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Biomedical subjects

E M Symonds

Publications and source records attributed to E M Symonds.

At least 163 records · Page 9Linked to original sources
PubMed1977

Plasma renin and aldosterone in pregnancy complicated by adrenal insufficiency.

Serial measurements of plasma renin and plasma aldosterone were made throughout pregnancy in two women with adrenal insufficiency. The values were compared with levels obtained in eight normal primigravidae. Aldosterone levels were low or undetectable in adrenal insufficiency and plasma renin levels were grossly elevated in one patient with adrenal insufficiency but within the normal range in the other.

Adrenal Insufficiency↗
PubMed1976

The effect of parturition on amniotic fluid lecithin concentration.

Amniotic fluid lecithin has been measured during the antenatal period and at comparable periods of gestation at the onset of spontaneous labour. Lecithin values were higher in labour, the difference being statistically significant in two of the three groups studied. Lecithin values were also measured serially during induced labour in 14 normal women at term. A significant fall was observed throughout labour. Creatinine levels were measured in the amniotic fluid in five of these patients and showed no significant change.

Amniocentesis↗
PubMed1976

Scanning electron microscope appearances of normal human amnion and umbilical cord at term.

The surface morphology of normal term amnion was studied by scanning electron microscopy. Four patterns were observed. Two of the patterns showed distinctive minority populations of cells. In one, there were cells surrounded by intracellular channels; in the other, there were large flat cells. The microvilli in all four patterns showed variable morphology in different samples. Possible functional implications of the findings are discussed.

Amnion↗
PubMed1976

The renin-angiotensin system and sodium excretion during gestation.

The renin-angiotensin system shows a marked increase in activity in normal pregnancy, with the major changes occurring in the first trimester. Evidence is presented to show that there is a physiologically inactive prorenin present in the plasma during pregnancy that achieves highest levels in the first half of pregnancy. The significance of this "acid-activated" renin has yet to be determined. Plasma angiotensin II levels are elevated throughout normal pregnancy, and a significant positive relationship has been established between maternal venous and cord venous levels at delivery. Recent studies on plasma AII levels in pregnancy hypertension have shown a positive correlation between diastolic blood pressure and plasma AII, and there is evidence that the high circulating levels of angiotensin may result in a feed-back suppression of renal renin release. Studies on the fetal circulation at delivery have also shown high levels of AII in the cord venous blood of infants born to mothers with pregnancy hypertension. Despite the increased level of activity of the renin-angiotensin system in normal pregnancy, sodium homeostasis is maintained. The possible reasons for the increased activity are discussed briefly.

Angiotensin II↗
PubMed1976

The fetal renin-angiotensin system in normal and hypertensive pregnancy.

Plasma angiotensin II was measured in the umbilical cord arterial and/or venous blood of 54 babies delivered vaginally and in 12 delivered by elective lower segment cesarean section. Angiotensin II was also measured in the peripheral venous blood of 51 of the mothers. Mean angiotensin II levels at delivery were higher in the cord venous blood of infants born to hypertensive than to normotensive mothers. Cord venous angiotensin II levels were always higher than those of the mother and there was a strongly positive relationship between maternal and fetal angiotensin II. The duration of the second stage of labor was found significantly to affect fetal angiotensin II levels, prolonged labor being associated with high levels. When this was taken into account, there was a highly significant positive relationship between the body weight of the infants and cord venous angiotensin II levels. There was an inverse relationship between cord venous pH and angiotensin II levels. Babies delivered by lower segment cesarean section had much lower angiotensin II levels than those delivered vaginally. The levels were, however, twice as high as those in the nonpregnant adult.

Angiotensin II↗
PubMed1976

Changes in the renin-angiotensin system in normotensive and hypertensive women during pregnancy and parturition.

Plasma renin activity, plasma renin concentration and plasma angiotensin II were measured in 18 primigravid women and 17 multiparous women between 37 and 42 weeks of gestation. Seven of the primigravid and seven of the multiparous women were admitted to hospital because they developed hypertension during pregnancy. In the primigravid group, the mean angiotensin II level was significantly higher in the hypertensive than in the normotensive women. A highly significant correlation was found between diastolic blood pressure and plasma angiotensin II levels. Although a similar trend was seen in the multiparous women, there was a wide scatter of values and the relationship between diastolic blood pressure and plasma angiotensin II was not significant. No correlation could be established between plasma renin concentration and angiotensin II levels. However, there was a trend towards a negative correlation between plasma renin activity and plasma angiotensin II, suggesting that high angiotensin levels may suppress renal renin release. The influence of parturition on plasma angiotensin II levels was investigated in 12 women. Maternal plasma angiotensin II levels were significantly higher in the second stage of labor than in women delivered by elective cesarean section.

Angiotensin II↗
PubMed1975

Changes in the renin-angiotensin system in primigravidae with hypertensive disease of pregnancy.

Plasma renin concentration, renin activity and angiotensin II (AII) have been studied in 35 primigravidae at or near term immediately prior to surgical induction of labour. A highly significant positive correlation was established between diastolic blood pressure at the time of sample collection and plasma AII. This relationship was observed over the range of diastolic pressure studied irrespective of the diagnosis made at the time of admission to hospital. In patients with hypertension, a significant negative relationship was established between plasma renin concentration and renin activity and AII. Furthermore, plasma AII levels were higher for a given plasma renin activity or plasma renin concentration in the hypertensive women than in the normotensive group. These findings suggest that the renin-angiotensin system is actively involved in hypertensive disease of pregnancy and that suppressed levels of renin concentration and activity may result from elevated angiotensin levels. It is suggested that the utero-placental complex may be the source of the elevated AII levels.

Adolescent↗