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Rapid Injection (rapid + injection)

Distribution by Scientific Domains
Life Sciences50%

Selected Abstracts

Parallel separations of oligonucleotides with optically gated sample introduction on multi-channel microchips

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 1-2 2004
Hongwei Xu
Abstract With the release of the human genome sequence, there has been increasing attention given to other genetic analyses, including the detection of genetic variations and fast sequencing of multiple samples for pharmacogenomics studies. Rapid injections of samples in multiplexed separation channels by optically gated sample introduction are shown here for DNA separation. Serial separations of four amino acids are shown in less than four seconds on a microchip with four multiplexed channels. Five short oligonucleotides have also been rapidly separated in 2% LPA with four channels using this technique. In addition, multiple unique samples have been simultaneously separated and five-base resolution has been demonstrated. [source]

Integration of continuous-flow sampling with microchip electrophoresis using poly(dimethylsiloxane)-based valves in a reversibly sealed device

ELECTROPHORESIS, Issue 14 2007
Michelle W. Li
Abstract Here we describe a reversibly sealed microchip device that incorporates poly(dimethylsiloxane) (PDMS)-based valves for the rapid injection of analytes from a continuously flowing stream into a channel network for analysis with microchip electrophoresis. The microchip was reversibly sealed to a PDMS-coated glass substrate and microbore tubing was used for the introduction of gas and fluids to the microchip device. Two pneumatic valves were incorporated into the design and actuated on the order of hundreds of milliseconds, allowing analyte from a continuously flowing sampling stream to be injected into an electrophoresis separation channel. The device was characterized in terms of the valve actuation time and pushback voltage. It was also found that the addition of sodium dodecyl sulfate (SDS) to the buffer system greatly increased the reproducibility of the injection scheme and enabled the analysis of amino acids derivatized with naphthalene-2,3-dicarboxaldehyde/cyanide. Results from continuous injections of a 0.39,nL fluorescein plug into the optimized system showed that the injection process was reproducible (RSD of 0.7%, n,=,10). Studies also showed that the device was capable of monitoring off-chip changes in concentration with a device lag time of 90,s. Finally, the ability of the device to rapidly monitor on-chip concentration changes was demonstrated by continually sampling from an analyte plug that was derivatized upstream from the electrophoresis/continuous flow interface. A reversibly sealed device of this type will be useful for the continuous monitoring and analysis of processes that occur either off-chip (such as microdialysis sampling) or on-chip from other integrated functions. [source]

Brain metabolism of exogenous pyruvate

JOURNAL OF NEUROCHEMISTRY, Issue 1 2005
Susana Villa Gonzalez
Abstract Pyruvate given in large doses may be neuroprotective in stroke, but it is not known to what degree the brain metabolizes pyruvate. Intravenous injection of [3- 13C]pyruvate led to dose-dependent labelling of cerebral metabolites so that at 5 min after injection of 18 mmoles [3- 13C]pyruvate/kg (2 g sodium pyruvate/kg), approximately 20% of brain glutamate and GABA were labelled, as could be detected by 13C nuclear magnetic resonance spectrometry ex vivo. Pyruvate, 9 mmoles/kg, was equivalent to glucose, 9 mmoles/kg, as a substrate for cerebral tricarboxylic acid (TCA) cycle activity. Inhibition of the glial TCA cycle with fluoroacetate did not affect formation of [4- 13C]glutamate or [2- 13C]GABA from [3- 13C]pyruvate, but reduced formation of [4- 13C]glutamine by 50%, indicating predominantly neuronal metabolism of exogenous pyruvate. Extensive formation of [3- 13C]lactate from [2- 13C]pyruvate demonstrated reversible carboxylation of pyruvate to malate and equilibration with fumarate, presumably in neurones, but anaplerotic formation of TCA cycle intermediates from exogenous pyruvate could not be detected. Too rapid injection of large amounts of pyruvate led to seizure activity, respiratory arrest and death. We conclude that exogenous pyruvate is an excellent energy substrate for neurones in vivo, but that care must be taken to avoid the seizure-inducing effect of pyruvate given in large doses. [source]

Pressures generated in vitro during Stabident intraosseous injections

INTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2005
J. M. Whitworth
Abstract Aim, To test the hypothesis that the Stabident intraosseous injection is a potentially high-pressure technique, which carries serious risks of anaesthetic cartridge failure. Methodology, A standard Astra dental syringe was modified to measure the internal pressure of local anaesthetic cartridges during injection. Intra-cartridge pressures were measured at 1 s intervals during slow (approximately 15 s) and rapid (<10 s) injections of 2% Xylocaine with 1 : 80 000 adrenaline (0.25 cartridge volumes) into air (no tissue resistance), or into freshly prepared Stabident perforation sites in the anterior mandible of freshly culled young and old sheep (against tissue resistance). Each injection was repeated 10 times over 3 days. Absolute maximum pressures generated by each category of injection, mean pressures at 1 s intervals in each series of injections, and standard deviations were calculated. Curves of mean maximum intra-cartridge pressure development with time were plotted for slow and rapid injections, and one-way anova (P < 0.05) conducted to determine significant differences between categories of injection. Results, Pressures created when injecting into air were less than those needed to inject into tissue (P < 0.001). Fast injection produced greater intra-cartridge pressures than slow delivery (P < 0.05). Injection pressures rose more quickly and to higher levels in small, young sheep mandibles than in larger, old sheep mandibles. The absolute maximum intra-cartridge pressure developed during the study was 3.31 MPa which is less than that needed to fracture glass cartridges. Conclusions, Stabident intraosseous injection conducted in accordance with the manufacturer's instructions does not present a serious risk of dangerous pressure build-up in local anaesthetic cartridges. [source]