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

The stress system coordinates the adaptive responses of the organism to stressors of any kind.(1). The main components of the stress system are the corticotropin-releasing hormone (CRH) and locus ceruleus-norepinephrine (LC/NE)-autonomic systems and their peripheral effectors, the pituitary-adrenal axis, and the limbs of the autonomic system. Activation of the stress system leads to behavioral and peripheral changes that improve the ability of the organism to adjust homeostasis and increase its chances for survival. The CRH and LC/NE systems stimulate arousal and attention, as well as the mesocorticolimbic dopaminergic system, which is involved in anticipatory and reward phenomena, and the hypothalamic beta-endorphin system, which suppresses pain sensation and, hence, increases analgesia. CRH inhibits appetite and activates thermogenesis via the catecholaminergic system. Also, reciprocal interactions exist between the amygdala and the hippocampus and the stress system, which stimulates these elements and is regulated by them. CRH plays an important role in inhibiting GnRH secretion during stress, while, via somatostatin, it also inhibits GH, TRH and TSH secretion, suppressing, thus, the reproductive, growth and thyroid functions. Interestingly, all three of these functions receive and depend on positive catecholaminergic input. The end-hormones of the hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoids, on the other hand, have multiple roles. They simultaneously inhibit the CRH, LC/NE and beta-endorphin systems and stimulate the mesocorticolimbic dopaminergic system and the CRH peptidergic central nucleus of the amygdala. In addition, they directly inhibit pituitary gonadotropin, GH and TSH secretion, render the target tissues of sex steroids and growth factors resistant to these substances and suppress the 5' deiodinase, which converts the relatively inactive tetraiodothyronine (T(4)) to triiodothyronine (T(3)), contributing further to the suppression of reproductive, growth and thyroid functions. They also have direct as well as insulin-mediated effects on adipose tissue, ultimately promoting visceral adiposity, insulin resistance, dyslipidemia and hypertension (metabolic syndrome X) and direct effects on the bone, causing "low turnover" osteoporosis. Central CRH, via glucocorticoids and catecholamines, inhibits the inflammatory reaction, while directly secreted by peripheral nerves CRH stimulates local inflammation (immune CRH). CRH antagonists may be useful in human pathologic states, such as melancholic depression and chronic anxiety, associated with chronic hyperactivity of the stress system, along with predictable behavioral, neuroendocrine, metabolic and immune changes, based on the interrelations outlined above. Conversely, potentiators of CRH secretion/action may be useful to treat atypical depression, postpartum depression and the fibromyalgia/chronic fatigue syndromes, all characterized by low HPA axis and LC/NE activity, fatigue, depressive symptomatology, hyperalgesia and increased immune/inflammatory responses to stimuli.
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PMID:Hypothalamic-pituitary-adrenal axis, neuroendocrine factors and stress. 1237 95

Thyrotropin (TSH)-secreting pituitary adenoma presenting with hypokalemic periodic paralysis is extraordinarily rare and may be misdiagnosed. We describe a 44-year-old man who suffered from acute muscle weakness and inability to ambulate upon awakening in the morning. Physical examination showed hypertension, tachycardia, and symmetrical flaccid paralysis of all extremities. The major biochemical abnormality was hypokalemia (K+, 2.0 mmol/L) with low urine K+ excretion. A thyroid function study revealed elevated thyroid hormone levels and inappropriately high TSH concentrations (2.10 microU/mL). Brain magnetic resonance imaging delineated a pituitary tumor with suprasellar extension. After trans-sphenoidal removal of tumor, he became clinically and biochemically euthyroid without any further attack of paralysis. Pathological findings confirmed a TSH-secreting adenoma with exclusive TSH immunostaining. TSH-secreting pituitary adenoma must be kept in the differential diagnosis in any thyrotoxic periodic paralysis patients with detectable TSH levels to avoid delaying diagnosis and management.
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PMID:Thyrotropin-secreting pituitary adenoma presenting as hypokalemic periodic paralysis. 1254 87

We managed two patients with secondary hyperthyroidism due to TSH secretion from pituitary adenomas using total intravenous anesthesia with propofol and fentanyl. Both propofol and fentanyl were infused with target-controlled infusion (TCI) systems. The anesthesiologists controlled the target concentration of propofol to maintain the bispectral index (BIS) in a range from 40 to 60, and the target concentration of fentanyl was kept within a range of 2.0 to 3.0 ng.ml-1. Propranolol was injected in 0.4 mg increments to a total dosage of 2.4 to 3.2 mg. Prostaglandin E1 (PGE1) was infused at a rate from 0.01 to 0.04 microgram.kg-1.min-1 to maintain a stable heart rate and stable systemic blood pressure. The anesthetic effects were excellent in both patients. The necessary concentration of propofol during anesthesia was 2.5 to 4.0 micrograms.ml-1, and the emergence concentration of propofol was 1.4 to 1.7 micrograms.ml-1. These values were almost equal to those obtained in patients without thyroid disease. In conclusion, we could maintain the anesthesia for the patients with hyperthyroidism safely and stably by titrating the concentration of propofol and fentanyl based on the BIS value, and by administrating propranolol and PGE1 to avoid hypertension and tachycardia.
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PMID:[Anesthetic management with propofol, fentanyl TCI and BIS in two cases of secondary hyperthyroidism due to TSH secretion from pituitary adenomas]. 1367 75

Sleep loss due to voluntary bedtime curtailment has become a hallmark of modern society. Even though sleep deprivation in rodents has been shown to result in death, it was until a few years ago thought that sleep loss results in increased sleepiness and decreased cognitive performance but has little or no adverse effects on human health. We measured sleep and 24-hour hormonal profiles in 11 healthy young males after 6 days of sleep restriction (4-hour bedtime) and after 6 days of sleep recovery (12-hour bedtime). At the end of sleep restriction, we observed reduced amounts of slow wave sleep (SWS) and rapid eye movement (REM) sleep and an alteration in the temporal distribution of these sleep stages, i.e. an increased pressure for REM sleep at the beginning of the sleep period and a decrease in the amount of slow wave activity (SWA) during the first sleep cycle. These later abnormalities are usually observed in depression. In addition, numerous alterations in the 24-hour hormonal profiles were observed in the state of sleep debt. The amount of melatonin secreted was reduced because of a delay in the onset of the nocturnal secretion and a reduction in the value of the acrophase. If the overall 24-hour cortisol profile was preserved, sleep restriction was associated with increased cortisol levels in late afternoon and evening hours and the duration of the quiescent period was reduced. The 24-hour mean TSH levels were reduced and the nocturnal TSH elevation was markedly dampened, most likely as a result of elevated levels of thyroid hormones. The acrophase of the 24-hour leptin profile occurred earlier, the amplitude of the rhythm and the overall mean levels were reduced. The nocturnal elevation of prolactin levels was abrupt but of short duration and the 24-hour mean levels were decreased. A pulse of growth hormone occurred prior to sleep onset, therefore affecting SWA distribution at the beginning of the sleep period. Since these alterations are qualitatively and quantitatively similar to those observed during aging and sometimes during depression, a state of sleep debt, as is experienced by a substantial fragment of the population in modern societies, is likely to increase the severity of depression and widespread age-related chronic conditions such as obesity, diabetes and hypertension.
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PMID:[Impact of sleep debt on physiological rhythms]. 1464 94

We report a 45-year-old woman with Cushing's syndrome showing reversible pituitary dysfunction. Left adrenal tumor was incidentally discovered by a screening examination of abdominal computed tomography. Although this patient lacked typical Cushingoid features except hypertension and leg edema, endocrine examinations revealed moderate suppression of plasma ACTH (~6.3 pg/ml) with relatively high levels of serum cortisol (~22.9 microg/dl) without normal circadian rhythm. Plasma ACTH failed to respond to either CRH or metyrapone, and dexamethasone failed to suppress her daily steroid production. Surgical removal of left adrenocortical adenoma and 6-month replacement of hydrocortisone have ameliorated both ACTH and cortisol responses to CRH loading test. Postoperative responses of TSH and GH to TRH and GRH, respectively, were two fold higher than the preoperative levels. In contrast, basal and TRH-induced levels of serum PRL were decreased after surgery although both the basal and stimulated PRL levels were markedly high before surgery. In addition, gonadotropin response to GnRH examined in the same ovarian cycle was decreased in accordance with an increase in serum estradiol and progesterone levels after surgery. Improvement of hypercortisolemia even in a moderate case of Cushing's syndrome not only ameliorates hypertension, obesity and glucose intolerance, but also restores the accompanying dysfunctions of anterior pituitary, suggesting the clinical importance of early discovery and treatment of functioning adrenocortical incidentalomas.
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PMID:Reversible pituitary dysfunction in a patient with Cushing's syndrome discovered as adrenal incidentaloma. 1511 71

Overt and subclinical hypothyroidism are associated with increased systemic vascular resistance and hypertension. We examined the relationship between thyroid function and blood pressure homeostasis in euthyroid individuals. A total of 284 subjects (68% hypertensive) consumed high- (200 mmol) and low- (10 mmol) sodium diets, and their blood pressure responses were assessed as percentage change in the mean arterial pressure (MAP). p-Aminohippuric acid clearance was used to estimate effective renal plasma flow. Renal vascular resistance (RVR) was calculated as MAP divided by effective renal plasma flow. Serum free T(4) index (FTI) was lower (P < 0.0001) and TSH was higher (P = 0.046) in hypertensive compared with normotensive subjects independent of other baseline characteristics. FTI (beta = -1.51, P < 0.0001), baseline MAP, and race independently predicted MAP salt sensitivity. The FTI relationship with salt sensitivity adjusted for baseline MAP and race was similar among normotensive (beta = -1.42, P = 0.008) and hypertensive subjects (beta = -1.66, P = 0.0001). FTI correlated negatively with high- (P = 0.0001) and low- (P = 0.008) salt RVR, whereas TSH correlated positively with high- (P = 0.016) and low- (P = 0.012) salt RVR independent of age, gender, race, and body mass index. We have found that FTI is lower and TSH is higher in hypertensive compared with normotensive euthyroid subjects and that FTI independently predicts blood pressure salt sensitivity. These data show that the influence of thyroid function on blood pressure homeostasis extends into euthyroid range and likely reflects the action of thyroid hormone on peripheral vasculature.
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PMID:Thyroid function and blood pressure homeostasis in euthyroid subjects. 1524 Jun 31

The cardiovascular risk in patients with hypothyroidism is related to an increased risk of functional cardiovascular abnormalities and to an increased risk of atherosclerosis. The pattern of cardiovascular abnormalities is similar in subclinical and overt hypothyroidism, suggesting that a lesser degree of thyroid hormone deficiency may also affect the cardiovascular system. Hypothyroid patients, even those with subclinical hypothyroidism, have impaired endothelial function, normal/depressed systolic function, left ventricular diastolic dysfunction at rest, and systolic and diastolic dysfunction on effort, which may result in poor physical exercise capacity. There is also a tendency to increase diastolic blood pressure as a result of increased systemic vascular resistance. All these abnormalities regress with L-T4 replacement therapy. An increased risk for atherosclerosis is supported by autopsy and epidemiological studies in patients with thyroid hormone deficiency. The "traditional" risk factors are hypertension in conjunction with an atherogenic lipid profile; the latter is more often observed in patients with TSH >10 mU/L. More recently, C-reactive protein, homocysteine, increased arterial stiffness, endothelial dysfunction, and altered coagulation parameters have been recognized as risk factors for atherosclerosis in patients with thyroid hormone deficiency. This constellation of reversible cardiovascular abnormalities in patient with TSH levels <10 mU/L indicate that the benefits of treatment of mild thyroid failure with appropriate doses of L-thyroxine outweigh the risk.
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PMID:Hypothyroidism as a risk factor for cardiovascular disease. 1524 98

Cushing's syndrome is characterized by endogenously increased production of glucocorticoids. The activity of immune system is regulated mainly by two systems in the body. Glucocorticoids and NF-kappaB counteract the effects of each other on the immune system. It has been reported that immune response is exaggerated after the amelioration of Cushing's syndrome. We report a rare case of exacerbation of Graves' disease after unilateral adrenalectomy for Cusing's syndrome. A 50-yr-obese woman with hypertension, dyslipidemia, impaired glucose tolerance and insulin resistance wasadmitted to outpatients clinic of endocrinology. The results of evaluation of glucocorticoids metabolism and adrenal magnetic resonance imaging revealed the Cusing's syndrome. We also assessed thyroid function tests because of the diagnosis of goiter and thyroid hormone replacement in her medical history, and the presence of exophthalmia and tachycardia in examination. Althoug TSH level was detected at the lower border of normal range, free T4 and free T3 were in normal range and autoantibody of thyroidal peroxidase and thyroglobulin was higer than normal reference range. An operation was performed and a mass was removed from her left adrenal gland. The pathologic examination confirmed adrenal adenoma. She was re-admitted to the outpatient clinic 9 months after with complaints of palpitation, malaise and weight loss. Tests carried out to determine the thyroid function revealed Graves' disease. We prescribed propylthiouracil and beta-blocker treatment.
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PMID:Exacerbations of Graves' disease after unilateral adrenalectomy for Cushing's syndrome. 1571 57

Pulse wave velocity (PWV) is known to represent arterial stiffness and is established as a marker for cardiovascular risk and a prognostic factor for mortality in the case of chronic renal failure or hypertension. The application of an automated apparatus for measuring brachial-ankle pulse wave velocity (baPWV) has made PWV measurement non-invasive, easier to screen for cardiovascular risk and as a result, baPWV measurements have become widely applied in clinical practice in recent years. We assessed the baPWV in 7 flank hypothyroidism patients and 28 subclinical hypothyroidism patients. In comparison with age matched healthy controls, 3 hypothyroid patients had advanced values and by replacement therapy, all 7 subjects showed improvement in their baPWV values (1531.2 +/- 242.7 to 1330.2 +/- 208.6 cm/s, p<0.05). In 28 subclinical hypothyroid subjects, 71% also had accelerated baPWV values for their age. Ten subjects (36% of all) had neither hypertension, hyperlipidemia, diabetes nor were taking any medication, and yet 8 patients out of 10 showed advanced baPWV values compared to age matched mean values. The baPWV was not correlated to TSH or total cholesterol levels, and was associated with only age and blood pressure (p = 0.01, <0.001, respectively), which are widely demonstrated as the characteristics for baPWV. In two subclinical hypothyroid subjects, who were normotensive and had no dyslipidemia, thyroxine treatment was performed and the baPWV decreased with unchanged blood pressure and total cholesterol levels. We concluded that the arterial wall stiffness tends to be increased in both overt and subclinical hypothyroid patients, and an appropriate treatment could reverse the abnormalities. It is possible that the initiation of adequate treatment in subclinical hypothyroidism may reduce the cardiovascular risk.
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PMID:Increased risk for atherosclerosis estimated by pulse wave velocity in hypothyroidism and its reversal with appropriate thyroxine treatment. 1575 64

Thyrotropin (TSH)-releasing hormone (TRH) also known as thyroliberin was the first of a number of peptides exerting several roles as a hormone and as a neuropeptide. Its ubiquitous distribution in the hypothalamus and in the extrahypothalamic regions and its diverse pharmacological and physiological effects are all features of its dual functions. For this reason, TRH has been the subject of much research throughout the past 20 years, work that has examined the structure, function, distribution, and regulation of the tripeptide and it has been extensively reviewed elsewhere [O'Leary R., O'Connor B. Thyrotropin-releasing hormone. J Neurochem. 1995;65:953-963.; Nillni E., Sevarino K. The biology of pro-thyrotropin-releasing hormone-derived peptides. Endocrine Reviews, 1999;20:599-664.]. After a brief overview of its distribution, hypothalamic and extrahypothalamic functions, and receptors involved, this review discusses efforts devoted to support TRH role in cardiovascular regulation with a main focus on hypertension pathophysiology in experimental models and humans.
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PMID:Thyrotropin-releasing hormone in cardiovascular pathophysiology. 1583 33


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