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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Genetic and environmental interactions determine cancer risks but some cancer incidence is primarily a result of inherited genetic deficits alone. Most cancers have an occupational, viral, nutritional, behavioral or iatrogenic etiology. Cancer can sometimes be controlled through broad public health interventions including industrial hygiene and engineering controls. Chromium and nickel are two human carcinogens associated with industrial exposures where public health measures apparently work. Carcinogenic mechanisms of these metals are examined by electron-spin-resonance-spectroscopy and somatic-mutation-and-recombination in Drosophila melanogaster in this report. Both metals primarily affect initiation processes in cancer development suggesting important theoretical approaches to prevention and followup.
Mol Cell Biochem 2004 Jan
PMID:Genetic and cellular mechanisms in chromium and nickel carcinogenesis considering epidemiologic findings. 1497 59

A link exists between insulin resistance and many chronic disorders of aging including advancing-age. A safer means to prevent or, at least, slow the erosion of insulin sensitivity would provide a novel approach to better health. We compared the ability of a specific extract labeled fraction SX, as well as whole Maitake powder, fraction ES and fraction D of Maitake to influence SBP and various pertinent biochemical parameters when given orally to Zucker Fatty rats, a model of insulin resistance and type 2 diabetes mellitus. A secondary gain was the ability to ascertain the effects of bitter melon, olive oil, and sesame oil alone and combined with fraction SX to influence SBP. We found that a water-soluble fraction obtained from Maitake mushroom (SX) lowers SBP and fasting blood glucose significantly over the three to six weeks of study. While whole Maitake fraction lowered SBP effectively, the effects on fasting blood sugar were not apparent under the conditions of study. In contrast to fraction SX and fraction D, developed primarily to enhance immunity and suppress tumor development and growth, has essentially no effect on SBP under the conditions examined. An ether soluble fraction designated ES lowers SBP significantly. Interestingly, olive oil, unlike sesame oil, also lowers SBP. Finally, bitter melon and a combination of SX plus bitter melon also lower SBP. We conclude that fraction SX of Maitake mushroom may be useful to treat insulin resistance alone or combined with other natural products such as bitter melon and niacin-bound chromium.
Res Commun Mol Pathol Pharmacol 2002
PMID:Effects of Maitake mushroom fractions on blood pressure of Zucker fatty rats. 1508 Apr 98

In this study, we have examined the role of caspase-3 in apoptosis of lymphocytes induced by the chromium(III) complexes viz. tris-(1,10-phenanthroline)chromium(III) chloride (Cr(III)-phen) and trans-diaqua[1,3-bis(salicylideneamino)propanechromium(III)] perchlorate (Cr(III)-salprn). Evidence for caspase-3 activation and poly(ADP-ribose) polymerase (PARP) cleavage in lymphocytes exposed to Cr(III) complexes is revealed through Western blotting analysis. Blocking the activity of caspase-3 with z-DEVD-fmk, prevents apoptosis as evidenced through [3H]-thymidine incorporation, DNA fragmentation assay and measurement of sub-G1 cells by flow cytometry. Pretreatment of lymphocytes with free radical scavengers completely attenuates the activity of caspase-3 suggesting that reactive oxygen species (ROS) are upstream activators of caspase-3. Preincubation of lymphocytes with PP2, a selective Src-family tyrosine kinase inhibitor, abolishes the activation of caspase-3 indicating that Src-family tyrosine kinases viz. p56lck, p59fyn and p53/56lyn are mediators of caspase-3 activation during Cr(III) exposure. Collectively, our findings support a plausible mechanism in which Cr(III) mediates ROS generation that precedes the up-regulation of p56lck, p59fyn and p53/56lyn which eventually activates caspase-3 to promote apoptotic cell death of lymphocytes. To our knowledge, this is the first report suggesting the importance of Src-family tyrosine kinases for the activation of caspase-3 in metal-induced apoptotic cell death.
Mol Cell Biochem 2004 Apr
PMID:Caspase-3: its potential involvement in Cr(III)-induced apoptosis of lymphocytes. 1512 6

Octahedrally-coordinated Cr(3+) possesses peculiar spectral features which made easy to identify it in minerals, even in minor amounts. Chromium has been studied in uvarovite and fuchsite by optical and EPR spectra. Optical, EPR, FT-infrared and EPMA studies have also let to determine the presence of Fe(3+) and Ti(3+) and fluid inclusions within uvarovite and fuchsite. Absorption and scattering effects on the optical spectra obtained for Cr-bearing samples, resulting from the presence of inclusions, are also discussed in this work.
Spectrochim Acta A Mol Biomol Spectrosc 2004 Aug
PMID:Spectroscopic study of chromium, iron, OH, fluid and mineral inclusions in uvarovite and fuchsite. 1524 14

With a view to monitoring the changes in coloration caused by the nuclear reaction 51V(n, beta)52Cr in solution of vanadyl sulphate and using it for neutron dosimetry, electronic absorption spectra of vanadyl sulphate solutions were investigated at different concentrations of chromate impurity in micromolar range. It was observed that the presence of chromate enhances the absorptivity over a wide wavelength range serving essentially as a colouring agent for vanadium matrix, presumably due to charge transfer process. The absorbance at 380 nm varied linearly over a wide concentration range. The limit of detection of chromate obtained is shown to be adequate for detecting neutron-induced chemical transmutation of vanadium to chromium under standard reactor conditions, when used with long path length cells. It was observed that the absorbance does not change on electron irradiation, suggesting that radiolytic effects due to beta decay, if any, do not interfere in the measurement of neutron-induced changes. In addition to its potential for neutron dosimetry, this is the first report of a simple and direct method of estimation of Cr in vanadium matrix at sub ppm level.
Spectrochim Acta A Mol Biomol Spectrosc 2004 Aug
PMID:51V(n, beta)52Cr reaction for neutron dosimetry: development and assessment of a spectrophotometric method for determination of Cr in vanadium at sub ppm level. 1524 26

Particulate hexavalent chromium [Cr(VI)] compounds are well-established human lung carcinogens. However, their carcinogenic mechanisms are poorly understood as most investigators have used soluble Cr(VI) compounds. Recent work from our laboratory has found that barium chromate (BC) is also cytotoxic and clastogenic. To understand how BC relates to existing data on other particulate Cr(VI) compounds, we compared its cytotoxicity and clastogenicity with lead chromate (LC), which has been used as a prototypical particulate Cr(VI) compound, in WTHBF-6 cells, a near-normal human lung cell line. We found that BC is a more potent cytotoxicant, inducing 67%, 12%, 3%, and 0% relative survival at concentrations of 0.1, 0.5, 1, and 5 microg/cm2, respectively, while LC induced 90%, 71%, 43%, and 15% survival at these same concentrations. We found that BC was also more clastogenic, damaging 22% and 49% of metaphase cells at 0.1 and 0.5 microg/cm2, and causing complete cell cycle arrest at 1 and 5 microg/cm2. By contrast, 0.1, 0.5, and 1.0 microg/cm2 LC damaged 10%, 27%, and 37% of metaphase cells, respectively, and complete cell cycle arrest was not observed until a concentration of 5 microg/cm2 was reached. We found that BC and LC both partially dissolved in complete medium in the presence of cells, producing similar extracellular concentrations. Both compounds were also comparable with respect to particle uptake and the amount of intracellular Cr ions. Considering previous reports showing that lead ions were inactive and that sodium chromate and LC have similar clastogenic potencies, these data suggest that BC genotoxicity may not be solely mediated by Cr ions, but also involve some clastogenic activity of barium ions.
Environ Mol Mutagen 2004
PMID:Comparison of two particulate hexavalent chromium compounds: Barium chromate is more genotoxic than lead chromate in human lung cells. 1527 19

Sso10a is a member of a group of DNA-binding proteins thought to be important in chromatin structure and regulation in the hyperthermophilic archaeon Sulfolobus solfataricus. We have determined the structure of Sso10a to 1.47A resolution directly with unlabelled native crystals by a novel approach using sulfur single-wavelength anomalous scattering (SAS) from a chromium X-ray source. The 95 amino acid residue protein contains a winged helix DNA-binding domain with an extended C-terminal alpha-helix that leads to dimerization by forming a two-stranded, antiparallel coiled-coil rod. The winged helix domains are at opposite ends of the extended coiled coil with two putative DNA-recognition helices separated by 55A and rotated by 83 degrees. Formation of stable dimers in solution is demonstrated by both analytical ultracentrifugation and differential scanning calorimetry. With a T0 of 109 degrees C, Sso10a is one of the most stable two-stranded coiled coils known. The coiled coil contains a rare aspartate residue (D69) in the normally hydrophobic d position of the heptad repeat, with two aspartate-lysine (d-g') interhelical ion pairs in the symmetrical dimer. Mutation of D69 to alanine resulted in an increase in thermal stability, indicating that destabilization resulting from the partially buried aspartate residue cannot be offset by ion pair formation. Possible DNA-binding interactions are discussed on the basis of comparisons to other winged helix proteins. The structure of Sso10a provides insight into the structures of the conserved domain represented by COG3432, a group of more than 20 hypothetical transcriptional regulators coded in the genomic sequences of both crenarchaeota and euryarchaeota.
J Mol Biol 2004 Jul 30
PMID:The hyperthermophile protein Sso10a is a dimer of winged helix DNA-binding domains linked by an antiparallel coiled coil rod. 1531 64

A simple and reproducible spectrophotometeric method for the assay of cefotaxime sodium, cefuroxime sodium, and ceftriaxone disodium with metol-chromium(VI) reagent has been developed. The procedure is based on direct oxidation of metol by potassium dichromate in presence of drug in acidic medium and subsequent formation of ternary complex. Beer's law is obeyed in the range 0.2-28 microg ml(-1) at lambdamax 520 nm. For more accurate analysis, Ringbom optimum concentration range is found to be 0.8-26.5 microg ml(-1). The molar absorptivity and Sandell sensitivity were calculated. Six replicate analysis of solutions containing seven different concentrations of the examined drugs were carried out and gave a mean correlation coefficient < or =0.9996; the factors of the regression line equation for the three cephalosporins were calculated. The proposed method was applied to the determination of the examined drugs in pharmaceutical formulations and the results demonstrated that the method is equally accurate, precise, and reproducible as the official methods.
Spectrochim Acta A Mol Biomol Spectrosc 2004 Oct
PMID:Spectrophotometric determination of certain cephalosporins in pure form and in pharmaceutical formulations. 1535 Sep 19

Although several aspects of the digestive physiology of the hippopotamidae-non-ruminating foregut fermenters-have been described, ingesta kinetics and passage characteristics of these species are not well understood. The most outstanding feature of the hippo digestive physiology reported so far is the very long mean ingesta retention times (MRTs) measured by Foose [Foose, T., 1982. Trophic strategies of ruminant versus nonruminant ungulates. PhD dissertation, University of Chicago, Chicago.]. Since those data had been investigated with animals without water access, we intended to measure MRT in hippos which were allowed to enter water pools during the night. MRT parameters as well as dry matter (DM) digestibility were determined in four common (Hippopotamus amphibius) and four pygmy hippos (Hexaprotodon liberiensis) on two different diets each using cobalt ethylendiamintetraacetate (Co-EDTA) as a fluid, chromium (Cr)-mordanted fibre (<2 mm) as a particle and acid detergent lignin (ADL) as an internal digestibility marker. Four of the animals additionally received cerium (Ce)-mordanted fibres (2-10 mm) as particle markers. Total MRTs for fluids and particles ranged between 20-35 and 48-106 h in the common and between 13-39 and 32-107 h in the pygmy hippos. The difference between fluid and particle retention was greater than usually reported in ruminants. Excretion patterns of the markers differed from those usually observed in ruminants but resembled those reported for macropods (kangaroos), indicating a plug-flow reactor-like physiology in the hippo forestomach (FRST). This finding complements other described similarities between the macropod and the hippo forestomach. The measurements of larger particle retention profiles suggest that in the hippo, larger particles might be excreted either faster or at the same rate as smaller particles, indicating a general difference between ruminants and hippos with respect to differential particle retention. The digestive physiology of hippos is characterised by a generally low food intake, long ingesta retention times and dry matter digestibilities lower than reported in ruminants. Moderate digestibilities in spite of long retention times might be the result of the generally high average ingesta particle size in hippos. The comparatively easy management of pygmy hippos, together with the significant correlations between food intake, MRT and digestibility in the pygmy hippos of this study, recommends this species for further studies on the interplay of these parameters in herbivore digestive physiology.
Comp Biochem Physiol A Mol Integr Physiol 2004 Dec
PMID:Intake, ingesta retention, particle size distribution and digestibility in the hippopotamidae. 1559 90

Chromium(VI) is a toxic and carcinogenic metal that causes the formation of DNA phosphate-based adducts. Cr-DNA adducts are genotoxic in human cells, although they do not block replication in vitro. Here, we report that induction of cytotoxicity in Cr(VI)-treated human colon cells and mouse embryonic fibroblasts requires the presence of all major mismatch repair (MMR) proteins. Cr-DNA adducts lost their ability to block replication of Cr-modified plasmids in human colon cells lacking MLH1 protein. The presence of functional mismatch repair caused induction of p53-independent apoptosis associated with activation of caspases 2 and 7. Processing of Cr-DNA damage by mismatch repair resulted in the extensive formation of gamma-H2AX foci in G(2) phase, indicating generation of double-stranded breaks as secondary toxic lesions. Induction of gamma-H2AX foci was observed at 6 to 12 h postexposure, which was followed by activation of apoptosis in the absence of significant G(2) arrest. Our results demonstrate that mismatch repair system triggers toxic responses to Cr-DNA backbone modifications through stress mechanisms that are significantly different from those for other forms of DNA damage. Selection for Cr(VI) resistant, MMR-deficient cells may explain the very high frequency of lung cancers with microsatellite instability among chromate workers.
Mol Cell Biol 2005 May
PMID:Mismatch repair proteins are activators of toxic responses to chromium-DNA damage. 1583 65


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