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Biomedical subjects

T Oney

Publications and source records attributed to T Oney.

At least 19 recordsLinked to original sources
PubMed1994

The extravascular contractile system in the human placenta. Morphological and immunocytochemical investigations.

In the human placenta, besides the fetal blood vessel system a second extravascular contractile system exists. It is localized in the chorionic plate and runs in a longitudinal direction and adjacent to fetal blood vessels into the stem villi, where it forms perivascular contractile sheaths. Characteristically, cells of the extravascular contractile system are extremely long and spindle-shaped and give rise to fine cell processes, by which they obviously contact each other or insert into the basement membrane of the trophoblast. They show immunoreactivity with desmin, vimentin, alpha-actin, myosin, nitric oxide synthase type I (brain form) and dipeptidyl peptidase IV. The ultrastructure suggests that cells of the extravascular contractile system are related to smooth muscle cells, including subpopulations with myofibroblastic features. In stem villi a few cells are nitric oxide synthase type I immunoreactive. These cells are thought to be specialized smooth-muscle-like cells of the extravascular contractile system or cells of the extravascular contractile system related to paraneurons that generate nitric oxide, which, in turn, may modulate the tone of perivascular contractile sheaths. The high dipeptidyl peptidase IV activity suggests that modulation of the extravascular contractile system may also occur by substance P.

Actins↗
PubMed1994

Effects of the synthetic glucocorticoid triamcinolone acetonide on vasoactive hydrolases of the human placenta in vitro.

Therapy with glucocorticoids during pregnancy is still debated. Previously reported effects of glucocorticoid application in rats resemble certain symptoms of preeclampsia. Therefore, we studied in vitro the effects of the synthetic glucocorticoid triamcinolone acetonide soluble (0.1-10 mM) on placental alpha-glutamyl amino-peptidase, microsomal alanyl aminopeptidase, dipeptidyl peptidase IV, acetylcholinesterase and butyrylcholinesterase in purified trophoblast monolayers and villous explants from first trimester (n = 5) and term placentae (n = 9) using bio- and histochemical methods. In term placentae quantitative histochemistry (microdensitometry) of trophoblast monolayers revealed an increase of alpha-glutamyl aminopeptidase and microsomal alanyl aminopeptidase activity up to 149% and 126% respectively, after treatment with supraphysiological doses. In trophoblast monolayers from first trimester alpha-glutamyl aminopeptidase activity was not affected, whereas microsomal alanyl aminopeptidase activity increased by 25%. Dipeptidyl peptidase IV staining was reduced to 26%. Biochemical measurements of alpha-glutamyl aminopeptidase and microsomal alanyl aminopeptidase activity in homogenates of cultured villi revealed effects similar to those found by microdensitometry in trophoblast monolayers. In contrast, dipeptidyl peptidase IV activity increased in explants of term placentae by 47%. Acetyl- and butyrylcholinesterase activities were reduced in term placental villi by 38% and 40%, respectively. The data indicate that glucocorticoids may affect the activity of hydrolases which are thought to be involved in local placental blood pressure modulation.

Acetylcholinesterase↗
PubMed1994

[The extravascular contractile system of the human placenta: a new aspect for function of the organ?].

In the chorionic plate and stem villi of the human placenta besides the fetal blood vessel system a second extravascular contractile system (EVCS) exists. The cells of this system contain contractile and intermediate filaments and are dipeptidyl peptidase-IV- and NO-synthase-type-I-(NOS)-immunoreactive. Therefore it can be assumed that these cells cleave the vasodilator Substance P (by DPP IV) and produce NO (by NOS) and may contribute to a modulation of the EVCS.

Amino Acid Oxidoreductases↗
PubMed1993

Enzyme histochemical evidence for the presence of potential blood pressure regulating proteases in cultured villous explants from human first trimester placentae.

The proteases dipeptidyl peptidase IV, angiotensinase A and microsomal alanyl aminopeptidase are present in the human term placenta where they may be involved in the local modulation of placental blood pressure. In order to establish an in vitro model system to study the significance of these proteases in disorders related to pregnancy-induced hypertension, the activity of the proteases was localized histochemically in cultured explants of villi from human first trimester placentae. These studies revealed a similar distribution pattern of the activity of the proteases of cryostat sections of first trimester placental villi and in cultured tissue of the same placentae. Dipeptidyl peptidase IV and angiotensinase A activity were present in cytotrophoblast cells and dipeptidyl peptidase IV activity was found in the syncytiotrophoblast, respectively. Additionally, the activity of the proteases was visualized in various populations of stromal cells. Comparing our results with former studies, the protease activity pattern in first trimester placentae was found to be the same as in term placentae. Despite morphological changes of the tissue after 14 d in culture the localization of the proteases remained unchanged up to 52 d of culture. The results suggest that placental explants may serve as a suitable in vitro model for experimental studies on the role of proteases in pregnancy-induced hypertension.

Aminopeptidases↗
PubMed1990

Variability of arterial blood pressure in normal and hypertensive pregnancy.

In normal pregnancy the circadian blood pressure rhythm is similar to that in the non-pregnant state, with the highest blood pressure values in the morning and the lowest at midnight. This rhythm is lost in patients with pre-eclampsia. Women with severe pre-eclampsia show a reversed circadian rhythm, with a nocturnal increase in blood pressure during the sleeping phase. Although the reasons for this nocturnal hypertension in severe pre-eclampsia are poorly understood, the results suggest that pre-eclamptic women are endangered by hypertensive emergencies, mostly at night. Therefore blood pressure measurement should be extended to the night, and antihypertensive treatment must be adapted to the demands of a reversed circadian rhythm in relevant subgroups of patients.

Blood Pressure↗
PubMed1989

[New aspects of anticonvulsive therapy in severe pre-eclampsia and eclampsia].

Parenterally administered magnesium is a reliable and effective treatment to prevent and control convulsions associated with preeclampsia and eclampsia. Because of several side effects in the newborn, especially in the premature child, benzodiazepines are not recommended for prolonged medication. Clomethiazole has also been used with good acceptance, but clinical experience is limited. The anticonvulsive property of magnesium is not clearly understood. Beside a well known peripheral action by neuromuscular blockade through very high serum concentrations, a central mechanism is postulated already at lower levels. The two most widely used regimens of magnesium administration are the intravenous/intramuscular (i.v./i.m.) method popularized by Pritchard and the continuous intravenous (i.v.) route recommended by Zuspan. The concentrations of magnesium in the serum achieved with the i.v./i.m. regimen are significantly higher than those produced by the i.v. administration, especially in the first three hours after initiation of the treatment and if a maintenance dose of 1 g/h is chosen. Although therapeutic concentrations of magnesium effective to prevent seizures have been reported between 1.3 and 4.0 mmol/l, repeated convulsions are occasionally seen during i.v. regimen and at concentrations below 2 mmol/l. Because of this observation, a maintenance dose of 2 g/h and in some cases 3 g/h is required during the first hours of treatment. Side effects in mother and newborn are low, if there is no renal impairment and the treatment instructions are strictly followed. Respiration as well as urinary output have to be monitored at periodic intervals and the patellar reflex should be present. Calcium gluconate, 10 ml of a 10% solution, is an effective antidote in case of magnesium intoxication.

Anticonvulsants↗
PubMed1988

Relationship between serum prolactin concentration, vascular angiotensin sensitivity and arterial blood pressure during third trimester pregnancy.

Prolactin may play an important role in the pathogenesis of pregnancy-induced hypertension (PIH) and preeclampsia. In 105 normotensive nulliparous women at 28 to 32 weeks of gestation, the relationship between serum prolactin concentration (PRL) and blood pressure behaviour was examined under standardized conditions. Neither postural change from left lateral to supine recumbency nor the infusion of low doses of angiotensin-II-amide had an effect on PRL levels. Similar mean PRL levels were found in pregnant women with a low angiotensin pressor dose (ADP less than 10 ng x kg-1 x min-1) or "angiotensin sensitivity", a positive supine pressor response (delta pd greater than or equal to 20 mmHg) or an increased serum uric acid concentration (greater than 3.6 mg/dl), which are criteria for an increased risk of developing hypertensive complications. However, in the group of subjects with angiotensin sensitivity, a significant correlation was found (a) between PRL levels and the APD and (b) between PRL levels and diastolic blood pressure increase after 5 min of supine recumbency. These results may reflect diminished dopaminergic activity in the central nervous system, which could influence both blood pressure and prolactin secretion.

Adolescent↗
PubMed1985

[Effect of oxytocin on renin activity and aldosterone concentration in plasma as well as blood pressure in late pregnancy and early puerperium].

The effects of a low-dose oxytocin infusion on blood pressure during late pregnancy and early puerperium are unclear, and its effects on the renin-aldosterone axis are unknown. The present investigation was performed in 24 pregnant subjects at term and in 14 women within five days after vaginal delivery, 10 and 7 of these subjects serving as controls (5% laevulose being infused without oxytocin). A slight but significant decrease of plasma renin activity was found during oxytocin infusion antepartum as well as postpartum. The decrease of aldosterone concentration in plasma was also significant during late pregnancy, but not during the puerperium. An increase of diastolic blood pressure was only observed antepartum. In summary, however, the changes of blood pressure, renin and aldosterone described in the perinatal period in normotensive subjects were small and without clinical importance.

Adolescent↗
PubMed1983

The value of the mean arterial blood pressure in the second trimester (MAP-2 value) as a predictor of pregnancy-induced hypertension and preeclampsia. A preliminary report.

In 200 healthy nulliparous women the mean arterial blood pressure in the second trimester (MAP-2 value) was calculated. 85 women (42 %) had a MAP-2 value of greater than or equal to 90 mmHg (positive test result), but only 27 women (32 %) developed a hypertensive complication. Conversely, 113 of the 115 (98 %) women with a negative test result (MAP-2 value less than 90 mmHg) remained normotensive. Only two women of this group (2 %) later showed a mild pregnancy-induced hypertension. Thus, the MAP-2 value has a high sensitivity (93 %) and a high predictive value of negative test results (98 %). On the other hand, there is a high rate of false-positive results (68 %) and thus a low predictive value of positive test results (32 %). It is concluded that the MAP-2 value is a simple method for selecting pregnant women who should be examined with other more specific predictive tests. Alternatively, weekly measurements of blood pressure are recommended for early diagnosis of hypertensive disorders of late pregnancy in all women with a MAP-2 value of 90 mmHg or more.

Blood Pressure Determination↗
PubMed1982

[Significance of blood pressure and body weight in the early diagnosis of gestosis. Preliminary report].

Mean weight gain is higher in gestosis than in normal pregnancy. On the other hand, many patients with gestosis had an insignificant increase in body weight. Therefore, the weight gain in pregnancy does not have a predictive value concerning the later risk of developing gestosis. The supine pressor test ("roll-over test") and the determination of mean arterial pressure during weeks 18 to 26 of gestation (MAP-II-value) are simple and appropriate methods for early diagnosis of gestosis. By using the supine pressor test or by determination of the MAP-II-value, 73% or over 90%, respectively, of all subjects with later gestosis could be recognized before the onset of first clinical symptoms of the disease (n = 108). As both methods frequently show false-positive results, a high percentage of pregnant women needs intensive care during the last trimester. In order to select further women with increased risk of gestosis, it is proposed to calculate the MAP-II-value first and to determine the supine pressor response at least in those primigravidae with a MAP-II-value of 90 mmHg or more.

Blood Pressure↗
PubMed1982

The value of the angiotensin sensitivity test in the early diagnosis of hypertensive disorders in pregnancy.

Normal pregnant women are resistant to the pressor effect of intravenously administered angiotensin II (AII), but women who are destined to develop hypertensive complications in pregnancy show an increased sensitivity to AII several weeks before the onset of the first clinical symptoms. In 231 normotensive nulliparous women (age 25 +/- 5 years), an angiotensin sensitivity test (AST) was performed between weeks 28 and 32 of gestation. If an effective angiotensin pressor dose (APD) of less than 10 ng . kg-1 . min-1, is considered to be a positive test result, 58 subjects had a positive AST and 173 had a negative AST. Twenty-six of 34 women who ultimately developed pregnancy-induced hypertension (PIH) or preeclampsia had a positive test, and the diagnosis was made early. Each of the eight pregnant subjects with a false negative test developed only a mild form of the hypertensive disorder. In this series, 11 women had a premature onset of labor; eight of them also had an APD of less than 10 ng . kg-1 . min-1. The study confirms the high predictive value of negative test results. Therefore, the AST can be used as an appropriate method for identifying women who are destined to develop hypertensive complications in pregnancy. However, because of the low practicability of the test, it may not be recommended as a screening method in routine prenatal care.

Adolescent↗
PubMed1982

Effect of sodium chloride and sorbitol infusions on vascular angiotensin reactivity during third trimester pregnancy.

Normal pregnancy is associated with refractoriness to the pressor effects of i.v. administered angiotensin II (A II). In pre-eclampsia, this refractoriness to A II is lost several weeks prior to the increase of blood pressure. Infusions of 200 ml of 3% saline or of 40% sorbitol over 30 min, or administration of 2,000 ml of normal saline infused over 2 h, respectively, resulted in an increased vascular angiotensin sensitivity. The effective angiotensin pressor dose (APD) decreased significantly after each test substance (decrease of the mean APD 14.5% after 3% saline, 24% after 40% sorbitol and 25% after normal saline). The data confirm the hypothesis that the principal determinant of pressor responsiveness to A II during pregnancy is arteriolar response; this seems to be modulated by alterations in the sodium content of the vessel wall.

Adolescent↗
PubMed1982

Effect of angiotensin infusion during pregnancy on fetal heart rate and on fetal activity.

The angiotensin sensitivity test is of value in predicting patients at increased risk of pregnancy-induced hypertension and preeclampsia. Studies on the effects of angiotensin II on uterine blood flow in various species showed contradicting results. In the present study, 15 pregnant women were monitored by cardiotocography before, during and after an infusion of angiotensin II-amide (maximal infusion rates 6.3--23.2 ng . kg-1. min-1). No remarkable changes in fetal heart rate, oscillatory frequency and amplitude, as well as in the number of accelerations and fetal movements could be observed. It may be concluded from these results that the fetal condition is not compromised by an angiotensin sensitivity test.

Adult↗
PubMed1982

[Amniotic fluid embolism with coagulation disorder--a case report (author's transl)].

A case of amniotic fluid embolism during the delivery of a twin pregnancy is reported. After immediate resuscitation with artificial ventilation the mother and the neonates survived the acute episode. As a result of hyperfibrinolysis with premature separation of the placenta a dramatic postpartum haemorrhage occurred, which could be controlled by Fritsch' manoeuvre. Meanwhile it was possible to restore the coagulation disorder with fresh whole blood, fibrinogen and an antifibrinolytic agent (Aprotinin).

Aprotinin↗
PubMed1982

Inhibition of the renin--aldosterone axis and of prolactin secretion during pregnancy by L-dopa.

Recently, interactions between dopaminergic mechanisms and aldosterone secretion were described in non-pregnant subjects. The present study examined the effect of 1000 mg of L-dopa by mouth on plasma renin activity (PRA), and the concentrations of plasma aldosterone (PA) and prolactin (PRL) during normal pregnancy. Under basal conditions, there was a clear decrease of PRA, PA and PRL 60 min after oral intake of L-dopa in seven subjects; a further decrease was observed during the following 45 min, resulting in a total decrease of 41 (PRA), 44 (PA) and 56 (PRL) % of the respective arithmetic mean of the basal values. However, the response of PA to isopressor angiotensin II infusions was comparable before and shortly after treatment with L-dopa in 16 pregnant subjects. The decreased activity of the renin-aldosterone axis after administration of L-dopa may be attributed to an accumulation of dopamine and catecholamines in the brain, resulting in a diminution of sympathetic outflow from the central nervous system. The simultaneous and comparable changes of both PRA and PA after L-dopa treatment, as well as the reversibility of aldosterone suppression by infusion of angiotensin II, suggest that the inhibition of aldosterone secretion by L-dopa is mediated by a decrease of renin release.

Aldosterone↗
PubMed1982

[The value of a single determination of serum uric acid concentration in the early diagnosis of hypertensive disorders in pregnancy (author's transl)].

In 200 healthy, normotensive nulliparous women, a single determination of serum uric acid concentration was done between weeks 28-32 of gestation in order to identify a possible increased risk of developing hypertensive complications. If serum concentrations higher than 3.6 mg/dl were considered as increased ("positive test"), women who developed toxaemia of late pregnancy (proteinuric hypertension), had a significantly elevated mean serum uric acid concentration already at the beginning of the third trimester (p less than 0.01). The incidence of toxaemia and hypertensive disease without proteinuria was significantly higher in the group of women with an elevated uric acid value (p less than 0.001). Only 9% of pregnant women with a "negative test" ultimately developed a mild form of a hypertensive complication. Conversely, 74% of the patients with a "positive test" remained normotensive. Thus, the predictive value of a "positive test" is low (26%) and that of a "negative test" relatively high (91%).

Adolescent↗