Biomedical subjects
K Korte
Publications and source records attributed to K Korte.
Purification of prostaglandin E2-9-oxoreductase from human decidua vera.
Prostaglandin E2-9- oxoreductase (PGE2-9-OR), the enzyme which converts prostaglandin E2 (PGE2) to prostaglandin F2 alpha (PGF2 alpha), has been detected in human decidua vera. A 105-fold purification was achieved when the centrifuged homogenate was fractionated sequentially by DEAE-Trisacryl, hydroxyapatite-agarose gel, ultrogel AcA 44 and Matrex gel blue A gel chromatographies. The following kinetic constants for PGE2-9-OR have been obtained. The equilibrium constant with respect to PGE2 is 83 microM, the Michaelis constant, Km, for PGE2 is 80 microM, for NADPH 1.6 microM. The maximal velocity for the forward reaction is V1 = .203 pmol/min. The enzyme was inhibited by progesterone, oestradiol-17 beta, cortisol and pharmaceutical drugs. An activating effect could be demonstrated with Ca2+ and oxytocin. The occurrence of PGE2-9-OR in the decidua vera suggests that this enzyme may be responsible for the transformation of PGE2 to PGF2 alpha in these tissues. This may be an important mechanism for the initiation and maintenance of uterine contractions.
Metabolism of arachidonic acid and prostanoids in human endometrial stromal cells in monolayer culture.
In the present investigation, we compared the metabolism of arachidonic acid in human endometrial stromal cells maintained in monolayer culture with that in human decidual tissues. By gas-chromatographic analysis, the distribution of arachidonic acid in glycerophospholipids and in the neutral lipids of decidual tissues and stromal cells in culture was similar. After the addition of [14C]arachidonic acid to the culture medium, steady-state conditions with respect to radioactive labeling of the lipids of the cells were attained after 24 h, except for phosphatidylethanolamine and neutral lipids. The percentage distribution of [14C]arachidonic acid in the lipids of the cells in culture was as follows: phosphatidylcholine, 41%; phosphatidylserine, 5%; phosphatidylinositol, 19%; phosphatidylethanolamine, 22%; neutral lipids, 11%. This distribution of arachidonic acid among the lipids is similar to that in decidual tissue, except for that in phosphatidylethanolamine. The amount of radioactivity in phosphatidylethanolamine continued to increase up to 72 h whereas that in neutral lipids declined after a maximum amount was present at 4 h. In the cells in monolayer culture, [14C]prostaglandin E2 and [14C]prostaglandin F2 alpha were produced from [14C]arachidonic acid, as is true in superfused decidual tissue. The similarities in arachidonic acid metabolism in these cells to that in decidual tissue are supportive of the proposition that endometrial stromal cells in monolayer culture are an appropriate model for the study of the regulation of arachidonic acid release and prostaglandin formation by endometrium and decidua vera.
Steroidogenesis in dispersed cells of human fetal adrenal.
Steroidogenesis in dispersed fetal zone cells of midtrimester human fetal adrenal was stimulated acutely by ACTH. Polypeptide hormones such as hCG, alpha MSH, ovine PRL, and LH did not produce a similar stimulation of steroidogenesis. The principal steroid products of ACTH-stimulated fetal adrenal cells were dehydroisoandrosterone sulfate, pregnenolone, pregnenolone sulfate, and 17 alpha-hydroxypregnenolone. Only minimal production of the delta 4-3-ketosteroids, cortisol, corticosterone, and progesterone, was observed. Cyanoketone (2 alpha-cyano-4,4,17 alpha-trimethyl-17 beta-hydroxyandrost-5-en-3-one; an inhibitor of 3 beta-hydroxysteroid dehydrogenase activity) treatment of the cells caused only a minor increase in 3 beta-hydroxysteroid formation, confirming that 3 beta-hydroxysteroid formation is the principal steroidogenic fate of cholesterol in these cells. SU-10603 [7-chloro-3,4-dihydro-2-(3-pyridyl)naphthalen-1-(2H)one; a steroid 17 alpha-hydroxylase inhibitor] treatment of the cells caused a marked accumulation of pregnenolone sulfate, indicating that the C-19 steroids are produced from C-21 steroids in this tissue and possibly that dehydroisoandrosterone sulfate is synthesized directly from pregnenolone sulfate. ACTH-stimulated pregnenolone synthesis was inhibited by AY-9944 [trans-1,4-bis-(2-chlorobenzylaminomethyl) cyclohexane dihydrochloride; an inhibitor of cholesterol biosynthesis]. Thus, cholesterol synthesized de novo was the likely steroidogenic precursor in the acute hormonally stimulated fetal adrenal cells.
Phospholipid and neutral lipid separation by one-dimensional thin-layer chromatography.
A simple and rapid method for separation of six major phospholipids and four major neutral lipids from cell extracts by one-dimensional preadsorbent thin-layer chromatography was developed. Due to the inert characteristics of the preadsorbent layer (Celite) no separation occurs until the sample reaches the preadsorbent (Celite)-silica gel junction. The compounds were applied to the preadsorbent (Celite) area (625 mm2) in 10-microliters aliquots (total volume of 0.15 ml). By this method, samples can be applied rapidly in large volumes without respotting any area of the preadsorbent layer. The time required to apply one sample was reduced considerably (2 min) compared to conventional methods (10 min). Since all the compounds move with the solvent front as a sharp, narrow band to the preadsorbent (Celite)-silica gel boundary, excellent separation was achieved when up to 650 micrograms of lipid material was applied on each lane (25 mm wide). Thus, this method is suitable for the separation of relatively large amounts of radiolabeled and non-radiolabeled lipids and free fatty acids from extracts of biological fluids, tissues, or cells maintained in monolayer culture.
Sterol sulfate metabolism in the adrenals of the human fetus, anencephalic newborn, and adult.
The sulfurylation of pregnenolone (delta 5P), dehydroepiandrosterone (D) and cholesterol in subcellular fractions of the separated zones of normal human fetal adrenals as well as the mitochondrial sterol desmolase activities are investigated. The values obtained are compared to those found in adrenal tissues of anencephalics and adults. The 3 beta-hydroxysteroid sulfotransferase activity is localized principally in the cytosolic fraction of the tissues assayed. The highest rate of sulfurylation of delta 5P and D is found in the cytosol of the fetal zone (5 nmol min-1 mg protein-1). The corresponding activities in fetal neocortex, anencephalic, and adult adrenocortical tissues are one tenth of that in the fetal zone. Cholesterol sulfurylation is not detectable under similar assay conditions. The specific activities of cholesterol and cholesteryl sulfate desmolases are 3- 4-fold greater in the fetal zone than in the neocortex. Cholesterol desmolase activity, but not cholesteryl sulfate desmolase activity, is found in adrenal tissues of the anencephalic newborn and adult adrenal cortex. It is concluded that the high levels of delta 5P sulfate and D sulfate found in human fetal plasma arise not only as a consequence of the high capacity of the human fetal adrenal fetal zone to sulfurylate the unconjugated compounds, but also as a result of the conversion of cholesteryl sulfate to delta 5P sulfate and thence to D sulfate.
[The serum levels of estradiol-17 beta and progesterone following hyper-stimulation of the ovaries by clomiphen].
The serum levels of estradiol-17 beta and progesterone in a cycle which was hyperstimulated by Clomiphen are reported. The pre-ovulatory maximum of estradiol-17-beta was 3,240 pg/ml, the maximum during the luteal phase was 2,930 pg/ml. The increase of progesterone to 54.8 ng/ml during the luteal phase was an indication of multiple ovulation. Bilateral ovarian enlargement was palpated. At the same dosage in the following menstrual cycle the maximum pre-ovulatory estradiol-17-beta was 962 pg/ml and the maximum progesterone in the luteal phase was 9.1 ng/ml. During this second cycle the ovaries were not palpably enlarged. It is concluded that sensitivity of the ovaries to hyper-stimulation by Clomiphen may vary from menstrual cycle to menstrual cycle. A single hyperstimulation does not necessarily indicate further hyperstimulation in subsequent cycles.
alpha-Fetoprotein, carcinoembryonic antigen, human chorionic gonadotropin and its beta subunit in metastatic choriocarcinoma: short-term follow-up and determinations of resistance during chemotherapy.
Serum levels of alpha fetoprotein (AFP), carcinoembryonic antigen (CEA), human chorionic gonadotropin (hCG) and its beta subunit (beta-hCG) were measured during the therapy of a choriocarcinoma with lung metastases. All AFP determinations were in the normal range. The CEA levels showed a correlation with the radiologically confirmed development of lung metastases. A rise of hCG during the first 2--6 days to 177.3--407.5% of the initial level and a descent to 17.9--33.7% of the initial level at the 10th day of therapy were typical behavioral patterns associated with tumor sensitivity. The onset of tumor resistance against the chemotherapeutic preparation used was evident within 10 days after therapy. A small rise, a slight fall below the initial value, and then a rapid increase to above the initial level were typical parameters. With established tumor resistance there was an autonomous unremitting increase of hCG activity. Short-term follow-up to hCG in intervals of 2 days at least for over a period of 10 days are deemed advisable for early detection of resistance toward the particular chemotherapeutic preparation used.
[Problems of dextran-charcoal-separation of free from antibody-bound steroid in a direct radioimmunoassay of progesterone without chromatography and extraction (author's transl)].
A method for radioimmunoassay of serum progesterone is described which does not require extraction. A chromatographic step is not necessary because of the high specifity of the antibody. The intrassay coefficient of variation was 6.1% and the interassay coefficient of variation was 8.4%. The detection limit was 10 pg/tube that means 1 ng/ml serum. The test on parallelity was correct up to 10 microliter serum. The results compared with results of a radioimmunoassay with extraction were identical. High concentrations of hormone in serum and an antibody of high specifity are required for the direct radioimmunoassay of steroids. Using the dextran-charcoal system for separation of free from antibody-bound steroid the relationship of the quantity of serum to the quantity of charcoal is of great importance. These problems are discussed.
[Serumprolactin and lactation in a case of placental sulfatase deficiency].
In a pregnancy with placental sulfatase deficiency very low serum concentrations of estrone and estradiol-1 7 beta are found. Estriol is not detectable. In spite of this serum concentrations of prolactin were in the normal pregnancy range. There was no premature lactation in pregnancy. Lactation in puerperium was unsatisfactory.
[Diagnosis of placental sulphatase deficiency (author's transl)].
In a 23-year old primipara who was in her 34th week of pregnancy, serum oestriol could not be identified, with no other abnormal clinical and endocrinological findings, which is why the authors suspected placental sulphatase deficiency. The placental sulphatase activity was tested by the intravenous application of dehydroepiandrosterone sulphate, and compared with the data obtained from a control patient with normal endocrinological findings. There was a slight increase in DHEA from 7.5 ng/ml to 18.0 ng/ml, whereas the serum values of oestrone and oestradiol did not change. In contrast, the control patient showed an excessive increase of DHEA from 5.5 ng/ml to 56.8 ng/ml. Oestrone and oestradiol also reacted with a strong increase of activity from 12.7 ng/ml to 42.7 ng/ml or 25.2 ng/ml to 61.2 ng/ml, respectively. A placental sulphatase deficiency with absence of hydrolysis of the applied DHEAS must be assumed as the reason for the deficient or absent reaction of DHEA and the oestrogens. The patient gave birth to a healthy boy in the 41st week of pregnancy, delivery being performed by caesarian section. Clinically normal course of pregnancy with lowered oestriol values, delivery by caesarian section in the case of primiparae, as well as male sex of the newborn, are criteria of placental sulphatase deficiency. These criteria correspond to the few observations published so far.
Placental steroid metabolism in a case of placental sulfatase deficiency.
The importance of the placental 3 beta-steroid sulfatase for placental biosynthesis of estrogens is demonstrated by a case report of a placental sulfatase deficiency. The absolute deficiency of this enzyme in our case is demonstrated in vivo by the intravenous dehydroepiandrosterone sulfate loading test and in vitro by placental enzyme tests. Steroid concentrations in serum after injection of dehydroepiandrosterone sulfate (DHEA-S) are compared with those in a group of pregnant women without placental enzyme defects and in a group of nonpregnant women. Placental in vitro tests demonstrate the intact 3 beta-hydroxysteroid dehydrogenase-delta 4,5 isomerase-aromatase-system in the placenta with sulfatase deficiency. The lack of placental hydrolysis results in low concentrations of estrone and estradiol-17 beta in the maternal serum, which are only 5.9% and 12.5%, respectively, of the mean values of the control group. This indicates that more than 90% of estrone and more than 85% of estradiol-17 beta measured in the maternal serum are from DHEA-S as precursor. The remaining concentrations are converted mainly from dehydroepiandrosterone (DHEA), which needs no hydrolysis. Maternal serum concentrations of estriol are under the detection limit of the radioimmunoassay. This is due to the absence of the so called "neutral pathway" and the "phenolic pathway" with 16 alpha-hydroxydehydroepiandrosterone sulfate (16 alpha-OH-DHEA-S) and DHEA-S respectively as precursors. The insignificance of the "placental pathway" for the total biosynthesis of estriol is demonstrated. The placental sulfatase seems to have no great importance for the biosynthesis of the C21-steroids.