Relationship between High Density Lipoproteins and the Rate of In Vitro Serum Cholesterol Esterification

1978 ◽  
Vol 38 ◽  
pp. 72-76 ◽  
Author(s):  
Louis Soloff ◽  
K. G. Varma
Keyword(s):  
Serum Cholesterol ◽  
High Density ◽  
Cholesterol Esterification ◽  
High Density Lipoproteins

scholarly journals Evidence for the role of high density lipoproteins in mediating the antioxidant effect of estrogens

2000 ◽  
pp. 79-83 ◽  
Author(s):  
W Abplanalp ◽  
MD Scheiber ◽  
K Moon ◽  
B Kessel ◽  
JH Liu ◽  
...  
Keyword(s):  
Density Lipoprotein ◽  
Antioxidant Effect ◽  
High Density ◽  
In Vivo Studies ◽  
Ldl Oxidation ◽  
High Density Lipoproteins ◽  
Oh Groups

Estrogens possess strong antioxidant effects in vitro, but in vivo studies in humans have yielded conflicting results. Little is known regarding factors that mediate the antioxidant effect of estrogens in vivo. In this study the potential role of high density lipoprotein (HDL) was examined. The antioxidant effect of estradiol-17beta (E2) added to low density lipoprotein (LDL) was lost after dialysis. In contrast, the antioxidant effect of E2 added to HDL was conserved after dialysis, suggesting that E2 was bound to HDL. Binding of E2 to LDL increased after esterification (especially to long chain fatty acids). In the presence of HDL, an increased amount of E2 was transferred to LDL. E2-17 ester was as potent as E2 in preventing LDL oxidation in vitro, but 3,17-diesters were not as effective (E2=E2-17 ester>E2-3 ester>E2-3,17 diester). This was also supported by experiments which showed that estrogens with masked 3-OH groups were not effective as antioxidants. These studies provide evidence that HDL could facilitate the antioxidant effect of E2 through initial association, esterification and eventual transfer of E2 esters to LDL. Therefore it is critical that HDL peroxidation parameters be evaluated in subjects receiving estrogen replacement therapy.

Benefits of hypericin transport and delivery by low- and high-density lipoproteins to cancer cells: From in vitro to ex ovo

2019 ◽  
Vol 25 ◽  
pp. 214-224 ◽  
Author(s):  
Lenka Lenkavska ◽  
Ludmila Blascakova ◽  
Zuzana Jurasekova ◽  
Mariana Macajova ◽  
Boris Bilcik ◽  
...  
Keyword(s):  
Cancer Cells ◽  
High Density ◽  
High Density Lipoproteins

scholarly journals Serum Amyloid P Component Prevents High-Density Lipoprotein-Mediated Neutralization of Lipopolysaccharide

2000 ◽  
Vol 68 (9) ◽  
pp. 4954-4960 ◽  
Author(s):  
Carla J. C. de Haas ◽  
Miriam J. J. G. Poppelier ◽  
Kok P. M. van Kessel ◽  
Jos A. G. van Strijp
Keyword(s):  
Magnetic Beads ◽  
High Density ◽  
Serum Amyloid ◽  
High Density Lipoproteins ◽  
Amyloid P Component ◽  
Serum Amyloid P ◽  
Serum Amyloid P Component ◽  
Amyloid P ◽  
Lps Binding

ABSTRACT Lipopolysaccharide (LPS) is an amphipathic macromolecule that is highly aggregated in aqueous preparations. LPS-binding protein (LBP) catalyzes the transfer of single LPS molecules, segregated from an LPS aggregate, to high-density lipoproteins (HDL), which results in the neutralization of LPS. When fluorescein isothiocyanate-labeled LPS (FITC-LPS) is used, this transfer of LPS monomers to HDL can be measured as an increase in fluorescence due to dequenching of FITC-LPS. Recently, serum amyloid P component (SAP) was shown to neutralize LPS in vitro, although only in the presence of low concentrations of LBP. In this study, we show that SAP prevented HDL-mediated dequenching of FITC-LPS, even in the presence of high concentrations of LBP. Human bactericidal/permeability-increasing protein (BPI), a very potent LPS-binding and -neutralizing protein, also prevented HDL-mediated dequenching of FITC-LPS. Furthermore, SAP inhibited HDL-mediated neutralization of both rough and smooth LPS in a chemiluminescence assay quantifying the LPS-induced priming of neutrophils in human blood. SAP bound both isolated HDL and HDL in serum. Using HDL-coated magnetic beads prebound with SAP, we demonstrated that HDL-bound SAP prevented the binding of LPS to HDL. We suggest that SAP, by preventing LPS binding to HDL, plays a regulatory role, balancing the amount of LPS that, via HDL, is directed to the adrenal glands.

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