Enhancement of cholesteryl ester metabolism in cultured human monocyte-derived macrophages by verapamil

Yatsu, Frank M.; Alam, Rita; Alam, Syed Sartaj

doi:10.1016/0167-4889(85)90155-7

Cited by 29 publications

(5 citation statements)

References 22 publications

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“…The experiments were performed according to the methods described by Goldstein and Brown 27 with 100 ^ig protein/ml. The uptake procedure was slightly modified from that described by Yatsu et al 28 Cells were incubated at 37°C for different time intervals (see figure legends), then washed 10 times with 0.15 M NaCI. Cells were then dissolved in 0.1 M NaOH to assay for protein radioactivity.…”

Section: Determination Of Macrophage-assoclated Radioactivitymentioning

confidence: 99%

Presence of a modified low density lipoprotein in humans.

Avogaro¹,

Bon²,

Cazzolato³

1988

Arteriosclerosis

346

157

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Low density llpoproteins (LDL) collected from 18 fasting humans were subjected to ion exchange chromatography on DEAE Sepharose. By this procedure, a LDL subfraction was isolated with an electric charge more negative than the LDL bulk. This LDL appeared to be mainly characterized by low phospholipld content, high free cholesterol and protein content, low esterlfled/free cholesterol ratio, and a high content of conjugated dlenes, particularly of cholesterol esters. This subtraction, In an amount ranging from 5% to 20% of total LDL, was characterized by the presence of apo B-100 and protein aggregates that were reactive to anti-apo B monoclonal antibodies. Electron microscopy showed the more electronegative LDL to be heterogeneous in size with a tendency to aggregate. This LDL had low binding capacity with high affinity receptors of flbroblasts and low Immunoreactlvlty with the monoclonal antibodies that recognize the receptor binding domain of apo B. Finally, the Incubation of this LDL subtraction with cultured macrophages led to a higher Increase In cellular cholesterol In spite of a lower rate of uptake as compared to the LDL bulk and to acetyl-LDL. The more electronegative LDL subtraction that we Isolated for chemlcophyslcal behavior and conjugated dlene content may represent the peroxldized aliquot of human LDL (Arteriosclerosis 8:79-87, January/February 1988) N umerous studies have demonstrated that the plasma low density lipoproteins (LDL) are a heterogeneous collection of particles that vary in size, 1 density, 2 composition, 3 and electric charge. 4 The metabolic basis and physiological significance of LDL subtractions are unknown, although it now seems possible that some LDL forms are more atherogenic than others.5 Recently a series of in vitro studies proved that modified forms of LDL, being more negatively charged than native LDL, cause accumulation of cholesterol esters in cultured macrophages 6 -7 -8 and induce cytotoxicity in cultured endothelial cells.9 ' 10 The in vivo correlate of modified forms of LDL has not yet been identified although negatively charged LDL have been demonstrated in human atherosclerotic lesions.11 This paper reports data on the isolation and partial characterization of a subtraction of plasma LDL more electronegative than normal LDL. This was accomplished through separation of LDL collected from fasting subjects by ion exchange chromatography. Because modification of LDL mostly involves a free radical-initiated lipoprotein peroxidation, 91 10 ' 12 the extent of lipid peroxidation was also analyzed in the two LDL fractions obtained. Chemical and chemicophysical characterization of the more electronegative LDL, as well as its content of conjugated dienes of cholesterol and triglyceride free fatty acids, supports the From the Regional General Hospital, Regional Center for Atherosclerosis, Venice, Italy.Address for reprints: Pietro Avogaro, Regional General Hospital, 30100 Venice, Italy.This work was partly supported by Grant 84.02179.56 CNR, Consiglio Nazionale delle Ricerche, ...

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Section: Determination Of Macrophage-assoclated Radioactivitymentioning

confidence: 99%

Presence of a modified low density lipoprotein in humans.

Avogaro¹,

Bon²,

Cazzolato³

1988

Arteriosclerosis

346

157

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“…Degradation was determined according to the method of Yatsu et al 29 with 125 l-labeled acetyl-LDL in a 4-hour incubation period. Lipoproteins were labeled by the lODO-Bead method.…”

Section: Lipoprotein Degradationmentioning

confidence: 99%

Dysregulation of lipid metabolism in Tangier monocyte-derived macrophages.

et al. 1990

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“…They concluded that the nifedipine effect on cellular cholesterol might be partly due to increased cholesteryl ester hydrolysis. Another study 28 performed with cultured human monocyte-macrophages treated with verapamil, suggested that the C a + + antagonist leads to a more efficient intracellular processing of atherogenic lipoproteins.…”

Section: Amentioning

confidence: 99%

“…This procedure was carried out as described by Yatsu et al 28 with few modifications. Cells were incubated at 37°C for different time intervals (see figure legends), then washed five times with PBS/0.2% BSA (wt/vol) and five times with PBS.…”

Section: Determination Of Cell-associated Radioactivitymentioning

confidence: 99%