Biomarker Identification

Identification of the metabolic biomarkers of a pathological situation can involve the application of the full range of analytical physical chemistry techniques, including mass spectrometry and NMR spectroscopy. The NMR spectra of urine and other biofluids, although they are very complex, allow many resonances to be assigned directly based on their chemical shifts, signal multiplicities, and by adding authentic material, and further information can be obtained by using spectral editing techniques.

Two-dimensional NMR spectroscopy can be useful for increasing signal dispersion and for identification of bio-markers. These include the 1H-1H 2-D J-resolved experiment, which yields information on the multiplicity and coupling patterns of resonances. Other 2-D experiments known as COSY and TOCSY provide 1H-1H

spin-spin coupling connectivities, thus giving information on which hydrogens in a molecule are close in chemical bond terms. Use of other types of nuclei, such as naturally abundant 13C, 15N, or 31P, can help assign NMR peaks, and here 2-D correlation NMR experiments can also be obtained by the use of NMR pulse sequences that allow detection at the more abundant and sensitive 1H nucleus. For example, these yield both 1H and 13C NMR chemical shifts of CH, CH2, and CH3 groups, useful again for identification purposes. There is also a sequence that allows correlation of protons to quaternary carbons.

It is also possible to separate substances of interest from a biofluid sample using solid-phase extraction or HPLC, and directly coupled chromatography-NMR spec-troscopy methods can be used. The most powerful is HPLC-NMR-MS.[8] Other MS-based methods include MSn for identification of fragment ions and FT-MS or TOF-MS for accurate mass measurement and derivation of molecular formulae.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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