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F Ferre

Publications and source records attributed to F Ferre.

At least 55 records · Page 3Linked to original sources
PubMed1986

Characterization of a myc-containing retrovirus generated by propagation of an MH2 viral subgenomic RNA.

We have previously isolated, from wild-type MH2 virus that contains the two oncogenes mil and myc, mutants defective in one or the other oncogene product. We report here the molecular cloning and extensive characterization of MH2 CL25 provirus lacking the v-mil oncogene. Our results indicate that this virus corresponds to the propagation of the 2.8-kilobase subgenomic RNA of MH21.

Base Sequence↗
PubMed1986

Cyclic AMP metabolism in the inner and outer layers of human myometrium near term.

The metabolism of cAMP which appears to be the intracellular mediator of various relaxing agents was studied in biopsies obtained during elective caesarean section from inner and outer myometrial layers outside the placental insertion. In the inner layer, L-epinephrine, PGE1, PGE2, PGF2 alpha and PGI2 stimulated the cAMP formation process while 6-keto PGF1 alpha was ineffective. The fact that some of these prostaglandins are well-known to promote contraction, confirms that the effects of drugs on uterine motility are not necessarily related to changes in the cAMP level. On the other hand, L-epinephrine and prostaglandins did not strongly influence the cAMP formation process in the outer layer. Kinetic analysis and purification assays of phosphodiesterase (PDE) which catalyzes the degradation of cAMP revealed the presence of multiple molecular forms of the enzyme in human pregnant myometrium. Qualitative and quantitative differences between the two layers appeared in the two forms separated from the soluble fraction by DEAE-cellulose chromatography. An unequal distribution of calmodulin was also observed in the inner and outer layers. Our results support the concept of the regulatory heterogeneity of the pregnant human uterus and suggest that the myometrial inner layer plays an important role in the regulation of uterine motility at the end of pregnancy.

Calmodulin↗
PubMed1985

Cyclic 3':5'-nucleotide phosphodiesterase in human myometrium at the end of pregnancy: partial purification and characterization of the different soluble isoenzymes.

Most of the cyclic nucleotide phosphodiesterase (PDE) activity of pregnant human myometrium was found in the soluble fraction. Chromatography of this fraction on DEAE-cellulose resolved two peaks of PDE activities. Peak I hydrolyzed both cAMP and cGMP and was activated by the Ca2+-calmodulin complex. Peak II, insensitive to this complex, hydrolyzed specifically cAMP. Sucrose gradient centrifugation of the soluble fraction resolved three peaks (A, B, C) of cAMP PDE activities, and only the first two peaks (A, B) were active towards cGMP. A subsequent sucrose gradient centrifugation of peak I, previously determined by DEAE-cellulose, allowed us to restore two peaks A and B identical to those directly obtained from the soluble fraction: peak A hydrolyzes both substrates, while peak B is specific to cGMP hydrolysis. For peak II, a single large cAMP PDE activity peak is generated. Considering Ca2+ and cAMP as intracellular messengers in the control of uterine motility, the characterization of the different forms of PDE in pregnant human myometrium will be of importance in developing improved tocolytic therapy.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1985

A longitudinal study of cyclic nucleotide phosphodiesterase activity and its relationship with nucleic acid content in the myometrium of cynomolgus monkeys (Macaca fascicularis) between days 39 and 162 of gestation.

Cyclic AMP and cGMP phosphodiesterase (PDE) activities and nucleic acid contents were assayed in crude homogenates prepared from biopsies excised between days 39 and 162 of gestation (normal full length of gestation: 165 days) in outer and inner layers of the macaque myometrium. In both layers, kinetic analysis of PDE indicated high (apparent Km 2 X 10(-6) M) and low (apparent Km 2 X 10(-5) M) affinity component for each substrate. When measured in high-affinity conditions, specific activities were elevated around day 40 and beyond day 130 of gestation. By contrast, low values were observed between days 50 and 100. They were related to the decrease of the Vmax values (expressed either per milligram protein or per microgram DNA). No significant differences were observed between outer and inner layers. Variations of tissue DNA and RNA were demonstrated throughout gestation indicating that both hyperplasia and hypertrophy were involved in uterine growth. Unlike DNA, RNA content (and consequently the RNA:DNA ratio) in the inner layer always remained above the values of the outer layer. In both layers, the RNA:DNA ratio, which presumably reflects the rate of protein synthesis and the PDE activity, reached maximum values at the same time.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1985

Relationship between myometrial cyclic nucleotide phosphodiesterase (PDE) activity and the RNA/DNA ratio at various stages of gestation in primates.

Cyclic AMP and cGMP PDE activities were assayed in crude homogenates prepared from biopsies excised between day 39-162 of gestation (normal length of gestation, 165 days) in outer and inner layers of the macaque myometrium. In both layers, kinetic analysis of PDE indicated high (app Km approximately equal to 2 X 10(-6)M) and low (app Km approximately equal to 2 X 10(-5)M) affinity component for each substrate. Measured in high affinity conditions, specific activities were increased around day 40 and beyond day 130 of gestation. By contrast, low values were observed between days 50 and 100. No significant differences were observed between outer and inner layers. In both layers, the RNA/DNA ratio, which presumably reflects the rate of protein synthesis, culminated at the same time as the PDE activity. These variations were observed in the myometrium at specific stages of gestation. In late pregnancy, the human myometrium also displayed biphasic kinetics for cAMP and cGMP PDE activities. Non-human primates may be a partially representative model of what happens in the human myometrium.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1985

Influence of the oral administration of micronized progesterone on plasma and tissue levels of steroids in human pregnancy.

A single dose of micronized progesterone, orally administered to women at different stages of pregnancy, induced an immediate increase in the plasma levels of progesterone. Progesterone was administered to another group of women just before elective cesarean section. Levels of progesterone, oestradiol-17 beta and oestrone were determined in plasma, placenta and at different sites of the myometrium obtained during the surgical procedure. Results were compared to those observed in a control group of women who did not receive progesterone. Progesterone levels demonstrated a marked increase in plasma and in the whole myometrium 150 min after administration; the levels then decreased rapidly to control values within one hour. The concentrations of progesterone in the placenta did not show any change. Evident modifications of the oestrogen levels appeared in the myometrium and in the placenta after the administration of progesterone whereas no change occurred in the plasma. No difference was observed in estradiol-17 beta in the myometrium whereas an increase was seen in the placenta. Estrone levels decreased in the myometrium and in the placenta. This study demonstrates a prompt delivery of an orally administered natural progesterone to the myometrial target tissue and subsequent modifications in the estrogen pattern. This provides a theoretical mechanism for the clinical use of progesterone in the prevention of premature labor.

Administration, Oral↗
PubMed1984

Oral administration of micronized natural progesterone in late human pregnancy. Effects on progesterone and estrogen concentrations in the plasma, placenta, and myometrium.

A single dose of micronized oral progesterone was administered to 15 pregnant women immediately prior to elective cesarean section. Levels of progesterone, 17 beta-estradiol, and estrone were measured in the plasma, in the placenta, and at different sites in myometrium obtained during the surgical procedure. Results were compared to those observed in a control group of women who did not receive progesterone. Progesterone levels demonstrated a marked increase in plasma and in the whole myometrium 150 minutes after administration. The levels then decreased rapidly to control values in 1 hour. The concentrations of progesterone in the placenta did not show any changes. No difference appeared in 17 beta-estradiol levels in the plasma or the myometrium, whereas an increase was observed in the placenta. Estrone levels did not change in the plasma, but they decreased in the myometrium and in the placenta.

Administration, Oral↗
PubMed1984

Evolution of cAMP phosphodiesterase activity in cultured myometrial cells: effects of steroids and of successive subcultures.

Cyclic AMP phosphodiesterase (PDE) activity was characterized in culture of ewe myometrial cells and its sensitivity to steroid hormones was tested. Cultured myometrial cells were maintained from the first to the 20th subculture in the presence of 2% of serum in a medium supplemented with 1 microM of insulin. It was found that myometrial cells possess a PDE activity with atypical kinetics. The nonlinear responses in Lineweaver-Burke plots suggest the presence of high- and low-affinity PDE activities. In cell culture, apparent Km values were similar to those obtained from the original myometrium. Vmax values increased with successive subcultures, revealing an increase in the capacity of the cells to degrade cAMP; in parallel, the growth rate decreased. The PDE specific activity in cultured myometrial cells was inhibited by estradiol or progesterone. When added together, no synergistic effect was obtained. The rate of inhibition for both steroids was constant during successive passages for both low- and high-affinity conditions. Results obtained in myometrial cell long-term culture were compatible with reports in other species in vivo. Considering the role of cAMP in the regulation of uterine functions, subcultured myometrial cells provided us a useful experimental system with which to study the cAMP metabolism process.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1982

Effects of prostaglandins on cyclic nucleotide phosphodiesterase activity in the human term placenta.

Slices of human full-term placentas, obtained by elective cesarean section, were incubated in the absence or presence of prostaglandins (PGs) and the cyclic AMP phosphodiesterase (cAMP PDE) activity was measured. PGE1 and PGI2 were shown to stimulate cAMP PDE activity. The effect of PGE1 is related to an increase in the Vmax of the low Km activity without alteration of this apparent Km. Several findings suggest that the cAMP PDE is activated by its own substrate; PGE1 and PGI2, promote an increase of cAMP formation which is observed before the cAMP PDE activation. Dibutyryl cAMP or theophylline also activate cAMP PDE. In contrast, PGF2 alpha does not influence either adenylate cyclase or AMP PDE. In addition, we found that the ability of the placenta to degrade cAMP, increases after parturition. PG levels are higher in the foeto-placental unit during labor, and a causal relationship between these two phenomena is possible. Our data supporting the concept of hormonal control of cAMP PDE is consistent with the hypothesis that an accelerated cAMP metabolism in placenta contributes to the maintenance of a constant equilibrium of the cyclic nucleotide levels in the foeto-placental unit.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1980

Steroid concentrations and delta 5, 3 beta-hydroxysteroid dehydrogenase activity in human placenta. Comparison between elective cesarean section and spontaneous vaginal delivery.

The level of delta 5, 3 beta-hydroxysteroid dehydrogenase (delta 5, 3 beta-HSDH) was measured in the mitochondrial and microsomal fractions of the human term placenta. The capability of the placenta to transform pregnenolone to progesterone was found to be significantly higher after spontaneous vaginal delivery than after elective cesarean section (p < 0.001). There was a significant rise in the placental concentration of estrone occurring at the time of parturition (p < 0.01). The placental concentration of estradiol-17 beta was also greater after than before parturition but the diffference was not statistically significant. Conversely to the estrogen concentration, no difference existed in the progesterone concentration between the two groups of placentas. The significance of these findings is discussed in relation to the parturition process.

3-Hydroxysteroid Dehydrogenases↗
PubMed1977

[3'5'-Cyclic AMP phosphodiesterase activity in the internal and external layers of human myometrium at the end of pregnancy].

The hydrolysis of cAMP by phosphodiesterase was studied in whole homogenate from human myometrium at the end of the pregnancy before onset of labour. Tissue samples were taken from outer and inner layers of placental and anti-placental sites. Kinetic analysis shows in every case two apparent Km values for low and high cAMP concentrations in the order of 1 x 10(-5) M and 1 x 10(-4) M. On the other hand Vmax values are lower for the enzyme isolated from the placental site than for the one isolated from the anti-placental area. In the 4 zones studied, an appreciable proportion of the low Km enzyme is present.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1975

Human placental delta5-3beta hydroxysteroid dehydrogenase activity (delta5-3beta HSDH): intracellular distribution, kinetic properties, retroinhibition and influence of membrane delipidation.

Delta5-3beta HSDH activity has been assayed either by spectrophotometric method or by use of radioactive substrates. The enzymatic activity is equally distributed between mitochondrial and microsomal fractions verified by electronic microscopy. The specific activity is comparable in both fractions, as well as the optimal pH and the Km for NAD and for the substrates. The delta5-3beta Hut optimal pH, specific activity and sensitivity to the inhibitory action of various steroids are different when C19 and C21 steroids are used as substrates. Estrogens and cyclic AMP have also an inhibitory action on the oxidation of C21 steroids. Treatment of microsomal or mitochondrial membranes with phospholipase A releases fatty acids (mainly arachidonic) and decreases the enzymatic activity. "Adsorbtion" of the fatty acids on bovine serum albumin partially reactivates the delta5-3beta HSDH.

Adenosine↗