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C A Winkel

Publications and source records attributed to C A Winkel.

49 records · Page 3Linked to original sources
PubMed1981

Deoxycorticosterone biosynthesis from progesterone in kidney tissue of the human fetus.

The levels of deoxycorticosterone (DOC) and DOC sulfate are extraordinarily high in the umbilical cord plasma of human newborns. However, the sources of DOC and DOC sulfate in the human fetus are not defined. Recently, it was shown that plasma progesterone was converted to DOC in extraadrenal tissues in pregnant, nonpregnant, and adrenalectomized women and in men. Thus, DOC formation from plasma progesterone constitutes another example of the formation of a biologically active steroid hormone from a circulating precursor. In addition, the conversion of [3H]progesterone to [3H]DOC in homogenates and microsome-enriched preparations of adult human kidney tissue was demonstrated. To investigate the origin of DOC in the human fetus, we sought 1) to ascertain whether steroid 21-hydroxylase activity was present in human fetal kidney tissue and 2) to establish the kinetics of the reaction catalyzed by this enzyme should it be present in fetal kidney. We employed microsome-enriched preparations of kidney tissue obtained from human abortuses of 9-20 weeks gestation. [3H]DOC formation from [3H]progesterone (1 microM) proceeded in a linear fashion for 3 h. and the rate of formation of [3H]DOC from [3H]progesterone (1 microM) was linear with a microsomal protein concentration between 0.026-0.512 mg X ml-1. The value computed for the apparent Km of steroid 21-hydroxylase in fetal kidney for progesterone was 0.146 microM. We conclude that the human fetal kidney may be an important site of DOC formation as well as a site of DOC action.

Desoxycorticosterone↗
PubMed1981

Deoxycorticosterone sulfate biosynthesis in human fetal kidney.

The levels of deoxycorticosterone (DOC) and DOC-SO4 are extraordinarily high in umbilical cord plasma of human newborns compared to those in plasma of men and nonpregnant women. Progesterone is converted to DOC in minces, homogenates, and microsome-enriched preparations of human fetal kidney tissue. Since DOC, a mineralocorticosteroid, is formed in situ in kidney, its potential site of action, we sought to define whether sulfurylation of DOC also occurred in fetal kidney. We found that radiolabeled DOC-SO4 was formed from [3H]DOC and from [3H]progesterone in minces of human fetal kidneys. C-21 hydroxysteroid sulfotransferase activity was found to be localized principally in the cytosolic fraction of homogenates of human fetal kidney tissue and was present in both the cortical and medullary portions of fetal kidney. In cytosolic fractions prepared from homogenates of human fetal kidneys, we found that the apparent Km of the C-21 hydroxysteroid sulfotransferase for DOC was 4.7 microM; the reaction was linear with time for 60 min and was linear with protein concentration up to 1.2 mg X ml-1 incubation mixture. Thus, DOC-SO4, as well as DOC, is synthesized in the kidney of the human fetus, and kidney may be an important site of formation of these steroids that are found in fetal blood in very high concentrations.

Cytosol↗
PubMed1981

The role of receptor-mediated low-density lipoprotein uptake and degradation in the regulation of progesterone biosynthesis and cholesterol metabolism by human trophoblasts.

Dispersed human placental trophoblastic cells, maintained in primary culture, utilize principally cholesterol derived from low-density lipoprotein (LDL) for progesterone biosynthesis. The rate of secretion of progesterone by these cells increased (100 ng X mg-1 cell protein X 24 h-1 to 390 ng X mg-1 cell protein X 24 h-1) as the LDL concentration in the culture medium was increased (0 to 420 micrograms protein X ml-1). At an HDL-protein concentration of 1000 micrograms protein X ml-1, the rate of progesterone secretion by these cells was one-half that attained by cells maintained in medium containing LDL. The uptake of [125I]iodo-LDL by trophoblastic cells increased at [125I]iodo-LDL concentrations between 0 and 14 micrograms protein X ml-1 in the culture medium, was maximal by 5 to 6 h, and was diminished progressively as the concentration of non-radiolabelled LDL, but not HDL, was increased. Degradation of [125I]iodo-LDL increased as a function of the [125I]iodo-LDL concentration in the culture medium, was linear from 30 min to 32 h, was inhibited by the addition of choloroquine (40 mumol/1) to the culture medium; and was diminished progressively as the concentration of non-radiolabelled LDL, but not HDL, was increased. We observed a reduction in uptake and degradation of [125I]iodo-LDL by these cells as a function of the LDL concentration in the preincubation culture medium. Moreover, when the cells were preincubated with LDL for various times, a 90 per cent reduction in the rate of uptake and degradation of [125I]iodo-LDL was observed after 14 h. These findings are suggestive that trophoblastic cells are capable of down-regulating the number of LDL receptors on the cell surface. The incorporation of radiolabelled oleic acid into cholesteryl esters by these cells was linear for 6 h, increased as a function of the oleic acid concentration in the culture medium, and was stimulated when LDL was present in the culture medium. On the other hand, the synthesis of cholesteryl esters was inhibited half-maximally when the progesterone concentration in the culture medium was 20 mumol/1. Finally, the incorporation of [14C]acetate into cholesterol was inhibited as a function of the LDL concentration in the culture medium. Based on the results of these studies, our belief is that mechanism(s) have been elucidated to define the regulation of (1) progesterone biosynthesis; (2) de novo cholesterol synthesis; (3) intracellular cholesteryl ester storage; and (4) LDL uptake by normal human trophoblastic cells.

Cholesterol↗
PubMed1981

Plasma concentrations of 11-deoxycorticosterone in women during the menstrual cycle.

As plasma 11-deoxycorticosterone (DOC) can arise from adrenal secretion and from 21-hydroxylation of plasma progesterone in extraadrenal tissues, alterations in plasma progesterone concentrations might alter significantly the plasma DOC levels in humans. Therefore, the authors measured DOC in plasma of 6 normal, ovulatory women daily throughout their menstrual cycles and in plasma of normal men. The plasma DOC concentrations in women during the follicular phase, when plasma progesterone levels are low, were also low (42 +/- 1.7 pg/ml, mean +/- SE). An increase in the plasma levels of DOC and progesterone occurred at midcycle. The plasma DOC levels remained elevated (P less than .001, as compared with levels during the follicular phase) throughout most of the luteal phase (119 +/- 7.9 pg/ml), declining prior to the onset of menses. However, the plasma levels of cortisol and dehydroepiandrosterone sulfate did not fluctuate during the cycle. The plasma DOC levels in men were 57 +/- 4.3 pg/ml (N = 10). The authors conclude that, during the ovarian cycle of women, significant changes in the plasma levels of DOC occur that are coupled to fluctuations in plasma progesterone concentrations.

Dehydroepiandrosterone↗
PubMed1980

Deoxycorticosterone biosynthesis in human kidney: potential for formation of a potent mineralocorticosteroid in its site of action.

The extra-adrenal formation of deoxycorticosterone (DOC) from plasma progesterone has been demonstrated in humans. In those studies it was shown that in some persons the volume of plasma cleared of progesterone by DOC formation was great, namely, 75 liter/24 hr. Because steroid 231-hydroxylase activity [steroid 21-monooxygenase; steroid, hydrogen-donor:oxygen oxidoreductase (21-hydroxylating), EC 1.14.99.10] could not be demonstrated in homogenates or microsome-enriched preparations of human lung or liver tissue, we speculated that the 21-hydroxylation of plasma progesterone might take place in the kidney. Employing whole tissue homogenates and microsome-enriched preparations of human kidney tissue, we demonstrated the formation of [3H]DOC from kidney tissue, we demonstrated the formation of [3H]DOC from [3H]progesterone. The rate of formation of DOC from progesterone in microsomal preparations from kidney tissues of adult humans varied from 0 to 803 pmol per mg of microsomal protein per hr. The value computed for the apparent Km of the enzyme for progesterone was 0.140 microM. On the basis of these findings, we conclude that steroid 21-hydroxylase activity is present in human kidney tissue and that the kidney may be an important site of DOC formation as well as a site of DOC action.

Cell-Free System↗
PubMed1980

Conversion of plasma progesterone to deoxycorticosterone in men, nonpregnant and pregnant women, and adrenalectomized subjects.

During the third trimester of human pregnancy the concentrations of deoxycorticosterone (DOC) in maternal plasma are 4-50 times those in nonpregnant women and men. It has been suggested that the increased amount of DOC in maternal plasma originates in the fetal compartment. We considered an alternate explanation for the high levels of DOC in plasma or near-term pregnant women, viz., that DOC may be derived in part from 21-hydroxylation of maternal plama progesterone. To test this hyposthesis we measured the fractional conversion of plasma progesterone to DOC from the relationship between the 3H:14C ratio of the infused tracers, [3H]progesterone and [14C]-DOC, and the 3H:14C ratio or urinary 3 alpha,21-dihydroxy-5 beta-pregnan-20-one (tetrahydro-DOC). The fractional conversion of plasma progesterone to DOC ([rho](BU)P-DOC), measured in this manner, was 0.007 +/- 0.001 (mean +/- SEM, n = 26) in the subjects of this study. The values for [rho](BU)P-DOC varied widely among subjects (0.002-0.022) but the range of values for [rho](BU)P-DOC was similar among women pregnant with an anencephalic or dead fetus, nonpregnant and adrenalectomized women, and men. The transfer constant of conversion of progesterone to DOC in plasma, [rho](BB)P-DOC, remained constant in a nonpregnant woman during the infusion of nonradiolabeled progesterone at rates of 0-14 mg/h. Based on the results of these studied, we conclude that DOC is formed by extra-adrenal 21-hydroxylation of plasma progesterone and that the rate of formation of DOC by this pathway is proportional to the concentration of progesterone in plasma.

Adrenalectomy↗
PubMed1980

Uptake and degradation of lipoproteins by human trophoblastic cells in primary culture.

It has been shown previously that human placental trophoblastic cells use principally lipoprotein-cholesterol for progesterone synthesis. In the present investigation, human placental trophoblastic cells in primary culture were employed to study the kinetics of uptake and degradation of lipoproteins by trophoblastic tissue. Maximal uptake of [125I]iodo-low density lipoprotein ([125I]LDL) by these cells was achieved by 5-6 h, while degradation of [125I]iodo-LDL was linear from 30 min to 32 h. Uptake and degradation of [125I]iodo-LDL as a function of substrate concentration was studied. The apparent dissociation constants (KD) for both uptake and degradation processes were calculated from these data and were found to be similar (1.03 X 10(-8) and 6.8 X 10(-9) M, respectively), a finding which is suggestive that these processes are causally related. Chloroquine inhibited [125I]iodo-LDL degradation by these cells, a finding that is indicative that LDL degradation is dependent on lysosomal proteolytic activity. When nonradiolabeled high density lipoprotein (HDL) was added to the culture medium, there was little effect on either uptake or degradation of [125I]iodo-LDL; however, when nonradiolabeled LDL was added to the culture medium the net uptake and degradation of [125I]iodo-LDL were diminished progressively as the concentration of nonradiolabeled LDL was increased, findings which are indicative of specificity of the LDL receptor. Uptake and degradation of [125I]iodo-HDL by these cells as a function of substrate concentration were examined. Uptake of [125I]iodo-HDL increased in a linear fashion as the concentration of [125I]iodo-HDL was increased up to 1000 microgram protein/ml; however, degradation of [125I]iodo-HDL was negligible. It is concluded that utilization of lipoproteins by human placental trophoblastic cells is mediated by high affinity, low capacity receptors specific for LDL. These cells do not degrade the protein component of HDL.

Biological Transport↗
PubMed1980

Production rate of deoxycorticosterone in women during the follicular and luteal phases of the ovarian cycle: the role of extraadrenal 21-hydroxylation of circulating progesterone in deoxycorticosterone production.

The fractional conversion of plasma progesterone to deoxycorticosterone (DOC) ([rho]BU P-DOC) has been determined in pregnant, nonpregnant, and adrenalectomized women and men. The [rho]BU P-DOC varies widely among persons, but the [rho]BU P-DOC in a given subject is invariant regardless of plasma progesterone concentrations. In the present investigation we sought to ascertain 1) the production rate of DOC (PR-DOC) during the follicular and luteal phases of the ovarian cycle of women and 2) the role of extraadrenal 21-hydroxylation of progesterone as a source of DOC during the luteal phase of the ovarian cycle. Four subjects were given iv infusions of [3H]progesterone and [14C]DOC in order to determine [rho]BU P-DOC and the PR-DOC during both phases of the ovarian cycle. The [rho]BU P-DOC found in these subjects were within the range of values previously reported, viz. 0.007 +/- 0.001 (mean +/- SEM), and did not change during the cycle. The mean daily PR-DOC in these subjects during the follicular phase of the menstrual cycle was 58 microgram/24 h, whereas the mean daily PR-DOC during the luteal phase was 318 microgram/24 h. In each subject the PR-DOC during the luteal phase was 4--7 times greater than the PR-DOC during the follicular phase of the cycle. The increase in plasma concentrations of DOC during the luteal phase of the ovarian cycle apparently results from extraadrenal formation of DOC from circulating progesterone.

Adult↗
PubMed1976

Scalp abscess: a complication of the spiral fetal electrode.

During the period from September, 1974, to January, 1975, we performed 276 deliveries, of which 54% were internally monitored with a spiral type of fetal electrode. Eight of the infants monitored (incidence, 5.4%) developed scalp abscesses. We had had no previous complications associated with the electrodes. An intensive investigation was conducted to detect the causative factor(s) of the fetal scalp infections. Case histories of the mothers and infants were scrutinized, instruments were examined, the environment and techniques were analyzed. A survey of maternal and infant complications during the period from September, 1973, to August, 1974, served as control. The findings indicated that a different type of coil electrode had been substituted for the brand we had used previously. The new coil electrode had a barb at the tip, presumably to prevent its falling out of the scalp. We discontinued the use of the coil which had become suspect and returned to the type we had used previously. We have not had another incidence of fetal scalp infection associated with intrapartum monitoring.

Abscess↗
PubMedDate not supplied

Androgen metabolism by human peritoneal macrophages.

Peritoneal macrophages (PM) were obtained by peritoneal dialysis from a regularly menstruating woman with renal failure. Macrophages (10(6) cells) were incubated at 37 degrees C for various periods of time (0-4 hr) in the presence of 14C-androstenedione or 3H-androstenedione and various concentrations (0.06-5.06 microM) of nonradiolabeled androstenedione (A). Testosterone (T) formed was purified by column chromatography, thin layer chromatography, acetylation, and recrystalization to constant 3H:14C ratios. The rate of formation of T from A was linear for nearly 2 hr. Conversion of A to T was linear at cell numbers in the incubation up to 1 x 10(6). The formation of T from A followed Michaelis-Menten kinetics at concentrations of A between 0.06 and 5.06 microM. The apparent Km of the enzyme for A was 0.75 microM and the Vmax for T formation from A in these cells was 33.9 pmol x hr-1 x 10(6) cells-1. PM were obtained also from normal patients (n = 6) and patients with endometriosis (n = 5). The rate of T synthesis from A in PM obtained from patients with endometriosis [527 +/- 263 pmol x hr-1 x 10(6) cells-1 (mean +/- SEM, n = 5)] was similar to that observed in PM obtained from normal patients [518 +/- 226 pmol x hr-1 x 10(6) cells-1 (mean +/- SEM, n = 6)]. We observed a near 30-fold variation in the rate of formation of T from A by PM obtained from different individuals (range 54 to 1580 pmol x hr-1 x 10(6) cells-1). Further study is needed to elucidate the physiologic significance of PM androgen metabolism and its relationship to reproductive function.

Adult↗
PubMedDate not supplied

Is the standard of care what we think it is?

For the most part, gynecologists are actually unaware of the issues involving surrogate versus quality of life outcomes, the "deceptive practice of medicine" and the true incidence of complications as they relate to the standard of care. An anonymous survey of 1958 practicing gynecologists attending seven national symposia revealed a significant number of unreported complications. Clearly, the standard of care (at least with regard to complication risk) is markedly different than has been suggested by the medical literature. Concomitantly, we suggest that physicians need to take a more active role in the policing of our own specialties.

Female↗