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)

A method for the selective quantitative determination of inorganic arsenic [As(III) + As(V)] in seafood was developed. In order to do so, various procedures for the solubilization and extraction of inorganic arsenic quoted in the literature were tested. None provided satisfactory recoveries for As(III) and As(V) in real samples. Consequently, a methodology was developed which included solubilization with HCl and subsequent extraction with chloroform. The arsenic was solubilized in 9 mol l-1 hydrochloric acid. After reduction by hydrobromic acid and hydrazine sulfate, the inorganic arsenic was extracted into chloroform, back-extracted into 1 mol l-1 HCl, dry-ashed, and quantified by hydride generation-atomic absorption spectrometry (HG-AAS). The analytical features of the method are as follows: detection limit, 3.07 ng g-1 As (fresh mass); precision (RSD), 4.0%; recovery, As(III) 99%, As(V) 96%. In the optimized conditions, other arsenic species--dimethylarsinic acid (DMA), arsenobetaine (AB), arsenocholine (AC) and tetramethylarsonium-ion (TMA+)--were not co-extracted. However, different percentages of minor species were extracted with chloroform: monomethylarsonic acid (MMA) 100%, and trimethylarsine oxide (TMAO) 3-10%. Real samples and reference materials of seafood (DORM-1, DORM-2, TORT-2, CRM-278 and SRM-1566a) were analyzed. The analysis of DORM-1 provided an inorganic arsenic value of 124 +/- 4 ng g-1 As, dry mass (dm), which is very close to the value obtained by other authors using high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) and ionic chromatography-hydride generation-atomic absorption spectrometry (IC-HG-AAS).
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PMID:Optimization of the solubilization, extraction and determination of inorganic arsenic [As(III) + (As(V)] in seafood products by acid digestion, solvent extraction and hydride generation atomic absorption spectrometry. 1060 84

Six arsenic compounds including arsenocholine, arsenobetaine, dimethylarsinic acid, methylarsonic acid, arsenous acid and arsenic acid were separated by high-performance liquid chromatography (HPLC) on a Hamilton PRP-X100 anion-exchange column using isocratic elution and detected by inductively coupled plasma mass spectrometry (ICP-MS). This analytical procedure was applied to the speciation of arsenic compounds in human urine. The influence of urine matrix on the separation of arsenic compounds was evaluated and the determination of arsenic compounds was not hampered by the ArCl interference which has often been encountered in ICP-MS. Three human urine reference materials, SRM 2670 normal level, SRM 2670 elevated level and Lyphocheck urine metal control 1, were analyzed with respect to arsenic compounds by HPLC-ICP-MS. The results were found to be in good agreement with the certified total arsenic concentration in the reference materials. Six arsenic compounds were detected. Arsenobetaine was found to be present in all of the investigated human urine reference materials.
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PMID:Arsenic speciation in human urine reference materials using high-performance liquid chromatography with inductively coupled plasma mass spectrometric detection. 1061 78

The stability of arsenic, selenium, antimony and tellurium species in water and urine (NIST SRM 2670n) as well as in extracts of fish and soil certified reference materials (DORM-2 and NIST SRM 2710) has been investigated. Stability studies were carried out with As(III), As(V), arsenobetaine, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), phenylarsonic acid (PAA), Se(IV), Se(VI), selenomethionine, Sb(III), Sb(V) and Te(VI). Speciation analysis was performed by on-line coupling of anion exchange high-performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS). Best storage of aqueous mixtures of the examined species was achieved at 3 degrees C whereas at -20 degrees C species transformation especially of selenomethionine and Sb(V) took place and a new selenium species appeared within a period of 30 days. Losses and species transformations during extraction processes were investigated. Extraction of the spiked fish material with methanol/water led to partial conversion of Sb(III), Sb(V) and selenomethionine to two new antimony and one new selenium species. The other arsenic, selenium and tellurium species were almost quantitatively extracted. For soil spiked with MMA, PAA, Se(IV) and Sb(III), recoveries after extraction with water and sulfuric acid (0.01 mol/L) were below 20%.
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PMID:Stability studies of arsenic, selenium, antimony and tellurium species in water, urine, fish and soil extracts using HPLC/ICP-MS. 1122 May 82

A speciation technique for arsenic has been developed using an anion-exchange high-performance liquid chromatography/inductively coupled argon plasma mass spectrometer (HPLC/ICP MS). Under optimized conditions, eight arsenic species [arsenocholine, arsenobetaine, dimethylarsinic acid (DMA(V)), dimethylarsinous acid (DMA(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)), arsenite (As(III)), and arsenate (As(V))] can be separated with isocratic elution within 10 min. The detection limit of arsenic compounds was 0.14-0.33 microg/L. To validate the method, Standard Reference Material in freeze-dried urine, SRM-2670, containing both normal and elevated levels of arsenic was analyzed. The method was applied to determine arsenic species in urine samples from three arsenic-affected districts of West Bengal, India. Both DMA(III) and MMA(III) were detected directly (i.e., without any prechemical treatment) for the first time in the urine of some humans exposed to inorganic arsenic through their drinking water. Of 428 subjects, MMA(III) was found in 48% and DMA(III) in 72%. Our results indicate the following. (1) Since MMA(III) and DMA(III) are more toxic than inorganic arsenic, it is essential to re-evaluate the hypothesis that methylation is the detoxification pathway for inorganic arsenic. (2) Since MMA(V) reductase with glutathione (GSH) is responsible for conversion of MMA(V) to MMA(III) in vivo, is DMA(V) reductase with GSH responsible for conversion of DMA(V) to DMA(III) in vivo? (3) Since DMA(III) forms iron-dependent reactive oxygen species (ROS) which causes DNA damage in vivo, DMA(III) may be responsible for arsenic carcinogenesis in human.
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PMID:Identification of dimethylarsinous and monomethylarsonous acids in human urine of the arsenic-affected areas in West Bengal, India. 1130 25

The abilities of various extractants to recover four arsenic species [As(iii), As(v), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA)] from soils spiked with 20 micro g g(-1) As were investigated. The extractants were water, buffer solutions (citrate and ammonium dihydrogen phosphate), acidic solutions (phosphoric acid and acetic acid), a basic solution (sodium hydroxide) and household chemicals (vinegar and Coca Cola). Gentle shaking at room temperature with each extractant for 24 h gave different recoveries for the different arsenic species. With 0.1 M NaOH solution 46% As(iii), 53% DMA, 100% MMA and 84% As(v) were recovered. A rapid extraction procedure using a sonicator probe has been developed to obtain higher extraction efficiencies. Extracts of arsenic-spiked soil, SRM 2711 Montana soil and SRM 2709 San Joaquin soil were analyzed by HPLC-ICP-MS. In the SRM water extracts, DMA and MMA were identified in addition to inorganic arsenic. The solution detection limits (3s) were 0.1, 0.12, 0.13 and 0.15 ng mL(-1) for As(iii), DMA, MMA and As(v), respectively for HPLC-ICP-MS.
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PMID:Extraction of arsenic species from spiked soils and standard reference materials. 1528 14

A capillary electrophoresis-inductively coupled plasma-mass spectrometric (CE-ICP-MS) method for the speciation of six arsenic compounds, namely arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid, dimethylarsinic acid, arsenobetaine and arsenocholine is described. The separation has been achieved on a 70 cm length x 75 microm ID fused-silica capillary. The electrophoretic buffer used was 15 mM Tris (pH 9.0) containing 15 mM sodium dodecyl sulfate (SDS), while the applied voltage was set at +22 kV. The arsenic species in biological tissues were extracted into 80% v/v methanol-water mixture, put in a closed centrifuge tube and kept in a water bath, using microwaves at 80 degrees C for 3 min. The extraction efficiencies of individual arsenic species added to the sample at 0.5 microg As/g level were between 96% and 107%, except for As(III), for which it was 89% and 77% for oyster and fish samples, respectively. The detection limits of the species studied were in the range 0.3-0.5 ng As/mL. The procedure has been applied for the speciation analysis of two reference materials, namely dogfish muscle tissue (NRCC DORM-2) and oyster tissue (NIST SRM 1566a), and two real-world samples.
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PMID:Speciation of arsenic compounds in fish and oyster tissues by capillary electrophoresis-inductively coupled plasma-mass spectrometry. 1575 2

This paper describes a novel hydride atomizer based on atmospheric pressure dielectric barrier discharge (DBD) plasma. The plasma was generated with a 3700-V, 20.3-kHz, and 5-W electrical power supply and easily sustained with inert gases (He or Ar) at a flow rate of 250 mL.min(-1) after optimization. However, it cannot be sustained with N2. This atomizer offers the advantages of low operation temperature and low power consumption in comparison with the currently used electrothermal quartz atomization operated at 900 degrees C with a power supply of several hundred watts. To confirm the utility of the proposed atomizer, four arsenic species (As(III), As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA)) were determined by the present atomization technique. A hyphenation of HPLC coupled to hydride generation AAS with the optimized DBD atomizer has been successfully used for the speciation of arsenic in order to demonstrate the potential of this atomizer in the present study. The characteristics of the DBD atomizer and the effects of different parameters (discharge gas, gas flow rate, voltage, HCl concentration, KBH4 concentration) are discussed in the paper. Compared with other hydride atomization techniques, the proposed method shows the following features: (1) small size (70 mm x 15 mm x 5 mm), which is preferable for the miniaturization of the total analytical system; (2) low power consumption (< or =5 W), which indicates the possibility of the development of portable, fieldable analytical instrumentation for in situ detection using battery as power supply; (3) low atomizer temperature (approximately 70 degrees C), which is in favor of the compactness of the total instruments; (4) avoidance of residue moisture removal in comparison with the existed GD system, which leads to the facility of the system. The analytical figures of the present technique were evaluated. The detection limits of As(III), As(V), MMA, and DMA obtained with HG-DBD-AAS were 1.0, 11.8, 2.0, and 18.0 microg.L(-1), respectively. The accuracy of the system was verified by the determination of arsenic in reference material of orchard leaves SRM 1571. The concentration of As determined by the present method agreed well with the reference values. The speciation of arsenic in the freeze-dried urine SRM 2670 were carried out, and the results obtained were in agreement with the results of HPLC-ICPMS and the reported values by other laboratories.
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PMID:Atomization of hydride with a low-temperature, atmospheric pressure dielectric barrier discharge and its application to arsenic speciation with atomic absorption spectrometry. 1644 62

A sensitive and robust method for the determination of seven inorganic and organic arsenic species was developed using ion exchange chromatography combined with inductively coupled plasma mass spectrometry (IC-ICP-MS). Both anion and cation exchange columns were used in a complementary fashion. Arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)) were selectively separated by an anion exchange column using sodium hydroxide (NaOH) gradient elution, while monomethylarsonous acid (MMA(III)), dimethylarsinous acid (DMA(III)) and arsenobetaine (AsB) were separated by a cation exchange column using 70 mM nitric acid as the mobile phase. Baseline separation, high repeatability and low detection limits (0.10-0.75 ng mL(-1)) were achieved. The spiked urine samples were analyzed with this method to evaluate the matrix effect on the method. The results suggest 1-10 dilutions should be made to urine samples before sample injection for the anion exchange analysis to minimize the matrix effect. To validate the method, a new standard reference material (NIST SRM-2670a) was also analyzed. The arsenic species in NIST SRM-2670a were determined by this method, and the sum of their concentrations agreed well with the total arsenic content certified for NIST SRM-2670a. Moreover, this method was applied to measure arsenic species in urine samples from one subject living in New Jersey who drank well water contaminated with arsenic. By this method, two key arsenic metabolites, MMA(III) and DMA(III), were found to be present in these urine samples, which has previously been rarely reported.
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PMID:Arsenic speciation analysis of human urine using ion exchange chromatography coupled to inductively coupled plasma mass spectrometry. 1772 11

In this study, a rapid and sensitive high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) determination of primary As species in fish tissues and urine is reported. The separation was achieved on an Altima C18 column with a mobile phase containing citric acid and hexanesulfonic acid (pH 4.5). As(V), monomethylarsonic acid (MMA), As(III), dimethylarsinic acid (DMA) and arsenobetaine (AsB) were separated in less than 4 min with retention times of 83, 99, 130, 166 and 208 s, respectively. This separation of five species in less than 4 min should be attractive to those interested in As speciation. The quantification limits were 44, 56, 94, 64, 66 ng l(-1) and the relative standard deviations (R.S.D.) for day-to-day injections of As at 2 mug l(-1) were 2.0, 3.1, 2.4, 3.8 and 4.0%. The procedure was tested using two reference materials (DORM-2 dogfish muscle tissue, NIST SRM 2670 Freeze-dried Urine, normal level) and then applied to real-world samples. The results obtained demonstrate the suitability of the procedure for screening and quantification at physiological levels of primary As species in biological samples.
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PMID:Determination of As(III), As(V), monomethylarsonic acid, dimethylarsinic acid and arsenobetaine by HPLC-ICP-MS: analysis of reference materials, fish tissues and urine. 1896 22

A rapid, sensitive and economic method has been developed for the direct determination of toxic species of arsenic present in fish and mussel samples. As(III), As(V), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) were determined by hydride generation-atomic fluorescence spectrometry using a series of proportional equations without the need of a chromatographic previous separation. The method is based on the extraction of arsenic species from fish through sonication with HNO(3) 3moll(-1) and 0.1% (m/v) Triton and washing of the solid phase with 0.1% (m/v) EDTA, followed by direct measurement of the corresponding hydrides in four different experimental conditions. The limit of detection of the method was 0.62ngg(-1) for As(III), 2.1ngg(-1) for As(V), 1.8ngg(-1) for MMA and 5.4ngg(-1) for DMA, in all cases expressed in terms of sample dry weight. The mean relative standard deviation values (R.S.D.) in actual sample analysis were: 6.8% for As(III), 10.3% for As(V), 8.5% for MMA and 7.4% for DMA at concentration levels from 0.08mgkg(-1) As(III) to 1.3mgkg(-1) DMA. Recovery studies provided percentages greater than 93% for all species in spiked samples. The analysis of SRM DORM-2 and CRM 627 certified materials evidenced that the method is suitable for the accurate determination of arsenic species in fish.
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PMID:Non-chromatographic speciation of toxic arsenic in fish. 1897 69


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