High Hydrostatic Pressure Induces a Lipid Phase Transition and Molecular Rearrangements in Low-Density Lipoprotein Nanoparticles

Macrophages derived from the human monocyte cell line THP-1 or isolated from the peritoneum of C3H/HEJ mice were incubated with oxidized low-density lipoprotein (LDL) and the total glutathione content (oxidized plus reduced) was measured. An initial depletion of glutathione was followed by an increase, such that after a period of 24 h the glutathione content has approximately doubled. This response required the oxidation of the lipid phase of the LDL molecule, since both native LDL and acetylated LDL had little effect on glutathione levels. The response of the cells to oxidized LDL was dependent on the extent of oxidative modification of the protein. It was also found that 4-hydroxynonenal had a similar effect on THP-1 cells, and we suggest that this or other aldehydes present in oxidized LDL causes the induction of glutathione synthesis in response to an initial oxidative stress and consequent glutathione depletion. In addition, we found that both cell types possess transferases and peroxidases capable of detoxifying aldehydes and peroxides. However, treatment of cells with oxidized LDL or 4-hydroxynonenal for a period of 24 h had no effect on the activities of these enzymes.

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Temperature and hydrostatic pressure-dependent pathways of low-density lipoprotein transport across microvascular barrier

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1992.262.1.h234 ◽

1992 ◽

Vol 262 (1) ◽

pp. H234-H245 ◽

Cited By ~ 3

Author(s):

J. C. Rutledge

Keyword(s):

Hydrostatic Pressure ◽

Water Flow ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Physical Nature ◽

Low Density ◽

Transport Pathway ◽

Transport Pathways ◽

Solute Permeability ◽

Ldl Transport

To further investigate the chemical and physical nature of low-density lipoprotein (LDL) transport pathways across intact microvessels, the effect of changes in temperature and microvessel hydrostatic pressure were measured in individually perfused postcapillary vessels within frog mesenteric vascular beds. LDL microvessel transport was measured at two microvessel temperature ranges (18-21 degrees C and 4-6 degrees C) and compared with transport of fluorescein, a small solute. Also, LDL transport was measured at a series of hydrostatic pressures (3-20 cmH2O) at microvessel temperatures of 18-21 degrees C and 4-6 degrees C to determine whether LDL transport was coupled to water flow, which would be evidence for hydraulic pathways of solute transport across the microvascular barrier. Quantitative fluorescence microscopy was employed to determine apparent solute permeability coefficients (Ps) under the various temperature and hydrostatic pressure conditions studied. The ratio of Ps fluorescein 18-21 degrees C/4-6 degrees C [1.6 +/- 0.3 (SD)] indicated that fluorescein was freely diffusible across the microvascular barrier through water-filled pathways as transport was inversely proportional to temperature-dependent changes in viscosity. The larger ratio for LDL (Ps LDL 18-21/4-6 degrees C = 9.5 +/- 8.1) than for fluorescein cannot be explained by LDL transport through fixed hydraulic pathways alone and suggests additional or alternate LDL transport mechanisms. In addition, Ps LDL increased as microvessel hydrostatic pressure increased at microvessel temperatures of 18-21 degrees C but not at 4-6 degrees C. Coupling of LDL transport to water flow at the high microvessel temperature range, but not at the low range, indicated the presence of a hydraulic transport pathway that was effectively absent when the microvessel was cooled. These results demonstrated a highly temperature and hydrostatic pressure-dependent LDL pathway that is consistent with a dynamic porous extracellular or transcellular mechanism of LDL transport.

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Comparative studies of the physical state of the lipid phase of normal and hypercholesterolemic very low density lipoprotein

Chemistry and Physics of Lipids ◽

10.1016/0009-3084(79)90022-7 ◽

1979 ◽

Vol 23 (1) ◽

pp. 49-62 ◽

Cited By ~ 2

Author(s):

Victoria A. Ploplis ◽

J.Kerry Thomas ◽

Francis J. Castellino

Keyword(s):

Comparative Studies ◽

Physical State ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Lipid Phase ◽

Very Low Density Lipoprotein ◽

Low Density

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Identification of lipoprotein X-like particles in rat plasma following Intralipid infusion

Canadian Journal of Biochemistry ◽

10.1139/o79-010 ◽

1979 ◽

Vol 57 (1) ◽

pp. 72-82 ◽

Cited By ~ 25

Author(s):

W. C. Breckenridge ◽

G. Kakis ◽

A. Kuksis

Keyword(s):

Bile Duct ◽

Free Cholesterol ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Rat Plasma ◽

Phospholipid Content ◽

Lipid Phase ◽

Low Density ◽

Cholesterol Acyl Transferase ◽

C Proteins

Fasting rats were infused with 10% Intralipid for 24 h (0.33 mL/h per 100 g body weight) and the plasma lipoproteins isolated and compared with those of fed animals and animals with bile duct ligatures as controls. There was a 6- to 10-fold increase in the free cholesterol and phospholipid content of total plasma in animals infused with Intralipid or with ligated bile ducts. The changes were largely restricted to the low density lipoproteins (d = 1.019–1.063 g/mL) where free cholesterol and phospholipid increased 30- to 60-fold compared with fed control animals. Hydroxylapatite chromatography of the low density lipoprotein fractions of both Intralipid-infused and bile duct ligated animals yielded a subfraction which was rich in free cholesterol (27%), phosphatidylcholine (66%), and protein (6%); the latter was composed primarily of albumin and apo C proteins. The electrophoretic mobility and polyanionic precipitation properties of the abnormal lipoprotein were indistinguishable from those of lipoprotein X isolated from the animals with bile duct ligatures. The albumin in the abnormal lipoprotein from both groups of experimental animals was detected immunochemically only after delipidation of the lipoprotein. Twice as much of the lipoprotein X accumulated in Intralipid-infused than in the bile duct ligated animals. On rechromatography of the residual low density lipoprotein other subfractions could be isolated which possessed lipid and protein proportions intermediate between those of the lipoprotein X and of normal rat plasma low density lipoprotein. The activity of lecithin cholesterol acyl transferase was increased twofold in the Intralipid-infused animals when compared with control animals, but it decreased by 50% in the animals with bile duct ligatures. It is concluded that the unusual lipoprotein X accumulates in the plasma of Intralipid-infused animals owing to incomplete clearance of the exogenous phospholipid, which mobilizes tissue cholesterol and in the form of vesicular particles serves as a lipid phase for apo C proteins. A comparable mechanism is suggested for the formation of lipoprotein X in the animals with bile duct ligature.

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Effect of temperature and phase transition on oxidation resistance of low density lipoprotein.

The Journal of Lipid Research ◽

10.1016/s0022-2275(20)39196-3 ◽

1996 ◽

Vol 36 (10) ◽

pp. 2113-2128

Author(s):

P Ramos ◽

S P Gieseg ◽

B Schuster ◽

H Esterbauer

Keyword(s):

Phase Transition ◽

Oxidation Resistance ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Effect Of Temperature ◽

Low Density

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Intralysosomal Accumulation of Colloidal Gold-Low Density Lipoprotein Conjugates in Chloroquine-Treated Fibroblasts

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011951x ◽

1985 ◽

Vol 43 ◽

pp. 546-547 ◽

Cited By ~ 1

Author(s):

Dean A. Handley ◽

Cynthia M. Arbeeny ◽

Larry D. Witte

Keyword(s):

Colloidal Gold ◽

Cultured Cells ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Coated Vesicle ◽

Low Density ◽

Cholesterol Esters ◽

Cultured Fibroblasts ◽

Surface Receptors ◽

Ldl Particles

Low density lipoproteins (LDL) are the major cholesterol carrying particles in the blood. Using cultured cells, it has been shown that LDL particles interact with specific surface receptors and are internalized via a coated pit-coated vesicle pathway for lysosomal catabolism. This (Pathway has been visualized using LDL labeled to ferritin or colloidal gold. It is now recognized that certain lysomotropic agents, such as chloroquine, inhibit lysosomal enzymes that degrade protein and cholesterol esters. By interrupting cholesterol ester hydrolysis, chloroquine treatment results in lysosomal accumulation of cholesterol esters from internalized LDL. Using LDL conjugated to colloidal gold, we have examined the ultrastructural effects of chloroquine on lipoprotein uptake by normal cultured fibroblasts.

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