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L Savu

Publications and source records attributed to L Savu.

At least 55 records · Page 3Linked to original sources
PubMed1980

[Free polyunsaturated fatty acids, estrogens and fetoproteins].

In the course of the foetal development of numerous animal species elevated serum concentrations of alpha-1-foetoprotein (AFP) are observed. The level of this foetal protein decreases after birth, but reappears in several pathological cases characterized by a cellular proliferation, in particular in neoplasia such as hepatoma and teratoblastoma. Little was known until 1971 on the biological role of this carcino-embryonic antigen. It has been since evidenced [Nunez and al., 1971, C.R. Acad. Sci., Paris, 273, 834-841]. That rat and mouse AFPs bind oestrogens with high affinity (Ka = 10(8) M-1) [Savu and al., 1972, F.E.B.S. Let., 22, 113-116]. Human AFP does not possess this property. We have recently shown [Benassayag and al., 1977, Steroids, 30, 771-785] that the sera from pregnant rats, rat and human foetuses contain compounds which behave as competitive inhibitors of the estrogen binding on rat or mouse AFP. We have subsequently identified this substances as a mixture of non-esterified fatty acids (NEFA) [Vallette and al., XXVII Colloquium "Protides of the biological fluids", Bruxelles, H. Peeters Ed., Pergamon Presse, 1979]. We have measured [BENASSAYAG and al., Oncodevelopmental biology and medicine, in press] the association constants of each NEFA of the serum mixture with rat AFP, the polyunsaturated fatty acids (PUFA) (C 20:4, C 22:4, C 22:6) show the highest association constants (Ka = 10(5)-10(6) M-1). We have also confirmed that human AFP binds the PUFA with high affinity. The biological perspectives opened up by these novel data will be discussed.

Animals↗
PubMed1980

High affinity of nonesterified polyunsaturated fatty acids for rat alpha-fetoprotein (AFP).

We have recently demonstrated that a mixture of nonesterified long chain fatty acids, mainly polyunsaturated, which are extracted under certain conditions from either whole mammalian sera or from pure rat alpha 1-fetoprotein (AFP), interfere with rat AFP-estrogen interaction. We present here a quantitative study of the association constants for the binding to AFP of these different fatty acids. We show important differences among them, the polyunsaturated ones displaying higher association constants (Ka approximately 10(7) -- 10(8) M-1) than the monounsaturated (Ka approximately 10(6) M-1) or the saturated (Ka approximately 10(4) -- 10(5) M-1) compounds. Moreover, though all the fatty acids identified in rat serum or rat AFP extract are more or less tightly bound by rodent AFP, only some of them can compete for exogeneous estrogens complexed to this highly estrophilic macromolecule.

Animals↗
PubMed1979

Relations between fatty acids and oestrogen binding properties of pure rat alpha 1-foetoprotein.

A delipidation procedure based on treatment with charcoal at pH 3 has been applied to highly purified rat alpha 1-foetoprotein preparations. The oestrogen binding properties of the delipidated proteins have been studied with an equilibrium dialysis technique, and compared with the properties of the untreated foetal protein, as well as those of preparations reconstituted from the defatted alpha 1-foetoprotein and the removed lipids. An important increase has been evidenced for the binding levels of oestrone, oestradiol-17 beta and diethylstilboestrol by the delipidated alpha 1-foetoprotein. A reversal of this effect has been obtained by incubating the delipidated protein either with the lipids extracted from the purified alpha 1-foetoprotein or with a potent competitor of the rat alpha 1-foetoprotein-oestrogen interaction, designated as 'L', previously demonstrated and isolated from whole rat sera, and tentatively characterized as a mixture of fatty acids. Scatchard analysis of the oestrone and oestradiol-17 beta binding parameters show that the enhanced fixation of the hormones after defatting is primarily due to a two-fold increase of the apparent number of binding sites/mol alpha 1-foetoprotein. The results are interpreted in terms of the probable, at least partial, identity between the lipids closely associated with the pure alpha 1-foetoprotein and the fatty acid mixture 'L' isolated from whole sera. The possible biological role of complex interplay between oestrophilic alpha 1-foetoproteins, phenolsteroids and fatty acids in the control of oestrogen levels during development is discussed briefly.

Animals↗
PubMed1979

Ligand properties of diethylstilbestrol: studies with purified native and fatty acid-free rat alpha 1-fetoprotein and albumin.

We report the equilibrium binding parameters for the interactions of the estrogen analogue diethylstilbestrol (DES) with highly purified rat alpha 1-fetoprotein (AFP) and serum albumin preparations. At 25 degrees C and pH 7.4, an association constant (Ka) of about 1.5 X 10(6)M-1 and 2 sites/mole are measured with the DES-AFP system, whereas for the DES-albumin interaction, we find a Ka of approximately 2 X 10(5)M-1 and about 11 sites/mole of protein. The removal of fatty acids from pure AFP causes a reversible 3 fold increase of the number of DES binding sites; the same delipidation procedure applied to albumin slightly diminishes its DES binding parameters. We also demonstrate the capability of DES to displace competitively estradiol-17 beta (E2) from its high affinity sites on the estrophilic rat AFP. Finally, the binding behaviour of the two serum proteins towards the synthetic estrogen is compared to their interaction with the natural hormones. The physiological and pharmacological relevance of these data is discussed.

Animals↗
PubMed1977

Rat and human embryo and post-natal sera contain a potent endogenous competitor of estrogen-rat alpha-fetoprotein interactions.

A highly active inhibitor of the binding of estrone and estradiol-17beta to rat alpha-fetoprotein is demonstrated for the first time in embryo, immature and adult rat sera as well as in fetal and adult human sera. The competitive character and the narrow specificity of this inhibition effect is shown. The major compound responsible for this activity is isolated by successive column Sephadex LH20 and thin layer chromatography: it is characterized as a nonpolar, nonphenolic, dialysable and thermostable substance, unreactive towards anti-estrone and anti-estradiol-17beta antibodies. The possible biological role of an endogenous non-estrogen ligand of rodent fetoproteins is discussed.

Adrenalectomy↗
PubMed1975

Plasma diethylstilboestrol binding proteins of rat, mouse and man in the course of development: relations with the binding of estradiol.

High diethylstilboestrol (DES) binding has been demonstrated in fetal and adult sera from man, rat and mouse by equilibrium dialysis and electrophoretic techniques. In the adults of the three species and in the human fetus only albumin shows an elevated binding capacity for DES. By contrast, in the case of rat and mouse embryos there are two proteins, namely albumin and alpha-fetoprotein, which afford major and quantatively similar contributions to the binding. Human alpha-fetoprotein does not bind DES. These phenomena are analysed in relation to the estrogen binding characteristics of the alpha-fetoproteins of the three species.

Aging↗
PubMed1972

Etude des constantes de liaison entre les oestrogenes et 1'alpha(1)-foetoproteine de rat.

The binding constants of the alpha(1)-foetoprotein of the rat embryo serum for oestrone and oestradiol-17beta have similar values, i.e. 1 x 10(8) M(-1) in average at 25 degrees. There is probably one binding site per mole of binding protein. The high alpha(1)-foetoprotein concentration in the rat embryo serum at 17-19 days of pregnancy explains the exceptionally high levels of fixation of the phenolsteroids by this serum.

Journal Article↗