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Biomedical subjects

S Niesert

Publications and source records attributed to S Niesert.

At least 37 records · Page 2Linked to original sources
PubMed1989

Inactivation of prostaglandins in human decidua vera (parietalis) tissue: substrate specificity of prostaglandin dehydrogenase.

Prostaglandin dehydrogenase catalyzes the initial reaction in the inactivation of prostaglandin E2 and F2 alpha. To address the potential importance of this enzyme in regulating the tissue levels of active prostaglandins, we evaluated the kinetic properties of prostaglandin dehydrogenase in uterine decidua vera tissue of women. Specifically, we characterized the enzyme activity under optimal in vitro conditions in cytosolic fractions of uterine decidua vera tissue obtained at term and compared the substrate and cosubstrate specificities of prostaglandin dehydrogenase in cytosolic fractions of decidual tissues. The incubation conditions were optimized with either prostaglandin E2 or F2 alpha and nicotinamide-adenine dinucleotide or nicotinamide-adenine dinucleotide phosphate as substrates to ensure linearity of product formation with time of incubation and protein concentration. The apparent Michaelis-Menten constant of nicotinamide-adenine dinucleotide-dependent prostaglandin dehydrogenase for prostaglandin E2 was 5.5 mumol/L. The apparent Michaelis-Menten constant of nicotinamide-adenine dinucleotide phosphate-dependent prostaglandin dehydrogenase for prostaglandin F2 alpha was 15 mumol/L. Prostaglandin E2 serves as a better substrate for prostaglandin dehydrogenase than does prostaglandin F2 alpha, irrespective of the cosubstrate. In cytosolic fractions of decidual tissues, the specific activity (apparent Vmax) of nicotinamide-adenine dinucleotide-dependent prostaglandin dehydrogenase was greater than that of nicotinamide-adenine dinucleotide phosphate-dependent prostaglandin dehydrogenase. In addition, we found that in decidual tissue obtained before or after the onset of labor, the specific activity of prostaglandin dehydrogenase varied widely. In tissues obtained after delivery by cesarean section, no significant differences were apparent in the specific activity of the enzyme before (9.3 to 125.8 nmol/min/mg protein) and after (27.8 to 103.4 nmol/min/mg protein) the onset of labor. In cytosolic fractions of decidual tissue obtained after vaginal delivery, the specific activity of nicotinamide-adenine dinucleotide-dependent prostaglandin dehydrogenase ranged from undetectable levels to 38.4 nmol/min/mg protein. We speculate that nicotinamide-adenine dinucleotide-dependent prostaglandin dehydrogenase in decidua serves to regulate the levels of bioactive prostaglandins in decidua vera tissue and the amounts of prostaglandins (and metabolites) produced in decidua or fetal membranes that reach myometrium and fetal membranes and enter maternal blood and amniotic fluid.

Cesarean Section↗
PubMed1989

[Pregnancies following kidney transplantation and in immunosuppression with cyclosporin A].

From 1984 to 1987, offspring from six renal transplant-patients were delivered in the Department of Obstetrics and Gynaecology of the Medical School of Hannover. The patients received cyclosporine and cortisone as an immunosuppressive therapy during the pregnancies. All pregnancies ended with live births; in two cases, a caesarean section was performed. Serious congenital malformations of the newborns were not observed, only two newborns being small. In the blood of the newborns, the cyclosporine concentrations were between 85 and 65% of the maternal blood levels. In two patients, the kidney functions deteriorated significantly during and after pregnancy. An increase in blood pressure or a hypertonic crisis, however, did not occur.

Adult↗
PubMed1989

[Detection of cyclosporin A in breast milk--is breast feeding contraindicated?].

Cyclosporin A (CyA) was measured simultaneous in breast milk and maternal and fetal blood with a new monoclonal specific radioimmunoassay in a patient who was treated with Cyclosporin A during pregnancy because of kidney transplantation. CyA-levels in breast milk were 15 to 90% higher than in maternal blood. In case of breast feeding a child would take up less than 5 percent of an immunosuppressive dose. However, we would recommend ablactation because of the toxicity and the unknown side effects of CyA for the child's immunologic system.

Adult↗
PubMed1988

[Disorders of liver function, thrombopenia and hemolysis in a special clinical form of hypertension in pregnancy (the so-called HELLP syndrome)].

The so called HELLP syndrome is a severe complication of pregnancy-induced hypertension, characterized by haemolysis (H), elevated liver enzymes (EL) and low platelet counts (LP). The data of 37 patients with a HELLP syndrome are presented. In addition to the clinical symptoms of pregnancy-induced hypertension, 21 patients suffered from abdominal pain and 5 patients from icterus. Thrombocytopenia, haemolysis and elevated liver enzymes were observed in every case. In 28 of the patients a Caesarean section was performed to prevent further deterioration of the disease. Three patients died post partum as a consequence of severe complications. In five pregnancies intrauterine deaths were observed. The results of this retrospective study confirm the great risk for both the mother and the foetus, if pregnancy-induced hypertension is complicated by a so called HELLP syndrome.

Adult↗
PubMed1987

[Risks of cesarean hysterectomy].

From 1976 through 1984, 48 primary caesarean hysterectomies were performed in the Department of Obstetrics and Gynaecology of the Medical School of Hannover. The indications for the operation, the risk factors and the postoperative course were analysed and compared with a control group of patients with a Caesarean section. Caesarean hysterectomies had a higher incidence of excessive blood loss, blood transfusion and urinary tract injury, especially of the bladder. Based on this experience Caesarean hysterectomy should be performed if a valid indication is present. The operation cannot be recommended routinely for the purpose of sterilisation.

Adult↗
PubMed1987

[Amniocentesis in the 2d trimenon: comparison of 2 technics].

The results of 1245 amniocenteses performed by the "free hand needle" technique and ultrasonic control are discussed. The use of ultrasonic control showed a much lower incidence of blood-stained amnionic fluid as well as a decreased number of repeated punctures of the amnion. The abortion rate was almost the same in both groups. According to our experience ultrasonic controlled puncture seems to be more reliable in terms of safety and success.

Abortion, Spontaneous↗
PubMed1987

[Stomach cancer and pregnancy].

The symptoms of gastric carcinoma are nonspecific and uncharacteristic especially during the pregnancy. Two cases of gastric carcinoma in pregnancy are reported. In both cases the diagnosis of the malignoma was not made in an early stage. Therefore both women died within a short period after the delivery due to the metastasis of the gastric cancer. The newborns survived the complicated pregnancy and they were born spontaneously and by cesarean section. The reasons for the delayed diagnosis and the problems of this malignoma during a pregnancy are discussed based on the own observations and the published cases.

Adenocarcinoma↗
PubMed1986

The effect of fetal urine on arachidonic acid metabolism in human amnion cells in monolayer culture.

Human amnion cells in primary monolayer culture were used as a model system to evaluate the regulation of arachidonic acid metabolism and prostaglandin E2 production in amnion. Amnion cells were incubated with carbon 14-labeled arachidonic acid, and after various times the distribution of radiolabeled arachidonic acid in the lipids of these cells were determined. After incubation for 72 hours, 91% of the total radiolabeled arachidonic acid incorporated into cellular lipids was present in glycerophospholipids, and 9% was present in neutral lipids. The formation of [14C]prostaglandin E2 from [14C]arachidonic acid was maximal after 8 hours. In these studies the effect of human fetal urine on arachidonic acid metabolism in these cells was investigated (the production of prostaglandin E2 by amnion cells is increased by treatment with fetal urine). In cells incubated with [14C]arachidonic acid in the incubation medium, treatment with fetal urine for 4 hours caused a threefold to fourfold increase in [14C]prostaglandin E2 production, yet there were no detectable differences in the content of [14C]arachidonic acid in specific glycerophospholipids or neutral lipids of the cells after such treatment. In other studies, amnion cells were preincubated for 72 hours with [14C]arachidonic acid, and thereafter the cells were treated with fetal urine for 24 hours. With fetal urine treatment the amount of [14C]arachidonic acid in triacylglycerols decreased significantly compared with that in nontreated cells, but the formation of [14C]prostaglandin E2 was not increased. Thus we suggest that in response to fetal urine, prostaglandin E2 is formed from arachidonic acid that is released from a highly specific, stimulus-sensitive lipid pool or else from arachidonic acid that is derived from extracellular sources.

Amnion↗
PubMed1986

Prostaglandin E2 9-ketoreductase activity in human decidua vera tissue.

Amnion is believed to be a tissue of central importance in the biochemical processes of parturition. In this tissue, prostaglandin E2 is the near exclusive prostaglandin produced. And although the production of prostaglandin E2 is increased during labor in women, the levels of the major metabolite of prostaglandin E2 in maternal plasma are not elevated; rather, the levels of 13,14-dihydro-15-ketoprostaglandin F2 alpha, the major circulating metabolite of prostaglandin F2 alpha, are increased strikingly. Because of this apparent paradox, we considered the possibility that prostaglandin E2, originating in amnion, chorion laeve, or decidua vera, is converted to prostaglandin F2 alpha in decidua vera by the action of prostaglandin E2-9-ketoreductase. We found that prostaglandin E2 9-ketoreductase, the enzyme that catalyzes the conversion of prostaglandin E2 to F2 alpha, is present in cytosolic fractions prepared from homogenates of uterine decidua vera tissue. The specific activity of 9-ketoreductase in cytosolic fractions of decidua of six women varied from 3.2 to 155 pmol X min-1 X mg-1 protein. We also evaluated the conversion of exogenous prostaglandin E2 to F2 alpha in intact human endometrial stromal cells in monolayer culture. We found that prostaglandin E2, added to the culture medium, was converted to prostaglandin F2 alpha by endometrial stromal cells that were maintained in the presence of inhibitors of prostaglandin synthase. The extent of conversion of exogenous prostaglandin E2 to F2 alpha, however, was low relative to the specific activity of prostaglandin E2 9-ketoreductase found in decidual cytosol. These findings are consistent with the possibility that prostaglandin E2 formed in decidua vera tissue may be converted in that tissue to prostaglandin F2 alpha by 9-ketoreductase; on the other hand, prostaglandin E2 formed in contiguous tissues probably is not converted significantly to prostaglandin F2 alpha by decidual 9-ketoreductase.

Cytosol↗
PubMed1986

[Neurofibromatosis and pregnancy].

A case of neurofibromatosis (Recklinghausen's disease) in pregnancy in a 29-year-old patient is reported. The woman has had two uncomplicated pregnancies and deliveries. The lesions of the neurofibromatosis did not change during the course of the pregnancy. However, based on the few published cases it is necessary to pay attention to hypertension or an exacerbation of the neurofibromatosis.

Adult↗
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↗
PubMed1984

[Cushing syndrome and pregnancy].

Pregnancies in cases of Cushing syndrome are rare. When conception occurs the complication rate is high especially from hypertension and superimposed toxemia. Abortions, premature deliveries, and stillbirth occur more often. In the case described an adenoma of the adrenal gland was diagnosed early in pregnancy. Frequent prenatal care and treatment of the hypertension resulted in a pregnancy of 34 weeks gestation. At this time low HPL and estriol values and variable decelerations forced a Cesarean section. The premature infant was discharged in good condition after several weeks of cortico-steroid substitution. In the mother a well defined adrenal cortical tumour at right was found post-partum. The operative specimen showed an adenomatous nodular adrenal cortical hyperplasia. The described case shows that frequent prenatal care and early hospitalization permit an expectant treatment of pregnancy in cases of Cushing-Syndrome.

Adenoma↗
PubMed1981

[Oral steroid contraception in hyperprolactinemia (author's transl)].

A study on the statistical correlation between oral contraceptives and similar mixtures of steroids and the development and maintenance of hyperprolactinemia is presented. 91 cases with hyperprolactinemia-amenorrhoea were compared to a group of 91 women with amenorrhoea and normal prolactinemia. Matched pairs regarding duration of amenorrhoea, parity, gonadal function and thyroid function were used. It was shown that oral contraceptives and similar combination of estrogen and progesterone do not increase the relative risk for functional or adenomatous hyperprolactinemia. There were no evidence that existing adenomas were deteriorating during oral contraception. However, two cases with pituitary adenoma following long-term high dosage estrogen therapy was found. The presented results show that low dosage steroid medications do not increase the risk for the development or maintenance of hyperprolactinemia.

Adenoma↗