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

Isotretinoin (Accutane) is a drug closely related to the chemical structure of Vitamin A. The pharmacology and toxicology of these two retinoids is similar enough to warrant comparison. Accutane is a powerful drug which its manufacturer, Roche, indicates is limited for severe recalcitrant nodular acne. This potency is also reflected in Accutane's well-known ability to produce severe birth defects if taken during pregnancy. Less well-known is the risk of this lipid soluble chemical to affect the Central Nervous System. Reports of intracranial hypertension, depression, and suicidal indeation with Accutane use have prompted an examination of this serious and life threatening potential. Though Roche has added a warning to its product label for signs of depression and suicidal ideation, this product is being overprescribed for all forms of acne, including mild cases and moderate acne that have not been treated with alternative medications, which have a lesser risk of depression and suicide. There is no contesting that this drug is effective at clearing up the most severe forms of acne, but the public must be informed of its proper, limited indication for use; depression and suicide can follow in patients with no prior history of psychiatric symptoms or suicide attempts.
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PMID:Polar hysteria: an expression of hypervitaminosis A. 1554 93

It has been suggested that increased oxidative stress may be both a cause as well as a consequence of hypertension. In vivo oxidation of low-density lipoproteins by oxygen-free radicals may increase hypertension-related atherogenesis, and antioxidants may be beneficial in this regard. Previous findings concerning associations between serum measures of antioxidants and hypertension have however been inconsistent. Plasma levels of beta-carotene, Vitamin A, E, uric acid, homocysteine and total antioxidant capacity, as well as two markers of oxidative stress, malondialdehyde (MDA) and protein carbonyls, were measured in morning fasting blood samples provided by 415 Australians aged 60-64 years, selected randomly from the community. Participants also provided information on sociodemographic attributes, mental and physical health, and provided two measures of resting blood pressure, allowing a diagnosis of definite or borderline hypertension. Those with hypertension had lower levels of beta-carotene and higher levels of uric acid and MDA compared to normotensive participants. The last two of these associations persisted when the analyses controlled for lifestyle and health factors. The findings from this study offer limited support for the proposition that lower antioxidant status and higher oxidative stress are associated with hypertension, and suggest the need for longitudinal studies to examine causality and intervention studies to determine the benefit of antioxidants in this group.
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PMID:Associations between plasma antioxidants and hypertension in a community-based sample of 415 Australians aged 60-64. 1557 48

Studies using a model of non-infectious diarrhea, have shown that increasing fecal mass by using laxatives resulted in greater fecal losses of nutrients and lower intestinal absorption. In the present study we used a diuretic to determine if increasing urine volume could result in greater urinary losses of essential nutrients. This is a relevant question because diuretics are widely and successfully used in the treatment of diseases associated with water retention and hypertension. They are known to increase potassium losses. However, there is less information on the effect of diuretics on the urinary losses of essential nutrients. Accordingly, urinary nitrogen, phosphorous, sodium, potassium, magnesium, zinc and retinol were measured in young rats consuming increasing concentrations of furosemide (0, 0.5, 1.0, 1.5 mg/g diet) in the diet over 15 days. The results showed that dietary furosemide caused a dose-dependent polyuria. In addition it reduced food intake and feed efficiency and leaded to poor growth and greater urinary losses of all the measured nutrients and electrolytes. These losses were proportional to urine volume and represented an important fraction of the rats daily intake. The losses were negatively associated with the body and liver content of the same electrolytes and nutrients. In general, this study showed that the diuretic furosemide caused malnutrition in a short period of time by reducing food intake as well as the capacity of retaining macro and micronutrients including the liposoluble vitamin A in a relatively short period of time. This study, together with our previous studies on diarrhea, indicate that proper nutrient utilization requires both an adequate intestinal and renal function.
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PMID:Effect of the diuretic furosemide on urinary essential nutrient loss and on body stores in growing rats. 1633 25

A technique was developed to record intracranial cerebrospinal fluid pressure (iCSFp) in chicks and mature chickens. Using that procedure, 2 methods were found to effect a significant elevation in intracranial pressure: 1) feeding a purified diet to roosters for 40 d containing 25% of the bird's requirement for vitamin A, and 2) ligating both jugular veins in birds. The purified diet significantly reduced plasma retinol levels from 1.080 to 0.046 microg/mL, and iCSFp was significantly elevated from 63.0 to 106.0 mmH2O (P < or = 0.05). Two limitations for using hypovitaminosis A diets were capillary fragility and a cisterna magna that did not develop to the size of that structure in birds of the same age fed control diets with adequate vitamin A content. The second procedure, a reversible surgical technique, showed that within 2.5 h from jugular vein ligation, intracranial pressure rose to 109.7 mmH2O, comparable with levels attained following feeding a vitamin A deficient diet to roosters. Bilateral clamping of the jugular veins overnight resulted in an elevation of iCSFp to 127 +/- 8.86 mmH2O. Results suggest that the chicken may be a useful animal model to investigate intracranial hypertension and its accompanying headaches known to occur in humans.
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PMID:The use of vitamin A-deficient diets and jugular vein ligation to increase intracranial pressure in chickens (Gallus gallus). 1655 86

Nephron endowment ranges widely in normal human populations. Recent autopsy studies have drawn attention to the possibility that subtle congenital nephron deficits may be associated with increased risk of developing hypertension later in life. Since modest maternal vitamin A deficiency reduces nephron number in rats, we designed a pilot study to determine the prevalence of maternal vitamin A deficiency in Montreal (Canada) and Bangalore (India) and the usefulness of newborn renal volume as a surrogate for nephron endowment. Among 48 pregnant Montreal women, two (4%) had one isolated mid-gestation retinol level slightly below the accepted limit of normal (0.9 mumol/L), whereas 25 (55%) of 46 pregnant women in Bangalore had at least one sample below this limit. Average estimated retinoid intake was correlated with mean serum retinol in pregnant women from Bangalore. In Montreal where maternal vitamin A deficiency was negligible, we found that newborn renal volume (estimated by renal ultrasonography at 2-6 weeks of age) was correlated with surface area at birth and was inversely correlated with serum creatinine at 1 month. Interestingly, renal volume adjusted for body surface area in Montreal (184+/-44 ml/m(2)) was significantly greater than in Bangalore (114+/-33 ml/m(2)) (p<0.01). Definitive studies are needed to establish whether maternal vitamin A deficiency accounts for subtle renal hypoplasia in Indian newborns. If so, there may be important public health implications for regions of the world where maternal vitamin A deficiency is prevalent.
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PMID:Effects of maternal vitamin A status on kidney development: a pilot study. 1709 88

The aim of the study was to investigate the effects of cytoprotectional drug Mildronate ("Grindex", Latvia) on some parameters of oxidative processes and endothelial function in elderly patients with coronary heart disease (CHD). One hundred seventeen elderly CHD patients were included into controlled study. The criteria to include the patients into the study were: men and women upwards 60 years old with CHD, with heart failure FC II or III (in accord, NYHA classification), with arterial hypertension (AH), without diabetes mellitus. All patients were randomized into 2 groups: 1) 67 patients 75.4 +/- 0.5 years old were treated with Mildronate 500 mg/day against traditional basal therapy during 12 weeks (the main group) and 2) 50 patients 74.0 +/- 0.6 years old were treated only traditional basal therapy during 12 weeks (the compare group). The blood lipid profile parameters, such as total cholesterol (CH), triglycerides (TG), low density lipoprotein cholesterol (LDL-CH), high density lipoprotein CH (HDL-CH), LDL antioxidant potential (concentration of alpha-tocopherol and retinol in LDL), initial level of lipid peroxidation (LPO) products in LDL, LDL resistance to oxidation in vitro and the blood level of NO metabolites were evaluated before and after 4 and 12 weeks of the study. Effect of Mildronate on the blood lipid profile parameters in elderly CHD patients was not revealed. The initial level of LPO products in LDL was decreased and LDL resistance to oxidation in vitro was increased in main group patients after 12 weeks of study in comparison with the same parameters before the study and with compare group patients (p < 0.05). The blood level of NO metabolites was 1.5-fold higher in main group patients after 12 weeks of study in comparison with the same parameters before the study and with compare group patients (p < 0.05). Thus, in elderly CHD patients the several antiatherogenic effects of Mildronate, such as the decreasing activity of LPO processes in LDL and the increasing synthesis/secretion of blood NO, were revealed.
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PMID:[Effect of cytoprotection on the oxidative processes and endothelial function in elderly patients with ischemic heart disease]. 1715 32

Vitamin A (retinol) and its analogs (retinoids) are important regulators of cell proliferation, differentiation, immune function, and apoptosis. The kidneys are target organs for vitamin A action. Retinoic acid (RA), a vitamin A metabolite, is involved in embryonic kidney patterning through the control of receptor tyrosine kinase expression, which modulates ureteric bud branching morphogenesis. Vitamin A status of the mother profoundly affects kidney organogenesis of the newborn. In rodents, mild vitamin A deficiency results in a 20% reduction of nephron number. In adult humans, nephron number varies between 0.3 and 1.3 million per kidney, which is accepted as normal. However, recent studies indicate that humans at the low end of nephron number are predisposed to primary hypertension. Because RA regulates nephron mass, its optimal availability during nephrogenesis is critical. RA levels in the embryo are affected by several factors, such as maternal vitamin A nutrition and disturbances in retinol metabolism. Maternal vitamin A deficiency during pregnancy is widespread in developing countries and segments of these populations may be exposed to low vitamin A during fetal life when nephron number is determined. Infants are likely to be born with suboptimal nephrons and may develop primary hypertension later in life. Although maternal vitamin A deficiency is not common in developed countries, congenital nephron number nevertheless varies widely, indicating low fetal RA levels due to common variants of the enzymes that convert retinol to RA. These infants might require heightened surveillance for hypertension later in life.
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PMID:Role of vitamin A in determining nephron mass and possible relationship to hypertension. 1864 Nov 82

Obstructive sleep apnea syndrome (OSAS) is related to the increased prevalence of cardiovascular disease and metabolic syndrome (MS). A novel adipokine, retinol binding protein-4 (RBP4), was reported to be associated with insulin resistance and the prevalence of type 2 diabetes. To examine whether plasma RBP4 is associated with insulin resistance and MS development in OSAS, we measured plasma RBP4 levels in 181 Japanese men (24 healthy controls and 40 mild, 64 moderate, and 53 severe OSAS) of whom 26 had mild glucose intolerance with HbA1c < or = 6.0%. After a full polysomnography, blood was collected between 06:00 and 07:00 AM. Plasma RBP4 levels in moderate/severe OSAS patients were higher than in control subjects. Plasma RBP4 was not correlated with apnea variables, HOMA-IR, or blood pressure. However, it was positively correlated with visceral fat areas and plasma triglyceride levels. The prevalence of MS was higher in severe OSAS patients than in mild/moderate OSAS and control subjects. Plasma RBP4 was higher in OSAS patients with MS than in those without MS. This study indicates that plasma RBP4 is associated with dyslipidemia, but not with insulin resistance, glucose intolerance, or hypertension in patients with OSAS. Visceral obesity may play key roles in increasing the plasma RBP4 level and MS development in OSAS.
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PMID:Visceral obesity is associated with the metabolic syndrome and elevated plasma retinol binding protein-4 level in obstructive sleep apnea syndrome. 1900 25

Unlike pharmacological agents that are taken for proscribed periods of time, food and nutrient intakes have the possibility of affecting bone health over the entire lifespan. While deficiencies or excesses of individual nutrients have been shown to affect bone, it is likely that individual foods or dietary patterns have important effects related to skeletal health. While biochemical mechanisms exist to relate a deficiency of vitamin K to altered bone metabolism, clinical trials related to supplementation of this nutrient have been confusing. It is likely that these disparate results are related to the fact that interactions of nutrients have not been considered or the possibility that suboptimal nutrient status is a marker of poor nutritional status. Vitamin A excess has been postulated to be related to high fracture risk; however, it is likely that retinol is not the best marker for the proposed interaction. Altering whole food patterns, such as the Dietary Approaches to Stop Hypertension diet, have demonstrated beneficial effects on bone metabolism. Individuals who select some vegetarian patterns may need to consider supplementation with nutrients such as calcium and protein. Future studies should center on whole food and dietary patterns and their relationship to bone metabolism and fracture risk.
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PMID:Nutrition and bone: it is more than calcium and vitamin D. 1986 75

The heavy metal cadmium (Cd) is known to be a widespread environmental contaminant and a potential toxin that may adversely affect human health. Exposure is largely via the respiratory or gastrointestinal tracts; important non-industrial sources of exposure are cigarette smoke and food (from contaminated soil and water). The kidney is the main organ affected by chronic Cd exposure and toxicity. Cd accumulates in the kidney as a result of its preferential uptake by receptor-mediated endocytosis of freely filtered and metallothionein bound Cd (Cd-MT) in the renal proximal tubule. Internalised Cd-MT is degraded in endosomes and lysosomes, releasing free Cd(2+) into the cytosol, where it can generate reactive oxygen species (ROS) and activate cell death pathways. An early and sensitive manifestation of chronic Cd renal toxicity, which can be useful in individual and population screening, is impaired reabsorption of low molecular weight proteins (LMWP) (also a receptor-mediated process in the proximal tubule) such as retinol binding protein (RBP). This so-called 'tubular proteinuria' is a good index of proximal tubular damage, but it is not usually detected by routine clinical dipstick testing for proteinuria. Continued and heavy Cd exposure can progress to the clinical renal Fanconi syndrome, and ultimately to renal failure. Environmental Cd exposure may be a significant contributory factor to the development of chronic kidney disease, especially in the presence of other co-morbidities such as diabetes or hypertension; therefore, the sources and environmental impact of Cd, and efforts to limit Cd exposure, justify more attention.
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PMID:Heavy metal poisoning: the effects of cadmium on the kidney. 2035 61


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