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M Levitz

Publications and source records attributed to M Levitz.

At least 55 records · Page 3Linked to original sources
PubMed1984

Hormonally sensitive esterase activity in the mouse uterus results from uptake of plasma esterase.

Mouse uterine homogenates contain an estrogen-sensitive serine esterase (hydrolase II). In immature animals, hydrolase II levels increase rapidly after the administration of estradiol. However, stimulation of de novo synthesis in the uterus has not been demonstrated. In this communication we show that hydrolase II activity in the uterus results from uptake of an esterase from the blood. We describe the purification of this protein from mouse plasma and discuss some of its properties. It appears to be similar if not identical to a sexually dimorphic plasma esterase called albumin esterase or esterase 1 by others. Consistent with this, hydrolysis of estradiol valerate and beta-alanine nitrophenyl ester by either uterine homogenates or purified esterase 1 was blocked by heating or by incubation with diisopropyl flurophosphate or antibody to esterase 1. Levels of the plasma esterase (esterase 1) were 50% higher in adult female mice than in adult males. Levels in juvenile males were in between those in the adult males and females. No significant changes in esterase 1 plasma levels in any group were detected after 4 days of treatment with either testosterone or estradiol. Like the uptake of other plasma proteins, estrogen-stimulated uterine uptake of the plasma esterase was inhibited by prednisolone, but not by puromycin. Using immunoprecipitation of [35S]methionine-labeled esterase 1 prepared in a cell-free translation system, mRNA specific for esterase 1 was found in mouse liver, but not in mouse uterus. Although the natural substrate for esterase 1 (or hydrolase II) is not known, both the purified enzyme and uterine homogenates were able to hydrolyze the valerate ester of estradiol, but not the stearate ester. However, estradiol esters are not necessarily the natural substrates of esterase 1, as only the long chain fatty esters of estradiol are reported to occur in vivo.

Aging↗
PubMed1983

Profile of serum estriol and its conjugates at delivery and in the immediate postpartum period in a patient with severe polycystic kidney disease: a comparison with normal pregnancy.

A patient with group C polycystic kidney disease had abnormally high concentrations of total serum estriol (E3) but low-normal urinary levels of E3 throughout the period of study (20 weeks of gestation until delivery by cesarean section at 33 weeks, 5 days). At delivery and at regular intervals until 6 hours thereafter serum specimens were analyzed for unconjugated E3 and its four major conjugates. Comparisons were made with levels in three normal volunteer subjects studied in the same way. In the 6 hours, total E3 declined 37% in the subject with polycystic kidney disease whereas in normal subjects the decline ranged from 84% to 99%. Unconjugated E3 was depleted from the serum in all subjects in about 2 hours. The major difference between the patient with polycystic kidney disease and the normal subjects was in the profile of E3 conjugates. In polycystic kidney disease, E3-3-glucosiduronate (E3-3G) and E3-3-sulfate-16-glucosiduronate (E3-SG) respectively made up 83% and 1.8% of the total serum estriol, whereas in the normal subjects the average values were 13% for E3-3G and 49% for E3-SG. There were no consistent dramatic changes in the percentage contribution of any conjugate to the total E3 level in either the patient with polycystic kidney disease or the normal subjects in the predelivery or postdelivery periods. The E3 profile in polycystic kidney disease is explainable in terms of impaired renal function coupled with normal enterohepatic metabolism of E3.

Estriol↗
PubMed1983

Properties of an estrogen-induced hydrolytic enzyme from mouse uterus.

The purification and properties of an estradiol-sensitive hydrolytic activity from mouse uterus which fits several criteria for being an induced protein are described. The activity in the uteri of immature animals can be stimulated 2--4-fold by estradiol to that approaching the adult level. Stimulation is blocked by puromycin. The enzyme which we have designated hydrolase II, was purified approx. 400-fold to apparent homogeneity by chromatography on Affigel Blue, DEAE-cellulose and octyl-Sepharose. Hydrolase II is a single chain polypeptide with an estimated mol. wt = 65,000 daltons and has an N-terminal serine residue. A variety of N-blocked L-amino acid nitrophenyl esters are cleaved by the enzyme. Km's at pH 7.2 were all approx. 40 microns. Of substrates tested, phenylalanine nitrophenyl ester had the highest Vmax. Cbz-beta-alanine nitrophenyl ester, which is not a normal protease substrate was cleaved with a Km of 145 microM. The enzyme had no detectable activity against peptide nitroanilide substrates for trypsin-, chymotrypsin- or elastase-like enzymes. It is inhibited by ZPCK and DIFP but not by TLCK and Ala-Ala-Pro-Ala chloromethyl ketone, a potent inhibitor of elastase-like enzymes. Mouse plasma protein protease inhibitors were without effect as was SBTI. Our results rule out hydrolase II being a carnosinase, non-serine esterase, plasminogen activator, collagenase or collagenase activator and suggest that it is a chymotrypsin-like protease.

Animals↗
PubMed1983

On the processing of saliva samples for progesterone assay.

Reports from several laboratories indicate that the concentration of progesterone in the saliva provides a valid indicator of corpus luteum function. However, optimal conditions for the treatment and storage of saliva specimens prior to analysis was not addressed in these papers. We have found that 1) sonication of saliva in brief bursts produces a homogeneous sample from which progesterone is removed quantitatively by a single extraction with hexane in a vortex mixer, and 2) prompt freezing of saliva is important since storage of samples at room temperature for 48 hours results in a significant decrease in radioimmunoassayable progesterone. Four normal women provided daily saliva specimens throughout one menstrual cycle and serum samples every 3 days during the luteal phase. Excellent correlations between the progesterone profiles in the two fluids were obtained.

Adult↗
PubMed1983

Glucosiduronidation of androsterone by human breast tumors in vitro in relation to the progesterone receptor content.

Homogenates of human breast tumors were incubated with 3H-androsterone and the percentage conversions to androsterone glucosiduronate were determined. In addition, separate portions of the tumors were analyzed for estrogen receptor (ER) and progesterone receptor (PR) to see whether conjugation and receptor content could be correlated. Sixteen of thirty-two tumor homogenates formed androsterone glucosiduronate (0.03-5.9%) from androsterone. There was no correlation between ER content and glucuronyltransferase activity. Considering the twenty-six malignant mammary tumors, of the fifteen PR positive types, five (one-third) formed the conjugate. In contrast, almost two-thirds (seven of eleven) of the PR negative tumors formed androsterone glucosiduronate. These correlations indicate a trend, but not of statistical significance.

Androsterone↗
PubMed1983

Estrogen-stimulated uptake of plasminogen by the mouse uterus.

Administration of a single low dose of estradiol to the immature (4- to 5-week-old) female mouse caused a rapid, uterine-specific increase in the uptake of radiolabeled plasminogen from plasma. A significant increase in uptake was detectable within 30 min and reached a maximum 2-4 h after administration of the hormone. After 4 h, a substantial amount (42%) of the newly taken up plasminogen was found in the uterine lumen. Half-maximal stimulation of uptake occurred at a dose of 0.20 microgram estradiol/animal. Estrogen stimulation of uptake was not blocked by puromycin, indicating that new protein synthesis was not required. Similar results were obtained with mouse plasma albumin. Estrogen-stimulated uptake was not blocked by indomethacin (10 micrograms/g BW, iv), but was blocked by prednisolone. Approximately 50% inhibition of the stimulation induced by 0.5 microgram estradiol in these 10-g animals was accomplished with 50 micrograms prednisolone. This study extends our initial findings on the estrogen-stimulated uptake of plasma proteins by the mouse uterus and provides a mechanism by which uterine plasminogen levels can be elevated before implantation.

Adenosine Diphosphate↗
PubMed1982

Uterine hydrogen peroxide concentrations and peroxidase activities in the estrous cycle and perimaturation period of mice.

The concentrations of hydrogen peroxide (H2O2) and peroxidase activity (PA) were measured in mouse uterus during the perimaturation period (4-8 weeks of age) and the estrous cycle. The onset of maturation was accompanied by a spurt in PA but not in H2O2. Neither H2O2 nor PA varied significantly during the estrous cycle. These results differ from those reported in the rat where positive correlations for both with the estrogen state of the uterus were observed.

Aging↗
PubMed1981

Transfer of urea, sodium, and chloride across the perfused human placenta.

Clearance indices (clearance of experimental material: clearance of antipyrine, CI) across the perfused human placenta were determined for urea, sodium, and chloride. The selected materials are of relatively small molecular weight and are water soluble. Clearance of urea was determined under conditions of net transfer and of exchange and no difference was detected. Sodium and chloride clearances were measured as exchange rates. The CI were: urea, 0.32 and 0.38 toward fetus and mother, respectively); sodium, 0.28; and chloride, 0.41 (measured toward the fetus). Recalculation of data as the diffusion limitation (LD) facilitated comparison with data in the literature on the monkey, rabbit, and sheep. LD for urea was comparable among the four species whereas the sheep placenta differed, sharply limiting the diffusion of sodium and chloride. The discrepancy in the sheep between urea and sodium indicates that the low transfer rate of the latter cannot be explained by the "thickness" of the syndesmochorial placenta, as is often stated. Inferences concerning nitrogen metabolism in the fetus have been derived by others from data on transplacental urea gradients and urea clearance. Available data in the human are incomplete but are consistent with amino acids providing approximately 10% of fetal energy needs, with glucose serving as the predominant substrate.

Animals↗
PubMed1981

Glucosiduronidation and esterification of androsterone by human breast tumors in vitro.

The metabolism of 3H-androsterone was studied in homogenates (fortified with uridine 5'-diphosphoglucuronic acid and adenosine 3'-phosphate 5'-phosphosulfate) of eighteen breast tumors, one muscle underlying the primary breast carcinoma and metastatic axillary lymph nodes from a patient with suspected primary breast cancer. The major metabolites identified were less polar than androsterone. On saponification these lipoidal derivatives afforded androsterone as the only product (3 to 48%). Unmetabolized androsterone and lesser quantities of epiandrosterone, 5 alpha-androstane- alpha, 17 beta-diol and 5 alpha-androstane-3,17-dione comprised the free steroid fraction. Androsterone glucosiduronate was isolated (0.17-4.1%) from weight breast tumor homogenates and from the node tissue incubation (17%). There was no apparent correlation between glucuronyltransferase activity and histopathology or estrogen receptor content.

Adenofibroma↗
PubMed1981

Effects of prostaglandin F2 alpha or oxytocin on serum estriol and its conjugates during induced labor.

Twelve patients underwent induction of labor at term, seven by prostaglandin F2 alpha (PGF) and five by oxytocin infusion. Serum samples were drawn before induction and at two hour intervals after infusion was started, throughout labor. The samples were analyzed for estriol (E3) and its principal conjugates, estriol-3-sulfate (E3-3S), estriol-16-glucosiduronate (E3-16G), estriol-3-glucosiduronate (E3-3G), and estriol-3-sulfate-16-glucosiduronate (E3-SG). No significant changes occurred before eight hours of infusion. Two pre-eclamptic patients showed a 100% increase in serum E3 while receiving PGF. The increases correlated best with rising levels of E3-SG. None of the five pre-eclamptic patients given oxytocin showed this striking changes. These observations raise the possibility that PGF may alter the metabolism of estriol in pre-eclamptic patients, during labor.

Estriol↗
PubMed1981

Estrogen-stimulated uptake of alpha 1-protease inhibitor and other plasma proteins by the mouse uterus.

Administration of a single low dose of estradiol to the immature female mouse resulted in a rapid increase in uterine trypsin inhibitory capacity. The increase was apparent within 1 h, reached a maximum in 3--4 h, and returned to base line after 18 h. No corresponding increases were observed in liver or heart. The properties of the uterine inhibitor were found to be essentially the same as those of plasma alpha 1-protease inhibitor (alpha 1-PI). When 125I-labeled mouse plasma alpha 1-PI was given iv to immature mice the administration of estradiol caused a specific stimulation of uterine uptake of the labeled protein that closely matched the estrogen-stimulated increase in uterine trypsin inhibitory capacity. Half-maximal stimulation of uptake occurred at a dose of 0.15 microgram estradiol/animal. After 3 h 97% of the labeled alpha 1-PI taken up by the uterus was in the soluble (105,000 x g) fraction of which 50% was in the lumen. Estradiol also stimulated the uptake of soybean trypsin inhibitor, bovine serum albumin, porcine fibrinogen, and human alpha 2-macroglobulin. Under conditions where puromycin blocked the synthesis of an estrogen-stimulated uterine-specific hydrolase, puromycin had no effect on the estrogen-stimulated uptake of either mouse alpha 1-PI or mouse albumin. These results suggest that the estrogen-stimulated uptake of plasma proteins by the uterus does not require new protein synthesis.

Animals↗
PubMed1981

On the occurrence and transport of estriol-3-sulfate in human breast cyst fluid: the metabolic disposition of blood estriol-3-sulfate in normal women.

The high concentration of estriol-3-sulfate (E3-3S) in human breast cyst fluid has been confirmed in 14 women with multiple cysts. The concentrations of E3-3S found in individual cysts drained within a short time span from the same patient were variable, the ratios ranging from unity to 40. After the iv administration of [14C]estriol or [3H]E3-3S, only minor accumulation of either isotope was detected in the cyst fluids aspirated 6.5-30 h later. Since surprisingly small amounts of isotopes were found in blood, the metabolism of [3H]E3-3S was studied in 2 normal women. The test compound was injected iv, and blood samples were taken at intervals up to 7.5 h. In addition, total urine was collected for 3 days. The blood clearance of [3H]E3-3S was rapid, with the half-life ranging from 15-30 min. However, E3-3S was only a minor component of the urine, indicating rapid tissue extraction and metabolism rather than renal excretion for the compound. The studies indicate that E3-3S of human breast cyst fluid does not equilibrate rapidly with other body pools and that its uptake, if any, from the blood would be against a gradient.

Adult↗
PubMed1980

Plasma estriol and its conjugates following oral and vaginal administration of estriol to postmenopausal women: correlations with gonadotropin levels.

A study was designed to compared the metabolic fate and the biologic effects of 4 mg of estriol (E3) administered either orally or vaginally to six postmenopausal women. Blood samples were collected every hour for 6 hours and five different estriol fractions as well as gonadotropins were measured. Vaginal E3 administration resulted in a decline of 45% in luteinizing hormone (LH) levels and 17% in follicle-stimulating hormone (FSH) levels at 6 hours after treatment (p < 0.05). In contrast, the administration of 4 mg of E3 orally did not produce a decline of LH and FSH, despite the fact that the serum levels of E3-3-sulfate, E3-3-sulfate-16-glucosiduronate, estriol-3-glucosiduronate, and estriol-16-glucosiduronate were all fourfold to 24-fold higher after oral administration than after vaginal estriol administration. However, since the levels of unconjugated E3 were higher after the vaginal than after the oral administration of estriol, we conclude that only unconjugated E3 suppresses gonadotropins.

Administration, Oral↗
PubMed1980

Conjugation of androgens and estrogens by human breast tumors in vitro.

The metabolism of 3H-androstenedione (delta 4-A) and 3H-estriol (E3) was studied in 12 human breast tumors. Part of each tumor was analyzed for estrogen receptor content. Aliquots of tumor homogenates were incubated for 2 hr separately with 3H-delta 4-A and 3H-E3 in the presence of appropriate cofactors. No distinct differences emerged in the profiles of the unconjugated metabolites of 3H-delta 4-A, the major compounds in the approximate order of descendence being androsterone, androstanedione, testosterone, 5 alpha-androstane-3 alpha, 17 beta-diol, epiandrosterone, and dihydrotestosterone. One tumor homogenate from an infiltrating lobular carcinoma converted 3H-delta 4-A to glucosiduronate metabolites (11%), of which androsterone, 6.4%; testosterone, 1.6%; and androstanediol, 0.6% predominated. The homogenate of this tumor and two other tumors converted 3H-E3 to 3H-E3-3S. Conversions of E3 to E3-3S in the other tumor homogenates were less than 0.6%. No correlation between receptor content and the capability of the tumor to conjugate delta 4-A or E3 evolved. However, correlations between steroid hormone metabolism and tumor histopathology may exist.

Adult↗
PubMed1980

Placental transfer of steroids: effect of binding to serum albumin and to placenta.

The transfer rates and placental retention of a series of steroids were measured using an in vitro perfusion system of an isolated cotyledon of human placenta. The steroids were added to the maternal inflow and rates of appearance in maternal and fetal outflows were measured, from which data were calculated the transfer rate and placental retention. With a low concentration of albumin (0.01 g/dl) in the maternal and fetal perfusates, transfer rates of diethylstilbestrol and ethynylestradiol were initially low, with considerable retention of the steroids within the placenta. Transfer rates increased with duration of perfusion. With high concentrations of albumin (1 g/dl), placental retention was greatly reduced and transfer rates very rapidly reached high levels. Albumin in the fetal circulation was the effective factor in increasing transfer rate; maternal albumin reduced it. The results with estrone and progesterone were qualitatively similar but not as striking, posssibly because of the large endogenous concentrations of these two hormones. Placental retention of dexamethasone, a more polar steroid that does not bind to placenta and binds poorly to albumin, was low and there was little difference between transfer from low- and high-protein perfusates.

Biological Transport↗
PubMed1980

A new hormone-response hydrolase activity in the mouse uterus.

A new hydrolase activity has been identified by its capability of cleaving t-boc-Ala-Ala-Pro-Ala-AMC, the released 7-amino-4-methylcoumarin (AMC) being quantified fluorometrically. The activity in the 28,000 X g supernatant fraction of homogenates of weanling mouse uterus was about one fifth that of the adult mouse. The administration of estradiol to the weanling mouse caused a prompt increase in uterine hydrolase, the response being biphasic with peaks at 2 and 6 h. Stimulation was dose responsive and effectively blocked by cycloheximide and puromycin. Estrogen stimulation of hydrolase activity was also observed in the kidney (one fourth that of in the uterus), but not in the heart or liver. Progesterone and testosterone were poor stimulators, but estriol was as effective as estradiol. According to its elution profile in gel filtration, a molecular weight for the hydrolase of about 60,000 is suggested. Inhibition studies in vitro with crude enzyme preparations indicate a serine protease with a SH group essential for maximal activity. The natural substrate for the hydrolase has not been elucidated. It does not solubilize [3H]elastin, and the properties seem to eliminate plasminogen or latent collagenase as possible substrates.

Animals↗