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PubMed2005

Effect of cholesterol and ethanol on dermal delivery from DPPC liposomes.

The main objective of the present work was to compare the dermal delivery of minoxidil (Mx), a lipophilic drug from ethosomes versus classic liposomes, containing different cholesterol (CHOL) concentrations. All the systems were characterized for shape, lamellarity, particle size and entrapment efficiency percentage (EE), by transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM), laser diffraction and ultracentrifugation or dialysis methods, respectively. Multilamellar vesicles (MLVs) were obtained and one to six lamellae were visualized by CLSM. The presence of ethanol in the formulations affects the particle size in terms of reducing this parameter. In addition, it was possible to appreciate the influence of CHOL on the vesicle size, because it was increased, as CHOL concentration was higher. When the EE was determined by two different methods (ultracentrifugation and dialysis methods), a clear losing of entrapped drug by the ultracentrifugation method was observed, because the strong energy transmitted to the samples disrupted vesicles. Vesicles were non-occlusively applied on rat skin and the permeation pattern of the different systems, depth into the skin and the main permeation pathway were studied by using beta-carotene as a fluorescent probe. CLSM studies showed that ethosomal systems were much more efficient at delivering the fluorescent substance into the skin in terms of quantity and depth, than either liposomes or hydroalcoholic solutions.

Androstanes↗

PubMed2004

Efficient purification of bromoviruses by ultrafiltration.

Ultrafiltration using polyethersulfone-membranes was evaluated as an efficient and preferred method for purifying Cowpea Chlorotic Mottle Virus (CCMV). Cesium chloride (CsCl) ultracentrifugation and ultrafiltration protocols are described, and comparative UV-spectroscopic and electron micrograph results are presented. CCMV purified by ultrafiltration are shown to be equivalent to CCMV purified by ultracentrifugation, while reducing purification time by two days and avoiding the need for expensive capital overheads such as ultracentrifuges, rotors and toxic CsCl chemical waste.

Bromovirus↗

PubMed2004

Purification of the recombinant hepatitis B virus core antigen (rHBcAg) produced in the yeast Saccharomyces cerevisiae and comparative observation of its particles by transmission electron microscopy (TEM) and atomic force microscopy (AFM).

Hepatitis B virus core antigen (HBcAg) gene (C gene) was expressed in Saccharomyces cerevisiae and the products (rHBcAg or core particles) were purified from a crude lysate of the yeast by three steps: Sephrose CL-4B chromatography, Sucrose step-gradient ultracentrifugation and CsCl-isopycnic ultracentrifugation. It has been observed that HBcAg was synthesized in yeast cells as a particle consisting of polypeptides with a molecular weight of 21.5 kDa (p21.5). Results of ELISA test and density analysis of CsCl-isopycnic ultracentrifugation indicated that the purified products (rHBcAg particles) with HBcAg antigenicity mainly located at the densities of 1.27 and 1.40 g ml(-1), respectively. Observation and analysis of the purified rHBcAg products by TEM indicated that rHBcAg peptides could mainly self-assemble into two size classes of core particles. The larger particles were approximately 30.1 nm and the smaller were approximately 21.5 nm in mean diameter. Further observation and analysis of the same rHBcAg (core) particles by AFM also indicated that rHBcAg (core) particles were similar to the native HBcAg (core) particles from infected human hepatocytes and mainly composed of two size classes of partides core. The larger particles were approximately 31.3 nm and the smaller were approximately 22.5 nm in mean diameter which was similar to the results obtained by TEM. All results from both TEM and AFM suggested that core particles (capsids) produced in S. cerevisiae possessed dimorphism.

Genes, Viral↗

PubMed1998

Protein binding of aspirin and salicylate measured by in vivo ultrafiltration.

OBJECTIVE: Methods for measuring protein binding of drugs generally require direct measurement of the concentration of unbound drug and thus may require a highly sensitive assay. In vivo ultrafiltration has been used to determine protein binding of endogenous substances. We have examined its value for measuring protein binding of drugs because it requires measurement of only the concentration of total drug, not unbound drug, in plasma. METHODS: The protein binding of aspirin and its metabolite salicylate was measured in 29 healthy subjects 20 minutes after a single oral dose of 600 mg soluble aspirin, by the new method, in vivo ultrafiltration, as well as by a standard method, in vitro ultracentrifugation. RESULTS: The data for salicylate were examined systematically to determine the optimal method of determining estimates of protein binding by in vivo ultrafiltration. Estimates of protein binding of salicylate were 81.7% +/- 10.1% (mean +/- SD) by the in vivo method and 81.6% +/- 11.3% by in vitro ultracentrifugation. Bland-Altman analysis of agreement showed that within-individual differences in percentage of protein binding determined by the two methods did not differ significantly from zero (mean difference, 0.07%; 95% confidence interval, -2.33 to +2.46). There was a highly significant correlation between estimates of protein binding by the two methods (r = 0.82; p = 0.001). Protein binding of aspirin was estimated of protein binding by the two methods (r = 0.82; p = 0.001). Protein binding of aspirin was estimated at 58.3% +/- 9.6% by in vivo ultrafiltration and could not be estimated by in vitro ultracentrifugation because the concentration of unbound aspirin in plasma was below the limit of detection for the assay. CONCLUSION: In vivo ultrafiltration can be used to measure protein binding of drugs and has potential advantages over conventional methods. A sensitive assay may not be required because the unbound drug need not be measured, measurement in vivo may maintain more physiologic conditions, and it may be useful in measuring protein binding of drugs that are degraded rapidly in vitro.

Adult↗

PubMed2004

Evidence for a macroscopic electric field in the sedimentation profiles of charged colloids.

The determination of molecular masses from barometric sedimentation profiles, a main topic in ultracentrifugal analysis, is thought to be quantitatively correct for non-interacting particles. Whereas this expectation is justified for uncharged colloids or macromolecules at low volume fractions, early ultracentrifugation studies on charged particles had already indicated that the obtained masses might be much too low. More recently, expanded sedimentation profiles have been observed for charged particles, sometimes inflated by orders of magnitude relative to the barometric prediction, which highlights a shortcoming in our understanding of centrifugation of even very dilute charged species. Theory and simulations, anticipated by various authors, now propose that strongly non-barometric sedimentation profiles might be caused by an internal macroscopic electric field that, even for non-interacting particles, significantly decreases the buoyant particle mass. The existence of this field and its intriguing consequences still lack experimental verification. Here we report ultracentrifugation experiments on charged colloidal silica spheres, showing both the existence of such a macroscopic electric field and its drastic effects on the sedimentation profiles of very dilute dispersions at low ionic strength.

Journal Article↗

PubMed1977

The separation and characterization of bronchial glycoproteins by density-gradient methods.

1. Sputum samples from a total of 18 asthmatic and chronic bronchitic patients were examined by analytical density-gradient ultracentrifugation. CsBr was used as the dispersal agent and dense electrolyte. 2. The patterns show two main groups of components, banding at about 1.3g/ml and 1.5g/ml; in addition, a few samples showed a further zone at approx. 1.65g/ml. These components were identified as protein, secretory glycoprotein and DNA respectively. The glycoprotein zone was frequently hypersharp, and usually contained two or more partially resolved bands; it was always well resolved from the protein. 3. The glycoprotein components were isolated from nine representative sputum samples by density-gradient ultracentrifugation on a preparative scale. Analytical density-gradient ultracentrifugation was used to monitor the efficiency of the separations. 4. Some sputum samples separated cleanly under these conditions, the glycoprotein being essentially devoid of free protein; in others, separation was apparently incomplete, although computer simulation indicated that the conditions were adequate to ensure separation. Further density-gradient separations in CsCl were necessary with several samples before satisfactory products were obtained; mixtures of CsCl with guanidinium chloride were no more effective than CsCl alone. The reluctance to separate indicates a very strong, but non-covalent, interaction between protein and glycoprotein, probably associated with the gelatinous character of the secretion. 5. The purified glycoprotein components were characterized analytically and physicochemically. They contained N-acetylgalactosamine, N-acetylglucosamine, galactose, fucose and N-acetylneuraminic acid, and had an amino acid composition in which serine, threonine and proline predominated; however, aspartic acid, glutamic acid and cystine were also appreciable. The glycoproteins were of very high molecular weight, and usually showed more than one component in sedimentation velocity; their distribution in a density gradient indicated a substantial, but largely monotonic, density heterogeneity. 6. Thiol reduction decreased the molecular weight very substantially, but the products were relatively more homogeneous than the native materials. The amino acid composition was changed significantly and a small and variable proportion of protein or peptide was liberated. It is concluded that the native materials are disulphide-linked aggregates, probably through a cross-linking peptide, in confirmation of earlier studies.

Amino Acids↗

PubMed1999

GBV-C/HGV-RNA in serum and peripheral blood mononuclear cells in hemodialysis patients.

BACKGROUND: Hemodialysis patients are at high risk of hepatitis B, C, and G virus infection. The prevalence of GBV-C/HGV-RNA was analyzed in serum and peripheral blood mononuclear cells (PBMCs) from 52 hemodialysis patients. METHODS: GBV-C/HGV-RNA detection was performed by reverse transcription-polymerase chain reaction (RT-PCR) with primers of 5'-noncoding (5'-NC) and NS3 regions of the GBV-C/HGV genome. To increase sensitivity, serum samples were ultracentrifuged prior to the RT-PCR to concentrate the viral particles. The amplified products from 20 serum and 5 peripheral blood mononuclear cells (PBMC) samples were sequenced. RESULTS: GBV-C/HGV-RNA was detected in sera of 9 (17%) and in PBMCs of 30 (58%) patients. After serum ultracentrifugation, GBV-C/HGV-RNA was positive in 20 (95%) of the patients, with GBV-C/HGV-RNA only in PBMCs. Thus, GBV-C/HGV-RNA was detected in serum and PBMCs from 29 (56%) patients, four of whom had antibodies against GBV-C/HGV E2 protein (anti-HGE2); one patient (2%) had GBV-C/HGV-RNA only in PBMCs, but was anti-HGE2 positive. Seven (32%) patients who did not have GBV-C/HGV-RNA were anti-HGE2 positive. The nucleotide sequence homology between serum samples from the patients who were GBV-C/HGV-RNA positive after ultracentrifugation, and paired serum and PBMCs from five of them, ranged from 90 to 96% and from 92 to 98%, respectively. CONCLUSIONS: We found a high prevalence of GBV-C/HGV-RNA in serum and PBMC samples from hemodialysis patients. Whether or not this finding can be extended to other populations requires further study.

Aged↗

PubMed1992

Binding of transition metals by apolipoprotein A-I-containing plasma lipoproteins: inhibition of oxidation of low density lipoproteins.

We have found transition metals tightly bound to apolipoprotein A-I-containing lipoproteins [Lp(A-I)] isolated by selected affinity immunosorption from human serum. Prominent among the metal ions detected were iron and copper. By immunoblotting the proteins of Lp(A-I), we detected both transferrin and ceruloplasmin. The transferrin-containing Lp(A-I) particles, isolated by selected affinity immunosorption against transferrin, were larger (mean diameter of 14.2 nm) and had a higher protein content than most high density lipoproteins (HDL). Ultracentrifugally isolated HDL were found to contain much less transferrin, whereas transferrin was found associated with apolipoprotein A-I from the greater than 1.21-g/ml ultracentrifugal fraction. This suggests that the complex is not recovered in the classic HDL density interval because of its very high density. HDL inhibit copper-catalyzed oxidation of low density lipoproteins (LDL) in vitro. We have found that immunoisolated Lp(A-I) are an order of magnitude more effective in inhibiting the oxidation of LDL than ultracentrifugally isolated HDL, on the basis of protein mass. When the Lp(A-I) particles containing transferrin and ceruloplasmin were removed from the bulk of Lp(A-I), inhibition of the in vitro oxidation of LDL was significantly decreased.

Apolipoprotein A-I↗

PubMed1956

Microsomal nucleoprotein particles from pea seedlings.

Ultracentrifugal analysis of an extract of pea epicotyls, previously freed of debris and larger particles by centrifugation at 40,000 g for 10 minutes, has revealed the presence of a major component which possesses a sedimentation coefficient of 74 S. This component constitutes about 25 per cent of the TCA-precipitable material in the clarified epicotyl extract and is estimated to make up 1 to 2 per cent of the dry weight of the original tissue. In size, chemical composition, and morphology, the 74 S component resembles the nucleoproteins of the microsomes from animal tissues. The 74 S component of pea epicotyl extracts has been purified by repeated cycles of differential centrifugation to yield a preparation which is 80 per cent homogeneous in the analytical ultracentrifuge. It has been found to contain 30 to 37 per cent RNA as judged by a variety of analytical techniques. Approximately 55 per cent of the weight of the material is protein and a further 4.5 per cent phospholipide. Electron micrographs of air-dried specimens of the purified preparation show the 74 S constituent to be flattened spheres with an average height of 180 A and an average diameter of approximately 280 A. The molecular weight of the 74 S particles is computed from sedimentation, viscosity, and partial specific volume data to be 4.5 million +/- 10 per cent in agreement with the value estimated from electron micrographs. The 74 S or microsomal component of pea epicotyls is rapidly aggregated in the presence of low concentrations of Mg ions or by somewhat higher concentrations of Ca or K salts. ATP on the contrary causes resolution of electrolyte-induced microsomal aggregates with simultaneous degradation of the particles to an ultracentrifugally inhomogeneous mixture of lower molecular weight materials.

Animals↗

PubMed1959

Comparative studies on the physical characteristics of the heritable haptoglobin groups of human serum.

Ultracentrifugal studies of the alpha(2)-proteins of normal human serum before and after the addition of hemoglobin have revealed three separate and clearly distinguishable patterns based on the three major serum haptoglobin groups. Isolation of the three haptoglobin hemoglobin complexes disclosed characteristic patterns for each group. The heterozygote was found to possess electrophoretic and ultracentrifugal components not seen in either homozygote. Separation of normal human serum, to which hemoglobin had been added, by conventional starch zone electrophoresis resulted in three characteristic patterns which also permitted the ready identification of the serum haptoglobin group. The haptoglobin hemoglobin complex from Group 1-1 had the fastest mobility and that of Group 2-2 the slowest. The heterozygote Group 2-1 had an intermediate mobility. Immunologic differences between the haptoglobin hemoglobin complexes of the three groups could not be detected. Some of the variations in the reported electrophoretic and ultracentrifugal patterns of normal human serum could be reasonably ascribed to the group variation of the haptoglobins in man. The physical studies imply that the proteins characteristic of the heterozygote differ in size and charge from those present in either of the two homozygotes and indicate that the genetic control of the synthesis of the serum haptoglobins is probably exceedingly complex.

Blood Proteins↗

PubMed1953

Axoplasmic proteins of the squid giant nerve fiber with particular reference to the fibrous protein.

1. Axoplasm of squid giant nerve fibers is examined with the ultracentrifuge and electrophoresis apparatus and several distinct components demonstrated. 2. One of these components, a protein called axon filaments, is isolated by fractional extraction followed by differential ultracentrifugation and redissolving in glycine solution. Axon filaments are monodisperse by ultracentrifugation. Their physical chemical properties have been studied. 3. The existence of a reversible transformation of axon filaments into a particle of lower molecular weight and lower asymmetry has been demonstrated.

Animals↗

PubMed1984

Inhibition of macrophage-mediated tumor cell destruction by oxidized lipoproteins.

Lipoproteins (LP), isolated from human sera by column chromatography and density ultracentrifugation, were tested for their ability to inhibit macrophage (M phi)-mediated tumor cell destruction. None of the LP subclasses isolated by ultracentrifugation inhibited M phi-mediated cytolysis. Chromatography on a Sephadex G-200 column, prior to or following ultracentrifugation, resulted in the isolation of very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) that prevented tumor cell destruction by M phi. High-density lipoprotein did not acquire the ability to inhibit M phi-mediated tumor cell killing under any condition. The acquisition of inhibitory activity by VLDL and LDL subclasses could be prevented by incorporation of EDTA and the bubbling of nitrogen gas into the chromatography buffer. These conditions inhibited the formation of lipid peroxides and thus prevented the formation of LP that inhibit M phi-mediated cytotoxicity. The mechanism by which oxidized LP prevents M phi from destroying tumor targets is not known. However, the mechanism does not appear to be related to a decrease in M phi viability.

Adult↗

PubMed1992

Biochemical and antigenic properties of the Campylobacter flagellar hook protein.

The flagellar filament-hook complex was removed from Campylobacter cells by shearing and was purified by differential solubilization and ultracentrifugation at pH 11 followed by cesium chloride buoyant density ultracentrifugation. Flagellar filaments were then dissociated in 0.2 M glycine-HCl (pH 2.2), and purified hooks were collected by ultracentrifugation. The hooks (105 by 24 nm) each displayed a conical protrusion at the proximal end, a concave cavity at the distal end, and helically arranged subunits. The apparent subunit molecular weight of the hook protein of seven of the eight Campylobacter strains studied was 92,500, while that of the other was 94,000. N-terminal amino acid analysis of the hook protein of two strains of Campylobacter coli and one strain of Campylobacter jejuni demonstrated that the first 15 residues were identical. Amino acid composition analysis showed that the Campylobacter hook protein contained 35.7% hydrophobic and 9.5% basic residues. Isoelectric focusing determined that the hook protein was acidic, with a pI of 4.9. Comparisons with the Salmonella and Caulobacter hook protein compositions and N-terminal amino acid sequences indicated that the Campylobacter protein was related, but more distantly than these two proteins were to each other. Immunochemical analysis with four different antisera and a panel of eight strains showed that serospecific epitopes were immunodominant. The Campylobacter hook proteins carried both cross-reactive and specific non-surface-exposed epitopes, as well as serospecific epitopes which were exposed on the surface of the assembled hook. One class of these surface-exposed hook epitopes was shared with serospecific flagellin epitopes and may involve posttranslational modification, while the second class of epitopes was hook specific and not shared with flagellin.

Amino Acid Sequence↗

PubMed1988

Effect of pepsin on partially purified pig gastric mucus and purified mucin.

Partially purified native-pig gastric mucus and purified pig gastric mucin, prepared by column chromatography and caesium chloride (CsCl) density-gradient ultracentrifugation, were subjected to pepsin digestion. The products of peptic digestion were chromatographed on Sepharose CL-2B, and fractions were assayed for carbohydrate by the periodic acid-Schiff reaction. The polymeric gastric mucin in the purified mucin samples was readily degraded by pepsin. In sharp contrast, the polymeric mucin in the partially purified mucus was relatively resistant to pepsin digestion. In 45 min, pepsin degraded 40% of the polymeric mucin in the purified samples, whereas it produced no significant degradation (less than 10%) in the partially purified mucus samples. In partially purified gastric mucus, treated with CsCl but not fractionated by ultracentrifugation, digestion with pepsin was also slow and incomplete. This showed that differences in susceptibility between partially purified and purified preparations are not due to the chaotropic effects of CsCl. In addition, the recombination of low-density nonmucin fractions in CsCl ultracentrifugation with the mucin also resisted pepsin digestion. Finally, we have shown that the low-density fractions in mucus exhibited a strong inhibitory effect of peptic activity in vitro. We conclude that under our experimental conditions, pepsin has little effect on partially purified mucus, and our findings indicate an inhibitor of peptic digestion is present in native gastric mucus. It is likely, but unproven, that this inhibitor is a noncovalently bound lipid present in the low-density fraction.

Animals↗

PubMed1990

Urinary excretion of apolipoproteins bound to HDL-like particles in rat nephrotic syndrome and their relation to plasma HDL.

Lipoprotein excretion was investigated in the urine of hyperlipidemic rats with nephrotic syndrome induced by aminonucleoside of puromycin. Incubation with phosphatidylcholine liposomes was employed to float apoproteins not bound to lipids, by ultracentrifugation at d = 1.21 g/ml. On ultracentrifugation of whole, untreated urine, the amount of protein floated was 6-fold greater in nephrotic vs. control rats and consisted mainly of HDL-like particles. Sodium dodecylsulfate-polyacrylamide gel electrophoresis showed that control urine contained apoproteins A-I, A-II, E and traces of C, whereas in the nephrotic urine apo-E and a large amount of apo-C was found. Addition of liposomes to the ultracentrifugal d = 1.21 g/ml infranate and reflotation at the same density resulted only in slight increment in the floated apoproteins, mainly C and A-I. Addition of liposomes to the whole urine and centrifugation at d = 1.21 g/ml also did not produce a greater yield in the floated apoproteins of control or nephrotic urine. These results indicated that the urine is virtually devoid of lipid-free apoproteins and those floated from both the nephrotic and control urine are complexed with lipids. The plasma VLDL + LDL fraction of nephrotic rats, though increased in quantity, did not differ markedly in composition from that of control rats. The HDL, approximately 3-fold elevated in nephrotic rats, were poorer in esterified cholesterol and richer in phospholipids. Relative to plasma HDL, the nephrotic urine HDL were protein-rich and phospholipid-poor and appeared to be larger in particle size as suggested by the lower estimated specific volume. The modified plasma HDL in nephrosis may have a pathophysiological implication.

Animals↗

PubMedDate not supplied

Lipoproteins in familial hyperalphalipoproteinemia.

Familial hyperalphalipoproteinemia is determined by a major gene and is characterized by high levels of high density lipoprotein cholesterol and longevity. To describe the plasma lipoproteins in this condition more completely, a kindred consisting of the proband, her affected father, add her two affected brothers was studied. Fasting plasmas were analyzed for lipoprotein lipids by combined preparative ultracentrifugal and precipitation methods. Levels of apolipoprotein A-1 and apolipoprotein A-11, the major apoproteins of high density lipoproteins, were assayed by radioimmunoassay. The flotation properties of very low density, low density and high density lipoprotein were determined by zonal ultracentrifugation, and the isolated high density lipoprotein subfractions were characterized according to their lipid and apoprotein compositions. Total cholesterol of all subjects was normal, but triglycerides were elevated (above the 90th percentile) in the two brothers. High density lipoprotein cholesterol ranged from 150 to 165 mg/dl in the proband and from 72 to 89 mg/dl in her relatives. Apolipoprotein A-1 was 318 mg/dl in the proband and 156 to 169 mg/dl in the siblings; respective apolipoprotein A-11 values were 67 and 82 to 83 mg/dl. The high density lipoprotein cholesterol and apolipoprotein A-1 and A-11 values for the relatives are above the 95th percentile for sex and age, while the levels of the proband are the highest recorded in our laboratories. On zonal ultracentrifugation, very low density lipoprotein and low density lipoprotein had normal flotation properties. High density lipoprotein was divisible into three populations, HDL2, HDL3L, and HDL3D (Sf(1,21,26 degrees C), 59, 2.9, and 1.7 respectively), each of which floated in its usual position. But HDL2 was grossly elevated, accounting for most of the rise in the high density lipoprotein fraction. The compositions of the high density lipoprotein fractions with respect to the major lipid and apoprotein classes did not differ from normal. Thus, in this kindred, high density lipoprotein was quantitatively rather than qualitatively unusual. It is of interest that hypertriglyceridemia and hyperalphalipoproteinemia coexisted in the siblings. These concurrent elevations differ from the expected reciprocal relationship between high density lipoprotein and very low density lipoprotein levels in plasma, and suggests that in some subject the two abnormalities may be independently transmitted.

Apolipoproteins↗

PubMedDate not supplied

Net mass transfer of cholesteryl esters from low density lipoproteins to high density lipoproteins in plasma from normolipidemic subjects.

Net mass transfer of lipids was measured in plasma from fasted, normolipidemic subjects. The plasma was incubated, and lipoproteins were subsequently separated by polyanion precipitation or density gradient ultracentrifugation. Total cholesterol, unesterified cholesterol, and triglycerides were measured in the isolated lipoprotein fractions. The rate of cholesterol esterification was measured simultaneously. All plasma samples showed an increase in high density lipoprotein (HDL) cholesteryl esters during 1-hour incubations. In most cases, this increase was higher than the cholesteryl ester formation in total plasma due to cholesterol esterification. Therefore, we concluded that a net mass transfer of cholesteryl esters occurred from the very low plus low density lipoprotein (VLDL + LDL) fractions to HDL in plasma from most of the subjects studied. Transfer of triglycerides occurred from VLDL + LDL to HDL in plasma from all subjects. The cholesteryl ester transfer (measured after 1 hour) is not related to the activity of cholesteryl ester transfer protein. Inhibition of cholesterol esterification did not change the direction of cholesteryl ester or triglyceride transfer. Ultracentrifugal separation of plasma lipoproteins revealed that both HDL and VLDL are acceptors of cholesteryl esters and that VLDL donates triglycerides to both LDL and HDL. Removal of VLDL from plasma by ultracentrifugation did not affect the cholesteryl ester transfer from LDL to HDL. We conclude that LDL may act as a donor of cholesteryl esters during incubation of normolipidemic plasma.

Adult↗

PubMedDate not supplied

Alteration of high density lipoprotein subfractions of nonhuman primates fed fish-oil diets. Selective lowering of HDL subfractions of intermediate size and density.

Two groups of adult male African green grivet monkeys (12 animals in each group) were fed atherogenic diets containing 40% of total calories as fat with half of the fat calories derived from lard or menhaden oil and 0.8 mg cholesterol/kcal for a period of 10 months to ascertain the effect of such diets on lipoprotein concentrations, composition, and distribution. After 8 months on this diet, the animals' lipoproteins were isolated from their plasma by ultracentrifugation and agarose column chromatography, and these were characterized chemically. Compared with the lard-fed group, the menhaden oil-fed animals had significantly lower total plasma cholesterol (decreases 33%), HDL cholesterol (decreases 33%) and apo A-I (decreases 30%) concentrations and LDL molecular weights (decreases 15%). Although the fish-oil diets resulted in an average similar reduction of LDL cholesterol concentrations (decreases 34%), the decrease was not statistically significant. The lipid and apoprotein compositions of plasma LDL and HDL were similar between the two groups of animals. The distribution of HDL subfractions was determined by gradient gel electrophoresis and density gradient ultracentrifugation. The fish-oil group had a significant reduction in protein (decreases 46%) of HDL subfractions of intermediate size (80 to 88 A) compared to the lard-fed group. By density gradient ultracentrifugation, there was a 35% to 40% lower concentration of protein in the d = 1.10-1.13 g/ml subfraction of fish-oil-fed monkeys. Thus, feeding fish oil to nonhuman primates results in a selective decrease in the concentration of HDL subfractions of intermediate size and density compared to lard-fed animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗