M E DeBakey

Publications (2)9.33 Total impact

• Article: Quantification in situ of crystalline cholesterol and calcium phosphate hydroxyapatite in human atherosclerotic plaques by solid-state magic angle spinning NMR.

  W Guo, J D Morrisett, M E DeBakey, G M Lawrie, J A Hamilton
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  ABSTRACT: Because of renewed interest in the progression, stabilization, and regression of atherosclerotic plaques, it has become important to develop methods for characterizing structural features of plaques in situ and noninvasively. We present a nondestructive method for ex vivo quantification of 2 solid-phase components of plaques: crystalline cholesterol and calcium phosphate salts. Magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of human carotid endarterectomy plaques revealed (13)C resonances of crystalline cholesterol monohydrate and a (31)P resonance of calcium phosphate hydroxyapatite (CPH). The spectra were obtained under conditions in which there was little or no interference from other chemical components and were suitable for quantification in situ of the crystalline cholesterol and CPH. Carotid atherosclerotic plaques showed a wide variation in their crystalline cholesterol content. The calculated molar ratio of liquid-crystalline cholesterol to phospholipid ranged from 1.1 to 1.7, demonstrating different capabilities of the phospholipids to reduce crystallization of cholesterol. The spectral properties of the phosphate groups in CPH in carotid plaques were identical to those of CPH in bone. (31)P MAS NMR is a simple, rapid method for quantification of calcium phosphate salts in tissue without extraction and time-consuming chemical analysis. Crystalline phases in intact atherosclerotic plaques (ex vivo) can be quantified accurately by solid-state (13)C and (31)P MAS NMR spectroscopy.
  Arteriosclerosis Thrombosis and Vascular Biology 07/2000; 20(6):1630-6. · 6.37 Impact Factor
• Article: Identification of different lipid phases and calcium phosphate deposits in human carotid artery plaques by MAS NMR spectroscopy.

  W Guo, J D Morrisett, G M Lawrie, M E DeBakey, J A Hamilton
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  ABSTRACT: Accumulation of lipids in atherosclerotic plaques causes progressive narrowing of the arterial lumen, often followed by thrombosis and ischemia. Currently several different methods, most requiring disruption of the plaque, are used to study the physical properties of lipids accumulated in plaques, and lipid composition is typically determined by chemical analysis of completely disrupted plaques. In this study, 13C magic angle spinning NMR spectroscopy (MAS NMR) was used to determine in situ the lipid composition and molecular organization of all lipid phases in human carotid artery plaques (ex vivo). Protocols were developed to observe signals from one lipid phase without interference from other phases. In addition, 31P MAS NMR detected calcification in plaques by the signals from inorganic phosphate complexed to calcium. Together, 13C and 31P MAS NMR comprise a powerful nondisruptive approach for determining the quantity and phase state of components in arterial plaques.
  Magnetic Resonance in Medicine 03/1998; 39(2):184-9. · 2.96 Impact Factor