The aim of the study was to describe the pharmacokinetics and selected pharmacodynamics of intravenous dexmedetomidine in horses. Eight adult horses received 5 μg/kg dexmedetomidine IV. Blood samples ...were collected before and for 10 h after drug administration to determine dexmedetomidine plasma concentrations. Pharmacokinetic parameters were calculated using noncompartmental analysis. Data from one outlier were excluded from the statistical summary. Behavioral and physiological responses were recorded before and for 6 h after dexmedetomidine administration. Dexmedetomidine concentrations decreased rapidly (elimination half‐life of 8.03 ± 0.84 min). Time of last detection varied from 30 to 60 min. Bradycardia was noted at 4 and 10 min after drug administration (26 ± 8 and 29 ± 8 beats/min respectively). Head height decreased by 70% at 4 and 10 min and gradually returned to baseline. Ability to ambulate was decreased for 60 min following drug administration, and mechanical nociceptive threshold was increased during 30 min. Blood glucose peaked at 30 min (134 ± 24 mg/dL) and borborygmi were decreased for the first hour after dexmedetomidine administration. Dexmedetomidine was quickly eliminated as indicated by the rapid decrease in plasma concentrations. Physiological, behavioral, and analgesic effects observed after dexmedetomidine administration were of short duration.
The primary objective of this study was to determine how yogurt ingredients affect aroma release in the mouth during eating. A model strawberry flavor consisting of ethyl butanoate, ethyl ...3-methylbutanoate, (Z)-hex-3-enol, 2-methylbutanoic acid, 5-hexylhydro-2(3H)-furanone, and 3-methyl-3-phenylglycidic acid ethyl ester was added to unflavored, unsweetened yogurt that had different added sweeteners and hydrocolloids. In all, 12 yogurt formulations were examined to determine the effects of gelatin, modified food starch, pectin, sucrose, high-fructose corn syrup, and aspartame on aroma release. Aroma release was monitored by breath-by-breath analysis (proton-transfer reaction−mass spectrometry) during eating of the test yogurts. Results showed aroma release of the ethyl butanoate, (Z)-hex-3-enol, and ethyl 3-methylbutanoate to be suppressed by sweeteners, with 55 DE high-fructose corn syrup having the greatest effect. Addition of thickening agents had no significant effect on the aroma release profiles of the compounds under study. Keywords: Proton-transfer reaction−mass spectrometry; yogurt; high-fructose corn syrup; aroma release; flavor release; breath-by-breath
To define the pharmacokinetic profile of propofol 5% microemulsion formulation in horses.
First, propofol was administered as bolus injection (2 mg kg−1) to six xylazine-sedated horses. Secondly, ...after sedation and bolus injection, propofol was maintained with continuous infusion for 3 h 8.1 (sd 3.2) mg kg−1 h−1 to the same six horses. Thirdly, in two horses, a commercial propofol was used for comparison. Response to noxious stimulation was used to evaluate analgesia. Venous blood samples were obtained to measure propofol plasma concentration using liquid chromatography-mass spectrometry analysis. The plasma concentrations were related to the anaesthesia characteristics to determine the ED50.
The pharmacokinetic profile of propofol is best characterized by a non-compartmental model. The mean (confidence interval) for area under plasma concentration–time curve, elimination half-life, mean residence time, and clearance was 41 min µg ml−1 (±7.7), 44.8 min (±21.3), 13.7 min (±3.2), and 45.8 ml min−1 kg−1 (±6.5), respectively. Linear regression analysis showed a correlation between plasma concentration and infusion rate (r2=0.47). Most propofol infusion rates did not inhibit the response to noxious stimulation and rates above 11.9 mg kg−1 h−1 caused involuntary muscle contractions. Better recoveries were associated with lower propofol plasma concentrations. Propofol plasma concentration frequently increased when horses woke from anaesthesia.
Caution is warranted when propofol is used for continuous infusion due to variable kinetics, myoclonal activity, poor analgesia, and less desirable recovery quality.
A proton transfer reaction mass spectrometer (PTR-MS) was redesigned and deployed to monitor selected hydrocarbon emissions from in-use vehicles as part of the Mexico City Metropolitan Area (MCMA) ...2003 field campaign. This modified PTR-MS instrument provides the necessary time response (<2
s total cycle time) and sensitivity to monitor the rapidly changing hydrocarbon concentrations, within intercepted dilute exhaust emission plumes. Selected hydrocarbons including methanol, acetaldehyde, acetone, methyl tertiary butyl ether (MTBE), benzene and toluene were among the vehicle exhaust emission components monitored. A comparison with samples collected in canisters and analyzed by gas chromatography provides validation to the interpretation of the ion assignments and the concentrations derived using the PTR-MS. The simultaneous detection of multiple hydrocarbons in dilute vehicle exhaust plumes provides a valuable tool to study the impact of driving behavior on the exhaust gas emissions.
Atmospheric Perfluorocarbons Khalil, M. Aslam K; Rasmussen, Reinhold A; Culbertson, John A ...
Environmental science & technology,
10/2003, Letnik:
37, Številka:
19
Journal Article
Recenzirano
Collectively, man-made emissions of a few greenhouse gases may cause about the same amount of global warming as increasing carbon dioxide. Among the most potent of these non-CO2 greenhouse gases are ...the perfluorocarbons that have extraordinarily long atmospheric lifetimes of 10 000 to more than 50 000 yr. We report atmospheric concentrations over two decades, between 1978 and 1997, of the three most abundant perfluorocarbonsCF4, C2F6, and C3F8and delineate the sources that account for the present abundances and trends. We show that C2F6 and C3F8 are present at only 2.9 and 0.2 pptv, respectively. CF4 is the most abundant perfluorocarbon at 74 pptv (in 1997) of which about 40 pptv are from natural emissions, 33 pptv from aluminum manufacturing, and 1 pptv from the semiconductor industry. The increasing trend of CF4 has slowed in recent years due to the major reductions in the emission rate per ton of aluminum produced. The effect of the falling emission factor is partially offset by increased production and increasing use by the semiconductor industry.
The concentrations of CF(3)-containing compounds in archived air samples collected at Cape Meares, Oregon, from 1978 to 1997, at Point Barrow, Alaska, from 1995 to 1998, and at Palmer Station, ...Antarctica, from 1991 to 1997, were determined by high resolution gas chromatography and high resolution mass spectrometry. The CF(3)-containing compounds measured by this method and discussed here are: the perfluorinated compound, C(3)F(8) (FC 218); four perhalogenated compounds, CF(3)Cl (CFC 13), CF(3)CF(2)Cl (CFC 115), CF(3)CFCl(2) (CFC 114a), and CF(3)Br (Halon 1301); and three hydrofluorocompounds, CF(3)H (HFC 23), CF(3)CH(3) (HFC 143a), and CF(3)CH(2)F (HFC 134a). For four of these compounds, very few measurements have been previously reported. The atmospheric concentrations of all of the CF(3)-containing compounds continuously increased in time over the sample collection periods. From these data, the annual rates of emission into the atmosphere have been estimated. The emission rates fall into one of three distinct categories. The annual emission rates of C(3)F(8), CF(3)H, CF(3)CH(3), and CF(3)CH(2)F have continuously increased over the last two decades. That of CF(3)CFCl(2) has decreased continuously. Emission rates for CF(3)Cl, CF(3)CF(2)Cl, and CF(3)Br reached maximum levels in the late 1980s, and have been decreasing in the 1990s. The emission rates of C(3)F(8), CF(3)CH(3) and CF(3)CH(2)F were nearly zero 20 years ago but have increased rapidly during the last decade.
Surface plasmon resonance (SPR) imaging is a surface-sensitive spectroscopic technique for measuring interactions between unlabeled biological molecules with arrays of surface-bound species. In this ...paper, SPR imaging is used to quantitatively detect the hybridization adsorption of short (18-base) unlabeled DNA oligonucleotides at low concentration, as well as, for the first time, the hybridization adsorption of unlabeled RNA oligonucleotides and larger 16S ribosomal RNA (rRNA) isolated from the microbe Escherichia coli onto a DNA array. For the hybridization adsorption of both DNA and RNA oligonucleotides, a detection limit of 10 nM is reported; for large (1500-base) 16S rRNA molecules, concentrations as low as 2 nM are detected. The covalent attachment of thiol-DNA probes to the gold surface leads to high surface probe density (1012 molecules/cm2) and excellent probe stability that enables more than 25 cycles of hybridization and denaturing without loss in signal or specificity. Fresnel calculations are used to show that changes in percent reflectivity as measured by SPR imaging are linear with respect to surface coverage of adsorbed DNA oligonucleotides. Data from SPR imaging is used to construct a quantitative adsorption isotherm of the hybridization adsorption on a surface. DNA and RNA 18-mer oligonucleotide hybridization adsorption is found to follow a Langmuir isotherm with an adsorption coefficient of 1.8 × 107 M-1.
An improved method for the gas chromatography/mass spectrometry analysis of CF3-containing compounds in air is described. This method replaces a GS-Q porous layer open tubular (PLOT) column ...previously used with a 30 m x 0.32 mm GS-GasPro PLOT column. For this exceedingly volatile set of compounds the GS-GasPro column provides improved peak shapes, better signal-to-noise responses and no coelution of compounds. These improvements have allowed eleven CF3-containing compounds to be detected in background air, including CF4 (FC 14), C2F6 (FC 116), CF3Cl (CFC 13), CF3H (HFC 23), CF3Br (Halon 1301), C3F8 (FC 218), CF3CF2Cl (CFC 115), CF3CHF2 (HFC 125), CF3CH3 (HFC 143a), CF3CH2F (HFC 134a), and CF3CFCl2 (CFC 114a). Three of these compounds have not been previously detected in background air, to our knowledge. Quantitative determinations for each of these compounds in the background atmosphere of Montana are also reported.
During the investigation of the degradation products of 2,4,6-trinitrotoluene (TNT) using ion mobility spectrometry (IMS), 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (DCP) were ...found to have IMS responses which overlapped those of the TNT degradation products. It was observed that the Cl
− reactant ion chemistry, often used for explosives analysis, was not always successful in resolving peak overlap of analytes and interferents. It is shown here that resolution of the analytes and interferences can sometimes be achieved using only air for the formation of reactant ions, at other times through the use of Br
− as an alternative to Cl
− for producing reactant ions, and also through the promotion of adduct stability by lowering the IMS temperature.
•Aging causes alterations in the skeletal muscle phosphoproteome.•Chronic CR maintains a “youthful” phosphoproteome in skeletal muscle.•CR suppresses PKA signaling in skeletal muscle, a known ...pro-aging signaling axis.
Caloric restriction (CR) can prolong aged skeletal muscle function, yet the molecular mechanisms are not completely understood. We performed phosphoproteomic analysis on muscle from young and old mice fed an ad libitum diet, and old mice fed a CR diet. CR promoted a youthful phosphoproteomic signature, suppressing several known “pro-aging” pathways including Protein kinase A (PKA). This study validates global signaling changes in skeletal muscle during CR.
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