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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rabbits were fed an atherogenic diet (2% cholesterol and 6% corn oil) for 8 weeks and then divided into groups of equal average serum cholesterol levels. One group was autopsied, and the others were returned to cholesterol-free diets consisting of commercial laboratory ration or ration augmented with 6% corn oil, peanut oil or PGF, a fat designed to resemble peanut oil minus arachidic and behenic acids. The animals were maintained on the diets for 8 more weeks. On all regimens, severity of atherosclerosis was exacerbated. The extent of exacerbation was significantly less in rabbits fed corn oil than in the others. The extent of exacerbation of lesions appears to be a function of the level of unsaturation of the dietary fats.
Atherosclerosis 1978 Nov
PMID:Cholesterol vehicle in experimental atherosclerosis. Part 16. Effect of peanut oil on pre-established lesions. 71 39

The aortas of 9 months aged Show Racer and White Carneau pigeons were examined for their PGE2, PGF2 alpha and 6-keto-PGF1 alpha synthesis from labelled arachidonic acid by radiothinlayer chromatography. The prostacyclin formation was estimated by means of Moncada's bioassay. PGE2 and PGF 2 alpha synthesis in the aorta of pigeons is higher than in rats, whereas less 6-keto-PGF1 alpha is formed in pigeon aortas. The susceptible White Carneau pigeons synthesitize more prostaglandins than the resistant Show Racer pigeons. PGI2 and 6-keto-PGF 1 alpha-formation is extremely low in avian arota. These data are in part contradicting to our findings im mammalians (where the atherosclerosis susceptible animals generate less PGI2) and warrants sequential measurements of prostaglandin synthesis in aorta to assess its significance during various stages of atherogenesis.
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PMID:Prostaglandin synthesis in aorta of atherosclerosis susceptible and atherosclerosis resistant pigeons. 742 65

F2-isoprostanes are prostaglandin F2-like compounds being formed by non-enzymatic peroxidation of arachidonic acid in vivo. They have a variety of biological actions. The most important compound of this group is 8-epi-PGF(2 alpha) being capable to induce vasconstriction in particular of lung- and renal vascular tissue. Isoprostanes are present in esterified form; in free form they become available after hydrolysis by phospholipase A. An increase in isoprostanes is an important indicator of oxidative stress in-vivo due to a variety of different noxi such as metal- or non-metal ions for cigarette smoke. Isoprostanes show an activation of platelets; as a consequence of the interaction of 8-epi-PGF(2 alpha) with specific receptors platelet aggregation may be induced or may be enhanced together with other agonists. Due to these preliminary results isoprostanes could become an interesting substance in angiology in the future for diagnosis of oxidative stress as well as in the understanding of the pathogenesis of atherosclerosis.
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PMID:[Isoprostanes, a new substance group in angiology--of future significance?]. 922 17

Isoprostanes are members of a complex family of lipids, isomers of the conventional enzymatically derived prostaglandins (PG), which are produced in vivo primarily, if not exclusively, by a free radical-catalyzed peroxidation of polyunsaturated fatty acids. Most of the work has been focused upon a group of isomers of the enzyme-derived PGF(2alpha), called F(2)-isoprostanes (F(2)-iPs). Because of their mechanism of formation, chemical stability and the rapid development of sensitive methods for their measurement, they have the attraction as non-invasive indices of oxidant stress in vivo. Altered generation of F(2)-iPs has been reported in a variety of clinical settings putatively associated with oxidant stress. These include atherosclerosis, chronic obstructive pulmonary disease and Alzheimer's disease. Furthermore, the measurement of specific F(2)-iPs may provide a sensitive biochemical basis for rational dose-selection of natural and synthetic inhibitor of lipid peroxidation. Although F(2)-iPs possess biological activities in vitro and in vivo, much remains to be learned about their role and as mediators of the cellular effects of lipid peroxidation and oxidant stress.
Atherosclerosis 1999 Nov 01
PMID:F(2)-isoprostanes: sensitive and specific non-invasive indices of lipid peroxidation in vivo. 1052 18

This study was conducted to investigate whether the novel orally active nonpeptide angiotensin II (Ang II) AT(1) receptor antagonist irbesartan interacts with the thromboxane A(2)/prostaglandin endoperoxide H(2) (TxA(2)/PGH(2)) receptor in canine coronary arteries and human platelets. Coronary artery rings were isolated from male dog hearts (n = 18) and isometric tension of vascular rings was measured continuously at optimal basal tension in organ chambers. Autoradiographic binding of [(3)H]SQ29,548, a TxA(2) receptor antagonist, in canine coronary sections was determined. Blood for platelet aggregation studies was collected by venous puncture from healthy human volunteers (n = 6) who were free of aspirin-like agents for at least 2 weeks. Vascular reactivity and platelet aggregation in response to the TxA(2) analogs U46619 and autoradioagraphic receptor binding to the TxA(2) receptor antagonist [(3)H]SQ29,548 were studied with and without irbesartan. The TxA(2) analog U46619 produced dose-dependent vasoconstriction in coronary rings (EC(50) = 11.6 +/- 1.5 nM). Pretreatment with irbesartan inhibited U46619-induced vasoconstriction, and the dose-response curve was shifted to the right in a dose-dependent manner. The EC(50) of U46619 was increased 6- and 35-fold in the presence of 1 and 10 microM of irbesartan without a change of maximal contraction. At 1 microM, irbesartan is 2-fold more potent than the AT(1) receptor antagonist losartan in the inhibition of U46619-induced vasoconstriction in canine coronary arteries. In contrast, neither AT(1) receptor antagonists (CV11974 and valsartan), the AT(2) receptor antagonist PD123319, nor the angiotensin converting enzyme inhibitor lisinopril had any effect on U46619-induced coronary vasoconstriction. Irbesartan did not change potassium chloride-induced vasoconstriction; however, irbesartan did inhibit the vasoconstriction mediated by another TxA(2)/PGH(2) receptor agonist prostaglandin F(2alpha) (PGF(2alpha)). Neither the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester nor the cyclooxygenase inhibitor indomethacin had any effect on irbesartan's attenuation of U46619-induced vasoconstriction. Irbesartan specifically reversed U46619-preconstricted coronary artery rings with and without endothelium in a dose-dependent manner. Irbesartan at high concentrations significantly competed for [(3)H]SQ29,548 binding in canine coronary sections. U46619 stimulated dose-dependent human platelet aggregation of platelet-rich plasma. Preincubation with irbesartan significantly inhibited platelet aggregation in a concentration-dependent manner. In conclusion, the dual antagonistic actions of irbesartan by acting at both the AT(1) and TxA(2) receptors in blood vessels and platelets may overall enhance its therapeutic profile in the treatment of hypertension, atherosclerosis, and arterial thrombosis.
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PMID:Novel angiotensin II AT(1) receptor antagonist irbesartan prevents thromboxane A(2)-induced vasoconstriction in canine coronary arteries and human platelet aggregation. 1060 53

Due to the reported associations between a low intake of vitamin E and atherosclerosis on one hand, and between endothelial dysfunction and atherosclerosis on the other hand, we investigated the relationship between endothelium-dependent vasodilation and serum levels of vitamin E (alpha- and gamma-tocopherol) as well as the lipid peroxidation markers malondialdehyde and 8-iso-PGF(2alpha) in a healthy population. Healthy subjects (31 men and 25 women), aged between 20 and 69 years, underwent measurements of forearm blood flow (FBF) at rest and during local infusion of 2 and 4 microg/min of methacholine (Mch, to evaluate endothelium-dependent vasodilation) and 5 and 10 microg/min of sodium nitroprusside (SNP, to evaluate endothelium-independent vasodilation, and during reactive hyperemia using venous occlusion plethysmography. Serum alpha-tocopherol concentration was significantly related to the index of endothelial function (r = 0.46, p < 0.01), defined as the ratio between the maximal dilatations during Mch and SNP infusions. Serum gamma-tocopherol levels were positively related to the maximal FBF during reactive hyperemia (r = 0.54, p < 0.01) in women only. Furthermore, in women only, plasma 8-iso-PGF(2alpha) levels were inversely related to the relative increases in FBF during both Mch and SNP infusions (r = -0.58 and r = -0.59, p < 0.01 for both). The results show a relationship between the levels of alpha-tocopherol and endothelial vasodilatory function, suggesting a beneficial role for this potent lipid-soluble antioxidant also in a population sample of apparently healthy subjects. Furthermore, in women, the accumulation of lipid peroxidation products such as 8-iso-PGF(2alpha) seems to be associated with an impaired vasodilation in general.
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PMID:Relationships between endothelium-dependent vasodilation, serum vitamin E and plasma isoprostane 8-iso-PGF(2alpha) levels in healthy subjects. 1062 24

Atherosclerosis involves a complex array of factors, including leukocyte adhesion and platelet vasoactive factors. Aspirin, which is used to prevent secondary complications of atherosclerosis, inhibits platelet production of thromboxane (Tx) A(2). The actions of TxA(2) as well as of other arachidonic acid products, such as prostaglandin (PG) H(2), PGF(2alpha), hydroxyeicosatetraenoic acids, and isoprostanes, can be effectively antagonized by blocking thromboxane (TP) receptors. The purpose of this study was to determine the role of platelet-derived TxA(2) in atherosclerotic lesion development by comparing the effects of aspirin and the TP receptor antagonist S18886. The effect of 11 weeks of treatment with aspirin (30 mg. kg(-1). d(-1)) or S18886 (5 mg. kg(-1). d(-1)) on aortic root atherosclerotic lesions, serum levels of intercellular adhesion molecule-1 (ICAM-1), and the TxA(2) metabolite TxB(2) was determined in apolipoprotein E-deficient mice at 21 weeks of age. Both treatments did not affect body or heart weight or serum cholesterol levels. Aspirin, to a greater extent than S18886, significantly decreased serum TxB(2) levels, indicating the greater efficacy of aspirin in preventing platelet synthesis of TxA(2). S18886, but not aspirin, significantly decreased aortic root lesions as well as serum ICAM-1 levels. S18886 also prevented the increased expression of ICAM-1 in cultured human endothelial cells stimulated by the TP receptor agonist U46619. These results indicate that inhibition of platelet TxA(2) synthesis with aspirin has no significant effect on atherogenesis or adhesion molecule levels. The effects of S18886 suggest that blockade of TP receptors inhibits atherosclerosis by a mechanism independent of platelet-derived TxA(2), perhaps by preventing the expression of adhesion molecules whose expression is stimulated by eicosanoids other than TxA(2).
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PMID:The thromboxane receptor antagonist S18886 but not aspirin inhibits atherogenesis in apo E-deficient mice: evidence that eicosanoids other than thromboxane contribute to atherosclerosis. 1089 3

Isoprostanes (IP) have been identified as reliable markers of in vivo oxidation injury. Recently, in vascular tissue and blood as well as urine of cigarette smokers, increased IP values have been discovered. We examined 47 adults (26 males, 21 females; aged 30-66 years), admitted to a cardiovascular unit on an outpatient basis, with various risk factors but without any sign of manifestation of atherosclerosis. Refraining from cigarette smoking for a few days resulted in a significant drop of plasma, serum, and urinary 8-epi-PGF(2alpha). Thereafter, a further continuous decrease was monitored, reaching a steady state after about 4 weeks after quitting cigarette smoking. Prevalues of 8-epi-PGF(2alpha) were higher, depending on the type and number of risk factors; the decrease after quitting, however, was comparable. These results indicate that exsmokers may rapidly recover from their enhanced in vivo oxidation.
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PMID:Quitting cigarette smoking results in a fast improvement of in vivo oxidation injury (determined via plasma, serum and urinary isoprostane). 1094 41

Homocysteine is a risk factor for the development of atherosclerosis and its thrombotic complications. We have employed an animal model to explore the hypothesis that an increase in reactive oxygen species and a subsequent loss of nitric oxide bioactivity contribute to endothelial dysfunction in mild hyperhomocysteinemia. We examined endothelial function and in vivo oxidant burden in mice heterozygous for a deletion in the cystathionine beta-synthase (CBS) gene, by studying isolated, precontracted aortic rings and mesenteric arterioles in situ. CBS(-/+) mice demonstrated impaired acetylcholine-induced aortic relaxation and a paradoxical vasoconstriction of mesenteric microvessels in response to superfusion of methacholine and bradykinin. Cyclic GMP accumulation following acetylcholine treatment was also impaired in isolated aortic segments from CBS(-/+) mice, but aortic relaxation and mesenteric arteriolar dilation in response to sodium nitroprusside were similar to wild-type. Plasma levels of 8-epi-PGF(2alpha) (8-IP) were somewhat increased in CBS(-/+) mice, but liver levels of 8-IP and phospholipid hydroperoxides, another marker of oxidative stress, were normal. Aortic tissue from CBS(-/+) mice also demonstrated greater superoxide production and greater immunostaining for 3-nitrotyrosine, particularly on the endothelial surface. Importantly, endothelial dysfunction appears early in CBS(-/+) mice in the absence of structural arterial abnormalities. Hence, mild hyperhomocysteinemia due to reduced CBS expression impairs endothelium-dependent vasodilation, likely due to impaired nitric oxide bioactivity, and increased oxidative stress apparently contributes to inactivating nitric oxide in chronic, mild hyperhomocysteinemia.
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PMID:Endothelial dysfunction in a murine model of mild hyperhomocyst(e)inemia. 1095 23

The cyclooxygenase (COX) product, prostacyclin (PGI(2)), inhibits platelet activation and vascular smooth-muscle cell migration and proliferation. Biochemically selective inhibition of COX-2 reduces PGI(2) biosynthesis substantially in humans. Because deletion of the PGI(2) receptor accelerates atherogenesis in the fat-fed low density lipoprotein receptor knockout mouse, we wished to determine whether selective inhibition of COX-2 would accelerate atherogenesis in this model. To address this hypothesis, we used dosing with nimesulide, which inhibited COX-2 ex vivo, depressed urinary 2,3 dinor 6-keto PGF(1alpha) by approximately 60% but had no effect on thromboxane formation by platelets, which only express COX-1. By contrast, the isoform nonspecific inhibitor, indomethacin, suppressed platelet function and thromboxane formation ex vivo and in vivo, coincident with effects on PGI(2) biosynthesis indistinguishable from nimesulide. Indomethacin reduced the extent of atherosclerosis by 55 +/- 4%, whereas nimesulide failed to increase the rate of atherogenesis. Despite their divergent effects on atherogenesis, both drugs depressed two indices of systemic inflammation, soluble intracellular adhesion molecule-1, and monocyte chemoattractant protein-1 to a similar but incomplete degree. Neither drug altered serum lipids and the marked increase in vascular expression of COX-2 during atherogenesis. Accelerated progression of atherosclerosis is unlikely during chronic intake of specific COX-2 inhibitors. Furthermore, evidence that COX-1-derived prostanoids contribute to atherogenesis suggests that controlled evaluation of the effects of nonsteroidal anti-inflammatory drugs and/or aspirin on plaque progression in humans is timely.
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PMID:Acceleration of atherogenesis by COX-1-dependent prostanoid formation in low density lipoprotein receptor knockout mice. 1124 83


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