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

Coronary mortality among men is higher than in women in all age groups. Women seem to be protected from coronary disease. After the age of 50, coronary mortality increases fast in women and slows down in men, so that the mortality curves tend to join at some level. This fact led to believe that menopause had some influence over the non-proportional increase of coronary risk in women. Estrogens would be responsible for this protection before menopause and their further decrease would be the cause of higher coronary mortality. Mortality rate data, taken from a population with a high rate disease or a low rate disease, do not prove the above statement. For this reason it is said to by a myth. If it were a myth, then to try to prevent by administrating a substitute of these estrogens during menopause would be a paradox. If we accept that coronary atherosclerosis disease has many etiological factors, we should conclude that, besides hormones, there are other elements involved. The kind of personality, the way of life together with genetic factors related to gender would explain differences in frequency and mortality due to coronary heart disease, which, in this case, clearly advocates for women.
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PMID:[Cardiovascular risk in menopause: myth, paradox or reality. The importance of clinical observations vs statistical data interpretation]. 1043 68

Estrogens and immunity against LDL could be important in atherogenesis. Herein, we describe the development of atherosclerotic lesions and cellular immune responses to modified LDL in male and female apoE knockout (E0) mice over time, and the effect of 17beta-estradiol on atherosclerosis-related cellular immunity. Animals were studied after 16 or 48 weeks of normocholesterol diet. Aortic lesions, lymphocyte populations, and the cellular immune response against modified LDL, with or without 17beta-estradiol, were analyzed. Atherosclerotic lesions were larger and more advanced in young female than in male E0 mice. In older mice, no significant difference in lesion size or maturity was discerned between males and females. In spleen cell cultures of young females, addition of 17beta-estradiol induced a proliferative T-cell response to oxidized LDL, while no such effect was seen in males. In similar cultures from old E0 mice, T-cells from female animals were activated by oxidized LDL even in the absence of exogenous estrogens. These data show important sex differences in the development of atherosclerosis. They suggest that these differences may be related to sex differences in the cellular immune responses to the atherosclerosis-related autoantigen, oxidized LDL.
Atherosclerosis 1999 Aug
PMID:Effects of sex and age on atherosclerosis and autoimmunity in apoE-deficient mice. 1048 57

Although estrogen-dependent effects on the vasculature were first observed more than a century ago, many of the mechanisms by which estrogens interact with the vascular wall have been identified only in the past 15 years. Estrogens bind to vascular estrogen receptors (ER), including the ER alpha, the novel ER beta as well as to membrane-bound receptors. Estrogens have direct effects in human coronary and internal mammary arteries by inducing rapid, endothelium-independent relaxation, enhancement of endothelial function and inhibition of vasoconstriction by vasoactive agonists. Furthermore, estrogens contribute to vascular homeostasis through modulation of gene expression, changes in membrane potentials, as well as expression and function of receptors. In addition, estrogens interfere with the activity of vasoactive peptides and vascular enzymes and act as natural antioxidants. Some of these effects have also been observed for phyto-estrogens, which are important dietary components in Asian countries. In the vasculature, the sum of these actions of estrogens results in vasodilatation and inhibition of vascular cell growth. Accordingly, estrogens have been shown to improve vascular function of animals and humans and to inhibit the response to injury after balloon angioplasty and the progression of atherosclerosis. Prospective clinical studies are ongoing to determine whether replacement therapy with estrogen or derivatives provides an alternative to lower cardiovascular mortality in postmenopausal women.
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PMID:Vascular effects of estrogens: rapid actions, novel mechanisms, and potential therapeutic implications. 1067 98

Animal experiments are widely accepted in arteriosclerosis research. The aim of the present study was to establish an organ culture model (rings of rabbit aortic vessels) to investigate inhibitory estrogen effects on post injury neointima formation in the vessel wall and to examine whether these effects are cytotoxic. Estrogens are used for secondary prevention of atherosclerosis in postmenopausal women (estrogen replacement therapy/ERT). Phytoestrogens as well as the ovarian 17 beta-estradiol have been demonstrated to inhibit proliferation and migration of vascular smooth muscle cells which are key events in atherogenesis and restenosis after coronary angioplasty. In situ endothelial denudation of the thoracic and abdominal aorta was performed in female rabbits by a 3F Fogarty catheter. Segments of 5 mm were randomized in groups of n = 12 and held in culture. 17 beta-estradiol, Genistein and Daidzein were applied in concentrations of 20 microM, 30 microM, and 40 microM. Groups without estrogen treatment served as controls. The segments were investigated after 21 days. Afterwards, 3 further groups (n = 12) were held with the lowest concentrations of 17 beta-estradiol or the two phytoestrogens having been evaluated to inhibit the neointima formation significantly. After 21 days of treatment these sections were held in medium only for another 7 days to proof whether these segments were still able to proliferate. A denuded control group was held in medium only over 28 days. Compared to controls, 30 microM 17 beta-estradiol, 20 microM Genistein, and 40 microM Daidzein inhibited neointima formation significantly over 21 days. After another 7 days of cultivation in medium only the amount of neointima formation was comparable to that of non-estrogen-treated controls after 21 days. We therefore suggest that the demonstrated inhibitory effect is not explained by toxicity. In conclusion, by the use of this organ culture model it was possible to demonstrate non-toxic post injury effects of different estrogens in the vasculature. Because 24 aortic segments could be taken from one aortic vessel, the number of animals that would have been necessary for an experiment (8 to 10 per group for statistical reasons) could be markedly reduced. The results are of clinical interest because phytoestrogens and 17 beta-estradiol may offer therapeutic options for patients after coronary angioplasty regarding the process of restenosis. Because phytoestrogens do not affect the reproductive system they can also be used in men.
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PMID:Post-injury ex vivo model to investigate effects and toxicity of pharmacological treatment in rings of rabbit aortic vessels. 1108 61

Transforming growth factor-beta (TGF-beta) plays central roles in embryonic development, organogenesis, and physiologic connective tissue remodeling during wound healing and tissue repair as well as in carcinogenesis. Estrogens have key roles in a variety of biological events, such as the development and maintenance of female reproductive organs and bone and lipid metabolism. Previous studies demonstrated that estrogens suppress TGF-beta-induced gene expression, such as type IV collagen in kidney mesangial cells. However, the molecular mechanisms that mediate this antagonistic effect are unknown. To elucidate the mechanisms of cross-talk between TGF-beta and estrogen receptor (ER) signaling pathways, we reconstituted TGF-beta and ER signaling in human kidney carcinoma cells. Here we demonstrate that TGF-beta-induced activation of Sma and MAD-related protein 3 (Smad3) activity, one of the major intracellular transducers of TGF-beta signaling, was suppressed by ER, whereas ER-mediated transcriptional activation was enhanced by TGF-beta signaling. We provide evidence that this two-way cross-talk between the estrogen and TGF-beta signaling pathways was the result of direct physical interactions between Smad3 and ER. These findings have implications for a variety of disease states, such as the pathophysiology of kidney function, atherosclerosis, and breast cancer.
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PMID:Cross-talk between transforming growth factor-beta and estrogen receptor signaling through Smad3. 1155 47

Clearly, a new era has begun, with increasing numbers of the scientific/medical community asking whether estrogens have any cardiovascular benefits. Doubts have arisen from two randomized prospective trials. The Heart and Estrogen/progestin Replacement Study (women who were generally beyond 65 years of age with preexisting coronary heart disease) found no benefit in reducing coronary events by a combination of estrogens and a progestin. Later, the Estrogen Replacement Atherosclerosis Trial reported that no benefit could be shown for either conjugated equine estrogens only or the combined therapy group for women with preexisting coronary artery stenosis. There are lessons to be taken from monkey models about the new conundrum. Estrogens have beneficial effects in the early stages of atherogenesis, but have little or no beneficial effects in the final stages of plaque complications, instability and coronary heart disease events. Using the monkey model, we have addressed the question of when "primary prevention" should begin. We examined the effect of contraceptive steroid treatment of stressed animals at high risk to progressing atherosclerosis due to their estrogen deficiency and subsequently examined the effect of estrogen replacement therapy or no estrogen replacement therapy following surgical menopause. The most robust inhibition of atherosclerosis progression was found in those animals given contraceptive steroids premenopausally and subsequently estrogen replacement postmenopausally. The notion of starting contraceptive therapy during the perimenopausal period to be followed immediately with estrogen replacement postmenopausally is likely to be the most favorable approach to the inhibition of atherosclerosis progression.
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PMID:The new conundrum: do estrogens have any cardiovascular benefits? 1199 32

Stroke is a leading cause of disability and death in women, despite progress in its prevention and treatment. As with coronary artery disease, the incidence of stroke rises after the menopause, in parallel with metabolic changes that add up to create an unfavourable risk factor profile for cardiovascular disease. The menopause metabolic syndrome, which includes weight gain and changes in lipids, insulin resistance, endothelial dysfunction, increased levels of homocysteine, lipoprotein (a) and several coagulation factors, may in part be attributable to estrogen deficiency, and may be reversible with hormone replacement therapy (HRT). As for blood pressure, a major detrimental risk factor for stroke, it is probably not affected by either the menopause per se or by HRT. Abundant experimental data exist indicating that estrogens have both anti-atherosclerotic and neuroprotective effects. The width or thickness of the carotid wall is a good indicator of carotid atherosclerosis; it increases after the menopause transition, and decreases with HRT. Estrogens may enhance cerebral blood flow and reduce vascular resistance. In animal models of stroke, estrogen induced anti-ischaemic effects. Several large-scale epidemiological studies have verified the concept of primary protection of stroke by HRT, though others have failed to do so. In light of these contradictory data, several recent reports were highly significant (Nurses' Health Study, HERS Study, Cancer Prevention II Trial, WEST Trial). Despite the known neural and vascular benefits of estrogen, it is uncertain whether HRT is associated with stroke protection. At present, prevention of stroke should involve proven risk reduction strategies.
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PMID:Menopause and ischaemic stroke: basic, clinical and epidemiological considerations. The role of hormone replacement. 1209 31

Estrogens have been implicated in both worsening and protecting from cardiovascular disease. The effects of 17beta-estradiol (E2) on the cardiovascular system may be mediated, at least in part, by its modulation of local tissue renin-angiotensin systems (RAS). We assessed two critical components, angiotensin-converting enzyme (ACE) and ANG II type 1 receptor (AT(1)R), in the heart, lung, abdominal aorta, adrenal, kidney, and brain in four groups of female Wistar rats (n = 5-6/group): 1) sham ovariectomized, 2) ovariectomized (OVX) treated with subcutaneous vehicle, 3) OVX treated with 25 mug/day (regular) E2 subcutaneously, and 4) OVX treated with 250 mug/day (high) subcutaneous E2 for 2 or 5 wk. After 2 wk, plasma ACE activity was not altered by OVX, but it was 34-38% lower in OVX + regular E2 and OVX + high E2 rats compared with sham OVX rats, and these decreases were no longer present after 5 wk. After 5 wk, OVX alone increased ACE activity and binding densities, and AT(1)R binding densities by 15-100% in right ventricle, left ventricle (LV), kidney, lung, abdominal aorta, adrenal and several cardiovascular regulatory nuclei in the brain. These effects were, for the most part, prevented by regular E2 replacement and were reversed to decreases by high E2 treatment. This regulation of tissue ACE and AT(1)R is significant as the activity of these tissue RAS contributes to the pathogenesis and/or progression of hypertension, atherosclerosis, and LV remodeling after myocardial infarction.
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PMID:17beta-estradiol downregulates tissue angiotensin-converting enzyme and ANG II type 1 receptor in female rats. 1555 Jun 14

Oxidative stress plays an important role in the pathogenesis of atherosclerosis and can be effectively influenced by radical scavenging enzymes. Estrogens exert antioxidative effects in the vasculature; however, cotreatment with progesterone may abrogate the vasoprotective effects of estrogen. Therefore, the effects of progesterone on the production of reactive oxygen species (ROS) and expression and function of antioxidant and oxidant enzymes were investigated in cultured vascular smooth muscle cells (VSMCs) and vascular tissue of mice. Progesterone time- and concentration-dependently downregulated extracellular superoxide dismutase (ecSOD) and manganese superoxide dismutase (MnSOD) expression and enzyme activity and reversed 17beta-estradiol-induced overexpression of ecSOD and MnSOD in VSMCs. Nuclear run-on assays revealed that progesterone decreases MnSOD and ecSOD transcription rates. Consequently, progesterone increased ROS release in VSMCs that was prevented by concomitant treatment with 17beta-estradiol. Estrogen deficiency in ovariectomized mice was associated with an increase in vascular superoxide release and NADPH oxidase activity. Estrogen replacement prevented this increase, whereas progesterone substitution enhanced ROS production and NADPH oxidase activity. The modulation of superoxide release coincided with decreased expression of ecSOD and MnSOD and upregulation of the p22phox and p67phox subunits of the NADPH oxidase complex in progesterone-treated animals. Furthermore, administration of progesterone to ovariectomized mice treated with 17beta-estradiol abrogated the antioxidative effects of estrogen. Progesterone antagonizes the vasoprotective effects of estrogen on ecSOD and MnSOD expression and increases NADPH oxidase activity. These findings may in part explain why hormone replacement therapy with estrogen plus progesterone displayed no beneficial effect on cardiovascular event rates in the prospective clinical trials.
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PMID:Progesterone antagonizes the vasoprotective effect of estrogen on antioxidant enzyme expression and function. 1619 79

Estrogens confer atheroprotective effects that remain poorly understood. We hypothesised that estrogens directly target monocytes, and investigated the pathways via which estrogens might impact on monocyte adhesion. In an in vitro model of the vasculature (parallel plate laminar flow chamber, 2 dynes/cm2), 17beta-estradiol (24 h, 0.1-1 microM) potently inhibits monocyte adhesion. In parallel, 17beta-estradiol down-regulates Rac1 GTPase activity in monocytes. Transfection of monocytic cells with dominant-negative Rac1N17 significantly decreases adhesion to human endothelial cells, while constitutively-active Rac1L61 augments adhesion. As determined by pull-down assays, Rac1 is rapidly activated by the chemokine stromal-derived factor-1 (SDF-1) in human monocytes (100 nM, 30 s). Within the same time period, SDF-1 mediates both ICAM-1/beta2- and VCAM-1/beta1-integrin-dependent monocyte adhesion, which is significantly decreased in cells overexpressing dominant-negative Rac1N17. Inhibitor studies revealed that Rac1-triggered monocyte adhesion is dependent upon actin rearrangement, while production of reactive oxygen species via Rac1 is not involved. Estrogen directly inhibits monocyte adhesion via down-regulation of Rac1, which is both necessary and sufficient to enhance monocyte adhesion under physiological flow conditions. These studies extend current knowledge about the mechanisms responsible for the vascular recruitment of pro-inflammatory cells, and potentially open up new avenues for the therapy of atherosclerosis.
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PMID:17Beta-estradiol inhibits monocyte adhesion via down-regulation of Rac1 GTPase. 1633 75


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