Detection of in vivo hepatitis B virus surface antigen mutations-A comparison of four routine screening assays.

An important requirement for a state-of-the-art hepatitis B surface antigen (HBsAg) screening assay is reliable detection of mutated HBsAg. Currently, there is a striking shortage of data regarding the detection rates of in vivo HBsAg mutations for these clinically important assays. Therefore, we compared the detection rates of four commercial HBsAg screening assays using a global cohort of 1553 patients from four continents with known HBV genotypes. These samples, which represent the broadest spectrum of known and novel HBsAg major hydrophilic region (MHR) mutations to date, were analyzed for the presence of HBsAg using the Roche Elecsys® HBsAg II Qualitative, Siemens ADVIA Centaur XP HBsAg II, Abbott Architect HBsAg Qualitative II and DiaSorin Liaison® HBsAg Qualitative assays, respectively. Of the 1553 samples, 1391 samples could be sequenced; of these, 1013 (72.8%) carried at least one of the 345 currently known amino acid substitutions (distinct HBsAg mutation) in the HBsAg MHR. All 1553 patient samples were positive for HBsAg using the Elecsys® HBsAg II Qual assay, with a sensitivity (95% confidence interval) of 99.94% (99.64%-100%), followed by the Abbott Architect 99.81% (99.44%-99.96%), Siemens ADVIA 99.81% (99.44%-99.96%) and DiaSorin Liaison® 99.36% (98.82%-99.69%) assays, respectively. Our results indicate that the Elecsys® HBsAg II Qual assay exhibits the highest sensitivity among the commercial HBsAg screening assays, and demonstrate that its capacity to detect HBV infection is not compromised by HBsAg MHR mutants.

Transport of lipids from golgi to plasma membrane is defective in tangier disease patients and Abc1-deficient mice.

Mutations in the gene encoding ATP-binding cassette transporter 1 ( ABC1) have been reported in Tangier disease (TD), an autosomal recessive disorder that is characterized by almost complete absence of plasma high-density lipoprotein (HDL), deposition of cholesteryl esters in the reticulo-endothelial system (RES) and aberrant cellular lipid trafficking. We demonstrate here that mice with a targeted inactivation of Abc1 display morphologic abnormalities and perturbations in their lipoprotein metabolism concordant with TD. ABC1 is expressed on the plasma membrane and the Golgi complex, mediates apo-AI associated export of cholesterol and phospholipids from the cell, and is regulated by cholesterol flux. Structural and functional abnormalities in caveolar processing and the trans-Golgi secretory pathway of cells lacking functional ABC1 indicate that lipid export processes involving vesicular budding between the Golgi and the plasma membrane are severely disturbed.

The gene encoding ATP-binding cassette transporter 1 is mutated in Tangier disease.

Tangier disease (TD) is an autosomal recessive disorder of lipid metabolism. It is characterized by absence of plasma high-density lipoprotein (HDL) and deposition of cholesteryl esters in the reticulo-endothelial system with splenomegaly and enlargement of tonsils and lymph nodes. Although low HDL cholesterol is associated with an increased risk for coronary artery disease, this condition is not consistently found in TD pedigrees. Metabolic studies in TD patients have revealed a rapid catabolism of HDL and its precursors. In contrast to normal mononuclear phagocytes (MNP), MNP from TD individuals degrade internalized HDL in unusual lysosomes, indicating a defect in cellular lipid metabolism. HDL-mediated cholesterol efflux and intracellular lipid trafficking and turnover are abnormal in TD fibroblasts, which have a reduced in vitro growth rate. The TD locus has been mapped to chromosome 9q31. Here we present evidence that TD is caused by mutations in ABC1, encoding a member of the ATP-binding cassette (ABC) transporter family, located on chromosome 9q22-31. We have analysed five kindreds with TD and identified seven different mutations, including three that are expected to impair the function of the gene product. The identification of ABC1 as the TD locus has implications for the understanding of cellular HDL metabolism and reverse cholesterol transport, and its association with premature cardiovascular disease.

Pulmonary embolism: CT signs and cardiac biomarkers for predicting right ventricular dysfunction.

The aim of this study was to prospectively evaluate the accuracy of quantitative cardiac computed tomography (CT) parameters and two cardiac biomarkers (N-terminal-pro-brain natriuretic peptide (NT-pro-BNP) and troponin I), alone and in combination, for predicting right ventricular dysfunction (RVD) in patients with acute pulmonary embolism. 557 consecutive patients with suspected pulmonary embolism underwent pulmonary CT angiography. Patients with pulmonary embolism also underwent echocardiography and NT-pro-BNP/troponin I serum level measurements. Three different CT measurements were obtained (right ventricular (RV)/left ventricular (LV)(axial), RV/LV(4-CH) and RV/LV(volume)). CT measurements and NT-pro-BNP/troponin I serum levels were correlated with RVD at echocardiography. 77 patients with RVD showed significantly higher RV/LV ratios and NT-pro-BNP/troponin I levels compared to those without RVD (RV/LV(axial) 1.68 ± 0.84 versus 1.00 ± 0.21; RV/LV(4-CH) 1.52 ± 0.45 versus 1.01 ± 0.21; RV/LV(volume) 1.97 ± 0.53 versus 1.07 ± 0.52; serum NT-pro-BNP 6,372 ± 2,319 versus 1,032 ± 1,559 ng · L(-1); troponin I 0.18 ± 0.41 versus 0.06 ± 0.18 g · L(-1)). The area under the curve for the detection of RVD of RV/LV(axial), RV/LV(4-CH), RV/LV(volume), NT-pro-BNP and troponin I were 0.84, 0.87, 0.93, 0.83 and 0.70 respectively. The combination of biomarkers and RV/LV(volume) increased the AUC to 0.95 (RV/LV(volume) with NT-pro-BNP) and 0.93 (RV/LV(volume) with troponin I). RV/LV(volume) is the most accurate CT parameter for identifying patients with RVD. A combination of RV/LV(volume) with NT-pro-BNP or troponin I measurements improves the diagnostic accuracy of either test alone.

Endothelial cells of hematopoietic origin make a significant contribution to adult blood vessel formation.

Granulation tissue formation is an example of new tissue development in an adult. Its rich vascular network has been thought to derive via angiogenic sprouting and extension of preexisting vessels from the surrounding tissue. The possibility that circulating cells of hematopoietic origin can differentiate into vascular endothelial cells (ECs) in areas of vascular remodeling has recently gained credibility. However, no quantitative data have placed the magnitude of this contribution into a physiological perspective. We have used hematopoietic chimeras to determine that 0.2% to 1.4% of ECs in vessels in control tissues derived from hematopoietic progenitors during the 4 months after irradiation and hematopoietic recovery. By contrast, 8.3% to 11.2% of ECs in vessels that developed in sponge-induced granulation tissue during 1 month derived from circulating hematopoietic progenitors. This recruitment of circulating progenitors to newly forming vessels would be difficult to observe in standard histological studies, but it is large enough to be encouraging for attempts to manipulate this contribution for therapeutic gain.

A comparison of the diagnostic utility of the sFlt-1/PlGF ratio versus PlGF alone for the detection of preeclampsia/HELLP syndrome.

OBJECTIVE: The Elecsys(®) immunoassay sFlt-1/PlGF ratio and the Triage(®) PlGF assay were compared (in a prospective, multicenter, case-control study) for diagnosis of preeclampsia/hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome. METHODS: Women in European perinatal care centers with singleton pregnancies were enrolled: 178 cases had confirmed preeclampsia and 391 controls had normal outcome. Patients in the preeclampsia/HELLP syndrome group were matched pairwise by gestational week to healthy controls (1:2). Maternal blood samples were analyzed using (a) fully automated Elecsys PlGF and Elecsys sFlt-1 immunoassays with two cutoffs (early-onset [<34 weeks] ≤33, ≥85; late-onset [≥34 weeks] ≤33, ≥110), and (b) Triage PlGF immunoassay (single cutoff). Diagnostic performance and utility were assessed. RESULTS: Respectively, 83 and 95 women had early-onset or late-onset preeclampsia/HELLP syndrome. The overall diagnostic performance of the Elecsys immunoassay sFlt-1/PlGF ratio (area under the curve [AUC] 0.941) was higher than for Triage PlGF (AUC 0.917). The Elecsys immunoassay sFlt-1/PlGF ratio sensitivity and specificity was: 94.0% (95% confidence interval [CI] 86.5-98.0) and 99.4% (95% CI: 96.8-99.9) for early-onset preeclampsia; and 89.5% (95% CI: 81.5-94.8) and 95.4% (95% CI: 91.7-97.8) for late-onset preeclampsia. The Triage assay sensitivity and specificity was: 96.4% (95% CI: 89.8-99.3) and 88.5% (95% CI: 82.8-92.8) (early-onset); and 90.5% (95% CI: 83-96) and 64.5% (95% CI: 57.8-70.9) (late onset). CONCLUSIONS: The fully automated Elecsys immunoassay sFlt-1/PlGF ratio provides improved diagnostic utility over the Triage PlGF assay with improved specificity for the clinical management of pregnant women with suspected preeclampsia/HELLP syndrome.

IGF-1, PDGF and CD18 are adherence-responsive genes: regulation during monocyte differentiation.

Unstimulated mononuclear cells express IGF-1, PDGF-A and PDGF-B mRNA, but not a number of other genes coding for growth factors or cytokines, as we demonstrated previously. The main focus of the present investigation was to compare gene expression of mononuclear cells unstimulated in suspension with gene expression of monocytes stimulated by adherence. mRNA levels of IGF-1-A and -B, PDGF-A, -B, PD-ECGF, basic FGF, acidic FGF, TGF-alpha, TGF-beta 1, and IGF-2 were sought for and quantified with our sensitive RT-PCR method (3n-PCR). The respective mRNAs of basic FGF, acidic FGF, TGF-alpha and IGF-2 were not detected, independent of the culture conditions. In suspension culture, mRNA levels of IGF-1A and -B, PDGF-A, -B, and CD18 remained unchanged. Monocyte adherence regulated IGF-1A, PDGF-A, and -B mRNA levels. In parallel, mRNA levels of the monocyte adhesion molecule CD18 increased rapidly (4.5-fold). In contrast, independent of the presence of an adherence stimulus, the mRNAs for the cytoskeletal structure protein beta-actin and PD-ECGF remained constant, whereas mRNA for growth factors TGF-beta 1 and IGF-1B, respectively, was increased. Thus, monocyte adherence selectively regulates IGF-1, PDGF-A, PDGF-B and CD18 mRNAs (adherence-responsive genes) in a coordinated manner. This led us to identify two novel consensus elements within their respective functional promoters. Both motifs, an 11 bp purine-rich sequence and a 13 bp pyrimidine-rich segment, respectively, are absent from the genes that were not specifically activated by adherence. The identified elements are potential binding sites for transcription factors that may define a common basis for the regulation of the adherence-responsive genes IGF-1A, PDGF-A, PDGF-B and CD18.

Dietary n-3 fatty acids accelerate catabolism of leukotriene B4 in human granulocytes.

Addition of n-3 fatty acids to a human diet for more than 3 weeks lowers levels of the powerful proinflammatory compound, leukotriene (LT) B4. This can be shown ex vivo after stimulation of human granulocytes with ionophore A23187. In a controlled, randomized, observer-blind study in 14 human volunteers, we investigated the effect of adding 7 g/day of a 85% n-3 fatty acid concentrate to the diet of 7 volunteers (7 served as controls). Levels of LTB4, 20-OH-LTB4, 20-COOH-LTB4 as well as LTB5, 20-OH-LTB5 and 20-COOH-LTB5 were measured by high-pressure liquid chromatography (HPLC) after stimulation and extraction of a platelet-free granulocyte preparation (92% neutrophils). LTB5 and 20-COOH-LTB5 were only detected during n-3 fatty acids, when 20-OH-LTB5 increased from trace amounts to substantial quantities. Importantly, levels of catabolites of LTB4, i.e., 20-OH-LTB4 and 20-COOH-LTB4 were not significantly altered throughout the study. However, the level of LTB4 itself was reduced dramatically after 6 weeks (less so after 1 week) of dietary n-3 fatty acid administration. These data demonstrate that during dietary n-3 fatty acids levels of LTB4 are lowered by a combination of accelerated catabolism and diminished LTB4 generation. This newly observed mechanism of increased LT catabolism may be mediated via induction of peroxisomal enzymes catabolizing leukotrienes B.

ABC transporters and cholesterol metabolism.

ATP-binding cassette (ABC) proteins form a group of highly conserved cellular transmembrane transporters. Studies over the past year have implicated ABC transporters in cellular lipid trafficking processes. This notion has recently been confirmed and extended by the finding that the ABC transporter ABCA1 is a key regulator of high-density lipoprotein (HDL) metabolism and macrophage targeting to the RES or the vascular wall. Expression of a large number of ABC transporters in monocytes/macrophages and their regulation by cholesterol flux render these transporter molecules potentially critical players in chronic inflammatory diseases such as atherosclerosis.

Thrombosis and inflammation as multicellular processes: significance of cell-cell interactions.

Platelet activation as a result of vascular injury provokes endothelial cells to respond in a manner which limits or reverses the occlusive consequences of platelet accumulation. If the agonistic forces are strong, platelet accumulation is irreversible. In vitro data from our laboratory have repeatedly demonstrated that platelets become unresponsive to all agonists when in proximity to endothelial cells. This unresponsiveness is due to at least three separate endothelial "thromboregulatory" systems: eicosanoids, endothelium-derived relaxing factor (EDRF/NO), and most importantly an endothelial cell ecto-nucleotidase which metabolizes released platelet adenosine diphosphate (ADP) with consequent restoration of platelets to the resting state. This nucleotidase is operative in the complete absence of EDRF/NO and eicosanoids, indicating that the latter two are dispensable thromboregulators. We have solubilized the human endothelial cell ectoADPase, as well as that from placental tissue. Candidate proteins from a purified ADPase fraction are now being studied in further detail. An understanding of the molecular biology of the ADPase gene may lead to development of therapeutic agents such as soluble forms of the enzyme as well as approaches toward up-regulation of ectoADPase activity. This could result in "early thromboregulation", i.e. prevention and/or reversal of platelet accumulation at sites of vascular damage via immediate metabolic removal of the prime platelet agonist-ADP.

Elastosis perforans serpiginosa-like pseudoxanthoma elasticum in a child with severe Moya Moya disease.

A 2-year-old girl with Moya Moya disease who had relapsing cerebrovascular strokes presented with loose skin folds, 'chicken' skin appearance and perforating elastosis serpiginosa-like lesions in the genitocrural region. Histologically, calcified material perforating the epidermis and adjacent short curled and mineralized elastic fibres suggested a variant of pseudoxanthoma elasticum (PXE). As PXE is known to be caused by various mutations in the transmembrane transporter ABCC6 gene, we hypothesized that a novel ABCC6 mutation may underlie this unique combination of PXE and elastopathic vascular damage. Therefore, the complete ABCC6 coding region of the patient and her parents was screened for genetic alterations. No bona fide disease-causing mutation of ABCC6 could be found in the child and in her parents. However, two novel allelic amino acid substitutions (Arg1273Lys and Glu1293Lys; exon 27) were found in the girl and her father, localized in close proximity to the region that codes for the functionally critical second nucleotide-binding fold of ABCC6. Although a causal involvement of these amino acid substitutions could not be proven based on this study, both heterozygote substitutions may possibly have interacted with other undetected recessive maternal ABCC6 changes in the child. To the best of our knowledge, this is the first report of an association between early-onset PXE and severe Moya Moya syndrome possibly related to ABCC6 changes.

ABCA2: a candidate regulator of neural transmembrane lipid transport.

Studies in the past years have implicated multispan transmembrane transport molecules of the ATP binding cassette (ABC) transporter family in cellular lipid export processes. The prototypic ABC transporter ABCA1 has recently been demonstrated to act as a major facilitator of cellular cholesterol and phospholipid export. Moreover, the transporter ABCA4 (ABCR) plays a pivotal role in retinaldehyde processing, and ABCA3 has recently implicated in lung surfactant processing. These pioneering observations have directed considerable attention to the A subfamily of ABC proteins. ABCA2 is the codefining member of the ABC A-transporter subclass. Although known for some time, it was not until recently that its complete molecular structure was established. Unlike other ABC A-subfamily members, ABCA2 is predominantly expressed in the brain and neural tissues. The unique expression profile together with available structural data suggest roles for this largest known ABC protein in neural transmembrane lipid export.

Isolation of human promoter regions by Alu repeat consensus-based polymerase chain reaction.

Knowledge of the promoter structure is critical for an understanding of the regulation of genes. We demonstrate by analysis of 405 human genes that human promoter regions are flanked by upstream Alu repeat elements, typically at a distance of 0.5-5 kb from their protein-coding areas. We identified common Alu repeat consensus sequences (ARC) among the different members of the Alu subfamilies that can be used as universal anchor sites for polymerase chain reaction (PCR) amplification. Utilizing ARC-specific primers and oligonucleotides specific for the 5' end of a selected target gene, we show that sequences spanning unknown human gene promoter regions can be directly amplified by PCR from genomic DNA. This novel technique, termed ARC-PCR, allowed us to characterize the proximal promoters of the human LTA4 hydrolase and SPARC genes, each within 1 day.

Genomic organization of the human cholesterol-responsive ABC transporter ABCA7: tandem linkage with the minor histocompatibility antigen HA-1 gene.

We have recently cloned a novel cholesterol-responsive ABC transporter, designated ABCA7, which is predominantly expressed in human leukocytes. Here we report the structure of the human ABCA7 gene. The ABCA7 gene spans a region of approximately 32 kb and comprises 46 exons. Its putative promoter sequence contains potential binding sites for transcription factors with roles in hematopoiesis and cholesterol metabolism. Surprisingly, sequence analysis of the ABCA7 3' gene flanking region revealed that the terminal exon of ABCA7 borders immediately on the 5' end of the coding region of the recently identified human minor histocompatibility antigen HA-1. We demonstrate that the coding regions of ABCA7 and HA-1 are physically separated by a 1.7-kb intergene region. Subsequent genomic structure analysis showed that the HA-1 gene consists of 23 exons which extend across a 16-kb genomic region. Our results provide evidence that the genes for the human minor histocompatibility antigen HA-1 and the ABC transporter ABCA7 are arranged in a head-to-tail array and that both genes localize to a common locus of approximately 48 kb size on chromosome 19p13.3.

ABC transporters in cellular lipid trafficking.

ATP-binding cassette (ABC) transporters constitute a group of evolutionary highly conserved cellular transmembrane transport proteins. Recent work has implicated ABC transporters in cellular transmembrane lipid transport and hereditary diseases have been causatively linked to defective ABC transporters translocating lipid compounds. The emerging concept that a defined subset of ABC transporters is intimately involved in cellular lipid trafficking has recently been substantiated convincingly by the finding that ABCA1 plays a central role in the regulation of HDL metabolism and macrophage targeting to the RES or the vascular wall. Differentiation dependent expression of a large number of ABC transporters in monocytes/macrophages and their regulation by sterol flux render these transporter molecules potentially critical players in atherogenesis and other chronic inflammatory diseases.

The human leukotriene A4 hydrolase gene is expressed in two alternatively spliced mRNA forms.

We identified a novel short (s-) mRNA of the human leukotriene-A4 (LTA4) hydrolase using sequential reverse transcriptase PCR mapping. The s-mRNA is generated by skipping an 83 bp exon located in the 3' coding region and suggests the expression of an LTA4 hydrolase isoform with a calculated molecular mass of 59 kDa and a distinct C-terminus. Both LTA4 hydrolase mRNAs are constitutively expressed in blood cells, endothelial cells, smooth muscle cells, fibroblasts and tumour cells. The ratios of their mRNA expression levels are cell specific, with relatively high s-form mRNA expression in reticulocytes. Our data strongly suggest that the novel mRNA codes for the structurally related but distinct LTA4 hydrolase isoenzyme that has been postulated.

Identification of a novel human sterol-sensitive ATP-binding cassette transporter (ABCA7).

We report the identification of the full-length cDNA for a novel ATP-binding cassette (ABC) transporter from human macrophages. The mRNA is of 6.8 kb size and contains an open reading frame encoding a polypeptide of 2146 amino acids with a calculated molecular weight of 220 kDa. The predicted protein product is composed of two transmembrane domains and two nucleotide binding folds indicating that it pertains to the group of full-size ABC transporters. The novel transporter shows highest protein sequence homology with the recently cloned human cholesterol and phospholipid exporter ABCA1 (54%) and the human retinal transporter ABCR (49%), both members of the ABC transporter subfamily A. In accordance with the currently proposed classification, the novel transporter was designated ABCA7. ABCA7 mRNA was detected predominantly in myelo-lymphatic tissues with highest expression in peripheral leukocytes, thymus, spleen, and bone marrow. Expression of ABCA7 is induced during in vitro differentiation of human monocytes into macrophages. In macrophages, both the ABCA7 mRNA and protein expression are upregulated in the presence of modified low density lipoprotein and downregulated by HDL(3). Our results suggest a role for ABCA7 in macrophage transmembrane lipid transport.

n-3 fatty acids and cysteinyl-leukotriene formation in humans in vitro, ex vivo, and in vivo.

In humans, dietary n-3 fatty acids ameliorate some chronic inflammatory diseases. In contrast, however, dietary n-3 fatty acids had no effect in patients with bronchial asthma. In bronchial asthma, the cysteinyl-leukotrienes C4, D4, and E4, formed from arachidonic acid, are considered important mediators. They are as vasoconstrictive and bronchoconstrictive as leukotrienes C5, D5, and E5, cysteinyl-leukotrienes derived from eicosapentaenoic acid. Whether and how n-3 fatty acids affect human cysteinyl-leukotriene metabolism is largely unknown. We therefore investigated human cysteinyl-leukotriene metabolism in vitro, ex vivo, and in vivo in the absence and presence of dietary n-3 fatty acids. We demonstrate formation of leukotrienes C5, D5, and E5 from eicosapentaenoic acid in vitro and ex vivo in stimulated human granulocytes. Proof of formation relies on cochromatography with authentic standards on reverse-phase high-performance liquid chromatography, ultraviolet-absorbance spectra, and radioactive tracer studies. In vitro, amounts of leukotrienes C5, D5, and E5 formed depended on the amount of exogenous eicosapentaenoic acid; leukotrienes C4, D4, and E4 formed from endogenous arachidonic acid, however, remained unaltered. A randomized, controlled, observer-blind study in 14 human volunteers, seven of whom supplemented their diet with 7 gm/day of an 85% n-3 fatty acid concentrate for 6 weeks was subsequently performed. Ex vivo, levels of leukotriene E5 almost equaled those of leukotriene E4. Moreover, urinary excretion of leukotriene E4 was assessed to estimate formation of cysteinyl leukotrienes from arachidonic acid in vivo. Urinary excretion of leukotriene E4 was reduced by 35% after dietary supplementation with n-3 fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth factor mRNA profiles in unstimulated human mononuclear cells: identification of genes which are constitutively and variably expressed.

Quiescent human mononuclear cells (MNC) as studied ex vivo express highly specific mRNA patterns of growth factors: We recently demonstrated that unstimulated MNC constitutively express the genes for the A and B chains of platelet-derived growth factor (PDGF). This expression was down-regulated by dietary omega-3 fatty acids. We now report that unstimulated human MNC express the genes for platelet-derived endothelial cell growth factor (PD-ECGF), insulin-like growth factor (IGF-1A, -1B) and transforming growth factor-beta 1 (TGF-beta 1). In contrast, acidic and basic fibroblast GF (FGFs), insulin-like GF-2 (IGF-2), transforming GF-alpha (TGF-alpha) and epidermal GF (EGF) were not expressed in MNC, nor were alpha- and beta- receptors for PDGF. Quantitatively, as measured over a period of six weeks, expression of PD-ECGF was constant, whereas TGF-beta 1, IGF-1A, and IGF-1B were expressed at varying levels and all independently of each other. Dietary omega-3 fatty acids had no effect on gene expression. Our results also indicate that down-regulation of PDGF gene expression represents a specific and possibly therapeutic effect of dietary fish oil supplementation.

Dietary omega-3 fatty acids lower levels of platelet-derived growth factor mRNA in human mononuclear cells.

Platelet-derived growth factor (PDGF) is a potent mitogen thought to propagate atherosclerosis and other proliferative or inflammatory diseases. Some of these diseases are ameliorated in humans by ingestion of omega-3 fatty acids. We investigated mRNA expression of both PDGF-A and PDGF-B in quiescent peripheral blood mononuclear cells from healthy male volunteers. For this, a highly sensitive, quantitative polymerase chain reaction strategy (3n-PCR) was developed. In contrast to granulocytes, both PDGF-A and PDGF-B mRNAs are expressed in mononuclear cells. This expression occurs at a remarkably constant rate. Moreover, effects of 7 g/d of a 85% omega-3 fatty acid fish oil concentrate were investigated in a 6-week controlled, randomized, observer-blind study in 14 human volunteers, 7 of whom served as controls. omega-3 Fatty acids increased in mononuclear cell phospholipids. We demonstrate for the first time that diet affects human gene regulation. Dietary omega-3 fatty acids downregulate gene expression of both PDGF-A (-66%), and PDGF-B (-70%). This may represent a novel mechanism for the antifibrotic and antiatherosclerotic action of omega-3 fatty acids.