MAGNETIC RESONANCE IN MEDICINE zyxwvutsrqp 21,222-232 zyxwvu ( I99 I ) A Lineshape Fitting Model for 'H NMR Spectra of Human Blood Plasma Y. HILTUNEN, *,? M. ALA-KORPELA, *,I J. JOKISAARI, * S. ESKELINEN,+ K. KIVINIITTY,+ M. SAVOLAINEN,~ AND Y. A. KESANIEMI$ * zyxwvutsrq Department of Physics, University of Oulu, SF-905 70 Oulu, Finland; $Department zyx o f Biomedical Physics, University ofol4h4, SF-90220 Oulu, Finland; zyxwv 0 Department of Internal Medicine. University of Oulu, SF-90220 Oulu, Finland; and t NMR Research Group, Department o f Chemistry, University o f Kuopio, zyxwvut SF- 7021 I Kuopio, Finland Received July 18, 1990 A lineshape fitting model was constructed for classifying the overlapping information in the 'H NMR spectrum of human blood plasma. A reliable assignment of the overlapping fatty acid ( -CH2-)" and -CH3 resonances of the various lipoproteins (VLDL, very low density lipoprotein; LDL, low density lipoprotein; HDL high density lipoprotein) is in- troduced, and for the first time detailed characteristics (chemical shifts, half linewidths, and relative intensities) of the individual lipoprotein components were obtained directly from the whole plasma spectrum. This was achieved by combining the constructed lineshape fitting model and the proper 400 MHz proton NMR measurements from blood plasma of a healthy donor, from fractions of the different lipoproteins, and from plasma samples in which the lipoprotein fractions were separately added. The results suggest fair promise of future applications of the rapid and easy NMR analysis of lipoprotein distribution in various research and clinical situations. 0 199 I Academic Press, Inc. INTRODUCTION Biological NMR spectroscopy is a common interest and area of cooperation of many branches of science. It has developed rapidly in recent years and one of the main spurs for further investigations is the possibility of important, easy, and unique clinical applications. Although biological samples contain many NMR detectable iso- topes, proton is overwhelmingly the most frequent one and offers a high sensitivity. Thus PMR enables a large number of various studies on different phenomena to be carried out but reveals also balancing difficulties, such as an intense water resonance, a complicated background, and particularly a marked overlap of signals arising from the CH, CH2, and CH3portions of the macromolecules. Studies on the (-CH,-), and -CH3 signals of the lipoproteins in human blood plasma are a good example of the actual overlap problem ( 1-4). Different methods have been applied to the analysis of NMR spectra. In simple cases the chemical shifts and intensities are obtained automatically using peak picking routines in the frequency domain spectrum. However, when the object of interest becomes more complicated, an overlap of the signals occurs and the simplicity is lost, attention has to be turned toward more sophisticated methods. The main choice to be made is whether to work with the FID signal or with the more visual frequency domain spectrum. If operating with the FID is preferred, there exist powerful tools, 'To whom correspondence should be addressed. 0740-3194/91 $3.00 222 Copyright 0 1991 by Academic Press, Inc. All rights of reproduction in any form reserved.