Glucose spectroscopy

Biosensors (qv) and DNA probes ate relatively new to the field of diagnostic reagents. Additionally, a neat-infrared (nit) monitoring method (see Infrared TECHNOLOGY AND RAMAN SPECTROSCOPY), a teagenfless, noninvasive system, is under investigation. However, prospects for a nit detection method for glucose and other analytes ate uncertain. 

Grootveld, M.C., Henderson, E.B., Farrell, A., Blake, D.R. and Parkes, H.G. (1991). Oxidative damage to hyaluronate and glucose in synovial fluid during exercise of the inflamed rheumatoid joint. Detection of abnormal low-molecular mass metabolites by proton nmr spectroscopy. Biochem. J. 273, 459-467. 

Glucose isomerase catalyzes the conversion of D-glucose to D-fructose and has also been used extensively on an industrial scale.1184 Some, but not all, enzymes of this family require Co specifically, while others can function with other divalent ions. Environmental and health issues limit the concentrations of Co in culture media during D-fructose production and other metal ions are being sought as substitutes. Although the active site structure remains unknown, EXAFS, optical and EPR spectroscopy has suggest a low-spin divalent Co ion, bound by N and O-donors only (no S-donors). 

Measurements in living things, e.g. patients, is occasionally done by sampling in a non-invasive way. Because no standard patients are available which can be selected for calibration, another principle of calibration must be applied, e.g., by a reference method that measures parallel to the actual measuring method. So, the calibration consists in a comparison of the measured results with that of the reference method which are considered to be true (that have been validated beforehand). An example of a reference calibration is represented by non-invasive blood glucose determination by means of NIR spectroscopy (Muller et al. [1997] Fischbacher et al. [1997] Danzer et al. [1998], see Sect. 6.2.6). 

Intensified metabolic control, especially in case of diabetes, demands minimal-invasive or non-invasive methods of analytical measurement. For this goal, a method has been developed to measure the blood glucose content in vivo, in direct contact with the skin, by means of diffuse reflection near infrared (NIR) spectroscopy on the basis of multivariate calibration and neural networks (Muller et al. [1997] Fischbacher et al. [1997] Danzer et al. [1998]). Because no patients with any standard blood glucose value are available in principle, a method of indirect calibration has... 

The latter applies to NIR spectroscopy used for the non-invasive determination of blood glucose by means of a fibre-optical measuring-head (Jagemann et al. [1995] Muller et al. [1997] Danzer et al. [1998]). In addition to the weak overtone and combination bands resulting from glucose, strongly disturbing absorption of water, that is the main component... 

Danzer K, Fischbacher C, Jagemann K-U, Reichelt KJ (1998) Near-infrared diffuse reflection spectroscopy for non-invasive blood-glucose monitoring. LEOS Newslett 12(2) 9... 

Jagemann K-U, Fischbacher C, Danzer K, Muller UA, Mertes B (1995) Application of near-infrared spectroscopy for non-invasive determination of blood/tissue glucose using neural networks. Z Physikal Chem 191 179... 

Mtlller UA, Mertes B, Fischbacher C, Jagemann K-U, Danzer K (1997) Non-invasive blood glucose monitoring by means of near infrared spectroscopy methods for Improving the reliability of the calibration models. Int J Artific Organs 20 285... 

Malin S.F., Ruchti T.L., Blank T.B., Thennadil S.N., Monfre S.L., Noninvasive prediction of glucose by near-infrared diffuse reflectance spectroscopy, Clin. Chem. 1999 45 (9) 1651-1658. 

On the other hand, 13C-NMR spectroscopy not only allows the simultaneous and separate detection of signals from different compounds, but also within different atoms in a given molecule. For example, carbon-13 from glucose labeled at the Cl (or C6) position is incorporated via the PDH reaction into the C2 of acetyl-CoA, and subsequently into the C4 of a-ketoglutarate (Fig. 31-9), which labels the... 

Fitzpatrick, S. M., Hetherington, H. P, Behar, K. L. etal. The flux from glucose to glutamate in the rat brain in vivo as determined by H-observed, 13C-edited NMR spectroscopy. /. Cereb. Blood Flow Metab. 2 170-179,1990. 

Gruetter, R., Novotny, E. J., Boulware, S. D. etal. Localized 13C NMR spectroscopy of amino acid labeling from [ 1—13C] D-glucose in the human brain. /. Neurochem. 63 1377-1385, 1994. 

Waagepetersen, H., Bakken, I. J., Larsson, O. M. etal. Comparison of lactate and glucose metabolism in cultured neocortical neurons using 13C NMR spectroscopy. Dev. Neurosci. 20 310-321,1998. 

Potter and co-workers 301) determined reducing sugars in plant materials by reducing copper(II) in alkaline solution to insoluble cuprous oxide and then measuring the excess copper in the filtrate. Mitschell248) conducted further studies on this method. Christian and Feldman 19) have described general procedures for the indirect determination of glucose and of protein. It is anticipated that in the future, we will see many more applications of atomic absorption spectroscopy to the indirect determination of nonmetals. 

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