography and atomic absorption spectrometry.

An 'off-line' high performance liquid chromatography-graphite furnace atomic absorption spectrometry (HPLC-GF-AAS) method using a size exclusion chromatography (SEC) column was developed to investigate heavy metal ions in xylem sap samples of cucumber plants grown in hydroponics containing iron as Fe(III)-ethylenediaminetetraacetate (Fe(III) EDTA), Fe(III) citrate or FeCl3 and exposed to lead, nickel or vanadium contamination. The SEC chromatogram of the samples contained the peak of nitrate ions (in significant concentration approximately 1400 microg/ml) and some small, unidentified compounds with molecular weight lower than 700 Da. The results indicate that Cu and Mn--which were added to the hydroponics as nutrient elements--determined in the collected fractions during the chromatographic runs are transported in the xylem vessels together with small inorganic ions like nitrate ions. In case of nickel other low-molecular weight compounds eluting earlier than the nitrate ions may take part in its transport toward the shoots. Lead could not be detected in the above mentioned fractions. Determination of vanadium in the fractions was not expected since it could not be detected in the sap samples.

Chromatography, High Pressure Liquid↗
PubMed1996

Exposure, metabolism, and toxicity of rare earths and related compounds.

For the past three decades, most attention in heavy metal toxicology has been paid to cadmium, mercury, lead, chromium, nickel, vanadium, and tin because these metals widely polluted the environment. However, with the development of new materials in the last decade, the need for toxicological studies on those new materials has been increasing. A group of rare earths (RE) is a good example. Although some RE have been used for superconductors, plastic magnets, and ceramics, few toxicological data are available compared to other heavy metals described above. Because chemical properties of RE are very similar, it is plausible that their binding affinities to biomolecules, metabolism, and toxicity in the living system are also very similar. In this report, we present an overview of the metabolism and health hazards of RE and related compounds, including our recent studies.

Animals↗