Disorder Of Lipoprotein Metabolism Research Articles

ATVB In Focus

Disorders of plasma lipoprotein metabolism (“dyslipidemia”) play a major role in the initiation and progression of atherosclerotic cardiovascular disease (ASCVD). Low-density lipoproteins (LDL), as well as other atherogenic apoB-containing lipoproteins, are known to promote cholesterol accumulation in macrophages as well as inflammatory responses within the vessel wall, leading to atherosclerosis progression. In addition, high-density lipoproteins (HDL) and their major apolipoprotein, apoA-I, promote the efflux of cholesterol from macrophages, the first step in the process of reverse cholesterol transport, and have other antiinflammatory and antioxidant effects that may contribute to inhibition of atherosclerosis. Pharmacological treatment to reduce levels of atherogenic lipoproteins, particularly the use of 3-hydroxy-3-methylglutaryl (HMG) coenzyme A (CoA) reductase inhibitors, or statins, has been proven in multiple large clinical outcome trials to significantly reduce the risk of cardiovascular events, generally by about one-third over five years. Indeed, the reduction of cardiovascular risk with statin therapy has been one of the greatest advances in medicine over the last two decades, and the expanding use of statin therapy will undoubtedly contribute to an important reduction in atherosclerotic cardiovascular disease over the next several decades. See page 482 However, the success of statin therapy has not eliminated the importance of continuing to develop new therapeutic approaches to the treatment of dyslipidemia. First, as the targets for …

Substrate reduction therapy for lysosomal storage diseases

The treatment of disordered lipoprotein metabolism with the statin class of drugs is one of the most striking successes in the field of applied medical science: here the use of selective inhibitors of the first committed step of cholesterol biosynthesis, in a complex and highly regulated pathway, leads to improved outcome from a common lipid storage disease that is a blight on whole populations--atherosclerosis. By the same token, substrate reduction is an emerging therapeutic strategy for the arcane field of the lysosomal storage diseases (LSDs). Reduced biosynthesis of glucosylceramide is postulated to allow correction of the imbalance between formation and breakdown of glycosphingolipids; the therapeutic effect of substrate reduction depends upon the presence of residual hydrolytic activity towards those accumulated glycosphingolipid substrates derived from glucosylceramide. First pioneered in the laboratory by Norman Radin, this approach has now been introduced into the clinic: based on the ability to inhibit uridine diphosphate glucosylceramide transferase, the semi-selective iminosugar, N-butyldeoxynojirimycin, is licensed for the treatment of type 1 Gaucher disease. Inhibition of substrate formation has wide application in the treatment of LSDs. Decreased glucosylceramide biosynthesis has therapeutic potential in glycosphingolipidoses other than Gaucher disease, and offers promise in several neurodegenerative storage disorders that are currently beyond the reach of other procedures. The results of ongoing clinical trials of miglustat in type 3 Gaucher disease, Niemann-Pick disease type C and GM2 gangliosidosis are eagerly awaited.

The molecular basis of familial hypercholesterolaemia in Turkish patients

Familial hypercholesterolaemia (FH) is an autosomal dominant disorder of lipoprotein metabolism. In the majority of patients FH is caused by mutations in the gene for the low-density lipoprotein receptor (LDLR), and to date more than 700 mutations have been reported worldwide. In this study, 36 paediatric patients with a clinical diagnosis of FH (20 homozygous and 16 heterozygotes) were screened for mutations in the LDLR gene. Each exon, with intron–exon junctions, was screened by capillary fluorescent SSCP (F-SSCP) and heteroduplex analysis. Samples showing different band patterns were sequenced. Ten novel (including three frame shift small deletions or insertions) and seven known mutations were detected. A total of 37 out of the predicted 56 FH-causing alleles were identified (66.1%). No patients with the R3500Q mutation in the APOB gene were found. W556R was the most common mutation, explaining 21.4% of the predicted defective LDLR alleles. The novel sequence changes were deemed to be pathogenic if they altered a conserved amino acid (L143P, D147E, Q233H-C234G, C347G) or occurred in or close to a splice site (IVS 16 + 5) and were absent in DNA from 50 healthy Turkish subjects. These data confirm the genetic heterogeneity of FH in Turkey, and demonstrate the usefulness of F-SSCP for mutation detection.

ABC Transporters and Sterol Absorption

Recent molecular studies, in particular investigations of subjects with monogenic disorders of lipoprotein metabolism and studies of induced-mutant mice, have increased the understanding of intestinal sterol absorption. Some of these genes encode adenosine triphosphate [ATP] binding cassette (ABC) transporters that transport dietary cholesterol from enterocytes back out to the intestinal lumen, thereby limiting the amount of cholesterol absorbed. ABC transporters also provide an effective barrier against the absorption of plant sterols, which are normally not absorbed in significant quantities by humans. This mechanism was clarified by the discovery that defects in two adjacent genes encoding ABC transporters are the molecular basis of sitosterolemia, a rare autosomal recessive disease in which plant sterols are absorbed due to failure of intestinal barrier to their absorption. Furthermore, recent experiments performed in induced-mutant mice have solidified the importance of these transporters in intestinal sterol absorption. Together with new developments in the biology of bile acids, sterol absorption is providing interesting directions for metabolism research. In addition to elucidating some of the molecular mechanisms of sterol absorption, these recent findings may lead to new therapeutic options to treat hypercholesterolemia and to help patients at risk of vascular disease reach ever-more stringent target levels.

31 Plasma Exchange Therapy for Severe Hypertriglyceridemia with Acute Pancreatitis

Background Serum triglyceride concentrations above 11 mmol/L can precipitate attacks of acute pancreatitis, although the pathogenesis of inflammation in this setting is unclear. In children with inherited disorders of lipoprotein metabolism that are associated with severe hypertriglyceridemia, attacks of acute pancreatitis can be prevented by lowering their serum triglycerides to less than 2.2 mmol/L. Some reports revealed favorable effects of membrane plasma exchange in severe hypertriglyceridemia and severe acute pancreatitis. The aim of our retrospective clinical study was to evaluate the efficacy of membrane plasma exchange (MPE) therapy in adult patients with severe hypertriglyceridemia and acute pancreatitis in terms of reduction of serum lipids, clinical improvement and reliability of the procedure itself.Methods 25 patients (pts; 24 men, 1 woman), aged 31–59 years (mean 44.6 ± 8.0) have been treated with MPE and LDL apheresis (one procedure) for severe hypertriglyceridemia and acute pancreatitis. Fresenius‐Excorim PE monitor and PF 2000 plasmafilter were used for MPE and Kaneka LDL monitor with dextran sulphate columns for LDL apheresis. Vascular access was via femoral catheter and peripheral vein in 16/25 pts (64%), 2 femoral catheters in 8/25 pts (32%), and 2 peripheral veins in 1/25 pt (4%). The anticoagulant used was heparin in 24/25 pts (96%) and citrate in 1/25 (4%). The replacement solution was a mixture of human albumin and hemofiltration solution. One to two volumes of plasma were exchanged per procedure.Results In total 42 procedures, 41 MPE and 1 LDL apheresis were carried out, mean 1.68 ± 1.0 per patient, one procedure in 14/25 pts (56%), 2 procedures in 7/25 pts (28%), 3 procedures in 3/25 pts (12%) and 5 procedures in 1/25 pt (4%). One volume of plasma was exchanged in 9/25 pts (36%), 1.5 volumes in 7/25 pts (28%) and 2 volumes in 9/25 pts (36%). From 3000–7200 mL of plasma was exchanged per procedure, mean 4724 ± 1806 mL. Mean running time was 185 ± 64 min., range 95–440 min. Triglyceride concentration before and after MPE was 53 ± 29 mmol/L (range 15.3‐109 mmol/L) and 12.9±10 mmol/L (range 1.5‐33.1 mmol/L), respectively. Total cholesterol before and after MPE was 18.9±8.2 mmol/L (range 8‐35) and 7.5 ± 5.4 mmol/L (range 0.6–22.6 mmol/L), respectively.Technical side effects were hemolysis in 1/42 MPE and plugging of the plasma filter with lipids, with substantial drop of plasma filtration rate in 3/42 MPEs. Hematoma after cannulation of the peripheral vein occurred in 2/42 MPE. Three patients had signs of hypocalcemia and were given Ca gluconate or calcium chloride.Conclusions In 25 patients with severe hypertriglyceridemia and acute pancreatitis substantial reduction of triglyceride and cholesterol serum concentration was achieved during plasma exchange therapy, along with clinical improvement of the patients.

Influence of proteinuria on disorders of lipoprotein metabolism

Summary: In order to assess the role of proteinuria in the development of lipoprotein metabolism derangements, we investigated 60 patients (32 males and 28 females, mean age 37.15 ± 9.85 years, average clearance of endogenous creatinine 86.27 ± 19.81 mL/min, average body mass index 24.18 ± 2.23 kg/m2), distributed in four groups according to degree of glomerular proteinuria. The control group, with urinary protein excretion 3.0 g/24h had significantly higher serum HDL cholesterol (p 3.0 g/24h as compared with patients with proteinuria ranging from 1.0 to 3.0 g/24h and control subjects (p<0.01). We therefore conclude that proteinuria causes disorders of LDL, VLDL, HDL and lipoprotein (a) metabolism.

Influence of proteinuria on disorders of lipoprotein metabolism

Influence of proteinuria on disorders of lipoprotein metabolism

Influence of proteinuria on the lipoprotein (a) metabolism disorder

Proteinuria causes lipid metabolism abnormalities. The aim of the present study was to examine the influence of proteinuria on the lipoprotein (a) metabolism disorder. The study included 60 patients of the male-famele ratio (M: F = 32 : 28), mean age 37.15 +/- 9.85 years with, the average endogenous creatinine clearance 86.27 +/- 19.81 ml/min, and the average body mass index (BMI) 24.18 +/- 2.23 kg/m2. Regarding the level of glomerular proteinuria, the patients were divided into four groups. The first (control) group, with proteinuria levels less than 0.25 g/24h, included 15 patients (M: F = 6 : 9), mean age 34.66 +/- 4.82 years, the mean clearance of endogenous creatinine 99.70 +/- 12.94 ml/min, and mean BMI 23.28 +/- 3.50 kg/m2. The second group, with proteinuria between 0.25 and 1.0 g/24 h, includ 15 patients (M: F = 9 : 6) with primary glomerulonephritis, mean age 37.87 +/- 9.65 years, the mean clearance of endogenous creatinine 82.85 +/- 18.48 ml/min, and mean BMI 23.83 +/- 1.57 kg/m2. The third group includ 15 patients (M : F = 8 : 7) with primary glomerulonephritis, with proteinuria between 1.0 and 3.0 g/24 h, mean age 35.67 +/- 13.29 years, the mean clearance of endogenous creatinine 82.85 +/- 18.48 ml/min, and mean BMI 23.83 +/- 1.57 kg/m2. The fourth group, with proteinuria higher than 3.0 g/24 h, included 15 patients (M: F = 9 : 6) with primary glomerulonephritis, mean age 40.40 +/- 9.75 years, the mean clearance of endogenous creatinine 80.16 +/- 20.80 ml/min, and mean BMI 24.83 +/- 1.44 kg/m2. In order to assess the influence of proteinuria on the lipoprotein (a) metabolism abnormalities we investigated 24-hour proteinuria, the colloid osmotic pressure (COP) of plasma, and the serum concentration of lipoprotein (a). The results were statistically analyzed using ANOVA, Kruscal-Wallis test, Mann-Whitney U test, chi2 test and Spearman test. Statistically, the patients with proteinuria over 3.0 g/24 h had the significantly higher values of lipoprotein (a) in serum as compared to the control group, and the patients with proteinuria about 0.25-1.0 g/24 h. The patients with proteinuria between 1.0-3.0 g/24 h had the statistically significantly higher values of lipoprotein (a) in serum than the control group (proteinuria < 0.25 g/24 h). There was a highly statistically significant negative correlation between serum albumin concentration, COP and the concentration of lipoprotein (a) in serum. There was a highly statistically significant positive correlation between 24-hour proteinuria and the concentration of lipoprotein (a) in serum. Proteinuria leads to the deterioration of lipoprotein (a) abnormalities.

Long-term effects of LDL apheresis in patients with severe hypercholesterolemia

Familial hypercholesterolemia (FH) is an inherited disorder of lipoprotein metabolism involving mutations in the LDL receptor (LDL-R). Patients with mutation in one (heterozygous) or both (homozygous) genes have markedly elevated LDL cholesterol and are at increased risk for coronary heart disease (CHD). Aggressive lipid lowering is required for homozygous and many heterozygous FH patients. This often involves LDL-apheresis, where LDL and other apo-B containing lipoproteins are selectively removed from the plasma. We have retrospectively studied 34 patients treated with biweekly LDL-apheresis at the Hospital of the University of Pennsylvania. In our patient population, adverse events were uncommon and rarely resulted in shortened treatment time. There was a dramatic decrease in the relative risk of cardiovascular events and cardiovascular interventions in patients treated with LDL-apheresis for an average of 2.5 years. Some but not all patients had long-term reduction in their LDL levels as a result of LDL-apheresis, suggesting that time-averaged reduction in LDL and/or LDL:HDL ratios were responsible for clinical improvement. These data support the use of LDL-apheresis in patients with FH, as well as medication-intolerant patients that have elevated LDL cholesterol despite maximal pharmacological treatment.

Phenotypic heterogeneity of sitosterolemia

Sitosterolemia is a rare autosomal recessive disorder of lipoprotein metabolism characterized by xanthomas and increased plasma concentrations of plant sterols, such as sitosterol. Causative mutations occur in either the ABCG5 or ABCG8 gene, each of which encodes a sterol half-transporter expressed in the intestine. We report five Canadian subjects with nonsense mutations in these half-transporters: four related Caucasian subjects were homozygous for the ABCG8 S107X mutation, and one unrelated Japanese-Canadian subject was homozygous for a complex insertion/deletion (I/D) mutation in ABCG5 exon 3. A female subject with each mutation was symptomatic with coronary atherosclerosis: a 5-year-old ABCG8 S107X homozygote and a 75-year-old ABCG5 exon 3 I/D homozygote; these represent the extreme ends of the spectrum of vascular involvement in sitosterolemia. The largest reductions in plasma concentrations of sitosterol and LDL-cholesterol were seen with ezetimibe or bile acid sequestrant treatment, and less dramatic reductions were seen with statin drug treatment. These findings extend the range of clinical phenotypes in sitosterolemia caused by nonsense mutations in either ABCG5 or ABCG8.

Guidelines applied in practice in medicare patients with acute myocardial infarction

Familial hypercholesterolemia (FH) is a genetic disorder of lipoprotein metabolism characterized by very high plasma concentrations of low density lipoprotein cholesterol (LDLc), tendon xanthomas and increased risk of premature coronary heart disease (CHD). FH is a public health problem throughout the world. There are 10,000,000 people with FH worldwide, mainly heterozygotes, and approximately 85% of males and 50% of females with FH will suffer a coronary event before 65 years old if appropriate preventive efforts are not implemented. Early identification of persons with FH and their relatives, and the early start of treatment are essential issues in the prevention of premature cardiovascular disease (CVD) and death in this population. However, guidelines for the general population formally exclude FH from their diagnostic and treatment recommendations. These guidelines have been elaborated by a group of international experts with the intention to answer the main questions about heterozygous FH (heFH) subjects that physicians worldwide face in the diagnosis and management of these patients.

Clinical, diagnostic, and therapeutic aspects of familial hypercholesterolemia.

Heterozygous familial hypercholesterolemia (FH) is a common inherited disorder of lipoprotein metabolism. FH is characterized by elevated levels of low-density lipoprotein cholesterol, the presence of tendon xanthomas, and premature cardiovascular disease. The underlying molecular defect of FH consists of mutations in the gene coding for the low-density-lipoprotein-receptor protein, detection of which provides the only unequivocal diagnosis. Although the cause of FH is monogenic, there is wide variation in the onset and severity of atherosclerotic disease in these patients. Additional atherogenic risk factors of environmental, metabolic, and genetic origin are presumed to influence the clinical phenotype in FH. Criteria used to identify individuals with FH include a combination of clinical characteristics, personal and family history of early coronary artery disease, and biochemical parameters. Since the introduction in 1989 of statins, which have been shown to be effective and to delay or prevent the onset of cardiovascular disease, drug treatment of FH has greatly improved. New lipid-lowering agents are presently being developed for clinical use. This review provides an update on the clinical, diagnostic, and therapeutic aspects of heterozygous familial hypercholesterolemia.

Guidelines for the diagnosis and management of heterozygous familial hypercholesterolemia

Familial hypercholesterolemia (FH) is a genetic disorder of lipoprotein metabolism characterized by very high plasma concentrations of low density lipoprotein cholesterol (LDLc), tendon xanthomas and increased risk of premature coronary heart disease (CHD). FH is a public health problem throughout the world. There are 10,000,000 people with FH worldwide, mainly heterozygotes, and approximately 85% of males and 50% of females with FH will suffer a coronary event before 65 years old if appropriate preventive efforts are not implemented. Early identification of persons with FH and their relatives, and the early start of treatment are essential issues in the prevention of premature cardiovascular disease (CVD) and death in this population. However, guidelines for the general population formally exclude FH from their diagnostic and treatment recommendations. These guidelines have been elaborated by a group of international experts with the intention to answer the main questions about heterozygous FH (heFH) subjects that physicians worldwide face in the diagnosis and management of these patients.

Four novel mutations in APOB causing heterozygous and homozygous familial hypobetalipoproteinemia.

Familial hypobetalipoproteinemia (FHBL) is a rare codominant disorder of lipoprotein metabolism characterized by low levels of low-density lipoprotein (LDL) cholesterol and apolipoprotein (apo) B. Heterozygotes for FHBL have less-than-half normal LDL-cholesterol and apoB concentrations, whereas homozygotes have extremely low or undetectable LDL-cholesterol and apoB levels. These reductions in LDL-cholesterol and apoB have been suggested to provide FHBL subjects with resistance to atherosclerosis. FHBL can be caused by mutations in the APOB gene on chromosome 2. We present four novel mutations and one previously described mutation in APOB causing FHBL in five families. Immunoblotting and DNA sequencing were used to characterize the novel mutation apoB-40.3 (c.5564_5565insC) and the previously reported mutation apoB-80.5 (c.11040T>G). The apoB-6.9 (c.1018_1025del) and apoB-25.8 (c.3600T>A) mutations were identified by DNA sequence analysis, as variants shorter than apoB-31 are not detectable in plasma. A fifth mutation, the splice variant c.82+1G>A, was identified by sequencing and was found in a homozygous subject. In approximately 50% of the FHBL subjects, plasma alanine aminotransferase concentrations were mildly increased, suggestive of fatty liver. All affected FHBL subjects had low to low-normal serum vitamin E concentrations, highlighting the important and recognized relationship between lipid and vitamin E concentrations.

Mouse models as tools for dissecting disorders of lipoprotein metabolism.

The overexpression of proteins as transgenes or by adenovirus-mediated gene transfer as well as the disruption of genes by homologous DNA recombination in the mouse provide powerful tools to dissect the role of individual proteins in complex biological pathways. These and similar techniques have been widely used to characterize the function of most of the players involved in lipoprotein metabolism. These models are expected to greatly advance the finding of new therapeutic strategies for the treatment of disorders of lipoprotein metabolism.

I. Background and Introduction

The Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III, or ATP III) presents the National Cholesterol Education Program's (NCEP's) updated recommendations for cholesterol testing and management. It is similar to Adult Treatment Panel II (ATP II)1,2 in general outline and fundamental approach to therapy. It focuses on the role of the clinical approach to prevention of coronary heart disease (CHD).* This report continues to identify low-density lipoprotein (LDL) as the primary target of cholesterol-lowering therapy. Since ATP II, a number of controlled clinical trials with newer cholesterol-lowering drugs have been reported. These trials demonstrated remarkable reductions in risk for CHD, in both primary and secondary prevention. Their results enrich the evidence base upon which the new guidelines are founded. The ATP III panel extensively analyzed the results of recent clinical trials whose findings strongly influenced the development of the new guidelines. The panel's major goals were to review the literature objectively and to document and display the scientific evidence for ATP III recommendations. Prior to the appointment of the ATP III panel, the NCEP Coordinating Committee developed a list of important issues for the panel's consideration. This list was presented to the panel, discussed, and modified appropriately. The literature pertaining to each defined issue was identified by the panel members and by a MEDLINE search. Panel members produced a series of issue papers that carefully reviewed the literature; these issue papers became the foundation for writing the first draft of the report. Modifications of drafts were made following review and discussion of additional evidence arising from the literature search. ATP III contains both evidence statements and specific recommendations based on these statements. Each evidence statement is qualified according to category of evidence (A—D) and strength …

Separation of Bovine Plasma Lipoproteins by a Rapid Ultracentrifugation Method

The recently described method of centrifugation with iodixanol for the rapid separation of human plasma lipoproteins was adapted to separate bovine plasma lipoproteins. Density gradients were generated by mixing plasma with iodixanol 12% (w/v), followed by centrifugation at 350000g and 16°C for 3h 10min in a vertical rotor. Gradients were unloaded dense-end first into 10 fractions. Human very low density lipoprotein (VLDL; density<1·011g/ml), low density lipoprotein (LDL; density=1·016–1·039g/ml) and high density lipoprotein (HDL; density=1·039–1·090g/ml) were resolved well at densities considerably lower than those traditionally reported in salt gradients. In gradients generated from 12% iodixanol, bovine LDL and HDL exhibited even lower densities (1·016–1·028 and 1·016–1·048g/ml, respectively) with all lipoproteins occurring at the lower density region of the gradient. In contrast, density gradients generated from layers of equal volumes of 6% and 12% iodixanol readily separated bovine HDL from VLDL, whilst LDL still overlapped with HDL. The latter accounts for >80% of all bovine lipoproteins and exists as two populations, namely light and heavy HDL. Gradients generated from two layers of iodixanol recovered bovine HDL in five fractions. The hypercholesterolaemia associated with lactation resulted in a modest shift in the profile of HDL cholesterol towards lipoprotein particles of lower density (light HDL). Significant between-farm differences were also detected in the density profiles of bovine plasma cholesterol. This new method is suitable for use in research and diagnosis in relation to lipoprotein metabolism disorders in cows.

Follow up after a family based genetic screening programme for familial hypercholesterolaemia: is screening alone enough?

Familial hypercholesterolaemia is an autosomal dominant disorder of lipoprotein metabolism, with an estimated frequency of 1 in 500 in Western countries; it results in excess mortality from coronary artery disease.1...

PPARs: transcription factors controlling lipid and lipoprotein metabolism.

Nuclear receptors are transcription factors that are activated by ligands and subsequently bind to regulatory regions in target genes, thereby modulating their expression. Nuclear receptors thus allow the organism to integrate signals coming from the environment and to adapt by modifying the expression levels of relevant genes. The peroxisome proliferator-activated receptors (PPARs) alpha, beta/delta, and gamma constitute a subfamily of nuclear receptors. PPARalpha has been shown to bind and to be activated by leukotriene B4 and the hypolipidemic drugs of the fibrate class; PPARbeta/delta ligands are polyunsaturated fatty acids and prostaglandins; while prostaglandin J2 derivatives and the antidiabetic glitazones are, respectively, natural and synthetic ligands for PPARgamma. Upon binding and activation by their ligands, they regulate the transcription of numerous genes involved in intracellular lipid metabolism, lipoprotein metabolism, and reverse cholesterol transport in a subtype- and tissue-specific manner. PPARs therefore constitute interesting targets for the development of therapeutic compounds useful in the treatment of disorders of lipid and lipoprotein metabolism.

Effect of promoters and enhancers on expression, transgene DNA persistence, and hepatotoxicity after adenoviral gene transfer of human apolipoprotein A-I.

Liver-directed gene transfer offers new perspectives for the treatment of inherited metabolic diseases and disorders of lipoprotein metabolism. Potent expression cassettes for transgenes in the liver may optimize gene transfer efficiency and improve the therapeutic index of gene transfer vectors. An E(1)-deleted adenovirus comprising the hepatocyte specific 256-base pair (bp) human apolipoprotein A-I (apo A-I) promoter, the genomic human apo A-I DNA, and four human apo E enhancers (AdA-I.gA-I.4xapoE) was associated with low hepatotoxicity, high transgene DNA persistence and absence of promoter shut-off, resulting in human apo A-I plasma levels above 100 mg/dl for 35 days in C57BL/6 mice. In the present investigation, the human apo A-I promoter was compared to the murine small nuclear RNA U1b, the human apolipoprotein C-II (apo C-II), and the human alpha(1) antitrypsin (hAAT) promoters and the effect of copy number and position of liver-specific human apo E enhancers in 16 adenoviral constructs was evaluated. The vector containing the 1.5-kb hAAT instead of the apo A-I promoter (AdhAAT.gA-I.4xapoE) induced 3.7-fold (p < 0.01) more human apo A-I reaching plasma levels above 300 mg/dl for 35 days. The composition of the expression cassette was a major determinant of human apo A-I transgene DNA copy number at day 35. Hepatotoxicity after adenoviral gene transfer was dependent on the promoter and the number of enhancers, and was higher with the enhancers in a 5' position. The combination of the hAAT promoter and four copies of the human apo E enhancer appears to be the expression cassette of choice for hepatocyte-specific overexpression of transgenes after gene transfer.