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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The different diseases associated with the insulin resistance syndrome--diabetes mellitus or impaired carbohydrate tolerance, atherogenic lipoprotein phenotype, arterial hypertension and central type of obesity are the main risk factors of atherosclerosis. The reduced sensitivity of target tissues to the metabolic action of insulin (insulin resistance) is considered at present a separate risk factor. The authors analyze on the basis of a group of 210 coronarographic patients the influence of insulin resistance and associated etiopathogenetic risk factors on coronary lesions evaluated by the method of quantitative coronarography. From the results of the investigation ensues that insulin resistance is the most frequent metabolic deviation in patients with coronary disease whereby in the macrovascular group it was found in 74.3% and in the group with microvascular angina pectoris in 64.3% of the patients. Changes in the lipoprotein spectrum were a more frequent and earlier manifestation of insulin resistance than impaired carbohydrate metabolism. The change from functional changes of the vascular wall (impaired endothelium-dependent vasodilatation) to the development of an atheromatous plaque depends on the total number of cholesterol conveying lipoproteins assessed by means of the apoprotein B level and on the capacity of the reverse cholesterol transport, whereby both mechanisms are greatly influenced by insulin sensitivity. The degree of coronary affection evaluated by means of a coronary score, is in patients with manifest diabetes comparable with the affection in patients with insulin resistance without manifest diabetes and these two groups differ very significantly as to the extent and degree of affection from patients with a normal sensitivity to the effect of insulin.
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PMID:[Insulin resistance and the coronary syndrome]. 1042 19

Recent developments in molecular biological techniques allowed us to examine the genetic risk factors responsible for essential hypertension. The candidate gene approach revealed that several gene polymorphisms increase the relative risk for hypertension. Most genetic studies, however, examined only young subjects but not elderly ones. To examine the importance of gene polymorphisms in elderly hypertension, we carried out a case-control study and compared the odds ratio for hypertension between young (< 60) and elderly (> or = 60) subjects. The participants of this study were recruited from the outpatients of Osaka University Medical School with informed consent. We examined the following polymorphisms as candidates: the angiotensinogen (AGT/M235T), angiotensin converting enzyme (ACE I/D), angiotensin II type 1 (AT1/A1166C) and type 2 (AT2/C3123A) receptors, alpha-adducin (adducin/Gly460Trp), methylenetetrahydrofolate reductase (MTHHR/C677T), and apolipoprotein (apoE/epsilon 4, apoE/T-491A). In young subjects, the AGT/T235 allele significantly increased the odds ratio for hypertension but not in elderly subjects. In young males, the AT2/A3123 allele was also associated with hypertension but not in females or in elderly subjects. Other associations between polymorphism and hypertension did not reach a significant level. To sum up, it was revealed that some polymorphisms increase the susceptibility for hypertension but others do not, which suggests that there is heterogeneity in the genetic involvement of polymorphism due to aging.
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PMID:[Genetic analysis of candidate gene polymorphisms in elderly hypertension]. 1055 62

The number and composition of apoprotein B (apoB)-containing lipoproteins that are very low density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and low-density lipoprotein (LDL) have been analyzed in subjects with essential hypertension who have no obesity and glucose intolerance. Twenty-three essential hypertensive subjects without diabetes mellitus and obesity were recruited. VLDL, IDL, LDL, and high-density lipoprotein (HDL) were separated by ultracentrifugation in the 23 hypertensive and 17 healthy subjects (control group). ApoB was determined by highly sensitive latex agglutination method in each lipoprotein fraction. There were no significant differences in age and body mass index between the hypertension and control groups. In hypertension, cholesterol levels significantly increased in plasma (13%, P < .05) and in LDL (20%, P < .05), but decreased in HDL (-14%, P < .05). Triglyceride significantly increased in plasma (66%, P < .05) and in VLDL (105%, P < .05). ApoB also significantly increased in plasma and all lipoprotein fractions except HDL. (plasma, 35%; VLDL, 94%; IDL, 82%; LDL, 42%; P < .05). With respect to lipoprotein composition, the ratio of cholesterol to apoB significantly decreased in IDL (P < .05) and LDL (P < .05). In essential hypertension, the number of apoB-containing lipoproteins (VLDL, IDL, LDL) all increased. A low ratio of cholesterol to apoB without changes in the ratio of triglyceride to apoB was noted in IDL and LDL, indicating the presence of small dense lipoprotein particles. Characteristic disorders of pure essential hypertension are characterized by hyperapobetalipoproteinemia and small dense LDL.
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PMID:Hyperapobetalipoproteinemia with compositional abnormality of LDL and IDL, a characteristic lipoprotein alteration in essential hypertension. 1091 44

While a complete understanding of the pathogenesis of Alzheimer's disease (AD) remains elusive, many conclusions can be drawn from the numerous epidemiological studies undertaken to date. Prevalence and incidence estimates show consistency, following a roughly exponential pattern with a doubling of both parameters roughly every five years after age 65. Roughly 7% of the population aged 65 and over has AD. The clinical course of the disease is reasonably well established and mortality rates rise with increasing levels of cognitive deficit. Four risk factors for AD are firmly established: increasing age, the presence of the apolipoproteinE-epsilon4 allele, familial aggregation of cases, and Down's syndrome. Numerous other associations have been shown in some studies, but not in others. For example, women generally appear at higher risk than men, as do people with lower levels of education; depression is probably prodromal; head injury is an established risk factor, and may interact with the apoE gene; several occupational exposures appear hazardous, and exposure to aluminum in the water supply confers excess risk. Hypertension and other vascular symptoms appear to predispose to AD, which is now seen as nosologically closer to vascular dementia than was previously believed. Several apparently protective factors have been identified, although preventive trials based on these have so far shown minimal effectiveness. The use of non-steroidal anti-inflammatory drugs to treat arthritis is associated with a reduced risk of AD, as is estrogen use by post-menopausal women. Physical activity appears beneficial, as does a diet with high levels of vitamins B6, B12 and folate. while red wine in moderate quantities appears protective. This review concludes with a discussion of the strengths and limitations of current epidemiological methods for studying Alzheimer's disease.
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PMID:Alzheimer's disease: insights from epidemiology. 1144 98

The vasculoprotective effects of sex hormones, particularly estrogens, have been attributed to their ability to increase the bioavailability of nitric oxide through activation of endothelial nitric oxide synthase (eNOS). To dissect the relative contribution in vivo of eNOS, sex hormones, and their interaction in two complex vascular phenotypes, hypertension and atherosclerosis, we used mice doubly deficient in eNOS and apoE (nnee) or lacking only apoE (NNee). Females and males were gonadectomized at 1 month of age and implanted either with control pellets or pellets releasing 17beta-estradiol (E2). Hormonally intact nnee mice have elevated blood pressure (BP) and increased atherosclerosis compared with NNee mice, but on removal of gonads, BP and atherosclerosis decreased significantly in nnee mice but not in NNee mice. Three months of treatment with exogenous E2 dramatically reduced atherosclerosis and significantly lowered BP in both NNee and nnee mice compared with animals treated with control pellets. Thus exogenous E2 has strong BP-lowering and atheroprotective effects in apoE-deficient mice, but eNOS is not essential for either effect. Endogenous sex hormones, on the other hand, cause significant damage to the vasculature in the absence of eNOS, but these effects are overridden by interactions between eNOS and sex hormones.
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PMID:Interactions between endothelial nitric oxide synthase and sex hormones in vascular protection in mice. 1185 27

The Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study was organized to document the natural history of athersclerosis and to determine the relation of cardiovascular risk factors to atherosclerosis in young subjects. Pathology laboratories in 15 centers collected coronary arteries, aortas, and other tissues from over 3,000 subjects age 15 to 34 who died of external causes between 1987 and 1994. The extent, prevalence, and topography of arterial lesions were evaluated and risk factors were analyzed in a central laboratory. Postmortem risk factors included serum lipoproteins, serum thiocyanate (smoking), glycohemoglobin (diabetes), thickness of panniculus adiposus and body mass index (obesity), changes in small renal arteries (hypertension), and apoprotein isoforms. The PDAY study confirmed the origin of atherosclerosis in childhood, showed that progression toward clinically significant lesions may occur in young adulthood and demonstrated that the progression of atherosclerosis is strongly influenced by coronary heart disease (CHD) risk factors. Recent PDAY studies have shown that a significant number of advanced coronary artery lesions have microscopic qualities associated with susceptibility to rupture and that CHD risk factors are associated with the development of these characteristic microscopic qualities. The PDAY archive continues to provide an important resource for new investigators throughout the world that contribute to the understanding of atherosclerosis, the underlying cause of most cardiovascular disease and the leading cause of debilitating illness and death in this country. The PDAY findings emphasize the need to modify risk factors in young people to retard the development of atherosclerotic lesions, particularly clinically significant lesions. Thus, true primary prevention of atherosclerosis must being in childhood or early adolescence.
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PMID:Natural history and risk factors of atherosclerosis in children and youth: the PDAY study. 1194 37

Numerous studies have implicated either the presence or absence of CD36 in the development of hypertension. In addition, hypercholesterolemia is associated with the loss of nitric oxide-induced vasodilation and the subsequent increase in blood pressure. In the current study, we tested the hypothesis that diet-induced hypercholesterolemia promotes the disruption of agonist-stimulated nitric oxide generation and vasodilation in a CD36-dependent manner. To test this, C57BL/6, apoE null, CD36 null, and apoE/CD36 null mice were maintained on chow or high fat diets. In contrast to apoE null mice fed a chow diet, apoE null mice fed a high fat diet did not respond to acetylcholine with a decrease in blood pressure. Caveolae isolated from in vivo vessels did not contain endothelial nitric-oxide synthase and were depleted of cholesterol. Age-matched apoE/CD36 null mice fed a chow or high fat diet responded to acetylcholine with a decrease in blood pressure. The mechanism underlying the vascular dysfunction was reversible because vessels isolated from apoE null high fat-fed mice regained responsiveness to acetylcholine when incubated with plasma obtained from chow-fed mice. Further analysis demonstrated that the plasma low density lipoprotein fraction was responsible for depleting caveolae of cholesterol, removing endothelial nitric-oxide synthase from caveolae, and preventing nitric oxide production. In addition, the pharmacological removal of caveola cholesterol with cyclodextrin mimicked the effects caused by the low density lipoprotein fraction. We conclude that the ablation of CD36 prevented the negative impact of hypercholesterolemia on agonist-stimulated nitric oxide-mediated vasodilation in apoE null mice. These studies provide a direct link between CD36 and the early events that underlie hypercholesterolemia-mediated hypertension and mechanistic linkages between CD36 function, nitric-oxide synthase activation, caveolae integrity, and blood pressure regulation.
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PMID:Hypercholesterolemia promotes a CD36-dependent and endothelial nitric-oxide synthase-mediated vascular dysfunction. 2773 24

Increased production of reactive oxygen and nitrogen species has recently been implicated in the pathogenesis of endothelial dysfunction associated with atherosclerosis, hypertension and aging. Oxidant induced cell injury triggers the activation of nuclear enzyme poly(ADP-ribose) polymerase (PARP), which in turn contributes to cardiac and vascular dysfunction in various pathophysiological conditions including diabetes, reperfusion injury and circulatory shock. Here we investigated the role of PARP activation in the pathogenesis of cardiac and endothelial dysfunction associated with atherosclerosis, hypertension and aging. Retired breeder spontaneously hypertensive rats (SHR, 40 weeks old) and apolipoprotein E knockout mice (apoE-Ko, 10 weeks old) were treated for 20 weeks with vehicle or the potent PARP inhibitor PJ34. In the vehicle-treated SHR rats and apoE-Ko mice (kept on atherogenic diet) there was a significant loss of endothelial function, as measured by the relaxant responsiveness of vascular rings to acetylcholine. SHR rats also developed severe hypertension and cardiac hypertrophy. Treatment with the PARP inhibitor did not influence high blood pressure and cardiac hypertrophy in SHR rats, but it improved Ach-induced, NO-mediated vascular relaxation. In addition to the beneficial effects of chronic treatment with PARP inhibitor, 1-h in vitro incubation of aortic rings from SHR rats with PJ34 (3 micromol/l) was also able to improve the endothelial dysfunction. In contrast, in apoE-Ko mice PJ34 treatment did not affect the parameters studied. Thus, PARP activation contributes to the pathogenesis of endothelial dysfunction associated with hypertension and aging, but not in the current experimental model of atherosclerosis.
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PMID:Activation of poly(ADP-ribose) polymerase contributes to the endothelial dysfunction associated with hypertension and aging. 1201 85

Combined oral contraceptives (OCs) have nearly total efficacy when correctly used and good overall tolerance among most women under 40, but there are several significant contraindications to their use. Women with hypertension, hyperlipidemia, diabetes, minor mastopathy, or premenstrual tension should not use OCs containing estrogen. Macroprogestational OCs administered generally 20 days out of 28 are useful when an antiestrogen effect is sought or when metabolic anomalies are to be avoided. An antiestrogen effect may be desired for women over 40 suffering from relative or absolute hyperestrogenism, or for women with premenstrual syndrome, menorrhagia related to endometrial hyperplasia or other menstrual problems, or benign mastopathies. An antiestrogen effect may also be desired to prevent cellular pathologies common after age 40. Some anomalies of metabolism, blood pressure, and coagulation persist in users of combined OCs regardless of the dose or the compounds used in the formulation. Progestins derived from testosterone were the first to be used in contraception and provide good cycle control and antigonadotropic activity, along with a powerful antiestrogen effect. But they may have metabolic side effects and cause signs of hyperandrogenism. Progestins derived from progesterone have been studied in health women and in those with different risk factors. Chlormadinone acetate has been used in women at high vascular risk, and promegestone has been used in women with fibrocystic breast disorders. A study was also done on 36 healthy women for 6 months using nomegestrol acetate. The preliminary results were good but the numbers of women were small, they had no metabolic risk factors, and the treatment periods were short. The results thus cannot be extrapolated to subjects at risk or for use during longer periods. The only observed modifications (essentially declines in apoprotein A1 and elevation of antithrombine) were probably attributable to the decline in average estradiol levels and without significance for risk. A disadvantage of these methods is that they have not been authorized for marketing as contraceptives in France and no Pearl index is available. Although the incidence of menstrual problems is not well known, such problems appear to be relatively frequent. The hypoestrogenism often sought for women with gynecological pathologies is not necessarily desirable for women using these methods because of metabolic problems or age over 40. A sufficient estradiol level protects against premature bone loss and has important metabolic effects including better production HDL cholesterol. 18 women who experienced menstrual problems with macroprogestational contraceptives were given 5 mg/day of nomegestrol acetate in combination with transdermally administered estradiol. Clinical and metabolic tolerance were excellent, and no pregnancies occurred. Further study is warranted.
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PMID:[Macroprogestative contraception: advantages]. 1231 9

Benefits of high-dose progestational contraception (pregnanes [chlormadinone acetate] or norpregnanes, promegestone, nomegestrol acetate) are its anti-estrogenic effect and its overall absence of metabolic effects. It lowers apoprotein A1 and increases antithrombin 3, but these changes produce no adverse effects. High-dose progestational contraception is ideal for women with certain contraindications to combined oral contraceptive use: high blood pressure, hyperlipemia, diabetes mellitus, benign breast disease, and premenstrual tension. It inhibits ovulation. Nomegestrol acetate also changes the cervical mucus, making it inhospitable to sperm. The primary side effect of high-dose progestational contraception is menstrual cycle disturbances. A study of 5 mg nomegestrol acetate among women aged 19-40 used for 20 days of each 28 day cycle revealed no pregnancies. A preliminary study shows that transdermal administration of nomegestrol acetate and estradiol 17 beta adequately treats hypoestrogeny. In conclusion, high-dose progestational contraception produces excellent metabolic results and reduces clinical manifestations of hyperestrogeny.
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PMID:[High-dose progestational contraception: advantages]. 1231 10


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