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

Perinatal deaths and perinatal mortality rates in Cape Town for the period 1967--1977 have been analysed, and large differences were found between the various ethnic groups. In non-Whites stillbirths accounted for more than two-thirds of perinatal deaths in 1977, and in at least 75% of these fetal death preceded labour. Perinatal mortality rates must be considered together with the number of perinatal deaths if the true magnitude of the problem with regard to the various obstetric complications and procedures is to be appreciated. The main perinatal problems as they affect the infant were (i) during pregnancy--antepartum haemorrhage (especially abruptio placentae), intra-uterine growth retardaton, multiple pregnancy, proteinuric hypertension and unbooked status; (ii) during labour and delivery--preterm labour, stillbirths (especially before labour) and vaginal breech delivery; (iii) in the early neonatnal period--immaturity and respiratory distress and neonatal infection.
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PMID:Trends in perinatal mortality in Cape Town, 1967--1977. 57 66

Several conclusions seem evident from this study : firstly radiation myelopathies exist without any doubt; secondly clinical observation, even very attentive, during irradiation is perfectly blind regarding this subject; lastly, one can only, at this time, attempt to anticipate medullary accidents caused by irradiation. Radiation myelopathies exist incontestably. We report 27 new cases which are added to the more than 500 cases already analysed in the world litterature. The improvement of results of cancerology and in particular of radiotherapy make and will continue to make the number of observations published increase. However, if there is no doubt as to existence of these myelopathies, discussions persist concerning their nature : purely vascular, cytotoxic, probably mixed, perhaps maintained and prolonged by a superimposed immunologic phenomenon. Prevention is the sole method at our disposal to be effective. It must be applied as much to the patient as to the technique of irradiation. With regard to the patient treated in a medullary volume, several factors are probably favorable to the development of myelopathy and must cause one to modify eventually the technique of radiation proposed : the existence of anterior vertebral medullary pathology, whatever its nature; two ages demonstrate increased incidences : the young which have relative immaturity of tissue (we report 4 cases patients less than 25 years old), and the old, whose chances of accumulating associated pathologies are great, especially as systemic hypertension and arteriosclerosis are likely to have played a favorable role; the patients for whom restraint is difficult or who present disrupted regions anatomy are qually much more fragile. With regard to the technical plan, several factors incontestably favor the appearance of radiation myelopathy : large medullary volumes irradiated, especially when they encompass the zones of vascular medullary junction; the overlap of fields involving the spinal cord; the reduction of fields too close to the spinal cord not allowing at least 1 cm margin of relative security; the association of physical agents in the measure to which the global dosimetry is uncertain, i.e. in particular the use of high energy electrons for boost dosage, the intensity of which must be chosen with the greatest prudence; finally and most importantly, it seems desirable to us not to surpass at the level of the spinal cord, treating 5 times per week, a dose of 5 000 rads with fractions of 200 rads of 4 500 rads with fractions of 250 rads, and of 4 000 rads with fractions of 300 rads. Can one reasonable pretend always to foresee all radiation myelopathies? No, for on the one hand there exist authentic cases which have occured after doses which were below the limits of tolerance which we have indicated above, in accordance with others authors, and on the other hand, the necessity of sterilising certain inoperable tumors obliges one sometimes to deliver to region of the spinal cord aggressive doses.
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PMID:[Late progressive radiation myelopathies. A study of 27 cases]. 81 47

Cases of sexual immaturity and male pseudohermaphroditism due to disorders such as androgen resistance, 5 alpha-reductase deficiency, cholesterol desmolase deficiency, 3 beta-hydroxysteroid dehydrogenase deficiency, and testicular and ovary dysgenesis can easily be distinguished from 17 alpha-OHD. None of these disturbances result in hypertension. In the only other form of juvenile hypertension due to congenital adrenal hyperplasia, 11 beta-OHD, androgen excess leads to female pseudohermaphroditism and precocious puberty in the male patient. Patients with dexamethasone-suppressible hyperaldosteronism present with no sexual abnormalities. A diagnosis of 17 alpha-OHD can be readily assumed in the female patient with primary amenorrhea, hypertension, and hypokalemia. The absence of aldosterone, a measurement that is readily available, establishes this diagnosis even without the measurement of DOC.
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PMID:17 alpha-hydroxylation deficiency. 187 98

Erythrocytosis and microcytosis have been described in strains of genetically hypertensive rats and in essentially hypertensive humans. Published discussion of these phenomena has centered around their relationship to observed alterations in ionic transport and the pathogenesis of hypertension. In presenting data for another strain of spontaneously hypertensive rats in which these findings are exhibited, we note that erythroid cell size decreases concurrently with the increase in cell numbers so that the hematocrit and the mean corpuscular hemoglobin concentration remain constant. Data from the literature support the hypothesis that erythroid cell size is inversely proportional to cell count in a large number of species. Erythrocytosis, as it develops in the neonatal rat, is a consequence of the marked immaturity of this species at birth. Erythrocytosis in the spontaneously hypertensive rat is not due to a difference in the affinity of its hemoglobin for oxygen or to significant tissue anorexia. Microcytosis in the spontaneously hypertensive rat is the consequence of a continuation of the linear volume decrease with age of its erythroid cells seen in the normotensive animals and may be accounted for by the production of smaller cells with concomitant regulation of individual cell volume.
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PMID:Inverse changes in erythroid cell volume and number regulate the hematocrit in newborn genetically hypertensive rats. 194 11

We compared blood pressure, hindquarter vascular resistance properties, left ventricular weight, and norepinephrine kinetics, in spontaneously hypertensive rats (SHR) and weight-matched normotensive Wistar-Kyoto (WKY) rats at 4, 9, 14, 20, 30, and 50 weeks of age. At 4 weeks, systolic and mean blood pressure measurements were the same in both strains, but the vascular resistance of the fully dilated hindquarter bed was significantly higher in SHR than in WKY rats, with a much larger difference during maximum constriction. Plots of resistance at maximum dilatation and at maximum constriction against body weight suggest that a component of the increase in vascular muscle mass in SHR occurred in the neonatal period preceding hypertension followed by a later component related to the rise in blood pressure. By contrast, left ventricular hypertrophy was minimal at 4 weeks and most of its development paralleled the rise in blood pressure. Sympathetic activity, assessed by norepinephrine fractional rate constant, was higher in SHR than in WKY rats in the left ventricle and kidney through most of the period between 4 and 50 weeks, but was similar in both strains in the muscle bed. This pattern of sympathetic activity will accentuate hypertension once cardiac and vascular hypertrophy are fully established. In all regions, norepinephrine tissue concentration was higher in young SHR and could potentiate the trophic effects of growth factors in early vascular hypertrophy. We suggest that the initial (primary) component of vascular hypertrophy precedes the rise in blood pressure and may be critical in the pathogenesis of hypertension. Possible reasons for the short delay in the rise in blood pressure in young SHR, once the vascular "amplifier" has been established, include high vascularity, immaturity of smooth muscle, and delay in the development of left ventricular hypertrophy.
Hypertension 1989 Aug
PMID:Differential development of vascular and cardiac hypertrophy in genetic hypertension. Relation to sympathetic function. 252 1

Hypertension is a pathological condition that involves maternal fetal relationship. In hypertension placenta displays a syncytiotrophoblast plasmalemma with aspects of anomalous behaviour concerning Intramembranous Particles (IMP) and actin content of microvilli cytoskeleton. Decrease of syncytiotrophoblast microvilli IMP and microvilli actin further sustain the tendency of hypertensive placenta to show some features of immaturity that might deeply influence fetal-maternal exchanges during pregnancy associated with pathological status.
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PMID:[Hypertension and syncytiotrophoblast: morpho-structural aspects]. 262 39

To evaluate the possible functional relationships between hypertensive status and syncythiotrophoblast plasma membrane behaviour we have carried out a freeze-fracturing and biochemical investigation to assess: 1) ultrastructurally, relations between number and diameter of Intramembrane Particles (IMP) and hypertensive conditions; 2) biochemically, actin content of microvilli in this pathological status. Our data in vitro show a decrease of IMP in hypertension before and after Ca++ addition and a decrease of actin in microvilli of hypertensive placenta. These observations seem to be in agreement with the hypothesis of a possible structural immaturity in hypertensive placenta and may represent morphological signs of placental insufficiency.
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PMID:Molecular alterations induced by hypertension in pregnancy on syncythiotrophoblast plasma membranes from human placenta. 263 67

The circulating levels of vasopressin, catecholamines and renin activity before, during and following a 10-20% fall in mean arterial blood pressure induced by sodium nitroprusside were measured in six chronically catheterized lambs during the first week of life. No significant changes in pHa, PaO2, PaCO2, Plasma sodium or osmolality were observed during or following the infusion of sodium nitroprusside at an average of 12 g.kg-1.min-1 (table I). However, the fall in blood pressure at the end of 60 minutes infusion, was associated with significant increases in the plasma levels of vasopressin from a control value of 2.4 +/- 0.57 to a maximum of 35.1 +/- 16.3 pg/ml (p = .002), renin activity from 6.7 +/- 1.56 to 27.4 +/- 11.44 ng.ml-1.hr-1 (p = .003), and catecholamines from 189.3 +/- 42.15 to 543.3 +/- 100.52 pg.ml-1 (p = .0001). The increase in vasopressin is lower, while that of PRA was higher and catecholamines similar to those found in the ewe. Plasma renin activity (PRA) and catecholamine levels remained elevated for at least 30 minutes following the end of the infusion while the mean blood pressure rose significantly above control levels and remained elevated for twenty minutes. We speculate that the persistent elevated levels of vasoactive mediators are responsible for the prolonged rebound hypertension following the cessation of the nitroprusside infusion and is the result of an immaturity of either a feedback process or metabolism of the vasoactive mediators or a combination of both mechanisms. This rebound hypertension could have adverse effects particularly in the very immature neonate.
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PMID:Plasma vasopressin, renin and catecholamines during nitroprusside-induced hypotension in the newborn lamb. 269 75

Perinatal deaths were systematically investigated over a 25-month period in a Zimbabwean district and were classified into pathological subgroups according to Wigglesworth. There were 319 perinatal deaths (a rate of 30.6 per 1000) including 83 normally formed macerated stillbirths, 28 cases of congenital malformation, 79 deaths associated with immaturity, 111 due to asphyxial conditions developing in labour and 18 specific problems. Syphilis infection was a contributory factor among 27 cases, hypertension in 39 cases, amniotic fluid infection in 31 cases and diabetes in 11 cases. An avoidable factor was detected among 242 cases (75.6%) involving the mother in 120 cases, the maternity centres in 28 and the hospital in 94. These data suggest that educational programmes should try to convince all the pregnant women to attend an antenatal clinic at least once. A further perinatal mortality reduction might be obtained through treatment for syphilis, hypertension, diabetes and amniotic fluid infection, closer monitoring of the fetal condition during labour and skillful management of dystocia.
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PMID:Perinatal mortality audit in a Zimbabwean district. 278 80

Many centrally acting drugs which are prescribed for hypertension, depression, epilepsy, insomnia and asthma may also affect fetal brain neurotransmission and behavioral states. Nearly all these drugs enter the fetal circulation following maternal administration. The immaturity of the blood-brain barrier and greater accumulation in the developing brain make the fetal brain a major target of its mother's medication. Adverse effects that are seen in the fetus are not necessarily evident in its mother. We have shown that drugs like clonidine (an antihypertensive) and clomipramine (an antidepressant), which act on noradrenaline and serotonin neurotransmission in the brain, suppress rapid eye movement sleep in the developing rat. In adulthood, the neonatally treated rats showed hyperactivity, hyperanxiety, reduced sexual behavior, disturbed sleep patterns and reduced cerebral cortical size. Furthermore, such treatment induced an increase in voluntary alcohol consumption and a decreased adaptability of responses to changes in water deprivation in a Y-maze. Little is known about long-lasting consequences of centrally acting drugs used during late gestation in humans. Minor neurological disturbances, such as delayed visual motor performance, smaller head circumference, increased anxiety and disturbed sleep-wake patterns, have been reported in children born to hypertensive mothers treated with clonidine or alpha-methyl-dopa.
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PMID:Neurochemical and electrophysiological disturbances mediate developmental behavioral alterations produced by medicines. 287 4


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