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Biomedical subjects

L Cedard

Publications and source records attributed to L Cedard.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1976

[Glycogen phosphorylase activity of full term immature human placentas].

Human placenta contains glycogen phosphorylase activity (E.C. 2.4.1.1) in two interconvertible forms, one is already active and the other is actibatable by 5' AMP. The human placenta contains also a sufficient amount of endogenous phosphorylase b kinase and phosphorylase a phosphatase, to allow this interconversion. The phosphorylase activity is higher in immature placentas than in full-term organs, as in the latter the inactive phosphorylase is only partially revealed by 5' AMP as in other steroidogenic organs. By contrast, in immature placentas the inactive glycogen phosphorylase is completely revealed by this nucleotide.

Cyclic AMP↗
PubMed1976

[Deficiency in placental sulfatase. Clinical and biochemical study of 3 cases].

Placental sulfatase deficiency is currently undetected because of the lack of clinical manifestation. However, such a diagnosis should be borne in mind as it would be unadequate to undertake drastic therapy thinking of acute foetal disease or anencephaly. In the case of a clear answer, the dynamic tests allow to diagnose prenatally the defect causing paradoxical low excretion of maternal urinary estrogens and so, to await in perfect safety for the birth of an healthy baby. The enzymatic defect can be confirmed by the biochemical study of placenta tissue in vitro. In the case of an unclear answer to the DHA-S and free DHA tests, we recommend to determine the foetal chromosomal sex before ascertaining the diagnosis.

Adult↗
PubMed1975

[Metabolism of pregnenolone 16-3H and progesterone 4-14C by 18 day fetal mouse gonads in organotypic culture. Effect of the gonadotropic hormone LH].

Fetal mice testes convert pregnenolone-16-3H and progesterone-4-14C to testosterone in organ culture. The 3H/14C ratio in progesterone and testosterone fractions isolated from culture media suggests the importance of the delta5-3 beta hydroxysteroid pathway in our experimental conditions. LH decreases radioactive testosterone production and increases the activity of the kelta4-3-ketosteroid pathway.

Animals↗
PubMed1975

[Delta 5-3 beta hydroxysteroid dehydrogenase activity in the human full term placenta after culture: the effect of chorionic gonatropin].

The study made by histochemistry shows that the delta5-3 beta-hydroxysteroid-dehydrogenase (delta5-3 beta-HSDH) activity which is positive in the fresh placental tissue disappears after 24 h of culture but is maintained much longer if culture medium is supplemented with human chorionic gonadotropin (15 UI of HCG). The biochemical study confirms the delta5-3 beta-HSDH activity decrease during the first 24 h of culture. The enzymatic activity is restored during the following six days and this phenomenon is stimulated by the addition of HCG in the culture medium.

Chorionic Gonadotropin↗
PubMed1975

[Kinetic study of the in vitro penetration and metabolism of cholesterol sulfate in the human placenta : demonstration of a direct formation of pregnenolone sulfate].

The direct metabolism of cholesteryl-sulfate into pregnenolone sulfate is pointed out during in vitro perfusion of the whole organ and incubation of slices. The metabolite so formed represents a significant fraction of the recovered radioactivity. Cholesteryl-sulfate, which may be hydrolyzed into cholesterol, as well, is considered as a possible precursor of placental steroidogenesis and particularly of progesterone. Differences in the cellular permeability depending on the experimental model considered appear again during these experiments.

Cell Membrane Permeability↗
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↗
PubMed1975

Isolation and in vitro translation of human placental lactogen messenger RNA from human term placenta.

A messenger activity for HPL was identified in normal human term placentas. The mRNA was translated in rabbit reticulocyte cell-free system. The HPL synthesized was quantified by a specific immunoprecipitation and further identified by electrophoresis on sodium dodecyl sulfate polyacrylamide gel. The HPL synthesized in the reticulocyte lysate exhibited a molecular weight between 20,000 and 22,000 daltons similar to the active hormone. The messenger RNA activity for HPL corresponded to a sedimentation coefficient of 11-12 S. Furthermore the messenger activity for HPL was preferentially associated with membrane bound polyribosomes than with free polyribosomes.

Cell Membrane↗
PubMed1975

Smoking, human placental lactogen and birth weight.

Human placental lactogen (HPL) was measured in 525 serum samples from 144 pregnant women and related to smoking habits and the birth weight of their infants. Women smoking during pregnancy were found to have a level of HPL significantly lower than the non-smokers (p less than 0.05). A significant correlation between HPL and birth weight was found (r=0.38); p less than 0.001) which remained significant when smoking was held constant (r=0.35; p less than 0.001). There was no relationship between birth weight and smoking when HPL was held constant.

Birth Weight↗