Coronary heart disease prevention task force.
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Cholesterol, HDL↗
Biomedical subjects
G Assmann
Publications and source records attributed to G Assmann.
Effects of lovastatin on progression of non-dilated and dilated coronary segments and on restenosis in patients after PTCA. The cholesterol lowering atherosclerosis PTCA trial (CLAPT).
OBJECTIVES: The Cholesterol Lowering Atherosclerosis PTCA Trial (CLAPT) is a prospective, randomized trial with blinded angiographic end-points to assess the effect of 2-year's treatment with lovastatin initiated 4 weeks prior to PTCA, compared to usual care on non-dilated coronary segments and on dilated coronary lesions in male patients with total cholesterol between 200 and 300 mg. dl(-1)who underwent elective PTCA. METHODS AND RESULTS: Two hundred and twenty six patients were randomized 4 weeks prior to PTCA to special care (diet plus lovastatin n=112) or usual care (diet; n=114). One hundred and ninety-nine patients underwent PTCA at baseline and were finally included in the study. Quantitative coronary angiographic assessment was performed on blinded cinefilms at baseline (PTCA) and repeated after 4 and 24 months in 91% and 81% of the patients. The primary end-point was a change in the mean segment diameter of non-dilated segments. The mean lovastatin dose was 33 mg. day(-1). Total- and LDL-cholesterol decreased by 21% and 29% in the special care group and by 7% and 11% in the usual care patients. After 2 years, the mean segment diameter of non-dilated segments decreased by 0.03 mm in the usual care group and 0.004 mm in the special care group (P=0.27). The decrease in the mean segment diameter of dilated lesions was 0.17 mm (usual care) and 0.06 mm (special care) (P=0.04) after 4 months; 0.16 mm (usual care) and 0. 002 mm (special care) after 24 months, respectively (P=0.05). In both groups, the mean segment diameter of dilated lesions increased between 4 and 24 months after PTCA compared to a decrease in mean segment diameter of non-dilated segments (P<0.05). Restenosis (>50% diameter stenosis at follow-up) occurred in 28.4% of usual care and 22.2% of special care patients (P=0.17). CONCLUSIONS: Lovastatin reduced the progression of dilated lesions in men with elective PTCA. Independent of treatment allocation, the dilated lesions regressed and the non-dilated segments progressed during the study follow-up. Four weeks of pre-treatment with lovastatin did not influence the rate of restenosis. Lovastatin had no statistically significant effect on non-dilated segments.
Angioplasty, Balloon, Coronary↗
D-dimers in relation to the severity of arteriosclerosis in patients with stable angina pectoris after myocardial infarction.
BACKGROUND: Plasma concentrations of D-dimers show the extent of intravascular fibrinolysis of cross-linked fibrin. Higher concentrations of D-dimers are found in the plasma of arteriosclerosis patients with increased fibrin metabolism. The present study was performed in order to investigate whether there is a relationship between the severity of arteriosclerosis and fibrinolytic activity indicated by plasma levels of D-dimer. METHODS: The study populations consisted of 1112 men and 299 women with stable angina pectoris, on average 36+/-5.6 days after a myocardial infarction, as well as 326 men and 138 women with no clinical signs of cardiovascular disease. In addition to cardiological and angiological examinations, the lipid status and levels of fibrinogen, plasma viscosity, F 1+2, plasminogen, plasminogen activator inhibitor-1, D-dimer, and C-reactive protein of the participants were determined. RESULTS: The plasma concentration of D-dimers increases with age, both in the group with coronary artery disease and in the control group, with the female gender showing consistently higher concentrations in both groups. D-dimers correlate with other parameters of the lipid and coagulation systems, which explains 32.0% and 39.2% of the variance in D-dimer values in men and women, respectively. A significant increase in the level of D-dimers can be found in participants with generalized arteriosclerosis, with a left ventricular ejection fraction </=40% as well as those with left-ventricular aneurysm. CONCLUSION: This study indicates that there is increased fibrinolytic activity in patients with severe arteriosclerosis. This finding gives further support to the hypothesis that D-dimer concentration is dependent on the amount of fibrin associated with arteriosclerotic thrombi. However, because of the low specificity and wide overlap of D-dimer values between patients and controls, enhanced D-dimer values are of limited relevance above and beyond other lipid metabolism risk indicators for coronary artery disease or coronary artery disease and peripheral arterial occlusive disease.
Adult↗
Effects of testosterone suppression in young men by the gonadotropin releasing hormone antagonist cetrorelix on plasma lipids, lipolytic enzymes, lipid transfer proteins, insulin, and leptin.
We investigated in a pilot study the effect of testosterone suppression on lipoprotein metabolism, insulin, and leptin in 10 men who were treated either with cetrorelix, an antagonist of gonadotropin releasing hormone, or with placebo (P). Group C + C (n = 4) was treated with 10 mg cetrorelix as daily subcutaneous injections for five days and with a subsequent injection of 60 mg cetrorelix depot. Group C + P (n = 3) received 10 mg cetrorelix as daily intramuscular injections for five days and a subsequent injection of placebo depot. Group P + P (n = 3) received placebo both as daily and depot injections. Treatment with cetrorelix reversibly suppressed testosterone to castrate levels for three weeks in group C + C and for one week in group C + P. Compared to baseline, treatment with cetrorelix increased serum levels of apolipoprotein (apo) A-I, HDL subclass LpA-I, insulin, and leptin. In the group P + P, treatment with placebo was not associated with any change of these parameters. Compared to baseline and group P + P, treatment with cetrorelix in groups C + C and C + P did not lead to considerable or consistent changes in the plasma activities of lecithin:cholesterol acyltransferase (LCAT), phospholipid transfer protein (PLTP), cholesteryl ester transfer protein (CETP), lipoprotein lipase, and hepatic lipase (HL). Only the pooled data of groups C + C and C + P unraveled small but statistically significant decreases of HL and CETP activities in response to cetrorelix. In conclusion, the small or absent effects of cetrorelix on LCAT, CETP, PLTP, LPL, and HL indicate that testosterone regulates HDL levels by other metabolic pathways. The increases of insulin and leptin in response to cetrorelix suggest that testosterone influences HDL metabolism also via obesity and insulin resistance. These effects, however, are rather in contrast to the HDL raising effect of suppressed testosterone.
Carrier Proteins↗
An ecological study of determinants of coronary heart disease rates: a comparison of Czech, Bavarian and Israeli men.
BACKGROUND: The large differences in cardiovascular disease rates between Eastern and Western Europe have largely developed over the last few decades, and are only partly explained by classical risk factors. This study was set up to identify other potential determinants of these differences. METHODS: This was an ecological study comparing random samples of men aged 45-64 years selected from three cities representing populations with different rates of cardiovascular mortality: Pardubice (Czech Republic), Augsburg (Bavaria, Germany), and Jerusalem (Israel). In total, 191 (response rate 70%), 153 (70%) and 162 (62%) men, respectively, participated. All centres followed the same study protocol. Lifestyle, anthropometry and biochemical risk factors were assessed by identical questionnaires, standardized medical examination, and central analyses of fasting blood samples. RESULTS: The mortality rates in the study populations, as well as the prevalence of coronary heart disease in study samples, were highest in Czech, intermediate in Bavarian and low in Israeli men. This pattern was replicated across the three samples by mean blood pressure (P < 0.001), cigarette smoking (not significant), triglycerides (P < 0.05), fibrinogen or D-dimer levels (P < 0.05). On the other hand, the prevalence of diabetes and obesity were similar; total and high density lipoprotein (HDL)-cholesterol, apolipoprotein B, lipoprotein (Lp(a)) and glucose did not differ between Czech and Bavarian men; and Czechs had particularly low levels of serum insulin and factor VIIc. Israelis had low fasting glucose and total cholesterol, as well as HDL-cholesterol levels and a high Lp(a) (each P < 0.001) compared with the two other samples. Striking differences were found for plasma homocysteine (10.5 in Czechs versus 8.9 mumol/l in Bavarians, P < 0.001) and for alpha-carotene (geometric mean in Czechs 16, Bavarians 21 and Israelis 30 micrograms/l), beta-carotene (60, 110 and 102 micrograms/l), and lycopene (84, 177 and 223 micrograms/l), respectively; all P-values < 0.001). Adjustment for obesity or smoking did not change these estimates. There were no differences in the levels of tocopherol and retinol. CONCLUSIONS: Czech men had high levels of blood pressure, triglycerides, fibrinogen and D-dimer but many other traditional risk factors, as well as indicators of metabolic disorders and vitamins A and E, did not differ between the study samples. The low levels of carotenoids and high concentrations of homocysteine in Czech men seem to reflect their low dietary intakes of fruit and vegetables. The results provide indirect support for the importance of dietary factors in the East-West morbidity and mortality divide.
Aged↗
Hypochromic red cells and reticulocyte haemglobin content as markers of iron-deficient erythropoiesis in patients undergoing chronic haemodialysis.
BACKGROUND: In patients on chronic haemodialysis, because of a non-specific increase in serum ferritin, iron deficiency may be overlooked leading to failure of erythropoietin treatment. A reticulocyte haemglobin content < 26 pg and a percentage of hypochromic red cells > 2.5 have been proposed as markers of iron-deficient erythropoiesis in such subjects, but it is unclear which parameter is superior. METHODS: We measured haematocrit, reticulocyte haemglobin content, ferritin and the percentage of hypochromic red cells over 10-150 days in 36 chronic haemodialysis patients in a university hospital. Transferrin saturation was also measured in a subset of 25 patients; iron deficiency was defined as a transferrin saturation < 15%. RESULTS: The diagnostic sensitivity and specificity of a reticulocyte haemoglobin content < 26 pg in detecting iron deficiency were 100% and 73% respectively, compared with 91% and 54% for a percentage of hypochromic red cells > 2.5. Paradoxical reticulocyte haemglobin concentrations occurred on follow-up in five patients receiving 4000 U erythropoietin per haemodialysis (HD). In three patients, reticulocyte haemglobin content exceeded 26 pg despite a persistent lack of iron. In a fourth, iron gluconate (62.5 mg i.v./HD) increased transferrin saturation to 27% and reduced the percentage of hypochromic red cells from 12 to 4, while reticulocyte haemglobin remained > 30 pg. In the final patient, iron gluconate increased transferrin saturation from 8 to 30% and reduced the percentage of hypochromic red cells from 40 to below 5, but reticulocyte haemglobin content remained < or = 26 pg throughout. CONCLUSIONS: The reticulocyte haemglobin content is superior to the percentage of hypochromic red cells in detecting iron deficiency in haemodialysis patients.
Adult↗
c-erbB-2/EGFR as dominant heterodimerization partners determine a motogenic phenotype in human breast cancer cells.
Separate mechanisms for oncogenesis and metastasis have been postulated. We show here that prolonged and invasive cell migration, a key mechanism in cancer metastasis, is linked to c-erbB-2 signaling. Cell lines with c-erbB-2 and EGFR expression and transphosphorylation activity display a high transendothelial invasiveness in an endothelial-extracellular matrix model mimicking a capillary vessel wall in vitro. Tyrosine-phosphorylated c-erbB-2 receptors and EGFR are localized predominantly in areas of the cell with high membrane extension activity. On the molecular level, there is a subtle cross talk between the transmembrane signaling molecule c-erbB-2 and the actin cytoskeleton at multiple levels, including the generation of the second messenger PIP2 and the mobilization of the actin-regulatory protein gelsolin. Our data strongly suggest that c-erbB-2, especially in a heterodimer with EGFR, is closely involved in signaling pathways, inducing alterations in cell morphology that are required for a human breast cancer cell to become motile and conceivably metastatic.
Breast Neoplasms↗
Strategies for the assessment of genetic coronary artery disease risk.
In atherosclerotic diseases, genetic factors have a substantial influence on the age of onset and the frequency and severity of clinical symptoms, as well as response to therapy. In myocardial infarctions occurring at young age, genetics may be the leading causative factor. Despite such a prominent role of genetics in the pathophysiology of atherosclerosis clinical risk assessment and therapeutic decision making are still based on classical risk factors. In this paper we analyse the reasons for the current lack of predictive power of genetics-based algorithms and we speculate why future developments might open the door to a role for genetics in the clinical management of atherosclerosis.
Coronary Disease↗
Systemic inflammatory parameters in patients with atherosclerosis of the coronary and peripheral arteries.
Plasma concentration of markers of inflammation are increased in patients with atherosclerosis. However, it is unclear whether the pattern and magnitude of this increase vary with the site and extent of disease. In 147 patients undergoing semiquantitative coronary angiography, we measured the acute-phase reactants C-reactive protein (CRP) or serum amyloid A (SAA); the proinflammatory cytokine interleukin 6 (IL-6); the active and total fractions of the anti-inflammatory cytokine transforming growth factor-beta (TGF-beta); the macrophage activation marker neopterin; and the infection marker procalcitonin. Compared with 62 patients without either coronary artery disease (CAD) or peripheral artery disease (PAD), 57 patients with CAD but no PAD showed greater median CRP (0. 4 versus 0.2 mg/dL, P=0.004) and IL-6 (3.8 versus 1.6 pg/mL, P=0. 007) levels and a lower level of active-TGF-beta (57 versus 100 ng/mL, P=0.038). Moreover, CRP, IL-6, and neopterin levels showed a positive and the active TGF-beta level a negative correlation with the extent of coronary atherosclerosis. Compared with these 57 patients with CAD alone, 15 patients with PAD and CAD had higher median levels of SAA (17 versus 7 mg/mL, P=0.008), IL-6 (12 versus 4 pg/mL, P=0.002), neopterin (14 versus 11 mg/dL, P=0.006), and total TGF-beta (11834 versus 6417 ng/L, P=0.001). However, these strong univariate associations of markers of inflammation and atherosclerosis were lost in multivariate analysis once age, sex, and high density lipoprotein cholesterol or fibrinogen were taken into account. Increased plasma levels of CRP, SAA, IL-6, TGF-beta, neopterin, and procalcitonin constitute an inflammatory signature of advanced atherosclerosis and are correlated with the extent of disease but do not provide discriminatory diagnostic power over and above established risk factors.
Acute-Phase Reaction↗
Depletion of pre beta 1LpA1 and LpA4 particles by mast cell chymase reduces cholesterol efflux from macrophage foam cells induced by plasma.
Exposure of the LpA1-containing particles present in HDL3 and plasma to a minimal degree of proteolysis by the neutral protease chymase from exocytosed rat mast cell granules (granule remnants) leads to a reduction in the high-affinity component of cholesterol efflux from macrophage foam cells. In this study, we demonstrate for the first time, a role for mast cell chymase in the depletion of the lipid-poor minor components of HDL that are specifically involved in reverse cholesterol transport as initial acceptors of cellular cholesterol. Thus, addition of proteolytically active granule remnants or human skin chymase to cholesterol-loaded macrophages of mouse or human origin incubated with human apoA1, ie, a system in which prebeta1LpA1 is generated, resulted in a sharp reduction in the high-affinity cholesterol efflux promoted by apoA1. As determined by nondenaturing 2-dimensional polyacrylamide gradient gel electrophoresis, the granule remnants effectively depleted the prebeta1LpA1, but not the alphaLpA1, in HDL3 and in plasma during incubation at 37 degrees C for <1 hour. Incubation of plasma with granule remnants for 1 hour also led to near disappearance of the LpA4-1 and LpA4-2 particles, but did not affect the distribution of the apoA2-containing lipoproteins present in the plasma. We conclude that the reduced ability of granule remnant-treated HDL3 and granule remnant-treated plasma to induce cholesterol efflux from macrophage foam cells is caused by selective depletion by mast cell chymase of quantitatively minor A1- and A4-containing subpopulations of HDL. Because these particles, ie, prebeta1LpA1 and LpA4, are efficient acceptors of cholesterol from cell surfaces, their depletion by mast cells may block the initiation of reverse cholesterol transport in vivo and thereby favor foam cell formation in the arterial intima, the site of atherogenesis.
Animals↗
Effects of a frequent apolipoprotein E isoform, ApoE4Freiburg (Leu28-->Pro), on lipoproteins and the prevalence of coronary artery disease in whites.
Different isoforms of apoE modulate the concentrations of plasma lipoproteins and the risk for atherosclerosis. A novel apoE isoform, apoE4Freiburg, was detected in plasma by isoelectric focusing because its isoelectric point is slightly more acidic than that of apoE4. ApoE4Freiburg results from a base exchange in the APOE4 gene that causes the replacement of a leucine by a proline at position 28. Analysis of the allelic frequencies in whites in southwestern Germany revealed that this isoform is frequent among control subjects (10:4264 alleles) and is even more frequent in patients with coronary artery disease (21:2874 alleles; P=0.004; adjusted odds ratio, 3.09; 95% confidence interval, 1.20 to 7.97). ApoE4Freiburg affects serum lipoproteins by lowering cholesterol, apoB, and apoA-I compared with apoE4 (P<0.05). Our 4 apoE4Freiburg homozygotes suffered from various phenotypes of hyperlipoproteinemia (types IIa, IIb, IV, and V). In vitro binding studies excluded a binding defect of apoE4Freiburg, and in vivo studies excluded an abnormal accumulation of chylomicron remnants. ApoE4Freiburg and apoE4 accumulated to a similar extent in triglyceride-rich lipoproteins. HDLs, however, contained about 40% less apoE4Freiburg than apoE4. In conclusion, our data indicate that apoE4Freiburg exerts its possible atherogenic properties by affecting the metabolism of triglyceride-rich lipoproteins and HDL.
Adult↗
Coronary heart disease: reducing the risk: the scientific background to primary and secondary prevention of coronary heart disease. A worldwide view. International Task force for the Prevention of Coronary Heart disease.
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Coronary Disease↗
Multiple dysfunctions of two apolipoprotein A-I variants, apoA-I(R160L)Oslo and apoA-I(P165R), that are associated with hypoalphalipoproteinemia in heterozygous carriers.
ApoA-I(R160L)Oslo and apoA-I(P165R) are naturally occurring apolipoprotein (apo) A-I variants that are associated with low HDL-cholesterol in heterozygous carriers. We characterized the capacity of these variants to bind lipid, to activate lecithin:cholesterol acyltransferase (LCAT), and to promote efflux of biosynthetic cholesterol from porcine aortic smooth muscle cells (SMCs) or exogenous cholesterol from lipid-loaded mouse peritoneal macrophages. During cholate dialysis, normal apoA-I and both variants associated completely with dipalmitoylphosphatidylcholine (DPPC) and formed rLpA-I of identical size. However, both apoA-I(P165R) and apoA-I(R160L)Oslo showed a reduced capacity to clear a turbid emulsion of dimyristoylphosphatidylcholine (DMPC). Compared to normal apoA-I, the LCAT-cofactor activity of apoA-I(P165R) and apoA-I(R160L)Oslo as defined by the ratio of Vmax to appKm was reduced significantly by 62% and 29%, respectively (here and throughout the text, the apparent Km is given as Michaelis-Menten kinetics do not take particle binding into account and therefore would result in errors with an interfacial enzyme such as LCAT; Vmax estimates are not affected by this error). ApoA-I/DPPC complexes induced biphasic cholesterol efflux from SMCs with a fast and a slow efflux component. Compared to rLpA-I reconstituted with wild type apoA-I, rLpA-I with apoA-I(P165R) or apoA-I(R160L)Oslo were significantly less effective in promoting cholesterol efflux from SMCs in incubations of 10 min duration but equally effective in incubations of 6 h duration. Lipid-free apoA-I did not induce efflux of biosynthetic cholesterol from SMCs but induced hydrolysis of cholesteryl esters and cholesterol efflux from acetyl-LDL-loaded mouse peritoneal macrophages. In the lipid-free form, both apoA-I variants promoted normal cholesterol efflux from murine peritoneal macrophages. We conclude that amino acid residues arginine 160 and proline 165 of apoA-I contribute to the formation of a domain that is very important for initial lipid binding and contributes to LCAT-activation and promotion of initial cholesterol efflux but not to the stabilization of preformed rLpA-I.
Animals↗
Phytanic acid is ligand and transcriptional activator of murine liver fatty acid binding protein.
Branched-chain phytanic acid is metabolized in liver peroxisomes. Sterol carrier protein 2/sterol carrier protein x (SCP2/SCPx) knockout mice, which develop a phenotype with a deficiency in phytanic acid degradation, accumulate dramatically high concentrations of this fatty acid in serum (Seedorf at al. 1998. Genes Dev. 12: 1189-1201) and liver. Concomitantly, a 6.9-fold induction of liver fatty acid binding protein (L-FABP) expression is observed in comparison to wild-type animals fed standard chow, possibly mediated by the peroxisome proliferator-activated receptor alpha (PPARalpha). Cytosolic transport of phytanic acid to either peroxisomal membranes or to the nucleus for activation of PPARalpha may be mediated by L-FABP, which gives rise to the question whether phytanic acid is a transactivator of this protein. Here we show first that phytanic acid binds to recombinant L-FABP with high affinity. Then the increase of the in vivo phytanic acid concentration by phytol feeding to mice results in a 4-fold induction of L-FABP expression in liver, which is in the order of that attained with bezafibrate, a known peroxisome proliferator. Finally to test in vitro whether this induction is conferred by phytanic acid, we cotransfected HepG2 cells with an expression plasmid for murine PPARalpha and a CAT-reporter gene with 176 bp of the murine L-FABP promoter, containing the peroxisome proliferator responsive element (PPRE). After incubation with phytanic acid, we observed a 3.2-fold induction of CAT expression. These findings, both in vivo and in vitro, demonstrate that phytanic acid is a transcriptional activator of L-FABP expression and that this effect is mediated via PPARalpha.
Animals↗
[Secondary coronary heart disease prevention by red wine?].
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Cholesterol, HDL↗
Overexpression and accumulation of apolipoprotein E as a cause of hypertriglyceridemia.
The molecular mechanisms of hypertriglyceridemia (HTG), a common lipid metabolic disorder in humans, often of genetic origin, are not well understood. In studying the effect of apolipoprotein (apo) E on the metabolism of triglyceride-rich lipoproteins, we found that expressing high plasma levels of human apoE3 in transgenic mice lacking endogenous mouse apoE caused HTG. These transgenic animals had 3-fold higher plasma triglyceride levels, higher very low density lipoproteins (VLDL), and lower high density lipoproteins than did nontransgenics. Removing one or both low density lipoprotein receptor alleles in the apoE3-overexpressing mice caused severe HTG (8-11-fold over nontransgenics) and increased VLDL and decreased low and high density lipoproteins, and apoE3-enriched VLDL were markedly depleted in apoC-II. At least two mechanisms could explain HTG associated with apoE3 overexpression: stimulated VLDL triglyceride production and impaired VLDL lipolysis. The apoE3 mice with HTG had a 50% increase in hepatic VLDL triglyceride production. Furthermore, overexpression of apoE (E2, E3, or E4) in cultured hepatocytes (McA-RH7777 cells) correlated positively with secretion of VLDL into the medium. However, apoE3 overexpression-associated HTG was only partially explained by VLDL overproduction, as lipoprotein lipase-mediated VLDL lipolysis was also decreased 20-86% depending on apoE3 levels, most likely by displacing or masking apoC-II on the particles. In human subjects, HTG correlated positively with increased VLDL triglyceride and plasma and VLDL apoE levels. However, plasma and VLDL apoE correlated negatively with VLDL apoC-II levels and lipoprotein lipase-mediated VLDL lipolysis. Thus, optimal expression of apoE is crucial for normal metabolism of triglyceride-rich lipoproteins, and overexpression and/or accumulation of apoE may contribute to HTG by stimulating VLDL triglyceride production and by impairing VLDL lipolysis. The apoE3-overexpressing mice will be useful for studying the pathophysiology of this disorder.
Animals↗
Low-dose expression of a human apolipoprotein E transgene in macrophages restores cholesterol efflux capacity of apolipoprotein E-deficient mouse plasma.
Apolipoprotein E- (apoE) deficient (E-/-) mice develop severe hyperlipidemia and diffuse atherosclerosis. Low-dose expression of a human apoE3 transgene in macrophages of apoE-deficient mice (E-/-hTgE+/0), which results in about 5% of wild-type apoE plasma levels, did not correct hyperlipidemia but significantly reduced the extent of atherosclerotic lesions. To investigate the contribution of apoE to reverse cholesterol transport, we compared plasmas of wild-type (E+/+), E-/-, and E-/-hTgE+/0 mice for the appearance of apoE-containing lipoproteins by electrophoresis and their capacity to take up and esterify 3H-labeled cholesterol from radiolabeled fibroblasts or J774 macrophages. Wild-type plasma displayed lipoproteins containing apoE that were the size of high density lipoprotein and that had either electrophoretic alpha or gamma mobilities. Similar particles were also present in E-/-hTgE+/0 plasma. Depending on incubation time, E-/- plasma released 48-74% less 3H-labeled cholesterol from fibroblasts than E+/+ plasma, whereas cholesterol efflux into E-/-hTgE+/0 plasma was only 11-25% lower than into E+/+ plasma. E-/-hTgE+/0 plasma also released 10% more 3H-labeled cholesterol from radiolabeled J774 macrophages than E-/- plasma. E+/+ and E-/-hTgE+/0 plasma each esterified significantly more cell-derived 3H-labeled cholesterol than E-/- plasma. Moreover, E-/- plasma accumulated much smaller proportions of fibroblast-derived 3H-labeled cholesterol in fractions with electrophoretic gamma and alpha mobility than E+/+ and E-/-hTgE+/0 plasma. Thus, low-dose expression of apoE in macrophages nearly restored the cholesterol efflux capacity of apoE-deficient plasma through the formation of apoE-containing particles, which efficiently take up cell-derived cholesterol, and through the increase of cholesterol esterification activity. Thus, macrophage-derived apoE may protect against atherosclerosis by increasing cholesterol efflux from arterial wall cells.
Animals↗
Isolation of blood-borne epithelium-derived c-erbB-2 oncoprotein-positive clustered cells from the peripheral blood of breast cancer patients.
Clinical studies including thousands of breast cancer patients have shown that c-erbB-2 is amplified and overexpressed in 20-30% of invasive human breast cancers and that it is associated with distant metastasis in specified patient subgroups. To isolate and characterize hematogeneously spreading c-erbB-2-positive epithelium-derived cells from the peripheral blood of breast cancer patients, a combined buoyant density gradient and immuno-magnetic separation method has been used. The method utilizes a biotinylated anti-cytokeratin monoclonal antibody (MAb) for capturing the epithelium-derived cells. The expression of c-erbB-2 by the captured cells was detected using an anti-c-erbB-2 rabbit antibody (21N) coupled to an anti-rabbit gold-labeled anti-body, whereby immunoenzymatic cytokeratin staining was performed using a silver-enhanced immunogold double staining protocol. In total, 29 of the 46 patients tested had either cytokeratin (24/29) or cytokeratin/c-erbB-2 (19/29) positive clustered cells in their peripheral blood. We thus report here the presence and the frequency of clone-specifically stained clustered cells in the peripheral blood of breast cancer patients. The frequency of cytokeratin/c-erbB2 double-positive clustered cells in the peripheral blood was on average 10 times higher than that of double-positive single cells. The numbers of cytokeratin/c-erbB-2 double-positive clustered cells were positively correlated with the stage of tumors. Results of in vitro motility experiments using single and clustered cells from primary breast cancer tissue strongly support the assumption that cytokeratin/c-erbB-2 double-positive clustered cells have a high potential for locomotion. We suggest that blood-borne epithelium-derived c-erbB-2-positive clustered cells are the possible precursor cells responsible for the formation of distant metastases and bone marrow micrometastases.
Animals↗