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Diet, lipoproteins and cholesteryl ester transfer activity in hyperlipidaemic subjects
CLINICAL
NUTRITION
(1985) 4: lim3H
Diet, Lipoproteins and Cholesteryl Ester Transfer Activity in Hyperlipidaemic Subjects J.E.M.
Greener, D.M.L.H.A.
Jacobs, A.J. van Rozen and D. W. Erkelens
Dept. of Internal Medicine, University Hospital Catharijnesingel 3511 GV Utrechr, Netherlands. (Reprint requests to D.W.E.) ABSTRACT
In order to study the response of cholesteryl ester transfer activity (CETA) to alteration in diet in humans we carried out a longtidinal study in hyperlipidaemic patients. Five subjects, all hyperlipidaemic, were first given a low fat diet for 7 to 15 days and then a diet high in fat for 7 to 21 days. In four out of five patients both diets were low in energy. The plasma lipoprotein levels and CETA were measured daily. All patients responded on the low fat diet by a decrease in total cholesterol and total triglycerides. No response on the high fat diet was noticed except in the patient for whom the high fat diet was also high in
energy. In all patients the changes in CETA ran parallel to changes in (VLDL+LDL) cholesterol. It is concluded that diet induced changes in (VLDL+LDL) cholesterol are accompanied by similar changes in CETA in hyperlipidaemic subjects.
INTRODUCTION
METHODS Subjects
Cholesteryl ester transfer protein (CETP) occurs in plasma of man and various animals and catalyzes the transfer of cholesteryl esters, synthesized predominantly in HDL through the action of lecithin cholesterol acyltransferase (LCAT), between HDL, VLDL and LDL. Although the full physiological significance of CETP is not understood, its role in the distribution of cholesteryl esters among the lipoproteins is unequivocal [l-7]. In a recent report [8] we discussed the positive correlation of cholesteryl ester transfer activity in delipidated plasma with the (VLDL+LDL) cholesterol level in normal and hyperlipidemic subjects. Diets high in fat, saturated fat and cholesterol, cause significant elevations in plasma cholesterol, while diets low in these constituents cause a decrease [9-141 in cholesterol levels in man. In order to gain further knowledge on the role of CETP in the metabolism of lipoproteins we have studied cholesteryl ester transfer activity (CETA) longitudinally in hyperlipidemic patients during a low fat and high fat diet. Table 1
Five subjects, with different degrees of hyperlipidemia, were admitted during the entire period of study. Details on age, height, weight and plasma lipid concentration are given in Table 1. None of the subjects was taking medication known to effect plasma lipoprotein levels. All subjects had been prescribed “prudent” fat restricted diets previous to the study. Diets The effects of a low and high fat regimen on cholesteryl ester transfer activity and lipoprotein levels were investigated. The composition of the diets and the energy intake for the patients are given in Table 2. Subjects were given the low fat diet for 7 to 15 days, followed by the high fat diet for 7 to 21 days. Plasma lipoprotein measurements Ten ml of venous blood were collected daily after a 14h overnight fast, into disodium EDTA (1 mg/ml) tubes. The
Characteristics of the subjects studied. ___
Subject
Age
(yr)
1
50
Height (cm)
2
62
169 179
3 4 5
48 50 52
172 170 173
Weight (kg)
Plasma Cholesterol
Plasma triglycerides
mmol/l
mmolll
72.5
12.1
13.1
91.0 78.0 83.0 76.5
5.0 11.4 25.2 9.9
9.8 4.1 69.6 10.0
35
HDL. Cholesterol ____mmol/l -__-
0.65 0.57 0.57 0.30 0.51
-__-
36
DIET,
Table 2
LIPOPROTEINS
Composition
AND CHOLESTERYL
ESTER TRANSFER
ACTIVITY
IN HYPERLIPIDAEMIC
X’BJECTS
of diets low fat diet
Subject
daily energy intake
(KJ) 1 2-5
360 330-405
(energy 70)
fat
saturated fatty acids
23.2 13.0-25
34.7 36.0-40
monounsaturated fatty acids (70 of total fat) 38.8 3 1.o-34
polyunsaturated fatty acids
cholesterol
26.5 25-33.0
110 70-200
37.5 28.5
18.3 30.5
460 11 O-200
(mgiday)
high fat diet 1 2-5
550 330-405
40.0 50.0
44.2 40.5
plasma was separated by centrifitgation for 15 min at 3000 rpm. Plasma lipoproteins were separated by ultracentrifugation and heparin-McCl, precipitation [ 151. Cholesterol and triglyceride concentrations in whole plasma and in lipoprotein fractions were assayed by enzymatic procedures (Boehringer Mannheim Biochemicals, Kits nr 124 087 and 126 039). Protein was measured by the Biorad dye binding assay [16] using crystalline bovine serum albumin as protein standard.
in Figure 1. The low fat diet caused a reduction in plasma cholesterol levels in subjects one, two, four and five.
CholesteryI Ester Transfer Activity [3H]-CE-HDL was prepared by incubation of 6 ml freshly separated plasma with 100 pCi [3H] cholesterol at 37°C for 22h. At the conclusion of the incubation 15 ml red blood cells were added to remove radio labelled free cholesterol. The incubation was continued for another 1.5 h before reseparation the plasma. This procedure was repeated twice. The labelled and unlabelled lipoproteins were isolated by ultracentrifugation according to Redgrave [ 171. More than 80% of the recovered radioactivity was present in the cholesteryl ester. The transfer of cholesteryl ester was measured by the addition of delipidated patient plasma sample to donor and acceptor lipoproteins isolated from normal plasma. In short, mixtures of unlabelled LDL (500 mnol CE), labelled HDL (200 nmol CE) and defatted patient plasma samples were incubated for 16 h and 37°C. All incubations contained p-chloromercuriphenylsulfonate (PCMPS), an inhibitor of LCAT. LDL was then precipitated and the radioactivity in LDL was counted [8]. The transfer activity was calculated [ 171. Plasmas of one subject were measured in one run. Defatting was carried out in duplicate as were the subsequent incubations. The coefficient of variation of the assay was less than 10%.
RESULTS
The individual changes in the lipoprotein
levels are shown
24' t 201 '1 Ib-
L..
5
1
Fig. 1 Lipoprotein levels of subject l-5 during a low fat (I) and high fat (II) diet o----o total triglycerides, O----O total cholesterol, A----A LDL-cholesterol, A----A HDL-cholesterol.
U~INI~:AI.NI?XI l-ION Total cholesterol decreased, but LDL cholesterol levels increased in the subjects four and five when they consumed the low fat diet. HDL did not change significantly. When compared to the low fat diet the high fat diet hardly affected the lipoprotein levels during the admission with the exception of patient one. A large increase in the total triglycerides, total cholesterol, VLDL triglycerides and VLDL cholesterol was seen in this patient when the high fat diet was consumed. With the exception of patient one, the high fat diet was not significant different from the low fat diet in energy intake, fatty acid composition and daily cholesterol intake. Only the high fat diet with the altered fatty acid composition and the increased cholesterol and energy intake in patient one resulted in a significant increase in lipoprotein levels, Subject five showed a rapid response to the low fat diet resulting in a decrease in VLDL cholesterol and an increase in LDL cholesterol. These values stabilized during the hospital stay. The patient was followed for 3 weeks after leaving the hospital. A large increase in the lipid levels was seen within 3 days after discharge. The mean levels of CETA for all subjects are shown in Figure 2. In the same figure (VLDL+LDL) cholesterol levels are shown. In general the alteration in CETA runs VLDL.LDL)chol
I 161
parallel to the alteration in (VLDL+ LDL.) cholesterol. The effect of the diet on CETA was most clearly seen in subject one. On the low fat diet CETA declined to 52% of its original value at day six. On the high fat diet CETA increased again to 110% of the original levels at day 15. A gradual decline in CETA to 20% was also seen in patient four. An increase in CETA was measured m subject five after discharge. Subject two and three showed nonor (VIDI + lADI,) significant changes in CETA, cholesterol. DISCUSSION This study was undertaken to further characterize the possible physiological role of CETA in the distribution of cholesteryl ester among lipoproteins in man. Alterations in dietary composition were prescribed to affect the lipoprotein levels and to study the effect on CETA. Hyperlipidemic subjects were chosen to enhance the effect of diet. No other specific purpose was intended than lowering and raising lipoprotein levels. All diets except for the diet of subject one were low in energy. This may have been the reason for the altered response seen in patients two-five during the high fat diet. In agreement- with others we observed substantial interindividual variation in the response of the subjects to the low fat diet [lo-12-14, 18, 191. In three out of the five patients significant alterations in (VLDL + LDL) cholesterol were accompanied by parallel alterations in CETA. The present findings provide the first evidence for an alteration of CETA in response to dietary perturbation in man. In a recent report Fielding er J. [20] described the role of the composition of the lipoproteins in cholesteryl ester transport and noted a decreased affinity of (VLDL + LDL) for cholesteryl ester in dysbetalipoproteinemic hypercholesterolemia and some patients with hypertriglyceridemia. It is known that the composition of lipoproteins differ in various forms to hyperlipidemia [18-201. It would be of interest to investigate whether CETA plays a role in the formation of.lipoproteins with the altered composition. In the same article however, Fielding et ul. [20] did not find a difference in CETA in the various patients. This might be due to the difference in the method which was used. The increase (or decrease) in CETA in defatted plasma parallel with an increase (or decrease) in (VLDL + LDL) cholesterol during this longitudinal study is compatible with the positive correlation of CETA and (VLDL + LDL) cholesterol. The question arises whether this alteration in CETA is a general phenomenon also occurring in normolipidemic subjects. Another question which has to be answered is whether the alteration in CETA is due to a increase (decrease) in the total amount of circulation CETP or to an increased, (decreased) specific activity. A modulating role of the “inhibition protein” remains to be studied. Additional studies of J Iargcr
I-1-1-1-1-1 -1-,-1-.-d-,
0 3 -I-n-
6
9
12
15
0
3
6
9
12
15
Cl-U-
b-;-;-;-;2-& *I-II+
-,-,-,-,-,-,-,-,-,-*-I-I 3 6 9 --I--I-
days 12
15
I6
21
24
27
Fig. 2 Cholesteryl Ester Transfer Activity (CETA) and (VLDL+ LDL) cholesterol levels in plasma of subject 1-5. o----o CETA (nmoles GE/ml plasma/hr), O----O (VLDL+LDL)-cholesterol (mM).
34
41
37
38
DIET, LIPOPROTEINS AND CHOLESTERYL ESTER TRANSFER ACTIVITY IN HYl’ERLIl’IDAEMlC SUBJECTS
number of subjects with various hyperlipidemias and more uniform dietary regimens are needed to confirm our findings of a relationship between diet induced parallel alterations in (VLDL + LDL) cholesterol levels and CETA.
ACKNOWLEDGEMENTS This study was supported by the Dutch Heart Foundation 30.003) and by the Preventiefonds.
(NHS
REFERENCES [l] Glomset J A 1968 The plasma lecithin: cholesterolacyltransferase reaction. Journal of Lipid Research 9:155-167 (21 Pattnaik N M, Montes A, Hughes L B, Zilversmit D B 1978 Cholesteryl ester exchange protein in human plasma. Isolation and characterization. Biochimica et Biophysics Acta 530: 428-438 [3] Nestel P J, Reardon M F, Billington T 1979 In vivo transfer of cholesteryl esters from high density lipoproteins to very low density lipoproteins in man. Biochimica et Biophysics Acta 573: 403-407 [4] Fielding P E, Fielding C J 1980 A cholesteryl ester transfer complex in human plasma. Proceedings of the National Academy of Sciences of the USA 77: 3327-3330 [5] Marcel Y L, Vezina C, Teng B, Sniderman A 1980 Transfer of cholesterol ester between human high density lipoproteins and triglyceride-rich lipoproteins controlled by a plasma protein factor. Atherosclerosis 35: 127-133 [6] Barter P J, Hopkins C J, Calvert G D 1982 Transfers and exchanges of esterified cholesterol between plasma lipoproteins. Biochemistry Journal 208: l-7 [7] Ha Y C, Barter P J 1982 Differences in plasma cholesteryl ester transfer activity in sixteen vertebrate species. Comparative Biochemistry and Physiology 71: 265-269 [8] Groener J E M, Van Rozen A J, Erkelens D W 1984 Cholesteryl ester transfer activity. Localisation and role in distribution of cholesteryl ester among lipoproteins in man Atherosclerosis 50: 26 l-27 1 [9] Keys A, Anderson J T, Grande F 1957 Prediction of serum cholesterol responses of man to change in fats in the diet. Lancet 2: 959-966 [IO] Grundy S M 1975 Effects of polyunsaturated fats on lipid metabolism in patients with hypertriglyceridemia. Journal of Clinical Investigation 55: 269-282 [l l] Brewer H B 1981 The effect of low cholesterol, high polyunsaturated fat and low fat diets on plasma lipid and lipoprotein cholesterol levels in normal and
Submissiondate 2 Oct. 1984. Acceptedforpublication 2 NOV. 1984.
[12]
[13]
[14]
[15] [16]
[17]
(181
[19]
[20]
hypercholesterolemie subjects. American Journal of Clinical Nutrition 34: 1758-1763 Mistry P, Miller N E, Laker M, Hazard W R, Lewis B 1981 Individual variation in the effects of dietary cholesterol on plasma lipoproteins and cellular cholesterol homeostasin in man. Journal of Clinical Investigation 67: 493-502 Shephard J, Packard C J, Grundy S M, Yeshurun D, Grotto A M, Taunton 0 D 1980 Effects of saturated and polyunsaturated fat diets on the chemical composition and metabolism of low density lipoproteins in man. Journal of Lipid Research 21: 91-99 Vesby B, Gustafson I B, Boberg F, Karlstrom B, Lithe11 H, Werner L 1980 Substituting polyunsaturated for saturated fat as a single change in a Swedish diet: effects on serum lipoprotein metabolism and glucose tolerance in patients with hyperlipidemia. European Journal of Clinical Investigation 10: 193-202 Manual of Laboratory Operations. Vol 1 Lipid and lipoprotein analysis. Lipid Research Clin Program. Bradford M M 1976 A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of dyebinding. Analytical Biochemistry 72: 248-254 Redgrave T G, Roberts D C K, West C E 1977 Separation of plasma lipoproteins by density gradient ultracentrifugation. Analytical Biochemistry 65: 42-49 Fielding P E, Fielding C J, Have1 R J, Kane J P, Tun B 1983 Cholesterol net transport, esterification and transfer in human hyperlipidemic plasma. Journal of Clinical Investigation 71: 449-460 Slack J, Millo G L 1970 Anomalous low density lipoproteins in familial hypercholesterolemia. Clinica Chimica Acta 29: 15-25 Wilson D E, Lees R S 1972 Metabolic relationships among the plasma lipoproteins. Reciprocal changes in the concentration of very low and low density lipoproteins in man. Journal of Clinical Investigation 51: 1051-1057
NUTRITION
(1985) 4: lim3H
Diet, Lipoproteins and Cholesteryl Ester Transfer Activity in Hyperlipidaemic Subjects J.E.M.
Greener, D.M.L.H.A.
Jacobs, A.J. van Rozen and D. W. Erkelens
Dept. of Internal Medicine, University Hospital Catharijnesingel 3511 GV Utrechr, Netherlands. (Reprint requests to D.W.E.) ABSTRACT
In order to study the response of cholesteryl ester transfer activity (CETA) to alteration in diet in humans we carried out a longtidinal study in hyperlipidaemic patients. Five subjects, all hyperlipidaemic, were first given a low fat diet for 7 to 15 days and then a diet high in fat for 7 to 21 days. In four out of five patients both diets were low in energy. The plasma lipoprotein levels and CETA were measured daily. All patients responded on the low fat diet by a decrease in total cholesterol and total triglycerides. No response on the high fat diet was noticed except in the patient for whom the high fat diet was also high in
energy. In all patients the changes in CETA ran parallel to changes in (VLDL+LDL) cholesterol. It is concluded that diet induced changes in (VLDL+LDL) cholesterol are accompanied by similar changes in CETA in hyperlipidaemic subjects.
INTRODUCTION
METHODS Subjects
Cholesteryl ester transfer protein (CETP) occurs in plasma of man and various animals and catalyzes the transfer of cholesteryl esters, synthesized predominantly in HDL through the action of lecithin cholesterol acyltransferase (LCAT), between HDL, VLDL and LDL. Although the full physiological significance of CETP is not understood, its role in the distribution of cholesteryl esters among the lipoproteins is unequivocal [l-7]. In a recent report [8] we discussed the positive correlation of cholesteryl ester transfer activity in delipidated plasma with the (VLDL+LDL) cholesterol level in normal and hyperlipidemic subjects. Diets high in fat, saturated fat and cholesterol, cause significant elevations in plasma cholesterol, while diets low in these constituents cause a decrease [9-141 in cholesterol levels in man. In order to gain further knowledge on the role of CETP in the metabolism of lipoproteins we have studied cholesteryl ester transfer activity (CETA) longitudinally in hyperlipidemic patients during a low fat and high fat diet. Table 1
Five subjects, with different degrees of hyperlipidemia, were admitted during the entire period of study. Details on age, height, weight and plasma lipid concentration are given in Table 1. None of the subjects was taking medication known to effect plasma lipoprotein levels. All subjects had been prescribed “prudent” fat restricted diets previous to the study. Diets The effects of a low and high fat regimen on cholesteryl ester transfer activity and lipoprotein levels were investigated. The composition of the diets and the energy intake for the patients are given in Table 2. Subjects were given the low fat diet for 7 to 15 days, followed by the high fat diet for 7 to 21 days. Plasma lipoprotein measurements Ten ml of venous blood were collected daily after a 14h overnight fast, into disodium EDTA (1 mg/ml) tubes. The
Characteristics of the subjects studied. ___
Subject
Age
(yr)
1
50
Height (cm)
2
62
169 179
3 4 5
48 50 52
172 170 173
Weight (kg)
Plasma Cholesterol
Plasma triglycerides
mmol/l
mmolll
72.5
12.1
13.1
91.0 78.0 83.0 76.5
5.0 11.4 25.2 9.9
9.8 4.1 69.6 10.0
35
HDL. Cholesterol ____mmol/l -__-
0.65 0.57 0.57 0.30 0.51
-__-
36
DIET,
Table 2
LIPOPROTEINS
Composition
AND CHOLESTERYL
ESTER TRANSFER
ACTIVITY
IN HYPERLIPIDAEMIC
X’BJECTS
of diets low fat diet
Subject
daily energy intake
(KJ) 1 2-5
360 330-405
(energy 70)
fat
saturated fatty acids
23.2 13.0-25
34.7 36.0-40
monounsaturated fatty acids (70 of total fat) 38.8 3 1.o-34
polyunsaturated fatty acids
cholesterol
26.5 25-33.0
110 70-200
37.5 28.5
18.3 30.5
460 11 O-200
(mgiday)
high fat diet 1 2-5
550 330-405
40.0 50.0
44.2 40.5
plasma was separated by centrifitgation for 15 min at 3000 rpm. Plasma lipoproteins were separated by ultracentrifugation and heparin-McCl, precipitation [ 151. Cholesterol and triglyceride concentrations in whole plasma and in lipoprotein fractions were assayed by enzymatic procedures (Boehringer Mannheim Biochemicals, Kits nr 124 087 and 126 039). Protein was measured by the Biorad dye binding assay [16] using crystalline bovine serum albumin as protein standard.
in Figure 1. The low fat diet caused a reduction in plasma cholesterol levels in subjects one, two, four and five.
CholesteryI Ester Transfer Activity [3H]-CE-HDL was prepared by incubation of 6 ml freshly separated plasma with 100 pCi [3H] cholesterol at 37°C for 22h. At the conclusion of the incubation 15 ml red blood cells were added to remove radio labelled free cholesterol. The incubation was continued for another 1.5 h before reseparation the plasma. This procedure was repeated twice. The labelled and unlabelled lipoproteins were isolated by ultracentrifugation according to Redgrave [ 171. More than 80% of the recovered radioactivity was present in the cholesteryl ester. The transfer of cholesteryl ester was measured by the addition of delipidated patient plasma sample to donor and acceptor lipoproteins isolated from normal plasma. In short, mixtures of unlabelled LDL (500 mnol CE), labelled HDL (200 nmol CE) and defatted patient plasma samples were incubated for 16 h and 37°C. All incubations contained p-chloromercuriphenylsulfonate (PCMPS), an inhibitor of LCAT. LDL was then precipitated and the radioactivity in LDL was counted [8]. The transfer activity was calculated [ 171. Plasmas of one subject were measured in one run. Defatting was carried out in duplicate as were the subsequent incubations. The coefficient of variation of the assay was less than 10%.
RESULTS
The individual changes in the lipoprotein
levels are shown
24' t 201 '1 Ib-
L..
5
1
Fig. 1 Lipoprotein levels of subject l-5 during a low fat (I) and high fat (II) diet o----o total triglycerides, O----O total cholesterol, A----A LDL-cholesterol, A----A HDL-cholesterol.
U~INI~:AI.NI?XI l-ION Total cholesterol decreased, but LDL cholesterol levels increased in the subjects four and five when they consumed the low fat diet. HDL did not change significantly. When compared to the low fat diet the high fat diet hardly affected the lipoprotein levels during the admission with the exception of patient one. A large increase in the total triglycerides, total cholesterol, VLDL triglycerides and VLDL cholesterol was seen in this patient when the high fat diet was consumed. With the exception of patient one, the high fat diet was not significant different from the low fat diet in energy intake, fatty acid composition and daily cholesterol intake. Only the high fat diet with the altered fatty acid composition and the increased cholesterol and energy intake in patient one resulted in a significant increase in lipoprotein levels, Subject five showed a rapid response to the low fat diet resulting in a decrease in VLDL cholesterol and an increase in LDL cholesterol. These values stabilized during the hospital stay. The patient was followed for 3 weeks after leaving the hospital. A large increase in the lipid levels was seen within 3 days after discharge. The mean levels of CETA for all subjects are shown in Figure 2. In the same figure (VLDL+LDL) cholesterol levels are shown. In general the alteration in CETA runs VLDL.LDL)chol
I 161
parallel to the alteration in (VLDL+ LDL.) cholesterol. The effect of the diet on CETA was most clearly seen in subject one. On the low fat diet CETA declined to 52% of its original value at day six. On the high fat diet CETA increased again to 110% of the original levels at day 15. A gradual decline in CETA to 20% was also seen in patient four. An increase in CETA was measured m subject five after discharge. Subject two and three showed nonor (VIDI + lADI,) significant changes in CETA, cholesterol. DISCUSSION This study was undertaken to further characterize the possible physiological role of CETA in the distribution of cholesteryl ester among lipoproteins in man. Alterations in dietary composition were prescribed to affect the lipoprotein levels and to study the effect on CETA. Hyperlipidemic subjects were chosen to enhance the effect of diet. No other specific purpose was intended than lowering and raising lipoprotein levels. All diets except for the diet of subject one were low in energy. This may have been the reason for the altered response seen in patients two-five during the high fat diet. In agreement- with others we observed substantial interindividual variation in the response of the subjects to the low fat diet [lo-12-14, 18, 191. In three out of the five patients significant alterations in (VLDL + LDL) cholesterol were accompanied by parallel alterations in CETA. The present findings provide the first evidence for an alteration of CETA in response to dietary perturbation in man. In a recent report Fielding er J. [20] described the role of the composition of the lipoproteins in cholesteryl ester transport and noted a decreased affinity of (VLDL + LDL) for cholesteryl ester in dysbetalipoproteinemic hypercholesterolemia and some patients with hypertriglyceridemia. It is known that the composition of lipoproteins differ in various forms to hyperlipidemia [18-201. It would be of interest to investigate whether CETA plays a role in the formation of.lipoproteins with the altered composition. In the same article however, Fielding et ul. [20] did not find a difference in CETA in the various patients. This might be due to the difference in the method which was used. The increase (or decrease) in CETA in defatted plasma parallel with an increase (or decrease) in (VLDL + LDL) cholesterol during this longitudinal study is compatible with the positive correlation of CETA and (VLDL + LDL) cholesterol. The question arises whether this alteration in CETA is a general phenomenon also occurring in normolipidemic subjects. Another question which has to be answered is whether the alteration in CETA is due to a increase (decrease) in the total amount of circulation CETP or to an increased, (decreased) specific activity. A modulating role of the “inhibition protein” remains to be studied. Additional studies of J Iargcr
I-1-1-1-1-1 -1-,-1-.-d-,
0 3 -I-n-
6
9
12
15
0
3
6
9
12
15
Cl-U-
b-;-;-;-;2-& *I-II+
-,-,-,-,-,-,-,-,-,-*-I-I 3 6 9 --I--I-
days 12
15
I6
21
24
27
Fig. 2 Cholesteryl Ester Transfer Activity (CETA) and (VLDL+ LDL) cholesterol levels in plasma of subject 1-5. o----o CETA (nmoles GE/ml plasma/hr), O----O (VLDL+LDL)-cholesterol (mM).
34
41
37
38
DIET, LIPOPROTEINS AND CHOLESTERYL ESTER TRANSFER ACTIVITY IN HYl’ERLIl’IDAEMlC SUBJECTS
number of subjects with various hyperlipidemias and more uniform dietary regimens are needed to confirm our findings of a relationship between diet induced parallel alterations in (VLDL + LDL) cholesterol levels and CETA.
ACKNOWLEDGEMENTS This study was supported by the Dutch Heart Foundation 30.003) and by the Preventiefonds.
(NHS
REFERENCES [l] Glomset J A 1968 The plasma lecithin: cholesterolacyltransferase reaction. Journal of Lipid Research 9:155-167 (21 Pattnaik N M, Montes A, Hughes L B, Zilversmit D B 1978 Cholesteryl ester exchange protein in human plasma. Isolation and characterization. Biochimica et Biophysics Acta 530: 428-438 [3] Nestel P J, Reardon M F, Billington T 1979 In vivo transfer of cholesteryl esters from high density lipoproteins to very low density lipoproteins in man. Biochimica et Biophysics Acta 573: 403-407 [4] Fielding P E, Fielding C J 1980 A cholesteryl ester transfer complex in human plasma. Proceedings of the National Academy of Sciences of the USA 77: 3327-3330 [5] Marcel Y L, Vezina C, Teng B, Sniderman A 1980 Transfer of cholesterol ester between human high density lipoproteins and triglyceride-rich lipoproteins controlled by a plasma protein factor. Atherosclerosis 35: 127-133 [6] Barter P J, Hopkins C J, Calvert G D 1982 Transfers and exchanges of esterified cholesterol between plasma lipoproteins. Biochemistry Journal 208: l-7 [7] Ha Y C, Barter P J 1982 Differences in plasma cholesteryl ester transfer activity in sixteen vertebrate species. Comparative Biochemistry and Physiology 71: 265-269 [8] Groener J E M, Van Rozen A J, Erkelens D W 1984 Cholesteryl ester transfer activity. Localisation and role in distribution of cholesteryl ester among lipoproteins in man Atherosclerosis 50: 26 l-27 1 [9] Keys A, Anderson J T, Grande F 1957 Prediction of serum cholesterol responses of man to change in fats in the diet. Lancet 2: 959-966 [IO] Grundy S M 1975 Effects of polyunsaturated fats on lipid metabolism in patients with hypertriglyceridemia. Journal of Clinical Investigation 55: 269-282 [l l] Brewer H B 1981 The effect of low cholesterol, high polyunsaturated fat and low fat diets on plasma lipid and lipoprotein cholesterol levels in normal and
Submissiondate 2 Oct. 1984. Acceptedforpublication 2 NOV. 1984.
[12]
[13]
[14]
[15] [16]
[17]
(181
[19]
[20]
hypercholesterolemie subjects. American Journal of Clinical Nutrition 34: 1758-1763 Mistry P, Miller N E, Laker M, Hazard W R, Lewis B 1981 Individual variation in the effects of dietary cholesterol on plasma lipoproteins and cellular cholesterol homeostasin in man. Journal of Clinical Investigation 67: 493-502 Shephard J, Packard C J, Grundy S M, Yeshurun D, Grotto A M, Taunton 0 D 1980 Effects of saturated and polyunsaturated fat diets on the chemical composition and metabolism of low density lipoproteins in man. Journal of Lipid Research 21: 91-99 Vesby B, Gustafson I B, Boberg F, Karlstrom B, Lithe11 H, Werner L 1980 Substituting polyunsaturated for saturated fat as a single change in a Swedish diet: effects on serum lipoprotein metabolism and glucose tolerance in patients with hyperlipidemia. European Journal of Clinical Investigation 10: 193-202 Manual of Laboratory Operations. Vol 1 Lipid and lipoprotein analysis. Lipid Research Clin Program. Bradford M M 1976 A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of dyebinding. Analytical Biochemistry 72: 248-254 Redgrave T G, Roberts D C K, West C E 1977 Separation of plasma lipoproteins by density gradient ultracentrifugation. Analytical Biochemistry 65: 42-49 Fielding P E, Fielding C J, Have1 R J, Kane J P, Tun B 1983 Cholesterol net transport, esterification and transfer in human hyperlipidemic plasma. Journal of Clinical Investigation 71: 449-460 Slack J, Millo G L 1970 Anomalous low density lipoproteins in familial hypercholesterolemia. Clinica Chimica Acta 29: 15-25 Wilson D E, Lees R S 1972 Metabolic relationships among the plasma lipoproteins. Reciprocal changes in the concentration of very low and low density lipoproteins in man. Journal of Clinical Investigation 51: 1051-1057