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 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Calcium is the fifth most abundant element in the earth's crust and is necessary for both plant and animal life today. Moreover, the natural diets of all mammals are rich in calcium. The diet of Stone Age human adults is estimated to have contained from 50 to 75 mmol of calcium (2000 to 3000 mg)/d, three to five times the median calcium intake of present-day US adults. Human physiology has adapted to this environmental abundance with an intestinal absorptive barrier and inefficient renal conservation of calcium. Although mammalian physiology contains mechanisms by which organisms can adjust to temporary environmental shortages, chronic calcium retention has a number of health consequences, most notably bone fragility, high blood pressure, and colon cancer. Evidence indicates that improvement in calcium intake (or in vitamin D status) prevents some portion of each of these multifactorial problems. At least 14 intervention studies have established the skeletal benefit of increased calcium intake during growth and among women in the late postmenopause. Other evidence suggests that adequate calcium may protect against salt-sensitive and pregnancy-associated hypertension and that high intakes of both dietary calcium and vitamin D reduce development of precancerous changes in colonic mucosa.
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PMID:ADSA Foundation Lecture. Low calcium intake: the culprit in many chronic diseases. 804 60

This paper examines the evidence that connects calcium intake and vitamin D status to bone fragility, hypertension, colon cancer, and breast cancer. Human calcium physiology, with an intestinal absorptive barrier and inefficient conservation, reflects the abundance of calcium in the primordial human food supply. The calcium intake of stone-age adults is estimated at 50 to 75 mmol/d, three to five times the median calcium intake of present-day U.S. adults. Long-term calcium restriction and/or insufficient vitamin D may promote the development of bone fragility, high blood pressure, colon cancer, and breast cancer in susceptible individuals. Conversely, improvement in calcium intake and/or in vitamin D status may help to prevent these serious health problems. At least 12 intervention studies have established the skeletal benefit of increased calcium intake among women in the late postmenopause. Other reports suggest that adequate calcium may protect against salt-sensitive and pregnancy-associated hypertension. High intakes of both dietary calcium and vitamin D are associated with reduced development of precancerous changes in colonic mucosa. Preliminary findings also suggest that vitamin D has a protective effect against breast cancer.
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PMID:The role of calcium intake in preventing bone fragility, hypertension, and certain cancers. 806 93

Besides defining the appropriate doses of frusemide in uraemic patients, A. Heidland's contribution to the treatment of hypertension in chronic renal failure consisted in the following demonstrations: (1) In patients on chronic haemodialysis, calcium antagonists have a beneficial effect on their glucose intolerance and decreased plasma levels of 25OH vitamin D while their effect on blood lipids is neutral. (2) In 5/6 nephrectomized rats, captopril, verapamil, and metoprolol have the same protective effect on their GFR and tubular secretion of protons, at equal blood-pressure-lowering effect. (3) In rats with streptozotocin-induced diabetes, atrial natriuretic peptide does not play a role in their hyperfiltration. (4) Severe retinopathy is observed in patients with uraemic nephropathies at a much smaller elevation of their blood pressure than in patients with essential hypertension. This article reviews the following points: (1) The role of hypertension in the loss of renal function is convincingly demonstrated only in a few experimental models, and in man only in malignant hypertension and diabetic nephropathy but not in essential hypertension nor in non-diabetic nephropathy. However, preliminary results suggests that antihypertensive treatment may retard the progression of renal disease in normotensive patients (DBP <90 mmHg) with either microalbuminuric diabetes and normal renal function or non-diabetic uraemic nephropathy. (2) Only the ACE inhibitors have been proved to have a specific renal protective effect, independent of their diurnal blood-pressure-lowering effect, both in diabetic nephropathy and in non-diabetic uraemic nephropathy.
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PMID:Hypertension and progression of renal insufficiency. 807 21

Glucocorticoids are highly valuable medication available to a physician, yet, their serious side effects have severely limited their use. Thus, the major purpose of our review is to provide a practical approach to increasing efficacy and minimizing side effects, that is increasing the benefit/risk ratio, of glucocorticoid therapy. The most effective way of avoiding their side effects, including infection, osteoporosis, atherosclerosis, is simply to avoid the overuse of glucocorticoids and to restrict their use to the truly indicated disease. Side effects can be reduced in part by the development of drug delivery systems, such as topical administration and targeting therapy. Combinations of calcium, vitamin D and sometimes thiazide or calcitonin, as compensatory therapy, have shown some favorable results for the prevention of osteoporosis. Although glucocorticoid therapy causes an increase of high-density lipoprotein and a decrease of lipoprotein (a) in serum, both are possibly preventive for atherosclerosis, hypertension and diabetes mellitus which are risk factors of atherosclerosis should be controlled. Future trends to remove their side effects will be obtained by more specific therapy based upon their pathogenesis.
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PMID:[Minimizing side effects of glucocorticoid therapy]. 816 80

The menopause is defined as cessation of menstruation, ending the fertile period. The hormonal changes are a decrease in progesterone level, followed by a marked decrease in estrogen production. Symptoms associated with these hormonal changes may advocate for hormonal replacement therapy. This review is based on the English-language literature on the effect of estrogen therapy and estrogen plus progestin therapy on postmenopausal women. The advantages of hormone replacement therapy are regulation of dysfunctional uterine bleeding, relief of hot flushes, and prevention of atrophic changes in the urogenital tract. Women at risk of osteoporosis will benefit from hormone replacement therapy. The treatment should start as soon after menopause as possible and it is possible that it should be maintained for life. The treatment may be supplemented with extra calcium intake, vitamin D, and maybe calcitonin. Physical activity should be promoted, and cigarette smoking reduced if possible. Women at risk of cardiovascular disease will also benefit from hormone replacement therapy. There is overwhelming evidence that hormone therapy will protect against both coronary heart disease and stroke, and there is no increased risk of venous thrombosis or hypertension. A disadvantage of hormone replacement therapy is an increased risk of forming gall-bladder stones and undergoing cholecystectomy. Unopposed estrogen therapy gives a higher incidence of endometrial cancer in women with an intact uterus, but the contribution of progestins for about 10 days every month excludes this risk. Breast cancer in relation to estrogen-progestogen therapy has been given much concern, and the problem is still not fully solved. If there is a risk, it is small, and only after prolonged use of estrogen (15-20 years). The decision whether or not to use hormone replacement therapy should, of course, be taken by the individual woman in question, but her decision should be based on the available scientific information. It is the opinion of the authors that the advantages of hormone replacement therapy far exceed the disadvantages. We suggest that every woman showing any signs of hormone deprivation should be treated with hormone replacement therapy. This includes women with subjective or objective vaso-motor symptoms, genito-urinary symptoms, women at risk of osteoporosis (fast bone losers), and women at risk of cardiovascular diseases.
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PMID:Postmenopausal hormone replacement therapy--clinical implications. 819 55

In order to know if abnormalities of calcium metabolism may be involved in the pathophysiology of pregnancy-induced hypertension (PIH), as it has been incriminated in essential hypertension, we measured plasma and urinary calcium and phosphate as well as plasma PTH and free calcitriol index (ratio of total calcitriol on the D binding protein) in normotensive pregnant women (n = 25), in women with PIH after the same duration of amenorrhea (> 28 wk, n = 21:preeclampsia and 20 transient hypertensions), and in age-matched nonpregnant women (n = 15). The severity of PIH was mild since blood uric acid was not increased and plasma volume, measured with the Evans blue technique, was found only moderately decreased (-10.5 +/- 3.1% of normal value). The results show that normotensive pregnant women showed the expected increase of the vitamin D parameters in comparison to nonpregnant controls. Hypertensive pregnant women were not different from the normotensive ones regarding plasma corrected calcium and phosphate and urinary excretion of calcium and phosphate, but had higher plasma PTH (13 +/- 1 v 8.8 +/- 1.6 pg/mL) and lower total and free calcitriol index (86 +/- 7 v 110 +/- 6 pg/mL and 1.72 +/- 0.10 v 2.25 +/- 0.13 x 10(-5)). Correlative studies showed PIH having a negative correlation between blood pressure and plasma corrected calcium (r = -0.43, P < .05), which is in agreement with epidemiological studies of essential hypertension. In conclusion, disturbances of calcium regulating hormones do exist in transient forms of pregnancy-induced hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Calcium metabolism, plasma parathyroid hormone, and calcitriol in transient hypertension of pregnancy. 834 36

To clarify the effects of active vitamin D3 on pressor and vascular responses to vasoconstrictor substances, we studied pressor responses to the intravenous injection of norepinephrine or angiotensin II (Ang II) and vasoconstrictor responses to norepinephrine. Sprague-Dawley rats were given 1,25-dihydroxyvitamin D3 subcutaneously (200 ng/kg per day) for 14 days. The administration of 1,25-dihydroxyvitamin D3 augmented the pressor responses to norepinephrine and Ang II in conscious rats and was associated with a significant increase in serum calcium concentration (11.0 +/- 0.2 mg/dl). To further clarify whether the increased pressor response to vasoconstrictors may be due to the calcemic or direct action of active vitamin D3, we studied the effect of its noncalcemic analogue, 22-oxacalcitriol, and its inactive analogue, 24,25-dihydroxyvitamin D3, on the pressor response to vasoconstrictors in rats. The pressor responses to norepinephrine and Ang II were apparently augmented in 22-oxacalcitriol-treated rats similarly to 1,25-dihydroxyvitamin D3-treated rats. In contrast, the pressor responses were not affected by either 24,25-dihydroxyvitamin D3 or the intravenous infusion of calcium chloride. In an ex vivo experiment using a mesenteric preparation, the vascular sensitivity to norepinephrine was moderately augmented in rats treated with both 22-oxacalcitriol and 1,25-dihydroxyvitamin D3 but was not affected in rats treated with 24,25-dihydroxyvitamin D3. The results suggest that the enhanced pressor responses to norepinephrine and Ang II could be attributed to the direct effect of active vitamin D3 on vasculature rather than to hypercalcemia.
Hypertension 1993 Feb
PMID:Enhancement of vasoconstrictor response by a noncalcemic analogue of vitamin D3. 842 88

To investigate possible relationships between hyperparathyroidism, alterations in intracellular free calcium concentration ([Ca2+]i) and hypertension in chronic renal failure, serum concentrations of intact parathyroid hormone (PTH) were measured by two-site immunometric assay, and platelet ([Ca2+]i) was assessed using the fluorescent indicator fura-2. Thirty-six patients with chronic renal failure were studied, 10 with normal serum PTH concentrations (mean 8.0 +/- 0.6 pmol/liter), 17 with elevated serum PTH (35.0 +/- 7.2 pmol/liter) and 9 patients with elevated PTH (36.2 +/- 5.9 pmol/liter) who were receiving nifedipine. Platelet [Ca2+]i was increased in patients with elevated PTH, compared with those in whom PTH was normal (138 +/- 16 vs. 83 +/- 7 nmol/liter, P < 0.01). A linear relation was observed between serum PTH and platelet [Ca2+]i in these patients (r = 0.818, P < 0.001). In contrast, platelet [Ca2+]i was not elevated (84 +/- 9 nmol/liter) in the patients with elevated PTH who were receiving nifedipine. A linear relation was also present between both serum PTH (r = 0.616, P < 0.001) and platelet [Ca2+]i (r = 0.576, P < 0.005) and mean blood pressure. Nine patients with hyperparathyroidism were restudied after treatment with the vitamin D analogue alfacalcidol. This resulted in significant decreases in serum PTH (P < 0.01), platelet [Ca2+]i (P < 0.02), and mean blood pressure (P < 0.05). These studies indicate that [Ca2+]i may be increased early in renal failure, and that this increase occurs in association with both hyperparathyroidism and hypertension. Furthermore, treatment of hyperparathyroidism with alfacalcidol may result in reductions in both [Ca2+]i and blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hyperparathyroidism, platelet intracellular free calcium and hypertension in chronic renal failure. 845 69

To investigate the role of parathyroid hormone (PTH) in the development of hypertension, the long-term administration of human PTH (hPTH) was performed in 7-week-old male spontaneously hypertensive rats maintained on a standard calcium diet (1.1% calcium) or a high calcium diet (2.8% calcium). The hPTH was infused subcutaneously at 0.9 U/h over 2 weeks using a minipump. Two weeks after minipump implantation, rat PTH (rPTH) and 1,25-dihydroxy vitamin D (1,25-D) levels were measured and the pressor response to norepinephrine (NE) was examined. Calcium loading both attenuated the development of hypertension and reduced the pressor response to norepinephrine. Chronic hPTH administration accelerated the development of hypertension and increased the pressor response to norepinephrine in rats fed a high calcium diet, but did not affect either parameter in rats fed a standard calcium diet. The serum concentrations of rat PTH and 1,25-D were significantly lower in rats fed a high calcium diet than in those fed a standard calcium diet (rat PTH: 351 +/- 16 v 430 +/- 1 pmol/L; 1,25-D: 125 +/- 19 v 206 +/- 31 pg/mL). Chronic administration of hPTH increased the serum 1,25-D concentration in rats fed a high calcium diet (186 +/- 35 pg/mL), but did not affect that of rats fed a standard calcium diet (165 +/- 16 pg/mL). It is concluded that PTH prevented the antihypertensive effect of calcium loading in young SHR, perhaps by enhancing blood pressure reactivity through causing an increase of 1,25-D.
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PMID:Chronic parathyroid hormone administration reverses the antihypertensive effect of calcium loading in young spontaneously hypertensive rats. 846 11

Our views on paediatric nutrition have considerably changed during the last 20 years. Some hereditary metabolic diseases testify to the remarkable efficacy of a specific preventive dietetics avoiding the development of mental retardation. Although certain deficiencies (in iron, fluorine, folates, vitamin D) are persisting in France, the major problems concern the prevention in childhood of allergy, obesity, atherosclerosis, high blood pressure, osteoporosis and even certain cancers, all diseases which play a crucial role in the morbidity and mortality of adults. Numerous uncertainties still exist, but in the present state of our knowledge we can already develop some recommendations which should replace the much abusive publicity that prevails in the information given to the public.
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PMID:[Towards preventive dietetics in children]. 850 35


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