Glutamine selective measurement

Selective Measurement of Glutamine and Asparagine in Aqueous Media by Near-Infrared Spectroscopy... 

Biologically important species, including amino acids, have unique spectral features which can be exploited to provide measurement selectivity. In the region of 5000 - 4000 cm , the major absorption contributions come from combinations of vibrational transitions for ahphatic C-H, alkene C-H, amine N-H (ionized or not) and 0-H bonds (8). Such spectral differences have been used to selectively measure structurally different compounds, such as glucose and ammonium ions (9), and glucose and glutamine (10). 

Aqueous media, glutamine and asparagine selective measurement by near-IR spectroscopy, 116-130 Ascorbic acid, role in electroenzymatic sensing of fructose using fructose dehydrogenase immobilized in self-assembled monolayer on gold, 85,8 Asparagine selective measurement in aqueous media by near-IR spectroscopy absorption bands, 118-119 apparatus, 117... 

During the culture, the concentrations of living and dead cells (by the Trypan blue exclusion method) were measured using a haemocytometer (Chapter 2, section 2.2) glucose, lactate and glutamine by enzymic methods ammonia with a selective electrode and monoclonal antibodies by ELISA assay. 

While selectivity in certain instances has been excellent (i.e., the above glutamine sensor), most tissue and bacterial electrodes are plagued by simultaneous response to several biochemical species. This is because there are often several enzymes present in a given cell which liberate the electrode-detectable product. Consequently, in situ type measurements with such... 

Decarboxylases of phenylalanine, tyrosine, and lysine and ammonia lyases of histidine, glutamine, and asparagine are also highly selective. Guilbault et al. (1988) described a potentiometric enzyme sensor for the determination of the artificial sweetener aspartame (L-aspartyl-L-phen-ylalanine methylester) based on L-aspartase (EC 4.3.1.1). The ammonia liberated in the enzyme reaction created a slope of 30 mV/decade for the enzyme-covered ammonia sensitive electrode. The specificity of the sensor was excellent however, the measuring time of 40 min per sample appears not to be acceptable. The measuring time has been decreased to about 20 min by coimmobilizing carboxypeptidase A with L-aspartase (Fatibello-Filho et al., 1988). 

Figure 5 Inhibition of [ H]-cefadroxil uptake into Caco-2 cells by stereoisomers of alanyl peptides and selected P-lactam antibiotics. In addition, influx inhibition by the dipeptides glycyl-sarcosine (Gly-Sar) and glycyl-glutamine (Gly-Gln) and the P-lactams, amoxicillin and benzylpenicillin, is presented. Uptake of 1 mM cefadroxil into Caco-2 cells was measured at apical buffer pH 6.5 for 30 min at 37°C in the absence (control) or presence of lOmM of the inhibitors. The aminopeptidase inhibitor, amasatin, was present at a concentration of 100 pM in each experiment. Values are expressed as the mean SD of 3-6 monolayers. Hatched columns ( / ) no significant inhibition open columns 50% inhibition back hatched columns ( ) 60% inhibition. (Adapted from Ref. 16.)... 

CNS (medulla, pons, spinal cord). The assay has been applied to the measurement of amino acids in segments of autopsied human spinal cord, patients dying with the clinical diagnosis of Friedreich s ataxia were found to have selectively decreased concentration of glutamate and glutamine in gray matter of lumbar spinal cord (Butterworth and Giguere, 1984). 

Asparagine and glutamine can be measured simultaneously by NIR spectroscopy with standard errors of prediction of only 0.18 mM and 0.10 mM as well as mean percent errors of 2.50% and 2.00%, respectively. This level of analysis is possible inspite of the chemical and spectroscopic similarities between these two amino acids. The successfiil measurement of these confounds suggests that NIR spectroscopy is capable of excellent selectivity which will be critical for further expanding this methodology for measuring multiple conq)onents in the complex matrices associated with bioreactors. 

A method for 3D MRSI has been demonstrated at 7T that utilises the Spectroscopic Missing Pulse - steady state free precession acquisition scheme. Modifications of previous implementations of the sequence at 3 T were required to comply with the limits of the specific absorption rate as well as to accommodate hardware limitations. The combination of two spatially selective radiofrequency pulses and a dual-band chemical shift selective radiofrequency pulse for simultaneous water and lipid suppression were used in fast 3D MRSI measurements in the brain of healthy volunteers. Signals from NAA, tCr, Cho, ml, and glutamate plus glutamine (Glx) were measured. ... 

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