Effect of diets on lipoprotein concentrations in heterozygous apolipoprotein E-deficient mice

Loss of apolipoprotein E synthesis causes increased serum cholesterol concentrations and the sensitivity to high-fat diet in mice. We analyzed the changes in lipoprotein and hepatic structures in apolipoprotein E-deficient mice kept on control diet and cholesterol diets. Basal cholesterolemia of heterozygous (+/-) mice (2.2+/-0.28 mmol/l) was the same compared to wild-type (+/+) mice (2.3+/-0.15 mmol/l), but was lower compared to homozygous (-/-) mice (10.3+/-1.40 mmol/l). In +/- mice, cholesterolemia rose to 3.2 mmol/l on cholesterol diet and to 9 mmol/l on cholate diet, to 3 mmol/l and 3.6 mmol/l in +/+ mice, and to 23.4 mmol/l and 70.5 mmol/l in -/- mice, respectively. While the ratio of cholesterol/triglyceride concentrations in VLDL, IDL and LDL fractions was not increased in +/- mice and +/+ mice, it was increased in -/- mice on control diet. On the cholesterol diet, this ratio rose and was dramatically increased by cholate diet in all groups of mice. Even though cholate supplementation increased cholesterol concentration, it led to substantial toxic changes in hepatic morphology of all animals. In conclusion, one functional apo E allele in +/- mice is effective in keeping serum cholesterol concentrations in normal range on a control diet, but not on the cholesterol and cholate diets.     

Effects of octreotide on lipid metabolism in acromegaly.

Hypertriglyceridemia is the most frequent modification of lipid metabolism observed in acromegaly. The somatostatin analog, octreotide (Sandostatin), widely used in the treatment of acromegaly, is able to produce a decrease in levels of growth hormone (GH), insulin, and Insulin-like Growth Factor 1 (IGF1). We have attempted to evaluate the influence of this treatment on the lipid status of acromegalic patients. Seventeen patients with active acromegaly were treated with octreotide, 100 to 500 micrograms/injection subcutaneously three times daily. The levels of fasting serum triglycerides (TG), total cholesterol, High Density Lipoprotein (HDL) cholesterol and IGF1, as well as mean plasma GH and insulin levels during a diurnal profile, were evaluated before and after three months of octreotide therapy. GH, insulin and IGF1 decreased by 61%, 42% and 36% respectively (p less than 0.05). Mean levels (+/- SEM) of TG and total cholesterol fell from 2.2 +/- 0.4 mmol/l to 1.6 +/- 0.3 mmol/l (p less than 0.05) and 6.4 +/- 0.39 mmol/l to 5.6 +/- 0.27 mmol/l (p greater than 0.05), respectively. There was no correlation between triglyceride decrease and hormonal changes or clinical status (BMI, age, sex). In conclusion, the administration of octreotide over a three month period to acromegalic patients is associated with a decrease in TG levels.     

Polymorphisms in ABCG5 and ABCG8 transporters and plasma cholesterol levels

ABCG5 and ABCG8 transporters play an important role in the absorption and excretion of sterols. Missence polymorphisms (Gln604Glu in the ABCG5 and Asp19His, Tyr54Cys, Thr400Lys, and Ala632Val in the ABCG8) in these genes have been described. In 131 males and 154 females whose dietary composition markedly changed and lipid parameters decreased over an 8-year follow-up study (total cholesterol decreased from 6.21+/-1.31 mmol/l in 1988 to 5.43+/-1.06 mmol/l in 1996), these polymorphisms were investigated using PCR. Plasma lipid levels and changes in plasma lipid levels were independent of the Gln604Glu polymorphism in ABCG5 and Asp19His and the Ala632Val polymorphisms in ABCG8. The Tyr54Cys polymorphism influenced the degree of reduction in total plasma cholesterol (delta -0.49 mmol/l in Tyr54 homozygotes vs. delta +0.12 mmol/l in Cys54 homozygotes, p<0.04) and LDL-cholesterol (delta -0.57 mmol/l in Tyr54 homozygotes vs. delta +0.04 mmol/l in Cys54 homozygotes, p<0.03) levels between 1988 and 1996 in females, but not in males. Male Thr400 homozygotes exhibited a greater decrease in total cholesterol (delta -0.90 mmol/l vs. delta -0.30 mmol/l, p<0.02) and LDL-cholesterol (delta -0.62 mmol/l vs. delta -0.19 mmol/l, p<0.04) than Lys400 carriers. No such association was observed in females. We conclude that Tyr54Cys and Thr400Lys variations in the ABCG8 gene may play a role in the genetic determination of plasma cholesterol levels and could possibly influence the gender-specific response of plasma cholesterol levels after dietary changes. These polymorphisms are of potential interest as genetic variants that may influence the lipid profile.     

Changes in plasma high-density lipoprotein cholesterol concentration after weight reduction in grossly obese subjects.

Changes in serum lipoproteins associated with weight loss were assessed in 13 grossly obese (relative weight 183%) patients who had participated in an outpatient semi-starvation diet consisting of liquid protein and carbohydrate. At the follow-up examination an average of six and a half months after the start of refeeding the mean weight loss was 16.1 +/- 4.5 kg or 15% of initial body weight. Significant increases in high-density lipoprotein (HDL) cholesterol of 0.16 +/- 0.05 mmol/l (6 +/- 2 mg/100 ml) and decreases in triglycerides (0.8 +/- 0.23 mmol/l; 73 +/- 20 mg/100 ml) and fasting blood sugar (0.6 +/- 0.22 mmol/l; 11 +/- 4 mg/100 ml) were observed. Changes in HDL cholesterol correlated significantly with changes in weight (r = 0.667) and percentage change in weight. The intercept of the regression equation relating HDL cholesterol to percentage change in weight was -7.3, indicating that a change in HDL cholesterol greater than zero required a weight loss of at least 7.3% of body weight. Thus, weight loss can significantly increase HDL cholesterol concentrations but a considerable amount of weight must be lost to produce a significant increase in HDL cholesterol concentration.     

Naringenin 7-O-cetyl ether as inhibitor of HMG-CoA reductase and modulator of plasma and hepatic lipids in high cholesterol-fed rats

Numerous studies in vitro have shown a close relationship between the chemical structure and biologic activity of flavonoids, whereby their basic structure is modified to increase or decrease their biologic activity. The effects of naringenin (1) and its synthetic derivative, naringenin 7-O-cetyl ether (2), on the lipid profile, the cholesterol-regulating enzyme activity and the excretion of sterol were compared in rats fed a high-cholesterol (1% wt/wt) diet. Either 1 or 2 was supplemented with a high-cholesterol diet for 6 weeks at a dose of 0.073 mmol/100g diet. The supplementation of 1 or 2 significantly lowered the levels (mean+/-SE) of the plasma total cholesterol (4.93+/-0.19 and 4.75+/-0.16 mmol/L vs 5.87+/-0.36 mmol/L, p<0.05) and hepatic triglyceride (0.12+/-0.01 and 0.11+/-0.01 mmol/g vs 0.18+/-0.01 mmol/g, p<0.05) and cholesterol (0.23+/-0.01 and 0.21+/-0.01 mmol/g vs 0.31+/-0.01 mmol/g, p<0.05) compared to those of the control. The compound 1 or 2 supplementation appeared to decrease the excretion of neutral sterols. The plasma HDL-cholesterol concentration and ratio of HDL to total cholesterol were significantly higher in 1 and 2 groups than in control group. Although the biological effect of 2 on inhibiting hepatic HMG-CoA reductase and ACAT activities was only significant compared to the control group, both compounds exhibited a significant hypocholesterolemic effect in rats fed a high-cholesterol diet. The results suggest that cholesterol biosynthesis and esterification were concomitantly reduced by 2, as indicated by the decreased HMG-CoA reductase and ACAT activities.     

The A-204C polymorphism in the cholesterol 7alpha-hydroxylase (CYP7A1) gene determines the cholesterolemia responsiveness to a high-fat diet

The aim of the study was to ascertain whether the A-204C polymorphism in the cholesterol 7 -hydroxylase (CYP7A1) gene plays any role in determining LDL-cholesterol (LDL-C) concentration responsiveness to a high-fat diet. The concentrations of total cholesterol and LDL-cholesterol were measured in eleven healthy men (age: 30.9+/-3.2 years; BMI: 24.9+/-2.7 kg/m(2);;) who were homozygous for either the -204A or -204C allele, after 3 weeks on a low-fat (LF) diet and 3 weeks on a high-fat (HF) diet. During both dietary regimens, the isocaloric amount of food was provided to volunteers; LF diet contained 22 % of energy as a fat and 2.2 mg of cholesterol/kg of body weight a day, HF diet 40 % of fat and 9.7 mg of cholesterol/kg of body weight a day. In six subjects homozygous for the -204C allele, the concentrations of cholesterol and LDL-cholesterol were significantly higher on HF than on LF diet (cholesterol: 4.62 vs. 4.00 mmol/l, p<0.05; LDL-C: 2.15 vs. 1.63 mmol/l, p<0.01, respectively); no significant change was observed in five subjects homozygous for the -204A allele. There were no other differences in lipid and lipoprotein-lipid concentrations. Therefore, the polymorphism in the cholesterol 7alpha-hydroxylase promotor region seems to be involved in the determination of cholesterol and LDL-C responsiveness to a dietary fat challenge.     

Lecithin:cholesterol acyltransferase deficiency increases atherosclerosis in the low density lipoprotein receptor and apolipoprotein E knockout mice.

The purpose of the present study was to test the hypothesis that lecithin:cholesterol acyltransferase (LCAT) deficiency would accelerate atherosclerosis development in low density lipoprotein (LDL) receptor (LDLr-/-) and apoE (apoE-/-) knockout mice. After 16 weeks of atherogenic diet (0.1% cholesterol, 10% calories from palm oil) consumption, LDLr-/- LCAT-/- double knockout mice, compared with LDLr-/- mice, had similar plasma concentrations of free (FC), esterified (EC), and apoB lipoprotein cholesterol, increased plasma concentrations of phospholipid and triglyceride, decreased HDL cholesterol, and 2-fold more aortic FC (142 +/- 28 versus 61 +/- 20 mg/g protein) and EC (102 +/- 27 versus 61+/- 27 mg/g). ApoE-/- LCAT-/- mice fed the atherogenic diet, compared with apoE-/- mice, had higher concentrations of plasma FC, EC, apoB lipoprotein cholesterol, and phospholipid, and significantly more aortic FC (149 +/- 62 versus 109 +/- 33 mg/g) and EC (101 +/- 23 versus 69 +/- 20 mg/g) than did the apoE-/- mice. LCAT deficiency resulted in a 12-fold increase in the ratio of saturated + monounsaturated to polyunsaturated cholesteryl esters in apoB lipoproteins in LDLr-/- mice and a 3-fold increase in the apoE-/- mice compared with their counterparts with active LCAT. We conclude that LCAT deficiency in LDLr-/- and apoE-/- mice fed an atherogenic diet resulted in increased aortic cholesterol deposition, likely due to a reduction in plasma HDL, an increased saturation of cholesteryl esters in apoB lipoproteins and, in the apoE-/- background, an increased plasma concentration of apoB lipoproteins.     

Short-term very low calorie diet reduces oxidative stress in obese type 2 diabetic patients

Oxidative stress is higher in obese diabetic than in non-diabetic subjects. This pilot study evaluates oxidative stress during short-term administration of a very low calorie diet in obese persons. Nine obese Type 2 diabetic patients (age 55+/-5 years, BMI 35.9+/-1.9 kg/m2) and nine obese non-diabetic control subjects (age 52+/-6 years, BMI 37.3+/-2.1 kg/m2) were treated by a very low calorie diet (600 kcal daily) during 8 days stay in the hospital. Serum cholesterol, triglycerides, non-esterified fatty acids (NEFA), beta-hydroxybutyrate (B-HB), ascorbic acid (AA), alpha-tocopherol (AT), plasma malondialdehyde (MDA) and superoxide dismutase (SOD) activity in erythrocytes were measured before and on day 3 and 8 of very low calorie diet administration. A decrease of serum cholesterol and triglyceride concentrations on day 8 was associated with a significant increase of NEFA (0.30+/-0.13 vs. 0.47+/-0.11 micromol/l, p<0.001) and B-HB (0.36+/-.13 vs. 2.23+/-1.00 mmol/l, p<0.001) in controls but only of B-HB (1.11+/-0.72 vs. 3.02+/-1.95 mmol/l, p<0.001) in diabetic patients. A significant decrease of plasma MDA and serum AT together with an increase of SOD activity and AA concentration (p<0.01) was observed in control persons, whereas an increase of SOD activity (p<0.01) was only found in diabetic patients after one week of the very low calorie diet. There was a significant correlation between NEFA or B-HB and SOD activity (p<0.01). We conclude that one week of a very low calorie diet administration decreases oxidative stress in obese non-diabetic but only partly in diabetic persons. Diabetes mellitus causes a greater resistance to the effects of a low calorie diet on oxidative stress.     

Relation of infant feeding to adult serum cholesterol concentration and death from ischaemic heart disease.

OBJECTIVE--To examine whether method of infant feeding is associated with adult serum lipid concentrations and mortality from ischaemic heart disease. DESIGN--Follow up study of men born during 1911-30. SETTING--Hertfordshire, England. SUBJECTS--5718 men, for 5471 of whom information on infant feeding had been recorded by health visitors and 1314 of whom had died. 485 of the men born during 1920-30 and still living in Hertfordshire who had blood lipid measurements. MAIN OUTCOME MEASURES--Death from ischaemic heart disease; serum cholesterol and apolipoprotein concentrations. RESULTS--474 men had died from ischaemic heart disease. Standardised mortality ratios were 97 (95% confidence interval 81 to 115) in men who had been breast fed and had not been weaned at 1 year, 79 (69 to 90) in breast fed men who had been weaned at 1 year, and 73 (59 to 89) in men who had been breast and bottle fed. Compared with men weaned before one year men not weaned had higher mean serum concentrations of total cholesterol (6.9 (not weaned) v 6.6 (weaned) mmol/l), low density lipoprotein cholesterol (5.0 v 4.6 mmol/l) and apolipoprotein B (1.14 v 1.08 g/l). Men who had been bottle fed also had a high standardised mortality ratio for ischaemic heart disease (95; 68 to 130) and high mean serum concentrations of total cholesterol (7.0 mmol/l), low density lipoprotein cholesterol (5.1 mmol/l), and apolipoprotein B (1.14 g/l). In all feeding groups serum apolipoprotein B concentrations were lower in men with higher birth weight and weight at 1 year. CONCLUSIONS--Age of weaning and method of infant feeding may influence adult serum low density lipoprotein cholesterol concentrations and mortality from ischaemic heart disease. Adult serum apolipoprotein B concentrations are related to growth in fetal life and infancy.     

Serum activity and hepatic secretion of lecithin:cholesterol acyltransferase in experimental hypothyroidism and hypercholesterolemia

Lecithin:cholesterol acyltransferase (LCAT), the major cholesterol esterifying enzyme in plasma, plays an important role in the removal of cholesterol from peripheral tissues. This study in rat focuses upon the effects of hypothyroidism and cholesterol feeding on serum activity and hepatic LCAT secretion. To obviate the effect that inclusion of high concentrations of cholesterol in the rat serum may have on the proteoliposome used in the assay of LCAT, very low and low density lipoproteins (VLDL and LDL) were removed by ultracentrifugation at d 1.063 g/ml. The molar esterification rate in the euthyroid VLDL + LDL-free serum was found to be 0.94 +/- 0.06 compared to 0.67 +/- 0.05 in hypothyroid rats and 1.56 +/- 0.14 in hypercholesterolemic rats. LCAT secretion by suspension cultures of hepatocytes from hypercholesterolemic rats was found to be significantly depressed when compared to that for euthyroid and hypothyroid animals. Secretion by hepatocytes from hypothyroid rats was depressed for the first 0-4 hr, but rapidly recovered. The depressed secretion of LCAT by hepatocytes from hypercholesterolemic rats correlates with the appearance in the media of apoE-rich, discoidal HDL. Discoidal HDL was six times more effective as a substrate for purified human LCAT than HDL from hypercholesterolemic serum, and twice as effective as serum and nascent HDL from euthyroid animals. It is concluded that the depressed LCAT activity in serum from hypothyroid rats is due to a depressed hepatic secretion of the enzyme and that the elevated serum activity of hypercholesterolemic rats may be related to a defect in LCAT clearance. Finally, the appearance of discoidal HDL in the medium upon culture of hepatocytes from hypercholesterolemic rats appears to be due to an inhibition of LCAT secretion by these cells.     

Impact on lipoprotein profile after long-term testosterone replacement in hypogonadal men.

Testosterone serum levels may influence the lipoprotein metabolism and possibly atherogenic risk. Our aim was to investigate the effects of long-term testosterone supplementation in hypogonadal men on multiple lipoprotein markers. 18 Hypogonadal men were studied before and after 3, 6, and 18 (n = 7) months of treatment with testosterone enanthate. During treatment, serum testosterone and estradiol increased, reaching normal levels (p < 0.0001 and 0.003, respectively). This was associated with a decrease in HDL cholesterol (from 1.40 +/- 0.10 mmol/l to 1.22 +/- 0.08 mmol/l, p < 0.001) after six months at the expense of HDL2 cholesterol (p < 0.01), as well as apoprotein A1 (from 139 +/- 3.4 mg/dl to 126 +/- 3.0 mg/dl, p < 0.005). Hepatic lipase activity increased (p < 0.05) and correlated positively with testosterone (r = 0.56, p < 0.02) and negatively with HDL cholesterol (r = - 0.58, p < 0.02). Total and LDL cholesterol, triglycerides, and apoprotein B did not increase. Among the seven patients who completed 18 months of treatment, triglycerides, total cholesterol, LDL and HDL cholesterol, as well as total cholesterol/HDL cholesterol ratio values did not differ from baseline while apoprotein A1 (p < 0.03) and HDL cholesterol (p < 0.015) remained decreased and hepatic lipase unchanged. Restoration of testosterone levels in hypogonadal men in this study did not reveal unfavorable changes based on total cholesterol/HDL cholesterol and LDL cholesterol/apoprotein B ratios, which are both atherogenic risk markers. Whether the changes in light of lipoprotein metabolism will adversely influence cardiovascular risk over time remains to be determined.     

Hepatic lipase and the clearing reaction: studies in euthyroid and hypothyroid subjects

Eight patients with primary hypothyroidism were compared to eleven euthyroid subjects with regard to the effects of a single i.v. dose of heparin on plasma lipoprotein concentrations (the "clearing reaction"). The hypothyroid patients were moderately hypercholesterolemic but had normal plasma triglyceride levels. Maximal activities of hepatic lipase (HL) and lipoprotein lipase (LPL) were lower in the hypothyroid than in the normal subjects. The hypothyroid patients demonstrated a significant decrease in total plasma cholesterol levels after heparin injection (from 8.36 +/- 0.70 mmol/l to 7.55 +/- 0.62 mmol/l, P less than 0.02). The maximal activity of HL after heparin was significantly correlated to the decrease in plasma cholesterol levels (P less than 0.05) and in LDL-cholesterol levels (P less than 0.01). The euthyroid subjects demonstrated a smaller decrease in total plasma cholesterol concentrations (from 5.53 +/- 0.31 to 5.08 +/- 0.28 mmol/l, P less than 0.05). In this group, the fall in cholesterol levels was not correlated to maximal HL activity. The reduction in plasma triglyceride levels after heparin was similar and significant (P less than 0.01) in both groups. These data support the view that decreased activity of HL contributes to the dyslipoproteinemia seen in hypothyroidism. They are also in accordance with the notion that HL is involved in the elimination of cholesterol from plasma.     

Cholesterol esterification by lecithin-cholesterol acyltransferase in A-I-free plasma

Lecithin-cholesterol acyltransferase (LCAT) mass, activity and endogenous cholesterol esterification rate were measured in plasma and apolipoprotein A-I-free (A-I-free) plasma from two normolipidemic and two hyperlipidemic subjects, and from a patient with Tangier disease. A-I was removed from plasma by an anti-A-I immunosorbent. LCAT activity was measured using an exogenous substrate. The plasma LCAT concentration of the four non-Tangier subjects was 4.63 +/- 0.64 micrograms/ml (mean +/- S.D.); means of 26 +/- 7% of total LCAT mass and 22 +/- 11% of plasma LCAT activity were found in their A-I-free plasma. The plasma LCAT concentration of the Tangier subject was 1.49 micrograms/ml. About 95% of LCAT mass and all LCAT activity were found in the A-I-free plasma. Thus, the LCAT mass (1.4 micrograms/ml) and activity (43.1 nmol/h per ml) in Tangier A-I-free plasma were not significantly different from that found in the four non-Tangier A-I-free plasmas (mass = 1.21 +/- 0.44 micrograms/ml; activity: 27.3 +/- 18.4 nmol/h per ml). Although the LCAT activity per unit mass of the enzyme in plasma and A-I-free plasma were comparable (24.9 +/- 2.8 vs. 22.8 +/- 7.8 nmol/h per micrograms LCAT, n = 5), the plasma cholesterol esterification rate of A-I-free plasma from all subjects was lower than that found in plasma (7.5 +/- 2.7 vs. 13.0 +/- 3.8 nmol/h per micrograms LCAT). In conclusion, although A-I-containing lipoproteins are the preferred substrates of LCAT, other LCAT substrates and cofactors are found in A-I-free plasma along with LCAT. Thus, non-A-I-containing particles can serve as physiological substrates for cholesterol esterification mediated by LCAT.     

The lecithin-cholesterol acyl transferase activity of rat intestinal lymph.

The lecithin-cholesterol acyl transferase (LCAT) activity in rat mesenteric lymph was examined as a possible source of chylomicron cholesteryl ester. Lymph activity was only 2-3% of rat serum activity. Removal of d less than 1.006 lipoproteins increased lymph LCAT activity, but only to 6-8% of that of serum. Relative to total cholesterol in the d greater than 1.08 g/ml fractions, lymph LCAT activity in lymph from fasting rats was less than serum, but in lymph from nonfasting rats the ratio LCAT/HDL-cholesterol reached levels greater than serum, suggesting a contribution of enzyme from the gut. Both LCAT activity and HDL concentration in mesenteric lymph increased during feeding. Subfractions of lymph that inhibited serum LCAT were: chylomicrons, VLDL, chylomicron lipid, VLDL apoprotein, and HDL apoprotein. In the rat, the low LCAT activity of mesenteric lymph was in part due to the low enzyme concentration present, and the activity was apparently lowered further by lipid-rich lipoproteins that inhibited the reaction. Enzyme inhibition due to the apoprotein fractions of lipoproteins is probably minor in the rat in vivo.     

Impact of the mass-reductive therapy with orlistat on 25-(OH)-D3 and PTH concentration in sera of obese, menopausal women

Epidemiological studies suggest a protective influence of obesity against postmenopausal bone loss. Lower risk of osteoporotic fractures was described in obese patients. However there were only a few studies which examined the effect of weight reduction on bone metabolism and results of these studies are controversial. The aim of the study was to evaluate the influence of weight reduction program using Orlistat on bone metabolism in perimenopausal women. Twenty obese women with simple obesity and without concomitant diseases (BMI 37.1 +/- 3.0 kg/m2, mean age 49.8 +/- 4.6 yrs) were enrolled into this study. The control group consisted of 20 healthy women (mean age 53.5 +/- 5.4 yrs, BMI 24.1 +/- 2.2 kg/m2). All patients have participated in a 3-month weight reduction therapy that consisted of: a 1000-1200 kcal/ day balanced diet (daily calcium consumption about 500mg), Orlistat 3 x 120mg a day and regular physical exercises. Before the weight reduction therapy and after 10% reduction of body weight, serum concentrations of PTH, 25-(OH)-D3, total calcium and phosphorus, total cholesterol were assessed. Dual energy x-ray absorptiometry (DEXA method) of lumbar spine and femoral neck, measuring BMD was performed once, after a 3-month weight reduction therapy using Lunar DPXL. All these measurements were performed only once in control subjects. After a 3-month weight reduction program in patients treated with Orlistat the mean weight loss was 11.6 +/- 5.1 kg which is 12.1 +/- 4.78 %. BMI decreased from 37.1 +/- 3.0 kg/m2 at baseline to 32.6 +/- 2.7 kg/m2 post-treatment. The body weight reduction resulted in significant decrease of body fat and total cholesterol concentration. In obese subjects serum concentration of 25-(OH)-D3 was significantly lower and serum concentration of PTH was significantly higher in comparison to healthy controls, both before and after weight reduction therapy. Serum concentration of PTH, 25-(OH)-D3, total calcium and phosphorus did not change significantly after therapy with Orlistat. Conclusion: 3-month weight reduction program using Orlistat did not influence significantly bone metabolism.     

Physical exercise modifies the effect of high cholesterol-sucrose feeding in the rat.

1. Adult male rats were fed a basic chow (less than 0.01% cholesterol) and the same diet modified to contain 0.2% cholesterol and 20% sucrose. 2. Cholesterol-sucrose diet increased the erythrocyte cholesterol and the liver cholesterol. This diet decreased the epididymal fat weight and the biliary cholesterol and it improved the micellar solubility of cholesterol in the bile. 3. Swimming daily for 1 h for 94 days modified the effect of cholesterol-sucrose feeding: it induced plasma lecithin-cholesterol acyltransferase (LCAT), it decreased erythrocyte cholesterol, plasma total and unesterified cholesterol, and adipose tissue phospholipids to a level even beyond that of the animals on the basic chow. These changes in lipid levels induced by exercise suggest an important role of LCAT in cholesterol transport. 4. Exercise did not effect micellar solubility of cholesterol in the bile probably because cholesterol biosynthesis was already suppressed by dietary cholesterol. 5. Exercise promotes cholesterol esterification and transport from the peripheral tissues to the liver not only on a low cholesterol diet (our previous reports) but also when feeding a diet high in cholesterol and sucrose.     

Leptin levels in obese children: effects of gender,weight reduction and androgens

Obesity in children is accompanied by increased circulating leptin concentrations. Girls have higher leptin concentrations than boys. The aim of our study was to compare serum leptin levels before and after a five-week weight reduction program and to study the relationship of leptin levels, serum total cholesterol, and androgens (testosterone, dehydroepiandrosterone, dehydroepiandrosterone sulphate) in 33 obese boys (age: 12.7+/-1.97 years, BMI: 30.46+/-4.54) and 66 obese girls (age: 12.7+/-2.51 years, BMI: 29.31+/-4.62). We found that serum leptin concentrations in obese children were significantly decreased after a weight reduction program (before 20.79+/-9.61 ng/ml, after 13.50+/-8.65 ng/ml in girls; before 12.25+/-10.09 ng/ml and after 5.18+/-3.56 ng/ml in boys, p<0.0001 in both genders). Leptin levels correlated positively with the body mass index before and after weight reduction. There was a positive association in obese boys and a negative one in obese girls between leptin levels and the WHR (waist to hip circumference ratio). Serum leptin also shows a strong relationship to fat distribution (p=0.02 in boys, p<0.0001 in girls). No significant correlation was found between leptin concentrations and total cholesterol or androgens. We confirmed that leptin is a sensitive parameter of body composition and weight reduction in obese children.     

The effect of weight loss on serum concentrations of FAS and tumour necrosis factor alpha in obese women

INTRODUCTION: Apoptosis can influence both adipose tissue mass and its distribution. The suprafamily of tumour necrosis factor (TNF) receptors stimulate apoptosis. The aim of the study was to assess serum concentrations of tumour necrosis factor alpha (TNF-alpha), TNF soluble receptors (sTNFRs) and FAS in obese subjects and to examine the changes in these parameters after weight loss. MATERIAL AND METHODS: The study group consisted of 23 obese women without additional disease aged 36.6 +/- 10.9 years. These were examined before and after three-month weight reduction treatment consisting of a diet of 1000 kcal/day and physical exercise. The control group comprised 17 lean healthy women aged 40.3 +/- 5.5 years. Blood samples were taken in the morning after an overnight fast. Serum concentrations of TNF-alpha, sTNFRs and FAS were measured by enzyme linked immunosorbent assay (ELISA). Serum concentrations of insulin were measured by RIA. Serum concentrations of glucose, total cholesterol, HDL cholesterol and triglycerides were measured by an enzymatic procedure. RESULTS: The mean weight loss over the three-month treatment was 11.4 +/- 3.1 kg. Following weight loss, serum TNF-alpha concentrations decreased significantly (7.3 +/- 3.0 vs. 5.4 +/- 1.6 pg/ml; p < 0.005) and concentrations of sTNFRs increased significantly (1222.6 +/- 211.8 vs. 1325.6 +/- 261.6 pg/ml; p < 0.05 and 1881.5 +/- 337.2 vs. 2057.4 +/- 358.7 pg/ml; p < 0.05 respectively). However, no changes in serum concentrations of FAS were observed after weight loss. CONCLUSION: We observed increased serum concentrations of TNF-alpha but not of FAS in obese women. The concentrations of TNF decreased and those of sTNFRs increased after weight loss. However, the weight reduction therapy did not change serum concentrations of FAS.     

Functional LCAT deficiency in human apolipoprotein A-I transgenic, SR-BI knockout mice

Reduction of plasma LCAT activity has been observed in several conditions in which the size of HDL particles is increased; however, the mechanism of this reduction remains elusive. We investigated the plasma activity, mass, and in vivo catabolism of LCAT and its association with HDL particles in human apolipoprotein A-I transgenic, scavenger receptor class B type I knockout (hA-ITg SR-BI-/-) mice. Compared with hA-ITg mice, hA-ITg SR-BI-/- mice had a 4-fold higher total plasma cholesterol concentration, which occurred predominantly in 13-18 nm diameter HDL particles, a significant reduction in plasma esterified cholesterol-total cholesterol (EC/TC) ratio, and significantly lower plasma LCAT activity, suggesting a decrease in LCAT protein. However, LCAT protein in plasma, hepatic mRNA for LCAT, and in vivo turnover of 35S-radiolabeled LCAT were similar in both genotypes of mice. HDL from hA-ITg SR-BI-/- mice was enriched in sphingomyelin (SM), relative to phosphatidylcholine, and had less associated [35S]LCAT radiolabel and endogenous LCAT activity compared with HDL from hA-ITg mice. We conclude that the decreased EC/TC ratio in the plasma of hA-ITg SR-BI-/- mice is attributed to a reduction in LCAT reactivity with SM-enriched HDL particles.     

Lipid peroxidation and total antioxidant status in patients with breast cancer

Oxidative stress is considered to be involved in the pathophysiology of all cancers. The aim of this study is to examine oxidative stress and antioxidant status in patients with breast cancer by evaluation of the serum levels of total antioxidant capacity (TAC) and lipid peroxidation products as malondialdehyde (MDA) and lipid hydroperoxide and to investigate the relationship between these parameters, oxidative stress and serum lipids and lipoproteins. In our study, serum TAC, MDA, lipid hydroperoxide, HDL-cholesterol, VLDL-cholesterol, LDL-cholesterol, total cholesterol, triacylglycerol (TAG), albumin and uric acid levels of 56-breast cancer patients in different clinical stages and 18 healthy women were determined. Significantly lower-levels of TAC were detected in patients with breast cancer in comparison to controls (2.01 +/- 0.01 mmol/l and 2.07 +/- 0.03 mmol/l, respectively, p < 0.05). Serum MDA levels of the patients were higher compared to the controls (3.64 +/- 0.25 microM and 2.72 +/- 0.22 microM, respectively, p < 0.05). No significant difference between lipid hydroperoxide levels of patients and controls was found (0.33 +/- 0.05 microM and 0.32 +/- 0.01 microM, respectively, p > 0.05). These data show that lower TAC and higher MDA levels i.e. increased oxidative stress may be related to breast cancer.