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

Effects of thyroidectomy (TX; 10 wk) on the performance of perfused hearts from spontaneously hypertensive rats (SHR) were compared with effects on hearts from normotensive Wistar-Kyoto (WKY) controls. TX prevented the development of hypertension in SHR and moderately reduced arterial pressure of WKY, confirming previous observations. TX also reduced heart-to-body-weight ratio (relative left ventricular hypertrophy) but not left-to-right ventricular weight ratio (absolute hypertrophy) of SHR. The performances of euthyroid SHR and WKY hearts were similar to each other. TX reduced maximum left ventricular pulse pressure to the same extent in both strains and had no effect on hydraulic work, O2 consumption, or efficiency of contraction in either strain. However, TX reduced maximum left ventricular +dP/dt of SHR but not of WKY hearts. The results show that hypothyroidism selectively depresses the contractility (LV +dP/dt) of SHR hearts but otherwise has similar effects on the performance of hypertensive and normotensive rat hearts.
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PMID:Antihypertensive effect of thyroidectomy in SHR: associated changes in heart performance. 293 86

A monoclonal antibody specific for cardiac troponin T has been used to investigate troponin changes during development in the rat heart. Specificity of the antibody was determined by immunoblot analysis with purified bovine cardiac troponin. In the rat heart, immunoblot analysis shows that anticardiac troponin T reacts with a 42.5-kDa band in fetal ventricles and with a 41-kDa band in adult ventricles. The faster migrating troponin T is present in traces in the fetal heart and increases markedly during the first 2 weeks after birth, concomitantly with the progressive decrease of the slower migrating form that is no longer detectable in the adult. The pattern of reactivity of the monoclonal antibody is not modified by alkaline phosphatase pretreatment, suggesting that the antibody is not specific for a phosphorylated epitope. Conditions known to affect cardiac myosin composition, such as hypothyroidism and hypertrophy secondary to systemic hypertension, do not change the troponin T isoform profile of adult rat ventricles. The expression and accumulation of the adult isoforms of troponin T are not suppressed by propylthiouracil treatment of pregnant and nursing rats.
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PMID:Troponin T switching in the developing rat heart. 297 62

A study of 21 patients with hypothyroidism, 22 patients with thyrotoxicosis and 18 normal subjects, using echocardiography and bicycle ergometry, demonstrated different mechanisms of reduced working capacity, associated with those conditions. The decrease in chronotropic and inotropic heart reserve, associated with hypothyroidism, is shown to be rooted in slowed-down relaxation of left ventricular posterior wall in the presence of diastolic arterial hypertension, while limited working capacity, associated with thyrotoxicosis, is rooted in resting myocardial hyperfunction due to hyperkinetic circulation.
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PMID:[Hemodynamic mechanisms of the decrease in physical work capacity in hypothyroidism and thyrotoxicosis]. 319 57

Hypothyroidism has been known to be associated, at times, with diastolic hypertension. We have found in 40 thyrotoxic patients that the induction of hypothyroidism by radioiodine therapy significantly increased diastolic blood pressure, raising it above 90 mm Hg in 16 (40%) of the patients. Restoration of euthyroidism with thyroxine administration significantly reduced the systolic and diastolic blood pressures in these patients, with a fall in diastolic pressure below 90 mm Hg in nine of 16 patients. The prevalence of hypothyroidism was determined by measurements of serum thyroxine and thyrotropin concentrations in 688 consecutive hypertensive patients, referred for evaluation and therapy of their hypertension. Hypothyroidism was found in 25 (3.6%) of the patients. Restoration of normal serum thyroxine and thyrotropin levels with thyroid hormone replacement therapy lowered diastolic blood pressure to levels below 90 mm Hg in 32% of these patients who could be followed up after withdrawal of all antihypertensive drug therapy when euthyroidism had been restored (i.e., 1.2% of the 688 patients). It is concluded that diastolic hypertension resulting from hypothyroidism is a relatively common disorder, present in 1.2% of our referred hypertensive patients, that should be sought and treated.
Hypertension 1988 Jan
PMID:Effects of thyroid function on blood pressure. Recognition of hypothyroid hypertension. 333 42

Pyridoxal phosphate is the coenzyme of various decarboxylases involved in the formation of monoamine neurotransmitters such as gamma-aminobutyric acid, serotonin, dopamine, and norepinephrine. Adult male Sprague-Dawley rats placed on a pyridoxine-deficient diet for 8 weeks showed significant hypertension compared with pyridoxine-supplemented controls. Hypothalamic contents of pyridoxal phosphate, gamma-aminobutyric acid, and serotonin in the pyridoxine-deficient rats were significantly lower than those in pyridoxine-supplemented controls. Hypertension was associated with sympathetic stimulation. Treatment of pyridoxine-deficient rats with a single dose of pyridoxine (10 mg/kg body weight) reversed the blood pressure to normal levels within 24 hours, with concomitant restorations of hypothalamic serotonin and gamma-aminobutyric acid as well as the return of plasma norepinephrine and epinephrine to normal levels. Also, pyridoxine treatment reversed the hypothalamic hypothyroidism observed in pyridoxine-deficient rats. These results indicate an association between pyridoxine deficiency and sympathetic stimulation leading to hypertension.
Hypertension 1988 Apr
PMID:Sympathetic stimulation and hypertension in the pyridoxine-deficient adult rat. 335 57

The control of coronary heart disease (CHD) depends primarily on its prevention at an early stage. It is generally agreed that this depends upon the elimination or treatment of the known risk factors for CHD. Among these, hyperlipidaemia occupies a central position. The diagnosis and treatment of this condition is the subject of this statement. Before initiating therapy for primary hyperlipidaemia the common causes of secondary hyperlipidaemia are sought and dealt with, including diabetes, hypothyroidism, over-use of alcohol, renal and liver diseases and certain drugs. Next, an assessment of all risk factors for CHD is carried out, i.e. family history of CHD, smoking, hypertension, high density lipoprotein (HDL) cholesterol measurement, diabetes mellitus and overweight. More intensive therapy is called for in patients with multiple risk factors than in those with lone hyperlipidaemia, and also after successful bypass operation or after coronary angioplasty. Evaluation of hyperlipidaemia in the patient's family is often appropriate. The diagnosis and follow-up of the hyperlipidaemic patient depend on reliable and well-controlled laboratory support. The primary hyperlipidaemias include several distinct diseases that are characterized by elevated serum levels of cholesterol and/or triglyceride with or without abnormally low levels of HDL cholesterol. From these measurements, low-density lipoprotein (LDL) cholesterol levels are calculated [except when triglyceride levels are greater than 500 mg dl-1 (5.6 mmol l-1)]. Elevated LDL levels are causally important in atherosclerosis, and occur in three disorders: familial hypercholesterolaemia, familial combined hyperlipidaemia and common hypercholesterolaemia. The finding of elevated serum triglyceride without marked hypercholesterolaemia may occur in familial hypertriglyceridaemia and sometimes in familial combined hyperlipidaemia. Elevation of serum cholesterol and triglyceride can have several genetic bases, including remnant (type III) hyperlipidaemia and familial combined hyperlipidaemia. The characteristic feature of remnant (type III) hyperlipidaemia (demonstrated by ultracentrifugation in a specialized laboratory) is the presence of cholesterol and triglyceride-rich very low density lipoproteins (VLDL), whereas combined (mixed) hyperlipidaemia is diagnosed when both VLDL (of normal composition) and LDL levels are elevated. Investigation of other family members is necessary to make the diagnosis of familial combined hyperlipidaemia. It depends on the identification of different lipoprotein profiles in affected members of the same family.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The recognition and management of hyperlipidaemia in adults: A policy statement of the European Atherosclerosis Society. 340 74

The present documentation of 23 female patients with pseudotumour cerebri seen in Benghazi, North-Eastern Libya, over a period of 2 years constituted 21 cases with idiopathic pseudotumour and 2 patients with associated endocrine diseases. The clinical, laboratory and CT scan findings indicated idiopathic hypoparathyroidism in 1 case. The association of pseudotumour and hypothyroidism in a 40-year-old woman is suggested to be more than coincidental. The patient group was significantly more obese. Moderate to severe visual loss occurred in 9 patients. The incidence and extent of visual impairment did not correlate with the duration of symptoms, degree of obesity, use of contraceptive pills, steroid treatment, the presence of systemic hypertension, menstrual irregularity or empty sella. The incidence of 1.7 per 100,000 for the total and 3.6 per 100,000 for the female population in Benghazi observed in the present study is believed to be more than the frequency (as assessed by the hospital incidence) reported from other regions. A high prevalence of obesity may partly explain the increased occurrence of pseudotumour cerebri in North-Eastern Libya.
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PMID:Pseudotumour cerebri: incidence and pattern in North-Eastern Libya. 394 85

Careful evaluation was carried out in 93 men older than 50 with erectile dysfunction. Their mean age was 61 years and the disorder had been present for a mean of 4.5 years. While 14 men (15%) had psychosocial factors that may have been pertinent, only 2 scored poorly on an Affect Balance Scale and 3 were receiving psychoactive medications. Results of nocturnal penile tumescence were abnormal in 91%. In 39% penile-brachial pressure indices were suggestive of pelvic vascular disease and in 9% were consistent with a pelvic "steal syndrome." Pelvic or peripheral nerve conduction disorders were also commonly seen in 54%. Endocrinopathy may have contributed to the dysfunction in 35%. Twenty-one men had diabetes mellitus, two new cases of hypothyroidism were discovered and hypogonadism was diagnosed definitely in four and considered likely in five others. Coexisting medical conditions were found in more than 90% of the men, especially hypertension, use of antihypertensive medications and atherosclerotic disease. Previous prostatectomies (19%) and vasectomies (30%) were common in the surgical histories. Given the wide range of disorders uncovered in older men complaining of impotence, diagnostic study of potential causes may lead to a more rational approach for the evaluation and management of these men.
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PMID:Evaluation of impotence in older men. 401 64

To investigate the regulation of arterial pressure and vasoactive hormones in hypothyroidism associated with hypertension, we measured intra-arterial pressure and hourly venous hormones (renin, angiotensin II, aldosterone, catecholamines and cortisol) for 24 hours in five hypertensive patients with primary hypothyroidism before commencing treatment, and again after three to six months of thyroxine replacement therapy. Arterial pressure fell significantly after thyroxine replacement in four patients. Thyroxine treatment was associated with a fall in plasma norepinephrine levels together with a decline in slopes of norepinephrine/arterial pressure regression lines which suggests that the sympathetic system may contribute to the hypertension in hypothyroidism. Variability of heart rate, blood pressure and plasma norepinephrine fell with thyroxine replacement consistent with impaired damping of swings in sympathetic activity in the untreated state. Reciprocal changes in arterial pressure and renin-angiotensin-aldosterone system activity suggested that this system was not the mediator of hypertension in hypothyroidism.
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PMID:Hypertension in hypothyroidism: arterial pressure and hormone relationships. 408 35

Pressure-overload cardiac hypertrophy and hypothyroidism were shown to be associated with a decreased maximum shortening velocity of the myocardium. To investigate the nature of these intrinsic myocardial changes, we studied the energetic consequences in left ventricular papillary muscles of the rat by using standard HILL planar vacuum-deposited antimony-bismuth thermopiles. To evaluate the economy of isometric force generation and maintenance, we analyzed the ratio of liberated heat and developed tension or developed tension-time integral in twitches and experimentally induced tetanic contractions. Hypothyroidism was induced by treatment with propylthiouracil (PTU), and hypertension by operative narrowing of the left renal artery of rats according to Goldblatt (GOP). In the myocardium of hypothyroid as well as hypertensive rats, initial heat per peak twitch tension and total activity-related heat per tension-time integral were significantly reduced compared to controls. In tetanic contractions, total activity-related heat per tension-time integral was also decreased in PTU and GOP myocardium when compared to controls. Thus, the economy of force generation and maintenance is improved in the myocardium of the experimental animals. The data is interpreted in terms of altered cross-bridge cycling rates which are shown to be associated with changes in the myosin isoenzyme pattern. The intrinsic changes of the myocardium due to pressure-overload hypertrophy and hypothyroidism are considered to be adaptive rather than pathologic reactions of the myocardium.
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PMID:Energetic changes of myocardium as an adaptation to chronic hemodynamic overload and thyroid gland activity. 409 75


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