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Plasma high density lipoproteins (HDL) are a negative risk factor for atherosclerosis. Increased HDL is sometimes clustered in families, but a genetic basis has never been clearly documented. The plasma cholesteryl ester transfer protein (CETP) catalyses the transfer of cholesteryl ester from HDL to other lipoproteins and therefore might influence HDL levels. Using monoclonal antibodies, we show that CETP is absent in two Japanese siblings who have markedly increased and enlarged HDL. Furthermore, they are homozygous for a point mutation in the 5'-splice donor site of intron 14 of the gene for CETP, a change that is incompatible with normal splicing of pre-messenger RNA. The results indicate that the family has an inherited deficiency of CETP due to a gene splicing defect, and illustrate the key role that CETP has in human HDL metabolism.

Plasma net cholesteryl ester (CE) transfer and optimum cholesteryl ester transfer protein (CETP) activity were determined in primary hypertriglyceridemic (a = 11) and normolipidemic (a = 15) individuals. The hypertriglyceridemic group demonstrated threefold greater net CE transfer leading to enhanced accumulation of CE in VLDL. This increased net transfer was not accompanied by a change in CETP activity. In normolipidemia, but not in hypertriglyceridemia, net CE transfer correlated with VLDL triglyceride (r = 0.92, P < 0.001). In contrast, net CE transfer in hypertriglyceridemia, but not in normolipidemia, correlated with CETP activity (r = 0.73, P < 0.01). Correction of hypertriglyceridemia with bezafibrate reduced net CE transfer towards normal and restored the correlation with VLDL triglyceride (r = 0.90, P < 0.005) while suppressing the correlation with CETP activity. That net CE transfer depends on VLDL concentration was confirmed by an increase ofnet CE transfer in normolipidemic plasma supplemented with purified VLDL. Supplementation of purified CETP to normolipidemic plasma did not stimulate net CE transfer. In contrast, net CE transfer was enhanced by addition of CETP to both plasma supplemented with VLDL and hypertriglyceridemic plasma.

Cholesteryl ester transfer protein (CETP) mediates an important pathway for reverse cholesterol transport. Concentrations of CETP in fasting plasma were measured by radioimmunoassay in two different groups of hyperlipoproteinemic subjects. Plasma CETP concentrations measured by radioimmunoassay correlated closely with cholesterol ester transfer activity in normal plasma (r=0.86). In the first group of 58 patients, plasma CETP concentrations were significantly increased, as compared with those in 79 normal subjects and in hypercholesterolemic (+26%) and combined hyperlipoproteinemic (+25%) subjects but were not altered in moderately hypertriglyceridemic subjects. Marked elevations in plasma CETP levels were documented in patients with dysbetalipoproteinemia (+68%) and severe chylomicronemia (+85%). Similar results were obtained in a second population of 50 hyperlipoproteinemic subjects. Significant correlations were found between plasma CETP levels and total cholesterol (r=0.52), very low density lipoprotein (VLDL) cholesterol (r=0.63), and apolipoprotein E concentration (r=0.40). Correction of the lipoprotein phenotype by dietary means resulted in significant reductions in plasma CETP concentrations in patients with chylomicronemia and dysbetalipoproteinemia. In these subjects, plasma high density lipoprotein cholesterol concentrations increased as CETP decreased. These studies indicate that CETP levels increase in association with enhanced peripheral cholesterol transport via low density lipoprotein, /3-VLDL, or chylomicron remnants. (Arteriosclerosis and Thrombosis 1991;ll:797-804) E arly studies by Rehnborg and Nichols 1 and Nichols and Smith 2 demonstrated that on incubation of normolipemic plasma, cholesteryl ester (CE) increased in very low density lipoprotein (VLDL), whereas triglyceride (TG) concentration decreased in VLDL but increased in high density lipoprotein (HDL) and low density lipoprotein (LDL). These experiments were the first to document CE transfer between lipoproteins, a phenomenon that was further clarified by the demonstra- tion by Zilversmit et al 3 that the d>1.21 g/ml fraction contained a protein that catalyzed CE transfer between lipoproteins, a protein that is now identified as cholesteryl ester transfer protein (CETP). More recently, two research groups have purified and characterized CETP, which is a very hydrophobic protein with a molecular size of M r 74,000, 45 in agreement with the data derived from the cloning and sequencing of the cDNA encoding for CETP. 6 While CETP mediates only the exchange of CEs between HDL and LDL, 7 it does promote net transfer of CEs from HDL to VLDL and chylomicrons. 8 This specificity of the transfer reaction makes it a major pathway for reverse cholesterol transport in many mammalian species. However, the significance of plasma levels of CETP in atherosclerosis must be considered in terms of the two facets of the CETPmediated system -factors facilitating the accumulation of HDL CE (secretion of nascent HDL, its interaction with peripheral cells...

Increases in choline containing metabolites have been associated with a number of disorders, including malignant cell growth. In this study, high resolution magic angle spinning 1 H nuclear magnetic resonance spectroscopy was employed to monitor metabolite changes during cell transfection, and an increase in phosphocholine was detected. This increase appears to be correlated with cell membrane disruption associated with the insertion of plasmid DNA into cells, since the level of phosphocholine in mock transfected cells was comparable to that of control cells. These data suggest choline containing metabolite changes detected in vivo using magnetic resonance spectroscopy relate to cell membrane disruption. ß

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. An integrated reverse functional genomic and metabolic approach to understanding orotic acid-induced fatty liver. Physiol Genomics 17: 140-149, 2004. First published January 27, 2004 10.1152/physiolgenomics.00158.2003.-In functional genomics, DNA microarrays for gene expression profiling are increasingly being used to provide insights into biological function or pathology. To better understand the significance of the multiple transcriptional changes across a time period, the temporal changes in phenotype must be described. Orotic acid-induced fatty liver disease was investigated at the transcriptional and metabolic levels using microarrays and metabolic profiling in two strains of rats. Highresolution 1 H-NMR spectroscopic analysis of liver tissue indicated that Kyoto rats compared with Wistar rats are predisposed to the insult. Metabolite analysis and gene expression profiling following orotic acid treatment identified perturbed metabolic pathways, including those involved in fatty acid, triglyceride, and phospholipid synthesis, ␤-oxidation, altered nucleotide, methyl donor, and carbohydrate metabolism, and stress responses. Multivariate analysis and statistical bootstrapping were used to investigate co-responses with transcripts involved in metabolism and stress responses. This reverse functional genomic strategy highlighted the relationship between changes in the transcription of stearoyl-CoA desaturase 1 and those of other lipid-related transcripts with changes in NMR-derived lipid profiles. The results suggest that the integration of 1 H-NMR and gene expression data sets represents a robust method for identifying a focused line of research in a complex system. transcriptomics; metabolomics/metabonomics; DNA microarray; system biology; bioinformatics DNA MICROARRAYS are increasingly being used in functional genomic strategies for understanding gene function and pathology (5,26,27). To fully use the information generated by this technology, it is necessary to have a description of the changing phenotype so that gene expression can be understood in a biological context. To achieve this, there is recognition that the large-scale analysis of metabolites, as by proton nuclear magnetic resonance spectroscopy ( 1 H-NMR) or mass spectrometry, provides a final conduit to link differential mRNA responses with specific metabolic pathways by defining a metabolic phenotype (10,12,24). The analysis of multivariate data sets that are generated within these different tiers of biological organization may potentially yield critical information about the mechanisms involved in biological transitions. However, enhanced understanding of complex biological systems requires the development of strategies for integration of the different tiers, which link information derived at each level in a systematic way (24, 34). In particular in complex biological systems where large data sets will be the routine, there is a need to integrate the different functional genomic approaches, taking into consideration the scaling and correlation ...

Using social pressure to mobilize voters has generated impressive increases in turnout (Gerber et al. Am Polit Sci Rev 102:33-48, 2008). However, voters may have negative reactions to social pressure treatments that reduce their effectiveness. Social psychologists have observed this 'reactance' to persuasive pressure about other behavior, but it has been overlooked in voter mobilization. Using a large-scale field experiment, we find treatments designed to reduce reactance are just as effective as heavy-handed social pressure treatments in mobilizing voters. The success of gentler social pressure treatments should make the use of social pressure more palatable to voter mobilization organizations.