Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Elevated levels of lipoprotein(a) (Lp(a)) have been strongly correlated with the development of atherosclerosis in human populations. Lp(a) is distinguishable from low density lipoprotein by the presence of the unique protein component apolipoprotein(a) (apo(a)), which contains repeated domains that closely resemble that of plasminogen kringle IV. Using human embryonic kidney cells, we have expressed a recombinant form of apo(a) (r-apo(a)) containing 17 kringle IV-like domains. We have utilized this recombinant expression system to study the assembly of Lp(a) particles. We have demonstrated that Lp(a) particles containing r-apo(a) can be assembled extracellularly in plasma by covalent linkage to low density lipoprotein. Using site-directed mutagenesis, we have demonstrated that a cysteine residue present at position 4057 of the apo(a) protein (i.e., in the penultimate kringle IV repeat) mediates this covalent linkage. Using polymerase chain reaction amplification of liver apo(a) complementary DNA, we have demonstrated the presence of a polymorphism in apo(a) kringle IV type 10, which results in the substitution of a threonine for a methionine. Preliminary studies indicate that the presence of a threonine at this position may enhance the interaction of Lp(a) with lysine-Sepharose.
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PMID:Analysis of structure--function relationships in human apolipoprotein(a). 806 77

Incubation of high density lipoproteins (HDL) with 0.1-10 microM copper ions resulted in a decrease in tryptophan residues and a moderate diminution of lysine residues. Polymerization of apolipoprotein AI (apo A-I) was only observed for the highest concentration of Cu2+. A dose-dependent loss in lecithin cholesterol acyl-transferase (LCAT) activity was noted. Following incubation with 10 mM malondialdehyde, the physicochemical properties of HDL were more pronouncedly affected, in terms of lipid peroxidation products, relative electrophoretic mobility and percentages of intact tryptophan and lysine residues. Polymerization of apo A-I occurred after 40 min incubation, and a time-dependent loss of LCAT activation was noted. Since the deficiency in LCAT activation was observed in relatively mild conditions, when no perturbation of the physico-chemical properties of the particle could be shown, the determination of LCAT activity appears to be a sensitive test for HDL discrete modification.
Atherosclerosis 1993 Dec
PMID:Copper- and malondialdehyde-induced modification of high density lipoprotein and parallel loss of lecithin cholesterol acyltransferase activation. 814 45

Non-enzymatic protein glycosylation is the first stage of the reaction described by L.C. Maillard. When the reaction progresses beyond that stage the long half-life molecules are damaged by formation of intermolecular crosslinking. The recent discovery of pentosidine, a crosslink between lysine and arginine residues, has demonstrated that advanced Maillard reaction is accelerated in diabetic patients with severe complications. Moreover, high tissue and plasma levels of pentosidine have been found in uraemia. The formation of advanced Maillard end-products (AGE) in plasma proteins constitutes a source of cell stimulation which induces macrophages to secrete cytokines, interleukin-1 and tumoral necrosis factor. Similarly, endothelial cells are induced to increase the permeability and production of the procoagulant factor. These mechanisms are thought to play an important role in the pathogenesis of atherosclerosis, nephropathy and thromboembolic disorders of diabetes. The discovery of beneficial effects of amino-guanidine, an inhibitor of advanced Maillard reaction, in the prevention of experimental diabetic complications opens a new line of investigation and new hopes for diabetics.
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PMID:[Non-enzymatic glycosylation of proteins. Complications of diabetes mellitus, aging and kidney failure]. 824 84

Fifty-five serum samples from 99 Type 1 and 71 serum samples from 81 Type 2 diabetic patients (56% and 88%, respectively) brought about a 1.5-3.5-fold increase in total cholesterol content of cultured human intimal aortic cells. This atherogenic effect did not correlate with patient's age, diabetes duration or plasma lipid levels, and was mainly due to low density lipoprotein (LDL). Cholesterol accumulation in cells incubated with LDL highly correlated with that in cells exposed to corresponding patient's serum (r = 0.872 and r = 0.811, P < 0.0001, in Type 1 and Type 2 diabetic patients, respectively). In LDL from diabetic patients the sialic acid content was decreased by an average of 30% (P < 0.05), as compared with healthy subjects, and the fructosyl lysine content was increased by an average of 25% (P < 0.05). Atherogenic effect of patients' LDL significantly correlated with their fructosyl lysine content (P < 0.0001) and negatively correlated with sialic acid content (P < 0.0001). Two LDL fractions were further separated from the total LDL preparation by affinity chromatography on Ricinus communis agglutinin-agarose. The bound (desialylated) LDL fraction was characterized by an increased fructosyl lysine content and the altered neutral lipid and phospholipid composition, while non-bound (sialylated) LDL fraction did not differ from normal LDL. Desialylated, but not sialylated, LDL fraction induced massive cholesterol accumulation in cultured cells. In conclusion, the cholesterol accumulating effect of diabetic patients' blood sera is mainly related to atherogenic low density lipoprotein fraction, which is modified in various ways--by increased non-enzymatic glycosylation, desialylation and alterations in lipid composition. This multiple-modified LDL may contribute to the premature atherosclerosis development in diabetes mellitus.
Atherosclerosis 1993 Apr
PMID:Modified low density lipoprotein from diabetic patients causes cholesterol accumulation in human intimal aortic cells. 831 62

Nonenzymatic glycation of apolipoprotein B (apo B) is a post-secretory modification of low density lipoprotein (LDL) that affects its atherogenic potential and is implicated in the accelerated atherosclerosis associated with diabetes. To facilitate assessment of apo B glycation, we produced hybridomas secreting monoclonal antibodies specific for glycated apo B. SP 2/0 myeloma cells were fused with spleen cells from BALB/c mice immunized with purified apo B glycated non-reductively in vitro. Specificity of monoclonal antibodies secreted by the cloned cell line designated ES12 was demonstrated by immunoblotting and by direct ELISA, wherein the antibodies reacted with glycated epitopes residing in LDL but not in other plasma proteins, and did not react with nonglycated apo B or nonglycated LDL. Immunoblotting of human plasma with ES12 monoclonal antibody yielded an approx. 180,000 molecular weight component showing co-identity with apo B, indicating site specificity for glycated epitopes residing in apo B of the LDL complex and absence of reactivity with other nonenzymatically glycated plasma proteins. This reactivity of ES12 with the physiologic form of glycated apo B that occurs in vivo differs from properties of other antibodies raised against glycated lipoproteins, which recognized glycated residues only after reductive conversion to glucitol-lysine and which do not discriminate between different glycated proteins. In a competitive ELISA, mean concentration of glycated LDL, measured as apo B equivalents, in eight separate plasma samples was 19.7 +/- 1.9 micrograms/ml, representing 3.5 +/- 0.3% of total apo B. The ES12 monoclonal antibody allows specific determination of plasma glycated LDL concentrations, which may have diagnostic and pathogenetic importance.
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PMID:Immunologic detection and measurement of glycated apolipoprotein B with site specific monoclonal antibodies. 850 55

Nepsilon-(Carboxymethyl)lysine (CML) is an advanced glycation end product formed on protein by combined nonenzymatic glycation and oxidation (glycoxidation) reactions. We now report that CML is also formed during metal-catalyzed oxidation of polyunsaturated fatty acids in the presence of protein. During copper-catalyzed oxidation in vitro, the CML content of low density lipoprotein increased in concert with conjugated dienes but was independent of the presence of the Amadori compound, fructoselysine, on the protein. CML was also formed in a time-dependent manner in RNase incubated under aerobic conditions in phosphate buffer containing arachidonate or linoleate; only trace amounts of CML were formed from oleate. After 6 days of incubation the yield of CML in RNase from arachidonate was approximately 0.7 mmol/mol lysine compared with only 0.03 mmol/mol lysine for protein incubated under the same conditions with glucose. Glyoxal, a known precursor of CML, was also formed during incubation of RNase with arachidonate. These results suggest that lipid peroxidation, as well as glycoxidation, may be an important source of CML in tissue proteins in vivo and that CML may be a general marker of oxidative stress and long term damage to protein in aging, atherosclerosis, and diabetes.
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PMID:The advanced glycation end product, Nepsilon-(carboxymethyl)lysine, is a product of both lipid peroxidation and glycoxidation reactions. 862 37

Long-term incubation of proteins with glucose leads to the formation of advanced glycation end products (AGE). Recent immunological studies have suggested the potential role of AGE in atherosclerosis, aging, and diabetic complications. We previously prepared a monoclonal (6D12) as well as a polyclonal anti-AGE antibody and proposed the presence of a common AGE structure(s) that may act as a major immunochemical epitope [Horiuchi, S., Araki, N., & Morino, Y. (1991) J. Biol. Chem. 266, 7329-7332]. The purpose of the present study was to determine the major epitope. Amino acid analysis of AGE-proteins indicated that N(epsilon)-(carboxymethyl)lysine (CML) was a major modified lysine residue. Immunologic studies demonstrated the positive reaction of 6D12 not only to all CML-modified proteins tested, but also to BSA modified with several aldehydes known to generate a CML-protein adduct, and a linear correlation between the CML contents of CML-BSA and their immunoreactivity to 6D12 up to approximately 8 mol/mol of protein. Further experiments with CML analogs revealed that the epitope of 6D12 is a CML-protein adduct with an important carbonyl group. In contrast to 6D12, our polyclonal anti-AGE antibody showed a significant but much weaker immunoreactivity to CML-BSA, suggesting that the polyclonal antibody contains two populations, one reactive to CML (CML-PA) and the other unreactive to CML (Non-CML-PA). Non-CML-PA separated from CML-PA by CML-BSA affinity chromatography did not react with all CML-modified preparations, but retained its property to react commonly with AGE preparations obtained from proteins, lysine derivatives, and monoaminocarboxylic acids. Therefore, it is clear that a CML-protein adduct is a major immunological epitope in AGE structures, but there still exist other major epitope(s) expressed commonly in AGE-proteins.
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PMID:N (epsilon)-(carboxymethyl)lysine protein adduct is a major immunological epitope in proteins modified with advanced glycation end products of the Maillard reaction. 867 12

Stiffening of blood vessel walls occurs in the early stages of atherosclerosis, and this process is known to occur earlier in diabetic subjects. The effect could be due, in part, to glycation. Although collagen is responsible for ensuring the ultimate tensile strength of the tissue, elastin largely determines the compliance of the vessel wall in the normal physiological range of pressures and this appears to be closely matched to haemodynamic requirements. Changes in elastin are therefore likely to affect optimal function of the tissue. We have investigated the susceptibility of elastin to glycation and effects of glycation on its mechanical and physicochemical properties. We found that purified elastin and a collagen-elastin preparation from the porcine thoracic aorta rapidly incorporated glucose and ribose, the extent increasing linearly with increasing concentration and reaching a maximum after 7 days at 37 degrees C. Biochemical analysis showed that about one of the five lysines available per elastin monomer was glycated after 12 days incubation at a sugar concentration of 250 mmol/l. In long-term incubations glycation was associated with the appearance of the advanced glycation end products, the fluorescent cross-link pentosidine and the non-fluorescent putative cross-link NFC-1. In both purified elastin and the whole elastin-collagen matrix the slope of the force-extension curve increased significantly with glycation. The greatest increase in stiffness was observed in the elastin-collagen preparation after ribose incubation (250 mmol/l for 1 month), where the slope, at large strain, increased by 56 +/- 19% (mean +/- SD, n = 12). The diameter of the tissue at 1 N force also changed: for elastin there was an increase in length of approximately 5%, but for the elastin-collagen there was a decrease of similar magnitude indicating that glycation introduces differential strains within the fibrous protein matrix. Potentiometric titration demonstrated that glycation was associated both with loss of basic groups and shifts in pK of the acidic groups, which indicated changes in the environment of the charge groups due to conformational rearrangements. Changes in ion binding were dependent on pH, and were consistent with a reduction in effective anionic charge. Calcium binding to elastin was increased at acid pH, but decreased at higher pH. We suggest that these effects are not only due to changes in the charge profile, but also in the conformation of the molecule resulting from glycation of the charged lysine and arginine side-chain residues.
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PMID:Interactions of elastin and aorta with sugars in vitro and their effects on biochemical and physical properties. 889 99

N(epsilon)-(Carboxymethyl)lysine (CML), a major product of oxidative modification of glycated proteins, has been suggested to represent a general marker of oxidative stress and long-term damage to proteins in aging, atherosclerosis, and diabetes. To investigate the occurrence and distribution of CML in humans an antiserum specifically recognizing protein-bound CML was generated. The oxidative formation of CML from glycated proteins was reduced by lipoic acid, aminoguanidine, superoxide dismutase, catalase, and particularly vitamin E and desferrioxamine. Immunolocalization of CML in skin, lung, heart, kidney, intestine, intervertebral discs, and particularly in arteries provided evidence for an age-dependent increase in CML accumulation in distinct locations, and acceleration of this process in diabetes. Intense staining of the arterial wall and particularly the elastic membrane was found. High levels of CML modification were observed within atherosclerotic plaques and in foam cells. The preferential location of CML immunoreactivity in lesions may indicate the contribution of glycoxidation to the processes occurring in diabetes and aging. Additionally, we found increased CML content in serum proteins in diabetic patients. The strong dependence of CML formation on oxidative conditions together with the increased occurrence of CML in diabetic serum and tissue proteins suggest a role for CML as endogenous biomarker for oxidative damage.
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PMID:Increased accumulation of the glycoxidation product N(epsilon)-(carboxymethyl)lysine in human tissues in diabetes and aging. 902 79

Oxidative stress is implicated in the pathogenesis of numerous disease processes including diabetes mellitus, atherosclerosis, ischaemia reperfusion injury and rheumatoid arthritis. Chemical modification of amino acids in protein during lipid peroxidation results in the formation of lipoxidation products which may serve as indicators of oxidative stress in vivo. The focus of the studies described here was initially to identify chemical modifications of protein derived exclusively from lipids in order to assess the role of lipid peroxidative damage in the pathogenesis of disease. Malondialdehye (MDA) and 4-hydroxynonenal (HNE) are well characterized oxidation products of polyunsaturated fatty acids on low-density lipoprotein (LDL) and adducts of these compounds have been detected by immunological means in atherosclerotic plaque. Thus, we first developed gas chromatography-mass spectrometry assays for the Schiff base adduct of MDA to lysine, the lysine-MDA-lysine diimine cross-link and the Michael addition product of HNE to lysine. Using these assays, we showed that the concentrations of all three compounds increased significantly in LDL during metal-catalysed oxidation in vitro. The concentration of the advanced glycation end-product N epsilon-(carboxymethyl)lysine (CML) also increased during LDL oxidation, while that of its putative carbohydrate precursor the Amadori compound N epsilon-(1-deoxyfructose-1-yl)lysine did not change, demonstrating that CML is a marker of both glycoxidation and lipoxidation reactions. These results suggest that MDA and HNE adducts to lysine residues should serve as biomarkers of lipid modification resulting from lipid peroxidation reactions, while CML may serve as a biomarker of general oxidative stress resulting from both carbohydrate and lipid oxidation reactions.
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PMID:Lipoxidation products as biomarkers of oxidative damage to proteins during lipid peroxidation reactions. 904 7


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