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Biomedical subjects

G Castro

Publications and source records attributed to G Castro.

At least 37 records · Page 2Linked to original sources
PubMed2000

Characterization and functional studies of lipoproteins, lipid transfer proteins, and lecithin:cholesterol acyltransferase in CSF of normal individuals and patients with Alzheimer's disease.

We investigated the lipoprotein distribution and composition in cerebrospinal fluid (CSF) in a group of patients with Alzheimer's disease (AD) or affected by other types of dementia in comparison to non-demented controls. We found slightly decreased apolipoprotein (apo)E and cholesterol concentrations in CSF of AD patients and moderately increased apoA-I concentrations, while in patients suffering from other types of dementia the apoA-I CSF concentration was increased. ApoA-IV concentrations varied widely in human CSF, but were not associated with any clinical condition. HDL(2)-like apoE-containing lipoproteins represent the major lipoprotein fraction. In CSF of normal controls, only a minor HDL(3)-like apoA-I-containing lipoprotein fraction was observed; this fraction was more prevalent in AD patients. ApoA-II was recovered mostly in the HDL(3) density range, while apoA-IV was not associated with lipoproteins but appeared in a lipid-free form, co-localizing with LCAT immunoreactivity. Bi-dimensional analysis demonstrated pre-beta and alpha apoA-I-containing particles; apoE and apoA-II were detected only in alpha-migrating particles. ApoA-IV distributed both to pre-beta and gamma-migrating particles; the LCAT signal was co-localized in this gamma-migrating fraction. Enzymatically active LCAT was present in human CSF as well as PLTP activity and mass; no CETP mass was detected. In CSF from AD patients, LCAT activity was 50% lower than in CSF from normal controls. CSF lipoproteins induced a significant cholesterol efflux from cultured rat astrocytes, suggesting that they play an active role in maintaining the cholesterol homeostasis in brain cells.

Alzheimer Disease↗
PubMed2000

Effects of alcohol on the major steps of reverse cholesterol transport.

The effects of moderate alcohol consumption on the capacity of blood sera to promote acceptance of cholesterol (C) from Fu5AH hepatoma cells, esterification of delivered free C, and transfer of produced cholesteryl esters to apolipoprotein (apo) B-containing lipoproteins have been studied. Twenty male subjects with relatively high (>50 mg/dl, n = 10) and low (<50 mg/dl, n = 10) high density lipoprotein (HDL) C levels consumed for eight weeks red grape wine (0.3 g ethanol/kg body mass per day). Alcohol consumption reduced total C and low density lipoprotein C levels in both groups of subjects. Low HDL C subjects showed an increase in HDL C, apo AI, apo AII, and lipoprotein (Lp) AI particle levels after alcohol consumption. Alcohol did not affect free C efflux from the cells. However, after the following period of substitution of alcohol with an isocaloric amount of red grape juice, cellular C efflux markedly reduced. While lecithin:cholesterol acyltransferase (LCAT) activity increased during alcohol consumption only in subjects with low HDL C, high HDL C subjects showed a significant decrease in cholesteryl ester transfer protein (CETP) activity. At the same time, alcohol consumption reduced the endogenous C esterification rate and increased the transfer of endogenous cholesteryl esters to apo B-containing lipoproteins in both groups. Thus, alcohol consumption in moderate doses enhanced the anti-atherogenicity of the serum lipoprotein spectrum, supporting more effective C efflux from peripheral cells and transport of accepted C to apo B-containing lipoproteins. The effects of alcohol on the reverse cholesterol transport depend on the initial HDL C level.

Adult↗
PubMed1999

Characterization of monoclonal antibodies against apolipoproteins A-I and A-II. Epitope expression in LpA-I and LpA-I:A-II particles.

Two monoclonal antibodies (MAbs) against apolipoprotein A-I (apo A-I), 6B9 and FF9B10, and one MAb against apolipoprotein A-II (apo A-II), 3F5, were characterized. To establish the epitope of apo A-I recognized by these antibodies, different experimental approaches were performed. First, competition between MAbs and the related epitopes on the same antigen was performed using double-determinant tests with previously characterized MAbs. Second, competition of different synthetic peptides of apo A-I in solution with apo A-I immobilized to solid phase was carried out. The MAbs against apo A-I (6B9 and FF9B10) appear to recognize discontinuous epitopes located in the amino-terminal region of the apo A-I. In competition experiments MAb 3F5 did not recognize central- or carboxy-terminal peptides of apo A-II. Furthermore, apo A-II was stronger recognized when it was included in HDL or LpA-I:A-II than in its purified form. So the epitope for 3F5 is better expressed in the lipoprotein structure. Finally, to establish the epitopes expression in different antigens in solution, competition of purified apo A-I, apo A-II, LpA-I, and LpA-I:A-II particles or HDL3, with apo A-I or HDL immobilized to solid phase, was carried out. The results showed that both MAbs against apo A-I reacted with poor affinity against free apo A-I, with high and similar affinities against Lp A-I and Lp A-I:A-II lipoparticles and with the highest affinity against HDL3. The MAb 3F5 against apo A-II recognized only LpA-I:A-II and not LpA-I lipoparticles.

Animals↗
PubMed1998

Selective uptake of cholesteryl esters from high-density lipoprotein-derived LpA-I and LpA-I:A-II particles by hepatic cells in culture.

Selective uptake of high-density lipoprotein (HDL)-associated cholesteryl esters (CE), i.e. lipid uptake independent of HDL particle uptake, delivers CE to the liver and steroidogenic tissues in vivo and in vitro. From human plasma HDL, two major subpopulations of particles can be isolated: one contains both apolipoprotein (apo) A-I and apo A-II (designated LpA-I:A-II) as dominant protein components, whereas in the other apo A-II is absent (LpA-I). In this study, selective CE uptake from LpA-I and LpA-I:A-II by cultured cells was investigated. LpA-I and LpA-I:A-II were isolated by immunoaffinity chromatography from human plasma high-density lipoprotein3 (HDL3, d = 1.125-1.21 g/ml) and both particles were radiolabeled in the protein (125I) as well as in the CE moiety ([3H]cholesteryl oleyl ether ([3H]CEt)). Several control experiments validated the labeling methodology applied. To investigate selective CE uptake, human Hep G2 hepatoma cells, human hepatocytes in primary culture and human skin fibroblasts were incubated in medium containing doubly radiolabeled LpA-I or LpA-I:A-II particles. Thereafter cellular tracer content was determined. For each cell type the rate of apparent lipoprotein particle uptake according to the lipid tracer ([3H]CEt) was in substantial excess over that due to the protein tracer (125I), demonstrating selective CE uptake from LpA-I as well as from LpA-I:A-II. This difference in uptake between [3H]CEt and 125I, i.e. the rate of apparent selective CE uptake, was significantly higher for LpA-I compared to LpA-I:A-II, and this was dose- as well as time-dependent. Thus in human hepatic cell and fibroblasts, CE are selectively taken up to a higher extent from LpA-I compared to LpA-I:A-II. These results may suggest that LpA-I particles of the human plasma HDL fraction may be those lipoproteins which more efficiently deliver CE to the liver via the selective uptake pathway whereas LpA-I:A-II may play a less important role.

Apolipoprotein A-I↗
PubMed1998

Displacement of apo A-I from HDL by apo A-II or its C-terminal helix promotes the formation of pre-beta1 migrating particles and decreases LCAT activation.

The displacement of apolipoprotein (apo) A-I by apo A-II is a major event in the remodeling of high density lipoproteins (HDL). In the present study, we investigated the displacement of apo A-I both from native and reconstituted HDL (rHDL) by either apo A-II or by the C-terminal helical peptide (i.e. residues 53-70). We studied the remodeling process of the original particles, the changes in size and composition and in their lecithin:cholesterol acyltransferase (LCAT) activating properties. Using gel filtration, we show that, at low apo A-II/AI ratios, the initial lipid apolipoprotein complex containing 2 mol apo A-I is remodeled into a mixed complex containing apo A-I and apo A-II, involving the displacement of one apo A-I by apo A-II. Upon addition of a larger amount of apo A-II, the rHDL particles become more heterogeneous and of larger size. Immunoblotting of the particles separated by non denaturing gradient gel electrophoresis shows that most of the apo A-I remains associated with the largest particles. The LCAT activation properties of the remodeled complexes decrease upon addition of either apo A-II or its C-terminal helix. This decrease is more pronounced when rHDL are incubated with the apo A-II C-terminal helix than with native apo A-II, as VmaX decreases from 28 to 16 and 7 nmol cholesteryl ester/ml per h respectively, whereas Km remains unchanged. The displacement of apo A-I observed with rHDL also occurred with native HDL particles as demonstrated by two-dimensional gel electrophoresis, using pyrene-phospholipid labeled HDL. Displacement of apo A-I generates pre-beta1 migrating particles containing apo A-I and phospholipids. We therefore propose that apo A-II has a dual effect on the role of HDL in reverse cholesterol transport: displacement of apo A-I from rHDL results in a negative control of the LCAT activity, while generation of pre-beta1 migrating particles enhances the formation of potential acceptors of cellular cholesterol.

Apolipoprotein A-I↗
PubMed1998

Branched synthetic peptide constructs mimic cellular binding and efflux of apolipoprotein AI in reconstituted high density lipoproteins.

This study investigates the suitability of the trimeric apolipoprotein (apo)AI(145-183) peptide that we recently described, to serve as a model to probe the relationship between apoAI structure and function. Three copies of the apoAI(145-183) unit, composed each of two amphipathic alpha-helical segments, were branched onto a covalent core matrix and the construct was recombined with phospholipids. A similar construct was made with the apoAI(102-140) peptide and used as a comparison with dimyristoylglycerophosphocholine (DMPC)-apoAI complexes. The DMPC-trimeric-apoAI(145-183) complexes had similar immunological reactivity with monoclonal antibodies directed against the 149-186 apoAI sequence (A44), suggesting that the A44 epitope is exposed similarly in both the synthetic peptide and the native apoAI complexes. The complexes generated with the trimeric-apoAI(145-183) bind specifically to HeLa cells with comparable affinity to the DMPC apoAI complexes; they are a good competitor for binding of apoAI to both HeLa cells and Fu5AH rat hepatoma cells; finally, these complexes promote cholesterol efflux from Fu5AH cells with an efficiency comparable with the apo AI/lipid complexes. To study LCAT activation by the trimeric apo AI(145-183) construct, complexes were prepared with dipalmitoylphosphatidylcholine (DPPC), cholesterol (C) and either the trimeric construct or apoAI. LCAT activation by the trimeric construct was much lower than by apo AI, possibly because the conformation of the trimeric 145-183 peptide in DPPC/C/peptide complexes does not mimic that of apoAI in the corresponding complexes. In comparison, the complexes generated with the multimeric apoAI(102-140) construct had a poor capacity to mimic the physico-chemical and biological properties of apoAI. The apoAI(102-140) construct had low affinity for lipid compared with the (145-183) construct. After association with lipids, it was a poor competitor of DMPC-apoAI complexes for cellular binding and had only limited capacity to promote cholesterol efflux. These results suggest trimeric constructs can serve as an appropriate models for apoAI, enabling further investigations and new experimental approaches to determine the structure-function relationship of apoAI.

Animals↗
PubMed1998

Dynamics of protein-protein docking: cytochrome c and cytochrome c peroxidase revisited.

The dynamics of the docking step in the electron transfer reaction between yeast cytochrome c peroxidase and iso-1-cytochrome c has been studied using the Brownian dynamics method. In particular we have calculated the bimolecular rate constant at which a specific complex, the xray crystalline complex, can form in solution by translational and rotational diffusion in a field of force. Complexation criteria have been assessed based on the simultaneous alignment of three atom-atom contacts, as well as alternative criteria. The proteins are able to align one or two contacts at remarkably high rates, in fact, at rates approaching the diffusion-controlled limit for two spheres reactive over their entire surfaces. Three contacts may align, and hence the specific complex may dock, at rates on the order of 10(8) M(-1) s(-1), which is quite representative of the experimental association rate constant for ET-competent complex(es). The formation of the specific complex is strongly influenced by the favorable electrostatic interaction between these proteins. It is striking that a specific protein-protein complex can form within one order of magnitude as fast as two spherical proteins can touch at any orientation. It remains plausible that the high ET tunneling rate in this system can take place through a single highly favorable specific complex using a single high efficiency pathway. Still the contribution from a nonspecific set of complexes is not ruled out, particularly considering the marginal reproduction of the ionic strength dependence in the formation of the xray complex.

Cytochrome c Group↗
PubMed1998

Effects of different dietary cholesterol concentrations on lipoprotein plasma concentrations and on cholesterol efflux from Fu5AH cells.

BACKGROUND: The fatty acid composition of the diet can modulate the effect of dietary cholesterol on plasma lipoproteins. However, HDL composition and its capacity to promote cholesterol efflux can be influenced by the diet. OBJECTIVE: Modifications in plasma lipids and in the capacity of serum to stimulate the cholesterol efflux induced by a low-fat diet [National Cholesterol Education Program (NCEP) Step I diet], by a monounsaturated fatty acid (MUFA)-rich diet, and by addition of cholesterol to both diets was studied. DESIGN: Fifteen young, healthy men followed 2 NCEP Step I diets (<30% of fat as energy, with <10% saturated fat and 14% MUFAs) for 24 d, providing 0.027 or 0.068 mg cholesterol x kJ(-1) x d(-1), and 2 oleic acid-enriched diets (38% of energy as fat, with 24% MUFAs) providing the same amount of dietary cholesterol as the NCEP Step I diets. RESULTS: Total cholesterol, LDL cholesterol, apolipoprotein (apo) B, and apo A-I concentrations decreased after the NCEP Step I and MUFA diets compared with the usual diet. HDL cholesterol also decreased after the NCEP Step I diet. Total:HDL cholesterol, apo B, and apo B:apo A-I were lower after the MUFA diets than after the NCEP Step I diets. There were no significant differences between the lipid profiles obtained after the NCEP Step I and MUFA diets were enriched with cholesterol. The capacity of serum to promote cholesterol efflux was significantly higher after the cholesterol-enriched NCEP Step I diet than after the NCEP Step I diet. CONCLUSIONS: The MUFA diet induced a better lipid profile than the NCEP Step I diet; however, the increase in the cholesterol content of both diets produced similar plasma lipid changes. The cholesterol in the NCEP Step I diet increased the cholesterol efflux induced by total serum.

Adult↗
PubMed1997

Hepatic lipase deficiency increases plasma cholesterol but reduces susceptibility to atherosclerosis in apolipoprotein E-deficient mice.

The effect of hepatic lipase (HL) deficiency on the susceptibility to atherosclerosis was tested using mice with combined deficiencies in HL and apoE. Mice lacking both HL and apoE (hhee) have a plasma total cholesterol of 917 +/- 252 mg/dl (n = 24), which is 184% that of mice lacking only apoE (HHee; 497 +/- 161 mg/dl, n = 20, p < 0. 001). The increase in cholesterol was mainly in beta-migrating very low density lipoproteins, although high density lipoprotein cholesterol (HDLc) was also increased (53 +/- 37 versus 20 +/- 13 mg/dl, p < 0.01). Despite the increase in plasma cholesterol, we found that HL deficiency significantly decreased aortic plaque sizes in female mice fed normal chow (31 x 10(3) +/- 22 x 10(3) microm2 in hhee versus 115 x 10(3) +/- 69 x 10(3) microm2 in HHee, p < 0.001). Reduction of plaque sizes was also observed in female heterozygous apoE-deficient mice fed an atherogenic diet (2 x 10(3) +/- 2.5 x 10(3) microm2 in hhEe versus 56 x 10(3) +/- 49 x 10(3) microm2 in HHEe, p < 0.01). Changes in aortic lesion size were not apparent in the small number of male mice studied. In HHee females, both HDLc and the capacity of high density lipoprotein (HDL) particles to promote cholesterol efflux from cultured cells were 26% of the wild type. The absence of HL in hhee females partially restored HDLc levels to 57% and cholesterol efflux to 55% of the wild type. Circulating pre-beta1-migrating HDL were present in all mutants, suggesting that there are alternative pathways in the formation of these pre-beta-HDL not involving apoE, HL, or cholesteryl ester transfer protein. The improved capacity to promote cholesterol efflux, together with increased HDL, may explain why these animals can overcome the increase in atherogenic lipoproteins.

Animals↗
PubMed1997

Cholesterol efflux, lecithin-cholesterol acyltransferase activity, and pre-beta particle formation by serum from human apolipoprotein A-I and apolipoprotein A-I/apolipoprotein A-II transgenic mice consistent with the latter being less effective for reverse cholesterol transport.

Studies assessing fatty streak formation in mice have revealed that human apolipoprotein A-I (apoAI) transgenic mice (TgAI) have 15-fold less atherosclerosis susceptibility than combined human apolipoprotein A-I/human apolipoprotein A-II (apoAI:AII) transgenics (TgAI:AII) and 40-fold less than nontransgenic control mice. In order to examine the biochemical mechanisms underlying those in vivo observations, we have compared in vitro properties of serum from the different groups of animals for participation in cholesterol efflux, LCAT activation, and pre-beta particle formation. Analysis of cholesterol efflux from both Fu5AH hepatoma and Ob1771 adipose cells revealed serum from the TgAI to be the most efficient in promoting efflux. The two-dimensional electrophoresis of mouse serum shows that control mice have exclusively apoAI in alpha particles. TgAI and TgAI:AII mice have 30 and 38% of total apoAI in particles with pre-beta electrophoretic mobility, respectively. The distribution of cell-derived cholesterol between these apoAI-containing lipoprotein subspecies after 1 and 60 min of incubation with Fu5AH hepatoma cells was examined. This revealed after a 1 min incubation 66 +/- 8 and 83 +/- 9% of the counts in particles with pre-beta mobility for TgAI and TgAI:AII mice, respectively; while after 60 min of incubation, only 6 +/- 2% of counts remained in pre-beta particles from the TgAI and 30 +/- 3% for the TgAI:AII. This suggests faster movement of cholesterol from pre-beta to alpha particles in plasma from the TgAI. Consistent with this is the observation that LCAT activity with both exogenous and endogenous substrate increased in the TgAI versus the TgAI:AII mice. The previously observed decrease in fatty streak formation in the TgAI versus the TgAI:AII and control mice is consistent with the in vitro studies presented here and suggests that HDL containing human apoAI is a more effective participant in the postulated early steps in reverse cholesterol transport than HDL containing both human apoAI and human apoAII, and/or murine HDL.

Animals↗
PubMed1997

Fish-eye disease: structural and in vivo metabolic abnormalities of high-density lipoproteins.

Fish-eye disease (FED) in humans is characterized by corneal opacities and markedly decreased plasma concentrations of high-density lipoprotein (HDL) cholesterol, apolipoprotein (apo) AI, and apo All, but no tendency to precocious atherosclerosis is present. To elucidate this paradox, the structure of HDL, the potential of serum to promote cholesterol efflux from cultured cells, and the in vivo metabolism of HDL were examined in a 53-year-old woman with a FED syndrome in association with a markedly decreased lecithin:cholesterol acyltransferase (LCAT) activity in HDL due to a mutation of the LCAT gene (Arg158 --> Cys). HDLs isolated by ultracentrifugation were small and enriched in unesterified cholesterol and phospholipids at the expense of cholesteryl esters and proteins. The apolipoprotein content showed an enrichment in apo E and apo AIV, whereas apo AI and apo All were dramatically reduced. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting using specific antibodies showed that the apo E was free or covalently bound to apo All. These particles analyzed by electron microscopy were small and round lipoproteins with a size similar to the smallest fraction of normal HDL3. The potential capacity of the serum to promote efflux from the cells was approximately 40% of control serum levels, but FED HDLs were as efficient as control HDLs in promoting cholesterol efflux from cells. To assess the metabolism of HDL apolipoproteins, in vivo apolipoprotein kinetic studies were performed using endogenous labeling techniques in the patient with FED and three control subjects. All subjects were administered D3-labeled leucine by primed constant infusion for up to 10 hours. The fractional synthetic rates (FSRs) of apo AI and apo All in the patient were 0.674 and 0.594 per day, clearly higher than in controls, 0.210 +/- 0.053 and 0.148 +/- 0.014 per day for apo AI and apo All, respectively. Apo AI and apo All production rates in the patient with FED were normal, 11.32 and 2.62 mg/kg x d, respectively, as compared with those in normal subjects, 11.45 +/- 1.23 and 2.68 +/- 0.17 mg/kg x d. These data established that hypoalphalipoproteinemia in FED was caused by marked hypercatabolism of apo AI and apo All. This hypercatabolism could be the consequence of structural abnormalities due to the selective LCAT deficiency. In conclusion, two steps of reverse cholesterol transport, cholesterol efflux and apo-HDL metabolism, appeared particularly efficient. This efficiency could participate in the absence of premature atherosclerosis in FED patients as regards the low HDL level.

Adult↗
PubMed1997

Subclasses of LpA-I in coronary artery disease: distribution and cholesterol efflux ability.

We analysed the distribution of LpA-I particles according to their molecular weight in 34 men with symptomatic coronary artery disease (CAD) and 11 men with no symptoms of CAD (control group). Using an original rapid and reproducible gradient gel electrophoresis technique, three LpA-I subclasses were defined: large (L-LpA-I), intermediate (I-LpA-I) and small LpA-I (S-LpA-I). The proportion of L-LpA-I was significantly lower in the CAD group (37.5 +/- 18.5%) than in the control group (58.9 +/- 15.0%) (P < 0.01). Conversely, a significantly (P < 0.05) higher proportion of I-LpA-I (31.9 +/- 20.7%) was observed in the CAD group compared with the control group (14.2 +/- 8.2%). Also, in the CAD group, the proportion of L-LpA-I was positively associated with the plasma level of LpA-I (P < 0.05) and, conversely, the proportion of S-LpA-I was negatively associated with LpA-I levels (P < 0.01). L-LpA-I and I-LpA-I from CAD patients and from control subjects were most effective in promoting cholesterol efflux from Fu5AH rat hepatoma cells, whereas S-LpA-I was ineffective in this regard. In conclusion, the decreased ratio in CAD patients of L-LpA-I, lipoprotein subspecies that are required for cholesterol efflux from cells, suggests a potential anti-atherogenic effect of these particles associated with the larger LpA-I subfractions.

Aged↗
PubMed1997

In vivo glucosylated LpA-I subfraction. Evidence for structural and functional alterations.

This study compared the structural and functional properties of glucosylated and non-glucosylated LpA-I particle subfractions (GLpA-I and NGLpA-I, respectively) isolated from patients with poorly controlled type 1 (insulin-dependent) diabetes. Compared with NGLpA-I, GLpA-I showed an enrichment in triglycerides (P < .05) and a depletion in phospholipid (P < .05) content. Moreover, the triglycerides-to-cholesteryl esters ratio was increased (P < .05), suggesting an increased cholesteryl ester transfer protein activity and a possible transport defect that accelerates atherogenesis. The surface-to-core constituents ratio, an indirect estimate of particles size, is lower in GLpA-I (P < .01) than in NGLpA-I, correlating well with a larger median size (P < .05) as seen by electron microscopy. The apolipoprotein (apo) A-I conformation was evaluated through determination of the immunological accessibility of three different domains defining specific epitopes for anti-apo A-I monoclonal antibodies. We observed a marked decreased accessibility for two of these regions, which interestingly have already been implicated in the interaction with cells. Cell culture data suggest that nonenzymatic glycosylation occurring on apo A-I can modify lipoprotein function, since it results in a decreased binding of GLpA-I to HeLa cells and impaired cholesterol efflux from Fu5AH rat hepatoma cells.

Animals↗
PubMed1996

Cholesterol efflux from Fu5AH hepatoma cells induced by plasma of subjects with or without coronary artery disease and non-insulin-dependent diabetes: importance of LpA-I:A-II particles and phospholipid transfer protein.

We measured the capacity of human plasma to induce cholesterol efflux from Fu5AH rat hepatoma cells in four groups of men with or without non-insulin-dependent diabetes mellitus (NIDDM) and coronary artery disease (CAD). Plasma from men with both NIDDM and CAD (n = 47) had the lowest efflux capacity (17.3 +/- 3.6%) whereas healthy control subjects with neither diabetes nor CAD (n = 25) had the highest capacity (19.8 +/- 3.4%). The groups with CAD but no diabetes (n = 44) and with NIDDM but no CAD (n = 35) had intermediate efflux values (18.5 +/- 3.8 and 18.5 +/- 3.9%, respectively). In a 2 x 2 factorial ANOVA, the differences were significant with respect to the presence of CAD (P = 0.038) and NIDDM (P = 0.041), with no interaction between the factors. The concentration of HDL particles containing apolipoprotein (apo) A-I but no apo A-II (LpA-I) was not related to efflux capacity in univariate or multivariate analyses. A multivariate regression analysis showed that when controlled for the presence of NIDDM and CAD, the concentration of particles containing both apo A-I and apo A-II (LpA-I:A-II) and plasma phospholipid transfer protein activity were both positively, independently, and significantly (P < 0.001) related to cholesterol efflux capacity.

Aged↗
PubMed1996

Potential gene therapy for lecithin-cholesterol acyltransferase (LCAT)-deficient and hypoalphalipoproteinemic patients with adenovirus-mediated transfer of human LCAT gene.

BACKGROUND: Overexpression of human lecithin-cholesterol acyltransferase (LCAT) in transgenic mice results in an increase of the antiatherogenic HDLs. METHODS AND RESULTS: To investigate the potential use of LCAT for gene therapy, a recombinant adenovirus was constructed in which the human LCAT cDNA was expressed under the control of the human cytomegalovirus immediate/early promoter followed by a chimeric intron (AdCMV human LCAT). Human apolipoprotein (apo) A-I transgenic mice infected with AdCMV human LCAT by intravenous injection accumulated reactive LCAT in the plasma. LCAT activity was increased 201-fold in the plasma of mice infected with 1 x 10(6) pfu AdCMV human LCAT, from 45 +/- 2 to 9068 +/- 812 nmol.mL-1.h-1, in comparison with basal LCAT activity measured in control mice, 5 days after injection. Plasma HDL cholesterol levels rose from 117 +/- 12 to 797 +/- 48 mg/dL, and plasma human apo A-I concentrations increased from 247 +/- 14 to 616 +/- 17 mg/dL, in AdCMV human LCAT infected mice compared with control mice. HDL particles were larger and had a different electrophoretic mobility. Studies of cholesterol efflux by incubation of serum with cholesterol-loaded Fu5AH cells showed that serum from AdCMV human LCAT-infected mice promoted a significantly higher efflux than did that of the controls. CONCLUSIONS: These data establish the potential of this approach for treatment of subjects with LCAT gene defects as well as patients with low plasma levels of apo A-I and HDL cholesterol.

Adenoviridae↗
PubMed1996

Protection against atherogenesis in mice mediated by human apolipoprotein A-IV.

Apolipoproteins are protein constituents of plasma lipid transport particles. Human apolipoprotein A-IV (apoA-IV) was expressed in the liver of C57BL/6 mice and mice deficient in apoE, both of which are prone to atherosclerosis, to investigate whether apoA-IV protects against this disease. In transgenic C57BL/6 mice on an atherogenic diet, the serum concentration of high density lipoprotein (HDL) cholesterol increased by 35 percent, whereas the concentration of endogenous apoA-I decreased by 29 percent, relative to those in transgenic mice on a normal diet. Expression of human apoA-IV in apoE-deficient mice on a normal diet resulted in an even more severe atherogenic lipoprotein profile, without affecting the concentration of HDL cholesterol, than that in nontransgenic apoE-deficient mice. However, transgenic mice of both backgrounds showed a substantial reduction in the size of atherosclerotic lesions. Thus, apoA-IV appears to protect against atherosclerosis by a mechanism that does not involve an increase in HDL cholesterol concentration.

Animals↗
PubMed1996

Inhibition of atherosclerosis development in cholesterol-fed human apolipoprotein A-I-transgenic rabbits.

BACKGROUND: Prospective epidemiological studies support the hypothesis that high levels of high-density lipoprotein (HDL) cholesterol and apolipoprotein (apo) A-I limit atherosclerosis development. However, more data from studies with animal models of atherosclerosis that resemble the human disease are required to demonstrate the effect of apo A-I in the inhibition of atherogenesis. The rabbit is a good animal model for human atherosclerosis. METHODS AND RESULTS: Human apo A-I-transgenic rabbits have been produced, and we have evaluated the effect of apo A-I on the development of atherosclerosis in transgenic rabbits fed a cholesterol-rich diet for 14 weeks. Plasma cholesterol levels of atherogenic apo B-containing lipoproteins were similar for transgenic and control rabbits (> 1000 mg/dL), while plasma levels of HDL cholesterol in the transgenic group were always about twice that of the control group (68 +/- 11 versus 37 +/- 3 mg/dL at 14 weeks; P < .001). At the end of the experiment, the amount of aortic surface area covered by lesions as well as the amount of lipid accumulation in the aorta were significantly less in transgenic rabbits compared with the control group (15 +/- 12% versus 30 +/- 8%, P < .0027 for the surface area of the thoracic aorta; 116 +/- 31 versus 247 +/- 39 mumol/g aorta, P < .0068 for cholesterol content in total aorta). CONCLUSIONS: Overexpression of human apo A-I in rabbits inhibits the development of atherosclerosis in this animal model that resembles, in many respects, human atherosclerosis.

Analysis of Variance↗