Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methods for extraction, cleanup, and analysis of samples of water, mud, and fish containing trace quantities of Abate have been developed. Water was extracted by high-speed stirring of 10 ml of hexane in a 300-ml sample. The extracts were evaporated and analyzed by gas chromatography with a limit of detection of 0.00003 ppm. Dried mud samples were extracted by shaking with acetone. An aliquot of the acetone extract was diluted with water and the Abate extracted into 10 ml of hexane by high-speed stirring. The extracts were analyzed by gas chromatography. Fish were extracted with methylene chloride, cleaned up on a silica gel column, and analyzed by gas chromatography. The limit of sensitivity of the methods for mud and fish was found to be 0.001 ppm. Fish samples were stored for 3 weeks in 10% formalin containing 5% sodium thiosulfate without significant loss of Abate residues. A biological magnification of greater than 100 was observed in fish exposed to Abate for 16 hr at concentrations of 0.02 and 0.002 ppm.
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PMID:Storage and analysis of samples of water, fish, and mud from environments contaminated with abate. 6 56

Dansylation of phenolic steroids was carried out in chloroform-water and hexane-water two-phase systems with a tetrabutylammonium salt as phase transfer catalyst. Derivatization was complete within a few minutes on shaking at room temperature. Direct injection of part of the organic phase into a normal-phase liquid chromatography system was possible. The calibration graph of ethinyl estradiol, dansylated in a chloroform-water two-phase system, was linear over three orders of magnitude with a correlation coefficient of 0.993 (n = 8). The detection limit of dansylated ethinyl estradiol was 100 pg (signal-to-noise ratio = 2). The reproducibility of the derivatization at an analyte concentration of 200 ng/ml in chloroform was 4.1% (relative standard deviation; n = 5). A mechanism is proposed for the phase transfer catalysed dansylation of phenolic compounds.
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PMID:Rapid and simple dansylation of phenolic steroids using a two-phase system and phase transfer catalysis. 336 Aug 84

Analysis of plasma nonesterified fatty acids (NEFA) by gas-liquid chromatography requires procedures that are both lengthy and cumbersome. A 45-min direct methylation procedure was carried out at 24-29 degrees C on 150 microliter of plasma added with an internal standard in 5.0 ml of methanol-acetyl chloride 50:1 (v/v). To stop the reaction, 3 ml of 6.0% K2CO3 was added. After addition of 150 microliter of hexane, shaking and centrifugation, an aliquot of the upper phase was injected into the gas chromatograph. The specificity of the methylation reaction for NEFA without hydrolysis of other classes of plasma lipids was substantiated with appropriate standards. This one-step specific methylation procedure is superior to currently used methods.
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PMID:Specific methylation of plasma nonesterified fatty acids in a one-step reaction. 336 90

Modifications to a published method are described for the determination of deoxynivalenol (DON) in wheat by gas chromatography with electron capture quantitation of the heptafluorobutyrate derivative. In the modified method, DON is extracted by shaking the sample with methanol-water on a wrist-action shaker, followed by filtration through rapid flow paper. One concentration step is eliminated, and a hexane wash is incorporated to remove toluene from the silica gel column. Recoveries of DON from wheat samples spiked at 0.1, 0.5, and 1.0 ppm ranged from 77.3 to 86.3% and averaged 81.5%.
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PMID:Gas chromatographic determination of deoxynivalenol in wheat. 664 61

New oxidimetric titrants, bromamine T, dibromohydantoin, N-bromophthalimide, and N-bromosuccinimide, were applied to the determination of ephedrine.HCl, norephedrine.HCl, and methyldopa. Direct potentiometric and visual indicator titration methods as well as back-titration procedures have been developed for their determination. Oxidation of ephedrine and norephedrine produces benzaldehyde, which is extracted from pH 11.0 phosphate buffer with ether or hexane and determined spectrophotometrically at 242 nm. Beer's law is obeyed in the concentration range from 0.2 to 2 mg ephedrine.HCl and from 0.15 to 1.9 mg norephedrine.HCl. Methyldopa is determined titrimetrically and spectrophotometrically. In addition, this drug acts as a self-indicator: Solutions change from colorless to red, which gradually disappears with continuous addition of brominating agent and shaking. Phosphate buffer is used to produce adrenochrome, characterized by its pink color which can be measured at 485 nm in a working range from 40 to 650 micrograms.
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PMID:Spectrophotometric and titrimetric determination of certain adrenergic drugs, using organic brominating agents. 675 41

Fortified milks were saponified overnight at room temperature with 1% ethanolic pyrogallol and KOH. The digest was extracted with hexane after adding water and ethanol, and the extract was washed consecutively with 5% KOH, water, and 55% aqueous ethanol to remove polar lipids. After evaporation, the residue was first chromatographed on a column of 5 micrometer silica. A fraction containing vitamin D was collected, evaporated, and rechromatographed on a reverse phase column for the separation and quantitation of vitamins D2 and D3. Recovery was 96-99% and the coefficient of variation was 3% (8 replicates). Infant formula was diluted and then saponified and extracted as in the analysis of milk. Margarine was saponified by shaking overnight with 1% ethanolic pyrogallol and 80% KOH. Water and ethanol were added to the digest before extraction. Extracts from formula and margarine were chromatographed as milk except, before HPLC, the extract was dissolved in isopropanol-hexane (1 + 99) and passed through 5 cm alumina in a Pasteur pipet, and the concentration of isopropanol in the first high performance liquid chromatographic (HPLC) solvent system was halved to improve the separation of vitamin D from other absorbing lipids. Usually several peaks were obtained during the final HPLC analysis, and the identification of vitamins D2 and D3 was less certain than in the analysis of milk. The coefficients of variation for formula and margarine were 6% (5 replicates) and 9% (6 replicates), respectively.
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PMID:High performance liquid chromatographic determination of vitamin D in fortified milks, margarine, and infant formulas. 709 44

Several techniques were evaluated for extracting triphenyl phosphate (TPP), 14C-labeled TPP, cresyl diphenyl phosphate, and tricresyl phosphate isomers (o-TCP, m-TCP, and p-TCP) from fish and sediment samples. Extracts of fish samples were cleaned up by gel permeation chromatography/alumina column chromatography; sediment extracts received alumina treatment only. Compounds were determined by gas-liquid chromatography (GLC) with nitrogen-phosphorus detection. Methanol/Polytron and hexane/ball mill extraction of fish samples fortified at 0.01, 0.1, and 1.0 microgram/g levels gave overall recoveries of the 5 compounds of 89 and 97%, respectively. Methanol recovered more radioactivity (97%) from fish exposed to 14C-TPP in aquaria for 24 h than did hexane from fish exposed for 16 h (79%). Refluxing fortified sediment (0.05 and 0.5 microgram/g) with methanol-water (9 + 1) gave significantly higher recoveries (88%) of the 5 triaryl phosphates than did dichloromethane-methanol (1 + 1) reflux or acetone-hexane (1 + 1) Soxhlet extraction. Recoveries of TPP and o-, m- and p-TCP from fortified river water (0.5, 5.0, and 50 microgram/L) by shaking with dichloromethane ranged from 91 to 118%. Some problems were encountered with interfering GLC peaks at low (microgram/g) levels in fish and sediment extracts despite the use of nitrogen-phosphorus specific detectors.
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PMID:Extraction and cleanup of fish, sediment, and water for determination of triaryl phosphates by gas-liquid chromatography. 720 13

A method is described for the simultaneous detection of ubiquinol-10 and ubiquinone-10 in human plasma. In this procedure, heparinized human plasma was mixed with 5 vol of methanol and 10 vol of hexane. After vigorous shaking and centrifugation, an aliquot of the hexane phase (5 microl) was injected immediately and directly onto a reversed-phase HPLC to minimize the oxidation of ubiquinol to ubiquinone. A post-separation, on-line reduction column converts ubiquinone to ubiquinol which is quantified by electrochemical detection. The detection limit of plasma ubiquinol-10 and ubiquinone-10 is about 4 nM with excellent reproducibilities. Tocopherols, lycopene, and beta-carotene are also detectable in this method. In addition, free cholesterol, and cholesteryl esters can be quantified by their absorption at 210 nm. Using this method we have determined the ratio of ubiquinol to ubiquinone is about 95/5 in human plasma from healthy donors. We suggest that this method will be useful since the ratio of ubiquinol to ubiquinone has been suggested as a good marker of oxidative stress.
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PMID:Simultaneous detection of ubiquinol and ubiquinone in human plasma as a marker of oxidative stress. 923

Oxidative stress is defined as a disturbance in the prooxidant-antioxidant balance in favor of the former and has been suggested to be a relevant factor in aging as well as in different pathological conditions, such as heart attack, diabetes, and cancer. Ubiquinol is very sensitive against oxygen radicals and gives ubiquinone as an oxidation product. Therefore, the ratio of ubiquinol to ubiquinone should be a good marker of oxidative stress because of its definition. A method for the simultaneous detection of ubiquinol-10 and ubiquinone-10 in human plasma is described. Heparinized human plasma was mixed with 5 volumes of methanol and 10 volumes of hexane. After vigorous shaking and centrifugation, the hexane phase (5 microliters) was injected immediately and directly on to reverse-phase HPLC equipped with an on-line reduction column and an electrochemical detector in order to avoid the oxidation of ubiquinol to ubiquinone. It was found that the ratio of ubiquinol-10 to ubiquinone-10 was about 95/5 in human plasma from healthy donors. A significant increase in the oxidized form (ubiquinone-10) content was observed in plasmas of patients with hepatitis, cirrhosis, and hepatoma when compared with normal subjects, suggesting increased oxidative stress in these patients.
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PMID:Plasma ratio of ubiquinol and ubiquinone as a marker of oxidative stress. 926 9

A rapid normal-phase high-performance liquid chromatographic method for the quantitative determination of indole and skatole in pig back fat samples has been developed. The compounds were extracted by shaking the samples at ambient temperature in hexane-2-propanol (92:8, v/v). The sample preparation procedure was simple because it was not necessary to remove the fat from the samples. The compounds were separated on a 250 x 4.6 mm I.D., 5 micron Hypersil aminopropylsilica column. Fluorescence (excitation at 280 nm and emission at 360 nm) was used for selective detection. Recoveries for skatole and indole, relative to the internal standard, were 10.3 +/- 0.9% and 99.6 +/- 4.4%, respectively. Linearity determined in fat samples was in the range of 0.05-1 microgram/g and the correlations observed were R2 = 0.9914 for the indole and R2 = 0.9916 for skatole.
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PMID:Rapid determination of skatole and indole in pig back fat by normal-phase liquid chromatography. 967 18


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