Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024591 (malignant hyperthermia)
 2,353 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of these experiments was to determine if the Ca2+ agonist BAY K 8644 and the Ca2+ antagonist nifedipine alter the mechanical responses of malignant hyperthermia-susceptible (MHS) skeletal muscle to halothane and caffeine. Muscle fiber bundles were dissected from MHS porcine skeletal muscle and exposed to BAY K 8644 (10 microM), nifedipine (1 microM), low-Ca2+ media [Ca2+ replaced by 1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid], or diltiazem (30 microM) administered alone and with halothane (3%) or caffeine (0.5-0.8 mM). When administered alone, both halothane and BAY K 8644 evoked a significant change in resting tension (i.e., contracture) of 193.7 +/- 61.0 and 51.9 +/- 21.5 mN/cm2, respectively. When administered in combination, BAY K 8644 had no effect on the magnitude of the halothane contracture (195.2 +/- 58.6 mN/cm2) but reduced its onset time from 306.7 +/- 36.3 to 105.9 +/- 8.9 s. Nifedipine, low Ca2+, and diltiazem significantly reduced the halothane contracture (103.1 +/- 30.3, 123.1 +/- 20.6, and 112.6 +/- 16.2 mN/cm2, respectively) but had no effect on its onset time. In addition, low Ca2+ reduced the magnitude of the BAY K 8644 contracture (8.2 +/- 2.1 mN/cm2). BAY K 8644 also increased contractures induced by low caffeine concentrations (0.5-2.0 mM) but did not alter contractures induced by 4.0 and 8.0 mM caffeine, whereas nifedipine, low Ca2+, and diltiazem had no effect on these contractures. These results suggest that extracellular Ca2+ influx may have some influence on halothane but not on caffeine contractures of MHS skeletal muscle.
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PMID:BAY K 8644 and nifedipine alter halothane but not caffeine contractures of malignant hyperthermic muscle fibers. 171 70

Multiple headspace solid-phase microextraction (MHS-SPME) combined with gas chromatography-nitrogen phosphorus detector is proposed to determine the toxic contaminant ethyl carbamate (EC) in various alcoholic beverages after matrix modification. The remarkable feature of this method is that matrix effect, which commonly appears in SPME-based analysis, is avoided by determining the total amount of the analyte in the sample. To increase the sensitivity of the method, a novel polyethylene glycol/hydroxy-terminated silicone oil fiber was developed by sol-gel technique and applied for the analysis. Owing to the high polarity and hydrophilia of EC, an important problem still remains because the adsorption by sample matrix causes low transport of EC to the headspace and thus invalidates MHS-SPME for quantification. Mixing with anhydrous sodium sulphate, the sensitivity of the method can be improved. A Taguchi's L(16) (4(5)) orthogonal array design was employed to evaluate potentially significant factors and screen the optimum conditions for MHS-SPME of EC. Under the optimized conditions, limit of detection of 0.034 mg L(-1) was obtained. Relative standard deviation of replicate samples (n=6) was 2.19%. The proposed method was linear in the range of 0.04-100 mg L(-1), and the coefficient of determination was 0.9997. The method was used to determine EC in various alcoholic beverages. The concentrations obtained were compared with those obtained by standard addition method and no statistically significant differences were observed.
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PMID:Multiple headspace solid-phase microextraction of ethyl carbamate from different alcoholic beverages employing drying agent based matrix modification. 2172 69

A method based on multiple headspace solid-phase microextraction (MHS-SPME) combined with gas chromatography for determining ethyl carbamate (EC) in various alcoholic beverages was established. A novel polyethylene glycol/hydroxy-terminated silicone oil fiber was used instead of commercial ones because of its high extraction ability. Anhydrous sodium sulphate was added to modify the matrix and the extraction efficiency of EC was greatly improved. The optimum conditions for MHS-SPME were as follows: extraction time, 10 min; extraction temperature, 35 degrees C; Na2SO4 addition, 4.0 mg Na2SO4 per microliter of sample; volume of sample, 20 microL. The proposed method was linear in the range of 0.04 to 100 mg/L with a correlation coefficient of 0.999 7. The limit of detection was 34 microg/L and the repeatability of six replicates was 2.19%. The method was used to determine EC in various alcoholic beverages. The concentrations obtained were compared with those obtained by standard addition method and no statistically significant differences were observed. The application of MHS-SPME avoids the matrix effect, which commonly appears in SPME-based analysis. The results indicate that MHS-SPME has a great potential for EC quantification of complex samples due to its simplicity, sensitivity, reliability, ease of operation and environmental protection, especially for the analysis of a large number of samples in different matrices.
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PMID:[Multiple headspace solid-phase microextraction after matrix modification for the determination of ethyl carbamate in alcoholic beverages using gas chromatography]. 2212 30