The D allele of the angiotensin-converting enzyme gene contributes towards blood LDL-cholesterol levels and the presence of hypertension.

Coronary artery disease is a polygenic disease whose phenotypic manifestation depends on the interaction of the genetic background with a number of environmental factors. Recently, the gene coding for the angiotensin-converting enzyme (ACE) has been characterized and a deletion/insertion (D/I) polymorphism was defined. The prevalence of the three genotypes and their association with coronary artery disease (CAD) differ in different population groups. Mostly, the D allele was found as a significant risk factor for CAD, independently from other risk factors. In the present study, we determined the distribution of ACE alleles (D or I) in a cohort of healthy Israeli men and examined the correlation of the different genotypes with various CAD risk factors. We found LDL cholesterol levels to be highest in the DD genotype group, intermediate in the DI genotype group and lowest in the II genotype group. We also found higher blood pressure levels in subjects bearing the D allele compared to II homozygous subjects. In conclusion, it appears that the genetic influence of the D/I polymorphism on CAD manifests primarily through traditional risk factors.

Plasma antioxidants and lipid peroxidation in acute myocardial infarction and thrombolysis.

OBJECTIVES: The aim of this study was to investigate the balance between prooxidative and protective mechanisms in patients with acute myocardial infarction (AMI) throughout streptokinase (STK) therapy. METHODS: Patients who presented to coronary care unit within 3 hours of infarction were followed. Blood was collected before, 2 and 24 hours post STK. Plasma lipid peroxidation was analyzed by a free radical generating system (AAPH) and malondialdehyde equivalents and conjugated dienes quantitated. Plasma vitamins A, E and beta-carotene, were analyzed by HPLC. Patients' results were compared with those from age-matched, healthy control subjects. RESULTS: In 38 patients with AMI, baseline plasma antioxidant vitamin concentration was reduced compared with a healthy control group. Upon STK therapy, there was a significant drop in plasma vitamin E concentration. Successful reperfusion was followed by an increased plasma oxidizability. Plasma lipids were not significantly different in the AMI patients except for a lower HDL-cholesterol concentration. CONCLUSIONS: Patients with AMI showed a drop in plasma antioxidant vitamins. Upon thrombolysis, there was an enhanced lipid peroxidation. These alterations indicate the significance of free radical generation processes in reperfusion injury in AMI patients, and suggest the potential involvement of antioxidants in the management of AMI treated by thrombolysis.

[Effect of an extract containing esterol on plasma cholesterol and oxidants].

16 patients with hypercholesterolemia were treated with an extract of alpha-alpha leaves (esterol) while on a low-fat, low-cholesterol diet. Esterol is believed to inhibit the absorption of cholesterol and bile acids and may interfere with the absorption of essential nutrients. As oxidative modification of lipoproteins is required for the process of atherosclerosis, plasma antioxidant vitamins were followed. After 4 months of treatment, plasma cholesterol decreased by 10% from 282 to 250 mg/dl (p < 0.001) and LDL cholesterol by 13%, from 203 to 177 mg/dl (p < 0.001). Plasma antioxidant vitamins E, A and beta-carotene were unchanged. Thus, esterol has a cholesterol-lowering effect but apparently does not lower fat-soluble, plasma antioxidant vitamins. Both cholesterol-lowering and plasma antioxidant vitamins are important for the primary prevention of coronary artery disease in hypercholesterolemia.

Transient radiological and colonoscopic features of inflammatory bowel disease in a patient with severe Salmonella gastroenteritis.

Salmonella is the most commonly reported cause of food-borne outbreaks of gastroenteritis. We report a case of a severe and toxic form of enteritis caused by Salmonella enteritidis. Findings of colonoscopy, an upper G1 tract series, and small bowel follow-through were consistent with those of inflammatory bowel disease, but the enteritis was self-limited, and the patient recovered after supportive treatment only and has remained well.

HDL apolipoprotein A-I attenuates oxidative modification of low density lipoprotein: studies in transgenic mice.

Epidemiological evidence suggests that plasma high-density lipoprotein (HDL) is protective against coronary artery disease, whereas oxidatively modified low density lipoprotein is atherogenic. Human apolipoprotein A-I transgenic mice with overexpression of the human apolipoprotein A-I gene have increased plasma levels of apolipoprotein A-I and HDL-cholesterol. We analyzed LDL oxidation by determination of LDL associated malondialdehyde, peroxides and conjugated dienes. The present study demonstrates that HDL from both normal and human apolipoprotein A-I transgenic mice at similar concentrations inhibits LDL (protein concentration 500 mg/l) lipid peroxidation, but the effect of the human apolipoprotein A-I transgenic mice HDL was two-fold greater than that of HDL derived from normal mice. In addition, the electrophoretic mobility of oxidatively modified LDL was reduced about two-fold in the presence of human apolipoprotein A-I transgenic mice HDL than that obtained in the presence of normal mice HDL. We thus suggest that human apolipoprotein A-I possesses antioxidant properties which might neutralize LDL lipid peroxidation. This may underline the mechanism responsible for the lower prevalence of atherosclerosis in subjects with high plasma levels of HDL and apolipoprotein A-I.

Rhabdomyolysis complicating acute Epstein-Barr virus infection.

Infection with Epstein-Barr virus (EBV) is common and induces a broad spectrum of illness. In the majority of cases the disease manifests with typical signs of heterophile-positive infectious mononucleosis in which myalgia may be seen in up to 20% of cases. In this study, a case of rhabdomyolysis is reported occurring during the clinical course of an 18-year-old patient with infectious mononucleosis. This severe form of muscle involvement has been rarely associated with EBV infections. Five similar cases previously published in the English literature are also reviewed. The clinical implications of rhabdomyolysis and infectious mononucleosis are discussed.

Protective effect of low concentrations of oxidized low-density lipoprotein on endothelial cell integrity.

BACKGROUND: Increasing evidence suggests that oxidized low-density lipoprotein (LDL) is associated with the development of atherosclerosis in vivo. Because endothelial injury contributes to the development of the atherogenic , we investigated the efficacy of oxidized LDL on the integrity of human umbilical cord endothelial cells (HUVECs) by analyzing cytotoxicity and cell detachment. METHODS: The cellular integrity of cultured endothelial cells labeled with chromium-51. RESULTS: Low concentrations of oxidized LDL (25-50 micrograms protein/ml) induced morphological changes (cell elongation and formation of gaps in the cobblestone monolayer), decreased cellular cytotoxicity (by 13% compared with control). At higher concentrations of oxidized LDL (100 micrograms protein/ml), however, increases in cytotoxicity (by up to 70%) and cellular detachment (by up to 90%) were demonstrated. Native LDL, which was not oxidized in out cell system, did not induce any changes either in cytotoxicity or in cell detachment. The protective effect of low oxidized LDL concentrations against endothelial cell cytotoxicity and detachment was abolished by indomethacin (microM), indicating the involvement or prostaglandin synthesis in this protection. CONCLUSION: Our experiments suggest that oxidized LDL-induced alterations of endothelial cells involve a sequence of events leading from a non-cytotoxic protective stage to endothelial perturbation.

Pravastatin inhibits cellular cholesterol synthesis and increases low density lipoprotein receptor activity in macrophages: in vitro and in vivo studies.

1. Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme-A (HMG-CoA) inhibitor, is a highly selective inhibitor of hepatic cholesterol synthesis. We studied the in vivo and in vitro effects of pravastatin on macrophage cholesterol metabolism. 2. The effects of incubating pravastatin with human monocyte derived macrophages (HMDM), mouse peritoneal macrophages (MPM) and a J-774 A.1 macrophage-like cell line, on macrophage cholesterol synthesis, cellular degradation of native low density lipoprotein (LDL) and modified LDL, cholesterol efflux from these cells and the cholesterol esterification rate were determined. 3. Pravastatin was administered either as one 40 mg dose or 40 mg daily for 8 weeks to normocholesterolaemic and hypercholesterolaemic individuals. The effects on cholesterol synthesis and degradation in monocytes derived from these subjects were studied. 4. In vitro, pravastatin resulted in a dose-dependent inhibition of macrophage cholesterol synthesis. Cellular degradation of native LDL increased by 119% in the presence of 0.1 mg ml-1 pravastatin. Degradation of both acetyl LDL and oxidized LDL was unaffected. Small concentrations of pravastatin (up to 0.19 micrograms ml-1) increased the cellular cholesterol esterification rate after incubation with LDL, but higher concentrations resulted in an inhibition of the esterification. 5. Single dose pravastatin administration caused a reduction in cholesterol synthesis by the subjects own HMDM by 62% and 47% in normocholesterolaemic and hypercholesterolaemic individuals, respectively. Chronic administration resulted in a 55% inhibition of cholesterol synthesis and a 57% increase in LDL degradation. 6. The results indicate that the selective uptake of pravastatin shown for hepatocytes can be extended to macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of HDL apolipoprotein E in cellular cholesterol efflux: studies in apo E knockout transgenic mice.

The role of apo E in aspects of reverse cholesterol transport was studied in apolipoprotein E-deficient mice. These animals develop rampant atherosclerosis. The efflux of cholesterol from mouse peritoneal macrophages (MPM) was 40% lower when induced by high density lipoprotein (HDL) from apo E-deficient mice, compared to the effect of HDL from normal mice. On adding apo E to apo E-deficient HDL, cholesterol efflux from the macrophages increased by 35%, approaching the degree of efflux obtained with normal HDL. This HDL (normal or apo E-deficient)-induced cholesterol efflux was similar in peritoneal macrophages derived from both normal and apo E-deficient mice, suggesting that the HDL apo E rather than the macrophage apo E is responsible for the stimulation of cellular cholesterol efflux. On determining cholesterol efflux specifically from the macrophage plasma membrane, the level of efflux was similar for both HDL preparations, suggesting that apo E in HDL is important for cholesterol translocation to the plasma membrane, the initial step in reverse cholesterol transport. It is concluded that the enhanced atherosclerosis in apo E-deficient mice could be related, at least partly, to the impaired efflux of LDL derived cholesterol from macrophages of the arterial wall.

Increased plasma and lipoprotein lipid peroxidation in apo E-deficient mice.

Apo E-deficient mice which are highly atherogenic animals were used in order to study their plasma and lipoprotein lipid peroxidation in the absence or presence of oxidative stress. We have demonstrated that plasma from apo E knockout mice demonstrated increased lipid peroxidation both in the absence and in the presence of a free radical generating substance, 2,2-Azobis-(2-amidinopropane) hydrochloride (AAPH). Similarly, low and very low-density lipoprotein (LDL and VLDL) from apo E-deficient mice, but not their high-density lipoprotein (HDL), demonstrated increased lipid peroxidation. We suggest that in apo E-deficient mice, accelerated atherosclerosis is associated with increased lipid peroxidation of plasma, LDL and VLDL, as well as increased susceptibility of these lipoproteins to undergo lipid peroxidation under oxidative stress.

Low density lipoprotein isolated from patients with essential hypertension exhibits increased propensity for oxidation and enhanced uptake by macrophages: a possible role for angiotensin II.

In patients with essential hypertension, the increased risk for atherosclerosis is related not only to the blood pressure levels per se, but also to other, unknown, factors. Recent observations have indicated that oxidation of low density lipoprotein (LDL) and macrophage uptake of oxidized LDL are implicated in human atherosclerosis. We tested both the susceptibility of LDL, derived from hypertensive patients, to lipid peroxidation as well as its uptake by macrophages, in comparison with control LDL obtained from healthy subjects. The LDL that was derived from 25 patients with essential hypertension demonstrated increased propensity for lipid peroxidation with a 63%, 91% and 69% elevation in the content of the lipoprotein malondialdehyde, peroxides and conjugated dienes, respectively, in comparison with control LDL. Minimally modified LDL (MM-LDL) (prepared by 6 months' storage of the LDL at 4 degrees C) derived from the hypertensive patients also demonstrated increased lipid peroxidation with a 94%, 130% and 96% elevation in lipoprotein malondialdehyde, peroxides and conjugated dienes, respectively, compared with the control LDL. The susceptibility of the patients' LDL to lipid peroxidation decreased by 32% and 44% (measured as malondialdehyde) after 3 weeks of therapy with the angiotensin converting enzyme inhibitors captopril and enalapril, respectively, with no parallel reduction in the patients' blood pressure. The patients' LDL was shown to contain increased content of lipid peroxides and unsaturated fatty acids, which may explain its increased susceptibility to lipid peroxidation. In vitro experiments revealed that LDL can bind angiotensin II, and that angiotensin II has a stimulatory effect on copper-mediated oxidation of LDL, as well as on LDL degradation by macrophages. These results were secondary to cell-mediated oxidation of the LDL and to its cellular uptake via the scavenger receptor. We conclude that LDL derived from patients with essential hypertension is more susceptible to lipid peroxidation than control LDL, and this may be secondary to angiotensin II stimulation of LDL lipid peroxidation in these patients. Furthermore, this LDL demonstrates enhanced cellular uptake by macrophages in comparison with normal LDL which can also be related to angiotensin II-mediated LDL oxidation. Both these phenomena have been shown to be associated with accelerated atherosclerosis, and thus suggest a new mechanism for increased atherogenecity in hypertensive patients.

Lovastatin decreases plasma and platelet cholesterol levels and normalizes elevated platelet fluidity and aggregation in hypercholesterolemic patients.

The lipid composition of whole platelets and the fluidity of platelet membranes, as well as the sensitivity of the cell to aggregation, were studied in type IIA hypercholesterolemic human subjects before and after treatment with lovastatin. Fourteen patients with primary hypercholesterolemia having initial cholesterol levels of 383 +/- 52 mg/dL (mean +/- standard deviation) were studied and compared with 21 control subjects having cholesterol levels of 187 +/- 32 mg/dL. Lovastatin was administered orally at a starting dose of 40 mg daily. The dose was increased to 80 mg daily for eight patients who did not achieve the target cholesterol level of 200 mg/dL at 6 weeks. Serum cholesterol level was decreased by 37% following 20 weeks' administration of the drug. The fluidity of platelet membranes expressed in terms of the fluorescence anisotropy parameter was determined using the probe 1,6-diphenyl-1,3,5-hexatriene (DPH). When compared with platelets obtained from normocholesterolemic controls, platelets from hypercholesterolemic patients had a higher molar ratio of cholesterol to phospholipids ([C/PL] 0.86 +/- 0.15 v 0.57 +/- 0.06 for controls) and of phosphatidylcholine to sphingomyelin ([PC/SM] 2.64 +/- 0.87 v 2.00 +/- 0.15 for controls), enhanced fluidity (anisotropy parameter at 37 degrees C of 0.892 +/- 0.066 v 0.977 +/- 0.065 for controls), and a greater tendency to aggregate (aggregation of 84.2% +/- 6.3% v 78.5% +/- 7.6% for controls).(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced degradation of high density lipoprotein by peritoneal macrophages from nude mice is attenuated by interleukin-1.

Athymic nude mice are characterized by deficient cellular immunity due to almost complete absence of functional mature T-lymphocytes. Plasma HDL (the major cholesterol carrier in mice) cholesterol levels in nude mice were found to be reduced by 1.7 fold in comparison to control Balb/c mice. Cellular degradation of HDL by peritoneal macrophages (MPM) that were obtained from nude mice, was 2.5 fold greater in comparison to MPM obtained from Balb/c mice. Since nude mice lack cytokines that can affect lipid metabolism, intravenous administration of 10 micrograms/100g body weight of interleukin-1 (IL-1), tumor necrosis factor (TNF), or transforming growth factor (TGF) on HDL degradation by their PM, were investigated. IL-1 (but not TNF) reduced HDL (50 micrograms of protein/ml) cellular degradation from 810 +/- 34 to 350 +/- 12 ng/mg cell protein (p < 0.01) in nude mice. In control Balb/c mice, however, IL-1 as well as TNF enhanced macrophage degradation of HDL by 56% and 280%, respectively. TGF injection into nude mice (but not control mice) decreased HDL degradation by their MPM by 50%. We, thus, suggest that in nude mice the reduced plasma and HDL cholesterol levels are probably due to increased HDL degradation, which may be secondary to IL-1 and TGF deficiency.

Reduction of plasma cholesterol by lovastatin normalizes erythrocyte membrane fluidity in patients with severe hypercholesterolaemia.

The effect of lovastatin on erythrocyte membrane composition and fluidity was investigated in eight patients with severe hypercholesterolaemia (mean LDL-cholesterol of 7.2 mmol l-1). Lovastatin was administered at a dosage of 40-80 mg for 20 weeks and was discontinued for 5 weeks thereafter. Parallel to a 47% fall in plasma LDL cholesterol, there was a significant reduction (P < 0.01) in erythrocyte membrane cholesterol:phospholipid molar ratio, while erythrocyte membrane fluidity assessed by diphenylhexatriene (DPH) fluorescence polarization increased significantly (P < 0.01). Discontinuation of lovastatin resulted in the reversal of erythrocyte membrane composition and fluidity to pre-treatment values.

Lovastatin inhibits low-density lipoprotein oxidation and alters its fluidity and uptake by macrophages: in vitro and in vivo studies.

Under experimental conditions, oxidized low-density lipoprotein (Ox-LDL) may possess atherogenic properties, as is evidenced by its contribution to cholesterol accumulation in macrophages. LDL was oxidized in a cell-free system by predialysis of the lipoprotein against EDTA-free buffer and the addition of copper ions. Oxidation of LDL in the presence of lovastatin (10 to 1,000 mumol/L) resulted in a time- and dose-dependent reduction in thiobarbituric-acid-reactive substances (TBARS) concentration that was accompanied by increased LDL lysine-amino-group reactivity, in comparison with Ox-LDL produced in the absence of lovastatin. At 100 mumol/L, the drug reduced malondialdehyde concentration and increased amino-group reactivity by 24% and 42%, respectively. However, lovastatin's antioxidant effect was limited relative to other antioxidants, such as probucol and vitamin E. The fluidity of Ox-LDL was substantially reduced in comparison with native LDL. However, lovastatin inhibited this reduction in fluidity by 20%. Upon incubation of J-774 macrophage-like cell line with Ox-LDL, the lovastatin-treated Ox-LDL induced a reduction in the cellular cholesterol esterification rate in comparison with the effect of Ox-LDL that was produced in the absence of the drug. In four patients with hypercholesterolemia, the effect of lovastatin therapy (20 mg/d) on the sensitivity of their LDL to in vitro oxidation was studied. In all patients, Ox-LDL prepared from LDL obtained during lovastatin treatment demonstrated a reduced TBARS content, an increased trinitrobenzenesulfonic acid (TNBS) reactivity, an increased fluidity, and an impaired uptake by macrophages. These results were similar to those obtained by adding lovastatin in vitro.

Plasma lipoproteins and monocyte-macrophages in a peroxisome-deficient system: study of a patient with infantile refsum disease.

Hypocholesterolaemia in infantile Refsum disease (IRD) may link peroxisomes and lipoprotein metabolism. In our patient, plasma cholesterol levels were reduced to 26% and 29% of control in LDL and HDL fractions, respectively. Plasma apolipoproteins B-100 and A-I levels were 52% and 66% of controls, respectively. In the kindred, plasma cholesterol concentration was 61-73% of controls. The HDL-cholesterol/apo A-I ratios were: patient 0.12; kindred 0.17; controls 0.28. Analysis of the IRD patient's lipoprotein revealed compositional abnormalities in all fractions. The patient's LDL demonstrated a substantial reduction in its lipid-to-protein ratio. Alterations in plasma lipoproteins affect their interaction with macrophages. Upon incubation of the patient's LDL with J-774 macrophages, its cellular uptake, measured as cholesterol esterification rate, was only 66% of a control rate. The abnormal LDL of the IRD patient showed also only 25% of control susceptibility to in vitro oxidation. Studies of cellular cholesterol metabolism in the patient's monocyte-derived macrophages (MDM) showed 57% increased cholesterol esterification rate in comparison to normal MDM. The possible link between lipoprotein abnormalities and monocyte-macrophage cholesterol metabolism is discussed.