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)

A rapid sensitive technique was developed for the analysis of di-2-ethylhexyl phthalate (DEHP) in plasma stored in plastic bags by using high performance liquid chromatography (HPLC) with UV detection and a Hypersil ODS column. The compound was easily and efficiently extracted with a mixture of sodium hydroxide and acetonitrile, which allowed the deproteinization of plasma samples. The recovery was greater than 95% and the intra- and inter-assay coefficients of variation were better than 6.5%. The results obtained showed that the amount of DEHP accumulated in plasma varied according to different parameters and depended on the storage conditions (time, temperature and shaking) and also on the lipid content of the stored plasma and the sterilization process of the PVC bags.
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PMID:Rapid determination by high performance liquid chromatography of di-2-ethylhexyl phthalate in plasma stored in plastic bags. 186 66

A simple, specific and rapid reversed-phase high-performance liquid chromatographic (HPLC) procedure for sotalol determination is described requiring small plasma volumes. The high recovery of sotalol from plasma and the high precision of measurement obviate the need for an internal standard. Plasma samples (300 microliters) were deproteinised with 50 microliters of 70% (w/w) perchloric acid in disposable glass tubes. After vortex-mixing and centrifugation, 30 microliters of 4 M K2HPO4 were added followed by gentle shaking. A 20-microliters aliquot was then injected (by autosampler) for HPLC analysis. Chromatography was performed on a glass-lined 250 mm x 4 mm 5-micron C18 steel column. The mobile phase was 6% (v/v) acetonitrile in 0.08 M KH2PO4 buffer (pH 4.6). The flow-rate was 0.8 ml/min. Detection was by fluorescence with excitation and emission wavelengths at 235 and 310 nm, respectively. The retention time for sotalol was 7.1 min. Calibration was linear from 0.16 to 10 micrograms/ml in plasma (r greater than 0.999 for detector response to sotalol). The minimum concentration for quantitation was 0.08 micrograms/ml [within assay coefficient of variation (C.V.) less than 5%]. Recovery was near quantitative (greater than 98%) and replicate (intra-assay precision was less than 5% C.V.). Analysis of samples (n = 10) at concentrations of 0.42 and 4.2 micrograms/ml gave mean values of 0.44 and 4.3 micrograms/ml, respectively. The inter-assay C.V. values were 4.5 and 2.2%, respectively. Other clinically used antiarrhythmic drugs did not interfere. This assay can be performed using other commercial C18 analytical columns by suitable adjustment of mobile phase flow-rate and acetonitrile composition.
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PMID:Simplified procedure for the determination of sotalol in plasma by high-performance liquid chromatography. 187 2

A high-performance liquid chromatographic method with fluorimetric detection for the quantification of riboflavin (RB), riboflavin 5'-phosphate (FMN), and flavin adenine dinucleotide (FAD) in plasma, whole blood, and urine is described. Under isocratic conditions with a reversed-phase column, the compounds are completely resolved and eluted within 9 min. Plasma proteins are precipitated with acetonitrile followed by shaking the aqueous phase with chloroform. Urine samples are diluted and injected directly. The reproducibility of this method for the quantification of RB in plasma has a between-day coefficient of variation of 6%. The application of this method is illustrated by analyzing plasma and urine samples from a human subject who received an intravenous dose of FMN equivalent to 25 mg of RB.
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PMID:Quantification of riboflavin, riboflavin 5'-phosphate and flavin adenine dinucleotide in plasma and urine by high-performance liquid chromatography. 344 41

A liquid chromatographic (LC) method for determining furazolidone in finished feeds and premixes was collaboratively studied. Finished feed sample is extracted with acetone-water (93 + 7) on a Goldfisch apparatus, extracting solvent is removed, and the residual material is dissolved in warm DMF. A solution of tetraethylammonium bromide is added, the fat layer is removed, and the sample is clarified by filtration and injected onto a reverse phase LC system with detection at 365 nm. Premixes, extracted by shaking with DMF and diluted so that the final furazolidone concentration is about 55 micrograms/mL, are chromatographed and detected the same as finished feed samples, using a mobile phase of acetonitrile-2% acetic acid (20 + 80). Ten commercial feed samples were preweighed and supplied to 14 collaborators. The 5 matched pairs were chosen to represent the following allowed levels: 0.0055, 0.022, 0.033, 2.2, and 22%. Two familiarization samples at the 0.0055 and 11% levels were also supplied. Instructions called for a single analysis of each sample. Two results were eliminated by the Dixon test. The coefficients of variation, following treatment by the ranking test, ranged from 2.0 at the 22% level to 6.5 at the 0.0055% level. Calculated F-values are not significant (P greater than 0.01) except for the 0.0055% level samples extracted overnight. This method has been adopted official first action.
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PMID:Liquid chromatographic method for determination of furazolidone in premixes and complete feeds: collaborative study. 405 21

Sulfonamide drugs are extracted from feed and feed premixes by shaking with 0.15N HCl in 25% methanol. The extract is diluted, clarified, and chromatographed on a reverse phase C18 column. Mobile phases used are methanol-2% acetic acid (35 + 65) and acetonitrile-2% acetic acid (18 + 82) for sulfamethazine (SMT) and sulfathiazole (STZ), respectively. A solution of dimethylaminobenzaldehyde (DMAB) is added to the column eluate and the resulting sulfonamide-DMAB complex is detected at 450 nm. The method was tested for linearity, recovery, and precision across a broad sample range. Recovery was 100.6 +/- 2.3% and 96.3 +/- 1.6% for STZ and SMT, respectively. Linearity was excellent (r2 = 0.9985 for STZ and r2 = 0.9996 for SMT) as was within-day precision (RSD = 2.00% for STZ and 1.52% for SMT). The method was compared with the Bratton-Marshall colorimetric method. Analysis of 14 STZ and 15 SMT samples failed to detect any bias between the 2 methods. Some practical aspects of the use of this technique are discussed.
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PMID:Use of post-column derivatization in liquid chromatographic determination of sulfamethazine and sulfathiazole in feeds and feed premixes. 711 88

New pre-column derivatizing reagents: phthalic anhydride, 3-nitrophthalic anhydride, diphenic anhydride, 1,8-naphthalic anhydride and diphenylmaleic anhydride have been developed for resolving chiral compounds having amine groups. Although all of these agents produce derivatives with high molar absorptivities, the later two also fluoresce. Upon derivatization, aromatic analytes containing free carboxylic groups are produced. Both of these moieties enhance chiral recognition on cyclodextrin-based columns. The derivatization reaction is carried out at room temperature by shaking a buffered aqueous solution of a sample with an acetonitrile solution of the reagent. The reaction is fast and proceeds without any detectable racemization. The labeled compounds have favorable chromatographic properties which are demonstrated by resolution of a number of chiral compounds on cyclodextrin-bonded phases operated with non-aqueous polar organic eluents. The selectivity and good efficiency of this system contributes to its high sensitivity and in its applicability for detecting low levels of enantiomeric impurities. The detection limit is in the picomole range and less than 0.1% enantiomeric impurities can be determined in some cases.
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PMID:Sensitive enantiomeric separation of aliphatic and aromatic amines using aromatic anhydrides as nonchiral derivatizing agents. 780 65

The finding that ascending cholinergic systems are severely degenerated in Alzheimer's disease has driven the search for a cholinomimetic therapy. Adverse effects observed with cholinesterase inhibitors and high-efficacy muscarinic agonists led us to design compounds with an improved profile. SB 202026 (R-(Z)-(+)-alpha-(methoxyimino)-1-azabicyclo[2.2.2] octane-3-acetonitrile) displaced [3H]-oxotremorine-M from muscarinic receptors in the rat brain with high affinity (IC50 = 14 nM), a potency similar to that of oxotremorine-M itself (IC50 = 13 nM), but exhibited low affinity for cholinergic nicotinic receptors and other neuroreceptors. In studies using cloned human muscarinic receptors, SB 202026 possessed approximately equal affinity in displacing [3H]-quinuclidinyl benzilate from all muscarinic receptor subtypes. In functional models in vitro, SB 202026 caused maximal depolarization of the rat superior cervical ganglion at low concentrations (300 nM) (M1-mediated effect), while producing a lower maximal effect than the high-efficacy agonists oxotremorine-M and carbachol on M2-mediated release of ACh and M3-mediated smooth muscle contraction (guinea pig ileum), respectively. The functional selectivity and partial agonist profile seen in vitro were reflected in vivo through potent cognition-related activity (M1-induced increase in hippocampal EEG power) combined with low efficacy, compared with arecoline or oxotremorine, on induction of bradycardia (M2-mediated response), hypotension (via M3-mediated vasorelaxation) and tremor (thought to be mediated by M3 receptors). The foregoing profile of SB 202026 predicted that cognition-enhancing activity would be achieved at doses below those that initiate undesirable side effects, and this has subsequently been demonstrated in rodents, marmosets and humans.
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PMID:SB 202026: a novel muscarinic partial agonist with functional selectivity for M1 receptors. 939 77

A liquid chromatographic (LC) method for the analysis of sulfamethazine (SMT) in complete swine and cattle feed was collaboratively studied. The method uses post-column derivatization with dimethylaminobenzaldehyde and detection at 450 nm. To 5g finely ground feed, extractant (0.2N HCl + 1.5% diethylamine in 25% methanol), and internal standard solutions are added, and the SMT is extracted by shaking for 1 h. Clarified extract (high-level sample extract diluted to a target concentration of ca 5.5 microg/mL) is chromatographed on a Cla reversed-phase LC column with acetonitrile-2% acetic acid (17 + 83) mobile phase. Sulfamerazine is used as an internal, or surrogate standard to correct for variable recovery of sulfamethazine from a variety of feed matrixes. Six Youden matched-pair samples were sent to 10 collaborators in Korea, Canada, and the United States. Label claims on the commercial feeds ranged from 0.0077 to 0.22% SMT. The SMT mean recovery as determined from the 5 samples with known analyte content was 99.8%. The within-laboratory relative standard deviation (repeatability) ranged from 0.28 to 4.72%. Among-laboratory (including within-laboratory) relative standard deviation (reproducibility) ranged from 1.26 to 4.87%. The authors recommend the method for AOAC INTERNATIONAL Official First Action status.
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PMID:Determination of sulfamethazine in swine and cattle feed by reversed-phase liquid chromatography with post-column derivatization: collaborative study. 1077 62

A method is reported for the determination of cyromazine and melamine residues in soil. Soil samples are extracted twice via mechanical shaking, each time with 70% acetonitrile/30% 0.050 M ammomium carbonate for 30 min. An aliquot portion of the pooled extracts is subjected to strong cation exchange (SCX) purification on AG 50W-X4 resin. Final analysis is accomplished using liquid chromatography-ultraviolet (LC-UV) detection at a wavelength of 214 nm. Confirmatory analyses can be performed using gas chromatography-mass selective detection (GC-MSD) in the selected ion monitoring (SIM) mode. The limit of detection (LOD) is 2.5 ng injected and the limit of quantification (LOQ) is 10 ppb when using LC-UV for the analysis of N-cyclopropyl-1,3,5-triazine-2,4, 6-triamine (cyromazine) and 1,3,5-triazine-2,4,6-triamine (melamine). The LOD is 0.050 ng injected and the LOQ is 10 ppb when using GC-MSD for confirmatory analyses. The mean procedural recoveries were 97 and 95% and the standard deviations were 16 and 11% for cyromazine and melamine, respectively (n = 24), when using LC-UV. The mean procedural recoveries were 107 and 92% and the standard deviations were 9.9 and 16% for cyromazine and melamine, respectively (n = 29), when using GC-MSD. The method validation study was conducted under U.S. EPA FIFRA Good Laboratory Practice Guidelines 40 CFR 160. The method also passed an Independent Laboratory Validation (ILV) as per U.S. EPA FIFRA Subdivision N.
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PMID:Analytical method for the determination of cyromazine and melamine residues in soil using LC-UV and GC-MSD. 1095 15

An improved analytical method was developed which may be applied to quality control of stevioside and rebaudioside A contents in dried leaves of Stevia rebaudiana before processing; in a selective sampling program searching for plants of higher yield in diterpene glycosides content; or when a large number of samples are sent to the laboratory for analysis. The procedure developed involves two steps: solvent extraction followed by an isocratic HPLC analysis. The sample, 1 g of dried leaves of S. rebaudiana, is ground and solvent-extracted with EtOH 70% (w/w) in Erlenmeyer flasks by shaking for 30 min in a 70 degrees C water bath. After the extract was cooled, it was filtered and analyzed by HPLC using an NH(2) column (250 x 4.6 mm) and a mixture of acetonitrile/water (80:20, v/v) as mobile phase, pH 5 adjusted with acetic acid. The detection was in the UV range at 210 nm (0.04 AUFS). Quantitation was performed by means of an external standard calibration curve for each analyte which had been obtained from standard solutions of pure stevioside and rebaudioside A. Working under these conditions there were no observed interference effects. The method saves time in sample preparation, and reduces sample handling and chromatographic analysis time, while having little loss of precision [coefficient of variation (CV%) between 1.8% and 3.0%] and recovery [between 98.5% and 100.5%]. The method was applied to 30 samples of S. rebaudiana from Misiones (Northeastern Argentina), and the stevioside content found ranged between 3.78 and 9.75% (weight) whereas Rebaudioside A content ranged between 1.62 and 7.27% (weight).
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PMID:Analysis of sweet diterpene glycosides from Stevia rebaudiana: improved HPLC method. 1159 85


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