Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The specific, precise detection of volatile metal chelates has been obtained by coupling the effluent from a gas chromatograph directly to the burner head of a commerical atomic absorption spectrometer (AAS). Quantitation of chromium in the nanogram range has been accomplished with a detection limit of 1.0 ng. The chelation-extraction-gas chromatographic separation procedure coupled with the selective detection by AAS gives a relatively interference-free system that has been used to quantitatively analyse for chromium in standard biological materials NBS SRM 1571 Orchard Leaves and SRM 1569 Brewers Yeast. Metal chelates of iron, copper and cobalt have also been detected by this system.
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PMID:Coupled gas chromatography-atomic absorption spectrometry. 32 71

When initial velocities are measured with yeast hexokinase at pH 7, 17 degrees, the inert coordination complex chromium-ATP is competitive vs. MgATP and noncompetitive with glucose, with a dissociation constant of 4-6 muM in either the presence or absence of glucose. These patterns confirm a random kinetic mechanism for this enzyme. With CrATP present, however, the reaction slows down over the first several minutes to a much slower rate, suggesting tighter binding of CrATP with time. When CrATP, MgATP, and D-lyxose are preincubated with the enzyme for 10 min and the reaction started by addition of excess glucose, the dissociation constand of CrATP in now 0.13 muM and the reaction is linear with time. When glucose, CrATP, and enzyme are incubated together and then placed on a Sephadex column, 1 mol each of CrATP and glucose per active center is tightly bound to the enzyme, thus providing a simple and precise method of determining the concentration of active sites. This tight complex, after denaturation with acid, releases 25% free glucose and 75% of a chromium complex containing both ADP and sugar-6-P. CrADP-glucose-6-P is also slowly released from the enzyme during incubation, so that CrATP is actually a very slow substrate. Binding of CrATP with the formation of CrADP-sugar-6-P complexes is also induced by mannose, fructose, glucosamine, 2,5-anhydro-D-glucitol, 2,5-anhydro-D-mannose, and 2,5-anhydro-D-mannitol, while glucose-6-P, 6-deoxyglucose, and lyxose also induce tight binding of CrATP. With excess enzyme, only 25% of CrATP is bound, and the rest does not inhibit the hexokinase reaction. Since bidentate Cr(NH3)4ATP and monodentate CrADP also display inhibition which is tighter with time, but since bidentate CrADP is a poor inhibitor, the actural substrates in the hexokinase reaction appear to be beta, gamma-bidentate MgATP and beta-monodentate MgADP. Tighter inhibition by Cr-8-BrATP than by CrATP suggests that ATP ASSUMES THE SYN CONFORMATION ON THE ENZYME. The substrate inhibition by MgATP induced by the presence of lyxose is shown to be competitive vs. glucose and partial, and, together with other data available, to suggest a kinetic mechanism that is random, but where (1) the rate constant for release of glucose from E-glucose is equal to Vmax, and that for release of glucose from central complexes is less than Vmas; (2) the majority of the reaction flux when both substrates are present at Km levels goes through the path with glucose adding before MgATP, but where at physiological levels the flux through the two paths is more equal. Contd.
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PMID:Use of chromium-adenosine triphosphate and lyxose to elucidate the kinetic mechanism and coordination state of the nucleotide substrate for yeast hexokinase. 108 14

An artificial knee joint made of a cobalt alloy (Cr 27-38%, Mo 5-7%, others 9%, Co balance) failed in an orthopaedic patient with severe tissue reaction. Samples of synovial fluid and blood were analyzed for cobalt, chromium and molybdenum concentration using graphite furnace atomic absorption spectrophotometry (GFAAS). NIST SRM 909 Human Serum containing 91.3 micrograms/L chromium was used as the Cr Standard. To obtain reliable values for cobalt and molybdenum, three different independent analytical methods were employed to analyze each sample: 1) dilution of the samples with Triton TX-100 solution, followed by GFAAS; 2) microwave decomposition of the samples, followed by GFAAS; 3) classic nitric-perchloric acid decomposition of the samples, followed by GFAAS. The two decomposition methods were used to control the accuracy of the dilution method. The results showed that the non-decomposition method gave comparable results to the decomposition techniques for analysis of synovial fluid and blood. The data revealed that the patient had elevated levels of Co, Cr and Mo in both synovial fluid and blood with the values being 2-3 orders of magnitude higher in the synovial fluid from the affected knee.
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PMID:Determination of chromium, cobalt and molybdenum in synovial fluid by GFAAS. 182 23

An isotope dilution gas chromatography/mass spectrometry method using lithium bis(trifluoroethyl)dithiocarbamate as a chelating agent is described for the determination of chromium in urine. A wet digestion procedure with HNO3-H2O2 is used for oxidizing the organic matter associated with urine samples. The isotope ratios are measured by selected ion monitoring in a general-purpose mass spectrometer using a 10-m fused silica capillary column. Memory effect, in sequential analyses of samples with different isotope ratios, was evaluated by preparing a series of synthetic mixtures and was found to be negligible. The accuracy of the method was verified by quantitation of chromium in the NIST freeze-dried urine reference material, SRM-2670, with a recommended chromium concentration of 13 micrograms/L in the normal level and certified chromium concentration of 85 +/- 6 micrograms/L in the elevated level.
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PMID:Determination of chromium in urine by stable isotope dilution gas chromatography/mass spectrometry using lithium bis(trifluoroethyl)dithiocarbamate as a chelating agent. 217 91

Development of a new method for the determination of Cr(III) and Cr(VI) is described. Anion-exchange high-performance liquid chromatography (HPLC) was used to separate Cr(III) and Cr(VI) with on-line detection by inductively coupled plasma atomic emission spectroscopy (ICP-AES) at 2766 A in preliminary studies, and inductively coupled plasma mass spectrometry (ICP-MS) with single-ion monitoring at m/z 52 and m/z 53 for final work. A mobile phase consisting of ammonium sulfate and ammonium hydroxide was used, and a simple chelation procedure with EDTA was followed to stabilize the Cr(III) species in standard solutions. ICP-MS results indicated the feasibility of using chromium isotope m/z 53 instead of the more abundant m/z 52 isotope due to a high mobile-phase background most significantly from the SO+ polyatomic interference. The absolute detection limits based on peak-height calculations were 40 pg for Cr(III) and 100 pg for Cr(VI) in aqueous media by HPLC-ICP-MS. The linear dynamic range extended from 5 ppb (ng/ml) to 1 ppm (micrograms/ml) for both species. By HPLC-ICP-AES, detection limits were 100 ng for Cr(III) and 200 ng for Cr(VI). Cr(III) was detected in NIST-SRM 1643c (National Institute of Standards and Technology-Standard Reference Material, Trace Elements in Water) by HPLC-ICP-MS at the 20 ppb level.
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PMID:Chromium speciation by anion-exchange high-performance liquid chromatography with both inductively coupled plasma atomic emission spectroscopic and inductively coupled plasma mass spectrometric detection. 758 51

The present study attempted to evaluate pentoxifylline's mechanism(s) of action in the prevention of acute renal failure by examining its vascular decongestant activity in a rat model for acute renal failure and inhibitory activity of nitric oxide release from activated macrophage-like (RAW 264.7 cells) and murine mammary adenocarcinoma (EMT-6 cells) cell lines. Radiolabeled chromium-erythrocytes were injected intravenously into all rats. Following occlusion of the left kidney for 45 minutes, rats were treated with pentoxifylline or normal saline. The medulla of the left (ischaemic) kidney had significantly higher radioactive counts than the right (control kidney) following an intravenous dose of normal saline. The medulla to whole blood radioactivity ratio of the left kidney was significantly greater than for the right (control) kidney. Animals administered intravenous pentoxifylline (5 mg/kg) had significantly lower radioactive counts in the medulla of the left (ischaemic) kidney than animals administered intravenous normal saline. No differences in radioactivity counts in the medulla of the left (ischaemic) kidney were observed when animals received intraperitoneal pentoxifylline (45 mg/kg) versus normal saline. In a second set of experiments the nitrite synthesis and percent cytotoxicity of pentoxifylline- and dexamethasone-treated cells were determined. Pentoxifylline at concentrations of 4 mM and 8 mM significantly decreased nitrite synthesis in RAW 264.7 cells, and at pentoxifylline concentrations of 2 mM, 4 mM, and 8 mM in EMT-6 cells compared to untreated cells. Dexamethasone at a concentration of 1 microM decreased nitrite synthesis in RAW 264.7 and EMT-6 cells compared to untreated cells. Pentoxifylline at concentrations of 0.5 mM through 8 mM significantly decreased cytotoxicity in RAW 264.7 and EMT-6 cells compared to untreated cells. Dexamethasone at a concentration of 1 microM decreased cytotoxicity in RAW 264.7 and EMT-6 cells compared to untreated cells. These finding suggest that pentoxifylline's ability to prevent acute renal failure may be a consequence of reduced vascular congestion and inhibition of nitric oxide release from activated macrophages.
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PMID:Nephroprotective mechanism(s) of pentoxifylline: reduction of erythrocyte-mediated vascular congestion and inhibition of nitric oxide release. 888 51

Most conventional digestion procedures, such as dry ashing and wet ashing, are tedious and labor intensive. Microwave digestion is a good alternative, because microwave dissolution is faster, safer, and simpler, and provides more controlled reproducible conditions than conventional methods. The purpose of this study was to develop a microwave digestion method for mineralizing meat and bone meal diets, feces, and ileal contents. Each sample was heated on a hot plate for 10 min, dry ashed at 65 degrees C for 4 h, and transferred into microwave vessels. Then, 10 mL 70% HNO3 was added. Samples were digested for 7, 10, and 20 min at 95, 90, and 85% power, respectively. After the heating cycle, 6 mL 30% H2O2 was added, and samples were returned to the microwave for a second heating cycle of 1 and 7 min at 95% and 90% power, respectively. Finally, chromium concentration was determined by flame atomic absorption spectrophotometry. The digestion method was validated by using a standard reference material, SRM domestic sludge 2781, with a certified chromium value of 195 +/- 9 micrograms/g. The value obtained in this study was 178 +/- 11 micrograms/g, for a difference of 17 micrograms/g. Spike recovery experiments resulted in 103.16 and 100.35% recoveries of chromium from diet and feces samples, respectively. Coefficients of variation were 10.8 and 7.8%, respectively.
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PMID:Use of microwave digestion and atomic absorption spectrophotometry to determine chromic oxide as a digestibility marker in feed, feces, and ileal content. 1036 75

The possible human health effects resulting from the ingestion of soil bound heavy metals can be poorly estimated if concentration of total metals in soil, rather than bioavailable fraction of metals, are incorporated into dose calculations. Information regarding bioavailability often is obtained from animal studies, which are not easily conducted and still may not represent human conditions. A rapid simulation of the bioaccessible fraction of contaminant in a soil, in which that fraction is mass soluble in gastrointestinal tract fluids, has been employed in an in vitro sequential extraction technique. Using a mass-balance analytical approach to measure bioaccessibility in four soils, the results indicated that each metal had a bioaccessible fraction less than its total metal content. Lead (Pb) in Standard Reference Material, Montana SRM 2710, was found to be 62 +/- 1% bioaccessible; Pb in contaminated soil collected from Bunker Hill, ID, USA was 70 +/- 11%. Lead in Jersey City, NJ, USA slag material was only 39 +/- 14% bioaccessible while Pb in a residential soil was 69%. Arsenic (As) and chromium (Cr) data from select soils also have bioaccessibility less than the corresponding total metal in soil, with 41 +/- 2% As in a residential soil, 66 +/- 8% As in SRM 2710, and 34 +/- 14% Cr in Jersey City slag material. Recovering the soil at the end of the in vitro extraction allowed for the determination of the insoluble fraction of total metal in soil. This recaptured soil metal mass was a valuable measurement since it greatly reduced analysis and therefore labor and time, yet also provided a reasonable estimate of bioaccessibility. It also allowed for calculation of a bioaccessibility value in a soil containing very low metal mass, which would otherwise have resulted in a non-detectable concentration at the dilutions required in the synthetic human biofluid system.
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PMID:The estimation of the bioaccessibility of heavy metals in soils using artificial biofluids by two novel methods: mass-balance and soil recapture. 1063 99

In the present work, a solid phase extraction system has been proposed for speciation of Cr(III) and Cr(VI) in the real samples. The procedure based on the adsorption of chromium(III) as dithizonate chelate on the Chromosorb 108 resin. After reduction of Cr(VI) by concentrated H2SO4 and ethanol, the system was applied to the total chromium. Cr(VI) was calculated as the difference between the total Cr content and the Cr(III) content. The influences of the analytical parameters including pH of the aqueous solution, amounts of dithizone, eluent type, sample volume and flow rates of the sample and eluent solution were investigated. No considerable interferences have been observed from other investigated anions and cations on the chromium speciation. The adsorption capacity of sorbent was 4.50 mg/g Cr(III). The detection limit of Cr(III) is 0.75 microg/L. The proposed method was applied to the speciation of chromium in environmental samples including natural waters and total chromium preconcentration in microwave digested Turkish tobacco, coffee and soil samples with satisfactory results. In order to verify the accuracy of the method, two certified reference materials (NIST SRM 1573a Tomato Leaves and RTC-CRM 025-050 Metals on Soil) were analyzed and the results obtained were in good agreement with the certified values. The relative errors and relative standard deviations were below 5% and 9%, respectively.
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PMID:Chromium speciation in environmental samples by solid phase extraction on Chromosorb 108. 1623 41

The sorption conditions including pH of the aqueous solution, sample volume, etc., on Celtek clay of copper(II), cadmium(II), lead(II), chromium(III), nickel(II) and cobalt(II) ions from environmental samples has been studied. The effects of electrolytes as matrix on the preconcentration were also investigated with the recoveries >95%. The 3 sigma detection limits for copper, cadmium, lead, chromium, nickel and cobalt ions were found to be 0.25, 0.32, 0.73, 0.45, 0.50 and 0.41 microg/l, respectively. The relative standard deviation was <10% for the determination of analytes. The procedure was validated by analysis of a NRCC-SLRS 4 Riverine Water, SRM 1573a Tomato leaves and IAEA 336 Lichen standard reference materials. The developed method was successively utilized for the determination of Cu(II), Cd(II), Pb(II), Cr(III), Ni(II) and Co(II) in various samples including natural waters, wheat and human hair by flame atomic absorption spectrometry (FAAS) with satisfactorily results (recoveries>95% and R.S.D.'s<10%).
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PMID:Celtek clay as sorbent for separation-preconcentration of metal ions from environmental samples. 1644 23


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